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+The Project Gutenberg eBook, Aviation Engines, by Victor Wilfred Pagé
+
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+
+
+
+Title: Aviation Engines
+       Design--Construction--Operation and Repair
+
+
+Author: Victor Wilfred Pagé
+
+
+
+Release Date: December 2, 2011  [eBook #38187]
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+
+***START OF THE PROJECT GUTENBERG EBOOK AVIATION ENGINES***
+
+
+E-text prepared by Juliet Sutherland, Harry Lamé, and the Online
+Distributed Proofreading Team (http://www.pgdp.net)
+
+
+
+Note: Project Gutenberg also has an HTML version of this
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+
+
+      +-----------------------------------------------------------------+
+      |                      TRANSCRIBER'S NOTES                        |
+      |                                                                 |
+      | Transcription used for this e-text:                             |
+      |   Italic text in the original work is transcribed between       |
+      |   underscores, as in _text_;                                    |
+      |   Bold face text in the original work is transcribed between    |
+      |   equal signs, as in =text=;                                    |
+      |   Bold face underlined text in the original work is transcribed |
+      |   between tildes, as in ~text~;                                 |
+      |   Super- and subscripts in the original work are transcribed as |
+      |   ^{text} and _{text}, respectively;                            |
+      |   Greek characters have been transcribed as [alpha], [beta],    |
+      |   etc.;                                                         |
+      |   The oe-ligature in Phoenix has been transcribed as oe.        |
+      |                                                                 |
+      | Some in-line multi-line formulas have been transcribed as       |
+      | single-line formulas, where necessary with brackets added.      |
+      |                                                                 |
+      | Some table headings have been replaced by legends [A], [B], etc;|
+      | these are listed directly above the relevant tables.            |
+      |                                                                 |
+      | More extensive Transcriber's Notes may be found at the end of   |
+      | this text.                                                      |
+      +-----------------------------------------------------------------+
+
+
+
+
+
+AVIATION ENGINES
+
+Design--Construction--Operation and Repair
+
+by
+
+FIRST LIEUT. VICTOR W. PAGÉ, A. S. S. C., U. S. R.
+
+
+      *      *      *      *      *
+
+
+~JUST PUBLISHED~
+
+
+=AVIATION ENGINES. Their Design, Construction, Operation and Repair.=
+
+    By Lieut. VICTOR W. PAGÉ, Aviation Section, S.C.U.S.R.
+
+    A practical work containing valuable instructions for aviation
+    students, mechanicians, squadron engineering officers and all
+    interested in the construction and upkeep of airplane power
+    plants. 576 octavo pages. 250 illustrations. Price $3.00.
+
+
+=AVIATION CHART, or the Location of Airplane Power Plant Troubles Made
+Easy.=
+
+    By Lieut. VICTOR W. PAGÉ, A.S., S.C.U.S.R.
+
+    A large chart outlining all parts of a typical airplane power
+    plant, showing the points where trouble is apt to occur and
+    suggesting remedies for the common defects. Intended especially
+    for aviators and aviation mechanics on school and field duty.
+    Price 50 cents.
+
+
+=GLOSSARY OF AVIATION TERMS.=
+
+    Compiled by Lieuts. VICTOR W. PAGÉ, A.S., S.C.U.S.R. and PAUL
+    MONTARIOL of the French Flying Corps on duty at Signal Corps
+    Aviation School, Mineola, L. I.
+
+    A complete glossary of practically all terms used in aviation,
+    having lists in both French and English, with equivalents in
+    either language. A very valuable book for all who are about to
+    leave for duty overseas. Price, cloth, $1.00.
+
+
+=THE NORMAN W. HENLEY PUBLISHING COMPANY=
+
+2 WEST 45TH ST., NEW YORK
+
+      *      *      *      *      *
+
+
+[Illustration: Part Sectional View of Hall-Scott Airplane Motor, Showing
+Principal Parts.]
+
+
+      *      *      *      *      *
+
+CENSORED
+
+This Book Entitled
+
+AVIATION ENGINES
+
+By LIEUT. VICTOR W. PAGÉ
+
+has been censored by the United States Government, and pages and
+parts of pages have been omitted by special instructions from
+Washington.
+
+The book has been passed by THE COMMITTEE ON PUBLIC INFORMATION
+and is as complete as we can furnish it, and we so advise the
+purchaser of it.
+
+THE NORMAN W. HENLEY PUBLISHING COMPANY
+
+
+      *      *      *      *      *
+
+
+AVIATION ENGINES
+
+Design--Construction--Operation and Repair
+
+A Complete, Practical Treatise Outlining Clearly
+the Elements of Internal Combustion Engineering
+with Special Reference to the Design, Construction,
+Operation and Repair of Airplane Power
+Plants; Also the Auxiliary Engine Systems, Such
+as Lubrication, Carburetion, Ignition and Cooling.
+
+It Includes Complete Instructions for Engine
+Repairing and Systematic Location of Troubles,
+Tool Equipment and Use of Tools, Also Outlines
+the Latest Mechanical Processes.
+
+by
+
+FIRST LIEUT. VICTOR W. PAGÉ, A. S. S. C., U. S. R.
+
+Assistant Engineering Officer, Signal Corps Aviation School,
+Mineola, L. I.
+
+Author of "The Modern Gasoline Automobile," Etc.
+
+[Illustration]
+
+Contains Valuable Instructions for All Aviation Students,
+Mechanicians, Squadron Engineering Officers and All Interested in
+the Construction and Upkeep of Airplane Power Plants.
+
+
+
+
+
+
+
+New York
+The Norman W. Henley Publishing Company
+2 West 45th Street
+1917
+
+Copyrighted, 1917
+By
+The Norman W. Henley Publishing Co.
+
+Printed in U. S. A.
+
+All Illustrations in This Book Have Been
+Specially Made by the Publishers, and Their
+Use, Without Permission, Is Strictly Prohibited
+
+Composition, Electrotyping and Presswork
+by the Publishers Printing Co., New York
+
+
+
+
+PREFACE
+
+
+In presenting this treatise on "Aviation Engines," the writer realizes
+that the rapidly developing art makes it difficult to outline all latest
+forms or describe all current engineering practice. This exposition has
+been prepared primarily for instruction purposes and is adapted for men
+in the Aviation Section, Signal Corps, and students who wish to become
+aviators or aviation mechanicians. Every effort has been made to have
+the engineering information accurate, but owing to the diversity of
+authorities consulted and use of data translated from foreign language
+periodicals, it is expected that some slight errors will be present. The
+writer wishes to acknowledge his indebtedness to such firms as the
+Curtiss Aeroplane and Motor Co., Hall-Scott Company, Thomas-Morse
+Aircraft Corporation and General Vehicle Company for photographs and
+helpful descriptive matter. Special attention has been paid to
+instructions on tool equipment, use of tools, trouble "shooting" and
+engine repairs, as it is on these points that the average aviation
+student is weakest. Only such theoretical consideration of
+thermo-dynamics as was deemed absolutely necessary to secure a proper
+understanding of engine action after consulting several instructors is
+included, the writer's efforts having been confined to the preparation
+of a practical series of instructions that would be of the greatest
+value to those who need a diversified knowledge of internal-combustion
+engine operation and repair, and who must acquire it quickly. The
+engines described and illustrated are all practical forms that have been
+fitted to airplanes capable of making flights and may be considered
+fairly representative of the present state of the art.
+
+VICTOR W. PAGÉ,
+
+_1st Lieut. A. S. S. C., U. S. R_.
+
+MINEOLA, L. I.,
+
+October, 1917.
+
+
+
+
+CONTENTS
+
+
+                                                                   PAGES
+  CHAPTER I
+
+  Brief Consideration of Aircraft Types--Essential Requirements of
+  Aerial Motors--Aviation Engines Must Be Light--Factors Influencing
+  Power Needed--Why Explosive Motors Are Best--Historical--Main
+  Types of Internal Combustion Engines                             17-36
+
+  CHAPTER II
+
+  Operating Principles of Two- and Four-Stroke Engines--Four-cycle
+  Action--Two-cycle Action--Comparing Two- and Four-cycle Types--
+  Theory of Gas and Gasoline Engine--Early Gas-Engine Forms--
+  Isothermal Law--Adiabatic Law--Temperature Computations--Heat and
+  Its Work--Conversion of Heat to Power--Requisites for Best Power
+  Effect                                                           37-59
+
+  CHAPTER III
+
+  Efficiency of Internal Combustion Engines--Various Measures of
+  Efficiency--Temperatures and Pressures--Factors Governing Economy
+  --Losses in Wall Cooling--Value of Indicator Cards--Compression in
+  Explosive Motors--Factors Limiting Compression--Causes of Heat
+  Losses and Inefficiency--Heat Losses to Cooling Water            60-79
+
+  CHAPTER IV
+
+  Engine Parts and Functions--Why Multiple Cylinder Engines Are Best
+  --Describing Sequence of Operations--Simple Engines--Four and Six
+  Cylinder Vertical Tandem Engines--Eight and Twelve Cylinder V
+  Engines--Radial Cylinder Arrangement--Rotary Cylinder Forms     80-109
+
+  CHAPTER V
+
+  Properties of Liquid Fuels--Distillates of Crude Petroleum--
+  Principles of Carburetion Outlined--Air Needed to Burn Gasoline--
+  What a Carburetor Should Do--Liquid Fuel Storage and Supply--
+  Vacuum Fuel Feed--Early Vaporizer Forms--Development of Float Feed
+  Carburetor--Maybach's Early Design--Concentric Float and Jet Type
+  --Schebler Carburetor--Claudel Carburetor--Stewart Metering Pin
+  Type--Multiple Nozzle Vaporizers--Two-Stage Carburetor--Master
+  Multiple Jet Type--Compound Nozzle Zenith Carburetor--Utility of
+  Gasoline Strainers--Intake Manifold Design and Construction--
+  Compensating for Various Atmospheric Conditions--How High
+  Altitude Affects Power--The Diesel System--Notes on Carburetor
+  Installation--Notes on Carburetor Adjustment                   110-154
+
+  CHAPTER VI
+
+  Early Ignition Systems--Electrical Ignition Best--Fundamentals of
+  Magnetism Outlined--Forms of Magneto--Zones of Magnetic Influence
+  --How Magnets are Made--Electricity and Magnetism Related--Basic
+  Principles of Magneto Action--Essential Parts of Magneto and
+  Functions--Transformer Coil Systems--True High Tension Type--The
+  Berling Magneto--Timing and Care--The Dixie Magneto--Spark-Plug
+  Design and Application--Two-Spark Ignition--Special Airplane
+  Plug                                                           155-200
+
+  CHAPTER VII
+
+  Why Lubrication Is Necessary--Friction Defined--Theory of
+  Lubrication--Derivation of Lubricants--Properties of Cylinder Oils
+  --Factors Influencing Lubrication System Selection--Gnome Type
+  Engines Use Castor Oil--Hall-Scott Lubrication System--Oil Supply
+  by Constant Level Splash System--Dry Crank-Case System Best for
+  Airplane Engines--Why Cooling Systems Are Necessary--Cooling
+  Systems Generally Applied--Cooling by Positive Pump Circulation--
+  Thermo-Syphon System--Direct Air-Cooling Methods--Air-Cooled
+  Engine Design Considerations                                   201-232
+
+  CHAPTER VIII
+
+  Methods of Cylinder Construction--Block Castings--Influence on
+  Crank-Shaft Design--Combustion Chamber Design--Bore and Stroke
+  Ratio--Meaning of Piston Speed--Advantage of Off-Set Cylinders--
+  Valve Location of Vital Import--Valve Installation Practice--Valve
+  Design and Construction--Valve Operation--Methods of Driving
+  Cam-Shaft--Valve Springs--Valve Timing--Blowing Back--Lead Given
+  Exhaust Valve--Exhaust Closing, Inlet Opening--Closing the
+  Inlet Valve--Time of Ignition--How an Engine is Timed--Gnome
+  "Monosoupape" Valve Timing--Springless Valves--Four Valves per
+  Cylinder                                                       233-286
+
+  CHAPTER IX
+
+  Constructional Details of Pistons--Aluminum Cylinders and Pistons
+  --Piston Ring Construction--Leak Proof Piston Rings--Keeping Oil
+  Out of Combustion Chamber--Connecting Rod Forms--Connecting Rods
+  for Vee Engines--Cam-Shaft and Crank-Shaft Designs--Ball Bearing
+  Crank-Shafts--Engine Base Construction                         287-323
+
+  CHAPTER X
+
+  Power Plant Installation--Curtiss OX-2 Engine Mounting and
+  Operating Rules--Standard S. A. E. Engine Bed Dimensions--
+  Hall-Scott Engine Installation and Operation--Fuel System Rules
+  --Ignition System--Water System--Preparations to Start Engine--
+  Mounting Radial and Rotary Engines--Practical Hints to Locate
+  Engine Troubles--All Engine Troubles Summarized--Location of
+  Engine Troubles Made Easy                                      324-375
+
+  CHAPTER XI
+
+  Tools for Adjusting and Erecting--Forms of Wrenches--Use and Care
+  of Files--Split Pin Removal and Installation--Complete Chisel Set
+  --Drilling Machines--Drills, Reamers, Taps and Dies--Measuring
+  Tools--Micrometer Calipers and Their Use--Typical Tool Outfits
+  --Special Hall-Scott Tools--Overhauling Airplane Engines--Taking
+  Engine Down--Defects in Cylinders--Carbon Deposits, Cause and
+  Prevention--Use of Carbon Scrapers--Burning Out Carbon with
+  Oxygen --Repairing Scored Cylinders--Valve Removal and Inspection
+  --Reseating and Truing Valves--Valve Grinding Processes--
+  Depreciation in Valve Operating System--Piston Troubles--Piston
+  Ring Manipulation--Fitting Piston Rings--Wrist-Pin Wear--
+  Inspection and Refitting of Engine Bearings--Scraping Brasses to
+  Fit--Fitting Connecting Rods--Testing for Bearing Parallelism--
+  Cam-Shafts and Timing Gears--Precautions in Reassembling Parts 376-456
+
+  CHAPTER XII
+
+  Aviation Engine Types--Division in Classes--Anzani Engines--Canton
+  and Unné Engine--Construction of Gnome Engines--"Monosoupape"
+  Gnome--German "Gnome" Type--Le Rhone Engine--Renault Air-Cooled
+  Engine--Simplex Model "A" Hispano-Suiza--Curtiss Aviation Motors--
+  Thomas-Morse Model 88 Engine--Duesenberg Engine--Aeromarine
+  Six-Cylinder--Wisconsin Aviation Engines--Hall-Scott Engines--
+  Mercedes Motor--Benz Motor--Austro-Daimler Engine--Sunbeam-Coatalen
+  --Indicating and Measuring Instruments--Air Starting Systems--
+  Electric Starting--Battery Ignition                            457-571
+
+  INDEX                                                              573
+
+  LIST OF ILLUSTRATIONS
+
+
+
+
+AVIATION ENGINES
+
+DESIGN--CONSTRUCTION--REPAIR
+
+
+
+
+CHAPTER I
+
+    Brief Consideration of Aircraft Types--Essential Requirements of
+    Aerial Motors--Aviation Engines Must Be Light--Factors
+    Influencing Power Needed--Why Explosive Motors Are Best--
+    Historical--Main Types of Internal Combustion Engines.
+
+
+BRIEF CONSIDERATION OF AIRCRAFT TYPES
+
+The conquest of the air is one of the most stupendous achievements of
+the ages. Human flight opens the sky to man as a new road, and because
+it is a road free of all obstructions and leads everywhere, affording
+the shortest distance to any place, it offers to man the prospect of
+unlimited freedom. The aircraft promises to span continents like
+railroads, to bridge seas like ships, to go over mountains and forests
+like birds, and to quicken and simplify the problems of transportation.
+While the actual conquest of the air is an accomplishment just being
+realized in our days, the idea and yearning to conquer the air are old,
+possibly as old as intellect itself. The myths of different races tell
+of winged gods and flying men, and show that for ages to fly was the
+highest conception of the sublime. No other agent is more responsible
+for sustained flight than the internal combustion motor, and it was only
+when this form of prime mover had been fully developed that it was
+possible for man to leave the ground and alight at will, not depending
+upon the caprices of the winds or lifting power of gases as with the
+balloon. It is safe to say that the solution of the problem of flight
+would have been attained many years ago if the proper source of power
+had been available as all the essential elements of the modern
+aeroplane and dirigible balloon, other than the power plant, were known
+to early philosophers and scientists.
+
+Aeronautics is divided into two fundamentally different
+branches--aviatics and aerostatics. The first comprises all types of
+aeroplanes and heavier than air flying machines such as the helicopters,
+kites, etc.; the second includes dirigible balloons, passive balloons
+and all craft which rise in the air by utilizing the lifting force of
+gases. Aeroplanes are the only practical form of heavier-than-air
+machines, as the helicopters (machines intended to be lifted directly
+into the air by propellers, without the sustaining effect of planes),
+and ornithopters, or flapping wing types, have not been thoroughly
+developed, and in fact, there are so many serious mechanical problems to
+be solved before either of these types of air craft will function
+properly that experts express grave doubts regarding the practicability
+of either. Aeroplanes are divided into two main types--monoplanes or
+single surface forms, and bi-planes or machines having two sets of
+lifting surfaces, one suspended over the other. A third type, the
+triplane, is not very widely used.
+
+Dirigible balloons are divided into three classes: the rigid, the
+semi-rigid, and the non-rigid. The rigid has a frame or skeleton of
+either wood or metal inside of the bag, to stiffen it; the semi-rigid is
+reinforced by a wire net and metal attachments; while the non-rigid is
+just a bag filled with gas. The aeroplane, more than the dirigible and
+balloon, stands as the emblem of the conquest of the air. Two reasons
+for this are that power flight is a real conquest of the air, a real
+victory over the battling elements; secondly, because the aeroplane, or
+any flying machine that may follow, brings air travel within the reach
+of everybody. In practical development, the dirigible may be the
+steamship of the air, which will render invaluable services of a certain
+kind, and the aeroplane will be the automobile of the air, to be used by
+the multitude, perhaps for as many purposes as the automobile is now
+being used.
+
+
+ESSENTIAL REQUIREMENTS OF AERIAL MOTORS
+
+One of the marked features of aircraft development has been the effect
+it has had upon the refinement and perfection of the internal combustion
+motor. Without question gasoline-motors intended for aircraft are the
+nearest to perfection of any other type yet evolved. Because of the
+peculiar demands imposed upon the aeronautical motor it must possess all
+the features of reliability, economy and efficiency now present with
+automobile or marine engines and then must have distinctive points of
+its own. Owing to the unstable nature of the medium through which it is
+operated and the fact that heavier-than-air machines can maintain flight
+only as long as the power plant is functioning properly, an airship
+motor must be more reliable than any used on either land or water. While
+a few pounds of metal more or less makes practically no difference in a
+marine motor and has very little effect upon the speed or hill-climbing
+ability of an automobile, an airship motor must be as light as it is
+possible to make it because every pound counts, whether the motor is to
+be fitted into an aeroplane or in a dirigible balloon.
+
+Airship motors, as a rule, must operate constantly at high speeds in
+order to obtain a maximum power delivery with a minimum piston
+displacement. In automobiles, or motor boats, motors are not required to
+run constantly at their maximum speed. Most aircraft motors must
+function for extended periods at speed as nearly the maximum as
+possible. Another thing that militates against the aircraft motor is the
+more or less unsteady foundation to which it is attached. The
+necessarily light framework of the aeroplane makes it hard for a motor
+to perform at maximum efficiency on account of the vibration of its
+foundation while the craft is in flight. Marine and motor car engines,
+while not placed on foundations as firm as those provided for stationary
+power plants, are installed on bases of much more stability than the
+light structure of an aeroplane. The aircraft motor, therefore, must be
+balanced to a nicety and must run steadily under the most unfavorable
+conditions.
+
+
+AERIAL MOTORS MUST BE LIGHT
+
+The capacity of light motors designed for aerial work per unit of mass
+is surprising to those not fully conversant with the possibilities that
+a thorough knowledge of proportions of parts and the use of special
+metals developed by the automobile industry make possible. Activity in
+the development of light motors has been more pronounced in France than
+in any other country. Some of these motors have been complicated types
+made light by the skillful proportioning of parts, others are of the
+refined simpler form modified from current automobile practice. There is
+a tendency to depart from the freakish or unconventional construction
+and to adhere more closely to standard forms because it is necessary to
+have the parts of such size that every quality making for reliability,
+efficiency and endurance are incorporated in the design. Aeroplane
+motors range from two cylinders to forms having fourteen and sixteen
+cylinders and the arrangement of these members varies from the
+conventional vertical tandem and opposed placing to the V form or the
+more unusual radial motors having either fixed or rotary cylinders. The
+weight has been reduced so it is possible to obtain a complete power
+plant of the revolving cylinder air-cooled type that will not weigh more
+than three pounds per actual horse-power and in some cases less than
+this.
+
+If we give brief consideration to the requirements of the aviator it
+will be evident that one of the most important is securing maximum power
+with minimum mass, and it is desirable to conserve all of the good
+qualities existing in standard automobile motors. These are certainty of
+operation, good mechanical balance and uniform delivery of
+power--fundamental conditions which must be attained before a power
+plant can be considered practical. There are in addition, secondary
+considerations, none the less desirable, if not absolutely essential.
+These are minimum consumption of fuel and lubricating oil, which is
+really a factor of import, for upon the economy depends the capacity and
+flying radius. As the amount of liquid fuel must be limited the most
+suitable motor will be that which is powerful and at the same time
+economical. Another important feature is to secure accessibility of
+components in order to make easy repair or adjustment of parts possible.
+It is possible to obtain sufficiently light-weight motors without
+radical departure from established practice. Water-cooled power plants
+have been designed that will weigh but four or five pounds per
+horse-power and in these forms we have a practical power plant capable
+of extended operation.
+
+
+FACTORS INFLUENCING POWER NEEDED
+
+Work is performed whenever an object is moved against a resistance, and
+the amount of work performed depends not only on the amount of
+resistance overcome but also upon the amount of time utilized in
+accomplishing a given task. Work is measured in horse-power for
+convenience. It will take one horse-power to move 33,000 pounds one foot
+in one minute or 550 pounds one foot in one second. The same work would
+be done if 330 pounds were moved 100 feet in one minute. It requires a
+definite amount of power to move a vehicle over the ground at a certain
+speed, so it must take power to overcome resistance of an airplane in
+the air. Disregarding the factor of air density, it will take more power
+as the speed increases if the weight or resistance remains constant, or
+more power if the speed remains constant and the resistance increases.
+The airplane is supported by air reaction under the planes or lifting
+surfaces and the value of this reaction depends upon the shape of the
+aerofoil, the amount it is tilted and the speed at which it is drawn
+through the air. The angle of incidence or degree of wing tilt regulates
+the power required to a certain degree as this affects the speed of
+horizontal flight as well as the resistance. Resistance may be of two
+kinds, one that is necessary and the other that it is desirable to
+reduce to the lowest point possible. There is the wing resistance and
+the sum of the resistances of the rest of the machine such as fuselage,
+struts, wires, landing gear, etc. If we assume that a certain airplane
+offered a total resistance of 300 pounds and we wished to drive it
+through the air at a speed of sixty miles per hour, we can find the
+horse-power needed by a very simple computation as follows:
+
+   The product of 300 pounds resistance times speed of
+     88 feet per second times 60 seconds in a minute
+  ----------------------------------------------------- = H.P. needed.
+        divided by 33,000 foot pounds per minute
+                  in one horse-power
+
+The result is the horse-power needed, or
+
+   300 × 88 × 60
+  --------------- = 48 H.P.
+      33,000
+
+Just as it takes more power to climb a hill than it does to run a car on
+the level, it takes more power to climb in the air with an airplane than
+it does to fly on the level. The more rapid the climb, the more power it
+will take. If the resistance remains 300 pounds and it is necessary to
+drive the plane at 90 miles per hour, we merely substitute proper values
+in the above formula and we have
+
+   300 pounds times 132 feet per second times 60
+               seconds in a minute
+  ----------------------------------------------- = 72 H.P.
+       33,000 foot pounds per minute in one
+                  horse-power
+
+The same results can be obtained by dividing the product of the
+resistance in pounds times speed in feet per second by 550, which is the
+foot-pounds of work done in one second to equal one horse-power.
+Naturally, the amount of propeller thrust measured in pounds necessary
+to drive an airplane must be greater than the resistance by a
+substantial margin if the plane is to fly and climb as well. The
+following formulæ were given in "The Aeroplane" of London and can be
+used to advantage by those desiring to make computations to ascertain
+power requirements:
+
+[Illustration: Fig. 1.--Diagrams Illustrating Computations for
+Horse-Power Required for Airplane Flight.]
+
+The thrust of the propeller depends on the power of the motor, and on
+the diameter and pitch of the propeller. If the required thrust to a
+certain machine is known, the calculation for the horse-power of the
+motor should be an easy matter.
+
+The required thrust is the sum of three different "resistances." The
+first is the "drift" (dynamical head resistance of the aerofoils), i.e.,
+tan [alpha] × lift (_L_), lift being equal to the total weight of
+machine (_W_) for horizontal flight and [alpha] equal to the angle of
+incidence. Certainly we must take the tan [alpha] at the maximum _K_{y}_
+value for minimum speed, as then the drift is the greatest (Fig. 1, A).
+
+Another method for finding the drift is _D_ = _K_ × _AV_^{2}, when we
+take the drift again so as to be greatest.
+
+The second "resistance" is the total head resistance of the machine, at
+its maximum velocity. And the third is the thrust for climbing. The
+horse-power for climbing can be found out in two different ways. I first
+propose to deal with the method, where we find out the actual
+horse-power wanted for a certain climbing speed to our machine, where
+
+          climbing speed/sec. × _W_
+  H.P. = ---------------------------
+                     550
+
+In this case we know already the horse-power for climbing, and we can
+proceed with our calculation.
+
+With the other method we shall find out the "thrust" in pounds or
+kilograms wanted for climbing and add it to drift and total head
+resistance, and we shall have the total "thrust" of our machine and we
+shall denote it with _T_, while thrust for climbing shall be _T_{c}_.
+
+The following calculation is at our service to find out
+
+                            _V_{c}_ × _W_
+  this thrust for climbing --------------- = H.P.,
+                                 550
+
+                    H.P. × 550
+  thence _V_{c}_ = ------------                                      (1)
+                       _W_
+
+          _T_{c}_ × _V_
+  H.P. = --------------, then from
+               550
+
+                  _T_{c}_ × _V_
+                 --------------- × 550
+                      550                  _T_{c}_ × _V_
+  (1) _V_{c}_ = ----------------------- = ---------------, thence,
+                         _W_                    _W_
+
+           _V_{c}_ × _W_
+  T_{c} = ---------------.
+               _V_
+
+Whether _T_ means drifts, head resistance and thrust for climbing, or
+drift and head resistance only, the following calculation is the same,
+only in the latter case, of course, we must add the horse-power required
+for climbing to the result to obtain the total horse-power.
+
+Now, when we know the total thrust, we shall find the horse-power in the
+following manner:
+
+                           _Pr_2[pi]_R_
+  We know that the H.P. = -------------- in kilograms, or in
+                               75 × 60
+
+                           _Pr_2[pi]_R_
+  English measure, H.P. = -------------- (Fig. 1, B)
+                              33,000
+
+  where _P_ = pressure in klgs. or lbs.
+        _r_ = radius on which _P_ is acting.
+        _R_ = Revolution/min.
+
+                                     _M.R._2[pi]
+  When _P_ × _r_ = _M_, then H.P. = -------------, thence,
+                                        4,500
+
+         H.P. × 4,500     716.2 H.P.
+  _M_ = -------------- = ------------ in meter kilograms,
+           _R_2[pi]          _R_
+
+                              H.P. 33,000     5253.1 H.P.
+  or in English system _M_ = ------------- = ------------- in
+                               _R_2[pi]           _R_
+
+foot pounds.
+
+Now the power on the circumference of the propeller will be reduced by
+its radius, so it will be _M_/_r_ = _p_. A part of _p_ will be used for
+counteracting the air and bearing friction, so that the total power on
+the circumference of the propeller will be (_M_/_r_) × [eta] = _p_ where
+[eta] is the mechanical efficiency of the propeller. Now
+
+       [eta]
+  --------------- = _T_, where [alpha] is taken on the tip of the
+   _tan_ [alpha]
+
+propeller.
+
+I take [alpha] at the tip, but it can be taken, of course, at any point,
+but then in equation _p_ = _M_/_r_, _r_ must be taken only up to this
+point, and not the whole radius; but it is more comfortable to take it
+at the tip, as
+
+                    Pitch
+  _tan_ [alpha] = ---------- (Fig. 1, C).
+                   _r_2[pi]
+
+Now we can write up the equation of the thrust:
+
+   716.2 H.P. [eta]                           5253.1 H.P. [eta]
+  -------------------, or in English measure -------------------
+   _R r tan [alpha]_                          _R r tan [alpha]_
+
+                 _T_ × _R_ × _r tan_ [alpha]
+  thence H.P. = -----------------------------, or in English measure
+                       716.2[eta]
+
+   _T_ × _R_ × _r tan_ [alpha]
+  -----------------------------.
+          5253.1[eta]
+
+The computations and formulæ given are of most value to the student
+engineer rather than matters of general interest, but are given so that
+a general idea may be secured of how airplane design influences power
+needed to secure sustained flight. It will be apparent that the
+resistance of an airplane depends upon numerous considerations of design
+which require considerable research in aerodynamics to determine
+accurately. It is obvious that the more resistance there is, the more
+power needed to fly at a given speed. Light monoplanes have been flown
+with as little as 15 horse-power for short distances, but most planes
+now built use engines of 100 horse-power or more. Giant airplanes have
+been constructed having 2,000 horse-power distributed in four power
+units. The amount of power provided for an airplane of given design
+varies widely as many conditions govern this, but it will range from
+approximately one horse-power to each 8 pounds weight in the case of
+very light, fast machines to one horse-power to 15 or 18 pounds of the
+total weight in the case of medium speed machines. The development in
+airplane and power plant design is so rapid, however, that the figures
+given can be considered only in the light of general averages rather
+than being typical of current practice.
+
+
+WHY EXPLOSIVE MOTORS ARE BEST
+
+Internal combustion engines are best for airplanes and all types of
+aircraft for the same reasons that they are universally used as a source
+of power for automobiles. The gasoline engine is the lightest known form
+of prime mover and a more efficient one than a steam engine, especially
+in the small powers used for airplane propulsion. It has been stated
+that by very careful designing a steam plant an engine could be made
+that would be practical for airplane propulsion, but even with the
+latest development it is doubtful if steam power can be utilized in
+aircraft to as good advantage as modern gasoline-engines are. While the
+steam-engine is considered very much simpler than a gas-motor, the
+latter is much more easily mastered by the non-technical aviator and
+certainly requires less attention. A weight of 10 pounds per horse-power
+is possible in a condensing steam plant but this figure is nearly double
+or triple what is easily secured with a gas-motor which may weigh but 5
+pounds per horse-power in the water cooled forms and but 2 or 3 pounds
+in the air-cooled types. The fuel consumption is twice as great in a
+steam-power plant (owing to heat losses) as would be the case in a
+gasoline engine of equal power and much less weight.
+
+The internal-combustion engine has come seemingly like an avalanche of a
+decade; but it has come to stay, to take its well-deserved position
+among the powers for aiding labor. Its ready adaptation to road, aerial
+and marine service has made it a wonder of the age in the development of
+speed not before dreamed of as a possibility; yet in so short a time,
+its power for speed has taken rank on the common road against the
+locomotive on the rail with its century's progress. It has made aerial
+navigation possible and practical, it furnishes power for all marine
+craft from the light canoe to the transatlantic liner. It operates the
+machine tools of the mechanic, tills the soil for the farmer and
+provides healthful recreation for thousands by furnishing an economical
+means of transport by land and sea. It has been a universal mechanical
+education for the masses, and in its present forms represents the great
+refinement and development made possible by the concentration of the
+world's master minds on the problems incidental to internal combustion
+engineering.
+
+
+HISTORICAL
+
+Although the ideal principle of explosive power was conceived some two
+hundred years ago, at which time experiments were made with gunpowder as
+the explosive element, it was not until the last years of the eighteenth
+century that the idea took a patentable shape, and not until about 1826
+(Brown's gas-vacuum engine) that a further progress was made in England
+by condensing the products of combustion by a jet of water, thus
+creating a partial vacuum.
+
+Brown's was probably the first explosive engine that did real work. It
+was clumsy and unwieldy and was soon relegated to its place among the
+failures of previous experiments. No approach to active explosive effect
+in a cylinder was reached in practice, although many ingenious designs
+were described, until about 1838 and the following years. Barnett's
+engine in England was the first attempt to compress the charge before
+exploding. From this time on to about 1860 many patents were issued in
+Europe and a few in the United States for gas-engines, but the progress
+was slow, and its practical introduction for power came with spasmodic
+effect and low efficiency. From 1860 on, practical improvement seems to
+have been made, and the Lenoir motor was produced in France and brought
+to the United States. It failed to meet expectations, and was soon
+followed by further improvements in the Hugon motor in France (1862),
+followed by Beau de Rocha's four-cycle idea, which has been slowly
+developed through a long series of experimental trials by different
+inventors. In the hands of Otto and Langdon a further progress was made,
+and numerous patents were issued in England, France, and Germany, and
+followed up by an increasing interest in the United States, with a few
+patents.
+
+From 1870 improvements seem to have advanced at a steady rate, and
+largely in the valve-gear and precision of governing for variable load.
+The early idea of the necessity of slow combustion was a great drawback
+in the advancement of efficiency, and the suggestion of de Rocha in 1862
+did not take root as a prophetic truth until many failures and years of
+experience had taught the fundamental axiom that rapidity of action in
+both combustion and expansion was the basis of success in explosive
+motors.
+
+With this truth and the demand for small and safe prime movers, the
+manufacture of gas-engines increased in Europe and America at a more
+rapid rate, and improvements in perfecting the details of this cheap and
+efficient prime mover have finally raised it to the dignity of a
+standard motor and a dangerous rival of the steam-engine for small and
+intermediate powers, with a prospect of largely increasing its
+individual units to many hundred, if not to the thousand horse-power in
+a single cylinder. The unit size in a single cylinder has now reached to
+about 700 horse-power and by combining cylinders in the same machine,
+powers of from 1,500 to 2,000 horse-power are now available for large
+power-plants.
+
+
+MAIN TYPES OF INTERNAL-COMBUSTION ENGINES
+
+This form of prime mover has been built in so many different types, all
+of which have operated with some degree of success that the diversity in
+form will not be generally appreciated unless some attempt is made to
+classify the various designs that have received practical application.
+Obviously the same type of engine is not universally applicable, because
+each class of work has individual peculiarities which can best be met by
+an engine designed with the peculiar conditions present in view. The
+following tabular synopsis will enable the reader to judge the extent of
+the development of what is now the most popular prime mover for all
+purposes.
+
+  A.  Internal Combustion (Standard Type)
+        1. Single Acting (Standard Type)
+        2. Double Acting (For Large Power Only)
+        3. Simple (Universal Form)
+        4. Compound (Rarely Used)
+        5. Reciprocating Piston (Standard Type)
+        6. Turbine (Revolving Rotor, not fully developed)
+
+  A1. Two-Stroke Cycle
+        a. Two Port
+        b. Three Port
+        c. Combined Two and Three Port
+        d. Fourth Port Accelerator
+        e. Differential Piston Type
+        f. Distributor Valve System
+
+  A2. Four-Stroke Cycle
+        a. Automatic Inlet Valve
+        b. Mechanical Inlet Valve
+        c. Poppet or Mushroom Valve
+        d. Slide Valve
+             d 1. Sleeve Valve
+             d 2. Reciprocating Ring Valve
+             d 3. Piston Valve
+        e. Rotary Valves
+             e 1. Disc
+             e 2. Cylinder or Barrel
+             e 3. Single Cone
+             e 4. Double Cone
+        f. Two Piston (Balanced Explosion)
+        g. Rotary Cylinder, Fixed Crank (Aerial)
+        h. Fixed Cylinder, Rotary Crank (Standard Type)
+
+  A3. Six-Stroke Cycle
+
+  B.  External Combustion (Practically Obsolete)
+        a. Turbine, Revolving Rotor
+        b. Reciprocating Piston
+
+
+CLASSIFICATION BY CYLINDER ARRANGEMENT
+
+  Single Cylinder
+    a. Vertical
+    b. Horizontal
+    c. Inverted Vertical
+
+  Double Cylinder
+    a. Vertical
+    b. Horizontal (Side by Side)
+    c. Horizontal (Opposed)
+    d. 45 to 90 Degrees V (Angularly Disposed)
+    e. Horizontal Tandem (Double Acting)
+
+  Three Cylinder
+    a. Vertical
+    b. Horizontal
+    c. Rotary (Cylinders Spaced at 120 Degrees)
+    d. Radially Placed (Stationary Cylinders)
+    e. One Vertical, One Each Side at an Angle
+    f. Compound (Two High Pressure, One Low Pressure)
+
+  Four Cylinder
+    a. Vertical
+    b. Horizontal (Side by Side)
+    c. Horizontal (Two Pairs Opposed)
+    d. 45 to 90 Degrees V
+    e. Twin Tandem (Double Acting)
+
+  Five Cylinder
+    a. Vertical (Five Throw Crankshaft)
+    b. Radially Spaced at 72 Degrees (Stationary)
+    c. Radially Placed Above Crankshaft (Stationary)
+    d. Placed Around Rotary Crankcase (72 Degrees Spacing)
+
+  Six Cylinder
+    a. Vertical
+    b. Horizontal (Three Pairs Opposed)
+    c. 45 to 90 Degrees V
+
+  Seven Cylinder
+    a. Equally Spaced (Rotary)
+
+  Eight Cylinder
+    a. Vertical
+    b. Horizontal (Four Pairs Opposed)
+    c. 45 to 90 Degrees V
+
+  Nine Cylinder
+    a. Equally Spaced (Rotary)
+
+  Twelve Cylinder
+    a. Vertical
+    b. Horizontal (Six Pairs Opposed)
+    c. 45 to 90 Degrees V
+
+  Fourteen Cylinder
+    a. Rotary
+
+  Sixteen Cylinder
+    a. 45 to 90 Degrees V
+    b. Horizontal (Eight Pairs Opposed)
+
+  Eighteen Cylinder
+    a. Rotary Cylinder
+
+[Illustration: Fig. 2.--Plate Showing Heavy, Slow Speed Internal
+Combustion Engines Used Only for Stationary Power in Large Installations
+Giving Weight to Horse-Power Ratio.]
+
+[Illustration: Fig. 3.--Various Forms of Internal Combustion Engines
+Showing Decrease in Weight to Horse-Power Ratio with Augmenting Speed of
+Rotation.]
+
+[Illustration: Fig. 4.--Internal Combustion Engine Types of Extremely
+Fine Construction and Refined Design, Showing Great Power Outputs for
+Very Small Weight, a Feature Very Much Desired in Airplane Power
+Plants.]
+
+Of all the types enumerated above engines having less than eight
+cylinders are the most popular in everything but aircraft work. The
+four-cylinder vertical is without doubt the most widely used of all
+types owing to the large number employed as automobile power plants.
+Stationary engines in small and medium powers are invariably of the
+single or double form. Three-cylinder engines are seldom used at the
+present time, except in marine work and in some stationary forms.
+Eight- and twelve-cylinder motors have received but limited application
+and practically always in automobiles, racing motor boats or in aircraft.
+The only example of a fourteen-cylinder motor to be used to any extent
+is incorporated in aeroplane construction. This is also true of the
+sixteen- and eighteen-cylinder forms and of twenty-four-cylinder engines
+now in process of development.
+
+The duty an engine is designed for determines the weight per
+horse-power. High powered engines intended for steady service are always
+of the slow speed type and consequently are of very massive
+construction. Various forms of heavy duty type stationary engines are
+shown at Fig. 2. Some of these engines may weigh as much as 600 pounds
+per horse-power. A further study is possible by consulting data given on
+Figs. 3 and 4. As the crank-shaft speed increases and cylinders are
+multiplied the engines become lighter. While the big stationary power
+plants may run for years without attention, airplane engines require
+rebuilding after about 60 to 80 hours air service for the fixed cylinder
+types and 40 hours or less for the rotary cylinder air-cooled forms.
+There is evidently a decrease in durability and reliability as the
+weight is lessened. These illustrations also permit of obtaining a good
+idea of the variety of forms internal combustion engines are made in.
+
+
+
+
+CHAPTER II
+
+    Operating Principles of Two- and Four-Stroke Engines--Four-cycle
+    Action--Two-cycle Action--Comparing Two- and Four-cycle Types--
+    Theory of Gas and Gasoline Engine--Early Gas-Engine Forms--
+    Isothermal Law--Adiabatic Law--Temperature Computations--Heat
+    and Its Work--Conversion of Heat to Power--Requisites for Best
+    Power Effect.
+
+
+OPERATING PRINCIPLES OF TWO- AND FOUR-STROKE CYCLE ENGINES
+
+Before discussing the construction of the various forms of internal
+combustion engines it may be well to describe the operating cycle of the
+types most generally used. The two-cycle engine is the simplest because
+there are no valves in connection with the cylinder, as the gas is
+introduced into that member and expelled from it through ports cored
+into the cylinder walls. These are covered by the piston at a certain
+portion of its travel and uncovered at other parts of its stroke. In the
+four-cycle engine the explosive gas is admitted to the cylinder through
+a port at the head end closed by a valve, while the exhaust gas is
+expelled through another port controlled in a similar manner. These
+valves are operated by mechanism distinct from the piston.
+
+[Illustration: Fig. 5.--Outlining First Two Strokes of Piston in
+Four-Cycle Engine.]
+
+The action of the four-cycle type may be easily understood if one refers
+to illustrations at Figs. 5 and 6. It is called the "four-stroke engine"
+because the piston must make four strokes in the cylinder for each
+explosion or power impulse obtained. The principle of the gas-engine of
+the internal combustion type is similar to that of a gun, i.e., power is
+obtained by the rapid combustion of some explosive or other quick
+burning substance. The bullet is driven out of the gun barrel by the
+pressure of the gas evolved when the charge of powder is ignited. The
+piston or movable element of the gas-engine is driven from the closed
+or head end to the crank end of the cylinder by a similar expansion of
+gases resulting from combustion. The first operation in firing a gun or
+securing an explosion in the cylinder of the gas-engine is to fill the
+combustion space with combustible material. This is done by a down
+stroke of the piston during which time the inlet valve opens to admit
+the gaseous charge to the cylinder interior. This operation is shown at
+Fig. 5, A. The second operation is to compress this gas which is done by
+an upward stroke of the piston as shown at Fig. 5, B. When the top of
+the compression stroke is reached, the gas is ignited and the piston is
+driven down toward the open end of the cylinder, as indicated at Fig. 6,
+C. The fourth operation or exhaust stroke is performed by the return
+upward movement of the piston as shown at Fig. 6, D during which time
+the exhaust valve is opened to permit the burnt gases to leave the
+cylinder. As soon as the piston reaches the top of its exhaust stroke,
+the energy stored in the fly-wheel rim during the power stroke causes
+that member to continue revolving and as the piston again travels on
+its down stroke the inlet valve opens and admits a charge of fresh gas
+and the cycle of operations is repeated.
+
+[Illustration: Fig. 6.--Outlining Second Two Strokes of Piston in
+Four-Cycle Engine.]
+
+[Illustration: Fig. 7.--Sectional View of L Head Gasoline Engine
+Cylinder Showing Piston Movements During Four-Stroke Cycle.]
+
+The illustrations at Fig. 7 show how the various cycle functions take
+place in an L head type water cooled cylinder engine. The sections at A
+and C are taken through the inlet valve, those at B and D are taken
+through the exhaust valve.
+
+The two-cycle engine works on a different principle, as while only the
+combustion chamber end of the piston is employed to do useful work in
+the four-cycle engine, both upper and lower portions are called upon to
+perform the functions necessary to two-cycle engine operation. Instead
+of the gas being admitted into the cylinder as is the case with the
+four-stroke engine, it is first drawn into the engine base where it
+receives a preliminary compression prior to its transfer to the working
+end of the cylinder. The views at Fig. 8 should indicate clearly the
+operation of the two-port two-cycle engine. At A the piston is seen
+reaching the top of its stroke and the gas above the piston is being
+compressed ready for ignition, while the suction in the engine base
+causes the automatic valve to open and admits mixture from the
+carburetor to the crank case. When the piston reaches the top of its
+stroke, the compressed gas is ignited and the piston is driven down on
+the power stroke, compressing the gas in the engine base.
+
+[Illustration: Fig. 8.--Showing Two-port, Two-cycle Engine Operation.]
+
+When the top of the piston uncovers the exhaust port the flaming gas
+escapes because of its pressure. A downward movement of the piston
+uncovers the inlet port opposite the exhaust and permits the fresh gas
+to bypass through the transfer passage from the engine base to the
+cylinder. The conditions with the intake and exhaust port fully opened
+are clearly shown at Fig. 8, C. The deflector plate on the top of the
+piston directs the entering fresh gas to the top of the cylinder and
+prevents the main portion of the gas stream from flowing out through the
+open exhaust port. On the next upstroke of the piston the gas in the
+cylinder is compressed and the inlet valve opened, as shown at A to
+permit a fresh charge to enter the engine base.
+
+[Illustration: Fig. 9.--Defining Three-port, Two-cycle Engine Action.]
+
+The operating principle of the three-port, two-cycle engine is
+practically the same as that previously described with the exception
+that the gas is admitted to the crank-case through a third port in the
+cylinder wall, which is uncovered by the piston when that member reaches
+the end of its upstroke. The action of the three-port form can be
+readily ascertained by studying the diagrams given at Fig. 9.
+Combination two- and three-port engines have been evolved and other
+modifications made to improve the action.
+
+
+THE TWO-CYCLE AND FOUR-CYCLE TYPES
+
+In the earlier years of explosive-motor progress was evolved the two
+types of motors in regard to the cycles of their operation. The early
+attempts to perfect the two-cycle principle were for many years held in
+abeyance from the pressure of interests in the four-cycle type, until
+its simplicity and power possibilities were demonstrated by Mr. Dugald
+Clerk in England, who gave the principles of the two-cycle motor a broad
+bearing leading to immediate improvements in design, which has made
+further progress in the United States, until at the present time it has
+an equal standard value as a motor-power in some applications as its
+ancient rival the four-cycle or Otto type, as demonstrated by Beau de
+Rocha in 1862.
+
+Thermodynamically, the methods of the two types are equal as far as
+combustion is concerned, and compression may favor in a small degree the
+four-cycle type as well as the purity of the charge. The cylinder volume
+of the two-cycle motor is much smaller per unit of power, and the
+enveloping cylinder surface is therefore greater per unit of volume.
+Hence more heat is carried off by the jacket water during compression,
+and the higher compression available from this tends to increase the
+economy during compression which is lost during expansion.
+
+From the above considerations it may be safely stated that a _lower_
+temperature and higher pressure of charge at the beginning of
+compression is obtained in the two-cycle motor, greater weight of charge
+and greater specific power of higher compression resulting in higher
+thermal efficiency. The smaller cylinder for the same power of the
+two-cycle motor gives less friction surface per impulse than of the
+other type; although the crank-chamber pressure may, in a measure,
+balance the friction of the four-cycle type. Probably the strongest
+points in favor of the two-cycle type are the lighter fly-wheel and the
+absence of valves and valve gear, making this type the most simple in
+construction and the lightest in weight for its developed power. Yet,
+for the larger power units, the four-cycle type will no doubt always
+maintain the standard for efficiency and durability of action.
+
+The distribution of the charge and its degree of mixture with the
+remains of the previous explosion in the clearance space, has been a
+matter of discussion for both types of explosive motors, with doubtful
+results. In Fig. 10, A we illustrate what theory suggests as to the
+distribution of the fresh charge in a two-cycle motor, and in Fig. 10, B
+what is the probable distribution of the mixture when the piston starts
+on its compressive stroke. The arrows show the probable direction of
+flow of the fresh charge and burnt gases at the crucial moment.
+
+[Illustration: Fig. 10.--Diagrams Contrasting Action of Two- and
+Four-Cycle Cylinders on Exhaust and Intake Stroke.]
+
+In Fig. 10, C is shown the complete out-sweep of the products of
+combustion for the full extent of the piston stroke of a four-cycle
+motor, leaving only the volume of the clearance to mix with the new
+charge and at D the manner by which the new charge sweeps by the
+ignition device, keeping it cool and avoiding possibilities of
+pre-ignition by undue heating of the terminals of the sparking device.
+Thus, by enveloping the sparking device with the pure mixture, ignition
+spreads through the charge with its greatest possible velocity, a most
+desirable condition in high-speed motors with side-valve chambers and
+igniters within the valve chamber.
+
+
+THEORY OF THE GAS AND GASOLINE ENGINE
+
+The laws controlling the elements that create a power by their expansion
+by heat due to combustion, when properly understood, become a matter of
+computation in regard to their value as an agent for generating power in
+the various kinds of explosive engines. The method of heating the
+elements of power in explosive engines greatly widens the limits of
+temperature as available in other types of heat-engines. It disposes of
+many of the practical troubles of hot-air, and even of steam-engines, in
+the simplicity and directness of application of the elements of power.
+In the explosive engine the difficulty of conveying heat for producing
+expansive effect by convection is displaced by the generation of the
+required heat within the expansive element and at the instant of its
+useful work. The low conductivity of heat to and from air has been the
+great obstacle in the practical development of the hot-air engine;
+while, on the contrary, it has become the source of economy and
+practicability in the development of the internal-combustion engine.
+
+The action of air, gas, and the vapors of gasoline and petroleum oil,
+whether singly or mixed, is affected by changes of temperature
+practically in nearly the same ratio; but when the elements that produce
+combustion are interchanged in confined spaces, there is a marked
+difference of effect. The oxygen of the air, the hydrogen and carbon of
+a gas, or vapor of gasoline or petroleum oil are the elements that by
+combustion produce heat to expand the nitrogen of the air and the watery
+vapor produced by the union of the oxygen in the air and the hydrogen in
+the gas, as well as also the monoxide and carbonic-acid gas that may be
+formed by the union of the carbon of gas or vapor with part of the
+oxygen of the air. The various mixtures as between air and gas, or air
+and vapor, with the proportion of the products of combustion left in the
+cylinder from a previous combustion, form the elements to be considered
+in estimating the amount of pressure that may be obtained by their
+combustion and expansive force.
+
+
+EARLY GAS ENGINE FORMS
+
+The working process of the explosive motor may be divided into three
+principal types: 1. Motors with charges igniting at constant volume
+without compression, such as the Lenoir, Hugon, and other similar types
+now abandoned as wasteful in fuel and effect. 2. Motors with charges
+igniting at constant pressure with compression, in which a receiver is
+charged by a pump and the gases burned while being admitted to the motor
+cylinder, such as types of the Simon and Brayton engine. 3. Motors with
+charges igniting at constant volume with variable compression, such as
+the later two- and four-cycle motors with compression of the indrawn
+charge; limited in the two-cycle type and variable in the four-cycle
+type with the ratios of the clearance space in the cylinder. This
+principle produces the explosive motor of greatest efficiency.
+
+The phenomena of the brilliant light and its accompanying heat at the
+moment of explosion have been witnessed in the experiments of Dugald
+Clerk in England, the illumination lasting throughout the stroke; but in
+regard to time in a four-cycle engine, the incandescent state exists
+only one-quarter of the running time. Thus the time interval, together
+with the non-conductibility of the gases, makes the phenomena of a
+high-temperature combustion within the comparatively cool walls of a
+cylinder a practical possibility.
+
+
+THE ISOTHERMAL LAW
+
+The natural laws, long since promulgated by Boyle, Gay Lussac, and
+others, on the subject of the expansion and compression of gases by
+force and by heat, and their variable pressures and temperatures when
+confined, are conceded to be practically true and applicable to all
+gases, whether single, mixed, or combined.
+
+The law formulated by Boyle only relates to the compression and
+expansion of gases without a change of temperature, and is stated in
+these words:
+
+_If the temperature of a gas be kept constant, its pressure or elastic
+force will vary inversely as the volume it occupies._
+
+It is expressed in the formula P × V = C, or pressure × volume =
+constant. Hence, C/P = V and C/V = P.
+
+Thus the curve formed by increments of pressure during the expansion or
+compression of a given volume of gas without change of temperature is
+designated as the isothermal curve in which the volume multiplied by the
+pressure is a constant value in expansion, and inversely the pressure
+divided by the volume is a constant value in compressing a gas.
+
+But as compression and expansion of gases require force for their
+accomplishment mechanically, or by the application or abstraction of
+heat chemically, or by convection, a second condition becomes involved,
+which was formulated into a law of thermodynamics by Gay Lussac under
+the following conditions: A given volume of gas under a free piston
+expands by heat and contracts by the loss of heat, its volume causing a
+proportional movement of a free piston equal to 1/273 part of the
+cylinder volume for each degree Centigrade difference in temperature, or
+1/492 part of its volume for each degree Fahrenheit. With a fixed piston
+(constant volume), the pressure is increased or decreased by an increase
+or decrease of heat in the same proportion of 1/273 part of its pressure
+for each degree Centigrade, or 1/492 part of its pressure for each
+degree Fahrenheit change in temperature. This is the natural sequence of
+the law of mechanical equivalent, which is a necessary deduction from
+the principle that nothing in nature can be lost or wasted, for all the
+heat that is imparted to or abstracted from a gaseous body must be
+accounted for, either as heat or its equivalent transformed into some
+other form of energy. In the case of a piston moving in a cylinder by
+the expansive force of heat in a gaseous body, all the heat expended in
+expansion of the gas is turned into work; the balance must be accounted
+for in absorption by the cylinder or radiation.
+
+
+THE ADIABATIC LAW
+
+This theory is equally applicable to the cooling of gases by abstraction
+of heat or by cooling due to expansion by the motion of a piston. The
+denominators of these heat fractions of expansion or contraction
+represent the absolute zero of cold below the freezing-point of water,
+and read -273° C. or -492.66° = -460.66° F. below zero; and these are
+the starting-points of reference in computing the heat expansion in
+gas-engines. According to Boyle's law, called the first law of gases,
+there are but two characteristics of a gas and their variations to be
+considered, _viz_., volume and pressure: while by the law of Gay Lussac,
+called the second law of gases, a third is added, consisting of the
+value of the absolute temperature, counting from absolute zero to the
+temperatures at which the operations take place. This is the _Adiabatic_
+law.
+
+The ratio of the variation of the three conditions--volume, pressure,
+and heat--from the absolute zero temperature has a certain rate, in
+which the volume multiplied by the pressure and the product divided by
+the absolute temperature equals the ratio of expansion for each degree.
+If a volume of air is contained in a cylinder having a piston and fitted
+with an indicator, the piston, if moved to and fro slowly, will
+alternately compress and expand the air, and the indicator pencil will
+trace a line or lines upon the card, which lines register the change of
+pressure and volume occurring in the cylinder. If the piston is
+perfectly free from leakage, and it be supposed that the temperature of
+the air is kept quite constant, then the line so traced is called an
+_Isothermal line_, and the pressure at any point when multiplied by the
+volume is a constant, according to Boyle's law,
+
+  _pv_ = a constant.
+
+If, however, the piston is moved very rapidly, the air will not remain
+at constant temperature, but the temperature will increase because work
+has been done upon the air, and the heat has no time to escape by
+conduction. If no heat whatever is lost by any cause, the line will be
+traced over and over again by the indicator pencil, the cooling by
+expansion doing work precisely equalling the heating by compression.
+This is the line of no transmission of heat, therefore known as
+_Adiabatic_.
+
+[Illustration: Fig. 11.--Diagram Isothermal and Adiabatic Lines.]
+
+The expansion of a gas 1/273 of its volume for every degree Centigrade,
+added to its temperature, is equal to the decimal .00366, the
+coefficient of expansion for Centigrade units. To any given volume of a
+gas, its expansion may be computed by multiplying the coefficient by
+the number of degrees, and by reversing the process the degree of
+acquired heat may be obtained approximately. These methods are not
+strictly in conformity with the absolute mathematical formula, because
+there is a small increase in the increment of expansion of a dry gas,
+and there is also a slight difference in the increment of expansion due
+to moisture in the atmosphere and to the vapor of water formed by the
+union of the hydrogen and oxygen in the combustion chamber of explosive
+engines.
+
+
+TEMPERATURE COMPUTATIONS
+
+The ratio of expansion on the Fahrenheit scale is derived from the
+absolute temperature below the freezing-point of water (32°) to
+correspond with the Centigrade scale; therefore 1/492.66 = .0020297, the
+ratio of expansion from 32° for each degree rise in temperature on the
+Fahrenheit scale. As an example, if the temperature of any volume of air
+or gas at constant volume is raised, say from 60° to 2000° F., the
+increase in temperature will be 1940°. The ratio will be 1/520.66 =
+.0019206. Then by the formula:
+
+Ratio × acquired temp. × initial pressure = the gauge pressure; and
+.0019206 × 1940° × 14.7 = 54.77 lbs.
+
+By another formula, a convenient ratio is obtained by (absolute
+pressure)/(absolute temp.) or 14.7/520.66 = .028233; then, using the
+difference of temperature as before, .028233 × 1940° = 54.77 lbs.
+pressure.
+
+By another formula, leaving out a small increment due to specific heat
+at high temperatures:
+
+      Atmospheric pressure × absolute temp. + acquired temp.
+  I. -------------------------------------------------------- =
+                 Absolute temp. + initial temp.
+
+absolute pressure due to the acquired temperature, from which the
+atmospheric pressure is deducted for the gauge pressure. Using the
+foregoing example, we have (14.7 × 460.66° + 2000°)/(460.66 + 60°) =
+69.47 - 14.7 = 54.77, the gauge pressure, 460.66 being the absolute
+temperature for zero Fahrenheit.
+
+For obtaining the volume of expansion of a gas from a given increment of
+heat, we have the approximate formula:
+
+       Volume × absolute temp. + acquired temp.
+  II. ------------------------------------------ =
+            Absolute temp. + initial temp.
+
+heated volume. In applying this formula to the foregoing example, the
+figures become:
+
+        460.66° + 2000°
+  I. × ----------------- = 4.72604 volumes.
+         460.66 + 60°
+
+From this last term the gauge pressure may be obtained as follows:
+
+III. 4.72604 × 14.7 = 69.47 lbs. absolute - 14.7 lbs. atmospheric
+pressure = 54.77 lbs. gauge pressure; which is the theoretical pressure
+due to heating air in a confined space, or at constant volume from 60°
+to 2000° F.
+
+By inversion of the heat formula for absolute pressure we have the
+formula for the acquired heat, derived from combustion at constant
+volume from atmospheric pressure to gauge pressure plus atmospheric
+pressure as derived from Example I., by which the expression
+
+   absolute pressure × absolute temp. + initial temp.
+  ----------------------------------------------------
+               initial absolute pressure
+
+= absolute temperature + temperature of combustion, from which the
+acquired temperature is obtained by subtracting the absolute
+temperature.
+
+Then, for example, (69.47 × 460.66 + 60)/14.7 = 2460.66, and 2460.66 -
+460.66 = 2000°, the theoretical heat of combustion. The dropping of
+terminal decimals makes a small decimal difference in the result in the
+different formulas.
+
+
+HEAT AND ITS WORK
+
+By Joule's law of the mechanical equivalent of heat, whenever heat is
+imparted to an elastic body, as air or gas, energy is generated and
+mechanical work produced by the expansion of the air or gas. When the
+heat is imparted by combustion within a cylinder containing a movable
+piston, the mechanical work becomes an amount measurable by the observed
+pressure and movement of the piston. The heat generated by the explosive
+elements and the expansion of the non-combining elements of nitrogen and
+water vapor that may have been injected into the cylinder as moisture in
+the air, and the water vapor formed by the union of the oxygen of the
+air with the hydrogen of the gas, all add to the energy of the work from
+their expansion by the heat of internal combustion. As against this, the
+absorption of heat by the walls of the cylinder, the piston, and
+cylinder-head or clearance walls, becomes a modifying condition in the
+force imparted to the moving piston.
+
+It is found that when any explosive mixture of air and gas or
+hydrocarbon vapor is fired, the pressure falls far short of the pressure
+computed from the theoretical effect of the heat produced, and from
+gauging the expansion of the contents of a cylinder. It is now well
+known that in practice the high efficiency which is promised by
+theoretical calculation is never realized; but it must always be
+remembered that the heat of combustion is the real agent, and that the
+gases and vapors are but the medium for the conversion of inert elements
+of power into the activity of energy by their chemical union. The theory
+of combustion has been the leading stimulus to large expectations with
+inventors and constructors of explosive motors; its entanglement with
+the modifying elements in practice has delayed the best development in
+construction, and as yet no really positive design of best form or
+action seems to have been accomplished, although great progress has been
+made during the past decade in the development of speed, reliability,
+economy, and power output of the individual units of this comparatively
+new power.
+
+One of the most serious difficulties in the practical development of
+pressure, due to the theoretical computations of the pressure value of
+the full heat, is probably caused by imparting the heat of the fresh
+charge to the balance of the previous charge that has been cooled by
+expansion from the maximum pressure to near the atmospheric pressure of
+the exhaust. The retardation in the velocity of combustion of perfectly
+mixed elements is now well known from experimental trials with measured
+quantities; but the principal difficulty in applying these conditions to
+the practical work of an explosive engine where a necessity for a large
+clearance space cannot be obviated, is in the inability to obtain a
+maximum effect from the imperfect mixture and the mingling of the
+products of the last explosion with the new mixture, which produces a
+clouded condition that makes the ignition of the mass irregular or
+chattering, as observed in the expansion lines of indicator cards; but
+this must not be confounded with the reaction of the spring in the
+indicator.
+
+Stratification of the mixture has been claimed as taking place in the
+clearance chamber of the cylinder; but this is not a satisfactory
+explanation in view of the vortical effect of the violent injection of
+the air and gas or vapor mixture. It certainly cannot become a perfect
+mixture in the time of a stroke of a high-speed motor of the two-cycle
+class. In a four-cycle engine, making 1,500 revolutions per minute, the
+injection and compression in any one cylinder take place in one
+twenty-fifth of a second--formerly considered far too short a time for a
+perfect infusion of the elements of combustion but now very easily taken
+care of despite the extremely high speed of numerous aviation and
+automobile power-plants.
+
+TABLE I.--EXPLOSION AT CONSTANT VOLUME IN A CLOSED CHAMBER.
+
+  =====+================================+======+=======+========+======
+  Dia- |                                | Temp.| Time  |  Ob-   | Com-
+  gram |                                |  of  |  of   | served |puted
+  Curve|        Mixture Injected.       |Injec-|Explo- | Gauge  |Temp.
+  Fig. |                                | tion | sion  |Pressure|Fahr.
+   8.  |                                | Fahr.|Second.| Pounds |
+  -----+--------------------------------+------+-------+--------+------
+  _a_  |1 volume gas to 14 volumes air. |  64° | 0.45  |  40.   |1,483°
+  _b_  |1   "     "  "  13    "     "   |  51° | 0.31  |  51.5  |1,859°
+  _c_  |1   "     "  "  12    "     "   |  51° | 0.24  |  60.   |2,195°
+  _d_  |1   "     "  "  11    "     "   |  51° | 0.17  |  61.   |2,228°
+  _e_  |1   "     "  "   9    "     "   |  62° | 0.08  |  78.   |2,835°
+  _f_  |1   "     "  "   7    "     "   |  62° | 0.06  |  87.   |3,151°
+  _g_  |1   "     "  "   6    "     "   |  51° | 0.04  |  90.   |3,257°
+  _h_  |1   "     "  "   5    "     "   |  51° | 0.055 |  91.   |3,293°
+  _i_  |1   "     "  "   4    "     "   |  66° | 0.16  |  80.   |2,871°
+  -----+--------------------------------+------+-------+--------+------
+
+In an examination of the times of explosion and the corresponding
+pressures in both tables, it will be seen that a mixture of 1 part gas
+to 6 parts air is the most effective and will give the highest mean
+pressure in a gas-engine. There is a limit to the relative proportions
+of illuminating gas and air mixture that is explosive, somewhat
+variable, depending upon the proportion of hydrogen in the gas. With
+ordinary coal-gas, 1 of gas to 15 parts of air; and on the lower end of
+the scale, 1 volume of gas to 2 parts air, are non-explosive. With
+gasoline vapor the explosive effect ceases at 1 to 16, and a saturated
+mixture of equal volumes of vapor and air will not explode, while the
+most intense explosive effect is from a mixture of 1 part vapor to 9
+parts air. In the use of gasoline and air mixtures from a carburetor,
+the best effect is from 1 part saturated air to 8 parts free air.
+
+TABLE II.--PROPERTIES AND EXPLOSIVE TEMPERATURE OF A MIXTURE OF ONE PART
+OF ILLUMINATING GAS OF 660 THERMAL UNITS PER CUBIC FOOT WITH VARIOUS
+PROPORTIONS OF AIR WITHOUT MIXTURE OF CHARGE WITH THE PRODUCTS OF A
+PREVIOUS EXPLOSION.
+
+  [A] Proportion, Air to Gas by Volumes.
+  [B] Pounds in One Cubic Foot of Mixture.
+  [C] Specific Heat. Heat Units Required to Raise 1 Lb. 1 Deg.
+      Fahrenheit. Constant Pressure.
+  [D] Specific Heat. Heat Units Required to Raise 1 Lb. 1 Deg.
+      Fahrenheit. Constant Volume.
+  [E] Heat to Raise One Cubic Foot of Mixture 1 Deg. Fahr.
+  [F] Heat Units Evolved by Combustion.
+  [G] Ratio Col. 6/5
+  [H] Usual Combustion Efficiency.
+  [I] Usual Rise of Temperature due to Explosion at Constant Volume.
+
+  =======+========+======+======+========+======+=======+=====+=====
+    [A]  |   [B]  |  [C] |  [D] |   [E]  |  [F] |  [G]  | [H] | [I]
+  -------+--------+------+------+--------+------+-------+-----+-----
+   6 to 1| .074195| .2668| .1913| .014189| 94.28| 6644.6| .465| 3090
+   7 to 1| .075012| .2628| .1882| .014116| 82.  | 5844.4| .518| 3027
+   8 to 1| .075647| .2598| .1858| .014059| 73.33| 5216.1| .543| 2832
+   9 to 1| .076155| .2575| .1846| .014013| 66.  | 4709.9| .56 | 2637
+  10 to 1| .076571| .2555| .1825| .013976| 60.  | 4293. | .575| 2468
+  11 to 1| .076917| .2540| .1813| .013945| 55.  | 3944. | .585| 2307
+  12 to 1| .077211| .2526| .1803| .013922| 50.77| 3646.7| .58 | 2115
+  -------+--------+------+------+--------+------+-------+-----+-----
+
+The weight of a cubic foot of gas and air mixture as given in Col. 2 is
+found by adding the number of volumes of air multiplied by its weight,
+.0807, to one volume of gas of weight .035 pound per cubic foot and
+dividing by the total number of volumes; for example, as in the table, 6
+× .0807 = .5192/7 = .074195 as in the first line, and so on for any
+mixture or for other gases of different specific weight per cubic foot.
+The heat units evolved by combustion of the mixture (Col. 6) are
+obtained by dividing the total heat units in a cubic foot of gas by the
+total proportion of the mixture, 660/7 = 94.28 as in the first line of
+the table. Col. 5 is obtained by multiplying the weight of a cubic foot
+of the mixture in Col. 2 by the specific heat at a constant volume (Col.
+4), Col. 6/Col. 5 = Col. 7 the total heat ratio, of which Col. 8 gives
+the usual combustion efficiency--Col. 7 × Col. 8 gives the absolute rise
+in temperature of a pure mixture, as given in Col. 9.
+
+The many recorded experiments made to solve the discrepancy between the
+theoretical and the actual heat development and resulting pressures in
+the cylinder of an explosive motor, to which much discussion has been
+given as to the possibilities of dissociation and the increased specific
+heat of the elements of combustion and non-combustion, as well, also, of
+absorption and radiation of heat, have as yet furnished no satisfactory
+conclusion as to what really takes place within the cylinder walls.
+There seems to be very little known about dissociation, and somewhat
+vague theories have been advanced to explain the phenomenon. The fact
+is, nevertheless, apparent as shown in the production of water and other
+producer gases by the use of steam in contact with highly incandescent
+fuel. It is known that a maximum explosive mixture of pure gases, as
+hydrogen and oxygen or carbonic oxide and oxygen, suffers a contraction
+of one-third their volume by combustion to their compounds, steam or
+carbonic acid. In the explosive mixtures in the cylinder of a motor,
+however, the combining elements form so small a proportion of the
+contents of the cylinder that the shrinkage of their volume amounts to
+no more than 3 per cent. of the cylinder volume. This by no means
+accounts for the great heat and pressure differences between the
+theoretical and actual effects.
+
+
+CONVERSION OF HEAT TO POWER
+
+The utilization of heat in any heat-engine has long been a theme of
+inquiry and experiment with scientists and engineers, for the purpose of
+obtaining the best practical conditions and construction of heat-engines
+that would represent the highest efficiency or the nearest approach to
+the theoretical value of heat, as measured by empirical laws that have
+been derived from experimental researches relating to its ultimate
+volume. It is well known that the steam-engine returns only from 12 to
+18 per cent. of the power due to the heat generated by the fuel, about
+25 per cent. of the total heat being lost in the chimney, the only use
+of which is to create a draught for the fire; the balance, some 60 per
+cent., is lost in the exhaust and by radiation. The problem of utmost
+utilization of force in steam has nearly reached its limit.
+
+The internal-combustion system of creating power is comparatively new in
+practice, and is but just settling into definite shape by repeated
+trials and modification of details, so as to give somewhat reliable data
+as to what may be expected from the rival of the steam-engine as a prime
+mover. For small powers, the gas, gasoline, and petroleum-oil engines
+are forging ahead at a rapid rate, filling the thousand wants of
+manufacture and business for a power that does not require expensive
+care, that is perfectly safe at all times, that can be used in any place
+in the wide world to which its concentrated fuel can be conveyed, and
+that has eliminated the constant handling of crude fuel and water.
+
+
+REQUISITES FOR BEST POWER EFFECT
+
+The utilization of heat in a gas-engine is mainly due to the manner in
+which the products entering into combustion are distributed in relation
+to the movement of the piston. The investigation of the foremost
+exponent of the theory of the explosive motor was prophetic in
+consideration of the later realization of the best conditions under
+which these motors can be made to meet the requirements of economy and
+practicability. As early as 1862, Beau de Rocha announced, in regard to
+the coming power, that four requisites were the basis of operation for
+economy and best effect. 1. The greatest possible cylinder volume with
+the least possible cooling surface. 2. The greatest possible rapidity of
+expansion. Hence, _high speed_. 3. The greatest possible expansion.
+_Long stroke._ 4. The greatest possible pressure at the commencement of
+expansion. _High compression._
+
+
+
+
+CHAPTER III
+
+    Efficiency of Internal Combustion Engines--Various Measures of
+    Efficiency--Temperatures and Pressures--Factors Governing
+    Economy--Losses in Wall Cooling--Value of Indicator Cards--
+    Compression in Explosive Motors--Factors Limiting Compression--
+    Causes of Heat Losses and Inefficiency--Heat Losses to Cooling
+    Water.
+
+
+EFFICIENCY OF INTERNAL COMBUSTION ENGINES
+
+Efficiencies are worked out through intricate formulas for a variety of
+theoretical and unknown conditions of combustion in the cylinder: ratios
+of clearance and cylinder volume, and the uncertain condition of the
+products of combustion left from the last impulse and the wall
+temperature. But they are of but little value, except as a mathematical
+inquiry as to possibilities. The real commercial efficiency of a gas or
+gasoline-engine depends upon the volume of gas or liquid at some
+assigned cost, required per actual brake horse-power per hour, in which
+an indicator card should show that the mechanical action of the valve
+gear and ignition was as perfect as practicable, and that the ratio of
+clearance, space, and cylinder volume gave a satisfactory terminal
+pressure and compression: _i.e._, the difference between the power
+figured from the indicator card and the brake power being the friction
+loss of the engine.
+
+In four-cycle motors of the compression type, the efficiencies are
+greatly advanced by compression, producing a more complete infusion of
+the mixture of gas or vapor and air, quicker firing, and far greater
+pressure than is possible with the two-cycle type previously described.
+In the practical operation of the gas-engine during the past twenty
+years, the gas-consumption efficiencies per indicated horse-power have
+gradually risen from 17 per cent. to a maximum of 40 per cent. of the
+theoretical heat, and this has been done chiefly through a decreased
+combustion chamber and increased compression--the compression having
+gradually increased in practice from 30 lbs. per square inch to above
+100; but there seems to be a limit to compression, as the efficiency
+ratio decreases with greater increase in compression. It has been shown
+that an ideal efficiency of 33 per cent. for 38 lbs., compression will
+increase to 40 per cent. for 66 lbs., and 43 per cent. for 88 lbs.
+compression. On the other hand, greater compression means greater
+explosive pressure and greater strain on the engine structure, which
+will probably retain in future practice the compression between the
+limits of 40 and 90 lbs. except in super-compression engines intended
+for high altitude work where compression pressures as high as 125 pounds
+have been used.
+
+In experiments made by Dugald Clerk, in England, with a combustion
+chamber equal to 0.6 of the space swept by the piston, with a
+compression of 38 lbs., the consumption of gas was 24 cubic feet per
+indicated horse-power per hour. With 0.4 compression space and 61 lbs.
+compression, the consumption of gas was 20 cubic feet per indicated
+horse-power per hour; and with 0.34 compression space and 87 lbs.
+compression, the consumption of gas fell to 14.8 cubic feet per
+indicated horse-power per hour--the actual efficiencies being
+respectively 17, 21, and 25 per cent. This was with a Crossley
+four-cycle engine.
+
+
+VARIOUS MEASURES OF EFFICIENCY
+
+The efficiencies in regard to power in a heat-engine may be divided
+into four kinds, as follows: I. The first is known as the _maximum
+theoretical efficiency_ of a perfect engine (represented by the
+lines in the indicator diagram). It is expressed by the formula
+(T_{1} - T_{0})/T_{1} and shows the work of a perfect cycle in an engine
+working between the received temperature + absolute temperature (T_{1})
+and the initial atmospheric temperature + absolute temperature (T_{0}).
+II. The second is the _actual heat efficiency_, or the ratio of the heat
+turned into work to the total heat received by the engine. It expresses
+the _indicated horse-power_. III. The third is the ratio between the
+second or _actual heat efficiency_ and the first or _maximum theoretical
+efficiency_ of a perfect cycle. It represents the greatest possible
+utilization of the power of heat in an internal-combustion engine. IV.
+The fourth is the _mechanical efficiency_. This is the ratio between the
+actual horse-power delivered by the engine through a dynamometer or
+measured by a brake (brake horse-power), and the indicated horse-power.
+The difference between the two is the power lost by engine friction. In
+regard to the general heat efficiency of the materials of power in
+explosive engines, we find that with good illuminating gas the practical
+efficiency varies from 25 to 40 per cent.; kerosene-motors, 20 to 30;
+gasoline-motors, 20 to 32; acetylene, 25 to 35; alcohol, 20 to 30 per
+cent. of their heat value. The great variation is no doubt due to
+imperfect mixtures and variable conditions of the old and new charge in
+the cylinder; uncertainty as to leakage and the perfection of
+combustion. In the Diesel motors operating under high pressure, up to
+nearly 500 pounds, an efficiency of 36 per cent. is claimed.
+
+[Illustration: Fig. 12.--Graphic Diagram Showing Approximate Utilization
+of Fuel Burned in Internal-Combustion Engine.]
+
+The graphic diagram at Fig. 12 is of special value as it shows clearly
+how the heat produced by charge combustion is expended in an engine of
+average design.
+
+On general principles the greater difference between the heat of
+combustion and the heat at exhaust is the relative measure of the heat
+turned into work, which represents the degree of efficiency without loss
+during expansion. The mathematical formulas appertaining to the
+computation of the element of heat and its work in an explosive engine
+are in a large measure dependent upon assumed values, as the conditions
+of the heat of combustion are made uncertain by the mixing of the fresh
+charge with the products of a previous combustion, and by absorption,
+radiation, and leakage. The computation of the temperature from the
+observed pressure may be made as before explained, but for
+compression-engines the needed starting-points for computation are very
+uncertain, and can only be approximated from the exact measure and value
+of the elements of combustion in a cylinder charge.
+
+
+TEMPERATURES AND PRESSURES
+
+Owing to the decrease from atmospheric pressure in the indrawing charge
+of the cylinder, caused by valve and frictional obstruction, the
+compression seldom starts above 13 lbs. absolute, especially in
+high-speed engines. Col. 3 in the following table represents the
+approximate absolute compression pressure for the clearance percentage
+and ratio in Cols. 1 and 2, while Col. 4 indicates the gauge pressure
+from the atmospheric line. The temperatures in Col. 5 are due to the
+compression in Col. 3 from an assumed temperature of 560° F. in the
+mixture of the fresh charge of 6 air to 1 gas with the products of
+combustion left in the clearance chamber from the exhaust stroke of a
+medium-speed motor. This temperature is subject to considerable
+variation from the difference in the heat-unit power of the gases and
+vapors used for explosive power, as also of the cylinder-cooling effect.
+In Col. 6 is given the approximate temperatures of explosion for a
+mixture of air 6 to gas 1 of 660 heat units per cubic foot, for the
+relative values of the clearance ratio in Col. 2 at constant volume.
+
+TABLE III.--GAS-ENGINE CLEARANCE RATIOS, APPROXIMATE COMPRESSION,
+TEMPERATURES OF EXPLOSION AND EXPLOSIVE PRESSURES WITH A MIXTURE OF GAS
+OF 660 HEAT UNITS PER CUBIC FOOT AND MIXTURE OF GAS 1 TO 6 OF AIR.
+
+  [A] Clearance Per Cent. of Piston Volume.
+  [B] Ratio (_V_/_V_{c}_) = (_P_ + _C_ Vol.)/Clearance
+  [C] Approximate Compression from 13 Pounds Absolute.
+  [D] Approximate Gauge Pressure.
+  [E] Absolute Temperature of Compression from 560 Deg. Fahrenheit in
+      Cylinder.
+  [F] Absolute Temperature of Explosion. Gas, 1 part; Air, 6 parts.
+  [G] Approximate Explosion Pressure Absolute.
+  [H] Approximate Gauge Pressure.
+  [I] Approximate Temperature of Explosion, Fahrenheit.
+
+  =====+======+======+=====+======+======+=====+=====+=====
+   [A] | [B]  | [C]  | [D] | [E]  | [F]  | [G] | [H] | [I]
+  -----+------+------+-----+------+------+-----+-----+-----
+    1  |  2   |  3   |  4  |  5   |  6   |  7  |  8  |  9
+  -----+------+------+-----+------+------+-----+-----+-----
+       |      | Lbs. |     | Deg. | Deg. |Lbs. |Lbs. | Deg.
+  .50  | 3.   |  57. | 42. | 822. | 2488 | 169 | 144 | 2027
+  .444 | 3.25 |  65. | 50. | 846. | 2568 | 197 | 182 | 2107
+  .40  | 3.50 |  70. | 55. | 868. | 2638 | 212 | 197 | 2177
+  .363 | 3.75 |  77. | 62. | 889. | 2701 | 234 | 219 | 2240
+  .333 | 4.   |  84. | 69. | 910. | 2751 | 254 | 239 | 2290
+  .285 | 4.50 | 102. | 88. | 955. | 2842 | 303 | 288 | 2381
+  .25  | 5.   | 114. | 99. | 983. | 2901 | 336 | 321 | 2440
+  -----+------+------+-----+------+------+-----+-----+-----
+
+
+FACTORS GOVERNING ECONOMY
+
+In view of the experiments in this direction, it clearly shows that in
+practical work, to obtain the greatest economy per effective brake
+horse-power, it is necessary: 1st. To transform the heat into work with
+the greatest rapidity mechanically allowable. This means high piston
+speed. 2d. To have high initial compression. 3d. To reduce the duration
+of contact between the hot gases and the cylinder walls to the smallest
+amount possible; which means short stroke and quick speed, with a
+spherical cylinder head. 4th. To adjust the temperature of the jacket
+water to obtain the most economical output of actual power. This means
+water-tanks or water-coils, with air-cooling surfaces suitable and
+adjustable to the most economical requirement of the engine, which by
+late trials requires the jacket water to be discharged at about 200° F.
+5th. To reduce the wall surface of the clearance space or combustion
+chamber to the smallest possible area, in proportion to its required
+volume. This lessens the loss of the heat of combustion by exposure to a
+large surface, and allows of a higher mean wall temperature to
+facilitate the heat of compression.
+
+
+LOSSES IN WALL COOLING
+
+In an experimental investigation of the efficiency of a gas-engine under
+variable piston speeds made in France, it was found that the useful
+effect increases with the velocity of the piston--that is, with the rate
+of expansion of the burning gases with mixtures of uniform volumes: so
+that the variations of time of complete combustion at constant pressure,
+and the variations due to speed, in a way compensate in their
+efficiencies. The dilute mixture, being slow burning, will have its time
+and pressure quickened by increasing the speed.
+
+Careful trials give unmistakable evidence that the useful effect
+increases with the velocity of the piston--that is, with the rate of
+expansion of the burning gases. The time necessary for the explosion to
+become complete and to attain its maximum pressure depends not only on
+the composition of the mixture, but also upon the rate of expansion.
+This has been verified in experiments with a high-speed motor, at speeds
+from 500 to 2,000 revolutions per minute, or piston speeds of from 16 to
+64 feet per second. The increased speed of combustion due to increased
+piston speed is a matter of great importance to builders of gas-engines,
+as well as to the users, as indicating the mechanical direction of
+improvements to lessen the wearing strain due to high speed and to
+lighten the vibrating parts with increased strength, in order that the
+balancing of high-speed engines may be accomplished with the least
+weight.
+
+From many experiments made in Europe and in the United States, it has
+been conclusively proved that excessive cylinder cooling by the
+water-jacket results in a marked loss of efficiency. In a series of
+experiments with a simplex engine in France, it was found that a saving
+of 7 per cent. in gas consumption per brake horse-power was made by
+raising the temperature of the jacket water from 141° to 165° F. A still
+greater saving was made in a trial with an Otto engine by raising the
+temperature of the jacket water from 61° to 140° F.--it being 9.5 per
+cent. less gas per brake horse-power.
+
+It has been stated that volumes of similar cylinders increase as the
+cube of their diameters, while the surface of their cold walls varies as
+the square of their diameters; so that for large cylinders the ratio of
+surface to volume is less than for small ones. This points to greater
+economy in the larger engines. The study of many experiments goes to
+prove that combustion takes place gradually in the gas-engine cylinder,
+and that the rate of increase of pressure or rapidity of firing is
+controlled by dilution and compression of the mixture, as well as by the
+rate of expansion or piston speed. The rate of combustion also depends
+on the size and shape of the explosion chamber, and is increased by the
+mechanical agitation of the mixture during combustion, and still more by
+the mode of firing.
+
+
+VALUE OF INDICATOR CARDS
+
+[Illustration: Fig. 13.--Otto Four-Cycle Card.]
+
+To the uninitiated, indicator cards are considerable of a mystery; to
+those capable of reading them they form an index relative to the action
+of any engine. An indicator card, such as shown at Fig. 13, is merely a
+graphical representation of the various pressures existing in the
+cylinder for different positions of the piston. The length is to some
+scale that represents the stroke of the piston. During the intake
+stroke, the pressure falls below the atmospheric line. During
+compression, the curve gradually becomes higher owing to increasing
+pressure as the volume is reduced. After ignition the pressure line
+moves upward almost straight, then as the piston goes down on the
+explosion stroke, the pressure falls gradually to the point of exhaust
+valve, opening when the sudden release of the imprisoned gas causes a
+reduction in pressure to nearly atmospheric. An indicator card, or a
+series of them, will always show by its lines the normal or defective
+condition of the inlet valve and passages; the actual line of
+compression; the firing moment; the pressure of explosion; the velocity
+of combustion; the normal or defective line of expansion, as measured by
+the adiabatic curve, and the normal or defective operation of the
+exhaust valve, exhaust passages, and exhaust pipe. In fact, all the
+cycles of an explosive motor may be made a practical study from a close
+investigation of the lines of an indicator card.
+
+[Illustration: Fig. 14.--Diesel Motor Card.]
+
+A most unique card is that of the Diesel motor (Fig. 14), which involves
+a distinct principle in the design and operation of internal-combustion
+motors, in that instead of taking a mixed charge for instantaneous
+explosion, its charge primarily is of air and its compression to a
+pressure at which a temperature is attained above the igniting point of
+the fuel, then injecting the fuel under a still higher pressure by which
+spontaneous combustion takes place gradually with increasing volume over
+the compression for part of the stroke or until the fuel charge is
+consumed. The motor thus operating between the pressures of 500 and 35
+lbs. per square inch, with a clearance of about 7 per cent., has given
+an efficiency of 36 per cent. of the total heat value of kerosene oil.
+
+
+COMPRESSION IN EXPLOSIVE MOTORS
+
+That the compression in a gas, gasoline, or oil-engine has a direct
+relation to the power obtained, has been long known to experienced
+builders, having been suggested by M. Beau de Rocha, in 1862, and
+afterward brought into practical use in the four-cycle or Otto type
+about 1880. The degree of compression has had a growth from zero, in the
+early engines, to the highest available due to the varying ignition
+temperatures of the different gases and vapors used for explosive fuel,
+in order to avoid premature explosion from the heat of compression. Much
+of the increased power for equal-cylinder capacity is due to compression
+of the charge from the fact that the most powerful explosion of gases,
+or of any form of explosive material, takes place when the particles are
+in the closest contact or cohesion with one another, less energy in this
+form being consumed by the ingredients themselves to bring about their
+chemical combination, and consequently more energy is given out in
+useful or available work. This is best shown by the ignition of
+gunpowder, which, when ignited in the open air, burns rapidly, but
+without explosion, an explosion only taking place if the powder be
+confined or compressed into a small space.
+
+[Illustration: Fig. 15.--Diagram of Heat in the Gas Engine Cylinder.]
+
+In a gas or gasoline-motor with a small clearance or compression
+space--with high compression--the surface with which the burning
+gases come into contact is much smaller in comparison with the
+compression space in a low-compression motor. Another advantage of a
+high-compression motor is that on account of the smaller clearance
+of combustion space less cooling water is required than with a
+low-compression motor, as the temperature, and consequently the
+pressure, falls more rapidly. The loss of heat through the water-jacket
+is thus less in the case of a high-compression than in that of a
+low-compression motor. In the non-compression type of motor the best
+results were obtained with a charge of 16 to 18 parts of gas and 100
+parts of air, while in the compression type the best results are
+obtained with an explosive mixture of 7 to 10 parts of gas and 100 parts
+of air, thus showing that by the utilization of compression a weaker
+charge with a greater thermal efficiency is permissible.
+
+It has been found that the explosive pressure resulting from the
+ignition of the charge of gas or gasoline-vapor and air in the
+gas-engine cylinder is about 4-1/2 times the pressure prior to ignition.
+The difficulty about getting high compression is that if the pressure is
+too high the charge is likely to ignite prematurely, as compression
+always results in increased temperature. The cylinder may become too
+hot, a deposit of carbon, a projecting electrode or plug body in the
+cylinder may become incandescent and ignite the charge which has been
+excessively heated by the high compression and mixture of the hot gases
+of the previous explosion.
+
+
+FACTORS LIMITING COMPRESSION
+
+With gasoline-vapor and air the compression should not be raised above
+about 90 to 95 pounds to the square inch, many manufacturers not going
+above 65 or 70 pounds. For natural gas the compression pressure may
+easily be raised to from 85 to 100 pounds per square inch. For gases of
+low calorific value, such as blast-furnace or producer-gas, the
+compression may be increased to from 140 to 190 pounds. In fact the
+ability to raise the compression to a high point with these gases is one
+of the principal reasons for their successful adoption for gas-engine
+use. In kerosene injection engines the compression of 250 pounds per
+square inch has been used with marked economy. Many troubles in regard
+to loss of power and increase of fuel have occurred and will no doubt
+continue, owing to the wear of valves, piston, and cylinder, which
+produces a loss in compression and explosive pressure and a waste of
+fuel by leakage. Faulty adjustment of valve movement is also a cause of
+loss of power; which may be from tardy closing of the inlet-valve or a
+too early opening of the exhaust-valve.
+
+The explosive pressure varies to a considerable amount in proportion to
+the compression pressure by the difference in fuel value and the
+proportions of air mixtures, so that for good illuminating gas the
+explosive pressure may be from 2.5 to 4 times the compression pressure.
+For natural gas 3 to 4.5, for gasoline 3 to 5, for producer-gas 2 to 3,
+and for kerosene by injection 3 to 6.
+
+The compression temperatures, although well known and easily computed
+from a known normal temperature of the explosive mixture, are subject to
+the effect of the uncertain temperature of the gases of the previous
+explosion remaining in the cylinder, the temperature of its walls, and
+the relative volume of the charge, whether full or scant; which are
+terms too variable to make any computations reliable or available.
+
+For the theoretical compression temperatures from a known normal
+temperature, we append a table of the rise in temperature for the
+compression pressures in the following table:
+
+TABLE IV.--COMPRESSION TEMPERATURES FROM A NORMAL TEMPERATURE OF 60
+DEGREES FAHRENHEIT.
+
+  ===============================+==============================
+  100 lbs. gauge            484° | 60 lbs. gauge            373°
+   90 lbs. gauge            459° | 50 lbs. gauge            339°
+   80 lbs. gauge            433° | 40 lbs. gauge            301°
+   70 lbs. gauge            404° | 30 lbs. gauge            258°
+  -------------------------------+------------------------------
+
+
+CHART FOR DETERMINING COMPRESSION PRESSURES
+
+A very useful chart (Fig. 16) for determining compression pressures in
+gasoline-engine cylinders for various ratios of compression space to
+total cylinder volume is given by P. S. Tice, and described in the
+Chilton Automobile Directory by the originator as follows:
+
+[Illustration: Fig. 16.--Chart Showing Relation Between Compression
+Volume and Pressure.]
+
+It is many times desirable to have at hand a convenient means for at
+once determining with accuracy what the compression pressure will be in
+a gasoline-engine cylinder, the relationship between the volume of the
+compression space and the total cylinder volume or that swept by the
+piston being known. The curve at Fig. 16 is offered as such a means. It
+is based on empirical data gathered from upward of two dozen modern
+automobile engines and represents what may be taken to be the results as
+found in practice. It is usual for the designer to find compression
+pressure values, knowing the volumes from the equation
+
+  P_{2} = P_{1} (V_{1}/V_{2})^{1.4}                                  1
+
+which is for adiabatic compression of air. Equation (1) is right enough
+in general form but gives results which are entirely too high, as
+almost all designers know from experience. The trouble lies in the
+interchange of heat between the compressed gases and the cylinder walls,
+in the diminution of the exponent (1.4 in the above) due to the lesser
+ratio of specific heat of gasoline vapor and in the transfer of heat
+from the gases which are being compressed to whatever fuel may enter the
+cylinder in an unvaporized condition. Also, there is always some piston
+leakage, and, if the form of the equation (1) is to be retained, this
+also tends to lower the value of the exponent. From experience with many
+engines, it appears that compression reaches its highest value in the
+cylinder for but a short range of motor speeds, usually during the
+mid-range. Also, it appears that, at those speeds at which compression
+shows its highest values, the initial pressure at the start of the
+compression stroke is from .5 to .9 lb. below atmospheric. Taking this
+latter loss value, which shows more often than those of lesser value,
+the compression is seen to start from an initial pressure of 13.9 lbs.
+per sq. in. absolute.
+
+Also, experiment shows that if the exponent be given the value 1.26,
+instead of 1.4, the equation will embrace all heat losses in the
+compressed gas, and compensate for the changed ratio of specific heats
+for the mixture and also for all piston leakage, in the average engine
+with rings in good condition and tight. In the light of the foregoing,
+and in view of results obtained from its use, the above curve is
+offered--values of P_{2} being found from the equation
+
+  P_{2} = 13.8 (V_{1}/V_{2})^{1.26}
+
+In using this curve it must be remembered that pressures are absolute.
+Thus: suppose it is desired to know the volumetric relationships of the
+cylinder for a compression pressure of 75 lbs. gauge. Add atmospheric
+pressure to the desired gauge pressure 14.7 + 75 = 89.7 lbs. absolute.
+Locate this pressure on the scale of ordinates and follow horizontally
+across to the curve and then vertically downward to the scale of
+abscissas, where the ratio of the combustion chamber volume to the total
+cylinder volume is given, which latter is equal to the sum of the
+combustion chamber volume and that of the piston sweep. In the above
+case it is found that the combustion space for a compression pressure of
+75 lbs. gauge will be .225 of the total cylinder volume, or .225 ÷ .775
+= .2905 of the piston sweep volume. Conversely, knowing the volumetric
+ratios, compression pressure can be read directly by proceeding from the
+scale of abscissas vertically to the curve and thence horizontally to
+the scale of ordinates.
+
+
+CAUSES OF HEAT LOSS AND INEFFICIENCY IN EXPLOSIVE MOTORS
+
+The difference realized in the practical operation of an internal
+combustion heat engine from the computed effect derived from the values
+of the explosive elements is probably the most serious difficulty that
+engineers have encountered in their endeavors to arrive at a rational
+conclusion as to where the losses were located, and the ways and means
+of design that would eliminate the causes of loss and raise the
+efficiency step by step to a reasonable percentage of the total
+efficiency of a perfect cycle.
+
+An authority on the relative condition of the chemical elements under
+combustion in closed cylinders attributes the variation of temperature
+shown in the fall of the expansion curve, and the suppression or
+retarded evolution of heat, entirely to the cooling action of the
+cylinder walls, and to this nearly all the phenomena hitherto obscure in
+the cylinder of a gas-engine. Others attribute the great difference
+between the theoretical temperature of combustion and the actual
+temperature realized in the practical operation of the gas-engine, a
+loss of more than one-half of the total heat energy of the combustibles,
+partly to the dissociation of the elements of combustion at extremely
+high temperatures and their reassociation by expansion in the cylinder,
+to account for the supposed continued combustion and extra adiabatic
+curve of the expansion line on the indicator card.
+
+[Illustration: Fig. 17.--The Thompson Indicator, an Instrument for
+Determining Compressions and Explosion Pressure Values and Recording
+Them on Chart.]
+
+The loss of heat to the walls of the cylinder, piston, and clearance
+space, as regards the proportion of wall surface to the volume, has
+gradually brought this point to its smallest ratio in the concave
+piston-head and globular cylinder-head, with the smallest possible space
+in the inlet and exhaust passage. The wall surface of a cylindrical
+clearance space or combustion chamber of one-half its unit diameter in
+length is equal to 3.1416 square units, its volume but 0.3927 of a cubic
+unit; while the same wall surface in a spherical form has a volume of
+0.5236 of a cubic unit. It will be readily seen that the volume is
+increased 33-1/3 per cent. in a spherical over a cylindrical form for
+equal wall surfaces at the moment of explosion, when it is desirable
+that the greatest amount of heat is generated, and carrying with it the
+greatest possible pressure from which the expansion takes place by the
+movement of the piston.
+
+[Illustration: Fig. 18.--Spherical Combustion Chamber.]
+
+[Illustration: Fig. 19.--Enlarged Combustion Chamber.]
+
+The spherical form cannot continue during the stroke for mechanical
+reasons; therefore some proportion of piston stroke of cylinder volume
+must be found to correspond with a spherical form of the combustion
+chamber to produce the least loss of heat through the walls during the
+combustion and expansion part of the stroke. This idea is illustrated in
+Figs. 18 and 19, showing how the relative volumes of cylinder stroke and
+combustion chamber may be varied to suit the requirements due to the
+quality of the elements of combustion.
+
+Although the concave piston-head shows economy in regard to the relation
+of the clearance volume to the wall area at the moment of explosive
+combustion, it may be clearly seen that its concavity increases its
+surface area and its capacity for absorbing heat, for which there is no
+provision for cooling the piston, save its contact with the walls of the
+cylinder and the slight air cooling of its back by its reciprocal
+motion. For this reason the concave piston-head has not been generally
+adopted and the concave cylinder-head, as shown in Fig. 19, with a
+flat piston-head is the latest and best practice in airplane engine
+construction.
+
+[Illustration: Fig. 20.--Mercedes Aviation Engine Cylinder Section
+Showing Approximately Spherical Combustion Chamber and Concave Piston
+Top.]
+
+The practical application of the principle just outlined to one of the
+most efficient airplane motors ever designed, the Mercedes, is clearly
+outlined at Fig. 20.
+
+
+HEAT LOSSES TO COOLING WATER
+
+The mean temperature of the wall surface of the combustion chamber and
+cylinder, as indicated by the temperatures of the circulating water, has
+been found to be an important item in the economy of the gas-engine.
+Dugald Clerk, in England, a high authority in practical work with the
+gas-engine, found that 10 per cent. of the gas for a stated amount of
+power was saved by using water at a temperature in which the ejected
+water from the cylinder-jacket was near the boiling-point, and ventures
+the opinion that a still higher temperature for the circulating water
+may be used as a source of economy. This could be made practical in the
+case of aviation engines by adjusting the air-cooling surface of the
+radiator so as to maintain the inlet water at just below the boiling
+point, and by the rapid circulation induced by the pump pressure, to
+return the water from the cylinder-jacket a few degrees above the
+boiling point. The thermal displacement systems of cooling employed in
+automobiles are working under more favorable temperature conditions than
+those engines in which cooling is more energetic.
+
+For a given amount of heat taken from the cylinder by the largest volume
+of circulating water, the difference in temperature between inlet and
+outlet of the water-jacket should be the least possible, and this
+condition of the water circulation gives a more even temperature to all
+parts of the cylinder; while, on the contrary, a cold-water supply, say
+at 60° F., so slow as to allow the ejected water to flow off at a
+temperature near the boiling-point, must make a great difference in
+temperature between the bottom and top of the cylinder, with a loss in
+economy in gas and other fuels, as well as in water, if it is obtained
+by measurement.
+
+From the foregoing considerations of losses and inefficiencies, we find
+that the practice in motor design and construction has not yet reached
+the desired perfection in its cycular operation. Step by step
+improvements have been made with many changes in design though many have
+been without merit as an improvement, farther than to gratify the
+longings of designers for something different from the other thing, and
+to establish a special construction of their own. These efforts may in
+time produce a motor of normal or standard design for each kind of fuel
+that will give the highest possible efficiency for all conditions of
+service.
+
+
+
+
+CHAPTER IV
+
+    Engine Parts and Functions--Why Multiple Cylinder Engines Are
+    Best--Describing Sequence of Operations--Simple Engines--Four
+    and Six Cylinder Vertical Tandem Engines--Eight and Twelve
+    Cylinder V Engines--Radial Cylinder Arrangement--Rotary Cylinder
+    Forms.
+
+
+ENGINE PARTS AND FUNCTIONS
+
+The principal elements of a gas engine are not difficult to understand
+and their functions are easily defined. In place of the barrel of the
+gun one has a smoothly machined cylinder in which a small cylindrical or
+barrel-shaped element fitting the bore closely may be likened to a
+bullet or cannon ball. It differs in this important respect, however, as
+while the shot is discharged from the mouth of the cannon the piston
+member sliding inside of the main cylinder cannot leave it, as its
+movements back and forth from the open to the closed end and back again
+are limited by simple mechanical connection or linkage which comprises
+crank and connection rod. It is by this means that the reciprocating
+movement of the piston is transformed into a rotary motion of the
+crank-shaft.
+
+The fly-wheel is a heavy member attached to the crank-shaft of an
+automobile engine which has energy stored in its rim as the member
+revolves, and the momentum of this revolving mass tends to equalize the
+intermittent pushes on the piston head produced by the explosion of the
+gas in the cylinder. In aviation engines, the weight of the propeller or
+that of rotating cylinders themselves performs the duty of a fly-wheel,
+so no separate member is needed. If some explosive is placed in the
+chamber formed by the piston and closed end of the cylinder and
+exploded, the piston would be the only part that would yield to the
+pressure which would produce a downward movement. As this is forced down
+the crank-shaft is turned by the connecting rod, and as this part is
+hinged at both ends it is free to oscillate as the crank turns, and thus
+the piston may slide back and forth while the crank-shaft is rotating or
+describing a curvilinear path.
+
+[Illustration: Fig. 21.--Side Sectional View of Typical Airplane Engine,
+Showing Parts and Their Relation to Each Other. This Engine is an
+Aeromarine Design and Utilizes a Distinctive Concentric Valve
+Construction.]
+
+In addition to the simple elements described it is evident that a
+gasoline engine must have other parts. The most important of these are
+the valves, of which there are generally two to each cylinder. One
+closes the passage connecting to the gas supply and opens during one
+stroke of the piston in order to let the explosive gas into the
+combustion chamber. The other member, or exhaust valve, serves as a
+cover for the opening through which the burned gases can leave the
+cylinder after their work is done. The spark plug is a simple device
+which may be compared to the fuse or percussion cap of the cannon. It
+permits one to produce an electric spark in the cylinder when the piston
+is at the best point to utilize the pressure which obtains when the
+compressed gas is fired. The valves are open one at a time, the inlet
+valve being lifted from its seat while the cylinder is filling and the
+exhaust valve is opened when the cylinder is being cleared. They are
+normally kept seated by means of compression springs. In the simple
+motor shown at Fig. 5, the exhaust valve is operated by means of a
+pivoted bell crank rocked by a cam which turns at half the speed of the
+crank-shaft. The inlet valve operates automatically, as will be
+explained in proper sequence.
+
+In order to obtain a perfectly tight combustion chamber, both intake and
+exhaust valves are closed before the gas is ignited, because all of the
+pressure produced by the exploding gas is to be directed against the top
+of the movable piston. When the piston reaches the bottom of its power
+stroke, the exhaust valve is lifted by means of the bell crank which is
+rocked because of the point or lift on the cam. The cam-shaft is driven
+by positive gearing and revolves at half the engine speed. The exhaust
+valve remains open during the whole of the return stroke of the piston,
+and as this member moves toward the closed end of the cylinder it
+forces out burned gases ahead of it, through the passage controlled by
+the exhaust valve. The cam-shaft is revolved at half the engine speed
+because the exhaust valve is raised from its seat during only one stroke
+out of four, or only once every two revolutions. Obviously, if the cam
+was turned at the same speed as the crank-shaft it would remain open
+once every revolution, whereas the burned gases are expelled from the
+individual cylinders only once in two turns of the crank-shaft.
+
+
+WHY MULTIPLE CYLINDER FORMS ARE BEST
+
+Owing to the vibration which obtains from the heavy explosion in the
+large single-cylinder engines used for stationary power other forms were
+evolved in which the cylinder was smaller and power obtained by running
+the engine faster, but these are suitable only for very low powers.
+
+When a single-cylinder engine is employed a very heavy fly-wheel is
+needed to carry the moving parts through idle strokes necessary to
+obtain a power impulse. For this reason automobile and aircraft
+designers must use more than one cylinder, and the tendency is to
+produce power by frequently occurring light impulses rather than
+by a smaller number of explosions having greater force. When a
+single-cylinder motor is employed the construction is heavier than is
+needed with a multiple-cylinder form. Using two or more cylinders
+conduces to steady power generation and a lessening of vibration. Most
+modern motor cars employ four-cylinder engines because a power impulse
+may be secured twice every revolution of the crank-shaft, or a total of
+four power strokes during two revolutions. The parts are so arranged
+that while the charge of gas in one cylinder is exploding, those which
+come next in firing order are compressing, discharging the inert gases
+and drawing in a fresh charge respectively. When the power stroke is
+completed in one cylinder, the piston in that member in which a charge
+of gas has just been compressed has reached the top of its stroke and
+when the gas is exploded the piston is reciprocated and keeps the
+crank-shaft turning. When a multiple-cylinder engine is used the
+fly-wheel can be made much lighter than that of the simpler form and
+eliminated altogether in some designs. In fact, many modern
+multiple-cylinder engines developing 300 horse-power weigh less than the
+early single- and double-cylinder forms which developed but one-tenth or
+one-twentieth that amount of energy.
+
+
+DESCRIBING SEQUENCE OF OPERATIONS
+
+Referring to Fig. 22, A, the sequence of operation in a single-cylinder
+motor can be easily understood. Assuming that the crank-shaft is turning
+in the direction of the arrow, it will be seen that the intake stroke
+comes first, then the compression, which is followed by the power
+impulse, and lastly the exhaust stroke. If two cylinders are used, it is
+possible to balance the explosions in such a way that one will occur
+each revolution. This is true with either one of two forms of four-cycle
+motors. At B, a two-cylinder vertical engine using a crank-shaft in
+which the crank-pins are on the same plane is shown. The two pistons
+move up and down simultaneously. Referring to the diagram describing the
+strokes, and assuming that the outer circle represents the cycle of
+operations in one cylinder while the inner circle represents the
+sequence of events in the other cylinder, while cylinder No. 1 is taking
+in a fresh charge of gas, cylinder No. 2 is exploding. When cylinder No.
+1 is compressing, cylinder No. 2 is exhausting. During the time that the
+charge in cylinder No. 1 is exploded, cylinder No. 2 is being filled
+with fresh gas. While the exhaust gases are being discharged from
+cylinder No. 1, cylinder No. 2 is compressing the gas previously taken.
+
+[Illustration: Fig. 22.--Diagrams Illustrating Sequence of Cycles in
+One- and Two-Cylinder Engines Showing More Uniform Turning Effort on
+Crank-Shaft with Two-Cylinder Motors.]
+
+The same condition obtains when the crank-pins are arranged at one
+hundred and eighty degrees and the cylinders are opposed, as shown at C.
+The reason that the two-cylinder opposed motor is more popular than
+that having two vertical cylinders is that it is difficult to balance
+the construction shown at B, so that the vibration will not be
+excessive. The two-cylinder opposed motor has much less vibration than
+the other form, and as the explosions occur evenly and the motor is a
+simple one to construct, it has been very popular in the past on light
+cars and has received limited application on some early, light
+airplanes.
+
+To demonstrate very clearly the advantages of multiple-cylinder engines
+the diagrams at Fig. 23 have been prepared. At A, a three-cylinder
+motor, having crank-pins at one hundred and twenty degrees, which means
+that they are spaced at thirds of the circle, we have a form of
+construction that gives a more even turning than that possible with a
+two-cylinder engine. Instead of one explosion per revolution of the
+crank-shaft, one will obtain three explosions in two revolutions. The
+manner in which the explosion strokes occur and the manner they overlap
+strokes in the other cylinder is shown at A. Assuming that the cylinders
+fire in the following order, first No. 1, then No. 2, and last No. 3, we
+will see that while cylinder No. 1, represented by the outer circle, is
+on the power stroke, cylinder No. 3 has completed the last two-thirds of
+its exhaust stroke and has started on its intake stroke. Cylinder No. 2,
+represented by the middle circle, during this same period has completed
+its intake stroke and two-thirds of its compression stroke. A study of
+the diagram will show that there is an appreciable lapse of time between
+each explosion.
+
+Three-cylinder engines are not used on aircraft at the present time,
+though Bleriot's flight across the British Channel was made with a
+three-cylinder Anzani motor. It was not a conventional form, however.
+The three-cylinder engine is practically obsolete at this time for any
+purpose except "penguins" or school machines that are incapable of
+flight and which are used in some French training schools for aviators.
+
+[Illustration: Fig. 23.--Diagrams Demonstrating Clearly Advantages which
+Obtain when Multiple-Cylinder Motors are Used as Power Plants.]
+
+
+FOUR- AND SIX-CYLINDER ENGINES
+
+In the four-cylinder engine operation which is shown at Fig. 23, B, it
+will be seen that the power strokes follow each other without loss of
+time, and one cylinder begins to fire and the piston moves down just as
+soon as the member ahead of it has completed its power stroke. In a
+four-cylinder motor, the crank-pins are placed at one hundred and eighty
+degrees, or on the halves of the crank circle. The crank-pins for
+cylinders No. 1 and No. 4 are on the same plane, while those for
+cylinders No. 2 and No. 3 also move in unison. The diagram describing
+sequence of operations in each cylinder is based on a firing order of
+one, two, four, three. The outer circle, as in previous instances,
+represents the cycle of operations in cylinder one. The next one toward
+the center, cylinder No. 2, the third circle represents the sequence of
+events in cylinder No. 3, while the inner circle outlines the strokes in
+cylinder four. The various cylinders are working as follows:
+
+      1.           2.           3.           4.
+
+  Explosion    Compression  Exhaust      Intake
+  Exhaust      Explosion    Intake       Compression
+  Intake       Exhaust      Compression  Explosion
+  Compression  Intake       Explosion    Exhaust
+
+It will be obvious that regardless of the method of construction, or the
+number of cylinders employed, exactly the same number of parts must be
+used in each cylinder assembly and one can conveniently compare any
+multiple-cylinder power plant as a series of single-cylinder engines
+joined one behind the other and so coupled that one will deliver power
+and produce useful energy at the crank-shaft where the other leaves off.
+The same fundamental laws governing the action of a single cylinder
+obtain when a number are employed, and the sequence of operation is the
+same in all members, except that the necessary functions take place at
+different times. If, for instance, all the cylinders of a four-cylinder
+motor were fired at the same time, one would obtain the same effect as
+though a one-piston engine was used, which had a piston displacement
+equal to that of the four smaller members. As is the case with a
+single-cylinder engine, the motor would be out of correct mechanical
+balance because all the connecting rods would be placed on crank-pins
+that lie in the same plane. A very large fly-wheel would be necessary to
+carry the piston through the idle strokes, and large balance weights
+would be fitted to the crank-shaft in an effort to compensate for the
+weight of the four pistons, and thus reduce vibratory stresses which
+obtain when parts are not in correct balance.
+
+There would be no advantage gained by using four cylinders in this
+manner, and there would be more loss of heat and more power consumed in
+friction than in a one-piston motor of the same capacity. This is the
+reason that when four cylinders are used the arrangement of crank-pins
+is always as shown at Fig. 23, B--i.e., two pistons are up, while the
+other two are at the bottom of the stroke. With this construction, we
+have seen that it is possible to string out the explosions so that there
+will always be one cylinder applying power to the crank-shaft. The
+explosions are spaced equally. The parts are in correct mechanical
+balance because two pistons are on the upstroke while the other two are
+descending. Care is taken to have one set of moving members weigh
+exactly the same as the other. With a four-cylinder engine one has
+correct balance and continuous application of energy. This insures a
+smoother running motor which has greater efficiency than the simpler
+one-, two-, and three-cylinder forms previously described. Eliminating
+the stresses which would obtain if we had an unbalanced mechanism and
+irregular power application makes for longer life. Obviously a large
+number of relatively light explosions will produce less wear and strain
+than would a lesser number of powerful ones. As the parts can be built
+lighter if the explosions are not heavy, the engine can be operated at
+higher rotative speeds than when large and cumbersome members are
+utilized. Four-cylinder engines intended for aviation work have been
+built according to the designs shown at Fig. 24, but these forms are
+unconventional and seldom if ever used.
+
+[Illustration: Fig. 24.--Showing Three Possible Though Unconventional
+Arrangements of Four-Cylinder Engines.]
+
+The six-cylinder type of motor, the action of which is shown at Fig. 23,
+C, is superior to the four-cylinder, inasmuch as the power strokes
+overlap, and instead of having two explosions each revolution we have
+three explosions. The conventional crank-shaft arrangement in a
+six-cylinder engine is just the same as though one used two
+three-cylinder shafts fastened together, so pistons 1 and 6 are on the
+same plane as are pistons 2 and 5. Pistons 3 and 4 also travel together.
+With the cranks arranged as outlined at Fig. 23, C, the firing order is
+one, five, three, six, two, four. The manner in which the power strokes
+overlap is clearly shown in the diagram. An interesting comparison is
+also made in the diagrams at Fig. 25 and in the upper corner of Fig. 23,
+C.
+
+[Illustration: Fig. 25.--Diagrams Outlining Advantages of Multiple
+Cylinder Motors, and Why They Deliver Power More Evenly Than Single
+Cylinder Types.]
+
+A rectangle is divided into four columns; each of these corresponds to
+one hundred and eighty degrees, or half a revolution. Thus the first
+revolution of the crank-shaft is represented by the first two columns,
+while the second revolution is represented by the last two. Taking the
+portion of the diagram which shows the power impulse in a one-cylinder
+engine, we see that during the first revolution there has been no power
+impulse. During the first half of the second revolution, however, an
+explosion takes place and a power impulse is obtained. The last portion
+of the second revolution is devoted to exhausting the burned gases, so
+that there are three idle strokes and but one power stroke. The effect
+when two cylinders are employed is shown immediately below.
+
+[Illustration: Fig. 26.--Diagrams Showing Duration of Events for a
+Four-Stroke Cycle, Six-Cylinder Engine.]
+
+Here we have one explosion during the first half of the first revolution
+in one cylinder and another during the first half of the second
+revolution in the other cylinder. With a four-cylinder engine there is
+an explosion each half revolution, while in a six-cylinder engine there
+is one and one-half explosions during each half revolution. When six
+cylinders are used there is no lapse of time between power impulses, as
+these overlap and a continuous and smooth-turning movement is imparted
+to the crank shaft. The diagram shown at Fig. 26, prepared by E. P.
+Pulley, can be studied to advantage in securing an idea of the
+coordination of effort that takes place in an engine of the six-cylinder
+type.
+
+
+ACTUAL DURATION OF DIFFERENT STROKES
+
+[Illustration: Fig. 27.--Diagram Showing Actual Duration of Different
+Strokes in Degrees.]
+
+In the diagrams previously presented the writer has assumed, for the
+sake of simplicity, that each stroke takes place during half of one
+revolution of the crank-shaft, which corresponds to a crank-pin travel
+of one hundred and eighty degrees. The actual duration of these strokes
+is somewhat different. For example, the inlet stroke is usually a trifle
+more than a half revolution, and the exhaust is always considerably
+more. The diagram showing the comparative duration of the strokes is
+shown at Fig. 27. The inlet valve opens ten degrees after the piston
+starts to go down and remains open thirty degrees after the piston has
+reached the bottom of its stroke. This means that the suction stroke
+corresponds to a crank-pin travel of two hundred degrees, while the
+compression stroke is measured by a movement of but one hundred and
+fifty degrees. It is common practice to open the exhaust valve before
+the piston reaches the end of the power stroke so that the actual
+duration of the power stroke is about one hundred and forty degrees,
+while the exhaust stroke corresponds to a crank-pin travel of two
+hundred and twenty-five degrees. In this diagram, which represents
+proper time for the valves to open and close, the dimensions in inches
+given are measured on the fly-wheel and apply only to a certain
+automobile motor. If the fly-wheel were smaller ten degrees would take
+up less than the dimensions given, while if the fly-wheel was larger a
+greater space on its circumference would represent the same crank-pin
+travel. Aviation engines are timed by using a timing disc attached to
+the crank-shaft as they are not provided with fly-wheels. Obviously, the
+distance measured in inches will depend upon the diameter of the disc,
+though the number of degrees interval would not change.
+
+[Illustration: Fig. 28.--Another Diagram to Facilitate Understanding
+Sequence of Functions in Six-Cylinder Engine.]
+
+
+EIGHT- AND TWELVE-CYLINDER V ENGINES
+
+Those who have followed the development of the gasoline engine will
+recall the arguments that were made when the six-cylinder motor was
+introduced at a time that the four-cylinder type was considered
+standard. The arrival of the eight-cylinder has created similar futile
+discussion of its practicability as this is so clearly established as to
+be accepted without question. It has been a standard power plant for
+aeroplanes for many years, early exponents having been the Antoinette,
+the Woolsley, the Renault, the E. N. V. in Europe and the Curtiss in the
+United States.
+
+[Illustration: Fig. 29.--Types of Eight-Cylinder Engines Showing the
+Advantage of the V Method of Cylinder Placing.]
+
+The reason the V type shown at Fig. 29, A is favored is that the
+"all-in-line form" which is shown at Fig. 29, B is not practical for
+aircraft because of its length. Compared to the standard four-cylinder
+engine it is nearly twice as long and it required a much stronger and
+longer crank-shaft. It will be evident that it could not be located to
+advantage in the airplane fuselage. These undesirable factors are
+eliminated in the V type eight-cylinder motor, as it consists of two
+blocks of four cylinders each, so arranged that one set or block is at
+an angle of forty-five degrees from the vertical center line of the
+motor, or at an angle of ninety degrees with the other set. This
+arrangement of cylinders produces a motor that is no longer than a
+four-cylinder engine of half the power would be.
+
+[Illustration: Fig. 30.--Curves Showing Torque of Various Engine Types
+Demonstrate Graphically Marked Advantage of the Eight-Cylinder Type.]
+
+Apparently there is considerable misconception as to the advantage of
+the two extra cylinders of the eight as compared with the six-cylinder.
+It should be borne in mind that the multiplication in the number of
+cylinders noticed since the early days of automobile development has not
+been for solely increasing the power of the engine, but to secure a more
+even turning movement, greater flexibility and to eliminate destructive
+vibration. The ideal internal combustion motor, is the one having the
+most uniform turning movement with the least mechanical friction loss.
+Study of the torque outlines or plotted graphics shown at Figs. 25 and
+30 will show how multiplication of cylinders will produce steady power
+delivery due to overlapping impulses. The most practical form would be
+that which more nearly conforms to the steady running produced by a
+steam turbine or electric motor. The advocates of the eight-cylinder
+engine bring up the item of uniform torque as one of the most important
+advantages of the eight-cylinder design. A number of torque diagrams are
+shown at Fig. 30. While these appear to be deeply technical, they may be
+very easily followed when their purpose is explained. At the top is
+shown the torque diagram of a single-cylinder motor of the four-cycle
+type. The high point in the line represents the period of greatest
+torque or power generation, and it will be evident that this occurs
+early in the first revolution of the crank-shaft. Below this diagram is
+shown a similar curve except that it is produced by a four-cylinder
+engine. Inspection will show that the turning-moment is much more
+uniform than in the single cylinder; similarly, the six-cylinder
+diagram is an improvement over the four, and the eight-cylinder diagram
+is an improvement over the six-cylinder.
+
+[Illustration: Fig. 31.--Diagrams Showing How Increasing Number of
+Cylinders Makes for More Uniform Power Application.]
+
+The reason that practically continuous torque is obtained in an
+eight-cylinder engine is that one cylinder fires every ninety degrees of
+crank-shaft rotation, and as each impulse lasts nearly seventy-five per
+cent. of the stroke, one can easily appreciate that an engine that will
+give four explosions per revolution of the crank-shaft will run more
+uniformly than one that gives but three explosions per revolution, as
+the six-cylinder does, and will be twice as smooth running as a
+four-cylinder, in which but two explosions occur per revolution of the
+crank-shaft. The comparison is so clearly shown in graphical diagrams
+and in Fig. 31 that further description is unnecessary.
+
+Any eight-cylinder engine may be considered a "twin-four,"
+twelve-cylinder engines may be considered "twin sixes."
+
+[Illustration: Fig. 32.--How the Angle Between the Cylinders of an
+Eight- and Twelve-Cylinder V Motor Varies.]
+
+The only points in which an eight-cylinder motor differs from a
+four-cylinder is in the arrangement of the connecting rod, as in many
+designs it is necessary to have two rods working from the same
+crank-pin. This difficulty is easily overcome in some designs by
+staggering the cylinders and having the two connecting rod big ends of
+conventional form side by side on a common crank-pin. In other designs
+one rod is a forked form and works on the outside of a rod of the
+regular pattern. Still another method is to have a boss just above the
+main bearing on one connecting rod to which the lower portion of the
+connecting rod in the opposite cylinder is hinged. As the eight-cylinder
+engine may actually be made lighter than the six-cylinder of equal
+power, it is possible to use smaller reciprocating parts, such as
+pistons, connecting rods and valve gear, and obtain higher engine speed
+with practically no vibration. The firing order in nearly every case is
+the same as in a four-cylinder except that the explosions occur
+alternately in each set of cylinders. The firing order of an
+eight-cylinder motor is apt to be confusing to the motorist,
+especially if one considers that there are eight possible sequences. The
+majority of engineers favor the alternate firing from side to side.
+Firing orders will be considered in proper sequence.
+
+[Illustration: Fig. 33.--The Hall-Scott Four-Cylinder 100 Horse-Power
+Aviation Motor.]
+
+[Illustration: Fig. 34.--Two Views of the Duesenberg Sixteen Valve
+Four-Cylinder Aviation Motor.]
+
+The demand of aircraft designers for more power has stimulated designers
+to work out twelve-cylinder motors. These are high-speed motors
+incorporating all recent features of design in securing light
+reciprocating parts, large valve openings, etc. The twelve-cylinder
+motor incorporates the best features of high-speed motor design and
+there is no need at this time to discuss further the pros and cons of
+the twelve-cylinder versus the eight or six, because it is conceded by
+all that there is the same degree of steady power application in the
+twelve over the eight as there would be in the eight over the six. The
+question resolves itself into having a motor of high power that will
+run with minimum vibration and that produces smooth action. This is well
+shown by diagrams at Fig. 31. It should be remembered that if an
+eight-cylinder engine will give four explosions per revolution of the
+fly-wheel, a twelve-cylinder type will give six explosions per
+revolution, and instead of the impulses coming 90 degrees crank travel
+apart, as in the case of the eight-cylinder, these will come but 60
+degrees of crank travel apart in the case of the twelve-cylinder. For
+this reason, the cylinders of a twelve are usually separated by 60
+degrees while the eight has the blocks spaced 90 degrees apart. The
+comparison can be easily made by comparing the sectional views of Vee
+engines at Fig. 32. When one realizes that the actual duration of the
+power stroke is considerably greater than 120 degrees crank travel, it
+will be apparent that the overlapping of explosions must deliver a very
+uniform application of power. Vee engines have been devised having the
+cylinders spaced but 45 degrees apart, but the explosions cannot be
+timed at equal intervals as when 90 degrees separate the cylinder center
+lines.
+
+[Illustration: Fig. 35.--The Hall-Scott Six-Cylinder Aviation Engine.]
+
+
+RADIAL CYLINDER ARRANGEMENTS
+
+[Illustration: Fig. 36.--The Curtiss Eight-Cylinder, 200 Horse-Power
+Aviation Engine.]
+
+While the fixed cylinder forms of engines, having the cylinders in
+tandem in the four- and six-cylinder models as shown at Figs. 33 to 35
+inclusive and the eight-cylinder V types as outlined at Figs. 36 and 37
+have been generally used and are most in favor at the present time,
+other forms of motors having unconventional cylinder arrangements have
+been devised, though most of these are practically obsolete. While many
+methods of decreasing weight and increasing mechanical efficiency of a
+motor are known to designers, one of the first to be applied to the
+construction of aeronautical power plants was an endeavor to group the
+components, which in themselves were not extremely light, into a form
+that would be considerably lighter than the conventional design. As an
+example, we may consider those multiple-cylinder forms in which the
+cylinders are disposed around a short crank-case, either radiating from
+a common center as at Fig. 38 or of the fan shape shown at Fig. 39. This
+makes it possible to use a crank-case but slightly larger than that
+needed for one or two cylinders and it also permits of a corresponding
+decrease in length of the crank-shaft. The weight of the engine is
+lessened because of the reduction in crank-shaft and crank-case weight
+and the elimination of a number of intermediate bearings and their
+supporting webs which would be necessary with the usual tandem
+construction. While there are six power impulses to every two
+revolutions of the crank-shaft, in the six-cylinder engine, they are
+not evenly spaced as is possible with the conventional arrangement.
+
+[Illustration: Fig. 37.--The Sturtevant Eight-Cylinder, High Speed
+Aviation Motor.]
+
+[Illustration: Fig. 38.--Anzani 40-50 Horse-Power Five-Cylinder Air
+Cooled Engine.]
+
+In the Anzani form, which is shown at Fig. 38, the crank-case is
+stationary and a revolving crank-shaft is employed as in conventional
+construction. The cylinders are five in number and the engine develops
+40 to 50 H.P. with a weight of 72 kilograms or 158.4 lbs. The cylinders
+are of the usual air-cooled form having cooling flanges only part of the
+way down the cylinder. By using five cylinders it is possible to have
+the power impulses come regularly, they coming 145° crank-shaft travel
+apart, the crank-shaft making two turns to every five explosions. The
+balance is good and power output regular. The valves are placed
+directly in the cylinder head and are operated by a common pushrod.
+Attention is directed to the novel method of installing the carburetor
+which supplies the mixture to the engine base from which inlet pipes
+radiate to the various cylinders. This engine is used on French school
+machines.
+
+[Illustration: Fig. 39.--Unconventional Six-Cylinder Aircraft Motor of
+Masson Design.]
+
+In the form shown at Fig. 39 six cylinders are used, all being placed
+above the crank-shaft center line. This engine is also of the air-cooled
+form and develops 50 H. P. and weighs 105 kilograms, or 231 lbs. The
+carburetor is connected to a manifold casting attached to the engine
+base from which the induction pipes radiate to the various cylinders.
+The propeller design and size relative to the engine is clearly shown in
+this view. While flights have been made with both of the engines
+described, this method of construction is not generally followed and has
+been almost entirely displaced abroad by the revolving motors or by the
+more conventional eight-cylinder V engines. Both of the engines shown
+were designed about eight years ago and would be entirely too small and
+weak for use in modern airplanes intended for active duty.
+
+
+ROTARY ENGINES
+
+[Illustration: Fig. 40.--The Gnome Fourteen-Cylinder Revolving Motor.]
+
+Rotary engines such as shown at Fig. 40 are generally associated with
+the idea of light construction and it is rather an interesting point
+that is often overlooked in connection with the application of this idea
+to flight motors, that the reason why rotary engines are popularly
+supposed to be lighter than the others is because they form their own
+fly-wheel, yet on aeroplanes, engines are seldom fitted with a fly-wheel
+at all. As a matter of fact the Gnome engine is not so light because it
+is a rotary motor, and it is a rotary motor because the design that has
+been adopted as that most conducive to lightness is also most suited to
+an engine working in this way. The cylinders could be fixed and
+crank-shaft revolve without increasing the weight to any extent. There
+are two prime factors governing the lightness of an engine, one being
+the initial design, and the other the quality of the materials employed.
+The consideration of reducing weight by cutting away metal is a
+subsidiary method that ought not to play a part in standard practice,
+however useful it may be in special cases. In the Gnome rotary engine
+the lightness is entirely due to the initial design and to the materials
+employed in manufacture. Thus, in the first case, the engine is a radial
+engine, and has its seven or nine cylinders spaced equally around a
+crank-chamber that is no wider or rather longer than would be required
+for any one of the cylinders. This shortening of the crank-chamber not
+only effects a considerable saving of weight on its own account, but
+there is a corresponding saving in the shafts and other members, the
+dimensions of which are governed by the size of the crank-chamber. With
+regard to materials, nothing but steel is used throughout, and most of
+the metal is forged chrome nickel steel. The beautifully steady running
+of the engine is largely due to the fact that there are literally no
+reciprocating parts in the absolute sense, the apparent reciprocation
+between the pistons and cylinders being solely a relative reciprocation
+since both travel in circular paths, that of the pistons, however, being
+electric by one-half of the stroke length to that of the cylinder.
+
+While the Gnome engine has many advantages, on the other hand the head
+resistance offered by a motor of this type is considerable; there is a
+large waste of lubricating oil due to the centrifugal force which tends
+to throw the oil away from the cylinders; the gyroscopic effect of the
+rotary motor is detrimental to the best working of the aeroplane, and
+moreover it requires about seven per cent. of the total power developed
+by the motor to drive the revolving cylinders around the shaft. Of
+necessity, the compression of this type of motor is rather low, and an
+additional disadvantage manifests itself in the fact that there is as
+yet no satisfactory way of muffling the rotary type of motor. The modern
+Gnome engine has been widely copied in various European countries, but
+its design was originated in America, the early Adams-Farwell engine
+being the pioneer form. It has been made in seven- and nine-cylinder
+types and forms of double these numbers. The engine illustrated at Fig.
+40 is a fourteen-cylinder form. The simple engines have an odd number of
+cylinders in order to secure evenly spaced explosions. In the
+seven-cylinder, the impulses come 102.8° apart. In the nine-cylinder
+form, the power strokes are spaced 80° apart. The fourteen-cylinder
+engine is virtually two seven-cylinder types mounted together, the
+cranks being just the same as in a double cylinder opposed motor, the
+explosions coming 51.4° apart; while in the eighteen-cylinder model the
+power impulses come every 40° cylinder travel. Other rotary motors have
+been devised, such as the Le Rhone and the Clerget in France and several
+German copies of these various types. The mechanical features of these
+motors will be fully considered later.
+
+
+
+
+CHAPTER V
+
+    Properties of Liquid Fuels--Distillates of Crude Petroleum--
+    Principles of Carburetion Outlined--Air Needed to Burn Gasoline
+    --What a Carburetor Should Do--Liquid Fuel Storage and Supply--
+    Vacuum Fuel Feed--Early Vaporizer Forms--Development of Float
+    Feed Carburetor--Maybach's Early Design--Concentric Float and
+    Jet Type--Schebler Carburetor--Claudel Carburetor--Stewart
+    Metering Pin Type--Multiple Nozzle Vaporizers--Two-Stage
+    Carburetor--Master Multiple Jet Type--Compound Nozzle Zenith
+    Carburetor--Utility of Gasoline Strainers--Intake Manifold
+    Design and Construction--Compensating for Various Atmospheric
+    Conditions--How High Altitude Affects Power--The Diesel System--
+    Notes on Carburetor Installation--Notes on Carburetor
+    Adjustment.
+
+
+There is no appliance that has more material value upon the efficiency
+of the internal combustion motor than the carburetor or vaporizer which
+supplies the explosive gas to the cylinders. It is only in recent years
+that engineers have realized the importance of using carburetors that
+are efficient and that are so strongly and simply made that there will
+be little liability of derangement. As the power obtained from the
+gas-engine depends upon the combustion of fuel in the cylinders, it is
+evident that if the gas supplied does not have the proper proportions of
+elements to insure rapid combustion the efficiency of the engine will be
+low. When a gas engine is used as a stationary installation it is
+possible to use ordinary illuminating or natural gas for fuel, but when
+this prime mover is applied to automobiles or airplanes it is evident
+that considerable difficulty would be experienced in carrying enough
+compressed coal gas to supply the engine for even a very short trip.
+Fortunately, the development of the internal-combustion motor was not
+delayed by the lack of suitable fuel.
+
+Engineers were familiar with the properties of certain liquids which
+gave off vapors that could be mixed with air to form an explosive gas
+which burned very well in the engine cylinders. A very small quantity of
+such liquids would suffice for a very satisfactory period of operation.
+The problem to be solved before these liquids could be applied in a
+practical manner was to evolve suitable apparatus for vaporizing them
+without waste. Among the liquids that can be combined with air and
+burned, gasoline is the most volatile and is the fuel utilized by
+internal-combustion engines.
+
+The widely increasing scope of usefulness of the internal-combustion
+motor has made it imperative that other fuels be applied in some
+instances because the supply of gasoline may in time become inadequate
+to supply the demand. In fact, abroad this fuel sells for fifty to two
+hundred per cent. more than it does in America because most of the
+gasoline used must be imported from this country or Russia. Because of
+this foreign engineers have experimented widely with other substances,
+such as alcohol, benzol, and kerosene, but more to determine if they can
+be used to advantage in motor cars than in airplane engines.
+
+
+DISTILLATES OF CRUDE PETROLEUM
+
+Crude petroleum is found in small quantities in almost all parts of the
+world, but a large portion of that produced commercially is derived from
+American wells. The petroleum obtained in this country yields more of
+the volatile products than those of foreign production, and for that
+reason the demand for it is greater. The oil fields of this country are
+found in Pennsylvania, Indiana, and Ohio, and the crude petroleum is
+usually in association with natural gas. This mineral oil is an agent
+from which many compounds and products are derived, and the products
+will vary from heavy sludges, such as asphalt, to the lighter and more
+volatile components, some of which will evaporate very easily at
+ordinary temperatures.
+
+The compounds derived from crude petroleum are composed principally of
+hydrogen and carbon and are termed "Hydrocarbons." In the crude product
+one finds many impurities, such as free carbon, sulphur, and various
+earthy elements. Before the oil can be utilized it must be subjected to
+a process of purifying which is known as refining, and it is during this
+process, which is one of destructive distillation, that the various
+liquids are separated. The oil was formerly broken up into three main
+groups of products as follows: Highly volatile, naphtha, benzine,
+gasoline, eight to ten per cent. Light oils, such as kerosene and light
+lubricating oils seventy to eighty per cent. Heavy oils or residuum five
+to nine per cent. From the foregoing it will be seen that the available
+supply of gasoline is determined largely by the demand existing for the
+light oils forming the larger part of the products derived from crude
+petroleum. New processes have been recently discovered by which the
+lighter oils, such as kerosene, are reduced in proportion and that of
+gasoline increased, though the resulting liquid is neither the high
+grade, volatile gasoline known in the early days of motoring nor the low
+grade kerosene.
+
+
+PRINCIPLES OF CARBURETION OUTLINED
+
+The process of carburetion is combining the volatile vapors which
+evaporate from the hydrocarbon liquids with certain proportions of air
+to form an inflammable gas. The quantities of air needed vary with
+different liquids and some mixtures burn quicker than do other
+combinations of air and vapor. Combustion is simply burning and it may
+be rapid, moderate or slow. Mixtures of gasoline and air burn quickly,
+in fact the combustion is so rapid that it is almost instantaneous and
+we obtain what is commonly termed an "explosion." Therefore the
+explosion of gas in the automobile engine cylinder which produces the
+power is really a combination of chemical elements which produce heat
+and an increase in the volume of the gas because of the increase in
+temperature.
+
+If the gasoline mixture is not properly proportioned the rate of
+burning will vary, and if the mixture is either too rich or too weak the
+power of the explosion is reduced and the amount of power applied to the
+piston is decreased proportionately. In determining the proper
+proportions of gasoline and air, one must take the chemical composition
+of gasoline into account. The ordinary liquid used for fuel is said to
+contain about eight-four per cent. carbon and sixteen per cent.
+hydrogen. Air is composed of oxygen and nitrogen and the former has a
+great affinity, or combining power, with the two constituents of
+hydrocarbon liquids. Therefore, what we call an explosion is merely an
+indication that oxygen in the air has combined with the carbon and
+hydrogen of the gasoline.
+
+
+AIR NEEDED TO BURN GASOLINE
+
+In figuring the proper volume of air to mix with a given quantity of
+fuel, one takes into account the fact that one pound of hydrogen
+requires eight pounds of oxygen to burn it, and one pound of carbon
+needs two and one-third pounds of oxygen to insure its combustion. Air
+is composed of one part of oxygen to three and one-half portions of
+nitrogen by weight. Therefore for each pound of oxygen one needs to burn
+hydrogen or carbon four and one-half pounds of air must be allowed. To
+insure combustion of one pound of gasoline which is composed of hydrogen
+and carbon we must furnish about ten pounds of air to burn the carbon
+and about six pounds of air to insure combustion of hydrogen, the other
+component of gasoline. This means that to burn one pound of gasoline one
+must provide about sixteen pounds of air.
+
+While one does not usually consider air as having much weight, at a
+temperature of sixty-two degrees Fahrenheit about fourteen cubic feet of
+air will weigh a pound, and to burn a pound of gasoline one would
+require about two hundred cubic feet of air. This amount will provide
+for combustion theoretically, but it is common practice to allow twice
+this amount because the element nitrogen, which is the main constituent
+of air, is an inert gas and instead of aiding combustion it acts as a
+deterrent of burning. In order to be explosive, gasoline vapor must be
+combined with definite quantities of air. Mixtures that are rich in
+gasoline ignite quicker than those which have more air, but these are
+only suitable when starting or when running slowly, as a rich mixture
+ignites much quicker than a weak mixture. The richer mixture of gasoline
+and air not only burns quicker but produces the most heat and the most
+effective pressure in pounds per square inch of piston top area.
+
+The amount of compression of the charge before ignition also has
+material bearing on the force of the explosion. The higher the degree of
+compression the greater the force exerted by the rapid combustion of the
+gas. It may be stated that as a general thing the maximum explosive
+pressure is somewhat more than four times the compression pressure prior
+to ignition. A charge compressed to sixty pounds will have a maximum of
+approximately two hundred and forty pounds; compacted to eighty pounds
+it will produce a pressure of about three hundred pounds on each square
+inch of piston area at the beginning of the power stroke. Mixtures
+varying from one part of gasoline vapor to four of air to others having
+one part of gasoline vapor to thirteen of air can be ignited, but the
+best results are obtained when the proportions are one to five or one to
+seven, as this mixture is said to be the one that will produce the
+highest temperature, the quickest explosion, and the most pressure.
+
+
+WHAT A CARBURETOR SHOULD DO
+
+While it is apparent that the chief function of a carbureting device is
+to mix hydrocarbon vapors with air to secure mixtures that will burn,
+there are a number of factors which must be considered before describing
+the principles of vaporizing devices. Almost any device which permits a
+current of air to pass over or through a volatile liquid will produce a
+gas which will explode when compressed and ignited in the motor
+cylinder. Modern carburetors are not only called upon to supply certain
+quantities of gas, but these must deliver a mixture to the cylinders
+that is accurately proportioned and which will be of proper composition
+at all engine speeds.
+
+[Illustration: Fig. 41.--How Gravity Feed Fuel Tank May Be Mounted Back
+of Engine and Secure Short Fuel Line.]
+
+Flexible control of the engine is sought by varying the engine speed by
+regulating the supply of gas to the cylinders. The power plant should
+run from its lowest to its highest speed without any irregularity in
+torque, i.e., the acceleration should be gradual rather than spasmodic.
+As the degree of compression will vary in value with the amount of
+throttle opening, the conditions necessary to obtain maximum power
+differ with varying engine speeds. When the throttle is barely opened
+the engine speed is low and the gas must be richer in fuel than when the
+throttle is wide open and the engine speed high.
+
+When an engine is turning over slowly the compression has low value and
+the conditions are not so favorable to rapid combustion as when the
+compression is high. At high engine speeds the gas velocity through the
+intake piping is higher than at low speeds, and regular engine action is
+not so apt to be disturbed by condensation of liquid fuel in the
+manifold due to excessively rich mixture or a superabundance of liquid
+in the stream of carbureted air.
+
+
+LIQUID FUEL STORAGE AND SUPPLY
+
+The problem of gasoline storage and method of supplying the carburetor
+is one that is determined solely by design of the airplane. While the
+object of designers should be to supply the fuel to the carburetor by as
+simple means as possible the fuel supply system of some airplanes is
+quite complex. The first point to consider is the location of the
+gasoline tank. This depends upon the amount of fuel needed and the space
+available in the fuselage.
+
+A very simple and compact fuel supply system is shown at Fig. 41. In
+this instance the fuel container is placed immediately back of the
+engine cylinder. The carburetor which is carried as indicated is joined
+to the tank by a short piece of copper or flexible rubber tubing. This
+is the simplest possible form of fuel supply system and one used on a
+number of excellent airplanes.
+
+As the sizes of engines increase and the power plant fuel consumption
+augments it is necessary to use more fuel, and to obtain a satisfactory
+flying radius without frequent landings for filling the fuel tank it is
+necessary to supply large containers.
+
+When a very powerful power plant is fitted, as on battle planes of high
+capacity, it is necessary to carry large quantities of gasoline. In
+order to use a tank of sufficiently large capacity it may be necessary
+to carry it lower than the carburetor. When installed in this manner it
+is necessary to force fuel out of the tank by air pressure or to pump it
+with a vacuum tank because the gasoline tank is lower than the
+carburetor it supplies and the gasoline cannot flow by gravity as in the
+simpler systems. While the pressure and gravity feed systems are
+generally used in airplanes, it may be well to describe the vacuum lift
+system which has been widely applied to motor cars and which may have
+some use in connection with airplanes as these machines are developed.
+
+
+STEWART VACUUM FUEL FEED
+
+One of the marked tendencies has been the adoption of a vacuum fuel feed
+system to draw the gasoline from tanks placed lower than the carburetor
+instead of using either exhaust gas or air pressure to achieve this end.
+The device generally fitted is the Stewart vacuum feed tank which is
+clearly shown in section at Fig. 42. In this system the suction of a
+motor is employed to draw gasoline from the main fuel tank to the
+auxiliary tank incorporated in the device and from this tank the liquid
+flows to the carburetor. It is claimed that all the advantages of the
+pressure system are obtained with very little more complication than is
+found on the ordinary gravity feed. The mechanism is all contained in
+the cylindrical tank shown, which may be mounted either on the front of
+the dash or on the side of the engine as shown.
+
+[Illustration: Fig. 42.--The Stewart Vacuum Fuel Feed Tank.]
+
+The tank is divided into two chambers, the upper one being the filling
+chamber and the lower one the emptying chamber. The former, which is at
+the top of the device, contains the float valve, as well as the pipes
+running to the main fuel container and to the intake manifold. The lower
+chamber is used to supply the carburetor with gasoline and is under
+atmospheric pressure at all times, so the flow of fuel from it is by
+means of gravity only. Since this chamber is located somewhat above the
+carburetor, there must always be free flow of fuel. Atmospheric pressure
+is maintained by the pipes A and B, the latter opening into the air. In
+order that the fuel will be sucked from a main tank to the upper
+chamber, the suction valve must be opened and the atmospheric valve
+closed. Under these conditions the float is at the bottom and the
+suction at the intake manifold produces a vacuum in the tank which draws
+the gasoline from the main tank to the upper chamber. When the upper
+chamber is filled at the proper height the float rises to the top, this
+closing the suction valve and opening the atmospheric valve. As the
+suction is now cut off, the lower chamber is filled by gravity owing to
+there being atmospheric pressure in both upper and lower chambers. A
+flap valve is provided between the two chambers to prevent the gasoline
+in the lower one from being sucked back into the upper one. The
+atmospheric and suction valves are controlled by the levers C and D,
+both of which are pivoted at E, their outer ends being connected by two
+coil springs. It is seen that the arrangement of these two springs is
+such that the float must be held at the extremity of its movement, and
+that it cannot assume an intermediate position.
+
+This intermittent action is required to insure that the upper part of
+the tank may be under atmospheric pressure part of the time for the
+gasoline to flow to the lower chamber. When the level of gasoline drops
+to a certain point, the float falls, thus opening the suction valve and
+closing the atmospheric valve. The suction of the motor then causes a
+flow of fuel from the main container. As soon as the level rises to the
+proper height the float returns to its upper position. It takes about
+two seconds for the chamber to become full enough to raise the float, as
+but .05 gallon is transferred at a time. The pipe running from the
+bottom of the lower chamber to the carburetor extends up a ways, so that
+there is but little chance of dirt or water being carried to the float
+chamber.
+
+If the engine is allowed to stand long enough so that the tank becomes
+empty, it will be replenished after the motor has been cranked over four
+or five times with the throttle closed. The installation of the Stewart
+Vacuum-Gravity System is very simple. The suction pipe is tapped into
+the manifold at a point as near the cylinders as possible, while the
+fuel pipe is inserted into the gasoline tank and runs to the bottom of
+that member. There is a screen at the end of the fuel pipe to prevent
+any trouble due to deposits of sediment in the main container. As the
+fuel is sucked from the gasoline tank a small vent must be made in the
+tank filler cap so that the pressure in the main tank will always be
+that of the atmosphere.
+
+
+EARLY VAPORIZER FORMS
+
+The early types of carbureting devices were very crude and cumbersome,
+and the mixture of gasoline vapor and air was accomplished in three
+ways. The air stream was passed over the surface of the liquid itself,
+through loosely placed absorbent material saturated with liquid, or
+directly through the fuel. The first type is known as the surface
+carburetor and is now practically obsolete. The second form is called
+the "wick" carburetor because the air stream was passed over or through
+saturated wicking. The third form was known as a "bubbling" carburetor.
+While these primitive forms gave fairly good results with the early
+slow-speed engines and the high grade, or very volatile, gasoline which
+was first used for fuel, they would be entirely unsuitable for present
+forms of engines because they would not carburate the lower grades of
+gasoline which are used to-day, and would not supply the modern
+high-speed engines with gas of the proper consistency fast enough even
+if they did not have to use very volatile gasoline. The form of
+carburetor used at the present time operates on a different principle.
+These devices are known as "spraying carburetors." The fuel is reduced
+to a spray by the suction effect of the entering air stream drawing it
+through a fine opening.
+
+The advantage of this construction is that a more thorough amalgamation
+of the gasoline and air particles is obtained. With the earlier types
+previously considered the air would combine with only the more volatile
+elements, leaving the heavier constituents in the tank. As the fuel
+became stale it was difficult to vaporize it, and it had to be drained
+off and fresh fuel provided before the proper mixture would be produced.
+It will be evident that when the fuel is sprayed into the air stream,
+all the fuel will be used up and the heavier portions of the gasoline
+will be taken into the cylinder and vaporized just as well as the more
+volatile vapors.
+
+[Illustration: Fig. 43.--Marine-Type Mixing Valve, by which Gasoline is
+Sprayed into Air Stream Through Small Opening in Air-Valve Seat.]
+
+The simplest form of spray carburetor is that shown at Fig. 43. In this
+the gasoline opening through which the fuel is sprayed into the
+entering air stream is closed by the spring-controlled mushroom valve
+which regulates the main air opening as well. When the engine draws in a
+charge of air it unseats the valve and at the same time the air flowing
+around it is saturated with gasoline particles through the gasoline
+opening. The mixture thus formed goes to the engine through the mixture
+passage. Two methods of varying the fuel proportions are provided. One
+of these consists of a needle valve to regulate the amount of gasoline,
+the other is a knurled screw which controls the amount of air by
+limiting the lift of the jump valve.
+
+
+DEVELOPMENT OF FLOAT-FEED CARBURETOR
+
+The modern form of spraying carburetor is provided with two chambers,
+one a mixing chamber through which the air stream passes and mixes with
+a gasoline spray, the other a float chamber in which a constant level of
+fuel is maintained by simple mechanism. A jet or standpipe is used in
+the mixing chamber to spray the fuel through and the object of the float
+is to maintain the fuel level to such a point that it will not overflow
+the jet when the motor is not drawing in a charge of gas. With the
+simple forms of generator valve in which the gasoline opening is
+controlled by the air valve, a leak anywhere in either valve or valve
+seat will allow the gasoline to flow continuously whether the engine is
+drawing in a charge or not. The liquid fuel collects around the air
+opening, and when the engine inspires a charge it is saturated with
+gasoline globules and is excessively rich. With a float-feed
+construction, which maintains a constant level of gasoline at the right
+height in the standpipe, liquid fuel will only be supplied when drawn
+out of the jet by the suction effect of the entering air stream.
+
+
+MAYBACH'S EARLY DESIGN
+
+The first form of spraying carburetor ever applied successfully was
+evolved by Maybach for use on one of the earliest Daimler engines. The
+general principles of operation of this pioneer float-feed carburetor
+are shown at Fig. 44, A. The mixing chamber and valve chamber were one
+and the standpipe or jet protruded into the mixing chamber. It was
+connected to the float compartment by a pipe. The fuel from the tank
+entered the top of the float compartment and the opening was closed by a
+needle valve carried on top of a hollow metal float. When the level of
+gasoline in the float chamber was lowered the float would fall and the
+needle valve uncover the opening. This would permit the gasoline from
+the tank to flow into the float chamber, and as the chamber filled the
+float would rise until the proper level had been reached, under which
+conditions the float would shut off the gasoline opening. On every
+suction stroke of the engine the inlet valve, which was an automatic
+type, would leave its seat and a stream of air would be drawn through
+the air opening and around the standpipe or jet. This would cause the
+gasoline to spray out of the tube and mix with the entering air stream.
+
+[Illustration: Fig. 44.--Tracing Evolution of Modern Spray Carburetor.
+A--Early Form Evolved by Maybach. B.--Phoenix-Daimler Modification of
+Maybach's Principle. C--Modern Concentric Float Automatic Compensating
+Carburetor.]
+
+The form shown at B was a modification of Maybach's simple device and
+was first used on the Phoenix-Daimler engines. Several improvements are
+noted in this device. First, the carburetor was made one unit by casting
+the float and mixing chambers together instead of making them separate
+and joining them by a pipe, as shown at A. The float construction was
+improved and the gasoline shut-off valve was operated through leverage
+instead of being directly fastened to the float. The spray nozzle was
+surrounded by a choke tube which concentrated the air stream around it
+and made for more rapid air flow at low engine speeds. A conical piece
+was placed over the jet to break up the entering spray into a mist and
+insure more intimate admixture of air and gasoline. The air opening was
+provided with an air cone which had a shutter controlling the opening so
+that the amount of air entering could be regulated and thus vary the
+mixture proportions within certain limits.
+
+
+CONCENTRIC FLOAT AND JET TYPE
+
+The form shown at B has been further improved, and the type shown at C
+is representative of modern single jet practice. In this the float
+chamber and mixing chamber are concentric. A balanced float mechanism
+which insures steadiness of feed is used, the gasoline jet or standpipe
+is provided with a needle valve to vary the amount of gasoline supplied
+the mixture and two air openings are provided. The main air port is at
+the bottom of the vaporizer, while an auxiliary air inlet is provided at
+the side of the mixing chamber. There are two methods of controlling the
+mixture proportions in this form of carburetor. One may regulate the
+gasoline needle or adjust the auxiliary air valve.
+
+
+SCHEBLER CARBURETOR
+
+A Schebler carburetor, which has been used on some airplane engines, is
+shown in Fig. 45. It will be noticed that a metering pin or needle valve
+opens the jet when the air valve opens. The long arm of a leverage is
+connected to the air valve, while the short arm is connected to the
+needle, the reduction in leverage being such that the needle valve is
+made to travel much less than the air valve. For setting the amount of
+fuel passed or the size of the jet orifice when running with the air
+valve closed, there is a screw which raises or lowers the fulcrum of the
+lever and there is also a dash control having the same effect by pushing
+down the fulcrum against a small spring. A long extension is given to
+the venturi tube which is very narrow around the jet orifices, which are
+horizontal and shown at A in the drawing. Fuel enters the float chamber
+through the union M, and the spring P holds the metering pin upward
+against the restraining action of the lever. The air valve may be set by
+an easily adjustable knurled screw shown in the drawing, and fluttering
+of the valve is prevented by the piston dash pot carried in a chamber
+above the valve into which the valve stem projects. The primary air
+enters beneath the jet passage and there is a small throttle in the
+intake to increase the speed of air flow for starting purposes. The
+carburetor is adapted for the use of a hot-air connection to the stove
+around the exhaust pipe and it is recommended that such a fitting be
+supplied. The lever which controls the supply of air through the primary
+air intake is so arranged that if desired it can be connected with a
+linkage on the dash or control column by means of a flexible wire.
+
+[Illustration: Fig. 45.--New Model of Schebler Carburetor With Metering
+Valve and Extended Venturi. Note Mechanical Connection Between Air Valve
+and Fuel Regulating Needle.]
+
+
+THE CLAUDEL (FRENCH) CARBURETOR
+
+[Illustration: Fig. 46.--The Claudel Carburetor.]
+
+This carburetor is of extremely simple construction, because it has no
+supplementary or auxiliary air valve and no moving parts except the
+throttle controlling the gas flow. The construction is already shown in
+Fig. 46. The spray jet is eccentric with a surrounding sleeve or tube
+in which there are two series of small orifices, one at the top and the
+other near the bottom. The former are about level with the spray jet
+opening. The sleeve surrounding the nozzle is closed at the top. The
+air, passing the upper holes in the sleeve, produces a vacuum in the
+sleeve, thereby drawing air in through the bottom holes. It is this
+moving interior column of air that controls the flow of gasoline from
+the nozzle. Owing to the friction of the small passages, the speed of
+air flow through the sleeve does not increase as fast as the speed of
+air flow outside the sleeve, hence there is a tendency for the mixture
+to remain constant. The throttle of this carburetor is of the barrel
+type, and the top of the spray nozzle and its surrounding sleeve are
+located inside the throttle.
+
+
+STEWART METERING PIN CARBURETOR
+
+The carburetor shown at Fig. 47 is a metering type in which the vacuum
+at the jet is controlled by the weight of the metering valve surrounding
+the upright metering pin. The only moving part is the metering valve,
+which rises and falls with the changes in vacuum. The air chamber
+surrounds the metering valve, and there is a mixing chamber above. As
+the valve is drawn up the gasoline passage is enlarged on account of the
+predetermined taper on the metering pin, and the air passage also is
+increased proportionately, giving the correct mixture. A dashpot at the
+bottom of the valve checks flutter. In idling the valve rests on its
+seat, practically closing the air and giving the necessary idling
+mixture. A passage through the valve acts as an aspirating tube. When
+the valve is closed altogether the primary air passes through ducts in
+the valve itself, giving the proper amount for idling. The one
+adjustment consists in raising or lowering the tapered metering pin,
+increasing or decreasing the supply of gasoline. Dash control is
+supplied. This pulls down the metering pin, increasing the gasoline
+flow. The duplex type for eight- and twelve-cylinder motors is the same
+in principle as model 25, but it is a double carburetor synchronized as
+to throttle movements, adjustments, etc. The duplex for aeronautical
+motors is made of cast aluminum alloy.
+
+[Illustration: Fig. 47.--The Stewart Metering Pin Carburetor.]
+
+
+MULTIPLE NOZZLE VAPORIZERS
+
+To secure properly proportioned mixtures some carburetor designers have
+evolved forms in which two or more nozzles are used in a common mixing
+chamber. The usual construction is to use two, one having a small
+opening and placed in a small air tube and used only for low speeds,
+the other being placed in a larger air tube and having a slightly
+augmented bore so that it is employed on intermediate speeds. At high
+speeds both jets would be used in series. Some multiple jet carburetors
+could be considered as a series of these instruments, each one being
+designed for certain conditions of engine action. They would vary from
+small size just sufficient to run the engine at low speed to others
+having sufficient capacity to furnish gas for the highest possible
+engine speed when used in conjunction with the smaller members which
+have been brought into service progressively as the engine speed has
+been augmented. The multiple nozzle carburetor differs from that in
+which a single spray tube is used only in the construction of the mixing
+chamber, as a common float bowl can be used to supply all spray pipes.
+It is common practice to bring the jets into action progressively by
+some form of mechanical connection with the throttle or by automatic
+valves.
+
+The object of any multiple nozzle carburetor is to secure greater
+flexibility and endeavor to supply mixtures of proper proportions at all
+speeds of the engine. It should be stated, however, that while devices
+of this nature lend themselves readily to practical application it is
+more difficult to adjust them than the simpler forms having but one
+nozzle. When a number of jets are used the liability of clogging up the
+carburetor is increased, and if one or more of the nozzles is choked by
+a particle of dirt or water the resulting mixture trouble is difficult
+to detect. One of the nozzles may supply enough gasoline to permit the
+engine to run well at certain speeds and yet not be adequate to supply
+the proper amount of gas under other conditions. In adjusting a multiple
+jet carburetor in which the jets are provided with gasoline regulating
+needles, it is customary to consider each nozzle as a distinct
+carburetor and to regulate it to secure the best motor action at that
+throttle position which corresponds to the conditions under which the
+jet is brought into service. For instance, that supplied the primary
+mixing chamber should be regulated with the throttle partly closed,
+while the auxiliary jet should be adjusted with the throttle fully
+opened.
+
+
+BALL AND BALL TWO-STAGE CARBURETOR
+
+[Illustration: Fig. 48.--The Ball and Ball Two-Stage Carburetor.]
+
+This is a two-stage vaporizing device, hot air being used in the primary
+or initial stage of vaporization and cold air in the supplementary
+stage. Referring to the sectional illustration at Fig. 48, it will be
+seen that there is a hot-air passage with a choke-valve; the primary
+venturi appears at B; J is its gasoline jet, and V is a spring-loaded
+idling valve in a fixed air opening. These parts constitute the primary
+system. In the secondary system A is a cold-air passage, T a butterfly
+valve and J a gasoline jet discharging into the cold-air passage. This
+system is brought into operation by opening the butterfly T. A
+connection between the butterfly T and the throttle, not shown, throws
+the butterfly wide open when the throttle is not quite wide open; at all
+other times the butterfly is held closed by a spring. The cylindrical
+chamber at the right of the mixing chamber has an extension E of reduced
+diameter connecting it with the intake manifold through a passage D. A
+restricted opening connects the float chamber with the cylindrical
+chamber so that the gasoline level is the same in both. A loosely
+fitting plunger P in the cylindrical chamber has an upward extension
+into the small part of the chamber. O is a small air opening and M is a
+passage from the cylindrical chamber to the mixing chamber. Air
+constantly passes through this when the carburetor is in operation. The
+carburetor is really two in one. The primary carburetor is made up of a
+central jet in a venturi passage. The float chamber is eccentric. In the
+air passage there is a fixed opening, and additional air is taken in by
+the opening through suction of a spring-opposed air valve. The second
+stage, which comes into play as soon as the carburetor is called upon
+for additional mixture above low medium speeds, is made up of an
+independent air passage containing another air valve. As the valve is
+opened this jet is uncovered, and air is led past it. For easy starting
+an extra passage leads from the float bowl passage to a point above the
+throttle. All the suction falls upon this passage when the throttle is
+closed. The passage contains a plunger and acts as a pick-up device.
+When the vacuum increases the plunger rises and shuts off the flow of
+gasoline from the intake passage. As the throttle is opened the vacuum
+in the intake passage is broken, and the plunger falls, causing gasoline
+to gather above it. This is immediately drawn through the pick-up
+passage and gives the desired mixture for acceleration.
+
+
+MASTER MULTIPLE-JET CARBURETOR
+
+[Illustration: Fig. 49.--The Master Carburetor.]
+
+This carburetor, shown in detail in Figs. 49 and 50, has been very
+popular in racing cars and aviation engines because of exceptionally
+good pick-up qualities and its thorough atomization of fuel. Its
+principle of operation is the breaking up of the fuel by a series of
+jets, which vary in number from fourteen to twenty-one, according to
+the size of the carburetor. These are uncovered by opening the throttle,
+which is curved--a patented feature--to secure the correct progression
+of jets. The carburetor has an eccentric float chamber, from which the
+gasoline is led to the jet piece from which the jets stand up in a row.
+The tops of these jets are closed until the throttle is opened far
+enough to pass them, which it does progressively. The air opening is at
+the bottom, and the throttle opening is such that a modified venturi is
+formed. The throttle is carried in a cylindrical barrel with the jets
+placed below it, and the passage from the barrel to the intake is
+arranged so that there is no interruption in the flow. For easy starting
+a dash-controlled shutter closes off the air, throwing the suction on
+the jets, thus giving a rich mixture.
+
+[Illustration: Fig. 50.--Sectional View of Master Carburetor Showing
+Parts.]
+
+The only adjustment is for idling, and once that is fixed it need never
+be touched. This is in the form of a screw and regulates the position of
+the throttle when at idling position. The dash control has high-speed,
+normal and rich-starting positions. In installing the Master carburetor
+the float chamber may be turned either toward the radiator or driver's
+seat. If the float is turned toward the radiator, however, a forward lug
+plate should be ordered; otherwise it will be difficult to install the
+control. The throttle lever must go all the way to the stop lug or
+maximum power will not be secured. In adjusting the idle screw it is
+turned in for rich and out for lean.
+
+
+COMPOUND NOZZLE ZENITH CARBURETOR
+
+[Illustration: Fig. 51.--Sectional View of Zenith Compound Nozzle
+Compensating Carburetor.]
+
+The Zenith carburetor, shown at Fig. 51, has become very popular for
+airplane engine use because of its simplicity, as mixture compensation
+is secured by a compensating compound nozzle principle that works very
+well in practice. To illustrate this principle briefly, let us consider
+the elementary type of carburetor or mixing valve, as shown in Fig. 52,
+A. It consists of a single jet or spraying nozzle placed in the path of
+the incoming air and fed from the usual float chamber. It is a natural
+inference to suppose that as the speed of the motor increases, both the
+flow of air and of gasoline will increase in the same proportion.
+Unhappily, such is not the case. There is a law of liquid bodies which
+states that the flow of gasoline from the jet increases under suction
+faster than the flow of air, giving a mixture which grows richer and
+richer--a mixture containing a much higher percentage of gasoline at
+high suction than at low. The tendency is shown by the accompanying
+curve (Fig. 52, B), which gives the ratio of gasoline to air at varying
+speeds from this type of jet. The mixture is practically constant only
+between narrow limits and at very high speed. The most common method of
+correcting this defect is by putting various auxiliary air valves which,
+adding air, tends to dilute this mixture as it gets too rich. It is
+difficult with makeshift devices to gauge this dilution accurately for
+every motor speed.
+
+[Illustration: Fig. 52.--Diagrams Explaining Action of Baverey Compound
+Nozzle Used in Zenith Carburetor.]
+
+Now, if we have a jet which grows richer as the suction increases, the
+opposite type of jet is one which would grow leaner under similar
+conditions. Baverey, the inventor of the Zenith, discovered the
+principle of the constant flow device which is shown in Fig. 52, C. Here
+a certain fixed amount of gasoline determined by the opening I is
+permitted to flow by gravity into the well J open to the air. The
+suction at jet H has no effect upon the gravity compensator I because
+the suction is destroyed by the open well J. The compensator, then,
+delivers a steady rate of flow per unit of time, and as the motor
+suction increases more air is drawn up, while the amount of gasoline
+remains the same and the mixture grows poorer and poorer. Fig. 52, D,
+shows this curve.
+
+By combining these two types of rich and poor mixture carburetors the
+Zenith compound nozzle was evolved. In Fig. 52, E, we have both the
+direct suction or richer type leading through pipe E and nozzle G and
+the "constant flow" device of Baverey shown at J, I, K and nozzle H. One
+counteracts the defects of the other, so that from the cranking of the
+motor to its highest speed there is a constant ratio of air and
+gasoline to supply efficient combustion.
+
+In addition to the compound nozzle the Zenith is equipped with a
+starting and idling well, shown in the cut of Model L carburetor at P
+and J. This terminates in a priming hole at the edge of the butterfly
+valve, where the suction is greatest when this valve is slightly open.
+The gasoline is drawn up by the suction at the priming hole and, mixed
+with the air rushing by the butterfly, gives an ideal slow speed
+mixture. At higher speeds with the butterfly valve opened further the
+priming well ceases to operate and the compound nozzle drains the well
+and compensates correctly for any motor speed.
+
+[Illustration: Fig. 53.--The Zenith Duplex Carburetor for Airplane
+Motors of the V Type.]
+
+With the coming of the double motor containing eight or twelve cylinders
+arranged in two V blocks, the question of good carburetion has been a
+problem requiring much study. The single carburetor has given only
+indifferent results due to the strong cross suction in the inlet
+manifold from one set of cylinders to the other. This naturally led to
+the adoption of two carburetors in which each set of cylinders was
+independently fed by a separate carburetor. Results from this system
+were very good when the two carburetors were working exactly in unison,
+but as it was extremely difficult to accomplish this co-operation,
+especially where the adjustable type was employed, this system never
+gained in favor. The next logical step was the Zenith Duplex, shown at
+Fig. 53. This consists of two separate and distinct carburetors joined
+together so that a common gasoline float chamber and air inlet could be
+used by both. It does away with cross suction in the manifold because
+each set of cylinders has a separate intake of its own. It does away
+with two carburetors and makes for simplicity. The practical application
+of the Zenith carburetor to the Curtiss 90 horse-power OX-2 motor used
+on the JN-4 standard training machine is shown at Fig. 54, which
+outlines a rear view of the engine in question. The carburetor is
+carried low to permit of fuel supply from a gravity tank carried back of
+the motor.
+
+[Illustration: Fig. 54.--Rear View of Curtiss OX-2 90 Horse-Power
+Airplane Motor Showing Carburetor Location and Hot Air Leads.]
+
+
+UTILITY OF GASOLINE STRAINERS
+
+Many carburetors include a filtering screen at the point where the
+liquid enters the float chamber in order to keep dirt or any other
+foreign matter which may be present in the fuel from entering the float
+chamber. This is not general practice, however, and the majority of
+vaporizers do not include a filter in their construction. It is very
+desirable that the dirt should be kept out of the carburetor because it
+may get under the float control fuel valve and cause flooding by keeping
+it raised from its seat. If it finds its way into the spray nozzle it
+may block the opening so that no gasoline will issue or may so constrict
+the passage that only very small quantities of fuel will be supplied the
+mixture. Where the carburetor itself is not provided with a filtering
+screen a simple filter is usually installed in the pipe line between the
+gasoline tank and the float chamber.
+
+Some simple forms of filters and separators are shown at Fig. 55. That
+at A consists of a simple brass casting having a readily detachable
+gauze screen and a settling chamber of sufficient capacity to allow the
+foreign matter to settle to the bottom, from which it is drained out by
+a pet cock. Any water or dirt in the gasoline will settle to the bottom
+of the chamber, and as all fuel delivered to the carburetor must pass
+through the wire gauze screen it is not likely to contain impurities
+when it reaches the float chamber. The heavier particles, such as scale
+from the tank or dirt and even water, all of which have greater weight
+than the gasoline, will sink to the bottom of the chamber, whereas
+light particles, such as lint, will be prevented from flowing into the
+carburetor by the filtering screen.
+
+[Illustration: Fig. 55.--Types of Strainers Interposed Between Vaporizer
+and Gasoline Tank to Prevent Water or Dirt Passing Into Carbureting
+Device.]
+
+The filtering device shown at B is a larger appliance than that shown at
+A, and should be more efficient as a separator because the gasoline is
+forced to pass through three filtering screens before it reaches the
+carburetor. The gasoline enters the device shown at C through a bent
+pipe which leads directly to the settling chamber and from thence
+through a wire gauze screen to the upper compartment which leads to the
+carburetor. The device shown at D is a combination strainer, drain, and
+sediment cup. The filtering screen is held in place by a spring and
+both are removed by taking out a plug at the bottom of the device. The
+shut-off valve at the top of the device is interposed between the
+sediment cup and the carburetor. This separating device is incorporated
+with the gasoline tank and forms an integral part of the gasoline supply
+system. The other types shown are designed to be interposed between the
+gasoline tank and the carburetor at any point in the pipe line where
+they may be conveniently placed.
+
+
+INTAKE MANIFOLD DESIGN AND CONSTRUCTION
+
+On four- and six-cylinder engines and in fact on all multiple-cylinder
+forms, it is important that the piping leading from the carburetor to
+the cylinders be made in such a way that the various cylinders will
+receive their full quota of gas and that each cylinder will receive its
+charge at about the same point in the cycle of operations. In order to
+make the passages direct the bends should be as few as possible, and
+when curves are necessary they should be of large radius because an
+abrupt corner will not only impede gas flow but will tend to promote
+condensation of the fuel. Every precaution should be taken with
+four- and six-cylinder engines to insure equitable gas distribution to
+the valve chambers if regular action of the power plant is desired. If
+the gas pipe has many turns and angles it will be difficult to charge
+all cylinders properly. On some six-cylinder aviation engines, two
+carburetors are used because of trouble experienced with manifolds
+designed for one carburetor. Duplex carburetors are necessary to secure
+the best results from eight- and twelve-cylinder V engines.
+
+The problem of intake piping is simplified to some extent on block
+motors where the intake passage is cored in the cylinder casting and
+where but one short pipe is needed to join this passage to the
+carburetor. If the cylinders are cast in pairs a simple pipe of T or Y
+form can be used with success. When the engine is of a type using
+individual cylinder castings, especially in the six-cylinder power
+plants, the proper application and installation of suitable piping is a
+difficult problem. The reader is referred to the various engine designs
+outlined to ascertain how the inlet piping has been arranged on
+representative aviation engines. Intake piping is constructed in two
+ways, the most common method being to cast the manifold of brass or
+aluminum. The other method, which is more costly, is to use a built-up
+construction of copper or brass tubing with cast metal elbows and Y
+pieces. One of the disadvantages advanced against the cast manifold is
+that blowholes may exist which produce imperfect castings and which will
+cause mixture troubles because the entering gas from the carburetor,
+which may be of proper proportions, is diluted by the excess air which
+leaks in through the porous casting. Another factor of some moment is
+that the roughness of the walls has a certain amount of friction which
+tends to reduce the velocity of the gases, and when projecting pieces
+are present, such as core wire or other points of metal, these tend to
+collect the drops of liquid fuel and thus promote condensation. The
+advantage of the built-up construction is that the walls of the tubing
+are very smooth, and as the castings are small it is not difficult to
+clean them out thoroughly before they are incorporated in the manifold.
+The tubing and castings are joined together by hard soldering, brazing
+or autogenous welding.
+
+
+COMPENSATING FOR VARYING ATMOSPHERIC CONDITIONS
+
+The low-grade gasoline used at the present time makes it necessary to
+use vaporizers that are more susceptible to atmospheric variations than
+when higher grade and more volatile liquids are vaporized. Sudden
+temperature changes, sometimes being as much as forty degrees rise or
+fall in twelve hours, affect the mixture proportions to some extent, and
+not only changes in temperature but variations in altitude also have a
+bearing on mixture proportions by affecting both gasoline and air. As
+the temperature falls the specific gravity of the gasoline increases
+and it becomes heavier, this producing difficulty in vaporizing. The
+tendency of very cold air is to condense gasoline instead of vaporizing
+it and therefore it is necessary to supply heated air to some
+carburetors to obtain proper mixtures during cold weather. In order that
+the gas mixtures will ignite properly the fuel must be vaporized and
+thoroughly mixed with the entering air either by heat or high velocity
+of the gases. The application of air stoves to the Curtiss OX-2 motor is
+clearly shown at Fig. 54. It will be seen that flexible metal pipes are
+used to convey the heated air to the air intakes of the duplex mixing
+chamber.
+
+[Illustration: Fig. 56.--Chart Showing Diminution of Air Pressure as
+Altitude Increases.]
+
+
+HOW HIGH ALTITUDE AFFECTS POWER
+
+Any internal combustion engine will show less power at high altitudes
+than it will deliver at sea level, and this has caused a great deal of
+questioning. "There is a good reason for this," says a writer in "Motor
+Age," "and it is a physical impossibility for the engine to do
+otherwise. The difference is due to the lower atmospheric pressure the
+higher up we get. That is, at sea level the atmosphere has a pressure of
+14.7 pounds per square inch; at 5,000 feet above sea level the pressure
+is approximately 12.13 pounds per square inch, and at 10,000 feet it is
+10 pounds per square inch. From this it will be seen that the final
+pressure attained after the piston has driven the gas into compressed
+condition ready for firing is lower as the atmospheric pressure drops.
+This means that there is not so much power in the compressed charge of
+gas the higher up you get above sea level.
+
+"For example, suppose the compression ratio to be 4-1/2 to 1; in other
+words, suppose the air space above the piston to have 4-1/2 times the
+volume when the piston is at the bottom of its stroke that it has when
+the piston is at the top of the stroke. That is a common compression
+ratio for an average motor, and is chosen because it is considered to be
+the best for maximum horse-power and in order that the compression
+pressure will not be so high as to cause pre-ignition. Knowing the
+compression ratio, we can determine the final pressure immediately
+before ignition by substituting in the standard formula:
+
+  P^{1} = P(V/V^{1})^{1.3}
+
+in which P is the atmospheric pressure; P^{1} is the final pressure, and
+V/V^{1} is the compression ratio, therefore P^{1} = 14.7 (4.5)^{1.3} =
+104 pounds per square inch, absolute.
+
+"That is, 104 pounds per square inch is the most efficient final
+compression pressure to have for this engine at sea level, since it
+comes directly from the compression ratio.
+
+"Now supposing we consider that the altitude is 7,000 feet above sea
+level. At this height the atmospheric pressure is 11.25 pounds per
+square inch, approximately. In this case we can again substitute in the
+formula, using the new atmospheric pressure figure. The equation
+becomes:
+
+  P^{1} = 11.25 (4.5)^{1.3}--79.4 pounds per square inch, absolute.
+
+"Therefore we now have a final compression pressure of only 79.4 pounds
+per square inch, which is considerably below the pressure we have just
+found to be the most efficient for the motor. The resulting power drop
+is evident.
+
+"It should be borne in mind that these final compression pressures are
+absolute pressures--that is, they include the atmospheric pressure. In
+the first case, to get the pressure above atmospheric you would subtract
+14.7 and in the latter 11.25 would have to be deducted. In other words,
+where the sea level compression is 89.3 pounds per square inch above the
+atmosphere, the same motor will have only a compression pressure of
+68.15 pounds per square inch above the atmosphere at 7,000 feet
+elevation.
+
+"From the above it is evident that in order to bring the final
+compression pressure up to the efficient figure we have determined, a
+different compression ratio would have to be used. That is, the final
+volume would have to be less, and as it is impossible to vary this to
+meet the conditions of altitude, the loss of power cannot be helped
+except by the replacing of the standard pistons with some that are
+longer above the wrist-pin so as to reduce the space above the pistons
+when on top center. Then if the ratio is thereby raised to some such
+figures as 5 to 1, the engine will again have its proper final pressure,
+but it will still not have as much power as it would have at sea level,
+since the horse-power varies directly with the atmospheric pressure,
+final compression being kept constant. That is, at 7,000 feet the
+horse-power of an engine that had 40 horse-power at sea level would be
+equal to
+
+   11.25
+  ------- = 30.6 horse-power.
+   14.7
+
+"If the original compression ratio of 4.5 were retained, the drop in
+horse-power would be even greater than this. These computations and
+remarks will make it clear that the designer who contemplates building
+an airplane for high altitude use should see to it that it is of
+sufficient power to compensate for the drop that is inevitable when it
+is up in the air. This is often illustrated in stationary gas-engine
+installations. An engine that had a sea-level rating amply sufficient
+for the work required, might not be powerful enough when brought up
+several thousand feet." When one considers that airplanes attain heights
+of over 18,000 feet, it will be evident that an ample margin of engine
+power is necessary.
+
+
+THE DIESEL SYSTEM
+
+A system of fuel supply developed by the late Dr. Diesel, a German
+chemist and engineer, is attracting considerable attention at the
+present time on account of the ability of the Diesel engine to burn
+low-grade fuels, such as crude petroleum. In this system the engines are
+built so that very high compressions are used, and only pure air is
+taken into the cylinder on the induction stroke. This is compressed to a
+pressure of about 500 pounds per square inch, and sufficient heat is
+produced by this compression to explode a hydrocarbon mixture. As the
+air which is compressed to this high point cannot burn, the fuel is
+introduced into the cylinder combustion chamber under still higher
+compression than that of the compressed air, and as it is injected in a
+fine stream it is immediately vaporized because of the heat. Just as
+soon as the compressed air becomes thoroughly saturated with the liquid
+fuel, it will explode on account of the degree of heat present in the
+combustion chamber. Such motors have been used in marine and stationary
+applications, but are not practical for airplanes or motor cars because
+of lack of flexibility and great weight in proportion to power
+developed. The Diesel engine is the standard power plant used in
+submarine boats and motor ships, as its efficiency renders it
+particularly well adapted for large units.
+
+
+NOTES ON CARBURETOR INSTALLATION IN AIRPLANES
+
+A writer in "The Aeroplane," an English publication, discourses on some
+features of carburetor installation that may be of interest to the
+aviation student, so portions of the dissertation are reproduced
+herewith.
+
+    "Users of airplanes fitted with ordinary type carburetors will
+    do well to note carefully the way in which these are fitted, for
+    several costly machines have been burnt lately through the sheer
+    carelessness of their users. These particular machines were
+    fitted with a high powered V-type engine, made by a firm which
+    is famous as manufacturers of automobiles _de luxe_. In these
+    engines there are four carburetors, mounted in the V between the
+    cylinders. When the engine is fitted as a tractor, the float
+    chambers are in front of the jet chambers. Consequently, when
+    the tail of the machine is resting on the ground, the jets are
+    lower than the level of the gasoline in the float chamber.
+
+    "Quite naturally, the gasoline runs out of the jet, if it is
+    left turned on when the machine is standing in its normal
+    position, and trickles into the V at the top of the crank-case.
+    Thence it runs down to the tail of the engine, where the
+    magnetos are fitted, and saturates them. If left long enough,
+    the gasoline manages to soak well into the fuselage before
+    evaporating. And what does evaporate makes an inflammable gas in
+    the forward cockpit. Then some one comes along and starts up the
+    engine. The spark-gap of the magneto gives one flash, and the
+    whole front of the machine proceeds to give a Fourth of July
+    performance forthwith. Naturally, one safeguard is to turn the
+    petrol off directly the machine lands. Another is never to turn
+    it on till the engine is actually being started up.
+
+    "One would be asking too much of the human boy--who is
+    officially regarded as the only person fit to fly an
+    aeroplane--if one depended upon his memory of such a detail to
+    save his machine, though one might perhaps reasonably expect the
+    older pilots to remember not to forget. Even so, other means of
+    prevention are preferable, for fire is quite as likely to occur
+    from just the same cause if the engine happens to be a trifle
+    obstinate in starting, and so gives the carburetors several
+    minutes in which to drip--in which operation they would probably
+    be assisted by air-mechanics 'tickling' them.
+
+    "One way out of the trouble is to fit drip tins under the jet
+    chamber to catch the gasoline as it falls. This is all very well
+    just to prevent fire while the machine is being started up, but
+    it will not save it if it is left standing with the tail on the
+    ground and the petrol turned on, for the drip tins will then
+    fill up and run over. And if it catches then, the contents of
+    the drip tins merely add fuel to the fire.
+
+
+    _Reversing Carburetors_
+
+    "Yet another way is to turn the carburetors round, so that the
+    float chambers are behind the jets, and so come below them when
+    the tail is on the ground, thus cutting off the gasoline low
+    down in the jets. There seems to be no particular mechanical
+    difficulty about this, though I must confess that I did not note
+    very carefully whether the reversal of the float chambers would
+    make them foul any other fittings on the engine. It has been
+    argued, however, that doing this would starve the engine of
+    gasoline when climbing at a steep angle, as the gasoline would
+    then be lowered in the jets and need more suction to get into
+    the cylinders. This is rather a pretty point of amateur motor
+    mechanics to discuss, for, obviously, when the same engine is
+    used as a 'pusher' instead of a tractor, the jets are in front
+    of the floats, and there seems to be no falling off in power.
+
+
+    _Starvation of Mixture_
+
+    "Moreover, the higher a machine goes the lower is the
+    atmospheric pressure, and, consequently, the less is the amount
+    of air sucked in at each induction stroke. This means, of
+    course, that with the gasoline supply the mixture at high
+    altitudes is too rich, so that, in order to get precisely the
+    right mixture when very high up, it is necessary to reduce the
+    gasoline supply by screwing down the needle valve between the
+    tank and the carburetor--at least, that has been the experience
+    of various high-flying pilots. No doubt something might be done
+    in the way of forced air feed to compensate for reduced
+    atmospheric pressure, but it remains to be proved whether the
+    extra weight of mechanism involved would pay for the extra power
+    obtained. Variable compression might do something, also, to even
+    things up, but here, also, weight of mechanism has to be
+    considered.
+
+    "In any case, at present, the higher one goes the more the
+    power of the engine is reduced, for less air means a less volume
+    of mixture per cylinder, and as the petrol feed has to be
+    starved to suit the smaller amount of air available, this means
+    further loss of power. I do not know whether anyone has evolved
+    a carburetor which automatically starves the gasoline feed when
+    high up, but it seems possible that when an airplane is sagging
+    about 'up against the ceiling'--as a French pilot described the
+    absolute limit of climb for his particular machine--it might be
+    a good thing to have the jets in front of the float chamber, for
+    then a certain amount of automatic starvation would take place.
+
+    "When a machine is right up at its limiting height, and the
+    pilot is doing his best to make it go higher still, it is
+    probably flying with its tail as low as the pilot dares to let
+    it go, and the lateral and longitudinal controls are on the
+    verge of vanishing, so that if the carburetor jets are behind
+    the float chambers there is bound to be an over-rich mixture in
+    any case. There is even a possibility of a careless or ignorant
+    pilot carrying on in this tail-down position till one set of
+    cylinders cuts out altogether, in which case the carburetor
+    feeding that set may flood over, just as if the machine were on
+    the ground, and the whole thing may catch fire. Whereas, with
+    the jets in front of the floats, though the mixture may starve a
+    trifle, there is, at any rate, no danger of fire through
+    climbing with the tail down.
+
+
+    _A Diving Danger_
+
+    "On the other hand, in a 'pusher' with this type of engine, if
+    the jets are in their normal position--which is in front of the
+    floats--there is danger of fire in a dive. That is to say, if
+    the pilot throttles right down, or switches off and relies on
+    air pressure on his propeller to start the engine again, so that
+    the gasoline is flooding over out of the jets instead of being
+    sucked into the engine, there may be flooding over the magnetos
+    if the dive is very steep and prolonged. In any case, a long
+    dive will mean a certain amount of flooding, and, probably, a
+    good deal of choking and spitting by the engine before it gets
+    rid of the over-rich mixture and picks up steady firing again.
+    Which may indicate to young pilots that it is not good to come
+    down too low under such circumstances, trusting entirely to
+    their engines to pick up at once and get going before they hit
+    the ground.
+
+    "On the whole, it seems that it might be better practice to set
+    the carburetors thwartwise of engines, for then jets and floats
+    would always be at approximately the same level, no matter what
+    the longitudinal position of the machine, and it is never long
+    enough in one position at a big lateral angle to raise any
+    serious carburetor troubles. Car manufacturers who dive
+    cheerfully into the troubled waters of aero-engine designs are
+    a trifle apt to forget that their engines are put into positions
+    on airplanes which would be positively indecent in a motor car.
+    An angle of 1 in 10 is the exception on a car, but it is common
+    on an airplane, and no one ever heard of a car going down a hill
+    of 10 to 1--which is not quite a vertical dive. Therefore, there
+    is every excuse for a well-designed and properly brought-up
+    carburetor misbehaving itself in an aeroplane.
+
+    "It seems, then, that it is up to the manufacturers to produce
+    better carburetors--say, with the jet central with the float.
+    But it also behooves the user to show ordinary common sense in
+    handling the material at present available, and not to make a
+    practice of burning up $25,000 worth or so of airplane just
+    because he is too lazy to turn off his gasoline, or to have the
+    tail of his machine lifted up while he is tinkering with his
+    engines."
+
+
+NOTES ON CARBURETOR ADJUSTMENT
+
+The modern float feed carburetor is a delicate and nicely balanced
+appliance that requires a certain amount of attention and care in order
+to obtain the best results. The adjustments can only be made by one
+possessing an intelligent knowledge of carburetor construction and must
+never be made unless the reason for changing the old adjustment is
+understood. Before altering the adjustment of the leading forms of
+carburetors, a few hints regarding the quality to be obtained in the
+mixture should be given some consideration, as if these are properly
+understood this knowledge will prove of great assistance in adjusting
+the vaporizer to give a good working proportion of fuel and air. There
+is some question regarding the best mixture proportions and it is
+estimated that gas will be explosive in which the proportions of fuel
+vapor and air will vary from one part of the former to a wide range
+included between four and eighteen parts of the latter. A one to four
+mixture is much too rich, while the one in eighteen is much too lean to
+provide positive ignition.
+
+A rich mixture should be avoided because the excessive fuel used will
+deposit carbon and will soot the cylinder walls, combustion chamber
+interior, piston top and valves and also tend to overheat the motor. A
+rich mixture will also seriously interfere with flexible control of the
+engine, as it will choke up on low throttle and run well on open
+throttle when the full amount of gas is needed. A rich mixture may be
+quickly discovered by black smoke issuing from the muffler, the exhaust
+gas having a very pungent odor. If the mixture contains a surplus of air
+there will be popping sounds in the carburetor, which is commonly termed
+"blowing back." To adjust a carburetor is not a difficult matter when
+the purpose of the various control members is understood. The first
+thing to do in adjusting a carburetor is to start the motor and to
+retard the sparking lever so the motor will run slowly leaving the
+throttle about half open. In order to ascertain if the mixture is too
+rich cut down the gasoline flow gradually by screwing down the needle
+valve until the motor commences to run irregularly or misfire. Close the
+needle valves as far as possible without having the engine come to a
+stop, and after having found the minimum amount of fuel gradually
+unscrew the adjusting valve until you arrive at the point where the
+engine develops its highest speed. When this adjustment is secured the
+lock nut is screwed in place so the needle valve will keep the
+adjustment. The next point to look out for is regulation of the
+auxiliary air supply on those types of carburetors where an adjustable
+air valve is provided. This is done by advancing the spark lever and
+opening the throttle. The air valve is first opened or the spring
+tension reduced to a point where the engine misfires or pops back in the
+carburetor. When the point of maximum air supply the engine will run on
+is thus determined, the air valve spring may be tightened by screwing in
+on the regulating screw until the point is reached where an appreciable
+speeding up of the engine is noticed. If both fuel and air valves are
+set right, it will be possible to accelerate the engine speed uniformly
+without interfering with regularity of engine operation by moving the
+throttle lever or accelerator pedal from its closed to its wide open
+position, this being done with the spark lever advanced. All types of
+carburetors do not have the same means of adjustment; in fact, some
+adjust only with the gasoline regulating needle; others must have a
+complete change of spray nozzles; while in others the mixture
+proportions may be varied only by adjustment of the quantity of entering
+air. Changing the float level is effective in some carburetors, but this
+should never be done unless it is certain that the level is not correct.
+Full instructions for locating carburetion troubles will be given in
+proper sequence.
+
+It is a fact well known to experienced repairmen and motorists that
+atmospheric conditions have much to do with carburetor action. It is
+often observed that a motor seems to develop more power at night than
+during the day, a circumstance which is attributed to the presence of
+more moisture in the cooler night air. Likewise, taking a motor from sea
+level to an altitude of 10,000 feet involves using rarefied air in the
+engine cylinders and atmospheric pressures ranging from 14.7 pounds at
+sea level to 10.1 pounds per square inch at the high altitude. All
+carburetors will require some adjustment in the course of any material
+change from one level to another. Great changes of altitude also have a
+marked effect on the cooling system of an airplane. Water boils at 212
+degrees F. only at sea level. At an altitude of 10,000 feet it will boil
+at a temperature nineteen degrees lower, or 193 degrees F.
+
+In high altitudes the reduced atmospheric pressure, for 5,000 feet or
+higher than sea level, results in not enough air reaching the mixture,
+so that either the auxiliary air opening has to be increased, or the
+gasoline in the mixture cut down. If the user is to be continually at
+high altitudes he should immediately purchase either a larger dome or a
+smaller strangling tube, mentioning the size carburetor that is at
+present in use and the type of motor that it is on, including details as
+to the bore and stroke. The smaller strangling tube makes an increased
+suction at the spray nozzle; the air will have to be readjusted to meet
+it and you can use more auxiliary air, which is necessary. The effect
+on the motor without a smaller strangling tube is a perceptible
+sluggishness and failure to speed up to its normal crank-shaft
+revolutions, as well as failure to give power. It means that about
+one-third of the regular speed is cut out. The reduced atmospheric
+pressure reduces the power of the explosion, in that there is not the
+same quantity of oxygen in the combustion chamber as at sea level; to
+increase the amount taken in, you must also increase the gasoline speed,
+which is done by an increased suction through the smaller strangling
+aperture. Some forms of carburetors are affected more than others by
+changes of altitude, which explains why the Zenith is so widely employed
+for airplane engine use. The compensating nozzle construction is not
+influenced as much by changes of altitude as the simpler nozzle types
+are.
+
+
+
+
+CHAPTER VI
+
+    Early Ignition Systems--Electrical Ignition Best--Fundamentals
+    of Magnetism Outlined--Forms of Magneto--Zones of Magnetic
+    Influence--How Magnets are Made--Electricity and Magnetism
+    Related--Basic Principles of Magneto Action--Essential Parts of
+    Magneto and Functions--Transformer Coil Systems--True High
+    Tension Type--The Berling Magneto--Timing and Care--The Dixie
+    Magneto--Spark Plug Design and Application--Two-Spark Ignition--
+    Special Airplane Plug.
+
+
+EARLY IGNITION SYSTEMS
+
+One of the most important auxiliary groups of the gasoline engine
+comprising the airplane power plant and one absolutely necessary to
+insure engine action is the ignition system or the method employed of
+kindling the compressed gas in the cylinder to produce an explosion and
+useful power. The ignition system has been fully as well developed as
+other parts of the engine, and at the present time practically all
+ignition systems follow principles which have become standard through
+wide acceptance.
+
+During the early stages of development of the gasoline engine various
+methods of exploding the charge of combustible gas in the cylinder were
+employed. On some of the earliest engines a flame burned close to the
+cylinder head, and at the proper time for ignition a slide or valve
+moved to provide an opening which permitted the flame to ignite the gas
+back of the piston. This system was practical only on the primitive form
+of gas engines in which the charge was not compressed before ignition.
+Later, when it was found desirable to compress the gas a certain degree
+before exploding it, an incandescent platinum tube in the combustion
+chamber, which was kept in a heated condition by a flame burning in it,
+exploded the gas. The naked flame was not suitable in this application
+because when the slide was opened to provide communication between the
+flame and the gas the compressed charge escaped from the cylinder with
+enough pressure to blow out the flame at times and thus cause irregular
+ignition. When the flame was housed in a platinum tube it was protected
+from the direct action of the gas, and as long as the tube was
+maintained at the proper point of incandescence regular ignition was
+obtained.
+
+Some engineers utilized the property of gases firing themselves if
+compressed to a sufficient degree, while others depended upon the heat
+stored in the cylinder-head to fire the highly compressed gas. None of
+these methods were practical in their application to motor car engines
+because they did not permit flexible engine action which is so
+desirable. At the present time, electrical ignition systems in which the
+compressed gas is exploded by the heating value of the minute electric
+arc or spark in the cylinder are standard, and the general practice
+seems to be toward the use of mechanical producers of electricity rather
+than chemical batteries.
+
+
+ELECTRICAL IGNITION BEST
+
+Two general forms of electrical ignition systems may be used, the most
+popular being that in which a current of electricity under high tension
+is made to leap a gap or air space between the points of the sparking
+plug screwed into the cylinder. The other form, which has been almost
+entirely abandoned in automobile and which was never used with airplane
+engine practice, but which is still used to some extent on marine
+engines, is called the low-tension system because current of low voltage
+is used and the spark is produced by moving electrodes in the combustion
+chamber.
+
+The essential elements of any electrical ignition system, either high or
+low tension, are: First, a simple and practical method of current
+production; second, suitable timing apparatus to cause the spark to
+occur at the right point in the cycle of engine action; third, suitable
+wiring and other apparatus to convey the current produced by the
+generator to the sparking member in the cylinder.
+
+The various appliances necessary to secure prompt ignition of the
+compressed gases should be described in some detail because of the
+importance of the ignition system. It is patent that the scope of a work
+of this character does not permit one to go fully into the theory and
+principles of operation of all appliances which may be used in
+connection with gasoline motor ignition, but at the same time it is
+important that the elementary principles be considered to some extent in
+order that the reader should have a proper understanding of the very
+essential ignition apparatus. The first point considered will be the
+common methods of generating the electricity, then the appliances to
+utilize it and produce the required spark in the cylinder. Inasmuch as
+magneto ignition is universally used in connection with airplane engine
+ignition it will not be necessary to consider battery ignition systems.
+
+
+FUNDAMENTALS OF MAGNETISM OUTLINED
+
+To properly understand the phenomena and forces involved in the
+generation of electrical energy by mechanical means it is necessary to
+become familiar with some of the elementary principles of magnetism and
+its relation to electricity. The following matter can be read with
+profit by those who are not familiar with the subject. Most persons know
+that magnetism exists in certain substances, but many are not able to
+grasp the terms used in describing the operation of various electrical
+devices because of not possessing a knowledge of the basic facts upon
+which the action of such apparatus is based.
+
+Magnetism is a property possessed by certain substances and is
+manifested by the ability to attract and repel other materials
+susceptible to its effects. When this phenomenon is manifested by a
+conductor or wire through which a current of electricity is flowing it
+is termed "electro-magnetism." Magnetism and electricity are closely
+related, each being capable of producing the other. Practically all of
+the phenomena manifested by materials which possess magnetic qualities
+naturally can be easily reproduced by passing a current of electricity
+through a body which, when not under electrical influence, is not a
+magnetic substance. Only certain substances show magnetic properties,
+these being iron, nickel, cobalt and their alloys.
+
+The earliest known substance possessing magnetic properties was a stone
+first found in Asia Minor. It was called the lodestone or leading stone,
+because of its tendency, if arranged so it could be moved freely, of
+pointing one particular portion toward the north. The compass of the
+ancient Chinese mariners was a piece of this material, now known to be
+iron ore, suspended by a light thread or floated on a cork in some
+liquid so one end would point toward the north magnetic pole of the
+earth. The reason that this stone was magnetic was hard to define for a
+time, until it was learned that the earth was one huge magnet and that
+the iron ore, being particularly susceptible, absorbed and retained some
+of this magnetism.
+
+Most of us are familiar with some of the properties of the magnet
+because of the extensive sale and use of small horseshoe magnets as
+toys. As they only cost a few pennies every one has owned one at some
+time or other and has experimented with various materials to see if they
+would be attracted. Small pieces of iron or steel were quickly attracted
+to the magnet and adhered to the pole pieces when brought within the
+zone of magnetic influence. It was soon learned that brass, copper, tin
+or zinc were not affected by the magnet. A simple experiment that serves
+to illustrate magnetic attraction of several substances is shown at A,
+Fig. 57. In this, several balls are hung from a standard or support, one
+of these being of iron, another of steel. When a magnet is brought near
+either of these they will be attracted toward it, while the others will
+remain indifferent to the magnetic force. Experimenters soon learned
+that of the common metals only iron or steel were magnetic.
+
+[Illustration: Fig. 57.--Some Simple Experiments to Demonstrate Various
+Magnetic Phenomena and Clearly Outline Effects of Magnetism and Various
+Forms of Magnets.]
+
+If the ordinary bar or horseshoe magnet be carefully examined, one end
+will be found to be marked N. This indicates the north pole, while the
+other end is not usually marked and is the south pole. If the north pole
+of one magnet is brought near the south pole of another, a strong
+attraction will exist between them, this depending upon the size of the
+magnets used and the air gap separating the poles. If the south pole of
+one magnet is brought close to the end of the same polarity of the other
+there will be a pronounced repulsion of like force. These facts are
+easily proved by the simple experiment outlined at B, Fig. 57. A magnet
+will only attract or influence a substance having similar qualities. The
+like poles of magnets will repel each other because of the obvious
+impossibility of uniting two influences or forces of practically equal
+strength but flowing in opposite directions. The unlike poles of magnets
+attract each other because the force is flowing in the same direction.
+The flow of magnetism is through the magnet from south to north and the
+circuit is completed by the flow of magnetic influence through the air
+gap or metal armature bridging it from the north to the south pole.
+
+
+FORMS OF MAGNETS AND ZONE OF MAGNETIC INFLUENCE DEFINED
+
+Magnets are commonly made in two forms, either in the shape of a bar or
+horseshoe. These two forms are made in two types, simple or compound.
+The latter are composed of a number of magnets of the same form united
+so the ends of like polarity are laced together, and such a construction
+will be more efficient and have more strength than a simple magnet of
+the same weight. The two common forms of simple and compound magnets are
+shown at C, Fig. 57. The zone in which a magnetic influence occurs is
+called the magnetic field, and this force can be graphically shown by
+means of imaginary lines, which are termed "lines of force." As will be
+seen from the diagram at D, Fig. 57, the lines show the direction of
+action of the magnetic force and also show its strength, as they are
+closer together and more numerous when the intensity of the magnetic
+field is at its maximum. A simple method of demonstrating the presence
+of the force is to lay a piece of thin paper over the pole pieces of
+either a bar or horseshoe magnet and sprinkle fine iron filings on it.
+The particles of metal arrange themselves in very much the manner shown
+in the illustrations and prove that the magnetic field actually exists.
+
+The form of magnet used will materially affect the size and area of the
+magnetic field. It will be noted that the field will be concentrated to
+a greater extent with the horseshoe form because of the proximity of the
+poles. It should be understood that these lines have no actual
+existence, but are imaginary and assumed to exist only to show the way
+the magnetic field is distributed. The magnetic influence is always
+greater at the poles than at the center, and that is why a horseshoe or
+U-form magnet is used in practically all magnetos or dynamos. This
+greater attraction at the poles can be clearly demonstrated by
+sprinkling iron filings on bar and U magnets, as outlined at E, Fig. 57.
+A large mass gathers at the pole pieces, gradually tapering down toward
+the point where the attraction is least.
+
+From the diagrams it will be seen that the flow of magnetism is from one
+pole to the other by means of curved paths between them. This circuit is
+completed by the magnetism flowing from one pole to the other through
+the magnet, and as this flow is continued as long as the body remains
+magnetic it constitutes a magnetic circuit. If this flow were
+temporarily interrupted by means of a conductor of electricity moving
+through the field there would be a current of electricity induced in the
+conductor every time it cut the lines of force. There are three kinds of
+magnetic circuits. A non-magnetic circuit is one in which the magnetic
+influence completes its circuit through some substance not susceptible
+to the force. A closed magnetic circuit is one in which the influence
+completes its circuit through some magnetic material which bridges the
+gap between the poles. A compound circuit is that in which the magnetic
+influence passes through magnetic substances and non-magnetic substances
+in order to complete its circuit.
+
+
+HOW IRON AND STEEL BARS ARE MADE MAGNETIC
+
+Magnetism may be produced in two ways, by contact or induction. If a
+piece of steel is rubbed on a magnet it will be found a magnet when
+removed, having a north and south pole and all of the properties found
+in the energizing magnet. This is magnetizing by contact. A piece of
+steel will retain the magnetism imparted to it for a considerable length
+of time, and the influence that remains is known as residual magnetism.
+This property may be increased by alloying the steel with tungsten and
+hardening it before it is magnetized. Any material that will retain its
+magnetic influence after removal from the source of magnetism is known
+as a permanent magnet. If a piece of iron or steel is brought into the
+magnetic field of a powerful magnet it becomes a magnet without actual
+contact with the energizer. This is magnetizing by magnetic induction.
+If a powerful electric current flows through an insulated conductor
+wound around a piece of iron or steel it will make a magnet of it. This
+is magnetizing by electro-magnetic induction. A magnet made in this
+manner is termed an electro-magnet and usually the metal is of such a
+nature that it will not retain its magnetism when the current ceases to
+flow around it. Steel is used in all cases where permanent magnets are
+required, while soft iron is employed in all cases where an intermittent
+magnetic action is desired. Magneto field magnets are always made of
+tungsten steel alloy, so treated that it will retain its magnetism for
+lengthy periods.
+
+
+ELECTRICITY AND MAGNETISM CLOSELY RELATED
+
+There are many points in which magnetism and electricity are alike. For
+instance, air is a medium that offers considerable resistance to the
+passage of both magnetic influence and electric energy, although it
+offers more resistance to the passage of the latter. Minerals like iron
+or steel are very easily influenced by magnetism and easily penetrated
+by it. When one of these is present in the magnetic circuit the
+magnetism will flow through the metal. Any metal is a good conductor for
+the passage of the electric current, but few metals are good conductors
+of magnetic energy. A body of the proper metal will become a magnet due
+to induction if placed in the magnetic field, having a south pole where
+the lines of force enter it and a north pole where they pass out.
+
+We have seen that a magnet is constantly surrounded by a magnetic field
+and that an electrical conductor when carrying a current is also
+surrounded by a field of magnetic influence. Now if the conductor
+carrying a current of electricity will induce magnetism in a bar of iron
+or steel, by a reversal of this process, a magnetized iron or steel bar
+will produce a current of electricity in a conductor. It is upon this
+principle that the modern dynamo or magneto is constructed. If an
+electro-motive force is induced in a conductor by moving it across a
+field of magnetic influence, or by passing a magnetic field near a
+conductor, electricity is said to be generated by magneto-electric
+induction. All mechanical generators of the electric current using
+permanent steel magnets to produce a field of magnetic influence are of
+this type.
+
+
+BASIC PRINCIPLES OF MAGNETO OUTLINED
+
+The accompanying diagram, Fig. 58, will show these principles very
+clearly. As stated on an earlier page, if the lines of force in the
+magnetic field are cut by a suitable conductor an electrical impulse
+will be produced in that conductor. In this simple machine the lines of
+force exist between the poles of a horseshoe magnet. The conductor,
+which in this case is a loop of copper wire, is mounted upon a spindle
+in order that it may be rotated in the magnetic field to cut the lines
+of magnetic influence present between the pole pieces. Both of the ends
+of this loop are connected, one with the insulated drum shown upon the
+shaft, the other to the shaft. Two metal brushes are employed to collect
+the current and cause it to flow through the external circuit. It can
+be seen that when the shaft is turned in the direction of the arrow the
+loop will cut through the lines of magnetic influence and a current will
+be generated therein.
+
+[Illustration: Fig. 58.--Elementary Form of Magneto Showing Principal
+Parts Simplified to Make Method of Current Generation Clear.]
+
+The pressure of the current and the amount produced vary in accordance
+to the rapidity with which the lines of magnetic influence are cut. The
+armature of a practical magneto, therefore, differs materially from that
+shown in the diagram. A large number of loops of wire would be mounted
+upon this shaft in order that the lines of magnetic influence would be
+cut a greater number of times in a given period and a core of iron used
+as a backing for the wire. This would give a more rapid alternating
+current and a higher electro-motive force than would be the case with a
+smaller number of loops of wire.
+
+[Illustration: Fig. 59.--Showing How Strength of Magnetic Influence and
+of the Currents Induced in the Windings of Armature Vary with the
+Rapidity of Changes of Flow.]
+
+The illustrations at Fig. 59 show a conventional double winding
+armature and field magnetic of a practical magneto in part section and
+will serve to more fully emphasize the points previously made. If the
+armature or spindle were removed from between the pole pieces there
+would exist a field of magnetic influence as shown at Fig. 57, but the
+introduction of this component provides a conductor (the iron core) for
+the magnetic energy, regardless of its position, though the facility
+with which the influence will be transmitted depends entirely upon the
+position of the core. As shown at A, the magnetic flow is through the
+main body in a straight line, while at B, which position the armature
+has attained after one-eighth revolution, or 45 degrees travel in the
+direction of the arrow, the magnetism must pass through in the manner
+indicated. At C, which position is attained every half revolution, the
+magnetic energy abandons the longer path through the body of the core
+for the shorter passage offered by the side pieces, and the field thrown
+out by the cross bar disappears. On further rotation of the armature, as
+at D, the body of the core again becomes energized as the magnetic
+influence resumes its flow through it. These changes in the strength of
+the magnetic field when distorted by the armature core, as well as the
+intensity of the energy existing in the field, affect the windings, and
+the electrical energy induced therein corresponds in strength to the
+rapidity with which these changes in magnetic flow occur. The most
+pronounced changes in the strength of the field will occur as the
+armature passes from position B to D, because the magnetic field
+existing around the core will be destroyed and again re-established.
+
+During the most of the armature rotation the changes in strength will be
+slight and the currents induced in the wire correspondingly small; but
+at the instant the core becomes remagnetized, as the armature leaves
+position C, the current produced will be at its maximum, and it is
+necessary to so time the rotation of the armature that at this instant
+one of the cylinders is in condition to be fired. It is imperative that
+the armature be driven in such relation to the crank-shaft that each
+production of maximum current coincides with the ignition point, this
+condition existing twice during each revolution of the armature, or at
+every 180 degrees travel. Each position shown corresponds to 45 degrees
+travel of the armature, or one-eighth of a turn, and it takes just
+three-eighths revolution to change the position from A to that shown at
+D.
+
+
+ESSENTIAL PARTS OF A MAGNETO AND THEIR FUNCTIONS
+
+The magnets which produce the influence that in turn induces the
+electrical energy in the winding or loops of wire on the armature, and
+which may have any even number of opposed poles, are called field
+magnets. The loops of wire which are mounted upon a suitable drum and
+rotate in the field of magnetic influence in order to cut the lines of
+force is called an armature winding, while the core is the metal
+portion. The entire assembly is called the armature. The exposed ends of
+the magnets are called pole pieces and the arrangement used to collect
+the current is either a commutator or a collector. The stationary pieces
+which bear against the collector or commutator and act as terminals for
+the outside circuit are called brushes. These brushes are often of
+copper, or some of its alloys, because copper has a greater electrical
+conductivity than any other metal.
+
+These brushes are nearly always of carbon, which is sometimes
+electroplated with copper to increase its electrical conductivity,
+though cylinders of copper wire gauze impregnated with graphite are
+utilized at times. Carbon is used because it is not so liable to cut the
+metal of the commutator as might be the case if the contact was of the
+metal to metal type. The reason for this is that carbon has the peculiar
+property in that it materially assists in the lubrication of the
+commutator, and being of soft, unctuous composition, will wear and
+conform to any irregularities on the surface of the metal collector
+rings.
+
+The magneto in common use consists of a number of horseshoe magnets
+which are compound in form and attached to suitable cast-iron pole
+pieces used to collect and concentrate the magnetic influence of the
+various magnets. Between these pole pieces an armature rotates. This is
+usually shaped like a shuttle, around which are wound coils of insulated
+wire. These are composed of a large number of turns and the current
+produced depends in great measure upon the size of the wire and the
+number of turns per coil. An armature winding of large wire will deliver
+a current of great amperage, but of small voltage. An armature wound
+with very fine wire will deliver a current of high voltage but of low
+amperage. In the ordinary form of magneto, such as used for ignition,
+the current is alternating in character and the break in the circuit
+should be timed to occur when the armature is at the point of its
+greatest potential or pressure. Where such a generator is designed for
+direct current production the ends of the winding are attached to the
+segments of a commutator, but where the instrument is designed to
+deliver an alternating current one end of the winding is fastened to an
+insulator ring on one end of the armature shaft and the other end is
+grounded on the frame of the machine.
+
+The quantity of the current depends upon the strength of the magnetic
+field and the number of lines of magnetic influence acting through the
+armature. The electro-motive force varies as to the length of the
+armature winding and the number of revolutions at which the armature is
+rotated.
+
+
+THE TRANSFORMER SYSTEM USES LOW VOLTAGE MAGNETO
+
+The magneto in the various systems which employ a transformer coil is
+very similar to a low-tension generator in general construction, and the
+current delivered at the terminals seldom exceeds 100 volts. As it
+requires many times that potential or pressure to leap the gap which
+exists between the points of the conventional spark plug, a separate
+coil is placed in circuit to intensify the current to one of greater
+capacity. The essential parts of such a system and their relation to
+each other are shown in diagrammatic form at Fig. 60 and as a complete
+system at Fig. 61. As is true of other systems the magnetic influence is
+produced by permanent steel magnets clamped to the cast-iron pole pieces
+between which the armature rotates. At the point of greatest potential
+in the armature winding the current is broken by the contact breaker,
+which is actuated by a cam, and a current of higher value is induced in
+the secondary winding of the transformer coil when the low voltage
+current is passed through the primary winding.
+
+[Illustration: Fig. 60.--Diagrams Explaining Action of Low Tension
+Transformer Coil and True High Tension Magneto Ignition Systems.]
+
+[Illustration: Fig. 60A.--Side Sectional View of Bosch High-Tension
+Magneto Shows Disposition of Parts. End Elevation Depicts Arrangement of
+Interruptor and Distributor Mechanism.]
+
+It will be noted that the points of the contact breaker are together
+except for the brief instant when separated by the action of the point
+of the cam upon the lever. It is obvious that the armature winding is
+short-circuited upon itself except when the contact points are
+separated. While the armature winding is thus short-circuited there will
+be practically no generation of current. When the points are separated
+there is a sudden flow of current through the primary winding of the
+transformer coil, inducing a secondary current in the other winding,
+which can be varied in strength by certain considerations in the
+preliminary design of the apparatus. This current of higher potential or
+voltage is conducted directly to the plug if the device is fitted to a
+single-cylinder engine, or to the distributor arm if fitted to a
+multiple-cylinder motor. The distributor consists of an insulator in
+which is placed a number of segments, one for each cylinder to be fired,
+and so spaced that the number of degrees between them correspond to the
+ignition points of the motor. A two-cylinder motor would have two
+segments, a three-cylinder, three segments, and so on within the
+capacity of the instrument. In the illustration a four-cylinder
+distributor is fitted, and the distributing arm is in contact with the
+segment corresponding to the cylinder about to be fired.
+
+[Illustration: Fig. 61.--Berling Two-Spark Dual Ignition System.]
+
+
+TRUE HIGH-TENSION MAGNETOS ARE SELF-CONTAINED
+
+[Illustration: Fig. 62.--Berling Double-Spark Independent System.]
+
+The true high-tension magneto differs from the preceding inasmuch as the
+current of high voltage is produced in the armature winding direct,
+without the use of the separate coil. Instead of but one coil, the
+armature carries two, one of comparatively coarse wire, the other of
+many turns of finer wire. The arrangement of these windings can be
+readily ascertained by reference to the diagram B, Fig. 60, which shows
+the principle of operation very clearly. The simplicity of the ignition
+system is evident by inspection of Fig. 62. One end of the primary
+winding (coarse wire) is coupled or grounded to the armature core, and
+the other passes to the insulated part of the interrupter. While in some
+forms the interrupter or contact breaker mechanism does not revolve, the
+desired motion being imparted to the contact lever to separate the
+points of a revolving cam, in this the cam or tripping mechanism is
+stationary and the contact breaker revolves. This arrangement makes it
+possible to conduct the current from the revolving primary coil to the
+interrupter by a direct connection, eliminating the use of brushes,
+which would otherwise be necessary. In other forms of this appliance
+where the winding is stationary, the interrupter may be operated by a
+revolving cam, though, if desired, the used of a brush at this point
+will permit this construction with a revolving winding.
+
+During the revolution of the armature the grounded lever makes and
+breaks contact with the insulated point, short-circuiting the primary
+winding upon itself until the armature reaches the proper position of
+maximum intensity of current production, at which time the circuit is
+broken, as in the former instance. One end of the secondary winding
+(fine wire) is grounded on the live end of the primary, the other end
+being attached to the revolving arm of the distributor mechanism. So
+long as a closed circuit is maintained feeble currents will pass through
+the primary winding, and so long as the contact points are together this
+condition will exist. When the current reaches its maximum value,
+because of the armature being in the best position, the cam operates the
+interrupter and the points are separated, breaking the short circuit
+which has existed in the primary winding.
+
+The secondary circuit has been open while the distributor arm has moved
+from one contact to another and there has been no flow of energy through
+this winding. While the electrical pressure will rise in this, even if
+the distributor arm contacted with one of the segments, there would be
+no spark at the plug until the contact points separated, because the
+current in the secondary winding would not be of sufficient strength.
+When the interrupter operates, however, the maximum primary current will
+be diverted from its short circuit and can flow to the ground only
+through the secondary winding and spark-plug circuit. The high pressure
+now existing in the secondary winding will be greatly increased by the
+sudden flow of primary current, and energy of high enough potential to
+successfully bridge the gap at the plug is thereby produced in the
+winding.
+
+
+THE BERLING MAGNETO
+
+[Illustration: Fig. 63.--Type DD Berling High Tension Magneto.]
+
+The Berling magneto is a true high tension type delivering two impulses
+per revolution, but it is made in a variety of forms, both single and
+double spark. Its principle of action does not differ in essentials from
+the high tension type previously described. This magneto is used on
+Curtiss aviation engines and will deliver sparks in a positive manner
+sufficient to insure ignition of engines up to 200 horse-power and at
+rotative speeds of the magneto armature up to 4,000 r. p. m. which is
+sufficient to take care of an eight-cylinder V engine running up to
+2,000 r. p. m. The magneto is driven at crank-shaft speed on
+four-cylinder engines, at 1-1/2 times crank-shaft speed on six-cylinder
+engines and at twice crank-shaft speed on eight-cylinder V types. The
+types "D" and "DD" BERLING Magnetos are interchangeable with
+corresponding magnetos of other standard makes. The dimensions of the
+four-, six- and eight-cylinder types "D" and "DD" are all the same.
+
+The ideal method of driving the magneto is by means of flexible direct
+connecting coupling to a shaft intended for the purpose of driving the
+magneto. As the magneto must be driven at a high speed, a coupling of
+some flexibility is preferable. The employment of such a coupling will
+facilitate the mounting of the magneto, because a small inaccuracy in
+the lining up of the magneto with the driving shaft will be taken care
+of by the flexible coupling, whereas with a perfectly rigid coupling the
+line-up of the magneto must be absolutely accurate. Another advantage of
+the flexible coupling is that the vibration of the motor will not be as
+fully transmitted to the armature shaft on the magneto as in case a
+rigid coupling is used. This means prolonged life for the magneto.
+
+The next best method of driving the magneto is by means of a gear keyed
+to the armature shaft. When this method of driving is employed, great
+care must be exercised in providing sufficient clearance between the
+gear on the magneto and the driving gear. If there should be a tight
+spot between these two gears it will react disadvantageously on the
+magneto. The third available method is to drive the magneto by means of
+a chain. This is the least desirable of the three methods and should be
+resorted to only in case of absolute necessity. It is difficult to
+provide sufficient clearance when using a chain without rendering the
+timing less accurate and positive.
+
+[Illustration: Fig. 64.--Wiring Diagrams of Berling Magneto Ignition
+Systems.]
+
+Fig. 64, A shows diagrammatically the circuit of the "D" type two-spark
+independent magneto and the switch used with it. In position OFF the
+primary winding of the magneto is short-circuited and in this position
+the switch serves as an ordinary cut-out or grounding switch. In
+position "1" the switch connects the magneto in such a way that it
+operates as an ordinary single-spark magneto. In this position one end
+of the secondary winding is grounded to the body of the motor. This is
+the starting position. In this position of the switch the entire voltage
+generated in the magneto is concentrated at one spark-plug instead of
+being divided in half. With the motor turning over very slowly, as is
+the case in starting, the full voltage generated by the magneto will
+not in all cases be sufficient to bridge simultaneously two spark gaps,
+but is amply sufficient to bridge one. Also, this position of the switch
+tends to retard the ignition and should be used in starting to prevent
+back-firing. With the switch in position "2" the magneto applies
+ignition to both plugs in each cylinder simultaneously. This is the
+normal running position.
+
+Fig. 64, B shows diagrammatically the circuit of the type "DD" BERLING
+high-tension two-spark dual magneto. This type is recommended for
+certain types of heavy-duty airplane motors, which it is impossible to
+turn over fast enough to give the magneto sufficient speed to generate
+even a single spark of volume great enough to ignite the gas in the
+cylinder. The dual feature consists of the addition to the magneto of a
+battery interrupter. The equipment consists of the magneto, coil and
+special high-tension switch. The coil is intended to operate on six
+volts. Either a storage battery or dry cells may be used.
+
+With the switch in the OFF position, the magneto is grounded, and the
+battery circuit is open. With the switch in the second or battery
+position marked "BAT," one end of the secondary winding of the magneto
+is grounded, and the magneto operates as a single-spark magneto
+delivering high-tension current to the inside distributor, and the
+battery circuit being closed the high-tension current from the coil is
+delivered to the outside distributor. In this position the battery
+current is supplied to one set of spark plugs, no matter how slowly the
+motor is turned over, but as soon as the motor starts, the magneto
+supplies current as a single-spark magneto to the other set of the
+spark-plugs. After the engine is running, the switch should be thrown to
+the position marked "MAG." The battery and coil are then disconnected,
+and the magneto furnishes ignition to both plugs in each cylinder. This
+is the normal running position. Either a non-vibrating coil type "N-1"
+is furnished or a combined vibrating and non-vibrating coil type
+"VN-1."
+
+
+SETTING BERLING MAGNETO
+
+The magneto may be set according to one of two different methods, the
+selection of which is, to some extent, governed by the characteristics
+of the engine, but largely due to the personal preference on the part of
+the user. In the first method described below, the most advantageous
+position of the piston for fully advanced ignition is determined in
+relation to the extreme advanced position of the magneto. In this case,
+the fully retarded ignition will not be a matter of selection, but the
+timing range of the magneto is wide enough to bring the fully retarded
+ignition after top-center position of the piston. The second method for
+the setting of the magneto fixes the fully retarded position of the
+magneto in relation to that position of the piston where fully retarded
+ignition is desired. In this case, the extreme advance position of the
+magneto will not always correspond with the best position of the piston
+for fully advanced ignition, and the amount of advance the magneto
+should have to meet ideal requirements in this respect must be
+determined by experiment.
+
+
+_First Method:_
+
+1. Designate one cylinder as cylinder No. 1.
+
+2. Turn the crank-shaft until the piston in cylinder No. 1 is in the
+position where the fully advanced spark is desired to occur.
+
+3. Remove the cover from the distributor block and turn the armature
+shaft in the direction of rotation of the magneto until the distributor
+finger-brush comes into such a position that this brush makes contact
+with the segment which is connected to the cable terminal marked "1."
+This is either one of the two bottom segments, depending upon the
+direction of rotation.
+
+4. Place the cam housing in extreme advance, i.e., turn the cam housing
+until it stops, in the direction opposite to the direction of rotation
+of the armature. With the cam housing in this position, open the cover.
+
+5. With the armature in the approximate position as described in "3,"
+turn the armature slightly in either direction to such a point that the
+platinum points of the magneto interrupter will just begin to open at
+the end of the cam, adjacent to the fibre lever on the interrupter.
+
+6. With this exact position of the armature, fix the magneto to the
+driving member of the engine.
+
+
+_Second Method:_
+
+1. Designate one cylinder as cylinder No. 1.
+
+2. Turn the crank-shaft until the piston in cylinder No. 1 is in the
+position at which the fully retarded spark is desired to occur.
+
+3. Same as No. 3 under First Method.
+
+4. Place the cam housing in extreme retard, i.e., turn the cam housing
+until it stops, in the same direction as the direction of rotation of
+the armature. With the cam housing in this position, open the cover.
+
+5. Same as No. 5 under First Method.
+
+6. Same as No. 6 under First Method.
+
+
+WIRING THE MAGNETO
+
+The wiring of the magneto is clearly shown by wiring diagram.
+
+First determine the sequence of firing for the cylinders and then
+connect the cables to the spark plug in the cylinders in proper
+sequence, beginning with cylinder No. 1 marked on the distributor block.
+
+The switch used with the independent type must be mounted in such a
+manner that there will be a metallic connection between the frame of the
+magneto and the metal portion of the switch.
+
+It is advisable to use a separate battery, either storage or dry cells,
+as a source of current for the dual equipment. Connecting to the same
+battery that is used with the generator and other electrical equipment
+may cause trouble, as a "ground" in this battery causes the coil to
+overheat.
+
+
+CARE AND MAINTENANCE
+
+
+_Lubrication:_
+
+Use only the very best of oil for the oil cups.
+
+Put five drops of oil in the oil cup at the driving end of the magneto
+for every fifty hours of actual running.
+
+Put five drops of oil in the oil cup at the interrupter end of the
+magneto, located at one side of the cam housing, for every hundred hours
+of actual running.
+
+Lubricate the embossed cams in the cam housing with a thin film of
+vaseline every fifty hours of actual running. Wipe off all superfluous
+vaseline. Never use oil in the interrupter. Do not lubricate any other
+part of the interrupter.
+
+
+_Adjusting the Interrupter:_
+
+With the fibre lever in the center of one of the embossed cams, as at
+Fig. 65, the opening between the platinum contacts should be not less
+than .016" and not more than .020". The gauge riveted to the adjusting
+wrench should barely be able to pass between the contacts when fully
+open. The platinum contacts must be smoothed off with a very fine file.
+When in closed position, the platinum contacts should make contact with
+each other over their entire surfaces.
+
+When inspecting the interrupter, make sure that the ground brush in the
+back of the interrupter base is making good contact with the surface on
+which it rubs.
+
+
+_Cleaning the Distributor:_
+
+The distributor block cover should be removed for inspection every
+twenty-five hours of actual running and the carbon deposit from the
+distributor finger-brush wiped off the distributor block by rubbing with
+a rag or piece of waste dipped in gasoline or kerosene. The
+high-tension terminal brush on the side of the magneto should also be
+carefully inspected for proper tension.
+
+
+LOCATING TROUBLE
+
+Trouble in the ignition system is indicated by the motor "missing,"
+stopping entirely, or by inability to start.
+
+It is safe to assume that the trouble is not in the magneto, and the
+carburetor, gasoline supply and spark-plugs should first be
+investigated.
+
+[Illustration: Fig. 65.--The Berling Magneto Breaker Box Showing Contact
+Points Separated and Interruptor Lever on Cam.]
+
+If the magneto is suspected, the first thing to do is to determine if it
+will deliver a spark. To determine this, disconnect one of the
+high-tension leads from the spark-plug in one of the cylinders and place
+it so that there is approximately 1/16" between the terminal and the
+cylinder frame.
+
+Open the pet cocks on the other cylinders to prevent the engine from
+firing and turn over the engine until the piston is approaching the end
+of the compression stroke in the cylinder from which the cable has been
+removed. Set the magneto in the advance position and rapidly rock the
+engine over the top-center position, observing closely if a spark occurs
+between the end of the high-tension cable and the frame.
+
+If the magneto is of the dual type, the trouble may be either in the
+magneto or in the battery or coil system, therefore disconnect the
+battery and place the switch in the position marked "MAG." The magneto
+will then operate as an independent magneto and should spark in the
+proper manner. After this the battery system should be investigated. To
+test the operation of the battery and coil, examine all connections,
+making sure that they are clean and tight, and then with the switch, in
+the "BAT," rock the piston slowly back and forth. If a type "VN-1" coil
+is used, a shower of sparks should jump between the high-tension cable
+terminal and the cylinder frame when the piston is in the correct
+position for firing. If no spark occurs, remove the cover from the coil
+and see that the vibrating tongue is free. If a type "N-1" coil is used,
+a single spark will occur. The battery should furnish six volts when
+connected to the coil, and this should also be verified.
+
+If the coil still refuses to give a spark and all connections are
+correct, the coil should be replaced and the defective coil returned to
+the manufacturer.
+
+If both magneto and coil give a spark when tested as just described, the
+spark-plugs should be investigated. To do this, disconnect the cables
+and remove the spark-plugs. Then reconnect the cables to the plugs and
+place them so that the frame portions of the plugs are in metallic
+connection with the frame of the motor. Then turn over the motor, thus
+revolving the magneto armature, and see if a spark is produced at the
+spark gaps of the plugs.
+
+The most common defects in spark-plugs are breaking down of the
+insulation, fouling due to carbon, or too large or small a spark gap. To
+clean the plugs a stiff brush and gasoline should be used. The spark
+gap should be about 1/32" and never less than 1/64". Too small a gap may
+have been caused by beads of metal forming due to the heat of the spark.
+Too long a gap may have been caused by the points burning off.
+
+If the magneto and spark plugs are in good condition and the engine does
+not run satisfactorily, the setting should be verified according to
+instructions previously given, and, if necessary, readjusted.
+
+[Illustration: Fig. 66.--The Dixie Model 60 for Six-Cylinder Airplane
+Engine Ignition.]
+
+Be careful to observe that both the type "VN-1" and type "N-1" coils are
+so arranged that the spark occurs on the opening of the contacts of the
+timer. As this is just the reverse of the usual operation, it should be
+carefully noted when any change in the setting of the timer is made. The
+timer on the dual type magneto is adjusted so that the battery spark
+occurs about 5° later than the magneto spark. This provides an
+automatic advance as soon as the switch is thrown to the magneto
+position "MAG." This relative timing can be easily adjusted by removing
+the interrupter and shifting the cam in the direction desired.
+
+
+THE DIXIE MAGNETO
+
+[Illustration: Fig. 67.--Installation Dimensions of Dixie Model 60
+Magneto.]
+
+The Dixie magneto, shown at Fig. 66, operates on a different principle
+than the rotary armature type. It is used on the Hall-Scott and other
+aviation engines. In this magneto the rotating member consists of two
+pieces of magnetic material separated by a non-magnetic center piece.
+This member constitutes true rotating poles for the magnet and rotates
+in a field structure, composed of two laminated field pieces, riveted
+between two non-magnetic rings. The bearings for the rotating poles are
+mounted in steel plates, which lie against the poles of the magnets.
+When the magnet poles rotate, the magnetic lines of force from each
+magnet pole are carried directly to the field pieces and through the
+windings, without reversal through the mass of the rotating member and
+with only a single air gap. There are no losses by flux reversal in the
+rotating part, such as take place in other machines, and this is said
+to account for the high efficiency of the instrument.
+
+[Illustration: Fig. 68.--The Rotating Elements of the Dixie Magneto.]
+
+And this "Mason Principle" involved in the operation of the Dixie is
+simplified by a glance at the field structure, consisting of the
+non-magnetic rings, assembled to which are the field pieces between
+which the rotating poles revolve (see Fig. 68). Rotating between the
+limbs of the magnets, these two pieces of magnetic material form true
+extensions to the poles of the magnets, and are, in consequence,
+_always_ of the _same_ polarity. It will be seen there is no reversal of
+the magnetism through them, and consequently no eddy current or
+hysteresis losses which are present in the usual rotor or inductor
+types. The simplicity features of construction stand out prominently
+here, in that there are no revolving windings, a detail entirely
+differing from the orthodox high-tension instrument. This simplicity
+becomes instantly apparent when it is found that the circuit breaker,
+instead of revolving as it does in other types, is stationary and that
+the whole breaker mechanism is exposed by simply turning the cover
+spring aside and removing cover. This makes inspection and adjustment
+particularly simple, and the fact that no special tool is necessary for
+adjustment of the platinum points--an ordinary small screw-driver is the
+whole "kit of tools" needed in the work of disassembling or
+assembling--is a feature of some value.
+
+[Illustration: Fig. 69.--Suggestions for Adjusting and Dismantling Dixie
+Magneto. A--Screw Driver Adjusts Contact Points. B--Distributor Block
+Removed. C--Taking off Magnets. D--Showing How Easily Condenser and High
+Tension Windings are Removed.]
+
+With dust- and water-protecting casing removed, and one of the magnets
+withdrawn, as in Fig. 69, the winding can be seen with its core resting
+on the field pole pieces and the primary lead attached to its side. An
+important feature of the high-tension winding is that the heads are of
+insulating material, and there is not the tendency for the high-tension
+current to jump to the side as in the ordinary armature type magneto.
+The high-tension current is carried to the distributor by means of an
+insulated block with a spindle, at one end of which is a spring brush
+bearing directly on the winding, thus shortening the path of the
+high-tension current and eliminating the use of rubber spools and
+insulating parts. The moving parts of the magneto need never be
+disturbed if the high-tension winding is to be removed. This winding
+constitutes all of the magneto windings, no external spark coil being
+necessary. The condenser is placed directly above the winding and is
+easily removable by taking out two screws, instead of being placed in an
+armature where it is inaccessible except to an expert, and where it
+cannot be replaced except at the factory whence it emanated.
+
+
+CARE OF THE DIXIE MAGNETO
+
+The bearings of the magneto are provided with oil cups and a few drops
+of light oil every 1,000 miles are sufficient. The breaker lever should
+be lubricated every 1,000 miles with a drop of light oil, applied with a
+tooth-pick. The proper distance between the platinum points when
+separated should not exceed .020 or one-fiftieth of an inch. A gauge of
+the proper size is attached to the screwdriver furnished with the
+magneto. The platinum contacts should be kept clean and properly
+adjusted. Should the contacts become pitted, a fine file should be used
+to smooth them in order to permit them to come into perfect contact. The
+distributor block should be removed occasionally and inspected for an
+accumulation of carbon dust. The inside of the distributor block should
+be cleaned with a cloth moistened with gasoline and then wiped dry with
+a clean cloth. When replacing the block, care must be exercised in
+pushing the carbon brush into the socket. Do not pull out the carbon
+brushes in the distributor because you think there is not enough tension
+on the small brass springs. In order to obtain the most efficient
+results, the normal setting of the spark-plug points should not exceed
+.025 of an inch, and it is advisable to have the gap just right before a
+spark-plug is inserted.
+
+The spark-plug electrodes may be easily set by means of the gauge
+attached to the screwdriver. _The setting of the spark-plug points is an
+important function which is usually overlooked, with the result that the
+magneto is blamed when it is not at fault._
+
+
+TIMING OF THE DIXIE MAGNETO
+
+[Illustration: Fig. 69A.--Sectional Views Outlining Construction of
+Dixie Magneto with Compound Distributor for Eight-Cylinder Engine
+Ignition.]
+
+In order to obtain the utmost efficiency from the engine, the magneto
+must be correctly timed to it. This operation is usually performed when
+the magneto is fitted to the engine at the factory. The correct setting
+may vary according to individuality of the engine, and some engines
+may require an earlier setting in order to obtain the best results.
+However, should the occasion arise to retime the magneto, the procedure
+is as follows: Rotate the crank-shaft of the engine until one of the
+pistons, preferably that of cylinder No. 1, is 1/16 of an inch ahead of
+the end of the compression stroke. With the timing lever in full retard
+position, the driving shaft of the magneto should be rotated in the
+direction in which it will be driven. The circuit breaker should be
+closely observed and when the platinum contact points are about to
+separate, the drive gear or coupling should be secured to the drive
+shaft of the magneto. Care should be taken not to alter the position of
+the magneto shaft when tightening the nut to secure the gear or
+coupling, after which the magneto should be secured to its base. Remove
+the distributor block and determine which terminal of the block is in
+contact with the carbon brush of the distributor finger and connect with
+plug wire leading to No. 1 cylinder to this terminal. Connect the
+remaining plug wires in turn according to the proper sequence of firing
+of the cylinders. (See the wiring diagram for a typical six-cylinder
+engine at Fig. 70.) A terminal on the end of the cover spring of the
+magneto is provided for the purpose of connecting the wire leading to a
+ground switch for stopping the engine.
+
+A special model or type of magneto is made for V engines which use a
+compound distributor construction instead of the simple type on the
+model illustrated and a different interior arrangement permits the
+production of four sparks per revolution of the rotors. This makes it
+possible to run the magneto slower than would be possible with the
+two-spark form. The application of two compound distributor magnetos of
+this type to a Thomas-Morse 135 horse-power motor of the eight-cylinder
+V pattern is clearly shown at Fig. 71.
+
+[Illustration: Fig. 70.--Wiring Diagram of Dixie Magneto Installation on
+Hall-Scott Six-Cylinder 125 Horse-Power Aeronautic Motor.]
+
+
+SPARK-PLUG DESIGN AND APPLICATION
+
+[Illustration: Fig. 71.--How Magneto Ignition is Installed on
+Thomas-Morse 135 Horse-Power Motor.]
+
+With the high-tension system of ignition the spark is produced by a
+current of high voltage jumping between two points which break the
+complete circuit, which would exist otherwise in the secondary coil and
+its external connections. The spark-plug is a simple device which
+consists of two terminal electrodes carried in a suitable shell member,
+which is screwed into the cylinder. Typical spark-plugs are shown in
+section at Fig. 72 and the construction can be easily understood. The
+secondary wire from the coil is attached to a terminal at the top of a
+central electrode member, which is supported in a bushing of some form
+of insulating material. The type shown at A employs a molded porcelain
+as an insulator, while that depicted at B uses a bushing of mica. The
+insulating bushing and electrode are housed in a steel body, which is
+provided with a screw thread at the bottom, by which means it is screwed
+into the combustion chamber.
+
+[Illustration: Fig. 72.--Spark-Plug Types Showing Construction and
+Arrangement of Parts.]
+
+When porcelain is used as an insulating material it is kept from direct
+contact with the metal portion by some form of yielding packing, usually
+asbestos. This is necessary because the steel and porcelain have
+different coefficients of expansion and some flexibility must be
+provided at the joints to permit the materials to expand differently
+when heated. The steel body of the plug which is screwed into the
+cylinder is in metallic contact with it and carries sparking points
+which form one of the terminals of the air gap over which the spark
+occurs. The current entering at the top of the plug cannot reach the
+ground, which is represented by the metal portion of the engine, until
+it has traversed the full length of the central electrode and overcome
+the resistance of the gap between it and the terminal point on the
+shell. The porcelain bushing is firmly seated against the asbestos
+packing by means of a brass screw gland which sets against a flange
+formed on the porcelain, and which screws into a thread at the upper
+portion of the plug body.
+
+The mica plug shown at B is somewhat simpler in construction than that
+shown at A. The mica core which keeps the central electrode separated
+from the steel body is composed of several layers of pure sheet mica
+wound around the steel rod longitudinally, and hundreds of stamped steel
+washers which are forced over this member and compacted under high
+pressure with some form of a binding material between them. Porcelain
+insulators are usually molded from high-grade clay and are approximately
+of the shapes desired by the designers of the plug. The central
+electrode may be held in place by mechanical means such as nuts,
+packings, and a shoulder on the rod, as shown at A. Another method
+sometimes used is to cement the electrode in place by means of some form
+of fire-clay cement. Whatever method of fastening is used, it is
+imperative that the joints be absolutely tight so that no gas can escape
+at the time of explosion. Porcelain is the material most widely used
+because it can be glazed so that it will not absorb oil, and it is
+subjected to such high temperature in baking that it is not liable to
+crack when heated.
+
+The spark-plugs may be screwed into any convenient part of the
+combustion chamber, the general practice being to install them in the
+caps over the inlet valves, or in the side of the combustion chamber, so
+the points will be directly in the path of the entering fresh gases from
+the carburetor.
+
+Other insulating materials sometimes used are glass, steatite (which is
+a form of soapstone) and lava. Mica and porcelain are the two common
+materials used because they give the best results. Glass is liable to
+crack, while lava or the soapstone insulating bushings absorb oil. The
+spark gap of the average plug is equal to about 1/32 of an inch for coil
+ignition and 1/40 of an inch when used in magneto circuits. A simple
+gauge for determining the gap setting is the thickness of an ordinary
+visiting card for magneto plugs, or a space equal to the thickness of a
+worn dime for a coil plug. The insulating bushings are made in a number
+of different ways, and while details of construction vary, spark-plugs
+do not differ essentially in design. The dimensions of the standardized
+plug recommended by the S. A. E. are shown at Fig. 73.
+
+[Illustration: Fig. 73.--Standard Airplane Engine Plug Suggested by S.
+A. E. Standards Committee.]
+
+It is often desirable to have a water-tight joint between the
+high-tension cable and the terminal screw on top of the insulating
+bushing of the spark-plug, especially in marine applications. The plug
+shown at C, Fig. 72, is provided with an insulating member or hood of
+porcelain, which is secured by a clip in such a manner that it makes a
+water-tight connection. Should the porcelain of a conventional form of
+plug become covered with water or dirty oil, the high-tension current is
+apt to run down this conducting material on the porcelain and reach the
+ground without having to complete its circuit by jumping the air gap and
+producing a spark. It will be evident that wherever a plug is exposed to
+the elements, which is often the case in airplane service, that it
+should be protected by an insulating hood which will keep the insulator
+dry and prevent short circuiting of the spark. The same end can be
+attained by slipping an ordinary rubber nipple over the porcelain
+insulator of any conventional plug and bringing up one end over the
+cable.
+
+
+TWO-SPARK IGNITION
+
+On most aviation engines, especially those having large cylinders, it is
+sometimes difficult to secure complete combustion by using a
+single-spark plug. If the combustion is not rapid the efficiency of the
+engine will be reduced proportionately. The compressed charge in the
+cylinder does not ignite all at once or instantaneously, as many assume,
+but it is the strata of gas nearest the plug which is ignited first.
+This in turn sets fire to consecutive layers of the charge until the
+entire mass is aflame. One may compare the combustion of gas in the
+gas-engine cylinder to the phenomenon which obtains when a heavy object
+is thrown into a pool of still water. First a small circle is seen at
+the point where the object has passed into the water, this circle in
+turn inducing other and larger circles until the whole surface of the
+pool has been agitated from the one central point. The method of
+igniting the gas is very similar, as the spark ignites the circle of gas
+immediately adjacent to the sparking point, and this circle in turn
+ignites a little larger one concentric with it. The second circle of
+flame sets fire to more of the gas, and finally the entire contents of
+the combustion chamber are burning.
+
+While ordinarily combustion is sufficiently rapid with a single plug so
+that the proper explosion is obtained at moderate engine speeds, if the
+engine is working fast and the cylinders are of large capacity more
+power may be obtained by setting fire to the mixture at two different
+points instead of but one. This may be accomplished by using two
+sparking-plugs in the cylinder instead of one, and experiments have
+shown that it is possible to gain from twenty-five to thirty per cent.
+in motor power at high speed with two-spark plugs, because the
+combustion of gas is accelerated by igniting the gas simultaneously in
+two places. The double-plug system on airplane engines is also a
+safeguard, as in event of failure of one plug in the cylinder the other
+would continue to fire the gas, and the engine will continue to function
+properly.
+
+In using magneto ignition some precautions are necessary relating to
+wiring and also the character of the spark-plugs employed. The conductor
+should be of good quality, have ample insulation, and be well protected
+from accumulations of oil, which would tend to decompose rubber
+insulation. It is customary to protect the wiring by running it through
+the conduits of fiber or metal tubing lined with insulating material.
+Multiple strand cables should be used for both primary and secondary
+wiring, and the insulation should be of rubber at least 3/16 inch thick.
+
+The spark-plugs commonly used for battery and coil ignition cannot
+always be employed when a magneto is fitted. The current produced by the
+mechanical generator has a greater amperage and more heat value than
+that obtained from transformer coils excited by battery current. The
+greater heat may burn or fuse the slender points used on some battery
+plugs and heavier electrodes are needed to resist the heating effect of
+the more intense arc. While the current has greater amperage it is not
+of as high potential or voltage as that commonly produced by the
+secondary winding of an induction coil, and it cannot overcome as much
+of a gap. Manufacturers of magneto plugs usually set the spark points
+about 1/64 of an inch apart. The most efficient magneto plug has a
+plurality of points so that when the distance between one set becomes
+too great the spark will take place between one of the other pairs of
+electrodes which are not separated by so great an air space.
+
+[Illustration: Fig. 74.--Special Mica Plug for Aviation Engines.]
+
+
+SPECIAL PLUGS FOR AIRPLANE WORK
+
+Airplane work calls for special construction of spark-plugs, owing to
+the high compression used in the engines and the fact that they are
+operated on open throttle practically all the time, thus causing a great
+deal of heat to be developed. The plug shown at Fig. 74 was recently
+described in "The Automobile," and has been devised especially for
+airplane engines and automobile racing power plants. The core C is built
+up of mica washers, and has square shoulders. As mica washers of
+different sizes may be used, and accurate machining, such as is
+necessary with conical clamping surfaces, is not required, the plug can
+be produced economically. The square shoulders of the core afford two
+gasket seats, and when the core is clamped in the shell by means of
+check nut E, it is accurately centered and a tight joint is formed. This
+construction also makes a shorter plug than where conical fits are used,
+thus improving the heat radiation through the stem. The lower end of the
+shell is provided with a baffle plate O, which tends to keep the oil
+away from the mica. There are perforations L in this baffle plate to
+prevent burnt gases being pocketed behind the baffle plate and
+pre-igniting the new charge. This construction also brings the firing
+point out into the firing chamber of the engine, and has all the other
+advantages of a closed-end plug. The stem P is made of brass or copper,
+on account of their superior heat conductivity, and the electrode J is
+swedged into the bottom of the stem, as shown at K, in a secure manner.
+
+The shell is finned, as shown at G, to provide greater heat radiating
+surface. There is also a fin F at the top of the stem, to increase the
+radiation of heat from the stem and electrode. The top of this finned
+portion is slightly countersunk, and the stem is riveted into same,
+thereby reducing the possibility of leakage past the threads on the
+stem. This finned portion is necked at A to take a slip terminal.
+
+In building up the core a small section of washers, I, is built up
+before the mica insulating tube D is placed on. This construction gives
+a better support to section I. Baffle plate O is bored out to allow the
+electrode J to pass through, and the clearance between baffle plate and
+electrode is made larger than the width of the gap between the firing
+points, so that there is no danger of the spark jumping from the
+electrode to the baffle plate.
+
+This plug will be furnished either with or without the finned portion,
+to meet individual requirements. The manufacturers lay special stress
+upon the simplicity of construction and upon the method of clamping,
+which is claimed to make the plug absolutely gas-tight.
+
+
+
+
+CHAPTER VII
+
+    Why Lubrication Is Necessary--Friction Defined--Theory of
+    Lubrication--Derivation of Lubricants--Properties of Cylinder
+    Oils--Factors Influencing Lubrication System Selection--Gnome
+    Type Engines Use Castor Oil--Hall-Scott Lubrication System--Oil
+    Supply by Constant Level Splash System--Dry Crank-Case System
+    Best for Airplane Engines--Why Cooling Systems Are Necessary--
+    Cooling Systems Generally Applied--Cooling by Positive Pump
+    Circulation--Thermo-Syphon System--Direct Air-Cooling Methods--
+    Air-Cooled Engine Design Considerations.
+
+
+WHY LUBRICATION IS NECESSARY
+
+The importance of minimizing friction at the various bearing surfaces of
+machines to secure mechanical efficiency is fully recognized by all
+mechanics, and proper lubricity of all parts of the mechanism is a very
+essential factor upon which the durability and successful operation of
+the motor car power plant depends. All of the moving members of the
+engine which are in contact with other portions, whether the motion is
+continuous or intermittent, of high or low velocity, or of rectilinear
+or continued rotary nature, should be provided with an adequate supply
+of oil. No other assemblage of mechanism is operated under conditions
+which are so much to its disadvantage as the motor car, and the tendency
+is toward a simplification of oiling methods so that the supply will be
+ample and automatically applied to the points needing it.
+
+In all machinery in motion the members which are in contact have a
+tendency to stick to each other, and the very minute projections which
+exist on even the smoothest of surfaces would have a tendency to cling
+or adhere to each other if the surfaces were not kept apart by some
+elastic and unctuous substance. This will flow or spread out over the
+surfaces and smooth out the inequalities existing which tend to produce
+heat and retard motion of the pieces relative to each other.
+
+A general impression which obtains is that well machined surfaces are
+smooth, but while they are apparently free from roughness, and no
+projections are visible to the naked eye, any smooth bearing surface,
+even if very carefully ground, will have a rough appearance if examined
+with a magnifying glass. An exaggerated condition to illustrate this
+point is shown at Fig. 75. The amount of friction will vary in
+proportion to the pressure on the surfaces in contact and will augment
+as the loads increase; the rougher surfaces will have more friction than
+smoother ones and soft bodies will produce more friction than hard
+substances.
+
+
+FRICTION DEFINED
+
+Friction is always present in any mechanism as a resisting force that
+tends to retard motion and bring all moving parts to a state of rest.
+The absorption of power by friction may be gauged by the amount of heat
+which exists at the bearing points. Friction of solids may be divided
+into two classes: sliding friction, such as exists between the piston
+and cylinder, or the bearings of a gas-engine, and rolling friction,
+which is that present when the load is supported by ball or roller
+bearings, or that which exists between the tires or the driving wheels
+and the road. Engineers endeavor to keep friction losses as low as
+possible, and much care is taken in all modern airplane engines to
+provide adequate methods of lubrication, or anti-friction bearings at
+all points where considerable friction exists.
+
+
+THEORY OF LUBRICATION
+
+The reason a lubricant is supplied to bearing points will be easily
+understood if one considers that these elastic substances flow between
+the close fitting surfaces, and by filling up the minute depressions in
+the surfaces and covering the high spots act as a cushion which absorbs
+the heat generated and takes the wear instead of the metallic bearing
+surface. The closer the parts fit together the more fluid the lubricant
+must be to pass between their surfaces, and at the same time it must
+possess sufficient body so that it will not be entirely forced out by
+the pressure existing between the parts.
+
+[Illustration: Fig. 75.--Showing Use of Magnifying Glass to Demonstrate
+that Apparently Smooth Metal Surfaces May Have Minute Irregularities
+which Produce Friction.]
+
+Oils should have good adhesive, as well as cohesive, qualities. The
+former are necessary so that the oil film will cling well to the
+surfaces of the bearings; the latter, so the oil particles will cling
+together and resist the tendency to separation which exists all the time
+the bearings are in operation. When used for gas-engine lubrication the
+oil should be capable of withstanding considerable heat in order that it
+will not be vaporized by the hot portions of the cylinder. It should
+have sufficient cold test so that it will remain fluid and flow readily
+at low temperature. Lubricants should be free from acid, or alkalies,
+which tend to produce a chemical action with metals and result in
+corrosion of the parts to which they are applied. It is imperative that
+the oil be exactly the proper quality and nature for the purpose
+intended and that it be applied in a positive manner. The requirements
+may be briefly summarized as follows:
+
+First--It must have sufficient body to prevent seizing of the parts to
+which it is applied and between which it is depended upon to maintain an
+elastic film, and yet it must not have too much viscosity, in order to
+minimize the internal or fluid friction which exists between the
+particles of the lubricant itself.
+
+Second--The lubricant must not coagulate or gum; must not injure the
+parts to which it is applied, either by chemical action or by producing
+injurious deposits, and it should not evaporate readily.
+
+Third--The character of the work will demand that the oil should not
+vaporize when heated or thicken to such a point that it will not flow
+readily when cold.
+
+Fourth--The oil must be free from acid, alkalies, animal or vegetable
+fillers, or other injurious agencies.
+
+Fifth--It must be carefully selected for the work required and should be
+a good conductor of heat.
+
+
+DERIVATION OF LUBRICANTS
+
+The first oils which were used for lubricating machinery were obtained
+from animal and vegetable sources, though at the present time most
+unguents are of mineral derivation. Lubricants may exist as fluids,
+semifluids, or solids. The viscosity will vary from light spindle or
+dynamo oils, which have but little more body than kerosene, to the
+heaviest greases and tallows. The most common solid employed as a
+lubricant is graphite, sometimes termed "plumbago" or "black lead." This
+substance is of mineral derivation.
+
+The disadvantage of oils of organic origin, such as those obtained from
+animal fats or vegetable substances, is that they will absorb oxygen
+from the atmosphere, which causes them to thicken or become rancid.
+Such oils have a very poor cold test, as they solidify at comparatively
+high temperatures, and their flashing point is so low that they cannot
+be used at points where much heat exists. In most animal oils various
+acids are present in greater or less quantities, and for this reason
+they are not well adapted for lubricating metallic surfaces which may be
+raised high enough in temperature to cause decomposition of the oils.
+
+Lubricants derived from the crude petroleum are called "Oleonaphthas"
+and they are a product of the process of refining petroleum through
+which gasoline and kerosene are obtained. They are of lower cost than
+vegetable or animal oil, and as they are of non-organic origin, they do
+not become rancid or gummy by constant exposure to the air, and they
+will have no corrosive action on metals because they contain no
+deleterious substances in chemical composition. By the process of
+fractional distillation mineral oils of all grades can be obtained. They
+have a lower cold and higher flash test and there is not the liability
+of spontaneous combustion that exists with animal oils.
+
+The organic oils are derived from fatty substances, which are present in
+the bodies of all animals and in some portions of plants. The general
+method of extracting oil from animal bodies is by a rendering process,
+which consists of applying sufficient heat to liquefy the oil and then
+separating it from the tissue with which it is combined by compression.
+The only oil which is used to any extent in gas-engine lubrication that
+is not of mineral derivation is castor oil. This substance has been used
+on high-speed racing automobile engines and on airplane power plants. It
+is obtained from the seeds of the castor plant, which contain a large
+percentage of oil.
+
+Among the solid substances which may be used for lubricating purposes
+may be mentioned tallow, which is obtained from the fat of animals, and
+graphite and soapstone, which are of mineral derivation. Tallow is
+never used at points where it will be exposed to much heat, though it
+is often employed as a filler for greases used in transmission gearing
+of autos. Graphite is sometimes mixed with oil and applied to cylinder
+lubrication, though it is most often used in connection with greases in
+the landing gear parts and for coating wires and cables of the airplane.
+Graphite is not affected by heat, cold, acids, or alkalies, and has a
+strong attraction for metal surfaces. It mixes readily with oils and
+greases and increases their efficiency in many applications. It is
+sometimes used where it would not be possible to use other lubricants
+because of extremes of temperature.
+
+The oils used for cylinder lubrication are obtained almost exclusively
+from crude petroleum derived from American wells. Special care must be
+taken in the selection of crude material, as every variety will not
+yield oil of the proper quality to be used as a cylinder lubricant. The
+crude petroleum is distilled as rapidly as possible with fire heat to
+vaporize off the naphthas and the burning oils. After these vapors have
+been given off superheated steam is provided to assist in distilling.
+When enough of the light elements have been eliminated the residue is
+drawn off, passed through a strainer to free it from grit and earthy
+matters, and is afterwards cooled to separate the wax from it. This is
+the dark cylinder oil and is the grade usually used for steam-engine
+cylinders.
+
+
+PROPERTIES OF CYLINDER OILS
+
+The oil that is to be used in the gasoline engine must be of high
+quality, and for that reason the best grades are distilled in a vacuum
+that the light distillates may be separated at much lower temperatures
+than ordinary conditions of distilling permit. If the degree of heat is
+not high the product is not so apt to decompose and deposit carbon. If
+it is desired to remove the color of the oil which is caused by free
+carbon and other impurities it can be accomplished by filtering the oil
+through charcoal. The greater the number of times the oil is filtered,
+the lighter it will become in color. The best cylinder oils have flash
+points usually in excess of 500 degrees F., and while they have a high
+degree of viscosity at 100 degrees F. they become more fluid as the
+temperature increases.
+
+The lubricating oils obtained by refining crude petroleum may be divided
+into three classes:
+
+First--The natural oils of great body which are prepared for use by
+allowing the crude material to settle in tanks at high temperature and
+from which the impurities are removed by natural filtration. These oils
+are given the necessary body and are free from the volatile substances
+they contain by means of superheated steam which provides a source of
+heat.
+
+Second--Another grade of these natural oils which are filtered again at
+high temperatures and under pressure through beds of animal charcoal to
+improve their color.
+
+Third--Pale, limpid oils, obtained by distillation and subsequent
+chemical treatment from the residuum produced in refining petroleum to
+obtain the fuel oils.
+
+Authorities agree that any form of mixed oil in which animal and mineral
+lubricants are combined should never be used in the cylinder of a gas
+engine as the admixture of the lubricants does not prevent the
+decomposition of the organic oil into the glycerides and fatty acids
+peculiar to the fat used. In a gas-engine cylinder the flame tends to
+produce more or less charring. The deposits of carbon will be much
+greater with animal oils than with those derived from the petroleum base
+because the constituents of a fat or tallow are not of the same volatile
+character as those which comprise the hydro-carbon oils which will
+evaporate or volatilize before they char in most instances.
+
+
+FACTORS INFLUENCING LUBRICATION SYSTEM SELECTION
+
+The suitability of oil for the proper and efficient lubrication of all
+internal combustion engines is determined chiefly by the following
+factors:
+
+1. Type of cooling system (operating temperatures).
+
+2. Type of lubricating system (method of applying oil to the moving
+parts).
+
+3. Rubbing speeds of contact surfaces.
+
+Were the operating temperatures, bearing surface speeds and lubrication
+systems identical, a single oil could be used in all engines with equal
+satisfaction. The only change then necessary in viscosity would be that
+due to climatic conditions. As engines are now designed, only three
+grades of oil are necessary for the lubrication of all types with the
+exception of Knight, air-cooled and some engines which run continuously
+at full load. In the specification of engine lubricants the feature of
+load carried by the engine should be carefully considered.
+
+_Full Load Engines._
+
+  1. Marine.
+  2. Racing automobile.
+  3. Aviation.
+  4. Farm tractor.
+  5. Some stationary.
+
+_Variable Load Engines._
+
+  1. Pleasure automobile.
+  2. Commercial vehicle.
+  3. Motor cycle.
+  4. Some stationary.
+
+Of the forms outlined, the only one we have any immediate concern about
+is the airplane power plant. The Platt & Washburn Refining Company, who
+have made a careful study of the lubrication problem as applied to all
+types of engines, have found a peculiar set of conditions to apply to
+oiling high-speed constant-duty or "full-load" engines. Modern airplane
+engines are designed to operate continuously at a fairly uniform high
+rotative speed and at full load over long periods of time. As a sequence
+to this heavy duty the operating temperatures are elevated. For the
+sake of extreme lightness in weight of all parts, very thin alloy steel
+aluminum or cast iron pistons are fitted and the temperature of the thin
+piston heads at the center reaches anywhere between 600° and 1,400°
+Fahr., as in automobile racing engines. Freely exposed to such intense
+heat hydro-carbon oils are partially "cracked" into light and heavy
+products or polymerized into solid hydro-carbons. From these facts it
+follows that only heavy mineral oils of low carbon residue and of the
+greatest chemical purity and stability should be used to secure good
+lubrication. In all cases the oil should be sufficiently heavy to assure
+the highest horse-power and fuel and oil economy compatible with perfect
+lubrication, avoiding, at the same time, carbonization and ignition
+failure. When aluminum pistons are used their superior heat-conducting
+properties aid materially in reducing the rate of oil destruction.
+
+The extraordinary evolutions described by airplanes in flight make it a
+matter of vital necessity to operate engines inclined at all angles to
+the vertical as well as in an upside-down position. To meet this
+situation lubricating systems have been elaborated so as to deliver an
+abundance of oil where needed and to eliminate possible flooding of
+cylinders. This is done by applying a full force feed system,
+distributing oil under considerable pressure to all working parts.
+Discharged through the bearings, the oil drains down to the suction side
+of a second pump located in the bottom of the base chamber. This pump
+being of greater capacity than the first prevents the accumulation of
+oil in the crank-case, and forces it to a separate oil reservoir-cooler,
+whence it flows back in rapid circulation to the pump feeding the
+bearings. With this arrangement positive lubrication is entirely
+independent of engine position. The lubricating system of the
+Thomas-Morse aviation engines, which is shown at Fig. 76, is typical of
+current practice.
+
+[Illustration: Fig. 76.--Pressure Feed Oiling System of Thomas Aviation
+Engine Includes Oil Cooling Means.]
+
+
+GNOME TYPE ENGINES USE CASTOR OIL
+
+The construction and operation of rotative radial cylinder engines
+introduce additional difficulties of lubrication to those already
+referred to and merit especial attention. Owing to the peculiar
+alimentation systems of Gnome type engines, atomized gasoline mixed with
+air is drawn through the hollow stationary crank-shaft directly into the
+crank-case which it fills on the way to the cylinders. Therein lies the
+trouble. Hydrocarbon oils are soon dissolved by the gasoline and washed
+off, leaving the bearing surfaces without adequate protection and
+exposed to instant wear and destruction. So castor oil is resorted to as
+an indispensable but unfortunate compromise. Of vegetable origin, it
+leaves a much more bulky carbon deposit in the explosion chambers than
+does mineral oil and its great affinity for oxygen causes the formation
+of voluminous gummy deposit in the crank-case. Engines employing it need
+to be dismounted and thoroughly scraped out at frequent intervals. It is
+advisable to use only unblended chemically pure castor oil in rotative
+engines, first by virtue of its insolubility in gasoline and second
+because its extra heavy body can resist the high temperature of
+air-cooled cylinders.
+
+
+HALL-SCOTT LUBRICATION SYSTEM
+
+[Illustration: Fig. 77.--Diagram of Oiling System, Hall-Scott Type A 125
+Horse-Power Engine.]
+
+The oiling system of the Hall-Scott type A-5 125 horse-power engine is
+clearly shown at Fig. 77. It is completely described in the instruction
+book issued by the company from which the following extracts are
+reproduced by permission. Crank-shaft, connecting rods and all other
+parts within the crank-case and cylinders are lubricated directly or
+indirectly by a force-feed oiling system. The cylinder walls and wrist
+pins are lubricated by oil spray thrown from the lower end of connecting
+rod bearings. This system is used only upon A-5 engines. Upon A-7a and
+A-5a engines a small tube supplies oil from connecting rod bearing
+directly upon the wrist pin. The oil is drawn from the strainer located
+at the lowest portion of the lower crank-case, forced around the main
+intake manifold oil jacket. From here it is circulated to the main
+distributing pipe located along the lower left hand side of upper
+crank-case. The oil is then forced directly to the lower side of
+crank-shaft, through holes drilled in each main bearing cup. Leakage
+from these main bearings is caught in scuppers placed upon the cheeks of
+the crank-shafts furnishing oil under pressure to the connecting rod
+bearings. A-7a and A-5a engines have small tubes leading from these
+bearings which convey the oil under pressure to the wrist pins.
+
+A bi-pass located at the front end of the distributing oil pipe can be
+regulated to lessen or raise the pressure. By screwing the valve in, the
+pressure will raise and more oil will be forced to the bearings. By
+unscrewing, pressure is reduced and less oil is fed. A-7a and A-5a
+engines have oil relief valves located just off of the main oil pump in
+the lower crank-case. This regulates the pressure at all times so that
+in cold weather there will be no danger of bursting oil pipes due to
+excessive pressure. If it is found the oil pressure is not maintained at
+a high enough level, inspect this valve. A stronger spring will not
+allow the oil to bi-pass so freely, and consequently the pressure will
+be raised; a weaker spring will bi-pass more oil and reduce the oil
+pressure materially. Independent of the above-mentioned system, a small,
+directly driven rotary oiler feeds oil to the base of each individual
+cylinder. The supply of oil is furnished by the main oil pump located in
+the lower crank-case. A small sight-feed regulator is furnished to
+control the supply of oil from this oiler. This instrument should be
+placed higher than the auxiliary oil distributor itself to enable the
+oil to drain by gravity feed to the oiler. If there is no available
+place with the necessary height in the front seat of plane, connect it
+directly to the intake L fitting on the oiler in an upright position. It
+should be regulated with full open throttle to maintain an oil level in
+the glass, approximately half way.
+
+An oil pressure gauge is provided. This should be run to the pilot's
+instrument board. The gauge registers the oil pressure upon the
+bearings, also determining its circulation. Strict watch should be
+maintained of this instrument by pilot, and if for any reason its hand
+should drop to 0 the motor should be immediately stopped and the trouble
+found before restarting engine. Care should be taken that the oil does
+not work up into the gauge, as it will prevent the correct gauge
+registering of oil pressure. The oil pressure will vary according to
+weather conditions and viscosity of oil used. In normal weather, with
+the engine properly warmed up, the pressure will register on the oil
+gauge from 5 to 10 pounds when the engine is turning from 1,275 to 1,300
+r. p. m. This does not apply to all aviation engines, however, as the
+proper pressure advised for the Curtiss OX-2 motor is from 40 to 55
+pounds at the gauge.
+
+The oil sump plug is located at the lowest point of the lower
+crank-case. This is a combination dirt, water and sediment trap. It is
+easily removed by unscrewing. Oil is furnished mechanically to the
+cam-shaft housing under pressure through a small tube leading from the
+main distributing pipe at the propeller end of engine directly into the
+end of cam-shaft housing. The opposite end of this housing is amply
+relieved to allow the oil to rapidly flow down upon cam-shaft, magneto,
+pinion-shaft, and crank-shaft gears, after which it returns to lower
+crank-case. An outside overflow pipe is also provided to carry away the
+surplus oil.
+
+
+DRAINING OIL FROM CRANK-CASE
+
+The oil strainer is placed at the lowest point of the lower crank-case.
+This strainer should be removed after every five to eight hours running
+of the engine and cleaned thoroughly with gasoline. It is also advisable
+to squirt distillate up into the case through the opening where the
+strainer has been removed. Allow this distillate to drain out thoroughly
+before replacing the plug with strainer attached. Be sure gasket is in
+place on plug before replacing. Pour new oil in through either of the
+two breather pipes on exhaust side of motor. Be sure to replace strainer
+screens if removed. If, through oversight, the engine does not receive
+sufficient lubrication and begins to heat or pound, it should be stopped
+immediately. After allowing engine to cool pour at least three gallons
+of oil into oil sump. Fill radiator with water after engine has cooled.
+Should there be apparent damage, the engine should be thoroughly
+inspected immediately without further running. If no obvious damage has
+been done, the engine should be given a careful examination at the
+earliest opportunity to see that the running without oil has not burned
+the bearings or caused other trouble.
+
+Oils best adapted for Hall-Scott engines have the following properties:
+A flash test of not less than 400° F.; viscosity of not less than 75 to
+85 taken at 21° F. with Saybolt's Universal Viscosimeter.
+
+_Zeroline heavy duty oil_, manufactured by the Standard Oil Company of
+California; also,
+
+_Gargoyle mobile B oil_, manufactured by the Vacuum Oil Company, both
+fulfill the above specifications. One or the other of these oils can be
+obtained all over the world.
+
+Monogram extra heavy is also recommended.
+
+
+OIL SUPPLY BY CONSTANT LEVEL SPLASH SYSTEM
+
+The splash system of lubrication that depends on the connecting rod to
+distribute the lubricant is one of the most successful and simplest
+forms for simple four- and six-cylinder vertical automobile engines, but
+is not as well adapted to the oiling of airplane power plants for
+reasons previously stated. If too much oil is supplied the surplus will
+work past the piston rings and into the combustion chamber, where it
+will burn and cause carbon deposits. Too much oil will also cause an
+engine to smoke and an excess of lubricating oil is usually manifested
+by a bluish-white smoke issuing from the exhaust.
+
+A good method of maintaining a constant level of oil for the successful
+application of the splash system is shown at Fig. 78. The engine base
+casting includes a separate chamber which serves as an oil container and
+which is below the level of oil in the crank-case. The lubricant is
+drawn from the sump or oil container by means of a positive oil pump
+which discharges directly into the engine case. The level is maintained
+by an overflow pipe which allows all excess lubricant to flow back into
+the oil container at the bottom of the cylinder. Before passing into the
+pump again the oil is strained or filtered by a screen of wire gauze and
+all foreign matter removed. Owing to the rapid circulation of the oil it
+may be used over and over again for quite a period of time. The oil is
+introduced directly into the crank-case by a breather pipe and the level
+is indicated by a rod carried by a float which rises when the container
+is replenished and falls when the available supply diminishes. It will
+be noted that with such system the only apparatus required besides the
+oil tank which is cast integral with the bottom of the crank-case is a
+suitable pump to maintain circulation of oil. This member is always
+positively driven, either by means of shaft and universal coupling or
+direct gearing. As the system is entirely automatic in action, it will
+furnish a positive supply of oil at all desired points, and it cannot be
+tampered with by the inexpert because no adjustments are provided or
+needed.
+
+
+DRY CRANK-CASE SYSTEM BEST FOR AIRPLANE ENGINES
+
+[Illustration: Fig. 78.--Sectional View of Typical Motor Showing Parts
+Needing Lubrication and Method of Applying Oil by Constant Level Splash
+System. Note also Water Jacket and Spaces for Water Circulation.]
+
+In most airplane power plants it is considered desirable to supply the
+oil directly to the parts needing it by suitable leads instead of
+depending solely upon the distributing action of scoops on the
+connecting rod big ends. A system of this nature is shown at Fig. 77.
+The oil is carried in the crank-case, as is common practice, but the
+normal oil level is below the point where it will be reached by the
+connecting rod. It is drawn from the crank-case by a plunger pump which
+directs it to a manifold leading directly to conductors which supply the
+main journals. After the oil has been used on these points it drains
+back into the bottom of the crank-case. An excess is provided which is
+supplied to the connecting rod ends by passages drilled into the webs of
+the crank-shaft and part way into the crank-pins as shown by the dotted
+lines. The oil which is present at the connecting rod crank-pins is
+thrown off by centrifugal force and lubricates the cylinder walls and
+other internal parts. Regulating screws are provided so that the amount
+of oil supplied the different points may be regulated at will. A relief
+check valve is installed to take care of excess lubricant and to allow
+any oil that does not pass back into the pipe line to overflow or
+bi-pass into the main container.
+
+[Illustration: Fig. 79.--Pressure Feed Oil-Supply System of Airplane
+Power Plants has Many Good Features.]
+
+A simple system of this nature is shown graphically in a phantom view of
+the crank-case at Fig. 79, in which the oil passages are made specially
+prominent. The oil is taken from a reservoir at the bottom of the engine
+base by the usual form of gear oil pump and is supplied to a main feed
+manifold which extends the length of the crank-case. Individual
+conductors lead to the five main bearings, which in turn supply the
+crank-pins by passages drilled through the crank-shaft web. In this
+power plant the connecting rods are hollow section bronze castings and
+the passage through the center of the connecting rod serves to convey
+the lubricant from the crank-pins to the wrist-pins. The cylinder walls
+are oiled by the spray of lubricant thrown off the revolving crank-shaft
+by centrifugal force. Oil projection by the dippers on the connecting
+rod ends from constant level troughs is unequal upon the cylinder walls
+of the two-cylinder blocks of an eight- or twelve-cylinder V engine.
+This gives rise, on one side of the engine, to under-lubrication, and,
+on the other side, to over-lubrication, as shown at Fig. 80, A. This
+applies to all modifications of splash lubricating systems.
+
+When a force-feed lubricating system is used, the oil, escaping past the
+cheeks of both ends of the crank-pin bearings, is thrown off at a
+tangent to the crank-pin circle in all directions, supplying the
+cylinders on both sides with an equal quantity of oil, as at Fig. 80, B.
+
+
+WHY COOLING SYSTEMS ARE NECESSARY
+
+The reader should understand from preceding chapters that the power of
+an internal-combustion motor is obtained by the rapid combustion and
+consequent expansion of some inflammable gas. The operation in brief is
+that when air or any other gas or vapor is heated, it will expand and
+that if this gas is confined in a space which will not permit expansion,
+pressure will be exerted against all sides of the containing chamber.
+The more a gas is heated, the more pressure it will exert upon the walls
+of the combustion chamber it confines. Pressure in a gas may be
+created by increasing its temperature and inversely heat may be created
+by pressure. When a gas is compressed its total volume is reduced and
+the temperature is augmented.
+
+[Illustration: Fig. 80.--Why Pressure Feed System is Best for
+Eight-Cylinder Vee Airplane Engines.]
+
+The efficiency of any form of heat engine is determined by the power
+obtained from a certain fuel consumption. A definite amount of energy
+will be liberated in the form of heat when a pound of any fuel is
+burned. The efficiency of any heat engine is proportional to the power
+developed from a definite quantity of fuel with the least loss of
+thermal units. If the greater proportion of the heat units derived by
+burning the explosive mixture could be utilized in doing useful work,
+the efficiency of the gasoline engine would be greater than that of any
+other form of energizing power. There is a great loss of heat from
+various causes, among which can be cited the reduction of pressure
+through cooling the motor and the loss of heat through the exhaust
+valves when the burned gases are expelled from the cylinder.
+
+The loss through the water jacket of the average automobile power plant
+is over 50 per cent. of the total fuel efficiency. This means that more
+than half of the heat units available for power are absorbed and
+dissipated by the cooling water. Another 16 per cent. is lost through
+the exhaust valve, and but 33-1/3 per cent. of the heat units do useful
+work. The great loss of heat through the cooling systems cannot be
+avoided, as some method must be provided to keep the temperature of the
+engine within proper bounds. It is apparent that the rapid combustion
+and continued series of explosions would soon heat the metal portions of
+the engine to a red heat if some means were not taken to conduct much of
+this heat away. The high temperature of the parts would burn the
+lubricating oil, even that of the best quality, and the piston and rings
+would expand to such a degree, especially when deprived of oil, that
+they would seize in the cylinder. This would score the walls, and the
+friction which ensued would tend to bind the parts so tightly that the
+piston would stick, bearings would be burned out, the valves would warp,
+and the engine would soon become inoperative.
+
+[Illustration: Fig. 81.--Operating Temperatures of Automobile Engine
+Parts Useful as a Guide to Understand Airplane Power Plant Heat.]
+
+The best temperature to secure efficient operation is one on which
+considerable difference of opinion exists among engineers. The fact that
+the efficiency of an engine is dependent upon the ratio of heat
+converted into useful work compared to that generated by the explosion
+of the gas is an accepted fact. It is very important that the engine
+should not get too hot, and on the other hand it is equally vital that
+the cylinders be not robbed of too much heat. The object of cylinder
+cooling is to keep the temperature of the cylinder below the danger
+point, but at the same time to have it as high as possible to secure
+maximum power from the gas burned. The usual operating temperatures of
+an automobile engine are shown at Fig. 81, and this can be taken as an
+approximation of the temperatures apt to exist in an airplane engine of
+conventional design as well when at ground level or not very high in the
+air. The newer very high compression airplane engines in which
+compressions of eight or nine atmospheres are used, or about 125 pounds
+per square inch, will run considerably hotter than the temperatures
+indicated.
+
+
+COOLING SYSTEMS GENERALLY APPLIED
+
+There are two general systems of engine cooling in common use, that in
+which water is heated by the absorption of heat from the engine and then
+cooled by air, and the other method in which the air is directed onto
+the cylinder and absorbs the heat directly instead of through the medium
+of water. When the liquid is employed in cooling it is circulated
+through jackets which surround the cylinder casting and the water may be
+kept in motion by two methods. The one generally favored is to use a
+positive circulating pump of some form which is driven by the engine to
+keep the water in motion. The other system is to utilize a natural
+principle that heated water is lighter than cold liquid and that it will
+tend to rise to the top of the cylinder when it becomes heated to the
+proper temperature and cooled water takes its place at the bottom of the
+water jacket.
+
+Air-cooling methods may be by radiation or convection. In the former
+case the effective outer surface of the cylinder is increased by the
+addition of flanges machined or cast thereon, and the air is depended on
+to rise from the cylinder as heated and be replaced by cooler air. This,
+of course, is found only on stationary engines. When a positive air
+draught is directed against the cylinder by means of the propeller slip
+stream in an airplane, cooling is by convection and radiation both.
+Sometimes the air draught may be directed against the cylinder walls by
+some form of jacket which confines it to the heated portions of the
+cylinder.
+
+
+COOLING BY POSITIVE WATER CIRCULATION
+
+[Illustration: Fig. 82.--Water Cooling of Salmson Seven-Cylinder Radial
+Airplane Engine.]
+
+A typical water-cooling system in which a pump is depended upon to
+promote circulation of the cooling liquid is shown at Figs. 82 and 83.
+The radiator is carried at the front end of the fuselage in most cases,
+and serves as a combined water tank and cooler, but in some cases it is
+carried at the side of the engine, as in Fig. 84, or attached to the
+central portion of the aerofoil or wing structure. It is composed of an
+upper and lower portion joined together by a series of pipes which may
+be round and provided with a series of fins to radiate the heat, or
+which may be flat in order to have the water pass through in thin sheets
+and cool it more easily. Cellular or honeycomb coolers are composed of a
+large number of bent tubes which will expose a large area of surface to
+the cooling influence of the air draught forced through the radiator
+either by the forward movement of the vehicle or by some type of fan.
+The cellular and flat tube types have almost entirely displaced the
+flange tube radiators which were formerly popular because they cool the
+water more effectively, and may be made lighter than the tubular
+radiator could be for engines of the same capacity.
+
+[Illustration: Fig. 83.--How Water Cooling System of Thomas Airplane
+Engine is Installed in Fuselage.]
+
+The water is drawn from the lower header of the radiator by the pump and
+is forced through a manifold to the lower portion of the water jackets
+of the cylinder. It becomes heated as it passes around the cylinder
+walls and combustion chambers and the hot water passes out of the top of
+the water jacket to the upper portion of the radiator. Here it is
+divided in thin streams and directed against comparatively cool metal
+which abstracts the heat from the water. As it becomes cooler it falls
+to the bottom of the radiator because its weight increases as the
+temperature becomes lower. By the time it reaches the lower tank of the
+radiator it has been cooled sufficiently so that it may be again passed
+around the cylinders of the motor. The popular form of circulating pump
+is known as the "centrifugal type" because a rotary impeller of
+paddle-wheel form throws water which it receives at a central point
+toward the outside and thus causes it to maintain a definite rate of
+circulation. The pump is always a separate appliance attached to the
+engine and driven by positive gearing or direct-shaft connection. The
+centrifugal pump is not as positive as the gear form, and some
+manufacturers prefer the latter because of the positive pumping
+features. They are very simple in form, consisting of a suitable cast
+body in which a pair of spur pinions having large teeth are carried. One
+of these gears is driven by suitable means, and as it turns the other
+member they maintain a flow of water around the pump body. The pump
+should always be installed in series with the water pipe which conveys
+the cool liquid from the lower compartment of the radiator to the
+coolest portion of the water jacket.
+
+[Illustration: Fig. 84.--Finned Tube Radiators at the Side of Hall-Scott
+Airplane Power Plant Installed in Standard Fuselage.]
+
+
+WATER CIRCULATION BY NATURAL SYSTEM
+
+Some automobile engineers contend that the rapid water circulation
+obtained by using a pump may cool the cylinders too much, and that the
+temperature of the engine may be reduced so much that the efficiency
+will be lessened. For this reason there is a growing tendency to use the
+natural method of water circulation as the cooling liquid is supplied to
+the cylinder jackets just below the boiling point and the water issues
+from the jacket at the top of the cylinder after it has absorbed
+sufficient heat to raise it just about to the boiling point.
+
+As the water becomes heated by contact with the hot cylinder and
+combustion-chamber walls it rises to the top of the water jacket, flows
+to the cooler, where enough of the heat is absorbed to cause it to
+become sensibly greater in weight. As the water becomes cooler, it falls
+to the bottom of the radiator and it is again supplied to the water
+jacket. The circulation is entirely automatic and continues as long as
+there is a difference in temperature between the liquid in the water
+spaces of the engine and that in the cooler. The circulation becomes
+brisker as the engine becomes hotter and thus the temperature of the
+cylinders is kept more nearly to a fixed point. With the thermosyphon
+system the cooling liquid is nearly always at its boiling point, whereas
+if the circulation is maintained by a pump the engine will become cooler
+at high speed and will heat up more at low speed.
+
+With the thermosyphon, or natural system of cooling, more water must be
+carried than with the pump-maintained circulation methods. The water
+spaces around the cylinders should be larger, the inlet and discharge
+water manifolds should have greater capacity, and be free from sharp
+corners which might impede the flow. The radiator must also carry more
+water than the form used in connection with the pump because of the
+brisker pump circulation which maintains the engine temperature at a
+lower point. Consideration of the above will show why the pump system is
+almost universally used in connection with airplane power plant cooling.
+
+
+DIRECT AIR-COOLING METHODS
+
+The earliest known method of cooling the cylinder of gas-engines was by
+means of a current of air passed through a jacket which confined it
+close to the cylinder walls and was used by Daimler on his first
+gas-engine. The gasoline engine of that time was not as efficient as the
+later form, and other conditions which materialized made it desirable to
+cool the engine by water. Even as gasoline engines became more and more
+perfected there has always existed a prejudice against air cooling,
+though many forms of engines have been used, both in automobile and
+aircraft applications where the air-cooling method has proven to be very
+practical.
+
+The simplest system of air cooling is that in which the cylinders are
+provided with a series of flanges which increase the effective radiating
+surface of the cylinder and directing an air-current from a fan against
+the flanges to absorb the heat. This increase in the available radiating
+surface of an air-cooled cylinder is necessary because air does not
+absorb heat as readily as water and therefore more surface must be
+provided that the excess heat be absorbed sufficiently fast to prevent
+distortion of the cylinders. Air-cooling systems are based on a law
+formulated by Newton, which is: "The rate for cooling for a body in a
+uniform current of air is directly proportional to the speed of the air
+current and the amount of radiating surface exposed to the cooling
+effect."
+
+
+AIR-COOLED ENGINE DESIGN CONSIDERATIONS
+
+[Illustration: Fig. 85.--Anzani Testing His Five-Cylinder Air Cooled
+Aviation Motor Installed in Bleriot Monoplane. Note Exposure of Flanged
+Cylinders to Propeller Slip Stream.]
+
+There are certain considerations which must be taken into account in
+designing an air-cooled engine, which are often overlooked in those
+forms cooled by water. Large valves must be provided to insure rapid
+expulsion of the flaming exhaust gas and also to admit promptly the
+fresh cool mixture from the carburetor. The valves of air-cooled engines
+are usually placed in the cylinder-head, in order to eliminate any
+pockets or sharp passages which would impede the flow of gas or retain
+some of the products of combustion and their heat. When high power is
+desired multiple-cylinder engines should be used, as there is a certain
+limit to the size of a successful air-cooled cylinder. Much better
+results are secured from those having small cubical contents because the
+heat from small quantities of gas will be more quickly carried off than
+from greater amounts. All successful engines of the aviation type which
+have been air-cooled have been of the multiple-cylinder type.
+
+An air-cooled engine must be placed in the fuselage, as at Fig. 85, in
+such a way that there will be a positive circulation of air around it
+all the time that it is in operation. The air current may be produced by
+the tractor screw at the front end of the motor, or by a suction or
+blower fan attached to the crank-shaft as in the Renault engine or by
+rotating the cylinders as in the Le Rhone and Gnome motors. Greater care
+is required in lubrication of the air-cooled cylinders and only the best
+quality of oil should be used to insure satisfactory oiling.
+
+The combustion chambers must be proportioned so that distribution of
+metal is as uniform as possible in order to prevent uneven expansion
+during increase in temperature and uneven contraction when the cylinder
+is cooled. It is essential that the inside walls of the combustion
+chamber be as smooth as possible because any sharp angle or projection
+may absorb sufficient heat to remain incandescent and cause trouble by
+igniting the mixture before the proper time. The best grades of cast
+iron or steel should be used in the cylinder and piston and the machine
+work must be done very accurately so the piston will operate with
+minimum friction in the cylinder. The cylinder bore should not exceed
+4-1/2 or 5 inches and the compression pressure should never exceed 75
+pounds absolute, or about five atmospheres, or serious overheating will
+result.
+
+As an example of the care taken in disposing of the exhaust gases in
+order to obtain practical air-cooling, some cylinders are provided with
+a series of auxiliary exhaust ports uncovered by the piston when it
+reaches the end of its power stroke. The auxiliary exhaust ports open
+just as soon as the full force of the explosion has been spent and a
+portion of the flaming gases is discharged through the ports in the
+bottom of the cylinder. Less of the exhaust gases remains to be
+discharged through the regular exhaust member in the cylinder-head and
+this will not heat the walls of the cylinder nearly as much as the
+larger quantity of hot gas would. That the auxiliary exhaust port is of
+considerable value is conceded by many designers of fixed and fan-shaped
+air-cooled motors for airplanes.
+
+Among the advantages stated for direct air cooling, the greatest is the
+elimination of cooling water and its cooling auxiliaries, which is a
+factor of some moment, as it permits considerable reduction in
+horse-power-weight ratio of the engine, something very much to be
+desired. In the temperate zone, where the majority of airplanes are
+used, the weather conditions change in a very few months from the warm
+summer to the extreme cold winter, and when water-cooled systems are
+employed it is necessary to add some chemical substance to the water to
+prevent it from freezing. The substances commonly employed are
+glycerine, wood alcohol, or a saturated solution of calcium chloride.
+Alcohol has the disadvantage in that it vaporizes readily and must be
+often renewed. Glycerine affects the rubber hose, while the calcium
+chloride solution crystallizes and deposits salt in the radiator and
+water pipes.
+
+One of the disadvantages of an air-cooling method, as stated by those
+who do not favor this system, is that engines cooled by air cannot be
+operated for extended periods under constant load or at very high speed
+without heating up to such a point that premature ignition of the charge
+may result. The water-cooling systems, at the other hand, maintain the
+temperature of the engine more nearly constant than is possible with an
+air-cooled motor, and an engine cooled by water can be operated under
+conditions of inferior lubrication or poor mixture adjustment that would
+seriously interfere with proper and efficient cooling by air.
+
+Air-cooled motors, as a rule, use less fuel than water-cooled engines,
+because the higher temperature of the cylinder does not permit of a full
+charge of gas being inspired on the intake stroke. As special care is
+needed in operating an air-cooled engine to obtain satisfactory results
+and because of the greater difficulty which obtains in providing proper
+lubrication and fuel mixtures which will not produce undue heating, the
+air-cooled system has but few adherents at the present time, and
+practically all airplanes, with but very few exceptions, are provided
+with water-cooled power plants. Those fitted with air-cooled engines are
+usually short-flight types where maximum lightness is desired in order
+to obtain high speed and quick climb. The water-cooled engines are best
+suited for airplanes intended for long flights. The Gnome, Le Rhone and
+Clerget engines are thoroughly practical and have been widely used in
+France and England. These are rotary radial cylinder types. The Anzani
+is a fixed cylinder engine used on training machines, while the Renault
+is a V-type engine made in eight- and twelve-cylinder V forms that has
+been used on reconnaissance and bombing airplanes with success. These
+types will be fully considered in proper sequence.
+
+
+
+
+CHAPTER VIII
+
+    Methods of Cylinder Construction--Block Castings--Influence on
+    Crank-Shaft Design--Combustion Chamber Design--Bore and Stroke
+    Ratio--Meaning of Piston Speed--Advantage of Off-Set Cylinders--
+    Valve Location of Vital Import--Valve Installation Practice--
+    Valve Design and Construction--Valve Operation--Methods of
+    Driving Cam-Shaft--Valve Springs--Valve Timing--Blowing Back--
+    Lead Given Exhaust Valve--Exhaust Closing, Inlet Opening--
+    Closing the Inlet Valve--Time of Ignition--How an Engine Is
+    Timed--Gnome "Monosoupape" Valve Timing--Springless Valves--Four
+    Valves per Cylinder.
+
+
+The improvements noted in the modern internal combustion motors have
+been due to many conditions. The continual experimenting by leading
+mechanical minds could have but one ultimate result. The parts of the
+engines have been lightened and strengthened, and greater power has been
+obtained without increasing piston displacement. A careful study has
+been made of the many conditions which make for efficient motor action,
+and that the main principles are well recognized by all engineers is
+well shown by the standardization of design noted in modern power
+plants. There are many different methods of applying the same principle,
+and it will be the purpose of this chapter to define the ways in which
+the construction may be changed and still achieve the same results. The
+various components may exist in many different forms, and all have their
+advantages and disadvantages. That all methods are practical is best
+shown by the large number of successful engines which use radically
+different designs.
+
+
+METHODS OF CYLINDER CONSTRUCTION
+
+One of the most important parts of the gasoline engine and one that has
+material bearing upon its efficiency is the cylinder unit. The cylinders
+may be cast individually, or in pairs, and it is possible to make all
+cylinders a unit or block casting. Some typical methods of cylinder
+construction are shown in accompanying illustrations. The appearance of
+individual cylinder castings may be ascertained by examination of the
+Hall-Scott airplane engine. Air-cooled engine cylinders are always of
+the individual pattern.
+
+Considered from a purely theoretical point of view, the individual
+cylinder casting has much in its favor. It is advanced that more uniform
+cooling is possible than where the cylinders are cast either in pairs or
+three or four in one casting. More uniform cooling insures that the
+expansion or change of form due to heating will be more equal. This is
+an important condition because the cylinder bore must remain true under
+all conditions of operation. If the heating effect is not uniform, which
+condition is liable to obtain if metal is not evenly distributed, the
+cylinder may become distorted by heat and the bore be out of truth. When
+separate cylinders are used it is possible to make a uniform water space
+and have the cooling liquid evenly distributed around the cylinder. In
+multiple cylinder castings this is not always the rule, as in many
+instances, especially in four-cylinder block motors where compactness is
+the main feature, there is but little space between the cylinders for
+the passage of water. Under such circumstances the cooling effect is not
+even, and the stresses which obtain because of unequal expansion may
+distort the cylinder to some extent. When steel cylinders are made from
+forgings, the water jackets are usually of copper or sheet steel
+attached to the forging by autogenous welding; in the case of the latter
+and, in some cases, the former may be electro-deposited on the
+cylinders.
+
+
+BLOCK CASTINGS
+
+[Illustration: Fig. 86.--Views of Four-Cylinder Duesenberg Airplane
+Engine Cylinder Block.]
+
+The advantage of casting the cylinders in blocks is that a motor may be
+much shorter than it would be if individual castings were used. It is
+admitted that when the cylinders are cast together a more compact,
+rigid, and stronger power plant is obtained than when cast separately.
+There is a disadvantage, however, in that if one cylinder becomes
+damaged it will be necessary to replace the entire unit, which means
+scrapping three good cylinders because one of the four has failed. When
+the cylinders are cast separately one need only replace the one that has
+become damaged. The casting of four cylinders in one unit is made
+possible by improved foundry methods, and when proper provision is made
+for holding the cores when the metal is poured and the cylinder casts
+are good, the construction is one of distinct merit. It is sometimes the
+case that the proportion of sound castings is less when cylinders are
+cast in block, but if the proper precautions are observed in molding and
+the proper mixtures of cast iron used, the ratio of defective castings
+is no more than when cylinders are molded individually. As an example of
+the courage of engineers in departing from old-established rules, the
+cylinder casting shown at Fig. 86 may be considered typical. This is
+used on the Duesenberg four-cylinder sixteen-valve 4-3/4" × 7" engine
+which has a piston displacement of 496 cu. in. At a speed of 2,000
+r.p.m., corresponding to a piston speed of 2,325 ft. per min., the
+engine is guaranteed to develop 125 horse-power. The weight of the model
+engine without gear reduction is 436 lbs., but a number of refinements
+have been made in the design whereby it is expected to get the weight
+down to 390 lbs. The four cylinders are cast from semi-steel in a single
+block, with integral heads. The cylinder construction is the same as
+that which has always been used by Mr. Duesenberg, inlet and exhaust
+valves being arranged horizontally opposite each other in the head.
+There are large openings in the water jacket at both sides and at the
+ends, which are closed by means of aluminum covers, water-tightness
+being secured by the use of gaskets. This results in a saving in weight
+because the aluminum covers can be made considerably lighter than it
+would be possible to cast the jacket walls, and, besides, it permits of
+obtaining a more nearly uniform thickness of cylinder wall, as the cores
+can be much better supported. The cooling water passes completely around
+each cylinder, and there is a very considerable space between the two
+central cylinders, this being made necessary in order to get the large
+bearing area desirable for the central bearing.
+
+It is common practice to cast the water jackets integral with the
+cylinders, if cast iron or aluminum is used, and this is also the most
+economical method of applying it because it gives good results in
+practice. An important detail is that the water spaces must be
+proportioned so that they are equal around the cylinders whether these
+members are cast individually, in pairs, threes or fours. When cylinders
+are cast in block form it is good practice to leave a large opening in
+the jacket wall which will assist in supporting the core and make for
+uniform water space. It will be noticed that the casting shown at Fig.
+86 has a large opening in the side of the cylinder block. These openings
+are closed after the interior of the casting is thoroughly cleaned of
+all sand, core wire, etc., by brass, cast iron or aluminum plates. These
+also have particular value in that they may be removed after the motor
+has been in use, thus permitting one to clean out the interior of the
+water jacket and dispose of the rust, sediment, and incrustation which
+are always present after the engine has been in active service for a
+time.
+
+Among the advantages claimed for the practice of casting cylinders in
+blocks may be mentioned compactness, lightness, rigidity, simplicity of
+water piping, as well as permitting the use of simple forms of inlet and
+exhaust manifolds. The light weight is not only due to the reduction of
+the cylinder mass but because the block construction permits one to
+lighten the entire motor. The fact that all cylinders are cast together
+decreases vibration, and as the construction is very rigid, disalignment
+of working parts is practically eliminated. When inlet and exhaust
+manifolds are cored in the block casting, as is sometimes the case, but
+one joint is needed on each of these instead of the multiplicity of
+joints which obtain when the cylinders are individual castings. The
+water piping is also simplified. In the case of a four-cylinder block
+motor but two pipes are used; one for the water to enter the cylinder
+jacket, the other for the cooling liquid to discharge through.
+
+
+INFLUENCE ON CRANK-SHAFT DESIGN
+
+[Illustration: Fig. 87.--Twin-Cylinder Block of Sturtevant Airplane
+Engine is Cast of Aluminum, and Has Removable Cylinder Head.]
+
+The method of casting the cylinders has a material influence on the
+design of the crank-shaft as will be shown in proper sequence. When four
+cylinders are combined in one block it is possible to use a two-bearing
+crank-shaft. Where cylinders are cast in pairs a three-bearing
+crank-shaft is commonly supplied, and when cylinders are cast as
+individual units it is thought necessary to supply a five-bearing
+crank-shaft, though sometimes shafts having but three journals are used
+successfully. Obviously the shafts must be stronger and stiffer to
+withstand the stresses imposed if two supporting bearings are used than
+if a larger number are employed. In this connection it may be stated
+that there is less difficulty in securing alignment with a lesser number
+of bearings and there is also less friction. On the other hand, the
+greater the number of points of support a crank-shaft has the lighter
+the webs can be made and still have requisite strength.
+
+
+COMBUSTION CHAMBER DESIGN
+
+[Illustration: Fig. 88.--Aluminum Cylinder Pair Casting of Thomas 150
+Horse-Power Airplane Engine is of the L Head Type.]
+
+Another point of importance in the design of the cylinder, and one which
+has considerable influence upon the power developed, is the shape of the
+combustion chamber. The endeavor of designers is to obtain maximum power
+from a cylinder of certain proportions, and the greater energy obtained
+without increasing piston displacement or fuel consumption the higher
+the efficiency of the motor. To prevent troubles due to pre-ignition it
+is necessary that the combustion chamber be made so that there will be
+no roughness, sharp corners, or edges of metal which may remain
+incandescent when heated or which will serve to collect carbon deposits
+by providing a point of anchorage. With the object of providing an
+absolutely clean combustion chamber some makers use a separable head
+unit to their twin cylinder castings, such as shown at Fig. 87 and Fig.
+88. These permit one to machine the entire interior of the cylinder and
+combustion chamber. The relation of valve location and combustion
+chamber design will be considered in proper sequence. These cylinders
+are cast of aluminum, instead of cast iron, as is customary, and are
+provided with steel or cast iron cylinder liners forced in the soft
+metal casting bores.
+
+
+BORE AND STROKE RATIO
+
+A question that has been a vexed one and which has been the subject of
+considerable controversy is the proper proportion of the bore to the
+stroke. The early gas engines had a certain well-defined bore to stroke
+ratio, as it was usual at that time to make the stroke twice as long as
+the bore was wide, but this cannot be done when high speed is desired.
+With the development of the present-day motor the stroke or piston
+travel has been gradually shortened so that the relative proportions of
+bore and stroke have become nearly equal. Of late there seems to be a
+tendency among designers to return to the proportions which formerly
+obtained, and the stroke is sometimes one and a half or one and
+three-quarter times the bore.
+
+Engines designed for high speed should have the stroke not much longer
+than the diameter of the bore. The disadvantage of short-stroke engines
+is that they will not pull well at low speeds, though they run with
+great regularity and smoothness at high velocity. The long-stroke engine
+is much superior for slow speed work, and it will pull steadily and with
+increasing power at low speed. It was formerly thought that such engines
+should never turn more than a moderate number of revolutions, in order
+not to exceed the safe piston speed of 1,000 feet per minute. This old
+theory or rule of practice has been discarded in designing high
+efficiency automobile racing and aviation engines, and piston speeds
+from 2,500 to 3,000 feet per minute are sometimes used, though the
+average is around 2,000 feet per minute. While both short- and
+long-stroke motors have their advantages, it would seem desirable to
+average between the two. That is why a proportion of four to five or six
+seems to be more general than that of four to seven or eight, which
+would be a long-stroke ratio. Careful analysis of a number of foreign
+aviation motors shows that the average stroke is about 1.2 times the
+bore dimensions, though some instances were noted where it was as high
+as 1.7 times the bore.
+
+
+MEANING OF PISTON SPEED
+
+The factor which limits the stroke and makes the speed of rotation so
+dependent upon the travel of the piston is piston speed. Lubrication is
+the main factor which determines piston speed, and the higher the rate
+of piston travel the greater care must be taken to insure proper oiling.
+Let us fully consider what is meant by piston speed.
+
+Assume that a motor has a piston travel or stroke of six inches, for the
+sake of illustration. It would take two strokes of the piston to cover
+one foot, or twelve inches, and as there are two strokes to a revolution
+it will be seen that this permits of a normal speed of 1,000 revolutions
+per minute for an engine with a six-inch stroke, if one does not exceed
+1,000 feet per minute. If the stroke was only four inches, a normal
+speed of 1,500 revolutions per minute would be possible without
+exceeding the prescribed limit. The crank-shaft of a small engine,
+having three-inch stroke, could turn at a speed of 2,000 revolutions per
+minute without danger of exceeding the safe speed limit. It will be seen
+that the longer the stroke the slower the speed of the engine, if one
+desires to keep the piston speed within the bounds as recommended, but
+modern practice allows of greatly exceeding the speeds formerly thought
+best.
+
+
+ADVANTAGES OF OFF-SET CYLINDERS
+
+[Illustration: Fig. 90.--Cross Section of Austro-Daimler Engine, Showing
+Offset Cylinder Construction. Note Applied Water Jacket and Peculiar
+Valve Action.]
+
+Another point upon which considerable difference of opinion exists
+relates to the method of placing the cylinder upon the crank-case--i.e.,
+whether its center line should be placed directly over the center of the
+crank-shaft, or to one side of center. The motor shown at Fig. 90 is an
+off-set type, in that the center line of the cylinder is a little to
+one side of the center of the crank-shaft. Diagrams are presented at
+Fig. 91 which show the advantages of off-set crank-shaft construction.
+The view at A is a section through a simple motor with the conventional
+cylinder placing, the center line of both crank-shaft and cylinder
+coinciding. The view at B shows the cylinder placed to one side of
+center so that its center line is distinct from that of the crank-shaft
+and at some distance from it. The amount of off-set allowed is a point
+of contention, the usual amount being from fifteen to twenty-five per
+cent. of the stroke. The advantages of the off-set are shown at Fig. 91,
+C. If the crank turns in direction of the arrow there is a certain
+resistance to motion which is proportional to the amount of energy
+exerted by the engine and the resistance offered by the load. There are
+two thrusts acting against the cylinder wall to be considered, that due
+to explosion or expansion of the gas, and that which resists the motion
+of the piston. These thrusts may be represented by arrows, one which
+acts directly in a vertical direction on the piston top, the other
+along a straight line through the center of the connecting rod. Between
+these two thrusts one can draw a line representing a resultant force
+which serves to bring the piston in forcible contact with one side of
+the cylinder wall, this being known as side thrust. As shown at C, the
+crank-shaft is at 90 degrees, or about one-half stroke, and the
+connecting rod is at 20 degrees angle. The shorter connecting rod would
+increase the diagonal resultant and side thrusts, while a longer one
+would reduce the angle of the connecting rod and the side thrust of the
+piston would be less. With the off-set construction, as shown at D, it
+will be noticed that with the same connecting-rod length as shown at C
+and with the crank-shaft at 90 degrees of the circle that the
+connecting-rod angle is 14 degrees and the side thrust is reduced
+proportionately.
+
+[Illustration: Fig. 91.--Diagrams Demonstrating Advantages of Offset
+Crank-Shaft Construction.]
+
+Another important advantage is that greater efficiency is obtained from
+the explosion with an off-set crank-shaft, because the crank is already
+inclined when the piston is at top center, and all the energy imparted
+to the piston by the burning mixture can be exerted directly into
+producing a useful turning effort. When a cylinder is placed directly on
+a line with the crank-shaft, as shown at A, it will be evident that some
+of the force produced by the expansion of the gas will be exerted in a
+direct line and until the crank moves the crank throw and connecting rod
+are practically a solid member. The pressure which might be employed in
+obtaining useful turning effort is wasted by causing a direct pressure
+upon the lower half of the main bearing and the upper half of the
+crank-pin bushing.
+
+Very good and easily understood illustrations showing advantages of the
+off-set construction are shown at E and F. This is a bicycle
+crank-hanger. It is advanced that the effort of the rider is not as well
+applied when the crank is at position E as when it is at position F.
+Position E corresponds to the position of the parts when the cylinder is
+placed directly over the crank-shaft center. Position F may be compared
+to the condition which is present when the off-set cylinder construction
+is used.
+
+
+VALVE LOCATION OF VITAL IMPORT
+
+It has often been said that a chain is no stronger than its weakest
+link, and this is as true of the explosive motor as it is of any other
+piece of mechanism. Many motors which appeared to be excellently
+designed and which were well constructed did not prove satisfactory
+because some minor detail or part had not been properly considered by
+the designer. A factor having material bearing upon the efficiency of
+the internal combustion motor is the location of the valves and the
+shape of the combustion chamber which is largely influenced by their
+placing. The fundamental consideration of valve design is that the gases
+be admitted and discharged from the cylinder as quickly as possible in
+order that the speed of gas flow will not be impeded and produce back
+pressure. This is imperative in obtaining satisfactory operation in any
+form of motor. If the inlet passages are constricted the cylinder will
+not fill with explosive mixture promptly, whereas if the exhaust gases
+are not fully expelled the parts of the inert products of combustion
+retained dilute the fresh charge, making it slow burning and causing
+lost power and overheating. When an engine employs water as a cooling
+medium this substance will absorb the surplus heat readily, and the
+effects of overheating are not noticed as quickly as when air-cooled
+cylinders are employed. Valve sizes have a decided bearing upon the
+speed of motors and some valve locations permit the use of larger
+members than do other positions.
+
+While piston velocity is an important factor in determinations of power
+output, it must be considered from the aspect of the wear produced upon
+the various parts of the motor. It is evident that engines which run
+very fast, especially of high power, must be under a greater strain than
+those operating at lower speeds. The valve-operating mechanism is
+especially susceptible to the influence of rapid movement, and the
+slower the engine the longer the parts will wear and the more reliable
+the valve action.
+
+[Illustration: Fig. 92.--Diagram Showing Forms of Cylinder Demanded by
+Different Valve Placings. A--T Head Type, Valves on Opposite Sides. B--L
+Head Cylinder, Valves Side by Side. C--L Head Cylinder, One Valve in
+Head, Other in Pocket. D--Inlet Valve Over Exhaust Member, Both in Side
+Pocket. E--Valve-in-the-Head Type with Vertical Valves. F--Inclined
+Valves Placed to Open Directly into Combustion Chamber.]
+
+As will be seen by reference to the accompanying illustration, Fig. 92,
+there are many ways in which valves may be placed in the cylinder. Each
+method outlined possesses some point of advantage, because all of the
+types illustrated are used by reputable automobile manufacturers. The
+method outlined at Fig. 92, A, is widely used, and because of its shape
+the cylinder is known as the "T" form. It is approved for automobile use
+for several reasons, the most important being that large valves can be
+employed and a well-balanced and symmetrical cylinder casting obtained.
+Two independent cam-shafts are needed, one operating the inlet valves,
+the other the exhaust members. The valve-operating mechanism can be very
+simple in form, consisting of a plunger actuated by the cam which
+transmits the cam motion to the valve-stem, raising the valve as the cam
+follower rides on the point of the cam. Piping may be placed without
+crowding, and larger manifolds can be fitted than in some other
+constructions. This has special value, as it permits the use of an
+adequate discharge pipe on the exhaust side with its obvious advantages.
+This method of cylinder construction is never found on airplane engines
+because it does not permit of maximum power output.
+
+On the other hand, if considered from a viewpoint of actual heat
+efficiency, it is theoretically the worst form of combustion chamber.
+This disadvantage is probably compensated for by uniformity of expansion
+of the cylinder because of balanced design. The ignition spark-plug may
+be located directly over the inlet valve in the path of the incoming
+fresh gases, and both valves may be easily removed and inspected by
+unscrewing the valve caps without taking off the manifolds.
+
+The valve installation shown at C is somewhat unusual, though it
+provides for the use of valves of large diameter. Easy charging is
+insured because of the large inlet valve directly in the top of the
+cylinder. Conditions may be reversed if necessary, and the gases
+discharged through this large valve. Both methods are used, though it
+would seem that the free exhaust provided by allowing the gases to
+escape directly from the combustion chamber through the overhead valve
+to the exhaust manifold would make for more power. The method outlined
+at Fig. 92, F and at Fig. 90 is one that has been widely employed on
+large automobile racing motors where extreme power is required, as well
+as in engines constructed for aviation service. The inclination of the
+valves permits the use of large valves, and these open directly into the
+combustion chamber. There are no pockets to retain heat or dead gas, and
+free intake and outlet of gas is obtained. This form is quite
+satisfactory from a theoretical point of view because of the almost
+ideal combustion chamber form. Some difficulty is experienced, however,
+in properly water-jacketing the valve chamber which experience has shown
+to be necessary if the engine is to have high power.
+
+The motor shown at Fig. 92, B and Fig. 88 employs cylinders of the "L"
+type. Both valves are placed in a common extension from the combustion
+chamber, and being located side by side both are actuated from a common
+cam-shaft. The inlet and exhaust pipes may be placed on the same side of
+the engine and a very compact assemblage is obtained, though this is
+optional if passages are cored in the cylinder pairs to lead the gases
+to opposite sides. The valves may be easily removed if desired, and the
+construction is fairly good from the viewpoint of both foundry man and
+machinist. The chief disadvantage is the limited area of the valves and
+the loss of heat efficiency due to the pocket. This form of combustion
+chamber, however, is more efficient than the "T" head construction,
+though with the latter the use of larger valves probably compensates for
+the greater heat loss. It has been stated as an advantage of this
+construction that both manifolds can be placed at the same side of the
+engine and a compact assembly secured. On the other hand, the
+disadvantage may be cited that in order to put both pipes on the same
+side they must be of smaller size than can be used when the valves are
+oppositely placed. The "L" form cylinder is sometimes made more
+efficient if but one valve is placed in the pocket while the other is
+placed over it. This construction is well shown at Fig. 92, D and is
+found on Anzani motors.
+
+[Illustration: Fig. 93.--Sectional View of Engine Cylinder Showing Valve
+and Cage Installation.]
+
+The method of valve application shown at Fig. 87 is an ingenious method
+of overcoming some of the disadvantages inherent with valve-in-the-head
+motors. In the first place it is possible to water-jacket the valves
+thoroughly, which is difficult to accomplish when they are mounted in
+cages. The water circulates directly around the walls of the valve
+chambers, which is superior to a construction where separate cages are
+used, as there are two thicknesses of metal with the latter, that of the
+valve-cage proper and the wall of the cylinder. The cooling medium is in
+contact only with the outer wall, and as there is always a loss of heat
+conductivity at a joint it is practically impossible to keep the
+exhaust valves and their seats at a uniform temperature. The valves may
+be of larger size without the use of pockets when seating directly in
+the head. In fact, they could be equal in diameter to almost half the
+bore of the cylinder, which provides an ideal condition of charge
+placement and exhaust. When valve grinding is necessary the entire head
+is easily removed by taking off six nuts and loosening inlet manifold
+connections, which operation would be necessary even if cages were
+employed, as in the engine shown at Fig. 93.
+
+[Illustration: Fig. 94.--Diagrams Showing How Gas Enters Cylinder
+Through Overhead Valves and Other Types. A--Tee Head Cylinder. B--L Head
+Cylinder. C--Overhead Valve.]
+
+[Illustration: Fig. 95.--Conventional Methods of Operating Internal
+Combustion Motor Valves.]
+
+At Fig. 94, A and B, a section through a typical "L"-shaped cylinder is
+depicted. It will be evident that where a pocket construction is
+employed, in addition to its faculty for absorbing heat, the passage of
+gas would be impeded. For example, the inlet gas rushing in through the
+open valve would impinge sharply upon the valve-cap or combustion head
+directly over the valve and then must turn at a sharp angle to enter the
+combustion chamber and then at another sharp angle to fill the
+cylinders. The same conditions apply to the exhaust gases, though they
+are reversed. When the valve-in-the-head type of cylinder is employed,
+as at C, the only resistance offered the gas is in the manifold. As far
+as the passage of the gases in and out of the cylinder is concerned,
+ideal conditions obtain. It is claimed that valve-in-the-head motors are
+more flexible and responsive than other forms, but the construction has
+the disadvantage in that the valves must be opened through a rather
+complicated system of push rods and rocker arms instead of the simpler
+and direct plunger which can be used with either the "T" or "L" head
+cylinders. This is clearly outlined in the illustrations at Fig. 95,
+where A shows the valve in the head-operating mechanism necessary if the
+cam-shaft is carried at the cylinder base, while B shows the most direct
+push-rod action obtained with "T" or "L" head cylinder placing.
+
+[Illustration: Fig. 96.--Examples of Direct Valve Actuation by Overhead
+Cam-Shaft. A--Mercedes. B--Hall-Scott. C--Wisconsin.]
+
+[Illustration: Fig. 97.
+
+CENSORED]
+
+[Illustration: Fig. 98.
+
+CENSORED]
+
+The objection can be easily met by carrying the cam-shaft above the
+cylinders and driving it by means of gearing. The types of engine
+cylinders using this construction are shown at Fig. 96, and it will be
+evident that a positive and direct valve action is possible by following
+the construction originated by the Mercedes (German) aviation engine
+designers and outlined at A. The other forms at B and C are very clearly
+adaptations of this design. The Hall-Scott engine at Fig. 97 is depicted
+in part section and no trouble will be experienced in understanding the
+bevel pinion and gear drive from the crank-shaft to the overhead
+cam-shaft through a vertical counter-shaft. A very direct valve action
+is used in the Duesenberg engines, one of which is shown in part section
+at Fig. 98. The valves are parallel with the piston top and are actuated
+by rocker arms, one end of which bears against the valve stem, and the
+other rides the cam-shaft.
+
+[Illustration: Fig. 99.--Sectional Views Showing Arrangement of Novel
+Concentric Valve Arrangement Devised by Panhard for Aerial Engines.]
+
+The form shown at Fig. 99 shows an ingenious application of the
+valve-in-the-head idea which permits one to obtain large valves. It has
+been used on some of the Panhard aviation engines and on the American
+Aeromarine power plants. The inlet passage is controlled by the sliding
+sleeve which is hollow and slotted so as to permit the inlet gases to
+enter the cylinder through the regular type poppet valve which seats in
+the exhaust sleeve. When the exhaust valve is operated by the tappet rod
+and rocker arm the intake valve is also carried down with it. The
+intake gas passage is closed, however, and the burned gases are
+discharged through the large annular passage surrounding the sleeve.
+When the inlet valve leaves its seat in the sleeve the passage of cool
+gas around the sleeve keeps the temperature of both valves to a low
+point and the danger of warping is minimized. A dome-shaped combustion
+chamber may be used, which is an ideal form in conserving heat
+efficiency, and as large valves may be installed the flow of both fresh
+and exhaust gases may be obtained with minimum resistance. The intake
+valve is opened by a small auxiliary rocker arm which is lifted when the
+cam follower rides into the depression in the cam by the action of the
+strong spring around the push rod. When the cam follower rides on the
+high point the exhaust sleeve is depressed from its seat against the
+cylinder. By using a cam having both positive and negative profiles, a
+single rod suffices for both valves because of its push and pull action.
+
+
+VALVE DESIGN AND CONSTRUCTION
+
+Valve dimensions are an important detail to be considered and can be
+determined by several conditions, among which may be cited method of
+installation, operating mechanism, material employed, engine speed
+desired, manner of cylinder cooling and degree of lift desired. A review
+of various methods of valve location has shown that when the valves are
+placed directly in the head we can obtain the ideal cylinder form,
+though larger valves may be used if housed in a separate pocket, as
+afforded by the "T" head construction. The method of operation has much
+to do with the size of the valves. For example, if an automatic inlet
+valve is employed it is good practice to limit the lift and obtain the
+required area of port opening by augmenting the diameter. Because of
+this a valve of the automatic type is usually made twenty per cent.
+larger than one mechanically operated. When both are actuated by cam
+mechanism, as is now common practice, they are usually made the same
+size and are interchangeable, which greatly simplifies manufacture. The
+relation of valve diameter to cylinder bore is one that has been
+discussed for some time by engineers. The writer's experience would
+indicate that they should be at least half the bore, if possible. While
+the mushroom type or poppet valve has become standard and is the most
+widely used form at the present time, there is some difference of
+opinion among designers as to the materials employed and the angle of
+the seat. Most valves have a bevel seat, though some have a flat
+seating. The flat seat valve has the distinctive advantage of providing
+a clear opening with lesser lift, this conducing to free gas flow. It
+also has value because it is silent in operation, but the disadvantage
+is present that best material and workmanship must be used in their
+construction to obtain satisfactory results. As it can be made very
+light it is particularly well adapted for use as an automatic inlet
+valve. Among other disadvantages cited is the claim that it is more
+susceptible to derangement, owing to the particles of foreign matter
+getting under the seat. With a bevel seat it is argued that the foreign
+matter would be more easily dislodged by the gas flow, and that the
+valve would close tighter because it is drawn positively against the
+bevel seat.
+
+Several methods of valve construction are the vogue, the most popular
+form being the one-piece type; those which are composed of a head of one
+material and stem of another are seldom used in airplane engines because
+they are not reliable. In the built-up construction the head is usually
+of high nickel steel or cast iron, which metals possess good
+heat-resisting qualities. Heads made of these materials are not likely
+to warp, scale, or pit, as is sometimes the case when ordinary grades of
+machinery steel are used. The cast-iron head construction is not popular
+because it is often difficult to keep the head tight on the stem. There
+is a slight difference in expansion ratio between the head and the stem,
+and as the stem is either screwed or riveted to the cast-iron head the
+constant hammering of the valve against its seat may loosen the joint.
+As soon as the head is loose on the stem the action of the valve becomes
+erratic. The best practice is to machine the valves from tungsten steel
+forgings. This material has splendid heat-resisting qualities and will
+not pit or become scored easily. Even the electrically welded head to
+stem types which are used in automobile engines are not looked upon with
+favor in the aviation engine. Valve stem guides and valve stems must be
+machined very accurately to insure correct action. The usual practice in
+automobile engines is shown at Fig. 100.
+
+[Illustration: Fig. 100.--Showing Clearance Allowed Between Valve Stem
+and Valve Stem Guide to Secure Free Action.]
+
+
+VALVE OPERATION
+
+The methods of valve operation commonly used vary according to the type
+of cylinder construction employed. In all cases the valves are lifted
+from their seats by cam-actuated mechanism. Various forms of
+valve-lifting cams are shown at Fig. 101. As will be seen, a cam
+consists of a circle to which a raised, approximately triangular member
+has been added at one point. When the cam follower rides on the circle,
+as shown at Fig. 102, there is no difference in height between the cam
+center and its periphery and there is no movement of the plunger. As
+soon as the raised portion of the cam strikes the plunger it will lift
+it, and this reciprocating movement is transmitted to the valve stem by
+suitable mechanical connections.
+
+[Illustration: Fig. 101.--Forms of Valve-Lifting Cams Generally
+Employed. A--Cam Profile for Long Dwell and Quick Lift. B--Typical Inlet
+Cam Used with Mushroom Type Follower. C--Average Form of Cam.
+D--Designed to Give Quick Lift and Gradual Closing.]
+
+The cam forms outlined at Fig. 101 are those commonly used. That at A is
+used on engines where it is desired to obtain a quick lift and to keep
+the valve fully opened as long as possible. It is a noisy form, however,
+and is not very widely employed. That at B is utilized more often as an
+inlet cam while the profile shown at C is generally depended on to
+operate exhaust valves. The cam shown at D is a composite form which has
+some of the features of the other three types. It will give the quick
+opening of form A, the gradual closing of form B, and the time of
+maximum valve opening provided by cam profile C.
+
+[Illustration: Fig. 102.--Showing Principal Types of Cam Followers which
+Have Received General Application.]
+
+The various types of valve plungers used are shown at Fig. 102. That
+shown at A is the simplest form, consisting of a simple cylindrical
+member having a rounded end which follows the cam profile. These are
+sometimes made of square stock or kept from rotating by means of a key
+or pin. A line contact is possible when the plunger is kept from
+turning, whereas but a single point bearing is obtained when the plunger
+is cylindrical and free to revolve. The plunger shown at A will follow
+only cam profiles which have gradual lifts. The plunger shown at B is
+left free to revolve in the guide bushing and is provided with a flat
+mushroom head which serves as a cam follower. The type shown at C
+carries a roller at its lower end and may follow very irregular cam
+profiles if abrupt lifts are desired. While forms A and B are the
+simplest, that outlined at C in its various forms is more widely used.
+Compound plungers are used on the Curtiss OX-2 motors, one inside the
+other. The small or inner one works on a cam of conventional design, the
+outer plunger follows a profile having a flat spot to permit of a pull
+rod action instead of a push rod action. All the methods in which levers
+are used to operate valves are more or less noisy because clearance must
+be left between the valve stem and the stop of the plunger. The space
+must be taken up before the valve will leave its seat, and when the
+engine is operated at high speeds the forcible contact between the
+plunger and valve stem produces a rattling sound until the valves become
+heated and expand and the stems lengthen out. Clearance must be left
+between the valve stems and actuating means. This clearance is clearly
+shown in Fig. 103 and should be .020" (twenty thousandths) when engine
+is cold. The amount of clearance allowed depends entirely upon the
+design of the engine and length of valve stem. On the Curtiss OX-2
+engines the clearance is but .010" (ten thousandths) because the valve
+stems are shorter. Too little clearance will result in loss of power or
+misfiring when engine is hot. Too much clearance will not allow the
+valve to open its full amount and will disturb the timing.
+
+[Illustration: Fig. 103.--Diagram Showing Proper Clearance to Allow
+Between Adjusting Screw and Valve Stems in Hall-Scott Aviation Engines.]
+
+
+METHODS OF DRIVING CAM-SHAFT
+
+Two systems of cam-shaft operation are used. The most common of these is
+by means of gearing of some form. If the cam-shaft is at right angles to
+the crank-shaft it may be driven by worm, spiral, or bevel gearing. If
+the cam-shaft is parallel to the crank-shaft, simple spur gear or chain
+connection may be used to turn it. A typical cam-shaft for an
+eight-cylinder V engine is shown at Fig. 104. It will be seen that the
+sixteen cams are forged integrally with the shaft and that it is
+spur-gear driven. The cam-shaft drive of the Hall-Scott motor is shown
+at Fig. 97.
+
+[Illustration: Fig. 104.--Cam-Shaft of Thomas Airplane Motor Has Cams
+Forged Integral. Note Split Cam-Shaft Bearings and Method of Gear
+Retention.]
+
+While gearing is more commonly used, considerable attention has been
+directed of late to silent chains for cam-shaft operation. The ordinary
+forms of block or roller chain have not proven successful in this
+application, but the silent chain, which is in reality a link belt
+operating over toothed pulleys, has demonstrated its worth. The tendency
+to its use is more noted on foreign motors than those of American
+design. It first came to public notice when employed on the
+Daimler-Knight engine for driving the small auxiliary crank-shafts which
+reciprocated the sleeve valves. The advantages cited for the application
+of chains are, first, silent operation, which obtains even after the
+chains have worn considerably; second, in designing it is not necessary
+to figure on maintaining certain absolute center distances between the
+crank-shaft and cam-shaft sprockets, as would be the case if
+conventional forms of gearing were used. On some forms of motor
+employing gears, three and even four members are needed to turn the
+cam-shaft. With a chain drive but two sprockets are necessary, the chain
+forming a flexible connection which permits the driving and driven
+members to be placed at any distance apart that the exigencies of the
+design demand. When chains are used it is advised that some means for
+compensating chain slack be provided, or the valve timing will lag when
+chains are worn. Many combination drives may be worked out with chains
+that would not be possible with other forms of gearing. Direct gear
+drive is favored at the present time by airplane engine designers
+because they are the most certain and positive means, even when a number
+of gears must be used as intermediate drive members. With overhead
+cam-shafts, bevel gears work out very well in practice, as in the
+Hall-Scott motors and others of that type.
+
+
+VALVE SPRINGS
+
+[Illustration: Fig. 105.--Section Through Cylinder of Knight Motor,
+Showing Important Parts of Valve Motion.]
+
+Another consideration of importance is the use of proper valve-springs,
+and particular care should be taken with those, of automatic valves. The
+spring must be weak enough to allow the valve to open when the suction
+is light, and must be of sufficient strength to close it in time at high
+speeds. It should be made as large as possible in diameter and with a
+large number of convolutions, in order that fatigue of the metal be
+obviated, and it is imperative that all springs be of the same strength
+when used on a multiple-cylinder engine. Practically all valves used to
+control the gas flow in airplane engines are mechanically operated. On
+the exhaust valve the spring must be strong enough so that the valve
+will not be sucked in on the inlet stroke. It should be borne in mind
+that if the spring is too strong a strain will be imposed on the
+valve-operating mechanism, and a hammering action produced which may
+cause deformation of the valve-seat. Only pressure enough to insure that
+the operating mechanism will follow the cam is required. It is common
+practice to make the inlet and exhaust valve springs of the same
+tension when the valves are of the same size and both mechanically
+operated. This is done merely to simplify manufacture and not because it
+is necessary for the inlet valve-spring to be as strong as the other.
+Valve springs of the helical coil type are generally used, though
+torsion or "scissors" springs and laminated or single-leaf springs are
+also utilized in special applications. Two springs are used on each
+valve in some valve-in-the-head types; a spring of small pitch diameter
+inside the regular valve-spring and concentric with it. Its function is
+to keep the valve from falling into the cylinder in event of breakage of
+the main spring in some cases, and to provide a stronger return action
+in others.
+
+[Illustration: Fig. 106.--Diagrams Showing Knight Sleeve Valve Action.]
+
+
+KNIGHT SLIDE VALVE MOTOR
+
+The sectional view through the cylinder at Fig. 105 shows the Knight
+sliding sleeves and their actuating means very clearly. The diagrams at
+Fig. 106 show graphically the sleeve movements and their relation to the
+crank-shaft and piston travel. The action may be summed up as follows:
+The inlet port begins to open when the lower edge of the opening of the
+outside sleeve which is moving down passes the top of the slot in the
+inner member also moving downwardly. The inlet port is closed when the
+lower edge of the slot in the inner sleeve which is moving up passes the
+top edge of the port in the outer sleeve which is also moving toward the
+top of the cylinder. The inlet opening extends over two hundred degrees
+of crank motion. The exhaust port is uncovered slightly when the lower
+edge of the port in the inner sleeve which is moving down passes the
+lower edge of the portion of the cylinder head which protrudes in the
+cylinder. When the top of the port in the outer sleeve traveling toward
+the bottom of the cylinder passes the lower edge of the slot in the
+cylinder wall the exhaust passage is closed. The exhaust opening extends
+over a period corresponding to about two hundred and forty degrees of
+crank motion. The Knight motor has not been applied to aircraft to the
+writer's knowledge, but an eight-cylinder Vee design that might be
+useful in that connection if lightened is shown at Fig. 107. The main
+object is to show that the Knight valve action is the only other besides
+the mushroom or poppet valve that has been applied successfully to high
+speed gasoline engines.
+
+
+VALVE TIMING
+
+It is in valve timing that the greatest difference of opinion prevails
+among engineers, and it is rare that one will see the same formula in
+different motors. It is true that the same timing could not be used with
+motors of different construction, as there are many factors which
+determine the amount of lead to be given to the valves. The most
+important of these is the relative size of the valve to the cylinder
+bore, the speed of rotation it is desired to obtain, the fuel
+efficiency, the location of the valves, and other factors too numerous
+to mention.
+
+[Illustration: Fig. 107.--Cross Sectional View of Knight Type Eight
+Cylinder V Engine.]
+
+Most of the readers should be familiar with the cycle of operation of
+the internal combustion motor of the four-stroke type, and it seems
+unnecessary to go into detail except to present a review. The first
+stroke of the piston is one in which a charge of gas is taken into the
+motor; the second stroke, which is in reverse direction to the first, is
+a compression stroke, at the end of which the spark takes place,
+exploding the charge and driving the piston down on the third or
+expansion stroke, which is in the same direction as the intake stroke,
+and finally, after the piston has nearly reached the end of this stroke,
+another valve opens to allow the burned gases to escape, and remains
+open until the piston has reached the end of the fourth stroke and is in
+a position to begin the series over again. The ends of the strokes are
+reached when the piston comes to a stop at either top or bottom of the
+cylinder and reverses its motion. That point is known as a center, and
+there are two for each cylinder, top and bottom centers, respectively.
+
+All circles may be divided into 360 parts, each of which is known as a
+degree, and, in turn, each of these degrees may be again divided into
+minutes and seconds, though we need not concern ourselves with anything
+less than the degree. Each stroke of the piston represents 180 degrees
+travel of the crank, because two strokes represent one complete
+revolution of three hundred and sixty degrees. The top and bottom
+centers are therefore separated by 180 degrees. Theoretically each phase
+of a four-cycle engine begins and ends at a center, though in actual
+practice the inertia or movement of the gases makes it necessary to
+allow a lead or lag to the valve, as the case may be. If a valve opens
+before a center, the distance is called "lead"; if it closes after a
+center, this distance is known as "lag." The profile of the cams
+ordinarily used to open or close the valves represents a considerable
+time in relation to the 180 degrees of the crank-shaft travel, and the
+area of the passages through which the gases are admitted or exhausted
+is quite small owing to the necessity of having to open or close the
+valves at stated times; therefore, to open an adequately large passage
+for the gases it is necessary to open the valves earlier and close them
+later than at centers.
+
+That advancing the opening of the exhaust valve was of value was
+discovered on the early motors and is explained by the necessity of
+releasing a large amount of gas, the volume of which has been greatly
+raised by the heat of combustion. When the inlet valves were
+mechanically operated it was found that allowing them to lag at closing
+enabled the inspiration of a greater volume of gas. Disregarding the
+inertia or flow of the gases, opening the exhaust at center would enable
+one to obtain full value of the expanding gases the entire length of the
+piston stroke, and it would not be necessary to keep the valve open
+after the top center, as the reverse stroke would produce a suction
+effect which might draw some of the inert charge back into the cylinder.
+On the other hand, giving full consideration to the inertia of the gas,
+opening the valve before center is reached will provide for quick
+expulsion of the gases, which have sufficient velocity at the end of the
+stroke, so that if the valve is allowed to remain open a little longer,
+the amount of lag varying with the opinions of the designer, the
+cylinder is cleared in a more thorough manner.
+
+
+BLOWING BACK
+
+When the factor of retarded opening is considered without reckoning the
+inertia of the gases, it would appear that if the valve were allowed to
+remain open after center had passed, say, on the closing of the inlet,
+the piston, having reversed its motion, would have the effect of
+expelling part of the fresh charge through the still open valve as it
+passed inward at its compression stroke. This effect is called blowing
+back, and is often noted with motors where the valve settings are not
+absolutely correct, or where the valve-springs or seats are defective
+and prevent proper closing.
+
+This factor is not of as much import as might appear, as on closer
+consideration it will be seen that the movement of the piston as the
+crank reaches either end of the stroke is less per degree of angular
+movement than it is when the angle of the connecting rod is greater.
+Then, again, a certain length of time is required for the reversal of
+motion of the piston, during which time the crank is in motion but the
+piston practically at a standstill. If the valves are allowed to remain
+open during this period, the passage of the gas in or out of the
+cylinder will be by its own momentum.
+
+
+LEAD GIVEN EXHAUST VALVE
+
+The faster a motor turns, all other things being equal, the greater the
+amount of lead or advance it is necessary to give the opening of the
+exhaust valve. It is self-evident truth that if the speed of a motor is
+doubled it travels twice as many degrees in the time necessary to lower
+the pressure. As most designers are cognizant of this fact, the valves
+are proportioned accordingly. It is well to consider in this respect
+that the cam profile has much to do with the manner in which the valve
+is opened; that is, the lift may be abrupt and the gas allowed to escape
+in a body, or the opening may be gradual, the gas issuing from the
+cylinder in thin streams. An analogy may be made with the opening of any
+bottle which contains liquid highly carbonated. If the cork is removed
+suddenly the gas escapes with a loud pop, but, on the other hand, if the
+bottle is uncorked gradually, the gas escapes from the receptacle in
+thin streams around the cork, and passage of the gases to the air is
+accomplished without noise. While the second plan is not harsh, it is
+slower than the former, as must be evident.
+
+
+EXHAUST CLOSING, INLET OPENING
+
+A point which has been much discussed by engineers is the proper
+relation of the closing of the exhaust valve and the opening of the
+inlet. Theoretically they should succeed each other, the exhaust closing
+at upper dead center and the inlet opening immediately afterward. The
+reason why a certain amount of lag is given the exhaust closing in
+practice is that the piston cannot drive the gases out of the cylinder
+unless they are compressed to a degree in excess of that existing in the
+manifold or passages, and while toward the end of the stroke this
+pressure may be feeble, it is nevertheless indispensable. At the end of
+the piston's stroke, as marked by the upper dead center, this
+compression still exists, no matter how little it may be, so that if the
+exhaust valve is closed and the inlet opened immediately afterward, the
+pressure which exists in the cylinder may retard the entrance of the
+fresh gas and a certain portion of the inert gas may penetrate into the
+manifold. As the piston immediately begins to aspirate, this may not be
+serious, but as these gases are drawn back into the cylinder the fresh
+charge will be diluted and weakened in value. If the spark-plug is in a
+pocket, the points may be surrounded by this weak gas, and the explosion
+will not be nearly as energetic as when the ignition spark takes place
+in pure mixture.
+
+It is a well-known fact that the exhaust valve should close after dead
+center and that a certain amount of lag should be given to opening of
+the inlet. The lag given the closing of the exhaust valve should not be
+as great as that given the closing of the inlet valve. Assuming that the
+excess pressure of the exhaust will equal the depression during
+aspiration, the time necessary to complete the emptying of the cylinder
+will be proportional to the volume of the gas within it. At the end of
+the suction stroke the volume of gas contained in the cylinder is equal
+to the cylindrical volume plus the space of the combustion chamber. At
+the end of the exhaust stroke the volume is but that of the dead space,
+and from one-third to one-fifth its volume before compression. While it
+is natural to assume that this excess of burned gas will escape faster
+than the fresh gas will enter the cylinder, it will be seen that if the
+inlet valve were allowed to lag twenty degrees, the exhaust valve lag
+need not be more than five degrees, providing that the capacity of the
+combustion chamber was such that the gases occupied one-quarter of their
+former volume.
+
+It is evident that no absolute rule can be given, as back pressure will
+vary with the design of the valve passages, the manifolds, and the
+construction of the muffler. The more direct the opening, the sooner the
+valve can be closed and the better the cylinder cleared. Ten degrees
+represent an appreciable angle of the crank, and the time required for
+the crank to cover this angular motion is not inconsiderable and an
+important quantity of the exhaust may escape, but the piston is very
+close to the dead center after the distance has been covered.
+
+Before the inlet valve opens there should be a certain depression in the
+cylinder, and considerable lag may be allowed before the depression is
+appreciable. So far as the volume of fresh gas introduced during the
+admission stroke is concerned, this is determined by the displacement of
+the piston between the point where the inlet valve opens and the point
+of closing, assuming that sufficient gas has been inspired so that an
+equilibrium of pressure has been established between the interior of the
+cylinder and the outer air. The point of inlet opening varies with
+different motors. It would appear that a fair amount of lag would be
+fifteen degrees past top center for the inlet opening, as a certain
+depression will exist in the cylinder, assuming that the exhaust valve
+has closed five or ten degrees after center, and at the same time the
+piston has not gone down far enough on its stroke to materially decrease
+the amount of gas which will be taken into the cylinder.
+
+
+CLOSING THE INLET VALVE
+
+As in the case with the other points of opening and closing, there is a
+wide diversity of practice as relates to closing the inlet valve. Some
+of the designers close this exactly at bottom center, but this practice
+cannot be commended, as there is a considerable portion of time, at
+least ten or fifteen degrees angular motion of the crank, before the
+piston will commence to travel to any extent on its compression stroke.
+The gases rushing into the cylinder have considerable velocity, and
+unless an equilibrium is obtained between the pressure inside and that
+of the atmosphere outside, they will continue to rush into the cylinder
+even after the piston ceases to exert any suction effect.
+
+For this reason, if the valve is closed exactly on center, a full charge
+may not be inspired into the cylinder, though if the time of closing is
+delayed, this momentum or inertia of the gas will be enough to insure
+that a maximum charge is taken into the cylinder. The writer considers
+that nothing will be gained if the valve is allowed to remain open
+longer than twenty degrees, and an analysis of practice in this respect
+would seem to confirm this opinion. From that point in the crank
+movement the piston travel increases and the compressive effect is
+appreciable, and it would appear that a considerable proportion of the
+charge might be exhausted into the manifold and carburetor if the valve
+were allowed to remain open beyond a point corresponding to twenty
+degrees angular movement of the crank.
+
+
+TIME OF IGNITION
+
+In this country engineers unite in providing a variable time of
+ignition, though abroad some difference of opinion is noted on this
+point. The practice of advancing the time of ignition, when affected
+electrically, was severely condemned by early makers, these maintaining
+that it was necessary because of insufficient heat and volume of the
+spark, and it was thought that advancing ignition was injurious. The
+engineers of to-day appreciate the fact that the heat of the electric
+spark, especially when from a mechanical generator of electrical energy,
+is the only means by which we can obtain practically instantaneous
+explosion, as required by the operation of motors at high speeds, and
+for the combustion of large volumes of gas.
+
+[Illustration: Fig. 108.--Diagrams Explaining Valve and Ignition Timing
+of Hall-Scott Aviation Engine.]
+
+It is apparent that a motor with a fixed point of ignition is not as
+desirable, in every way, as one in which the ignition can be advanced to
+best meet different requirements, and the writer does not readily
+perceive any advantage outside of simplicity of control in establishing
+a fixed point of ignition. In fact, there seems to be some difference of
+opinion among those designers who favor fixed ignition, and in one case
+this is located forty-three degrees ahead of center, and in another
+motor the point is fixed at twenty degrees, so that it may be said that
+this will vary as much as one hundred per cent. in various forms. This
+point will vary with different methods of ignition, as well as the
+location of the spark-plug or igniter. For the sake of simplicity, most
+airplane engines use set spark; if an advancing and retarding mechanism
+is fitted, it is only to facilitate starting, as the spark is kept
+advanced while in flight, and control is by throttle alone.
+
+[Illustration: Fig. 109.--Timing Diagram of Typical Six-Cylinder
+Engine.]
+
+It is obvious by consideration of the foregoing that there can be no
+arbitrary rules established for timing, because of the many conditions
+which determine the best times for opening and closing the valves. It is
+customary to try various settings when a new motor is designed until the
+most satisfactory points are determined, and the setting which will be
+very suitable for one motor is not always right for one of different
+design. The timing diagram shown at Fig. 108 applies to the Hall-Scott
+engine, and may be considered typical. It should be easily followed in
+view of the very complete explanation given in preceding pages. Another
+six-cylinder engine diagram is shown at Fig. 109, and an eight-cylinder
+timing diagram is shown at Fig. 110. In timing automobile engines no
+trouble is experienced, because timing marks are always indicated on
+the engine fly-wheel register with an indicating trammel on the
+crank-case. To time an airplane engine accurately, as is necessary to
+test for a suspected cam-shaft defect, a timing disc of aluminum is
+attached to the crank-shaft which has the timing marks indicated
+thereon. If the disc is made 10 or 12 inches in diameter, it may be
+divided into degrees without difficulty.
+
+[Illustration: Fig. 110.--Timing Diagram of Typical Eight-Cylinder V
+Engine.]
+
+
+HOW AN ENGINE IS TIMED
+
+In timing a motor from the marks on the timing disc rim it is necessary
+to regulate the valves of but one cylinder at a time. Assuming that the
+disc is revolving in the direction of engine rotation, and that the
+firing order of the cylinders is 1-3-4-2, the operation of timing would
+be carried on as follows: The crank-shaft would be revolved until the
+line marked "Exhaust opens 1 and 4" registered with the trammel on the
+motor bed. At this point the exhaust-valve of either cylinder No. 1 or
+No. 4 should begin to open. This can be easily determined by noting
+which of these cylinders holds the compressed charge ready for ignition.
+Assuming that the spark has occurred in cylinder No. 1, then when the
+fly-wheel is turned from the position to that in which the line marked
+"Exhaust opens 1 and 4" coincides with the trammel point, the
+valve-plunger under the exhaust-valve of cylinder No. 1 should be
+adjusted in such a way that there is no clearance between it and the
+valve stem. Further movement of the wheel in the same direction should
+produce a lift of the exhaust valve. The disc is turned about two
+hundred and twenty-five degrees, or a little less than three-quarters of
+a revolution; then the line marked "Exhaust closes 1 and 4" will
+register with the trammel point. At this period the valve-plunger and
+the valve-stem should separate and a certain amount of clearance obtain
+between them. The next cylinder to time would be No. 3. The crank-shaft
+is rotated until mark "Exhaust opens 2 and 3" comes in line with the
+trammel. At this point the exhaust valve of cylinder No. 3 should be
+just about opening. The closing is determined by rotating the shaft
+until the line "Exhaust closes 2 and 3" comes under the trammel.
+
+This operation is carried on with all the cylinders, it being well to
+remember that but one cylinder is working at a time and that a
+half-revolution of the fly-wheel corresponds to a full working stroke of
+all the cylinders, and that while one is exhausting the others are
+respectively taking in a new charge, compressing and exploding. For
+instance, if cylinder No. 1 has just completed its power-stroke, the
+piston in cylinder No. 3 has reached the point where the gas may be
+ignited to advantage. The piston of cylinder No. 4, which is next to
+fire, is at the bottom of its stroke and will have inspired a charge,
+while cylinder No. 2, which is the last to fire, will have just finished
+expelling a charge of burned gas, and will be starting the intake
+stroke. This timing relates to a four-cylinder engine in order to
+simplify the explanation. The timing instructions given apply only to
+the conventional motor types. Rotary cylinder engines, especially the
+Gnome "monosoupape," have a distinctive valve timing on account of the
+peculiarities of design.
+
+
+GNOME "MONOSOUPAPE" VALVE TIMING
+
+In the present design of the Gnome motor, a cycle of operations somewhat
+different from that employed in the ordinary four-cycle engine is made
+use of, says a writer in "The Automobile," in describing the action of
+this power-plant. This cycle does away with the need for the usual inlet
+valve and makes the engine operable with only a single valve, hence the
+name _monosoupape_, or "single-valve." The cycle is as follows: A charge
+being compressed in the outer end of the cylinder or combustion chamber,
+it is ignited by a spark produced by the spark-plug located in the side
+of this chamber, and the burning charge expands as the piston moves down
+in the cylinder while the latter revolves around the crank-shaft. When
+the piston is about half-way down on the power stroke, the exhaust
+valve, which is located in the center of the cylinder-head, is
+mechanically opened, and during the following upstroke of the piston the
+burnt gases are expelled from the cylinder through the exhaust valve
+directly into the atmosphere.
+
+Instead of closing at the end of the exhaust stroke, or a few degrees
+thereafter, the exhaust valve is held open for about two-thirds of the
+following inlet stroke of the piston, with the result that fresh air is
+drawn through the exhaust valve into the cylinder. When the cylinder is
+still 65 degrees from the end of the inlet half-revolution, the exhaust
+valve closes. As no more air can get into the cylinder, and as the
+piston continues to move inwardly, it is obvious that a partial vacuum
+is formed.
+
+When the cylinder approaches within 20 degrees of the end of the inlet
+half-revolution a series of small inlet ports all around the
+circumference of the cylinder wall is uncovered by the top edge of the
+piston, whereby the combustion chamber is placed in communication with
+the crank chamber. As the pressure in the crank chamber is substantially
+atmospheric and that in the combustion chamber is below atmospheric,
+there results a suction effect which causes the air from the crank
+chamber to flow into the combustion chamber. The air in the crank
+chamber is heavily charged with gasoline vapor, which is due to the fact
+that a spray nozzle connected with the gasoline supply tank is located
+inside the chamber. The proportion of gasoline vapor in the air in the
+crank chamber is several times as great as in the ordinary combustible
+mixture drawn from a carburetor into the cylinder. This extra-rich
+mixture is diluted in the combustion chamber with the air which entered
+it through the exhaust valve during the first part of the inlet stroke,
+thus forming a mixture of the proper proportion for complete combustion.
+
+The inlet ports in the cylinder wall remain open until 20 degrees of
+the compression half-revolution has been completed, and from that moment
+to near the end of the compression stroke the gases are compressed in
+the cylinder. Near the end of the stroke ignition takes place and this
+completes the cycle.
+
+The exact timing of the different phases of the cycle is shown in the
+diagram at Fig. 111. It will be seen that ignition occurs substantially
+20 degrees ahead of the outer dead center, and expansion of the burning
+gases continues until 85 degrees past the outer dead center, when the
+piston is a little past half-stroke. Then the exhaust-valve opens and
+remains open for somewhat more than a complete revolution of the
+cylinders, or, to be exact, for 390 degrees of cylinder travel, until
+115 degrees past the top dead center on the second revolution. Then for
+45 degrees of travel the charge within the cylinder is expanded,
+whereupon the inlet ports are uncovered and remain open for 40 degrees
+of cylinder travel, 20 degrees on each side of the inward dead center
+position.
+
+
+SPRINGLESS VALVES
+
+Springless valves are the latest development on French racing car
+engines, and it is possible that the positively-operated types will be
+introduced on aviation engines also. Two makes of positively-actuated
+valves are shown at Fig. 112. The positive-valve motor differs from the
+conventional form by having no necessity for valve-springs, as a cam not
+only assures the opening of the valve, but also causes it to return to
+the valve-seat. In this respect it is much like the sleeve-valve motor,
+where the uncovering of the ports is absolutely positive. The cars
+equipped with these valves were a success in long-distance auto races.
+Claims made for this type of valve mechanism include the possibility of
+a higher number of revolutions and consequently greater engine power.
+With the spring-controlled, single-cam operated valve a point is reached
+where the spring is not capable of returning the valve to its seat
+before the cam has again begun its opening movement. It is possible to
+extend the limits considerably by using a light valve on a strong
+spring, but the valve still remains a limiting factor in the speed of
+the motor.
+
+[Illustration: Fig. 111.--Timing Diagram Showing Peculiar Valve Timing
+of Gnome "Monosoupape" Rotary Motor.]
+
+A part sectional view through a cylinder of an engine designed by G.
+Michaux is shown at Fig. 112, A. There are two valves per cylinder,
+inclined at about ten degrees from the vertical. The valve-stems are of
+large diameter, as owing to positive control, there is no necessity of
+lightening this part in an unusual degree. A single overhead cam-shaft
+has eight pairs of cams, which are shown in detail at B. For each valve
+there is a three-armed rocker, one arm of which is connected to the stem
+of the valve and the two others are in contact respectively with the
+opening and closing cams. The connection to the end of the valve-stem is
+made by a short connecting link, which is screwed on to the end of the
+valve-stem and locked in position. This allows some adjustment to be
+made between the valves and the actuating rocker. It will be evident
+that one cam and one rocker arm produce the opening of the valve and
+that the corresponding rocker arm and cam result in the closing of the
+valve. If the opening cam has the usual convex profile, the closing cam
+has a correspondingly concave profile. It will be noticed that a light
+valve-spring is shown in drawing. This is provided to give a final
+seating to its valve after it has been closed by the cam. This is not
+absolutely necessary, as an engine has been run successfully without
+these springs. The whole mechanism is contained within an overhead
+aluminum cover.
+
+[Illustration: Fig. 112.--Two Methods of Operating Valves by Positive
+Cam Mechanism Which Closes as Well as Opens Them.]
+
+The positive-valve system used on the De Lage motor is shown at D. In
+this the valves are actuated as shown in sectional views D and E. The
+valve system is unique in that four valves are provided per cylinder,
+two for exhaust and two for intake. The valves are mounted side by side,
+as shown at E, so the double actuator member may be operated by a single
+set of cams. The valve-operating member consists of a yoke having guide
+bars at the top and bottom. The actuating cam works inside of this yoke.
+The usual form of cam acts on the lower portion of the yoke to open the
+valve, while the concave cam acts on the upper part to close the valves.
+In this design provision is made for expansion of the valve-stems due to
+heat, and these are not positively connected to the actuating member. As
+shown at E, the valves are held against the seat by short coil springs
+at the upper end of the stem. These are very stiff and are only intended
+to provide for expansion. A slight space is left between the top of the
+valve-stem and the portion of the operating member that bears against
+them when the regular profile cam exerts its pressure on the bottom of
+the valve-operating mechanism. Another novelty in this motor design is
+that the cam-shafts and the valve-operating members are carried in
+casing attached above the motor by housing supports in the form of small
+steel pillars. The overhead cam-shafts are operated by means of bevel
+gearing.
+
+
+FOUR VALVES PER CYLINDER
+
+[Illustration: Fig. 113.--Diagram Comparing Two Large Valves and Four
+Small Ones of Practically the Same Area. Note How Easily Small Valves
+are Installed to Open Directly Into the Cylinder.]
+
+Mention has been previously made of the sixteen-valve four-cylinder
+Duesenberg motor and its great power output for the piston displacement.
+This is made possible by the superior volumetric efficiency of a motor
+provided with four valves in each cylinder instead of but two. This
+principle was thoroughly tried out in racing automobile motors, and is
+especially valuable in permitting of greater speed and power output from
+simple four- and six-cylinder engines. On eight- and twelve-cylinder
+types, it is doubtful if the resulting complication due to using a very
+large number of valves would be worth while. When extremely large valves
+are used, as shown in diagram at Fig. 113, it is difficult to have them
+open directly into the cylinder, and pockets are sometimes necessary. A
+large valve would weigh more than two smaller valves having an area
+slightly larger in the aggregate; it would require a stiffer valve
+spring on account of its greater weight. A certain amount of metal in
+the valve-head is necessary to prevent warping; therefore, the inertia
+forces will be greater in the large valve than in the two smaller
+valves. As a greater port area is obtained by the use of two valves,
+the gases will be drawn into the cylinder or expelled faster than with a
+lesser area. Even if the areas are practically the same as in the
+diagram at Fig. 113, the smaller valves may have a greater lift without
+imposing greater stresses on the valve-operating mechanism and quicker
+gas intake and exhaust obtained. The smaller valves are not affected by
+heat as much as larger ones are. The quicker gas movements made
+possible, as well as reduction of inertia forces, permits of higher
+rotative speed, and, consequently, greater power output for a given
+piston displacement. The drawings at Fig. 114 show a sixteen-valve motor
+of the four-cylinder type that has been designed for automobile racing
+purposes, and it is apparent that very slight modifications would make
+it suitable for aviation purposes. Part of the efficiency is due to the
+reduction of bearing friction by the use of ball bearings, but the
+multiple-valve feature is primarily responsible for the excellent
+performance.
+
+[Illustration: Fig. 114.--Sectional Views of Sixteen-Valve Four-Cylinder
+Automobile Racing Engine That May Have Possibilities for Aviation
+Service.]
+
+[Illustration: Fig. 115.--Front View of Curtiss OX-3 Aviation Motor,
+Showing Unconventional Valve Action by Concentric Push Rod and Pull
+Tube.]
+
+
+
+
+CHAPTER IX
+
+    Constructional Details of Pistons--Aluminum Cylinders and
+    Pistons--Piston Ring Construction--Leak Proof Piston Rings--
+    Keeping Oil Out of Combustion Chamber--Connecting Rod Forms--
+    Connecting Rods for Vee Engines--Cam-Shaft and Crank-Shaft
+    Designs--Ball Bearing Crank-Shafts--Engine Base Construction.
+
+
+CONSTRUCTIONAL DETAILS OF PISTONS
+
+The piston is one of the most important parts of the gasoline motor
+inasmuch as it is the reciprocating member that receives the impact of
+the explosion and which transforms the power obtained by the combustion
+of gas to mechanical motion by means of the connecting rod to which it
+is attached. The piston is one of the simplest elements of the motor,
+and it is one component which does not vary much in form in different
+types of motors. The piston is a cylindrical member provided with a
+series of grooves in which packing rings are placed on the outside and
+two bosses which serve to hold the wrist pin in its interior. It is
+usually made of cast iron or aluminum, though in some motors where
+extreme lightness is desired, such as those used for aëronautic work, it
+may be made of steel. The use of the more resisting material enables the
+engineer to use lighter sections where it is important that the weight
+of this member be kept as low as possible consistent with strength.
+
+[Illustration: Fig. 116.--Forms of Pistons Commonly Employed in Gasoline
+Engines. A--Dome Head Piston and Three Packing Rings. B--Flat Top Form
+Almost Universally Used. C--Concave Piston Utilized in Knight Motors and
+Some Having Overhead Valves. D--Two-Cycle Engine Member with Deflector
+Plate Cast Integrally. E--Differential of Two-Diameter Piston Used in
+Some Engines Operating on Two-Cycle Principle.]
+
+A number of piston types are shown at Fig. 116. That at A has a round
+top and is provided with four split packing rings and two oil grooves. A
+piston of this type is generally employed in motors where the combustion
+chamber is large and where it is desired to obtain a higher degree of
+compression than would be possible with a flat top piston. This
+construction is also stronger because of the arched piston top. The most
+common form of piston is that shown at B, and it differs from that
+previously described only in that it has a flat top. The piston outlined
+in section at C is a type used on some of the sleeve-valve motors of the
+Knight pattern, and has a concave head instead of the convex form shown
+at A. The design shown at D in side and plan views is the conventional
+form employed in two-cycle engines. The deflector plate on the top of
+the cylinder is cast integral and is utilized to prevent the incoming
+fresh gases from flowing directly over the piston top and out of the
+exhaust port, which is usually opposite the inlet opening. On these
+types of two-cycle engines where a two-diameter cylinder is employed,
+the piston shown at E is used. This is known as a "differential
+piston," and has an enlarged portion at its lower end which fits the
+pumping cylinder. The usual form of deflector plate is provided at the
+top of the piston and one may consider it as two pistons in one.
+
+[Illustration: Fig. 117.--Typical Methods of Piston Pin Retention
+Generally Used in Engines of American Design. A--Single Set Screw and
+Lock Nut. B--Set Screw and Check Nut Fitting Groove in Wrist Pin. C,
+D--Two Locking Screws Passing Into Interior of Hollow Wrist Pin.
+E--Split Ring Holds Pin in Place. F--Use of Taper Expanding Plugs
+Outlined. G--Spring Pressed Plunger Type. H--Piston Pin Pinned to
+Connecting Rod. I--Wrist Pin Clamped in Connecting Rod Small End by
+Bolt.]
+
+[Illustration: Fig. 118.--Typical Piston and Connecting Rod Assembly.]
+
+[Illustration: Fig. 119.--Parts of Sturtevant Aviation Engine.
+A--Cylinder Head Showing Valves. B--Connecting Rod. C--Piston and
+Rings.]
+
+One of the important conditions in piston design is the method of
+securing the wrist pin which is used to connect the piston to the upper
+end of the connecting rod. Various methods have been devised to keep the
+pin in place, the most common of these being shown at Fig. 117. The
+wrist pin should be retained by some positive means which is not liable
+to become loose under the vibratory stresses which obtain at this point.
+If the wrist pin was free to move it would work out of the bosses
+enough so that the end would bear against the cylinder wall. As it is
+usually made of steel, which is a harder material than cast iron used in
+cylinder construction, the rubbing action would tend to cut a groove in
+the cylinder wall which would make for loss of power because it would
+permit escape of gas. The wrist pin member is a simple cylindrical
+element that fits the bosses closely, and it may be either hollow or
+solid stock. A typical piston and connecting rod assembly which shows a
+piston in section also is given at Fig. 118. The piston of the
+Sturtevant aëronautical motor is shown at Fig. 119, the aluminum piston
+of the Thomas airplane motor with piston rings in place is shown at Fig.
+120. A good view of the wrist pin and connecting rod are also given. The
+iron piston of the Gnome "Monosoupape" airplane engine and the
+unconventional connecting rod assembly are clearly depicted at Fig 121.
+
+[Illustration: Fig. 120.--Aluminum Piston and Light But Strong Steel
+Connecting Rod and Wrist Pin of Thomas Aviation Engine.]
+
+The method of retention shown at A is the simplest and consists of a set
+screw having a projecting portion passing into the wrist pin and
+holding it in place. The screw is kept from turning or loosening by
+means of a check nut. The method outlined at B is similar to that shown
+at A, except that the wrist pin is solid and the point of the set screw
+engages an annular groove turned in the pin for its reception. A very
+positive method is shown at C. Here the retention screws pass into the
+wrist pin and are then locked by a piece of steel wire which passes
+through suitable holes in the ends. The method outlined at D is
+sometimes employed, and it varies from that shown at C only in that the
+locking wire, which is made of spring steel, is passed through the heads
+of the locking screws. Some designers machine a large groove around the
+piston at such a point that when the wrist pin is put in place a large
+packing ring may be sprung in the groove and utilized to hold the wrist
+pin in place.
+
+[Illustration: Fig. 121.--Cast Iron Piston of "Monosoupape" Gnome Engine
+Installed On One of the Short Connecting Rods.]
+
+The system shown at F is not so widely used as the simpler methods,
+because it is more costly and does not offer any greater security when
+the parts are new than the simple lock shown at A. In this a hollow
+wrist pin is used, having a tapered thread cut at each end. The wrist
+pin is slotted at three or four points, for a distance equal to the
+length of the boss, and when taper expansion plugs are screwed in place
+the ends of the wrist pin are expanded against the bosses. This method
+has the advantage of providing a certain degree of adjustment if the
+wrist pin should loosen up after it has been in use for some time. The
+taper plugs would be screwed in deeper and the ends of the wrist pin
+expanded proportionately to take up the loss motion. The method shown at
+G is an ingenious one. One of the piston bosses is provided with a
+projection which is drilled out to receive a plunger. The wrist pin is
+provided with a hole of sufficient size to receive the plunger, which is
+kept in place by means of a spring in back of it. This makes a very
+positive lock and one that can be easily loosened when it is desired to
+remove the wrist pin. To unlock, a piece of fine rod is thrust into the
+hole at the bottom of the boss which pushes the plunger back against the
+spring until the wrist pin can be pushed out of the piston.
+
+Some engineers think it advisable to oscillate the wrist pin in the
+piston bosses, instead of in the connecting rod small end. It is argued
+that this construction gives more bearing surface at the wrist pin and
+also provides for more strength because of the longer bosses that can be
+used. When this system is followed the piston pin is held in place by
+locking it to the connecting rod by some means. At H the simplest method
+is outlined. This consisted of driving a taper pin through both rod and
+wrist pin and then preventing it from backing out by putting a split
+cotter through the small end of the tapered locking pin. Another method,
+which is depicted at I, consists of clamping the wrist pin by means of a
+suitable bolt which brings the slit connecting rod end together as
+shown.
+
+
+ALUMINUM FOR CYLINDERS AND PISTONS
+
+Aluminum pistons outlined at Fig. 122, have replaced cast iron members
+in many airplane engines, as these weigh about one-third as much as the
+cast iron forms of the same size, while the reduction in the inertia
+forces has made it possible to increase the engine speed without
+correspondingly stressing the connecting rods, crank-shaft and engine
+bearings.
+
+[Illustration: Fig. 122.--Types of Aluminum Pistons Used In Aviation
+Engines.]
+
+Aluminum has not only been used for pistons, but a number of motors will
+be built for the coming season that will use aluminum cylinder block
+castings as well. Of course, the aluminum alloy is too soft to be used
+as a bearing for the piston, and it will not withstand the hammering
+action of the valve. This makes the use of cast iron or steel imperative
+in all motors. When used in connection with an aluminum cylinder block
+the cast iron pieces are placed in the mould so that they act as
+cylinder liners and valve seats, and the molten metal is poured around
+them when the cylinder is cast. It is said that this construction
+results in an intimate bond between the cast iron and the surrounding
+aluminum metal. Steel liners may also be pressed into the aluminum
+cylinders after these are bored out to receive them. Aluminum has for a
+number of years been used in many motor car parts. Alloys have been
+developed that have greater strength than cast iron and that are not so
+brittle. Its use for manifolds and engine crank and gear cases has been
+general for a number of years.
+
+At first thought it would seem as though aluminum would be entirely
+unsuited for use in those portions of internal combustion engines
+exposed to the heat of the explosion, on account of the low melting
+point of that metal and its disadvantageous quality of suddenly
+"wilting" when a critical point in the temperature is reached. Those who
+hesitated to use aluminum on account of this defect lost sight of the
+great heat conductivity of that metal, which is considerably more than
+that of cast iron. It was found in early experiments with aluminum
+pistons that this quality of quick radiation meant that aluminum pistons
+remained considerably cooler than cast iron ones in service, which was
+attested to by the reduced formation of carbon deposit thereon. The use
+of aluminum makes possible a marked reduction in power plant weight. A
+small four-cylinder engine which was not particularly heavy even with
+cast iron cylinders was found to weigh 100 pounds less when the cylinder
+block, pistons, and upper half of the crank-case had been made of
+aluminum instead of cast iron. Aluminum motors are no longer an
+experiment, as a considerable number of these have been in use on cars
+during the past year without the owners of the cars being apprised of
+the fact. Absolutely no complaint was made in any case of the aluminum
+motor and it was demonstrated, in addition to the saving in weight, that
+the motors cost no more to assemble and cooled much more efficiently
+than the cast iron form. One of the drawbacks to the use of aluminum is
+its growing scarcity, which results in making it a "near precious"
+metal.
+
+
+PISTON RING CONSTRUCTION
+
+As all pistons must be free to move up and down in the cylinder with
+minimum friction, they must be less in diameter than the bore of the
+cylinder. The amount of freedom or clearance provided varies with the
+construction of the engine and the material the piston is made of, as
+well as its size, but it is usual to provide from .005 to .010 of an
+inch to compensate for the expansion of the piston due to heat and also
+to leave sufficient clearance for the introduction of lubricant between
+the working surfaces. Obviously, if the piston were not provided with
+packing rings, this amount of clearance would enable a portion of the
+gases evolved when the charge is exploded to escape by it into the
+engine crank-case. The packing members or piston rings, as they are
+called, are split rings of cast iron, which are sprung into suitable
+grooves machined on the exterior of the piston, three or four of these
+being the usual number supplied. These have sufficient elasticity so
+that they bear tightly against the cylinder wall and thus make a
+gas-tight joint. Owing to the limited amount of surface in contact with
+the cylinder wall and the elasticity of the split rings the amount of
+friction resulting from the contact of properly fitted rings and the
+cylinder is not of enough moment to cause any damage and the piston is
+free to slide up and down in the cylinder bore.
+
+[Illustration: Fig. 123.--Types of Piston Rings and Ring Joints.
+A--Concentric Ring. B--Eccentrically Machined Form. C--Lap Joint Ring.
+D--Butt Joint, Seldom Used. E--Diagonal Cut Member, a Popular Form.]
+
+These rings are made in two forms, as outlined at Fig. 123. The design
+shown at A is termed a "concentric ring," because the inner circle is
+concentric with the outer one and the ring is of uniform thickness at
+all points. The ring shown at B is called an "eccentric ring," and it is
+thicker at one part than at others. It has theoretical advantages in
+that it will make a tighter joint than the other form, as it is claimed
+its expansion due to heat is more uniform. The piston rings must be
+split in order that they may be sprung in place in the grooves, and also
+to insure that they will have sufficient elasticity to take the form of
+the cylinder at the different points in their travel. If the cylinder
+bore varies by small amounts the rings will spring out at the points
+where the bore is larger than standard, and spring in at those portions
+where it is smaller than standard.
+
+It is important that the joint should be as nearly gas-tight as
+possible, because if it were not a portion of the gases would escape
+through the slots in the piston rings. The joint shown at C is termed a
+"lap joint," because the ends of the ring are cut in such a manner that
+they overlap. This is the approved joint. The butt joint shown at D is
+seldom used and is a very poor form, the only advantage being its
+cheapness. The diagonal cut shown at E is a compromise between the very
+good form shown at C and the poor joint depicted at D. It is also widely
+used, though most constructors prefer the lap joint, because it does not
+permit the leakage of gas as much as the other two types.
+
+There seems to be some difference of opinion relative to the best piston
+ring type--some favoring the eccentric pattern, others the concentric
+form. The concentric ring has advantages from the lubricating engineer's
+point of view; as stated by the Platt & Washburn Company in their
+text-book on engine lubrication, the smaller clearance behind the ring
+possible with the ring of uniform section is advantageous.
+
+Fig. 124, A, shows a concentric piston ring in its groove. Since the
+ring itself is concentric with the groove, very small clearance between
+the back of the ring and the bottom of its groove may be allowed. Small
+clearance leaves less space for the accumulation of oil and carbon
+deposits. The gasket effect of this ring is uniform throughout the
+entire length of its edges, which is its marked advantage over the
+eccentric ring. This type of piston ring rarely burns fast in its
+groove. There are a large number of different concentric rings
+manufactured of different designs and of different efficiency.
+
+[Illustration: Fig. 124.--Diagrams Showing Advantages of Concentric
+Piston Rings.]
+
+Figs. 124, B and 124, C show eccentric rings assembled in the ring
+groove. It will be noted that there is a large space between the thin
+ends of this ring and the bottom of the groove. This empty space fills
+up with oil which in the case of the upper ring frequently is
+carbonized, restricting the action of the ring and nullifying its
+usefulness. The edges of the thin ends are not sufficiently wide to
+prevent rapid escape of gases past them. In a practical way this leakage
+means loss of compression and noticeable drop in power. When new and
+properly fitted, very little difference can be noted between the
+tightness of eccentric and concentric rings. Nevertheless, after several
+months' use, a more rapid leakage will always occur past the eccentric
+than past the concentric. If continuous trouble with the carbonization
+of cylinders, smoking and sooting of spark-plugs is experienced, it is
+a sure indication that mechanical defects exist in the engine, assuming
+of course, that a suitable oil has been used. Such trouble can be
+greatly lessened, if not entirely eliminated, by the application of
+concentric rings (lap joint), of any good make, properly fitted into the
+grooves of the piston. Too much emphasis cannot be put upon this point.
+If the oil used in the engine is of the correct viscosity, and serious
+carbon deposit, smoking, etc., still result, the only certain remedy
+then is to have the cylinders rebored and fitted with properly designed,
+oversized pistons and piston rings.
+
+
+LEAK-PROOF PISTON RINGS
+
+In order to reduce the compression loss and leakage of gas by the
+ordinary simple form of diagonal or lap joint one-piece piston ring a
+number of compound rings have been devised and are offered by their
+makers to use in making replacements. The leading forms are shown at
+Fig. 125. That shown at A is known as the "Statite" and consists of
+three rings, one carried inside while the other two are carried on the
+outside. The ring shown at B is a double ring and is known as the
+McCadden. This is composed of two thin concentric lap joint rings so
+disposed relative to each other that the opening in the inner ring comes
+opposite to the opening in the outer ring.
+
+The form shown at C is known as the "Leektite," and is a single ring
+provided with a peculiar form of lap and dove tail joint. The ring shown
+at D is known as the "Dunham" and is of the double concentric type being
+composed of two rings with lap joints which are welded together at a
+point opposite the joint so that there is no passage by which the gas
+can escape. The Burd high compression ring is shown at E. The joints of
+these rings are sealed by means of an H-shaped coupler of bronze which
+closes the opening. The ring ends are made with tongues which interlock
+with the coupling. The ring shown at F is called the "Evertite" and is
+a three-piece ring composed of three members as shown in the sectional
+view below the ring. The main part or inner ring has a circumferential
+channel in which the two outer rings lock, the resulting cross-section
+being rectangular just the same as that of a regular pattern ring. All
+three rings are diagonally split and the joints are spaced equally and
+the distances maintained by small pins. This results in each joint being
+sealed by the solid portion of the other rings.
+
+[Illustration: Fig. 125.--Leak-Proof and Other Compound Piston Rings.]
+
+The use of a number of light steel rings instead of one wide ring in the
+groove is found on a number of automobile power plants, but as far as
+known, this construction is not used in airplane power plants. It is
+contended that where a number of light rings is employed a more flexible
+packing means is obtained and the possibility of leakage is reduced.
+Rings of this design are made of square section steel wire and are given
+a spring temper. Owing to the limited width the diagonal cut joint is
+generally employed instead of the lap joint which is so popular on wider
+rings.
+
+
+KEEPING OIL OUT OF COMBUSTION CHAMBERS
+
+An examination of the engine design that is economical in oil
+consumption discloses the use of tight piston rings, large centrifugal
+rings on the crank-shaft where it passes through the case, ample cooling
+fins in the pistons, vents between the crank-case chamber and the valve
+enclosures, etc. Briefly put, cooling of the oil in this engine has been
+properly cared for and leakage reduced to a minimum. To be specific
+regarding details of design: Oil surplus can be kept out of the
+explosion chambers by leaving the lower edge of the piston skirt sharp
+and by the use of a shallow groove (C), Fig. 126, just below the lower
+piston ring. Small holes are bored through the piston walls at the base
+of this groove and communicate with the crank-case. The similarity of
+the sharp edges of piston skirt (D) and piston ring to a carpenter's
+plane bit, makes their operation plain.
+
+[Illustration: Fig. 126.--Sectional View of Engine Showing Means of
+Preventing Oil Leakage By Piston Rings.]
+
+The cooling of oil in the sump (A) can be accomplished most effectively
+by radiating fins on its outer surface. The lower crank-case should be
+fully exposed to the outer air. A settling basin for sediment (B) should
+be provided having a cubic content not less than one-tenth of the total
+oil capacity as outlined at Fig. 126. The depth of this basin should be
+at least 2-1/2 inches, and its walls vertical, as shown, to reduce the
+mixing of sediment with the oil in circulation. The inlet opening to the
+oil pump should be near the top of the sediment basin in order to
+prevent the entrance into the pump with the oil of any solid matter or
+water condensed from the products of combustion. This sediment basin
+should be drained after every five to seven hours air service of an
+airplane engine. Concerning filtering screens there is little to be
+said, save that their areas should be ample and the mesh coarse enough
+(one-sixteenth of an inch) to offer no serious resistance to the free
+flow of cold or heavy oil through them; otherwise the oil in the
+crank-case may build up above them to an undesirable level. The
+necessary frequency of draining and flushing out the oil sump differs
+greatly with the age (condition) of the engine and the suitability of
+the oil used. In broad terms, the oil sump of a new engine should be
+thoroughly drained and flushed with kerosene at the end of the first
+200 miles, next at the end of 500 miles and thereafter every 1,000
+miles. While these instructions apply specifically to automobile motors,
+it is very good practice to change the oil in airplane engines
+frequently. In many cases, the best results have been secured when the
+oil supply is completely replenished every five hours that the engine is
+in operation.
+
+
+CONNECTING ROD FORMS
+
+The connecting rod is the simple member that joins the piston to the
+crank-shaft and which transmits the power imparted to the piston by the
+explosion so that it may be usefully applied. It transforms the
+reciprocating movement of the piston to a rotary motion at the
+crank-shaft. A typical connecting rod and its wrist pin are shown at
+Fig. 120. It will be seen that it has two bearings, one at either end.
+The small end is bored out to receive the wrist pin which joins it to
+the piston, while the large end has a hole of sufficient size to go on
+the crank-pin. The airplane and automobile engine connecting rod is
+invariably a steel forging, though in marine engines it is sometimes
+made a steel or high tensile strength bronze casting. In all cases it is
+desirable to have softer metals than the crank-shaft and wrist pin at
+the bearing point, and for this reason the connecting rod is usually
+provided with bushings of anti-friction or white metal at the lower end,
+and bronze at the upper. The upper end of the connecting rod may be one
+piece, because the wrist pin can be introduced after it is in place
+between the bosses of the piston. The lower bearing must be made in two
+parts in most cases, because the crank-shaft cannot be passed through
+the bearing owing to its irregular form. The rods of the Gnome engine
+are all one piece types, as shown at Fig. 127, owing to the construction
+of the "mother" rod which receives the crank-pins. The complete
+connecting rod assembly is shown in Fig. 121, also at A, Fig. 127. The
+"mother" rod, with one of the other rods in place and one about to be
+inserted, is shown at Fig. 127, B. The built-up crank-shaft which makes
+this construction feasible is shown at Fig. 127, C.
+
+[Illustration: Fig. 127.--Connecting Rod and Crank-Shaft Construction of
+Gnome "Monosoupape" Engine.]
+
+Some of the various designs of connecting rods that have been used are
+shown at Fig. 128. That at A is a simple form often employed in
+single-cylinder motors, having built-up crank-shafts. Both ends of the
+connecting rod are bushed with a one-piece bearing, as it can be
+assembled in place before the crank-shaft assembly is built up. A
+built-up crank-shaft such as this type of connecting rod would be used
+with is shown at Fig. 106. The pattern shown at B is one that has been
+used to some extent on heavy work, and is known as the "marine type." It
+is made in three pieces, the main portion being a steel forging having a
+flanged lower end to which the bronze boxes are secured by bolts. The
+modified marine type depicted at C is the form that has received the
+widest application in automobile and aviation engine construction. It
+consists of two pieces, the main member being a steel drop forging
+having the wrist-pin bearing and the upper crank-pin bearing formed
+integral, while the lower crank-pin bearing member is a separate forging
+secured to the connecting rod by bolts. In this construction bushings of
+anti-friction metal are used at the lower end, and a bronze bushing is
+forced into the upper- or wrist-pin end. The rod shown at D has also
+been widely used. It is similar in construction to the form shown at C,
+except that the upper end is split in order to permit of a degree of
+adjustment of the wrist-pin bushing, and the lower bearing cap is a
+hinged member which is retained by one bolt instead of two. When it is
+desired to assemble it on the crank-shaft the lower cap is swung to one
+side and brought back into place when the connecting rod has been
+properly located. Sometimes the lower bearing member is split diagonally
+instead of horizontally, such a construction being outlined at E.
+
+[Illustration: Fig. 128.--Connecting Rod Types Summarized.
+A--Single Connecting Rod Made in One Piece, Usually Fitted in Small
+Single-Cylinder Engines Having Built-Up Crank-Shafts. B--Marine Type, a
+Popular Form on Heavy Engines. C--Conventional Automobile Type, a
+Modified Marine Form. D--Type Having Hinged Lower Cap and Split Wrist
+Pin Bushing. E--Connecting Rod Having Diagonally Divided Big End.
+F--Ball-Bearing Rod. G--Sections Showing Structural Shapes Commonly
+Employed in Connecting Rod Construction.]
+
+In a number of instances, instead of plain bushed bearings anti-friction
+forms using ball or rollers have been used at the lower end. A
+ball-bearing connecting rod is shown at F. The big end may be made in
+one piece, because if it is possible to get the ball bearing on the
+crank-pins it will be easy to put the connecting rod in place. Ball
+bearings are not used very often on connecting rod big ends because of
+difficulty of installation, though when applied properly they give
+satisfactory service and reduce friction to a minimum. One of the
+advantages of the ball bearing is that it requires no adjustment,
+whereas the plain bushings depicted in the other connecting rods must be
+taken up from time to time to compensate for wear.
+
+This can be done in forms shown at B, C, D, and E by bringing the lower
+bearing caps closer to the upper one and scraping out the brasses to fit
+the shaft. A number of liners or shims of thin brass or copper stock,
+varying from .002 inch to .005 inch, are sometimes interposed between
+the halves of the bearings when it is first fitted to the crank-pin. As
+the brasses wear the shims may be removed and the portions of the
+bearings brought close enough together to take up any lost motion that
+may exist, though in some motors no shims are provided and depreciation
+can be remedied only by installing new brasses and scraping to fit.
+
+[Illustration: Fig. 129.--Double Connecting Rod Assembly For Use On
+Single Crank-Pin of Vee Engine.]
+
+The various structural shapes in which connecting rods are formed are
+shown in section at G. Of these the I section is most widely used in
+airplane engines, because it is strong and a very easy shape to form by
+the drop-forging process or to machine out of the solid bar when extra
+good steel is used. Where extreme lightness is desired, as in small
+high-speed motors used for cycle propulsion, the section shown at the
+extreme left is often used. If the rod is a cast member as in some
+marine engines, the cross, hollow cylinder, or U sections are sometimes
+used. If the sections shown at the right are employed, advantage is
+often taken of the opportunity for passing lubricant through the center
+of the hollow round section on vertical motors or at the bottom of the U
+section, which would be used on a horizontal cylinder power plant.
+
+[Illustration: Fig. 130.--Another Type of Double Connecting Rod for Vee
+Engines.]
+
+Connecting rods of Vee engines are made in two distinct styles. The
+forked or "scissors" joint rod assembly is employed when the cylinders
+are placed directly opposite each other. The "blade" rod, as shown at
+Fig. 129, fits between the lower ends of the forked rod, which oscillate
+on the bearing which encircles the crank-pin. The lower end of the
+"blade" rod is usually attached to the bearing brasses, the ends of the
+"forked" rod move on the outer surfaces of the brasses. Another form of
+rod devised for use under these conditions is shown at Fig. 130 and
+installed in an aviation engine at Fig. 132. In this construction the
+shorter rod is attached to a boss on the master rod by a short pin to
+form a hinge and to permit the short rod to oscillate as the conditions
+dictate. This form of rod can be easily adjusted when the bearing
+depreciates, a procedure that is difficult with the forked type rod. The
+best practice, in the writer's opinion, is to stagger the cylinders and
+use side-by-side rods as is done in the Curtiss engine. Each rod may be
+fitted independently of the other and perfect compensation for wear of
+the big ends is possible.
+
+[Illustration: Fig. 131.--Part Sectional View of Wisconsin Aviation
+Engine, Showing Four-Bearing Crank-Shaft, Overhead Cam-Shaft, and Method
+of Combining Cylinders in Pairs.]
+
+[Illustration: Fig. 132.--Part Sectional View of Renault Twelve-Cylinder
+Water-Cooled Engine, Showing Connecting Rod Construction and Other
+Important Internal Parts.]
+
+
+CAM-SHAFT AND CRANK-SHAFT DESIGN
+
+Before going extensively into the subject of crank-shaft construction it
+will be well to consider cam-shaft design, which is properly a part of
+the valve system and which has been considered in connection with the
+other elements which have to do directly with cylinder construction to
+some extent. Cam-shafts are usually simple members carried at the base
+of the cylinder in the engine case of Vee type motors by suitable
+bearings and having the cams employed to lift the valves attached at
+intervals. A typical cam-shaft design is shown at Fig. 133. Two main
+methods of cam-shaft construction are followed--that in which the cams
+are separate members, keyed and pinned to the shaft, and the other where
+the cams are formed integral, the latter being the most suitable for
+airplane engine requirements.
+
+[Illustration: Fig. 133.--Typical Cam-Shaft, with Valve Lifting Cams and
+Gears to Operate Auxiliary Devices Forged Integrally.]
+
+The cam-shafts shown at Figs. 133 and 134, B, are of the latter type, as
+the cams are machined integrally. In this case not only the cams but
+also the gears used in driving the auxiliary shafts are forged integral.
+This is a more expensive construction, because of the high initial cost
+of forging dies as well as the greater expense of machining. It has the
+advantage over the other form in which the cams are keyed in place in
+that it is stronger, and as the cams are a part of the shaft they can
+never become loose, as might be possible where they are separately
+formed and assembled on a simple shaft.
+
+[Illustration: Fig. 134.--Important Parts of Duesenberg Aviation Engine.
+A--Three Main Bearing Crank-Shaft. B--Cam-Shaft with Integral Cams.
+C--Piston and Connecting Rod Assembly. D--Valve Rocker Group. E--Piston.
+F--Main Bearing Brasses.]
+
+The importance of the crank-shaft has been previously considered, and
+some of its forms have been shown in views of the motors presented in
+earlier portions of this work. The crank-shaft is one of the parts
+subjected to the greatest strain and extreme care is needed in its
+construction and design, because practically the entire duty of
+transmitting the power generated by the motor to the gearset devolves
+upon it. Crank-shafts are usually made of high tensile strength steel of
+special composition. They may be made in four ways, the most common
+being from a drop or machine forging which is formed approximately to
+the shape of the finished shaft and in rare instances (experimental
+motors only) they may be steel castings. Sometimes they are made from
+machine forgings, where considerably more machine work is necessary than
+would be the case where the shaft is formed between dies. Some engineers
+favor blocking the shaft out of a solid slab of metal and then machining
+this rough blank to form. In some radial-cylinder motors of the Gnome
+and Le Rhone type the crank-shafts are built up of two pieces, held
+together by taper fastenings or bolts.
+
+[Illustration: Fig. 135.--Showing Method of Making Crank-Shaft. A--The
+Rough Steel Forging Before Machining. B--The Finished Six-Throw,
+Seven-Bearing Crank-Shaft.]
+
+The form of the shaft depends on the number of cylinders and the form
+has material influence on the method of construction. For instance, a
+four-cylinder crank-shaft could be made by either of the methods
+outlined. On the other hand, a three- or six-cylinder shaft is best made
+by the machine forging process, because if drop forged or cut from the
+blank it will have to be heated and the crank throws bent around so that
+the pins will lie in three planes one hundred and twenty degrees apart,
+while the other types described need no further attention, as the
+crank-pins lie in planes one hundred and eighty degrees apart. This can
+be better understood by referring to Fig. 135, which shows a
+six-cylinder shaft in the rough and finished stages. At A the
+appearance of the machine forging before any of the material is removed
+is shown, while at B the appearance of the finished crank-shaft is
+clearly depicted. The built-up crank-shaft is seldom used on
+multiple-cylinder motors, except in some cases where the crank-shafts
+revolve on ball bearings as in some automobile racing engines.
+
+[Illustration: Fig. 136.--Showing Form of Crank-Shaft for Twin-Cylinder
+Opposed Power Plant.]
+
+[Illustration: Fig. 137.--Crank-Shaft of Thomas-Morse Eight-Cylinder Vee
+Engine.]
+
+Crank-shaft form will vary with a number of cylinders and it is possible
+to use a number of different arrangements of crank-pins and bearings for
+the same number of cylinders. The simplest form of crank-shaft is that
+used on simple radial cylinder motors as it would consist of but one
+crank-pin, two webs, and the crank-shaft. As the number of cylinders
+increase in Vee motors as a general rule more crank-pins are used. The
+crank-shaft that would be used on a two-cylinder opposed motor is shown
+at Fig. 136. This has two throws and the crank-pins are spaced 180
+degrees apart. The bearings are exceptionally long. Four-cylinder
+crank-shafts may have two, three or five main bearings and three or four
+crank-pins. In some forms of two-bearing crank-shafts, such as used when
+four-cylinders are cast in a block, or unit casting, two of the pistons
+are attached to one common crank-pin, so that in reality the crank-shaft
+has but three crank-pins. A typical three bearing, four-cylinder
+crank-shaft is shown at Fig. 134, A. The same type can be used for an
+eight-cylinder Vee engine, except for the greater length of crank-pins
+to permit of side by side rods as shown at Fig. 137. Six cylinder
+vertical tandem and twelve-cylinder Vee engine crank-shafts usually have
+four or seven main bearings depending upon the disposition of the
+crank-pins and arrangement of cylinders. At Fig. 138, A, the bottom
+view of a twelve-cylinder engine with bottom half of crank case removed
+is given. This illustrates clearly the arrangement of main bearings when
+the crank-shaft is supported on four journals. The crank-shaft shown at
+Fig. 138, B, is a twelve-cylinder seven-bearing type.
+
+[Illustration: Fig. 138.--Crank-Case and Crank-Shaft Construction for
+Twelve-Cylinder Motors. A--Duesenberg. B--Curtiss.]
+
+[Illustration: Fig. 139.--Counterbalanced Crank-Shafts Reduce Engine
+Vibration and Permit of Higher Rotative Speeds.]
+
+In some automobile engines, extremely good results have been secured in
+obtaining steady running with minimum vibration by counterbalancing the
+crank-shafts as outlined at Fig. 139. The shaft at A is a type suitable
+for a high speed four-cylinder vertical or an eight-cylinder Vee type.
+That at B is for a six-cylinder vertical or a twelve-cylinder V with
+scissors joint rods. If counterbalancing crank-shafts helps in an
+automobile engine, it should have advantages of some moment in airplane
+engines, even though the crank-shaft weight is greater.
+
+
+BALL-BEARING CRANK-SHAFTS
+
+While crank-shafts are usually supported in plain journals there seems
+to be a growing tendency of late to use anti-friction bearings of the
+ball type for their support. This is especially noticeable on block
+motors where but two main bearings are utilized. When ball bearings are
+selected with proper relation to the load which obtains they will give
+very satisfactory service. They permit the crank-shaft to turn with
+minimum friction, and if properly selected will never need adjustment.
+The front end is supported by a bearing which is clamped in such a
+manner that it will take a certain amount of load in a direction
+parallel to the axis of the shaft, while the rear end is so supported
+that the outer race of the bearing has a certain amount of axial freedom
+or "float." The inner race or cone of each bearing is firmly clamped
+against shoulders on the crank-shaft. At the front end of the
+crank-shaft timing gear and a suitable check nut are used, while at the
+back end the bearing is clamped by a threaded retention member between
+the fly-wheel and a shoulder on the crank-shaft. The fly-wheel is held
+in place by a taper and key retention. The ball bearings are carried in
+a light housing of bronze or malleable iron, which in turn are held in
+the crank-case by bolts. The Renault engine uses ball bearings at front
+and rear ends of the crank-shaft, but has plain bearings around
+intermediate crank-shaft journals. The rotary engines of the Gnome, Le
+Rhone and Clerget forms would not be practical if ball bearings were not
+used as the bearing friction and consequent depreciation would be very
+high.
+
+
+ENGINE-BASE CONSTRUCTION
+
+One of the important parts of the power plant is the substantial casing
+or bed member, which is employed to support the cylinders and
+crank-shaft and which is attached directly to the fuselage engine
+supporting members. This will vary widely in form, but as a general
+thing it is an approximately cylindrical member which may be divided
+either vertically or horizontally in two or more parts. Airplane engine
+crank-cases are usually made of aluminum, a material which has about the
+same strength as cast iron, but which only weighs a third as much. In
+rare cases cast iron is employed, but is not favored by most engineers
+because of its brittle nature, great weight and low resistance to
+tensile stresses. Where exceptional strength is needed alloys of bronze
+may be used, and in some cases where engines are produced in large
+quantities a portion of the crank-case may be a sheet steel or aluminum
+stamping.
+
+[Illustration: Fig. 140.--View of Thomas 135 Horse-Power Aeromotor,
+Model 8, Showing Conventional Method of Crank-Case Construction.]
+
+[Illustration: Fig. 141.--Views of Upper Half of Thomas Aeromotor
+Crank-Case.]
+
+Crank-cases are always large enough to permit the crank-shaft and parts
+attached to it to turn inside and obviously its length is determined by
+the number of cylinders and their disposition. The crank-case of the
+radial cylinder or double-opposed cylinder engine would be substantially
+the same in length. That of a four-cylinder will vary in length with
+the method of casting the cylinder. When the four-cylinders are cast in
+one unit and a two-bearing crank-shaft is used, the crank-case is a very
+compact and short member. When a three-bearing crank-shaft is utilized
+and the cylinders are cast in pairs, the engine base is longer than it
+would be to support a block casting, but is shorter than one designed to
+sustain individual cylinder castings and a five-bearing crank-shaft. It
+is now common construction to cast an oil container integral with the
+bottom of the engine base and to draw the lubricating oil from it by
+means of a pump, as shown at Fig. 140. The arms by which the motor is
+supported in the fuselage are substantial-ribbed members cast
+integrally with the upper half.
+
+[Illustration: Fig. 142.--Method of Constructing Eight-Cylinder Vee
+Engine, Possible if Aluminum Cylinder and Crank-Case Castings are Used.]
+
+[Illustration: Fig. 143.--Simple and Compact Crank-Case, Possible When
+Radial Cylinder Engine Design is Followed.]
+
+The approved method of crank-case construction favored by the majority
+of engineers is shown at the top of Fig. 141, bottom side up. The upper
+half not only forms a bed for the cylinder but is used to hold the
+crank-shaft as well. In the illustration, the three-bearing boxes form
+part of the case, while the lower brasses are in the form of separately
+cast caps retained by suitable bolts. In the construction outlined the
+bottom part of the case serves merely as an oil container and a
+protection for the interior mechanism of the motor. The cylinders are
+held down by means of studs screwed into the crank-case top, as shown at
+Fig. 141, lower view. If the aluminum cylinder motor has any future, the
+method of construction outlined at Fig. 142, which has been used in cast
+iron for an automobile motor, might be used for an eight-cylinder Vee
+engine for airplane use. The simplicity of the crank-case needed for a
+revolving cylinder motor and its small weight can be well understood by
+examination of the illustration at Fig. 143, which shows the engine
+crank-case for the nine-cylinder "Monosoupape" Gnome engine. This
+consists of two accurately machined forgings held together by bolts as
+clearly indicated.
+
+
+
+
+CHAPTER X
+
+    Power Plant Installation--Curtiss OX-2 Engine Mounting and
+    Operating Rules--Standard S. A. E. Engine Bed Dimensions--
+    Hall-Scott Engine Installation and Operation--Fuel System Rules
+    --Ignition System--Water System--Preparations to Start Engine--
+    Mounting Radial and Rotary Engines--Practical Hints to Locate
+    Engine Troubles--All Engine Troubles Summarized--Location of
+    Engine Troubles Made Easy.
+
+
+The proper installation of the airplane power plant is more important
+than is generally supposed, as while these engines are usually well
+balanced and run with little vibration, it is necessary that they be
+securely anchored and that various connections to the auxiliary parts be
+carefully made in order to prevent breakage from vibration and that
+attendant risk of motor stoppage while in the air. The type of motor to
+be installed determines the method of installation to be followed. As a
+general rule six-cylinder vertical engine and eight-cylinder Vee type
+are mounted in substantially the same way. The radial, fixed cylinder
+forms and the radial, rotary cylinder Gnome and Le Rhone rotary types
+require an entirely different method of mounting. Some unconventional
+mountings have been devised, notably that shown at Fig. 144, which is a
+six-cylinder German engine that is installed in just the opposite way to
+that commonly followed. The inverted cylinder construction is not
+generally followed because even with pressure feed, dry crank-case type
+lubricating system there is considerable danger of over-lubrication and
+of oil collecting and carbonizing in the combustion chamber and gumming
+up the valve action much quicker than would be the case if the engine
+was operated in the conventional upright position. The reason for
+mounting an engine in this way is to obtain a lower center of gravity
+and also to make for more perfect streamlining of the front end of the
+fuselage in some cases. It is rather doubtful if this slight advantage
+will compensate for the disadvantages introduced by this unusual
+construction. It is not used to any extent now but is presented merely
+to show one of the possible systems of installing an airplane engine.
+
+[Illustration: Fig. 144.--Unconventional Mounting of German Inverted
+Cylinder Motor.]
+
+[Illustration: Fig. 145.--How Curtiss Model OX-2 Motor is Installed in
+Fuselage of Curtiss Tractor Biplane. Note Similarity of Mounting to
+Automobile Power Plant.]
+
+In a number of airplanes of the tractor-biplane type the power plant
+installation is not very much different than that which is found in
+automobile practice. The illustration at Fig. 145 is a very clear
+representation of the method of mounting the Curtiss eight-cylinder 90
+H. P. or model OX-2 engine in the fuselage of the Curtiss JN-4 tractor
+biplane which is so generally used in the United States as a training
+machine. It will be observed that the fuel tank is mounted under a cowl
+directly behind the motor and that it feeds the carburetor by means of
+a flexible fuel pipe. As the tank is mounted higher than the
+carburetor, it will feed that member by gravity. The radiator is mounted
+at the front end of the fuselage and connected to the water piping on
+the motor by the usual rubber hose connections. An oil pan is placed
+under the engine and the top is covered with a hood just as in motor car
+practice. The panels of aluminum are attached to the sides of the
+fuselage and are supplied with doors which open and provide access to
+the carburetor, oil-gauge and other parts of the motor requiring
+inspection. The complete installation with the power plant enclosed is
+given at Fig. 146, and in this it will be observed that the exhaust
+pipes are connected to discharge members that lead the gases above the
+top plane. In the engine shown at Fig. 145 the exhaust flows directly
+into the air at the sides of the machine through short pipes bolted to
+the exhaust gas outlet ports. The installation of the radiator just
+back of the tractor screw insures that adequate cooling will be obtained
+because of the rapid air flow due to the propeller slip stream.
+
+[Illustration: Fig. 146.--Latest Model of Curtiss JN-4 Training Machine,
+Showing Thorough Enclosure of Power Plant and Method of Disposing of the
+Exhaust Gases.]
+
+
+INSTALLATION OF CURTISS OX-2 ENGINE
+
+[Illustration: Fig. 147.--Front View of L. W. F. Tractor Biplane
+Fuselage, Showing Method of Installing Thomas Aeromotor and Method of
+Disposing of Exhaust Gases.]
+
+The following instructions are given in the Curtiss Instruction Book for
+installing the OX-2 engine and preparing it for flights, and taken in
+connection with the very clear illustration presented no difficulty
+should be experienced in understanding the proper installation, and
+mounting of this power plant. The bearers or beds should be 2 inches
+wide by 3 inches deep, preferably of laminated hard wood, and placed
+11-5/8 inches apart. They must be well braced. The six arms of the base
+of the motor are drilled for 3/8-inch bolts, and none but this size
+should he used.
+
+1. _Anchoring the Motor._ Put the bolts in from the bottom, with a large
+washer under the head of each so the head cannot cut into the wood. On
+every bolt use a castellated nut and a cotter pin, or an ordinary nut
+and a lock washer, so the bolt will not work loose. Always set motor in
+place and fasten before attaching any auxiliary apparatus, such as
+carburetor, etc.
+
+2. _Inspecting the Ignition-Switch Wires._ The wires leading from the
+ignition switch must be properly connected--one end to the motor body
+for ground, and the other end to the post on the breaker box of the
+magneto.
+
+3. _Filling the Radiator._ Be sure that the water from the radiator
+fills the cylinder jackets. Pockets of air may remain in the cylinder
+jackets even though the radiator may appear full. Turn the motor over a
+few times by hand after filling the radiator, and then add more water if
+the radiator will take it. The air pockets, if allowed to remain, may
+cause overheating and develop serious trouble when the motor is running.
+
+4. _Filling the Oil Reservoir._ Oil is admitted into the crank-case
+through the breather tube at the rear. It is well to strain all oil put
+into the crank-case. In filling the oil reservoir be sure to turn the
+handle on the oil sight-gauge till it is at right angles with the gauge.
+The oil sight-gauge is on the side of the lower half of the crank-case.
+Put in about 3 gallons of the best obtainable oil, Mobile B recommended.
+It is important to remember that the very best oil is none too good.
+
+5. _Oiling Exposed Moving Parts._ Oil all rocker-arm bearings before
+each flight. A little oil should be applied where the push rods pass
+through the stirrup straps.
+
+6. _Filling the Gasoline Tanks._ Be certain that all connections in the
+gasoline system are tight.
+
+7. _Turning on the Gasoline._ Open the cock leading from the gasoline
+tank to the carburetor.
+
+8. _Charging the Cylinders._ With the ignition switch OFF, prime the
+motor by squirting a little gasoline in each exhaust port and then turn
+the propeller backward two revolutions. Never open the exhaust valve by
+operating the rocker-arm by hand, as the push-rod is liable to come out
+of its socket in the cam follower and bend the rocker-arm when the motor
+turns over.
+
+9. _Starting the Motor by Hand._ Always retard the spark part way, to
+prevent back-firing, by pulling forward the wire attached to the breaker
+box. Failure to so retard the spark in starting may result in serious
+injury to the operator. Turn on the ignition switch with throttle partly
+open; give a quick, strong pull down and outward on the starting crank
+or propeller. As soon as the motor is started advance the spark by
+releasing the retard wire.
+
+10. _Oil Circulation._ Let the motor run at low speed for a few minutes
+in order to establish oil circulation in all bearings. With all parts
+functioning properly, the throttle may be opened gradually for warming
+up before flight.
+
+
+STANDARD S.A.E. ENGINE BED DIMENSIONS
+
+The Society of Automotive Engineers have made efforts to standardize
+dimensions of bed timbers for supporting power plant in an aeroplane.
+Owing to the great difference in length no standardization is thought
+possible in this regard. The dimensions recommended are as follows:
+
+  Distance between timbers           12     in.   14     in.   16 in.
+  Width of bed timbers                1-1/2 in.    1-3/4 in.    2 in.
+  Distance between centers of bolts  13-1/2 in.   15-3/4 in.   18 in.
+
+It will be evident that if any standard of this nature were adopted by
+engine builders that the designers of fuselage could easily arrange
+their bed timbers to conform to these dimensions, whereas it would be
+difficult to have them adhere to any standard longitudinal dimensions
+which are much more easily varied in fuselages than the transverse
+dimensions are. It, however, should be possible to standardize the
+longitudinal positions of the holding down bolts as the engine designer
+would still be able to allow himself considerable space fore-and-aft of
+the bolts.
+
+[Illustration: Fig. 148.--End Elevation of Hall-Scott A-7 Four-Cylinder
+Motor, with Installation Dimensions.]
+
+
+HALL-SCOTT ENGINE INSTALLATION
+
+[Illustration: Fig. 149.--Plan and Side Elevation of Hall-Scott A-7
+Four-Cylinder Airplane Engine, with Installation Dimensions.]
+
+The very thorough manner in which installation diagrams are prepared by
+the leading engine makers leaves nothing to the imagination. The
+dimensions of the Hall-Scott four-cylinder airplane engine are given
+clearly in our inch measurements with the metric equivalents at Figs.
+148 and 149, the former showing a vertical elevation while the latter
+has a plan view and side elevation. The installation of this engine in
+airplanes is clearly shown at Figs. 150 and 151, the former having the
+radiator installed at the front of the motor and having all exhaust
+pipes joined to one common discharge funnel, which deflects the gas over
+the top plane while the latter has the radiator placed vertically above
+the motor at the back end and has a direct exhaust gas discharge to the
+air.
+
+[Illustration: Fig. 150.
+
+CENSORED]
+
+[Illustration: Fig. 151.
+
+CENSORED]
+
+The dimensions of the six-cylinder Hall-Scott motor which is known as
+the type A-5 125 H. P. are given at Fig. 152, which is an end sectional
+elevation, and at Fig. 153, which is a plan view. The dimensions are
+given both in inch sizes and the metric equivalents. The appearance of
+a Hall-Scott six-cylinder engine installed in a fuselage is given at
+Fig. 154, while a diagram showing the location of the engine and the
+various pipes leading to the auxiliary groups is outlined at Fig. 155.
+The following instructions for installing the Hall-Scott power plant
+are reproduced from the instruction book issued by the maker.
+Operating instructions which are given should enable any good mechanic
+to make a proper installation and to keep the engine in good running
+condition.
+
+[Illustration: Fig. 152.
+
+CENSORED]
+
+
+FUEL SYSTEM INSTALLATION
+
+[Illustration: Fig. 153.--Plan View of Hall-Scott Type A-5 125
+Horse-Power Airplane Engine, Showing Installation Dimensions.]
+
+Gasoline giving the best results with this equipment is as follows:
+Gravity 58-62 deg. Baume A. Initial boiling point--Richmond method--102°
+Fahr. Sulphur .014. Calorimetric bomb test 20610 B. T. U. per pound. If
+the gasoline tank is placed in the fuselage below the level of the
+carburetor, a hand pump must be used to maintain air pressure in gas
+tank to force the gasoline to the carburetor. After starting the engine
+the small auxiliary air pump upon the engine will maintain sufficient
+pressure. A-7a and A-5a engines are furnished with a new type auxiliary
+air pump. This should be frequently oiled and care taken so no grit or
+sand will enter which might lodge between the valve and its seat, which
+would make it fail to operate properly. An air relief valve is furnished
+with each engine. It should be screwed into the gas tank and properly
+regulated to maintain the pressure required. This is done by screwing
+the ratchet on top either up or down. If two tanks are used in a plane
+one should be installed in each tank. All air pump lines should be
+carefully gone over quite frequently to ascertain if they are tight.
+Check valves have to be placed in these lines. In some cases the
+gasoline tank is placed above the engine, allowing it to drain by
+gravity to the carburetor. When using this system there should be a drop
+of not less than two feet from the lowest portion of the gasoline tank
+to the upper part of the carburetor float chamber. Even this height
+might not be sufficient to maintain the proper volume of gasoline to the
+carburetor at high speeds. Air pressure is advised upon all tanks to
+insure the proper supply of gasoline. When using gravity feed without
+air pressure be sure to vent the tank to allow circulation of air. If
+gravity tank is used and the engine runs satisfactorily at low speeds
+but cuts out at high speeds the trouble is undoubtedly due to
+insufficient height of the tank above the carburetor. The tank should be
+raised or air pressure system used.
+
+[Illustration: Fig. 154.--Three-Quarter View of Hall-Scott Type A-5 125
+Horse-Power Six-Cylinder Engine, with One of the Side Radiators Removed
+to Show Installation in Standard Fuselage.]
+
+[Illustration: Fig. 155.--Diagram Showing Proper Installation of
+Hall-Scott Type A-5 125 Horse-Power Engine with Pressure Feed Fuel
+Supply System.]
+
+
+IGNITION SWITCHES
+
+Two "DIXIE" switches are furnished with each engine. Both of these
+should be installed in the pilot's seat, one controlling the R. H., and
+the other the L. H. magneto. By shorting either one or the other it can
+be quickly determined if both magnetos, with their respective
+spark-plugs, are working correctly. Care should be taken not to use
+spark-plugs having _special extensions or long protruding points_. Plugs
+giving best results are extremely small with short points.
+
+
+WATER SYSTEMS
+
+A temperature gauge should be installed in the water pipe, coming
+directly from the cylinder nearest the propeller (note illustration
+above). This instrument installed in the radiator cap has not always
+given satisfactory results. This is especially noticeable when the water
+in the radiator becomes low, not allowing it to touch the bulb on the
+moto-meter. For ordinary running, it should not indicate over 150
+degrees Fahr. In climbing tests, however, a temperature of 160 degrees
+Fahr. can be maintained without any ill effects upon the engine. In case
+the engine becomes overheated, the indicator will register above 180
+degrees Fahr., in which case it should be stopped immediately.
+Overheating is most generally caused by retarded spark, excessive carbon
+in the cylinders, insufficient lubrication, improperly timed valves,
+lack of water, clogging of water system in any way which would obstruct
+the free circulation of the water.
+
+Overheating will cause the engine to knock, with possible damaging
+results. Suction pipes should be made out of thin tubing, and run within
+a quarter or an eighth of an inch of each other, so that when a hose is
+placed over the two, it will not be possible to suck together. This is
+often the case when a long rubber hose is used, which causes
+overheating. Radiators should be flushed out and cleaned thoroughly
+quite often. A dirty radiator may cause overheating.
+
+When filling the radiator it is very important to remove the plug on top
+of the water pump until water appears. This is to avoid air pockets
+being formed in the circulating system, which might not only heat up the
+engine, but cause considerable damage. All water pump hoses and
+connections should be tightly taped and shellacked after the engine is
+properly installed in the plane. The greatest care should be taken when
+making engine installation _not_ to use smaller inside diameter hose
+connection than water pump suction end casting. One inch and a quarter
+inside diameter should be used on A-7 and A-5 motors, while nothing less
+than one inch and a half inside diameter hose or tubing on all A-7a and
+A-5a engines. It is further important to have light spun tubing, void of
+any sharp turns, leads from pump to radiator and cylinder water outlet
+to radiator. In other words, the water circulation through the engine
+must be as little restricted as possible. Be sure no light hose is used,
+that will often suck together when engine is started. To thoroughly
+drain the water from the entire system, open the drain cock at the
+lowest side of the water pump.
+
+
+PREPARATIONS TO START ENGINE
+
+Always replenish gasoline tanks through a strainer which is clean. This
+strainer must catch all water and other impurities in the gasoline. Pour
+at least three gallons of fresh oil into the lower crank-case. Oil all
+rocker arms through oilers upon rocker arm housing caps. Be sure
+radiators are filled within one inch of the top.
+
+After all the parts are oiled, and the tanks filled, the following must
+be looked after before starting: See if crank-shaft flange is tight on
+shaft. See if propeller bolts are tight and evenly drawn up. See if
+propeller bolts are wired. See if propeller is trued up to within 1/8".
+
+Every four days the magnetos should be oiled if the engine is in daily
+use.
+
+Every month all cylinder hold-down nuts should be gone over to ascertain
+if they are tight. (Be sure to recotter nuts.)
+
+See if magnetos are bolted on tight and wired.
+
+See if magneto cables are in good condition.
+
+See if rocker arm tappets have a .020" clearance from valve stem when
+valve is seated.
+
+See if tappet clamp screws are tight and cottered.
+
+See if all gasoline, oil, water pipes and connections are in perfect
+condition.
+
+Air on gas line should be tested for leaks.
+
+Pump at least three pounds air pressure into gasoline tank.
+
+After making sure that above rules have been observed, test compression
+of cylinders by turning propeller.
+
+"DO NOT FORGET TO SHORT BOTH MAGNETOS"
+
+Be sure all compression release and priming cocks do not leak
+compression. If they do, replace same with a new one immediately, as
+this might cause premature firing.
+
+Open priming cocks and squirt some gasoline into each.
+
+Close cocks.
+
+Open compression release cocks.
+
+Open throttle slightly.
+
+If using Berling magnetos they should be three-quarters advanced.
+
+If all the foregoing directions have been carefully followed, the engine
+is ready for starting.
+
+In cranking engine either by starting crank, or propeller, it is
+essential to throw it over compression quickly.
+
+Immediately upon starting, close compression release cocks.
+
+When engine is running, advance magnetos.
+
+After it has warmed up, short one magneto and then the other, to be sure
+both magnetos and spark-plugs are firing properly. If there is a miss,
+the fouled plug must be located and cleaned. There is a possibility that
+the jets in the carburetor are stopped up. If this is the case, do not
+attempt to clean same with any sharp instrument. If this is done, it
+might change the opening in the jets, thus spoiling the adjustment. Jets
+and nozzles should be blown out with air or steam.
+
+An open intake or exhaust valve, which might have become sluggish or
+stuck from carbon, might cause trouble. Be sure to remedy this at once
+by using a little coal-oil or kerosene on same, working the valve by
+hand until it becomes free. We recommend using graphite on valve stems
+mixed with oil to guard against sticking or undue wear.
+
+
+INSTALLING ROTARY AND RADIAL CYLINDER ENGINES
+
+[Illustration: Fig. 156.--Diagram Defining Installation of Gnome
+"Monosoupape" Motor in Tractor Biplane. Note Necessary Piping for Fuel,
+Oil, and Air Lines.]
+
+When rotary engines are installed simple steel stamping or "spiders,"
+are attached to the fuselage to hold the fixed crank-shaft. Inasmuch as
+the motor projects clear of the fuselage proper there is plenty of room
+back of the front spider plate to install the auxiliary parts such as
+the oil pump, air pump and ignition magneto and also the fuel and oil
+containers. The diagram given at Fig. 156 shows how a Gnome
+"monosoupape" engine is installed on the anchorage plates and it also
+outlines clearly the piping necessary to convey the oil and fuel and
+also the air-piping needed to put pressure on both fuel and oil tanks to
+insure positive supply of these liquids which may be carried in tanks
+placed lower than the motor in some installations. The diagram given at
+Figs. 157 and 158 shows other mountings of Gnome engines and are
+self-explanatory. The simple mounting possible when the Anzani
+ten-cylinder radial fixed type engine is used given at Fig. 159. The
+front end of the fuselage is provided with a substantial pressed steel
+plate having members projecting from it which may be bolted to the
+longerons. The bolts that hold the two halves of the crank-case together
+project through the steel plate and hold the engine securely to the
+front end of the fuselage.
+
+[Illustration: Fig. 157.--Showing Two Methods of Placing Propeller on
+Gnome Rotary Motor.]
+
+
+PRACTICAL HINTS TO LOCATE ENGINE TROUBLES
+
+[Illustration: Fig. 158.--How Gnome Rotary Motor May Be Attached to
+Airplane Fuselage Members.]
+
+One who is not thoroughly familiar with engine construction will seldom
+locate troubles by haphazard experimenting and it is only by a
+systematic search that the cause can be discovered and the defects
+eliminated. In this chapter the writer proposes to outline some of the
+most common power-plant troubles and to give sufficient advice to enable
+those who are not thoroughly informed to locate them by a logical
+process of elimination. The internal-combustion motor, which is the
+power plant of all gasoline automobiles as well as airplanes, is
+composed of a number of distinct groups, which in turn include distinct
+components. These various appliances are so closely related to each
+other that defective action of any one may interrupt the operation of
+the entire power plant. Some of the auxiliary groups are more necessary
+than others and the power plant will continue to operate for a time even
+after the failure of some important parts of some of the auxiliary
+groups. The gasoline engine in itself is a complete mechanism, but it
+is evident that it cannot deliver any power without some means of
+supplying gas to the cylinders and igniting the compressed gas charge
+after it has been compressed in the cylinders. From this it is patent
+that the ignition and carburetion systems are just as essential parts of
+the power plant as the piston, connecting rod, or cylinder of the motor.
+The failure of either the carburetor or igniting means to function
+properly will be immediately apparent by faulty action of the power
+plant.
+
+[Illustration: Fig. 159.--How Anzani Ten-Cylinder Radial Engine is
+Installed to Plate Securely Attached to Front End of Tractor Airplane
+Fuselage.]
+
+To insure that the motor will continue to operate it is necessary to
+keep it from overheating by some form of cooling system and to supply
+oil to the moving parts to reduce friction. The cooling and lubrication
+groups are not so important as carburetion and ignition, as the engine
+would run for a limited period of time even should the cooling system
+fail or the oil supply cease. It would only be a few moments, however,
+before the engine would overheat if the cooling system was at fault, and
+the parts seize if the lubricating system should fail. Any derangement
+in the carburetor or ignition mechanism would manifest itself at once
+because the engine operation would be affected, but a defect in the
+cooling or oiling system would not be noticed so readily.
+
+The careful aviator will always inspect the motor mechanism before
+starting on a trip of any consequence, and if inspection is carefully
+carried out and loose parts tightened it is seldom that irregular
+operation will be found due to actual breakage of any of the components
+of the mechanism. Deterioration due to natural causes matures slowly,
+and sufficient warning is always given when parts begin to wear so
+satisfactory repairs may be promptly made before serious derangement or
+failure is manifested.
+
+
+A TYPICAL ENGINE STOPPAGE ANALYZED
+
+Before describing the points that may fail in the various auxiliary
+systems it will be well to assume a typical case of engine failure and
+show the process of locating the trouble in a systematic manner by
+indicating the various steps which are in logical order and which could
+reasonably be followed. In any case of engine failure the ignition
+system, motor compression, and carburetor should be tested first. If the
+ignition system is functioning properly one should determine the amount
+of compression in all cylinders and if this is satisfactory the
+carbureting group should be tested. If the ignition system is working
+properly and there is a decided resistance in the cylinders when the
+propeller is turned, proving that there is good compression, one may
+suspect the carburetor.
+
+[Illustration: Fig. 160.--Side Elevation of Thomas 135 Horse-Power
+Airplane Engine, Giving Important Dimensions.]
+
+If the carburetor appears to be in good condition, the trouble may be
+caused by the ignition being out of time, which condition is possible
+when the magneto timing gear or coupling is attached to the armature
+shaft by a taper and nut retention instead of the more positive key or
+taper-pin fastening. It is possible that the inlet manifold may be
+broken or perforated, that the exhaust valve is stuck on its seat
+because of a broken or bent stem, broken or loose cam, or failure of the
+cam-shaft drive because the teeth are stripped from the engine shaft or
+cam-shaft gears; or because the key or other fastening on either gear
+has failed, allowing that member to turn independently of the shaft to
+which it normally is attached. The gasoline feed pipe may be clogged or
+broken, the fuel supply may be depleted, or the shut-off cock in the
+gasoline line may have jarred closed. The gasoline filter may be filled
+with dirt or water which prevents passage of the fuel.
+
+[Illustration: Fig. 161.--Front Elevation of Thomas-Morse 135
+Horse-Power Aeromotor, Showing Main Dimensions.]
+
+The defects outlined above, except the failure of the gasoline supply,
+are very rare, and if the container is found to contain fuel and the
+pipe line to be clear to the carburetor, it is safe to assume the
+vaporizing device is at fault. If fuel continually runs out of the
+mixing chamber the carburetor is said to be flooded. This condition
+results from failure of the shut-off needle to seat properly or from a
+punctured hollow metal float or a gasoline-soaked cork float. It is
+possible that not enough gasoline is present in the float chamber. If
+the passage controlled by the float-needle valve is clogged or if the
+float was badly out of adjustment, this contingency would be probable.
+When the carburetor is examined, if the gasoline level appears to be at
+the proper height, one may suspect that a particle of lint, or dust, or
+fine scale, or rust from the gasoline tank has clogged the bore of the
+jet in the mixing chamber.
+
+If the ignition system and carburetor appear to be in good working
+order, and the hand crank shows that there is no compression in one or
+more of the cylinders, it means some defect in the valve system. If the
+engine is a multiple-cylinder type and one finds poor compression in all
+of the cylinders it may be due to the rare defect of improper valve
+timing. This may be caused by a gear having altered its position on the
+cam-shaft or crank-shaft, because of a sheared key or pin having
+permitted the gear to turn about half of a revolution and then having
+caught and held the gear in place by a broken or jagged end so that
+cam-shaft would turn, but the valves open at the wrong time. If but one
+of the cylinders is at fault and the rest appear to have good
+compression the trouble may be due to a defective condition either
+inside or outside of that cylinder. The external parts may be inspected
+easily, so the following should be looked for: a broken valve, a warped
+valve-head, broken valve-springs, sticking or bent valve-stems, dirt
+under valve-seat, leak at valve-chamber cap or spark-plug gasket.
+Defective priming cock, cracked cylinder head (rarely occurs), leak
+through cracked spark-plug insulation, valve-plunger stuck in the
+guide, lack of clearance between valve-stem end and top of plunger
+caused by loose adjusting screw which has worked up and kept the valve
+from seating. The faulty compression may be due to defects inside the
+motor. The piston-head may be cracked (rarely occurs), piston rings may
+be broken, the slots in the piston rings may be in line, the rings may
+have lost their elasticity or have become gummed in the grooves of the
+piston, or the piston and cylinder walls may be badly scored by a loose
+wrist pin or by defective lubrication. If the motor is a type with a
+separate head it is possible the gasket or packing between the cylinder
+and combustion chamber may leak, either admitting water to the cylinder
+or allowing compression to escape.
+
+[Illustration: Fig. 162.--Front and Side Elevations of Sturtevant
+Airplane Engine, Giving Principal Dimensions to Facilitate
+Installation.]
+
+
+CONDITIONS THAT CAUSE FAILURE OF IGNITION SYSTEM
+
+If the first test of the motor had showed that the compression was as it
+should be and that there were no serious mechanical defects and there
+was plenty of gasoline at the carburetor, this would have demonstrated
+that the ignition system was not functioning properly. If a battery is
+employed to supply current the first step is to take the spark-plugs out
+of the cylinders and test the system by turning over the engine by hand.
+If there is no spark in any of the plugs, this may be considered a
+positive indication that there is a broken main current lead from the
+battery, a defective ground connection, a loose battery terminal, or a
+broken connector. If none of these conditions are present, it is safe to
+say that the battery is no longer capable of delivering current. While
+magneto ignition is generally used on airplane engines, there is apt to
+be some development of battery ignition, especially on engines equipped
+with electric self-starters which are now being experimented with. The
+spark-plugs may be short circuited by cracked insulation or carbon and
+oil deposits around the electrode. The secondary wires may be broken or
+have defective insulation which permits the current to ground to some
+metal part of the fuselage or motor. The electrodes of the spark-plug
+may be too far apart to permit a spark to overcome the resistance of the
+compressed gas, even if a spark jumps the air space, when the plug is
+laid on the cylinder.
+
+If magnetos are fitted as is usually the case at present and a spark is
+obtained between the points of the plug and that device or the wire
+leading to it from the magneto is in proper condition, the trouble is
+probably caused by the magneto being out of time. This may result if the
+driving gear is loose on the armature-shaft or crank-shaft, and is a
+rare occurrence. If no spark is produced at the plugs the secondary wire
+may be broken, the ground wire may make contact with some metallic
+portion of the chassis before it reaches the switch, the carbon
+collecting brushes may be broken or not making contact, the contact
+points of the make-and-break device may be out of adjustment, the wiring
+may be attached to wrong terminals, the distributor filled with metallic
+particles, carbon, dust or oil accumulations, the distributor contacts
+may not be making proper connection because of wear and there may be a
+more serious derangement, such as a burned out secondary winding or a
+punctured condenser.
+
+If the motor runs intermittently, _i.e._, starts and runs only a few
+revolutions, aside from the conditions previously outlined, defective
+operation may be due to seizing between parts because of insufficient
+oil or deficient cooling, too much oil in the crank-case which fouls the
+cylinder after the crank-shaft has revolved a few turns, and
+derangements in the ignition or carburetion systems that may be easily
+remedied. There are a number of defective conditions which may exist in
+the ignition group, that will result in "skipping" or irregular
+operation and the following points should be considered first: weak
+source of current due to worn out dry cells or discharged storage
+batteries; weak magnets in magneto, or defective contacts at magneto;
+dirt in magneto distributor or poor contact at collecting brushes. Dirty
+or cracked insulator at spark-plug will cause short circuit and can
+only be detected by careful examination. The following points should
+also be checked over when the plug is inspected: Excessive space between
+electrodes, points too close together, loose central electrodes, or
+loose point on plug body, soot or oil particles between electrodes, or
+on the surface of the insulator, cracked insulator, oil or water on
+outside of insulator. Short circuits in the condenser or internal wiring
+of induction coils or magnetos, which are fortunately not common, can
+seldom be remedied except at the factory where these devices were made.
+If an engine stops suddenly and the defect is in the ignition system the
+trouble is usually never more serious than a broken or loose wire. This
+may be easily located by inspecting the wiring at the terminals.
+Irregular operation or misfiring is harder to locate because the trouble
+can only be found after the many possible defective conditions have been
+checked over, one by one.
+
+
+COMMON DEFECTS IN FUEL SYSTEMS
+
+Defective carburetion often causes misfiring or irregular operation. The
+common derangement of the components of the fuel system that are common
+enough to warrant suspicion and the best methods for their location
+follows: First, disconnect the feed pipe from the carburetor and see if
+the gasoline flows freely from the tank. If the stream coming out of the
+pipe is not the full size of the orifice it is an indication that the
+pipe is clogged with dirt or that there is an accumulation of rust,
+scale, or lint in the strainer screens of the filter. It is also
+possible that the fuel shut-off valve may be wholly or partly closed. If
+the gasoline flows by gravity the liquid may be air bound in the tank,
+while if a pressure-feed system is utilized the tank may leak so that it
+does not retain pressure; the check valve retaining the pressure may be
+defective or the pipe conveying the air or gas under pressure to the
+tank may be clogged.
+
+If the gasoline flows from the pipe in a steady stream the carburetor
+demands examination. There may be dirt or water in the float chamber,
+which will constrict the passage between the float chamber and the spray
+nozzle, or a particle of foreign matter may have entered the nozzle and
+stopped up the fine holes therein. The float may bind on its guide, the
+needle valve regulating the gasoline-inlet opening in bowl may stick to
+its seat. Any of the conditions mentioned would cut down the gasoline
+supply and the engine would not receive sufficient quantities of gas.
+The air-valve spring may be weak or the air valve broken. The
+gasoline-adjusting needle may be loose and jar out of adjustment, or the
+air-valve spring-adjusting nuts may be such a poor fit on the stem that
+adjustments will not be retained. These instructions apply only to
+carburetors having air valves and mixture regulating means which are
+used only in rare instances in airplane work. Air may leak in through
+the manifold, due to a porous casting, or leaky joints in a built up
+form and dilute the mixture. The air-intake dust screen may be so
+clogged with dirt and lint that not enough air will pass through the
+mesh. Water or sediment in the gasoline will cause misfiring because the
+fuel feed varies when the water or dirt constricts the standpipe bore.
+
+It is possible that the carburetor may be out of adjustment. If clouds
+of black smoke are emitted at the exhaust pipe it is positive indication
+that too much gasoline is being supplied the mixture and the supply
+should be cut down by screwing in the needle valve on types where this
+method of regulation is provided, and by making sure that the fuel level
+is at the proper height, or that the proper nozzle is used in those
+forms where the spray nozzle has no means of adjustment. If the mixture
+contains too much air there will be a pronounced popping back in the
+carburetor. This may be overcome by screwing in the air-valve adjustment
+so the spring tension is increased or by slightly opening up the
+gasoline-supply regulation needle. When a carburetor is properly
+adjusted and the mixture delivered the cylinder burns properly, the
+exhaust gas will be clean and free from the objectionable odor present
+when gasoline is burned in excess.
+
+The character of combustion may be judged by the color of the flame
+which issues from it when the engine is running with an open throttle
+after nightfall. If the flame is red, it indicates too much gasoline. If
+yellowish, it shows an excess of air, while a properly proportioned
+mixture will be evidenced by a pronounced blue flame, such as given by a
+gas-stove burner.
+
+The Duplex Model O. D. Zenith carburetor used upon most of the six- and
+eight-cylinder airplane engines consists of a single float chamber, and
+a single air intake, joined to two separate and distinct spray nozzles,
+venturi and idling adjustments. It is to be noted that as the carburetor
+barrels are arranged side by side, both valves are mounted on the same
+shaft, and work in unison through a single operating lever. It is not
+necessary to alter their position. In order to make the engine idle
+well, it is essential that the ignition, especially the spark-plugs,
+should be in good condition. The gaskets between carburetor and
+manifold, and between manifold and cylinders should be absolutely
+air-tight. The adjustment for low speed on the carburetor is made by
+turning in or out the two knurled screws, placed one on each side of the
+float chamber. After starting the engine and allowing it to become
+thoroughly warmed, one side of the carburetor should be adjusted so that
+the three cylinders it affects fire properly at low speed. The other
+side should be adjusted in the same manner until all six cylinders fire
+perfectly at low speed. As the adjustment is changed on the knurled
+screw a difference in the idling of the engine should be noticed. If the
+engine begins to run evenly or speeds up it shows that the mixture
+becomes right in its proportion.
+
+Be sure the butterfly throttle is closed as far as possible by screwing
+out the stop screw which regulates the closed position for idling. Care
+should be taken to have the butterfly held firmly against this stop
+screw at all times while idling engine. If three cylinders seem to run
+irregularly after changing the position of the butterfly, still another
+adjustment may have to be made with the knurled screw. Unscrewing this
+makes the mixture leaner. Screwing in closes off some of the air supply
+to the idling jet, making it richer. After one side has been made to
+idle satisfactorily repeat the same procedure with the opposite three
+cylinders. In other words, each side should be idled independently to
+about the same speed.
+
+Remember that the main jet and compensating jet have no appreciable
+effect on the idling of the engine. The idling mixture is drawn directly
+through the opening determined by the knurled screw and enters the
+carburetor barrel through the small hole at the edge of each butterfly.
+This is called the priming hole and is only effective during idling.
+Beyond that point the suction is transferred to the main jet and
+compensator, which controls the power of the engine beyond the idling
+position of the throttle.
+
+
+DEFECTS IN OILING SYSTEMS
+
+While troubles existing in the ignition or carburetion groups are
+usually denoted by imperfect operation of the motor, such as lost power,
+and misfiring, derangements of the lubrication or cooling systems are
+usually evident by overheating, diminution in engine capacity, or noisy
+operation. Overheating may be caused by poor carburetion as much as by
+deficient cooling or insufficient oiling. When the oiling group is not
+functioning as it should the friction between the motor parts produces
+heat. If the cooling system is in proper condition, as will be evidenced
+by the condition of the water in the radiator, and the carburetion group
+appears to be in good condition, the overheating is probably caused by
+some defect in the oiling system.
+
+The conditions that most commonly result in poor lubrication are:
+Insufficient oil in the engine crank-case or sump, broken or clogged oil
+pipes, screen at filter filled with lint or dirt, broken oil pump, or
+defective oil-pump drive. The supply of oil may be reduced by a
+defective inlet or discharge-check valve at the mechanical oiler or worn
+pumps. A clogged oil passage or pipe leading to an important bearing
+point will cause trouble because the oil cannot get between the working
+surfaces. It is well to remember that much of the trouble caused by
+defective oiling may be prevented by using only the best grades of
+lubricant, and even if all parts of the oil system are working properly,
+oils of poor quality will cause friction and overheating.
+
+
+DEFECTS IN COOLING SYSTEMS OUTLINED
+
+Cooling systems are very simple and are not liable to give trouble as a
+rule if the radiator is kept full of clean water and the circulation is
+not impeded. When overheating is due to defective cooling the most
+common troubles are those that impede water circulation. If the radiator
+is clogged or the piping of water jackets filled with rust or sediment
+the speed of water circulation will be slow, which will also be the case
+if the water pump or its driving means fail. Any scale or sediment in
+the water jackets or in the piping or radiator passages will reduce the
+heat conductivity of the metal exposed to the air, and the water will
+not be cooled as quickly as though the scale was not present.
+
+The rubber hose often used in making the flexible connections demanded
+between the radiator and water manifolds of the engine may deteriorate
+inside and particles of rubber hang down that will reduce the area of
+the passage. The grease from the grease cups mounted on the pump-shaft
+bearing to lubricate that member often finds its way into the water
+system and rots the inner walls of the rubber hose, this resulting in
+strips of the partly decomposed rubber lining hanging down and
+restricting the passage. The cooling system is prone to overheat after
+antifreezing solutions of which calcium chloride forms a part have been
+used. This is due to the formation of crystals of salt in the radiator
+passages or water jackets, and these crystals can only be dissolved by
+suitable chemical means, or removed by scraping when the construction
+permits.
+
+Overheating is often caused by some condition in the fuel system that
+produces too rich or too lean mixture. Excess gasoline may be supplied
+if any of the following conditions are present: Bore of spray nozzle or
+standpipe too large, auxiliary air-valve spring too tight, gasoline
+level too high, loose regulating valve, fuel-soaked cork float,
+punctured sheet-metal float, dirt under float control shut-off valve or
+insufficient air supply because of a clogged air screen. If pressure
+feed is utilized there may be too much pressure in the tank, or the
+float controlled mechanism operating the shut-off in the float bowl of
+the carburetor may not act quickly enough.
+
+
+SOME CAUSES OF NOISY OPERATION
+
+There are a number of power-plant derangements which give positive
+indication because of noisy operation. Any knocking or rattling sounds
+are usually produced by wear in connecting rods or main bearings of the
+engine, though sometimes a sharp metallic knock, which is very much the
+same as that produced by a loose bearing, is due to carbon deposits in
+the cylinder heads, or premature ignition due to advanced spark-time
+lever. Squeaking sounds invariably indicate dry bearings, and whenever
+such a sound is heard it should be immediately located and oil applied
+to the parts thus denoting their dry condition. Whistling or blowing
+sounds are produced by leaks, either in the engine itself or in the gas
+manifolds. A sharp whistle denotes the escape of gas under pressure and
+is usually caused by a defective packing or gasket that seals a portion
+of the combustion chamber or that is used for a joint as the exhaust
+manifold. A blowing sound indicates a leaky packing in crank-case.
+Grinding noises in the motor are usually caused by the timing gears and
+will obtain if these gears are dry or if they have become worn. Whenever
+a loud knocking sound is heard careful inspection should be made to
+locate the cause of the trouble. Much harm may be done in a few minutes
+if the engine is run with loose connecting rod or bearings that would be
+prevented by taking up the wear or looseness between the parts by some
+means of adjustment.
+
+
+BRIEF SUMMARY OF HINTS FOR STARTING ENGINE
+
+First make sure that all cylinders have compression. To ascertain this,
+open pet cocks of all cylinders except the one to be tested, crank over
+motor and see that a strong opposition to cranking is met with once in
+two revolutions. If motor has no pet cocks, crank and notice that
+oppositions are met at equal distances, two to every revolution of the
+starting crank in a four-cylinder motor. If compression is lacking,
+examine the parts of the cylinder or cylinders at fault in the following
+order, trying to start the motor whenever any one fault is found and
+remedied. See that the valve push rods or rocker arms do not touch valve
+stems for more than approximately 1/2 revolution in every 2 revolutions,
+and that there is not more than .010 to .020 inch clearance between them
+depending on the make of the motor. Make sure that the exhaust valve
+seats. To determine this examine the spring and see that it is connected
+to the valve stem properly. Take out valve and see that there is no
+obstruction, such as carbon, on its seat. See that valve works freely in
+its guide. Examine inlet valve in same manner. Listen for hissing sound
+while cranking motor for leaks at other places.
+
+Make sure that a spark occurs in each cylinder as follows: If magneto or
+magneto and battery with non-vibrating coil is used: Disconnect wire
+from spark-plug, hold end about 1/8 inch from cylinder or terminal of
+spark-plug. Have motor cranked briskly and see if spark occurs. Examine
+adjustment of interrupter points. See that wires are placed correctly
+and not short circuited. Take out spark-plug and lay it on the cylinder,
+being careful that base of plug only touches the cylinder and that
+ignition wire is connected. Have motor cranked briskly and see if spark
+occurs. Check timing of magneto and see that all brushes are making
+contact.
+
+See if there is gasoline in the carburetor. See that there is gasoline
+in the tank. Examine valve at tank. Prime carburetor and see that spray
+nozzle passage is clear. Be sure throttle is open. Prime cylinders by
+putting about a teaspoonful of gasoline in through pet cock or
+spark-plug opening. Adjust carburetor if necessary.
+
+
+LOCATION OF ENGINE TROUBLES MADE EASY
+
+The following tabulation has been prepared and originated by the writer
+to outline in a simple manner the various troubles and derangements that
+interfere with efficient internal-combustion engine action. The parts
+and their functions are practically the same in all gas or gasoline
+engines of the four-cycle type, and the general instructions given apply
+just as well to all hydro-carbon engines, even if the parts differ in
+form materially. The essential components are clearly indicated in the
+many part sectional drawings in this book so they may be easily
+recognized. The various defects that may materialize are tabulated in a
+manner that makes for ready reference, and the various defective
+conditions are found opposite the part affected, and under a heading
+that denotes the main trouble to which the others are contributing
+causes. The various symptoms denoting the individual troubles outlined
+are given to facilitate their recognition in a positive manner.
+
+Brief note is also made of the remedies for the restoration of the
+defective part or condition. It is apparent that a table of this
+character is intended merely as a guide, and it is a compilation of
+practically all the known troubles that may materialize in gas-engine
+operation. While most of the defects outlined are common enough to
+warrant suspicion, they will never exist in an engine all at the same
+time, and it will be necessary to make a systematic search for such of
+those as exist.
+
+To use the list advantageously, it is necessary to know one main trouble
+easily recognized. For example, if the power plant is noisy, look for
+the possible troubles under the head of Noisy Operation; if it lacks
+capacity, the derangement will undoubtedly be found under the head of
+Lost Power. It is assumed in all cases that the trouble exists in the
+power plant or its components, and not in the auxiliary members of the
+ignition, carburetion, lubrication, or cooling systems. The novice and
+student will readily recognize the parts of the average aviation engine
+by referring to the very complete and clearly lettered illustrations of
+mechanism given in many parts of this treatise.
+
+
+LOST POWER AND OVERHEATING
+
+  ------------------+------------------+------------------+--------------------
+   PART AFFECTED    |NATURE OF TROUBLE |   SYMPTOMS AND   |      REMEDY
+                    |                  |     EFFECTS      |
+  ------------------+------------------+------------------+--------------------
+  Water Pipe Joint. |Loose.            |Loss of water,    |Tighten bolts,
+                    |                  |heating.          |replace gaskets.
+                    |                  |                  |
+  Spark Plug.       |Leakage in        |Loss of power.    |Replace insulation
+                    |threads,          |Hissing caused by |if defective, screw
+                    |insulation,       |escaping gas.     |down tighter.
+                    |packing.          |                  |
+                    |                  |                  |
+  Compression       |Leak in threads.  |Loss of power.    |Tighten if loose.
+  Release Cock.     |Leak in fitting.  |Whistling or      |Grind fitting to
+                    |                  |hissing.          |new seating in
+                    |                  |                  |body.
+                    |                  |                  |
+  Combustion        |Crack or blowhole.|Loss of compres-  |Fill by welding.
+  Chamber.          |Roughness. Carbon |sion. Preignition.|Smooth out
+                    |deposits. Sharp   |                  |roughness. Scrape
+                    |edges.            |                  |out or dissolve
+                    |                  |                  |carbon.
+                    |                  |                  |
+  Valve Chamber Cap.|Leak in threads.  |Loss of compres-  |Remove. Apply pipe
+                    |Defective gasket. |sion. Hissing.    |compound to threads
+                    |                  |                  |and replace. Use
+                    |                  |                  |new gasket or
+                    |                  |                  |packing.
+                    |                  |                  |
+  Valve Head.       |Warped. Scored or |Loss of compres-  |True up in lathe.
+                    |pitted. Carbon-   |sion.             |Grind to seat.
+                    |ized. Covered with|                  |Scrape off. Smooth
+                    |scale. Loose on   |                  |with emery cloth.
+                    |stem (two-piece   |                  |Tighten by
+                    |valves only).     |                  |riveting.
+                    |                  |                  |
+  Valve Seat.       |Warped or pitted. |Loss of compres-  |Use reseating
+                    |Covered with car- |sion.             |reamer. Clean off
+                    |bon. Foreign mat- |                  |and grind valve to
+                    |ter between valve |                  |seat.
+                    |and seat.         |                  |
+                    |                  |                  |
+  Valve Stem.       |Covered with      |Valve does not    |Clean with emery
+                    |scale. Bent. Bind-|close. Loss of    |cloth; straighten.
+                    |ing in guide.     |compression.      |True up and smooth
+                    |Stuck in guide.   |                  |off. free with
+                    |                  |                  |kerosene.
+                    |                  |                  |
+  Valve Stem Guide. |Burnt or rough.   |Valve may stick.  |Clean out hole.
+                    |Loose in valve    |Action irregular. |Screw in tighter.
+                    |chamber.          |                  |
+                    |                  |                  |
+  Valve Spring.     |Weak or broken.   |Valve does not    |
+                    |                  |close.            |
+                    |                  |                  |
+  Valve Operating   |Loose in guide.   |Valve action poor.|Replace with new.
+  Plunger.          |Too much clearance|Lift insufficient.|Adjust screw closer.
+                    |between valve     |                  |
+                    |stem.             |                  |
+                    |                  |                  |
+  Valve Lift Ad-    |Threads stripped. |Poor valve action.|Replace with new.
+  justing Screw.    |Too near valve.   |                  |Adjust with proper
+                    |Too far from      |                  |reference to valve
+                    |valve.            |                  |stem.
+                    |                  |                  |
+  Valve Lift Cam.   |Worn cam contour. |Not enough valve  |Replace with new.
+                    |Loose on shaft.   |lift. Will not    |Replace pins or
+                    |Out of time.      |lift valve. Valve |keys. Set to open
+                    |                  |opens at wrong    |properly.
+                    |                  |time.             |
+                    |                  |                  |
+  Cam-shaft.        |Sprung or twisted.|Valves out of     |Straighten.
+                    |                  |time.             |
+                    |                  |                  |
+  Cam-shaft Bushing.|Worn.             |Not enough valve  |Replace.
+                    |                  |lift.             |
+                    |                  |                  |
+  Cam-shaft Drive   |Loose on shaft.   |Irregular valve   |Fasten securely.
+  Gear.             |Out of time. Worn |action.           |Time properly.
+                    |or broken teeth.  |                  |Replace with new.
+                    |                  |                  |
+  Cam Fastenings.   |Worn or broken.   |Valves out of     |Replace with new.
+                    |                  |time.             |
+                    |                  |                  |
+  Cylinder Wall.    |Scored, gas leaks.|Poor compression. |Grind out bore.
+                    |Poor lubrication  |Overheating.      |Repair oiling
+                    |causes friction.  |                  |system.
+                    |                  |                  |
+  Piston.           |Binds in cylinder.|Overheating. Poor |Lap off excess
+                    |Walls scored. Worn|compression.      |metal. Replace with
+                    |out of round.     |                  |new.
+                    |                  |                  |
+  Piston Rings.     |Loss of spring.   |Loss of compres-  |Peen ring or
+                    |Loose in grooves. |sion. Gas blows   |replace. Fit new
+                    |Scored. Worn or   |by.               |rings. Grind smooth.
+                    |broken. Slots in  |                  |Replace. Turn slots
+                    |line.             |                  |apart.
+                    |                  |                  |
+                    |Carbon in grooves.|Overheating be-   |Remove deposits.
+                    |Insufficient open-|cause of friction.|File slot. Grind or
+                    |ing. Binding on   |                  |lap to fit cylinder
+                    |cylinder.         |                  |bore.
+                    |                  |                  |
+  Wristpin.         |Loose, scores     |Loss of compres-  |Fasten securely.
+                    |cylinder.         |sion.             |Replace cylinder if
+                    |                  |                  |groove is deep.
+                    |                  |                  |
+  Crank-shaft.      |Scored or rough on|Overheating be-   |Smooth up.
+                    |journals. Sprung. |cause of friction.|Straighten.
+                    |                  |                  |
+  Crank Bearings.   |Adjusted too      |Overheating be-   |Adjust freely, clean
+  Main Bearings.    |tight. Defective  |cause of friction.|out oil holes and
+                    |oiling. Brasses   |                  |enlarge oil grooves.
+                    |burned.           |                  |
+                    |                  |                  |
+  Oil Sump.         |Insufficient oil. |Overheating.      |Replenish supply.
+                    |Poor lubricant.   |                  |Use best oil. Wash
+                    |Dirty oil.        |                  |out with kerosene;
+                    |                  |                  |put in clean oil.
+                    |                  |                  |
+  Water Space. Water|Clogged with sedi-|Overheating.      |Dissolve foreign
+  Pipes.            |ment or scale.    |                  |matter and remove.
+                    |                  |                  |
+  Piston Head.      |Cracked (rare).   |Loss of compres-  |Weld by autogenous
+                    |Carbon deposits.  |sion. Preignition.|process. Scrape off
+                    |                  |                  |carbon accumula-
+                    |                  |                  |tions.
+  ------------------+------------------+------------------+--------------------
+
+
+NOISY OPERATION OF POWER PLANT
+
+  ------------------+------------------+------------------+--------------------
+   PART AFFECTED    |NATURE OF TROUBLE |   CHARACTER OF   |      REMEDY
+                    |                  |      NOISE       |
+  ------------------+------------------+------------------+--------------------
+  Compression Re-   |Leakage.          |Hissing.          |Previously given.
+  lease Cock.       |                  |                  |
+                    |                  |                  |
+  Spark Plug.       |Leakage.          |Hissing.          |Previously given.
+                    |                  |                  |
+  Valve Chamber Cap.|Leakage.          |Hiss or whistle.  |Previously given.
+                    |                  |                  |
+  Combustion        |Carbon deposits.  |Knocking.         |Previously given.
+  Chamber.          |                  |                  |
+                    |                  |                  |
+  Inlet Valve Seat. |Defects previously|Popping in carbu- |Previously given.
+                    |given.            |retor.            |
+                    |                  |                  |
+  Valve Head.       |Loose on stem.    |Clicking.         |Previously given.
+                    |                  |                  |
+  Valve Stem. Valve |Wear or looseness.|Rattle or click-  |Previously given.
+  Stem Guide.       |                  |ing.              |
+                    |                  |                  |
+  Inlet Valve.      |Closes too late.  |Blowback in carbu-|Previously given.
+                    |Opens too early.  |retor.            |
+                    |                  |                  |
+  Valve Spring.     |Weak or broken.   |Blowback in carbu-|Previously given.
+                    |                  |retor.            |
+                    |                  |                  |
+  Cylinder Casting. |Retaining bolts   |Sharp metallic    |Tighten bolts. Round
+                    |loose. Piston     |knock.            |edges of  piston
+                    |strikes at upper  |                  |top.
+                    |end.              |                  |
+                    |                  |                  |
+  Cylinder Wall.    |Scored.           |Hissing.          |Previously given.
+                    |                  |                  |
+  Valve Stem        |Too much.         |Clicking. Blowback|Previously given.
+  Clearance.        |Too little (inlet |in carburetor.    |
+                    |valve).           |                  |
+                    |                  |                  |
+  Valve Operating   |Looseness.        |Rattle or click-  |Previously given.
+  Plunger. Plunger  |                  |ing.              |
+  Guide.            |                  |                  |
+                    |                  |                  |
+  Timing Gears.     |Loose on fasten-  |Metallic knock.   |Previously given.
+                    |ings. Worn teeth. |Rattle. Grinding. |
+                    |                  |                  |
+  Cylinder or       |No oil, or poor   |Grinding.         |Repair oil system.
+  Piston.           |lubricant.        |                  |
+                    |                  |                  |
+  Cam.              |Loose on shaft.   |Metallic knock.   |Previously given.
+                    |Worn contour.     |                  |
+                    |                  |                  |
+  Cam-shaft Bearing.|Looseness or wear.|Slight knock.     |Previously given.
+                    |                  |                  |
+  Cam Fastening.    |Looseness.        |Clicking.         |Previously given.
+                    |                  |                  |
+  Piston.           |Binding in cylin- |Grinding or dull  |Previously given.
+                    |der. Worn oval,   |squeak. Dull      |
+                    |causes side slap  |hammering.        |
+                    |in cylinder.      |                  |
+                    |                  |                  |
+  Piston Head.      |Carbon deposits.  |Knocking.         |Previously given.
+                    |                  |                  |
+  Piston Rings.     |Defective oiling. |Squeaking. Hiss-  |Previously given.
+                    |Leakage. Binding  |ing. Grinding.    |
+                    |in cylinder.      |                  |
+                    |                  |                  |
+  Wrist-pin.        |Loose in piston.  |Dull metallic     |Replace with new
+                    |Worn.             |knock.            |member.
+                    |                  |                  |
+  Connecting Rod.   |Wear in upper     |Distinct knock.   |Adjust or replace.
+                    |bushing. Wear at  |                  |Scrape and fit. Use
+                    |crank-pin. Side   |                  |longer wrist-pin
+                    |play in piston.   |                  |bushing.
+                    |                  |                  |
+  Crank Bearings.   |Looseness. Exces- |Metallic knock.   |Refit bearings.
+                    |sive end play.    |Intermittent      |Longer bushings
+                    |Binding, fitted   |knock. Squeaking. |needed. Insert shims
+                    |too tight.        |                  |to allow more play.
+                    |                  |                  |
+  Main Bearings.    |Looseness. Defec- |Metallic knock.   |Fit brasses closer
+                    |tive lubrication. |Squeaking.        |to shaft. Clean out
+                    |                  |                  |oil holes and
+                    |                  |                  |grooves.
+                    |                  |                  |
+  Connecting Rod    |Loose.            |Sharp knock.      |Tighten.
+  Bolts. Main       |                  |                  |
+  Bearing Bolts.    |                  |                  |
+                    |                  |                  |
+  Crank-shaft.      |Defective oiling. |Squeaking.        |Previously given.
+                    |                  |                  |
+  Engine Base.      |Loose on frame.   |Sharp pounding.   |Tighten bolts.
+                    |                  |                  |
+  Lower Half Crank- |Bolts loose.      |Knocking.         |Tighten bolts.
+  case.             |                  |                  |
+                    |                  |                  |
+  Fly-wheel.        |Loose on crank-   |Very sharp knock. |Tighten retention
+                    |shaft.            |                  |bolts or fit new
+                    |                  |                  |keys.
+                    |                  |                  |
+  Oil Sump.         |Oil level too low.|Grinding and      |Replenish with best
+                    |Poor lubricant.   |squeak in all     |cylinder oil.
+                    |                  |bearings.         |
+                    |                  |                  |
+  Valve Plunger Re- |Looseness.        |Clicking.         |Tighten nuts.
+  tention Stirrups. |                  |                  |
+                    |                  |                  |
+  Fan.              |Blade loose. Blade|Clicking or       |Tighten. Bend back.
+                    |strikes cooler.   |rattle.           |
+                    |                  |                  |
+  Exhaust Pipe      |Leakage.          |Sharp hissing.    |Tighten or use new
+  Joints.           |                  |                  |gasket.
+                    |                  |                  |
+  Crank-case        |Leakage.          |Blowing sound.    |Use new packing.
+  Packing.          |                  |                  |Tighten bolts.
+                    |                  |                  |
+  Water Pipe.       |Leaks. Loss of    |Pounding because  |Previously given.
+                    |water. Clogged    |engine heats.     |
+                    |with sediment.    |                  |
+                    |                  |                  |
+  Water Jacket.     |Clogged with sedi-|Knocking because  |Dissolve scale and
+                    |ment. Walls       |engine heats.     |flush out water
+                    |covered with      |                  |space with water
+                    |scale.            |                  |under pressure.
+--------------------+------------------+------------------+--------------------
+
+
+"SKIPPING" OR IRREGULAR OPERATION
+
+  ------------------+------------------+------------------+--------------------
+   PART AFFECTED    |NATURE OF TROUBLE |   SYMPTOMS AND   |      REMEDY
+                    |                  |     EFFECTS      |
+  ------------------+------------------+------------------+--------------------
+  Compression Relief|Leak in threads or|Dilutes mixture   |Screw down tighter.
+  Cock.             |spigot.           |with air, causes  |Grind spigot to seat
+                    |                  |blowback.         |with emery.
+                    |                  |                  |
+  Spark-Plug.       |Leak in threads.  |Dilutes mixture.  |Screw down tighter.
+                    |Defective gasket. |Allows short      |Replace with new.
+                    |Cracked insulator.|circuit. No spark.|Set points 1/64"
+                    |Points too near.  |                  |apart for magneto,
+                    |Points covered    |                  |1/32" for battery
+                    |with carbon. Too  |                  |spark.
+                    |much air gap.     |                  |
+                    |                  |                  |
+  Valve Chamber Cap.|Leak in threads.  |Dilutes mixture by|Previously given.
+                    |Defective gasket. |allowing air to   |
+                    |                  |enter cylinder on |
+                    |                  |suction stroke.   |
+                    |                  |                  |
+  Combustion        |Carbon deposits.  |Preignition.      |Scrape out.
+  Chamber.          |                  |                  |
+                    |                  |                  |
+  Valve Head.       |Warped or pitted. |Dilutes charge    |Previously given.
+                    |Loose on stem.    |with poor air or  |
+                    |                  |gas.              |
+                    |                  |                  |
+  Valve Stem.       |Binding in guide. |Irregular valve   |Previously given.
+                    |Sticking.         |action.           |
+                    |                  |                  |
+  Valve Seat.       |Scored or warped. |Gas leak, poor    |Previously given.
+                    |Cracked. Covered  |mixture. Poor com-|
+                    |with scale. Dirt  |pression. Valve   |
+                    |under valve.      |will not close.   |
+                    |                  |                  |
+  Induction Pipe.   |Leak at joints.   |Mixture diluted   |Stop all leaks.
+                    |Crack or blowhole.|with excess air.  |
+                    |                  |                  |
+  Inlet Valve.      |Closes too late.  |Blowback in carbu-|Time properly.
+                    |Opens too early.  |retor.            |
+                    |                  |                  |
+  Exhaust Valve.    |Opens too late.   |Retention of burnt|Time properly.
+                    |Closes too early. |gas dilutes       |
+                    |                  |charge.           |
+                    |                  |                  |
+  Valve Stem Guide. |Bent or carbon-   |Causes valve to   |Previously given.
+                    |ized.             |stick.            |
+                    |                  |                  |
+  Inlet Valve Stem  |Worn, stem loose. |Air drawn in on   |Bush guide or use
+  Guide.            |                  |suction thins gas.|new member.
+                    |                  |                  |
+  Valve Spring.     |Weakened or       |Irregular action. |Use new spring.
+                    |broken.           |                  |
+                    |                  |                  |
+  Valve Stem        |Too little. Too   |Valve will not    |Adjust gap .009"
+  Clearance.        |much.             |shut. Valve opens |inlet, .010"
+                    |                  |late, closes      |exhaust.
+                    |                  |early.            |
+  Valve Spring      |Broken.           |Releases spring.  |Replace.
+  Collar Key.       |                  |                  |
+                    |                  |                  |
+  Cam.              |Worn cam contour. |Valve lift re-    |Previously given.
+                    |Loose on shaft.   |duced. Does not   |
+                    |Out of time.      |lift valve. Valves|
+                    |                  |operate at wrong  |
+                    |                  |time.             |
+                    |                  |                  |
+  Cam-shaft Bearing.|Looseness or wear.|Valve timing      |Replace.
+                    |                  |altered. Valve    |
+                    |                  |lift decreased.   |
+                    |                  |                  |
+  Cam-shaft.        |Twisted.          |Valves out of     |Previously given.
+                    |                  |time.             |
+                    |                  |                  |
+  Cam Fastening.    |Worn or broken.   |Valve action      |Replace with new.
+                    |                  |irregular.        |
+                    |                  |                  |
+  Valve Operating   |Loose in guide.   |Alters valve      |Replace with new.
+  Plunger.          |                  |timing.           |
+                    |                  |                  |
+  Valve Plunger     |Wear in bore.     |Alters valve      |Replace or bush.
+  Guide.            |Loose on engine   |timing.           |Fasten securely.
+                    |base.             |                  |
+                    |                  |                  |
+  Timing Gears.     |Not properly      |Valves out of     |Retime properly.
+                    |meshed. Loose on  |time. Valves do   |Fasten to shaft.
+                    |shaft.            |not operate.      |
+                    |                  |                  |
+  Piston.           |Walls scored.     |Leakage of gas.   |Smooth up if
+                    |                  |                  |possible.
+                    |                  |                  |
+  Piston Head.      |Carbon deposits.  |Cause premature   |Previously given.
+                    |Crack or blowhole |ignition.         |
+                    |(rare).           |                  |
+                    |                  |                  |
+  Piston Rings.     |No spring. Loose  |Leakage weakens   |Previously given.
+                    |in grooves. Worn  |suction.          |
+                    |or broken.        |                  |
+                    |                  |                  |
+  Cylinder Wall.    |Scored by wrist-  |Gas leaks by. Poor|Previously given.
+                    |pin. Scored by    |suction.          |
+                    |lack of oil.      |                  |
+  ------------------+------------------+------------------+--------------------
+
+
+IGNITION SYSTEM TROUBLES ONLY
+
+
+_Motor Will Not Start or Starts Hard_
+
+  Loose Battery Terminal.
+  Magneto Ground Wire Shorted.
+  Magneto Defective (No Spark at Plugs).
+  Broken Spark Plug Insulation.
+  Carbon Deposits or Oil Between Plug Points.
+  Spark-Plug Points Too Near Together or Far Apart.
+  Wrong Cables to Plugs.
+  Short Circuited Secondary Cable.
+  Broken Secondary Cable.
+  Dry Battery Weak.            }
+  Storage Battery Discharged.  } Battery Systems
+  Poor Contact at Timer.       } Only.
+  Timer Points Dirty.          }
+  Poor Contact at Switch.                    }
+  Primary Wires Broken, or Short Circuited.  } Battery and
+  Battery Grounded in Metal Container.       } Coil Ignition
+  Battery Connectors Broken or Loose.        } System Only.
+  Timer Points Out of Adjustment.            }
+  Defects in Induction Coil.                 }
+  Ignition Timing Wrong, Spark Too Late or Too Early.
+  Defective Platinum Points in Breaker Box (Magneto).
+  Points Not Separating.
+  Broken Contact Maker Spring.
+  No Contact at Secondary Collector Brush.
+  Platinum Contact Points Burnt or Pitted.
+  Contact Breaker Bell Crank Stuck.
+  Fiber Bushing in Bell Crank Swollen.
+  Short Circuiting Spring Always in Contact.
+  Dirt or Water in Magneto Casing.
+  Oil in Contact Breaker.
+  Oil Soaked Brush and Collector Ring.
+  Distributor Filled with Carbon Particles.
+
+
+_Motor Stops Without Warning_
+
+  Broken Magneto Carbon Brush.
+  Broken Lead Wire.
+  Broken Ground Wire.
+  Battery Ignition Systems.
+  Water on High Tension Magneto Terminal.
+  Main Secondary Cable Burnt Through by Hot Exhaust
+  Pipe (Transformer Coil, Magneto Systems).
+  Particle of Carbon Between Spark Plug Points.
+  Magneto Short Circuited by Ground Wire.
+  Magneto Out of Time, Due to Slipping Drive.
+  Water or Oil in Safety Spark Gap (Multi-cylinder Magneto).
+  Magneto Contact Breaker or Timer Stuck in Retard
+  Position.
+  Worn Fiber Block in Magneto Contact Breaker.
+  Binding Fiber Bushing in Contact Breaker Bell Crank.
+  Spark Advance Rod or Wire Broken.
+  Contact Breaker Parts Stuck.
+
+
+_Motor Runs Irregularly or Misfires_
+
+  Loose Wiring or Terminals.
+  Broken Spark-Plug Insulator.
+  Spark-Plug Points Sooted or Oily.
+  Wrong Spark Gap at Plug Points.
+  Leaking Secondary Cable.
+  Prematurely Grounded Primary Wire.
+  Batteries Running Down (Battery Ignition only).
+  Poor Adjustment of Contact Points at Timer.
+  Wire Broken Inside of Insulation.
+  Loose Platinum Points in Magneto.
+  Weak Contact Spring.
+  Broken Collector Brush.
+  Dirt in Magneto Distributor Casing or Contact Breaker.
+  Worn Fiber Block or Cam Plate in Magneto.
+  Worn Cam or Contact Roll in Timer (Battery System
+  only).
+  Dirty Oil in Timer.
+  Sticking Coil Vibrators.
+  Coil Vibrator Points Pitted.
+  Oil Soaked Magneto Winding.
+  Punctured Magneto or Coil Winding.
+  Distributor Contact Segments Rough.
+  Sulphated Storage Battery Terminals.
+  Weak Magnets in Magneto.
+  Poor Contact at Magneto Contact Breaker Points.
+
+
+DEFECTS IN ELECTRICAL SYSTEM COMPONENTS
+
+To further simplify the location of electrical system faults it is
+thought desirable to outline the defects that can be present in the
+various parts of the individual devices comprising the ignition system.
+If an airplane engine is provided with magneto ignition solely, as most
+engines are at the present time, no attention need be paid to such items
+as storage or dry batteries, timer or induction coil. There seems to be
+some development in the direction of battery ignition so it has been
+considered desirable to include components of these systems as well as
+the almost universally used magneto group. Spark-plugs, wiring and
+switches are needed with either system.
+
+
+SPARK-PLUGS
+
+  DEFECT                       TROUBLE CAUSED          REMEDY
+  Insulation cracked.          Plug inoperative.       New insulation.
+  Insulation oil soaked.       Cylinder misfires.      Clean.
+  Carbon deposits.             Short circuited spark.  Remove.
+  Insulator loose.             Cylinder misfires.      Tighten.
+  Gasket broken.               Gas leaks by.           New gasket.
+  Electrode loose on shell.    Cylinder misfires.      Tighten.
+  Wire loose in insulator.     Cylinder misfires.      Tighten.
+  Air gap too close.           Short circuits spark.   Set correctly.
+  Air gap too wide.            Spark will not jump.    Set points 1/32"
+                                                       apart.
+  Loose terminal.              Cylinder may misfire.   Tighten.
+  Plug loose in cylinder.      Gas leaks.              Tighten.
+  Mica insulation oil soaked.  Short circuits spark.   Replace.
+
+
+MAGNETO
+
+  DEFECT                       TROUBLE CAUSED          REMEDY
+  Dirty oil in distributor.    Engine misfires.        Clean.
+  Metal dust in distributor.   Engine misfires.        Clean.
+  Brushes not making contact.  Current cannot pass.    Strengthen
+                                                       spring.
+  Distributor segments worn.   Engine misfires.        Secure even
+                                                       bearing.
+  Collecting brush broken.     Engine misfires.        New brush.
+  Distributing brush broken.   Engine misfires.        New brush.
+  Oil soaked winding.          Engine misfires.        Clean.
+  Magnets loose on pole        Engine misfires.        Tighten screws.
+  pieces.
+  Armature rubs.               Engine misfires.        Repair bearings.
+  Bearings worn.               Noisy.                  Replace.
+  Magnets weak.                Weak spark.             Recharge.
+  Contact breaker points       Engine misfires.        Clean.
+  pitted.
+  Breaker points out of        Engine misfires.        Reset.
+  adjustment.
+  Defective winding (rare).    No spark.               Replace.
+  Punctured condenser (rare).  Weak or no spark.       Replace.
+  Driving gear loose.          Noise.                  Tighten.
+  Magneto armature out of      Spark will not fire     Retime.
+  time.                        charge.
+  Magneto loose on base.       Misfiring and noisy.    Tighten.
+  Contact breaker cam worn.    Misfiring.              Replace.
+  Fibre shoe or rolls worn     Misfiring.              Replace.
+  (Bosch).
+  Fibre bushing binding in     Misfiring.              Ream slightly.
+  contact lever (Bosch).
+  Contact lever return spring  No spark.               Replace.
+  broken.
+  Contact lever return spring  Misfiring.              Replace.
+  weak.
+  Ground wire grounded.        No spark.               Insulate.
+  Ground wire broken.          Engine will not stop.   Connect up.
+  Safety spark gap dirty.      No spark.               Clean.
+  Fused metal in spark gap.    No spark.               Remove.
+  Safety spark gap points too  Misfiring.              Set properly.
+  close.
+  Loose distributor terminals. Misfiring.              Tighten.
+  Contact breaker sticks.      No spark control.       Remove and clean
+                                                       bearings.
+  Magneto switch short-        No spark.               Insulate.
+  circuited.
+  Magneto switch open circuit. No engine stop.         Restore contact.
+
+
+STORAGE BATTERY
+
+  DEFECT                       TROUBLE CAUSED          REMEDY
+  Electrolyte low.             Weak current.           Replenish with
+                                                       distilled water.
+  Loose terminals.             Misfiring.              Tighten.
+  Sulphated terminals.         Misfiring.              Clean thoroughly
+                                                       and coat with
+                                                       vaseline.
+  Battery discharged.          Misfiring or no spark.  New charge.
+  Electrolyte weak.            Weak current.           Bring to proper
+                                                       specific gravity.
+  Plates sulphated.            Poor capacity.          Special slow charge.
+  Sediment or mud in bottom.   Weak current.           Clean out.
+  Active material loose in     Poor capacity.          New plates.
+  grids.
+  Moisture or acid on top of   Shorts terminals.       Remove.
+  cells.
+  Plugged vent cap.            Buckles cell jars.      Make vent hole.
+  Cracked vent cap.            Acid spills out.        New cap.
+  Cracked cell jar.            Electrolyte runs out.   New jar.
+
+DRY CELL BATTERY
+
+  DEFECT                       TROUBLE CAUSED          REMEDY
+  Broken wires.                No current.             New wires.
+  Loose terminals.             Misfiring.              Tighten.
+  Weak cell (7 amperes or      Misfiring.              New cells.
+  less).
+  Cells in contact.            Short circuit.          Separate and
+                                                       insulate.
+  Water in battery box.        Short circuit.          Dry out.
+
+
+TIMER
+
+  DEFECT                       TROUBLE CAUSED          REMEDY
+  Contact segments worn or     Misfiring.              Grind down
+  pitted.                                              smooth.
+  Platinum points pitted.      Misfiring.              Smooth with oil
+                                                       stone.
+  Dirty oil or metal dust in   Misfiring.              Clean out.
+  interior.
+  Worn bearing.                Misfiring.              Replace.
+  Loose terminals.             Misfiring.              Tighten.
+  Worn revolving contact       Misfiring.              Replace.
+  brush.
+  Out of time.                 Irregular spark.        Reset.
+
+
+INDUCTION COIL
+
+  DEFECT                       TROUBLE CAUSED          REMEDY
+  Loose terminals.             Misfiring.              Tighten.
+  Broken connections.          No spark.               Make new joints.
+  Vibrators out of adjustment. Misfiring.              Readjust.
+  Vibrator points pitted.      Misfiring.              Clean.
+  Defective condenser } rare.  No spark.               Send to maker
+  Defective winding   }                                for repairs.
+  Poor contact at switch.      Misfiring.              Tighten.
+  Broken internal wiring.      No spark.               Replace.
+  Poor coil unit.              One cylinder affected.  Replace.
+
+
+WIRING
+
+  DEFECT                       TROUBLE CAUSED          REMEDY
+  Loose terminals anywhere.    Misfiring.              Tighten.
+  Broken plug wire.            One cylinder will not   Replace.
+                               fire.
+  Broken timer wire.           One coil will not buzz. Replace.
+  Broken main battery wire.  } No spark.               Replace.
+  Broken battery ground wire.}
+  Broken magneto ground wire.  Engine will not stop.   Replace.
+  Chafed insulation anywhere.} Misfiring.              Insulate.
+  Short circuit anywhere.    }
+
+
+CARBURETION SYSTEM FAULTS SUMMARIZED
+
+
+_Motor Starts Hard or Will Not Start_
+
+  No Gasoline in Tank.
+  No Gasoline in Carburetor Float Chamber.
+  Tank Shut-Off Closed.
+  Clogged Filter Screen.
+  Fuel Supply Pipe Clogged.
+  Gasoline Level Too Low.
+  Gasoline Level Too High (Flooding).
+  Bent or Stuck Float Lever.
+  Loose or Defective Inlet Manifold.
+  Not Enough Gasoline at Jet.
+  Cylinders Flooded with Gas.
+  Fuel Soaked Cork Float (Causes Flooding).
+  Water in Carburetor Spray Nozzle.
+  Dirt in Float Chamber.
+  Gas Mixture Too Lean.
+  Carburetor Frozen (Winter Only).
+
+
+_Motor Stops In Flight_
+
+  Gasoline Shut-Off Valve Jarred Closed.
+  Gasoline Supply Pipe Clogged.
+  No Gasoline in Tank.
+  Spray Nozzle Stopped Up.
+  Water in Spray Nozzle.
+  Particles of Carbon Between Spark-Plug Points.
+  Magneto Short Circuited by Ground in Wire.
+  Air Lock in Gasoline Pipe.
+  Broken Air Line or Leaky Tank (Pressure Feed System Only).
+  Fuel Supply Pipe Partially Clogged.
+  Air Vent in Tank Filler Cap Stopped Up (Gravity and Vacuum Feed
+  System).
+  Float Needle Valve Stuck.
+  Water or Dirt in Spray Nozzle.
+  Mixture Adjusting Needle Jarred Loose (Rotary Motors Only).
+
+
+_Motor Races, Will Not Throttle Down_
+
+  Air Leak in Inlet Piping.
+  Air Leak Through Inlet Valve Guides.
+  Control Rods Broken.
+  Defective Induction Pipe Joints.
+  Leaky Carburetor Flange Packing.
+  Throttle Not Closing.
+  Poor Slow Speed Adjustment (Zenith Carburetor).
+
+
+_Motor Misfires_
+
+  Carburetor Float Chamber Getting Dry.
+  Water or Dirt in Gasoline.
+  Poor Gasoline Adjustment (Rotary Motors).
+  Not Enough Gasoline in Float Chamber.
+  Too Much Gasoline, Carburetor Flooding.
+  Incorrect Jet or Choke (Zenith Carburetor).
+  Broken Cylinder Head Packing Between Cylinders.
+
+
+_Noisy Operation_
+
+  Popping or Blowing Back in Carburetor.
+  Incorrectly Timed Inlet Valves.
+  Inlet Valve Not Seating.
+  Defective Inlet Valve Spring.
+  Dirt Under Inlet Valve Seat.
+  Not Enough Gasoline (Open Needle Valve).
+  Muffler or Manifold Explosions.
+  Mixture Not Exploding Regularly.
+  Exhaust Valve Sticking.
+  Dirt Under Exhaust Valve Seat.
+
+
+
+
+CHAPTER XI
+
+    Tools for Adjusting and Erecting--Forms of Wrenches--Use and
+    Care of Files--Split Pin Removal and Installation--Complete
+    Chisel Set--Drilling Machines--Drills, Reamers, Taps and Dies--
+    Measuring Tools--Micrometer Calipers and Their Use--Typical Tool
+    Outfits--Special Hall-Scott Tools--Overhauling Airplane Engines
+    --Taking Engine Down--Defects in Cylinders--Carbon Deposits,
+    Cause and Prevention--Use of Carbon Scrapers--Burning Out Carbon
+    with Oxygen--Repairing Scored Cylinders--Valve Removal and
+    Inspection--Reseating and Truing Valves--Valve Grinding
+    Processes--Depreciation in Valve Operating System--Piston
+    Troubles--Piston Ring Manipulation--Fitting Piston Rings--
+    Wrist-Pin Wear--Inspection and Refitting of Engine Bearings--
+    Scraping Brasses to Fit--Fitting Connecting Rods--Testing for
+    Bearing Parallelism--Cam-Shafts and Timing Gears--Precautions in
+    Reassembling Parts.
+
+
+TOOLS FOR ADJUSTING AND ERECTING
+
+[Illustration: Fig. 163.--Practical Hand Tools Useful in Dismantling and
+Repairing Airplane Engines.]
+
+A very complete outfit of small tools, some of which are furnished as
+part of the tool equipment of various engines are shown in group at Fig.
+163. This group includes all of the tools necessary to complete a very
+practical kit and it is not unusual for the mechanic who is continually
+dismantling and erecting engines to possess even a larger assortment
+than indicated. The small bench vise provided is a useful auxiliary that
+can be clamped to any convenient bench or table or even fuselage
+longeron in an emergency and should have jaws at least three inches wide
+and capable of opening four or five inches. It is especially useful in
+that it will save trips to the bench vises, as it has adequate capacity
+to handle practically any of the small parts that need to be worked on
+when making repairs. A blow torch, tinner's snips and soldering copper
+are very useful in sheet metal work and in making any repairs requiring
+the use of solder. The torch can be used in any operation requiring a
+source of heat. The large box wrench shown under the vise is used for
+removing large special nuts and sometimes has one end of the proper size
+to fit the valve chamber cap. The piston ring removers are easily made
+from thin strips of sheet metal securely brazed or soldered to a light
+wire handle. These are used in sets of three for removing and applying
+piston rings in a manner to be indicated. The uses of the wrenches,
+screw drivers, and pliers shown are known to all and the variety
+outlined should be sufficient for all ordinary work of restoration. The
+wrench equipment is very complete, including a set of open end
+S-wrenches to fit all standard bolts, a spanner wrench, socket or box
+wrenches for bolts that are inaccessible with the ordinary type,
+adjustable end wrenches, a thin monkey wrench of medium size, a bicycle
+wrench for handling small nuts and bolts, a Stillson wrench for pipe and
+a large adjustable monkey wrench for the stubborn fastenings of large
+size.
+
+Four different types of pliers are shown, one being a parallel jaw type
+with size cutting attachment, while the other illustrated near it is a
+combination parallel jaw type adapted for use on round work as well as
+in handling flat stock. The most popular form of pliers is the
+combination pattern shown beneath the socket wrench set. This is made of
+substantial drop forgings having a hinged joint that can be set so that
+a very wide opening at the jaws is possible. These can be used on round
+work and for wire cutting as well as for handling flat work. Round nose
+pliers are very useful also.
+
+A very complete set of files, including square, half round, mill, flat
+bastard, three-cornered and rat tail are also necessary. A hacksaw frame
+and a number of saws, some with fine teeth for tubing and others with
+coarser teeth for bar or solid stock will be found almost indispensable.
+A complete punch and chisel set should be provided, samples of which are
+shown in the group while the complete outfit is outlined in another
+illustration. A number of different forms and sizes of chisels are
+necessary, as one type is not suitable for all classes of work. The
+adjustable end wrenches can be used in many places where a monkey wrench
+cannot be fitted and where it will be difficult to use a wrench having a
+fixed opening. The Stillson pipe wrench is useful in turning studs,
+round rods, and pipes that cannot be turned by any other means. A
+complete shop kit must necessarily include various sizes for Stillson
+and monkey wrenches, as no one size can be expected to handle the wide
+range of work the engine repairman must cope with. Three sizes of each
+form of wrench can be used, one, a 6 inch, is as small as is needed
+while, a 12 inch tool will handle almost any piece of pipe or nut used
+in engine construction.
+
+Three or four sizes of hammers should be provided, according to
+individual requirement, these being small riveting, medium and
+heavyweight machinist's hammers. A very practical tool of this nature
+for the repair shop can be used as a hammer, screw driver or pry iron.
+It is known as the "Spartan" hammer and is a tool steel drop forging in
+one piece having the working surfaces properly hardened and tempered
+while the metal is distributed so as to give a good balance to the head
+and a comfortable grip to the handle. The hammer head provides a
+positive and comfortable T-handle when the tool is used as a screw
+driver or "tommy" bar. Machinist's hammers are provided with three types
+of heads, these being of various weights. The form most commonly used is
+termed the "ball pein" on account of the shape of the portion used for
+riveting. The straight pein is just the same as the cross pein, except
+that in the latter the straight portion is at right angles to the hammer
+handle, while in the former it is parallel to that member.
+
+
+FORMS OF WRENCHES
+
+Wrenches have been made in infinite variety and there are a score or
+more patterns of different types of adjustable socket and off-set
+wrenches. The various wrench types that differ from the more
+conventional monkey wrenches or those of the Stillson pattern are shown
+at Fig. 164. The "perfect handle" is a drop forged open end form
+provided with a wooden handle similar to that used on a monkey wrench in
+order to provide a better grip for the hand. The "Saxon" wrench is a
+double alligator form, so called because the jaws are in the form of a
+V-groove having one side of the V plain, while the other is serrated in
+order to secure a tight grip on round objects. In the form shown, two
+jaws of varying sizes are provided, one for large work, the other to
+handle the smaller rods. One of the novel features in connection with
+this wrench is the provision of a triple die block in the centre of the
+handle which is provided with three most commonly used of the standard
+threads including 5/16-inch-18, 3/8-inch-16, and 1/2-inch-13. This is
+useful in cleaning up burred threads on bolts before they are replaced,
+as burring is unavoidable if it has been necessary to drive them out
+with a hammer. The "Lakeside" wrench has an adjustable pawl engaging
+with one of a series of notches by which the opening may be held in any
+desired position.
+
+[Illustration: Fig. 164.--Wrenches are Offered in Many Forms.]
+
+Ever since the socket wrench was invented it has been a popular form
+because it can be used in many places where the ordinary open end or
+monkey wrench cannot be applied owing to lack of room for the head of
+the wrench. A typical set which has been made to fit in a very small
+space is shown at D. It consists of a handle, which is nickel-plated and
+highly polished, a long extension bar, a universal joint and a number of
+case hardened cold drawn steel sockets to fit all commonly used standard
+nuts and bolt heads. Two screw-driver bits, one small and the other
+large to fit the handle, and a long socket to fit spark-plugs are also
+included in this outfit. The universal joint permits one to remove nuts
+in a position that would be inaccessible to any other form of wrench, as
+it enables the socket to be turned even if the handle is at one side of
+an intervening obstruction.
+
+The "Pick-up" wrench, shown at E, is used for spark-plugs and the upper
+end of the socket is provided with a series of grooves into which a
+suitable blade carried by the handle can be dropped. The handle is
+pivoted to the top of the socket in such a way that the blades may be
+picked up out of the grooves by lifting on the end of the handle and
+dropped in again when the handle is swung around to the proper point to
+get another hold on the socket. The "Miller" wrench shown at F, is a
+combination socket and open end type, made especially for use with
+spark-plugs. Both the open end and the socket are convenient. The
+"Handy" set shown at G, consists of a number of thin stamped wrenches of
+steel held together in a group by a simple clamp fitting, which enables
+either end of any one of the four double wrenches to be brought into
+play according to the size of the nut to be turned. The "Cronk" wrench
+shown at H, is a simple stamping having an alligator opening at one end
+and a stepped opening capable of handling four different sizes of
+standard nuts or bolt heads at the other. Such wrenches are very cheap
+and are worth many times their small cost, especially for fitting nuts
+where there is not sufficient room to admit the more conventional
+pattern. The "Starrett" wrench set, which is shown at I, consists of a
+ratchet handle together with an extension bar and universal joint, a
+spark-plug socket, a drilling attachment which takes standard square
+shank drills from 1/8-inch to 1/2-inch in diameter, a double ended
+screw-driver bit and several adjustments to go with the drilling
+attachment. Twenty-eight assorted cold drawn steel sockets similar in
+design to those shown at D, to fit all standard sizes of square and
+hexagonal headed nuts are also included. The reversible ratchet handle,
+which may be slipped over the extension bar or the universal joint and
+which is also adapted to take the squared end of any one of the sockets
+is exceptionally useful in permitting, as it does, the instant release
+of pressure when it is desired to swing the handle back to get another
+hold on the nut. The socket wrench sets are usually supplied in hard
+wood cases or in leather bags so that they may be kept together and
+protected against loss or damage. With a properly selected socket wrench
+set, either of the ratchet handle or T-handle form, any nut on the
+engine may be reached and end wrenches will not be necessary.
+
+
+USE AND CARE OF FILES
+
+Mention has been previously made of the importance of providing a
+complete set of files and suitable handles. These should be in various
+grades or degrees of fineness and three of each kind should be provided.
+In the flat and half round files three grades are necessary, one with
+coarse teeth for roughing, and others with medium and fine teeth for the
+finishing cuts. The round or rat tail file is necessary in filing out
+small holes, the half round for finishing the interior of large ones.
+Half round files are also well adapted for finishing surfaces of
+peculiar contour, such as the inside of bearing boxes, connecting rod
+and main bearing caps, etc. Square files are useful in finishing keyways
+or cleaning out burred splines, while the triangular section or
+three-cornered file is of value in cleaning out burred threads and
+sharp corners. Flat files are used on all plane surfaces.
+
+[Illustration: Fig. 165.--Illustrating Use and Care of Files.]
+
+The file brush shown at Fig. 165, A, consists of a large number of wire
+bristles attached to a substantial wood back having a handle of
+convenient form so that the bristles may be drawn through the
+interstices between the teeth of the file to remove dirt and grease. If
+the teeth are filled with pieces of soft metal, such as solder or
+babbitt, it may be necessary to remove this accumulation with a piece of
+sheet metal as indicated at Fig. 165, B. The method of holding a file
+for working on plain surfaces when it is fitted with the regular form of
+wooden handle is shown at C, while two types of handles enabling the
+mechanic to use the flat file on plain surfaces of such size that the
+handle type indicated at C, could not be used on account of interfering
+with the surface finished are shown at D. The method of using a file
+when surfaces are finished by draw filing is shown at E. This differs
+from the usual method of filing and is only used when surfaces are to be
+polished and very little metal removed.
+
+
+SPLIT PIN REMOVAL AND INSERTION
+
+One of the most widely used of the locking means to prevent nuts or
+bolts from becoming loose is the simple split pin, sometimes called a
+"cotter pin." These can be handled very easily if the special pliers
+shown at Fig. 166, A, are used. They have a curved jaw that permits of
+grasping the pin firmly and inserting it in the hole ready to receive
+it. It is not easy to insert these split pins by other means because the
+ends are usually spread out and it is hard to enter the pin in the hole.
+With the cotter pin pliers the ends may be brought close together and as
+the plier jaws are small the pin may be easily pushed in place. Another
+use of this plier, also indicated, is to bend over the ends of the split
+pin in order to prevent it from falling out. To remove these pins a
+simple curved lever, as shown at Fig. 166, B, is used. This has one end
+tapering to a point and is intended to be inserted in the eye of the
+cotter pin, the purchase offered by the handle permitting of ready
+removal of the pin after the ends have been closed by the cotter pin
+pliers.
+
+
+COMPLETE CHISEL SET
+
+[Illustration: Fig. 166.--Outlining Use of Cotter Pin Pliers, Spring
+Winder, and Showing Practical Outfit of Chisels.]
+
+A complete chisel set suitable for repair shop use is also shown at Fig.
+166. The type at C is known as a "cape" chisel and has a narrow cutting
+point and is intended to chip keyways, remove metal out of corners and
+for all other work where the broad cutting edge chisel, shown at D,
+cannot be used. The form with the wide cutting edge is used in chipping,
+cutting sheet metal, etc. At E, a round nose chisel used in making oil
+ways is outlined, while a similar tool having a pointed cutting edge and
+often used for the same purpose is shown at F. The centre punch depicted
+at G, is very useful for marking parts either for identification or for
+drilling. In addition to the chisels shown, a number of solid punches
+or drifts resembling very much that shown at E, except that the point is
+blunt should be provided to drive out taper pins, bolts, rivets, and
+other fastenings of this nature. These should be provided in the common
+sizes. A complete set of real value would start at 1/8-inch and increase
+by increments of 1/32-inch up to 1/2-inch. A simple spring winder is
+shown at Fig. 166, H, this making it possible for the repairman to wind
+coil springs, either on the lathe or in the vise. It will handle a
+number of different sizes of wire and can be set to space the coils as
+desired.
+
+
+DRILLING MACHINES
+
+[Illustration: Fig. 167.--Forms of Hand Operated Drilling Machines.]
+
+Drilling machines may be of two kinds, hand or power operated. For
+drilling small holes in metal it is necessary to run the drill fast,
+therefore the drill chuck is usually driven by gearing in order to
+produce high drill speed without turning the handle too fast. A small
+hand drill is shown at Fig. 167, A. As will be observed, the chuck
+spindle is driven by a small bevel pinion, which in turn, is operated by
+a large bevel gear turned by a crank. The gear ratio is such that one
+turn of the handle will turn the chuck five or six revolutions. A drill
+of this design is not suited for drills any larger than one-quarter
+inch. For use with drills ranging from one-eighth to three-eighths, or
+even half-inch the hand drill presses shown at C and D are used. These
+have a pad at the upper end by which pressure may be exerted with the
+chest in order to feed the drill into the work, and for this reason they
+are termed "breast drills." The form at C has compound gearing, the
+drill chuck being driven by the usual form of bevel pinion in mesh with
+a larger bevel gear at one end of a countershaft. A small helical spur
+pinion at the other end of this countershaft receives its motion from a
+larger gear turned by the hand crank. This arrangement of gearing
+permits of high spindle speed without the use of large gears, as would
+be necessary if but two were used. The form at D gives two speeds, one
+for use with small drills is obtained by engaging the lower bevel pinion
+with the chuck spindle and driving it by the large ring gear. The slow
+speed is obtained by shifting the clutch so that the top bevel pinion
+drives the drill chuck. As this meshes with a gear but slightly larger
+in diameter, a slow speed of the drill chuck is possible. Breast drills
+are provided with a handle screwed into the side of the frame, these
+are used to steady the drill press. For drilling extremely large holes
+which are beyond the capacity of the usual form of drill press the
+ratchet form shown at B, may be used or the bit brace outlined at E. The
+drills used with either of these have square shanks, whereas those used
+in the drill presses have round shanks. The bit brace is also used
+widely in wood work and the form shown is provided with a ratchet by
+which the bit chuck may be turned through only a portion of a revolution
+in either direction if desired.
+
+
+DRILLS, REAMERS, TAPS AND DIES
+
+In addition to the larger machine tools and the simple hand tools
+previously described, an essential item of equipment of any engine or
+plane repair shop, even in cases where the ordinary machine tools are
+not provided, is a complete outfit of drills, reamers, and threading
+tools. Drills are of two general classes, the flat and the twist drills.
+The flat drill has an angle between cutting edges of about 110 degrees
+and is usually made from special steel commercially known as drill rod.
+
+A flat drill cannot be fed into the work very fast because it removes
+metal by a scraping, rather than a cutting process. The twist drill in
+its simplest form is cylindrical throughout the entire length and has
+spiral flutes which are ground off at the end to form the cutting lip
+and which also serve to carry the metal chips out of the holes. The
+simplest form of twist drill used is shown at Fig. 168, C, and is known
+as a "chuck" drill, because it must be placed in a suitable chuck to
+turn it. A twist drill removes metal by cutting and it is not necessary
+to use a heavy feed as the drill will tend to feed itself into the work.
+
+[Illustration: Fig. 168.--Forms of Drills Used in Hand and Power
+Drilling Machines.]
+
+Larger drills than 3/4-inch are usually made with a tapered shank as
+shown at Fig. 168, B. At the end of the taper a tongue is formed which
+engages with a suitable opening in the collet, as the piece used to
+support the drill is called. The object of this tongue is to relieve
+the tapered portion of the drill from the stress of driving by
+frictional contact alone, as this would not turn the drill positively
+and the resulting slippage would wear the socket, this depreciation
+changing the taper and making it unfit for other drills. The tongue is
+usually proportioned so it is adequate to drive the drill under any
+condition. A small keyway is provided in the collet into which a
+tapering key of flat stock may be driven against the end of the tongue
+to drive the drill from the spindle. A standard taper for drill shanks
+generally accepted by the machine trade is known as the Morse and is a
+taper of five-eighths of an inch to the foot. The Brown and Sharp form
+tapers six-tenths of an inch to the foot. Care must be taken, therefore,
+when purchasing drills and collets, to make sure that the tapers
+coincide, as no attempt should be made to run a Morse taper in a Brown
+and Sharp collet, or vice versa.
+
+Sometimes cylindrical drills have straight flutes, as outlined at Fig.
+168, A. Such drills are used with soft metals and are of value when the
+drill is to pass entirely through the work. The trouble with a drill
+with spiral flutes is that it will tend to draw itself through as the
+cutting lips break through. This catching of the drill may break it or
+move the work from its position. With a straight flute drill the cutting
+action is practically the same as with the flat drill shown at Fig. 168,
+E and F.
+
+If a drill is employed in boring holes through close-grained, tough
+metals, as wrought or malleable iron and steel, the operation will be
+facilitated by lubricating the drill with plenty of lard oil or a
+solution of soda and water. Either of these materials will effectually
+remove the heat caused by the friction of the metal removed against the
+lips of the drill, and the danger of heating the drill to a temperature
+that will soften it by drawing the temper is minimized. In drilling
+large or deep holes it is good practice to apply the lubricating medium
+directly at the drill point. Special drills of the form shown at Fig.
+168, B, having a spiral oil tube running in a suitably formed channel,
+provides communication between the point of the drill and a suitable
+receiving hole on a drilled shank. The oil is supplied by a pump and its
+pressure not only promotes positive circulation and removal of heat, but
+also assists in keeping the hole free of chips. In drilling steel or
+wrought iron, lard oil applied to the point of the drill will facilitate
+the drilling, but this material should never be used with either brass
+or cast iron.
+
+The sizes to be provided depend upon the nature of the work and the
+amount of money that can be invested in drills. It is common practice to
+provide a set of drills, such as shown at Fig. 169, which are carried in
+a suitable metal stand, these being known as number drills on account
+of conforming to the wire gauge standards. Number drills do not usually
+run higher than 5/16 inch in diameter. Beyond this point drills are
+usually sold by the diameter. A set of chuck drills, ranging from 3/8 to
+3/4 inch, advancing by 1/32 inch, and a set of Morse taper shank drills
+ranging from 3/4 to 1-1/4 inches, by increments of 1/16 inch, will be
+all that is needed for the most pretentious repair shop, as it is
+cheaper to bore holes larger than 1-1/4 inches with a boring tool than
+it is to carry a number of large drills in stock that would be used very
+seldom, perhaps not enough to justify their cost.
+
+[Illustration: Fig. 169.--Useful Set of Number Drills, Showing Stand for
+Keeping These in an Orderly Manner.]
+
+In grinding drills, care must be taken to have the lips of the same
+length, so that they will form the same angle with the axis. If one lip
+is longer than the other, as shown in the flat drill at Fig. 168, E, the
+hole will be larger than the drill size, and all the work of cutting
+will come upon the longest lip. The drill ends should be symmetrical, as
+shown at Fig. 168, F.
+
+[Illustration: Fig. 170.--Illustrating Standard Forms of Hand and
+Machine Reamers.]
+
+It is considered very difficult to drill a hole to an exact diameter,
+but for the most work a variation of a few thousandths of an inch is of
+no great moment. Where accuracy is necessary, holes must be reamed out
+to the required size. In reaming, a hole is drilled about 1/32 inch
+smaller than is required, and is enlarged with a cutting tool known as
+the reamer. Reamers are usually of the fluted form shown at Fig. 170, A.
+Tools of this nature are not designed to remove considerable amounts of
+metal, but are intended to augment the diameter of the drill hole by
+only a small fraction of an inch. Reamers are tapered slightly at the
+point in order that they will enter the hole easily, but the greater
+portion of the fluted part is straight, all cutting edges being
+parallel. Hand reamers are made in either the straight or taper forms,
+that at A, Fig. 170, being straight, while B has tapering flutes. They
+are intended to be turned by a wrench similar to that employed in
+turning a tap, as shown at Fig. 172, C. The reamer shown at Fig. 170,
+C, is a hand reamer. The form at D has spiral flutes similar to a twist
+drill, and as it is provided with a taper shank it is intended to be
+turned by power through the medium of a suitable collet.
+
+As the solid reamers must become reduced in size when sharpened, various
+forms of inserted blade reamers have been designed. One of these is
+shown at E, and as the cutting surfaces become reduced in diameter it is
+possible to replace the worn blades with others of proper size.
+Expanding reamers are of the form shown at F. These have a bolt passing
+through that fits into a tapering hole in the interior of the split
+reamer portion of the tool. If the hole is to be enlarged a few
+thousandths of an inch, it is possible to draw up on the nut just above
+the squared end of the shank, and by drawing the tapering wedge farther
+into the reamer body, the cutting portion will be expanded and will cut
+a larger hole.
+
+Reamers must be very carefully sharpened or there will be a tendency
+toward chattering with a consequent production of a rough surface. There
+are several methods of preventing this chattering, one being to separate
+the cutting edges by irregular spaces, while the most common method, and
+that to be preferred on machine reamers, is to use spiral flutes, as
+shown at Fig. 170, D. Special taper reamers are made to conform to the
+various taper pin sizes which are sometimes used in holding parts
+together in an engine. A taper of 1/16 inch per foot is intended for
+holes where a pin, once driven in, is to remain in place. When it is
+desired that the pin be driven out, the taper is made steeper, generally
+1/4 inch per foot, which is the standard taper used on taper pins.
+
+[Illustration: Fig. 171.--Tools for Thread Cutting.]
+
+When threads are to be cut in a small hole, it will be apparent that it
+will be difficult to perform this operation economically on a lathe,
+therefore when internal threading is called for, a simple device known
+as a "tap" is used. There are many styles of taps, all conforming to
+different standards. Some are for metric or foreign threads, some
+conform to the American standards, while others are used for pipe and
+tubing. Hand taps are the form most used in repair shops, these being
+outlined at Fig. 171, A and B. They are usually sold in sets of three,
+known respectively as taper, plug, and bottoming. The taper tap is the
+one first put into the hole, and is then followed by the plug tap which
+cuts the threads deeper. If it is imperative that the thread should be
+full size clear to the bottom of the hole, the third tap of the set,
+which is straight-sided, is used. It would be difficult to start a
+bottoming tap into a hole because it would be larger in diameter at its
+point than the hole. The taper tap, as shown at A, Fig. 171, has a
+portion of the cutting lands ground away at the point in order that it
+will enter the hole. The manipulation of a tap is not hard, as it does
+not need to be forced into the work, as the thread will draw it into
+the hole as the tap is turned. The tapering of a tap is done so that no
+one thread is called upon to remove all of the metal, as for about half
+way up the length of the tap each succeeding thread is cut a little
+larger by the cutting edge until the full thread enters the hole. Care
+must be taken to always enter a tap straight in order to have the thread
+at correct angles to the surface.
+
+In cutting external threads on small rods or on small pieces, such as
+bolts and studs, it is not always economical to do this work in the
+lathe, especially in repair work. Dies are used to cut threads on pieces
+that are to be placed in tapped holes that have been threaded by the
+corresponding size of tap. Dies for small work are often made solid, as
+shown at Fig. 171, C, but solid dies are usually limited to sizes below
+1/2 inch. Sometimes the solid die is cylindrical in shape, with a slot
+through one side which enables one to obtain a slight degree of
+adjustment by squeezing the slotted portion together. Large dies, or the
+sizes over 1/2 inch, are usually made in two pieces in order that the
+halves may be closed up or brought nearer together. The advantage of
+this form of die is that either of the two pieces may be easily
+sharpened, and as it may be adjusted very easily the thread may be cut
+by easy stages. For example, the die may be adjusted to cut large, which
+will produce a shallow thread that will act as an accurate guide when
+the die is closed up and a deeper thread cut.
+
+[Illustration: Fig. 172.--Showing Holder Designs for One- and Two-Piece
+Thread Cutting Dies.]
+
+A common form of die holder for an adjustable die is shown at Fig. 172,
+A. As will be apparent, it consists of a central body portion having
+guide members to keep the die pieces from falling out and levers at each
+end in order to permit the operator to exert sufficient force to remove
+the metal. The method of adjusting the depth of thread with a clamp
+screw when a two-piece die is employed is also clearly outlined. The
+diestock shown at B is used for the smaller dies of the one-piece
+pattern, having a slot in order that they may be closed up slightly by
+the clamp screw. The reverse side of the diestock shown at B is outlined
+below it, and the guide pieces, which may be easily moved in or out,
+according to the size of the piece to be threaded by means of
+eccentrically disposed semi-circular slots in the adjustment plate, are
+shown. These movable guide members have small pins let into their
+surface which engage the slots, and they may be moved in or out, as
+desired, according to the position of the adjusting plate. The use of
+the guide pieces makes for accurate positioning or centering of the rod
+to be threaded. Dies are usually sold in sets, and are commonly
+furnished as a portion of a complete outfit such as outlined at Fig.
+173. That shown has two sizes of diestock, a tap wrench, eight assorted
+dies, eight assorted taps, and a small screw driver for adjusting the
+die. An automobile repair shop should be provided with three different
+sets of taps and dies, as three different standards for the bolts and
+nuts are used in fastening automobile components. These are the
+American, metric (used on foreign engines), and the S. A. E. standard
+threads. A set of pipe dies and taps will also be found useful.
+
+[Illustration: Fig. 173.--Useful Outfit of Taps and Dies for the Engine
+Repair Shop.]
+
+
+MEASURING TOOLS
+
+The tool outfit of the machinist or the mechanic who aspires to do
+machine work must include a number of measuring tools which are not
+needed by the floor man or one who merely assembles and takes apart the
+finished pieces. The machinist who must convert raw material into
+finished products requires a number of measuring tools, some of which
+are used for taking only approximate measurements, such as calipers and
+scales, while others are intended to take very accurate measurements,
+such as the Vernier and the micrometer. A number of common forms of
+calipers are shown at Fig. 174. These are known as inside or outside
+calipers, depending upon the measurements they are intended to take.
+That at A is an inside caliper, consisting of two legs, A and D, and a
+gauging piece, B, which can be locked to leg A, or released from that
+member by the screw, C. The object of this construction is to permit of
+measurements being taken at the bottom of a two diameter hole, where the
+point to be measured is of larger diameter than the portion of the hole
+through which the calipers entered. It will be apparent that the legs A
+and D must be brought close together to pass through the smaller holes.
+This may be done without losing the setting, as the guide bar B will
+remain in one position as determined by the size of the hole to be
+measured, while the leg A may be swung in to clear the obstruction as
+the calipers are lifted out. When it is desired to ascertain the
+measurements the leg A is pushed back into place into the slotted
+portion of the guide B, and locked by the clamp screw C. A tool of this
+form is known as an internal transfer caliper.
+
+[Illustration: Fig. 174.--Common Forms of Inside and Outside Calipers.]
+
+The form of caliper shown at B is an outside caliper. Those at C and D
+are special forms for inside and outside work, the former being used,
+if desired, as a divider, while the latter may be employed for measuring
+the walls of tubing. The calipers at E are simple forms, having a
+friction joint to distinguish them from the spring calipers shown at B,
+C and D. In order to permit of ready adjustment of a spring caliper, a
+split nut as shown at G is sometimes used. A solid nut caliper can only
+be adjusted by screwing the nut in or out on the screw, which may be a
+tedious process if the caliper is to be set from one extreme to the
+other several times in succession. With a slip nut as shown at G it is
+possible to slip it from one end of the thread to the other without
+turning it, and of locking it in place at any desired point by simply
+allowing the caliper leg to come in contact with it. The method of
+adjusting a spring caliper is shown at Fig. 174, H.
+
+Among the most common of the machinist's tools are those used for linear
+measurements. The usual forms are shown in group, Fig. 175. The most
+common tool, which is widely known, is the carpenter's folding two-foot
+rule or the yardstick. While these are very convenient for taking
+measurements where great accuracy is not required, the machinist must
+work much more accurately than the carpenter, and the standard steel
+scale which is shown at D, is a popular tool for the machinist. The
+steel scale is in reality a graduated straight edge and forms an
+important part of various measuring tools. These are made of high grade
+steel and vary from 1 to 48 inches in length. They are carefully
+hardened in order to preserve the graduations, and all surfaces and
+edges are accurately ground to insure absolute parallelism. The
+graduations on the high grade scales are produced with a special device
+known as a dividing engine, but on cheaper scales, etching suffices to
+provide a fairly accurate graduation. The steel scales may be very thin
+and flexible, or may be about an eighth of an inch thick on the
+twelve-inch size, which is that commonly used with combination squares,
+protractors and other tools of that nature. The repairman's scale
+should be graduated both with the English system, in which the inches
+are divided into eighths, sixteenths, thirty-secondths and
+sixty-fourths, and also in the metric system, divided into millimeters
+and centimeters. Some machinists use scales graduated in tenths,
+twentieths, fiftieths and hundredths. This is not as good a system of
+graduation as the more conventional one first described.
+
+[Illustration: Fig. 175.--Measuring Appliances for the Machinist and
+Floor Man.]
+
+Some steel scales are provided with a slot or groove cut the entire
+length on one side and about the center of the scales. This permits the
+attachment of various fittings such as the protractor head, which
+enables the machinist to measure angles, or in addition the heads
+convert the scale into a square or a tool permitting the accurate
+bisecting of pieces of circular section. Two scales are sometimes joined
+together to form a right angle, such as shown at Fig. 175, C. This is
+known as a square and is very valuable in ascertaining the truth of
+vertical pieces that are supposed to form a right angle with a base
+piece.
+
+The Vernier is a device for reading finer divisions on a scale than
+those into which the scale is divided. Sixty-fourths of an inch are
+about the finest division that can be read accurately with the naked
+eye. When fine work is necessary a Vernier is employed. This consists
+essentially of two rules so graduated that the true scale has each inch
+divided into ten equal parts, the upper or Vernier portion has ten
+divisions occupying the same space as nine of the divisions of the true
+scale. It is evident, therefore, that one of the divisions of the
+Vernier is equal to nine-tenths of one of those on the true scale. If
+the Vernier scale is moved to the right so that the graduations marked
+"1" shall coincide, it will have moved one-tenth of a division on the
+scale or one-hundredth of an inch. When the graduations numbered 5
+coincide the Vernier will have moved five-hundredths of an inch; when
+the lines marked 0 and 10 coincide, the Vernier will have moved
+nine-hundredths of an inch, and when 10 on the Vernier comes opposite 10
+on the scales, the upper rule will have moved ten-hundredths of an inch,
+or the whole of one division on the scale. By this means the scale,
+though it may be graduated only to tenths of an inch, may be accurately
+set at points with positions expressed in hundredths of an inch. When
+graduated to read in thousandths, the true scale is divided into fifty
+parts and the Vernier into twenty parts. Each division of the Vernier
+is therefore equal to nineteen-twentieths of one of the true scale. If
+the Vernier be moved so the lines of the first division coincide, it
+will have moved one-twentieth of one-fiftieth, or .001 inch. The Vernier
+principle can be readily grasped by studying the section of the Vernier
+scale and true scale shown at Fig. 176, A.
+
+[Illustration: Fig. 176.--At Left, Special Form of Vernier Caliper for
+Measuring Gear Teeth; at Right, Micrometer for Accurate Internal
+Measurements.]
+
+The caliper scale which is shown at Fig. 175, A, permits of taking the
+over-all dimension of any parts that will go between the jaws. This
+scale can be adjusted very accurately by means of a fine thread screw
+attached to a movable jaw and the divisions may be divided by eye into
+two parts if one sixty-fourth is the smallest of the divisions. A line
+is indicated on the movable jaw and coincides with the graduations on
+the scale. As will be apparent, if the line does not coincide exactly
+with one of the graduations it will be at some point between the lines
+and the true measurement may be approximated without trouble.
+
+A group of various other measuring tools of value to the machinist is
+shown at Fig. 177. The small scale at A is termed a "center gauge,"
+because it can be used to test the truth of the taper of either a male
+or female lathe center. The two smaller nicks, or v's, indicate the
+shape of a standard thread, and may be used as a guide for grinding the
+point of a thread-cutting tool. The cross level which is shown at B is
+of marked utility in erecting, as it will indicate absolutely if the
+piece it is used to test is level. It will indicate if the piece is
+level along its width as well as its length.
+
+[Illustration: Fig. 177.--Measuring Appliances of Value in Airplane
+Repair Work.]
+
+A very simple attachment for use with a scale that enables the machinist
+to scribe lines along the length of a cylindrical piece is shown at Fig.
+177, C. These are merely small wedge-shaped clamps having an angular
+face to rest upon the bars. The thread pitch gauge which is shown at
+Fig. 177, D, is an excellent pocket tool for the mechanic, as it is
+often necessary to determine without loss of time the pitch of the
+thread on a bolt or in a nut. This consists of a number of leaves having
+serrations on one edge corresponding to the standard thread it is to be
+used in measuring. The tool shown gives all pitches up to 48 threads per
+inch. The leaves may be folded in out of the way when not in use, and
+their shape admits of their being used in any position without the
+remainder of the set interfering with the one in use. The fine pitch
+gauges have slim, tapering leaves of the correct shape to be used in
+finding the pitch of small nuts. As the tool is round when the leaves
+are folded back out of the way, it is an excellent pocket tool, as there
+are no sharp corners to wear out the pocket. Practical application of a
+Vernier having measuring heads of special form for measuring gear teeth
+is shown at Fig. 176, A. As the action of this tool has been previously
+explained, it will not be necessary to describe it further.
+
+
+MICROMETER CALIPERS AND THEIR USE
+
+Where great accuracy is necessary in taking measurements the micrometer
+caliper, which in the simple form will measure easily .001 inch
+(one-thousandth part of an inch) and when fitted with a Vernier that
+will measure .0001 inch (one ten-thousandth part of an inch), is used.
+The micrometer may be of the caliper form for measuring outside
+diameters or it may be of the form shown at Fig. 176, B, for measuring
+internal diameters. The operation of both forms is identical except that
+the internal micrometer is placed inside of the bore to be measured
+while the external form is used just the same as a caliper. The form
+outlined will measure from one and one-half to six and a half inches as
+extension points are provided to increase the range of the instrument.
+The screw has a movement of one-half inch and a hardened anvil is placed
+in the end of the thimble in order to prevent undue wear at that point.
+The extension points or rods are accurately made in standard lengths and
+are screwed into the body of the instrument instead of being pushed in,
+this insuring firmness and accuracy. Two forms of micrometers for
+external measurements are shown at Fig. 178. The top one is graduated
+to read in thousandths of an inch, while the lower one is graduated to
+indicate hundredths of a millimeter. The mechanical principle involved
+in the construction of a micrometer is that of a screw free to move in a
+fixed nut. An opening to receive the work to be measured is provided by
+the backward movement of the thimble which turns the screw and the size
+of the opening is indicated by the graduations on the barrel.
+
+[Illustration: Fig. 178.--Standard Forms of Micrometer Caliper for
+External Measurements.]
+
+The article to be measured is placed between the anvil and spindle, the
+frame being held stationary while the thimble is revolved by the thumb
+and finger. The pitch of the screw thread on the concealed part of the
+spindle is 40 to an inch. One complete revolution of the spindle,
+therefore, moves it longitudinally one-fortieth, or twenty-five
+thousandths of an inch. As will be evident from the development of the
+scale on the barrel of the inch micrometer, the sleeve is marked with
+forty lines to the inch, each of these lines indicating twenty-five
+thousandths. The thimble has a beveled edge which is graduated into
+twenty-five parts. When the instrument is closed the graduation on the
+beveled edge of the thimble marked 0 should correspond to the 0 line on
+the barrel. If the micrometer is rotated one full turn the opening
+between the spindle and anvil will be .025 inch. If the thimble is
+turned only one graduation, or one twenty-fifth of a revolution, the
+opening between the spindle and anvil will be increased only by .001
+inch (one-thousandth of an inch).
+
+As many of the dimensions of the airplane parts, especially of those of
+foreign manufacture or such parts as ball and roller bearings, are based
+on the metric system, the competent repairman should possess both inch
+and metric micrometers in order to avoid continual reference to a table
+of metric equivalents. With a metric micrometer there are fifty
+graduations on the barrel, these representing .01 of a millimeter, or
+approximately .004 inch. One full turn of the barrel means an increase
+of half a millimeter, or .50 mm. (fifty one-hundredths). As it takes two
+turns to augment the space between the anvil and the stem by increments
+of one millimeter, it will be evident that it would not be difficult to
+divide the spaces on the metric micrometer thimble in halves by the eye,
+and thus the average workman can measure to .0002 inch plus or minus
+without difficulty. As set in the illustration, the metric micrometers
+show a space of 13.5 mm., or about one millimeter more than half an
+inch. The inch micrometer shown is set to five-tenths or five hundred
+one-thousandths or one-half inch. A little study of the foregoing matter
+will make it easy to understand the action of either the inch or metric
+micrometer.
+
+Both of the micrometers shown have a small knurled knob at the end of
+the barrel. This controls the ratchet stop, which is a device that
+permits a ratchet to slip by a pawl when more than a certain amount of
+pressure is applied, thereby preventing the measuring spindle from
+turning further and perhaps springing the instrument. A simple rule that
+can be easily memorized for reading the inch micrometer is to multiply
+the number of vertical divisions on the sleeve by 25 and add to that the
+number of divisions on the bevel of the thimble reading from the zero to
+the line which coincides with the horizontal line on the sleeve. For
+example: if there are ten divisions visible on the sleeve, multiply this
+number by 25, then add the number of divisions shown on the bevel of the
+thimble, which is 10. The micrometer is therefore opened 10 × 25 equals
+250 plus 10 equals 260 thousandths.
+
+Micrometers are made in many sizes, ranging from those having a maximum
+opening of one inch to special large forms that will measure forty or
+more inches. While it is not to be expected that the repairman will have
+use for the big sizes, if a caliper having a maximum opening of six
+inches is provided with a number of extension rods enabling one to
+measure smaller objects, practically all of the measuring needed in
+repairing engine parts can be made accurately. Two or three smaller
+micrometers having a maximum range of two or three inches will also be
+found valuable, as most of the measurements will be made with these
+tools which will be much easier to handle than the larger sizes.
+
+
+TYPICAL TOOL OUTFITS
+
+The equipment of tools necessary for repairing airplane engines depends
+entirely upon the type of the power plant and while the common hand
+tools can be used on all forms, the work is always facilitated by having
+special tools adapted for reaching the nuts and screws that would be
+hard to reach otherwise. Special spanners and socket wrenches are very
+desirable. Then again, the nature of the work to be performed must be
+taken into consideration. Rebuilding or overhauling an engine calls for
+considerably more tools than are furnished for making field repairs or
+minor adjustments. A complete set of tools supplied to men working on
+Curtiss OX-2 engines and JN-4 training biplanes is shown at Fig. 179.
+The tools are placed in a special box provided with a hinged cover and
+are arranged in the systematic manner outlined. The various tools and
+supplies shown are: A, hacksaw blades; B, special socket wrenches for
+engine bolts and nuts; C, ball pein hammers, four sizes; D, five
+assorted sizes of screw drivers ranging from very long for heavy work to
+short and small for fine work; E, seven pairs of pliers including
+combination in three sizes, two pairs of cutting pliers and one round
+nose; F, two split pin extractors and spreaders; G, wrench set including
+three adjustable monkey wrenches, one Stillson or pipe wrench, five
+sizes adjustable end wrenches and ten double end S wrenches; H, set of
+files, including flat, three cornered and half round; I, file brush; J,
+chisel and drift pin; K, three small punches or drifts; L, hacksaw
+frame; M, soldering copper; N, special spanners for propeller retaining
+nuts; O, special spanners; P, socket wrenches, long handle; Q, long
+handle, stiff bristle brushes for cleaning motor; R, gasoline blow
+torch; S, hand drill; T, spools of safety wire; U, flash lamp; V,
+special puller and castle wrenches; W, oil can; X, large adjustable
+monkey wrench; Y, washer and gasket cutter; Z, ball of heavy twine. In
+addition to the tools, various supplies, such as soldering acid, solder,
+shellac, valve grinding compound, bolts and nuts, split pins, washers,
+wood screws, etc., are provided.
+
+[Illustration: Fig. 179.--Special Tools for Maintaining Curtiss OX-2
+Motor Used in Curtiss JN-4 Training Biplane.]
+
+
+SPECIAL HALL-SCOTT TOOLS
+
+  NO.             TOOL                        DIRECTIONS FOR USE
+   1  Engine hoisting hook, 6-cylinder  Hook under cam-shaft housing,
+                                        when hoisting engine.
+   2  Engine hoisting hook, 4-cylinder  Hook under cam-shaft housing,
+                                        when hoisting engine.
+   3  Water plug wrench                 For use on water plugs on top
+                                        and end of cylinders.
+   4  Vertical shaft flange puller      For pulling lower pinion shaft
+                                        flange from shaft. (Used on A-5
+                                        and A-7 engines only.)
+   5  Oil gun                           For general lubrication use.
+   6  Magneto gear puller               For pulling magneto gears from
+                                        magneto shaft.
+   7  Socket wrench, 1/4" A.L.A.M.      For use on bolts and nuts on
+                                        crank cases.
+   8  Socket wrench, 1/4" A.L.A.M       For use on crank cases and
+                                        magneto gear housings.
+   9  Socket wrench, 1/4" A.L.A.M.      For use on magneto gear
+                                        housings.
+  10  Socket wrench, 3/8" standard      For bolts and nuts which fasten
+                                        magnetos to crank-case.
+  11  Socket wrench, 1/4" A.L.A.M.      For use on magneto gear
+                                        housings.
+  12  Vertical shaft gear puller        For removing water pump and
+                                        magneto drive gear.
+  13  Brace and facing cutter           For facing lugs on cylinders for
+                                        cylinder hold down stud washers.
+  14  Handle for brace                  Use with brace.
+  15  Valve grinding brace              For grinding in valves.
+  16  Socket wrench base, 3/8" A.L.A.M. For thrust bearing cap screws.
+  17  Brace and facing cutter, 5/16"    For facing lugs on rocker arm
+      A.L.A.M.                          covers.
+  18  Valve grinding screw driver       For grinding in valves.
+  19  Valve spring tool                 For putting on and taking off
+                                        valve springs.
+  20  Block-valve spring tool           For use with valve spring tool.
+  21  Socket wrench, 5/8" A.L.A.M.      For main bearing nuts.
+  22  Socket wrench, 1/4" A.L.A.M.      For use on cam-shaft housing.
+  23  Socket wrench, 5/16" A.L.A.M.     For cam-shaft housing hold down
+                                        stud nuts.
+  24  Socket wrench, 1/2" A.L.A.M.      For cylinder hold down stud
+                                        nuts.
+  25  Socket wrench, 5/16" A.L.A.M.     For carburetor and water pump
+                                        bolts and nuts.
+  26  Socket wrench, 5/16" A.L.A.M.     For carburetor and water pump
+                                        bolts and nuts.
+  27  Socket wrench                     For use on carburetor jets.
+  28  Magneto screw driver              For general magneto use.
+  29  Brass bar, 1" diameter × 7" long  For driving piston pins from
+                                        pistons.
+  30  Hack saw                          For general use.
+  31  Oil can                           For cam-shaft housing
+                                        lubrication.
+  32  Gasoline or distillate can        For priming or other use.
+  33  Oil can                           For magneto gear lubrication.
+  34  Shellac can                       For rubber hose connections and
+                                        gaskets.
+  35  Magneto cleaner                   For use on magnetos.
+  36  Clamps                            For holding cylinder hold down
+                                        studs, when fitting main
+                                        bearings.
+  37  Piston guards                     For use in pistons, when out of
+                                        engine, to protect them.
+  38  Screw driver                      For general use.
+  39  Vertical shaft clamps             For clamping vertical shaft
+                                        flanges, when timing engine.
+  40  Thrust adjusting nut wrench       For adjusting propeller thrust
+                                        bearing.
+  41  Stuffing box spanner wrench       For adjusting stuffing box nut
+                                        on vertical shaft.
+  42  Water pump spanner wrench         For adjusting water pump
+                                        stuffing nut.
+  43  Wrench                            For use on cylinder relief cocks
+                                        and cylinder priming cocks.
+  44  Hose clamp wrench                 For use on hose clamps.
+  45  Scraper                           For cleaning piston ring grooves
+                                        on pistons.
+  46  Crank-shaft nut wrench            For adjusting crank-shaft nut.
+  47  Spark-plug wrench                 For putting in and taking out
+                                        spark-plugs in cylinders.
+  48  Timing disc (single disc)         For use on crank-shaft to time
+                                        engine.
+      Specify type motor disc should be made for. If double disc is
+      required, specify the two types of motors the disc is to be made
+      for. Double disc.
+  49  Main bearing scraper              For scraping in bearings.
+  50  Cylinder carbon scraper           For removing carbon from heads
+                                        of cylinders.
+  51  Valve seating tool                For seating valves in cylinder
+                                        heads.
+  52  Scraper, small                    For general bearing use.
+  53  Scraper, large                    For general bearing use.
+  54  Crank-shaft flange puller         For pulling crank-shaft flange
+                                        from crank-shaft.
+  55  Piston and connecting rod racks.
+  56  Main bearing stud nuts and shim
+      rack.
+  57  Main bearing board rack.
+  58  Rocker arm and cover rack.
+
+The special tools and fixtures recommended by the Hall-Scott Company for
+work on their engines are clearly shown at Fig. 180. All tools are
+numbered and their uses may be clearly understood by reference to the
+illustration and explanatory list given on pages 410 and 411.
+
+
+OVERHAULING AIRPLANE ENGINES
+
+After an airplane engine has been in use for a period ranging from 60 to
+80 hours, depending upon the type, it is necessary to give it a thorough
+overhauling before it is returned to service. To do this properly, the
+engine is removed from the fuselage and placed on a special supporting
+stand, such as shown at Fig. 181, so it can be placed in any position
+and completely dismantled. With a stand of this kind it is as easy to
+work on the bottom of the engine as on the top and every part can be
+instantly reached. The crank-case shown in place in illustration is in a
+very convenient position for scraping in the crank-shaft bearings.
+
+[Illustration: Fig. 180.--Special Tools and Appliances to Facilitate
+Overhauling Work on Hall-Scott Airplane Engines.]
+
+In order to look over the parts of an engine and to restore the worn or
+defective components it is necessary to take the engine entirely apart,
+as it is only when the power plant is thoroughly dismantled that the
+parts can be inspected or measured to determine defects or wear. If one
+is not familiar with the engine to be inspected, even though the work is
+done by a repairman of experience, it will be found of value to take
+certain precautions when dismantling the engine in order to insure that
+all parts will be replaced in the same position they occupied before
+removal. There are a number of ways of identifying the parts, one of the
+simplest and surest being to mark them with steel numbers or letters or
+with a series of center punch marks in order to retain the proper
+relation when reassembling. This is of special importance in connection
+with dismantling multiple cylinder engines as it is vital that pistons,
+piston rings, connecting rods, valves, and other cylinder parts be
+always replaced in the same cylinder from which they were removed,
+because it is uncommon to find equal depreciation in all cylinders. Some
+repairmen use small shipping tags to identify the pieces. This can be
+criticised because the tags may become detached and lost and the
+identity of the piece mistaken. If the repairing is being done in a shop
+where other engines of the same make are being worked on, the repairman
+should be provided with a large chest fitted with a lock and key in
+which all of the smaller parts, such as rods, bolts and nuts, valves,
+gears, valve springs, cam-shafts, etc., may be stored to prevent the
+possibility of confusion with similar members of other engines. All
+parts should be thoroughly cleaned with gasoline or in the potash kettle
+as removed, and wiped clean and dry. This is necessary to show wear
+which will be evidenced by easily identified indications in cases where
+the machine has been used for a time, but in others, the deterioration
+can only be detected by delicate measuring instruments.
+
+[Illustration: Fig. 181.--Special Stand to Make Motor Overhauling Work
+Easier.]
+
+In taking down a motor the smaller parts and fittings such as
+spark-plugs, manifolds and wiring should be removed first. Then the more
+important members such as cylinders may be removed from the crank-case
+to give access to the interior and make possible the examination of the
+pistons, rings and connecting rods. After the cylinders are removed the
+next operation is to disconnect the connecting rods from the crank-shaft
+and to remove them and the pistons attached as a unit. Then the
+crank-case is dismembered, in most cases by removing the bottom half or
+oil sump, thus exposing the main bearings and crank-shaft. The first
+operation is the removal of the inlet and exhaust manifolds. In some
+cases the manifolds are cored integral with the cylinder head casting
+and it is merely necessary to remove a short pipe leading from the
+carburetor to one inlet opening and the exhaust pipe from the outlet
+opening common to all cylinders. In order to remove the carburetor it is
+necessary to shut off the gasoline supply at the tank and to remove the
+pipe coupling at the float chamber. It is also necessary to disconnect
+the throttle operating rod. After the cylinders are removed and before
+taking the crank-case apart it is well to remove the water pump and
+magneto. The wiring on most engines of modern development is carried in
+conduits and usually releasing two or three minor fastenings will permit
+one to take off the plug wiring as a unit. The wire should be
+disconnected from both spark-plugs and magneto distributor before its
+removal. When the cylinders are removed, the pistons, piston rings, and
+connecting rods are clearly exposed and their condition may be readily
+noticed.
+
+Before disturbing the arrangement of the timing gears, it is important
+that these be marked so that they will be replaced in exactly the same
+relation as intended by the engine designer. If the gears are properly
+marked the valve timing and magneto setting will be undisturbed when the
+parts are replaced after overhauling. With the cylinders off, it is
+possible to ascertain if there is any undue wear present in the
+connecting rod bearings at either the wrist pin or crank-pin ends and
+also to form some idea of the amount of carbon deposits on the piston
+top and back of the piston rings. Any wear of the timing gears can also
+be determined. The removal of the bottom plate of the engine enables the
+repairman to see if the main bearings are worn unduly. Often bearings
+may be taken up sufficiently to eliminate all looseness. In other cases
+they may be worn enough so that careful refitting will be necessary.
+Where the crank-case is divided horizontally into two portions, the
+upper one serving as an engine base to which the cylinders and in fact
+all important working parts are attached, the lower portion performs the
+functions of an oil container and cover for the internal mechanism. This
+is the construction generally followed.
+
+
+DEFECTS IN CYLINDERS
+
+After the cylinders have been removed and stripped of all fittings, they
+should be thoroughly cleaned and then carefully examined for defects.
+The interior or bore should be looked at with a view of finding score
+marks, grooves, cuts or scratches in the interior, because there are
+many faults that may be ascribed to depreciation at this point. The
+cylinder bore may be worn out of round, which can only be determined by
+measuring with an internal caliper or dial indicator even if the
+cylinder bore shows no sign of wear. The flange at the bottom of the
+cylinder by which it is held to the engine base may be cracked. The
+water jacket wall may have opened up due to freezing of the jacket
+water at some time or other or it may be filled with scale and sediment
+due to the use of impure cooling water. The valve seat may be scored or
+pitted, while the threads holding the valve chamber cap may be worn so
+that the cap will not be a tight fit. The detachable head construction
+makes it possible to remove that member and obtain ready access to the
+piston tops for scraping out carbon without taking the main cylinder
+portion from the crank-case. When the valves need grinding the head may
+be removed and carried to the bench where the work may be performed with
+absolute assurance that none of the valve grinding compound will
+penetrate into the interior of the cylinder as is sometimes unavoidable
+with the I-head cylinder. If the cylinder should be scored, the water
+jacket and combustion head may be saved and a new cylinder casting
+purchased at considerably less cost than that of the complete unit
+cylinder.
+
+The detachable head construction has only recently been applied on
+airplane engines, though it was one of the earliest forms of automobile
+engine construction. In the early days it was difficult to procure
+gaskets or packings that would be both gas and water tight. The sheet
+asbestos commonly used was too soft and blew out readily. Besides a new
+gasket had to be made every time the cylinder head was removed. Woven
+wire and asbestos packings impregnated with rubber, red lead, graphite
+and other filling materials were more satisfactory than the soft sheet
+asbestos, but were prone to burn out if the water supply became low.
+Materials such as sheet copper or brass proved to be too hard to form a
+sufficiently yielding packing medium that would allow for the inevitable
+slight inaccuracies in machining the cylinder head and cylinder. The
+invention of the copper-asbestos gasket, which is composed of two sheets
+of very thin, soft copper bound together by a thin edging of the same
+material and having a piece of sheet asbestos interposed solved this
+problem. Copper-asbestos packings form an effective seal against leakage
+of water and a positive retention means for keeping the explosion
+pressure in the cylinder. The great advantage of the detachable head is
+that it permits of very easy inspection of the piston tops and
+combustion chamber and ready removal of carbon deposits.
+
+
+CARBON DEPOSITS, THEIR CAUSE AND PREVENTION
+
+Most authorities agree that carbon is the result of imperfect combustion
+of the fuel and air mixture as well as the use of lubricating oils of
+improper flash point. Lubricating oils that work by the piston rings may
+become decomposed by the great heat in the combustion chamber, but at
+the same time one cannot blame the lubricating oil for all of the carbon
+deposits. There is little reason to suspect that pure petroleum oil of
+proper body will deposit excessive amounts of carbon, though if the oil
+is mixed with castor oil, which is of vegetable origin, there would be
+much carbon left in the interior of the combustion chamber. Fuel
+mixtures that are too rich in gasoline also produce these undesirable
+accumulations.
+
+A very interesting chemical analysis of a sample of carbon scraped from
+the interior of a motor vehicle engine shows that ordinarily the
+lubricant is not as much to blame as is commonly supposed. The analysis
+was as follows:
+
+  Oil                          14.3%
+  Other combustible matter     17.9
+  Sand, clay, etc.             24.8
+  Iron oxide                   24.5
+  Carbonate of lime             8.9
+  Other constituents            9.6
+
+It is extremely probable that the above could be divided into two
+general classes, these being approximately 32.2% oil and combustible
+matter and a much larger proportion, or 67.8% of earthy matter. The
+presence of such a large percentage of earthy matter is undoubtedly due
+to the impurities in the air, such as road dust which has been sucked
+in through the carburetor. The fact that over 17% of the matter which is
+combustible was not of an oily nature lends strong support to this view.
+There would not be the amount of earthy material present in the carbon
+deposits of an airplane engine as above stated because the air is almost
+free from dust at the high altitudes planes are usually flown. One could
+expect to find more combustible and less earthy matter and the carbon
+would be softer and more easily removed. It is very good practice to
+provide a screen on the air intake to reduce the amounts of dust sucked
+in with the air as well as observing the proper precautions relative to
+supplying the proper quantities of air to the mixture and of not using
+any more oil than is needed to insure proper lubrication of the internal
+mechanism.
+
+
+USE OF CARBON SCRAPERS
+
+It is not unusual for one to hear an aviator complain that the engine he
+operates is not as responsive as it was when new after he has run it but
+relatively few hours. There does not seem to be anything actually wrong
+with the engine, yet it does not respond readily to the throttle and is
+apt to overheat. While these symptoms denote a rundown condition of the
+mechanism, the trouble is often due to nothing more serious than
+accumulations of carbon. The remedy is the removal of this matter out of
+place. The surest way of cleaning the inside of the motor thoroughly is
+to remove the cylinders, if these members are cast integrally with the
+head or of removing the head member if that is a separate casting, to
+expose all parts.
+
+In certain forms of cylinders, especially those of the L form, it is
+possible to introduce simple scrapers down through the valve chamber cap
+holes and through the spark-plug hole if this component is placed in the
+cylinder in some position that communicates directly to the interior of
+the cylinder or to the piston top. No claim can be made for originality
+or novelty of this process as is has been used for many years on large
+stationary engines. The first step is to dismantle the inlet and exhaust
+piping and remove the valve caps and valves, although if the deposit is
+not extremely hard or present in large quantities one can often
+manipulate the scrapers in the valve cap openings without removing
+either the piping or the valves. Commencing with the first cylinder, the
+crank-shaft is turned till the piston is at the top of its stroke, then
+the scraper may be inserted, and the operation of removing the carbon
+started by drawing the tool toward the opening. As this is similar to a
+small hoe, the cutting edge will loosen some of the carbon and will draw
+it toward the opening. A swab is made of a piece of cloth or waste
+fastened at the end of a wire and well soaked in kerosene to clean out
+the cylinder.
+
+When available, an electric motor with a length of flexible shaft and a
+small circular cleaning brush having wire bristles can be used in the
+interior of the engine. The electric motor need not be over one-eighth
+horse-power running 1,200 to 1,600 R. P. M., and the wire brush must, of
+course, be of such size that it can be easily inserted through the valve
+chamber cap. The flexible shaft permits one to reach nearly all parts of
+the cylinder interior without difficulty and the spreading out and
+flattening of the brush insures that considerable surface will be
+covered by that member.
+
+
+BURNING OUT CARBON WITH OXYGEN
+
+A process of recent development that gives very good results in removing
+carbon without disassembling the motor depends on the process of burning
+out that material by supplying oxygen to support the combustion and to
+make it energetic. A number of concerns are already offering apparatus
+to accomplish this work, and in fact any shop using an autogenous
+welding outfit may use the oxygen tank and reducing valve in connection
+with a simple special torch for burning the carbon. Results have
+demonstrated that there is little danger of damaging the motor parts,
+and that the cost of oxygen and labor is much lower than the old method
+of removing the cylinders and scraping the carbon out, as well as being
+very much quicker than the alternative process of using carbon solvent.
+The only drawback to this system is that there is no absolute insurance
+that every particle of carbon will be removed, as small protruding
+particles may be left at points that the flame does not reach and cause
+pre-ignition and consequent pounding, even after the oxygen treatment.
+It is generally known that carbon will burn in the presence of oxygen,
+which supports combustion of all materials, and this process takes
+advantage of this fact and causes the gas to be injected into the
+combustion chamber over a flame obtained by a match or wax taper.
+
+[Illustration: Fig. 182.--Showing Where Carbon Deposits Collect in
+Engine Combustion Chamber, and How to Burn Them Out with the Aid of
+Oxygen. A--Special Torch. B--Torch Coupled to Oxygen Tank. C--Torch in
+Use.]
+
+It is suggested by those favoring this process that the night before the
+oxygen is to be used the engine be given a conventional kerosene
+treatment. A half tumbler full of this liquid or of denatured alcohol is
+to be poured into each cylinder and permitted to remain there over
+night. As a precaution against fire, the gasoline is shut off from the
+carburetor before the torch is inserted in the cylinder and the motor
+started so that the gasoline in the pipe and carburetor float chamber
+will be consumed. Work is done on one cylinder at a time. A note of
+caution was recently sounded by a prominent spark-plug manufacturer
+recommending that the igniter member be removed from the cylinder in
+order not to injure it by the heat developed. The outfits on the market
+consist of a special torch having a trigger controlled valve and a
+length of flexible tubing such as shown at Fig. 182, A, and a regulating
+valve and oxygen tank as shown at B. The gauge should be made to
+register about twelve pounds pressure.
+
+The method of operation is very simple and is outlined at C. The burner
+tube is placed in the cylinder and the trigger valve is opened and the
+oxygen permitted to circulate in the combustion chamber. A lighted match
+or wax taper is dropped in the chamber and the injector tube is moved
+around as much as possible so as to cover a large area. The carbon takes
+fire and burns briskly in the presence of the oxygen. The combustion of
+the carbon is accompanied by sparks and sometimes by flame if the
+deposit is of an oily nature. Once the carbon begins to burn the
+combustion continues without interruption as long as the oxygen flows
+into the cylinder. Full instructions accompany each outfit and the
+amount of pressure for which the regulator should be set depends upon
+the design of the torch and the amount of oxygen contained in the
+storage tank.
+
+
+REPAIRING SCORED CYLINDERS
+
+If the engine has been run at any time without adequate lubrication, one
+or more of the cylinders may be found to have vertical scratches running
+up and down the cylinder walls. The depth of these will vary according
+to the amount of time the cylinder was without lubrication, and if the
+grooves are very deep the only remedy is to purchase a new member. Of
+course, if sufficient stock is available in the cylinder walls, the
+cylinders may be rebored and new pistons which are oversize, _i.e._,
+larger than standard, may be fitted. Where the scratches are not deep
+they may be ground out with a high speed emery wheel or lapped out if
+that type of machine is not available. Wrist pins have been known to
+come loose, especially when these are retained by set screws that are
+not properly locked, and as wrist-pins are usually of hardened steel it
+will be evident that the sharp edge of that member can act as a cutting
+tool and make a pronounced groove in the cylinder. Cylinder grinding is
+a job that requires skilled mechanics, but may be accomplished on any
+lathe fitted with an internal grinding attachment. While automobile
+engine cylinders usually have sufficient wall thickness to stand
+reboring, those of airplane engines seldom have sufficient metal to
+permit of enlarging the bore very much by a boring tool. A few
+thousandths of an inch may be ground out without danger, however. An
+airplane engine cylinder with deep grooves must be scrapped as a general
+rule.
+
+Where the grooves in the cylinder are not deep or where it has warped
+enough so the rings do not bear equally at all parts of the cylinder
+bore, it is possible to obtain a fairly accurate degree of finish by a
+lapping process in which an old piston is coated with a mixture of fine
+emery and oil and is reciprocated up and down in the cylinder as well as
+turned at the same time. This may be easily done by using a dummy
+connecting rod having only a wrist pin end boss, and of such size at the
+other end so that it can be held in the chuck of a drill press. The
+cylinder casting is firmly clamped on the drill press table by suitable
+clamping blocks, and a wooden block is placed in the combustion chamber
+to provide a stop for the piston at its lower extreme position. The back
+gears are put in and the drill chuck is revolved slowly. All the while
+that the piston is turning the drill chuck should be raised up and down
+by the hand feed lever, as the best results are obtained when the
+lapping member is given a combination of rotary and reciprocating
+motion.
+
+
+VALVE REMOVAL AND INSPECTION
+
+One of the most important parts of the gasoline engine and one that
+requires frequent inspection and refitting to keep in condition, is the
+mushroom or poppet valve that controls the inlet and exhaust gas flow.
+In overhauling it is essential that these valves be removed from their
+seatings and examined carefully for various defects which will be
+enumerated at proper time. The problem that concerns us now is the best
+method of removing the valve. These are held against the seating in the
+cylinder by a coil spring which exerts its pressure on the cylinder
+casting at the upper end and against a suitable collar held by a key at
+the lower end of the valve stem. In order to remove the valve it is
+necessary to first compress the spring by raising the collar and pulling
+the retaining key out of the valve stem. Many forms of valve spring
+lifters have been designed to permit ready removal of the valves.
+
+When the cylinder is of the valve in-the-head form, the method of valve
+removal will depend entirely upon the system of cylinder construction
+followed. In the Sturtevant cylinder design it is possible to remove the
+head from the cylinder castings and the valve springs may be easily
+compressed by any suitable means when the cylinder head is placed on the
+work bench where it can be easily worked on. The usual method is to
+place the head on a soft cloth with the valves bearing against the
+bench. The valve springs may then be easily pushed down with a simple
+forked lever and the valve stem key removed to release the valve spring
+collar. In the Curtiss OX-2 (see Fig. 182-1/2) and Hall-Scott engines it
+is not possible to remove the valves without taking the cylinder off
+the crank-case, because the valve seats are machined directly in the
+cylinder head and the valve domes are cast integrally with the cylinder.
+This means that if the valves need grinding the cylinder must be removed
+from the engine base to provide access to the valve heads which are
+inside of that member, and which cannot be reached from the outside as
+is true of the L-cylinder construction. In the Curtiss VX engines, the
+valves are carried in detachable cages which may be removed when the
+valves need attention.
+
+[Illustration: Fig. 182-1/2.--Part Sectional View, Showing Valve
+Arrangement in Cylinder of Curtiss OX-2 Aviation Engine.]
+
+
+RESEATING AND TRUING VALVES
+
+Much has been said relative to valve grinding, and despite the mass of
+information given in the trade prints it is rather amusing to watch the
+average repairman or the engine user who prides himself on maintaining
+his own motor performing this essential operation. The common mistakes
+are attempting to seat a badly grooved or pitted valve head on an
+equally bad seat, which is an almost hopeless job, and of using coarse
+emery and bearing down with all one's weight on the grinding tool with
+the hope of quickly wearing away the rough surfaces. The use of improper
+abrasive material is a fertile cause of failure to obtain a satisfactory
+seating. Valve grinding is not a difficult operation if certain
+precautions are taken before undertaking the work. The most important of
+these is to ascertain if the valve head or seat is badly scored or
+pitted. If such is found to be the case no ordinary amount of grinding
+will serve to restore the surfaces. In this event the best thing to do
+is to remove the valve from its seating and to smooth down both the
+valve head and the seat in the cylinder before attempt is made to fit
+them together by grinding. Another important precaution is to make sure
+that the valve stem is straight, and that the head is not warped out of
+shape.
+
+[Illustration: Fig. 183.--Tools for Restoring Valve Head and Seats.]
+
+A number of simple tools is available at the present time for reseating
+valves, these being outlined at Fig. 183. That shown at A is a simple
+fixture for facing off the valve head. The stem is supported by suitable
+bearings carried by the body or shank of the tool, and the head is
+turned against an angularly disposed cutter which is set for the proper
+valve seat angle. The valve head is turned by a screw-driver, the amount
+of stock removed from the head depending upon the location of the
+adjusting screw. Care must be taken not to remove too much metal, only
+enough being taken off to remove the most of the roughness. Valves are
+made in two standard tapers, the angle being either 45 or 60 degrees. It
+is imperative that the cutter blade be set correctly in order that the
+bevel is not changed. A set of valve truing and valve-seat reaming
+cutters is shown at Fig. 183, B. This is adaptable to various size valve
+heads, as the cutter blade D may be moved to correspond to the size of
+the valve head being trued up. These cutter blades are made of tool
+steel and have a bevel at each end, one at 45 degrees, the other at 60
+degrees. The valve seat reamer shown at G will take any one of the heads
+shown at F. It will also take any one of the guide bars shown at H. The
+function of the guide bars is to fit the valve stem bearing in order to
+locate the reamer accurately and to insure that the valve seat is
+machined concentrically with its normal center. Another form of valve
+seat reamer and a special wrench used to turn it is shown at C. The
+valve head truer shown at Fig. 183, D, is intended to be placed in a
+vise and is adaptable to a variety of valve head sizes. The smaller
+valves merely fit deeper in the conical depression. The cutter blade is
+adjustable and the valve stem is supported by a simple self-centering
+bearing. In operation it is intended that the valve stem, which
+protrudes through the lower portion of the guide bearing, shall be
+turned by a drill press or bit stock while the valve head is set against
+the cutter by pressure of a pad carried at the end of a feed screw which
+is supported by a hinged bridge member. This can be swung out of place
+as indicated to permit placing the valve head against the cutter or
+removing it.
+
+As the sizes of valve heads and stems vary considerably a "Universal"
+valve head truing tool must have some simple means of centering the
+valve stem in order to insure concentric machining of the valve head. A
+valve head truer which employs an ingenious method of guiding the valve
+stem is shown at Fig. 183, E. The device consists of a body portion, B,
+provided with an external thread at the top on which the cutter head, A,
+is screwed. A number of steel balls, C, are carried in the grooves which
+may be altered in size by the adjustment nut, F, which screws in the
+bottom of the body portion, B. As the nut F is screwed in against the
+spacer member E, the V-grooves are reduced in size and the steel balls,
+C, are pressed out in contact with the valve stem. As the circle or
+annulus is filled with balls in both upper and lower portions the stem
+may be readily turned because it is virtually supported by ball bearing
+guides. When a larger valve stem is to be supported, the adjusting nut
+F, is screwed out which increases the size of the grooves and permits
+the balls, C, to spread out and allow the larger stem to be inserted.
+
+
+VALVE GRINDING PROCESSES
+
+Mention has been previously made of the importance of truing both valve
+head and seat before attempt is made to refit the parts by grinding.
+After smoothing the valve seat the next step is to find some way of
+turning the valve. Valve heads are usually provided with a screw-driver
+slot passing through the boss at the top of the valve or with two
+drilled holes to take a forked grinding tool. A combination grinding
+tool has been devised which may be used when either the two drilled
+holes or the slotted head form of valve is to be rotated. This consists
+of a special form of screw driver having an enlarged boss just above the
+blade, this boss serving to support a U-shape piece which can be
+securely held in operative position by the clamp screw or which can be
+turned out of the way if the screw driver blade is to be used.
+
+As it is desirable to turn the valve through a portion of a revolution
+and back again rather than turning it always in the same direction, a
+number of special tools has been designed to make this oscillating
+motion possible without trouble. A simple valve grinding tool is shown
+at Fig. 184, C. This consists of a screw-driver blade mounted in a
+handle in such a way that the end may turn freely in the handle. A
+pinion is securely fastened to the screw-driver blade shank, and is
+adapted to fit a race provided with a wood handle and guided by a bent
+bearing member securely fastened to the screw-driver handle. As the rack
+is pushed back and forth the pinion must be turned first in one
+direction and then in the other.
+
+[Illustration: Fig. 184.--Tools and Processes Utilized in Valve
+Grinding.]
+
+A valve grinding tool patterned largely after a breast drill is shown at
+Fig. 184, D. This is worked in such a manner that a continuous rotation
+of the operating crank will result in an oscillating movement of the
+chuck carrying the screw-driver blade. The bevel pinions which are used
+to turn the chuck are normally free unless clutched to the chuck stem by
+the sliding sleeve which must turn with the chuck stem and which carries
+clutching members at each end to engage similar members on the bevel
+pinions and lock these to the chuck stem, one at a time. The bevel gear
+carries a cam-piece which moves the clutch sleeve back and forth as it
+revolves. This means that the pinion giving forward motion of the chuck
+is clutched to the chuck spindle for a portion of a revolution of the
+gear and clutch sleeve is moved back by the cam and clutched to the
+pinion giving a reverse motion of the chuck during the remainder of the
+main drive gear revolution.
+
+It sometimes happens that the adjusting screw on the valve lift plunger
+or the valve lift plunger itself when L head cylinders are used does not
+permit the valve head to rest against the seat. It will be apparent that
+unless a definite space exists between the end of the valve stem and the
+valve lift plunger that grinding will be of little avail because the
+valve head will not bear properly against the abrasive material smeared
+on the valve seat.
+
+The usual methods of valve grinding are clearly outlined at Fig. 184.
+The view at the left shows the method of turning the valve by an
+ordinary screw driver and also shows a valve head at A, having both the
+drilled holes and the screw-driver slot for turning the member and two
+special forms of fork-end valve grinding tools. In the sectional view
+shown at the right, the use of the light spring between the valve head
+and the bottom of the valve chamber to lift the valve head from the seat
+whenever pressure on the grinding tool is released is clearly indicated.
+It will be noted also that a ball of waste or cloth is interposed in the
+passage between the valve chamber and the cylinder interior to prevent
+the abrasive material from passing into the cylinder from the valve
+chamber. When a bitstock is used, instead of being given a true rotary
+motion the chuck is merely oscillated through the greater part of the
+circle and back again. It is necessary to lift the valve from its seat
+frequently as the grinding operation continues; this is to provide an
+even distribution of the abrasive material placed between the valve head
+and its seat. Only sufficient pressure is given to the bitstock to
+overcome the uplift of the spring and to insure that the valve will be
+held against the seat. Where the spring is not used it is possible to
+raise the valve from time to time with the hand which is placed under
+the valve stem to raise it as the grinding is carried on. It is not
+always possible to lift the valve in this manner when the cylinders are
+in place on the engine base owing to the space between the valve lift
+plunger and the end of the valve stem. In this event the use of the
+spring as shown in sectional view will be desirable.
+
+The abrasive generally used is a paste made of medium or fine emery and
+lard oil or kerosene. This is used until the surfaces are comparatively
+smooth, after which the final polish or finish is given with a paste of
+flour emery, grindstone dust, crocus, or ground glass and oil. An
+erroneous impression prevails in some quarters that the valve head
+surface and the seating must have a mirror-like polish. While this is
+not necessary it is essential that the seat in the cylinder and the
+bevel surface of the head be smooth and free from pits or scratches at
+the completion of the operation. All traces of the emery and oil should
+be thoroughly washed out of the valve chamber with gasoline before the
+valve mechanism is assembled and in fact it is advisable to remove the
+old grinding compound at regular intervals, wash the seat thoroughly and
+supply fresh material as the process is in progress.
+
+The truth of seatings may be tested by taking some Prussian blue pigment
+and spreading a thin film of it over the valve seat. The valve is
+dropped in place and is given about one-eighth turn with a little
+pressure on the tool. If the seating is good both valve head and seat
+will be covered uniformly with color. If high spots exist, the heavy
+deposit of color will show these while the low spots will be made
+evident because of the lack of pigment. The grinding process should be
+continued until the test shows an even bearing of the valve head at all
+points of the cylinder seating. When the valves are held in cages it is
+possible to catch the cage in a vise and to turn the valve in any of the
+ways indicated. It is much easier to clean off the emery and oil and
+there is absolutely no danger of getting the abrasive material in the
+cylinder if the construction is such that the valve cage or cylinder
+head member carrying the valve can be removed from the cylinder. When
+valves are held in cages, the tightness of the seat may be tested by
+partially filling the cage with gasoline and noticing how much liquid
+oozes out around the valve head. The degree of moisture present
+indicates the efficacy of the grinding process.
+
+The valves of Curtiss OX-2 cylinders are easily ground in by using a
+simple fixture or tool and working from the top of the cylinder instead
+of from the inside. A tube having a bore just large enough to go over
+the valve stem is provided with a wooden handle or taped at one end and
+a hole of the same size as that drilled through the valve stem is put in
+at the other. To use, the open end of the tube is pushed over the valve
+stem and a split pin pushed through the tube and stem. The valve may be
+easily manipulated and ground in place by oscillating in the customary
+manner.
+
+
+DEPRECIATION IN VALVE OPERATING SYSTEMS
+
+There are a number of points to be watched in the valve operating system
+because valve timing may be seriously interfered with if there is much
+lost motion at the various bearing points in the valve lift mechanism.
+The two conventional methods of opening valves are shown at Fig. 185.
+That at A is the type employed when the valve cages are mounted directly
+in the head, while the form at B is the system used when the valves are
+located in a pocket or extension of the cylinder casting as is the case
+if an L, or T-head cylinder is used. It will be evident that there are
+several points where depreciation may take place. The simplest form is
+that shown at B, and even on this there are five points where lost
+motion may be noted. The periphery of the valve opening cam or roller
+may be worn, though this is not likely unless the roller or cam has
+been inadvertently left soft. The pin which acts as a bearing for the
+roller may become worn, this occurring quite often. Looseness may
+materialize between the bearing surfaces of the valve lift plunger and
+the plunger guide casting, and there may also be excessive clearance
+between the top of the plunger and the valve stem.
+
+[Illustration: Fig. 185.--Outlining Points in Valve Operating Mechanism
+Where Depreciation is Apt to Exist.]
+
+On the form shown at A, there are several parts added to those indicated
+at B. A walking beam or rocker lever is necessary to transform the
+upward motion of the tappet rod to a downward motion of the valve stem.
+The pin on which this member fulcrums may wear as will also the other
+pin acting as a hinge or bearing for the yoke end of the tappet rod. It
+will be apparent that if slight play existed at each of the points
+mentioned it might result in a serious diminution of valve opening.
+Suppose, for example, that there were .005-inch lost motion at each of
+three bearing points, the total lost motion would be .015-inch or
+sufficient to produce noisy action of the valve mechanism. When valve
+plungers of the adjustable form, such as shown at B, are used, the
+hardened bolt head in contact with the end of the valve stem may become
+hollowed out on account of the hammering action at that point. It is
+imperative that the top of this member be ground off true and the
+clearance between the valve stem and plunger properly adjusted. If the
+plunger is a non-adjustable type it will be necessary to lengthen the
+valve stem by some means in order to reduce the excessive clearance. The
+only remedy for wear at the various hinges and bearing pins is to bore
+the holes out slightly larger and to fit new hardened steel pins of
+larger diameter. Depreciation between the valve plunger guide and the
+valve plunger is usually remedied by fitting new plunger guides in place
+of the worn ones. If there is sufficient stock in the plunger guide
+casting as is sometimes the case when these members are not separable
+from the cylinder casting, the guide may be bored out and bushed with a
+light bronze bushing.
+
+A common cause of irregular engine operation is due to a sticking valve.
+This may be owing to a bent valve stem, a weak or broken valve spring or
+an accumulation of burnt or gummed oil between the valve stem and the
+valve stem guide. In order to prevent this the valve stem must be
+smoothed with fine emery cloth and no burrs or shoulders allowed to
+remain on it, and the stem must also be straight and at right angles to
+the valve head. If the spring is weak it may be strengthened in some
+cases by stretching it out after annealing so that a larger space will
+exist between the coils and re-hardening. Obviously if a spring is
+broken the only remedy is replacement of the defective member.
+
+Mention has been made of wear in the valve stem guide and its influence
+on engine action. When these members are an integral part of the
+cylinder the only method of compensating for this wear is to drill the
+guide out and fit a bushing, which may be made of steel tube.
+
+In some engines, especially those of recent development, the valve stem
+guide is driven or screwed into the cylinder casting and is a separate
+member which may be removed when worn and replaced with a new one. When
+the guides become enlarged to such a point that considerable play exists
+between them and the valve stems, they may be easily knocked out or
+unscrewed.
+
+
+PISTON TROUBLES
+
+If an engine has been entirely dismantled it is very easy to examine the
+pistons for deterioration. While it is important that the piston be a
+good fit in the cylinder it is mainly upon the piston rings that
+compression depends. The piston should fit the cylinder with but little
+looseness, the usual practice being to have the piston about .001-inch
+smaller than the bore for each inch of piston diameter at the point
+where the least heat is present or at the bottom of the piston. It is
+necessary to allow more than this at the top of the piston owing to its
+expansion due to the direct heat of the explosion. The clearance is
+usually graduated and a piston that would be .005-inch smaller than the
+cylinder bore at the bottom would be about .0065-inch at the middle and
+.0075-inch at the top. If much more play than this is evidenced the
+piston will "slap" in the cylinder and the piston will be worn at the
+ends more than in the center. Aluminum or alloy pistons require more
+clearance than cast iron ones do, usually 1.50 times as much. Pistons
+sometimes warp out of shape and are not truly cylindrical. This results
+in the high spots rubbing on the cylinder while the low spots will be
+blackened where a certain amount of gas has leaked by.
+
+Mention has been previously made of the necessity of reboring or
+regrinding a cylinder that has become scored or scratched and which
+allows the gas to leak by the piston rings. When the cylinder is ground
+out, it is necessary to use a larger piston to conform to the enlarged
+cylinder bore. Most manufacturers are prepared to furnish over-size
+pistons, there being four standard over-size dimensions adopted by the
+S. A. E. for rebored cylinders. These are .010-inch, .020-inch,
+.030-inch, and .040-inch larger than the original bore.
+
+The piston rings should be taken out of the piston grooves and all
+carbon deposits removed from the inside of the ring and the bottom of
+the groove. It is important to take this deposit out because it prevents
+the rings from performing their proper functions by reducing the ring
+elasticity, and if the deposit is allowed to accumulate it may
+eventually result in sticking and binding of the ring, this producing
+excessive friction or loss of compression. When the rings are removed
+they should be tested to see if they retain their elasticity and it is
+also well to see that the small pins in some pistons which keep the
+rings from turning around so the joints will not come in line are still
+in place. If no pins are found there is no cause for alarm because these
+dowels are not always used. When fitted, they are utilized with rings
+having a butt joint or diagonal cut as the superior gas retaining
+qualities of the lap or step joint render the pins unnecessary.
+
+If gas has been blowing by the ring or if these members have not been
+fitting the cylinder properly the points where the gas passed will be
+evidenced by burnt, brown or roughened portions of the polished surface
+of the pistons and rings. The point where this discoloration will be
+noticed more often is at the thin end of an eccentric ring, the
+discoloration being present for about 1/2-inch or 3/4-inch each side of
+the slot. It may be possible that the rings were not true when first
+put in. This made it possible for the gas to leak by in small amounts
+initially which increased due to continued pressure until quite a large
+area for gas escape had been created.
+
+
+PISTON RING MANIPULATION
+
+Removing piston rings without breaking them is a difficult operation if
+the proper means are not taken, but is a comparatively simple one when
+the trick is known. The tools required are very simple, being three
+strips of thin steel about one-quarter inch wide and four or five inches
+long and a pair of spreading tongs made up of one-quarter inch diameter
+keystock tied in the center with a copper wire to form a hinge. The
+construction is such that when the hand is closed and the handles
+brought together the other end of the expander spreads out, an action
+just opposite to that of the conventional pliers. The method of using
+the tongs and the metal strips is clearly indicated at Fig. 186. At A
+the ring expander is shown spreading the ends of the rings sufficiently
+to insert the pieces of sheet metal between one of the rings and the
+piston. Grasp the ring as shown at B, pressing with the thumbs on the
+top of the piston and the ring will slide off easily, the thin metal
+strips acting as guide members to prevent the ring from catching in the
+other piston grooves. Usually no difficulty is experienced in removing
+the top or bottom rings, as these members may be easily expanded and
+worked off directly without the use of a metal strip. When removing the
+intermediate rings, however, the metal strips will be found very useful.
+These are usually made by the repairman by grinding the teeth from old
+hacksaw blades and rounding the edges and corners in order to reduce the
+liability of cutting the fingers. By the use of the three metal strips a
+ring is removed without breaking or distorting it and practically no
+time is consumed in the operation.
+
+
+FITTING PISTON RINGS
+
+Before installing new rings, they should be carefully fitted to the
+grooves to which they are applied. The tools required are a large piece
+of fine emery cloth, a thin, flat file, a small vise with copper or
+leaden jaw clips, and a smooth hard surface such as that afforded by the
+top of a surface plate or a well planed piece of hard wood. After making
+sure that all deposits of burnt oil and carbon have been removed from
+the piston grooves, three rings are selected, one for each groove. The
+ring is turned all around its circumference into the groove it is to
+fit, which can be done without springing it over the piston as the
+outside edge of the ring may be used to test the width of the groove
+just as well as the inside edge. The ring should be a fair fit and while
+free to move circumferentially there should be no appreciable up and
+down motion. If the ring is a tight fit it should be laid edge down upon
+the piece of emery cloth which is placed on the surface plate and
+carefully rubbed down until it fits the groove it is to occupy. It is
+advisable to fit each piston ring individually and to mark them in some
+way to insure that they will be placed in the groove to which they are
+fitted.
+
+The repairman next turns his attention to fitting the ring in the
+cylinder itself. The ring should be pushed into the cylinder at least
+two inches up from the bottom and endeavor should be made to have the
+lower edge of the ring parallel with the bottom of the cylinder. If the
+ring is not of correct diameter, but is slightly larger than the
+cylinder bore, this condition will be evident by the angular slots of
+the rings being out of line or by difficulty in inserting the ring if it
+is a lap joint form. If such is the case the ring is removed from the
+cylinder and placed in the vise between soft metal jaw clips. Sufficient
+metal is removed with a fine file from the edges of the ring at the slot
+until the edges come into line and a slight space exists between them
+when the ring is placed into the cylinder. It is important that this
+space be left between the ends, for if this is not done when the ring
+becomes heated the expansion of metal may cause the ends to abut and the
+ring to jam in the cylinder.
+
+[Illustration: Fig. 186.--Method of Removing Piston Rings, and Simple
+Clamp to Facilitate Insertion of Rings in Cylinder.]
+
+It is necessary to use more than ordinary caution in replacing the rings
+on the piston because they are usually made of cast iron, a metal that
+is very fragile and liable to break because of its brittleness. Special
+care should be taken in replacing new rings as these members are more
+apt to break than old ones. This is probably accounted for by the
+heating action on used rings which tends to anneal the metal as well as
+making it less springy. The bottom ring should be placed in position
+first which is easily accomplished by springing the ring open enough to
+pass on the piston and then sliding it into place in the lower groove
+which on some types of engines is below the wrist pin, whereas in others
+all grooves are above that member. The other members are put in by a
+reversal of the process outlined at Fig. 186, A and B. It is not always
+necessary to use the guiding strips of metal when replacing rings as it
+is often possible, by putting the rings on the piston a little askew and
+maneuvering them to pass the grooves without springing the ring into
+them. The top ring should be the last one placed in position.
+
+Before placing pistons in the cylinder one should make sure that the
+slots in the piston rings are spaced equidistant on the piston, and if
+pins are used to keep the ring from turning one should be careful to
+make sure that these pins fit into their holes in the ring and that they
+are not under the ring at any point. Practically all cylinders are
+chamfered at the lower end to make insertion of piston rings easier. The
+operation of putting on a cylinder casting over a piston really requires
+two pairs of hands, one to manipulate the cylinder, the other person to
+close the rings as they enter the cylinder. This may be done very easily
+by a simple clamp member made of sheet brass or iron and used to close
+the ring as indicated at Fig. 186, C. It is apparent that the clamp must
+be adjusted to each individual ring and that the split portion of the
+clamp must coincide with the split portion of the ring. The cylinder
+should be well oiled before any attempt is made to install the pistons.
+The engine should be run with more than the ordinary amount of lubricant
+for several hours after new piston rings have been inserted. On first
+starting the engine, one may be disappointed in that the compression is
+even less than that obtained with the old rings. This condition will
+soon be remedied as the rings become polished and adapt themselves to
+the contour of the cylinder.
+
+
+WRIST PIN WEAR
+
+While wrist pins are usually made of very tough steel, case hardened
+with the object of wearing out an easily renewable bronze bushing in the
+upper end of the connecting rod rather than the wrist pin it sometimes
+happens that these members will be worn so that even the replacement of
+a new bushing in the connecting rod will not reduce the lost motion and
+attendant noise due to a loose wrist pin. The only remedy is to fit new
+wrist pins to the piston. Where the connecting rod is clamped to the
+wrist pin and that member oscillates in the piston bosses the wear will
+usually be indicated on bronze bushings which are pressed into the
+piston bosses. These are easily renewed and after running a reamer
+through them of the proper size no difficulty should be experienced in
+replacing either the old or a new wrist pin depending upon the condition
+of that member. If no bushings are provided, as in alloy pistons, the
+bosses can sometimes be bored out and thin bushings inserted, though
+this is not always possible. The alternative is to ream out the bosses
+and upper end of rod a trifle larger after holes are trued up and fit
+oversize wrist pins.
+
+
+INSPECTION AND REFITTING OF ENGINE BEARINGS
+
+While the engine is dismantled one has an excellent opportunity to
+examine the various bearing points in the engine crank-case to ascertain
+if any looseness exists due to depreciation of the bearing surfaces. As
+will be evident, both main crank-shaft bearings and the lower end of the
+connecting rods may be easily examined for deterioration. With the rods
+in place, it is not difficult to feel the amount of lost motion by
+grasping the connecting rod firmly with the hand and moving it up and
+down. After the connecting rods have been removed and the propeller hub
+taken off the crank-shaft to permit of ready handling, any looseness in
+the main bearing may be detected by lifting up on either the front or
+rear end of the crank-shaft and observing if there is any lost motion
+between the shaft journal and the main bearing caps. It is not necessary
+to take an engine entirely apart to examine the main bearings, as in
+most forms these may be readily reached by removing the sump. The
+symptoms of worn main bearings are not hard to identify. If an engine
+knocks regardless of speed or spark-lever position, and the trouble is
+not due to carbon deposits in the combustion chamber, one may reasonably
+surmise that the main bearings have become loose or that lost motion may
+exist at the connecting rod big ends, and possibly at the wrist pins.
+The main journals of any well resigned engine are usually proportioned
+with ample surface and will not wear unduly unless lubrication has been
+neglected. The connecting rod bearings wear quicker than the main
+bearings owing to being subjected to a greater unit stress, and it may
+be necessary to take these up.
+
+
+ADJUSTING MAIN BEARINGS
+
+[Illustration: Fig. 187.--Tools and Processes Used in Refitting Engine
+Bearings.]
+
+When the bearings are not worn enough to require refitting the lost
+motion can often be eliminated by removing one or more of the thin shims
+or liners ordinarily used to separate the bearing caps from the seat.
+These are shown at Fig. 187, A. Care must be taken that an even number
+of shims of the same thickness are removed from each side of the
+journal. If there is considerable lost motion after one or two shims
+have been removed, it will be advisable to take out more shims and to
+scrape the bearing to a fit before the bearing cap is tightened up. It
+may be necessary to clean up the crank-shaft journals as these may be
+scored due to not having received clean oil or having had bearings seize
+upon them. It is not difficult to true up the crank-pins or main
+journals if the score marks are not deep. A fine file and emery cloth
+may be used, or a lapping tool such as depicted at Fig. 187, B. The
+latter is preferable because the file and emery cloth will only tend to
+smooth the surface while the lap will have the effect of restoring the
+crank to proper contour.
+
+A lapping tool may be easily made, as shown at B, the blocks being of
+lead or hard wood. As the width of these are about half that of the
+crank-pin the tool may be worked from side to side as it is rotated. An
+abrasive paste composed of fine emery powder and oil is placed between
+the blocks, and the blocks are firmly clamped to the crank-pin. As the
+lead blocks bed down, the wing nut should be tightened to insure that
+the abrasive will be held with some degree of pressure against the
+shaft. A liberal supply of new abrading material is placed between the
+lapping blocks and crank-shaft from time to time and the old mixture
+cleaned off with gasoline. It is necessary to maintain a side to side
+movement of the lapping tool in order to have the process affect the
+whole width of the crank-pin equally. The lapping is continued until a
+smooth surface is obtained. If a crank-pin is worn out of true to any
+extent the only method of restoring it is to have it ground down to
+proper circular form by a competent mechanic having the necessary
+machine tools to carry on the work accurately. A crank-pin truing tool
+that may be worked by hand is shown at Fig. 187, K.
+
+After the crank-shaft is trued the next operation is to fit it to the
+main bearings or rather to scrape these members to fit the shaft
+journal. In order to bring the brasses closer together, it may be
+necessary to remove a little metal from the edges of the caps to
+compensate for the lost motion. A very simple way of doing this is shown
+at Fig. 187, D. A piece of medium emery cloth is rested on the surface
+plate and the box or brass is pushed back and forth over that member by
+hand, the amount of pressure and rapidity of movement being determined
+by the amount of metal it is necessary to remove. This is better than
+filing, because the edges will be flat and there will be no tendency
+for the bearing caps to rock when placed against the bearing seat. It is
+important to take enough off the edges of the boxes to insure that they
+will grip the crank tightly. The outer diameter must be checked with a
+pair of calipers during this operation to make sure that the surfaces
+remain parallel. Otherwise, the bearing brasses will only grip at one
+end and with such insufficient support they will quickly work loose,
+both in the bearing seat and bearing cap.
+
+
+SCRAPING BRASSES TO FIT
+
+To insure that the bearing brasses will be a good fit on the trued-up
+crank-pins or crank-shaft journals, they must be scraped to fit the
+various crank-shaft journals. The process of scraping, while a tedious
+one, is not difficult, requiring only patience and some degree of care
+to do a good job. The surface of the crank-pin is smeared with Prussian
+blue pigment which is spread evenly over the entire surface. The
+bearings are then clamped together in the usual manner with the proper
+bolts, and the crank-shaft revolved several times to indicate the high
+spots on the bearing cap. At the start of the process of scraping in,
+the bearing may seat only at a few points as shown at Fig. 187, G.
+Continued scraping will bring the bearing surface as indicated at H,
+which is a considerable improvement, while the process may be considered
+complete when the brass indicates a bearing all over as at I. The high
+spots are indicated by blue, as where the shaft does not bear on the
+bearing there is no color. The high spots are removed by means of a
+scraping tool of the form shown at Fig. 187, F, which is easily made
+from a worn-out file. These are forged to shape and ground hollow as
+indicated in the section, and are kept properly sharpened by frequent
+rubbing on an ordinary oil stone. To scrape properly, the edge of the
+scraper must be very keen. The straight and curved half-round scrapers,
+shown at M and N, are used for bearings. The three-cornered scraper,
+outlined at O, is also used on curved surfaces, and is of value in
+rounding off the sharp corners. The straight or curved half-round type
+works well on soft-bearing metals, such as babbitt, or white brass, but
+on yellow brass or bronze it cuts very slowly, and as soon as the edge
+becomes dull considerable pressure is needed to remove any metal, this
+calling for frequent sharpening.
+
+When correcting errors on flat or curved surfaces by hand-scraping, it
+is desirable, of course, to obtain an evenly spotted bearing with as
+little scraping as possible. When the part to be scraped is first
+applied to the surface-plate, or to a journal in the case of a bearing,
+three or four "high" spots may be indicated by the marking material. The
+time required to reduce these high spots and obtain a bearing that is
+distributed over the entire surface depends largely upon the way the
+scraping is started. If the first bearing marks indicate a decided rise
+in the surface, much time can be saved by scraping larger areas than are
+covered by the bearing marks; this is especially true of large shaft and
+engine bearings, etc. An experienced workman will not only remove the
+heavy marks, but also reduce a larger area; then, when the bearing is
+tested again, the marks will generally be distributed somewhat. If the
+heavy marks which usually appear at first are simply removed by light
+scraping, these "point bearings" are gradually enlarged, but a much
+longer time will be required to distribute them.
+
+The number of times the bearing must be applied to the journal for
+testing is important, especially when the box or bearing is large and
+not easily handled. The time required to distribute the bearing marks
+evenly depends largely upon one's judgment in "reading" these marks. In
+the early stages of the scraping operation, the marks should be used
+partly as a guide for showing the high areas, and instead of merely
+scraping the marked spot the surface surrounding it should also be
+reduced, unless it is evident that the unevenness is local. The idea
+should be to obtain first a few large but generally distributed marks;
+then an evenly and finely spotted surface can be produced quite easily.
+
+In fitting brasses when these are of the removable type, two methods may
+be used. The upper half of the engine base may be inverted on a suitable
+bench or stand and the boxes fitted by placing the crank-shaft in
+position, clamping down one bearing cap at a time and fitting each
+bearing in succession until they bed equally. From that time on the
+bearings should be fitted at the same time so the shaft will be parallel
+with the bottom of the cylinders. Considerable time and handling of the
+heavy crank-shaft may be saved if a preliminary fitting of the bearing
+brasses is made by clamping them together with a carpenter's wood clamp
+as shown at Fig. 187, J, and leaving the crank-shaft attached to the
+bench as shown at C. The brasses are revolved around the crank-shaft
+journal and are scraped to fit wherever high spots are indicated until
+they begin to seat fairly. When the brasses assume a finished appearance
+the final scraping should be carried on with all bearings in place and
+revolving the crank-shaft to determine the area of the seating. When the
+brasses are properly fitted they will not only show a full bearing
+surface, but the shaft will not turn unduly hard if revolved with a
+moderate amount of leverage.
+
+Bearings of white metal or babbitt can be fitted tighter than those of
+bronze, and care must be observed in supplying lubricant as considerably
+more than the usual amount is needed until the bearings are run in by
+several hours of test block work. Before the scraping process is started
+it is well to chisel an oil groove in the bearing as shown at Fig. 187,
+L. Grooves are very helpful in insuring uniform distribution of oil over
+the entire width of bearing and at the same time act as reservoirs to
+retain a supply of oil. The tool used is a round-nosed chisel, the
+effort being made to cut the grooves of uniform depth and having smooth
+sides. Care should be taken not to cut the grooves too deeply, as this
+will seriously reduce the strength of the bearing bushing. The shape of
+the groove ordinarily provided is clearly shown at Fig. 187, G, and it
+will be observed that the grooves do not extend clear to the edge of the
+bearing, but stop about a quarter of an inch from that point. The hole
+through which the oil is supplied to the bearing is usually drilled in
+such a way that it will communicate with the groove.
+
+The tool shown at Fig. 187, K, is of recent development, and is known as
+a "crank-shaft equalizer." This is a hand-operated turning tool,
+carrying cutters which are intended to smooth down scored crank-pins
+without using a lathe. The feed may be adjusted by suitable screws and
+the device may be fitted to crank-pins and shaft-journals of different
+diameters by other adjusting screws. This device is not hard to operate,
+being merely clamped around the crank-shaft in the same manner as the
+lapping tool previously described, and after it has been properly
+adjusted it is turned around by the levers provided for the purpose, the
+continuous rotary motion removing the metal just as a lathe tool would.
+
+
+FITTING CONNECTING RODS
+
+In the marine type rod, which is the form generally used in airplane
+engines, one or two bolts are employed at each side and the cap must be
+removed entirely before the bearing can be taken off of the crank-pin.
+The tightness of the brasses around the crank-pin can never be
+determined solely by the adjustment of the bolts, as while it is
+important that these should be drawn up as tightly as possible, the
+bearing should fit the shaft without undue binding, even if the brasses
+must be scraped to insure a proper fit. As is true of the main bearings,
+the marine form of connecting rod in some engines has a number of liners
+or shims interposed between the top and lower portions of the rod end,
+and these may be reduced in number when necessary to bring the brasses
+closer together. The general tendency in airplane engines is to
+eliminate shims in either the main or connecting rod bearings, and when
+wear is noticed the boxes or liners are removed and new ones supplied.
+The brasses are held in the connecting rod and cap by brass rivets and
+are generally attached in the main bearing by small brass machine
+screws. The form of box generally favored is a brass sand casting rich
+in copper to secure good heat conductivity which forms a backing for a
+thin layer of white brass, babbitt or similar anti-friction metal.
+
+[Illustration: Fig. 188.--Showing Points to Observe When Fitting
+Connecting Rod Brasses.]
+
+In fitting new brasses there are two conditions to be avoided, these
+being outlined at Fig. 188, B and C. In the case shown at C the light
+edges of the bushings are in contact, but the connecting rod and its cap
+do not meet. When the retaining nuts are tightened the entire strain is
+taken on the comparatively small area of the edges of the bushings which
+are not strong enough to withstand the strains existing and which
+flatten out quickly, permitting the bearing to run loose. In the example
+outlined at B the edges of the brasses do not touch when the connecting
+rod cap is drawn in place. This is not good practice, because the
+brasses soon become loose in their retaining member. In the case
+outlined it is necessary to file off the faces of the rod and cap until
+these meet, and to insure contact of the edges of the brasses as well.
+In event of the brasses coming together before the cap and rod make
+contact, as shown at C, the bearing halves should be reduced at the
+edges until both the caps and brasses meet against each other or the
+surfaces of the liners as shown at A.
+
+
+SPRUNG CAM-SHAFT
+
+If the cam-shaft is sprung or twisted it will alter the valve timing to
+such an extent that the smoothness of operation of the engine will be
+materially affected. If this condition is suspected the cam-shaft may be
+swung on lathe centers and turned to see if it runs out and can be
+straightened in any of the usual form of shaft-straightening machines.
+The shaft may be twisted without being sprung. This can only be
+determined by supporting one end of the shaft in an index head and the
+other end on a milling machine center. The cams are then checked to see
+that they are separated by the proper degree of angularity. This process
+is one that requires a thorough knowledge of the valve timing of the
+engine in question, and is best done at the factory where the engine was
+made. The timing gears should also be examined to see if the teeth are
+worn enough so that considerable back lash or lost motion exists between
+them. This is especially important where worm or spiral gears are used.
+A worn timing gear not only produces noise, but it will cause the time
+of opening and closing of the engine valves to vary materially.
+
+
+PRECAUTIONS IN REASSEMBLING PARTS
+
+When all of the essential components of a power plant have been
+carefully looked over and cleaned and all defects eliminated, either by
+adjustment or replacement of worn portions, the motor should be
+reassembled, taking care to have the parts occupy just the same
+relative positions they did before the motor was dismantled. As each
+part is added to the assemblage care should be taken to insure adequate
+lubrication of all new points of bearing by squirting liberal quantities
+of cylinder oil upon them with a hand oil can or syringe provided for
+the purpose. In adjusting the crank-shaft bearings, tighten them one at
+a time and revolve the shafts each time one of the bearing caps is set
+up to insure that the newly adjusted bearing does not have undue
+friction. All retaining keys and pins must be positively placed and it
+is good practice to cover such a part with lubricant before replacing it
+because it will not only drive in easier, but the part may be removed
+more easily if necessary at some future time. If not oiled, rust
+collects around it.
+
+When a piece is held by more than one bolt or screw, especially if it is
+a casting of brittle material such as cast iron or aluminum, the
+fastening bolts should be tightened uniformly. If one bolt is tightened
+more than the rest it is liable to spring the casting enough to break
+it. Spring washers, check nuts, split pins or other locking means should
+always be provided, especially on parts which are in motion or subjected
+to heavy loads.
+
+Before placing the cylinder over the piston it is imperative that the
+slots in the piston rings are spaced equidistant and that the piston is
+copiously oiled before the cylinder is slipped over it. When
+reassembling the inlet and exhaust manifolds it is well to use only
+perfect packings or gaskets and to avoid the use of those that seem to
+have hardened up or flattened out too much in service. If it is
+necessary to use new gaskets it is imperative to employ these at all
+joints on a manifold, because if old and new gaskets are used together
+the new ones are apt to keep the manifold from bedding properly upon the
+used ones. It is well to coat the threads of all bolts and screws
+subjected to heat, such as cylinder head and exhaust manifold retaining
+bolts, with a mixture of graphite and oil. Those that enter the water
+jacket should be covered with white or red lead or pipe thread
+compound. Gaskets will hold better if coated with shellac before the
+manifold or other parts are placed over them. The shellac fills any
+irregularities in the joint and assists materially in preventing leakage
+after the joint is made up and the coating has a chance to set.
+
+Before assembling on the shaft, it is necessary to fit the bearings by
+scraping, the same instructions given for restoring the contour of the
+main bearings applying just as well in this case. It is apparent that if
+the crank-pins are not round no amount of scraping will insure a true
+bearing. A point to observe is to make sure that the heads of the bolts
+are imbedded solidly in their proper position, and that they are not
+raised by any burrs or particles of dirt under the head which will
+flatten out after the engine has been run for a time and allow the bolts
+to slack off. Similarly, care should be taken that there is no foreign
+matter under the brasses and the box in which they seat. To guard
+against this the bolts should be struck with a hammer several times
+after they are tightened up, and the connecting rod can be hit sharply
+several times under the cap with a wooden mallet or lead hammer. It is
+important to pin the brasses in place to prevent movement, as
+lubrication may be interfered with if the bushing turns round and breaks
+the correct register between the oil hole in the cap and brasses.
+
+Care should be taken in screwing on the retaining nuts to insure that
+they will remain in place and not slack off. Spring washers should not
+be used on either connecting rod ends or main bearing nuts, because
+these sometimes snap in two pieces and leave the nut slack. The best
+method of locking is to use well-fitting split pins and castellated
+nuts.
+
+
+TESTING BEARING PARALLELISM
+
+It is not possible to give other than general directions regarding the
+proper degree of tightening for a connecting rod bearing, but as a guide
+to correct adjustment it may be said that if the connecting rod cap is
+tightened sufficiently so the connecting rod will just about fall over
+from a vertical position due to the piston weight when the bolts are
+fully tightened up, the adjustment will be nearly correct. As previously
+stated, babbitt or white metal bearings can be set up more tightly than
+bronze, as the metal is softer and any high spots will soon be leveled
+down with the running of the engine. It is important that care be taken
+to preserve parallelism of the wrist-pins and crank-shafts while
+scraping in bearings. This can be determined in two ways. That shown at
+Fig. 189, A, is used when the parts are not in the engine assembly and
+when the connecting rod bearing is being fitted to a mandrel or arbor
+the same size as the crank-pin. The arbor, which is finished very smooth
+and of uniform diameter, is placed in two V blocks, which in turn are
+supported by a level surface plate. An adjustable height gauge may be
+tried, first at one side of the wrist-pin which is placed at the upper
+end of the connecting rod, then at the other, and any variation will be
+easily determined by the degree of tilting of the rod. This test may be
+made with the wrist-pin alone, or if the piston is in place, a straight
+edge or spirit level may be employed. The spirit level will readily show
+any inclination while the straight edge is used in connection with the
+height gauge as indicated. Of course, the surface plate must be
+absolutely level when tests are made.
+
+When the connecting rods are being fitted with the crank-shaft in place
+in crank-case, and that member secured in the frame, a steel square may
+be used as it is reasonable to assume that the wrist-pin, and
+consequently the piston it carries, should observe a true relation with
+the top of the engine base. If the piston side is at right angles with
+the top of the engine base it is reasonable to assume that the wrist-pin
+and crank-pin are parallel. If the piston is canted to one side or the
+other, it will indicate that the brasses have been scraped tapering,
+which would mean considerable heating and undue friction if the piston
+is installed in the cylinder on account of the pressure against one
+portion of the cylinder wall. If the degree of canting is not too great,
+the connecting rods may be sprung very slightly to straighten up the
+piston, but this is a makeshift that is not advised. The height gauge
+method shown above may be used instead of the steel square, if desired,
+because the top of the crank-case is planed or milled true and should be
+parallel with the center line of the crank-shaft.
+
+[Illustration: Fig. 189.--Methods of Testing to Insure Parallelism of
+Bearings After Fitting.]
+
+
+CAM-SHAFTS AND TIMING GEARS
+
+Knocking sounds are also evident if the cam-shaft is loose in its
+bearings, and also if the cams or timing gears are loose on the shaft.
+The cam-shaft is usually supported by solid bearings of the removable
+bushing type, having no compensation for depreciation. If these bearings
+wear the only remedy is replacement with new ones. In the older makes of
+cars it was general practice to machine the cams separately and to
+secure these to the cam-shaft by means of taper pins or keys. These
+members sometimes loosened and caused noise. In the event of the cams
+being loose, care should be taken to use new keys or taper pins, as the
+case may be. If the fastening used was a pin, the hole through the
+cam-shaft will invariably be slightly oval from wear. In order to insure
+a tight job, the holes in cam and shaft must be reamed with the next
+larger size of standard taper reamer and a larger pin driven in. Another
+point to watch is the method of retaining the cam-shaft gear in place.
+On some engines the gear is fastened to a flange on the cam-shaft by
+retaining screws. These are not apt to become loose, but where reliance
+is placed on a key the cam-shaft gear may often be loose on its
+supporting member. The only remedy is to enlarge the key slot in both
+gear and shaft and to fit a larger retaining key.
+
+
+
+
+CHAPTER XII
+
+    Aviation Engine Types--Division in Classes--Anzani Engines--
+    Canton and Unné Engine--Construction of Gnome Engines--
+    "Monosoupape" Gnome--German "Gnome" Type--Le Rhone Engine--
+    Renault Air-Cooled Engine--Simplex Model "A" Hispano-Suiza--
+    Curtiss Aviation Motors--Thomas-Morse Model 88 Engine--
+    Duesenberg Engine--Aeromarine Six-Cylinder--Wisconsin Aviation
+    Engines--Hall-Scott Engines--Mercedes Motor--Benz Motor--
+    Austro-Daimler--Sunbeam-Coatalen.
+
+
+AVIATION ENGINE TYPES
+
+Inasmuch as numerous forms of airplane engines have been devised, it
+would require a volume of considerable size to describe even the most
+important developments of recent years. As considerable explanatory
+matter has been given in preceding chapters and the principles involved
+in internal combustion engine operation considered in detail, a
+relatively brief review of the features of some of the most successful
+airplane motors should suffice to give the reader a complete enough
+understanding of the art so all types of engines can be readily
+recognized and the advantages and disadvantages of each type understood,
+as well as defining the constructional features enough so the methods of
+locating and repairing the common engine and auxiliary system troubles
+will be fully grasped.
+
+Aviation engines can be divided into three main classes. One of the
+earliest attempts to devise distinctive power plant designs for aircraft
+involved the construction of engines utilizing a radial arrangement of
+the cylinders or a star-wise disposition. Among the engines of this
+class may be mentioned the Anzani, R. E. P. and the Salmson or Canton
+and Unné forms. The two former are air-cooled, the latter design is
+water-cooled. Engines of this type have been built in cylinder numbers
+ranging from three to twenty. While the simple forms were popular in the
+early days of aviation engine development, they have been succeeded by
+the more conventional arrangements which now form the largest class. The
+reason for the adoption of a star-wise arrangement of cylinders has been
+previously considered. Smoothness of running can only be obtained by
+using a considerable number of cylinders. The fundamental reason for the
+adoption of the star-wise disposition is that a better distribution of
+stress is obtained by having all of the pistons acting on the same
+crank-pin so that the crank-throw and pin are continuously under maximum
+stress. Some difficulty has been experienced in lubricating the lower
+cylinders in some forms of six cylinder, rotary crank, radial engines
+but these have been largely overcome so they are not as serious in
+practice as a theoretical consideration would indicate.
+
+Another class of engines developed to meet aviation requirements is a
+complete departure from the preceding class, though when the engines are
+at rest, it is difficult to differentiate between them. This class
+includes engines having a star-wise disposition of the cylinders but the
+cylinders themselves and the crank-case rotate and the crank-shaft
+remains stationary. The important rotary engines are the Gnome, the Le
+Rhone and the Clerget. By far the most important classification is that
+including engines which retain the approved design of the types of power
+plants that have been so widely utilized in automobiles and which have
+but slight modifications to increase reliability and mechanical strength
+and produce a reduction in weight. This class includes the vertical
+engines such as the Duesenberg and Hall-Scott four-cylinder; the
+Wisconsin, Aeromarine, Mercedes, Benz, and Hall-Scott six-cylinder
+vertical engines and the numerous eight- and twelve-cylinder Vee designs
+such as the Curtiss, Renault, Thomas-Morse, Sturtevant, Sunbeam, and
+others.
+
+
+ANZANI ENGINES
+
+The attention of the mechanical world was first directed to the great
+possibilities of mechanical flight when Bleriot crossed the English
+Channel in July, 1909, in a monoplane of his own design and
+construction, having the power furnished by a small three-cylinder
+air-cooled engine rated at about 24 horse-power and having cylinders
+4.13 inches bore and 5.12 inches stroke, stated to develop the power at
+about 1600 R.P.M. and weighing 145 pounds. The arrangement of this early
+Anzani engine is shown at Fig. 190, and it will be apparent that in the
+main, the lines worked out in motorcycle practice were followed to a
+large extent. The crank-case was of the usual vertically divided
+pattern, the cylinders and heads being cast in one piece and held to the
+crank-case by stud bolts passing through substantial flanges at the
+cylinder base. In order to utilize but a single crank-pin for the three
+cylinders it was necessary to use two forked rods and one rod of the
+conventional type. The arrangement shown at Fig. 190, called for the use
+of counter-balanced flywheels which were built up in connection with
+shafts and a crank-pin to form what corresponds to the usual crank-shaft
+assembly.
+
+[Illustration: Fig. 190.--Views Outlining Construction of Three-Cylinder
+Anzani Aviation Motor.]
+
+The inlet valves were of the automatic type so that a very simple valve
+mechanism consisting only of the exhaust valve push rods was provided.
+One of the difficulties of this arrangement of cylinders was that the
+impulses are not evenly spaced. For instance, in the forms where the
+cylinders were placed 60 degrees apart the space between the firing of
+the first cylinder and that next in order was 120 degrees crank-shaft
+rotation, after which there was an interval of 300 degrees before the
+last cylinder to fire delivered its power stroke. In order to increase
+the power given by the simple three-cylinder air-cooled engine a
+six-cylinder water-cooled type, as shown at Figs. 191 and 192, was
+devised. This was practically the same in action as the three-cylinder
+except that a double throw crank-shaft was used and while the
+explosions were not evenly spaced the number of explosions obtained
+resulted in fairly uniform application of power.
+
+[Illustration: Fig. 190a.--Illustrations Depicting Wrong and Right
+Methods of "Swinging the Stick" to Start Airplane Engine. At Top, Poor
+Position to Get Full Throw and Get Out of the Way. Below, Correct
+Position to Get Quick Turn Over of Crank-Shaft and Spring Away from
+Propeller.]
+
+[Illustration: Fig. 191.--The Anzani Six-Cylinder Water-Cooled Aviation
+Engine.]
+
+[Illustration: Fig. 192.--Sectional View of Anzani Six-Cylinder
+Water-Cooled Aviation Engine.]
+
+The latest design of three-cylinder Anzani engine, which is used to some
+extent for school machines, is shown at Fig. 193. In this, the
+three-cylinders are symmetrically arranged about the crank-case or 120
+degrees apart. The balance is greatly improved by this arrangement and
+the power strokes occur at equal intervals of 240 degrees of crank-shaft
+rotation. This method of construction is known as the Y design. By
+grouping two of these engines together, as outlined at Fig. 194, which
+gives an internal view, and at Fig. 195, which shows the sectional view,
+and using the ordinary form of double throw crank-shaft with crank-pins
+separated by 180 degrees, a six-cylinder radial engine is produced which
+runs very quietly and furnishes a steady output of power. The
+peculiarity of the construction of this engine is in the method of
+grouping the connecting rod about the common crank-pin without using
+forked rods or the "Mother rod" system employed in the Gnome engines. In
+the Anzani the method followed is to provide each connecting rod big end
+with a shoe which consists of a portion of a hollow cylinder held
+against the crank-pin by split clamping rings. The dimensions of these
+shoes are so proportioned that the two adjacent connecting rods of a
+group of three will not come into contact even when the connecting rods
+are at the minimum relative angle. The three shoes of each group rest
+upon a bronze sleeve which is in halves and which surrounds the
+crank-pin and rotates relatively to it once in each crank-shaft
+revolution. The collars, which are of tough bronze, resist the inertia
+forces while the direct pressure of the explosions is transmitted
+directly to the crank-pin bushing by the shoes at the big end of the
+connecting rod. The same method of construction, modified to some
+extent, is used in the Le Rhone rotary cylinder engine.
+
+[Illustration: Fig. 193.--Three-Cylinder Anzani Air-Cooled Y-Form
+Engine.]
+
+[Illustration: Fig. 194.--Anzani Fixed Crank-Case Engine of the
+Six-Cylinder Form Utilizes Air Cooling Successfully.]
+
+Both cylinders and pistons of the Anzani engines are of cast iron, the
+cylinders being provided with a liberal number of cooling flanges which
+are cast integrally. A series of auxiliary exhaust ports is drilled near
+the base of each cylinder so that a portion of the exhaust gases will
+flow out of the cylinder when the piston reaches the end of its power
+stroke. This reduces the temperature of the gases passing around the
+exhaust valves and prevents warping of these members. Another
+distinctive feature of this engine design is the method of attaching the
+Zenith carburetor to an annular chamber surrounding the rear portion of
+the crank-case from which the intake pipes leading to the intake valves
+radiate. The magneto is the usual six-cylinder form having the armature
+geared to revolve at one and one-half times crank-shaft speed.
+
+[Illustration: Fig. 195.--Sectional View Showing Internal Parts of
+Six-Cylinder Anzani Engine, with Starwise Disposition of Cylinders.]
+
+[Illustration: Fig. 196.--The Anzani Ten-Cylinder Aviation Engine at
+the Left, and the Twenty-Cylinder Fixed Type at the Right.]
+
+The Anzani aviation engines are also made in ten- and twenty-cylinder
+forms as shown at Fig. 196. It will be apparent that in the
+ten-cylinder form explosions will occur every 72 degrees of crank-shaft
+rotation, while in the twenty-cylinder, 200 horse-power engine at any
+instant five of the cylinders are always working and explosions are
+occurring every 36 degrees of crank-shaft rotation. On the
+twenty-cylinder engine, two carburetors are used and two magnetos,
+which are driven at two and one-half times crank-shaft speed. The
+general cylinder and valve construction is practically the same, as in
+the simpler engines.
+
+[Illustration: Fig. 197.--Application of R. E. P. Five-Cylinder
+Fan-Shape Air-Cooled Motor to Early Monoplane.]
+
+
+CANTON AND UNNÉ ENGINE
+
+This engine, which has been devised specially for aviation service, is
+generally known as the "Salmson" and is manufactured in both France and
+Great Britain. It is a nine-cylinder water-cooled radial engine, the
+nine cylinders being symmetrically disposed around the crank-shaft while
+the nine connecting rods all operate on a common crank-pin in somewhat
+the same manner as the rods in the Gnome motor. The crank-shaft of the
+Salmson engine is not a fixed one and inasmuch as the cylinders do not
+rotate about the crank-shaft it is necessary for that member to revolve
+as in the conventional engine. The stout hollow steel crank-shaft is in
+two pieces and has a single throw. The crank-shaft is built up somewhat
+the same as that of the Gnome engine. Ball bearings are used throughout
+this engine as will be evident by inspecting the sectional view given at
+Fig. 199. The nine steel connecting rods are machined all over and are
+fitted at each end with bronze bushings, the distance between the
+bearing centers being about 3.25 times crank length. The method of
+connecting up the rods to the crank-pin is one of the characteristic
+features of this design. No "mother" rod as supplied in the Gnome engine
+is used in this type inasmuch as the steel cage or connecting rod
+carrier is fitted with symmetrically disposed big end retaining pins.
+Inasmuch as the carrier is mounted on ball bearings some means must be
+provided of regulating the motion of the carrier as if no means were
+provided the resulting motion of the pistons would be irregular.
+
+[Illustration: Fig. 198.--The Canton and Unné Nine-Cylinder Water-Cooled
+Radial Engine.]
+
+The method by which the piston strokes are made to occur at precise
+intervals involves a somewhat lengthy and detailed technical
+explanation. It is sufficient to say that an epicyclic train of gears,
+one of which is rigidly attached to the crank-case so it cannot rotate
+is used, while other gears make a connection between the fixed gear and
+with another gear which is exactly the same size as the fixed gear
+attached to the crank-case and which is formed integrally with the
+connecting rod carrier. The action of the gearing is such that the cage
+carrying the big end retaining pins does not rotate independently of
+the crank-shaft, though, of course, the crank-shaft or rather crank-pin
+bearings must turn inside of the big end carrier cage.
+
+[Illustration: Fig. 199.--Sectional View Showing Construction of Canton
+and Unné Water-Cooled Radial Cylinder Engine.]
+
+Cylinders of this engine are of nickel steel machined all over and carry
+water-jackets of spun copper which are attached to the cylinders by
+brazing. The water jackets are corrugated to permit the cylinder to
+expand freely. The ignition is similar to that of the fixed crank
+rotating cylinder engine. An ordinary magneto of the two spark type
+driven at 1-3/4 times crank-shaft speed is sufficient to ignite the
+seven-cylinder form, while in the nine-cylinder engines the ignition
+magneto is of the "shield" type giving four sparks per revolution. The
+magneto is driven at 1-1/9 times crank-shaft speed. Nickel steel valves
+are used and are carried in castings or cages which screw into bosses in
+the cylinder head. Each valve is cam operated through a tappet, push rod
+and rocker arm, seven cams being used on a seven-cylinder engine and
+nine cams on the nine-cylinder. One cam serves to open both valves as in
+its rotation it lifts the tappets in succession and so operates the
+exhaust and inlet valves respectively. This method of operation involves
+the same period of intake and exhaust. In normal engine practice the
+inlet valve opens 12 degrees late and closes 20 degrees late. The
+exhaust opens 45 degrees early and closes 6 degrees late. This means
+about 188 degrees in the case of inlet valve and 231 degrees crank-shaft
+travel for exhaust valves. In the Salmson engine, the exhaust closes and
+the inlet opens at the outer dead center and the exhaust opens and the
+inlet closes at about the inner dead center. This engine is also made in
+a fourteen-cylinder 200 B. H. P. design which is composed of two groups
+of seven-cylinders, and it has been made in an eighteen-cylinder design
+of 600 horse-power. The nine-cylinder 130 horse-power has a cylinder
+bore of 4.73 inches and a stroke of 5.52 inches. Its normal speed of
+rotation is 1250 R. P. M. Owing to the radial arrangement of the
+cylinders, the weight is but 4-1/4 pounds per B. H. P.
+
+
+CONSTRUCTION OF EARLY GNOME MOTOR
+
+It cannot be denied that for a time one of the most widely used of
+aeroplane motors was the seven-cylinder revolving air-cooled Gnome, made
+in France. For a total weight of 167 pounds this motor developed 45 to
+47 horse-power at 1,000 revolutions, being equal to 3.35 pounds per
+horse-power, and has proved its reliability by securing many
+long-distance and endurance records. The same engineers have produced
+a nine-cylinder and by combining two single engines a fourteen-cylinder
+revolving Gnome, having a nominal rating of 100 horse-power, with which
+world's speed records were broken. A still more powerful engine has been
+made with eighteen-cylinders. The nine-cylinder "monosoupape" delivers
+100 horse-power at 1200 R. P. M., the engine of double that number of
+cylinders is rated at about 180 horse-power.
+
+[Illustration: Fig. 200.--Sectional View Outlining Construction of Early
+Type Gnome Valve-in-Piston Type Motor.]
+
+Except in the number of cylinders and a few mechanical details the
+fourteen-cylinder motor is identical with the seven-cylinder one; fully
+three-quarters of the parts used by the assemblers would do just as well
+for one motor as for the other. Owing to the greater power demands of
+the modern airplane the smaller sizes of Gnome engines are not used as
+much as they were except for school machines. There is very little in
+this motor that is common to the standard type of vertical motorcar
+engine. The cylinders are mounted radially round a circular crank-case;
+the crank-shaft is fixed, and the entire mass of cylinders and
+crank-case revolves around it as outlined at Fig. 200. The explosive
+mixture and the lubricating oil are admitted through the fixed hollow
+crank-shaft, passed into the explosion chamber through an automatic
+intake valve in the piston head in the early pattern, and the spent
+gases exhausted through a mechanically operated valve in the cylinder
+head. The course of the gases is practically a radial one. A peculiarity
+of the construction of the motor is that nickel steel is used
+throughout. Aluminum is employed for the two oil pump housings; the
+single compression ring known as the "obdurator" for each piston is made
+of brass; there are three or four brass bushes; gun metal is employed
+for certain pins--the rest is machined out of chrome nickel steel. The
+crank-case is practically a steel hoop, the depth depending on whether
+it has to receive seven-or fourteen-cylinders; it has seven or fourteen
+holes bored as illustrated on its circumference. When fourteen or
+eighteen cylinders are used the holes are bored in two distinct planes,
+and offset in relation one to the other.
+
+The cylinders of the small engine which have a bore of 4-3/10 inches and
+a stroke of 4-7/10 inches, are machined out of the solid bar of steel
+until the thickness of the walls is only 1.5 millimeters--.05905 inch,
+or practically 1/16 inch. Each one has twenty-two fins which gradually
+taper down as the region of greatest pressure is departed from. In
+addition to carrying away heat, the fins assist in strengthening the
+walls of the cylinder. The barrel of the cylinder is slipped into the
+hole bored for it on the circumference of the crank-case and secured by
+a locking member in the nature of a stout compression ring, sprung onto
+a groove on the base of the cylinder within the crank chamber. On each
+lateral face of the crank chamber are seven holes, drilled right through
+the chamber parallel with the crank-shaft. Each one of these holes
+receives a stout locking-pin of such a diameter that it presses against
+the split rings of two adjacent cylinders; in addition each cylinder is
+fitted with a key-way. This construction is not always followed, some of
+the early Gnome engines using the same system of cylinder retention as
+used on the latest "monosoupape" pattern.
+
+The exhaust valve is mounted in the cylinder head, Fig. 201, its seating
+being screwed in by means of a special box spanner. On the
+fourteen-cylinder model the valve is operated directly by an overhead
+rocker arm with a gun metal rocker at its extremity coming in contact
+with the extremity of the valve stem. As in standard motor car practice,
+the valve is opened under the lift of the vertical push rod, actuated by
+the cam. The distinctive feature is the use of a four-blade leaf spring
+with a forked end encircling the valve stems and pressing against a
+collar on its extremity. On the seven-cylinder model the movement is
+reversed, the valve being opened on the downward pull of the push rod,
+this lifting the outer extremity of the main rocker arm, which tips a
+secondary and smaller rocker arm in direct contact with the extremity
+of the valve stem. The springs are the same in each case. The two types
+are compared at A and B, Fig. 202.
+
+[Illustration: Fig. 201.--Sectional View of Early Type Gnome Cylinder
+and Piston Showing Construction and Application of Inlet and Exhaust
+Valves.]
+
+The pistons, like the cylinders, are machined out of the solid bar of
+nickel steel, and have a portion of their wall cut away, so that the two
+adjacent ones will not come together at the extremity of their stroke.
+The head of the piston is slightly reduced in diameter and is provided
+with a groove into which is fitted a very light L-section brass split
+ring; back of this ring and carried within the groove is sprung a light
+steel compression ring, serving to keep the brass ring in expansion. As
+already mentioned, the intake valves are automatic, and are mounted in
+the head of the piston as outlined at Fig. 202, C. The valve seating is
+in halves, the lower portion being made to receive the wrist-pin and
+connecting rod, and the upper portion, carrying the valve, being screwed
+into it. The spring is composed of four flat blades, with the hollowed
+stem of the automatic valve passing through their center and their two
+extremities attached to small levers calculated to give balance against
+centrifugal force. The springs are naturally within the piston, and are
+lubricated by splash from the crank chamber. They are of a delicate
+construction, for it is necessary that they shall be accurately balanced
+so as to have no tendency to fly open under the action of centrifugal
+force. The intake valve is withdrawn by the use of special tools through
+the cylinder head, the exhaust valve being first dismounted.
+
+[Illustration: Fig. 202.--Details of Old Style Gnome Motor Inlet and
+Exhaust Valve Construction and Operation.]
+
+The fourteen-cylinder motor shown at Fig. 203, has a two-throw
+crank-shaft with the throws placed at 180 degrees, each one receiving
+seven connecting rods. The parts are the same as for the seven-cylinder
+motor, the larger one consisting of two groups placed side by side. For
+each group of seven-cylinders there is one main connecting rod, together
+with six auxiliary rods. The main connecting rod, which, like the
+others, is of H section, has machined with it two L-section rings bored
+with six holes--51-1/2 degrees apart to take the six other connecting
+rods. The cage of the main connecting rod carries two ball races, one on
+either side, fitting onto the crank-pin and receiving the thrust of the
+seven connecting rods. The auxiliary connecting rods are secured in
+position in each case by a hollow steel pin passing through the two
+rings. It is evident that there is a slightly greater angularity for the
+six shorter rods, known as auxiliary connecting rods, than for the
+longer main rods; this does not appear to have any influence on the
+running of the motor.
+
+[Illustration: Fig. 203.--The Gnome Fourteen-Cylinder 100 Horse-Power
+Aviation Engine.]
+
+Coming to the manner in which the earliest design exhaust valves are
+operated on the old style motor, this at first sight appears to be one
+of the most complicated parts of the motor, probably because it is one
+in which standard practice is most widely departed from. Within the
+cylindrical casing bolted to the rear face of the crank-case are seven,
+thin flat-faced steel rings, forming female cams. Across a diameter of
+each ring is a pair of projecting rods fitting in brass guides and
+having their extremities terminating in a knuckle eye receiving the
+adjustable push rods operating the overhead rocker arms of the exhaust
+valve. The guides are not all in the same plane, the difference being
+equal to the thickness of the steel rings, the total thickness being
+practically 2 inches. Within the female cams is a group of seven male
+cams of the same total thickness as the former and rotating within them.
+As the boss of the male cam comes into contact with the flattened
+portion of the ring forming the female cam, the arm is pushed outward
+and the exhaust valve opened through the medium of the push-rod and
+overhead rocker. This construction was afterwards changed to seven male
+cams and simple valve operating plunger and roller cam followers as
+shown at Fig. 204.
+
+On the face of the crank-case of the fourteen-cylinder motor opposite to
+the valve mechanism is a bolted-on end plate, carrying a pinion for
+driving the two magnetos and the two oil pumps, and having bolted to it
+the distributor for the high-tension current. Each group of
+seven-cylinders has its own magneto and lubricating pump. The two
+magnetos and the two pumps are mounted on the fixed platform carrying
+the stationary crank-shaft, being driven by the pinion on the revolving
+crank chamber. The magnetos are geared up in the proportion of 4 to 7.
+Mounted on the end plate back of the driving pinion are the two
+high-tension distributor plates, each one with seven brass segments let
+into it and connection made to the plugs by means of plain brass wire.
+The wire passes through a hole in the plug and is then wrapped round
+itself, giving a loose connection.
+
+[Illustration: Fig. 204.--Cam and Cam-Gear Case of the Gnome
+Seven-Cylinder Revolving Engine.]
+
+[Illustration: Fig. 205.--Diagrams Showing Why An Odd Number of
+Cylinders is Best for Rotary Cylinder Motors.]
+
+A good many people doubtless wonder why rotary engines are usually
+provided with an odd number of cylinders in preference to an even
+number. It is a matter of even torque, as can easily be understood from
+the accompanying diagram. Fig. 205, A, represents a six-cylinder rotary
+engine, the radial lines indicating the cylinders. It is possible to
+fire the charges in two ways, firstly, in rotation, 1, 2, 3, 4, 5, 6,
+thus having six impulses in one revolution and none in the next; or
+alternately, 1, 3, 5, 2, 4, 6, in which case the engine will have turned
+through an equal number of degrees between impulses 1 and 3, and 3 and
+5, but a greater number between 5 and 2, even again between 2 and 4, 4
+and 6, and a less number between 6 and 1, as will be clearly seen on
+reference to the diagram. Turning to Fig. 205, B, which represents a
+seven-cylinder engine. If the cylinders fire alternately it is obvious
+that the engine turns through an equal number of degrees between each
+impulse, thus, 1, 3, 5, 7, 2, 4, 6, 1, 3, etc. Thus supposing the engine
+to be revolving, the explosion takes place as each alternate cylinder
+passes, for instance, the point 1 on the diagram, and the ignition is
+actually operated in this way by a single contact.
+
+[Illustration: Fig. 206.--Simple Carburetor Used On Early Gnome Engines
+Attached to Fixed Crank-Shaft End.]
+
+The crank-shaft of the Gnome, as already explained, is fixed and hollow.
+For the seven- and nine-cylinder motors it has a single throw, and for
+the fourteen- and eighteen-cylinder models has two throws at 180
+degrees. It is of the built-up type, this being necessary on account of
+the distinctive mounting of the connecting rods. The carburetor shown at
+Fig. 206 is mounted at one end of the stationary crank-shaft, and the
+mixture is drawn in through a valve in the piston as already explained.
+There is neither float chamber nor jet. In many of the tests made at the
+factory it is said the motor will run with the extremity of the gasoline
+pipe pushed into the hollow crank-shaft, speed being regulated entirely
+by increasing or decreasing the flow through the shut-off valve in the
+base of the tank. Even under these conditions the motor has been
+throttled down to run at 350 revolutions without misfiring. Its normal
+speed is 1,000 to 1,200 revolutions a minute. Castor oil is used for
+lubricating the engine, the oil being injected into the hollow
+crank-shaft through slight-feed fittings by a mechanically operated pump
+which is clearly shown in sectional diagrams at Fig. 207.
+
+[Illustration: Fig. 207.--Sectional Views of the Gnome Oil Pump.]
+
+The Gnome is a considerable consumer of lubricant, the makers' estimate
+being 7 pints an hour for the 100 horse-power motor; but in practice
+this is largely exceeded. The gasoline consumption is given as 300 to
+350 grammes per horse-power. The total weight of the fourteen-cylinder
+motor is 220 pounds without fuel or lubricating oil. Its full power is
+developed at 1,200 revolutions, and at this speed about 9 horse-power is
+lost in overcoming air resistance to cylinder rotation.
+
+[Illustration: Fig. 208.--Simplified Diagram Showing Gnome Motor Magneto
+Ignition System.]
+
+While the Gnome engine has many advantages, on the other hand, the head
+resistance offered by a motor of this type is considerable; there is a
+large waste of lubricating oil due to the centrifugal force which tends
+to throw the oil away from the cylinders; the gyroscopic effect of the
+rotary motor is detrimental to the best working of the aeroplane, and
+moreover it requires about seven per cent. of the total power developed
+by the motor to drive the revolving cylinders around the shaft. Of
+necessity, the compression of this type of motor is rather low, and an
+additional disadvantage manifests itself in the fact that there is as
+yet no satisfactory way of muffling the rotary type of motor.
+
+
+GNOME "MONOSOUPAPE" TYPE
+
+The latest type of Gnome engine is known as the "monosoupape" type
+because but one valve is used in the cylinder head, the inlet valve in
+the piston being dispensed with on account of the trouble caused by that
+member on earlier engines. The construction of this latest type follows
+the lines established in the earlier designs to some extent and it
+differs only in the method of charging. The very rich mixture of gas and
+air is forced into the crank-case through the jet inside the
+crank-shaft, and enters the cylinder when the piston is at its lowest
+position, through the half-round openings in the guiding flange and the
+small holes or ports machined in the cylinder and clearly shown at Fig.
+210. The returning piston covers the port, and the gas is compressed and
+fired in the usual way. The exhaust is through a large single valve in
+the cylinder head, which gives rise to the name "monosoupape," or
+single-valve motor, and this valve also remains open a portion of the
+intake stroke to admit air into the cylinder and dilute the rich gas
+forced in from the crank-case interior. Aviators who have used the early
+form of Gnome say that the inlet valve in the piston type was prone to
+catch on fire if any valve defect materialized, but the "monosoupape"
+pattern is said to be nearly free of this danger. The bore of the 100
+horse-power nine-cylinder engine is 110 mm., the piston stroke 150 mm.
+Extremely careful machine work and fitting is necessary. In many parts,
+tolerances of less than .0004" (four ten thousandths of an inch) are all
+that are allowed. This is about one-sixth the thickness of the average
+human hair, and in other parts the size must be absolutely standard, no
+appreciable variation being allowable. The manufacture of this engine
+establishes new mechanical standards of engine production in this
+country. Much machine work is needed in producing the finished
+components from the bar and forging.
+
+[Illustration: Fig. 209.--The G. V. Gnome "Monosoupape" Nine-Cylinder
+Rotary Engine Mounted on Testing Stand.]
+
+[Illustration: Fig. 210.--Sectional View Showing Construction of General
+Vehicle Co. "Monosoupape" Gnome Engine.]
+
+The cylinders, for example, are machined from 6 inch solid steel bars,
+which are sawed into blanks 11 inches in length and weighing about 97
+pounds. The first operation is to drill a 2-1/16 inch hole through the
+center of the block. A heavy-duty drilling machine performs this work,
+then the block goes to the lathe for further operations. Fig. 211 shows
+six stages of the progress of a cylinder, a few of the intermediate
+steps being omitted. These give, however, a good idea of the work done.
+The turning of the gills, or cooling flanges, is a difficult
+proposition, owing to the depth of the cut and the thin metal that forms
+the gills. This operation requires the utmost care of tools and the use
+of a good lubricant to prevent the metal from tearing as the tools
+approach their full depth. These gills are only 0.6 mm., or 0.0237 in.,
+thick at the top, tapering to a thickness of 1.4 mm. (0.0553 in.) at the
+base, and are 16 mm. (0.632 in.) deep. When the machine work is
+completed the cylinder weighs but 5-1/2 pounds.
+
+[Illustration: Fig. 211.--How a Gnome Cylinder is Reduced from Solid
+Chunk of Steel Weighing 97 Pounds to Finished Cylinder Weighing 5-1/2
+Pounds.]
+
+
+GNOME FUEL SYSTEM, IGNITION AND LUBRICATION
+
+The following description of the fuel supply, ignition and oiling of the
+"monosoupape," or single valve Gnome, is taken from "The Automobile."
+
+Gasoline is fed to the engine by means of air pressure at 5 pounds per
+sq. in., which is produced by the air pump on the engine clearly shown
+at Fig. 210. A pressure gauge convenient to the operator indicates this
+pressure, and a valve enables the operator to control it. No carburetor
+is used. The gasoline flows from the tank through a shut-off valve near
+the operator and through a tube leading through the hollow crank-shaft
+to a spray nozzle located in the crank-case. There is no throttle valve,
+and as each cylinder always receives the same amount of air as long as
+the atmospheric pressure is the same, the output cannot be varied by
+reducing the fuel supply, except within narrow limits. A fuel capacity
+of 65 gallons is provided. The fuel consumption is at the rate of 12 U.
+S. gallons per hour.
+
+The high-tension magnetos, with double cam or two break per revolution
+interrupter, is located on the thrust plate in an inverted position, and
+is driven at such a speed as to produce nine sparks for every two
+revolutions; that is, at 2-1/4 times engine speed. A Splitdorf magneto
+is fitted. There is no distributor on the magneto. The high-tension
+collector brush of the magneto is connected to a distributor brush
+holder carried in the bearer plate of the engine. The brush in this
+brush holder is pressed against a distributor ring of insulating
+material molded in position in the web of a gear wheel keyed to the
+thrust plate, which gear serves also for starting the engine by hand.
+Molded in this ring of insulating material are nine brass contact
+sectors, connecting with contact screws at the back side of the gear,
+from which bare wires connect to the spark-plugs. The distributor
+revolves at engine speed, instead of at half engine speed as on ordinary
+engines, and the distributor brush is brought into electrical connection
+with each spark-plug every time the piston in the cylinder in which this
+spark-plug is located approaches the outer dead center. However, on the
+exhaust stroke no spark is being generated in the magneto, hence none is
+produced at the spark-plug.
+
+[Illustration: Fig. 212.--The Gnome Engine Cam-Gear Case, a Fine Example
+of Accurate Machine Work.]
+
+Ordinarily the engine is started by turning on the propeller, but for
+emergency purposes as in seaplanes or for a quick "get away" if landing
+inadvertently in enemy territory, a hand starting crank is provided.
+This is supported in bearings secured to the pressed steel carriers of
+the engine and is provided with a universal joint between the two
+supports so as to prevent binding of the crank in the bearings due to
+possible distortion of the supports. The gear on this starting crank and
+the one on the thrust plate with which it meshes are cut with helical
+teeth of such hand that the starting pinion is thrown out of mesh as
+soon as the engine picks up its cycle. A coiled spring surrounds part of
+the shaft of the starting crank and holds it out of gear when not in
+use.
+
+[Illustration: Fig. 213.--G. V. Gnome "Monosoupape," with Cam-Case Cover
+Removed to Show Cams and Valve-Operating Plungers with Roller Cam
+Followers.]
+
+Lubricating oil is carried in a tank of 25 gallon capacity, and if this
+tank has to be placed in a low position it is connected with the
+air-pressure line, so that the suction of the oil pump is not depended
+upon to get the oil to the pump. From the bottom of the oil tank a pipe
+leads to the pump inlet. There are two outlets from the pump, each
+entering the hollow crank-shaft, and there is a branch from each outlet
+pipe to a circulation indicator convenient to the operator. One of the
+oil leads feeds to the housing in the thrust plate containing the two
+rear ball bearings, and the other lead feeds through the crank-pin to
+the cams, as already explained.
+
+Owing to the effect of centrifugal force and the fact that the oil is
+not used over again, the oil consumption of a revolving cylinder engine
+is considerably higher than that of a stationary cylinder engine. Fuel
+consumption is also somewhat higher, and for this reason the revolving
+cylinder engine is not so well suited for types of airplanes designed
+for long trips, as the increased weight of supplies required for such
+trips, as compared with stationary cylinder type motors, more than
+offsets the high weight efficiency of the engine itself. But for short
+trips, and especially where high speed is required, as in single seated
+scout and battle planes or "avions de chasse," as the French say, the
+revolving cylinder engine has the advantage. The oil consumption of the
+Gnome engine is as high as 2.4 gallon per hour. Castor oil is used for
+lubrication because it is not cut by the gasoline mist present in the
+engine interior as an oil of mineral derivation would be.
+
+
+GERMAN "GNOME" TYPE ENGINE
+
+[Illustration: Fig. 214.--The 50 Horse-Power Rotary Bayerischen Motoren
+Gesellschaft Engine, a German Adaptation of the Early Gnome Design.]
+
+A German adaptation of the Gnome design is shown at Fig. 214. This is
+known as the Bayerischen Motoren Gesellschaft engine and the type shown
+is an early design rated at 50 horse-power. The bore is 110 mm., the
+stroke is 120 mm., and it is designed to run at a speed of 1,200 R. P.
+M. It is somewhat similar in design to the early Gnome "valve-in-piston"
+design except that two valves are carried in the piston top instead of
+one. The valve operating arrangement is different also, as a single four
+point cam is used to operate the seven exhaust valves. It is driven by
+epicyclic gearing, the cam being driven by an internal gear machined
+integrally with it, the cam being turned at 7/8 times the engine speed.
+Another feature is the method of holding the cylinders on the
+crank-case. The cylinder is provided with a flange that registers with a
+corresponding member of the same diameter on the crank-case. A U
+section, split clamping ring is bolted in place as shown, this holding
+both flanges firmly together and keeping the cylinder firmly seated
+against the crank-case flange. The "monosoupape" type has also been
+copied and has received some application in Germany, but the most
+successful German airplanes are powered with six-cylinder vertical
+engines such as the Benz and Mercedes.
+
+
+THE LE RHONE MOTOR
+
+The Le Rhone motor is a radial revolving cylinder engine that has many
+of the principles which are incorporated in the Gnome but which are
+considered to be an improvement by many foreign aviators. Instead of
+having but one valve in the cylinder head, as the latest type
+"monosoupape" Gnome has, the Le Rhone has two valves, one for intake and
+one for exhaust in each cylinder. By an ingenious rocker arm and tappet
+rod arrangement it is possible to operate both valves with a single push
+rod. Inlet pipes communicate with the crank-case at one end and direct
+the fresh gas to the inlet valve cage at the other. Another peculiarity
+in the design is the method of holding the cylinders in place. Instead
+of having a vertically divided crank-case as the Gnome engine has and
+clamping both halves of the case around the cylinders, the crank-case of
+the Le Rhone engine is in the form of a cylinder having nine bosses
+provided with threaded openings into which the cylinders are screwed. A
+thread is provided at the base of each cylinder and when the cylinder
+has been screwed down the proper amount it is prevented from further
+rotation about its own axis by a substantial lock nut which screws down
+against the threaded boss on the crank-case. The external appearance of
+the Le Rhone type motor is clearly shown at Fig. 215, while the general
+features of construction are clearly outlined in the sectional views
+given at Figs. 216 and 217.
+
+[Illustration: Fig. 215--Nine-Cylinder Revolving Le Rhone Type Aviation
+Engine.]
+
+[Illustration: Fig. 216.--Part Sectional Views of Le Rhone Rotary
+Cylinder Engine, Showing Method of Cylinder Retention, Valve Operation
+and Novel Crank Disc Assembly.]
+
+[Illustration: Fig. 217.--Side Sectional View of Le Rhone Aviation
+Engine.]
+
+[Illustration: Fig. 218.--View Showing Le Rhone Valve Action and
+Connecting Rod Big End Arrangement.]
+
+The two main peculiarities of this motor are the method of valve
+actuation by two large cams and the distinctive crank-shaft and
+connecting rod big end construction. The connecting rods are provided
+with "feet" or shoes on the end which fit into grooves lined with
+bearing metal which are machined into crank discs revolving on ball
+bearings and which are held together so that the connecting rod big ends
+are sandwiched between them by clamping screws. This construction is a
+modification of that used on the Anzani six-cylinder radial engine.
+There are three grooves machined in each crank disc and three connecting
+rod big ends run in each pair of grooves. The details of this
+construction can be readily ascertained by reference to explanatory
+diagrams at Figs. 218 and 219, A. Three of the rods which work in the
+groove nearest the crank-pin are provided with short shoes as shown at
+Fig. 219, B. The short shoes are used on the rods employed in cylinders
+number 1, 4, and 7. The set of connecting rods that work in the central
+grooves are provided with medium-length shoes and actuate the pistons in
+cylinders numbers 3, 6, and 9. The three rods that work in the outside
+grooves have still longer shoes and are employed in cylinders numbers 2,
+5, and 8. The peculiar profile of the inlet and exhaust cam plates are
+shown at C, Fig. 219, while the construction of the wrist-pin, wrist-pin
+bushing and piston are clearly outlined at the sectional view at E. The
+method of valve actuation is clearly outlined at Fig. 220, which shows
+an end section through the cam case and also a partial side elevation
+showing one of the valve operating levers which is fulcrumed at a
+central point and which has a roller at one end bearing on one cam while
+the roller or cam follower at the other end bears on the other cam. The
+valve rocker arm actuating rod is, of course, operated by this simple
+lever and is attached to it in such a way that it can be pulled down to
+depress the inlet valve and pushed up to open the exhaust valve.
+
+[Illustration: Fig. 219.--Diagrams Showing Important Components of Le
+Rhone Motor.]
+
+[Illustration: Fig. 220.--How the Cams of the Le Rhone Motor Can Operate
+Two Valves with a Single Push Rod.]
+
+A carburetor of peculiar construction is employed in the Le Rhone
+engine, this being a very simple type as outlined at Fig. 221. It is
+attached to the threaded end of the hollow crank-shaft by a right and
+left coupling. The fuel is pumped to the spray nozzle, the opening in
+which is controlled by a fuel regulating needle having a long taper
+which is lifted out of the jet opening when the air-regulating slide is
+moved. The amount of fuel supplied the carburetor is controlled by a
+special needle valve fitting which combines a filter screen and which is
+shown at B. In regulating the speed of the Le Rhone engine, there are
+two possible means of controlling the mixture, one by altering the
+position of the air-regulating slide, which also works the metering
+needle in the jet, and the other by controlling the amount of fuel
+supplied to the spray nozzle through the special fitting provided for
+that purpose.
+
+[Illustration: Fig. 221.--The Le Rhone Carburetor at A and Fuel Supply
+Regulating Device at B.]
+
+In considering the action of this engine one can refer to Fig. 222. The
+crank O. M. is fixed, while the cylinders can turn about the crank-shaft
+center O and the piston turns around the crank-pin M, because of the
+eccentricity of the centers of rotation the piston will reciprocate in
+the cylinders. This distance is at its maximum when the cylinder is
+above O and at a minimum when it is above M, and the difference between
+these two positions is equal to the stroke, which is twice the distance
+of the crank-throw O, M. The explosion pressure resolves itself into the
+force F exerted along the line of the connecting rod A, M, and also into
+a force N, which tends to make the cylinders rotate around point O in
+the direction of the arrow. An odd number of cylinders acting on one
+crank-pin is desirable to secure equally spaced explosions, as the basic
+action is the same as the Gnome engine.
+
+[Illustration: Fig. 222.--Diagrams Showing Le Rhone Motor Action and
+Firing Order.]
+
+The magneto is driven by a gear having 36 teeth attached to crank-case
+which meshes with 16-tooth pinion on armature. The magneto turns at 2.25
+times crank-case speed. Two cams, one for inlet, one for exhaust, are
+mounted on a carrying member and act on nine rocker arms which are
+capable of giving a push-and-pull motion to the valve-actuating
+rocker-operating rods. A gear driven by the crank-case meshes with a
+larger member having internal teeth carried by the cam carrier. Each cam
+has five profiles and is mounted in staggered relation to the other.
+These give the nine fulcrumed levers the proper motion to open the inlet
+and exhaust valves at the proper time. The cams are driven at 45/50 or
+9/10 of the motor speed. The cylinder dimensions and timing follows; the
+weight can be approximated by figuring 3 pounds per horse-power.
+
+   80 H.P.     105 M/M bore       4.20" bore.
+               140 M/M stroke     5.60" stroke.
+
+  110 H.P.     112 M/M bore       4.48" bore.
+               170 M/M stroke     6.80" stroke.
+
+  Timing--Intake valve opening, lag     18°}             18°}
+          Intake valve closing, lag     35°}             35°}
+          Exhaust valve opening, lead   55°} 110 H.P.    45°} 80 H.P.
+          Exhaust valve closing, lag     5°}              5°}
+          Ignition time advance         26°}             26°}
+
+[Illustration: Fig. 223.--Diagram Showing Positions of Piston in Le
+Rhone Rotary Cylinder Motor.]
+
+
+THE RENAULT AIR-COOLED VEE ENGINE
+
+[Illustration: Fig. 224.--Diagrams Showing Valve Timing of Le Rhone
+Aviation Engine.]
+
+[Illustration: Fig. 225.--Diagrams Showing How Cylinder Cooling is
+Effected in Renault Vee Engines.]
+
+Air-cooled stationary engines are rarely used in airplanes, but the
+Renault Frères of France have for several years manufactured a complete
+series of such engines of the general design shown at Fig. 225, ranging
+from a low-powered one developed eight or nine years ago and rated at
+40 and 50 horse-power, to later eight-cylinder models rated at 70
+horse-power and a twelve-cylinder, or twin six, rated at 90 horse-power.
+The cylinders are of cast iron and are furnished with numerous cooling
+ribs which are cast integrally. The cylinder heads are separate
+castings and are attached to the cylinder as in early motorcycle engine
+practice, and serve to hold the cylinder in place on the aluminum alloy
+crank-case by a cruciform yoke and four long hold-down bolts (Fig. 226).
+The pistons are of cast steel and utilize piston rings of cast iron. The
+valves are situated on the inner side of the cylinder head, the
+arrangement being unconventional in that the exhaust valves are placed
+above the inlet. The inlet valves seat in an extension of the combustion
+head and are actuated by direct push rod and cam in the usual manner
+while an overhead gear in which rockers are operated by push rods is
+needed to actuate the exhaust valves. The valve action is clearly shown
+in Figs. 226 and 227. The air stream by which the cylinders are cooled
+is produced by a centrifugal or blower type fan of relatively large
+diameter which is mounted on the end of a crank-shaft and the air blast
+is delivered from this blower into an enclosed space between the
+cylinder from which it escapes only after passing over the cooling fins.
+In spite of the fact that considerable prejudice exists against
+air-cooling fixed cylinder engines, the Renault has given very good
+service in both England and France.
+
+[Illustration: Fig. 226.--End Sectional View of Renault Air-Cooled
+Aviation Engine.]
+
+[Illustration: Fig. 227.--Side Sectional View of Renault Twelve-Cylinder
+Air-Cooled Aviation Engine Crank-Case, Showing Use of Plain and Ball
+Bearings for Crank-Shaft Support.]
+
+As will be seen by the sectional view at Fig. 227, the steel crank-shaft
+is carried in a combination of plain bearings inside the crank-case and
+by ball bearings at the ends. Owing to air cooling, special precautions
+are taken with the lubrication system, though the lubrication is not
+forced or under high pressure. An oil pump of the gear-wheel type
+delivers oil from the sump at the bottom of the crank-case to a chamber
+above, from which the oil flows by gravity along suitable channels to
+the various main bearings. It flows from the bearings into hollow rings
+fastened to the crank-webs, and the oil thrown from the whirling
+connecting rod big ends bathes the internal parts in an oil mist. In the
+eight-cylinder designs ignition is effected by a magneto giving four
+sparks per revolution and is accordingly driven at engine speed. In the
+twelve-cylinder machine two magnetos of the ordinary revolving armature
+or two-spark type, each supplying six cylinders, are fitted as outlined
+at Fig. 228. The carburetor is a float feed form. Warm air is supplied
+for Winter and damp weather by air pipes surrounding the exhaust pipes.
+The normal speed of the Renault engine is 1,800 R. P. M., but as the
+propeller is mounted upon an extension of the cam-shaft the normal
+propeller speed is but half that of the engine, which makes it possible
+to use a propeller of large diameter and high efficiency. Owing to the
+air cooling, but low compression may be used, this being about 60 pounds
+per square inch, which, of course, lowers the mean effective pressure
+and makes the engine less efficient than water-cooled forms where it is
+possible to use compression pressure of 100 or more pounds per square
+inch. The 70 horse-power engine has cylinders with a bore of 3.78 inches
+and a stroke of 5.52 inches. Its weight is given as 396 pounds, when in
+running order, which figures 5.7 pounds per horse-power. The same
+cylinder size is used on the twelve-cylinder 100 horse-power and the
+stroke is the same. This engine in running order weighs 638 pounds,
+which figures approximately 6.4 pounds per B. H. P.
+
+[Illustration: Fig. 228.--End View of Renault Twelve-Cylinder Engine
+Crank-Case, Showing Magneto Mounting.]
+
+[Illustration: Fig. 229.--Diagram Outlining Renault Twelve-Cylinder
+Engine Ignition System.]
+
+
+SIMPLEX MODEL "A" HISPANO-SUIZA
+
+The Model A is of the water-cooled four-cycle Vee type, with eight
+cylinders, 4.7245 inch bore by 5.1182 inch stroke, piston displacement
+718 cubic inches. At sea-level it develops 150 horse-power at 1,450 R.
+P. M. It can be run successfully at much higher speeds, depending on
+propeller design and gearing, developing proportionately increased
+power. The weight, including carburetor, two magnetos, propeller hub,
+starting magneto and crank, but without radiator, water or oil or
+exhaust pipes, is 445 pounds. Average fuel consumption is .5 pound per
+horse-power hour and the oil consumption at 1,450 R. P. M. is three
+quarts per hour. The external appearance is shown at Fig. 230.
+
+Four cylinders are contained in each block, which is of built-up
+construction; the water jackets and valve ports are cast aluminum and
+the individual cylinders heat-treated steel forgings threaded into the
+bored holes of the aluminum castings. Each block after assembly is given
+a number of protective coats of enamel, both inside and out, baked on.
+Coats on the inside are applied under pressure. The pistons are aluminum
+castings, ribbed. Connecting rods are tubular, of the forked type. One
+rod bears directly on the crank-pin; the other rod has a bearing on the
+outside of the one first mentioned.
+
+The crank-shaft is of the five-bearing type, very short, stiff in
+design, bored for lightness and for the oiling system. The crank-shaft
+extension is tapered for the French standard propeller hub, which is
+keyed and locked to the shaft. This makes possible instant change of
+propellers. The case is in two halves divided on the center line of the
+crank-shaft, the bearings being fitted between the upper and lower
+sections. The lower half is deep, providing a large oil reservoir and
+stiffening the engine. The upper half is simple and provides magneto
+supports on extension ledges of the two main faces. The valves are of
+large diameter with hollow stems, working in cast iron bushings. They
+are directly operated by a single hollow cam-shaft located over the
+valves. The cam-shafts are driven from the crank-shaft by vertical
+shafts and bevel gears. The cam-shafts, cams and heads of the valve
+stems are all enclosed in oil-tight removable housings of cast aluminum.
+
+[Illustration: Fig. 230.--The Simplex Model A Hispano-Suiza Aviation
+Engine, a Very Successful Form.]
+
+Oiling is by a positive pressure system. The oil is taken through a
+filter and steel tubes cast in the case to main bearings, through
+crank-shaft to crank-pins. The fourth main bearing is also provided with
+an oil lead from the system and through tubes running up the end of each
+cylinder block, oil is provided for the cam-shafts, cams and bearings.
+The surplus oil escapes through the end of the cam-shaft where the
+driving gears are mounted, and with the oil that has gathered in the top
+casing, descends through the drive shaft and gears to the sump.
+
+Ignition is by two eight-cylinder magnetos firing two spark-plugs per
+cylinder. The magnetos are driven from each of the two vertical shafts
+by small bevel pinions meshing in bevel gears. The carburetor is mounted
+between the two cylinder blocks and feeds the two blocks through
+aluminum manifolds which are partly water-jacketed. The engine can be
+equipped with a geared hand crank-starting device.
+
+
+STURTEVANT MODEL 5A 140 HORSE-POWER ENGINE
+
+These motors are of the eight-cylinder "V" type, four-stroke cycle,
+water-cooled, having a bore of 4 inches and a stroke of 5-1/2 inches,
+equivalent to 102 mm. × 140 mm. The normal operating speed of the
+crank-shaft is 2,000 R. P. M. The propeller shaft is driven through
+reducing gears which can be furnished in different gear ratios. The
+standard ratio is 5:3, allowing a propeller speed of 1,200 R. P. M.
+
+The construction of the motor is such as to permit of the application of
+a direct drive. The change from the direct drive to gear drive, or vice
+versa, can be accomplished in approximately one hour.
+
+The cylinders are cast in pairs from an aluminum alloy and are provided
+with steel sleeves, carefully fitted into each cylinder. A perfect
+contact is secured between cylinder and sleeve; at the same time a
+sleeve can be replaced without injury to the cylinder proper. No
+difficulties due to expansion occur on account of the rapid transmission
+of heat and the fact that the sleeve is always at higher temperature
+than the cylinder. A moulded copper asbestos gasket is placed between
+the cylinder and the head, permitting the cooling water to circulate
+freely and at the same time insuring a tight joint. The cylinder heads
+are cast in pairs from an aluminum alloy and contain ample water
+passages for circulation of cooling water over the entire head. Trouble
+due to hot valves is thereby eliminated, a most important consideration
+in the operation of an aeroplane motor. The water jacket of the head
+corresponds to the water jacket of the cylinders and large openings in
+both allow the unobstructed circulation of the cooling water. The
+cylinder heads and cylinders are both held to the base by six long
+bolts. The valves are located in the cylinder heads and are mechanically
+operated. The valves and valve springs are especially accessible and of
+such size as to permit high volumetric efficiency. The valves are
+constructed of hardened tungsten steel, the heads and stems being made
+from one piece. The valve rocker arms located on the top of the cylinder
+are provided with adjusting screws. A check nut enables the adjusting
+screw to be securely locked in position, once the correct clearance has
+been determined. The rocker arm bearings are adequately lubricated by a
+compression grease cup. Cam-rollers are interposed between the cams and
+the push rods in order to reduce the side thrust on the push rods.
+
+A system of double springs is employed which greatly reduces the stress
+on each spring and insures utmost reliability. A spring of extremely
+large diameter returns the valve; a second spring located at the
+cylinder base handles the push rod linkage. These springs, which operate
+under low stress, are made from the best of steel and are given a
+special double heat treatment. The pistons are made from a special
+aluminum alloy; are deeply ribbed in the head for cooling and strength
+and provided with two piston rings. These pistons are exceedingly light
+weight in order to minimize vibration and prevent wear on the bearings.
+The piston pin is made of chrome nickel steel, bored hollow and
+hardened. It is allowed to turn, both in piston and connecting rod. The
+piston rings are of special design, developed after years of
+experimenting in aeronautical engines.
+
+The connecting rods are of "H" section, machined all over from forgings
+of a special air-hardening chrome nickel steel which, after being heat
+treated has a tensile strength of 280,000 pounds per square inch. They
+are consequently very strong and yet unusually light, and being machined
+all over are of absolutely uniform section, which gives as nearly
+perfect balance as can be obtained. The big ends are lined with white
+metal and the small ends are bushed with phosphor bronze. The connecting
+rods are all alike and take their bearings side by side on the
+crank-pin, the cylinders being offset to permit of this arrangement. The
+crank-shaft is machined from the highest grade chrome nickel steel, heat
+treated in order to obtain the best properties of this material. It is
+2-1/4 inches in diameter (57 mm.) and bored hollow throughout, insuring
+maximum strength with minimum weight. It is carried in three large,
+bronze-backed white metal bearings. A new method of producing these
+bearings insures a perfect bond between the two metals and eliminates
+breakage.
+
+The base is cast from an aluminum alloy. Great strength and rigidity is
+combined with light weight. The sides extend considerably below the
+center line of the crank-shaft, providing an extremely deep section. At
+all highly stressed points, deep ribs are provided to distribute the
+load evenly and eliminate bending. The lower half of the base is of cast
+aluminum alloy of extreme lightness. This collects the lubricating oil
+and acts as a small reservoir for same. An oil-filtering screen of large
+area covers the entire surface of the sump. The propeller shaft is
+carried on two large annular ball bearings driven from the crank-shaft
+by hardened chrome nickel steel spur gears. These gears are contained
+within an oil-tight casing integral with the base on the opposite end
+from the timing gears. A ball-thrust bearing is provided on the
+propeller shaft to take the thrust of a propeller or tractor, as the
+case may be. In case of the direct drive a stub shaft is fastened direct
+to the crank-shaft and is fitted with a double thrust bearing.
+
+The cam-shaft is contained within the upper half of the base between the
+two groups of cylinders, and is supported in six bronze bearings. It is
+bored hollow throughout and the cams are formed integral with the shaft
+and ground to the proper shape and finish. An important development in
+the shape of cams has resulted in a maintained increase of power at high
+speeds. The gears operating the cam-shaft, magneto, oil and water pumps
+are contained within an oil-tight casing and operate in a bath of oil.
+
+Lubrication is of the complete forced circulating system, the oil being
+supplied to every bearing under high pressure by a rotary pump of large
+capacity. This is operated by gears from the crank-shaft. The oil
+passages from the pump to the main bearings are cast integral with the
+base, the hollow crank-shaft forming a passage through the connecting
+rod bearings and the hollow cam-shaft distributing the oil to the
+cam-shaft bearings. The entire surface of the lower half of the base is
+covered with a fine mesh screen through which the oil passes before
+reaching the pump. Approximately one gallon of oil is contained within
+the base and this is continually circulated through an external tank by
+a secondary pump operated by an eccentric on the cam-shaft. This also
+draws fresh oil from the external tank which can be made of any desired
+capacity.
+
+
+SPECIFICATIONS--MODEL 5A TYPE 8
+
+  Horse-power rating, 140 at 2,000 R. P. M.
+  Bore, 4 inches = 102 mm.
+  Stroke, 5-1/2 inches = 140 mm.
+  Number of cylinders, 8.
+  Arrangement of cylinders, "V."
+  Cooling, water. Circulation by centrifugal pump.
+  Cycle, four stroke.
+  Ignition (double), 2 Bosch or Splitdorf magnetos.
+  Carburetor, Zenith duplex. Water jacket manifold.
+  Oiling system, complete forced. Circulating gear pump.
+  Normal crank-shaft speed, 2,000 R. P. M.
+  Propeller shaft, 3/5 crank-shaft speed at normal, 1,200 R. P. M.
+  Stated power at 30" barometer, 140 B. H. P.
+  Stated weight with all accessories but without water, gasoline or oil,
+  514 pounds = 234 kilos.
+  Weight per B. H. P., 3.7 pounds = 1.68 kilos.
+  Stated weight with all accessories with water, 550 pounds = 250 kilos.
+  Weight per B. H. P. with water, 3.95 pounds = 1.79 kilos.
+
+
+THE CURTISS AVIATION MOTORS
+
+The Curtiss OX motor has eight cylinders, 4-inch bore, 5-inch stroke,
+delivers 90 horse-power at 1,400 turns, and the weight turns out at 4.17
+pounds per horse-power. This motor has cast iron cylinders with monel
+metal jackets, overhead inclined valves operated by means of two rocker
+arms, push-and-pull rods from the central cam-shaft located in the
+crank-case. The cam and push rod design is extremely ingenious and the
+whole valve construction turns out very light. This motor is an
+evolution from the early Curtiss type motor which was used by Glenn
+Curtiss when he won the Gordon Bennett Cup at Rheims. A slightly larger
+edition of this type motor is the OXX-5, as shown at Figs. 231 and 232,
+which has cylinders 4-1/4 inches by 5 inches, delivers 100 horse-power
+at 1,400 turns and has the same fuel and oil consumption as the OX type
+motor, namely, .60 pound of fuel per brake horse-power hour and .03
+pound of lubricating oil per brake horse-power hour.
+
+[Illustration: Fig. 231.--The Curtiss OXX-5 Aviation Engine is an
+Eight-Cylinder Type Largely Used on Training Machines.]
+
+The Curtiss Company have developed in the last two years a larger-sized
+motor now known as the V-2, which was originally rated at 160
+horse-power and which has since been refined and improved so that the
+motor gives 220 horse-power at 1,400 turns, with a fuel consumption of
+52/100 of a pound per brake horse-power hour and an oil consumption of
+.02 of a pound per brake horse-power hour. This larger motor has a
+weight of 3.45 pounds per horse-power and is now said to be giving very
+satisfactory service. The V-2 motor has drawn steel cylinders, with a
+bore of 5 inches and a stroke of 7 inches, with a steel water jacket top
+and a monel metal cylindrical jacket, both of which are brazed on to the
+cylinder barrel itself. Both these motors use side by side connecting
+rods and fully forced lubrication. The cam-shafts act as a gallery from
+which the oil is distributed to the cam-shaft bearings, the main
+crank-shaft bearings, and the gearing. Here again we find extremely
+short rods, which, as before mentioned, enables the height and the
+consequent weight of construction to be very much reduced. For ordinary
+flying at altitudes of 5,000 to 6,000 feet, the motors are sent out with
+an aluminum liner, bolted between the cylinder and the crank-case in
+order to give a compression ratio which does not result in pre-ignition
+at a low altitude. For high flying, however, these aluminum liners are
+taken out and the compression volume is decreased to about 18.6 per
+cent. of the total volume.
+
+[Illustration: Fig. 232.--Top and Bottom Views of the Curtiss OXX-5 100
+Horse-Power Aviation Engine.]
+
+The Curtiss Aeroplane Company announces that it has recently built, and
+is offering, a twelve-cylinder 5" × 7" motor, which was designed for
+aeronautical uses primarily. This engine is rated at 250 horse-power,
+but it is claimed to develop 300 at 1,400 R. P. M. Weights--Motor, 1,125
+pounds; radiator, 120 pounds; cooling water, 100 pounds; propeller, 95
+pounds.
+
+Gasoline Consumption per Horse-power Hour, 6/10 pounds.
+
+Oil Consumption per Hour at Maximum Speed--2 pints.
+
+Installation Dimensions--Overall length, 84-5/8 inches; overall width,
+34-1/8 inches; overall depth, 40 inches; width at bed, 30-1/2 inches;
+height from bed, 21-1/8 inches; depth from bed, 18-1/2 inches.
+
+
+THOMAS-MORSE MODEL 88 ENGINE
+
+The Thomas-Morse Aircraft Corporation of Ithaca, N. Y., has produced a
+new engine, Model 88, bearing a close resemblance to the earlier model.
+The main features of that model have been retained; in fact, many parts
+are interchangeable in the two engines. Supported by the great
+development in the wide use of aluminum, the Thomas engineers have
+adopted this material for cylinder construction, which adoption forms
+the main departure from previous accepted design.
+
+The marked tendency to-day toward a higher speed of rotation has been
+conclusively justified, in the opinion of the Thomas engineers, by the
+continued reliable performance of engines with crank-shafts operating at
+speeds near 2,000 revolutions per minute, driving the propeller through
+suitable gearing at the most efficient speed. High speed demands that
+the closest attention be paid to the design of reciprocating and
+rotating parts and their adjacent units. Steel of the highest
+obtainable tensile strength must be used for connecting rods and piston
+pins, that they may be light and yet retain a sufficient factor of
+safety. Piston design is likewise subjected to the same strict scrutiny.
+At the present day, aluminum alloy pistons operate so satisfactorily
+that they may be said to have come to stay.
+
+The statement often made in the past, that the gearing down of an engine
+costs more in the weight of reduction gears and propeller shaft than is
+warranted by the increase in horse-power, is seldom heard to-day.
+
+The mean effective pressure remaining the same, the brake horse-power of
+any engine increases as the speed. That is, an engine delivering 100
+brake horse-power at 1,500 revolutions per minute will show 133 brake
+horse-power at 2,000 revolutions per minute, an increase of 33 brake
+horse-power. To utilize this increase in horse-power, a matter of some
+fifteen pounds must be spent in gearing and another fifteen perhaps on
+larger valves, bearings, etc. Two per cent. may be assumed lost in the
+gears. In other words, the increase in horse-power due to increasing the
+speed has been attained at the expense of about one pound per brake
+horse-power.
+
+The advantages of the eight-cylinder engine over the six and twelve,
+briefly stated, are: lower weight per horse-power, shorter length,
+simpler and stiffer crank-shaft, cam-shaft and crank-case, and simpler
+and more direct manifold arrangement. As to torque, the eight is
+superior to the six, and yet in practice not enough inferior to the
+twelve to warrant the addition of four more cylinders. It must, however,
+be recognized that the eight is subject to the action of inherent
+unbalanced inertia couples, which set up horizontal vibrations,
+impossible of total elimination. These vibrations are functions of the
+reciprocating weights, which, as already mentioned, are cut down to the
+minimum. Vibrations due to the elasticity of crank-case, crank-shaft,
+etc., can be and are reduced in the Thomas engine to minor quantities by
+ample webbing of the crank-case and judicious use of metal elsewhere.
+All things considered, there is actually so little difference to be
+discerned between the balance of a properly designed eight-cylinder
+engine and that of a six or twelve as to make a discussion of the pros
+and cons more one of theory than of practice.
+
+The main criticisms of the L head cylinder engine are that it is less
+efficient and heavier. This is granted, as it relates to cylinders
+alone. More thorough investigation, however, based on the main
+desideratum, weight-power ratio, leads us to other conclusions,
+particularly with reference to high speed engines. The valve gear must
+not be forgotten. A cylinder cannot be taken completely away from its
+component parts and judged, as to its weight value, by itself alone. A
+part away from the whole becomes an item unimportant in comparison with
+the whole. The valve gear of a high speed engine is a too often
+overlooked feature. The stamp of approval has been made by high speed
+automobile practice upon the overhead cam-shaft drive, with valves in
+the cylinder head operated direct from the cam-shaft or by means of
+valve lifters or short rockers.
+
+The overhead cam-shaft mechanism applied to an eight-cylinder engine
+calls for two separate cam-shafts carried above and supported by the
+cylinders in an oil-tight housing, and driven by a series of spur gears
+or bevels from the crank-shaft. It is patent that this valve gearing is
+heavy and complicated in comparison with the simple moving valve units
+of the L head engine, which are operated from one single cam-shaft,
+housed rigidly in the crank-case. The inherently lower volumetric
+efficiency of the L head engine is largely overcome by the use of a
+properly designed head, large valves and ample gas passages. Again, the
+customary use of a dual ignition system gives to the L head a relatively
+better opportunity for the advantageous placing of spark-plugs, in order
+that better flame propagation and complete combustion may be secured.
+
+[Illustration: Fig. 233.--End View of Thomas-Morse 150 Horse-Power
+Aluminum Cylinder Aviation Motor Having Detachable Cylinder Heads.]
+
+The Thomas Model 88 engine is 4-1/8 inch bore and 5-1/2 inch stroke. The
+cylinders and cylinder heads are of aluminum, and as steel liners are
+used in the cylinders the pistons are also made of aluminum. This engine
+is actually lighter than the earlier model of less power. It weighs but
+525 pounds, with self-starter. The general features of design can be
+readily ascertained by study of the illustrations: Fig. 233, which shows
+an end view; Fig. 234, which is a side view, and Fig. 235, which
+outlines the reduction gear-case and the propeller shaft supporting
+bearings.
+
+[Illustration: Fig. 234.--Side View of Thomas-Morse High Speed 150
+Horse-Power Aviation Motor with Geared Down Propeller Drive.]
+
+
+SIXTEEN-VALVE DUESENBERG ENGINE
+
+[Illustration: Fig. 235.--The Reduction Gear-Case of Thomas-Morse 150
+Horse-Power Aviation Motor, Showing Ball Bearing and Propeller Drive
+Shaft Gear.]
+
+This engine is a four-cylinder, 4-3/4" × 7", 125 horse-power at 2,100 R.
+P. M. of the crank-shaft and 1,210 R. P. M. of the propeller. Motors are
+sold on above rating; actual power tests prove this motor capable of
+developing 140 horse-power at 2,100 R. P. M. of the motor. The exact
+weight with magneto, carburetor, gear reduction and propeller hub, as
+illustrated, 509 pounds; without gear reduction, 436 pounds. This motor
+has been produced as a power plant weighing 3.5 pounds per horse-power,
+yet nothing has been sacrificed in rigidity and strength. At its normal
+speed it develops 1 horse-power for every 3.5 cubic inches piston
+displacement. Cylinders are semi-steel, with aluminum plates enclosing
+water jackets. Pistons specially ribbed and made of Magnalite aluminum
+compound. Piston rings are special Duesenberg design, being three-piece
+rings. Valves are tungsten steel, 1-15/16" inlets and 2" exhausts, two
+of each to each cylinder. Arranged horizontally in the head, allowing
+very thorough water-jacketing. Inlet valves in cages. Exhaust valves,
+seating directly in the cylinder head, are removable through the inlet
+valve holes. Valve stems lubricated by splash in the valve action
+covers. Valve rocker arms forged with cap screw and nut at upper end to
+adjust clearance. Entirely enclosed by aluminum housing, as is entire
+valve mechanism. Connecting rods are tubular, chrome nickel steel, light
+and strong. Crank-shaft is one-piece forging, hollow bored, 2-1/2-inch
+diameter at main bearings. Connecting rod bearings, 2-1/4-inch diameter,
+3 inches long. Front main bearing, 3-1/2 inches long; intermediate main
+bearing, 3-1/2 inches long; rear main bearing, 4 inches long. Crank-case
+of aluminum, barrel type, oil pan on bottom removable. Hand hole plates
+on both sides. Strongly webbed.
+
+The oiling system of this sixteen-valve Duesenberg motor is one of its
+vital features. An oil pump located in the base and submerged in oil
+forces oil through cored passages to the three main bearings, then
+through tubes under each connecting rod into which the rod dips. The oil
+is thrown off from these and lubricates every part of the motor. This
+constitutes the main oiling system; it is supplemented by a splash
+system, there being a trough under each connecting rod into which the
+rod slips. The oil is returned to the main supply sump by gravity, where
+it is strained and re-used. Either system is in itself sufficient to
+operate the motor. A pressure gauge is mounted for observation on a
+convenient part of the system. A pressure of approximately 25 pounds is
+maintained by the pressure system, which insures efficient lubrication
+at all speeds of the motor. The troughs under the connecting rods are so
+constructed that no matter what the angle of flight may be, oil is
+retained in each individual trough so that each connecting rod can dip
+up its supply of oil at each revolution.
+
+
+AEROMARINE SIX-CYLINDER VERTICAL MOTOR
+
+[Illustration: Fig. 236.--The Six-Cylinder Aeromarine Engine.]
+
+These motors are four-stroke cycle, six-cylinder vertical type, with
+cylinder 4-5/16" bore by 5-1/8" stroke. The general appearance of this
+motor is shown in illustration at Fig. 236. This engine is rated at
+85-90 horse-power. All reciprocating and revolving parts of this motor
+are made of the highest grades of steel obtainable as are the studs,
+nuts and bolts. The upper and lower parts of crank-case are made of
+composition aluminum casting. Lower crank-case is made of high grade
+aluminum composition casting and is bolted directly to the upper half.
+The oil reservoir in this lower half casting provides sufficient oil
+capacity for five hours' continuous running at full power. Increased
+capacity can be provided if needed to meet greater endurance
+requirements. Oil is forced under pressure to all bearings by means of
+high-pressured duplex-geared pumps. One side of this pump delivers oil
+under pressure to all the bearings, while the other side draws the oil
+from the splash case and delivers it to the main sump. The oil reservoir
+is entirely separate from the crank-case chamber. Under no circumstances
+will oil flood the cylinder, and the oiling system is not affected in
+any way by any angle of flight or position of motor. An oil pressure
+gauge is placed on instrument board of machine, which gives at all
+times the pressure in oil system, and a sight glass at lower half of
+case indicates the amount of oil contained. The oil pump is external on
+magneto end of motor, and is very accessible. An external oil strainer
+is provided, which is removable in a few minutes' time without the loss
+of any oil. All oil from reservoir to the motor passes through this
+strainer. Pressure gauge feed is also attached and can be piped to any
+part of machine desired.
+
+The cylinders are made of high-grade castings and are machined and
+ground accurately to size. Cylinders are bolted to crank-case with
+chrome nickel steel studs and nuts which securely lock cylinder to upper
+half of crank-case. The main retaining cylinder studs go through
+crank-case and support crank-shaft bearings so that crank-shaft and
+cylinders are tied together as one unit. Water jackets are of copper,
+1/16" thick, electrically deposited. This makes a non-corrosive metal.
+Cooling is furnished by a centrifugal pump, which delivers 25 gallons
+per minute at 1,400 R. P. M. Pistons are made cast iron, accurately
+machined and ground to exact dimensions, which are carefully balanced.
+Piston rings are semi-steel rings of Aeromarine special design.
+
+Connecting rods are of chrome nickel steel, H-section. Crank-shaft is
+made of chrome nickel steel, machined all over, and cut from solid
+billet, and is accurately balanced through the medium of balance weights
+being forged integral with crank. It is drilled for lightness and
+plugged for force feed lubrication. There are seven main bearings to
+crank-shaft. All bearings are of high-grade babbitt, die cast, and are
+interchangeable and easily replaced. The main bearings of the
+crank-shaft are provided with a single groove to take oil under pressure
+from pressure tube which is cast integral with case. Connecting rod
+bearings are of the same type. The gudgeon pin is hardened, ground and
+secured in connecting rod, and is allowed to work in piston. Cam-shaft
+is of steel, with cams forged integral, drilled for lightness and
+forced-feed lubrication, and is case-hardened. The bearings of
+cam-shaft are of bronze. Magneto, two high-tension Bosch D. U. 6. The
+intake manifold for carburetors are aluminum castings and are so
+designed that each carburetor feeds three cylinders, thereby insuring
+easy flow of vapor at all speeds. Weight, 420 pounds.
+
+[Illustration: Fig. 237.--The Wisconsin Aviation Engine, at Top, as
+Viewed from Carburetor Side. Below, the Exhaust Side.]
+
+
+WISCONSIN AVIATION ENGINES
+
+[Illustration: Fig. 238.--Dimensioned End Elevation of Wisconsin Six
+Motor.]
+
+The new six-cylinder Wisconsin aviation engines, one of which is shown
+at Fig. 237, are of the vertical type, with cylinders in pairs and
+valves in the head. Dimensioned drawings of the six-cylinder vertical
+type are given at Figs. 238 and 239. The cylinders are made of aluminum
+alloy castings, are bored and machined and then fitted with hardened
+steel sleeves about 1/16 inch in thickness. After these sleeves have
+been shrunk into the cylinders, they are finished by grinding in place.
+Gray iron valve seats are cast into the cylinders. The valve seats and
+cylinders, as well as the valve ports, are entirely surrounded by water
+jackets. The valves set in the heads at an angle of 25° from the
+vertical, are made of tungsten steel and are provided with double
+springs, the outer or main spring and the inner or auxiliary spring,
+which is used as a precautionary measure to prevent a valve falling into
+the cylinder in remote case of a main spring breaking. The cam-shaft is
+made of one solid forging, case-hardened. It is carried in an aluminum
+housing bolted to the top of the cylinders. This housing is split
+horizontally, the upper half carrying the chrome vanadium steel rocker
+levers. The lower half has an oil return trough cast integral, into
+which the excess oil overflows and then drains back to the crank-case.
+Small inspection plates are fitted over the cams and inner ends of the
+cam rocker levers. The cam-shaft runs in bronze bearings and the drive
+is through vertical shaft and bevel gears.
+
+[Illustration: Fig. 239.--Dimensioned Side Elevation of Wisconsin Six
+Motor.]
+
+The crank-case is made of aluminum, the upper half carrying the
+bearings for the crank-shaft. The lower half carries the oil sump in
+which all of the oil except that circulating through the system at the
+time is carried. The crank-shaft is made of chrome vanadium steel of an
+elastic limit of 115,000 pounds. The crank-pins and ends of the shaft
+are drilled for lightness and the cheeks are also drilled for oil
+circulation. The crank-shaft runs in bronze-backed, Fahrig metal-lined
+bearings, four in number. A double thrust bearing is also provided, so
+that the motor may be used either in a tractor or pusher type of
+machine. Outside of the thrust bearing an annular ball bearing is used
+to take the radial load of the propeller. The propeller is mounted on a
+taper. At the opposite end of the shaft a bevel gear is fitted which
+drives the cam-shaft, through a vertical shaft, and also drives the
+water and oil pumps and magnetos. All gears are made of chrome vanadium
+steel, heat-treated.
+
+The connecting rods are tubular and machined from chrome vanadium steel
+forgings. Oil tubes are fitted to the rods which carry the oil up to the
+wrist-pins and pistons. The rods complete with bushings weigh 5-1/2
+pounds each. The pistons are made of aluminum alloy and are very light
+and strong, weighing only 2 pounds 2 ounces each. Two leak-proof rings
+are fitted to each piston. The wrist-pins are hollow, of hardened steel,
+and are free to turn either in the piston or the rod. A bronze bushing
+is fitted in the upper end of the rod, but no bushing is fitted in the
+pistons, the hardened steel wrist-pins making an excellent bearing in
+the aluminum alloy.
+
+[Illustration: Fig. 240.--Power, Torque and Efficiency Curves of
+Wisconsin Aviation Motor.]
+
+The water circulation is by centrifugal pump, which is mounted at the
+lower end of the vertical shaft. The water is pumped through brass pipes
+to the lower end of the cylinder water jackets and leaves the upper end
+of the jackets just above the exhaust valves. The lubricating system is
+one of the main features of the engines, being designed to work with the
+motor at any angle. The oil is carried in the sump, from where it is
+taken by the oil circulating pump through a strainer and forced through
+a header, extending the full length of the crank-case, and distributed
+to the main bearings. From the main bearings it is forced through the
+hollow crank-shaft to the connecting rod big ends and then through
+tubes on the rods to wrist-pins and pistons. Another lead takes oil from
+the main header to the cam-shaft bearings. The oil forced out of the
+ends of the cam-shaft bearings fills pockets under the cams and in the
+cam rocker levers. The excess flows back through pipes and through the
+train of gears to the crank-case. A strainer is fitted at each end of
+the crank-case, through which the oil is drawn by separate pumps and
+returned to the sump. Either one of these pumps is large enough to take
+care of all of the return oil, so that the operation is perfect whether
+the motor is inclined up or down. No splash is used in the crank-case,
+the system being a full force feed. An oil level indicator is provided,
+showing the amount of oil in the sump at all times. The oil pressure in
+these motors is carried at ten pounds, a relief valve being fitted to
+hold the pressure constant.
+
+[Illustration: Fig. 241.--Timing Diagram, Wisconsin Aviation Engine.]
+
+Ignition is by two Bosch magnetos, each on a separate set of plugs fired
+simultaneously on opposite sides of the cylinders. Should one magneto
+fail, the other would still run the engine at only a slight loss in
+power. The Zenith double carburetor is used, three cylinders being
+supplied by each carburetor. This insures a higher volumetric
+efficiency, which means more power, as there is no overlapping of inlet
+valves whatever by this arrangement. All parts of these motors are very
+accessible. The water and oil pumps, carburetors, magnetos, oil strainer
+or other parts can be removed without disturbing other parts. The lower
+crank-case can be removed for inspection or adjustment of bearings, as
+the crank-shaft and bearing caps are carried by the upper half. The
+motor supporting lugs are also part of the upper crank-case.
+
+The six-cylinder motor, without carburetors or magnetos, weighs 547
+pounds. With carburetor and magnetos, the weight is 600 pounds. The
+weight of cooling water in the motor is 38 pounds. The sump will carry 4
+gallons of oil, or about 28 pounds. A radiator can be furnished suitable
+for the motor, weighing 50 pounds. This radiator will hold 3 gallons of
+water or about 25 pounds. The motor will drive a two-blade, 8 feet
+diameter by 6.25 feet pitch Paragon propeller 1400 revolutions per
+minute, developing 148 horse-power. The weight of this propeller is 42
+pounds. This makes a total weight of motor, complete with propeller,
+radiator filled with water, but without lubricating oil, 755 pounds, or
+about 5.1 pounds per horse-power for complete power plant. The fuel
+consumption is .5 pound per horse-power per hour. The lubricating oil
+consumption is .0175 pound per horse-power per hour, or a total of 2.6
+pounds per hour at 1400 revolutions per minute. This would make the
+weight of fuel and oil, per hour's run at full power at 1400 revolutions
+per minute, 76.6 pounds.
+
+
+PRINCIPAL DIMENSIONS
+
+Following are the principal dimensions of the six-cylinder motor:
+
+  Bore 5 inches.
+  Stroke 6-1/2 inches.
+  Crank-shaft diameter throughout 2 inches.
+  Length of crank-pin and main bearings 3-1/2 inches.
+  Diameter of valves 3 inches (2-3/4 inches clear).
+  Lift of valves 1/2 inch.
+  Volume of compression space 22 per cent. of total.
+  Diameter of wrist-pins 1-3/16 inches.
+  Firing order 1-4-2-6-3-5.
+
+The horse-power developed at 1200 revolutions per minute is 130, at 1300
+revolutions per minute 140, at 1400 revolutions per minute 148. 1400 is
+the maximum speed at which it is recommended to run these motors.
+
+
+TWELVE-CYLINDER ENGINE
+
+A twelve-cylinder V-type engine illustrated, is also being built by this
+company, similar in dimensions of cylinders to the six. The principal
+differences being in the drive to cam-shaft, which is through spur gears
+instead of bevel. A hinged type of connecting rod is used which does not
+increase the length of the motor and, at the same time, this
+construction provides for ample bearings. A double centrifugal water
+pump is provided for this motor, so as to distribute the water uniformly
+to both sets of cylinders. Four magnetos are used, two for each set of
+six cylinders. The magnetos are very accessibly located on a bracket on
+the spur gear cover. The carburetors are located on the outside of the
+motors, where they are very accessible, while the exhaust is in the
+center of the valley. The crank-shaft on the twelve is 2-1/2 inches in
+diameter and the shaft is bored to reduce weight. Dimensioned drawings
+of the twelve-cylinder engine are given at Figs. 242 and 243 and should
+prove useful for purposes of comparison with other motors.
+
+
+HALL-SCOTT AVIATION ENGINES
+
+The following specifications of the Hall-Scott "Big Four" engines apply
+just as well to the six-cylinder vertical types which are practically
+the same in construction except for the structural changes necessary to
+accommodate the two extra cylinders. Cylinders are cast separately from
+a special mixture of semi-steel, having cylinder head with valve seats
+integral. Special attention has been given to the design of the water
+jacket around the valves and head, there being two inches of water space
+above same. The cylinder is annealed, rough machined, then the inner
+cylinder wall and valve seats ground to mirror finish. This adds to the
+durability of the cylinder, and diminishes a great deal of the excess
+friction.
+
+[Illustration: Fig. 242.--Dimensioned End View of Wisconsin
+Twelve-Cylinder Airplane Motor.]
+
+Great care is taken in the casting and machining of these cylinders, to
+have the bore and walls concentric with each other. Small ribs are cast
+between outer and inner walls to assist cooling as well as to transfer
+stresses direct from the explosion to hold-down bolts which run from
+steel main bearing caps to top of cylinders. The cylinders are machined
+upon the sides so that when assembled on the crank-case with grooved
+hold-down washers tightened, they form a solid block, greatly assisting
+the rigidity of crank-case.
+
+[Illustration: Fig. 243.--Dimensioned Side Elevation of Wisconsin
+Twelve-Cylinder Airplane Motor.]
+
+The connecting rods are very light, being of the I beam type, milled
+from a solid Chrome nickel die forging. The caps are held on by two
+1/2"-20 thread Chrome nickel through bolts. The rods are first roughed
+out, then annealed. Holes are drilled, after which the rods are hardened
+and holes ground parallel with each other. The piston end is fitted with
+a gun metal bushing, while the crank-pin end carries two bronze serrated
+shells, which are tinned and babbitted hot, being broached to harden the
+babbitt. Between the cap and rod proper are placed laminated shims for
+adjustment. Crank-cases are cast of the best aluminum alloy, hand
+scraped and sand blasted inside and out. The lower oil case can be
+removed without breaking any connections, so that the connecting rods
+and other working parts can readily be inspected. An extremely large
+strainer and dirt trap is located in the center and lowest point of the
+case, which is easily removed from the outside without disturbing the
+oil pump or any working parts. A Zenith carburetor is provided.
+Automatic valves and springs are absent, making the adjustment simple
+and efficient. This carburetor is not affected by altitude to any
+appreciable extent. A Hall-Scott device, covered by U. S. Patent No.
+1,078,919, allows the oil to be taken direct from the crank-case and run
+around the carburetor manifold, which assists carburetion as well as
+reduces crank-case heat. Two waterproof four-cylinder Splitdorf "Dixie"
+magnetos are provided. Both magneto interruptors are connected to a rock
+shaft integral with the motor, making outside connections unnecessary.
+It is worthy of note that with this independent double magneto system,
+one complete magneto can become inoperative, and still the motor will
+run and continue to give good power.
+
+The pistons as provided in the A-7 engines are cast from a mixture of
+steel and gray iron. These are extremely light, yet provided with six
+deep ribs under the arch head, greatly aiding the cooling of the piston
+as well as strengthening it. The piston pin bosses are located very low
+in order to keep the heat from the piston head away from the upper end
+of the connecting rod, as well as to arrange them at the point where the
+piston fits the cylinder best. Three 1/4" rings are carried. The pistons
+as provided in the A-7a engines are cast from aluminum alloy. Four 1/4"
+rings are carried. In both piston types a large diameter, heat treated,
+Chrome nickel steel wrist-pin is provided, assembled in such a way as to
+assist the circular rib between the wrist-pin bosses to keep the piston
+from being distorted from the explosions.
+
+The oiling system is known as the high pressure type, oil being forced
+to the under side of the main bearings with from 5 to 30 points
+pressure. This system is not affected by extreme angles obtained in
+flying, or whether the motor is used for push or pull machines. A large
+gear pump is located in the lowest point of the oil sump, and being
+submerged at all times with oil, does away with troublesome stuffing
+boxes and check valves. The oil is first drawn from the strainer in oil
+sump to the long jacket around the intake manifold, then forced to the
+main distributor pipe in crank-case, which leads to all main bearings. A
+bi-pass, located at one end of the distributor pipe, can be regulated to
+provide any pressure required, the surplus oil being returned to the
+case. A special feature of this system is the dirt, water and sediment
+trap, located at the bottom of the oil sump. This can be removed without
+disturbing or dismantling the oil pump or any oil pipes. A small oil
+pressure gauge is provided, which can be run to the aviator's instrument
+board. This registers the oil pressure, and also determines its
+circulation.
+
+The cooling of this motor is accomplished by the oil as well as the
+water, this being covered by patent No. 1,078,919. This is accomplished
+by circulating the oil around a long intake manifold jacket; the
+carburetion of gasoline cools this regardless of weather conditions.
+Crank-case heat is therefore kept at a minimum. The uniform temperature
+of the cylinders is maintained by the use of ingenious internal outlet
+pipes, running through the head of each of the six-cylinders, rubber
+hose connections being used so that any one of the cylinders may be
+removed without disturbing the others. Slots are cut in these pipes so
+that cooler water is drawn directly around the exhaust valves. Extra
+large water jackets are provided upon the cylinders, two inches of water
+space is left above the valves and cylinder head. The water is
+circulated by a large centrifugal pump insuring ample circulation at all
+speeds.
+
+The crank-shaft is of the five bearing type, being machined from a
+special heat treated drop forging of the highest grade nickel steel. The
+forging is first drilled, then roughed out. After this the shaft is
+straightened, turned down to a grinding size, then ground accurately to
+size. The bearing surfaces are of extremely large size, over-size,
+considering general practice in the building of high speed engines of
+similar bore and stroke. The crank-shaft bearings are 2" in diameter by
+1-15/16" long, excepting the rear main bearing, which is 4-3/8" long,
+and front main bearing, which is 2-3/16" long. Steel oil scuppers are
+pinned and sweated onto the webs of the shaft, which allows of properly
+oiling the connecting rod bearings. Two thrust bearings are installed on
+the propeller end of the shaft, one for pull and the other for push. The
+propeller is driven by the crank-shaft flange, which is securely held in
+place upon the shaft by six keys. These drive an outside propeller
+flange, the propeller being clamped between them by six through bolts.
+The flange is fitted to a long taper on crank-shaft. This enables the
+propeller to be removed without disturbing the bolts. Timing gears and
+starting ratchets are bolted to a flange turned integral with shaft.
+
+The cam-shaft is of the one piece type, air pump eccentric, and gear
+flange being integral. It is made from a low carbon specially heat
+treated nickel forging, is first roughed out and drilled entire length;
+the cams are then formed, after which it is case hardened and ground to
+size. The cam-shaft bearings are extra long, made from Parson's White
+Brass. A small clutch is milled in gear end of shaft to drive revolution
+indicator. The cam-shaft is enclosed in an aluminum housing bolted
+directly on top of all six cylinders, being driven by a vertical shaft
+in connection with bevel gears. This shaft, in conjunction with rocker
+arms, rollers and other working parts, are oiled by forcing the oil into
+end of shaft, using same as a distributor, allowing the surplus supply
+to flow back into the crank-case through hollow vertical tube. This
+supply oils the magneto and pump gears. Extremely large Tungsten valves,
+being one-half the cylinder diameter, are seated in the cylinder heads.
+Large diameter oil tempered springs held in tool steel cups, locked with
+a key, are provided. The ports are very large and short, being designed
+to allow the gases to enter and exhaust with the least possible
+resistance. These valves are operated by overhead one piece cam-shaft in
+connection with short Chrome nickel rocker arms. These arms have
+hardened tool steel rollers on cam end with hardened tool steel
+adjusting screws opposite. This construction allows accurate valve
+timing at all speeds with least possible weight.
+
+
+CENSORED
+
+
+GERMAN AIRPLANE MOTORS
+
+In a paper on "Aviation Motors," presented by E. H. Sherbondy before the
+Cleveland section of the S. A. E. in June, 1917, the Mercedes and Benz
+airplane motor is discussed in some detail and portions of the
+description follow.
+
+[Illustration: Fig. 244.--Side and End Sectional Views of Four-Cylinder
+Argus Engine, a German 100 Horse-Power Design Having Bore and Stroke of
+140 mm., or 5.60 inches, and Developing Its Power at 1,368 R.P.M.
+Weight, 350 Pounds.]
+
+
+MERCEDES MOTOR
+
+The 150 horse-power six-cylinder Mercedes motor is 140 millimeters bore
+and 160 millimeters stroke. The Mercedes company started with
+smaller-sized cylinders, namely 100 millimeters bore and 140 millimeters
+stroke, six-cylinders. The principal features of the design are forged
+steel cylinders with forged steel elbows for gas passages, pressed steel
+water jackets, which when welded together forms the cylinder
+assembly, the use of inclined overhead valves operated by means of an
+overhead cam-shaft through rocker arms which multiply with the motion of
+the cam. By the use of steel cylinders, not only is the weight greatly
+reduced, but certain freedom from distortion through unequal sections,
+leaks and cracks are entirely avoided. The construction is necessarily
+very expensive. It is certainly a sound job. In the details of this
+construction there are a number of important things, such as finished
+gas passages, water-cooled valve guides and a very small mass of metal,
+which is water-cooled, surrounding the spark-plug. Of course, it is
+necessary to use very high compression in aviation motors in order to
+secure high power and economy and owing to the fact that aviation motors
+are worked at nearly their maximum, the heat flow through the cylinder,
+piston, and valves is many times higher than that encountered in
+automobile motors. It has been found necessary to develop special types
+of pistons to carry the heat from the center of the head in order to
+prevent pre-ignition. In the Mercedes motor the pistons have a drop
+forged steel head which includes the piston boss and this head is
+screwed into a cast iron skirt which has been machined inside to secure
+uniform wall thickness.
+
+
+CENSORED
+
+
+  [A] Piston Displacement (Cubic Inches)
+  [B] Weight of Engine with Carburetor and Ignition
+  [C] Gas Consumption
+
+  ===========+======+======+======+=======+====+======+====+=================
+  Maker's    |Number|Bore  |Stroke|       |    |      |    |
+  Name       |  of  |(In-  |(In-  |       |    |      |    |
+  and Model  | Cyl. |ches) |ches) |  [A]  |H.P.|R.P.M.| [B]|       [C]
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Aeromarine |   6  |4-1/2 |5-1/8 | 449   |  85| 1400 | 440|       ...
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Aeromarine |  12  |4-5/16|5-1/8 |  ...  | ...| ...  | 750|       ...
+  D-12       |      |      |      |       |    |      |    |
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Curtiss OX |   8  |4     |5     | 502.6 |  90| 1400 | 375|       ...
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Curtiss    |   8  |4-1/4 |5     | 567.5 | 100| 1400 | 423|       ...
+  OXX-2      |      |      |      |       |    |      |    |
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Curtiss V-2|   8  |5     |7     |1100   | 200| 1400 | 690|       ...
+  -----------+------+------+------+-------+----+------+----+-----------------
+                                   CENSORED
+  -----------+------+------+------+-------+----+------+----+-----------------
+  General Ve-|   9  |4.33  |5.9   | 848   | 100| 1200 | 272|12 gals/hour at
+  hicle Gnome Mono  |      |      |       |    |      |    |rated H.P.
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Gyro K     |   7  |4-1/2 |6     | ...   |  90|  1250| 215|8 gals/hour at
+  Rotary, Le Rhone Type    |      |       |    |      |    |rated H.P.
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Gyro L     |   9  |4-1/2 |6     | 859   | 100|  1200| 285|10 gals/hour at
+  Rotary, Le Rhone Type    |      |       |    |      |    |rated H.P.
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Hall-Scott |   4  |5     |7     | 550   | 90-|  1400| 410|       ...
+  A-7        |      |      |      |       | 100|      |    |
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Hall-Scott |   6  |5     |7     | 825   | 125|  1300| 592|       ...
+  A-5        |      |      |      |       |    |      |    |
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Hispano-   |   8  |4-5/8 |5     | 672   | 154|  1500| 455|       ...
+  Suiza      |      |      |      |       |    |      |    |
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Knox Motors|  12  |4-3/4 |7     |1555   | 300|  1800|1425|31.5 gals/hour
+  Co.        |      |      |      |       |    |      |    |
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Maximotor  |   6  |4-1/2 |5     | 477   |  85|  1600| 340|       ...
+  A-6        |      |      |      |       |    |      |    |
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Maximotor  |   6  |5     |6     | 706.8 | 115|  1600| 385|       ...
+  B-6        |      |      |      |       |    |      |    |
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Maximotor  |   8  |4-1/2 |5     | 636   | 115|  1600| 420|       ...
+  A-8        |      |      |      |       |    |      |    |
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Packard 12 |  12  |4     |6     | 903   | 225|  2100| 800|       ...
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Sturtevant |   8  |4     |5-1/2 | 552.9 | 140|  2000| 580|       ...
+  5          |      |      |      |       |    |      |    |
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Sturtevant |   8  |4     |5-1/2 | ...   | 140|  2000| 514|13.75 gals/hour
+  5-A        |      |      |      |       |    |      |    |
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Thomas 8   |   8  |4     |5-1/2 | 552.9 | 135|  2000| 630|       ...
+             |      |      |      |       |    |      |lbs. with self-starter
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Thomas 88  |   8  |4-1/8 |5-1/2 | 552.9 | 150|  2100| 525|       ...
+             |      |      |      |       |    |      |lbs. with self-starter
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Wisconsin  |   6  |5     |6-1/2 | 765.7 | 140|  1380| 637|       ...
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Wisconsin  |  12  |5     |6-1/2 |1531.4 | 250|  1200| ...|       ...
+  -----------+------+------+------+-------+----+------+----+-----------------
+
+The carburetor used on this 150 horse-power Mercedes motor is precisely
+of the same type used on the Twin Six motor. It has two venturi throats,
+in the center of which is placed the gasoline spray nozzle of
+conventional type, fixed size orifices, immediately above which are
+placed two panel type throttles with side outlets. An idling or primary
+nozzle is arranged to discharge above the top of the venturi throat. The
+carburetor body is of cast aluminum and is water jacketed. It is bolted
+directly to air passage passing through the top and bottom half of the
+crank-case which passes down through the oil reservoir. The air before
+reaching the carburetor proper to some extent has cooled the oil in the
+crank chamber and has itself been heated to assist in the vaporization.
+The inlet pipes themselves are copper. All the passages between the
+venturi throat and the inlet valve have been carefully finished and
+polished. The only abnormal thing in the design of this motor is the
+short connecting rod which is considerably less than twice the stroke
+and would be considered very bad practice in motor car engines. A short
+connecting rod, however, possesses two very real virtues in that it cuts
+down height of the motor and the piston passes over the bottom dead
+center much more slowly than with a long rod.
+
+[Illustration: Fig. 245.--Part Sectional View of 90 Horse-Power Mercedes
+Engine, Which is Typical of the Design of Larger Sizes.]
+
+Other features of the design are a very stiff crank-case, both halves of
+which are bolted together by means of long through bolts, the
+crank-shaft main bearings are seated in the lower half of the case
+instead of in the usual caps and no provision is made for taking up the
+main bearings. The Mercedes company uses a plunger type of pump having
+mechanically operated piston valves and it is driven by means of worm
+gearing.
+
+The overhead cam-shaft construction is extremely light. The cam-shaft is
+mounted in a nearly cylindrical cast bronze case and is driven by means
+of bevel gears from the crank-shaft. The vertical bevel gear shaft
+through which the drive is taken from the crank-shaft to the cam-shaft
+operates at one and one-half times the crank-shaft speeds and the
+reduction to the half-time cam-shaft is secured through a pair of
+bevels. On this vertical shaft there is mounted the water pump and a
+bevel gear for driving two magnetos. The water pump mounted on this
+shaft tends to steady the drive and avoid vibration in the gearing.
+
+The cylinder sizes of six-cylinder aviation motors which have been built
+by Mercedes are
+
+   Bore      Stroke    Horse-power
+  105 mm.    140 mm.       100
+  120 mm.    140 mm.       135
+  140 mm.    150 mm.       150
+  140 mm.    160 mm.       160
+
+The largest of these motors has recently had its horse-power increased
+to 176 at 1450 R. P. M. This general design of motor has been the
+foundation for a great many other aviation motor designs, some of which
+have proved very successful but none of which is equal to the original.
+Among the motors which follow more or less closely the scheme of design
+and arrangement are the Hall-Scott, the Wisconsin motor, the Renault
+water-cooled, the Packard, the Christofferson and the Rolls-Royce. Each
+of these motors show considerable variation in detail. The Rolls-Royce
+and Renault are the only ones who have used the steel cylinder with the
+steel jacket. The Wisconsin motor uses an aluminum cylinder with a
+hardened steel liner and cast-iron valve seats. The Christofferson has
+somewhat similar design to the Wisconsin with the exception that the
+valve seats are threaded into the aluminum jacket and the cylinder head
+has a blank end which is secured to the aluminum casting by means of the
+valve seat pieces. The Rolls-Royce motors show small differences in
+details of design in cylinder head and cam-shaft housing from the
+Mercedes on which it has taken out patents, not only abroad but in this
+country.
+
+
+THE BENZ MOTOR
+
+In the Kaiser prize contest for aviation motors a four-cylinder Benz
+motor of 130 by 180 mm. won first prize, developing 103 B. H. P. at 1290
+R. P. M. The fuel consumption was 210 grams per horse-power hour. Total
+weight of the motor was 153 kilograms. The oil consumption was .02 of a
+kilogram per horse-power hour. This motor was afterward expanded into a
+six-cylinder design and three different sizes were built.
+
+The accompanying table gives some of the details of weight, horse-power,
+etc.
+
+  Motor type                                    B      FD      FF
+  Rated horse-power                            85     100     150
+  Horse-power at 1250 r.p.m                    88     108     150
+  Horse-power at 1350 r.p.m                    95     115     160
+  Bore in millimeters                         106     116     130
+  Stroke in millimeters                       150     160     180
+  Offset of the cylinders in millimeters       18      20      20
+  Rate of gasoline consumption in grams       240     230     225
+  Oil consumption in grams per b.h.p. hour     10      10      10
+  Oil capacity in kilograms                    36       4       4-1/2
+  Water capacity in litres                      5-1/2   7-1/2   9-1/2
+  The weight with water and oil but with
+  two magnetos, fuel feeder and air pump in
+  kilograms                                   170     200     245
+  The weight of motors, including the water
+  pump, two magnetos, double ignition, etc.   160     190     230
+  The weight of the exhaust pipe, complete
+  in kilograms                                  4       4.8     5-1/2
+  The weight of the propeller hub in
+  kilograms.                                    3-1/2   4       4
+
+The Benz cylinder is a simple, straightforward design and a very
+reliable construction and not particularly difficult to manufacture. The
+cylinder is cast of iron without a water jacket but including 45
+degrees angle elbows to the valve ports. The cylinders are machined
+wherever possible and at other points have been hand filed and scraped,
+after which a jacket, which is pressed in two halves, is gas welded by
+means of short pipes welded on to the jacket. The bottom and the top of
+the cylinders become water galleries, and by this means separate water
+pipes with their attendant weight and complication are eliminated.
+Rubber rings held in aluminum clamps serve to connect the cylinders
+together. The whole construction turns out very neat and light. The
+cylinder walls are 4 mm. or 3/16" thick and the combustion chamber is of
+cylindrical pancake form and is 140 mm. or 5.60 inch in diameter. The
+valve seats are 68 mm. in diameter and the valve port is 62 mm. in
+diameter.
+
+The passage joining the port is 57 mm. in diameter. In order to insert
+the valves into the cylinder the valve stem is made with two diameters
+and the valve has to be cocked to insert it in the guide, which has a
+bronze bushing at its upper end to compensate for the smaller valve stem
+diameter. The valve stem is 14 mm. or 9/16" in diameter and is reduced
+at its upper portion to 9-1/2 mm. The valves are operated through a push
+rod and rocker arm construction, which is 7/16" and exceedingly light.
+Rocker arm supports are steel studs with enlarged heads to take a double
+row ball bearing. A roller is mounted at one end of the rocker arm to
+impinge on the end of the valve stem, and the rocker arm has an
+adjustable globe stud at the other end. The push rods are light steel
+tubes with a wall thickness of 0.75 mm. and have a hardened steel cup at
+their upper end to engage the rocker arm globe stud and a hardened steel
+globe at their lower end to socket in the roller plunger.
+
+The Benz cam-shaft has a diameter of 26 mm. and is bored straight
+through 18 mm. and there is a spiral gear made integrally with the shaft
+in about the center of its length for driving the oil pump gear. The cam
+faces are 10 mm. wide. There is also, in addition to the intake and
+exhaust cams, a set of half compression cams. The shaft is moved
+longitudinally in its bearings by means of an eccentric to put these
+cams into action. At the fore end of the shaft is a driving gear flange
+which is very small in diameter and very thin. The flange is 68 mm. in
+diameter and 4 mm. thick and is tapped to take 6 mm. bolts. The total
+length of cam-shaft is 1038 mm., and it becomes a regular gun boring job
+to drill a hole of this length.
+
+The cam-shaft gear is 140 mm. or 5-1/2 inches outside diameter. It has
+fifty-four teeth and the gear face is 15 mm. or 19/32". The flange and
+web have an average thickness of 4 mm. or 5/32" and the web is drilled
+full of holes interposed between the spur gear mounted on the cam-shaft
+and the cam-shaft gear. There is a gear which serves to drive the
+magnetos and tachometer, also the air pump. The shaft is made integrally
+with this gear and has an eccentric portion against which the air pump
+roll plunger impinges.
+
+The seven-bearing crank-shaft is finished all over in a beautiful
+manner, and the shaft out of the particular motor we have shows no signs
+of wear whatever. The crank-pins are 55 mm. in diameter and 69 mm. long.
+Through both the crank-pin and main bearings there is drilled a 28 mm.
+hole, and the crank cheeks are plugged with solder. The crank cheeks are
+also built to convey the lubricant to the crank-pins. At the fore end of
+the crank cheek there is pressed on a spur driving gear. There is
+screwed on to the front end of the shaft a piece which forms a bevel
+water pump driving gear and the starting dog. At the rear end of the
+shaft very close to the propeller hub mounting there is a double thrust
+bearing to take the propeller thrust.
+
+Long, shouldered studs are screwed into the top half of the crank-case
+portion of the case and pass clean through the bottom half of the case.
+The case is very stiff and well ribbed. The three center bearing
+diaphragms have double walls. The center one serves as a duct through
+which water pipe passes, and those on either side of the center form the
+carburetor intake air passages and are enlarged in section at one side
+to take the carburetor barrel throttle.
+
+The pistons are of cast iron and carry three concentric rings 1/4 inch
+wide on their upper end, which are pinned at the joint. The top of the
+piston forms the frustum of the cone and the pistons are 110 mm. in
+length. The lower portion of the skirt is machined inside and has a wall
+thickness of 1 mm. Riveted to the piston head is a conical diaphragm
+which contacts with the piston pin when in place and serves to carry the
+heat off the center of the piston.
+
+The oil pump assembly comprises a pair of plunger pumps which draw oil
+from a separate outside pump, and constructed integrally with it is a
+gear pump which delivers the oil under about 60 pound pressure through a
+set of copper pipes in the base to the main bearings. The plunger oil
+pump shows great refinement of detail. A worm wheel and two eccentrics
+are machined up out of one piece and serve to operate the plungers.
+
+[Illustration: Fig. 246.--Part Sectional Side View and Sectional End
+View of Benz 160 Horse-Power Aviation Engine.]
+
+Some interesting details of the 160 horse-power Benz motor, which is
+shown at Fig. 246, are reproduced from the "Aerial Age Weekly," and show
+how carefully the design has been considered.
+
+  Maximum horse-power, 167.5 B. H. P.
+  Speed at maximum horse-power, 1,500 R. P. M.
+  Piston speed at maximum horse-power, 1,770 ft. per minute.
+  Normal horse-power, 160 B. H. P.
+  Speed at normal horse-power, 1,400 R. P. M.
+  Piston speed at normal horse-power, 1,656 ft. per minute.
+  Brake mean pressure at maximum horse-power, 101.2 pound per square
+  inch.
+  Brake mean pressure at normal horse-power, 103.4 pound per square
+  inch.
+  Specific power cubic inch swept volume per B. H. P., 5.46 cubic inch;
+  160 B. H. P.
+  Weight of piston, complete with gudgeon pin, rings, etc., 5.0 pound.
+  Weight of connecting rod, complete with bearings, 4.99 pound; 1.8
+  pound reciprocating.
+  Weight of reciprocating parts per cylinder, 6.8 pound.
+  Weight of reciprocating parts per square inch of piston area, 0.33
+  pound.
+  Outside diameter of inlet valve, 68 mm.; 2.68 inches.
+  Diameter of inlet valve port (_d_), 61.5 mm.; 2.42 inches.
+  Maximum lift of inlet valve (_h_), 11 mm.; 0.443 inch.
+  Area of inlet valve opening ([pi] _d_ _h_), 21.25 square cm.; 3.29
+  square inches.
+  Inlet valve opens, degrees on crank, top dead center.
+  Inlet valve closes, degrees on crank, 60° late; 35 mm. late.
+  Outside diameter of exhaust valve, 68 mm.; 2.68 inches.
+  Diameter of exhaust valve port (_d_), 61.5 mm.; 2.42 inches.
+  Maximum lift of exhaust valve (_h_) 11 mm.; 0.433 inch.
+  Area of exhaust valve opening ([pi] _d_ _h_), 21.25 square cm.; 3.29
+  square inches.
+  Exhaust valve opens, degrees on crank, 60° early; 35 mm. early.
+  Exhaust valve closes, degrees on crank, 16-1/2° late; 5 mm. late.
+  Length of connecting rod between centers, 314 mm.; 12.36 inches.
+  Ratio connecting rod to crank throw, 3.49:1.
+  Diameter of crank-shaft, 55 mm. outside, 2.165 inches; 28 mm. inside,
+  1.102 inches.
+  Diameter of crank-pin, 55 mm. outside, 2.165 inches; 28 mm. inside,
+  1.102 inches.
+  Diameter of gudgeon pin, 30 mm. outside, 1.181 inches; 19 mm. inside,
+  0.708 inch.
+  Diameter of cam-shaft, 26 mm. outside, 1.023 inches; 18 mm. inside,
+  0.708 inch.
+  Number of crank-shaft bearings, 7.
+  Projected area of crank-pin bearings, 36.85 square cm.; 5.72 square
+  inches.
+  Projected area of gudgeon pin bearings, 22.20 square cm.; 3.44 square
+  inches.
+  Firing sequence, 1, 5, 3, 6, 2, 4.
+  Type of magnetos, ZH6 Bosch.
+  Direction of rotation of magneto from driving end, one clock, one
+  anti-clock.
+  Magneto timing, full advance, 30° early (16 mm. early).
+  Type of carburetors (2) Benz design.
+  Fuel consumption per hour, normal horse-power, 0.57 pint.
+  Normal speed of propeller, engine speed, 1,400 R. P. M.
+
+
+AUSTRO-DAIMLER ENGINE
+
+One of the first very successful European flying engines which was
+developed in Europe is the Austro-Daimler, which is shown in end section
+in a preceding chapter. The first of these motors had four-cylinders,
+120 by 140 millimeters, bore and stroke, with cast iron cylinders,
+overhead valves operated by means of a single rocker arm, controlled by
+two cams and the valves were closed by a single leaf spring which
+oscillates with the rocker arm. The cylinders are cast singly and have
+either copper or steel jackets applied to them. The four-cylinder design
+was afterwards expanded to the six-cylinder design and still later a
+six-cylinder motor of 130 by 175 millimeters was developed. This motor
+uses an offset crank-shaft, as does the Benz motor, and the effect of
+offset has been discussed earlier on in this treatise. The Benz motor
+also uses an offset cam-shaft which improves the valve operation and
+changes the valve lift diagram. The lubrication also is different than
+any other aviation motor, since individual high pressure metering pumps
+are used to deliver fresh oil only to the bearings and cylinders, as was
+the custom in automobile practice some ten years ago.
+
+
+SUNBEAM AVIATION ENGINES
+
+These very successful engines have been developed by Louis Coatalen. At
+the opening of the war the largest sized Coatalen motor was 225
+horse-power and was of the L-head type having a single cam-shaft for
+operating valves and was an evolution from the twelve-cylinder racing
+car which the Sunbeam Company had previously built. Since 1914 the
+Sunbeam Company have produced engines of six-, eight-, twelve- and
+eighteen-cylinders from 150 to 500 horse-power with both iron and
+aluminum cylinders. For the last two years all the motors have had
+overhead cam-shafts with a separate shaft for operating the intake and
+exhaust valves. Cam-shafts are connected through to the crank-shaft by
+means of a train of spur gears, all of which are mounted on two double
+row ball bearings. In the twin six, 350 horse-power engine, operating at
+2100 R. P. M., requires about 4 horse-power to operate the cam-shafts.
+This motor gives 362 horse-power at 2100 revolutions and has a fuel
+consumption of 51/100 of a pint per brake horse-power hour. The
+cylinders are 110 by 160 millimeters. The same design has been expanded
+into an eighteen-cylinder which gives 525 horse-power at 2100 turns.
+There has also been developed a very successful eight-cylinder motor
+rated at 2220 horse-power which has a bore and stroke of 120 by 130
+millimeters, weight 450 pounds. This motor is an aluminum block
+construction with steel sleeves inserted. Three valves are operated, one
+for the inlet and two for the exhaust. One cam-shaft operates the three
+valves.
+
+[Illustration: Fig. 247.--At Top, the Sunbeam Overhead Valve 170
+Horse-Power Six-Cylinder Engine. Below, Side View of Sunbeam 350
+Horse-Power Twelve-Cylinder Vee Engine.]
+
+The modern Sunbeam engines operate with a mean effective pressure of 135
+pounds with a compression ratio of 6 to 1 sea level. The connecting rods
+are of the articulated type as in the Renault motor and are very short.
+The weight of these motors turns out at 2.6 pounds per brake
+horse-power, and they are able to go through a 100 hour test without any
+trouble of any kind. The lubricating system comprises a dry base and oil
+pump for drawing the oil off from the base, whence it is delivered to
+the filter and cooling system. It then is pumped by a separate high
+pressure gear pump through the entire motor. In these larger European
+motors, castor-oil is used largely for lubrication. It is said that
+without the use of castor-oil it is impossible to hold full power for
+five hours. Coatalen favors aluminum cylinders rather than cast iron.
+The series of views in Figs. 247 to 250 inclusive, illustrates the
+vertical, narrow type of engine; the V-form; and the broad arrow type
+wherein three rows, each of six-cylinders, are set on a common
+crank-case. In this water-cooled series the gasoline and oil consumption
+are notably low, as is the weight per horse-power.
+
+[Illustration: Fig. 248.--Side View of Eighteen-Cylinder Sunbeam
+Coatalen Aircraft Engine Rated at 475 B.H.P.]
+
+[Illustration: Fig. 249.--Sunbeam Eighteen-Cylinder Motor, Viewed from
+Pump and Magneto End.]
+
+In the eighteen-cylinder overhead valve Sunbeam-Coatalen aircraft engine
+of 475 brake horse-power, there are no fewer than half a dozen magnetos.
+Each magneto is inclosed. Two sparks are furnished to each cylinder
+from independent magnetos. On this engine there are also no fewer than
+six carburetors. Shortness of crank-shaft, and therefore of engine
+length, and absence of vibration are achieved by the linking of the
+connecting-rods. Those concerned with three-cylinders in the broad arrow
+formation work on one crank-pin, the outer rods being linked to the
+central master one. In consequence of this arrangement, the piston
+travel in the case of the central row of cylinders is 160 mm., while the
+stroke of the pistons of the cylinders set on either side is in each
+case 168 mm. Inasmuch as each set of six-cylinders is completely
+balanced in itself, this difference in stroke does not affect the
+balance of the engine as a whole. The duplicate ignition scheme also
+applies to the twelve-cylinder 350 brake horse-power Sunbeam-Coatalen
+overhead valve aircraft engine type. It is distinguishable,
+incidentally, by the passage formed through the center of each induction
+pipe for the sparking plug in the center cylinder of each block of
+three. In this, as in the eighteen-cylinder and the six-cylinder types,
+there are two cam-shafts for each set of cylinders. These cam-shafts are
+lubricated by low pressure and are operated through a train of inclosed
+spur wheels at the magneto end of the machine. The six-cylinder, 170
+brake horse-power vertical type employs the same general principles,
+including the detail that each carburetor serves gas to a group of
+three-cylinders only. It will be observed that this engine presents
+notably little head resistance, being suitable for multi-engined
+aircraft.
+
+[Illustration: Fig. 250.--Propeller End of Sunbeam Eighteen-Cylinder 475
+B.H.P. Aviation Engine.]
+
+
+INDICATING METERS FOR AUXILIARY SYSTEMS
+
+[Illustration: Fig. 251.--View of Airplane Cowl Board, Showing the
+Various Navigating and Indicating Instruments to Aid the Aviator in
+Flight.]
+
+The proper functioning of the power plant and the various groups
+comprising it may be readily ascertained at any time by the pilot
+because various indicating meters and pressure gauges are provided which
+are located on a dash or cowl board in front of the aviator, as shown at
+Fig. 251. The speed indicator corresponds to the speedometer of an
+automobile and gives an indication of the speed the airplane is making,
+which taken in conjunction with the clock will make it possible to
+determine the distance covered at a flight. The altimeter, which is an
+aneroid barometer, outlines with fair accuracy the height above the
+ground at which a plane is flying. These instruments are furnished to
+enable the aviator to navigate the airplane when in the air, and if the
+machine is to be used for cross-country flying, they may be supplemented
+by a compass and a drift set. It will be evident that these are purely
+navigating instruments and only indicate the motor condition in an
+indirect manner. The best way of keeping track of the motor action is to
+watch the tachometer or revolution counter which is driven from the
+engine by a flexible shaft. This indicates directly the number of
+revolutions the engine is making per minute and, of course, any slowing
+up of the engine in normal flights indicates that something is not
+functioning as it should. The tachometer operates on the same principle
+as the speed indicating device or speedometer used in automobiles except
+that the dial is calibrated to show revolutions per minute instead of
+miles per hour. At the extreme right of the dash at Fig. 251 the spark
+advance and throttle control levers are placed. These, of course,
+regulate the motor speed just as they do in an automobile. Next to the
+engine speed regulating levers is placed a push button cut-out switch to
+cut out the ignition and stop the motor. Three pressure gauges are
+placed in a line. The one at the extreme right indicates the pressure of
+air on the fuel when a pressure feed system is used. The middle one
+shows oil pressure, while that nearest the center of the dash board is
+employed to show the air pressure available in the air starting system.
+It will be evident that the character of the indicating instruments will
+vary with the design of the airplane. If it was provided with an
+electrical starter instead of an air system electrical indicating
+instruments would have to be provided.
+
+
+COMPRESSED AIR-STARTING SYSTEMS
+
+Two forms of air-starting systems are in general use, one in which the
+crank-shaft is turned by means of an air motor, the other class where
+compressed air is admitted to the cylinders proper and the motor turned
+over because of the air pressure acting on the engine pistons. A system
+known as the "Never-Miss" utilizes a small double-cylinder air pump is
+driven from the engine by means of suitable gearing and supplies air to
+a substantial container located at some convenient point in the
+fuselage. The air is piped from the container to a dash-control valve
+and from this member to a peculiar form of air motor mounted near the
+crank-shaft. The air motor consists of a piston to which a rack is
+fastened which engages a gear mounted on the crank shaft provided with
+some form of ratchet clutch to permit it to revolve only in one
+direction, and then only when the gear is turning faster than the engine
+crank-shaft.
+
+The method of operation is extremely simple, the dash-control valve
+admitting air from the supply tank to the top of the pump cylinder. When
+in the position shown in cut the air pressure will force the piston and
+rack down and set the engine in motion. A variety of air motors are used
+and in some the pump and motor may be the same device, means being
+provided to change the pump to an air motor when the engine is to be
+turned over.
+
+The "Christensen" air starting system is shown at Figs. 252 and 253. An
+air pump is driven by the engine, and this supplies air to an air
+reservoir or container attached to the fuselage. This container
+communicates with the top of an air distributor when a suitable control
+valve is open. An air pressure gauge is provided to enable one to
+ascertain the air pressure available. The top of each cylinder is
+provided with a check valve, through which air can flow only in one
+direction, i.e., from the tank to the interior of the cylinder. Under
+explosive pressure these check valves close. The function of the
+distributor is practically the same as that of an ignition timer, its
+purpose being to distribute the air to the cylinders of the engine only
+in the proper firing order. All the while that the engine is running and
+the car is in motion the air pump is functioning, unless thrown out of
+action by an easily manipulated automatic control. When it is desired to
+start the engine a starting valve is opened which permits the air to
+flow to the top of the distributor, and then through a pipe to the check
+valve on top of the cylinder about to explode. As the air is going
+through under considerable pressure it will move the piston down just as
+the explosion would, and start the engine rotating. The inside of the
+distributor rotates and directs a charge of air to the cylinder next to
+fire. In this way the engine is given a number of revolutions, and
+finally a charge of gas will be ignited and the engine start off on its
+cycle of operation. To make starting positive and easier some gasoline
+is injected in with the air so an inflammable mixture is present in the
+cylinders instead of air only. This ignites easily and the engine starts
+off sooner than would otherwise be the case. The air pressure required
+varies from 125 to 250 pounds per square inch, depending upon the size
+and type of the engine to be set in motion.
+
+[Illustration: Fig. 252.--Parts of Christensen Air Starting System Shown
+at A, and Application of Piping and Check Valves to Cylinders of
+Thomas-Morse Aeromotor Outlined at B.]
+
+[Illustration: Fig. 253.--Diagrams Showing Installation of Air Starting
+System on Thomas-Morse Aviation Motor.]
+
+
+ELECTRIC STARTING SYSTEMS
+
+Starters utilizing electric motors to turn over the engine have been
+recently developed, and when properly made and maintained in an
+efficient condition they answer all the requirements of an ideal
+starting device. The capacity is very high, as the motor may draw
+current from a storage battery and keep the engine turning over for
+considerable time on a charge. The objection against their use is that
+it requires considerable complicated and costly apparatus which is
+difficult to understand and which requires the services of an expert
+electrician to repair should it get out of order, though if battery
+ignition is used the generator takes the place of the usual ignition
+magneto.
+
+In the Delco system the electric current is generated by a combined
+motor-generator permanently geared to the engine. When the motor is
+running it turns the armature and the motor generator is acting as a
+dynamo, only supplying current to a storage battery. On account of the
+varying speeds of the generator, which are due to the fluctuation in
+engine speed, some form of automatic switch which will disconnect the
+generator from the battery at such times that the motor speed is not
+sufficiently high to generate a current stronger than that delivered by
+the battery is needed. These automatic switches are the only delicate
+part of the entire apparatus, and while they require very delicate
+adjustment they seem to perform very satisfactorily in practice.
+
+When it is desired to start the engine an electrical connection is
+established between the storage battery and the motor-generator unit,
+and this acts as a motor and turns the engine over by suitable gearing
+which engages the gear teeth cut into a special gear or disc attached to
+the engine crank-shaft. When the motor-generator furnishes current for
+ignition as well as for starting the motor, the fact that the current
+can be used for this work as well as starting justifies to a certain
+extent the rather complicated mechanism which forms a complete starting
+and ignition system, and which may also be used for lighting if
+necessary in night flying.
+
+An electric generator and motor do not complete a self-starting system,
+because some reservoir or container for electric current must be
+provided. The current from the generator is usually stored in a storage
+battery from which it can be made to return to the motor or to the same
+armature that produced it. The fundamental units of a self-starting
+system, therefore, are a generator to produce the electricity, a storage
+battery to serve as a reservoir, and an electric motor to rotate the
+motor crank-shaft. Generators are usually driven by enclosed gearing,
+though silent chains are used where the center distance between the
+motor shaft and generator shaft is too great for the gears. An electric
+starter may be directly connected to the gasoline engine, as is the case
+where the combined motor-generator replaces the fly-wheel in an
+automobile engine. The motor may also drive the engine by means of a
+silent chain or by direct gear reduction.
+
+Every electric starter must use a switch of some kind for starting
+purposes and most systems include an output regulator and a reverse
+current cut-out. The output regulator is a simple device that regulates
+the strength of the generator current that is supplied the storage
+battery. A reverse current cut-out is a form of check valve that
+prevents the storage battery from discharging through the generator.
+Brief mention is made of electric starting because such systems will
+undoubtedly be incorporated in some future airplane designs. Battery
+ignition is already being experimented with.
+
+
+BATTERY IGNITION SYSTEM PARTS
+
+A battery ignition system in its simplest form consists of a current
+producer, usually a set of dry cells or a storage battery, an induction
+coil to transform the low tension current to one having sufficient
+strength to jump the air gap at the spark-plug, an igniter member
+placed in the combustion chamber and a timer or mechanical switch
+operated by the engine so that the circuit will be closed only when it
+is desired to have a spark take place in the cylinders. Battery ignition
+systems may be of two forms, those in which the battery current is
+stepped up or intensified to enable it to jump an air gap between the
+points of the spark plug, these being called "high tension" systems and
+the low tension form (never used on airplane motors) in which the
+battery current is not intensified to a great degree and a spark
+produced in the cylinder by the action of a mechanical circuit breaker
+in the combustion chamber. The low tension system is the simplest
+electrically but the more complex mechanically. The high tension system
+has the fewest moving parts but numerous electrical devices. At the
+present time all airplane engines use high tension ignition systems, the
+magneto being the most popular at the present time. The current
+distribution and timing devices used with modern battery systems are
+practically the same as similar parts of a magneto.
+
+
+
+
+INDEX
+
+
+                                                          PAGE
+
+  A
+
+  Action of Four-cycle Engine                               38
+  Action of Le Rhone Rotary Engine                         503
+  Action of Two-cycle Engine                                41
+  Action of Vacuum Feed System                             119
+  Actual Duration of Different Functions                    93
+  Actual Heat Efficiency                                    62
+  Adiabatic Diagram                                         51
+  Adiabatic Law                                             50
+  Adjustment of Bearings                                   449
+  Adjustment of Carburetors                                151
+  Aerial Motors, Must be Light                              20
+  Aerial Motors, Operating Conditions of                    19
+  Aerial Motors, Requirements of                            19
+  Aeromarine Six-cylinder Engine                           527
+  Aeronautics, Division in Branches                         18
+  Aerostatics                                               18
+  Air-cooled Engine Design                                 229
+  Air-cooling Advantages                                   231
+  Air-cooling, Direct Method                               228
+  Air-cooling Disadvantages                                231
+  Air-cooling Systems                                      223
+  Aircraft, Heavier Than Air                                17
+  Aircraft, Lighter Than Air                                18
+  Aircraft Types, Brief Consideration of                    17
+  Air Needed to Burn Gasoline                              113
+  Airplane Engine, Power Needed                             21
+  Airplane Engines, Overhauling                            412
+  Airplane Engine, How to Time                             269
+  Airplane Engine Lubrication                              209
+  Airplane, How Supported                                   21
+  Airplane Motors, German                                  543
+  Airplane Motor Types                                      20
+  Airplane Motors, Weight of                                21
+  Airplane Power Plant Installation                        324
+  Airplane Types                                            18
+  Airplanes, Horse-power Used in                            26
+  Air Pressure Diminution, With Altitude                   144
+  Altitude, How it Affects Mixture                         153
+  Aluminum, Use in Pistons                                 297
+  American Aviation Engines, Statistics                    546
+  Anzani Radial Engine Installation                        344
+  Anzani Six-cylinder Star Engine                          465
+  Anzani Six-cylinder Water-cooled Engine                  459
+  Anzani Ten- and Twenty-cylinder Engines                  468
+  Anzani Three-cylinder Engine                             459
+  Anzani Three-cylinder Y Type                             462
+  Argus Engine Construction                                545
+  Armature Windings                                        168
+  Atmospheric Conditions, Compensating For                 143
+  Austro-Daimler Engine                                    557
+  Aviatics                                                  18
+  Aviation Engine, Aeromarine                              527
+  Aviation Engine, Anzani Six-cylinder Star                465
+  Aviation Engine, Canton and Unné                         469
+  Aviation Engine Cooling                                  219
+  Aviation Engine, Curtiss                                 519
+  Aviation Engine Cylinders                                233
+  Aviation Engine, Early Gnome                             472
+  Aviation Engine, German Gnome Type                       495
+  Aviation Engine, Gnome Monosoupape                       486
+  Aviation Engine, How To Dismantle                        415
+  Aviation Engine, How to Start                            460
+  Aviation Engine, Le Rhone Rotary                         495
+  Aviation Engine Oiling                                   218
+  Aviation Engine Parts, Functions of                       82
+  Aviation Engine, Renault Air-cooled                      507
+  Aviation Engine, Stand for Supporting                    414
+  Aviation Engine, Sturtevant                              515
+  Aviation Engine, Thomas-Morse                            521
+  Aviation Engine Types                                    457
+  Aviation Engine, Wisconsin                               531
+  Aviation Engines, Anzani Six-cylinder Water-cooled       459
+  Aviation Engines, Anzani Ten- and Twenty-cylinder        468
+  Aviation Engines, Anzani Three-cylinder                  459
+  Aviation Engines, Anzani Y Type                          462
+  Aviation Engines, Argus                                  545
+  Aviation Engines, Austro-Daimler                         557
+  Aviation Engines, Benz                                   551
+  Aviation Engines, Four- and Six-cylinder                  88
+  Aviation Engines, German                                 543
+  Aviation Engines, Hall-Scott                             539
+  Aviation Engines, Hispano-Suiza                          512
+  Aviation Engines, Mercedes                               543
+  Aviation Engines, Overhauling                            412
+  Aviation Engines, Principal Parts of                      80
+  Aviation Engines, Starting Systems For                   567
+  Aviation Engines, Sunbeam                                558
+
+  B
+
+  Balanced Crank-shafts                                    318
+  Ball-bearing Crank-shafts                                319
+  Battery Ignition Systems                                 571
+  Baverey Compound Nozzle                                  137
+  Bearings, Adjustment of                                  449
+  Bearing Alignment                                        453
+  Bearing Brasses, Fitting                                 450
+  Bearing Parallelism, Testing                             453
+  Bearing Scrapers and Their Use                           446
+  Benz Aviation Engines                                    551
+  Benz Engine Statistics                                   551
+  Berling Magneto                                          174
+  Berling Magneto, Adjustment of                           180
+  Berling Magneto Care                                     180
+  Berling Magneto Circuits                                 176
+  Berling Magneto, Setting                                 178
+  Block Castings                                           234
+  Blowing Back                                             269
+  Bolts, Screwing Down                                     452
+  Bore and Stroke Ratio                                    240
+  Boyle's Law                                               49
+  Brayton Engine                                            48
+  Breaker Box, Adjustment of                               180
+  Breast and Hand Drills                                   387
+  Burning Out Carbon Deposits                              421
+  Bushings, Cam-shaft, Wear in                             456
+
+  C
+
+  Calipers, Inside and Outside                             398
+  Cam Followers, Types of                                  260
+  Cams for Valve Actuation                                 259
+  Cam-shaft Bushings                                       456
+  Cam-shaft Design                                         313
+  Cam-shaft Drive Methods                                  261
+  Cam-shaft Testing                                        451
+  Cam-shafts and Timing Gears                              456
+  Canton and Unné Engine                                   469
+  Carbon, Burning out with Oxygen                          421
+  Carbon Deposits, Cause of                                418
+  Carbon Removal                                           419
+  Carbon Scrapers, How Used                                420
+  Carburetion Principles                                   112
+  Carburetion System Troubles                              355
+  Carburetor, Claudel                                      127
+  Carburetor, Compound Nozzle Zenith                       135
+  Carburetor, Concentric Float and Jet Type                125
+  Carburetor, Duplex Zenith                                138
+  Carburetor, Duplex Zenith, Trouble in                    357
+  Carburetor Installation, In Airplanes                    148
+  Carburetor, Le Rhone                                     501
+  Carburetor, Master Multiple Jet                          133
+  Carburetor, Schebler                                     125
+  Carburetor Troubles, How to Locate                       354
+  Carburetor, Two Stage                                    131
+  Carburetor, What it Should Do                            114
+  Carburetors, Float Feed                                  122
+  Carburetors, Multiple Nozzle                             130
+  Carburetors, Notes on Adjustment                         151
+  Carburetors, Reversing Position of                       149
+  Carburetors, Spraying                                    120
+  Care of Dixie Magneto                                    188
+  Castor Oil, for Cylinder Lubrication                     205
+  Castor Oil, Why Used In Gnome Engines                    211
+  Center Gauge                                             403
+  Chisels, Forms of                                        384
+  Christensen Air Starting System                          567
+  Circuits, Magnetic                                       161
+  Classification of Engines                                458
+  Claudel Carburetor                                       127
+  Cleaning Distributor                                     180
+  Clearances Between Valve Stem and Actuators              261
+  Combustion Chamber Design                                239
+  Combustion Chambers, Spherical                            76
+  Common Tools, Outfit of                                  378
+  Comparing Two-cycle and Four-cycle Types                  44
+  Compound Cam Followers                                   260
+  Compound Piston Rings                                    301
+  Compressed Air Starting System                           565
+  Compression, Factors Limiting                             69
+  Compression, in Explosive Motors, Value of                68
+  Compression Pressures, Chart for                          72
+  Compression Temperature                                   71
+  Computations for Horse-power Needed                       25
+  Computations for Temperature                              52
+  Concentric Piston Ring                                   299
+  Concentric Valves                                        255
+  Connecting Rod Alignment, Testing                        454
+  Connecting Rod, Conventional                             308
+  Connecting Rod Forms                                     305
+  Connecting Rod, Gnome Engine                             305
+  Connecting Rods, Fitting                                 449
+  Connecting Rods for Vee Engines                          310
+  Connecting Rods, Le Rhone                                498
+  Connecting Rods, Master                                  310
+  Constant Level Splash System                             215
+  Construction of Dixie Magneto                            186
+  Construction of Pistons                                  288
+  Conversion of Heat to Power                               58
+  Cooling by Air                                           223
+  Cooling by Positive Water Circulation                    224
+  Cooling, Heat Loss in                                     66
+  Cooling System Defects                                   358
+  Cooling Systems Used                                     223
+  Cooling Systems, Why Needed                              219
+  Cotter Pin Pliers                                        384
+  Crank-case, Conventional                                 320
+  Crank-case Forms                                         320
+  Crank-case, Gnome                                        323
+  Crank-shaft, Built Up                                    315
+  Crank-shaft Construction                                 315
+  Crank-shaft Design                                       315
+  Crank-shaft Equalizer                                    449
+  Crank-shaft Form                                         315
+  Crank-shaft, Gnome Engine                                483
+  Crank-shafts, Balanced                                   318
+  Crank-shafts, Ball Bearing                               319
+  Cross Level                                              403
+  Crude Petroleum, Distillates of                          111
+  Curtiss Aviation Engines                                 519
+  Curtiss Engine Installation                              328
+  Curtiss Engine Repairing Tools                           408
+  Cutting Oil Grooves                                      448
+  Cylinder Blocks, Advantages of                           237
+  Cylinder Block, Duesenberg                               235
+  Cylinder Castings, Individual                            234
+  Cylinder Construction                                    233
+  Cylinder Faults and Correction                           416
+  Cylinder Form and Crank-shaft Design                     238
+  Cylinder Head Packings                                   417
+  Cylinder Head, Removable                                 239
+  Cylinder, I Head Form                                    248
+  Cylinder, L Head Form                                    248
+  Cylinder Oils                                            206
+  Cylinder Placing                                          20
+  Cylinder Placing in V Motor                               99
+  Cylinder Retention, Gnome                                475
+  Cylinder, T Head Form                                    248
+  Cylinders, Cast in Blocks                                235
+  Cylinders, Odd Number in Rotary Engines                  482
+  Cylinders, Repairing Scored                              423
+  Cylinders, Valve Location in                             245
+
+  D
+
+  Defects in Cylinders                                     417
+  Defects in Dry Battery                                   373
+  Defects in Fuel System                                   354
+  Defects in Induction Coil                                373
+  Defects in Magneto                                       372
+  Defects in Storage Battery                               372
+  Defects in Timer                                         373
+  Defects in Wiring and Remedies                           373
+  Die Holder                                               394
+  Dies for Thread Cutting                                  395
+  Diesel Motor Cards                                        67
+  Diesel System                                            144
+  Direct Air Cooling                                       228
+  Dirigible Balloons                                        18
+  Dismantling Airplane Engine                              415
+  Distillates of Crude Petroleum                           111
+  Division of Circle in Degrees                            268
+  Dixie Ignition Magneto                                   184
+  Dixie Magneto, Care of                                   188
+  Draining Oil From Crank-case                             214
+  Drilling Machines                                        386
+  Drills, Types and Use                                    388
+  Driving Cam-shaft, Methods of                            262
+  Dry Cell Battery, Defects in                             373
+  Duesenberg Sixteen Valve Engine                          525
+  Duesenberg Valve Action                                  255
+  Duplex Zenith Carburetor                                 138
+
+  E
+
+  Early Gnome Motor, Construction of                       472
+  Early Ignition Systems                                   155
+  Early Types of Gas Engine                                 28
+  Early Vaporizer Forms                                    120
+  Eccentric Piston Ring                                    299
+  Economy, Factors Governing                                64
+  Efficiency, Actual Heat                                   62
+  Efficiency, Maximum Theoretical                           61
+  Efficiency, Mechanical                                    62
+  Efficiency of Internal Combustion Engine                  60
+  Efficiency, Various Measures of                           61
+  Eight-cylinder Engine                                     95
+  Eight-cylinder Timing Diagram                            276
+  Electricity and Magnetism, Relation of                   162
+  Electrical Ignition Best                                 156
+  Electric Starting Systems                                569
+  Engine, Advantages of V Type                              95
+  Engine Base Construction                                 319
+  Engine Bearings, Adjusting                               443
+  Engine Bearings, Refitting                               442
+  Engine Bed Timbers, Standard                             330
+  Engine, Four-cycle, Action of                             38
+  Engine, Four-cycle, Piston Movements in                   40
+  Engine Functions, Duration of                             93
+  Engine Ignition, Locating Troubles                       353
+  Engine Installation, Gnome                               344
+  Engine Installation, Anzani Radial                       344
+  Engine Installation, Hall-Scott                          332
+  Engine Installation, Rotary                              342
+  Engine Operation, Sequence of                             84
+  Engine Parts and Functions                                80
+  Engine Starts Hard, Ignition Troubles Causing            369
+  Engine Stoppage, Causes of                               347
+  Engine Temperatures                                      221
+  Engine Trouble Charts                                    369
+  Engine Troubles, Cooling                                 358
+  Engine Troubles, Hints For Locating                      345
+  Engine Troubles, Ignition                                353
+  Engine Troubles, Noisy Operation                         359
+  Engine Troubles, Oiling                                  357
+  Engine Troubles Summarized                               350
+  Engine, Two-cycle, Action of                              41
+  Engines, Classification of                               458
+  Engines, Cylinder Arrangement                          31-32
+  Engines, Eight-cylinder V                                 95
+  Engines, Four-cylinder Forms                              88
+  Engines, Graphic Comparison of                      33-34-35
+  Engines, Internal Combustion, Types of                    30
+  Engines, Multiple Cylinder, Power Delivery in             91
+  Engines, Multiple Cylinder, Why Best                      83
+  Engines, Rotary Cylinder                                 107
+  Engines, Six-cylinder Forms                               88
+  Engines, Twelve-cylinder                                  96
+  Equalizer, Crank-shaft                                   449
+  Exhaust Closing                                          270
+  Exhaust Valve Design, Early Gnome                        475
+  Exhaust Valve Opening                                    270
+  Explosive Gases, Mixtures of                              56
+  Explosive Motors, Inefficiency in                         74
+  Explosive Motors, Why Best                                27
+
+  F
+
+  Factors Governing Economy                                 64
+  Factors Limiting Compression                              70
+  Faults in Ignition                                       352
+  Figuring Horse-power Needed                               21
+  Files, Use and Care of                                   383
+  First Law of Gases                                        49
+  Fitting Bearings By Scraping                             447
+  Fitting Brasses                                          450
+  Fitting Connecting Rods                                  449
+  Fitting Main Bearings                                    448
+  Fitting Piston Rings                                     439
+  Float Feed Carburetor Development                        124
+  Float Feed Carburetors                                   122
+  Force Feed Oiling System                                 218
+  Forked Connecting Rods                                   310
+  Four-cycle Engine, Action of                              38
+  Four-cycle Engine, Why Best                               45
+  Fourteen-cylinder Engine                                 474
+  Four Valves Per Cylinder                                 284
+  Friction, Definition of                                  302
+  Fuel Feed By Gravity                                     116
+  Fuel Feed by Vacuum Tank                                 117
+  Fuel Storage and Supply                                  116
+  Fuel Strainers, Types of                                 141
+  Fuel Strainers, Utility of                               140
+  Fuel System Faults                                       354
+  Fuel System Installation, Hall-Scott                     336
+  Fuel System, Gnome                                       490
+  Fuel Utilization Chart                                    62
+
+  G
+
+  Gas Engine, Beau de Rocha's Principles                    59
+  Gas Engine Development                                    28
+  Gas Engine, Early Forms of                                48
+  Gas Engine, Inventors of                                  29
+  Gas Engine, Theory of                                     47
+  Gases, Compression of                                     49
+  Gases, First Law of                                       49
+  Gases, Second Law of                                      50
+  Gaskets, How to Use                                      452
+  Gasoline, Air Needed to Burn                             113
+  Gas Engines, Parts of                                     80
+  Gas Vacuum Engine, Brown's                                28
+  German Airplane Motors                                   543
+  German Gnome Type Engine                                 495
+  Gnome Aviation Engine, Early Form                        472
+  Gnome Crank-shaft                                        483
+  Gnome Cylinder, Machining                                489
+  Gnome Cylinder Retention                                 475
+  Gnome Engine, Fuel, Lubrication and Ignition             490
+  Gnome Engine, German Type                                495
+  Gnome Engine Installation                                344
+  Gnome Firing Order                                       482
+  Gnome Fourteen-cylinder, Engine                          474
+  Gnome Fourteen-cylinder Engine Details                   480
+  Gnome Monosoupape, How to Time                           278
+  Gnome Monosoupape Type Engine                            486
+  Graphic Comparison of Engine Types                  33-34-35
+  Graphic Comparison, Two- and Four-cycle                   46
+  Gravity Feed System                                      116
+  Grinding Valves                                          429
+
+  H
+
+  Hall-Scott Aviation Engines                              539
+  Hall-Scott Engine Installation                           332
+  Hall-Scott Engine, Preparations For Starting             341
+  Hall-Scott Engine Tools                                  410
+  Hall-Scott Lubrication System                            211
+  Hall-Scott Statistic Sheet                               544
+  Heat and Its Work                                         54
+  Heat in Gas Engine Cylinder                               69
+  Heat Given to Cooling Water                               78
+  Heat Loss, Causes of                                      74
+  Heat Loss in Airplane Engine                             221
+  Heat Loss in Wall Cooling                                 65
+  High Altitude, How it Affects Power                      144
+  High Tension Magneto                                     172
+  Hints For Locating Engine Troubles                       345
+  Hints for Starting Engine                                361
+  Hispano-Suiza Model A Engine                             512
+  Horse-power Needed in Airplane                            21
+  Horse-power Needed, How Figured                           22
+  How An Engine is Timed                                   277
+
+  I
+
+  Ignition, Electric                                       156
+  Ignition, Elements of                                    157
+  Ignition of Gnome Engine                                 490
+  Ignition System, Battery                                 571
+  Ignition Systems, Early                                  155
+  Ignition System Faults                                   352
+  Ignition, Time of                                        273
+  Ignition, Two Spark                                      196
+  I Head Cylinders                                         248
+  Improvements in Gas Engines                               29
+  Indicating Meters, Engine Speed                          563
+  Indicating Meters, Oil and Air Pressure                  563
+  Indicator Cards, How To Read                              66
+  Indicator Cards, Value of                                 66
+  Individual Cylinder Castings                             234
+  Induction Coil, Defects in                               373
+  Inefficiency, Causes of                                   74
+  Inlet Valve Closing                                      272
+  Inlet Valve Opening                                      270
+  Installation, Airplane Engine                            324
+  Installation, Curtiss OX-2 Engine                        328
+  Installation, Hall-Scott Engine                          332
+  Installation of Rotary Engines                           342
+  Intake Manifold Construction                             143
+  Intake Manifold Design                                   142
+  Internal Combustion Engine, Efficiency of             60, 62
+  Internal Combustion Engines, Main Types of                30
+  Inverted Engine Placing                                  325
+  Isothermal Diagram                                        51
+  Isothermal Law                                            48
+
+  K
+
+  Keeping Oil Out of Combustion Chamber                    303
+  Knight Sleeve Valves                                     266
+
+  L
+
+  Lag and Lead, Explanation of                             268
+  Lapping Crank-pins                                       445
+  Lead Given Exhaust Valve                                 270
+  Leak Proof Piston Rings                                  301
+  Lenoir Engine Action                                      48
+  Le Rhone Cams and Valve Actuation                        500
+  Le Rhone Carburetor                                      501
+  Le Rhone Connecting Rod Assembly, Distinctive            498
+  Le Rhone Engine Action                                   503
+  Le Rhone Rotary Engine                                   495
+  L Head Cylinders                                         248
+  Liquid Fuels, Properties of                              110
+  Locating Carburetor Troubles                             354
+  Locating Engine Troubles                                 350
+  Locating Ignition Troubles                               353
+  Locating Oiling Troubles                                 357
+  Location of Magneto Trouble                              181
+  Losses in Wall Cooling                                    65
+  Lost Power and Overheating, Summary of Troubles Causing  363
+  Lubricants, Derivation of                                204
+  Lubricants, Requirements of                              204
+  Lubricating System Classification                        208
+  Lubricating Systems, Selection of                        208
+  Lubrication By Constant Level Splash System              215
+  Lubrication By Dry Crank-case Method                     218
+  Lubrication By Force Feed Best                           218
+  Lubrication of Magneto                                   180
+  Lubrication System, Gnome                                490
+  Lubrication System, Hall-Scott                           211
+  Lubrication System, Thomas-Morse                         210
+  Lubrication, Theory of                                   202
+  Lubrication, Why Necessary                               201
+
+  M
+
+  Magnetic Circuits                                        161
+  Magnetic Influence Defined                               158
+  Magnetic Lines of Force                                  161
+  Magnetic Substances                                      158
+  Magnetism, Flow Through Armature                         166
+  Magnetism, Fundamentals of                               157
+  Magnetism, Relation to Electricity                       162
+  Magneto, Action of High Tension                          173
+  Magneto Armature Windings                                168
+  Magneto, Basic Principles of                             163
+  Magneto, Berling                                         174
+  Magneto, Defects in                                      372
+  Magneto Distributor, Cleaning                            180
+  Magneto Ignition Systems                                 169
+  Magneto Ignition Wiring                                  179
+  Magneto Interrupter, Adjustment of                       180
+  Magneto, Low Voltage                                     168
+  Magneto, Lubrication of                                  180
+  Magneto Maintenance                                      180
+  Magneto, Method of Driving                               175
+  Magneto Parts and Functions                              167
+  Magneto, The Dixie                                       184
+  Magneto Timing                                           179
+  Magneto, Timing Dixie                                    188
+  Magneto, Transformer System                              171
+  Magneto Trouble, Location of                             181
+  Magneto, True High Tension                               172
+  Magneto, Two Spark Dual                                  177
+  Magnets, Forms of                                        160
+  Magnets, How Produced                                    162
+  Magnets, Properties of                                   159
+  Main Bearings, Fitting                                   448
+  Manifold, Intake                                         143
+  Master Multiple Jet Carburetor                           133
+  Master Rod Construction                                  310
+  Maximum Theoretical Efficiency                            61
+  Meaning of Piston Speed                                  241
+  Measures of Efficiency                                    61
+  Measuring Tools                                          397
+  Mechanical Efficiency                                     62
+  Mercedes Aviation Engine                                 543
+  Metering Pin Carburetor, Stewart                         128
+  Micrometer Caliper, Beading                              405
+  Micrometer Calipers, Types and Use                       404
+  Mixture, Effect of Altitude on                           153
+  Mixture, Proportions of                                  151
+  Mixture, Starvation of                                   149
+  Monosoupape Gnome Engine                                 486
+  Mother Bod, Gnome Engine                                 305
+  Motor Misfires, Carburetor Faults Causing                374
+  Motor Misfires, Ignition Troubles Causing                370
+  Motor Races, Carburetor Faults Causing                   374
+  Motor Starts Hard, Carburetor Faults Causing             374
+  Motor Stops In Flight, Carburetor Faults                 374
+  Motor Stops Without Warning, Ignition Troubles           370
+  Multiple Cylinder Engine, Why Best                        83
+  Multiple Nozzle Vaporizers                               129
+  Multiple Valve Advantages                                286
+
+  N
+
+  Noisy Engine Operation, Causes of                        359
+  Noisy Operation, Carburetor Faults Causing               374
+  Noisy Operation, Summary of Troubles Causing             365
+
+  O
+
+  Offset Cylinders, Reason for                             243
+  Oil Bi-pass, Function of                                 213
+  Oil, Draining From Crank-case                            214
+  Oil Grooves, Cutting                                     448
+  Oil Pressure in Hall-Scott System                        214
+  Oil Pressure Relief Bi-pass                              213
+  Oiling System Defects                                    357
+  Oils for Cylinder Lubrication                            206
+  Oils for Hall-Scott Engine                               215
+  Oils for Lubrication                                     204
+  Operating Principles of Engines                           37
+  Oscillating Piston Pin                                   295
+  Otto Four-cycle Cards                                     67
+  Overhauling Aviation Engines                             412
+  Overhead Cam-shaft Location                              252
+  Overheating, Causes of                                   359
+
+  P
+
+  Panhard Concentric Valves                                255
+  Petroleum, Distillates of                                111
+  Piston, Differential                                     291
+  Piston Pin Retention                                     293
+  Piston Ring Construction                                 298
+  Piston Ring Joints                                       299
+  Piston Ring Manipulation                                 438
+  Piston Ring Troubles                                     437
+  Piston Rings, Compound                                   301
+  Piston Rings, Concentric                                 299
+  Piston Rings, Eccentric                                  299
+  Piston Rings, Fitting                                    439
+  Piston Rings, Leak Proof                                 301
+  Piston Rings, Replacing                                  441
+  Piston Speed in Airplane Engines                         241
+  Piston Speed, Meaning of                                 241
+  Piston Troubles and Remedies                             436
+  Pistons, Aluminum                                        296
+  Pistons, Details of                                      288
+  Pistons for Two-cycle Engines                            289
+  Positive Valve Systems                                   283
+  Power, Affected by High Altitude                         145
+  Power Delivery in Multiple Cylinder Engines               91
+  Power, How Obtained From Heat                             58
+  Power Needed in Airplane Engines                          21
+  Power Used in Airplanes                                   26
+  Precautions in Assembling Parts                          452
+  Pressure Relief Fitting                                  213
+  Pressures and Temperatures                                63
+  Principles of Carburetion                                112
+  Principles of Magneto Action                             163
+  Properties of Cylinder Oils                              207
+  Properties of Liquid Fuels                               110
+  Pump Circulation Systems                                 226
+  Pump Forms                                               226
+
+  R
+
+  Radial Cylinder Arrangement                              103
+  Reading Indicator Cards                                   67
+  Reamers, Types and Use                                   392
+  Reassembling Parts, Precautions in                       451
+  Removable Cylinder Head                                  239
+  Renault Air Cooled Engine                                507
+  Renault Engine Details                                   508
+  Repairing Scored Cylinders                               423
+  Requisites for Best Power Effect                          59
+  Reseating and Truing Valves                              426
+  Resistance, Influence of                                  22
+  Rotary Cylinder Engines                                  107
+  Rotary Engine, Le Rhone                                  495
+  Rotary Engines, Castor Oil for                           211
+  Rotary Engines, Installing                               342
+  Rotary Engines, Why Odd Number of Cylinders              109
+  Rotary Engines, Why Odd Number of Cylinders Is Used      482
+
+  S
+
+  S. A. E. Engine Bed Dimensions                           330
+  Salmson Nine-cylinder Engine                             470
+  Schebler Carburetor                                      125
+  Scissors Joint Rods                                      310
+  Scored Cylinders, Repairing                              422
+  Scrapers, Types of Bearing                               446
+  Scraping Bearings to Fit                                 447
+  Second Law of Gases                                       50
+  Sequence of Engine Operation                              84
+  Six-cylinder Timing Diagram                              275
+  Sixteen Valve Duesenberg Engine                          525
+  Skipping or Irregular Operation, Causes of               367
+  Sliding Sleeve Valves                                    266
+  Spark Plug Air Gaps, Setting                             197
+  Spark Plug, Design of                                    193
+  Spark Plug, Mica                                         194
+  Spark Plug, Porcelain                                    193
+  Spark Plugs, Defects in                                  371
+  Spark Plugs for Two Spark Ignition                       197
+  Spark Plug, Special for Airplane Engine                  199
+  Spark Plug, Standard S. A. E.                            195
+  Spherical Combustion Chambers                             76
+  Splash Lubrication                                       215
+  Split Pin Remover                                        384
+  Spraying Carburetors                                     120
+  Springless Valves                                        280
+  Springs, for Valves                                      263
+  Spring Winder                                            384
+  Sprung Cam-shaft, Testing                                451
+  Stand for Supporting Engine                              414
+  Starting Engine, Hints for                               361
+  Starting Hall-Scott Engine                               341
+  Starting System, Christensen                             567
+  Starting Systems, Compressed Air                         565
+  Starting Systems, Electric                               569
+  Statistics, American Engines                        546, 547
+  Statistic Sheet, Hall-Scott Engines                      544
+  Statistics of Benz Engine                                551
+  Steam Engine, Efficiency of                               59
+  Steam Engine, Why Not Used                                27
+  Steel Scale, Machinists'                                 399
+  Stewart Metering Pin Carburetor                          128
+  Storage Battery, Defects in                              372
+  Stroke and Bore Ratio                                    240
+  Sturtevant Model 5A Engine                               515
+  Summary of Engine Types                                   30
+  Sunbeam Aviation Engines                                 588
+  Sunbeam Eighteen-Cylinder Engine                         561
+
+  T
+
+  Tap and Die Sets                                         397
+  Taps for Thread Cutting                                  394
+  Tee Head Cylinders                                       247
+  Temperature Computations                                  52
+  Temperatures and Explosive Pressures                      64
+  Temperatures and Pressures                                63
+  Temperatures, Operating                                  221
+  Testing Bearing Parallelism                              453
+  Testing Connecting Rod Alignment                         454
+  Testing Fit of Bearings                                  446
+  Testing Sprung Cam-shaft                                 451
+  Theory of Gas Engine                                      47
+  Theory of Lubrication                                    203
+  Thermo-syphon Cooling System                             227
+  Thomas-Morse Aviation Engine                             521
+  Thomas-Morse Lubrication System                          210
+  Thread Pitch Gauge                                       403
+  Time of Ignition                                         273
+  Timer, Defects in                                        373
+  Times of Explosion                                        56
+  Timing Dixie Magneto                                     188
+  Timing Gears, Effects of Wear                            456
+  Timing Magneto                                           179
+  Timing Valves                                            267
+  Tool Outfits, Typical                                    408
+  Tools for Adjusting and Erecting                         378
+  Tools for Bearing Work                                   445
+  Tools for Curtiss Engines                                408
+  Tools for Grinding Valves                                430
+  Tools for Hall-Scott Engines                        410, 411
+  Tools for Measuring                                      397
+  Tools for Reseating Valves                               426
+  Trouble in Carburetion System                            355
+  Trouble, Location of Magneto                             181
+  Troubles, Engine, How to Locate                          345
+  Troubles, Ignition                                       353
+  Troubles in Oiling System                                357
+  True High Tension Magneto                                172
+  Twelve-Cylinder Engines                                   96
+  Two-and Four-Cycle Types, Comparison of                   44
+  Two-Cycle Engine Action                                   41
+  Two-Cycle Three-Port Engine                               43
+  Two-Cycle Two-Port Engine                                 42
+  Two-Spark Ignition                                       196
+  Two-Stage Carburetor                                     131
+  Types of Aircraft                                         17
+  Types of Internal Combustion Engines                      30
+
+  V
+
+  Vacuum Fuel Feed, Stewart                                119
+  Value of Compression                                      69
+  Value of Indicator Cards                                  66
+  Valve Actuation, Le Rhone                                500
+  Valve Design and Construction                            256
+  Valve-Grinding Processes                                 429
+  Valve-Lifting Cams                                       259
+  Valve-Lifting Plungers                                   260
+  Valve Location Practice                                  245
+  Valve Operating Means                                    252
+  Valve Operating System, Depreciation in                  433
+  Valve Operation                                          258
+  Valve Removal and Inspection                             424
+  Valve Seating, How to Test                               432
+  Valve Springs                                            263
+  Valve Timing, Exhaust                                    270
+  Valve Timing, Gnome Monosoupape                          278
+  Valve Timing, Intake                                     270
+  Valve Timing, Lag and Lead                               269
+  Valve Timing Procedure                                   277
+  Valve Timing Practice                                    267
+  Valves, Electric Welded                                  258
+  Valves, Flat and Bevel Seat                              257
+  Valves, Four per Cylinder                                284
+  Valves, How Placed in Cylinder                           247
+  Valves in Cages                                          249
+  Valves in Removable Heads                                249
+  Valves, Materials Used for                               258
+  Valves, Reseating                                        426
+  Vaporizer, Simple Forms of                               120
+  V Engines, Cylinder Arrangement in                       102
+  Vernier, How Used                                        401
+
+  W
+
+  Wall Cooling, Losses in                                   65
+  Water Cooling by Natural Circulation                     227
+  Water Cooling System                                     224
+  Weight of Airplane Motors                                 21
+  Wiring, Defects in                                       373
+  Wiring Magneto Ignition System                           179
+  Wisconsin Engines                                        531
+  Wrenches, Forms of                                       380
+  Wrist-pin Retention                                      293
+  Wrist-pin Retention Locks                                295
+  Wrist-pin Wear and Remedy                                442
+
+  Z
+
+  Zenith Carburetor, Action of                             137
+  Zenith Duplex Carburetor, Troubles in                    356
+  Zenith Carburetor Installation                           139
+
+
+
+
+LIST OF ILLUSTRATIONS
+
+
+Frontispiece. Part Sectional View of Hall-Scott Airplane Motor, Showing
+Principal Parts.
+
+Fig. 1. Diagrams Illustrating Computations for Horse-Power Required for
+Airplane Flight.
+
+Fig. 2. Plate Showing Heavy, Slow Speed Internal Combustion Engines Used
+Only for Stationary Power in Large Installations Giving Weight to
+Horse-Power Ratio.
+
+Fig. 3. Various Forms of Internal Combustion Engines Showing Decrease in
+Weight to Horse-Power Ratio with Augmenting Speed of Rotation.
+
+Fig. 4. Internal Combustion Engine Types of Extremely Fine Construction
+and Refined Design, Showing Great Power Outputs for Very Small Weight, a
+Feature Very Much Desired in Airplane Power Plants.
+
+Fig. 5. Outlining First Two Strokes of Piston in Four-Cycle Engine.
+
+Fig. 6. Outlining Second Two Strokes of Piston in Four-Cycle Engine.
+
+Fig. 7. Sectional View of L Head Gasoline Engine Cylinder Showing Piston
+Movements During Four-Stroke Cycle.
+
+Fig. 8. Showing Two-port, Two-cycle Engine Operation.
+
+Fig. 9. Defining Three-port, Two-cycle Engine Action.
+
+Fig. 10. Diagrams Contrasting Action of Two- and Four-Cycle Cylinders on
+Exhaust and Intake Stroke.
+
+Fig. 11. Diagram Isothermal and Adiabatic Lines.
+
+Fig. 12. Graphic Diagram Showing Approximate Utilization of Fuel Burned
+in Internal-Combustion Engine.
+
+Fig. 13. Otto Four-Cycle Card.
+
+Fig. 14. Diesel Motor Card.
+
+Fig. 15. Diagram of Heat in the Gas Engine Cylinder.
+
+Fig. 16. Chart Showing Relation Between Compression Volume and Pressure.
+
+Fig. 17. The Thompson Indicator, an Instrument for Determining
+Compressions and Explosion Pressure Values and Recording Them on Chart.
+
+Fig. 18. Spherical Combustion Chamber.
+
+Fig. 19. Enlarged Combustion Chamber.
+
+Fig. 20. Mercedes Aviation Engine Cylinder Section Showing Approximately
+Spherical Combustion Chamber and Concave Piston Top.
+
+Fig. 21. Side Sectional View of Typical Airplane Engine, Showing Parts
+and Their Relation to Each Other. This Engine is an Aeromarine Design
+and Utilizes a Distinctive Concentric Valve Construction.
+
+Fig. 22. Diagrams Illustrating Sequence of Cycles in One- and
+Two-Cylinder Engines Showing More Uniform Turning Effort on Crank-Shaft
+with Two-Cylinder Motors.
+
+Fig. 23. Diagrams Demonstrating Clearly Advantages which Obtain when
+Multiple-Cylinder Motors are Used as Power Plants.
+
+Fig. 24. Showing Three Possible Though Unconventional Arrangements of
+Four-Cylinder Engines.
+
+Fig. 25. Diagrams Outlining Advantages of Multiple Cylinder Motors, and
+Why They Deliver Power More Evenly Than Single Cylinder Types.
+
+Fig. 26. Diagrams Showing Duration of Events for a Four-Stroke Cycle,
+Six-Cylinder Engine.
+
+Fig. 27. Diagram Showing Actual Duration of Different Strokes in
+Degrees.
+
+Fig. 28. Another Diagram to Facilitate Understanding Sequence of
+Functions in Six-Cylinder Engine.
+
+Fig. 29. Types of Eight-Cylinder Engines Showing the Advantage of the V
+Method of Cylinder Placing.
+
+Fig. 30. Curves Showing Torque of Various Engine Types Demonstrate
+Graphically Marked Advantage of the Eight-Cylinder Type.
+
+Fig. 31. Diagrams Showing How Increasing Number of Cylinders Makes for
+More Uniform Power Application.
+
+Fig. 32. How the Angle Between the Cylinders of an Eight- and
+Twelve-Cylinder V Motor Varies.
+
+Fig. 33. The Hall-Scott Four-Cylinder 100 Horse-Power Aviation Motor.
+
+Fig. 34. Two Views of the Duesenberg Sixteen Valve Four-Cylinder
+Aviation Motor.
+
+Fig. 35. The Hall-Scott Six-Cylinder Aviation Engine.
+
+Fig. 36. The Curtiss Eight-Cylinder, 200 Horse-Power Aviation Engine.
+
+Fig. 37. The Sturtevant Eight-Cylinder, High Speed Aviation Motor.
+
+Fig. 38. Anzani 40-50 Horse-Power Five-Cylinder Air Cooled Engine.
+
+Fig. 39. Unconventional Six-Cylinder Aircraft Motor of Masson Design.
+
+Fig. 40. The Gnome Fourteen-Cylinder Revolving Motor.
+
+Fig. 41. How Gravity Feed Fuel Tank May Be Mounted Back of Engine and
+Secure Short Fuel Line.
+
+Fig. 42. The Stewart Vacuum Fuel Feed Tank.
+
+Fig. 43. Marine-Type Mixing Valve, by which Gasoline is Sprayed into Air
+Stream Through Small Opening in Air-Valve Seat.
+
+Fig. 44. Tracing Evolution of Modern Spray Carburetor. A--Early Form
+Evolved by Maybach. B.--Phoenix-Daimler Modification of Maybach's
+Principle. C--Modern Concentric Float Automatic Compensating Carburetor.
+
+Fig. 45. New Model of Schebler Carburetor With Metering Valve and
+Extended Venturi. Note Mechanical Connection Between Air Valve and Fuel
+Regulating Needle.
+
+Fig. 46. The Claudel Carburetor.
+
+Fig. 47. The Stewart Metering Pin Carburetor.
+
+Fig. 48. The Ball and Ball Two-Stage Carburetor.
+
+Fig. 49. The Master Carburetor.
+
+Fig. 50. Sectional View of Master Carburetor Showing Parts.
+
+Fig. 51. Sectional View of Zenith Compound Nozzle Compensating
+Carburetor.
+
+Fig. 52. Diagrams Explaining Action of Baverey Compound Nozzle Used in
+Zenith Carburetor.
+
+Fig. 53. The Zenith Duplex Carburetor for Airplane Motors of the V Type.
+
+Fig. 54. Rear View of Curtiss OX-2 90 Horse-Power Airplane Motor Showing
+Carburetor Location and Hot Air Leads.
+
+Fig. 55. Types of Strainers Interposed Between Vaporizer and Gasoline
+Tank to Prevent Water or Dirt Passing Into Carbureting Device.
+
+Fig. 56. Chart Showing Diminution of Air Pressure as Altitude Increases.
+
+Fig. 57. Some Simple Experiments to Demonstrate Various Magnetic
+Phenomena and Clearly Outline Effects of Magnetism and Various Forms of
+Magnets.
+
+Fig. 58. Elementary Form of Magneto Showing Principal Parts Simplified
+to Make Method of Current Generation Clear.
+
+Fig. 59. Showing How Strength of Magnetic Influence and of the Currents
+Induced in the Windings of Armature Vary with the Rapidity of Changes of
+Flow.
+
+Fig. 60. Diagrams Explaining Action of Low Tension Transformer Coil and
+True High Tension Magneto Ignition Systems.
+
+Fig. 60A. Side Sectional View of Bosch High-Tension Magneto Shows
+Disposition of Parts. End Elevation Depicts Arrangement of Interruptor
+and Distributor Mechanism.
+
+Fig. 61. Berling Two-Spark Dual Ignition System.
+
+Fig. 62. Berling Double-Spark Independent System.
+
+Fig. 63. Type DD Berling High Tension Magneto.
+
+Fig. 64. Wiring Diagrams of Berling Magneto Ignition Systems.
+
+Fig. 65. The Berling Magneto Breaker Box Showing Contact Points
+Separated and Interruptor Lever on Cam.
+
+Fig. 66. The Dixie Model 60 for Six-Cylinder Airplane Engine Ignition.
+
+Fig. 67. Installation Dimensions of Dixie Model 60 Magneto.
+
+Fig. 68. The Rotating Elements of the Dixie Magneto.
+
+Fig. 69. Suggestions for Adjusting and Dismantling Dixie Magneto.
+A--Screw Driver Adjusts Contact Points. B--Distributor Block Removed.
+C--Taking off Magnets. D--Showing How Easily Condenser and High Tension
+Windings are Removed.
+
+Fig. 69A. Sectional Views Outlining Construction of Dixie Magneto with
+Compound Distributor for Eight-Cylinder Engine Ignition.
+
+Fig. 70. Wiring Diagram of Dixie Magneto Installation on Hall-Scott
+Six-Cylinder 125 Horse-Power Aeronautic Motor.
+
+Fig. 71. How Magneto Ignition is Installed on Thomas-Morse 135
+Horse-Power Motor.
+
+Fig. 72. Spark-Plug Types Showing Construction and Arrangement of Parts.
+
+Fig. 73. Standard Airplane Engine Plug Suggested by S. A. E. Standards
+Committee.
+
+Fig. 74. Special Mica Plug for Aviation Engines.
+
+Fig. 75. Showing Use of Magnifying Glass to Demonstrate that Apparently
+Smooth Metal Surfaces May Have Minute Irregularities which Produce
+Friction.
+
+Fig. 76. Pressure Feed Oiling System of Thomas Aviation Engine Includes
+Oil Cooling Means.
+
+Fig. 77. Diagram of Oiling System, Hall-Scott Type A 125 Horse-Power
+Engine.
+
+Fig. 78. Sectional View of Typical Motor Showing Parts Needing
+Lubrication and Method of Applying Oil by Constant Level Splash System.
+Note also Water Jacket and Spaces for Water Circulation.
+
+Fig. 79. Pressure Feed Oil-Supply System of Airplane Power Plants has
+Many Good Features.
+
+Fig. 80. Why Pressure Feed System is Best for Eight-Cylinder Vee
+Airplane Engines.
+
+Fig. 81. Operating Temperatures of Automobile Engine Parts Useful as a
+Guide to Understand Airplane Power Plant Heat.
+
+Fig. 82. Water Cooling of Salmson Seven-Cylinder Radial Airplane Engine.
+
+Fig. 83. How Water Cooling System of Thomas Airplane Engine is Installed
+in Fuselage.
+
+Fig. 84. Finned Tube Radiators at the Side of Hall-Scott Airplane Power
+Plant Installed in Standard Fuselage.
+
+Fig. 85. Anzani Testing His Five-Cylinder Air Cooled Aviation Motor
+Installed in Bleriot Monoplane. Note Exposure of Flanged Cylinders to
+Propeller Slip Stream.
+
+Fig. 86. Views of Four-Cylinder Duesenberg Airplane Engine Cylinder
+Block.
+
+Fig. 87. Twin-Cylinder Block of Sturtevant Airplane Engine is Cast of
+Aluminum, and Has Removable Cylinder Head.
+
+Fig. 88. Aluminum Cylinder Pair Casting of Thomas 150 Horse-Power
+Airplane Engine is of the L Head Type.
+
+Fig. 90. Cross Section of Austro-Daimler Engine, Showing Offset Cylinder
+Construction. Note Applied Water Jacket and Peculiar Valve Action.
+
+Fig. 91. Diagrams Demonstrating Advantages of Offset Crank-Shaft
+Construction.
+
+Fig. 92. Diagram Showing Forms of Cylinder Demanded by Different Valve
+Placings. A--T Head Type, Valves on Opposite Sides. B--L Head Cylinder,
+Valves Side by Side. C--L Head Cylinder, One Valve in Head, Other in
+Pocket. D--Inlet Valve Over Exhaust Member, Both in Side Pocket.
+E--Valve-in-the-Head Type with Vertical Valves. F--Inclined Valves
+Placed to Open Directly into Combustion Chamber.
+
+Fig. 93. Sectional View of Engine Cylinder Showing Valve and Cage
+Installation.
+
+Fig. 94. Diagrams Showing How Gas Enters Cylinder Through Overhead
+Valves and Other Types. A--Tee Head Cylinder. B--L Head Cylinder.
+C--Overhead Valve.
+
+Fig. 95. Conventional Methods of Operating Internal Combustion Motor
+Valves.
+
+Fig. 96. Examples of Direct Valve Actuation by Overhead Cam-Shaft.
+A--Mercedes. B--Hall-Scott. C--Wisconsin.
+
+Fig. 97. CENSORED
+
+Fig. 98. CENSORED
+
+Fig. 99. Sectional Views Showing Arrangement of Novel Concentric Valve
+Arrangement Devised by Panhard for Aerial Engines.
+
+Fig. 100. Showing Clearance Allowed Between Valve Stem and Valve Stem
+Guide to Secure Free Action.
+
+Fig. 101. Forms of Valve-Lifting Cams Generally Employed. A--Cam Profile
+for Long Dwell and Quick Lift. B--Typical Inlet Cam Used with Mushroom
+Type Follower. C--Average Form of Cam. D--Designed to Give Quick Lift
+and Gradual Closing.
+
+Fig. 102. Showing Principal Types of Cam Followers which Have Received
+General Application.
+
+Fig. 103. Diagram Showing Proper Clearance to Allow Between Adjusting
+Screw and Valve Stems in Hall-Scott Aviation Engines.
+
+Fig. 104. Cam-Shaft of Thomas Airplane Motor Has Cams Forged Integral.
+Note Split Cam-Shaft Bearings and Method of Gear Retention.
+
+Fig. 105. Section Through Cylinder of Knight Motor, Showing Important
+Parts of Valve Motion.
+
+Fig. 106. Diagrams Showing Knight Sleeve Valve Action.
+
+Fig. 107. Cross Sectional View of Knight Type Eight Cylinder V Engine.
+
+Fig. 108. Diagrams Explaining Valve and Ignition Timing of Hall-Scott
+Aviation Engine.
+
+Fig. 109. Timing Diagram of Typical Six-Cylinder Engine.
+
+Fig. 110. Timing Diagram of Typical Eight-Cylinder V Engine.
+
+Fig. 111. Timing Diagram Showing Peculiar Valve Timing of Gnome
+"Monosoupape" Rotary Motor.
+
+Fig. 112. Two Methods of Operating Valves by Positive Cam Mechanism
+Which Closes as Well as Opens Them.
+
+Fig. 113. Diagram Comparing Two Large Valves and Four Small Ones of
+Practically the Same Area. Note How Easily Small Valves are Installed to
+Open Directly Into the Cylinder.
+
+Fig. 114. Sectional Views of Sixteen-Valve Four-Cylinder Automobile
+Racing Engine That May Have Possibilities for Aviation Service.
+
+Fig. 115. Front View of Curtiss OX-3 Aviation Motor, Showing
+Unconventional Valve Action by Concentric Push Rod and Pull Tube.
+
+Fig. 116. Forms of Pistons Commonly Employed in Gasoline Engines.
+A--Dome Head Piston and Three Packing Rings. B--Flat Top Form Almost
+Universally Used. C--Concave Piston Utilized in Knight Motors and Some
+Having Overhead Valves. D--Two-Cycle Engine Member with Deflector Plate
+Cast Integrally. E--Differential of Two-Diameter Piston Used in Some
+Engines Operating on Two-Cycle Principle.
+
+Fig. 117. Typical Methods of Piston Pin Retention Generally Used in
+Engines of American Design. A--Single Set Screw and Lock Nut. B--Set
+Screw and Check Nut Fitting Groove in Wrist Pin. C, D--Two Locking
+Screws Passing Into Interior of Hollow Wrist Pin. E--Split Ring Holds
+Pin in Place. F--Use of Taper Expanding Plugs Outlined. G--Spring
+Pressed Plunger Type. H--Piston Pin Pinned to Connecting Rod. I--Wrist
+Pin Clamped in Connecting Rod Small End by Bolt.
+
+Fig. 118. Typical Piston and Connecting Rod Assembly.
+
+Fig. 119. Parts of Sturtevant Aviation Engine. A--Cylinder Head Showing
+Valves. B--Connecting Rod. C--Piston and Rings.
+
+Fig. 120. Aluminum Piston and Light But Strong Steel Connecting Rod and
+Wrist Pin of Thomas Aviation Engine.
+
+Fig. 121. Cast Iron Piston of "Monosoupape" Gnome Engine Installed On
+One of the Short Connecting Rods.
+
+Fig. 122. Types of Aluminum Pistons Used In Aviation Engines.
+
+Fig. 123. Types of Piston Rings and Ring Joints. A--Concentric Ring.
+B--Eccentrically Machined Form. C--Lap Joint Ring. D--Butt Joint, Seldom
+Used. E--Diagonal Cut Member, a Popular Form.
+
+Fig. 124. Diagrams Showing Advantages of Concentric Piston Rings.
+
+Fig. 125. Leak-Proof and Other Compound Piston Rings.
+
+Fig. 126. Sectional View of Engine Showing Means of Preventing Oil
+Leakage By Piston Rings.
+
+Fig. 127. Connecting Rod and Crank-Shaft Construction of Gnome
+"Monosoupape" Engine.
+
+Fig. 128. Connecting Rod Types Summarized. A--Single Connecting Rod Made
+in One Piece, Usually Fitted in Small Single-Cylinder Engines Having
+Built-Up Crank-Shafts. B--Marine Type, a Popular Form on Heavy Engines.
+C--Conventional Automobile Type, a Modified Marine Form. D--Type Having
+Hinged Lower Cap and Split Wrist Pin Bushing. E--Connecting Rod Having
+Diagonally Divided Big End. F--Ball-Bearing Rod. G--Sections Showing
+Structural Shapes Commonly Employed in Connecting Rod Construction.
+
+Fig. 129. Double Connecting Rod Assembly For Use On Single Crank-Pin of
+Vee Engine.
+
+Fig. 130. Another Type of Double Connecting Rod for Vee Engines.
+
+Fig. 131. Part Sectional View of Wisconsin Aviation Engine, Showing
+Four-Bearing Crank-Shaft, Overhead Cam-Shaft, and Method of Combining
+Cylinders in Pairs.
+
+Fig. 132. Part Sectional View of Renault Twelve-Cylinder Water-Cooled
+Engine, Showing Connecting Rod Construction and Other Important Internal
+Parts.
+
+Fig. 133. Typical Cam-Shaft, with Valve Lifting Cams and Gears to
+Operate Auxiliary Devices Forged Integrally.
+
+Fig. 134. Important Parts of Duesenberg Aviation Engine. A--Three Main
+Bearing Crank-Shaft. B--Cam-Shaft with Integral Cams. C--Piston and
+Connecting Rod Assembly. D--Valve Rocker Group. E--Piston. F--Main
+Bearing Brasses.
+
+Fig. 135. Showing Method of Making Crank-Shaft. A--The Rough Steel
+Forging Before Machining. B--The Finished Six-Throw, Seven-Bearing
+Crank-Shaft.
+
+Fig. 136. Showing Form of Crank-Shaft for Twin-Cylinder Opposed Power
+Plant.
+
+Fig. 137. Crank-Shaft of Thomas-Morse Eight-Cylinder Vee Engine.
+
+Fig. 138. Crank-Case and Crank-Shaft Construction for Twelve-Cylinder
+Motors. A--Duesenberg. B--Curtiss.
+
+Fig. 139. Counterbalanced Crank-Shafts Reduce Engine Vibration and
+Permit of Higher Rotative Speeds.
+
+Fig. 140. View of Thomas 135 Horse-Power Aeromotor, Model 8, Showing
+Conventional Method of Crank-Case Construction.
+
+Fig. 141. Views of Upper Half of Thomas Aeromotor Crank-Case.
+
+Fig. 142. Method of Constructing Eight-Cylinder Vee Engine, Possible if
+Aluminum Cylinder and Crank-Case Castings are Used.
+
+Fig. 143. Simple and Compact Crank-Case, Possible When Radial Cylinder
+Engine Design is Followed.
+
+Fig. 144. Unconventional Mounting of German Inverted Cylinder Motor.
+
+Fig. 145. How Curtiss Model OX-2 Motor is Installed in Fuselage of
+Curtiss Tractor Biplane. Note Similarity of Mounting to Automobile Power
+Plant.
+
+Fig. 146. Latest Model of Curtiss JN-4 Training Machine, Showing
+Thorough Enclosure of Power Plant and Method of Disposing of the Exhaust
+Gases.
+
+Fig. 147. Front View of L. W. F. Tractor Biplane Fuselage, Showing
+Method of Installing Thomas Aeromotor and Method of Disposing of Exhaust
+Gases.
+
+Fig. 148. End Elevation of Hall-Scott A-7 Four-Cylinder Motor, with
+Installation Dimensions.
+
+Fig. 149. Plan and Side Elevation of Hall-Scott A-7 Four-Cylinder
+Airplane Engine, with Installation Dimensions.
+
+Fig. 150. CENSORED
+
+Fig. 151. CENSORED
+
+Fig. 152. CENSORED
+
+Fig. 153. Plan View of Hall-Scott Type A-5 125 Horse-Power Airplane
+Engine, Showing Installation Dimensions.
+
+Fig. 154. Three-Quarter View of Hall-Scott Type A-5 125 Horse-Power
+Six-Cylinder Engine, with One of the Side Radiators Removed to Show
+Installation in Standard Fuselage.
+
+Fig. 155. Diagram Showing Proper Installation of Hall-Scott Type A-5 125
+Horse-Power Engine with Pressure Feed Fuel Supply System.
+
+Fig. 156. Diagram Defining Installation of Gnome "Monosoupape" Motor in
+Tractor Biplane. Note Necessary Piping for Fuel, Oil, and Air Lines.
+
+Fig. 157. Showing Two Methods of Placing Propeller on Gnome Rotary
+Motor.
+
+Fig. 158. How Gnome Rotary Motor May Be Attached to Airplane Fuselage
+Members.
+
+Fig. 159. How Anzani Ten-Cylinder Radial Engine is Installed to Plate
+Securely Attached to Front End of Tractor Airplane Fuselage.
+
+Fig. 160. Side Elevation of Thomas 135 Horse-Power Airplane Engine,
+Giving Important Dimensions.
+
+Fig. 161. Front Elevation of Thomas-Morse 135 Horse-Power Aeromotor,
+Showing Main Dimensions.
+
+Fig. 162. Front and Side Elevations of Sturtevant Airplane Engine,
+Giving Principal Dimensions to Facilitate Installation.
+
+Fig. 163. Practical Hand Tools Useful in Dismantling and Repairing
+Airplane Engines.
+
+Fig. 164. Wrenches are Offered in Many Forms.
+
+Fig. 165. Illustrating Use and Care of Files.
+
+Fig. 166. Outlining Use of Cotter Pin Pliers, Spring Winder, and Showing
+Practical Outfit of Chisels.
+
+Fig. 167. Forms of Hand Operated Drilling Machines.
+
+Fig. 168. Forms of Drills Used in Hand and Power Drilling Machines.
+
+Fig. 169. Useful Set of Number Drills, Showing Stand for Keeping These
+in an Orderly Manner.
+
+Fig. 170. Illustrating Standard Forms of Hand and Machine Reamers.
+
+Fig. 171. Tools for Thread Cutting.
+
+Fig. 172. Showing Holder Designs for One- and Two-Piece Thread Cutting
+Dies.
+
+Fig. 173. Useful Outfit of Taps and Dies for the Engine Repair Shop.
+
+Fig. 174. Common Forms of Inside and Outside Calipers.
+
+Fig. 175. Measuring Appliances for the Machinist and Floor Man.
+
+Fig. 176. At Left, Special Form of Vernier Caliper for Measuring Gear
+Teeth; at Right, Micrometer for Accurate Internal Measurements.
+
+Fig. 177. Measuring Appliances of Value in Airplane Repair Work.
+
+Fig. 178. Standard Forms of Micrometer Caliper for External
+Measurements.
+
+Fig. 179. Special Tools for Maintaining Curtiss OX-2 Motor Used in
+Curtiss JN-4 Training Biplane.
+
+Fig. 180. Special Tools and Appliances to Facilitate Overhauling Work on
+Hall-Scott Airplane Engines.
+
+Fig. 181. Special Stand to Make Motor Overhauling Work Easier.
+
+Fig. 182. Showing Where Carbon Deposits Collect in Engine Combustion
+Chamber, and How to Burn Them Out with the Aid of Oxygen. A--Special
+Torch. B--Torch Coupled to Oxygen Tank. C--Torch in Use.
+
+Fig. 1821/2. Part Sectional View, Showing Valve Arrangement in Cylinder
+of Curtiss OX-2 Aviation Engine.
+
+Fig. 183. Tools for Restoring Valve Head and Seats.
+
+Fig. 184. Tools and Processes Utilized in Valve Grinding.
+
+Fig. 185. Outlining Points in Valve Operating Mechanism Where
+Depreciation is Apt to Exist.
+
+Fig. 186. Method of Removing Piston Rings, and Simple Clamp to
+Facilitate Insertion of Rings in Cylinder.
+
+Fig. 187. Tools and Processes Used in Refitting Engine Bearings.
+
+Fig. 188. Showing Points to Observe When Fitting Connecting Rod Brasses.
+
+Fig. 189. Methods of Testing to Insure Parallelism of Bearings After
+Fitting.
+
+Fig. 190. Views Outlining Construction of Three-Cylinder Anzani Aviation
+Motor.
+
+Fig. 190a. Illustrations Depicting Wrong and Right Methods of "Swinging
+the Stick" to Start Airplane Engine. At Top, Poor Position to Get Full
+Throw and Get Out of the Way. Below, Correct Position to Get Quick Turn
+Over of Crank-Shaft and Spring Away from Propeller.
+
+Fig. 191. The Anzani Six-Cylinder Water-Cooled Aviation Engine.
+
+Fig. 192. Sectional View of Anzani Six-Cylinder Water-Cooled Aviation
+Engine.
+
+Fig. 193. Three-Cylinder Anzani Air-Cooled Y-Form Engine.
+
+Fig. 194. Anzani Fixed Crank-Case Engine of the Six-Cylinder Form
+Utilizes Air Cooling Successfully.
+
+Fig. 195. Sectional View Showing Internal Parts of Six-Cylinder Anzani
+Engine, with Starwise Disposition of Cylinders.
+
+Fig. 196. The Anzani Ten-Cylinder Aviation Engine at the Left, and the
+Twenty-Cylinder Fixed Type at the Right.
+
+Fig. 197. Application of R. E. P. Five-Cylinder Fan-Shape Air-Cooled
+Motor to Early Monoplane.
+
+Fig. 198. The Canton and Unné Nine-Cylinder Water-Cooled Radial Engine.
+
+Fig. 199. Sectional View Showing Construction of Canton and Unné
+Water-Cooled Radial Cylinder Engine.
+
+Fig. 200. Sectional View Outlining Construction of Early Type Gnome
+Valve-in-Piston Type Motor.
+
+Fig. 201. Sectional View of Early Type Gnome Cylinder and Piston Showing
+Construction and Application of Inlet and Exhaust Valves.
+
+Fig. 202. Details of Old Style Gnome Motor Inlet and Exhaust Valve
+Construction and Operation.
+
+Fig. 203. The Gnome Fourteen-Cylinder 100 Horse-Power Aviation Engine.
+
+Fig. 204. Cam and Cam-Gear Case of the Gnome Seven-Cylinder Revolving
+Engine.
+
+Fig. 205. Diagrams Showing Why An Odd Number of Cylinders is Best for
+Rotary Cylinder Motors.
+
+Fig. 206. Simple Carburetor Used On Early Gnome Engines Attached to
+Fixed Crank-Shaft End.
+
+Fig. 207. Sectional Views of the Gnome Oil Pump.
+
+Fig. 208. Simplified Diagram Showing Gnome Motor Magneto Ignition
+System.
+
+Fig. 209. The G. V. Gnome "Monosoupape" Nine-Cylinder Rotary Engine
+Mounted on Testing Stand.
+
+Fig. 210. Sectional View Showing Construction of General Vehicle Co.
+"Monosoupape" Gnome Engine.
+
+Fig. 211. How a Gnome Cylinder is Reduced from Solid Chunk of Steel
+Weighing 97 Pounds to Finished Cylinder Weighing 51/2 Pounds.
+
+Fig. 212. The Gnome Engine Cam-Gear Case, a Fine Example of Accurate
+Machine Work.
+
+Fig. 213. G. V. Gnome "Monosoupape," with Cam-Case Cover Removed to Show
+Cams and Valve-Operating Plungers with Roller Cam Followers.
+
+Fig. 214. The 50 Horse-Power Rotary Bayerischen Motoren Gesellschaft
+Engine, a German Adaptation of the Early Gnome Design.
+
+Fig. 215. Nine-Cylinder Revolving Le Rhone Type Aviation Engine.
+
+Fig. 216. Part Sectional Views of Le Rhone Rotary Cylinder Engine,
+Showing Method of Cylinder Retention, Valve Operation and Novel Crank
+Disc Assembly.
+
+Fig. 217. Side Sectional View of Le Rhone Aviation Engine.
+
+Fig. 218. View Showing Le Rhone Valve Action and Connecting Rod Big End
+Arrangement.
+
+Fig. 219. Diagrams Showing Important Components of Le Rhone Motor.
+
+Fig. 220. How the Cams of the Le Rhone Motor Can Operate Two Valves with
+a Single Push Rod.
+
+Fig. 221. The Le Rhone Carburetor at A and Fuel Supply Regulating Device
+at B.
+
+Fig. 222. Diagrams Showing Le Rhone Motor Action and Firing Order.
+
+Fig. 223. Diagram Showing Positions of Piston in Le Rhone Rotary
+Cylinder Motor.
+
+Fig. 224. Diagrams Showing Valve Timing of Le Rhone Aviation Engine.
+
+Fig. 225. Diagrams Showing How Cylinder Cooling is Effected in Renault
+Vee Engines.
+
+Fig. 226. End Sectional View of Renault Air-Cooled Aviation Engine.
+
+Fig. 227. Side Sectional View of Renault Twelve-Cylinder Air-Cooled
+Aviation Engine Crank-Case, Showing Use of Plain and Ball Bearings for
+Crank-Shaft Support.
+
+Fig. 228. End View of Renault Twelve-Cylinder Engine Crank-Case, Showing
+Magneto Mounting.
+
+Fig. 229. Diagram Outlining Renault Twelve-Cylinder Engine Ignition
+System.
+
+Fig. 230. The Simplex Model A Hispano-Suiza Aviation Engine, a Very
+Successful Form.
+
+Fig. 231. The Curtiss OXX-5 Aviation Engine is an Eight-Cylinder Type
+Largely Used on Training Machines.
+
+Fig. 232. Top and Bottom Views of the Curtiss OXX-5 100 Horse-Power
+Aviation Engine.
+
+Fig. 233. End View of Thomas-Morse 150 Horse-Power Aluminum Cylinder
+Aviation Motor Having Detachable Cylinder Heads.
+
+Fig. 234. Side View of Thomas-Morse High Speed 150 Horse-Power Aviation
+Motor with Geared Down Propeller Drive.
+
+Fig. 235. The Reduction Gear-Case of Thomas-Morse 150 Horse-Power
+Aviation Motor, Showing Ball Bearing and Propeller Drive Shaft Gear.
+
+Fig. 236. The Six-Cylinder Aeromarine Engine.
+
+Fig. 237. The Wisconsin Aviation Engine, at Top, as Viewed from
+Carburetor Side. Below, the Exhaust Side.
+
+Fig. 238. Dimensioned End Elevation of Wisconsin Six Motor.
+
+Fig. 239. Dimensioned Side Elevation of Wisconsin Six Motor.
+
+Fig. 240. Power, Torque and Efficiency Curves of Wisconsin Aviation
+Motor.
+
+Fig. 241. Timing Diagram, Wisconsin Aviation Engine.
+
+Fig. 242. Dimensioned End View of Wisconsin Twelve-Cylinder Airplane
+Motor.
+
+Fig. 243. Dimensioned Side Elevation of Wisconsin Twelve-Cylinder
+Airplane Motor.
+
+Fig. 244. Side and End Sectional Views of Four-Cylinder Argus Engine, a
+German 100 Horse-Power Design Having Bore and Stroke of 140 mm., or 5.60
+inches, and Developing Its Power at 1,368 R.P.M. Weight, 350 Pounds.
+
+Fig. 245. Part Sectional View of 90 Horse-Power Mercedes Engine, Which
+is Typical of the Design of Larger Sizes.
+
+Fig. 246. Part Sectional Side View and Sectional End View of Benz 160
+Horse-Power Aviation Engine.
+
+Fig. 247. At Top, the Sunbeam Overhead Valve 170 Horse-Power
+Six-Cylinder Engine. Below, Side View of Sunbeam 350 Horse-Power
+Twelve-Cylinder Vee Engine.
+
+Fig. 248. Side View of Eighteen-Cylinder Sunbeam Coatalen Aircraft
+Engine Rated at 475 B.H.P.
+
+Fig. 249. Sunbeam Eighteen-Cylinder Motor, Viewed from Pump and Magneto
+End.
+
+Fig. 250. Propeller End of Sunbeam Eighteen-Cylinder 475 B.H.P. Aviation
+Engine.
+
+Fig. 251. View of Airplane Cowl Board, Showing the Various Navigating
+and Indicating Instruments to Aid the Aviator in Flight.
+
+Fig. 252. Parts of Christensen Air Starting System Shown at A, and
+Application of Piping and Check Valves to Cylinders of Thomas-Morse
+Aeromotor Outlined at B.
+
+Fig. 253. Diagrams Showing Installation of Air Starting System on
+Thomas-Morse Aviation Motor.
+
+
+
+
+  CATALOGUE
+  _Of the_ LATEST _and_ BEST
+  PRACTICAL _and_ MECHANICAL
+  BOOKS
+
+  _Including Automobile and Aviation Books_
+
+  [Illustration]
+
+
+  _Any of these books will be sent prepaid to any part of the world, on
+  receipt of price. Remit by Draft, Postal Order, Express Order or
+  Registered Letter_
+
+
+  Published and For Sale By
+  The Norman W. Henley Publishing Co.,
+  2 West 45th Street, New York, U.S.A.
+
+
+
+
+  INDEX
+
+                                             PAGES
+  Air Brakes                                21, 24
+  Arithmetic                            14, 25, 31
+  Automobile Books                      3, 4, 5, 6
+  Automobile Charts                           6, 7
+  Automobile Ignition Systems                    5
+  Automobile Lighting                            5
+  Automobile Questions and Answers               4
+  Automobile Repairing                           4
+  Automobile Starting Systems                    5
+  Automobile Trouble Charts                   5, 6
+  Automobile Welding                             5
+  Aviation                                       7
+  Aviation Chart                                 7
+  Batteries, Storage                             5
+  Bevel Gear                                    19
+  Boiler-Room Chart                              9
+  Brazing                                        7
+  Cams                                          19
+  Carburetion Trouble Chart                      6
+  Change Gear                                   19
+  Charts                                   6, 7, 8
+  Coal                                          22
+  Coke                                           9
+  Combustion                                    22
+  Compressed Air                                10
+  Concrete                              10, 11, 12
+  Concrete for Farm Use                         11
+  Concrete for Shop Use                         11
+  Cosmetics                                     27
+  Cyclecars                                      5
+  Dictionary                                    12
+  Dies                                      12, 13
+  Drawing                                   13, 14
+  Drawing for Plumbers                          28
+  Drop Forging                                  13
+  Dynamo Building                               14
+  Electric Bells                                14
+  Electric Switchboards                     14, 16
+  Electric Toy Making                           15
+  Electric Wiring                       14, 15, 16
+  Electricity                       14, 15, 16, 17
+  Encyclopedia                                  24
+  E-T Air Brake                                 24
+  Every-day Engineering                         34
+  Factory Management                            17
+  Ford Automobile                                3
+  Ford Trouble Chart                             6
+  Formulas and Recipes                          29
+  Fuel                                          17
+  Gas Construction                              18
+  Gas Engines                               18, 19
+  Gas Tractor                                   33
+  Gearing and Cams                              19
+  Glossary of Aviation Terms                 7, 12
+  Heating                                   31, 32
+  Horse-Power Chart                              9
+  Hot-Water Heating                         31, 32
+  House Wiring                              15, 17
+  How to Run an Automobile                       3
+  Hydraulics                                     5
+  Ice and Refrigeration                         20
+  Ignition Systems                               5
+  Ignition-Trouble Chart                         6
+  India Rubber                                  30
+  Interchangeable Manufacturing                 24
+  Inventions                                    20
+  Knots                                         20
+  Lathe Work                                    20
+  Link Motions                                  22
+  Liquid Air                                    21
+  Locomotive Boilers                            22
+  Locomotive Breakdowns                         22
+  Locomotive Engineering            21, 22, 23, 24
+  Machinist Book                        24, 25, 26
+  Magazine, Mechanical                          34
+  Manual Training                               26
+  Marine Engineering                            26
+  Marine Gasoline Engines                       19
+  Mechanical Drawing                        13, 14
+  Mechanical Magazine                           34
+  Mechanical Movements                          25
+  Metal Work                                12, 13
+  Motorcycles                                 5, 6
+  Patents                                       20
+  Pattern Making                                27
+  Perfumery                                     27
+  Perspective                                   13
+  Plumbing                                  28, 29
+  Producer Gas                                  19
+  Punches                                       13
+  Questions and Answers on Automobile            4
+  Questions on Heating                          32
+  Railroad Accidents                            23
+  Railroad Charts                                9
+  Recipe Book                                   29
+  Refrigeration                                 20
+  Repairing Automobiles                          4
+  Rope Work                                     20
+  Rubber                                        30
+  Rubber Stamps                                 30
+  Saw Filing                                    30
+  Saws, Management of                           30
+  Sheet-Metal Works                         12, 13
+  Shop Construction                             25
+  Shop Management                               25
+  Shop Practice                                 25
+  Shop Tools                                    25
+  Sketching Paper                               14
+  Soldering                                      7
+  Splices and Rope Work                         20
+  Steam Engineering                         30, 31
+  Steam Heating                             31, 32
+  Steel                                         32
+  Storage Batteries                              5
+  Submarine Chart                                9
+  Switchboards                              14, 16
+  Tapers                                        21
+  Telegraphy, Wireless                          17
+  Telephone                                     16
+  Thread Cutting                                26
+  Tool Making                                   24
+  Toy Making                                    15
+  Train Rules                                   23
+  Tractive Power Chart                           9
+  Tractor, Gas                                  33
+  Turbines                                      33
+  Vacuum Heating                                32
+  Valve Setting                                 22
+  Ventilation                                   31
+  Watch Making                                  33
+  Waterproofing                                 12
+  Welding with Oxy-acetylene Flame           5, 33
+  Wireless Telegraphy                           17
+  Wiring                                    14, 15
+  Wiring Diagrams                               14
+
+
+Any of these books promptly sent prepaid to any address in the world on
+receipt of price.
+
+=HOW TO REMIT=--By Postal Money Order, Express Money Order, Bank Draft
+or Registered Letter.
+
+
+~AUTOMOBILES AND MOTORCYCLES~
+
+
+=The Modern Gasoline Automobile--Its Design, Construction, and
+Operation, 1918 Edition.= By VICTOR W. PAGÉ, M.S.A.E.
+
+    This is the most complete, practical and up-to-date treatise on
+    gasoline automobiles and their component parts ever published.
+    In the new _revised_ and _enlarged_ 1918 _edition_, all phases
+    of automobile construction, operation and maintenance are fully
+    and completely described, and in language anyone can understand.
+    Every part of all types of automobiles, from light cycle-cars to
+    heavy motor trucks and tractors, are described in a thorough
+    manner, not only the automobile, but every item of it;
+    equipment, accessories, tools needed, supplies and spare parts
+    necessary for its upkeep, are fully discussed.
+
+    _It is clearly and concisely written by an expert familiar with
+    every branch of the automobile industry and the originator of
+    the practical system of self-education on technical subjects. It
+    is a liberal education in the automobile art, useful to all who
+    motor for either business or pleasure._
+
+    Anyone reading the incomparable treatise is in touch with all
+    improvements that have been made in motor-car construction. All
+    latest developments, such as high speed aluminum motors and
+    multiple valve and sleeve-valve engines, are considered in
+    detail. The latest ignition, carburetor and lubrication practice
+    is outlined. New forms of change speed gears, and final power
+    transmission systems, and all latest chassis improvements are
+    shown and described. This book is used in all leading automobile
+    schools and is conceded to be the STANDARD TREATISE. The chapter
+    on Starting and Lighting Systems has been greatly enlarged, and
+    many automobile engineering features that have long puzzled
+    laymen are explained so clearly that the underlying principles
+    can be understood by anyone. This book was first published six
+    years ago and so much new matter has been added that it is
+    nearly twice, its original size. The only treatise covering
+    various forms of war automobiles and recent developments in
+    motor-truck design as well as pleasure cars. _This book is not
+    too technical for the layman nor too elementary for the more
+    expert. It is an incomparable work of reference, for home or
+    school_. 1,000 6x9 pages, nearly 1,000 illustrations, 12 folding
+    plates. Cloth bound. Price =$3.00=
+
+    WHAT IS SAID OF THIS BOOK:
+
+    "It is the best book on the Automobile seen up to date."--J. H.
+    Pile, Associate Editor _Automobile Trade Journal_.
+
+    "Every Automobile Owner has use for a book of this
+    character."--_The Tradesman_.
+
+    "This book is superior to any treatise heretofore published on
+    the subject."--_The Inventive Age_.
+
+    "We know of no other volume that is so complete in all its
+    departments, and in which the wide field of automobile
+    construction with its mechanical intricacies is so plainly
+    handled, both in the text and in the matter of
+    illustrations."--_The Motorist_.
+
+    "The book is very thorough, a careful examination failing to
+    disclose any point in connection with the automobile, its care
+    and repair, to have been overlooked."--_Iron Age_.
+
+    "Mr. Pagé has done a great work, and benefit to the Automobile
+    Field."--W. C. Hasford, Mgr. Y. M. C. A. Automobile School,
+    Boston, Mass.
+
+    "It is just the kind of a book a motorist needs if he wants to
+    understand his car."--_American Thresherman_.
+
+
+=The Model T Ford Car, Its Construction, Operation and Repair.= By
+VICTOR W. PAGÉ, M.S.A.E.
+
+    This is a complete instruction book. All parts of the Ford Model
+    T Car are described and illustrated; the construction is fully
+    described and operating principles made clear to everyone. Every
+    Ford owner needs this practical book. You don't have to guess
+    about the construction or where the trouble is, as it shows how
+    to take all parts apart and how to locate and fix all faults.
+    The writer, Mr. Pagé, has operated a Ford car for many years and
+    writes from actual knowledge. Among the contents are: 1. The
+    Ford Car: Its Parts and Their Functions. 2. The Engine and
+    Auxiliary Groups. How the Engine Works--The Fuel Supply
+    System--The Carburetor--Making the Ignition Spark--Cooling and
+    Lubrication. 3. Details of Chassis. Change Speed Gear--Power
+    Transmission--Differential Gear Action--Steering Gear--Front
+    Axle--Frame and Springs--Brakes. 4. How to Drive and Care for
+    the Ford. The Control System Explained--Starting the
+    Motor--Driving the Car--Locating Roadside Troubles--Tire
+    Repairs--Oiling the Chassis--Winter Care of Car. 5. Systematic
+    Location of Troubles and Remedies. Faults in Engine--Faults in
+    Carburetor--Ignition Troubles--Cooling and Lubrication System
+    Defects--Adjustment of Transmission Gear--General Chassis
+    Repairs. 95 illustrations, 300 pages, 2 large folding plates.
+    Price =$1.00=
+
+
+=How to Run an Automobile.= By VICTOR W. PAGÉ, M.S.A.E.
+
+    This treatise gives concise instructions for starting and
+    running all makes of gasoline automobiles, how to care for them,
+    and gives distinctive features of control. Describes every step
+    for shifting gears, controlling engines, etc. Among the chapters
+    contained are: I.--Automobile Parts and Their Functions.
+    II.--General Starting and Driving Instructions. III.--Typical
+    1917 Control Systems. IV.--Care of Automobiles. 178 pages. 72
+    specially made illustrations. Price =$1.00=
+
+
+=Automobile Repairing Made Easy.= By VICTOR W. PAGÉ, M.S.A.E.
+
+    A comprehensive, practical exposition of every phase of modern
+    automobile repairing practice. Outlines every process incidental
+    to motor car restoration. Gives plans for workshop construction,
+    suggestions for equipment, power needed, machinery and tools
+    necessary to carry on business successfully. Tells how to
+    overhaul and repair all parts of all automobiles. Everything is
+    explained so simply that motorists and students can acquire a
+    full working knowledge of automobile repairing. This work starts
+    with the engine, then considers carburetion, ignition, cooling
+    and lubrication systems. The clutch, change speed gearing and
+    transmission system are considered in detail. Contains
+    instructions for repairing all types of axles, steering gears
+    and other chassis parts. Many tables, short cuts in figuring and
+    rules of practice are given for the mechanic. Explains fully
+    valve and magneto timing, "tuning" engines, systematic location
+    of trouble, repair of ball and roller bearings, shop kinks,
+    first aid to injured and a multitude of subjects of interest to
+    all in the garage and repair business. _This book contains
+    special instructions on electric starting_, _lighting and
+    ignition systems_, tire _repairing and rebuilding_, _autogenous
+    welding_, _brazing and soldering_, _heat treatment of steel_,
+    _latest timing practice_, _eight and twelve-cylinder motors_,
+    _etc._ 5-3/4x8. Cloth. 1,056 pages, 1,000 illustrations, 11
+    folding plates. Price =$3.00=
+
+    WHAT IS SAID OF THIS BOOK:
+
+    "'Automobile Repairing Made Easy' is the best book on the
+    subject I have ever seen and the only book I ever saw that is of
+    any value in a garage."--Fred Jeffrey, Martinsburg, Neb. "I wish
+    to thank you for sending me a copy of 'Automobile Repairing Made
+    Easy.' I do not think it could be excelled."--S. W. Gisriel,
+    Director of Instruction, Y. M. C. A., Philadelphia, Pa.
+
+
+=Questions and Answers Relating to Modern Automobile Construction,
+Driving and Repair.= By VICTOR W. PAGÉ, M.S.A.E.
+
+    A practical self-instructor for students, mechanics and
+    motorists, consisting of thirty-seven lessons in the form of
+    questions and answers, written with special reference to the
+    requirements of the non-technical reader desiring easily
+    understood, explanatory matter relating to all branches of
+    automobiling. The subject-matter is absolutely correct and
+    explained in simple language. If you can't answer all of the
+    following questions, you need this work. The answers to these
+    and over 2,000 more are to be found in its pages. Give the name
+    of all important parts of an automobile and describe their
+    functions. Describe action of latest types of kerosene
+    carburetors. What is the difference between a "double" ignition
+    system and a "dual" ignition system? Name parts of an induction
+    coil. How are valves timed? What is an electric motor starter
+    and how does it work? What are advantages of worm drive gearing?
+    Name all important types of ball and roller bearings. What is a
+    "three-quarter" floating axle? What is a two-speed axle? What is
+    the Vulcan electric gear shift? Name the causes of lost power in
+    automobiles. Describe all noises due to deranged mechanism and
+    give causes? How can you adjust a carburetor by the color of the
+    exhaust gases? What causes "popping" in the carburetor? What
+    tools and supplies are needed to equip a car? How do you drive
+    various makes of cars? What is a differential lock and where is
+    it used? Name different systems of wire wheel construction,
+    etc., etc. A popular work at a popular price. 5-1/4x7-1/2.
+    Cloth. 650 pages, 350 illustrations, 3 folding plates. Price
+    =$1.50=
+
+    WHAT IS SAID OF THIS BOOK:
+
+    "If you own a car--get this book."--_The Glassworker_.
+
+    "Mr. Page has the faculty of making difficult subjects plain and
+    understandable."--_Bristol Press_.
+
+    "We can name no writer better qualified to prepare a book of
+    instruction on automobiles than Mr. Victor W.
+    Pagé."--_Scientific American_.
+
+    "The best automobile catechism that has appeared."--_Automobile
+    Topics_.
+
+    "There are few men, even with long experience, who will not find
+    this book useful. Great pains have been taken to make it
+    accurate. Special recommendation must be given to the
+    illustrations, which have been made specially for the work. Such
+    excellent books as this greatly assist in fully understanding
+    your automobile."--_Engineering News_.
+
+
+=The Automobilist's Pocket Companion and Expense Record.= Arranged by
+VICTOR W. PAGÉ, M.S.A.E.
+
+    This book is not only valuable as a convenient cost record but
+    contains much information of value to motorists. Includes a
+    condensed digest of auto laws of all States, a lubrication
+    schedule, hints for care of storage battery and care of tires,
+    location of road troubles, anti-freezing solutions, horse-power
+    table, driving hints and many useful tables and recipes of
+    interest to all motorists. Not a technical book in any sense of
+    the word, just a collection of practical facts in simple
+    language for the everyday motorist. Price =$1.00=
+
+
+=Modern Starting, Lighting and Ignition Systems.= By VICTOR W. PAGÉ,
+M.E.
+
+    This practical volume has been written with special reference to
+    the requirements of the non-technical reader desiring easily
+    understood, explanatory matter, relating to all types of
+    automobile ignition, starting and lighting systems. It can be
+    understood by anyone, even without electrical knowledge, because
+    elementary electrical principles are considered before any
+    attempt is made to discuss features of the various systems.
+    These basic principles are clearly stated and illustrated with
+    simple diagrams. _All the leading systems of starting, lighting
+    and ignition have been described and illustrated with the
+    co-operation of the experts employed by the manufacturers._
+    Wiring diagrams are shown in both technical and non-technical
+    forms. All symbols are fully explained. It is a comprehensive
+    review of modern starting and ignition system practice, and
+    includes a complete exposition of storage battery construction,
+    care and repair. All types of starting motors, generators,
+    magnetos, and all ignition or lighting system-units are fully
+    explained. _Every person in the automobile business needs this
+    volume._ Among some of the subjects treated are: I.--Elementary
+    Electricity; Current Production; Flow; Circuits; Measurements;
+    Definitions; Magnetism; Battery Action; Generator Action.
+    II.--Battery Ignition Systems. III.--Magneto Ignition Systems.
+    IV.--Elementary Exposition of Starting System Principles.
+    V.--Typical Starting and Lighting Systems; Practical
+    Application; Wiring Diagrams; Auto-lite, Bijur, Delco,
+    Dyneto-Entz, Gray and Davis, Remy, U. S. L., Westinghouse,
+    Bosch-Rushmore, Genemotor, North-East, etc. VI.--Locating and
+    Repairing Troubles in Starting and Lighting Systems.
+    VII.--Auxiliary. Electric Systems; Gear-shifting by Electricity;
+    Warning Signals; Electric Brake; Entz-Transmission, Wagner-Saxon
+    Circuits, Wagner-Studebaker Circuits. 5-1/4x7-1/2. Cloth. 530
+    pages, 297 illustrations, 3 folding plates. Price =$1.50=
+
+
+=Automobile Welding With the Oxy-Acetylene Flame.= By M. KEITH DUNHAM.
+
+    This is the only complete book on the "why" and "how" of Welding
+    with the Oxy-Acetylene Flame, and from its pages one can gain
+    information so that he can weld anything that comes along.
+
+    No one can afford to be without this concise book, as it first
+    explains the apparatus to be used, and then covers in detail the
+    actual welding of all automobile parts. The welding of aluminum,
+    cast iron, steel, copper, brass and malleable iron is clearly
+    explained, as well as the proper way to burn the carbon out of
+    the combustion head of the motor. Among the contents are:
+    Chapter I.--Apparatus Knowledge. Chapter II.--Shop Equipment and
+    Initial Procedure. Chapter III.--Cast Iron. Chapter
+    IV.--Aluminum. Chapter V.--Steel. Chapter VI.--Malleable Iron,
+    Copper, Brass, Bronze. Chapter VII.--Carbon Burning and other
+    Uses of Oxygen and Acetylene. Chapter VIII.--How to Figure Cost
+    of Welding. 167 pages, fully illustrated. Price =$1.00=
+
+
+=Storage Batteries Simplified.= By VICTOR W. PAGÉ, M.S.A.E.
+
+    A comprehensive treatise devoted entirely to secondary batteries
+    and their maintenance, repair and use.
+
+    This is the most up-to-date book on this subject. Describes
+    fully the Exide, Edison, Gould, Willard, U. S. L. and other
+    storage battery forms in the types best suited for automobile,
+    stationary and marine work. Nothing of importance has been
+    omitted that the reader should know about the practical
+    operation and care of storage batteries. No details have been
+    slighted. The instructions for charging and care have been made
+    as simple as possible. Brief Synopsis of Chapters: Chapter
+    I.--Storage Battery Development; Types of Storage Batteries;
+    Lead Plate Types; The Edison Cell. Chapter II.--Storage Battery
+    Construction; Plates and Girds; Planté Plates; Fauré Plates;
+    Non-Lead Plates; Commercial Battery Designs. Chapter
+    III.--Charging Methods; Rectifiers; Converters; Rheostats; Rules
+    for Charging. Chapter IV.--Battery Repairs and Maintenance.
+    Chapter V.--Industrial Application of Storage Batteries;
+    Glossary of Storage Battery Terms. 208 Pages. Very Fully
+    Illustrated. Price =$1.50 net=.
+
+
+=Motorcycles, Side Cars and Cyclecars; their Construction, Management
+and Repair.= By VICTOR W. PAGÉ, M.S.A.E.
+
+    The only complete work published for the motorcyclist and
+    cyclecarist. Describes fully all leading types of machines,
+    their design, construction, maintenance, operation and repair.
+    This treatise outlines fully the operation of two- and
+    four-cycle power plants and all ignition, carburetion and
+    lubrication systems in detail. Describes all representative
+    types of free engine clutches, variable speed gears and power
+    transmission systems. Gives complete instructions for operating
+    and repairing all types. Considers fully electric self-starting
+    and lighting systems, all types of spring frames and spring
+    forks and shows leading control methods. For those desiring
+    technical information a complete series of tables and many
+    formulæ to assist in designing are included. The work tells how
+    to figure power needed to climb grades, overcome air resistance
+    and attain high speeds. It shows how to select gear ratios for
+    various weights and powers, how to figure braking efficiency
+    required, gives sizes of belts and chains to transmit power
+    safely, and shows how to design sprockets, belt pulleys, etc.
+    This work also includes complete formulæ for figuring
+    horse-power, shows how dynamometer tests are made, defines
+    relative efficiency of air and water-cooled engines, plain and
+    anti-friction bearings and many other data of a practical,
+    helpful, engineering nature. Remember that you get this
+    information in addition to the practical description and
+    instructions which alone are worth several times the price of
+    the book. 550 pages. 350 specially made illustrations, 5 folding
+    plates. Cloth. Price =$1.50=
+
+    WHAT IS SAID OF THIS BOOK:
+
+    "Here is a book that should be in the cycle repairer's
+    kit."--_American Blacksmith._
+
+    "The best way for any rider to thoroughly understand his
+    machine, is to get a copy of this book; it is worth many times
+    its price."--_Pacific Motorcyclist._
+
+
+~AUTOMOBILE AND MOTORCYCLE CHARTS~
+
+
+=Chart. Location of Gasoline Engine Troubles Made Easy--A Chart Showing
+Sectional View of Gasoline Engine.= Compiled by VICTOR W. PAGÉ, M.S.A.E.
+
+    It shows clearly all parts of a typical four-cylinder gasoline
+    engine of the four-cycle type.
+
+    It outlines distinctly all parts liable to give trouble and also
+    details the derangements apt to interfere with smooth engine
+    operation.
+
+    Valuable to students, motorists, mechanics, repairmen,
+    garagemen, automobile salesmen, chauffeurs, motorboat owners,
+    motor-truck and tractor drivers, aviators, motor-cyclists, and
+    all others who have to do with gasoline power plants.
+
+    It simplifies location of all engine troubles, and while it will
+    prove invaluable to the novice, it can be used to advantage by
+    the more expert. It should be on the walls of every public and
+    private garage, automobile repair shop, club house or school. It
+    can be carried in the automobile or pocket with ease, and will
+    insure against loss of time when engine trouble manifests
+    itself.
+
+    This sectional view of engine is a complete review of all motor
+    troubles. It is prepared by a practical motorist for all who
+    motor. More information for the money than ever before offered.
+    No details omitted. Size 25x38 inches. Securely mailed on
+    receipt of =25 Cents=
+
+
+=Chart. Location of Ford Engine Troubles Made Easy.= Compiled by VICTOR
+W. PAGÉ, M.S.A.E.
+
+    This shows clear sectional views depicting all portions of the
+    Ford power plant and auxiliary groups. It outlines clearly all
+    parts of the engine, fuel supply system, ignition group and
+    cooling system, that are apt to give trouble, detailing all
+    derangements that are liable to make an engine lose power, start
+    hard or work irregularly. This chart is valuable to students,
+    owners, and drivers, as it simplifies location of all engine
+    faults. Of great advantage as an instructor for the novice, it
+    can be used equally well by the more expert as a work of
+    reference and review. It can be carried in the tool-box or
+    pocket with ease and will save its cost in labor eliminated the
+    first time engine trouble manifests itself. Prepared with
+    special reference to the average man's needs and is a practical
+    review of all motor troubles because it is based on the actual
+    experience of an automobile engineer-mechanic with the mechanism
+    the chart describes. It enables the non-technical owner or
+    operator of a Ford car to locate engine derangements by
+    systematic search, guided by easily recognized symptoms instead
+    of by guesswork. It makes the average owner independent of the
+    roadside repair shop when touring. Must be seen to be
+    appreciated. Size 25x38 inches. Printed on heavy bond paper.
+    Price =25 cents=
+
+
+=Chart. Lubrication of the Motor Car Chassis.= Compiled by VICTOR W.
+PAGÉ, M.S.A.E.
+
+    This chart presents the plan view of a typical six-cylinder
+    chassis of standard design and all parts are clearly indicated
+    that demand oil, also the frequency with which they must be
+    lubricated and the kind of oil to use. A practical chart for all
+    interested in motor-car maintenance. Size 24x38 inches. Price
+    =25 cents=
+
+
+=Chart. Location of Carburetion Troubles Made Easy.= Compiled by VICTOR
+W. PAGÉ, M.S.A.E.
+
+    This chart shows all parts of a typical pressure feed fuel
+    supply system and gives causes of trouble, how to locate defects
+    and means of remedying them. Size 24x38 inches. Price =25 cents=
+
+
+=Chart. Location of Ignition System Troubles Made Easy.= Compiled by
+VICTOR W. PAGÉ, M.S.A.E.
+
+    In this diagram all parts of a typical double ignition system
+    using battery and magneto current are shown, and suggestions are
+    given for readily finding ignition troubles and eliminating them
+    when found. Size 24x38 inches. Price =25 cents=
+
+
+=Chart. Location of Cooling and Lubrication System Faults.= Compiled by
+VICTOR W. PAGÉ, M.S.A.E.
+
+    This composite diagram shows a typical automobile power plant
+    using pump circulated water-cooling system and the most popular
+    lubrication method. Gives suggestions for curing all overheating
+    and loss of power faults due to faulty action of the oiling or
+    cooling group. Size 24x38 inches. Price =25 cents=
+
+
+=Chart. Motorcycle Troubles Made Easy.= Compiled by VICTOR W PAGÉ,
+M.S.A.E.
+
+    A chart showing sectional view of a single-cylinder gasoline
+    engine. This chart simplifies location of all power-plant
+    troubles. A single-cylinder motor is shown for simplicity. It
+    outlines distinctly all parts liable to give trouble and also
+    details the derangements apt to interfere with smooth engine
+    operation. This chart will prove of value to all who have to do
+    with the operation, repair or sale of motorcycles. No details
+    omitted. Size 30x20 inches Price =25 cents=
+
+
+~AVIATION~
+
+
+=Aviation Engines, their Design, Construction, Operation and Repair.= By
+Lieut. VICTOR W. PAGÉ, Aviation Section, S.C.U.S.R.
+
+    A practical work containing valuable instructions for aviation
+    students, mechanicians, squadron engineering officers and all
+    interested in the construction and upkeep of airplane power
+    plants.
+
+    The rapidly increasing interest in the study of aviation, and
+    especially of the highly developed internal combustion engines
+    that make mechanical flight possible, has created a demand for a
+    text-book suitable for schools and home study that will clearly
+    and concisely explain the workings of the various aircraft
+    engines of foreign and domestic manufacture.
+
+    This treatise, written by a recognized authority on all of the
+    practical aspects of internal combustion engine construction,
+    maintenance and repair fills the need as no other book does.
+
+    The matter is logically arranged; all descriptive matter is
+    simply expressed and copiously illustrated so that anyone can
+    understand airplane engine operation and repair even if without
+    previous mechanical training. This work is invaluable for anyone
+    desiring to become an aviator or aviation mechanician.
+
+    The latest rotary types, such as the Gnome, Monosoupape, and Le
+    Rhone, are fully explained, as well as the recently developed
+    Vee and radial types. The subjects of carburetion, ignition,
+    cooling and lubrication also are covered in a thorough manner.
+    The chapters on repair and maintenance are distinctive and found
+    in no other book on this subject.
+
+    Invaluable to the student, mechanic and soldier wishing to enter
+    the aviation service.
+
+    Not a technical book, but a practical, easily understood work of
+    reference for all interested in aeronautical science. 576 octavo
+    pages. 253 specially made engravings. Price =$3.00 net=
+
+
+~GLOSSARY OF AVIATION TERMS~
+
+
+=Termes D'Aviation, English-French, French-English.= Compiled by Lieuts.
+VICTOR W. PAGÉ, A.S., S.C.U.S.R., and PAUL MONTARIOL of the French
+Flying Corps, on duty on Signal Corps Aviation School, Mineola, L. I.
+
+    A complete, well illustrated volume intended to facilitate
+    conversation between English-speaking and French aviators. A
+    very valuable book for all who are about to leave for duty
+    overseas.
+
+    Approved for publication by Major W. G. Kilner, S.C., U.S.C.O.
+    Signal Corps Aviation School. Hazelhurst Field, Mineola, L. I.
+
+    This book should be in every Aviator's and Mechanic's Kit for
+    ready reference. 128 pages. Fully illustrated with detailed
+    engravings. Price =$1.00=
+
+
+=Aviation Chart. Location of Airplane Power Plant Troubles Made Easy.=
+By Lieut. VICTOR W. PAGÉ, A.S., S.C.U.S.R.
+
+    A large chart outlining all parts of a typical airplane power
+    plant, showing the points where trouble is apt to occur and
+    suggesting remedies for the common defects. Intended especially
+    for Aviators and Aviation Mechanics on School and Field Duty.
+    Price =50 cents=
+
+
+~BRAZING AND SOLDERING~
+
+
+=Brazing and Soldering.= By JAMES F. HOBART.
+
+    The only book that shows you just how to handle any job of
+    brazing or soldering that comes along; it tells you what mixture
+    to use, how to make a furnace if you need one. Full of valuable
+    kinks. The fifth edition of this book has just been published,
+    and to it much new matter and a large number of tested formulæ
+    for all kinds of solders and fluxes have been added.
+    Illustrated. Price =25 cents=
+
+
+~CHARTS~
+
+
+=Aviation Chart. Location of Airplane Power Plant Troubles Made Easy.=
+By Lieut. VICTOR W. PAGÉ, A.S., S.C.U.S.R.
+
+    A large chart outlining all parts of a typical airplane power
+    plant, showing the points where trouble is apt to occur and
+    suggesting remedies for the common defects. Intended especially
+    for Aviators and Aviation Mechanics on School and Field Duty.
+    Price =50 cents=
+
+
+=Gasoline Engine Troubles Made Easy--A Chart Showing Sectional View of
+Gasoline Engine.= Compiled by Lieut. VICTOR W. PAGÉ, A.S., S.C.U.S.R.
+
+    It shows clearly all parts of a typical four-cylinder gasoline
+    engine of the four-cycle type. It outlines distinctly all parts
+    liable to give trouble and also details the derangements apt to
+    interfere with smooth engine operation.
+
+    Valuable to students, motorists, mechanics, repairmen,
+    garagemen, automobile salesmen, chauffeurs, motor-boat owners,
+    motor-truck and tractor drivers, aviators, motor-cyclists, and
+    all others who have to do with gasoline power plants.
+
+    It simplifies location of all engine troubles, and while it will
+    prove invaluable to the novice, it can be used to advantage by
+    the more expert. It should be on the walls of every public and
+    private garage, automobile repair shop, club house or school. It
+    can be carried in the automobile or pocket with ease and will
+    insure against loss of time when engine trouble manifests
+    itself.
+
+    This sectional view of engine is a complete review of all motor
+    troubles. It is prepared by a practical motorist for all who
+    motor. No details omitted. Size 25x38 inches. Price =25 cents=
+
+
+=Lubrication of the Motor Car Chassis.=
+
+    This chart presents the plan view of a typical six-cylinder
+    chassis of standard design and all parts are clearly indicated
+    that demand oil, also the frequency with which they must be
+    lubricated and the kind of oil to use. A practical chart for all
+    interested in motor-car maintenance. Size 24x38 inches. Price
+    =25 cents=
+
+
+=Location of Carburetion Troubles Made Easy.=
+
+    This chart shows all parts of a typical pressure feed fuel
+    supply system and gives causes of trouble, how to locate defects
+    and means of remedying them. Size 24x38 inches. Price =25 cents=
+
+
+=Location of Ignition System Troubles Made Easy.=
+
+    In this chart all parts of a typical double ignition system
+    using battery and magneto current are shown and suggestions are
+    given for readily finding ignition troubles and eliminating them
+    when found. Size 24x38 inches. Price =25 cents=
+
+
+=Location of Cooling and Lubrication System Faults.=
+
+    This composite chart shows a typical automobile power plant
+    using pump circulated water-cooling system and the most popular
+    lubrication method. Gives suggestions for curing all overheating
+    and loss of power faults due to faulty action of the oiling or
+    cooling group. Size 24x38 inches. Price =25 Cents=
+
+
+=Motorcycle Troubles Made Easy--A Chart Showing Sectional View of
+Single-Cylinder Gasoline Engine.= Compiled by VICTOR W. PAGÉ, M.S.A.E.
+
+    This chart simplifies location of all power-plant troubles, and
+    will prove invaluable to all who have to do with the operation,
+    repair or sale of motorcycles. No details omitted. Size 25x38
+    inches. Price =25 cents=
+
+
+=Location of Ford Engine Troubles Made Easy.= Compiled by VICTOR W.
+PAGÉ, M.S.A.E.
+
+    This shows clear sectional views depicting all portions of the
+    Ford power plant and auxiliary groups. It outlines clearly all
+    parts of the engine, fuel supply system, ignition group and
+    cooling system, that are apt to give trouble, detailing all
+    derangements that are liable to make an engine lose power, start
+    hard or work irregularly. This chart is valuable to students,
+    owners, and drivers, as it simplifies location of all engine
+    faults. Of great advantage as an instructor for the novice, it
+    can be used equally well by the more expert as a work of
+    reference and review. It can be carried in the toolbox or pocket
+    with ease and will save its cost in labor eliminated the first
+    time engine trouble manifests itself. Prepared with special
+    reference to the average man's needs and is a practical review
+    of all motor troubles because it is based on the actual
+    experience of an automobile engineer-mechanic with the mechanism
+    the chart describes. It enables the non-technical owner or
+    operator of a Ford car to locate engine derangements by
+    systematic search, guided by easily recognized symptoms instead
+    of by guesswork. It makes the average owner independent of the
+    roadside repair shop when touring. Must be seen to be
+    appreciated. Size 25x38 inches. Printed on heavy bond paper.
+    Price =25 cents=
+
+=Modern Submarine Chart--with Two Hundred Parts Numbered and Named.=
+
+    A cross-section view, showing clearly and distinctly all the
+    interior of a Submarine of the latest type. You get more
+    information from this chart, about the construction and
+    operation of a Submarine, than in any other way. No details
+    omitted--everything is accurate and to scale. It is absolutely
+    correct in every detail, having been approved by Naval
+    Engineers. All the machinery and devices fitted in a modern
+    Submarine Boat are shown, and to make the engraving more readily
+    understood all the features are shown in operative form, with
+    Officers and Men in the act of performing the duties assigned to
+    them in service conditions. This CHART IS REALLY AN ENCYCLOPEDIA
+    OF A SUBMARINE. It is educational and worth many times its cost.
+    Mailed in a Tube for =25 Cents=
+
+
+=Box Car Chart.=
+
+    A chart showing the anatomy of a box car, having every part of
+    the car numbered and its proper name given in a reference list.
+    Price =25 Cents=
+
+
+=Gondola Car Chart.=
+
+    A chart showing the anatomy of a gondola car, having every part
+    of the car numbered and its proper reference name given in a
+    reference list. Price =25 Cents=
+
+
+=Passenger-Car Chart.=
+
+    A chart showing the anatomy of a passenger-car, having every
+    part of the car numbered and its proper name given in a
+    reference list =25 Cents=
+
+
+=Steel Hopper Bottom Coal Car.=
+
+    A chart showing the anatomy of a steel Hopper Bottom Coal Car,
+    having every part of the car numbered and its proper name given
+    in a reference list. Price =25 Cents=
+
+
+=Tractive Power Chart.=
+
+    A chart whereby you can find the tractive power or drawbar pull
+    of any locomotive without making a figure. Shows what cylinders
+    are equal, how driving wheels and steam pressure affect the
+    power. What sized engine you need to exert a given drawbar pull
+    or anything you desire in this line. Price =50 Cents=
+
+
+=Horse-Power Chart.=
+
+    Shows the horse-power of any stationary engine without
+    calculation. No matter what the cylinder diameter of stroke, the
+    steam pressure of cut-off, the revolutions, or whether
+    condensing or non-condensing, it's all there. Easy to use,
+    accurate, and saves time and calculations. Especially useful to
+    engineers and designers. Price =50 Cents=
+
+
+=Boiler Room Chart.= By GEO. L. FOWLER.
+
+    A chart--size 14x28 inches--showing in isometric perspective the
+    mechanisms belonging in a modern boiler room. The various parts
+    are shown broken or removed, so that the internal construction
+    is fully illustrated. Each part is given a reference number, and
+    these, with the corresponding name, are given in a glossary
+    printed at the sides. This chart is really a dictionary of the
+    boiler room--the names of more than 200 parts being given. Price
+    =25 Cents=
+
+
+~COKE~
+
+
+=Modern Coking Practice, Including Analysis of Materials and Products.=
+
+By J. E. CHRISTOPHER and T. H. BYROM.
+
+    This, the standard work on the subject, has just been revised.
+    It is a practical work for those engaged in Coke manufacture and
+    the recovery of By-products. Fully illustrated with folding
+    plates. It has been the aim of the authors, in preparing this
+    book, to produce one which shall be of use and benefit to those
+    who are associated with, or interested in, the modern
+    developments of the industry. Among the Chapters contained in
+    Volume I are: Introduction; Classification of Fuels; Impurities
+    of Coals; Coal Washing; Sampling and Valuation of Coals, etc.;
+    Power of Fuels; History of Coke Manufacture; Developments in the
+    Coke Oven Design; Recent Types of Coke Ovens; Mechanical
+    Appliances at Coke Ovens; Chemical and Physical Examination of
+    Coke. Volume II covers fully the subject of By-Products. Price,
+    per volume =$3.00 net=
+
+
+~COMPRESSED AIR~
+
+
+=Compressed Air in All Its Applications.= By GARDNER D. HISCOX.
+
+    This is the most complete book on the subject of Air that has
+    ever been issued, and its thirty-five chapters include about
+    every phase of the subject one can think of. It may be called an
+    encyclopedia of compressed air. It is written by an expert, who,
+    in its 665 pages, has dealt with the subject in a comprehensive
+    manner, no phase of it being omitted. Includes the physical
+    properties of air from a vacuum to its highest pressure, its
+    thermodynamics, compression, transmission and uses as a motive
+    power, in the Operation of Stationary and Portable Machinery, in
+    Mining, Air Tools, Air Lifts, Pumping of Water, Acids, and Oils;
+    the Air Blast for Cleaning and Painting the Sand Blast and its
+    Work, and the Numerous Appliances in which Compressed Air is a
+    Most Convenient and Economical Transmitter of Power for
+    Mechanical Work, Railway Propulsion, Refrigeration, and the
+    Various Uses to which Compressed Air has been applied. Includes
+    forty-four tables of the physical properties of air, its
+    compression, expansion, and volumes required for various kinds
+    of work, and a list of patents on compressed air from 1875 to
+    date. Over 500 illustrations, 5th Edition, revised and enlarged.
+
+    Cloth bound. Price =$5.00=
+
+    Half Morocco. Price =$6.50=
+
+
+~CONCRETE~
+
+
+=Concrete Workers' Reference Books. A Series of Popular Handbooks for
+Concrete Users.= Prepared by A. A. HOUGHTON =50 cents=
+
+    _The author, in preparing this Series, has not only treated on
+    the usual types of construction, but explains and illustrates
+    molds and systems that are not patented, but which are equal in
+    value and often superior to those restricted by patents. These
+    molds are very easily and cheaply constructed and embody
+    simplicity, rapidity of operation, and the most successful
+    results in the molded concrete. Each of these books is fully
+    illustrated, and the subjects are exhaustively treated in plain
+    English._
+
+
+=Concrete Wall Forms.= By A. A. HOUGHTON.
+
+    A new automatic wall clamp is illustrated with working drawings.
+    Other types of wall forms, clamps, separators, etc., are also
+    illustrated and explained. (No. 1 of Series) Price =50 cents=
+
+
+=Concrete Floors and Sidewalks.= By A. A. HOUGHTON.
+
+    The molds for molding squares, hexagonal and many other styles
+    of mosaic floor and sidewalk blocks are fully illustrated and
+    explained. (No. 2 of Series) Price =50 cents=
+
+
+=Practical Concrete Silo Construction.= By A. A. HOUGHTON.
+
+    Complete working drawings and specifications are given for
+    several styles of concrete silos, with illustrations of molds
+    for monolithic and block silos. The tables, data, and
+    information presented in this book are of the utmost value in
+    planning and constructing all forms of concrete silos. (No. 3 of
+    Series) Price =50 cents=
+
+
+=Molding Concrete Chimneys, Slate and Hoof Tiles.= By A. A. HOUGHTON.
+
+    The manufacture of all types of concrete slate and roof tile is
+    fully treated. Valuable data on all forms of reinforced concrete
+    roofs are contained within its pages. The construction of
+    concrete chimneys by block and monolithic systems is fully
+    illustrated and described. A number of ornamental designs of
+    chimney construction with molds are shown in this valuable
+    treatise. (No. 4 of Series.) Price =50 cents=
+
+
+=Molding and Curing Ornamental Concrete.= By A. A. HOUGHTON.
+
+    The proper proportions of cement and aggregates for various
+    finishes, also the method of thoroughly mixing and placing in
+    the molds, are fully treated. An exhaustive treatise on this
+    subject that every concrete worker will find of daily use and
+    value. (No. 5 of Series.) Price =50 cents=
+
+
+=Concrete Monuments, Mausoleums and Burial Vaults.= By A. A. HOUGHTON.
+
+    The molding of concrete monuments to imitate the most expensive
+    cut stone is explained in this treatise with working drawings of
+    easily built molds. Cutting inscriptions and designs are also
+    fully treated. (No. 6 of Series.) Price =50 cents=
+
+
+=Molding Concrete Bathtubs, Aquariums and Natatoriums.= By A. A.
+HOUGHTON.
+
+    Simple molds and instruction are given for molding many styles
+    of concrete bathtubs, swimming-pools, etc. These molds are
+    easily built and permit rapid and successful work. (No. 7 of
+    Series.) Price =50 cents=
+
+
+=Concrete Bridges, Culverts and Sewers.= By A. A. HOUGHTON.
+
+    A number of ornamental concrete bridges with illustrations of
+    molds are given. A collapsible center or core for bridges,
+    culverts and sewers is fully illustrated with detailed
+    instructions for building. (No. 8 of Series.) Price =50 cents=
+
+
+=Constructing Concrete Porches.= By A. A. HOUGHTON.
+
+    A number of designs with working drawings of molds are fully
+    explained so any one can easily construct different styles of
+    ornamental concrete porches without the purchase of expensive
+    molds. (No. 9 of Series.) Price =50 cents=
+
+
+=Molding Concrete Flower-Pots, Boxes, Jardinieres, Etc.= By A. A.
+HOUGHTON.
+
+    The molds for producing many original designs of flower-pots,
+    urns, flower-boxes, jardinieres, etc., are fully illustrated and
+    explained, so the worker can easily construct and operate same.
+    (No. 10 of Series.) Price =50 cents=
+
+
+=Molding Concrete Fountains and Lawn Ornaments.= By A. A. HOUGHTON.
+
+    The molding of a number of designs of lawn seats, curbing,
+    hitching posts, pergolas, sun dials and other forms of
+    ornamental concrete for the ornamentation of lawns and gardens,
+    is fully illustrated and described. (No. 11 of Series.) Price
+    =50 cents=
+
+
+=Concrete from Sand Molds.= By A. A. HOUGHTON.
+
+    A Practical Work treating on a process which has heretofore been
+    held as a trade secret by the few who possessed it, and which
+    will successfully mold every and any class of ornamental
+    concrete work. The process of molding concrete with sand molds
+    is of the utmost practical value, possessing the manifold
+    advantages of a low cost of molds, the ease and rapidity of
+    operation, perfect details to all ornamental designs, density
+    and increased strength of the concrete, perfect curing of the
+    work without attention and the easy removal of the molds
+    regardless of any undercutting the design may have. 192 pages.
+    Fully illustrated Price =$2.00=
+
+
+=Ornamental Concrete without Molds.= By A. A. HOUGHTON.
+
+    The process for making ornamental concrete without molds has
+    long been held as a secret, and now, for the first time, this
+    process is given to the public. The book reveals the secret and
+    is the only book published which explains a simple, practical
+    method whereby the concrete worker is enabled, by employing wood
+    and metal templates of different designs, to mold or model in
+    concrete any Cornice, Archivolt, Column, Pedestal, Base Cap, Urn
+    or Pier in a monolithic form--right upon the job. These may be
+    molded in units or blocks and then built up to suit the
+    specifications demanded. This work is fully illustrated, with
+    detailed engravings. Price =$2.00=
+
+
+=Concrete for the Farm and in the Shop.= By H. COLIN CAMPBELL, C.E.,
+E.M.
+
+    "Concrete for the Farm and in the Shop" is a new book from cover
+    to cover, illustrating and describing in plain, simple language
+    many of the numerous applications of concrete within the range
+    of the home worker. Among the subjects treated are: Principles
+    of Reinforcing; Methods of Protecting Concrete so as to Insure
+    Proper Hardening; Home-made Mixers; Mixing by Hand and Machine;
+    Form Construction, Described and Illustrated by Drawings and
+    Photographs; Construction of Concrete Walls and Fences; Concrete
+    Fence Posts; Concrete Gate Posts; Corner Posts; Clothes Line
+    Posts; Grape Arbor Posts; Tanks; Troughs; Cisterns; Hog Wallows;
+    Feeding Floors and Barnyard Pavements; Foundations; Well Curbs
+    and Platforms; Indoor Floors; Sidewalks; Steps; Concrete Hotbeds
+    and Cold Frames; Concrete Slab Roofs; Walls for Buildings;
+    Repairing Leaks in Tanks and Cisterns; and all topics associated
+    with these subjects as bearing upon securing the best results
+    from concrete are dwelt upon at sufficient length in plain
+    every-day English so that the inexperienced person desiring to
+    undertake a piece of concrete construction can, by following the
+    directions set forth in this book, secure 100 per cent. success
+    every time. A number of convenient and practical tables for
+    estimating quantities, and some practical examples, are also
+    given. (5x7.) 149 pages. 51 illustrations. Price =75 cents=
+
+
+=Popular Handbook for Cement and Concrete Users.= By MYRON H. LEWIS.
+
+    This is a concise treatise of the principles and methods
+    employed in the manufacture and use of cement in all classes of
+    modern works. The author has brought together in this work all
+    the salient matter of interest to the user of concrete and its
+    many diversified products. The matter is presented in logical
+    and systematic order, clearly written, fully illustrated and
+    free from involved mathematics. Everything of value to the
+    concrete user is given, including kinds of cement employed in
+    construction, concrete architecture, inspection and testing,
+    waterproofing, coloring and painting, rules, tables, working and
+    cost data. The book comprises thirty-three chapters, as follow:
+    Introductory. Kinds of Cement and How They are Made. Properties.
+    Testing and Requirements of Hydraulic Cement. Concrete and Its
+    Properties. Sand, Broken Stone and Gravel for Concrete. How to
+    Proportion the Materials. How to Mix and Place Concrete. Forms
+    of Concrete Construction. The Architectural and Artistic
+    Possibilities of Concrete. Concrete Residences. Mortars,
+    Plasters and Stucco, and How to Use Them. The Artistic Treatment
+    of Concrete Surfaces. Concrete Building Blocks. The Making of
+    Ornamental Concrete. Concrete Pipes, Fences, Posts, etc.
+    Essential Features and Advantages of Reenforced Concrete. How to
+    Design Reenforced Concrete Beams, Slabs and Columns.
+    Explanations of the Methods and Principles in Designing
+    Reenforced Concrete, Beams and Slabs. Systems of Reenforcement
+    Employed. Reenforced Concrete in Factory and General Building
+    Construction. Concrete in Foundation Work. Concrete Retaining
+    Walls, Abutments and Bulkheads. Concrete Arches and Arch
+    Bridges. Concrete Beam and Girder Bridges. Concrete in Sewerage
+    and Draining Works. Concrete Tanks, Dams and Reservoirs.
+    Concrete Sidewalks, Curbs and Pavements. Concrete in Railroad
+    Construction. The Utility of Concrete on the Farm. The
+    Waterproofing of Concrete Structures. Grout of Liquid Concrete
+    and Its Use. Inspection of Concrete Work. Cost of Concrete Work.
+    Some of the special features of the book are: 1.--The Attention
+    Paid to the Artistic and Architectural Side of Concrete Work.
+    2.--The Authoritative Treatment of the Problem of Waterproofing
+    Concrete. 3.--An Excellent Summary of the Rules to be Followed
+    in Concrete Construction. 4.--The Valuable Cost Data and Useful
+    Tables given. A valuable Addition to the Library of Every Cement
+    and Concrete User. Price =$2.50=
+
+    WHAT IS SAID OF THIS BOOK:
+
+    "The field of Concrete Construction is well covered and the
+    matter contained is well within the understanding of any
+    person."--_Engineering-Contracting._
+
+    "Should be on the bookshelves of every contractor, engineer, and
+    architect in the land."--_National Builder._
+
+
+=Waterproofing Concrete.= By MYRON H. LEWIS.
+
+    Modern Methods of Waterproofing Concrete and Other Structures. A
+    condensed statement of the Principles, Rules, and Precautions to
+    be Observed in Waterproofing and Dampproofing Structures and
+    Structural Materials. Paper binding. Illustrated. Price =50
+    cents=
+
+
+~DICTIONARIES~
+
+
+=Aviation Terms, Termes D'Aviation, English-French, French-English.=
+Compiled by Lieuts. VICTOR W. PAGÉ, A.S., S.C.U.S.R., and PAUL
+MONTARIOL, of the French Flying Corps, on duty on Signal Corps Aviation
+School, Mineola, L. I.
+
+    The lists contained are confined to essentials, and special
+    folding plates are included to show all important airplane
+    parts. The lists are divided in four sections as follows:
+    1.--Flying Field Terms. 2.--The Airplane. 3.--The Engine.
+    4.--Tools and Shop Terms.
+
+    A complete, well illustrated volume intended to facilitate
+    conversation between English-speaking and French aviators. A
+    very valuable book for all who are about to leave for duty
+    overseas.
+
+    Approved for publication by Major W. G. Kilner, S.C., U.S.C.O.
+    Signal Corps Aviation School, Hazelhurst Field, Mineola, L. I.
+    This book should be in every Aviator's and Mechanic's Kit for
+    ready reference. 128 pages, fully illustrated, with detailed
+    engravings. Price =$1.00=
+
+
+=Standard Electrical Dictionary.= By T. O'CONOR SLOANE.
+
+    An indispensable work to all interested in electrical science.
+    Suitable alike for the student and professional. A practical
+    handbook of reference containing definitions of about 5,000
+    distinct words, terms and phrases. The definitions are terse and
+    concise; and include every term used in electrical science.
+    Recently issued. An entirely new edition. Should be in the
+    possession of all who desire to keep abreast with the progress
+    of this branch of science. Complete, concise and convenient. 682
+    pages, 393 illustrations. Price =$3.00=
+
+
+~DIES--METAL WORK~
+
+
+=Dies: Their Construction and Use for the Modern Working of Sheet
+Metals.= By J. V. WOODWORTH.
+
+    A most useful book, and one which should be in the hands of all
+    engaged in the press working of metals; treating on the
+    Designing, Constructing, and Use of Tools, Fixtures and Devices,
+    together with the manner in which they should be used in the
+    Power Press, for the cheap and rapid production of the great
+    variety of sheet-metal articles now in use. It is designed as a
+    guide to the production of sheet-metal parts at the minimum of
+    cost with the maximum of output. The hardening and tempering of
+    Press tools and the classes of work which may be produced to the
+    best advantage by the use of dies in the power press are fully
+    treated. Its 515 illustrations show dies, press fixtures and
+    sheet-metal working devices, the descriptions of which are so
+    clear and practical that all metal-working mechanics will be
+    able to understand how to design, construct and use them. Many
+    of the dies and press fixtures treated were either constructed
+    by the author or under his supervision. Others were built by
+    skilful mechanics and are in use in large sheet-metal
+    establishments and machine shops. 6th Revised and Enlarged
+    Edition. Price =$3.00=
+
+
+=Punches, Dies and Tools for Manufacturing in Presses.= By J. V.
+WOODWORTH.
+
+    This work is a companion volume to the author's elementary work
+    entitled "Dies: Their Construction and Use." It does not go into
+    the details of die-making to the extent of the author's previous
+    book, but gives a comprehensive review of the field of
+    operations carried on by presses. A large part of the
+    information given has been drawn from the author's personal
+    experience. It might well be termed an Encyclopedia of
+    Die-Making, Punch-Making, Die-Sinking, Sheet-Metal Working, and
+    Making of Special Tools, Sub-presses, Devices and Mechanical
+    Combinations for Punching, Cutting, Bending, Forming, Piercing,
+    Drawing, Compressing and Assembling Sheet-Metal Parts, and also
+    Articles of other Materials in Machine Tools. 2d Edition. Price
+    =$4.00=
+
+
+=Drop Forging, Die-Sinking and Machine-Forming of Steel.= By J. V.
+WOODWORTH.
+
+    This is a practical treatise on Modern Shop Practice, Processes,
+    Methods, Machine Tools, and Details treating on the Hot and Cold
+    Machine-Forming of Steel and Iron into Finished Shapes: together
+    with Tools, Dies, and Machinery involved in the manufacture of
+    Duplicate Forgings and Interchangeable Hot and Cold Pressed
+    Parts from Bar and Sheet Metal. This book fills a demand of long
+    standing for information regarding drop-forgings, die-sinking
+    and machine-forming of steel and the shop practice involved, as
+    it actually exists in the modern drop-forging shop. The
+    processes of die-sinking and force-making, which are thoroughly
+    described and illustrated in this admirable work, are rarely to
+    be found explained in such a clear and concise manner as is here
+    set forth. The process of die-sinking relates to the engraving
+    or sinking of the female or lower dies, such as are used for
+    drop-forgings, hot and cold machine-forging, swedging, and the
+    press working of metals. The process of force-making relates to
+    the engraving or raising of the male or upper dies used in
+    producing the lower dies for the press-forming and
+    machine-forging of duplicate parts of metal.
+
+    In addition to the arts above mentioned the book contains
+    explicit information regarding the drop-forging and hardening
+    plants, designs, conditions, equipment, drop hammers, forging
+    machines, etc., machine forging, hydraulic forging, autogenous
+    welding and shop practice. The book contains eleven chapters,
+    and the information contained in these chapters is just what
+    will prove most valuable to the forged-metal worker. All
+    operations described in the work are thoroughly illustrated by
+    means of perspective half-tones and outline sketches of the
+    machinery employed. 300 detailed illustrations. Price =$2.50=
+
+
+~DRAWING--SKETCHING PAPER~
+
+
+=Practical Perspective.= By RICHARDS and COLVIN.
+
+    Shows just how to make all kinds of mechanical drawings in the
+    only practical perspective isometric. Makes everything plain, so
+    that any mechanic can understand a sketch or drawing in this
+    way. Saves time in the drawing room, and mistakes in the shops.
+    Contains practical examples of various classes of work. 4th
+    Edition. Price =50 cents=
+
+
+=Linear Perspective Self-Taught.= By HERMAN T. C. KRAUS.
+
+    This work gives the theory and practice of linear perspective,
+    as used in architectural, engineering and mechanical drawings.
+    Persons taking up the study of the subject by themselves will be
+    able, by the use of the instruction given, to readily grasp the
+    subject, and by reasonable practice become good perspective
+    draftsmen. The arrangement of the book is good; the plate is on
+    the left-hand, while the descriptive text follows on the
+    opposite page, so as to be readily referred to. The drawings are
+    on sufficiently large scale to show the work clearly and are
+    plainly figured. There is included a self-explanatory chart
+    which gives all information necessary for the thorough
+    understanding of perspective. This chart alone is worth many
+    times over the price of the book. 2d Revised and Enlarged
+    Edition. Price =$2.50=
+
+
+=Self-Taught Mechanical Drawing and Elementary Machine Design.= By F. L.
+SYLVESTER, M.E., Draftsman, with additions by ERIK OBERG, associate
+editor of "Machinery."
+
+    This is a practical treatise on Mechanical Drawing and Machine
+    Design, comprising the first principles of geometric and
+    mechanical drawing, workshop mathematics, mechanics, strength of
+    materials and the calculations and design of machine details.
+    The author's aim has been to adapt this treatise to the
+    requirements of the practical mechanic and young draftsman and
+    to present the matter in as clear and concise a manner as
+    possible. To meet the demands of this class of students,
+    practically all the important elements of machine design have
+    been dealt with, and in addition algebraic formulas have been
+    explained, and the elements of trigonometry treated in the
+    manner best suited to the needs of the practical man. The book
+    is divided into 20 chapters, and in arranging the material,
+    mechanical drawing, pure and simple, has been taken up first, as
+    a thorough understanding of the principles of representing
+    objects facilitates the further study of mechanical subjects.
+    This is followed by the mathematics necessary for the solution
+    of the problems in machine design which are presented later, and
+    a practical introduction to theoretical mechanics and the
+    strength of materials. The various elements entering into
+    machine design, such as cams, gears, sprocket-wheels, cone
+    pulleys, bolts, screws, couplings, clutches, shafting and
+    fly-wheels, have been treated in such a way as to make possible
+    the use of the work as a text-book for a continuous course of
+    study. It is easily comprehended and assimilated even by
+    students of limited previous training. 330 pages, 215
+    engravings. Price =$2.00=
+
+
+=A New Sketching Paper.=
+
+    A new specially ruled paper to enable you to make sketches or
+    drawings in isometric perspective without any figuring or
+    fussing. It is being used for shop details as well as for
+    assembly drawings, as it makes one sketch do the work of three,
+    and no workman can help seeing just what is wanted.
+
+    Pads of 40 sheets, 6x9 inches.    Price     =25 cents=
+    Pads of 40 sheets, 9x12 inches.   Price     =50 cents=
+    40 sheets, 12x18 inches.          Price        =$1.00=
+
+
+~ELECTRICITY~
+
+
+=Arithmetic of Electricity.= By Prof. T. O'CONOR SLOANE.
+
+    A practical treatise on electrical calculations of all kinds
+    reduced to a series of rules, all of the simplest forms, and
+    involving only ordinary arithmetic; each rule illustrated by one
+    or more practical problems, with detailed solution of each one.
+    This book is classed among the most useful works published on
+    the science of electricity, covering as it does the mathematics
+    of electricity in a manner that will attract the attention of
+    those who are not familiar with algebraical formulas. 20th
+    Edition. 160 pages. Price =$1.00=
+
+
+=Commutator Construction.= By WM. BAXTER, JR.
+
+    The business end of any dynamo or motor of the direct current
+    type is the commutator. This book goes into the designing,
+    building, and maintenance of commutators, shows how to locate
+    troubles and how to remedy them; everyone who fusses with
+    dynamos needs this. 4th Edition. Price =25 cents=
+
+
+=Dynamo Building for Amateurs, or How to Construct a Fifty-Watt Dynamo.=
+By ARTHUR J. WEED, Member of N. Y. Electrical Society.
+
+    A practical treatise showing in detail the construction of a
+    small dynamo or motor, the entire machine work of which can be
+    done on a small foot lathe. Dimensioned working drawings are
+    given for each piece of machine work, and each operation is
+    clearly described. This machine, when used as a dynamo, has an
+    output of fifty watts; when used as a motor it will drive a
+    small drill press or lathe. It can be used to drive a sewing
+    machine on any and all ordinary work. The book is illustrated
+    with more than sixty original engravings, showing the actual
+    construction of the different parts. Among the contents are
+    chapters on: 1. Fifty-Watt Dynamo. 2. Side Bearing Rods. 3.
+    Field Punching. 4. Bearings. 5. Commutator. 6. Pulley. 7. Brush
+    Holders. 8. Connection Board. 9. Armature Shaft. 10. Armature.
+    11. Armature Winding. 12. Field Winding. 13. Connecting and
+    starting.
+
+    Paper.   Price     =50 Cents=
+    Cloth.   Price        =$1.00=
+
+
+=Electric Bells.= By M. B. SLEEPER.
+
+    A complete treatise for the practical worker in Installing,
+    Operating and Testing Bell Circuits, Burglar Alarms,
+    Thermostats, and other apparatus used with Electric Bells.
+
+    Both the electrician and the experimenter will find in this book
+    new material which is essential in their work. Tools, bells,
+    batteries, unusual circuits, burglar alarms, annunciator
+    systems, thermostats, circuit breakers, time alarms, and other
+    apparatus used in bell circuits are described from the
+    standpoints of their application, construction and repair. The
+    detailed instruction for building the apparatus will appeal to
+    the experimenter particularly.
+
+    The practical worker will find the chapter on Wiring,
+    Calculation of Wire Sizes and Magnet Winding, Upkeep of Systems,
+    and the Location of Faults, of the greatest value in their work.
+    Among the chapters are: Tools and Materials for Bell Work; How
+    and Why Bell Work; Batteries for Small Installations; Making
+    Bells and Push Buttons; Wiring Bell Systems; Construction of
+    Annunciators and Signals; Burglary Alarms and Auxiliary
+    Apparatus; More Elaborate Bell Systems; Finding Faults and
+    Remedying Them. 124 pages, fully illustrated. Price =50 cents=
+
+
+=Electric Lighting and Heating Pocket Book.= By SYDNEY F. WALKER.
+
+    This book puts in convenient form useful information regarding
+    the apparatus which is likely to be attached to the mains of an
+    electrical company. Tables of units and equivalents are included
+    and useful electrical laws and formulas are stated. 438 pages,
+    300 engravings. Bound in leather. Pocket book form. Price
+    =$3.00=
+
+
+=Electric Wiring, Diagrams and Switchboards.= By NEWTON HARRISON, with
+additions by THOMAS POPPE.
+
+    A thoroughly practical treatise covering the subject of Electric
+    Wiring in all its branches, deluding explanations and diagrams
+    which are thoroughly explicit and greatly simplify the subject.
+    Practical every-day problems in wiring are presented and the
+    method of obtaining intelligent results clearly shown. Only
+    arithmetic is used. Ohm's law is given a simple explanation with
+    reference to wiring for direct and alternating currents. The
+    fundamental principle of drop of potential in circuits is shown
+    with its various applications. The simple circuit is developed
+    with the position of mains, feeders and branches; their
+    treatment as a part of a wiring plan and their employment in
+    house wiring clearly illustrated. Some simple facts about
+    testing are included in connection with the wiring. Molding and
+    conduit work are given careful consideration; and switchboards
+    are systematically treated, built up and illustrated, showing
+    the purpose they serve, for connection with the circuits, and to
+    shunt and compound wound machines. The simple principles of
+    switchboard construction, the development of the switchboard,
+    the connections of the various instruments, including the
+    lightning arrester, are also plainly set forth.
+
+    Alternating current wiring is treated, with explanations of the
+    power factor, conditions calling for various sizes of wire, and
+    a simple way of obtaining the sizes for single-phase, two-phase
+    and three-phase circuits. This is the only complete work issued
+    showing and telling you what you should know about direct and
+    alternating current wiring. It is a ready reference. The work is
+    free from advanced technicalities and mathematics, arithmetic
+    being used throughout. It is in every respect a handy,
+    well-written, instructive, comprehensive volume on wiring for
+    the wireman, foreman, contractor, or electrician. 2nd Revised
+    Edition. 303 pages, 130 illustrations. Price =$1.50=
+
+
+=Electric Furnaces and their Industrial Applications.= By J. WRIGHT.
+
+    This is a book which will prove of interest to many classes of
+    people: the manufacturer who desires to know what product can be
+    manufactured successfully in the electric furnace, the chemist
+    who wishes to post himself on the electro-chemistry, and the
+    student of science who merely looks into the subject from
+    curiosity. New, Revised and Enlarged Edition. 320 pages. Fully
+    illustrated, cloth. Price =$3.00=
+
+
+=Electric Toy Making, Dynamo Building, and Electric Motor Construction.=
+By Prof. T. O'CONOR SLOANE.
+
+    This work treats of the making at home of electrical toys,
+    electrical apparatus, motors, dynamos, and instruments in
+    general, and is designed to bring within the reach of young and
+    old the manufacture of genuine and useful electrical appliances.
+    The work is especially designed for amateurs and young folks.
+
+    Thousands of our young people are daily experimenting, and
+    busily engaged in making electrical toys and apparatus of
+    various kinds. The present work is just what is wanted to give
+    the much needed information in a plain, practical manner, with
+    illustrations to make easy the carrying out of the work. 20th
+    Edition. Price =$1.00=
+
+
+=Practical Electricity.= By Prof. T. O'CONOR SLOANE.
+
+    This work of 768 pages was previously known as Sloane's
+    Electricians' Hand Book, and is intended for the practical
+    electrician who has to make things go. The entire field of
+    electricity is covered within its pages. Among some of the
+    subjects treated are: The Theory of the Electric Current and
+    Circuit, Electro-Chemistry, Primary Batteries, Storage
+    Batteries, Generation and Utilization of Electric Powers,
+    Alternating Current, Armature Winding, Dynamos and Motors, Motor
+    Generators, Operation of the Central Station Switchboards,
+    Safety Appliances, Distribution of Electric Light and Power,
+    Street Mains, Transformers, Arc and Incandescent Lighting,
+    Electric Measurements, Photometry, Electric Railways, Telephony,
+    Bell-Wiring, Electric-Plating, Electric Heating, Wireless
+    Telegraphy, etc. It contains no useless theory; everything is to
+    the point. It teaches you just what you want to know about
+    electricity. It is the standard work published on the subject.
+    Forty-one chapters, 556 engravings. Price =$2.50=
+
+
+=Electricity Simplified.= By Prof. T. O'CONOR SLOANE.
+
+    The object of "Electricity Simplified" is to make the subject as
+    plain as possible and to show what the modern conception of
+    electricity is; to show how two plates of different metal,
+    immersed in acid, can send a message around the globe; to
+    explain how a bundle of copper wire rotated by a steam engine
+    can be the agent in lighting our streets; to tell what the volt,
+    ohm and ampere are, and what high and low tension mean; and to
+    answer the questions that perpetually arise in the mind in this
+    age of electricity. 13th Edition. 172 pages. Illustrated. Price
+    =$1.00=
+
+
+=House Wiring.= By THOMAS W. POPPE.
+
+    This work describes and illustrates the actual installation of
+    Electric Light Wiring, the manner in which the work should be
+    done, and the method of doing it. The book can be conveniently
+    carried in the pocket. It is intended for the Electrician,
+    Helper and Apprentice. It solves all Wiring Problems and
+    contains nothing that conflicts with the rulings of the National
+    Board of Fire Underwriters. It gives just the information
+    essential to the Successful Wiring of a Building. Among the
+    subjects treated are: Locating the Meter. Panel-Boards.
+    Switches. Plug Receptacles. Brackets. Ceiling Fixtures. The
+    Meter Connections. The Feed Wires. The Steel Armored Cable
+    System. The Flexible Steel Conduit System. The Ridig Conduit
+    System. A digest of the National Board of Fire Underwriters'
+    rules relating to metallic wiring systems. Various switching
+    arrangements explained and diagrammed. The easiest method of
+    testing the Three- and Four-way circuits explained. The
+    grounding of all metallic wiring systems and the reason for
+    doing so shown and explained. The insulation of the metal parts
+    of lamp fixtures and the reason for the same described and
+    illustrated. 125 pages. 2nd Edition, revised and enlarged. Fully
+    illustrated. Flexible cloth. Price =50 cents=
+
+
+=How to Become a Successful Electrician.= By Prof. T. O'CONOR SLOANE.
+
+    Every young man who wishes to become a successful electrician
+    should read this book. It tells in simple language the surest
+    and easiest way to become a successful electrician. The studies
+    to be followed, methods of work, field of operation and the
+    requirements of the successful electrician are pointed out and
+    fully explained. Every young engineer will find this an
+    excellent stepping stone to more advanced works on electricity
+    which he must master before success can be attained. Many young
+    men become discouraged at the very outstart by attempting to
+    read and study books that are far beyond their comprehension.
+    This book serves as the connecting link between the rudiments
+    taught in the public schools and the real study of electricity.
+    It is interesting from cover to cover. 18th Revised Edition,
+    just issued. 205 pages. Illustrated. Price =$1.00=
+
+
+=Management of Dynamos.= By LUMMIS-PATERSON.
+
+    A handbook of theory and practice. This work is arranged in
+    three parts. The first part covers the elementary theory of the
+    dynamo. The second part, the construction and action of the
+    different classes of dynamos in common use are described; while
+    the third part relates to such matters as affect the practical
+    management and working of dynamos and motors. 4th Edition. 292
+    pages, 117 illustrations. Price =$1.50=
+
+
+=Standard Electrical Dictionary.= By T. O'CONOR SLOANE.
+
+    An indispensable work to all interested in electrical science.
+    Suitable alike for the student and professional. A practical
+    handbook of reference containing definitions of about 5,000
+    distinct words, terms and phrases. The definitions are terse and
+    concise and include every term used in electrical science.
+    Recently issued. An entirely new edition. Should be in the
+    possession of all who desire to keep abreast with the progress
+    of this branch of science. In its arrangement and typography the
+    book is very convenient. The word or term defined is printed in
+    black-faced type, which readily catches the eye, while the body
+    of the page is in smaller but distinct type. The definitions are
+    well worded, and so as to be understood by the non-technical
+    reader. The general plan seems to be to give an exact, concise
+    definition, and then amplify and explain in a more popular way.
+    Synonyms are also given, and references to other words and
+    phrases are made. A very complete and accurate index of fifty
+    pages is at the end of the volume; and as this index contains
+    all synonyms, and as all phrases are indexed in every reasonable
+    combination of words, reference to the proper place in the body
+    of the book is readily made. It is difficult to decide how far a
+    book of this character is to keep the dictionary form, and to
+    what extent it may assume the encyclopedia form. For some
+    purposes, concise, exactly worded definitions are needed; for
+    other purposes, more extended descriptions are required. This
+    book seeks to satisfy both demands, and does it with
+    considerable success. 682 pages, 393 illustrations. 12th
+    Edition. Price =$3.00=
+
+
+=Storage Batteries Simplified.= By VICTOR W. PAGÉ, M.E.
+
+    A complete treatise on storage battery operating principles,
+    repairs and applications. The greatly increasing application of
+    storage batteries in modern engineering and mechanical work has
+    created a demand for a book that will consider this subject
+    completely and exclusively. This is the most thorough and
+    authoritative treatise ever published on this subject. It is
+    written in easily understandable, non-technical language so that
+    any one may grasp the basic principles of storage battery action
+    as well as their practical industrial applications. All electric
+    and gasoline automobiles use storage batteries. Every automobile
+    repairman, dealer or salesman should have a good knowledge of
+    maintenance and repair of these important elements of the motor
+    car mechanism. This book not only tells how to charge, care for
+    and rebuild storage batteries but also outlines all the
+    industrial uses. Learn how they run street cars, locomotives and
+    factory trucks. Get an understanding of the important functions
+    they perform in submarine boats, isolated lighting plants,
+    railway switch and signal systems, marine applications, etc.
+    This book tells how they are used in central station standby
+    service, for starting automobile motors and in ignition systems.
+    Every practical use of the modern storage battery is outlined in
+    this treatise. 320 pages, fully illustrated. Price =$1.50=
+
+
+=Switchboards.= By WILLIAM BAXTER, JR.
+
+    This book appeals to every engineer and electrician who wants to
+    know the practical side of things. It takes up all sorts and
+    conditions of dynamos, connections and circuits, and shows by
+    diagram and illustration just how the switchboard should be
+    connected. Includes direct and alternating current boards, also
+    those for arc lighting, incandescent and power circuits. Special
+    treatment on high voltage boards for power transmission. 2nd
+    Edition. 190 pages, Illustrated. Price =$1.50=
+
+
+=Telephone Construction, Installation, Wiring, Operation and
+Maintenance.= By W. H. RADCLIFFE and H. C. CUSHING.
+
+    This book is intended for the amateur, the wireman, or the
+    engineer who desires to establish a means of telephonic
+    communication between the rooms of his home, office, or shop. It
+    deals only with such things as may be of use to him rather than
+    with theories.
+
+    Gives the principles of construction and operation of both the
+    Bell and Independent instruments; approved methods of installing
+    and wiring them; the means of protecting them from lightning and
+    abnormal currents; their connection together for operation as
+    series or bridging stations; and rules for their inspection and
+    maintenance. Line wiring and the wiring and operation of special
+    telephone systems are also treated. Intricate mathematics are
+    avoided, and all apparatus, circuits and systems are thoroughly
+    described. The appendix contains definitions of units and terms
+    used in the text. Selected wiring tables, which are very
+    helpful, are also included. Among the subjects treated are
+    Construction, Operation, and Installation of Telephone
+    Instruments; Inspection and Maintenance of Telephone
+    Instruments; Telephone Line Wiring; Testing Telephone Line Wires
+    and Cables; Wiring and Operation of Special Telephone Systems,
+    etc. 2nd Edition, Revised and Enlarged. 223 pages, 154
+    illustrations. Price =$1.00=
+
+
+=Wireless Telegraphy and Telephony Simply Explained.= By ALFRED P.
+MORGAN.
+
+    This is undoubtedly one of the most complete and comprehensible
+    treatises on the subject ever published, and a close study of
+    its pages will enable one to master all the details of the
+    wireless transmission of messages. The author has filled a
+    long-felt want and has succeeded in furnishing a lucid,
+    comprehensible explanation in simple language of the theory and
+    practice of wireless telegraphy and telephony.
+
+    Among the contents are: Introductory; Wireless Transmission and
+    Reception--The Aerial System, Earth Connections--The
+    Transmitting Apparatus, Spark Coils and Transformers,
+    Condensers, Helixes, Spark Gaps, Anchor Gaps, Aerial
+    Switches--The Receiving Apparatus, Detectors, etc.--Tuning and
+    Coupling, Tuning Coils, Loose Couplers, Variable Condensers,
+    Directive Wave Systems--Miscellaneous Apparatus, Telephone
+    Receivers, Range of Stations, Static Interference--Wireless
+    Telephones, Sound and Sound Waves, The Vocal Cords and
+    Ear--Wireless Telephone, How Sounds Are Changed into Electric
+    Waves--Wireless Telephones, The Apparatus--Summary. 154 pages,
+    156 engravings. Price =$1.00=
+
+
+=Wiring a House.= By HERBERT PRATT.
+
+    Shows a house already built; tells just how to start about
+    wiring it; where to begin; what wire to use; how to run it
+    according to Insurance Rules; in fact, just the information you
+    need. Directions apply equally to a shop. 4th Edition. Price =25
+    cents=
+
+
+~FACTORY MANAGEMENT, ETC.~
+
+
+=Modern Machine Shop Construction, Equipment and Management.= By O. E.
+PERRIGO, M.E.
+
+    The only work published that describes the modern machine shop
+    or manufacturing plant from the time the grass is growing on the
+    site intended for it until the finished product is shipped. By a
+    careful study of its thirty-two chapters the practical man may
+    economically build, efficiently equip, and successfully manage
+    the modern machine shop or manufacturing establishment. Just the
+    book needed by those contemplating the erection of modern shop
+    buildings, the rebuilding and reorganization of old ones, or the
+    introduction of modern shop methods, time and cost systems. It
+    is a book written and illustrated by a practical shop man for
+    practical shop men who are too busy to read _theories_ and want
+    _facts_. It is the most complete all-around book of its kind
+    ever published. It is a practical book for practical men, from
+    the apprentice in the shop to the president in the office. It
+    minutely describes and illustrates the most simple and yet the
+    most efficient time and cost system yet devised. 2nd Revised and
+    Enlarged Edition, just issued. 384 pages, 219 illustrations.
+    Price =$5.00=
+
+
+~FUEL~
+
+
+=Combustion of Coal and the Prevention of Smoke.= By WM. M. BARR.
+
+    This book has been prepared with special reference to the
+    generation of heat by the combustion of the common fuels found
+    in the United States, and deals particularly with the conditions
+    necessary to the economic and smokeless combustion of bituminous
+    coals in Stationary and Locomotive Steam Boilers.
+
+    The presentation of this important subject is systematic and
+    progressive. The arrangement of the book is in a series of
+    practical questions to which are appended accurate answers,
+    which describe in language, free from technicalities, the
+    several processes involved in the furnace combustion of American
+    fuels; it clearly states the essential requisites for perfect
+    combustion, and points out the best methods for furnace
+    construction for obtaining the greatest quantity of heat from
+    any given quality of coal. Nearly 350 pages, fully illustrated.
+    Price =$1.00=
+
+
+=Smoke Prevention and Fuel Economy.= By BOOTH and KERSHAW.
+
+    A complete treatise for all interested in smoke prevention and
+    combustion, being based on the German work of Ernst Schmatolla,
+    but it is more than a mere translation of the German treatise,
+    much being added. The authors show as briefly as possible the
+    principles of fuel combustion, the methods which have been and
+    are at present in use, as well as the proper scientific methods
+    for obtaining all the energy in the coal and burning it without
+    smoke. Considerable space is also given to the examination of
+    the waste gases, and several of the representative English and
+    American mechanical stoker and similar appliances are described.
+    The losses carried away in the waste gases are thoroughly
+    analyzed and discussed in the Appendix, and abstracts are also
+    here given of various patents on combustion apparatus. The book
+    is complete and contains much of value to all who have charge of
+    large plants. 194 pages. Illustrated. Price =$2.50=
+
+
+~GAS ENGINES AND GAS~
+
+
+=Gas, Gasoline and Oil Engines.= By GARDNER D. HISCOX. Revised by VICTOR
+W. PAGÉ, M.E.
+
+    Just issued New 1918 Edition, Revised and Enlarged. Every user
+    of a gas engine needs this book. Simple, instructive and right
+    up-to-date. The only complete work on the subject. Tells all
+    about internal combustion engineering, treating exhaustively on
+    the design, construction and practical application of all forms
+    of gas, gasoline, kerosene and crude petroleum-oil engines.
+    Describes minutely all auxiliary systems, such as lubrication,
+    carburetion and ignition. Considers the theory and management of
+    all forms of explosive motors for stationary and marine work,
+    automobiles, aeroplanes and motor-cycles. Includes also Producer
+    Gas and Its Production. Invaluable instructions for all
+    students, gas-engine owners, gas-engineers, patent experts,
+    designers, mechanics, draftsmen and all having to do with the
+    modern power. Illustrated by over 400 engravings, many specially
+    made from engineering drawings, all in correct proportion. 650
+    pages, 435 engravings. Price =$2.50 net=
+
+
+=The Gasoline Engine on the Farm: Its Operation, Repair and Uses.= By
+XENO W. PUTNAM.
+
+    This is a practical treatise on the Gasoline and Kerosene Engine
+    intended for the man who wants to know just how to manage his
+    engine and how to apply it to all kinds of farm work to the best
+    advantage.
+
+    This book abounds with hints and helps for the farm and
+    suggestions for the home and house-wife. There is so much of
+    value in this book that it is impossible to adequately describe
+    it in such small space. Suffice to say that it is the kind of a
+    book every farmer will appreciate and every farm home ought to
+    have. Includes selecting the most suitable engine for farm work,
+    its most convenient and efficient installation, with chapters on
+    troubles, their remedies, and how to avoid them. The care and
+    management of the farm tractor in plowing, harrowing, harvesting
+    and road grading are fully covered; also plain directions are
+    given for handling the tractor on the road. Special attention is
+    given to relieving farm life of its drudgery by applying power
+    to the disagreeable small tasks which must otherwise be done by
+    hand. Many home made contrivances for cutting wood, supplying
+    kitchen, garden, and barn with water, loading, hauling and
+    unloading hay, delivering grain to the bins or the feed trough
+    are included; also full directions for making the engine milk
+    the cows, churn, wash, sweep the house and clean the windows,
+    etc. Very fully illustrated with drawings of working parts and
+    cuts showing Stationary, Portable and Tractor Engines doing all
+    kinds of farm work. All money-making farms utilize power. Learn
+    how to utilize power by reading the pages of this book. It is an
+    aid to the result getter, invaluable to the up-to-date farmer,
+    student, blacksmith, implement dealer and, in fact, all who can
+    apply practical knowledge of stationary gasoline engines or gas
+    tractors to advantage. 530 pages. Nearly 180 engravings. Price
+    =$2.00=
+
+    WHAT IS SAID OF THIS BOOK:
+
+    "Am much pleased with the book and find it to be very complete
+    and up-to-date. I will heartily recommend it to students and
+    farmers whom I think would stand in need of such a work, as I
+    think it is an exceptionally good one."--_N. S. Gardiner_, Prof.
+    in Charge, Clemson Agr. College of S. C.; Dept. of Agri. and
+    Agri. Exp. Station, Clemson College, S. C.
+
+    "I feel that Mr. Putnam's book covers the main points which a
+    farmer should know."--_R. T. Burdick_, Instructor in Agronomy,
+    University of Vermont, Burlington, Vt.
+
+
+=Gasoline Engines: Their Operation, Use and Care.= By A. HYATT VERRILL.
+
+    The simplest, latest and most comprehensive popular work
+    published on Gasoline Engines, describing what the Gasoline
+    Engine is; its construction and operation; how to install it;
+    how to select it; how to use it and how to remedy troubles
+    encountered. Intended for Owners, Operators and Users of
+    Gasoline Motors of all kinds. This work fully describes and
+    illustrates the various types of Gasoline Engines used in Motor
+    Boats, Motor Vehicles and Stationary Work. The parts,
+    accessories and appliances are described with chapters on
+    ignition, fuel, lubrication, operation and engine troubles.
+    Special attention is given to the care, operation and repair of
+    motors, with useful hints and suggestions on emergency repairs
+    and makeshifts. A complete glossary of technical terms and an
+    alphabetically arranged table of troubles and their symptoms
+    form most valuable and unique features of this manual. Nearly
+    every illustration in the book is original, having been made by
+    the author. Every page is full of interest and value. A book
+    which you cannot afford to be without. 275 pages, 152 specially
+    made engravings. Price =$1.50=
+
+
+=Gas Engine Construction, or How to Build a Half-horsepower Gas Engine.=
+By PARSELL and WEED.
+
+    A practical treatise of 300 pages describing the theory and
+    principles of the action of Gas Engines of various types and the
+    design and construction of a half-horsepower Gas Engine, with
+    illustrations of the work in actual progress, together with the
+    dimensioned working drawings, giving clearly the sizes of the
+    various details; for the student, the scientific investigator,
+    and the amateur mechanic. This book treats of the subject more
+    from the standpoint of practice than that of theory. The
+    principles of operation of Gas Engines are clearly and simply
+    described, and then the actual construction of a half-horsepower
+    engine is taken up, step by step, showing in detail the making
+    of the Gas Engine. 3rd Edition. 300 pages. Price =$2.50=
+
+
+=How to Run and Install Two- and Four-Cycle Marine Gasoline Engines.= By
+C. VON CULIN.
+
+    Revised and enlarged edition just issued. The object of this
+    little book is to furnish a pocket instructor for the beginner,
+    the busy man who uses an engine for pleasure or profit, but who
+    does not have the time or inclination for a technical book, but
+    simply to thoroughly understand how to properly operate, install
+    and care for his own engine. The index refers to each trouble,
+    remedy, and subject alphabetically. Being a quick reference to
+    find the cause, remedy and prevention for troubles, and to
+    become an expert with his own engine. Pocket size. Paper
+    binding. Price =25 cents=
+
+
+=Modern Gas Engines and Producer Gas Plants.= By R. E. MATHOT.
+
+    A guide for the gas engine designer, user, and engineer in the
+    construction, selection, purchase, installation, operation, and
+    maintenance of gas engines. More than one book on gas engines
+    has been written, but not one has thus far even encroached on
+    the field covered by this book. Above all, Mr. Mathot's work is
+    a practical guide. Recognizing the need of a volume that would
+    assist the gas engine user in understanding thoroughly the motor
+    upon which he depends for power, the author has discussed his
+    subject without the help of any mathematics and without
+    elaborate theoretical explanations. Every part of the gas engine
+    is described in detail, tersely, clearly, with a thorough
+    understanding of the requirements of the mechanic. Helpful
+    suggestions as to the purchase of an engine, its installation,
+    care, and operation, form a most valuable feature of the work.
+    320 pages, 175 detailed illustrations. Price =$2.50=
+
+
+=The Modern Gas Tractor.= By VICTOR W. PAGÉ, M. E.
+
+    A complete treatise describing all types and sizes of gasoline,
+    kerosene and oil tractors. Considers design and construction
+    exhaustively, gives complete instructions for care, operation
+    and repair, outlines all practical applications on the road and
+    in the field. The best and latest work on farm tractors and
+    tractor power plants. A work needed by farmers, students,
+    blacksmiths, mechanics, salesmen, implement dealers, designers
+    and engineers. 2nd Edition, Revised. 504 pages, 228
+    illustrations, 3 folding plates. Price =$2.00=
+
+
+~GEARING AND CAMS~
+
+
+=Bevel Gear Tables.= By D. AG. ENGSTROM.
+
+    A book that will at once commend itself to mechanics and
+    draftsmen. Does away with all the trigonometry and fancy
+    figuring on bevel gears, and makes it easy for anyone to lay
+    them out or make them just right. There are 36 full-page tables
+    that show every necessary dimension for all sizes or
+    combinations you're apt to need. No puzzling, figuring or
+    guessing. Gives placing distance, all the angles (including
+    cutting angles), and the correct cutter to use. A copy of this
+    prepares you for anything in the bevel-gear line. 3rd Edition.
+    66 pages. Price =$1.00=
+
+
+=Change Gear Devices.= By OSCAR E. PERRIGO.
+
+    A practical book for every designer, draftsman, and mechanic
+    interested in the invention and development of the devices for
+    feed changes on the different machines requiring such mechanism.
+    All the necessary information on this subject is taken up,
+    analyzed, classified, sifted, and concentrated for the use of
+    busy men who have not the time to go through the masses of
+    irrelevant matter with which such a subject is usually
+    encumbered and select such information as will be useful to
+    them.
+
+    It shows just what has been done, how it has been done, when it
+    was done, and who did it. It saves time in hunting up patent
+    records and re-inventing old ideas. 88 pages. 3rd Edition. Price
+    =$1.00=
+
+
+=Drafting of Cams.= By LOUIS ROUILLION.
+
+    The laying out of cams is a serious problem unless you know how
+    to go at it right. This puts you on the right road for
+    practically any kind of cam you are likely to run up against.
+    3rd Edition. Price =25 Cents=
+
+
+~HYDRAULICS~
+
+
+=Hydraulic Engineering.= By GARDNER D. HISCOX.
+
+    A treatise on the properties, power, and resources of water for
+    all purposes. Including the measurement of streams, the flow of
+    water in pipes or conduits; the horsepower of falling water,
+    turbine and impact water-wheels, wave motors, centrifugal,
+    reciprocating and air-lift pumps. With 300 figures and diagrams
+    and 36 practical tables. All who are interested in water-works
+    development will find this book a useful one, because it is an
+    entirely practical treatise upon a subject of present importance
+    and cannot fail in having a far-reaching influence, and for this
+    reason should have a place in the working library of every
+    engineer. Among the subjects treated are: Historical Hydraulics;
+    Properties of Water; Measurement of the Flow of Streams; Flow
+    from Sub-surface Orifices and Nozzles; Flow of Water in Pipes;
+    Siphons of Various Kinds; Dams and Great Storage Reservoirs;
+    City and Town Water Supply; Wells and Their Reinforcement;
+    Air-lift Methods of Raising Water; Artesian Wells; Irrigation of
+    Arid Districts; Water Power; Water Wheels; Pumps and Pumping
+    Machinery; Reciprocating Pumps; Hydraulic Power Transmission;
+    Hydraulic Mining; Canals; Ditches; Conduits and Pipe Lines;
+    Marine Hydraulics; Tidal and Sea Wave Power, etc. 320 pages.
+    Price =$4.00=
+
+
+~ICE AND REFRIGERATION~
+
+
+=Pocketbook of Refrigeration and Ice Making.= By A. J. WALLIS-TAYLOR.
+
+    This is one of the latest and most comprehensive reference books
+    published on the subject of refrigeration and cold storage. It
+    explains the properties and refrigerating effect of the
+    different fluids in use, the management of refrigerating
+    machinery and the construction and insulation of cold rooms with
+    their required pipe surface for different degrees of cold;
+    freezing mixtures and non-freezing brines, temperatures of cold
+    rooms for all kinds of provisions, cold storage charges for all
+    classes of goods, ice making and storage of ice, data and
+    memoranda for constant reference by refrigerating engineers,
+    with nearly one hundred tables containing valuable references to
+    every fact and condition required in the installment and
+    operation of a refrigerating plant. New edition just published.
+    Price =$1.50=
+
+
+~INVENTIONS--PATENTS~
+
+
+=Inventors' Manual: How to Make a Patent Pay.=
+
+    This is a book designed as a guide to inventors in perfecting
+    their inventions, taking out their patents and disposing of
+    them. It is not in any sense a Patent Solicitor's Circular nor a
+    Patent Broker's Advertisement. No advertisements of any
+    description appear in the work. It is a book containing a
+    quarter of a century's experience of a successful inventor,
+    together with notes based upon the experience of many other
+    inventors.
+
+    Among the subjects treated in this work are: How to Invent. How
+    to Secure a Good Patent. Value of Good Invention. How to Exhibit
+    an Invention. How to Interest Capital. How to Estimate the Value
+    of a Patent. Value of Design Patents. Value of Foreign Patents.
+    Value of Small Inventions. Advice on Selling Patents. Advice on
+    the Formation of Stock Companies. Advice on the Formation of
+    Limited Liability Companies. Advice on Disposing of Old Patents.
+    Advice as to Patent Attorneys. Advice as to Selling Agents.
+    Forms of Assignments. License and Contracts. State Laws
+    Concerning Patent Rights. 1900 Census of the United States by
+    Counts of Over 10,000 Population. Revised Edition. 120 pages.
+    Price =$1.00=
+
+
+~KNOTS~
+
+
+=Knots, Splices and Rope Work.= By A. HYATT VERRILL.
+
+    This is a practical book giving complete and simple directions
+    for making all the most useful and ornamental knots in common
+    use, with chapters on Splicing, Pointing, Seizing, Serving, etc.
+    This book is fully illustrated with 154 original engravings,
+    which show how each knot, tie or splice is formed, and its
+    appearance when finished. The book will be found of the greatest
+    value to Campers, Yachtsmen, Travelers, Boy Scouts, in fact, to
+    anyone having occasion to use or handle rope or knots for any
+    purpose. The book is thoroughly reliable and practical, and is
+    not only a guide, but a teacher. It is the standard work on the
+    subject. Among the contents are: 1. Cordage, Kinds of Rope.
+    Construction of Rope, Parts of Rope Cable and Bolt Rope.
+    Strength of Rope, Weight of Rope. 2. Simple Knots and Bends.
+    Terms Used in Handling Rope. Seizing Rope. 3. Ties and Hitches.
+    4. Noose, Loops and Mooring Knots. 5. Shortenings, Grommets and
+    Salvages. 6. Lashings, Seizings and Splices. 7. Fancy Knots and
+    Rope Work. 128 pages, 150 original engravings. 2nd Revised
+    Edition. Price =75 cents=
+
+
+~LATHE WORK~
+
+
+=Lathe Design, Construction, and Operation, with Practical Examples of
+Lathe Work.= By OSCAR E. PERRIGO.
+
+    A new, revised edition, and the only complete American work on
+    the subject, written by a man who knows not only how work ought
+    to be done, but who also knows how to do it, and how to convey
+    this knowledge to others. It is strictly up-to-date in its
+    descriptions and illustrations. Lathe history and the relations
+    of the lathe to manufacturing are given; also a description of
+    the various devices for feeds and thread-cutting mechanisms from
+    early efforts in this direction to the present time. Lathe
+    design is thoroughly discussed, including back gearing, driving
+    cones, thread-cutting gears, and all the essential elements of
+    the modern lathe. The classification of lathes is taken up,
+    giving the essential differences of the several types of lathes
+    including, as is usually understood, engine lathes, bench
+    lathes, speed lathes, forge lathes, gap lathes, pulley lathes,
+    forming lathes, multiple-spindle lathes, rapid-reduction lathes,
+    precision lathes, turret lathes, special lathes, electrically
+    driven lathes, etc. In addition to the complete exposition on
+    construction and design, much practical matter on lathe
+    installation, care and operation has been incorporated in the
+    enlarged new edition. All kinds of lathe attachments for
+    drilling, milling, etc., are described and complete instructions
+    are given to enable the novice machinist to grasp the art of
+    lathe operation as well as the principles involved in design. A
+    number of difficult machining operations are described at length
+    and illustrated. The new edition has nearly 500 pages and 350
+    illustrations. Price =$2.50=
+
+    WHAT IS SAID OF THIS BOOK:
+
+    "This is a lathe book from beginning to end, and is just the
+    kind of a book which one delights to consult--a masterly
+    treatment of the subject in hand."--_Engineering News._
+
+    "This work will be of exceptional interest to any one who is
+    interested in lathe practice, as one very seldom sees such a
+    complete treatise on a subject as this is on the
+    lathe."--_Canadian Machinery._
+
+
+=Practical Metal Turning.= By JOSEPH G. HORNER.
+
+    A work of 404 pages, fully illustrated, covering in a
+    comprehensive manner the modern practice of machining metal
+    parts in the lathe, including the regular engine lathe, its
+    essential design, its uses, its tools, its attachments, and the
+    manner of holding the work and performing the operations. The
+    modernized engine lathe, its methods, tools and great range of
+    accurate work. The turret lathe, its tools, accessories and
+    methods of performing its functions. Chapters on special work,
+    grinding, tool holders, speeds, feeds, modern tool steels, etc.
+    Second edition =$3.50=
+
+
+=Turning and Boring Tapers.= By FRED H. COLVIN.
+
+    There are two ways to turn tapers; the right way and one other.
+    This treatise has to do with the right way; it tells you how to
+    start the work properly, how to set the lathe, what tools to use
+    and how to use them, and forty and one other little things that
+    you should know. Fourth edition =25 cents=
+
+
+~LIQUID AIR~
+
+
+=Liquid Air and the Liquefaction of Gases.= By T. O'CONOR SLOANE.
+
+    This book gives the history of the theory, discovery and
+    manufacture of Liquid Air, and contains an illustrated
+    description of all the experiments that have excited the wonder
+    of audiences all over the country. It shows how liquid air, like
+    water, is carried hundreds of miles and is handled in open
+    buckets. It tells what may be expected from it in the near
+    future.
+
+    A book that renders simple one of the most perplexing chemical
+    problems of the century. Startling developments illustrated by
+    actual experiments.
+
+    It is not only a work of scientific interest and authority, but
+    is intended for the general reader, being written in a popular
+    style--easily understood by every one. Second edition. 365
+    pages. Price =$2.00=
+
+
+~LOCOMOTIVE ENGINEERING~
+
+
+=Air-Brake Catechism.= By ROBERT H. BLACKALL.
+
+    This book is a standard text-book. It covers the Westinghouse
+    Air-Brake Equipment, including the No. 5 and the No. 6 E.-T.
+    Locomotive Brake Equipment; the K (Quick Service) Triple Valve
+    for Freight Service; and the Cross-Compound Pump. The operation
+    of all parts of the apparatus is explained in detail, and a
+    practical way of finding their peculiarities and defects, with a
+    proper remedy, is given. It contains 2,000 questions with their
+    answers, which will enable any railroad man to pass any
+    examination on the subject of Air Brakes. Endorsed and used by
+    air-brake instructors and examiners on nearly every railroad in
+    the United States. Twenty-sixth edition. 411 pages, fully
+    illustrated with colored plates and diagrams. Price =$2.00=
+
+
+=American Compound Locomotives.= By FRED H. COLVIN.
+
+    The only book on compounds for the engineman or shopman that
+    shows in a plain, practical way the various features of compound
+    locomotives in use. Shows how they are made, what to do when
+    they break down or balk. Contains sections as follows: A Bit of
+    History. Theory of Compounding Steam Cylinders. Baldwin
+    Two-Cylinder Compound. Pittsburg Two-Cylinder Compound. Rhode
+    Island Compound. Richmond Compound. Rogers Compound. Schenectady
+    Two-Cylinder Compound. Vauclain Compound. Tandem Compounds.
+    Baldwin Tandem. The Colvin-Wightman Tandem. Schenectady Tandem.
+    Balanced Locomotives. Baldwin Balanced Compound. Plans for
+    Balancing. Locating Blows. Breakdowns. Reducing Valves.
+    Drifting. Valve Motion. Disconnecting. Power of Compound
+    Locomotives. Practical Notes.
+
+    Fully illustrated and containing ten special "Duotone" inserts
+    on heavy Plate Paper, showing different types of Compounds. 142
+    pages. Price =$1.00=
+
+
+=Application of Highly Superheated Steam to Locomotives.= By ROBERT
+GARBE.
+
+    A practical book which cannot be recommended too highly to those
+    motive-power men who are anxious to maintain the highest
+    efficiency in their locomotives. Contains special chapters on
+    Generation of Highly Superheated Steam; Superheated Steam and
+    the Two-Cylinder Simple Engine; Compounding and Superheating;
+    Designs of Locomotive Superheaters; Constructive Details of
+    Locomotives Using Highly Superheated Steam. Experimental and
+    Working Results. Illustrated with folding plates and tables.
+    Cloth. Price =$2.50=
+
+
+=Combustion of Coal and the Prevention of Smoke.= By WM. M. BARR.
+
+    This book has been prepared with special reference to the
+    generation of heat by the combustion of the common fuels found
+    in the United States and deals particularly with the conditions
+    necessary to the economic and smokeless combustion of bituminous
+    coal in Stationary and Locomotive Steam Boilers.
+
+    Presentation of this important subject is systematic and
+    progressive. The arrangement of the book is in a series of
+    practical questions to which are appended accurate answers,
+    which describe in language free from technicalities the several
+    processes involved in the furnace combustion of American fuels;
+    it clearly states the essential requisites for perfect
+    combustion, and points out the best methods of furnace
+    construction for obtaining the greatest quantity of heat from
+    any given quality of coal. Nearly 350 pages, fully illustrated.
+    Price =$1.00=
+
+
+=Diary of a Round-House Foreman.= By T. S. REILLY.
+
+    This is the greatest book of railroad experiences ever
+    published. Containing a fund of information and suggestions
+    along the line of handling men, organizing, etc., that one
+    cannot afford to miss. 176 pages. Price =$1.00=
+
+
+=Link Motions, Valves and Valve Setting.= By FRED H. COLVIN, Associate
+Editor of "American Machinist."
+
+    A handy book for the engineer or machinist that clears up the
+    mysteries of valve setting. Shows the different valve gears in
+    use, how they work, and why. Piston and slide valves of
+    different types are illustrated and explained. A book that every
+    railroad man in the motive-power department ought to have.
+    Contains chapters on Locomotive Link Motion, Valve Movements,
+    Setting Slide Valves, Analysis by Diagrams, Modern Practice,
+    Slip of Block, Slice Valves, Piston Valves, Setting Piston
+    Valves, Joy-Allen Valve Gear, Walschaert Valve Gear, Gooch Valve
+    Gear, Alfree-Hubbell Valve Gear, etc., etc. Fully illustrated.
+    Price =50 cents=
+
+
+=Locomotive Boiler Construction.= By FRANK A. KLEINHANS.
+
+    The construction of boilers in general is treated and, following
+    this, the locomotive boiler is taken up in the order in which
+    its various parts go through the shop. Shows all types of
+    boilers used; gives details of construction; practical facts,
+    such as life of riveting, punches and dies; work done per day,
+    allowance for bending and flanging sheets and other data.
+    Including the recent Locomotive Boiler Inspection Laws and
+    Examination Questions with their answers for Government
+    Inspectors. Contains chapters on Laying-Out Work; Flanging and
+    Forging; Punching; Shearing; Plate Planing; General Tables;
+    Finishing Parts; Bending; Machinery Parts; Riveting; Boiler
+    Details; Smoke-Box Details; Assembling and Calking; Boiler-Shop
+    Machinery, etc., etc.
+
+    There isn't a man who has anything to do with boiler work,
+    either new or repair work, who doesn't need this book. The
+    manufacturer, superintendent, foreman and boiler worker--all
+    need it. No matter what the type of boiler, you'll find a mint
+    of information that you wouldn't be without. Over 400 pages,
+    five large folding plates. Price =$3.00=
+
+
+=Locomotive Breakdowns and their Remedies.= By GEO. L. FOWLER. Revised
+by WM. W. WOOD, Air-Brake Instructor. Just issued. Revised pocket
+edition.
+
+    It is out of the question to try and tell you about every
+    subject that is covered in this pocket edition of Locomotive
+    Breakdowns. Just imagine all the common troubles that an
+    engineer may expect to happen some time, and then add all of the
+    unexpected ones, troubles that could occur, but that you have
+    never thought about, and you will find that they are all treated
+    with the very best methods of repair. Walschaert Locomotive
+    Valve Gear Troubles, Electric Headlight Troubles, as well as
+    Questions and Answers on the Air Brake are all included. 312
+    pages. 8th Revised Edition. Fully illustrated. Price =$1.00=
+
+
+=Locomotive Catechism.= By ROBERT GRIMSHAW.
+
+    The revised edition of "Locomotive Catechism," by Robert
+    Grimshaw, is a New Book from Cover to Cover. It contains twice
+    as many pages and double the number of illustrations of previous
+    editions. Includes the greatest amount of practical information
+    ever published on the construction and management of modern
+    locomotives. Specially Prepared Chapters on the Walschaert
+    Locomotive Valve Gear, the Air-Brake Equipment and the Electric
+    Headlight are given.
+
+    It commends itself at once to every Engineer and Fireman, and to
+    all who are going in for examination or promotion. In plain
+    language, with full, complete answers, not only all the
+    questions asked by the examining engineer are given, but those
+    which the young and less experienced would ask the veteran, and
+    which old hands ask as "stickers." It is a veritable
+    Encyclopedia of the Locomotive, is entirely free from
+    mathematics, easily understood and thoroughly up to date.
+    Contains over 4,000 Examination Questions with their Answers.
+    825 pages, 437 illustrations, and 3 folding plates. 28th Revised
+    Edition. Price =$2.50=
+
+
+=Practical Instructor and Reference Book for Locomotive Firemen and
+Engineers.= By CHAS. F. LOCKHART.
+
+    An entirely new book on the Locomotive. It appeals to every
+    railroad man, as it tells him how things are done and the right
+    way to do them. Written by a man who has had years of practical
+    experience in locomotive shops and on the road firing and
+    running. The information given in this book cannot be found in
+    any other similar treatise. Eight hundred and fifty-one
+    questions with their answers are included, which will prove
+    specially helpful to those preparing for examination. Practical
+    information on: The Construction and Operation of Locomotives,
+    Breakdowns and their Remedies, Air Brakes and Valve Gears. Rules
+    and Signals are handled in a thorough manner. As a book of
+    reference it cannot be excelled. The book is divided into six
+    parts, as follows: 1. The Fireman's Duties. 2. General
+    Description of the Locomotive. 3. Breakdowns and their Remedies.
+    4. Air Brakes. 5. Extracts from Standard Rules. 6. Questions for
+    Examination. The 851 questions have been carefully selected and
+    arranged. These cover the examinations required by the different
+    railroads. 368 pages, 88 illustrations. Price =$1.50=
+
+
+=Prevention of Railroad Accidents, or Safety in Railroading.= By GEORGE
+BRADSHAW.
+
+    This book is a heart-to-heart talk with Railroad Employees,
+    dealing with facts, not theories, and showing the men in the
+    ranks, from every-day experience, how accidents occur and how
+    they may be avoided. The book is illustrated with seventy
+    original photographs and drawings showing the safe and unsafe
+    methods of work. No visionary schemes, no ideal pictures. Just
+    Plain Facts and Practical Suggestions are given. Every railroad
+    employee who reads the book is a better and safer man to have in
+    railroad service. It gives just the information which will be
+    the means of preventing many injuries and deaths. All railroad
+    employees should procure a copy, read it, and do their part in
+    preventing accidents. 169 pages. Pocket size. Fully illustrated.
+    Price =50 cents=
+
+
+=Train Rule Examinations Made Easy.= By G. E. COLLINGWOOD.
+
+    This is the only practical work on train rules in print. Every
+    detail is covered, and puzzling points are explained in simple,
+    comprehensive language, making it a practical treatise for the
+    Train Dispatcher, Engineman, Trainman, and all others who have
+    to do with the movements of trains. Contains complete and
+    reliable information of the Standard Code of Train Rules for
+    single track. Shows Signals in Colors, as used on the different
+    roads. Explains fully the practical application of train orders,
+    giving a clear and definite understanding of all orders which
+    may be used. The meaning and necessity for certain rules are
+    explained in such a manner that the student may know beyond a
+    doubt the rights conferred under any orders he may receive or
+    the action required by certain rules. As nearly all roads
+    require trainmen to pass regular examinations, a complete set of
+    examination questions, with their answers, are included. These
+    will enable the student to pass the required examinations with
+    credit to himself and the road for which he works. 2nd Edition,
+    Revised. 256 pages, fully illustrated, with Train Signals in
+    Colors. Price =$1.25=
+
+
+=The Walschaert and Other Modern Radial Valve Gears for Locomotives.= By
+WM. W. WOOD.
+
+    If you would thoroughly understand the Walschaert Valve Gear you
+    should possess a copy of this book, as the author takes the
+    plainest form of a steam engine--a stationary engine in the
+    rough, that will only turn its crank in one direction--and from
+    it builds up, with the reader's help, a modern locomotive
+    equipped with the Walschaert Valve Gear, complete. The points
+    discussed are clearly illustrated: Two large folding plates that
+    show the positions of the valves of both inside or outside
+    admission type, as well as the links and other parts of the gear
+    when the crank is at nine different points in its revolution,
+    are especially valuable in making the movement clear. These
+    employ sliding cardboard models which are contained in a pocket
+    in the cover.
+
+    The book is divided into five general divisions, as follows: 1.
+    Analysis of the gear. 2. Designing and erecting the gear. 3.
+    Advantages of the gear. 4. Questions and answers relating to the
+    Walschaert Valve Gear. 5. Setting valves with the Walschaert
+    Valve Gear; the three primary types of locomotive valve motion;
+    modern radial valve gears other than the Walschaert; the Hobart
+    All-free Valve and Valve Gear, with questions and answers on
+    breakdowns; the Baker-Pilliod Valve Gear; the Improved
+    Baker-Pilliod Valve Gear, with questions and answers on
+    breakdowns.
+
+    The questions with full answers given will be especially
+    valuable to firemen and engineers in preparing for an
+    examination for promotion. 245 pages. 3rd Revised Edition. Price
+    =$1.50=
+
+
+=Westinghouse E-T Air-Brake Instruction Pocket Book.= By WM. W. WOOD,
+Air-Brake Instructor.
+
+    Here is a book for the railroad man, and the man who aims to be
+    one. It is without doubt the only complete work published on the
+    Westinghouse E-T Locomotive Brake Equipment. Written by an
+    Air-Brake Instructor who knows just what is needed. It covers
+    the subject thoroughly. Everything about the New Westinghouse
+    Engine and Tender Brake Equipment, including the standard No. 5
+    and the Perfected No. 6 style of brake, is treated in detail.
+    Written in plain English and profusely illustrated with Colored
+    Plates, which enable one to trace the flow of pressures
+    throughout the entire equipment. The best book ever published on
+    the Air Brake. Equally good for the beginner and the advanced
+    engineer. Will pass any one through any examination. It informs
+    and enlightens you on every point. Indispensable to every
+    engineman and trainman.
+
+    Contains examination questions and answers on the E-T equipment.
+    Covering what the E-T Brake is. How it should be operated. What
+    to do when defective. Not a question can be asked of the
+    engineman up for promotion, on either the No. 5 or the No. 6 E-T
+    equipment, that is not asked and answered in the book. If you
+    want to thoroughly understand the E-T equipment get a copy of
+    this book. It covers every detail. Makes Air-Brake troubles and
+    examinations easy. Price =$1.50=
+
+
+~MACHINE-SHOP PRACTICE~
+
+
+=American Tool Making and Interchangeable Manufacturing.= By J. V.
+WOODWORTH.
+
+    A "shoppy" book, containing no theorizing, no problematical or
+    experimental devices. There are no badly proportioned and
+    impossible diagrams, no catalogue cuts, but a valuable
+    collection of drawings and descriptions of devices, the rich
+    fruits of the author's own experience. In its 500-odd pages the
+    one subject only, Tool Making, and whatever relates thereto, is
+    dealt with. The work stands without a rival. It is a complete,
+    practical treatise, on the art of American Tool Making and
+    system of interchangeable manufacturing as carried on to-day in
+    the United States. In it are described and illustrated all of
+    the different types and classes of small tools, fixtures,
+    devices, and special appliances which are in general use in all
+    machine-manufacturing and metal-working establishments where
+    economy, capacity, and interchangeability in the production of
+    machined metal parts are imperative. The science of jig making
+    is exhaustively discussed, and particular attention is paid to
+    drill jigs, boring, profiling and milling fixtures and other
+    devices in which the parts to be machined are located and
+    fastened within the contrivances. All of the tools, fixtures,
+    and devices illustrated and described have been or are used for
+    the actual production of work, such as parts of drill presses,
+    lathes, patented machinery, typewriters, electrical apparatus,
+    mechanical appliances, brass goods, composition parts, mould
+    products, sheet-metal articles, drop-forgings, jewelry, watches,
+    medals, coins, etc. 531 pages. Price =$4.00=
+
+
+=HENLEY'S ENCYCLOPEDIA OF PRACTICAL ENGINEERING AND ALLIED TRADES.=
+EDITED by JOSEPH G. HORNER, A.M.I., M.E.
+
+    This set of five volumes contains about 2,500 pages with
+    thousands of illustrations, including diagrammatic and sectional
+    drawings with full explanatory details. This work covers the
+    entire practice of Civil and Mechanical Engineering. The best
+    known experts in all branches of engineering have contributed to
+    these volumes. The Cyclopedia is admirably well adapted to the
+    needs of the beginner and the self-taught practical man, as well
+    as the mechanical engineer, designer, draftsman, shop
+    superintendent, foreman, and machinist. The work will be found a
+    means of advancement to any progressive man. It is encyclopedic
+    in scope, thorough and practical in its treatment on technical
+    subjects, simple and clear in its descriptive matter, and
+    without unnecessary technicalities or formulæ. The articles are
+    as brief as may be and yet give a reasonably clear and explicit
+    statement of the subject, and are written by men who have had
+    ample practical experience in the matters of which they write.
+    It tells you all you want to know about engineering and tells it
+    so simply, so clearly, so concisely, that one cannot help but
+    understand. As a work of reference it is without a peer.
+    Complete set of five volumes, price =$25.00=
+
+
+=The Modern Machinist.= By JOHN T. USHER.
+
+    This is a book, showing by plain description and by profuse
+    engravings made expressly for the work, all that is best, most
+    advanced, and of the highest efficiency in modern machine-shop
+    practice, tools and implements, showing the way by which and
+    through which, as Mr. Maxim says "American machinists have
+    become and are the finest mechanics in the world." Indicating as
+    it does, in every line, the familiarity of the author with every
+    detail of daily experience in the shop, it cannot fail to be of
+    service to any man practically connected with the shaping or
+    finishing of metals.
+
+    There is nothing experimental or visionary about the book, all
+    devices being in actual use and giving good results. It might be
+    called a compendium of shop methods, showing a variety of
+    special tools and appliances which will give new ideas to many
+    mechanics, from the superintendent down to the man at the bench.
+    It will be found a valuable addition to any machinist's library,
+    and should be consulted whenever a new or difficult job is to be
+    done, whether it is boring, milling, turning, or planing, as
+    they are all treated m a practical manner. Fifth edition. 320
+    pages. 250 illustrations. Price =$2.50=
+
+
+=THE WHOLE FIELD OF MECHANICAL MOVEMENTS COVERED BY MR. HISCOX'S TWO
+BOOKS=
+
+    _We publish two books by Gardner D. Hiscox that will keep you
+    from "inventing" things that have been done before, and suggest
+    ways of doing things that you have not thought of before. Many a
+    man spends time and money pondering over some mechanical
+    problem, only to learn, after he has solved the problem, that
+    the same thing has been accomplished and put in practice by
+    others long before. Time and money spent in an effort to
+    accomplish what has already been accomplished are time and money
+    LOST. The whole field of mechanics, every known mechanical
+    movement, and practically every device are covered by these two
+    books. If the thing you want has been invented, it is
+    illustrated in them. If it hasn't been invented, then you'll
+    find in them the nearest things to what you want, some movements
+    or devices that will apply in your case, perhaps; or which will
+    give you a key from which to work. No book or set of books ever
+    published is of more real value to the Inventor, Draftsman, or
+    practical Mechanic than the two volumes described below._
+
+
+=Mechanical Movements, Powers, and Devices.= By GARDNER D. HISCOX.
+
+    This is a collection of 1,890 engravings of different mechanical
+    motions and appliances, accompanied by appropriate text, making
+    it a book of great value to the inventor, the draftsman, and to
+    all readers with mechanical tastes. The book is divided into
+    eighteen sections or chapters, in which the subject-matter is
+    classified under the following heads: Mechanical Powers;
+    Transmission of Power; Measurement of Power; Steam Power; Air
+    Power Appliances; Electric Power and Construction; Navigation
+    and Roads; Gearing; Motion and Devices; Controlling Motion;
+    Horological; Mining; Mill and Factory Appliances; Construction
+    and Devices; Drafting Devices; Miscellaneous Devices, etc. 15th
+    Edition. 400 octavo pages. Price =$3.00=
+
+
+=Mechanical Appliances, Mechanical Movements and Novelties of
+Construction.= By GARDNER D. HISCOX.
+
+    This is a supplementary volume to the one upon mechanical
+    movements. Unlike the first volume, which is more elementary in
+    character, this volume contains illustrations and descriptions
+    of many combinations of motions and of mechanical devices and
+    appliances found in different lines of machinery, each device
+    being shown by a line drawing with a description showing its
+    working parts and the method of operation. From the multitude of
+    devices described and illustrated might be mentioned, in
+    passing, such items as conveyors and elevators, Pony brakes,
+    thermometers, various types of boilers, solar engines, oil-fuel
+    burners, condensers, evaporators, Corliss and other valve gears,
+    governors, gas engines, water motors of various descriptions,
+    air ships, motors and dynamos, automobile and motor bicycles,
+    railway lock signals, car couplers, link and gear motions, ball
+    bearings, breech-block mechanism for heavy guns, and a large
+    accumulation of others of equal importance. One thousand
+    specially made engravings. 396 octavo pages. Fourth edition.
+    Price =$3.00=
+
+
+=Machine-Shop Tools and Shop Practice.= By W. H. VANDERVOORT.
+
+    A work of 555 pages and 673 illustrations, describing in every
+    detail the construction, operation and manipulation of both hand
+    and machine tools. Includes chapters on filing, fitting and
+    scraping surfaces; on drills, reamers, taps and dies; the lathe
+    and its tools: planers, shapers, and their tools; milling
+    machines and cutters; gear cutters and gear cutting; drilling
+    machines and drill work; grinding machines and their work;
+    hardening and tempering; gearing, belting and transmission
+    machinery; useful data and tables. Sixth edition. Price =$3.00=
+
+
+=Machine-Shop Arithmetic.= By COLVIN-CHENEY.
+
+    This is an arithmetic of the things you have to do with daily.
+    It tells you plainly about: how to find areas in figures; how to
+    find surface or volume of balls or spheres; handy ways for
+    calculating; about compound gearing; cutting screw threads on
+    any lathe; drilling for taps; speeds of drills; taps, emery
+    wheels, grindstones, milling cutters, etc.; all about the Metric
+    system with conversion tables; properties of metals; strength of
+    bolts and nuts; decimal equivalent of an inch. All sorts of
+    machine-shop figuring and 1,001 other things, any one of which
+    ought to be worth more than the price of this book to you, as it
+    saves you the trouble of bothering the boss. 6th Edition. 131
+    pages. Price =50 cents=
+
+
+=Modern Machine-Shop Construction, Equipment and Management.= By OSCAR
+E. PERRIGO.
+
+    The only work published that describes the Modern Shop or
+    Manufacturing Plant from the time the grass is growing on the
+    site intended for it until the finished product is shipped. Just
+    the book needed by those contemplating the erection of modern
+    shop buildings, the rebuilding and reorganization of old ones,
+    or the introduction of Modern Shop Methods, time and cost
+    systems. It is a book written and illustrated by a practical
+    shop man for practical shop men who are too busy to read
+    theories and want facts. It is the most complete all-round book
+    of its kind ever published. Second Edition, Revised. 384 large
+    quarto pages. 219 original and specially made illustrations. 2nd
+    Revised and Enlarged Edition. Price =$5.00=
+
+
+=Modern Milling Machines: Their Design, Construction, and Operation.= By
+JOSEPH G. HORNER.
+
+    This book describes and illustrates the Milling Machine and its
+    work in such a plain, clear and forceful manner, and illustrates
+    the subject so clearly and completely, that the up-to-date
+    machinist, student or mechanical engineer cannot afford to do
+    without the valuable information which it contains. It describes
+    not only the early machines of this class, but notes their
+    gradual development into the splendid machines of the present
+    day, giving the design and construction of the various types,
+    forms, and special features produced by prominent manufacturers,
+    American and foreign. 304 pages, 300 illustrations. Cloth. Price
+    =$4.00=
+
+
+="Shop Kinks."= By ROBERT GRIMSHAW.
+
+    A book of 400 pages and 222 illustrations, being entirely
+    different from any other book on machine-shop practice.
+    Departing from conventional style, the author avoids universal
+    or common shop usage and limits his work to showing special ways
+    of doing things better, more cheaply and more rapidly than
+    usual. As a result the advanced methods of representative
+    establishments of the world are placed at the disposal of the
+    reader. This book shows the proprietor where large savings are
+    possible, and how products may be improved. To the employee it
+    holds out suggestions that, properly applied, will hasten his
+    advancement. No shop can afford to be without it. It bristles
+    with valuable wrinkles and helpful suggestions. It will benefit
+    all, from apprentice to proprietor. Every machinist, at any age,
+    should study its pages. Fifth edition. Price =$2.50=
+
+
+=Threads and Thread Cutting.= By COLVIN and STABEL.
+
+    This clears up many of the mysteries of thread-cutting, such as
+    double and triple threads, internal threads, catching threads,
+    use of hobs, etc. Contains a lot of useful hints and several
+    tables. Third edition. Price =25 cents=
+
+
+~MANUAL TRAINING~
+
+
+=Economics of Manual Training.= By LOUIS ROUILLION.
+
+    The only book published that gives just the information needed
+    by all interested in Manual Training, regarding Buildings,
+    Equipment, and Supplies. Shows exactly what is needed for all
+    grades of the work from the Kindergarten to the High and Normal
+    School. Gives itemized lists of everything used in Manual
+    Training Work and tells just what it ought to cost. Also shows
+    where to buy supplies, etc. Contains 174 pages, and is fully
+    illustrated. Second edition. Price =$1.50=
+
+
+~MARINE ENGINEERING~
+
+
+=The Naval Architect's and Shipbuilder's Pocket Book of Formulæ, Rules,
+and Tables and Marine Engineer's and Surveyor's Handy Book of
+Reference.= By CLEMENT MACKROW and LLOYD WOOLLARD.
+
+    The eleventh Revised and Enlarged Edition of this most
+    comprehensive work has just been issued. It is absolutely
+    indispensable to all engaged in the Shipbuilding Industry, as it
+    condenses into a compact form all data and formulæ that are
+    ordinarily required. The book is completely up to date,
+    including among other subjects a section on Aeronautics. 750
+    pages, limp leather binding. Price =$5.00 net=
+
+
+=Marine Engines and Boilers: Their Design and Construction.= By DR. G.
+BAUER, LESLIE S. ROBERTSON and S. BRYAN DONKIN.
+
+    In the words of Dr. Bauer, the present work owes its origin to
+    an oft felt want of a condensed treatise embodying the
+    theoretical and practical rules used in designing marine engines
+    and boilers. The need of such a work has been felt by most
+    engineers engaged in the construction and working of marine
+    engines, not only by the younger men, but also by those of
+    greater experience. The fact that the original German work was
+    written by the chief engineer of the famous Vulcan Works,
+    Stettin, is in itself a guarantee that this book is in all
+    respects thoroughly up-to-date, and that it embodies all the
+    information which is necessary for the design and construction
+    of the highest types of marine engines and boilers. It may be
+    said that the motive power which Dr. Bauer has placed in the
+    fast German liners that have been turned out of late years from
+    the Stettin Works represent the very best practice in marine
+    engineering of the present day. The work is clearly written,
+    thoroughly systematic, theoretically sound; while the character
+    of the plans, drawings, tables, and statistics is without
+    reproach. The illustrations are careful reproductions from
+    actual working drawings, with some well-executed photographic
+    views of completed engines and boilers. 744 pages, 550
+    illustrations and numerous tables. Cloth. Price =$9.00 net=
+
+
+~MINING~
+
+
+=Ore Deposits, with a Chapter on Hints to Prospectors.= By J. P.
+JOHNSON.
+
+    This book gives a condensed account of the ore deposits at
+    present known in South Africa. It is also intended as a guide to
+    the prospector. Only an elementary knowledge of geology and some
+    mining experience are necessary in order to understand this
+    work. With these qualifications, it will materially assist one
+    in his search for metalliferous mineral occurrences and, so far
+    as simple ores are concerned, should enable one to form some
+    idea of the possibilities of any he may find. Illustrated.
+    Cloth. Price =$2.00=
+
+
+=Practical Coal Mining.= By T. H. COCKIN.
+
+    An important work, containing 428 pages and 213 illustrations,
+    complete with practical details, which will intuitively impart
+    to the reader not only a general knowledge of the principles of
+    coal mining, but also considerable insight into allied subjects.
+    The treatise is positively up-to-date in every instance, and
+    should be in the hands of every colliery engineer, geologist,
+    mine operator, superintendent, foreman, and all others who are
+    interested in or connected with the industry. 3d Edition. Cloth.
+    Price =$2.50=
+
+
+=Physics and Chemistry of Mining.= By T. H. BYROM.
+
+    A practical work for the use of all preparing for examinations
+    in mining or qualifying for colliery managers' certificates. The
+    aim of the author in this excellent book is to place clearly
+    before the reader useful and authoritative data which will
+    render him valuable assistance in his studies. The only work of
+    its kind published. The information incorporated in it will
+    prove of the greatest practical utility to students, mining
+    engineers, colliery managers, and all others who are specially
+    interested in the present-day treatment of mining problems. 160
+    pages, illustrated. Price =$2.00=
+
+
+~PATTERN MAKING~
+
+
+=Practical Pattern Making.= By F. W. BARROWS.
+
+    This book, now in its second edition, is a comprehensive and
+    entirely practical treatise on the subject of pattern making,
+    illustrating pattern work in both wood and metal, and with
+    definite instructions on the use of plaster of paris in the
+    trade. It gives specific and detailed descriptions of the
+    materials used by pattern makers, and describes the tools, both
+    those for the bench and the more interesting machine tools,
+    having complete chapters on the Lathe, the Circular Saw, and the
+    Band Saw. It gives many examples of pattern work, each one fully
+    illustrated and explained with much detail. These examples, in
+    their great variety, offer much that will be found of interest
+    to all pattern makers, and especially to the younger ones, who
+    are seeking information on the more advanced branches of their
+    trade.
+
+    In this second edition of the work will be found much that is
+    new, even to those who have long practised this exacting trade.
+    In the description of patterns as adapted to the Moulding
+    Machine many difficulties which have long prevented the rapid
+    and economical production of castings are overcome; and this
+    great, new branch of the trade is given much space. Stripping
+    plate and stool plate work and the less expensive vibrator, or
+    rapping plate work, are all explained in detail.
+
+    Plain, every-day rules for lessening the cost of patterns, with
+    a complete system of cost keeping, a detailed method of marking,
+    applicable to all branches of the trade, with complete
+    information showing what the pattern is, its specific title, its
+    cost, date of production, material of which it is made, the
+    number of pieces and core-boxes, and its location in the pattern
+    safe, all condensed into a most complete card record, with cross
+    index. The book closes with an original and practical method for
+    the inventory and valuation of patterns. Containing nearly 350
+    pages and 170 illustrations. Price =$2.00=
+
+
+~PERFUMERY~
+
+
+=Perfumes and Cosmetics: Their Preparation and Manufacture.= By G. W.
+ASKINSON, Perfumer.
+
+    A comprehensive treatise, in which there has been nothing
+    omitted that could be of value to the perfumer or manufacturer
+    of toilet preparations. Complete directions for making
+    handkerchief perfumes, smelling-salts, sachets, fumigating
+    pastilles; preparations for the care of the skin, the mouth, the
+    hair, cosmetics, hair dyes and other toilet articles are given,
+    also a detailed description of aromatic substances; their
+    nature, tests of purity, and wholesome manufacture, including a
+    chapter on synthetic products, with formulas for their use. A
+    book of general as well as professional interest, meeting the
+    wants not only of the druggist and perfume manufacturer, but
+    also of the general public. Among the contents are: 1. The
+    History of Perfumery. 2. About Aromatic Substances in General.
+    3. Odors from the Vegetable Kingdom. 4. The Aromatic Vegetable
+    Substances Employed in Perfumery. 5. The Animal Substances Used
+    in Perfumery. 6. The Chemical Products Used in Perfumery. 7. The
+    Extraction of Odors. 8. The Special Characteristics of Aromatic
+    Substances. 9 The Adulteration of Essential Oils and Their
+    Recognition. 10. Synthetic Products. 11. Table of Physical
+    Properties of Aromatic Chemicals. 12. The Essences or Extracts
+    Employed in Perfumery. 13. Directions for Making the Most
+    Important Essences and Extracts. 14. The Division of Perfumery.
+    15. The Manufacture of Handkerchief Perfumes. 16. Formulas for
+    Handkerchief Perfumes. 17. Ammoniacal and Acid Perfumes. 18. Dry
+    Perfumes. 19. Formulas for Dry Perfumes. 20. The Perfumes Used
+    for Fumigation. 21. Antiseptic and Therapeutic Value of
+    Perfumes. 22. Classification of Odors. 23. Some Special
+    Perfumery Products. 24. Hygiene and Cosmetic Perfumery. 25.
+    Preparations for the Care of the Skin. 26. Manufacture of
+    Casein. 27. Formulas for Emulsions. 28. Formulas for Cream. 29.
+    Formulas for Meals, Pastes and Vegetable Milk. 30. Preparations
+    Used for the Hair. 31. Formulas for Hair Tonics and Restorers.
+    32. Pomades and Hair Oils 33. Formulas for the Manufacture of
+    Pomades and Hair Oils. 34. Hair Dyes and Depilatories. 35. Wax
+    Pomades, Bandolines and Brilliantines. 36. Skin Cosmetics and
+    Face Lotions. 37. Preparations for the Nails. 38. Water
+    Softeners and Bath Salts. 39. Preparations for the Care of the
+    Mouth. 40. The Colors Used in Perfumery. 41. The Utensils Used
+    in the Toilet. Fourth edition, much enlarged and brought up to
+    date. Nearly 400 pages, illustrated. Price =$5.00=
+
+    WHAT IS SAID OF THIS BOOK:
+
+    "The most satisfactory work on the subject of Perfumery that we
+    have ever seen."
+
+    "We feel safe in saying that here is a book on Perfumery that
+    will not disappoint you, for it has practical and excellent
+    formulæ that are within your ability to prepare readily."
+
+    "We recommend the volume as worthy of confidence, and say that
+    no purchaser will be disappointed in securing from its pages
+    good value for its cost, and a large dividend on the same, even
+    if he should use but one per cent. of its working formulæ. There
+    is money in it for every user of its
+    information."--_Pharmaceutical Record._
+
+
+~PLUMBING~
+
+
+=Mechanical Drawing for Plumbers.= By R. M. STARBUCK.
+
+    A concise, comprehensive and practical treatise on the subject
+    of mechanical drawing in its various modern applications to the
+    work of all who are in any way connected with the plumbing
+    trade. Nothing will so help the plumber in estimating and in
+    explaining work to customers and workmen as a knowledge of
+    drawing, and to the workman it is of inestimable value if he is
+    to rise above his position to positions of greater
+    responsibility. Among the chapters contained are: 1. Value to
+    plumber of knowledge of drawing; tools required and their use;
+    common views needed in mechanical drawing. 2. Perspective versus
+    mechanical drawing in showing plumbing construction. 3. Correct
+    and incorrect methods in plumbing drawing; plan and elevation
+    explained. 4. Floor and cellar plans and elevation; scale
+    drawings; use of triangles. 5. Use of triangles; drawing of
+    fittings, traps, etc. 6. Drawing plumbing elevations and
+    fittings. 7. Instructions in drawing plumbing elevations. 8. The
+    drawing of plumbing fixtures; scale drawings. 9. Drawings of
+    fixtures and fittings. 10. Inking of drawings. 11. Shading of
+    drawings. 12. Shading of drawings. 13. Sectional drawings;
+    drawing of threads. 14. Plumbing elevations from architect's
+    plan. 15. Elevations of separate parts of the plumbing system.
+    16. Elevations from the architect's plans. 17. Drawings of
+    detail plumbing connections. 18. Architect's plans and plumbing
+    elevations of residence. 19. Plumbing elevations of residence
+    (_continued_); plumbing plans for cottage. 20. Plumbing
+    elevations; roof connections. 21. Plans and plumbing elevations
+    for six-flat building. 22. Drawing of various parts of the
+    plumbing system; use of scales. 23. Use of architect's scales.
+    24. Special features in the illustrations of country plumbing.
+    25. Drawing of wrought-iron piping, valves, radiators, coils,
+    etc. 26. Drawing of piping to illustrate heating systems. 150
+    illustrations. Price =$1.50=
+
+
+=Modern Plumbing Illustrated.= By R. M. STARBUCK.
+
+    This book represents the highest standard of plumbing work. It
+    has been adopted and used as a reference book by the United
+    States Government in its sanitary work in Cuba, Porto Rico and
+    the Philippines, and by the principal Boards of Health of the
+    United States and Canada.
+
+    It gives connections, sizes and working data for all fixtures
+    and groups of fixtures. It is helpful to the master plumber in
+    demonstrating to his customers and in figuring work. It gives
+    the mechanic and student quick and easy access to the best
+    modern plumbing practice. Suggestions for estimating plumbing
+    construction are contained in its pages. This book represents,
+    in a word, the latest and best up-to-date practice and should be
+    in the hands of every architect, sanitary engineer and plumber
+    who wishes to keep himself up to the minute on this important
+    feature of construction. Contains following chapters, each
+    illustrated with a full-page plate: Kitchen sink, laundry tubs,
+    vegetable wash sink; lavatories, pantry sinks, contents of
+    marble slabs; bath tub, foot and sitz bath, shower bath; water
+    closets, venting of water closets; low-down water closets, water
+    closets operated by flush valves, water closet range; slop sink,
+    urinals, the bidet; hotel and restaurant sink, grease trap;
+    refrigerators, safe wastes, laundry waste, lines of
+    refrigerators, bar sinks, soda fountain sinks; horse stall,
+    frost-proof water closets; connections for S traps, venting;
+    connections for drum traps; soil-pipe connections; supporting of
+    soil pipe; main trap and fresh-air inlet: floor drains and
+    cellar drains, subsoil drainage; water closets and floor
+    connections; local venting; connections for bath rooms;
+    connections for bath rooms, _continued_; examples of poor
+    practice; roughing work ready for test; testing of plumbing
+    systems; method of continuous venting; continuous venting for
+    two-floor work; continuous venting for two lines of fixtures on
+    three or more floors; continuous venting of water closets;
+    plumbing for cottage house; construction for cellar piping;
+    plumbing for residence, use of special fittings; plumbing for
+    two-flat house: plumbing for apartment building, plumbing for
+    double apartment building; plumbing for office building;
+    plumbing for public toilet rooms; plumbing for public toilet
+    rooms, _continued_; plumbing for bath establishment; plumbing
+    for engine house, factory plumbing, automatic flushing for
+    schools, factories, etc.; use of flushing valves; urinals for
+    public toilet rooms; the Durham system, the destruction of pipes
+    by electrolysis; construction of work without use of lead;
+    automatic sewage lift; automatic sump tank; country plumbing;
+    construction of cesspools; septic tank and automatic sewage
+    siphon; water supply for country house; thawing of water mains
+    and service by electricity; double boilers; hot water supply of
+    large buildings; automatic control of hot-water tank;
+    suggestions for estimating plumbing construction. 407 octavo
+    pages, fully illustrated by 57 full-page engravings. Third,
+    revised and enlarged edition, just issued. Price =$4.00=
+
+
+=Standard Practical Plumbing.= By R. M. STARBUCK.
+
+    A complete practical treatise of 450 pages, covering the subject
+    of Modern Plumbing in all its branches, a large amount of space
+    being devoted to a very complete and practical treatment of the
+    subject of Hot Water Supply and Circulation and Range Boiler
+    Work. Its thirty chapters include about every phase of the
+    subject one can think of, making it an indispensable work to the
+    master plumber, the journeyman plumber, and the apprentice
+    plumber, containing chapters on: the plumber's tools; wiping
+    solder; composition and use; joint wiping; lead work; traps;
+    siphonage of traps; venting; continuous venting; house sewer and
+    sewer connections; house drain; soil piping, roughing; main trap
+    and fresh air inlet; floor, yard, cellar drains, rain leaders,
+    etc.; fixture wastes; water closets; ventilation; improved
+    plumbing connections; residence plumbing; plumbing for hotels,
+    schools, factories, stables, etc.; modern country plumbing;
+    filtration of sewage and water supply; hot and cold supply;
+    range boilers; circulation; circulating pipes; range boiler
+    problems; hot water for large buildings; water lift and its use;
+    multiple connections for hot water boilers; heating of radiation
+    by supply system; theory for the plumber; drawing for the
+    plumber. Fully illustrated by 347 engravings. Price =$3.00=
+
+
+~RECIPE BOOK~
+
+
+=Henley's Twentieth Century Book of Recipes, Formulas and Processes.=
+Edited by GARDNER D. HISCOX.
+
+    The most valuable Techno-chemical Formula Book published,
+    including over 10,000 selected scientific, chemical,
+    technological, and practical recipes and processes.
+
+    This is the most complete Book of Formulas ever published,
+    giving thousands of recipes for the manufacture of valuable
+    articles for everyday use. Hints, Helps, Practical Ideas, and
+    Secret Processes are revealed within its pages. It covers every
+    branch of the useful arts and tells thousands of ways of making
+    money, and is just the book everyone should have at his command.
+
+    Modern in its treatment of every subject that properly falls
+    within its scope, the book may truthfully be said to present the
+    very latest formulas to be found in the arts and industries, and
+    to retain those processes which long experience has proven
+    worthy of a permanent record. To present here even a limited
+    number of the subjects which find a place in this valuable work
+    would be difficult. Suffice to say that in its pages will be
+    found matter of intense interest and immeasurably practical
+    value to the scientific amateur and to him who wishes to obtain
+    a knowledge of the many processes used in the arts, trades and
+    manufacture, a knowledge which will render his pursuits more
+    instructive and remunerative. Serving as a reference book to the
+    small and large manufacturer and supplying intelligent seekers
+    with the information necessary to conduct a process, the work
+    will be found of inestimable worth to the Metallurgist, the
+    Photographer, the Perfumer, the Painter, the Manufacturer of
+    Glues, Pastes, Cements, and Mucilages, the Compounder of Alloys,
+    the Cook, the Physician, the Druggist, the Electrician, the
+    Brewer, the Engineer, the Foundryman, the Machinist, the Potter,
+    the Tanner, the Confectioner, the Chiropodist, the Manicurist,
+    the Manufacturer of Chemical Novelties and Toilet Preparations,
+    the Dyer, the Electroplater, the Enameler, the Hat Maker, the
+    Ink Manufacturer, the Optician, the Farmer, the Dairyman, the
+    Paper Maker, the Wood and Metal Worker, the Chandler and Soap
+    Maker, the Veterinary Surgeon, and the Technologist in general.
+
+    A mine of information, and up-to-date in every respect. A book
+    which will prove of value to EVERYONE, as it covers every branch
+    of the Useful Arts. Every home needs this book; every office,
+    every factory, every store, every public and private
+    enterprise--EVERYWHERE--should have a copy. 800 pages. Price
+    =$3.00=
+
+    WHAT IS SAID OF THIS BOOK:
+
+    "Your Twentieth Century Book of Recipes, Formulas, and Processes
+    duly received. I am glad to have a copy of it, and if I could
+    not replace it, money couldn't buy it. It is the best thing of
+    the sort I ever saw." (Signed) M. E. TRUX, Sparta, Wis.
+
+    "There are few persons who would not be able to find in the book
+    some single formula that would repay several times the cost of
+    the book."--_Merchants' Record and Show Window._
+
+    "I purchased your book, 'Henley's Twentieth Century Book of
+    Recipes, Formulas and Processes,' about a year ago and it is
+    worth its weight in _gold_."--WM. H. MURRAY, Bennington, Vt.
+
+    "ONE OF THE WORLD'S MOST USEFUL BOOKS"
+
+    "Some time ago I got one of your 'Twentieth Century Books of
+    Formulas,' and have made my living from it ever since. I am
+    alone since my husband's death with two small children to care
+    for and am trying so hard to support them. I have customers who
+    take from me Toilet Articles I put up, following directions
+    given in the book, and I have found everyone of them to be
+    fine."--MRS. J. H. MCMAKEN, West Toledo, Ohio.
+
+
+~RUBBER~
+
+
+=Rubber Hand Stamps and the Manipulation of India Rubber.= BY T. O'CONOR
+SLOANE.
+
+    This book gives full details on all points, treating in a
+    concise and simple manner the elements of nearly everything it
+    is necessary to understand for a commencement in any branch of
+    the India Rubber Manufacture. The making of all kinds of Rubber
+    Hand Stamps, Small Articles of India Rubber, U. S. Government
+    Composition, Dating Hand Stamps, the Manipulation of Sheet
+    Rubber, Toy Balloons, India Rubber Solutions, Cements,
+    Blackings, Renovating, Varnish, and Treatment for India Rubber
+    Shoes, etc.; the Hektograph Stamp Inks, and Miscellaneous Notes,
+    with a Short Account of the Discovery, Collection and
+    Manufacture of India Rubber, are set forth in a manner designed
+    to be readily understood, the explanations being plain and
+    simple. Including a chapter on Rubber Tire Making and
+    Vulcanizing; also a chapter on the uses of rubber in Surgery and
+    Dentistry. 3rd Revised and Enlarged Edition. 175 pages.
+    Illustrated =$1.00=
+
+
+~SAWS~
+
+
+=Saw Filing and Management of Saws.= By ROBERT GRIMSHAW.
+
+    A practical hand-book on filing, gumming, swaging, hammering,
+    and the brazing of band saws, the speed, work, and power to run
+    circular saws, etc. A handy book for those who have charge of
+    saws, or for those mechanics who do their own filing, as it
+    deals with the proper shape and pitches of saw teeth of all
+    kinds and gives many useful hints and rules for gumming,
+    setting, and filing, and is a practical aid to those who use
+    saws for any purpose. Complete tables of proper shape, pitch,
+    and saw teeth as well as sizes and number of teeth of various
+    saws are included. 3rd Edition, Revised and Enlarged.
+    Illustrated. Price =$1.00=
+
+
+~STEAM ENGINEERING~
+
+
+=American Stationary Engineering.= By W. E. CRANE.
+
+    This book begins at the boiler room and takes in the whole power
+    plant. A plain talk on every-day work about engines, boilers,
+    and their accessories. It is not intended to be scientific or
+    mathematical. All formulas are in simple form so that any one
+    understanding plain arithmetic can readily understand any of
+    them. The author has made this the most practical book in print;
+    has given the results of his years of experience, and has
+    included about all that has to do with an engine room or a power
+    plant. You are not left to guess at a single point. You are
+    shown clearly what to expect under the various conditions; how
+    to secure the best results; ways of preventing "shut downs" and
+    repairs; in short, all that goes to make up the requirements of
+    a good engineer, capable of taking charge of a plant. It's plain
+    enough for practical men and yet of value to those high in the
+    profession.
+
+    A partial list of contents is: The boiler room, cleaning
+    boilers, firing, feeding; pumps, inspection and repair;
+    chimneys, sizes and cost; piping; mason work; foundations;
+    testing cement; pile driving; engines, slow and high speed;
+    valves; valve setting; Corliss engines, setting valves, single
+    and double eccentric; air pumps and condensers; different types
+    of condensers; water needed; lining up; pounds; pins not square
+    in crosshead or crank; engineers' tools; pistons and piston
+    rings; bearing metal; hardened copper; drip pipes from cylinder
+    jacket; belts, how made, care of; oils; greases; testing
+    lubricants; rules and tables, including steam tables; areas of
+    segments; squares and square roots; cubes and cube root; areas
+    and circumferences of circles. Notes on: Brick work; explosions;
+    pumps; pump valves; heaters, economizers; safety valves; lap,
+    lead, and clearance. Has a complete examination for a license,
+    etc., etc. 3rd Edition. 345 pages, illustrated. Price =$2.00=
+
+
+=Engine Runner's Catechism.= By ROBERT GRIMSHAW.
+
+    A practical treatise for the stationary engineer, telling how to
+    erect, adjust, and run the principal steam engines in use in the
+    United States. Describing the principal features of various
+    special and well-known makes of engines: Temper Cut-off,
+    Shipping and Receiving Foundations, Erecting and Starting, Valve
+    Setting, Care and Use, Emergencies, Erecting and Adjusting
+    Special Engines.
+
+    The questions asked throughout the catechism are plain and to
+    the point, and the answers are given in such simple language as
+    to be readily understood by anyone. All the instructions given
+    are complete and up-to-date; and they are written in a popular
+    style, without any technicalities or mathematical formulæ. The
+    work is of a handy size for the pocket, clearly and well
+    printed, nicely bound, and profusely illustrated.
+
+    To young engineers this catechism will be of great value,
+    especially to those who may be preparing to go forward to be
+    examined for certificates of competency; and to engineers
+    generally it will be of no little service, as they will find in
+    this volume more really practical and useful information than is
+    to be found anywhere else within a like compass. 387 pages. 7th
+    Edition. Price =$2.00=
+
+
+=Modern Steam Engineering in Theory and Practice.= By GARDNER D. HISCOX.
+
+    This is a complete and practical work issued for Stationary
+    Engineers and Firemen, dealing with the care and management of
+    boilers, engines, pumps, superheated steam, refrigerating
+    machinery, dynamos, motors, elevators, air compressors, and all
+    other branches with which the modern engineer must be familiar.
+    Nearly 200 questions with their answers on steam and electrical
+    engineering, likely to be asked by the Examining Board, are
+    included.
+
+    Among the chapters are: Historical: steam and its properties;
+    appliances for the generation of steam; types of boilers;
+    chimney and its work; heat economy of the feed water; steam
+    pumps and their work; incrustation and its work; steam above
+    atmospheric pressure; flow of steam from nozzles; superheated
+    steam and its work; adiabatic expansion of steam; indicator and
+    its work; steam engine proportions; slide valve engines and
+    valve motion; Corliss engine and its valve gear; compound engine
+    and its theory; triple and multiple expansion engine; steam
+    turbine; refrigeration; elevators and their management; cost of
+    power; steam engine troubles; electric power and electric
+    plants. 487 pages, 405 engravings. 3rd Edition. Price =$3.00=
+
+
+=Steam Engine Catechism.= By ROBERT GRIMSHAW.
+
+    This unique volume of 413 pages is not only a catechism on the
+    question and answer principle but it contains formulas and
+    worked-out answers for all the Steam problems that appertain to
+    operation and management of the Steam Engine. Illustrations of
+    various valves and valve gear with their principles of operation
+    are given. Thirty-four Tables that are indispensable to every
+    engineer and fireman that wishes to be progressive and is
+    ambitious to become master of his calling are within its pages.
+    It is a most valuable instructor in the service of Steam
+    Engineering. Leading engineers have recommended it as a valuable
+    educator for the beginner as well as a reference book for the
+    engineer. It is thoroughly indexed for every detail. Every
+    essential question on the Steam Engine with its answer is
+    contained in this valuable work. 16th Edition. Price =$2.00=
+
+
+=Steam Engineer's Arithmetic.= By COLVIN-CHENEY.
+
+    A practical pocket-book for the steam engineer. Shows how to
+    work the problems of the engine room and shows "why." Tells how
+    to figure horsepower of engines and boilers; area of boilers;
+    has tables of areas and circumferences; steam tables; has a
+    dictionary of engineering terms. Puts you on to all of the
+    little kinks in figuring whatever there is to figure around a
+    power plant. Tells you about the heat unit; absolute zero;
+    adiabatic expansion; duty of engines; factor of safety; and a
+    thousand and one other things; and everything is plain and
+    simple--not the hardest way to figure, but the easiest. 2nd
+    Edition. Price =50 Cents=
+
+
+=Engine Tests and Boiler Efficiencies.= By J. BUCHETTI.
+
+    This work fully describes and illustrates the method of testing
+    the power of steam engines, turbines and explosive motors. The
+    properties of steam and the evaporative power of fuels.
+    Combustion of fuel and chimney draft; with formulas explained or
+    practically computed. 255 pages, 179 illustrations. Price
+    =$3.00=
+
+
+=Horsepower Chart.=
+
+    Shows the horsepower of any stationary engine without
+    calculation. No matter what the cylinder diameter of stroke, the
+    steam pressure of cut-off, the revolutions, or whether
+    condensing or non-condensing, it's all there. Easy to use.
+    accurate, and saves time and calculations. Especially useful to
+    engineers and designers. Price =50 Cents=
+
+
+~STEAM HEATING AND VENTILATION~
+
+
+=Practical Steam, Hot-Water Heating and Ventilation.= By A. G. KING.
+
+    This book is the standard and latest work published on the
+    subject and has been prepared for the use of all engaged in the
+    business of steam, hot-water heating, and ventilation. It is an
+    original and exhaustive work. Tells how to get heating
+    contracts, how to install heating and ventilating apparatus, the
+    best business methods to be used, with "Tricks of the Trade" for
+    shop use. Rules and data for estimating radiation and cost and
+    such tables and information as make it an indispensable work for
+    everyone interested in steam, hot-water heating, and
+    ventilation. It describes all the principal systems of steam,
+    hot-water, vacuum, vapor, and vacuum-vapor heating, together
+    with the new accelerated systems of hot-water circulation,
+    including chapters on up-to-date methods of ventilation and the
+    fan or blower system of heating and ventilation. Containing
+    chapters on: I. Introduction. II. Heat. III. Evolution of
+    artificial heating apparatus. IV. Boiler surface and settings.
+    V. The chimney flue. VI. Pipe and fittings. VII. Valves, various
+    kinds. VIII. Forms of radiating surfaces. IX. Locating of
+    radiating surfaces. X. Estimating radiation. XI. Steam-heating
+    apparatus XII. Exhaust-steam heating. XIII. Hot-water heating.
+    XIV. Pressure systems of hot-water work. XV. Hot-water
+    appliances. XVI. Greenhouse heating. XVII. Vacuum vapor and
+    vacuum exhaust heating. XVIII. Miscellaneous heating. XIX.
+    Radiator and pipe connections. XX. Ventilation. XXI. Mechanical
+    ventilation and hot-blast heating. XXII. Steam appliances.
+    XXIII. District heating. XXIV. Pipe and boiler covering. XXV.
+    Temperature regulation and heat control. XXVI. Business methods.
+    XXVII. Miscellaneous. XXVIII. Rules, tables, and useful
+    information. 367 pages, 300 detailed engravings. 2nd
+    Edition--Revised. Price =$3.00=
+
+
+=Five Hundred Plain Answers to Direct Questions on Steam, Hot-Water,
+Vapor and Vacuum Heating Practice.= By ALFRED G. KING.
+
+    This work, just off the press, is arranged in question and
+    answer form; it is intended as a guide and text-book for the
+    younger, inexperienced fitter and as a reference book for all
+    fitters. This book tells "how" and also tells "why". No work of
+    its kind has ever been published. It answers all the questions
+    regarding each method or system that would be asked by the steam
+    fitter or heating contractor, and may be used as a text or
+    reference book, and for examination questions by Trade Schools
+    or Steam Fitters' Associations. Rules, data, tables and
+    descriptive methods are given, together with much other detailed
+    information of daily practical use to those engaged in or
+    interested in the various methods of heating. Valuable to those
+    preparing for examinations. Answers every question asked
+    relating to modern Steam, Hot-Water, Vapor and Vacuum Heating.
+    Among the contents are: The Theory and Laws of Heat. Methods of
+    Heating. Chimneys and Flues. Boilers for Heating. Boiler
+    Trimmings and Settings. Radiation. Steam Heating. Boiler,
+    Radiator and Pipe Connections for Steam Heating. Hot Water
+    Heating. The Two-Pipe Gravity System of Hot Water Heating. The
+    Circuit System of Hot Water Heating. The Overhead System of Hot
+    Water Heating. Boiler, Radiator and Pipe Connections for Gravity
+    Systems of Hot Water Heating. Accelerated Hot Water Heating.
+    Expansion Tank Connections. Domestic Hot Water Heating. Valves
+    and Air Valves. Vacuum Vapor and Vacuo-Vapor Heating. Mechanical
+    Systems of Vacuum Heating. Non-Mechanical Vacuum Systems. Vapor
+    Systems. Atmospheric and Modulating Systems. Heating
+    Greenhouses. Information, Rules and Tables. 200 pages, 127
+    illustrations. Octavo. Cloth. Price =$1.50=
+
+
+~STEEL~
+
+
+=Steel: Its Selection, Annealing, Hardening, and Tempering.= By E. R.
+MARKHAM.
+
+    This work was formerly known as "The American Steel Worker," but
+    on the publication of the new, revised edition, the publishers
+    deemed it advisable to change its title to a more suitable one.
+    It is the standard work on Hardening, Tempering, and Annealing
+    Steel of all kinds. This book tells how to select, and how to
+    work, temper, harden, and anneal steel for everything on earth.
+    It doesn't tell how to temper one class of tools and then leave
+    the treatment of another kind of tool to your imagination and
+    judgment, but it gives careful instructions for every detail of
+    every tool, whether it be a tap, a reamer or just a
+    screw-driver. It tells about the tempering of small watch
+    springs, the hardening of cutlery, and the annealing of dies. In
+    fact, there isn't a thing that a steel worker would want to know
+    that isn't included. It is the standard book on selecting,
+    hardening and tempering all grades of steel. Among the chapter
+    headings might be mentioned the following subjects:
+    Introduction; the workman; steel; methods of heating; heating
+    tool steel; forging; annealing; hardening baths; baths for
+    hardening; hardening steel; drawing the temper after hardening;
+    examples of hardening; pack hardening; case hardening; spring
+    tempering; making tools of machine steel; special steels; steel
+    for various tools; causes of trouble; high-speed steels, etc.
+    400 pages. Very fully illustrated. Fourth edition. Price =$2.50=
+
+
+=Hardening, Tempering, Annealing, and Forging of Steel.= By J. V.
+WOODWORTH.
+
+    A new work treating in a clear, concise manner all modern
+    processes for the heating, annealing, forging, welding,
+    hardening and tempering of steel, making it a book of great
+    practical value to the metal-working mechanic in general, with
+    special directions for the successful hardening and tempering of
+    all steel tools used in the arts, including milling cutters,
+    taps, thread dies, reamers, both solid and shell, hollow mills,
+    punches and dies, and all kinds of sheet-metal working tools,
+    shear blades, saws, fine cutlery, and metal-cutting tools of all
+    description, as well as for all implements of steel both large
+    and small. In this work the simplest and most satisfactory
+    hardening and tempering processes are given.
+
+    The uses to which the leading brands of steel may be adapted are
+    concisely presented, and their treatment for working under
+    different conditions explained, also the special methods for the
+    hardening and tempering of special brands.
+
+    A chapter devoted to the different processes for case-hardening
+    is also included, and special reference made to the adaptation
+    of machinery steel for tools of various kinds, Fourth edition.
+    288 pages. 201 illustrations. Price =$2.50=
+
+
+~TRACTORS~
+
+
+=The Modern Gas Tractor.= By VICTOR W. PAGÉ, M.E.
+
+    A complete treatise describing all types and sizes of gasoline,
+    kerosene and oil tractors. Considers design and construction
+    exhaustively, gives complete instructions for care, operation
+    and repair, outlines all practical applications on the road and
+    in the field. The best and latest work on farm tractors and
+    tractor power plants. A work needed by farmers, students,
+    blacksmiths, mechanics, salesmen, implement dealers, designers,
+    and engineers. Second edition, revised and enlarged. 504 pages.
+    Nearly 300 illustrations and folding plates. Price =$2.00=
+
+
+~TURBINES~
+
+
+=Marine Steam Turbines.= By DR. G. BAUER and O. LASCHE. Assisted by E.
+LUDWIG and H. VOGEL.
+
+    Translated from the German and edited by M. G. S. Swallow. The
+    book is essentially practical and discusses turbines in which
+    the full expansion of steam passes through a number of separate
+    turbines arranged for driving two or more shafts, as in the
+    Parsons system, and turbines in which the complete expansion of
+    steam from inlet to exhaust pressure occurs in a turbine on one
+    shaft, as in the case of the Curtis machines. It will enable a
+    designer to carry out all the ordinary calculation necessary for
+    the construction of steam turbines, hence it fills a want which
+    is hardly met by larger and more theoretical works. Numerous
+    tables, curves and diagrams will be found, which explain with
+    remarkable lucidity the reason why turbine blades are designed
+    as they are, the course which steam takes through turbines of
+    various types, the thermodynamics of steam turbine calculation,
+    the influence of vacuum on steam consumption of steam turbines,
+    etc. In a word, the very information which a designer and
+    builder of steam turbines most requires. Large octavo, 214
+    pages. Fully illustrated and containing eighteen tables,
+    including an entropy chart. Price, net =$3.50=
+
+
+~WATCH MAKING~
+
+
+=Watchmaker's Handbook.= By CLAUDIUS SAUNIER.
+
+    No work issued can compare with this book for clearness and
+    completeness. It contains 498 pages and is intended as a
+    workshop companion for those engaged in watch-making and allied
+    mechanical arts. Nearly 250 engravings and fourteen plates are
+    included. This is the standard work on watch-making. Price
+    =$3.00=
+
+
+~WELDING~
+
+
+=Automobile Welding with the Oxy-Acetylene Flame.= By M. KEITH DUNHAM.
+
+    Explains in a simple manner apparatus to be used, its care, and
+    how to construct necessary shop equipment. Proceeds then to the
+    actual welding of all automobile parts, in a manner
+    understandable by every one. _Gives principles never to be
+    forgotten._ Aluminum, cast iron, steel, copper, brass, bronze,
+    and malleable iron are fully treated, as well as a clear
+    explanation of the proper manner to burn the carbon out of the
+    combustion head. This book is of utmost value, since the
+    perplexing problems arising when metal is heated to a melting
+    point are fully explained and the proper methods to overcome
+    them shown. 167 pages, fully illustrated. Price =$1.00=
+
+
+
+
+    Every Practical Man Needs A Magazine Which Will Tell Him How To
+    Make And Do Things
+
+
+    _=Have us enter your subscription to the best mechanical magazine
+    on the market. Only one dollar a year for twelve numbers.
+    Subscribe today to=_
+
+    =Everyday Engineering=
+
+A monthly magazine devoted to practical mechanics for everyday men. Its
+aim is to popularize engineering as a science, teaching the elements of
+applied mechanics and electricity in a straightforward and
+understandable manner. The magazine maintains its own experimental
+laboratory where the devices described in articles submitted to the
+Editor are first tried out and tested before they are published. This
+important innovation places the standard of the published material very
+high, and it insures accuracy and dependability.
+
+The magazine is the only one in this country that specializes in
+practical model building. Articles in past issues have given
+comprehensive designs for many model boats, including submarines and
+chasers, model steam and gasoline engines, electric motors and
+generators, etc., etc. This feature is a permanent one in this magazine.
+
+Another popular department is that devoted to automobiles and airplanes.
+Care, maintenance, and operation receive full and authoritative
+treatment. Every article is written from the practical, everyday man,
+standpoint rather than from that of the professional.
+
+The magazine entertains while it instructs. It is a journal of
+practical, dependable information given in such a style that it may be
+readily assimilated and applied by the man with little or no technical
+training. The aim is to place before the man who leans toward practical
+mechanics, a series of concise, crisp, readable talks on what is going
+on and _how it is done_. These articles are profusely illustrated with
+clear, snappy photographs, specially posed to illustrate the subject in
+the magazine's own studio by its own staff of technically-trained
+illustrators and editors.
+
+=The subscription price of the magazine is one dollar per year of twelve
+numbers. Sample copy sent on receipt of ten cents.=
+
+Enter your subscription to this practical magazine with your bookseller.
+
+
+=The Norman W. Henley Publishing Co.,=
+
+=2 West 45th Street, New York=
+
+
+
+
+  +-----------------------------------------------------------------+
+  |                      TRANSCRIBER'S NOTES                        |
+  |                                                                 |
+  | General remarks:                                                |
+  |   There are some differences in wording between the Table of    |
+  |   Contents, the lists of sections per chapter, and the actual   |
+  |   section titles. Their meaning is clear, and they have been    |
+  |   left as they were in the original work.                       |
+  |   Page 56, table: Fig. 8 in the first column does not refer to  |
+  |   Fig. 8 in this work.                                          |
+  |   The original work does not have a Figure 89.                  |
+  |   Page 303, table: it is uncertain what "free with kerosene"    |
+  |   means, there may be a word omitted.                           |
+  |   Page 544, entirely censored. It is not clear what this page   |
+  |   originally contained (possibly a table), since text and       |
+  |   numbering of illustrations are uninterrupted. The text        |
+  |   "CENSORED" has been moved to after the first paragraph of the |
+  |   section on Mercedes Engines.                                  |
+  |   The List of Illustrations does not occur in the original work.|
+  |                                                                 |
+  | Changes made:                                                   |
+  |   The text of the original work (including inconsistencies in   |
+  |   accents, spelling, hyphenation and lay-out, and differences   |
+  |   between the main text, illustrations and advertisements) has  |
+  |   been followed, except when listed below. Only some minor      |
+  |   obvious typographical errors have been corrected silently.    |
+  |   Where the author used x for multiplication, this has been     |
+  |   replaced by × in the body of the text (not in the             |
+  |   advertisements or illustrations).                             |
+  |   The illustrations have been moved so as not to disrupt the    |
+  |   flow of the text.                                             |
+  |   Engine and aircraft types are not always named consistently in|
+  |   the original; Curtiss engine O X 2, OX-2 and 0X2 have all     |
+  |   been changed to OX-2, Curtiss aircraft JN4 and JN-4 to JN-4.  |
+  |   Multi-page tables: repeated headings have been removed, and   |
+  |   the tables treated as one consecutive table.                  |
+  |   Page 22: "The product of" has been moved into the first       |
+  |   formula.                                                      |
+  |   Page 25: "When B × r = M" changed to "When P × r = M".        |
+  |   Page 74: ".225 ÷ 775 = .2905" changed to ".225 ÷ .775 =       |
+  |   .2905".                                                       |
+  |   Page 137 (caption): "Bavary" changed to "Baverey" as          |
+  |   elsewhere.                                                    |
+  |   Page 172: "evidently" changed to "evident".                   |
+  |   Page 214: "drop to O" changed to "drop to 0".                 |
+  |   Page 248: "actual from a common" changed to "actuated from a  |
+  |   common".                                                      |
+  |   Page 256: "values" changed to "valves".                       |
+  |   Page 280: "Fig. 6" changed to "Fig. 112".                     |
+  |   Page 306: "Fig. 127, B" changed to "Fig. 127, C" (2nd         |
+  |   reference).                                                   |
+  |   Page 324: "Rhone" changed to "Le Rhone" as elsewhere.         |
+  |   Page 334: "Check values" changed to "Check valves".           |
+  |   Page 364: "LeRhone" changed to "Le Rhone" as elsewhere.       |
+  |   Page 390: "Fig. 62, D" changed to "Fig. 168, B".              |
+  |   Page 408: "Stilson" changed to "Stillson" as elsewhere.       |
+  |   Page 490: "both valves" changed to "both halves".             |
+  |   Page 514: "standard ratio is 5.3" changed to "standard ratio  |
+  |   is 5:3".                                                      |
+  |   Page 529: "gallons per minute 1,400 R. P. M." changed to      |
+  |   "gallons per minute at 1,400 R. P. M."                        |
+  |   Page 546: "Hispano Suiza" changed to "Hispano-Suiza" as       |
+  |   elsewhere.                                                    |
+  |   Page 556: "Diameter of crank-shaft, 56 mm." changed to        |
+  |   "Diameter of crank-shaft, 55 mm."                             |
+  |   Page 7 (advertisements): "Hazlehurst Field" changed to        |
+  |   "Hazelhurst Field".                                           |
+  |   Page 21 (advertisements): "Rhose Island Compound" changed to  |
+  |   "Rhode Island Compound".                                      |
+  |   Index: "Shebler" changed to "Schebler", "camshaft" to         |
+  |   "cam-shaft", "wristpin" to "wrist-pin", etc. (all as in text).|
+  +-----------------------------------------------------------------+
+
+
+
+***END OF THE PROJECT GUTENBERG EBOOK AVIATION ENGINES***
+
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+<h1>The Project Gutenberg eBook, Aviation Engines, by Victor Wilfred Pagé</h1>
+<pre>
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at <a href = "http://www.gutenberg.org">www.gutenberg.org</a></pre>
+<p>Title: Aviation Engines</p>
+<p>       Design--Construction--Operation and Repair</p>
+<p>Author: Victor Wilfred Pagé</p>
+<p>Release Date: December 2, 2011  [eBook #38187]</p>
+<p>Language: English</p>
+<p>Character set encoding: ISO-8859-1</p>
+<p>***START OF THE PROJECT GUTENBERG EBOOK AVIATION ENGINES***</p>
+<p>&nbsp;</p>
+<h3>E-text prepared by Juliet Sutherland, Harry Lamé,<br />
+    and the Online Distributed Proofreading Team<br />
+    (http://www.pgdp.net)</h3>
+<p>&nbsp;</p>
+<div class="bbox" style="margin: 1em 20%; padding: 1em;">
+<p class="center">Please see <a href="#TN">Transcriber&#8217;s Notes</a> at the end of this document.</p>
+</div>
+<p>&nbsp;</p>
+<hr class="full" />
+<p>&nbsp;</p>
+<p>&nbsp;</p>
+<p>&nbsp;</p>
+
+<div class="boxoutside" style="margin: 1.5em 10%;">
+<div class="boxinside">
+<h2><span class="bb2">JUST PUBLISHED</span></h2>
+
+<p><b>AVIATION ENGINES. Their Design, Construction,
+Operation and Repair.</b></p>
+
+<div class="chapsec"><p>By Lieut. <span class="smcap">Victor W. Pag&eacute;</span>, Aviation Section, S.C.U.S.R.</p>
+
+<p>A practical work containing valuable instructions for aviation
+students, mechanicians, squadron engineering officers and all interested
+in the construction and upkeep of airplane power plants.
+576 octavo pages. 250 illustrations. Price $3.00.</p></div>
+
+<p><b>AVIATION CHART, or the Location of Airplane Power
+Plant Troubles Made Easy.</b></p>
+
+<div class="chapsec"><p>By Lieut. <span class="smcap">Victor W. Pag&eacute;</span>, A.S., S.C.U.S.R.</p>
+
+<p>A large chart outlining all parts of a typical airplane power plant,
+showing the points where trouble is apt to occur and suggesting
+remedies for the common defects. Intended especially for aviators
+and aviation mechanics on school and field duty. Price 50 cents.</p></div>
+
+<p><b>GLOSSARY OF AVIATION TERMS.</b></p>
+
+<div class="chapsec"><p>Compiled by Lieuts. <span class="smcap">Victor W. Pag&eacute;</span>, A.S., S.C.U.S.R. and
+<span class="smcap">Paul Montariol</span> of the French Flying Corps on duty at
+Signal Corps Aviation School, Mineola, L. I.</p>
+
+<p>A complete glossary of practically all terms used in aviation,
+having lists in both French and English, with equivalents in either
+language. A very valuable book for all who are about to leave
+for duty overseas. Price, cloth, $1.00.</p></div>
+
+<p class="bb2" style="line-height: .1em; margin: auto 40%;">&nbsp;</p>
+
+<p class="center"><b>THE NORMAN W. HENLEY PUBLISHING COMPANY</b></p>
+
+<p class="center">2 WEST 45<span class="smcap">th</span> ST., NEW YORK</p>
+</div>
+</div>
+
+<div class="figcenter" style="width: 400px; margin-top: 1.5em;"><a name="frontispiece" id="frontispiece"></a>
+<p class="leftlink"><a href="images/large002.png">Large<br />image<br />(105 kB).</a></p>
+<img src="images/illo002.png" alt="Hall-Scott Engine" width="400" height="587"  />
+<p class="caption">Part Sectional View of Hall-Scott Airplane Motor, Showing
+Principal Parts.</p></div>
+
+<div class="boxoutside" style="margin: 1.5em 10%;"><div class="boxinside">
+
+<p class="center fsize150">CENSORED</p>
+
+<p class="center"><i>This Book Entitled</i></p>
+
+<p class="center fsize125">AVIATION ENGINES</p>
+
+<p class="center"><i>By</i> LIEUT. VICTOR W. PAG&Eacute;</p>
+
+<p>has been censored by the United States Government,
+and pages and parts of pages have been
+omitted by special instructions from Washington.</p>
+
+<p>The book has been passed by THE COMMITTEE
+ON PUBLIC INFORMATION and is
+as complete as we can furnish it, and we so
+advise the purchaser of it.</p>
+
+<p class="center">THE NORMAN W. HENLEY PUBLISHING COMPANY</p>
+</div></div>
+
+<div class="boxoutside" style="margin: 1.5em auto;">
+<div class="boxinside">
+<h1>AVIATION ENGINES<br />
+<span class="fsize80"><i>Design&mdash;Construction&mdash;Operation and Repair</i></span></h1>
+</div>
+
+<div class="boxinside" style="margin-top: .25em;">
+<p>A COMPLETE, PRACTICAL TREATISE OUTLINING CLEARLY
+THE ELEMENTS OF INTERNAL COMBUSTION ENGINEERING
+WITH SPECIAL REFERENCE TO THE DESIGN, CONSTRUCTION,
+OPERATION AND REPAIR OF AIRPLANE POWER
+PLANTS; ALSO THE AUXILIARY ENGINE SYSTEMS, SUCH
+AS LUBRICATION, CARBURETION, IGNITION AND COOLING.</p>
+
+<p>IT INCLUDES COMPLETE INSTRUCTIONS FOR ENGINE
+REPAIRING AND SYSTEMATIC LOCATION OF TROUBLES,
+TOOL EQUIPMENT AND USE OF TOOLS, ALSO OUTLINES
+THE LATEST MECHANICAL PROCESSES.</p>
+
+<p class="center fsize80" style="margin-top: 1.5em;">BY</p>
+
+<p class="center" style="margin-top: 1.5em;"><span class="smcap">First Lieut</span>. VICTOR W. PAG&Eacute;, A. S. S. C., U. S. R.</p>
+
+<p class="center fsize80" style="margin-top: 1.5em;">Assistant Engineering Officer, Signal Corps Aviation School, Mineola, L.&nbsp;I.<br />
+Author of &#8220;The Modern Gasoline Automobile,&#8221; Etc.</p>
+
+<div class="figcenter">
+<img src="images/illo004.png" alt="The bright light of science" width="100" height="82" />
+</div>
+
+<p class="center fsize80">CONTAINS VALUABLE INSTRUCTIONS FOR ALL AVIATION STUDENTS, MECHANICIANS,
+SQUADRON ENGINEERING OFFICERS AND ALL INTERESTED IN
+THE CONSTRUCTION AND UPKEEP OF AIRPLANE POWER PLANTS.</p>
+</div>
+
+<div class="boxinside" style="margin-top: .25em;">
+<p class="center">NEW YORK<br />
+THE NORMAN W. HENLEY PUBLISHING COMPANY<br />
+2 <span class="smcap">West 45th Street</span><br />
+1917</p>
+</div>
+</div>
+
+<hr class="c25" />
+
+<div class="boxoutside" style="margin: 2.5em 25%;"><div class="boxinside">
+<p class="center fsize80"><span class="smcap">Copyrighted</span>, 1917<br />
+<span class="smcap">by</span><br />
+<span class="smcap">The Norman W. Henley Publishing Co.</span></p>
+</div></div>
+
+<p class="center fsize80">PRINTED IN U. S. A.</p>
+
+<div class="boxoutside" style="margin: 1.5em;"><div class="boxinside">
+<p class="center fsize80">ALL ILLUSTRATIONS IN THIS BOOK HAVE BEEN
+SPECIALLY MADE BY THE PUBLISHERS, AND THEIR
+USE, WITHOUT PERMISSION, IS STRICTLY PROHIBITED</p>
+</div></div>
+
+<p class="center fsize80" style="margin-top: 1.5em;">COMPOSITION, ELECTROTYPING AND PRESSWORK<br />
+BY THE PUBLISHERS PRINTING CO., NEW YORK</p>
+
+<hr class="c25" />
+<p class='pagenum'><a name="Page_9" id="Page_9">[9]</a></p>
+<h2>PREFACE</h2>
+
+<p>In presenting this treatise on &#8220;Aviation Engines,&#8221;
+the writer realizes that the rapidly developing art makes
+it difficult to outline all latest forms or describe all
+current engineering practice. This exposition has been
+prepared primarily for instruction purposes and is adapted
+for men in the Aviation Section, Signal Corps, and
+students who wish to become aviators or aviation mechanicians.
+Every effort has been made to have the engineering
+information accurate, but owing to the diversity
+of authorities consulted and use of data translated from
+foreign language periodicals, it is expected that some
+slight errors will be present. The writer wishes to acknowledge
+his indebtedness to such firms as the Curtiss
+Aeroplane and Motor Co., Hall-Scott Company, Thomas-Morse
+Aircraft Corporation and General Vehicle Company
+for photographs and helpful descriptive matter.
+Special attention has been paid to instructions on tool
+equipment, use of tools, trouble &#8220;shooting&#8221; and engine
+repairs, as it is on these points that the average aviation
+student is weakest. Only such theoretical consideration
+of thermo-dynamics as was deemed absolutely necessary
+to secure a proper understanding of engine action after
+consulting several instructors is included, the writer&#8217;s
+efforts having been confined to the preparation of a
+practical series of instructions that would be of the
+greatest value to those who need a diversified knowledge
+of internal-combustion engine operation and repair, and<span class='pagenum'><a name="Page_10" id="Page_10">[10]</a></span>
+who must acquire it quickly. The engines described and
+illustrated are all practical forms that have been fitted to
+airplanes capable of making flights and may be considered
+fairly representative of the present state of the art.</p>
+
+<p class="signright"><span class="smcap">Victor W. Pag&eacute;</span>,<br />
+<i>1st Lieut. A. S. S. C., U. S. R.</i></p>
+
+<p class="signleft fsize80"><span class="smcap">Mineola</span>, L. I.,<br />
+October, 1917.</p>
+
+<hr class="c25" />
+<p class='pagenum'><a name="Page_11" id="Page_11">[11]</a></p>
+
+<h2>CONTENTS</h2>
+
+<table style="width: 80%;" summary="ToC">
+
+<tr>
+<td colspan="2" class="center"><a href="#ChI">CHAPTER I</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="2" class="right fsize80">PAGES</td>
+</tr>
+
+<tr>
+<td class="just top"><a href="#SecI_1">Brief Consideration of Aircraft Types</a>&mdash;<a href="#SecI_2">Essential Requirements of Aerial
+Motors</a>&mdash;<a href="#SecI_3">Aviation Engines Must Be Light</a>&mdash;<a href="#SecI_4">Factors Influencing Power
+Needed</a>&mdash;<a href="#SecI_5">Why Explosive Motors Are Best</a>&mdash;<a href="#SecI_6">Historical</a>&mdash;<a href="#SecI_7">Main
+Types of Internal Combustion Engines</a></td>
+<td class="right bot padl1"><a href="#Page_17">17</a>-<a href="#Page_36">36</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="2" class="center"><a href="#ChII">CHAPTER II</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td class="just top"><a href="#SecII_1">Operating Principles of Two- and Four-Stroke Engines</a>&mdash;<a href="#SecII_2">Four-cycle
+Action</a>&mdash;<a href="#SecII_3">Two-cycle Action</a>&mdash;<a href="#SecII_4">Comparing Two- and Four-cycle Types</a>&mdash;<a
+href="#SecII_5">Theory of Gas and Gasoline Engine</a>&mdash;<a href="#SecII_6">Early Gas-Engine Forms</a>&mdash;<a
+href="#SecII_7">Isothermal Law</a>&mdash;<a href="#SecII_8">Adiabatic Law</a>&mdash;<a href="#SecII_9">Temperature
+Computations</a>&mdash;<a href="#SecII_10">Heat and Its Work</a>&mdash;<a href="#SecII_11">Conversion of Heat to Power</a>&mdash;<a
+href="#SecII_12">Requisites for Best Power Effect</a></td>
+<td class="right bot padl1"><a href="#Page_37">37</a>-<a href="#Page_59">59</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="2" class="center"><a href="#ChIII">CHAPTER III</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td class="just top"><a href="#SecIII_1">Efficiency of Internal Combustion Engines</a>&mdash;<a
+href="#SecIII_2">Various Measures of Efficiency</a>&mdash;<a href="#SecIII_3">Temperatures and Pressures</a>&mdash;<a
+href="#SecIII_4">Factors Governing Economy</a>&mdash;<a href="#SecIII_5">Losses in Wall Cooling</a>&mdash;<a href="#SecIII_6">Value of
+Indicator Cards</a>&mdash;<a href="#SecIII_7">Compression in Explosive Motors</a>&mdash;<a href="#SecIII_8">Factors Limiting
+Compression</a>&mdash;<a href="#SecIII_9">Causes of Heat Losses and Inefficiency</a>&mdash;<a href="#SecIII_10">Heat Losses to Cooling
+Water</a></td>
+<td class="right bot padl1"><a href="#Page_60">60</a>-<a href="#Page_79">79</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="2" class="center"><a href="#ChIV">CHAPTER IV</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td class="just top"><a href="#SecIV_1">Engine Parts and Functions</a>&mdash;<a href="#SecIV_2">Why Multiple Cylinder Engines Are
+Best</a>&mdash;<a href="#SecIV_3">Describing Sequence of Operations</a>&mdash;<a href="#SecIV_4">Simple Engines</a>&mdash;<a
+href="#SecIV_5">Four and Six Cylinder Vertical Tandem Engines</a>&mdash;<a href="#SecIV_6">Eight and Twelve Cylinder V
+Engines</a>&mdash;<a href="#SecIV_7">Radial Cylinder Arrangement</a>&mdash;<a href="#SecIV_8">Rotary Cylinder Forms</a></td>
+<td class="right bot padl1"><a href="#Page_80">80</a>-<a href="#Page_109">109</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="2" class="center"><a href="#ChV">CHAPTER V</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td class="just top"><a href="#SecV_1">Properties of Liquid Fuels</a>&mdash;<a href="#SecV_2">Distillates of Crude Petroleum</a>&mdash;<a
+href="#SecV_3">Principles of Carburetion Outlined</a>&mdash;<a href="#SecV_4">Air Needed to Burn Gasoline</a>&mdash;<a href="#SecV_5">What
+a Carburetor Should Do</a>&mdash;<a href="#SecV_6">Liquid Fuel Storage and Supply</a>&mdash;<a href="#SecV_7">Vacuum Fuel
+Feed</a>&mdash;<a href="#SecV_8">Early Vaporizer Forms</a>&mdash;<a href="#SecV_9">Development of Float Feed Carburetor</a>&mdash;<span
+class='pagenum'><a name="Page_12" id="Page_12">[12]</a></span><a href="#SecV_10">Maybach&#8217;s Early Design</a>&mdash;<a
+href="#SecV_11">Concentric Float and Jet Type</a>&mdash;<a href="#SecV_12">Schebler Carburetor</a>&mdash;<a href="#SecV_13">Claudel
+Carburetor</a>&mdash;<a href="#SecV_14">Stewart Metering Pin Type</a>&mdash;<a href="#SecV_15">Multiple Nozzle Vaporizers</a>&mdash;<a
+href="#SecV_16">Two-Stage Carburetor</a>&mdash;<a href="#SecV_17">Master Multiple Jet Type</a>&mdash;<a href="#SecV_18">Compound Nozzle
+Zenith Carburetor</a>&mdash;<a href="#SecV_19">Utility of Gasoline Strainers</a>&mdash;<a href="#SecV_20">Intake Manifold Design and
+Construction</a>&mdash;<a href="#SecV_21">Compensating for Various Atmospheric Conditions</a>&mdash;<a href="#SecV_22">How High Altitude
+Affects Power</a>&mdash;<a href="#SecV_23">The Diesel System</a>&mdash;<a href="#SecV_24">Notes on Carburetor Installation</a>&mdash;<a
+href="#SecV_25">Notes on Carburetor Adjustment</a></td>
+<td class="right bot padl1"><a href="#Page_110">110</a>-<a href="#Page_154">154</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="2" class="center"><a href="#ChVI">CHAPTER VI</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td class="just top"><a href="#SecVI_1">Early Ignition Systems</a>&mdash;<a href="#SecVI_2">Electrical Ignition Best</a>&mdash;<a
+href="#SecVI_3">Fundamentals of Magnetism Outlined</a>&mdash;<a href="#SecVI_4">Forms of Magneto</a>&mdash;<a href="#SecVI_5">Zones of
+Magnetic Influence</a>&mdash;<a href="#SecVI_6">How Magnets are Made</a>&mdash;<a href="#SecVI_7">Electricity and Magnetism
+Related</a>&mdash;<a href="#SecVI_8">Basic Principles of Magneto Action</a>&mdash;<a href="#SecVI_9">Essential Parts of Magneto and
+Functions</a>&mdash;<a href="#SecVI_10">Transformer Coil Systems</a>&mdash;<a href="#SecVI_11">True High Tension Type</a>&mdash;<a
+href="#SecVI_12">The Berling Magneto</a>&mdash;<a href="#SecVI_13a">Timing</a> and <a href="#SecVI_13b">Care</a>&mdash;<a
+href="#SecVI_14">The Dixie Magneto</a>&mdash;<a href="#SecVI_15">Spark-Plug Design and Application</a>&mdash;<a href="#SecVI_16">Two-Spark
+Ignition</a>&mdash;<a href="#SecVI_17">Special Airplane Plug</a></td>
+<td class="right bot padl1"><a href="#Page_155">155</a>-<a href="#Page_200">200</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="2" class="center"><a href="#ChVII">CHAPTER VII</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td class="just top"><a href="#SecVII_1">Why Lubrication Is Necessary</a>&mdash;<a href="#SecVII_2">Friction Defined</a>&mdash;<a
+href="#SecVII_3">Theory of Lubrication</a>&mdash;<a href="#SecVII_4">Derivation of Lubricants</a>&mdash;<a href="#SecVII_5">Properties of
+Cylinder Oils</a>&mdash;<a href="#SecVII_6">Factors Influencing Lubrication System Selection</a>&mdash;<a href="#SecVII_7">Gnome Type
+Engines Use Castor Oil</a>&mdash;<a href="#SecVII_8">Hall-Scott Lubrication System</a>&mdash;<a href="#SecVII_9">Oil Supply by Constant
+Level Splash System</a>&mdash;<a href="#SecVII_10">Dry Crank-Case System Best for Airplane Engines</a>&mdash;<a href="#SecVII_11">Why
+Cooling Systems Are Necessary</a>&mdash;<a href="#SecVII_12">Cooling Systems Generally Applied</a>&mdash;<a href="#SecVII_13">Cooling by
+Positive Pump Circulation</a>&mdash;<a href="#SecVII_14">Thermo-Syphon System</a>&mdash;<a href="#SecVII_15">Direct Air-Cooling
+Methods</a>&mdash;<a href="#SecVII_16">Air-Cooled Engine Design Considerations</a></td>
+<td class="right bot padl1"><a href="#Page_201">201</a>-<a href="#Page_232">232</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="2" class="center"><a href="#ChVIII">CHAPTER VIII</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td class="just top"><a href="#SecVIII_1">Methods of Cylinder Construction</a>&mdash;<a href="#SecVIII_2">Block Castings</a>&mdash;<a
+href="#SecVIII_3">Influence on Crank-Shaft Design</a>&mdash;<a href="#SecVIII_4">Combustion Chamber Design</a>&mdash;<a
+href="#SecVIII_5">Bore and Stroke Ratio</a>&mdash;<a href="#SecVIII_6">Meaning of Piston Speed</a>&mdash;<a href="#SecVIII_7">Advantage of
+Off-Set Cylinders</a>&mdash;<a href="#SecVIII_8">Valve Location of Vital Import</a>&mdash;<a href="#SecVIII_9">Valve Installation
+Practice</a>&mdash;<a href="#SecVIII_10">Valve Design and Construction</a>&mdash;<a href="#SecVIII_11">Valve Operation</a>&mdash;<a
+href="#SecVIII_12">Methods of Driving Cam-Shaft</a>&mdash;<a href="#SecVIII_13">Valve Springs</a>&mdash;<a href="#SecVIII_14">Valve
+Timing</a>&mdash;<a href="#SecVIII_15">Blowing Back</a>&mdash;<a href="#SecVIII_16">Lead Given Exhaust Valve</a>&mdash;<a
+href="#SecVIII_17">Exhaust Closing, Inlet Opening</a>&mdash;<a href="#SecVIII_18">Closing the Inlet Valve</a>&mdash;<a
+href="#SecVIII_19">Time of Ignition</a>&mdash;<a href="#SecVIII_20">How an Engine is Timed</a>&mdash;<a href="#SecVIII_21">Gnome
+&#8220;Monosoupape&#8221; Valve Timing</a>&mdash;<a href="#SecVIII_22">Springless Valves</a>&mdash;<a href="#SecVIII_23">Four Valves per
+Cylinder</a></td>
+<td class="right bot padl1"><a href="#Page_233">233</a>-<a href="#Page_286">286</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="2" class="center"><a href="#ChIX">CHAPTER IX</a><span class='pagenum'><a name="Page_13" id="Page_13">[13]</a></span></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td class="just top"><a href="#SecIX_1">Constructional Details of Pistons</a>&mdash;<a href="#SecIX_2">Aluminum Cylinders and
+Pistons</a>&mdash;<a href="#SecIX_3">Piston Ring Construction</a>&mdash;<a href="#SecIX_4">Leak Proof Piston Rings</a>&mdash;<a
+href="#SecIX_5">Keeping Oil Out of Combustion Chamber</a>&mdash;<a href="#SecIX_6">Connecting Rod Forms</a>&mdash;<a
+href="#SecIX_7">Connecting Rods for Vee Engines</a>&mdash;<a href="#SecIX_8">Cam-Shaft and Crank-Shaft Designs</a>&mdash;<a
+href="#SecIX_9">Ball Bearing Crank-Shafts</a>&mdash;<a href="#SecIX_10">Engine Base Construction</a></td>
+<td class="right bot padl1"><a href="#Page_287">287</a>-<a href="#Page_323">323</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="2" class="center"><a href="#ChX">CHAPTER X</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td class="just top"><a href="#SecX_1">Power Plant Installation</a>&mdash;<a href="#SecX_2">Curtiss OX-2 Engine Mounting and Operating
+Rules</a>&mdash;<a href="#SecX_3">Standard S. A. E. Engine Bed Dimensions</a>&mdash;<a href="#SecX_4">Hall-Scott Engine Installation and
+Operation</a>&mdash;<a href="#SecX_5">Fuel System Rules</a>&mdash;<a href="#SecX_6">Ignition System</a>&mdash;<a href="#SecX_7">Water
+System</a>&mdash;<a href="#SecX_8">Preparations to Start Engine</a>&mdash;<a href="#SecX_9">Mounting Radial and Rotary Engines</a>&mdash;<a
+href="#SecX_10">Practical Hints to Locate Engine Troubles</a>&mdash;<a href="#SecX_11">All Engine Troubles Summarized</a>&mdash;<a
+href="#SecX_12">Location of Engine Troubles Made Easy</a></td>
+<td class="right bot padl1"><a href="#Page_324">324</a>-<a href="#Page_375">375</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="2" class="center"><a href="#ChXI">CHAPTER XI</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td class="just top"><a href="#SecXI_1">Tools for Adjusting and Erecting</a>&mdash;<a href="#SecXI_2">Forms of Wrenches</a>&mdash;<a
+href="#SecXI_3">Use and Care of Files</a>&mdash;<a href="#SecXI_4">Split Pin Removal and Installation</a>&mdash;<a href="#SecXI_5">Complete
+Chisel Set</a>&mdash;<a href="#SecXI_6">Drilling Machines</a>&mdash;<a href="#SecXI_7">Drills, Reamers, Taps and Dies</a>&mdash;<a
+href="#SecXI_8">Measuring Tools</a>&mdash;<a href="#SecXI_9">Micrometer Calipers and Their Use</a>&mdash;<a href="#SecXI_10">Typical Tool
+Outfits</a>&mdash;<a href="#SecXI_11">Special Hall-Scott Tools</a>&mdash;<a href="#SecXI_12">Overhauling Airplane Engines</a>&mdash;<a
+href="#SecXI_13">Taking Engine Down</a>&mdash;<a href="#SecXI_14">Defects in Cylinders</a>&mdash;<a href="#SecXI_15">Carbon Deposits,
+Cause and Prevention</a>&mdash;<a href="#SecXI_16">Use of Carbon Scrapers</a>&mdash;<a href="#SecXI_17">Burning Out Carbon with
+Oxygen</a>&mdash;<a href="#SecXI_18">Repairing Scored Cylinders</a>&mdash;<a href="#SecXI_19">Valve Removal and Inspection</a>&mdash;<a
+href="#SecXI_20">Reseating and Truing Valves</a>&mdash;<a href="#SecXI_21">Valve Grinding Processes</a>&mdash;<a
+href="#SecXI_22">Depreciation in Valve Operating System</a>&mdash;<a href="#SecXI_23">Piston Troubles</a>&mdash;<a href="#SecXI_24">Piston
+Ring Manipulation</a>&mdash;<a href="#SecXI_25">Fitting Piston Rings</a>&mdash;<a href="#SecXI_26">Wrist-Pin Wear</a>&mdash;<a
+href="#SecXI_27">Inspection and Refitting of Engine Bearings</a>&mdash;<a href="#SecXI_28">Scraping Brasses to Fit</a>&mdash;<a
+href="#SecXI_29">Fitting Connecting Rods</a>&mdash;<a href="#SecXI_30">Testing for Bearing Parallelism</a>&mdash;<a
+href="#SecXI_31">Cam-Shafts and Timing Gears</a>&mdash;<a href="#SecXI_32">Precautions in Reassembling Parts</a></td>
+<td class="right bot padl1"><a href="#Page_376">376</a>-<a href="#Page_456">456</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="2" class="center"><a href="#ChXII">CHAPTER XII</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td class="just top"><a href="#SecXII_1">Aviation Engine Types</a>&mdash;<a href="#SecXII_2">Division in Classes</a>&mdash;<a
+href="#SecXII_3">Anzani Engines</a>&mdash;<a href="#SecXII_4">Canton and Unn&eacute; Engine</a>&mdash;<a href="#SecXII_5">Construction of
+Gnome Engines</a>&mdash;<a href="#SecXII_6">&#8220;Monosoupape&#8221; Gnome</a>&mdash;<a href="#SecXII_7">German &#8220;Gnome&#8221;
+Type</a>&mdash;<a href="#SecXII_8">Le Rhone Engine</a>&mdash;<a href="#SecXII_9">Renault Air-Cooled Engine</a>&mdash;<a
+href="#SecXII_10">Simplex Model &#8220;A&#8221; Hispano-Suiza</a>&mdash;<a href="#SecXII_11">Curtiss Aviation Motors</a>&mdash;<a
+href="#SecXII_12">Thomas-Morse Model 88 Engine</a>&mdash;<a href="#SecXII_13">Duesenberg Engine</a>&mdash;<a href="#SecXII_14">Aeromarine
+Six-Cylinder</a>&mdash;<a href="#SecXII_15">Wisconsin Aviation Engines</a>&mdash;<a href="#SecXII_16">Hall-Scott Engines</a>&mdash;<a
+href="#SecXII_17">Mercedes Motor</a>&mdash;<a href="#SecXII_18">Benz Motor</a>&mdash;<a href="#SecXII_19">Austro-Daimler
+Engine</a>&mdash;<a href="#SecXII_20">Sunbeam-Coatalen</a>&mdash;<a href="#SecXII_21">Indicating and Measuring Instruments</a>&mdash;<a
+href="#SecXII_22">Air Starting Systems</a>&mdash;<a href="#SecXII_23">Electric Starting</a>&mdash;<a href="#SecXII_24">Battery
+Ignition</a></td>
+<td class="right bot padl1"><a href="#Page_457">457</a>-<a href="#Page_571">571</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td class="left top"><a href="#Index">INDEX</a></td>
+<td class="right bot padl1"><a href="#Page_573">573</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td class="left top"><a href="#LoI">LIST OF ILLUSTRATIONS</a></td>
+<td>&nbsp;</td>
+</tr>
+
+</table>
+
+<hr class="c25" />
+<p class='pagenum'><a name="Page_17" id="Page_17">[17]</a></p>
+<p class="center"><b><span class="fsize175">AVIATION ENGINES</span><br />
+<span class="fsize125">DESIGN&mdash;CONSTRUCTION&mdash;REPAIR</span></b></p>
+
+<hr class="c25" />
+<h2><a name="ChI" id="ChI"></a>CHAPTER I</h2>
+
+<div class="chapsec"><p><a href="#SecI_1">Brief Consideration of Aircraft Types</a>&mdash;<a href="#SecI_2">Essential Requirements of
+Aerial Motors</a>&mdash;<a href="#SecI_3">Aviation Engines Must Be Light</a>&mdash;<a href="#SecI_4">Factors Influencing
+Power Needed</a>&mdash;<a href="#SecI_5">Why Explosive Motors Are
+Best</a>&mdash;<a href="#SecI_6">Historical</a>&mdash;<a href="#SecI_7">Main
+Types of Internal Combustion Engines</a>.</p></div>
+
+<h3><a name="SecI_1" id="SecI_1"></a>BRIEF CONSIDERATION OF AIRCRAFT TYPES</h3>
+
+<p>The conquest of the air is one of the most stupendous
+achievements of the ages. Human flight opens the sky
+to man as a new road, and because it is a road free of all
+obstructions and leads everywhere, affording the shortest
+distance to any place, it offers to man the prospect of
+unlimited freedom. The aircraft promises to span continents
+like railroads, to bridge seas like ships, to go over
+mountains and forests like birds, and to quicken and
+simplify the problems of transportation. While the actual
+conquest of the air is an accomplishment just being realized
+in our days, the idea and yearning to conquer the air
+are old, possibly as old as intellect itself. The myths of
+different races tell of winged gods and flying men, and
+show that for ages to fly was the highest conception of
+the sublime. No other agent is more responsible for sustained
+flight than the internal combustion motor, and it
+was only when this form of prime mover had been fully
+developed that it was possible for man to leave the ground
+and alight at will, not depending upon the caprices of
+the winds or lifting power of gases as with the balloon.
+It is safe to say that the solution of the problem of flight
+would have been attained many years ago if the proper
+source of power had been available as all the essential<span class='pagenum'><a name="Page_18" id="Page_18">[18]</a></span>
+elements of the modern aeroplane and dirigible balloon,
+other than the power plant, were known to early philosophers
+and scientists.</p>
+
+<p>Aeronautics is divided into two fundamentally different
+branches&mdash;aviatics and aerostatics. The first comprises
+all types of aeroplanes and heavier than air flying
+machines such as the helicopters, kites, etc.; the second
+includes dirigible balloons, passive balloons and all craft
+which rise in the air by utilizing the lifting force of gases.
+Aeroplanes are the only practical form of heavier-than-air
+machines, as the helicopters (machines intended to be
+lifted directly into the air by propellers, without the sustaining
+effect of planes), and ornithopters, or flapping
+wing types, have not been thoroughly developed, and in
+fact, there are so many serious mechanical problems to
+be solved before either of these types of air craft will
+function properly that experts express grave doubts regarding
+the practicability of either. Aeroplanes are divided
+into two main types&mdash;monoplanes or single surface
+forms, and bi-planes or machines having two sets of lifting
+surfaces, one suspended over the other. A third type,
+the triplane, is not very widely used.</p>
+
+<p>Dirigible balloons are divided into three classes: the
+rigid, the semi-rigid, and the non-rigid. The rigid has a
+frame or skeleton of either wood or metal inside of the
+bag, to stiffen it; the semi-rigid is reinforced by a wire
+net and metal attachments; while the non-rigid is just a
+bag filled with gas. The aeroplane, more than the dirigible
+and balloon, stands as the emblem of the conquest of the
+air. Two reasons for this are that power flight is a real
+conquest of the air, a real victory over the battling elements;
+secondly, because the aeroplane, or any flying machine
+that may follow, brings air travel within the reach
+of everybody. In practical development, the dirigible may
+be the steamship of the air, which will render invaluable
+services of a certain kind, and the aeroplane will be the
+automobile of the air, to be used by the multitude, perhaps
+for as many purposes as the automobile is now being used.</p>
+
+<p class='pagenum'><a name="Page_19" id="Page_19">[19]</a></p>
+<h3><a name="SecI_2" id="SecI_2"></a>ESSENTIAL REQUIREMENTS OF AERIAL MOTORS</h3>
+
+<p>One of the marked features of aircraft development has
+been the effect it has had upon the refinement and perfection
+of the internal combustion motor. Without question
+gasoline-motors intended for aircraft are the nearest to
+perfection of any other type yet evolved. Because of the
+peculiar demands imposed upon the aeronautical motor it
+must possess all the features of reliability, economy and
+efficiency now present with automobile or marine engines
+and then must have distinctive points of its own. Owing
+to the unstable nature of the medium through which it is
+operated and the fact that heavier-than-air machines can
+maintain flight only as long as the power plant is functioning
+properly, an airship motor must be more reliable
+than any used on either land or water. While a few
+pounds of metal more or less makes practically no difference
+in a marine motor and has very little effect upon
+the speed or hill-climbing ability of an automobile, an
+airship motor must be as light as it is possible to make
+it because every pound counts, whether the motor is to be
+fitted into an aeroplane or in a dirigible balloon.</p>
+
+<p>Airship motors, as a rule, must operate constantly at
+high speeds in order to obtain a maximum power delivery
+with a minimum piston displacement. In automobiles, or
+motor boats, motors are not required to run constantly at
+their maximum speed. Most aircraft motors must function
+for extended periods at speed as nearly the maximum
+as possible. Another thing that militates against the aircraft
+motor is the more or less unsteady foundation to
+which it is attached. The necessarily light framework of the
+aeroplane makes it hard for a motor to perform at maximum
+efficiency on account of the vibration of its foundation
+while the craft is in flight. Marine and motor car engines,
+while not placed on foundations as firm as those provided
+for stationary power plants, are installed on bases of much
+more stability than the light structure of an aeroplane.
+The aircraft motor, therefore, must be balanced to a nicety<span class='pagenum'><a name="Page_20" id="Page_20">[20]</a></span>
+and must run steadily under the most unfavorable conditions.</p>
+
+<h3><a name="SecI_3" id="SecI_3"></a>AERIAL MOTORS MUST BE LIGHT</h3>
+
+<p>The capacity of light motors designed for aerial work
+per unit of mass is surprising to those not fully conversant
+with the possibilities that a thorough knowledge
+of proportions of parts and the use of special metals
+developed by the automobile industry make possible. Activity
+in the development of light motors has been more
+pronounced in France than in any other country. Some
+of these motors have been complicated types made light
+by the skillful proportioning of parts, others are of the
+refined simpler form modified from current automobile
+practice. There is a tendency to depart from the freakish
+or unconventional construction and to adhere more closely
+to standard forms because it is necessary to have the parts
+of such size that every quality making for reliability,
+efficiency and endurance are incorporated in the design.
+Aeroplane motors range from two cylinders to forms having
+fourteen and sixteen cylinders and the arrangement
+of these members varies from the conventional vertical
+tandem and opposed placing to the V form or the more
+unusual radial motors having either fixed or rotary cylinders.
+The weight has been reduced so it is possible to
+obtain a complete power plant of the revolving cylinder
+air-cooled type that will not weigh more than three pounds
+per actual horse-power and in some cases less than this.</p>
+
+<p>If we give brief consideration to the requirements of
+the aviator it will be evident that one of the most important
+is securing maximum power with minimum mass,
+and it is desirable to conserve all of the good qualities
+existing in standard automobile motors. These are certainty
+of operation, good mechanical balance and uniform
+delivery of power&mdash;fundamental conditions which must be
+attained before a power plant can be considered practical.
+There are in addition, secondary considerations, none the
+less desirable, if not absolutely essential. These are minimum<span class='pagenum'><a name="Page_21" id="Page_21">[21]</a></span>
+consumption of fuel and lubricating oil, which is
+really a factor of import, for upon the economy depends
+the capacity and flying radius. As the amount of liquid
+fuel must be limited the most suitable motor will be that
+which is powerful and at the same time economical. Another
+important feature is to secure accessibility of components
+in order to make easy repair or adjustment of
+parts possible. It is possible to obtain sufficiently light-weight
+motors without radical departure from established
+practice. Water-cooled power plants have been designed
+that will weigh but four or five pounds per horse-power
+and in these forms we have a practical power plant
+capable of extended operation.</p>
+
+<h3><a name="SecI_4" id="SecI_4"></a>FACTORS INFLUENCING POWER NEEDED</h3>
+
+<p>Work is performed whenever an object is moved against
+a resistance, and the amount of work performed depends
+not only on the amount of resistance overcome but also
+upon the amount of time utilized in accomplishing a given
+task. Work is measured in horse-power for convenience.
+It will take one horse-power to move 33,000 pounds one
+foot in one minute or 550 pounds one foot in one second.
+The same work would be done if 330 pounds were moved
+100 feet in one minute. It requires a definite amount of
+power to move a vehicle over the ground at a certain
+speed, so it must take power to overcome resistance of
+an airplane in the air. Disregarding the factor of air
+density, it will take more power as the speed increases
+if the weight or resistance remains constant, or more
+power if the speed remains constant and the resistance
+increases. The airplane is supported by air reaction under
+the planes or lifting surfaces and the value of this
+reaction depends upon the shape of the aerofoil, the
+amount it is tilted and the speed at which it is drawn
+through the air. The angle of incidence or degree of
+wing tilt regulates the power required to a certain degree
+as this affects the speed of horizontal flight as well as the
+resistance. Resistance may be of two kinds, one that is<span class='pagenum'><a name="Page_22" id="Page_22">[22]</a></span>
+necessary and the other that it is desirable to reduce to
+the lowest point possible. There is the wing resistance
+and the sum of the resistances of the rest of the machine
+such as fuselage, struts, wires, landing gear, etc. If we
+assume that a certain airplane offered a total resistance
+of 300 pounds and we wished to drive it through the air
+at a speed of sixty miles per hour, we can find the horse-power
+needed by a very simple computation as follows:</p>
+
+<table class="formula" summary="formula p 22-1">
+
+<tr>
+<td class="center bb">The product of 300 pounds resistance times speed of 88 feet<br />
+per second times 60 seconds in a minute</td>
+<td rowspan="2" class="left">&nbsp;=&nbsp;H.P.&nbsp;needed.</td>
+</tr>
+
+<tr>
+<td class="center">divided by 33,000 foot pounds per minute<br />
+in one horse-power</td>
+</tr>
+
+</table>
+
+<p>The result is the horse-power needed, or</p>
+
+<table class="formula" summary="formula p 22-2">
+
+<tr>
+<td class="center bb">300 &times; 88 &times; 60</td>
+<td rowspan="2" class="left">&nbsp;= 48 H.P.</td>
+</tr>
+
+<tr>
+<td class="center">33,000</td>
+</tr>
+
+</table>
+
+<p>Just as it takes more power to climb a hill than it does
+to run a car on the level, it takes more power to climb
+in the air with an airplane than it does to fly on the level.
+The more rapid the climb, the more power it will take.
+If the resistance remains 300 pounds and it is necessary
+to drive the plane at 90 miles per hour, we merely substitute
+proper values in the above formula and we have</p>
+
+<table class="formula" summary="table p 22-3">
+
+<tr>
+<td class="center bb">300 pounds times 132 feet per second times 60<br />
+seconds in a minute</td>
+<td rowspan="2">&nbsp;= 72 H.P.</td>
+</tr>
+
+<tr>
+<td class="center">33,000 foot pounds per minute in one<br />
+horse-power</td>
+</tr>
+
+</table>
+
+<p>The same results can be obtained by dividing the product
+of the resistance in pounds times speed in feet per second
+by 550, which is the foot-pounds of work done in one
+second to equal one horse-power. Naturally, the amount
+of propeller thrust measured in pounds necessary to drive
+an airplane must be greater than the resistance by a substantial
+margin if the plane is to fly and climb as well.<span class='pagenum'><a name="Page_23" id="Page_23">[23]</a></span>
+The following formul&aelig; were given in &#8220;The Aeroplane&#8221;
+of London and can be used to advantage by those desiring
+to make computations to ascertain power requirements:</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig001" id="Fig001"></a>
+<img src="images/illo018.png" alt="Fig. 1" width="400" height="519" />
+<p class="caption">Fig. 1.&mdash;Diagrams Illustrating Computations for Horse-Power Required for
+Airplane Flight.</p></div>
+
+<p>The thrust of the propeller depends on the power of<span class='pagenum'><a name="Page_24" id="Page_24">[24]</a></span>
+the motor, and on the diameter and pitch of the propeller.
+If the required thrust to a certain machine is known, the
+calculation for the horse-power of the motor should be an
+easy matter.</p>
+
+<p>The required thrust is the sum of three different &#8220;resistances.&#8221;
+The first is the &#8220;drift&#8221; (dynamical head resistance
+of the aerofoils), i.e., tan &#945; &times; lift (<i>L</i>), lift being
+equal to the total weight of machine (<i>W</i>) for horizontal
+flight and &#945; equal to the angle of incidence. Certainly we
+must take the tan &#945; at the maximum <i>K<sub>y</sub></i> value for minimum
+speed, as then the drift is the greatest (<a href="#Fig001">Fig. 1</a>, A).</p>
+
+<p>Another method for finding the drift is <i>D</i> = <i>K</i> &times; <i>AV</i><sup>2</sup>,
+when we take the drift again so as to be greatest.</p>
+
+<p>The second &#8220;resistance&#8221; is the total head resistance
+of the machine, at its maximum velocity. And the third
+is the thrust for climbing. The horse-power for climbing
+can be found out in two different ways. I first propose
+to deal with the method, where we find out the actual
+horse-power wanted for a certain climbing speed to our
+machine, where</p>
+
+<table class="formula" summary="formula p 24-1">
+
+<tr>
+<td rowspan="2" class="left">&nbsp;H.P. =&nbsp;</td>
+<td class="center bb">climbing speed/sec. &times; <i>W</i></td>
+</tr>
+
+<tr>
+<td class="center">550</td>
+</tr>
+
+</table>
+
+<p>In this case we know already the horse-power for climbing,
+and we can proceed with our calculation.</p>
+
+<p>With the other method we shall find out the &#8220;thrust&#8221;
+in pounds or kilograms wanted for climbing and add it
+to drift and total head resistance, and we shall have the
+total &#8220;thrust&#8221; of our machine and we shall denote it
+with <i>T</i>, while thrust for climbing shall be <i>T<sub>c</sub></i>.</p>
+
+<p>The following calculation is at our service to find out
+this thrust for climbing</p>
+
+<table class="formula" summary="formula p 24-2">
+
+<tr>
+<td class="center bb"><i>V<sub>c</sub></i> &times; <i>W</i></td>
+<td rowspan="2" class="left">&nbsp;= H.P.,</td>
+</tr>
+
+<tr>
+<td class="center">550</td>
+</tr>
+
+</table>
+
+<p>thence</p>
+
+<table class="formula" summary="formula p 24-3">
+
+<tr>
+<td rowspan="2" class="left"><i>V<sub>c</sub></i> =&nbsp;</td>
+<td class="center bb">H.P. &times; 550</td>
+<td rowspan="2" class="right" style="padding-left: 10em;">(1)</td>
+</tr>
+
+<tr>
+<td class="center"><i>W</i></td>
+</tr>
+
+</table>
+
+<p class='pagenum'><a name="Page_25" id="Page_25">[25]</a></p>
+
+<table class="formula" summary="formula p 25-1">
+
+<tr>
+<td rowspan="2" class="left">H.P. =&nbsp;</td>
+<td class="center bb"><i>T<sub>c</sub></i> &times; <i>V</i></td>
+<td rowspan="2" class="left">,</td>
+</tr>
+
+<tr>
+<td class="center">550</td>
+</tr>
+
+</table>
+
+<p>then from (1)</p>
+
+<table class="formula" summary="formula p25-2">
+
+<tr>
+<td>&nbsp;</td>
+<td rowspan="2" class="center bb"><table class="formula" style="margin-bottom: 0;" summary="formula p25-2 inside">
+  <tr>
+  <td class="center bb"><i>T<sub>c</sub></i> &times; <i>V</i></td>
+  <td rowspan="2" class="left">&nbsp;&times; 550</td>
+  </tr>
+  <tr>
+  <td class="center">550</td>
+  </tr>
+</table>
+</td>
+<td>&nbsp;</td>
+<td rowspan="2" class="center bot bb"><i>T<sub>c</sub></i> &times; <i>V</i></td>
+</tr>
+
+<tr>
+<td rowspan="2" class="left"><i>V<sub>c</sub></i> =&nbsp;</td>
+<td rowspan="2" class="center">&nbsp;=&nbsp;</td>
+<td rowspan="2" class="left">,</td>
+</tr>
+
+<tr>
+<td class="center"><i>W</i></td>
+<td class="center"><i>W</i></td>
+</tr>
+
+</table>
+
+<p>thence,</p>
+
+<table class="formula" summary="formula p 25-3">
+
+<tr>
+<td rowspan="2" class="left"><i>T<sub>c</sub></i> =&nbsp;</td>
+<td class="center bb"><i>V<sub>c</sub></i> &times; <i>W</i></td>
+<td rowspan="2">.</td>
+</tr>
+
+<tr>
+<td class="center"><i>V</i></td>
+</tr>
+
+</table>
+
+<p>Whether <i>T</i> means drifts, head resistance and thrust
+for climbing, or drift and head resistance only, the following
+calculation is the same, only in the latter case, of
+course, we must add the horse-power required for climbing
+to the result to obtain the total horse-power.</p>
+
+<p>Now, when we know the total thrust, we shall find the
+horse-power in the following manner:</p>
+
+<p>We know that the</p>
+
+<table class="formula" summary="formula p 25-4">
+
+<tr>
+<td rowspan="2" class="left">H.P. =&nbsp;</td>
+<td class="center bb"><i>P r</i> 2&#960; <i>R</i></td>
+</tr>
+
+<tr>
+<td class="center">75 &times; 60</td>
+</tr>
+
+</table>
+
+<p>in kilograms, or in English measure,</p>
+
+<table class="formula" summary="formula p 25-5">
+
+<tr>
+<td rowspan="2" class="left">H.P. =&nbsp;</td>
+<td class="center bb"><i>P r</i> 2&#960; <i>R</i></td>
+<td rowspan="2" class="left">&nbsp;(<a href="#Fig001">Fig. 1</a>, B)</td>
+</tr>
+
+<tr>
+<td class="center">33,000</td>
+</tr>
+
+</table>
+
+<p>where</p>
+
+<table class="formula" summary="formula p25-6">
+
+<tr>
+<td class="left"><i>P</i></td>
+<td class="center">&nbsp;=&nbsp;</td>
+<td class="left">pressure in klgs. or lbs.</td>
+</tr>
+
+<tr>
+<td class="left"><i>r</i></td>
+<td class="center">&nbsp;=&nbsp;</td>
+<td class="left">radius on which <i>P</i> is acting.</td>
+</tr>
+
+<tr>
+<td class="left"><i>R</i></td>
+<td class="center">&nbsp;=&nbsp;</td>
+<td class="left">Revolution/min.</td>
+</tr>
+
+</table>
+
+<p>When <i>P</i> &times; <i>r</i> = <i>M</i>, then</p>
+
+<table class="formula" summary="formula p 25-7">
+
+<tr>
+<td rowspan="2" class="left">H.P. =&nbsp;</td>
+<td class="center bb"><i>M.R.</i>2&#960;</td>
+<td rowspan="2" class="left">,</td>
+</tr>
+
+<tr>
+<td class="center">4,500</td>
+</tr>
+
+</table>
+
+<p>thence,</p>
+
+<table class="formula" summary="formula p 25-8">
+
+<tr>
+<td rowspan="2" class="left"><i>M</i> =&nbsp;</td>
+<td class="center bb">H.P. &times; 4,500</td>
+<td rowspan="2" class="center">&nbsp;=&nbsp;</td>
+<td class="center bb">716.2 H.P.</td>
+<td rowspan="2" class="left">&nbsp;in meter kilograms,</td>
+</tr>
+
+<tr>
+<td class="center"><i>R</i>2&#960;</td>
+<td class="center"><i>R</i></td>
+</tr>
+
+</table>
+
+<p>or in English system</p>
+
+<table class="formula" summary="formula p 25-9">
+
+<tr>
+<td rowspan="2" class="left"><i>M</i> =&nbsp;</td>
+<td class="center bb">H.P. 33,000</td>
+<td rowspan="2" class="center">&nbsp;=&nbsp;</td>
+<td class="center bb">5253.1 H.P.</td>
+<td rowspan="2" class="left">&nbsp;in foot pounds.</td>
+</tr>
+
+<tr>
+<td class="center"><i>R</i>2&#960;</td>
+<td class="center"><i>R</i></td>
+</tr>
+
+</table>
+
+<p>Now the power on the circumference of the propeller
+will be reduced by its radius, so it will be <i>M</i>/<i>r</i> = <i>p</i>. A
+part<span class='pagenum'><a name="Page_26" id="Page_26">[26]</a></span>
+of <i>p</i> will be used for counteracting the air and bearing friction,
+so that the total power on the circumference of the
+propeller will be (<i>M</i>/<i>r</i>) &times; &#951; = <i>p</i> where &#951; is the mechanical
+efficiency of the propeller. Now &#951;/<i>tan</i> &#945; = <i>T</i>, where &#945; is taken
+on the tip of the propeller.</p>
+
+<p>I take &#945; at the tip, but it can be taken, of course, at any
+point, but then in equation <i>p</i> = <i>M</i>/<i>r</i>, <i>r</i> must be taken only up
+to this point, and not the whole radius; but it is more comfortable
+to take it at the tip, as <i>tan</i> &#945; = Pitch/<i>r</i>2&#960; (<a href="#Fig001">Fig. 1</a>, C).</p>
+
+<p>Now we can write up the equation of the thrust:</p>
+
+<table class="formula" summary="formula p 26-1">
+
+<tr>
+<td rowspan="2" class="left"><i>T</i> =&nbsp;</td>
+<td class="center bb">716.2 H.P. &#951;</td>
+<td rowspan="2" class="left">,&nbsp;or in English measure&nbsp;</td>
+<td class="center bb">5253.1 H.P. &#951;</td>
+<td rowspan="2" class="left">,</td>
+</tr>
+
+<tr>
+<td class="center"><i>R r tan</i> &#945;</td>
+<td class="center"><i>R r tan</i> &#945;</td>
+</tr>
+
+</table>
+
+<p>thence</p>
+
+<table class="formula" summary="formula p 26-2">
+
+<tr>
+<td rowspan="2" class="left">H.P. =&nbsp;</td>
+<td class="center bb"><i>T</i> &times; <i>R</i> &times; <i>r tan</i> &#945;</td>
+<td rowspan="2" class="left">,&nbsp;or in English measure&nbsp;</td>
+<td class="center bb"><i>T</i> &times; <i>R</i> &times; <i>r tan</i> &#945;</td>
+<td rowspan="2" class="left">.</td>
+</tr>
+
+<tr>
+<td class="center">716.2 &#951;</td>
+<td class="center">5253.1 &#951;</td>
+</tr>
+
+</table>
+
+<p>The computations and formul&aelig; given are of most value
+to the student engineer rather than matters of general
+interest, but are given so that a general idea may be
+secured of how airplane design influences power needed
+to secure sustained flight. It will be apparent that the
+resistance of an airplane depends upon numerous considerations
+of design which require considerable research
+in aerodynamics to determine accurately. It is obvious
+that the more resistance there is, the more power needed
+to fly at a given speed. Light monoplanes have been
+flown with as little as 15 horse-power for short distances,<span class='pagenum'><a name="Page_27" id="Page_27">[27]</a></span>
+but most planes now built use engines of 100 horse-power
+or more. Giant airplanes have been constructed having
+2,000 horse-power distributed in four power units. The
+amount of power provided for an airplane of given design
+varies widely as many conditions govern this, but it will
+range from approximately one horse-power to each 8
+pounds weight in the case of very light, fast machines
+to one horse-power to 15 or 18 pounds of the total weight
+in the case of medium speed machines. The development
+in airplane and power plant design is so rapid, however,
+that the figures given can be considered only in the light
+of general averages rather than being typical of current
+practice.</p>
+
+<h3><a name="SecI_5" id="SecI_5"></a>WHY EXPLOSIVE MOTORS ARE BEST</h3>
+
+<p>Internal combustion engines are best for airplanes and
+all types of aircraft for the same reasons that they are
+universally used as a source of power for automobiles.
+The gasoline engine is the lightest known form of prime
+mover and a more efficient one than a steam engine, especially
+in the small powers used for airplane propulsion.
+It has been stated that by very careful designing
+a steam plant an engine could be made that would be
+practical for airplane propulsion, but even with the latest
+development it is doubtful if steam power can be utilized
+in aircraft to as good advantage as modern gasoline-engines
+are. While the steam-engine is considered very
+much simpler than a gas-motor, the latter is much more
+easily mastered by the non-technical aviator and certainly
+requires less attention. A weight of 10 pounds per horse-power
+is possible in a condensing steam plant but this
+figure is nearly double or triple what is easily secured
+with a gas-motor which may weigh but 5 pounds per horse-power
+in the water cooled forms and but 2 or 3 pounds
+in the air-cooled types. The fuel consumption is twice
+as great in a steam-power plant (owing to heat losses)
+as would be the case in a gasoline engine of equal power
+and much less weight.</p>
+
+<p><span class='pagenum'><a name="Page_28" id="Page_28">[28]</a></span>The internal-combustion engine has come seemingly
+like an avalanche of a decade; but it has come to stay,
+to take its well-deserved position among the powers for
+aiding labor. Its ready adaptation to road, aerial and
+marine service has made it a wonder of the age in the
+development of speed not before dreamed of as a possibility;
+yet in so short a time, its power for speed has
+taken rank on the common road against the locomotive
+on the rail with its century&#8217;s progress. It has made aerial
+navigation possible and practical, it furnishes power for
+all marine craft from the light canoe to the transatlantic
+liner. It operates the machine tools of the mechanic, tills
+the soil for the farmer and provides healthful recreation
+for thousands by furnishing an economical means of transport
+by land and sea. It has been a universal mechanical
+education for the masses, and in its present forms represents
+the great refinement and development made possible
+by the concentration of the world&#8217;s master minds on the
+problems incidental to internal combustion engineering.</p>
+
+<h3><a name="SecI_6" id="SecI_6"></a>HISTORICAL</h3>
+
+<p>Although the ideal principle of explosive power was
+conceived some two hundred years ago, at which time
+experiments were made with gunpowder as the explosive
+element, it was not until the last years of the eighteenth
+century that the idea took a patentable shape, and not
+until about 1826 (Brown&#8217;s gas-vacuum engine) that a further
+progress was made in England by condensing the
+products of combustion by a jet of water, thus creating
+a partial vacuum.</p>
+
+<p>Brown&#8217;s was probably the first explosive engine that
+did real work. It was clumsy and unwieldy and was soon
+relegated to its place among the failures of previous experiments.
+No approach to active explosive effect in a
+cylinder was reached in practice, although many ingenious
+designs were described, until about 1838 and the following
+years. Barnett&#8217;s engine in England was the first attempt
+to compress the charge before exploding. From this time<span class='pagenum'><a name="Page_29" id="Page_29">[29]</a></span>
+on to about 1860 many patents were issued in Europe and
+a few in the United States for gas-engines, but the progress
+was slow, and its practical introduction for power
+came with spasmodic effect and low efficiency. From 1860
+on, practical improvement seems to have been made, and
+the Lenoir motor was produced in France and brought
+to the United States. It failed to meet expectations, and
+was soon followed by further improvements in the Hugon
+motor in France (1862), followed by Beau de Rocha&#8217;s
+four-cycle idea, which has been slowly developed through
+a long series of experimental trials by different inventors.
+In the hands of Otto and Langdon a further progress was
+made, and numerous patents were issued in England,
+France, and Germany, and followed up by an increasing
+interest in the United States, with a few patents.</p>
+
+<p>From 1870 improvements seem to have advanced at
+a steady rate, and largely in the valve-gear and precision
+of governing for variable load. The early idea of the necessity
+of slow combustion was a great drawback in the
+advancement of efficiency, and the suggestion of de Rocha
+in 1862 did not take root as a prophetic truth until many
+failures and years of experience had taught the fundamental
+axiom that rapidity of action in both combustion
+and expansion was the basis of success in explosive motors.</p>
+
+<p>With this truth and the demand for small and safe
+prime movers, the manufacture of gas-engines increased
+in Europe and America at a more rapid rate, and improvements
+in perfecting the details of this cheap and efficient
+prime mover have finally raised it to the dignity of a
+standard motor and a dangerous rival of the steam-engine
+for small and intermediate powers, with a prospect of
+largely increasing its individual units to many hundred,
+if not to the thousand horse-power in a single cylinder.
+The unit size in a single cylinder has now reached to about
+700 horse-power and by combining cylinders in the same
+machine, powers of from 1,500 to 2,000 horse-power are
+now available for large power-plants.</p>
+
+<p class='pagenum'><a name="Page_30" id="Page_30">[30]</a></p>
+
+<h3><a name="SecI_7" id="SecI_7"></a>MAIN TYPES OF INTERNAL-COMBUSTION ENGINES</h3>
+
+<p>This form of prime mover has been built in so many
+different types, all of which have operated with some
+degree of success that the diversity in form will not be
+generally appreciated unless some attempt is made to
+classify the various designs that have received practical
+application. Obviously the same type of engine is not
+universally applicable, because each class of work has
+individual peculiarities which can best be met by an engine
+designed with the peculiar conditions present in view.
+The following tabular synopsis will enable the reader to
+judge the extent of the development of what is now the
+most popular prime mover for all purposes.</p>
+
+<table class="ind5" style="line-height: 1em;" summary="table p 30-31">
+
+<tr>
+<td class="left" style="width: 2em;">A.</td>
+<td colspan="3" class="left">Internal Combustion (Standard Type)</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left" style="width: 2em;">1.</td>
+<td colspan="2" class="left">Single Acting (Standard Type)</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">2.</td>
+<td colspan="2" class="left">Double Acting (For Large Power Only)</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">3.</td>
+<td colspan="2" class="left">Simple (Universal Form)</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">4.</td>
+<td colspan="2" class="left">Compound (Rarely Used)</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">5.</td>
+<td colspan="2" class="left">Reciprocating Piston (Standard Type)</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">6.</td>
+<td colspan="2" class="left">Turbine (Revolving Rotor, not fully developed)</td>
+</tr>
+
+<tr>
+<td colspan="4" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td class="left">A1.</td>
+<td colspan="3" class="left">Two-Stroke Cycle</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">a.</td>
+<td colspan="2" class="left">Two Port</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">b.</td>
+<td colspan="2" class="left">Three Port</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">c.</td>
+<td colspan="2" class="left">Combined Two and Three Port</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">d.</td>
+<td colspan="2" class="left">Fourth Port Accelerator</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">e.</td>
+<td colspan="2" class="left">Differential Piston Type</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">f.</td>
+<td colspan="2" class="left">Distributor Valve System</td>
+</tr>
+
+<tr>
+<td colspan="4" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td class="left">A2.</td>
+<td colspan="3" class="left">Four-Stroke Cycle</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">a.</td>
+<td colspan="2" class="left">Automatic Inlet Valve</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">b.</td>
+<td colspan="2" class="left">Mechanical Inlet Valve</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">c.</td>
+<td colspan="2" class="left">Poppet or Mushroom Valve</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">d.</td>
+<td colspan="2" class="left">Slide Valve</td>
+</tr>
+
+<tr>
+<td colspan="2">&nbsp;</td>
+<td class="left" style="width: 2em;">d 1.</td>
+<td class="left">Sleeve Valve</td>
+</tr>
+
+<tr>
+<td colspan="2">&nbsp;</td>
+<td class="left">d 2.</td>
+<td class="left">Reciprocating Ring Valve</td>
+</tr>
+
+<tr>
+<td colspan="2">&nbsp;</td>
+<td class="left">d 3.</td>
+<td class="left">Piston Valve<span class='pagenum'><a name="Page_31" id="Page_31">[31]</a></span></td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">e.</td>
+<td colspan="2" class="left">Rotary Valves</td>
+</tr>
+
+<tr>
+<td colspan="2">&nbsp;</td>
+<td class="left">e 1.</td>
+<td class="left">Disc</td>
+</tr>
+
+<tr>
+<td colspan="2">&nbsp;</td>
+<td class="left">e 2.</td>
+<td class="left">Cylinder or Barrel</td>
+</tr>
+
+<tr>
+<td colspan="2">&nbsp;</td>
+<td class="left">e 3.</td>
+<td class="left">Single Cone</td>
+</tr>
+
+<tr>
+<td colspan="2">&nbsp;</td>
+<td class="left">e 4.</td>
+<td class="left">Double Cone</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">f.</td>
+<td colspan="2" class="left">Two Piston (Balanced Explosion)</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">g.</td>
+<td colspan="2" class="left">Rotary Cylinder, Fixed Crank (Aerial)</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">h.</td>
+<td colspan="2" class="left">Fixed Cylinder, Rotary Crank (Standard Type)</td>
+</tr>
+
+<tr>
+<td colspan="4" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td class="left">A3.</td>
+<td colspan="3" class="left">Six-Stroke Cycle</td>
+</tr>
+
+<tr>
+<td colspan="4" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td class="left">B.</td>
+<td colspan="3" class="left">External Combustion (Practically Obsolete)</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">a.</td>
+<td colspan="2" class="left">Turbine, Revolving Rotor</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">b.</td>
+<td colspan="2" class="left">Reciprocating Piston</td>
+</tr>
+
+</table>
+
+<h3>CLASSIFICATION BY CYLINDER ARRANGEMENT</h3>
+
+<table class="ind5" style="line-height: 1em;" summary="table p 31-32">
+
+<tr>
+<td colspan="3" class="left">Single Cylinder</td>
+</tr>
+
+<tr>
+<td style="width: 2em;">&nbsp;</td>
+<td class="left" style="width: 2em;">a.</td>
+<td class="left">Vertical</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">b.</td>
+<td class="left">Horizontal</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">c.</td>
+<td class="left">Inverted Vertical</td>
+</tr>
+
+<tr>
+<td colspan="3" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="3" class="left">Double Cylinder</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">a.</td>
+<td class="left">Vertical</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">b.</td>
+<td class="left">Horizontal (Side by Side)</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">c.</td>
+<td class="left">Horizontal (Opposed)</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">d.</td>
+<td class="left">45 to 90 Degrees V (Angularly Disposed)</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">e.</td>
+<td class="left">Horizontal Tandem (Double Acting)</td>
+</tr>
+
+<tr>
+<td colspan="3" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="3" class="left">Three Cylinder</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">a.</td>
+<td class="left">Vertical</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">b.</td>
+<td class="left">Horizontal</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">c.</td>
+<td class="left">Rotary (Cylinders Spaced at 120 Degrees)</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">d.</td>
+<td class="left">Radially Placed (Stationary Cylinders)</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">e.</td>
+<td class="left">One Vertical, One Each Side at an Angle</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">f.</td>
+<td class="left">Compound (Two High Pressure, One Low Pressure)</td>
+</tr>
+
+<tr>
+<td colspan="3" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="3" class="left">Four Cylinder</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">a.</td>
+<td class="left">Vertical</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">b.</td>
+<td class="left">Horizontal (Side by Side)<span class='pagenum'><a name="Page_32" id="Page_32">[32]</a></span></td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">c.</td>
+<td class="left">Horizontal (Two Pairs Opposed)</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">d.</td>
+<td class="left">45 to 90 Degrees V</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">e.</td>
+<td class="left">Twin Tandem (Double Acting)</td>
+</tr>
+
+<tr>
+<td colspan="3" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="3" class="left">Five Cylinder</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">a.</td>
+<td class="left">Vertical (Five Throw Crankshaft)</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">b.</td>
+<td class="left">Radially Spaced at 72 Degrees (Stationary)</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">c.</td>
+<td class="left">Radially Placed Above Crankshaft (Stationary)</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">d.</td>
+<td class="left">Placed Around Rotary Crankcase (72 Degrees Spacing)</td>
+</tr>
+
+<tr>
+<td colspan="3" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="3" class="left">Six Cylinder</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">a.</td>
+<td class="left">Vertical</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">b.</td>
+<td class="left">Horizontal (Three Pairs Opposed)</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">c.</td>
+<td class="left">45 to 90 Degrees V</td>
+</tr>
+
+<tr>
+<td colspan="3" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="3" class="left">Seven Cylinder</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">a.</td>
+<td class="left">Equally Spaced (Rotary)</td>
+</tr>
+
+<tr>
+<td colspan="3" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="3" class="left">Eight Cylinder</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">a.</td>
+<td class="left">Vertical</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">b.</td>
+<td class="left">Horizontal (Four Pairs Opposed)</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">c.</td>
+<td class="left">45 to 90 Degrees V</td>
+</tr>
+
+<tr>
+<td colspan="3" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="3" class="left">Nine Cylinder</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">a.</td>
+<td class="left">Equally Spaced (Rotary)</td>
+</tr>
+
+<tr>
+<td colspan="3" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="3" class="left">Twelve Cylinder</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">a.</td>
+<td class="left">Vertical</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">b.</td>
+<td class="left">Horizontal (Six Pairs Opposed)</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">c.</td>
+<td class="left">45 to 90 Degrees V</td>
+</tr>
+
+<tr>
+<td colspan="3" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="3" class="left">Fourteen Cylinder</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">a.</td>
+<td class="left">Rotary</td>
+</tr>
+
+<tr>
+<td colspan="3" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="3" class="left">Sixteen Cylinder</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">a.</td>
+<td class="left">45 to 90 Degrees V</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">b.</td>
+<td class="left">Horizontal (Eight Pairs Opposed)</td>
+</tr>
+
+<tr>
+<td colspan="3" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="3" class="left">Eighteen Cylinder</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left">a.</td>
+<td class="left">Rotary Cylinder</td>
+</tr>
+
+</table>
+
+<p class='pagenum'><a name="Page_33" id="Page_33">[33]</a></p>
+
+<table class ="bt br bb bl" style="width: 650px; margin-top: 2.5em;" summary="Fig. 2">
+
+<tr>
+<td colspan="6" class="figcenter"><a name="Fig002" id="Fig002"></a>
+<img src="images/illo028a.png" alt="Fig. 2a" width="600" height="186" /></td>
+</tr>
+
+<tr>
+<td colspan="6" class="subcaption" style="width: 600px;">Two-Cylinder, Double Acting, Four Cycle Engine for Blast Furnace Gas Fuel<br />
+Weight 600 Pounds per Horsepower<br />
+Very slow speed, made in sizes up to 2000 Horsepower. 60 to 100 R.P.M.</td>
+</tr>
+
+<tr>
+<td colspan="6" class="figcenter">
+<img src="images/illo028b.png" alt="Fig. 2b" width="550" height="169" /></td>
+</tr>
+
+<tr>
+<td colspan="6" class="subcaption" style="width: 550px;">Two Cylinder Opposed Gas Engine&mdash;150 to 650 Horsepower Sizes.<br />
+500 to 600 Pounds per Horsepower. 90 to 100 R.P.M.</td>
+</tr>
+
+<tr>
+<td colspan="3" class="figcenter">
+<img src="images/illo028c.png" alt="Fig. 2c" width="300" height="417" /></td>
+<td colspan="3" class="figcenter">
+<img src="images/illo028d.png" alt="Fig. 2d" width="300" height="438" /></td>
+</tr>
+
+<tr>
+<td colspan="2" class="subcaption" style="width: 250px;">Stationary Diesel Engine<br />
+450 to 500 Pounds per
+Horsepower</td>
+<td colspan="2" class="subcaption" style="width: 150px;">Speed
+Approximately<br />
+200 R.P.M.</td>
+<td colspan="2" class="subcaption" style="width: 250px;">Stationary Gas Engine<br />
+Four Cycle&mdash;Two Cylinder
+300 Pounds per Horsepower</td>
+</tr>
+
+</table>
+
+<p class="caption" style="width: 600px; margin: auto;">Fig. 2.&mdash;Plate Showing Heavy, Slow Speed Internal Combustion Engines
+Used Only for Stationary Power in Large Installations Giving Weight
+to Horse-Power Ratio.</p>
+
+<p class='pagenum'><a name="Page_34" id="Page_34">[34]</a></p>
+
+<table class="bt br bb bl" style="width: 650px; margin-top: 2.5em;" summary="Fig. 3">
+
+<tr>
+<td colspan="2" class="figcenter"><a name="Fig003" id="Fig003"></a>
+<img src="images/illo029a.png" alt="Fig. 3a" width="550" height="297" /></td>
+</tr>
+
+<tr>
+<td colspan="2" class="subcaption" style="width: 500px;">Four Cylinder Diesel Engine for Marine Use<br />
+250 Pounds per Horsepower</td>
+</tr>
+
+<tr>
+<td rowspan="3" class="figcenter">
+<img src="images/illo029b.png" alt="Fig. 3b" width="250" height="382"  /></td>
+<td class="figcenter">
+<img src="images/illo029c.png" alt="Fig. 3c" width="250" height="259"  /></td>
+</tr>
+
+<tr>
+<td class="subcaption" style="width: 250px;">Two Cycle Marine Engine<br />
+50-100 Pounds per Horsepower<br />
+600-800 R.P.M.</td>
+</tr>
+
+<tr>
+<td rowspan="3" class="figcenter">
+<img src="images/illo029d.png" alt="Fig. 3d" width="250" height="175" /></td>
+</tr>
+
+<tr>
+<td class="subcaption" style="width: 250px;">Single Cylinder Vertical Farm Engine<br />
+150 Pounds per Horsepower&mdash;Speed 400 R.P.M.</td>
+</tr>
+
+<tr>
+<td rowspan="3" class="figcenter">
+<img src="images/illo029e.png" alt="Fig. 3e" width="300" height="187" /></td>
+</tr>
+
+<tr>
+<td class="subcaption" style="width: 300px; text-align: center;">Two Cylinder Four Cycle Tractor Engine<br />
+75 Pounds per Horsepower<br />
+800 to 1000 R.P.M.</td>
+</tr>
+
+<tr>
+<td class="subcaption" style="width: 300px; text-align: left;">Four Cylinder Four Cycle Automobile Power Plant<br />
+Weighs about 25 Pounds per Horsepower<br />
+1200 to 2000 R.P.M.</td>
+</tr>
+
+</table>
+
+<p class="caption" style="width: 600px; margin: auto;">Fig. 3.&mdash;Various Forms of Internal Combustion Engines Showing Decrease
+in Weight to Horse-Power Ratio with Augmenting Speed of Rotation.</p>
+
+<p class='pagenum'><a name="Page_35" id="Page_35">[35]</a></p>
+
+<table class="bt br bb bl" style="width: 650px; margin-top: 2.5em;" summary="Fig. 4">
+
+<tr>
+<td class="figcenter"><a name="Fig004" id="Fig004"></a>
+<img src="images/illo030a.png" alt="Fig. 4a" width="250" height="251" /></td>
+<td class="figcenter">
+<img src="images/illo030b.png" alt="Fig. 4b" width="250" height="336" /></td>
+</tr>
+
+<tr>
+<td class="subcaption" style="width: 250px;">Eight Cylinder &#8220;Vee&#8221; Automobile Engine<br />
+15 to 18 Pounds per Horsepower<br />
+Speeds 1500 to 2000 R.P.M</td>
+<td class="subcaption" style="width: 250px;">Two Cylinder Air Cooled Motorcycle<br />
+Engine weights 8-10 Pounds Horsepower<br />
+Speed 3000 R.P.M.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="figcenter">
+<img src="images/illo030c.png" alt="Fig. 4c" width="500" height="249" /></td>
+</tr>
+
+<tr>
+<td colspan="2" class="subcaption" style="width: 500px;">Six, Eight or Twelve Cylinder Water Cooled Aviation Engine, Tandem or V Form<br />
+4 to 6 Pounds per Horsepower<br />
+Speed 1500 R.P.M. Direct Coupled&mdash;2000 R.P.M. Geared Drive</td>
+</tr>
+
+<tr>
+<td class="figcenter">
+<img src="images/illo030d.png" alt="Fig. 4d" width="250" height="195" /></td>
+<td class="figcenter">
+<img src="images/illo030e.png" alt="Fig. 4e" width="250" height="163" /></td>
+</tr>
+
+<tr>
+<td class="subcaption" style="width: 250px;">Seven or Nine Cylinder Revolving<br />
+Air Cooled<br />
+Speed 1200 R.P.M. 2.8 Pounds per Horsepower</td>
+<td class="subcaption" style="width: 250px;">Fourteen or Eighteen Cylinder<br />
+Revolving Air Cooled Aviation Engine<br />
+Speed 1200 R.P.M.<br />
+2 Pounds per Horsepower</td>
+</tr>
+
+</table>
+
+<p class="caption" style="width: 600px; margin: auto;">Fig. 4.&mdash;Internal Combustion Engine Types of Extremely Fine Construction
+and Refined Design, Showing Great Power Outputs for Very Small
+Weight, a Feature Very Much Desired in Airplane Power Plants.</p>
+
+<p><span class='pagenum'><a name="Page_36" id="Page_36">[36]</a></span>Of all the types enumerated above engines having less
+than eight cylinders are the most popular in everything
+but aircraft work. The four-cylinder vertical is without
+doubt the most widely used of all types owing to the
+large number employed as automobile power plants.
+Stationary engines in small and medium powers are invariably
+of the single or double form. Three-cylinder
+engines are seldom used at the present time, except in
+marine work and in some stationary forms. Eight- and
+twelve-cylinder motors have received but limited application
+and practically always in automobiles, racing motor
+boats or in aircraft. The only example of a fourteen-cylinder
+motor to be used to any extent is incorporated
+in aeroplane construction. This is also true of the sixteen- and
+eighteen-cylinder forms and of twenty-four-cylinder
+engines now in process of development.</p>
+
+<p>The duty an engine is designed for determines the
+weight per horse-power. High powered engines intended
+for steady service are always of the slow speed type and
+consequently are of very massive construction. Various
+forms of heavy duty type stationary engines are shown
+at <a href="#Fig002">Fig. 2</a>. Some of these engines may weigh as much as
+600 pounds per horse-power. A further study is possible
+by consulting data given on <a href="#Fig003">Figs. 3</a> and <a href="#Fig004">4</a>. As the crank-shaft
+speed increases and cylinders are multiplied the
+engines become lighter. While the big stationary power
+plants may run for years without attention, airplane engines
+require rebuilding after about 60 to 80 hours air
+service for the fixed cylinder types and 40 hours or less
+for the rotary cylinder air-cooled forms. There is evidently
+a decrease in durability and reliability as the
+weight is lessened. These illustrations also permit of
+obtaining a good idea of the variety of forms internal
+combustion engines are made in.</p>
+
+<hr class="c25" />
+<p class='pagenum'><a name="Page_37" id="Page_37">[37]</a></p>
+<h2><a name="ChII" id="ChII"></a>CHAPTER II</h2>
+
+<div class="chapsec"><p><a href="#SecII_1">Operating Principles of Two- and Four-Stroke Engines</a>&mdash;<a href="#SecII_2">Four-cycle
+Action</a>&mdash;<a href="#SecII_3">Two-cycle Action</a>&mdash;<a href="#SecII_4">Comparing
+Two- and Four-cycle Types</a>&mdash;<a href="#SecII_5">Theory
+of Gas and Gasoline Engine</a>&mdash;<a href="#SecII_6">Early Gas-Engine Forms</a>&mdash;<a href="#SecII_7">Isothermal
+Law</a>&mdash;<a href="#SecII_8">Adiabatic Law</a>&mdash;<a href="#SecII_9">Temperature Computations</a>&mdash;<a href="#SecII_10">Heat
+and Its Work</a>&mdash;<a href="#SecII_11">Conversion of Heat to Power</a>&mdash;<a href="#SecII_12">Requisites
+for Best Power Effect</a>.</p></div>
+
+<h3><a name="SecII_1" id="SecII_1"></a>OPERATING PRINCIPLES OF TWO- AND FOUR-STROKE
+CYCLE ENGINES</h3>
+
+<p>Before discussing the construction of the various forms
+of internal combustion engines it may be well to describe
+the operating cycle of the types most generally used.
+The two-cycle engine is the simplest because there are no
+valves in connection with the cylinder, as the gas is introduced
+into that member and expelled from it through
+ports cored into the cylinder walls. These are covered by
+the piston at a certain portion of its travel and uncovered
+at other parts of its stroke. In the four-cycle engine
+the explosive gas is admitted to the cylinder through a
+port at the head end closed by a valve, while the exhaust
+gas is expelled through another port controlled in a similar
+manner. These valves are operated by mechanism
+distinct from the piston.</p>
+
+<div class="figcenter" style="width: 500px; margin: auto;"><a name="Fig005" id="Fig005"></a>
+<img src="images/illo033.png" alt="Fig. 5" width="500" height="533" />
+<p class="caption">Fig. 5.&mdash;Outlining First Two Strokes of Piston in Four-Cycle Engine.</p></div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig006" id="Fig006"></a>
+<img src="images/illo034.png" alt="Fig. 6" width="500" height="538" />
+<p class="caption">Fig. 6.&mdash;Outlining Second Two Strokes of Piston in Four-Cycle Engine.</p></div>
+
+<p><a name="SecII_2" id="SecII_2"></a>The action of the four-cycle type may be easily understood
+if one refers to illustrations at <a href="#Fig005">Figs. 5</a> and <a href="#Fig006">6</a>. It
+is called the &#8220;four-stroke engine&#8221; because the piston must
+make four strokes in the cylinder for each explosion or
+power impulse obtained. The principle of the gas-engine
+of the internal combustion type is similar to that of a
+gun, i.e., power is obtained by the rapid combustion of
+some explosive or other quick burning substance. The
+bullet is driven out of the gun barrel by the pressure of
+the gas evolved when the charge of powder is ignited.
+The piston or movable element of the gas-engine is driven<span class='pagenum'><a name="Page_38" id="Page_38">[38]</a></span>
+from the closed or head end to the crank end of the
+cylinder by a similar expansion of gases resulting from
+combustion. The first operation in firing a gun or securing
+an explosion in the cylinder of the gas-engine is to
+fill the combustion space with combustible material. This
+is done by a down stroke of the piston during which time
+the inlet valve opens to admit the gaseous charge to the
+cylinder interior. This operation is shown at <a href="#Fig005">Fig. 5</a>, A.
+The second operation is to compress this gas which is
+done by an upward stroke of the piston as shown at<span class='pagenum'><a name="Page_39" id="Page_39">[39]</a></span>
+<a href="#Fig005">Fig. 5</a>, B. When the top of the compression stroke is reached,
+the gas is ignited and the piston is driven down toward
+the open end of the cylinder, as indicated at <a href="#Fig006">Fig. 6</a>, C. The
+fourth operation or exhaust stroke is performed by the
+return upward movement of the piston as shown at <a href="#Fig006">Fig.
+6</a>, D during which time the exhaust valve is opened to
+permit the burnt gases to leave the cylinder. As soon
+as the piston reaches the top of its exhaust stroke, the
+energy stored in the fly-wheel rim during the power stroke
+causes that member to continue revolving and as the piston<span class='pagenum'><a
+name="Page_41" id="Page_41">[41]</a></span><span class='pagenum'><a name="Page_40" id="Page_40"></a></span>
+again travels on its down stroke the inlet valve opens and
+admits a charge of fresh gas and the cycle of operations
+is repeated.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig007" id="Fig007"></a>
+<img src="images/illo035.png" alt="Fig. 7" width="354" height="550" />
+<p class="caption">Fig. 7.&mdash;Sectional View of L Head Gasoline Engine Cylinder Showing
+Piston Movements During Four-Stroke Cycle.</p></div>
+
+<p>The illustrations at <a href="#Fig007">Fig. 7</a> show how the various cycle
+functions take place in an L head type water cooled cylinder
+engine. The sections at A and C are taken through
+the inlet valve, those at B and D are taken through the
+exhaust valve.</p>
+
+<p><a name="SecII_3" id="SecII_3"></a>The two-cycle engine works on a different principle, as
+while only the combustion chamber end of the piston is
+employed to do useful work in the four-cycle engine, both
+upper and lower portions are called upon to perform the
+functions necessary to two-cycle engine operation. Instead
+of the gas being admitted into the cylinder as is the
+case with the four-stroke engine, it is first drawn into the
+engine base where it receives a preliminary compression
+prior to its transfer to the working end of the cylinder.
+The views at <a href="#Fig008">Fig. 8</a> should indicate clearly the operation
+of the two-port two-cycle engine. At A the piston is
+seen reaching the top of its stroke and the gas above the
+piston is being compressed ready for ignition, while the
+suction in the engine base causes the automatic valve to
+open and admits mixture from the carburetor to the
+crank case. When the piston reaches the top of its stroke,
+the compressed gas is ignited and the piston is driven
+down on the power stroke, compressing the gas in the
+engine base.</p>
+
+<div class="figcenter" style="width: 750px;"><a name="Fig008" id="Fig008"></a>
+<img src="images/illo037.png" alt="Fig. 8" width="750" height="465" />
+<p class="caption">Fig. 8.&mdash;Showing Two-port, Two-cycle Engine Operation.</p></div>
+
+<p>When the top of the piston uncovers the exhaust port
+the flaming gas escapes because of its pressure. A downward
+movement of the piston uncovers the inlet port
+opposite the exhaust and permits the fresh gas to bypass
+through the transfer passage from the engine base to the
+cylinder. The conditions with the intake and exhaust
+port fully opened are clearly shown at <a href="#Fig008">Fig. 8</a>, C. The
+deflector plate on the top of the piston directs the entering
+fresh gas to the top of the cylinder and prevents the
+main portion of the gas stream from flowing out through
+the open exhaust port. On the next upstroke of the piston<span class='pagenum'><a
+name="Page_44" id="Page_44">[44]</a></span><span class='pagenum'><a name="Page_43"
+id="Page_43"></a></span><span class='pagenum'><a name="Page_42" id="Page_42"></a></span>
+the gas in the cylinder is compressed and the inlet valve
+opened, as shown at A to permit a fresh charge to enter
+the engine base.</p>
+
+<div class="figcenter" style="width: 750px;"><a name="Fig009" id="Fig009"></a>
+<img src="images/illo038.png" alt="Fig. 9" width="750" height="464" />
+<p class="caption">Fig. 9.&mdash;Defining Three-port, Two-cycle Engine Action.</p></div>
+
+<p>The operating principle of the three-port, two-cycle
+engine is practically the same as that previously described
+with the exception that the gas is admitted to the crank-case
+through a third port in the cylinder wall, which is
+uncovered by the piston when that member reaches the
+end of its upstroke. The action of the three-port form
+can be readily ascertained by studying the diagrams given
+at <a href="#Fig009">Fig. 9</a>. Combination two- and three-port engines have
+been evolved and other modifications made to improve the
+action.</p>
+
+<h3><a name="SecII_4" id="SecII_4"></a>THE TWO-CYCLE AND FOUR-CYCLE TYPES</h3>
+
+<p>In the earlier years of explosive-motor progress was
+evolved the two types of motors in regard to the cycles
+of their operation. The early attempts to perfect the
+two-cycle principle were for many years held in abeyance
+from the pressure of interests in the four-cycle type, until
+its simplicity and power possibilities were demonstrated
+by Mr. Dugald Clerk in England, who gave the principles
+of the two-cycle motor a broad bearing leading to immediate
+improvements in design, which has made further
+progress in the United States, until at the present time
+it has an equal standard value as a motor-power in some
+applications as its ancient rival the four-cycle or Otto
+type, as demonstrated by Beau de Rocha in 1862.</p>
+
+<p>Thermodynamically, the methods of the two types are
+equal as far as combustion is concerned, and compression
+may favor in a small degree the four-cycle type as well
+as the purity of the charge. The cylinder volume of the
+two-cycle motor is much smaller per unit of power, and
+the enveloping cylinder surface is therefore greater per
+unit of volume. Hence more heat is carried off by the
+jacket water during compression, and the higher compression
+available from this tends to increase the economy
+during compression which is lost during expansion.</p>
+
+<p><span class='pagenum'><a name="Page_45" id="Page_45">[45]</a></span>From the above considerations it may be safely stated
+that a <i>lower</i> temperature and higher pressure of charge
+at the beginning of compression is obtained in the two-cycle
+motor, greater weight of charge and greater specific
+power of higher compression resulting in higher thermal
+efficiency. The smaller cylinder for the same power of
+the two-cycle motor gives less friction surface per impulse
+than of the other type; although the crank-chamber pressure
+may, in a measure, balance the friction of the four-cycle
+type. Probably the strongest points in favor of the
+two-cycle type are the lighter fly-wheel and the absence
+of valves and valve gear, making this type the most simple
+in construction and the lightest in weight for its developed
+power. Yet, for the larger power units, the four-cycle
+type will no doubt always maintain the standard for
+efficiency and durability of action.</p>
+
+<p>The distribution of the charge and its degree of mixture
+with the remains of the previous explosion in the
+clearance space, has been a matter of discussion for both
+types of explosive motors, with doubtful results. In <a href="#Fig010">Fig.
+10</a>, A we illustrate what theory suggests as to the distribution
+of the fresh charge in a two-cycle motor, and in <a href="#Fig010">Fig.
+10</a>, B what is the probable distribution of the mixture when
+the piston starts on its compressive stroke. The arrows
+show the probable direction of flow of the fresh charge
+and burnt gases at the crucial moment.</p>
+
+<p>In <a href="#Fig010">Fig. 10</a>, C is shown the complete out-sweep of the
+products of combustion for the full extent of the piston
+stroke of a four-cycle motor, leaving only the volume of
+the clearance to mix with the new charge and at D the
+manner by which the new charge sweeps by the ignition
+device, keeping it cool and avoiding possibilities of pre-ignition
+by undue heating of the terminals of the sparking
+device. Thus, by enveloping the sparking device with
+the pure mixture, ignition spreads through the charge with
+its greatest possible velocity, a most desirable condition
+in high-speed motors with side-valve chambers and igniters
+within the valve chamber.</p>
+
+<p class='pagenum'><a name="Page_46" id="Page_46">[46]</a></p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig010" id="Fig010"></a>
+<img src="images/illo041.png" alt="Fig. 10" width="500" height="741" />
+<p class="caption">Fig. 10.&mdash;Diagrams Contrasting Action of Two- and Four-Cycle Cylinders
+on Exhaust and Intake Stroke.</p></div>
+
+<p class='pagenum'><a name="Page_47" id="Page_47">[47]</a></p>
+
+<h3><a name="SecII_5" id="SecII_5"></a>THEORY OF THE GAS AND GASOLINE ENGINE</h3>
+
+<p>The laws controlling the elements that create a power
+by their expansion by heat due to combustion, when properly
+understood, become a matter of computation in
+regard to their value as an agent for generating power
+in the various kinds of explosive engines. The method
+of heating the elements of power in explosive engines
+greatly widens the limits of temperature as available in
+other types of heat-engines. It disposes of many of the
+practical troubles of hot-air, and even of steam-engines,
+in the simplicity and directness of application of the elements
+of power. In the explosive engine the difficulty
+of conveying heat for producing expansive effect by convection
+is displaced by the generation of the required heat
+within the expansive element and at the instant of its
+useful work. The low conductivity of heat to and from
+air has been the great obstacle in the practical development
+of the hot-air engine; while, on the contrary, it has
+become the source of economy and practicability in the
+development of the internal-combustion engine.</p>
+
+<p>The action of air, gas, and the vapors of gasoline and
+petroleum oil, whether singly or mixed, is affected by
+changes of temperature practically in nearly the same
+ratio; but when the elements that produce combustion are
+interchanged in confined spaces, there is a marked difference
+of effect. The oxygen of the air, the hydrogen and
+carbon of a gas, or vapor of gasoline or petroleum oil are
+the elements that by combustion produce heat to expand
+the nitrogen of the air and the watery vapor produced
+by the union of the oxygen in the air and the hydrogen in
+the gas, as well as also the monoxide and carbonic-acid
+gas that may be formed by the union of the carbon of
+gas or vapor with part of the oxygen of the air. The
+various mixtures as between air and gas, or air and vapor,
+with the proportion of the products of combustion left
+in the cylinder from a previous combustion, form the
+elements to be considered in estimating the amount of<span class='pagenum'><a name="Page_48" id="Page_48">[48]</a></span>
+pressure that may be obtained by their combustion and
+expansive force.</p>
+
+<h3><a name="SecII_6" id="SecII_6"></a>EARLY GAS ENGINE FORMS</h3>
+
+<p>The working process of the explosive motor may be
+divided into three principal types: 1. Motors with charges
+igniting at constant volume without compression, such as
+the Lenoir, Hugon, and other similar types now abandoned
+as wasteful in fuel and effect. 2. Motors with charges
+igniting at constant pressure with compression, in which
+a receiver is charged by a pump and the gases burned
+while being admitted to the motor cylinder, such as types
+of the Simon and Brayton engine. 3. Motors with charges
+igniting at constant volume with variable compression,
+such as the later two- and four-cycle motors with compression
+of the indrawn charge; limited in the two-cycle type
+and variable in the four-cycle type with the ratios of the
+clearance space in the cylinder. This principle produces
+the explosive motor of greatest efficiency.</p>
+
+<p>The phenomena of the brilliant light and its accompanying
+heat at the moment of explosion have been witnessed
+in the experiments of Dugald Clerk in England,
+the illumination lasting throughout the stroke; but in
+regard to time in a four-cycle engine, the incandescent
+state exists only one-quarter of the running time. Thus
+the time interval, together with the non-conductibility of
+the gases, makes the phenomena of a high-temperature
+combustion within the comparatively cool walls of a cylinder
+a practical possibility.</p>
+
+<h3><a name="SecII_7" id="SecII_7"></a>THE ISOTHERMAL LAW</h3>
+
+<p>The natural laws, long since promulgated by Boyle,
+Gay Lussac, and others, on the subject of the expansion
+and compression of gases by force and by heat, and their
+variable pressures and temperatures when confined, are
+conceded to be practically true and applicable to all gases,
+whether single, mixed, or combined.</p>
+
+<p><span class='pagenum'><a name="Page_49" id="Page_49">[49]</a></span>The law formulated by Boyle only relates to the compression
+and expansion of gases without a change of
+temperature, and is stated in these words:</p>
+
+<p><i>If the temperature of a gas be kept constant, its pressure
+or elastic force will vary inversely as the volume
+it occupies.</i></p>
+
+<p>It is expressed in the formula P &times; V = C, or pressure
+&times; volume = constant. Hence, C/P = V and C/V = P.</p>
+
+<p>Thus the curve formed by increments of pressure during
+the expansion or compression of a given volume of
+gas without change of temperature is designated as the
+isothermal curve in which the volume multiplied by the
+pressure is a constant value in expansion, and inversely
+the pressure divided by the volume is a constant value
+in compressing a gas.</p>
+
+<p>But as compression and expansion of gases require
+force for their accomplishment mechanically, or by the
+application or abstraction of heat chemically, or by convection,
+a second condition becomes involved, which was
+formulated into a law of thermodynamics by Gay Lussac
+under the following conditions: A given volume of gas
+under a free piston expands by heat and contracts by the
+loss of heat, its volume causing a proportional movement
+of a free piston equal to <sup>1</sup>&#8260;<sub>273</sub> part of the cylinder volume
+for each degree Centigrade difference in temperature, or
+<sup>1</sup>&#8260;<sub>492</sub> part of its volume for each degree Fahrenheit. With
+a fixed piston (constant volume), the pressure is increased
+or decreased by an increase or decrease of heat in the
+same proportion of <sup>1</sup>&#8260;<sub>273</sub> part of its pressure for each
+degree Centigrade, or <sup>1</sup>&#8260;<sub>492</sub> part of its pressure for each
+degree Fahrenheit change in temperature. This is the
+natural sequence of the law of mechanical equivalent,
+which is a necessary deduction from the principle that<span class='pagenum'><a name="Page_50" id="Page_50">[50]</a></span>
+nothing in nature can be lost or wasted, for all the heat
+that is imparted to or abstracted from a gaseous body
+must be accounted for, either as heat or its equivalent
+transformed into some other form of energy. In the case
+of a piston moving in a cylinder by the expansive force
+of heat in a gaseous body, all the heat expended in expansion
+of the gas is turned into work; the balance must
+be accounted for in absorption by the cylinder or radiation.</p>
+
+<h3><a name="SecII_8" id="SecII_8"></a>THE ADIABATIC LAW</h3>
+
+<p>This theory is equally applicable to the cooling of gases
+by abstraction of heat or by cooling due to expansion by
+the motion of a piston. The denominators of these heat
+fractions of expansion or contraction represent the absolute
+zero of cold below the freezing-point of water, and
+read <span class="nowrap">-273&deg;</span> C. or <span class="nowrap">-492.66&deg;</span> =
+<span class="nowrap">-460.66&deg;</span> F. below zero;
+and these are the starting-points of reference in computing
+the heat expansion in gas-engines. According to
+Boyle&#8217;s law, called the first law of gases, there are but
+two characteristics of a gas and their variations to be
+considered, <i>viz</i>., volume and pressure: while by the law
+of Gay Lussac, called the second law of gases, a third
+is added, consisting of the value of the absolute temperature,
+counting from absolute zero to the temperatures
+at which the operations take place. This is the <i>Adiabatic</i>
+law.</p>
+
+<p>The ratio of the variation of the three conditions&mdash;volume,
+pressure, and heat&mdash;from the absolute zero temperature
+has a certain rate, in which the volume multiplied
+by the pressure and the product divided by the
+absolute temperature equals the ratio of expansion for
+each degree. If a volume of air is contained in a cylinder
+having a piston and fitted with an indicator, the piston,
+if moved to and fro slowly, will alternately compress and
+expand the air, and the indicator pencil will trace a line
+or lines upon the card, which lines register the change
+of pressure and volume occurring in the cylinder. If the
+piston is perfectly free from leakage, and it be supposed<span class='pagenum'><a name="Page_51" id="Page_51">[51]</a></span>
+that the temperature of the air is kept quite constant,
+then the line so traced is called an <i>Isothermal line</i>, and
+the pressure at any point when multiplied by the volume
+is a constant, according to Boyle&#8217;s law,</p>
+
+<p class="ind5"><i>pv</i> = a constant.</p>
+
+<p>If, however, the piston is moved very rapidly, the air will
+not remain at constant temperature, but the temperature
+will increase because work has been done upon the air,
+and the heat has no time to escape by conduction. If no
+heat whatever is lost by any cause, the line will be traced
+over and over again by the indicator pencil, the cooling
+by expansion doing work precisely equalling the heating
+by compression. This is the line of no transmission of
+heat, therefore known as <i>Adiabatic</i>.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig011" id="Fig011"></a>
+<img src="images/illo046.png" alt="Fig. 11" width="500" height="392" />
+<p class="caption">Fig. 11.&mdash;Diagram Isothermal and Adiabatic Lines.</p></div>
+
+<p>The expansion of a gas <sup>1</sup>&#8260;<sub>273</sub> of its volume for every
+degree Centigrade, added to its temperature, is equal to
+the decimal .00366, the coefficient of expansion for Centigrade
+units. To any given volume of a gas, its expansion
+may be computed by multiplying the coefficient by the<span class='pagenum'><a name="Page_52" id="Page_52">[52]</a></span>
+number of degrees, and by reversing the process the degree
+of acquired heat may be obtained approximately. These
+methods are not strictly in conformity with the absolute
+mathematical formula, because there is a small increase
+in the increment of expansion of a dry gas, and there is
+also a slight difference in the increment of expansion due
+to moisture in the atmosphere and to the vapor of water
+formed by the union of the hydrogen and oxygen in the
+combustion chamber of explosive engines.</p>
+
+<h3><a name="SecII_9" id="SecII_9"></a>TEMPERATURE COMPUTATIONS</h3>
+
+<p>The ratio of expansion on the Fahrenheit scale is derived
+from the absolute temperature below the freezing-point
+of water <span class="nowrap">(32&deg;)</span> to correspond with the Centigrade
+scale; therefore <sup>1</sup>&#8260;<sub>492.66</sub> = .0020297, the ratio of expansion
+from <span class="nowrap">32&deg;</span> for each degree rise in temperature on the Fahrenheit
+scale. As an example, if the temperature of any
+volume of air or gas at constant volume is raised, say
+from <span class="nowrap">60&deg;</span> to <span class="nowrap">2000&deg;</span> F., the increase in temperature will be
+<span class="nowrap">1940&deg;.</span> The ratio will be <sup>1</sup>&#8260;<sub>520.66</sub> = .0019206. Then by the
+formula:</p>
+
+<p>Ratio &times; acquired temp. &times; initial pressure = the gauge
+pressure; and .0019206 &times; <span class="nowrap">1940&deg;</span> &times; 14.7 = 54.77 lbs.</p>
+
+<p>By another formula, a convenient ratio is obtained by
+(absolute pressure)/(absolute temp.) or <sup>14.7</sup>&#8260;<sub>520.66</sub> = .028233; then, using the difference
+of temperature as before, .028233 &times; <span class="nowrap">1940&deg;</span> = 54.77
+lbs. pressure.</p>
+
+<p>By another formula, leaving out a small increment due
+to specific heat at high temperatures:</p>
+
+<p class='pagenum'><a name="Page_53" id="Page_53">[53]</a></p>
+
+<table class="formula" summary="formula p 53-1">
+
+<tr>
+<td rowspan="2" class="left">I.&nbsp;</td>
+<td class="center bb">Atmospheric pressure &times; absolute temp. + acquired temp.</td>
+<td rowspan="2" class="left">&nbsp;=&nbsp;</td>
+</tr>
+
+<tr>
+<td class="center">Absolute temp. + initial temp.</td>
+</tr>
+
+</table>
+
+<p>absolute pressure due to the acquired temperature, from
+which the atmospheric pressure is deducted for the
+gauge pressure. Using the foregoing example, we have</p>
+
+<table class="formula" summary="formula p 53-2">
+
+<tr>
+<td class="center bb">14.7 &times; <span class="nowrap">460.66&deg;</span> + <span class="nowrap">2000&deg;</span></td>
+<td rowspan="2" class="left">&nbsp;= 69.47 - 14.7 = 54.77, the gauge pressure,</td>
+</tr>
+
+<tr>
+<td class="center">460.66 + <span class="nowrap">60&deg;</span></td>
+</tr>
+
+</table>
+
+<p>460.66 being the absolute temperature for zero
+Fahrenheit.</p>
+
+<p>For obtaining the volume of expansion of a gas from
+a given increment of heat, we have the approximate
+formula:</p>
+
+<table class="formula" summary="formula p 53-3">
+
+<tr>
+<td rowspan="2" class="left">II.&nbsp;</td>
+<td class="center bb">Volume &times; absolute temp. + acquired temp.</td>
+<td rowspan="2" class="left">&nbsp;= heated volume.</td>
+</tr>
+
+<tr>
+<td class="center">Absolute temp. + initial temp.</td>
+</tr>
+
+</table>
+
+<p>In applying this formula to the foregoing example,
+the figures become:</p>
+
+<table class="formula" summary="formula p 53-4">
+
+<tr>
+<td rowspan="2" class="left">I. &times;</td>
+<td class="center bb"><span class="nowrap">460.66&deg;</span> + <span class="nowrap">2000&deg;</span></td>
+<td rowspan="2" class="left">&nbsp;= 4.72604 volumes.</td>
+</tr>
+
+<tr>
+<td class="center">460.66 + <span class="nowrap">60&deg;</span></td>
+</tr>
+
+</table>
+
+<p>From this last term the gauge pressure may be obtained
+as follows:</p>
+
+<p>III. 4.72604 &times; 14.7 = 69.47 lbs. absolute - 14.7 lbs. atmospheric
+pressure = 54.77 lbs. gauge pressure; which is
+the theoretical pressure due to heating air in a confined
+space, or at constant volume from <span class="nowrap">60&deg;</span> to <span class="nowrap">2000&deg;</span> F.</p>
+
+<p>By inversion of the heat formula for absolute pressure
+we have the formula for the acquired heat, derived from
+combustion at constant volume from atmospheric pressure
+to gauge pressure plus atmospheric pressure as derived
+from Example I., by which the expression</p>
+
+<table class="formula" summary="formula 53-5">
+
+<tr>
+<td class="center bb">absolute pressure &times; absolute temp. + initial temp.</td>
+</tr>
+
+<tr>
+<td class="center">initial absolute pressure</td>
+</tr>
+
+</table>
+
+<p><span class='pagenum'><a name="Page_54" id="Page_54">[54]</a></span>= absolute temperature + temperature of combustion,
+from which the acquired temperature is obtained by subtracting
+the absolute temperature.</p>
+
+<p>Then, for example,</p>
+
+<table class="formula" summary="formula p 54">
+
+<tr>
+<td class="center bb">69.47 &times; 460.66 + 60</td>
+<td rowspan="2" class="left">&nbsp;= 2460.66, and 2460.66 - 460.66 = <span class="nowrap">2000&deg;,</span></td>
+</tr>
+
+<tr>
+<td class="center">14.7</td>
+</tr>
+
+</table>
+
+<p>the theoretical heat of combustion.
+The dropping of terminal decimals makes a small
+decimal difference in the result in the different formulas.</p>
+
+<h3><a name="SecII_10" id="SecII_10"></a>HEAT AND ITS WORK</h3>
+
+<p>By Joule&#8217;s law of the mechanical equivalent of heat,
+whenever heat is imparted to an elastic body, as air or
+gas, energy is generated and mechanical work produced
+by the expansion of the air or gas. When the heat is imparted
+by combustion within a cylinder containing a movable
+piston, the mechanical work becomes an amount
+measurable by the observed pressure and movement of
+the piston. The heat generated by the explosive elements
+and the expansion of the non-combining elements of nitrogen
+and water vapor that may have been injected into the
+cylinder as moisture in the air, and the water vapor
+formed by the union of the oxygen of the air with the
+hydrogen of the gas, all add to the energy of the work
+from their expansion by the heat of internal combustion.
+As against this, the absorption of heat by the walls of the
+cylinder, the piston, and cylinder-head or clearance walls,
+becomes a modifying condition in the force imparted to
+the moving piston.</p>
+
+<p>It is found that when any explosive mixture of air and
+gas or hydrocarbon vapor is fired, the pressure falls far
+short of the pressure computed from the theoretical effect
+of the heat produced, and from gauging the expansion of
+the contents of a cylinder. It is now well known that in
+practice the high efficiency which is promised by theoretical
+calculation is never realized; but it must always be<span class='pagenum'><a name="Page_55" id="Page_55">[55]</a></span>
+remembered that the heat of combustion is the real agent,
+and that the gases and vapors are but the medium for the
+conversion of inert elements of power into the activity of
+energy by their chemical union. The theory of combustion
+has been the leading stimulus to large expectations with
+inventors and constructors of explosive motors; its entanglement
+with the modifying elements in practice has
+delayed the best development in construction, and as yet
+no really positive design of best form or action seems to
+have been accomplished, although great progress has been
+made during the past decade in the development of speed,
+reliability, economy, and power output of the individual
+units of this comparatively new power.</p>
+
+<p>One of the most serious difficulties in the practical development
+of pressure, due to the theoretical computations
+of the pressure value of the full heat, is probably caused
+by imparting the heat of the fresh charge to the balance
+of the previous charge that has been cooled by expansion
+from the maximum pressure to near the atmospheric
+pressure of the exhaust. The retardation in the velocity
+of combustion of perfectly mixed elements is now well
+known from experimental trials with measured quantities;
+but the principal difficulty in applying these conditions
+to the practical work of an explosive engine where a necessity
+for a large clearance space cannot be obviated,
+is in the inability to obtain a maximum effect from the
+imperfect mixture and the mingling of the products of
+the last explosion with the new mixture, which produces
+a clouded condition that makes the ignition of the mass
+irregular or chattering, as observed in the expansion lines
+of indicator cards; but this must not be confounded with
+the reaction of the spring in the indicator.</p>
+
+<p>Stratification of the mixture has been claimed as taking
+place in the clearance chamber of the cylinder; but this
+is not a satisfactory explanation in view of the vortical
+effect of the violent injection of the air and gas or vapor
+mixture. It certainly cannot become a perfect mixture
+in the time of a stroke of a high-speed motor of the two-cycle<span class='pagenum'><a name="Page_56" id="Page_56">[56]</a></span>
+class. In a four-cycle engine, making 1,500 revolutions
+per minute, the injection and compression in any
+one cylinder take place in one twenty-fifth of a second&mdash;formerly
+considered far too short a time for a perfect
+infusion of the elements of combustion but now very easily
+taken care of despite the extremely high speed of numerous
+aviation and automobile power-plants.</p>
+
+<h5><span class="smcap">Table I.&mdash;Explosion at Constant Volume in a Closed Chamber.</span></h5>
+
+<table class="fsize80" summary="table p 56">
+
+<tr class="bt2 bb">
+<td class="center padl1 padr1 br">Diagram<br />Curve<br />Fig. 8.</td>
+<td colspan="7" class="center padl1 padr1 br">Mixture Injected.</td>
+<td class="center padl1 padr1 br">Temp. of<br />Injection<br />Fahr.</td>
+<td colspan="2" class="center padl1 padr1 br">Time of<br />Explosion.<br />Second.</td>
+<td colspan="2" class="center padl1 padr1 br">Observed<br />Gauge<br />Pressure.<br />Pounds.</td>
+<td class="center padl1 padr1">Computed<br />Temp.<br />Fahr.</td>
+</tr>
+
+<tr>
+<td class="center br"><i>a</i></td>
+<td class="right padl1">1</td>
+<td class="center">&nbsp;volume&nbsp;</td>
+<td class="center">gas</td>
+<td class="center">&nbsp;to&nbsp;</td>
+<td class="right">14</td>
+<td class="center">&nbsp;volumes&nbsp;</td>
+<td class="center br">air.&nbsp;</td>
+<td class="right padr3 br">64&deg;</td>
+<td class="right padr0">0.45</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">40.</td>
+<td class="br">&nbsp;</td>
+<td class="right padr2">1,483&deg;</td>
+</tr>
+
+<tr>
+<td class="center br"><i>b</i></td>
+<td class="right padl1">1</td>
+<td class="center">&#8222;</td>
+<td class="center">&#8222;</td>
+<td class="center">&#8222;</td>
+<td class="right">13</td>
+<td class="center">&#8222;</td>
+<td class="center br">&#8222;</td>
+<td class="right padr3 br">51&deg;</td>
+<td class="right padr0">0.31</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">51.</td>
+<td class="left padl0 padr1 br">5</td>
+<td class="right padr2">1,859&deg;</td>
+</tr>
+
+<tr>
+<td class="center br"><i>c</i></td>
+<td class="right padl1">1</td>
+<td class="center">&#8222;</td>
+<td class="center">&#8222;</td>
+<td class="center">&#8222;</td>
+<td class="right">12</td>
+<td class="center">&#8222;</td>
+<td class="center br">&#8222;</td>
+<td class="right padr3 br">51&deg;</td>
+<td class="right padr0">0.24</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">60.</td>
+<td class="br">&nbsp;</td>
+<td class="right padr2">2,195&deg;</td>
+</tr>
+
+<tr>
+<td class="center br"><i>d</i></td>
+<td class="right padl1">1</td>
+<td class="center">&#8222;</td>
+<td class="center">&#8222;</td>
+<td class="center">&#8222;</td>
+<td class="right">11</td>
+<td class="center">&#8222;</td>
+<td class="center br">&#8222;</td>
+<td class="right padr3 br">51&deg;</td>
+<td class="right padr0">0.17</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">61.</td>
+<td class="br">&nbsp;</td>
+<td class="right padr2">2,228&deg;</td>
+</tr>
+
+<tr>
+<td class="center br"><i>e</i></td>
+<td class="right padl1">1</td>
+<td class="center">&#8222;</td>
+<td class="center">&#8222;</td>
+<td class="center">&#8222;</td>
+<td class="right">9</td>
+<td class="center">&#8222;</td>
+<td class="center br">&#8222;</td>
+<td class="right padr3 br">62&deg;</td>
+<td class="right padr0">0.08</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">78.</td>
+<td class="br">&nbsp;</td>
+<td class="right padr2">2,835&deg;</td>
+</tr>
+
+<tr>
+<td class="center br"><i>f</i></td>
+<td class="right padl1">1</td>
+<td class="center">&#8222;</td>
+<td class="center">&#8222;</td>
+<td class="center">&#8222;</td>
+<td class="right">7</td>
+<td class="center">&#8222;</td>
+<td class="center br">&#8222;</td>
+<td class="right padr3 br">62&deg;</td>
+<td class="right padr0">0.06</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">87.</td>
+<td class="br">&nbsp;</td>
+<td class="right padr2">3,151&deg;</td>
+</tr>
+
+<tr>
+<td class="center br"><i>g</i></td>
+<td class="right padl1">1</td>
+<td class="center">&#8222;</td>
+<td class="center">&#8222;</td>
+<td class="center">&#8222;</td>
+<td class="right">6</td>
+<td class="center">&#8222;</td>
+<td class="center br">&#8222;</td>
+<td class="right padr3 br">51&deg;</td>
+<td class="right padr0">0.04</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">90.</td>
+<td class="br">&nbsp;</td>
+<td class="right padr2">3,257&deg;</td>
+</tr>
+
+<tr>
+<td class="center br"><i>h</i></td>
+<td class="right padl1">1</td>
+<td class="center">&#8222;</td>
+<td class="center">&#8222;</td>
+<td class="center">&#8222;</td>
+<td class="right">5</td>
+<td class="center">&#8222;</td>
+<td class="center br">&#8222;</td>
+<td class="right padr3 br">51&deg;</td>
+<td class="right padr0">0.05</td>
+<td class="left padl0 padr1 br">5</td>
+<td class="right padr0">91.</td>
+<td class="br">&nbsp;</td>
+<td class="right padr2">3,293&deg;</td>
+</tr>
+
+<tr class="bb">
+<td class="center br"><i>i</i></td>
+<td class="right padl1">1</td>
+<td class="center">&#8222;</td>
+<td class="center">&#8222;</td>
+<td class="center">&#8222;</td>
+<td class="right">4</td>
+<td class="center">&#8222;</td>
+<td class="center br">&#8222;</td>
+<td class="right padr3 br">66&deg;</td>
+<td class="right padr0">0.16</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">80.</td>
+<td class="br">&nbsp;</td>
+<td class="right padr2">2,871&deg;</td>
+</tr>
+
+</table>
+
+<p>In an examination of the times of explosion and the
+corresponding pressures in both tables, it will be seen that
+a mixture of 1 part gas to 6 parts air is the most effective
+and will give the highest mean pressure in a gas-engine.
+There is a limit to the relative proportions of illuminating
+gas and air mixture that is explosive, somewhat variable,
+depending upon the proportion of hydrogen in the gas.
+With ordinary coal-gas, 1 of gas to 15 parts of air; and
+on the lower end of the scale, 1 volume of gas to 2 parts
+air, are non-explosive. With gasoline vapor the explosive
+effect ceases at 1 to 16, and a saturated mixture of equal
+volumes of vapor and air will not explode, while the most
+intense explosive effect is from a mixture of 1 part vapor
+to 9 parts air. In the use of gasoline and air mixtures
+from a carburetor, the best effect is from 1 part saturated
+air to 8 parts free air.</p>
+
+<p class='pagenum'><a name="Page_57" id="Page_57">[57]</a></p>
+
+<h5><span class="smcap">Table II.&mdash;Properties and Explosive Temperature of a Mixture of
+One Part<br />of Illuminating Gas of 660 Thermal Units per Cubic Foot
+with Various<br />Proportions of Air without Mixture of Charge with
+the Products of a<br />Previous Explosion.</span></h5>
+
+<table class="fsize80 nowrap" summary="table p 57">
+
+<tr class="bt2 bb">
+<td colspan="3" rowspan="2" class="center padl1 padr1 br">Propor-<br />tion,<br />Air to<br />Gas by<br />Volumes.</td>
+<td rowspan="2" class="center padl1 padr1 br">Pounds<br />in One<br />Cubic<br />Foot of<br />Mixture.</td>
+<td colspan="2" class="center padl1 padr1 br">Specific Heat.<br />Heat Units Required<br />to Raise 1 Lb. 1 Deg.<br />Fahrenheit.</td>
+<td rowspan="2" class="center padl1 padr1 br">Heat to<br />Raise One<br />Cubic Foot<br />of Mixture<br />1 Deg.<br />Fahr.</td>
+<td colspan="2" rowspan="2" class="center padl1 padr1 br">Heat Units<br />Evolved by<br />Combus-<br />tion.</td>
+<td colspan="2" rowspan="2" class="center padl1 padr1 br">Ratio<br />Col.<br />6/5</td>
+<td rowspan="2" class="center padl1 padr1 br">Usual<br />Combus-<br />tion<br />Efficien-<br />cy.</td>
+<td rowspan="2" class="center padl1 padr1">Usual<br />Rise of<br />Temperature<br />due to<br />Explosion<br />at<br />Constant<br />Volume.</td>
+</tr>
+
+<tr class="bb">
+<td class="center padl1 padr1 br">Constant<br />Pressure.</td>
+<td class="center padl1 padr1 br">Constant<br />Volume.</td>
+</tr>
+
+<tr>
+<td class="right">6</td>
+<td class="center">&nbsp;to&nbsp;</td>
+<td class="right padr2 br">1</td>
+<td class="center br">.074195</td>
+<td class="center br">.2668</td>
+<td class="center br">.1913</td>
+<td class="center br">.014189</td>
+<td class="right padr0">94.</td>
+<td class="left padl0 br">28</td>
+<td class="right padr0">6644.</td>
+<td class="left padl0 br">6</td>
+<td class="left padl3 br">.465</td>
+<td class="center">3090</td>
+</tr>
+
+<tr>
+<td class="right">7</td>
+<td class="center">&nbsp;to&nbsp;</td>
+<td class="right padr2 br">1</td>
+<td class="center br">.075012</td>
+<td class="center br">.2628</td>
+<td class="center br">.1882</td>
+<td class="center br">.014116</td>
+<td class="right padr0">82.</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">5844.</td>
+<td class="left padl0 br">4</td>
+<td class="left padl3 br">.518</td>
+<td class="center">3027</td>
+</tr>
+
+<tr>
+<td class="right">8</td>
+<td class="center">&nbsp;to&nbsp;</td>
+<td class="right padr2 br">1</td>
+<td class="center br">.075647</td>
+<td class="center br">.2598</td>
+<td class="center br">.1858</td>
+<td class="center br">.014059</td>
+<td class="right padr0">73.</td>
+<td class="left padl0 br">33</td>
+<td class="right padr0">5216.</td>
+<td class="left padl0 br">1</td>
+<td class="left padl3 br">.543</td>
+<td class="center">2832</td>
+</tr>
+
+<tr>
+<td class="right">9</td>
+<td class="center">&nbsp;to&nbsp;</td>
+<td class="right padr2 br">1</td>
+<td class="center br">.076155</td>
+<td class="center br">.2575</td>
+<td class="center br">.1846</td>
+<td class="center br">.014013</td>
+<td class="right padr0">66.</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">4709.</td>
+<td class="left padl0 br">9</td>
+<td class="left padl3 br">.56</td>
+<td class="center">2637</td>
+</tr>
+
+<tr>
+<td class="right">10</td>
+<td class="center">&nbsp;to&nbsp;</td>
+<td class="right padr2 br">1</td>
+<td class="center br">.076571</td>
+<td class="center br">.2555</td>
+<td class="center br">.1825</td>
+<td class="center br">.013976</td>
+<td class="right padr0">60.</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">4293.</td>
+<td class="br">&nbsp;</td>
+<td class="left padl3 br">.575</td>
+<td class="center">2468</td>
+</tr>
+
+<tr>
+<td class="right">11</td>
+<td class="center">&nbsp;to&nbsp;</td>
+<td class="right padr2 br">1</td>
+<td class="center br">.076917</td>
+<td class="center br">.2540</td>
+<td class="center br">.1813</td>
+<td class="center br">.013945</td>
+<td class="right padr0">55.</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">3944.</td>
+<td class="br">&nbsp;</td>
+<td class="left padl3 br">.585</td>
+<td class="center">2307</td>
+</tr>
+
+<tr class="bb">
+<td class="right">12</td>
+<td class="center">&nbsp;to&nbsp;</td>
+<td class="right padr2 br">1</td>
+<td class="center br">.077211</td>
+<td class="center br">.2526</td>
+<td class="center br">.1803</td>
+<td class="center br">.013922</td>
+<td class="right padr0">50.</td>
+<td class="left padl0 br">77</td>
+<td class="right padr0">3646.</td>
+<td class="left padl0 br">7</td>
+<td class="left padl3 br">.58</td>
+<td class="center">2115</td>
+</tr>
+
+</table>
+
+<p>The weight of a cubic foot of gas and air mixture as
+given in Col. 2 is found by adding the number of volumes
+of air multiplied by its weight, .0807, to one volume of gas
+of weight .035 pound per cubic foot and dividing by the
+total number of volumes; for example, as in the table,
+6 &times; .0807 = .<sup>5192</sup>&#8260;<sub>7</sub> = .074195 as in the first line, and so on
+for any mixture or for other gases of different specific
+weight per cubic foot. The heat units evolved by combustion
+of the mixture (Col. 6) are obtained by dividing
+the total heat units in a cubic foot of gas by the total
+proportion of the mixture, <sup>660</sup>&#8260;<sub>7</sub> = 94.28 as in the first line
+of the table. Col. 5 is obtained by multiplying the weight
+of a cubic foot of the mixture in Col. 2 by the specific heat
+at a constant volume (Col. 4), Col. 6/Col. 5 = Col. 7 the total
+heat<span class='pagenum'><a name="Page_58" id="Page_58">[58]</a></span>
+ratio, of which Col. 8 gives the usual combustion efficiency&mdash;Col.
+7 &times; Col. 8 gives the absolute rise in temperature
+of a pure mixture, as given in Col. 9.</p>
+
+<p>The many recorded experiments made to solve the discrepancy
+between the theoretical and the actual heat development
+and resulting pressures in the cylinder of an
+explosive motor, to which much discussion has been given
+as to the possibilities of dissociation and the increased
+specific heat of the elements of combustion and non-combustion,
+as well, also, of absorption and radiation of heat,
+have as yet furnished no satisfactory conclusion as to
+what really takes place within the cylinder walls. There
+seems to be very little known about dissociation, and
+somewhat vague theories have been advanced to explain
+the phenomenon. The fact is, nevertheless, apparent as
+shown in the production of water and other producer
+gases by the use of steam in contact with highly incandescent
+fuel. It is known that a maximum explosive
+mixture of pure gases, as hydrogen and oxygen or carbonic
+oxide and oxygen, suffers a contraction of one-third
+their volume by combustion to their compounds, steam or
+carbonic acid. In the explosive mixtures in the cylinder
+of a motor, however, the combining elements form so
+small a proportion of the contents of the cylinder that
+the shrinkage of their volume amounts to no more than
+3 per cent. of the cylinder volume. This by no means
+accounts for the great heat and pressure differences between
+the theoretical and actual effects.</p>
+
+<h3><a name="SecII_11" id="SecII_11"></a>CONVERSION OF HEAT TO POWER</h3>
+
+<p>The utilization of heat in any heat-engine has long
+been a theme of inquiry and experiment with scientists
+and engineers, for the purpose of obtaining the best practical
+conditions and construction of heat-engines that would
+represent the highest efficiency or the nearest approach
+to the theoretical value of heat, as measured by empirical
+laws that have been derived from experimental researches
+relating to its ultimate volume. It is well known that the<span class='pagenum'><a name="Page_59" id="Page_59">[59]</a></span>
+steam-engine returns only from 12 to 18 per cent. of the
+power due to the heat generated by the fuel, about 25
+per cent. of the total heat being lost in the chimney, the
+only use of which is to create a draught for the fire; the
+balance, some 60 per cent., is lost in the exhaust and by
+radiation. The problem of utmost utilization of force
+in steam has nearly reached its limit.</p>
+
+<p>The internal-combustion system of creating power is
+comparatively new in practice, and is but just settling
+into definite shape by repeated trials and modification of
+details, so as to give somewhat reliable data as to what
+may be expected from the rival of the steam-engine as
+a prime mover. For small powers, the gas, gasoline, and
+petroleum-oil engines are forging ahead at a rapid rate,
+filling the thousand wants of manufacture and business
+for a power that does not require expensive care, that
+is perfectly safe at all times, that can be used in any place
+in the wide world to which its concentrated fuel can be
+conveyed, and that has eliminated the constant handling
+of crude fuel and water.</p>
+
+<h3><a name="SecII_12" id="SecII_12"></a>REQUISITES FOR BEST POWER EFFECT</h3>
+
+<p>The utilization of heat in a gas-engine is mainly due
+to the manner in which the products entering into combustion
+are distributed in relation to the movement of
+the piston. The investigation of the foremost exponent
+of the theory of the explosive motor was prophetic in
+consideration of the later realization of the best conditions
+under which these motors can be made to meet the
+requirements of economy and practicability. As early as
+1862, Beau de Rocha announced, in regard to the coming
+power, that four requisites were the basis of operation
+for economy and best effect. 1. The greatest possible
+cylinder volume with the least possible cooling surface.
+2. The greatest possible rapidity of expansion. Hence,
+<i>high speed</i>. 3. The greatest possible expansion. <i>Long
+stroke.</i> 4. The greatest possible pressure at the commencement
+of expansion. <i>High compression</i>.</p>
+
+<hr class="c25" />
+<p class='pagenum'><a name="Page_60" id="Page_60">[60]</a></p>
+<h2><a name="ChIII" id="ChIII"></a>CHAPTER III</h2>
+
+<div class="chapsec"><p><a href="#SecIII_1">Efficiency of Internal Combustion Engines</a>&mdash;<a href="#SecIII_2">Various
+Measures of Efficiency</a>&mdash;<a href="#SecIII_3">Temperatures
+and Pressures</a>&mdash;<a href="#SecIII_4">Factors Governing Economy</a>&mdash;<a href="#SecIII_5">Losses
+in Wall Cooling</a>&mdash;<a href="#SecIII_6">Value of Indicator Cards</a>&mdash;<a href="#SecIII_7">Compression
+in Explosive Motors</a>&mdash;<a href="#SecIII_8">Factors Limiting Compression</a>&mdash;<a href="#SecIII_9">Causes
+of Heat Losses and Inefficiency</a>&mdash;<a href="#SecIII_10">Heat Losses to Cooling Water</a>.</p></div>
+
+<h3><a name="SecIII_1" id="SecIII_1"></a>EFFICIENCY OF INTERNAL COMBUSTION ENGINES</h3>
+
+<p>Efficiencies are worked out through intricate formulas
+for a variety of theoretical and unknown conditions of
+combustion in the cylinder: ratios of clearance and cylinder
+volume, and the uncertain condition of the products
+of combustion left from the last impulse and the wall
+temperature. But they are of but little value, except as
+a mathematical inquiry as to possibilities. The real commercial
+efficiency of a gas or gasoline-engine depends upon
+the volume of gas or liquid at some assigned cost, required
+per actual brake horse-power per hour, in which
+an indicator card should show that the mechanical action
+of the valve gear and ignition was as perfect as practicable,
+and that the ratio of clearance, space, and cylinder
+volume gave a satisfactory terminal pressure and compression:
+<i>i.e.</i>, the difference between the power figured
+from the indicator card and the brake power being the
+friction loss of the engine.</p>
+
+<p>In four-cycle motors of the compression type, the efficiencies
+are greatly advanced by compression, producing
+a more complete infusion of the mixture of gas or vapor
+and air, quicker firing, and far greater pressure than is
+possible with the two-cycle type previously described. In
+the practical operation of the gas-engine during the past
+twenty years, the gas-consumption efficiencies per indicated
+horse-power have gradually risen from 17 per cent.
+to a maximum of 40 per cent. of the theoretical heat, and<span class='pagenum'><a name="Page_61" id="Page_61">[61]</a></span>
+this has been done chiefly through a decreased combustion
+chamber and increased compression&mdash;the compression having
+gradually increased in practice from 30 lbs. per square
+inch to above 100; but there seems to be a limit to compression,
+as the efficiency ratio decreases with greater increase
+in compression. It has been shown that an ideal
+efficiency of 33 per cent. for 38 lbs., compression will increase
+to 40 per cent. for 66 lbs., and 43 per cent. for 88
+lbs. compression. On the other hand, greater compression
+means greater explosive pressure and greater strain on
+the engine structure, which will probably retain in future
+practice the compression between the limits of 40 and 90
+lbs. except in super-compression engines intended for
+high altitude work where compression pressures as high
+as 125 pounds have been used.</p>
+
+<p>In experiments made by Dugald Clerk, in England,
+with a combustion chamber equal to 0.6 of the space swept
+by the piston, with a compression of 38 lbs., the consumption
+of gas was 24 cubic feet per indicated horse-power
+per hour. With 0.4 compression space and 61 lbs. compression,
+the consumption of gas was 20 cubic feet per
+indicated horse-power per hour; and with 0.34 compression
+space and 87 lbs. compression, the consumption of
+gas fell to 14.8 cubic feet per indicated horse-power per
+hour&mdash;the actual efficiencies being respectively 17, 21, and
+25 per cent. This was with a Crossley four-cycle engine.</p>
+
+<h3><a name="SecIII_2" id="SecIII_2"></a>VARIOUS MEASURES OF EFFICIENCY</h3>
+
+<p>The efficiencies in regard to power in a heat-engine
+may be divided into four kinds, as follows: I. The first
+is known as the <i>maximum theoretical efficiency</i> of a perfect
+engine (represented by the lines in the indicator diagram).
+It is expressed by the formula</p>
+
+<table class="formula" summary="formula p 61">
+
+<tr>
+<td class="center bb">T<sub>1</sub> - T<sub>0</sub></td>
+</tr>
+
+<tr>
+<td class="center">T<sub>1</sub> </td>
+</tr>
+
+</table>
+
+<p>and shows
+the work of a perfect cycle in an engine working between
+the received temperature + absolute temperature (T<sub>1</sub>) and<span class='pagenum'><a name="Page_62" id="Page_62">[62]</a></span>
+the initial atmospheric temperature + absolute temperature
+(T<sub>0</sub>). II. The second is the <i>actual heat efficiency</i>,
+or the ratio of the heat turned into work to the total heat
+received by the engine. It expresses the <i>indicated horse-power</i>.
+III. The third is the ratio between the second
+or <i>actual heat efficiency</i> and the first or <i>maximum theoretical
+efficiency</i> of a perfect cycle. It represents the
+greatest possible utilization of the power of heat in an
+internal-combustion engine. IV. The fourth is the <i>mechanical
+efficiency</i>. This is the ratio between the actual
+horse-power delivered by the engine through a dynamometer
+or measured by a brake (brake horse-power),
+and the indicated horse-power. The difference between
+the two is the power lost by engine friction. In regard
+to the general heat efficiency of the materials of power
+in explosive engines, we find that with good illuminating
+gas the practical efficiency varies from 25 to 40 per cent.;
+kerosene-motors, 20 to 30; gasoline-motors, 20 to 32; acetylene,
+25 to 35; alcohol, 20 to 30 per cent. of their heat
+value. The great variation is no doubt due to imperfect
+mixtures and variable conditions of the old and new charge
+in the cylinder; uncertainty as to leakage and the perfection<span class='pagenum'><a name="Page_63" id="Page_63">[63]</a></span>
+of combustion. In the Diesel motors operating under
+high pressure, up to nearly 500 pounds, an efficiency of
+36 per cent. is claimed.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig012" id="Fig012"></a>
+<img src="images/illo057.png" alt="Fig. 12" width="500" height="255" />
+<p class="caption">Fig. 12.&mdash;Graphic Diagram Showing Approximate Utilization of Fuel
+Burned in Internal-Combustion Engine.</p></div>
+
+<p>The graphic diagram at <a href="#Fig012">Fig. 12</a> is of special value as
+it shows clearly how the heat produced by charge combustion
+is expended in an engine of average design.</p>
+
+<p>On general principles the greater difference between
+the heat of combustion and the heat at exhaust is the
+relative measure of the heat turned into work, which
+represents the degree of efficiency without loss during
+expansion. The mathematical formulas appertaining to
+the computation of the element of heat and its work in
+an explosive engine are in a large measure dependent
+upon assumed values, as the conditions of the heat of
+combustion are made uncertain by the mixing of the fresh
+charge with the products of a previous combustion, and
+by absorption, radiation, and leakage. The computation
+of the temperature from the observed pressure may be
+made as before explained, but for compression-engines
+the needed starting-points for computation are very uncertain,
+and can only be approximated from the exact
+measure and value of the elements of combustion in a
+cylinder charge.</p>
+
+<h3><a name="SecIII_3" id="SecIII_3"></a>TEMPERATURES AND PRESSURES</h3>
+
+<p>Owing to the decrease from atmospheric pressure in
+the indrawing charge of the cylinder, caused by valve and
+frictional obstruction, the compression seldom starts above
+13 lbs. absolute, especially in high-speed engines. Col. 3
+in the following table represents the approximate absolute
+compression pressure for the clearance percentage and
+ratio in Cols. 1 and 2, while Col. 4 indicates the gauge
+pressure from the atmospheric line. The temperatures in
+Col. 5 are due to the compression in Col. 3 from an assumed
+temperature of <span class="nowrap">560&deg;</span> F. in the mixture of the fresh
+charge of 6 air to 1 gas with the products of combustion
+left in the clearance chamber from the exhaust stroke of
+a medium-speed motor. This temperature is subject to<span class='pagenum'><a name="Page_64" id="Page_64">[64]</a></span>
+considerable variation from the difference in the heat-unit
+power of the gases and vapors used for explosive
+power, as also of the cylinder-cooling effect. In Col. 6 is
+given the approximate temperatures of explosion for a
+mixture of air 6 to gas 1 of 660 heat units per cubic foot,
+for the relative values of the clearance ratio in Col. 2 at
+constant volume.</p>
+
+<h5><span class="smcap">Table III.&mdash;Gas-Engine Clearance Ratios, Approximate Compression,<br />
+Temperatures of Explosion and Explosive Pressures with a Mixture<br />
+of Gas of 660 Heat Units per Cubic Foot and Mixture of Gas<br />
+1 to 6 of Air.</span></h5>
+
+<table class="fsize80 nowrap" summary="table p 64">
+
+<tr class="bt2 bb">
+<td class="center padl1 padr1 br">Clearance<br />Per Cent.<br />of<br />Piston<br />Volume.</td>
+<td colspan="2" class="center padl1 padr1 br">Ratio<br />
+<table style="margin: 0 auto;" summary="formula part1 in table">
+  <tr>
+  <td class="center bb"><i>V</i></td>
+  <td rowspan="2" class="center">&nbsp;=&nbsp;</td>
+  </tr>
+  <tr>
+  <td class="center"><i>V<sub><b>c</b></sub></i></td>
+  </tr>
+</table><br />
+<table style="margin: 0 auto;" summary="formula part2 in table">
+  <tr>
+  <td class="center bb"><i>P</i> + <i>C</i> Vol.</td>
+  </tr>
+  <tr>
+  <td class="center">Clearance</td>
+  </tr>
+</table>
+</td>
+<td class="center padl1 padr1 br">Approximate<br />Compression<br />from<br />13 Pounds<br />Absolute.</td>
+<td class="center padl1 padr1 br">Approximate<br />Gauge<br />Pressure.</td>
+<td class="center padl1 padr1 br">Absolute<br />Temperature<br />of<br />Compression<br />from 560 Deg.<br />
+Fahrenheit<br />in Cylinder.</td>
+<td class="center padl1 padr1 br">Absolute<br />Temperature<br />of Explosion.<br />Gas, 1 part;<br />Air, 6 parts.</td>
+<td class="center padl1 padr1 br">Approximate<br />Explosion<br />Pressure<br />Absolute.</td>
+<td class="center padl1 padr1 br">Approximate<br />Gauge<br />Pressure.</td>
+<td class="center padl1 padr1">Approximate<br />Temperature<br />of<br />Explosion,<br />Fahrenheit.</td>
+</tr>
+
+<tr class="bb">
+<td class="center br">1</td>
+<td colspan="2" class="center br">2</td>
+<td class="center br">3</td>
+<td class="center br">4</td>
+<td class="center br">5</td>
+<td class="center br">6</td>
+<td class="center br">7</td>
+<td class="center br">8</td>
+<td class="center">9</td>
+</tr>
+
+<tr>
+<td class="br">&nbsp;</td>
+<td colspan="2" class="br">&nbsp;</td>
+<td class="center br">Lbs.</td>
+<td class="br">&nbsp;</td>
+<td class="center br">Deg.</td>
+<td class="center br">Deg.</td>
+<td class="center br">Lbs.</td>
+<td class="center br">Lbs.</td>
+<td class="center">Deg.</td>
+</tr>
+
+<tr>
+<td class="left padl3 br">.50</td>
+<td class="right padr0">3.</td>
+<td class="br">&nbsp;</td>
+<td class="right padr5 br">57.</td>
+<td class="center br">42.</td>
+<td class="center br">822.</td>
+<td class="center br">2488</td>
+<td class="center br">169</td>
+<td class="center br">144</td>
+<td class="center">2027</td>
+</tr>
+
+<tr>
+<td class="left padl3 br">.444</td>
+<td class="right padr0">3.</td>
+<td class="left padl0 br">25</td>
+<td class="right padr5 br">65.</td>
+<td class="center br">50.</td>
+<td class="center br">846.</td>
+<td class="center br">2568</td>
+<td class="center br">197</td>
+<td class="center br">182</td>
+<td class="center">2107</td>
+</tr>
+
+<tr>
+<td class="left padl3 br">.40</td>
+<td class="right padr0">3.</td>
+<td class="left padl0 br">50</td>
+<td class="right padr5 br">70.</td>
+<td class="center br">55.</td>
+<td class="center br">868.</td>
+<td class="center br">2638</td>
+<td class="center br">212</td>
+<td class="center br">197</td>
+<td class="center">2177</td>
+</tr>
+
+<tr>
+<td class="left padl3 br">.363</td>
+<td class="right padr0">3.</td>
+<td class="left padl0 br">75</td>
+<td class="right padr5 br">77.</td>
+<td class="center br">62.</td>
+<td class="center br">889.</td>
+<td class="center br">2701</td>
+<td class="center br">234</td>
+<td class="center br">219</td>
+<td class="center">2240</td>
+</tr>
+
+<tr>
+<td class="left padl3 br">.333</td>
+<td class="right padr0">4.</td>
+<td class="br">&nbsp;</td>
+<td class="right padr5 br">84.</td>
+<td class="center br">69.</td>
+<td class="center br">910.</td>
+<td class="center br">2751</td>
+<td class="center br">254</td>
+<td class="center br">239</td>
+<td class="center">2290</td>
+</tr>
+
+<tr>
+<td class="left padl3 br">.285</td>
+<td class="right padr0">4.</td>
+<td class="left padl0 br">50</td>
+<td class="right padr5 br">102.</td>
+<td class="center br">88.</td>
+<td class="center br">955.</td>
+<td class="center br">2842</td>
+<td class="center br">303</td>
+<td class="center br">288</td>
+<td class="center">2381</td>
+</tr>
+
+<tr class="bb">
+<td class="left padl3 br">.25</td>
+<td class="right padr0">5.</td>
+<td class="br">&nbsp;</td>
+<td class="right padr5 br">114.</td>
+<td class="center br">99.</td>
+<td class="center br">983.</td>
+<td class="center br">2901</td>
+<td class="center br">336</td>
+<td class="center br">321</td>
+<td class="center">2440</td>
+</tr>
+
+</table>
+
+<h3><a name="SecIII_4" id="SecIII_4"></a>FACTORS GOVERNING ECONOMY</h3>
+
+<p>In view of the experiments in this direction, it clearly
+shows that in practical work, to obtain the greatest economy
+per effective brake horse-power, it is necessary: 1st.
+To transform the heat into work with the greatest rapidity
+mechanically allowable. This means high piston speed.
+2d. To have high initial compression. 3d. To reduce the
+duration of contact between the hot gases and the cylinder
+walls to the smallest amount possible; which means short
+stroke and quick speed, with a spherical cylinder head.
+4th. To adjust the temperature of the jacket water to<span class='pagenum'><a name="Page_65" id="Page_65">[65]</a></span>
+obtain the most economical output of actual power. This
+means water-tanks or water-coils, with air-cooling surfaces
+suitable and adjustable to the most economical requirement
+of the engine, which by late trials requires the jacket water
+to be discharged at about <span class="nowrap">200&deg;</span> F. 5th. To reduce the
+wall surface of the clearance space or combustion chamber
+to the smallest possible area, in proportion to its required
+volume. This lessens the loss of the heat of combustion by
+exposure to a large surface, and allows of a higher mean
+wall temperature to facilitate the heat of compression.</p>
+
+<h3><a name="SecIII_5" id="SecIII_5"></a>LOSSES IN WALL COOLING</h3>
+
+<p>In an experimental investigation of the efficiency of a
+gas-engine under variable piston speeds made in France,
+it was found that the useful effect increases with the velocity
+of the piston&mdash;that is, with the rate of expansion
+of the burning gases with mixtures of uniform volumes:
+so that the variations of time of complete combustion
+at constant pressure, and the variations due to speed, in
+a way compensate in their efficiencies. The dilute mixture,
+being slow burning, will have its time and pressure
+quickened by increasing the speed.</p>
+
+<p>Careful trials give unmistakable evidence that the useful
+effect increases with the velocity of the piston&mdash;that
+is, with the rate of expansion of the burning gases. The
+time necessary for the explosion to become complete and
+to attain its maximum pressure depends not only on the
+composition of the mixture, but also upon the rate of expansion.
+This has been verified in experiments with a
+high-speed motor, at speeds from 500 to 2,000 revolutions
+per minute, or piston speeds of from 16 to 64 feet per
+second. The increased speed of combustion due to increased
+piston speed is a matter of great importance to
+builders of gas-engines, as well as to the users, as indicating
+the mechanical direction of improvements to lessen
+the wearing strain due to high speed and to lighten the
+vibrating parts with increased strength, in order that the<span class='pagenum'><a name="Page_66" id="Page_66">[66]</a></span>
+balancing of high-speed engines may be accomplished with
+the least weight.</p>
+
+<p>From many experiments made in Europe and in the
+United States, it has been conclusively proved that excessive
+cylinder cooling by the water-jacket results in a
+marked loss of efficiency. In a series of experiments with
+a simplex engine in France, it was found that a saving
+of 7 per cent. in gas consumption per brake horse-power
+was made by raising the temperature of the jacket water
+from <span class="nowrap">141&deg;</span> to <span class="nowrap">165&deg;</span> F. A still greater saving was made in
+a trial with an Otto engine by raising the temperature of
+the jacket water from <span class="nowrap">61&deg;</span> to <span class="nowrap">140&deg;</span> F.&mdash;it being 9.5 per
+cent. less gas per brake horse-power.</p>
+
+<p>It has been stated that volumes of similar cylinders
+increase as the cube of their diameters, while the surface
+of their cold walls varies as the square of their diameters;
+so that for large cylinders the ratio of surface to volume
+is less than for small ones. This points to greater economy
+in the larger engines. The study of many experiments
+goes to prove that combustion takes place gradually
+in the gas-engine cylinder, and that the rate of increase
+of pressure or rapidity of firing is controlled by dilution
+and compression of the mixture, as well as by the rate
+of expansion or piston speed. The rate of combustion
+also depends on the size and shape of the explosion chamber,
+and is increased by the mechanical agitation of the
+mixture during combustion, and still more by the mode
+of firing.</p>
+
+<h3><a name="SecIII_6" id="SecIII_6"></a>VALUE OF INDICATOR CARDS</h3>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig013" id="Fig013"></a>
+<img src="images/illo062a.png" alt="Fig. 13" width="500" height="224" />
+<p class="caption">Fig. 13.&mdash;Otto Four-Cycle Card.</p></div>
+
+<p>To the uninitiated, indicator cards are considerable
+of a mystery; to those capable of reading them they form
+an index relative to the action of any engine. An indicator
+card, such as shown at <a href="#Fig013">Fig. 13</a>, is merely a graphical
+representation of the various pressures existing in the
+cylinder for different positions of the piston. The length
+is to some scale that represents the stroke of the piston.
+During the intake stroke, the pressure falls below the<span class='pagenum'><a name="Page_67" id="Page_67">[67]</a></span>
+atmospheric line. During compression, the curve gradually
+becomes higher owing to increasing pressure as the
+volume is reduced. After ignition the pressure line moves
+upward almost straight, then as the piston goes down on
+the explosion stroke, the pressure falls gradually to the
+point of exhaust valve, opening when the sudden release
+of the imprisoned gas causes a reduction in pressure to
+nearly atmospheric. An indicator card, or a series of
+them, will always show by its lines the normal or defective
+condition of the inlet valve and passages; the actual line
+of compression; the firing moment; the pressure of explosion;
+the velocity of combustion; the normal or defective
+line of expansion, as measured by the adiabatic curve,<span class='pagenum'><a name="Page_68" id="Page_68">[68]</a></span>
+and the normal or defective operation of the exhaust
+valve, exhaust passages, and exhaust pipe. In fact, all
+the cycles of an explosive motor may be made a practical
+study from a close investigation of the lines of an indicator
+card.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig014" id="Fig014"></a>
+<img src="images/illo062b.png" alt="Fig. 14" width="500" height="273" />
+<p class="caption">Fig. 14.&mdash;Diesel Motor Card.</p></div>
+
+<p>A most unique card is that of the Diesel motor (<a href="#Fig014">Fig.
+14</a>), which involves a distinct principle in the design and
+operation of internal-combustion motors, in that instead
+of taking a mixed charge for instantaneous explosion, its
+charge primarily is of air and its compression to a pressure
+at which a temperature is attained above the igniting
+point of the fuel, then injecting the fuel under a still
+higher pressure by which spontaneous combustion takes
+place gradually with increasing volume over the compression
+for part of the stroke or until the fuel charge is consumed.
+The motor thus operating between the pressures
+of 500 and 35 lbs. per square inch, with a clearance of
+about 7 per cent., has given an efficiency of 36 per cent.
+of the total heat value of kerosene oil.</p>
+
+<h3><a name="SecIII_7" id="SecIII_7"></a>COMPRESSION IN EXPLOSIVE MOTORS</h3>
+
+<p>That the compression in a gas, gasoline, or oil-engine
+has a direct relation to the power obtained, has been long
+known to experienced builders, having been suggested by
+M. Beau de Rocha, in 1862, and afterward brought into
+practical use in the four-cycle or Otto type about 1880.
+The degree of compression has had a growth from zero,
+in the early engines, to the highest available due to the
+varying ignition temperatures of the different gases and
+vapors used for explosive fuel, in order to avoid premature
+explosion from the heat of compression. Much of
+the increased power for equal-cylinder capacity is due to
+compression of the charge from the fact that the most
+powerful explosion of gases, or of any form of explosive
+material, takes place when the particles are in the closest
+contact or cohesion with one another, less energy in this
+form being consumed by the ingredients themselves to
+bring about their chemical combination, and consequently<span class='pagenum'><a name="Page_69" id="Page_69">[69]</a></span>
+more energy is given out in useful or available work.
+This is best shown by the ignition of gunpowder, which,
+when ignited in the open air, burns rapidly, but without
+explosion, an explosion only taking place if the powder
+be confined or compressed into a small space.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig015" id="Fig015"></a>
+<img src="images/illo064.png" alt="Fig. 15" width="400" height="457" />
+<p class="caption">Fig. 15.&mdash;Diagram of Heat in the Gas Engine Cylinder.</p></div>
+
+<p>In a gas or gasoline-motor with a small clearance or
+compression space&mdash;with high compression&mdash;the surface
+with which the burning gases come into contact is much
+smaller in comparison with the compression space in a
+low-compression motor. Another advantage of a high-compression
+motor is that on account of the smaller clearance
+of combustion space less cooling water is required
+than with a low-compression motor, as the temperature,<span class='pagenum'><a name="Page_70" id="Page_70">[70]</a></span>
+and consequently the pressure, falls more rapidly. The
+loss of heat through the water-jacket is thus less in the
+case of a high-compression than in that of a low-compression
+motor. In the non-compression type of motor the
+best results were obtained with a charge of 16 to 18 parts
+of gas and 100 parts of air, while in the compression type
+the best results are obtained with an explosive mixture
+of 7 to 10 parts of gas and 100 parts of air, thus showing
+that by the utilization of compression a weaker charge
+with a greater thermal efficiency is permissible.</p>
+
+<p>It has been found that the explosive pressure resulting
+from the ignition of the charge of gas or gasoline-vapor
+and air in the gas-engine cylinder is about 4<sup>1</sup>&#8260;<sub>2</sub> times the
+pressure prior to ignition. The difficulty about getting
+high compression is that if the pressure is too high the
+charge is likely to ignite prematurely, as compression
+always results in increased temperature. The cylinder
+may become too hot, a deposit of carbon, a projecting
+electrode or plug body in the cylinder may become incandescent
+and ignite the charge which has been excessively
+heated by the high compression and mixture of
+the hot gases of the previous explosion.</p>
+
+<h3><a name="SecIII_8" id="SecIII_8"></a>FACTORS LIMITING COMPRESSION</h3>
+
+<p>With gasoline-vapor and air the compression should not
+be raised above about 90 to 95 pounds to the square inch,
+many manufacturers not going above 65 or 70 pounds.
+For natural gas the compression pressure may easily be
+raised to from 85 to 100 pounds per square inch. For
+gases of low calorific value, such as blast-furnace or producer-gas,
+the compression may be increased to from 140
+to 190 pounds. In fact the ability to raise the compression
+to a high point with these gases is one of the principal
+reasons for their successful adoption for gas-engine
+use. In kerosene injection engines the compression of 250
+pounds per square inch has been used with marked economy.
+Many troubles in regard to loss of power and increase
+of fuel have occurred and will no doubt continue,<span class='pagenum'><a name="Page_71" id="Page_71">[71]</a></span>
+owing to the wear of valves, piston, and cylinder, which
+produces a loss in compression and explosive pressure
+and a waste of fuel by leakage. Faulty adjustment of
+valve movement is also a cause of loss of power; which
+may be from tardy closing of the inlet-valve or a too early
+opening of the exhaust-valve.</p>
+
+<p>The explosive pressure varies to a considerable amount
+in proportion to the compression pressure by the difference
+in fuel value and the proportions of air mixtures,
+so that for good illuminating gas the explosive pressure
+may be from 2.5 to 4 times the compression pressure.
+For natural gas 3 to 4.5, for gasoline 3 to 5, for producer-gas
+2 to 3, and for kerosene by injection 3 to 6.</p>
+
+<p>The compression temperatures, although well known
+and easily computed from a known normal temperature
+of the explosive mixture, are subject to the effect of the
+uncertain temperature of the gases of the previous explosion
+remaining in the cylinder, the temperature of its
+walls, and the relative volume of the charge, whether full
+or scant; which are terms too variable to make any computations
+reliable or available.</p>
+
+<p>For the theoretical compression temperatures from a
+known normal temperature, we append a table of the rise
+in temperature for the compression pressures in the following
+table:</p>
+
+<h5><span class="smcap">Table IV.&mdash;Compression Temperatures<br />from a Normal Temperature of<br />
+60 Degrees Fahrenheit</span></h5>
+
+<table class="fsize80" summary="table p 71">
+
+<tr class="bt2">
+<td class="right padl1 padr1">100</td>
+<td class="center">&nbsp;lbs.&nbsp;</td>
+<td class="left padr6">gauge</td>
+<td class="right br padr1">484&deg;</td>
+<td class="right padl1 padr1">60</td>
+<td class="center">&nbsp;lbs.&nbsp;</td>
+<td class="left padr6">gauge</td>
+<td class="right padr1">373&deg;</td>
+</tr>
+
+<tr>
+<td class="right padl1 padr1">90</td>
+<td class="center">&nbsp;lbs.&nbsp;</td>
+<td class="left padr6">gauge</td>
+<td class="right br padr1">459&deg;</td>
+<td class="right padl1 padr1">50</td>
+<td class="center">&nbsp;lbs.&nbsp;</td>
+<td class="left padr6">gauge</td>
+<td class="right padr1">339&deg;</td>
+</tr>
+
+<tr>
+<td class="right padl1 padr1">80</td>
+<td class="center">&nbsp;lbs.&nbsp;</td>
+<td class="left padr6">gauge</td>
+<td class="right br padr1">433&deg;</td>
+<td class="right padl1 padr1">40</td>
+<td class="center">&nbsp;lbs.&nbsp;</td>
+<td class="left padr6">gauge</td>
+<td class="right padr1">301&deg;</td>
+</tr>
+
+<tr class="bb">
+<td class="right padl1 padr1">70</td>
+<td class="center">&nbsp;lbs.&nbsp;</td>
+<td class="left padr6">gauge</td>
+<td class="right br padr1">404&deg;</td>
+<td class="right padl1 padr1">30</td>
+<td class="center">&nbsp;lbs.&nbsp;</td>
+<td class="left padr6">gauge</td>
+<td class="right padr1">258&deg;</td>
+</tr>
+
+</table>
+
+<h3>CHART FOR DETERMINING COMPRESSION PRESSURES</h3>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig016" id="Fig016"></a>
+<img src="images/illo067.png" alt="Fig. 16" width="500" height="402" />
+<p class="caption">Fig. 16.&mdash;Chart Showing Relation Between Compression Volume
+and Pressure.</p></div>
+
+<p>A very useful chart (<a href="#Fig016">Fig. 16</a>) for determining compression
+pressures in gasoline-engine cylinders for various
+ratios of compression space to total cylinder volume
+is given by P. S. Tice, and described in the Chilton Automobile
+Directory by the originator as follows:</p>
+
+<p><span class='pagenum'><a name="Page_72" id="Page_72">[72]</a></span>It is many times desirable to have at hand a convenient
+means for at once determining with accuracy what
+the compression pressure will be in a gasoline-engine cylinder,
+the relationship between the volume of the compression
+space and the total cylinder volume or that swept
+by the piston being known. The curve at <a href="#Fig016">Fig. 16</a> is
+offered as such a means. It is based on empirical data
+gathered from upward of two dozen modern automobile
+engines and represents what may be taken to be the results
+as found in practice. It is usual for the designer to find
+compression pressure values, knowing the volumes from
+the equation</p>
+
+<table class="formula" summary="formula p 72">
+
+<tr>
+<td rowspan="2" class="left">P<sub>2</sub> = P<sub>1</sub> <span class="fsize150">(</span></td>
+<td class="center bb">V<sub>1</sub></td>
+<td rowspan="2" class="left"><span class="fsize150">)</span><sup class="top">1.4</sup></td>
+<td rowspan="2" class="padl6">1</td>
+</tr>
+
+<tr>
+<td class="center">V<sub>2</sub></td>
+</tr>
+
+</table>
+
+<p>which is for adiabatic compression of air. Equation (1)
+is right enough in general form but gives results which<span class='pagenum'><a name="Page_73" id="Page_73">[73]</a></span>
+are entirely too high, as almost all designers know from
+experience. The trouble lies in the interchange of heat
+between the compressed gases and the cylinder walls, in
+the diminution of the exponent (1.4 in the above) due to the
+lesser ratio of specific heat of gasoline vapor and in the
+transfer of heat from the gases which are being compressed
+to whatever fuel may enter the cylinder in an
+unvaporized condition. Also, there is always some piston
+leakage, and, if the form of the equation (1) is to be
+retained, this also tends to lower the value of the exponent.
+From experience with many engines, it appears
+that compression reaches its highest value in the cylinder
+for but a short range of motor speeds, usually during the
+mid-range. Also, it appears that, at those speeds at which
+compression shows its highest values, the initial pressure
+at the start of the compression stroke is from .5 to .9 lb.
+below atmospheric. Taking this latter loss value, which
+shows more often than those of lesser value, the compression
+is seen to start from an initial pressure of 13.9 lbs.
+per sq. in. absolute.</p>
+
+<p>Also, experiment shows that if the exponent be given
+the value 1.26, instead of 1.4, the equation will embrace
+all heat losses in the compressed gas, and compensate for
+the changed ratio of specific heats for the mixture and
+also for all piston leakage, in the average engine with
+rings in good condition and tight. In the light of the
+foregoing, and in view of results obtained from its use,
+the above curve is offered&mdash;values of P<sub>2</sub> being found
+from the equation</p>
+
+<table class="formula" summary="formula p 73">
+
+<tr>
+<td rowspan="2" class="left">P<sub>2</sub> = 13.8 <span class="fsize150">(</span></td>
+<td class="center bb">V<sub>1</sub></td>
+<td rowspan="2" class="left"><span class="fsize150">)</span><sup class="top">1.26</sup></td>
+</tr>
+
+<tr>
+<td class="center">V<sub>2</sub></td>
+</tr>
+
+</table>
+
+<p>In using this curve it must be remembered that pressures
+are absolute. Thus: suppose it is desired to know
+the volumetric relationships of the cylinder for a compression
+pressure of 75 lbs. gauge. Add atmospheric
+pressure to the desired gauge pressure 14.7 + 75 = 89.7
+lbs. absolute. Locate this pressure on the scale of ordinates<span class='pagenum'><a name="Page_74" id="Page_74">[74]</a></span>
+and follow horizontally across to the curve and then
+vertically downward to the scale of abscissas, where the
+ratio of the combustion chamber volume to the total cylinder
+volume is given, which latter is equal to the sum of
+the combustion chamber volume and that of the piston
+sweep. In the above case it is found that the combustion
+space for a compression pressure of 75 lbs. gauge will be
+.225 of the total cylinder volume, or .225 &divide; .775 = .2905
+of the piston sweep volume. Conversely, knowing the
+volumetric ratios, compression pressure can be read directly
+by proceeding from the scale of abscissas vertically
+to the curve and thence horizontally to the scale of
+ordinates.</p>
+
+<h3><a name="SecIII_9" id="SecIII_9"></a>CAUSES OF HEAT LOSS AND INEFFICIENCY IN EXPLOSIVE MOTORS</h3>
+
+<p>The difference realized in the practical operation of
+an internal combustion heat engine from the computed
+effect derived from the values of the explosive elements
+is probably the most serious difficulty that engineers have
+encountered in their endeavors to arrive at a rational
+conclusion as to where the losses were located, and the
+ways and means of design that would eliminate the causes
+of loss and raise the efficiency step by step to a reasonable
+percentage of the total efficiency of a perfect cycle.</p>
+
+<p>An authority on the relative condition of the chemical
+elements under combustion in closed cylinders attributes
+the variation of temperature shown in the fall of the expansion
+curve, and the suppression or retarded evolution
+of heat, entirely to the cooling action of the cylinder walls,
+and to this nearly all the phenomena hitherto obscure in
+the cylinder of a gas-engine. Others attribute the great
+difference between the theoretical temperature of combustion
+and the actual temperature realized in the practical
+operation of the gas-engine, a loss of more than one-half
+of the total heat energy of the combustibles, partly to the
+dissociation of the elements of combustion at extremely
+high temperatures and their reassociation by expansion
+in the cylinder, to account for the supposed continued<span class='pagenum'><a name="Page_75" id="Page_75">[75]</a></span>
+combustion and extra adiabatic curve of the expansion
+line on the indicator card.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig017" id="Fig017"></a>
+<img src="images/illo070.jpg" alt="Fig. 17" width="400" height="463" />
+<p class="caption">Fig. 17.&mdash;The Thompson Indicator, an Instrument for Determining Compressions
+and Explosion Pressure Values and Recording Them on Chart.</p></div>
+
+<p>The loss of heat to the walls of the cylinder, piston,
+and clearance space, as regards the proportion of wall
+surface to the volume, has gradually brought this point
+to its smallest ratio in the concave piston-head and globular
+cylinder-head, with the smallest possible space in the
+inlet and exhaust passage. The wall surface of a cylindrical
+clearance space or combustion chamber of one-half
+its unit diameter in length is equal to 3.1416 square units,
+its volume but 0.3927 of a cubic unit; while the same wall<span class='pagenum'><a name="Page_76" id="Page_76">[76]</a></span>
+surface in a spherical form has a volume of 0.5236 of a
+cubic unit. It will be readily seen that the volume is increased
+33<sup>1</sup>&#8260;<sub>3</sub> per cent. in a spherical over a cylindrical
+form for equal wall surfaces at the moment of explosion,
+when it is desirable that the greatest amount of heat is
+generated, and carrying with it the greatest possible pressure
+from which the expansion takes place by the movement
+of the piston.</p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig018" id="Fig018"></a>
+<img src="images/illo071a.png" alt="Fig. 18" width="350" height="205" />
+<p class="caption">Fig. 18.&mdash;Spherical Combustion
+Chamber.</p></div>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig019" id="Fig019"></a>
+<img src="images/illo071b.png" alt="Fig. 19" width="350" height="210" />
+<p class="caption">Fig. 19.&mdash;Enlarged Combustion
+Chamber.</p></div>
+
+<p>The spherical form cannot continue during the stroke
+for mechanical reasons; therefore some proportion of
+piston stroke of cylinder volume must be found to correspond
+with a spherical form of the combustion chamber
+to produce the least loss of heat through the walls during
+the combustion and expansion part of the stroke. This
+idea is illustrated in <a href="#Fig018">Figs. 18</a> and <a href="#Fig019">19</a>, showing how the
+relative volumes of cylinder stroke and combustion chamber
+may be varied to suit the requirements due to the
+quality of the elements of combustion.</p>
+
+<p>Although the concave piston-head shows economy in
+regard to the relation of the clearance volume to the wall
+area at the moment of explosive combustion, it may be
+clearly seen that its concavity increases its surface area
+and its capacity for absorbing heat, for which there is
+no provision for cooling the piston, save its contact with
+the walls of the cylinder and the slight air cooling of its
+back by its reciprocal motion. For this reason the concave
+piston-head has not been generally adopted and the
+concave cylinder-head, as shown in <a href="#Fig019">Fig. 19</a>, with a flat<span class='pagenum'><a
+name="Page_78" id="Page_78">[78]</a></span><span class='pagenum'><a name="Page_77" id="Page_77"></a></span>
+piston-head is the latest and best practice in airplane
+engine construction.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig020" id="Fig020"></a>
+<img src="images/illo072.png" alt="Fig. 20" width="400" height="548" />
+<p class="caption">Fig. 20.&mdash;Mercedes Aviation Engine Cylinder Section Showing Approximately
+Spherical Combustion Chamber and Concave Piston Top.</p></div>
+
+<p>The practical application of the principle just outlined
+to one of the most efficient airplane motors ever designed,
+the Mercedes, is clearly outlined at <a href="#Fig020">Fig. 20</a>.</p>
+
+<h3><a name="SecIII_10" id="SecIII_10"></a>HEAT LOSSES TO COOLING WATER</h3>
+
+<p>The mean temperature of the wall surface of the combustion
+chamber and cylinder, as indicated by the temperatures
+of the circulating water, has been found to be
+an important item in the economy of the gas-engine.
+Dugald Clerk, in England, a high authority in practical
+work with the gas-engine, found that 10 per cent. of the
+gas for a stated amount of power was saved by using
+water at a temperature in which the ejected water from
+the cylinder-jacket was near the boiling-point, and ventures
+the opinion that a still higher temperature for the
+circulating water may be used as a source of economy.
+This could be made practical in the case of aviation engines
+by adjusting the air-cooling surface of the radiator
+so as to maintain the inlet water at just below the boiling
+point, and by the rapid circulation induced by the pump
+pressure, to return the water from the cylinder-jacket a
+few degrees above the boiling point. The thermal displacement
+systems of cooling employed in automobiles
+are working under more favorable temperature conditions
+than those engines in which cooling is more energetic.</p>
+
+<p>For a given amount of heat taken from the cylinder
+by the largest volume of circulating water, the difference
+in temperature between inlet and outlet of the water-jacket
+should be the least possible, and this condition of
+the water circulation gives a more even temperature to
+all parts of the cylinder; while, on the contrary, a cold-water
+supply, say at <span class="nowrap">60&deg;</span> F., so slow as to allow the ejected
+water to flow off at a temperature near the boiling-point,
+must make a great difference in temperature between the
+bottom and top of the cylinder, with a loss in economy<span class='pagenum'><a name="Page_79" id="Page_79">[79]</a></span>
+in gas and other fuels, as well as in water, if it is obtained
+by measurement.</p>
+
+<p>From the foregoing considerations of losses and inefficiencies,
+we find that the practice in motor design and
+construction has not yet reached the desired perfection
+in its cycular operation. Step by step improvements have
+been made with many changes in design though many
+have been without merit as an improvement, farther than
+to gratify the longings of designers for something different
+from the other thing, and to establish a special
+construction of their own. These efforts may in time
+produce a motor of normal or standard design for each
+kind of fuel that will give the highest possible efficiency
+for all conditions of service.</p>
+
+<hr class="c25" />
+<p class='pagenum'><a name="Page_80" id="Page_80">[80]</a></p>
+<h2><a name="ChIV" id="ChIV"></a>CHAPTER IV</h2>
+
+<div class="chapsec"><p><a href="#SecIV_1">Engine Parts and Functions</a>&mdash;<a href="#SecIV_2">Why Multiple Cylinder Engines Are
+Best</a>&mdash;<a href="#SecIV_3">Describing Sequence of Operations</a>&mdash;<a
+href="#SecIV_4">Simple Engines</a>&mdash;<a href="#SecIV_5">Four
+and Six Cylinder Vertical Tandem Engines</a>&mdash;<a href="#SecIV_6">Eight and Twelve
+Cylinder V Engines</a>&mdash;<a href="#SecIV_7">Radial Cylinder Arrangement</a>&mdash;<a href="#SecIV_8">Rotary Cylinder
+Forms</a>.</p></div>
+
+<h3><a name="SecIV_1" id="SecIV_1"></a>ENGINE PARTS AND FUNCTIONS</h3>
+
+<p>The principal elements of a gas engine are not difficult
+to understand and their functions are easily defined.
+In place of the barrel of the gun one has a smoothly
+machined cylinder in which a small cylindrical or barrel-shaped
+element fitting the bore closely may be likened to
+a bullet or cannon ball. It differs in this important
+respect, however, as while the shot is discharged from
+the mouth of the cannon the piston member sliding inside
+of the main cylinder cannot leave it, as its movements
+back and forth from the open to the closed end and back
+again are limited by simple mechanical connection or linkage
+which comprises crank and connection rod. It is by
+this means that the reciprocating movement of the piston
+is transformed into a rotary motion of the crank-shaft.</p>
+
+<p>The fly-wheel is a heavy member attached to the crank-shaft
+of an automobile engine which has energy stored
+in its rim as the member revolves, and the momentum
+of this revolving mass tends to equalize the intermittent
+pushes on the piston head produced by the explosion of
+the gas in the cylinder. In aviation engines, the weight
+of the propeller or that of rotating cylinders themselves
+performs the duty of a fly-wheel, so no separate member
+is needed. If some explosive is placed in the chamber
+formed by the piston and closed end of the cylinder and
+exploded, the piston would be the only part that would
+yield to the pressure which would produce a downward
+movement. As this is forced down the crank-shaft is<span class='pagenum'><a
+name="Page_82" id="Page_82">[82]</a></span><span class='pagenum'><a name="Page_81" id="Page_81"></a></span>
+turned by the connecting rod, and as this part is hinged
+at both ends it is free to oscillate as the crank turns, and
+thus the piston may slide back and forth while the crank-shaft
+is rotating or describing a curvilinear path.</p>
+
+<div class="figcenter" style="width: 650px;"><a name="Fig021" id="Fig021"></a>
+<p class="leftlink"><a href="images/large076.png">Large<br />image<br />(135 kB).</a></p>
+<img src="images/illo076.png" alt="Fig. 21" width="600" height="366" />
+<p class="caption">Fig. 21.&mdash;Side Sectional View of Typical Airplane Engine, Showing Parts and Their Relation to Each Other.
+This Engine is an Aeromarine Design and Utilizes a Distinctive Concentric Valve Construction.</p></div>
+
+<p>In addition to the simple elements described it is evident
+that a gasoline engine must have other parts. The
+most important of these are the valves, of which there are
+generally two to each cylinder. One closes the passage
+connecting to the gas supply and opens during one stroke
+of the piston in order to let the explosive gas into the
+combustion chamber. The other member, or exhaust
+valve, serves as a cover for the opening through which
+the burned gases can leave the cylinder after their work
+is done. The spark plug is a simple device which may
+be compared to the fuse or percussion cap of the cannon.
+It permits one to produce an electric spark in the cylinder
+when the piston is at the best point to utilize the
+pressure which obtains when the compressed gas is fired.
+The valves are open one at a time, the inlet valve being
+lifted from its seat while the cylinder is filling and the
+exhaust valve is opened when the cylinder is being cleared.
+They are normally kept seated by means of compression
+springs. In the simple motor shown at <a href="#Fig005">Fig. 5</a>, the exhaust
+valve is operated by means of a pivoted bell crank rocked
+by a cam which turns at half the speed of the crank-shaft.
+The inlet valve operates automatically, as will be explained
+in proper sequence.</p>
+
+<p>In order to obtain a perfectly tight combustion chamber,
+both intake and exhaust valves are closed before the
+gas is ignited, because all of the pressure produced by
+the exploding gas is to be directed against the top of
+the movable piston. When the piston reaches the bottom
+of its power stroke, the exhaust valve is lifted by means
+of the bell crank which is rocked because of the point or
+lift on the cam. The cam-shaft is driven by positive
+gearing and revolves at half the engine speed. The exhaust
+valve remains open during the whole of the return
+stroke of the piston, and as this member moves toward<span class='pagenum'><a name="Page_83" id="Page_83">[83]</a></span>
+the closed end of the cylinder it forces out burned gases
+ahead of it, through the passage controlled by the exhaust
+valve. The cam-shaft is revolved at half the engine speed
+because the exhaust valve is raised from its seat during
+only one stroke out of four, or only once every two revolutions.
+Obviously, if the cam was turned at the same
+speed as the crank-shaft it would remain open once every
+revolution, whereas the burned gases are expelled from
+the individual cylinders only once in two turns of the
+crank-shaft.</p>
+
+<h3><a name="SecIV_2" id="SecIV_2"></a>WHY MULTIPLE CYLINDER FORMS ARE BEST</h3>
+
+<p>Owing to the vibration which obtains from the heavy
+explosion in the large single-cylinder engines used for
+stationary power other forms were evolved in which the
+cylinder was smaller and power obtained by running the
+engine faster, but these are suitable only for very low
+powers.</p>
+
+<p>When a single-cylinder engine is employed a very
+heavy fly-wheel is needed to carry the moving parts
+through idle strokes necessary to obtain a power impulse.
+For this reason automobile and aircraft designers
+must use more than one cylinder, and the tendency
+is to produce power by frequently occurring light impulses
+rather than by a smaller number of explosions
+having greater force. When a single-cylinder motor is
+employed the construction is heavier than is needed with
+a multiple-cylinder form. Using two or more cylinders
+conduces to steady power generation and a lessening of
+vibration. Most modern motor cars employ four-cylinder
+engines because a power impulse may be secured twice
+every revolution of the crank-shaft, or a total of four power
+strokes during two revolutions. The parts are so
+arranged that while the charge of gas in one cylinder is
+exploding, those which come next in firing order are compressing,
+discharging the inert gases and drawing in a
+fresh charge respectively. When the power stroke is
+completed in one cylinder, the piston in that member in<span class='pagenum'><a name="Page_84" id="Page_84">[84]</a></span>
+which a charge of gas has just been compressed has
+reached the top of its stroke and when the gas is exploded
+the piston is reciprocated and keeps the crank-shaft
+turning. When a multiple-cylinder engine is used
+the fly-wheel can be made much lighter than that of the
+simpler form and eliminated altogether in some designs.
+In fact, many modern multiple-cylinder engines developing
+300 horse-power weigh less than the early single- and
+double-cylinder forms which developed but one-tenth or
+one-twentieth that amount of energy.</p>
+
+<h3><a name="SecIV_3" id="SecIV_3"></a><a name="SecIV_4" id="SecIV_4"></a>DESCRIBING SEQUENCE OF OPERATIONS</h3>
+
+<p>Referring to <a href="#Fig022">Fig. 22</a>, A, the sequence of operation in
+a single-cylinder motor can be easily understood. Assuming
+that the crank-shaft is turning in the direction
+of the arrow, it will be seen that the intake stroke comes
+first, then the compression, which is followed by the power
+impulse, and lastly the exhaust stroke. If two cylinders
+are used, it is possible to balance the explosions in such
+a way that one will occur each revolution. This is true
+with either one of two forms of four-cycle motors. At
+B, a two-cylinder vertical engine using a crank-shaft in
+which the crank-pins are on the same plane is shown.
+The two pistons move up and down simultaneously. Referring
+to the diagram describing the strokes, and assuming
+that the outer circle represents the cycle of operations
+in one cylinder while the inner circle represents the sequence
+of events in the other cylinder, while cylinder
+No. 1 is taking in a fresh charge of gas, cylinder No. 2
+is exploding. When cylinder No. 1 is compressing, cylinder
+No. 2 is exhausting. During the time that the charge
+in cylinder No. 1 is exploded, cylinder No. 2 is being filled
+with fresh gas. While the exhaust gases are being discharged
+from cylinder No. 1, cylinder No. 2 is compressing
+the gas previously taken.</p>
+
+<p class='pagenum'><a name="Page_85" id="Page_85">[85]</a></p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig022" id="Fig022"></a>
+<img src="images/illo080.png" alt="Fig. 22" width="350" height="548" />
+<p class="caption">Fig. 22.&mdash;Diagrams Illustrating Sequence of Cycles in One- and Two-Cylinder
+Engines Showing More Uniform Turning Effort on Crank-Shaft with
+Two-Cylinder Motors.</p></div>
+
+<p>The same condition obtains when the crank-pins are
+arranged at one hundred and eighty degrees and the cylinders
+are opposed, as shown at C. The reason that the<span class='pagenum'><a name="Page_86" id="Page_86">[86]</a></span>
+two-cylinder opposed motor is more popular than that
+having two vertical cylinders is that it is difficult to balance
+the construction shown at B, so that the vibration
+will not be excessive. The two-cylinder opposed motor
+has much less vibration than the other form, and as the
+explosions occur evenly and the motor is a simple one
+to construct, it has been very popular in the past on
+light cars and has received limited application on some
+early, light airplanes.</p>
+
+<p class='pagenum'><a name="Page_87" id="Page_87">[87]</a></p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig023" id="Fig023"></a>
+<img src="images/illo082.png" alt="Fig. 23" width="350" height="548" />
+<p class="caption">Fig. 23.&mdash;Diagrams Demonstrating Clearly Advantages which Obtain when
+Multiple-Cylinder Motors are Used as Power Plants.</p></div>
+
+<p>To demonstrate very clearly the advantages of multiple-cylinder
+engines the diagrams at <a href="#Fig023">Fig. 23</a> have been
+prepared. At A, a three-cylinder motor, having crank-pins
+at one hundred and twenty degrees, which means that
+they are spaced at thirds of the circle, we have a form
+of construction that gives a more even turning than that
+possible with a two-cylinder engine. Instead of one explosion
+per revolution of the crank-shaft, one will obtain
+three explosions in two revolutions. The manner in which
+the explosion strokes occur and the manner they overlap
+strokes in the other cylinder is shown at A. Assuming
+that the cylinders fire in the following order, first No. 1,
+then No. 2, and last No. 3, we will see that while cylinder
+No. 1, represented by the outer circle, is on the power
+stroke, cylinder No. 3 has completed the last two-thirds
+of its exhaust stroke and has started on its intake stroke.
+Cylinder No. 2, represented by the middle circle, during
+this same period has completed its intake stroke and two-thirds
+of its compression stroke. A study of the diagram
+will show that there is an appreciable lapse of time between
+each explosion.</p>
+
+<p>Three-cylinder engines are not used on aircraft at the
+present time, though Bleriot&#8217;s flight across the British
+Channel was made with a three-cylinder Anzani motor.
+It was not a conventional form, however. The three-cylinder
+engine is practically obsolete at this time for any
+purpose except &#8220;penguins&#8221; or school machines that are
+incapable of flight and which are used in some French
+training schools for aviators.</p>
+
+<p class='pagenum'><a name="Page_88" id="Page_88">[88]</a></p>
+
+<h3><a name="SecIV_5" id="SecIV_5"></a>FOUR- AND SIX-CYLINDER ENGINES</h3>
+
+<p>In the four-cylinder engine operation which is shown
+at <a href="#Fig023">Fig. 23</a>, B, it will be seen that the power strokes follow
+each other without loss of time, and one cylinder begins
+to fire and the piston moves down just as soon as the
+member ahead of it has completed its power stroke. In
+a four-cylinder motor, the crank-pins are placed at one
+hundred and eighty degrees, or on the halves of the crank
+circle. The crank-pins for cylinders No. 1 and No. 4 are
+on the same plane, while those for cylinders No. 2 and
+No. 3 also move in unison. The diagram describing sequence
+of operations in each cylinder is based on a firing
+order of one, two, four, three. The outer circle, as in
+previous instances, represents the cycle of operations in
+cylinder one. The next one toward the center, cylinder
+No. 2, the third circle represents the sequence of events
+in cylinder No. 3, while the inner circle outlines the strokes
+in cylinder four. The various cylinders are working as
+follows:</p>
+
+<table summary="table p 88">
+
+<tr>
+<td class="center">1.</td>
+<td class="center">2.</td>
+<td class="center">3.</td>
+<td class="center">4.</td>
+</tr>
+
+<tr>
+<td class="left">Explosion</td>
+<td class="left padr3">Compression</td>
+<td class="left">Exhaust</td>
+<td class="left">Intake</td>
+</tr>
+
+<tr>
+<td class="left">Exhaust</td>
+<td class="left">Explosion</td>
+<td class="left">Intake</td>
+<td class="left padr3">Compression</td>
+</tr>
+
+<tr>
+<td class="left">Intake</td>
+<td class="left">Exhaust</td>
+<td class="left padr3">Compression</td>
+<td class="left">Explosion</td>
+</tr>
+
+<tr>
+<td class="left padr3">Compression</td>
+<td class="left">Intake</td>
+<td class="left">Explosion</td>
+<td class="left">Exhaust</td>
+</tr>
+
+</table>
+
+<p>It will be obvious that regardless of the method of
+construction, or the number of cylinders employed, exactly
+the same number of parts must be used in each
+cylinder assembly and one can conveniently compare
+any multiple-cylinder power plant as a series of single-cylinder
+engines joined one behind the other and so
+coupled that one will deliver power and produce useful
+energy at the crank-shaft where the other leaves off.
+The same fundamental laws governing the action of a
+single cylinder obtain when a number are employed, and
+the sequence of operation is the same in all members, except
+that the necessary functions take place at different<span class='pagenum'><a name="Page_89" id="Page_89">[89]</a></span>
+times. If, for instance, all the cylinders of a four-cylinder
+motor were fired at the same time, one would obtain
+the same effect as though a one-piston engine was used,
+which had a piston displacement equal to that of the four
+smaller members. As is the case with a single-cylinder
+engine, the motor would be out of correct mechanical balance
+because all the connecting rods would be placed on
+crank-pins that lie in the same plane. A very large fly-wheel
+would be necessary to carry the piston through the
+idle strokes, and large balance weights would be fitted to
+the crank-shaft in an effort to compensate for the weight
+of the four pistons, and thus reduce vibratory stresses
+which obtain when parts are not in correct balance.</p>
+
+<p>There would be no advantage gained by using four
+cylinders in this manner, and there would be more loss of
+heat and more power consumed in friction than in a one-piston
+motor of the same capacity. This is the reason
+that when four cylinders are used the arrangement of
+crank-pins is always as shown at <a href="#Fig023">Fig. 23</a>, B&mdash;i.e., two
+pistons are up, while the other two are at the bottom of
+the stroke. With this construction, we have seen that it
+is possible to string out the explosions so that there will
+always be one cylinder applying power to the crank-shaft.
+The explosions are spaced equally. The parts are in
+correct mechanical balance because two pistons are on the
+upstroke while the other two are descending. Care is
+taken to have one set of moving members weigh exactly
+the same as the other. With a four-cylinder engine one
+has correct balance and continuous application of energy.
+This insures a smoother running motor which has greater
+efficiency than the simpler one-, two-, and three-cylinder
+forms previously described. Eliminating the stresses
+which would obtain if we had an unbalanced mechanism
+and irregular power application makes for longer life.
+Obviously a large number of relatively light explosions
+will produce less wear and strain than would a lesser
+number of powerful ones. As the parts can be built lighter
+if the explosions are not heavy, the engine can be operated<span class='pagenum'><a name="Page_90" id="Page_90">[90]</a></span>
+at higher rotative speeds than when large and cumbersome
+members are utilized. Four-cylinder engines
+intended for aviation work have been built according to
+the designs shown at <a href="#Fig024">Fig. 24</a>, but these forms are unconventional
+and seldom if ever used.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig024" id="Fig024"></a>
+<img src="images/illo085.png" alt="Fig. 24" width="500" height="363" />
+<p class="caption">Fig. 24.&mdash;Showing Three Possible Though Unconventional Arrangements of
+Four-Cylinder Engines.</p></div>
+
+<p>The six-cylinder type of motor, the action of which is
+shown at <a href="#Fig023">Fig. 23</a>, C, is superior to the four-cylinder, inasmuch
+as the power strokes overlap, and instead of having
+two explosions each revolution we have three explosions.
+The conventional crank-shaft arrangement in a six-cylinder
+engine is just the same as though one used two three-cylinder
+shafts fastened together, so pistons 1 and 6 are
+on the same plane as are pistons 2 and 5. Pistons 3 and
+4 also travel together. With the cranks arranged as outlined
+at <a href="#Fig023">Fig. 23</a>, C, the firing order is one, five, three, six,
+two, four. The manner in which the power strokes overlap
+is clearly shown in the diagram. An interesting comparison<span class='pagenum'><a name="Page_91" id="Page_91">[91]</a></span>
+is also made in the diagrams at <a href="#Fig025">Fig. 25</a> and in the
+upper corner of <a href="#Fig023">Fig. 23</a>, C.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig025" id="Fig025"></a>
+<p class="leftlink"><a href="images/large086.png">Large<br />scale<br />image<br />(84 kB).</a></p>
+<img src="images/illo086.png" alt="Fig. 25" width="600" height="519" />
+<p class="caption">Fig. 25.&mdash;Diagrams Outlining Advantages of Multiple Cylinder Motors, and
+Why They Deliver Power More Evenly Than Single Cylinder Types.</p></div>
+
+<p>A rectangle is divided into four columns; each of these
+corresponds to one hundred and eighty degrees, or half a
+revolution. Thus the first revolution of the crank-shaft
+is represented by the first two columns, while the second
+revolution is represented by the last two. Taking the portion
+of the diagram which shows the power impulse in a
+one-cylinder engine, we see that during the first revolution
+there has been no power impulse. During the first half
+of the second revolution, however, an explosion takes place
+and a power impulse is obtained. The last portion of the
+second revolution is devoted to exhausting the burned
+gases, so that there are three idle strokes and but one
+power stroke. The effect when two cylinders are employed
+is shown immediately below.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig026" id="Fig026"></a>
+<p class="leftlink"><a href="images/large087.png">Large<br />scale<br />image<br />(161 kB).</a></p>
+<img src="images/illo087.png" alt="Fig. 26" width="500" height="497" />
+<p class="caption">Fig. 26.&mdash;Diagrams Showing Duration of Events for a Four-Stroke Cycle,
+Six-Cylinder Engine.</p></div>
+
+<p><span class='pagenum'><a name="Page_92" id="Page_92">[92]</a></span>Here we have one explosion during the first half of the
+first revolution in one cylinder and another during the first
+half of the second revolution in the other cylinder. With
+a four-cylinder engine there is an explosion each half revolution,
+while in a six-cylinder engine there is one and one-half
+explosions during each half revolution. When six
+cylinders are used there is no lapse of time between power
+impulses, as these overlap and a continuous and smooth-turning
+movement is imparted to the crank shaft. The
+diagram shown at <a href="#Fig026">Fig. 26</a>, prepared by E. P. Pulley, can
+be studied to advantage in securing an idea of the coordination
+of effort that takes place in an engine of the six-cylinder
+type.</p>
+
+<p class='pagenum'><a name="Page_93" id="Page_93">[93]</a></p>
+
+<h3>ACTUAL DURATION OF DIFFERENT STROKES</h3>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig027" id="Fig027"></a>
+<img src="images/illo088.png" alt="Fig. 27" width="450" height="477" />
+<p class="caption">Fig. 27.&mdash;Diagram Showing Actual Duration of Different Strokes in Degrees.</p></div>
+
+<p>In the diagrams previously presented the writer has
+assumed, for the sake of simplicity, that each stroke takes
+place during half of one revolution of the crank-shaft,
+which corresponds to a crank-pin travel of one hundred
+and eighty degrees. The actual duration of these strokes
+is somewhat different. For example, the inlet stroke is
+usually a trifle more than a half revolution, and the exhaust
+is always considerably more. The diagram showing the
+comparative duration of the strokes is shown at <a href="#Fig027">Fig.
+27</a>.<span class='pagenum'><a name="Page_94" id="Page_94">[94]</a></span>
+The inlet valve opens ten degrees after the piston starts
+to go down and remains open thirty degrees after the
+piston has reached the bottom of its stroke. This means
+that the suction stroke corresponds to a crank-pin travel
+of two hundred degrees, while the compression stroke is
+measured by a movement of but one hundred and fifty
+degrees. It is common practice to open the exhaust valve
+before the piston reaches the end of the power stroke so
+that the actual duration of the power stroke is about one
+hundred and forty degrees, while the exhaust stroke corresponds
+to a crank-pin travel of two hundred and twenty-five
+degrees. In this diagram, which represents proper
+time for the valves to open and close, the dimensions in
+inches given are measured on the fly-wheel and apply only
+to a certain automobile motor. If the fly-wheel were
+smaller ten degrees would take up less than the dimensions
+given, while if the fly-wheel was larger a greater space on
+its circumference would represent the same crank-pin
+travel. Aviation engines are timed by using a timing disc
+attached to the crank-shaft as they are not provided with
+fly-wheels. Obviously, the distance measured in inches
+will depend upon the diameter of the disc, though the
+number of degrees interval would not change.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig028" id="Fig028"></a>
+<img src="images/illo089.png" alt="Fig. 28" width="600" height="180" />
+<p class="caption">Fig. 28.&mdash;Another Diagram to Facilitate Understanding Sequence of
+Functions in Six-Cylinder Engine.</p></div>
+
+<h3><a name="SecIV_6" id="SecIV_6"></a>EIGHT- AND TWELVE-CYLINDER V ENGINES</h3>
+
+<p>Those who have followed the development of the gasoline
+engine will recall the arguments that were made when
+the six-cylinder motor was introduced at a time that the<span class='pagenum'><a name="Page_95" id="Page_95">[95]</a></span>
+four-cylinder type was considered standard. The arrival
+of the eight-cylinder has created similar futile discussion
+of its practicability as this is so clearly established as to
+be accepted without question. It has been a standard
+power plant for aeroplanes for many years, early exponents
+having been the Antoinette, the Woolsley, the
+Renault, the E. N. V. in Europe and the Curtiss in the
+United States.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig029" id="Fig029"></a>
+<img src="images/illo090.png" alt="Fig. 29" width="500" height="316" />
+<p class="caption">Fig. 29.&mdash;Types of Eight-Cylinder Engines Showing the Advantage of the
+V Method of Cylinder Placing.</p></div>
+
+<p>The reason the V type shown at <a href="#Fig029">Fig. 29</a>, A is favored is
+that the &#8220;all-in-line form&#8221; which is shown at <a href="#Fig029">Fig. 29</a>, B is
+not practical for aircraft because of its length. Compared
+to the standard four-cylinder engine it is nearly twice as
+long and it required a much stronger and longer crank-shaft.
+It will be evident that it could not be located to
+advantage in the airplane fuselage. These undesirable
+factors are eliminated in the V type eight-cylinder motor,
+as it consists of two blocks of four cylinders each, so arranged
+that one set or block is at an angle of forty-five
+degrees from the vertical center line of the motor, or at
+an angle of ninety degrees with the other set. This
+arrangement of cylinders produces a motor that is no<span class='pagenum'><a name="Page_96" id="Page_96">[96]</a></span>
+longer than a four-cylinder engine of half the power
+would be.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig030" id="Fig030"></a>
+<img src="images/illo091.png" alt="Fig. 30" width="600" height="408" />
+<p class="caption">Fig. 30.&mdash;Curves Showing Torque of Various Engine Types Demonstrate
+Graphically Marked Advantage of the Eight-Cylinder Type.</p></div>
+
+<p>Apparently there is considerable misconception as to
+the advantage of the two extra cylinders of the eight as
+compared with the six-cylinder. It should be borne in mind
+that the multiplication in the number of cylinders noticed
+since the early days of automobile development has not
+been for solely increasing the power of the engine, but to
+secure a more even turning movement, greater flexibility
+and to eliminate destructive vibration. The ideal internal
+combustion motor, is the one having the most uniform turning
+movement with the least mechanical friction loss.
+Study of the torque outlines or plotted graphics shown
+at <a href="#Fig025">Figs. 25</a> and <a href="#Fig030">30</a> will show how multiplication of cylinders
+will produce steady power delivery due to overlapping
+impulses. The most practical form would be that which
+more nearly conforms to the steady running produced by
+a steam turbine or electric motor. The advocates of the
+eight-cylinder engine bring up the item of uniform torque<span class='pagenum'><a name="Page_97" id="Page_97">[97]</a></span>
+as one of the most important advantages of the eight-cylinder
+design. A number of torque diagrams are shown
+at <a href="#Fig030">Fig. 30</a>. While these appear to be deeply technical,
+they may be very easily followed when their purpose is
+explained. At the top is shown the torque diagram of a
+single-cylinder motor of the four-cycle type. The high
+point in the line represents the period of greatest torque
+or power generation, and it will be evident that this occurs
+early in the first revolution of the crank-shaft. Below this
+diagram is shown a similar curve except that it is produced
+by a four-cylinder engine. Inspection will show that
+the turning-moment is much more uniform than in the<span class='pagenum'><a name="Page_98" id="Page_98">[98]</a></span>
+single cylinder; similarly, the six-cylinder diagram is an
+improvement over the four, and the eight-cylinder diagram
+is an improvement over the six-cylinder.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig031" id="Fig031"></a>
+<img src="images/illo092.png" alt="Fig. 31" width="500" height="490" />
+<p class="caption">Fig. 31&mdash;Diagrams Showing How Increasing Number of Cylinders Makes
+for More Uniform Power Application.</p></div>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig032" id="Fig032"></a>
+<img src="images/illo094.png" alt="Fig. 32" width="600" height="372" />
+<p class="caption">Fig. 32.&mdash;How the Angle Between the Cylinders of an Eight- and Twelve-Cylinder V Motor Varies.</p></div>
+
+<p>The reason that practically continuous torque is obtained
+in an eight-cylinder engine is that one cylinder fires
+every ninety degrees of crank-shaft rotation, and as each
+impulse lasts nearly seventy-five per cent. of the stroke,
+one can easily appreciate that an engine that will give four
+explosions per revolution of the crank-shaft will run more
+uniformly than one that gives but three explosions per
+revolution, as the six-cylinder does, and will be twice as
+smooth running as a four-cylinder, in which but two explosions
+occur per revolution of the crank-shaft. The comparison
+is so clearly shown in graphical diagrams and in
+<a href="#Fig031">Fig. 31</a> that further description is unnecessary.</p>
+
+<p>Any eight-cylinder engine may be considered a &#8220;twin-four,&#8221;
+twelve-cylinder engines may be considered &#8220;twin
+sixes.&#8221;</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig033" id="Fig033"></a>
+<img src="images/illo095.jpg" alt="Fig. 33" width="500" height="429" />
+<p class="caption">Fig. 33.&mdash;The Hall-Scott Four-Cylinder 100 Horse-Power Aviation Motor.</p></div>
+
+<p class='pagenum'><a name="Page_101" id="Page_101">[101]</a></p>
+<div class="figcenter" style="width: 400px;"><a name="Fig034" id="Fig034"></a>
+<img src="images/illo096.jpg" alt="Fig. 34" width="400" height="639" />
+<p class="caption">Fig. 34.&mdash;Two Views of the Duesenberg Sixteen Valve Four-Cylinder
+Aviation Motor.</p></div>
+
+<p>The only points in which an eight-cylinder motor differs
+from a four-cylinder is in the arrangement of the
+connecting rod, as in many designs it is necessary to have
+two rods working from the same crank-pin. This difficulty
+is easily overcome in some designs by staggering the cylinders
+and having the two connecting rod big ends of conventional
+form side by side on a common crank-pin. In
+other designs one rod is a forked form and works on the
+outside of a rod of the regular pattern. Still another
+method is to have a boss just above the main bearing on
+one connecting rod to which the lower portion of the connecting
+rod in the opposite cylinder is hinged. As the
+eight-cylinder engine may actually be made lighter than
+the six-cylinder of equal power, it is possible to use smaller
+reciprocating parts, such as pistons, connecting rods and
+valve gear, and obtain higher engine speed with practically
+no vibration. The firing order in nearly every case is the
+same as in a four-cylinder except that the explosions occur
+alternately in each set of cylinders. The firing order of
+an eight-cylinder motor is apt to be confusing to the<span class='pagenum'><a name="Page_100"
+id="Page_100">[100]</a></span><span class='pagenum'><a name="Page_99" id="Page_99"></a></span>
+motorist, especially if one considers that there are eight
+possible sequences. The majority of engineers favor the
+alternate firing from side to side. Firing orders will be
+considered in proper sequence.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig035" id="Fig035"></a>
+<img src="images/illo097.jpg" alt="Fig. 35" width="500" height="369" />
+<p class="caption">Fig. 35.&mdash;The Hall-Scott Six-Cylinder Aviation Engine.</p></div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig036" id="Fig036"></a>
+<img src="images/illo098.jpg" alt="Fig. 36" width="500" height="545" />
+<p class="caption">Fig. 36.&mdash;The Curtiss Eight-Cylinder, 200 Horse-Power Aviation Engine.</p></div>
+
+<p>The demand of aircraft designers for more power has
+stimulated designers to work out twelve-cylinder motors.
+These are high-speed motors incorporating all recent features
+of design in securing light reciprocating parts, large
+valve openings, etc. The twelve-cylinder motor incorporates
+the best features of high-speed motor design and there
+is no need at this time to discuss further the pros and cons
+of the twelve-cylinder versus the eight or six, because it
+is conceded by all that there is the same degree of steady
+power application in the twelve over the eight as there
+would be in the eight over the six. The question resolves<span class='pagenum'><a name="Page_102" id="Page_102">[102]</a></span>
+itself into having a motor of high power that will run with
+minimum vibration and that produces smooth action. This
+is well shown by diagrams at <a href="#Fig031">Fig. 31</a>. It should be remembered
+that if an eight-cylinder engine will give four
+explosions per revolution of the fly-wheel, a twelve-cylinder
+type will give six explosions per revolution, and instead
+of the impulses coming 90 degrees crank travel apart, as
+in the case of the eight-cylinder, these will come but 60
+degrees of crank travel apart in the case of the twelve-cylinder.
+For this reason, the cylinders of a twelve are
+usually separated by 60 degrees while the eight has the
+blocks spaced 90 degrees apart. The comparison can be
+easily made by comparing the sectional views of Vee
+engines at <a href="#Fig032">Fig. 32</a>. When one realizes that the actual
+duration of the power stroke is considerably greater than
+120 degrees crank travel, it will be apparent that the
+overlapping of explosions must deliver a very uniform
+application of power. Vee engines have been devised<span class='pagenum'><a name="Page_103" id="Page_103">[103]</a></span>
+having the cylinders spaced but 45 degrees apart, but the
+explosions cannot be timed at equal intervals as when 90
+degrees separate the cylinder center lines.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig037" id="Fig037"></a>
+<img src="images/illo099.jpg" alt="Fig. 37" width="500" height="363" />
+<p class="caption">Fig. 37.&mdash;The Sturtevant Eight-Cylinder, High Speed Aviation Motor.</p></div>
+
+<h3><a name="SecIV_7" id="SecIV_7"></a>RADIAL CYLINDER ARRANGEMENTS</h3>
+
+<p>While the fixed cylinder forms of engines, having the
+cylinders in tandem in the four- and six-cylinder models
+as shown at <a href="#Fig033">Figs. 33</a> to <a href="#Fig035">35</a> inclusive and the eight-cylinder
+V types as outlined at <a href="#Fig036">Figs. 36</a> and <a href="#Fig037">37</a> have been generally
+used and are most in favor at the present time, other forms
+of motors having unconventional cylinder arrangements
+have been devised, though most of these are practically<span class='pagenum'><a name="Page_104" id="Page_104">[104]</a></span>
+obsolete. While many methods of decreasing weight and
+increasing mechanical efficiency of a motor are known to
+designers, one of the first to be applied to the construction
+of aeronautical power plants was an endeavor to group
+the components, which in themselves were not extremely
+light, into a form that would be considerably lighter than
+the conventional design. As an example, we may consider
+those multiple-cylinder forms in which the cylinders are
+disposed around a short crank-case, either radiating from
+a common center as at <a href="#Fig038">Fig. 38</a> or of the fan shape shown
+at <a href="#Fig039">Fig. 39</a>. This makes it possible to use a crank-case but
+slightly larger than that needed for one or two cylinders
+and it also permits of a corresponding decrease in length
+of the crank-shaft. The weight of the engine is lessened
+because of the reduction in crank-shaft and crank-case
+weight and the elimination of a number of intermediate
+bearings and their supporting webs which would be necessary
+with the usual tandem construction. While there are
+six power impulses to every two revolutions of the crank-shaft,<span class='pagenum'><a name="Page_105" id="Page_105">[105]</a></span>
+in the six-cylinder engine, they are not evenly spaced
+as is possible with the conventional arrangement.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig038" id="Fig038"></a>
+<img src="images/illo100.jpg" alt="Fig. 38" width="500" height="498" />
+<p class="caption">Fig. 38.&mdash;Anzani 40-50 Horse-Power Five-Cylinder Air Cooled Engine.</p></div>
+
+<p>In the Anzani form, which is shown at <a href="#Fig038">Fig. 38</a>, the crank-case
+is stationary and a revolving crank-shaft is employed
+as in conventional construction. The cylinders are five
+in number and the engine develops 40 to 50 H.P. with a
+weight of 72 kilograms or 158.4 lbs. The cylinders are of
+the usual air-cooled form having cooling flanges only part
+of the way down the cylinder. By using five cylinders it
+is possible to have the power impulses come regularly,
+they coming <span class="nowrap">145&deg;</span> crank-shaft travel apart, the crank-shaft
+making two turns to every five explosions. The balance
+is good and power output regular. The valves are<span class='pagenum'><a name="Page_106" id="Page_106">[106]</a></span>
+placed directly in the cylinder head and are operated by
+a common pushrod. Attention is directed to the novel
+method of installing the carburetor which supplies the mixture
+to the engine base from which inlet pipes radiate to
+the various cylinders. This engine is used on French
+school machines.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig039" id="Fig039"></a>
+<img src="images/illo101.jpg" alt="Fig. 39" width="500" height="360" />
+<p class="caption">Fig. 39.&mdash;Unconventional Six-Cylinder Aircraft Motor of Masson Design.</p></div>
+
+<p>In the form shown at <a href="#Fig039">Fig. 39</a> six cylinders are used,
+all being placed above the crank-shaft center line. This
+engine is also of the air-cooled form and develops 50 H. P.
+and weighs 105 kilograms, or 231 lbs. The carburetor is
+connected to a manifold casting attached to the engine base
+from which the induction pipes radiate to the various
+cylinders. The propeller design and size relative to the
+engine is clearly shown in this view. While flights have
+been made with both of the engines described, this method
+of construction is not generally followed and has been
+almost entirely displaced abroad by the revolving motors
+or by the more conventional eight-cylinder V engines.
+Both of the engines shown were designed about eight years<span class='pagenum'><a name="Page_107" id="Page_107">[107]</a></span>
+ago and would be entirely too small and weak for use in
+modern airplanes intended for active duty.</p>
+
+<h3><a name="SecIV_8" id="SecIV_8"></a>ROTARY ENGINES</h3>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig040" id="Fig040"></a>
+<img src="images/illo102.jpg" alt="Fig. 40" width="500" height="504" />
+<p class="caption">Fig. 40.&mdash;The Gnome Fourteen-Cylinder Revolving Motor.</p></div>
+
+<p>Rotary engines such as shown at <a href="#Fig040">Fig. 40</a> are generally
+associated with the idea of light construction and it is
+rather an interesting point that is often overlooked in
+connection with the application of this idea to flight
+motors, that the reason why rotary engines are popularly
+supposed to be lighter than the others is because they form
+their own fly-wheel, yet on aeroplanes, engines are seldom
+fitted with a fly-wheel at all. As a matter of fact the<span class='pagenum'><a name="Page_108" id="Page_108">[108]</a></span>
+Gnome engine is not so light because it is a rotary motor,
+and it is a rotary motor because the design that has
+been adopted as that most conducive to lightness is
+also most suited to an engine working in this way.
+The cylinders could be fixed and crank-shaft revolve
+without increasing the weight to any extent. There
+are two prime factors governing the lightness of an
+engine, one being the initial design, and the other the
+quality of the materials employed. The consideration
+of reducing weight by cutting away metal is a subsidiary
+method that ought not to play a part in standard
+practice, however useful it may be in special cases. In
+the Gnome rotary engine the lightness is entirely due to
+the initial design and to the materials employed in manufacture.
+Thus, in the first case, the engine is a radial
+engine, and has its seven or nine cylinders spaced equally
+around a crank-chamber that is no wider or rather longer
+than would be required for any one of the cylinders.
+This shortening of the crank-chamber not only effects
+a considerable saving of weight on its own account, but
+there is a corresponding saving in the shafts and other
+members, the dimensions of which are governed by the
+size of the crank-chamber. With regard to materials,
+nothing but steel is used throughout, and most of the metal
+is forged chrome nickel steel. The beautifully steady
+running of the engine is largely due to the fact that there
+are literally no reciprocating parts in the absolute sense,
+the apparent reciprocation between the pistons and cylinders
+being solely a relative reciprocation since both travel
+in circular paths, that of the pistons, however, being
+electric by one-half of the stroke length to that of the
+cylinder.</p>
+
+<p>While the Gnome engine has many advantages, on the
+other hand the head resistance offered by a motor of this
+type is considerable; there is a large waste of lubricating
+oil due to the centrifugal force which tends to throw the
+oil away from the cylinders; the gyroscopic effect of the
+rotary motor is detrimental to the best working of the<span class='pagenum'><a name="Page_109" id="Page_109">[109]</a></span>
+aeroplane, and moreover it requires about seven per cent.
+of the total power developed by the motor to drive the
+revolving cylinders around the shaft. Of necessity, the
+compression of this type of motor is rather low, and an
+additional disadvantage manifests itself in the fact that
+there is as yet no satisfactory way of muffling the rotary
+type of motor. The modern Gnome engine has been widely
+copied in various European countries, but its design was
+originated in America, the early Adams-Farwell engine
+being the pioneer form. It has been made in seven- and
+nine-cylinder types and forms of double these numbers.
+The engine illustrated at <a href="#Fig040">Fig. 40</a> is a fourteen-cylinder
+form. The simple engines have an odd number of cylinders
+in order to secure evenly spaced explosions. In the
+seven-cylinder, the impulses come <span class="nowrap">102.8&deg;</span> apart. In the
+nine-cylinder form, the power strokes are spaced <span class="nowrap">80&deg;</span> apart.
+The fourteen-cylinder engine is virtually two seven-cylinder
+types mounted together, the cranks being just the
+same as in a double cylinder opposed motor, the explosions
+coming <span class="nowrap">51.4&deg;</span> apart; while in the eighteen-cylinder model
+the power impulses come every <span class="nowrap">40&deg;</span> cylinder travel. Other
+rotary motors have been devised, such as the Le Rhone
+and the Clerget in France and several German copies of
+these various types. The mechanical features of these
+motors will be fully considered <a href="#ChXII">later</a>.</p>
+
+<hr class="c25" />
+<p class='pagenum'><a name="Page_110" id="Page_110">[110]</a></p>
+<h2><a name="ChV" id="ChV"></a>CHAPTER V</h2>
+
+<div class="chapsec"><p><a href="#SecV_1">Properties of Liquid Fuels</a>&mdash;<a href="#SecV_2">Distillates of Crude
+Petroleum</a>&mdash;<a href="#SecV_3">Principles of Carburetion Outlined</a>&mdash;<a href="#SecV_4">Air Needed to Burn
+Gasoline</a>&mdash;<a href="#SecV_5">What a Carburetor Should Do</a>&mdash;<a href="#SecV_6">Liquid Fuel Storage and Supply</a>&mdash;<a
+href="#SecV_7">Vacuum Fuel Feed</a>&mdash;<a href="#SecV_8">Early Vaporizer Forms</a>&mdash;<a href="#SecV_9">Development of Float Feed
+Carburetor</a>&mdash;<a href="#SecV_10">Maybach&#8217;s Early Design</a>&mdash;<a href="#SecV_11">Concentric Float and Jet Type</a>&mdash;<a
+href="#SecV_12">Schebler Carburetor</a>&mdash;<a href="#SecV_13">Claudel Carburetor</a>&mdash;<a href="#SecV_14">Stewart Metering Pin
+Type</a>&mdash;<a href="#SecV_15">Multiple Nozzle Vaporizers</a>&mdash;<a href="#SecV_16">Two-Stage Carburetor</a>&mdash;<a
+href="#SecV_17">Master Multiple Jet Type</a>&mdash;<a href="#SecV_18">Compound Nozzle Zenith Carburetor</a>&mdash;<a href="#SecV_19">Utility
+of Gasoline Strainers</a>&mdash;<a href="#SecV_20">Intake Manifold Design and Construction</a>&mdash;<a href="#SecV_21">Compensating for
+Various Atmospheric Conditions</a>&mdash;<a href="#SecV_22">How High Altitude Affects Power</a>&mdash;<a href="#SecV_23">The Diesel
+System</a>&mdash;<a href="#SecV_24">Notes on Carburetor Installation</a>&mdash;<a href="#SecV_25">Notes on Carburetor
+Adjustment</a>.</p></div>
+
+<p><a name="SecV_1" id="SecV_1"></a>There is no appliance that has more material value
+upon the efficiency of the internal combustion motor than
+the carburetor or vaporizer which supplies the explosive
+gas to the cylinders. It is only in recent years that engineers
+have realized the importance of using carburetors
+that are efficient and that are so strongly and simply made
+that there will be little liability of derangement. As the
+power obtained from the gas-engine depends upon the
+combustion of fuel in the cylinders, it is evident that if
+the gas supplied does not have the proper proportions of
+elements to insure rapid combustion the efficiency of the
+engine will be low. When a gas engine is used as a stationary
+installation it is possible to use ordinary illuminating
+or natural gas for fuel, but when this prime mover is
+applied to automobiles or airplanes it is evident that considerable
+difficulty would be experienced in carrying enough
+compressed coal gas to supply the engine for even a very
+short trip. Fortunately, the development of the internal-combustion
+motor was not delayed by the lack of suitable
+fuel.</p>
+
+<p>Engineers were familiar with the properties of certain<span class='pagenum'><a name="Page_111" id="Page_111">[111]</a></span>
+liquids which gave off vapors that could be mixed with air
+to form an explosive gas which burned very well in the
+engine cylinders. A very small quantity of such liquids
+would suffice for a very satisfactory period of operation.
+The problem to be solved before these liquids could be
+applied in a practical manner was to evolve suitable apparatus
+for vaporizing them without waste. Among the
+liquids that can be combined with air and burned, gasoline
+is the most volatile and is the fuel utilized by internal-combustion
+engines.</p>
+
+<p>The widely increasing scope of usefulness of the internal-combustion
+motor has made it imperative that other
+fuels be applied in some instances because the supply of
+gasoline may in time become inadequate to supply the
+demand. In fact, abroad this fuel sells for fifty to two
+hundred per cent. more than it does in America because
+most of the gasoline used must be imported from this
+country or Russia. Because of this foreign engineers have
+experimented widely with other substances, such as alcohol,
+benzol, and kerosene, but more to determine if they
+can be used to advantage in motor cars than in airplane
+engines.</p>
+
+<h3><a name="SecV_2" id="SecV_2"></a>DISTILLATES OF CRUDE PETROLEUM</h3>
+
+<p>Crude petroleum is found in small quantities in almost
+all parts of the world, but a large portion of that produced
+commercially is derived from American wells. The
+petroleum obtained in this country yields more of the
+volatile products than those of foreign production, and for
+that reason the demand for it is greater. The oil fields
+of this country are found in Pennsylvania, Indiana, and
+Ohio, and the crude petroleum is usually in association
+with natural gas. This mineral oil is an agent from which
+many compounds and products are derived, and the products
+will vary from heavy sludges, such as asphalt, to
+the lighter and more volatile components, some of which
+will evaporate very easily at ordinary temperatures.</p>
+
+<p>The compounds derived from crude petroleum are composed<span class='pagenum'><a name="Page_112" id="Page_112">[112]</a></span>
+principally of hydrogen and carbon and are termed
+&#8220;Hydrocarbons.&#8221; In the crude product one finds many
+impurities, such as free carbon, sulphur, and various
+earthy elements. Before the oil can be utilized it must be
+subjected to a process of purifying which is known as
+refining, and it is during this process, which is one of
+destructive distillation, that the various liquids are separated.
+The oil was formerly broken up into three main
+groups of products as follows: Highly volatile, naphtha,
+benzine, gasoline, eight to ten per cent. Light oils, such
+as kerosene and light lubricating oils seventy to eighty
+per cent. Heavy oils or residuum five to nine per cent.
+From the foregoing it will be seen that the available supply
+of gasoline is determined largely by the demand existing
+for the light oils forming the larger part of the
+products derived from crude petroleum. New processes
+have been recently discovered by which the lighter oils,
+such as kerosene, are reduced in proportion and that of
+gasoline increased, though the resulting liquid is neither
+the high grade, volatile gasoline known in the early days
+of motoring nor the low grade kerosene.</p>
+
+<h3><a name="SecV_3" id="SecV_3"></a>PRINCIPLES OF CARBURETION OUTLINED</h3>
+
+<p>The process of carburetion is combining the volatile
+vapors which evaporate from the hydrocarbon liquids with
+certain proportions of air to form an inflammable gas.
+The quantities of air needed vary with different liquids
+and some mixtures burn quicker than do other combinations
+of air and vapor. Combustion is simply burning and
+it may be rapid, moderate or slow. Mixtures of gasoline
+and air burn quickly, in fact the combustion is so rapid
+that it is almost instantaneous and we obtain what is
+commonly termed an &#8220;explosion.&#8221; Therefore the explosion
+of gas in the automobile engine cylinder which
+produces the power is really a combination of chemical
+elements which produce heat and an increase in the volume
+of the gas because of the increase in temperature.</p>
+
+<p>If the gasoline mixture is not properly proportioned<span class='pagenum'><a name="Page_113" id="Page_113">[113]</a></span>
+the rate of burning will vary, and if the mixture is either
+too rich or too weak the power of the explosion is reduced
+and the amount of power applied to the piston is decreased
+proportionately. In determining the proper proportions
+of gasoline and air, one must take the chemical
+composition of gasoline into account. The ordinary liquid
+used for fuel is said to contain about eight-four per cent.
+carbon and sixteen per cent. hydrogen. Air is composed
+of oxygen and nitrogen and the former has a great affinity,
+or combining power, with the two constituents of hydro-carbon
+liquids. Therefore, what we call an explosion is
+merely an indication that oxygen in the air has combined
+with the carbon and hydrogen of the gasoline.</p>
+
+<h3><a name="SecV_4" id="SecV_4"></a>AIR NEEDED TO BURN GASOLINE</h3>
+
+<p>In figuring the proper volume of air to mix with a
+given quantity of fuel, one takes into account the fact that
+one pound of hydrogen requires eight pounds of oxygen
+to burn it, and one pound of carbon needs two and one-third
+pounds of oxygen to insure its combustion. Air is
+composed of one part of oxygen to three and one-half portions
+of nitrogen by weight. Therefore for each pound of
+oxygen one needs to burn hydrogen or carbon four and
+one-half pounds of air must be allowed. To insure combustion
+of one pound of gasoline which is composed of
+hydrogen and carbon we must furnish about ten pounds
+of air to burn the carbon and about six pounds of air to
+insure combustion of hydrogen, the other component of
+gasoline. This means that to burn one pound of gasoline
+one must provide about sixteen pounds of air.</p>
+
+<p>While one does not usually consider air as having much
+weight, at a temperature of sixty-two degrees Fahrenheit
+about fourteen cubic feet of air will weigh a pound, and
+to burn a pound of gasoline one would require about two
+hundred cubic feet of air. This amount will provide for
+combustion theoretically, but it is common practice to
+allow twice this amount because the element nitrogen,
+which is the main constituent of air, is an inert gas and<span class='pagenum'><a name="Page_114" id="Page_114">[114]</a></span>
+instead of aiding combustion it acts as a deterrent of
+burning. In order to be explosive, gasoline vapor must
+be combined with definite quantities of air. Mixtures that
+are rich in gasoline ignite quicker than those which have
+more air, but these are only suitable when starting or
+when running slowly, as a rich mixture ignites much
+quicker than a weak mixture. The richer mixture of
+gasoline and air not only burns quicker but produces the
+most heat and the most effective pressure in pounds per
+square inch of piston top area.</p>
+
+<p>The amount of compression of the charge before ignition
+also has material bearing on the force of the explosion.
+The higher the degree of compression the greater
+the force exerted by the rapid combustion of the gas. It
+may be stated that as a general thing the maximum explosive
+pressure is somewhat more than four times the
+compression pressure prior to ignition. A charge compressed
+to sixty pounds will have a maximum of approximately
+two hundred and forty pounds; compacted to
+eighty pounds it will produce a pressure of about three
+hundred pounds on each square inch of piston area at
+the beginning of the power stroke. Mixtures varying
+from one part of gasoline vapor to four of air to others
+having one part of gasoline vapor to thirteen of air can
+be ignited, but the best results are obtained when the
+proportions are one to five or one to seven, as this mixture
+is said to be the one that will produce the highest
+temperature, the quickest explosion, and the most
+pressure.</p>
+
+<h3><a name="SecV_5" id="SecV_5"></a>WHAT A CARBURETOR SHOULD DO</h3>
+
+<p>While it is apparent that the chief function of a carbureting
+device is to mix hydrocarbon vapors with air to
+secure mixtures that will burn, there are a number of factors
+which must be considered before describing the principles
+of vaporizing devices. Almost any device which
+permits a current of air to pass over or through a volatile
+liquid will produce a gas which will explode when<span class='pagenum'><a
+name="Page_116" id="Page_116">[116]</a></span><span class='pagenum'><a name="Page_115" id="Page_115">[115]</a></span>
+compressed and ignited in the motor cylinder. Modern
+carburetors are not only called upon to supply certain
+quantities of gas, but these must deliver a mixture to the
+cylinders that is accurately proportioned and which will
+be of proper composition at all engine speeds.</p>
+
+<p>Flexible control of the engine is sought by varying the
+engine speed by regulating the supply of gas to the cylinders.
+The power plant should run from its lowest to its
+highest speed without any irregularity in torque, i.e., the
+acceleration should be gradual rather than spasmodic. As
+the degree of compression will vary in value with the
+amount of throttle opening, the conditions necessary to
+obtain maximum power differ with varying engine speeds.
+When the throttle is barely opened the engine speed is
+low and the gas must be richer in fuel than when the
+throttle is wide open and the engine speed high.</p>
+
+<p>When an engine is turning over slowly the compression
+has low value and the conditions are not so favorable to
+rapid combustion as when the compression is high. At
+high engine speeds the gas velocity through the intake
+piping is higher than at low speeds, and regular engine
+action is not so apt to be disturbed by condensation of
+liquid fuel in the manifold due to excessively rich mixture
+or a superabundance of liquid in the stream of carbureted
+air.</p>
+
+<h3><a name="SecV_6" id="SecV_6"></a>LIQUID FUEL STORAGE AND SUPPLY</h3>
+
+<p>The problem of gasoline storage and method of supplying
+the carburetor is one that is determined solely by
+design of the airplane. While the object of designers
+should be to supply the fuel to the carburetor by as simple
+means as possible the fuel supply system of some airplanes
+is quite complex. The first point to consider is the location
+of the gasoline tank. This depends upon the amount
+of fuel needed and the space available in the fuselage.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig041" id="Fig041"></a>
+<p class="leftlink"><a href="images/large110.jpg">Large<br />image<br />(193 kB).</a></p>
+<img src="images/illo110.jpg" alt="Fig. 41" width="500" height="298" />
+<p class="caption">Fig. 41.&mdash;How Gravity Feed Fuel Tank May Be Mounted Back of Engine and Secure Short Fuel Line.</p></div>
+
+<p>A very simple and compact fuel supply system is shown
+at <a href="#Fig041">Fig. 41</a>. In this instance the fuel container is placed
+immediately back of the engine cylinder. The carburetor<span class='pagenum'><a name="Page_117" id="Page_117">[117]</a></span>
+which is carried as indicated is joined to the tank by a
+short piece of copper or flexible rubber tubing. This is
+the simplest possible form of fuel supply system and one
+used on a number of excellent airplanes.</p>
+
+<p>As the sizes of engines increase and the power plant
+fuel consumption augments it is necessary to use more
+fuel, and to obtain a satisfactory flying radius without
+frequent landings for filling the fuel tank it is necessary
+to supply large containers.</p>
+
+<p>When a very powerful power plant is fitted, as on
+battle planes of high capacity, it is necessary to carry
+large quantities of gasoline. In order to use a tank of
+sufficiently large capacity it may be necessary to carry it
+lower than the carburetor. When installed in this manner
+it is necessary to force fuel out of the tank by air pressure
+or to pump it with a vacuum tank because the gasoline
+tank is lower than the carburetor it supplies and the gasoline
+cannot flow by gravity as in the simpler systems.
+While the pressure and gravity feed systems are generally
+used in airplanes, it may be well to describe the vacuum
+lift system which has been widely applied to motor cars
+and which may have some use in connection with airplanes
+as these machines are developed.</p>
+
+<h3><a name="SecV_7" id="SecV_7"></a>STEWART VACUUM FUEL FEED</h3>
+
+<p>One of the marked tendencies has been the adoption
+of a vacuum fuel feed system to draw the gasoline from
+tanks placed lower than the carburetor instead of using
+either exhaust gas or air pressure to achieve this end. The
+device generally fitted is the Stewart vacuum feed tank
+which is clearly shown in section at <a href="#Fig042">Fig. 42</a>. In this system
+the suction of a motor is employed to draw gasoline
+from the main fuel tank to the auxiliary tank incorporated
+in the device and from this tank the liquid flows to the
+carburetor. It is claimed that all the advantages of the
+pressure system are obtained with very little more complication
+than is found on the ordinary gravity feed. The
+mechanism is all contained in the cylindrical tank shown,<span class='pagenum'><a name="Page_118" id="Page_118">[118]</a></span>
+which may be mounted either on the front of the dash or
+on the side of the engine as shown.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig042" id="Fig042"></a>
+<img src="images/illo113.png" alt="Fig. 42" width="450" height="501" />
+<p class="caption">Fig. 42.&mdash;The Stewart Vacuum Fuel Feed Tank.</p></div>
+
+<p>The tank is divided into two chambers, the upper one
+being the filling chamber and the lower one the emptying
+chamber. The former, which is at the top of the device,
+contains the float valve, as well as the pipes running to
+the main fuel container and to the intake manifold. The
+lower chamber is used to supply the carburetor with gasoline
+and is under atmospheric pressure at all times, so the
+flow of fuel from it is by means of gravity only. Since<span class='pagenum'><a name="Page_119" id="Page_119">[119]</a></span>
+this chamber is located somewhat above the carburetor,
+there must always be free flow of fuel. Atmospheric pressure
+is maintained by the pipes A and B, the latter opening
+into the air. In order that the fuel will be sucked
+from a main tank to the upper chamber, the suction valve
+must be opened and the atmospheric valve closed. Under
+these conditions the float is at the bottom and the suction
+at the intake manifold produces a vacuum in the tank
+which draws the gasoline from the main tank to the upper
+chamber. When the upper chamber is filled at the proper
+height the float rises to the top, this closing the suction
+valve and opening the atmospheric valve. As the suction
+is now cut off, the lower chamber is filled by gravity owing
+to there being atmospheric pressure in both upper and
+lower chambers. A flap valve is provided between the
+two chambers to prevent the gasoline in the lower one
+from being sucked back into the upper one. The atmospheric
+and suction valves are controlled by the levers C
+and D, both of which are pivoted at E, their outer ends
+being connected by two coil springs. It is seen that the
+arrangement of these two springs is such that the float
+must be held at the extremity of its movement, and that
+it cannot assume an intermediate position.</p>
+
+<p>This intermittent action is required to insure that the
+upper part of the tank may be under atmospheric pressure
+part of the time for the gasoline to flow to the lower chamber.
+When the level of gasoline drops to a certain point,
+the float falls, thus opening the suction valve and closing
+the atmospheric valve. The suction of the motor then
+causes a flow of fuel from the main container. As soon
+as the level rises to the proper height the float returns to
+its upper position. It takes about two seconds for the
+chamber to become full enough to raise the float, as but
+.05 gallon is transferred at a time. The pipe running from
+the bottom of the lower chamber to the carburetor extends
+up a ways, so that there is but little chance of dirt or water
+being carried to the float chamber.</p>
+
+<p>If the engine is allowed to stand long enough so that the<span class='pagenum'><a name="Page_120" id="Page_120">[120]</a></span>
+tank becomes empty, it will be replenished after the motor
+has been cranked over four or five times with the throttle
+closed. The installation of the Stewart Vacuum-Gravity
+System is very simple. The suction pipe is tapped into
+the manifold at a point as near the cylinders as possible,
+while the fuel pipe is inserted into the gasoline tank and
+runs to the bottom of that member. There is a screen at
+the end of the fuel pipe to prevent any trouble due to deposits
+of sediment in the main container. As the fuel is
+sucked from the gasoline tank a small vent must be made
+in the tank filler cap so that the pressure in the main tank
+will always be that of the atmosphere.</p>
+
+<h3><a name="SecV_8" id="SecV_8"></a>EARLY VAPORIZER FORMS</h3>
+
+<p>The early types of carbureting devices were very crude
+and cumbersome, and the mixture of gasoline vapor and
+air was accomplished in three ways. The air stream was
+passed over the surface of the liquid itself, through loosely
+placed absorbent material saturated with liquid, or directly
+through the fuel. The first type is known as the surface
+carburetor and is now practically obsolete. The second
+form is called the &#8220;wick&#8221; carburetor because the air
+stream was passed over or through saturated wicking. The
+third form was known as a &#8220;bubbling&#8221; carburetor. While
+these primitive forms gave fairly good results with the
+early slow-speed engines and the high grade, or very
+volatile, gasoline which was first used for fuel, they would
+be entirely unsuitable for present forms of engines because
+they would not carburate the lower grades of gasoline
+which are used to-day, and would not supply the
+modern high-speed engines with gas of the proper consistency
+fast enough even if they did not have to use very
+volatile gasoline. The form of carburetor used at the
+present time operates on a different principle. These
+devices are known as &#8220;spraying carburetors.&#8221; The fuel
+is reduced to a spray by the suction effect of the entering
+air stream drawing it through a fine opening.</p>
+
+<p>The advantage of this construction is that a more<span class='pagenum'><a name="Page_121" id="Page_121">[121]</a></span>
+thorough amalgamation of the gasoline and air particles
+is obtained. With the earlier types previously considered
+the air would combine with only the more volatile elements,
+leaving the heavier constituents in the tank. As the fuel
+became stale it was difficult to vaporize it, and it had to
+be drained off and fresh fuel provided before the proper
+mixture would be produced. It will be evident that when
+the fuel is sprayed into the air stream, all the fuel will be
+used up and the heavier portions of the gasoline will be
+taken into the cylinder and vaporized just as well as the
+more volatile vapors.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig043" id="Fig043"></a>
+<img src="images/illo116.png" alt="Fig. 43" width="450" height="424" />
+<p class="caption">Fig. 43.&mdash;Marine-Type Mixing Valve, by which Gasoline is Sprayed into Air
+Stream Through Small Opening in Air-Valve Seat.</p></div>
+
+<p>The simplest form of spray carburetor is that shown
+at <a href="#Fig043">Fig. 43</a>. In this the gasoline opening through
+which<span class='pagenum'><a name="Page_122" id="Page_122">[122]</a></span>
+the fuel is sprayed into the entering air stream is closed
+by the spring-controlled mushroom valve which regulates
+the main air opening as well. When the engine draws in
+a charge of air it unseats the valve and at the same time
+the air flowing around it is saturated with gasoline particles
+through the gasoline opening. The mixture thus
+formed goes to the engine through the mixture passage.
+Two methods of varying the fuel proportions are provided.
+One of these consists of a needle valve to regulate the
+amount of gasoline, the other is a knurled screw which
+controls the amount of air by limiting the lift of the
+jump valve.</p>
+
+<h3><a name="SecV_9" id="SecV_9"></a>DEVELOPMENT OF FLOAT-FEED CARBURETOR</h3>
+
+<p>The modern form of spraying carburetor is provided
+with two chambers, one a mixing chamber through which
+the air stream passes and mixes with a gasoline spray,
+the other a float chamber in which a constant level of fuel
+is maintained by simple mechanism. A jet or standpipe
+is used in the mixing chamber to spray the fuel through
+and the object of the float is to maintain the fuel level
+to such a point that it will not overflow the jet when the
+motor is not drawing in a charge of gas. With the simple
+forms of generator valve in which the gasoline opening is
+controlled by the air valve, a leak anywhere in either
+valve or valve seat will allow the gasoline to flow continuously
+whether the engine is drawing in a charge or not.
+The liquid fuel collects around the air opening, and when
+the engine inspires a charge it is saturated with gasoline
+globules and is excessively rich. With a float-feed construction,
+which maintains a constant level of gasoline at
+the right height in the standpipe, liquid fuel will only be
+supplied when drawn out of the jet by the suction effect
+of the entering air stream.</p>
+
+<h3><a name="SecV_10" id="SecV_10"></a>MAYBACH&#8217;S EARLY DESIGN</h3>
+
+<p>The first form of spraying carburetor ever applied
+successfully was evolved by Maybach for use on one of the<span
+class='pagenum'><a name="Page_124" id="Page_124">[124]</a></span><span class='pagenum'><a name="Page_123" id="Page_123"></a></span>
+earliest Daimler engines. The general principles of operation
+of this pioneer float-feed carburetor are shown at
+<a href="#Fig044">Fig. 44</a>, A. The mixing chamber and valve chamber were
+one and the standpipe or jet protruded into the mixing
+chamber. It was connected to the float compartment by a
+pipe. The fuel from the tank entered the top of the float
+compartment and the opening was closed by a needle
+valve carried on top of a hollow metal float. When the
+level of gasoline in the float chamber was lowered the
+float would fall and the needle valve uncover the opening.
+This would permit the gasoline from the tank to flow into
+the float chamber, and as the chamber filled the float would
+rise until the proper level had been reached, under which
+conditions the float would shut off the gasoline opening.
+On every suction stroke of the engine the inlet valve, which
+was an automatic type, would leave its seat and a stream
+of air would be drawn through the air opening and around
+the standpipe or jet. This would cause the gasoline to
+spray out of the tube and mix with the entering air stream.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig044" id="Fig044"></a>
+<p class="leftlink"><a href="images/large118.png">Large<br />image<br />(101 kB).</a></p>
+<img src="images/illo118.png" alt="Fig. 44" width="500" height="312" />
+<p class="caption">Fig. 44.&mdash;Tracing Evolution of Modern Spray Carburetor. A&mdash;Early Form Evolved by Maybach.
+B.&mdash;Ph&oelig;nix-Daimler Modification of Maybach&#8217;s Principle. C&mdash;Modern Concentric Float Automatic Compensating
+Carburetor.</p></div>
+
+<p>The form shown at <a href="#Fig044">B</a> was a modification of Maybach&#8217;s
+simple device and was first used on the Ph&oelig;nix-Daimler
+engines. Several improvements are noted in this device.
+First, the carburetor was made one unit by casting the
+float and mixing chambers together instead of making them
+separate and joining them by a pipe, as shown at <a href="#Fig044">A</a>. The
+float construction was improved and the gasoline shut-off
+valve was operated through leverage instead of being directly
+fastened to the float. The spray nozzle was surrounded
+by a choke tube which concentrated the air stream
+around it and made for more rapid air flow at low engine
+speeds. A conical piece was placed over the jet to break
+up the entering spray into a mist and insure more intimate
+admixture of air and gasoline. The air opening was
+provided with an air cone which had a shutter controlling
+the opening so that the amount of air entering could be
+regulated and thus vary the mixture proportions within
+certain limits.</p>
+
+<p class='pagenum'><a name="Page_125" id="Page_125">[125]</a></p>
+
+<h3><a name="SecV_11" id="SecV_11"></a>CONCENTRIC FLOAT AND JET TYPE</h3>
+
+<p>The form shown at <a href="#Fig044">B</a> has been further improved, and
+the type shown at <a href="#Fig044">C</a> is representative of modern single
+jet practice. In this the float chamber and mixing chamber
+are concentric. A balanced float mechanism which insures
+steadiness of feed is used, the gasoline jet or standpipe
+is provided with a needle valve to vary the amount of
+gasoline supplied the mixture and two air openings are
+provided. The main air port is at the bottom of the
+vaporizer, while an auxiliary air inlet is provided at the
+side of the mixing chamber. There are two methods of
+controlling the mixture proportions in this form of carburetor.
+One may regulate the gasoline needle or adjust
+the auxiliary air valve.</p>
+
+<h3><a name="SecV_12" id="SecV_12"></a>SCHEBLER CARBURETOR</h3>
+
+<p>A Schebler carburetor, which has been used on some
+airplane engines, is shown in <a href="#Fig045">Fig. 45</a>. It will be noticed
+that a metering pin or needle valve opens the jet when
+the air valve opens. The long arm of a leverage is connected
+to the air valve, while the short arm is connected
+to the needle, the reduction in leverage being such that
+the needle valve is made to travel much less than the air
+valve. For setting the amount of fuel passed or the size
+of the jet orifice when running with the air valve closed,
+there is a screw which raises or lowers the fulcrum of
+the lever and there is also a dash control having the same
+effect by pushing down the fulcrum against a small spring.
+A long extension is given to the venturi tube which is very
+narrow around the jet orifices, which are horizontal and
+shown at A in the drawing. Fuel enters the float chamber
+through the union M, and the spring P holds the metering
+pin upward against the restraining action of the lever.
+The air valve may be set by an easily adjustable knurled
+screw shown in the drawing, and fluttering of the valve is
+prevented by the piston dash pot carried in a chamber
+above the valve into which the valve stem projects. The<span
+class='pagenum'><a name="Page_127" id="Page_127">[127]</a></span><span class='pagenum'><a name="Page_126" id="Page_126"></a></span>
+primary air enters beneath the jet passage and there is
+a small throttle in the intake to increase the speed of air
+flow for starting purposes. The carburetor is adapted for
+the use of a hot-air connection to the stove around the
+exhaust pipe and it is recommended that such a fitting be
+supplied. The lever which controls the supply of air
+through the primary air intake is so arranged that if
+desired it can be connected with a linkage on the dash
+or control column by means of a flexible wire.</p>
+
+<div class="figcenter" style="width: 550px;"><a name="Fig045" id="Fig045"></a>
+<img src="images/illo121.png" alt="Fig. 45" width="550" height="372" />
+<p class="caption">Fig. 45.&mdash;New Model of Schebler Carburetor With Metering Valve and Extended Venturi. Note Mechanical
+Connection Between Air Valve and Fuel Regulating Needle.</p></div>
+
+<h3><a name="SecV_13" id="SecV_13"></a>THE CLAUDEL (FRENCH) CARBURETOR</h3>
+
+<p>This carburetor is of extremely simple construction,
+because it has no supplementary or auxiliary air valve
+and no moving parts except the throttle controlling the
+gas flow. The construction is already shown in <a href="#Fig046">Fig. 46</a>.<span
+class='pagenum'><a name="Page_128" id="Page_128">[128]</a></span>
+The spray jet is eccentric with a surrounding sleeve or
+tube in which there are two series of small orifices, one
+at the top and the other near the bottom. The former
+are about level with the spray jet opening. The sleeve
+surrounding the nozzle is closed at the top. The air,
+passing the upper holes in the sleeve, produces a vacuum
+in the sleeve, thereby drawing air in through the bottom
+holes. It is this moving interior column of air that controls
+the flow of gasoline from the nozzle. Owing to the
+friction of the small passages, the speed of air flow through
+the sleeve does not increase as fast as the speed of air
+flow outside the sleeve, hence there is a tendency for the
+mixture to remain constant. The throttle of this carburetor
+is of the barrel type, and the top of the spray nozzle
+and its surrounding sleeve are located inside the throttle.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig046" id="Fig046"></a>
+<img src="images/illo122.png" alt="Fig. 46" width="450" height="401" />
+<p class="caption">Fig. 46.&mdash;The Claudel Carburetor.</p></div>
+
+<h3><a name="SecV_14" id="SecV_14"></a>STEWART METERING PIN CARBURETOR</h3>
+
+<p>The carburetor shown at <a href="#Fig047">Fig. 47</a> is a metering type in
+which the vacuum at the jet is controlled by the weight
+of the metering valve surrounding the upright metering
+pin. The only moving part is the metering valve, which
+rises and falls with the changes in vacuum. The air
+chamber surrounds the metering valve, and there is a mixing
+chamber above. As the valve is drawn up the gasoline
+passage is enlarged on account of the predetermined taper
+on the metering pin, and the air passage also is increased
+proportionately, giving the correct mixture. A dashpot
+at the bottom of the valve checks flutter. In idling the
+valve rests on its seat, practically closing the air and giving
+the necessary idling mixture. A passage through the
+valve acts as an aspirating tube. When the valve is closed
+altogether the primary air passes through ducts in the
+valve itself, giving the proper amount for idling. The
+one adjustment consists in raising or lowering the tapered
+metering pin, increasing or decreasing the supply of
+gasoline. Dash control is supplied. This pulls down the
+metering pin, increasing the gasoline flow. The duplex
+type for eight- and twelve-cylinder motors is the same in<span class='pagenum'><a name="Page_129" id="Page_129">[129]</a></span>
+principle as model 25, but it is a double carburetor synchronized
+as to throttle movements, adjustments, etc. The
+duplex for aeronautical motors is made of cast aluminum
+alloy.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig047" id="Fig047"></a>
+<img src="images/illo124.png" alt="Fig. 47" width="500" height="571" />
+<p class="caption">Fig. 47.&mdash;The Stewart Metering Pin Carburetor.</p></div>
+
+<h3><a name="SecV_15" id="SecV_15"></a>MULTIPLE NOZZLE VAPORIZERS</h3>
+
+<p>To secure properly proportioned mixtures some carburetor
+designers have evolved forms in which two or
+more nozzles are used in a common mixing chamber. The
+usual construction is to use two, one having a small opening
+and placed in a small air tube and used only for low<span class='pagenum'><a name="Page_130" id="Page_130">[130]</a></span>
+speeds, the other being placed in a larger air tube and
+having a slightly augmented bore so that it is employed
+on intermediate speeds. At high speeds both jets would
+be used in series. Some multiple jet carburetors could
+be considered as a series of these instruments, each one
+being designed for certain conditions of engine action.
+They would vary from small size just sufficient to run
+the engine at low speed to others having sufficient capacity
+to furnish gas for the highest possible engine speed when
+used in conjunction with the smaller members which have
+been brought into service progressively as the engine speed
+has been augmented. The multiple nozzle carburetor differs
+from that in which a single spray tube is used only
+in the construction of the mixing chamber, as a common
+float bowl can be used to supply all spray pipes. It is
+common practice to bring the jets into action progressively
+by some form of mechanical connection with the
+throttle or by automatic valves.</p>
+
+<p>The object of any multiple nozzle carburetor is to
+secure greater flexibility and endeavor to supply mixtures
+of proper proportions at all speeds of the engine.
+It should be stated, however, that while devices of this
+nature lend themselves readily to practical application it
+is more difficult to adjust them than the simpler forms
+having but one nozzle. When a number of jets are used
+the liability of clogging up the carburetor is increased,
+and if one or more of the nozzles is choked by a particle
+of dirt or water the resulting mixture trouble is difficult
+to detect. One of the nozzles may supply enough gasoline
+to permit the engine to run well at certain speeds and yet
+not be adequate to supply the proper amount of gas under
+other conditions. In adjusting a multiple jet carburetor
+in which the jets are provided with gasoline regulating
+needles, it is customary to consider each nozzle as a distinct
+carburetor and to regulate it to secure the best motor
+action at that throttle position which corresponds to the
+conditions under which the jet is brought into service.
+For instance, that supplied the primary mixing chamber<span class='pagenum'><a name="Page_131" id="Page_131">[131]</a></span>
+should be regulated with the throttle partly closed, while
+the auxiliary jet should be adjusted with the throttle fully
+opened.</p>
+
+<h3><a name="SecV_16" id="SecV_16"></a>BALL AND BALL TWO-STAGE CARBURETOR</h3>
+
+<p>This is a two-stage vaporizing device, hot air being
+used in the primary or initial stage of vaporization and
+cold air in the supplementary stage. Referring to the
+sectional illustration at <a href="#Fig048">Fig. 48</a>, it will be seen that there
+is a hot-air passage with a choke-valve; the primary venturi
+appears at B; J is its gasoline jet, and V is a spring-loaded
+idling valve in a fixed air opening. These parts
+constitute the primary system. In the secondary system
+A is a cold-air passage, T a butterfly valve and J a gasoline
+jet discharging into the cold-air passage. This system
+is brought into operation by opening the butterfly T.
+A connection between the butterfly T and the throttle, not
+shown, throws the butterfly wide open when the throttle
+is not quite wide open; at all other times the butterfly<span class='pagenum'><a name="Page_132" id="Page_132">[132]</a></span>
+is held closed by a spring. The cylindrical chamber at
+the right of the mixing chamber has an extension E of
+reduced diameter connecting it with the intake manifold
+through a passage D. A restricted opening connects the
+float chamber with the cylindrical chamber so that the
+gasoline level is the same in both. A loosely fitting plunger
+P in the cylindrical chamber has an upward extension
+into the small part of the chamber. O is a small air
+opening and M is a passage from the cylindrical chamber
+to the mixing chamber. Air constantly passes through
+this when the carburetor is in operation. The carburetor
+is really two in one. The primary carburetor is made up
+of a central jet in a venturi passage. The float chamber
+is eccentric. In the air passage there is a fixed opening,
+and additional air is taken in by the opening through
+suction of a spring-opposed air valve. The second stage,
+which comes into play as soon as the carburetor is called
+upon for additional mixture above low medium speeds,
+is made up of an independent air passage containing another
+air valve. As the valve is opened this jet is uncovered,
+and air is led past it. For easy starting an
+extra passage leads from the float bowl passage to a point
+above the throttle. All the suction falls upon this passage
+when the throttle is closed. The passage contains a plunger
+and acts as a pick-up device. When the vacuum increases
+the plunger rises and shuts off the flow of gasoline
+from the intake passage. As the throttle is opened the
+vacuum in the intake passage is broken, and the plunger
+falls, causing gasoline to gather above it. This is immediately
+drawn through the pick-up passage and gives the
+desired mixture for acceleration.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig048" id="Fig048"></a>
+<img src="images/illo126.png" alt="Fig. 48" width="450" height="338" />
+<p class="caption">Fig. 48.&mdash;The Ball and Ball Two-Stage Carburetor.</p></div>
+
+<h3><a name="SecV_17" id="SecV_17"></a>MASTER MULTIPLE-JET CARBURETOR</h3>
+
+<p>This carburetor, shown in detail in <a href="#Fig049">Figs. 49</a> and <a href="#Fig050">50</a>,
+has been very popular in racing cars and aviation engines
+because of exceptionally good pick-up qualities and its
+thorough atomization of fuel. Its principle of operation
+is the breaking up of the fuel by a series of jets, which<span class='pagenum'><a name="Page_133" id="Page_133">[133]</a></span>
+vary in number from fourteen to twenty-one, according
+to the size of the carburetor. These are uncovered by
+opening the throttle, which is curved&mdash;a patented feature&mdash;to
+secure the correct progression of jets. The carburetor
+has an eccentric float chamber, from which the gasoline
+is led to the jet piece from which the jets stand up
+in a row. The tops of these jets are closed until the
+throttle is opened far enough to pass them, which it does
+progressively. The air opening is at the bottom, and the
+throttle opening is such that a modified venturi is formed.<span class='pagenum'><a name="Page_134" id="Page_134">[134]</a></span>
+The throttle is carried in a cylindrical barrel with the jets
+placed below it, and the passage from the barrel to the
+intake is arranged so that there is no interruption in the
+flow. For easy starting a dash-controlled shutter closes
+off the air, throwing the suction on the jets, thus giving
+a rich mixture.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig049" id="Fig049"></a>
+<img src="images/illo128.png" alt="Fig. 49" width="450" height="508" />
+<p class="caption">Fig. 49.&mdash;The Master Carburetor.</p></div>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig050" id="Fig050"></a>
+<img src="images/illo129.png" alt="Fig. 50" width="450" height="400" />
+<p class="caption">Fig. 50.&mdash;Sectional View of Master Carburetor Showing Parts.</p></div>
+
+<p>The only adjustment is for idling, and once that is
+fixed it need never be touched. This is in the form of
+a screw and regulates the position of the throttle when
+at idling position. The dash control has high-speed, normal
+and rich-starting positions. In installing the Master
+carburetor the float chamber may be turned either toward
+the radiator or driver&#8217;s seat. If the float is turned toward
+the radiator, however, a forward lug plate should be
+ordered; otherwise it will be difficult to install the control.
+The throttle lever must go all the way to the stop lug<span class='pagenum'><a name="Page_135" id="Page_135">[135]</a></span>
+or maximum power will not be secured. In adjusting the
+idle screw it is turned in for rich and out for lean.</p>
+
+<h3><a name="SecV_18" id="SecV_18"></a>COMPOUND NOZZLE ZENITH CARBURETOR</h3>
+
+<p>The Zenith carburetor, shown at <a href="#Fig051">Fig. 51</a>, has become
+very popular for airplane engine use because of its simplicity,
+as mixture compensation is secured by a compensating
+compound nozzle principle that works very well in
+practice. To illustrate this principle briefly, let us consider
+the elementary type of carburetor or mixing valve,
+as shown in <a href="#Fig052">Fig. 52</a>, A. It consists of a single jet or
+spraying nozzle placed in the path of the incoming air
+and fed from the usual float chamber. It is a natural<span class='pagenum'><a name="Page_137"
+id="Page_137">[137]</a></span><span class='pagenum'><a name="Page_136" id="Page_136"></a></span>
+inference to suppose that as the speed of the motor increases,
+both the flow of air and of gasoline will increase
+in the same proportion. Unhappily, such is not the case.
+There is a law of liquid bodies which states that the flow
+of gasoline from the jet increases under suction faster
+than the flow of air, giving a mixture which grows richer
+and richer&mdash;a mixture containing a much higher percentage
+of gasoline at high suction than at low. The tendency
+is shown by the accompanying curve (<a href="#Fig052">Fig. 52</a>, B), which
+gives the ratio of gasoline to air at varying speeds from
+this type of jet. The mixture is practically constant only
+between narrow limits and at very high speed. The most
+common method of correcting this defect is by putting
+various auxiliary air valves which, adding air, tends to
+dilute this mixture as it gets too rich. It is difficult with
+makeshift devices to gauge this dilution accurately for
+every motor speed.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig051" id="Fig051"></a>
+<img src="images/illo130.png" alt="Fig. 51" width="400" height="393" />
+<p class="caption">Fig. 51.&mdash;Sectional View of Zenith Compound Nozzle Compensating
+Carburetor.</p></div>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig052" id="Fig052"></a>
+<img src="images/illo131.png" alt="Fig. 52" width="600" height="404" />
+<p class="caption">Fig. 52.&mdash;Diagrams Explaining Action of Baverey Compound Nozzle Used in Zenith Carburetor.</p></div>
+
+<p>Now, if we have a jet which grows richer as the suction
+increases, the opposite type of jet is one which would
+grow leaner under similar conditions. Baverey, the inventor
+of the Zenith, discovered the principle of the constant
+flow device which is shown in <a href="#Fig052">Fig. 52</a>, C. Here
+a certain fixed amount of gasoline determined by the opening
+I is permitted to flow by gravity into the well J open
+to the air. The suction at jet H has no effect upon the
+gravity compensator I because the suction is destroyed
+by the open well J. The compensator, then, delivers a
+steady rate of flow per unit of time, and as the motor
+suction increases more air is drawn up, while the amount
+of gasoline remains the same and the mixture grows
+poorer and poorer. <a href="#Fig052">Fig. 52</a>, D, shows this curve.</p>
+
+<p>By combining these two types of rich and poor mixture
+carburetors the Zenith compound nozzle was evolved. In
+<a href="#Fig052">Fig. 52</a>, E, we have both the direct suction or richer type
+leading through pipe E and nozzle G and the &#8220;constant
+flow&#8221; device of Baverey shown at J, I, K and nozzle H.
+One counteracts the defects of the other, so that from
+the cranking of the motor to its highest speed there is<span class='pagenum'><a name="Page_138" id="Page_138">[138]</a></span>
+a constant ratio of air and gasoline to supply efficient
+combustion.</p>
+
+<p>In addition to the compound nozzle the Zenith is
+equipped with a starting and idling well, shown in the
+<a href="#Fig051">cut</a> of Model L carburetor at P and J. This terminates
+in a priming hole at the edge of the butterfly valve,
+where the suction is greatest when this valve is slightly
+open. The gasoline is drawn up by the suction at the
+priming hole and, mixed with the air rushing by the butterfly,
+gives an ideal slow speed mixture. At higher speeds
+with the butterfly valve opened further the priming well
+ceases to operate and the compound nozzle drains the well
+and compensates correctly for any motor speed.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig053" id="Fig053"></a>
+<img src="images/illo133.png" alt="Fig. 53" width="500" height="329" />
+<p class="caption">Fig. 53.&mdash;The Zenith Duplex Carburetor for Airplane Motors of the V Type.</p></div>
+
+<p>With the coming of the double motor containing eight
+or twelve cylinders arranged in two V blocks, the question
+of good carburetion has been a problem requiring much
+study. The single carburetor has given only indifferent
+results due to the strong cross suction in the inlet manifold
+from one set of cylinders to the other. This naturally
+led to the adoption of two carburetors in which each
+set of cylinders was independently fed by a separate carburetor.<span class='pagenum'><a name="Page_139" id="Page_139">[139]</a></span>
+Results from this system were very good when
+the two carburetors were working exactly in unison, but
+as it was extremely difficult to accomplish this co-operation,
+especially where the adjustable type was employed,
+this system never gained in favor. The next logical step
+was the Zenith Duplex, shown at <a href="#Fig053">Fig. 53</a>. This consists
+of two separate and distinct carburetors joined together
+so that a common gasoline float chamber and air inlet
+could be used by both. It does away with cross suction
+in the manifold because each set of cylinders has a separate<span class='pagenum'><a name="Page_140" id="Page_140">[140]</a></span>
+intake of its own. It does away with two carburetors
+and makes for simplicity. The practical application
+of the Zenith carburetor to the Curtiss 90 horse-power
+OX-2 motor used on the JN-4 standard training machine
+is shown at <a href="#Fig054">Fig. 54</a>, which outlines a rear view of the
+engine in question. The carburetor is carried low to permit
+of fuel supply from a gravity tank carried back of
+the motor.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig054" id="Fig054"></a>
+<img src="images/illo134.jpg" alt="Fig. 54" width="450" height="495" />
+<p class="caption">Fig. 54.&mdash;Rear View of Curtiss OX-2 90 Horse-Power Airplane Motor
+Showing Carburetor Location and Hot Air Leads.</p></div>
+
+<h3><a name="SecV_19" id="SecV_19"></a>UTILITY OF GASOLINE STRAINERS</h3>
+
+<p>Many carburetors include a filtering screen at the point
+where the liquid enters the float chamber in order to keep
+dirt or any other foreign matter which may be present
+in the fuel from entering the float chamber. This is not
+general practice, however, and the majority of vaporizers
+do not include a filter in their construction. It is very
+desirable that the dirt should be kept out of the carburetor
+because it may get under the float control fuel valve
+and cause flooding by keeping it raised from its seat. If
+it finds its way into the spray nozzle it may block the
+opening so that no gasoline will issue or may so constrict
+the passage that only very small quantities of fuel will
+be supplied the mixture. Where the carburetor itself is
+not provided with a filtering screen a simple filter is
+usually installed in the pipe line between the gasoline
+tank and the float chamber.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig055" id="Fig055"></a>
+<img src="images/illo136.png" alt="Fig. 55" width="450" height="469" />
+<p class="caption">Fig. 55.&mdash;Types of Strainers Interposed Between Vaporizer and Gasoline
+Tank to Prevent Water or Dirt Passing Into Carbureting Device.</p></div>
+
+<p>Some simple forms of filters and separators are shown
+at <a href="#Fig055">Fig. 55</a>. That at A consists of a simple brass casting
+having a readily detachable gauze screen and a settling
+chamber of sufficient capacity to allow the foreign matter
+to settle to the bottom, from which it is drained out by
+a pet cock. Any water or dirt in the gasoline will settle
+to the bottom of the chamber, and as all fuel delivered
+to the carburetor must pass through the wire gauze screen
+it is not likely to contain impurities when it reaches the
+float chamber. The heavier particles, such as scale from
+the tank or dirt and even water, all of which have greater
+weight than the gasoline, will sink to the bottom of the<span class='pagenum'><a name="Page_141" id="Page_141">[141]</a></span>
+chamber, whereas light particles, such as lint, will be prevented
+from flowing into the carburetor by the filtering
+screen.</p>
+
+<p>The filtering device shown at B is a larger appliance
+than that shown at A, and should be more efficient as a
+separator because the gasoline is forced to pass through
+three filtering screens before it reaches the carburetor.
+The gasoline enters the device shown at C through a bent
+pipe which leads directly to the settling chamber and
+from thence through a wire gauze screen to the upper
+compartment which leads to the carburetor. The device
+shown at D is a combination strainer, drain, and sediment<span class='pagenum'><a name="Page_142" id="Page_142">[142]</a></span>
+cup. The filtering screen is held in place by a
+spring and both are removed by taking out a plug at the
+bottom of the device. The shut-off valve at the top of
+the device is interposed between the sediment cup and
+the carburetor. This separating device is incorporated
+with the gasoline tank and forms an integral part of the
+gasoline supply system. The other types shown are designed
+to be interposed between the gasoline tank and
+the carburetor at any point in the pipe line where they
+may be conveniently placed.</p>
+
+<h3><a name="SecV_20" id="SecV_20"></a>INTAKE MANIFOLD DESIGN AND CONSTRUCTION</h3>
+
+<p>On four- and six-cylinder engines and in fact on all
+multiple-cylinder forms, it is important that the piping
+leading from the carburetor to the cylinders be made in
+such a way that the various cylinders will receive their
+full quota of gas and that each cylinder will receive its
+charge at about the same point in the cycle of operations.
+In order to make the passages direct the bends should
+be as few as possible, and when curves are necessary they
+should be of large radius because an abrupt corner will not
+only impede gas flow but will tend to promote condensation
+of the fuel. Every precaution should be taken with four- and
+six-cylinder engines to insure equitable gas distribution
+to the valve chambers if regular action of the
+power plant is desired. If the gas pipe has many turns
+and angles it will be difficult to charge all cylinders properly.
+On some six-cylinder aviation engines, two carburetors
+are used because of trouble experienced with manifolds
+designed for one carburetor. Duplex carburetors
+are necessary to secure the best results from eight- and
+twelve-cylinder V engines.</p>
+
+<p>The problem of intake piping is simplified to some
+extent on block motors where the intake passage is cored
+in the cylinder casting and where but one short pipe is
+needed to join this passage to the carburetor. If the
+cylinders are cast in pairs a simple pipe of T or Y form
+can be used with success. When the engine is of a type<span class='pagenum'><a name="Page_143" id="Page_143">[143]</a></span>
+using individual cylinder castings, especially in the six-cylinder
+power plants, the proper application and installation
+of suitable piping is a difficult problem. The reader
+is referred to the various engine designs outlined to ascertain
+how the inlet piping has been arranged on representative
+aviation engines. Intake piping is constructed
+in two ways, the most common method being to cast the
+manifold of brass or aluminum. The other method, which
+is more costly, is to use a built-up construction of copper
+or brass tubing with cast metal elbows and Y pieces. One
+of the disadvantages advanced against the cast manifold
+is that blowholes may exist which produce imperfect castings
+and which will cause mixture troubles because the
+entering gas from the carburetor, which may be of proper
+proportions, is diluted by the excess air which leaks in
+through the porous casting. Another factor of some moment
+is that the roughness of the walls has a certain
+amount of friction which tends to reduce the velocity of
+the gases, and when projecting pieces are present, such
+as core wire or other points of metal, these tend to collect
+the drops of liquid fuel and thus promote condensation.
+The advantage of the built-up construction is that the
+walls of the tubing are very smooth, and as the castings
+are small it is not difficult to clean them out thoroughly
+before they are incorporated in the manifold. The tubing
+and castings are joined together by hard soldering, brazing
+or autogenous welding.</p>
+
+<h3><a name="SecV_21" id="SecV_21"></a>COMPENSATING FOR VARYING ATMOSPHERIC CONDITIONS</h3>
+
+<p>The low-grade gasoline used at the present time makes
+it necessary to use vaporizers that are more susceptible
+to atmospheric variations than when higher grade and
+more volatile liquids are vaporized. Sudden temperature
+changes, sometimes being as much as forty degrees rise
+or fall in twelve hours, affect the mixture proportions to
+some extent, and not only changes in temperature but
+variations in altitude also have a bearing on mixture proportions
+by affecting both gasoline and air. As the temperature<span class='pagenum'><a name="Page_144" id="Page_144">[144]</a></span>
+falls the specific gravity of the gasoline increases
+and it becomes heavier, this producing difficulty in vaporizing.
+The tendency of very cold air is to condense gasoline
+instead of vaporizing it and therefore it is necessary
+to supply heated air to some carburetors to obtain proper
+mixtures during cold weather. In order that the gas mixtures
+will ignite properly the fuel must be vaporized and
+thoroughly mixed with the entering air either by heat or
+high velocity of the gases. The application of air stoves
+to the Curtiss OX-2 motor is clearly shown at <a href="#Fig054">Fig. 54</a>. It
+will be seen that flexible metal pipes are used to convey
+the heated air to the air intakes of the duplex mixing
+chamber.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig056" id="Fig056"></a>
+<img src="images/illo139.png" alt="Fig. 56" width="450" height="343" />
+<p class="caption">Fig. 56.&mdash;Chart Showing Diminution of Air Pressure as Altitude Increases.</p></div>
+
+<h3><a name="SecV_22" id="SecV_22"></a>HOW HIGH ALTITUDE AFFECTS POWER</h3>
+
+<p>Any internal combustion engine will show less power
+at high altitudes than it will deliver at sea level, and this
+has caused a great deal of questioning. &#8220;There is a good<span class='pagenum'><a name="Page_145" id="Page_145">[145]</a></span>
+reason for this,&#8221; says a writer in &#8220;Motor Age,&#8221; &#8220;and
+it is a physical impossibility for the engine to do otherwise.
+The difference is due to the lower atmospheric
+pressure the higher up we get. That is, at sea level the
+atmosphere has a pressure of 14.7 pounds per square inch;
+at 5,000 feet above sea level the pressure is approximately
+12.13 pounds per square inch, and at 10,000 feet it is 10
+pounds per square inch. From this it will be seen that
+the final pressure attained after the piston has driven
+the gas into compressed condition ready for firing is lower
+as the atmospheric pressure drops. This means that there
+is not so much power in the compressed charge of gas the
+higher up you get above sea level.</p>
+
+<p>&#8220;For example, suppose the compression ratio to be
+4<sup>1</sup>&#8260;<sub>2</sub> to 1; in other words, suppose the air space above the
+piston to have 4<sup>1</sup>&#8260;<sub>2</sub> times the volume when the piston is
+at the bottom of its stroke that it has when the piston is
+at the top of the stroke. That is a common compression
+ratio for an average motor, and is chosen because it is
+considered to be the best for maximum horse-power and
+in order that the compression pressure will not be so high
+as to cause pre-ignition. Knowing the compression ratio,
+we can determine the final pressure immediately before
+ignition by substituting in the standard formula:</p>
+
+<table class="formula" summary="Formula p 145">
+
+<tr>
+<td rowspan="2" class="center">P<sup>1</sup>&nbsp;=&nbsp;</td>
+<td rowspan="2" class="center fsize150">(</td>
+<td class="center bb">V</td>
+<td rowspan="2" class="center fsize150">)</td>
+<td class="center"><sup>1.3</sup></td>
+</tr>
+
+<tr>
+<td class="center">&nbsp;V<sup>1</sup>&nbsp;</td>
+</tr>
+
+</table>
+
+<p>in which P is the atmospheric pressure; P<sup>1</sup> is the final
+pressure, and V/V<sup>1</sup> is the compression ratio, therefore P<sup>1</sup> =
+14.7&nbsp;(4.5)<sup>1.3</sup> = 104 pounds per square inch, absolute.</p>
+
+<p>&#8220;That is, 104 pounds per square inch is the most efficient
+final compression pressure to have for this engine
+at sea level, since it comes directly from the compression
+ratio.</p>
+
+<p>&#8220;Now supposing we consider that the altitude is 7,000<span class='pagenum'><a name="Page_146" id="Page_146">[146]</a></span>
+feet above sea level. At this height the atmospheric pressure
+is 11.25 pounds per square inch, approximately. In
+this case we can again substitute in the formula, using
+the new atmospheric pressure figure. The equation becomes:</p>
+
+<p>
+P<sup>1</sup> = 11.25&nbsp;(4.5)<sup>1.3</sup>&mdash;79.4 pounds per square inch, absolute.
+</p>
+
+<p>&#8220;Therefore we now have a final compression pressure
+of only 79.4 pounds per square inch, which is considerably
+below the pressure we have just found to be the most
+efficient for the motor. The resulting power drop is evident.</p>
+
+<p>&#8220;It should be borne in mind that these final compression
+pressures are absolute pressures&mdash;that is, they include
+the atmospheric pressure. In the first case, to get
+the pressure above atmospheric you would subtract 14.7
+and in the latter 11.25 would have to be deducted. In
+other words, where the sea level compression is 89.3 pounds
+per square inch above the atmosphere, the same motor
+will have only a compression pressure of 68.15 pounds
+per square inch above the atmosphere at 7,000 feet elevation.</p>
+
+<p>&#8220;From the above it is evident that in order to bring
+the final compression pressure up to the efficient figure
+we have determined, a different compression ratio would
+have to be used. That is, the final volume would have
+to be less, and as it is impossible to vary this to meet
+the conditions of altitude, the loss of power cannot be
+helped except by the replacing of the standard pistons
+with some that are longer above the wrist-pin so as to
+reduce the space above the pistons when on top center.
+Then if the ratio is thereby raised to some such figures
+as 5 to 1, the engine will again have its proper final pressure,
+but it will still not have as much power as it would
+have at sea level, since the horse-power varies directly
+with the atmospheric pressure, final compression being
+kept constant. That is, at 7,000 feet the horse-power of<span class='pagenum'><a name="Page_147" id="Page_147">[147]</a></span>
+an engine that had 40 horse-power at sea level would be
+equal to</p>
+
+<table class="formula" summary="Formula p 147">
+
+<tr>
+<td class="center bb">11.25</td>
+<td rowspan="2" class="left">&nbsp;= 30.6 horse-power.</td>
+</tr>
+
+<tr>
+<td class="center">14.7</td>
+</tr>
+
+</table>
+
+<p>&#8220;If the original compression ratio of 4.5 were retained,
+the drop in horse-power would be even greater than this.
+These computations and remarks will make it clear that
+the designer who contemplates building an airplane for
+high altitude use should see to it that it is of sufficient
+power to compensate for the drop that is inevitable when
+it is up in the air. This is often illustrated in stationary
+gas-engine installations. An engine that had a sea-level
+rating amply sufficient for the work required, might not
+be powerful enough when brought up several thousand
+feet.&#8221; When one considers that airplanes attain heights
+of over 18,000 feet, it will be evident that an ample margin
+of engine power is necessary.</p>
+
+<h3><a name="SecV_23" id="SecV_23"></a>THE DIESEL SYSTEM</h3>
+
+<p>A system of fuel supply developed by the late Dr.
+Diesel, a German chemist and engineer, is attracting considerable
+attention at the present time on account of the
+ability of the Diesel engine to burn low-grade fuels, such
+as crude petroleum. In this system the engines are built
+so that very high compressions are used, and only pure
+air is taken into the cylinder on the induction stroke.
+This is compressed to a pressure of about 500 pounds
+per square inch, and sufficient heat is produced by this
+compression to explode a hydrocarbon mixture. As the
+air which is compressed to this high point cannot burn,
+the fuel is introduced into the cylinder combustion chamber
+under still higher compression than that of the compressed
+air, and as it is injected in a fine stream it is
+immediately vaporized because of the heat. Just as soon
+as the compressed air becomes thoroughly saturated with
+the liquid fuel, it will explode on account of the degree of<span class='pagenum'><a name="Page_148" id="Page_148">[148]</a></span>
+heat present in the combustion chamber. Such motors
+have been used in marine and stationary applications, but
+are not practical for airplanes or motor cars because of
+lack of flexibility and great weight in proportion to power
+developed. The Diesel engine is the standard power plant
+used in submarine boats and motor ships, as its efficiency
+renders it particularly well adapted for large units.</p>
+
+<h3><a name="SecV_24" id="SecV_24"></a>NOTES ON CARBURETOR INSTALLATION IN AIRPLANES</h3>
+
+<p>A writer in &#8220;The Aeroplane,&#8221; an English publication,
+discourses on some features of carburetor installation that
+may be of interest to the aviation student, so portions of
+the dissertation are reproduced herewith.</p>
+
+<div class="blockquot"><p>&#8220;Users of airplanes fitted with ordinary type carburetors will
+do well to note carefully the way in which these are fitted, for
+several costly machines have been burnt lately through the sheer
+carelessness of their users. These particular machines were fitted
+with a high powered V-type engine, made by a firm which is
+famous as manufacturers of automobiles <i>de luxe</i>. In these engines
+there are four carburetors, mounted in the V between the cylinders.
+When the engine is fitted as a tractor, the float chambers are in
+front of the jet chambers. Consequently, when the tail of the
+machine is resting on the ground, the jets are lower than the level
+of the gasoline in the float chamber.</p>
+
+<p>&#8220;Quite naturally, the gasoline runs out of the jet, if it is left
+turned on when the machine is standing in its normal position,
+and trickles into the V at the top of the crank-case. Thence it
+runs down to the tail of the engine, where the magnetos are fitted,
+and saturates them. If left long enough, the gasoline manages
+to soak well into the fuselage before evaporating. And what does
+evaporate makes an inflammable gas in the forward cockpit. Then
+some one comes along and starts up the engine. The spark-gap
+of the magneto gives one flash, and the whole front of the machine
+proceeds to give a Fourth of July performance forthwith. Naturally,
+one safeguard is to turn the petrol off directly the machine
+lands. Another is never to turn it on till the engine is actually
+being started up.</p>
+
+<p>&#8220;One would be asking too much of the human boy&mdash;who is
+officially regarded as the only person fit to fly an aeroplane&mdash;if
+one depended upon his memory of such a detail to save his machine,
+though one might perhaps reasonably expect the older pilots
+to remember not to forget. Even so, other means of prevention<span class='pagenum'><a name="Page_149" id="Page_149">[149]</a></span>
+are preferable, for fire is quite as likely to occur from just the
+same cause if the engine happens to be a trifle obstinate in starting,
+and so gives the carburetors several minutes in which to drip&mdash;in
+which operation they would probably be assisted by air-mechanics
+&#8216;tickling&#8217; them.</p>
+
+<p>&#8220;One way out of the trouble is to fit drip tins under the jet
+chamber to catch the gasoline as it falls. This is all very well
+just to prevent fire while the machine is being started up, but it
+will not save it if it is left standing with the tail on the ground
+and the petrol turned on, for the drip tins will then fill up and
+run over. And if it catches then, the contents of the drip tins
+merely add fuel to the fire.</p>
+
+<h4><i>Reversing Carburetors</i></h4>
+
+<p>&#8220;Yet another way is to turn the carburetors round, so that
+the float chambers are behind the jets, and so come below them
+when the tail is on the ground, thus cutting off the gasoline low
+down in the jets. There seems to be no particular mechanical
+difficulty about this, though I must confess that I did not note
+very carefully whether the reversal of the float chambers would
+make them foul any other fittings on the engine. It has been
+argued, however, that doing this would starve the engine of gasoline
+when climbing at a steep angle, as the gasoline would then
+be lowered in the jets and need more suction to get into the
+cylinders. This is rather a pretty point of amateur motor mechanics
+to discuss, for, obviously, when the same engine is used
+as a &#8216;pusher&#8217; instead of a tractor, the jets are in front of the
+floats, and there seems to be no falling off in power.</p>
+
+<h4><i>Starvation of Mixture</i></h4>
+
+<p>&#8220;Moreover, the higher a machine goes the lower is the atmospheric
+pressure, and, consequently, the less is the amount of air
+sucked in at each induction stroke. This means, of course, that
+with the gasoline supply the mixture at high altitudes is too
+rich, so that, in order to get precisely the right mixture when very
+high up, it is necessary to reduce the gasoline supply by screwing
+down the needle valve between the tank and the carburetor&mdash;at
+least, that has been the experience of various high-flying pilots.
+No doubt something might be done in the way of forced air feed
+to compensate for reduced atmospheric pressure, but it remains
+to be proved whether the extra weight of mechanism involved
+would pay for the extra power obtained. Variable compression
+might do something, also, to even things up, but here, also, weight
+of mechanism has to be considered.</p>
+
+<p>&#8220;In any case, at present, the higher one goes the more the<span class='pagenum'><a name="Page_150" id="Page_150">[150]</a></span>
+power of the engine is reduced, for less air means a less volume
+of mixture per cylinder, and as the petrol feed has to be starved
+to suit the smaller amount of air available, this means further loss
+of power. I do not know whether anyone has evolved a carburetor
+which automatically starves the gasoline feed when high up,
+but it seems possible that when an airplane is sagging about &#8216;up
+against the ceiling&#8217;&mdash;as a French pilot described the absolute
+limit of climb for his particular machine&mdash;it might be a good
+thing to have the jets in front of the float chamber, for then a
+certain amount of automatic starvation would take place.</p>
+
+<p>&#8220;When a machine is right up at its limiting height, and the
+pilot is doing his best to make it go higher still, it is probably
+flying with its tail as low as the pilot dares to let it go, and the
+lateral and longitudinal controls are on the verge of vanishing,
+so that if the carburetor jets are behind the float chambers there
+is bound to be an over-rich mixture in any case. There is even
+a possibility of a careless or ignorant pilot carrying on in this tail-down
+position till one set of cylinders cuts out altogether, in which
+case the carburetor feeding that set may flood over, just as if the
+machine were on the ground, and the whole thing may catch fire.
+Whereas, with the jets in front of the floats, though the mixture
+may starve a trifle, there is, at any rate, no danger of fire through
+climbing with the tail down.</p>
+
+<h4><i>A Diving Danger</i></h4>
+
+<p>&#8220;On the other hand, in a &#8216;pusher&#8217; with this type of engine,
+if the jets are in their normal position&mdash;which is in front of the
+floats&mdash;there is danger of fire in a dive. That is to say, if the
+pilot throttles right down, or switches off and relies on air pressure
+on his propeller to start the engine again, so that the gasoline
+is flooding over out of the jets instead of being sucked into the
+engine, there may be flooding over the magnetos if the dive is very
+steep and prolonged. In any case, a long dive will mean a certain
+amount of flooding, and, probably, a good deal of choking and
+spitting by the engine before it gets rid of the over-rich mixture
+and picks up steady firing again. Which may indicate to young
+pilots that it is not good to come down too low under such circumstances,
+trusting entirely to their engines to pick up at once
+and get going before they hit the ground.</p>
+
+<p>&#8220;On the whole, it seems that it might be better practice to set
+the carburetors thwartwise of engines, for then jets and floats
+would always be at approximately the same level, no matter what
+the longitudinal position of the machine, and it is never long
+enough in one position at a big lateral angle to raise any serious
+carburetor troubles. Car manufacturers who dive cheerfully into<span class='pagenum'><a name="Page_151" id="Page_151">[151]</a></span>
+the troubled waters of aero-engine designs are a trifle apt to forget
+that their engines are put into positions on airplanes which
+would be positively indecent in a motor car. An angle of 1 in 10
+is the exception on a car, but it is common on an airplane, and
+no one ever heard of a car going down a hill of 10 to 1&mdash;which is
+not quite a vertical dive. Therefore, there is every excuse for a
+well-designed and properly brought-up carburetor misbehaving
+itself in an aeroplane.</p>
+
+<p>&#8220;It seems, then, that it is up to the manufacturers to produce
+better carburetors&mdash;say, with the jet central with the float. But
+it also behooves the user to show ordinary common sense in handling
+the material at present available, and not to make a practice
+of burning up $25,000 worth or so of airplane just because
+he is too lazy to turn off his gasoline, or to have the tail of his
+machine lifted up while he is tinkering with his engines.&#8221;</p></div>
+
+<h3><a name="SecV_25" id="SecV_25"></a>NOTES ON CARBURETOR ADJUSTMENT</h3>
+
+<p>The modern float feed carburetor is a delicate and
+nicely balanced appliance that requires a certain amount
+of attention and care in order to obtain the best results.
+The adjustments can only be made by one possessing an
+intelligent knowledge of carburetor construction and must
+never be made unless the reason for changing the old adjustment
+is understood. Before altering the adjustment
+of the leading forms of carburetors, a few hints regarding
+the quality to be obtained in the mixture should be given
+some consideration, as if these are properly understood
+this knowledge will prove of great assistance in adjusting
+the vaporizer to give a good working proportion of fuel
+and air. There is some question regarding the best mixture
+proportions and it is estimated that gas will be
+explosive in which the proportions of fuel vapor and air
+will vary from one part of the former to a wide range
+included between four and eighteen parts of the latter.
+A one to four mixture is much too rich, while the one
+in eighteen is much too lean to provide positive ignition.</p>
+
+<p>A rich mixture should be avoided because the excessive
+fuel used will deposit carbon and will soot the cylinder
+walls, combustion chamber interior, piston top and valves
+and also tend to overheat the motor. A rich mixture will<span class='pagenum'><a name="Page_152" id="Page_152">[152]</a></span>
+also seriously interfere with flexible control of the engine,
+as it will choke up on low throttle and run well on open
+throttle when the full amount of gas is needed. A rich
+mixture may be quickly discovered by black smoke issuing
+from the muffler, the exhaust gas having a very pungent
+odor. If the mixture contains a surplus of air there will
+be popping sounds in the carburetor, which is commonly
+termed &#8220;blowing back.&#8221; To adjust a carburetor is not
+a difficult matter when the purpose of the various control
+members is understood. The first thing to do in adjusting
+a carburetor is to start the motor and to retard the sparking
+lever so the motor will run slowly leaving the throttle
+about half open. In order to ascertain if the mixture is
+too rich cut down the gasoline flow gradually by screwing
+down the needle valve until the motor commences to run
+irregularly or misfire. Close the needle valves as far as
+possible without having the engine come to a stop, and
+after having found the minimum amount of fuel gradually
+unscrew the adjusting valve until you arrive at the point
+where the engine develops its highest speed. When this
+adjustment is secured the lock nut is screwed in place so
+the needle valve will keep the adjustment. The next point
+to look out for is regulation of the auxiliary air supply on
+those types of carburetors where an adjustable air valve
+is provided. This is done by advancing the spark lever
+and opening the throttle. The air valve is first opened
+or the spring tension reduced to a point where the engine
+misfires or pops back in the carburetor. When the point
+of maximum air supply the engine will run on is thus determined,
+the air valve spring may be tightened by screwing
+in on the regulating screw until the point is reached
+where an appreciable speeding up of the engine is noticed.
+If both fuel and air valves are set right, it will be possible
+to accelerate the engine speed uniformly without interfering
+with regularity of engine operation by moving the
+throttle lever or accelerator pedal from its closed to its
+wide open position, this being done with the spark lever
+advanced. All types of carburetors do not have the same<span class='pagenum'><a name="Page_153" id="Page_153">[153]</a></span>
+means of adjustment; in fact, some adjust only with the
+gasoline regulating needle; others must have a complete
+change of spray nozzles; while in others the mixture proportions
+may be varied only by adjustment of the quantity
+of entering air. Changing the float level is effective in
+some carburetors, but this should never be done unless it
+is certain that the level is not correct. Full instructions
+for locating carburetion troubles will be given in proper
+sequence.</p>
+
+<p>It is a fact well known to experienced repairmen and
+motorists that atmospheric conditions have much to do
+with carburetor action. It is often observed that a motor
+seems to develop more power at night than during the
+day, a circumstance which is attributed to the presence of
+more moisture in the cooler night air. Likewise, taking
+a motor from sea level to an altitude of 10,000 feet involves
+using rarefied air in the engine cylinders and atmospheric
+pressures ranging from 14.7 pounds at sea
+level to 10.1 pounds per square inch at the high altitude.
+All carburetors will require some adjustment in the course
+of any material change from one level to another. Great
+changes of altitude also have a marked effect on the cooling
+system of an airplane. Water boils at 212 degrees F.
+only at sea level. At an altitude of 10,000 feet it will
+boil at a temperature nineteen degrees lower, or 193 degrees
+F.</p>
+
+<p>In high altitudes the reduced atmospheric pressure,
+for 5,000 feet or higher than sea level, results in not
+enough air reaching the mixture, so that either the auxiliary
+air opening has to be increased, or the gasoline in
+the mixture cut down. If the user is to be continually
+at high altitudes he should immediately purchase either
+a larger dome or a smaller strangling tube, mentioning
+the size carburetor that is at present in use and the type
+of motor that it is on, including details as to the bore
+and stroke. The smaller strangling tube makes an increased
+suction at the spray nozzle; the air will have to
+be readjusted to meet it and you can use more auxiliary<span class='pagenum'><a name="Page_154" id="Page_154">[154]</a></span>
+air, which is necessary. The effect on the motor without
+a smaller strangling tube is a perceptible sluggishness and
+failure to speed up to its normal crank-shaft revolutions,
+as well as failure to give power. It means that about one-third
+of the regular speed is cut out. The reduced atmospheric
+pressure reduces the power of the explosion,
+in that there is not the same quantity of oxygen in the
+combustion chamber as at sea level; to increase the amount
+taken in, you must also increase the gasoline speed, which
+is done by an increased suction through the smaller strangling
+aperture. Some forms of carburetors are affected
+more than others by changes of altitude, which explains
+why the Zenith is so widely employed for airplane engine
+use. The compensating nozzle construction is not influenced
+as much by changes of altitude as the simpler nozzle
+types are.</p>
+
+<hr class="c25" />
+<p class='pagenum'><a name="Page_155" id="Page_155">[155]</a></p>
+<h2><a name="ChVI" id="ChVI"></a>CHAPTER VI</h2>
+
+<div class="chapsec"><p><a href="#SecVI_1">Early Ignition Systems</a>&mdash;<a href="#SecVI_2">Electrical Ignition Best</a>&mdash;<a
+href="#SecVI_3">Fundamentals of Magnetism Outlined</a>&mdash;<a href="#SecVI_4">Forms of Magneto</a>&mdash;<a href="#SecVI_5">Zones of
+Magnetic Influence</a>&mdash;<a href="#SecVI_6">How Magnets are Made</a>&mdash;<a href="#SecVI_7">Electricity and Magnetism
+Related</a>&mdash;<a href="#SecVI_8">Basic Principles of Magneto Action</a>&mdash;<a href="#SecVI_9">Essential Parts of Magneto and
+Functions</a>&mdash;<a href="#SecVI_10">Transformer Coil Systems</a>&mdash;<a href="#SecVI_11">True High Tension Type</a>&mdash;<a
+href="#SecVI_12">The Berling Magneto</a>&mdash;<a href="#SecVI_13a">Timing</a> and <a href="#SecVI_13b">Care</a>&mdash;<a
+href="#SecVI_14">The Dixie Magneto</a>&mdash;<a href="#SecVI_15">Spark Plug Design and Application</a>&mdash;<a href="#SecVI_16">Two-Spark
+Ignition</a>&mdash;<a href="#SecVI_17">Special Airplane Plug</a>.</p></div>
+
+<h3><a name="SecVI_1" id="SecVI_1"></a>EARLY IGNITION SYSTEMS</h3>
+
+<p>One of the most important auxiliary groups of the
+gasoline engine comprising the airplane power plant and
+one absolutely necessary to insure engine action is the
+ignition system or the method employed of kindling the
+compressed gas in the cylinder to produce an explosion
+and useful power. The ignition system has been fully
+as well developed as other parts of the engine, and at
+the present time practically all ignition systems follow
+principles which have become standard through wide acceptance.</p>
+
+<p>During the early stages of development of the gasoline
+engine various methods of exploding the charge of combustible
+gas in the cylinder were employed. On some of
+the earliest engines a flame burned close to the cylinder
+head, and at the proper time for ignition a slide or valve
+moved to provide an opening which permitted the flame
+to ignite the gas back of the piston. This system was
+practical only on the primitive form of gas engines in
+which the charge was not compressed before ignition.
+Later, when it was found desirable to compress the gas
+a certain degree before exploding it, an incandescent platinum
+tube in the combustion chamber, which was kept
+in a heated condition by a flame burning in it, exploded
+the gas. The naked flame was not suitable in this application<span class='pagenum'><a name="Page_156" id="Page_156">[156]</a></span>
+because when the slide was opened to provide communication
+between the flame and the gas the compressed
+charge escaped from the cylinder with enough pressure to
+blow out the flame at times and thus cause irregular ignition.
+When the flame was housed in a platinum tube
+it was protected from the direct action of the gas, and
+as long as the tube was maintained at the proper point
+of incandescence regular ignition was obtained.</p>
+
+<p>Some engineers utilized the property of gases firing
+themselves if compressed to a sufficient degree, while
+others depended upon the heat stored in the cylinder-head
+to fire the highly compressed gas. None of these methods
+were practical in their application to motor car engines
+because they did not permit flexible engine action which
+is so desirable. At the present time, electrical ignition
+systems in which the compressed gas is exploded by the
+heating value of the minute electric arc or spark in the
+cylinder are standard, and the general practice seems to
+be toward the use of mechanical producers of electricity
+rather than chemical batteries.</p>
+
+<h3><a name="SecVI_2" id="SecVI_2"></a>ELECTRICAL IGNITION BEST</h3>
+
+<p>Two general forms of electrical ignition systems may
+be used, the most popular being that in which a current
+of electricity under high tension is made to leap a gap
+or air space between the points of the sparking plug
+screwed into the cylinder. The other form, which has
+been almost entirely abandoned in automobile and which
+was never used with airplane engine practice, but which
+is still used to some extent on marine engines, is called
+the low-tension system because current of low voltage is
+used and the spark is produced by moving electrodes in
+the combustion chamber.</p>
+
+<p>The essential elements of any electrical ignition system,
+either high or low tension, are: First, a simple and
+practical method of current production; second, suitable
+timing apparatus to cause the spark to occur at the right
+point in the cycle of engine action; third, suitable wiring<span class='pagenum'><a name="Page_157" id="Page_157">[157]</a></span>
+and other apparatus to convey the current produced by
+the generator to the sparking member in the cylinder.</p>
+
+<p>The various appliances necessary to secure prompt ignition
+of the compressed gases should be described in some
+detail because of the importance of the ignition system.
+It is patent that the scope of a work of this character
+does not permit one to go fully into the theory and principles
+of operation of all appliances which may be used
+in connection with gasoline motor ignition, but at the same
+time it is important that the elementary principles be
+considered to some extent in order that the reader should
+have a proper understanding of the very essential ignition
+apparatus. The first point considered will be the common
+methods of generating the electricity, then the appliances
+to utilize it and produce the required spark in the cylinder.
+Inasmuch as magneto ignition is universally used
+in connection with airplane engine ignition it will not be
+necessary to consider battery ignition systems.</p>
+
+<h3><a name="SecVI_3" id="SecVI_3"></a>FUNDAMENTALS OF MAGNETISM OUTLINED</h3>
+
+<p>To properly understand the phenomena and forces involved
+in the generation of electrical energy by mechanical
+means it is necessary to become familiar with some of the
+elementary principles of magnetism and its relation to
+electricity. The following matter can be read with profit
+by those who are not familiar with the subject. Most
+persons know that magnetism exists in certain substances,
+but many are not able to grasp the terms used in describing
+the operation of various electrical devices because of
+not possessing a knowledge of the basic facts upon which
+the action of such apparatus is based.</p>
+
+<p>Magnetism is a property possessed by certain substances
+and is manifested by the ability to attract and
+repel other materials susceptible to its effects. When this
+phenomenon is manifested by a conductor or wire through
+which a current of electricity is flowing it is termed &#8220;electro-magnetism.&#8221;
+Magnetism and electricity are closely
+related, each being capable of producing the other. Practically<span class='pagenum'><a name="Page_158" id="Page_158">[158]</a></span>
+all of the phenomena manifested by materials which
+possess magnetic qualities naturally can be easily reproduced
+by passing a current of electricity through a body
+which, when not under electrical influence, is not a magnetic
+substance. Only certain substances show magnetic
+properties, these being iron, nickel, cobalt and their alloys.</p>
+
+<p>The earliest known substance possessing magnetic
+properties was a stone first found in Asia Minor. It
+was called the lodestone or leading stone, because of its
+tendency, if arranged so it could be moved freely, of pointing
+one particular portion toward the north. The compass
+of the ancient Chinese mariners was a piece of this material,
+now known to be iron ore, suspended by a light thread
+or floated on a cork in some liquid so one end would point
+toward the north magnetic pole of the earth. The reason
+that this stone was magnetic was hard to define for a
+time, until it was learned that the earth was one huge
+magnet and that the iron ore, being particularly susceptible,
+absorbed and retained some of this magnetism.</p>
+
+<p>Most of us are familiar with some of the properties of
+the magnet because of the extensive sale and use of small
+horseshoe magnets as toys. As they only cost a few pennies
+every one has owned one at some time or other and
+has experimented with various materials to see if they
+would be attracted. Small pieces of iron or steel were
+quickly attracted to the magnet and adhered to the pole
+pieces when brought within the zone of magnetic influence.
+It was soon learned that brass, copper, tin or zinc were
+not affected by the magnet. A simple experiment that
+serves to illustrate magnetic attraction of several substances
+is shown at A, <a href="#Fig057">Fig. 57</a>. In this, several balls are
+hung from a standard or support, one of these being of
+iron, another of steel. When a magnet is brought near
+either of these they will be attracted toward it, while the
+others will remain indifferent to the magnetic force.
+Experimenters soon learned that of the common metals
+only iron or steel were magnetic.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig057" id="Fig057"></a>
+<img src="images/illo154.png" alt="Fig. 57" width="400" height="521" />
+<p class="caption">Fig. 57.&mdash;Some Simple Experiments to Demonstrate Various Magnetic Phenomena
+and Clearly Outline Effects of Magnetism and Various Forms
+of Magnets.</p></div>
+
+<p>If the ordinary bar or horseshoe magnet be carefully<span class='pagenum'><a name="Page_159" id="Page_159">[159]</a></span>
+examined, one end will be found to be marked N. This
+indicates the north pole, while the other end is not usually
+marked and is the south pole. If the north pole of one
+magnet is brought near the south pole of another, a strong
+attraction will exist between them, this depending upon<span class='pagenum'><a name="Page_160" id="Page_160">[160]</a></span>
+the size of the magnets used and the air gap separating
+the poles. If the south pole of one magnet is brought
+close to the end of the same polarity of the other there
+will be a pronounced repulsion of like force. These facts
+are easily proved by the simple experiment outlined at
+B, <a href="#Fig057">Fig. 57</a>. A magnet will only attract or influence a
+substance having similar qualities. The like poles of
+magnets will repel each other because of the obvious impossibility
+of uniting two influences or forces of practically
+equal strength but flowing in opposite directions.
+The unlike poles of magnets attract each other because
+the force is flowing in the same direction. The flow of
+magnetism is through the magnet from south to north and
+the circuit is completed by the flow of magnetic influence
+through the air gap or metal armature bridging it from
+the north to the south pole.</p>
+
+<h3><a name="SecVI_4" id="SecVI_4"></a><a name="SecVI_5" id="SecVI_5"></a>FORMS OF MAGNETS AND ZONE OF MAGNETIC INFLUENCE
+DEFINED</h3>
+
+<p>Magnets are commonly made in two forms, either in
+the shape of a bar or horseshoe. These two forms are
+made in two types, simple or compound. The latter are
+composed of a number of magnets of the same form united
+so the ends of like polarity are laced together, and such
+a construction will be more efficient and have more strength
+than a simple magnet of the same weight. The two common
+forms of simple and compound magnets are shown
+at C, <a href="#Fig057">Fig. 57</a>. The zone in which a magnetic influence
+occurs is called the magnetic field, and this force can be
+graphically shown by means of imaginary lines, which
+are termed &#8220;lines of force.&#8221; As will be seen from the
+diagram at D, <a href="#Fig057">Fig. 57</a>, the lines show the direction of
+action of the magnetic force and also show its strength,
+as they are closer together and more numerous when the
+intensity of the magnetic field is at its maximum. A
+simple method of demonstrating the presence of the force
+is to lay a piece of thin paper over the pole pieces of either
+a bar or horseshoe magnet and sprinkle fine iron filings<span class='pagenum'><a name="Page_161" id="Page_161">[161]</a></span>
+on it. The particles of metal arrange themselves in very
+much the manner shown in the illustrations and prove
+that the magnetic field actually exists.</p>
+
+<p>The form of magnet used will materially affect the
+size and area of the magnetic field. It will be noted that
+the field will be concentrated to a greater extent with
+the horseshoe form because of the proximity of the poles.
+It should be understood that these lines have no actual
+existence, but are imaginary and assumed to exist only
+to show the way the magnetic field is distributed. The
+magnetic influence is always greater at the poles than
+at the center, and that is why a horseshoe or U-form
+magnet is used in practically all magnetos or dynamos.
+This greater attraction at the poles can be clearly demonstrated
+by sprinkling iron filings on bar and U magnets,
+as outlined at E, <a href="#Fig057">Fig. 57</a>. A large mass gathers at
+the pole pieces, gradually tapering down toward the point
+where the attraction is least.</p>
+
+<p>From the diagrams it will be seen that the flow of
+magnetism is from one pole to the other by means of
+curved paths between them. This circuit is completed
+by the magnetism flowing from one pole to the other
+through the magnet, and as this flow is continued as long
+as the body remains magnetic it constitutes a magnetic
+circuit. If this flow were temporarily interrupted by
+means of a conductor of electricity moving through the
+field there would be a current of electricity induced in
+the conductor every time it cut the lines of force. There
+are three kinds of magnetic circuits. A non-magnetic
+circuit is one in which the magnetic influence completes
+its circuit through some substance not susceptible to the
+force. A closed magnetic circuit is one in which the influence
+completes its circuit through some magnetic material
+which bridges the gap between the poles. A compound
+circuit is that in which the magnetic influence
+passes through magnetic substances and non-magnetic substances
+in order to complete its circuit.</p>
+
+<p class='pagenum'><a name="Page_162" id="Page_162">[162]</a></p>
+
+<h3><a name="SecVI_6" id="SecVI_6"></a>HOW IRON AND STEEL BARS ARE MADE MAGNETIC</h3>
+
+<p>Magnetism may be produced in two ways, by contact
+or induction. If a piece of steel is rubbed on a magnet
+it will be found a magnet when removed, having a north
+and south pole and all of the properties found in the
+energizing magnet. This is magnetizing by contact. A
+piece of steel will retain the magnetism imparted to it for
+a considerable length of time, and the influence that remains
+is known as residual magnetism. This property
+may be increased by alloying the steel with tungsten and
+hardening it before it is magnetized. Any material that
+will retain its magnetic influence after removal from the
+source of magnetism is known as a permanent magnet.
+If a piece of iron or steel is brought into the magnetic
+field of a powerful magnet it becomes a magnet without
+actual contact with the energizer. This is magnetizing
+by magnetic induction. If a powerful electric current
+flows through an insulated conductor wound around a
+piece of iron or steel it will make a magnet of it. This
+is magnetizing by electro-magnetic induction. A magnet
+made in this manner is termed an electro-magnet and
+usually the metal is of such a nature that it will not
+retain its magnetism when the current ceases to flow
+around it. Steel is used in all cases where permanent
+magnets are required, while soft iron is employed in all
+cases where an intermittent magnetic action is desired.
+Magneto field magnets are always made of tungsten steel
+alloy, so treated that it will retain its magnetism for
+lengthy periods.</p>
+
+<h3><a name="SecVI_7" id="SecVI_7"></a>ELECTRICITY AND MAGNETISM CLOSELY RELATED</h3>
+
+<p>There are many points in which magnetism and electricity
+are alike. For instance, air is a medium that offers
+considerable resistance to the passage of both magnetic
+influence and electric energy, although it offers more
+resistance to the passage of the latter. Minerals like
+iron or steel are very easily influenced by magnetism and<span class='pagenum'><a name="Page_163" id="Page_163">[163]</a></span>
+easily penetrated by it. When one of these is present
+in the magnetic circuit the magnetism will flow through
+the metal. Any metal is a good conductor for the passage
+of the electric current, but few metals are good
+conductors of magnetic energy. A body of the proper
+metal will become a magnet due to induction if placed
+in the magnetic field, having a south pole where the lines
+of force enter it and a north pole where they pass out.</p>
+
+<p>We have seen that a magnet is constantly surrounded
+by a magnetic field and that an electrical conductor when
+carrying a current is also surrounded by a field of magnetic
+influence. Now if the conductor carrying a current
+of electricity will induce magnetism in a bar of iron or
+steel, by a reversal of this process, a magnetized iron or
+steel bar will produce a current of electricity in a conductor.
+It is upon this principle that the modern dynamo
+or magneto is constructed. If an electro-motive force is
+induced in a conductor by moving it across a field of magnetic
+influence, or by passing a magnetic field near a
+conductor, electricity is said to be generated by magneto-electric
+induction. All mechanical generators of the electric
+current using permanent steel magnets to produce a
+field of magnetic influence are of this type.</p>
+
+<h3><a name="SecVI_8" id="SecVI_8"></a>BASIC PRINCIPLES OF MAGNETO OUTLINED</h3>
+
+<p>The accompanying diagram, <a href="#Fig058">Fig. 58</a>, will show these
+principles very clearly. As stated on an earlier page,
+if the lines of force in the magnetic field are cut by a
+suitable conductor an electrical impulse will be produced
+in that conductor. In this simple machine the lines of
+force exist between the poles of a horseshoe magnet. The
+conductor, which in this case is a loop of copper wire,
+is mounted upon a spindle in order that it may be rotated
+in the magnetic field to cut the lines of magnetic influence
+present between the pole pieces. Both of the ends
+of this loop are connected, one with the insulated drum
+shown upon the shaft, the other to the shaft. Two metal
+brushes are employed to collect the current and cause it<span class='pagenum'><a name="Page_164" id="Page_164">[164]</a></span>
+to flow through the external circuit. It can be seen that
+when the shaft is turned in the direction of the arrow
+the loop will cut through the lines of magnetic influence
+and a current will be generated therein.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig058" id="Fig058"></a>
+<img src="images/illo159.png" alt="Fig. 58" width="450" height="462" />
+<p class="caption">Fig. 58.&mdash;Elementary Form of Magneto Showing Principal Parts Simplified
+to Make Method of Current Generation Clear.</p></div>
+
+<p>The pressure of the current and the amount produced
+vary in accordance to the rapidity with which the lines
+of magnetic influence are cut. The armature of a practical
+magneto, therefore, differs materially from that shown
+in the diagram. A large number of loops of wire would
+be mounted upon this shaft in order that the lines of
+magnetic influence would be cut a greater number of times
+in a given period and a core of iron used as a backing<span class='pagenum'><a name="Page_165" id="Page_165">[165]</a></span>
+for the wire. This would give a more rapid alternating
+current and a higher electro-motive force than would be
+the case with a smaller number of loops of wire.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig059" id="Fig059"></a>
+<img src="images/illo160.png" alt="Fig. 59" width="400" height="554" />
+<p class="caption">Fig. 59.&mdash;Showing How Strength of Magnetic Influence and of the Currents
+Induced in the Windings of Armature Vary with the Rapidity of
+Changes of Flow.</p></div>
+
+<p>The illustrations at <a href="#Fig059">Fig. 59</a> show a
+conventional double<span class='pagenum'><a name="Page_166" id="Page_166">[166]</a></span>
+winding armature and field magnetic of a practical magneto
+in part section and will serve to more fully emphasize
+the points previously made. If the armature or
+spindle were removed from between the pole pieces there
+would exist a field of magnetic influence as shown at <a href="#Fig057">Fig.
+57</a>, but the introduction of this component provides a
+conductor (the iron core) for the magnetic energy, regardless
+of its position, though the facility with which
+the influence will be transmitted depends entirely upon
+the position of the core. As shown at A, the magnetic
+flow is through the main body in a straight line, while
+at B, which position the armature has attained after one-eighth
+revolution, or 45 degrees travel in the direction
+of the arrow, the magnetism must pass through in the
+manner indicated. At C, which position is attained every
+half revolution, the magnetic energy abandons the longer
+path through the body of the core for the shorter passage
+offered by the side pieces, and the field thrown out by the
+cross bar disappears. On further rotation of the armature,
+as at D, the body of the core again becomes energized
+as the magnetic influence resumes its flow through
+it. These changes in the strength of the magnetic field
+when distorted by the armature core, as well as the intensity
+of the energy existing in the field, affect the
+windings, and the electrical energy induced therein corresponds
+in strength to the rapidity with which these
+changes in magnetic flow occur. The most pronounced
+changes in the strength of the field will occur as the armature
+passes from position B to D, because the magnetic
+field existing around the core will be destroyed and again
+re-established.</p>
+
+<p>During the most of the armature rotation the changes
+in strength will be slight and the currents induced in the
+wire correspondingly small; but at the instant the core
+becomes remagnetized, as the armature leaves position C,
+the current produced will be at its maximum, and it is necessary
+to so time the rotation of the armature that at this
+instant one of the cylinders is in condition to be fired. It<span class='pagenum'><a name="Page_167" id="Page_167">[167]</a></span>
+is imperative that the armature be driven in such relation
+to the crank-shaft that each production of maximum current
+coincides with the ignition point, this condition existing
+twice during each revolution of the armature, or at
+every 180 degrees travel. Each position shown corresponds
+to 45 degrees travel of the armature, or one-eighth
+of a turn, and it takes just three-eighths revolution to
+change the position from A to that shown at D.</p>
+
+<h3><a name="SecVI_9" id="SecVI_9"></a>ESSENTIAL PARTS OF A MAGNETO AND THEIR FUNCTIONS</h3>
+
+<p>The magnets which produce the influence that in turn
+induces the electrical energy in the winding or loops of
+wire on the armature, and which may have any even
+number of opposed poles, are called field magnets. The
+loops of wire which are mounted upon a suitable drum
+and rotate in the field of magnetic influence in order to
+cut the lines of force is called an armature winding, while
+the core is the metal portion. The entire assembly is
+called the armature. The exposed ends of the magnets
+are called pole pieces and the arrangement used to collect
+the current is either a commutator or a collector. The
+stationary pieces which bear against the collector or commutator
+and act as terminals for the outside circuit are
+called brushes. These brushes are often of copper, or
+some of its alloys, because copper has a greater electrical
+conductivity than any other metal.</p>
+
+<p>These brushes are nearly always of carbon, which
+is sometimes electroplated with copper to increase its
+electrical conductivity, though cylinders of copper wire
+gauze impregnated with graphite are utilized at times.
+Carbon is used because it is not so liable to cut the metal
+of the commutator as might be the case if the contact was
+of the metal to metal type. The reason for this is that
+carbon has the peculiar property in that it materially assists
+in the lubrication of the commutator, and being of
+soft, unctuous composition, will wear and conform to any
+irregularities on the surface of the metal collector rings.</p>
+
+<p>The magneto in common use consists of a number of<span class='pagenum'><a name="Page_168" id="Page_168">[168]</a></span>
+horseshoe magnets which are compound in form and attached
+to suitable cast-iron pole pieces used to collect and
+concentrate the magnetic influence of the various magnets.
+Between these pole pieces an armature rotates. This is
+usually shaped like a shuttle, around which are wound
+coils of insulated wire. These are composed of a large
+number of turns and the current produced depends in
+great measure upon the size of the wire and the number
+of turns per coil. An armature winding of large wire will
+deliver a current of great amperage, but of small voltage.
+An armature wound with very fine wire will deliver a
+current of high voltage but of low amperage. In the
+ordinary form of magneto, such as used for ignition, the
+current is alternating in character and the break in the
+circuit should be timed to occur when the armature is at
+the point of its greatest potential or pressure. Where
+such a generator is designed for direct current production
+the ends of the winding are attached to the segments of
+a commutator, but where the instrument is designed to
+deliver an alternating current one end of the winding is
+fastened to an insulator ring on one end of the armature
+shaft and the other end is grounded on the frame of the
+machine.</p>
+
+<p>The quantity of the current depends upon the strength
+of the magnetic field and the number of lines of magnetic
+influence acting through the armature. The electro-motive
+force varies as to the length of the armature winding and
+the number of revolutions at which the armature is rotated.</p>
+
+<h3><a name="SecVI_10" id="SecVI_10"></a>THE TRANSFORMER SYSTEM USES LOW VOLTAGE MAGNETO</h3>
+
+<p>The magneto in the various systems which employ a
+transformer coil is very similar to a low-tension generator
+in general construction, and the current delivered at
+the terminals seldom exceeds 100 volts. As it requires
+many times that potential or pressure to leap the gap
+which exists between the points of the conventional spark
+plug, a separate coil is placed in circuit to intensify the
+current to one of greater capacity. The essential parts<span class='pagenum'><a name="Page_169" id="Page_169">[169]</a></span>
+of such a system and their relation to each other are
+shown in diagrammatic form at <a href="#Fig060">Fig. 60</a> and as a complete
+system at <a href="#Fig061">Fig. 61</a>. As is true of other systems the
+magnetic influence is produced by permanent steel magnets
+clamped to the cast-iron pole pieces between which
+the armature rotates. At the point of greatest potential
+in the armature winding the current is broken by the
+contact breaker, which is actuated by a cam, and a current
+of higher value is induced in the secondary winding
+of the transformer coil when the low voltage current is
+passed through the primary winding.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig060" id="Fig060"></a>
+<img src="images/illo164.png" alt="Fig. 60" width="500" height="443" />
+<p class="caption">Fig. 60.&mdash;Diagrams Explaining Action of Low Tension Transformer Coil and
+True High Tension Magneto Ignition Systems.</p></div>
+
+<div class="figcenter" style="width: 550px;"><a name="Fig060a" id="Fig060a"></a>
+<p class="leftlink"><a href="images/large165.png">Large<br />image<br />(95 kB).</a></p>
+<img src="images/illo165.png" alt="Fig. 60A" width="550" height="345" />
+<p class="caption">Fig. 60A.&mdash;Side Sectional View of Bosch High-Tension Magneto Shows Disposition of Parts. End Elevation Depicts
+Arrangement of Interruptor and Distributor Mechanism.</p></div>
+
+<p>It will be noted that the points of the contact breaker
+are together except for the brief instant when separated
+by the action of the point of the cam upon the lever. It
+is obvious that the armature winding is short-circuited<span class='pagenum'><a
+name="Page_171" id="Page_171">[171]</a></span><span class='pagenum'><a name="Page_170" id="Page_170"></a></span>
+upon itself except when the contact points are separated.
+While the armature winding is thus short-circuited there
+will be practically no generation of current. When the
+points are separated there is a sudden flow of current
+through the primary winding of the transformer coil, inducing
+a secondary current in the other winding, which
+can be varied in strength by certain considerations in the
+preliminary design of the apparatus. This current of
+higher potential or voltage is conducted directly to the
+plug if the device is fitted to a single-cylinder engine, or
+to the distributor arm if fitted to a multiple-cylinder motor.
+The distributor consists of an insulator in which is
+placed a number of segments, one for each cylinder to
+be fired, and so spaced that the number of degrees between
+them correspond to the ignition points of the motor.
+A two-cylinder motor would have two segments, a three-cylinder,
+three segments, and so on within the capacity
+of the instrument. In the illustration a four-cylinder distributor
+is fitted, and the distributing arm is in contact<span class='pagenum'><a name="Page_172" id="Page_172">[172]</a></span>
+with the segment corresponding to the cylinder about to
+be fired.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig061" id="Fig061"></a>
+<img src="images/illo166.png" alt="Fig. 61" width="500" height="379" />
+<p class="caption">Fig. 61.&mdash;Berling Two-Spark Dual Ignition System.</p></div>
+
+<h3><a name="SecVI_11" id="SecVI_11"></a>TRUE HIGH-TENSION MAGNETOS ARE SELF-CONTAINED</h3>
+
+<p>The true high-tension magneto differs from the preceding
+inasmuch as the current of high voltage is produced
+in the armature winding direct, without the use of
+the separate coil. Instead of but one coil, the armature
+carries two, one of comparatively coarse wire, the other
+of many turns of finer wire. The arrangement of these
+windings can be readily ascertained by reference to the
+diagram B, <a href="#Fig060">Fig. 60</a>, which shows the principle of operation
+very clearly. The simplicity of the ignition system
+is evident by inspection of <a href="#Fig062">Fig. 62</a>. One end of the
+primary winding (coarse wire) is coupled or grounded
+to the armature core, and the other passes to the insulated
+part of the interrupter. While in some forms the
+interrupter or contact breaker mechanism does not revolve,
+the desired motion being imparted to the contact
+lever to separate the points of a revolving cam, in this
+the cam or tripping mechanism is stationary and the contact
+breaker revolves. This arrangement makes it possible
+to conduct the current from the revolving primary
+coil to the interrupter by a direct connection, eliminating<span class='pagenum'><a name="Page_173" id="Page_173">[173]</a></span>
+the use of brushes, which would otherwise be necessary.
+In other forms of this appliance where the winding is
+stationary, the interrupter may be operated by a revolving
+cam, though, if desired, the used of a brush at this
+point will permit this construction with a revolving
+winding.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig062" id="Fig062"></a>
+<img src="images/illo167.png" alt="Fig. 62" width="500" height="253" />
+<p class="caption">Fig. 62.&mdash;Berling Double-Spark Independent System.</p></div>
+
+<p>During the revolution of the armature the grounded
+lever makes and breaks contact with the insulated point,
+short-circuiting the primary winding upon itself until the
+armature reaches the proper position of maximum intensity
+of current production, at which time the circuit is
+broken, as in the former instance. One end of the secondary
+winding (fine wire) is grounded on the live end of
+the primary, the other end being attached to the revolving
+arm of the distributor mechanism. So long as a closed
+circuit is maintained feeble currents will pass through the
+primary winding, and so long as the contact points are
+together this condition will exist. When the current
+reaches its maximum value, because of the armature being
+in the best position, the cam operates the interrupter
+and the points are separated, breaking the short circuit
+which has existed in the primary winding.</p>
+
+<p>The secondary circuit has been open while the distributor
+arm has moved from one contact to another and there
+has been no flow of energy through this winding. While
+the electrical pressure will rise in this, even if the distributor
+arm contacted with one of the segments, there
+would be no spark at the plug until the contact points
+separated, because the current in the secondary winding
+would not be of sufficient strength. When the interrupter
+operates, however, the maximum primary current will be
+diverted from its short circuit and can flow to the ground
+only through the secondary winding and spark-plug circuit.
+The high pressure now existing in the secondary
+winding will be greatly increased by the sudden flow of
+primary current, and energy of high enough potential to
+successfully bridge the gap at the plug is thereby produced
+in the winding.</p>
+
+<p class='pagenum'><a name="Page_174" id="Page_174">[174]</a></p>
+
+<h3><a name="SecVI_12" id="SecVI_12"></a>THE BERLING MAGNETO</h3>
+
+<p>The Berling magneto is a true high tension type delivering
+two impulses per revolution, but it is made in a
+variety of forms, both single and double spark. Its principle
+of action does not differ in essentials from the high
+tension type previously described. This magneto is used
+on Curtiss aviation engines and will deliver sparks in a
+positive manner sufficient to insure ignition of engines up
+to 200 horse-power and at rotative speeds of the magneto
+armature up to 4,000 r. p. m. which is sufficient to take
+care of an eight-cylinder V engine running up to 2,000<span class='pagenum'><a name="Page_175" id="Page_175">[175]</a></span>
+r. p. m. The magneto is driven at crank-shaft speed on
+four-cylinder engines, at 1<sup>1</sup>&#8260;<sub>2</sub> times crank-shaft speed on six-cylinder
+engines and at twice crank-shaft speed on eight-cylinder
+V types. The types &#8220;D&#8221; and &#8220;DD&#8221; BERLING
+Magnetos are interchangeable with corresponding
+magnetos of other standard makes. The dimensions of
+the four-, six- and eight-cylinder types &#8220;D&#8221; and &#8220;DD&#8221;
+are all the same.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig063" id="Fig063"></a>
+<img src="images/illo169.jpg" alt="Fig. 63" width="450" height="447" />
+<p class="caption">Fig. 63.&mdash;Type DD Berling High Tension Magneto.</p></div>
+
+<p>The ideal method of driving the magneto is by means
+of flexible direct connecting coupling to a shaft intended
+for the purpose of driving the magneto. As the magneto
+must be driven at a high speed, a coupling of some
+flexibility is preferable. The employment of such a coupling
+will facilitate the mounting of the magneto, because
+a small inaccuracy in the lining up of the magneto with
+the driving shaft will be taken care of by the flexible
+coupling, whereas with a perfectly rigid coupling the
+line-up of the magneto must be absolutely accurate. Another
+advantage of the flexible coupling is that the vibration
+of the motor will not be as fully transmitted to the
+armature shaft on the magneto as in case a rigid coupling
+is used. This means prolonged life for the magneto.</p>
+
+<p>The next best method of driving the magneto is by
+means of a gear keyed to the armature shaft. When
+this method of driving is employed, great care must be
+exercised in providing sufficient clearance between the
+gear on the magneto and the driving gear. If there
+should be a tight spot between these two gears it will
+react disadvantageously on the magneto. The third
+available method is to drive the magneto by means of
+a chain. This is the least desirable of the three methods
+and should be resorted to only in case of absolute necessity.
+It is difficult to provide sufficient clearance when
+using a chain without rendering the timing less accurate
+and positive.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig064" id="Fig064"></a>
+<img src="images/illo171.png" alt="Fig. 64" width="450" height="481" />
+<p class="caption">Fig. 64.&mdash;Wiring Diagrams of Berling Magneto Ignition Systems.</p></div>
+
+<p><a href="#Fig064">Fig. 64</a>, A shows diagrammatically the circuit of the
+&#8220;D&#8221; type two-spark independent magneto and the switch
+used with it. In position OFF the primary winding<span class='pagenum'><a name="Page_176" id="Page_176">[176]</a></span>
+of the magneto is short-circuited and in this position
+the switch serves as an ordinary cut-out or grounding
+switch. In position &#8220;1&#8221; the switch connects the magneto
+in such a way that it operates as an ordinary
+single-spark magneto. In this position one end of the
+secondary winding is grounded to the body of the motor.
+This is the starting position. In this position of the
+switch the entire voltage generated in the magneto is
+concentrated at one spark-plug instead of being divided
+in half. With the motor turning over very slowly, as is
+the case in starting, the full voltage generated by the<span class='pagenum'><a name="Page_177" id="Page_177">[177]</a></span>
+magneto will not in all cases be sufficient to bridge simultaneously
+two spark gaps, but is amply sufficient to
+bridge one. Also, this position of the switch tends to
+retard the ignition and should be used in starting to
+prevent back-firing. With the switch in position &#8220;2&#8221;
+the magneto applies ignition to both plugs in each
+cylinder simultaneously. This is the normal running
+position.</p>
+
+<p><a href="#Fig064">Fig. 64</a>, B shows diagrammatically the circuit of the
+type &#8220;DD&#8221; BERLING high-tension two-spark dual magneto.
+This type is recommended for certain types of
+heavy-duty airplane motors, which it is impossible to turn
+over fast enough to give the magneto sufficient speed to
+generate even a single spark of volume great enough to
+ignite the gas in the cylinder. The dual feature consists
+of the addition to the magneto of a battery interrupter.
+The equipment consists of the magneto, coil and special
+high-tension switch. The coil is intended to operate on
+six volts. Either a storage battery or dry cells may be
+used.</p>
+
+<p>With the switch in the OFF position, the magneto is
+grounded, and the battery circuit is open. With the
+switch in the second or battery position marked &#8220;BAT,&#8221;
+one end of the secondary winding of the magneto is
+grounded, and the magneto operates as a single-spark
+magneto delivering high-tension current to the inside
+distributor, and the battery circuit being closed the high-tension
+current from the coil is delivered to the outside
+distributor. In this position the battery current is supplied
+to one set of spark plugs, no matter how slowly
+the motor is turned over, but as soon as the motor starts,
+the magneto supplies current as a single-spark magneto
+to the other set of the spark-plugs. After the engine is
+running, the switch should be thrown to the position
+marked &#8220;MAG.&#8221; The battery and coil are then disconnected,
+and the magneto furnishes ignition to both
+plugs in each cylinder. This is the normal running
+position. Either a non-vibrating coil type &#8220;N-1&#8221; is<span class='pagenum'><a name="Page_178" id="Page_178">[178]</a></span>
+furnished or a combined vibrating and non-vibrating coil
+type &#8220;VN-1.&#8221;</p>
+
+<h3><a name="SecVI_13a" id="SecVI_13a"></a>SETTING BERLING MAGNETO</h3>
+
+<p>The magneto may be set according to one of two
+different methods, the selection of which is, to some
+extent, governed by the characteristics of the engine,
+but largely due to the personal preference on the part
+of the user. In the first method described below, the
+most advantageous position of the piston for fully advanced
+ignition is determined in relation to the extreme
+advanced position of the magneto. In this case, the
+fully retarded ignition will not be a matter of selection,
+but the timing range of the magneto is wide enough to
+bring the fully retarded ignition after top-center position
+of the piston. The second method for the setting of the
+magneto fixes the fully retarded position of the magneto
+in relation to that position of the piston where fully
+retarded ignition is desired. In this case, the extreme
+advance position of the magneto will not always correspond
+with the best position of the piston for fully advanced
+ignition, and the amount of advance the magneto
+should have to meet ideal requirements in this respect
+must be determined by experiment.</p>
+
+<h4><i>First Method:</i></h4>
+
+<p>1. Designate one cylinder as cylinder No. 1.</p>
+
+<p>2. Turn the crank-shaft until the piston in cylinder
+No. 1 is in the position where the fully advanced spark
+is desired to occur.</p>
+
+<p>3. Remove the cover from the distributor block and
+turn the armature shaft in the direction of rotation of the
+magneto until the distributor finger-brush comes into
+such a position that this brush makes contact with the
+segment which is connected to the cable terminal marked
+&#8220;1.&#8221; This is either one of the two bottom segments,
+depending upon the direction of rotation.</p>
+
+<p>4. Place the cam housing in extreme advance, i.e.,<span class='pagenum'><a name="Page_179" id="Page_179">[179]</a></span>
+turn the cam housing until it stops, in the direction
+opposite to the direction of rotation of the armature.
+With the cam housing in this position, open the cover.</p>
+
+<p>5. With the armature in the approximate position as
+described in &#8220;3,&#8221; turn the armature slightly in either
+direction to such a point that the platinum points of the
+magneto interrupter will just begin to open at the end
+of the cam, adjacent to the fibre lever on the interrupter.</p>
+
+<p>6. With this exact position of the armature, fix the
+magneto to the driving member of the engine.</p>
+
+<h4><i>Second Method:</i></h4>
+
+<p>1. Designate one cylinder as cylinder No. 1.</p>
+
+<p>2. Turn the crank-shaft until the piston in cylinder
+No. 1 is in the position at which the fully retarded spark
+is desired to occur.</p>
+
+<p>3. Same as No. 3 under First Method.</p>
+
+<p>4. Place the cam housing in extreme retard, i.e., turn
+the cam housing until it stops, in the same direction as
+the direction of rotation of the armature. With the cam
+housing in this position, open the cover.</p>
+
+<p>5. Same as No. 5 under First Method.</p>
+
+<p>6. Same as No. 6 under First Method.</p>
+
+<h3>WIRING THE MAGNETO</h3>
+
+<p>The wiring of the magneto is clearly shown by <a href="#Fig064">wiring
+diagram</a>.</p>
+
+<p>First determine the sequence of firing for the cylinders
+and then connect the cables to the spark plug in the
+cylinders in proper sequence, beginning with cylinder
+No. 1 marked on the distributor block.</p>
+
+<p>The switch used with the independent type must be
+mounted in such a manner that there will be a metallic
+connection between the frame of the magneto and the
+metal portion of the switch.</p>
+
+<p>It is advisable to use a separate battery, either storage
+or dry cells, as a source of current for the dual equipment.<span class='pagenum'><a name="Page_180" id="Page_180">[180]</a></span>
+Connecting to the same battery that is used with
+the generator and other electrical equipment may cause
+trouble, as a &#8220;ground&#8221; in this battery causes the coil
+to overheat.</p>
+
+<h3><a name="SecVI_13b" id="SecVI_13b"></a>CARE AND MAINTENANCE</h3>
+
+<h4><i>Lubrication:</i></h4>
+
+<p>Use only the very best of oil for the oil cups.</p>
+
+<p>Put five drops of oil in the oil cup at the driving end
+of the magneto for every fifty hours of actual running.</p>
+
+<p>Put five drops of oil in the oil cup at the interrupter
+end of the magneto, located at one side of the cam
+housing, for every hundred hours of actual running.</p>
+
+<p>Lubricate the embossed cams in the cam housing with
+a thin film of vaseline every fifty hours of actual running.
+Wipe off all superfluous vaseline. Never use oil
+in the interrupter. Do not lubricate any other part of
+the interrupter.</p>
+
+<h4><i>Adjusting the Interrupter:</i></h4>
+
+<p>With the fibre lever in the center of one of the embossed
+cams, as at <a href="#Fig065">Fig. 65</a>, the opening between the
+platinum contacts should be not less than <span class="nowrap">.016&#8242;&#8242;</span> and not
+more than <span class="nowrap">.020&#8242;&#8242;.</span> The gauge riveted to the adjusting
+wrench should barely be able to pass between the contacts
+when fully open. The platinum contacts must be
+smoothed off with a very fine file. When in closed position,
+the platinum contacts should make contact with
+each other over their entire surfaces.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig065" id="Fig065"></a>
+<img src="images/illo176.png" alt="Fig. 65" width="400" height="257" />
+<p class="caption">Fig. 65.&mdash;The Berling Magneto Breaker Box Showing Contact Points
+Separated and Interruptor Lever on Cam.</p></div>
+
+<p>When inspecting the interrupter, make sure that the
+ground brush in the back of the interrupter base is
+making good contact with the surface on which it rubs.</p>
+
+<h4><i>Cleaning the Distributor:</i></h4>
+
+<p>The distributor block cover should be removed for
+inspection every twenty-five hours of actual running
+and the carbon deposit from the distributor finger-brush
+wiped off the distributor block by rubbing with a rag<span class='pagenum'><a name="Page_181" id="Page_181">[181]</a></span>
+or piece of waste dipped in gasoline or kerosene. The
+high-tension terminal brush on the side of the magneto
+should also be carefully inspected for proper tension.</p>
+
+<h3>LOCATING TROUBLE</h3>
+
+<p>Trouble in the ignition system is indicated by the
+motor &#8220;missing,&#8221; stopping entirely, or by inability to
+start.</p>
+
+<p>It is safe to assume that the trouble is not in the
+magneto, and the carburetor, gasoline supply and spark-plugs
+should first be investigated.</p>
+
+<p>If the magneto is suspected, the first thing to do is
+to determine if it will deliver a spark. To determine
+this, disconnect one of the high-tension leads from the
+spark-plug in one of the cylinders and place it so that
+there is approximately <span class="nowrap"><sup>1</sup>&#8260;<sub>16</sub>&#8242;&#8242;</span> between the terminal and
+the cylinder frame.</p>
+
+<p>Open the pet cocks on the other cylinders to prevent
+the engine from firing and turn over the engine until
+the piston is approaching the end of the compression<span class='pagenum'><a name="Page_182" id="Page_182">[182]</a></span>
+stroke in the cylinder from which the cable has been
+removed. Set the magneto in the advance position and
+rapidly rock the engine over the top-center position,
+observing closely if a spark occurs between the end of
+the high-tension cable and the frame.</p>
+
+<p>If the magneto is of the dual type, the trouble may
+be either in the magneto or in the battery or coil system,
+therefore disconnect the battery and place the switch
+in the position marked &#8220;MAG.&#8221; The magneto will then
+operate as an independent magneto and should spark
+in the proper manner. After this the battery system
+should be investigated. To test the operation of the
+battery and coil, examine all connections, making sure
+that they are clean and tight, and then with the switch,
+in the &#8220;BAT,&#8221; rock the piston slowly back and forth.
+If a type &#8220;VN-1&#8221; coil is used, a shower of sparks should
+jump between the high-tension cable terminal and the
+cylinder frame when the piston is in the correct position
+for firing. If no spark occurs, remove the cover from
+the coil and see that the vibrating tongue is free. If a
+type &#8220;N-1&#8221; coil is used, a single spark will occur. The
+battery should furnish six volts when connected to the
+coil, and this should also be verified.</p>
+
+<p>If the coil still refuses to give a spark and all connections
+are correct, the coil should be replaced and the
+defective coil returned to the manufacturer.</p>
+
+<p>If both magneto and coil give a spark when tested
+as just described, the spark-plugs should be investigated.
+To do this, disconnect the cables and remove
+the spark-plugs. Then reconnect the cables to the plugs
+and place them so that the frame portions of the plugs
+are in metallic connection with the frame of the motor.
+Then turn over the motor, thus revolving the magneto
+armature, and see if a spark is produced at the spark
+gaps of the plugs.</p>
+
+<p>The most common defects in spark-plugs are breaking
+down of the insulation, fouling due to carbon, or too large
+or small a spark gap. To clean the plugs a stiff brush<span class='pagenum'><a name="Page_183" id="Page_183">[183]</a></span>
+and gasoline should be used. The spark gap should be
+about <span class="nowrap"><sup>1</sup>&#8260;<sub>32</sub>&#8242;&#8242;</span>
+and never less than <span class="nowrap"><sup>1</sup>&#8260;<sub>64</sub>&#8242;&#8242;</span>. Too small a gap
+may have been caused by beads of metal forming due
+to the heat of the spark. Too long a gap may have been
+caused by the points burning off.</p>
+
+<p>If the magneto and spark plugs are in good condition
+and the engine does not run satisfactorily, the setting
+should be verified according to instructions previously
+given, and, if necessary, readjusted.</p>
+
+<p>Be careful to observe that both the type &#8220;VN-1&#8221; and
+type &#8220;N-1&#8221; coils are so arranged that the spark occurs
+on the opening of the contacts of the timer. As this is
+just the reverse of the usual operation, it should be carefully
+noted when any change in the setting of the timer
+is made. The timer on the dual type magneto is adjusted
+so that the battery spark occurs about <span class="nowrap">5&deg;</span>
+later<span class='pagenum'><a name="Page_184" id="Page_184">[184]</a></span>
+than the magneto spark. This provides an automatic
+advance as soon as the switch is thrown to the magneto
+position &#8220;MAG.&#8221; This relative timing can be easily
+adjusted by removing the interrupter and shifting the
+cam in the direction desired.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig066" id="Fig066"></a>
+<img src="images/illo178.jpg" alt="Fig. 66" width="450" height="367" />
+<p class="caption">Fig. 66.&mdash;The Dixie Model 60 for Six-Cylinder Airplane Engine Ignition.</p></div>
+
+<h3><a name="SecVI_14" id="SecVI_14"></a>THE DIXIE MAGNETO</h3>
+
+<p>The Dixie magneto, shown at <a href="#Fig066">Fig. 66</a>, operates on a
+different principle than the rotary armature type. It is
+used on the Hall-Scott and other aviation engines. In
+this magneto the rotating member consists of two pieces
+of magnetic material separated by a non-magnetic center
+piece. This member constitutes true rotating poles for
+the magnet and rotates in a field structure, composed of
+two laminated field pieces, riveted between two non-magnetic
+rings. The bearings for the rotating poles are<span class='pagenum'><a name="Page_185" id="Page_185">[185]</a></span>
+mounted in steel plates, which lie against the poles of the
+magnets. When the magnet poles rotate, the magnetic
+lines of force from each magnet pole are carried directly
+to the field pieces and through the windings, without
+reversal through the mass of the rotating member and
+with only a single air gap. There are no losses by flux
+reversal in the rotating part, such as take place in other<span class='pagenum'><a name="Page_186" id="Page_186">[186]</a></span>
+machines, and this is said to account for the high efficiency
+of the instrument.</p>
+
+<div class="figcenter" style="width: 550px;"><a name="Fig067" id="Fig067"></a>
+<img src="images/illo179.png" alt="Fig. 67" width="550" height="434" />
+<p class="caption">Fig. 67.&mdash;Installation Dimensions of Dixie Model 60 Magneto.</p></div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig068" id="Fig068"></a>
+<img src="images/illo180.png" alt="Fig. 68" width="400" height="492" />
+<p class="caption">Fig. 68.&mdash;The Rotating Elements of the Dixie Magneto.</p></div>
+
+<p>And this &#8220;Mason Principle&#8221; involved in the operation
+of the Dixie is simplified by a glance at the field structure,
+consisting of the non-magnetic rings, assembled to
+which are the field pieces between which the rotating
+poles revolve (see <a href="#Fig068">Fig. 68</a>). Rotating between the
+limbs of the magnets, these two pieces of magnetic material
+form true extensions to the poles of the magnets,
+and are, in consequence, <i>always</i> of the <i>same</i> polarity.
+It will be seen there is no reversal of the magnetism
+through them, and consequently no eddy current or hysteresis
+losses which are present in the usual rotor or
+inductor types. The simplicity features of construction
+stand out prominently here, in that there are no revolving
+windings, a detail entirely differing from the orthodox
+high-tension instrument. This simplicity becomes instantly
+apparent when it is found that the circuit breaker,
+instead of revolving as it does in other types, is stationary
+and that the whole breaker mechanism is exposed by
+simply turning the cover spring aside and removing
+cover. This makes inspection and adjustment particularly
+simple, and the fact that no special tool is necessary
+for adjustment of the platinum points&mdash;an ordinary
+small screw-driver is the whole &#8220;kit of tools&#8221; needed in
+the work of disassembling or assembling&mdash;is a feature of
+some value.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig069" id="Fig069"></a>
+<img src="images/illo182.png" alt="Fig. 69" width="500" height="511" />
+<p class="caption">Fig. 69.&mdash;Suggestions for Adjusting and Dismantling Dixie Magneto. A&mdash;Screw
+Driver Adjusts Contact Points. B&mdash;Distributor Block Removed.
+C&mdash;Taking off Magnets. D&mdash;Showing How Easily Condenser and High
+Tension Windings are Removed.</p></div>
+
+<p>With dust- and water-protecting casing removed, and
+one of the magnets withdrawn, as in <a href="#Fig069">Fig. 69</a>, the winding
+can be seen with its core resting on the field pole pieces
+and the primary lead attached to its side. An important
+feature of the high-tension winding is that the heads are
+of insulating material, and there is not the tendency for
+the high-tension current to jump to the side as in the
+ordinary armature type magneto. The high-tension current
+is carried to the distributor by means of an insulated
+block with a spindle, at one end of which is a spring
+brush bearing directly on the winding, thus shortening<span class='pagenum'><a name="Page_187" id="Page_187">[187]</a></span>
+the path of the high-tension current and eliminating the
+use of rubber spools and insulating parts. The moving
+parts of the magneto need never be disturbed if the high-tension
+winding is to be removed. This winding constitutes
+all of the magneto windings, no external spark
+coil being necessary. The condenser is placed directly
+above the winding and is easily removable by taking out
+two screws, instead of being placed in an armature where
+it is inaccessible except to an expert, and where it cannot
+be replaced except at the factory whence it emanated.</p>
+
+<p class='pagenum'><a name="Page_188" id="Page_188">[188]</a></p>
+
+<h3>CARE OF THE DIXIE MAGNETO</h3>
+
+<p>The bearings of the magneto are provided with oil
+cups and a few drops of light oil every 1,000 miles are
+sufficient. The breaker lever should be lubricated every
+1,000 miles with a drop of light oil, applied with a tooth-pick.
+The proper distance between the platinum points
+when separated should not exceed .020 or one-fiftieth of
+an inch. A gauge of the proper size is attached to the
+screwdriver furnished with the magneto. The platinum
+contacts should be kept clean and properly adjusted.
+Should the contacts become pitted, a fine file should be
+used to smooth them in order to permit them to come
+into perfect contact. The distributor block should be
+removed occasionally and inspected for an accumulation
+of carbon dust. The inside of the distributor block should
+be cleaned with a cloth moistened with gasoline and
+then wiped dry with a clean cloth. When replacing the
+block, care must be exercised in pushing the carbon brush
+into the socket. Do not pull out the carbon brushes in the
+distributor because you think there is not enough tension
+on the small brass springs. In order to obtain the most
+efficient results, the normal setting of the spark-plug
+points should not exceed .025 of an inch, and it is advisable
+to have the gap just right before a spark-plug is
+inserted.</p>
+
+<p>The spark-plug electrodes may be easily set by means
+of the gauge attached to the screwdriver. <i>The setting
+of the spark-plug points is an important function which
+is usually overlooked, with the result that the magneto
+is blamed when it is not at fault.</i></p>
+
+<h3>TIMING OF THE DIXIE MAGNETO</h3>
+
+<p>In order to obtain the utmost efficiency from the engine,
+the magneto must be correctly timed to it. This
+operation is usually performed when the magneto is fitted
+to the engine at the factory. The correct setting may
+vary according to individuality of the engine, and some<span class='pagenum'><a name="Page_190"
+id="Page_190">[190]</a></span><span class='pagenum'><a name="Page_189" id="Page_189"></a></span>
+engines may require an earlier setting in order to obtain
+the best results. However, should the occasion arise to
+retime the magneto, the procedure is as follows: Rotate
+the crank-shaft of the engine until one of the pistons,
+preferably that of cylinder No. 1, is <sup>1</sup>&#8260;<sub>16</sub> of an inch ahead
+of the end of the compression stroke. With the timing
+lever in full retard position, the driving shaft of the
+magneto should be rotated in the direction in which it
+will be driven. The circuit breaker should be closely
+observed and when the platinum contact points are about
+to separate, the drive gear or coupling should be secured
+to the drive shaft of the magneto. Care should be taken
+not to alter the position of the magneto shaft when
+tightening the nut to secure the gear or coupling, after
+which the magneto should be secured to its base. Remove
+the distributor block and determine which terminal
+of the block is in contact with the carbon brush of the
+distributor finger and connect with plug wire leading to
+No. 1 cylinder to this terminal. Connect the remaining
+plug wires in turn according to the proper sequence of
+firing of the cylinders. (See the wiring diagram for a
+typical six-cylinder engine at <a href="#Fig070">Fig. 70</a>.) A terminal on
+the end of the cover spring of the magneto is provided
+for the purpose of connecting the wire leading to a ground
+switch for stopping the engine.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig069a" id="Fig069a"></a>
+<p class="leftlink"><a href="images/large184.png">Large<br />image<br />(108 kB).</a></p>
+<img src="images/illo184.png" alt="Fig. 69A" width="600" height="394" />
+<p class="caption">Fig. 69A.&mdash;Sectional Views Outlining Construction of Dixie Magneto with Compound Distributor for Eight-Cylinder
+Engine Ignition.</p></div>
+
+<p>A special model or type of magneto is made for
+V engines which use a compound distributor construction
+instead of the simple type on the model illustrated
+and a different interior arrangement permits the production
+of four sparks per revolution of the rotors. This
+makes it possible to run the magneto slower than would
+be possible with the two-spark form. The application
+of two compound distributor magnetos of this type to a
+Thomas-Morse 135 horse-power motor of the eight-cylinder
+V pattern is clearly shown at <a href="#Fig071">Fig. 71</a>.</p>
+
+<p class='pagenum'><a name="Page_191" id="Page_191">[191]</a></p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig070" id="Fig070"></a>
+<p class="leftlink"><a href="images/large186.png">Large<br />image<br />(51 kB).</a></p>
+<img src="images/illo186.png" alt="Fig. 70" width="500" height="286" />
+<p class="caption">Fig. 70.&mdash;Wiring Diagram of Dixie Magneto Installation on Hall-Scott Six-Cylinder 125 Horse-Power
+Aeronautic Motor.</p></div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig071" id="Fig071"></a>
+<img src="images/illo187.jpg" alt="Fig. 71" width="400" height="495" />
+<p class="caption">Fig. 71.&mdash;How Magneto Ignition is Installed on Thomas-Morse 135 Horse-Power
+Motor.</p></div>
+
+<p class='pagenum'><a name="Page_192" id="Page_192">[192]</a></p>
+
+<h3><a name="SecVI_15" id="SecVI_15"></a>SPARK-PLUG DESIGN AND APPLICATION</h3>
+
+<p>With the high-tension system of ignition the spark is
+produced by a current of high voltage jumping between
+two points which break the complete circuit, which would
+exist otherwise in the secondary coil and its external
+connections. The spark-plug is a simple device which<span class='pagenum'><a name="Page_193" id="Page_193">[193]</a></span>
+consists of two terminal electrodes carried in a suitable
+shell member, which is screwed into the cylinder. Typical
+spark-plugs are shown in section at <a href="#Fig072">Fig. 72</a> and the
+construction can be easily understood. The secondary
+wire from the coil is attached to a terminal at the top
+of a central electrode member, which is supported in a
+bushing of some form of insulating material. The type
+shown at A employs a molded porcelain as an insulator,
+while that depicted at B uses a bushing of mica. The
+insulating bushing and electrode are housed in a steel
+body, which is provided with a screw thread at the bottom,
+by which means it is screwed into the combustion
+chamber.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig072" id="Fig072"></a>
+<img src="images/illo188.png" alt="Fig. 72" width="600" height="316" />
+<p class="caption">Fig. 72.&mdash;Spark-Plug Types Showing Construction and Arrangement
+of Parts.</p></div>
+
+<p>When porcelain is used as an insulating material it is
+kept from direct contact with the metal portion by some
+form of yielding packing, usually asbestos. This is necessary
+because the steel and porcelain have different
+coefficients of expansion and some flexibility must be
+provided at the joints to permit the materials to expand
+differently when heated. The steel body of the plug which
+is screwed into the cylinder is in metallic contact with it
+and carries sparking points which form one of the terminals
+of the air gap over which the spark occurs. The<span class='pagenum'><a name="Page_194" id="Page_194">[194]</a></span>
+current entering at the top of the plug cannot reach the
+ground, which is represented by the metal portion of the
+engine, until it has traversed the full length of the central
+electrode and overcome the resistance of the gap
+between it and the terminal point on the shell. The
+porcelain bushing is firmly seated against the asbestos
+packing by means of a brass screw gland which sets
+against a flange formed on the porcelain, and which
+screws into a thread at the upper portion of the plug
+body.</p>
+
+<p>The mica plug shown at B is somewhat simpler in
+construction than that shown at A. The mica core which
+keeps the central electrode separated from the steel body
+is composed of several layers of pure sheet mica wound
+around the steel rod longitudinally, and hundreds of
+stamped steel washers which are forced over this member
+and compacted under high pressure with some form of a
+binding material between them. Porcelain insulators are
+usually molded from high-grade clay and are approximately
+of the shapes desired by the designers of the plug.
+The central electrode may be held in place by mechanical
+means such as nuts, packings, and a shoulder on the rod,
+as shown at A. Another method sometimes used is to
+cement the electrode in place by means of some form of
+fire-clay cement. Whatever method of fastening is used,
+it is imperative that the joints be absolutely tight so that
+no gas can escape at the time of explosion. Porcelain
+is the material most widely used because it can be glazed
+so that it will not absorb oil, and it is subjected to such
+high temperature in baking that it is not liable to crack
+when heated.</p>
+
+<p>The spark-plugs may be screwed into any convenient
+part of the combustion chamber, the general practice
+being to install them in the caps over the inlet valves,
+or in the side of the combustion chamber, so the points
+will be directly in the path of the entering fresh gases
+from the carburetor.</p>
+
+<p>Other insulating materials sometimes used are glass,<span class='pagenum'><a name="Page_195" id="Page_195">[195]</a></span>
+steatite (which is a form of soapstone) and lava. Mica
+and porcelain are the two common materials used because
+they give the best results. Glass is liable to crack, while
+lava or the soapstone insulating bushings absorb oil.
+The spark gap of the average plug is equal to about
+<sup>1</sup>&#8260;<sub>32</sub> of an inch for coil ignition and <sup>1</sup>&#8260;<sub>40</sub> of an inch when
+used in magneto circuits. A simple gauge for determining
+the gap setting is the thickness of an ordinary visiting
+card for magneto plugs, or a space equal to the thickness
+of a worn dime for a coil plug. The insulating bushings
+are made in a number of different ways, and while details
+of construction vary, spark-plugs do not differ essentially
+in design. The dimensions of the standardized plug
+recommended by the S. A. E. are shown at <a href="#Fig073">Fig. 73</a>.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig073" id="Fig073"></a>
+<img src="images/illo190.png" alt="Fig. 73" width="500" height="356" />
+<p class="caption">Fig. 73.&mdash;Standard Airplane Engine Plug Suggested by S. A. E. Standards
+Committee.</p></div>
+
+<p>It is often desirable to have a water-tight joint between
+the high-tension cable and the terminal screw on
+top of the insulating bushing of the spark-plug, especially
+in marine applications. The plug shown at C, <a href="#Fig072">Fig. 72</a>,<span
+class='pagenum'><a name="Page_196" id="Page_196">[196]</a></span>
+is provided with an insulating member or hood of porcelain,
+which is secured by a clip in such a manner that it
+makes a water-tight connection. Should the porcelain
+of a conventional form of plug become covered with
+water or dirty oil, the high-tension current is apt to
+run down this conducting material on the porcelain and
+reach the ground without having to complete its circuit
+by jumping the air gap and producing a spark. It will
+be evident that wherever a plug is exposed to the elements,
+which is often the case in airplane service, that it
+should be protected by an insulating hood which will keep
+the insulator dry and prevent short circuiting of the
+spark. The same end can be attained by slipping an
+ordinary rubber nipple over the porcelain insulator of
+any conventional plug and bringing up one end over the
+cable.</p>
+
+<h3><a name="SecVI_16" id="SecVI_16"></a>TWO-SPARK IGNITION</h3>
+
+<p>On most aviation engines, especially those having large
+cylinders, it is sometimes difficult to secure complete
+combustion by using a single-spark plug. If the combustion
+is not rapid the efficiency of the engine will be
+reduced proportionately. The compressed charge in the
+cylinder does not ignite all at once or instantaneously,
+as many assume, but it is the strata of gas nearest the
+plug which is ignited first. This in turn sets fire to
+consecutive layers of the charge until the entire mass
+is aflame. One may compare the combustion of gas in
+the gas-engine cylinder to the phenomenon which obtains
+when a heavy object is thrown into a pool of still water.
+First a small circle is seen at the point where the object
+has passed into the water, this circle in turn inducing
+other and larger circles until the whole surface of the
+pool has been agitated from the one central point. The
+method of igniting the gas is very similar, as the spark
+ignites the circle of gas immediately adjacent to the
+sparking point, and this circle in turn ignites a little
+larger one concentric with it. The second circle of flame<span class='pagenum'><a name="Page_197" id="Page_197">[197]</a></span>
+sets fire to more of the gas, and finally the entire contents
+of the combustion chamber are burning.</p>
+
+<p>While ordinarily combustion is sufficiently rapid with
+a single plug so that the proper explosion is obtained at
+moderate engine speeds, if the engine is working fast and
+the cylinders are of large capacity more power may be
+obtained by setting fire to the mixture at two different
+points instead of but one. This may be accomplished by
+using two sparking-plugs in the cylinder instead of one,
+and experiments have shown that it is possible to gain
+from twenty-five to thirty per cent. in motor power at
+high speed with two-spark plugs, because the combustion
+of gas is accelerated by igniting the gas simultaneously
+in two places. The double-plug system on airplane engines
+is also a safeguard, as in event of failure of one
+plug in the cylinder the other would continue to fire the
+gas, and the engine will continue to function properly.</p>
+
+<p>In using magneto ignition some precautions are necessary
+relating to wiring and also the character of the spark-plugs
+employed. The conductor should be of good quality,
+have ample insulation, and be well protected from accumulations
+of oil, which would tend to decompose rubber
+insulation. It is customary to protect the wiring by running
+it through the conduits of fiber or metal tubing lined
+with insulating material. Multiple strand cables should
+be used for both primary and secondary wiring, and the
+insulation should be of rubber at least <sup>3</sup>&#8260;<sub>16</sub> inch thick.</p>
+
+<p>The spark-plugs commonly used for battery and coil
+ignition cannot always be employed when a magneto is
+fitted. The current produced by the mechanical generator
+has a greater amperage and more heat value than that
+obtained from transformer coils excited by battery current.
+The greater heat may burn or fuse the slender
+points used on some battery plugs and heavier electrodes
+are needed to resist the heating effect of the more intense
+arc. While the current has greater amperage it is not of
+as high potential or voltage as that commonly produced
+by the secondary winding of an induction coil, and it<span class='pagenum'><a name="Page_198" id="Page_198">[198]</a></span>
+cannot overcome as much of a gap. Manufacturers of
+magneto plugs usually set the spark points about <sup>1</sup>&#8260;<sub>64</sub> of
+an inch apart. The most efficient magneto plug has a
+plurality of points so that when the distance between one
+set becomes too great the spark will take place between
+one of the other pairs of electrodes which are not separated
+by so great an air space.</p>
+
+<h3><a name="SecVI_17" id="SecVI_17"></a>SPECIAL PLUGS FOR AIRPLANE WORK</h3>
+
+<p>Airplane work calls for special construction of spark-plugs,
+owing to the high compression used in the engines
+and the fact that they are operated on open throttle practically
+all the time, thus causing a great deal of heat to<span class='pagenum'><a name="Page_199" id="Page_199">[199]</a></span>
+be developed. The plug shown at <a href="#Fig074">Fig. 74</a> was recently
+described in &#8220;The Automobile,&#8221; and has been devised
+especially for airplane engines and automobile racing
+power plants. The core C is built up of mica washers,
+and has square shoulders. As mica washers of different
+sizes may be used, and accurate machining, such as is necessary
+with conical clamping surfaces, is not required,
+the plug can be produced economically. The square
+shoulders of the core afford two gasket seats, and when
+the core is clamped in the shell by means of check nut E,
+it is accurately centered and a tight joint is formed. This
+construction also makes a shorter plug than where conical
+fits are used, thus improving the heat radiation through
+the stem. The lower end of the shell is provided with a
+baffle plate O, which tends to keep the oil away from the
+mica. There are perforations L in this baffle plate to
+prevent burnt gases being pocketed behind the baffle plate
+and pre-igniting the new charge. This construction also
+brings the firing point out into the firing chamber of the
+engine, and has all the other advantages of a closed-end
+plug. The stem P is made of brass or copper, on account
+of their superior heat conductivity, and the electrode J
+is swedged into the bottom of the stem, as shown at K,
+in a secure manner.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig074" id="Fig074"></a>
+<img src="images/illo193.png" alt="Fig. 74" width="400" height="394" />
+<p class="caption">Fig. 74.&mdash;Special Mica Plug for Aviation Engines.</p></div>
+
+<p>The shell is finned, as shown at G, to provide greater
+heat radiating surface. There is also a fin F at the top
+of the stem, to increase the radiation of heat from the
+stem and electrode. The top of this finned portion is
+slightly countersunk, and the stem is riveted into same,
+thereby reducing the possibility of leakage past the
+threads on the stem. This finned portion is necked at A
+to take a slip terminal.</p>
+
+<p>In building up the core a small section of washers, I,
+is built up before the mica insulating tube D is placed on.
+This construction gives a better support to section I.
+Baffle plate O is bored out to allow the electrode J to
+pass through, and the clearance between baffle plate and
+electrode is made larger than the width of the gap between<span class='pagenum'><a name="Page_200" id="Page_200">[200]</a></span>
+the firing points, so that there is no danger of the
+spark jumping from the electrode to the baffle plate.</p>
+
+<p>This plug will be furnished either with or without the
+finned portion, to meet individual requirements. The
+manufacturers lay special stress upon the simplicity of
+construction and upon the method of clamping, which is
+claimed to make the plug absolutely gas-tight.</p>
+
+<hr class="c25" />
+<p class='pagenum'><a name="Page_201" id="Page_201">[201]</a></p>
+<h2><a name="ChVII" id="ChVII"></a>CHAPTER VII</h2>
+
+<div class="chapsec"><p><a href="#SecVII_1">Why Lubrication Is Necessary</a>&mdash;<a href="#SecVII_2">Friction Defined</a>&mdash;<a
+href="#SecVII_3">Theory of Lubrication</a>&mdash;<a href="#SecVII_4">Derivation of Lubricants</a>&mdash;<a href="#SecVII_5">Properties of
+Cylinder Oils</a>&mdash;<a href="#SecVII_6">Factors Influencing Lubrication System Selection</a>&mdash;<a href="#SecVII_7">Gnome Type
+Engines Use Castor Oil</a>&mdash;<a href="#SecVII_8">Hall-Scott Lubrication System</a>&mdash;<a href="#SecVII_9">Oil Supply by Constant
+Level Splash System</a>&mdash;<a href="#SecVII_10">Dry Crank-Case System Best for Airplane Engines</a>&mdash;<a href="#SecVII_11">Why
+Cooling Systems Are Necessary</a>&mdash;<a href="#SecVII_12">Cooling Systems Generally Applied</a>&mdash;<a href="#SecVII_13">Cooling by
+Positive Pump Circulation</a>&mdash;<a href="#SecVII_14">Thermo-Syphon System</a>&mdash;<a href="#SecVII_15">Direct Air-Cooling
+Methods</a>&mdash;<a href="#SecVII_16">Air-Cooled Engine Design Considerations</a>.</p></div>
+
+<h3><a name="SecVII_1" id="SecVII_1"></a>WHY LUBRICATION IS NECESSARY</h3>
+
+<p>The importance of minimizing friction at the various
+bearing surfaces of machines to secure mechanical efficiency
+is fully recognized by all mechanics, and proper
+lubricity of all parts of the mechanism is a very essential
+factor upon which the durability and successful operation
+of the motor car power plant depends. All of the moving
+members of the engine which are in contact with other
+portions, whether the motion is continuous or intermittent,
+of high or low velocity, or of rectilinear or continued
+rotary nature, should be provided with an adequate supply
+of oil. No other assemblage of mechanism is operated
+under conditions which are so much to its disadvantage
+as the motor car, and the tendency is toward a simplification
+of oiling methods so that the supply will be ample
+and automatically applied to the points needing it.</p>
+
+<p>In all machinery in motion the members which are in
+contact have a tendency to stick to each other, and the
+very minute projections which exist on even the smoothest
+of surfaces would have a tendency to cling or adhere
+to each other if the surfaces were not kept apart by some
+elastic and unctuous substance. This will flow or spread
+out over the surfaces and smooth out the inequalities existing<span class='pagenum'><a name="Page_202" id="Page_202">[202]</a></span>
+which tend to produce heat and retard motion of the
+pieces relative to each other.</p>
+
+<p>A general impression which obtains is that well machined
+surfaces are smooth, but while they are apparently
+free from roughness, and no projections are visible to the
+naked eye, any smooth bearing surface, even if very carefully
+ground, will have a rough appearance if examined
+with a magnifying glass. An exaggerated condition to
+illustrate this point is shown at <a href="#Fig075">Fig. 75</a>. The amount of
+friction will vary in proportion to the pressure on the
+surfaces in contact and will augment as the loads increase;
+the rougher surfaces will have more friction than
+smoother ones and soft bodies will produce more friction
+than hard substances.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig075" id="Fig075"></a>
+<img src="images/illo198.png" alt="Fig. 75" width="450" height="355" />
+<p class="caption">Fig. 75.&mdash;Showing Use of Magnifying Glass to Demonstrate that Apparently
+Smooth Metal Surfaces May Have Minute Irregularities which Produce
+Friction.</p></div>
+
+<h3><a name="SecVII_2" id="SecVII_2"></a>FRICTION DEFINED</h3>
+
+<p>Friction is always present in any mechanism as a resisting
+force that tends to retard motion and bring all
+moving parts to a state of rest. The absorption of power
+by friction may be gauged by the amount of heat which
+exists at the bearing points. Friction of solids may be
+divided into two classes: sliding friction, such as exists
+between the piston and cylinder, or the bearings of a
+gas-engine, and rolling friction, which is that present
+when the load is supported by ball or roller bearings, or
+that which exists between the tires or the driving wheels
+and the road. Engineers endeavor to keep friction losses
+as low as possible, and much care is taken in all modern
+airplane engines to provide adequate methods of lubrication,
+or anti-friction bearings at all points where considerable
+friction exists.</p>
+
+<h3><a name="SecVII_3" id="SecVII_3"></a>THEORY OF LUBRICATION</h3>
+
+<p>The reason a lubricant is supplied to bearing points
+will be easily understood if one considers that these
+elastic substances flow between the close fitting surfaces,
+and by filling up the minute depressions in the surfaces
+and covering the high spots act as a cushion which<span class='pagenum'><a name="Page_203" id="Page_203">[203]</a></span>
+absorbs the heat generated and takes the wear instead
+of the metallic bearing surface. The closer the parts fit
+together the more fluid the lubricant must be to pass
+between their surfaces, and at the same time it must
+possess sufficient body so that it will not be entirely
+forced out by the pressure existing between the parts.</p>
+
+<p>Oils should have good adhesive, as well as cohesive,
+qualities. The former are necessary so that the oil film
+will cling well to the surfaces of the bearings; the latter,
+so the oil particles will cling together and resist the tendency
+to separation which exists all the time the bearings
+are in operation. When used for gas-engine lubrication
+the oil should be capable of withstanding considerable
+heat in order that it will not be vaporized by the hot portions
+of the cylinder. It should have sufficient cold test
+so that it will remain fluid and flow readily at low temperature.
+Lubricants should be free from acid, or alkalies,<span class='pagenum'><a name="Page_204" id="Page_204">[204]</a></span>
+which tend to produce a chemical action with metals
+and result in corrosion of the parts to which they are
+applied. It is imperative that the oil be exactly the
+proper quality and nature for the purpose intended and
+that it be applied in a positive manner. The requirements
+may be briefly summarized as follows:</p>
+
+<p>First&mdash;It must have sufficient body to prevent seizing
+of the parts to which it is applied and between which it
+is depended upon to maintain an elastic film, and yet it
+must not have too much viscosity, in order to minimize
+the internal or fluid friction which exists between the
+particles of the lubricant itself.</p>
+
+<p>Second&mdash;The lubricant must not coagulate or gum;
+must not injure the parts to which it is applied, either by
+chemical action or by producing injurious deposits, and
+it should not evaporate readily.</p>
+
+<p>Third&mdash;The character of the work will demand that
+the oil should not vaporize when heated or thicken to such
+a point that it will not flow readily when cold.</p>
+
+<p>Fourth&mdash;The oil must be free from acid, alkalies, animal
+or vegetable fillers, or other injurious agencies.</p>
+
+<p>Fifth&mdash;It must be carefully selected for the work required
+and should be a good conductor of heat.</p>
+
+<h3><a name="SecVII_4" id="SecVII_4"></a>DERIVATION OF LUBRICANTS</h3>
+
+<p>The first oils which were used for lubricating machinery
+were obtained from animal and vegetable sources,
+though at the present time most unguents are of mineral
+derivation. Lubricants may exist as fluids, semifluids, or
+solids. The viscosity will vary from light spindle or
+dynamo oils, which have but little more body than kerosene,
+to the heaviest greases and tallows. The most common
+solid employed as a lubricant is graphite, sometimes
+termed &#8220;plumbago&#8221; or &#8220;black lead.&#8221; This substance is
+of mineral derivation.</p>
+
+<p>The disadvantage of oils of organic origin, such as
+those obtained from animal fats or vegetable substances,
+is that they will absorb oxygen from the atmosphere,<span class='pagenum'><a name="Page_205" id="Page_205">[205]</a></span>
+which causes them to thicken or become rancid. Such
+oils have a very poor cold test, as they solidify at comparatively
+high temperatures, and their flashing point is
+so low that they cannot be used at points where much
+heat exists. In most animal oils various acids are present
+in greater or less quantities, and for this reason they are
+not well adapted for lubricating metallic surfaces which
+may be raised high enough in temperature to cause decomposition
+of the oils.</p>
+
+<p>Lubricants derived from the crude petroleum are
+called &#8220;Oleonaphthas&#8221; and they are a product of the
+process of refining petroleum through which gasoline and
+kerosene are obtained. They are of lower cost than vegetable
+or animal oil, and as they are of non-organic origin,
+they do not become rancid or gummy by constant exposure
+to the air, and they will have no corrosive action
+on metals because they contain no deleterious substances
+in chemical composition. By the process of fractional
+distillation mineral oils of all grades can be obtained.
+They have a lower cold and higher flash test and there
+is not the liability of spontaneous combustion that exists
+with animal oils.</p>
+
+<p>The organic oils are derived from fatty substances,
+which are present in the bodies of all animals and in
+some portions of plants. The general method of extracting
+oil from animal bodies is by a rendering process,
+which consists of applying sufficient heat to liquefy the
+oil and then separating it from the tissue with which it
+is combined by compression. The only oil which is used
+to any extent in gas-engine lubrication that is not of
+mineral derivation is castor oil. This substance has been
+used on high-speed racing automobile engines and on
+airplane power plants. It is obtained from the seeds of
+the castor plant, which contain a large percentage of oil.</p>
+
+<p>Among the solid substances which may be used for
+lubricating purposes may be mentioned tallow, which is
+obtained from the fat of animals, and graphite and soapstone,
+which are of mineral derivation. Tallow is never<span class='pagenum'><a name="Page_206" id="Page_206">[206]</a></span>
+used at points where it will be exposed to much heat,
+though it is often employed as a filler for greases used
+in transmission gearing of autos. Graphite is sometimes
+mixed with oil and applied to cylinder lubrication, though
+it is most often used in connection with greases in the
+landing gear parts and for coating wires and cables of
+the airplane. Graphite is not affected by heat, cold, acids,
+or alkalies, and has a strong attraction for metal surfaces.
+It mixes readily with oils and greases and increases their
+efficiency in many applications. It is sometimes used
+where it would not be possible to use other lubricants
+because of extremes of temperature.</p>
+
+<p>The oils used for cylinder lubrication are obtained
+almost exclusively from crude petroleum derived from
+American wells. Special care must be taken in the selection
+of crude material, as every variety will not yield oil
+of the proper quality to be used as a cylinder lubricant.
+The crude petroleum is distilled as rapidly as possible
+with fire heat to vaporize off the naphthas and the burning
+oils. After these vapors have been given off superheated
+steam is provided to assist in distilling. When
+enough of the light elements have been eliminated the
+residue is drawn off, passed through a strainer to free
+it from grit and earthy matters, and is afterwards cooled
+to separate the wax from it. This is the dark cylinder oil
+and is the grade usually used for steam-engine cylinders.</p>
+
+<h3><a name="SecVII_5" id="SecVII_5"></a>PROPERTIES OF CYLINDER OILS</h3>
+
+<p>The oil that is to be used in the gasoline engine must
+be of high quality, and for that reason the best grades
+are distilled in a vacuum that the light distillates may be
+separated at much lower temperatures than ordinary
+conditions of distilling permit. If the degree of heat
+is not high the product is not so apt to decompose and
+deposit carbon. If it is desired to remove the color of
+the oil which is caused by free carbon and other impurities
+it can be accomplished by filtering the oil through charcoal.
+The greater the number of times the oil is filtered,<span class='pagenum'><a name="Page_207" id="Page_207">[207]</a></span>
+the lighter it will become in color. The best cylinder
+oils have flash points usually in excess of 500 degrees F.,
+and while they have a high degree of viscosity at 100
+degrees F. they become more fluid as the temperature
+increases.</p>
+
+<p>The lubricating oils obtained by refining crude petroleum
+may be divided into three classes:</p>
+
+<p>First&mdash;The natural oils of great body which are prepared
+for use by allowing the crude material to settle
+in tanks at high temperature and from which the impurities
+are removed by natural filtration. These oils are
+given the necessary body and are free from the volatile
+substances they contain by means of superheated steam
+which provides a source of heat.</p>
+
+<p>Second&mdash;Another grade of these natural oils which are
+filtered again at high temperatures and under pressure
+through beds of animal charcoal to improve their color.</p>
+
+<p>Third&mdash;Pale, limpid oils, obtained by distillation and
+subsequent chemical treatment from the residuum produced
+in refining petroleum to obtain the fuel oils.</p>
+
+<p>Authorities agree that any form of mixed oil in which
+animal and mineral lubricants are combined should never
+be used in the cylinder of a gas engine as the admixture
+of the lubricants does not prevent the decomposition of
+the organic oil into the glycerides and fatty acids peculiar
+to the fat used. In a gas-engine cylinder the flame tends
+to produce more or less charring. The deposits of carbon
+will be much greater with animal oils than with those
+derived from the petroleum base because the constituents
+of a fat or tallow are not of the same volatile character
+as those which comprise the hydro-carbon oils which will
+evaporate or volatilize before they char in most instances.</p>
+
+<h3><a name="SecVII_6" id="SecVII_6"></a>FACTORS INFLUENCING LUBRICATION SYSTEM SELECTION</h3>
+
+<p>The suitability of oil for the proper and efficient lubrication
+of all internal combustion engines is determined
+chiefly by the following factors:</p>
+
+<p><span class='pagenum'><a name="Page_208" id="Page_208">[208]</a></span>1. Type of cooling system (operating temperatures).</p>
+
+<p>2. Type of lubricating system (method of applying
+oil to the moving parts).</p>
+
+<p>3. Rubbing speeds of contact surfaces.</p>
+
+<p>Were the operating temperatures, bearing surface
+speeds and lubrication systems identical, a single oil
+could be used in all engines with equal satisfaction. The
+only change then necessary in viscosity would be that due
+to climatic conditions. As engines are now designed, only
+three grades of oil are necessary for the lubrication of
+all types with the exception of Knight, air-cooled and
+some engines which run continuously at full load. In the
+specification of engine lubricants the feature of load
+carried by the engine should be carefully considered.</p>
+
+<p><i>Full Load Engines.</i></p>
+
+<ol>
+<li>Marine.</li>
+<li>Racing automobile.</li>
+<li>Aviation.</li>
+<li>Farm tractor.</li>
+<li>Some stationary.</li>
+</ol>
+
+<p><i>Variable Load Engines.</i></p>
+
+<ol>
+<li>Pleasure automobile.</li>
+<li>Commercial vehicle.</li>
+<li>Motor cycle.</li>
+<li>Some stationary.</li>
+</ol>
+
+<p>Of the forms outlined, the only one we have any
+immediate concern about is the airplane power plant.
+The Platt &amp; Washburn Refining Company, who have
+made a careful study of the lubrication problem as applied
+to all types of engines, have found a peculiar set
+of conditions to apply to oiling high-speed constant-duty
+or &#8220;full-load&#8221; engines. Modern airplane engines are
+designed to operate continuously at a fairly uniform
+high rotative speed and at full load over long periods
+of time. As a sequence to this heavy duty the operating<span class='pagenum'><a name="Page_209" id="Page_209">[209]</a></span>
+temperatures are elevated. For the sake of extreme lightness
+in weight of all parts, very thin alloy steel aluminum
+or cast iron pistons are fitted and the temperature of
+the thin piston heads at the center reaches anywhere
+between <span class="nowrap">600&deg;</span> and <span class="nowrap">1,400&deg;</span> Fahr., as in automobile racing
+engines. Freely exposed to such intense heat hydro-carbon
+oils are partially &#8220;cracked&#8221; into light and heavy products
+or polymerized into solid hydro-carbons. From these
+facts it follows that only heavy mineral oils of low carbon
+residue and of the greatest chemical purity and stability
+should be used to secure good lubrication. In all cases
+the oil should be sufficiently heavy to assure the highest
+horse-power and fuel and oil economy compatible with
+perfect lubrication, avoiding, at the same time, carbonization
+and ignition failure. When aluminum pistons are
+used their superior heat-conducting properties aid materially
+in reducing the rate of oil destruction.</p>
+
+<p>The extraordinary evolutions described by airplanes
+in flight make it a matter of vital necessity to operate
+engines inclined at all angles to the vertical as well as in
+an upside-down position. To meet this situation lubricating
+systems have been elaborated so as to deliver
+an abundance of oil where needed and to eliminate possible
+flooding of cylinders. This is done by applying a
+full force feed system, distributing oil under considerable
+pressure to all working parts. Discharged through the
+bearings, the oil drains down to the suction side of a
+second pump located in the bottom of the base chamber.
+This pump being of greater capacity than the first prevents
+the accumulation of oil in the crank-case, and
+forces it to a separate oil reservoir-cooler, whence it
+flows back in rapid circulation to the pump feeding the
+bearings. With this arrangement positive lubrication
+is entirely independent of engine position. The lubricating
+system of the Thomas-Morse aviation engines,
+which is shown at <a href="#Fig076">Fig. 76</a>, is typical of current practice.</p>
+
+<p class='pagenum' style="margin-top: -1.5em;"><a name="Page_210" id="Page_210">[210]</a></p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig076" id="Fig076"></a>
+<img src="images/illo205.png" alt="Fig. 76" width="600" height="362" />
+<p class="caption">Fig. 76.&mdash;Pressure Feed Oiling System of Thomas Aviation Engine Includes Oil Cooling Means.</p></div>
+
+<p class='pagenum'><a name="Page_211" id="Page_211">[211]</a></p>
+
+<h3><a name="SecVII_7" id="SecVII_7"></a>GNOME TYPE ENGINES USE CASTOR OIL</h3>
+
+<p>The construction and operation of rotative radial
+cylinder engines introduce additional difficulties of lubrication
+to those already referred to and merit especial
+attention. Owing to the peculiar alimentation systems
+of Gnome type engines, atomized gasoline mixed with
+air is drawn through the hollow stationary crank-shaft
+directly into the crank-case which it fills on the way to
+the cylinders. Therein lies the trouble. Hydrocarbon
+oils are soon dissolved by the gasoline and washed off,
+leaving the bearing surfaces without adequate protection
+and exposed to instant wear and destruction. So castor
+oil is resorted to as an indispensable but unfortunate
+compromise. Of vegetable origin, it leaves a much more
+bulky carbon deposit in the explosion chambers than
+does mineral oil and its great affinity for oxygen causes
+the formation of voluminous gummy deposit in the crank-case.
+Engines employing it need to be dismounted and
+thoroughly scraped out at frequent intervals. It is advisable
+to use only unblended chemically pure castor oil
+in rotative engines, first by virtue of its insolubility in
+gasoline and second because its extra heavy body can
+resist the high temperature of air-cooled cylinders.</p>
+
+<h3><a name="SecVII_8" id="SecVII_8"></a>HALL-SCOTT LUBRICATION SYSTEM</h3>
+
+<p>The oiling system of the Hall-Scott type A-5 125
+horse-power engine is clearly shown at <a href="#Fig077">Fig. 77</a>. It is
+completely described in the instruction book issued by
+the company from which the following extracts are reproduced
+by permission. Crank-shaft, connecting rods and
+all other parts within the crank-case and cylinders are
+lubricated directly or indirectly by a force-feed oiling
+system. The cylinder walls and wrist pins are lubricated
+by oil spray thrown from the lower end of connecting
+rod bearings. This system is used only upon A-5 engines.
+Upon A-7a and A-5a engines a small tube supplies oil<span class='pagenum'><a name="Page_212" id="Page_212">[212]</a></span>
+from connecting rod bearing directly upon the wrist pin.
+The oil is drawn from the strainer located at the lowest
+portion of the lower crank-case, forced around the main
+intake manifold oil jacket. From here it is circulated
+to the main distributing pipe located along the lower left
+hand side of upper crank-case. The oil is then forced
+directly to the lower side of crank-shaft, through holes
+drilled in each main bearing cup. Leakage from these
+main bearings is caught in scuppers placed upon the
+cheeks of the crank-shafts furnishing oil under pressure
+to the connecting rod bearings. A-7a and A-5a engines
+have small tubes leading from these bearings which convey
+the oil under pressure to the wrist pins.</p>
+
+<p class='pagenum' style="margin-top: -1.5em;"><a name="Page_213" id="Page_213">[213]</a></p>
+
+<div class="figcenter" style="width: 650px;"><a name="Fig077" id="Fig077"></a>
+<img src="images/illo207.png" alt="Fig. 77" width="650" height="397" />
+<p class="caption">Fig. 77.&mdash;Diagram of Oiling System, Hall-Scott Type A 125 Horse-Power Engine.</p></div>
+
+<p>A bi-pass located at the front end of the distributing
+oil pipe can be regulated to lessen or raise the pressure.
+By screwing the valve in, the pressure will raise and
+more oil will be forced to the bearings. By unscrewing,
+pressure is reduced and less oil is fed. A-7a and A-5a
+engines have oil relief valves located just off of the main
+oil pump in the lower crank-case. This regulates the
+pressure at all times so that in cold weather there will
+be no danger of bursting oil pipes due to excessive pressure.
+If it is found the oil pressure is not maintained
+at a high enough level, inspect this valve. A stronger
+spring will not allow the oil to bi-pass so freely, and
+consequently the pressure will be raised; a weaker spring
+will bi-pass more oil and reduce the oil pressure materially.
+Independent of the above-mentioned system, a
+small, directly driven rotary oiler feeds oil to the base
+of each individual cylinder. The supply of oil is furnished
+by the main oil pump located in the lower crank-case.
+A small sight-feed regulator is furnished to control
+the supply of oil from this oiler. This instrument should
+be placed higher than the auxiliary oil distributor itself
+to enable the oil to drain by gravity feed to the oiler.
+If there is no available place with the necessary height
+in the front seat of plane, connect it directly to the intake
+L fitting on the oiler in an upright position. It should<span class='pagenum'><a name="Page_214" id="Page_214">[214]</a></span>
+be regulated with full open throttle to maintain an oil
+level in the glass, approximately half way.</p>
+
+<p>An oil pressure gauge is provided. This should be run
+to the pilot&#8217;s instrument board. The gauge registers the
+oil pressure upon the bearings, also determining its circulation.
+Strict watch should be maintained of this instrument
+by pilot, and if for any reason its hand should
+drop to 0 the motor should be immediately stopped and
+the trouble found before restarting engine. Care should
+be taken that the oil does not work up into the gauge,
+as it will prevent the correct gauge registering of oil
+pressure. The oil pressure will vary according to weather
+conditions and viscosity of oil used. In normal weather,
+with the engine properly warmed up, the pressure will
+register on the oil gauge from 5 to 10 pounds when the
+engine is turning from 1,275 to 1,300 r. p. m. This does
+not apply to all aviation engines, however, as the proper
+pressure advised for the Curtiss OX-2 motor is from 40
+to 55 pounds at the gauge.</p>
+
+<p>The oil sump plug is located at the lowest point of
+the lower crank-case. This is a combination dirt, water
+and sediment trap. It is easily removed by unscrewing.
+Oil is furnished mechanically to the cam-shaft housing
+under pressure through a small tube leading from the
+main distributing pipe at the propeller end of engine
+directly into the end of cam-shaft housing. The opposite
+end of this housing is amply relieved to allow the oil
+to rapidly flow down upon cam-shaft, magneto, pinion-shaft,
+and crank-shaft gears, after which it returns to
+lower crank-case. An outside overflow pipe is also provided
+to carry away the surplus oil.</p>
+
+<h3>DRAINING OIL FROM CRANK-CASE</h3>
+
+<p>The oil strainer is placed at the lowest point of the
+lower crank-case. This strainer should be removed after
+every five to eight hours running of the engine and
+cleaned thoroughly with gasoline. It is also advisable
+to squirt distillate up into the case through the opening<span class='pagenum'><a name="Page_215" id="Page_215">[215]</a></span>
+where the strainer has been removed. Allow this distillate
+to drain out thoroughly before replacing the plug
+with strainer attached. Be sure gasket is in place on
+plug before replacing. Pour new oil in through either
+of the two breather pipes on exhaust side of motor.
+Be sure to replace strainer screens if removed. If,
+through oversight, the engine does not receive sufficient
+lubrication and begins to heat or pound, it should be
+stopped immediately. After allowing engine to cool pour
+at least three gallons of oil into oil sump. Fill radiator
+with water after engine has cooled. Should there be
+apparent damage, the engine should be thoroughly inspected
+immediately without further running. If no obvious
+damage has been done, the engine should be given
+a careful examination at the earliest opportunity to see
+that the running without oil has not burned the bearings
+or caused other trouble.</p>
+
+<p>Oils best adapted for Hall-Scott engines have the following
+properties: A flash test of not less than <span class="nowrap">400&deg;</span> F.;
+viscosity of not less than 75 to 85 taken at <span class="nowrap">21&deg;</span> F. with
+Saybolt&#8217;s Universal Viscosimeter.</p>
+
+<p><i>Zeroline heavy duty oil</i>, manufactured by the Standard
+Oil Company of California; also,</p>
+
+<p><i>Gargoyle mobile B oil</i>, manufactured by the Vacuum
+Oil Company, both fulfill the above specifications. One
+or the other of these oils can be obtained all over the
+world.</p>
+
+<p>Monogram extra heavy is also recommended.</p>
+
+<h3><a name="SecVII_9" id="SecVII_9"></a>OIL SUPPLY BY CONSTANT LEVEL SPLASH SYSTEM</h3>
+
+<p>The splash system of lubrication that depends on the
+connecting rod to distribute the lubricant is one of the
+most successful and simplest forms for simple four- and
+six-cylinder vertical automobile engines, but is not as
+well adapted to the oiling of airplane power plants for
+reasons previously stated. If too much oil is supplied
+the surplus will work past the piston rings and into the
+combustion chamber, where it will burn and cause carbon<span class='pagenum'><a name="Page_216" id="Page_216">[216]</a></span>
+deposits. Too much oil will also cause an engine to smoke
+and an excess of lubricating oil is usually manifested
+by a bluish-white smoke issuing from the exhaust.</p>
+
+<p>A good method of maintaining a constant level of oil
+for the successful application of the splash system is
+shown at <a href="#Fig078">Fig. 78</a>. The engine base casting includes a
+separate chamber which serves as an oil container and
+which is below the level of oil in the crank-case. The
+lubricant is drawn from the sump or oil container by
+means of a positive oil pump which discharges directly
+into the engine case. The level is maintained by an overflow
+pipe which allows all excess lubricant to flow back
+into the oil container at the bottom of the cylinder.
+Before passing into the pump again the oil is strained
+or filtered by a screen of wire gauze and all foreign
+matter removed. Owing to the rapid circulation of the
+oil it may be used over and over again for quite a period
+of time. The oil is introduced directly into the crank-case
+by a breather pipe and the level is indicated by
+a rod carried by a float which rises when the container is
+replenished and falls when the available supply diminishes.
+It will be noted that with such system the only
+apparatus required besides the oil tank which is cast
+integral with the bottom of the crank-case is a suitable
+pump to maintain circulation of oil. This member is
+always positively driven, either by means of shaft and
+universal coupling or direct gearing. As the system is
+entirely automatic in action, it will furnish a positive
+supply of oil at all desired points, and it cannot be
+tampered with by the inexpert because no adjustments
+are provided or needed.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig078" id="Fig078"></a>
+<img src="images/illo212.png" alt="Fig. 78" width="400" height="516" />
+<p class="caption">Fig. 78.&mdash;Sectional View of Typical Motor Showing Parts Needing Lubrication
+and Method of Applying Oil by Constant Level Splash System.
+Note also Water Jacket and Spaces for Water Circulation.</p></div>
+
+<h3><a name="SecVII_10" id="SecVII_10"></a>DRY CRANK-CASE SYSTEM BEST FOR AIRPLANE ENGINES</h3>
+
+<p>In most airplane power plants it is considered desirable
+to supply the oil directly to the parts needing it by suitable
+leads instead of depending solely upon the distributing
+action of scoops on the connecting rod big ends.
+A system of this nature is shown at <a href="#Fig077">Fig. 77</a>. The
+oil<span class='pagenum'><a name="Page_217" id="Page_217">[217]</a></span>
+is carried in the crank-case, as is common practice, but
+the normal oil level is below the point where it will be
+reached by the connecting rod. It is drawn from the
+crank-case by a plunger pump which directs it to a manifold
+leading directly to conductors which supply the main<span class='pagenum'><a name="Page_218" id="Page_218">[218]</a></span>
+journals. After the oil has been used on these points it
+drains back into the bottom of the crank-case. An excess
+is provided which is supplied to the connecting rod ends
+by passages drilled into the webs of the crank-shaft and
+part way into the crank-pins as shown by the dotted
+lines. The oil which is present at the connecting rod
+crank-pins is thrown off by centrifugal force and lubricates
+the cylinder walls and other internal parts. Regulating
+screws are provided so that the amount of oil
+supplied the different points may be regulated at will.
+A relief check valve is installed to take care of excess
+lubricant and to allow any oil that does not pass back
+into the pipe line to overflow or bi-pass into the main
+container.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig079" id="Fig079"></a>
+<img src="images/illo213.png" alt="Fig. 79" width="450" height="367" />
+<p class="caption">Fig. 79.&mdash;Pressure Feed Oil-Supply System of Airplane Power Plants has
+Many Good Features.</p></div>
+
+<p>A simple system of this nature is shown graphically
+in a phantom view of the crank-case at <a href="#Fig079">Fig. 79</a>,
+in which<span class='pagenum'><a name="Page_219" id="Page_219">[219]</a></span>
+the oil passages are made specially prominent. The oil
+is taken from a reservoir at the bottom of the engine
+base by the usual form of gear oil pump and is supplied
+to a main feed manifold which extends the length of the
+crank-case. Individual conductors lead to the five main
+bearings, which in turn supply the crank-pins by passages
+drilled through the crank-shaft web. In this power
+plant the connecting rods are hollow section bronze
+castings and the passage through the center of the connecting
+rod serves to convey the lubricant from the
+crank-pins to the wrist-pins. The cylinder walls are oiled
+by the spray of lubricant thrown off the revolving crank-shaft
+by centrifugal force. Oil projection by the dippers
+on the connecting rod ends from constant level troughs
+is unequal upon the cylinder walls of the two-cylinder
+blocks of an eight- or twelve-cylinder V engine. This
+gives rise, on one side of the engine, to under-lubrication,
+and, on the other side, to over-lubrication, as shown at
+<a href="#Fig080">Fig. 80</a>, A. This applies to all modifications of splash
+lubricating systems.</p>
+
+<p class='pagenum'><a name="Page_220" id="Page_220">[220]</a></p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig080" id="Fig080"></a>
+<img src="images/illo215.png" alt="Fig. 80" width="400" height="565" />
+<p class="caption">Fig. 80.&mdash;Why Pressure Feed System is Best for Eight-Cylinder Vee
+Airplane Engines.</p></div>
+
+<p>When a force-feed lubricating system is used, the oil,
+escaping past the cheeks of both ends of the crank-pin
+bearings, is thrown off at a tangent to the crank-pin
+circle in all directions, supplying the cylinders on both
+sides with an equal quantity of oil, as at <a href="#Fig080">Fig. 80</a>, B.</p>
+
+<h3><a name="SecVII_11" id="SecVII_11"></a>WHY COOLING SYSTEMS ARE NECESSARY</h3>
+
+<p>The reader should understand from preceding chapters
+that the power of an internal-combustion motor is
+obtained by the rapid combustion and consequent expansion
+of some inflammable gas. The operation in
+brief is that when air or any other gas or vapor is
+heated, it will expand and that if this gas is confined
+in a space which will not permit expansion, pressure will
+be exerted against all sides of the containing chamber.
+The more a gas is heated, the more pressure it will
+exert upon the walls of the combustion chamber it<span class='pagenum'><a name="Page_221" id="Page_221">[221]</a></span>
+confines. Pressure in a gas may be created by increasing
+its temperature and inversely heat may be created by
+pressure. When a gas is compressed its total volume is
+reduced and the temperature is augmented.</p>
+
+<p>The efficiency of any form of heat engine is determined
+by the power obtained from a certain fuel consumption.
+A definite amount of energy will be liberated
+in the form of heat when a pound of any fuel is burned.
+The efficiency of any heat engine is proportional to the
+power developed from a definite quantity of fuel with the
+least loss of thermal units. If the greater proportion
+of the heat units derived by burning the explosive mixture
+could be utilized in doing useful work, the efficiency
+of the gasoline engine would be greater than that of
+any other form of energizing power. There is a great
+loss of heat from various causes, among which can be
+cited the reduction of pressure through cooling the motor
+and the loss of heat through the exhaust valves when
+the burned gases are expelled from the cylinder.</p>
+
+<p>The loss through the water jacket of the average automobile
+power plant is over 50 per cent. of the total fuel
+efficiency. This means that more than half of the heat
+units available for power are absorbed and dissipated
+by the cooling water. Another 16 per cent. is lost through
+the exhaust valve, and but 33<sup>1</sup>&#8260;<sub>3</sub> per cent. of the heat
+units do useful work. The great loss of heat through
+the cooling systems cannot be avoided, as some method
+must be provided to keep the temperature of the engine
+within proper bounds. It is apparent that the rapid
+combustion and continued series of explosions would
+soon heat the metal portions of the engine to a red heat
+if some means were not taken to conduct much of this
+heat away. The high temperature of the parts would
+burn the lubricating oil, even that of the best quality,
+and the piston and rings would expand to such a degree,
+especially when deprived of oil, that they would seize in
+the cylinder. This would score the walls, and the friction
+which ensued would tend to bind the parts so tightly<span class='pagenum'><a name="Page_222" id="Page_222">[222]</a></span>
+that the piston would stick, bearings would be burned
+out, the valves would warp, and the engine would soon
+become inoperative.</p>
+
+<div class="figcenter" style="width: 550px;"><a name="Fig081" id="Fig081"></a>
+<img src="images/illo217.png" alt="Fig. 81" width="550" height="424" />
+<p class="caption">Fig. 81.&mdash;Operating Temperatures of Automobile Engine Parts Useful as a
+Guide to Understand Airplane Power Plant Heat.</p></div>
+
+<p>The best temperature to secure efficient operation is
+one on which considerable difference of opinion exists
+among engineers. The fact that the efficiency of an
+engine is dependent upon the ratio of heat converted
+into useful work compared to that generated by the
+explosion of the gas is an accepted fact. It is very
+important that the engine should not get too hot, and
+on the other hand it is equally vital that the cylinders
+be not robbed of too much heat. The object of cylinder
+cooling is to keep the temperature of the cylinder below
+the danger point, but at the same time to have it as
+high as possible to secure maximum power from the
+gas burned. The usual operating temperatures of an<span class='pagenum'><a name="Page_223" id="Page_223">[223]</a></span>
+automobile engine are shown at <a href="#Fig081">Fig. 81</a>, and this can
+be taken as an approximation of the temperatures apt to
+exist in an airplane engine of conventional design as well
+when at ground level or not very high in the air. The
+newer very high compression airplane engines in which
+compressions of eight or nine atmospheres are used, or
+about 125 pounds per square inch, will run considerably
+hotter than the temperatures indicated.</p>
+
+<h3><a name="SecVII_12" id="SecVII_12"></a>COOLING SYSTEMS GENERALLY APPLIED</h3>
+
+<p>There are two general systems of engine cooling in
+common use, that in which water is heated by the absorption
+of heat from the engine and then cooled by air,
+and the other method in which the air is directed onto
+the cylinder and absorbs the heat directly instead of
+through the medium of water. When the liquid is employed
+in cooling it is circulated through jackets which
+surround the cylinder casting and the water may be
+kept in motion by two methods. The one generally
+favored is to use a positive circulating pump of some
+form which is driven by the engine to keep the water
+in motion. The other system is to utilize a natural
+principle that heated water is lighter than cold liquid
+and that it will tend to rise to the top of the cylinder
+when it becomes heated to the proper temperature and
+cooled water takes its place at the bottom of the water
+jacket.</p>
+
+<p>Air-cooling methods may be by radiation or convection.
+In the former case the effective outer surface of
+the cylinder is increased by the addition of flanges
+machined or cast thereon, and the air is depended on
+to rise from the cylinder as heated and be replaced by
+cooler air. This, of course, is found only on stationary
+engines. When a positive air draught is directed against
+the cylinder by means of the propeller slip stream in
+an airplane, cooling is by convection and radiation both.
+Sometimes the air draught may be directed against the<span class='pagenum'><a name="Page_224" id="Page_224">[224]</a></span>
+cylinder walls by some form of jacket which confines it
+to the heated portions of the cylinder.</p>
+
+<h3><a name="SecVII_13" id="SecVII_13"></a>COOLING BY POSITIVE WATER CIRCULATION</h3>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig082" id="Fig082"></a>
+<img src="images/illo219.png" alt="Fig. 82" width="500" height="318" />
+<p class="caption">Fig. 82.&mdash;Water Cooling of Salmson Seven-Cylinder Radial Airplane Engine.</p></div>
+
+<p>A typical water-cooling system in which a pump is
+depended upon to promote circulation of the cooling
+liquid is shown at <a href="#Fig082">Figs. 82</a> and <a href="#Fig083">83</a>. The radiator is carried
+at the front end of the fuselage in most cases, and
+serves as a combined water tank and cooler, but in some
+cases it is carried at the side of the engine, as in <a href="#Fig084">Fig.
+84</a>, or attached to the central portion of the aerofoil or
+wing structure. It is composed of an upper and lower
+portion joined together by a series of pipes which may
+be round and provided with a series of fins to radiate
+the heat, or which may be flat in order to have the water
+pass through in thin sheets and cool it more easily.
+Cellular or honeycomb coolers are composed of a large
+number of bent tubes which will expose a large area of
+surface to the cooling influence of the air draught forced
+through the radiator either by the forward movement
+of the vehicle or by some type of fan. The cellular and<span class='pagenum'><a name="Page_225" id="Page_225">[225]</a></span>
+flat tube types have almost entirely displaced the flange
+tube radiators which were formerly popular because they
+cool the water more effectively, and may be made lighter
+than the tubular radiator could be for engines of the
+same capacity.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig083" id="Fig083"></a>
+<img src="images/illo220.jpg" alt="Fig. 83" width="500" height="424" />
+<p class="caption">Fig. 83.&mdash;How Water Cooling System of Thomas Airplane Engine is
+Installed in Fuselage.</p></div>
+
+<p>The water is drawn from the lower header of the
+radiator by the pump and is forced through a manifold
+to the lower portion of the water jackets of the cylinder.
+It becomes heated as it passes around the cylinder walls
+and combustion chambers and the hot water passes out
+of the top of the water jacket to the upper portion of
+the radiator. Here it is divided in thin streams and
+directed against comparatively cool metal which abstracts
+the heat from the water. As it becomes cooler it falls
+to the bottom of the radiator because its weight increases
+as the temperature becomes lower. By the time it reaches<span class='pagenum'><a name="Page_226" id="Page_226">[226]</a></span>
+the lower tank of the radiator it has been cooled sufficiently
+so that it may be again passed around the cylinders
+of the motor. The popular form of circulating
+pump is known as the &#8220;centrifugal type&#8221; because a rotary
+impeller of paddle-wheel form throws water which it
+receives at a central point toward the outside and thus
+causes it to maintain a definite rate of circulation. The
+pump is always a separate appliance attached to the
+engine and driven by positive gearing or direct-shaft
+connection. The centrifugal pump is not as positive as
+the gear form, and some manufacturers prefer the latter
+because of the positive pumping features. They are
+very simple in form, consisting of a suitable cast body
+in which a pair of spur pinions having large teeth are
+carried. One of these gears is driven by suitable means,
+and as it turns the other member they maintain a flow
+of water around the pump body. The pump should always
+be installed in series with the water pipe which<span class='pagenum'><a name="Page_227" id="Page_227">[227]</a></span>
+conveys the cool liquid from the lower compartment of the
+radiator to the coolest portion of the water jacket.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig084" id="Fig084"></a>
+<img src="images/illo221.jpg" alt="Fig. 84" width="500" height="352" />
+<p class="caption">Fig. 84.&mdash;Finned Tube Radiators at the Side of Hall-Scott Airplane Power
+Plant Installed in Standard Fuselage.</p></div>
+
+<h3><a name="SecVII_14" id="SecVII_14"></a>WATER CIRCULATION BY NATURAL SYSTEM</h3>
+
+<p>Some automobile engineers contend that the rapid
+water circulation obtained by using a pump may cool
+the cylinders too much, and that the temperature of the
+engine may be reduced so much that the efficiency will
+be lessened. For this reason there is a growing tendency
+to use the natural method of water circulation as the
+cooling liquid is supplied to the cylinder jackets just
+below the boiling point and the water issues from the
+jacket at the top of the cylinder after it has absorbed
+sufficient heat to raise it just about to the boiling point.</p>
+
+<p>As the water becomes heated by contact with the hot
+cylinder and combustion-chamber walls it rises to the top
+of the water jacket, flows to the cooler, where enough
+of the heat is absorbed to cause it to become sensibly
+greater in weight. As the water becomes cooler, it falls
+to the bottom of the radiator and it is again supplied
+to the water jacket. The circulation is entirely automatic
+and continues as long as there is a difference in temperature
+between the liquid in the water spaces of the
+engine and that in the cooler. The circulation becomes
+brisker as the engine becomes hotter and thus the temperature
+of the cylinders is kept more nearly to a fixed
+point. With the thermosyphon system the cooling liquid
+is nearly always at its boiling point, whereas if the circulation
+is maintained by a pump the engine will become
+cooler at high speed and will heat up more at low speed.</p>
+
+<p>With the thermosyphon, or natural system of cooling,
+more water must be carried than with the pump-maintained
+circulation methods. The water spaces around
+the cylinders should be larger, the inlet and discharge
+water manifolds should have greater capacity, and be
+free from sharp corners which might impede the flow.
+The radiator must also carry more water than the form
+used in connection with the pump because of the brisker<span class='pagenum'><a name="Page_228" id="Page_228">[228]</a></span>
+pump circulation which maintains the engine temperature
+at a lower point. Consideration of the above will show
+why the pump system is almost universally used in
+connection with airplane power plant cooling.</p>
+
+<h3><a name="SecVII_15" id="SecVII_15"></a>DIRECT AIR-COOLING METHODS</h3>
+
+<p>The earliest known method of cooling the cylinder
+of gas-engines was by means of a current of air passed
+through a jacket which confined it close to the cylinder
+walls and was used by Daimler on his first gas-engine.
+The gasoline engine of that time was not as efficient as
+the later form, and other conditions which materialized
+made it desirable to cool the engine by water. Even as
+gasoline engines became more and more perfected there
+has always existed a prejudice against air cooling, though
+many forms of engines have been used, both in automobile
+and aircraft applications where the air-cooling method
+has proven to be very practical.</p>
+
+<p>The simplest system of air cooling is that in which
+the cylinders are provided with a series of flanges which
+increase the effective radiating surface of the cylinder
+and directing an air-current from a fan against the
+flanges to absorb the heat. This increase in the available
+radiating surface of an air-cooled cylinder is necessary
+because air does not absorb heat as readily as water
+and therefore more surface must be provided that the
+excess heat be absorbed sufficiently fast to prevent distortion
+of the cylinders. Air-cooling systems are based
+on a law formulated by Newton, which is: &#8220;The rate for
+cooling for a body in a uniform current of air is directly
+proportional to the speed of the air current and the
+amount of radiating surface exposed to the cooling
+effect.&#8221;</p>
+
+<h3><a name="SecVII_16" id="SecVII_16"></a>AIR-COOLED ENGINE DESIGN CONSIDERATIONS</h3>
+
+<p>There are certain considerations which must be taken
+into account in designing an air-cooled engine, which are
+often overlooked in those forms cooled by water. Large<span class='pagenum'><a name="Page_229" id="Page_229">[229]</a></span>
+valves must be provided to insure rapid expulsion of
+the flaming exhaust gas and also to admit promptly the
+fresh cool mixture from the carburetor. The valves of
+air-cooled engines are usually placed in the cylinder-head,
+in order to eliminate any pockets or sharp passages
+which would impede the flow of gas or retain some of
+the products of combustion and their heat. When high
+power is desired multiple-cylinder engines should be used,
+as there is a certain limit to the size of a successful<span class='pagenum'><a name="Page_230" id="Page_230">[230]</a></span>
+air-cooled cylinder. Much better results are secured from
+those having small cubical contents because the heat from
+small quantities of gas will be more quickly carried off
+than from greater amounts. All successful engines of
+the aviation type which have been air-cooled have been
+of the multiple-cylinder type.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig085" id="Fig085"></a>
+<img src="images/illo224.jpg" alt="Fig. 85" width="400" height="438" />
+<p class="caption">Fig. 85.&mdash;Anzani Testing His Five-Cylinder Air Cooled Aviation Motor
+Installed in Bleriot Monoplane. Note Exposure of Flanged Cylinders
+to Propeller Slip Stream.</p></div>
+
+<p>An air-cooled engine must be placed in the fuselage,
+as at <a href="#Fig085">Fig. 85</a>, in such a way that there will be a positive
+circulation of air around it all the time that it is in
+operation. The air current may be produced by the
+tractor screw at the front end of the motor, or by a
+suction or blower fan attached to the crank-shaft as in the
+Renault engine or by rotating the cylinders as in the
+Le Rhone and Gnome motors. Greater care is required
+in lubrication of the air-cooled cylinders and only the best
+quality of oil should be used to insure satisfactory oiling.</p>
+
+<p>The combustion chambers must be proportioned so
+that distribution of metal is as uniform as possible in
+order to prevent uneven expansion during increase in
+temperature and uneven contraction when the cylinder
+is cooled. It is essential that the inside walls of the
+combustion chamber be as smooth as possible because
+any sharp angle or projection may absorb sufficient heat
+to remain incandescent and cause trouble by igniting the
+mixture before the proper time. The best grades of cast
+iron or steel should be used in the cylinder and piston
+and the machine work must be done very accurately
+so the piston will operate with minimum friction in the
+cylinder. The cylinder bore should not exceed 4<sup>1</sup>&#8260;<sub>2</sub> or 5
+inches and the compression pressure should never exceed
+75 pounds absolute, or about five atmospheres, or serious
+overheating will result.</p>
+
+<p>As an example of the care taken in disposing of the
+exhaust gases in order to obtain practical air-cooling,
+some cylinders are provided with a series of auxiliary
+exhaust ports uncovered by the piston when it reaches
+the end of its power stroke. The auxiliary exhaust ports
+open just as soon as the full force of the explosion has<span class='pagenum'><a name="Page_231" id="Page_231">[231]</a></span>
+been spent and a portion of the flaming gases is discharged
+through the ports in the bottom of the cylinder.
+Less of the exhaust gases remains to be discharged
+through the regular exhaust member in the cylinder-head
+and this will not heat the walls of the cylinder nearly
+as much as the larger quantity of hot gas would. That
+the auxiliary exhaust port is of considerable value is
+conceded by many designers of fixed and fan-shaped air-cooled
+motors for airplanes.</p>
+
+<p>Among the advantages stated for direct air cooling,
+the greatest is the elimination of cooling water and its
+cooling auxiliaries, which is a factor of some moment,
+as it permits considerable reduction in horse-power-weight
+ratio of the engine, something very much to be desired.
+In the temperate zone, where the majority of airplanes
+are used, the weather conditions change in a very few
+months from the warm summer to the extreme cold
+winter, and when water-cooled systems are employed it is
+necessary to add some chemical substance to the water
+to prevent it from freezing. The substances commonly
+employed are glycerine, wood alcohol, or a saturated
+solution of calcium chloride. Alcohol has the disadvantage
+in that it vaporizes readily and must be often renewed.
+Glycerine affects the rubber hose, while the
+calcium chloride solution crystallizes and deposits salt
+in the radiator and water pipes.</p>
+
+<p>One of the disadvantages of an air-cooling method,
+as stated by those who do not favor this system, is that
+engines cooled by air cannot be operated for extended
+periods under constant load or at very high speed without
+heating up to such a point that premature ignition
+of the charge may result. The water-cooling systems,
+at the other hand, maintain the temperature of the engine
+more nearly constant than is possible with an air-cooled
+motor, and an engine cooled by water can be operated
+under conditions of inferior lubrication or poor mixture
+adjustment that would seriously interfere with proper
+and efficient cooling by air.</p>
+
+<p><span class='pagenum'><a name="Page_232" id="Page_232">[232]</a></span>Air-cooled motors, as a rule, use less fuel than water-cooled
+engines, because the higher temperature of the
+cylinder does not permit of a full charge of gas being
+inspired on the intake stroke. As special care is needed
+in operating an air-cooled engine to obtain satisfactory
+results and because of the greater difficulty which obtains
+in providing proper lubrication and fuel mixtures which
+will not produce undue heating, the air-cooled system
+has but few adherents at the present time, and practically
+all airplanes, with but very few exceptions, are provided
+with water-cooled power plants. Those fitted with air-cooled
+engines are usually short-flight types where maximum
+lightness is desired in order to obtain high speed
+and quick climb. The water-cooled engines are best
+suited for airplanes intended for long flights. The Gnome,
+Le Rhone and Clerget engines are thoroughly practical
+and have been widely used in France and England.
+These are rotary radial cylinder types. The Anzani is
+a fixed cylinder engine used on training machines, while
+the Renault is a V-type engine made in eight- and twelve-cylinder
+V forms that has been used on reconnaissance
+and bombing airplanes with success. These types will
+be fully considered in proper sequence.</p>
+
+<hr class="c25" />
+<p class='pagenum'><a name="Page_233" id="Page_233">[233]</a></p>
+<h2><a name="ChVIII" id="ChVIII"></a>CHAPTER VIII</h2>
+
+<p><a href="#SecVIII_1">Methods of Cylinder Construction</a>&mdash;<a href="#SecVIII_2">Block Castings</a>&mdash;<a
+href="#SecVIII_3">Influence on Crank-Shaft Design</a>&mdash;<a href="#SecVIII_4">Combustion Chamber Design</a>&mdash;<a
+href="#SecVIII_5">Bore and Stroke Ratio</a>&mdash;<a href="#SecVIII_6">Meaning of Piston Speed</a>&mdash;<a href="#SecVIII_7">Advantage of
+Off-Set Cylinders</a>&mdash;<a href="#SecVIII_8">Valve Location of Vital Import</a>&mdash;<a href="#SecVIII_9">Valve Installation
+Practice</a>&mdash;<a href="#SecVIII_10">Valve Design and Construction</a>&mdash;<a href="#SecVIII_11">Valve Operation</a>&mdash;<a
+href="#SecVIII_12">Methods of Driving Cam-Shaft</a>&mdash;<a href="#SecVIII_13">Valve Springs</a>&mdash;<a href="#SecVIII_14">Valve
+Timing</a>&mdash;<a href="#SecVIII_15">Blowing Back</a>&mdash;<a href="#SecVIII_16">Lead Given Exhaust Valve</a>&mdash;<a
+href="#SecVIII_17">Exhaust Closing, Inlet Opening</a>&mdash;<a href="#SecVIII_18">Closing the Inlet Valve</a>&mdash;<a
+href="#SecVIII_19">Time of Ignition</a>&mdash;<a href="#SecVIII_20">How an Engine Is Timed</a>&mdash;<a href="#SecVIII_21">Gnome
+&#8220;Monosoupape&#8221; Valve Timing</a>&mdash;<a href="#SecVIII_22">Springless Valves</a>&mdash;<a href="#SecVIII_23">Four Valves per
+Cylinder.</a></p>
+
+<p>The improvements noted in the modern internal combustion
+motors have been due to many conditions. The
+continual experimenting by leading mechanical minds
+could have but one ultimate result. The parts of the
+engines have been lightened and strengthened, and greater
+power has been obtained without increasing piston displacement.
+A careful study has been made of the many
+conditions which make for efficient motor action, and
+that the main principles are well recognized by all engineers
+is well shown by the standardization of design
+noted in modern power plants. There are many different
+methods of applying the same principle, and it will be
+the purpose of this chapter to define the ways in which
+the construction may be changed and still achieve the
+same results. The various components may exist in many
+different forms, and all have their advantages and disadvantages.
+That all methods are practical is best shown
+by the large number of successful engines which use
+radically different designs.</p>
+
+<h3><a name="SecVIII_1" id="SecVIII_1"></a>METHODS OF CYLINDER CONSTRUCTION</h3>
+
+<p>One of the most important parts of the gasoline
+engine and one that has material bearing upon its efficiency
+is the cylinder unit. The cylinders may be cast<span class='pagenum'><a name="Page_234" id="Page_234">[234]</a></span>
+individually, or in pairs, and it is possible to make all
+cylinders a unit or block casting. Some typical methods
+of cylinder construction are shown in accompanying illustrations.
+The appearance of individual cylinder castings
+may be ascertained by examination of the Hall-Scott
+airplane engine. Air-cooled engine cylinders are always
+of the individual pattern.</p>
+
+<p>Considered from a purely theoretical point of view,
+the individual cylinder casting has much in its favor.
+It is advanced that more uniform cooling is possible
+than where the cylinders are cast either in pairs or three
+or four in one casting. More uniform cooling insures
+that the expansion or change of form due to heating will
+be more equal. This is an important condition because
+the cylinder bore must remain true under all conditions
+of operation. If the heating effect is not uniform, which
+condition is liable to obtain if metal is not evenly distributed,
+the cylinder may become distorted by heat and
+the bore be out of truth. When separate cylinders are
+used it is possible to make a uniform water space and
+have the cooling liquid evenly distributed around the
+cylinder. In multiple cylinder castings this is not always
+the rule, as in many instances, especially in four-cylinder
+block motors where compactness is the main feature, there
+is but little space between the cylinders for the passage
+of water. Under such circumstances the cooling effect
+is not even, and the stresses which obtain because of
+unequal expansion may distort the cylinder to some
+extent. When steel cylinders are made from forgings,
+the water jackets are usually of copper or sheet steel
+attached to the forging by autogenous welding; in the
+case of the latter and, in some cases, the former may be
+electro-deposited on the cylinders.</p>
+
+<h3><a name="SecVIII_2" id="SecVIII_2"></a>BLOCK CASTINGS</h3>
+
+<p>The advantage of casting the cylinders in blocks is
+that a motor may be much shorter than it would be if
+individual castings were used. It is admitted that when<span class='pagenum'><a name="Page_235" id="Page_235">[235]</a></span>
+the cylinders are cast together a more compact, rigid,
+and stronger power plant is obtained than when cast
+separately. There is a disadvantage, however, in that
+if one cylinder becomes damaged it will be necessary to
+replace the entire unit, which means scrapping three
+good cylinders because one of the four has failed. When
+the cylinders are cast separately one need only replace
+the one that has become damaged. The casting of four
+cylinders in one unit is made possible by improved<span class='pagenum'><a name="Page_236" id="Page_236">[236]</a></span>
+foundry methods, and when proper provision is made for
+holding the cores when the metal is poured and the
+cylinder casts are good, the construction is one of distinct
+merit. It is sometimes the case that the proportion
+of sound castings is less when cylinders are cast in
+block, but if the proper precautions are observed in
+molding and the proper mixtures of cast iron used, the
+ratio of defective castings is no more than when cylinders
+are molded individually. As an example of the courage
+of engineers in departing from old-established rules, the
+cylinder casting shown at <a href="#Fig086">Fig. 86</a> may be considered
+typical. This is used on the Duesenberg four-cylinder
+sixteen-valve <span class="nowrap">4<sup>3</sup>&#8260;<sub>4</sub>&#8242;&#8242;</span>
+&times; <span class="nowrap">7&#8242;&#8242;</span> engine which has a piston displacement
+of 496 cu. in. At a speed of 2,000 r.p.m.,
+corresponding to a piston speed of 2,325 ft. per min., the
+engine is guaranteed to develop 125 horse-power. The
+weight of the model engine without gear reduction is
+436 lbs., but a number of refinements have been made in
+the design whereby it is expected to get the weight down
+to 390 lbs. The four cylinders are cast from semi-steel
+in a single block, with integral heads. The cylinder
+construction is the same as that which has always
+been used by Mr. Duesenberg, inlet and exhaust valves
+being arranged horizontally opposite each other in the
+head. There are large openings in the water jacket
+at both sides and at the ends, which are closed by means
+of aluminum covers, water-tightness being secured by
+the use of gaskets. This results in a saving in weight
+because the aluminum covers can be made considerably
+lighter than it would be possible to cast the jacket walls,
+and, besides, it permits of obtaining a more nearly uniform
+thickness of cylinder wall, as the cores can be
+much better supported. The cooling water passes completely
+around each cylinder, and there is a very considerable
+space between the two central cylinders, this
+being made necessary in order to get the large bearing
+area desirable for the central bearing.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig086" id="Fig086"></a>
+<img src="images/illo230.png" alt="Fig. 86" width="400" height="463" />
+<p class="caption">Fig. 86.&mdash;Views of Four-Cylinder Duesenberg Airplane Engine
+Cylinder Block.</p></div>
+
+<p>It is common practice to cast the water jackets integral<span class='pagenum'><a name="Page_237" id="Page_237">[237]</a></span>
+with the cylinders, if cast iron or aluminum is used,
+and this is also the most economical method of applying
+it because it gives good results in practice. An important
+detail is that the water spaces must be proportioned so
+that they are equal around the cylinders whether these
+members are cast individually, in pairs, threes or fours.
+When cylinders are cast in block form it is good practice
+to leave a large opening in the jacket wall which will
+assist in supporting the core and make for uniform water
+space. It will be noticed that the casting shown at <a href="#Fig086">Fig.
+86</a> has a large opening in the side of the cylinder block.
+These openings are closed after the interior of the casting
+is thoroughly cleaned of all sand, core wire, etc., by brass,
+cast iron or aluminum plates. These also have particular
+value in that they may be removed after the motor has
+been in use, thus permitting one to clean out the interior
+of the water jacket and dispose of the rust, sediment,
+and incrustation which are always present after the
+engine has been in active service for a time.</p>
+
+<p>Among the advantages claimed for the practice of
+casting cylinders in blocks may be mentioned compactness,
+lightness, rigidity, simplicity of water piping, as well
+as permitting the use of simple forms of inlet and exhaust
+manifolds. The light weight is not only due to the reduction
+of the cylinder mass but because the block construction
+permits one to lighten the entire motor. The fact
+that all cylinders are cast together decreases vibration,
+and as the construction is very rigid, disalignment of
+working parts is practically eliminated. When inlet and
+exhaust manifolds are cored in the block casting, as is
+sometimes the case, but one joint is needed on each of
+these instead of the multiplicity of joints which obtain
+when the cylinders are individual castings. The water
+piping is also simplified. In the case of a four-cylinder
+block motor but two pipes are used; one for the water
+to enter the cylinder jacket, the other for the cooling
+liquid to discharge through.</p>
+
+<p class='pagenum'><a name="Page_238" id="Page_238">[238]</a></p>
+
+<h3><a name="SecVIII_3" id="SecVIII_3"></a>INFLUENCE ON CRANK-SHAFT DESIGN</h3>
+
+<p>The method of casting the cylinders has a material
+influence on the design of the crank-shaft as will be shown
+in proper sequence. When four cylinders are combined
+in one block it is possible to use a two-bearing crank-shaft.
+Where cylinders are cast in pairs a three-bearing crank-shaft
+is commonly supplied, and when cylinders are cast
+as individual units it is thought necessary to supply a
+five-bearing crank-shaft, though sometimes shafts having
+but three journals are used successfully. Obviously the
+shafts must be stronger and stiffer to withstand the
+stresses imposed if two supporting bearings are used
+than if a larger number are employed. In this connection
+it may be stated that there is less difficulty in securing
+alignment with a lesser number of bearings and there
+is also less friction. On the other hand, the greater the
+number of points of support a crank-shaft has the lighter
+the webs can be made and still have requisite strength.</p>
+
+<p class='pagenum'><a name="Page_239" id="Page_239">[239]</a></p>
+
+<h3><a name="SecVIII_4" id="SecVIII_4"></a>COMBUSTION CHAMBER DESIGN</h3>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig087" id="Fig087"></a>
+<img src="images/illo233.png" alt="Fig. 87" width="500" height="355" />
+<p class="caption">Fig. 87.&mdash;Twin-Cylinder Block of Sturtevant Airplane Engine is Cast of
+Aluminum, and Has Removable Cylinder Head.</p></div>
+
+<p>Another point of importance in the design of the cylinder,
+and one which has considerable influence upon the
+power developed, is the shape of the combustion chamber.
+The endeavor of designers is to obtain maximum power
+from a cylinder of certain proportions, and the greater
+energy obtained without increasing piston displacement
+or fuel consumption the higher the efficiency of the motor.
+To prevent troubles due to pre-ignition it is necessary
+that the combustion chamber be made so that there will
+be no roughness, sharp corners, or edges of metal which
+may remain incandescent when heated or which will serve
+to collect carbon deposits by providing a point of anchorage.
+With the object of providing an absolutely clean
+combustion chamber some makers use a separable head
+unit to their twin cylinder castings, such as shown at
+<a href="#Fig087">Fig. 87</a> and <a href="#Fig088">Fig. 88</a>. These permit one to machine the
+entire interior of the cylinder and combustion chamber.
+The relation of valve location and combustion chamber
+design will be considered in proper sequence. These
+cylinders are cast of aluminum, instead of cast iron, as<span class='pagenum'><a name="Page_240" id="Page_240">[240]</a></span>
+is customary, and are provided with steel or cast iron
+cylinder liners forced in the soft metal casting bores.</p>
+
+<div class="figcenter" style="width: 550px;"><a name="Fig088" id="Fig088"></a>
+<img src="images/illo234.jpg" alt="Fig. 88" width="550" height="315" />
+<p class="caption">Fig. 88.&mdash;Aluminum Cylinder Pair Casting of Thomas 150 Horse-Power
+Airplane Engine is of the L Head Type.</p></div>
+
+<h3><a name="SecVIII_5" id="SecVIII_5"></a>BORE AND STROKE RATIO</h3>
+
+<p>A question that has been a vexed one and which has
+been the subject of considerable controversy is the proper
+proportion of the bore to the stroke. The early gas engines
+had a certain well-defined bore to stroke ratio, as
+it was usual at that time to make the stroke twice as long
+as the bore was wide, but this cannot be done when high
+speed is desired. With the development of the present-day
+motor the stroke or piston travel has been gradually
+shortened so that the relative proportions of bore and
+stroke have become nearly equal. Of late there seems to
+be a tendency among designers to return to the proportions
+which formerly obtained, and the stroke is sometimes
+one and a half or one and three-quarter times the
+bore.</p>
+
+<p>Engines designed for high speed should have the stroke
+not much longer than the diameter of the bore. The disadvantage
+of short-stroke engines is that they will not
+pull well at low speeds, though they run with great regularity
+and smoothness at high velocity. The long-stroke
+engine is much superior for slow speed work, and it will
+pull steadily and with increasing power at low speed.
+It was formerly thought that such engines should never
+turn more than a moderate number of revolutions, in
+order not to exceed the safe piston speed of 1,000 feet
+per minute. This old theory or rule of practice has been
+discarded in designing high efficiency automobile racing
+and aviation engines, and piston speeds from 2,500 to
+3,000 feet per minute are sometimes used, though the
+average is around 2,000 feet per minute. While both
+short- and long-stroke motors have their advantages, it
+would seem desirable to average between the two. That
+is why a proportion of four to five or six seems to be
+more general than that of four to seven or eight, which
+would be a long-stroke ratio. Careful analysis of a number<span class='pagenum'><a name="Page_241" id="Page_241">[241]</a></span>
+of foreign aviation motors shows that the average
+stroke is about 1.2 times the bore dimensions, though
+some instances were noted where it was as high as 1.7
+times the bore.</p>
+
+<h3><a name="SecVIII_6" id="SecVIII_6"></a>MEANING OF PISTON SPEED</h3>
+
+<p>The factor which limits the stroke and makes the
+speed of rotation so dependent upon the travel of the
+piston is piston speed. Lubrication is the main factor
+which determines piston speed, and the higher the rate
+of piston travel the greater care must be taken to insure
+proper oiling. Let us fully consider what is meant by
+piston speed.</p>
+
+<p>Assume that a motor has a piston travel or stroke of
+six inches, for the sake of illustration. It would take two
+strokes of the piston to cover one foot, or twelve inches,
+and as there are two strokes to a revolution it will be
+seen that this permits of a normal speed of 1,000 revolutions
+per minute for an engine with a six-inch stroke, if
+one does not exceed 1,000 feet per minute. If the stroke
+was only four inches, a normal speed of 1,500 revolutions
+per minute would be possible without exceeding the prescribed
+limit. The crank-shaft of a small engine, having
+three-inch stroke, could turn at a speed of 2,000 revolutions
+per minute without danger of exceeding the safe
+speed limit. It will be seen that the longer the stroke
+the slower the speed of the engine, if one desires to keep
+the piston speed within the bounds as recommended, but
+modern practice allows of greatly exceeding the speeds
+formerly thought best.</p>
+
+<h3><a name="SecVIII_7" id="SecVIII_7"></a>ADVANTAGES OF OFF-SET CYLINDERS</h3>
+
+<p>Another point upon which considerable difference of
+opinion exists relates to the method of placing the cylinder
+upon the crank-case&mdash;i.e., whether its center line
+should be placed directly over the center of the crank-shaft,
+or to one side of center. The motor shown at
+<a href="#Fig090">Fig. 90</a> is an off-set type, in that the center
+line of the<span class='pagenum'><a name="Page_242" id="Page_242">[242]</a></span>
+cylinder is a little to one side of the center of the crank-shaft.
+Diagrams are presented at <a href="#Fig091">Fig. 91</a> which show
+the advantages of off-set crank-shaft construction. The
+view at A is a section through a simple motor with the
+conventional cylinder placing, the center line of both
+crank-shaft and cylinder coinciding. The view at B shows<span class='pagenum'><a name="Page_243" id="Page_243">[243]</a></span>
+the cylinder placed to one side of center so that its center
+line is distinct from that of the crank-shaft and at some
+distance from it. The amount of off-set allowed is a point
+of contention, the usual amount being from fifteen to
+twenty-five per cent. of the stroke. The advantages of
+the off-set are shown at <a href="#Fig091">Fig. 91</a>, C. If the crank turns
+in direction of the arrow there is a certain resistance to
+motion which is proportional to the amount of energy
+exerted by the engine and the resistance offered by the
+load. There are two thrusts acting against the cylinder
+wall to be considered, that due to explosion or expansion
+of the gas, and that which resists the motion of the piston.
+These thrusts may be represented by arrows, one which
+acts directly in a vertical direction on the piston top, the<span class='pagenum'><a name="Page_244" id="Page_244">[244]</a></span>
+other along a straight line through the center of the
+connecting rod. Between these two thrusts one can draw
+a line representing a resultant force which serves to bring
+the piston in forcible contact with one side of the cylinder
+wall, this being known as side thrust. As shown at C,
+the crank-shaft is at 90 degrees, or about one-half stroke,
+and the connecting rod is at 20 degrees angle. The
+shorter connecting rod would increase the diagonal resultant
+and side thrusts, while a longer one would reduce
+the angle of the connecting rod and the side thrust of
+the piston would be less. With the off-set construction,
+as shown at D, it will be noticed that with the same connecting-rod
+length as shown at C and with the crank-shaft
+at 90 degrees of the circle that the connecting-rod
+angle is 14 degrees and the side thrust is reduced proportionately.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig090" id="Fig090"></a>
+<img src="images/illo237.png" alt="Fig. 90" width="450" height="557" />
+<p class="caption">Fig. 90.&mdash;Cross Section of Austro-Daimler Engine, Showing Offset Cylinder
+Construction. Note Applied Water Jacket and Peculiar Valve Action.</p></div>
+
+<p>Another important advantage is that greater efficiency
+is obtained from the explosion with an off-set crank-shaft,
+because the crank is already inclined when the piston is
+at top center, and all the energy imparted to the piston
+by the burning mixture can be exerted directly into producing
+a useful turning effort. When a cylinder is placed
+directly on a line with the crank-shaft, as shown at A,
+it will be evident that some of the force produced by the
+expansion of the gas will be exerted in a direct line and
+until the crank moves the crank throw and connecting
+rod are practically a solid member. The pressure which
+might be employed in obtaining useful turning effort is
+wasted by causing a direct pressure upon the lower half
+of the main bearing and the upper half of the crank-pin
+bushing.</p>
+
+<div class="figcenter" style="width: 550px;"><a name="Fig091" id="Fig091"></a>
+<img src="images/illo238.png" alt="Fig. 91" width="550" height="513" />
+<p class="caption">Fig. 91.&mdash;Diagrams Demonstrating Advantages of Offset Crank-Shaft
+Construction.</p></div>
+
+<p>Very good and easily understood illustrations showing
+advantages of the off-set construction are shown at
+E and F. This is a bicycle crank-hanger. It is advanced
+that the effort of the rider is not as well applied when
+the crank is at position E as when it is at position F.
+Position E corresponds to the position of the parts when
+the cylinder is placed directly over the crank-shaft center.<span class='pagenum'><a name="Page_245" id="Page_245">[245]</a></span>
+Position F may be compared to the condition which is
+present when the off-set cylinder construction is used.</p>
+
+<h3><a name="SecVIII_8" id="SecVIII_8"></a>VALVE LOCATION OF VITAL IMPORT</h3>
+
+<p>It has often been said that a chain is no stronger than
+its weakest link, and this is as true of the explosive motor
+as it is of any other piece of mechanism. Many motors
+which appeared to be excellently designed and which
+were well constructed did not prove satisfactory because
+some minor detail or part had not been properly considered
+by the designer. A factor having material bearing
+upon the efficiency of the internal combustion motor is
+the location of the valves and the shape of the combustion
+chamber which is largely influenced by their placing.
+The fundamental consideration of valve design is that
+the gases be admitted and discharged from the cylinder
+as quickly as possible in order that the speed of gas flow
+will not be impeded and produce back pressure. This is
+imperative in obtaining satisfactory operation in any
+form of motor. If the inlet passages are constricted the
+cylinder will not fill with explosive mixture promptly,
+whereas if the exhaust gases are not fully expelled the
+parts of the inert products of combustion retained dilute
+the fresh charge, making it slow burning and causing lost
+power and overheating. When an engine employs water
+as a cooling medium this substance will absorb the surplus
+heat readily, and the effects of overheating are not
+noticed as quickly as when air-cooled cylinders are employed.
+Valve sizes have a decided bearing upon the
+speed of motors and some valve locations permit the
+use of larger members than do other positions.</p>
+
+<p>While piston velocity is an important factor in determinations
+of power output, it must be considered from
+the aspect of the wear produced upon the various parts
+of the motor. It is evident that engines which run very
+fast, especially of high power, must be under a greater
+strain than those operating at lower speeds. The valve-operating
+mechanism is especially susceptible to the influence<span class='pagenum'><a name="Page_246" id="Page_246">[246]</a></span>
+of rapid movement, and the slower the engine the
+longer the parts will wear and the more reliable the
+valve action.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig092" id="Fig092"></a>
+<img src="images/illo241.png" alt="Fig. 92" width="450" height="520" />
+<p class="caption">Fig. 92.&mdash;Diagram Showing Forms of Cylinder Demanded by Different Valve
+Placings. A&mdash;T Head Type, Valves on Opposite Sides. B&mdash;L Head
+Cylinder, Valves Side by Side. C&mdash;L Head Cylinder, One Valve in Head,
+Other in Pocket. D&mdash;Inlet Valve Over Exhaust Member, Both in Side
+Pocket. E&mdash;Valve-in-the-Head Type with Vertical Valves. F&mdash;Inclined
+Valves Placed to Open Directly into Combustion Chamber.</p></div>
+
+<p>As will be seen by reference to the accompanying illustration,
+<a href="#Fig092">Fig. 92</a>, there are many ways in which valves may
+be placed in the cylinder. Each method outlined possesses
+some point of advantage, because all of the types<span class='pagenum'><a name="Page_247" id="Page_247">[247]</a></span>
+illustrated are used by reputable automobile manufacturers.
+The method outlined at <a href="#Fig092">Fig. 92</a>, A, is widely
+used, and because of its shape the cylinder is known as
+the &#8220;T&#8221; form. It is approved for automobile use for
+several reasons, the most important being that large
+valves can be employed and a well-balanced and symmetrical
+cylinder casting obtained. Two independent cam-shafts
+are needed, one operating the inlet valves, the
+other the exhaust members. The valve-operating mechanism
+can be very simple in form, consisting of a plunger
+actuated by the cam which transmits the cam motion to
+the valve-stem, raising the valve as the cam follower
+rides on the point of the cam. Piping may be placed
+without crowding, and larger manifolds can be fitted than
+in some other constructions. This has special value, as
+it permits the use of an adequate discharge pipe on the
+exhaust side with its obvious advantages. This method
+of cylinder construction is never found on airplane engines
+because it does not permit of maximum power
+output.</p>
+
+<p><a name="SecVIII_9" id="SecVIII_9"></a>On the other hand, if considered from a viewpoint of
+actual heat efficiency, it is theoretically the worst form of
+combustion chamber. This disadvantage is probably compensated
+for by uniformity of expansion of the cylinder
+because of balanced design. The ignition spark-plug may
+be located directly over the inlet valve in the path of the
+incoming fresh gases, and both valves may be easily removed
+and inspected by unscrewing the valve caps without
+taking off the manifolds.</p>
+
+<p>The valve installation shown at C is somewhat unusual,
+though it provides for the use of valves of large
+diameter. Easy charging is insured because of the large
+inlet valve directly in the top of the cylinder. Conditions
+may be reversed if necessary, and the gases discharged
+through this large valve. Both methods are used, though
+it would seem that the free exhaust provided by allowing
+the gases to escape directly from the combustion chamber
+through the overhead valve to the exhaust manifold<span class='pagenum'><a name="Page_248" id="Page_248">[248]</a></span>
+would make for more power. The method outlined at
+<a href="#Fig092">Fig. 92</a>, F and at <a href="#Fig090">Fig. 90</a> is one that has been widely
+employed on large automobile racing motors where extreme
+power is required, as well as in engines constructed
+for aviation service. The inclination of the valves permits
+the use of large valves, and these open directly into
+the combustion chamber. There are no pockets to retain
+heat or dead gas, and free intake and outlet of gas is
+obtained. This form is quite satisfactory from a theoretical
+point of view because of the almost ideal combustion
+chamber form. Some difficulty is experienced, however,
+in properly water-jacketing the valve chamber which
+experience has shown to be necessary if the engine is to
+have high power.</p>
+
+<p>The motor shown at <a href="#Fig092">Fig. 92</a>, B and <a href="#Fig088">Fig. 88</a> employs
+cylinders of the &#8220;L&#8221; type. Both valves are placed in
+a common extension from the combustion chamber, and
+being located side by side both are actuated from a common
+cam-shaft. The inlet and exhaust pipes may be
+placed on the same side of the engine and a very compact
+assemblage is obtained, though this is optional if
+passages are cored in the cylinder pairs to lead the gases
+to opposite sides. The valves may be easily removed
+if desired, and the construction is fairly good from the
+viewpoint of both foundry man and machinist. The chief
+disadvantage is the limited area of the valves and the
+loss of heat efficiency due to the pocket. This form of
+combustion chamber, however, is more efficient than the
+&#8220;T&#8221; head construction, though with the latter the use of
+larger valves probably compensates for the greater heat
+loss. It has been stated as an advantage of this construction
+that both manifolds can be placed at the same
+side of the engine and a compact assembly secured. On
+the other hand, the disadvantage may be cited that in
+order to put both pipes on the same side they must be
+of smaller size than can be used when the valves are
+oppositely placed. The &#8220;L&#8221; form cylinder is sometimes
+made more efficient if but one valve is placed in the pocket<span class='pagenum'><a name="Page_249" id="Page_249">[249]</a></span>
+while the other is placed over it. This construction is
+well shown at <a href="#Fig092">Fig. 92</a>, D and is found on Anzani motors.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig093" id="Fig093"></a>
+<img src="images/illo244.png" alt="Fig. 93" width="450" height="433" />
+<p class="caption">Fig. 93.&mdash;Sectional View of Engine Cylinder Showing Valve and Cage
+Installation.</p></div>
+
+<p>The method of valve application shown at <a href="#Fig087">Fig. 87</a> is
+an ingenious method of overcoming some of the disadvantages
+inherent with valve-in-the-head motors. In the
+first place it is possible to water-jacket the valves thoroughly,
+which is difficult to accomplish when they are
+mounted in cages. The water circulates directly around
+the walls of the valve chambers, which is superior to a
+construction where separate cages are used, as there are
+two thicknesses of metal with the latter, that of the valve-cage
+proper and the wall of the cylinder. The cooling
+medium is in contact only with the outer wall, and as
+there is always a loss of heat conductivity at a joint it<span class='pagenum'><a name="Page_250" id="Page_250">[250]</a></span>
+is practically impossible to keep the exhaust valves and
+their seats at a uniform temperature. The valves may
+be of larger size without the use of pockets when seating
+directly in the head. In fact, they could be equal in
+diameter to almost half the bore of the cylinder, which
+provides an ideal condition of charge placement and exhaust.
+When valve grinding is necessary the entire head
+is easily removed by taking off six nuts and loosening
+inlet manifold connections, which operation would
+be necessary even if cages were employed, as in the
+engine shown at <a href="#Fig093">Fig. 93</a>.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig094" id="Fig094"></a>
+<img src="images/illo245.png" alt="Fig. 94" width="450" height="466" />
+<p class="caption">Fig. 94.&mdash;Diagrams Showing How Gas Enters Cylinder Through Overhead
+Valves and Other Types. A&mdash;Tee Head Cylinder. B&mdash;L Head Cylinder.
+C&mdash;Overhead Valve.</p></div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig095" id="Fig095"></a>
+<img src="images/illo246.png" alt="Fig. 95" width="400" height="499" />
+<p class="caption">Fig. 95.&mdash;Conventional Methods of Operating Internal Combustion Motor
+Valves.</p></div>
+
+<p><span class='pagenum'><a name="Page_251" id="Page_251">[251]</a></span>At
+<a href="#Fig094">Fig. 94</a>, A and B, a section through a typical &#8220;L&#8221;-shaped
+cylinder is depicted. It will be evident that where
+a pocket construction is employed, in addition to its faculty
+for absorbing heat, the passage of gas would be
+impeded. For example, the inlet gas rushing in through
+the open valve would impinge sharply upon the valve-cap
+or combustion head directly over the valve and then must
+turn at a sharp angle to enter the combustion chamber<span class='pagenum'><a name="Page_252" id="Page_252">[252]</a></span>
+and then at another sharp angle to fill the cylinders. The
+same conditions apply to the exhaust gases, though they
+are reversed. When the valve-in-the-head type of cylinder
+is employed, as at C, the only resistance offered the
+gas is in the manifold. As far as the passage of the
+gases in and out of the cylinder is concerned, ideal conditions
+obtain. It is claimed that valve-in-the-head motors
+are more flexible and responsive than other forms, but the
+construction has the disadvantage in that the valves must
+be opened through a rather complicated system of push
+rods and rocker arms instead of the simpler and direct
+plunger which can be used with either the &#8220;T&#8221; or &#8220;L&#8221;
+head cylinders. This is clearly outlined in the illustrations
+at <a href="#Fig095">Fig. 95</a>, where A shows the valve in the head-operating
+mechanism necessary if the cam-shaft is carried
+at the cylinder base, while B shows the most direct
+push-rod action obtained with &#8220;T&#8221; or &#8220;L&#8221; head cylinder
+placing.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig096" id="Fig096"></a>
+<img src="images/illo247.png" alt="Fig. 96" width="600" height="283" />
+<p class="caption">Fig. 96.&mdash;Examples of Direct Valve Actuation by Overhead Cam-Shaft.
+A&mdash;Mercedes. B&mdash;Hall-Scott. C&mdash;Wisconsin.</p></div>
+
+<p class="center" style="margin-top: 2em;"><span class='pagenum'><a name="Page_253" id="Page_253">[253]</a></span>
+<a name="Fig097" id="Fig097"></a>Fig. 97.</p>
+
+<p class="center fsize200 gesp" style="margin-bottom: 2em;">CENSORED</p>
+
+<p class="center" style="margin-top: 2em;"><a name="Fig098" id="Fig098"></a>Fig. 98.</p>
+
+<p class="center fsize200 gesp">CENSORED</p>
+
+<p>The objection can be easily met by carrying the cam-shaft
+above the cylinders and driving it by means of
+gearing. The types of engine cylinders using this construction
+are shown at <a href="#Fig096">Fig. 96</a>, and it will be evident that
+a positive and direct valve action is possible by following
+the construction originated by the Mercedes (German)<span class='pagenum'><a name="Page_254" id="Page_254">[254]</a></span>
+aviation engine designers and outlined at A. The other
+forms at B and C are very clearly adaptations of this
+design. The Hall-Scott engine at <a href="#Fig097">Fig. 97</a> is depicted in
+part section and no trouble will be experienced in understanding
+the bevel pinion and gear drive from the crank-shaft<span class='pagenum'><a name="Page_255" id="Page_255">[255]</a></span>
+to the overhead cam-shaft through a vertical counter-shaft.
+A very direct valve action is used in the
+Duesenberg engines, one of which is shown in part section
+at <a href="#Fig098">Fig. 98</a>. The valves are parallel with the piston top
+and are actuated by rocker arms, one end of which bears
+against the valve stem, and the other rides the cam-shaft.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig099" id="Fig099"></a>
+<img src="images/illo250.png" alt="Fig. 99" width="500" height="411" />
+<p class="caption">Fig. 99.&mdash;Sectional Views Showing Arrangement of Novel Concentric Valve
+Arrangement Devised by Panhard for Aerial Engines.</p></div>
+
+<p>The form shown at <a href="#Fig099">Fig. 99</a> shows an ingenious application
+of the valve-in-the-head idea which permits one
+to obtain large valves. It has been used on some of the
+Panhard aviation engines and on the American Aeromarine
+power plants. The inlet passage is controlled
+by the sliding sleeve which is hollow and slotted so as
+to permit the inlet gases to enter the cylinder through
+the regular type poppet valve which seats in the exhaust
+sleeve. When the exhaust valve is operated by the tappet
+rod and rocker arm the intake valve is also carried<span class='pagenum'><a name="Page_256" id="Page_256">[256]</a></span>
+down with it. The intake gas passage is closed, however,
+and the burned gases are discharged through the large
+annular passage surrounding the sleeve. When the inlet
+valve leaves its seat in the sleeve the passage of cool
+gas around the sleeve keeps the temperature of both
+valves to a low point and the danger of warping is minimized.
+A dome-shaped combustion chamber may be used,
+which is an ideal form in conserving heat efficiency, and
+as large valves may be installed the flow of both fresh
+and exhaust gases may be obtained with minimum resistance.
+The intake valve is opened by a small auxiliary
+rocker arm which is lifted when the cam follower rides
+into the depression in the cam by the action of the strong
+spring around the push rod. When the cam follower rides
+on the high point the exhaust sleeve is depressed from
+its seat against the cylinder. By using a cam having both
+positive and negative profiles, a single rod suffices for
+both valves because of its push and pull action.</p>
+
+<h3><a name="SecVIII_10" id="SecVIII_10"></a>VALVE DESIGN AND CONSTRUCTION</h3>
+
+<p>Valve dimensions are an important detail to be considered
+and can be determined by several conditions,
+among which may be cited method of installation, operating
+mechanism, material employed, engine speed desired,
+manner of cylinder cooling and degree of lift
+desired. A review of various methods of valve location
+has shown that when the valves are placed directly in
+the head we can obtain the ideal cylinder form, though
+larger valves may be used if housed in a separate pocket,
+as afforded by the &#8220;T&#8221; head construction. The method
+of operation has much to do with the size of the valves.
+For example, if an automatic inlet valve is employed it
+is good practice to limit the lift and obtain the required
+area of port opening by augmenting the diameter. Because
+of this a valve of the automatic type is usually
+made twenty per cent. larger than one mechanically operated.
+When both are actuated by cam mechanism, as is
+now common practice, they are usually made the same<span class='pagenum'><a name="Page_257" id="Page_257">[257]</a></span>
+size and are interchangeable, which greatly simplifies
+manufacture. The relation of valve diameter to cylinder
+bore is one that has been discussed for some time
+by engineers. The writer&#8217;s experience would indicate that
+they should be at least half the bore, if possible. While
+the mushroom type or poppet valve has become standard
+and is the most widely used form at the present time,
+there is some difference of opinion among designers as
+to the materials employed and the angle of the seat. Most
+valves have a bevel seat, though some have a flat seating.
+The flat seat valve has the distinctive advantage of providing
+a clear opening with lesser lift, this conducing to
+free gas flow. It also has value because it is silent in
+operation, but the disadvantage is present that best material
+and workmanship must be used in their construction
+to obtain satisfactory results. As it can be made very
+light it is particularly well adapted for use as an automatic
+inlet valve. Among other disadvantages cited is
+the claim that it is more susceptible to derangement, owing
+to the particles of foreign matter getting under the seat.
+With a bevel seat it is argued that the foreign matter
+would be more easily dislodged by the gas flow, and that
+the valve would close tighter because it is drawn positively
+against the bevel seat.</p>
+
+<p>Several methods of valve construction are the vogue,
+the most popular form being the one-piece type; those
+which are composed of a head of one material and stem
+of another are seldom used in airplane engines because
+they are not reliable. In the built-up construction the
+head is usually of high nickel steel or cast iron, which
+metals possess good heat-resisting qualities. Heads made
+of these materials are not likely to warp, scale, or pit,
+as is sometimes the case when ordinary grades of machinery
+steel are used. The cast-iron head construction
+is not popular because it is often difficult to keep the head
+tight on the stem. There is a slight difference in expansion
+ratio between the head and the stem, and as the
+stem is either screwed or riveted to the cast-iron head<span class='pagenum'><a name="Page_258" id="Page_258">[258]</a></span>
+the constant hammering of the valve against its seat may
+loosen the joint. As soon as the head is loose on the stem
+the action of the valve becomes erratic. The best practice
+is to machine the valves from tungsten steel forgings.
+This material has splendid heat-resisting qualities and
+will not pit or become scored easily. Even the electrically
+welded head to stem types which are used in automobile
+engines are not looked upon with favor in the
+aviation engine. Valve stem guides and valve stems must
+be machined very accurately to insure correct action. The
+usual practice in automobile engines is shown at <a href="#Fig100">Fig. 100</a>.</p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig100" id="Fig100"></a>
+<img src="images/illo253.png" alt="Fig. 100" width="350" height="398" />
+<p class="caption">Fig. 100.&mdash;Showing Clearance Allowed Between Valve Stem
+and Valve Stem Guide to Secure Free Action.</p></div>
+
+<h3><a name="SecVIII_11" id="SecVIII_11"></a>VALVE OPERATION</h3>
+
+<p>The methods of valve operation commonly used vary
+according to the type of cylinder construction employed.
+In all cases the valves are lifted from their seats by cam-actuated
+mechanism. Various forms of valve-lifting cams
+are shown at <a href="#Fig101">Fig. 101</a>. As will be seen,
+a cam consists<span class='pagenum'><a name="Page_259" id="Page_259">[259]</a></span>
+of a circle to which a raised, approximately triangular
+member has been added at one point. When the cam
+follower rides on the circle, as shown at <a href="#Fig102">Fig. 102</a>, there
+is no difference in height between the cam center and its
+periphery and there is no movement of the plunger. As
+soon as the raised portion of the cam strikes the plunger
+it will lift it, and this reciprocating movement is transmitted
+to the valve stem by suitable mechanical connections.</p>
+
+<div class="figcenter" style="width: 550px;"><a name="Fig101" id="Fig101"></a>
+<img src="images/illo254.png" alt="Fig. 101" width="550" height="187" />
+<p class="caption">Fig. 101.&mdash;Forms of Valve-Lifting Cams Generally Employed. A&mdash;Cam
+Profile for Long Dwell and Quick Lift. B&mdash;Typical Inlet Cam Used
+with Mushroom Type Follower. C&mdash;Average Form of Cam. D&mdash;Designed
+to Give Quick Lift and Gradual Closing.</p></div>
+
+<p>The cam forms outlined at <a href="#Fig101">Fig. 101</a> are those commonly
+used. That at A is used on engines where it is
+desired to obtain a quick lift and to keep the valve fully
+opened as long as possible. It is a noisy form, however,
+and is not very widely employed. That at B is utilized
+more often as an inlet cam while the profile shown at C
+is generally depended on to operate exhaust valves. The
+cam shown at D is a composite form which has some
+of the features of the other three types. It will give the
+quick opening of form A, the gradual closing of form B,
+and the time of maximum valve opening provided by cam
+profile C.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig102" id="Fig102"></a>
+<img src="images/illo255.png" alt="Fig. 102" width="500" height="316" />
+<p class="caption">Fig. 102.&mdash;Showing Principal Types of Cam Followers which Have Received
+General Application.</p></div>
+
+<p>The various types of valve plungers used are shown
+at <a href="#Fig102">Fig. 102</a>. That shown at A is the simplest form, consisting
+of a simple cylindrical member having a rounded
+end which follows the cam profile. These are sometimes<span class='pagenum'><a name="Page_260" id="Page_260">[260]</a></span>
+made of square stock or kept from rotating by means of
+a key or pin. A line contact is possible when the plunger
+is kept from turning, whereas but a single point bearing
+is obtained when the plunger is cylindrical and free to
+revolve. The plunger shown at A will follow only cam
+profiles which have gradual lifts. The plunger shown at
+B is left free to revolve in the guide bushing and is provided
+with a flat mushroom head which serves as a cam
+follower. The type shown at C carries a roller at its
+lower end and may follow very irregular cam profiles if
+abrupt lifts are desired. While forms A and B are the
+simplest, that outlined at C in its various forms is more
+widely used. Compound plungers are used on the Curtiss
+OX-2 motors, one inside the other. The small or inner one
+works on a cam of conventional design, the outer plunger
+follows a profile having a flat spot to permit of a pull
+rod action instead of a push rod action. All the methods
+in which levers are used to operate valves are more or
+less noisy because clearance must be left between the valve
+stem and the stop of the plunger. The space must be
+taken up before the valve will leave its seat, and when<span class='pagenum'><a name="Page_261" id="Page_261">[261]</a></span>
+the engine is operated at high speeds the forcible contact
+between the plunger and valve stem produces a rattling
+sound until the valves become heated and expand and the
+stems lengthen out. Clearance must be left between the
+valve stems and actuating means. This clearance is clearly
+shown in <a href="#Fig103">Fig. 103</a> and should be <span class="nowrap">.020&#8242;&#8242;</span> (twenty thousandths)
+when engine is cold. The amount of clearance
+allowed depends entirely upon the design of the engine
+and length of valve stem. On the Curtiss OX-2 engines
+the clearance is but <span class="nowrap">.010&#8242;&#8242;</span> (ten thousandths) because the
+valve stems are shorter. Too little clearance will result
+in loss of power or misfiring when engine is hot. Too
+much clearance will not allow the valve to open its full
+amount and will disturb the timing.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig103" id="Fig103"></a>
+<img src="images/illo256.png" alt="Fig. 103" width="500" height="310" />
+<p class="caption">Fig. 103.&mdash;Diagram Showing Proper Clearance to Allow Between Adjusting
+Screw and Valve Stems in Hall-Scott Aviation Engines.</p></div>
+
+<h3><a name="SecVIII_12" id="SecVIII_12"></a>METHODS OF DRIVING CAM-SHAFT</h3>
+
+<p>Two systems of cam-shaft operation are used. The
+most common of these is by means of gearing of some
+form. If the cam-shaft is at right angles to the crank-shaft
+it may be driven by worm, spiral, or bevel gearing.<span class='pagenum'><a name="Page_262" id="Page_262">[262]</a></span>
+If the cam-shaft is parallel to the crank-shaft, simple spur
+gear or chain connection may be used to turn it. A typical
+cam-shaft for an eight-cylinder V engine is shown at
+<a href="#Fig104">Fig. 104</a>. It will be seen that the sixteen cams are forged
+integrally with the shaft and that it is spur-gear driven.
+The cam-shaft drive of the Hall-Scott motor is shown at
+<a href="#Fig097">Fig. 97</a>.</p>
+
+<div class="figcenter" style="width: 550px;"><a name="Fig104" id="Fig104"></a>
+<img src="images/illo257.jpg" alt="Fig. 104" width="550" height="201" />
+<p class="caption">Fig. 104.&mdash;Cam-Shaft of Thomas Airplane Motor Has Cams Forged Integral.
+Note Split Cam-Shaft Bearings and Method of Gear Retention.</p></div>
+
+<p>While gearing is more commonly used, considerable
+attention has been directed of late to silent chains for
+cam-shaft operation. The ordinary forms of block or
+roller chain have not proven successful in this application,
+but the silent chain, which is in reality a link belt
+operating over toothed pulleys, has demonstrated its
+worth. The tendency to its use is more noted on foreign
+motors than those of American design. It first came to
+public notice when employed on the Daimler-Knight engine
+for driving the small auxiliary crank-shafts which
+reciprocated the sleeve valves. The advantages cited for
+the application of chains are, first, silent operation, which
+obtains even after the chains have worn considerably;
+second, in designing it is not necessary to figure on maintaining
+certain absolute center distances between the
+crank-shaft and cam-shaft sprockets, as would be the case
+if conventional forms of gearing were used. On some
+forms of motor employing gears, three and even four<span class='pagenum'><a name="Page_263" id="Page_263">[263]</a></span>
+members are needed to turn the cam-shaft. With a chain
+drive but two sprockets are necessary, the chain forming
+a flexible connection which permits the driving and driven
+members to be placed at any distance apart that the
+exigencies of the design demand. When chains are used
+it is advised that some means for compensating chain
+slack be provided, or the valve timing will lag when
+chains are worn. Many combination drives may be
+worked out with chains that would not be possible with
+other forms of gearing. Direct gear drive is favored at
+the present time by airplane engine designers because they
+are the most certain and positive means, even when a
+number of gears must be used as intermediate drive
+members. With overhead cam-shafts, bevel gears work
+out very well in practice, as in the Hall-Scott motors and
+others of that type.</p>
+
+<h3><a name="SecVIII_13" id="SecVIII_13"></a>VALVE SPRINGS</h3>
+
+<p>Another consideration of importance is the use of
+proper valve-springs, and particular care should be taken
+with those, of automatic valves. The spring must be weak
+enough to allow the valve to open when the suction is
+light, and must be of sufficient strength to close it in
+time at high speeds. It should be made as large as possible
+in diameter and with a large number of convolutions,
+in order that fatigue of the metal be obviated, and it is
+imperative that all springs be of the same strength when
+used on a multiple-cylinder engine. Practically all valves
+used to control the gas flow in airplane engines are mechanically
+operated. On the exhaust valve the spring
+must be strong enough so that the valve will not be sucked
+in on the inlet stroke. It should be borne in mind that
+if the spring is too strong a strain will be imposed on
+the valve-operating mechanism, and a hammering action
+produced which may cause deformation of the valve-seat.
+Only pressure enough to insure that the operating mechanism
+will follow the cam is required. It is common
+practice to make the inlet and exhaust valve springs of<span class='pagenum'><a name="Page_264" id="Page_264">[264]</a></span>
+the same tension when the valves are of the same size
+and both mechanically operated. This is done merely to
+simplify manufacture and not because it is necessary for
+the inlet valve-spring to be as strong as the other. Valve
+springs of the helical coil type are generally used, though
+torsion or &#8220;scissors&#8221; springs and laminated or single-leaf
+springs are also utilized in special applications. Two<span class='pagenum'><a name="Page_265" id="Page_265">[265]</a></span>
+springs are used on each valve in some valve-in-the-head
+types; a spring of small pitch diameter inside the regular
+valve-spring and concentric with it. Its function is to
+keep the valve from falling into the cylinder in event of
+breakage of the main spring in some cases, and to provide
+a stronger return action in others.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig105" id="Fig105"></a>
+<img src="images/illo259.png" alt="Fig. 105" width="450" height="548" />
+<p class="caption">Fig. 105.&mdash;Section Through Cylinder of Knight Motor, Showing Important
+Parts of Valve Motion.</p></div>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig106" id="Fig106"></a>
+<img src="images/illo260.png" alt="Fig. 106" width="450" height="587" />
+<p class="caption">Fig. 106.&mdash;Diagrams Showing Knight Sleeve Valve Action.</p></div>
+
+<p class='pagenum'><a name="Page_266" id="Page_266">[266]</a></p>
+
+<h3>KNIGHT SLIDE VALVE MOTOR</h3>
+
+<p>The sectional view through the cylinder at <a href="#Fig105">Fig. 105</a>
+shows the Knight sliding sleeves and their actuating
+means very clearly. The diagrams at <a href="#Fig106">Fig. 106</a> show
+graphically the sleeve movements and their relation to
+the crank-shaft and piston travel. The action may be
+summed up as follows: The inlet port begins to open
+when the lower edge of the opening of the outside sleeve
+which is moving down passes the top of the slot in the
+inner member also moving downwardly. The inlet port
+is closed when the lower edge of the slot in the inner
+sleeve which is moving up passes the top edge of the port
+in the outer sleeve which is also moving toward the top
+of the cylinder. The inlet opening extends over two hundred
+degrees of crank motion. The exhaust port is uncovered
+slightly when the lower edge of the port in the
+inner sleeve which is moving down passes the lower edge
+of the portion of the cylinder head which protrudes in
+the cylinder. When the top of the port in the outer sleeve
+traveling toward the bottom of the cylinder passes the
+lower edge of the slot in the cylinder wall the exhaust
+passage is closed. The exhaust opening extends over a
+period corresponding to about two hundred and forty
+degrees of crank motion. The Knight motor has not been
+applied to aircraft to the writer&#8217;s knowledge, but an
+eight-cylinder Vee design that might be useful in that
+connection if lightened is shown at <a href="#Fig107">Fig. 107</a>. The main
+object is to show that the Knight valve action is the only
+other besides the mushroom or poppet valve that has been
+applied successfully to high speed gasoline engines.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig107" id="Fig107"></a>
+<img src="images/illo262.png" alt="Fig. 107" width="500" height="526" />
+<p class="caption">Fig. 107.&mdash;Cross Sectional View of Knight Type Eight Cylinder V Engine.</p></div>
+
+<h3><a name="SecVIII_14" id="SecVIII_14"></a>VALVE TIMING</h3>
+
+<p>It is in valve timing that the greatest difference of
+opinion prevails among engineers, and it is rare that one
+will see the same formula in different motors. It is true
+that the same timing could not be used with motors of<span class='pagenum'><a name="Page_267" id="Page_267">[267]</a></span>
+different construction, as there are many factors which
+determine the amount of lead to be given to the valves.
+The most important of these is the relative size of the
+valve to the cylinder bore, the speed of rotation it is
+desired to obtain, the fuel efficiency, the location of the
+valves, and other factors too numerous to mention.</p>
+
+<p>Most of the readers should be familiar with the cycle
+of operation of the internal combustion motor of the
+four-stroke type, and it seems unnecessary to go into
+detail except to present a review. The first stroke of the
+piston is one in which a charge of gas is taken into the<span class='pagenum'><a name="Page_268" id="Page_268">[268]</a></span>
+motor; the second stroke, which is in reverse direction
+to the first, is a compression stroke, at the end of which
+the spark takes place, exploding the charge and driving
+the piston down on the third or expansion stroke, which
+is in the same direction as the intake stroke, and finally,
+after the piston has nearly reached the end of this stroke,
+another valve opens to allow the burned gases to escape,
+and remains open until the piston has reached the end
+of the fourth stroke and is in a position to begin the
+series over again. The ends of the strokes are reached
+when the piston comes to a stop at either top or bottom
+of the cylinder and reverses its motion. That point is
+known as a center, and there are two for each cylinder,
+top and bottom centers, respectively.</p>
+
+<p>All circles may be divided into 360 parts, each of
+which is known as a degree, and, in turn, each of these
+degrees may be again divided into minutes and seconds,
+though we need not concern ourselves with anything less
+than the degree. Each stroke of the piston represents
+180 degrees travel of the crank, because two strokes represent
+one complete revolution of three hundred and sixty
+degrees. The top and bottom centers are therefore separated
+by 180 degrees. Theoretically each phase of a
+four-cycle engine begins and ends at a center, though in
+actual practice the inertia or movement of the gases
+makes it necessary to allow a lead or lag to the valve, as
+the case may be. If a valve opens before a center, the
+distance is called &#8220;lead&#8221;; if it closes after a center, this
+distance is known as &#8220;lag.&#8221; The profile of the cams
+ordinarily used to open or close the valves represents a
+considerable time in relation to the 180 degrees of the
+crank-shaft travel, and the area of the passages through
+which the gases are admitted or exhausted is quite small
+owing to the necessity of having to open or close the
+valves at stated times; therefore, to open an adequately
+large passage for the gases it is necessary to open the
+valves earlier and close them later than at centers.</p>
+
+<p>That advancing the opening of the exhaust valve was<span class='pagenum'><a name="Page_269" id="Page_269">[269]</a></span>
+of value was discovered on the early motors and is explained
+by the necessity of releasing a large amount of
+gas, the volume of which has been greatly raised by the
+heat of combustion. When the inlet valves were mechanically
+operated it was found that allowing them to lag
+at closing enabled the inspiration of a greater volume of
+gas. Disregarding the inertia or flow of the gases, opening
+the exhaust at center would enable one to obtain full
+value of the expanding gases the entire length of the
+piston stroke, and it would not be necessary to keep the
+valve open after the top center, as the reverse stroke
+would produce a suction effect which might draw some
+of the inert charge back into the cylinder. On the other
+hand, giving full consideration to the inertia of the gas,
+opening the valve before center is reached will provide
+for quick expulsion of the gases, which have sufficient
+velocity at the end of the stroke, so that if the valve is
+allowed to remain open a little longer, the amount of lag
+varying with the opinions of the designer, the cylinder
+is cleared in a more thorough manner.</p>
+
+<h3><a name="SecVIII_15" id="SecVIII_15"></a>BLOWING BACK</h3>
+
+<p>When the factor of retarded opening is considered
+without reckoning the inertia of the gases, it would
+appear that if the valve were allowed to remain open
+after center had passed, say, on the closing of the inlet,
+the piston, having reversed its motion, would have the
+effect of expelling part of the fresh charge through the
+still open valve as it passed inward at its compression
+stroke. This effect is called blowing back, and is often
+noted with motors where the valve settings are not absolutely
+correct, or where the valve-springs or seats are
+defective and prevent proper closing.</p>
+
+<p>This factor is not of as much import as might appear,
+as on closer consideration it will be seen that the movement
+of the piston as the crank reaches either end of the
+stroke is less per degree of angular movement than it
+is when the angle of the connecting rod is greater. Then,<span class='pagenum'><a name="Page_270" id="Page_270">[270]</a></span>
+again, a certain length of time is required for the reversal
+of motion of the piston, during which time the crank is
+in motion but the piston practically at a standstill. If the
+valves are allowed to remain open during this period,
+the passage of the gas in or out of the cylinder will be
+by its own momentum.</p>
+
+<h3><a name="SecVIII_16" id="SecVIII_16"></a>LEAD GIVEN EXHAUST VALVE</h3>
+
+<p>The faster a motor turns, all other things being equal,
+the greater the amount of lead or advance it is necessary
+to give the opening of the exhaust valve. It is self-evident
+truth that if the speed of a motor is doubled it
+travels twice as many degrees in the time necessary to
+lower the pressure. As most designers are cognizant of
+this fact, the valves are proportioned accordingly. It is
+well to consider in this respect that the cam profile has
+much to do with the manner in which the valve is opened;
+that is, the lift may be abrupt and the gas allowed to
+escape in a body, or the opening may be gradual, the
+gas issuing from the cylinder in thin streams. An analogy
+may be made with the opening of any bottle which contains
+liquid highly carbonated. If the cork is removed
+suddenly the gas escapes with a loud pop, but, on the
+other hand, if the bottle is uncorked gradually, the gas
+escapes from the receptacle in thin streams around the
+cork, and passage of the gases to the air is accomplished
+without noise. While the second plan is not harsh, it
+is slower than the former, as must be evident.</p>
+
+<h3><a name="SecVIII_17" id="SecVIII_17"></a>EXHAUST CLOSING, INLET OPENING</h3>
+
+<p>A point which has been much discussed by engineers
+is the proper relation of the closing of the exhaust valve
+and the opening of the inlet. Theoretically they should
+succeed each other, the exhaust closing at upper dead
+center and the inlet opening immediately afterward. The
+reason why a certain amount of lag is given the exhaust
+closing in practice is that the piston cannot drive the<span class='pagenum'><a name="Page_271" id="Page_271">[271]</a></span>
+gases out of the cylinder unless they are compressed to
+a degree in excess of that existing in the manifold or
+passages, and while toward the end of the stroke this
+pressure may be feeble, it is nevertheless indispensable.
+At the end of the piston&#8217;s stroke, as marked by the upper
+dead center, this compression still exists, no matter how
+little it may be, so that if the exhaust valve is closed and
+the inlet opened immediately afterward, the pressure
+which exists in the cylinder may retard the entrance of
+the fresh gas and a certain portion of the inert gas may
+penetrate into the manifold. As the piston immediately
+begins to aspirate, this may not be serious, but as these
+gases are drawn back into the cylinder the fresh charge
+will be diluted and weakened in value. If the spark-plug
+is in a pocket, the points may be surrounded by this weak
+gas, and the explosion will not be nearly as energetic as
+when the ignition spark takes place in pure mixture.</p>
+
+<p>It is a well-known fact that the exhaust valve should
+close after dead center and that a certain amount of lag
+should be given to opening of the inlet. The lag given
+the closing of the exhaust valve should not be as great
+as that given the closing of the inlet valve. Assuming
+that the excess pressure of the exhaust will equal the
+depression during aspiration, the time necessary to complete
+the emptying of the cylinder will be proportional
+to the volume of the gas within it. At the end of the
+suction stroke the volume of gas contained in the cylinder
+is equal to the cylindrical volume plus the space of the
+combustion chamber. At the end of the exhaust stroke
+the volume is but that of the dead space, and from one-third
+to one-fifth its volume before compression. While
+it is natural to assume that this excess of burned gas
+will escape faster than the fresh gas will enter the cylinder,
+it will be seen that if the inlet valve were allowed
+to lag twenty degrees, the exhaust valve lag need not be
+more than five degrees, providing that the capacity of
+the combustion chamber was such that the gases occupied
+one-quarter of their former volume.</p>
+
+<p><span class='pagenum'><a name="Page_272" id="Page_272">[272]</a></span>It is evident that no absolute rule can be given, as
+back pressure will vary with the design of the valve
+passages, the manifolds, and the construction of the
+muffler. The more direct the opening, the sooner the
+valve can be closed and the better the cylinder cleared.
+Ten degrees represent an appreciable angle of the crank,
+and the time required for the crank to cover this angular
+motion is not inconsiderable and an important quantity of
+the exhaust may escape, but the piston is very close to
+the dead center after the distance has been covered.</p>
+
+<p>Before the inlet valve opens there should be a certain
+depression in the cylinder, and considerable lag may be
+allowed before the depression is appreciable. So far as
+the volume of fresh gas introduced during the admission
+stroke is concerned, this is determined by the displacement
+of the piston between the point where the inlet valve
+opens and the point of closing, assuming that sufficient
+gas has been inspired so that an equilibrium of pressure
+has been established between the interior of the cylinder
+and the outer air. The point of inlet opening varies with
+different motors. It would appear that a fair amount of
+lag would be fifteen degrees past top center for the inlet
+opening, as a certain depression will exist in the cylinder,
+assuming that the exhaust valve has closed five or ten
+degrees after center, and at the same time the piston has
+not gone down far enough on its stroke to materially
+decrease the amount of gas which will be taken into the
+cylinder.</p>
+
+<h3><a name="SecVIII_18" id="SecVIII_18"></a>CLOSING THE INLET VALVE</h3>
+
+<p>As in the case with the other points of opening and
+closing, there is a wide diversity of practice as relates
+to closing the inlet valve. Some of the designers close
+this exactly at bottom center, but this practice cannot
+be commended, as there is a considerable portion of time,
+at least ten or fifteen degrees angular motion of the crank,
+before the piston will commence to travel to any extent
+on its compression stroke. The gases rushing into the<span class='pagenum'><a name="Page_273" id="Page_273">[273]</a></span>
+cylinder have considerable velocity, and unless an equilibrium
+is obtained between the pressure inside and that
+of the atmosphere outside, they will continue to rush into
+the cylinder even after the piston ceases to exert any
+suction effect.</p>
+
+<p>For this reason, if the valve is closed exactly on center,
+a full charge may not be inspired into the cylinder,
+though if the time of closing is delayed, this momentum
+or inertia of the gas will be enough to insure that a
+maximum charge is taken into the cylinder. The writer
+considers that nothing will be gained if the valve is allowed
+to remain open longer than twenty degrees, and an
+analysis of practice in this respect would seem to confirm
+this opinion. From that point in the crank movement
+the piston travel increases and the compressive effect is
+appreciable, and it would appear that a considerable proportion
+of the charge might be exhausted into the manifold
+and carburetor if the valve were allowed to remain
+open beyond a point corresponding to twenty degrees
+angular movement of the crank.</p>
+
+<h3><a name="SecVIII_19" id="SecVIII_19"></a>TIME OF IGNITION</h3>
+
+<p>In this country engineers unite in providing a variable
+time of ignition, though abroad some difference of
+opinion is noted on this point. The practice of advancing
+the time of ignition, when affected electrically, was
+severely condemned by early makers, these maintaining
+that it was necessary because of insufficient heat and
+volume of the spark, and it was thought that advancing
+ignition was injurious. The engineers of to-day appreciate
+the fact that the heat of the electric spark, especially
+when from a mechanical generator of electrical
+energy, is the only means by which we can obtain practically
+instantaneous explosion, as required by the operation
+of motors at high speeds, and for the combustion
+of large volumes of gas.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig108" id="Fig108"></a>
+<img src="images/illo269.png" alt="Fig. 108" width="450" height="571" />
+<p class="caption">Fig. 108.&mdash;Diagrams Explaining Valve and Ignition Timing of Hall-Scott
+Aviation Engine.</p></div>
+
+<p>It is apparent that a motor with a fixed point of<span class='pagenum'><a name="Page_274" id="Page_274">[274]</a></span>
+ignition is not as desirable, in every way, as one in which
+the ignition can be advanced to best meet different requirements,
+and the writer does not readily perceive any
+advantage outside of simplicity of control in establishing
+a fixed point of ignition. In fact, there seems to be some
+difference of opinion among those designers who favor<span class='pagenum'><a name="Page_275" id="Page_275">[275]</a></span>
+fixed ignition, and in one case this is located forty-three
+degrees ahead of center, and in another motor the point
+is fixed at twenty degrees, so that it may be said that
+this will vary as much as one hundred per cent. in various
+forms. This point will vary with different methods of
+ignition, as well as the location of the spark-plug or
+igniter. For the sake of simplicity, most airplane engines
+use set spark; if an advancing and retarding mechanism
+is fitted, it is only to facilitate starting, as the
+spark is kept advanced while in flight, and control is by
+throttle alone.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig109" id="Fig109"></a>
+<img src="images/illo270.png" alt="Fig. 109" width="400" height="396" />
+<p class="caption">Fig. 109.&mdash;Timing Diagram of Typical Six-Cylinder Engine.</p></div>
+
+<p>It is obvious by consideration of the foregoing that
+there can be no arbitrary rules established for timing,<span class='pagenum'><a name="Page_276" id="Page_276">[276]</a></span>
+because of the many conditions which determine the best
+times for opening and closing the valves. It is customary
+to try various settings when a new motor is designed
+until the most satisfactory points are determined, and
+the setting which will be very suitable for one motor is
+not always right for one of different design. The timing
+diagram shown at <a href="#Fig108">Fig. 108</a> applies to the Hall-Scott
+engine, and may be considered typical. It should be
+easily followed in view of the very complete explanation
+given in preceding pages. Another six-cylinder engine
+diagram is shown at <a href="#Fig109">Fig. 109</a>, and an eight-cylinder timing
+diagram is shown at <a href="#Fig110">Fig. 110</a>. In timing automobile
+engines no trouble is experienced, because timing marks<span class='pagenum'><a name="Page_277" id="Page_277">[277]</a></span>
+are always indicated on the engine fly-wheel register with
+an indicating trammel on the crank-case. To time an
+airplane engine accurately, as is necessary to test for a
+suspected cam-shaft defect, a timing disc of aluminum is
+attached to the crank-shaft which has the timing marks
+indicated thereon. If the disc is made 10 or 12 inches
+in diameter, it may be divided into degrees without
+difficulty.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig110" id="Fig110"></a>
+<img src="images/illo271.png" alt="Fig. 110" width="450" height="447" />
+<p class="caption">Fig. 110.&mdash;Timing Diagram of Typical Eight-Cylinder V Engine.</p></div>
+
+<h3><a name="SecVIII_20" id="SecVIII_20"></a>HOW AN ENGINE IS TIMED</h3>
+
+<p>In timing a motor from the marks on the timing disc
+rim it is necessary to regulate the valves of but one
+cylinder at a time. Assuming that the disc is revolving
+in the direction of engine rotation, and that the firing
+order of the cylinders is 1-3-4-2, the operation of timing
+would be carried on as follows: The crank-shaft would
+be revolved until the line marked &#8220;Exhaust opens 1 and
+4&#8221; registered with the trammel on the motor bed. At this
+point the exhaust-valve of either cylinder No. 1 or No. 4
+should begin to open. This can be easily determined by
+noting which of these cylinders holds the compressed
+charge ready for ignition. Assuming that the spark has
+occurred in cylinder No. 1, then when the fly-wheel is
+turned from the position to that in which the line marked
+&#8220;Exhaust opens 1 and 4&#8221; coincides with the trammel
+point, the valve-plunger under the exhaust-valve of cylinder
+No. 1 should be adjusted in such a way that there is
+no clearance between it and the valve stem. Further
+movement of the wheel in the same direction should produce
+a lift of the exhaust valve. The disc is turned about
+two hundred and twenty-five degrees, or a little less than
+three-quarters of a revolution; then the line marked
+&#8220;Exhaust closes 1 and 4&#8221; will register with the trammel
+point. At this period the valve-plunger and the valve-stem
+should separate and a certain amount of clearance
+obtain between them. The next cylinder to time would
+be No. 3. The crank-shaft is rotated until mark &#8220;Exhaust
+opens 2 and 3&#8221; comes in line with the trammel. At this<span class='pagenum'><a name="Page_278" id="Page_278">[278]</a></span>
+point the exhaust valve of cylinder No. 3 should be just
+about opening. The closing is determined by rotating the
+shaft until the line &#8220;Exhaust closes 2 and 3&#8221; comes
+under the trammel.</p>
+
+<p>This operation is carried on with all the cylinders,
+it being well to remember that but one cylinder is working
+at a time and that a half-revolution of the fly-wheel
+corresponds to a full working stroke of all the cylinders,
+and that while one is exhausting the others are respectively
+taking in a new charge, compressing and exploding.
+For instance, if cylinder No. 1 has just completed its
+power-stroke, the piston in cylinder No. 3 has reached
+the point where the gas may be ignited to advantage.
+The piston of cylinder No. 4, which is next to fire, is at
+the bottom of its stroke and will have inspired a charge,
+while cylinder No. 2, which is the last to fire, will have
+just finished expelling a charge of burned gas, and will
+be starting the intake stroke. This timing relates to a
+four-cylinder engine in order to simplify the explanation.
+The timing instructions given apply only to the conventional
+motor types. Rotary cylinder engines, especially
+the Gnome &#8220;monosoupape,&#8221; have a distinctive valve
+timing on account of the peculiarities of design.</p>
+
+<h3><a name="SecVIII_21" id="SecVIII_21"></a>GNOME &#8220;MONOSOUPAPE&#8221; VALVE TIMING</h3>
+
+<p>In the present design of the Gnome motor, a cycle of
+operations somewhat different from that employed in the
+ordinary four-cycle engine is made use of, says a writer
+in &#8220;The Automobile,&#8221; in describing the action of this
+power-plant. This cycle does away with the need for the
+usual inlet valve and makes the engine operable with only
+a single valve, hence the name <i>monosoupape</i>, or &#8220;single-valve.&#8221;
+The cycle is as follows: A charge being compressed
+in the outer end of the cylinder or combustion
+chamber, it is ignited by a spark produced by the spark-plug
+located in the side of this chamber, and the burning
+charge expands as the piston moves down in the cylinder
+while the latter revolves around the crank-shaft. When<span class='pagenum'><a name="Page_279" id="Page_279">[279]</a></span>
+the piston is about half-way down on the power stroke,
+the exhaust valve, which is located in the center of the
+cylinder-head, is mechanically opened, and during the
+following upstroke of the piston the burnt gases are
+expelled from the cylinder through the exhaust valve
+directly into the atmosphere.</p>
+
+<p>Instead of closing at the end of the exhaust stroke,
+or a few degrees thereafter, the exhaust valve is held
+open for about two-thirds of the following inlet stroke
+of the piston, with the result that fresh air is drawn
+through the exhaust valve into the cylinder. When the
+cylinder is still 65 degrees from the end of the inlet half-revolution,
+the exhaust valve closes. As no more air
+can get into the cylinder, and as the piston continues to
+move inwardly, it is obvious that a partial vacuum is
+formed.</p>
+
+<p>When the cylinder approaches within 20 degrees of
+the end of the inlet half-revolution a series of small
+inlet ports all around the circumference of the cylinder
+wall is uncovered by the top edge of the piston, whereby
+the combustion chamber is placed in communication with
+the crank chamber. As the pressure in the crank chamber
+is substantially atmospheric and that in the combustion
+chamber is below atmospheric, there results a suction
+effect which causes the air from the crank chamber to
+flow into the combustion chamber. The air in the crank
+chamber is heavily charged with gasoline vapor, which
+is due to the fact that a spray nozzle connected with the
+gasoline supply tank is located inside the chamber. The
+proportion of gasoline vapor in the air in the crank
+chamber is several times as great as in the ordinary
+combustible mixture drawn from a carburetor into the
+cylinder. This extra-rich mixture is diluted in the combustion
+chamber with the air which entered it through
+the exhaust valve during the first part of the inlet stroke,
+thus forming a mixture of the proper proportion for
+complete combustion.</p>
+
+<p>The inlet ports in the cylinder wall remain open until<span class='pagenum'><a name="Page_280" id="Page_280">[280]</a></span>
+20 degrees of the compression half-revolution has been
+completed, and from that moment to near the end of the
+compression stroke the gases are compressed in the
+cylinder. Near the end of the stroke ignition takes place
+and this completes the cycle.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig111" id="Fig111"></a>
+<img src="images/illo276.png" alt="Fig. 111" width="400" height="416" />
+<p class="caption">Fig. 111.&mdash;Timing Diagram Showing Peculiar Valve Timing of Gnome
+&#8220;Monosoupape&#8221; Rotary Motor.</p></div>
+
+<p>The exact timing of the different phases of the cycle
+is shown in the diagram at <a href="#Fig111">Fig. 111</a>. It will be seen that
+ignition occurs substantially 20 degrees ahead of the
+outer dead center, and expansion of the burning gases
+continues until 85 degrees past the outer dead center,
+when the piston is a little past half-stroke. Then the
+exhaust-valve opens and remains open for somewhat
+more than a complete revolution of the cylinders, or, to
+be exact, for 390 degrees of cylinder travel, until 115
+degrees past the top dead center on the second revolution.
+Then for 45 degrees of travel the charge within the
+cylinder is expanded, whereupon the inlet ports are uncovered
+and remain open for 40 degrees of cylinder
+travel, 20 degrees on each side of the inward dead center
+position.</p>
+
+<h3><a name="SecVIII_22" id="SecVIII_22"></a>SPRINGLESS VALVES</h3>
+
+<p>Springless valves are the latest development on French
+racing car engines, and it is possible that the positively-operated
+types will be introduced on aviation engines
+also. Two makes of positively-actuated valves are shown
+at <a href="#Fig112">Fig. 112</a>. The positive-valve motor differs from the conventional
+form by having no necessity for valve-springs,
+as a cam not only assures the opening of the valve, but
+also causes it to return to the valve-seat. In this respect
+it is much like the sleeve-valve motor, where the uncovering
+of the ports is absolutely positive. The cars equipped
+with these valves were a success in long-distance auto
+races. Claims made for this type of valve mechanism
+include the possibility of a higher number of revolutions
+and consequently greater engine power. With the spring-controlled,
+single-cam operated valve a point is reached
+where the spring is not capable of returning the valve<span class='pagenum'><a name="Page_281" id="Page_281">[281]</a></span>
+to its seat before the cam has again begun its opening
+movement. It is possible to extend the limits considerably
+by using a light valve on a strong spring, but the
+valve still remains a limiting factor in the speed of the
+motor.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig112" id="Fig112"></a>
+<img src="images/illo277.png" alt="Fig. 112" width="500" height="414" />
+<p class="caption">Fig. 112.&mdash;Two Methods of Operating Valves by Positive Cam Mechanism
+Which Closes as Well as Opens Them.</p></div>
+
+<p>A part sectional view through a cylinder of an engine
+designed by G. Michaux is shown at <a href="#Fig112">Fig. 112</a>, A. There
+are two valves per cylinder, inclined at about ten degrees
+from the vertical. The valve-stems are of large diameter,
+as owing to positive control, there is no necessity of
+lightening this part in an unusual degree. A single overhead<span class='pagenum'><a name="Page_282" id="Page_282">[282]</a></span>
+cam-shaft has eight pairs of cams, which are shown
+in detail at B. For each valve there is a three-armed
+rocker, one arm of which is connected to the stem of the
+valve and the two others are in contact respectively with
+the opening and closing cams. The connection to the
+end of the valve-stem is made by a short connecting link,
+which is screwed on to the end of the valve-stem and
+locked in position. This allows some adjustment to be
+made between the valves and the actuating rocker. It will
+be evident that one cam and one rocker arm produce
+the opening of the valve and that the corresponding
+rocker arm and cam result in the closing of the valve.
+If the opening cam has the usual convex profile, the closing
+cam has a correspondingly concave profile. It will
+be noticed that a light valve-spring is shown in drawing.
+This is provided to give a final seating to its valve after<span class='pagenum'><a name="Page_283" id="Page_283">[283]</a></span>
+it has been closed by the cam. This is not absolutely
+necessary, as an engine has been run successfully without
+these springs. The whole mechanism is contained
+within an overhead aluminum cover.</p>
+
+<p>The positive-valve system used on the De Lage motor
+is shown at D. In this the valves are actuated as shown
+in sectional views D and E. The valve system is unique
+in that four valves are provided per cylinder, two for
+exhaust and two for intake. The valves are mounted
+side by side, as shown at E, so the double actuator member
+may be operated by a single set of cams. The valve-operating
+member consists of a yoke having guide bars
+at the top and bottom. The actuating cam works inside
+of this yoke. The usual form of cam acts on the lower
+portion of the yoke to open the valve, while the concave
+cam acts on the upper part to close the valves. In this
+design provision is made for expansion of the valve-stems
+due to heat, and these are not positively connected to the
+actuating member. As shown at E, the valves are held
+against the seat by short coil springs at the upper end
+of the stem. These are very stiff and are only intended
+to provide for expansion. A slight space is left between
+the top of the valve-stem and the portion of the operating
+member that bears against them when the regular
+profile cam exerts its pressure on the bottom of the valve-operating
+mechanism. Another novelty in this motor
+design is that the cam-shafts and the valve-operating
+members are carried in casing attached above the motor
+by housing supports in the form of small steel pillars.
+The overhead cam-shafts are operated by means of bevel
+gearing.</p>
+
+<h3><a name="SecVIII_23" id="SecVIII_23"></a>FOUR VALVES PER CYLINDER</h3>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig113" id="Fig113"></a>
+<img src="images/illo279.png" alt="Fig. 113" width="450" height="349" />
+<p class="caption">Fig. 113.&mdash;Diagram Comparing Two Large Valves and Four Small Ones
+of Practically the Same Area. Note How Easily Small Valves are
+Installed to Open Directly Into the Cylinder.</p></div>
+
+<p>Mention has been previously made of the sixteen-valve
+four-cylinder Duesenberg motor and its great power
+output for the piston displacement. This is made possible
+by the superior volumetric efficiency of a motor
+provided with four valves in each cylinder instead of<span class='pagenum'><a name="Page_284" id="Page_284">[284]</a></span>
+but two. This principle was thoroughly tried out in racing
+automobile motors, and is especially valuable in permitting
+of greater speed and power output from simple
+four- and six-cylinder engines. On eight- and twelve-cylinder
+types, it is doubtful if the resulting complication
+due to using a very large number of valves would
+be worth while. When extremely large valves are used,
+as shown in diagram at <a href="#Fig113">Fig. 113</a>, it is difficult to have
+them open directly into the cylinder, and pockets are
+sometimes necessary. A large valve would weigh more
+than two smaller valves having an area slightly larger
+in the aggregate; it would require a stiffer valve spring
+on account of its greater weight. A certain amount of
+metal in the valve-head is necessary to prevent warping;
+therefore, the inertia forces will be greater in the large
+valve than in the two smaller valves. As a greater port<span
+class='pagenum'><a name="Page_286" id="Page_286">[286]</a></span><span class='pagenum'><a name="Page_285" id="Page_285"></a></span>
+area is obtained by the use of two valves, the gases will
+be drawn into the cylinder or expelled faster than with
+a lesser area. Even if the areas are practically the same
+as in the diagram at <a href="#Fig113">Fig. 113</a>, the smaller valves may
+have a greater lift without imposing greater stresses on
+the valve-operating mechanism and quicker gas intake
+and exhaust obtained. The smaller valves are not affected
+by heat as much as larger ones are. The quicker
+gas movements made possible, as well as reduction of<span class='pagenum'><a name="Page_287" id="Page_287">[287]</a></span>
+inertia forces, permits of higher rotative speed, and,
+consequently, greater power output for a given piston
+displacement. The drawings at <a href="#Fig114">Fig. 114</a> show a sixteen-valve
+motor of the four-cylinder type that has been designed
+for automobile racing purposes, and it is apparent
+that very slight modifications would make it suitable for
+aviation purposes. Part of the efficiency is due to the
+reduction of bearing friction by the use of ball bearings,
+but the multiple-valve feature is primarily responsible
+for the excellent performance.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig114" id="Fig114"></a>
+<img src="images/illo280.png" alt="Fig. 114" width="600" height="397" />
+<p class="caption">Fig. 114.&mdash;Sectional Views of Sixteen-Valve Four-Cylinder Automobile Racing Engine That May Have
+Possibilities for Aviation Service.</p></div>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig115" id="Fig115"></a>
+<img src="images/illo281.jpg" alt="Fig. 115" width="450" height="502" />
+<p class="caption">Fig. 115.&mdash;Front View of Curtiss OX-3 Aviation Motor, Showing Unconventional
+Valve Action by Concentric Push Rod and Pull Tube.</p></div>
+
+<hr class="c25" />
+<p class='pagenum'><a name="Page_288" id="Page_288">[288]</a></p>
+<h2><a name="ChIX" id="ChIX"></a>CHAPTER IX</h2>
+
+<div class="chapsec"><p><a href="#SecIX_1">Constructional Details of Pistons</a>&mdash;<a href="#SecIX_2">Aluminum Cylinders and
+Pistons</a>&mdash;<a href="#SecIX_3">Piston Ring Construction</a>&mdash;<a href="#SecIX_4">Leak Proof Piston Rings</a>&mdash;<a
+href="#SecIX_5">Keeping Oil Out of Combustion Chamber</a>&mdash;<a href="#SecIX_6">Connecting Rod Forms</a>&mdash;<a
+href="#SecIX_7">Connecting Rods for Vee Engines</a>&mdash;<a href="#SecIX_8">Cam-Shaft and Crank-Shaft Designs</a>&mdash;<a
+href="#SecIX_9">Ball Bearing Crank-Shafts</a>&mdash;<a href="#SecIX_10">Engine Base Construction</a>.</p></div>
+
+<h3><a name="SecIX_1" id="SecIX_1"></a>CONSTRUCTIONAL DETAILS OF PISTONS</h3>
+
+<p>The piston is one of the most important parts of the
+gasoline motor inasmuch as it is the reciprocating member
+that receives the impact of the explosion and which
+transforms the power obtained by the combustion of gas
+to mechanical motion by means of the connecting rod to
+which it is attached. The piston is one of the simplest
+elements of the motor, and it is one component which
+does not vary much in form in different types of motors.
+The piston is a cylindrical member provided with a series
+of grooves in which packing rings are placed on the outside
+and two bosses which serve to hold the wrist pin in
+its interior. It is usually made of cast iron or aluminum,
+though in some motors where extreme lightness is desired,
+such as those used for a&euml;ronautic work, it may be
+made of steel. The use of the more resisting material
+enables the engineer to use lighter sections where it is
+important that the weight of this member be kept as low
+as possible consistent with strength.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig116" id="Fig116"></a>
+<img src="images/illo284.png" alt="Fig. 116" width="450" height="348" />
+<p class="caption">Fig. 116.&mdash;Forms of Pistons Commonly Employed in Gasoline Engines.
+A&mdash;Dome Head Piston and Three Packing Rings. B&mdash;Flat Top Form
+Almost Universally Used. C&mdash;Concave Piston Utilized in Knight
+Motors and Some Having Overhead Valves. D&mdash;Two-Cycle Engine
+Member with Deflector Plate Cast Integrally. E&mdash;Differential of
+Two-Diameter Piston Used in Some Engines Operating on Two-Cycle
+Principle.</p></div>
+
+<p>A number of piston types are shown at <a href="#Fig116">Fig. 116</a>. That
+at A has a round top and is provided with four split
+packing rings and two oil grooves. A piston of this type
+is generally employed in motors where the combustion
+chamber is large and where it is desired to obtain a
+higher degree of compression than would be possible with
+a flat top piston. This construction is also stronger because
+of the arched piston top. The most common form<span class='pagenum'><a name="Page_289" id="Page_289">[289]</a></span>
+of piston is that shown at B, and it differs from that
+previously described only in that it has a flat top. The
+piston outlined in section at C is a type used on some
+of the sleeve-valve motors of the Knight pattern, and
+has a concave head instead of the convex form shown
+at A. The design shown at D in side and plan views is
+the conventional form employed in two-cycle engines.
+The deflector plate on the top of the cylinder is cast integral
+and is utilized to prevent the incoming fresh gases
+from flowing directly over the piston top and out of the
+exhaust port, which is usually opposite the inlet opening.
+On these types of two-cycle engines where a two-diameter
+cylinder is employed, the piston shown at E is<span class='pagenum'><a
+name="Page_291" id="Page_291">[291]</a></span><span class='pagenum'><a name="Page_290" id="Page_290"></a></span>
+used. This is known as a &#8220;differential piston,&#8221; and has
+an enlarged portion at its lower end which fits the pumping
+cylinder. The usual form of deflector plate is provided
+at the top of the piston and one may consider it
+as two pistons in one.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig117" id="Fig117"></a>
+<img src="images/illo285.png" alt="Fig. 117" width="600" height="372" />
+<p class="caption">Fig. 117.&mdash;Typical Methods of Piston Pin Retention Generally Used in Engines of American Design. A&mdash;Single
+Set Screw and Lock Nut. B&mdash;Set Screw and Check Nut Fitting Groove in Wrist Pin. C, D&mdash;Two Locking
+Screws Passing Into Interior of Hollow Wrist Pin. E&mdash;Split Ring Holds Pin in Place. F&mdash;Use of Taper Expanding
+Plugs Outlined. G&mdash;Spring Pressed Plunger Type. H&mdash;Piston Pin Pinned to Connecting Rod. I&mdash;Wrist
+Pin Clamped in Connecting Rod Small End by Bolt.</p></div>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig118" id="Fig118"></a>
+<img src="images/illo286.png" alt="Fig. 118" width="450" height="554" />
+<p class="caption">Fig. 118.&mdash;Typical Piston and Connecting Rod Assembly.</p></div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig119" id="Fig119"></a>
+<img src="images/illo287.png" alt="Fig. 119" width="400" height="514" />
+<p class="caption">Fig. 119.&mdash;Parts of Sturtevant Aviation Engine. A&mdash;Cylinder Head
+Showing Valves. B&mdash;Connecting Rod. C&mdash;Piston and Rings.</p></div>
+
+<p>One of the important conditions in piston design is
+the method of securing the wrist pin which is used to<span class='pagenum'><a name="Page_292" id="Page_292">[292]</a></span>
+connect the piston to the upper end of the connecting
+rod. Various methods have been devised to keep the
+pin in place, the most common of these being shown at
+<a href="#Fig117">Fig. 117</a>. The wrist pin should be retained by some
+positive means which is not liable to become loose under
+the vibratory stresses which obtain at this point. If the<span class='pagenum'><a name="Page_293" id="Page_293">[293]</a></span>
+wrist pin was free to move it would work out of the
+bosses enough so that the end would bear against the
+cylinder wall. As it is usually made of steel, which is a
+harder material than cast iron used in cylinder construction,
+the rubbing action would tend to cut a groove in
+the cylinder wall which would make for loss of power
+because it would permit escape of gas. The wrist pin
+member is a simple cylindrical element that fits the bosses
+closely, and it may be either hollow or solid stock. A
+typical piston and connecting rod assembly which shows
+a piston in section also is given at <a href="#Fig118">Fig. 118</a>. The piston
+of the Sturtevant a&euml;ronautical motor is shown at <a href="#Fig119">Fig.
+119</a>, the aluminum piston of the Thomas airplane motor
+with piston rings in place is shown at <a href="#Fig120">Fig. 120</a>. A good
+view of the wrist pin and connecting rod are also given.
+The iron piston of the Gnome &#8220;Monosoupape&#8221; airplane
+engine and the unconventional connecting rod assembly
+are clearly depicted at <a href="#Fig121">Fig 121</a>.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig120" id="Fig120"></a>
+<img src="images/illo288.jpg" alt="Fig. 120" width="600" height="378" />
+<p class="caption">Fig. 120.&mdash;Aluminum Piston and Light But Strong Steel Connecting Rod
+and Wrist Pin of Thomas Aviation Engine.</p></div>
+
+<p>The method of retention shown at A is the simplest
+and consists of a set screw having a projecting portion<span class='pagenum'><a name="Page_294" id="Page_294">[294]</a></span>
+passing into the wrist pin and holding it in place. The
+screw is kept from turning or loosening by means of a
+check nut. The method outlined at B is similar to that
+shown at A, except that the wrist pin is solid and the
+point of the set screw engages an annular groove turned
+in the pin for its reception. A very positive method is
+shown at C. Here the retention screws pass into the
+wrist pin and are then locked by a piece of steel wire
+which passes through suitable holes in the ends. The
+method outlined at D is sometimes employed, and it varies
+from that shown at C only in that the locking wire, which
+is made of spring steel, is passed through the heads of
+the locking screws. Some designers machine a large
+groove around the piston at such a point that when the
+wrist pin is put in place a large packing ring may be
+sprung in the groove and utilized to hold the wrist pin
+in place.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig121" id="Fig121"></a>
+<img src="images/illo289.jpg" alt="Fig. 121" width="600" height="270" />
+<p class="caption">Fig. 121.&mdash;Cast Iron Piston of &#8220;Monosoupape&#8221; Gnome Engine Installed
+On One of the Short Connecting Rods.</p></div>
+
+<p>The system shown at F is not so widely used as the
+simpler methods, because it is more costly and does not
+offer any greater security when the parts are new than
+the simple lock shown at A. In this a hollow wrist pin is
+used, having a tapered thread cut at each end. The wrist
+pin is slotted at three or four points, for a distance equal
+to the length of the boss, and when taper expansion plugs<span class='pagenum'><a name="Page_295" id="Page_295">[295]</a></span>
+are screwed in place the ends of the wrist pin are expanded
+against the bosses. This method has the advantage
+of providing a certain degree of adjustment if the
+wrist pin should loosen up after it has been in use for
+some time. The taper plugs would be screwed in deeper
+and the ends of the wrist pin expanded proportionately
+to take up the loss motion. The method shown at G is
+an ingenious one. One of the piston bosses is provided
+with a projection which is drilled out to receive a plunger.
+The wrist pin is provided with a hole of sufficient size to
+receive the plunger, which is kept in place by means of
+a spring in back of it. This makes a very positive lock
+and one that can be easily loosened when it is desired to
+remove the wrist pin. To unlock, a piece of fine rod is
+thrust into the hole at the bottom of the boss which pushes
+the plunger back against the spring until the wrist pin
+can be pushed out of the piston.</p>
+
+<p>Some engineers think it advisable to oscillate the wrist
+pin in the piston bosses, instead of in the connecting rod
+small end. It is argued that this construction gives more
+bearing surface at the wrist pin and also provides for
+more strength because of the longer bosses that can be
+used. When this system is followed the piston pin is
+held in place by locking it to the connecting rod by some
+means. At H the simplest method is outlined. This consisted
+of driving a taper pin through both rod and wrist
+pin and then preventing it from backing out by putting
+a split cotter through the small end of the tapered locking
+pin. Another method, which is depicted at I, consists
+of clamping the wrist pin by means of a suitable bolt
+which brings the slit connecting rod end together as
+shown.</p>
+
+<h3><a name="SecIX_2" id="SecIX_2"></a>ALUMINUM FOR CYLINDERS AND PISTONS</h3>
+
+<p>Aluminum pistons outlined at <a href="#Fig122">Fig. 122</a>, have replaced
+cast iron members in many airplane engines, as these
+weigh about one-third as much as the cast iron forms of
+the same size, while the reduction in the inertia forces<span class='pagenum'><a name="Page_296" id="Page_296">[296]</a></span>
+has made it possible to increase the engine speed without
+correspondingly stressing the connecting rods, crank-shaft
+and engine bearings.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig122" id="Fig122"></a>
+<img src="images/illo291.png" alt="Fig. 122" width="450" height="335" />
+<p class="caption">Fig. 122.&mdash;Types of Aluminum Pistons Used In Aviation Engines.</p></div>
+
+<p>Aluminum has not only been used for pistons, but a
+number of motors will be built for the coming season that
+will use aluminum cylinder block castings as well. Of
+course, the aluminum alloy is too soft to be used as a
+bearing for the piston, and it will not withstand the hammering
+action of the valve. This makes the use of cast
+iron or steel imperative in all motors. When used in connection
+with an aluminum cylinder block the cast iron
+pieces are placed in the mould so that they act as cylinder
+liners and valve seats, and the molten metal is poured
+around them when the cylinder is cast. It is said that
+this construction results in an intimate bond between the
+cast iron and the surrounding aluminum metal. Steel
+liners may also be pressed into the aluminum cylinders
+after these are bored out to receive them. Aluminum
+has for a number of years been used in many motor<span class='pagenum'><a name="Page_297" id="Page_297">[297]</a></span>
+car parts. Alloys have been developed that have greater
+strength than cast iron and that are not so brittle. Its
+use for manifolds and engine crank and gear cases has
+been general for a number of years.</p>
+
+<p>At first thought it would seem as though aluminum
+would be entirely unsuited for use in those portions of
+internal combustion engines exposed to the heat of the
+explosion, on account of the low melting point of that
+metal and its disadvantageous quality of suddenly &#8220;wilting&#8221;
+when a critical point in the temperature is reached.
+Those who hesitated to use aluminum on account of this
+defect lost sight of the great heat conductivity of that
+metal, which is considerably more than that of cast iron.
+It was found in early experiments with aluminum pistons
+that this quality of quick radiation meant that aluminum
+pistons remained considerably cooler than cast iron ones
+in service, which was attested to by the reduced formation
+of carbon deposit thereon. The use of aluminum
+makes possible a marked reduction in power plant weight.
+A small four-cylinder engine which was not particularly
+heavy even with cast iron cylinders was found to weigh
+100 pounds less when the cylinder block, pistons, and
+upper half of the crank-case had been made of aluminum
+instead of cast iron. Aluminum motors are no longer
+an experiment, as a considerable number of these have
+been in use on cars during the past year without the
+owners of the cars being apprised of the fact. Absolutely
+no complaint was made in any case of the aluminum
+motor and it was demonstrated, in addition to the saving
+in weight, that the motors cost no more to assemble and
+cooled much more efficiently than the cast iron form. One
+of the drawbacks to the use of aluminum is its growing
+scarcity, which results in making it a &#8220;near precious&#8221;
+metal.</p>
+
+<h3><a name="SecIX_3" id="SecIX_3"></a>PISTON RING CONSTRUCTION</h3>
+
+<p>As all pistons must be free to move up and down in
+the cylinder with minimum friction, they must be less in<span class='pagenum'><a name="Page_298" id="Page_298">[298]</a></span>
+diameter than the bore of the cylinder. The amount of
+freedom or clearance provided varies with the construction
+of the engine and the material the piston is made of,
+as well as its size, but it is usual to provide from .005 to
+.010 of an inch to compensate for the expansion of the
+piston due to heat and also to leave sufficient clearance
+for the introduction of lubricant between the working
+surfaces. Obviously, if the piston were not provided with
+packing rings, this amount of clearance would enable a
+portion of the gases evolved when the charge is exploded
+to escape by it into the engine crank-case. The packing
+members or piston rings, as they are called, are split
+rings of cast iron, which are sprung into suitable grooves
+machined on the exterior of the piston, three or four of
+these being the usual number supplied. These have sufficient
+elasticity so that they bear tightly against the cylinder
+wall and thus make a gas-tight joint. Owing to the
+limited amount of surface in contact with the cylinder
+wall and the elasticity of the split rings the amount of
+friction resulting from the contact of properly fitted rings
+and the cylinder is not of enough moment to cause any
+damage and the piston is free to slide up and down in
+the cylinder bore.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig123" id="Fig123"></a>
+<img src="images/illo293.png" alt="Fig. 123" width="450" height="169" />
+<p class="caption">Fig. 123.&mdash;Types of Piston Rings and Ring Joints. A&mdash;Concentric Ring.
+B&mdash;Eccentrically Machined Form. C&mdash;Lap Joint Ring. D&mdash;Butt Joint,
+Seldom Used. E&mdash;Diagonal Cut Member, a Popular Form.</p></div>
+
+<p>These rings are made in two forms, as outlined at
+<a href="#Fig123">Fig. 123</a>. The design shown at A is termed a
+&#8220;concentric<span class='pagenum'><a name="Page_299" id="Page_299">[299]</a></span>
+ring,&#8221; because the inner circle is concentric with the
+outer one and the ring is of uniform thickness at all
+points. The ring shown at B is called an &#8220;eccentric
+ring,&#8221; and it is thicker at one part than at others. It
+has theoretical advantages in that it will make a tighter
+joint than the other form, as it is claimed its expansion
+due to heat is more uniform. The piston rings must be
+split in order that they may be sprung in place in the
+grooves, and also to insure that they will have sufficient
+elasticity to take the form of the cylinder at the different
+points in their travel. If the cylinder bore varies by
+small amounts the rings will spring out at the points
+where the bore is larger than standard, and spring in at
+those portions where it is smaller than standard.</p>
+
+<p>It is important that the joint should be as nearly gas-tight
+as possible, because if it were not a portion of the
+gases would escape through the slots in the piston rings.
+The joint shown at C is termed a &#8220;lap joint,&#8221; because
+the ends of the ring are cut in such a manner that they
+overlap. This is the approved joint. The butt joint
+shown at D is seldom used and is a very poor form, the
+only advantage being its cheapness. The diagonal cut
+shown at E is a compromise between the very good form
+shown at C and the poor joint depicted at D. It is also
+widely used, though most constructors prefer the lap
+joint, because it does not permit the leakage of gas as
+much as the other two types.</p>
+
+<p>There seems to be some difference of opinion relative
+to the best piston ring type&mdash;some favoring the eccentric
+pattern, others the concentric form. The concentric ring
+has advantages from the lubricating engineer&#8217;s point of
+view; as stated by the Platt &amp; Washburn Company in
+their text-book on engine lubrication, the smaller clearance
+behind the ring possible with the ring of uniform
+section is advantageous.</p>
+
+<p><a href="#Fig124">Fig. 124</a>, A, shows a concentric piston ring in its
+groove. Since the ring itself is concentric with the
+groove, very small clearance between the back of the ring<span class='pagenum'><a name="Page_300" id="Page_300">[300]</a></span>
+and the bottom of its groove may be allowed. Small
+clearance leaves less space for the accumulation of oil
+and carbon deposits. The gasket effect of this ring is
+uniform throughout the entire length of its edges, which
+is its marked advantage over the eccentric ring. This
+type of piston ring rarely burns fast in its groove. There
+are a large number of different concentric rings manufactured
+of different designs and of different efficiency.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig124" id="Fig124"></a>
+<img src="images/illo295.png" alt="Fig. 124" width="500" height="254" />
+<p class="caption">Fig. 124.&mdash;Diagrams Showing Advantages of Concentric Piston Rings.</p></div>
+
+<p><a href="#Fig124">Figs. 124</a>, B and <a href="#Fig124">124</a>, C show eccentric rings assembled
+in the ring groove. It will be noted that there is a large
+space between the thin ends of this ring and the bottom
+of the groove. This empty space fills up with oil which
+in the case of the upper ring frequently is carbonized,
+restricting the action of the ring and nullifying its usefulness.
+The edges of the thin ends are not sufficiently
+wide to prevent rapid escape of gases past them. In a
+practical way this leakage means loss of compression and
+noticeable drop in power. When new and properly fitted,
+very little difference can be noted between the tightness
+of eccentric and concentric rings. Nevertheless, after
+several months&#8217; use, a more rapid leakage will always
+occur past the eccentric than past the concentric. If
+continuous trouble with the carbonization of cylinders,
+smoking and sooting of spark-plugs is experienced, it is<span class='pagenum'><a name="Page_301" id="Page_301">[301]</a></span>
+a sure indication that mechanical defects exist in the engine,
+assuming of course, that a suitable oil has been
+used. Such trouble can be greatly lessened, if not entirely
+eliminated, by the application of concentric rings
+(lap joint), of any good make, properly fitted into the
+grooves of the piston. Too much emphasis cannot be
+put upon this point. If the oil used in the engine is of
+the correct viscosity, and serious carbon deposit, smoking,
+etc., still result, the only certain remedy then is to have
+the cylinders rebored and fitted with properly designed,
+oversized pistons and piston rings.</p>
+
+<h3><a name="SecIX_4" id="SecIX_4"></a>LEAK-PROOF PISTON RINGS</h3>
+
+<p>In order to reduce the compression loss and leakage
+of gas by the ordinary simple form of diagonal or lap
+joint one-piece piston ring a number of compound rings
+have been devised and are offered by their makers to
+use in making replacements. The leading forms are
+shown at <a href="#Fig125">Fig. 125</a>. That shown at A is known as the
+&#8220;Statite&#8221; and consists of three rings, one carried inside
+while the other two are carried on the outside. The ring
+shown at B is a double ring and is known as the McCadden.
+This is composed of two thin concentric lap joint
+rings so disposed relative to each other that the opening
+in the inner ring comes opposite to the opening in the
+outer ring.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig125" id="Fig125"></a>
+<img src="images/illo297.png" alt="Fig. 125" width="500" height="348" />
+<p class="caption">Fig. 125.&mdash;Leak-Proof and Other Compound Piston Rings.</p></div>
+
+<p>The form shown at C is known as the &#8220;Leektite,&#8221;
+and is a single ring provided with a peculiar form of lap
+and dove tail joint. The ring shown at D is known as
+the &#8220;Dunham&#8221; and is of the double concentric type being
+composed of two rings with lap joints which are welded
+together at a point opposite the joint so that there is no
+passage by which the gas can escape. The Burd high
+compression ring is shown at E. The joints of these
+rings are sealed by means of an H-shaped coupler of
+bronze which closes the opening. The ring ends are made
+with tongues which interlock with the coupling. The<span class='pagenum'><a name="Page_302" id="Page_302">[302]</a></span>
+ring shown at F is called the &#8220;Evertite&#8221; and is a three-piece
+ring composed of three members as shown in the
+sectional view below the ring. The main part or inner
+ring has a circumferential channel in which the two outer
+rings lock, the resulting cross-section being rectangular
+just the same as that of a regular pattern ring. All
+three rings are diagonally split and the joints are spaced
+equally and the distances maintained by small pins. This
+results in each joint being sealed by the solid portion of
+the other rings.</p>
+
+<p>The use of a number of light steel rings instead of
+one wide ring in the groove is found on a number of
+automobile power plants, but as far as known, this construction
+is not used in airplane power plants. It is
+contended that where a number of light rings is employed
+a more flexible packing means is obtained and the
+possibility of leakage is reduced. Rings of this design
+are made of square section steel wire and are given a
+spring temper. Owing to the limited width the diagonal<span class='pagenum'><a name="Page_303" id="Page_303">[303]</a></span>
+cut joint is generally employed instead of the lap joint
+which is so popular on wider rings.</p>
+
+<h3><a name="SecIX_5" id="SecIX_5"></a>KEEPING OIL OUT OF COMBUSTION CHAMBERS</h3>
+
+<p>An examination of the engine design that is economical
+in oil consumption discloses the use of tight piston
+rings, large centrifugal rings on the crank-shaft where it
+passes through the case, ample cooling fins in the pistons,
+vents between the crank-case chamber and the valve enclosures,
+etc. Briefly put, cooling of the oil in this engine
+has been properly cared for and leakage reduced to a
+minimum. To be specific regarding details of design:
+Oil surplus can be kept out of the explosion chambers by
+leaving the lower edge of the piston skirt sharp and by
+the use of a shallow groove (C), <a href="#Fig126">Fig. 126</a>, just below the
+lower piston ring. Small holes are bored through the
+piston walls at the base of this groove and communicate
+with the crank-case. The similarity of the sharp edges
+of piston skirt (D) and piston ring to a carpenter&#8217;s plane
+bit, makes their operation plain.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig126" id="Fig126"></a>
+<img src="images/illo299.png" alt="Fig. 126" width="400" height="462" />
+<p class="caption">Fig. 126.&mdash;Sectional View of Engine Showing Means of Preventing
+Oil Leakage By Piston Rings.</p></div>
+
+<p>The cooling of oil in the sump (A) can be accomplished
+most effectively by radiating fins on its outer
+surface. The lower crank-case should be fully exposed to
+the outer air. A settling basin for sediment (B) should
+be provided having a cubic content not less than one-tenth
+of the total oil capacity as outlined at <a href="#Fig126">Fig. 126</a>.
+The depth of this basin should be at least 2<sup>1</sup>&#8260;<sub>2</sub> inches, and
+its walls vertical, as shown, to reduce the mixing of sediment
+with the oil in circulation. The inlet opening to
+the oil pump should be near the top of the sediment basin
+in order to prevent the entrance into the pump with the
+oil of any solid matter or water condensed from the products
+of combustion. This sediment basin should be
+drained after every five to seven hours air service of an
+airplane engine. Concerning filtering screens there is
+little to be said, save that their areas should be ample
+and the mesh coarse enough (one-sixteenth of an inch) to<span class='pagenum'><a name="Page_304" id="Page_304">[304]</a></span>
+offer no serious resistance to the free flow of cold or
+heavy oil through them; otherwise the oil in the crank-case
+may build up above them to an undesirable level.
+The necessary frequency of draining and flushing out the
+oil sump differs greatly with the age (condition) of the
+engine and the suitability of the oil used. In broad terms,
+the oil sump of a new engine should be thoroughly drained
+and flushed with kerosene at the end of the first 200<span class='pagenum'><a name="Page_305" id="Page_305">[305]</a></span>
+miles, next at the end of 500 miles and thereafter every
+1,000 miles. While these instructions apply specifically
+to automobile motors, it is very good practice to change
+the oil in airplane engines frequently. In many cases,
+the best results have been secured when the oil supply
+is completely replenished every five hours that the engine
+is in operation.</p>
+
+<h3><a name="SecIX_6" id="SecIX_6"></a>CONNECTING ROD FORMS</h3>
+
+<p>The connecting rod is the simple member that joins
+the piston to the crank-shaft and which transmits the
+power imparted to the piston by the explosion so that it
+may be usefully applied. It transforms the reciprocating
+movement of the piston to a rotary motion at the crank-shaft.
+A typical connecting rod and its wrist pin are
+shown at <a href="#Fig120">Fig. 120</a>. It will be seen that it has two bearings,
+one at either end. The small end is bored out to
+receive the wrist pin which joins it to the piston, while
+the large end has a hole of sufficient size to go on the
+crank-pin. The airplane and automobile engine connecting
+rod is invariably a steel forging, though in marine
+engines it is sometimes made a steel or high tensile
+strength bronze casting. In all cases it is desirable to
+have softer metals than the crank-shaft and wrist pin at
+the bearing point, and for this reason the connecting rod
+is usually provided with bushings of anti-friction or white
+metal at the lower end, and bronze at the upper. The
+upper end of the connecting rod may be one piece, because
+the wrist pin can be introduced after it is in place
+between the bosses of the piston. The lower bearing
+must be made in two parts in most cases, because the
+crank-shaft cannot be passed through the bearing owing
+to its irregular form. The rods of the Gnome engine are
+all one piece types, as shown at <a href="#Fig127">Fig. 127</a>, owing to the
+construction of the &#8220;mother&#8221; rod which receives the
+crank-pins. The complete connecting rod assembly is
+shown in <a href="#Fig121">Fig. 121</a>, also at A, <a href="#Fig127">Fig. 127</a>.
+The &#8220;mother<span class='pagenum'><a name="Page_306" id="Page_306">[306]</a></span>&#8221;
+rod, with one of the other rods in place and one about
+to be inserted, is shown at <a href="#Fig127">Fig. 127</a>, B. The built-up
+crank-shaft which makes this construction feasible is
+shown at <a href="#Fig127">Fig. 127</a>, C.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig127" id="Fig127"></a>
+<img src="images/illo301.png" alt="Fig. 127" width="450" height="318" />
+<p class="caption">Fig. 127.&mdash;Connecting Rod and Crank-Shaft Construction of Gnome
+&#8220;Monosoupape&#8221; Engine.</p></div>
+
+<p>Some of the various designs of connecting rods that
+have been used are shown at <a href="#Fig128">Fig. 128</a>. That at A is a
+simple form often employed in single-cylinder motors,
+having built-up crank-shafts. Both ends of the connecting
+rod are bushed with a one-piece bearing, as it can
+be assembled in place before the crank-shaft assembly is
+built up. A built-up crank-shaft such as this type of connecting
+rod would be used with is shown at <a href="#Fig106">Fig. 106</a>. The
+pattern shown at B is one that has been used to some
+extent on heavy work, and is known as the &#8220;marine
+type.&#8221; It is made in three pieces, the main portion being
+a steel forging having a flanged lower end to which the
+bronze boxes are secured by bolts. The modified marine
+type depicted at C is the form that has received the widest
+application in automobile and aviation engine construction.<span
+class='pagenum'><a name="Page_308" id="Page_308">[308]</a></span><span class='pagenum'><a name="Page_307" id="Page_307"></a></span>
+It consists of two pieces, the main member
+being a steel drop forging having the wrist-pin bearing
+and the upper crank-pin bearing formed integral, while
+the lower crank-pin bearing member is a separate forging
+secured to the connecting rod by bolts. In this construction
+bushings of anti-friction metal are used at the
+lower end, and a bronze bushing is forced into the upper- or
+wrist-pin end. The rod shown at D has also been
+widely used. It is similar in construction to the form
+shown at C, except that the upper end is split in order
+to permit of a degree of adjustment of the wrist-pin
+bushing, and the lower bearing cap is a hinged member
+which is retained by one bolt instead of two. When it is
+desired to assemble it on the crank-shaft the lower cap
+is swung to one side and brought back into place when
+the connecting rod has been properly located. Sometimes
+the lower bearing member is split diagonally instead of
+horizontally, such a construction being outlined at E.</p>
+
+<div class="figcenter" style="width: 550px;"><a name="Fig128" id="Fig128"></a>
+<img src="images/illo302.png" alt="Fig. 128" width="550" height="344" />
+<p class="caption">Fig. 128.&mdash;Connecting Rod Types Summarized. A&mdash;Single Connecting Rod Made in One Piece, Usually Fitted in
+Small Single-Cylinder Engines Having Built-Up Crank-Shafts. B&mdash;Marine Type, a Popular Form on Heavy
+Engines. C&mdash;Conventional Automobile Type, a Modified Marine Form. D&mdash;Type Having Hinged Lower Cap
+and Split Wrist Pin Bushing. E&mdash;Connecting Rod Having Diagonally Divided Big End. F&mdash;Ball-Bearing Rod.
+G&mdash;Sections Showing Structural Shapes Commonly Employed in Connecting Rod Construction.</p></div>
+
+<p>In a number of instances, instead of plain bushed
+bearings anti-friction forms using ball or rollers have
+been used at the lower end. A ball-bearing connecting
+rod is shown at F. The big end may be made in one
+piece, because if it is possible to get the ball bearing on
+the crank-pins it will be easy to put the connecting rod
+in place. Ball bearings are not used very often on connecting
+rod big ends because of difficulty of installation,
+though when applied properly they give satisfactory service
+and reduce friction to a minimum. One of the advantages
+of the ball bearing is that it requires no adjustment,
+whereas the plain bushings depicted in the other
+connecting rods must be taken up from time to time to
+compensate for wear.</p>
+
+<p>This can be done in forms shown at B, C, D, and E
+by bringing the lower bearing caps closer to the upper
+one and scraping out the brasses to fit the shaft. A
+number of liners or shims of thin brass or copper stock,
+varying from .002 inch to .005 inch, are sometimes interposed
+between the halves of the bearings when it is first<span class='pagenum'><a name="Page_309" id="Page_309">[309]</a></span>
+fitted to the crank-pin. As the brasses wear the shims
+may be removed and the portions of the bearings brought
+close enough together to take up any lost motion that
+may exist, though in some motors no shims are provided
+and depreciation can be remedied only by installing new
+brasses and scraping to fit.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig129" id="Fig129"></a>
+<img src="images/illo304.png" alt="Fig. 129" width="450" height="347" />
+<p class="caption">Fig. 129.&mdash;Double Connecting Rod Assembly For Use On Single Crank-Pin
+of Vee Engine.</p></div>
+
+<p>The various structural shapes in which connecting rods
+are formed are shown in section at G. Of these the I
+section is most widely used in airplane engines, because
+it is strong and a very easy shape to form by the drop-forging
+process or to machine out of the solid bar when
+extra good steel is used. Where extreme lightness is
+desired, as in small high-speed motors used for cycle propulsion,
+the section shown at the extreme left is often
+used. If the rod is a cast member as in some marine engines,
+the cross, hollow cylinder, or U sections are sometimes
+used. If the sections shown at the right are employed,<span class='pagenum'><a name="Page_310" id="Page_310">[310]</a></span>
+advantage is often taken of the opportunity for
+passing lubricant through the center of the hollow round
+section on vertical motors or at the bottom of the U
+section, which would be used on a horizontal cylinder
+power plant.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig130" id="Fig130"></a>
+<img src="images/illo305.png" alt="Fig. 130" width="450" height="310" />
+<p class="caption">Fig. 130.&mdash;Another Type of Double Connecting Rod for Vee Engines.</p></div>
+
+<p><a name="SecIX_7" id="SecIX_7"></a>Connecting rods of Vee engines are made in two distinct
+styles. The forked or &#8220;scissors&#8221; joint rod assembly
+is employed when the cylinders are placed directly opposite
+each other. The &#8220;blade&#8221; rod, as shown at <a href="#Fig129">Fig.
+129</a>, fits between the lower ends of the forked rod, which
+oscillate on the bearing which encircles the crank-pin.
+The lower end of the &#8220;blade&#8221; rod is usually attached to
+the bearing brasses, the ends of the &#8220;forked&#8221; rod move
+on the outer surfaces of the brasses. Another form of
+rod devised for use under these conditions is shown at
+<a href="#Fig130">Fig. 130</a> and installed in an aviation engine at <a href="#Fig132">Fig. 132</a>.
+In this construction the shorter rod is attached to a boss
+on the master rod by a short pin to form a hinge and to
+permit the short rod to oscillate as the conditions dictate.<span class='pagenum'><a
+name="Page_312" id="Page_312">[312]</a></span><span class='pagenum'><a name="Page_311" id="Page_311"></a></span>
+This form of rod can be easily adjusted when the
+bearing depreciates, a procedure that is difficult with the
+forked type rod. The best practice, in the writer&#8217;s opinion,
+is to stagger the cylinders and use side-by-side rods
+as is done in the Curtiss engine. Each rod may be fitted
+independently of the other and perfect compensation for
+wear of the big ends is possible.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig131" id="Fig131"></a>
+<img src="images/illo306.png" alt="Fig. 131" width="600" height="397" />
+<p class="caption">Fig. 131.&mdash;Part Sectional View of Wisconsin Aviation Engine, Showing Four-Bearing Crank-Shaft, Overhead
+Cam-Shaft, and Method of Combining Cylinders in Pairs.</p></div>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig132" id="Fig132"></a>
+<img src="images/illo307.png" alt="Fig. 132" width="450" height="526" />
+<p class="caption">Fig. 132.&mdash;Part Sectional View of Renault Twelve-Cylinder Water-Cooled
+Engine, Showing Connecting Rod Construction and Other Important
+Internal Parts.</p></div>
+
+<p class='pagenum'><a name="Page_313" id="Page_313">[313]</a></p>
+
+<h3><a name="SecIX_8" id="SecIX_8"></a>CAM-SHAFT AND CRANK-SHAFT DESIGN</h3>
+
+<p>Before going extensively into the subject of crank-shaft
+construction it will be well to consider cam-shaft
+design, which is properly a part of the valve system and
+which has been considered in connection with the other
+elements which have to do directly with cylinder construction
+to some extent. Cam-shafts are usually simple members
+carried at the base of the cylinder in the engine
+case of Vee type motors by suitable bearings and having
+the cams employed to lift the valves attached at intervals.
+A typical cam-shaft design is shown at <a href="#Fig133">Fig. 133</a>. Two
+main methods of cam-shaft construction are followed&mdash;that
+in which the cams are separate members, keyed and
+pinned to the shaft, and the other where the cams are
+formed integral, the latter being the most suitable for
+airplane engine requirements.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig133" id="Fig133"></a>
+<img src="images/illo308.jpg" alt="Fig. 133" width="600" height="156" />
+<p class="caption">Fig. 133.&mdash;Typical Cam-Shaft, with Valve Lifting Cams and Gears to
+Operate Auxiliary Devices Forged Integrally.</p></div>
+
+<p>The cam-shafts shown at <a href="#Fig133">Figs. 133</a> and <a href="#Fig134">134</a>, B, are of
+the latter type, as the cams are machined integrally. In
+this case not only the cams but also the gears used in
+driving the auxiliary shafts are forged integral. This is
+a more expensive construction, because of the high initial
+cost of forging dies as well as the greater expense of
+machining. It has the advantage over the other form in
+which the cams are keyed in place in that it is stronger,
+and as the cams are a part of the shaft they can never
+become loose, as might be possible where they are separately
+formed and assembled on a simple shaft.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig134" id="Fig134"></a>
+<img src="images/illo309.png" alt="Fig. 134" width="450" height="474" />
+<p class="caption">Fig. 134.&mdash;Important Parts of Duesenberg Aviation Engine. A&mdash;Three
+Main Bearing Crank-Shaft. B&mdash;Cam-Shaft with Integral Cams. C&mdash;Piston
+and Connecting Rod Assembly. D&mdash;Valve Rocker Group.
+E&mdash;Piston. F&mdash;Main Bearing Brasses.</p></div>
+
+<p>The importance of the crank-shaft has been previously<span class='pagenum'><a name="Page_314" id="Page_314">[314]</a></span>
+considered, and some of its forms have been shown in
+views of the motors presented in earlier portions of this
+work. The crank-shaft is one of the parts subjected to
+the greatest strain and extreme care is needed in its construction
+and design, because practically the entire duty
+of transmitting the power generated by the motor to the
+gearset devolves upon it. Crank-shafts are usually made
+of high tensile strength steel of special composition. They
+may be made in four ways, the most common being from<span class='pagenum'><a name="Page_315" id="Page_315">[315]</a></span>
+a drop or machine forging which is formed approximately
+to the shape of the finished shaft and in rare instances
+(experimental motors only) they may be steel castings.
+Sometimes they are made from machine forgings, where
+considerably more machine work is necessary than would
+be the case where the shaft is formed between dies.
+Some engineers favor blocking the shaft out of a solid
+slab of metal and then machining this rough blank to
+form. In some radial-cylinder motors of the Gnome and
+Le Rhone type the crank-shafts are built up of two pieces,
+held together by taper fastenings or bolts.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig135" id="Fig135"></a>
+<img src="images/illo310.png" alt="Fig. 135" width="600" height="232" />
+<p class="caption">Fig. 135.&mdash;Showing Method of Making Crank-Shaft. A&mdash;The Rough Steel
+Forging Before Machining. B&mdash;The Finished Six-Throw, Seven-Bearing
+Crank-Shaft.</p></div>
+
+<p>The form of the shaft depends on the number of
+cylinders and the form has material influence on the
+method of construction. For instance, a four-cylinder
+crank-shaft could be made by either of the methods outlined.
+On the other hand, a three- or six-cylinder shaft
+is best made by the machine forging process, because if
+drop forged or cut from the blank it will have to be
+heated and the crank throws bent around so that the pins
+will lie in three planes one hundred and twenty degrees
+apart, while the other types described need no further
+attention, as the crank-pins lie in planes one hundred
+and eighty degrees apart. This can be better understood
+by referring to <a href="#Fig135">Fig. 135</a>, which shows a six-cylinder shaft
+in the rough and finished stages. At A the appearance<span class='pagenum'><a name="Page_316" id="Page_316">[316]</a></span>
+of the machine forging before any of the material is removed
+is shown, while at B the appearance of the finished
+crank-shaft is clearly depicted. The built-up crank-shaft
+is seldom used on multiple-cylinder motors, except in
+some cases where the crank-shafts revolve on ball bearings
+as in some automobile racing engines.</p>
+
+<div class="figcenter" style="width: 550px;"><a name="Fig136" id="Fig136"></a>
+<img src="images/illo311a.png" alt="Fig. 136" width="550" height="222" />
+<p class="caption">Fig. 136.&mdash;Showing Form of Crank-Shaft for Twin-Cylinder Opposed
+Power Plant.</p></div>
+
+<div class="figcenter" style="width: 550px;"><a name="Fig137" id="Fig137"></a>
+<img src="images/illo311b.jpg" alt="Fig. 137" width="550" height="207" />
+<p class="caption">Fig. 137.&mdash;Crank-Shaft of Thomas-Morse Eight-Cylinder Vee Engine.</p></div>
+
+<p>Crank-shaft form will vary with a number of cylinders
+and it is possible to use a number of different arrangements
+of crank-pins and bearings for the same number
+of cylinders. The simplest form of crank-shaft is that
+used on simple radial cylinder motors as it would consist
+of but one crank-pin, two webs, and the crank-shaft. As
+the number of cylinders increase in Vee motors as a general
+rule more crank-pins are used. The crank-shaft that<span class='pagenum'><a name="Page_317" id="Page_317">[317]</a></span>
+would be used on a two-cylinder opposed motor is shown
+at <a href="#Fig136">Fig. 136</a>. This has two throws and the crank-pins are
+spaced 180 degrees apart. The bearings are exceptionally
+long. Four-cylinder crank-shafts may have two,
+three or five main bearings and three or four crank-pins.
+In some forms of two-bearing crank-shafts, such as used
+when four-cylinders are cast in a block, or unit casting,
+two of the pistons are attached to one common crank-pin,
+so that in reality the crank-shaft has but three crank-pins.
+A typical three bearing, four-cylinder crank-shaft
+is shown at <a href="#Fig134">Fig. 134</a>, A. The same type can be used for
+an eight-cylinder Vee engine, except for the greater length
+of crank-pins to permit of side by side rods as shown at
+<a href="#Fig137">Fig. 137</a>. Six cylinder vertical tandem and twelve-cylinder
+Vee engine crank-shafts usually have four or seven
+main bearings depending upon the disposition of the
+crank-pins and arrangement of cylinders. At <a href="#Fig138">Fig. 138</a>,
+A,<span class='pagenum'><a name="Page_318" id="Page_318">[318]</a></span>
+the bottom view of a twelve-cylinder engine with bottom
+half of crank case removed is given. This illustrates
+clearly the arrangement of main bearings when the crank-shaft
+is supported on four journals. The crank-shaft
+shown at <a href="#Fig138">Fig. 138</a>, B, is a twelve-cylinder seven-bearing
+type.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig138" id="Fig138"></a>
+<img src="images/illo312.png" alt="Fig. 138" width="500" height="386" />
+<p class="caption">Fig. 138.&mdash;Crank-Case and Crank-Shaft Construction for Twelve-Cylinder
+Motors. A&mdash;Duesenberg. B&mdash;Curtiss.</p></div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig139" id="Fig139"></a>
+<img src="images/illo313.png" alt="Fig. 139" width="500" height="375" />
+<p class="caption">Fig. 139.&mdash;Counterbalanced Crank-Shafts Reduce Engine Vibration and
+Permit of Higher Rotative Speeds.</p></div>
+
+<p>In some automobile engines, extremely good results
+have been secured in obtaining steady running with minimum
+vibration by counterbalancing the crank-shafts as
+outlined at <a href="#Fig139">Fig. 139</a>. The shaft at A is a type suitable
+for a high speed four-cylinder vertical or an eight-cylinder
+Vee type. That at B is for a six-cylinder vertical or
+a twelve-cylinder V with scissors joint rods. If counterbalancing
+crank-shafts helps in an automobile engine, it
+should have advantages of some moment in airplane engines,
+even though the crank-shaft weight is greater.</p>
+
+<p class='pagenum'><a name="Page_319" id="Page_319">[319]</a></p>
+
+<h3><a name="SecIX_9" id="SecIX_9"></a>BALL-BEARING CRANK-SHAFTS</h3>
+
+<p>While crank-shafts are usually supported in plain
+journals there seems to be a growing tendency of late
+to use anti-friction bearings of the ball type for their
+support. This is especially noticeable on block motors
+where but two main bearings are utilized. When ball
+bearings are selected with proper relation to the load
+which obtains they will give very satisfactory service.
+They permit the crank-shaft to turn with minimum friction,
+and if properly selected will never need adjustment.
+The front end is supported by a bearing which is clamped
+in such a manner that it will take a certain amount of
+load in a direction parallel to the axis of the shaft, while
+the rear end is so supported that the outer race of the
+bearing has a certain amount of axial freedom or &#8220;float.&#8221;
+The inner race or cone of each bearing is firmly clamped
+against shoulders on the crank-shaft. At the front end
+of the crank-shaft timing gear and a suitable check nut
+are used, while at the back end the bearing is clamped
+by a threaded retention member between the fly-wheel
+and a shoulder on the crank-shaft. The fly-wheel is held
+in place by a taper and key retention. The ball bearings
+are carried in a light housing of bronze or malleable iron,
+which in turn are held in the crank-case by bolts. The
+Renault engine uses ball bearings at front and rear ends
+of the crank-shaft, but has plain bearings around intermediate
+crank-shaft journals. The rotary engines of the
+Gnome, Le Rhone and Clerget forms would not be practical
+if ball bearings were not used as the bearing friction
+and consequent depreciation would be very high.</p>
+
+<h3><a name="SecIX_10" id="SecIX_10"></a>ENGINE-BASE CONSTRUCTION</h3>
+
+<p>One of the important parts of the power plant is the
+substantial casing or bed member, which is employed to
+support the cylinders and crank-shaft and which is attached
+directly to the fuselage engine supporting members.<span class='pagenum'><a name="Page_320" id="Page_320">[320]</a></span>
+This will vary widely in form, but as a general
+thing it is an approximately cylindrical member which
+may be divided either vertically or horizontally in two
+or more parts. Airplane engine crank-cases are usually
+made of aluminum, a material which has about the same
+strength as cast iron, but which only weighs a third as
+much. In rare cases cast iron is employed, but is not
+favored by most engineers because of its brittle nature,
+great weight and low resistance to tensile stresses. Where
+exceptional strength is needed alloys of bronze may be
+used, and in some cases where engines are produced in
+large quantities a portion of the crank-case may be a
+sheet steel or aluminum stamping.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig140" id="Fig140"></a>
+<img src="images/illo315.jpg" alt="Fig. 140" width="500" height="349" />
+<p class="caption">Fig. 140.&mdash;View of Thomas 135 Horse-Power Aeromotor, Model 8, Showing
+Conventional Method of Crank-Case Construction.</p></div>
+
+<p>Crank-cases are always large enough to permit the
+crank-shaft and parts attached to it to turn inside and
+obviously its length is determined by the number of cylinders
+and their disposition. The crank-case of the radial
+cylinder or double-opposed cylinder engine would be substantially
+the same in length. That of a four-cylinder<span class='pagenum'><a name="Page_321" id="Page_321">[321]</a></span>
+will vary in length with the method of casting the cylinder.
+When the four-cylinders are cast in one unit and
+a two-bearing crank-shaft is used, the crank-case is a very
+compact and short member. When a three-bearing crank-shaft
+is utilized and the cylinders are cast in pairs, the
+engine base is longer than it would be to support a block
+casting, but is shorter than one designed to sustain individual<span class='pagenum'><a name="Page_322" id="Page_322">[322]</a></span>
+cylinder castings and a five-bearing crank-shaft.
+It is now common construction to cast an oil container
+integral with the bottom of the engine base and to draw
+the lubricating oil from it by means of a pump, as shown
+at <a href="#Fig140">Fig. 140</a>. The arms by which the motor is
+supported<span class='pagenum'><a name="Page_323" id="Page_323">[323]</a></span>
+in the fuselage are substantial-ribbed members cast integrally
+with the upper half.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig141" id="Fig141"></a>
+<img src="images/illo316.jpg" alt="Fig. 141" width="450" height="585" />
+<p class="caption">Fig. 141.&mdash;Views of Upper Half of Thomas Aeromotor Crank-Case.</p></div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig142" id="Fig142"></a>
+<img src="images/illo317.png" alt="Fig. 142" width="400" height="541" />
+<p class="caption">Fig. 142.&mdash;Method of Constructing Eight-Cylinder Vee Engine, Possible
+if Aluminum Cylinder and Crank-Case Castings are Used.</p></div>
+
+<p>The approved method of crank-case construction favored
+by the majority of engineers is shown at the top of
+<a href="#Fig141">Fig. 141</a>, bottom side up. The upper half not only forms
+a bed for the cylinder but is used to hold the crank-shaft
+as well. In the illustration, the three-bearing boxes form
+part of the case, while the lower brasses are in the form
+of separately cast caps retained by suitable bolts. In
+the construction outlined the bottom part of the case
+serves merely as an oil container and a protection for
+the interior mechanism of the motor. The cylinders are
+held down by means of studs screwed into the crank-case
+top, as shown at <a href="#Fig141">Fig. 141</a>, lower view. If the aluminum
+cylinder motor has any future, the method of construction
+outlined at <a href="#Fig142">Fig. 142</a>, which has been used in cast iron
+for an automobile motor, might be used for an eight-cylinder
+Vee engine for airplane use. The simplicity of
+the crank-case needed for a revolving cylinder motor
+and its small weight can be well understood by examination
+of the illustration at <a href="#Fig143">Fig. 143</a>, which shows the engine
+crank-case for the nine-cylinder &#8220;Monosoupape&#8221;
+Gnome engine. This consists of two accurately machined
+forgings held together by bolts as clearly indicated.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig143" id="Fig143"></a>
+<img src="images/illo318.jpg" alt="Fig. 143" width="500" height="251" />
+<p class="caption">Fig. 143.&mdash;Simple and Compact Crank-Case, Possible When Radial Cylinder
+Engine Design is Followed.</p></div>
+
+<hr class="c25" />
+<p class='pagenum'><a name="Page_324" id="Page_324">[324]</a></p>
+<h2><a name="ChX" id="ChX"></a>CHAPTER X</h2>
+
+<div class="chapsec"><p><a href="#SecX_1">Power Plant Installation</a>&mdash;<a href="#SecX_2">Curtiss OX-2 Engine Mounting and Operating
+Rules</a>&mdash;<a href="#SecX_3">Standard S. A. E. Engine Bed Dimensions</a>&mdash;<a href="#SecX_4">Hall-Scott Engine Installation and
+Operation</a>&mdash;<a href="#SecX_5">Fuel System Rules</a>&mdash;<a href="#SecX_6">Ignition System</a>&mdash;<a href="#SecX_7">Water
+System</a>&mdash;<a href="#SecX_8">Preparations to Start Engine</a>&mdash;<a href="#SecX_9">Mounting Radial and Rotary Engines</a>&mdash;<a
+href="#SecX_10">Practical Hints to Locate Engine Troubles</a>&mdash;<a href="#SecX_11">All Engine Troubles Summarized</a>&mdash;<a
+href="#SecX_12">Location of Engine Troubles Made Easy</a>.</p></div>
+
+<p><a name="SecX_1" id="SecX_1"></a>The proper installation of the airplane power plant
+is more important than is generally supposed, as while
+these engines are usually well balanced and run with little
+vibration, it is necessary that they be securely anchored
+and that various connections to the auxiliary parts be
+carefully made in order to prevent breakage from vibration
+and that attendant risk of motor stoppage while in
+the air. The type of motor to be installed determines
+the method of installation to be followed. As a general
+rule six-cylinder vertical engine and eight-cylinder Vee
+type are mounted in substantially the same way. The
+radial, fixed cylinder forms and the radial, rotary cylinder
+Gnome and Le Rhone rotary types require an entirely
+different method of mounting. Some unconventional
+mountings have been devised, notably that shown at <a href="#Fig144">Fig.
+144</a>, which is a six-cylinder German engine that is installed
+in just the opposite way to that commonly followed.
+The inverted cylinder construction is not generally
+followed because even with pressure feed, dry
+crank-case type lubricating system there is considerable
+danger of over-lubrication and of oil collecting and carbonizing
+in the combustion chamber and gumming up
+the valve action much quicker than would be the case if
+the engine was operated in the conventional upright position.
+The reason for mounting an engine in this way is
+to obtain a lower center of gravity and also to make for<span class='pagenum'><a name="Page_325" id="Page_325">[325]</a></span>
+more perfect streamlining of the front end of the fuselage
+in some cases. It is rather doubtful if this slight advantage
+will compensate for the disadvantages introduced
+by this unusual construction. It is not used to
+any extent now but is presented merely to show one of
+the possible systems of installing an airplane engine.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig144" id="Fig144"></a>
+<img src="images/illo320.png" alt="Fig. 144" width="450" height="369" />
+<p class="caption">Fig. 144.&mdash;Unconventional Mounting of German Inverted Cylinder Motor.</p></div>
+
+<div class="figcenter" style="width: 550px;"><a name="Fig145" id="Fig145"></a>
+<img src="images/illo321.jpg" alt="Fig. 145" width="550" height="390" />
+<p class="caption">Fig. 145.&mdash;How Curtiss Model OX-2 Motor is Installed in Fuselage of
+Curtiss Tractor Biplane. Note Similarity of Mounting to Automobile
+Power Plant.</p></div>
+
+<p>In a number of airplanes of the tractor-biplane type
+the power plant installation is not very much different
+than that which is found in automobile practice. The
+illustration at <a href="#Fig145">Fig. 145</a> is a very clear representation of
+the method of mounting the Curtiss eight-cylinder 90
+H. P. or model OX-2 engine in the fuselage of the Curtiss
+JN-4 tractor biplane which is so generally used in the
+United States as a training machine. It will be observed
+that the fuel tank is mounted under a cowl directly behind
+the motor and that it feeds the carburetor by means of a<span class='pagenum'><a name="Page_326" id="Page_326">[326]</a></span>
+flexible fuel pipe. As the tank is mounted higher than the
+carburetor, it will feed that member by gravity. The
+radiator is mounted at the front end of the fuselage and
+connected to the water piping on the motor by the usual
+rubber hose connections. An oil pan is placed under the
+engine and the top is covered with a hood just as in
+motor car practice. The panels of aluminum are attached
+to the sides of the fuselage and are supplied with doors
+which open and provide access to the carburetor, oil-gauge
+and other parts of the motor requiring inspection.
+The complete installation with the power plant enclosed
+is given at <a href="#Fig146">Fig. 146</a>, and in this it will be observed that
+the exhaust pipes are connected to discharge members
+that lead the gases above the top plane. In the engine
+shown at <a href="#Fig145">Fig. 145</a> the exhaust flows directly into the air
+at the sides of the machine through short pipes bolted to
+the exhaust gas outlet ports. The installation of the<span
+class='pagenum'><a name="Page_328" id="Page_328">[328]</a></span><span class='pagenum'><a name="Page_327" id="Page_327"></a></span>
+radiator just back of the tractor screw insures that adequate
+cooling will be obtained because of the rapid air
+flow due to the propeller slip stream.</p>
+
+<div class="figcenter" style="width: 550px;"><a name="Fig146" id="Fig146"></a>
+<img src="images/illo322.jpg" alt="Fig. 146" width="550" height="323" />
+<p class="caption">Fig. 146.&mdash;Latest Model of Curtiss JN-4 Training Machine, Showing Thorough Enclosure of Power Plant and
+Method of Disposing of the Exhaust Gases.</p></div>
+
+<div class="figcenter" style="width: 550px;"><a name="Fig147" id="Fig147"></a>
+<img src="images/illo323.png" alt="Fig. 147" width="550" height="437" />
+<p class="caption">Fig. 147.&mdash;Front View of L. W. F. Tractor Biplane Fuselage, Showing
+Method of Installing Thomas Aeromotor and Method of Disposing of
+Exhaust Gases.</p></div>
+
+<h3><a name="SecX_2" id="SecX_2"></a>INSTALLATION OF CURTISS OX-2 ENGINE</h3>
+
+<p>The following instructions are given in the Curtiss
+Instruction Book for installing the OX-2 engine and preparing
+it for flights, and taken in connection with the very
+clear illustration presented no difficulty should be experienced
+in understanding the proper installation, and mounting
+of this power plant. The bearers or beds should be
+2 inches wide by 3 inches deep, preferably of laminated
+hard wood, and placed 11<sup>5</sup>&#8260;<sub>8</sub> inches apart. They must be
+well braced. The six arms of the base of the motor are<span class='pagenum'><a name="Page_329" id="Page_329">[329]</a></span>
+drilled for <sup>3</sup>&#8260;<sub>8</sub>-inch bolts, and none but this size should
+he used.</p>
+
+<p>1. <i>Anchoring the Motor.</i> Put the bolts in from the
+bottom, with a large washer under the head of each so
+the head cannot cut into the wood. On every bolt use a
+castellated nut and a cotter pin, or an ordinary nut and
+a lock washer, so the bolt will not work loose. Always
+set motor in place and fasten before attaching any auxiliary
+apparatus, such as carburetor, etc.</p>
+
+<p>2. <i>Inspecting the Ignition-Switch Wires.</i> The wires
+leading from the ignition switch must be properly connected&mdash;one
+end to the motor body for ground, and the
+other end to the post on the breaker box of the magneto.</p>
+
+<p>3. <i>Filling the Radiator.</i> Be sure that the water from
+the radiator fills the cylinder jackets. Pockets of air
+may remain in the cylinder jackets even though the
+radiator may appear full. Turn the motor over a few
+times by hand after filling the radiator, and then add
+more water if the radiator will take it. The air pockets,
+if allowed to remain, may cause overheating and develop
+serious trouble when the motor is running.</p>
+
+<p>4. <i>Filling the Oil Reservoir.</i> Oil is admitted into the
+crank-case through the breather tube at the rear. It is
+well to strain all oil put into the crank-case. In filling the
+oil reservoir be sure to turn the handle on the oil sight-gauge
+till it is at right angles with the gauge. The oil
+sight-gauge is on the side of the lower half of the crank-case.
+Put in about 3 gallons of the best obtainable oil,
+Mobile B recommended. It is important to remember
+that the very best oil is none too good.</p>
+
+<p>5. <i>Oiling Exposed Moving Parts.</i> Oil all rocker-arm
+bearings before each flight. A little oil should be applied
+where the push rods pass through the stirrup straps.</p>
+
+<p>6. <i>Filling the Gasoline Tanks.</i> Be certain that all
+connections in the gasoline system are tight.</p>
+
+<p>7. <i>Turning on the Gasoline.</i> Open the cock leading
+from the gasoline tank to the carburetor.</p>
+
+<p>8. <i>Charging the Cylinders.</i> With the ignition switch<span class='pagenum'><a name="Page_330" id="Page_330">[330]</a></span>
+OFF, prime the motor by squirting a little gasoline in
+each exhaust port and then turn the propeller backward
+two revolutions. Never open the exhaust valve by operating
+the rocker-arm by hand, as the push-rod is liable to
+come out of its socket in the cam follower and bend the
+rocker-arm when the motor turns over.</p>
+
+<p>9. <i>Starting the Motor by Hand.</i> Always retard the
+spark part way, to prevent back-firing, by pulling forward
+the wire attached to the breaker box. Failure to so
+retard the spark in starting may result in serious injury
+to the operator. Turn on the ignition switch with throttle
+partly open; give a quick, strong pull down and outward
+on the starting crank or propeller. As soon as the motor
+is started advance the spark by releasing the retard wire.</p>
+
+<p>10. <i>Oil Circulation.</i> Let the motor run at low speed
+for a few minutes in order to establish oil circulation in
+all bearings. With all parts functioning properly, the
+throttle may be opened gradually for warming up before
+flight.</p>
+
+<h3><a name="SecX_3" id="SecX_3"></a>STANDARD S.A.E. ENGINE BED DIMENSIONS</h3>
+
+<p>The Society of Automotive Engineers have made efforts
+to standardize dimensions of bed timbers for supporting
+power plant in an aeroplane. Owing to the great
+difference in length no standardization is thought possible
+in this regard. The dimensions recommended are as
+follows:</p>
+
+<table class="fsize80" summary="Table p 330">
+
+<tr>
+<td class="left padr5">Distance between timbers</td>
+<td class="right padr0">12</td>
+<td>&nbsp;</td>
+<td class="left padl1 padr5">in.</td>
+<td class="right padr0">14</td>
+<td>&nbsp;</td>
+<td class="left padl1 padr5">in.</td>
+<td class="right padl1">16</td>
+<td class="left padl1">in.</td>
+</tr>
+
+<tr>
+<td class="left padr5">Width of bed timbers</td>
+<td class="right padr0">1</td>
+<td class="left padl0"><sup>1</sup>&#8260;<sub>2</sub></td>
+<td class="left padl1 padr5">in.</td>
+<td class="right padr0">1</td>
+<td class="left padl0 padr1"><sup>3</sup>&#8260;<sub>4</sub></td>
+<td class="left padl1 padr5">in.</td>
+<td class="right padl1">2</td>
+<td class="left padl1">in.</td>
+</tr>
+
+<tr>
+<td class="left padr5">Distance between centers of bolts</td>
+<td class="right padr0">13</td>
+<td class="left padl0"><sup>1</sup>&#8260;<sub>2</sub></td>
+<td class="left padl1 padr5">in.</td>
+<td class="right padr0">15</td>
+<td class="left padl0 padr1"><sup>3</sup>&#8260;<sub>4</sub></td>
+<td class="left padl1 padr5">in.</td>
+<td class="right padl1">18</td>
+<td class="left padl1">in.</td>
+</tr>
+
+</table>
+
+<p>It will be evident that if any standard of this nature
+were adopted by engine builders that the designers of
+fuselage could easily arrange their bed timbers to conform
+to these dimensions, whereas it would be difficult to
+have them adhere to any standard longitudinal dimensions
+which are much more easily varied in fuselages
+than the transverse dimensions are. It, however, should<span
+class='pagenum'><a name="Page_332" id="Page_332">[332]</a></span><span class='pagenum'><a name="Page_331" id="Page_331"></a></span>
+be possible to standardize the longitudinal positions of
+the holding down bolts as the engine designer would still
+be able to allow himself considerable space fore-and-aft
+of the bolts.</p>
+
+<h3><a name="SecX_4" id="SecX_4"></a>HALL-SCOTT ENGINE INSTALLATION</h3>
+
+<div class="figcenter" style="width: 550px;"><a name="Fig148" id="Fig148"></a>
+<p class="leftlink"><a href="images/large326.png">Large<br />image<br />(60 kB).</a></p>
+<img src="images/illo326.png" alt="Fig. 148" width="550" height="350" />
+<p class="caption">Fig. 148.&mdash;End Elevation of Hall-Scott A-7 Four-Cylinder Motor, with Installation Dimensions.</p></div>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig149" id="Fig149"></a>
+<p class="leftlink"><a href="images/large327.png">Large<br />image<br />(113 kB).</a></p>
+<img src="images/illo327.png" alt="Fig. 149" width="450" height="497" />
+<p class="caption">Fig. 149.&mdash;Plan and Side Elevation of Hall-Scott A-7 Four-Cylinder Airplane
+Engine, with Installation Dimensions.</p></div>
+
+<p>The very thorough manner in which installation diagrams
+are prepared by the leading engine makers leaves
+nothing to the imagination. The dimensions of the Hall-Scott
+four-cylinder airplane engine are given clearly in<span class='pagenum'><a name="Page_333" id="Page_333">[333]</a></span>
+our inch measurements with the metric equivalents at
+<a href="#Fig148">Figs. 148</a> and <a href="#Fig149">149</a>, the former showing a vertical elevation
+while the latter has a plan view and side elevation.
+The installation of this engine in airplanes is clearly
+shown at <a href="#Fig150">Figs. 150</a> and <a href="#Fig151">151</a>, the former having the radiator
+installed at the front of the motor and having all
+exhaust pipes joined to one common discharge funnel,
+which deflects the gas over the top plane while the latter
+has the radiator placed vertically above the motor at
+the back end and has a direct exhaust gas discharge to
+the air.</p>
+
+<p class="center" style="margin-top: 2em;"><a name="Fig150" id="Fig150"></a>Fig. 150.</p>
+
+<p class="center fsize200 gesp">CENSORED</p>
+
+<p class="center" style="margin-top: 2em;"><a name="Fig151" id="Fig151"></a>Fig. 151.</p>
+
+<p class="center fsize200 gesp">CENSORED</p>
+
+<p>The dimensions of the six-cylinder Hall-Scott motor
+which is known as the type A-5 125 H. P. are given at
+<a href="#Fig152">Fig. 152</a>, which is an end sectional elevation, and at <a href="#Fig153">Fig.
+153</a>, which is a plan view. The dimensions are given both
+in inch sizes and the metric equivalents. The appearance<span class='pagenum'><a name="Page_334" id="Page_334">[334]</a></span>
+of a Hall-Scott six-cylinder engine installed in a fuselage
+is given at <a href="#Fig154">Fig. 154</a>, while a diagram showing the location
+of the engine and the various pipes leading to the
+auxiliary groups is outlined at <a href="#Fig155">Fig. 155</a>. The following
+instructions for installing the Hall-Scott power plant are<span class='pagenum'><a name="Page_336"
+id="Page_336">[336]</a></span><span class='pagenum'><a name="Page_335" id="Page_335"></a></span>
+reproduced from the instruction book issued by the maker.
+Operating instructions which are given should enable any
+good mechanic to make a proper installation and to keep
+the engine in good running condition.</p>
+
+<p class="center" style="margin-top: 2em;"><a name="Fig152" id="Fig152"></a>Fig. 152.</p>
+
+<p class="center fsize200 gesp">CENSORED</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig153" id="Fig153"></a>
+<p class="leftlink"><a href="images/large331.png">Large<br />image<br />(67 kB).</a></p>
+<img src="images/illo331.png" alt="Fig. 153" width="600" height="307" />
+<p class="caption">Fig. 153.&mdash;Plan View of Hall-Scott Type A-5 125 Horse-Power Airplane
+Engine, Showing Installation Dimensions.</p></div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig154" id="Fig154"></a>
+<img src="images/illo332.jpg" alt="Fig. 154" width="400" height="562" />
+<p class="caption">Fig. 154.&mdash;Three-Quarter View of Hall-Scott Type A-5 125 Horse-Power
+Six-Cylinder Engine, with One of the Side Radiators Removed to
+Show Installation in Standard Fuselage.</p></div>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig155" id="Fig155"></a>
+<img src="images/illo333.png" alt="Fig. 155" width="600" height="351" />
+<p class="caption">Fig. 155.&mdash;Diagram Showing Proper Installation of Hall-Scott Type A-5 125 Horse-Power Engine with Pressure
+Feed Fuel Supply System.</p></div>
+
+<h3><a name="SecX_5" id="SecX_5"></a>FUEL SYSTEM INSTALLATION</h3>
+
+<p>Gasoline giving the best results with this equipment
+is as follows: Gravity 58-62 deg. Baume A. Initial boiling
+point&mdash;Richmond method&mdash;<span class="nowrap">102&deg;</span> Fahr. Sulphur .014.
+Calorimetric bomb test 20610 B. T. U. per pound. If the
+gasoline tank is placed in the fuselage below the level of
+the carburetor, a hand pump must be used to maintain
+air pressure in gas tank to force the gasoline to the carburetor.
+After starting the engine the small auxiliary air
+pump upon the engine will maintain sufficient pressure.
+A-7a and A-5a engines are furnished with a new type
+auxiliary air pump. This should be frequently oiled and
+care taken so no grit or sand will enter which might lodge
+between the valve and its seat, which would make it fail
+to operate properly. An air relief valve is furnished with
+each engine. It should be screwed into the gas tank and
+properly regulated to maintain the pressure required.<span class='pagenum'><a name="Page_337" id="Page_337">[337]</a></span>
+This is done by screwing the ratchet on top either up or
+down. If two tanks are used in a plane one should be
+installed in each tank. All air pump lines should be carefully<span class='pagenum'><a name="Page_339"
+id="Page_339">[339]</a></span><span class='pagenum'><a name="Page_338" id="Page_338"></a></span>
+gone over quite frequently to ascertain if they are
+tight. Check valves have to be placed in these lines. In
+some cases the gasoline tank is placed above the engine,
+allowing it to drain by gravity to the carburetor. When
+using this system there should be a drop of not less than
+two feet from the lowest portion of the gasoline tank to
+the upper part of the carburetor float chamber. Even
+this height might not be sufficient to maintain the proper
+volume of gasoline to the carburetor at high speeds. Air
+pressure is advised upon all tanks to insure the proper
+supply of gasoline. When using gravity feed without
+air pressure be sure to vent the tank to allow circulation
+of air. If gravity tank is used and the engine runs satisfactorily
+at low speeds but cuts out at high speeds the
+trouble is undoubtedly due to insufficient height of the
+tank above the carburetor. The tank should be raised or
+air pressure system used.</p>
+
+<h3><a name="SecX_6" id="SecX_6"></a>IGNITION SWITCHES</h3>
+
+<p>Two &#8220;DIXIE&#8221; switches are furnished with each engine.
+Both of these should be installed in the pilot&#8217;s
+seat, one controlling the R. H., and the other the L. H.
+magneto. By shorting either one or the other it can be
+quickly determined if both magnetos, with their respective
+spark-plugs, are working correctly. Care should be
+taken not to use spark-plugs having <i>special extensions or
+long protruding points</i>. Plugs giving best results are extremely
+small with short points.</p>
+
+<h3><a name="SecX_7" id="SecX_7"></a>WATER SYSTEMS</h3>
+
+<p>A temperature gauge should be installed in the water
+pipe, coming directly from the cylinder nearest the propeller
+(note illustration above). This instrument installed
+in the radiator cap has not always given satisfactory
+results. This is especially noticeable when the
+water in the radiator becomes low, not allowing it to
+touch the bulb on the moto-meter. For ordinary running,<span class='pagenum'><a name="Page_340" id="Page_340">[340]</a></span>
+it should not indicate over 150 degrees Fahr. In climbing
+tests, however, a temperature of 160 degrees Fahr.
+can be maintained without any ill effects upon the engine.
+In case the engine becomes overheated, the indicator
+will register above 180 degrees Fahr., in which case
+it should be stopped immediately. Overheating is most
+generally caused by retarded spark, excessive carbon in
+the cylinders, insufficient lubrication, improperly timed
+valves, lack of water, clogging of water system in any
+way which would obstruct the free circulation of the
+water.</p>
+
+<p>Overheating will cause the engine to knock, with possible
+damaging results. Suction pipes should be made
+out of thin tubing, and run within a quarter or an eighth
+of an inch of each other, so that when a hose is placed
+over the two, it will not be possible to suck together.
+This is often the case when a long rubber hose is used,
+which causes overheating. Radiators should be flushed
+out and cleaned thoroughly quite often. A dirty radiator
+may cause overheating.</p>
+
+<p>When filling the radiator it is very important to remove
+the plug on top of the water pump until water
+appears. This is to avoid air pockets being formed in the
+circulating system, which might not only heat up the
+engine, but cause considerable damage. All water pump
+hoses and connections should be tightly taped and shellacked
+after the engine is properly installed in the plane.
+The greatest care should be taken when making engine
+installation <i>not</i> to use smaller inside diameter hose connection
+than water pump suction end casting. One inch
+and a quarter inside diameter should be used on A-7 and
+A-5 motors, while nothing less than one inch and a half
+inside diameter hose or tubing on all A-7a and A-5a engines.
+It is further important to have light spun tubing,
+void of any sharp turns, leads from pump to radiator and
+cylinder water outlet to radiator. In other words, the
+water circulation through the engine must be as little
+restricted as possible. Be sure no light hose is used, that<span class='pagenum'><a name="Page_341" id="Page_341">[341]</a></span>
+will often suck together when engine is started. To thoroughly
+drain the water from the entire system, open the
+drain cock at the lowest side of the water pump.</p>
+
+<h3><a name="SecX_8" id="SecX_8"></a>PREPARATIONS TO START ENGINE</h3>
+
+<p>Always replenish gasoline tanks through a strainer
+which is clean. This strainer must catch all water and
+other impurities in the gasoline. Pour at least three
+gallons of fresh oil into the lower crank-case. Oil all
+rocker arms through oilers upon rocker arm housing caps.
+Be sure radiators are filled within one inch of the top.</p>
+
+<p>After all the parts are oiled, and the tanks filled, the
+following must be looked after before starting: See if
+crank-shaft flange is tight on shaft. See if propeller bolts
+are tight and evenly drawn up. See if propeller bolts are
+wired. See if propeller is trued up to within <span class="nowrap"><sup>1</sup>&#8260;<sub>8</sub>&#8242;&#8242;.</span></p>
+
+<p>Every four days the magnetos should be oiled if the
+engine is in daily use.</p>
+
+<p>Every month all cylinder hold-down nuts should be
+gone over to ascertain if they are tight. (Be sure to recotter
+nuts.)</p>
+
+<p>See if magnetos are bolted on tight and wired.</p>
+
+<p>See if magneto cables are in good condition.</p>
+
+<p>See if rocker arm tappets have a <span class="nowrap">.020&#8242;&#8242;</span> clearance from
+valve stem when valve is seated.</p>
+
+<p>See if tappet clamp screws are tight and cottered.</p>
+
+<p>See if all gasoline, oil, water pipes and connections are
+in perfect condition.</p>
+
+<p>Air on gas line should be tested for leaks.</p>
+
+<p>Pump at least three pounds air pressure into gasoline
+tank.</p>
+
+<p>After making sure that above rules have been observed,
+test compression of cylinders by turning propeller.</p>
+
+<p class="center">&#8220;DO NOT FORGET TO SHORT BOTH MAGNETOS&#8221;</p>
+
+<p>Be sure all compression release and priming cocks do
+not leak compression. If they do, replace same with a<span class='pagenum'><a name="Page_342" id="Page_342">[342]</a></span>
+new one immediately, as this might cause premature
+firing.</p>
+
+<p>Open priming cocks and squirt some gasoline into each.</p>
+
+<p>Close cocks.</p>
+
+<p>Open compression release cocks.</p>
+
+<p>Open throttle slightly.</p>
+
+<p>If using Berling magnetos they should be three-quarters
+advanced.</p>
+
+<p>If all the foregoing directions have been carefully
+followed, the engine is ready for starting.</p>
+
+<p>In cranking engine either by starting crank, or propeller,
+it is essential to throw it over compression quickly.</p>
+
+<p>Immediately upon starting, close compression release
+cocks.</p>
+
+<p>When engine is running, advance magnetos.</p>
+
+<p>After it has warmed up, short one magneto and then
+the other, to be sure both magnetos and spark-plugs are
+firing properly. If there is a miss, the fouled plug must
+be located and cleaned. There is a possibility that the
+jets in the carburetor are stopped up. If this is the case,
+do not attempt to clean same with any sharp instrument.
+If this is done, it might change the opening in the jets,
+thus spoiling the adjustment. Jets and nozzles should
+be blown out with air or steam.</p>
+
+<p>An open intake or exhaust valve, which might have
+become sluggish or stuck from carbon, might cause
+trouble. Be sure to remedy this at once by using a little
+coal-oil or kerosene on same, working the valve by hand
+until it becomes free. We recommend using graphite on
+valve stems mixed with oil to guard against sticking or
+undue wear.</p>
+
+<h3><a name="SecX_9" id="SecX_9"></a>INSTALLING ROTARY AND RADIAL CYLINDER ENGINES</h3>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig156" id="Fig156"></a>
+<img src="images/illo338.png" alt="Fig. 156" width="600" height="350" />
+<p class="caption">Fig. 156.&mdash;Diagram Defining Installation of Gnome &#8220;Monosoupape&#8221;
+Motor in Tractor Biplane. Note Necessary
+Piping for Fuel, Oil, and Air Lines.</p></div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig157" id="Fig157"></a>
+<img src="images/illo339.png" alt="Fig. 157" width="500" height="322" />
+<p class="caption">Fig. 157.&mdash;Showing Two Methods of Placing Propeller on Gnome Rotary
+Motor.</p></div>
+
+<p>When rotary engines are installed simple steel stamping
+or &#8220;spiders,&#8221; are attached to the fuselage to hold the
+fixed crank-shaft. Inasmuch as the motor projects clear
+of the fuselage proper there is plenty of room back of<span class='pagenum'><a name="Page_344"
+id="Page_344">[344]</a></span><span class='pagenum'><a name="Page_343" id="Page_343"></a></span>
+the front spider plate to install the auxiliary parts such
+as the oil pump, air pump and ignition magneto and also
+the fuel and oil containers. The diagram given at <a href="#Fig156">Fig.
+156</a> shows how a Gnome &#8220;monosoupape&#8221; engine is installed
+on the anchorage plates and it also outlines clearly
+the piping necessary to convey the oil and fuel and also
+the air-piping needed to put pressure on both fuel and
+oil tanks to insure positive supply of these liquids which
+may be carried in tanks placed lower than the motor in
+some installations. The diagram given at <a href="#Fig157">Figs. 157</a> and
+<a href="#Fig158">158</a> shows other mountings of Gnome engines and are
+self-explanatory. The simple mounting possible when the
+Anzani ten-cylinder radial fixed type engine is used given
+at <a href="#Fig159">Fig. 159</a>. The front end of the fuselage is provided
+with a substantial pressed steel plate having members
+projecting from it which may be bolted to the longerons.
+The bolts that hold the two halves of the crank-case
+together project through the steel plate and hold the
+engine securely to the front end of the fuselage.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig158" id="Fig158"></a>
+<img src="images/illo340.png" alt="Fig. 158" width="500" height="309" />
+<p class="caption">Fig. 158.&mdash;How Gnome Rotary Motor May Be Attached to Airplane
+Fuselage Members.</p></div>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig159" id="Fig159"></a>
+<img src="images/illo341.png" alt="Fig. 159" width="350" height="496" />
+<p class="caption">Fig. 159.&mdash;How Anzani Ten-Cylinder Radial Engine is Installed to Plate
+Securely Attached to Front End of Tractor Airplane Fuselage.</p></div>
+
+<p class='pagenum'><a name="Page_345" id="Page_345">[345]</a></p>
+
+<h3><a name="SecX_10" id="SecX_10"></a>PRACTICAL HINTS TO LOCATE ENGINE TROUBLES</h3>
+
+<p>One who is not thoroughly familiar with engine construction
+will seldom locate troubles by haphazard experimenting
+and it is only by a systematic search that the
+cause can be discovered and the defects eliminated. In
+this chapter the writer proposes to outline some of the
+most common power-plant troubles and to give sufficient
+advice to enable those who are not thoroughly informed
+to locate them by a logical process of elimination. The
+internal-combustion motor, which is the power plant of
+all gasoline automobiles as well as airplanes, is composed
+of a number of distinct groups, which in turn include distinct
+components. These various appliances are so closely
+related to each other that defective action of any one may
+interrupt the operation of the entire power plant. Some
+of the auxiliary groups are more necessary than others
+and the power plant will continue to operate for a time
+even after the failure of some important parts of some
+of the auxiliary groups. The gasoline engine in itself is<span class='pagenum'><a name="Page_346" id="Page_346">[346]</a></span>
+a complete mechanism, but it is evident that it cannot
+deliver any power without some means of supplying gas
+to the cylinders and igniting the compressed gas charge
+after it has been compressed in the cylinders. From this<span class='pagenum'><a name="Page_347" id="Page_347">[347]</a></span>
+it is patent that the ignition and carburetion systems are
+just as essential parts of the power plant as the piston,
+connecting rod, or cylinder of the motor. The failure of
+either the carburetor or igniting means to function properly
+will be immediately apparent by faulty action of the
+power plant.</p>
+
+<p>To insure that the motor will continue to operate it
+is necessary to keep it from overheating by some form of
+cooling system and to supply oil to the moving parts to
+reduce friction. The cooling and lubrication groups are
+not so important as carburetion and ignition, as the engine
+would run for a limited period of time even should
+the cooling system fail or the oil supply cease. It would
+only be a few moments, however, before the engine would
+overheat if the cooling system was at fault, and the parts
+seize if the lubricating system should fail. Any derangement
+in the carburetor or ignition mechanism would manifest
+itself at once because the engine operation would be
+affected, but a defect in the cooling or oiling system would
+not be noticed so readily.</p>
+
+<p>The careful aviator will always inspect the motor
+mechanism before starting on a trip of any consequence,
+and if inspection is carefully carried out and loose parts
+tightened it is seldom that irregular operation will be
+found due to actual breakage of any of the components
+of the mechanism. Deterioration due to natural causes
+matures slowly, and sufficient warning is always given
+when parts begin to wear so satisfactory repairs may be
+promptly made before serious derangement or failure is
+manifested.</p>
+
+<h3><a name="SecX_11" id="SecX_11"></a>A TYPICAL ENGINE STOPPAGE ANALYZED</h3>
+
+<p>Before describing the points that may fail in the various
+auxiliary systems it will be well to assume a typical
+case of engine failure and show the process of locating
+the trouble in a systematic manner by indicating the
+various steps which are in logical order and which could<span class='pagenum'><a name="Page_348" id="Page_348">[348]</a></span>
+reasonably be followed. In any case of engine failure the
+ignition system, motor compression, and carburetor should
+be tested first. If the ignition system is functioning properly
+one should determine the amount of compression in
+all cylinders and if this is satisfactory the carbureting
+group should be tested. If the ignition system is working
+properly and there is a decided resistance in the cylinders
+when the propeller is turned, proving that there is good
+compression, one may suspect the carburetor.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig160" id="Fig160"></a>
+<p class="leftlink"><a href="images/large343.png">Large<br />image<br />(78 kB).</a></p>
+<img src="images/illo343.png" alt="Fig. 160" width="500" height="345" />
+<p class="caption">Fig. 160.&mdash;Side Elevation of Thomas 135 Horse-Power Airplane Engine,
+Giving Important Dimensions.</p></div>
+
+<p>If the carburetor appears to be in good condition, the
+trouble may be caused by the ignition being out of time,
+which condition is possible when the magneto timing gear
+or coupling is attached to the armature shaft by a taper
+and nut retention instead of the more positive key or
+taper-pin fastening. It is possible that the inlet manifold
+may be broken or perforated, that the exhaust valve is
+stuck on its seat because of a broken or bent stem, broken
+or loose cam, or failure of the cam-shaft drive because
+the teeth are stripped from the engine shaft or cam-shaft<span class='pagenum'><a name="Page_349" id="Page_349">[349]</a></span>
+gears; or because the key or other fastening on either
+gear has failed, allowing that member to turn independently
+of the shaft to which it normally is attached. The
+gasoline feed pipe may be clogged or broken, the fuel
+supply may be depleted, or the shut-off cock in the gasoline
+line may have jarred closed. The gasoline filter may
+be filled with dirt or water which prevents passage of the
+fuel.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig161" id="Fig161"></a>
+<p class="leftlink"><a href="images/large344.png">Large<br />image<br />(84 kB).</a></p>
+<img src="images/illo344.png" alt="Fig. 161" width="450" height="497" />
+<p class="caption">Fig. 161.&mdash;Front Elevation of Thomas-Morse 135 Horse-Power Aeromotor,
+Showing Main Dimensions.</p></div>
+
+<p>The defects outlined above, except the failure of the<span class='pagenum'><a name="Page_350" id="Page_350">[350]</a></span>
+gasoline supply, are very rare, and if the container is
+found to contain fuel and the pipe line to be clear to the
+carburetor, it is safe to assume the vaporizing device is
+at fault. If fuel continually runs out of the mixing chamber
+the carburetor is said to be flooded. This condition
+results from failure of the shut-off needle to seat properly
+or from a punctured hollow metal float or a gasoline-soaked
+cork float. It is possible that not enough gasoline
+is present in the float chamber. If the passage controlled
+by the float-needle valve is clogged or if the float was
+badly out of adjustment, this contingency would be probable.
+When the carburetor is examined, if the gasoline
+level appears to be at the proper height, one may suspect
+that a particle of lint, or dust, or fine scale, or rust from
+the gasoline tank has clogged the bore of the jet in the
+mixing chamber.</p>
+
+<p class='pagenum' style="margin-top: -1.5em;"><a name="Page_351" id="Page_351">[351]</a></p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig162" id="Fig162"></a>
+<p class="leftlink"><a href="images/large346.png">Large<br />image<br />(77 kB).</a></p>
+<img src="images/illo346.png" alt="Fig. 162" width="600" height="305" />
+<p class="caption">Fig. 162.&mdash;Front and Side Elevations of Sturtevant Airplane Engine, Giving Principal Dimensions to Facilitate
+Installation.</p></div>
+
+<p>If the ignition system and carburetor appear to be in
+good working order, and the hand crank shows that there
+is no compression in one or more of the cylinders, it
+means some defect in the valve system. If the engine is
+a multiple-cylinder type and one finds poor compression
+in all of the cylinders it may be due to the rare defect
+of improper valve timing. This may be caused by a gear
+having altered its position on the cam-shaft or crank-shaft,
+because of a sheared key or pin having permitted
+the gear to turn about half of a revolution and then
+having caught and held the gear in place by a broken or
+jagged end so that cam-shaft would turn, but the valves
+open at the wrong time. If but one of the cylinders is
+at fault and the rest appear to have good compression
+the trouble may be due to a defective condition either inside
+or outside of that cylinder. The external parts may
+be inspected easily, so the following should be looked for:
+a broken valve, a warped valve-head, broken valve-springs,
+sticking or bent valve-stems, dirt under valve-seat, leak
+at valve-chamber cap or spark-plug gasket. Defective
+priming cock, cracked cylinder head (rarely occurs), leak
+through cracked spark-plug insulation, valve-plunger<span class='pagenum'><a name="Page_352" id="Page_352">[352]</a></span>
+stuck in the guide, lack of clearance between valve-stem
+end and top of plunger caused by loose adjusting screw
+which has worked up and kept the valve from seating.
+The faulty compression may be due to defects inside the
+motor. The piston-head may be cracked (rarely occurs),
+piston rings may be broken, the slots in the piston rings
+may be in line, the rings may have lost their elasticity
+or have become gummed in the grooves of the piston, or
+the piston and cylinder walls may be badly scored by a
+loose wrist pin or by defective lubrication. If the motor
+is a type with a separate head it is possible the gasket
+or packing between the cylinder and combustion chamber
+may leak, either admitting water to the cylinder or allowing
+compression to escape.</p>
+
+<h3>CONDITIONS THAT CAUSE FAILURE OF IGNITION SYSTEM</h3>
+
+<p>If the first test of the motor had showed that the compression
+was as it should be and that there were no serious
+mechanical defects and there was plenty of gasoline
+at the carburetor, this would have demonstrated that the
+ignition system was not functioning properly. If a battery
+is employed to supply current the first step is to take
+the spark-plugs out of the cylinders and test the system
+by turning over the engine by hand. If there is no spark
+in any of the plugs, this may be considered a positive
+indication that there is a broken main current lead from
+the battery, a defective ground connection, a loose battery
+terminal, or a broken connector. If none of these
+conditions are present, it is safe to say that the battery
+is no longer capable of delivering current. While magneto
+ignition is generally used on airplane engines, there
+is apt to be some development of battery ignition, especially
+on engines equipped with electric self-starters which
+are now being experimented with. The spark-plugs may
+be short circuited by cracked insulation or carbon and
+oil deposits around the electrode. The secondary wires
+may be broken or have defective insulation which permits<span class='pagenum'><a name="Page_353" id="Page_353">[353]</a></span>
+the current to ground to some metal part of the fuselage
+or motor. The electrodes of the spark-plug may be too
+far apart to permit a spark to overcome the resistance
+of the compressed gas, even if a spark jumps the air
+space, when the plug is laid on the cylinder.</p>
+
+<p>If magnetos are fitted as is usually the case at present
+and a spark is obtained between the points of the plug
+and that device or the wire leading to it from the magneto
+is in proper condition, the trouble is probably caused by
+the magneto being out of time. This may result if the
+driving gear is loose on the armature-shaft or crank-shaft,
+and is a rare occurrence. If no spark is produced
+at the plugs the secondary wire may be broken, the ground
+wire may make contact with some metallic portion of the
+chassis before it reaches the switch, the carbon collecting
+brushes may be broken or not making contact, the contact
+points of the make-and-break device may be out of adjustment,
+the wiring may be attached to wrong terminals, the
+distributor filled with metallic particles, carbon, dust or
+oil accumulations, the distributor contacts may not be
+making proper connection because of wear and there may
+be a more serious derangement, such as a burned out
+secondary winding or a punctured condenser.</p>
+
+<p>If the motor runs intermittently, <i>i.e.</i>, starts and runs
+only a few revolutions, aside from the conditions previously
+outlined, defective operation may be due to seizing
+between parts because of insufficient oil or deficient
+cooling, too much oil in the crank-case which fouls the
+cylinder after the crank-shaft has revolved a few turns,
+and derangements in the ignition or carburetion systems
+that may be easily remedied. There are a number of
+defective conditions which may exist in the ignition group,
+that will result in &#8220;skipping&#8221; or irregular operation and
+the following points should be considered first: weak
+source of current due to worn out dry cells or discharged
+storage batteries; weak magnets in magneto, or defective
+contacts at magneto; dirt in magneto distributor or poor
+contact at collecting brushes. Dirty or cracked insulator<span class='pagenum'><a name="Page_354" id="Page_354">[354]</a></span>
+at spark-plug will cause short circuit and can only be
+detected by careful examination. The following points
+should also be checked over when the plug is inspected:
+Excessive space between electrodes, points too close together,
+loose central electrodes, or loose point on plug
+body, soot or oil particles between electrodes, or on the
+surface of the insulator, cracked insulator, oil or water
+on outside of insulator. Short circuits in the condenser
+or internal wiring of induction coils or magnetos, which
+are fortunately not common, can seldom be remedied except
+at the factory where these devices were made. If an
+engine stops suddenly and the defect is in the ignition
+system the trouble is usually never more serious than a
+broken or loose wire. This may be easily located by inspecting
+the wiring at the terminals. Irregular operation
+or misfiring is harder to locate because the trouble can
+only be found after the many possible defective conditions
+have been checked over, one by one.</p>
+
+<h3>COMMON DEFECTS IN FUEL SYSTEMS</h3>
+
+<p>Defective carburetion often causes misfiring or irregular
+operation. The common derangement of the components
+of the fuel system that are common enough to
+warrant suspicion and the best methods for their location
+follows: First, disconnect the feed pipe from the carburetor
+and see if the gasoline flows freely from the tank.
+If the stream coming out of the pipe is not the full size
+of the orifice it is an indication that the pipe is clogged
+with dirt or that there is an accumulation of rust, scale,
+or lint in the strainer screens of the filter. It is also
+possible that the fuel shut-off valve may be wholly or
+partly closed. If the gasoline flows by gravity the liquid
+may be air bound in the tank, while if a pressure-feed
+system is utilized the tank may leak so that it does not
+retain pressure; the check valve retaining the pressure
+may be defective or the pipe conveying the air or gas
+under pressure to the tank may be clogged.</p>
+
+<p><span class='pagenum'><a name="Page_355" id="Page_355">[355]</a></span>If the gasoline flows from the pipe in a steady stream
+the carburetor demands examination. There may be dirt
+or water in the float chamber, which will constrict the
+passage between the float chamber and the spray nozzle,
+or a particle of foreign matter may have entered the
+nozzle and stopped up the fine holes therein. The float
+may bind on its guide, the needle valve regulating the
+gasoline-inlet opening in bowl may stick to its seat. Any
+of the conditions mentioned would cut down the gasoline
+supply and the engine would not receive sufficient quantities
+of gas. The air-valve spring may be weak or the
+air valve broken. The gasoline-adjusting needle may be
+loose and jar out of adjustment, or the air-valve spring-adjusting
+nuts may be such a poor fit on the stem that
+adjustments will not be retained. These instructions apply
+only to carburetors having air valves and mixture
+regulating means which are used only in rare instances
+in airplane work. Air may leak in through the manifold,
+due to a porous casting, or leaky joints in a built up form
+and dilute the mixture. The air-intake dust screen may
+be so clogged with dirt and lint that not enough air will
+pass through the mesh. Water or sediment in the gasoline
+will cause misfiring because the fuel feed varies when
+the water or dirt constricts the standpipe bore.</p>
+
+<p>It is possible that the carburetor may be out of adjustment.
+If clouds of black smoke are emitted at the
+exhaust pipe it is positive indication that too much gasoline
+is being supplied the mixture and the supply should
+be cut down by screwing in the needle valve on types
+where this method of regulation is provided, and by making
+sure that the fuel level is at the proper height, or that
+the proper nozzle is used in those forms where the spray
+nozzle has no means of adjustment. If the mixture contains
+too much air there will be a pronounced popping
+back in the carburetor. This may be overcome by screwing
+in the air-valve adjustment so the spring tension is
+increased or by slightly opening up the gasoline-supply
+regulation needle. When a carburetor is properly adjusted<span class='pagenum'><a name="Page_356" id="Page_356">[356]</a></span>
+and the mixture delivered the cylinder burns properly,
+the exhaust gas will be clean and free from the
+objectionable odor present when gasoline is burned in
+excess.</p>
+
+<p>The character of combustion may be judged by the
+color of the flame which issues from it when the engine
+is running with an open throttle after nightfall. If the
+flame is red, it indicates too much gasoline. If yellowish,
+it shows an excess of air, while a properly proportioned
+mixture will be evidenced by a pronounced blue flame,
+such as given by a gas-stove burner.</p>
+
+<p>The Duplex Model O. D. Zenith carburetor used upon
+most of the six- and eight-cylinder airplane engines consists
+of a single float chamber, and a single air intake,
+joined to two separate and distinct spray nozzles, venturi
+and idling adjustments. It is to be noted that as the
+carburetor barrels are arranged side by side, both valves
+are mounted on the same shaft, and work in unison
+through a single operating lever. It is not necessary to
+alter their position. In order to make the engine idle
+well, it is essential that the ignition, especially the spark-plugs,
+should be in good condition. The gaskets between
+carburetor and manifold, and between manifold and cylinders
+should be absolutely air-tight. The adjustment for
+low speed on the carburetor is made by turning in or out
+the two knurled screws, placed one on each side of the
+float chamber. After starting the engine and allowing it
+to become thoroughly warmed, one side of the carburetor
+should be adjusted so that the three cylinders it affects
+fire properly at low speed. The other side should be
+adjusted in the same manner until all six cylinders fire
+perfectly at low speed. As the adjustment is changed
+on the knurled screw a difference in the idling of the engine
+should be noticed. If the engine begins to run evenly
+or speeds up it shows that the mixture becomes right in
+its proportion.</p>
+
+<p>Be sure the butterfly throttle is closed as far as possible
+by screwing out the stop screw which regulates the<span class='pagenum'><a name="Page_357" id="Page_357">[357]</a></span>
+closed position for idling. Care should be taken to have
+the butterfly held firmly against this stop screw at all
+times while idling engine. If three cylinders seem to run
+irregularly after changing the position of the butterfly,
+still another adjustment may have to be made with the
+knurled screw. Unscrewing this makes the mixture
+leaner. Screwing in closes off some of the air supply to
+the idling jet, making it richer. After one side has been
+made to idle satisfactorily repeat the same procedure with
+the opposite three cylinders. In other words, each side
+should be idled independently to about the same speed.</p>
+
+<p>Remember that the main jet and compensating jet
+have no appreciable effect on the idling of the engine.
+The idling mixture is drawn directly through the opening
+determined by the knurled screw and enters the carburetor
+barrel through the small hole at the edge of each
+butterfly. This is called the priming hole and is only
+effective during idling. Beyond that point the suction is
+transferred to the main jet and compensator, which controls
+the power of the engine beyond the idling position
+of the throttle.</p>
+
+<h3>DEFECTS IN OILING SYSTEMS</h3>
+
+<p>While troubles existing in the ignition or carburetion
+groups are usually denoted by imperfect operation of
+the motor, such as lost power, and misfiring, derangements
+of the lubrication or cooling systems are usually
+evident by overheating, diminution in engine capacity, or
+noisy operation. Overheating may be caused by poor
+carburetion as much as by deficient cooling or insufficient
+oiling. When the oiling group is not functioning as it
+should the friction between the motor parts produces heat.
+If the cooling system is in proper condition, as will be
+evidenced by the condition of the water in the radiator,
+and the carburetion group appears to be in good condition,
+the overheating is probably caused by some defect
+in the oiling system.</p>
+
+<p>The conditions that most commonly result in poor<span class='pagenum'><a name="Page_358" id="Page_358">[358]</a></span>
+lubrication are: Insufficient oil in the engine crank-case
+or sump, broken or clogged oil pipes, screen at filter filled
+with lint or dirt, broken oil pump, or defective oil-pump
+drive. The supply of oil may be reduced by a defective
+inlet or discharge-check valve at the mechanical oiler or
+worn pumps. A clogged oil passage or pipe leading to
+an important bearing point will cause trouble because
+the oil cannot get between the working surfaces. It is
+well to remember that much of the trouble caused by
+defective oiling may be prevented by using only the best
+grades of lubricant, and even if all parts of the oil system
+are working properly, oils of poor quality will cause
+friction and overheating.</p>
+
+<h3>DEFECTS IN COOLING SYSTEMS OUTLINED</h3>
+
+<p>Cooling systems are very simple and are not liable to
+give trouble as a rule if the radiator is kept full of clean
+water and the circulation is not impeded. When overheating
+is due to defective cooling the most common
+troubles are those that impede water circulation. If the
+radiator is clogged or the piping of water jackets filled
+with rust or sediment the speed of water circulation will
+be slow, which will also be the case if the water pump or
+its driving means fail. Any scale or sediment in the water
+jackets or in the piping or radiator passages will reduce
+the heat conductivity of the metal exposed to the air, and
+the water will not be cooled as quickly as though the scale
+was not present.</p>
+
+<p>The rubber hose often used in making the flexible
+connections demanded between the radiator and water
+manifolds of the engine may deteriorate inside and particles
+of rubber hang down that will reduce the area of
+the passage. The grease from the grease cups mounted
+on the pump-shaft bearing to lubricate that member often
+finds its way into the water system and rots the inner
+walls of the rubber hose, this resulting in strips of the
+partly decomposed rubber lining hanging down and restricting<span class='pagenum'><a name="Page_359" id="Page_359">[359]</a></span>
+the passage. The cooling system is prone to
+overheat after antifreezing solutions of which calcium
+chloride forms a part have been used. This is due to
+the formation of crystals of salt in the radiator passages
+or water jackets, and these crystals can only be dissolved
+by suitable chemical means, or removed by scraping when
+the construction permits.</p>
+
+<p>Overheating is often caused by some condition in the
+fuel system that produces too rich or too lean mixture.
+Excess gasoline may be supplied if any of the following
+conditions are present: Bore of spray nozzle or standpipe
+too large, auxiliary air-valve spring too tight, gasoline
+level too high, loose regulating valve, fuel-soaked
+cork float, punctured sheet-metal float, dirt under float
+control shut-off valve or insufficient air supply because
+of a clogged air screen. If pressure feed is utilized there
+may be too much pressure in the tank, or the float controlled
+mechanism operating the shut-off in the float bowl
+of the carburetor may not act quickly enough.</p>
+
+<h3>SOME CAUSES OF NOISY OPERATION</h3>
+
+<p>There are a number of power-plant derangements
+which give positive indication because of noisy operation.
+Any knocking or rattling sounds are usually produced by
+wear in connecting rods or main bearings of the engine,
+though sometimes a sharp metallic knock, which is very
+much the same as that produced by a loose bearing, is due
+to carbon deposits in the cylinder heads, or premature
+ignition due to advanced spark-time lever. Squeaking
+sounds invariably indicate dry bearings, and whenever
+such a sound is heard it should be immediately located
+and oil applied to the parts thus denoting their dry condition.
+Whistling or blowing sounds are produced by
+leaks, either in the engine itself or in the gas manifolds.
+A sharp whistle denotes the escape of gas under pressure
+and is usually caused by a defective packing or gasket
+that seals a portion of the combustion chamber or that is<span class='pagenum'><a name="Page_360" id="Page_360">[360]</a></span>
+used for a joint as the exhaust manifold. A blowing
+sound indicates a leaky packing in crank-case. Grinding
+noises in the motor are usually caused by the timing gears
+and will obtain if these gears are dry or if they have become
+worn. Whenever a loud knocking sound is heard
+careful inspection should be made to locate the cause of
+the trouble. Much harm may be done in a few minutes
+if the engine is run with loose connecting rod or bearings
+that would be prevented by taking up the wear or looseness
+between the parts by some means of adjustment.</p>
+
+<h3>BRIEF SUMMARY OF HINTS FOR STARTING ENGINE</h3>
+
+<p>First make sure that all cylinders have compression.
+To ascertain this, open pet cocks of all cylinders except
+the one to be tested, crank over motor and see that a
+strong opposition to cranking is met with once in two
+revolutions. If motor has no pet cocks, crank and notice
+that oppositions are met at equal distances, two to every
+revolution of the starting crank in a four-cylinder motor.
+If compression is lacking, examine the parts of the cylinder
+or cylinders at fault in the following order, trying to
+start the motor whenever any one fault is found and
+remedied. See that the valve push rods or rocker arms
+do not touch valve stems for more than approximately
+<sup>1</sup>&#8260;<sub>2</sub> revolution in every 2 revolutions, and that there is not
+more than .010 to .020 inch clearance between them depending
+on the make of the motor. Make sure that the
+exhaust valve seats. To determine this examine the
+spring and see that it is connected to the valve stem
+properly. Take out valve and see that there is no obstruction,
+such as carbon, on its seat. See that valve
+works freely in its guide. Examine inlet valve in same
+manner. Listen for hissing sound while cranking motor
+for leaks at other places.</p>
+
+<p>Make sure that a spark occurs in each cylinder as
+follows: If magneto or magneto and battery with non-vibrating
+coil is used: Disconnect wire from spark-plug,<span class='pagenum'><a name="Page_361" id="Page_361">[361]</a></span>
+hold end about <sup>1</sup>&#8260;<sub>8</sub> inch from cylinder or terminal of spark-plug.
+Have motor cranked briskly and see if spark occurs.
+Examine adjustment of interrupter points. See that
+wires are placed correctly and not short circuited. Take
+out spark-plug and lay it on the cylinder, being careful
+that base of plug only touches the cylinder and that ignition
+wire is connected. Have motor cranked briskly and
+see if spark occurs. Check timing of magneto and see
+that all brushes are making contact.</p>
+
+<p>See if there is gasoline in the carburetor. See that
+there is gasoline in the tank. Examine valve at tank.
+Prime carburetor and see that spray nozzle passage is
+clear. Be sure throttle is open. Prime cylinders by putting
+about a teaspoonful of gasoline in through pet cock
+or spark-plug opening. Adjust carburetor if necessary.</p>
+
+<h3><a name="SecX_12" id="SecX_12"></a>LOCATION OF ENGINE TROUBLES MADE EASY</h3>
+
+<p>The following tabulation has been prepared and originated
+by the writer to outline in a simple manner the
+various troubles and derangements that interfere with
+efficient internal-combustion engine action. The parts
+and their functions are practically the same in all gas or
+gasoline engines of the four-cycle type, and the general
+instructions given apply just as well to all hydro-carbon
+engines, even if the parts differ in form materially. The
+essential components are clearly indicated in the many
+part sectional drawings in this book so they may be
+easily recognized. The various defects that may materialize
+are tabulated in a manner that makes for ready
+reference, and the various defective conditions are found
+opposite the part affected, and under a heading that denotes
+the main trouble to which the others are contributing
+causes. The various symptoms denoting the
+individual troubles outlined are given to facilitate their
+recognition in a positive manner.</p>
+
+<p>Brief note is also made of the remedies for the restoration
+of the defective part or condition. It is apparent<span class='pagenum'><a name="Page_362" id="Page_362">[362]</a></span>
+that a table of this character is intended merely as a
+guide, and it is a compilation of practically all the known
+troubles that may materialize in gas-engine operation.
+While most of the defects outlined are common enough
+to warrant suspicion, they will never exist in an engine
+all at the same time, and it will be necessary to make a
+systematic search for such of those as exist.</p>
+
+<p>To use the list advantageously, it is necessary to know
+one main trouble easily recognized. For example, if the
+power plant is noisy, look for the possible troubles under
+the head of Noisy Operation; if it lacks capacity, the
+derangement will undoubtedly be found under the head of
+Lost Power. It is assumed in all cases that the trouble
+exists in the power plant or its components, and not in
+the auxiliary members of the ignition, carburetion, lubrication,
+or cooling systems. The novice and student will
+readily recognize the parts of the average aviation engine
+by referring to the very complete and clearly lettered
+illustrations of mechanism given in many parts of this
+treatise.</p>
+
+<table summary="Table p. 363-368">
+
+<tr>
+<td colspan="4" class="center">LOST POWER AND OVERHEATING<span class='pagenum'><a name="Page_363" id="Page_363">[363]</a></span></td>
+</tr>
+
+<tr class="bb">
+<td colspan="4" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr class="bb">
+<td class="center br" style="width: 25%;">PART AFFECTED</td>
+<td class="center br" style="width: 25%;">NATURE OF TROUBLE</td>
+<td class="center br" style="width: 25%;">SYMPTOMS AND EFFECTS</td>
+<td class="center" style="width: 25%;">REMEDY</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Water Pipe Joint.</td>
+<td class="left top padl1 padr1 br">Loose.</td>
+<td class="left top padl1 padr1 br">Loss of water, heating.</td>
+<td class="left top padl1 padr1">Tighten bolts, replace gaskets.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Spark Plug.</td>
+<td class="left top padl1 padr1 br">Leakage in threads, insulation, or packing.</td>
+<td class="left top padl1 padr1 br">Loss of power. Hissing caused by escaping gas.</td>
+<td class="left top padl1 padr1">Replace insulation if defective, screw down tighter.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Compression Release Cock.</td>
+<td class="left top padl1 padr1 br">Leak in threads. Leak in fitting.</td>
+<td class="left top padl1 padr1 br">Loss of power. Whistling or hissing.</td>
+<td class="left top padl1 padr1">Tighten if loose. Grind fitting to new seating in body.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Combustion Chamber.</td>
+<td class="left top padl1 padr1 br">Crack or blowhole. Roughness. Carbon deposits. Sharp edges.</td>
+<td class="left top padl1 padr1 br">Loss of compression. Preignition.</td>
+<td class="left top padl1 padr1">Fill by welding. Smooth out roughness. Scrape out or dissolve carbon.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Chamber Cap.</td>
+<td class="left top padl1 padr1 br">Leak in threads. Defective gasket.</td>
+<td class="left top padl1 padr1 br">Loss of compression. Hissing.</td>
+<td class="left top padl1 padr1">Remove. Apply pipe compound to threads and replace. Use new gasket or packing.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Head.</td>
+<td class="left top padl1 padr1 br">Warped. Scored or pitted. Carbonized. Covered with scale. Loose on stem (two-piece valves only).</td>
+<td class="left top padl1 padr1 br">Loss of compression.</td>
+<td class="left top padl1 padr1">True up in lathe. Grind to seat. Scrape off. Smooth with emery cloth. Tighten by riveting.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Seat.</td>
+<td class="left top padl1 padr1 br">Warped or pitted. Covered with carbon. Foreign matter between valve and seat.</td>
+<td class="left top padl1 padr1 br">Loss of compression.</td>
+<td class="left top padl1 padr1">Use reseating reamer. Clean off and grind valve to seat.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Stem.</td>
+<td class="left top padl1 padr1 br">Covered with scale. Bent. Binding in guide. Stuck in guide.</td>
+<td class="left top padl1 padr1 br">Valve does not close. Loss of compression.</td>
+<td class="left top padl1 padr1">Clean with emery cloth; straighten. True up and smooth off. free with kerosene.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Stem Guide.</td>
+<td class="left top padl1 padr1 br">Burnt or rough. Loose in valve chamber.</td>
+<td class="left top padl1 padr1 br">Valve may stick. Action irregular.</td>
+<td class="left top padl1 padr1">Clean out hole. Screw in tighter.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Spring.</td>
+<td class="left top padl1 padr1 br">Weak or broken.</td>
+<td class="left top padl1 padr1 br">Valve does not close.</td>
+<td>&nbsp;</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Operating Plunger.</td>
+<td class="left top padl1 padr1 br">Loose in guide. Too much clearance between valve stem.</td>
+<td class="left top padl1 padr1 br">Valve action poor. Lift insufficient.</td>
+<td class="left top padl1 padr1">Replace with new. Adjust screw closer.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Lift Adjusting Screw.</td>
+<td class="left top padl1 padr1 br">Threads stripped. Too near valve. Too far from valve.</td>
+<td class="left top padl1 padr1 br">Poor valve action.</td>
+<td class="left top padl1 padr1">Replace with new. Adjust with proper reference to valve stem.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Lift Cam.<span class='pagenum'><a name="Page_364" id="Page_364">[364]</a></span></td>
+<td class="left top padl1 padr1 br">Worn cam contour. Loose on shaft. Out of time.</td>
+<td class="left top padl1 padr1 br">Not enough valve lift. Will not lift valve. Valve opens at wrong time.</td>
+<td class="left top padl1 padr1">Replace with new. Replace pins or keys. Set to open properly.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Cam-shaft.</td>
+<td class="left top padl1 padr1 br">Sprung or twisted.</td>
+<td class="left top padl1 padr1 br">Valves out of time.</td>
+<td class="left top padl1 padr1">Straighten.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Cam-shaft Bushing.</td>
+<td class="left top padl1 padr1 br">Worn.</td>
+<td class="left top padl1 padr1 br">Not enough valve lift.</td>
+<td class="left top padl1 padr1">Replace.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Cam-shaft Drive Gear.</td>
+<td class="left top padl1 padr1 br">Loose on shaft. Out of time. Worn or broken teeth.</td>
+<td class="left top padl1 padr1 br">Irregular valve action.</td>
+<td class="left top padl1 padr1">Fasten securely. Time properly. Replace with new.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Cam Fastenings.</td>
+<td class="left top padl1 padr1 br">Worn or broken.</td>
+<td class="left top padl1 padr1 br">Valves out of time.</td>
+<td class="left top padl1 padr1">Replace with new.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Cylinder Wall.</td>
+<td class="left top padl1 padr1 br">Scored, gas leaks. Poor lubrication causes friction.</td>
+<td class="left top padl1 padr1 br">Poor compression. Overheating.</td>
+<td class="left top padl1 padr1">Grind out bore. Repair oiling system.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Piston.</td>
+<td class="left top padl1 padr1 br">Binds in cylinder. Walls scored. Worn out of round.</td>
+<td class="left top padl1 padr1 br">Overheating. Poor compression.</td>
+<td class="left top padl1 padr1">Lap off excess metal. Replace with new.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Piston Rings.</td>
+<td class="left top padl1 padr1 br">Loss of spring. Loose in grooves. Scored. Worn or broken. Slots in line.</td>
+<td class="left top padl1 padr1 br">Loss of compression. Gas blows by.</td>
+<td class="left top padl1 padr1">Peen ring or replace. Fit new rings. Grind smooth. Replace. Turn slots apart.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">&nbsp;</td>
+<td class="left top padl1 padr1 br">Carbon in grooves. Insufficient opening. Binding on cylinder.</td>
+<td class="left top padl1 padr1 br">Overheating because of friction.</td>
+<td class="left top padl1 padr1">Remove deposits. File slot. Grind or lap to fit cylinder bore.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Wristpin.</td>
+<td class="left top padl1 padr1 br">Loose, scores cylinder.</td>
+<td class="left top padl1 padr1 br">Loss of compression.</td>
+<td class="left top padl1 padr1">Fasten securely. Replace cylinder if groove is deep.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Crank-shaft.</td>
+<td class="left top padl1 padr1 br">Scored or rough on journals. Sprung.</td>
+<td class="left top padl1 padr1 br">Overheating because of friction.</td>
+<td class="left top padl1 padr1">Smooth up. Straighten.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Crank Bearings. Main Bearings.</td>
+<td class="left top padl1 padr1 br">Adjusted too tight. Defective oiling. Brasses burned.</td>
+<td class="left top padl1 padr1 br">Overheating because of friction.</td>
+<td class="left top padl1 padr1">Adjust freely, clean out oil holes and enlarge oil grooves.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Oil Sump.</td>
+<td class="left top padl1 padr1 br">Insufficient oil. Poor lubricant. Dirty oil.</td>
+<td class="left top padl1 padr1 br">Overheating.</td>
+<td class="left top padl1 padr1">Replenish supply. Use best oil. Wash out with kerosene; put in clean oil.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Water Space. Water Pipes.</td>
+<td class="left top padl1 padr1 br">Clogged with sediment or scale.</td>
+<td class="left top padl1 padr1 br">Overheating.</td>
+<td class="left top padl1 padr1">Dissolve foreign matter and remove.</td>
+</tr>
+
+<tr class="bb">
+<td class="left top padl1 padr1 br">Piston Head.</td>
+<td class="left top padl1 padr1 br">Cracked (rare). Carbon deposits.</td>
+<td class="left top padl1 padr1 br">Loss of compression. Preignition.</td>
+<td class="left top padl1 padr1">Weld by autogenous process. Scrape off carbon accumulations.</td>
+</tr>
+
+<tr>
+<td colspan="4" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="4" class="center">NOISY OPERATION OF POWER PLANT<span class='pagenum'><a name="Page_365" id="Page_365">[365]</a></span></td>
+</tr>
+
+<tr class="bb">
+<td colspan="4" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr class="bb">
+<td class="center br">PART AFFECTED</td>
+<td class="center br">NATURE OF TROUBLE</td>
+<td class="center br">CHARACTER OF NOISE</td>
+<td class="center">REMEDY</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Compression Release Cock.</td>
+<td class="left top padl1 padr1 br">Leakage.</td>
+<td class="left top padl1 padr1 br">Hissing.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Spark Plug.</td>
+<td class="left top padl1 padr1 br">Leakage.</td>
+<td class="left top padl1 padr1 br">Hissing.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Chamber Cap.</td>
+<td class="left top padl1 padr1 br">Leakage.</td>
+<td class="left top padl1 padr1 br">Hiss or whistle.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Combustion Chamber.</td>
+<td class="left top padl1 padr1 br">Carbon deposits.</td>
+<td class="left top padl1 padr1 br">Knocking.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Inlet Valve Seat.</td>
+<td class="left top padl1 padr1 br">Defects previously given.</td>
+<td class="left top padl1 padr1 br">Popping in carburetor.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Head.</td>
+<td class="left top padl1 padr1 br">Loose on stem.</td>
+<td class="left top padl1 padr1 br">Clicking.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Stem. Valve Stem Guide.</td>
+<td class="left top padl1 padr1 br">Wear or looseness.</td>
+<td class="left top padl1 padr1 br">Rattle or clicking.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Inlet Valve.</td>
+<td class="left top padl1 padr1 br">Closes too late. Opens too early.</td>
+<td class="left top padl1 padr1 br">Blowback in carburetor.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Spring.</td>
+<td class="left top padl1 padr1 br">Weak or broken.</td>
+<td class="left top padl1 padr1 br">Blowback in carburetor.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Cylinder Casting.</td>
+<td class="left top padl1 padr1 br">Retaining bolts loose. Piston strikes at upper end.</td>
+<td class="left top padl1 padr1 br">Sharp metallic knock.</td>
+<td class="left top padl1 padr1">Tighten bolts. Round edges of piston top.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Cylinder Wall.</td>
+<td class="left top padl1 padr1 br">Scored.</td>
+<td class="left top padl1 padr1 br">Hissing.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Stem Clearance.</td>
+<td class="left top padl1 padr1 br">Too much. Too little (inlet valve).</td>
+<td class="left top padl1 padr1 br">Clicking. Blowback in carburetor.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Operating Plunger. Plunger Guide.</td>
+<td class="left top padl1 padr1 br">Looseness.</td>
+<td class="left top padl1 padr1 br">Rattle or clicking.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Timing Gears.</td>
+<td class="left top padl1 padr1 br">Loose on fastenings. Worn teeth. Meshed too deeply.</td>
+<td class="left top padl1 padr1 br">Metallic knock. Rattle. Grinding.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Cylinder or Piston.</td>
+<td class="left top padl1 padr1 br">No oil, or poor lubricant.</td>
+<td class="left top padl1 padr1 br">Grinding.</td>
+<td class="left top padl1 padr1">Repair oil system.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Cam.</td>
+<td class="left top padl1 padr1 br">Loose on shaft. Worn contour.</td>
+<td class="left top padl1 padr1 br">Metallic knock.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Cam-shaft Bearing.</td>
+<td class="left top padl1 padr1 br">Looseness or wear.</td>
+<td class="left top padl1 padr1 br">Slight knock.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Cam Fastening.</td>
+<td class="left top padl1 padr1 br">Looseness.</td>
+<td class="left top padl1 padr1 br">Clicking.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Piston.</td>
+<td class="left top padl1 padr1 br">Binding in cylinder. Worn oval, causes side slap in cylinder.</td>
+<td class="left top padl1 padr1 br">Grinding or dull squeak. Dull hammering.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Piston Head.</td>
+<td class="left top padl1 padr1 br">Carbon deposits.</td>
+<td class="left top padl1 padr1 br">Knocking.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Piston Rings.</td>
+<td class="left top padl1 padr1 br">Defective oiling. Leakage. Binding in cylinder.</td>
+<td class="left top padl1 padr1 br">Squeaking. Hissing. Grinding.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Wrist-pin.</td>
+<td class="left top padl1 padr1 br">Loose in piston. Worn.</td>
+<td class="left top padl1 padr1 br">Dull metallic knock.</td>
+<td class="left top padl1 padr1">Replace with new member.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Connecting Rod.<span class='pagenum'><a name="Page_366" id="Page_366">[366]</a></span></td>
+<td class="left top padl1 padr1 br">Wear in upper bushing. Wear at crank-pin. Side play in piston.</td>
+<td class="left top padl1 padr1 br">Distinct knock.</td>
+<td class="left top padl1 padr1">Adjust or replace. Scrape and fit. Use longer wrist-pin bushing.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Crank Bearings.</td>
+<td class="left top padl1 padr1 br">Looseness. Excessive end play. Binding, fitted too tight.</td>
+<td class="left top padl1 padr1 br">Metallic knock. Intermittent knock. Squeaking.</td>
+<td class="left top padl1 padr1">Refit bearings. Longer bushings needed. Insert shims to allow more play.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Main Bearings.</td>
+<td class="left top padl1 padr1 br">Looseness. Defective lubrication.</td>
+<td class="left top padl1 padr1 br">Metallic knock. Squeaking.</td>
+<td class="left top padl1 padr1">Fit brasses closer to shaft. Clean out oil holes and grooves.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Connecting Rod Bolts. Main Bearing Bolts.</td>
+<td class="left top padl1 padr1 br">Loose.</td>
+<td class="left top padl1 padr1 br">Sharp knock.</td>
+<td class="left top padl1 padr1">Tighten.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Crank-shaft.</td>
+<td class="left top padl1 padr1 br">Defective oiling.</td>
+<td class="left top padl1 padr1 br">Squeaking.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Engine Base.</td>
+<td class="left top padl1 padr1 br">Loose on frame.</td>
+<td class="left top padl1 padr1 br">Sharp pounding.</td>
+<td class="left top padl1 padr1">Tighten bolts.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Lower Half Crank-case.</td>
+<td class="left top padl1 padr1 br">Bolts loose.</td>
+<td class="left top padl1 padr1 br">Knocking.</td>
+<td class="left top padl1 padr1">Tighten bolts.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Fly-wheel.</td>
+<td class="left top padl1 padr1 br">Loose on crank-shaft.</td>
+<td class="left top padl1 padr1 br">Very sharp knock.</td>
+<td class="left top padl1 padr1">Tighten retention bolts or fit new keys.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Oil Sump.</td>
+<td class="left top padl1 padr1 br">Oil level too low. Poor lubricant.</td>
+<td class="left top padl1 padr1 br">Grinding and squeak in all bearings.</td>
+<td class="left top padl1 padr1">Replenish with best cylinder oil.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Plunger Retention Stirrups.</td>
+<td class="left top padl1 padr1 br">Looseness.</td>
+<td class="left top padl1 padr1 br">Clicking.</td>
+<td class="left top padl1 padr1">Tighten nuts.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Fan.</td>
+<td class="left top padl1 padr1 br">Blade loose. Blade strikes cooler.</td>
+<td class="left top padl1 padr1 br">Clicking or rattle.</td>
+<td class="left top padl1 padr1">Tighten. Bend back.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Exhaust Pipe Joints.</td>
+<td class="left top padl1 padr1 br">Leakage.</td>
+<td class="left top padl1 padr1 br">Sharp hissing.</td>
+<td class="left top padl1 padr1">Tighten or use new gasket.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Crank-case Packing.</td>
+<td class="left top padl1 padr1 br">Leakage.</td>
+<td class="left top padl1 padr1 br">Blowing sound.</td>
+<td class="left top padl1 padr1">Use new packing. Tighten bolts.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Water Pipe.</td>
+<td class="left top padl1 padr1 br">Leaks. Loss of water. Clogged with sediment.</td>
+<td class="left top padl1 padr1 br">Pounding because engine heats.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr class="bb">
+<td class="left top padl1 padr1 br">Water Jacket.</td>
+<td class="left top padl1 padr1 br">Clogged with sediment. Walls covered with scale.</td>
+<td class="left top padl1 padr1 br">Knocking because engine heats.</td>
+<td class="left top padl1 padr1">Dissolve scale and flush out water space with water under pressure.</td>
+</tr>
+
+<tr>
+<td colspan="4" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr>
+<td colspan="4" class="center">&#8220;SKIPPING&#8221; OR IRREGULAR OPERATION<span
+class='pagenum'><a name="Page_367" id="Page_367">[367]</a></span></td>
+</tr>
+
+<tr class="bb">
+<td colspan="4" class="blankrow">&nbsp;</td>
+</tr>
+
+<tr class="bb">
+<td class="center br">PART AFFECTED</td>
+<td class="center br">NATURE OF TROUBLE</td>
+<td class="center br">SYMPTOMS AND EFFECTS</td>
+<td class="center">REMEDY</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Compression Relief Cock.</td>
+<td class="left top padl1 padr1 br">Leak in threads or spigot.</td>
+<td class="left top padl1 padr1 br">Dilutes mixture with air, causes blowback.</td>
+<td class="left top padl1 padr1">Screw down tighter. Grind spigot to seat with emery.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Spark-Plug.</td>
+<td class="left top padl1 padr1 br">Leak in threads. Defective gasket. Cracked insulator. Points too near. Points covered with carbon.
+Too much air gap.</td>
+<td class="left top padl1 padr1 br">Dilutes mixture. Allows short circuit. No spark.</td>
+<td class="left top padl1 padr1">Screw down tighter. Replace with new. Set points <span
+class="nowrap"><sup>1</sup>&#8260;<sub>64</sub>&#8242;&#8242;</span> apart for magneto, <span
+class="nowrap"><sup>1</sup>&#8260;<sub>32</sub>&#8242;&#8242;</span> for battery spark.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Chamber Cap.</td>
+<td class="left top padl1 padr1 br">Leak in threads. Defective gasket.</td>
+<td class="left top padl1 padr1 br">Dilutes mixture by allowing air to enter cylinder on suction stroke.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Combustion Chamber.</td>
+<td class="left top padl1 padr1 br">Carbon deposits.</td>
+<td class="left top padl1 padr1 br">Preignition.</td>
+<td class="left top padl1 padr1">Scrape out.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Head.</td>
+<td class="left top padl1 padr1 br">Warped or pitted. Loose on stem.</td>
+<td class="left top padl1 padr1 br">Dilutes charge with poor air or gas.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Stem.</td>
+<td class="left top padl1 padr1 br">Binding in guide. Sticking.</td>
+<td class="left top padl1 padr1 br">Irregular valve action.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Seat.</td>
+<td class="left top padl1 padr1 br">Scored or warped. Cracked. Covered with scale. Dirt under valve.</td>
+<td class="left top padl1 padr1 br">Gas leak, poor mixture. Poor compression. Valve will not close.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Induction Pipe.</td>
+<td class="left top padl1 padr1 br">Leak at joints. Crack or blowhole.</td>
+<td class="left top padl1 padr1 br">Mixture diluted with excess air.</td>
+<td class="left top padl1 padr1">Stop all leaks.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Inlet Valve.</td>
+<td class="left top padl1 padr1 br">Closes too late. Opens too early.</td>
+<td class="left top padl1 padr1 br">Blowback in carburetor.</td>
+<td class="left top padl1 padr1">Time properly.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Exhaust Valve.</td>
+<td class="left top padl1 padr1 br">Opens too late. Closes too early.</td>
+<td class="left top padl1 padr1 br">Retention of burnt gas dilutes charge.</td>
+<td class="left top padl1 padr1">Time properly.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Stem Guide.</td>
+<td class="left top padl1 padr1 br">Bent or carbonized.</td>
+<td class="left top padl1 padr1 br">Causes valve to stick.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Inlet Valve Stem Guide.<span class='pagenum'><a name="Page_368" id="Page_368">[368]</a></span></td>
+<td class="left top padl1 padr1 br">Worn, stem loose.</td>
+<td class="left top padl1 padr1 br">Air drawn in on suction thins gas.</td>
+<td class="left top padl1 padr1">Bush guide or use new member.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Spring.</td>
+<td class="left top padl1 padr1 br">Weakened or broken.</td>
+<td class="left top padl1 padr1 br">Irregular action.</td>
+<td class="left top padl1 padr1">Use new spring.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Stem Clearance.</td>
+<td class="left top padl1 padr1 br">Too little. Too much.</td>
+<td class="left top padl1 padr1 br">Valve will not shut. Valve opens late, closes early.</td>
+<td class="left top padl1 padr1">Adjust gap <span class="nowrap">.009&#8242;&#8242;</span> inlet,
+<span class="nowrap">.010&#8242;&#8242;</span> exhaust.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Spring Collar Key.</td>
+<td class="left top padl1 padr1 br">Broken.</td>
+<td class="left top padl1 padr1 br">Releases spring.</td>
+<td class="left top padl1 padr1">Replace.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Cam.</td>
+<td class="left top padl1 padr1 br">Worn cam contour. Loose on shaft. Out of time.</td>
+<td class="left top padl1 padr1 br">Valve lift reduced. Does not lift valve. Valves operate at wrong time.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Cam-shaft Bearing.</td>
+<td class="left top padl1 padr1 br">Looseness or wear.</td>
+<td class="left top padl1 padr1 br">Valve timing altered. Valve lift decreased.</td>
+<td class="left top padl1 padr1">Replace.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Cam-shaft.</td>
+<td class="left top padl1 padr1 br">Twisted.</td>
+<td class="left top padl1 padr1 br">Valves out of time.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Cam Fastening.</td>
+<td class="left top padl1 padr1 br">Worn or broken.</td>
+<td class="left top padl1 padr1 br">Valve action irregular.</td>
+<td class="left top padl1 padr1">Replace with new.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Operating Plunger.</td>
+<td class="left top padl1 padr1 br">Loose in guide.</td>
+<td class="left top padl1 padr1 br">Alters valve timing.</td>
+<td class="left top padl1 padr1">Replace with new.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Valve Plunger Guide.</td>
+<td class="left top padl1 padr1 br">Wear in bore. Loose on engine base.</td>
+<td class="left top padl1 padr1 br">Alters valve timing.</td>
+<td class="left top padl1 padr1">Replace or bush. Fasten securely.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Timing Gears.</td>
+<td class="left top padl1 padr1 br">Not properly meshed. Loose on shaft.</td>
+<td class="left top padl1 padr1 br">Valves out of time. Valves do not operate.</td>
+<td class="left top padl1 padr1">Retime properly. Fasten to shaft.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Piston.</td>
+<td class="left top padl1 padr1 br">Walls scored.</td>
+<td class="left top padl1 padr1 br">Leakage of gas.</td>
+<td class="left top padl1 padr1">Smooth up if possible.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Piston Head.</td>
+<td class="left top padl1 padr1 br">Carbon deposits. Crack or blowhole (rare).</td>
+<td class="left top padl1 padr1 br">Cause premature ignition.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr>
+<td class="left top padl1 padr1 br">Piston Rings.</td>
+<td class="left top padl1 padr1 br">No spring. Loose in grooves. Worn or broken.</td>
+<td class="left top padl1 padr1 br">Leakage weakens suction.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+<tr class="bb">
+<td class="left top padl1 padr1 br">Cylinder Wall.</td>
+<td class="left top padl1 padr1 br">Scored by wristpin. Scored by lack of oil.</td>
+<td class="left top padl1 padr1 br">Gas leaks by. Poor suction.</td>
+<td class="left top padl1 padr1">Previously given.</td>
+</tr>
+
+</table>
+
+<p class='pagenum'><a name="Page_369" id="Page_369">[369]</a></p>
+
+<h3><span class="smcap">Ignition System Troubles Only</span></h3>
+
+<h3><i>Motor Will Not Start or Starts Hard</i></h3>
+
+<p style="margin-bottom: 0;">Loose Battery Terminal.<br />
+Magneto Ground Wire Shorted.<br />
+Magneto Defective (No Spark at Plugs).<br />
+Broken Spark Plug Insulation.<br />
+Carbon Deposits or Oil Between Plug Points.<br />
+Spark-Plug Points Too Near Together or Far Apart.<br />
+Wrong Cables to Plugs.<br />
+Short Circuited Secondary Cable.<br />
+Broken Secondary Cable.</p>
+
+<table class="nowrap" style="line-height: 1em; margin: 0 auto 0 0;" summary="Table p. 369-1">
+
+<tr>
+<td class="left padr1">Dry Battery Weak.</td>
+<td class="center symb">&#9131;</td>
+<td rowspan="4" class="left padl1">Battery Systems<br />Only.</td>
+</tr>
+
+<tr>
+<td class="left padr1">Storage Battery Discharged.</td>
+<td class="center symb">&#9132;</td>
+</tr>
+
+<tr>
+<td class="left padr1">Poor Contact at Timer.</td>
+<td class="center symb">&#9134;</td>
+</tr>
+
+<tr>
+<td class="left padr1">Timer Points Dirty.</td>
+<td class="center symb">&#9133;</td>
+</tr>
+
+</table>
+
+<table class="nowrap" style="line-height: 1em; margin: 0 auto 0 0;" summary="Table p. 369-2">
+
+<tr>
+<td class="left padr1">Poor Contact at Switch.</td>
+<td class="center symb">&#9131;</td>
+<td rowspan="6" class="left padl1">Battery and Coil<br />Ignition System Only.</td>
+</tr>
+
+<tr>
+<td class="left padr1">Primary Wires Broken, or Short Circuited.</td>
+<td class="center symb">&#9134;</td>
+</tr>
+
+<tr>
+<td class="left padr1">Battery Grounded in Metal Container.</td>
+<td class="center symb">&#9132;</td>
+</tr>
+
+<tr>
+<td class="left padr1">Battery Connectors Broken or Loose.</td>
+<td class="center symb">&#9134;</td>
+</tr>
+
+<tr>
+<td class="left padr1">Timer Points Out of Adjustment.</td>
+<td class="center symb">&#9134;</td>
+</tr>
+
+<tr>
+<td class="left padr1">Defects in Induction Coil.</td>
+<td class="center symb">&#9133;</td>
+</tr>
+
+</table>
+
+<p style="margin-top: 0;">Ignition Timing Wrong, Spark Too Late or Too Early.<br />
+Defective Platinum Points in Breaker Box (Magneto).<br />
+Points Not Separating.<br />
+Broken Contact Maker Spring.<br />
+No Contact at Secondary Collector Brush.<br />
+Platinum Contact Points Burnt or Pitted.<br />
+Contact Breaker Bell Crank Stuck.<br />
+Fiber Bushing in Bell Crank Swollen.<br />
+Short Circuiting Spring Always in Contact.<br />
+Dirt or Water in Magneto Casing.<br />
+Oil in Contact Breaker.<br />
+Oil Soaked Brush and Collector Ring.<br />
+Distributor Filled with Carbon Particles.</p>
+
+<p class='pagenum'><a name="Page_370" id="Page_370">[370]</a></p>
+
+<h3><i>Motor Stops Without Warning</i></h3>
+
+<p>Broken Magneto Carbon Brush.<br />
+Broken Lead Wire.<br />
+Broken Ground Wire.<br />
+Battery Ignition Systems.<br />
+Water on High Tension Magneto Terminal.<br />
+Main Secondary Cable Burnt Through by Hot Exhaust Pipe (Transformer Coil, Magneto Systems).<br />
+Particle of Carbon Between Spark Plug Points.<br />
+Magneto Short Circuited by Ground Wire.<br />
+Magneto Out of Time, Due to Slipping Drive.<br />
+Water or Oil in Safety Spark Gap (Multi-cylinder Magneto).<br />
+Magneto Contact Breaker or Timer Stuck in Retard Position.<br />
+Worn Fiber Block in Magneto Contact Breaker.<br />
+Binding Fiber Bushing in Contact Breaker Bell Crank.<br />
+Spark Advance Rod or Wire Broken.<br />
+Contact Breaker Parts Stuck.</p>
+
+<h3><i>Motor Runs Irregularly or Misfires</i></h3>
+
+<p>Loose Wiring or Terminals.<br />
+Broken Spark-Plug Insulator.<br />
+Spark-Plug Points Sooted or Oily.<br />
+Wrong Spark Gap at Plug Points.<br />
+Leaking Secondary Cable.<br />
+Prematurely Grounded Primary Wire.<br />
+Batteries Running Down (Battery Ignition only).<br />
+Poor Adjustment of Contact Points at Timer.<br />
+Wire Broken Inside of Insulation.<br />
+Loose Platinum Points in Magneto.<br />
+Weak Contact Spring.<br />
+Broken Collector Brush.<br />
+Dirt in Magneto Distributor Casing or Contact Breaker.<br />
+Worn Fiber Block or Cam Plate in Magneto.<br />
+Worn Cam or Contact Roll in Timer (Battery System only).<span class='pagenum'><a name="Page_371" id="Page_371">[371]</a></span><br />
+Dirty Oil in Timer.<br />
+Sticking Coil Vibrators.<br />
+Coil Vibrator Points Pitted.<br />
+Oil Soaked Magneto Winding.<br />
+Punctured Magneto or Coil Winding.<br />
+Distributor Contact Segments Rough.<br />
+Sulphated Storage Battery Terminals.<br />
+Weak Magnets in Magneto.<br />
+Poor Contact at Magneto Contact Breaker Points.</p>
+
+<h3>DEFECTS IN ELECTRICAL SYSTEM COMPONENTS</h3>
+
+<p>To further simplify the location of electrical system
+faults it is thought desirable to outline the defects that
+can be present in the various parts of the individual devices
+comprising the ignition system. If an airplane
+engine is provided with magneto ignition solely, as most
+engines are at the present time, no attention need be
+paid to such items as storage or dry batteries, timer or
+induction coil. There seems to be some development in
+the direction of battery ignition so it has been considered
+desirable to include components of these systems as well
+as the almost universally used magneto group. Spark-plugs,
+wiring and switches are needed with either system.</p>
+
+<table class="fsize80" summary="Table p. 371-373">
+
+<tr>
+<td colspan="4" class="center" style="line-height: 3em;">SPARK-PLUGS</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left padr1">DEFECT</td>
+<td class="left padr1" style="width: 30%;">TROUBLE CAUSED</td>
+<td class="left padr1" style="width: 30%;">REMEDY</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Insulation cracked.</td>
+<td class="left top padr1">Plug inoperative.</td>
+<td class="left top padr1">New insulation.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Insulation oil soaked.</td>
+<td class="left top padr1">Cylinder misfires.</td>
+<td class="left top padr1">Clean.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Carbon deposits.</td>
+<td class="left top padr1">Short circuited spark.</td>
+<td class="left top padr1">Remove.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Insulator loose.</td>
+<td class="left top padr1">Cylinder misfires.</td>
+<td class="left top padr1">Tighten.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Gasket broken.</td>
+<td class="left top padr1">Gas leaks by.</td>
+<td class="left top padr1">New gasket.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Electrode loose on shell.</td>
+<td class="left top padr1">Cylinder misfires.</td>
+<td class="left top padr1">Tighten.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Wire loose in insulator.</td>
+<td class="left top padr1">Cylinder misfires.</td>
+<td class="left top padr1">Tighten.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Air gap too close.</td>
+<td class="left top padr1">Short circuits spark.</td>
+<td class="left top padr1">Set correctly.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Air gap too wide.</td>
+<td class="left top padr1">Spark will not jump.</td>
+<td class="left top padr1">Set points <span class="nowrap"><sup class="table">1</sup>&#8260;<sub
+class="table">32</sub>&#8242;&#8242;</span> apart.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Loose terminal.</td>
+<td class="left top padr1">Cylinder may misfire.</td>
+<td class="left top padr1">Tighten.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Plug loose in cylinder.</td>
+<td class="left top padr1">Gas leaks.</td>
+<td class="left top padr1">Tighten.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Mica insulation oil soaked.</td>
+<td class="left top padr1">Short circuits spark.</td>
+<td class="left top padr1">Replace.</td>
+</tr>
+
+<tr>
+<td colspan="4" class="center" style="line-height: 3em;">MAGNETO<span class='pagenum' style="font-size: 100%;"><a name="Page_372"
+id="Page_372">[372]</a></span></td>
+</tr>
+
+<tr>
+<td colspan="2" class="left padr1">DEFECT</td>
+<td class="left padr1">TROUBLE CAUSED</td>
+<td class="left padr1">REMEDY</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Dirty oil in distributor.</td>
+<td class="left top padr1">Engine misfires.</td>
+<td class="left top padr1">Clean.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Metal dust in distributor.</td>
+<td class="left top padr1">Engine misfires.</td>
+<td class="left top padr1">Clean.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Brushes not making contact.</td>
+<td class="left top padr1">Current cannot pass.</td>
+<td class="left top padr1">Strengthen spring.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Distributor segments worn.</td>
+<td class="left top padr1">Engine misfires.</td>
+<td class="left top padr1">Secure even bearing.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Collecting brush broken.</td>
+<td class="left top padr1">Engine misfires.</td>
+<td class="left top padr1">New brush.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Distributing brush broken.</td>
+<td class="left top padr1">Engine misfires.</td>
+<td class="left top padr1">New brush.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Oil soaked winding.</td>
+<td class="left top padr1">Engine misfires.</td>
+<td class="left top padr1">Clean.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Magnets loose on pole pieces.</td>
+<td class="left top padr1">Engine misfires.</td>
+<td class="left top padr1">Tighten screws.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Armature rubs.</td>
+<td class="left top padr1">Engine misfires.</td>
+<td class="left top padr1">Repair bearings.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Bearings worn.</td>
+<td class="left top padr1">Noisy.</td>
+<td class="left top padr1">Replace.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Magnets weak.</td>
+<td class="left top padr1">Weak spark.</td>
+<td class="left top padr1">Recharge.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Contact breaker points pitted.</td>
+<td class="left top padr1">Engine misfires.</td>
+<td class="left top padr1">Clean.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Breaker points out of adjustment.</td>
+<td class="left top padr1">Engine misfires.</td>
+<td class="left top padr1">Reset.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Defective winding (rare).</td>
+<td class="left top padr1">No spark.</td>
+<td class="left top padr1">Replace.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Punctured condenser (rare).</td>
+<td class="left top padr1">Weak or no spark.</td>
+<td class="left top padr1">Replace.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Driving gear loose.</td>
+<td class="left top padr1">Noise.</td>
+<td class="left top padr1">Tighten.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Magneto armature out of time.</td>
+<td class="left top padr1">Spark will not fire charge.</td>
+<td class="left top padr1">Retime.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Magneto loose on base.</td>
+<td class="left top padr1">Misfiring and noisy.</td>
+<td class="left top padr1">Tighten.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Contact breaker cam worn.</td>
+<td class="left top padr1">Misfiring.</td>
+<td class="left top padr1">Replace.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Fibre shoe or rolls worn (Bosch).</td>
+<td class="left top padr1">Misfiring.</td>
+<td class="left top padr1">Replace.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Fibre bushing binding in contact lever (Bosch).</td>
+<td class="left top padr1">Misfiring.</td>
+<td class="left top padr1">Ream slightly.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Contact lever return spring broken.</td>
+<td class="left top padr1">No spark.</td>
+<td class="left top padr1">Replace.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Contact lever return spring weak.</td>
+<td class="left top padr1">Misfiring.</td>
+<td class="left top padr1">Replace.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Ground wire grounded.</td>
+<td class="left top padr1">No spark.</td>
+<td class="left top padr1">Insulate.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Ground wire broken.</td>
+<td class="left top padr1">Engine will not stop.</td>
+<td class="left top padr1">Connect up.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Safety spark gap dirty.</td>
+<td class="left top padr1">No spark.</td>
+<td class="left top padr1">Clean.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Fused metal in spark gap.</td>
+<td class="left top padr1">No spark.</td>
+<td class="left top padr1">Remove.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Safety spark gap points too close.</td>
+<td class="left top padr1">Misfiring.</td>
+<td class="left top padr1">Set properly.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Loose distributor terminals.</td>
+<td class="left top padr1">Misfiring.</td>
+<td class="left top padr1">Tighten.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Contact breaker sticks.</td>
+<td class="left top padr1">No spark control.</td>
+<td class="left top padr1">Remove and clean bearings.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Magneto switch short-circuited.</td>
+<td class="left top padr1">No spark.</td>
+<td class="left top padr1">Insulate.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Magneto switch open circuit.</td>
+<td class="left top padr1">No engine stop.</td>
+<td class="left top padr1">Restore contact.</td>
+</tr>
+
+<tr>
+<td colspan="4" class="center" style="line-height: 3em;">STORAGE BATTERY</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left padr1">DEFECT</td>
+<td class="left padr1">TROUBLE CAUSED</td>
+<td class="left padr1">REMEDY</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Electrolyte low.</td>
+<td class="left top padr1">Weak current.</td>
+<td class="left top padr1">Replenish with distilled water.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Loose terminals.</td>
+<td class="left top padr1">Misfiring.</td>
+<td class="left top padr1">Tighten.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Sulphated terminals.</td>
+<td class="left top padr1">Misfiring.</td>
+<td class="left top padr1">Clean thoroughly and coat with vaseline.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Battery discharged.</td>
+<td class="left top padr1">Misfiring or no spark.</td>
+<td class="left top padr1">New charge.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Electrolyte weak.</td>
+<td class="left top padr1">Weak current.</td>
+<td class="left top padr1">Bring to proper specific gravity.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Plates sulphated.</td>
+<td class="left top padr1">Poor capacity.</td>
+<td class="left top padr1">Special slow charge.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Sediment or mud in bottom.</td>
+<td class="left top padr1">Weak current.</td>
+<td class="left top padr1">Clean out.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Active material loose in grids.</td>
+<td class="left top padr1">Poor capacity.</td>
+<td class="left top padr1">New plates.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Moisture or acid on top of cells.</td>
+<td class="left top padr1">Shorts terminals.</td>
+<td class="left top padr1">Remove.<span class='pagenum' style="font-size: 100%;"><a name="Page_373" id="Page_373">[373]</a></span></td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Plugged vent cap.</td>
+<td class="left top padr1">Buckles cell jars.</td>
+<td class="left top padr1">Make vent hole.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Cracked vent cap.</td>
+<td class="left top padr1">Acid spills out.</td>
+<td class="left top padr1">New cap.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Cracked cell jar.</td>
+<td class="left top padr1">Electrolyte runs out.</td>
+<td class="left top padr1">New jar.</td>
+</tr>
+
+<tr>
+<td colspan="4" class="center" style="line-height: 3em;">DRY CELL BATTERY</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left padr1">DEFECT</td>
+<td class="left padr1">TROUBLE CAUSED</td>
+<td class="left padr1">REMEDY</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Broken wires.</td>
+<td class="left top padr1">No current.</td>
+<td class="left top padr1">New wires.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Loose terminals.</td>
+<td class="left top padr1">Misfiring.</td>
+<td class="left top padr1">Tighten.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Weak cell (7 amperes or less).</td>
+<td class="left top padr1">Misfiring.</td>
+<td class="left top padr1">New cells.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Cells in contact.</td>
+<td class="left top padr1">Short circuit.</td>
+<td class="left top padr1">Separate and insulate.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Water in battery box.</td>
+<td class="left top padr1">Short circuit.</td>
+<td class="left top padr1">Dry out.</td>
+</tr>
+
+<tr>
+<td colspan="4" class="center" style="line-height: 3em;">TIMER</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left padr1">DEFECT</td>
+<td class="left padr1">TROUBLE CAUSED</td>
+<td class="left padr1">REMEDY</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Contact segments worn or pitted.</td>
+<td class="left top padr1">Misfiring.</td>
+<td class="left top padr1">Grind down smooth.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Platinum points pitted.</td>
+<td class="left top padr1">Misfiring.</td>
+<td class="left top padr1">Smooth with oil stone.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Dirty oil or metal dust in interior.</td>
+<td class="left top padr1">Misfiring.</td>
+<td class="left top padr1">Clean out.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Worn bearing.</td>
+<td class="left top padr1">Misfiring.</td>
+<td class="left top padr1">Replace.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Loose terminals.</td>
+<td class="left top padr1">Misfiring.</td>
+<td class="left top padr1">Tighten.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Worn revolving contact brush.</td>
+<td class="left top padr1">Misfiring.</td>
+<td class="left top padr1">Replace.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Out of time.</td>
+<td class="left top padr1">Irregular spark.</td>
+<td class="left top padr1">Reset.</td>
+</tr>
+
+<tr>
+<td colspan="4" class="center" style="line-height: 3em;">INDUCTION COIL</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left padr1">DEFECT</td>
+<td class="left padr1">TROUBLE CAUSED</td>
+<td class="left padr1">REMEDY</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Loose terminals.</td>
+<td class="left top padr1">Misfiring.</td>
+<td class="left top padr1">Tighten.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Broken connections.</td>
+<td class="left top padr1">No spark.</td>
+<td class="left top padr1">Make new joints.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Vibrators out of adjustment.</td>
+<td class="left top padr1">Misfiring.</td>
+<td class="left top padr1">Readjust.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Vibrator points pitted.</td>
+<td class="left top padr1">Misfiring.</td>
+<td class="left top padr1">Clean.</td>
+</tr>
+
+<tr>
+<td class="left top padr1">Defective condenser</td>
+<td rowspan="2" class="left"><span class="fsize150">}</span> rare.</td>
+<td rowspan="2" class="left padr1">No spark.</td>
+<td rowspan="2" class="left padr1">Send to maker for repairs.</td>
+</tr>
+
+<tr>
+<td class="left top padr1">Defective winding</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Poor contact at switch.</td>
+<td class="left top padr1">Misfiring.</td>
+<td class="left top padr1">Tighten.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Broken internal wiring.</td>
+<td class="left top padr1">No spark.</td>
+<td class="left top padr1">Replace.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Poor coil unit.</td>
+<td class="left top padr1">One cylinder affected.</td>
+<td class="left top padr1">Replace.</td>
+</tr>
+
+<tr>
+<td colspan="4" class="center" style="line-height: 3em;">WIRING</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left padr1">DEFECT</td>
+<td class="left padr1">TROUBLE CAUSED</td>
+<td class="left padr1">REMEDY</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Loose terminals anywhere.</td>
+<td class="left top padr1">Misfiring.</td>
+<td class="left top padr1">Tighten.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Broken plug wire.</td>
+<td class="left top padr1">One cylinder will not fire.</td>
+<td class="left top padr1">Replace.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Broken timer wire.</td>
+<td class="left top padr1">One coil will not buzz.</td>
+<td class="left top padr1">Replace.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Broken main battery wire.</td>
+<td rowspan="2" class="left padl1"><span class="fsize150">}</span> No spark.</td>
+<td rowspan="2" class="left padr1">Replace.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Broken battery ground wire.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Broken magneto ground wire.</td>
+<td class="left top padr1">Engine will not stop.</td>
+<td class="left top padr1">Replace.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Chafed insulation anywhere.</td>
+<td rowspan="2" class="left padl1"><span class="fsize150">}</span> Misfiring.</td>
+<td rowspan="2" class="left padr1">Insulate.</td>
+</tr>
+
+<tr>
+<td colspan="2" class="left top padr1">Short circuit anywhere.</td>
+</tr>
+
+</table>
+
+<p class='pagenum'><a name="Page_374" id="Page_374">[374]</a></p>
+
+<h3><span class="smcap">Carburetion System Faults Summarized</span></h3>
+
+<h3><i>Motor Starts Hard or Will Not Start</i></h3>
+
+<p>No Gasoline in Tank.<br />
+No Gasoline in Carburetor Float Chamber.<br />
+Tank Shut-Off Closed.<br />
+Clogged Filter Screen.<br />
+Fuel Supply Pipe Clogged.<br />
+Gasoline Level Too Low.<br />
+Gasoline Level Too High (Flooding).<br />
+Bent or Stuck Float Lever.<br />
+Loose or Defective Inlet Manifold.<br />
+Not Enough Gasoline at Jet.<br />
+Cylinders Flooded with Gas.<br />
+Fuel Soaked Cork Float (Causes Flooding).<br />
+Water in Carburetor Spray Nozzle.<br />
+Dirt in Float Chamber.<br />
+Gas Mixture Too Lean.<br />
+Carburetor Frozen (Winter Only).</p>
+
+<h3><i>Motor Stops In Flight</i></h3>
+
+<p>Gasoline Shut-Off Valve Jarred Closed.<br />
+Gasoline Supply Pipe Clogged.<br />
+No Gasoline in Tank.<br />
+Spray Nozzle Stopped Up.<br />
+Water in Spray Nozzle.<br />
+Particles of Carbon Between Spark-Plug Points.<br />
+Magneto Short Circuited by Ground in Wire.<br />
+Air Lock in Gasoline Pipe.<br />
+Broken Air Line or Leaky Tank (Pressure Feed System Only).<br />
+Fuel Supply Pipe Partially Clogged.<br />
+Air Vent in Tank Filler Cap Stopped Up (Gravity and Vacuum Feed System).<br />
+Float Needle Valve Stuck.<br />
+Water or Dirt in Spray Nozzle.<br />
+Mixture Adjusting Needle Jarred Loose (Rotary Motors Only).</p>
+
+<p class='pagenum'><a name="Page_375" id="Page_375">[375]</a></p>
+
+<h3><i>Motor Races, Will Not Throttle Down</i></h3>
+
+<p>Air Leak in Inlet Piping.<br />
+Air Leak Through Inlet Valve Guides.<br />
+Control Rods Broken.<br />
+Defective Induction Pipe Joints.<br />
+Leaky Carburetor Flange Packing.<br />
+Throttle Not Closing.<br />
+Poor Slow Speed Adjustment (Zenith Carburetor).</p>
+
+<h3><i>Motor Misfires</i></h3>
+
+<p>Carburetor Float Chamber Getting Dry.<br />
+Water or Dirt in Gasoline.<br />
+Poor Gasoline Adjustment (Rotary Motors).<br />
+Not Enough Gasoline in Float Chamber.<br />
+Too Much Gasoline, Carburetor Flooding.<br />
+Incorrect Jet or Choke (Zenith Carburetor).<br />
+Broken Cylinder Head Packing Between Cylinders.</p>
+
+<h3><i>Noisy Operation</i></h3>
+
+<p>Popping or Blowing Back in Carburetor.<br />
+Incorrectly Timed Inlet Valves.<br />
+Inlet Valve Not Seating.<br />
+Defective Inlet Valve Spring.<br />
+Dirt Under Inlet Valve Seat.<br />
+Not Enough Gasoline (Open Needle Valve).<br />
+Muffler or Manifold Explosions.<br />
+Mixture Not Exploding Regularly.<br />
+Exhaust Valve Sticking.<br />
+Dirt Under Exhaust Valve Seat.</p>
+
+<hr class="c25" />
+<p class='pagenum'><a name="Page_376" id="Page_376">[376]</a></p>
+
+<h2><a name="ChXI" id="ChXI"></a>CHAPTER XI</h2>
+
+<div class="chapsec"><p><a href="#SecXI_1">Tools for Adjusting and Erecting</a>&mdash;<a href="#SecXI_2">Forms of Wrenches</a>&mdash;<a
+href="#SecXI_3">Use and Care of Files</a>&mdash;<a href="#SecXI_4">Split Pin Removal and Installation</a>&mdash;<a href="#SecXI_5">Complete
+Chisel Set</a>&mdash;<a href="#SecXI_6">Drilling Machines</a>&mdash;<a href="#SecXI_7">Drills, Reamers, Taps and Dies</a>&mdash;<a
+href="#SecXI_8">Measuring Tools</a>&mdash;<a href="#SecXI_9">Micrometer Calipers and Their Use</a>&mdash;<a href="#SecXI_10">Typical Tool
+Outfits</a>&mdash;<a href="#SecXI_11">Special Hall-Scott Tools</a>&mdash;<a href="#SecXI_12">Overhauling Airplane Engines</a>&mdash;<a
+href="#SecXI_13">Taking Engine Down</a>&mdash;<a href="#SecXI_14">Defects in Cylinders</a>&mdash;<a href="#SecXI_15">Carbon Deposits,
+Cause and Prevention</a>&mdash;<a href="#SecXI_16">Use of Carbon Scrapers</a>&mdash;<a href="#SecXI_17">Burning Out Carbon with
+Oxygen</a>&mdash;<a href="#SecXI_18">Repairing Scored Cylinders</a>&mdash;<a href="#SecXI_19">Valve Removal and Inspection</a>&mdash;<a
+href="#SecXI_20">Reseating and Truing Valves</a>&mdash;<a href="#SecXI_21">Valve Grinding Processes</a>&mdash;<a
+href="#SecXI_22">Depreciation in Valve Operating System</a>&mdash;<a href="#SecXI_23">Piston Troubles</a>&mdash;<a href="#SecXI_24">Piston
+Ring Manipulation</a>&mdash;<a href="#SecXI_25">Fitting Piston Rings</a>&mdash;<a href="#SecXI_26">Wrist-Pin Wear</a>&mdash;<a
+href="#SecXI_27">Inspection and Refitting of Engine Bearings</a>&mdash;<a href="#SecXI_28">Scraping Brasses to Fit</a>&mdash;<a
+href="#SecXI_29">Fitting Connecting Rods</a>&mdash;<a href="#SecXI_30">Testing for Bearing Parallelism</a>&mdash;<a
+href="#SecXI_31">Cam-Shafts and Timing Gears</a>&mdash;<a href="#SecXI_32">Precautions in Reassembling Parts</a>.</p></div>
+
+<h3><a name="SecXI_1" id="SecXI_1"></a>TOOLS FOR ADJUSTING AND ERECTING</h3>
+
+<p>A very complete outfit of small tools, some of which
+are furnished as part of the tool equipment of various
+engines are shown in group at <a href="#Fig163">Fig. 163</a>. This group includes
+all of the tools necessary to complete a very practical
+kit and it is not unusual for the mechanic who is
+continually dismantling and erecting engines to possess
+even a larger assortment than indicated. The small bench
+vise provided is a useful auxiliary that can be clamped
+to any convenient bench or table or even fuselage longeron
+in an emergency and should have jaws at least three
+inches wide and capable of opening four or five inches.
+It is especially useful in that it will save trips to the
+bench vises, as it has adequate capacity to handle practically
+any of the small parts that need to be worked on
+when making repairs. A blow torch, tinner&#8217;s snips and
+soldering copper are very useful in sheet metal work and
+in making any repairs requiring the use of solder. The
+torch can be used in any operation requiring a source of<span class='pagenum'><a name="Page_378"
+id="Page_378">[378]</a></span><span class='pagenum'><a name="Page_377" id="Page_377"></a></span>
+heat. The large box wrench shown under the vise is used
+for removing large special nuts and sometimes has one
+end of the proper size to fit the valve chamber cap. The
+piston ring removers are easily made from thin strips of
+sheet metal securely brazed or soldered to a light wire
+handle. These are used in sets of three for removing
+and applying piston rings in a manner to be indicated.
+The uses of the wrenches, screw drivers, and pliers shown
+are known to all and the variety outlined should be sufficient
+for all ordinary work of restoration. The wrench
+equipment is very complete, including a set of open end
+S-wrenches to fit all standard bolts, a spanner wrench,
+socket or box wrenches for bolts that are inaccessible with
+the ordinary type, adjustable end wrenches, a thin monkey
+wrench of medium size, a bicycle wrench for handling
+small nuts and bolts, a Stillson wrench for pipe and a
+large adjustable monkey wrench for the stubborn fastenings
+of large size.</p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig163" id="Fig163"></a>
+<img src="images/illo372.png" alt="Fig. 163" width="350" height="604" />
+<p class="caption">Fig. 163.&mdash;Practical Hand Tools Useful in Dismantling and Repairing
+Airplane Engines.</p></div>
+
+<p>Four different types of pliers are shown, one being a
+parallel jaw type with size cutting attachment, while the
+other illustrated near it is a combination parallel jaw type
+adapted for use on round work as well as in handling
+flat stock. The most popular form of pliers is the combination
+pattern shown beneath the socket wrench set.
+This is made of substantial drop forgings having a hinged
+joint that can be set so that a very wide opening at the
+jaws is possible. These can be used on round work and
+for wire cutting as well as for handling flat work. Round
+nose pliers are very useful also.</p>
+
+<p>A very complete set of files, including square, half
+round, mill, flat bastard, three-cornered and rat tail are
+also necessary. A hacksaw frame and a number of saws,
+some with fine teeth for tubing and others with coarser
+teeth for bar or solid stock will be found almost indispensable.
+A complete punch and chisel set should be provided,
+samples of which are shown in the group while the
+complete outfit is outlined in another illustration. A
+number of different forms and sizes of chisels are necessary,<span class='pagenum'><a name="Page_379" id="Page_379">[379]</a></span>
+as one type is not suitable for all classes of work.
+The adjustable end wrenches can be used in many places
+where a monkey wrench cannot be fitted and where it
+will be difficult to use a wrench having a fixed opening.
+The Stillson pipe wrench is useful in turning studs, round
+rods, and pipes that cannot be turned by any other means.
+A complete shop kit must necessarily include various sizes
+for Stillson and monkey wrenches, as no one size can be
+expected to handle the wide range of work the engine
+repairman must cope with. Three sizes of each form of
+wrench can be used, one, a 6 inch, is as small as is needed
+while, a 12 inch tool will handle almost any piece of pipe
+or nut used in engine construction.</p>
+
+<p>Three or four sizes of hammers should be provided,
+according to individual requirement, these being small
+riveting, medium and heavyweight machinist&#8217;s hammers.
+A very practical tool of this nature for the repair shop
+can be used as a hammer, screw driver or pry iron. It is
+known as the &#8220;Spartan&#8221; hammer and is a tool steel drop
+forging in one piece having the working surfaces properly
+hardened and tempered while the metal is distributed so
+as to give a good balance to the head and a comfortable
+grip to the handle. The hammer head provides a positive
+and comfortable T-handle when the tool is used as
+a screw driver or &#8220;tommy&#8221; bar. Machinist&#8217;s hammers
+are provided with three types of heads, these being of
+various weights. The form most commonly used is
+termed the &#8220;ball pein&#8221; on account of the shape of the
+portion used for riveting. The straight pein is just the
+same as the cross pein, except that in the latter the
+straight portion is at right angles to the hammer handle,
+while in the former it is parallel to that member.</p>
+
+<h3><a name="SecXI_2" id="SecXI_2"></a>FORMS OF WRENCHES</h3>
+
+<p>Wrenches have been made in infinite variety and there
+are a score or more patterns of different types of adjustable
+socket and off-set wrenches. The various wrench<span class='pagenum'><a name="Page_380" id="Page_380">[380]</a></span>
+types that differ from the more conventional monkey
+wrenches or those of the Stillson pattern are shown at
+<a href="#Fig164">Fig. 164</a>. The &#8220;perfect handle&#8221; is a drop forged open
+end form provided with a wooden handle similar to that
+used on a monkey wrench in order to provide a better
+grip for the hand. The &#8220;Saxon&#8221; wrench is a double
+alligator form, so called because the jaws are in the form
+of a V-groove having one side of the V plain, while the
+other is serrated in order to secure a tight grip on round
+objects. In the form shown, two jaws of varying sizes
+are provided, one for large work, the other to handle the
+smaller rods. One of the novel features in connection
+with this wrench is the provision of a triple die block in
+the centre of the handle which is provided with three
+most commonly used of the standard threads including
+<sup>5</sup>&#8260;<sub>16</sub>-inch-18, <sup>3</sup>&#8260;<sub>8</sub>-inch-16, and
+<sup>1</sup>&#8260;<sub>2</sub>-inch-13. This is useful in
+cleaning up burred threads on bolts before they are
+replaced, as burring is unavoidable if it has been necessary
+to drive them out with a hammer. The &#8220;Lakeside&#8221;
+wrench has an adjustable pawl engaging with one of a
+series of notches by which the opening may be held in
+any desired position.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig164" id="Fig164"></a>
+<img src="images/illo375.png" alt="Fig. 164" width="500" height="287" />
+<p class="caption">Fig. 164.&mdash;Wrenches are Offered in Many Forms.</p></div>
+
+<p>Ever since the socket wrench was invented it has been<span class='pagenum'><a name="Page_381" id="Page_381">[381]</a></span>
+a popular form because it can be used in many places
+where the ordinary open end or monkey wrench cannot
+be applied owing to lack of room for the head of the
+wrench. A typical set which has been made to fit in a very
+small space is shown at D. It consists of a handle, which
+is nickel-plated and highly polished, a long extension bar,
+a universal joint and a number of case hardened cold
+drawn steel sockets to fit all commonly used standard nuts
+and bolt heads. Two screw-driver bits, one small and the
+other large to fit the handle, and a long socket to fit spark-plugs
+are also included in this outfit. The universal joint
+permits one to remove nuts in a position that would be
+inaccessible to any other form of wrench, as it enables
+the socket to be turned even if the handle is at one side
+of an intervening obstruction.</p>
+
+<p>The &#8220;Pick-up&#8221; wrench, shown at E, is used for spark-plugs
+and the upper end of the socket is provided with a
+series of grooves into which a suitable blade carried by
+the handle can be dropped. The handle is pivoted to the
+top of the socket in such a way that the blades may be
+picked up out of the grooves by lifting on the end of the
+handle and dropped in again when the handle is swung
+around to the proper point to get another hold on the
+socket. The &#8220;Miller&#8221; wrench shown at F, is a combination
+socket and open end type, made especially for use
+with spark-plugs. Both the open end and the socket are
+convenient. The &#8220;Handy&#8221; set shown at G, consists of a
+number of thin stamped wrenches of steel held together
+in a group by a simple clamp fitting, which enables either
+end of any one of the four double wrenches to be brought
+into play according to the size of the nut to be turned.
+The &#8220;Cronk&#8221; wrench shown at H, is a simple stamping
+having an alligator opening at one end and a stepped
+opening capable of handling four different sizes of standard
+nuts or bolt heads at the other. Such wrenches are
+very cheap and are worth many times their small cost,
+especially for fitting nuts where there is not sufficient
+room to admit the more conventional pattern. The<span class='pagenum'><a name="Page_382" id="Page_382">[382]</a></span>
+&#8220;Starrett&#8221; wrench set, which is shown at I, consists of
+a ratchet handle together with an extension bar and universal
+joint, a spark-plug socket, a drilling attachment
+which takes standard square shank drills from <sup>1</sup>&#8260;<sub>8</sub>-inch to
+<sup>1</sup>&#8260;<sub>2</sub>-inch in diameter, a double ended screw-driver bit and
+several adjustments to go with the drilling attachment.
+Twenty-eight assorted cold drawn steel sockets similar in
+design to those shown at D, to fit all standard sizes of
+square and hexagonal headed nuts are also included. The
+reversible ratchet handle, which may be slipped over the
+extension bar or the universal joint and which is also
+adapted to take the squared end of any one of the sockets
+is exceptionally useful in permitting, as it does, the instant
+release of pressure when it is desired to swing the
+handle back to get another hold on the nut. The socket
+wrench sets are usually supplied in hard wood cases or
+in leather bags so that they may be kept together and
+protected against loss or damage. With a properly selected
+socket wrench set, either of the ratchet handle or
+T-handle form, any nut on the engine may be reached and
+end wrenches will not be necessary.</p>
+
+<h3><a name="SecXI_3" id="SecXI_3"></a>USE AND CARE OF FILES</h3>
+
+<p>Mention has been previously made of the importance
+of providing a complete set of files and suitable handles.
+These should be in various grades or degrees of fineness
+and three of each kind should be provided. In the flat
+and half round files three grades are necessary, one with
+coarse teeth for roughing, and others with medium and
+fine teeth for the finishing cuts. The round or rat tail
+file is necessary in filing out small holes, the half round
+for finishing the interior of large ones. Half round files
+are also well adapted for finishing surfaces of peculiar
+contour, such as the inside of bearing boxes, connecting
+rod and main bearing caps, etc. Square files are useful
+in finishing keyways or cleaning out burred splines, while
+the triangular section or three-cornered file is of value in<span class='pagenum'><a name="Page_383" id="Page_383">[383]</a></span>
+cleaning out burred threads and sharp corners. Flat files
+are used on all plane surfaces.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig165" id="Fig165"></a>
+<img src="images/illo378.png" alt="Fig. 165" width="400" height="494" />
+<p class="caption">Fig. 165.&mdash;Illustrating Use and Care of Files.</p></div>
+
+<p>The file brush shown at <a href="#Fig165">Fig. 165</a>, A, consists of a large
+number of wire bristles attached to a substantial wood
+back having a handle of convenient form so that the
+bristles may be drawn through the interstices between
+the teeth of the file to remove dirt and grease. If the<span class='pagenum'><a name="Page_384" id="Page_384">[384]</a></span>
+teeth are filled with pieces of soft metal, such as solder
+or babbitt, it may be necessary to remove this accumulation
+with a piece of sheet metal as indicated at <a href="#Fig165">Fig.
+165</a>, B. The method of holding a file for working on
+plain surfaces when it is fitted with the regular form of
+wooden handle is shown at C, while two types of handles
+enabling the mechanic to use the flat file on plain surfaces
+of such size that the handle type indicated at C,
+could not be used on account of interfering with the surface
+finished are shown at D. The method of using a
+file when surfaces are finished by draw filing is shown at
+E. This differs from the usual method of filing and is
+only used when surfaces are to be polished and very little
+metal removed.</p>
+
+<h3><a name="SecXI_4" id="SecXI_4"></a>SPLIT PIN REMOVAL AND INSERTION</h3>
+
+<p>One of the most widely used of the locking means to
+prevent nuts or bolts from becoming loose is the simple
+split pin, sometimes called a &#8220;cotter pin.&#8221; These can be
+handled very easily if the special pliers shown at <a href="#Fig166">Fig.
+166</a>, A, are used. They have a curved jaw that permits
+of grasping the pin firmly and inserting it in the hole
+ready to receive it. It is not easy to insert these split
+pins by other means because the ends are usually spread
+out and it is hard to enter the pin in the hole. With the
+cotter pin pliers the ends may be brought close together
+and as the plier jaws are small the pin may be easily
+pushed in place. Another use of this plier, also indicated,
+is to bend over the ends of the split pin in order to prevent
+it from falling out. To remove these pins a simple
+curved lever, as shown at <a href="#Fig166">Fig. 166</a>, B, is used. This has
+one end tapering to a point and is intended to be inserted
+in the eye of the cotter pin, the purchase offered
+by the handle permitting of ready removal of the pin
+after the ends have been closed by the cotter pin pliers.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig166" id="Fig166"></a>
+<img src="images/illo380.jpg" alt="Fig. 166" width="450" height="413" />
+<p class="caption">Fig. 166.&mdash;Outlining Use of Cotter Pin Pliers, Spring Winder, and Showing
+Practical Outfit of Chisels.</p></div>
+
+<p class='pagenum'><a name="Page_385" id="Page_385">[385]</a></p>
+
+<h3><a name="SecXI_5" id="SecXI_5"></a>COMPLETE CHISEL SET</h3>
+
+<p>A complete chisel set suitable for repair shop use is
+also shown at <a href="#Fig166">Fig. 166</a>. The type at C is known as a
+&#8220;cape&#8221; chisel and has a narrow cutting point and is intended
+to chip keyways, remove metal out of corners and
+for all other work where the broad cutting edge chisel,
+shown at D, cannot be used. The form with the wide
+cutting edge is used in chipping, cutting sheet metal, etc.
+At E, a round nose chisel used in making oil ways is outlined,
+while a similar tool having a pointed cutting edge
+and often used for the same purpose is shown at F. The
+centre punch depicted at G, is very useful for marking
+parts either for identification or for drilling. In addition<span class='pagenum'><a name="Page_386" id="Page_386">[386]</a></span>
+to the chisels shown, a number of solid punches or drifts
+resembling very much that shown at E, except that the
+point is blunt should be provided to drive out taper pins,
+bolts, rivets, and other fastenings of this nature. These
+should be provided in the common sizes. A complete set
+of real value would start at <sup>1</sup>&#8260;<sub>8</sub>-inch and increase by increments
+of <sup>1</sup>&#8260;<sub>32</sub>-inch up to <sup>1</sup>&#8260;<sub>2</sub>-inch. A simple spring winder
+is shown at <a href="#Fig166">Fig. 166</a>, H, this making it possible for the
+repairman to wind coil springs, either on the lathe or in
+the vise. It will handle a number of different sizes of
+wire and can be set to space the coils as desired.</p>
+
+<h3><a name="SecXI_6" id="SecXI_6"></a>DRILLING MACHINES</h3>
+
+<p>Drilling machines may be of two kinds, hand or power
+operated. For drilling small holes in metal it is necessary
+to run the drill fast, therefore the drill chuck is
+usually driven by gearing in order to produce high drill
+speed without turning the handle too fast. A small hand
+drill is shown at <a href="#Fig167">Fig. 167</a>, A. As will be observed, the
+chuck spindle is driven by a small bevel pinion, which in
+turn, is operated by a large bevel gear turned by a crank.
+The gear ratio is such that one turn of the handle will
+turn the chuck five or six revolutions. A drill of this
+design is not suited for drills any larger than one-quarter
+inch. For use with drills ranging from one-eighth to
+three-eighths, or even half-inch the hand drill presses
+shown at C and D are used. These have a pad at the
+upper end by which pressure may be exerted with the
+chest in order to feed the drill into the work, and for
+this reason they are termed &#8220;breast drills.&#8221; The form
+at C has compound gearing, the drill chuck being driven
+by the usual form of bevel pinion in mesh with a larger
+bevel gear at one end of a countershaft. A small helical
+spur pinion at the other end of this countershaft receives
+its motion from a larger gear turned by the hand crank.
+This arrangement of gearing permits of high spindle
+speed without the use of large gears, as would be necessary<span class='pagenum'><a name="Page_387" id="Page_387">[387]</a></span>
+if but two were used. The form at D gives two
+speeds, one for use with small drills is obtained by engaging
+the lower bevel pinion with the chuck spindle and
+driving it by the large ring gear. The slow speed is obtained
+by shifting the clutch so that the top bevel pinion
+drives the drill chuck. As this meshes with a gear but
+slightly larger in diameter, a slow speed of the drill
+chuck is possible. Breast drills are provided with a<span class='pagenum'><a name="Page_388" id="Page_388">[388]</a></span>
+handle screwed into the side of the frame, these are used
+to steady the drill press. For drilling extremely large
+holes which are beyond the capacity of the usual form
+of drill press the ratchet form shown at B, may be used
+or the bit brace outlined at E. The drills used with either
+of these have square shanks, whereas those used in the
+drill presses have round shanks. The bit brace is also
+used widely in wood work and the form shown is provided
+with a ratchet by which the bit chuck may be turned
+through only a portion of a revolution in either direction
+if desired.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig167" id="Fig167"></a>
+<img src="images/illo382.jpg" alt="Fig. 167" width="400" height="475" />
+<p class="caption">Fig. 167.&mdash;Forms of Hand Operated Drilling Machines.</p></div>
+
+<h3><a name="SecXI_7" id="SecXI_7"></a>DRILLS, REAMERS, TAPS AND DIES</h3>
+
+<p>In addition to the larger machine tools and the simple
+hand tools previously described, an essential item of equipment
+of any engine or plane repair shop, even in cases
+where the ordinary machine tools are not provided, is a
+complete outfit of drills, reamers, and threading tools.
+Drills are of two general classes, the flat and the twist
+drills. The flat drill has an angle between cutting edges
+of about 110 degrees and is usually made from special
+steel commercially known as drill rod.</p>
+
+<p>A flat drill cannot be fed into the work very fast because
+it removes metal by a scraping, rather than a
+cutting process. The twist drill in its simplest form is
+cylindrical throughout the entire length and has spiral
+flutes which are ground off at the end to form the cutting
+lip and which also serve to carry the metal chips out of
+the holes. The simplest form of twist drill used is shown
+at <a href="#Fig168">Fig. 168</a>, C, and is known as a &#8220;chuck&#8221; drill, because
+it must be placed in a suitable chuck to turn it. A twist
+drill removes metal by cutting and it is not necessary to
+use a heavy feed as the drill will tend to feed itself into
+the work.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig168" id="Fig168"></a>
+<img src="images/illo384.png" alt="Fig. 168" width="450" height="392" />
+<p class="caption">Fig. 168.&mdash;Forms of Drills Used in Hand and Power Drilling Machines.</p></div>
+
+<p>Larger drills than <sup>3</sup>&#8260;<sub>4</sub>-inch are usually made with a
+tapered shank as shown at <a href="#Fig168">Fig. 168</a>, B. At the end of
+the taper a tongue is formed which engages with a suitable
+opening in the collet, as the piece used to support<span class='pagenum'><a name="Page_389" id="Page_389">[389]</a></span>
+the drill is called. The object of this tongue is to relieve
+the tapered portion of the drill from the stress of driving
+by frictional contact alone, as this would not turn the
+drill positively and the resulting slippage would wear the
+socket, this depreciation changing the taper and making
+it unfit for other drills. The tongue is usually proportioned
+so it is adequate to drive the drill under any condition.
+A small keyway is provided in the collet into which
+a tapering key of flat stock may be driven against the
+end of the tongue to drive the drill from the spindle. A
+standard taper for drill shanks generally accepted by the
+machine trade is known as the Morse and is a taper of
+five-eighths of an inch to the foot. The Brown and Sharp
+form tapers six-tenths of an inch to the foot. Care must
+be taken, therefore, when purchasing drills and collets,<span class='pagenum'><a name="Page_390" id="Page_390">[390]</a></span>
+to make sure that the tapers coincide, as no attempt
+should be made to run a Morse taper in a Brown and
+Sharp collet, or vice versa.</p>
+
+<p>Sometimes cylindrical drills have straight flutes, as
+outlined at <a href="#Fig168">Fig. 168</a>, A. Such drills are used with soft
+metals and are of value when the drill is to pass entirely
+through the work. The trouble with a drill with spiral
+flutes is that it will tend to draw itself through as the
+cutting lips break through. This catching of the drill
+may break it or move the work from its position. With
+a straight flute drill the cutting action is practically the
+same as with the flat drill shown at <a href="#Fig168">Fig. 168</a>, E and F.</p>
+
+<p>If a drill is employed in boring holes through close-grained,
+tough metals, as wrought or malleable iron and
+steel, the operation will be facilitated by lubricating the
+drill with plenty of lard oil or a solution of soda and
+water. Either of these materials will effectually remove
+the heat caused by the friction of the metal removed
+against the lips of the drill, and the danger of heating
+the drill to a temperature that will soften it by drawing
+the temper is minimized. In drilling large or deep holes
+it is good practice to apply the lubricating medium directly
+at the drill point. Special drills of the form shown
+at <a href="#Fig168">Fig. 168</a>, B, having a spiral oil tube running in a
+suitably formed channel, provides communication between
+the point of the drill and a suitable receiving hole on a
+drilled shank. The oil is supplied by a pump and its
+pressure not only promotes positive circulation and removal
+of heat, but also assists in keeping the hole free
+of chips. In drilling steel or wrought iron, lard oil
+applied to the point of the drill will facilitate the drilling,
+but this material should never be used with either
+brass or cast iron.</p>
+
+<p>The sizes to be provided depend upon the nature of
+the work and the amount of money that can be invested
+in drills. It is common practice to provide a set of drills,
+such as shown at <a href="#Fig169">Fig. 169</a>, which are carried in a suitable
+metal stand, these being known as number drills on account<span class='pagenum'><a name="Page_391" id="Page_391">[391]</a></span>
+of conforming to the wire gauge standards. Number
+drills do not usually run higher than <sup>5</sup>&#8260;<sub>16</sub> inch in
+diameter. Beyond this point drills are usually sold by
+the diameter. A set of chuck drills, ranging from <sup>3</sup>&#8260;<sub>8</sub> to
+<sup>3</sup>&#8260;<sub>4</sub> inch, advancing by <sup>1</sup>&#8260;<sub>32</sub> inch, and a set of Morse taper
+shank drills ranging from <sup>3</sup>&#8260;<sub>4</sub> to 1<sup>1</sup>&#8260;<sub>4</sub> inches, by increments
+of <sup>1</sup>&#8260;<sub>16</sub> inch, will be all that is needed for the most pretentious
+repair shop, as it is cheaper to bore holes larger
+than 1<sup>1</sup>&#8260;<sub>4</sub> inches with a boring tool than it is to carry a
+number of large drills in stock that would be used very
+seldom, perhaps not enough to justify their cost.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig169" id="Fig169"></a>
+<img src="images/illo386.jpg" alt="Fig. 169" width="400" height="312" />
+<p class="caption">Fig. 169.&mdash;Useful Set of Number Drills, Showing Stand for Keeping These
+in an Orderly Manner.</p></div>
+
+<p>In grinding drills, care must be taken to have the
+lips of the same length, so that they will form the same
+angle with the axis. If one lip is longer than the other,
+as shown in the flat drill at <a href="#Fig168">Fig. 168</a>, E, the hole will be
+larger than the drill size, and all the work of cutting will
+come upon the longest lip. The drill ends should be symmetrical,
+as shown at <a href="#Fig168">Fig. 168</a>, F.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig170" id="Fig170"></a>
+<img src="images/illo387.png" alt="Fig. 170" width="400" height="398" />
+<p class="caption">Fig. 170.&mdash;Illustrating Standard Forms of Hand and Machine Reamers.</p></div>
+
+<p>It is considered very difficult to drill a hole to an exact
+diameter, but for the most work a variation of a few
+thousandths of an inch is of no great moment. Where
+accuracy is necessary, holes must be reamed out to the
+required size. In reaming, a hole is drilled about <sup>1</sup>&#8260;<sub>32</sub>
+inch<span class='pagenum'><a name="Page_392" id="Page_392">[392]</a></span>
+smaller than is required, and is enlarged with a cutting
+tool known as the reamer. Reamers are usually of the
+fluted form shown at <a href="#Fig170">Fig. 170</a>, A. Tools of this nature
+are not designed to remove considerable amounts of
+metal, but are intended to augment the diameter of the
+drill hole by only a small fraction of an inch. Reamers
+are tapered slightly at the point in order that they will
+enter the hole easily, but the greater portion of the fluted
+part is straight, all cutting edges being parallel. Hand
+reamers are made in either the straight or taper forms,
+that at A, <a href="#Fig170">Fig. 170</a>, being straight, while B has tapering
+flutes. They are intended to be turned by a wrench similar
+to that employed in turning a tap, as shown at<span class='pagenum'><a name="Page_393" id="Page_393">[393]</a></span>
+<a href="#Fig172">Fig. 172</a>, C. The reamer shown at <a href="#Fig170">Fig. 170</a>, C, is a hand
+reamer. The form at D has spiral flutes similar to a
+twist drill, and as it is provided with a taper shank it is
+intended to be turned by power through the medium of
+a suitable collet.</p>
+
+<p>As the solid reamers must become reduced in size
+when sharpened, various forms of inserted blade reamers
+have been designed. One of these is shown at E, and as
+the cutting surfaces become reduced in diameter it is
+possible to replace the worn blades with others of proper
+size. Expanding reamers are of the form shown at F.
+These have a bolt passing through that fits into a tapering
+hole in the interior of the split reamer portion of the
+tool. If the hole is to be enlarged a few thousandths of
+an inch, it is possible to draw up on the nut just above
+the squared end of the shank, and by drawing the tapering
+wedge farther into the reamer body, the cutting portion
+will be expanded and will cut a larger hole.</p>
+
+<p>Reamers must be very carefully sharpened or there
+will be a tendency toward chattering with a consequent
+production of a rough surface. There are several methods
+of preventing this chattering, one being to separate the
+cutting edges by irregular spaces, while the most common
+method, and that to be preferred on machine reamers, is
+to use spiral flutes, as shown at <a href="#Fig170">Fig. 170</a>, D. Special
+taper reamers are made to conform to the various taper
+pin sizes which are sometimes used in holding parts together
+in an engine. A taper of <sup>1</sup>&#8260;<sub>16</sub> inch per foot is intended
+for holes where a pin, once driven in, is to remain
+in place. When it is desired that the pin be driven out,
+the taper is made steeper, generally <sup>1</sup>&#8260;<sub>4</sub> inch per foot,
+which is the standard taper used on taper pins.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig171" id="Fig171"></a>
+<img src="images/illo389.png" alt="Fig. 171" width="400" height="345" />
+<p class="caption">Fig. 171.&mdash;Tools for Thread Cutting.</p></div>
+
+<p>When threads are to be cut in a small hole, it will be
+apparent that it will be difficult to perform this operation
+economically on a lathe, therefore when internal threading
+is called for, a simple device known as a &#8220;tap&#8221; is
+used. There are many styles of taps, all conforming to
+different standards. Some are for metric or foreign<span class='pagenum'><a name="Page_394" id="Page_394">[394]</a></span>
+threads, some conform to the American standards, while
+others are used for pipe and tubing. Hand taps are the
+form most used in repair shops, these being outlined at
+<a href="#Fig171">Fig. 171</a>, A and B. They are usually sold in sets of three,
+known respectively as taper, plug, and bottoming. The
+taper tap is the one first put into the hole, and is then
+followed by the plug tap which cuts the threads deeper.
+If it is imperative that the thread should be full size
+clear to the bottom of the hole, the third tap of the set,
+which is straight-sided, is used. It would be difficult to
+start a bottoming tap into a hole because it would be
+larger in diameter at its point than the hole. The taper
+tap, as shown at A, <a href="#Fig171">Fig. 171</a>, has a portion of the cutting
+lands ground away at the point in order that it will enter
+the hole. The manipulation of a tap is not hard, as it
+does not need to be forced into the work, as the thread<span class='pagenum'><a name="Page_395" id="Page_395">[395]</a></span>
+will draw it into the hole as the tap is turned. The
+tapering of a tap is done so that no one thread is called
+upon to remove all of the metal, as for about half way up
+the length of the tap each succeeding thread is cut a
+little larger by the cutting edge until the full thread
+enters the hole. Care must be taken to always enter a
+tap straight in order to have the thread at correct angles
+to the surface.</p>
+
+<p>In cutting external threads on small rods or on small
+pieces, such as bolts and studs, it is not always economical
+to do this work in the lathe, especially in repair work.
+Dies are used to cut threads on pieces that are to be
+placed in tapped holes that have been threaded by the
+corresponding size of tap. Dies for small work are often
+made solid, as shown at <a href="#Fig171">Fig. 171</a>, C, but solid dies are
+usually limited to sizes below <sup>1</sup>&#8260;<sub>2</sub> inch. Sometimes the
+solid die is cylindrical in shape, with a slot through
+one side which enables one to obtain a slight degree of
+adjustment by squeezing the slotted portion together.
+Large dies, or the sizes over <sup>1</sup>&#8260;<sub>2</sub> inch, are usually made
+in two pieces in order that the halves may be closed up
+or brought nearer together. The advantage of this form
+of die is that either of the two pieces may be easily sharpened,
+and as it may be adjusted very easily the thread
+may be cut by easy stages. For example, the die may be
+adjusted to cut large, which will produce a shallow thread
+that will act as an accurate guide when the die is closed
+up and a deeper thread cut.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig172" id="Fig172"></a>
+<img src="images/illo391.png" alt="Fig. 172" width="400" height="407" />
+<p class="caption">Fig. 172.&mdash;Showing Holder Designs for One- and Two-Piece Thread Cutting
+Dies.</p></div>
+
+<p>A common form of die holder for an adjustable die is
+shown at <a href="#Fig172">Fig. 172</a>, A. As will be apparent, it consists
+of a central body portion having guide members to keep
+the die pieces from falling out and levers at each end in
+order to permit the operator to exert sufficient force to
+remove the metal. The method of adjusting the depth of
+thread with a clamp screw when a two-piece die is employed
+is also clearly outlined. The diestock shown at
+B is used for the smaller dies of the one-piece pattern,
+having a slot in order that they may be closed up slightly<span class='pagenum'><a name="Page_396" id="Page_396">[396]</a></span>
+by the clamp screw. The reverse side of the diestock
+shown at B is outlined below it, and the guide pieces,
+which may be easily moved in or out, according to the
+size of the piece to be threaded by means of eccentrically
+disposed semi-circular slots in the adjustment plate, are
+shown. These movable guide members have small pins
+let into their surface which engage the slots, and they
+may be moved in or out, as desired, according to the position
+of the adjusting plate. The use of the guide pieces
+makes for accurate positioning or centering of the rod to
+be threaded. Dies are usually sold in sets, and are commonly
+furnished as a portion of a complete outfit such as<span class='pagenum'><a name="Page_397" id="Page_397">[397]</a></span>
+outlined at <a href="#Fig173">Fig. 173</a>. That shown has two sizes of diestock,
+a tap wrench, eight assorted dies, eight assorted
+taps, and a small screw driver for adjusting the die. An
+automobile repair shop should be provided with three
+different sets of taps and dies, as three different standards
+for the bolts and nuts are used in fastening automobile
+components. These are the American, metric
+(used on foreign engines), and the S. A. E. standard
+threads. A set of pipe dies and taps will also be found
+useful.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig173" id="Fig173"></a>
+<img src="images/illo392.png" alt="Fig. 173" width="500" height="234" />
+<p class="caption">Fig. 173.&mdash;Useful Outfit of Taps and Dies for the Engine Repair Shop.</p></div>
+
+<h3><a name="SecXI_8" id="SecXI_8"></a>MEASURING TOOLS</h3>
+
+<p>The tool outfit of the machinist or the mechanic who
+aspires to do machine work must include a number of
+measuring tools which are not needed by the floor man or
+one who merely assembles and takes apart the finished
+pieces. The machinist who must convert raw material
+into finished products requires a number of measuring
+tools, some of which are used for taking only approximate
+measurements, such as calipers and scales, while
+others are intended to take very accurate measurements,
+such as the Vernier and the micrometer. A number of
+common forms of calipers are shown at <a href="#Fig174">Fig. 174</a>. These
+are known as inside or outside calipers, depending upon
+the measurements they are intended to take. That at A<span class='pagenum'><a name="Page_398" id="Page_398">[398]</a></span>
+is an inside caliper, consisting of two legs, A and D, and
+a gauging piece, B, which can be locked to leg A, or released
+from that member by the screw, C. The object of
+this construction is to permit of measurements being
+taken at the bottom of a two diameter hole, where the
+point to be measured is of larger diameter than the portion
+of the hole through which the calipers entered. It
+will be apparent that the legs A and D must be brought
+close together to pass through the smaller holes. This
+may be done without losing the setting, as the guide bar
+B will remain in one position as determined by the size
+of the hole to be measured, while the leg A may be swung
+in to clear the obstruction as the calipers are lifted out.
+When it is desired to ascertain the measurements the leg
+A is pushed back into place into the slotted portion of the
+guide B, and locked by the clamp screw C. A tool of this
+form is known as an internal transfer caliper.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig174" id="Fig174"></a>
+<img src="images/illo393.png" alt="Fig. 174" width="450" height="329" />
+<p class="caption">Fig. 174.&mdash;Common Forms of Inside and Outside Calipers.</p></div>
+
+<p>The form of caliper shown at B is an outside caliper.
+Those at C and D are special forms for inside and outside<span class='pagenum'><a name="Page_399" id="Page_399">[399]</a></span>
+work, the former being used, if desired, as a divider,
+while the latter may be employed for measuring the
+walls of tubing. The calipers at E are simple forms,
+having a friction joint to distinguish them from the spring
+calipers shown at B, C and D. In order to permit of
+ready adjustment of a spring caliper, a split nut as shown
+at G is sometimes used. A solid nut caliper can only be
+adjusted by screwing the nut in or out on the screw,
+which may be a tedious process if the caliper is to be set
+from one extreme to the other several times in succession.
+With a slip nut as shown at G it is possible to slip it
+from one end of the thread to the other without turning
+it, and of locking it in place at any desired point by
+simply allowing the caliper leg to come in contact with
+it. The method of adjusting a spring caliper is shown
+at <a href="#Fig174">Fig. 174</a>, H.</p>
+
+<p>Among the most common of the machinist&#8217;s tools are
+those used for linear measurements. The usual forms are
+shown in group, <a href="#Fig175">Fig. 175</a>. The most common tool, which
+is widely known, is the carpenter&#8217;s folding two-foot rule
+or the yardstick. While these are very convenient for
+taking measurements where great accuracy is not required,
+the machinist must work much more accurately
+than the carpenter, and the standard steel scale which is
+shown at D, is a popular tool for the machinist. The
+steel scale is in reality a graduated straight edge and
+forms an important part of various measuring tools.
+These are made of high grade steel and vary from 1 to
+48 inches in length. They are carefully hardened in order
+to preserve the graduations, and all surfaces and edges
+are accurately ground to insure absolute parallelism. The
+graduations on the high grade scales are produced with
+a special device known as a dividing engine, but on
+cheaper scales, etching suffices to provide a fairly accurate
+graduation. The steel scales may be very thin and flexible,
+or may be about an eighth of an inch thick on the
+twelve-inch size, which is that commonly used with combination
+squares, protractors and other tools of that<span class='pagenum'><a name="Page_400" id="Page_400">[400]</a></span>
+nature. The repairman&#8217;s scale should be graduated both
+with the English system, in which the inches are divided
+into eighths, sixteenths, thirty-secondths and sixty-fourths,
+and also in the metric system, divided into millimeters
+and centimeters. Some machinists use scales
+graduated in tenths, twentieths, fiftieths and hundredths.<span class='pagenum'><a name="Page_401" id="Page_401">[401]</a></span>
+This is not as good a system of graduation as the more
+conventional one first described.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig175" id="Fig175"></a>
+<img src="images/illo395.png" alt="Fig. 175" width="400" height="535" />
+<p class="caption">Fig. 175.&mdash;Measuring Appliances for the Machinist and Floor Man.</p></div>
+
+<p>Some steel scales are provided with a slot or groove
+cut the entire length on one side and about the center of
+the scales. This permits the attachment of various fittings
+such as the protractor head, which enables the machinist
+to measure angles, or in addition the heads convert
+the scale into a square or a tool permitting the accurate
+bisecting of pieces of circular section. Two scales are
+sometimes joined together to form a right angle, such as
+shown at <a href="#Fig175">Fig. 175</a>, C. This is known as a square and is
+very valuable in ascertaining the truth of vertical pieces
+that are supposed to form a right angle with a base piece.</p>
+
+<p>The Vernier is a device for reading finer divisions on
+a scale than those into which the scale is divided. Sixty-fourths
+of an inch are about the finest division that can
+be read accurately with the naked eye. When fine work
+is necessary a Vernier is employed. This consists essentially
+of two rules so graduated that the true scale has
+each inch divided into ten equal parts, the upper or Vernier
+portion has ten divisions occupying the same space
+as nine of the divisions of the true scale. It is evident,
+therefore, that one of the divisions of the Vernier is equal
+to nine-tenths of one of those on the true scale. If the
+Vernier scale is moved to the right so that the graduations
+marked &#8220;1&#8221; shall coincide, it will have moved one-tenth
+of a division on the scale or one-hundredth of an
+inch. When the graduations numbered 5 coincide the
+Vernier will have moved five-hundredths of an inch; when
+the lines marked 0 and 10 coincide, the Vernier will have
+moved nine-hundredths of an inch, and when 10 on the
+Vernier comes opposite 10 on the scales, the upper rule
+will have moved ten-hundredths of an inch, or the whole
+of one division on the scale. By this means the scale,
+though it may be graduated only to tenths of an inch,
+may be accurately set at points with positions expressed
+in hundredths of an inch. When graduated to read in
+thousandths, the true scale is divided into fifty parts and<span class='pagenum'><a name="Page_402" id="Page_402">[402]</a></span>
+the Vernier into twenty parts. Each division of the Vernier
+is therefore equal to nineteen-twentieths of one of
+the true scale. If the Vernier be moved so the lines of
+the first division coincide, it will have moved one-twentieth
+of one-fiftieth, or .001 inch. The Vernier principle
+can be readily grasped by studying the section of the
+Vernier scale and true scale shown at <a href="#Fig176">Fig. 176</a>, A.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig176" id="Fig176"></a>
+<img src="images/illo397.png" alt="Fig. 176" width="500" height="294" />
+<p class="caption">Fig. 176.&mdash;At Left, Special Form of Vernier Caliper for Measuring Gear
+Teeth; at Right, Micrometer for Accurate Internal Measurements.</p></div>
+
+<p>The caliper scale which is shown at <a href="#Fig175">Fig. 175</a>, A, permits
+of taking the over-all dimension of any parts that
+will go between the jaws. This scale can be adjusted very
+accurately by means of a fine thread screw attached to a
+movable jaw and the divisions may be divided by eye
+into two parts if one sixty-fourth is the smallest of the
+divisions. A line is indicated on the movable jaw and
+coincides with the graduations on the scale. As will be
+apparent, if the line does not coincide exactly with one
+of the graduations it will be at some point between the
+lines and the true measurement may be approximated without
+trouble.</p>
+
+<p>A group of various other measuring tools of value to
+the machinist is shown at <a href="#Fig177">Fig. 177</a>. The small scale at A
+is termed a &#8220;center gauge,&#8221; because it can be used to
+test<span class='pagenum'><a name="Page_403" id="Page_403">[403]</a></span>
+the truth of the taper of either a male or female lathe
+center. The two smaller nicks, or v&#8217;s, indicate the shape
+of a standard thread, and may be used as a guide for
+grinding the point of a thread-cutting tool. The cross
+level which is shown at B is of marked utility in erecting,
+as it will indicate absolutely if the piece it is used to test
+is level. It will indicate if the piece is level along its
+width as well as its length.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig177" id="Fig177"></a>
+<img src="images/illo398.jpg" alt="Fig. 177" width="500" height="391" />
+<p class="caption">Fig. 177.&mdash;Measuring Appliances of Value in Airplane Repair Work.</p></div>
+
+<p>A very simple attachment for use with a scale that
+enables the machinist to scribe lines along the length of
+a cylindrical piece is shown at <a href="#Fig177">Fig. 177</a>, C. These are
+merely small wedge-shaped clamps having an angular
+face to rest upon the bars. The thread pitch gauge which
+is shown at <a href="#Fig177">Fig. 177</a>, D, is an excellent pocket tool for the
+mechanic, as it is often necessary to determine without
+loss of time the pitch of the thread on a bolt or in a nut.
+This consists of a number of leaves having serrations on
+one edge corresponding to the standard thread it is to be<span class='pagenum'><a name="Page_404" id="Page_404">[404]</a></span>
+used in measuring. The tool shown gives all pitches up
+to 48 threads per inch. The leaves may be folded in out
+of the way when not in use, and their shape admits of
+their being used in any position without the remainder
+of the set interfering with the one in use. The fine pitch
+gauges have slim, tapering leaves of the correct shape to
+be used in finding the pitch of small nuts. As the tool is
+round when the leaves are folded back out of the way, it
+is an excellent pocket tool, as there are no sharp corners
+to wear out the pocket. Practical application of a Vernier
+having measuring heads of special form for measuring
+gear teeth is shown at <a href="#Fig176">Fig. 176</a>, A. As the action of
+this tool has been previously explained, it will not be
+necessary to describe it further.</p>
+
+<h3><a name="SecXI_9" id="SecXI_9"></a>MICROMETER CALIPERS AND THEIR USE</h3>
+
+<p>Where great accuracy is necessary in taking measurements
+the micrometer caliper, which in the simple form
+will measure easily .001 inch (one-thousandth part of an
+inch) and when fitted with a Vernier that will measure
+.0001 inch (one ten-thousandth part of an inch), is used.
+The micrometer may be of the caliper form for measuring
+outside diameters or it may be of the form shown at
+<a href="#Fig176">Fig. 176</a>, B, for measuring internal diameters. The operation
+of both forms is identical except that the internal
+micrometer is placed inside of the bore to be measured
+while the external form is used just the same as a caliper.
+The form outlined will measure from one and one-half to
+six and a half inches as extension points are provided to
+increase the range of the instrument. The screw has a
+movement of one-half inch and a hardened anvil is placed
+in the end of the thimble in order to prevent undue wear
+at that point. The extension points or rods are accurately
+made in standard lengths and are screwed into the body
+of the instrument instead of being pushed in, this insuring
+firmness and accuracy. Two forms of micrometers
+for external measurements are shown at <a href="#Fig178">Fig. 178</a>.
+The<span class='pagenum'><a name="Page_405" id="Page_405">[405]</a></span>
+top one is graduated to read in thousandths of an inch,
+while the lower one is graduated to indicate hundredths
+of a millimeter. The mechanical principle involved in the
+construction of a micrometer is that of a screw free to
+move in a fixed nut. An opening to receive the work to
+be measured is provided by the backward movement of the
+thimble which turns the screw and the size of the opening
+is indicated by the graduations on the barrel.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig178" id="Fig178"></a>
+<img src="images/illo400.png" alt="Fig. 178" width="400" height="473" />
+<p class="caption">Fig. 178.&mdash;Standard Forms of Micrometer Caliper for External Measurements.</p></div>
+
+<p><span class='pagenum'><a name="Page_406" id="Page_406">[406]</a></span>The article to be measured is placed between the anvil
+and spindle, the frame being held stationary while the
+thimble is revolved by the thumb and finger. The pitch
+of the screw thread on the concealed part of the spindle
+is 40 to an inch. One complete revolution of the spindle,
+therefore, moves it longitudinally one-fortieth, or twenty-five
+thousandths of an inch. As will be evident from the
+development of the scale on the barrel of the inch micrometer,
+the sleeve is marked with forty lines to the
+inch, each of these lines indicating twenty-five thousandths.
+The thimble has a beveled edge which is graduated
+into twenty-five parts. When the instrument is
+closed the graduation on the beveled edge of the thimble
+marked 0 should correspond to the 0 line on the barrel.
+If the micrometer is rotated one full turn the opening
+between the spindle and anvil will be .025 inch. If the
+thimble is turned only one graduation, or one twenty-fifth
+of a revolution, the opening between the spindle and
+anvil will be increased only by .001 inch (one-thousandth
+of an inch).</p>
+
+<p>As many of the dimensions of the airplane parts,
+especially of those of foreign manufacture or such parts
+as ball and roller bearings, are based on the metric system,
+the competent repairman should possess both inch
+and metric micrometers in order to avoid continual reference
+to a table of metric equivalents. With a metric micrometer
+there are fifty graduations on the barrel, these
+representing .01 of a millimeter, or approximately .004
+inch. One full turn of the barrel means an increase of
+half a millimeter, or .50 mm. (fifty one-hundredths). As
+it takes two turns to augment the space between the anvil
+and the stem by increments of one millimeter, it will be
+evident that it would not be difficult to divide the spaces
+on the metric micrometer thimble in halves by the eye,
+and thus the average workman can measure to .0002 inch
+plus or minus without difficulty. As set in the illustration,
+the metric micrometers show a space of 13.5 mm.,
+or about one millimeter more than half an inch. The<span class='pagenum'><a name="Page_407" id="Page_407">[407]</a></span>
+inch micrometer shown is set to five-tenths or five hundred
+one-thousandths or one-half inch. A little study of
+the foregoing matter will make it easy to understand the
+action of either the inch or metric micrometer.</p>
+
+<p>Both of the micrometers shown have a small knurled
+knob at the end of the barrel. This controls the ratchet
+stop, which is a device that permits a ratchet to slip by
+a pawl when more than a certain amount of pressure is
+applied, thereby preventing the measuring spindle from
+turning further and perhaps springing the instrument. A
+simple rule that can be easily memorized for reading the
+inch micrometer is to multiply the number of vertical
+divisions on the sleeve by 25 and add to that the number
+of divisions on the bevel of the thimble reading from the
+zero to the line which coincides with the horizontal line on
+the sleeve. For example: if there are ten divisions visible
+on the sleeve, multiply this number by 25, then add
+the number of divisions shown on the bevel of the thimble,
+which is 10. The micrometer is therefore opened
+10 &times; 25 equals 250 plus 10 equals 260 thousandths.</p>
+
+<p>Micrometers are made in many sizes, ranging from
+those having a maximum opening of one inch to special
+large forms that will measure forty or more inches.
+While it is not to be expected that the repairman will have
+use for the big sizes, if a caliper having a maximum
+opening of six inches is provided with a number of extension
+rods enabling one to measure smaller objects,
+practically all of the measuring needed in repairing engine
+parts can be made accurately. Two or three smaller
+micrometers having a maximum range of two or three
+inches will also be found valuable, as most of the measurements
+will be made with these tools which will be much
+easier to handle than the larger sizes.</p>
+
+<h3><a name="SecXI_10" id="SecXI_10"></a>TYPICAL TOOL OUTFITS</h3>
+
+<p>The equipment of tools necessary for repairing airplane
+engines depends entirely upon the type of the power<span class='pagenum'><a name="Page_408" id="Page_408">[408]</a></span>
+plant and while the common hand tools can be used on
+all forms, the work is always facilitated by having special
+tools adapted for reaching the nuts and screws that would
+be hard to reach otherwise. Special spanners and socket
+wrenches are very desirable. Then again, the nature of
+the work to be performed must be taken into consideration.
+Rebuilding or overhauling an engine calls for considerably
+more tools than are furnished for making field
+repairs or minor adjustments. A complete set of tools
+supplied to men working on Curtiss OX-2 engines and
+JN-4 training biplanes is shown at <a href="#Fig179">Fig. 179</a>. The tools
+are placed in a special box provided with a hinged cover
+and are arranged in the systematic manner outlined.
+The various tools and supplies shown are: A, hacksaw
+blades; B, special socket wrenches for engine bolts and
+nuts; C, ball pein hammers, four sizes; D, five assorted
+sizes of screw drivers ranging from very long for heavy
+work to short and small for fine work; E, seven pairs of
+pliers including combination in three sizes, two pairs of
+cutting pliers and one round nose; F, two split pin extractors
+and spreaders; G, wrench set including three
+adjustable monkey wrenches, one Stillson or pipe wrench,
+five sizes adjustable end wrenches and ten double end
+S wrenches; H, set of files, including flat, three cornered
+and half round; I, file brush; J, chisel and drift pin;
+K, three small punches or drifts; L, hacksaw frame; M,
+soldering copper; N, special spanners for propeller retaining
+nuts; O, special spanners; P, socket wrenches,
+long handle; Q, long handle, stiff bristle brushes for
+cleaning motor; R, gasoline blow torch; S, hand drill;
+T, spools of safety wire; U, flash lamp; V, special puller
+and castle wrenches; W, oil can; X, large adjustable
+monkey wrench; Y, washer and gasket cutter; Z, ball of
+heavy twine. In addition to the tools, various supplies,
+such as soldering acid, solder, shellac, valve grinding compound,
+bolts and nuts, split pins, washers, wood screws,
+etc., are provided.</p>
+
+<p class='pagenum' style="margin-top: -1.5em;"><a name="Page_409" id="Page_409">[409]</a></p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig179" id="Fig179"></a>
+<img src="images/illo404.png" alt="Fig. 179" width="600" height="373" />
+<p class="caption">Fig. 179.&mdash;Special Tools for Maintaining Curtiss OX-2 Motor Used in Curtiss JN-4 Training Biplane.</p></div>
+
+<p class='pagenum'><a name="Page_410" id="Page_410">[410]</a></p>
+
+<h3><a name="SecXI_11" id="SecXI_11"></a>SPECIAL HALL-SCOTT TOOLS</h3>
+
+<table class="fsize80" summary="Table p. 410-411">
+
+<tr>
+<td class="center padl1 padr1">NO.</td>
+<td class="center padl1 padr1">TOOL</td>
+<td class="center padl1 padr1">DIRECTIONS FOR USE</td>
+</tr>
+
+<tr>
+<td class="right top padr1">1</td>
+<td class="left top padl1 padr1">Engine hoisting hook, 6-cylinder</td>
+<td class="left top padl1 padr1">Hook under cam-shaft housing, when hoisting engine.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">2</td>
+<td class="left top padl1 padr1">Engine hoisting hook, 4-cylinder</td>
+<td class="left top padl1 padr1">Hook under cam-shaft housing, when hoisting engine.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">3</td>
+<td class="left top padl1 padr1">Water plug wrench</td>
+<td class="left top padl1 padr1">For use on water plugs on top and end of cylinders.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">4</td>
+<td class="left top padl1 padr1">Vertical shaft flange puller</td>
+<td class="left top padl1 padr1">For pulling lower pinion shaft flange from shaft. (Used on A-5 and A-7 engines only.)</td>
+</tr>
+
+<tr>
+<td class="right top padr1">5</td>
+<td class="left top padl1 padr1">Oil gun</td>
+<td class="left top padl1 padr1">For general lubrication use.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">6</td>
+<td class="left top padl1 padr1">Magneto gear puller</td>
+<td class="left top padl1 padr1">For pulling magneto gears from magneto shaft.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">7</td>
+<td class="left top padl1 padr1">Socket wrench, <span class="nowrap"><sup>1</sup>&#8260;<sub>4</sub>&#8242;&#8242;</span> A.L.A.M.</td>
+<td class="left top padl1 padr1">For use on bolts and nuts on crank cases.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">8</td>
+<td class="left top padl1 padr1">Socket wrench, <span class="nowrap"><sup>1</sup>&#8260;<sub>4</sub>&#8242;&#8242;</span> A.L.A.M</td>
+<td class="left top padl1 padr1">For use on crank cases and magneto gear housings.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">9</td>
+<td class="left top padl1 padr1">Socket wrench, <span class="nowrap"><sup>1</sup>&#8260;<sub>4</sub>&#8242;&#8242;</span> A.L.A.M.</td>
+<td class="left top padl1 padr1">For use on magneto gear housings.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">10</td>
+<td class="left top padl1 padr1">Socket wrench, <span class="nowrap"><sup>3</sup>&#8260;<sub>8</sub>&#8242;&#8242;</span> standard</td>
+<td class="left top padl1 padr1">For bolts and nuts which fasten magnetos to crank-case.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">11</td>
+<td class="left top padl1 padr1">Socket wrench, <span class="nowrap"><sup>1</sup>&#8260;<sub>4</sub>&#8242;&#8242;</span> A.L.A.M.</td>
+<td class="left top padl1 padr1">For use on magneto gear housings.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">12</td>
+<td class="left top padl1 padr1">Vertical shaft gear puller</td>
+<td class="left top padl1 padr1">For removing water pump and magneto drive gear.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">13</td>
+<td class="left top padl1 padr1">Brace and facing cutter</td>
+<td class="left top padl1 padr1">For facing lugs on cylinders for cylinder hold down stud washers.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">14</td>
+<td class="left top padl1 padr1">Handle for brace</td>
+<td class="left top padl1 padr1">Use with brace.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">15</td>
+<td class="left top padl1 padr1">Valve grinding brace</td>
+<td class="left top padl1 padr1">For grinding in valves.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">16</td>
+<td class="left top padl1 padr1">Socket wrench base, <span class="nowrap"><sup>3</sup>&#8260;<sub>8</sub>&#8242;&#8242;</span> A.L.A.M.</td>
+<td class="left top padl1 padr1">For thrust bearing cap screws.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">17</td>
+<td class="left top padl1 padr1">Brace and facing cutter, <span class="nowrap"><sup>5</sup>&#8260;<sub>16</sub>&#8242;&#8242;</span> A.L.A.M.</td>
+<td class="left top padl1 padr1">For facing lugs on rocker arm covers.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">18</td>
+<td class="left top padl1 padr1">Valve grinding screw driver</td>
+<td class="left top padl1 padr1">For grinding in valves.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">19</td>
+<td class="left top padl1 padr1">Valve spring tool</td>
+<td class="left top padl1 padr1">For putting on and taking off valve springs.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">20</td>
+<td class="left top padl1 padr1">Block-valve spring tool</td>
+<td class="left top padl1 padr1">For use with valve spring tool.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">21</td>
+<td class="left top padl1 padr1">Socket wrench, <span class="nowrap"><sup>5</sup>&#8260;<sub>8</sub>&#8242;&#8242;</span> A.L.A.M.</td>
+<td class="left top padl1 padr1">For main bearing nuts.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">22</td>
+<td class="left top padl1 padr1">Socket wrench, <span class="nowrap"><sup>1</sup>&#8260;<sub>4</sub>&#8242;&#8242;</span> A.L.A.M.</td>
+<td class="left top padl1 padr1">For use on cam-shaft housing.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">23</td>
+<td class="left top padl1 padr1">Socket wrench, <span class="nowrap"><sup>5</sup>&#8260;<sub>16</sub>&#8242;&#8242;</span> A.L.A.M.</td>
+<td class="left top padl1 padr1">For cam-shaft housing hold down stud nuts.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">24</td>
+<td class="left top padl1 padr1">Socket wrench, <span class="nowrap"><sup>1</sup>&#8260;<sub>2</sub>&#8242;&#8242;</span> A.L.A.M.</td>
+<td class="left top padl1 padr1">For cylinder hold down stud nuts.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">25</td>
+<td class="left top padl1 padr1">Socket wrench, <span class="nowrap"><sup>5</sup>&#8260;<sub>16</sub>&#8242;&#8242;</span> A.L.A.M.</td>
+<td class="left top padl1 padr1">For carburetor and water pump bolts and nuts.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">26</td>
+<td class="left top padl1 padr1">Socket wrench, <span class="nowrap"><sup>5</sup>&#8260;<sub>16</sub>&#8242;&#8242;</span> A.L.A.M.</td>
+<td class="left top padl1 padr1">For carburetor and water pump bolts and nuts.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">27</td>
+<td class="left top padl1 padr1">Socket wrench</td>
+<td class="left top padl1 padr1">For use on carburetor jets.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">28</td>
+<td class="left top padl1 padr1">Magneto screw driver</td>
+<td class="left top padl1 padr1">For general magneto use.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">29</td>
+<td class="left top padl1 padr1">Brass bar, <span class="nowrap">1&#8242;&#8242;</span> diameter &times; <span class="nowrap">7&#8242;&#8242;</span> long</td>
+<td class="left top padl1 padr1">For driving piston pins from pistons.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">30</td>
+<td class="left top padl1 padr1">Hack saw</td>
+<td class="left top padl1 padr1">For general use.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">31</td>
+<td class="left top padl1 padr1">Oil can</td>
+<td class="left top padl1 padr1">For cam-shaft housing lubrication.<span class='pagenum'
+style="font-size: 100%;"><a name="Page_411" id="Page_411">[411]</a></span></td>
+</tr>
+
+<tr>
+<td class="right top padr1">32</td>
+<td class="left top padl1 padr1">Gasoline or distillate can</td>
+<td class="left top padl1 padr1">For priming or other use.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">33</td>
+<td class="left top padl1 padr1">Oil can</td>
+<td class="left top padl1 padr1">For magneto gear lubrication.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">34</td>
+<td class="left top padl1 padr1">Shellac can</td>
+<td class="left top padl1 padr1">For rubber hose connections and gaskets.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">35</td>
+<td class="left top padl1 padr1">Magneto cleaner</td>
+<td class="left top padl1 padr1">For use on magnetos.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">36</td>
+<td class="left top padl1 padr1">Clamps</td>
+<td class="left top padl1 padr1">For holding cylinder hold down studs, when fitting main bearings.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">37</td>
+<td class="left top padl1 padr1">Piston guards</td>
+<td class="left top padl1 padr1">For use in pistons, when out of engine, to protect them.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">38</td>
+<td class="left top padl1 padr1">Screw driver</td>
+<td class="left top padl1 padr1">For general use.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">39</td>
+<td class="left top padl1 padr1">Vertical shaft clamps</td>
+<td class="left top padl1 padr1">For clamping vertical shaft flanges, when timing engine.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">40</td>
+<td class="left top padl1 padr1">Thrust adjusting nut wrench</td>
+<td class="left top padl1 padr1">For adjusting propeller thrust bearing.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">41</td>
+<td class="left top padl1 padr1">Stuffing box spanner wrench</td>
+<td class="left top padl1 padr1">For adjusting stuffing box nut on vertical shaft.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">42</td>
+<td class="left top padl1 padr1">Water pump spanner wrench</td>
+<td class="left top padl1 padr1">For adjusting water pump stuffing nut.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">43</td>
+<td class="left top padl1 padr1">Wrench</td>
+<td class="left top padl1 padr1">For use on cylinder relief cocks and cylinder priming cocks.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">44</td>
+<td class="left top padl1 padr1">Hose clamp wrench</td>
+<td class="left top padl1 padr1">For use on hose clamps.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">45</td>
+<td class="left top padl1 padr1">Scraper</td>
+<td class="left top padl1 padr1">For cleaning piston ring grooves on pistons.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">46</td>
+<td class="left top padl1 padr1">Crank-shaft nut wrench</td>
+<td class="left top padl1 padr1">For adjusting crank-shaft nut.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">47</td>
+<td class="left top padl1 padr1">Spark-plug wrench</td>
+<td class="left top padl1 padr1">For putting in and taking out spark-plugs in cylinders.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">48</td>
+<td class="left top padl1 padr1">Timing disc (single disc)</td>
+<td class="left top padl1 padr1">For use on crank-shaft to time engine.</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td colspan="2" class="left top padl5 padr1">Specify type motor disc should be made for. If double disc is required, specify the two types of motors the disc is to be made for. Double disc.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">49</td>
+<td class="left top padl1 padr1">Main bearing scraper</td>
+<td class="left top padl1 padr1">For scraping in bearings.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">50</td>
+<td class="left top padl1 padr1">Cylinder carbon scraper</td>
+<td class="left top padl1 padr1">For removing carbon from heads of cylinders.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">51</td>
+<td class="left top padl1 padr1">Valve seating tool</td>
+<td class="left top padl1 padr1">For seating valves in cylinder heads.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">52</td>
+<td class="left top padl1 padr1">Scraper, small</td>
+<td class="left top padl1 padr1">For general bearing use.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">53</td>
+<td class="left top padl1 padr1">Scraper, large</td>
+<td class="left top padl1 padr1">For general bearing use.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">54</td>
+<td class="left top padl1 padr1">Crank-shaft flange puller</td>
+<td class="left top padl1 padr1">For pulling crank-shaft flange from crank-shaft.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">55</td>
+<td colspan="2" class="left top padl1 padr1">Piston and connecting rod racks.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">56</td>
+<td colspan="2" class="left top padl1 padr1">Main bearing stud nuts and shim rack.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">57</td>
+<td colspan="2" class="left top padl1 padr1">Main bearing board rack.</td>
+</tr>
+
+<tr>
+<td class="right top padr1">58</td>
+<td colspan="2" class="left top padl1 padr1">Rocker arm and cover rack.</td>
+</tr>
+
+</table>
+
+<p><span class='pagenum'><a name="Page_412" id="Page_412">[412]</a></span>The special tools and fixtures recommended by the
+Hall-Scott Company for work on their engines are clearly
+shown at <a href="#Fig180">Fig. 180</a>. All tools are numbered and their uses
+may be clearly understood by reference to the <a href="#Fig180">illustration</a>
+and explanatory list given on <a href="#Page_410">pages 410</a> and <a href="#Page_411">411</a>.</p>
+
+<h3><a name="SecXI_12" id="SecXI_12"></a>OVERHAULING AIRPLANE ENGINES</h3>
+
+<p>After an airplane engine has been in use for a period
+ranging from 60 to 80 hours, depending upon the type,
+it is necessary to give it a thorough overhauling before
+it is returned to service. To do this properly, the engine
+is removed from the fuselage and placed on a special supporting
+stand, such as shown at <a href="#Fig181">Fig. 181</a>, so it can be
+placed in any position and completely dismantled. With
+a stand of this kind it is as easy to work on the bottom
+of the engine as on the top and every part can be instantly
+reached. The crank-case shown in place in illustration
+is in a very convenient position for scraping in
+the crank-shaft bearings.</p>
+
+<p class='pagenum' style="margin-top: -1.5em;"><a name="Page_413" id="Page_413">[413]</a></p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig180" id="Fig180"></a>
+<img src="images/illo408.png" alt="Fig. 180" width="600" height="346" />
+<p class="caption">Fig. 180.&mdash;Special Tools and Appliances to Facilitate Overhauling Work on Hall-Scott Airplane Engines.</p></div>
+
+<p><a name="SecXI_13" id="SecXI_13"></a>In order to look over the parts of an engine and to
+restore the worn or defective components it is necessary
+to take the engine entirely apart, as it is only when the
+power plant is thoroughly dismantled that the parts can
+be inspected or measured to determine defects or wear.
+If one is not familiar with the engine to be inspected,
+even though the work is done by a repairman of experience,
+it will be found of value to take certain precautions
+when dismantling the engine in order to insure that all
+parts will be replaced in the same position they occupied
+before removal. There are a number of ways of identifying
+the parts, one of the simplest and surest being to
+mark them with steel numbers or letters or with a series
+of center punch marks in order to retain the proper relation
+when reassembling. This is of special importance
+in connection with dismantling multiple cylinder engines
+as it is vital that pistons, piston rings, connecting rods,
+valves, and other cylinder parts be always replaced in<span class='pagenum'><a name="Page_414" id="Page_414">[414]</a></span>
+the same cylinder from which they were removed, because
+it is uncommon to find equal depreciation in all
+cylinders. Some repairmen use small shipping tags to
+identify the pieces. This can be criticised because the
+tags may become detached and lost and the identity of
+the piece mistaken. If the repairing is being done in a
+shop where other engines of the same make are being
+worked on, the repairman should be provided with a large
+chest fitted with a lock and key in which all of the smaller
+parts, such as rods, bolts and nuts, valves, gears, valve
+springs, cam-shafts, etc., may be stored to prevent the
+possibility of confusion with similar members of other<span class='pagenum'><a name="Page_415" id="Page_415">[415]</a></span>
+engines. All parts should be thoroughly cleaned with
+gasoline or in the potash kettle as removed, and wiped
+clean and dry. This is necessary to show wear which will
+be evidenced by easily identified indications in cases
+where the machine has been used for a time, but in others,
+the deterioration can only be detected by delicate measuring
+instruments.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig181" id="Fig181"></a>
+<img src="images/illo409.jpg" alt="Fig. 181" width="450" height="478" />
+<p class="caption">Fig. 181.&mdash;Special Stand to Make Motor Overhauling Work Easier.</p></div>
+
+<p>In taking down a motor the smaller parts and fittings
+such as spark-plugs, manifolds and wiring should be removed
+first. Then the more important members such as cylinders
+may be removed from the crank-case to give access
+to the interior and make possible the examination of the
+pistons, rings and connecting rods. After the cylinders are
+removed the next operation is to disconnect the connecting
+rods from the crank-shaft and to remove them and
+the pistons attached as a unit. Then the crank-case is
+dismembered, in most cases by removing the bottom half
+or oil sump, thus exposing the main bearings and crank-shaft.
+The first operation is the removal of the inlet and
+exhaust manifolds. In some cases the manifolds are
+cored integral with the cylinder head casting and it is
+merely necessary to remove a short pipe leading from the
+carburetor to one inlet opening and the exhaust pipe from
+the outlet opening common to all cylinders. In order to
+remove the carburetor it is necessary to shut off the gasoline
+supply at the tank and to remove the pipe coupling
+at the float chamber. It is also necessary to disconnect
+the throttle operating rod. After the cylinders are removed
+and before taking the crank-case apart it is well
+to remove the water pump and magneto. The wiring on
+most engines of modern development is carried in conduits
+and usually releasing two or three minor fastenings
+will permit one to take off the plug wiring as a unit.
+The wire should be disconnected from both spark-plugs
+and magneto distributor before its removal. When the
+cylinders are removed, the pistons, piston rings, and connecting
+rods are clearly exposed and their condition may
+be readily noticed.</p>
+
+<p><span class='pagenum'><a name="Page_416" id="Page_416">[416]</a></span>Before disturbing the arrangement of the timing
+gears, it is important that these be marked so that they
+will be replaced in exactly the same relation as intended
+by the engine designer. If the gears are properly marked
+the valve timing and magneto setting will be undisturbed
+when the parts are replaced after overhauling. With the
+cylinders off, it is possible to ascertain if there is any
+undue wear present in the connecting rod bearings at
+either the wrist pin or crank-pin ends and also to form
+some idea of the amount of carbon deposits on the piston
+top and back of the piston rings. Any wear of the timing
+gears can also be determined. The removal of the
+bottom plate of the engine enables the repairman to see
+if the main bearings are worn unduly. Often bearings
+may be taken up sufficiently to eliminate all looseness. In
+other cases they may be worn enough so that careful
+refitting will be necessary. Where the crank-case is
+divided horizontally into two portions, the upper one
+serving as an engine base to which the cylinders and in
+fact all important working parts are attached, the lower
+portion performs the functions of an oil container and
+cover for the internal mechanism. This is the construction
+generally followed.</p>
+
+<h3><a name="SecXI_14" id="SecXI_14"></a>DEFECTS IN CYLINDERS</h3>
+
+<p>After the cylinders have been removed and stripped
+of all fittings, they should be thoroughly cleaned and then
+carefully examined for defects. The interior or bore
+should be looked at with a view of finding score marks,
+grooves, cuts or scratches in the interior, because there
+are many faults that may be ascribed to depreciation at
+this point. The cylinder bore may be worn out of round,
+which can only be determined by measuring with an internal
+caliper or dial indicator even if the cylinder bore
+shows no sign of wear. The flange at the bottom of the
+cylinder by which it is held to the engine base may be
+cracked. The water jacket wall may have opened up due<span class='pagenum'><a name="Page_417" id="Page_417">[417]</a></span>
+to freezing of the jacket water at some time or other or it
+may be filled with scale and sediment due to the use of
+impure cooling water. The valve seat may be scored or
+pitted, while the threads holding the valve chamber cap
+may be worn so that the cap will not be a tight fit. The
+detachable head construction makes it possible to remove
+that member and obtain ready access to the piston tops
+for scraping out carbon without taking the main cylinder
+portion from the crank-case. When the valves need grinding
+the head may be removed and carried to the bench
+where the work may be performed with absolute assurance
+that none of the valve grinding compound will penetrate
+into the interior of the cylinder as is sometimes unavoidable
+with the I-head cylinder. If the cylinder should be
+scored, the water jacket and combustion head may be
+saved and a new cylinder casting purchased at considerably
+less cost than that of the complete unit cylinder.</p>
+
+<p>The detachable head construction has only recently
+been applied on airplane engines, though it was one of
+the earliest forms of automobile engine construction. In
+the early days it was difficult to procure gaskets or packings
+that would be both gas and water tight. The sheet
+asbestos commonly used was too soft and blew out readily.
+Besides a new gasket had to be made every time
+the cylinder head was removed. Woven wire and asbestos
+packings impregnated with rubber, red lead, graphite and
+other filling materials were more satisfactory than the
+soft sheet asbestos, but were prone to burn out if the
+water supply became low. Materials such as sheet copper
+or brass proved to be too hard to form a sufficiently yielding
+packing medium that would allow for the inevitable
+slight inaccuracies in machining the cylinder head and
+cylinder. The invention of the copper-asbestos gasket,
+which is composed of two sheets of very thin, soft copper
+bound together by a thin edging of the same material
+and having a piece of sheet asbestos interposed solved
+this problem. Copper-asbestos packings form an effective
+seal against leakage of water and a positive retention<span class='pagenum'><a name="Page_418" id="Page_418">[418]</a></span>
+means for keeping the explosion pressure in the
+cylinder. The great advantage of the detachable head is
+that it permits of very easy inspection of the piston tops
+and combustion chamber and ready removal of carbon
+deposits.</p>
+
+<h3><a name="SecXI_15" id="SecXI_15"></a>CARBON DEPOSITS, THEIR CAUSE AND PREVENTION</h3>
+
+<p>Most authorities agree that carbon is the result of
+imperfect combustion of the fuel and air mixture as well
+as the use of lubricating oils of improper flash point.
+Lubricating oils that work by the piston rings may become
+decomposed by the great heat in the combustion
+chamber, but at the same time one cannot blame the lubricating
+oil for all of the carbon deposits. There is little
+reason to suspect that pure petroleum oil of proper body
+will deposit excessive amounts of carbon, though if the
+oil is mixed with castor oil, which is of vegetable origin,
+there would be much carbon left in the interior of the
+combustion chamber. Fuel mixtures that are too rich in
+gasoline also produce these undesirable accumulations.</p>
+
+<p>A very interesting chemical analysis of a sample of
+carbon scraped from the interior of a motor vehicle engine
+shows that ordinarily the lubricant is not as much
+to blame as is commonly supposed. The analysis was
+as follows:</p>
+
+<table class="fsize80" summary="Table p. 418">
+
+<tr>
+<td class="left padr5">Oil</td>
+<td class="right padl5">14.3</td>
+<td class="left">%</td>
+</tr>
+
+<tr>
+<td class="left padr5">Other combustible matter</td>
+<td class="right padl5">17.9</td>
+<td>&nbsp;</td>
+</tr>
+
+<tr>
+<td class="left padr5">Sand, clay, etc.</td>
+<td class="right padl5">24.8</td>
+<td>&nbsp;</td>
+</tr>
+
+<tr>
+<td class="left padr5">Iron oxide</td>
+<td class="right padl5">24.5</td>
+<td>&nbsp;</td>
+</tr>
+
+<tr>
+<td class="left padr5">Carbonate of lime</td>
+<td class="right padl5">8.9</td>
+<td>&nbsp;</td>
+</tr>
+
+<tr>
+<td class="left padr5">Other constituents</td>
+<td class="right padl5">9.6</td>
+<td>&nbsp;</td>
+</tr>
+
+</table>
+
+<p>It is extremely probable that the above could be divided
+into two general classes, these being approximately
+32.2% oil and combustible matter and a much larger
+proportion, or 67.8% of earthy matter. The presence of
+such a large percentage of earthy matter is undoubtedly
+due to the impurities in the air, such as road dust which<span class='pagenum'><a name="Page_419" id="Page_419">[419]</a></span>
+has been sucked in through the carburetor. The fact that
+over 17% of the matter which is combustible was not of
+an oily nature lends strong support to this view. There
+would not be the amount of earthy material present in
+the carbon deposits of an airplane engine as above stated
+because the air is almost free from dust at the high altitudes
+planes are usually flown. One could expect to find
+more combustible and less earthy matter and the carbon
+would be softer and more easily removed. It is very good
+practice to provide a screen on the air intake to reduce
+the amounts of dust sucked in with the air as well as
+observing the proper precautions relative to supplying
+the proper quantities of air to the mixture and of not
+using any more oil than is needed to insure proper lubrication
+of the internal mechanism.</p>
+
+<h3><a name="SecXI_16" id="SecXI_16"></a>USE OF CARBON SCRAPERS</h3>
+
+<p>It is not unusual for one to hear an aviator complain
+that the engine he operates is not as responsive as it was
+when new after he has run it but relatively few hours.
+There does not seem to be anything actually wrong with
+the engine, yet it does not respond readily to the throttle
+and is apt to overheat. While these symptoms denote a
+rundown condition of the mechanism, the trouble is often
+due to nothing more serious than accumulations of carbon.
+The remedy is the removal of this matter out of
+place. The surest way of cleaning the inside of the motor
+thoroughly is to remove the cylinders, if these members
+are cast integrally with the head or of removing the head
+member if that is a separate casting, to expose all parts.</p>
+
+<p>In certain forms of cylinders, especially those of the
+L form, it is possible to introduce simple scrapers down
+through the valve chamber cap holes and through the
+spark-plug hole if this component is placed in the cylinder
+in some position that communicates directly to the
+interior of the cylinder or to the piston top. No claim
+can be made for originality or novelty of this process as<span class='pagenum'><a name="Page_420" id="Page_420">[420]</a></span>
+is has been used for many years on large stationary engines.
+The first step is to dismantle the inlet and exhaust
+piping and remove the valve caps and valves, although
+if the deposit is not extremely hard or present
+in large quantities one can often manipulate the scrapers
+in the valve cap openings without removing either the
+piping or the valves. Commencing with the first cylinder,
+the crank-shaft is turned till the piston is at the top of
+its stroke, then the scraper may be inserted, and the
+operation of removing the carbon started by drawing the
+tool toward the opening. As this is similar to a small
+hoe, the cutting edge will loosen some of the carbon and
+will draw it toward the opening. A swab is made of a
+piece of cloth or waste fastened at the end of a wire and
+well soaked in kerosene to clean out the cylinder.</p>
+
+<p>When available, an electric motor with a length of
+flexible shaft and a small circular cleaning brush having
+wire bristles can be used in the interior of the engine.
+The electric motor need not be over one-eighth horsepower
+running 1,200 to 1,600 R.&nbsp;P.&nbsp;M., and the wire brush
+must, of course, be of such size that it can be easily inserted
+through the valve chamber cap. The flexible shaft
+permits one to reach nearly all parts of the cylinder interior
+without difficulty and the spreading out and flattening
+of the brush insures that considerable surface will be
+covered by that member.</p>
+
+<h3><a name="SecXI_17" id="SecXI_17"></a>BURNING OUT CARBON WITH OXYGEN</h3>
+
+<p>A process of recent development that gives very good
+results in removing carbon without disassembling the
+motor depends on the process of burning out that material
+by supplying oxygen to support the combustion
+and to make it energetic. A number of concerns are already
+offering apparatus to accomplish this work, and in
+fact any shop using an autogenous welding outfit may
+use the oxygen tank and reducing valve in connection
+with a simple special torch for burning the carbon. Results<span class='pagenum'><a name="Page_421" id="Page_421">[421]</a></span>
+have demonstrated that there is little danger of
+damaging the motor parts, and that the cost of oxygen
+and labor is much lower than the old method of removing
+the cylinders and scraping the carbon out, as well as
+being very much quicker than the alternative process of
+using carbon solvent. The only drawback to this system
+is that there is no absolute insurance that every particle
+of carbon will be removed, as small protruding particles
+may be left at points that the flame does not reach and
+cause pre-ignition and consequent pounding, even after
+the oxygen treatment. It is generally known that carbon
+will burn in the presence of oxygen, which supports combustion
+of all materials, and this process takes advantage
+of this fact and causes the gas to be injected into the
+combustion chamber over a flame obtained by a match or
+wax taper.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig182" id="Fig182"></a>
+<img src="images/illo416.png" alt="Fig. 182" width="600" height="354" />
+<p class="caption">Fig. 182.&mdash;Showing Where Carbon Deposits Collect in Engine Combustion
+Chamber, and How to Burn Them Out with the Aid of Oxygen. A&mdash;Special
+Torch. B&mdash;Torch Coupled to Oxygen Tank. C&mdash;Torch in Use.</p></div>
+
+<p>It is suggested by those favoring this process that
+the night before the oxygen is to be used the engine be
+given a conventional kerosene treatment. A half tumbler
+full of this liquid or of denatured alcohol is to be poured<span class='pagenum'><a name="Page_422" id="Page_422">[422]</a></span>
+into each cylinder and permitted to remain there over
+night. As a precaution against fire, the gasoline is shut
+off from the carburetor before the torch is inserted in
+the cylinder and the motor started so that the gasoline in
+the pipe and carburetor float chamber will be consumed.
+Work is done on one cylinder at a time. A note of caution
+was recently sounded by a prominent spark-plug
+manufacturer recommending that the igniter member be
+removed from the cylinder in order not to injure it by
+the heat developed. The outfits on the market consist
+of a special torch having a trigger controlled valve and
+a length of flexible tubing such as shown at <a href="#Fig182">Fig. 182</a>, A,
+and a regulating valve and oxygen tank as shown at B.
+The gauge should be made to register about twelve
+pounds pressure.</p>
+
+<p>The method of operation is very simple and is outlined
+at C. The burner tube is placed in the cylinder and
+the trigger valve is opened and the oxygen permitted to
+circulate in the combustion chamber. A lighted match
+or wax taper is dropped in the chamber and the injector
+tube is moved around as much as possible so as to cover
+a large area. The carbon takes fire and burns briskly in
+the presence of the oxygen. The combustion of the carbon
+is accompanied by sparks and sometimes by flame if
+the deposit is of an oily nature. Once the carbon begins
+to burn the combustion continues without interruption as
+long as the oxygen flows into the cylinder. Full instructions
+accompany each outfit and the amount of pressure
+for which the regulator should be set depends upon the
+design of the torch and the amount of oxygen contained
+in the storage tank.</p>
+
+<h3><a name="SecXI_18" id="SecXI_18"></a>REPAIRING SCORED CYLINDERS</h3>
+
+<p>If the engine has been run at any time without adequate
+lubrication, one or more of the cylinders may be
+found to have vertical scratches running up and down
+the cylinder walls. The depth of these will vary according<span class='pagenum'><a name="Page_423" id="Page_423">[423]</a></span>
+to the amount of time the cylinder was without lubrication,
+and if the grooves are very deep the only remedy
+is to purchase a new member. Of course, if sufficient
+stock is available in the cylinder walls, the cylinders may
+be rebored and new pistons which are oversize, <i>i.e.</i>, larger
+than standard, may be fitted. Where the scratches are
+not deep they may be ground out with a high speed emery
+wheel or lapped out if that type of machine is not available.
+Wrist pins have been known to come loose, especially
+when these are retained by set screws that are not
+properly locked, and as wrist-pins are usually of hardened
+steel it will be evident that the sharp edge of that
+member can act as a cutting tool and make a pronounced
+groove in the cylinder. Cylinder grinding is a job that
+requires skilled mechanics, but may be accomplished on
+any lathe fitted with an internal grinding attachment.
+While automobile engine cylinders usually have sufficient
+wall thickness to stand reboring, those of airplane engines
+seldom have sufficient metal to permit of enlarging the
+bore very much by a boring tool. A few thousandths of
+an inch may be ground out without danger, however.
+An airplane engine cylinder with deep grooves must be
+scrapped as a general rule.</p>
+
+<p>Where the grooves in the cylinder are not deep or
+where it has warped enough so the rings do not bear
+equally at all parts of the cylinder bore, it is possible to
+obtain a fairly accurate degree of finish by a lapping process
+in which an old piston is coated with a mixture of
+fine emery and oil and is reciprocated up and down in the
+cylinder as well as turned at the same time. This may
+be easily done by using a dummy connecting rod having
+only a wrist pin end boss, and of such size at the other
+end so that it can be held in the chuck of a drill press.
+The cylinder casting is firmly clamped on the drill press
+table by suitable clamping blocks, and a wooden block is
+placed in the combustion chamber to provide a stop for
+the piston at its lower extreme position. The back gears
+are put in and the drill chuck is revolved slowly. All the<span class='pagenum'><a name="Page_424" id="Page_424">[424]</a></span>
+while that the piston is turning the drill chuck should be
+raised up and down by the hand feed lever, as the best
+results are obtained when the lapping member is given
+a combination of rotary and reciprocating motion.</p>
+
+<h3><a name="SecXI_19" id="SecXI_19"></a>VALVE REMOVAL AND INSPECTION</h3>
+
+<p>One of the most important parts of the gasoline engine
+and one that requires frequent inspection and refitting
+to keep in condition, is the mushroom or poppet valve
+that controls the inlet and exhaust gas flow. In overhauling
+it is essential that these valves be removed from
+their seatings and examined carefully for various defects
+which will be enumerated at proper time. The problem
+that concerns us now is the best method of removing the
+valve. These are held against the seating in the cylinder
+by a coil spring which exerts its pressure on the cylinder
+casting at the upper end and against a suitable collar
+held by a key at the lower end of the valve stem. In
+order to remove the valve it is necessary to first compress
+the spring by raising the collar and pulling the
+retaining key out of the valve stem. Many forms of valve
+spring lifters have been designed to permit ready removal
+of the valves.</p>
+
+<p>When the cylinder is of the valve in-the-head form,
+the method of valve removal will depend entirely upon
+the system of cylinder construction followed. In the
+Sturtevant cylinder design it is possible to remove the
+head from the cylinder castings and the valve springs
+may be easily compressed by any suitable means when
+the cylinder head is placed on the work bench where it
+can be easily worked on. The usual method is to place
+the head on a soft cloth with the valves bearing against
+the bench. The valve springs may then be easily pushed
+down with a simple forked lever and the valve stem key
+removed to release the valve spring collar. In the Curtiss
+OX-2 (see <a href="#Fig182a">Fig. 182<sup>1</sup>&#8260;<sub>2</sub></a>) and Hall-Scott engines it is not
+possible to remove the valves without taking the cylinder<span class='pagenum'><a name="Page_425" id="Page_425">[425]</a></span>
+off the crank-case, because the valve seats are machined
+directly in the cylinder head and the valve domes are cast
+integrally with the cylinder. This means that if the valves
+need grinding the cylinder must be removed from the
+engine base to provide access to the valve heads which
+are inside of that member, and which cannot be reached
+from the outside as is true of the L-cylinder construction.
+In the Curtiss VX engines, the valves are carried in detachable
+cages which may be removed when the valves
+need attention.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig182a" id="Fig182a"></a>
+<img src="images/illo420.jpg" alt="Fig. 182-1/2" width="450" height="410" />
+<p class="caption">Fig. 182<sup>1</sup>&#8260;<sub>2</sub>.&mdash;Part
+Sectional View, Showing Valve Arrangement in Cylinder
+of Curtiss OX-2 Aviation Engine.</p></div>
+
+<h3><a name="SecXI_20" id="SecXI_20"></a>RESEATING AND TRUING VALVES</h3>
+
+<p>Much has been said relative to valve grinding, and
+despite the mass of information given in the trade prints<span class='pagenum'><a name="Page_426" id="Page_426">[426]</a></span>
+it is rather amusing to watch the average repairman or the
+engine user who prides himself on maintaining his own
+motor performing this essential operation. The common
+mistakes are attempting to seat a badly grooved or pitted
+valve head on an equally bad seat, which is an almost
+hopeless job, and of using coarse emery and bearing down
+with all one&#8217;s weight on the grinding tool with the hope
+of quickly wearing away the rough surfaces. The use of
+improper abrasive material is a fertile cause of failure
+to obtain a satisfactory seating. Valve grinding is not a
+difficult operation if certain precautions are taken before
+undertaking the work. The most important of these is
+to ascertain if the valve head or seat is badly scored or
+pitted. If such is found to be the case no ordinary
+amount of grinding will serve to restore the surfaces. In
+this event the best thing to do is to remove the valve
+from its seating and to smooth down both the valve head
+and the seat in the cylinder before attempt is made to
+fit them together by grinding. Another important precaution
+is to make sure that the valve stem is straight,
+and that the head is not warped out of shape.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig183" id="Fig183"></a>
+<img src="images/illo422.jpg" alt="Fig. 183" width="400" height="535" />
+<p class="caption">Fig. 183.&mdash;Tools for Restoring Valve Head and Seats.</p></div>
+
+<p>A number of simple tools is available at the present
+time for reseating valves, these being outlined at <a href="#Fig183">Fig.
+183</a>. That shown at A is a simple fixture for facing off
+the valve head. The stem is supported by suitable bearings
+carried by the body or shank of the tool, and the
+head is turned against an angularly disposed cutter which
+is set for the proper valve seat angle. The valve head
+is turned by a screw-driver, the amount of stock removed
+from the head depending upon the location of the adjusting
+screw. Care must be taken not to remove too much
+metal, only enough being taken off to remove the most
+of the roughness. Valves are made in two standard
+tapers, the angle being either 45 or 60 degrees. It is imperative
+that the cutter blade be set correctly in order
+that the bevel is not changed. A set of valve truing and
+valve-seat reaming cutters is shown at <a href="#Fig183">Fig. 183</a>, B. This
+is adaptable to various size valve heads, as the cutter<span class='pagenum'><a name="Page_427" id="Page_427">[427]</a></span>
+blade D may be moved to correspond to the size of the
+valve head being trued up. These cutter blades are made
+of tool steel and have a bevel at each end, one at 45 degrees,
+the other at 60 degrees. The valve seat reamer
+shown at G will take any one of the heads shown at F.<span class='pagenum'><a name="Page_428" id="Page_428">[428]</a></span>
+It will also take any one of the guide bars shown at H.
+The function of the guide bars is to fit the valve stem
+bearing in order to locate the reamer accurately and to
+insure that the valve seat is machined concentrically with
+its normal center. Another form of valve seat reamer
+and a special wrench used to turn it is shown at C. The
+valve head truer shown at <a href="#Fig183">Fig. 183</a>, D, is intended to be
+placed in a vise and is adaptable to a variety of valve
+head sizes. The smaller valves merely fit deeper in the
+conical depression. The cutter blade is adjustable and
+the valve stem is supported by a simple self-centering
+bearing. In operation it is intended that the valve stem,
+which protrudes through the lower portion of the guide
+bearing, shall be turned by a drill press or bit stock while
+the valve head is set against the cutter by pressure of a
+pad carried at the end of a feed screw which is supported
+by a hinged bridge member. This can be swung out of
+place as indicated to permit placing the valve head against
+the cutter or removing it.</p>
+
+<p>As the sizes of valve heads and stems vary considerably
+a &#8220;Universal&#8221; valve head truing tool must have
+some simple means of centering the valve stem in order
+to insure concentric machining of the valve head. A valve
+head truer which employs an ingenious method of guiding
+the valve stem is shown at <a href="#Fig183">Fig. 183</a>, E. The device
+consists of a body portion, B, provided with an external
+thread at the top on which the cutter head, A, is screwed.
+A number of steel balls, C, are carried in the grooves
+which may be altered in size by the adjustment nut, F,
+which screws in the bottom of the body portion, B. As
+the nut F is screwed in against the spacer member E,
+the V-grooves are reduced in size and the steel balls, C,
+are pressed out in contact with the valve stem. As the
+circle or annulus is filled with balls in both upper and
+lower portions the stem may be readily turned because
+it is virtually supported by ball bearing guides. When
+a larger valve stem is to be supported, the adjusting nut
+F, is screwed out which increases the size of the grooves<span class='pagenum'><a name="Page_429" id="Page_429">[429]</a></span>
+and permits the balls, C, to spread out and allow the larger
+stem to be inserted.</p>
+
+<h3><a name="SecXI_21" id="SecXI_21"></a>VALVE GRINDING PROCESSES</h3>
+
+<p>Mention has been previously made of the importance
+of truing both valve head and seat before attempt is made
+to refit the parts by grinding. After smoothing the valve
+seat the next step is to find some way of turning the valve.
+Valve heads are usually provided with a screw-driver slot
+passing through the boss at the top of the valve or with
+two drilled holes to take a forked grinding tool. A combination
+grinding tool has been devised which may be
+used when either the two drilled holes or the slotted head
+form of valve is to be rotated. This consists of a special
+form of screw driver having an enlarged boss just above
+the blade, this boss serving to support a U-shape piece
+which can be securely held in operative position by the
+clamp screw or which can be turned out of the way if
+the screw driver blade is to be used.</p>
+
+<p>As it is desirable to turn the valve through a portion
+of a revolution and back again rather than turning it
+always in the same direction, a number of special tools
+has been designed to make this oscillating motion possible
+without trouble. A simple valve grinding tool is shown
+at <a href="#Fig184">Fig. 184</a>, C. This consists of a screw-driver blade
+mounted in a handle in such a way that the end may
+turn freely in the handle. A pinion is securely fastened
+to the screw-driver blade shank, and is adapted to fit a
+race provided with a wood handle and guided by a bent
+bearing member securely fastened to the screw-driver
+handle. As the rack is pushed back and forth the pinion
+must be turned first in one direction and then in the other.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig184" id="Fig184"></a>
+<img src="images/illo425.png" alt="Fig. 184" width="450" height="594" />
+<p class="caption">Fig. 184.&mdash;Tools and Processes Utilized in Valve Grinding.</p></div>
+
+<p>A valve grinding tool patterned largely after a breast
+drill is shown at <a href="#Fig184">Fig. 184</a>, D. This is worked in such a
+manner that a continuous rotation of the operating crank
+will result in an oscillating movement of the chuck carrying
+the screw-driver blade. The bevel pinions which are<span class='pagenum'><a name="Page_430" id="Page_430">[430]</a></span>
+used to turn the chuck are normally free unless clutched
+to the chuck stem by the sliding sleeve which must turn
+with the chuck stem and which carries clutching members
+at each end to engage similar members on the bevel pinions
+and lock these to the chuck stem, one at a time. The
+bevel gear carries a cam-piece which moves the clutch<span class='pagenum'><a name="Page_431" id="Page_431">[431]</a></span>
+sleeve back and forth as it revolves. This means that the
+pinion giving forward motion of the chuck is clutched to
+the chuck spindle for a portion of a revolution of the
+gear and clutch sleeve is moved back by the cam and
+clutched to the pinion giving a reverse motion of the
+chuck during the remainder of the main drive gear revolution.</p>
+
+<p>It sometimes happens that the adjusting screw on the
+valve lift plunger or the valve lift plunger itself when
+L head cylinders are used does not permit the valve head
+to rest against the seat. It will be apparent that unless
+a definite space exists between the end of the valve stem
+and the valve lift plunger that grinding will be of little
+avail because the valve head will not bear properly
+against the abrasive material smeared on the valve seat.</p>
+
+<p>The usual methods of valve grinding are clearly outlined
+at <a href="#Fig184">Fig. 184</a>. The view at the left shows the method
+of turning the valve by an ordinary screw driver and also
+shows a valve head at A, having both the drilled holes
+and the screw-driver slot for turning the member and two
+special forms of fork-end valve grinding tools. In the
+sectional view shown at the right, the use of the light
+spring between the valve head and the bottom of the valve
+chamber to lift the valve head from the seat whenever
+pressure on the grinding tool is released is clearly indicated.
+It will be noted also that a ball of waste or cloth
+is interposed in the passage between the valve chamber
+and the cylinder interior to prevent the abrasive material
+from passing into the cylinder from the valve chamber.
+When a bitstock is used, instead of being given a true
+rotary motion the chuck is merely oscillated through the
+greater part of the circle and back again. It is necessary
+to lift the valve from its seat frequently as the grinding
+operation continues; this is to provide an even distribution
+of the abrasive material placed between the valve
+head and its seat. Only sufficient pressure is given to
+the bitstock to overcome the uplift of the spring and to
+insure that the valve will be held against the seat. Where<span class='pagenum'><a name="Page_432" id="Page_432">[432]</a></span>
+the spring is not used it is possible to raise the valve
+from time to time with the hand which is placed under
+the valve stem to raise it as the grinding is carried on.
+It is not always possible to lift the valve in this manner
+when the cylinders are in place on the engine base owing
+to the space between the valve lift plunger and the end
+of the valve stem. In this event the use of the spring as
+shown in sectional view will be desirable.</p>
+
+<p>The abrasive generally used is a paste made of
+medium or fine emery and lard oil or kerosene. This is
+used until the surfaces are comparatively smooth, after
+which the final polish or finish is given with a paste of
+flour emery, grindstone dust, crocus, or ground glass and
+oil. An erroneous impression prevails in some quarters
+that the valve head surface and the seating must have
+a mirror-like polish. While this is not necessary it is
+essential that the seat in the cylinder and the bevel surface
+of the head be smooth and free from pits or scratches
+at the completion of the operation. All traces of the
+emery and oil should be thoroughly washed out of the
+valve chamber with gasoline before the valve mechanism
+is assembled and in fact it is advisable to remove the old
+grinding compound at regular intervals, wash the seat
+thoroughly and supply fresh material as the process is in
+progress.</p>
+
+<p>The truth of seatings may be tested by taking some
+Prussian blue pigment and spreading a thin film of it
+over the valve seat. The valve is dropped in place and
+is given about one-eighth turn with a little pressure on
+the tool. If the seating is good both valve head and seat
+will be covered uniformly with color. If high spots exist,
+the heavy deposit of color will show these while the low
+spots will be made evident because of the lack of pigment.
+The grinding process should be continued until
+the test shows an even bearing of the valve head at all
+points of the cylinder seating. When the valves are held
+in cages it is possible to catch the cage in a vise and to
+turn the valve in any of the ways indicated. It is much<span class='pagenum'><a name="Page_433" id="Page_433">[433]</a></span>
+easier to clean off the emery and oil and there is absolutely
+no danger of getting the abrasive material in the
+cylinder if the construction is such that the valve cage
+or cylinder head member carrying the valve can be removed
+from the cylinder. When valves are held in cages,
+the tightness of the seat may be tested by partially filling
+the cage with gasoline and noticing how much liquid oozes
+out around the valve head. The degree of moisture present
+indicates the efficacy of the grinding process.</p>
+
+<p>The valves of Curtiss OX-2 cylinders are easily
+ground in by using a simple fixture or tool and working
+from the top of the cylinder instead of from the inside.
+A tube having a bore just large enough to go over the
+valve stem is provided with a wooden handle or taped at
+one end and a hole of the same size as that drilled through
+the valve stem is put in at the other. To use, the open
+end of the tube is pushed over the valve stem and a split
+pin pushed through the tube and stem. The valve may
+be easily manipulated and ground in place by oscillating
+in the customary manner.</p>
+
+<h3><a name="SecXI_22" id="SecXI_22"></a>DEPRECIATION IN VALVE OPERATING SYSTEMS</h3>
+
+<p>There are a number of points to be watched in the
+valve operating system because valve timing may be seriously
+interfered with if there is much lost motion at the
+various bearing points in the valve lift mechanism. The
+two conventional methods of opening valves are shown at
+<a href="#Fig185">Fig. 185</a>. That at A is the type employed when the valve
+cages are mounted directly in the head, while the form at
+B is the system used when the valves are located in a
+pocket or extension of the cylinder casting as is the case
+if an L, or T-head cylinder is used. It will be evident
+that there are several points where depreciation may take
+place. The simplest form is that shown at B, and even on
+this there are five points where lost motion may be noted.
+The periphery of the valve opening cam or roller may be
+worn, though this is not likely unless the roller or cam has<span class='pagenum'><a name="Page_434" id="Page_434">[434]</a></span>
+been inadvertently left soft. The pin which acts as a
+bearing for the roller may become worn, this occurring
+quite often. Looseness may materialize between the bearing
+surfaces of the valve lift plunger and the plunger
+guide casting, and there may also be excessive clearance
+between the top of the plunger and the valve stem.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig185" id="Fig185"></a>
+<img src="images/illo429.png" alt="Fig. 185" width="400" height="442" />
+<p class="caption">Fig. 185.&mdash;Outlining Points in Valve Operating Mechanism Where Depreciation
+is Apt to Exist.</p></div>
+
+<p>On the form shown at A, there are several parts added
+to those indicated at B. A walking beam or rocker lever
+is necessary to transform the upward motion of the tappet
+rod to a downward motion of the valve stem. The pin<span class='pagenum'><a name="Page_435" id="Page_435">[435]</a></span>
+on which this member fulcrums may wear as will also the
+other pin acting as a hinge or bearing for the yoke end
+of the tappet rod. It will be apparent that if slight play
+existed at each of the points mentioned it might result in
+a serious diminution of valve opening. Suppose, for example,
+that there were .005-inch lost motion at each of
+three bearing points, the total lost motion would be .015-inch
+or sufficient to produce noisy action of the valve
+mechanism. When valve plungers of the adjustable form,
+such as shown at B, are used, the hardened bolt head in
+contact with the end of the valve stem may become hollowed
+out on account of the hammering action at that
+point. It is imperative that the top of this member be
+ground off true and the clearance between the valve stem
+and plunger properly adjusted. If the plunger is a non-adjustable
+type it will be necessary to lengthen the valve
+stem by some means in order to reduce the excessive
+clearance. The only remedy for wear at the various
+hinges and bearing pins is to bore the holes out slightly
+larger and to fit new hardened steel pins of larger diameter.
+Depreciation between the valve plunger guide and
+the valve plunger is usually remedied by fitting new
+plunger guides in place of the worn ones. If there is
+sufficient stock in the plunger guide casting as is sometimes
+the case when these members are not separable from
+the cylinder casting, the guide may be bored out and
+bushed with a light bronze bushing.</p>
+
+<p>A common cause of irregular engine operation is due to
+a sticking valve. This may be owing to a bent valve stem,
+a weak or broken valve spring or an accumulation of
+burnt or gummed oil between the valve stem and the
+valve stem guide. In order to prevent this the valve stem
+must be smoothed with fine emery cloth and no burrs or
+shoulders allowed to remain on it, and the stem must also
+be straight and at right angles to the valve head. If the
+spring is weak it may be strengthened in some cases by
+stretching it out after annealing so that a larger space
+will exist between the coils and re-hardening. Obviously<span class='pagenum'><a name="Page_436" id="Page_436">[436]</a></span>
+if a spring is broken the only remedy is replacement of
+the defective member.</p>
+
+<p>Mention has been made of wear in the valve stem
+guide and its influence on engine action. When these
+members are an integral part of the cylinder the only
+method of compensating for this wear is to drill the guide
+out and fit a bushing, which may be made of steel tube.</p>
+
+<p>In some engines, especially those of recent development,
+the valve stem guide is driven or screwed into the
+cylinder casting and is a separate member which may be
+removed when worn and replaced with a new one. When
+the guides become enlarged to such a point that considerable
+play exists between them and the valve stems,
+they may be easily knocked out or unscrewed.</p>
+
+<h3><a name="SecXI_23" id="SecXI_23"></a>PISTON TROUBLES</h3>
+
+<p>If an engine has been entirely dismantled it is very
+easy to examine the pistons for deterioration. While it
+is important that the piston be a good fit in the cylinder
+it is mainly upon the piston rings that compression depends.
+The piston should fit the cylinder with but little
+looseness, the usual practice being to have the piston
+about .001-inch smaller than the bore for each inch of
+piston diameter at the point where the least heat is present
+or at the bottom of the piston. It is necessary to
+allow more than this at the top of the piston owing to its
+expansion due to the direct heat of the explosion. The
+clearance is usually graduated and a piston that would be
+.005-inch smaller than the cylinder bore at the bottom
+would be about .0065-inch at the middle and .0075-inch at
+the top. If much more play than this is evidenced the
+piston will &#8220;slap&#8221; in the cylinder and the piston will be
+worn at the ends more than in the center. Aluminum or
+alloy pistons require more clearance than cast iron ones
+do, usually 1.50 times as much. Pistons sometimes warp
+out of shape and are not truly cylindrical. This results
+in the high spots rubbing on the cylinder while the low<span class='pagenum'><a name="Page_437" id="Page_437">[437]</a></span>
+spots will be blackened where a certain amount of gas
+has leaked by.</p>
+
+<p>Mention has been previously made of the necessity of
+reboring or regrinding a cylinder that has become scored
+or scratched and which allows the gas to leak by the
+piston rings. When the cylinder is ground out, it is necessary
+to use a larger piston to conform to the enlarged
+cylinder bore. Most manufacturers are prepared to furnish
+over-size pistons, there being four standard over-size
+dimensions adopted by the S. A. E. for rebored
+cylinders. These are .010-inch, .020-inch, .030-inch, and
+.040-inch larger than the original bore.</p>
+
+<p>The piston rings should be taken out of the piston
+grooves and all carbon deposits removed from the inside
+of the ring and the bottom of the groove. It is important
+to take this deposit out because it prevents the rings
+from performing their proper functions by reducing the
+ring elasticity, and if the deposit is allowed to accumulate
+it may eventually result in sticking and binding of the
+ring, this producing excessive friction or loss of compression.
+When the rings are removed they should be tested
+to see if they retain their elasticity and it is also well to
+see that the small pins in some pistons which keep the
+rings from turning around so the joints will not come in
+line are still in place. If no pins are found there is no
+cause for alarm because these dowels are not always
+used. When fitted, they are utilized with rings having a
+butt joint or diagonal cut as the superior gas retaining
+qualities of the lap or step joint render the pins unnecessary.</p>
+
+<p>If gas has been blowing by the ring or if these members
+have not been fitting the cylinder properly the points
+where the gas passed will be evidenced by burnt, brown
+or roughened portions of the polished surface of the
+pistons and rings. The point where this discoloration
+will be noticed more often is at the thin end of an eccentric
+ring, the discoloration being present for about <sup>1</sup>&#8260;<sub>2</sub>-inch
+or <sup>3</sup>&#8260;<sub>4</sub>-inch each side of the slot. It may be possible
+that<span class='pagenum'><a name="Page_438" id="Page_438">[438]</a></span>
+the rings were not true when first put in. This made it
+possible for the gas to leak by in small amounts initially
+which increased due to continued pressure until quite a
+large area for gas escape had been created.</p>
+
+<h3><a name="SecXI_24" id="SecXI_24"></a>PISTON RING MANIPULATION</h3>
+
+<p>Removing piston rings without breaking them is a difficult
+operation if the proper means are not taken, but is
+a comparatively simple one when the trick is known. The
+tools required are very simple, being three strips of thin
+steel about one-quarter inch wide and four or five inches
+long and a pair of spreading tongs made up of one-quarter
+inch diameter keystock tied in the center with a
+copper wire to form a hinge. The construction is such
+that when the hand is closed and the handles brought together
+the other end of the expander spreads out, an
+action just opposite to that of the conventional pliers.
+The method of using the tongs and the metal strips is
+clearly indicated at <a href="#Fig186">Fig. 186</a>. At A the ring expander is
+shown spreading the ends of the rings sufficiently to insert
+the pieces of sheet metal between one of the rings and the
+piston. Grasp the ring as shown at B, pressing with the
+thumbs on the top of the piston and the ring will slide off
+easily, the thin metal strips acting as guide members to
+prevent the ring from catching in the other piston grooves.
+Usually no difficulty is experienced in removing the top
+or bottom rings, as these members may be easily expanded
+and worked off directly without the use of a metal strip.
+When removing the intermediate rings, however, the metal
+strips will be found very useful. These are usually made
+by the repairman by grinding the teeth from old hacksaw
+blades and rounding the edges and corners in order to reduce
+the liability of cutting the fingers. By the use of the
+three metal strips a ring is removed without breaking or
+distorting it and practically no time is consumed in the
+operation.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig186" id="Fig186"></a>
+<img src="images/illo435.png" alt="Fig. 186" width="400" height="463" />
+<p class="caption">Fig. 186.&mdash;Method of Removing Piston Rings, and Simple Clamp to Facilitate
+Insertion of Rings in Cylinder.</p></div>
+
+<p class='pagenum'><a name="Page_439" id="Page_439">[439]</a></p>
+
+<h3><a name="SecXI_25" id="SecXI_25"></a>FITTING PISTON RINGS</h3>
+
+<p>Before installing new rings, they should be carefully
+fitted to the grooves to which they are applied. The tools
+required are a large piece of fine emery cloth, a thin, flat
+file, a small vise with copper or leaden jaw clips, and a
+smooth hard surface such as that afforded by the top of
+a surface plate or a well planed piece of hard wood. After
+making sure that all deposits of burnt oil and carbon have
+been removed from the piston grooves, three rings are
+selected, one for each groove. The ring is turned all
+around its circumference into the groove it is to fit, which
+can be done without springing it over the piston as the
+outside edge of the ring may be used to test the width of
+the groove just as well as the inside edge. The ring should
+be a fair fit and while free to move circumferentially there
+should be no appreciable up and down motion. If the
+ring is a tight fit it should be laid edge down upon the
+piece of emery cloth which is placed on the surface plate
+and carefully rubbed down until it fits the groove it is to
+occupy. It is advisable to fit each piston ring individually
+and to mark them in some way to insure that they will be
+placed in the groove to which they are fitted.</p>
+
+<p>The repairman next turns his attention to fitting the
+ring in the cylinder itself. The ring should be pushed
+into the cylinder at least two inches up from the bottom
+and endeavor should be made to have the lower edge of
+the ring parallel with the bottom of the cylinder. If the
+ring is not of correct diameter, but is slightly larger than
+the cylinder bore, this condition will be evident by the
+angular slots of the rings being out of line or by difficulty
+in inserting the ring if it is a lap joint form. If such is
+the case the ring is removed from the cylinder and placed
+in the vise between soft metal jaw clips. Sufficient metal
+is removed with a fine file from the edges of the ring at
+the slot until the edges come into line and a slight space
+exists between them when the ring is placed into the cylinder.
+It is important that this space be left between the<span class='pagenum'><a name="Page_440" id="Page_440">[440]</a></span>
+ends, for if this is not done when the ring becomes heated
+the expansion of metal may cause the ends to abut and
+the ring to jam in the cylinder.</p>
+
+<p>It is necessary to use more than ordinary caution in
+replacing the rings on the piston because they are usually
+made of cast iron, a metal that is very fragile and liable
+to break because of its brittleness. Special care should
+be taken in replacing new rings as these members are<span class='pagenum'><a name="Page_441" id="Page_441">[441]</a></span>
+more apt to break than old ones. This is probably accounted
+for by the heating action on used rings which
+tends to anneal the metal as well as making it less springy.
+The bottom ring should be placed in position first which
+is easily accomplished by springing the ring open enough
+to pass on the piston and then sliding it into place in the
+lower groove which on some types of engines is below
+the wrist pin, whereas in others all grooves are above that
+member. The other members are put in by a reversal of
+the process outlined at <a href="#Fig186">Fig. 186</a>, A and B. It is not always
+necessary to use the guiding strips of metal when replacing
+rings as it is often possible, by putting the rings on
+the piston a little askew and maneuvering them to pass
+the grooves without springing the ring into them. The
+top ring should be the last one placed in position.</p>
+
+<p>Before placing pistons in the cylinder one should make
+sure that the slots in the piston rings are spaced equidistant
+on the piston, and if pins are used to keep the ring
+from turning one should be careful to make sure that these
+pins fit into their holes in the ring and that they are not
+under the ring at any point. Practically all cylinders are
+chamfered at the lower end to make insertion of piston
+rings easier. The operation of putting on a cylinder casting
+over a piston really requires two pairs of hands, one
+to manipulate the cylinder, the other person to close the
+rings as they enter the cylinder. This may be done very
+easily by a simple clamp member made of sheet brass or
+iron and used to close the ring as indicated at <a href="#Fig186">Fig. 186</a>, C.
+It is apparent that the clamp must be adjusted to each
+individual ring and that the split portion of the clamp
+must coincide with the split portion of the ring. The
+cylinder should be well oiled before any attempt is made to
+install the pistons. The engine should be run with more
+than the ordinary amount of lubricant for several hours
+after new piston rings have been inserted. On first starting
+the engine, one may be disappointed in that the compression
+is even less than that obtained with the old rings.
+This condition will soon be remedied as the rings become<span class='pagenum'><a name="Page_442" id="Page_442">[442]</a></span>
+polished and adapt themselves to the contour of the
+cylinder.</p>
+
+<h3><a name="SecXI_26" id="SecXI_26"></a>WRIST PIN WEAR</h3>
+
+<p>While wrist pins are usually made of very tough steel,
+case hardened with the object of wearing out an easily
+renewable bronze bushing in the upper end of the connecting
+rod rather than the wrist pin it sometimes happens
+that these members will be worn so that even the replacement
+of a new bushing in the connecting rod will
+not reduce the lost motion and attendant noise due to a
+loose wrist pin. The only remedy is to fit new wrist pins
+to the piston. Where the connecting rod is clamped to
+the wrist pin and that member oscillates in the piston
+bosses the wear will usually be indicated on bronze bushings
+which are pressed into the piston bosses. These are
+easily renewed and after running a reamer through them
+of the proper size no difficulty should be experienced in
+replacing either the old or a new wrist pin depending
+upon the condition of that member. If no bushings are
+provided, as in alloy pistons, the bosses can sometimes
+be bored out and thin bushings inserted, though this is
+not always possible. The alternative is to ream out the
+bosses and upper end of rod a trifle larger after holes are
+trued up and fit oversize wrist pins.</p>
+
+<h3><a name="SecXI_27" id="SecXI_27"></a>INSPECTION AND REFITTING OF ENGINE BEARINGS</h3>
+
+<p>While the engine is dismantled one has an excellent
+opportunity to examine the various bearing points in the
+engine crank-case to ascertain if any looseness exists due
+to depreciation of the bearing surfaces. As will be evident,
+both main crank-shaft bearings and the lower end
+of the connecting rods may be easily examined for deterioration.
+With the rods in place, it is not difficult to
+feel the amount of lost motion by grasping the connecting
+rod firmly with the hand and moving it up and down.
+After the connecting rods have been removed and the<span class='pagenum'><a name="Page_443" id="Page_443">[443]</a></span>
+propeller hub taken off the crank-shaft to permit of ready
+handling, any looseness in the main bearing may be detected
+by lifting up on either the front or rear end of
+the crank-shaft and observing if there is any lost motion
+between the shaft journal and the main bearing caps.
+It is not necessary to take an engine entirely apart to
+examine the main bearings, as in most forms these may be
+readily reached by removing the sump. The symptoms
+of worn main bearings are not hard to identify. If an
+engine knocks regardless of speed or spark-lever position,
+and the trouble is not due to carbon deposits in the combustion
+chamber, one may reasonably surmise that the
+main bearings have become loose or that lost motion may
+exist at the connecting rod big ends, and possibly at the
+wrist pins. The main journals of any well resigned engine
+are usually proportioned with ample surface and
+will not wear unduly unless lubrication has been neglected.
+The connecting rod bearings wear quicker than
+the main bearings owing to being subjected to a greater
+unit stress, and it may be necessary to take these up.</p>
+
+<p class='pagenum' style="margin-top: -1.5em;"><a name="Page_444" id="Page_444">[444]</a></p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig187" id="Fig187"></a>
+<img src="images/illo439.png" alt="Fig. 187" width="350" height="587" />
+<p class="caption">Fig. 187.&mdash;Tools and Processes Used in Refitting Engine Bearings.</p></div>
+
+<h3>ADJUSTING MAIN BEARINGS</h3>
+
+<p>When the bearings are not worn enough to require
+refitting the lost motion can often be eliminated by removing
+one or more of the thin shims or liners ordinarily
+used to separate the bearing caps from the seat. These
+are shown at <a href="#Fig187">Fig. 187</a>, A. Care must be taken that an
+even number of shims of the same thickness are removed
+from each side of the journal. If there is considerable
+lost motion after one or two shims have been removed,
+it will be advisable to take out more shims and to scrape
+the bearing to a fit before the bearing cap is tightened
+up. It may be necessary to clean up the crank-shaft
+journals as these may be scored due to not having received
+clean oil or having had bearings seize upon them.
+It is not difficult to true up the crank-pins or main journals
+if the score marks are not deep. A fine file and<span class='pagenum'><a name="Page_445" id="Page_445">[445]</a></span>
+emery cloth may be used, or a lapping tool such as depicted
+at <a href="#Fig187">Fig. 187</a>, B. The latter is preferable because
+the file and emery cloth will only tend to smooth the surface
+while the lap will have the effect of restoring the
+crank to proper contour.</p>
+
+<p>A lapping tool may be easily made, as shown at B, the
+blocks being of lead or hard wood. As the width of these
+are about half that of the crank-pin the tool may be
+worked from side to side as it is rotated. An abrasive
+paste composed of fine emery powder and oil is placed
+between the blocks, and the blocks are firmly clamped to
+the crank-pin. As the lead blocks bed down, the wing
+nut should be tightened to insure that the abrasive will be
+held with some degree of pressure against the shaft. A
+liberal supply of new abrading material is placed between
+the lapping blocks and crank-shaft from time to time and
+the old mixture cleaned off with gasoline. It is necessary
+to maintain a side to side movement of the lapping tool
+in order to have the process affect the whole width of the
+crank-pin equally. The lapping is continued until a
+smooth surface is obtained. If a crank-pin is worn out
+of true to any extent the only method of restoring it is
+to have it ground down to proper circular form by a
+competent mechanic having the necessary machine tools
+to carry on the work accurately. A crank-pin truing
+tool that may be worked by hand is shown at <a href="#Fig187">Fig. 187</a>, K.</p>
+
+<p>After the crank-shaft is trued the next operation is to
+fit it to the main bearings or rather to scrape these members
+to fit the shaft journal. In order to bring the brasses
+closer together, it may be necessary to remove a little
+metal from the edges of the caps to compensate for the
+lost motion. A very simple way of doing this is shown
+at <a href="#Fig187">Fig. 187</a>, D. A piece of medium emery cloth is rested
+on the surface plate and the box or brass is pushed back
+and forth over that member by hand, the amount of pressure
+and rapidity of movement being determined by the
+amount of metal it is necessary to remove. This is better
+than filing, because the edges will be flat and there will be<span class='pagenum'><a name="Page_446" id="Page_446">[446]</a></span>
+no tendency for the bearing caps to rock when placed
+against the bearing seat. It is important to take enough
+off the edges of the boxes to insure that they will grip
+the crank tightly. The outer diameter must be checked
+with a pair of calipers during this operation to make sure
+that the surfaces remain parallel. Otherwise, the bearing
+brasses will only grip at one end and with such insufficient
+support they will quickly work loose, both in the
+bearing seat and bearing cap.</p>
+
+<h3><a name="SecXI_28" id="SecXI_28"></a>SCRAPING BRASSES TO FIT</h3>
+
+<p>To insure that the bearing brasses will be a good fit
+on the trued-up crank-pins or crank-shaft journals, they
+must be scraped to fit the various crank-shaft journals.
+The process of scraping, while a tedious one, is not difficult,
+requiring only patience and some degree of care to
+do a good job. The surface of the crank-pin is smeared
+with Prussian blue pigment which is spread evenly over
+the entire surface. The bearings are then clamped together
+in the usual manner with the proper bolts, and the
+crank-shaft revolved several times to indicate the high
+spots on the bearing cap. At the start of the process of
+scraping in, the bearing may seat only at a few points as
+shown at <a href="#Fig187">Fig. 187</a>, G. Continued scraping will bring the
+bearing surface as indicated at H, which is a considerable
+improvement, while the process may be considered
+complete when the brass indicates a bearing all over as
+at I. The high spots are indicated by blue, as where the
+shaft does not bear on the bearing there is no color.
+The high spots are removed by means of a scraping tool
+of the form shown at <a href="#Fig187">Fig. 187</a>, F, which is easily made
+from a worn-out file. These are forged to shape and
+ground hollow as indicated in the section, and are kept
+properly sharpened by frequent rubbing on an ordinary
+oil stone. To scrape properly, the edge of the scraper
+must be very keen. The straight and curved half-round
+scrapers, shown at M and N, are used for bearings. The<span class='pagenum'><a name="Page_447" id="Page_447">[447]</a></span>
+three-cornered scraper, outlined at O, is also used on
+curved surfaces, and is of value in rounding off the sharp
+corners. The straight or curved half-round type works
+well on soft-bearing metals, such as babbitt, or white brass,
+but on yellow brass or bronze it cuts very slowly, and as
+soon as the edge becomes dull considerable pressure is
+needed to remove any metal, this calling for frequent
+sharpening.</p>
+
+<p>When correcting errors on flat or curved surfaces by
+hand-scraping, it is desirable, of course, to obtain an
+evenly spotted bearing with as little scraping as possible.
+When the part to be scraped is first applied to the surface-plate,
+or to a journal in the case of a bearing, three
+or four &#8220;high&#8221; spots may be indicated by the marking
+material. The time required to reduce these high spots
+and obtain a bearing that is distributed over the entire
+surface depends largely upon the way the scraping is
+started. If the first bearing marks indicate a decided
+rise in the surface, much time can be saved by scraping
+larger areas than are covered by the bearing marks; this
+is especially true of large shaft and engine bearings, etc.
+An experienced workman will not only remove the heavy
+marks, but also reduce a larger area; then, when the
+bearing is tested again, the marks will generally be distributed
+somewhat. If the heavy marks which usually
+appear at first are simply removed by light scraping,
+these &#8220;point bearings&#8221; are gradually enlarged, but a
+much longer time will be required to distribute them.</p>
+
+<p>The number of times the bearing must be applied to
+the journal for testing is important, especially when the
+box or bearing is large and not easily handled. The time
+required to distribute the bearing marks evenly depends
+largely upon one&#8217;s judgment in &#8220;reading&#8221; these marks.
+In the early stages of the scraping operation, the marks
+should be used partly as a guide for showing the high
+areas, and instead of merely scraping the marked spot
+the surface surrounding it should also be reduced, unless
+it is evident that the unevenness is local. The idea should<span class='pagenum'><a name="Page_448" id="Page_448">[448]</a></span>
+be to obtain first a few large but generally distributed
+marks; then an evenly and finely spotted surface can be
+produced quite easily.</p>
+
+<p>In fitting brasses when these are of the removable
+type, two methods may be used. The upper half of the
+engine base may be inverted on a suitable bench or stand
+and the boxes fitted by placing the crank-shaft in position,
+clamping down one bearing cap at a time and fitting each
+bearing in succession until they bed equally. From that
+time on the bearings should be fitted at the same time
+so the shaft will be parallel with the bottom of the cylinders.
+Considerable time and handling of the heavy crank-shaft
+may be saved if a preliminary fitting of the bearing
+brasses is made by clamping them together with a carpenter&#8217;s
+wood clamp as shown at <a href="#Fig187">Fig. 187</a>, J, and leaving
+the crank-shaft attached to the bench as shown at C.
+The brasses are revolved around the crank-shaft journal
+and are scraped to fit wherever high spots are indicated
+until they begin to seat fairly. When the brasses assume
+a finished appearance the final scraping should be carried
+on with all bearings in place and revolving the crank-shaft
+to determine the area of the seating. When the
+brasses are properly fitted they will not only show a full
+bearing surface, but the shaft will not turn unduly hard
+if revolved with a moderate amount of leverage.</p>
+
+<p>Bearings of white metal or babbitt can be fitted tighter
+than those of bronze, and care must be observed in supplying
+lubricant as considerably more than the usual
+amount is needed until the bearings are run in by several
+hours of test block work. Before the scraping process
+is started it is well to chisel an oil groove in the bearing
+as shown at <a href="#Fig187">Fig. 187</a>, L. Grooves are very helpful in
+insuring uniform distribution of oil over the entire width
+of bearing and at the same time act as reservoirs to retain
+a supply of oil. The tool used is a round-nosed chisel,
+the effort being made to cut the grooves of uniform
+depth and having smooth sides. Care should be taken
+not to cut the grooves too deeply, as this will seriously<span class='pagenum'><a name="Page_449" id="Page_449">[449]</a></span>
+reduce the strength of the bearing bushing. The shape
+of the groove ordinarily provided is clearly shown at
+<a href="#Fig187">Fig. 187</a>, G, and it will be observed that the grooves do
+not extend clear to the edge of the bearing, but stop about
+a quarter of an inch from that point. The hole through
+which the oil is supplied to the bearing is usually drilled
+in such a way that it will communicate with the groove.</p>
+
+<p>The tool shown at <a href="#Fig187">Fig. 187</a>, K, is of recent development,
+and is known as a &#8220;crank-shaft equalizer.&#8221; This
+is a hand-operated turning tool, carrying cutters which are
+intended to smooth down scored crank-pins without using
+a lathe. The feed may be adjusted by suitable screws
+and the device may be fitted to crank-pins and shaft-journals
+of different diameters by other adjusting screws.
+This device is not hard to operate, being merely clamped
+around the crank-shaft in the same manner as the lapping
+tool previously described, and after it has been properly
+adjusted it is turned around by the levers provided for
+the purpose, the continuous rotary motion removing the
+metal just as a lathe tool would.</p>
+
+<h3><a name="SecXI_29" id="SecXI_29"></a>FITTING CONNECTING RODS</h3>
+
+<p>In the marine type rod, which is the form generally
+used in airplane engines, one or two bolts are employed
+at each side and the cap must be removed entirely before
+the bearing can be taken off of the crank-pin. The tightness
+of the brasses around the crank-pin can never be
+determined solely by the adjustment of the bolts, as while
+it is important that these should be drawn up as tightly
+as possible, the bearing should fit the shaft without undue
+binding, even if the brasses must be scraped to insure
+a proper fit. As is true of the main bearings, the marine
+form of connecting rod in some engines has a number of
+liners or shims interposed between the top and lower
+portions of the rod end, and these may be reduced in
+number when necessary to bring the brasses closer together.
+The general tendency in airplane engines is to<span class='pagenum'><a name="Page_450" id="Page_450">[450]</a></span>
+eliminate shims in either the main or connecting rod
+bearings, and when wear is noticed the boxes or liners are
+removed and new ones supplied. The brasses are held
+in the connecting rod and cap by brass rivets and are
+generally attached in the main bearing by small brass
+machine screws. The form of box generally favored is
+a brass sand casting rich in copper to secure good heat
+conductivity which forms a backing for a thin layer of
+white brass, babbitt or similar anti-friction metal.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig188" id="Fig188"></a>
+<img src="images/illo445.png" alt="Fig. 188" width="600" height="320" />
+<p class="caption">Fig. 188.&mdash;Showing Points to Observe When Fitting Connecting Rod
+Brasses.</p></div>
+
+<p>In fitting new brasses there are two conditions to be
+avoided, these being outlined at <a href="#Fig188">Fig. 188</a>, B and C. In
+the case shown at C the light edges of the bushings are
+in contact, but the connecting rod and its cap do not meet.
+When the retaining nuts are tightened the entire strain
+is taken on the comparatively small area of the edges of
+the bushings which are not strong enough to withstand
+the strains existing and which flatten out quickly, permitting
+the bearing to run loose. In the example outlined
+at B the edges of the brasses do not touch when
+the connecting rod cap is drawn in place. This is not
+good practice, because the brasses soon become loose in
+their retaining member. In the case outlined it is necessary<span class='pagenum'><a name="Page_451" id="Page_451">[451]</a></span>
+to file off the faces of the rod and cap until these
+meet, and to insure contact of the edges of the brasses
+as well. In event of the brasses coming together before
+the cap and rod make contact, as shown at C, the bearing
+halves should be reduced at the edges until both the caps
+and brasses meet against each other or the surfaces of
+the liners as shown at A.</p>
+
+<h3>SPRUNG CAM-SHAFT</h3>
+
+<p>If the cam-shaft is sprung or twisted it will alter the
+valve timing to such an extent that the smoothness of
+operation of the engine will be materially affected. If
+this condition is suspected the cam-shaft may be swung
+on lathe centers and turned to see if it runs out and can
+be straightened in any of the usual form of shaft-straightening
+machines. The shaft may be twisted without being
+sprung. This can only be determined by supporting one
+end of the shaft in an index head and the other end on
+a milling machine center. The cams are then checked to
+see that they are separated by the proper degree of angularity.
+This process is one that requires a thorough
+knowledge of the valve timing of the engine in question,
+and is best done at the factory where the engine was
+made. The timing gears should also be examined to see
+if the teeth are worn enough so that considerable back
+lash or lost motion exists between them. This is especially
+important where worm or spiral gears are used.
+A worn timing gear not only produces noise, but it will
+cause the time of opening and closing of the engine valves
+to vary materially.</p>
+
+<h3><a name="SecXI_32" id="SecXI_32"></a>PRECAUTIONS IN REASSEMBLING PARTS</h3>
+
+<p>When all of the essential components of a power plant
+have been carefully looked over and cleaned and all defects
+eliminated, either by adjustment or replacement of
+worn portions, the motor should be reassembled, taking<span class='pagenum'><a name="Page_452" id="Page_452">[452]</a></span>
+care to have the parts occupy just the same relative positions
+they did before the motor was dismantled. As each
+part is added to the assemblage care should be taken to
+insure adequate lubrication of all new points of bearing
+by squirting liberal quantities of cylinder oil upon them
+with a hand oil can or syringe provided for the purpose.
+In adjusting the crank-shaft bearings, tighten them one
+at a time and revolve the shafts each time one of the
+bearing caps is set up to insure that the newly adjusted
+bearing does not have undue friction. All retaining keys
+and pins must be positively placed and it is good practice
+to cover such a part with lubricant before replacing it
+because it will not only drive in easier, but the part may
+be removed more easily if necessary at some future time.
+If not oiled, rust collects around it.</p>
+
+<p>When a piece is held by more than one bolt or screw,
+especially if it is a casting of brittle material such as
+cast iron or aluminum, the fastening bolts should be tightened
+uniformly. If one bolt is tightened more than the
+rest it is liable to spring the casting enough to break it.
+Spring washers, check nuts, split pins or other locking
+means should always be provided, especially on parts
+which are in motion or subjected to heavy loads.</p>
+
+<p>Before placing the cylinder over the piston it is imperative
+that the slots in the piston rings are spaced
+equidistant and that the piston is copiously oiled before
+the cylinder is slipped over it. When reassembling the
+inlet and exhaust manifolds it is well to use only perfect
+packings or gaskets and to avoid the use of those that
+seem to have hardened up or flattened out too much in
+service. If it is necessary to use new gaskets it is imperative
+to employ these at all joints on a manifold, because
+if old and new gaskets are used together the new
+ones are apt to keep the manifold from bedding properly
+upon the used ones. It is well to coat the threads of all
+bolts and screws subjected to heat, such as cylinder head
+and exhaust manifold retaining bolts, with a mixture of
+graphite and oil. Those that enter the water jacket should<span class='pagenum'><a name="Page_453" id="Page_453">[453]</a></span>
+be covered with white or red lead or pipe thread compound.
+Gaskets will hold better if coated with shellac
+before the manifold or other parts are placed over them.
+The shellac fills any irregularities in the joint and assists
+materially in preventing leakage after the joint is made
+up and the coating has a chance to set.</p>
+
+<p>Before assembling on the shaft, it is necessary to fit
+the bearings by scraping, the same instructions given for
+restoring the contour of the main bearings applying just
+as well in this case. It is apparent that if the crank-pins
+are not round no amount of scraping will insure a true
+bearing. A point to observe is to make sure that the
+heads of the bolts are imbedded solidly in their proper
+position, and that they are not raised by any burrs or
+particles of dirt under the head which will flatten out
+after the engine has been run for a time and allow the
+bolts to slack off. Similarly, care should be taken that
+there is no foreign matter under the brasses and the
+box in which they seat. To guard against this the bolts
+should be struck with a hammer several times after they
+are tightened up, and the connecting rod can be hit
+sharply several times under the cap with a wooden mallet
+or lead hammer. It is important to pin the brasses in
+place to prevent movement, as lubrication may be interfered
+with if the bushing turns round and breaks the correct
+register between the oil hole in the cap and brasses.</p>
+
+<p>Care should be taken in screwing on the retaining nuts
+to insure that they will remain in place and not slack off.
+Spring washers should not be used on either connecting
+rod ends or main bearing nuts, because these sometimes
+snap in two pieces and leave the nut slack. The best
+method of locking is to use well-fitting split pins and
+castellated nuts.</p>
+
+<h3><a name="SecXI_30" id="SecXI_30"></a>TESTING BEARING PARALLELISM</h3>
+
+<p>It is not possible to give other than general directions
+regarding the proper degree of tightening for a connecting
+rod bearing, but as a guide to correct adjustment<span class='pagenum'><a name="Page_454" id="Page_454">[454]</a></span>
+it may be said that if the connecting rod cap is tightened
+sufficiently so the connecting rod will just about fall over
+from a vertical position due to the piston weight when
+the bolts are fully tightened up, the adjustment will be
+nearly correct. As previously stated, babbitt or white
+metal bearings can be set up more tightly than bronze,
+as the metal is softer and any high spots will soon be
+leveled down with the running of the engine. It is important
+that care be taken to preserve parallelism of
+the wrist-pins and crank-shafts while scraping in bearings.
+This can be determined in two ways. That shown
+at <a href="#Fig189">Fig. 189</a>, A, is used when the parts are not in the
+engine assembly and when the connecting rod bearing is
+being fitted to a mandrel or arbor the same size as the
+crank-pin. The arbor, which is finished very smooth and
+of uniform diameter, is placed in two V blocks, which in
+turn are supported by a level surface plate. An adjustable
+height gauge may be tried, first at one side of
+the wrist-pin which is placed at the upper end of the
+connecting rod, then at the other, and any variation will
+be easily determined by the degree of tilting of the rod.
+This test may be made with the wrist-pin alone, or if
+the piston is in place, a straight edge or spirit level may
+be employed. The spirit level will readily show any inclination
+while the straight edge is used in connection
+with the height gauge as indicated. Of course, the surface
+plate must be absolutely level when tests are made.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig189" id="Fig189"></a>
+<img src="images/illo450.png" alt="Fig. 189" width="400" height="450" />
+<p class="caption">Fig. 189.&mdash;Methods of Testing to Insure Parallelism of Bearings After
+Fitting.</p></div>
+
+<p>When the connecting rods are being fitted with the
+crank-shaft in place in crank-case, and that member secured
+in the frame, a steel square may be used as it is
+reasonable to assume that the wrist-pin, and consequently
+the piston it carries, should observe a true relation with
+the top of the engine base. If the piston side is at right
+angles with the top of the engine base it is reasonable
+to assume that the wrist-pin and crank-pin are parallel.
+If the piston is canted to one side or the other, it will
+indicate that the brasses have been scraped tapering,
+which would mean considerable heating and undue friction<span class='pagenum'><a name="Page_455" id="Page_455">[455]</a></span>
+if the piston is installed in the cylinder on account
+of the pressure against one portion of the cylinder wall.
+If the degree of canting is not too great, the connecting
+rods may be sprung very slightly to straighten up the
+piston, but this is a makeshift that is not advised. The
+height gauge method shown above may be used instead
+of the steel square, if desired, because the top of the
+crank-case is planed or milled true and should be parallel
+with the center line of the crank-shaft.</p>
+
+<p class='pagenum'><a name="Page_456" id="Page_456">[456]</a></p>
+
+<h3><a name="SecXI_31" id="SecXI_31"></a>CAM-SHAFTS AND TIMING GEARS</h3>
+
+<p>Knocking sounds are also evident if the cam-shaft is
+loose in its bearings, and also if the cams or timing
+gears are loose on the shaft. The cam-shaft is usually
+supported by solid bearings of the removable bushing
+type, having no compensation for depreciation. If these
+bearings wear the only remedy is replacement with new
+ones. In the older makes of cars it was general practice
+to machine the cams separately and to secure these to the
+cam-shaft by means of taper pins or keys. These members
+sometimes loosened and caused noise. In the event
+of the cams being loose, care should be taken to use new
+keys or taper pins, as the case may be. If the fastening
+used was a pin, the hole through the cam-shaft will
+invariably be slightly oval from wear. In order to insure
+a tight job, the holes in cam and shaft must be reamed
+with the next larger size of standard taper reamer and
+a larger pin driven in. Another point to watch is the
+method of retaining the cam-shaft gear in place. On
+some engines the gear is fastened to a flange on the
+cam-shaft by retaining screws. These are not apt to
+become loose, but where reliance is placed on a key the
+cam-shaft gear may often be loose on its supporting
+member. The only remedy is to enlarge the key slot
+in both gear and shaft and to fit a larger retaining key.</p>
+
+<hr class="c25" />
+<p class='pagenum'><a name="Page_457" id="Page_457">[457]</a></p>
+
+<h2><a name="ChXII" id="ChXII"></a>CHAPTER XII</h2>
+
+<div class="chapsec"><p><a href="#SecXII_1">Aviation Engine Types</a>&mdash;<a href="#SecXII_2">Division in Classes</a>&mdash;<a
+href="#SecXII_3">Anzani Engines</a>&mdash;<a href="#SecXII_4">Canton and Unn&eacute; Engine</a>&mdash;<a href="#SecXII_5">Construction of
+Gnome Engines</a>&mdash;<a href="#SecXII_6">&#8220;Monosoupape&#8221; Gnome</a>&mdash;<a href="#SecXII_7">German &#8220;Gnome&#8221;
+Type</a>&mdash;<a href="#SecXII_8">Le Rhone Engine</a>&mdash;<a href="#SecXII_9">Renault Air-Cooled Engine</a>&mdash;<a
+href="#SecXII_10">Simplex Model &#8220;A&#8221; Hispano-Suiza</a>&mdash;<a href="#SecXII_11">Curtiss Aviation Motors</a>&mdash;<a
+href="#SecXII_12">Thomas-Morse Model 88 Engine</a>&mdash;<a href="#SecXII_13">Duesenberg Engine</a>&mdash;<a href="#SecXII_14">Aeromarine
+Six-Cylinder</a>&mdash;<a href="#SecXII_15">Wisconsin Aviation Engines</a>&mdash;<a href="#SecXII_16">Hall-Scott Engines</a>&mdash;<a
+href="#SecXII_17">Mercedes Motor</a>&mdash;<a href="#SecXII_18">Benz Motor</a>&mdash;<a href="#SecXII_19">Austro-Daimler</a>&mdash;<a
+href="#SecXII_20">Sunbeam-Coatalen</a>.</p></div>
+
+<h3><a name="SecXII_1" id="SecXII_1"></a>AVIATION ENGINE TYPES</h3>
+
+<p>Inasmuch as numerous forms of airplane engines have
+been devised, it would require a volume of considerable
+size to describe even the most important developments
+of recent years. As considerable explanatory matter has
+been given in preceding chapters and the principles involved
+in internal combustion engine operation considered
+in detail, a relatively brief review of the features
+of some of the most successful airplane motors should
+suffice to give the reader a complete enough understanding
+of the art so all types of engines can be readily
+recognized and the advantages and disadvantages of each
+type understood, as well as defining the constructional
+features enough so the methods of locating and repairing
+the common engine and auxiliary system troubles
+will be fully grasped.</p>
+
+<p><a name="SecXII_2" id="SecXII_2"></a>Aviation engines can be divided into three main
+classes. One of the earliest attempts to devise distinctive
+power plant designs for aircraft involved the construction
+of engines utilizing a radial arrangement of the
+cylinders or a star-wise disposition. Among the engines
+of this class may be mentioned the Anzani, R. E. P. and
+the Salmson or Canton and Unn&eacute; forms. The two former
+are air-cooled, the latter design is water-cooled. Engines<span class='pagenum'><a name="Page_458" id="Page_458">[458]</a></span>
+of this type have been built in cylinder numbers ranging
+from three to twenty. While the simple forms were
+popular in the early days of aviation engine development,
+they have been succeeded by the more conventional
+arrangements which now form the largest class. The
+reason for the adoption of a star-wise arrangement of
+cylinders has been previously considered. Smoothness
+of running can only be obtained by using a considerable
+number of cylinders. The fundamental reason for the
+adoption of the star-wise disposition is that a better distribution
+of stress is obtained by having all of the pistons
+acting on the same crank-pin so that the crank-throw and
+pin are continuously under maximum stress. Some difficulty
+has been experienced in lubricating the lower cylinders
+in some forms of six cylinder, rotary crank, radial
+engines but these have been largely overcome so they are
+not as serious in practice as a theoretical consideration
+would indicate.</p>
+
+<p>Another class of engines developed to meet aviation
+requirements is a complete departure from the preceding
+class, though when the engines are at rest, it is difficult
+to differentiate between them. This class includes engines
+having a star-wise disposition of the cylinders but
+the cylinders themselves and the crank-case rotate and
+the crank-shaft remains stationary. The important rotary
+engines are the Gnome, the Le Rhone and the Clerget.
+By far the most important classification is that including
+engines which retain the approved design of the
+types of power plants that have been so widely utilized
+in automobiles and which have but slight modifications
+to increase reliability and mechanical strength and produce
+a reduction in weight. This class includes the
+vertical engines such as the Duesenberg and Hall-Scott
+four-cylinder; the Wisconsin, Aeromarine, Mercedes,
+Benz, and Hall-Scott six-cylinder vertical engines and
+the numerous eight- and twelve-cylinder Vee designs such
+as the Curtiss, Renault, Thomas-Morse, Sturtevant, Sunbeam,
+and others.</p>
+
+<p class='pagenum'><a name="Page_459" id="Page_459">[459]</a></p>
+
+<h3><a name="SecXII_3" id="SecXII_3"></a>ANZANI ENGINES</h3>
+
+<p>The attention of the mechanical world was first directed
+to the great possibilities of mechanical flight when
+Bleriot crossed the English Channel in July, 1909, in a
+monoplane of his own design and construction, having
+the power furnished by a small three-cylinder air-cooled
+engine rated at about 24 horse-power and having cylinders
+4.13 inches bore and 5.12 inches stroke, stated to
+develop the power at about 1600 R.P.M. and weighing 145
+pounds. The arrangement of this early Anzani engine is
+shown at <a href="#Fig190">Fig. 190</a>, and it will be apparent that in the
+main, the lines worked out in motorcycle practice were
+followed to a large extent. The crank-case was of the
+usual vertically divided pattern, the cylinders and heads
+being cast in one piece and held to the crank-case by
+stud bolts passing through substantial flanges at the
+cylinder base. In order to utilize but a single crank-pin
+for the three cylinders it was necessary to use two forked
+rods and one rod of the conventional type. The arrangement
+shown at <a href="#Fig190">Fig. 190</a>, called for the use of counter-balanced
+flywheels which were built up in connection
+with shafts and a crank-pin to form what corresponds to
+the usual crank-shaft assembly.</p>
+
+<p class='pagenum' style="margin-top: -1.5em;"><a name="Page_460" id="Page_460">[460]</a></p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig190" id="Fig190"></a>
+<p class="leftlink"><a href="images/large455.png">Large<br />image<br />(90 kB).</a></p>
+<img src="images/illo455.png" alt="Fig. 190" width="600" height="348" />
+<p class="caption">Fig. 190.&mdash;Views Outlining Construction of Three-Cylinder Anzani Aviation Motor.</p></div>
+
+<p class='pagenum'><a name="Page_461" id="Page_461">[461]</a></p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig190a" id="Fig190a"></a>
+<img src="images/illo456.png" alt="Fig. 190a" width="350" height="586" />
+<p class="caption">Fig. 190a.&mdash;Illustrations Depicting Wrong and Right Methods of &#8220;Swinging
+the Stick&#8221; to Start Airplane Engine. At Top, Poor Position to
+Get Full Throw and Get Out of the Way. Below, Correct Position
+to Get Quick Turn Over of Crank-Shaft and Spring Away from
+Propeller.</p></div>
+
+<p>The inlet valves were of the automatic type so that a
+very simple valve mechanism consisting only of the exhaust
+valve push rods was provided. One of the difficulties
+of this arrangement of cylinders was that the
+impulses are not evenly spaced. For instance, in the
+forms where the cylinders were placed 60 degrees apart
+the space between the firing of the first cylinder and that
+next in order was 120 degrees crank-shaft rotation, after
+which there was an interval of 300 degrees before the
+last cylinder to fire delivered its power stroke. In order
+to increase the power given by the simple three-cylinder
+air-cooled engine a six-cylinder water-cooled type, as
+shown at <a href="#Fig191">Figs. 191</a> and <a href="#Fig192">192</a>, was devised. This was practically
+the same in action as the three-cylinder except<span class='pagenum'><a name="Page_462" id="Page_462">[462]</a></span>
+that a double throw crank-shaft was used and while the
+explosions were not evenly spaced the number of explosions
+obtained resulted in fairly uniform application of
+power.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig191" id="Fig191"></a>
+<img src="images/illo457.jpg" alt="Fig. 191" width="450" height="355" />
+<p class="caption">Fig. 191.&mdash;The Anzani Six-Cylinder Water-Cooled Aviation Engine.</p></div>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig192" id="Fig192"></a>
+<img src="images/illo458.png" alt="Fig. 192" width="450" height="383" />
+<p class="caption">Fig. 192.&mdash;Sectional View of Anzani Six-Cylinder Water-Cooled Aviation
+Engine.</p></div>
+
+<p>The latest design of three-cylinder Anzani engine,
+which is used to some extent for school machines, is
+shown at <a href="#Fig193">Fig. 193</a>. In this, the three-cylinders are symmetrically
+arranged about the crank-case or 120 degrees
+apart. The balance is greatly improved by this arrangement
+and the power strokes occur at equal intervals of
+240 degrees of crank-shaft rotation. This method of construction
+is known as the Y design. By grouping two of
+these engines together, as outlined at <a href="#Fig194">Fig. 194</a>, which
+gives an internal view, and at <a href="#Fig195">Fig. 195</a>, which shows the
+sectional view, and using the ordinary form of double
+throw crank-shaft with crank-pins separated by 180 degrees,
+a six-cylinder radial engine is produced which runs<span class='pagenum'><a name="Page_463" id="Page_463">[463]</a></span>
+very quietly and furnishes a steady output of power.
+The peculiarity of the construction of this engine is in
+the method of grouping the connecting rod about the
+common crank-pin without using forked rods or the
+&#8220;Mother rod&#8221; system employed in the Gnome engines.
+In the Anzani the method followed is to provide each
+connecting rod big end with a shoe which consists of a
+portion of a hollow cylinder held against the crank-pin
+by split clamping rings. The dimensions of these shoes
+are so proportioned that the two adjacent connecting rods
+of a group of three will not come into contact even when
+the connecting rods are at the minimum relative angle.
+The three shoes of each group rest upon a bronze sleeve
+which is in halves and which surrounds the crank-pin<span class='pagenum'><a name="Page_464" id="Page_464">[464]</a></span>
+and rotates relatively to it once in each crank-shaft revolution.
+The collars, which are of tough bronze, resist the
+inertia forces while the direct pressure of the explosions
+is transmitted directly to the crank-pin bushing by the
+shoes at the big end of the connecting rod. The same
+method of construction, modified to some extent, is used
+in the Le Rhone rotary cylinder engine.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig193" id="Fig193"></a>
+<img src="images/illo459.png" alt="Fig. 193" width="450" height="477" />
+<p class="caption">Fig. 193.&mdash;Three-Cylinder Anzani Air-Cooled Y-Form Engine.</p></div>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig194" id="Fig194"></a>
+<img src="images/illo460.png" alt="Fig. 194" width="450" height="460" />
+<p class="caption">Fig. 194.&mdash;Anzani Fixed Crank-Case Engine of the Six-Cylinder Form
+Utilizes Air Cooling Successfully.</p></div>
+
+<p>Both cylinders and pistons of the Anzani engines are
+of cast iron, the cylinders being provided with a liberal
+number of cooling flanges which are cast integrally. A
+series of auxiliary exhaust ports is drilled near the base<span class='pagenum'><a name="Page_465" id="Page_465">[465]</a></span>
+of each cylinder so that a portion of the exhaust gases
+will flow out of the cylinder when the piston reaches the
+end of its power stroke. This reduces the temperature
+of the gases passing around the exhaust valves and prevents
+warping of these members. Another distinctive
+feature of this engine design is the method of attaching
+the Zenith carburetor to an annular chamber surrounding
+the rear portion of the crank-case from which the intake
+pipes leading to the intake valves radiate. The magneto<span class='pagenum'><a name="Page_466" id="Page_466">[466]</a></span>
+is the usual six-cylinder form having the armature geared
+to revolve at one and one-half times crank-shaft speed.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig195" id="Fig195"></a>
+<img src="images/illo461.png" alt="Fig. 195" width="400" height="565" />
+<p class="caption">Fig. 195.&mdash;Sectional View Showing Internal Parts of Six-Cylinder Anzani
+Engine, with Starwise Disposition of Cylinders.</p></div>
+
+<p class='pagenum' style="margin-top: -1.5em;"><a name="Page_467" id="Page_467">[467]</a></p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig196" id="Fig196"></a>
+<img src="images/illo462.png" alt="Fig. 196" width="600" height="342" />
+<p class="caption">Fig. 196.&mdash;The Anzani Ten-Cylinder Aviation Engine at the Left, and the Twenty-Cylinder Fixed Type
+at the Right.</p></div>
+
+<p>The Anzani aviation engines are also made in ten- and
+twenty-cylinder forms as shown at <a href="#Fig196">Fig. 196</a>. It
+will<span class='pagenum'><a name="Page_468" id="Page_468">[468]</a></span>
+be apparent that in the ten-cylinder form explosions will
+occur every 72 degrees of crank-shaft rotation, while in
+the twenty-cylinder, 200 horse-power engine at any instant
+five of the cylinders are always working and explosions
+are occurring every 36 degrees of crank-shaft
+rotation. On the twenty-cylinder engine, two carburetors<span class='pagenum'><a name="Page_469" id="Page_469">[469]</a></span>
+are used and two magnetos, which are driven at two and
+one-half times crank-shaft speed. The general cylinder
+and valve construction is practically the same, as in the
+simpler engines.</p>
+
+<h3><a name="SecXII_4" id="SecXII_4"></a>CANTON AND UNN&Eacute; ENGINE</h3>
+
+<p>This engine, which has been devised specially for
+aviation service, is generally known as the &#8220;Salmson&#8221;
+and is manufactured in both France and Great Britain.
+It is a nine-cylinder water-cooled radial engine, the nine
+cylinders being symmetrically disposed around the crank-shaft
+while the nine connecting rods all operate on a
+common crank-pin in somewhat the same manner as the
+rods in the Gnome motor. The crank-shaft of the Salmson
+engine is not a fixed one and inasmuch as the cylinders
+do not rotate about the crank-shaft it is necessary
+for that member to revolve as in the conventional engine.
+The stout hollow steel crank-shaft is in two pieces and
+has a single throw. The crank-shaft is built up somewhat
+the same as that of the Gnome engine. Ball bearings
+are used throughout this engine as will be evident
+by inspecting the sectional view given at <a href="#Fig199">Fig. 199</a>. The
+nine steel connecting rods are machined all over and are
+fitted at each end with bronze bushings, the distance
+between the bearing centers being about 3.25 times crank
+length. The method of connecting up the rods to the
+crank-pin is one of the characteristic features of this
+design. No &#8220;mother&#8221; rod as supplied in the Gnome
+engine is used in this type inasmuch as the steel cage or
+connecting rod carrier is fitted with symmetrically disposed
+big end retaining pins. Inasmuch as the carrier
+is mounted on ball bearings some means must be provided
+of regulating the motion of the carrier as if no
+means were provided the resulting motion of the pistons
+would be irregular.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig197" id="Fig197"></a>
+<img src="images/illo463.jpg" alt="Fig. 197" width="400" height="498" />
+<p class="caption">Fig. 197.&mdash;Application of R. E. P. Five-Cylinder Fan-Shape Air-Cooled
+Motor to Early Monoplane.</p></div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig198" id="Fig198"></a>
+<img src="images/illo465.jpg" alt="Fig. 198" width="400" height="467" />
+<p class="caption">Fig. 198.&mdash;The Canton and Unn&eacute; Nine-Cylinder Water-Cooled Radial
+Engine.</p></div>
+
+<p>The method by which the piston strokes are made to
+occur at precise intervals involves a somewhat lengthy
+and detailed technical explanation. It is sufficient to say<span class='pagenum'><a name="Page_470" id="Page_470">[470]</a></span>
+that an epicyclic train of gears, one of which is rigidly
+attached to the crank-case so it cannot rotate is used,
+while other gears make a connection between the fixed
+gear and with another gear which is exactly the same
+size as the fixed gear attached to the crank-case and which
+is formed integrally with the connecting rod carrier. The
+action of the gearing is such that the cage carrying the
+big end retaining pins does not rotate independently of<span class='pagenum'><a name="Page_471" id="Page_471">[471]</a></span>
+the crank-shaft, though, of course, the crank-shaft or
+rather crank-pin bearings must turn inside of the big
+end carrier cage.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig199" id="Fig199"></a>
+<img src="images/illo466.png" alt="Fig. 199" width="500" height="500" />
+<p class="caption">Fig. 199.&mdash;Sectional View Showing Construction of Canton and Unn&eacute;
+Water-Cooled Radial Cylinder Engine.</p></div>
+
+<p>Cylinders of this engine are of nickel steel machined
+all over and carry water-jackets of spun copper which
+are attached to the cylinders by brazing. The water
+jackets are corrugated to permit the cylinder to expand
+freely. The ignition is similar to that of the fixed crank
+rotating cylinder engine. An ordinary magneto of the
+two spark type driven at 1<sup>3</sup>&#8260;<sub>4</sub> times crank-shaft speed is
+sufficient to ignite the seven-cylinder form, while in the<span class='pagenum'><a name="Page_472" id="Page_472">[472]</a></span>
+nine-cylinder engines the ignition magneto is of the
+&#8220;shield&#8221; type giving four sparks per revolution. The
+magneto is driven at 1<sup>1</sup>&#8260;<sub>9</sub> times crank-shaft speed. Nickel
+steel valves are used and are carried in castings or cages
+which screw into bosses in the cylinder head. Each
+valve is cam operated through a tappet, push rod and
+rocker arm, seven cams being used on a seven-cylinder
+engine and nine cams on the nine-cylinder. One cam
+serves to open both valves as in its rotation it lifts the
+tappets in succession and so operates the exhaust and
+inlet valves respectively. This method of operation involves
+the same period of intake and exhaust. In normal
+engine practice the inlet valve opens 12 degrees
+late and closes 20 degrees late. The exhaust opens
+45 degrees early and closes 6 degrees late. This means
+about 188 degrees in the case of inlet valve and 231 degrees
+crank-shaft travel for exhaust valves. In the
+Salmson engine, the exhaust closes and the inlet opens at
+the outer dead center and the exhaust opens and the inlet
+closes at about the inner dead center. This engine is
+also made in a fourteen-cylinder 200 B.&nbsp;H.&nbsp;P. design
+which is composed of two groups of seven-cylinders, and
+it has been made in an eighteen-cylinder design of 600
+horse-power. The nine-cylinder 130 horse-power has a
+cylinder bore of 4.73 inches and a stroke of 5.52 inches.
+Its normal speed of rotation is 1250 R.&nbsp;P.&nbsp;M. Owing to
+the radial arrangement of the cylinders, the weight is but
+4<sup>1</sup>&#8260;<sub>4</sub> pounds per B.&nbsp;H.&nbsp;P.</p>
+
+<h3><a name="SecXII_5" id="SecXII_5"></a>CONSTRUCTION OF EARLY GNOME MOTOR</h3>
+
+<p>It cannot be denied that for a time one of the most
+widely used of aeroplane motors was the seven-cylinder
+revolving air-cooled Gnome, made in France. For a total
+weight of 167 pounds this motor developed 45 to 47 horsepower
+at 1,000 revolutions, being equal to 3.35 pounds
+per horse-power, and has proved its reliability by securing
+many long-distance and endurance records. The same<span class='pagenum'><a
+name="Page_474" id="Page_474">[474]</a></span><span class='pagenum'><a name="Page_473" id="Page_473"></a></span>
+engineers have produced a nine-cylinder and by combining
+two single engines a fourteen-cylinder revolving
+Gnome, having a nominal rating of 100 horse-power, with
+which world&#8217;s speed records were broken. A still more
+powerful engine has been made with eighteen-cylinders.
+The nine-cylinder &#8220;monosoupape&#8221; delivers 100 horse-power
+at 1200 R.&nbsp;P.&nbsp;M., the engine of double that number
+of cylinders is rated at about 180 horse-power.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig200" id="Fig200"></a>
+<p class="leftlink"><a href="images/large468.png">Large<br />image<br />(89 kB).</a></p>
+<img src="images/illo468.png" alt="Fig. 200" width="600" height="370" />
+<p class="caption">Fig. 200.&mdash;Sectional View Outlining Construction of Early Type Gnome Valve-in-Piston Type Motor.</p></div>
+
+<p>Except in the number of cylinders and a few mechanical
+details the fourteen-cylinder motor is identical with
+the seven-cylinder one; fully three-quarters of the parts
+used by the assemblers would do just as well for one
+motor as for the other. Owing to the greater power demands
+of the modern airplane the smaller sizes of Gnome
+engines are not used as much as they were except for
+school machines. There is very little in this motor that
+is common to the standard type of vertical motorcar
+engine. The cylinders are mounted radially round a circular
+crank-case; the crank-shaft is fixed, and the entire
+mass of cylinders and crank-case revolves around it as
+outlined at <a href="#Fig200">Fig. 200</a>. The explosive mixture and the
+lubricating oil are admitted through the fixed hollow
+crank-shaft, passed into the explosion chamber through
+an automatic intake valve in the piston head in the early
+pattern, and the spent gases exhausted through a mechanically
+operated valve in the cylinder head. The
+course of the gases is practically a radial one. A peculiarity
+of the construction of the motor is that nickel steel
+is used throughout. Aluminum is employed for the two
+oil pump housings; the single compression ring known
+as the &#8220;obdurator&#8221; for each piston is made of brass;
+there are three or four brass bushes; gun metal is employed
+for certain pins&mdash;the rest is machined out of
+chrome nickel steel. The crank-case is practically a steel
+hoop, the depth depending on whether it has to receive
+seven-or fourteen-cylinders; it has seven or fourteen
+holes bored as illustrated on its circumference. When
+fourteen or eighteen cylinders are used the holes are<span class='pagenum'><a name="Page_475" id="Page_475">[475]</a></span>
+bored in two distinct planes, and offset in relation one to
+the other.</p>
+
+<p>The cylinders of the small engine which have a bore
+of 4<sup>3</sup>&#8260;<sub>10</sub> inches and a stroke of 4<sup>7</sup>&#8260;<sub>10</sub> inches, are machined
+out of the solid bar of steel until the thickness of the walls
+is only 1.5 millimeters&mdash;.05905 inch, or practically <sup>1</sup>&#8260;<sub>16</sub> inch.
+Each one has twenty-two fins which gradually taper down
+as the region of greatest pressure is departed from. In
+addition to carrying away heat, the fins assist in strengthening
+the walls of the cylinder. The barrel of the cylinder
+is slipped into the hole bored for it on the circumference
+of the crank-case and secured by a locking member
+in the nature of a stout compression ring, sprung onto a
+groove on the base of the cylinder within the crank chamber.
+On each lateral face of the crank chamber are seven
+holes, drilled right through the chamber parallel with the
+crank-shaft. Each one of these holes receives a stout
+locking-pin of such a diameter that it presses against
+the split rings of two adjacent cylinders; in addition
+each cylinder is fitted with a key-way. This construction
+is not always followed, some of the early Gnome engines
+using the same system of cylinder retention as used on
+the latest &#8220;monosoupape&#8221; pattern.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig201" id="Fig201"></a>
+<img src="images/illo471.png" alt="Fig. 201" width="400" height="451" />
+<p class="caption">Fig. 201.&mdash;Sectional View of Early Type Gnome Cylinder and Piston
+Showing Construction and Application of Inlet and Exhaust Valves.</p></div>
+
+<p>The exhaust valve is mounted in the cylinder head,
+<a href="#Fig201">Fig. 201</a>, its seating being screwed in by means of a
+special box spanner. On the fourteen-cylinder model the
+valve is operated directly by an overhead rocker arm
+with a gun metal rocker at its extremity coming in contact
+with the extremity of the valve stem. As in standard
+motor car practice, the valve is opened under the lift of
+the vertical push rod, actuated by the cam. The distinctive
+feature is the use of a four-blade leaf spring with
+a forked end encircling the valve stems and pressing
+against a collar on its extremity. On the seven-cylinder
+model the movement is reversed, the valve being opened
+on the downward pull of the push rod, this lifting the
+outer extremity of the main rocker arm, which tips a
+secondary and smaller rocker arm in direct contact with<span class='pagenum'><a name="Page_476" id="Page_476">[476]</a></span>
+the extremity of the valve stem. The springs are the
+same in each case. The two types are compared at A
+and B, <a href="#Fig202">Fig. 202</a>.</p>
+
+<p class='pagenum' style="margin-top: -1.5em;"><a name="Page_477" id="Page_477">[477]</a></p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig202" id="Fig202"></a>
+<img src="images/illo472.png" alt="Fig. 202" width="600" height="367" />
+<p class="caption">Fig. 202.&mdash;Details of Old Style Gnome Motor Inlet and Exhaust Valve Construction and Operation.</p></div>
+
+<p>The pistons, like the cylinders, are machined out of
+the solid bar of nickel steel, and have a portion of their
+wall cut away, so that the two adjacent ones will not
+come together at the extremity of their stroke. The head<span class='pagenum'><a name="Page_478" id="Page_478">[478]</a></span>
+of the piston is slightly reduced in diameter and is provided
+with a groove into which is fitted a very light
+L-section brass split ring; back of this ring and carried
+within the groove is sprung a light steel compression
+ring, serving to keep the brass ring in expansion. As
+already mentioned, the intake valves are automatic, and
+are mounted in the head of the piston as outlined at <a href="#Fig202">Fig.
+202</a>, C. The valve seating is in halves, the lower portion
+being made to receive the wrist-pin and connecting rod,
+and the upper portion, carrying the valve, being screwed
+into it. The spring is composed of four flat blades, with
+the hollowed stem of the automatic valve passing through
+their center and their two extremities attached to small
+levers calculated to give balance against centrifugal force.
+The springs are naturally within the piston, and are lubricated
+by splash from the crank chamber. They are of
+a delicate construction, for it is necessary that they shall
+be accurately balanced so as to have no tendency to fly
+open under the action of centrifugal force. The intake
+valve is withdrawn by the use of special tools through the
+cylinder head, the exhaust valve being first dismounted.</p>
+
+<p class='pagenum' style="margin-top: -1.5em;"><a name="Page_479" id="Page_479">[479]</a></p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig203" id="Fig203"></a>
+<img src="images/illo474.png" alt="Fig. 203" width="600" height="393" />
+<p class="caption">Fig. 203.&mdash;The Gnome Fourteen-Cylinder 100 Horse-Power Aviation Engine.</p></div>
+
+<p>The fourteen-cylinder motor shown at <a href="#Fig203">Fig. 203</a>, has a
+two-throw crank-shaft with the throws placed at 180 degrees,
+each one receiving seven connecting rods. The
+parts are the same as for the seven-cylinder motor, the
+larger one consisting of two groups placed side by side.
+For each group of seven-cylinders there is one main connecting
+rod, together with six auxiliary rods. The main
+connecting rod, which, like the others, is of H section, has
+machined with it two L-section rings bored with six holes&mdash;51<sup>1</sup>&#8260;<sub>2</sub>
+degrees apart to take the six other connecting
+rods. The cage of the main connecting rod carries two
+ball races, one on either side, fitting onto the crank-pin
+and receiving the thrust of the seven connecting rods.
+The auxiliary connecting rods are secured in position in
+each case by a hollow steel pin passing through the two
+rings. It is evident that there is a slightly greater angularity
+for the six shorter rods, known as auxiliary connecting<span class='pagenum'><a name="Page_480" id="Page_480">[480]</a></span>
+rods, than for the longer main rods; this does not
+appear to have any influence on the running of the motor.</p>
+
+<p>Coming to the manner in which the earliest design exhaust
+valves are operated on the old style motor, this at
+first sight appears to be one of the most complicated
+parts of the motor, probably because it is one in which
+standard practice is most widely departed from. Within
+the cylindrical casing bolted to the rear face of the crank-case
+are seven, thin flat-faced steel rings, forming female
+cams. Across a diameter of each ring is a pair of projecting
+rods fitting in brass guides and having their
+extremities terminating in a knuckle eye receiving the
+adjustable push rods operating the overhead rocker arms
+of the exhaust valve. The guides are not all in the same
+plane, the difference being equal to the thickness of the
+steel rings, the total thickness being practically 2 inches.
+Within the female cams is a group of seven male cams
+of the same total thickness as the former and rotating
+within them. As the boss of the male cam comes into
+contact with the flattened portion of the ring forming
+the female cam, the arm is pushed outward and the exhaust
+valve opened through the medium of the push-rod
+and overhead rocker. This construction was afterwards
+changed to seven male cams and simple valve operating
+plunger and roller cam followers as shown at <a href="#Fig204">Fig. 204</a>.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig204" id="Fig204"></a>
+<img src="images/illo476.png" alt="Fig. 204" width="400" height="547" />
+<p class="caption">Fig. 204.&mdash;Cam and Cam-Gear Case of the Gnome Seven-Cylinder
+Revolving Engine.</p></div>
+
+<p>On the face of the crank-case of the fourteen-cylinder
+motor opposite to the valve mechanism is a bolted-on end
+plate, carrying a pinion for driving the two magnetos
+and the two oil pumps, and having bolted to it the distributor
+for the high-tension current. Each group of
+seven-cylinders has its own magneto and lubricating
+pump. The two magnetos and the two pumps are mounted
+on the fixed platform carrying the stationary crank-shaft,
+being driven by the pinion on the revolving crank chamber.
+The magnetos are geared up in the proportion of
+4 to 7. Mounted on the end plate back of the driving
+pinion are the two high-tension distributor plates, each
+one with seven brass segments let into it and connection<span class='pagenum'><a name="Page_481" id="Page_481">[481]</a></span>
+made to the plugs by means of plain brass wire. The
+wire passes through a hole in the plug and is then
+wrapped round itself, giving a loose connection.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig205" id="Fig205"></a>
+<img src="images/illo477.png" alt="Fig. 205" width="400" height="217" />
+<p class="caption">Fig. 205.&mdash;Diagrams Showing Why An Odd Number of Cylinders is Best
+for Rotary Cylinder Motors.</p></div>
+
+<p><span class='pagenum'><a name="Page_482" id="Page_482">[482]</a></span>A good many people doubtless wonder why rotary engines
+are usually provided with an odd number of cylinders
+in preference to an even number. It is a matter of
+even torque, as can easily be understood from the accompanying
+diagram. <a href="#Fig205">Fig. 205</a>, A, represents a six-cylinder
+rotary engine, the radial lines indicating the cylinders.
+It is possible to fire the charges in two ways, firstly, in
+rotation, 1, 2, 3, 4, 5, 6, thus having six impulses in one
+revolution and none in the next; or alternately, 1, 3, 5, 2,
+4, 6, in which case the engine will have turned through
+an equal number of degrees between impulses 1 and 3,
+and 3 and 5, but a greater number between 5 and 2, even
+again between 2 and 4, 4 and 6, and a less number between
+6 and 1, as will be clearly seen on reference to the
+diagram. Turning to <a href="#Fig205">Fig. 205</a>, B, which represents a
+seven-cylinder engine. If the cylinders fire alternately
+it is obvious that the engine turns through an equal
+number of degrees between each impulse, thus, 1, 3, 5, 7,
+2, 4, 6, 1, 3, etc. Thus supposing the engine to be revolving,
+the explosion takes place as each alternate cylinder
+passes, for instance, the point 1 on the diagram, and the
+ignition is actually operated in this way by a single
+contact.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig206" id="Fig206"></a>
+<img src="images/illo478.png" alt="Fig. 206" width="400" height="369" />
+<p class="caption">Fig. 206.&mdash;Simple Carburetor Used On Early Gnome Engines Attached
+to Fixed Crank-Shaft End.</p></div>
+
+<p><span class='pagenum'><a name="Page_483" id="Page_483">[483]</a></span>The crank-shaft of the Gnome, as already explained,
+is fixed and hollow. For the seven- and nine-cylinder
+motors it has a single throw, and for the fourteen- and
+eighteen-cylinder models has two throws at 180 degrees.
+It is of the built-up type, this being necessary on account
+of the distinctive mounting of the connecting rods. The
+carburetor shown at <a href="#Fig206">Fig. 206</a> is mounted at one end of
+the stationary crank-shaft, and the mixture is drawn in
+through a valve in the piston as already explained. There
+is neither float chamber nor jet. In many of the tests
+made at the factory it is said the motor will run with the
+extremity of the gasoline pipe pushed into the hollow<span class='pagenum'><a name="Page_484" id="Page_484">[484]</a></span>
+crank-shaft, speed being regulated entirely by increasing
+or decreasing the flow through the shut-off valve in the
+base of the tank. Even under these conditions the motor
+has been throttled down to run at 350 revolutions without
+misfiring. Its normal speed is 1,000 to 1,200 revolutions
+a minute. Castor oil is used for lubricating the
+engine, the oil being injected into the hollow crank-shaft
+through slight-feed fittings by a mechanically operated
+pump which is clearly shown in sectional diagrams at
+<a href="#Fig207">Fig. 207</a>.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig207" id="Fig207"></a>
+<img src="images/illo479.png" alt="Fig. 207" width="400" height="325" />
+<p class="caption">Fig. 207.&mdash;Sectional Views of the Gnome Oil Pump.</p></div>
+
+<p>The Gnome is a considerable consumer of lubricant,
+the makers&#8217; estimate being 7 pints an hour for the 100
+horse-power motor; but in practice this is largely exceeded.
+The gasoline consumption is given as 300 to 350
+grammes per horse-power. The total weight of the fourteen-cylinder
+motor is 220 pounds without fuel or lubricating<span class='pagenum'><a name="Page_485" id="Page_485">[485]</a></span>
+oil. Its full power is developed at 1,200 revolutions,
+and at this speed about 9 horse-power is lost in
+overcoming air resistance to cylinder rotation.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig208" id="Fig208"></a>
+<img src="images/illo480.png" alt="Fig. 208" width="450" height="416" />
+<p class="caption">Fig. 208.&mdash;Simplified Diagram Showing Gnome Motor Magneto Ignition
+System.</p></div>
+
+<p>While the Gnome engine has many advantages, on the
+other hand, the head resistance offered by a motor of this
+type is considerable; there is a large waste of lubricating
+oil due to the centrifugal force which tends to throw the
+oil away from the cylinders; the gyroscopic effect of
+the rotary motor is detrimental to the best working of the
+aeroplane, and moreover it requires about seven per cent.
+of the total power developed by the motor to drive the
+revolving cylinders around the shaft. Of necessity, the<span class='pagenum'><a name="Page_486" id="Page_486">[486]</a></span>
+compression of this type of motor is rather low, and an
+additional disadvantage manifests itself in the fact that
+there is as yet no satisfactory way of muffling the rotary
+type of motor.</p>
+
+<h3><a name="SecXII_6" id="SecXII_6"></a>GNOME &#8220;MONOSOUPAPE&#8221; TYPE</h3>
+
+<p>The latest type of Gnome engine is known as the
+&#8220;monosoupape&#8221; type because but one valve is used in
+the cylinder head, the inlet valve in the piston being dispensed
+with on account of the trouble caused by that
+member on earlier engines. The construction of this
+latest type follows the lines established in the earlier
+designs to some extent and it differs only in the method
+of charging. The very rich mixture of gas and air is
+forced into the crank-case through the jet inside the
+crank-shaft, and enters the cylinder when the piston is
+at its lowest position, through the half-round openings
+in the guiding flange and the small holes or ports machined
+in the cylinder and clearly shown at <a href="#Fig210">Fig. 210</a>.
+The returning piston covers the port, and the gas is compressed
+and fired in the usual way. The exhaust is
+through a large single valve in the cylinder head, which
+gives rise to the name &#8220;monosoupape,&#8221; or single-valve
+motor, and this valve also remains open a portion of the
+intake stroke to admit air into the cylinder and dilute
+the rich gas forced in from the crank-case interior.
+Aviators who have used the early form of Gnome say
+that the inlet valve in the piston type was prone to catch
+on fire if any valve defect materialized, but the &#8220;monosoupape&#8221;
+pattern is said to be nearly free of this danger.
+The bore of the 100 horse-power nine-cylinder engine is
+110 mm., the piston stroke 150 mm. Extremely careful
+machine work and fitting is necessary. In many parts,
+tolerances of less than <span class="nowrap">.0004&#8242;&#8242;</span> (four ten thousandths of
+an inch) are all that are allowed. This is about one-sixth
+the thickness of the average human hair, and in
+other parts the size must be absolutely standard, no
+appreciable variation being allowable. The manufacture<span class='pagenum'><a name="Page_487" id="Page_487">[487]</a></span>
+of this engine establishes new mechanical standards of
+engine production in this country. Much machine work
+is needed in producing the finished components from the
+bar and forging.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig209" id="Fig209"></a>
+<img src="images/illo482.jpg" alt="Fig. 209" width="400" height="445" />
+<p class="caption">Fig. 209.&mdash;The G. V. Gnome &#8220;Monosoupape&#8221; Nine-Cylinder Rotary Engine
+Mounted on Testing Stand.</p></div>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig210" id="Fig210"></a>
+<img src="images/illo483.png" alt="Fig. 210" width="600" height="344" />
+<p class="caption">Fig. 210.&mdash;Sectional View Showing Construction of General Vehicle Co. &#8220;Monosoupape&#8221; Gnome
+Engine.</p></div>
+
+<p>The cylinders, for example, are machined from 6 inch
+solid steel bars, which are sawed into blanks 11 inches
+in length and weighing about 97 pounds. The first operation
+is to drill a 2<sup>1</sup>&#8260;<sub>16</sub> inch hole through the center of the
+block. A heavy-duty drilling machine performs this<span class='pagenum'><a name="Page_489" id="Page_489">[489]</a></span><span class='pagenum'><a name="Page_488" id="Page_488">[488]</a></span>
+work, then the block goes to the lathe for further operations.
+<a href="#Fig211">Fig. 211</a> shows six stages of the progress of a
+cylinder, a few of the intermediate steps being omitted.
+These give, however, a good idea of the work done. The
+turning of the gills, or cooling flanges, is a difficult proposition,
+owing to the depth of the cut and the thin metal
+that forms the gills. This operation requires the utmost
+care of tools and the use of a good lubricant to prevent<span class='pagenum'><a name="Page_490" id="Page_490">[490]</a></span>
+the metal from tearing as the tools approach their full
+depth. These gills are only 0.6 mm., or 0.0237 in., thick
+at the top, tapering to a thickness of 1.4 mm. (0.0553 in.)
+at the base, and are 16 mm. (0.632 in.) deep. When the
+machine work is completed the cylinder weighs but 5<sup>1</sup>&#8260;<sub>2</sub>
+pounds.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig211" id="Fig211"></a>
+<img src="images/illo484.jpg" alt="Fig. 211" width="400" height="478" />
+<p class="caption">Fig. 211.&mdash;How a Gnome Cylinder is Reduced from Solid Chunk of Steel
+Weighing 97 Pounds to Finished Cylinder Weighing 5<sup>1</sup>&#8260;<sub>2</sub> Pounds.</p></div>
+
+<h3>GNOME FUEL SYSTEM, IGNITION AND LUBRICATION</h3>
+
+<p>The following description of the fuel supply, ignition
+and oiling of the &#8220;monosoupape,&#8221; or single valve Gnome,
+is taken from &#8220;The Automobile.&#8221;</p>
+
+<p>Gasoline is fed to the engine by means of air pressure
+at 5 pounds per sq. in., which is produced by the air
+pump on the engine clearly shown at <a href="#Fig210">Fig. 210</a>. A pressure
+gauge convenient to the operator indicates this pressure,
+and a valve enables the operator to control it. No
+carburetor is used. The gasoline flows from the tank
+through a shut-off valve near the operator and through
+a tube leading through the hollow crank-shaft to a spray
+nozzle located in the crank-case. There is no throttle
+valve, and as each cylinder always receives the same
+amount of air as long as the atmospheric pressure is the
+same, the output cannot be varied by reducing the fuel
+supply, except within narrow limits. A fuel capacity of
+65 gallons is provided. The fuel consumption is at the
+rate of 12 U. S. gallons per hour.</p>
+
+<p>The high-tension magnetos, with double cam or two
+break per revolution interrupter, is located on the thrust
+plate in an inverted position, and is driven at such a
+speed as to produce nine sparks for every two revolutions;
+that is, at 2<sup>1</sup>&#8260;<sub>4</sub> times engine speed. A Splitdorf
+magneto is fitted. There is no distributor on the magneto.
+The high-tension collector brush of the magneto
+is connected to a distributor brush holder carried in the
+bearer plate of the engine. The brush in this brush
+holder is pressed against a distributor ring of insulating
+material molded in position in the web of a gear wheel<span class='pagenum'><a name="Page_491" id="Page_491">[491]</a></span>
+keyed to the thrust plate, which gear serves also for
+starting the engine by hand. Molded in this ring of insulating
+material are nine brass contact sectors, connecting
+with contact screws at the back side of the gear,
+from which bare wires connect to the spark-plugs. The
+distributor revolves at engine speed, instead of at half
+engine speed as on ordinary engines, and the distributor
+brush is brought into electrical connection with each
+spark-plug every time the piston in the cylinder in which
+this spark-plug is located approaches the outer dead
+center. However, on the exhaust stroke no spark is being
+generated in the magneto, hence none is produced at the
+spark-plug.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig212" id="Fig212"></a>
+<img src="images/illo486.jpg" alt="Fig. 212" width="450" height="303" />
+<p class="caption">Fig. 212.&mdash;The Gnome Engine Cam-Gear Case, a Fine Example of Accurate
+Machine Work.</p></div>
+
+<p>Ordinarily the engine is started by turning on the
+propeller, but for emergency purposes as in seaplanes or
+for a quick &#8220;get away&#8221; if landing inadvertently in
+enemy territory, a hand starting crank is provided. This
+is supported in bearings secured to the pressed steel
+carriers of the engine and is provided with a universal<span class='pagenum'><a name="Page_492" id="Page_492">[492]</a></span>
+joint between the two supports so as to prevent binding
+of the crank in the bearings due to possible distortion
+of the supports. The gear on this starting crank and the
+one on the thrust plate with which it meshes are cut
+with helical teeth of such hand that the starting pinion
+is thrown out of mesh as soon as the engine picks up its
+cycle. A coiled spring surrounds part of the shaft of the
+starting crank and holds it out of gear when not in use.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig213" id="Fig213"></a>
+<img src="images/illo487.jpg" alt="Fig. 213" width="450" height="494" />
+<p class="caption">Fig. 213.&mdash;G. V. Gnome &#8220;Monosoupape,&#8221; with Cam-Case Cover Removed to
+Show Cams and Valve-Operating Plungers with Roller Cam Followers.</p></div>
+
+<p>Lubricating oil is carried in a tank of 25 gallon capacity,
+and if this tank has to be placed in a low position<span class='pagenum'><a name="Page_493" id="Page_493">[493]</a></span>
+it is connected with the air-pressure line, so that the
+suction of the oil pump is not depended upon to get the
+oil to the pump. From the bottom of the oil tank a pipe
+leads to the pump inlet. There are two outlets from the
+pump, each entering the hollow crank-shaft, and there is
+a branch from each outlet pipe to a circulation indicator
+convenient to the operator. One of the oil leads feeds
+to the housing in the thrust plate containing the two rear
+ball bearings, and the other lead feeds through the crank-pin
+to the cams, as already explained.</p>
+
+<p>Owing to the effect of centrifugal force and the fact
+that the oil is not used over again, the oil consumption
+of a revolving cylinder engine is considerably higher than
+that of a stationary cylinder engine. Fuel consumption
+is also somewhat higher, and for this reason the revolving
+cylinder engine is not so well suited for types of airplanes
+designed for long trips, as the increased weight
+of supplies required for such trips, as compared with
+stationary cylinder type motors, more than offsets the
+high weight efficiency of the engine itself. But for short
+trips, and especially where high speed is required, as in
+single seated scout and battle planes or &#8220;avions de
+chasse,&#8221; as the French say, the revolving cylinder engine
+has the advantage. The oil consumption of the Gnome
+engine is as high as 2.4 gallon per hour. Castor oil is
+used for lubrication because it is not cut by the gasoline
+mist present in the engine interior as an oil of mineral
+derivation would be.</p>
+
+<h3><a name="SecXII_7" id="SecXII_7"></a>GERMAN &#8220;GNOME&#8221; TYPE ENGINE</h3>
+
+<p>A German adaptation of the Gnome design is shown
+at <a href="#Fig214">Fig. 214</a>. This is known as the Bayerischen Motoren
+Gesellschaft engine and the type shown is an early design
+rated at 50 horse-power. The bore is 110 mm., the stroke
+is 120 mm., and it is designed to run at a speed of 1,200
+R.&nbsp;P.&nbsp;M. It is somewhat similar in design to the early
+Gnome &#8220;valve-in-piston&#8221; design except that two valves<span class='pagenum'><a name="Page_495" id="Page_495">[495]</a></span>
+<span class='pagenum'><a name="Page_494" id="Page_494"></a></span>are carried in the piston top instead of one. The valve
+operating arrangement is different also, as a single four
+point cam is used to operate the seven exhaust valves.
+It is driven by epicyclic gearing, the cam being driven by
+an internal gear machined integrally with it, the cam
+being turned at <sup>7</sup>&#8260;<sub>8</sub> times the engine speed. Another
+feature is the method of holding the cylinders on the
+crank-case. The cylinder is provided with a flange that
+registers with a corresponding member of the same diameter
+on the crank-case. A U section, split clamping ring
+is bolted in place as shown, this holding both flanges
+firmly together and keeping the cylinder firmly seated
+against the crank-case flange. The &#8220;monosoupape&#8221; type
+has also been copied and has received some application
+in Germany, but the most successful German airplanes
+are powered with six-cylinder vertical engines such as
+the Benz and Mercedes.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig214" id="Fig214"></a>
+<img src="images/illo489.png" alt="Fig. 214" width="600" height="396" />
+<p class="caption">Fig. 214.&mdash;The 50 Horse-Power Rotary Bayerischen Motoren Gesellschaft Engine, a German Adaptation of the Early
+Gnome Design.</p></div>
+
+<h3><a name="SecXII_8" id="SecXII_8"></a>THE LE RHONE MOTOR</h3>
+
+<p>The Le Rhone motor is a radial revolving cylinder
+engine that has many of the principles which are incorporated
+in the Gnome but which are considered to be an
+improvement by many foreign aviators. Instead of having
+but one valve in the cylinder head, as the latest type
+&#8220;monosoupape&#8221; Gnome has, the Le Rhone has two valves,
+one for intake and one for exhaust in each cylinder. By
+an ingenious rocker arm and tappet rod arrangement
+it is possible to operate both valves with a single push
+rod. Inlet pipes communicate with the crank-case at one
+end and direct the fresh gas to the inlet valve cage at the
+other. Another peculiarity in the design is the method
+of holding the cylinders in place. Instead of having a
+vertically divided crank-case as the Gnome engine has
+and clamping both halves of the case around the cylinders,
+the crank-case of the Le Rhone engine is in the
+form of a cylinder having nine bosses provided with
+threaded openings into which the cylinders are screwed.<span class='pagenum'><a name="Page_496" id="Page_496">[496]</a></span>
+A thread is provided at the base of each cylinder and
+when the cylinder has been screwed down the proper
+amount it is prevented from further rotation about its
+own axis by a substantial lock nut which screws down
+against the threaded boss on the crank-case. The external
+appearance of the Le Rhone type motor is clearly
+shown at <a href="#Fig215">Fig. 215</a>, while the general features of construction
+are clearly outlined in the sectional views given
+at <a href="#Fig216">Figs. 216</a> and <a href="#Fig217">217</a>.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig215" id="Fig215"></a>
+<img src="images/illo491.jpg" alt="Fig. 215" width="400" height="479" />
+<p class="caption">Fig. 215.&mdash;Nine-Cylinder Revolving Le Rhone Type Aviation Engine.</p></div>
+
+<p class='pagenum' style="margin-top: -1.5em;"><a name="Page_497" id="Page_497">[497]</a></p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig216" id="Fig216"></a>
+<p class="leftlink"><a href="images/large492.png">Large<br />image<br />(96 kB).</a></p>
+<img src="images/illo492.png" alt="Fig. 216" width="600" height="370" />
+<p class="caption">Fig. 216.&mdash;Part Sectional Views of Le Rhone Rotary Cylinder Engine, Showing Method of Cylinder Retention,
+Valve Operation and Novel Crank Disc Assembly.</p></div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig217" id="Fig217"></a>
+<p class="leftlink"><a href="images/large493.png">Large<br />image<br />(98 kB).</a></p>
+<img src="images/illo493.png" alt="Fig. 217" width="500" height="419" />
+<p class="caption">Fig. 217.&mdash;Side Sectional View of Le Rhone Aviation Engine.</p></div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig218" id="Fig218"></a>
+<img src="images/illo494.png" alt="Fig. 218" width="500" height="481" />
+<p class="caption">Fig. 218.&mdash;View Showing Le Rhone Valve Action and Connecting Rod
+Big End Arrangement.</p></div>
+
+<p><span class='pagenum'><a name="Page_498" id="Page_498">[498]</a></span>The two main peculiarities of this motor are the
+method of valve actuation by two large cams and the
+distinctive crank-shaft and connecting rod big end construction.
+The connecting rods are provided with &#8220;feet&#8221;
+or shoes on the end which fit into grooves lined with
+bearing metal which are machined into crank discs
+revolving on ball bearings and which are held together so
+that the connecting rod big ends are sandwiched between
+them by clamping screws. This construction is a modification
+of that used on the Anzani six-cylinder radial
+engine. There are three grooves machined in each crank
+disc and three connecting rod big ends run in each pair
+of grooves. The details of this construction can be readily
+ascertained by reference to explanatory diagrams at
+<a href="#Fig218">Figs. 218</a> and <a href="#Fig219">219</a>, A.
+Three of the rods which work<span class='pagenum'><a name="Page_499" id="Page_499">[499]</a></span>
+in the groove nearest the crank-pin are provided with
+short shoes as shown at <a href="#Fig219">Fig. 219</a>, B. The short shoes
+are used on the rods employed in cylinders number 1,
+4, and 7. The set of connecting rods that work in the
+central grooves are provided with medium-length shoes
+and actuate the pistons in cylinders numbers 3, 6, and 9.
+The three rods that work in the outside grooves have still
+longer shoes and are employed in cylinders numbers 2,
+5, and 8. The peculiar profile of the inlet and exhaust
+cam plates are shown at C, <a href="#Fig219">Fig. 219</a>, while the construction
+of the wrist-pin, wrist-pin bushing and piston are
+clearly outlined at the sectional view at E. The method<span class='pagenum'><a name="Page_500" id="Page_500">[500]</a></span>
+of valve actuation is clearly outlined at <a href="#Fig220">Fig. 220</a>, which
+shows an end section through the cam case and also
+a partial side elevation showing one of the valve operating
+levers which is fulcrumed at a central point and which
+has a roller at one end bearing on one cam while the
+roller or cam follower at the other end bears on the other
+cam. The valve rocker arm actuating rod is, of course,
+operated by this simple lever and is attached to it in
+such a way that it can be pulled down to depress the
+inlet valve and pushed up to open the exhaust valve.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig219" id="Fig219"></a>
+<img src="images/illo495.png" alt="Fig. 219" width="500" height="530" />
+<p class="caption">Fig. 219.&mdash;Diagrams Showing Important Components of Le Rhone Motor.</p></div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig220" id="Fig220"></a>
+<p class="leftlink"><a href="images/large496.png">Large<br />image<br />(95 kB).</a></p>
+<img src="images/illo496.png" alt="Fig. 220" width="400" height="534" />
+<p class="caption">Fig. 220.&mdash;How the Cams of the Le Rhone Motor Can Operate Two Valves
+with a Single Push Rod.</p></div>
+
+<p><span class='pagenum'><a name="Page_501" id="Page_501">[501]</a></span>A carburetor of peculiar construction is employed in
+the Le Rhone engine, this being a very simple type as
+outlined at <a href="#Fig221">Fig. 221</a>. It is attached to the threaded end
+of the hollow crank-shaft by a right and left coupling.<span class='pagenum'><a name="Page_502" id="Page_502">[502]</a></span>
+The fuel is pumped to the spray nozzle, the opening in
+which is controlled by a fuel regulating needle having
+a long taper which is lifted out of the jet opening when
+the air-regulating slide is moved. The amount of fuel
+supplied the carburetor is controlled by a special needle
+valve fitting which combines a filter screen and which is
+shown at B. In regulating the speed of the Le Rhone
+engine, there are two possible means of controlling the
+mixture, one by altering the position of the air-regulating
+slide, which also works the metering needle in the jet, and
+the other by controlling the amount of fuel supplied to
+the spray nozzle through the special fitting provided for
+that purpose.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig221" id="Fig221"></a>
+<img src="images/illo497.png" alt="Fig. 221" width="450" height="345" />
+<p class="caption">Fig. 221.&mdash;The Le Rhone Carburetor at A and Fuel Supply Regulating
+Device at B.</p></div>
+
+<p>In considering the action of this engine one can refer
+to <a href="#Fig222">Fig. 222</a>. The crank O. M. is fixed, while the cylinders
+can turn about the crank-shaft center O and the piston<span class='pagenum'><a name="Page_503" id="Page_503">[503]</a></span>
+turns around the crank-pin M, because of the eccentricity
+of the centers of rotation the piston will reciprocate in
+the cylinders. This distance is at its maximum when
+the cylinder is above O and at a minimum when it is
+above M, and the difference between these two positions
+is equal to the stroke, which is twice the distance of the
+crank-throw O, M. The explosion pressure resolves itself
+into the force F exerted along the line of the connecting
+rod A, M, and also into a force N, which tends to make
+the cylinders rotate around point O in the direction of
+the arrow. An odd number of cylinders acting on one
+crank-pin is desirable to secure equally spaced explosions,
+as the basic action is the same as the Gnome engine.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig222" id="Fig222"></a>
+<img src="images/illo498.png" alt="Fig. 222" width="500" height="330" />
+<p class="caption">Fig. 222.&mdash;Diagrams Showing Le Rhone Motor Action and Firing Order.</p></div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig223" id="Fig223"></a>
+<img src="images/illo499.png" alt="Fig. 223" width="500" height="484" />
+<p class="caption">Fig. 223.&mdash;Diagram Showing Positions of Piston in Le Rhone Rotary
+Cylinder Motor.</p></div>
+
+<p>The magneto is driven by a gear having 36 teeth attached
+to crank-case which meshes with 16-tooth pinion
+on armature. The magneto turns at 2.25 times crank-case
+speed. Two cams, one for inlet, one for exhaust,
+are mounted on a carrying member and act on nine
+rocker arms which are capable of giving a push-and-pull<span class='pagenum'><a name="Page_504" id="Page_504">[504]</a></span>
+motion to the valve-actuating rocker-operating rods. A
+gear driven by the crank-case meshes with a larger member
+having internal teeth carried by the cam carrier.
+Each cam has five profiles and is mounted in staggered
+relation to the other. These give the nine fulcrumed
+levers the proper motion to open the inlet and exhaust
+valves at the proper time. The cams are driven at
+<sup>45</sup>&#8260;<sub>50</sub> or <sup>9</sup>&#8260;<sub>10</sub> of the motor speed. The cylinder dimensions
+and timing follows; the weight can be approximated by
+figuring 3 pounds per horse-power.</p>
+
+<p class='pagenum'><a name="Page_505" id="Page_505">[505]</a></p>
+
+<table class="fsize80" summary="Table p. 505-1">
+
+<tr>
+<td class="right padr1">80</td>
+<td class="left padr5">H.P.</td>
+<td class="right padr1">105</td>
+<td class="left padr5">M/M bore</td>
+<td class="right padr1"><span class="nowrap">4.20&#8242;&#8242;</span></td>
+<td class="left">bore.</td>
+</tr>
+
+<tr>
+<td colspan="2">&nbsp;</td>
+<td class="right padr1">140</td>
+<td class="left padr5">M/M stroke</td>
+<td class="right padr1"><span class="nowrap">5.60&#8242;&#8242;</span></td>
+<td class="left">stroke.</td>
+</tr>
+
+<tr>
+<td class="right padr1">110</td>
+<td class="left padr5">H.P.</td>
+<td class="right padr1">112</td>
+<td class="left padr5">M/M bore</td>
+<td class="right padr1"><span class="nowrap">4.48&#8242;&#8242;</span></td>
+<td class="left">bore.</td>
+</tr>
+
+<tr>
+<td colspan="2">&nbsp;</td>
+<td class="right padr1">170</td>
+<td class="left padr5">M/M stroke</td>
+<td class="right padr1"><span class="nowrap">6.80&#8242;&#8242;</span></td>
+<td class="left">stroke.</td>
+</tr>
+
+</table>
+
+<table class="fsize80" style="line-height: 1em;" summary="Table p. 505-2">
+
+<tr>
+<td class="left padr0">Timing&mdash;</td>
+<td class="left padl0 padr5">Intake valve opening, lag</td>
+<td class="right">18&deg;</td>
+<td class="center symb">&#9131;</td>
+<td rowspan="5" class="left padl2 padr2">110 H.P.</td>
+<td class="right">18&deg;</td>
+<td class="center symb">&#9131;</td>
+<td rowspan="5" class="left padl2 padr2">80 H.P.</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left padl0 padr5">Intake valve closing, lag</td>
+<td class="right">35&deg;</td>
+<td class="center symb">&#9134;</td>
+<td class="right">35&deg;</td>
+<td class="center symb">&#9134;</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left padl0 padr5">Exhaust valve opening, lead</td>
+<td class="right">55&deg;</td>
+<td class="center symb">&#9132;</td>
+<td class="right">45&deg;</td>
+<td class="center symb">&#9132;</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left padl0 padr5">Exhaust valve closing, lag</td>
+<td class="right">5&deg;</td>
+<td class="center symb">&#9134;</td>
+<td class="right">5&deg;</td>
+<td class="center symb">&#9134;</td>
+</tr>
+
+<tr>
+<td>&nbsp;</td>
+<td class="left padl0 padr5">Ignition time advance</td>
+<td class="right">26&deg;</td>
+<td class="center symb">&#9133;</td>
+<td class="right">26&deg;</td>
+<td class="center symb">&#9133;</td>
+</tr>
+
+</table>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig224" id="Fig224"></a>
+<img src="images/illo500.png" alt="Fig. 224" width="500" height="456" />
+<p class="caption">Fig. 224.&mdash;Diagrams Showing Valve Timing of Le Rhone Aviation Engine.</p></div>
+
+<h3><a name="SecXII_9" id="SecXII_9"></a>THE RENAULT AIR-COOLED VEE ENGINE</h3>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig225" id="Fig225"></a>
+<img src="images/illo501.png" alt="Fig. 225" width="400" height="536" />
+<p class="caption">Fig. 225.&mdash;Diagrams Showing How Cylinder Cooling is Effected in
+Renault Vee Engines.</p></div>
+
+<p>Air-cooled stationary engines are rarely used in airplanes,
+but the Renault Fr&egrave;res of France have for several
+years manufactured a complete series of such engines of
+the general design shown at <a href="#Fig225">Fig. 225</a>, ranging from
+a<span class='pagenum'><a name="Page_506" id="Page_506">[506]</a></span>
+low-powered one developed eight or nine years ago and
+rated at 40 and 50 horse-power, to later eight-cylinder
+models rated at 70 horse-power and a twelve-cylinder, or
+twin six, rated at 90 horse-power. The cylinders are of
+cast iron and are furnished with numerous cooling ribs<span class='pagenum'><a name="Page_507" id="Page_507">[507]</a></span>
+which are cast integrally. The cylinder heads are separate
+castings and are attached to the cylinder as in early
+motorcycle engine practice, and serve to hold the cylinder
+in place on the aluminum alloy crank-case by a cruciform
+yoke and four long hold-down bolts (<a href="#Fig226">Fig. 226</a>). The
+pistons are of cast steel and utilize piston rings of cast
+iron. The valves are situated on the inner side of the
+cylinder head, the arrangement being unconventional in
+that the exhaust valves are placed above the inlet. The
+inlet valves seat in an extension of the combustion head
+and are actuated by direct push rod and cam in the usual
+manner while an overhead gear in which rockers are operated<span class='pagenum'><a name="Page_508" id="Page_508">[508]</a></span>
+by push rods is needed to actuate the exhaust valves.
+The valve action is clearly shown in <a href="#Fig226">Figs. 226</a> and <a href="#Fig227">227</a>.
+The air stream by which the cylinders are cooled is produced
+by a centrifugal or blower type fan of relatively
+large diameter which is mounted on the end of a crank-shaft
+and the air blast is delivered from this blower into
+an enclosed space between the cylinder from which it
+escapes only after passing over the cooling fins. In
+spite of the fact that considerable prejudice exists against
+air-cooling fixed cylinder engines, the Renault has given
+very good service in both England and France.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig226" id="Fig226"></a>
+<img src="images/illo502.png" alt="Fig. 226" width="450" height="442" />
+<p class="caption">Fig. 226.&mdash;End Sectional View of Renault Air-Cooled Aviation Engine.</p></div>
+
+<p class='pagenum' style="margin-top: -1.5em;"><a name="Page_509" id="Page_509">[509]</a></p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig227" id="Fig227"></a>
+<img src="images/illo504.png" alt="Fig. 227" width="600" height="368" />
+<p class="caption">Fig. 227.&mdash;Side Sectional View of Renault Twelve-Cylinder Air-Cooled Aviation Engine Crank-Case, Showing Use
+of Plain and Ball Bearings for Crank-Shaft Support.</p></div>
+
+<p>As will be seen by the sectional view at <a href="#Fig227">Fig. 227</a>, the
+steel crank-shaft is carried in a combination of plain
+bearings inside the crank-case and by ball bearings at the
+ends. Owing to air cooling, special precautions are taken
+with the lubrication system, though the lubrication is not
+forced or under high pressure. An oil pump of the gear-wheel
+type delivers oil from the sump at the bottom of the
+crank-case to a chamber above, from which the oil flows
+by gravity along suitable channels to the various main
+bearings. It flows from the bearings into hollow rings
+fastened to the crank-webs, and the oil thrown from the
+whirling connecting rod big ends bathes the internal
+parts in an oil mist. In the eight-cylinder designs ignition
+is effected by a magneto giving four sparks per revolution
+and is accordingly driven at engine speed. In the
+twelve-cylinder machine two magnetos of the ordinary
+revolving armature or two-spark type, each supplying
+six cylinders, are fitted as outlined at <a href="#Fig228">Fig. 228</a>. The
+carburetor is a float feed form. Warm air is supplied
+for Winter and damp weather by air pipes surrounding
+the exhaust pipes. The normal speed of the Renault
+engine is 1,800 R.&nbsp;P.&nbsp;M., but as the propeller is mounted
+upon an extension of the cam-shaft the normal propeller
+speed is but half that of the engine, which makes it possible
+to use a propeller of large diameter and high efficiency.
+Owing to the air cooling, but low compression
+may be used, this being about 60 pounds per square inch,<span class='pagenum'><a name="Page_510" id="Page_510">[510]</a></span>
+which, of course, lowers the mean effective pressure and
+makes the engine less efficient than water-cooled forms
+where it is possible to use compression pressure of 100<span class='pagenum'><a
+name="Page_512" id="Page_512">[512]</a></span><span class='pagenum'><a name="Page_511" id="Page_511"></a></span>
+or more pounds per square inch. The 70 horse-power
+engine has cylinders with a bore of 3.78 inches and a
+stroke of 5.52 inches. Its weight is given as 396 pounds,
+when in running order, which figures 5.7 pounds per
+horse-power. The same cylinder size is used on the
+twelve-cylinder 100 horse-power and the stroke is the
+same. This engine in running order weighs 638 pounds,
+which figures approximately 6.4 pounds per B.&nbsp;H.&nbsp;P.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig228" id="Fig228"></a>
+<img src="images/illo505.png" alt="Fig. 228" width="400" height="546" />
+<p class="caption">Fig. 228.&mdash;End View of Renault Twelve-Cylinder Engine Crank-Case,
+Showing Magneto Mounting.</p></div>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig229" id="Fig229"></a>
+<img src="images/illo506.png" alt="Fig. 229" width="600" height="364" />
+<p class="caption">Fig. 229.&mdash;Diagram Outlining Renault Twelve-Cylinder Engine Ignition System.</p></div>
+
+<h3><a name="SecXII_10" id="SecXII_10"></a>SIMPLEX MODEL &#8220;A&#8221; HISPANO-SUIZA</h3>
+
+<p>The Model A is of the water-cooled four-cycle Vee
+type, with eight cylinders, 4.7245 inch bore by 5.1182 inch
+stroke, piston displacement 718 cubic inches. At sea-level
+it develops 150 horse-power at 1,450 R.&nbsp;P.&nbsp;M. It can
+be run successfully at much higher speeds, depending
+on propeller design and gearing, developing proportionately
+increased power. The weight, including carburetor,
+two magnetos, propeller hub, starting magneto and crank,
+but without radiator, water or oil or exhaust pipes, is
+445 pounds. Average fuel consumption is .5 pound per
+horse-power hour and the oil consumption at 1,450 R.&nbsp;P.&nbsp;M.
+is three quarts per hour. The external appearance is
+shown at <a href="#Fig230">Fig. 230</a>.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig230" id="Fig230"></a>
+<img src="images/illo508.jpg" alt="Fig. 230" width="500" height="298" />
+<p class="caption">Fig. 230.&mdash;The Simplex Model A Hispano-Suiza Aviation Engine, a Very
+Successful Form.</p></div>
+
+<p>Four cylinders are contained in each block, which is
+of built-up construction; the water jackets and valve
+ports are cast aluminum and the individual cylinders
+heat-treated steel forgings threaded into the bored holes
+of the aluminum castings. Each block after assembly is
+given a number of protective coats of enamel, both inside
+and out, baked on. Coats on the inside are applied
+under pressure. The pistons are aluminum castings,
+ribbed. Connecting rods are tubular, of the forked type.
+One rod bears directly on the crank-pin; the other rod
+has a bearing on the outside of the one first mentioned.</p>
+
+<p>The crank-shaft is of the five-bearing type, very short,
+stiff in design, bored for lightness and for the oiling
+system. The crank-shaft extension is tapered for the<span class='pagenum'><a name="Page_513" id="Page_513">[513]</a></span>
+French standard propeller hub, which is keyed and
+locked to the shaft. This makes possible instant change
+of propellers. The case is in two halves divided on the
+center line of the crank-shaft, the bearings being fitted
+between the upper and lower sections. The lower half
+is deep, providing a large oil reservoir and stiffening
+the engine. The upper half is simple and provides magneto
+supports on extension ledges of the two main faces.
+The valves are of large diameter with hollow stems,
+working in cast iron bushings. They are directly operated
+by a single hollow cam-shaft located over the valves. The
+cam-shafts are driven from the crank-shaft by vertical
+shafts and bevel gears. The cam-shafts, cams and heads
+of the valve stems are all enclosed in oil-tight removable
+housings of cast aluminum.</p>
+
+<p>Oiling is by a positive pressure system. The oil is
+taken through a filter and steel tubes cast in the case
+to main bearings, through crank-shaft to crank-pins.
+The fourth main bearing is also provided with an oil
+lead from the system and through tubes running up the
+end of each cylinder block, oil is provided for the cam-shafts,<span class='pagenum'><a name="Page_514" id="Page_514">[514]</a></span>
+cams and bearings. The surplus oil escapes
+through the end of the cam-shaft where the driving gears
+are mounted, and with the oil that has gathered in the
+top casing, descends through the drive shaft and gears
+to the sump.</p>
+
+<p>Ignition is by two eight-cylinder magnetos firing two
+spark-plugs per cylinder. The magnetos are driven
+from each of the two vertical shafts by small bevel
+pinions meshing in bevel gears. The carburetor is
+mounted between the two cylinder blocks and feeds the
+two blocks through aluminum manifolds which are partly
+water-jacketed. The engine can be equipped with a
+geared hand crank-starting device.</p>
+
+<h3>STURTEVANT MODEL 5A 140 HORSE-POWER ENGINE</h3>
+
+<p>These motors are of the eight-cylinder &#8220;V&#8221; type, four-stroke
+cycle, water-cooled, having a bore of 4 inches and
+a stroke of 5<sup>1</sup>&#8260;<sub>2</sub> inches, equivalent to 102 mm. &times; 140 mm.
+The normal operating speed of the crank-shaft is 2,000
+R.&nbsp;P.&nbsp;M. The propeller shaft is driven through reducing
+gears which can be furnished in different gear ratios.
+The standard ratio is 5:3, allowing a propeller speed of
+1,200 R.&nbsp;P.&nbsp;M.</p>
+
+<p>The construction of the motor is such as to permit
+of the application of a direct drive. The change from the
+direct drive to gear drive, or vice versa, can be accomplished
+in approximately one hour.</p>
+
+<p>The cylinders are cast in pairs from an aluminum
+alloy and are provided with steel sleeves, carefully fitted
+into each cylinder. A perfect contact is secured between
+cylinder and sleeve; at the same time a sleeve can be
+replaced without injury to the cylinder proper. No difficulties
+due to expansion occur on account of the rapid
+transmission of heat and the fact that the sleeve is always
+at higher temperature than the cylinder. A moulded
+copper asbestos gasket is placed between the cylinder
+and the head, permitting the cooling water to circulate<span class='pagenum'><a name="Page_515" id="Page_515">[515]</a></span>
+freely and at the same time insuring a tight joint. The
+cylinder heads are cast in pairs from an aluminum alloy
+and contain ample water passages for circulation of
+cooling water over the entire head. Trouble due to hot
+valves is thereby eliminated, a most important consideration
+in the operation of an aeroplane motor. The
+water jacket of the head corresponds to the water jacket
+of the cylinders and large openings in both allow the
+unobstructed circulation of the cooling water. The cylinder
+heads and cylinders are both held to the base by six
+long bolts. The valves are located in the cylinder heads
+and are mechanically operated. The valves and valve
+springs are especially accessible and of such size as to
+permit high volumetric efficiency. The valves are constructed
+of hardened tungsten steel, the heads and stems
+being made from one piece. The valve rocker arms
+located on the top of the cylinder are provided with
+adjusting screws. A check nut enables the adjusting
+screw to be securely locked in position, once the correct
+clearance has been determined. The rocker arm bearings
+are adequately lubricated by a compression grease cup.
+Cam-rollers are interposed between the cams and the
+push rods in order to reduce the side thrust on the push
+rods.</p>
+
+<p>A system of double springs is employed which greatly
+reduces the stress on each spring and insures utmost
+reliability. A spring of extremely large diameter returns
+the valve; a second spring located at the cylinder base
+handles the push rod linkage. These springs, which
+operate under low stress, are made from the best of steel
+and are given a special double heat treatment. The
+pistons are made from a special aluminum alloy; are
+deeply ribbed in the head for cooling and strength and
+provided with two piston rings. These pistons are exceedingly
+light weight in order to minimize vibration and
+prevent wear on the bearings. The piston pin is made of
+chrome nickel steel, bored hollow and hardened. It is
+allowed to turn, both in piston and connecting rod. The<span class='pagenum'><a name="Page_516" id="Page_516">[516]</a></span>
+piston rings are of special design, developed after years
+of experimenting in aeronautical engines.</p>
+
+<p>The connecting rods are of &#8220;H&#8221; section, machined
+all over from forgings of a special air-hardening chrome
+nickel steel which, after being heat treated has a tensile
+strength of 280,000 pounds per square inch. They are
+consequently very strong and yet unusually light, and
+being machined all over are of absolutely uniform section,
+which gives as nearly perfect balance as can be obtained.
+The big ends are lined with white metal and the small
+ends are bushed with phosphor bronze. The connecting
+rods are all alike and take their bearings side by side on
+the crank-pin, the cylinders being offset to permit of
+this arrangement. The crank-shaft is machined from
+the highest grade chrome nickel steel, heat treated in
+order to obtain the best properties of this material.
+It is 2<sup>1</sup>&#8260;<sub>4</sub> inches in diameter (57 mm.) and bored hollow
+throughout, insuring maximum strength with minimum
+weight. It is carried in three large, bronze-backed white
+metal bearings. A new method of producing these bearings
+insures a perfect bond between the two metals and
+eliminates breakage.</p>
+
+<p>The base is cast from an aluminum alloy. Great
+strength and rigidity is combined with light weight. The
+sides extend considerably below the center line of the
+crank-shaft, providing an extremely deep section. At
+all highly stressed points, deep ribs are provided to distribute
+the load evenly and eliminate bending. The lower
+half of the base is of cast aluminum alloy of extreme
+lightness. This collects the lubricating oil and acts as
+a small reservoir for same. An oil-filtering screen of
+large area covers the entire surface of the sump. The
+propeller shaft is carried on two large annular ball bearings
+driven from the crank-shaft by hardened chrome
+nickel steel spur gears. These gears are contained within
+an oil-tight casing integral with the base on the opposite
+end from the timing gears. A ball-thrust bearing
+is provided on the propeller shaft to take the thrust of<span class='pagenum'><a name="Page_517" id="Page_517">[517]</a></span>
+a propeller or tractor, as the case may be. In case of the
+direct drive a stub shaft is fastened direct to the crank-shaft
+and is fitted with a double thrust bearing.</p>
+
+<p>The cam-shaft is contained within the upper half of
+the base between the two groups of cylinders, and is
+supported in six bronze bearings. It is bored hollow
+throughout and the cams are formed integral with the
+shaft and ground to the proper shape and finish. An
+important development in the shape of cams has resulted
+in a maintained increase of power at high speeds. The
+gears operating the cam-shaft, magneto, oil and water
+pumps are contained within an oil-tight casing and operate
+in a bath of oil.</p>
+
+<p>Lubrication is of the complete forced circulating system,
+the oil being supplied to every bearing under high
+pressure by a rotary pump of large capacity. This is
+operated by gears from the crank-shaft. The oil passages
+from the pump to the main bearings are cast integral
+with the base, the hollow crank-shaft forming a passage
+through the connecting rod bearings and the hollow cam-shaft
+distributing the oil to the cam-shaft bearings. The
+entire surface of the lower half of the base is covered
+with a fine mesh screen through which the oil passes
+before reaching the pump. Approximately one gallon of
+oil is contained within the base and this is continually
+circulated through an external tank by a secondary pump
+operated by an eccentric on the cam-shaft. This also
+draws fresh oil from the external tank which can be made
+of any desired capacity.</p>
+
+<h3>SPECIFICATIONS&mdash;MODEL 5A TYPE 8</h3>
+
+<ul class="barelist">
+<li>Horse-power rating, 140 at 2,000 R.&nbsp;P.&nbsp;M.</li>
+<li>Bore, 4 inches = 102 mm.</li>
+<li>Stroke, 5<sup>1</sup>&#8260;<sub>2</sub> inches = 140 mm.</li>
+<li>Number of cylinders, 8.</li>
+<li>Arrangement of cylinders, &#8220;V.&#8221;</li>
+<li><span class='pagenum'><a name="Page_518" id="Page_518">[518]</a></span>Cooling, water. Circulation by centrifugal pump.</li>
+<li>Cycle, four stroke.</li>
+<li>Ignition (double), 2 Bosch or Splitdorf magnetos.</li>
+<li>Carburetor, Zenith duplex. Water jacket manifold.</li>
+<li>Oiling system, complete forced. Circulating gear pump.</li>
+<li>Normal crank-shaft speed, 2,000 R.&nbsp;P.&nbsp;M.</li>
+<li>Propeller shaft, <sup>3</sup>&#8260;<sub>5</sub> crank-shaft speed at normal, 1,200 R.&nbsp;P.&nbsp;M.</li>
+<li>Stated power at <span class="nowrap">30&#8242;&#8242;</span> barometer, 140 B.&nbsp;H.&nbsp;P.</li>
+<li>Stated weight with all accessories but without water, gasoline or oil, 514 pounds = 234 kilos.</li>
+<li>Weight per B.&nbsp;H.&nbsp;P., 3.7 pounds = 1.68 kilos.</li>
+<li>Stated weight with all accessories with water, 550 pounds = 250 kilos.</li>
+<li>Weight per B.&nbsp;H.&nbsp;P. with water, 3.95 pounds = 1.79 kilos.</li>
+</ul>
+
+<h3><a name="SecXII_11" id="SecXII_11"></a>THE CURTISS AVIATION MOTORS</h3>
+
+<p>The Curtiss OX motor has eight cylinders, 4-inch
+bore, 5-inch stroke, delivers 90 horse-power at 1,400 turns,
+and the weight turns out at 4.17 pounds per horse-power.
+This motor has cast iron cylinders with monel metal
+jackets, overhead inclined valves operated by means of
+two rocker arms, push-and-pull rods from the central
+cam-shaft located in the crank-case. The cam and push
+rod design is extremely ingenious and the whole valve
+construction turns out very light. This motor is an
+evolution from the early Curtiss type motor which was
+used by Glenn Curtiss when he won the Gordon Bennett
+Cup at Rheims. A slightly larger edition of this type
+motor is the OXX-5, as shown at <a href="#Fig231">Figs. 231</a> and <a href="#Fig232">232</a>,
+which has cylinders 4<sup>1</sup>&#8260;<sub>4</sub> inches by 5 inches, delivers 100
+horse-power at 1,400 turns and has the same fuel and
+oil consumption as the OX type motor, namely, .60 pound
+of fuel per brake horse-power hour and .03 pound of
+lubricating oil per brake horse-power hour.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig231" id="Fig231"></a>
+<img src="images/illo514.jpg" alt="Fig. 231" width="450" height="399" />
+<p class="caption">Fig. 231.&mdash;The Curtiss OXX-5 Aviation Engine is an Eight-Cylinder Type
+Largely Used on Training Machines.</p></div>
+
+<p>The Curtiss Company have developed in the last
+two years a larger-sized motor now known as the V-2,
+which was originally rated at 160 horse-power and which<span class='pagenum'><a name="Page_519" id="Page_519">[519]</a></span>
+has since been refined and improved so that the motor
+gives 220 horse-power at 1,400 turns, with a fuel consumption
+of <sup>52</sup>&#8260;<sub>100</sub> of a pound per brake horse-power hour
+and an oil consumption of .02 of a pound per brake
+horse-power hour. This larger motor has a weight of 3.45
+pounds per horse-power and is now said to be giving
+very satisfactory service. The V-2 motor has drawn
+steel cylinders, with a bore of 5 inches and a stroke of
+7 inches, with a steel water jacket top and a monel metal
+cylindrical jacket, both of which are brazed on to the
+cylinder barrel itself. Both these motors use side by
+side connecting rods and fully forced lubrication. The
+cam-shafts act as a gallery from which the oil is distributed
+to the cam-shaft bearings, the main crank-shaft<span class='pagenum'><a name="Page_520" id="Page_520">[520]</a></span>
+bearings, and the gearing. Here again we find extremely
+short rods, which, as before mentioned, enables the height
+and the consequent weight of construction to be very
+much reduced. For ordinary flying at altitudes of 5,000
+to 6,000 feet, the motors are sent out with an aluminum
+liner, bolted between the cylinder and the crank-case in
+order to give a compression ratio which does not result
+in pre-ignition at a low altitude. For high flying, however,
+these aluminum liners are taken out and the compression<span class='pagenum'><a name="Page_521" id="Page_521">[521]</a></span>
+volume is decreased to about 18.6 per cent. of
+the total volume.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig232" id="Fig232"></a>
+<img src="images/illo515.jpg" alt="Fig. 232" width="500" height="546" />
+<p class="caption">Fig. 232.&mdash;Top and Bottom Views of the Curtiss OXX-5 100 Horse-Power
+Aviation Engine.</p></div>
+
+<p>The Curtiss Aeroplane Company announces that it has
+recently built, and is offering, a twelve-cylinder <span class="nowrap">5&#8242;&#8242;</span>
+&times; <span class="nowrap">7&#8242;&#8242;</span>
+motor, which was designed for aeronautical uses primarily.
+This engine is rated at 250 horse-power, but it is
+claimed to develop 300 at 1,400 R.&nbsp;P.&nbsp;M. Weights&mdash;Motor,
+1,125 pounds; radiator, 120 pounds; cooling water, 100
+pounds; propeller, 95 pounds.</p>
+
+<p>Gasoline Consumption per Horse-power Hour, <sup>6</sup>&#8260;<sub>10</sub>
+pounds.</p>
+
+<p>Oil Consumption per Hour at Maximum Speed&mdash;2
+pints.</p>
+
+<p>Installation Dimensions&mdash;Overall length, 84<sup>5</sup>&#8260;<sub>8</sub> inches;
+overall width, 34<sup>1</sup>&#8260;<sub>8</sub> inches; overall depth, 40 inches;
+width at bed, 30<sup>1</sup>&#8260;<sub>2</sub> inches; height from bed, 21<sup>1</sup>&#8260;<sub>8</sub> inches;
+depth from bed, 18<sup>1</sup>&#8260;<sub>2</sub> inches.</p>
+
+<h3><a name="SecXII_12" id="SecXII_12"></a>THOMAS-MORSE MODEL 88 ENGINE</h3>
+
+<p>The Thomas-Morse Aircraft Corporation of Ithaca,
+N. Y., has produced a new engine, Model 88, bearing a
+close resemblance to the earlier model. The main features
+of that model have been retained; in fact, many parts
+are interchangeable in the two engines. Supported by
+the great development in the wide use of aluminum, the
+Thomas engineers have adopted this material for cylinder
+construction, which adoption forms the main departure
+from previous accepted design.</p>
+
+<p>The marked tendency to-day toward a higher speed
+of rotation has been conclusively justified, in the opinion
+of the Thomas engineers, by the continued reliable performance
+of engines with crank-shafts operating at speeds
+near 2,000 revolutions per minute, driving the propeller
+through suitable gearing at the most efficient speed.
+High speed demands that the closest attention be paid
+to the design of reciprocating and rotating parts and
+their adjacent units. Steel of the highest obtainable<span class='pagenum'><a name="Page_522" id="Page_522">[522]</a></span>
+tensile strength must be used for connecting rods and
+piston pins, that they may be light and yet retain a
+sufficient factor of safety. Piston design is likewise
+subjected to the same strict scrutiny. At the present
+day, aluminum alloy pistons operate so satisfactorily
+that they may be said to have come to stay.</p>
+
+<p>The statement often made in the past, that the gearing
+down of an engine costs more in the weight of reduction
+gears and propeller shaft than is warranted by
+the increase in horse-power, is seldom heard to-day.</p>
+
+<p>The mean effective pressure remaining the same, the
+brake horse-power of any engine increases as the speed.
+That is, an engine delivering 100 brake horse-power at
+1,500 revolutions per minute will show 133 brake horse-power
+at 2,000 revolutions per minute, an increase of 33
+brake horse-power. To utilize this increase in horse-power,
+a matter of some fifteen pounds must be spent
+in gearing and another fifteen perhaps on larger valves,
+bearings, etc. Two per cent. may be assumed lost in
+the gears. In other words, the increase in horse-power
+due to increasing the speed has been attained at the
+expense of about one pound per brake horse-power.</p>
+
+<p>The advantages of the eight-cylinder engine over the
+six and twelve, briefly stated, are: lower weight per horse-power,
+shorter length, simpler and stiffer crank-shaft,
+cam-shaft and crank-case, and simpler and more direct
+manifold arrangement. As to torque, the eight is superior
+to the six, and yet in practice not enough inferior
+to the twelve to warrant the addition of four more
+cylinders. It must, however, be recognized that the
+eight is subject to the action of inherent unbalanced
+inertia couples, which set up horizontal vibrations, impossible
+of total elimination. These vibrations are functions
+of the reciprocating weights, which, as already
+mentioned, are cut down to the minimum. Vibrations
+due to the elasticity of crank-case, crank-shaft, etc., can
+be and are reduced in the Thomas engine to minor
+quantities by ample webbing of the crank-case and judicious<span class='pagenum'><a name="Page_523" id="Page_523">[523]</a></span>
+use of metal elsewhere. All things considered,
+there is actually so little difference to be discerned between
+the balance of a properly designed eight-cylinder
+engine and that of a six or twelve as to make a discussion
+of the pros and cons more one of theory than
+of practice.</p>
+
+<p>The main criticisms of the L head cylinder engine are
+that it is less efficient and heavier. This is granted, as it
+relates to cylinders alone. More thorough investigation,
+however, based on the main desideratum, weight-power
+ratio, leads us to other conclusions, particularly with
+reference to high speed engines. The valve gear must
+not be forgotten. A cylinder cannot be taken completely
+away from its component parts and judged, as to its
+weight value, by itself alone. A part away from the whole
+becomes an item unimportant in comparison with the
+whole. The valve gear of a high speed engine is a too
+often overlooked feature. The stamp of approval has
+been made by high speed automobile practice upon the
+overhead cam-shaft drive, with valves in the cylinder
+head operated direct from the cam-shaft or by means of
+valve lifters or short rockers.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig233" id="Fig233"></a>
+<img src="images/illo519.jpg" alt="Fig. 233" width="450" height="558" />
+<p class="caption">Fig. 233.&mdash;End View of Thomas-Morse 150 Horse-Power Aluminum Cylinder
+Aviation Motor Having Detachable Cylinder Heads.</p></div>
+
+<p>The overhead cam-shaft mechanism applied to an
+eight-cylinder engine calls for two separate cam-shafts
+carried above and supported by the cylinders in an oil-tight
+housing, and driven by a series of spur gears or
+bevels from the crank-shaft. It is patent that this valve
+gearing is heavy and complicated in comparison with
+the simple moving valve units of the L head engine,
+which are operated from one single cam-shaft, housed
+rigidly in the crank-case. The inherently lower volumetric
+efficiency of the L head engine is largely overcome
+by the use of a properly designed head, large valves and
+ample gas passages. Again, the customary use of a dual
+ignition system gives to the L head a relatively better
+opportunity for the advantageous placing of spark-plugs,
+in order that better flame propagation and complete
+combustion may be secured.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig234" id="Fig234"></a>
+<img src="images/illo520.jpg" alt="Fig. 234" width="500" height="349" />
+<p class="caption">Fig. 234.&mdash;Side View of Thomas-Morse High Speed 150 Horse-Power
+Aviation Motor with Geared Down Propeller Drive.</p></div>
+
+<p><span class='pagenum'><a name="Page_524" id="Page_524">[524]</a></span>The
+Thomas Model 88 engine is 4<sup>1</sup>&#8260;<sub>8</sub> inch bore and
+5<sup>1</sup>&#8260;<sub>2</sub> inch stroke. The cylinders and cylinder heads are
+of aluminum, and as steel liners are used in the cylinders
+the pistons are also made of aluminum. This engine is
+actually lighter than the earlier model of less power.
+It weighs but 525 pounds, with self-starter. The general<span class='pagenum'><a name="Page_525" id="Page_525">[525]</a></span>
+features of design can be readily ascertained by study
+of the illustrations: <a href="#Fig233">Fig. 233</a>, which shows an end view;
+<a href="#Fig234">Fig. 234</a>, which is a side view, and <a href="#Fig235">Fig. 235</a>, which outlines
+the reduction gear-case and the propeller shaft
+supporting bearings.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig235" id="Fig235"></a>
+<img src="images/illo521.jpg" alt="Fig. 235" width="400" height="403" />
+<p class="caption">Fig. 235.&mdash;The Reduction Gear-Case of Thomas-Morse 150 Horse-Power
+Aviation Motor, Showing Ball Bearing and Propeller Drive Shaft Gear.</p></div>
+
+<h3><a name="SecXII_13" id="SecXII_13"></a>SIXTEEN-VALVE DUESENBERG ENGINE</h3>
+
+<p>This engine is a four-cylinder, <span class="nowrap">4<sup>3</sup>&#8260;<sub>4</sub>&#8242;&#8242;</span>
+&times; <span class="nowrap">7&#8242;&#8242;,</span> 125 horse-power
+at 2,100 R.&nbsp;P.&nbsp;M. of the crank-shaft and 1,210
+R.&nbsp;P.&nbsp;M. of the propeller. Motors are sold on above
+rating; actual power tests prove this motor capable of
+developing 140 horse-power at 2,100 R.&nbsp;P.&nbsp;M. of the
+motor. The exact weight with magneto, carburetor, gear
+reduction and propeller hub, as illustrated, 509 pounds;
+without gear reduction, 436 pounds. This motor has
+been produced as a power plant weighing 3.5 pounds per
+horse-power, yet nothing has been sacrificed in rigidity
+and strength. At its normal speed it develops 1 horse-power<span class='pagenum'><a name="Page_526" id="Page_526">[526]</a></span>
+for every 3.5 cubic inches piston displacement.
+Cylinders are semi-steel, with aluminum plates enclosing
+water jackets. Pistons specially ribbed and made of
+Magnalite aluminum compound. Piston rings are special
+Duesenberg design, being three-piece rings. Valves are
+tungsten steel, <span class="nowrap">1<sup>15</sup>&#8260;<sub>16</sub>&#8242;&#8242;</span>
+inlets and <span class="nowrap">2&#8242;&#8242;</span> exhausts, two of each
+to each cylinder. Arranged horizontally in the head,
+allowing very thorough water-jacketing. Inlet valves in
+cages. Exhaust valves, seating directly in the cylinder
+head, are removable through the inlet valve holes. Valve
+stems lubricated by splash in the valve action covers.
+Valve rocker arms forged with cap screw and nut at<span class='pagenum'><a name="Page_527" id="Page_527">[527]</a></span>
+upper end to adjust clearance. Entirely enclosed by
+aluminum housing, as is entire valve mechanism. Connecting
+rods are tubular, chrome nickel steel, light and
+strong. Crank-shaft is one-piece forging, hollow bored,
+2<sup>1</sup>&#8260;<sub>2</sub>-inch diameter at main bearings. Connecting rod
+bearings, 2<sup>1</sup>&#8260;<sub>4</sub>-inch diameter, 3 inches long. Front main
+bearing, 3<sup>1</sup>&#8260;<sub>2</sub> inches long; intermediate main bearing,
+3<sup>1</sup>&#8260;<sub>2</sub> inches long; rear main bearing, 4 inches long. Crank-case
+of aluminum, barrel type, oil pan on bottom removable.
+Hand hole plates on both sides. Strongly webbed.</p>
+
+<p>The oiling system of this sixteen-valve Duesenberg
+motor is one of its vital features. An oil pump located
+in the base and submerged in oil forces oil through cored
+passages to the three main bearings, then through tubes
+under each connecting rod into which the rod dips. The
+oil is thrown off from these and lubricates every part of
+the motor. This constitutes the main oiling system; it is
+supplemented by a splash system, there being a trough
+under each connecting rod into which the rod slips. The
+oil is returned to the main supply sump by gravity,
+where it is strained and re-used. Either system is in
+itself sufficient to operate the motor. A pressure gauge
+is mounted for observation on a convenient part of the
+system. A pressure of approximately 25 pounds is
+maintained by the pressure system, which insures efficient
+lubrication at all speeds of the motor. The troughs
+under the connecting rods are so constructed that no
+matter what the angle of flight may be, oil is retained
+in each individual trough so that each connecting rod
+can dip up its supply of oil at each revolution.</p>
+
+<h3><a name="SecXII_14" id="SecXII_14"></a>AEROMARINE SIX-CYLINDER VERTICAL MOTOR</h3>
+
+<p>These motors are four-stroke cycle, six-cylinder vertical
+type, with cylinder <span class="nowrap">4<sup>5</sup>&#8260;<sub>16</sub>&#8242;&#8242;</span> bore by <span class="nowrap">5<sup>1</sup>&#8260;<sub>8</sub>&#8242;&#8242;</span> stroke. The
+general appearance of this motor is shown in illustration
+at <a href="#Fig236">Fig. 236</a>. This engine is rated at 85-90 horse-power.
+All reciprocating and revolving parts of this<span class='pagenum'><a name="Page_528" id="Page_528">[528]</a></span>
+motor are made of the highest grades of steel obtainable
+as are the studs, nuts and bolts. The upper and lower
+parts of crank-case are made of composition aluminum
+casting. Lower crank-case is made of high grade aluminum
+composition casting and is bolted directly to the
+upper half. The oil reservoir in this lower half casting
+provides sufficient oil capacity for five hours&#8217; continuous
+running at full power. Increased capacity can be provided
+if needed to meet greater endurance requirements.
+Oil is forced under pressure to all bearings by means of
+high-pressured duplex-geared pumps. One side of this
+pump delivers oil under pressure to all the bearings,
+while the other side draws the oil from the splash case
+and delivers it to the main sump. The oil reservoir is
+entirely separate from the crank-case chamber. Under
+no circumstances will oil flood the cylinder, and the oiling
+system is not affected in any way by any angle of flight
+or position of motor. An oil pressure gauge is placed
+on instrument board of machine, which gives at all times<span class='pagenum'><a name="Page_529" id="Page_529">[529]</a></span>
+the pressure in oil system, and a sight glass at lower
+half of case indicates the amount of oil contained. The
+oil pump is external on magneto end of motor, and is
+very accessible. An external oil strainer is provided,
+which is removable in a few minutes&#8217; time without the
+loss of any oil. All oil from reservoir to the motor passes
+through this strainer. Pressure gauge feed is also attached
+and can be piped to any part of machine desired.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig236" id="Fig236"></a>
+<img src="images/illo523.jpg" alt="Fig. 236" width="500" height="329" />
+<p class="caption">Fig. 236.&mdash;The Six-Cylinder Aeromarine Engine.</p></div>
+
+<p>The cylinders are made of high-grade castings and
+are machined and ground accurately to size. Cylinders
+are bolted to crank-case with chrome nickel steel studs
+and nuts which securely lock cylinder to upper half of
+crank-case. The main retaining cylinder studs go
+through crank-case and support crank-shaft bearings so
+that crank-shaft and cylinders are tied together as one
+unit. Water jackets are of copper, <span class="nowrap"><sup>1</sup>&#8260;<sub>16</sub>&#8242;&#8242;</span> thick, electrically
+deposited. This makes a non-corrosive metal. Cooling
+is furnished by a centrifugal pump, which delivers 25
+gallons per minute at 1,400 R.&nbsp;P.&nbsp;M. Pistons are made
+cast iron, accurately machined and ground to exact dimensions,
+which are carefully balanced. Piston rings are
+semi-steel rings of Aeromarine special design.</p>
+
+<p><span class='pagenum'><a name="Page_530" id="Page_530">[530]</a></span>Connecting rods are of chrome nickel steel, H-section.
+Crank-shaft is made of chrome nickel steel, machined all
+over, and cut from solid billet, and is accurately balanced
+through the medium of balance weights being
+forged integral with crank. It is drilled for lightness and
+plugged for force feed lubrication. There are seven
+main bearings to crank-shaft. All bearings are of high-grade
+babbitt, die cast, and are interchangeable and easily
+replaced. The main bearings of the crank-shaft are
+provided with a single groove to take oil under pressure
+from pressure tube which is cast integral with case.
+Connecting rod bearings are of the same type. The
+gudgeon pin is hardened, ground and secured in connecting
+rod, and is allowed to work in piston. Cam-shaft
+is of steel, with cams forged integral, drilled for lightness
+and forced-feed lubrication, and is case-hardened.<span class='pagenum'><a name="Page_531" id="Page_531">[531]</a></span>
+The bearings of cam-shaft are of bronze. Magneto, two
+high-tension Bosch D. U. 6. The intake manifold for
+carburetors are aluminum castings and are so designed
+that each carburetor feeds three cylinders, thereby insuring
+easy flow of vapor at all speeds. Weight, 420 pounds.</p>
+
+<h3><a name="SecXII_15" id="SecXII_15"></a>WISCONSIN AVIATION ENGINES</h3>
+
+<p>The new six-cylinder Wisconsin aviation engines, one
+of which is shown at <a href="#Fig237">Fig. 237</a>, are of the vertical type,
+with cylinders in pairs and valves in the head. Dimensioned
+drawings of the six-cylinder vertical type are
+given at <a href="#Fig238">Figs. 238</a> and <a href="#Fig239">239</a>. The cylinders are made of
+aluminum alloy castings, are bored and machined and
+then fitted with hardened steel sleeves about <sup>1</sup>&#8260;<sub>16</sub> inch in
+thickness. After these sleeves have been shrunk into
+the cylinders, they are finished by grinding in place.
+Gray iron valve seats are cast into the cylinders. The
+valve seats and cylinders, as well as the valve ports, are<span class='pagenum'><a name="Page_532" id="Page_532">[532]</a></span>
+entirely surrounded by water jackets. The valves set
+in the heads at an angle of <span class="nowrap">25&deg;</span> from the vertical, are
+made of tungsten steel and are provided with double
+springs, the outer or main spring and the inner or auxiliary
+spring, which is used as a precautionary measure
+to prevent a valve falling into the cylinder in remote
+case of a main spring breaking. The cam-shaft is made
+of one solid forging, case-hardened. It is carried in an
+aluminum housing bolted to the top of the cylinders.
+This housing is split horizontally, the upper half carrying
+the chrome vanadium steel rocker levers. The lower half
+has an oil return trough cast integral, into which the
+excess oil overflows and then drains back to the crank-case.
+Small inspection plates are fitted over the cams
+and inner ends of the cam rocker levers. The cam-shaft
+runs in bronze bearings and the drive is through vertical
+shaft and bevel gears.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig237" id="Fig237"></a>
+<img src="images/illo525.jpg" alt="Fig. 237" width="400" height="580" />
+<p class="caption">Fig. 237.&mdash;The Wisconsin Aviation Engine, at Top, as Viewed from
+Carburetor Side. Below, the Exhaust Side.</p></div>
+
+<p>The crank-case is made of aluminum, the upper half<span class='pagenum'><a name="Page_533" id="Page_533">[533]</a></span>
+carrying the bearings for the crank-shaft. The lower
+half carries the oil sump in which all of the oil except
+that circulating through the system at the time is carried.
+The crank-shaft is made of chrome vanadium steel of
+an elastic limit of 115,000 pounds. The crank-pins and
+ends of the shaft are drilled for lightness and the cheeks
+are also drilled for oil circulation. The crank-shaft runs
+in bronze-backed, Fahrig metal-lined bearings, four in
+number. A double thrust bearing is also provided, so
+that the motor may be used either in a tractor or pusher
+type of machine. Outside of the thrust bearing an annular
+ball bearing is used to take the radial load of the
+propeller. The propeller is mounted on a taper. At the
+opposite end of the shaft a bevel gear is fitted which
+drives the cam-shaft, through a vertical shaft, and also
+drives the water and oil pumps and magnetos. All gears
+are made of chrome vanadium steel, heat-treated.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig238" id="Fig238"></a>
+<img src="images/illo526.png" alt="Fig. 238" width="400" height="534" />
+<p class="caption">Fig. 238.&mdash;Dimensioned End Elevation of Wisconsin Six Motor.</p></div>
+
+<p>The connecting rods are tubular and machined from
+chrome vanadium steel forgings. Oil tubes are fitted to
+the rods which carry the oil up to the wrist-pins and
+pistons. The rods complete with bushings weigh 5<sup>1</sup>&#8260;<sub>2</sub>
+pounds each. The pistons are made of aluminum alloy
+and are very light and strong, weighing only 2 pounds
+2 ounces each. Two leak-proof rings are fitted to each
+piston. The wrist-pins are hollow, of hardened steel,
+and are free to turn either in the piston or the rod. A
+bronze bushing is fitted in the upper end of the rod, but
+no bushing is fitted in the pistons, the hardened steel
+wrist-pins making an excellent bearing in the aluminum
+alloy.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig239" id="Fig239"></a>
+<img src="images/illo527.png" alt="Fig. 239" width="600" height="429" />
+<p class="caption">Fig. 239.&mdash;Dimensioned Side Elevation of Wisconsin Six Motor.</p></div>
+
+<p>The water circulation is by centrifugal pump, which
+is mounted at the lower end of the vertical shaft. The
+water is pumped through brass pipes to the lower end
+of the cylinder water jackets and leaves the upper end
+of the jackets just above the exhaust valves. The lubricating
+system is one of the main features of the engines,
+being designed to work with the motor at any angle.
+The oil is carried in the sump, from where it is taken<span class='pagenum'><a name="Page_534" id="Page_534">[534]</a></span>
+by the oil circulating pump through a strainer and forced
+through a header, extending the full length of the crank-case,
+and distributed to the main bearings. From the
+main bearings it is forced through the hollow crank-shaft
+to the connecting rod big ends and then through<span class='pagenum'><a name="Page_535" id="Page_535">[535]</a></span>
+tubes on the rods to wrist-pins and pistons. Another
+lead takes oil from the main header to the cam-shaft
+bearings. The oil forced out of the ends of the cam-shaft
+bearings fills pockets under the cams and in the
+cam rocker levers. The excess flows back through pipes
+and through the train of gears to the crank-case. A
+strainer is fitted at each end of the crank-case, through
+which the oil is drawn by separate pumps and returned
+to the sump. Either one of these pumps is large enough
+to take care of all of the return oil, so that the operation
+is perfect whether the motor is inclined up or down. No
+splash is used in the crank-case, the system being a
+full force feed. An oil level indicator is provided, showing
+the amount of oil in the sump at all times. The oil
+pressure in these motors is carried at ten pounds, a
+relief valve being fitted to hold the pressure constant.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig240" id="Fig240"></a>
+<img src="images/illo529.png" alt="Fig. 240" width="450" height="573" />
+<p class="caption">Fig. 240.&mdash;Power, Torque and Efficiency Curves of Wisconsin Aviation
+Motor.</p></div>
+
+<p>Ignition is by two Bosch magnetos, each on a separate
+set of plugs fired simultaneously on opposite sides of the
+cylinders. Should one magneto fail, the other would still
+run the engine at only a slight loss in power. The Zenith
+double carburetor is used, three cylinders being supplied
+by each carburetor. This insures a higher volumetric
+efficiency, which means more power, as there is no overlapping<span class='pagenum'><a name="Page_536" id="Page_536">[536]</a></span>
+of inlet valves whatever by this arrangement.
+All parts of these motors are very accessible. The water
+and oil pumps, carburetors, magnetos, oil strainer or
+other parts can be removed without disturbing other
+parts. The lower crank-case can be removed for inspection
+or adjustment of bearings, as the crank-shaft and
+bearing caps are carried by the upper half. The motor
+supporting lugs are also part of the upper crank-case.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig241" id="Fig241"></a>
+<img src="images/illo530.png" alt="Fig. 241" width="400" height="376" />
+<p class="caption">Fig. 241.&mdash;Timing Diagram, Wisconsin Aviation Engine.</p></div>
+
+<p>The six-cylinder motor, without carburetors or magnetos,
+weighs 547 pounds. With carburetor and magnetos,
+the weight is 600 pounds. The weight of cooling
+water in the motor is 38 pounds. The sump will carry
+4 gallons of oil, or about 28 pounds. A radiator can be
+furnished suitable for the motor, weighing 50 pounds.
+This radiator will hold 3 gallons of water or about 25
+pounds. The motor will drive a two-blade, 8 feet diameter
+by 6.25 feet pitch Paragon propeller 1400 revolutions
+per minute, developing 148 horse-power. The weight of
+this propeller is 42 pounds. This makes a total weight
+of motor, complete with propeller, radiator filled with
+water, but without lubricating oil, 755 pounds, or about
+5.1 pounds per horse-power for complete power plant.
+The fuel consumption is .5 pound per horse-power per
+hour. The lubricating oil consumption is .0175 pound
+per horse-power per hour, or a total of 2.6 pounds per
+hour at 1400 revolutions per minute. This would make
+the weight of fuel and oil, per hour&#8217;s run at full power
+at 1400 revolutions per minute, 76.6 pounds.</p>
+
+<h3>PRINCIPAL DIMENSIONS</h3>
+
+<p>Following are the principal dimensions of the six-cylinder
+motor:</p>
+
+<ul class="barelist">
+<li>Bore 5 inches.</li>
+<li>Stroke 6<sup>1</sup>&#8260;<sub>2</sub> inches.</li>
+<li>Crank-shaft diameter throughout 2 inches.</li>
+<li>Length of crank-pin and main bearings 3<sup>1</sup>&#8260;<sub>2</sub> inches.</li>
+<li><span class='pagenum'><a name="Page_537" id="Page_537">[537]</a></span>Diameter of valves 3
+inches (2<sup>3</sup>&#8260;<sub>4</sub> inches clear).</li>
+<li>Lift of valves <sup>1</sup>&#8260;<sub>2</sub> inch.</li>
+<li>Volume of compression space 22 per cent. of total.</li>
+<li>Diameter of wrist-pins 1<sup>3</sup>&#8260;<sub>16</sub> inches.</li>
+<li>Firing order 1-4-2-6-3-5.</li>
+</ul>
+
+<p>The horse-power developed at 1200 revolutions per
+minute is 130, at 1300 revolutions per minute 140, at
+1400 revolutions per minute 148. 1400 is the maximum
+speed at which it is recommended to run these motors.</p>
+
+<h3>TWELVE-CYLINDER ENGINE</h3>
+
+<p>A twelve-cylinder V-type engine <a href="#Fig242">illustrated</a>, is also
+being built by this company, similar in dimensions of
+cylinders to the six. The principal differences being in
+the drive to cam-shaft, which is through spur gears instead
+of bevel. A hinged type of connecting rod is used
+which does not increase the length of the motor and, at
+the same time, this construction provides for ample bearings.
+A double centrifugal water pump is provided for
+this motor, so as to distribute the water uniformly to
+both sets of cylinders. Four magnetos are used, two for
+each set of six cylinders. The magnetos are very accessibly
+located on a bracket on the spur gear cover. The
+carburetors are located on the outside of the motors,
+where they are very accessible, while the exhaust is in the
+center of the valley. The crank-shaft on the twelve is
+2<sup>1</sup>&#8260;<sub>2</sub> inches in diameter and the shaft is bored to reduce
+weight. Dimensioned drawings of the twelve-cylinder
+engine are given at <a href="#Fig242">Figs. 242</a> and <a href="#Fig243">243</a> and should prove
+useful for purposes of comparison with other motors.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig242" id="Fig242"></a>
+<img src="images/illo533.png" alt="Fig. 242" width="450" height="481" />
+<p class="caption">Fig. 242.&mdash;Dimensioned End View of Wisconsin Twelve-Cylinder Airplane
+Motor.</p></div>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig243" id="Fig243"></a>
+<img src="images/illo534.png" alt="Fig. 243" width="600" height="384" />
+<p class="caption">Fig. 243.&mdash;Dimensioned Side Elevation of Wisconsin Twelve-Cylinder Airplane
+Motor.</p></div>
+
+<h3><a name="SecXII_16" id="SecXII_16"></a>HALL-SCOTT AVIATION ENGINES</h3>
+
+<p>The following specifications of the Hall-Scott &#8220;Big
+Four&#8221; engines apply just as well to the six-cylinder
+vertical types which are practically the same in construction
+except for the structural changes necessary to accommodate
+the two extra cylinders. Cylinders are cast<span class='pagenum'><a name="Page_538" id="Page_538">[538]</a></span>
+separately from a special mixture of semi-steel, having
+cylinder head with valve seats integral. Special attention
+has been given to the design of the water jacket around
+the valves and head, there being two inches of water
+space above same. The cylinder is annealed, rough
+machined, then the inner cylinder wall and valve seats
+ground to mirror finish. This adds to the durability of
+the cylinder, and diminishes a great deal of the excess
+friction.</p>
+
+<p><span class='pagenum'><a name="Page_539" id="Page_539">[539]</a></span>Great care is taken in the casting and machining of
+these cylinders, to have the bore and walls concentric
+with each other. Small ribs are cast between outer and
+inner walls to assist cooling as well as to transfer stresses
+direct from the explosion to hold-down bolts which run
+from steel main bearing caps to top of cylinders. The
+cylinders are machined upon the sides so that when
+assembled on the crank-case with grooved hold-down
+washers tightened, they form a solid block, greatly assisting
+the rigidity of crank-case.</p>
+
+<p>The connecting rods are very light, being of the I
+beam type, milled from a solid Chrome nickel die forging.
+The caps are held on by two <span class="nowrap"><sup>1</sup>&#8260;<sub>2</sub>&#8242;&#8242;-20</span> thread Chrome nickel
+through bolts. The rods are first roughed out, then annealed.
+Holes are drilled, after which the rods are hardened
+and holes ground parallel with each other. The
+piston end is fitted with a gun metal bushing, while the
+crank-pin end carries two bronze serrated shells, which
+are tinned and babbitted hot, being broached to harden
+the babbitt. Between the cap and rod proper are placed<span class='pagenum'><a name="Page_540" id="Page_540">[540]</a></span>
+laminated shims for adjustment. Crank-cases are cast of
+the best aluminum alloy, hand scraped and sand blasted
+inside and out. The lower oil case can be removed without
+breaking any connections, so that the connecting rods
+and other working parts can readily be inspected. An
+extremely large strainer and dirt trap is located in the
+center and lowest point of the case, which is easily removed
+from the outside without disturbing the oil pump
+or any working parts. A Zenith carburetor is provided.
+Automatic valves and springs are absent, making the
+adjustment simple and efficient. This carburetor is not
+affected by altitude to any appreciable extent. A Hall-Scott
+device, covered by U. S. Patent No. 1,078,919, allows
+the oil to be taken direct from the crank-case and run
+around the carburetor manifold, which assists carburetion
+as well as reduces crank-case heat. Two waterproof four-cylinder
+Splitdorf &#8220;Dixie&#8221; magnetos are provided. Both
+magneto interruptors are connected to a rock shaft integral
+with the motor, making outside connections unnecessary.
+It is worthy of note that with this independent
+double magneto system, one complete magneto can become
+inoperative, and still the motor will run and continue to
+give good power.</p>
+
+<p>The pistons as provided in the A-7 engines are cast
+from a mixture of steel and gray iron. These are extremely
+light, yet provided with six deep ribs under the
+arch head, greatly aiding the cooling of the piston as well
+as strengthening it. The piston pin bosses are located
+very low in order to keep the heat from the piston head
+away from the upper end of the connecting rod, as well
+as to arrange them at the point where the piston fits the
+cylinder best. Three <span class="nowrap"><sup>1</sup>&#8260;<sub>4</sub>&#8242;&#8242;</span> rings are carried. The pistons
+as provided in the A-7a engines are cast from aluminum
+alloy. Four <span class="nowrap"><sup>1</sup>&#8260;<sub>4</sub>&#8242;&#8242;</span> rings are carried. In both piston types
+a large diameter, heat treated, Chrome nickel steel wrist-pin
+is provided, assembled in such a way as to assist the
+circular rib between the wrist-pin bosses to keep the
+piston from being distorted from the explosions.</p>
+
+<p><span class='pagenum'><a name="Page_541" id="Page_541">[541]</a></span>The oiling system is known as the high pressure type,
+oil being forced to the under side of the main bearings
+with from 5 to 30 points pressure. This system is not
+affected by extreme angles obtained in flying, or whether
+the motor is used for push or pull machines. A large
+gear pump is located in the lowest point of the oil sump,
+and being submerged at all times with oil, does away
+with troublesome stuffing boxes and check valves. The
+oil is first drawn from the strainer in oil sump to the long
+jacket around the intake manifold, then forced to the
+main distributor pipe in crank-case, which leads to all
+main bearings. A bi-pass, located at one end of the
+distributor pipe, can be regulated to provide any pressure
+required, the surplus oil being returned to the case.
+A special feature of this system is the dirt, water and
+sediment trap, located at the bottom of the oil sump.
+This can be removed without disturbing or dismantling
+the oil pump or any oil pipes. A small oil pressure gauge
+is provided, which can be run to the aviator&#8217;s instrument
+board. This registers the oil pressure, and also determines
+its circulation.</p>
+
+<p>The cooling of this motor is accomplished by the oil
+as well as the water, this being covered by patent No.
+1,078,919. This is accomplished by circulating the oil
+around a long intake manifold jacket; the carburetion
+of gasoline cools this regardless of weather conditions.
+Crank-case heat is therefore kept at a minimum. The
+uniform temperature of the cylinders is maintained by
+the use of ingenious internal outlet pipes, running through
+the head of each of the six-cylinders, rubber hose connections
+being used so that any one of the cylinders may
+be removed without disturbing the others. Slots are cut
+in these pipes so that cooler water is drawn directly
+around the exhaust valves. Extra large water jackets
+are provided upon the cylinders, two inches of water
+space is left above the valves and cylinder head. The
+water is circulated by a large centrifugal pump insuring
+ample circulation at all speeds.</p>
+
+<p><span class='pagenum'><a name="Page_542" id="Page_542">[542]</a></span>The crank-shaft is of the five bearing type, being
+machined from a special heat treated drop forging of the
+highest grade nickel steel. The forging is first drilled,
+then roughed out. After this the shaft is straightened,
+turned down to a grinding size, then ground accurately
+to size. The bearing surfaces are of extremely large
+size, over-size, considering general practice in the building
+of high speed engines of similar bore and stroke.
+The crank-shaft bearings are <span class="nowrap">2&#8242;&#8242;</span> in diameter
+by <span class="nowrap">1<sup>15</sup>&#8260;<sub>16</sub>&#8242;&#8242;</span>
+long, excepting the rear main bearing, which is <span class="nowrap">4<sup>3</sup>&#8260;<sub>8</sub>&#8242;&#8242;</span>
+long, and front main bearing, which is <span class="nowrap">2<sup>3</sup>&#8260;<sub>16</sub>&#8242;&#8242;</span> long. Steel
+oil scuppers are pinned and sweated onto the webs of
+the shaft, which allows of properly oiling the connecting
+rod bearings. Two thrust bearings are installed on the
+propeller end of the shaft, one for pull and the other for
+push. The propeller is driven by the crank-shaft flange,
+which is securely held in place upon the shaft by six
+keys. These drive an outside propeller flange, the propeller
+being clamped between them by six through bolts.
+The flange is fitted to a long taper on crank-shaft. This
+enables the propeller to be removed without disturbing
+the bolts. Timing gears and starting ratchets are bolted
+to a flange turned integral with shaft.</p>
+
+<p>The cam-shaft is of the one piece type, air pump
+eccentric, and gear flange being integral. It is made
+from a low carbon specially heat treated nickel forging,
+is first roughed out and drilled entire length; the cams
+are then formed, after which it is case hardened and
+ground to size. The cam-shaft bearings are extra long,
+made from Parson&#8217;s White Brass. A small clutch is
+milled in gear end of shaft to drive revolution indicator.
+The cam-shaft is enclosed in an aluminum housing bolted
+directly on top of all six cylinders, being driven by a
+vertical shaft in connection with bevel gears. This shaft,
+in conjunction with rocker arms, rollers and other working
+parts, are oiled by forcing the oil into end of shaft,
+using same as a distributor, allowing the surplus supply
+to flow back into the crank-case through hollow vertical<span class='pagenum'><a name="Page_543" id="Page_543">[543]</a></span>
+tube. This supply oils the magneto and pump gears.
+Extremely large Tungsten valves, being one-half the cylinder
+diameter, are seated in the cylinder heads. Large
+diameter oil tempered springs held in tool steel cups,
+locked with a key, are provided. The ports are very
+large and short, being designed to allow the gases to enter
+and exhaust with the least possible resistance. These
+valves are operated by overhead one piece cam-shaft in
+connection with short Chrome nickel rocker arms. These
+arms have hardened tool steel rollers on cam end with
+hardened tool steel adjusting screws opposite. This construction
+allows accurate valve timing at all speeds with
+least possible weight.</p>
+
+<p class="center fsize150" style="margin: 4em auto;">CENSORED</p>
+
+<h3>GERMAN AIRPLANE MOTORS</h3>
+
+<p>In a paper on &#8220;Aviation Motors,&#8221; presented by E. H.
+Sherbondy before the Cleveland section of the S. A. E.
+in June, 1917, the Mercedes and Benz airplane motor is
+discussed in some detail and portions of the description
+follow.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig244" id="Fig244"></a>
+<img src="images/illo540.png" alt="Fig. 244" width="600" height="339" />
+<p class="caption">Fig. 244.&mdash;Side and End Sectional Views of Four-Cylinder Argus Engine, a German 100 Horse-Power Design Having
+Bore and Stroke of 140 mm., or 5.60 inches, and Developing Its Power at 1,368 R.P.M. Weight, 350 Pounds.</p></div>
+
+<h3><a name="SecXII_17" id="SecXII_17"></a>MERCEDES MOTOR</h3>
+
+<p>The 150 horse-power six-cylinder Mercedes motor is
+140 millimeters bore and 160 millimeters stroke. The
+Mercedes company started with smaller-sized cylinders,
+namely 100 millimeters bore and 140 millimeters stroke,
+six-cylinders. The principal features of the design are
+forged steel cylinders with forged steel elbows for gas
+passages, pressed steel water jackets, which when welded
+together forms the cylinder assembly, the use of inclined
+overhead valves operated by means of an overhead cam-shaft
+through rocker arms which multiply with the motion
+of the cam. By the use of steel cylinders, not only
+is the weight greatly reduced, but certain freedom from
+distortion through unequal sections, leaks and cracks are
+entirely avoided. The construction is necessarily very
+expensive. It is certainly a sound job. In the details
+of this construction there are a number of important
+things, such as finished gas passages, water-cooled valve
+guides and a very small mass of metal, which is water-cooled,
+surrounding the spark-plug. Of course, it is necessary
+to use very high compression in aviation motors
+in order to secure high power and economy and owing to
+the fact that aviation motors are worked at nearly their
+maximum, the heat flow through the cylinder, piston, and
+valves is many times higher than that encountered in
+automobile motors. It has been found necessary to develop
+special types of pistons to carry the heat from the
+center of the head in order to prevent pre-ignition. In
+the Mercedes motor the pistons have a drop forged steel
+head which includes the piston boss and this head is
+screwed into a cast iron skirt which has been machined
+inside to secure uniform wall thickness.</p>
+
+<p class='pagenum'><a name="Page_544" id="Page_544">[544]</a></p>
+
+<p class="center fsize150" style="margin: 4em auto;">CENSORED</p>
+
+<p class='pagenum' style="margin-top: -1.5em;"><a name="Page_545" id="Page_545"></a></p>
+<p class='pagenum' style="margin-top: -1.5em;"><a name="Page_546" id="Page_546">[546]</a></p>
+
+<table class="nowrap" summary="Table p. 546-547">
+
+<tr class="bb bt2">
+<td class="center padl1 padr1 br">Maker&#8217;s Name<br />and Model</td>
+<td class="center padl1 padr1 br">Num-<br />ber<br />of<br />Cyl.</td>
+<td colspan="2" class="center padl1 padr1 br">Bore<br />(In.)</td>
+<td colspan="2" class="center padl1 padr1 br">Stroke<br />(In.)</td>
+<td colspan="2" class="center padl1 padr1 br">Piston<br />Displace-<br />ment<br />(Cubic<br />In.)</td>
+<td class="center padl1 padr1 br">H.P.</td>
+<td class="center padl1 padr1 br">R.P.M.</td>
+<td class="center padl1 padr1 br">Weight of<br />Engine with<br />Carburetor<br />and Ignition</td>
+<td class="center padl1 padr1">Gas<br />Consump-<br />tion</td>
+</tr>
+
+<tr class="bb">
+<td class="left padr1 br">Aeromarine</td>
+<td class="right padr3 br">6</td>
+<td class="right padr0 padl1">4</td>
+<td class="left padl0 br"><sup>1</sup>&#8260;<sub>2</sub></td>
+<td class="right padr0">5</td>
+<td class="left padl0 br"><sup>1</sup>&#8260;<sub>8</sub></td>
+<td class="right padr0">449</td>
+<td class="br">&nbsp;</td>
+<td class="right padr1 br">85</td>
+<td class="right padr2 br">1400</td>
+<td class="right padr4 br">440</td>
+<td class="center">...</td>
+</tr>
+
+<tr class="bb">
+<td class="left padr1 br">Aeromarine<br />D-12</td>
+<td class="right padr3 br">12</td>
+<td class="right padr0">4</td>
+<td class="left padl0 br"><sup>5</sup>&#8260;<sub>16</sub></td>
+<td class="right padr0">5</td>
+<td class="left padl0 br"><sup>1</sup>&#8260;<sub>8</sub></td>
+<td colspan="2" class="center br">...</td>
+<td class="center br">...</td>
+<td class="center br">...</td>
+<td class="right padr4 br">750</td>
+<td class="center">...</td>
+</tr>
+
+<tr class="bb">
+<td class="left padr1 br">Curtiss OX</td>
+<td class="right padr3 br">8</td>
+<td class="right padr0">4</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">5</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">502</td>
+<td class="left padl0 padr2 br">.6</td>
+<td class="right padr1 br">90</td>
+<td class="right padr2 br">1400</td>
+<td class="right padr4 br">375</td>
+<td class="center">...</td>
+</tr>
+
+<tr class="bb">
+<td class="left padr1 br">Curtiss OXX-2</td>
+<td class="right padr3 br">8</td>
+<td class="right padr0">4</td>
+<td class="left padl0 br"><sup>1</sup>&#8260;<sub>4</sub></td>
+<td class="right padr0">5</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">567</td>
+<td class="left padl0 br">.5</td>
+<td class="right padr1 br">100</td>
+<td class="right padr2 br">1400</td>
+<td class="right padr4 br">423</td>
+<td class="center">...</td>
+</tr>
+
+<tr class="bb">
+<td class="left padr1 br">Curtiss V-2</td>
+<td class="right padr3 br">8</td>
+<td class="right padr0">5</td>
+<td class="left padl0 br">&nbsp;</td>
+<td class="right padr0">7</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">1100</td>
+<td class="br">&nbsp;</td>
+<td class="right padr1 br">200</td>
+<td class="right padr2 br">1400</td>
+<td class="right padr4 br">690</td>
+<td class="center">...</td>
+</tr>
+
+<tr class="bb">
+<td colspan="12" class="center fsize150" style="line-height: 2.5em;"><b>CENSORED</b></td>
+</tr>
+
+<tr class="bb">
+<td class="left padr1 br">General Vehicle<br />Gnome Mono</td>
+<td class="right padr3 br">9</td>
+<td class="right padr0">4</td>
+<td class="left padl0 br">.33</td>
+<td class="right padr0">5</td>
+<td class="left padl0 br">.9</td>
+<td class="right padr0">848</td>
+<td class="br">&nbsp;</td>
+<td class="right padr1 br">100</td>
+<td class="right padr2 br">1200</td>
+<td class="right padr4 br">272</td>
+<td class="left padl1">12 gals/hour<br />at rated H.P.</td>
+</tr>
+
+<tr class="bb">
+<td class="left padr1 br">Gyro K Rotary,<br />Le Rhone Type</td>
+<td class="right padr3 br">7</td>
+<td class="right padr0">4</td>
+<td class="left padl0 br"><sup>1</sup>&#8260;<sub>2</sub></td>
+<td class="right padr0">6</td>
+<td class="br">&nbsp;</td>
+<td colspan="2" class="center br">...</td>
+<td class="right padr1 br">90</td>
+<td class="right padr2 br">1250</td>
+<td class="right padr4 br">215</td>
+<td class="left padl1">8 gals/hour<br />at rated H.P.</td>
+</tr>
+
+<tr class="bb">
+<td class="left padr1 br">Gyro L Rotary,<br />Le Rhone Type</td>
+<td class="right padr3 br">9</td>
+<td class="right padr0">4</td>
+<td class="left padl0 br"><sup>1</sup>&#8260;<sub>2</sub></td>
+<td class="right padr0">6</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">859</td>
+<td class="br">&nbsp;</td>
+<td class="right padr1 br">100</td>
+<td class="right padr2 br">1200</td>
+<td class="right padr4 br">285</td>
+<td class="left padl1">10 gals/hour<br />at rated H.P.</td>
+</tr>
+
+<tr class="bb">
+<td class="left padr1 br">Hall-Scott A-7</td>
+<td class="right padr3 br">4</td>
+<td class="right padr0">5</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">7</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">550</td>
+<td class="br">&nbsp;</td>
+<td class="center br">90-<br />100</td>
+<td class="right padr2 br">1400</td>
+<td class="right padr4 br">410</td>
+<td class="center">...</td>
+</tr>
+
+<tr class="bb">
+<td class="left padr1 br">Hall-Scott A-5</td>
+<td class="right padr3 br">6</td>
+<td class="right padr0">5</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">7</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">825</td>
+<td class="br">&nbsp;</td>
+<td class="right padr1 br">125</td>
+<td class="right padr2 br">1300</td>
+<td class="right padr4 br">592</td>
+<td class="center">...</td>
+</tr>
+
+<tr class="bb">
+<td class="left padr1 br">Hispano-Suiza</td>
+<td class="right padr3 br">8</td>
+<td class="right padr0">4</td>
+<td class="left padl0 br"><sup>5</sup>&#8260;<sub>8</sub></td>
+<td class="right padr0">5</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">672</td>
+<td class="br">&nbsp;</td>
+<td class="right padr1 br">154</td>
+<td class="right padr2 br">1500</td>
+<td class="right padr4 br">455</td>
+<td class="center">...</td>
+</tr>
+
+<tr class="bb">
+<td class="left padr1 br">Knox Motors<br />Co.</td>
+<td class="right padr3 br">12</td>
+<td class="right padr0">4</td>
+<td class="left padl0 br"><sup>3</sup>&#8260;<sub>4</sub></td>
+<td class="right padr0">7</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">1555</td>
+<td class="br">&nbsp;</td>
+<td class="right padr1 br">300</td>
+<td class="right padr2 br">1800</td>
+<td class="right padr4 br">1425</td>
+<td class="left padl1">31.5 gals/hour</td>
+</tr>
+
+<tr class="bb">
+<td class="left padr1 br">Maximotor A-6<span class='pagenum'><a name="Page_547" id="Page_547"></a></span></td>
+<td class="right padr3 br">6</td>
+<td class="right padr0">4</td>
+<td class="left padl0 br"><sup>1</sup>&#8260;<sub>2</sub></td>
+<td class="right padr0">5</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">477</td>
+<td class="br">&nbsp;</td>
+<td class="right padr1 br">85</td>
+<td class="right padr2 br">1600</td>
+<td class="right padr4 br">340</td>
+<td class="center">...</td>
+</tr>
+
+<tr class="bb">
+<td class="left padr1 br">Maximotor B-6</td>
+<td class="right padr3 br">6</td>
+<td class="right padr0">5</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">6</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">706</td>
+<td class="left padl0 br">.8</td>
+<td class="right padr1 br">115</td>
+<td class="right padr2 br">1600</td>
+<td class="right padr4 br">385</td>
+<td class="center">...</td>
+</tr>
+
+<tr class="bb">
+<td class="left padr1 br">Maximotor A-8</td>
+<td class="right padr3 br">8</td>
+<td class="right padr0">4</td>
+<td class="left padl0 br"><sup>1</sup>&#8260;<sub>2</sub></td>
+<td class="right padr0">5</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">636</td>
+<td class="br">&nbsp;</td>
+<td class="right padr1 br">115</td>
+<td class="right padr2 br">1600</td>
+<td class="right padr4 br">420</td>
+<td class="center">...</td>
+</tr>
+
+<tr class="bb">
+<td class="left padr1 br">Packard 12</td>
+<td class="right padr3 br">12</td>
+<td class="right padr0">4</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">6</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">903</td>
+<td class="br">&nbsp;</td>
+<td class="right padr1 br">225</td>
+<td class="right padr2 br">2100</td>
+<td class="right padr4 br">800</td>
+<td class="center">...</td>
+</tr>
+
+<tr class="bb">
+<td class="left padr1 br">Sturtevant 5</td>
+<td class="right padr3 br">8</td>
+<td class="right padr0">4</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">5</td>
+<td class="left padl0 br"><sup>1</sup>&#8260;<sub>2</sub></td>
+<td class="right padr0">552</td>
+<td class="left padl0 br">.9</td>
+<td class="right padr1 br">140</td>
+<td class="right padr2 br">2000</td>
+<td class="right padr4 br">580</td>
+<td class="center">...</td>
+</tr>
+
+<tr class="bb">
+<td class="left padr1 br">Sturtevant 5-A</td>
+<td class="right padr3 br">8</td>
+<td class="right padr0">4</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">5</td>
+<td class="left padl0 br"><sup>1</sup>&#8260;<sub>2</sub></td>
+<td colspan="2" class="center br">...</td>
+<td class="right padr1 br">140</td>
+<td class="right padr2 br">2000</td>
+<td class="right padr4 br">514</td>
+<td class="left padl1">13.75 gals/hour</td>
+</tr>
+
+<tr class="bb">
+<td class="left padr1 br">Thomas 8</td>
+<td class="right padr3 br">8</td>
+<td class="right padr0">4</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">5</td>
+<td class="left padl0 br"><sup>1</sup>&#8260;<sub>2</sub></td>
+<td class="right padr0">552</td>
+<td class="left padl0 br">.9</td>
+<td class="right padr1 br">135</td>
+<td class="right padr2 br">2000</td>
+<td class="center br">630 lbs. with<br />self-starter</td>
+<td class="center">...</td>
+</tr>
+
+<tr class="bb">
+<td class="left padr1 br">Thomas 88</td>
+<td class="right padr3 br">8</td>
+<td class="right padr0">4</td>
+<td class="left padl0 br"><sup>1</sup>&#8260;<sub>8</sub></td>
+<td class="right padr0">5</td>
+<td class="left padl0 br"><sup>1</sup>&#8260;<sub>2</sub></td>
+<td class="right padr0">552</td>
+<td class="left padl0 br">.9</td>
+<td class="right padr1 br">150</td>
+<td class="right padr2 br">2100</td>
+<td class="center br">525 lbs. with<br />self-starter</td>
+<td class="center">...</td>
+</tr>
+
+<tr class="bb">
+<td class="left padr1 br">Wisconsin</td>
+<td class="right padr3 br">6</td>
+<td class="right padr0">5</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">6</td>
+<td class="left padl0 br"><sup>1</sup>&#8260;<sub>2</sub></td>
+<td class="right padr0">765</td>
+<td class="left padl0 br">.7</td>
+<td class="right padr1 br">140</td>
+<td class="right padr2 br">1380</td>
+<td class="right padr4 br">637</td>
+<td class="center">...</td>
+</tr>
+
+<tr class="bb">
+<td class="left padr1 br">Wisconsin</td>
+<td class="right padr3 br">12</td>
+<td class="right padr0">5</td>
+<td class="br">&nbsp;</td>
+<td class="right padr0">6</td>
+<td class="left padl0 br"><sup>1</sup>&#8260;<sub>2</sub></td>
+<td class="right padr0">1531</td>
+<td class="left padl0 br">.4</td>
+<td class="right padr1 br">250</td>
+<td class="right padr2 br">1200</td>
+<td class="center br">...</td>
+<td class="center">...</td>
+</tr>
+
+</table>
+
+<p><span class='pagenum'><a name="Page_548" id="Page_548">[548]</a></span>The carburetor used on this 150 horse-power Mercedes
+motor is precisely of the same type used on the
+Twin Six motor. It has two venturi throats, in the center
+of which is placed the gasoline spray nozzle of conventional
+type, fixed size orifices, immediately above which
+are placed two panel type throttles with side outlets.
+An idling or primary nozzle is arranged to discharge
+above the top of the venturi throat. The carburetor
+body is of cast aluminum and is water jacketed. It is
+bolted directly to air passage passing through the top
+and bottom half of the crank-case which passes down
+through the oil reservoir. The air before reaching the
+carburetor proper to some extent has cooled the oil in
+the crank chamber and has itself been heated to assist<span class='pagenum'><a name="Page_549" id="Page_549">[549]</a></span>
+in the vaporization. The inlet pipes themselves are copper.
+All the passages between the venturi throat and
+the inlet valve have been carefully finished and polished.
+The only abnormal thing in the design of this motor is
+the short connecting rod which is considerably less than
+twice the stroke and would be considered very bad practice
+in motor car engines. A short connecting rod, however,
+possesses two very real virtues in that it cuts down height
+of the motor and the piston passes over the bottom dead
+center much more slowly than with a long rod.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig245" id="Fig245"></a>
+<img src="images/illo544.png" alt="Fig. 245" width="500" height="387" />
+<p class="caption">Fig. 245.&mdash;Part Sectional View of 90 Horse-Power Mercedes Engine,
+Which is Typical of the Design of Larger Sizes.</p></div>
+
+<p>Other features of the design are a very stiff crank-case,
+both halves of which are bolted together by means
+of long through bolts, the crank-shaft main bearings are
+seated in the lower half of the case instead of in the
+usual caps and no provision is made for taking up the
+main bearings. The Mercedes company uses a plunger<span class='pagenum'><a name="Page_550" id="Page_550">[550]</a></span>
+type of pump having mechanically operated piston valves
+and it is driven by means of worm gearing.</p>
+
+<p>The overhead cam-shaft construction is extremely
+light. The cam-shaft is mounted in a nearly cylindrical
+cast bronze case and is driven by means of bevel gears
+from the crank-shaft. The vertical bevel gear shaft
+through which the drive is taken from the crank-shaft to
+the cam-shaft operates at one and one-half times the
+crank-shaft speeds and the reduction to the half-time
+cam-shaft is secured through a pair of bevels. On this
+vertical shaft there is mounted the water pump and a
+bevel gear for driving two magnetos. The water pump
+mounted on this shaft tends to steady the drive and avoid
+vibration in the gearing.</p>
+
+<p>The cylinder sizes of six-cylinder aviation motors
+which have been built by Mercedes are</p>
+
+<table summary="table p 550">
+
+<tr>
+<td class="center" style="width: 10em;">Bore</td>
+<td class="center" style="width: 10em;">Stroke</td>
+<td class="center" style="width: 10em;">Horse-power</td>
+</tr>
+
+<tr>
+<td class="center">105 mm.</td>
+<td class="center">140 mm.</td>
+<td class="center">100</td>
+</tr>
+
+<tr>
+<td class="center">120 mm.</td>
+<td class="center">140 mm.</td>
+<td class="center">135</td>
+</tr>
+
+<tr>
+<td class="center">140 mm.</td>
+<td class="center">150 mm.</td>
+<td class="center">150</td>
+</tr>
+
+<tr>
+<td class="center">140 mm.</td>
+<td class="center">160 mm.</td>
+<td class="center">160</td>
+</tr>
+
+</table>
+
+<p>The largest of these motors has recently had its horsepower
+increased to 176 at 1450 R.&nbsp;P.&nbsp;M. This general
+design of motor has been the foundation for a great many
+other aviation motor designs, some of which have proved
+very successful but none of which is equal to the original.
+Among the motors which follow more or less closely
+the scheme of design and arrangement are the Hall-Scott,
+the Wisconsin motor, the Renault water-cooled, the Packard,
+the Christofferson and the Rolls-Royce. Each of
+these motors show considerable variation in detail. The
+Rolls-Royce and Renault are the only ones who have used
+the steel cylinder with the steel jacket. The Wisconsin
+motor uses an aluminum cylinder with a hardened steel
+liner and cast-iron valve seats. The Christofferson has
+somewhat similar design to the Wisconsin with the exception
+that the valve seats are threaded into the aluminum<span class='pagenum'><a name="Page_551" id="Page_551">[551]</a></span>
+jacket and the cylinder head has a blank end which
+is secured to the aluminum casting by means of the valve
+seat pieces. The Rolls-Royce motors show small differences
+in details of design in cylinder head and cam-shaft
+housing from the Mercedes on which it has taken out
+patents, not only abroad but in this country.</p>
+
+<h3><a name="SecXII_18" id="SecXII_18"></a>THE BENZ MOTOR</h3>
+
+<p>In the Kaiser prize contest for aviation motors a four-cylinder
+Benz motor of 130 by 180 mm. won first prize,
+developing 103 B.&nbsp;H.&nbsp;P. at 1290 R.&nbsp;P.&nbsp;M. The fuel consumption
+was 210 grams per horse-power hour. Total
+weight of the motor was 153 kilograms. The oil consumption
+was .02 of a kilogram per horse-power hour.
+This motor was afterward expanded into a six-cylinder
+design and three different sizes were built.</p>
+
+<p>The accompanying table gives some of the details of
+weight, horse-power, etc.</p>
+
+<table class="fsize80" summary="Table p. 551">
+
+<tr>
+<td class="left top padr5">Motor type</td>
+<td colspan="2" class="center padr4">B</td>
+<td colspan="2" class="center padr4">FD</td>
+<td colspan="2" class="center padr4">FF</td>
+</tr>
+
+<tr>
+<td class="left top padr5">Rated horse-power</td>
+<td class="right bot padr0">85</td>
+<td class="padr4">&nbsp;</td>
+<td class="right bot padr0">100</td>
+<td class="padr4">&nbsp;</td>
+<td class="right bot padr0">150</td>
+<td class="padr4">&nbsp;</td>
+</tr>
+
+<tr>
+<td class="left top padr5">Horse-power at 1250 r.p.m</td>
+<td class="right bot padr0">88</td>
+<td>&nbsp;</td>
+<td class="right bot padr0">108</td>
+<td>&nbsp;</td>
+<td class="right bot padr0">150</td>
+<td>&nbsp;</td>
+</tr>
+
+<tr>
+<td class="left top padr5">Horse-power at 1350 r.p.m</td>
+<td class="right bot padr0">95</td>
+<td>&nbsp;</td>
+<td class="right bot padr0">115</td>
+<td>&nbsp;</td>
+<td class="right bot padr0">160</td>
+<td>&nbsp;</td>
+</tr>
+
+<tr>
+<td class="left top padr5">Bore in millimeters</td>
+<td class="right bot padr0">106</td>
+<td>&nbsp;</td>
+<td class="right bot padr0">116</td>
+<td>&nbsp;</td>
+<td class="right bot padr0">130</td>
+<td>&nbsp;</td>
+</tr>
+
+<tr>
+<td class="left top padr5">Stroke in millimeters</td>
+<td class="right bot padr0">150</td>
+<td>&nbsp;</td>
+<td class="right bot padr0">160</td>
+<td>&nbsp;</td>
+<td class="right bot padr0">180</td>
+<td>&nbsp;</td>
+</tr>
+
+<tr>
+<td class="left top padr5">Offset of the cylinders in millimeters</td>
+<td class="right bot padr0">18</td>
+<td>&nbsp;</td>
+<td class="right bot padr0">20</td>
+<td>&nbsp;</td>
+<td class="right bot padr0">20</td>
+<td>&nbsp;</td>
+</tr>
+
+<tr>
+<td class="left top padr5">Rate of gasoline consumption in grams</td>
+<td class="right bot padr0">240</td>
+<td>&nbsp;</td>
+<td class="right bot padr0">230</td>
+<td>&nbsp;</td>
+<td class="right bot padr0">225</td>
+<td>&nbsp;</td>
+</tr>
+
+<tr>
+<td class="left top padr5">Oil consumption in grams per b.h.p. hour</td>
+<td class="right bot padr0">10</td>
+<td>&nbsp;</td>
+<td class="right bot padr0">10</td>
+<td>&nbsp;</td>
+<td class="right bot padr0">10</td>
+<td>&nbsp;</td>
+</tr>
+
+<tr>
+<td class="left top padr5">Oil capacity in kilograms</td>
+<td class="right bot padr0">36</td>
+<td>&nbsp;</td>
+<td class="right bot padr0">4</td>
+<td>&nbsp;</td>
+<td class="right bot padr0">4</td>
+<td class="left bot padl0"><sup>1</sup>&#8260;<sub>2</sub></td>
+</tr>
+
+<tr>
+<td class="left top padr5">Water capacity in litres</td>
+<td class="right bot padr0">5</td>
+<td class="left bot padl0"><sup>1</sup>&#8260;<sub>2</sub></td>
+<td class="right bot padr0">7</td>
+<td class="left bot padl0"><sup>1</sup>&#8260;<sub>2</sub></td>
+<td class="right bot padr0">9</td>
+<td class="left bot padl0"><sup>1</sup>&#8260;<sub>2</sub></td>
+</tr>
+
+<tr>
+<td class="left top padr5">The weight with water and oil but with two magnetos, fuel feeder and air pump in kilograms</td>
+<td class="right bot padr0">170</td>
+<td>&nbsp;</td>
+<td class="right bot padr0">200</td>
+<td>&nbsp;</td>
+<td class="right bot padr0">245</td>
+<td>&nbsp;</td>
+</tr>
+
+<tr>
+<td class="left top padr5">The weight of motors, including the water pump, two magnetos, double ignition, etc.</td>
+<td class="right bot padr0">160</td>
+<td>&nbsp;</td>
+<td class="right bot padr0">190</td>
+<td>&nbsp;</td>
+<td class="right bot padr0">230</td>
+<td>&nbsp;</td>
+</tr>
+
+<tr>
+<td class="left top padr5">The weight of the exhaust pipe, complete in kilograms</td>
+<td class="right bot padr0">4</td>
+<td>&nbsp;</td>
+<td class="right bot padr0">4</td>
+<td class="left bot padl0">.8</td>
+<td class="right bot padr0">5</td>
+<td class="left bot padl0"><sup>1</sup>&#8260;<sub>2</sub></td>
+</tr>
+
+<tr>
+<td class="left top padr5">The weight of the propeller hub in kilograms.</td>
+<td class="right bot padr0">3</td>
+<td class="left bot padl0"><sup>1</sup>&#8260;<sub>2</sub></td>
+<td class="right bot padr0">4</td>
+<td>&nbsp;</td>
+<td class="right bot padr0">4</td>
+<td>&nbsp;</td>
+</tr>
+
+</table>
+
+<p>The Benz cylinder is a simple, straightforward design
+and a very reliable construction and not particularly difficult
+to manufacture. The cylinder is cast of iron without<span class='pagenum'><a name="Page_552" id="Page_552">[552]</a></span>
+a water jacket but including 45 degrees angle elbows to
+the valve ports. The cylinders are machined wherever
+possible and at other points have been hand filed and
+scraped, after which a jacket, which is pressed in two
+halves, is gas welded by means of short pipes welded on
+to the jacket. The bottom and the top of the cylinders
+become water galleries, and by this means separate water
+pipes with their attendant weight and complication are
+eliminated. Rubber rings held in aluminum clamps serve
+to connect the cylinders together. The whole construction
+turns out very neat and light. The cylinder walls
+are 4 mm. or <span class="nowrap"><sup>3</sup>&#8260;<sub>16</sub>&#8242;&#8242;</span> thick and the combustion chamber is of
+cylindrical pancake form and is 140 mm. or 5.60 inch in
+diameter. The valve seats are 68 mm. in diameter and
+the valve port is 62 mm. in diameter.</p>
+
+<p>The passage joining the port is 57 mm. in diameter.
+In order to insert the valves into the cylinder the valve
+stem is made with two diameters and the valve has to
+be cocked to insert it in the guide, which has a bronze
+bushing at its upper end to compensate for the smaller
+valve stem diameter. The valve stem is 14 mm. or <span class="nowrap"><sup>9</sup>&#8260;<sub>16</sub>&#8242;&#8242;</span>
+in diameter and is reduced at its upper portion to 9<sup>1</sup>&#8260;<sub>2</sub> mm.
+The valves are operated through a push rod and rocker
+arm construction, which is <span class="nowrap"><sup>7</sup>&#8260;<sub>16</sub>&#8242;&#8242;</span> and exceedingly light.
+Rocker arm supports are steel studs with enlarged heads
+to take a double row ball bearing. A roller is mounted
+at one end of the rocker arm to impinge on the end of
+the valve stem, and the rocker arm has an adjustable
+globe stud at the other end. The push rods are light steel
+tubes with a wall thickness of 0.75 mm. and have a hardened
+steel cup at their upper end to engage the rocker
+arm globe stud and a hardened steel globe at their lower
+end to socket in the roller plunger.</p>
+
+<p>The Benz cam-shaft has a diameter of 26 mm. and is
+bored straight through 18 mm. and there is a spiral gear
+made integrally with the shaft in about the center of its
+length for driving the oil pump gear. The cam faces are
+10 mm. wide. There is also, in addition to the intake<span class='pagenum'><a name="Page_553" id="Page_553">[553]</a></span>
+and exhaust cams, a set of half compression cams. The
+shaft is moved longitudinally in its bearings by means of
+an eccentric to put these cams into action. At the fore
+end of the shaft is a driving gear flange which is very
+small in diameter and very thin. The flange is 68 mm.
+in diameter and 4 mm. thick and is tapped to take 6 mm.
+bolts. The total length of cam-shaft is 1038 mm., and it
+becomes a regular gun boring job to drill a hole of this
+length.</p>
+
+<p>The cam-shaft gear is 140 mm. or 5<sup>1</sup>&#8260;<sub>2</sub> inches outside
+diameter. It has fifty-four teeth and the gear face is 15
+mm. or <span class="nowrap"><sup>19</sup>&#8260;<sub>32</sub>&#8242;&#8242;.</span> The flange and web have an average thickness
+of 4 mm. or <span class="nowrap"><sup>5</sup>&#8260;<sub>32</sub>&#8242;&#8242;</span> and the web is drilled full of holes
+interposed between the spur gear mounted on the cam-shaft
+and the cam-shaft gear. There is a gear which
+serves to drive the magnetos and tachometer, also the
+air pump. The shaft is made integrally with this gear
+and has an eccentric portion against which the air pump
+roll plunger impinges.</p>
+
+<p>The seven-bearing crank-shaft is finished all over in
+a beautiful manner, and the shaft out of the particular
+motor we have shows no signs of wear whatever. The
+crank-pins are 55 mm. in diameter and 69 mm. long.
+Through both the crank-pin and main bearings there is
+drilled a 28 mm. hole, and the crank cheeks are plugged
+with solder. The crank cheeks are also built to convey
+the lubricant to the crank-pins. At the fore end of the
+crank cheek there is pressed on a spur driving gear.
+There is screwed on to the front end of the shaft a piece
+which forms a bevel water pump driving gear and the
+starting dog. At the rear end of the shaft very close to
+the propeller hub mounting there is a double thrust bearing
+to take the propeller thrust.</p>
+
+<p>Long, shouldered studs are screwed into the top half
+of the crank-case portion of the case and pass clean
+through the bottom half of the case. The case is very
+stiff and well ribbed. The three center bearing diaphragms
+have double walls. The center one serves as a<span class='pagenum'><a name="Page_554" id="Page_554">[554]</a></span>
+duct through which water pipe passes, and those on either
+side of the center form the carburetor intake air passages
+and are enlarged in section at one side to take the carburetor
+barrel throttle.</p>
+
+<p>The pistons are of cast iron and carry three concentric
+rings <sup>1</sup>&#8260;<sub>4</sub> inch wide on their upper end, which are pinned
+at the joint. The top of the piston forms the frustum
+of the cone and the pistons are 110 mm. in length. The
+lower portion of the skirt is machined inside and has a
+wall thickness of 1 mm. Riveted to the piston head is
+a conical diaphragm which contacts with the piston pin
+when in place and serves to carry the heat off the center
+of the piston.</p>
+
+<p>The oil pump assembly comprises a pair of plunger
+pumps which draw oil from a separate outside pump, and
+constructed integrally with it is a gear pump which delivers
+the oil under about 60 pound pressure through a
+set of copper pipes in the base to the main bearings. The
+plunger oil pump shows great refinement of detail. A
+worm wheel and two eccentrics are machined up out of
+one piece and serve to operate the plungers.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig246" id="Fig246"></a>
+<img src="images/illo550.png" alt="Fig. 246" width="600" height="336" />
+<p class="caption">Fig. 246.&mdash;Part Sectional Side View and Sectional End View of Benz 160 Horse-Power Aviation Engine.</p></div>
+
+<p>Some interesting details of the 160 horse-power Benz
+motor, which is shown at <a href="#Fig246">Fig. 246</a>, are reproduced from
+the &#8220;Aerial Age Weekly,&#8221; and show how carefully the
+design has been considered.</p>
+
+<ul class="barelist">
+<li>Maximum horse-power, 167.5 B.&nbsp;H.&nbsp;P.</li>
+<li>Speed at maximum horse-power, 1,500 R.&nbsp;P.&nbsp;M.</li>
+<li>Piston speed at maximum horse-power, 1,770 ft. per minute.</li>
+<li>Normal horse-power, 160 B.&nbsp;H.&nbsp;P.</li>
+<li>Speed at normal horse-power, 1,400 R.&nbsp;P.&nbsp;M.</li>
+<li>Piston speed at normal horse-power, 1,656 ft. per minute.</li>
+<li>Brake mean pressure at maximum horse-power, 101.2 pound per square inch.</li>
+<li><span class='pagenum'><a name="Page_556" id="Page_556">[556]</a></span><span class='pagenum'><a name="Page_555" id="Page_555">[555]</a></span>Brake mean pressure at normal horse-power, 103.4 pound per square inch.</li>
+<li>Specific power cubic inch swept volume per B.&nbsp;H.&nbsp;P.,
+5.46 cubic inch; 160 B.&nbsp;H.&nbsp;P.</li>
+<li>Weight of piston, complete with gudgeon pin, rings,
+etc., 5.0 pound.</li>
+<li>Weight of connecting rod, complete with bearings,
+4.99 pound; 1.8 pound reciprocating.</li>
+<li>Weight of reciprocating parts per cylinder, 6.8 pound.</li>
+<li>Weight of reciprocating parts per square inch of
+piston area, 0.33 pound.</li>
+<li>Outside diameter of inlet valve, 68 mm.; 2.68 inches.</li>
+<li>Diameter of inlet valve port (<i>d</i>), 61.5 mm.; 2.42 inches.</li>
+<li>Maximum lift of inlet valve (<i>h</i>), 11 mm.; 0.443 inch.</li>
+<li>Area of inlet valve opening (&#960; <i>d</i> <i>h</i>), 21.25 square cm.;
+3.29 square inches.</li>
+<li>Inlet valve opens, degrees on crank, top dead center.</li>
+<li>Inlet valve closes, degrees on crank, <span class="nowrap">60&deg;</span> late; 35 mm.
+late.</li>
+<li>Outside diameter of exhaust valve, 68 mm.; 2.68 inches.</li>
+<li>Diameter of exhaust valve port (<i>d</i>), 61.5 mm.; 2.42
+inches.</li>
+<li>Maximum lift of exhaust valve (<i>h</i>) 11 mm.; 0.433
+inch.</li>
+<li>Area of exhaust valve opening (&#960; <i>d</i> <i>h</i>), 21.25 square
+cm.; 3.29 square inches.</li>
+<li>Exhaust valve opens, degrees on crank, <span class="nowrap">60&deg;</span> early;
+35 mm. early.</li>
+<li>Exhaust valve closes, degrees on crank, <span class="nowrap">16<sup>1</sup>&#8260;<sub>2</sub>&deg;</span> late;
+5 mm. late.</li>
+<li>Length of connecting rod between centers, 314 mm.;
+12.36 inches.</li>
+<li>Ratio connecting rod to crank throw, 3.49:1.</li>
+<li>Diameter of crank-shaft, 55 mm. outside, 2.165 inches;
+28 mm. inside, 1.102 inches.</li>
+<li>Diameter of crank-pin, 55 mm. outside, 2.165 inches;
+28 mm. inside, 1.102 inches.</li>
+<li>Diameter of gudgeon pin, 30 mm. outside, 1.181 inches;
+<span class='pagenum'><a name="Page_557" id="Page_557">[557]</a></span>19 mm. inside, 0.708 inch.</li>
+<li>Diameter of cam-shaft, 26 mm. outside, 1.023 inches;
+18 mm. inside, 0.708 inch.</li>
+<li>Number of crank-shaft bearings, 7.</li>
+<li>Projected area of crank-pin bearings, 36.85 square
+cm.; 5.72 square inches.</li>
+<li>Projected area of gudgeon pin bearings, 22.20 square
+cm.; 3.44 square inches.</li>
+<li>Firing sequence, 1, 5, 3, 6, 2, 4.</li>
+<li>Type of magnetos, ZH6 Bosch.</li>
+<li>Direction of rotation of magneto from driving end,
+one clock, one anti-clock.</li>
+<li>Magneto timing, full advance, <span class="nowrap">30&deg;</span> early (16 mm.
+early).</li>
+<li>Type of carburetors (2) Benz design.</li>
+<li>Fuel consumption per hour, normal horse-power, 0.57
+pint.</li>
+<li>Normal speed of propeller, engine speed, 1,400 R.&nbsp;P.&nbsp;M.</li>
+</ul>
+
+<h3><a name="SecXII_19" id="SecXII_19"></a>AUSTRO-DAIMLER ENGINE</h3>
+
+<p>One of the first very successful European flying engines
+which was developed in Europe is the Austro-Daimler,
+which is shown in <a href="#Fig090">end section</a> in a preceding chapter. The
+first of these motors had four-cylinders, 120 by 140 millimeters,
+bore and stroke, with cast iron cylinders, overhead
+valves operated by means of a single rocker arm,
+controlled by two cams and the valves were closed by a
+single leaf spring which oscillates with the rocker arm.
+The cylinders are cast singly and have either copper or
+steel jackets applied to them. The four-cylinder design
+was afterwards expanded to the six-cylinder design and
+still later a six-cylinder motor of 130 by 175 millimeters
+was developed. This motor uses an offset crank-shaft,
+as does the Benz motor, and the effect of offset has been
+discussed earlier on in this treatise. The Benz motor also
+uses an offset cam-shaft which improves the valve operation
+and changes the valve lift diagram. The lubrication
+also is different than any other aviation motor, since<span class='pagenum'><a name="Page_558" id="Page_558">[558]</a></span>
+individual high pressure metering pumps are used to
+deliver fresh oil only to the bearings and cylinders, as
+was the custom in automobile practice some ten years ago.</p>
+
+<h3><a name="SecXII_20" id="SecXII_20"></a>SUNBEAM AVIATION ENGINES</h3>
+
+<p>These very successful engines have been developed by
+Louis Coatalen. At the opening of the war the largest
+sized Coatalen motor was 225 horse-power and was of the
+L-head type having a single cam-shaft for operating
+valves and was an evolution from the twelve-cylinder
+racing car which the Sunbeam Company had previously
+built. Since 1914 the Sunbeam Company have produced
+engines of six-, eight-, twelve- and eighteen-cylinders from
+150 to 500 horse-power with both iron and aluminum
+cylinders. For the last two years all the motors have had
+overhead cam-shafts with a separate shaft for operating
+the intake and exhaust valves. Cam-shafts are connected
+through to the crank-shaft by means of a train of spur
+gears, all of which are mounted on two double row ball
+bearings. In the twin six, 350 horse-power engine, operating
+at 2100 R.&nbsp;P.&nbsp;M., requires about 4 horse-power
+to operate the cam-shafts. This motor gives 362 horsepower
+at 2100 revolutions and has a fuel consumption of
+<sup>51</sup>&#8260;<sub>100</sub> of a pint per brake horse-power hour. The cylinders
+are 110 by 160 millimeters. The same design has been
+expanded into an eighteen-cylinder which gives 525 horsepower
+at 2100 turns. There has also been developed a
+very successful eight-cylinder motor rated at 2220 horsepower
+which has a bore and stroke of 120 by 130 millimeters,
+weight 450 pounds. This motor is an aluminum
+block construction with steel sleeves inserted. Three
+valves are operated, one for the inlet and two for the
+exhaust. One cam-shaft operates the three valves.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig247" id="Fig247"></a>
+<img src="images/illo554.jpg" alt="Fig. 247" width="450" height="509" />
+<p class="caption">Fig. 247.&mdash;At Top, the Sunbeam Overhead Valve 170 Horse-Power Six-Cylinder
+Engine. Below, Side View of Sunbeam 350 Horse-Power
+Twelve-Cylinder Vee Engine.</p></div>
+
+<p>The modern Sunbeam engines operate with a mean
+effective pressure of 135 pounds with a compression ratio
+of 6 to 1 sea level. The connecting rods are of the articulated
+type as in the Renault motor and are very short.<span class='pagenum'><a name="Page_559" id="Page_559">[559]</a></span>
+The weight of these motors turns out at 2.6 pounds per
+brake horse-power, and they are able to go through a
+100 hour test without any trouble of any kind. The lubricating
+system comprises a dry base and oil pump for
+drawing the oil off from the base, whence it is delivered
+to the filter and cooling system. It then is pumped by a
+separate high pressure gear pump through the entire
+motor. In these larger European motors, castor-oil is<span class='pagenum'><a name="Page_561"
+id="Page_561">[561]</a></span><span class='pagenum'><a name="Page_560" id="Page_560"></a></span>
+used largely for lubrication. It is said that without the
+use of castor-oil it is impossible to hold full power for
+five hours. Coatalen favors aluminum cylinders rather
+than cast iron. The series of views in <a href="#Fig247">Figs. 247</a> to <a href="#Fig250">250</a>
+inclusive, illustrates the vertical, narrow type of engine;
+the V-form; and the broad arrow type wherein three
+rows, each of six-cylinders, are set on a common crank-case.
+In this water-cooled series the gasoline and oil
+consumption are notably low, as is the weight per horse-power.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig248" id="Fig248"></a>
+<img src="images/illo555.jpg" alt="Fig. 248" width="600" height="350" />
+<p class="caption">Fig. 248.&mdash;Side View of Eighteen-Cylinder Sunbeam Coatalen Aircraft Engine Rated at 475 B.H.P.</p></div>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig249" id="Fig249"></a>
+<img src="images/illo556.jpg" alt="Fig. 249" width="450" height="410" />
+<p class="caption">Fig. 249.&mdash;Sunbeam Eighteen-Cylinder Motor, Viewed from Pump and
+Magneto End.</p></div>
+
+<p>In the eighteen-cylinder overhead valve Sunbeam-Coatalen
+aircraft engine of 475 brake horse-power, there
+are no fewer than half a dozen magnetos. Each magneto
+is inclosed. Two sparks are furnished to each cylinder<span class='pagenum'><a name="Page_562" id="Page_562">[562]</a></span>
+from independent magnetos. On this engine there are
+also no fewer than six carburetors. Shortness of crank-shaft,
+and therefore of engine length, and absence of
+vibration are achieved by the linking of the connecting-rods.
+Those concerned with three-cylinders in the broad
+arrow formation work on one crank-pin, the outer rods
+being linked to the central master one. In consequence
+of this arrangement, the piston travel in the case of the
+central row of cylinders is 160 mm., while the stroke of
+the pistons of the cylinders set on either side is in each
+case 168 mm. Inasmuch as each set of six-cylinders is
+completely balanced in itself, this difference in stroke
+does not affect the balance of the engine as a whole. The<span class='pagenum'><a name="Page_563" id="Page_563">[563]</a></span>
+duplicate ignition scheme also applies to the twelve-cylinder
+350 brake horse-power Sunbeam-Coatalen overhead
+valve aircraft engine type. It is distinguishable,
+incidentally, by the passage formed through the center of
+each induction pipe for the sparking plug in the center
+cylinder of each block of three. In this, as in the eighteen-cylinder
+and the six-cylinder types, there are two cam-shafts
+for each set of cylinders. These cam-shafts are
+lubricated by low pressure and are operated through a
+train of inclosed spur wheels at the magneto end of the
+machine. The six-cylinder, 170 brake horse-power vertical
+type employs the same general principles, including the
+detail that each carburetor serves gas to a group of three-cylinders
+only. It will be observed that this engine presents
+notably little head resistance, being suitable for
+multi-engined aircraft.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig250" id="Fig250"></a>
+<img src="images/illo557.jpg" alt="Fig. 250" width="450" height="423" />
+<p class="caption">Fig. 250.&mdash;Propeller End of Sunbeam Eighteen-Cylinder 475 B.H.P.
+Aviation Engine.</p></div>
+
+<h3><a name="SecXII_21" id="SecXII_21"></a>INDICATING METERS FOR AUXILIARY SYSTEMS</h3>
+
+<p class='pagenum' style="margin-top: -1.5em;"><a name="Page_564" id="Page_564">[564]</a></p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig251" id="Fig251"></a>
+<img src="images/illo559.png" alt="Fig. 251" width="600" height="402" />
+<p class="caption">Fig. 251.&mdash;View of Airplane Cowl Board, Showing the Various Navigating and Indicating Instruments to Aid the
+Aviator in Flight.</p></div>
+
+<p>The proper functioning of the power plant and the
+various groups comprising it may be readily ascertained
+at any time by the pilot because various indicating meters
+and pressure gauges are provided which are located on a
+dash or cowl board in front of the aviator, as shown at
+<a href="#Fig251">Fig. 251</a>. The speed indicator corresponds to the speedometer
+of an automobile and gives an indication of the speed
+the airplane is making, which taken in conjunction with the
+clock will make it possible to determine the distance covered
+at a flight. The altimeter, which is an aneroid
+barometer, outlines with fair accuracy the height above
+the ground at which a plane is flying. These instruments
+are furnished to enable the aviator to navigate the airplane
+when in the air, and if the machine is to be used
+for cross-country flying, they may be supplemented by a
+compass and a drift set. It will be evident that these
+are purely navigating instruments and only indicate the
+motor condition in an indirect manner. The best way of
+keeping track of the motor action is to watch the tachometer<span class='pagenum'><a name="Page_565" id="Page_565">[565]</a></span>
+or revolution counter which is driven from the
+engine by a flexible shaft. This indicates directly the
+number of revolutions the engine is making per minute
+and, of course, any slowing up of the engine in normal
+flights indicates that something is not functioning as it
+should. The tachometer operates on the same principle
+as the speed indicating device or speedometer used in
+automobiles except that the dial is calibrated to show
+revolutions per minute instead of miles per hour. At the
+extreme right of the dash at <a href="#Fig251">Fig. 251</a> the spark advance
+and throttle control levers are placed. These, of course,
+regulate the motor speed just as they do in an automobile.
+Next to the engine speed regulating levers is placed a
+push button cut-out switch to cut out the ignition and
+stop the motor. Three pressure gauges are placed in a
+line. The one at the extreme right indicates the pressure
+of air on the fuel when a pressure feed system is used.
+The middle one shows oil pressure, while that nearest
+the center of the dash board is employed to show the air
+pressure available in the air starting system. It will be
+evident that the character of the indicating instruments
+will vary with the design of the airplane. If it was provided
+with an electrical starter instead of an air system
+electrical indicating instruments would have to be provided.</p>
+
+<h3><a name="SecXII_22" id="SecXII_22"></a>COMPRESSED AIR-STARTING SYSTEMS</h3>
+
+<p>Two forms of air-starting systems are in general use,
+one in which the crank-shaft is turned by means of an
+air motor, the other class where compressed air is admitted
+to the cylinders proper and the motor turned over
+because of the air pressure acting on the engine pistons.
+A system known as the &#8220;Never-Miss&#8221; utilizes a small
+double-cylinder air pump is driven from the engine by
+means of suitable gearing and supplies air to a substantial
+container located at some convenient point in the
+fuselage. The air is piped from the container to a dash-control
+valve and from this member to a peculiar form<span class='pagenum'><a name="Page_566" id="Page_566">[566]</a></span>
+of air motor mounted near the crank-shaft. The air
+motor consists of a piston to which a rack is fastened
+which engages a gear mounted on the crank shaft provided
+with some form of ratchet clutch to permit it to
+revolve only in one direction, and then only when the
+gear is turning faster than the engine crank-shaft.</p>
+
+<p>The method of operation is extremely simple, the
+dash-control valve admitting air from the supply tank
+to the top of the pump cylinder. When in the position
+shown in cut the air pressure will force the piston and
+rack down and set the engine in motion. A variety of
+air motors are used and in some the pump and motor may
+be the same device, means being provided to change the
+pump to an air motor when the engine is to be turned over.</p>
+
+<p>The &#8220;Christensen&#8221; air starting system is shown at
+<a href="#Fig252">Figs. 252</a> and <a href="#Fig253">253</a>. An air pump is driven by the engine,
+and this supplies air to an air reservoir or container
+attached to the fuselage. This container communicates
+with the top of an air distributor when a suitable control
+valve is open. An air pressure gauge is provided to
+enable one to ascertain the air pressure available. The
+top of each cylinder is provided with a check valve,
+through which air can flow only in one direction, i.e., from
+the tank to the interior of the cylinder. Under explosive
+pressure these check valves close. The function of the
+distributor is practically the same as that of an ignition
+timer, its purpose being to distribute the air to the cylinders
+of the engine only in the proper firing order. All
+the while that the engine is running and the car is in
+motion the air pump is functioning, unless thrown out of
+action by an easily manipulated automatic control. When
+it is desired to start the engine a starting valve is opened
+which permits the air to flow to the top of the distributor,
+and then through a pipe to the check valve on top of the
+cylinder about to explode. As the air is going through
+under considerable pressure it will move the piston down
+just as the explosion would, and start the engine rotating.
+The inside of the distributor rotates and directs a charge<span class='pagenum'><a name="Page_567" id="Page_567">[567]</a></span>
+of air to the cylinder next to fire. In this way the engine
+is given a number of revolutions, and finally a charge of
+gas will be ignited and the engine start off on its cycle of
+operation. To make starting positive and easier some
+gasoline is injected in with the air so an inflammable mixture
+is present in the cylinders instead of air only. This
+ignites easily and the engine starts off sooner than would
+otherwise be the case. The air pressure required varies
+from 125 to 250 pounds per square inch, depending upon
+the size and type of the engine to be set in motion.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig252" id="Fig252"></a>
+<img src="images/illo562.jpg" alt="Fig. 252" width="450" height="488" />
+<p class="caption">Fig. 252.&mdash;Parts of Christensen Air Starting System Shown at A, and
+Application of Piping and Check Valves to Cylinders of Thomas-Morse
+Aeromotor Outlined at B.</p></div>
+
+<p class='pagenum' style="margin-top: -1.5em;"><a name="Page_568" id="Page_568">[568]</a></p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig253" id="Fig253"></a>
+<img src="images/illo563.png" alt="Fig. 253" width="600" height="371" />
+<p class="caption">Fig. 253.&mdash;Diagrams Showing Installation of Air Starting System on Thomas-Morse Aviation Motor.</p></div>
+
+<p class='pagenum'><a name="Page_569" id="Page_569">[569]</a></p>
+
+<h3><a name="SecXII_23" id="SecXII_23"></a>ELECTRIC STARTING SYSTEMS</h3>
+
+<p>Starters utilizing electric motors to turn over the
+engine have been recently developed, and when properly
+made and maintained in an efficient condition they answer
+all the requirements of an ideal starting device.
+The capacity is very high, as the motor may draw current
+from a storage battery and keep the engine turning
+over for considerable time on a charge. The objection
+against their use is that it requires considerable complicated
+and costly apparatus which is difficult to understand
+and which requires the services of an expert electrician
+to repair should it get out of order, though if battery
+ignition is used the generator takes the place of the
+usual ignition magneto.</p>
+
+<p>In the Delco system the electric current is generated
+by a combined motor-generator permanently geared to
+the engine. When the motor is running it turns the
+armature and the motor generator is acting as a dynamo,
+only supplying current to a storage battery. On account
+of the varying speeds of the generator, which are due to
+the fluctuation in engine speed, some form of automatic
+switch which will disconnect the generator from the battery
+at such times that the motor speed is not sufficiently
+high to generate a current stronger than that delivered
+by the battery is needed. These automatic switches are
+the only delicate part of the entire apparatus, and while
+they require very delicate adjustment they seem to perform
+very satisfactorily in practice.</p>
+
+<p>When it is desired to start the engine an electrical
+connection is established between the storage battery and
+the motor-generator unit, and this acts as a motor and
+turns the engine over by suitable gearing which engages
+the gear teeth cut into a special gear or disc attached to
+the engine crank-shaft. When the motor-generator furnishes
+current for ignition as well as for starting the
+motor, the fact that the current can be used for this work
+as well as starting justifies to a certain extent the rather<span class='pagenum'><a name="Page_570" id="Page_570">[570]</a></span>
+complicated mechanism which forms a complete starting
+and ignition system, and which may also be used for lighting
+if necessary in night flying.</p>
+
+<p>An electric generator and motor do not complete a
+self-starting system, because some reservoir or container
+for electric current must be provided. The current from
+the generator is usually stored in a storage battery from
+which it can be made to return to the motor or to the
+same armature that produced it. The fundamental units
+of a self-starting system, therefore, are a generator to
+produce the electricity, a storage battery to serve as a
+reservoir, and an electric motor to rotate the motor crank-shaft.
+Generators are usually driven by enclosed gearing,
+though silent chains are used where the center distance
+between the motor shaft and generator shaft is too
+great for the gears. An electric starter may be directly
+connected to the gasoline engine, as is the case where the
+combined motor-generator replaces the fly-wheel in an
+automobile engine. The motor may also drive the engine
+by means of a silent chain or by direct gear reduction.</p>
+
+<p>Every electric starter must use a switch of some kind
+for starting purposes and most systems include an output
+regulator and a reverse current cut-out. The output
+regulator is a simple device that regulates the strength
+of the generator current that is supplied the storage battery.
+A reverse current cut-out is a form of check
+valve that prevents the storage battery from discharging
+through the generator. Brief mention is made of electric
+starting because such systems will undoubtedly be incorporated
+in some future airplane designs. Battery ignition
+is already being experimented with.</p>
+
+<h3><a name="SecXII_24" id="SecXII_24"></a>BATTERY IGNITION SYSTEM PARTS</h3>
+
+<p>A battery ignition system in its simplest form consists
+of a current producer, usually a set of dry cells or a
+storage battery, an induction coil to transform the low
+tension current to one having sufficient strength to jump<span class='pagenum'><a name="Page_571" id="Page_571">[571]</a></span>
+the air gap at the spark-plug, an igniter member placed
+in the combustion chamber and a timer or mechanical
+switch operated by the engine so that the circuit will be
+closed only when it is desired to have a spark take place
+in the cylinders. Battery ignition systems may be of two
+forms, those in which the battery current is stepped up
+or intensified to enable it to jump an air gap between the
+points of the spark plug, these being called &#8220;high tension&#8221;
+systems and the low tension form (never used on
+airplane motors) in which the battery current is not intensified
+to a great degree and a spark produced in the cylinder
+by the action of a mechanical circuit breaker in the
+combustion chamber. The low tension system is the simplest
+electrically but the more complex mechanically.
+The high tension system has the fewest moving parts but
+numerous electrical devices. At the present time all airplane
+engines use high tension ignition systems, the magneto
+being the most popular at the present time. The
+current distribution and timing devices used with modern
+battery systems are practically the same as similar parts
+of a magneto.<span class='pagenum'><a name="Page_572" id="Page_572"></a></span></p>
+
+<hr class="c25" />
+<p class='pagenum'><a name="Page_573" id="Page_573">[573]</a></p>
+<h2><a name="Index" id="Index"></a>INDEX</h2>
+
+<table summary="Index">
+
+<tr>
+<td colspan="2" class="center" style="line-height: 2em;"><span class="fsize125">A</span></td>
+</tr>
+
+<tr>
+<td colspan="2" class="right">PAGE</td>
+</tr>
+
+<tr>
+<td class="left top">Action of Four-cycle Engine</td>
+<td class="right bot"><a href="#Page_38">38</a></td>
+</tr>
+
+<tr>
+<td class="left top">Action of Le Rhone Rotary Engine</td>
+<td class="right bot"><a href="#Page_503">503</a></td>
+</tr>
+
+<tr>
+<td class="left top">Action of Two-cycle Engine</td>
+<td class="right bot"><a href="#Page_41">41</a></td>
+</tr>
+
+<tr>
+<td class="left top">Action of Vacuum Feed System</td>
+<td class="right bot"><a href="#Page_119">119</a></td>
+</tr>
+
+<tr>
+<td class="left top">Actual Duration of Different Functions</td>
+<td class="right bot"><a href="#Page_93">93</a></td>
+</tr>
+
+<tr>
+<td class="left top">Actual Heat Efficiency</td>
+<td class="right bot"><a href="#Page_62">62</a></td>
+</tr>
+
+<tr>
+<td class="left top">Adiabatic Diagram</td>
+<td class="right bot"><a href="#Page_51">51</a></td>
+</tr>
+
+<tr>
+<td class="left top">Adiabatic Law</td>
+<td class="right bot"><a href="#Page_50">50</a></td>
+</tr>
+
+<tr>
+<td class="left top">Adjustment of Bearings</td>
+<td class="right bot"><a href="#Page_449">449</a></td>
+</tr>
+
+<tr>
+<td class="left top">Adjustment of Carburetors</td>
+<td class="right bot"><a href="#Page_151">151</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aerial Motors, Must be Light</td>
+<td class="right bot"><a href="#Page_20">20</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aerial Motors, Operating Conditions of</td>
+<td class="right bot"><a href="#Page_19">19</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aerial Motors, Requirements of</td>
+<td class="right bot"><a href="#Page_19">19</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aeromarine Six-cylinder Engine</td>
+<td class="right bot"><a href="#Page_527">527</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aeronautics, Division in Branches</td>
+<td class="right bot"><a href="#Page_18">18</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aerostatics</td>
+<td class="right bot"><a href="#Page_18">18</a></td>
+</tr>
+
+<tr>
+<td class="left top">Air-cooled Engine Design</td>
+<td class="right bot"><a href="#Page_229">229</a></td>
+</tr>
+
+<tr>
+<td class="left top">Air-cooling Advantages</td>
+<td class="right bot"><a href="#Page_231">231</a></td>
+</tr>
+
+<tr>
+<td class="left top">Air-cooling, Direct Method</td>
+<td class="right bot"><a href="#Page_228">228</a></td>
+</tr>
+
+<tr>
+<td class="left top">Air-cooling Disadvantages</td>
+<td class="right bot"><a href="#Page_231">231</a></td>
+</tr>
+
+<tr>
+<td class="left top">Air-cooling Systems</td>
+<td class="right bot"><a href="#Page_223">223</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aircraft, Heavier Than Air</td>
+<td class="right bot"><a href="#Page_17">17</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aircraft, Lighter Than Air</td>
+<td class="right bot"><a href="#Page_18">18</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aircraft Types, Brief Consideration of</td>
+<td class="right bot"><a href="#Page_17">17</a></td>
+</tr>
+
+<tr>
+<td class="left top">Air Needed to Burn Gasoline</td>
+<td class="right bot"><a href="#Page_113">113</a></td>
+</tr>
+
+<tr>
+<td class="left top">Airplane Engine, Power Needed</td>
+<td class="right bot"><a href="#Page_21">21</a></td>
+</tr>
+
+<tr>
+<td class="left top">Airplane Engines, Overhauling</td>
+<td class="right bot"><a href="#Page_412">412</a></td>
+</tr>
+
+<tr>
+<td class="left top">Airplane Engine, How to Time</td>
+<td class="right bot"><a href="#Page_269">269</a></td>
+</tr>
+
+<tr>
+<td class="left top">Airplane Engine Lubrication</td>
+<td class="right bot"><a href="#Page_209">209</a></td>
+</tr>
+
+<tr>
+<td class="left top">Airplane, How Supported</td>
+<td class="right bot"><a href="#Page_21">21</a></td>
+</tr>
+
+<tr>
+<td class="left top">Airplane Motors, German</td>
+<td class="right bot"><a href="#Page_543">543</a></td>
+</tr>
+
+<tr>
+<td class="left top">Airplane Motor Types</td>
+<td class="right bot"><a href="#Page_20">20</a></td>
+</tr>
+
+<tr>
+<td class="left top">Airplane Motors, Weight of</td>
+<td class="right bot"><a href="#Page_21">21</a></td>
+</tr>
+
+<tr>
+<td class="left top">Airplane Power Plant Installation</td>
+<td class="right bot"><a href="#Page_324">324</a></td>
+</tr>
+
+<tr>
+<td class="left top">Airplane Types</td>
+<td class="right bot"><a href="#Page_18">18</a></td>
+</tr>
+
+<tr>
+<td class="left top">Airplanes, Horse-power Used in</td>
+<td class="right bot"><a href="#Page_26">26</a></td>
+</tr>
+
+<tr>
+<td class="left top">Air Pressure Diminution, With Altitude</td>
+<td class="right bot"><a href="#Page_144">144</a></td>
+</tr>
+
+<tr>
+<td class="left top">Altitude, How it Affects Mixture</td>
+<td class="right bot"><a href="#Page_153">153</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aluminum, Use in Pistons</td>
+<td class="right bot"><a href="#Page_297">297</a></td>
+</tr>
+
+<tr>
+<td class="left top">American Aviation Engines, Statistics<span class='pagenum'><a name="Page_574" id="Page_574">[574]</a></span></td>
+<td class="right bot"><a href="#Page_546">546</a></td>
+</tr>
+
+<tr>
+<td class="left top">Anzani Radial Engine Installation</td>
+<td class="right bot"><a href="#Page_344">344</a></td>
+</tr>
+
+<tr>
+<td class="left top">Anzani Six-cylinder Star Engine</td>
+<td class="right bot"><a href="#Page_465">465</a></td>
+</tr>
+
+<tr>
+<td class="left top">Anzani Six-cylinder Water-cooled Engine</td>
+<td class="right bot"><a href="#Page_459">459</a></td>
+</tr>
+
+<tr>
+<td class="left top">Anzani Ten- and Twenty-cylinder Engines</td>
+<td class="right bot"><a href="#Page_468">468</a></td>
+</tr>
+
+<tr>
+<td class="left top">Anzani Three-cylinder Engine</td>
+<td class="right bot"><a href="#Page_459">459</a></td>
+</tr>
+
+<tr>
+<td class="left top">Anzani Three-cylinder Y Type</td>
+<td class="right bot"><a href="#Page_462">462</a></td>
+</tr>
+
+<tr>
+<td class="left top">Argus Engine Construction</td>
+<td class="right bot"><a href="#Page_545">545</a></td>
+</tr>
+
+<tr>
+<td class="left top">Armature Windings</td>
+<td class="right bot"><a href="#Page_168">168</a></td>
+</tr>
+
+<tr>
+<td class="left top">Atmospheric Conditions, Compensating For</td>
+<td class="right bot"><a href="#Page_143">143</a></td>
+</tr>
+
+<tr>
+<td class="left top">Austro-Daimler Engine</td>
+<td class="right bot"><a href="#Page_557">557</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviatics</td>
+<td class="right bot"><a href="#Page_18">18</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engine, Aeromarine</td>
+<td class="right bot"><a href="#Page_527">527</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engine, Anzani Six-cylinder Star</td>
+<td class="right bot"><a href="#Page_465">465</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engine, Canton and Unn&eacute;</td>
+<td class="right bot"><a href="#Page_469">469</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engine Cooling</td>
+<td class="right bot"><a href="#Page_219">219</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engine, Curtiss</td>
+<td class="right bot"><a href="#Page_519">519</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engine Cylinders</td>
+<td class="right bot"><a href="#Page_233">233</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engine, Early Gnome</td>
+<td class="right bot"><a href="#Page_472">472</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engine, German Gnome Type</td>
+<td class="right bot"><a href="#Page_495">495</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engine, Gnome Monosoupape</td>
+<td class="right bot"><a href="#Page_486">486</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engine, How To Dismantle</td>
+<td class="right bot"><a href="#Page_415">415</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engine, How to Start</td>
+<td class="right bot"><a href="#Page_460">460</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engine, Le Rhone Rotary</td>
+<td class="right bot"><a href="#Page_495">495</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engine Oiling</td>
+<td class="right bot"><a href="#Page_218">218</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engine Parts, Functions of</td>
+<td class="right bot"><a href="#Page_82">82</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engine, Renault Air-cooled</td>
+<td class="right bot"><a href="#Page_507">507</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engine, Stand for Supporting</td>
+<td class="right bot"><a href="#Page_414">414</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engine, Sturtevant</td>
+<td class="right bot"><a href="#Page_515">515</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engine, Thomas-Morse</td>
+<td class="right bot"><a href="#Page_521">521</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engine Types</td>
+<td class="right bot"><a href="#Page_457">457</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engine, Wisconsin</td>
+<td class="right bot"><a href="#Page_531">531</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engines, Anzani Six-cylinder Water-cooled</td>
+<td class="right bot"><a href="#Page_459">459</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engines, Anzani Ten- and Twenty-cylinder</td>
+<td class="right bot"><a href="#Page_468">468</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engines, Anzani Three-cylinder</td>
+<td class="right bot"><a href="#Page_459">459</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engines, Anzani Y Type</td>
+<td class="right bot"><a href="#Page_462">462</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engines, Argus</td>
+<td class="right bot"><a href="#Page_545">545</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engines, Austro-Daimler</td>
+<td class="right bot"><a href="#Page_557">557</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engines, Benz</td>
+<td class="right bot"><a href="#Page_551">551</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engines, Four- and Six-cylinder</td>
+<td class="right bot"><a href="#Page_88">88</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engines, German</td>
+<td class="right bot"><a href="#Page_543">543</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engines, Hall-Scott</td>
+<td class="right bot"><a href="#Page_539">539</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engines, Hispano-Suiza</td>
+<td class="right bot"><a href="#Page_512">512</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engines, Mercedes</td>
+<td class="right bot"><a href="#Page_543">543</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engines, Overhauling</td>
+<td class="right bot"><a href="#Page_412">412</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engines, Principal Parts of</td>
+<td class="right bot"><a href="#Page_80">80</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engines, Starting Systems For</td>
+<td class="right bot"><a href="#Page_567">567</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Engines, Sunbeam</td>
+<td class="right bot"><a href="#Page_558">558</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="center" style="line-height: 2em;"><span class="fsize125">B</span><span
+class='pagenum'><a name="Page_575" id="Page_575">[575]</a></span></td>
+</tr>
+
+<tr>
+<td class="left top">Balanced Crank-shafts</td>
+<td class="right bot"><a href="#Page_318">318</a></td>
+</tr>
+
+<tr>
+<td class="left top">Ball-bearing Crank-shafts</td>
+<td class="right bot"><a href="#Page_319">319</a></td>
+</tr>
+
+<tr>
+<td class="left top">Battery Ignition Systems</td>
+<td class="right bot"><a href="#Page_571">571</a></td>
+</tr>
+
+<tr>
+<td class="left top">Baverey Compound Nozzle</td>
+<td class="right bot"><a href="#Page_137">137</a></td>
+</tr>
+
+<tr>
+<td class="left top">Bearings, Adjustment of</td>
+<td class="right bot"><a href="#Page_449">449</a></td>
+</tr>
+
+<tr>
+<td class="left top">Bearing Alignment</td>
+<td class="right bot"><a href="#Page_453">453</a></td>
+</tr>
+
+<tr>
+<td class="left top">Bearing Brasses, Fitting</td>
+<td class="right bot"><a href="#Page_450">450</a></td>
+</tr>
+
+<tr>
+<td class="left top">Bearing Parallelism, Testing</td>
+<td class="right bot"><a href="#Page_453">453</a></td>
+</tr>
+
+<tr>
+<td class="left top">Bearing Scrapers and Their Use</td>
+<td class="right bot"><a href="#Page_446">446</a></td>
+</tr>
+
+<tr>
+<td class="left top">Benz Aviation Engines</td>
+<td class="right bot"><a href="#Page_551">551</a></td>
+</tr>
+
+<tr>
+<td class="left top">Benz Engine Statistics</td>
+<td class="right bot"><a href="#Page_551">551</a></td>
+</tr>
+
+<tr>
+<td class="left top">Berling Magneto</td>
+<td class="right bot"><a href="#Page_174">174</a></td>
+</tr>
+
+<tr>
+<td class="left top">Berling Magneto, Adjustment of</td>
+<td class="right bot"><a href="#Page_180">180</a></td>
+</tr>
+
+<tr>
+<td class="left top">Berling Magneto Care</td>
+<td class="right bot"><a href="#Page_180">180</a></td>
+</tr>
+
+<tr>
+<td class="left top">Berling Magneto Circuits</td>
+<td class="right bot"><a href="#Page_176">176</a></td>
+</tr>
+
+<tr>
+<td class="left top">Berling Magneto, Setting</td>
+<td class="right bot"><a href="#Page_178">178</a></td>
+</tr>
+
+<tr>
+<td class="left top">Block Castings</td>
+<td class="right bot"><a href="#Page_234">234</a></td>
+</tr>
+
+<tr>
+<td class="left top">Blowing Back</td>
+<td class="right bot"><a href="#Page_269">269</a></td>
+</tr>
+
+<tr>
+<td class="left top">Bolts, Screwing Down</td>
+<td class="right bot"><a href="#Page_452">452</a></td>
+</tr>
+
+<tr>
+<td class="left top">Bore and Stroke Ratio</td>
+<td class="right bot"><a href="#Page_240">240</a></td>
+</tr>
+
+<tr>
+<td class="left top">Boyle&#8217;s Law</td>
+<td class="right bot"><a href="#Page_49">49</a></td>
+</tr>
+
+<tr>
+<td class="left top">Brayton Engine</td>
+<td class="right bot"><a href="#Page_48">48</a></td>
+</tr>
+
+<tr>
+<td class="left top">Breaker Box, Adjustment of</td>
+<td class="right bot"><a href="#Page_180">180</a></td>
+</tr>
+
+<tr>
+<td class="left top">Breast and Hand Drills</td>
+<td class="right bot"><a href="#Page_387">387</a></td>
+</tr>
+
+<tr>
+<td class="left top">Burning Out Carbon Deposits</td>
+<td class="right bot"><a href="#Page_421">421</a></td>
+</tr>
+
+<tr>
+<td class="left top">Bushings, Camshaft, Wear in</td>
+<td class="right bot"><a href="#Page_456">456</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="center" style="line-height: 2em;"><span class="fsize125">C</span></td>
+</tr>
+
+<tr>
+<td class="left top">Calipers, Inside and Outside</td>
+<td class="right bot"><a href="#Page_398">398</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cam Followers, Types of</td>
+<td class="right bot"><a href="#Page_260">260</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cams for Valve Actuation</td>
+<td class="right bot"><a href="#Page_259">259</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cam-shaft Bushings</td>
+<td class="right bot"><a href="#Page_456">456</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cam-shaft Design</td>
+<td class="right bot"><a href="#Page_313">313</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cam-shaft Drive Methods</td>
+<td class="right bot"><a href="#Page_261">261</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cam-shaft Testing</td>
+<td class="right bot"><a href="#Page_451">451</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cam-shafts and Timing Gears</td>
+<td class="right bot"><a href="#Page_456">456</a></td>
+</tr>
+
+<tr>
+<td class="left top">Canton and Unn&eacute; Engine</td>
+<td class="right bot"><a href="#Page_469">469</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carbon, Burning out with Oxygen</td>
+<td class="right bot"><a href="#Page_421">421</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carbon Deposits, Cause of</td>
+<td class="right bot"><a href="#Page_418">418</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carbon Removal</td>
+<td class="right bot"><a href="#Page_419">419</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carbon Scrapers, How Used</td>
+<td class="right bot"><a href="#Page_420">420</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carburetion Principles</td>
+<td class="right bot"><a href="#Page_112">112</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carburetion System Troubles</td>
+<td class="right bot"><a href="#Page_355">355</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carburetor, Claudel</td>
+<td class="right bot"><a href="#Page_127">127</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carburetor, Compound Nozzle Zenith</td>
+<td class="right bot"><a href="#Page_135">135</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carburetor, Concentric Float and Jet Type<span class='pagenum'><a name="Page_576" id="Page_576">[576]</a></span></td>
+<td class="right bot"><a href="#Page_125">125</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carburetor, Duplex Zenith</td>
+<td class="right bot"><a href="#Page_138">138</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carburetor, Duplex Zenith, Trouble in</td>
+<td class="right bot"><a href="#Page_357">357</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carburetor Installation, In Airplanes</td>
+<td class="right bot"><a href="#Page_148">148</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carburetor, Le Rhone</td>
+<td class="right bot"><a href="#Page_501">501</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carburetor, Master Multiple Jet</td>
+<td class="right bot"><a href="#Page_133">133</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carburetor, Schebler</td>
+<td class="right bot"><a href="#Page_125">125</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carburetor Troubles, How to Locate</td>
+<td class="right bot"><a href="#Page_354">354</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carburetor, Two Stage</td>
+<td class="right bot"><a href="#Page_131">131</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carburetor, What it Should Do</td>
+<td class="right bot"><a href="#Page_114">114</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carburetors, Float Feed</td>
+<td class="right bot"><a href="#Page_122">122</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carburetors, Multiple Nozzle</td>
+<td class="right bot"><a href="#Page_130">130</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carburetors, Notes on Adjustment</td>
+<td class="right bot"><a href="#Page_151">151</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carburetors, Reversing Position of</td>
+<td class="right bot"><a href="#Page_149">149</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carburetors, Spraying</td>
+<td class="right bot"><a href="#Page_120">120</a></td>
+</tr>
+
+<tr>
+<td class="left top">Care of Dixie Magneto</td>
+<td class="right bot"><a href="#Page_188">188</a></td>
+</tr>
+
+<tr>
+<td class="left top">Castor Oil, for Cylinder Lubrication</td>
+<td class="right bot"><a href="#Page_205">205</a></td>
+</tr>
+
+<tr>
+<td class="left top">Castor Oil, Why Used In Gnome Engines</td>
+<td class="right bot"><a href="#Page_211">211</a></td>
+</tr>
+
+<tr>
+<td class="left top">Center Gauge</td>
+<td class="right bot"><a href="#Page_403">403</a></td>
+</tr>
+
+<tr>
+<td class="left top">Chisels, Forms of</td>
+<td class="right bot"><a href="#Page_384">384</a></td>
+</tr>
+
+<tr>
+<td class="left top">Christensen Air Starting System</td>
+<td class="right bot"><a href="#Page_567">567</a></td>
+</tr>
+
+<tr>
+<td class="left top">Circuits, Magnetic</td>
+<td class="right bot"><a href="#Page_161">161</a></td>
+</tr>
+
+<tr>
+<td class="left top">Classification of Engines</td>
+<td class="right bot"><a href="#Page_458">458</a></td>
+</tr>
+
+<tr>
+<td class="left top">Claudel Carburetor</td>
+<td class="right bot"><a href="#Page_127">127</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cleaning Distributor</td>
+<td class="right bot"><a href="#Page_180">180</a></td>
+</tr>
+
+<tr>
+<td class="left top">Clearances Between Valve Stem and Actuators</td>
+<td class="right bot"><a href="#Page_261">261</a></td>
+</tr>
+
+<tr>
+<td class="left top">Combustion Chamber Design</td>
+<td class="right bot"><a href="#Page_239">239</a></td>
+</tr>
+
+<tr>
+<td class="left top">Combustion Chambers, Spherical</td>
+<td class="right bot"><a href="#Page_76">76</a></td>
+</tr>
+
+<tr>
+<td class="left top">Common Tools, Outfit of</td>
+<td class="right bot"><a href="#Page_378">378</a></td>
+</tr>
+
+<tr>
+<td class="left top">Comparing Two-cycle and Four-cycle Types</td>
+<td class="right bot"><a href="#Page_44">44</a></td>
+</tr>
+
+<tr>
+<td class="left top">Compound Cam Followers</td>
+<td class="right bot"><a href="#Page_260">260</a></td>
+</tr>
+
+<tr>
+<td class="left top">Compound Piston Rings</td>
+<td class="right bot"><a href="#Page_301">301</a></td>
+</tr>
+
+<tr>
+<td class="left top">Compressed Air Starting System</td>
+<td class="right bot"><a href="#Page_565">565</a></td>
+</tr>
+
+<tr>
+<td class="left top">Compression, Factors Limiting</td>
+<td class="right bot"><a href="#Page_69">69</a></td>
+</tr>
+
+<tr>
+<td class="left top">Compression, in Explosive Motors, Value of</td>
+<td class="right bot"><a href="#Page_68">68</a></td>
+</tr>
+
+<tr>
+<td class="left top">Compression Pressures, Chart for</td>
+<td class="right bot"><a href="#Page_72">72</a></td>
+</tr>
+
+<tr>
+<td class="left top">Compression Temperature</td>
+<td class="right bot"><a href="#Page_71">71</a></td>
+</tr>
+
+<tr>
+<td class="left top">Computations for Horse-power Needed</td>
+<td class="right bot"><a href="#Page_25">25</a></td>
+</tr>
+
+<tr>
+<td class="left top">Computations for Temperature</td>
+<td class="right bot"><a href="#Page_52">52</a></td>
+</tr>
+
+<tr>
+<td class="left top">Concentric Piston Ring</td>
+<td class="right bot"><a href="#Page_299">299</a></td>
+</tr>
+
+<tr>
+<td class="left top">Concentric Valves</td>
+<td class="right bot"><a href="#Page_255">255</a></td>
+</tr>
+
+<tr>
+<td class="left top">Connecting Rod Alignment, Testing</td>
+<td class="right bot"><a href="#Page_454">454</a></td>
+</tr>
+
+<tr>
+<td class="left top">Connecting Rod, Conventional</td>
+<td class="right bot"><a href="#Page_308">308</a></td>
+</tr>
+
+<tr>
+<td class="left top">Connecting Rod Forms</td>
+<td class="right bot"><a href="#Page_305">305</a></td>
+</tr>
+
+<tr>
+<td class="left top">Connecting Rod, Gnome Engine</td>
+<td class="right bot"><a href="#Page_305">305</a></td>
+</tr>
+
+<tr>
+<td class="left top">Connecting Rods, Fitting</td>
+<td class="right bot"><a href="#Page_449">449</a></td>
+</tr>
+
+<tr>
+<td class="left top">Connecting Rods for Vee Engines</td>
+<td class="right bot"><a href="#Page_310">310</a></td>
+</tr>
+
+<tr>
+<td class="left top">Connecting Rods, Le Rhone</td>
+<td class="right bot"><a href="#Page_498">498</a></td>
+</tr>
+
+<tr>
+<td class="left top">Connecting Rods, Master<span class='pagenum'><a name="Page_577" id="Page_577">[577]</a></span></td>
+<td class="right bot"><a href="#Page_310">310</a></td>
+</tr>
+
+<tr>
+<td class="left top">Constant Level Splash System</td>
+<td class="right bot"><a href="#Page_215">215</a></td>
+</tr>
+
+<tr>
+<td class="left top">Construction of Dixie Magneto</td>
+<td class="right bot"><a href="#Page_186">186</a></td>
+</tr>
+
+<tr>
+<td class="left top">Construction of Pistons</td>
+<td class="right bot"><a href="#Page_288">288</a></td>
+</tr>
+
+<tr>
+<td class="left top">Conversion of Heat to Power</td>
+<td class="right bot"><a href="#Page_58">58</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cooling by Air</td>
+<td class="right bot"><a href="#Page_223">223</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cooling by Positive Water Circulation</td>
+<td class="right bot"><a href="#Page_224">224</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cooling, Heat Loss in</td>
+<td class="right bot"><a href="#Page_66">66</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cooling System Defects</td>
+<td class="right bot"><a href="#Page_358">358</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cooling Systems Used</td>
+<td class="right bot"><a href="#Page_223">223</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cooling Systems, Why Needed</td>
+<td class="right bot"><a href="#Page_219">219</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cotter Pin Pliers</td>
+<td class="right bot"><a href="#Page_384">384</a></td>
+</tr>
+
+<tr>
+<td class="left top">Crank-case, Conventional</td>
+<td class="right bot"><a href="#Page_320">320</a></td>
+</tr>
+
+<tr>
+<td class="left top">Crank-case Forms</td>
+<td class="right bot"><a href="#Page_320">320</a></td>
+</tr>
+
+<tr>
+<td class="left top">Crank-case, Gnome</td>
+<td class="right bot"><a href="#Page_323">323</a></td>
+</tr>
+
+<tr>
+<td class="left top">Crank-shaft, Built Up</td>
+<td class="right bot"><a href="#Page_315">315</a></td>
+</tr>
+
+<tr>
+<td class="left top">Crank-shaft Construction</td>
+<td class="right bot"><a href="#Page_315">315</a></td>
+</tr>
+
+<tr>
+<td class="left top">Crank-shaft Design</td>
+<td class="right bot"><a href="#Page_315">315</a></td>
+</tr>
+
+<tr>
+<td class="left top">Crank-shaft Equalizer</td>
+<td class="right bot"><a href="#Page_449">449</a></td>
+</tr>
+
+<tr>
+<td class="left top">Crank-shaft Form</td>
+<td class="right bot"><a href="#Page_315">315</a></td>
+</tr>
+
+<tr>
+<td class="left top">Crank-shaft, Gnome Engine</td>
+<td class="right bot"><a href="#Page_483">483</a></td>
+</tr>
+
+<tr>
+<td class="left top">Crank-shafts, Balanced</td>
+<td class="right bot"><a href="#Page_318">318</a></td>
+</tr>
+
+<tr>
+<td class="left top">Crank-shafts, Ball Bearing</td>
+<td class="right bot"><a href="#Page_319">319</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cross Level</td>
+<td class="right bot"><a href="#Page_403">403</a></td>
+</tr>
+
+<tr>
+<td class="left top">Crude Petroleum, Distillates of</td>
+<td class="right bot"><a href="#Page_111">111</a></td>
+</tr>
+
+<tr>
+<td class="left top">Curtiss Aviation Engines</td>
+<td class="right bot"><a href="#Page_519">519</a></td>
+</tr>
+
+<tr>
+<td class="left top">Curtiss Engine Installation</td>
+<td class="right bot"><a href="#Page_328">328</a></td>
+</tr>
+
+<tr>
+<td class="left top">Curtiss Engine Repairing Tools</td>
+<td class="right bot"><a href="#Page_408">408</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cutting Oil Grooves</td>
+<td class="right bot"><a href="#Page_448">448</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cylinder Blocks, Advantages of</td>
+<td class="right bot"><a href="#Page_237">237</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cylinder Block, Duesenberg</td>
+<td class="right bot"><a href="#Page_235">235</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cylinder Castings, Individual</td>
+<td class="right bot"><a href="#Page_234">234</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cylinder Construction</td>
+<td class="right bot"><a href="#Page_233">233</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cylinder Faults and Correction</td>
+<td class="right bot"><a href="#Page_416">416</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cylinder Form and Crank-shaft Design</td>
+<td class="right bot"><a href="#Page_238">238</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cylinder Head Packings</td>
+<td class="right bot"><a href="#Page_417">417</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cylinder Head, Removable</td>
+<td class="right bot"><a href="#Page_239">239</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cylinder, I Head Form</td>
+<td class="right bot"><a href="#Page_248">248</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cylinder, L Head Form</td>
+<td class="right bot"><a href="#Page_248">248</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cylinder Oils</td>
+<td class="right bot"><a href="#Page_206">206</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cylinder Placing</td>
+<td class="right bot"><a href="#Page_20">20</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cylinder Placing in V Motor</td>
+<td class="right bot"><a href="#Page_99">99</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cylinder Retention, Gnome</td>
+<td class="right bot"><a href="#Page_475">475</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cylinder, T Head Form</td>
+<td class="right bot"><a href="#Page_248">248</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cylinders, Cast in Blocks</td>
+<td class="right bot"><a href="#Page_235">235</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cylinders, Odd Number in Rotary Engines</td>
+<td class="right bot"><a href="#Page_482">482</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cylinders, Repairing Scored</td>
+<td class="right bot"><a href="#Page_423">423</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cylinders, Valve Location in</td>
+<td class="right bot"><a href="#Page_245">245</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="center" style="line-height: 2em;"><span class="fsize125">D</span><span
+class='pagenum'><a name="Page_578" id="Page_578">[578]</a></span></td>
+</tr>
+
+<tr>
+<td class="left top">Defects in Cylinders</td>
+<td class="right bot"><a href="#Page_417">417</a></td>
+</tr>
+
+<tr>
+<td class="left top">Defects in Dry Battery</td>
+<td class="right bot"><a href="#Page_373">373</a></td>
+</tr>
+
+<tr>
+<td class="left top">Defects in Fuel System</td>
+<td class="right bot"><a href="#Page_354">354</a></td>
+</tr>
+
+<tr>
+<td class="left top">Defects in Induction Coil</td>
+<td class="right bot"><a href="#Page_373">373</a></td>
+</tr>
+
+<tr>
+<td class="left top">Defects in Magneto</td>
+<td class="right bot"><a href="#Page_372">372</a></td>
+</tr>
+
+<tr>
+<td class="left top">Defects in Storage Battery</td>
+<td class="right bot"><a href="#Page_372">372</a></td>
+</tr>
+
+<tr>
+<td class="left top">Defects in Timer</td>
+<td class="right bot"><a href="#Page_373">373</a></td>
+</tr>
+
+<tr>
+<td class="left top">Defects in Wiring and Remedies</td>
+<td class="right bot"><a href="#Page_373">373</a></td>
+</tr>
+
+<tr>
+<td class="left top">Die Holder</td>
+<td class="right bot"><a href="#Page_394">394</a></td>
+</tr>
+
+<tr>
+<td class="left top">Dies for Thread Cutting</td>
+<td class="right bot"><a href="#Page_395">395</a></td>
+</tr>
+
+<tr>
+<td class="left top">Diesel Motor Cards</td>
+<td class="right bot"><a href="#Page_67">67</a></td>
+</tr>
+
+<tr>
+<td class="left top">Diesel System</td>
+<td class="right bot"><a href="#Page_144">144</a></td>
+</tr>
+
+<tr>
+<td class="left top">Direct Air Cooling</td>
+<td class="right bot"><a href="#Page_228">228</a></td>
+</tr>
+
+<tr>
+<td class="left top">Dirigible Balloons</td>
+<td class="right bot"><a href="#Page_18">18</a></td>
+</tr>
+
+<tr>
+<td class="left top">Dismantling Airplane Engine</td>
+<td class="right bot"><a href="#Page_415">415</a></td>
+</tr>
+
+<tr>
+<td class="left top">Distillates of Crude Petroleum</td>
+<td class="right bot"><a href="#Page_111">111</a></td>
+</tr>
+
+<tr>
+<td class="left top">Division of Circle in Degrees</td>
+<td class="right bot"><a href="#Page_268">268</a></td>
+</tr>
+
+<tr>
+<td class="left top">Dixie Ignition Magneto</td>
+<td class="right bot"><a href="#Page_184">184</a></td>
+</tr>
+
+<tr>
+<td class="left top">Dixie Magneto, Care of</td>
+<td class="right bot"><a href="#Page_188">188</a></td>
+</tr>
+
+<tr>
+<td class="left top">Draining Oil From Crank-case</td>
+<td class="right bot"><a href="#Page_214">214</a></td>
+</tr>
+
+<tr>
+<td class="left top">Drilling Machines</td>
+<td class="right bot"><a href="#Page_386">386</a></td>
+</tr>
+
+<tr>
+<td class="left top">Drills, Types and Use</td>
+<td class="right bot"><a href="#Page_388">388</a></td>
+</tr>
+
+<tr>
+<td class="left top">Driving Cam-shaft, Methods of</td>
+<td class="right bot"><a href="#Page_262">262</a></td>
+</tr>
+
+<tr>
+<td class="left top">Dry Cell Battery, Defects in</td>
+<td class="right bot"><a href="#Page_373">373</a></td>
+</tr>
+
+<tr>
+<td class="left top">Duesenberg Sixteen Valve Engine</td>
+<td class="right bot"><a href="#Page_525">525</a></td>
+</tr>
+
+<tr>
+<td class="left top">Duesenberg Valve Action</td>
+<td class="right bot"><a href="#Page_255">255</a></td>
+</tr>
+
+<tr>
+<td class="left top">Duplex Zenith Carburetor</td>
+<td class="right bot"><a href="#Page_138">138</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="center" style="line-height: 2em;"><span class="fsize125">E</span></td>
+</tr>
+
+<tr>
+<td class="left top">Early Gnome Motor, Construction of</td>
+<td class="right bot"><a href="#Page_472">472</a></td>
+</tr>
+
+<tr>
+<td class="left top">Early Ignition Systems</td>
+<td class="right bot"><a href="#Page_155">155</a></td>
+</tr>
+
+<tr>
+<td class="left top">Early Types of Gas Engine</td>
+<td class="right bot"><a href="#Page_28">28</a></td>
+</tr>
+
+<tr>
+<td class="left top">Early Vaporizer Forms</td>
+<td class="right bot"><a href="#Page_120">120</a></td>
+</tr>
+
+<tr>
+<td class="left top">Eccentric Piston Ring</td>
+<td class="right bot"><a href="#Page_299">299</a></td>
+</tr>
+
+<tr>
+<td class="left top">Economy, Factors Governing</td>
+<td class="right bot"><a href="#Page_64">64</a></td>
+</tr>
+
+<tr>
+<td class="left top">Efficiency, Actual Heat</td>
+<td class="right bot"><a href="#Page_62">62</a></td>
+</tr>
+
+<tr>
+<td class="left top">Efficiency, Maximum Theoretical</td>
+<td class="right bot"><a href="#Page_61">61</a></td>
+</tr>
+
+<tr>
+<td class="left top">Efficiency, Mechanical</td>
+<td class="right bot"><a href="#Page_62">62</a></td>
+</tr>
+
+<tr>
+<td class="left top">Efficiency of Internal Combustion Engine</td>
+<td class="right bot"><a href="#Page_60">60</a></td>
+</tr>
+
+<tr>
+<td class="left top">Efficiency, Various Measures of</td>
+<td class="right bot"><a href="#Page_61">61</a></td>
+</tr>
+
+<tr>
+<td class="left top">Eight-cylinder Engine</td>
+<td class="right bot"><a href="#Page_95">95</a></td>
+</tr>
+
+<tr>
+<td class="left top">Eight-cylinder Timing Diagram</td>
+<td class="right bot"><a href="#Page_276">276</a></td>
+</tr>
+
+<tr>
+<td class="left top">Electricity and Magnetism, Relation of</td>
+<td class="right bot"><a href="#Page_162">162</a></td>
+</tr>
+
+<tr>
+<td class="left top">Electrical Ignition Best</td>
+<td class="right bot"><a href="#Page_156">156</a></td>
+</tr>
+
+<tr>
+<td class="left top">Electric Starting Systems</td>
+<td class="right bot"><a href="#Page_569">569</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine, Advantages of V Type</td>
+<td class="right bot"><a href="#Page_95">95</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine Base Construction<span class='pagenum'><a name="Page_579" id="Page_579">[579]</a></span></td>
+<td class="right bot"><a href="#Page_319">319</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine Bearings, Adjusting</td>
+<td class="right bot"><a href="#Page_443">443</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine Bearings, Refitting</td>
+<td class="right bot"><a href="#Page_442">442</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine Bed Timbers, Standard</td>
+<td class="right bot"><a href="#Page_330">330</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine, Four-cycle, Action of</td>
+<td class="right bot"><a href="#Page_38">38</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine, Four-cycle, Piston Movements in</td>
+<td class="right bot"><a href="#Page_40">40</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine Functions, Duration of</td>
+<td class="right bot"><a href="#Page_93">93</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine Ignition, Locating Troubles</td>
+<td class="right bot"><a href="#Page_353">353</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine Installation, Gnome</td>
+<td class="right bot"><a href="#Page_344">344</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine Installation, Anzani Radial</td>
+<td class="right bot"><a href="#Page_344">344</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine Installation, Hall-Scott</td>
+<td class="right bot"><a href="#Page_332">332</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine Installation, Rotary</td>
+<td class="right bot"><a href="#Page_342">342</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine Operation, Sequence of</td>
+<td class="right bot"><a href="#Page_84">84</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine Parts and Functions</td>
+<td class="right bot"><a href="#Page_80">80</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine Starts Hard, Ignition Troubles Causing</td>
+<td class="right bot"><a href="#Page_369">369</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine Stoppage, Causes of</td>
+<td class="right bot"><a href="#Page_347">347</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine Temperatures</td>
+<td class="right bot"><a href="#Page_221">221</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine Trouble Charts</td>
+<td class="right bot"><a href="#Page_369">369</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine Troubles, Cooling</td>
+<td class="right bot"><a href="#Page_358">358</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine Troubles, Hints For Locating</td>
+<td class="right bot"><a href="#Page_345">345</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine Troubles, Ignition</td>
+<td class="right bot"><a href="#Page_353">353</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine Troubles, Noisy Operation</td>
+<td class="right bot"><a href="#Page_359">359</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine Troubles, Oiling</td>
+<td class="right bot"><a href="#Page_357">357</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine Troubles Summarized</td>
+<td class="right bot"><a href="#Page_350">350</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engine, Two-cycle, Action of</td>
+<td class="right bot"><a href="#Page_41">41</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engines, Classification of</td>
+<td class="right bot"><a href="#Page_458">458</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engines, Cylinder Arrangement</td>
+<td class="right bot"><a href="#Page_31">31</a>-<a href="#Page_32">32</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engines, Eight-cylinder V</td>
+<td class="right bot"><a href="#Page_95">95</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engines, Four-cylinder Forms</td>
+<td class="right bot"><a href="#Page_88">88</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engines, Graphic Comparison of</td>
+<td class="right bot"><a href="#Page_33">33</a>-<a href="#Page_34">34</a>-<a href="#Page_35">35</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engines, Internal Combustion, Types of</td>
+<td class="right bot"><a href="#Page_30">30</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engines, Multiple Cylinder, Power Delivery in</td>
+<td class="right bot"><a href="#Page_91">91</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engines, Multiple Cylinder, Why Best</td>
+<td class="right bot"><a href="#Page_83">83</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engines, Rotary Cylinder</td>
+<td class="right bot"><a href="#Page_107">107</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engines, Six-cylinder Forms</td>
+<td class="right bot"><a href="#Page_88">88</a></td>
+</tr>
+
+<tr>
+<td class="left top">Engines, Twelve-cylinder</td>
+<td class="right bot"><a href="#Page_96">96</a></td>
+</tr>
+
+<tr>
+<td class="left top">Equalizer, Crank-shaft</td>
+<td class="right bot"><a href="#Page_449">449</a></td>
+</tr>
+
+<tr>
+<td class="left top">Exhaust Closing</td>
+<td class="right bot"><a href="#Page_270">270</a></td>
+</tr>
+
+<tr>
+<td class="left top">Exhaust Valve Design, Early Gnome</td>
+<td class="right bot"><a href="#Page_475">475</a></td>
+</tr>
+
+<tr>
+<td class="left top">Exhaust Valve Opening</td>
+<td class="right bot"><a href="#Page_270">270</a></td>
+</tr>
+
+<tr>
+<td class="left top">Explosive Gases, Mixtures of</td>
+<td class="right bot"><a href="#Page_56">56</a></td>
+</tr>
+
+<tr>
+<td class="left top">Explosive Motors, Inefficiency in</td>
+<td class="right bot"><a href="#Page_74">74</a></td>
+</tr>
+
+<tr>
+<td class="left top">Explosive Motors, Why Best</td>
+<td class="right bot"><a href="#Page_27">27</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="center" style="line-height: 2em;"><span class="fsize125">F</span></td>
+</tr>
+
+<tr>
+<td class="left top">Factors Governing Economy</td>
+<td class="right bot"><a href="#Page_64">64</a></td>
+</tr>
+
+<tr>
+<td class="left top">Factors Limiting Compression</td>
+<td class="right bot"><a href="#Page_70">70</a></td>
+</tr>
+
+<tr>
+<td class="left top">Faults in Ignition</td>
+<td class="right bot"><a href="#Page_352">352</a></td>
+</tr>
+
+<tr>
+<td class="left top">Figuring Horse-power Needed<span class='pagenum'><a name="Page_580" id="Page_580">[580]</a></span></td>
+<td class="right bot"><a href="#Page_21">21</a></td>
+</tr>
+
+<tr>
+<td class="left top">Files, Use and Care of</td>
+<td class="right bot"><a href="#Page_383">383</a></td>
+</tr>
+
+<tr>
+<td class="left top">First Law of Gases</td>
+<td class="right bot"><a href="#Page_49">49</a></td>
+</tr>
+
+<tr>
+<td class="left top">Fitting Bearings By Scraping</td>
+<td class="right bot"><a href="#Page_447">447</a></td>
+</tr>
+
+<tr>
+<td class="left top">Fitting Brasses</td>
+<td class="right bot"><a href="#Page_450">450</a></td>
+</tr>
+
+<tr>
+<td class="left top">Fitting Connecting Rods</td>
+<td class="right bot"><a href="#Page_449">449</a></td>
+</tr>
+
+<tr>
+<td class="left top">Fitting Main Bearings</td>
+<td class="right bot"><a href="#Page_448">448</a></td>
+</tr>
+
+<tr>
+<td class="left top">Fitting Piston Rings</td>
+<td class="right bot"><a href="#Page_439">439</a></td>
+</tr>
+
+<tr>
+<td class="left top">Float Feed Carburetor Development</td>
+<td class="right bot"><a href="#Page_124">124</a></td>
+</tr>
+
+<tr>
+<td class="left top">Float Feed Carburetors</td>
+<td class="right bot"><a href="#Page_122">122</a></td>
+</tr>
+
+<tr>
+<td class="left top">Force Feed Oiling System</td>
+<td class="right bot"><a href="#Page_218">218</a></td>
+</tr>
+
+<tr>
+<td class="left top">Forked Connecting Rods</td>
+<td class="right bot"><a href="#Page_310">310</a></td>
+</tr>
+
+<tr>
+<td class="left top">Four-cycle Engine, Action of</td>
+<td class="right bot"><a href="#Page_38">38</a></td>
+</tr>
+
+<tr>
+<td class="left top">Four-cycle Engine, Why Best</td>
+<td class="right bot"><a href="#Page_45">45</a></td>
+</tr>
+
+<tr>
+<td class="left top">Fourteen-cylinder Engine</td>
+<td class="right bot"><a href="#Page_474">474</a></td>
+</tr>
+
+<tr>
+<td class="left top">Four Valves Per Cylinder</td>
+<td class="right bot"><a href="#Page_284">284</a></td>
+</tr>
+
+<tr>
+<td class="left top">Friction, Definition of</td>
+<td class="right bot"><a href="#Page_302">302</a></td>
+</tr>
+
+<tr>
+<td class="left top">Fuel Feed By Gravity</td>
+<td class="right bot"><a href="#Page_116">116</a></td>
+</tr>
+
+<tr>
+<td class="left top">Fuel Feed by Vacuum Tank</td>
+<td class="right bot"><a href="#Page_117">117</a></td>
+</tr>
+
+<tr>
+<td class="left top">Fuel Storage and Supply</td>
+<td class="right bot"><a href="#Page_116">116</a></td>
+</tr>
+
+<tr>
+<td class="left top">Fuel Strainers, Types of</td>
+<td class="right bot"><a href="#Page_141">141</a></td>
+</tr>
+
+<tr>
+<td class="left top">Fuel Strainers, Utility of</td>
+<td class="right bot"><a href="#Page_140">140</a></td>
+</tr>
+
+<tr>
+<td class="left top">Fuel System Faults</td>
+<td class="right bot"><a href="#Page_354">354</a></td>
+</tr>
+
+<tr>
+<td class="left top">Fuel System Installation, Hall-Scott</td>
+<td class="right bot"><a href="#Page_336">336</a></td>
+</tr>
+
+<tr>
+<td class="left top">Fuel System, Gnome</td>
+<td class="right bot"><a href="#Page_490">490</a></td>
+</tr>
+
+<tr>
+<td class="left top">Fuel Utilization Chart</td>
+<td class="right bot"><a href="#Page_62">62</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="center" style="line-height: 2em;"><span class="fsize125">G</span></td>
+</tr>
+
+<tr>
+<td class="left top">Gas Engine, Beau de Rocha&#8217;s Principles</td>
+<td class="right bot"><a href="#Page_59">59</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gas Engine Development</td>
+<td class="right bot"><a href="#Page_28">28</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gas Engine, Early Forms of</td>
+<td class="right bot"><a href="#Page_48">48</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gas Engine, Inventors of</td>
+<td class="right bot"><a href="#Page_29">29</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gas Engine, Theory of</td>
+<td class="right bot"><a href="#Page_47">47</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gases, Compression of</td>
+<td class="right bot"><a href="#Page_49">49</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gases, First Law of</td>
+<td class="right bot"><a href="#Page_49">49</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gases, Second Law of</td>
+<td class="right bot"><a href="#Page_50">50</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gaskets, How to Use</td>
+<td class="right bot"><a href="#Page_452">452</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gasoline, Air Needed to Burn</td>
+<td class="right bot"><a href="#Page_113">113</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gas Engines, Parts of</td>
+<td class="right bot"><a href="#Page_80">80</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gas Vacuum Engine, Brown&#8217;s</td>
+<td class="right bot"><a href="#Page_28">28</a></td>
+</tr>
+
+<tr>
+<td class="left top">German Airplane Motors</td>
+<td class="right bot"><a href="#Page_543">543</a></td>
+</tr>
+
+<tr>
+<td class="left top">German Gnome Type Engine</td>
+<td class="right bot"><a href="#Page_495">495</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gnome Aviation Engine, Early Form</td>
+<td class="right bot"><a href="#Page_472">472</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gnome Crank-shaft</td>
+<td class="right bot"><a href="#Page_483">483</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gnome Cylinder, Machining</td>
+<td class="right bot"><a href="#Page_489">489</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gnome Cylinder Retention</td>
+<td class="right bot"><a href="#Page_475">475</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gnome Engine, Fuel, Lubrication and Ignition</td>
+<td class="right bot"><a href="#Page_490">490</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gnome Engine, German Type<span class='pagenum'><a name="Page_581" id="Page_581">[581]</a></span></td>
+<td class="right bot"><a href="#Page_495">495</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gnome Engine Installation</td>
+<td class="right bot"><a href="#Page_344">344</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gnome Firing Order</td>
+<td class="right bot"><a href="#Page_482">482</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gnome Fourteen-cylinder, Engine</td>
+<td class="right bot"><a href="#Page_474">474</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gnome Fourteen-cylinder Engine Details</td>
+<td class="right bot"><a href="#Page_480">480</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gnome Monosoupape, How to Time</td>
+<td class="right bot"><a href="#Page_278">278</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gnome Monosoupape Type Engine</td>
+<td class="right bot"><a href="#Page_486">486</a></td>
+</tr>
+
+<tr>
+<td class="left top">Graphic Comparison of Engine Types</td>
+<td class="right bot"><a href="#Page_33">33</a>-<a href="#Page_34">34</a>-<a href="#Page_35">35</a></td>
+</tr>
+
+<tr>
+<td class="left top">Graphic Comparison, Two- and Four-cycle</td>
+<td class="right bot"><a href="#Page_46">46</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gravity Feed System</td>
+<td class="right bot"><a href="#Page_116">116</a></td>
+</tr>
+
+<tr>
+<td class="left top">Grinding Valves</td>
+<td class="right bot"><a href="#Page_429">429</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="center" style="line-height: 2em;"><span class="fsize125">H</span></td>
+</tr>
+
+<tr>
+<td class="left top">Hall-Scott Aviation Engines</td>
+<td class="right bot"><a href="#Page_539">539</a></td>
+</tr>
+
+<tr>
+<td class="left top">Hall-Scott Engine Installation</td>
+<td class="right bot"><a href="#Page_332">332</a></td>
+</tr>
+
+<tr>
+<td class="left top">Hall-Scott Engine, Preparations For Starting</td>
+<td class="right bot"><a href="#Page_341">341</a></td>
+</tr>
+
+<tr>
+<td class="left top">Hall-Scott Engine Tools</td>
+<td class="right bot"><a href="#Page_410">410</a></td>
+</tr>
+
+<tr>
+<td class="left top">Hall-Scott Lubrication System</td>
+<td class="right bot"><a href="#Page_211">211</a></td>
+</tr>
+
+<tr>
+<td class="left top">Hall-Scott Statistic Sheet</td>
+<td class="right bot"><a href="#Page_544">544</a></td>
+</tr>
+
+<tr>
+<td class="left top">Heat and Its Work</td>
+<td class="right bot"><a href="#Page_54">54</a></td>
+</tr>
+
+<tr>
+<td class="left top">Heat in Gas Engine Cylinder</td>
+<td class="right bot"><a href="#Page_69">69</a></td>
+</tr>
+
+<tr>
+<td class="left top">Heat Given to Cooling Water</td>
+<td class="right bot"><a href="#Page_78">78</a></td>
+</tr>
+
+<tr>
+<td class="left top">Heat Loss, Causes of</td>
+<td class="right bot"><a href="#Page_74">74</a></td>
+</tr>
+
+<tr>
+<td class="left top">Heat Loss in Airplane Engine</td>
+<td class="right bot"><a href="#Page_221">221</a></td>
+</tr>
+
+<tr>
+<td class="left top">Heat Loss in Wall Cooling</td>
+<td class="right bot"><a href="#Page_65">65</a></td>
+</tr>
+
+<tr>
+<td class="left top">High Altitude, How it Affects Power</td>
+<td class="right bot"><a href="#Page_144">144</a></td>
+</tr>
+
+<tr>
+<td class="left top">High Tension Magneto</td>
+<td class="right bot"><a href="#Page_172">172</a></td>
+</tr>
+
+<tr>
+<td class="left top">Hints For Locating Engine Troubles</td>
+<td class="right bot"><a href="#Page_345">345</a></td>
+</tr>
+
+<tr>
+<td class="left top">Hints for Starting Engine</td>
+<td class="right bot"><a href="#Page_361">361</a></td>
+</tr>
+
+<tr>
+<td class="left top">Hispano-Suiza Model A Engine</td>
+<td class="right bot"><a href="#Page_512">512</a></td>
+</tr>
+
+<tr>
+<td class="left top">Horse-power Needed in Airplane</td>
+<td class="right bot"><a href="#Page_21">21</a></td>
+</tr>
+
+<tr>
+<td class="left top">Horse-power Needed, How Figured</td>
+<td class="right bot"><a href="#Page_22">22</a></td>
+</tr>
+
+<tr>
+<td class="left top">How An Engine is Timed</td>
+<td class="right bot"><a href="#Page_277">277</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="center" style="line-height: 2em;"><span class="fsize125">I</span></td>
+</tr>
+
+<tr>
+<td class="left top">Ignition, Electric</td>
+<td class="right bot"><a href="#Page_156">156</a></td>
+</tr>
+
+<tr>
+<td class="left top">Ignition, Elements of</td>
+<td class="right bot"><a href="#Page_157">157</a></td>
+</tr>
+
+<tr>
+<td class="left top">Ignition of Gnome Engine</td>
+<td class="right bot"><a href="#Page_490">490</a></td>
+</tr>
+
+<tr>
+<td class="left top">Ignition System, Battery</td>
+<td class="right bot"><a href="#Page_571">571</a></td>
+</tr>
+
+<tr>
+<td class="left top">Ignition Systems, Early</td>
+<td class="right bot"><a href="#Page_155">155</a></td>
+</tr>
+
+<tr>
+<td class="left top">Ignition System Faults</td>
+<td class="right bot"><a href="#Page_352">352</a></td>
+</tr>
+
+<tr>
+<td class="left top">Ignition, Time of</td>
+<td class="right bot"><a href="#Page_273">273</a></td>
+</tr>
+
+<tr>
+<td class="left top">Ignition, Two Spark</td>
+<td class="right bot"><a href="#Page_196">196</a></td>
+</tr>
+
+<tr>
+<td class="left top">I Head Cylinders</td>
+<td class="right bot"><a href="#Page_248">248</a></td>
+</tr>
+
+<tr>
+<td class="left top">Improvements in Gas Engines</td>
+<td class="right bot"><a href="#Page_29">29</a></td>
+</tr>
+
+<tr>
+<td class="left top">Indicating Meters, Engine Speed</td>
+<td class="right bot"><a href="#Page_563">563</a></td>
+</tr>
+
+<tr>
+<td class="left top">Indicating Meters, Oil and Air Pressure<span class='pagenum'><a name="Page_582" id="Page_582">[582]</a></span></td>
+<td class="right bot"><a href="#Page_563">563</a></td>
+</tr>
+
+<tr>
+<td class="left top">Indicator Cards, How To Read</td>
+<td class="right bot"><a href="#Page_66">66</a></td>
+</tr>
+
+<tr>
+<td class="left top">Indicator Cards, Value of</td>
+<td class="right bot"><a href="#Page_66">66</a></td>
+</tr>
+
+<tr>
+<td class="left top">Individual Cylinder Castings</td>
+<td class="right bot"><a href="#Page_234">234</a></td>
+</tr>
+
+<tr>
+<td class="left top">Induction Coil, Defects in</td>
+<td class="right bot"><a href="#Page_373">373</a></td>
+</tr>
+
+<tr>
+<td class="left top">Inefficiency, Causes of</td>
+<td class="right bot"><a href="#Page_74">74</a></td>
+</tr>
+
+<tr>
+<td class="left top">Inlet Valve Closing</td>
+<td class="right bot"><a href="#Page_272">272</a></td>
+</tr>
+
+<tr>
+<td class="left top">Inlet Valve Opening</td>
+<td class="right bot"><a href="#Page_270">270</a></td>
+</tr>
+
+<tr>
+<td class="left top">Installation, Airplane Engine</td>
+<td class="right bot"><a href="#Page_324">324</a></td>
+</tr>
+
+<tr>
+<td class="left top">Installation, Curtiss OX-2 Engine</td>
+<td class="right bot"><a href="#Page_328">328</a></td>
+</tr>
+
+<tr>
+<td class="left top">Installation, Hall-Scott Engine</td>
+<td class="right bot"><a href="#Page_332">332</a></td>
+</tr>
+
+<tr>
+<td class="left top">Installation of Rotary Engines</td>
+<td class="right bot"><a href="#Page_342">342</a></td>
+</tr>
+
+<tr>
+<td class="left top">Intake Manifold Construction</td>
+<td class="right bot"><a href="#Page_143">143</a></td>
+</tr>
+
+<tr>
+<td class="left top">Intake Manifold Design</td>
+<td class="right bot"><a href="#Page_142">142</a></td>
+</tr>
+
+<tr>
+<td class="left top">Internal Combustion Engine, Efficiency of</td>
+<td class="right bot"><a href="#Page_60">60</a>, <a href="#Page_62">62</a></td>
+</tr>
+
+<tr>
+<td class="left top">Internal Combustion Engines, Main Types of</td>
+<td class="right bot"><a href="#Page_30">30</a></td>
+</tr>
+
+<tr>
+<td class="left top">Inverted Engine Placing</td>
+<td class="right bot"><a href="#Page_325">325</a></td>
+</tr>
+
+<tr>
+<td class="left top">Isothermal Diagram</td>
+<td class="right bot"><a href="#Page_51">51</a></td>
+</tr>
+
+<tr>
+<td class="left top">Isothermal Law</td>
+<td class="right bot"><a href="#Page_48">48</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="center" style="line-height: 2em;"><span class="fsize125">K</span></td>
+</tr>
+
+<tr>
+<td class="left top">Keeping Oil Out of Combustion Chamber</td>
+<td class="right bot"><a href="#Page_303">303</a></td>
+</tr>
+
+<tr>
+<td class="left top">Knight Sleeve Valves</td>
+<td class="right bot"><a href="#Page_266">266</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="center" style="line-height: 2em;"><span class="fsize125">L</span></td>
+</tr>
+
+<tr>
+<td class="left top">Lag and Lead, Explanation of</td>
+<td class="right bot"><a href="#Page_268">268</a></td>
+</tr>
+
+<tr>
+<td class="left top">Lapping Crank-pins</td>
+<td class="right bot"><a href="#Page_445">445</a></td>
+</tr>
+
+<tr>
+<td class="left top">Lead Given Exhaust Valve</td>
+<td class="right bot"><a href="#Page_270">270</a></td>
+</tr>
+
+<tr>
+<td class="left top">Leak Proof Piston Rings</td>
+<td class="right bot"><a href="#Page_301">301</a></td>
+</tr>
+
+<tr>
+<td class="left top">Lenoir Engine Action</td>
+<td class="right bot"><a href="#Page_48">48</a></td>
+</tr>
+
+<tr>
+<td class="left top">Le Rhone Cams and Valve Actuation</td>
+<td class="right bot"><a href="#Page_500">500</a></td>
+</tr>
+
+<tr>
+<td class="left top">Le Rhone Carburetor</td>
+<td class="right bot"><a href="#Page_501">501</a></td>
+</tr>
+
+<tr>
+<td class="left top">Le Rhone Connecting Rod Assembly, Distinctive</td>
+<td class="right bot"><a href="#Page_498">498</a></td>
+</tr>
+
+<tr>
+<td class="left top">Le Rhone Engine Action</td>
+<td class="right bot"><a href="#Page_503">503</a></td>
+</tr>
+
+<tr>
+<td class="left top">Le Rhone Rotary Engine</td>
+<td class="right bot"><a href="#Page_495">495</a></td>
+</tr>
+
+<tr>
+<td class="left top">L Head Cylinders</td>
+<td class="right bot"><a href="#Page_248">248</a></td>
+</tr>
+
+<tr>
+<td class="left top">Liquid Fuels, Properties of</td>
+<td class="right bot"><a href="#Page_110">110</a></td>
+</tr>
+
+<tr>
+<td class="left top">Locating Carburetor Troubles</td>
+<td class="right bot"><a href="#Page_354">354</a></td>
+</tr>
+
+<tr>
+<td class="left top">Locating Engine Troubles</td>
+<td class="right bot"><a href="#Page_350">350</a></td>
+</tr>
+
+<tr>
+<td class="left top">Locating Ignition Troubles</td>
+<td class="right bot"><a href="#Page_353">353</a></td>
+</tr>
+
+<tr>
+<td class="left top">Locating Oiling Troubles</td>
+<td class="right bot"><a href="#Page_357">357</a></td>
+</tr>
+
+<tr>
+<td class="left top">Location of Magneto Trouble</td>
+<td class="right bot"><a href="#Page_181">181</a></td>
+</tr>
+
+<tr>
+<td class="left top">Losses in Wall Cooling</td>
+<td class="right bot"><a href="#Page_65">65</a></td>
+</tr>
+
+<tr>
+<td class="left top">Lost Power and Overheating, Summary of Troubles Causing</td>
+<td class="right bot"><a href="#Page_363">363</a></td>
+</tr>
+
+<tr>
+<td class="left top">Lubricants, Derivation of</td>
+<td class="right bot"><a href="#Page_204">204</a></td>
+</tr>
+
+<tr>
+<td class="left top">Lubricants, Requirements of</td>
+<td class="right bot"><a href="#Page_204">204</a></td>
+</tr>
+
+<tr>
+<td class="left top">Lubricating System Classification<span class='pagenum'><a name="Page_583" id="Page_583">[583]</a></span></td>
+<td class="right bot"><a href="#Page_208">208</a></td>
+</tr>
+
+<tr>
+<td class="left top">Lubricating Systems, Selection of</td>
+<td class="right bot"><a href="#Page_208">208</a></td>
+</tr>
+
+<tr>
+<td class="left top">Lubrication By Constant Level Splash System</td>
+<td class="right bot"><a href="#Page_215">215</a></td>
+</tr>
+
+<tr>
+<td class="left top">Lubrication By Dry Crank-case Method</td>
+<td class="right bot"><a href="#Page_218">218</a></td>
+</tr>
+
+<tr>
+<td class="left top">Lubrication By Force Feed Best</td>
+<td class="right bot"><a href="#Page_218">218</a></td>
+</tr>
+
+<tr>
+<td class="left top">Lubrication of Magneto</td>
+<td class="right bot"><a href="#Page_180">180</a></td>
+</tr>
+
+<tr>
+<td class="left top">Lubrication System, Gnome</td>
+<td class="right bot"><a href="#Page_490">490</a></td>
+</tr>
+
+<tr>
+<td class="left top">Lubrication System, Hall-Scott</td>
+<td class="right bot"><a href="#Page_211">211</a></td>
+</tr>
+
+<tr>
+<td class="left top">Lubrication System, Thomas-Morse</td>
+<td class="right bot"><a href="#Page_210">210</a></td>
+</tr>
+
+<tr>
+<td class="left top">Lubrication, Theory of</td>
+<td class="right bot"><a href="#Page_202">202</a></td>
+</tr>
+
+<tr>
+<td class="left top">Lubrication, Why Necessary</td>
+<td class="right bot"><a href="#Page_201">201</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="center" style="line-height: 2em;"><span class="fsize125">M</span></td>
+</tr>
+
+<tr>
+<td class="left top">Magnetic Circuits</td>
+<td class="right bot"><a href="#Page_161">161</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magnetic Influence Defined</td>
+<td class="right bot"><a href="#Page_158">158</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magnetic Lines of Force</td>
+<td class="right bot"><a href="#Page_161">161</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magnetic Substances</td>
+<td class="right bot"><a href="#Page_158">158</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magnetism, Flow Through Armature</td>
+<td class="right bot"><a href="#Page_166">166</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magnetism, Fundamentals of</td>
+<td class="right bot"><a href="#Page_157">157</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magnetism, Relation to Electricity</td>
+<td class="right bot"><a href="#Page_162">162</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magneto, Action of High Tension</td>
+<td class="right bot"><a href="#Page_173">173</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magneto Armature Windings</td>
+<td class="right bot"><a href="#Page_168">168</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magneto, Basic Principles of</td>
+<td class="right bot"><a href="#Page_163">163</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magneto, Berling</td>
+<td class="right bot"><a href="#Page_174">174</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magneto, Defects in</td>
+<td class="right bot"><a href="#Page_372">372</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magneto Distributor, Cleaning</td>
+<td class="right bot"><a href="#Page_180">180</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magneto Ignition Systems</td>
+<td class="right bot"><a href="#Page_169">169</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magneto Ignition Wiring</td>
+<td class="right bot"><a href="#Page_179">179</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magneto Interrupter, Adjustment of</td>
+<td class="right bot"><a href="#Page_180">180</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magneto, Low Voltage</td>
+<td class="right bot"><a href="#Page_168">168</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magneto, Lubrication of</td>
+<td class="right bot"><a href="#Page_180">180</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magneto Maintenance</td>
+<td class="right bot"><a href="#Page_180">180</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magneto, Method of Driving</td>
+<td class="right bot"><a href="#Page_175">175</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magneto Parts and Functions</td>
+<td class="right bot"><a href="#Page_167">167</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magneto, The Dixie</td>
+<td class="right bot"><a href="#Page_184">184</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magneto Timing</td>
+<td class="right bot"><a href="#Page_179">179</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magneto, Timing Dixie</td>
+<td class="right bot"><a href="#Page_188">188</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magneto, Transformer System</td>
+<td class="right bot"><a href="#Page_171">171</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magneto Trouble, Location of</td>
+<td class="right bot"><a href="#Page_181">181</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magneto, True High Tension</td>
+<td class="right bot"><a href="#Page_172">172</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magneto, Two Spark Dual</td>
+<td class="right bot"><a href="#Page_177">177</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magnets, Forms of</td>
+<td class="right bot"><a href="#Page_160">160</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magnets, How Produced</td>
+<td class="right bot"><a href="#Page_162">162</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magnets, Properties of</td>
+<td class="right bot"><a href="#Page_159">159</a></td>
+</tr>
+
+<tr>
+<td class="left top">Main Bearings, Fitting</td>
+<td class="right bot"><a href="#Page_448">448</a></td>
+</tr>
+
+<tr>
+<td class="left top">Manifold, Intake</td>
+<td class="right bot"><a href="#Page_143">143</a></td>
+</tr>
+
+<tr>
+<td class="left top">Master Multiple Jet Carburetor</td>
+<td class="right bot"><a href="#Page_133">133</a></td>
+</tr>
+
+<tr>
+<td class="left top">Master Rod Construction<span class='pagenum'><a name="Page_584" id="Page_584">[584]</a></span></td>
+<td class="right bot"><a href="#Page_310">310</a></td>
+</tr>
+
+<tr>
+<td class="left top">Maximum Theoretical Efficiency</td>
+<td class="right bot"><a href="#Page_61">61</a></td>
+</tr>
+
+<tr>
+<td class="left top">Meaning of Piston Speed</td>
+<td class="right bot"><a href="#Page_241">241</a></td>
+</tr>
+
+<tr>
+<td class="left top">Measures of Efficiency</td>
+<td class="right bot"><a href="#Page_61">61</a></td>
+</tr>
+
+<tr>
+<td class="left top">Measuring Tools</td>
+<td class="right bot"><a href="#Page_397">397</a></td>
+</tr>
+
+<tr>
+<td class="left top">Mechanical Efficiency</td>
+<td class="right bot"><a href="#Page_62">62</a></td>
+</tr>
+
+<tr>
+<td class="left top">Mercedes Aviation Engine</td>
+<td class="right bot"><a href="#Page_543">543</a></td>
+</tr>
+
+<tr>
+<td class="left top">Metering Pin Carburetor, Stewart</td>
+<td class="right bot"><a href="#Page_128">128</a></td>
+</tr>
+
+<tr>
+<td class="left top">Micrometer Caliper, Beading</td>
+<td class="right bot"><a href="#Page_405">405</a></td>
+</tr>
+
+<tr>
+<td class="left top">Micrometer Calipers, Types and Use</td>
+<td class="right bot"><a href="#Page_404">404</a></td>
+</tr>
+
+<tr>
+<td class="left top">Mixture, Effect of Altitude on</td>
+<td class="right bot"><a href="#Page_153">153</a></td>
+</tr>
+
+<tr>
+<td class="left top">Mixture, Proportions of</td>
+<td class="right bot"><a href="#Page_151">151</a></td>
+</tr>
+
+<tr>
+<td class="left top">Mixture, Starvation of</td>
+<td class="right bot"><a href="#Page_149">149</a></td>
+</tr>
+
+<tr>
+<td class="left top">Monosoupape Gnome Engine</td>
+<td class="right bot"><a href="#Page_486">486</a></td>
+</tr>
+
+<tr>
+<td class="left top">Mother Bod, Gnome Engine</td>
+<td class="right bot"><a href="#Page_305">305</a></td>
+</tr>
+
+<tr>
+<td class="left top">Motor Misfires, Carburetor Faults Causing</td>
+<td class="right bot"><a href="#Page_374">374</a></td>
+</tr>
+
+<tr>
+<td class="left top">Motor Misfires, Ignition Troubles Causing</td>
+<td class="right bot"><a href="#Page_370">370</a></td>
+</tr>
+
+<tr>
+<td class="left top">Motor Races, Carburetor Faults Causing</td>
+<td class="right bot"><a href="#Page_374">374</a></td>
+</tr>
+
+<tr>
+<td class="left top">Motor Starts Hard, Carburetor Faults Causing</td>
+<td class="right bot"><a href="#Page_374">374</a></td>
+</tr>
+
+<tr>
+<td class="left top">Motor Stops In Flight, Carburetor Faults</td>
+<td class="right bot"><a href="#Page_374">374</a></td>
+</tr>
+
+<tr>
+<td class="left top">Motor Stops Without Warning, Ignition Troubles</td>
+<td class="right bot"><a href="#Page_370">370</a></td>
+</tr>
+
+<tr>
+<td class="left top">Multiple Cylinder Engine, Why Best</td>
+<td class="right bot"><a href="#Page_83">83</a></td>
+</tr>
+
+<tr>
+<td class="left top">Multiple Nozzle Vaporizers</td>
+<td class="right bot"><a href="#Page_129">129</a></td>
+</tr>
+
+<tr>
+<td class="left top">Multiple Valve Advantages</td>
+<td class="right bot"><a href="#Page_286">286</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="center" style="line-height: 2em;"><span class="fsize125">N</span></td>
+</tr>
+
+<tr>
+<td class="left top">Noisy Engine Operation, Causes of</td>
+<td class="right bot"><a href="#Page_359">359</a></td>
+</tr>
+
+<tr>
+<td class="left top">Noisy Operation, Carburetor Faults Causing</td>
+<td class="right bot"><a href="#Page_374">374</a></td>
+</tr>
+
+<tr>
+<td class="left top">Noisy Operation, Summary of Troubles Causing</td>
+<td class="right bot"><a href="#Page_365">365</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="center" style="line-height: 2em;"><span class="fsize125">O</span></td>
+</tr>
+
+<tr>
+<td class="left top">Off-set Cylinders, Reason for</td>
+<td class="right bot"><a href="#Page_243">243</a></td>
+</tr>
+
+<tr>
+<td class="left top">Oil Bi-pass, Function of</td>
+<td class="right bot"><a href="#Page_213">213</a></td>
+</tr>
+
+<tr>
+<td class="left top">Oil, Draining From Crank-case</td>
+<td class="right bot"><a href="#Page_214">214</a></td>
+</tr>
+
+<tr>
+<td class="left top">Oil Grooves, Cutting</td>
+<td class="right bot"><a href="#Page_448">448</a></td>
+</tr>
+
+<tr>
+<td class="left top">Oil Pressure in Hall-Scott System</td>
+<td class="right bot"><a href="#Page_214">214</a></td>
+</tr>
+
+<tr>
+<td class="left top">Oil Pressure Relief Bi-pass</td>
+<td class="right bot"><a href="#Page_213">213</a></td>
+</tr>
+
+<tr>
+<td class="left top">Oiling System Defects</td>
+<td class="right bot"><a href="#Page_357">357</a></td>
+</tr>
+
+<tr>
+<td class="left top">Oils for Cylinder Lubrication</td>
+<td class="right bot"><a href="#Page_206">206</a></td>
+</tr>
+
+<tr>
+<td class="left top">Oils for Hall-Scott Engine</td>
+<td class="right bot"><a href="#Page_215">215</a></td>
+</tr>
+
+<tr>
+<td class="left top">Oils for Lubrication</td>
+<td class="right bot"><a href="#Page_204">204</a></td>
+</tr>
+
+<tr>
+<td class="left top">Operating Principles of Engines</td>
+<td class="right bot"><a href="#Page_37">37</a></td>
+</tr>
+
+<tr>
+<td class="left top">Oscillating Piston Pin</td>
+<td class="right bot"><a href="#Page_295">295</a></td>
+</tr>
+
+<tr>
+<td class="left top">Otto Four-cycle Cards</td>
+<td class="right bot"><a href="#Page_67">67</a></td>
+</tr>
+
+<tr>
+<td class="left top">Overhauling Aviation Engines</td>
+<td class="right bot"><a href="#Page_412">412</a></td>
+</tr>
+
+<tr>
+<td class="left top">Overhead Cam-shaft Location</td>
+<td class="right bot"><a href="#Page_252">252</a></td>
+</tr>
+
+<tr>
+<td class="left top">Overheating, Causes of</td>
+<td class="right bot"><a href="#Page_359">359</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="center" style="line-height: 2em;"><span class="fsize125">P</span><span
+class='pagenum'><a name="Page_585" id="Page_585">[585]</a></span></td>
+</tr>
+
+<tr>
+<td class="left top">Panhard Concentric Valves</td>
+<td class="right bot"><a href="#Page_255">255</a></td>
+</tr>
+
+<tr>
+<td class="left top">Petroleum, Distillates of</td>
+<td class="right bot"><a href="#Page_111">111</a></td>
+</tr>
+
+<tr>
+<td class="left top">Piston, Differential</td>
+<td class="right bot"><a href="#Page_291">291</a></td>
+</tr>
+
+<tr>
+<td class="left top">Piston Pin Retention</td>
+<td class="right bot"><a href="#Page_293">293</a></td>
+</tr>
+
+<tr>
+<td class="left top">Piston Ring Construction</td>
+<td class="right bot"><a href="#Page_298">298</a></td>
+</tr>
+
+<tr>
+<td class="left top">Piston Ring Joints</td>
+<td class="right bot"><a href="#Page_299">299</a></td>
+</tr>
+
+<tr>
+<td class="left top">Piston Ring Manipulation</td>
+<td class="right bot"><a href="#Page_438">438</a></td>
+</tr>
+
+<tr>
+<td class="left top">Piston Ring Troubles</td>
+<td class="right bot"><a href="#Page_437">437</a></td>
+</tr>
+
+<tr>
+<td class="left top">Piston Rings, Compound</td>
+<td class="right bot"><a href="#Page_301">301</a></td>
+</tr>
+
+<tr>
+<td class="left top">Piston Rings, Concentric</td>
+<td class="right bot"><a href="#Page_299">299</a></td>
+</tr>
+
+<tr>
+<td class="left top">Piston Rings, Eccentric</td>
+<td class="right bot"><a href="#Page_299">299</a></td>
+</tr>
+
+<tr>
+<td class="left top">Piston Rings, Fitting</td>
+<td class="right bot"><a href="#Page_439">439</a></td>
+</tr>
+
+<tr>
+<td class="left top">Piston Rings, Leak Proof</td>
+<td class="right bot"><a href="#Page_301">301</a></td>
+</tr>
+
+<tr>
+<td class="left top">Piston Rings, Replacing</td>
+<td class="right bot"><a href="#Page_441">441</a></td>
+</tr>
+
+<tr>
+<td class="left top">Piston Speed in Airplane Engines</td>
+<td class="right bot"><a href="#Page_241">241</a></td>
+</tr>
+
+<tr>
+<td class="left top">Piston Speed, Meaning of</td>
+<td class="right bot"><a href="#Page_241">241</a></td>
+</tr>
+
+<tr>
+<td class="left top">Piston Troubles and Remedies</td>
+<td class="right bot"><a href="#Page_436">436</a></td>
+</tr>
+
+<tr>
+<td class="left top">Pistons, Aluminum</td>
+<td class="right bot"><a href="#Page_296">296</a></td>
+</tr>
+
+<tr>
+<td class="left top">Pistons, Details of</td>
+<td class="right bot"><a href="#Page_288">288</a></td>
+</tr>
+
+<tr>
+<td class="left top">Pistons for Two-cycle Engines</td>
+<td class="right bot"><a href="#Page_289">289</a></td>
+</tr>
+
+<tr>
+<td class="left top">Positive Valve Systems</td>
+<td class="right bot"><a href="#Page_283">283</a></td>
+</tr>
+
+<tr>
+<td class="left top">Power, Affected by High Altitude</td>
+<td class="right bot"><a href="#Page_145">145</a></td>
+</tr>
+
+<tr>
+<td class="left top">Power Delivery in Multiple Cylinder Engines</td>
+<td class="right bot"><a href="#Page_91">91</a></td>
+</tr>
+
+<tr>
+<td class="left top">Power, How Obtained From Heat</td>
+<td class="right bot"><a href="#Page_58">58</a></td>
+</tr>
+
+<tr>
+<td class="left top">Power Needed in Airplane Engines</td>
+<td class="right bot"><a href="#Page_21">21</a></td>
+</tr>
+
+<tr>
+<td class="left top">Power Used in Airplanes</td>
+<td class="right bot"><a href="#Page_26">26</a></td>
+</tr>
+
+<tr>
+<td class="left top">Precautions in Assembling Parts</td>
+<td class="right bot"><a href="#Page_452">452</a></td>
+</tr>
+
+<tr>
+<td class="left top">Pressure Relief Fitting</td>
+<td class="right bot"><a href="#Page_213">213</a></td>
+</tr>
+
+<tr>
+<td class="left top">Pressures and Temperatures</td>
+<td class="right bot"><a href="#Page_63">63</a></td>
+</tr>
+
+<tr>
+<td class="left top">Principles of Carburetion</td>
+<td class="right bot"><a href="#Page_112">112</a></td>
+</tr>
+
+<tr>
+<td class="left top">Principles of Magneto Action</td>
+<td class="right bot"><a href="#Page_163">163</a></td>
+</tr>
+
+<tr>
+<td class="left top">Properties of Cylinder Oils</td>
+<td class="right bot"><a href="#Page_207">207</a></td>
+</tr>
+
+<tr>
+<td class="left top">Properties of Liquid Fuels</td>
+<td class="right bot"><a href="#Page_110">110</a></td>
+</tr>
+
+<tr>
+<td class="left top">Pump Circulation Systems</td>
+<td class="right bot"><a href="#Page_226">226</a></td>
+</tr>
+
+<tr>
+<td class="left top">Pump Forms</td>
+<td class="right bot"><a href="#Page_226">226</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="center" style="line-height: 2em;"><span class="fsize125">R</span></td>
+</tr>
+
+<tr>
+<td class="left top">Radial Cylinder Arrangement</td>
+<td class="right bot"><a href="#Page_103">103</a></td>
+</tr>
+
+<tr>
+<td class="left top">Reading Indicator Cards</td>
+<td class="right bot"><a href="#Page_67">67</a></td>
+</tr>
+
+<tr>
+<td class="left top">Reamers, Types and Use</td>
+<td class="right bot"><a href="#Page_392">392</a></td>
+</tr>
+
+<tr>
+<td class="left top">Reassembling Parts, Precautions in</td>
+<td class="right bot"><a href="#Page_451">451</a></td>
+</tr>
+
+<tr>
+<td class="left top">Removable Cylinder Head</td>
+<td class="right bot"><a href="#Page_239">239</a></td>
+</tr>
+
+<tr>
+<td class="left top">Renault Air Cooled Engine</td>
+<td class="right bot"><a href="#Page_507">507</a></td>
+</tr>
+
+<tr>
+<td class="left top">Renault Engine Details</td>
+<td class="right bot"><a href="#Page_508">508</a></td>
+</tr>
+
+<tr>
+<td class="left top">Repairing Scored Cylinders</td>
+<td class="right bot"><a href="#Page_423">423</a></td>
+</tr>
+
+<tr>
+<td class="left top">Requisites for Best Power Effect</td>
+<td class="right bot"><a href="#Page_59">59</a></td>
+</tr>
+
+<tr>
+<td class="left top">Reseating and Truing Valves<span class='pagenum'><a name="Page_586" id="Page_586">[586]</a></span></td>
+<td class="right bot"><a href="#Page_426">426</a></td>
+</tr>
+
+<tr>
+<td class="left top">Resistance, Influence of</td>
+<td class="right bot"><a href="#Page_22">22</a></td>
+</tr>
+
+<tr>
+<td class="left top">Rotary Cylinder Engines</td>
+<td class="right bot"><a href="#Page_107">107</a></td>
+</tr>
+
+<tr>
+<td class="left top">Rotary Engine, Le Rhone</td>
+<td class="right bot"><a href="#Page_495">495</a></td>
+</tr>
+
+<tr>
+<td class="left top">Rotary Engines, Castor Oil for</td>
+<td class="right bot"><a href="#Page_211">211</a></td>
+</tr>
+
+<tr>
+<td class="left top">Rotary Engines, Installing</td>
+<td class="right bot"><a href="#Page_342">342</a></td>
+</tr>
+
+<tr>
+<td class="left top">Rotary Engines, Why Odd Number of Cylinders</td>
+<td class="right bot"><a href="#Page_109">109</a></td>
+</tr>
+
+<tr>
+<td class="left top">Rotary Engines, Why Odd Number of Cylinders Is Used</td>
+<td class="right bot"><a href="#Page_482">482</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="center" style="line-height: 2em;"><span class="fsize125">S</span></td>
+</tr>
+
+<tr>
+<td class="left top">S. A. E. Engine Bed Dimensions</td>
+<td class="right bot"><a href="#Page_330">330</a></td>
+</tr>
+
+<tr>
+<td class="left top">Salmson Nine-cylinder Engine</td>
+<td class="right bot"><a href="#Page_470">470</a></td>
+</tr>
+
+<tr>
+<td class="left top">Scissors Joint Rods</td>
+<td class="right bot"><a href="#Page_310">310</a></td>
+</tr>
+
+<tr>
+<td class="left top">Scored Cylinders, Repairing</td>
+<td class="right bot"><a href="#Page_422">422</a></td>
+</tr>
+
+<tr>
+<td class="left top">Scrapers, Types of Bearing</td>
+<td class="right bot"><a href="#Page_446">446</a></td>
+</tr>
+
+<tr>
+<td class="left top">Scraping Bearings to Fit</td>
+<td class="right bot"><a href="#Page_447">447</a></td>
+</tr>
+
+<tr>
+<td class="left top">Second Law of Gases</td>
+<td class="right bot"><a href="#Page_50">50</a></td>
+</tr>
+
+<tr>
+<td class="left top">Sequence of Engine Operation</td>
+<td class="right bot"><a href="#Page_84">84</a></td>
+</tr>
+
+<tr>
+<td class="left top">Shebler Carburetor</td>
+<td class="right bot"><a href="#Page_125">125</a></td>
+</tr>
+
+<tr>
+<td class="left top">Six-cylinder Timing Diagram</td>
+<td class="right bot"><a href="#Page_275">275</a></td>
+</tr>
+
+<tr>
+<td class="left top">Sixteen Valve Duesenberg Engine</td>
+<td class="right bot"><a href="#Page_525">525</a></td>
+</tr>
+
+<tr>
+<td class="left top">Skipping or Irregular Operation, Causes of</td>
+<td class="right bot"><a href="#Page_367">367</a></td>
+</tr>
+
+<tr>
+<td class="left top">Sliding Sleeve Valves</td>
+<td class="right bot"><a href="#Page_266">266</a></td>
+</tr>
+
+<tr>
+<td class="left top">Spark Plug Air Gaps, Setting</td>
+<td class="right bot"><a href="#Page_197">197</a></td>
+</tr>
+
+<tr>
+<td class="left top">Spark Plug, Design of</td>
+<td class="right bot"><a href="#Page_193">193</a></td>
+</tr>
+
+<tr>
+<td class="left top">Spark Plug, Mica</td>
+<td class="right bot"><a href="#Page_194">194</a></td>
+</tr>
+
+<tr>
+<td class="left top">Spark Plug, Porcelain</td>
+<td class="right bot"><a href="#Page_193">193</a></td>
+</tr>
+
+<tr>
+<td class="left top">Spark Plugs, Defects in</td>
+<td class="right bot"><a href="#Page_371">371</a></td>
+</tr>
+
+<tr>
+<td class="left top">Spark Plugs for Two Spark Ignition</td>
+<td class="right bot"><a href="#Page_197">197</a></td>
+</tr>
+
+<tr>
+<td class="left top">Spark Plug, Special for Airplane Engine</td>
+<td class="right bot"><a href="#Page_199">199</a></td>
+</tr>
+
+<tr>
+<td class="left top">Spark Plug, Standard S. A. E.</td>
+<td class="right bot"><a href="#Page_195">195</a></td>
+</tr>
+
+<tr>
+<td class="left top">Spherical Combustion Chambers</td>
+<td class="right bot"><a href="#Page_76">76</a></td>
+</tr>
+
+<tr>
+<td class="left top">Splash Lubrication</td>
+<td class="right bot"><a href="#Page_215">215</a></td>
+</tr>
+
+<tr>
+<td class="left top">Split Pin Remover</td>
+<td class="right bot"><a href="#Page_384">384</a></td>
+</tr>
+
+<tr>
+<td class="left top">Spraying Carburetors</td>
+<td class="right bot"><a href="#Page_120">120</a></td>
+</tr>
+
+<tr>
+<td class="left top">Springless Valves</td>
+<td class="right bot"><a href="#Page_280">280</a></td>
+</tr>
+
+<tr>
+<td class="left top">Springs, for Valves</td>
+<td class="right bot"><a href="#Page_263">263</a></td>
+</tr>
+
+<tr>
+<td class="left top">Spring Winder</td>
+<td class="right bot"><a href="#Page_384">384</a></td>
+</tr>
+
+<tr>
+<td class="left top">Sprung Cam-shaft, Testing</td>
+<td class="right bot"><a href="#Page_451">451</a></td>
+</tr>
+
+<tr>
+<td class="left top">Stand for Supporting Engine</td>
+<td class="right bot"><a href="#Page_414">414</a></td>
+</tr>
+
+<tr>
+<td class="left top">Starting Engine, Hints for</td>
+<td class="right bot"><a href="#Page_361">361</a></td>
+</tr>
+
+<tr>
+<td class="left top">Starting Hall-Scott Engine</td>
+<td class="right bot"><a href="#Page_341">341</a></td>
+</tr>
+
+<tr>
+<td class="left top">Starting System, Christensen</td>
+<td class="right bot"><a href="#Page_567">567</a></td>
+</tr>
+
+<tr>
+<td class="left top">Starting Systems, Compressed Air</td>
+<td class="right bot"><a href="#Page_565">565</a></td>
+</tr>
+
+<tr>
+<td class="left top">Starting Systems, Electric</td>
+<td class="right bot"><a href="#Page_569">569</a></td>
+</tr>
+
+<tr>
+<td class="left top">Statistics, American Engines</td>
+<td class="right bot"><a href="#Page_546">546</a>, <a href="#Page_547">547</a></td>
+</tr>
+
+<tr>
+<td class="left top">Statistic Sheet, Hall-Scott Engines</td>
+<td class="right bot"><a href="#Page_544">544</a></td>
+</tr>
+
+<tr>
+<td class="left top">Statistics of Benz Engine<span class='pagenum'><a name="Page_587" id="Page_587">[587]</a></span></td>
+<td class="right bot"><a href="#Page_551">551</a></td>
+</tr>
+
+<tr>
+<td class="left top">Steam Engine, Efficiency of</td>
+<td class="right bot"><a href="#Page_59">59</a></td>
+</tr>
+
+<tr>
+<td class="left top">Steam Engine, Why Not Used</td>
+<td class="right bot"><a href="#Page_27">27</a></td>
+</tr>
+
+<tr>
+<td class="left top">Steel Scale, Machinists&#8217;</td>
+<td class="right bot"><a href="#Page_399">399</a></td>
+</tr>
+
+<tr>
+<td class="left top">Stewart Metering Pin Carburetor</td>
+<td class="right bot"><a href="#Page_128">128</a></td>
+</tr>
+
+<tr>
+<td class="left top">Storage Battery, Defects in</td>
+<td class="right bot"><a href="#Page_372">372</a></td>
+</tr>
+
+<tr>
+<td class="left top">Stroke and Bore Ratio</td>
+<td class="right bot"><a href="#Page_240">240</a></td>
+</tr>
+
+<tr>
+<td class="left top">Sturtevant Model 5A Engine</td>
+<td class="right bot"><a href="#Page_515">515</a></td>
+</tr>
+
+<tr>
+<td class="left top">Summary of Engine Types</td>
+<td class="right bot"><a href="#Page_30">30</a></td>
+</tr>
+
+<tr>
+<td class="left top">Sunbeam Aviation Engines</td>
+<td class="right bot"><a href="#Page_588">588</a></td>
+</tr>
+
+<tr>
+<td class="left top">Sunbeam Eighteen-Cylinder Engine</td>
+<td class="right bot"><a href="#Page_561">561</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="center" style="line-height: 2em;"><span class="fsize125">T</span></td>
+</tr>
+
+<tr>
+<td class="left top">Tap and Die Sets</td>
+<td class="right bot"><a href="#Page_397">397</a></td>
+</tr>
+
+<tr>
+<td class="left top">Taps for Thread Cutting</td>
+<td class="right bot"><a href="#Page_394">394</a></td>
+</tr>
+
+<tr>
+<td class="left top">Tee Head Cylinders</td>
+<td class="right bot"><a href="#Page_247">247</a></td>
+</tr>
+
+<tr>
+<td class="left top">Temperature Computations</td>
+<td class="right bot"><a href="#Page_52">52</a></td>
+</tr>
+
+<tr>
+<td class="left top">Temperatures and Explosive Pressures</td>
+<td class="right bot"><a href="#Page_64">64</a></td>
+</tr>
+
+<tr>
+<td class="left top">Temperatures and Pressures</td>
+<td class="right bot"><a href="#Page_63">63</a></td>
+</tr>
+
+<tr>
+<td class="left top">Temperatures, Operating</td>
+<td class="right bot"><a href="#Page_221">221</a></td>
+</tr>
+
+<tr>
+<td class="left top">Testing Bearing Parallelism</td>
+<td class="right bot"><a href="#Page_453">453</a></td>
+</tr>
+
+<tr>
+<td class="left top">Testing Connecting Rod Alignment</td>
+<td class="right bot"><a href="#Page_454">454</a></td>
+</tr>
+
+<tr>
+<td class="left top">Testing Fit of Bearings</td>
+<td class="right bot"><a href="#Page_446">446</a></td>
+</tr>
+
+<tr>
+<td class="left top">Testing Sprung Cam-shaft</td>
+<td class="right bot"><a href="#Page_451">451</a></td>
+</tr>
+
+<tr>
+<td class="left top">Theory of Gas Engine</td>
+<td class="right bot"><a href="#Page_47">47</a></td>
+</tr>
+
+<tr>
+<td class="left top">Theory of Lubrication</td>
+<td class="right bot"><a href="#Page_203">203</a></td>
+</tr>
+
+<tr>
+<td class="left top">Thermo-syphon Cooling System</td>
+<td class="right bot"><a href="#Page_227">227</a></td>
+</tr>
+
+<tr>
+<td class="left top">Thomas-Morse Aviation Engine</td>
+<td class="right bot"><a href="#Page_521">521</a></td>
+</tr>
+
+<tr>
+<td class="left top">Thomas-Morse Lubrication System</td>
+<td class="right bot"><a href="#Page_210">210</a></td>
+</tr>
+
+<tr>
+<td class="left top">Thread Pitch Gauge</td>
+<td class="right bot"><a href="#Page_403">403</a></td>
+</tr>
+
+<tr>
+<td class="left top">Time of Ignition</td>
+<td class="right bot"><a href="#Page_273">273</a></td>
+</tr>
+
+<tr>
+<td class="left top">Timer, Defects in</td>
+<td class="right bot"><a href="#Page_373">373</a></td>
+</tr>
+
+<tr>
+<td class="left top">Times of Explosion</td>
+<td class="right bot"><a href="#Page_56">56</a></td>
+</tr>
+
+<tr>
+<td class="left top">Timing Dixie Magneto</td>
+<td class="right bot"><a href="#Page_188">188</a></td>
+</tr>
+
+<tr>
+<td class="left top">Timing Gears, Effects of Wear</td>
+<td class="right bot"><a href="#Page_456">456</a></td>
+</tr>
+
+<tr>
+<td class="left top">Timing Magneto</td>
+<td class="right bot"><a href="#Page_179">179</a></td>
+</tr>
+
+<tr>
+<td class="left top">Timing Valves</td>
+<td class="right bot"><a href="#Page_267">267</a></td>
+</tr>
+
+<tr>
+<td class="left top">Tool Outfits, Typical</td>
+<td class="right bot"><a href="#Page_408">408</a></td>
+</tr>
+
+<tr>
+<td class="left top">Tools for Adjusting and Erecting</td>
+<td class="right bot"><a href="#Page_378">378</a></td>
+</tr>
+
+<tr>
+<td class="left top">Tools for Bearing Work</td>
+<td class="right bot"><a href="#Page_445">445</a></td>
+</tr>
+
+<tr>
+<td class="left top">Tools for Curtiss Engines</td>
+<td class="right bot"><a href="#Page_408">408</a></td>
+</tr>
+
+<tr>
+<td class="left top">Tools for Grinding Valves</td>
+<td class="right bot"><a href="#Page_430">430</a></td>
+</tr>
+
+<tr>
+<td class="left top">Tools for Hall-Scott Engines</td>
+<td class="right bot"><a href="#Page_410">410</a>, <a href="#Page_411">411</a></td>
+</tr>
+
+<tr>
+<td class="left top">Tools for Measuring</td>
+<td class="right bot"><a href="#Page_397">397</a></td>
+</tr>
+
+<tr>
+<td class="left top">Tools for Reseating Valves</td>
+<td class="right bot"><a href="#Page_426">426</a></td>
+</tr>
+
+<tr>
+<td class="left top">Trouble in Carburetion System</td>
+<td class="right bot"><a href="#Page_355">355</a></td>
+</tr>
+
+<tr>
+<td class="left top">Trouble, Location of Magneto</td>
+<td class="right bot"><a href="#Page_181">181</a></td>
+</tr>
+
+<tr>
+<td class="left top">Troubles, Engine, How to Locate<span class='pagenum'><a name="Page_588" id="Page_588">[588]</a></span></td>
+<td class="right bot"><a href="#Page_345">345</a></td>
+</tr>
+
+<tr>
+<td class="left top">Troubles, Ignition</td>
+<td class="right bot"><a href="#Page_353">353</a></td>
+</tr>
+
+<tr>
+<td class="left top">Troubles in Oiling System</td>
+<td class="right bot"><a href="#Page_357">357</a></td>
+</tr>
+
+<tr>
+<td class="left top">True High Tension Magneto</td>
+<td class="right bot"><a href="#Page_172">172</a></td>
+</tr>
+
+<tr>
+<td class="left top">Twelve-Cylinder Engines</td>
+<td class="right bot"><a href="#Page_96">96</a></td>
+</tr>
+
+<tr>
+<td class="left top">Two-and Four-Cycle Types, Comparison of</td>
+<td class="right bot"><a href="#Page_44">44</a></td>
+</tr>
+
+<tr>
+<td class="left top">Two-Cycle Engine Action</td>
+<td class="right bot"><a href="#Page_41">41</a></td>
+</tr>
+
+<tr>
+<td class="left top">Two-Cycle Three-Port Engine</td>
+<td class="right bot"><a href="#Page_43">43</a></td>
+</tr>
+
+<tr>
+<td class="left top">Two-Cycle Two-Port Engine</td>
+<td class="right bot"><a href="#Page_42">42</a></td>
+</tr>
+
+<tr>
+<td class="left top">Two-Spark Ignition</td>
+<td class="right bot"><a href="#Page_196">196</a></td>
+</tr>
+
+<tr>
+<td class="left top">Two-Stage Carburetor</td>
+<td class="right bot"><a href="#Page_131">131</a></td>
+</tr>
+
+<tr>
+<td class="left top">Types of Aircraft</td>
+<td class="right bot"><a href="#Page_17">17</a></td>
+</tr>
+
+<tr>
+<td class="left top">Types of Internal Combustion Engines</td>
+<td class="right bot"><a href="#Page_30">30</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="center" style="line-height: 2em;"><span class="fsize125">V</span></td>
+</tr>
+
+<tr>
+<td class="left top">Vacuum Fuel Feed, Stewart</td>
+<td class="right bot"><a href="#Page_119">119</a></td>
+</tr>
+
+<tr>
+<td class="left top">Value of Compression</td>
+<td class="right bot"><a href="#Page_69">69</a></td>
+</tr>
+
+<tr>
+<td class="left top">Value of Indicator Cards</td>
+<td class="right bot"><a href="#Page_66">66</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valve Actuation, Le Rhone</td>
+<td class="right bot"><a href="#Page_500">500</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valve Design and Construction</td>
+<td class="right bot"><a href="#Page_256">256</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valve-Grinding Processes</td>
+<td class="right bot"><a href="#Page_429">429</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valve-Lifting Cams</td>
+<td class="right bot"><a href="#Page_259">259</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valve-Lifting Plungers</td>
+<td class="right bot"><a href="#Page_260">260</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valve Location Practice</td>
+<td class="right bot"><a href="#Page_245">245</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valve Operating Means</td>
+<td class="right bot"><a href="#Page_252">252</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valve Operating System, Depreciation in</td>
+<td class="right bot"><a href="#Page_433">433</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valve Operation</td>
+<td class="right bot"><a href="#Page_258">258</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valve Removal and Inspection</td>
+<td class="right bot"><a href="#Page_424">424</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valve Seating, How to Test</td>
+<td class="right bot"><a href="#Page_432">432</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valve Springs</td>
+<td class="right bot"><a href="#Page_263">263</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valve Timing, Exhaust</td>
+<td class="right bot"><a href="#Page_270">270</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valve Timing, Gnome Monosoupape</td>
+<td class="right bot"><a href="#Page_278">278</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valve Timing, Intake</td>
+<td class="right bot"><a href="#Page_270">270</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valve Timing, Lag and Lead</td>
+<td class="right bot"><a href="#Page_269">269</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valve Timing Procedure</td>
+<td class="right bot"><a href="#Page_277">277</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valve Timing Practice</td>
+<td class="right bot"><a href="#Page_267">267</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valves, Electric Welded</td>
+<td class="right bot"><a href="#Page_258">258</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valves, Flat and Bevel Seat</td>
+<td class="right bot"><a href="#Page_257">257</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valves, Four per Cylinder</td>
+<td class="right bot"><a href="#Page_284">284</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valves, How Placed in Cylinder</td>
+<td class="right bot"><a href="#Page_247">247</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valves in Cages</td>
+<td class="right bot"><a href="#Page_249">249</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valves in Removable Heads</td>
+<td class="right bot"><a href="#Page_249">249</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valves, Materials Used for</td>
+<td class="right bot"><a href="#Page_258">258</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valves, Reseating</td>
+<td class="right bot"><a href="#Page_426">426</a></td>
+</tr>
+
+<tr>
+<td class="left top">Vaporizer, Simple Forms of</td>
+<td class="right bot"><a href="#Page_120">120</a></td>
+</tr>
+
+<tr>
+<td class="left top">V Engines, Cylinder Arrangement in</td>
+<td class="right bot"><a href="#Page_102">102</a></td>
+</tr>
+
+<tr>
+<td class="left top">Vernier, How Used</td>
+<td class="right bot"><a href="#Page_401">401</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="center" style="line-height: 2em;"><span class="fsize125">W</span><span
+class='pagenum'><a name="Page_589" id="Page_589">[589]</a></span></td>
+</tr>
+
+<tr>
+<td class="left top">Wall Cooling, Losses in</td>
+<td class="right bot"><a href="#Page_65">65</a></td>
+</tr>
+
+<tr>
+<td class="left top">Water Cooling by Natural Circulation</td>
+<td class="right bot"><a href="#Page_227">227</a></td>
+</tr>
+
+<tr>
+<td class="left top">Water Cooling System</td>
+<td class="right bot"><a href="#Page_224">224</a></td>
+</tr>
+
+<tr>
+<td class="left top">Weight of Airplane Motors</td>
+<td class="right bot"><a href="#Page_21">21</a></td>
+</tr>
+
+<tr>
+<td class="left top">Wiring, Defects in</td>
+<td class="right bot"><a href="#Page_373">373</a></td>
+</tr>
+
+<tr>
+<td class="left top">Wiring Magneto Ignition System</td>
+<td class="right bot"><a href="#Page_179">179</a></td>
+</tr>
+
+<tr>
+<td class="left top">Wisconsin Engines</td>
+<td class="right bot"><a href="#Page_531">531</a></td>
+</tr>
+
+<tr>
+<td class="left top">Wrenches, Forms of</td>
+<td class="right bot"><a href="#Page_380">380</a></td>
+</tr>
+
+<tr>
+<td class="left top">Wristpin Retention</td>
+<td class="right bot"><a href="#Page_293">293</a></td>
+</tr>
+
+<tr>
+<td class="left top">Wristpin Retention Locks</td>
+<td class="right bot"><a href="#Page_295">295</a></td>
+</tr>
+
+<tr>
+<td class="left top">Wristpin Wear and Remedy</td>
+<td class="right bot"><a href="#Page_442">442</a></td>
+</tr>
+
+<tr>
+<td colspan="2" class="center" style="line-height: 2em;"><span class="fsize125">Z</span></td>
+</tr>
+
+<tr>
+<td class="left top">Zenith Carburetor, Action of</td>
+<td class="right bot"><a href="#Page_137">137</a></td>
+</tr>
+
+<tr>
+<td class="left top">Zenith Duplex Carburetor, Troubles in</td>
+<td class="right bot"><a href="#Page_356">356</a></td>
+</tr>
+
+<tr>
+<td class="left top">Zenith Carburetor Installation</td>
+<td class="right bot"><a href="#Page_139">139</a></td>
+</tr>
+
+</table>
+
+<hr class="c25" />
+
+<p class='pagenum'><a name="Page_590" id="Page_590"></a></p>
+
+<h2><a name="LoI" id="LoI"></a>LIST OF ILLUSTRATIONS</h2>
+
+<table summary="List of Illustrations">
+
+<tr>
+<td class="top left padr1"><a href="#frontispiece">Frontispiece.</a></td>
+<td class="just">Part Sectional View of Hall-Scott Airplane Motor, Showing Principal Parts.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig001">Fig. 1.</a></td>
+<td class="just">Diagrams Illustrating Computations for Horse-Power Required for Airplane Flight.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig002">Fig. 2.</a></td>
+<td class="just">Plate Showing Heavy, Slow Speed Internal Combustion Engines Used Only for Stationary Power in Large Installations Giving Weight to Horse-Power Ratio.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig003">Fig. 3.</a></td>
+<td class="just">Various Forms of Internal Combustion Engines Showing Decrease in Weight to Horse-Power Ratio with Augmenting Speed of Rotation.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig004">Fig. 4.</a></td>
+<td class="just">Internal Combustion Engine Types of Extremely Fine Construction and Refined Design, Showing Great Power Outputs for Very Small Weight, a Feature Very Much Desired in Airplane Power Plants.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig005">Fig. 5.</a></td>
+<td class="just">Outlining First Two Strokes of Piston in Four-Cycle Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig006">Fig. 6.</a></td>
+<td class="just">Outlining Second Two Strokes of Piston in Four-Cycle Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig007">Fig. 7.</a></td>
+<td class="just">Sectional View of L Head Gasoline Engine Cylinder Showing Piston Movements During Four-Stroke Cycle.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig008">Fig. 8.</a></td>
+<td class="just">Showing Two-port, Two-cycle Engine Operation.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig009">Fig. 9.</a></td>
+<td class="just">Defining Three-port, Two-cycle Engine Action.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig010">Fig. 10.</a></td>
+<td class="just">Diagrams Contrasting Action of Two- and Four-Cycle Cylinders on Exhaust and Intake Stroke.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig011">Fig. 11.</a></td>
+<td class="just">Diagram Isothermal and Adiabatic Lines.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig012">Fig. 12.</a></td>
+<td class="just">Graphic Diagram Showing Approximate Utilization of Fuel Burned in Internal-Combustion Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig013">Fig. 13.</a></td>
+<td class="just">Otto Four-Cycle Card.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig014">Fig. 14.</a></td>
+<td class="just">Diesel Motor Card.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig015">Fig. 15.</a></td>
+<td class="just">Diagram of Heat in the Gas Engine Cylinder.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig016">Fig. 16.</a></td>
+<td class="just">Chart Showing Relation Between Compression Volume and Pressure.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig017">Fig. 17.</a></td>
+<td class="just">The Thompson Indicator, an Instrument for Determining Compressions and Explosion Pressure Values and Recording Them on Chart.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig018">Fig. 18.</a></td>
+<td class="just">Spherical Combustion Chamber.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig019">Fig. 19.</a></td>
+<td class="just">Enlarged Combustion Chamber.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig020">Fig. 20.</a></td>
+<td class="just">Mercedes Aviation Engine Cylinder Section Showing Approximately Spherical Combustion Chamber and Concave Piston Top.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig021">Fig. 21.</a></td>
+<td class="just">Side Sectional View of Typical Airplane Engine, Showing Parts and Their Relation to Each Other. This Engine is an Aeromarine Design and Utilizes a Distinctive Concentric Valve Construction.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig022">Fig. 22.</a></td>
+<td class="just">Diagrams Illustrating Sequence of Cycles in One- and Two-Cylinder Engines Showing More Uniform Turning Effort on Crank-Shaft with Two-Cylinder Motors.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig023">Fig. 23.</a></td>
+<td class="just">Diagrams Demonstrating Clearly Advantages which Obtain when Multiple-Cylinder Motors are Used as Power Plants.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig024">Fig. 24.</a></td>
+<td class="just">Showing Three Possible Though Unconventional Arrangements of Four-Cylinder Engines.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig025">Fig. 25.</a></td>
+<td class="just">Diagrams Outlining Advantages of Multiple Cylinder Motors, and Why They Deliver Power More Evenly Than Single Cylinder Types.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig026">Fig. 26.</a></td>
+<td class="just">Diagrams Showing Duration of Events for a Four-Stroke Cycle, Six-Cylinder Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig027">Fig. 27.</a></td>
+<td class="just">Diagram Showing Actual Duration of Different Strokes in Degrees.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig028">Fig. 28.</a></td>
+<td class="just">Another Diagram to Facilitate Understanding Sequence of Functions in Six-Cylinder Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig029">Fig. 29.</a></td>
+<td class="just">Types of Eight-Cylinder Engines Showing the Advantage of the V Method of Cylinder Placing.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig030">Fig. 30.</a></td>
+<td class="just">Curves Showing Torque of Various Engine Types Demonstrate Graphically Marked Advantage of the Eight-Cylinder Type.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig031">Fig. 31.</a></td>
+<td class="just">Diagrams Showing How Increasing Number of Cylinders Makes for More Uniform Power Application.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig032">Fig. 32.</a></td>
+<td class="just">How the Angle Between the Cylinders of an Eight- and Twelve-Cylinder V Motor Varies.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig033">Fig. 33.</a></td>
+<td class="just">The Hall-Scott Four-Cylinder 100 Horse-Power Aviation Motor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig034">Fig. 34.</a></td>
+<td class="just">Two Views of the Duesenberg Sixteen Valve Four-Cylinder Aviation Motor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig035">Fig. 35.</a></td>
+<td class="just">The Hall-Scott Six-Cylinder Aviation Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig036">Fig. 36.</a></td>
+<td class="just">The Curtiss Eight-Cylinder, 200 Horse-Power Aviation Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig037">Fig. 37.</a></td>
+<td class="just">The Sturtevant Eight-Cylinder, High Speed Aviation Motor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig038">Fig. 38.</a></td>
+<td class="just">Anzani 40-50 Horse-Power Five-Cylinder Air Cooled Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig039">Fig. 39.</a></td>
+<td class="just">Unconventional Six-Cylinder Aircraft Motor of Masson Design.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig040">Fig. 40.</a></td>
+<td class="just">The Gnome Fourteen-Cylinder Revolving Motor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig041">Fig. 41.</a></td>
+<td class="just">How Gravity Feed Fuel Tank May Be Mounted Back of Engine and Secure Short Fuel Line.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig042">Fig. 42.</a></td>
+<td class="just">The Stewart Vacuum Fuel Feed Tank.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig043">Fig. 43.</a></td>
+<td class="just">Marine-Type Mixing Valve, by which Gasoline is Sprayed into Air Stream Through Small Opening in Air-Valve Seat.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig044">Fig. 44.</a></td>
+<td class="just">Tracing Evolution of Modern Spray Carburetor. A&mdash;Early Form Evolved by Maybach. B.&mdash;Ph&oelig;nix-Daimler Modification of Maybach&#8217;s Principle. C&mdash;Modern Concentric Float Automatic Compensating Carburetor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig045">Fig. 45.</a></td>
+<td class="just">New Model of Schebler Carburetor With Metering Valve and Extended Venturi. Note Mechanical Connection Between Air Valve and Fuel Regulating Needle.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig046">Fig. 46.</a></td>
+<td class="just">The Claudel Carburetor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig047">Fig. 47.</a></td>
+<td class="just">The Stewart Metering Pin Carburetor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig048">Fig. 48.</a></td>
+<td class="just">The Ball and Ball Two-Stage Carburetor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig049">Fig. 49.</a></td>
+<td class="just">The Master Carburetor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig050">Fig. 50.</a></td>
+<td class="just">Sectional View of Master Carburetor Showing Parts.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig051">Fig. 51.</a></td>
+<td class="just">Sectional View of Zenith Compound Nozzle Compensating Carburetor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig052">Fig. 52.</a></td>
+<td class="just">Diagrams Explaining Action of Baverey Compound Nozzle Used in Zenith Carburetor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig053">Fig. 53.</a></td>
+<td class="just">The Zenith Duplex Carburetor for Airplane Motors of the V Type.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig054">Fig. 54.</a></td>
+<td class="just">Rear View of Curtiss OX-2 90 Horse-Power Airplane Motor Showing Carburetor Location and Hot Air Leads.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig055">Fig. 55.</a></td>
+<td class="just">Types of Strainers Interposed Between Vaporizer and Gasoline Tank to Prevent Water or Dirt Passing Into Carbureting Device.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig056">Fig. 56.</a></td>
+<td class="just">Chart Showing Diminution of Air Pressure as Altitude Increases.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig057">Fig. 57.</a></td>
+<td class="just">Some Simple Experiments to Demonstrate Various Magnetic Phenomena and Clearly Outline Effects of Magnetism and Various Forms of Magnets.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig058">Fig. 58.</a></td>
+<td class="just">Elementary Form of Magneto Showing Principal Parts Simplified to Make Method of Current Generation Clear.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig059">Fig. 59.</a></td>
+<td class="just">Showing How Strength of Magnetic Influence and of the Currents Induced in the Windings of Armature Vary with the Rapidity of Changes of Flow.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig060">Fig. 60.</a></td>
+<td class="just">Diagrams Explaining Action of Low Tension Transformer Coil and True High Tension Magneto Ignition Systems.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig060a">Fig. 60A.</a></td>
+<td class="just">Side Sectional View of Bosch High-Tension Magneto Shows Disposition of Parts. End Elevation Depicts Arrangement of Interruptor and Distributor Mechanism.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig061">Fig. 61.</a></td>
+<td class="just">Berling Two-Spark Dual Ignition System.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig062">Fig. 62.</a></td>
+<td class="just">Berling Double-Spark Independent System.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig063">Fig. 63.</a></td>
+<td class="just">Type DD Berling High Tension Magneto.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig064">Fig. 64.</a></td>
+<td class="just">Wiring Diagrams of Berling Magneto Ignition Systems.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig065">Fig. 65.</a></td>
+<td class="just">The Berling Magneto Breaker Box Showing Contact Points Separated and Interruptor Lever on Cam.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig066">Fig. 66.</a></td>
+<td class="just">The Dixie Model 60 for Six-Cylinder Airplane Engine Ignition.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig067">Fig. 67.</a></td>
+<td class="just">Installation Dimensions of Dixie Model 60 Magneto.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig068">Fig. 68.</a></td>
+<td class="just">The Rotating Elements of the Dixie Magneto.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig069">Fig. 69.</a></td>
+<td class="just">Suggestions for Adjusting and Dismantling Dixie Magneto. A&mdash;Screw Driver Adjusts Contact Points. B&mdash;Distributor Block Removed. C&mdash;Taking off Magnets. D&mdash;Showing How Easily Condenser and High Tension Windings are Removed.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig069a">Fig. 69A.</a></td>
+<td class="just">Sectional Views Outlining Construction of Dixie Magneto with Compound Distributor for Eight-Cylinder Engine Ignition.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig070">Fig. 70.</a></td>
+<td class="just">Wiring Diagram of Dixie Magneto Installation on Hall-Scott Six-Cylinder 125 Horse-Power Aeronautic Motor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig071">Fig. 71.</a></td>
+<td class="just">How Magneto Ignition is Installed on Thomas-Morse 135 Horse-Power Motor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig072">Fig. 72.</a></td>
+<td class="just">Spark-Plug Types Showing Construction and Arrangement of Parts.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig073">Fig. 73.</a></td>
+<td class="just">Standard Airplane Engine Plug Suggested by S. A. E. Standards Committee.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig074">Fig. 74.</a></td>
+<td class="just">Special Mica Plug for Aviation Engines.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig075">Fig. 75.</a></td>
+<td class="just">Showing Use of Magnifying Glass to Demonstrate that Apparently Smooth Metal Surfaces May Have Minute Irregularities which Produce Friction.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig076">Fig. 76.</a></td>
+<td class="just">Pressure Feed Oiling System of Thomas Aviation Engine Includes Oil Cooling Means.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig077">Fig. 77.</a></td>
+<td class="just">Diagram of Oiling System, Hall-Scott Type A 125 Horse-Power Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig078">Fig. 78.</a></td>
+<td class="just">Sectional View of Typical Motor Showing Parts Needing Lubrication and Method of Applying Oil by Constant Level Splash System. Note also Water Jacket and Spaces for Water Circulation.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig079">Fig. 79.</a></td>
+<td class="just">Pressure Feed Oil-Supply System of Airplane Power Plants has Many Good Features.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig080">Fig. 80.</a></td>
+<td class="just">Why Pressure Feed System is Best for Eight-Cylinder Vee Airplane Engines.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig081">Fig. 81.</a></td>
+<td class="just">Operating Temperatures of Automobile Engine Parts Useful as a Guide to Understand Airplane Power Plant Heat.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig082">Fig. 82.</a></td>
+<td class="just">Water Cooling of Salmson Seven-Cylinder Radial Airplane Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig083">Fig. 83.</a></td>
+<td class="just">How Water Cooling System of Thomas Airplane Engine is Installed in Fuselage.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig084">Fig. 84.</a></td>
+<td class="just">Finned Tube Radiators at the Side of Hall-Scott Airplane Power Plant Installed in Standard Fuselage.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig085">Fig. 85.</a></td>
+<td class="just">Anzani Testing His Five-Cylinder Air Cooled Aviation Motor Installed in Bleriot Monoplane. Note Exposure of Flanged Cylinders to Propeller Slip Stream.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig086">Fig. 86.</a></td>
+<td class="just">Views of Four-Cylinder Duesenberg Airplane Engine Cylinder Block.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig087">Fig. 87.</a></td>
+<td class="just">Twin-Cylinder Block of Sturtevant Airplane Engine is Cast of Aluminum, and Has Removable Cylinder Head.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig088">Fig. 88.</a></td>
+<td class="just">Aluminum Cylinder Pair Casting of Thomas 150 Horse-Power Airplane Engine is of the L Head Type.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig090">Fig. 90.</a></td>
+<td class="just">Cross Section of Austro-Daimler Engine, Showing Offset Cylinder Construction. Note Applied Water Jacket and Peculiar Valve Action.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig091">Fig. 91.</a></td>
+<td class="just">Diagrams Demonstrating Advantages of Offset Crank-Shaft Construction.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig092">Fig. 92.</a></td>
+<td class="just">Diagram Showing Forms of Cylinder Demanded by Different Valve Placings. A&mdash;T Head Type, Valves on Opposite Sides. B&mdash;L Head Cylinder, Valves Side by Side. C&mdash;L Head Cylinder, One Valve in Head, Other in Pocket. D&mdash;Inlet Valve Over Exhaust Member, Both in Side Pocket. E&mdash;Valve-in-the-Head Type with Vertical Valves. F&mdash;Inclined Valves Placed to Open Directly into Combustion Chamber.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig093">Fig. 93.</a></td>
+<td class="just">Sectional View of Engine Cylinder Showing Valve and Cage Installation.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig094">Fig. 94.</a></td>
+<td class="just">Diagrams Showing How Gas Enters Cylinder Through Overhead Valves and Other Types. A&mdash;Tee Head Cylinder. B&mdash;L Head Cylinder. C&mdash;Overhead Valve.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig095">Fig. 95.</a></td>
+<td class="just">Conventional Methods of Operating Internal Combustion Motor Valves.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig096">Fig. 96.</a></td>
+<td class="just">Examples of Direct Valve Actuation by Overhead Cam-Shaft. A&mdash;Mercedes. B&mdash;Hall-Scott. C&mdash;Wisconsin.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig097">Fig. 97.</a></td>
+<td class="just">CENSORED</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig098">Fig. 98.</a></td>
+<td class="just">CENSORED</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig099">Fig. 99.</a></td>
+<td class="just">Sectional Views Showing Arrangement of Novel Concentric Valve Arrangement Devised by Panhard for Aerial Engines.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig100">Fig. 100.</a></td>
+<td class="just">Showing Clearance Allowed Between Valve Stem and Valve Stem Guide to Secure Free Action.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig101">Fig. 101.</a></td>
+<td class="just">Forms of Valve-Lifting Cams Generally Employed. A&mdash;Cam Profile for Long Dwell and Quick Lift. B&mdash;Typical Inlet Cam Used with Mushroom Type Follower. C&mdash;Average Form of Cam. D&mdash;Designed to Give Quick Lift and Gradual Closing.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig102">Fig. 102.</a></td>
+<td class="just">Showing Principal Types of Cam Followers which Have Received General Application.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig103">Fig. 103.</a></td>
+<td class="just">Diagram Showing Proper Clearance to Allow Between Adjusting Screw and Valve Stems in Hall-Scott Aviation Engines.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig104">Fig. 104.</a></td>
+<td class="just">Cam-Shaft of Thomas Airplane Motor Has Cams Forged Integral. Note Split Cam-Shaft Bearings and Method of Gear Retention.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig105">Fig. 105.</a></td>
+<td class="just">Section Through Cylinder of Knight Motor, Showing Important Parts of Valve Motion.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig106">Fig. 106.</a></td>
+<td class="just">Diagrams Showing Knight Sleeve Valve Action.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig107">Fig. 107.</a></td>
+<td class="just">Cross Sectional View of Knight Type Eight Cylinder V Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig108">Fig. 108.</a></td>
+<td class="just">Diagrams Explaining Valve and Ignition Timing of Hall-Scott Aviation Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig109">Fig. 109.</a></td>
+<td class="just">Timing Diagram of Typical Six-Cylinder Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig110">Fig. 110.</a></td>
+<td class="just">Timing Diagram of Typical Eight-Cylinder V Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig111">Fig. 111.</a></td>
+<td class="just">Timing Diagram Showing Peculiar Valve Timing of Gnome &#8220;Monosoupape&#8221; Rotary Motor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig112">Fig. 112.</a></td>
+<td class="just">Two Methods of Operating Valves by Positive Cam Mechanism Which Closes as Well as Opens Them.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig113">Fig. 113.</a></td>
+<td class="just">Diagram Comparing Two Large Valves and Four Small Ones of Practically the Same Area. Note How Easily Small Valves are Installed to Open Directly Into the Cylinder.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig114">Fig. 114.</a></td>
+<td class="just">Sectional Views of Sixteen-Valve Four-Cylinder Automobile Racing Engine That May Have Possibilities for Aviation Service.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig115">Fig. 115.</a></td>
+<td class="just">Front View of Curtiss OX-3 Aviation Motor, Showing Unconventional Valve Action by Concentric Push Rod and Pull Tube.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig116">Fig. 116.</a></td>
+<td class="just">Forms of Pistons Commonly Employed in Gasoline Engines. A&mdash;Dome Head Piston and Three Packing Rings. B&mdash;Flat Top Form Almost Universally Used. C&mdash;Concave Piston Utilized in Knight Motors and Some Having Overhead Valves. D&mdash;Two-Cycle Engine Member with Deflector Plate Cast Integrally. E&mdash;Differential of Two-Diameter Piston Used in Some Engines Operating on Two-Cycle Principle.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig117">Fig. 117.</a></td>
+<td class="just">Typical Methods of Piston Pin Retention Generally Used in Engines of American Design. A&mdash;Single Set Screw and Lock Nut. B&mdash;Set Screw and Check Nut Fitting Groove in Wrist Pin. C, D&mdash;Two Locking Screws Passing Into Interior of Hollow Wrist Pin. E&mdash;Split Ring Holds Pin in Place. F&mdash;Use of Taper Expanding Plugs Outlined. G&mdash;Spring Pressed Plunger Type. H&mdash;Piston Pin Pinned to Connecting Rod. I&mdash;Wrist Pin Clamped in Connecting Rod Small End by Bolt.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig118">Fig. 118.</a></td>
+<td class="just">Typical Piston and Connecting Rod Assembly.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig119">Fig. 119.</a></td>
+<td class="just">Parts of Sturtevant Aviation Engine. A&mdash;Cylinder Head Showing Valves. B&mdash;Connecting Rod. C&mdash;Piston and Rings.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig120">Fig. 120.</a></td>
+<td class="just">Aluminum Piston and Light But Strong Steel Connecting Rod and Wrist Pin of Thomas Aviation Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig121">Fig. 121.</a></td>
+<td class="just">Cast Iron Piston of &#8220;Monosoupape&#8221; Gnome Engine Installed On One of the Short Connecting Rods.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig122">Fig. 122.</a></td>
+<td class="just">Types of Aluminum Pistons Used In Aviation Engines.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig123">Fig. 123.</a></td>
+<td class="just">Types of Piston Rings and Ring Joints. A&mdash;Concentric Ring. B&mdash;Eccentrically Machined Form. C&mdash;Lap Joint Ring. D&mdash;Butt Joint, Seldom Used. E&mdash;Diagonal Cut Member, a Popular Form.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig124">Fig. 124.</a></td>
+<td class="just">Diagrams Showing Advantages of Concentric Piston Rings.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig125">Fig. 125.</a></td>
+<td class="just">Leak-Proof and Other Compound Piston Rings.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig126">Fig. 126.</a></td>
+<td class="just">Sectional View of Engine Showing Means of Preventing Oil Leakage By Piston Rings.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig127">Fig. 127.</a></td>
+<td class="just">Connecting Rod and Crank-Shaft Construction of Gnome &#8220;Monosoupape&#8221; Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig128">Fig. 128.</a></td>
+<td class="just">Connecting Rod Types Summarized. A&mdash;Single Connecting Rod Made in One Piece, Usually Fitted in Small Single-Cylinder Engines Having Built-Up Crank-Shafts. B&mdash;Marine Type, a Popular Form on Heavy Engines. C&mdash;Conventional Automobile Type, a Modified Marine Form. D&mdash;Type Having Hinged Lower Cap and Split Wrist Pin Bushing. E&mdash;Connecting Rod Having Diagonally Divided Big End. F&mdash;Ball-Bearing Rod. G&mdash;Sections Showing Structural Shapes Commonly Employed in Connecting Rod Construction.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig129">Fig. 129.</a></td>
+<td class="just">Double Connecting Rod Assembly For Use On Single Crank-Pin of Vee Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig130">Fig. 130.</a></td>
+<td class="just">Another Type of Double Connecting Rod for Vee Engines.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig131">Fig. 131.</a></td>
+<td class="just">Part Sectional View of Wisconsin Aviation Engine, Showing Four-Bearing Crank-Shaft, Overhead Cam-Shaft, and Method of Combining Cylinders in Pairs.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig132">Fig. 132.</a></td>
+<td class="just">Part Sectional View of Renault Twelve-Cylinder Water-Cooled Engine, Showing Connecting Rod Construction and Other Important Internal Parts.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig133">Fig. 133.</a></td>
+<td class="just">Typical Cam-Shaft, with Valve Lifting Cams and Gears to Operate Auxiliary Devices Forged Integrally.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig134">Fig. 134.</a></td>
+<td class="just">Important Parts of Duesenberg Aviation Engine. A&mdash;Three Main Bearing Crank-Shaft. B&mdash;Cam-Shaft with Integral Cams. C&mdash;Piston and Connecting Rod Assembly. D&mdash;Valve Rocker Group. E&mdash;Piston. F&mdash;Main Bearing Brasses.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig135">Fig. 135.</a></td>
+<td class="just">Showing Method of Making Crank-Shaft. A&mdash;The Rough Steel Forging Before Machining. B&mdash;The Finished Six-Throw, Seven-Bearing Crank-Shaft.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig136">Fig. 136.</a></td>
+<td class="just">Showing Form of Crank-Shaft for Twin-Cylinder Opposed Power Plant.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig137">Fig. 137.</a></td>
+<td class="just">Crank-Shaft of Thomas-Morse Eight-Cylinder Vee Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig138">Fig. 138.</a></td>
+<td class="just">Crank-Case and Crank-Shaft Construction for Twelve-Cylinder Motors. A&mdash;Duesenberg. B&mdash;Curtiss.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig139">Fig. 139.</a></td>
+<td class="just">Counterbalanced Crank-Shafts Reduce Engine Vibration and Permit of Higher Rotative Speeds.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig140">Fig. 140.</a></td>
+<td class="just">View of Thomas 135 Horse-Power Aeromotor, Model 8, Showing Conventional Method of Crank-Case Construction.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig141">Fig. 141.</a></td>
+<td class="just">Views of Upper Half of Thomas Aeromotor Crank-Case.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig142">Fig. 142.</a></td>
+<td class="just">Method of Constructing Eight-Cylinder Vee Engine, Possible if Aluminum Cylinder and Crank-Case Castings are Used.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig143">Fig. 143.</a></td>
+<td class="just">Simple and Compact Crank-Case, Possible When Radial Cylinder Engine Design is Followed.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig144">Fig. 144.</a></td>
+<td class="just">Unconventional Mounting of German Inverted Cylinder Motor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig145">Fig. 145.</a></td>
+<td class="just">How Curtiss Model OX-2 Motor is Installed in Fuselage of Curtiss Tractor Biplane. Note Similarity of Mounting to Automobile Power Plant.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig146">Fig. 146.</a></td>
+<td class="just">Latest Model of Curtiss JN-4 Training Machine, Showing Thorough Enclosure of Power Plant and Method of Disposing of the Exhaust Gases.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig147">Fig. 147.</a></td>
+<td class="just">Front View of L. W. F. Tractor Biplane Fuselage, Showing Method of Installing Thomas Aeromotor and Method of Disposing of Exhaust Gases.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig148">Fig. 148.</a></td>
+<td class="just">End Elevation of Hall-Scott A-7 Four-Cylinder Motor, with Installation Dimensions.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig149">Fig. 149.</a></td>
+<td class="just">Plan and Side Elevation of Hall-Scott A-7 Four-Cylinder Airplane Engine, with Installation Dimensions.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig150">Fig. 150.</a></td>
+<td class="just">CENSORED</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig151">Fig. 151.</a></td>
+<td class="just">CENSORED</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig152">Fig. 152.</a></td>
+<td class="just">CENSORED</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig153">Fig. 153.</a></td>
+<td class="just">Plan View of Hall-Scott Type A-5 125 Horse-Power Airplane Engine, Showing Installation Dimensions.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig154">Fig. 154.</a></td>
+<td class="just">Three-Quarter View of Hall-Scott Type A-5 125 Horse-Power Six-Cylinder Engine, with One of the Side Radiators Removed to Show Installation in Standard Fuselage.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig155">Fig. 155.</a></td>
+<td class="just">Diagram Showing Proper Installation of Hall-Scott Type A-5 125 Horse-Power Engine with Pressure Feed Fuel Supply System.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig156">Fig. 156.</a></td>
+<td class="just">Diagram Defining Installation of Gnome &#8220;Monosoupape&#8221; Motor in Tractor Biplane. Note Necessary Piping for Fuel, Oil, and Air Lines.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig157">Fig. 157.</a></td>
+<td class="just">Showing Two Methods of Placing Propeller on Gnome Rotary Motor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig158">Fig. 158.</a></td>
+<td class="just">How Gnome Rotary Motor May Be Attached to Airplane Fuselage Members.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig159">Fig. 159.</a></td>
+<td class="just">How Anzani Ten-Cylinder Radial Engine is Installed to Plate Securely Attached to Front End of Tractor Airplane Fuselage.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig160">Fig. 160.</a></td>
+<td class="just">Side Elevation of Thomas 135 Horse-Power Airplane Engine, Giving Important Dimensions.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig161">Fig. 161.</a></td>
+<td class="just">Front Elevation of Thomas-Morse 135 Horse-Power Aeromotor, Showing Main Dimensions.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig162">Fig. 162.</a></td>
+<td class="just">Front and Side Elevations of Sturtevant Airplane Engine, Giving Principal Dimensions to Facilitate Installation.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig163">Fig. 163.</a></td>
+<td class="just">Practical Hand Tools Useful in Dismantling and Repairing Airplane Engines.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig164">Fig. 164.</a></td>
+<td class="just">Wrenches are Offered in Many Forms.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig165">Fig. 165.</a></td>
+<td class="just">Illustrating Use and Care of Files.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig166">Fig. 166.</a></td>
+<td class="just">Outlining Use of Cotter Pin Pliers, Spring Winder, and Showing Practical Outfit of Chisels.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig167">Fig. 167.</a></td>
+<td class="just">Forms of Hand Operated Drilling Machines.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig168">Fig. 168.</a></td>
+<td class="just">Forms of Drills Used in Hand and Power Drilling Machines.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig169">Fig. 169.</a></td>
+<td class="just">Useful Set of Number Drills, Showing Stand for Keeping These in an Orderly Manner.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig170">Fig. 170.</a></td>
+<td class="just">Illustrating Standard Forms of Hand and Machine Reamers.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig171">Fig. 171.</a></td>
+<td class="just">Tools for Thread Cutting.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig172">Fig. 172.</a></td>
+<td class="just">Showing Holder Designs for One- and Two-Piece Thread Cutting Dies.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig173">Fig. 173.</a></td>
+<td class="just">Useful Outfit of Taps and Dies for the Engine Repair Shop.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig174">Fig. 174.</a></td>
+<td class="just">Common Forms of Inside and Outside Calipers.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig175">Fig. 175.</a></td>
+<td class="just">Measuring Appliances for the Machinist and Floor Man.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig176">Fig. 176.</a></td>
+<td class="just">At Left, Special Form of Vernier Caliper for Measuring Gear Teeth; at Right, Micrometer for Accurate Internal Measurements.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig177">Fig. 177.</a></td>
+<td class="just">Measuring Appliances of Value in Airplane Repair Work.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig178">Fig. 178.</a></td>
+<td class="just">Standard Forms of Micrometer Caliper for External Measurements.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig179">Fig. 179.</a></td>
+<td class="just">Special Tools for Maintaining Curtiss OX-2 Motor Used in Curtiss JN-4 Training Biplane.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig180">Fig. 180.</a></td>
+<td class="just">Special Tools and Appliances to Facilitate Overhauling Work on Hall-Scott Airplane Engines.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig181">Fig. 181.</a></td>
+<td class="just">Special Stand to Make Motor Overhauling Work Easier.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig182">Fig. 182.</a></td>
+<td class="just">Showing Where Carbon Deposits Collect in Engine Combustion Chamber, and How to Burn Them Out with the Aid of Oxygen. A&mdash;Special Torch. B&mdash;Torch Coupled to Oxygen Tank. C&mdash;Torch in Use.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig182a">Fig. 182<sup>1</sup>&#8260;<sub>2</sub>.</a></td>
+<td class="just">Part Sectional View, Showing Valve Arrangement in Cylinder of Curtiss OX-2 Aviation Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig183">Fig. 183.</a></td>
+<td class="just">Tools for Restoring Valve Head and Seats.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig184">Fig. 184.</a></td>
+<td class="just">Tools and Processes Utilized in Valve Grinding.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig185">Fig. 185.</a></td>
+<td class="just">Outlining Points in Valve Operating Mechanism Where Depreciation is Apt to Exist.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig186">Fig. 186.</a></td>
+<td class="just">Method of Removing Piston Rings, and Simple Clamp to Facilitate Insertion of Rings in Cylinder.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig187">Fig. 187.</a></td>
+<td class="just">Tools and Processes Used in Refitting Engine Bearings.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig188">Fig. 188.</a></td>
+<td class="just">Showing Points to Observe When Fitting Connecting Rod Brasses.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig189">Fig. 189.</a></td>
+<td class="just">Methods of Testing to Insure Parallelism of Bearings After Fitting.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig190">Fig. 190.</a></td>
+<td class="just">Views Outlining Construction of Three-Cylinder Anzani Aviation Motor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig190a">Fig. 190a.</a></td>
+<td class="just">Illustrations Depicting Wrong and Right Methods of &#8220;Swinging the Stick&#8221; to Start Airplane Engine. At Top, Poor Position to Get Full Throw and Get Out of the Way. Below, Correct Position to Get Quick Turn Over of Crank-Shaft and Spring Away from Propeller.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig191">Fig. 191.</a></td>
+<td class="just">The Anzani Six-Cylinder Water-Cooled Aviation Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig192">Fig. 192.</a></td>
+<td class="just">Sectional View of Anzani Six-Cylinder Water-Cooled Aviation Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig193">Fig. 193.</a></td>
+<td class="just">Three-Cylinder Anzani Air-Cooled Y-Form Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig194">Fig. 194.</a></td>
+<td class="just">Anzani Fixed Crank-Case Engine of the Six-Cylinder Form Utilizes Air Cooling Successfully.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig195">Fig. 195.</a></td>
+<td class="just">Sectional View Showing Internal Parts of Six-Cylinder Anzani Engine, with Starwise Disposition of Cylinders.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig196">Fig. 196.</a></td>
+<td class="just">The Anzani Ten-Cylinder Aviation Engine at the Left, and the Twenty-Cylinder Fixed Type at the Right.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig197">Fig. 197.</a></td>
+<td class="just">Application of R. E. P. Five-Cylinder Fan-Shape Air-Cooled Motor to Early Monoplane.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig198">Fig. 198.</a></td>
+<td class="just">The Canton and Unn&eacute; Nine-Cylinder Water-Cooled Radial Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig199">Fig. 199.</a></td>
+<td class="just">Sectional View Showing Construction of Canton and Unn&eacute; Water-Cooled Radial Cylinder Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig200">Fig. 200.</a></td>
+<td class="just">Sectional View Outlining Construction of Early Type Gnome Valve-in-Piston Type Motor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig201">Fig. 201.</a></td>
+<td class="just">Sectional View of Early Type Gnome Cylinder and Piston Showing Construction and Application of Inlet and Exhaust Valves.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig202">Fig. 202.</a></td>
+<td class="just">Details of Old Style Gnome Motor Inlet and Exhaust Valve Construction and Operation.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig203">Fig. 203.</a></td>
+<td class="just">The Gnome Fourteen-Cylinder 100 Horse-Power Aviation Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig204">Fig. 204.</a></td>
+<td class="just">Cam and Cam-Gear Case of the Gnome Seven-Cylinder Revolving Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig205">Fig. 205.</a></td>
+<td class="just">Diagrams Showing Why An Odd Number of Cylinders is Best for Rotary Cylinder Motors.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig206">Fig. 206.</a></td>
+<td class="just">Simple Carburetor Used On Early Gnome Engines Attached to Fixed Crank-Shaft End.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig207">Fig. 207.</a></td>
+<td class="just">Sectional Views of the Gnome Oil Pump.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig208">Fig. 208.</a></td>
+<td class="just">Simplified Diagram Showing Gnome Motor Magneto Ignition System.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig209">Fig. 209.</a></td>
+<td class="just">The G. V. Gnome &#8220;Monosoupape&#8221; Nine-Cylinder Rotary Engine Mounted on Testing Stand.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig210">Fig. 210.</a></td>
+<td class="just">Sectional View Showing Construction of General Vehicle Co. &#8220;Monosoupape&#8221; Gnome Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig211">Fig. 211.</a></td>
+<td class="just">How a Gnome Cylinder is Reduced from Solid Chunk of Steel Weighing 97 Pounds to Finished Cylinder Weighing 5<sup>1</sup>&#8260;<sub>2</sub> Pounds.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig212">Fig. 212.</a></td>
+<td class="just">The Gnome Engine Cam-Gear Case, a Fine Example of Accurate Machine Work.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig213">Fig. 213.</a></td>
+<td class="just">G. V. Gnome &#8220;Monosoupape,&#8221; with Cam-Case Cover Removed to Show Cams and Valve-Operating Plungers with Roller Cam Followers.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig214">Fig. 214.</a></td>
+<td class="just">The 50 Horse-Power Rotary Bayerischen Motoren Gesellschaft Engine, a German Adaptation of the Early Gnome Design.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig215">Fig. 215.</a></td>
+<td class="just">Nine-Cylinder Revolving Le Rhone Type Aviation Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig216">Fig. 216.</a></td>
+<td class="just">Part Sectional Views of Le Rhone Rotary Cylinder Engine, Showing Method of Cylinder Retention, Valve Operation and Novel Crank Disc Assembly.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig217">Fig. 217.</a></td>
+<td class="just">Side Sectional View of Le Rhone Aviation Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig218">Fig. 218.</a></td>
+<td class="just">View Showing Le Rhone Valve Action and Connecting Rod Big End Arrangement.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig219">Fig. 219.</a></td>
+<td class="just">Diagrams Showing Important Components of Le Rhone Motor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig220">Fig. 220.</a></td>
+<td class="just">How the Cams of the Le Rhone Motor Can Operate Two Valves with a Single Push Rod.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig221">Fig. 221.</a></td>
+<td class="just">The Le Rhone Carburetor at A and Fuel Supply Regulating Device at B.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig222">Fig. 222.</a></td>
+<td class="just">Diagrams Showing Le Rhone Motor Action and Firing Order.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig223">Fig. 223.</a></td>
+<td class="just">Diagram Showing Positions of Piston in Le Rhone Rotary Cylinder Motor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig224">Fig. 224.</a></td>
+<td class="just">Diagrams Showing Valve Timing of Le Rhone Aviation Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig225">Fig. 225.</a></td>
+<td class="just">Diagrams Showing How Cylinder Cooling is Effected in Renault Vee Engines.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig226">Fig. 226.</a></td>
+<td class="just">End Sectional View of Renault Air-Cooled Aviation Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig227">Fig. 227.</a></td>
+<td class="just">Side Sectional View of Renault Twelve-Cylinder Air-Cooled Aviation Engine Crank-Case, Showing Use of Plain and Ball Bearings for Crank-Shaft Support.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig228">Fig. 228.</a></td>
+<td class="just">End View of Renault Twelve-Cylinder Engine Crank-Case, Showing Magneto Mounting.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig229">Fig. 229.</a></td>
+<td class="just">Diagram Outlining Renault Twelve-Cylinder Engine Ignition System.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig230">Fig. 230.</a></td>
+<td class="just">The Simplex Model A Hispano-Suiza Aviation Engine, a Very Successful Form.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig231">Fig. 231.</a></td>
+<td class="just">The Curtiss OXX-5 Aviation Engine is an Eight-Cylinder Type Largely Used on Training Machines.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig232">Fig. 232.</a></td>
+<td class="just">Top and Bottom Views of the Curtiss OXX-5 100 Horse-Power Aviation Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig233">Fig. 233.</a></td>
+<td class="just">End View of Thomas-Morse 150 Horse-Power Aluminum Cylinder Aviation Motor Having Detachable Cylinder Heads.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig234">Fig. 234.</a></td>
+<td class="just">Side View of Thomas-Morse High Speed 150 Horse-Power Aviation Motor with Geared Down Propeller Drive.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig235">Fig. 235.</a></td>
+<td class="just">The Reduction Gear-Case of Thomas-Morse 150 Horse-Power Aviation Motor, Showing Ball Bearing and Propeller Drive Shaft Gear.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig236">Fig. 236.</a></td>
+<td class="just">The Six-Cylinder Aeromarine Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig237">Fig. 237.</a></td>
+<td class="just">The Wisconsin Aviation Engine, at Top, as Viewed from Carburetor Side. Below, the Exhaust Side.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig238">Fig. 238.</a></td>
+<td class="just">Dimensioned End Elevation of Wisconsin Six Motor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig239">Fig. 239.</a></td>
+<td class="just">Dimensioned Side Elevation of Wisconsin Six Motor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig240">Fig. 240.</a></td>
+<td class="just">Power, Torque and Efficiency Curves of Wisconsin Aviation Motor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig241">Fig. 241.</a></td>
+<td class="just">Timing Diagram, Wisconsin Aviation Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig242">Fig. 242.</a></td>
+<td class="just">Dimensioned End View of Wisconsin Twelve-Cylinder Airplane Motor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig243">Fig. 243.</a></td>
+<td class="just">Dimensioned Side Elevation of Wisconsin Twelve-Cylinder Airplane Motor.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig244">Fig. 244.</a></td>
+<td class="just">Side and End Sectional Views of Four-Cylinder Argus Engine, a German 100 Horse-Power Design Having Bore and Stroke of 140 mm., or 5.60 inches, and Developing Its Power at 1,368 R.P.M. Weight, 350 Pounds.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig245">Fig. 245.</a></td>
+<td class="just">Part Sectional View of 90 Horse-Power Mercedes Engine, Which is Typical of the Design of Larger Sizes.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig246">Fig. 246.</a></td>
+<td class="just">Part Sectional Side View and Sectional End View of Benz 160 Horse-Power Aviation Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig247">Fig. 247.</a></td>
+<td class="just">At Top, the Sunbeam Overhead Valve 170 Horse-Power Six-Cylinder Engine. Below, Side View of Sunbeam 350 Horse-Power Twelve-Cylinder Vee Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig248">Fig. 248.</a></td>
+<td class="just">Side View of Eighteen-Cylinder Sunbeam Coatalen Aircraft Engine Rated at 475 B.H.P.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig249">Fig. 249.</a></td>
+<td class="just">Sunbeam Eighteen-Cylinder Motor, Viewed from Pump and Magneto End.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig250">Fig. 250.</a></td>
+<td class="just">Propeller End of Sunbeam Eighteen-Cylinder 475 B.H.P. Aviation Engine.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig251">Fig. 251.</a></td>
+<td class="just">View of Airplane Cowl Board, Showing the Various Navigating and Indicating Instruments to Aid the Aviator in Flight.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig252">Fig. 252.</a></td>
+<td class="just">Parts of Christensen Air Starting System Shown at A, and Application of Piping and Check Valves to Cylinders of Thomas-Morse Aeromotor Outlined at B.</td>
+</tr>
+
+<tr>
+<td class="top left"><a href="#Fig253">Fig. 253.</a></td>
+<td class="just">Diagrams Showing Installation of Air Starting System on Thomas-Morse Aviation Motor.</td>
+</tr>
+
+</table>
+
+<hr class="c25" />
+<p class='pagenum'><a name="Page_Cat1" id="Page_Cat1"></a></p>
+
+<div class="boxoutside"><div class="boxinside">
+<h2 class="gesp fsize175" style="margin: 1em auto;">CATALOGUE</h2>
+
+<p class="center" style="margin: 1.5em auto;"><i>Of the</i> LATEST <i>and</i> BEST</p>
+
+<p class="center fsize125">PRACTICAL <i>and</i> MECHANICAL</p>
+
+<p class="center fsize175"><b>BOOKS</b></p>
+
+<p class="center"><i>Including Automobile and Aviation Books</i></p>
+
+<div class="figcenter">
+<img src="images/illo004.png" alt="The bright light of science" width="100" height="82" />
+</div>
+
+<p class="fsize80 center" style="margin: 2.5em 20%;"><i>Any of these books will be sent prepaid to any part of the world,
+on receipt of price. Remit by Draft, Postal Order, Express
+Order or Registered Letter</i></p>
+
+<hr class="c05" />
+
+<p class="center" style="margin-top: 1.5em;"><span class="fsize80">Published and For Sale By</span><br />
+<span class="fsize125"><b>The Norman W. Henley Publishing Co.,</b></span><br />
+2 West 45th Street, New York, U.S.A.</p>
+</div></div>
+
+<p class='pagenum'><a name="Page_Cat2" id="Page_Cat2">[2]</a></p>
+
+<h2>INDEX</h2>
+
+<table summary="Index Catalogue">
+
+<tr>
+<td colspan="2" class="right">PAGES</td>
+</tr>
+
+<tr>
+<td class="left top">Air Brakes</td>
+<td class="right bot"><a href="#Page_Cat21">21</a>, <a href="#Page_Cat24">24</a></td>
+</tr>
+
+<tr>
+<td class="left top">Arithmetic</td>
+<td class="right bot"><a href="#Page_Cat14">14</a>, <a href="#Page_Cat25">25</a>, <a href="#Page_Cat31">31</a></td>
+</tr>
+
+<tr>
+<td class="left top">Automobile Books</td>
+<td class="right bot"><a href="#Page_Cat3">3</a>, <a href="#Page_Cat4">4</a>, <a href="#Page_Cat5">5</a>, <a href="#Page_Cat6">6</a></td>
+</tr>
+
+<tr>
+<td class="left top">Automobile Charts</td>
+<td class="right bot"><a href="#Page_Cat6">6</a>, <a href="#Page_Cat7">7</a></td>
+</tr>
+
+<tr>
+<td class="left top">Automobile Ignition Systems</td>
+<td class="right bot"><a href="#Page_Cat5">5</a></td>
+</tr>
+
+<tr>
+<td class="left top">Automobile Lighting</td>
+<td class="right bot"><a href="#Page_Cat5">5</a></td>
+</tr>
+
+<tr>
+<td class="left top">Automobile Questions and Answers</td>
+<td class="right bot"><a href="#Page_Cat4">4</a></td>
+</tr>
+
+<tr>
+<td class="left top">Automobile Repairing</td>
+<td class="right bot"><a href="#Page_Cat4">4</a></td>
+</tr>
+
+<tr>
+<td class="left top">Automobile Starting Systems</td>
+<td class="right bot"><a href="#Page_Cat5">5</a></td>
+</tr>
+
+<tr>
+<td class="left top">Automobile Trouble Charts</td>
+<td class="right bot"><a href="#Page_Cat5">5</a>, <a href="#Page_Cat6">6</a></td>
+</tr>
+
+<tr>
+<td class="left top">Automobile Welding</td>
+<td class="right bot"><a href="#Page_Cat5">5</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation</td>
+<td class="right bot"><a href="#Page_Cat7">7</a></td>
+</tr>
+
+<tr>
+<td class="left top">Aviation Chart</td>
+<td class="right bot"><a href="#Page_Cat7">7</a></td>
+</tr>
+
+<tr>
+<td class="left top">Batteries, Storage</td>
+<td class="right bot"><a href="#Page_Cat5">5</a></td>
+</tr>
+
+<tr>
+<td class="left top">Bevel Gear</td>
+<td class="right bot"><a href="#Page_Cat19">19</a></td>
+</tr>
+
+<tr>
+<td class="left top">Boiler-Room Chart</td>
+<td class="right bot"><a href="#Page_Cat9">9</a></td>
+</tr>
+
+<tr>
+<td class="left top">Brazing</td>
+<td class="right bot"><a href="#Page_Cat7">7</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cams</td>
+<td class="right bot"><a href="#Page_Cat19">19</a></td>
+</tr>
+
+<tr>
+<td class="left top">Carburetion Trouble Chart</td>
+<td class="right bot"><a href="#Page_Cat6">6</a></td>
+</tr>
+
+<tr>
+<td class="left top">Change Gear</td>
+<td class="right bot"><a href="#Page_Cat19">19</a></td>
+</tr>
+
+<tr>
+<td class="left top">Charts</td>
+<td class="right bot"><a href="#Page_Cat6">6</a>, <a href="#Page_Cat7">7</a>, <a href="#Page_Cat8">8</a></td>
+</tr>
+
+<tr>
+<td class="left top">Coal</td>
+<td class="right bot"><a href="#Page_Cat22">22</a></td>
+</tr>
+
+<tr>
+<td class="left top">Coke</td>
+<td class="right bot"><a href="#Page_Cat9">9</a></td>
+</tr>
+
+<tr>
+<td class="left top">Combustion</td>
+<td class="right bot"><a href="#Page_Cat22">22</a></td>
+</tr>
+
+<tr>
+<td class="left top">Compressed Air</td>
+<td class="right bot"><a href="#Page_Cat10">10</a></td>
+</tr>
+
+<tr>
+<td class="left top">Concrete</td>
+<td class="right bot"><a href="#Page_Cat10">10</a>, <a href="#Page_Cat11">11</a>, <a href="#Page_Cat12">12</a></td>
+</tr>
+
+<tr>
+<td class="left top">Concrete for Farm Use</td>
+<td class="right bot"><a href="#Page_Cat11">11</a></td>
+</tr>
+
+<tr>
+<td class="left top">Concrete for Shop Use</td>
+<td class="right bot"><a href="#Page_Cat11">11</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cosmetics</td>
+<td class="right bot"><a href="#Page_Cat27">27</a></td>
+</tr>
+
+<tr>
+<td class="left top">Cyclecars</td>
+<td class="right bot"><a href="#Page_Cat5">5</a></td>
+</tr>
+
+<tr>
+<td class="left top">Dictionary</td>
+<td class="right bot"><a href="#Page_Cat12">12</a></td>
+</tr>
+
+<tr>
+<td class="left top">Dies</td>
+<td class="right bot"><a href="#Page_Cat12">12</a>, <a href="#Page_Cat13">13</a></td>
+</tr>
+
+<tr>
+<td class="left top">Drawing</td>
+<td class="right bot"><a href="#Page_Cat13">13</a>, <a href="#Page_Cat14">14</a></td>
+</tr>
+
+<tr>
+<td class="left top">Drawing for Plumbers</td>
+<td class="right bot"><a href="#Page_Cat28">28</a></td>
+</tr>
+
+<tr>
+<td class="left top">Drop Forging</td>
+<td class="right bot"><a href="#Page_Cat13">13</a></td>
+</tr>
+
+<tr>
+<td class="left top">Dynamo Building</td>
+<td class="right bot"><a href="#Page_Cat14">14</a></td>
+</tr>
+
+<tr>
+<td class="left top">Electric Bells</td>
+<td class="right bot"><a href="#Page_Cat14">14</a></td>
+</tr>
+
+<tr>
+<td class="left top">Electric Switchboards</td>
+<td class="right bot"><a href="#Page_Cat14">14</a>, <a href="#Page_Cat16">16</a></td>
+</tr>
+
+<tr>
+<td class="left top">Electric Toy Making</td>
+<td class="right bot"><a href="#Page_Cat15">15</a></td>
+</tr>
+
+<tr>
+<td class="left top">Electric Wiring</td>
+<td class="right bot"><a href="#Page_Cat14">14</a>, <a href="#Page_Cat15">15</a>, <a href="#Page_Cat16">16</a></td>
+</tr>
+
+<tr>
+<td class="left top">Electricity</td>
+<td class="right bot"><a href="#Page_Cat14">14</a>, <a href="#Page_Cat15">15</a>, <a href="#Page_Cat16">16</a>,
+<a href="#Page_Cat17">17</a></td>
+</tr>
+
+<tr>
+<td class="left top">Encyclopedia</td>
+<td class="right bot"><a href="#Page_Cat24">24</a></td>
+</tr>
+
+<tr>
+<td class="left top">E-T Air Brake</td>
+<td class="right bot"><a href="#Page_Cat24">24</a></td>
+</tr>
+
+<tr>
+<td class="left top">Every-day Engineering</td>
+<td class="right bot"><a href="#Page_Cat34">34</a></td>
+</tr>
+
+<tr>
+<td class="left top">Factory Management</td>
+<td class="right bot"><a href="#Page_Cat17">17</a></td>
+</tr>
+
+<tr>
+<td class="left top">Ford Automobile</td>
+<td class="right bot"><a href="#Page_Cat3">3</a></td>
+</tr>
+
+<tr>
+<td class="left top">Ford Trouble Chart</td>
+<td class="right bot"><a href="#Page_Cat6">6</a></td>
+</tr>
+
+<tr>
+<td class="left top">Formulas and Recipes</td>
+<td class="right bot"><a href="#Page_Cat29">29</a></td>
+</tr>
+
+<tr>
+<td class="left top">Fuel</td>
+<td class="right bot"><a href="#Page_Cat17">17</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gas Construction</td>
+<td class="right bot"><a href="#Page_Cat18">18</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gas Engines</td>
+<td class="right bot"><a href="#Page_Cat18">18</a>, <a href="#Page_Cat19">19</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gas Tractor</td>
+<td class="right bot"><a href="#Page_Cat33">33</a></td>
+</tr>
+
+<tr>
+<td class="left top">Gearing and Cams</td>
+<td class="right bot"><a href="#Page_Cat19">19</a></td>
+</tr>
+
+<tr>
+<td class="left top">Glossary of Aviation Terms</td>
+<td class="right bot"><a href="#Page_Cat7">7</a>, <a href="#Page_Cat12">12</a></td>
+</tr>
+
+<tr>
+<td class="left top">Heating</td>
+<td class="right bot"><a href="#Page_Cat31">31</a>, <a href="#Page_Cat32">32</a></td>
+</tr>
+
+<tr>
+<td class="left top">Horse-Power Chart</td>
+<td class="right bot"><a href="#Page_Cat9">9</a></td>
+</tr>
+
+<tr>
+<td class="left top">Hot-Water Heating</td>
+<td class="right bot"><a href="#Page_Cat31">31</a>, <a href="#Page_Cat32">32</a></td>
+</tr>
+
+<tr>
+<td class="left top">House Wiring</td>
+<td class="right bot"><a href="#Page_Cat15">15</a>, <a href="#Page_Cat17">17</a></td>
+</tr>
+
+<tr>
+<td class="left top">How to Run an Automobile</td>
+<td class="right bot"><a href="#Page_Cat3">3</a></td>
+</tr>
+
+<tr>
+<td class="left top">Hydraulics</td>
+<td class="right bot"><a href="#Page_Cat5">5</a></td>
+</tr>
+
+<tr>
+<td class="left top">Ice and Refrigeration</td>
+<td class="right bot"><a href="#Page_Cat20">20</a></td>
+</tr>
+
+<tr>
+<td class="left top">Ignition Systems</td>
+<td class="right bot"><a href="#Page_Cat5">5</a></td>
+</tr>
+
+<tr>
+<td class="left top">Ignition-Trouble Chart</td>
+<td class="right bot"><a href="#Page_Cat6">6</a></td>
+</tr>
+
+<tr>
+<td class="left top">India Rubber</td>
+<td class="right bot"><a href="#Page_Cat30">30</a></td>
+</tr>
+
+<tr>
+<td class="left top">Interchangeable Manufacturing</td>
+<td class="right bot"><a href="#Page_Cat24">24</a></td>
+</tr>
+
+<tr>
+<td class="left top">Inventions</td>
+<td class="right bot"><a href="#Page_Cat20">20</a></td>
+</tr>
+
+<tr>
+<td class="left top">Knots</td>
+<td class="right bot"><a href="#Page_Cat20">20</a></td>
+</tr>
+
+<tr>
+<td class="left top">Lathe Work</td>
+<td class="right bot"><a href="#Page_Cat20">20</a></td>
+</tr>
+
+<tr>
+<td class="left top">Link Motions</td>
+<td class="right bot"><a href="#Page_Cat22">22</a></td>
+</tr>
+
+<tr>
+<td class="left top">Liquid Air</td>
+<td class="right bot"><a href="#Page_Cat21">21</a></td>
+</tr>
+
+<tr>
+<td class="left top">Locomotive Boilers</td>
+<td class="right bot"><a href="#Page_Cat22">22</a></td>
+</tr>
+
+<tr>
+<td class="left top">Locomotive Breakdowns</td>
+<td class="right bot"><a href="#Page_Cat22">22</a></td>
+</tr>
+
+<tr>
+<td class="left top">Locomotive Engineering</td>
+<td class="right bot"><a href="#Page_Cat21">21</a>, <a href="#Page_Cat22">22</a>,
+<a href="#Page_Cat23">23</a>, <a href="#Page_Cat24">24</a></td>
+</tr>
+
+<tr>
+<td class="left top">Machinist Book</td>
+<td class="right bot"><a href="#Page_Cat24">24</a>, <a href="#Page_Cat25">25</a>, <a href="#Page_Cat26">26</a></td>
+</tr>
+
+<tr>
+<td class="left top">Magazine, Mechanical</td>
+<td class="right bot"><a href="#Page_Cat34">34</a></td>
+</tr>
+
+<tr>
+<td class="left top">Manual Training</td>
+<td class="right bot"><a href="#Page_Cat26">26</a></td>
+</tr>
+
+<tr>
+<td class="left top">Marine Engineering</td>
+<td class="right bot"><a href="#Page_Cat26">26</a></td>
+</tr>
+
+<tr>
+<td class="left top">Marine Gasoline Engines</td>
+<td class="right bot"><a href="#Page_Cat19">19</a></td>
+</tr>
+
+<tr>
+<td class="left top">Mechanical Drawing</td>
+<td class="right bot"><a href="#Page_Cat13">13</a>, <a href="#Page_Cat14">14</a></td>
+</tr>
+
+<tr>
+<td class="left top">Mechanical Magazine</td>
+<td class="right bot"><a href="#Page_Cat34">34</a></td>
+</tr>
+
+<tr>
+<td class="left top">Mechanical Movements</td>
+<td class="right bot"><a href="#Page_Cat25">25</a></td>
+</tr>
+
+<tr>
+<td class="left top">Metal Work</td>
+<td class="right bot"><a href="#Page_Cat12">12</a>, <a href="#Page_Cat13">13</a></td>
+</tr>
+
+<tr>
+<td class="left top">Motorcycles</td>
+<td class="right bot"><a href="#Page_Cat5">5</a>, <a href="#Page_Cat6">6</a></td>
+</tr>
+
+<tr>
+<td class="left top">Patents</td>
+<td class="right bot"><a href="#Page_Cat20">20</a></td>
+</tr>
+
+<tr>
+<td class="left top">Pattern Making</td>
+<td class="right bot"><a href="#Page_Cat27">27</a></td>
+</tr>
+
+<tr>
+<td class="left top">Perfumery</td>
+<td class="right bot"><a href="#Page_Cat27">27</a></td>
+</tr>
+
+<tr>
+<td class="left top">Perspective</td>
+<td class="right bot"><a href="#Page_Cat13">13</a></td>
+</tr>
+
+<tr>
+<td class="left top">Plumbing</td>
+<td class="right bot"><a href="#Page_Cat28">28</a>, <a href="#Page_Cat29">29</a></td>
+</tr>
+
+<tr>
+<td class="left top">Producer Gas</td>
+<td class="right bot"><a href="#Page_Cat19">19</a></td>
+</tr>
+
+<tr>
+<td class="left top">Punches</td>
+<td class="right bot"><a href="#Page_Cat13">13</a></td>
+</tr>
+
+<tr>
+<td class="left top">Questions and Answers on Automobile</td>
+<td class="right bot"><a href="#Page_Cat4">4</a></td>
+</tr>
+
+<tr>
+<td class="left top">Questions on Heating</td>
+<td class="right bot"><a href="#Page_Cat32">32</a></td>
+</tr>
+
+<tr>
+<td class="left top">Railroad Accidents</td>
+<td class="right bot"><a href="#Page_Cat23">23</a></td>
+</tr>
+
+<tr>
+<td class="left top">Railroad Charts</td>
+<td class="right bot"><a href="#Page_Cat9">9</a></td>
+</tr>
+
+<tr>
+<td class="left top">Recipe Book</td>
+<td class="right bot"><a href="#Page_Cat29">29</a></td>
+</tr>
+
+<tr>
+<td class="left top">Refrigeration</td>
+<td class="right bot"><a href="#Page_Cat20">20</a></td>
+</tr>
+
+<tr>
+<td class="left top">Repairing Automobiles</td>
+<td class="right bot"><a href="#Page_Cat4">4</a></td>
+</tr>
+
+<tr>
+<td class="left top">Rope Work</td>
+<td class="right bot"><a href="#Page_Cat20">20</a></td>
+</tr>
+
+<tr>
+<td class="left top">Rubber</td>
+<td class="right bot"><a href="#Page_Cat30">30</a></td>
+</tr>
+
+<tr>
+<td class="left top">Rubber Stamps</td>
+<td class="right bot"><a href="#Page_Cat30">30</a></td>
+</tr>
+
+<tr>
+<td class="left top">Saw Filing</td>
+<td class="right bot"><a href="#Page_Cat30">30</a></td>
+</tr>
+
+<tr>
+<td class="left top">Saws, Management of</td>
+<td class="right bot"><a href="#Page_Cat30">30</a></td>
+</tr>
+
+<tr>
+<td class="left top">Sheet-Metal Works</td>
+<td class="right bot"><a href="#Page_Cat12">12</a>, <a href="#Page_Cat13">13</a></td>
+</tr>
+
+<tr>
+<td class="left top">Shop Construction</td>
+<td class="right bot"><a href="#Page_Cat25">25</a></td>
+</tr>
+
+<tr>
+<td class="left top">Shop Management</td>
+<td class="right bot"><a href="#Page_Cat25">25</a></td>
+</tr>
+
+<tr>
+<td class="left top">Shop Practice</td>
+<td class="right bot"><a href="#Page_Cat25">25</a></td>
+</tr>
+
+<tr>
+<td class="left top">Shop Tools</td>
+<td class="right bot"><a href="#Page_Cat25">25</a></td>
+</tr>
+
+<tr>
+<td class="left top">Sketching Paper</td>
+<td class="right bot"><a href="#Page_Cat14">14</a></td>
+</tr>
+
+<tr>
+<td class="left top">Soldering</td>
+<td class="right bot"><a href="#Page_Cat7">7</a></td>
+</tr>
+
+<tr>
+<td class="left top">Splices and Rope Work</td>
+<td class="right bot"><a href="#Page_Cat20">20</a></td>
+</tr>
+
+<tr>
+<td class="left top">Steam Engineering</td>
+<td class="right bot"><a href="#Page_Cat30">30</a>, <a href="#Page_Cat31">31</a></td>
+</tr>
+
+<tr>
+<td class="left top">Steam Heating</td>
+<td class="right bot"><a href="#Page_Cat31">31</a>, <a href="#Page_Cat32">32</a></td>
+</tr>
+
+<tr>
+<td class="left top">Steel</td>
+<td class="right bot"><a href="#Page_Cat32">32</a></td>
+</tr>
+
+<tr>
+<td class="left top">Storage Batteries</td>
+<td class="right bot"><a href="#Page_Cat5">5</a></td>
+</tr>
+
+<tr>
+<td class="left top">Submarine Chart</td>
+<td class="right bot"><a href="#Page_Cat9">9</a></td>
+</tr>
+
+<tr>
+<td class="left top">Switchboards</td>
+<td class="right bot"><a href="#Page_Cat14">14</a>, <a href="#Page_Cat16">16</a></td>
+</tr>
+
+<tr>
+<td class="left top">Tapers</td>
+<td class="right bot"><a href="#Page_Cat21">21</a></td>
+</tr>
+
+<tr>
+<td class="left top">Telegraphy, Wireless</td>
+<td class="right bot"><a href="#Page_Cat17">17</a></td>
+</tr>
+
+<tr>
+<td class="left top">Telephone</td>
+<td class="right bot"><a href="#Page_Cat16">16</a></td>
+</tr>
+
+<tr>
+<td class="left top">Thread Cutting</td>
+<td class="right bot"><a href="#Page_Cat26">26</a></td>
+</tr>
+
+<tr>
+<td class="left top">Tool Making</td>
+<td class="right bot"><a href="#Page_Cat24">24</a></td>
+</tr>
+
+<tr>
+<td class="left top">Toy Making</td>
+<td class="right bot"><a href="#Page_Cat15">15</a></td>
+</tr>
+
+<tr>
+<td class="left top">Train Rules</td>
+<td class="right bot"><a href="#Page_Cat23">23</a></td>
+</tr>
+
+<tr>
+<td class="left top">Tractive Power Chart</td>
+<td class="right bot"><a href="#Page_Cat9">9</a></td>
+</tr>
+
+<tr>
+<td class="left top">Tractor, Gas</td>
+<td class="right bot"><a href="#Page_Cat33">33</a></td>
+</tr>
+
+<tr>
+<td class="left top">Turbines</td>
+<td class="right bot"><a href="#Page_Cat33">33</a></td>
+</tr>
+
+<tr>
+<td class="left top">Vacuum Heating</td>
+<td class="right bot"><a href="#Page_Cat32">32</a></td>
+</tr>
+
+<tr>
+<td class="left top">Valve Setting</td>
+<td class="right bot"><a href="#Page_Cat22">22</a></td>
+</tr>
+
+<tr>
+<td class="left top">Ventilation</td>
+<td class="right bot"><a href="#Page_Cat31">31</a></td>
+</tr>
+
+<tr>
+<td class="left top">Watch Making</td>
+<td class="right bot"><a href="#Page_Cat33">33</a></td>
+</tr>
+
+<tr>
+<td class="left top">Waterproofing</td>
+<td class="right bot"><a href="#Page_Cat12">12</a></td>
+</tr>
+
+<tr>
+<td class="left top">Welding with Oxy-acetylene Flame</td>
+<td class="right bot"><a href="#Page_Cat5">5</a>, <a href="#Page_Cat33">33</a></td>
+</tr>
+
+<tr>
+<td class="left top">Wireless Telegraphy</td>
+<td class="right bot"><a href="#Page_Cat17">17</a></td>
+</tr>
+
+<tr>
+<td class="left top">Wiring</td>
+<td class="right bot"><a href="#Page_Cat14">14</a>, <a href="#Page_Cat15">15</a></td>
+</tr>
+
+<tr>
+<td class="left top">Wiring Diagrams</td>
+<td class="right bot"><a href="#Page_Cat14">14</a></td>
+</tr>
+
+</table>
+
+<p class="center fsize125"><b>Any of these books promptly sent prepaid to any address in
+the world on receipt of price.</b></p>
+
+<p><span class="fsize125"><b>HOW TO REMIT</b></span>&mdash;By Postal Money Order, Express Money Order,
+Bank Draft or Registered Letter.</p>
+
+<hr class="c25" />
+<p class='pagenum'><a name="Page_Cat3" id="Page_Cat3">[3]</a></p>
+
+<h2>AUTOMOBILES AND MOTORCYCLES</h2>
+
+<p><b>The Modern Gasoline Automobile&mdash;Its Design, Construction, and Operation,
+1918 Edition.</b> By <span class="smcap">Victor W. Pag&eacute;</span>, M.S.A.E.</p>
+
+<div class="blockquot"><p>This is the most complete, practical and up-to-date treatise on gasoline automobiles and their
+component parts ever published. In the new <i>revised</i> and <i>enlarged</i> 1918 <i>edition</i>, all phases of
+automobile construction, operation and maintenance are fully and completely described, and
+in language anyone can understand. Every part of all types of automobiles, from light cycle-cars
+to heavy motor trucks and tractors, are described in a thorough manner, not only
+the automobile, but every item of it; equipment, accessories, tools needed, supplies and spare
+parts necessary for its upkeep, are fully discussed.</p>
+
+<p><i>It is clearly and concisely written by an expert familiar with every branch of the automobile industry
+and the originator of the practical system of self-education on technical subjects. It is a liberal education
+in the automobile art, useful to all who motor for either business or pleasure.</i></p>
+
+<p>Anyone reading the incomparable treatise is in touch with all improvements that have been
+made in motor-car construction. All latest developments, such as high speed aluminum motors
+and multiple valve and sleeve-valve engines, are considered in detail. The latest ignition,
+carburetor and lubrication practice is outlined. New forms of change speed gears, and final
+power transmission systems, and all latest chassis improvements are shown and described.
+This book is used in all leading automobile schools and is conceded to be the <span class="smcap">Standard
+Treatise</span>. The chapter on Starting and Lighting Systems has been greatly enlarged, and
+many automobile engineering features that have long puzzled laymen are explained so clearly
+that the underlying principles can be understood by anyone. This book was first published
+six years ago and so much new matter has been added that it is nearly twice, its original size.
+The only treatise covering various forms of war automobiles and recent developments in motor-truck
+design as well as pleasure cars. <i>This book is not too technical for the layman nor too elementary
+for the more expert. It is an incomparable work of reference, for home or school</i>. 1,000 6x9 pages,
+nearly 1,000 illustrations, 12 folding plates. Cloth bound. Price <span class="price">$3.00</span></p>
+
+<h3>WHAT IS SAID OF THIS BOOK:</h3>
+
+<p>&#8220;It is the best book on the Automobile seen up to date.&#8221;&mdash;J. H. Pile, Associate Editor <i>Automobile
+Trade Journal</i>.</p>
+
+<p>&#8220;Every Automobile Owner has use for a book of this character.&#8221;&mdash;<i>The Tradesman</i>.</p>
+
+<p>&#8220;This book is superior to any treatise heretofore published on the subject.&#8221;&mdash;<i>The Inventive Age</i>.</p>
+
+<p>&#8220;We know of no other volume that is so complete in all its departments, and in which the wide
+field of automobile construction with its mechanical intricacies is so plainly handled, both in
+the text and in the matter of illustrations.&#8221;&mdash;<i>The Motorist</i>.</p>
+
+<p>&#8220;The book is very thorough, a careful examination failing to disclose any point in connection
+with the automobile, its care and repair, to have been overlooked.&#8221;&mdash;<i>Iron Age</i>.</p>
+
+<p>&#8220;Mr. Pag&eacute; has done a great work, and benefit to the Automobile Field.&#8221;&mdash;W. C. Hasford,
+Mgr. Y. M. C. A. Automobile School, Boston, Mass.</p>
+
+<p>&#8220;It is just the kind of a book a motorist needs if he wants to understand his car.&#8221;&mdash;<i>American
+Thresherman</i>.</p></div>
+
+<p><b>The Model T Ford Car, Its Construction, Operation and Repair.</b> By <span class="smcap">Victor
+W. Pag&eacute;</span>, M.S.A.E.</p>
+
+<div class="blockquot"><p>This is a complete instruction book. All parts of the Ford Model T Car are described and
+illustrated; the construction is fully described and operating principles made clear to everyone.
+Every Ford owner needs this practical book. You don&#8217;t have to guess about the construction
+or where the trouble is, as it shows how to take all parts apart and how to locate and fix all
+faults. The writer, Mr. Pag&eacute;, has operated a Ford car for many years and writes from actual
+knowledge. Among the contents are: 1. The Ford Car: Its Parts and Their Functions.
+2. The Engine and Auxiliary Groups. How the Engine Works&mdash;The Fuel Supply System&mdash;The
+Carburetor&mdash;Making the Ignition Spark&mdash;Cooling and Lubrication. 3. Details of Chassis.
+Change Speed Gear&mdash;Power Transmission&mdash;Differential Gear Action&mdash;Steering Gear&mdash;Front
+Axle&mdash;Frame and Springs&mdash;Brakes. 4. How to Drive and Care for the Ford. The Control
+System Explained&mdash;Starting the Motor&mdash;Driving the Car&mdash;Locating Roadside Troubles&mdash;Tire
+Repairs&mdash;Oiling the Chassis&mdash;Winter Care of Car. 5. Systematic Location of Troubles
+and Remedies. Faults in Engine&mdash;Faults in Carburetor&mdash;Ignition Troubles&mdash;Cooling and
+Lubrication System Defects&mdash;Adjustment of Transmission Gear&mdash;General Chassis Repairs.
+95 illustrations, 300 pages, 2 large folding plates. Price <span class="price">$1.00</span></p></div>
+
+<p><b>How to Run an Automobile.</b> By <span class="smcap">Victor W. Pag&eacute;</span>, M.S.A.E.</p>
+
+<div class="blockquot"><p>This treatise gives concise instructions for starting and running all makes of gasoline automobiles,
+how to care for them, and gives distinctive features of control. Describes every
+step for shifting gears, controlling engines, etc. Among the chapters contained are: I.&mdash;Automobile
+Parts and Their Functions. II.&mdash;General Starting and Driving Instructions.
+III.&mdash;Typical 1917 Control Systems. IV.&mdash;Care of Automobiles. 178 pages. 72 specially
+made illustrations. Price <span class="price">$1.00</span></p></div>
+
+<p><span class='pagenum'><a name="Page_Cat4" id="Page_Cat4">[4]</a></span><b>Automobile Repairing Made Easy.</b> By
+<span class="smcap">Victor W. Pag&eacute;</span>, M.S.A.E.</p>
+
+<div class="blockquot"><p>A comprehensive, practical exposition of every phase of modern automobile repairing practice.
+Outlines every process incidental to motor car restoration. Gives plans for workshop
+construction, suggestions for equipment, power needed, machinery and tools necessary to
+carry on business successfully. Tells how to overhaul and repair all parts of all automobiles.
+Everything is explained so simply that motorists and students can acquire a full
+working knowledge of automobile repairing. This work starts with the engine, then considers
+carburetion, ignition, cooling and lubrication systems. The clutch, change speed gearing
+and transmission system are considered in detail. Contains instructions for repairing all
+types of axles, steering gears and other chassis parts. Many tables, short cuts in figuring
+and rules of practice are given for the mechanic. Explains fully valve and magneto timing,
+&#8220;tuning&#8221; engines, systematic location of trouble, repair of ball and roller bearings, shop kinks,
+first aid to injured and a multitude of subjects of interest to all in the garage and repair business.
+<i>This book contains special instructions on electric starting</i>, <i>lighting and ignition systems</i>, tire
+<i>repairing and rebuilding</i>, <i>autogenous welding</i>, <i>brazing and soldering</i>, <i>heat treatment of steel</i>, <i>latest
+timing practice</i>, <i>eight and twelve-cylinder motors</i>, <i>etc.</i>
+5<sup>3</sup>&#8260;<sub>4</sub>x8. Cloth. 1,056 pages, 1,000 illustrations,
+11 folding plates. Price <span class="price">$3.00</span></p>
+
+<h3>WHAT IS SAID OF THIS BOOK:</h3>
+
+<p>&#8220;&#8216;Automobile Repairing Made Easy&#8217; is the best book on the subject I have ever seen and
+the only book I ever saw that is of any value in a garage.&#8221;&mdash;Fred Jeffrey, Martinsburg, Neb.
+&#8220;I wish to thank you for sending me a copy of &#8216;Automobile Repairing Made Easy.&#8217; I do
+not think it could be excelled.&#8221;&mdash;S. W. Gisriel, Director of Instruction, Y. M. C. A., Philadelphia,
+Pa.</p></div>
+
+<p><b>Questions and Answers Relating to Modern Automobile Construction,
+Driving and Repair.</b> By <span class="smcap">Victor W. Pag&eacute;</span>, M.S.A.E.</p>
+
+<div class="blockquot"><p>A practical self-instructor for students, mechanics and motorists, consisting of thirty-seven
+lessons in the form of questions and answers, written with special reference to the requirements
+of the non-technical reader desiring easily understood, explanatory matter relating
+to all branches of automobiling. The subject-matter is absolutely correct and explained in
+simple language. If you can&#8217;t answer all of the following questions, you need this work. The
+answers to these and over 2,000 more are to be found in its pages. Give the name of all important
+parts of an automobile and describe their functions. Describe action of latest types
+of kerosene carburetors. What is the difference between a &#8220;double&#8221; ignition system and a
+&#8220;dual&#8221; ignition system? Name parts of an induction coil. How are valves timed? What
+is an electric motor starter and how does it work? What are advantages of worm drive gearing?
+Name all important types of ball and roller bearings. What is a &#8220;three-quarter&#8221; floating
+axle? What is a two-speed axle? What is the Vulcan electric gear shift? Name the causes
+of lost power in automobiles. Describe all noises due to deranged mechanism and give causes?
+How can you adjust a carburetor by the color of the exhaust gases? What causes &#8220;popping&#8221;
+in the carburetor? What tools and supplies are needed to equip a car? How do you drive
+various makes of cars? What is a differential lock and where is it used? Name different
+systems of wire wheel construction, etc., etc. A popular work at a popular price.
+5<sup>1</sup>&#8260;<sub>4</sub>x7<sup>1</sup>&#8260;<sub>2</sub>.
+Cloth. 650 pages, 350 illustrations, 3 folding plates. Price <span class="price">$1.50</span></p>
+
+<h3>WHAT IS SAID OF THIS BOOK:</h3>
+
+<p>&#8220;If you own a car&mdash;get this book.&#8221;&mdash;<i>The Glassworker</i>.</p>
+
+<p>&#8220;Mr. Page has the faculty of making difficult subjects plain and understandable.&#8221;&mdash;<i>Bristol
+Press</i>.</p>
+
+<p>&#8220;We can name no writer better qualified to prepare a book of instruction on automobiles
+than Mr. Victor W. Pag&eacute;.&#8221;&mdash;<i>Scientific American</i>.</p>
+
+<p>&#8220;The best automobile catechism that has appeared.&#8221;&mdash;<i>Automobile Topics</i>.</p>
+
+<p>&#8220;There are few men, even with long experience, who will not find this book useful. Great
+pains have been taken to make it accurate. Special recommendation must be given to the
+illustrations, which have been made specially for the work. Such excellent books as this
+greatly assist in fully understanding your automobile.&#8221;&mdash;<i>Engineering News</i>.</p></div>
+
+<p><b>The Automobilist&#8217;s Pocket Companion and Expense Record.</b> Arranged by
+<span class="smcap">Victor W. Pag&eacute;</span>, M.S.A.E.</p>
+
+<div class="blockquot"><p>This book is not only valuable as a convenient cost record but contains much information of value
+to motorists. Includes a condensed digest of auto laws of all States, a lubrication schedule,
+hints for care of storage battery and care of tires, location of road troubles, anti-freezing
+solutions, horse-power table, driving hints and many useful tables and recipes of interest to
+all motorists. Not a technical book in any sense of the word, just a collection of practical
+facts in simple language for the everyday motorist. Price <span class="price">$1.00</span></p></div>
+
+<p><span class='pagenum'><a name="Page_Cat5" id="Page_Cat5">[5]</a></span><b>Modern
+Starting, Lighting and Ignition Systems.</b> By <span class="smcap">Victor W. Pag&eacute;</span>, M.E.</p>
+
+<div class="blockquot"><p>This practical volume has been written with special reference to the requirements of the non-technical
+reader desiring easily understood, explanatory matter, relating to all types of automobile
+ignition, starting and lighting systems. It can be understood by anyone, even without
+electrical knowledge, because elementary electrical principles are considered before any attempt
+is made to discuss features of the various systems. These basic principles are clearly
+stated and illustrated with simple diagrams. <i>All the leading systems of starting, lighting and
+ignition have been described and illustrated with the co-operation of the experts employed by the
+manufacturers.</i> Wiring diagrams are shown in both technical and non-technical forms. All
+symbols are fully explained. It is a comprehensive review of modern starting and ignition
+system practice, and includes a complete exposition of storage battery construction, care and
+repair. All types of starting motors, generators, magnetos, and all ignition or lighting system-units
+are fully explained. <i>Every person in the automobile business needs this volume.</i> Among
+some of the subjects treated are: I.&mdash;Elementary Electricity; Current Production; Flow;
+Circuits; Measurements; Definitions; Magnetism; Battery Action; Generator Action. II.&mdash;Battery
+Ignition Systems. III.&mdash;Magneto Ignition Systems. IV.&mdash;Elementary Exposition of Starting
+System Principles. V.&mdash;Typical Starting and Lighting Systems; Practical Application; Wiring
+Diagrams; Auto-lite, Bijur, Delco, Dyneto-Entz, Gray and Davis, Remy, U. S. L., Westinghouse,
+Bosch-Rushmore, Genemotor, North-East, etc. VI.&mdash;Locating and Repairing Troubles in Starting
+and Lighting Systems. VII.&mdash;Auxiliary. Electric Systems; Gear-shifting by Electricity;
+Warning Signals; Electric Brake; Entz-Transmission, Wagner-Saxon Circuits, Wagner-Studebaker
+Circuits. 5<sup>1</sup>&#8260;<sub>4</sub>x7<sup>1</sup>&#8260;<sub>2</sub>. Cloth. 530 pages, 297 illustrations, 3 folding plates.
+Price <span class="price">$1.50</span></p></div>
+
+<p><b>Automobile Welding With the Oxy-Acetylene Flame.</b> By <span class="smcap">M. Keith Dunham</span>.</p>
+
+<div class="blockquot"><p>This is the only complete book on the &#8220;why&#8221; and &#8220;how&#8221; of Welding with the Oxy-Acetylene
+Flame, and from its pages one can gain information so that he can weld anything that comes
+along.</p>
+
+<p>No one can afford to be without this concise book, as it first explains the apparatus to be
+used, and then covers in detail the actual welding of all automobile parts. The welding of
+aluminum, cast iron, steel, copper, brass and malleable iron is clearly explained, as well
+as the proper way to burn the carbon out of the combustion head of the motor. Among the
+contents are: Chapter I.&mdash;Apparatus Knowledge. Chapter II.&mdash;Shop Equipment and
+Initial Procedure. Chapter III.&mdash;Cast Iron. Chapter IV.&mdash;Aluminum. Chapter V.&mdash;Steel.
+Chapter VI.&mdash;Malleable Iron, Copper, Brass, Bronze. Chapter VII.&mdash;Carbon Burning
+and other Uses of Oxygen and Acetylene. Chapter VIII.&mdash;How to Figure Cost of Welding.
+167 pages, fully illustrated. Price <span class="price">$1.00</span></p></div>
+
+<p><b>Storage Batteries Simplified.</b> By <span class="smcap">Victor W. Pag&eacute;</span>, M.S.A.E.</p>
+
+<div class="blockquot"><p>A comprehensive treatise devoted entirely to secondary batteries and their maintenance,
+repair and use.</p>
+
+<p>This is the most up-to-date book on this subject. Describes fully the Exide, Edison, Gould,
+Willard, U. S. L. and other storage battery forms in the types best suited for automobile,
+stationary and marine work. Nothing of importance has been omitted that the reader should
+know about the practical operation and care of storage batteries. No details have been
+slighted. The instructions for charging and care have been made as simple as possible. Brief
+Synopsis of Chapters: Chapter I.&mdash;Storage Battery Development; Types of Storage Batteries;
+Lead Plate Types; The Edison Cell. Chapter II.&mdash;Storage Battery Construction;
+Plates and Girds; Plant&eacute; Plates; Faur&eacute; Plates; Non-Lead Plates; Commercial Battery
+Designs. Chapter III.&mdash;Charging Methods; Rectifiers; Converters; Rheostats; Rules
+for Charging. Chapter IV.&mdash;Battery Repairs and Maintenance. Chapter V.&mdash;Industrial
+Application of Storage Batteries; Glossary of Storage Battery Terms. 208 Pages. Very
+Fully Illustrated. Price <span class="price">$1.50 net.</span></p></div>
+
+<p><b>Motorcycles, Side Cars and Cyclecars; their Construction, Management
+and Repair.</b> By <span class="smcap">Victor W. Pag&eacute;</span>, M.S.A.E.</p>
+
+<div class="blockquot"><p>The only complete work published for the motorcyclist and cyclecarist. Describes fully all
+leading types of machines, their design, construction, maintenance, operation and repair.
+This treatise outlines fully the operation of two- and four-cycle power plants and all ignition,
+carburetion and lubrication systems in detail. Describes all representative types of free
+engine clutches, variable speed gears and power transmission systems. Gives complete instructions
+for operating and repairing all types. Considers fully electric self-starting and
+lighting systems, all types of spring frames and spring forks and shows leading control methods.
+For those desiring technical information a complete series of tables and many formul&aelig; to
+assist in designing are included. The work tells how to figure power needed to climb grades,
+overcome air resistance and attain high speeds. It shows how to select gear ratios for various
+weights and powers, how to figure braking efficiency required, gives sizes of belts and chains
+to transmit power safely, and shows how to design sprockets, belt pulleys, etc. This work
+also includes complete formul&aelig; for figuring horse-power, shows how dynamometer tests
+are<span class='pagenum'><a name="Page_Cat6" id="Page_Cat6">[6]</a></span>
+made, defines relative efficiency of air and water-cooled engines, plain and anti-friction bearings
+and many other data of a practical, helpful, engineering nature. Remember that you
+get this information in addition to the practical description and instructions which alone are
+worth several times the price of the book. 550 pages. 350 specially made illustrations, 5
+folding plates. Cloth. Price <span class="price">$1.50</span></p>
+
+<h3>WHAT IS SAID OF THIS BOOK:</h3>
+
+<p>&#8220;Here is a book that should be in the cycle repairer&#8217;s kit.&#8221;&mdash;<i>American Blacksmith.</i></p>
+
+<p>&#8220;The best way for any rider to thoroughly understand his machine, is to get a copy of this
+book; it is worth many times its price.&#8221;&mdash;<i>Pacific Motorcyclist.</i></p></div>
+
+<h2>AUTOMOBILE AND MOTORCYCLE CHARTS</h2>
+
+<p><b>Chart. Location of Gasoline Engine Troubles Made Easy&mdash;A Chart Showing
+Sectional View of Gasoline Engine.</b> Compiled by <span class="smcap">Victor W. Pag&eacute;</span>,
+M.S.A.E.</p>
+
+<div class="blockquot"><p>It shows clearly all parts of a typical four-cylinder gasoline engine of the four-cycle type.</p>
+
+<p>It outlines distinctly all parts liable to give trouble and also details the derangements apt
+to interfere with smooth engine operation.</p>
+
+<p>Valuable to students, motorists, mechanics, repairmen, garagemen, automobile salesmen,
+chauffeurs, motorboat owners, motor-truck and tractor drivers, aviators, motor-cyclists,
+and all others who have to do with gasoline power plants.</p>
+
+<p>It simplifies location of all engine troubles, and while it will prove invaluable to the novice,
+it can be used to advantage by the more expert. It should be on the walls of every public
+and private garage, automobile repair shop, club house or school. It can be carried in the
+automobile or pocket with ease, and will insure against loss of time when engine trouble
+manifests itself.</p>
+
+<p>This sectional view of engine is a complete review of all motor troubles. It is prepared by a
+practical motorist for all who motor. More information for the money than ever before
+offered. No details omitted. Size 25x38 inches. Securely mailed on receipt of <span class="price">25 Cents</span></p></div>
+
+<p><b>Chart. Location of Ford Engine Troubles Made Easy.</b> Compiled by <span class="smcap">Victor
+W. Pag&eacute;</span>, M.S.A.E.</p>
+
+<div class="blockquot"><p>This shows clear sectional views depicting all portions of the Ford power plant and auxiliary
+groups. It outlines clearly all parts of the engine, fuel supply system, ignition group and
+cooling system, that are apt to give trouble, detailing all derangements that are liable to
+make an engine lose power, start hard or work irregularly. This chart is valuable to students,
+owners, and drivers, as it simplifies location of all engine faults. Of great advantage as an
+instructor for the novice, it can be used equally well by the more expert as a work of reference
+and review. It can be carried in the tool-box or pocket with ease and will save its cost in
+labor eliminated the first time engine trouble manifests itself. Prepared with special reference
+to the average man&#8217;s needs and is a practical review of all motor troubles because it is based
+on the actual experience of an automobile engineer-mechanic with the mechanism the chart
+describes. It enables the non-technical owner or operator of a Ford car to locate engine
+derangements by systematic search, guided by easily recognized symptoms instead of by
+guesswork. It makes the average owner independent of the roadside repair shop when touring.
+Must be seen to be appreciated. Size 25x38 inches. Printed on heavy bond paper.
+Price <span class="price">25 cents</span></p></div>
+
+<p><b>Chart. Lubrication of the Motor Car Chassis.</b> Compiled by <span class="smcap">Victor W.
+Pag&eacute;</span>, M.S.A.E.</p>
+
+<div class="blockquot"><p>This chart presents the plan view of a typical six-cylinder chassis of standard design and all
+parts are clearly indicated that demand oil, also the frequency with which they must be
+lubricated and the kind of oil to use. A practical chart for all interested in motor-car maintenance.
+Size 24x38 inches. Price <span class="price">25 cents</span></p></div>
+
+<p><b>Chart. Location of Carburetion Troubles Made Easy.</b> Compiled by <span class="smcap">Victor
+W. Pag&eacute;</span>, M.S.A.E.</p>
+
+<div class="blockquot"><p>This chart shows all parts of a typical pressure feed fuel supply system and gives causes of
+trouble, how to locate defects and means of remedying them. Size 24x38 inches.
+Price <span class="price">25 cents</span></p></div>
+
+<p><b>Chart. Location of Ignition System Troubles Made Easy.</b> Compiled by
+<span class="smcap">Victor W. Pag&eacute;</span>, M.S.A.E.</p>
+
+<div class="blockquot"><p>In this diagram all parts of a typical double ignition system using battery and magneto current
+are shown, and suggestions are given for readily finding ignition troubles and eliminating
+them when found. Size 24x38 inches. Price <span class="price">25 cents</span></p></div>
+
+<p><span class='pagenum'><a name="Page_Cat7" id="Page_Cat7">[7]</a></span><b>Chart.
+Location of Cooling and Lubrication System Faults.</b> Compiled by
+<span class="smcap">Victor W. Pag&eacute;</span>, M.S.A.E.</p>
+
+<div class="blockquot"><p>This composite diagram shows a typical automobile power plant using pump circulated
+water-cooling system and the most popular lubrication method. Gives suggestions for curing
+all overheating and loss of power faults due to faulty action of the oiling or cooling group.
+Size 24x38 inches. Price <span class="price">25 cents</span></p></div>
+
+<p><b>Chart. Motorcycle Troubles Made Easy.</b> Compiled by <span class="smcap">Victor W Pag&eacute;</span>,
+M.S.A.E.</p>
+
+<div class="blockquot"><p>A chart showing sectional view of a single-cylinder gasoline engine. This chart simplifies
+location of all power-plant troubles. A single-cylinder motor is shown for simplicity. It
+outlines distinctly all parts liable to give trouble and also details the derangements apt to
+interfere with smooth engine operation. This chart will prove of value to all who have to do
+with the operation, repair or sale of motorcycles. No details omitted. Size 30x20 inches
+Price <span class="price">25 cents</span></p></div>
+
+<h2>AVIATION</h2>
+
+<p><b>Aviation Engines, their Design, Construction, Operation and Repair.</b> By
+Lieut. <span class="smcap">Victor W. Pag&eacute;</span>, Aviation Section, S.C.U.S.R.</p>
+
+<div class="blockquot"><p>A practical work containing valuable instructions for aviation students, mechanicians,
+squadron engineering officers and all interested in the construction and upkeep of airplane
+power plants.</p>
+
+<p>The rapidly increasing interest in the study of aviation, and especially of the highly developed
+internal combustion engines that make mechanical flight possible, has created a demand for a
+text-book suitable for schools and home study that will clearly and concisely explain the
+workings of the various aircraft engines of foreign and domestic manufacture.</p>
+
+<p>This treatise, written by a recognized authority on all of the practical aspects of internal
+combustion engine construction, maintenance and repair fills the need as no other book does.</p>
+
+<p>The matter is logically arranged; all descriptive matter is simply expressed and copiously
+illustrated so that anyone can understand airplane engine operation and repair even if without
+previous mechanical training. This work is invaluable for anyone desiring to become an
+aviator or aviation mechanician.</p>
+
+<p>The latest rotary types, such as the Gnome, Monosoupape, and Le Rhone, are fully explained,
+as well as the recently developed Vee and radial types. The subjects of carburetion, ignition,
+cooling and lubrication also are covered in a thorough manner. The chapters on repair and
+maintenance are distinctive and found in no other book on this subject.</p>
+
+<p>Invaluable to the student, mechanic and soldier wishing to enter the aviation service.</p>
+
+<p>Not a technical book, but a practical, easily understood work of reference for all interested
+in aeronautical science. 576 octavo pages. 253 specially made engravings. Price <span class="price">$3.00 net</span></p></div>
+
+<h2>GLOSSARY OF AVIATION TERMS</h2>
+
+<p><b>Termes D&#8217;Aviation, English-French, French-English.</b> Compiled by Lieuts.
+<span class="smcap">Victor W. Pag&eacute;</span>, A.S., S.C.U.S.R., and <span class="smcap">Paul Montariol</span> of the French
+Flying Corps, on duty on Signal Corps Aviation School, Mineola, L. I.</p>
+
+<div class="blockquot"><p>A complete, well illustrated volume intended to facilitate conversation between English-speaking
+and French aviators. A very valuable book for all who are about to leave for duty
+overseas.</p>
+
+<p>Approved for publication by Major W. G. Kilner, S.C., U.S.C.O. Signal Corps Aviation
+School. Hazelhurst Field, Mineola, L. I.</p>
+
+<p>This book should be in every Aviator&#8217;s and Mechanic&#8217;s Kit for ready reference. 128 pages.
+Fully illustrated with detailed engravings. Price <span class="price">$1.00</span></p></div>
+
+<p><b>Aviation Chart. Location of Airplane Power Plant Troubles Made Easy.</b>
+By Lieut. <span class="smcap">Victor W. Pag&eacute;</span>, A.S., S.C.U.S.R.</p>
+
+<div class="blockquot"><p>A large chart outlining all parts of a typical airplane power plant, showing the points where
+trouble is apt to occur and suggesting remedies for the common defects. Intended especially
+for Aviators and Aviation Mechanics on School and Field Duty. Price <span class="price">50 cents</span></p></div>
+
+<h3>BRAZING AND SOLDERING</h3>
+
+<p><b>Brazing and Soldering.</b> By <span class="smcap">James F. Hobart.</span></p>
+
+<div class="blockquot"><p>The only book that shows you just how to handle any job of brazing or soldering that comes
+along; it tells you what mixture to use, how to make a furnace if you need one. Full of valuable
+kinks. The fifth edition of this book has just been published, and to it much new matter
+and a large number of tested formul&aelig; for all kinds of solders and fluxes have been added.
+Illustrated. Price <span class="price">25 cents</span></p></div>
+
+<p class='pagenum'><a name="Page_Cat8" id="Page_Cat8">[8]</a></p>
+
+<h3>CHARTS</h3>
+
+<p><b>Aviation Chart. Location of Airplane Power Plant Troubles Made Easy.</b>
+By Lieut. <span class="smcap">Victor W. Pag&eacute;</span>, A.S., S.C.U.S.R.</p>
+
+<div class="blockquot"><p>A large chart outlining all parts of a typical airplane power plant, showing the points where
+trouble is apt to occur and suggesting remedies for the common defects. Intended especially
+for Aviators and Aviation Mechanics on School and Field Duty. Price <span class="price">50 cents</span></p></div>
+
+<p><b>Gasoline Engine Troubles Made Easy&mdash;A Chart Showing Sectional View of
+Gasoline Engine.</b> Compiled by Lieut. <span class="smcap">Victor W. Pag&eacute;</span>, A.S., S.C.U.S.R.</p>
+
+<div class="blockquot"><p>It shows clearly all parts of a typical four-cylinder gasoline engine of the four-cycle type.
+It outlines distinctly all parts liable to give trouble and also details the derangements apt
+to interfere with smooth engine operation.</p>
+
+<p>Valuable to students, motorists, mechanics, repairmen, garagemen, automobile salesmen,
+chauffeurs, motor-boat owners, motor-truck and tractor drivers, aviators, motor-cyclists,
+and all others who have to do with gasoline power plants.</p>
+
+<p>It simplifies location of all engine troubles, and while it will prove invaluable to the novice,
+it can be used to advantage by the more expert. It should be on the walls of every public
+and private garage, automobile repair shop, club house or school. It can be carried in the
+automobile or pocket with ease and will insure against loss of time when engine trouble manifests
+itself.</p>
+
+<p>This sectional view of engine is a complete review of all motor troubles. It is prepared by a
+practical motorist for all who motor. No details omitted. Size 25x38 inches. Price <span class="price">25 cents</span></p></div>
+
+<p><b>Lubrication of the Motor Car Chassis.</b></p>
+
+<div class="blockquot"><p>This chart presents the plan view of a typical six-cylinder chassis of standard design and
+all parts are clearly indicated that demand oil, also the frequency with which they must be
+lubricated and the kind of oil to use. A practical chart for all interested in motor-car maintenance.
+Size 24x38 inches. Price <span class="price">25 cents</span></p></div>
+
+<p><b>Location of Carburetion Troubles Made Easy.</b></p>
+
+<div class="blockquot"><p>This chart shows all parts of a typical pressure feed fuel supply system and gives causes of
+trouble, how to locate defects and means of remedying them. Size 24x38 inches.
+Price <span class="price">25 cents</span></p></div>
+
+<p><b>Location of Ignition System Troubles Made Easy.</b></p>
+
+<div class="blockquot"><p>In this chart all parts of a typical double ignition system using battery and magneto current
+are shown and suggestions are given for readily finding ignition troubles and eliminating
+them when found. Size 24x38 inches. Price <span class="price">25 cents</span></p></div>
+
+<p><b>Location of Cooling and Lubrication System Faults.</b></p>
+
+<div class="blockquot"><p>This composite chart shows a typical automobile power plant using pump circulated water-cooling
+system and the most popular lubrication method. Gives suggestions for curing all
+overheating and loss of power faults due to faulty action of the oiling or cooling group. Size
+24x38 inches. Price <span class="price">25 Cents</span></p></div>
+
+<p><b>Motorcycle Troubles Made Easy&mdash;A Chart Showing Sectional View of Single-Cylinder
+Gasoline Engine.</b> Compiled by <span class="smcap">Victor W. Pag&eacute;</span>, M.S.A.E.</p>
+
+<div class="blockquot"><p>This chart simplifies location of all power-plant troubles, and will prove invaluable to all
+who have to do with the operation, repair or sale of motorcycles. No details omitted. Size
+25x38 inches. Price <span class="price">25 cents</span></p></div>
+
+<p><b>Location of Ford Engine Troubles Made Easy.</b> Compiled by <span class="smcap">Victor W.
+Pag&eacute;</span>, M.S.A.E.</p>
+
+<div class="blockquot"><p>This shows clear sectional views depicting all portions of the Ford power plant and auxiliary
+groups. It outlines clearly all parts of the engine, fuel supply system, ignition group and
+cooling system, that are apt to give trouble, detailing all derangements that are liable to
+make an engine lose power, start hard or work irregularly. This chart is valuable to students,
+owners, and drivers, as it simplifies location of all engine faults. Of great advantage as an
+instructor for the novice, it can be used equally well by the more expert as a work of reference
+and review. It can be carried in the toolbox or pocket with ease and will save its cost in
+labor eliminated the first time engine trouble manifests itself. Prepared with special reference
+to the average man&#8217;s needs and is a practical review of all motor troubles because it is
+based on the actual experience of an automobile engineer-mechanic with the mechanism the
+chart describes. It enables the non-technical owner or operator of a Ford car to locate engine
+derangements by systematic search, guided by easily recognized symptoms instead of
+by guesswork. It makes the average owner independent of the roadside repair shop when
+touring. Must be seen to be appreciated. Size 25x38 inches. Printed on heavy bond paper.
+Price <span class="price">25 cents</span></p></div>
+
+<p><span class='pagenum'><a name="Page_Cat9" id="Page_Cat9">[9]</a></span><b>Modern
+Submarine Chart&mdash;with Two Hundred Parts Numbered and Named.</b></p>
+
+<div class="blockquot"><p>A cross-section view, showing clearly and distinctly all the interior of a Submarine of the
+latest type. You get more information from this chart, about the construction and operation
+of a Submarine, than in any other way. No details omitted&mdash;everything is accurate
+and to scale. It is absolutely correct in every detail, having been approved by Naval Engineers.
+All the machinery and devices fitted in a modern Submarine Boat are shown, and
+to make the engraving more readily understood all the features are shown in operative form,
+with Officers and Men in the act of performing the duties assigned to them in service conditions.
+This CHART IS REALLY AN ENCYCLOPEDIA OF A SUBMARINE. It
+is educational and worth many times its cost. Mailed in a Tube for <span class="price">25 Cents</span></p></div>
+
+<p><b>Box Car Chart.</b></p>
+
+<div class="blockquot"><p>A chart showing the anatomy of a box car, having every part of the car numbered and its
+proper name given in a reference list. Price <span class="price">25 Cents</span></p></div>
+
+<p><b>Gondola Car Chart.</b></p>
+
+<div class="blockquot"><p>A chart showing the anatomy of a gondola car, having every part of the car numbered and
+its proper reference name given in a reference list. Price <span class="price">25 Cents</span></p></div>
+
+<p><b>Passenger-Car Chart.</b></p>
+
+<div class="blockquot"><p>A chart showing the anatomy of a passenger-car, having every part of the car numbered
+and its proper name given in a reference list <span class="price">25 Cents</span></p></div>
+
+<p><b>Steel Hopper Bottom Coal Car.</b></p>
+
+<div class="blockquot"><p>A chart showing the anatomy of a steel Hopper Bottom Coal Car, having every part of the
+car numbered and its proper name given in a reference list. Price <span class="price">25 Cents</span></p></div>
+
+<p><b>Tractive Power Chart.</b></p>
+
+<div class="blockquot"><p>A chart whereby you can find the tractive power or drawbar pull of any locomotive without
+making a figure. Shows what cylinders are equal, how driving wheels and steam pressure
+affect the power. What sized engine you need to exert a given drawbar pull or anything you
+desire in this line. Price <span class="price">50 Cents</span></p></div>
+
+<p><b>Horse-Power Chart.</b></p>
+
+<div class="blockquot"><p>Shows the horse-power of any stationary engine without calculation. No matter what the
+cylinder diameter of stroke, the steam pressure of cut-off, the revolutions, or whether condensing
+or non-condensing, it&#8217;s all there. Easy to use, accurate, and saves time and calculations.
+Especially useful to engineers and designers. Price <span class="price">50 Cents</span></p></div>
+
+<p><b>Boiler Room Chart.</b> By <span class="smcap">Geo. L. Fowler.</span></p>
+
+<div class="blockquot"><p>A chart&mdash;size 14x28 inches&mdash;showing in isometric perspective the mechanisms belonging in
+a modern boiler room. The various parts are shown broken or removed, so that the internal
+construction is fully illustrated. Each part is given a reference number, and these, with the
+corresponding name, are given in a glossary printed at the sides. This chart is really a dictionary
+of the boiler room&mdash;the names of more than 200 parts being given. Price <span class="price">25 Cents</span></p></div>
+
+<h2>COKE</h2>
+
+<p><b>Modern Coking Practice, Including Analysis of Materials and Products.</b></p>
+
+<p>By <span class="smcap">J. E. Christopher</span> and <span class="smcap">T. H. Byrom</span>.</p>
+
+<div class="blockquot"><p>This, the standard work on the subject, has just been revised. It is a practical work for those
+engaged in Coke manufacture and the recovery of By-products. Fully illustrated with folding
+plates. It has been the aim of the authors, in preparing this book, to produce one which
+shall be of use and benefit to those who are associated with, or interested in, the modern
+developments of the industry. Among the Chapters contained in Volume I are: Introduction;
+Classification of Fuels; Impurities of Coals; Coal Washing; Sampling and Valuation
+of Coals, etc.; Power of Fuels; History of Coke Manufacture; Developments in the Coke
+Oven Design; Recent Types of Coke Ovens; Mechanical Appliances at Coke Ovens; Chemical
+and Physical Examination of Coke. Volume II covers fully the subject of By-Products.
+Price, per volume <span class="price">$3.00 net</span></p></div>
+
+<p class='pagenum'><a name="Page_Cat10" id="Page_Cat10">[10]</a></p>
+
+<h2>COMPRESSED AIR</h2>
+
+<p><b>Compressed Air in All Its Applications.</b> By <span class="smcap">Gardner D. Hiscox</span>.</p>
+
+<div class="blockquot"><p>This is the most complete book on the subject of Air that has ever been issued, and its thirty-five
+chapters include about every phase of the subject one can think of. It may be called
+an encyclopedia of compressed air. It is written by an expert, who, in its 665 pages, has
+dealt with the subject in a comprehensive manner, no phase of it being omitted. Includes
+the physical properties of air from a vacuum to its highest pressure, its thermodynamics,
+compression, transmission and uses as a motive power, in the Operation of Stationary and
+Portable Machinery, in Mining, Air Tools, Air Lifts, Pumping of Water, Acids, and Oils;
+the Air Blast for Cleaning and Painting the Sand Blast and its Work, and the Numerous
+Appliances in which Compressed Air is a Most Convenient and Economical Transmitter of
+Power for Mechanical Work, Railway Propulsion, Refrigeration, and the Various Uses to which
+Compressed Air has been applied. Includes forty-four tables of the physical properties of
+air, its compression, expansion, and volumes required for various kinds of work, and a list
+of patents on compressed air from 1875 to date. Over 500 illustrations, 5th Edition, revised
+and enlarged.</p>
+
+<p>Cloth bound. Price <span class="price">$5.00</span></p>
+
+<p>Half Morocco. Price <span class="price">$6.50</span></p></div>
+
+<h2>CONCRETE</h2>
+
+<p><b>Concrete Workers&#8217; Reference Books. A Series of Popular Handbooks for
+Concrete Users.</b> Prepared by <span class="smcap">A. A. Houghton</span> <span class="price">50 cents</span></p>
+
+<p><i>The author, in preparing this Series, has not only treated on the usual types of construction, but
+explains and illustrates molds and systems that are not patented, but which are equal in value
+and often superior to those restricted by patents. These molds are very easily and cheaply constructed
+and embody simplicity, rapidity of operation, and the most successful results in the molded
+concrete. Each of these books is fully illustrated, and the subjects are exhaustively treated in plain
+English.</i></p>
+
+<p><b>Concrete Wall Forms.</b> By <span class="smcap">A. A. Houghton</span>.</p>
+
+<div class="blockquot"><p>A new automatic wall clamp is illustrated with working drawings. Other types of wall forms,
+clamps, separators, etc., are also illustrated and explained. (No. 1 of Series) Price <span class="price">50 cents</span></p></div>
+
+<p><b>Concrete Floors and Sidewalks.</b> By <span class="smcap">A. A. Houghton</span>.</p>
+
+<div class="blockquot"><p>The molds for molding squares, hexagonal and many other styles of mosaic floor and sidewalk
+blocks are fully illustrated and explained. (No. 2 of Series) Price <span class="price">50 cents</span></p></div>
+
+<p><b>Practical Concrete Silo Construction.</b> By <span class="smcap">A. A. Houghton</span>.</p>
+
+<div class="blockquot"><p>Complete working drawings and specifications are given for several styles of concrete silos,
+with illustrations of molds for monolithic and block silos. The tables, data, and information
+presented in this book are of the utmost value in planning and constructing all forms of concrete
+silos. (No. 3 of Series) Price <span class="price">50 cents</span></p></div>
+
+<p><b>Molding Concrete Chimneys, Slate and Hoof Tiles.</b> By <span class="smcap">A. A. Houghton</span>.</p>
+
+<div class="blockquot"><p>The manufacture of all types of concrete slate and roof tile is fully treated. Valuable data
+on all forms of reinforced concrete roofs are contained within its pages. The construction
+of concrete chimneys by block and monolithic systems is fully illustrated and described. A
+number of ornamental designs of chimney construction with molds are shown in this valuable
+treatise. (No. 4 of Series.) Price <span class="price">50 cents</span></p></div>
+
+<p><b>Molding and Curing Ornamental Concrete.</b> By <span class="smcap">A. A. Houghton</span>.</p>
+
+<div class="blockquot"><p>The proper proportions of cement and aggregates for various finishes, also the method of
+thoroughly mixing and placing in the molds, are fully treated. An exhaustive treatise on
+this subject that every concrete worker will find of daily use and value. (No. 5 of Series.)
+Price <span class="price">50 cents</span></p></div>
+
+<p><b>Concrete Monuments, Mausoleums and Burial Vaults.</b> By <span class="smcap">A. A. Houghton</span>.</p>
+
+<div class="blockquot"><p>The molding of concrete monuments to imitate the most expensive cut stone is explained
+in this treatise with working drawings of easily built molds. Cutting inscriptions and designs
+are also fully treated. (No. 6 of Series.) Price <span class="price">50 cents</span></p></div>
+
+<p><b>Molding Concrete Bathtubs, Aquariums and Natatoriums.</b> By <span class="smcap">A. A.
+Houghton</span>.</p>
+
+<div class="blockquot"><p>Simple molds and instruction are given for molding many styles of concrete bathtubs, swimming-pools,
+etc. These molds are easily built and permit rapid and successful work. (No. 7
+of Series.) Price <span class="price">50 cents</span></p></div>
+
+<p><span class='pagenum'><a name="Page_Cat11" id="Page_Cat11">[11]</a></span><b>Concrete
+Bridges, Culverts and Sewers.</b> By <span class="smcap">A. A. Houghton</span>.</p>
+
+<div class="blockquot"><p>A number of ornamental concrete bridges with illustrations of molds are given. A collapsible
+center or core for bridges, culverts and sewers is fully illustrated with detailed instructions
+for building. (No. 8 of Series.) Price <span class="price">50 cents</span></p></div>
+
+<p><b>Constructing Concrete Porches.</b> By <span class="smcap">A. A. Houghton</span>.</p>
+
+<div class="blockquot"><p>A number of designs with working drawings of molds are fully explained so any one can easily
+construct different styles of ornamental concrete porches without the purchase of expensive
+molds. (No. 9 of Series.) Price <span class="price">50 cents</span></p></div>
+
+<p><b>Molding Concrete Flower-Pots, Boxes, Jardinieres, Etc.</b> By <span class="smcap">A. A. Houghton</span>.</p>
+
+<div class="blockquot"><p>The molds for producing many original designs of flower-pots, urns, flower-boxes, jardinieres,
+etc., are fully illustrated and explained, so the worker can easily construct and operate same.
+(No. 10 of Series.) Price <span class="price">50 cents</span></p></div>
+
+<p><b>Molding Concrete Fountains and Lawn Ornaments.</b> By <span class="smcap">A. A. Houghton</span>.</p>
+
+<div class="blockquot"><p>The molding of a number of designs of lawn seats, curbing, hitching posts, pergolas, sun dials
+and other forms of ornamental concrete for the ornamentation of lawns and gardens, is fully
+illustrated and described. (No. 11 of Series.) Price <span class="price">50 cents</span></p></div>
+
+<p><b>Concrete from Sand Molds.</b> By <span class="smcap">A. A. Houghton</span>.</p>
+
+<div class="blockquot"><p>A Practical Work treating on a process which has heretofore been held as a trade secret by
+the few who possessed it, and which will successfully mold every and any class of ornamental
+concrete work. The process of molding concrete with sand molds is of the utmost practical
+value, possessing the manifold advantages of a low cost of molds, the ease and rapidity of
+operation, perfect details to all ornamental designs, density and increased strength of the
+concrete, perfect curing of the work without attention and the easy removal of the molds
+regardless of any undercutting the design may have. 192 pages. Fully illustrated
+Price <span class="price">$2.00</span></p></div>
+
+<p><b>Ornamental Concrete without Molds.</b> By <span class="smcap">A. A. Houghton</span>.</p>
+
+<div class="blockquot"><p>The process for making ornamental concrete without molds has long been held as a secret,
+and now, for the first time, this process is given to the public. The book reveals the secret
+and is the only book published which explains a simple, practical method whereby the concrete
+worker is enabled, by employing wood and metal templates of different designs, to mold
+or model in concrete any Cornice, Archivolt, Column, Pedestal, Base Cap, Urn or Pier in a
+monolithic form&mdash;right upon the job. These may be molded in units or blocks and then built
+up to suit the specifications demanded. This work is fully illustrated, with detailed engravings.
+Price <span class="price">$2.00</span></p></div>
+
+<p><b>Concrete for the Farm and in the Shop.</b> By <span class="smcap">H. Colin Campbell</span>, C.E., E.M.</p>
+
+<div class="blockquot"><p>&#8220;Concrete for the Farm and in the Shop&#8221; is a new book from cover to cover, illustrating and
+describing in plain, simple language many of the numerous applications of concrete within
+the range of the home worker. Among the subjects treated are: Principles of Reinforcing;
+Methods of Protecting Concrete so as to Insure Proper Hardening; Home-made Mixers;
+Mixing by Hand and Machine; Form Construction, Described and Illustrated by Drawings
+and Photographs; Construction of Concrete Walls and Fences; Concrete Fence Posts;
+Concrete Gate Posts; Corner Posts; Clothes Line Posts; Grape Arbor Posts; Tanks;
+Troughs; Cisterns; Hog Wallows; Feeding Floors and Barnyard Pavements; Foundations;
+Well Curbs and Platforms; Indoor Floors; Sidewalks; Steps; Concrete Hotbeds and Cold
+Frames; Concrete Slab Roofs; Walls for Buildings; Repairing Leaks in Tanks and Cisterns;
+and all topics associated with these subjects as bearing upon securing the best results from
+concrete are dwelt upon at sufficient length in plain every-day English so that the inexperienced
+person desiring to undertake a piece of concrete construction can, by following the
+directions set forth in this book, secure 100 per cent. success every time. A number of convenient
+and practical tables for estimating quantities, and some practical examples, are also
+given. (5x7.) 149 pages. 51 illustrations. Price <span class="price">75 cents</span></p></div>
+
+<p><b>Popular Handbook for Cement and Concrete Users.</b> By <span class="smcap">Myron H. Lewis</span>.</p>
+
+<div class="blockquot"><p>This is a concise treatise of the principles and methods employed in the manufacture and use
+of cement in all classes of modern works. The author has brought together in this work all
+the salient matter of interest to the user of concrete and its many diversified products. The
+matter is presented in logical and systematic order, clearly written, fully illustrated and free
+from involved mathematics. Everything of value to the concrete user is given, including
+kinds of cement employed in construction, concrete architecture, inspection and testing,
+waterproofing, coloring and painting, rules, tables, working and cost data. The book comprises
+thirty-three chapters, as follow: Introductory. Kinds of Cement and How They
+are Made. Properties. Testing and Requirements of Hydraulic Cement. Concrete and Its
+Properties. Sand, Broken Stone and Gravel for Concrete. How to Proportion the Materials.
+How to Mix and Place Concrete. Forms of Concrete Construction. The Architectural and
+Artistic Possibilities of Concrete. Concrete Residences. Mortars, Plasters and Stucco,
+and How to Use Them. The Artistic Treatment of Concrete Surfaces. Concrete
+Building<span class='pagenum'><a name="Page_Cat12" id="Page_Cat12">[12]</a></span>
+Blocks. The Making of Ornamental Concrete. Concrete Pipes, Fences, Posts, etc. Essential
+Features and Advantages of Reenforced Concrete. How to Design Reenforced Concrete
+Beams, Slabs and Columns. Explanations of the Methods and Principles in Designing
+Reenforced Concrete, Beams and Slabs. Systems of Reenforcement Employed. Reenforced
+Concrete in Factory and General Building Construction. Concrete in Foundation Work.
+Concrete Retaining Walls, Abutments and Bulkheads. Concrete Arches and Arch Bridges.
+Concrete Beam and Girder Bridges. Concrete in Sewerage and Draining Works. Concrete
+Tanks, Dams and Reservoirs. Concrete Sidewalks, Curbs and Pavements. Concrete in
+Railroad Construction. The Utility of Concrete on the Farm. The Waterproofing of Concrete
+Structures. Grout of Liquid Concrete and Its Use. Inspection of Concrete Work.
+Cost of Concrete Work. Some of the special features of the book are: 1.&mdash;The Attention
+Paid to the Artistic and Architectural Side of Concrete Work. 2.&mdash;The Authoritative Treatment
+of the Problem of Waterproofing Concrete. 3.&mdash;An Excellent Summary of the Rules
+to be Followed in Concrete Construction. 4.&mdash;The Valuable Cost Data and Useful Tables
+given. A valuable Addition to the Library of Every Cement and Concrete User. Price <span class="price">$2.50</span></p>
+
+<h3>WHAT IS SAID OF THIS BOOK:</h3>
+
+<p>&#8220;The field of Concrete Construction is well covered and the matter contained is well within
+the understanding of any person.&#8221;&mdash;<i>Engineering-Contracting.</i></p>
+
+<p>&#8220;Should be on the bookshelves of every contractor, engineer, and architect in the land.&#8221;&mdash;<i>National
+Builder.</i></p></div>
+
+<p><b>Waterproofing Concrete.</b> By <span class="smcap">Myron H. Lewis</span>.</p>
+
+<div class="blockquot"><p>Modern Methods of Waterproofing Concrete and Other Structures. A condensed statement
+of the Principles, Rules, and Precautions to be Observed in Waterproofing and Dampproofing
+Structures and Structural Materials. Paper binding. Illustrated. Price <span class="price">50 cents</span></p></div>
+
+<h2>DICTIONARIES</h2>
+
+<p><b>Aviation Terms, Termes D&#8217;Aviation, English-French, French-English.</b>
+Compiled by Lieuts. <span class="smcap">Victor W. Pag&eacute;</span>, A.S., S.C.U.S.R., and <span class="smcap">Paul Montariol</span>,
+of the French Flying Corps, on duty on Signal Corps Aviation School,
+Mineola, L. I.</p>
+
+<div class="blockquot"><p>The lists contained are confined to essentials, and special folding plates are included to show
+all important airplane parts. The lists are divided in four sections as follows: 1.&mdash;Flying
+Field Terms. 2.&mdash;The Airplane. 3.&mdash;The Engine. 4.&mdash;Tools and Shop Terms.</p>
+
+<p>A complete, well illustrated volume intended to facilitate conversation between English-speaking
+and French aviators. A very valuable book for all who are about to leave for duty overseas.</p>
+
+<p>Approved for publication by Major W. G. Kilner, S.C., U.S.C.O. Signal Corps Aviation School,
+Hazelhurst Field, Mineola, L. I. This book should be in every Aviator&#8217;s and Mechanic&#8217;s Kit
+for ready reference. 128 pages, fully illustrated, with detailed engravings. Price <span class="price">$1.00</span></p></div>
+
+<p><b>Standard Electrical Dictionary.</b> By <span class="smcap">T. O&#8217;Conor Sloane</span>.</p>
+
+<div class="blockquot"><p>An indispensable work to all interested in electrical science. Suitable alike for the student
+and professional. A practical handbook of reference containing definitions of about 5,000
+distinct words, terms and phrases. The definitions are terse and concise; and include every
+term used in electrical science. Recently issued. An entirely new edition. Should be in
+the possession of all who desire to keep abreast with the progress of this branch of science.
+Complete, concise and convenient. 682 pages, 393 illustrations. Price <span class="price">$3.00</span></p></div>
+
+<h2>DIES&mdash;METAL WORK</h2>
+
+<p><b>Dies: Their Construction and Use for the Modern Working of Sheet Metals.</b>
+By <span class="smcap">J. V. Woodworth</span>.</p>
+
+<div class="blockquot"><p>A most useful book, and one which should be in the hands of all engaged in the press working
+of metals; treating on the Designing, Constructing, and Use of Tools, Fixtures and Devices,
+together with the manner in which they should be used in the Power Press, for the cheap and
+rapid production of the great variety of sheet-metal articles now in use. It is designed
+as a guide to the production of sheet-metal parts at the minimum of cost with the
+maximum of output. The hardening and tempering of Press tools and the classes of work
+which may be produced to the best advantage by the use of dies in the power press are fully
+treated. Its 515 illustrations show dies, press fixtures and sheet-metal working devices, the
+descriptions of which are so clear and practical that all metal-working mechanics will be able
+to understand how to design, construct and use them. Many of the dies and press fixtures
+treated were either constructed by the author or under his supervision. Others were built by
+skilful mechanics and are in use in large sheet-metal establishments and machine shops.
+6th Revised and Enlarged Edition. Price <span class="price">$3.00</span></p></div>
+
+<p><span class='pagenum'><a name="Page_Cat13" id="Page_Cat13">[13]</a></span><b>Punches,
+Dies and Tools for Manufacturing in Presses.</b> By <span class="smcap">J. V. Woodworth</span>.</p>
+
+<div class="blockquot"><p>This work is a companion volume to the author&#8217;s elementary work entitled &#8220;Dies: Their
+Construction and Use.&#8221; It does not go into the details of die-making to the extent of the
+author&#8217;s previous book, but gives a comprehensive review of the field of operations carried on
+by presses. A large part of the information given has been drawn from the author&#8217;s personal
+experience. It might well be termed an Encyclopedia of Die-Making, Punch-Making, Die-Sinking,
+Sheet-Metal Working, and Making of Special Tools, Sub-presses, Devices and Mechanical
+Combinations for Punching, Cutting, Bending, Forming, Piercing, Drawing, Compressing
+and Assembling Sheet-Metal Parts, and also Articles of other Materials in Machine Tools.
+2d Edition. Price <span class="price">$4.00</span></p></div>
+
+<p><b>Drop Forging, Die-Sinking and Machine-Forming of Steel.</b> By <span class="smcap">J. V.
+Woodworth</span>.</p>
+
+<div class="blockquot"><p>This is a practical treatise on Modern Shop Practice, Processes, Methods, Machine Tools,
+and Details treating on the Hot and Cold Machine-Forming of Steel and Iron into Finished
+Shapes: together with Tools, Dies, and Machinery involved in the manufacture of Duplicate
+Forgings and Interchangeable Hot and Cold Pressed Parts from Bar and Sheet Metal. This
+book fills a demand of long standing for information regarding drop-forgings, die-sinking and
+machine-forming of steel and the shop practice involved, as it actually exists in the modern
+drop-forging shop. The processes of die-sinking and force-making, which are thoroughly
+described and illustrated in this admirable work, are rarely to be found explained in such a
+clear and concise manner as is here set forth. The process of die-sinking relates to the engraving
+or sinking of the female or lower dies, such as are used for drop-forgings, hot and cold
+machine-forging, swedging, and the press working of metals. The process of force-making
+relates to the engraving or raising of the male or upper dies used in producing the lower dies
+for the press-forming and machine-forging of duplicate parts of metal.</p>
+
+<p>In addition to the arts above mentioned the book contains explicit information regarding the
+drop-forging and hardening plants, designs, conditions, equipment, drop hammers, forging
+machines, etc., machine forging, hydraulic forging, autogenous welding and shop practice.
+The book contains eleven chapters, and the information contained in these chapters is just
+what will prove most valuable to the forged-metal worker. All operations described in the
+work are thoroughly illustrated by means of perspective half-tones and outline sketches of
+the machinery employed. 300 detailed illustrations. Price <span class="price">$2.50</span></p></div>
+
+<h2>DRAWING&mdash;SKETCHING PAPER</h2>
+
+<p><b>Practical Perspective.</b> By <span class="smcap">Richards</span> and <span class="smcap">Colvin</span>.</p>
+
+<div class="blockquot"><p>Shows just how to make all kinds of mechanical drawings in the only practical perspective
+isometric. Makes everything plain, so that any mechanic can understand a sketch or drawing
+in this way. Saves time in the drawing room, and mistakes in the shops. Contains practical
+examples of various classes of work. 4th Edition. Price <span class="price">50 cents</span></p></div>
+
+<p><b>Linear Perspective Self-Taught.</b> By <span class="smcap">Herman T. C. Kraus</span>.</p>
+
+<div class="blockquot"><p>This work gives the theory and practice of linear perspective, as used in architectural, engineering
+and mechanical drawings. Persons taking up the study of the subject by themselves will
+be able, by the use of the instruction given, to readily grasp the subject, and by reasonable
+practice become good perspective draftsmen. The arrangement of the book is good; the plate
+is on the left-hand, while the descriptive text follows on the opposite page, so as to be readily
+referred to. The drawings are on sufficiently large scale to show the work clearly and are
+plainly figured. There is included a self-explanatory chart which gives all information necessary
+for the thorough understanding of perspective. This chart alone is worth many times
+over the price of the book. 2d Revised and Enlarged Edition. Price <span class="price">$2.50</span></p></div>
+
+<p><b>Self-Taught Mechanical Drawing and Elementary Machine Design.</b> By
+<span class="smcap">F. L. Sylvester</span>, M.E., Draftsman, with additions by <span class="smcap">Erik Oberg</span>, associate
+editor of &#8220;Machinery.&#8221;</p>
+
+<div class="blockquot"><p>This is a practical treatise on Mechanical Drawing and Machine Design, comprising the first
+principles of geometric and mechanical drawing, workshop mathematics, mechanics, strength
+of materials and the calculations and design of machine details. The author&#8217;s aim has been
+to adapt this treatise to the requirements of the practical mechanic and young draftsman
+and to present the matter in as clear and concise a manner as possible. To meet the demands
+of this class of students, practically all the important elements of machine design have been
+dealt with, and in addition algebraic formulas have been explained, and the elements of
+trigonometry treated in the manner best suited to the needs of the practical man. The book
+is divided into 20 chapters, and in arranging the material, mechanical drawing, pure and simple,
+has been taken up first, as a thorough understanding of the principles of representing objects
+facilitates the further study of mechanical subjects. This is followed by the mathematics
+necessary for the solution of the problems in machine design which are presented later, and a
+practical introduction to theoretical mechanics and the strength of materials. The various
+elements entering into machine design, such as cams, gears, sprocket-wheels, cone pulleys,
+bolts, screws, couplings, clutches, shafting and fly-wheels, have been treated in such a way
+as to make possible the use of the work as a text-book for a continuous course of study. It
+is easily comprehended and assimilated even by students of limited previous training. 330
+pages, 215 engravings. Price <span class="price">$2.00</span></p></div>
+
+<p><span class='pagenum'><a name="Page_Cat14" id="Page_Cat14">[14]</a></span><b>A New Sketching Paper.</b></p>
+
+<div class="blockquot"><p>A new specially ruled paper to enable you to make sketches or drawings in isometric perspective
+without any figuring or fussing. It is being used for shop details as well as for assembly
+drawings, as it makes one sketch do the work of three, and no workman can help seeing just
+what is wanted.</p>
+
+<table style="margin-left: 0;" summary="table p 14">
+
+<tr>
+<td class="left padr5">Pads of 40 sheets, 6x9 inches.</td>
+<td class="left padr5">Price</td>
+<td class="right"><span class="price">25 cents</span></td>
+</tr>
+
+<tr>
+<td class="left padr5">Pads of 40 sheets, 9x12 inches.</td>
+<td class="left padr5">Price</td>
+<td class="right"><span class="price">50 cents</span></td>
+</tr>
+
+<tr>
+<td class="left padr5">40 sheets, 12x18 inches.</td>
+<td class="left padr5">Price</td>
+<td class="right"><span class="price">$1.00</span></td>
+</tr>
+
+</table>
+</div>
+
+<h2>ELECTRICITY</h2>
+
+<p><b>Arithmetic of Electricity.</b> By Prof. <span class="smcap">T. O&#8217;Conor Sloane</span>.</p>
+
+<div class="blockquot"><p>A practical treatise on electrical calculations of all kinds reduced to a series of rules, all of the
+simplest forms, and involving only ordinary arithmetic; each rule illustrated by one or more
+practical problems, with detailed solution of each one. This book is classed among the most
+useful works published on the science of electricity, covering as it does the mathematics of
+electricity in a manner that will attract the attention of those who are not familiar with algebraical
+formulas. 20th Edition. 160 pages. Price <span class="price">$1.00</span></p></div>
+
+<p><b>Commutator Construction.</b> By <span class="smcap">Wm. Baxter, Jr.</span></p>
+
+<div class="blockquot"><p>The business end of any dynamo or motor of the direct current type is the commutator. This
+book goes into the designing, building, and maintenance of commutators, shows how to locate
+troubles and how to remedy them; everyone who fusses with dynamos needs this. 4th Edition.
+Price <span class="price">25 cents</span></p></div>
+
+<p><b>Dynamo Building for Amateurs, or How to Construct a Fifty-Watt Dynamo.</b>
+By <span class="smcap">Arthur J. Weed</span>, Member of N. Y. Electrical Society.</p>
+
+<div class="blockquot"><p>A practical treatise showing in detail the construction of a small dynamo or motor, the entire
+machine work of which can be done on a small foot lathe. Dimensioned working drawings
+are given for each piece of machine work, and each operation is clearly described. This
+machine, when used as a dynamo, has an output of fifty watts; when used as a motor it will
+drive a small drill press or lathe. It can be used to drive a sewing machine on any and all
+ordinary work. The book is illustrated with more than sixty original engravings, showing the
+actual construction of the different parts. Among the contents are chapters on: 1. Fifty-Watt
+Dynamo. 2. Side Bearing Rods. 3. Field Punching. 4. Bearings. 5. Commutator. 6.
+Pulley. 7. Brush Holders. 8. Connection Board. 9. Armature Shaft. 10. Armature.
+11. Armature Winding. 12. Field Winding. 13. Connecting and starting.</p>
+
+<table style="margin-left: 0;" summary="Table p 14">
+
+<tr>
+<td class="left padr5">Paper.</td>
+<td class="left padr5">Price</td>
+<td class="right"><span class="price">50 Cents</span></td>
+</tr>
+
+<tr>
+<td class="left padr5">Cloth.</td>
+<td class="left padr5">Price</td>
+<td class="right"><span class="price">$1.00</span></td>
+</tr>
+
+</table>
+</div>
+
+<p><b>Electric Bells.</b> By <span class="smcap">M. B. Sleeper</span>.</p>
+
+<div class="blockquot"><p>A complete treatise for the practical worker in Installing, Operating and Testing Bell Circuits,
+Burglar Alarms, Thermostats, and other apparatus used with Electric Bells.</p>
+
+<p>Both the electrician and the experimenter will find in this book new material which is essential
+in their work. Tools, bells, batteries, unusual circuits, burglar alarms, annunciator systems,
+thermostats, circuit breakers, time alarms, and other apparatus used in bell circuits are described
+from the standpoints of their application, construction and repair. The detailed
+instruction for building the apparatus will appeal to the experimenter particularly.</p>
+
+<p>The practical worker will find the chapter on Wiring, Calculation of Wire Sizes and Magnet
+Winding, Upkeep of Systems, and the Location of Faults, of the greatest value in their work.
+Among the chapters are: Tools and Materials for Bell Work; How and Why Bell Work;
+Batteries for Small Installations; Making Bells and Push Buttons; Wiring Bell Systems;
+Construction of Annunciators and Signals; Burglary Alarms and Auxiliary Apparatus; More
+Elaborate Bell Systems; Finding Faults and Remedying Them. 124 pages, fully illustrated.
+Price <span class="price">50 cents</span></p></div>
+
+<p><b>Electric Lighting and Heating Pocket Book.</b> By <span class="smcap">Sydney F. Walker</span>.</p>
+
+<div class="blockquot"><p>This book puts in convenient form useful information regarding the apparatus which is likely
+to be attached to the mains of an electrical company. Tables of units and equivalents are included
+and useful electrical laws and formulas are stated. 438 pages, 300 engravings. Bound
+in leather. Pocket book form. Price <span class="price">$3.00</span></p></div>
+
+<p><b>Electric Wiring, Diagrams and Switchboards.</b> By <span class="smcap">Newton Harrison</span>, with
+additions by <span class="smcap">Thomas Poppe</span>.</p>
+
+<div class="blockquot"><p>A thoroughly practical treatise covering the subject of Electric Wiring in all its branches,
+deluding explanations and diagrams which are thoroughly explicit and greatly simplify the
+subject. Practical every-day problems in wiring are presented and the method of obtaining
+intelligent results clearly shown. Only arithmetic is used. Ohm&#8217;s law is given a simple
+explanation with reference to wiring for direct and alternating currents. The fundamental
+principle of drop of potential in circuits is shown with its various applications. The
+simple circuit is developed with the position of mains, feeders and branches; their treatment<span
+class='pagenum' style="font-size: 100%;"><a name="Page_Cat15" id="Page_Cat15">[15]</a></span>
+as a part of a wiring plan and their employment in house wiring clearly illustrated. Some
+simple facts about testing are included in connection with the wiring. Molding and conduit
+work are given careful consideration; and switchboards are systematically treated, built up
+and illustrated, showing the purpose they serve, for connection with the circuits, and to shunt
+and compound wound machines. The simple principles of switchboard construction, the
+development of the switchboard, the connections of the various instruments, including the
+lightning arrester, are also plainly set forth.</p>
+
+<p>Alternating current wiring is treated, with explanations of the power factor, conditions calling
+for various sizes of wire, and a simple way of obtaining the sizes for single-phase, two-phase
+and three-phase circuits. This is the only complete work issued showing and telling you what
+you should know about direct and alternating current wiring. It is a ready reference. The
+work is free from advanced technicalities and mathematics, arithmetic being used throughout.
+It is in every respect a handy, well-written, instructive, comprehensive volume on wiring
+for the wireman, foreman, contractor, or electrician. 2nd Revised Edition. 303 pages, 130
+illustrations. Price <span class="price">$1.50</span></p></div>
+
+<p><b>Electric Furnaces and their Industrial Applications.</b> By <span class="smcap">J. Wright</span>.</p>
+
+<div class="blockquot"><p>This is a book which will prove of interest to many classes of people: the manufacturer who
+desires to know what product can be manufactured successfully in the electric furnace, the
+chemist who wishes to post himself on the electro-chemistry, and the student of science who
+merely looks into the subject from curiosity. New, Revised and Enlarged Edition. 320
+pages. Fully illustrated, cloth. Price <span class="price">$3.00</span></p></div>
+
+<p><b>Electric Toy Making, Dynamo Building, and Electric Motor Construction.</b>
+By Prof. <span class="smcap">T. O&#8217;Conor Sloane</span>.</p>
+
+<div class="blockquot"><p>This work treats of the making at home of electrical toys, electrical apparatus, motors, dynamos,
+and instruments in general, and is designed to bring within the reach of young and old the
+manufacture of genuine and useful electrical appliances. The work is especially designed for
+amateurs and young folks.</p>
+
+<p>Thousands of our young people are daily experimenting, and busily engaged in making electrical
+toys and apparatus of various kinds. The present work is just what is wanted to give
+the much needed information in a plain, practical manner, with illustrations to make easy
+the carrying out of the work. 20th Edition. Price <span class="price">$1.00</span></p></div>
+
+<p><b>Practical Electricity.</b> By Prof. <span class="smcap">T. O&#8217;Conor Sloane</span>.</p>
+
+<div class="blockquot"><p>This work of 768 pages was previously known as Sloane&#8217;s Electricians&#8217; Hand Book, and is
+intended for the practical electrician who has to make things go. The entire field of electricity
+is covered within its pages. Among some of the subjects treated are: The Theory of the
+Electric Current and Circuit, Electro-Chemistry, Primary Batteries, Storage Batteries,
+Generation and Utilization of Electric Powers, Alternating Current, Armature Winding,
+Dynamos and Motors, Motor Generators, Operation of the Central Station Switchboards,
+Safety Appliances, Distribution of Electric Light and Power, Street Mains, Transformers,
+Arc and Incandescent Lighting, Electric Measurements, Photometry, Electric Railways,
+Telephony, Bell-Wiring, Electric-Plating, Electric Heating, Wireless Telegraphy, etc. It
+contains no useless theory; everything is to the point. It teaches you just what you want
+to know about electricity. It is the standard work published on the subject. Forty-one
+chapters, 556 engravings. Price <span class="price">$2.50</span></p></div>
+
+<p><b>Electricity Simplified.</b> By Prof. <span class="smcap">T. O&#8217;Conor Sloane</span>.</p>
+
+<div class="blockquot"><p>The object of &#8220;Electricity Simplified&#8221; is to make the subject as plain as possible and
+to show what the modern conception of electricity is; to show how two plates of different
+metal, immersed in acid, can send a message around the globe; to explain how a bundle of
+copper wire rotated by a steam engine can be the agent in lighting our streets; to tell what the
+volt, ohm and ampere are, and what high and low tension mean; and to answer the questions
+that perpetually arise in the mind in this age of electricity. 13th Edition. 172 pages. Illustrated.
+Price <span class="price">$1.00</span></p></div>
+
+<p><b>House Wiring.</b> By <span class="smcap">Thomas W. Poppe</span>.</p>
+
+<div class="blockquot"><p>This work describes and illustrates the actual installation of Electric Light Wiring, the manner
+in which the work should be done, and the method of doing it. The book can be conveniently
+carried in the pocket. It is intended for the Electrician, Helper and Apprentice.
+It solves all Wiring Problems and contains nothing that conflicts with the rulings of the
+National Board of Fire Underwriters. It gives just the information essential to the Successful
+Wiring of a Building. Among the subjects treated are: Locating the Meter. Panel-Boards.
+Switches. Plug Receptacles. Brackets. Ceiling Fixtures. The Meter Connections.
+The Feed Wires. The Steel Armored Cable System. The Flexible Steel Conduit
+System. The Ridig Conduit System. A digest of the National Board of Fire Underwriters&#8217;
+rules relating to metallic wiring systems. Various switching arrangements explained and
+diagrammed. The easiest method of testing the Three- and Four-way circuits explained.
+The grounding of all metallic wiring systems and the reason for doing so shown and explained.
+The insulation of the metal parts of lamp fixtures and the reason for the same described and
+illustrated. 125 pages. 2nd Edition, revised and enlarged. Fully illustrated. Flexible
+cloth. Price <span class="price">50 cents</span></p></div>
+
+<p><span class='pagenum'><a name="Page_Cat16" id="Page_Cat16">[16]</a></span><b>How
+to Become a Successful Electrician.</b> By Prof. <span class="smcap">T. O&#8217;Conor Sloane</span>.</p>
+
+<div class="blockquot"><p>Every young man who wishes to become a successful electrician should read this book. It
+tells in simple language the surest and easiest way to become a successful electrician. The
+studies to be followed, methods of work, field of operation and the requirements of the successful
+electrician are pointed out and fully explained. Every young engineer will find this an
+excellent stepping stone to more advanced works on electricity which he must master before
+success can be attained. Many young men become discouraged at the very outstart by attempting
+to read and study books that are far beyond their comprehension. This book serves
+as the connecting link between the rudiments taught in the public schools and the real study
+of electricity. It is interesting from cover to cover. 18th Revised Edition, just issued. 205
+pages. Illustrated. Price <span class="price">$1.00</span></p></div>
+
+<p><b>Management of Dynamos.</b> By <span class="smcap">Lummis-Paterson</span>.</p>
+
+<div class="blockquot"><p>A handbook of theory and practice. This work is arranged in three parts. The first part
+covers the elementary theory of the dynamo. The second part, the construction and action
+of the different classes of dynamos in common use are described; while the third part relates
+to such matters as affect the practical management and working of dynamos and motors.
+4th Edition. 292 pages, 117 illustrations. Price <span class="price">$1.50</span></p></div>
+
+<p><b>Standard Electrical Dictionary.</b> By <span class="smcap">T. O&#8217;Conor Sloane</span>.</p>
+
+<div class="blockquot"><p>An indispensable work to all interested in electrical science. Suitable alike for the student
+and professional. A practical handbook of reference containing definitions of about 5,000
+distinct words, terms and phrases. The definitions are terse and concise and include every
+term used in electrical science. Recently issued. An entirely new edition. Should be in the
+possession of all who desire to keep abreast with the progress of this branch of science. In
+its arrangement and typography the book is very convenient. The word or term defined is
+printed in black-faced type, which readily catches the eye, while the body of the page is in
+smaller but distinct type. The definitions are well worded, and so as to be understood by the
+non-technical reader. The general plan seems to be to give an exact, concise definition, and
+then amplify and explain in a more popular way. Synonyms are also given, and references
+to other words and phrases are made. A very complete and accurate index of fifty pages
+is at the end of the volume; and as this index contains all synonyms, and as all phrases are
+indexed in every reasonable combination of words, reference to the proper place in the body
+of the book is readily made. It is difficult to decide how far a book of this character is to
+keep the dictionary form, and to what extent it may assume the encyclopedia form. For
+some purposes, concise, exactly worded definitions are needed; for other purposes, more
+extended descriptions are required. This book seeks to satisfy both demands, and does it
+with considerable success. 682 pages, 393 illustrations. 12th Edition.
+Price <span class="price">$3.00</span></p></div>
+
+<p><b>Storage Batteries Simplified.</b> By <span class="smcap">Victor W. Pag&eacute;</span>, M.E.</p>
+
+<div class="blockquot"><p>A complete treatise on storage battery operating principles, repairs and applications.
+The greatly increasing application of storage batteries in modern engineering and mechanical
+work has created a demand for a book that will consider this subject completely and exclusively.
+This is the most thorough and authoritative treatise ever published on this subject.
+It is written in easily understandable, non-technical language so that any one may grasp
+the basic principles of storage battery action as well as their practical industrial applications.
+All electric and gasoline automobiles use storage batteries. Every automobile repairman,
+dealer or salesman should have a good knowledge of maintenance and repair of these important
+elements of the motor car mechanism. This book not only tells how to charge, care for
+and rebuild storage batteries but also outlines all the industrial uses. Learn how they run
+street cars, locomotives and factory trucks. Get an understanding of the important functions
+they perform in submarine boats, isolated lighting plants, railway switch and signal systems,
+marine applications, etc. This book tells how they are used in central station standby service,
+for starting automobile motors and in ignition systems. Every practical use of the modern
+storage battery is outlined in this treatise. 320 pages, fully illustrated. Price <span class="price">$1.50</span></p></div>
+
+<p><b>Switchboards.</b> By <span class="smcap">William Baxter, Jr.</span></p>
+
+<div class="blockquot"><p>This book appeals to every engineer and electrician who wants to know the practical side
+of things. It takes up all sorts and conditions of dynamos, connections and circuits, and
+shows by diagram and illustration just how the switchboard should be connected. Includes
+direct and alternating current boards, also those for arc lighting, incandescent and power
+circuits. Special treatment on high voltage boards for power transmission. 2nd Edition.
+190 pages, Illustrated. Price <span class="price">$1.50</span></p></div>
+
+<p><b>Telephone Construction, Installation, Wiring, Operation and Maintenance.</b>
+By <span class="smcap">W. H. Radcliffe</span> and <span class="smcap">H. C. Cushing</span>.</p>
+
+<div class="blockquot"><p>This book is intended for the amateur, the wireman, or the engineer who desires to establish
+a means of telephonic communication between the rooms of his home, office, or shop. It
+deals only with such things as may be of use to him rather than with theories.</p>
+
+<p>Gives the principles of construction and operation of both the Bell and Independent instruments;
+approved methods of installing and wiring them; the means of protecting them
+from lightning and abnormal currents; their connection together for operation as series or
+bridging stations; and rules for their inspection and maintenance. Line wiring and the wiring
+and operation of special telephone systems are also treated. Intricate mathematics are
+avoided, and all apparatus, circuits and systems are thoroughly described. The appendix<span class='pagenum'
+style="font-size: 100%;"><a name="Page_Cat17" id="Page_Cat17">[17]</a></span>
+contains definitions of units and terms used in the text. Selected wiring tables, which are very
+helpful, are also included. Among the subjects treated are Construction, Operation, and
+Installation of Telephone Instruments; Inspection and Maintenance of Telephone Instruments;
+Telephone Line Wiring; Testing Telephone Line Wires and Cables; Wiring and
+Operation of Special Telephone Systems, etc. 2nd Edition, Revised and Enlarged. 223
+pages, 154 illustrations. Price <span class="price">$1.00</span></p></div>
+
+<p><b>Wireless Telegraphy and Telephony Simply Explained.</b> By <span class="smcap">Alfred P.
+Morgan</span>.</p>
+
+<div class="blockquot"><p>This is undoubtedly one of the most complete and comprehensible treatises on the subject
+ever published, and a close study of its pages will enable one to master all the details of the
+wireless transmission of messages. The author has filled a long-felt want and has succeeded
+in furnishing a lucid, comprehensible explanation in simple language of the theory and practice
+of wireless telegraphy and telephony.</p>
+
+<p>Among the contents are: Introductory; Wireless Transmission and Reception&mdash;The Aerial
+System, Earth Connections&mdash;The Transmitting Apparatus, Spark Coils and Transformers,
+Condensers, Helixes, Spark Gaps, Anchor Gaps, Aerial Switches&mdash;The Receiving Apparatus,
+Detectors, etc.&mdash;Tuning and Coupling, Tuning Coils, Loose Couplers, Variable Condensers,
+Directive Wave Systems&mdash;Miscellaneous Apparatus, Telephone Receivers, Range of Stations,
+Static Interference&mdash;Wireless Telephones, Sound and Sound Waves, The Vocal Cords and
+Ear&mdash;Wireless Telephone, How Sounds Are Changed into Electric Waves&mdash;Wireless Telephones,
+The Apparatus&mdash;Summary. 154 pages, 156 engravings. Price <span class="price">$1.00</span></p></div>
+
+<p><b>Wiring a House.</b> By <span class="smcap">Herbert Pratt</span>.</p>
+
+<div class="blockquot"><p>Shows a house already built; tells just how to start about wiring it; where to begin; what
+wire to use; how to run it according to Insurance Rules; in fact, just the information you
+need. Directions apply equally to a shop. 4th Edition. Price <span class="price">25 cents</span></p></div>
+
+<h2>FACTORY MANAGEMENT, ETC.</h2>
+
+<p><b>Modern Machine Shop Construction, Equipment and Management.</b> By
+<span class="smcap">O. E. Perrigo</span>, M.E.</p>
+
+<div class="blockquot"><p>The only work published that describes the modern machine shop or manufacturing plant
+from the time the grass is growing on the site intended for it until the finished product is
+shipped. By a careful study of its thirty-two chapters the practical man may economically
+build, efficiently equip, and successfully manage the modern machine shop or manufacturing
+establishment. Just the book needed by those contemplating the erection of modern shop
+buildings, the rebuilding and reorganization of old ones, or the introduction of modern shop
+methods, time and cost systems. It is a book written and illustrated by a practical shop
+man for practical shop men who are too busy to read <i>theories</i> and want <i>facts</i>. It is the most
+complete all-around book of its kind ever published. It is a practical book for practical men,
+from the apprentice in the shop to the president in the office. It minutely describes and illustrates
+the most simple and yet the most efficient time and cost system yet devised. 2nd
+Revised and Enlarged Edition, just issued. 384 pages, 219 illustrations. Price <span class="price">$5.00</span></p></div>
+
+<h2>FUEL</h2>
+
+<p><b>Combustion of Coal and the Prevention of Smoke.</b> By <span class="smcap">Wm. M. Barr</span>.</p>
+
+<div class="blockquot"><p>This book has been prepared with special reference to the generation of heat by the combustion
+of the common fuels found in the United States, and deals particularly with the conditions
+necessary to the economic and smokeless combustion of bituminous coals in Stationary
+and Locomotive Steam Boilers.</p>
+
+<p>The presentation of this important subject is systematic and progressive. The arrangement
+of the book is in a series of practical questions to which are appended accurate answers, which
+describe in language, free from technicalities, the several processes involved in the furnace
+combustion of American fuels; it clearly states the essential requisites for perfect combustion,
+and points out the best methods for furnace construction for obtaining the greatest quantity
+of heat from any given quality of coal. Nearly 350 pages, fully illustrated. Price <span class="price">$1.00</span></p></div>
+
+<p><b>Smoke Prevention and Fuel Economy.</b> By <span class="smcap">Booth</span> and <span class="smcap">Kershaw</span>.</p>
+
+<div class="blockquot"><p>A complete treatise for all interested in smoke prevention and combustion, being based on
+the German work of Ernst Schmatolla, but it is more than a mere translation of the German
+treatise, much being added. The authors show as briefly as possible the principles of fuel
+combustion, the methods which have been and are at present in use, as well as the proper
+scientific methods for obtaining all the energy in the coal and burning it without smoke.
+Considerable space is also given to the examination of the waste gases, and several of the
+representative English and American mechanical stoker and similar appliances are described.
+The losses carried away in the waste gases are thoroughly analyzed and discussed in the Appendix,
+and abstracts are also here given of various patents on combustion apparatus. The
+book is complete and contains much of value to all who have charge of large plants. 194 pages.
+Illustrated. Price <span class="price">$2.50</span></p></div>
+
+<p class='pagenum'><a name="Page_Cat18" id="Page_Cat18">[18]</a></p>
+
+<h2>GAS ENGINES AND GAS</h2>
+
+<p><b>Gas, Gasoline and Oil Engines.</b> By <span class="smcap">Gardner D. Hiscox</span>. Revised by
+<span class="smcap">Victor W. Pag&eacute;</span>, M.E.</p>
+
+<div class="blockquot"><p>Just issued New 1918 Edition, Revised and Enlarged. Every user of a gas engine needs
+this book. Simple, instructive and right up-to-date. The only complete work on the subject.
+Tells all about internal combustion engineering, treating exhaustively on the design, construction
+and practical application of all forms of gas, gasoline, kerosene and crude petroleum-oil
+engines. Describes minutely all auxiliary systems, such as lubrication, carburetion and
+ignition. Considers the theory and management of all forms of explosive motors for stationary
+and marine work, automobiles, aeroplanes and motor-cycles. Includes also Producer
+Gas and Its Production. Invaluable instructions for all students, gas-engine owners, gas-engineers,
+patent experts, designers, mechanics, draftsmen and all having to do with the
+modern power. Illustrated by over 400 engravings, many specially made from engineering
+drawings, all in correct proportion. 650 pages, 435 engravings. Price <b>$2.50 net</b></p></div>
+
+<p><b>The Gasoline Engine on the Farm: Its Operation, Repair and Uses.</b> By
+<span class="smcap">Xeno W. Putnam</span>.</p>
+
+<div class="blockquot"><p>This is a practical treatise on the Gasoline and Kerosene Engine intended for the man who
+wants to know just how to manage his engine and how to apply it to all kinds of farm work
+to the best advantage.</p>
+
+<p>This book abounds with hints and helps for the farm and suggestions for the home and house-wife.
+There is so much of value in this book that it is impossible to adequately describe it
+in such small space. Suffice to say that it is the kind of a book every farmer will appreciate
+and every farm home ought to have. Includes selecting the most suitable engine for farm
+work, its most convenient and efficient installation, with chapters on troubles, their remedies,
+and how to avoid them. The care and management of the farm tractor in plowing, harrowing,
+harvesting and road grading are fully covered; also plain directions are given for handling
+the tractor on the road. Special attention is given to relieving farm life of its drudgery by
+applying power to the disagreeable small tasks which must otherwise be done by hand. Many
+home made contrivances for cutting wood, supplying kitchen, garden, and barn with water,
+loading, hauling and unloading hay, delivering grain to the bins or the feed trough are included;
+also full directions for making the engine milk the cows, churn, wash, sweep the
+house and clean the windows, etc. Very fully illustrated with drawings of working parts and
+cuts showing Stationary, Portable and Tractor Engines doing all kinds of farm work. All
+money-making farms utilize power. Learn how to utilize power by reading the pages of this
+book. It is an aid to the result getter, invaluable to the up-to-date farmer, student, blacksmith,
+implement dealer and, in fact, all who can apply practical knowledge of stationary
+gasoline engines or gas tractors to advantage. 530 pages. Nearly 180 engravings. Price <span class="price">$2.00</span></p>
+
+<h3>WHAT IS SAID OF THIS BOOK:</h3>
+
+<p>&#8220;Am much pleased with the book and find it to be very complete and up-to-date. I will
+heartily recommend it to students and farmers whom I think would stand in need of such a
+work, as I think it is an exceptionally good one.&#8221;&mdash;<i>N. S. Gardiner</i>, Prof. in Charge, Clemson
+Agr. College of S. C.; Dept. of Agri. and Agri. Exp. Station, Clemson College, S. C.</p>
+
+<p>&#8220;I feel that Mr. Putnam&#8217;s book covers the main points which a farmer should know.&#8221;&mdash;<i>R. T.
+Burdick</i>, Instructor in Agronomy, University of Vermont, Burlington, Vt.</p></div>
+
+<p><b>Gasoline Engines: Their Operation, Use and Care.</b> By <span class="smcap">A. Hyatt Verrill</span>.</p>
+
+<div class="blockquot"><p>The simplest, latest and most comprehensive popular work published on Gasoline Engines,
+describing what the Gasoline Engine is; its construction and operation; how to install it;
+how to select it; how to use it and how to remedy troubles encountered. Intended for Owners,
+Operators and Users of Gasoline Motors of all kinds. This work fully describes and illustrates the
+various types of Gasoline Engines used in Motor Boats, Motor Vehicles and Stationary Work.
+The parts, accessories and appliances are described with chapters on ignition, fuel, lubrication,
+operation and engine troubles. Special attention is given to the care, operation and repair
+of motors, with useful hints and suggestions on emergency repairs and makeshifts. A complete
+glossary of technical terms and an alphabetically arranged table of troubles and their
+symptoms form most valuable and unique features of this manual. Nearly every illustration
+in the book is original, having been made by the author. Every page is full of interest and
+value. A book which you cannot afford to be without. 275 pages, 152 specially made
+engravings. Price <span class="price">$1.50</span></p></div>
+
+<p><b>Gas Engine Construction, or How to Build a Half-horsepower Gas Engine.</b>
+By <span class="smcap">Parsell</span> and <span class="smcap">Weed</span>.</p>
+
+<div class="blockquot"><p>A practical treatise of 300 pages describing the theory and principles of the action of Gas
+Engines of various types and the design and construction of a half-horsepower Gas Engine,
+with illustrations of the work in actual progress, together with the dimensioned working drawings,
+giving clearly the sizes of the various details; for the student, the scientific investigator,
+and the amateur mechanic. This book treats of the subject more from the standpoint of
+practice than that of theory. The principles of operation of Gas Engines are clearly and
+simply described, and then the actual construction of a half-horsepower engine is taken up,
+step by step, showing in detail the making of the Gas Engine. 3rd Edition. 300 pages.
+Price <span class="price">$2.50</span></p></div>
+
+<p><span class='pagenum'><a name="Page_Cat19" id="Page_Cat19">[19]</a></span><b>How
+to Run and Install Two- and Four-Cycle Marine Gasoline Engines.</b>
+By <span class="smcap">C. Von Culin</span>.</p>
+
+<div class="blockquot"><p>Revised and enlarged edition just issued. The object of this little book is to furnish a pocket
+instructor for the beginner, the busy man who uses an engine for pleasure or profit, but who
+does not have the time or inclination for a technical book, but simply to thoroughly understand
+how to properly operate, install and care for his own engine. The index refers to each
+trouble, remedy, and subject alphabetically. Being a quick reference to find the cause, remedy
+and prevention for troubles, and to become an expert with his own engine. Pocket size.
+Paper binding. Price <span class="price">25 cents</span></p></div>
+
+<p><b>Modern Gas Engines and Producer Gas Plants.</b> By <span class="smcap">R. E. Mathot</span>.</p>
+
+<div class="blockquot"><p>A guide for the gas engine designer, user, and engineer in the construction, selection, purchase,
+installation, operation, and maintenance of gas engines. More than one book on gas engines
+has been written, but not one has thus far even encroached on the field covered by this book.
+Above all, Mr. Mathot&#8217;s work is a practical guide. Recognizing the need of a volume that
+would assist the gas engine user in understanding thoroughly the motor upon which he depends
+for power, the author has discussed his subject without the help of any mathematics and without
+elaborate theoretical explanations. Every part of the gas engine is described in detail,
+tersely, clearly, with a thorough understanding of the requirements of the mechanic. Helpful
+suggestions as to the purchase of an engine, its installation, care, and operation, form a
+most valuable feature of the work. 320 pages, 175 detailed illustrations. Price <span class="price">$2.50</span></p></div>
+
+<p><b>The Modern Gas Tractor.</b> By <span class="smcap">Victor W. Pag&eacute;</span>, M. E.</p>
+
+<div class="blockquot"><p>A complete treatise describing all types and sizes of gasoline, kerosene and oil tractors. Considers
+design and construction exhaustively, gives complete instructions for care, operation and
+repair, outlines all practical applications on the road and in the field. The best and latest
+work on farm tractors and tractor power plants. A work needed by farmers, students, blacksmiths,
+mechanics, salesmen, implement dealers, designers and engineers. 2nd Edition, Revised.
+504 pages, 228 illustrations, 3 folding plates. Price <span class="price">$2.00</span></p></div>
+
+<h2>GEARING AND CAMS</h2>
+
+<p><b>Bevel Gear Tables.</b> By <span class="smcap">D. Ag. Engstrom</span>.</p>
+
+<div class="blockquot"><p>A book that will at once commend itself to mechanics and draftsmen. Does away with all
+the trigonometry and fancy figuring on bevel gears, and makes it easy for anyone to lay them
+out or make them just right. There are 36 full-page tables that show every necessary dimension
+for all sizes or combinations you&#8217;re apt to need. No puzzling, figuring or guessing. Gives
+placing distance, all the angles (including cutting angles), and the correct cutter to use. A
+copy of this prepares you for anything in the bevel-gear line. 3rd Edition. 66 pages.
+Price <span class="price">$1.00</span></p></div>
+
+<p><b>Change Gear Devices.</b> By <span class="smcap">Oscar E. Perrigo</span>.</p>
+
+<div class="blockquot"><p>A practical book for every designer, draftsman, and mechanic interested in the invention and
+development of the devices for feed changes on the different machines requiring such mechanism.
+All the necessary information on this subject is taken up, analyzed, classified, sifted, and concentrated
+for the use of busy men who have not the time to go through the masses of irrelevant
+matter with which such a subject is usually encumbered and select such information as will
+be useful to them.</p>
+
+<p>It shows just what has been done, how it has been done, when it was done, and who did it.
+It saves time in hunting up patent records and re-inventing old ideas. 88 pages. 3rd Edition.
+Price <span class="price">$1.00</span></p></div>
+
+<p><b>Drafting of Cams.</b> By <span class="smcap">Louis Rouillion</span>.</p>
+
+<div class="blockquot"><p>The laying out of cams is a serious problem unless you know how to go at it right. This puts
+you on the right road for practically any kind of cam you are likely to run up against. 3rd
+Edition. Price <span class="price">25 Cents</span></p></div>
+
+<h2>HYDRAULICS</h2>
+
+<p><b>Hydraulic Engineering.</b> By <span class="smcap">Gardner D. Hiscox</span>.</p>
+
+<div class="blockquot"><p>A treatise on the properties, power, and resources of water for all purposes. Including the
+measurement of streams, the flow of water in pipes or conduits; the horsepower of falling water,
+turbine and impact water-wheels, wave motors, centrifugal, reciprocating and air-lift pumps.
+With 300 figures and diagrams and 36 practical tables. All who are interested in water-works
+development will find this book a useful one, because it is an entirely practical treatise upon
+a subject of present importance and cannot fail in having a far-reaching influence, and for this
+reason should have a place in the working library of every engineer. Among the subjects
+treated are: Historical Hydraulics; Properties of Water; Measurement of the Flow of Streams;<span
+class='pagenum' style="font-size: 100%;"><a name="Page_Cat20" id="Page_Cat20">[20]</a></span>
+Flow from Sub-surface Orifices and Nozzles; Flow of Water in Pipes; Siphons of Various
+Kinds; Dams and Great Storage Reservoirs; City and Town Water Supply; Wells and Their
+Reinforcement; Air-lift Methods of Raising Water; Artesian Wells; Irrigation of Arid Districts;
+Water Power; Water Wheels; Pumps and Pumping Machinery; Reciprocating Pumps;
+Hydraulic Power Transmission; Hydraulic Mining; Canals; Ditches; Conduits and Pipe
+Lines; Marine Hydraulics; Tidal and Sea Wave Power, etc. 320 pages. Price <span class="price">$4.00</span></p></div>
+
+<h2>ICE AND REFRIGERATION</h2>
+
+<p><b>Pocketbook of Refrigeration and Ice Making.</b> By <span class="smcap">A. J. Wallis-Taylor</span>.</p>
+
+<div class="blockquot"><p>This is one of the latest and most comprehensive reference books published on the subject of
+refrigeration and cold storage. It explains the properties and refrigerating effect of the different
+fluids in use, the management of refrigerating machinery and the construction and insulation
+of cold rooms with their required pipe surface for different degrees of cold; freezing
+mixtures and non-freezing brines, temperatures of cold rooms for all kinds of provisions, cold
+storage charges for all classes of goods, ice making and storage of ice, data and memoranda
+for constant reference by refrigerating engineers, with nearly one hundred tables containing
+valuable references to every fact and condition required in the installment and operation of a
+refrigerating plant. New edition just published. Price <span class="price">$1.50</span></p></div>
+
+<h2>INVENTIONS&mdash;PATENTS</h2>
+
+<p><b>Inventors&#8217; Manual: How to Make a Patent Pay.</b></p>
+
+<div class="blockquot"><p>This is a book designed as a guide to inventors in perfecting their inventions, taking out their
+patents and disposing of them. It is not in any sense a Patent Solicitor&#8217;s Circular nor a Patent
+Broker&#8217;s Advertisement. No advertisements of any description appear in the work. It is a
+book containing a quarter of a century&#8217;s experience of a successful inventor, together with
+notes based upon the experience of many other inventors.</p>
+
+<p>Among the subjects treated in this work are: How to Invent. How to Secure a Good Patent.
+Value of Good Invention. How to Exhibit an Invention. How to Interest Capital. How
+to Estimate the Value of a Patent. Value of Design Patents. Value of Foreign Patents.
+Value of Small Inventions. Advice on Selling Patents. Advice on the Formation of Stock
+Companies. Advice on the Formation of Limited Liability Companies. Advice on Disposing
+of Old Patents. Advice as to Patent Attorneys. Advice as to Selling Agents. Forms of
+Assignments. License and Contracts. State Laws Concerning Patent Rights. 1900 Census
+of the United States by Counts of Over 10,000 Population. Revised Edition. 120 pages.
+Price <span class="price">$1.00</span></p></div>
+
+<h2>KNOTS</h2>
+
+<p><b>Knots, Splices and Rope Work.</b> By <span class="smcap">A. Hyatt Verrill</span>.</p>
+
+<div class="blockquot"><p>This is a practical book giving complete and simple directions for making all the most useful
+and ornamental knots in common use, with chapters on Splicing, Pointing, Seizing, Serving,
+etc. This book is fully illustrated with 154 original engravings, which show how each knot,
+tie or splice is formed, and its appearance when finished. The book will be found of the greatest
+value to Campers, Yachtsmen, Travelers, Boy Scouts, in fact, to anyone having occasion to
+use or handle rope or knots for any purpose. The book is thoroughly reliable and practical,
+and is not only a guide, but a teacher. It is the standard work on the subject. Among the
+contents are: 1. Cordage, Kinds of Rope. Construction of Rope, Parts of Rope Cable and
+Bolt Rope. Strength of Rope, Weight of Rope. 2. Simple Knots and Bends. Terms Used
+in Handling Rope. Seizing Rope. 3. Ties and Hitches. 4. Noose, Loops and Mooring
+Knots. 5. Shortenings, Grommets and Salvages. 6. Lashings, Seizings and Splices. 7.
+Fancy Knots and Rope Work. 128 pages, 150 original engravings. 2nd Revised Edition.
+Price <span class="price">75 cents</span></p></div>
+
+<h2>LATHE WORK</h2>
+
+<p><b>Lathe Design, Construction, and Operation, with Practical Examples of
+Lathe Work.</b> By <span class="smcap">Oscar E. Perrigo</span>.</p>
+
+<div class="blockquot"><p>A new, revised edition, and the only complete American work on the subject, written by a
+man who knows not only how work ought to be done, but who also knows how to do it, and
+how to convey this knowledge to others. It is strictly up-to-date in its descriptions and
+illustrations. Lathe history and the relations of the lathe to manufacturing are given;
+also a description of the various devices for feeds and thread-cutting mechanisms from early
+efforts in this direction to the present time. Lathe design is thoroughly discussed, including
+back gearing, driving cones, thread-cutting gears, and all the essential elements of the
+modern lathe. The classification of lathes is taken up, giving the essential differences of
+the several types of lathes including, as is usually understood, engine lathes, bench lathes,
+speed lathes, forge lathes, gap lathes, pulley lathes, forming lathes, multiple-spindle lathes,
+rapid-reduction lathes, precision lathes, turret lathes, special lathes, electrically driven
+lathes,<span class='pagenum' style="font-size: 100%;"><a name="Page_Cat21" id="Page_Cat21">[21]</a></span>
+etc. In addition to the complete exposition on construction and design, much practical
+matter on lathe installation, care and operation has been incorporated in the enlarged new
+edition. All kinds of lathe attachments for drilling, milling, etc., are described and complete
+instructions are given to enable the novice machinist to grasp the art of lathe operation
+as well as the principles involved in design. A number of difficult machining operations
+are described at length and illustrated. The new edition has nearly 500 pages and 350 illustrations.
+Price <span class="price">$2.50</span></p>
+
+<h3>WHAT IS SAID OF THIS BOOK:</h3>
+
+<p>&#8220;This is a lathe book from beginning to end, and is just the kind of a book which one delights
+to consult&mdash;a masterly treatment of the subject in hand.&#8221;&mdash;<i>Engineering News.</i></p>
+
+<p>&#8220;This work will be of exceptional interest to any one who is interested in lathe practice, as
+one very seldom sees such a complete treatise on a subject as this is on the lathe.&#8221;&mdash;<i>Canadian
+Machinery.</i></p></div>
+
+<p><b>Practical Metal Turning.</b> By <span class="smcap">Joseph G. Horner</span>.</p>
+
+<div class="blockquot"><p>A work of 404 pages, fully illustrated, covering in a comprehensive manner the modern practice
+of machining metal parts in the lathe, including the regular engine lathe, its essential
+design, its uses, its tools, its attachments, and the manner of holding the work and performing
+the operations. The modernized engine lathe, its methods, tools and great range of accurate
+work. The turret lathe, its tools, accessories and methods of performing its functions.
+Chapters on special work, grinding, tool holders, speeds, feeds, modern tool steels, etc.
+Second edition <span class="price">$3.50</span></p></div>
+
+<p><b>Turning and Boring Tapers.</b> By <span class="smcap">Fred H. Colvin</span>.</p>
+
+<div class="blockquot"><p>There are two ways to turn tapers; the right way and one other. This treatise has to do
+with the right way; it tells you how to start the work properly, how to set the lathe, what
+tools to use and how to use them, and forty and one other little things that you should know.
+Fourth edition <span class="price">25 cents</span></p></div>
+
+<h2>LIQUID AIR</h2>
+
+<p><b>Liquid Air and the Liquefaction of Gases.</b> By <span class="smcap">T. O&#8217;Conor Sloane</span>.</p>
+
+<div class="blockquot"><p>This book gives the history of the theory, discovery and manufacture of Liquid Air, and
+contains an illustrated description of all the experiments that have excited the wonder of
+audiences all over the country. It shows how liquid air, like water, is carried hundreds of
+miles and is handled in open buckets. It tells what may be expected from it in the near
+future.</p>
+
+<p>A book that renders simple one of the most perplexing chemical problems of the century.
+Startling developments illustrated by actual experiments.</p>
+
+<p>It is not only a work of scientific interest and authority, but is intended for the general reader,
+being written in a popular style&mdash;easily understood by every one. Second edition. 365
+pages. Price <span class="price">$2.00</span></p></div>
+
+<h2>LOCOMOTIVE ENGINEERING</h2>
+
+<p><b>Air-Brake Catechism.</b> By <span class="smcap">Robert H. Blackall</span>.</p>
+
+<div class="blockquot"><p>This book is a standard text-book. It covers the Westinghouse Air-Brake Equipment,
+including the No. 5 and the No. 6 E.-T. Locomotive Brake Equipment; the K (Quick Service)
+Triple Valve for Freight Service; and the Cross-Compound Pump. The operation of
+all parts of the apparatus is explained in detail, and a practical way of finding their peculiarities
+and defects, with a proper remedy, is given. It contains 2,000 questions with their
+answers, which will enable any railroad man to pass any examination on the subject of
+Air Brakes. Endorsed and used by air-brake instructors and examiners on nearly every
+railroad in the United States. Twenty-sixth edition. 411 pages, fully illustrated with
+colored plates and diagrams. Price <span class="price">$2.00</span></p></div>
+
+<p><b>American Compound Locomotives.</b> By <span class="smcap">Fred H. Colvin</span>.</p>
+
+<div class="blockquot"><p>The only book on compounds for the engineman or shopman that shows in a plain, practical
+way the various features of compound locomotives in use. Shows how they are made,
+what to do when they break down or balk. Contains sections as follows: A Bit of History.
+Theory of Compounding Steam Cylinders. Baldwin Two-Cylinder Compound. Pittsburg
+Two-Cylinder Compound. Rhode Island Compound. Richmond Compound. Rogers Compound.
+Schenectady Two-Cylinder Compound. Vauclain Compound. Tandem Compounds.
+Baldwin Tandem. The Colvin-Wightman Tandem. Schenectady Tandem. Balanced
+Locomotives. Baldwin Balanced Compound. Plans for Balancing. Locating Blows.
+Breakdowns. Reducing Valves. Drifting. Valve Motion. Disconnecting. Power of Compound
+Locomotives. Practical Notes.</p>
+
+<p>Fully illustrated and containing ten special &#8220;Duotone&#8221; inserts on heavy Plate Paper, showing
+different types of Compounds. 142 pages. Price <span class="price">$1.00</span></p></div>
+
+<p><span class='pagenum'><a name="Page_Cat22" id="Page_Cat22">[22]</a></span><b>Application
+of Highly Superheated Steam to Locomotives.</b> By <span class="smcap">Robert
+Garbe</span>.</p>
+
+<div class="blockquot"><p>A practical book which cannot be recommended too highly to those motive-power men who
+are anxious to maintain the highest efficiency in their locomotives. Contains special chapters
+on Generation of Highly Superheated Steam; Superheated Steam and the Two-Cylinder
+Simple Engine; Compounding and Superheating; Designs of Locomotive Superheaters;
+Constructive Details of Locomotives Using Highly Superheated Steam. Experimental and
+Working Results. Illustrated with folding plates and tables. Cloth. Price <span class="price">$2.50</span></p></div>
+
+<p><b>Combustion of Coal and the Prevention of Smoke.</b> By <span class="smcap">Wm. M. Barr</span>.</p>
+
+<div class="blockquot"><p>This book has been prepared with special reference to the generation of heat by the combustion
+of the common fuels found in the United States and deals particularly with the
+conditions necessary to the economic and smokeless combustion of bituminous coal in Stationary
+and Locomotive Steam Boilers.</p>
+
+<p>Presentation of this important subject is systematic and progressive. The arrangement of
+the book is in a series of practical questions to which are appended accurate answers, which
+describe in language free from technicalities the several processes involved in the furnace
+combustion of American fuels; it clearly states the essential requisites for perfect combustion,
+and points out the best methods of furnace construction for obtaining the greatest
+quantity of heat from any given quality of coal. Nearly 350 pages, fully illustrated.
+Price <span class="price">$1.00</span></p></div>
+
+<p><b>Diary of a Round-House Foreman.</b> By <span class="smcap">T. S. Reilly</span>.</p>
+
+<div class="blockquot"><p>This is the greatest book of railroad experiences ever published. Containing a fund of information
+and suggestions along the line of handling men, organizing, etc., that one cannot
+afford to miss. 176 pages. Price <span class="price">$1.00</span></p></div>
+
+<p><b>Link Motions, Valves and Valve Setting.</b> By <span class="smcap">Fred H. Colvin</span>, Associate Editor
+of &#8220;American Machinist.&#8221;</p>
+
+<div class="blockquot"><p>A handy book for the engineer or machinist that clears up the mysteries of valve setting.
+Shows the different valve gears in use, how they work, and why. Piston and slide valves
+of different types are illustrated and explained. A book that every railroad man in the
+motive-power department ought to have. Contains chapters on Locomotive Link Motion,
+Valve Movements, Setting Slide Valves, Analysis by Diagrams, Modern Practice, Slip of
+Block, Slice Valves, Piston Valves, Setting Piston Valves, Joy-Allen Valve Gear, Walschaert
+Valve Gear, Gooch Valve Gear, Alfree-Hubbell Valve Gear, etc., etc. Fully illustrated.
+Price <span class="price">50 cents</span></p></div>
+
+<p><b>Locomotive Boiler Construction.</b> By <span class="smcap">Frank A. Kleinhans</span>.</p>
+
+<div class="blockquot"><p>The construction of boilers in general is treated and, following this, the locomotive boiler
+is taken up in the order in which its various parts go through the shop. Shows all types
+of boilers used; gives details of construction; practical facts, such as life of riveting, punches
+and dies; work done per day, allowance for bending and flanging sheets and other data.
+Including the recent Locomotive Boiler Inspection Laws and Examination Questions with
+their answers for Government Inspectors. Contains chapters on Laying-Out Work; Flanging
+and Forging; Punching; Shearing; Plate Planing; General Tables; Finishing Parts;
+Bending; Machinery Parts; Riveting; Boiler Details; Smoke-Box Details; Assembling
+and Calking; Boiler-Shop Machinery, etc., etc.</p>
+
+<p>There isn&#8217;t a man who has anything to do with boiler work, either new or repair work, who
+doesn&#8217;t need this book. The manufacturer, superintendent, foreman and boiler worker&mdash;all
+need it. No matter what the type of boiler, you&#8217;ll find a mint of information that you
+wouldn&#8217;t be without. Over 400 pages, five large folding plates. Price <span class="price">$3.00</span></p></div>
+
+<p><b>Locomotive Breakdowns and their Remedies.</b> By <span class="smcap">Geo. L. Fowler</span>. Revised
+by <span class="smcap">Wm. W. Wood</span>, Air-Brake Instructor. Just issued. Revised pocket
+edition.</p>
+
+<div class="blockquot"><p>It is out of the question to try and tell you about every subject that is covered in this pocket
+edition of Locomotive Breakdowns. Just imagine all the common troubles that an engineer
+may expect to happen some time, and then add all of the unexpected ones, troubles that could
+occur, but that you have never thought about, and you will find that they are all treated with
+the very best methods of repair. Walschaert Locomotive Valve Gear Troubles, Electric
+Headlight Troubles, as well as Questions and Answers on the Air Brake are all included. 312
+pages. 8th Revised Edition. Fully illustrated. Price <span class="price">$1.00</span></p></div>
+
+<p><b>Locomotive Catechism.</b> By <span class="smcap">Robert Grimshaw</span>.</p>
+
+<div class="blockquot"><p>The revised edition of &#8220;Locomotive Catechism,&#8221; by Robert Grimshaw, is a New Book from
+Cover to Cover. It contains twice as many pages and double the number of illustrations of
+previous editions. Includes the greatest amount of practical information ever published on
+the construction and management of modern locomotives. Specially Prepared Chapters on
+the Walschaert Locomotive Valve Gear, the Air-Brake Equipment and the Electric Headlight
+are given.</p>
+
+<p><span class='pagenum' style="font-size: 100%;"><a name="Page_Cat23" id="Page_Cat23">[23]</a></span>It
+commends itself at once to every Engineer and Fireman, and to all who are going in for
+examination or promotion. In plain language, with full, complete answers, not only all the
+questions asked by the examining engineer are given, but those which the young and less
+experienced would ask the veteran, and which old hands ask as &#8220;stickers.&#8221; It is a veritable
+Encyclopedia of the Locomotive, is entirely free from mathematics, easily understood and
+thoroughly up to date. Contains over 4,000 Examination Questions with their Answers.
+825 pages, 437 illustrations, and 3 folding plates. 28th Revised Edition. Price <span class="price">$2.50</span></p></div>
+
+<p><b>Practical Instructor and Reference Book for Locomotive Firemen and
+Engineers.</b> By <span class="smcap">Chas. F. Lockhart</span>.</p>
+
+<div class="blockquot"><p>An entirely new book on the Locomotive. It appeals to every railroad man, as it tells him
+how things are done and the right way to do them. Written by a man who has had years of
+practical experience in locomotive shops and on the road firing and running. The information
+given in this book cannot be found in any other similar treatise. Eight hundred and fifty-one
+questions with their answers are included, which will prove specially helpful to those preparing
+for examination. Practical information on: The Construction and Operation of Locomotives,
+Breakdowns and their Remedies, Air Brakes and Valve Gears. Rules and Signals are handled
+in a thorough manner. As a book of reference it cannot be excelled. The book is divided
+into six parts, as follows: 1. The Fireman&#8217;s Duties. 2. General Description of the Locomotive.
+3. Breakdowns and their Remedies. 4. Air Brakes. 5. Extracts from Standard Rules.
+6. Questions for Examination. The 851 questions have been carefully selected and arranged.
+These cover the examinations required by the different railroads. 368 pages, 88 illustrations.
+Price <span class="price">$1.50</span></p></div>
+
+<p><b>Prevention of Railroad Accidents, or Safety in Railroading.</b> By <span class="smcap">George
+Bradshaw</span>.</p>
+
+<div class="blockquot"><p>This book is a heart-to-heart talk with Railroad Employees, dealing with facts, not theories,
+and showing the men in the ranks, from every-day experience, how accidents occur and how
+they may be avoided. The book is illustrated with seventy original photographs and drawings
+showing the safe and unsafe methods of work. No visionary schemes, no ideal pictures.
+Just Plain Facts and Practical Suggestions are given. Every railroad employee who reads the
+book is a better and safer man to have in railroad service. It gives just the information which
+will be the means of preventing many injuries and deaths. All railroad employees should
+procure a copy, read it, and do their part in preventing accidents. 169 pages. Pocket size.
+Fully illustrated. Price <span class="price">50 cents</span></p></div>
+
+<p><b>Train Rule Examinations Made Easy.</b> By <span class="smcap">G. E. Collingwood</span>.</p>
+
+<div class="blockquot"><p>This is the only practical work on train rules in print. Every detail is covered, and puzzling
+points are explained in simple, comprehensive language, making it a practical treatise for the
+Train Dispatcher, Engineman, Trainman, and all others who have to do with the movements
+of trains. Contains complete and reliable information of the Standard Code of Train Rules
+for single track. Shows Signals in Colors, as used on the different roads. Explains fully the
+practical application of train orders, giving a clear and definite understanding of all orders
+which may be used. The meaning and necessity for certain rules are explained in such a
+manner that the student may know beyond a doubt the rights conferred under any orders he
+may receive or the action required by certain rules. As nearly all roads require trainmen to
+pass regular examinations, a complete set of examination questions, with their answers, are
+included. These will enable the student to pass the required examinations with credit to
+himself and the road for which he works. 2nd Edition, Revised. 256 pages, fully illustrated,
+with Train Signals in Colors. Price <span class="price">$1.25</span></p></div>
+
+<p><b>The Walschaert and Other Modern Radial Valve Gears for Locomotives.</b>
+By <span class="smcap">Wm. W. Wood</span>.</p>
+
+<div class="blockquot"><p>If you would thoroughly understand the Walschaert Valve Gear you should possess a copy
+of this book, as the author takes the plainest form of a steam engine&mdash;a stationary engine in
+the rough, that will only turn its crank in one direction&mdash;and from it builds up, with the reader&#8217;s
+help, a modern locomotive equipped with the Walschaert Valve Gear, complete. The
+points discussed are clearly illustrated: Two large folding plates that show the positions of
+the valves of both inside or outside admission type, as well as the links and other parts of the
+gear when the crank is at nine different points in its revolution, are especially valuable in making
+the movement clear. These employ sliding cardboard models which are contained in a
+pocket in the cover.</p>
+
+<p>The book is divided into five general divisions, as follows: 1. Analysis of the gear. 2. Designing
+and erecting the gear. 3. Advantages of the gear. 4. Questions and answers relating
+to the Walschaert Valve Gear. 5. Setting valves with the Walschaert Valve Gear; the three
+primary types of locomotive valve motion; modern radial valve gears other than the Walschaert;
+the Hobart All-free Valve and Valve Gear, with questions and answers on breakdowns;
+the Baker-Pilliod Valve Gear; the Improved Baker-Pilliod Valve Gear, with questions and
+answers on breakdowns.</p>
+
+<p>The questions with full answers given will be especially valuable to firemen and engineers in
+preparing for an examination for promotion. 245 pages. 3rd Revised Edition. Price <span class="price">$1.50</span></p></div>
+
+<p><span class='pagenum'><a name="Page_Cat24" id="Page_Cat24">[24]</a></span><b>Westinghouse
+E-T Air-Brake Instruction Pocket Book.</b> By <span class="smcap">Wm. W. Wood</span>,
+Air-Brake Instructor.</p>
+
+<div class="blockquot"><p>Here is a book for the railroad man, and the man who aims to be one. It is without doubt
+the only complete work published on the Westinghouse E-T Locomotive Brake Equipment.
+Written by an Air-Brake Instructor who knows just what is needed. It covers the subject
+thoroughly. Everything about the New Westinghouse Engine and Tender Brake Equipment,
+including the standard No. 5 and the Perfected No. 6 style of brake, is treated in detail.
+Written in plain English and profusely illustrated with Colored Plates, which enable one to
+trace the flow of pressures throughout the entire equipment. The best book ever published
+on the Air Brake. Equally good for the beginner and the advanced engineer. Will pass any
+one through any examination. It informs and enlightens you on every point. Indispensable
+to every engineman and trainman.</p>
+
+<p>Contains examination questions and answers on the E-T equipment. Covering what the E-T
+Brake is. How it should be operated. What to do when defective. Not a question can be
+asked of the engineman up for promotion, on either the No. 5 or the No. 6 E-T equipment,
+that is not asked and answered in the book. If you want to thoroughly understand the E-T
+equipment get a copy of this book. It covers every detail. Makes Air-Brake troubles and
+examinations easy. Price <span class="price">$1.50</span></p></div>
+
+<h2>MACHINE-SHOP PRACTICE</h2>
+
+<p><b>American Tool Making and Interchangeable Manufacturing.</b> By <span class="smcap">J. V.
+Woodworth</span>.</p>
+
+<div class="blockquot"><p>A &#8220;shoppy&#8221; book, containing no theorizing, no problematical or experimental devices. There
+are no badly proportioned and impossible diagrams, no catalogue cuts, but a valuable collection
+of drawings and descriptions of devices, the rich fruits of the author&#8217;s own experience.
+In its 500-odd pages the one subject only, Tool Making, and whatever relates thereto, is dealt
+with. The work stands without a rival. It is a complete, practical treatise, on the art of
+American Tool Making and system of interchangeable manufacturing as carried on to-day in
+the United States. In it are described and illustrated all of the different types and classes of
+small tools, fixtures, devices, and special appliances which are in general use in all machine-manufacturing
+and metal-working establishments where economy, capacity, and interchangeability
+in the production of machined metal parts are imperative. The science of jig making
+is exhaustively discussed, and particular attention is paid to drill jigs, boring, profiling and
+milling fixtures and other devices in which the parts to be machined are located and fastened
+within the contrivances. All of the tools, fixtures, and devices illustrated and described have
+been or are used for the actual production of work, such as parts of drill presses, lathes, patented
+machinery, typewriters, electrical apparatus, mechanical appliances, brass goods, composition
+parts, mould products, sheet-metal articles, drop-forgings, jewelry, watches, medals, coins, etc.
+531 pages. Price <span class="price">$4.00</span></p></div>
+
+<p><b>HENLEY&#8217;S ENCYCLOPEDIA OF PRACTICAL ENGINEERING AND ALLIED
+TRADES.</b> <span class="smcap">Edited</span> by <span class="smcap">Joseph G. Horner</span>, A.M.I., M.E.</p>
+
+<div class="blockquot"><p>This set of five volumes contains about 2,500 pages with thousands of illustrations, including
+diagrammatic and sectional drawings with full explanatory details. This work covers the
+entire practice of Civil and Mechanical Engineering. The best known experts in all branches
+of engineering have contributed to these volumes. The Cyclopedia is admirably well adapted
+to the needs of the beginner and the self-taught practical man, as well as the mechanical
+engineer, designer, draftsman, shop superintendent, foreman, and machinist. The work will
+be found a means of advancement to any progressive man. It is encyclopedic in scope, thorough
+and practical in its treatment on technical subjects, simple and clear in its descriptive
+matter, and without unnecessary technicalities or formul&aelig;. The articles are as brief as may
+be and yet give a reasonably clear and explicit statement of the subject, and are written by
+men who have had ample practical experience in the matters of which they write. It tells
+you all you want to know about engineering and tells it so simply, so clearly, so concisely, that
+one cannot help but understand. As a work of reference it is without a peer. Complete
+set of five volumes, price <span class="price">$25.00</span></p></div>
+
+<p><b>The Modern Machinist.</b> By <span class="smcap">John T. Usher</span>.</p>
+
+<div class="blockquot"><p>This is a book, showing by plain description and by profuse engravings made expressly for
+the work, all that is best, most advanced, and of the highest efficiency in modern machine-shop
+practice, tools and implements, showing the way by which and through which, as Mr.
+Maxim says &#8220;American machinists have become and are the finest mechanics in the world.&#8221;
+Indicating as it does, in every line, the familiarity of the author with every detail of daily
+experience in the shop, it cannot fail to be of service to any man practically connected with
+the shaping or finishing of metals.</p>
+
+<p>There is nothing experimental or visionary about the book, all devices being in actual use
+and giving good results. It might be called a compendium of shop methods, showing a
+variety of special tools and appliances which will give new ideas to many mechanics, from
+the superintendent down to the man at the bench. It will be found a valuable addition to
+any machinist&#8217;s library, and should be consulted whenever a new or difficult job is to be
+done, whether it is boring, milling, turning, or planing, as they are all treated m a practical
+manner. Fifth edition. 320 pages. 250 illustrations. Price <span class="price">$2.50</span></p></div>
+
+<p class='pagenum'><a name="Page_Cat25" id="Page_Cat25">[25]</a></p>
+
+<h3>THE WHOLE FIELD OF MECHANICAL MOVEMENTS
+COVERED BY MR. HISCOX&#8217;S TWO BOOKS</h3>
+
+<div class="blockquot"><p><i>We publish two books by Gardner D. Hiscox that will keep you from &#8220;inventing&#8221; things that have
+been done before, and suggest ways of doing things that you have not thought of before. Many a
+man spends time and money pondering over some mechanical problem, only to learn, after he
+has solved the problem, that the same thing has been accomplished and put in practice by others
+long before. Time and money spent in an effort to accomplish what has already been accomplished
+are time and money LOST. The whole field of mechanics, every known mechanical movement,
+and practically every device are covered by these two books. If the thing you want has been invented,
+it is illustrated in them. If it hasn&#8217;t been invented, then you&#8217;ll find in them the nearest things
+to what you want, some movements or devices that will apply in your case, perhaps; or which
+will give you a key from which to work. No book or set of books ever published is of more real
+value to the Inventor, Draftsman, or practical Mechanic than the two volumes described below.</i></p></div>
+
+<p><b>Mechanical Movements, Powers, and Devices.</b> By <span class="smcap">Gardner D. Hiscox</span>.</p>
+
+<div class="blockquot"><p>This is a collection of 1,890 engravings of different mechanical motions and appliances, accompanied
+by appropriate text, making it a book of great value to the inventor, the draftsman,
+and to all readers with mechanical tastes. The book is divided into eighteen sections
+or chapters, in which the subject-matter is classified under the following heads: Mechanical
+Powers; Transmission of Power; Measurement of Power; Steam Power; Air Power Appliances;
+Electric Power and Construction; Navigation and Roads; Gearing; Motion and
+Devices; Controlling Motion; Horological; Mining; Mill and Factory Appliances; Construction
+and Devices; Drafting Devices; Miscellaneous Devices, etc. 15th Edition. 400
+octavo pages. Price <span class="price">$3.00</span></p></div>
+
+<p><b>Mechanical Appliances, Mechanical Movements and Novelties of Construction.</b>
+By <span class="smcap">Gardner D. Hiscox</span>.</p>
+
+<div class="blockquot"><p>This is a supplementary volume to the one upon mechanical movements. Unlike the first
+volume, which is more elementary in character, this volume contains illustrations and descriptions
+of many combinations of motions and of mechanical devices and appliances found
+in different lines of machinery, each device being shown by a line drawing with a description
+showing its working parts and the method of operation. From the multitude of devices described
+and illustrated might be mentioned, in passing, such items as conveyors and elevators,
+Pony brakes, thermometers, various types of boilers, solar engines, oil-fuel burners, condensers,
+evaporators, Corliss and other valve gears, governors, gas engines, water motors of various
+descriptions, air ships, motors and dynamos, automobile and motor bicycles, railway lock
+signals, car couplers, link and gear motions, ball bearings, breech-block mechanism for heavy
+guns, and a large accumulation of others of equal importance. One thousand specially made
+engravings. 396 octavo pages. Fourth edition. Price <span class="price">$3.00</span></p></div>
+
+<p><b>Machine-Shop Tools and Shop Practice.</b> By <span class="smcap">W. H. Vandervoort</span>.</p>
+
+<div class="blockquot"><p>A work of 555 pages and 673 illustrations, describing in every detail the construction, operation
+and manipulation of both hand and machine tools. Includes chapters on filing, fitting
+and scraping surfaces; on drills, reamers, taps and dies; the lathe and its tools: planers,
+shapers, and their tools; milling machines and cutters; gear cutters and gear cutting; drilling
+machines and drill work; grinding machines and their work; hardening and tempering;
+gearing, belting and transmission machinery; useful data and tables. Sixth edition.
+Price <span class="price">$3.00</span></p></div>
+
+<p><b>Machine-Shop Arithmetic.</b> By <span class="smcap">Colvin-Cheney</span>.</p>
+
+<div class="blockquot"><p>This is an arithmetic of the things you have to do with daily. It tells you plainly about:
+how to find areas in figures; how to find surface or volume of balls or spheres; handy ways
+for calculating; about compound gearing; cutting screw threads on any lathe; drilling for
+taps; speeds of drills; taps, emery wheels, grindstones, milling cutters, etc.; all about the
+Metric system with conversion tables; properties of metals; strength of bolts and nuts;
+decimal equivalent of an inch. All sorts of machine-shop figuring and 1,001 other things,
+any one of which ought to be worth more than the price of this book to you, as it saves you
+the trouble of bothering the boss. 6th Edition. 131 pages. Price <span class="price">50 cents</span></p></div>
+
+<p><b>Modern Machine-Shop Construction, Equipment and Management.</b> By
+<span class="smcap">Oscar E. Perrigo</span>.</p>
+
+<div class="blockquot"><p>The only work published that describes the Modern Shop or Manufacturing Plant from the
+time the grass is growing on the site intended for it until the finished product is shipped. Just
+the book needed by those contemplating the erection of modern shop buildings, the rebuilding
+and reorganization of old ones, or the introduction of Modern Shop Methods, time and cost
+systems. It is a book written and illustrated by a practical shop man for practical shop men
+who are too busy to read theories and want facts. It is the most complete all-round book of
+its kind ever published. Second Edition, Revised. 384 large quarto pages. 219 original and
+specially made illustrations. 2nd Revised and Enlarged Edition. Price <span class="price">$5.00</span></p></div>
+
+<p><span class='pagenum'><a name="Page_Cat26" id="Page_Cat26">[26]</a></span><b>Modern
+Milling Machines: Their Design, Construction, and Operation.</b>
+By <span class="smcap">Joseph G. Horner</span>.</p>
+
+<div class="blockquot"><p>This book describes and illustrates the Milling Machine and its work in such a plain, clear
+and forceful manner, and illustrates the subject so clearly and completely, that the up-to-date
+machinist, student or mechanical engineer cannot afford to do without the valuable
+information which it contains. It describes not only the early machines of this class, but notes
+their gradual development into the splendid machines of the present day, giving the design
+and construction of the various types, forms, and special features produced by prominent
+manufacturers, American and foreign. 304 pages, 300 illustrations. Cloth. Price <span class="price">$4.00</span></p></div>
+
+<p><b>&#8220;Shop Kinks.&#8221;</b> By <span class="smcap">Robert Grimshaw</span>.</p>
+
+<div class="blockquot"><p>A book of 400 pages and 222 illustrations, being entirely different from any other book on
+machine-shop practice. Departing from conventional style, the author avoids universal
+or common shop usage and limits his work to showing special ways of doing things better,
+more cheaply and more rapidly than usual. As a result the advanced methods of representative
+establishments of the world are placed at the disposal of the reader. This book shows
+the proprietor where large savings are possible, and how products may be improved. To
+the employee it holds out suggestions that, properly applied, will hasten his advancement.
+No shop can afford to be without it. It bristles with valuable wrinkles and helpful suggestions.
+It will benefit all, from apprentice to proprietor. Every machinist, at any age, should
+study its pages. Fifth edition. Price <span class="price">$2.50</span></p></div>
+
+<p><b>Threads and Thread Cutting.</b> By <span class="smcap">Colvin</span> and <span class="smcap">Stabel</span>.</p>
+
+<div class="blockquot"><p>This clears up many of the mysteries of thread-cutting, such as double and triple threads,
+internal threads, catching threads, use of hobs, etc. Contains a lot of useful hints and several
+tables. Third edition. Price <span class="price">25 cents</span></p></div>
+
+<h2>MANUAL TRAINING</h2>
+
+<p><b>Economics of Manual Training.</b> By <span class="smcap">Louis Rouillion</span>.</p>
+
+<div class="blockquot"><p>The only book published that gives just the information needed by all interested in Manual
+Training, regarding Buildings, Equipment, and Supplies. Shows exactly what is needed
+for all grades of the work from the Kindergarten to the High and Normal School. Gives
+itemized lists of everything used in Manual Training Work and tells just what it ought to
+cost. Also shows where to buy supplies, etc. Contains 174 pages, and is fully illustrated.
+Second edition. Price <span class="price">$1.50</span></p></div>
+
+<h2>MARINE ENGINEERING</h2>
+
+<p><b>The Naval Architect&#8217;s and Shipbuilder&#8217;s Pocket Book of Formul&aelig;, Rules,
+and Tables and Marine Engineer&#8217;s and Surveyor&#8217;s Handy Book of
+Reference.</b> By <span class="smcap">Clement Mackrow</span> and <span class="smcap">Lloyd Woollard</span>.</p>
+
+<div class="blockquot"><p>The eleventh Revised and Enlarged Edition of this most comprehensive work has just been
+issued. It is absolutely indispensable to all engaged in the Shipbuilding Industry, as it condenses
+into a compact form all data and formul&aelig; that are ordinarily required. The book is
+completely up to date, including among other subjects a section on Aeronautics. 750 pages,
+limp leather binding. Price <b>$5.00 net</b></p></div>
+
+<p><b>Marine Engines and Boilers: Their Design and Construction.</b> By <span class="smcap">Dr. G.
+Bauer</span>, <span class="smcap">Leslie S. Robertson</span> and <span class="smcap">S. Bryan Donkin</span>.</p>
+
+<div class="blockquot"><p>In the words of Dr. Bauer, the present work owes its origin to an oft felt want of a condensed
+treatise embodying the theoretical and practical rules used in designing marine engines and
+boilers. The need of such a work has been felt by most engineers engaged in the construction
+and working of marine engines, not only by the younger men, but also by those of greater experience.
+The fact that the original German work was written by the chief engineer of the
+famous Vulcan Works, Stettin, is in itself a guarantee that this book is in all respects thoroughly
+up-to-date, and that it embodies all the information which is necessary for the design
+and construction of the highest types of marine engines and boilers. It may be said that the
+motive power which Dr. Bauer has placed in the fast German liners that have been turned out
+of late years from the Stettin Works represent the very best practice in marine engineering of
+the present day. The work is clearly written, thoroughly systematic, theoretically sound;
+while the character of the plans, drawings, tables, and statistics is without reproach. The
+illustrations are careful reproductions from actual working drawings, with some well-executed
+photographic views of completed engines and boilers. 744 pages, 550 illustrations and numerous
+tables. Cloth. Price <b>$9.00 net</b></p></div>
+
+<p class='pagenum'><a name="Page_Cat27" id="Page_Cat27">[27]</a></p>
+
+<h2>MINING</h2>
+
+<p><b>Ore Deposits, with a Chapter on Hints to Prospectors.</b> By <span class="smcap">J. P. Johnson</span>.</p>
+
+<div class="blockquot"><p>This book gives a condensed account of the ore deposits at present known in South Africa.
+It is also intended as a guide to the prospector. Only an elementary knowledge of geology
+and some mining experience are necessary in order to understand this work. With these
+qualifications, it will materially assist one in his search for metalliferous mineral occurrences
+and, so far as simple ores are concerned, should enable one to form some idea of the possibilities
+of any he may find. Illustrated. Cloth. Price <span class="price">$2.00</span></p></div>
+
+<p><b>Practical Coal Mining.</b> By <span class="smcap">T. H. Cockin</span>.</p>
+
+<div class="blockquot"><p>An important work, containing 428 pages and 213 illustrations, complete with practical details,
+which will intuitively impart to the reader not only a general knowledge of the principles
+of coal mining, but also considerable insight into allied subjects. The treatise is positively
+up-to-date in every instance, and should be in the hands of every colliery engineer, geologist,
+mine operator, superintendent, foreman, and all others who are interested in or connected with
+the industry. 3d Edition. Cloth. Price <span class="price">$2.50</span></p></div>
+
+<p><b>Physics and Chemistry of Mining.</b> By <span class="smcap">T. H. Byrom</span>.</p>
+
+<div class="blockquot"><p>A practical work for the use of all preparing for examinations in mining or qualifying for
+colliery managers&#8217; certificates. The aim of the author in this excellent book is to place clearly
+before the reader useful and authoritative data which will render him valuable assistance in
+his studies. The only work of its kind published. The information incorporated in it will
+prove of the greatest practical utility to students, mining engineers, colliery managers, and
+all others who are specially interested in the present-day treatment of mining problems. 160
+pages, illustrated. Price <span class="price">$2.00</span></p></div>
+
+<h2>PATTERN MAKING</h2>
+
+<p><b>Practical Pattern Making.</b> By <span class="smcap">F. W. Barrows</span>.</p>
+
+<div class="blockquot"><p>This book, now in its second edition, is a comprehensive and entirely practical treatise on the
+subject of pattern making, illustrating pattern work in both wood and metal, and with definite
+instructions on the use of plaster of paris in the trade. It gives specific and detailed descriptions
+of the materials used by pattern makers, and describes the tools, both those for the
+bench and the more interesting machine tools, having complete chapters on the Lathe, the
+Circular Saw, and the Band Saw. It gives many examples of pattern work, each one fully
+illustrated and explained with much detail. These examples, in their great variety, offer much
+that will be found of interest to all pattern makers, and especially to the younger ones, who
+are seeking information on the more advanced branches of their trade.</p>
+
+<p>In this second edition of the work will be found much that is new, even to those who have
+long practised this exacting trade. In the description of patterns as adapted to the Moulding
+Machine many difficulties which have long prevented the rapid and economical production of
+castings are overcome; and this great, new branch of the trade is given much space. Stripping
+plate and stool plate work and the less expensive vibrator, or rapping plate work, are
+all explained in detail.</p>
+
+<p>Plain, every-day rules for lessening the cost of patterns, with a complete system of cost
+keeping, a detailed method of marking, applicable to all branches of the trade, with complete
+information showing what the pattern is, its specific title, its cost, date of production,
+material of which it is made, the number of pieces and core-boxes, and its location in the
+pattern safe, all condensed into a most complete card record, with cross index.
+The book closes with an original and practical method for the inventory and valuation of
+patterns. Containing nearly 350 pages and 170 illustrations. Price <span class="price">$2.00</span></p></div>
+
+<h2>PERFUMERY</h2>
+
+<p><b>Perfumes and Cosmetics: Their Preparation and Manufacture.</b> By <span class="smcap">G. W.
+Askinson</span>, Perfumer.</p>
+
+<div class="blockquot"><p>A comprehensive treatise, in which there has been nothing omitted that could be of value
+to the perfumer or manufacturer of toilet preparations. Complete directions for making
+handkerchief perfumes, smelling-salts, sachets, fumigating pastilles; preparations for the
+care of the skin, the mouth, the hair, cosmetics, hair dyes and other toilet articles are given,
+also a detailed description of aromatic substances; their nature, tests of purity, and wholesome
+manufacture, including a chapter on synthetic products, with formulas for their use.
+A book of general as well as professional interest, meeting the wants not only of the druggist
+and perfume manufacturer, but also of the general public. Among the contents are:
+1. The History of Perfumery. 2. About Aromatic Substances in General. 3. Odors from
+the Vegetable Kingdom. 4. The Aromatic Vegetable Substances Employed in Perfumery.
+5. The Animal Substances Used in Perfumery. 6. The Chemical Products Used in Perfumery.
+7. The Extraction of Odors. 8. The Special Characteristics of Aromatic Substances. 9 The
+Adulteration of Essential Oils and Their Recognition. 10. Synthetic Products. 11. Table
+of Physical Properties of Aromatic Chemicals. 12. The Essences or Extracts Employed
+in Perfumery. 13. Directions for Making the Most Important Essences and Extracts.<span
+class='pagenum' style="font-size: 100%;"><a name="Page_Cat28" id="Page_Cat28">[28]</a></span>
+14. The Division of Perfumery. 15. The Manufacture of Handkerchief Perfumes. 16. Formulas
+for Handkerchief Perfumes. 17. Ammoniacal and Acid Perfumes. 18. Dry Perfumes.
+19. Formulas for Dry Perfumes. 20. The Perfumes Used for Fumigation. 21. Antiseptic
+and Therapeutic Value of Perfumes. 22. Classification of Odors. 23. Some Special
+Perfumery Products. 24. Hygiene and Cosmetic Perfumery. 25. Preparations for the Care
+of the Skin. 26. Manufacture of Casein. 27. Formulas for Emulsions. 28. Formulas for
+Cream. 29. Formulas for Meals, Pastes and Vegetable Milk. 30. Preparations Used for
+the Hair. 31. Formulas for Hair Tonics and Restorers. 32. Pomades and Hair Oils
+33. Formulas for the Manufacture of Pomades and Hair Oils. 34. Hair Dyes and Depilatories.
+35. Wax Pomades, Bandolines and Brilliantines. 36. Skin Cosmetics and
+Face Lotions. 37. Preparations for the Nails. 38. Water Softeners and Bath Salts. 39.
+Preparations for the Care of the Mouth. 40. The Colors Used in Perfumery. 41. The Utensils
+Used in the Toilet. Fourth edition, much enlarged and brought up to date. Nearly
+400 pages, illustrated. Price <span class="price">$5.00</span></p>
+
+<h3>WHAT IS SAID OF THIS BOOK:</h3>
+
+<p>&#8220;The most satisfactory work on the subject of Perfumery that we have ever seen.&#8221;</p>
+
+<p>&#8220;We feel safe in saying that here is a book on Perfumery that will not disappoint you, for
+it has practical and excellent formul&aelig; that are within your ability to prepare readily.&#8221;</p>
+
+<p>&#8220;We recommend the volume as worthy of confidence, and say that no purchaser will be disappointed
+in securing from its pages good value for its cost, and a large dividend on the same,
+even if he should use but one per cent. of its working formul&aelig;. There is money in it for every
+user of its information.&#8221;&mdash;<i>Pharmaceutical Record.</i></p></div>
+
+<h2>PLUMBING</h2>
+
+<p><b>Mechanical Drawing for Plumbers.</b> By <span class="smcap">R. M. Starbuck</span>.</p>
+
+<div class="blockquot"><p>A concise, comprehensive and practical treatise on the subject of mechanical drawing in its
+various modern applications to the work of all who are in any way connected with the plumbing
+trade. Nothing will so help the plumber in estimating and in explaining work to customers
+and workmen as a knowledge of drawing, and to the workman it is of inestimable
+value if he is to rise above his position to positions of greater responsibility. Among the
+chapters contained are: 1. Value to plumber of knowledge of drawing; tools required and
+their use; common views needed in mechanical drawing. 2. Perspective versus mechanical
+drawing in showing plumbing construction. 3. Correct and incorrect methods in plumbing
+drawing; plan and elevation explained. 4. Floor and cellar plans and elevation; scale
+drawings; use of triangles. 5. Use of triangles; drawing of fittings, traps, etc. 6. Drawing
+plumbing elevations and fittings. 7. Instructions in drawing plumbing elevations. 8. The
+drawing of plumbing fixtures; scale drawings. 9. Drawings of fixtures and fittings. 10. Inking
+of drawings. 11. Shading of drawings. 12. Shading of drawings. 13. Sectional drawings;
+drawing of threads. 14. Plumbing elevations from architect&#8217;s plan. 15. Elevations of separate
+parts of the plumbing system. 16. Elevations from the architect&#8217;s plans. 17. Drawings
+of detail plumbing connections. 18. Architect&#8217;s plans and plumbing elevations of residence.
+19. Plumbing elevations of residence (<i>continued</i>); plumbing plans for cottage. 20. Plumbing
+elevations; roof connections. 21. Plans and plumbing elevations for six-flat building. 22.
+Drawing of various parts of the plumbing system; use of scales. 23. Use of architect&#8217;s scales.
+24. Special features in the illustrations of country plumbing. 25. Drawing of wrought-iron
+piping, valves, radiators, coils, etc. 26. Drawing of piping to illustrate heating systems.
+150 illustrations. Price <span class="price">$1.50</span></p></div>
+
+<p><b>Modern Plumbing Illustrated.</b> By <span class="smcap">R. M. Starbuck</span>.</p>
+
+<div class="blockquot"><p>This book represents the highest standard of plumbing work. It has been adopted and used
+as a reference book by the United States Government in its sanitary work in Cuba, Porto
+Rico and the Philippines, and by the principal Boards of Health of the United States and
+Canada.</p>
+
+<p>It gives connections, sizes and working data for all fixtures and groups of fixtures. It is helpful
+to the master plumber in demonstrating to his customers and in figuring work. It gives
+the mechanic and student quick and easy access to the best modern plumbing practice. Suggestions
+for estimating plumbing construction are contained in its pages. This book represents,
+in a word, the latest and best up-to-date practice and should be in the hands of every
+architect, sanitary engineer and plumber who wishes to keep himself up to the minute on
+this important feature of construction. Contains following chapters, each illustrated with a
+full-page plate: Kitchen sink, laundry tubs, vegetable wash sink; lavatories, pantry sinks,
+contents of marble slabs; bath tub, foot and sitz bath, shower bath; water closets, venting
+of water closets; low-down water closets, water closets operated by flush valves, water closet
+range; slop sink, urinals, the bidet; hotel and restaurant sink, grease trap; refrigerators,
+safe wastes, laundry waste, lines of refrigerators, bar sinks, soda fountain sinks; horse stall,
+frost-proof water closets; connections for S traps, venting; connections for drum traps;
+soil-pipe connections; supporting of soil pipe; main trap and fresh-air inlet: floor drains and
+cellar drains, subsoil drainage; water closets and floor connections; local venting; connections
+for bath rooms; connections for bath rooms, <i>continued</i>; examples of poor practice; roughing
+work ready for test; testing of plumbing systems; method of continuous venting; continuous
+venting for two-floor work; continuous venting for two lines of fixtures on three or more
+floors; continuous venting of water closets; plumbing for cottage house; construction for
+cellar piping; plumbing for residence, use of special fittings; plumbing for two-flat house:
+plumbing for apartment building, plumbing for double apartment building; plumbing for
+office building; plumbing for public toilet rooms; plumbing for public toilet rooms, <i>continued</i>;
+plumbing for bath establishment; plumbing for engine house, factory plumbing,
+automatic flushing for schools, factories, etc.; use of flushing valves; urinals for public toilet
+rooms; the Durham system, the destruction of pipes by electrolysis; construction of
+work<span class='pagenum' style="font-size: 100%;"><a name="Page_Cat29" id="Page_Cat29">[29]</a></span>
+without use of lead; automatic sewage lift; automatic sump tank; country plumbing;
+construction of cesspools; septic tank and automatic sewage siphon; water supply for
+country house; thawing of water mains and service by electricity; double boilers; hot
+water supply of large buildings; automatic control of hot-water tank; suggestions for
+estimating plumbing construction. 407 octavo pages, fully illustrated by 57 full-page
+engravings. Third, revised and enlarged edition, just issued. Price <span class="price">$4.00</span></p></div>
+
+<p><b>Standard Practical Plumbing.</b> By <span class="smcap">R. M. Starbuck</span>.</p>
+
+<div class="blockquot"><p>A complete practical treatise of 450 pages, covering the subject of Modern Plumbing in all its
+branches, a large amount of space being devoted to a very complete and practical treatment of
+the subject of Hot Water Supply and Circulation and Range Boiler Work. Its thirty chapters
+include about every phase of the subject one can think of, making it an indispensable work to
+the master plumber, the journeyman plumber, and the apprentice plumber, containing chapters
+on: the plumber&#8217;s tools; wiping solder; composition and use; joint wiping; lead work;
+traps; siphonage of traps; venting; continuous venting; house sewer and sewer connections;
+house drain; soil piping, roughing; main trap and fresh air inlet; floor, yard, cellar drains,
+rain leaders, etc.; fixture wastes; water closets; ventilation; improved plumbing connections;
+residence plumbing; plumbing for hotels, schools, factories, stables, etc.; modern country
+plumbing; filtration of sewage and water supply; hot and cold supply; range boilers; circulation;
+circulating pipes; range boiler problems; hot water for large buildings; water lift and
+its use; multiple connections for hot water boilers; heating of radiation by supply system;
+theory for the plumber; drawing for the plumber. Fully illustrated by 347 engravings.
+Price <span class="price">$3.00</span></p></div>
+
+<h2>RECIPE BOOK</h2>
+
+<p><b>Henley&#8217;s Twentieth Century Book of Recipes, Formulas and Processes.</b>
+Edited by <span class="smcap">Gardner D. Hiscox</span>.</p>
+
+<div class="blockquot"><p>The most valuable Techno-chemical Formula Book published, including over 10,000 selected
+scientific, chemical, technological, and practical recipes and processes.</p>
+
+<p>This is the most complete Book of Formulas ever published, giving thousands of recipes for
+the manufacture of valuable articles for everyday use. Hints, Helps, Practical Ideas, and
+Secret Processes are revealed within its pages. It covers every branch of the useful arts and
+tells thousands of ways of making money, and is just the book everyone should have at his
+command.</p>
+
+<p>Modern in its treatment of every subject that properly falls within its scope, the book may
+truthfully be said to present the very latest formulas to be found in the arts and industries,
+and to retain those processes which long experience has proven worthy of a permanent record.
+To present here even a limited number of the subjects which find a place in this valuable work
+would be difficult. Suffice to say that in its pages will be found matter of intense interest and
+immeasurably practical value to the scientific amateur and to him who wishes to obtain a
+knowledge of the many processes used in the arts, trades and manufacture, a knowledge
+which will render his pursuits more instructive and remunerative. Serving as a
+reference book to the small and large manufacturer and supplying intelligent seekers with the
+information necessary to conduct a process, the work will be found of inestimable worth to
+the Metallurgist, the Photographer, the Perfumer, the Painter, the Manufacturer of Glues,
+Pastes, Cements, and Mucilages, the Compounder of Alloys, the Cook, the Physician, the
+Druggist, the Electrician, the Brewer, the Engineer, the Foundryman, the Machinist, the
+Potter, the Tanner, the Confectioner, the Chiropodist, the Manicurist, the Manufacturer of
+Chemical Novelties and Toilet Preparations, the Dyer, the Electroplater, the Enameler,
+the Hat Maker, the Ink Manufacturer, the Optician, the Farmer, the Dairyman, the Paper
+Maker, the Wood and Metal Worker, the Chandler and Soap Maker, the Veterinary Surgeon,
+and the Technologist in general.</p>
+
+<p>A mine of information, and up-to-date in every respect. A book which will prove of value
+to EVERYONE, as it covers every branch of the Useful Arts. Every home needs this book;
+every office, every factory, every store, every public and private enterprise&mdash;EVERYWHERE&mdash;should
+have a copy. 800 pages. Price <span class="price">$3.00</span></p>
+
+<h3>WHAT IS SAID OF THIS BOOK:</h3>
+
+<p>&#8220;Your Twentieth Century Book of Recipes, Formulas, and Processes duly received. I am
+glad to have a copy of it, and if I could not replace it, money couldn&#8217;t buy it. It is the best
+thing of the sort I ever saw.&#8221; (Signed) <span class="smcap">M. E. Trux</span>, Sparta, Wis.</p>
+
+<p>&#8220;There are few persons who would not be able to find in the book some single formula that
+would repay several times the cost of the book.&#8221;&mdash;<i>Merchants&#8217; Record and Show Window.</i></p>
+
+<p>&#8220;I purchased your book, &#8216;Henley&#8217;s Twentieth Century Book of Recipes, Formulas and Processes,&#8217;
+about a year ago and it is worth its weight in <i>gold</i>.&#8221;&mdash;<span class="smcap">Wm. H. Murray</span>, Bennington, Vt.</p>
+
+<h3>&#8220;ONE OF THE WORLD&#8217;S MOST USEFUL BOOKS&#8221;</h3>
+
+<p>&#8220;Some time ago I got one of your &#8216;Twentieth Century Books of Formulas,&#8217; and have made
+my living from it ever since. I am alone since my husband&#8217;s death with two small children
+to care for and am trying so hard to support them. I have customers who take from me
+Toilet Articles I put up, following directions given in the book, and I have found everyone of
+them to be fine.&#8221;&mdash;<span class="smcap">Mrs. J. H. McMaken</span>, West Toledo, Ohio.</p></div>
+
+<p class='pagenum'><a name="Page_Cat30" id="Page_Cat30">[30]</a></p>
+
+<h2>RUBBER</h2>
+
+<p><b>Rubber Hand Stamps and the Manipulation of India Rubber.</b> <span class="smcap">By T.
+O&#8217;Conor Sloane</span>.</p>
+
+<div class="blockquot"><p>This book gives full details on all points, treating in a concise and simple manner the elements
+of nearly everything it is necessary to understand for a commencement in any branch of the
+India Rubber Manufacture. The making of all kinds of Rubber Hand Stamps, Small Articles
+of India Rubber, U. S. Government Composition, Dating Hand Stamps, the Manipulation of
+Sheet Rubber, Toy Balloons, India Rubber Solutions, Cements, Blackings, Renovating,
+Varnish, and Treatment for India Rubber Shoes, etc.; the Hektograph Stamp Inks, and Miscellaneous
+Notes, with a Short Account of the Discovery, Collection and Manufacture of India
+Rubber, are set forth in a manner designed to be readily understood, the explanations being
+plain and simple. Including a chapter on Rubber Tire Making and Vulcanizing; also a
+chapter on the uses of rubber in Surgery and Dentistry. 3rd Revised and Enlarged Edition.
+175 pages. Illustrated <span class="price">$1.00</span></p></div>
+
+<h2>SAWS</h2>
+
+<p><b>Saw Filing and Management of Saws.</b> By <span class="smcap">Robert Grimshaw</span>.</p>
+
+<div class="blockquot"><p>A practical hand-book on filing, gumming, swaging, hammering, and the brazing of band
+saws, the speed, work, and power to run circular saws, etc. A handy book for those who have
+charge of saws, or for those mechanics who do their own filing, as it deals with the proper
+shape and pitches of saw teeth of all kinds and gives many useful hints and rules for gumming,
+setting, and filing, and is a practical aid to those who use saws for any purpose. Complete
+tables of proper shape, pitch, and saw teeth as well as sizes and number of teeth of various
+saws are included. 3rd Edition, Revised and Enlarged. Illustrated. Price <span class="price">$1.00</span></p></div>
+
+<h2>STEAM ENGINEERING</h2>
+
+<p><b>American Stationary Engineering.</b> By <span class="smcap">W. E. Crane</span>.</p>
+
+<div class="blockquot"><p>This book begins at the boiler room and takes in the whole power plant. A plain talk on
+every-day work about engines, boilers, and their accessories. It is not intended to be scientific
+or mathematical. All formulas are in simple form so that any one understanding plain
+arithmetic can readily understand any of them. The author has made this the most practical
+book in print; has given the results of his years of experience, and has included about all that
+has to do with an engine room or a power plant. You are not left to guess at a single point.
+You are shown clearly what to expect under the various conditions; how to secure the best
+results; ways of preventing &#8220;shut downs&#8221; and repairs; in short, all that goes to make up the
+requirements of a good engineer, capable of taking charge of a plant. It&#8217;s plain enough for
+practical men and yet of value to those high in the profession.</p>
+
+<p>A partial list of contents is: The boiler room, cleaning boilers, firing, feeding; pumps, inspection
+and repair; chimneys, sizes and cost; piping; mason work; foundations; testing cement;
+pile driving; engines, slow and high speed; valves; valve setting; Corliss engines, setting
+valves, single and double eccentric; air pumps and condensers; different types of condensers;
+water needed; lining up; pounds; pins not square in crosshead or crank; engineers&#8217;
+tools; pistons and piston rings; bearing metal; hardened copper; drip pipes from cylinder
+jacket; belts, how made, care of; oils; greases; testing lubricants; rules and tables, including
+steam tables; areas of segments; squares and square roots; cubes and cube root;
+areas and circumferences of circles. Notes on: Brick work; explosions; pumps; pump
+valves; heaters, economizers; safety valves; lap, lead, and clearance. Has a complete examination
+for a license, etc., etc. 3rd Edition. 345 pages, illustrated. Price <span class="price">$2.00</span></p></div>
+
+<p><b>Engine Runner&#8217;s Catechism.</b> By <span class="smcap">Robert Grimshaw</span>.</p>
+
+<div class="blockquot"><p>A practical treatise for the stationary engineer, telling how to erect, adjust, and run the
+principal steam engines in use in the United States. Describing the principal features of various
+special and well-known makes of engines: Temper Cut-off, Shipping and Receiving Foundations,
+Erecting and Starting, Valve Setting, Care and Use, Emergencies, Erecting and Adjusting
+Special Engines.</p>
+
+<p>The questions asked throughout the catechism are plain and to the point, and the answers
+are given in such simple language as to be readily understood by anyone. All the instructions
+given are complete and up-to-date; and they are written in a popular style, without any
+technicalities or mathematical formul&aelig;. The work is of a handy size for the pocket, clearly
+and well printed, nicely bound, and profusely illustrated.</p>
+
+<p>To young engineers this catechism will be of great value, especially to those who may be
+preparing to go forward to be examined for certificates of competency; and to engineers
+generally it will be of no little service, as they will find in this volume more really practical
+and useful information than is to be found anywhere else within a like compass. 387 pages.
+7th Edition. Price <span class="price">$2.00</span></p></div>
+
+<p><span class='pagenum'><a name="Page_Cat31" id="Page_Cat31">[31]</a></span><b>Modern
+Steam Engineering in Theory and Practice.</b> By <span class="smcap">Gardner D.
+Hiscox</span>.</p>
+
+<div class="blockquot"><p>This is a complete and practical work issued for Stationary Engineers and Firemen, dealing
+with the care and management of boilers, engines, pumps, superheated steam, refrigerating
+machinery, dynamos, motors, elevators, air compressors, and all other branches with which
+the modern engineer must be familiar. Nearly 200 questions with their answers on steam
+and electrical engineering, likely to be asked by the Examining Board, are included.</p>
+
+<p>Among the chapters are: Historical: steam and its properties; appliances for the generation
+of steam; types of boilers; chimney and its work; heat economy of the feed water; steam
+pumps and their work; incrustation and its work; steam above atmospheric pressure; flow
+of steam from nozzles; superheated steam and its work; adiabatic expansion of steam; indicator
+and its work; steam engine proportions; slide valve engines and valve motion; Corliss
+engine and its valve gear; compound engine and its theory; triple and multiple expansion
+engine; steam turbine; refrigeration; elevators and their management; cost of power; steam
+engine troubles; electric power and electric plants. 487 pages, 405 engravings. 3rd Edition.
+Price <span class="price">$3.00</span></p></div>
+
+<p><b>Steam Engine Catechism.</b> By <span class="smcap">Robert Grimshaw</span>.</p>
+
+<div class="blockquot"><p>This unique volume of 413 pages is not only a catechism on the question and answer principle
+but it contains formulas and worked-out answers for all the Steam problems that appertain to
+operation and management of the Steam Engine. Illustrations of various valves and valve
+gear with their principles of operation are given. Thirty-four Tables that are indispensable
+to every engineer and fireman that wishes to be progressive and is ambitious to become master
+of his calling are within its pages. It is a most valuable instructor in the service of Steam
+Engineering. Leading engineers have recommended it as a valuable educator for the beginner
+as well as a reference book for the engineer. It is thoroughly indexed for every detail.
+Every essential question on the Steam Engine with its answer is contained in this valuable
+work. 16th Edition. Price <span class="price">$2.00</span></p></div>
+
+<p><b>Steam Engineer&#8217;s Arithmetic.</b> By <span class="smcap">Colvin-Cheney</span>.</p>
+
+<div class="blockquot"><p>A practical pocket-book for the steam engineer. Shows how to work the problems of the
+engine room and shows &#8220;why.&#8221; Tells how to figure horsepower of engines and boilers; area
+of boilers; has tables of areas and circumferences; steam tables; has a dictionary of engineering
+terms. Puts you on to all of the little kinks in figuring whatever there is to figure around a
+power plant. Tells you about the heat unit; absolute zero; adiabatic expansion; duty of
+engines; factor of safety; and a thousand and one other things; and everything is plain and
+simple&mdash;not the hardest way to figure, but the easiest. 2nd Edition. Price <span class="price">50 Cents</span></p></div>
+
+<p><b>Engine Tests and Boiler Efficiencies.</b> By <span class="smcap">J. Buchetti</span>.</p>
+
+<div class="blockquot"><p>This work fully describes and illustrates the method of testing the power of steam engines,
+turbines and explosive motors. The properties of steam and the evaporative power of fuels.
+Combustion of fuel and chimney draft; with formulas explained or practically computed.
+255 pages, 179 illustrations. Price <span class="price">$3.00</span></p></div>
+
+<p><b>Horsepower Chart.</b></p>
+
+<div class="blockquot"><p>Shows the horsepower of any stationary engine without calculation. No matter what the
+cylinder diameter of stroke, the steam pressure of cut-off, the revolutions, or whether condensing
+or non-condensing, it&#8217;s all there. Easy to use. accurate, and saves time and calculations.
+Especially useful to engineers and designers. Price <span class="price">50 Cents</span></p></div>
+
+<h2>STEAM HEATING AND VENTILATION</h2>
+
+<p><b>Practical Steam, Hot-Water Heating and Ventilation.</b> By <span class="smcap">A. G. King</span>.</p>
+
+<div class="blockquot"><p>This book is the standard and latest work published on the subject and has been prepared for
+the use of all engaged in the business of steam, hot-water heating, and ventilation. It is an
+original and exhaustive work. Tells how to get heating contracts, how to install heating and
+ventilating apparatus, the best business methods to be used, with &#8220;Tricks of the Trade&#8221; for
+shop use. Rules and data for estimating radiation and cost and such tables and information
+as make it an indispensable work for everyone interested in steam, hot-water heating, and
+ventilation. It describes all the principal systems of steam, hot-water, vacuum, vapor, and
+vacuum-vapor heating, together with the new accelerated systems of hot-water circulation,
+including chapters on up-to-date methods of ventilation and the fan or blower system of heating
+and ventilation. Containing chapters on: I. Introduction. II. Heat. III. Evolution
+of artificial heating apparatus. IV. Boiler surface and settings. V. The chimney flue.
+VI. Pipe and fittings. VII. Valves, various kinds. VIII. Forms of radiating surfaces.
+IX.<span class='pagenum' style="font-size: 100%;"><a name="Page_Cat32" id="Page_Cat32">[32]</a></span>
+Locating of radiating surfaces. X. Estimating radiation. XI. Steam-heating apparatus
+XII. Exhaust-steam heating. XIII. Hot-water heating. XIV. Pressure systems of hot-water
+work. XV. Hot-water appliances. XVI. Greenhouse heating. XVII. Vacuum vapor and
+vacuum exhaust heating. XVIII. Miscellaneous heating. XIX. Radiator and pipe connections.
+XX. Ventilation. XXI. Mechanical ventilation and hot-blast heating. XXII.
+Steam appliances. XXIII. District heating. XXIV. Pipe and boiler covering. XXV. Temperature
+regulation and heat control. XXVI. Business methods. XXVII. Miscellaneous.
+XXVIII. Rules, tables, and useful information. 367 pages, 300 detailed engravings. 2nd
+Edition&mdash;Revised. Price <span class="price">$3.00</span></p></div>
+
+<p><b>Five Hundred Plain Answers to Direct Questions on Steam, Hot-Water,
+Vapor and Vacuum Heating Practice.</b> By <span class="smcap">Alfred G. King</span>.</p>
+
+<div class="blockquot"><p>This work, just off the press, is arranged in question and answer form; it is intended as a
+guide and text-book for the younger, inexperienced fitter and as a reference book for all
+fitters. This book tells &#8220;how&#8221; and also tells &#8220;why&#8221;. No work of its kind has ever been
+published. It answers all the questions regarding each method or system that would be
+asked by the steam fitter or heating contractor, and may be used as a text or reference book,
+and for examination questions by Trade Schools or Steam Fitters&#8217; Associations. Rules, data,
+tables and descriptive methods are given, together with much other detailed information of
+daily practical use to those engaged in or interested in the various methods of heating. Valuable
+to those preparing for examinations. Answers every question asked relating to modern
+Steam, Hot-Water, Vapor and Vacuum Heating. Among the contents are: The Theory and
+Laws of Heat. Methods of Heating. Chimneys and Flues. Boilers for Heating. Boiler
+Trimmings and Settings. Radiation. Steam Heating. Boiler, Radiator and Pipe Connections
+for Steam Heating. Hot Water Heating. The Two-Pipe Gravity System of Hot Water
+Heating. The Circuit System of Hot Water Heating. The Overhead System of Hot Water
+Heating. Boiler, Radiator and Pipe Connections for Gravity Systems of Hot Water Heating.
+Accelerated Hot Water Heating. Expansion Tank Connections. Domestic Hot Water
+Heating. Valves and Air Valves. Vacuum Vapor and Vacuo-Vapor Heating. Mechanical
+Systems of Vacuum Heating. Non-Mechanical Vacuum Systems. Vapor Systems. Atmospheric
+and Modulating Systems. Heating Greenhouses. Information, Rules and Tables.
+200 pages, 127 illustrations. Octavo. Cloth. Price <span class="price">$1.50</span></p></div>
+
+<h2>STEEL</h2>
+
+<p><b>Steel: Its Selection, Annealing, Hardening, and Tempering.</b> By <span class="smcap">E. R.
+Markham</span>.</p>
+
+<div class="blockquot"><p>This work was formerly known as &#8220;The American Steel Worker,&#8221; but on the publication
+of the new, revised edition, the publishers deemed it advisable to change its title to a more
+suitable one. It is the standard work on Hardening, Tempering, and Annealing Steel of all kinds.
+This book tells how to select, and how to work, temper, harden, and anneal steel for everything
+on earth. It doesn&#8217;t tell how to temper one class of tools and then leave the treatment
+of another kind of tool to your imagination and judgment, but it gives careful instructions
+for every detail of every tool, whether it be a tap, a reamer or just a screw-driver. It tells
+about the tempering of small watch springs, the hardening of cutlery, and the annealing of
+dies. In fact, there isn&#8217;t a thing that a steel worker would want to know that isn&#8217;t included.
+It is the standard book on selecting, hardening and tempering all grades of steel. Among
+the chapter headings might be mentioned the following subjects: Introduction; the workman;
+steel; methods of heating; heating tool steel; forging; annealing; hardening baths;
+baths for hardening; hardening steel; drawing the temper after hardening; examples of
+hardening; pack hardening; case hardening; spring tempering; making tools of machine
+steel; special steels; steel for various tools; causes of trouble; high-speed steels, etc. 400
+pages. Very fully illustrated. Fourth edition. Price <span class="price">$2.50</span></p></div>
+
+<p><b>Hardening, Tempering, Annealing, and Forging of Steel.</b> By <span class="smcap">J. V. Woodworth</span>.</p>
+
+<div class="blockquot"><p>A new work treating in a clear, concise manner all modern processes for the heating, annealing,
+forging, welding, hardening and tempering of steel, making it a book of great practical
+value to the metal-working mechanic in general, with special directions for the successful
+hardening and tempering of all steel tools used in the arts, including milling cutters, taps, thread
+dies, reamers, both solid and shell, hollow mills, punches and dies, and all kinds of sheet-metal
+working tools, shear blades, saws, fine cutlery, and metal-cutting tools of all description,
+as well as for all implements of steel both large and small. In this work the simplest
+and most satisfactory hardening and tempering processes are given.</p>
+
+<p>The uses to which the leading brands of steel may be adapted are concisely presented, and
+their treatment for working under different conditions explained, also the special methods
+for the hardening and tempering of special brands.</p>
+
+<p>A chapter devoted to the different processes for case-hardening is also included, and special
+reference made to the adaptation of machinery steel for tools of various kinds, Fourth edition.
+288 pages. 201 illustrations. Price <span class="price">$2.50</span></p></div>
+
+<p><span class='pagenum'><a name="Page_Cat33" id="Page_Cat33">[33]</a></span></p>
+
+<h2>TRACTORS</h2>
+
+<p><b>The Modern Gas Tractor.</b> By <span class="smcap">Victor W. Pag&eacute;</span>, M.E.</p>
+
+<div class="blockquot"><p>A complete treatise describing all types and sizes of gasoline, kerosene and oil tractors. Considers
+design and construction exhaustively, gives complete instructions for care, operation
+and repair, outlines all practical applications on the road and in the field. The best and
+latest work on farm tractors and tractor power plants. A work needed by farmers, students,
+blacksmiths, mechanics, salesmen, implement dealers, designers, and engineers. Second edition,
+revised and enlarged. 504 pages. Nearly 300 illustrations and folding plates. Price <span class="price">$2.00</span></p></div>
+
+<h2>TURBINES</h2>
+
+<p><b>Marine Steam Turbines.</b> By <span class="smcap">Dr. G. Bauer</span> and <span class="smcap">O. Lasche</span>. Assisted by
+<span class="smcap">E. Ludwig</span> and <span class="smcap">H. Vogel</span>.</p>
+
+<div class="blockquot"><p>Translated from the German and edited by M. G. S. Swallow. The book is essentially practical
+and discusses turbines in which the full expansion of steam passes through a number
+of separate turbines arranged for driving two or more shafts, as in the Parsons system, and
+turbines in which the complete expansion of steam from inlet to exhaust pressure occurs in
+a turbine on one shaft, as in the case of the Curtis machines. It will enable a designer to
+carry out all the ordinary calculation necessary for the construction of steam turbines, hence
+it fills a want which is hardly met by larger and more theoretical works. Numerous tables,
+curves and diagrams will be found, which explain with remarkable lucidity the reason why
+turbine blades are designed as they are, the course which steam takes through turbines of
+various types, the thermodynamics of steam turbine calculation, the influence of vacuum
+on steam consumption of steam turbines, etc. In a word, the very information which a designer
+and builder of steam turbines most requires. Large octavo, 214 pages. Fully illustrated
+and containing eighteen tables, including an entropy chart. Price, net <span class="price">$3.50</span></p></div>
+
+<h2>WATCH MAKING</h2>
+
+<p><b>Watchmaker&#8217;s Handbook.</b> By <span class="smcap">Claudius Saunier</span>.</p>
+
+<div class="blockquot"><p>No work issued can compare with this book for clearness and completeness. It contains
+498 pages and is intended as a workshop companion for those engaged in watch-making and
+allied mechanical arts. Nearly 250 engravings and fourteen plates are included. This is
+the standard work on watch-making. Price <span class="price">$3.00</span></p></div>
+
+<h2>WELDING</h2>
+
+<p><b>Automobile Welding with the Oxy-Acetylene Flame.</b> By <span class="smcap">M. Keith Dunham</span>.</p>
+
+<div class="blockquot"><p>Explains in a simple manner apparatus to be used, its care, and how to construct necessary
+shop equipment. Proceeds then to the actual welding of all automobile parts, in a manner
+understandable by every one. <i>Gives principles never to be forgotten.</i> Aluminum, cast iron,
+steel, copper, brass, bronze, and malleable iron are fully treated, as well as a clear explanation
+of the proper manner to burn the carbon out of the combustion head. This book is of
+utmost value, since the perplexing problems arising when metal is heated to a melting point
+are fully explained and the proper methods to overcome them shown. 167 pages, fully illustrated.
+Price <span class="price">$1.00</span></p></div>
+
+<hr class="c25" />
+
+<p class="pagenum"><a name="Page_Cat34" id="Page_Cat34"></a></p>
+
+<div class="boxoutside" style="margin: 1.5em 10%;"><div class="boxinside">
+<p class="center fsize125">Every Practical Man Needs A Magazine Which<br />
+Will Tell Him How To Make And Do Things</p>
+</div></div>
+
+<p class="center" style="margin: 1.5em 10%;"><i><b>Have us enter your subscription to the best mechanical
+magazine on the market. Only one dollar
+a year for twelve numbers. Subscribe today to</b></i></p>
+
+<p class="center fsize175"><b>Everyday Engineering</b></p>
+
+<div class="blockquot"><p>A monthly magazine devoted to practical mechanics for everyday men.
+Its aim is to popularize engineering as a science, teaching the elements
+of applied mechanics and electricity in a straightforward and understandable
+manner. The magazine maintains its own experimental laboratory where
+the devices described in articles submitted to the Editor are first tried out and
+tested before they are published. This important innovation places the standard
+of the published material very high, and it insures accuracy and dependability.</p>
+
+<p>The magazine is the only one in this country that specializes in practical
+model building. Articles in past issues have given comprehensive designs for
+many model boats, including submarines and chasers, model steam and gasoline
+engines, electric motors and generators, etc., etc. This feature is a permanent
+one in this magazine.</p>
+
+<p>Another popular department is that devoted to automobiles and airplanes.
+Care, maintenance, and operation receive full and authoritative treatment. Every
+article is written from the practical, everyday man, standpoint rather than from
+that of the professional.</p>
+
+<p>The magazine entertains while it instructs. It is a journal of practical, dependable
+information given in such a style that it may be readily assimilated
+and applied by the man with little or no technical training. The aim is to place
+before the man who leans toward practical mechanics, a series of concise, crisp,
+readable talks on what is going on and <i>how it is done</i>. These articles are profusely
+illustrated with clear, snappy photographs, specially posed to illustrate the subject
+in the magazine&#8217;s own studio by its own staff of technically-trained illustrators
+and editors.</p>
+
+<p><b>The subscription price of the magazine is one dollar per year of twelve numbers.
+Sample copy sent on receipt of ten cents.</b></p>
+
+<p>Enter your subscription to this practical magazine with your bookseller.</p></div>
+
+<p class="center fsize150"><b>The Norman W. Henley Publishing Co.,</b></p>
+
+<p class="center"><b>2 West 45th Street, New York</b></p>
+
+<hr class="c25" style="margin-bottom: 2.5em;" />
+
+<div class="bbox" style="margin: 1em auto; padding: 1em;">
+
+<h2><a name="TN" id="TN"></a>Transcriber&#8217;s Notes</h2>
+
+<p>General remarks:</p>
+<ul>
+  <li>Where the small illustrations are not clear enough to see all details in the drawings, hyperlinks in the left margin link to larger
+      scale images.</li>
+  <li>Some page numbers are missing due to full-page illustrations having been moved around.</li>
+  <li>There are some differences in wording between the Table of Contents, the lists of sections per chapter, and the actual section
+      titles. Their meaning is clear, and they have been left as they were in the original work. The hyperlinks link to the proper sections
+      or paragraphs.</li>
+  <li>Some in-line multi-line formulas have been transcribed as single-line formulas, where necessary with brackets added.</li>
+  <li>Page 56, table: Fig. 8 in the first column does not refer to Fig. 8 in this work.</li>
+  <li>Page 186, Fig. 67: the dimensions in the lower right corner are partly illegible, they possibly read <i>(4) <span
+      class="nowrap"><sup>3</sup>&#8260;<sub>8</sub>&#8242;&#8242;</span> 16 Tap <span
+      class="nowrap"><sup>1</sup>&#8260;<sub>2</sub>&#8242;&#8242;</span> Deep U. S. St'd. Threads</i>.</li>
+  <li>The original work does not have a Figure 89.</li>
+  <li>Page 283, Fig. 113: the dimension <span class="nowrap">4&#8242;&#8242;</span> should probably refer to the cylinder diameter (if
+      drawing is to scale), not to the cylinder diameter plus part of the large valve as in the drawing.</li>
+  <li>Page 303, table: it is uncertain what <i>free with kerosene</i> means, there may be a word omitted.</li>
+  <li>Page 544, entirely censored. It is not clear what this page originally contained (possibly a table), since text and numbering of
+      illustrations are uninterrupted. The text <i>CENSORED</i> has been moved to after the first paragraph of the section on Mercedes
+      Engines.</li>
+  <li>The List of Illustrations does not occur in the original work.</li>
+</ul>
+
+<p>Changes made:</p>
+<ul>
+  <li>The text of the original work (including inconsistencies in accents, spelling, hyphenation and lay-out, and differences between the
+      main text, illustrations and advertisements) has been followed, except when listed below. Only some minor obvious typographical
+      errors have been corrected silently.</li>
+  <li>Where the author used <i>x</i> for multiplication, this has been replaced by <i>&times;</i> in the body of the text (not in the
+      advertisements or illustrations).</li>
+  <li>The illustrations have been moved so as not to disrupt the flow of the text.</li>
+  <li>Engine and aircraft types are not always named consistently in the original; Curtiss engine O X 2, OX-2, 0X2 and 0 X 2 have all been
+      changed to OX-2, Curtiss aircraft JN4 and JN-4 to JN-4.</li>
+  <li>Multi-page tables: repeated headings have been removed, and the tables treated as one consecutive table.</li>
+  <li>Page 22: <i>The product of</i> has been moved into the first formula.</li>
+  <li>Page 25: <i>When B &times; r = M</i> changed to <i>When P &times; r = M</i>.</li>
+  <li>Page 74: <i>.225 &divide; 775 = .2905</i> changed to <i>.225 &divide; .775 = .2905</i>.</li>
+  <li>Page 137 (caption): <i>Bavary</i> changed to <i>Baverey</i> as elsewhere.</li>
+  <li>Page 172: <i>evidently</i> changed to <i>evident</i>.</li>
+  <li>Page 214: <i>drop to O</i> (capital o) changed to <i>drop to 0</i> (zero).</li>
+  <li>Page 248: <i>actual from a common</i> changed to <i>actuated from a common</i>.</li>
+  <li>Page 256: <i>values</i> changed to <i>valves</i>.</li>
+  <li>Page 280: <i>Fig. 6</i> changed to <i>Fig. 112</i>.</li>
+  <li>Page 306: <i>Fig. 127, B</i> changed to <i>Fig. 127, C</i> (2nd reference).</li>
+  <li>Page 324: <i>Rhone</i> changed to <i>Le Rhone</i> as elsewhere.</li>
+  <li>Page 334: <i>Check values</i> changed to <i>Check valves</i>.</li>
+  <li>Page 364: <i>LeRhone changed</i> to <i>Le Rhone</i> as elsewhere.</li>
+  <li>Page 390: <i>Fig. 62, D</i> changed to <i>Fig. 168, B</i>.</li>
+  <li>Page 408: <i>Stilson</i> changed to <i>Stillson</i> as elsewhere.</li>
+  <li>Page 490: <i>both valves</i> changed to <i>both halves</i>.</li>
+  <li>Page 514: <i>standard ratio is 5.3</i> changed to <i>standard ratio is 5:3</i>.</li>
+  <li>Page 529: <i>gallons per minute 1,400 R. P. M.</i> changed to <i>gallons per minute at 1,400 R. P. M.</i></li>
+  <li>Page 546: <i>Hispano Suiza</i> changed to <i>Hispano-Suiza</i> as elsewhere.</li>
+  <li>Page 556: <i>Diameter of crank-shaft, 56 mm.</i> changed to <i>Diameter of crank-shaft, 55 mm.</i></li>
+  <li>Page 7 (advertisements): <i>Hazlehurst Field</i> changed to <i>Hazelhurst Field</i>.</li>
+  <li>Page 21 (advertisements): <i>Rhose Island Compound</i> changed to <i>Rhode Island Compound</i>.</li>
+  <li>Index: <i>Shebler</i> changed to <i>Schebler</i>, <i>camshaft</i> changed to <i>cam-shaft</i>, <i>wristpin</i> changed to
+      <i>wrist-pin</i>, etc. (all as in text).</li>
+</ul>
+</div>
+
+<p>&nbsp;</p>
+<p>&nbsp;</p>
+<hr class="full" />
+<p>***END OF THE PROJECT GUTENBERG EBOOK AVIATION ENGINES***</p>
+<p>******* This file should be named 38187-h.txt or 38187-h.zip *******</p>
+<p>This and all associated files of various formats will be found in:<br />
+<a href="http://www.gutenberg.org/dirs/3/8/1/8/38187">http://www.gutenberg.org/3/8/1/8/38187</a></p>
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+*** END: FULL LICENSE ***
+</pre>
+</body>
+</html>
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@@ -0,0 +1,19612 @@
+The Project Gutenberg eBook, Aviation Engines, by Victor Wilfred Pagé
+
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+
+
+
+Title: Aviation Engines
+       Design--Construction--Operation and Repair
+
+
+Author: Victor Wilfred Pagé
+
+
+
+Release Date: December 2, 2011  [eBook #38187]
+
+Language: English
+
+Character set encoding: ISO-646-US (US-ASCII)
+
+
+***START OF THE PROJECT GUTENBERG EBOOK AVIATION ENGINES***
+
+
+E-text prepared by Juliet Sutherland, Harry Lamé, and the Online
+Distributed Proofreading Team (http://www.pgdp.net)
+
+
+
+Note: Project Gutenberg also has an HTML version of this
+      file which includes the original illustrations.
+      See 38187-h.htm or 38187-h.zip:
+      (http://www.gutenberg.org/files/38187/38187-h/38187-h.htm)
+      or
+      (http://www.gutenberg.org/files/38187/38187-h.zip)
+
+
+      +-----------------------------------------------------------------+
+      |                      TRANSCRIBER'S NOTES                        |
+      |                                                                 |
+      | Transcription used for this e-text:                             |
+      |   Italic text in the original work is transcribed between       |
+      |   underscores, as in _text_;                                    |
+      |   Bold face text in the original work is transcribed between    |
+      |   equal signs, as in =text=;                                    |
+      |   Bold face underlined text in the original work is transcribed |
+      |   between tildes, as in ~text~;                                 |
+      |   Super- and subscripts in the original work are transcribed as |
+      |   ^{text} and _{text}, respectively;                            |
+      |   Greek characters have been transcribed as [alpha], [beta],    |
+      |   etc.;                                                         |
+      |   The oe-ligature in Phoenix has been transcribed as oe.        |
+      |                                                                 |
+      | Some in-line multi-line formulas have been transcribed as       |
+      | single-line formulas, where necessary with brackets added.      |
+      |                                                                 |
+      | Some table headings have been replaced by legends [A], [B], etc;|
+      | these are listed directly above the relevant tables.            |
+      |                                                                 |
+      | More extensive Transcriber's Notes may be found at the end of   |
+      | this text.                                                      |
+      +-----------------------------------------------------------------+
+
+
+
+
+
+AVIATION ENGINES
+
+Design--Construction--Operation and Repair
+
+by
+
+FIRST LIEUT. VICTOR W. PAGE, A. S. S. C., U. S. R.
+
+
+      *      *      *      *      *
+
+
+~JUST PUBLISHED~
+
+
+=AVIATION ENGINES. Their Design, Construction, Operation and Repair.=
+
+    By Lieut. VICTOR W. PAGE, Aviation Section, S.C.U.S.R.
+
+    A practical work containing valuable instructions for aviation
+    students, mechanicians, squadron engineering officers and all
+    interested in the construction and upkeep of airplane power
+    plants. 576 octavo pages. 250 illustrations. Price $3.00.
+
+
+=AVIATION CHART, or the Location of Airplane Power Plant Troubles Made
+Easy.=
+
+    By Lieut. VICTOR W. PAGE, A.S., S.C.U.S.R.
+
+    A large chart outlining all parts of a typical airplane power
+    plant, showing the points where trouble is apt to occur and
+    suggesting remedies for the common defects. Intended especially
+    for aviators and aviation mechanics on school and field duty.
+    Price 50 cents.
+
+
+=GLOSSARY OF AVIATION TERMS.=
+
+    Compiled by Lieuts. VICTOR W. PAGE, A.S., S.C.U.S.R. and PAUL
+    MONTARIOL of the French Flying Corps on duty at Signal Corps
+    Aviation School, Mineola, L. I.
+
+    A complete glossary of practically all terms used in aviation,
+    having lists in both French and English, with equivalents in
+    either language. A very valuable book for all who are about to
+    leave for duty overseas. Price, cloth, $1.00.
+
+
+=THE NORMAN W. HENLEY PUBLISHING COMPANY=
+
+2 WEST 45TH ST., NEW YORK
+
+      *      *      *      *      *
+
+
+[Illustration: Part Sectional View of Hall-Scott Airplane Motor, Showing
+Principal Parts.]
+
+
+      *      *      *      *      *
+
+CENSORED
+
+This Book Entitled
+
+AVIATION ENGINES
+
+By LIEUT. VICTOR W. PAGE
+
+has been censored by the United States Government, and pages and
+parts of pages have been omitted by special instructions from
+Washington.
+
+The book has been passed by THE COMMITTEE ON PUBLIC INFORMATION
+and is as complete as we can furnish it, and we so advise the
+purchaser of it.
+
+THE NORMAN W. HENLEY PUBLISHING COMPANY
+
+
+      *      *      *      *      *
+
+
+AVIATION ENGINES
+
+Design--Construction--Operation and Repair
+
+A Complete, Practical Treatise Outlining Clearly
+the Elements of Internal Combustion Engineering
+with Special Reference to the Design, Construction,
+Operation and Repair of Airplane Power
+Plants; Also the Auxiliary Engine Systems, Such
+as Lubrication, Carburetion, Ignition and Cooling.
+
+It Includes Complete Instructions for Engine
+Repairing and Systematic Location of Troubles,
+Tool Equipment and Use of Tools, Also Outlines
+the Latest Mechanical Processes.
+
+by
+
+FIRST LIEUT. VICTOR W. PAGE, A. S. S. C., U. S. R.
+
+Assistant Engineering Officer, Signal Corps Aviation School,
+Mineola, L. I.
+
+Author of "The Modern Gasoline Automobile," Etc.
+
+[Illustration]
+
+Contains Valuable Instructions for All Aviation Students,
+Mechanicians, Squadron Engineering Officers and All Interested in
+the Construction and Upkeep of Airplane Power Plants.
+
+
+
+
+
+
+
+New York
+The Norman W. Henley Publishing Company
+2 West 45th Street
+1917
+
+Copyrighted, 1917
+By
+The Norman W. Henley Publishing Co.
+
+Printed in U. S. A.
+
+All Illustrations in This Book Have Been
+Specially Made by the Publishers, and Their
+Use, Without Permission, Is Strictly Prohibited
+
+Composition, Electrotyping and Presswork
+by the Publishers Printing Co., New York
+
+
+
+
+PREFACE
+
+
+In presenting this treatise on "Aviation Engines," the writer realizes
+that the rapidly developing art makes it difficult to outline all latest
+forms or describe all current engineering practice. This exposition has
+been prepared primarily for instruction purposes and is adapted for men
+in the Aviation Section, Signal Corps, and students who wish to become
+aviators or aviation mechanicians. Every effort has been made to have
+the engineering information accurate, but owing to the diversity of
+authorities consulted and use of data translated from foreign language
+periodicals, it is expected that some slight errors will be present. The
+writer wishes to acknowledge his indebtedness to such firms as the
+Curtiss Aeroplane and Motor Co., Hall-Scott Company, Thomas-Morse
+Aircraft Corporation and General Vehicle Company for photographs and
+helpful descriptive matter. Special attention has been paid to
+instructions on tool equipment, use of tools, trouble "shooting" and
+engine repairs, as it is on these points that the average aviation
+student is weakest. Only such theoretical consideration of
+thermo-dynamics as was deemed absolutely necessary to secure a proper
+understanding of engine action after consulting several instructors is
+included, the writer's efforts having been confined to the preparation
+of a practical series of instructions that would be of the greatest
+value to those who need a diversified knowledge of internal-combustion
+engine operation and repair, and who must acquire it quickly. The
+engines described and illustrated are all practical forms that have been
+fitted to airplanes capable of making flights and may be considered
+fairly representative of the present state of the art.
+
+VICTOR W. PAGE,
+
+_1st Lieut. A. S. S. C., U. S. R_.
+
+MINEOLA, L. I.,
+
+October, 1917.
+
+
+
+
+CONTENTS
+
+
+                                                                   PAGES
+  CHAPTER I
+
+  Brief Consideration of Aircraft Types--Essential Requirements of
+  Aerial Motors--Aviation Engines Must Be Light--Factors Influencing
+  Power Needed--Why Explosive Motors Are Best--Historical--Main
+  Types of Internal Combustion Engines                             17-36
+
+  CHAPTER II
+
+  Operating Principles of Two- and Four-Stroke Engines--Four-cycle
+  Action--Two-cycle Action--Comparing Two- and Four-cycle Types--
+  Theory of Gas and Gasoline Engine--Early Gas-Engine Forms--
+  Isothermal Law--Adiabatic Law--Temperature Computations--Heat and
+  Its Work--Conversion of Heat to Power--Requisites for Best Power
+  Effect                                                           37-59
+
+  CHAPTER III
+
+  Efficiency of Internal Combustion Engines--Various Measures of
+  Efficiency--Temperatures and Pressures--Factors Governing Economy
+  --Losses in Wall Cooling--Value of Indicator Cards--Compression in
+  Explosive Motors--Factors Limiting Compression--Causes of Heat
+  Losses and Inefficiency--Heat Losses to Cooling Water            60-79
+
+  CHAPTER IV
+
+  Engine Parts and Functions--Why Multiple Cylinder Engines Are Best
+  --Describing Sequence of Operations--Simple Engines--Four and Six
+  Cylinder Vertical Tandem Engines--Eight and Twelve Cylinder V
+  Engines--Radial Cylinder Arrangement--Rotary Cylinder Forms     80-109
+
+  CHAPTER V
+
+  Properties of Liquid Fuels--Distillates of Crude Petroleum--
+  Principles of Carburetion Outlined--Air Needed to Burn Gasoline--
+  What a Carburetor Should Do--Liquid Fuel Storage and Supply--
+  Vacuum Fuel Feed--Early Vaporizer Forms--Development of Float Feed
+  Carburetor--Maybach's Early Design--Concentric Float and Jet Type
+  --Schebler Carburetor--Claudel Carburetor--Stewart Metering Pin
+  Type--Multiple Nozzle Vaporizers--Two-Stage Carburetor--Master
+  Multiple Jet Type--Compound Nozzle Zenith Carburetor--Utility of
+  Gasoline Strainers--Intake Manifold Design and Construction--
+  Compensating for Various Atmospheric Conditions--How High
+  Altitude Affects Power--The Diesel System--Notes on Carburetor
+  Installation--Notes on Carburetor Adjustment                   110-154
+
+  CHAPTER VI
+
+  Early Ignition Systems--Electrical Ignition Best--Fundamentals of
+  Magnetism Outlined--Forms of Magneto--Zones of Magnetic Influence
+  --How Magnets are Made--Electricity and Magnetism Related--Basic
+  Principles of Magneto Action--Essential Parts of Magneto and
+  Functions--Transformer Coil Systems--True High Tension Type--The
+  Berling Magneto--Timing and Care--The Dixie Magneto--Spark-Plug
+  Design and Application--Two-Spark Ignition--Special Airplane
+  Plug                                                           155-200
+
+  CHAPTER VII
+
+  Why Lubrication Is Necessary--Friction Defined--Theory of
+  Lubrication--Derivation of Lubricants--Properties of Cylinder Oils
+  --Factors Influencing Lubrication System Selection--Gnome Type
+  Engines Use Castor Oil--Hall-Scott Lubrication System--Oil Supply
+  by Constant Level Splash System--Dry Crank-Case System Best for
+  Airplane Engines--Why Cooling Systems Are Necessary--Cooling
+  Systems Generally Applied--Cooling by Positive Pump Circulation--
+  Thermo-Syphon System--Direct Air-Cooling Methods--Air-Cooled
+  Engine Design Considerations                                   201-232
+
+  CHAPTER VIII
+
+  Methods of Cylinder Construction--Block Castings--Influence on
+  Crank-Shaft Design--Combustion Chamber Design--Bore and Stroke
+  Ratio--Meaning of Piston Speed--Advantage of Off-Set Cylinders--
+  Valve Location of Vital Import--Valve Installation Practice--Valve
+  Design and Construction--Valve Operation--Methods of Driving
+  Cam-Shaft--Valve Springs--Valve Timing--Blowing Back--Lead Given
+  Exhaust Valve--Exhaust Closing, Inlet Opening--Closing the
+  Inlet Valve--Time of Ignition--How an Engine is Timed--Gnome
+  "Monosoupape" Valve Timing--Springless Valves--Four Valves per
+  Cylinder                                                       233-286
+
+  CHAPTER IX
+
+  Constructional Details of Pistons--Aluminum Cylinders and Pistons
+  --Piston Ring Construction--Leak Proof Piston Rings--Keeping Oil
+  Out of Combustion Chamber--Connecting Rod Forms--Connecting Rods
+  for Vee Engines--Cam-Shaft and Crank-Shaft Designs--Ball Bearing
+  Crank-Shafts--Engine Base Construction                         287-323
+
+  CHAPTER X
+
+  Power Plant Installation--Curtiss OX-2 Engine Mounting and
+  Operating Rules--Standard S. A. E. Engine Bed Dimensions--
+  Hall-Scott Engine Installation and Operation--Fuel System Rules
+  --Ignition System--Water System--Preparations to Start Engine--
+  Mounting Radial and Rotary Engines--Practical Hints to Locate
+  Engine Troubles--All Engine Troubles Summarized--Location of
+  Engine Troubles Made Easy                                      324-375
+
+  CHAPTER XI
+
+  Tools for Adjusting and Erecting--Forms of Wrenches--Use and Care
+  of Files--Split Pin Removal and Installation--Complete Chisel Set
+  --Drilling Machines--Drills, Reamers, Taps and Dies--Measuring
+  Tools--Micrometer Calipers and Their Use--Typical Tool Outfits
+  --Special Hall-Scott Tools--Overhauling Airplane Engines--Taking
+  Engine Down--Defects in Cylinders--Carbon Deposits, Cause and
+  Prevention--Use of Carbon Scrapers--Burning Out Carbon with
+  Oxygen --Repairing Scored Cylinders--Valve Removal and Inspection
+  --Reseating and Truing Valves--Valve Grinding Processes--
+  Depreciation in Valve Operating System--Piston Troubles--Piston
+  Ring Manipulation--Fitting Piston Rings--Wrist-Pin Wear--
+  Inspection and Refitting of Engine Bearings--Scraping Brasses to
+  Fit--Fitting Connecting Rods--Testing for Bearing Parallelism--
+  Cam-Shafts and Timing Gears--Precautions in Reassembling Parts 376-456
+
+  CHAPTER XII
+
+  Aviation Engine Types--Division in Classes--Anzani Engines--Canton
+  and Unne Engine--Construction of Gnome Engines--"Monosoupape"
+  Gnome--German "Gnome" Type--Le Rhone Engine--Renault Air-Cooled
+  Engine--Simplex Model "A" Hispano-Suiza--Curtiss Aviation Motors--
+  Thomas-Morse Model 88 Engine--Duesenberg Engine--Aeromarine
+  Six-Cylinder--Wisconsin Aviation Engines--Hall-Scott Engines--
+  Mercedes Motor--Benz Motor--Austro-Daimler Engine--Sunbeam-Coatalen
+  --Indicating and Measuring Instruments--Air Starting Systems--
+  Electric Starting--Battery Ignition                            457-571
+
+  INDEX                                                              573
+
+  LIST OF ILLUSTRATIONS
+
+
+
+
+AVIATION ENGINES
+
+DESIGN--CONSTRUCTION--REPAIR
+
+
+
+
+CHAPTER I
+
+    Brief Consideration of Aircraft Types--Essential Requirements of
+    Aerial Motors--Aviation Engines Must Be Light--Factors
+    Influencing Power Needed--Why Explosive Motors Are Best--
+    Historical--Main Types of Internal Combustion Engines.
+
+
+BRIEF CONSIDERATION OF AIRCRAFT TYPES
+
+The conquest of the air is one of the most stupendous achievements of
+the ages. Human flight opens the sky to man as a new road, and because
+it is a road free of all obstructions and leads everywhere, affording
+the shortest distance to any place, it offers to man the prospect of
+unlimited freedom. The aircraft promises to span continents like
+railroads, to bridge seas like ships, to go over mountains and forests
+like birds, and to quicken and simplify the problems of transportation.
+While the actual conquest of the air is an accomplishment just being
+realized in our days, the idea and yearning to conquer the air are old,
+possibly as old as intellect itself. The myths of different races tell
+of winged gods and flying men, and show that for ages to fly was the
+highest conception of the sublime. No other agent is more responsible
+for sustained flight than the internal combustion motor, and it was only
+when this form of prime mover had been fully developed that it was
+possible for man to leave the ground and alight at will, not depending
+upon the caprices of the winds or lifting power of gases as with the
+balloon. It is safe to say that the solution of the problem of flight
+would have been attained many years ago if the proper source of power
+had been available as all the essential elements of the modern
+aeroplane and dirigible balloon, other than the power plant, were known
+to early philosophers and scientists.
+
+Aeronautics is divided into two fundamentally different
+branches--aviatics and aerostatics. The first comprises all types of
+aeroplanes and heavier than air flying machines such as the helicopters,
+kites, etc.; the second includes dirigible balloons, passive balloons
+and all craft which rise in the air by utilizing the lifting force of
+gases. Aeroplanes are the only practical form of heavier-than-air
+machines, as the helicopters (machines intended to be lifted directly
+into the air by propellers, without the sustaining effect of planes),
+and ornithopters, or flapping wing types, have not been thoroughly
+developed, and in fact, there are so many serious mechanical problems to
+be solved before either of these types of air craft will function
+properly that experts express grave doubts regarding the practicability
+of either. Aeroplanes are divided into two main types--monoplanes or
+single surface forms, and bi-planes or machines having two sets of
+lifting surfaces, one suspended over the other. A third type, the
+triplane, is not very widely used.
+
+Dirigible balloons are divided into three classes: the rigid, the
+semi-rigid, and the non-rigid. The rigid has a frame or skeleton of
+either wood or metal inside of the bag, to stiffen it; the semi-rigid is
+reinforced by a wire net and metal attachments; while the non-rigid is
+just a bag filled with gas. The aeroplane, more than the dirigible and
+balloon, stands as the emblem of the conquest of the air. Two reasons
+for this are that power flight is a real conquest of the air, a real
+victory over the battling elements; secondly, because the aeroplane, or
+any flying machine that may follow, brings air travel within the reach
+of everybody. In practical development, the dirigible may be the
+steamship of the air, which will render invaluable services of a certain
+kind, and the aeroplane will be the automobile of the air, to be used by
+the multitude, perhaps for as many purposes as the automobile is now
+being used.
+
+
+ESSENTIAL REQUIREMENTS OF AERIAL MOTORS
+
+One of the marked features of aircraft development has been the effect
+it has had upon the refinement and perfection of the internal combustion
+motor. Without question gasoline-motors intended for aircraft are the
+nearest to perfection of any other type yet evolved. Because of the
+peculiar demands imposed upon the aeronautical motor it must possess all
+the features of reliability, economy and efficiency now present with
+automobile or marine engines and then must have distinctive points of
+its own. Owing to the unstable nature of the medium through which it is
+operated and the fact that heavier-than-air machines can maintain flight
+only as long as the power plant is functioning properly, an airship
+motor must be more reliable than any used on either land or water. While
+a few pounds of metal more or less makes practically no difference in a
+marine motor and has very little effect upon the speed or hill-climbing
+ability of an automobile, an airship motor must be as light as it is
+possible to make it because every pound counts, whether the motor is to
+be fitted into an aeroplane or in a dirigible balloon.
+
+Airship motors, as a rule, must operate constantly at high speeds in
+order to obtain a maximum power delivery with a minimum piston
+displacement. In automobiles, or motor boats, motors are not required to
+run constantly at their maximum speed. Most aircraft motors must
+function for extended periods at speed as nearly the maximum as
+possible. Another thing that militates against the aircraft motor is the
+more or less unsteady foundation to which it is attached. The
+necessarily light framework of the aeroplane makes it hard for a motor
+to perform at maximum efficiency on account of the vibration of its
+foundation while the craft is in flight. Marine and motor car engines,
+while not placed on foundations as firm as those provided for stationary
+power plants, are installed on bases of much more stability than the
+light structure of an aeroplane. The aircraft motor, therefore, must be
+balanced to a nicety and must run steadily under the most unfavorable
+conditions.
+
+
+AERIAL MOTORS MUST BE LIGHT
+
+The capacity of light motors designed for aerial work per unit of mass
+is surprising to those not fully conversant with the possibilities that
+a thorough knowledge of proportions of parts and the use of special
+metals developed by the automobile industry make possible. Activity in
+the development of light motors has been more pronounced in France than
+in any other country. Some of these motors have been complicated types
+made light by the skillful proportioning of parts, others are of the
+refined simpler form modified from current automobile practice. There is
+a tendency to depart from the freakish or unconventional construction
+and to adhere more closely to standard forms because it is necessary to
+have the parts of such size that every quality making for reliability,
+efficiency and endurance are incorporated in the design. Aeroplane
+motors range from two cylinders to forms having fourteen and sixteen
+cylinders and the arrangement of these members varies from the
+conventional vertical tandem and opposed placing to the V form or the
+more unusual radial motors having either fixed or rotary cylinders. The
+weight has been reduced so it is possible to obtain a complete power
+plant of the revolving cylinder air-cooled type that will not weigh more
+than three pounds per actual horse-power and in some cases less than
+this.
+
+If we give brief consideration to the requirements of the aviator it
+will be evident that one of the most important is securing maximum power
+with minimum mass, and it is desirable to conserve all of the good
+qualities existing in standard automobile motors. These are certainty of
+operation, good mechanical balance and uniform delivery of
+power--fundamental conditions which must be attained before a power
+plant can be considered practical. There are in addition, secondary
+considerations, none the less desirable, if not absolutely essential.
+These are minimum consumption of fuel and lubricating oil, which is
+really a factor of import, for upon the economy depends the capacity and
+flying radius. As the amount of liquid fuel must be limited the most
+suitable motor will be that which is powerful and at the same time
+economical. Another important feature is to secure accessibility of
+components in order to make easy repair or adjustment of parts possible.
+It is possible to obtain sufficiently light-weight motors without
+radical departure from established practice. Water-cooled power plants
+have been designed that will weigh but four or five pounds per
+horse-power and in these forms we have a practical power plant capable
+of extended operation.
+
+
+FACTORS INFLUENCING POWER NEEDED
+
+Work is performed whenever an object is moved against a resistance, and
+the amount of work performed depends not only on the amount of
+resistance overcome but also upon the amount of time utilized in
+accomplishing a given task. Work is measured in horse-power for
+convenience. It will take one horse-power to move 33,000 pounds one foot
+in one minute or 550 pounds one foot in one second. The same work would
+be done if 330 pounds were moved 100 feet in one minute. It requires a
+definite amount of power to move a vehicle over the ground at a certain
+speed, so it must take power to overcome resistance of an airplane in
+the air. Disregarding the factor of air density, it will take more power
+as the speed increases if the weight or resistance remains constant, or
+more power if the speed remains constant and the resistance increases.
+The airplane is supported by air reaction under the planes or lifting
+surfaces and the value of this reaction depends upon the shape of the
+aerofoil, the amount it is tilted and the speed at which it is drawn
+through the air. The angle of incidence or degree of wing tilt regulates
+the power required to a certain degree as this affects the speed of
+horizontal flight as well as the resistance. Resistance may be of two
+kinds, one that is necessary and the other that it is desirable to
+reduce to the lowest point possible. There is the wing resistance and
+the sum of the resistances of the rest of the machine such as fuselage,
+struts, wires, landing gear, etc. If we assume that a certain airplane
+offered a total resistance of 300 pounds and we wished to drive it
+through the air at a speed of sixty miles per hour, we can find the
+horse-power needed by a very simple computation as follows:
+
+   The product of 300 pounds resistance times speed of
+     88 feet per second times 60 seconds in a minute
+  ----------------------------------------------------- = H.P. needed.
+        divided by 33,000 foot pounds per minute
+                  in one horse-power
+
+The result is the horse-power needed, or
+
+   300 x 88 x 60
+  --------------- = 48 H.P.
+      33,000
+
+Just as it takes more power to climb a hill than it does to run a car on
+the level, it takes more power to climb in the air with an airplane than
+it does to fly on the level. The more rapid the climb, the more power it
+will take. If the resistance remains 300 pounds and it is necessary to
+drive the plane at 90 miles per hour, we merely substitute proper values
+in the above formula and we have
+
+   300 pounds times 132 feet per second times 60
+               seconds in a minute
+  ----------------------------------------------- = 72 H.P.
+       33,000 foot pounds per minute in one
+                  horse-power
+
+The same results can be obtained by dividing the product of the
+resistance in pounds times speed in feet per second by 550, which is the
+foot-pounds of work done in one second to equal one horse-power.
+Naturally, the amount of propeller thrust measured in pounds necessary
+to drive an airplane must be greater than the resistance by a
+substantial margin if the plane is to fly and climb as well. The
+following formulae were given in "The Aeroplane" of London and can be
+used to advantage by those desiring to make computations to ascertain
+power requirements:
+
+[Illustration: Fig. 1.--Diagrams Illustrating Computations for
+Horse-Power Required for Airplane Flight.]
+
+The thrust of the propeller depends on the power of the motor, and on
+the diameter and pitch of the propeller. If the required thrust to a
+certain machine is known, the calculation for the horse-power of the
+motor should be an easy matter.
+
+The required thrust is the sum of three different "resistances." The
+first is the "drift" (dynamical head resistance of the aerofoils), i.e.,
+tan [alpha] x lift (_L_), lift being equal to the total weight of
+machine (_W_) for horizontal flight and [alpha] equal to the angle of
+incidence. Certainly we must take the tan [alpha] at the maximum _K_{y}_
+value for minimum speed, as then the drift is the greatest (Fig. 1, A).
+
+Another method for finding the drift is _D_ = _K_ x _AV_^{2}, when we
+take the drift again so as to be greatest.
+
+The second "resistance" is the total head resistance of the machine, at
+its maximum velocity. And the third is the thrust for climbing. The
+horse-power for climbing can be found out in two different ways. I first
+propose to deal with the method, where we find out the actual
+horse-power wanted for a certain climbing speed to our machine, where
+
+          climbing speed/sec. x _W_
+  H.P. = ---------------------------
+                     550
+
+In this case we know already the horse-power for climbing, and we can
+proceed with our calculation.
+
+With the other method we shall find out the "thrust" in pounds or
+kilograms wanted for climbing and add it to drift and total head
+resistance, and we shall have the total "thrust" of our machine and we
+shall denote it with _T_, while thrust for climbing shall be _T_{c}_.
+
+The following calculation is at our service to find out
+
+                            _V_{c}_ x _W_
+  this thrust for climbing --------------- = H.P.,
+                                 550
+
+                    H.P. x 550
+  thence _V_{c}_ = ------------                                      (1)
+                       _W_
+
+          _T_{c}_ x _V_
+  H.P. = --------------, then from
+               550
+
+                  _T_{c}_ x _V_
+                 --------------- x 550
+                      550                  _T_{c}_ x _V_
+  (1) _V_{c}_ = ----------------------- = ---------------, thence,
+                         _W_                    _W_
+
+           _V_{c}_ x _W_
+  T_{c} = ---------------.
+               _V_
+
+Whether _T_ means drifts, head resistance and thrust for climbing, or
+drift and head resistance only, the following calculation is the same,
+only in the latter case, of course, we must add the horse-power required
+for climbing to the result to obtain the total horse-power.
+
+Now, when we know the total thrust, we shall find the horse-power in the
+following manner:
+
+                           _Pr_2[pi]_R_
+  We know that the H.P. = -------------- in kilograms, or in
+                               75 x 60
+
+                           _Pr_2[pi]_R_
+  English measure, H.P. = -------------- (Fig. 1, B)
+                              33,000
+
+  where _P_ = pressure in klgs. or lbs.
+        _r_ = radius on which _P_ is acting.
+        _R_ = Revolution/min.
+
+                                     _M.R._2[pi]
+  When _P_ x _r_ = _M_, then H.P. = -------------, thence,
+                                        4,500
+
+         H.P. x 4,500     716.2 H.P.
+  _M_ = -------------- = ------------ in meter kilograms,
+           _R_2[pi]          _R_
+
+                              H.P. 33,000     5253.1 H.P.
+  or in English system _M_ = ------------- = ------------- in
+                               _R_2[pi]           _R_
+
+foot pounds.
+
+Now the power on the circumference of the propeller will be reduced by
+its radius, so it will be _M_/_r_ = _p_. A part of _p_ will be used for
+counteracting the air and bearing friction, so that the total power on
+the circumference of the propeller will be (_M_/_r_) x [eta] = _p_ where
+[eta] is the mechanical efficiency of the propeller. Now
+
+       [eta]
+  --------------- = _T_, where [alpha] is taken on the tip of the
+   _tan_ [alpha]
+
+propeller.
+
+I take [alpha] at the tip, but it can be taken, of course, at any point,
+but then in equation _p_ = _M_/_r_, _r_ must be taken only up to this
+point, and not the whole radius; but it is more comfortable to take it
+at the tip, as
+
+                    Pitch
+  _tan_ [alpha] = ---------- (Fig. 1, C).
+                   _r_2[pi]
+
+Now we can write up the equation of the thrust:
+
+   716.2 H.P. [eta]                           5253.1 H.P. [eta]
+  -------------------, or in English measure -------------------
+   _R r tan [alpha]_                          _R r tan [alpha]_
+
+                 _T_ x _R_ x _r tan_ [alpha]
+  thence H.P. = -----------------------------, or in English measure
+                       716.2[eta]
+
+   _T_ x _R_ x _r tan_ [alpha]
+  -----------------------------.
+          5253.1[eta]
+
+The computations and formulae given are of most value to the student
+engineer rather than matters of general interest, but are given so that
+a general idea may be secured of how airplane design influences power
+needed to secure sustained flight. It will be apparent that the
+resistance of an airplane depends upon numerous considerations of design
+which require considerable research in aerodynamics to determine
+accurately. It is obvious that the more resistance there is, the more
+power needed to fly at a given speed. Light monoplanes have been flown
+with as little as 15 horse-power for short distances, but most planes
+now built use engines of 100 horse-power or more. Giant airplanes have
+been constructed having 2,000 horse-power distributed in four power
+units. The amount of power provided for an airplane of given design
+varies widely as many conditions govern this, but it will range from
+approximately one horse-power to each 8 pounds weight in the case of
+very light, fast machines to one horse-power to 15 or 18 pounds of the
+total weight in the case of medium speed machines. The development in
+airplane and power plant design is so rapid, however, that the figures
+given can be considered only in the light of general averages rather
+than being typical of current practice.
+
+
+WHY EXPLOSIVE MOTORS ARE BEST
+
+Internal combustion engines are best for airplanes and all types of
+aircraft for the same reasons that they are universally used as a source
+of power for automobiles. The gasoline engine is the lightest known form
+of prime mover and a more efficient one than a steam engine, especially
+in the small powers used for airplane propulsion. It has been stated
+that by very careful designing a steam plant an engine could be made
+that would be practical for airplane propulsion, but even with the
+latest development it is doubtful if steam power can be utilized in
+aircraft to as good advantage as modern gasoline-engines are. While the
+steam-engine is considered very much simpler than a gas-motor, the
+latter is much more easily mastered by the non-technical aviator and
+certainly requires less attention. A weight of 10 pounds per horse-power
+is possible in a condensing steam plant but this figure is nearly double
+or triple what is easily secured with a gas-motor which may weigh but 5
+pounds per horse-power in the water cooled forms and but 2 or 3 pounds
+in the air-cooled types. The fuel consumption is twice as great in a
+steam-power plant (owing to heat losses) as would be the case in a
+gasoline engine of equal power and much less weight.
+
+The internal-combustion engine has come seemingly like an avalanche of a
+decade; but it has come to stay, to take its well-deserved position
+among the powers for aiding labor. Its ready adaptation to road, aerial
+and marine service has made it a wonder of the age in the development of
+speed not before dreamed of as a possibility; yet in so short a time,
+its power for speed has taken rank on the common road against the
+locomotive on the rail with its century's progress. It has made aerial
+navigation possible and practical, it furnishes power for all marine
+craft from the light canoe to the transatlantic liner. It operates the
+machine tools of the mechanic, tills the soil for the farmer and
+provides healthful recreation for thousands by furnishing an economical
+means of transport by land and sea. It has been a universal mechanical
+education for the masses, and in its present forms represents the great
+refinement and development made possible by the concentration of the
+world's master minds on the problems incidental to internal combustion
+engineering.
+
+
+HISTORICAL
+
+Although the ideal principle of explosive power was conceived some two
+hundred years ago, at which time experiments were made with gunpowder as
+the explosive element, it was not until the last years of the eighteenth
+century that the idea took a patentable shape, and not until about 1826
+(Brown's gas-vacuum engine) that a further progress was made in England
+by condensing the products of combustion by a jet of water, thus
+creating a partial vacuum.
+
+Brown's was probably the first explosive engine that did real work. It
+was clumsy and unwieldy and was soon relegated to its place among the
+failures of previous experiments. No approach to active explosive effect
+in a cylinder was reached in practice, although many ingenious designs
+were described, until about 1838 and the following years. Barnett's
+engine in England was the first attempt to compress the charge before
+exploding. From this time on to about 1860 many patents were issued in
+Europe and a few in the United States for gas-engines, but the progress
+was slow, and its practical introduction for power came with spasmodic
+effect and low efficiency. From 1860 on, practical improvement seems to
+have been made, and the Lenoir motor was produced in France and brought
+to the United States. It failed to meet expectations, and was soon
+followed by further improvements in the Hugon motor in France (1862),
+followed by Beau de Rocha's four-cycle idea, which has been slowly
+developed through a long series of experimental trials by different
+inventors. In the hands of Otto and Langdon a further progress was made,
+and numerous patents were issued in England, France, and Germany, and
+followed up by an increasing interest in the United States, with a few
+patents.
+
+From 1870 improvements seem to have advanced at a steady rate, and
+largely in the valve-gear and precision of governing for variable load.
+The early idea of the necessity of slow combustion was a great drawback
+in the advancement of efficiency, and the suggestion of de Rocha in 1862
+did not take root as a prophetic truth until many failures and years of
+experience had taught the fundamental axiom that rapidity of action in
+both combustion and expansion was the basis of success in explosive
+motors.
+
+With this truth and the demand for small and safe prime movers, the
+manufacture of gas-engines increased in Europe and America at a more
+rapid rate, and improvements in perfecting the details of this cheap and
+efficient prime mover have finally raised it to the dignity of a
+standard motor and a dangerous rival of the steam-engine for small and
+intermediate powers, with a prospect of largely increasing its
+individual units to many hundred, if not to the thousand horse-power in
+a single cylinder. The unit size in a single cylinder has now reached to
+about 700 horse-power and by combining cylinders in the same machine,
+powers of from 1,500 to 2,000 horse-power are now available for large
+power-plants.
+
+
+MAIN TYPES OF INTERNAL-COMBUSTION ENGINES
+
+This form of prime mover has been built in so many different types, all
+of which have operated with some degree of success that the diversity in
+form will not be generally appreciated unless some attempt is made to
+classify the various designs that have received practical application.
+Obviously the same type of engine is not universally applicable, because
+each class of work has individual peculiarities which can best be met by
+an engine designed with the peculiar conditions present in view. The
+following tabular synopsis will enable the reader to judge the extent of
+the development of what is now the most popular prime mover for all
+purposes.
+
+  A.  Internal Combustion (Standard Type)
+        1. Single Acting (Standard Type)
+        2. Double Acting (For Large Power Only)
+        3. Simple (Universal Form)
+        4. Compound (Rarely Used)
+        5. Reciprocating Piston (Standard Type)
+        6. Turbine (Revolving Rotor, not fully developed)
+
+  A1. Two-Stroke Cycle
+        a. Two Port
+        b. Three Port
+        c. Combined Two and Three Port
+        d. Fourth Port Accelerator
+        e. Differential Piston Type
+        f. Distributor Valve System
+
+  A2. Four-Stroke Cycle
+        a. Automatic Inlet Valve
+        b. Mechanical Inlet Valve
+        c. Poppet or Mushroom Valve
+        d. Slide Valve
+             d 1. Sleeve Valve
+             d 2. Reciprocating Ring Valve
+             d 3. Piston Valve
+        e. Rotary Valves
+             e 1. Disc
+             e 2. Cylinder or Barrel
+             e 3. Single Cone
+             e 4. Double Cone
+        f. Two Piston (Balanced Explosion)
+        g. Rotary Cylinder, Fixed Crank (Aerial)
+        h. Fixed Cylinder, Rotary Crank (Standard Type)
+
+  A3. Six-Stroke Cycle
+
+  B.  External Combustion (Practically Obsolete)
+        a. Turbine, Revolving Rotor
+        b. Reciprocating Piston
+
+
+CLASSIFICATION BY CYLINDER ARRANGEMENT
+
+  Single Cylinder
+    a. Vertical
+    b. Horizontal
+    c. Inverted Vertical
+
+  Double Cylinder
+    a. Vertical
+    b. Horizontal (Side by Side)
+    c. Horizontal (Opposed)
+    d. 45 to 90 Degrees V (Angularly Disposed)
+    e. Horizontal Tandem (Double Acting)
+
+  Three Cylinder
+    a. Vertical
+    b. Horizontal
+    c. Rotary (Cylinders Spaced at 120 Degrees)
+    d. Radially Placed (Stationary Cylinders)
+    e. One Vertical, One Each Side at an Angle
+    f. Compound (Two High Pressure, One Low Pressure)
+
+  Four Cylinder
+    a. Vertical
+    b. Horizontal (Side by Side)
+    c. Horizontal (Two Pairs Opposed)
+    d. 45 to 90 Degrees V
+    e. Twin Tandem (Double Acting)
+
+  Five Cylinder
+    a. Vertical (Five Throw Crankshaft)
+    b. Radially Spaced at 72 Degrees (Stationary)
+    c. Radially Placed Above Crankshaft (Stationary)
+    d. Placed Around Rotary Crankcase (72 Degrees Spacing)
+
+  Six Cylinder
+    a. Vertical
+    b. Horizontal (Three Pairs Opposed)
+    c. 45 to 90 Degrees V
+
+  Seven Cylinder
+    a. Equally Spaced (Rotary)
+
+  Eight Cylinder
+    a. Vertical
+    b. Horizontal (Four Pairs Opposed)
+    c. 45 to 90 Degrees V
+
+  Nine Cylinder
+    a. Equally Spaced (Rotary)
+
+  Twelve Cylinder
+    a. Vertical
+    b. Horizontal (Six Pairs Opposed)
+    c. 45 to 90 Degrees V
+
+  Fourteen Cylinder
+    a. Rotary
+
+  Sixteen Cylinder
+    a. 45 to 90 Degrees V
+    b. Horizontal (Eight Pairs Opposed)
+
+  Eighteen Cylinder
+    a. Rotary Cylinder
+
+[Illustration: Fig. 2.--Plate Showing Heavy, Slow Speed Internal
+Combustion Engines Used Only for Stationary Power in Large Installations
+Giving Weight to Horse-Power Ratio.]
+
+[Illustration: Fig. 3.--Various Forms of Internal Combustion Engines
+Showing Decrease in Weight to Horse-Power Ratio with Augmenting Speed of
+Rotation.]
+
+[Illustration: Fig. 4.--Internal Combustion Engine Types of Extremely
+Fine Construction and Refined Design, Showing Great Power Outputs for
+Very Small Weight, a Feature Very Much Desired in Airplane Power
+Plants.]
+
+Of all the types enumerated above engines having less than eight
+cylinders are the most popular in everything but aircraft work. The
+four-cylinder vertical is without doubt the most widely used of all
+types owing to the large number employed as automobile power plants.
+Stationary engines in small and medium powers are invariably of the
+single or double form. Three-cylinder engines are seldom used at the
+present time, except in marine work and in some stationary forms.
+Eight- and twelve-cylinder motors have received but limited application
+and practically always in automobiles, racing motor boats or in aircraft.
+The only example of a fourteen-cylinder motor to be used to any extent
+is incorporated in aeroplane construction. This is also true of the
+sixteen- and eighteen-cylinder forms and of twenty-four-cylinder engines
+now in process of development.
+
+The duty an engine is designed for determines the weight per
+horse-power. High powered engines intended for steady service are always
+of the slow speed type and consequently are of very massive
+construction. Various forms of heavy duty type stationary engines are
+shown at Fig. 2. Some of these engines may weigh as much as 600 pounds
+per horse-power. A further study is possible by consulting data given on
+Figs. 3 and 4. As the crank-shaft speed increases and cylinders are
+multiplied the engines become lighter. While the big stationary power
+plants may run for years without attention, airplane engines require
+rebuilding after about 60 to 80 hours air service for the fixed cylinder
+types and 40 hours or less for the rotary cylinder air-cooled forms.
+There is evidently a decrease in durability and reliability as the
+weight is lessened. These illustrations also permit of obtaining a good
+idea of the variety of forms internal combustion engines are made in.
+
+
+
+
+CHAPTER II
+
+    Operating Principles of Two- and Four-Stroke Engines--Four-cycle
+    Action--Two-cycle Action--Comparing Two- and Four-cycle Types--
+    Theory of Gas and Gasoline Engine--Early Gas-Engine Forms--
+    Isothermal Law--Adiabatic Law--Temperature Computations--Heat
+    and Its Work--Conversion of Heat to Power--Requisites for Best
+    Power Effect.
+
+
+OPERATING PRINCIPLES OF TWO- AND FOUR-STROKE CYCLE ENGINES
+
+Before discussing the construction of the various forms of internal
+combustion engines it may be well to describe the operating cycle of the
+types most generally used. The two-cycle engine is the simplest because
+there are no valves in connection with the cylinder, as the gas is
+introduced into that member and expelled from it through ports cored
+into the cylinder walls. These are covered by the piston at a certain
+portion of its travel and uncovered at other parts of its stroke. In the
+four-cycle engine the explosive gas is admitted to the cylinder through
+a port at the head end closed by a valve, while the exhaust gas is
+expelled through another port controlled in a similar manner. These
+valves are operated by mechanism distinct from the piston.
+
+[Illustration: Fig. 5.--Outlining First Two Strokes of Piston in
+Four-Cycle Engine.]
+
+The action of the four-cycle type may be easily understood if one refers
+to illustrations at Figs. 5 and 6. It is called the "four-stroke engine"
+because the piston must make four strokes in the cylinder for each
+explosion or power impulse obtained. The principle of the gas-engine of
+the internal combustion type is similar to that of a gun, i.e., power is
+obtained by the rapid combustion of some explosive or other quick
+burning substance. The bullet is driven out of the gun barrel by the
+pressure of the gas evolved when the charge of powder is ignited. The
+piston or movable element of the gas-engine is driven from the closed
+or head end to the crank end of the cylinder by a similar expansion of
+gases resulting from combustion. The first operation in firing a gun or
+securing an explosion in the cylinder of the gas-engine is to fill the
+combustion space with combustible material. This is done by a down
+stroke of the piston during which time the inlet valve opens to admit
+the gaseous charge to the cylinder interior. This operation is shown at
+Fig. 5, A. The second operation is to compress this gas which is done by
+an upward stroke of the piston as shown at Fig. 5, B. When the top of
+the compression stroke is reached, the gas is ignited and the piston is
+driven down toward the open end of the cylinder, as indicated at Fig. 6,
+C. The fourth operation or exhaust stroke is performed by the return
+upward movement of the piston as shown at Fig. 6, D during which time
+the exhaust valve is opened to permit the burnt gases to leave the
+cylinder. As soon as the piston reaches the top of its exhaust stroke,
+the energy stored in the fly-wheel rim during the power stroke causes
+that member to continue revolving and as the piston again travels on
+its down stroke the inlet valve opens and admits a charge of fresh gas
+and the cycle of operations is repeated.
+
+[Illustration: Fig. 6.--Outlining Second Two Strokes of Piston in
+Four-Cycle Engine.]
+
+[Illustration: Fig. 7.--Sectional View of L Head Gasoline Engine
+Cylinder Showing Piston Movements During Four-Stroke Cycle.]
+
+The illustrations at Fig. 7 show how the various cycle functions take
+place in an L head type water cooled cylinder engine. The sections at A
+and C are taken through the inlet valve, those at B and D are taken
+through the exhaust valve.
+
+The two-cycle engine works on a different principle, as while only the
+combustion chamber end of the piston is employed to do useful work in
+the four-cycle engine, both upper and lower portions are called upon to
+perform the functions necessary to two-cycle engine operation. Instead
+of the gas being admitted into the cylinder as is the case with the
+four-stroke engine, it is first drawn into the engine base where it
+receives a preliminary compression prior to its transfer to the working
+end of the cylinder. The views at Fig. 8 should indicate clearly the
+operation of the two-port two-cycle engine. At A the piston is seen
+reaching the top of its stroke and the gas above the piston is being
+compressed ready for ignition, while the suction in the engine base
+causes the automatic valve to open and admits mixture from the
+carburetor to the crank case. When the piston reaches the top of its
+stroke, the compressed gas is ignited and the piston is driven down on
+the power stroke, compressing the gas in the engine base.
+
+[Illustration: Fig. 8.--Showing Two-port, Two-cycle Engine Operation.]
+
+When the top of the piston uncovers the exhaust port the flaming gas
+escapes because of its pressure. A downward movement of the piston
+uncovers the inlet port opposite the exhaust and permits the fresh gas
+to bypass through the transfer passage from the engine base to the
+cylinder. The conditions with the intake and exhaust port fully opened
+are clearly shown at Fig. 8, C. The deflector plate on the top of the
+piston directs the entering fresh gas to the top of the cylinder and
+prevents the main portion of the gas stream from flowing out through the
+open exhaust port. On the next upstroke of the piston the gas in the
+cylinder is compressed and the inlet valve opened, as shown at A to
+permit a fresh charge to enter the engine base.
+
+[Illustration: Fig. 9.--Defining Three-port, Two-cycle Engine Action.]
+
+The operating principle of the three-port, two-cycle engine is
+practically the same as that previously described with the exception
+that the gas is admitted to the crank-case through a third port in the
+cylinder wall, which is uncovered by the piston when that member reaches
+the end of its upstroke. The action of the three-port form can be
+readily ascertained by studying the diagrams given at Fig. 9.
+Combination two- and three-port engines have been evolved and other
+modifications made to improve the action.
+
+
+THE TWO-CYCLE AND FOUR-CYCLE TYPES
+
+In the earlier years of explosive-motor progress was evolved the two
+types of motors in regard to the cycles of their operation. The early
+attempts to perfect the two-cycle principle were for many years held in
+abeyance from the pressure of interests in the four-cycle type, until
+its simplicity and power possibilities were demonstrated by Mr. Dugald
+Clerk in England, who gave the principles of the two-cycle motor a broad
+bearing leading to immediate improvements in design, which has made
+further progress in the United States, until at the present time it has
+an equal standard value as a motor-power in some applications as its
+ancient rival the four-cycle or Otto type, as demonstrated by Beau de
+Rocha in 1862.
+
+Thermodynamically, the methods of the two types are equal as far as
+combustion is concerned, and compression may favor in a small degree the
+four-cycle type as well as the purity of the charge. The cylinder volume
+of the two-cycle motor is much smaller per unit of power, and the
+enveloping cylinder surface is therefore greater per unit of volume.
+Hence more heat is carried off by the jacket water during compression,
+and the higher compression available from this tends to increase the
+economy during compression which is lost during expansion.
+
+From the above considerations it may be safely stated that a _lower_
+temperature and higher pressure of charge at the beginning of
+compression is obtained in the two-cycle motor, greater weight of charge
+and greater specific power of higher compression resulting in higher
+thermal efficiency. The smaller cylinder for the same power of the
+two-cycle motor gives less friction surface per impulse than of the
+other type; although the crank-chamber pressure may, in a measure,
+balance the friction of the four-cycle type. Probably the strongest
+points in favor of the two-cycle type are the lighter fly-wheel and the
+absence of valves and valve gear, making this type the most simple in
+construction and the lightest in weight for its developed power. Yet,
+for the larger power units, the four-cycle type will no doubt always
+maintain the standard for efficiency and durability of action.
+
+The distribution of the charge and its degree of mixture with the
+remains of the previous explosion in the clearance space, has been a
+matter of discussion for both types of explosive motors, with doubtful
+results. In Fig. 10, A we illustrate what theory suggests as to the
+distribution of the fresh charge in a two-cycle motor, and in Fig. 10, B
+what is the probable distribution of the mixture when the piston starts
+on its compressive stroke. The arrows show the probable direction of
+flow of the fresh charge and burnt gases at the crucial moment.
+
+[Illustration: Fig. 10.--Diagrams Contrasting Action of Two- and
+Four-Cycle Cylinders on Exhaust and Intake Stroke.]
+
+In Fig. 10, C is shown the complete out-sweep of the products of
+combustion for the full extent of the piston stroke of a four-cycle
+motor, leaving only the volume of the clearance to mix with the new
+charge and at D the manner by which the new charge sweeps by the
+ignition device, keeping it cool and avoiding possibilities of
+pre-ignition by undue heating of the terminals of the sparking device.
+Thus, by enveloping the sparking device with the pure mixture, ignition
+spreads through the charge with its greatest possible velocity, a most
+desirable condition in high-speed motors with side-valve chambers and
+igniters within the valve chamber.
+
+
+THEORY OF THE GAS AND GASOLINE ENGINE
+
+The laws controlling the elements that create a power by their expansion
+by heat due to combustion, when properly understood, become a matter of
+computation in regard to their value as an agent for generating power in
+the various kinds of explosive engines. The method of heating the
+elements of power in explosive engines greatly widens the limits of
+temperature as available in other types of heat-engines. It disposes of
+many of the practical troubles of hot-air, and even of steam-engines, in
+the simplicity and directness of application of the elements of power.
+In the explosive engine the difficulty of conveying heat for producing
+expansive effect by convection is displaced by the generation of the
+required heat within the expansive element and at the instant of its
+useful work. The low conductivity of heat to and from air has been the
+great obstacle in the practical development of the hot-air engine;
+while, on the contrary, it has become the source of economy and
+practicability in the development of the internal-combustion engine.
+
+The action of air, gas, and the vapors of gasoline and petroleum oil,
+whether singly or mixed, is affected by changes of temperature
+practically in nearly the same ratio; but when the elements that produce
+combustion are interchanged in confined spaces, there is a marked
+difference of effect. The oxygen of the air, the hydrogen and carbon of
+a gas, or vapor of gasoline or petroleum oil are the elements that by
+combustion produce heat to expand the nitrogen of the air and the watery
+vapor produced by the union of the oxygen in the air and the hydrogen in
+the gas, as well as also the monoxide and carbonic-acid gas that may be
+formed by the union of the carbon of gas or vapor with part of the
+oxygen of the air. The various mixtures as between air and gas, or air
+and vapor, with the proportion of the products of combustion left in the
+cylinder from a previous combustion, form the elements to be considered
+in estimating the amount of pressure that may be obtained by their
+combustion and expansive force.
+
+
+EARLY GAS ENGINE FORMS
+
+The working process of the explosive motor may be divided into three
+principal types: 1. Motors with charges igniting at constant volume
+without compression, such as the Lenoir, Hugon, and other similar types
+now abandoned as wasteful in fuel and effect. 2. Motors with charges
+igniting at constant pressure with compression, in which a receiver is
+charged by a pump and the gases burned while being admitted to the motor
+cylinder, such as types of the Simon and Brayton engine. 3. Motors with
+charges igniting at constant volume with variable compression, such as
+the later two- and four-cycle motors with compression of the indrawn
+charge; limited in the two-cycle type and variable in the four-cycle
+type with the ratios of the clearance space in the cylinder. This
+principle produces the explosive motor of greatest efficiency.
+
+The phenomena of the brilliant light and its accompanying heat at the
+moment of explosion have been witnessed in the experiments of Dugald
+Clerk in England, the illumination lasting throughout the stroke; but in
+regard to time in a four-cycle engine, the incandescent state exists
+only one-quarter of the running time. Thus the time interval, together
+with the non-conductibility of the gases, makes the phenomena of a
+high-temperature combustion within the comparatively cool walls of a
+cylinder a practical possibility.
+
+
+THE ISOTHERMAL LAW
+
+The natural laws, long since promulgated by Boyle, Gay Lussac, and
+others, on the subject of the expansion and compression of gases by
+force and by heat, and their variable pressures and temperatures when
+confined, are conceded to be practically true and applicable to all
+gases, whether single, mixed, or combined.
+
+The law formulated by Boyle only relates to the compression and
+expansion of gases without a change of temperature, and is stated in
+these words:
+
+_If the temperature of a gas be kept constant, its pressure or elastic
+force will vary inversely as the volume it occupies._
+
+It is expressed in the formula P x V = C, or pressure x volume =
+constant. Hence, C/P = V and C/V = P.
+
+Thus the curve formed by increments of pressure during the expansion or
+compression of a given volume of gas without change of temperature is
+designated as the isothermal curve in which the volume multiplied by the
+pressure is a constant value in expansion, and inversely the pressure
+divided by the volume is a constant value in compressing a gas.
+
+But as compression and expansion of gases require force for their
+accomplishment mechanically, or by the application or abstraction of
+heat chemically, or by convection, a second condition becomes involved,
+which was formulated into a law of thermodynamics by Gay Lussac under
+the following conditions: A given volume of gas under a free piston
+expands by heat and contracts by the loss of heat, its volume causing a
+proportional movement of a free piston equal to 1/273 part of the
+cylinder volume for each degree Centigrade difference in temperature, or
+1/492 part of its volume for each degree Fahrenheit. With a fixed piston
+(constant volume), the pressure is increased or decreased by an increase
+or decrease of heat in the same proportion of 1/273 part of its pressure
+for each degree Centigrade, or 1/492 part of its pressure for each
+degree Fahrenheit change in temperature. This is the natural sequence of
+the law of mechanical equivalent, which is a necessary deduction from
+the principle that nothing in nature can be lost or wasted, for all the
+heat that is imparted to or abstracted from a gaseous body must be
+accounted for, either as heat or its equivalent transformed into some
+other form of energy. In the case of a piston moving in a cylinder by
+the expansive force of heat in a gaseous body, all the heat expended in
+expansion of the gas is turned into work; the balance must be accounted
+for in absorption by the cylinder or radiation.
+
+
+THE ADIABATIC LAW
+
+This theory is equally applicable to the cooling of gases by abstraction
+of heat or by cooling due to expansion by the motion of a piston. The
+denominators of these heat fractions of expansion or contraction
+represent the absolute zero of cold below the freezing-point of water,
+and read -273 deg. C. or -492.66 deg. = -460.66 deg. F. below zero; and
+these are the starting-points of reference in computing the heat expansion
+in gas-engines. According to Boyle's law, called the first law of gases,
+there are but two characteristics of a gas and their variations to be
+considered, _viz_., volume and pressure: while by the law of Gay Lussac,
+called the second law of gases, a third is added, consisting of the
+value of the absolute temperature, counting from absolute zero to the
+temperatures at which the operations take place. This is the _Adiabatic_
+law.
+
+The ratio of the variation of the three conditions--volume, pressure,
+and heat--from the absolute zero temperature has a certain rate, in
+which the volume multiplied by the pressure and the product divided by
+the absolute temperature equals the ratio of expansion for each degree.
+If a volume of air is contained in a cylinder having a piston and fitted
+with an indicator, the piston, if moved to and fro slowly, will
+alternately compress and expand the air, and the indicator pencil will
+trace a line or lines upon the card, which lines register the change of
+pressure and volume occurring in the cylinder. If the piston is
+perfectly free from leakage, and it be supposed that the temperature of
+the air is kept quite constant, then the line so traced is called an
+_Isothermal line_, and the pressure at any point when multiplied by the
+volume is a constant, according to Boyle's law,
+
+  _pv_ = a constant.
+
+If, however, the piston is moved very rapidly, the air will not remain
+at constant temperature, but the temperature will increase because work
+has been done upon the air, and the heat has no time to escape by
+conduction. If no heat whatever is lost by any cause, the line will be
+traced over and over again by the indicator pencil, the cooling by
+expansion doing work precisely equalling the heating by compression.
+This is the line of no transmission of heat, therefore known as
+_Adiabatic_.
+
+[Illustration: Fig. 11.--Diagram Isothermal and Adiabatic Lines.]
+
+The expansion of a gas 1/273 of its volume for every degree Centigrade,
+added to its temperature, is equal to the decimal .00366, the
+coefficient of expansion for Centigrade units. To any given volume of a
+gas, its expansion may be computed by multiplying the coefficient by
+the number of degrees, and by reversing the process the degree of
+acquired heat may be obtained approximately. These methods are not
+strictly in conformity with the absolute mathematical formula, because
+there is a small increase in the increment of expansion of a dry gas,
+and there is also a slight difference in the increment of expansion due
+to moisture in the atmosphere and to the vapor of water formed by the
+union of the hydrogen and oxygen in the combustion chamber of explosive
+engines.
+
+
+TEMPERATURE COMPUTATIONS
+
+The ratio of expansion on the Fahrenheit scale is derived from the
+absolute temperature below the freezing-point of water (32 deg.) to
+correspond with the Centigrade scale; therefore 1/492.66 = .0020297, the
+ratio of expansion from 32 deg. for each degree rise in temperature on
+the Fahrenheit scale. As an example, if the temperature of any volume of
+air or gas at constant volume is raised, say from 60 deg. to 2000 deg.
+F., the increase in temperature will be 1940 deg.. The ratio will be
+1/520.66 = .0019206. Then by the formula:
+
+Ratio x acquired temp. x initial pressure = the gauge pressure; and
+.0019206 x 1940 deg. x 14.7 = 54.77 lbs.
+
+By another formula, a convenient ratio is obtained by (absolute
+pressure)/(absolute temp.) or 14.7/520.66 = .028233; then, using the
+difference of temperature as before, .028233 x 1940 deg. = 54.77 lbs.
+pressure.
+
+By another formula, leaving out a small increment due to specific heat
+at high temperatures:
+
+      Atmospheric pressure x absolute temp. + acquired temp.
+  I. -------------------------------------------------------- =
+                 Absolute temp. + initial temp.
+
+absolute pressure due to the acquired temperature, from which the
+atmospheric pressure is deducted for the gauge pressure. Using the
+foregoing example, we have (14.7 x 460.66 deg. + 2000 deg.)/(460.66 +
+60 deg.) = 69.47 - 14.7 = 54.77, the gauge pressure, 460.66 being the
+absolute temperature for zero Fahrenheit.
+
+For obtaining the volume of expansion of a gas from a given increment of
+heat, we have the approximate formula:
+
+       Volume x absolute temp. + acquired temp.
+  II. ------------------------------------------ =
+            Absolute temp. + initial temp.
+
+heated volume. In applying this formula to the foregoing example, the
+figures become:
+
+        460.66 deg. + 2000 deg.
+  I. x ------------------------- = 4.72604 volumes.
+         460.66 + 60 deg.
+
+From this last term the gauge pressure may be obtained as follows:
+
+III. 4.72604 x 14.7 = 69.47 lbs. absolute - 14.7 lbs. atmospheric
+pressure = 54.77 lbs. gauge pressure; which is the theoretical pressure
+due to heating air in a confined space, or at constant volume from 60
+deg. to 2000 deg. F.
+
+By inversion of the heat formula for absolute pressure we have the
+formula for the acquired heat, derived from combustion at constant
+volume from atmospheric pressure to gauge pressure plus atmospheric
+pressure as derived from Example I., by which the expression
+
+   absolute pressure x absolute temp. + initial temp.
+  ----------------------------------------------------
+               initial absolute pressure
+
+= absolute temperature + temperature of combustion, from which the
+acquired temperature is obtained by subtracting the absolute
+temperature.
+
+Then, for example, (69.47 x 460.66 + 60)/14.7 = 2460.66, and 2460.66 -
+460.66 = 2000 deg., the theoretical heat of combustion. The dropping of
+terminal decimals makes a small decimal difference in the result in the
+different formulas.
+
+
+HEAT AND ITS WORK
+
+By Joule's law of the mechanical equivalent of heat, whenever heat is
+imparted to an elastic body, as air or gas, energy is generated and
+mechanical work produced by the expansion of the air or gas. When the
+heat is imparted by combustion within a cylinder containing a movable
+piston, the mechanical work becomes an amount measurable by the observed
+pressure and movement of the piston. The heat generated by the explosive
+elements and the expansion of the non-combining elements of nitrogen and
+water vapor that may have been injected into the cylinder as moisture in
+the air, and the water vapor formed by the union of the oxygen of the
+air with the hydrogen of the gas, all add to the energy of the work from
+their expansion by the heat of internal combustion. As against this, the
+absorption of heat by the walls of the cylinder, the piston, and
+cylinder-head or clearance walls, becomes a modifying condition in the
+force imparted to the moving piston.
+
+It is found that when any explosive mixture of air and gas or
+hydrocarbon vapor is fired, the pressure falls far short of the pressure
+computed from the theoretical effect of the heat produced, and from
+gauging the expansion of the contents of a cylinder. It is now well
+known that in practice the high efficiency which is promised by
+theoretical calculation is never realized; but it must always be
+remembered that the heat of combustion is the real agent, and that the
+gases and vapors are but the medium for the conversion of inert elements
+of power into the activity of energy by their chemical union. The theory
+of combustion has been the leading stimulus to large expectations with
+inventors and constructors of explosive motors; its entanglement with
+the modifying elements in practice has delayed the best development in
+construction, and as yet no really positive design of best form or
+action seems to have been accomplished, although great progress has been
+made during the past decade in the development of speed, reliability,
+economy, and power output of the individual units of this comparatively
+new power.
+
+One of the most serious difficulties in the practical development of
+pressure, due to the theoretical computations of the pressure value of
+the full heat, is probably caused by imparting the heat of the fresh
+charge to the balance of the previous charge that has been cooled by
+expansion from the maximum pressure to near the atmospheric pressure of
+the exhaust. The retardation in the velocity of combustion of perfectly
+mixed elements is now well known from experimental trials with measured
+quantities; but the principal difficulty in applying these conditions to
+the practical work of an explosive engine where a necessity for a large
+clearance space cannot be obviated, is in the inability to obtain a
+maximum effect from the imperfect mixture and the mingling of the
+products of the last explosion with the new mixture, which produces a
+clouded condition that makes the ignition of the mass irregular or
+chattering, as observed in the expansion lines of indicator cards; but
+this must not be confounded with the reaction of the spring in the
+indicator.
+
+Stratification of the mixture has been claimed as taking place in the
+clearance chamber of the cylinder; but this is not a satisfactory
+explanation in view of the vortical effect of the violent injection of
+the air and gas or vapor mixture. It certainly cannot become a perfect
+mixture in the time of a stroke of a high-speed motor of the two-cycle
+class. In a four-cycle engine, making 1,500 revolutions per minute, the
+injection and compression in any one cylinder take place in one
+twenty-fifth of a second--formerly considered far too short a time for a
+perfect infusion of the elements of combustion but now very easily taken
+care of despite the extremely high speed of numerous aviation and
+automobile power-plants.
+
+TABLE I.--EXPLOSION AT CONSTANT VOLUME IN A CLOSED CHAMBER.
+
+  =====+================================+======+=======+========+=========
+  Dia- |                                | Temp.| Time  |  Ob-   | Com-
+  gram |                                |  of  |  of   | served |puted
+  Curve|        Mixture Injected.       |Injec-|Explo- | Gauge  |Temp.
+  Fig. |                                | tion | sion  |Pressure|Fahr.
+   8.  |                                | Fahr.|Second.| Pounds |
+  -----+--------------------------------+------+-------+--------+---------
+  _a_  |1 volume gas to 14 volumes air. |64 deg| 0.45  |  40.   |1,483 deg.
+  _b_  |1   "     "  "  13    "     "   |51 deg| 0.31  |  51.5  |1,859 deg.
+  _c_  |1   "     "  "  12    "     "   |51 deg| 0.24  |  60.   |2,195 deg.
+  _d_  |1   "     "  "  11    "     "   |51 deg| 0.17  |  61.   |2,228 deg.
+  _e_  |1   "     "  "   9    "     "   |62 deg| 0.08  |  78.   |2,835 deg.
+  _f_  |1   "     "  "   7    "     "   |62 deg| 0.06  |  87.   |3,151 deg.
+  _g_  |1   "     "  "   6    "     "   |51 deg| 0.04  |  90.   |3,257 deg.
+  _h_  |1   "     "  "   5    "     "   |51 deg| 0.055 |  91.   |3,293 deg.
+  _i_  |1   "     "  "   4    "     "   |66 deg| 0.16  |  80.   |2,871 deg.
+  -----+--------------------------------+------+-------+--------+---------
+
+In an examination of the times of explosion and the corresponding
+pressures in both tables, it will be seen that a mixture of 1 part gas
+to 6 parts air is the most effective and will give the highest mean
+pressure in a gas-engine. There is a limit to the relative proportions
+of illuminating gas and air mixture that is explosive, somewhat
+variable, depending upon the proportion of hydrogen in the gas. With
+ordinary coal-gas, 1 of gas to 15 parts of air; and on the lower end of
+the scale, 1 volume of gas to 2 parts air, are non-explosive. With
+gasoline vapor the explosive effect ceases at 1 to 16, and a saturated
+mixture of equal volumes of vapor and air will not explode, while the
+most intense explosive effect is from a mixture of 1 part vapor to 9
+parts air. In the use of gasoline and air mixtures from a carburetor,
+the best effect is from 1 part saturated air to 8 parts free air.
+
+TABLE II.--PROPERTIES AND EXPLOSIVE TEMPERATURE OF A MIXTURE OF ONE PART
+OF ILLUMINATING GAS OF 660 THERMAL UNITS PER CUBIC FOOT WITH VARIOUS
+PROPORTIONS OF AIR WITHOUT MIXTURE OF CHARGE WITH THE PRODUCTS OF A
+PREVIOUS EXPLOSION.
+
+  [A] Proportion, Air to Gas by Volumes.
+  [B] Pounds in One Cubic Foot of Mixture.
+  [C] Specific Heat. Heat Units Required to Raise 1 Lb. 1 Deg.
+      Fahrenheit. Constant Pressure.
+  [D] Specific Heat. Heat Units Required to Raise 1 Lb. 1 Deg.
+      Fahrenheit. Constant Volume.
+  [E] Heat to Raise One Cubic Foot of Mixture 1 Deg. Fahr.
+  [F] Heat Units Evolved by Combustion.
+  [G] Ratio Col. 6/5
+  [H] Usual Combustion Efficiency.
+  [I] Usual Rise of Temperature due to Explosion at Constant Volume.
+
+  =======+========+======+======+========+======+=======+=====+=====
+    [A]  |   [B]  |  [C] |  [D] |   [E]  |  [F] |  [G]  | [H] | [I]
+  -------+--------+------+------+--------+------+-------+-----+-----
+   6 to 1| .074195| .2668| .1913| .014189| 94.28| 6644.6| .465| 3090
+   7 to 1| .075012| .2628| .1882| .014116| 82.  | 5844.4| .518| 3027
+   8 to 1| .075647| .2598| .1858| .014059| 73.33| 5216.1| .543| 2832
+   9 to 1| .076155| .2575| .1846| .014013| 66.  | 4709.9| .56 | 2637
+  10 to 1| .076571| .2555| .1825| .013976| 60.  | 4293. | .575| 2468
+  11 to 1| .076917| .2540| .1813| .013945| 55.  | 3944. | .585| 2307
+  12 to 1| .077211| .2526| .1803| .013922| 50.77| 3646.7| .58 | 2115
+  -------+--------+------+------+--------+------+-------+-----+-----
+
+The weight of a cubic foot of gas and air mixture as given in Col. 2 is
+found by adding the number of volumes of air multiplied by its weight,
+.0807, to one volume of gas of weight .035 pound per cubic foot and
+dividing by the total number of volumes; for example, as in the table, 6
+x .0807 = .5192/7 = .074195 as in the first line, and so on for any
+mixture or for other gases of different specific weight per cubic foot.
+The heat units evolved by combustion of the mixture (Col. 6) are
+obtained by dividing the total heat units in a cubic foot of gas by the
+total proportion of the mixture, 660/7 = 94.28 as in the first line of
+the table. Col. 5 is obtained by multiplying the weight of a cubic foot
+of the mixture in Col. 2 by the specific heat at a constant volume (Col.
+4), Col. 6/Col. 5 = Col. 7 the total heat ratio, of which Col. 8 gives
+the usual combustion efficiency--Col. 7 x Col. 8 gives the absolute rise
+in temperature of a pure mixture, as given in Col. 9.
+
+The many recorded experiments made to solve the discrepancy between the
+theoretical and the actual heat development and resulting pressures in
+the cylinder of an explosive motor, to which much discussion has been
+given as to the possibilities of dissociation and the increased specific
+heat of the elements of combustion and non-combustion, as well, also, of
+absorption and radiation of heat, have as yet furnished no satisfactory
+conclusion as to what really takes place within the cylinder walls.
+There seems to be very little known about dissociation, and somewhat
+vague theories have been advanced to explain the phenomenon. The fact
+is, nevertheless, apparent as shown in the production of water and other
+producer gases by the use of steam in contact with highly incandescent
+fuel. It is known that a maximum explosive mixture of pure gases, as
+hydrogen and oxygen or carbonic oxide and oxygen, suffers a contraction
+of one-third their volume by combustion to their compounds, steam or
+carbonic acid. In the explosive mixtures in the cylinder of a motor,
+however, the combining elements form so small a proportion of the
+contents of the cylinder that the shrinkage of their volume amounts to
+no more than 3 per cent. of the cylinder volume. This by no means
+accounts for the great heat and pressure differences between the
+theoretical and actual effects.
+
+
+CONVERSION OF HEAT TO POWER
+
+The utilization of heat in any heat-engine has long been a theme of
+inquiry and experiment with scientists and engineers, for the purpose of
+obtaining the best practical conditions and construction of heat-engines
+that would represent the highest efficiency or the nearest approach to
+the theoretical value of heat, as measured by empirical laws that have
+been derived from experimental researches relating to its ultimate
+volume. It is well known that the steam-engine returns only from 12 to
+18 per cent. of the power due to the heat generated by the fuel, about
+25 per cent. of the total heat being lost in the chimney, the only use
+of which is to create a draught for the fire; the balance, some 60 per
+cent., is lost in the exhaust and by radiation. The problem of utmost
+utilization of force in steam has nearly reached its limit.
+
+The internal-combustion system of creating power is comparatively new in
+practice, and is but just settling into definite shape by repeated
+trials and modification of details, so as to give somewhat reliable data
+as to what may be expected from the rival of the steam-engine as a prime
+mover. For small powers, the gas, gasoline, and petroleum-oil engines
+are forging ahead at a rapid rate, filling the thousand wants of
+manufacture and business for a power that does not require expensive
+care, that is perfectly safe at all times, that can be used in any place
+in the wide world to which its concentrated fuel can be conveyed, and
+that has eliminated the constant handling of crude fuel and water.
+
+
+REQUISITES FOR BEST POWER EFFECT
+
+The utilization of heat in a gas-engine is mainly due to the manner in
+which the products entering into combustion are distributed in relation
+to the movement of the piston. The investigation of the foremost
+exponent of the theory of the explosive motor was prophetic in
+consideration of the later realization of the best conditions under
+which these motors can be made to meet the requirements of economy and
+practicability. As early as 1862, Beau de Rocha announced, in regard to
+the coming power, that four requisites were the basis of operation for
+economy and best effect. 1. The greatest possible cylinder volume with
+the least possible cooling surface. 2. The greatest possible rapidity of
+expansion. Hence, _high speed_. 3. The greatest possible expansion.
+_Long stroke._ 4. The greatest possible pressure at the commencement of
+expansion. _High compression._
+
+
+
+
+CHAPTER III
+
+    Efficiency of Internal Combustion Engines--Various Measures of
+    Efficiency--Temperatures and Pressures--Factors Governing
+    Economy--Losses in Wall Cooling--Value of Indicator Cards--
+    Compression in Explosive Motors--Factors Limiting Compression--
+    Causes of Heat Losses and Inefficiency--Heat Losses to Cooling
+    Water.
+
+
+EFFICIENCY OF INTERNAL COMBUSTION ENGINES
+
+Efficiencies are worked out through intricate formulas for a variety of
+theoretical and unknown conditions of combustion in the cylinder: ratios
+of clearance and cylinder volume, and the uncertain condition of the
+products of combustion left from the last impulse and the wall
+temperature. But they are of but little value, except as a mathematical
+inquiry as to possibilities. The real commercial efficiency of a gas or
+gasoline-engine depends upon the volume of gas or liquid at some
+assigned cost, required per actual brake horse-power per hour, in which
+an indicator card should show that the mechanical action of the valve
+gear and ignition was as perfect as practicable, and that the ratio of
+clearance, space, and cylinder volume gave a satisfactory terminal
+pressure and compression: _i.e._, the difference between the power
+figured from the indicator card and the brake power being the friction
+loss of the engine.
+
+In four-cycle motors of the compression type, the efficiencies are
+greatly advanced by compression, producing a more complete infusion of
+the mixture of gas or vapor and air, quicker firing, and far greater
+pressure than is possible with the two-cycle type previously described.
+In the practical operation of the gas-engine during the past twenty
+years, the gas-consumption efficiencies per indicated horse-power have
+gradually risen from 17 per cent. to a maximum of 40 per cent. of the
+theoretical heat, and this has been done chiefly through a decreased
+combustion chamber and increased compression--the compression having
+gradually increased in practice from 30 lbs. per square inch to above
+100; but there seems to be a limit to compression, as the efficiency
+ratio decreases with greater increase in compression. It has been shown
+that an ideal efficiency of 33 per cent. for 38 lbs., compression will
+increase to 40 per cent. for 66 lbs., and 43 per cent. for 88 lbs.
+compression. On the other hand, greater compression means greater
+explosive pressure and greater strain on the engine structure, which
+will probably retain in future practice the compression between the
+limits of 40 and 90 lbs. except in super-compression engines intended
+for high altitude work where compression pressures as high as 125 pounds
+have been used.
+
+In experiments made by Dugald Clerk, in England, with a combustion
+chamber equal to 0.6 of the space swept by the piston, with a
+compression of 38 lbs., the consumption of gas was 24 cubic feet per
+indicated horse-power per hour. With 0.4 compression space and 61 lbs.
+compression, the consumption of gas was 20 cubic feet per indicated
+horse-power per hour; and with 0.34 compression space and 87 lbs.
+compression, the consumption of gas fell to 14.8 cubic feet per
+indicated horse-power per hour--the actual efficiencies being
+respectively 17, 21, and 25 per cent. This was with a Crossley
+four-cycle engine.
+
+
+VARIOUS MEASURES OF EFFICIENCY
+
+The efficiencies in regard to power in a heat-engine may be divided
+into four kinds, as follows: I. The first is known as the _maximum
+theoretical efficiency_ of a perfect engine (represented by the
+lines in the indicator diagram). It is expressed by the formula
+(T_{1} - T_{0})/T_{1} and shows the work of a perfect cycle in an engine
+working between the received temperature + absolute temperature (T_{1})
+and the initial atmospheric temperature + absolute temperature (T_{0}).
+II. The second is the _actual heat efficiency_, or the ratio of the heat
+turned into work to the total heat received by the engine. It expresses
+the _indicated horse-power_. III. The third is the ratio between the
+second or _actual heat efficiency_ and the first or _maximum theoretical
+efficiency_ of a perfect cycle. It represents the greatest possible
+utilization of the power of heat in an internal-combustion engine. IV.
+The fourth is the _mechanical efficiency_. This is the ratio between the
+actual horse-power delivered by the engine through a dynamometer or
+measured by a brake (brake horse-power), and the indicated horse-power.
+The difference between the two is the power lost by engine friction. In
+regard to the general heat efficiency of the materials of power in
+explosive engines, we find that with good illuminating gas the practical
+efficiency varies from 25 to 40 per cent.; kerosene-motors, 20 to 30;
+gasoline-motors, 20 to 32; acetylene, 25 to 35; alcohol, 20 to 30 per
+cent. of their heat value. The great variation is no doubt due to
+imperfect mixtures and variable conditions of the old and new charge in
+the cylinder; uncertainty as to leakage and the perfection of
+combustion. In the Diesel motors operating under high pressure, up to
+nearly 500 pounds, an efficiency of 36 per cent. is claimed.
+
+[Illustration: Fig. 12.--Graphic Diagram Showing Approximate Utilization
+of Fuel Burned in Internal-Combustion Engine.]
+
+The graphic diagram at Fig. 12 is of special value as it shows clearly
+how the heat produced by charge combustion is expended in an engine of
+average design.
+
+On general principles the greater difference between the heat of
+combustion and the heat at exhaust is the relative measure of the heat
+turned into work, which represents the degree of efficiency without loss
+during expansion. The mathematical formulas appertaining to the
+computation of the element of heat and its work in an explosive engine
+are in a large measure dependent upon assumed values, as the conditions
+of the heat of combustion are made uncertain by the mixing of the fresh
+charge with the products of a previous combustion, and by absorption,
+radiation, and leakage. The computation of the temperature from the
+observed pressure may be made as before explained, but for
+compression-engines the needed starting-points for computation are very
+uncertain, and can only be approximated from the exact measure and value
+of the elements of combustion in a cylinder charge.
+
+
+TEMPERATURES AND PRESSURES
+
+Owing to the decrease from atmospheric pressure in the indrawing charge
+of the cylinder, caused by valve and frictional obstruction, the
+compression seldom starts above 13 lbs. absolute, especially in
+high-speed engines. Col. 3 in the following table represents the
+approximate absolute compression pressure for the clearance percentage
+and ratio in Cols. 1 and 2, while Col. 4 indicates the gauge pressure
+from the atmospheric line. The temperatures in Col. 5 are due to the
+compression in Col. 3 from an assumed temperature of 560 deg. F. in the
+mixture of the fresh charge of 6 air to 1 gas with the products of
+combustion left in the clearance chamber from the exhaust stroke of a
+medium-speed motor. This temperature is subject to considerable
+variation from the difference in the heat-unit power of the gases and
+vapors used for explosive power, as also of the cylinder-cooling effect.
+In Col. 6 is given the approximate temperatures of explosion for a
+mixture of air 6 to gas 1 of 660 heat units per cubic foot, for the
+relative values of the clearance ratio in Col. 2 at constant volume.
+
+TABLE III.--GAS-ENGINE CLEARANCE RATIOS, APPROXIMATE COMPRESSION,
+TEMPERATURES OF EXPLOSION AND EXPLOSIVE PRESSURES WITH A MIXTURE OF GAS
+OF 660 HEAT UNITS PER CUBIC FOOT AND MIXTURE OF GAS 1 TO 6 OF AIR.
+
+  [A] Clearance Per Cent. of Piston Volume.
+  [B] Ratio (_V_/_V_{c}_) = (_P_ + _C_ Vol.)/Clearance
+  [C] Approximate Compression from 13 Pounds Absolute.
+  [D] Approximate Gauge Pressure.
+  [E] Absolute Temperature of Compression from 560 Deg. Fahrenheit in
+      Cylinder.
+  [F] Absolute Temperature of Explosion. Gas, 1 part; Air, 6 parts.
+  [G] Approximate Explosion Pressure Absolute.
+  [H] Approximate Gauge Pressure.
+  [I] Approximate Temperature of Explosion, Fahrenheit.
+
+  =====+======+======+=====+======+======+=====+=====+=====
+   [A] | [B]  | [C]  | [D] | [E]  | [F]  | [G] | [H] | [I]
+  -----+------+------+-----+------+------+-----+-----+-----
+    1  |  2   |  3   |  4  |  5   |  6   |  7  |  8  |  9
+  -----+------+------+-----+------+------+-----+-----+-----
+       |      | Lbs. |     | Deg. | Deg. |Lbs. |Lbs. | Deg.
+  .50  | 3.   |  57. | 42. | 822. | 2488 | 169 | 144 | 2027
+  .444 | 3.25 |  65. | 50. | 846. | 2568 | 197 | 182 | 2107
+  .40  | 3.50 |  70. | 55. | 868. | 2638 | 212 | 197 | 2177
+  .363 | 3.75 |  77. | 62. | 889. | 2701 | 234 | 219 | 2240
+  .333 | 4.   |  84. | 69. | 910. | 2751 | 254 | 239 | 2290
+  .285 | 4.50 | 102. | 88. | 955. | 2842 | 303 | 288 | 2381
+  .25  | 5.   | 114. | 99. | 983. | 2901 | 336 | 321 | 2440
+  -----+------+------+-----+------+------+-----+-----+-----
+
+
+FACTORS GOVERNING ECONOMY
+
+In view of the experiments in this direction, it clearly shows that in
+practical work, to obtain the greatest economy per effective brake
+horse-power, it is necessary: 1st. To transform the heat into work with
+the greatest rapidity mechanically allowable. This means high piston
+speed. 2d. To have high initial compression. 3d. To reduce the duration
+of contact between the hot gases and the cylinder walls to the smallest
+amount possible; which means short stroke and quick speed, with a
+spherical cylinder head. 4th. To adjust the temperature of the jacket
+water to obtain the most economical output of actual power. This means
+water-tanks or water-coils, with air-cooling surfaces suitable and
+adjustable to the most economical requirement of the engine, which by
+late trials requires the jacket water to be discharged at about 200 deg.
+F. 5th. To reduce the wall surface of the clearance space or combustion
+chamber to the smallest possible area, in proportion to its required
+volume. This lessens the loss of the heat of combustion by exposure to a
+large surface, and allows of a higher mean wall temperature to
+facilitate the heat of compression.
+
+
+LOSSES IN WALL COOLING
+
+In an experimental investigation of the efficiency of a gas-engine under
+variable piston speeds made in France, it was found that the useful
+effect increases with the velocity of the piston--that is, with the rate
+of expansion of the burning gases with mixtures of uniform volumes: so
+that the variations of time of complete combustion at constant pressure,
+and the variations due to speed, in a way compensate in their
+efficiencies. The dilute mixture, being slow burning, will have its time
+and pressure quickened by increasing the speed.
+
+Careful trials give unmistakable evidence that the useful effect
+increases with the velocity of the piston--that is, with the rate of
+expansion of the burning gases. The time necessary for the explosion to
+become complete and to attain its maximum pressure depends not only on
+the composition of the mixture, but also upon the rate of expansion.
+This has been verified in experiments with a high-speed motor, at speeds
+from 500 to 2,000 revolutions per minute, or piston speeds of from 16 to
+64 feet per second. The increased speed of combustion due to increased
+piston speed is a matter of great importance to builders of gas-engines,
+as well as to the users, as indicating the mechanical direction of
+improvements to lessen the wearing strain due to high speed and to
+lighten the vibrating parts with increased strength, in order that the
+balancing of high-speed engines may be accomplished with the least
+weight.
+
+From many experiments made in Europe and in the United States, it has
+been conclusively proved that excessive cylinder cooling by the
+water-jacket results in a marked loss of efficiency. In a series of
+experiments with a simplex engine in France, it was found that a saving
+of 7 per cent. in gas consumption per brake horse-power was made by
+raising the temperature of the jacket water from 141 deg. to 165 deg. F.
+A still greater saving was made in a trial with an Otto engine by raising
+the temperature of the jacket water from 61 deg. to 140 deg. F.--it being
+9.5 per cent. less gas per brake horse-power.
+
+It has been stated that volumes of similar cylinders increase as the
+cube of their diameters, while the surface of their cold walls varies as
+the square of their diameters; so that for large cylinders the ratio of
+surface to volume is less than for small ones. This points to greater
+economy in the larger engines. The study of many experiments goes to
+prove that combustion takes place gradually in the gas-engine cylinder,
+and that the rate of increase of pressure or rapidity of firing is
+controlled by dilution and compression of the mixture, as well as by the
+rate of expansion or piston speed. The rate of combustion also depends
+on the size and shape of the explosion chamber, and is increased by the
+mechanical agitation of the mixture during combustion, and still more by
+the mode of firing.
+
+
+VALUE OF INDICATOR CARDS
+
+[Illustration: Fig. 13.--Otto Four-Cycle Card.]
+
+To the uninitiated, indicator cards are considerable of a mystery; to
+those capable of reading them they form an index relative to the action
+of any engine. An indicator card, such as shown at Fig. 13, is merely a
+graphical representation of the various pressures existing in the
+cylinder for different positions of the piston. The length is to some
+scale that represents the stroke of the piston. During the intake
+stroke, the pressure falls below the atmospheric line. During
+compression, the curve gradually becomes higher owing to increasing
+pressure as the volume is reduced. After ignition the pressure line
+moves upward almost straight, then as the piston goes down on the
+explosion stroke, the pressure falls gradually to the point of exhaust
+valve, opening when the sudden release of the imprisoned gas causes a
+reduction in pressure to nearly atmospheric. An indicator card, or a
+series of them, will always show by its lines the normal or defective
+condition of the inlet valve and passages; the actual line of
+compression; the firing moment; the pressure of explosion; the velocity
+of combustion; the normal or defective line of expansion, as measured by
+the adiabatic curve, and the normal or defective operation of the
+exhaust valve, exhaust passages, and exhaust pipe. In fact, all the
+cycles of an explosive motor may be made a practical study from a close
+investigation of the lines of an indicator card.
+
+[Illustration: Fig. 14.--Diesel Motor Card.]
+
+A most unique card is that of the Diesel motor (Fig. 14), which involves
+a distinct principle in the design and operation of internal-combustion
+motors, in that instead of taking a mixed charge for instantaneous
+explosion, its charge primarily is of air and its compression to a
+pressure at which a temperature is attained above the igniting point of
+the fuel, then injecting the fuel under a still higher pressure by which
+spontaneous combustion takes place gradually with increasing volume over
+the compression for part of the stroke or until the fuel charge is
+consumed. The motor thus operating between the pressures of 500 and 35
+lbs. per square inch, with a clearance of about 7 per cent., has given
+an efficiency of 36 per cent. of the total heat value of kerosene oil.
+
+
+COMPRESSION IN EXPLOSIVE MOTORS
+
+That the compression in a gas, gasoline, or oil-engine has a direct
+relation to the power obtained, has been long known to experienced
+builders, having been suggested by M. Beau de Rocha, in 1862, and
+afterward brought into practical use in the four-cycle or Otto type
+about 1880. The degree of compression has had a growth from zero, in the
+early engines, to the highest available due to the varying ignition
+temperatures of the different gases and vapors used for explosive fuel,
+in order to avoid premature explosion from the heat of compression. Much
+of the increased power for equal-cylinder capacity is due to compression
+of the charge from the fact that the most powerful explosion of gases,
+or of any form of explosive material, takes place when the particles are
+in the closest contact or cohesion with one another, less energy in this
+form being consumed by the ingredients themselves to bring about their
+chemical combination, and consequently more energy is given out in
+useful or available work. This is best shown by the ignition of
+gunpowder, which, when ignited in the open air, burns rapidly, but
+without explosion, an explosion only taking place if the powder be
+confined or compressed into a small space.
+
+[Illustration: Fig. 15.--Diagram of Heat in the Gas Engine Cylinder.]
+
+In a gas or gasoline-motor with a small clearance or compression
+space--with high compression--the surface with which the burning
+gases come into contact is much smaller in comparison with the
+compression space in a low-compression motor. Another advantage of a
+high-compression motor is that on account of the smaller clearance
+of combustion space less cooling water is required than with a
+low-compression motor, as the temperature, and consequently the
+pressure, falls more rapidly. The loss of heat through the water-jacket
+is thus less in the case of a high-compression than in that of a
+low-compression motor. In the non-compression type of motor the best
+results were obtained with a charge of 16 to 18 parts of gas and 100
+parts of air, while in the compression type the best results are
+obtained with an explosive mixture of 7 to 10 parts of gas and 100 parts
+of air, thus showing that by the utilization of compression a weaker
+charge with a greater thermal efficiency is permissible.
+
+It has been found that the explosive pressure resulting from the
+ignition of the charge of gas or gasoline-vapor and air in the
+gas-engine cylinder is about 4-1/2 times the pressure prior to ignition.
+The difficulty about getting high compression is that if the pressure is
+too high the charge is likely to ignite prematurely, as compression
+always results in increased temperature. The cylinder may become too
+hot, a deposit of carbon, a projecting electrode or plug body in the
+cylinder may become incandescent and ignite the charge which has been
+excessively heated by the high compression and mixture of the hot gases
+of the previous explosion.
+
+
+FACTORS LIMITING COMPRESSION
+
+With gasoline-vapor and air the compression should not be raised above
+about 90 to 95 pounds to the square inch, many manufacturers not going
+above 65 or 70 pounds. For natural gas the compression pressure may
+easily be raised to from 85 to 100 pounds per square inch. For gases of
+low calorific value, such as blast-furnace or producer-gas, the
+compression may be increased to from 140 to 190 pounds. In fact the
+ability to raise the compression to a high point with these gases is one
+of the principal reasons for their successful adoption for gas-engine
+use. In kerosene injection engines the compression of 250 pounds per
+square inch has been used with marked economy. Many troubles in regard
+to loss of power and increase of fuel have occurred and will no doubt
+continue, owing to the wear of valves, piston, and cylinder, which
+produces a loss in compression and explosive pressure and a waste of
+fuel by leakage. Faulty adjustment of valve movement is also a cause of
+loss of power; which may be from tardy closing of the inlet-valve or a
+too early opening of the exhaust-valve.
+
+The explosive pressure varies to a considerable amount in proportion to
+the compression pressure by the difference in fuel value and the
+proportions of air mixtures, so that for good illuminating gas the
+explosive pressure may be from 2.5 to 4 times the compression pressure.
+For natural gas 3 to 4.5, for gasoline 3 to 5, for producer-gas 2 to 3,
+and for kerosene by injection 3 to 6.
+
+The compression temperatures, although well known and easily computed
+from a known normal temperature of the explosive mixture, are subject to
+the effect of the uncertain temperature of the gases of the previous
+explosion remaining in the cylinder, the temperature of its walls, and
+the relative volume of the charge, whether full or scant; which are
+terms too variable to make any computations reliable or available.
+
+For the theoretical compression temperatures from a known normal
+temperature, we append a table of the rise in temperature for the
+compression pressures in the following table:
+
+TABLE IV.--COMPRESSION TEMPERATURES FROM A NORMAL TEMPERATURE OF 60
+DEGREES FAHRENHEIT.
+
+  ===============================+==============================
+  100 lbs. gauge        484 deg. | 60 lbs. gauge        373 deg.
+   90 lbs. gauge        459 deg. | 50 lbs. gauge        339 deg.
+   80 lbs. gauge        433 deg. | 40 lbs. gauge        301 deg.
+   70 lbs. gauge        404 deg. | 30 lbs. gauge        258 deg.
+  -------------------------------+------------------------------
+
+
+CHART FOR DETERMINING COMPRESSION PRESSURES
+
+A very useful chart (Fig. 16) for determining compression pressures in
+gasoline-engine cylinders for various ratios of compression space to
+total cylinder volume is given by P. S. Tice, and described in the
+Chilton Automobile Directory by the originator as follows:
+
+[Illustration: Fig. 16.--Chart Showing Relation Between Compression
+Volume and Pressure.]
+
+It is many times desirable to have at hand a convenient means for at
+once determining with accuracy what the compression pressure will be in
+a gasoline-engine cylinder, the relationship between the volume of the
+compression space and the total cylinder volume or that swept by the
+piston being known. The curve at Fig. 16 is offered as such a means. It
+is based on empirical data gathered from upward of two dozen modern
+automobile engines and represents what may be taken to be the results as
+found in practice. It is usual for the designer to find compression
+pressure values, knowing the volumes from the equation
+
+  P_{2} = P_{1} (V_{1}/V_{2})^{1.4}                                  1
+
+which is for adiabatic compression of air. Equation (1) is right enough
+in general form but gives results which are entirely too high, as
+almost all designers know from experience. The trouble lies in the
+interchange of heat between the compressed gases and the cylinder walls,
+in the diminution of the exponent (1.4 in the above) due to the lesser
+ratio of specific heat of gasoline vapor and in the transfer of heat
+from the gases which are being compressed to whatever fuel may enter the
+cylinder in an unvaporized condition. Also, there is always some piston
+leakage, and, if the form of the equation (1) is to be retained, this
+also tends to lower the value of the exponent. From experience with many
+engines, it appears that compression reaches its highest value in the
+cylinder for but a short range of motor speeds, usually during the
+mid-range. Also, it appears that, at those speeds at which compression
+shows its highest values, the initial pressure at the start of the
+compression stroke is from .5 to .9 lb. below atmospheric. Taking this
+latter loss value, which shows more often than those of lesser value,
+the compression is seen to start from an initial pressure of 13.9 lbs.
+per sq. in. absolute.
+
+Also, experiment shows that if the exponent be given the value 1.26,
+instead of 1.4, the equation will embrace all heat losses in the
+compressed gas, and compensate for the changed ratio of specific heats
+for the mixture and also for all piston leakage, in the average engine
+with rings in good condition and tight. In the light of the foregoing,
+and in view of results obtained from its use, the above curve is
+offered--values of P_{2} being found from the equation
+
+  P_{2} = 13.8 (V_{1}/V_{2})^{1.26}
+
+In using this curve it must be remembered that pressures are absolute.
+Thus: suppose it is desired to know the volumetric relationships of the
+cylinder for a compression pressure of 75 lbs. gauge. Add atmospheric
+pressure to the desired gauge pressure 14.7 + 75 = 89.7 lbs. absolute.
+Locate this pressure on the scale of ordinates and follow horizontally
+across to the curve and then vertically downward to the scale of
+abscissas, where the ratio of the combustion chamber volume to the total
+cylinder volume is given, which latter is equal to the sum of the
+combustion chamber volume and that of the piston sweep. In the above
+case it is found that the combustion space for a compression pressure of
+75 lbs. gauge will be .225 of the total cylinder volume, or .225 / .775
+= .2905 of the piston sweep volume. Conversely, knowing the volumetric
+ratios, compression pressure can be read directly by proceeding from the
+scale of abscissas vertically to the curve and thence horizontally to
+the scale of ordinates.
+
+
+CAUSES OF HEAT LOSS AND INEFFICIENCY IN EXPLOSIVE MOTORS
+
+The difference realized in the practical operation of an internal
+combustion heat engine from the computed effect derived from the values
+of the explosive elements is probably the most serious difficulty that
+engineers have encountered in their endeavors to arrive at a rational
+conclusion as to where the losses were located, and the ways and means
+of design that would eliminate the causes of loss and raise the
+efficiency step by step to a reasonable percentage of the total
+efficiency of a perfect cycle.
+
+An authority on the relative condition of the chemical elements under
+combustion in closed cylinders attributes the variation of temperature
+shown in the fall of the expansion curve, and the suppression or
+retarded evolution of heat, entirely to the cooling action of the
+cylinder walls, and to this nearly all the phenomena hitherto obscure in
+the cylinder of a gas-engine. Others attribute the great difference
+between the theoretical temperature of combustion and the actual
+temperature realized in the practical operation of the gas-engine, a
+loss of more than one-half of the total heat energy of the combustibles,
+partly to the dissociation of the elements of combustion at extremely
+high temperatures and their reassociation by expansion in the cylinder,
+to account for the supposed continued combustion and extra adiabatic
+curve of the expansion line on the indicator card.
+
+[Illustration: Fig. 17.--The Thompson Indicator, an Instrument for
+Determining Compressions and Explosion Pressure Values and Recording
+Them on Chart.]
+
+The loss of heat to the walls of the cylinder, piston, and clearance
+space, as regards the proportion of wall surface to the volume, has
+gradually brought this point to its smallest ratio in the concave
+piston-head and globular cylinder-head, with the smallest possible space
+in the inlet and exhaust passage. The wall surface of a cylindrical
+clearance space or combustion chamber of one-half its unit diameter in
+length is equal to 3.1416 square units, its volume but 0.3927 of a cubic
+unit; while the same wall surface in a spherical form has a volume of
+0.5236 of a cubic unit. It will be readily seen that the volume is
+increased 33-1/3 per cent. in a spherical over a cylindrical form for
+equal wall surfaces at the moment of explosion, when it is desirable
+that the greatest amount of heat is generated, and carrying with it the
+greatest possible pressure from which the expansion takes place by the
+movement of the piston.
+
+[Illustration: Fig. 18.--Spherical Combustion Chamber.]
+
+[Illustration: Fig. 19.--Enlarged Combustion Chamber.]
+
+The spherical form cannot continue during the stroke for mechanical
+reasons; therefore some proportion of piston stroke of cylinder volume
+must be found to correspond with a spherical form of the combustion
+chamber to produce the least loss of heat through the walls during the
+combustion and expansion part of the stroke. This idea is illustrated in
+Figs. 18 and 19, showing how the relative volumes of cylinder stroke and
+combustion chamber may be varied to suit the requirements due to the
+quality of the elements of combustion.
+
+Although the concave piston-head shows economy in regard to the relation
+of the clearance volume to the wall area at the moment of explosive
+combustion, it may be clearly seen that its concavity increases its
+surface area and its capacity for absorbing heat, for which there is no
+provision for cooling the piston, save its contact with the walls of the
+cylinder and the slight air cooling of its back by its reciprocal
+motion. For this reason the concave piston-head has not been generally
+adopted and the concave cylinder-head, as shown in Fig. 19, with a
+flat piston-head is the latest and best practice in airplane engine
+construction.
+
+[Illustration: Fig. 20.--Mercedes Aviation Engine Cylinder Section
+Showing Approximately Spherical Combustion Chamber and Concave Piston
+Top.]
+
+The practical application of the principle just outlined to one of the
+most efficient airplane motors ever designed, the Mercedes, is clearly
+outlined at Fig. 20.
+
+
+HEAT LOSSES TO COOLING WATER
+
+The mean temperature of the wall surface of the combustion chamber and
+cylinder, as indicated by the temperatures of the circulating water, has
+been found to be an important item in the economy of the gas-engine.
+Dugald Clerk, in England, a high authority in practical work with the
+gas-engine, found that 10 per cent. of the gas for a stated amount of
+power was saved by using water at a temperature in which the ejected
+water from the cylinder-jacket was near the boiling-point, and ventures
+the opinion that a still higher temperature for the circulating water
+may be used as a source of economy. This could be made practical in the
+case of aviation engines by adjusting the air-cooling surface of the
+radiator so as to maintain the inlet water at just below the boiling
+point, and by the rapid circulation induced by the pump pressure, to
+return the water from the cylinder-jacket a few degrees above the
+boiling point. The thermal displacement systems of cooling employed in
+automobiles are working under more favorable temperature conditions than
+those engines in which cooling is more energetic.
+
+For a given amount of heat taken from the cylinder by the largest volume
+of circulating water, the difference in temperature between inlet and
+outlet of the water-jacket should be the least possible, and this
+condition of the water circulation gives a more even temperature to all
+parts of the cylinder; while, on the contrary, a cold-water supply, say
+at 60 deg. F., so slow as to allow the ejected water to flow off at a
+temperature near the boiling-point, must make a great difference in
+temperature between the bottom and top of the cylinder, with a loss in
+economy in gas and other fuels, as well as in water, if it is obtained
+by measurement.
+
+From the foregoing considerations of losses and inefficiencies, we find
+that the practice in motor design and construction has not yet reached
+the desired perfection in its cycular operation. Step by step
+improvements have been made with many changes in design though many have
+been without merit as an improvement, farther than to gratify the
+longings of designers for something different from the other thing, and
+to establish a special construction of their own. These efforts may in
+time produce a motor of normal or standard design for each kind of fuel
+that will give the highest possible efficiency for all conditions of
+service.
+
+
+
+
+CHAPTER IV
+
+    Engine Parts and Functions--Why Multiple Cylinder Engines Are
+    Best--Describing Sequence of Operations--Simple Engines--Four
+    and Six Cylinder Vertical Tandem Engines--Eight and Twelve
+    Cylinder V Engines--Radial Cylinder Arrangement--Rotary Cylinder
+    Forms.
+
+
+ENGINE PARTS AND FUNCTIONS
+
+The principal elements of a gas engine are not difficult to understand
+and their functions are easily defined. In place of the barrel of the
+gun one has a smoothly machined cylinder in which a small cylindrical or
+barrel-shaped element fitting the bore closely may be likened to a
+bullet or cannon ball. It differs in this important respect, however, as
+while the shot is discharged from the mouth of the cannon the piston
+member sliding inside of the main cylinder cannot leave it, as its
+movements back and forth from the open to the closed end and back again
+are limited by simple mechanical connection or linkage which comprises
+crank and connection rod. It is by this means that the reciprocating
+movement of the piston is transformed into a rotary motion of the
+crank-shaft.
+
+The fly-wheel is a heavy member attached to the crank-shaft of an
+automobile engine which has energy stored in its rim as the member
+revolves, and the momentum of this revolving mass tends to equalize the
+intermittent pushes on the piston head produced by the explosion of the
+gas in the cylinder. In aviation engines, the weight of the propeller or
+that of rotating cylinders themselves performs the duty of a fly-wheel,
+so no separate member is needed. If some explosive is placed in the
+chamber formed by the piston and closed end of the cylinder and
+exploded, the piston would be the only part that would yield to the
+pressure which would produce a downward movement. As this is forced down
+the crank-shaft is turned by the connecting rod, and as this part is
+hinged at both ends it is free to oscillate as the crank turns, and thus
+the piston may slide back and forth while the crank-shaft is rotating or
+describing a curvilinear path.
+
+[Illustration: Fig. 21.--Side Sectional View of Typical Airplane Engine,
+Showing Parts and Their Relation to Each Other. This Engine is an
+Aeromarine Design and Utilizes a Distinctive Concentric Valve
+Construction.]
+
+In addition to the simple elements described it is evident that a
+gasoline engine must have other parts. The most important of these are
+the valves, of which there are generally two to each cylinder. One
+closes the passage connecting to the gas supply and opens during one
+stroke of the piston in order to let the explosive gas into the
+combustion chamber. The other member, or exhaust valve, serves as a
+cover for the opening through which the burned gases can leave the
+cylinder after their work is done. The spark plug is a simple device
+which may be compared to the fuse or percussion cap of the cannon. It
+permits one to produce an electric spark in the cylinder when the piston
+is at the best point to utilize the pressure which obtains when the
+compressed gas is fired. The valves are open one at a time, the inlet
+valve being lifted from its seat while the cylinder is filling and the
+exhaust valve is opened when the cylinder is being cleared. They are
+normally kept seated by means of compression springs. In the simple
+motor shown at Fig. 5, the exhaust valve is operated by means of a
+pivoted bell crank rocked by a cam which turns at half the speed of the
+crank-shaft. The inlet valve operates automatically, as will be
+explained in proper sequence.
+
+In order to obtain a perfectly tight combustion chamber, both intake and
+exhaust valves are closed before the gas is ignited, because all of the
+pressure produced by the exploding gas is to be directed against the top
+of the movable piston. When the piston reaches the bottom of its power
+stroke, the exhaust valve is lifted by means of the bell crank which is
+rocked because of the point or lift on the cam. The cam-shaft is driven
+by positive gearing and revolves at half the engine speed. The exhaust
+valve remains open during the whole of the return stroke of the piston,
+and as this member moves toward the closed end of the cylinder it
+forces out burned gases ahead of it, through the passage controlled by
+the exhaust valve. The cam-shaft is revolved at half the engine speed
+because the exhaust valve is raised from its seat during only one stroke
+out of four, or only once every two revolutions. Obviously, if the cam
+was turned at the same speed as the crank-shaft it would remain open
+once every revolution, whereas the burned gases are expelled from the
+individual cylinders only once in two turns of the crank-shaft.
+
+
+WHY MULTIPLE CYLINDER FORMS ARE BEST
+
+Owing to the vibration which obtains from the heavy explosion in the
+large single-cylinder engines used for stationary power other forms were
+evolved in which the cylinder was smaller and power obtained by running
+the engine faster, but these are suitable only for very low powers.
+
+When a single-cylinder engine is employed a very heavy fly-wheel is
+needed to carry the moving parts through idle strokes necessary to
+obtain a power impulse. For this reason automobile and aircraft
+designers must use more than one cylinder, and the tendency is to
+produce power by frequently occurring light impulses rather than
+by a smaller number of explosions having greater force. When a
+single-cylinder motor is employed the construction is heavier than is
+needed with a multiple-cylinder form. Using two or more cylinders
+conduces to steady power generation and a lessening of vibration. Most
+modern motor cars employ four-cylinder engines because a power impulse
+may be secured twice every revolution of the crank-shaft, or a total of
+four power strokes during two revolutions. The parts are so arranged
+that while the charge of gas in one cylinder is exploding, those which
+come next in firing order are compressing, discharging the inert gases
+and drawing in a fresh charge respectively. When the power stroke is
+completed in one cylinder, the piston in that member in which a charge
+of gas has just been compressed has reached the top of its stroke and
+when the gas is exploded the piston is reciprocated and keeps the
+crank-shaft turning. When a multiple-cylinder engine is used the
+fly-wheel can be made much lighter than that of the simpler form and
+eliminated altogether in some designs. In fact, many modern
+multiple-cylinder engines developing 300 horse-power weigh less than the
+early single- and double-cylinder forms which developed but one-tenth or
+one-twentieth that amount of energy.
+
+
+DESCRIBING SEQUENCE OF OPERATIONS
+
+Referring to Fig. 22, A, the sequence of operation in a single-cylinder
+motor can be easily understood. Assuming that the crank-shaft is turning
+in the direction of the arrow, it will be seen that the intake stroke
+comes first, then the compression, which is followed by the power
+impulse, and lastly the exhaust stroke. If two cylinders are used, it is
+possible to balance the explosions in such a way that one will occur
+each revolution. This is true with either one of two forms of four-cycle
+motors. At B, a two-cylinder vertical engine using a crank-shaft in
+which the crank-pins are on the same plane is shown. The two pistons
+move up and down simultaneously. Referring to the diagram describing the
+strokes, and assuming that the outer circle represents the cycle of
+operations in one cylinder while the inner circle represents the
+sequence of events in the other cylinder, while cylinder No. 1 is taking
+in a fresh charge of gas, cylinder No. 2 is exploding. When cylinder No.
+1 is compressing, cylinder No. 2 is exhausting. During the time that the
+charge in cylinder No. 1 is exploded, cylinder No. 2 is being filled
+with fresh gas. While the exhaust gases are being discharged from
+cylinder No. 1, cylinder No. 2 is compressing the gas previously taken.
+
+[Illustration: Fig. 22.--Diagrams Illustrating Sequence of Cycles in
+One- and Two-Cylinder Engines Showing More Uniform Turning Effort on
+Crank-Shaft with Two-Cylinder Motors.]
+
+The same condition obtains when the crank-pins are arranged at one
+hundred and eighty degrees and the cylinders are opposed, as shown at C.
+The reason that the two-cylinder opposed motor is more popular than
+that having two vertical cylinders is that it is difficult to balance
+the construction shown at B, so that the vibration will not be
+excessive. The two-cylinder opposed motor has much less vibration than
+the other form, and as the explosions occur evenly and the motor is a
+simple one to construct, it has been very popular in the past on light
+cars and has received limited application on some early, light
+airplanes.
+
+To demonstrate very clearly the advantages of multiple-cylinder engines
+the diagrams at Fig. 23 have been prepared. At A, a three-cylinder
+motor, having crank-pins at one hundred and twenty degrees, which means
+that they are spaced at thirds of the circle, we have a form of
+construction that gives a more even turning than that possible with a
+two-cylinder engine. Instead of one explosion per revolution of the
+crank-shaft, one will obtain three explosions in two revolutions. The
+manner in which the explosion strokes occur and the manner they overlap
+strokes in the other cylinder is shown at A. Assuming that the cylinders
+fire in the following order, first No. 1, then No. 2, and last No. 3, we
+will see that while cylinder No. 1, represented by the outer circle, is
+on the power stroke, cylinder No. 3 has completed the last two-thirds of
+its exhaust stroke and has started on its intake stroke. Cylinder No. 2,
+represented by the middle circle, during this same period has completed
+its intake stroke and two-thirds of its compression stroke. A study of
+the diagram will show that there is an appreciable lapse of time between
+each explosion.
+
+Three-cylinder engines are not used on aircraft at the present time,
+though Bleriot's flight across the British Channel was made with a
+three-cylinder Anzani motor. It was not a conventional form, however.
+The three-cylinder engine is practically obsolete at this time for any
+purpose except "penguins" or school machines that are incapable of
+flight and which are used in some French training schools for aviators.
+
+[Illustration: Fig. 23.--Diagrams Demonstrating Clearly Advantages which
+Obtain when Multiple-Cylinder Motors are Used as Power Plants.]
+
+
+FOUR- AND SIX-CYLINDER ENGINES
+
+In the four-cylinder engine operation which is shown at Fig. 23, B, it
+will be seen that the power strokes follow each other without loss of
+time, and one cylinder begins to fire and the piston moves down just as
+soon as the member ahead of it has completed its power stroke. In a
+four-cylinder motor, the crank-pins are placed at one hundred and eighty
+degrees, or on the halves of the crank circle. The crank-pins for
+cylinders No. 1 and No. 4 are on the same plane, while those for
+cylinders No. 2 and No. 3 also move in unison. The diagram describing
+sequence of operations in each cylinder is based on a firing order of
+one, two, four, three. The outer circle, as in previous instances,
+represents the cycle of operations in cylinder one. The next one toward
+the center, cylinder No. 2, the third circle represents the sequence of
+events in cylinder No. 3, while the inner circle outlines the strokes in
+cylinder four. The various cylinders are working as follows:
+
+      1.           2.           3.           4.
+
+  Explosion    Compression  Exhaust      Intake
+  Exhaust      Explosion    Intake       Compression
+  Intake       Exhaust      Compression  Explosion
+  Compression  Intake       Explosion    Exhaust
+
+It will be obvious that regardless of the method of construction, or the
+number of cylinders employed, exactly the same number of parts must be
+used in each cylinder assembly and one can conveniently compare any
+multiple-cylinder power plant as a series of single-cylinder engines
+joined one behind the other and so coupled that one will deliver power
+and produce useful energy at the crank-shaft where the other leaves off.
+The same fundamental laws governing the action of a single cylinder
+obtain when a number are employed, and the sequence of operation is the
+same in all members, except that the necessary functions take place at
+different times. If, for instance, all the cylinders of a four-cylinder
+motor were fired at the same time, one would obtain the same effect as
+though a one-piston engine was used, which had a piston displacement
+equal to that of the four smaller members. As is the case with a
+single-cylinder engine, the motor would be out of correct mechanical
+balance because all the connecting rods would be placed on crank-pins
+that lie in the same plane. A very large fly-wheel would be necessary to
+carry the piston through the idle strokes, and large balance weights
+would be fitted to the crank-shaft in an effort to compensate for the
+weight of the four pistons, and thus reduce vibratory stresses which
+obtain when parts are not in correct balance.
+
+There would be no advantage gained by using four cylinders in this
+manner, and there would be more loss of heat and more power consumed in
+friction than in a one-piston motor of the same capacity. This is the
+reason that when four cylinders are used the arrangement of crank-pins
+is always as shown at Fig. 23, B--i.e., two pistons are up, while the
+other two are at the bottom of the stroke. With this construction, we
+have seen that it is possible to string out the explosions so that there
+will always be one cylinder applying power to the crank-shaft. The
+explosions are spaced equally. The parts are in correct mechanical
+balance because two pistons are on the upstroke while the other two are
+descending. Care is taken to have one set of moving members weigh
+exactly the same as the other. With a four-cylinder engine one has
+correct balance and continuous application of energy. This insures a
+smoother running motor which has greater efficiency than the simpler
+one-, two-, and three-cylinder forms previously described. Eliminating
+the stresses which would obtain if we had an unbalanced mechanism and
+irregular power application makes for longer life. Obviously a large
+number of relatively light explosions will produce less wear and strain
+than would a lesser number of powerful ones. As the parts can be built
+lighter if the explosions are not heavy, the engine can be operated at
+higher rotative speeds than when large and cumbersome members are
+utilized. Four-cylinder engines intended for aviation work have been
+built according to the designs shown at Fig. 24, but these forms are
+unconventional and seldom if ever used.
+
+[Illustration: Fig. 24.--Showing Three Possible Though Unconventional
+Arrangements of Four-Cylinder Engines.]
+
+The six-cylinder type of motor, the action of which is shown at Fig. 23,
+C, is superior to the four-cylinder, inasmuch as the power strokes
+overlap, and instead of having two explosions each revolution we have
+three explosions. The conventional crank-shaft arrangement in a
+six-cylinder engine is just the same as though one used two
+three-cylinder shafts fastened together, so pistons 1 and 6 are on the
+same plane as are pistons 2 and 5. Pistons 3 and 4 also travel together.
+With the cranks arranged as outlined at Fig. 23, C, the firing order is
+one, five, three, six, two, four. The manner in which the power strokes
+overlap is clearly shown in the diagram. An interesting comparison is
+also made in the diagrams at Fig. 25 and in the upper corner of Fig. 23,
+C.
+
+[Illustration: Fig. 25.--Diagrams Outlining Advantages of Multiple
+Cylinder Motors, and Why They Deliver Power More Evenly Than Single
+Cylinder Types.]
+
+A rectangle is divided into four columns; each of these corresponds to
+one hundred and eighty degrees, or half a revolution. Thus the first
+revolution of the crank-shaft is represented by the first two columns,
+while the second revolution is represented by the last two. Taking the
+portion of the diagram which shows the power impulse in a one-cylinder
+engine, we see that during the first revolution there has been no power
+impulse. During the first half of the second revolution, however, an
+explosion takes place and a power impulse is obtained. The last portion
+of the second revolution is devoted to exhausting the burned gases, so
+that there are three idle strokes and but one power stroke. The effect
+when two cylinders are employed is shown immediately below.
+
+[Illustration: Fig. 26.--Diagrams Showing Duration of Events for a
+Four-Stroke Cycle, Six-Cylinder Engine.]
+
+Here we have one explosion during the first half of the first revolution
+in one cylinder and another during the first half of the second
+revolution in the other cylinder. With a four-cylinder engine there is
+an explosion each half revolution, while in a six-cylinder engine there
+is one and one-half explosions during each half revolution. When six
+cylinders are used there is no lapse of time between power impulses, as
+these overlap and a continuous and smooth-turning movement is imparted
+to the crank shaft. The diagram shown at Fig. 26, prepared by E. P.
+Pulley, can be studied to advantage in securing an idea of the
+coordination of effort that takes place in an engine of the six-cylinder
+type.
+
+
+ACTUAL DURATION OF DIFFERENT STROKES
+
+[Illustration: Fig. 27.--Diagram Showing Actual Duration of Different
+Strokes in Degrees.]
+
+In the diagrams previously presented the writer has assumed, for the
+sake of simplicity, that each stroke takes place during half of one
+revolution of the crank-shaft, which corresponds to a crank-pin travel
+of one hundred and eighty degrees. The actual duration of these strokes
+is somewhat different. For example, the inlet stroke is usually a trifle
+more than a half revolution, and the exhaust is always considerably
+more. The diagram showing the comparative duration of the strokes is
+shown at Fig. 27. The inlet valve opens ten degrees after the piston
+starts to go down and remains open thirty degrees after the piston has
+reached the bottom of its stroke. This means that the suction stroke
+corresponds to a crank-pin travel of two hundred degrees, while the
+compression stroke is measured by a movement of but one hundred and
+fifty degrees. It is common practice to open the exhaust valve before
+the piston reaches the end of the power stroke so that the actual
+duration of the power stroke is about one hundred and forty degrees,
+while the exhaust stroke corresponds to a crank-pin travel of two
+hundred and twenty-five degrees. In this diagram, which represents
+proper time for the valves to open and close, the dimensions in inches
+given are measured on the fly-wheel and apply only to a certain
+automobile motor. If the fly-wheel were smaller ten degrees would take
+up less than the dimensions given, while if the fly-wheel was larger a
+greater space on its circumference would represent the same crank-pin
+travel. Aviation engines are timed by using a timing disc attached to
+the crank-shaft as they are not provided with fly-wheels. Obviously, the
+distance measured in inches will depend upon the diameter of the disc,
+though the number of degrees interval would not change.
+
+[Illustration: Fig. 28.--Another Diagram to Facilitate Understanding
+Sequence of Functions in Six-Cylinder Engine.]
+
+
+EIGHT- AND TWELVE-CYLINDER V ENGINES
+
+Those who have followed the development of the gasoline engine will
+recall the arguments that were made when the six-cylinder motor was
+introduced at a time that the four-cylinder type was considered
+standard. The arrival of the eight-cylinder has created similar futile
+discussion of its practicability as this is so clearly established as to
+be accepted without question. It has been a standard power plant for
+aeroplanes for many years, early exponents having been the Antoinette,
+the Woolsley, the Renault, the E. N. V. in Europe and the Curtiss in the
+United States.
+
+[Illustration: Fig. 29.--Types of Eight-Cylinder Engines Showing the
+Advantage of the V Method of Cylinder Placing.]
+
+The reason the V type shown at Fig. 29, A is favored is that the
+"all-in-line form" which is shown at Fig. 29, B is not practical for
+aircraft because of its length. Compared to the standard four-cylinder
+engine it is nearly twice as long and it required a much stronger and
+longer crank-shaft. It will be evident that it could not be located to
+advantage in the airplane fuselage. These undesirable factors are
+eliminated in the V type eight-cylinder motor, as it consists of two
+blocks of four cylinders each, so arranged that one set or block is at
+an angle of forty-five degrees from the vertical center line of the
+motor, or at an angle of ninety degrees with the other set. This
+arrangement of cylinders produces a motor that is no longer than a
+four-cylinder engine of half the power would be.
+
+[Illustration: Fig. 30.--Curves Showing Torque of Various Engine Types
+Demonstrate Graphically Marked Advantage of the Eight-Cylinder Type.]
+
+Apparently there is considerable misconception as to the advantage of
+the two extra cylinders of the eight as compared with the six-cylinder.
+It should be borne in mind that the multiplication in the number of
+cylinders noticed since the early days of automobile development has not
+been for solely increasing the power of the engine, but to secure a more
+even turning movement, greater flexibility and to eliminate destructive
+vibration. The ideal internal combustion motor, is the one having the
+most uniform turning movement with the least mechanical friction loss.
+Study of the torque outlines or plotted graphics shown at Figs. 25 and
+30 will show how multiplication of cylinders will produce steady power
+delivery due to overlapping impulses. The most practical form would be
+that which more nearly conforms to the steady running produced by a
+steam turbine or electric motor. The advocates of the eight-cylinder
+engine bring up the item of uniform torque as one of the most important
+advantages of the eight-cylinder design. A number of torque diagrams are
+shown at Fig. 30. While these appear to be deeply technical, they may be
+very easily followed when their purpose is explained. At the top is
+shown the torque diagram of a single-cylinder motor of the four-cycle
+type. The high point in the line represents the period of greatest
+torque or power generation, and it will be evident that this occurs
+early in the first revolution of the crank-shaft. Below this diagram is
+shown a similar curve except that it is produced by a four-cylinder
+engine. Inspection will show that the turning-moment is much more
+uniform than in the single cylinder; similarly, the six-cylinder
+diagram is an improvement over the four, and the eight-cylinder diagram
+is an improvement over the six-cylinder.
+
+[Illustration: Fig. 31.--Diagrams Showing How Increasing Number of
+Cylinders Makes for More Uniform Power Application.]
+
+The reason that practically continuous torque is obtained in an
+eight-cylinder engine is that one cylinder fires every ninety degrees of
+crank-shaft rotation, and as each impulse lasts nearly seventy-five per
+cent. of the stroke, one can easily appreciate that an engine that will
+give four explosions per revolution of the crank-shaft will run more
+uniformly than one that gives but three explosions per revolution, as
+the six-cylinder does, and will be twice as smooth running as a
+four-cylinder, in which but two explosions occur per revolution of the
+crank-shaft. The comparison is so clearly shown in graphical diagrams
+and in Fig. 31 that further description is unnecessary.
+
+Any eight-cylinder engine may be considered a "twin-four,"
+twelve-cylinder engines may be considered "twin sixes."
+
+[Illustration: Fig. 32.--How the Angle Between the Cylinders of an
+Eight- and Twelve-Cylinder V Motor Varies.]
+
+The only points in which an eight-cylinder motor differs from a
+four-cylinder is in the arrangement of the connecting rod, as in many
+designs it is necessary to have two rods working from the same
+crank-pin. This difficulty is easily overcome in some designs by
+staggering the cylinders and having the two connecting rod big ends of
+conventional form side by side on a common crank-pin. In other designs
+one rod is a forked form and works on the outside of a rod of the
+regular pattern. Still another method is to have a boss just above the
+main bearing on one connecting rod to which the lower portion of the
+connecting rod in the opposite cylinder is hinged. As the eight-cylinder
+engine may actually be made lighter than the six-cylinder of equal
+power, it is possible to use smaller reciprocating parts, such as
+pistons, connecting rods and valve gear, and obtain higher engine speed
+with practically no vibration. The firing order in nearly every case is
+the same as in a four-cylinder except that the explosions occur
+alternately in each set of cylinders. The firing order of an
+eight-cylinder motor is apt to be confusing to the motorist,
+especially if one considers that there are eight possible sequences. The
+majority of engineers favor the alternate firing from side to side.
+Firing orders will be considered in proper sequence.
+
+[Illustration: Fig. 33.--The Hall-Scott Four-Cylinder 100 Horse-Power
+Aviation Motor.]
+
+[Illustration: Fig. 34.--Two Views of the Duesenberg Sixteen Valve
+Four-Cylinder Aviation Motor.]
+
+The demand of aircraft designers for more power has stimulated designers
+to work out twelve-cylinder motors. These are high-speed motors
+incorporating all recent features of design in securing light
+reciprocating parts, large valve openings, etc. The twelve-cylinder
+motor incorporates the best features of high-speed motor design and
+there is no need at this time to discuss further the pros and cons of
+the twelve-cylinder versus the eight or six, because it is conceded by
+all that there is the same degree of steady power application in the
+twelve over the eight as there would be in the eight over the six. The
+question resolves itself into having a motor of high power that will
+run with minimum vibration and that produces smooth action. This is well
+shown by diagrams at Fig. 31. It should be remembered that if an
+eight-cylinder engine will give four explosions per revolution of the
+fly-wheel, a twelve-cylinder type will give six explosions per
+revolution, and instead of the impulses coming 90 degrees crank travel
+apart, as in the case of the eight-cylinder, these will come but 60
+degrees of crank travel apart in the case of the twelve-cylinder. For
+this reason, the cylinders of a twelve are usually separated by 60
+degrees while the eight has the blocks spaced 90 degrees apart. The
+comparison can be easily made by comparing the sectional views of Vee
+engines at Fig. 32. When one realizes that the actual duration of the
+power stroke is considerably greater than 120 degrees crank travel, it
+will be apparent that the overlapping of explosions must deliver a very
+uniform application of power. Vee engines have been devised having the
+cylinders spaced but 45 degrees apart, but the explosions cannot be
+timed at equal intervals as when 90 degrees separate the cylinder center
+lines.
+
+[Illustration: Fig. 35.--The Hall-Scott Six-Cylinder Aviation Engine.]
+
+
+RADIAL CYLINDER ARRANGEMENTS
+
+[Illustration: Fig. 36.--The Curtiss Eight-Cylinder, 200 Horse-Power
+Aviation Engine.]
+
+While the fixed cylinder forms of engines, having the cylinders in
+tandem in the four- and six-cylinder models as shown at Figs. 33 to 35
+inclusive and the eight-cylinder V types as outlined at Figs. 36 and 37
+have been generally used and are most in favor at the present time,
+other forms of motors having unconventional cylinder arrangements have
+been devised, though most of these are practically obsolete. While many
+methods of decreasing weight and increasing mechanical efficiency of a
+motor are known to designers, one of the first to be applied to the
+construction of aeronautical power plants was an endeavor to group the
+components, which in themselves were not extremely light, into a form
+that would be considerably lighter than the conventional design. As an
+example, we may consider those multiple-cylinder forms in which the
+cylinders are disposed around a short crank-case, either radiating from
+a common center as at Fig. 38 or of the fan shape shown at Fig. 39. This
+makes it possible to use a crank-case but slightly larger than that
+needed for one or two cylinders and it also permits of a corresponding
+decrease in length of the crank-shaft. The weight of the engine is
+lessened because of the reduction in crank-shaft and crank-case weight
+and the elimination of a number of intermediate bearings and their
+supporting webs which would be necessary with the usual tandem
+construction. While there are six power impulses to every two
+revolutions of the crank-shaft, in the six-cylinder engine, they are
+not evenly spaced as is possible with the conventional arrangement.
+
+[Illustration: Fig. 37.--The Sturtevant Eight-Cylinder, High Speed
+Aviation Motor.]
+
+[Illustration: Fig. 38.--Anzani 40-50 Horse-Power Five-Cylinder Air
+Cooled Engine.]
+
+In the Anzani form, which is shown at Fig. 38, the crank-case is
+stationary and a revolving crank-shaft is employed as in conventional
+construction. The cylinders are five in number and the engine develops
+40 to 50 H.P. with a weight of 72 kilograms or 158.4 lbs. The cylinders
+are of the usual air-cooled form having cooling flanges only part of the
+way down the cylinder. By using five cylinders it is possible to have
+the power impulses come regularly, they coming 145 deg. crank-shaft
+travel apart, the crank-shaft making two turns to every five explosions.
+The balance is good and power output regular. The valves are placed
+directly in the cylinder head and are operated by a common pushrod.
+Attention is directed to the novel method of installing the carburetor
+which supplies the mixture to the engine base from which inlet pipes
+radiate to the various cylinders. This engine is used on French school
+machines.
+
+[Illustration: Fig. 39.--Unconventional Six-Cylinder Aircraft Motor of
+Masson Design.]
+
+In the form shown at Fig. 39 six cylinders are used, all being placed
+above the crank-shaft center line. This engine is also of the air-cooled
+form and develops 50 H. P. and weighs 105 kilograms, or 231 lbs. The
+carburetor is connected to a manifold casting attached to the engine
+base from which the induction pipes radiate to the various cylinders.
+The propeller design and size relative to the engine is clearly shown in
+this view. While flights have been made with both of the engines
+described, this method of construction is not generally followed and has
+been almost entirely displaced abroad by the revolving motors or by the
+more conventional eight-cylinder V engines. Both of the engines shown
+were designed about eight years ago and would be entirely too small and
+weak for use in modern airplanes intended for active duty.
+
+
+ROTARY ENGINES
+
+[Illustration: Fig. 40.--The Gnome Fourteen-Cylinder Revolving Motor.]
+
+Rotary engines such as shown at Fig. 40 are generally associated with
+the idea of light construction and it is rather an interesting point
+that is often overlooked in connection with the application of this idea
+to flight motors, that the reason why rotary engines are popularly
+supposed to be lighter than the others is because they form their own
+fly-wheel, yet on aeroplanes, engines are seldom fitted with a fly-wheel
+at all. As a matter of fact the Gnome engine is not so light because it
+is a rotary motor, and it is a rotary motor because the design that has
+been adopted as that most conducive to lightness is also most suited to
+an engine working in this way. The cylinders could be fixed and
+crank-shaft revolve without increasing the weight to any extent. There
+are two prime factors governing the lightness of an engine, one being
+the initial design, and the other the quality of the materials employed.
+The consideration of reducing weight by cutting away metal is a
+subsidiary method that ought not to play a part in standard practice,
+however useful it may be in special cases. In the Gnome rotary engine
+the lightness is entirely due to the initial design and to the materials
+employed in manufacture. Thus, in the first case, the engine is a radial
+engine, and has its seven or nine cylinders spaced equally around a
+crank-chamber that is no wider or rather longer than would be required
+for any one of the cylinders. This shortening of the crank-chamber not
+only effects a considerable saving of weight on its own account, but
+there is a corresponding saving in the shafts and other members, the
+dimensions of which are governed by the size of the crank-chamber. With
+regard to materials, nothing but steel is used throughout, and most of
+the metal is forged chrome nickel steel. The beautifully steady running
+of the engine is largely due to the fact that there are literally no
+reciprocating parts in the absolute sense, the apparent reciprocation
+between the pistons and cylinders being solely a relative reciprocation
+since both travel in circular paths, that of the pistons, however, being
+electric by one-half of the stroke length to that of the cylinder.
+
+While the Gnome engine has many advantages, on the other hand the head
+resistance offered by a motor of this type is considerable; there is a
+large waste of lubricating oil due to the centrifugal force which tends
+to throw the oil away from the cylinders; the gyroscopic effect of the
+rotary motor is detrimental to the best working of the aeroplane, and
+moreover it requires about seven per cent. of the total power developed
+by the motor to drive the revolving cylinders around the shaft. Of
+necessity, the compression of this type of motor is rather low, and an
+additional disadvantage manifests itself in the fact that there is as
+yet no satisfactory way of muffling the rotary type of motor. The modern
+Gnome engine has been widely copied in various European countries, but
+its design was originated in America, the early Adams-Farwell engine
+being the pioneer form. It has been made in seven- and nine-cylinder
+types and forms of double these numbers. The engine illustrated at Fig.
+40 is a fourteen-cylinder form. The simple engines have an odd number of
+cylinders in order to secure evenly spaced explosions. In the
+seven-cylinder, the impulses come 102.8 deg. apart. In the nine-cylinder
+form, the power strokes are spaced 80 deg. apart. The fourteen-cylinder
+engine is virtually two seven-cylinder types mounted together, the
+cranks being just the same as in a double cylinder opposed motor, the
+explosions coming 51.4 deg. apart; while in the eighteen-cylinder model the
+power impulses come every 40 deg. cylinder travel. Other rotary motors have
+been devised, such as the Le Rhone and the Clerget in France and several
+German copies of these various types. The mechanical features of these
+motors will be fully considered later.
+
+
+
+
+CHAPTER V
+
+    Properties of Liquid Fuels--Distillates of Crude Petroleum--
+    Principles of Carburetion Outlined--Air Needed to Burn Gasoline
+    --What a Carburetor Should Do--Liquid Fuel Storage and Supply--
+    Vacuum Fuel Feed--Early Vaporizer Forms--Development of Float
+    Feed Carburetor--Maybach's Early Design--Concentric Float and
+    Jet Type--Schebler Carburetor--Claudel Carburetor--Stewart
+    Metering Pin Type--Multiple Nozzle Vaporizers--Two-Stage
+    Carburetor--Master Multiple Jet Type--Compound Nozzle Zenith
+    Carburetor--Utility of Gasoline Strainers--Intake Manifold
+    Design and Construction--Compensating for Various Atmospheric
+    Conditions--How High Altitude Affects Power--The Diesel System--
+    Notes on Carburetor Installation--Notes on Carburetor
+    Adjustment.
+
+
+There is no appliance that has more material value upon the efficiency
+of the internal combustion motor than the carburetor or vaporizer which
+supplies the explosive gas to the cylinders. It is only in recent years
+that engineers have realized the importance of using carburetors that
+are efficient and that are so strongly and simply made that there will
+be little liability of derangement. As the power obtained from the
+gas-engine depends upon the combustion of fuel in the cylinders, it is
+evident that if the gas supplied does not have the proper proportions of
+elements to insure rapid combustion the efficiency of the engine will be
+low. When a gas engine is used as a stationary installation it is
+possible to use ordinary illuminating or natural gas for fuel, but when
+this prime mover is applied to automobiles or airplanes it is evident
+that considerable difficulty would be experienced in carrying enough
+compressed coal gas to supply the engine for even a very short trip.
+Fortunately, the development of the internal-combustion motor was not
+delayed by the lack of suitable fuel.
+
+Engineers were familiar with the properties of certain liquids which
+gave off vapors that could be mixed with air to form an explosive gas
+which burned very well in the engine cylinders. A very small quantity of
+such liquids would suffice for a very satisfactory period of operation.
+The problem to be solved before these liquids could be applied in a
+practical manner was to evolve suitable apparatus for vaporizing them
+without waste. Among the liquids that can be combined with air and
+burned, gasoline is the most volatile and is the fuel utilized by
+internal-combustion engines.
+
+The widely increasing scope of usefulness of the internal-combustion
+motor has made it imperative that other fuels be applied in some
+instances because the supply of gasoline may in time become inadequate
+to supply the demand. In fact, abroad this fuel sells for fifty to two
+hundred per cent. more than it does in America because most of the
+gasoline used must be imported from this country or Russia. Because of
+this foreign engineers have experimented widely with other substances,
+such as alcohol, benzol, and kerosene, but more to determine if they can
+be used to advantage in motor cars than in airplane engines.
+
+
+DISTILLATES OF CRUDE PETROLEUM
+
+Crude petroleum is found in small quantities in almost all parts of the
+world, but a large portion of that produced commercially is derived from
+American wells. The petroleum obtained in this country yields more of
+the volatile products than those of foreign production, and for that
+reason the demand for it is greater. The oil fields of this country are
+found in Pennsylvania, Indiana, and Ohio, and the crude petroleum is
+usually in association with natural gas. This mineral oil is an agent
+from which many compounds and products are derived, and the products
+will vary from heavy sludges, such as asphalt, to the lighter and more
+volatile components, some of which will evaporate very easily at
+ordinary temperatures.
+
+The compounds derived from crude petroleum are composed principally of
+hydrogen and carbon and are termed "Hydrocarbons." In the crude product
+one finds many impurities, such as free carbon, sulphur, and various
+earthy elements. Before the oil can be utilized it must be subjected to
+a process of purifying which is known as refining, and it is during this
+process, which is one of destructive distillation, that the various
+liquids are separated. The oil was formerly broken up into three main
+groups of products as follows: Highly volatile, naphtha, benzine,
+gasoline, eight to ten per cent. Light oils, such as kerosene and light
+lubricating oils seventy to eighty per cent. Heavy oils or residuum five
+to nine per cent. From the foregoing it will be seen that the available
+supply of gasoline is determined largely by the demand existing for the
+light oils forming the larger part of the products derived from crude
+petroleum. New processes have been recently discovered by which the
+lighter oils, such as kerosene, are reduced in proportion and that of
+gasoline increased, though the resulting liquid is neither the high
+grade, volatile gasoline known in the early days of motoring nor the low
+grade kerosene.
+
+
+PRINCIPLES OF CARBURETION OUTLINED
+
+The process of carburetion is combining the volatile vapors which
+evaporate from the hydrocarbon liquids with certain proportions of air
+to form an inflammable gas. The quantities of air needed vary with
+different liquids and some mixtures burn quicker than do other
+combinations of air and vapor. Combustion is simply burning and it may
+be rapid, moderate or slow. Mixtures of gasoline and air burn quickly,
+in fact the combustion is so rapid that it is almost instantaneous and
+we obtain what is commonly termed an "explosion." Therefore the
+explosion of gas in the automobile engine cylinder which produces the
+power is really a combination of chemical elements which produce heat
+and an increase in the volume of the gas because of the increase in
+temperature.
+
+If the gasoline mixture is not properly proportioned the rate of
+burning will vary, and if the mixture is either too rich or too weak the
+power of the explosion is reduced and the amount of power applied to the
+piston is decreased proportionately. In determining the proper
+proportions of gasoline and air, one must take the chemical composition
+of gasoline into account. The ordinary liquid used for fuel is said to
+contain about eight-four per cent. carbon and sixteen per cent.
+hydrogen. Air is composed of oxygen and nitrogen and the former has a
+great affinity, or combining power, with the two constituents of
+hydrocarbon liquids. Therefore, what we call an explosion is merely an
+indication that oxygen in the air has combined with the carbon and
+hydrogen of the gasoline.
+
+
+AIR NEEDED TO BURN GASOLINE
+
+In figuring the proper volume of air to mix with a given quantity of
+fuel, one takes into account the fact that one pound of hydrogen
+requires eight pounds of oxygen to burn it, and one pound of carbon
+needs two and one-third pounds of oxygen to insure its combustion. Air
+is composed of one part of oxygen to three and one-half portions of
+nitrogen by weight. Therefore for each pound of oxygen one needs to burn
+hydrogen or carbon four and one-half pounds of air must be allowed. To
+insure combustion of one pound of gasoline which is composed of hydrogen
+and carbon we must furnish about ten pounds of air to burn the carbon
+and about six pounds of air to insure combustion of hydrogen, the other
+component of gasoline. This means that to burn one pound of gasoline one
+must provide about sixteen pounds of air.
+
+While one does not usually consider air as having much weight, at a
+temperature of sixty-two degrees Fahrenheit about fourteen cubic feet of
+air will weigh a pound, and to burn a pound of gasoline one would
+require about two hundred cubic feet of air. This amount will provide
+for combustion theoretically, but it is common practice to allow twice
+this amount because the element nitrogen, which is the main constituent
+of air, is an inert gas and instead of aiding combustion it acts as a
+deterrent of burning. In order to be explosive, gasoline vapor must be
+combined with definite quantities of air. Mixtures that are rich in
+gasoline ignite quicker than those which have more air, but these are
+only suitable when starting or when running slowly, as a rich mixture
+ignites much quicker than a weak mixture. The richer mixture of gasoline
+and air not only burns quicker but produces the most heat and the most
+effective pressure in pounds per square inch of piston top area.
+
+The amount of compression of the charge before ignition also has
+material bearing on the force of the explosion. The higher the degree of
+compression the greater the force exerted by the rapid combustion of the
+gas. It may be stated that as a general thing the maximum explosive
+pressure is somewhat more than four times the compression pressure prior
+to ignition. A charge compressed to sixty pounds will have a maximum of
+approximately two hundred and forty pounds; compacted to eighty pounds
+it will produce a pressure of about three hundred pounds on each square
+inch of piston area at the beginning of the power stroke. Mixtures
+varying from one part of gasoline vapor to four of air to others having
+one part of gasoline vapor to thirteen of air can be ignited, but the
+best results are obtained when the proportions are one to five or one to
+seven, as this mixture is said to be the one that will produce the
+highest temperature, the quickest explosion, and the most pressure.
+
+
+WHAT A CARBURETOR SHOULD DO
+
+While it is apparent that the chief function of a carbureting device is
+to mix hydrocarbon vapors with air to secure mixtures that will burn,
+there are a number of factors which must be considered before describing
+the principles of vaporizing devices. Almost any device which permits a
+current of air to pass over or through a volatile liquid will produce a
+gas which will explode when compressed and ignited in the motor
+cylinder. Modern carburetors are not only called upon to supply certain
+quantities of gas, but these must deliver a mixture to the cylinders
+that is accurately proportioned and which will be of proper composition
+at all engine speeds.
+
+[Illustration: Fig. 41.--How Gravity Feed Fuel Tank May Be Mounted Back
+of Engine and Secure Short Fuel Line.]
+
+Flexible control of the engine is sought by varying the engine speed by
+regulating the supply of gas to the cylinders. The power plant should
+run from its lowest to its highest speed without any irregularity in
+torque, i.e., the acceleration should be gradual rather than spasmodic.
+As the degree of compression will vary in value with the amount of
+throttle opening, the conditions necessary to obtain maximum power
+differ with varying engine speeds. When the throttle is barely opened
+the engine speed is low and the gas must be richer in fuel than when the
+throttle is wide open and the engine speed high.
+
+When an engine is turning over slowly the compression has low value and
+the conditions are not so favorable to rapid combustion as when the
+compression is high. At high engine speeds the gas velocity through the
+intake piping is higher than at low speeds, and regular engine action is
+not so apt to be disturbed by condensation of liquid fuel in the
+manifold due to excessively rich mixture or a superabundance of liquid
+in the stream of carbureted air.
+
+
+LIQUID FUEL STORAGE AND SUPPLY
+
+The problem of gasoline storage and method of supplying the carburetor
+is one that is determined solely by design of the airplane. While the
+object of designers should be to supply the fuel to the carburetor by as
+simple means as possible the fuel supply system of some airplanes is
+quite complex. The first point to consider is the location of the
+gasoline tank. This depends upon the amount of fuel needed and the space
+available in the fuselage.
+
+A very simple and compact fuel supply system is shown at Fig. 41. In
+this instance the fuel container is placed immediately back of the
+engine cylinder. The carburetor which is carried as indicated is joined
+to the tank by a short piece of copper or flexible rubber tubing. This
+is the simplest possible form of fuel supply system and one used on a
+number of excellent airplanes.
+
+As the sizes of engines increase and the power plant fuel consumption
+augments it is necessary to use more fuel, and to obtain a satisfactory
+flying radius without frequent landings for filling the fuel tank it is
+necessary to supply large containers.
+
+When a very powerful power plant is fitted, as on battle planes of high
+capacity, it is necessary to carry large quantities of gasoline. In
+order to use a tank of sufficiently large capacity it may be necessary
+to carry it lower than the carburetor. When installed in this manner it
+is necessary to force fuel out of the tank by air pressure or to pump it
+with a vacuum tank because the gasoline tank is lower than the
+carburetor it supplies and the gasoline cannot flow by gravity as in the
+simpler systems. While the pressure and gravity feed systems are
+generally used in airplanes, it may be well to describe the vacuum lift
+system which has been widely applied to motor cars and which may have
+some use in connection with airplanes as these machines are developed.
+
+
+STEWART VACUUM FUEL FEED
+
+One of the marked tendencies has been the adoption of a vacuum fuel feed
+system to draw the gasoline from tanks placed lower than the carburetor
+instead of using either exhaust gas or air pressure to achieve this end.
+The device generally fitted is the Stewart vacuum feed tank which is
+clearly shown in section at Fig. 42. In this system the suction of a
+motor is employed to draw gasoline from the main fuel tank to the
+auxiliary tank incorporated in the device and from this tank the liquid
+flows to the carburetor. It is claimed that all the advantages of the
+pressure system are obtained with very little more complication than is
+found on the ordinary gravity feed. The mechanism is all contained in
+the cylindrical tank shown, which may be mounted either on the front of
+the dash or on the side of the engine as shown.
+
+[Illustration: Fig. 42.--The Stewart Vacuum Fuel Feed Tank.]
+
+The tank is divided into two chambers, the upper one being the filling
+chamber and the lower one the emptying chamber. The former, which is at
+the top of the device, contains the float valve, as well as the pipes
+running to the main fuel container and to the intake manifold. The lower
+chamber is used to supply the carburetor with gasoline and is under
+atmospheric pressure at all times, so the flow of fuel from it is by
+means of gravity only. Since this chamber is located somewhat above the
+carburetor, there must always be free flow of fuel. Atmospheric pressure
+is maintained by the pipes A and B, the latter opening into the air. In
+order that the fuel will be sucked from a main tank to the upper
+chamber, the suction valve must be opened and the atmospheric valve
+closed. Under these conditions the float is at the bottom and the
+suction at the intake manifold produces a vacuum in the tank which draws
+the gasoline from the main tank to the upper chamber. When the upper
+chamber is filled at the proper height the float rises to the top, this
+closing the suction valve and opening the atmospheric valve. As the
+suction is now cut off, the lower chamber is filled by gravity owing to
+there being atmospheric pressure in both upper and lower chambers. A
+flap valve is provided between the two chambers to prevent the gasoline
+in the lower one from being sucked back into the upper one. The
+atmospheric and suction valves are controlled by the levers C and D,
+both of which are pivoted at E, their outer ends being connected by two
+coil springs. It is seen that the arrangement of these two springs is
+such that the float must be held at the extremity of its movement, and
+that it cannot assume an intermediate position.
+
+This intermittent action is required to insure that the upper part of
+the tank may be under atmospheric pressure part of the time for the
+gasoline to flow to the lower chamber. When the level of gasoline drops
+to a certain point, the float falls, thus opening the suction valve and
+closing the atmospheric valve. The suction of the motor then causes a
+flow of fuel from the main container. As soon as the level rises to the
+proper height the float returns to its upper position. It takes about
+two seconds for the chamber to become full enough to raise the float, as
+but .05 gallon is transferred at a time. The pipe running from the
+bottom of the lower chamber to the carburetor extends up a ways, so that
+there is but little chance of dirt or water being carried to the float
+chamber.
+
+If the engine is allowed to stand long enough so that the tank becomes
+empty, it will be replenished after the motor has been cranked over four
+or five times with the throttle closed. The installation of the Stewart
+Vacuum-Gravity System is very simple. The suction pipe is tapped into
+the manifold at a point as near the cylinders as possible, while the
+fuel pipe is inserted into the gasoline tank and runs to the bottom of
+that member. There is a screen at the end of the fuel pipe to prevent
+any trouble due to deposits of sediment in the main container. As the
+fuel is sucked from the gasoline tank a small vent must be made in the
+tank filler cap so that the pressure in the main tank will always be
+that of the atmosphere.
+
+
+EARLY VAPORIZER FORMS
+
+The early types of carbureting devices were very crude and cumbersome,
+and the mixture of gasoline vapor and air was accomplished in three
+ways. The air stream was passed over the surface of the liquid itself,
+through loosely placed absorbent material saturated with liquid, or
+directly through the fuel. The first type is known as the surface
+carburetor and is now practically obsolete. The second form is called
+the "wick" carburetor because the air stream was passed over or through
+saturated wicking. The third form was known as a "bubbling" carburetor.
+While these primitive forms gave fairly good results with the early
+slow-speed engines and the high grade, or very volatile, gasoline which
+was first used for fuel, they would be entirely unsuitable for present
+forms of engines because they would not carburate the lower grades of
+gasoline which are used to-day, and would not supply the modern
+high-speed engines with gas of the proper consistency fast enough even
+if they did not have to use very volatile gasoline. The form of
+carburetor used at the present time operates on a different principle.
+These devices are known as "spraying carburetors." The fuel is reduced
+to a spray by the suction effect of the entering air stream drawing it
+through a fine opening.
+
+The advantage of this construction is that a more thorough amalgamation
+of the gasoline and air particles is obtained. With the earlier types
+previously considered the air would combine with only the more volatile
+elements, leaving the heavier constituents in the tank. As the fuel
+became stale it was difficult to vaporize it, and it had to be drained
+off and fresh fuel provided before the proper mixture would be produced.
+It will be evident that when the fuel is sprayed into the air stream,
+all the fuel will be used up and the heavier portions of the gasoline
+will be taken into the cylinder and vaporized just as well as the more
+volatile vapors.
+
+[Illustration: Fig. 43.--Marine-Type Mixing Valve, by which Gasoline is
+Sprayed into Air Stream Through Small Opening in Air-Valve Seat.]
+
+The simplest form of spray carburetor is that shown at Fig. 43. In this
+the gasoline opening through which the fuel is sprayed into the
+entering air stream is closed by the spring-controlled mushroom valve
+which regulates the main air opening as well. When the engine draws in a
+charge of air it unseats the valve and at the same time the air flowing
+around it is saturated with gasoline particles through the gasoline
+opening. The mixture thus formed goes to the engine through the mixture
+passage. Two methods of varying the fuel proportions are provided. One
+of these consists of a needle valve to regulate the amount of gasoline,
+the other is a knurled screw which controls the amount of air by
+limiting the lift of the jump valve.
+
+
+DEVELOPMENT OF FLOAT-FEED CARBURETOR
+
+The modern form of spraying carburetor is provided with two chambers,
+one a mixing chamber through which the air stream passes and mixes with
+a gasoline spray, the other a float chamber in which a constant level of
+fuel is maintained by simple mechanism. A jet or standpipe is used in
+the mixing chamber to spray the fuel through and the object of the float
+is to maintain the fuel level to such a point that it will not overflow
+the jet when the motor is not drawing in a charge of gas. With the
+simple forms of generator valve in which the gasoline opening is
+controlled by the air valve, a leak anywhere in either valve or valve
+seat will allow the gasoline to flow continuously whether the engine is
+drawing in a charge or not. The liquid fuel collects around the air
+opening, and when the engine inspires a charge it is saturated with
+gasoline globules and is excessively rich. With a float-feed
+construction, which maintains a constant level of gasoline at the right
+height in the standpipe, liquid fuel will only be supplied when drawn
+out of the jet by the suction effect of the entering air stream.
+
+
+MAYBACH'S EARLY DESIGN
+
+The first form of spraying carburetor ever applied successfully was
+evolved by Maybach for use on one of the earliest Daimler engines. The
+general principles of operation of this pioneer float-feed carburetor
+are shown at Fig. 44, A. The mixing chamber and valve chamber were one
+and the standpipe or jet protruded into the mixing chamber. It was
+connected to the float compartment by a pipe. The fuel from the tank
+entered the top of the float compartment and the opening was closed by a
+needle valve carried on top of a hollow metal float. When the level of
+gasoline in the float chamber was lowered the float would fall and the
+needle valve uncover the opening. This would permit the gasoline from
+the tank to flow into the float chamber, and as the chamber filled the
+float would rise until the proper level had been reached, under which
+conditions the float would shut off the gasoline opening. On every
+suction stroke of the engine the inlet valve, which was an automatic
+type, would leave its seat and a stream of air would be drawn through
+the air opening and around the standpipe or jet. This would cause the
+gasoline to spray out of the tube and mix with the entering air stream.
+
+[Illustration: Fig. 44.--Tracing Evolution of Modern Spray Carburetor.
+A--Early Form Evolved by Maybach. B.--Phoenix-Daimler Modification of
+Maybach's Principle. C--Modern Concentric Float Automatic Compensating
+Carburetor.]
+
+The form shown at B was a modification of Maybach's simple device and
+was first used on the Phoenix-Daimler engines. Several improvements are
+noted in this device. First, the carburetor was made one unit by casting
+the float and mixing chambers together instead of making them separate
+and joining them by a pipe, as shown at A. The float construction was
+improved and the gasoline shut-off valve was operated through leverage
+instead of being directly fastened to the float. The spray nozzle was
+surrounded by a choke tube which concentrated the air stream around it
+and made for more rapid air flow at low engine speeds. A conical piece
+was placed over the jet to break up the entering spray into a mist and
+insure more intimate admixture of air and gasoline. The air opening was
+provided with an air cone which had a shutter controlling the opening so
+that the amount of air entering could be regulated and thus vary the
+mixture proportions within certain limits.
+
+
+CONCENTRIC FLOAT AND JET TYPE
+
+The form shown at B has been further improved, and the type shown at C
+is representative of modern single jet practice. In this the float
+chamber and mixing chamber are concentric. A balanced float mechanism
+which insures steadiness of feed is used, the gasoline jet or standpipe
+is provided with a needle valve to vary the amount of gasoline supplied
+the mixture and two air openings are provided. The main air port is at
+the bottom of the vaporizer, while an auxiliary air inlet is provided at
+the side of the mixing chamber. There are two methods of controlling the
+mixture proportions in this form of carburetor. One may regulate the
+gasoline needle or adjust the auxiliary air valve.
+
+
+SCHEBLER CARBURETOR
+
+A Schebler carburetor, which has been used on some airplane engines, is
+shown in Fig. 45. It will be noticed that a metering pin or needle valve
+opens the jet when the air valve opens. The long arm of a leverage is
+connected to the air valve, while the short arm is connected to the
+needle, the reduction in leverage being such that the needle valve is
+made to travel much less than the air valve. For setting the amount of
+fuel passed or the size of the jet orifice when running with the air
+valve closed, there is a screw which raises or lowers the fulcrum of the
+lever and there is also a dash control having the same effect by pushing
+down the fulcrum against a small spring. A long extension is given to
+the venturi tube which is very narrow around the jet orifices, which are
+horizontal and shown at A in the drawing. Fuel enters the float chamber
+through the union M, and the spring P holds the metering pin upward
+against the restraining action of the lever. The air valve may be set by
+an easily adjustable knurled screw shown in the drawing, and fluttering
+of the valve is prevented by the piston dash pot carried in a chamber
+above the valve into which the valve stem projects. The primary air
+enters beneath the jet passage and there is a small throttle in the
+intake to increase the speed of air flow for starting purposes. The
+carburetor is adapted for the use of a hot-air connection to the stove
+around the exhaust pipe and it is recommended that such a fitting be
+supplied. The lever which controls the supply of air through the primary
+air intake is so arranged that if desired it can be connected with a
+linkage on the dash or control column by means of a flexible wire.
+
+[Illustration: Fig. 45.--New Model of Schebler Carburetor With Metering
+Valve and Extended Venturi. Note Mechanical Connection Between Air Valve
+and Fuel Regulating Needle.]
+
+
+THE CLAUDEL (FRENCH) CARBURETOR
+
+[Illustration: Fig. 46.--The Claudel Carburetor.]
+
+This carburetor is of extremely simple construction, because it has no
+supplementary or auxiliary air valve and no moving parts except the
+throttle controlling the gas flow. The construction is already shown in
+Fig. 46. The spray jet is eccentric with a surrounding sleeve or tube
+in which there are two series of small orifices, one at the top and the
+other near the bottom. The former are about level with the spray jet
+opening. The sleeve surrounding the nozzle is closed at the top. The
+air, passing the upper holes in the sleeve, produces a vacuum in the
+sleeve, thereby drawing air in through the bottom holes. It is this
+moving interior column of air that controls the flow of gasoline from
+the nozzle. Owing to the friction of the small passages, the speed of
+air flow through the sleeve does not increase as fast as the speed of
+air flow outside the sleeve, hence there is a tendency for the mixture
+to remain constant. The throttle of this carburetor is of the barrel
+type, and the top of the spray nozzle and its surrounding sleeve are
+located inside the throttle.
+
+
+STEWART METERING PIN CARBURETOR
+
+The carburetor shown at Fig. 47 is a metering type in which the vacuum
+at the jet is controlled by the weight of the metering valve surrounding
+the upright metering pin. The only moving part is the metering valve,
+which rises and falls with the changes in vacuum. The air chamber
+surrounds the metering valve, and there is a mixing chamber above. As
+the valve is drawn up the gasoline passage is enlarged on account of the
+predetermined taper on the metering pin, and the air passage also is
+increased proportionately, giving the correct mixture. A dashpot at the
+bottom of the valve checks flutter. In idling the valve rests on its
+seat, practically closing the air and giving the necessary idling
+mixture. A passage through the valve acts as an aspirating tube. When
+the valve is closed altogether the primary air passes through ducts in
+the valve itself, giving the proper amount for idling. The one
+adjustment consists in raising or lowering the tapered metering pin,
+increasing or decreasing the supply of gasoline. Dash control is
+supplied. This pulls down the metering pin, increasing the gasoline
+flow. The duplex type for eight- and twelve-cylinder motors is the same
+in principle as model 25, but it is a double carburetor synchronized as
+to throttle movements, adjustments, etc. The duplex for aeronautical
+motors is made of cast aluminum alloy.
+
+[Illustration: Fig. 47.--The Stewart Metering Pin Carburetor.]
+
+
+MULTIPLE NOZZLE VAPORIZERS
+
+To secure properly proportioned mixtures some carburetor designers have
+evolved forms in which two or more nozzles are used in a common mixing
+chamber. The usual construction is to use two, one having a small
+opening and placed in a small air tube and used only for low speeds,
+the other being placed in a larger air tube and having a slightly
+augmented bore so that it is employed on intermediate speeds. At high
+speeds both jets would be used in series. Some multiple jet carburetors
+could be considered as a series of these instruments, each one being
+designed for certain conditions of engine action. They would vary from
+small size just sufficient to run the engine at low speed to others
+having sufficient capacity to furnish gas for the highest possible
+engine speed when used in conjunction with the smaller members which
+have been brought into service progressively as the engine speed has
+been augmented. The multiple nozzle carburetor differs from that in
+which a single spray tube is used only in the construction of the mixing
+chamber, as a common float bowl can be used to supply all spray pipes.
+It is common practice to bring the jets into action progressively by
+some form of mechanical connection with the throttle or by automatic
+valves.
+
+The object of any multiple nozzle carburetor is to secure greater
+flexibility and endeavor to supply mixtures of proper proportions at all
+speeds of the engine. It should be stated, however, that while devices
+of this nature lend themselves readily to practical application it is
+more difficult to adjust them than the simpler forms having but one
+nozzle. When a number of jets are used the liability of clogging up the
+carburetor is increased, and if one or more of the nozzles is choked by
+a particle of dirt or water the resulting mixture trouble is difficult
+to detect. One of the nozzles may supply enough gasoline to permit the
+engine to run well at certain speeds and yet not be adequate to supply
+the proper amount of gas under other conditions. In adjusting a multiple
+jet carburetor in which the jets are provided with gasoline regulating
+needles, it is customary to consider each nozzle as a distinct
+carburetor and to regulate it to secure the best motor action at that
+throttle position which corresponds to the conditions under which the
+jet is brought into service. For instance, that supplied the primary
+mixing chamber should be regulated with the throttle partly closed,
+while the auxiliary jet should be adjusted with the throttle fully
+opened.
+
+
+BALL AND BALL TWO-STAGE CARBURETOR
+
+[Illustration: Fig. 48.--The Ball and Ball Two-Stage Carburetor.]
+
+This is a two-stage vaporizing device, hot air being used in the primary
+or initial stage of vaporization and cold air in the supplementary
+stage. Referring to the sectional illustration at Fig. 48, it will be
+seen that there is a hot-air passage with a choke-valve; the primary
+venturi appears at B; J is its gasoline jet, and V is a spring-loaded
+idling valve in a fixed air opening. These parts constitute the primary
+system. In the secondary system A is a cold-air passage, T a butterfly
+valve and J a gasoline jet discharging into the cold-air passage. This
+system is brought into operation by opening the butterfly T. A
+connection between the butterfly T and the throttle, not shown, throws
+the butterfly wide open when the throttle is not quite wide open; at all
+other times the butterfly is held closed by a spring. The cylindrical
+chamber at the right of the mixing chamber has an extension E of reduced
+diameter connecting it with the intake manifold through a passage D. A
+restricted opening connects the float chamber with the cylindrical
+chamber so that the gasoline level is the same in both. A loosely
+fitting plunger P in the cylindrical chamber has an upward extension
+into the small part of the chamber. O is a small air opening and M is a
+passage from the cylindrical chamber to the mixing chamber. Air
+constantly passes through this when the carburetor is in operation. The
+carburetor is really two in one. The primary carburetor is made up of a
+central jet in a venturi passage. The float chamber is eccentric. In the
+air passage there is a fixed opening, and additional air is taken in by
+the opening through suction of a spring-opposed air valve. The second
+stage, which comes into play as soon as the carburetor is called upon
+for additional mixture above low medium speeds, is made up of an
+independent air passage containing another air valve. As the valve is
+opened this jet is uncovered, and air is led past it. For easy starting
+an extra passage leads from the float bowl passage to a point above the
+throttle. All the suction falls upon this passage when the throttle is
+closed. The passage contains a plunger and acts as a pick-up device.
+When the vacuum increases the plunger rises and shuts off the flow of
+gasoline from the intake passage. As the throttle is opened the vacuum
+in the intake passage is broken, and the plunger falls, causing gasoline
+to gather above it. This is immediately drawn through the pick-up
+passage and gives the desired mixture for acceleration.
+
+
+MASTER MULTIPLE-JET CARBURETOR
+
+[Illustration: Fig. 49.--The Master Carburetor.]
+
+This carburetor, shown in detail in Figs. 49 and 50, has been very
+popular in racing cars and aviation engines because of exceptionally
+good pick-up qualities and its thorough atomization of fuel. Its
+principle of operation is the breaking up of the fuel by a series of
+jets, which vary in number from fourteen to twenty-one, according to
+the size of the carburetor. These are uncovered by opening the throttle,
+which is curved--a patented feature--to secure the correct progression
+of jets. The carburetor has an eccentric float chamber, from which the
+gasoline is led to the jet piece from which the jets stand up in a row.
+The tops of these jets are closed until the throttle is opened far
+enough to pass them, which it does progressively. The air opening is at
+the bottom, and the throttle opening is such that a modified venturi is
+formed. The throttle is carried in a cylindrical barrel with the jets
+placed below it, and the passage from the barrel to the intake is
+arranged so that there is no interruption in the flow. For easy starting
+a dash-controlled shutter closes off the air, throwing the suction on
+the jets, thus giving a rich mixture.
+
+[Illustration: Fig. 50.--Sectional View of Master Carburetor Showing
+Parts.]
+
+The only adjustment is for idling, and once that is fixed it need never
+be touched. This is in the form of a screw and regulates the position of
+the throttle when at idling position. The dash control has high-speed,
+normal and rich-starting positions. In installing the Master carburetor
+the float chamber may be turned either toward the radiator or driver's
+seat. If the float is turned toward the radiator, however, a forward lug
+plate should be ordered; otherwise it will be difficult to install the
+control. The throttle lever must go all the way to the stop lug or
+maximum power will not be secured. In adjusting the idle screw it is
+turned in for rich and out for lean.
+
+
+COMPOUND NOZZLE ZENITH CARBURETOR
+
+[Illustration: Fig. 51.--Sectional View of Zenith Compound Nozzle
+Compensating Carburetor.]
+
+The Zenith carburetor, shown at Fig. 51, has become very popular for
+airplane engine use because of its simplicity, as mixture compensation
+is secured by a compensating compound nozzle principle that works very
+well in practice. To illustrate this principle briefly, let us consider
+the elementary type of carburetor or mixing valve, as shown in Fig. 52,
+A. It consists of a single jet or spraying nozzle placed in the path of
+the incoming air and fed from the usual float chamber. It is a natural
+inference to suppose that as the speed of the motor increases, both the
+flow of air and of gasoline will increase in the same proportion.
+Unhappily, such is not the case. There is a law of liquid bodies which
+states that the flow of gasoline from the jet increases under suction
+faster than the flow of air, giving a mixture which grows richer and
+richer--a mixture containing a much higher percentage of gasoline at
+high suction than at low. The tendency is shown by the accompanying
+curve (Fig. 52, B), which gives the ratio of gasoline to air at varying
+speeds from this type of jet. The mixture is practically constant only
+between narrow limits and at very high speed. The most common method of
+correcting this defect is by putting various auxiliary air valves which,
+adding air, tends to dilute this mixture as it gets too rich. It is
+difficult with makeshift devices to gauge this dilution accurately for
+every motor speed.
+
+[Illustration: Fig. 52.--Diagrams Explaining Action of Baverey Compound
+Nozzle Used in Zenith Carburetor.]
+
+Now, if we have a jet which grows richer as the suction increases, the
+opposite type of jet is one which would grow leaner under similar
+conditions. Baverey, the inventor of the Zenith, discovered the
+principle of the constant flow device which is shown in Fig. 52, C. Here
+a certain fixed amount of gasoline determined by the opening I is
+permitted to flow by gravity into the well J open to the air. The
+suction at jet H has no effect upon the gravity compensator I because
+the suction is destroyed by the open well J. The compensator, then,
+delivers a steady rate of flow per unit of time, and as the motor
+suction increases more air is drawn up, while the amount of gasoline
+remains the same and the mixture grows poorer and poorer. Fig. 52, D,
+shows this curve.
+
+By combining these two types of rich and poor mixture carburetors the
+Zenith compound nozzle was evolved. In Fig. 52, E, we have both the
+direct suction or richer type leading through pipe E and nozzle G and
+the "constant flow" device of Baverey shown at J, I, K and nozzle H. One
+counteracts the defects of the other, so that from the cranking of the
+motor to its highest speed there is a constant ratio of air and
+gasoline to supply efficient combustion.
+
+In addition to the compound nozzle the Zenith is equipped with a
+starting and idling well, shown in the cut of Model L carburetor at P
+and J. This terminates in a priming hole at the edge of the butterfly
+valve, where the suction is greatest when this valve is slightly open.
+The gasoline is drawn up by the suction at the priming hole and, mixed
+with the air rushing by the butterfly, gives an ideal slow speed
+mixture. At higher speeds with the butterfly valve opened further the
+priming well ceases to operate and the compound nozzle drains the well
+and compensates correctly for any motor speed.
+
+[Illustration: Fig. 53.--The Zenith Duplex Carburetor for Airplane
+Motors of the V Type.]
+
+With the coming of the double motor containing eight or twelve cylinders
+arranged in two V blocks, the question of good carburetion has been a
+problem requiring much study. The single carburetor has given only
+indifferent results due to the strong cross suction in the inlet
+manifold from one set of cylinders to the other. This naturally led to
+the adoption of two carburetors in which each set of cylinders was
+independently fed by a separate carburetor. Results from this system
+were very good when the two carburetors were working exactly in unison,
+but as it was extremely difficult to accomplish this co-operation,
+especially where the adjustable type was employed, this system never
+gained in favor. The next logical step was the Zenith Duplex, shown at
+Fig. 53. This consists of two separate and distinct carburetors joined
+together so that a common gasoline float chamber and air inlet could be
+used by both. It does away with cross suction in the manifold because
+each set of cylinders has a separate intake of its own. It does away
+with two carburetors and makes for simplicity. The practical application
+of the Zenith carburetor to the Curtiss 90 horse-power OX-2 motor used
+on the JN-4 standard training machine is shown at Fig. 54, which
+outlines a rear view of the engine in question. The carburetor is
+carried low to permit of fuel supply from a gravity tank carried back of
+the motor.
+
+[Illustration: Fig. 54.--Rear View of Curtiss OX-2 90 Horse-Power
+Airplane Motor Showing Carburetor Location and Hot Air Leads.]
+
+
+UTILITY OF GASOLINE STRAINERS
+
+Many carburetors include a filtering screen at the point where the
+liquid enters the float chamber in order to keep dirt or any other
+foreign matter which may be present in the fuel from entering the float
+chamber. This is not general practice, however, and the majority of
+vaporizers do not include a filter in their construction. It is very
+desirable that the dirt should be kept out of the carburetor because it
+may get under the float control fuel valve and cause flooding by keeping
+it raised from its seat. If it finds its way into the spray nozzle it
+may block the opening so that no gasoline will issue or may so constrict
+the passage that only very small quantities of fuel will be supplied the
+mixture. Where the carburetor itself is not provided with a filtering
+screen a simple filter is usually installed in the pipe line between the
+gasoline tank and the float chamber.
+
+Some simple forms of filters and separators are shown at Fig. 55. That
+at A consists of a simple brass casting having a readily detachable
+gauze screen and a settling chamber of sufficient capacity to allow the
+foreign matter to settle to the bottom, from which it is drained out by
+a pet cock. Any water or dirt in the gasoline will settle to the bottom
+of the chamber, and as all fuel delivered to the carburetor must pass
+through the wire gauze screen it is not likely to contain impurities
+when it reaches the float chamber. The heavier particles, such as scale
+from the tank or dirt and even water, all of which have greater weight
+than the gasoline, will sink to the bottom of the chamber, whereas
+light particles, such as lint, will be prevented from flowing into the
+carburetor by the filtering screen.
+
+[Illustration: Fig. 55.--Types of Strainers Interposed Between Vaporizer
+and Gasoline Tank to Prevent Water or Dirt Passing Into Carbureting
+Device.]
+
+The filtering device shown at B is a larger appliance than that shown at
+A, and should be more efficient as a separator because the gasoline is
+forced to pass through three filtering screens before it reaches the
+carburetor. The gasoline enters the device shown at C through a bent
+pipe which leads directly to the settling chamber and from thence
+through a wire gauze screen to the upper compartment which leads to the
+carburetor. The device shown at D is a combination strainer, drain, and
+sediment cup. The filtering screen is held in place by a spring and
+both are removed by taking out a plug at the bottom of the device. The
+shut-off valve at the top of the device is interposed between the
+sediment cup and the carburetor. This separating device is incorporated
+with the gasoline tank and forms an integral part of the gasoline supply
+system. The other types shown are designed to be interposed between the
+gasoline tank and the carburetor at any point in the pipe line where
+they may be conveniently placed.
+
+
+INTAKE MANIFOLD DESIGN AND CONSTRUCTION
+
+On four- and six-cylinder engines and in fact on all multiple-cylinder
+forms, it is important that the piping leading from the carburetor to
+the cylinders be made in such a way that the various cylinders will
+receive their full quota of gas and that each cylinder will receive its
+charge at about the same point in the cycle of operations. In order to
+make the passages direct the bends should be as few as possible, and
+when curves are necessary they should be of large radius because an
+abrupt corner will not only impede gas flow but will tend to promote
+condensation of the fuel. Every precaution should be taken with
+four- and six-cylinder engines to insure equitable gas distribution to
+the valve chambers if regular action of the power plant is desired. If
+the gas pipe has many turns and angles it will be difficult to charge
+all cylinders properly. On some six-cylinder aviation engines, two
+carburetors are used because of trouble experienced with manifolds
+designed for one carburetor. Duplex carburetors are necessary to secure
+the best results from eight- and twelve-cylinder V engines.
+
+The problem of intake piping is simplified to some extent on block
+motors where the intake passage is cored in the cylinder casting and
+where but one short pipe is needed to join this passage to the
+carburetor. If the cylinders are cast in pairs a simple pipe of T or Y
+form can be used with success. When the engine is of a type using
+individual cylinder castings, especially in the six-cylinder power
+plants, the proper application and installation of suitable piping is a
+difficult problem. The reader is referred to the various engine designs
+outlined to ascertain how the inlet piping has been arranged on
+representative aviation engines. Intake piping is constructed in two
+ways, the most common method being to cast the manifold of brass or
+aluminum. The other method, which is more costly, is to use a built-up
+construction of copper or brass tubing with cast metal elbows and Y
+pieces. One of the disadvantages advanced against the cast manifold is
+that blowholes may exist which produce imperfect castings and which will
+cause mixture troubles because the entering gas from the carburetor,
+which may be of proper proportions, is diluted by the excess air which
+leaks in through the porous casting. Another factor of some moment is
+that the roughness of the walls has a certain amount of friction which
+tends to reduce the velocity of the gases, and when projecting pieces
+are present, such as core wire or other points of metal, these tend to
+collect the drops of liquid fuel and thus promote condensation. The
+advantage of the built-up construction is that the walls of the tubing
+are very smooth, and as the castings are small it is not difficult to
+clean them out thoroughly before they are incorporated in the manifold.
+The tubing and castings are joined together by hard soldering, brazing
+or autogenous welding.
+
+
+COMPENSATING FOR VARYING ATMOSPHERIC CONDITIONS
+
+The low-grade gasoline used at the present time makes it necessary to
+use vaporizers that are more susceptible to atmospheric variations than
+when higher grade and more volatile liquids are vaporized. Sudden
+temperature changes, sometimes being as much as forty degrees rise or
+fall in twelve hours, affect the mixture proportions to some extent, and
+not only changes in temperature but variations in altitude also have a
+bearing on mixture proportions by affecting both gasoline and air. As
+the temperature falls the specific gravity of the gasoline increases
+and it becomes heavier, this producing difficulty in vaporizing. The
+tendency of very cold air is to condense gasoline instead of vaporizing
+it and therefore it is necessary to supply heated air to some
+carburetors to obtain proper mixtures during cold weather. In order that
+the gas mixtures will ignite properly the fuel must be vaporized and
+thoroughly mixed with the entering air either by heat or high velocity
+of the gases. The application of air stoves to the Curtiss OX-2 motor is
+clearly shown at Fig. 54. It will be seen that flexible metal pipes are
+used to convey the heated air to the air intakes of the duplex mixing
+chamber.
+
+[Illustration: Fig. 56.--Chart Showing Diminution of Air Pressure as
+Altitude Increases.]
+
+
+HOW HIGH ALTITUDE AFFECTS POWER
+
+Any internal combustion engine will show less power at high altitudes
+than it will deliver at sea level, and this has caused a great deal of
+questioning. "There is a good reason for this," says a writer in "Motor
+Age," "and it is a physical impossibility for the engine to do
+otherwise. The difference is due to the lower atmospheric pressure the
+higher up we get. That is, at sea level the atmosphere has a pressure of
+14.7 pounds per square inch; at 5,000 feet above sea level the pressure
+is approximately 12.13 pounds per square inch, and at 10,000 feet it is
+10 pounds per square inch. From this it will be seen that the final
+pressure attained after the piston has driven the gas into compressed
+condition ready for firing is lower as the atmospheric pressure drops.
+This means that there is not so much power in the compressed charge of
+gas the higher up you get above sea level.
+
+"For example, suppose the compression ratio to be 4-1/2 to 1; in other
+words, suppose the air space above the piston to have 4-1/2 times the
+volume when the piston is at the bottom of its stroke that it has when
+the piston is at the top of the stroke. That is a common compression
+ratio for an average motor, and is chosen because it is considered to be
+the best for maximum horse-power and in order that the compression
+pressure will not be so high as to cause pre-ignition. Knowing the
+compression ratio, we can determine the final pressure immediately
+before ignition by substituting in the standard formula:
+
+  P^{1} = P(V/V^{1})^{1.3}
+
+in which P is the atmospheric pressure; P^{1} is the final pressure, and
+V/V^{1} is the compression ratio, therefore P^{1} = 14.7 (4.5)^{1.3} =
+104 pounds per square inch, absolute.
+
+"That is, 104 pounds per square inch is the most efficient final
+compression pressure to have for this engine at sea level, since it
+comes directly from the compression ratio.
+
+"Now supposing we consider that the altitude is 7,000 feet above sea
+level. At this height the atmospheric pressure is 11.25 pounds per
+square inch, approximately. In this case we can again substitute in the
+formula, using the new atmospheric pressure figure. The equation
+becomes:
+
+  P^{1} = 11.25 (4.5)^{1.3}--79.4 pounds per square inch, absolute.
+
+"Therefore we now have a final compression pressure of only 79.4 pounds
+per square inch, which is considerably below the pressure we have just
+found to be the most efficient for the motor. The resulting power drop
+is evident.
+
+"It should be borne in mind that these final compression pressures are
+absolute pressures--that is, they include the atmospheric pressure. In
+the first case, to get the pressure above atmospheric you would subtract
+14.7 and in the latter 11.25 would have to be deducted. In other words,
+where the sea level compression is 89.3 pounds per square inch above the
+atmosphere, the same motor will have only a compression pressure of
+68.15 pounds per square inch above the atmosphere at 7,000 feet
+elevation.
+
+"From the above it is evident that in order to bring the final
+compression pressure up to the efficient figure we have determined, a
+different compression ratio would have to be used. That is, the final
+volume would have to be less, and as it is impossible to vary this to
+meet the conditions of altitude, the loss of power cannot be helped
+except by the replacing of the standard pistons with some that are
+longer above the wrist-pin so as to reduce the space above the pistons
+when on top center. Then if the ratio is thereby raised to some such
+figures as 5 to 1, the engine will again have its proper final pressure,
+but it will still not have as much power as it would have at sea level,
+since the horse-power varies directly with the atmospheric pressure,
+final compression being kept constant. That is, at 7,000 feet the
+horse-power of an engine that had 40 horse-power at sea level would be
+equal to
+
+   11.25
+  ------- = 30.6 horse-power.
+   14.7
+
+"If the original compression ratio of 4.5 were retained, the drop in
+horse-power would be even greater than this. These computations and
+remarks will make it clear that the designer who contemplates building
+an airplane for high altitude use should see to it that it is of
+sufficient power to compensate for the drop that is inevitable when it
+is up in the air. This is often illustrated in stationary gas-engine
+installations. An engine that had a sea-level rating amply sufficient
+for the work required, might not be powerful enough when brought up
+several thousand feet." When one considers that airplanes attain heights
+of over 18,000 feet, it will be evident that an ample margin of engine
+power is necessary.
+
+
+THE DIESEL SYSTEM
+
+A system of fuel supply developed by the late Dr. Diesel, a German
+chemist and engineer, is attracting considerable attention at the
+present time on account of the ability of the Diesel engine to burn
+low-grade fuels, such as crude petroleum. In this system the engines are
+built so that very high compressions are used, and only pure air is
+taken into the cylinder on the induction stroke. This is compressed to a
+pressure of about 500 pounds per square inch, and sufficient heat is
+produced by this compression to explode a hydrocarbon mixture. As the
+air which is compressed to this high point cannot burn, the fuel is
+introduced into the cylinder combustion chamber under still higher
+compression than that of the compressed air, and as it is injected in a
+fine stream it is immediately vaporized because of the heat. Just as
+soon as the compressed air becomes thoroughly saturated with the liquid
+fuel, it will explode on account of the degree of heat present in the
+combustion chamber. Such motors have been used in marine and stationary
+applications, but are not practical for airplanes or motor cars because
+of lack of flexibility and great weight in proportion to power
+developed. The Diesel engine is the standard power plant used in
+submarine boats and motor ships, as its efficiency renders it
+particularly well adapted for large units.
+
+
+NOTES ON CARBURETOR INSTALLATION IN AIRPLANES
+
+A writer in "The Aeroplane," an English publication, discourses on some
+features of carburetor installation that may be of interest to the
+aviation student, so portions of the dissertation are reproduced
+herewith.
+
+    "Users of airplanes fitted with ordinary type carburetors will
+    do well to note carefully the way in which these are fitted, for
+    several costly machines have been burnt lately through the sheer
+    carelessness of their users. These particular machines were
+    fitted with a high powered V-type engine, made by a firm which
+    is famous as manufacturers of automobiles _de luxe_. In these
+    engines there are four carburetors, mounted in the V between the
+    cylinders. When the engine is fitted as a tractor, the float
+    chambers are in front of the jet chambers. Consequently, when
+    the tail of the machine is resting on the ground, the jets are
+    lower than the level of the gasoline in the float chamber.
+
+    "Quite naturally, the gasoline runs out of the jet, if it is
+    left turned on when the machine is standing in its normal
+    position, and trickles into the V at the top of the crank-case.
+    Thence it runs down to the tail of the engine, where the
+    magnetos are fitted, and saturates them. If left long enough,
+    the gasoline manages to soak well into the fuselage before
+    evaporating. And what does evaporate makes an inflammable gas in
+    the forward cockpit. Then some one comes along and starts up the
+    engine. The spark-gap of the magneto gives one flash, and the
+    whole front of the machine proceeds to give a Fourth of July
+    performance forthwith. Naturally, one safeguard is to turn the
+    petrol off directly the machine lands. Another is never to turn
+    it on till the engine is actually being started up.
+
+    "One would be asking too much of the human boy--who is
+    officially regarded as the only person fit to fly an
+    aeroplane--if one depended upon his memory of such a detail to
+    save his machine, though one might perhaps reasonably expect the
+    older pilots to remember not to forget. Even so, other means of
+    prevention are preferable, for fire is quite as likely to occur
+    from just the same cause if the engine happens to be a trifle
+    obstinate in starting, and so gives the carburetors several
+    minutes in which to drip--in which operation they would probably
+    be assisted by air-mechanics 'tickling' them.
+
+    "One way out of the trouble is to fit drip tins under the jet
+    chamber to catch the gasoline as it falls. This is all very well
+    just to prevent fire while the machine is being started up, but
+    it will not save it if it is left standing with the tail on the
+    ground and the petrol turned on, for the drip tins will then
+    fill up and run over. And if it catches then, the contents of
+    the drip tins merely add fuel to the fire.
+
+
+    _Reversing Carburetors_
+
+    "Yet another way is to turn the carburetors round, so that the
+    float chambers are behind the jets, and so come below them when
+    the tail is on the ground, thus cutting off the gasoline low
+    down in the jets. There seems to be no particular mechanical
+    difficulty about this, though I must confess that I did not note
+    very carefully whether the reversal of the float chambers would
+    make them foul any other fittings on the engine. It has been
+    argued, however, that doing this would starve the engine of
+    gasoline when climbing at a steep angle, as the gasoline would
+    then be lowered in the jets and need more suction to get into
+    the cylinders. This is rather a pretty point of amateur motor
+    mechanics to discuss, for, obviously, when the same engine is
+    used as a 'pusher' instead of a tractor, the jets are in front
+    of the floats, and there seems to be no falling off in power.
+
+
+    _Starvation of Mixture_
+
+    "Moreover, the higher a machine goes the lower is the
+    atmospheric pressure, and, consequently, the less is the amount
+    of air sucked in at each induction stroke. This means, of
+    course, that with the gasoline supply the mixture at high
+    altitudes is too rich, so that, in order to get precisely the
+    right mixture when very high up, it is necessary to reduce the
+    gasoline supply by screwing down the needle valve between the
+    tank and the carburetor--at least, that has been the experience
+    of various high-flying pilots. No doubt something might be done
+    in the way of forced air feed to compensate for reduced
+    atmospheric pressure, but it remains to be proved whether the
+    extra weight of mechanism involved would pay for the extra power
+    obtained. Variable compression might do something, also, to even
+    things up, but here, also, weight of mechanism has to be
+    considered.
+
+    "In any case, at present, the higher one goes the more the
+    power of the engine is reduced, for less air means a less volume
+    of mixture per cylinder, and as the petrol feed has to be
+    starved to suit the smaller amount of air available, this means
+    further loss of power. I do not know whether anyone has evolved
+    a carburetor which automatically starves the gasoline feed when
+    high up, but it seems possible that when an airplane is sagging
+    about 'up against the ceiling'--as a French pilot described the
+    absolute limit of climb for his particular machine--it might be
+    a good thing to have the jets in front of the float chamber, for
+    then a certain amount of automatic starvation would take place.
+
+    "When a machine is right up at its limiting height, and the
+    pilot is doing his best to make it go higher still, it is
+    probably flying with its tail as low as the pilot dares to let
+    it go, and the lateral and longitudinal controls are on the
+    verge of vanishing, so that if the carburetor jets are behind
+    the float chambers there is bound to be an over-rich mixture in
+    any case. There is even a possibility of a careless or ignorant
+    pilot carrying on in this tail-down position till one set of
+    cylinders cuts out altogether, in which case the carburetor
+    feeding that set may flood over, just as if the machine were on
+    the ground, and the whole thing may catch fire. Whereas, with
+    the jets in front of the floats, though the mixture may starve a
+    trifle, there is, at any rate, no danger of fire through
+    climbing with the tail down.
+
+
+    _A Diving Danger_
+
+    "On the other hand, in a 'pusher' with this type of engine, if
+    the jets are in their normal position--which is in front of the
+    floats--there is danger of fire in a dive. That is to say, if
+    the pilot throttles right down, or switches off and relies on
+    air pressure on his propeller to start the engine again, so that
+    the gasoline is flooding over out of the jets instead of being
+    sucked into the engine, there may be flooding over the magnetos
+    if the dive is very steep and prolonged. In any case, a long
+    dive will mean a certain amount of flooding, and, probably, a
+    good deal of choking and spitting by the engine before it gets
+    rid of the over-rich mixture and picks up steady firing again.
+    Which may indicate to young pilots that it is not good to come
+    down too low under such circumstances, trusting entirely to
+    their engines to pick up at once and get going before they hit
+    the ground.
+
+    "On the whole, it seems that it might be better practice to set
+    the carburetors thwartwise of engines, for then jets and floats
+    would always be at approximately the same level, no matter what
+    the longitudinal position of the machine, and it is never long
+    enough in one position at a big lateral angle to raise any
+    serious carburetor troubles. Car manufacturers who dive
+    cheerfully into the troubled waters of aero-engine designs are
+    a trifle apt to forget that their engines are put into positions
+    on airplanes which would be positively indecent in a motor car.
+    An angle of 1 in 10 is the exception on a car, but it is common
+    on an airplane, and no one ever heard of a car going down a hill
+    of 10 to 1--which is not quite a vertical dive. Therefore, there
+    is every excuse for a well-designed and properly brought-up
+    carburetor misbehaving itself in an aeroplane.
+
+    "It seems, then, that it is up to the manufacturers to produce
+    better carburetors--say, with the jet central with the float.
+    But it also behooves the user to show ordinary common sense in
+    handling the material at present available, and not to make a
+    practice of burning up $25,000 worth or so of airplane just
+    because he is too lazy to turn off his gasoline, or to have the
+    tail of his machine lifted up while he is tinkering with his
+    engines."
+
+
+NOTES ON CARBURETOR ADJUSTMENT
+
+The modern float feed carburetor is a delicate and nicely balanced
+appliance that requires a certain amount of attention and care in order
+to obtain the best results. The adjustments can only be made by one
+possessing an intelligent knowledge of carburetor construction and must
+never be made unless the reason for changing the old adjustment is
+understood. Before altering the adjustment of the leading forms of
+carburetors, a few hints regarding the quality to be obtained in the
+mixture should be given some consideration, as if these are properly
+understood this knowledge will prove of great assistance in adjusting
+the vaporizer to give a good working proportion of fuel and air. There
+is some question regarding the best mixture proportions and it is
+estimated that gas will be explosive in which the proportions of fuel
+vapor and air will vary from one part of the former to a wide range
+included between four and eighteen parts of the latter. A one to four
+mixture is much too rich, while the one in eighteen is much too lean to
+provide positive ignition.
+
+A rich mixture should be avoided because the excessive fuel used will
+deposit carbon and will soot the cylinder walls, combustion chamber
+interior, piston top and valves and also tend to overheat the motor. A
+rich mixture will also seriously interfere with flexible control of the
+engine, as it will choke up on low throttle and run well on open
+throttle when the full amount of gas is needed. A rich mixture may be
+quickly discovered by black smoke issuing from the muffler, the exhaust
+gas having a very pungent odor. If the mixture contains a surplus of air
+there will be popping sounds in the carburetor, which is commonly termed
+"blowing back." To adjust a carburetor is not a difficult matter when
+the purpose of the various control members is understood. The first
+thing to do in adjusting a carburetor is to start the motor and to
+retard the sparking lever so the motor will run slowly leaving the
+throttle about half open. In order to ascertain if the mixture is too
+rich cut down the gasoline flow gradually by screwing down the needle
+valve until the motor commences to run irregularly or misfire. Close the
+needle valves as far as possible without having the engine come to a
+stop, and after having found the minimum amount of fuel gradually
+unscrew the adjusting valve until you arrive at the point where the
+engine develops its highest speed. When this adjustment is secured the
+lock nut is screwed in place so the needle valve will keep the
+adjustment. The next point to look out for is regulation of the
+auxiliary air supply on those types of carburetors where an adjustable
+air valve is provided. This is done by advancing the spark lever and
+opening the throttle. The air valve is first opened or the spring
+tension reduced to a point where the engine misfires or pops back in the
+carburetor. When the point of maximum air supply the engine will run on
+is thus determined, the air valve spring may be tightened by screwing in
+on the regulating screw until the point is reached where an appreciable
+speeding up of the engine is noticed. If both fuel and air valves are
+set right, it will be possible to accelerate the engine speed uniformly
+without interfering with regularity of engine operation by moving the
+throttle lever or accelerator pedal from its closed to its wide open
+position, this being done with the spark lever advanced. All types of
+carburetors do not have the same means of adjustment; in fact, some
+adjust only with the gasoline regulating needle; others must have a
+complete change of spray nozzles; while in others the mixture
+proportions may be varied only by adjustment of the quantity of entering
+air. Changing the float level is effective in some carburetors, but this
+should never be done unless it is certain that the level is not correct.
+Full instructions for locating carburetion troubles will be given in
+proper sequence.
+
+It is a fact well known to experienced repairmen and motorists that
+atmospheric conditions have much to do with carburetor action. It is
+often observed that a motor seems to develop more power at night than
+during the day, a circumstance which is attributed to the presence of
+more moisture in the cooler night air. Likewise, taking a motor from sea
+level to an altitude of 10,000 feet involves using rarefied air in the
+engine cylinders and atmospheric pressures ranging from 14.7 pounds at
+sea level to 10.1 pounds per square inch at the high altitude. All
+carburetors will require some adjustment in the course of any material
+change from one level to another. Great changes of altitude also have a
+marked effect on the cooling system of an airplane. Water boils at 212
+degrees F. only at sea level. At an altitude of 10,000 feet it will boil
+at a temperature nineteen degrees lower, or 193 degrees F.
+
+In high altitudes the reduced atmospheric pressure, for 5,000 feet or
+higher than sea level, results in not enough air reaching the mixture,
+so that either the auxiliary air opening has to be increased, or the
+gasoline in the mixture cut down. If the user is to be continually at
+high altitudes he should immediately purchase either a larger dome or a
+smaller strangling tube, mentioning the size carburetor that is at
+present in use and the type of motor that it is on, including details as
+to the bore and stroke. The smaller strangling tube makes an increased
+suction at the spray nozzle; the air will have to be readjusted to meet
+it and you can use more auxiliary air, which is necessary. The effect
+on the motor without a smaller strangling tube is a perceptible
+sluggishness and failure to speed up to its normal crank-shaft
+revolutions, as well as failure to give power. It means that about
+one-third of the regular speed is cut out. The reduced atmospheric
+pressure reduces the power of the explosion, in that there is not the
+same quantity of oxygen in the combustion chamber as at sea level; to
+increase the amount taken in, you must also increase the gasoline speed,
+which is done by an increased suction through the smaller strangling
+aperture. Some forms of carburetors are affected more than others by
+changes of altitude, which explains why the Zenith is so widely employed
+for airplane engine use. The compensating nozzle construction is not
+influenced as much by changes of altitude as the simpler nozzle types
+are.
+
+
+
+
+CHAPTER VI
+
+    Early Ignition Systems--Electrical Ignition Best--Fundamentals
+    of Magnetism Outlined--Forms of Magneto--Zones of Magnetic
+    Influence--How Magnets are Made--Electricity and Magnetism
+    Related--Basic Principles of Magneto Action--Essential Parts of
+    Magneto and Functions--Transformer Coil Systems--True High
+    Tension Type--The Berling Magneto--Timing and Care--The Dixie
+    Magneto--Spark Plug Design and Application--Two-Spark Ignition--
+    Special Airplane Plug.
+
+
+EARLY IGNITION SYSTEMS
+
+One of the most important auxiliary groups of the gasoline engine
+comprising the airplane power plant and one absolutely necessary to
+insure engine action is the ignition system or the method employed of
+kindling the compressed gas in the cylinder to produce an explosion and
+useful power. The ignition system has been fully as well developed as
+other parts of the engine, and at the present time practically all
+ignition systems follow principles which have become standard through
+wide acceptance.
+
+During the early stages of development of the gasoline engine various
+methods of exploding the charge of combustible gas in the cylinder were
+employed. On some of the earliest engines a flame burned close to the
+cylinder head, and at the proper time for ignition a slide or valve
+moved to provide an opening which permitted the flame to ignite the gas
+back of the piston. This system was practical only on the primitive form
+of gas engines in which the charge was not compressed before ignition.
+Later, when it was found desirable to compress the gas a certain degree
+before exploding it, an incandescent platinum tube in the combustion
+chamber, which was kept in a heated condition by a flame burning in it,
+exploded the gas. The naked flame was not suitable in this application
+because when the slide was opened to provide communication between the
+flame and the gas the compressed charge escaped from the cylinder with
+enough pressure to blow out the flame at times and thus cause irregular
+ignition. When the flame was housed in a platinum tube it was protected
+from the direct action of the gas, and as long as the tube was
+maintained at the proper point of incandescence regular ignition was
+obtained.
+
+Some engineers utilized the property of gases firing themselves if
+compressed to a sufficient degree, while others depended upon the heat
+stored in the cylinder-head to fire the highly compressed gas. None of
+these methods were practical in their application to motor car engines
+because they did not permit flexible engine action which is so
+desirable. At the present time, electrical ignition systems in which the
+compressed gas is exploded by the heating value of the minute electric
+arc or spark in the cylinder are standard, and the general practice
+seems to be toward the use of mechanical producers of electricity rather
+than chemical batteries.
+
+
+ELECTRICAL IGNITION BEST
+
+Two general forms of electrical ignition systems may be used, the most
+popular being that in which a current of electricity under high tension
+is made to leap a gap or air space between the points of the sparking
+plug screwed into the cylinder. The other form, which has been almost
+entirely abandoned in automobile and which was never used with airplane
+engine practice, but which is still used to some extent on marine
+engines, is called the low-tension system because current of low voltage
+is used and the spark is produced by moving electrodes in the combustion
+chamber.
+
+The essential elements of any electrical ignition system, either high or
+low tension, are: First, a simple and practical method of current
+production; second, suitable timing apparatus to cause the spark to
+occur at the right point in the cycle of engine action; third, suitable
+wiring and other apparatus to convey the current produced by the
+generator to the sparking member in the cylinder.
+
+The various appliances necessary to secure prompt ignition of the
+compressed gases should be described in some detail because of the
+importance of the ignition system. It is patent that the scope of a work
+of this character does not permit one to go fully into the theory and
+principles of operation of all appliances which may be used in
+connection with gasoline motor ignition, but at the same time it is
+important that the elementary principles be considered to some extent in
+order that the reader should have a proper understanding of the very
+essential ignition apparatus. The first point considered will be the
+common methods of generating the electricity, then the appliances to
+utilize it and produce the required spark in the cylinder. Inasmuch as
+magneto ignition is universally used in connection with airplane engine
+ignition it will not be necessary to consider battery ignition systems.
+
+
+FUNDAMENTALS OF MAGNETISM OUTLINED
+
+To properly understand the phenomena and forces involved in the
+generation of electrical energy by mechanical means it is necessary to
+become familiar with some of the elementary principles of magnetism and
+its relation to electricity. The following matter can be read with
+profit by those who are not familiar with the subject. Most persons know
+that magnetism exists in certain substances, but many are not able to
+grasp the terms used in describing the operation of various electrical
+devices because of not possessing a knowledge of the basic facts upon
+which the action of such apparatus is based.
+
+Magnetism is a property possessed by certain substances and is
+manifested by the ability to attract and repel other materials
+susceptible to its effects. When this phenomenon is manifested by a
+conductor or wire through which a current of electricity is flowing it
+is termed "electro-magnetism." Magnetism and electricity are closely
+related, each being capable of producing the other. Practically all of
+the phenomena manifested by materials which possess magnetic qualities
+naturally can be easily reproduced by passing a current of electricity
+through a body which, when not under electrical influence, is not a
+magnetic substance. Only certain substances show magnetic properties,
+these being iron, nickel, cobalt and their alloys.
+
+The earliest known substance possessing magnetic properties was a stone
+first found in Asia Minor. It was called the lodestone or leading stone,
+because of its tendency, if arranged so it could be moved freely, of
+pointing one particular portion toward the north. The compass of the
+ancient Chinese mariners was a piece of this material, now known to be
+iron ore, suspended by a light thread or floated on a cork in some
+liquid so one end would point toward the north magnetic pole of the
+earth. The reason that this stone was magnetic was hard to define for a
+time, until it was learned that the earth was one huge magnet and that
+the iron ore, being particularly susceptible, absorbed and retained some
+of this magnetism.
+
+Most of us are familiar with some of the properties of the magnet
+because of the extensive sale and use of small horseshoe magnets as
+toys. As they only cost a few pennies every one has owned one at some
+time or other and has experimented with various materials to see if they
+would be attracted. Small pieces of iron or steel were quickly attracted
+to the magnet and adhered to the pole pieces when brought within the
+zone of magnetic influence. It was soon learned that brass, copper, tin
+or zinc were not affected by the magnet. A simple experiment that serves
+to illustrate magnetic attraction of several substances is shown at A,
+Fig. 57. In this, several balls are hung from a standard or support, one
+of these being of iron, another of steel. When a magnet is brought near
+either of these they will be attracted toward it, while the others will
+remain indifferent to the magnetic force. Experimenters soon learned
+that of the common metals only iron or steel were magnetic.
+
+[Illustration: Fig. 57.--Some Simple Experiments to Demonstrate Various
+Magnetic Phenomena and Clearly Outline Effects of Magnetism and Various
+Forms of Magnets.]
+
+If the ordinary bar or horseshoe magnet be carefully examined, one end
+will be found to be marked N. This indicates the north pole, while the
+other end is not usually marked and is the south pole. If the north pole
+of one magnet is brought near the south pole of another, a strong
+attraction will exist between them, this depending upon the size of the
+magnets used and the air gap separating the poles. If the south pole of
+one magnet is brought close to the end of the same polarity of the other
+there will be a pronounced repulsion of like force. These facts are
+easily proved by the simple experiment outlined at B, Fig. 57. A magnet
+will only attract or influence a substance having similar qualities. The
+like poles of magnets will repel each other because of the obvious
+impossibility of uniting two influences or forces of practically equal
+strength but flowing in opposite directions. The unlike poles of magnets
+attract each other because the force is flowing in the same direction.
+The flow of magnetism is through the magnet from south to north and the
+circuit is completed by the flow of magnetic influence through the air
+gap or metal armature bridging it from the north to the south pole.
+
+
+FORMS OF MAGNETS AND ZONE OF MAGNETIC INFLUENCE DEFINED
+
+Magnets are commonly made in two forms, either in the shape of a bar or
+horseshoe. These two forms are made in two types, simple or compound.
+The latter are composed of a number of magnets of the same form united
+so the ends of like polarity are laced together, and such a construction
+will be more efficient and have more strength than a simple magnet of
+the same weight. The two common forms of simple and compound magnets are
+shown at C, Fig. 57. The zone in which a magnetic influence occurs is
+called the magnetic field, and this force can be graphically shown by
+means of imaginary lines, which are termed "lines of force." As will be
+seen from the diagram at D, Fig. 57, the lines show the direction of
+action of the magnetic force and also show its strength, as they are
+closer together and more numerous when the intensity of the magnetic
+field is at its maximum. A simple method of demonstrating the presence
+of the force is to lay a piece of thin paper over the pole pieces of
+either a bar or horseshoe magnet and sprinkle fine iron filings on it.
+The particles of metal arrange themselves in very much the manner shown
+in the illustrations and prove that the magnetic field actually exists.
+
+The form of magnet used will materially affect the size and area of the
+magnetic field. It will be noted that the field will be concentrated to
+a greater extent with the horseshoe form because of the proximity of the
+poles. It should be understood that these lines have no actual
+existence, but are imaginary and assumed to exist only to show the way
+the magnetic field is distributed. The magnetic influence is always
+greater at the poles than at the center, and that is why a horseshoe or
+U-form magnet is used in practically all magnetos or dynamos. This
+greater attraction at the poles can be clearly demonstrated by
+sprinkling iron filings on bar and U magnets, as outlined at E, Fig. 57.
+A large mass gathers at the pole pieces, gradually tapering down toward
+the point where the attraction is least.
+
+From the diagrams it will be seen that the flow of magnetism is from one
+pole to the other by means of curved paths between them. This circuit is
+completed by the magnetism flowing from one pole to the other through
+the magnet, and as this flow is continued as long as the body remains
+magnetic it constitutes a magnetic circuit. If this flow were
+temporarily interrupted by means of a conductor of electricity moving
+through the field there would be a current of electricity induced in the
+conductor every time it cut the lines of force. There are three kinds of
+magnetic circuits. A non-magnetic circuit is one in which the magnetic
+influence completes its circuit through some substance not susceptible
+to the force. A closed magnetic circuit is one in which the influence
+completes its circuit through some magnetic material which bridges the
+gap between the poles. A compound circuit is that in which the magnetic
+influence passes through magnetic substances and non-magnetic substances
+in order to complete its circuit.
+
+
+HOW IRON AND STEEL BARS ARE MADE MAGNETIC
+
+Magnetism may be produced in two ways, by contact or induction. If a
+piece of steel is rubbed on a magnet it will be found a magnet when
+removed, having a north and south pole and all of the properties found
+in the energizing magnet. This is magnetizing by contact. A piece of
+steel will retain the magnetism imparted to it for a considerable length
+of time, and the influence that remains is known as residual magnetism.
+This property may be increased by alloying the steel with tungsten and
+hardening it before it is magnetized. Any material that will retain its
+magnetic influence after removal from the source of magnetism is known
+as a permanent magnet. If a piece of iron or steel is brought into the
+magnetic field of a powerful magnet it becomes a magnet without actual
+contact with the energizer. This is magnetizing by magnetic induction.
+If a powerful electric current flows through an insulated conductor
+wound around a piece of iron or steel it will make a magnet of it. This
+is magnetizing by electro-magnetic induction. A magnet made in this
+manner is termed an electro-magnet and usually the metal is of such a
+nature that it will not retain its magnetism when the current ceases to
+flow around it. Steel is used in all cases where permanent magnets are
+required, while soft iron is employed in all cases where an intermittent
+magnetic action is desired. Magneto field magnets are always made of
+tungsten steel alloy, so treated that it will retain its magnetism for
+lengthy periods.
+
+
+ELECTRICITY AND MAGNETISM CLOSELY RELATED
+
+There are many points in which magnetism and electricity are alike. For
+instance, air is a medium that offers considerable resistance to the
+passage of both magnetic influence and electric energy, although it
+offers more resistance to the passage of the latter. Minerals like iron
+or steel are very easily influenced by magnetism and easily penetrated
+by it. When one of these is present in the magnetic circuit the
+magnetism will flow through the metal. Any metal is a good conductor for
+the passage of the electric current, but few metals are good conductors
+of magnetic energy. A body of the proper metal will become a magnet due
+to induction if placed in the magnetic field, having a south pole where
+the lines of force enter it and a north pole where they pass out.
+
+We have seen that a magnet is constantly surrounded by a magnetic field
+and that an electrical conductor when carrying a current is also
+surrounded by a field of magnetic influence. Now if the conductor
+carrying a current of electricity will induce magnetism in a bar of iron
+or steel, by a reversal of this process, a magnetized iron or steel bar
+will produce a current of electricity in a conductor. It is upon this
+principle that the modern dynamo or magneto is constructed. If an
+electro-motive force is induced in a conductor by moving it across a
+field of magnetic influence, or by passing a magnetic field near a
+conductor, electricity is said to be generated by magneto-electric
+induction. All mechanical generators of the electric current using
+permanent steel magnets to produce a field of magnetic influence are of
+this type.
+
+
+BASIC PRINCIPLES OF MAGNETO OUTLINED
+
+The accompanying diagram, Fig. 58, will show these principles very
+clearly. As stated on an earlier page, if the lines of force in the
+magnetic field are cut by a suitable conductor an electrical impulse
+will be produced in that conductor. In this simple machine the lines of
+force exist between the poles of a horseshoe magnet. The conductor,
+which in this case is a loop of copper wire, is mounted upon a spindle
+in order that it may be rotated in the magnetic field to cut the lines
+of magnetic influence present between the pole pieces. Both of the ends
+of this loop are connected, one with the insulated drum shown upon the
+shaft, the other to the shaft. Two metal brushes are employed to collect
+the current and cause it to flow through the external circuit. It can
+be seen that when the shaft is turned in the direction of the arrow the
+loop will cut through the lines of magnetic influence and a current will
+be generated therein.
+
+[Illustration: Fig. 58.--Elementary Form of Magneto Showing Principal
+Parts Simplified to Make Method of Current Generation Clear.]
+
+The pressure of the current and the amount produced vary in accordance
+to the rapidity with which the lines of magnetic influence are cut. The
+armature of a practical magneto, therefore, differs materially from that
+shown in the diagram. A large number of loops of wire would be mounted
+upon this shaft in order that the lines of magnetic influence would be
+cut a greater number of times in a given period and a core of iron used
+as a backing for the wire. This would give a more rapid alternating
+current and a higher electro-motive force than would be the case with a
+smaller number of loops of wire.
+
+[Illustration: Fig. 59.--Showing How Strength of Magnetic Influence and
+of the Currents Induced in the Windings of Armature Vary with the
+Rapidity of Changes of Flow.]
+
+The illustrations at Fig. 59 show a conventional double winding
+armature and field magnetic of a practical magneto in part section and
+will serve to more fully emphasize the points previously made. If the
+armature or spindle were removed from between the pole pieces there
+would exist a field of magnetic influence as shown at Fig. 57, but the
+introduction of this component provides a conductor (the iron core) for
+the magnetic energy, regardless of its position, though the facility
+with which the influence will be transmitted depends entirely upon the
+position of the core. As shown at A, the magnetic flow is through the
+main body in a straight line, while at B, which position the armature
+has attained after one-eighth revolution, or 45 degrees travel in the
+direction of the arrow, the magnetism must pass through in the manner
+indicated. At C, which position is attained every half revolution, the
+magnetic energy abandons the longer path through the body of the core
+for the shorter passage offered by the side pieces, and the field thrown
+out by the cross bar disappears. On further rotation of the armature, as
+at D, the body of the core again becomes energized as the magnetic
+influence resumes its flow through it. These changes in the strength of
+the magnetic field when distorted by the armature core, as well as the
+intensity of the energy existing in the field, affect the windings, and
+the electrical energy induced therein corresponds in strength to the
+rapidity with which these changes in magnetic flow occur. The most
+pronounced changes in the strength of the field will occur as the
+armature passes from position B to D, because the magnetic field
+existing around the core will be destroyed and again re-established.
+
+During the most of the armature rotation the changes in strength will be
+slight and the currents induced in the wire correspondingly small; but
+at the instant the core becomes remagnetized, as the armature leaves
+position C, the current produced will be at its maximum, and it is
+necessary to so time the rotation of the armature that at this instant
+one of the cylinders is in condition to be fired. It is imperative that
+the armature be driven in such relation to the crank-shaft that each
+production of maximum current coincides with the ignition point, this
+condition existing twice during each revolution of the armature, or at
+every 180 degrees travel. Each position shown corresponds to 45 degrees
+travel of the armature, or one-eighth of a turn, and it takes just
+three-eighths revolution to change the position from A to that shown at
+D.
+
+
+ESSENTIAL PARTS OF A MAGNETO AND THEIR FUNCTIONS
+
+The magnets which produce the influence that in turn induces the
+electrical energy in the winding or loops of wire on the armature, and
+which may have any even number of opposed poles, are called field
+magnets. The loops of wire which are mounted upon a suitable drum and
+rotate in the field of magnetic influence in order to cut the lines of
+force is called an armature winding, while the core is the metal
+portion. The entire assembly is called the armature. The exposed ends of
+the magnets are called pole pieces and the arrangement used to collect
+the current is either a commutator or a collector. The stationary pieces
+which bear against the collector or commutator and act as terminals for
+the outside circuit are called brushes. These brushes are often of
+copper, or some of its alloys, because copper has a greater electrical
+conductivity than any other metal.
+
+These brushes are nearly always of carbon, which is sometimes
+electroplated with copper to increase its electrical conductivity,
+though cylinders of copper wire gauze impregnated with graphite are
+utilized at times. Carbon is used because it is not so liable to cut the
+metal of the commutator as might be the case if the contact was of the
+metal to metal type. The reason for this is that carbon has the peculiar
+property in that it materially assists in the lubrication of the
+commutator, and being of soft, unctuous composition, will wear and
+conform to any irregularities on the surface of the metal collector
+rings.
+
+The magneto in common use consists of a number of horseshoe magnets
+which are compound in form and attached to suitable cast-iron pole
+pieces used to collect and concentrate the magnetic influence of the
+various magnets. Between these pole pieces an armature rotates. This is
+usually shaped like a shuttle, around which are wound coils of insulated
+wire. These are composed of a large number of turns and the current
+produced depends in great measure upon the size of the wire and the
+number of turns per coil. An armature winding of large wire will deliver
+a current of great amperage, but of small voltage. An armature wound
+with very fine wire will deliver a current of high voltage but of low
+amperage. In the ordinary form of magneto, such as used for ignition,
+the current is alternating in character and the break in the circuit
+should be timed to occur when the armature is at the point of its
+greatest potential or pressure. Where such a generator is designed for
+direct current production the ends of the winding are attached to the
+segments of a commutator, but where the instrument is designed to
+deliver an alternating current one end of the winding is fastened to an
+insulator ring on one end of the armature shaft and the other end is
+grounded on the frame of the machine.
+
+The quantity of the current depends upon the strength of the magnetic
+field and the number of lines of magnetic influence acting through the
+armature. The electro-motive force varies as to the length of the
+armature winding and the number of revolutions at which the armature is
+rotated.
+
+
+THE TRANSFORMER SYSTEM USES LOW VOLTAGE MAGNETO
+
+The magneto in the various systems which employ a transformer coil is
+very similar to a low-tension generator in general construction, and the
+current delivered at the terminals seldom exceeds 100 volts. As it
+requires many times that potential or pressure to leap the gap which
+exists between the points of the conventional spark plug, a separate
+coil is placed in circuit to intensify the current to one of greater
+capacity. The essential parts of such a system and their relation to
+each other are shown in diagrammatic form at Fig. 60 and as a complete
+system at Fig. 61. As is true of other systems the magnetic influence is
+produced by permanent steel magnets clamped to the cast-iron pole pieces
+between which the armature rotates. At the point of greatest potential
+in the armature winding the current is broken by the contact breaker,
+which is actuated by a cam, and a current of higher value is induced in
+the secondary winding of the transformer coil when the low voltage
+current is passed through the primary winding.
+
+[Illustration: Fig. 60.--Diagrams Explaining Action of Low Tension
+Transformer Coil and True High Tension Magneto Ignition Systems.]
+
+[Illustration: Fig. 60A.--Side Sectional View of Bosch High-Tension
+Magneto Shows Disposition of Parts. End Elevation Depicts Arrangement of
+Interruptor and Distributor Mechanism.]
+
+It will be noted that the points of the contact breaker are together
+except for the brief instant when separated by the action of the point
+of the cam upon the lever. It is obvious that the armature winding is
+short-circuited upon itself except when the contact points are
+separated. While the armature winding is thus short-circuited there will
+be practically no generation of current. When the points are separated
+there is a sudden flow of current through the primary winding of the
+transformer coil, inducing a secondary current in the other winding,
+which can be varied in strength by certain considerations in the
+preliminary design of the apparatus. This current of higher potential or
+voltage is conducted directly to the plug if the device is fitted to a
+single-cylinder engine, or to the distributor arm if fitted to a
+multiple-cylinder motor. The distributor consists of an insulator in
+which is placed a number of segments, one for each cylinder to be fired,
+and so spaced that the number of degrees between them correspond to the
+ignition points of the motor. A two-cylinder motor would have two
+segments, a three-cylinder, three segments, and so on within the
+capacity of the instrument. In the illustration a four-cylinder
+distributor is fitted, and the distributing arm is in contact with the
+segment corresponding to the cylinder about to be fired.
+
+[Illustration: Fig. 61.--Berling Two-Spark Dual Ignition System.]
+
+
+TRUE HIGH-TENSION MAGNETOS ARE SELF-CONTAINED
+
+[Illustration: Fig. 62.--Berling Double-Spark Independent System.]
+
+The true high-tension magneto differs from the preceding inasmuch as the
+current of high voltage is produced in the armature winding direct,
+without the use of the separate coil. Instead of but one coil, the
+armature carries two, one of comparatively coarse wire, the other of
+many turns of finer wire. The arrangement of these windings can be
+readily ascertained by reference to the diagram B, Fig. 60, which shows
+the principle of operation very clearly. The simplicity of the ignition
+system is evident by inspection of Fig. 62. One end of the primary
+winding (coarse wire) is coupled or grounded to the armature core, and
+the other passes to the insulated part of the interrupter. While in some
+forms the interrupter or contact breaker mechanism does not revolve, the
+desired motion being imparted to the contact lever to separate the
+points of a revolving cam, in this the cam or tripping mechanism is
+stationary and the contact breaker revolves. This arrangement makes it
+possible to conduct the current from the revolving primary coil to the
+interrupter by a direct connection, eliminating the use of brushes,
+which would otherwise be necessary. In other forms of this appliance
+where the winding is stationary, the interrupter may be operated by a
+revolving cam, though, if desired, the used of a brush at this point
+will permit this construction with a revolving winding.
+
+During the revolution of the armature the grounded lever makes and
+breaks contact with the insulated point, short-circuiting the primary
+winding upon itself until the armature reaches the proper position of
+maximum intensity of current production, at which time the circuit is
+broken, as in the former instance. One end of the secondary winding
+(fine wire) is grounded on the live end of the primary, the other end
+being attached to the revolving arm of the distributor mechanism. So
+long as a closed circuit is maintained feeble currents will pass through
+the primary winding, and so long as the contact points are together this
+condition will exist. When the current reaches its maximum value,
+because of the armature being in the best position, the cam operates the
+interrupter and the points are separated, breaking the short circuit
+which has existed in the primary winding.
+
+The secondary circuit has been open while the distributor arm has moved
+from one contact to another and there has been no flow of energy through
+this winding. While the electrical pressure will rise in this, even if
+the distributor arm contacted with one of the segments, there would be
+no spark at the plug until the contact points separated, because the
+current in the secondary winding would not be of sufficient strength.
+When the interrupter operates, however, the maximum primary current will
+be diverted from its short circuit and can flow to the ground only
+through the secondary winding and spark-plug circuit. The high pressure
+now existing in the secondary winding will be greatly increased by the
+sudden flow of primary current, and energy of high enough potential to
+successfully bridge the gap at the plug is thereby produced in the
+winding.
+
+
+THE BERLING MAGNETO
+
+[Illustration: Fig. 63.--Type DD Berling High Tension Magneto.]
+
+The Berling magneto is a true high tension type delivering two impulses
+per revolution, but it is made in a variety of forms, both single and
+double spark. Its principle of action does not differ in essentials from
+the high tension type previously described. This magneto is used on
+Curtiss aviation engines and will deliver sparks in a positive manner
+sufficient to insure ignition of engines up to 200 horse-power and at
+rotative speeds of the magneto armature up to 4,000 r. p. m. which is
+sufficient to take care of an eight-cylinder V engine running up to
+2,000 r. p. m. The magneto is driven at crank-shaft speed on
+four-cylinder engines, at 1-1/2 times crank-shaft speed on six-cylinder
+engines and at twice crank-shaft speed on eight-cylinder V types. The
+types "D" and "DD" BERLING Magnetos are interchangeable with
+corresponding magnetos of other standard makes. The dimensions of the
+four-, six- and eight-cylinder types "D" and "DD" are all the same.
+
+The ideal method of driving the magneto is by means of flexible direct
+connecting coupling to a shaft intended for the purpose of driving the
+magneto. As the magneto must be driven at a high speed, a coupling of
+some flexibility is preferable. The employment of such a coupling will
+facilitate the mounting of the magneto, because a small inaccuracy in
+the lining up of the magneto with the driving shaft will be taken care
+of by the flexible coupling, whereas with a perfectly rigid coupling the
+line-up of the magneto must be absolutely accurate. Another advantage of
+the flexible coupling is that the vibration of the motor will not be as
+fully transmitted to the armature shaft on the magneto as in case a
+rigid coupling is used. This means prolonged life for the magneto.
+
+The next best method of driving the magneto is by means of a gear keyed
+to the armature shaft. When this method of driving is employed, great
+care must be exercised in providing sufficient clearance between the
+gear on the magneto and the driving gear. If there should be a tight
+spot between these two gears it will react disadvantageously on the
+magneto. The third available method is to drive the magneto by means of
+a chain. This is the least desirable of the three methods and should be
+resorted to only in case of absolute necessity. It is difficult to
+provide sufficient clearance when using a chain without rendering the
+timing less accurate and positive.
+
+[Illustration: Fig. 64.--Wiring Diagrams of Berling Magneto Ignition
+Systems.]
+
+Fig. 64, A shows diagrammatically the circuit of the "D" type two-spark
+independent magneto and the switch used with it. In position OFF the
+primary winding of the magneto is short-circuited and in this position
+the switch serves as an ordinary cut-out or grounding switch. In
+position "1" the switch connects the magneto in such a way that it
+operates as an ordinary single-spark magneto. In this position one end
+of the secondary winding is grounded to the body of the motor. This is
+the starting position. In this position of the switch the entire voltage
+generated in the magneto is concentrated at one spark-plug instead of
+being divided in half. With the motor turning over very slowly, as is
+the case in starting, the full voltage generated by the magneto will
+not in all cases be sufficient to bridge simultaneously two spark gaps,
+but is amply sufficient to bridge one. Also, this position of the switch
+tends to retard the ignition and should be used in starting to prevent
+back-firing. With the switch in position "2" the magneto applies
+ignition to both plugs in each cylinder simultaneously. This is the
+normal running position.
+
+Fig. 64, B shows diagrammatically the circuit of the type "DD" BERLING
+high-tension two-spark dual magneto. This type is recommended for
+certain types of heavy-duty airplane motors, which it is impossible to
+turn over fast enough to give the magneto sufficient speed to generate
+even a single spark of volume great enough to ignite the gas in the
+cylinder. The dual feature consists of the addition to the magneto of a
+battery interrupter. The equipment consists of the magneto, coil and
+special high-tension switch. The coil is intended to operate on six
+volts. Either a storage battery or dry cells may be used.
+
+With the switch in the OFF position, the magneto is grounded, and the
+battery circuit is open. With the switch in the second or battery
+position marked "BAT," one end of the secondary winding of the magneto
+is grounded, and the magneto operates as a single-spark magneto
+delivering high-tension current to the inside distributor, and the
+battery circuit being closed the high-tension current from the coil is
+delivered to the outside distributor. In this position the battery
+current is supplied to one set of spark plugs, no matter how slowly the
+motor is turned over, but as soon as the motor starts, the magneto
+supplies current as a single-spark magneto to the other set of the
+spark-plugs. After the engine is running, the switch should be thrown to
+the position marked "MAG." The battery and coil are then disconnected,
+and the magneto furnishes ignition to both plugs in each cylinder. This
+is the normal running position. Either a non-vibrating coil type "N-1"
+is furnished or a combined vibrating and non-vibrating coil type
+"VN-1."
+
+
+SETTING BERLING MAGNETO
+
+The magneto may be set according to one of two different methods, the
+selection of which is, to some extent, governed by the characteristics
+of the engine, but largely due to the personal preference on the part of
+the user. In the first method described below, the most advantageous
+position of the piston for fully advanced ignition is determined in
+relation to the extreme advanced position of the magneto. In this case,
+the fully retarded ignition will not be a matter of selection, but the
+timing range of the magneto is wide enough to bring the fully retarded
+ignition after top-center position of the piston. The second method for
+the setting of the magneto fixes the fully retarded position of the
+magneto in relation to that position of the piston where fully retarded
+ignition is desired. In this case, the extreme advance position of the
+magneto will not always correspond with the best position of the piston
+for fully advanced ignition, and the amount of advance the magneto
+should have to meet ideal requirements in this respect must be
+determined by experiment.
+
+
+_First Method:_
+
+1. Designate one cylinder as cylinder No. 1.
+
+2. Turn the crank-shaft until the piston in cylinder No. 1 is in the
+position where the fully advanced spark is desired to occur.
+
+3. Remove the cover from the distributor block and turn the armature
+shaft in the direction of rotation of the magneto until the distributor
+finger-brush comes into such a position that this brush makes contact
+with the segment which is connected to the cable terminal marked "1."
+This is either one of the two bottom segments, depending upon the
+direction of rotation.
+
+4. Place the cam housing in extreme advance, i.e., turn the cam housing
+until it stops, in the direction opposite to the direction of rotation
+of the armature. With the cam housing in this position, open the cover.
+
+5. With the armature in the approximate position as described in "3,"
+turn the armature slightly in either direction to such a point that the
+platinum points of the magneto interrupter will just begin to open at
+the end of the cam, adjacent to the fibre lever on the interrupter.
+
+6. With this exact position of the armature, fix the magneto to the
+driving member of the engine.
+
+
+_Second Method:_
+
+1. Designate one cylinder as cylinder No. 1.
+
+2. Turn the crank-shaft until the piston in cylinder No. 1 is in the
+position at which the fully retarded spark is desired to occur.
+
+3. Same as No. 3 under First Method.
+
+4. Place the cam housing in extreme retard, i.e., turn the cam housing
+until it stops, in the same direction as the direction of rotation of
+the armature. With the cam housing in this position, open the cover.
+
+5. Same as No. 5 under First Method.
+
+6. Same as No. 6 under First Method.
+
+
+WIRING THE MAGNETO
+
+The wiring of the magneto is clearly shown by wiring diagram.
+
+First determine the sequence of firing for the cylinders and then
+connect the cables to the spark plug in the cylinders in proper
+sequence, beginning with cylinder No. 1 marked on the distributor block.
+
+The switch used with the independent type must be mounted in such a
+manner that there will be a metallic connection between the frame of the
+magneto and the metal portion of the switch.
+
+It is advisable to use a separate battery, either storage or dry cells,
+as a source of current for the dual equipment. Connecting to the same
+battery that is used with the generator and other electrical equipment
+may cause trouble, as a "ground" in this battery causes the coil to
+overheat.
+
+
+CARE AND MAINTENANCE
+
+
+_Lubrication:_
+
+Use only the very best of oil for the oil cups.
+
+Put five drops of oil in the oil cup at the driving end of the magneto
+for every fifty hours of actual running.
+
+Put five drops of oil in the oil cup at the interrupter end of the
+magneto, located at one side of the cam housing, for every hundred hours
+of actual running.
+
+Lubricate the embossed cams in the cam housing with a thin film of
+vaseline every fifty hours of actual running. Wipe off all superfluous
+vaseline. Never use oil in the interrupter. Do not lubricate any other
+part of the interrupter.
+
+
+_Adjusting the Interrupter:_
+
+With the fibre lever in the center of one of the embossed cams, as at
+Fig. 65, the opening between the platinum contacts should be not less
+than .016" and not more than .020". The gauge riveted to the adjusting
+wrench should barely be able to pass between the contacts when fully
+open. The platinum contacts must be smoothed off with a very fine file.
+When in closed position, the platinum contacts should make contact with
+each other over their entire surfaces.
+
+When inspecting the interrupter, make sure that the ground brush in the
+back of the interrupter base is making good contact with the surface on
+which it rubs.
+
+
+_Cleaning the Distributor:_
+
+The distributor block cover should be removed for inspection every
+twenty-five hours of actual running and the carbon deposit from the
+distributor finger-brush wiped off the distributor block by rubbing with
+a rag or piece of waste dipped in gasoline or kerosene. The
+high-tension terminal brush on the side of the magneto should also be
+carefully inspected for proper tension.
+
+
+LOCATING TROUBLE
+
+Trouble in the ignition system is indicated by the motor "missing,"
+stopping entirely, or by inability to start.
+
+It is safe to assume that the trouble is not in the magneto, and the
+carburetor, gasoline supply and spark-plugs should first be
+investigated.
+
+[Illustration: Fig. 65.--The Berling Magneto Breaker Box Showing Contact
+Points Separated and Interruptor Lever on Cam.]
+
+If the magneto is suspected, the first thing to do is to determine if it
+will deliver a spark. To determine this, disconnect one of the
+high-tension leads from the spark-plug in one of the cylinders and place
+it so that there is approximately 1/16" between the terminal and the
+cylinder frame.
+
+Open the pet cocks on the other cylinders to prevent the engine from
+firing and turn over the engine until the piston is approaching the end
+of the compression stroke in the cylinder from which the cable has been
+removed. Set the magneto in the advance position and rapidly rock the
+engine over the top-center position, observing closely if a spark occurs
+between the end of the high-tension cable and the frame.
+
+If the magneto is of the dual type, the trouble may be either in the
+magneto or in the battery or coil system, therefore disconnect the
+battery and place the switch in the position marked "MAG." The magneto
+will then operate as an independent magneto and should spark in the
+proper manner. After this the battery system should be investigated. To
+test the operation of the battery and coil, examine all connections,
+making sure that they are clean and tight, and then with the switch, in
+the "BAT," rock the piston slowly back and forth. If a type "VN-1" coil
+is used, a shower of sparks should jump between the high-tension cable
+terminal and the cylinder frame when the piston is in the correct
+position for firing. If no spark occurs, remove the cover from the coil
+and see that the vibrating tongue is free. If a type "N-1" coil is used,
+a single spark will occur. The battery should furnish six volts when
+connected to the coil, and this should also be verified.
+
+If the coil still refuses to give a spark and all connections are
+correct, the coil should be replaced and the defective coil returned to
+the manufacturer.
+
+If both magneto and coil give a spark when tested as just described, the
+spark-plugs should be investigated. To do this, disconnect the cables
+and remove the spark-plugs. Then reconnect the cables to the plugs and
+place them so that the frame portions of the plugs are in metallic
+connection with the frame of the motor. Then turn over the motor, thus
+revolving the magneto armature, and see if a spark is produced at the
+spark gaps of the plugs.
+
+The most common defects in spark-plugs are breaking down of the
+insulation, fouling due to carbon, or too large or small a spark gap. To
+clean the plugs a stiff brush and gasoline should be used. The spark
+gap should be about 1/32" and never less than 1/64". Too small a gap may
+have been caused by beads of metal forming due to the heat of the spark.
+Too long a gap may have been caused by the points burning off.
+
+If the magneto and spark plugs are in good condition and the engine does
+not run satisfactorily, the setting should be verified according to
+instructions previously given, and, if necessary, readjusted.
+
+[Illustration: Fig. 66.--The Dixie Model 60 for Six-Cylinder Airplane
+Engine Ignition.]
+
+Be careful to observe that both the type "VN-1" and type "N-1" coils are
+so arranged that the spark occurs on the opening of the contacts of the
+timer. As this is just the reverse of the usual operation, it should be
+carefully noted when any change in the setting of the timer is made. The
+timer on the dual type magneto is adjusted so that the battery spark
+occurs about 5 deg. later than the magneto spark. This provides an
+automatic advance as soon as the switch is thrown to the magneto
+position "MAG." This relative timing can be easily adjusted by removing
+the interrupter and shifting the cam in the direction desired.
+
+
+THE DIXIE MAGNETO
+
+[Illustration: Fig. 67.--Installation Dimensions of Dixie Model 60
+Magneto.]
+
+The Dixie magneto, shown at Fig. 66, operates on a different principle
+than the rotary armature type. It is used on the Hall-Scott and other
+aviation engines. In this magneto the rotating member consists of two
+pieces of magnetic material separated by a non-magnetic center piece.
+This member constitutes true rotating poles for the magnet and rotates
+in a field structure, composed of two laminated field pieces, riveted
+between two non-magnetic rings. The bearings for the rotating poles are
+mounted in steel plates, which lie against the poles of the magnets.
+When the magnet poles rotate, the magnetic lines of force from each
+magnet pole are carried directly to the field pieces and through the
+windings, without reversal through the mass of the rotating member and
+with only a single air gap. There are no losses by flux reversal in the
+rotating part, such as take place in other machines, and this is said
+to account for the high efficiency of the instrument.
+
+[Illustration: Fig. 68.--The Rotating Elements of the Dixie Magneto.]
+
+And this "Mason Principle" involved in the operation of the Dixie is
+simplified by a glance at the field structure, consisting of the
+non-magnetic rings, assembled to which are the field pieces between
+which the rotating poles revolve (see Fig. 68). Rotating between the
+limbs of the magnets, these two pieces of magnetic material form true
+extensions to the poles of the magnets, and are, in consequence,
+_always_ of the _same_ polarity. It will be seen there is no reversal of
+the magnetism through them, and consequently no eddy current or
+hysteresis losses which are present in the usual rotor or inductor
+types. The simplicity features of construction stand out prominently
+here, in that there are no revolving windings, a detail entirely
+differing from the orthodox high-tension instrument. This simplicity
+becomes instantly apparent when it is found that the circuit breaker,
+instead of revolving as it does in other types, is stationary and that
+the whole breaker mechanism is exposed by simply turning the cover
+spring aside and removing cover. This makes inspection and adjustment
+particularly simple, and the fact that no special tool is necessary for
+adjustment of the platinum points--an ordinary small screw-driver is the
+whole "kit of tools" needed in the work of disassembling or
+assembling--is a feature of some value.
+
+[Illustration: Fig. 69.--Suggestions for Adjusting and Dismantling Dixie
+Magneto. A--Screw Driver Adjusts Contact Points. B--Distributor Block
+Removed. C--Taking off Magnets. D--Showing How Easily Condenser and High
+Tension Windings are Removed.]
+
+With dust- and water-protecting casing removed, and one of the magnets
+withdrawn, as in Fig. 69, the winding can be seen with its core resting
+on the field pole pieces and the primary lead attached to its side. An
+important feature of the high-tension winding is that the heads are of
+insulating material, and there is not the tendency for the high-tension
+current to jump to the side as in the ordinary armature type magneto.
+The high-tension current is carried to the distributor by means of an
+insulated block with a spindle, at one end of which is a spring brush
+bearing directly on the winding, thus shortening the path of the
+high-tension current and eliminating the use of rubber spools and
+insulating parts. The moving parts of the magneto need never be
+disturbed if the high-tension winding is to be removed. This winding
+constitutes all of the magneto windings, no external spark coil being
+necessary. The condenser is placed directly above the winding and is
+easily removable by taking out two screws, instead of being placed in an
+armature where it is inaccessible except to an expert, and where it
+cannot be replaced except at the factory whence it emanated.
+
+
+CARE OF THE DIXIE MAGNETO
+
+The bearings of the magneto are provided with oil cups and a few drops
+of light oil every 1,000 miles are sufficient. The breaker lever should
+be lubricated every 1,000 miles with a drop of light oil, applied with a
+tooth-pick. The proper distance between the platinum points when
+separated should not exceed .020 or one-fiftieth of an inch. A gauge of
+the proper size is attached to the screwdriver furnished with the
+magneto. The platinum contacts should be kept clean and properly
+adjusted. Should the contacts become pitted, a fine file should be used
+to smooth them in order to permit them to come into perfect contact. The
+distributor block should be removed occasionally and inspected for an
+accumulation of carbon dust. The inside of the distributor block should
+be cleaned with a cloth moistened with gasoline and then wiped dry with
+a clean cloth. When replacing the block, care must be exercised in
+pushing the carbon brush into the socket. Do not pull out the carbon
+brushes in the distributor because you think there is not enough tension
+on the small brass springs. In order to obtain the most efficient
+results, the normal setting of the spark-plug points should not exceed
+.025 of an inch, and it is advisable to have the gap just right before a
+spark-plug is inserted.
+
+The spark-plug electrodes may be easily set by means of the gauge
+attached to the screwdriver. _The setting of the spark-plug points is an
+important function which is usually overlooked, with the result that the
+magneto is blamed when it is not at fault._
+
+
+TIMING OF THE DIXIE MAGNETO
+
+[Illustration: Fig. 69A.--Sectional Views Outlining Construction of
+Dixie Magneto with Compound Distributor for Eight-Cylinder Engine
+Ignition.]
+
+In order to obtain the utmost efficiency from the engine, the magneto
+must be correctly timed to it. This operation is usually performed when
+the magneto is fitted to the engine at the factory. The correct setting
+may vary according to individuality of the engine, and some engines
+may require an earlier setting in order to obtain the best results.
+However, should the occasion arise to retime the magneto, the procedure
+is as follows: Rotate the crank-shaft of the engine until one of the
+pistons, preferably that of cylinder No. 1, is 1/16 of an inch ahead of
+the end of the compression stroke. With the timing lever in full retard
+position, the driving shaft of the magneto should be rotated in the
+direction in which it will be driven. The circuit breaker should be
+closely observed and when the platinum contact points are about to
+separate, the drive gear or coupling should be secured to the drive
+shaft of the magneto. Care should be taken not to alter the position of
+the magneto shaft when tightening the nut to secure the gear or
+coupling, after which the magneto should be secured to its base. Remove
+the distributor block and determine which terminal of the block is in
+contact with the carbon brush of the distributor finger and connect with
+plug wire leading to No. 1 cylinder to this terminal. Connect the
+remaining plug wires in turn according to the proper sequence of firing
+of the cylinders. (See the wiring diagram for a typical six-cylinder
+engine at Fig. 70.) A terminal on the end of the cover spring of the
+magneto is provided for the purpose of connecting the wire leading to a
+ground switch for stopping the engine.
+
+A special model or type of magneto is made for V engines which use a
+compound distributor construction instead of the simple type on the
+model illustrated and a different interior arrangement permits the
+production of four sparks per revolution of the rotors. This makes it
+possible to run the magneto slower than would be possible with the
+two-spark form. The application of two compound distributor magnetos of
+this type to a Thomas-Morse 135 horse-power motor of the eight-cylinder
+V pattern is clearly shown at Fig. 71.
+
+[Illustration: Fig. 70.--Wiring Diagram of Dixie Magneto Installation on
+Hall-Scott Six-Cylinder 125 Horse-Power Aeronautic Motor.]
+
+
+SPARK-PLUG DESIGN AND APPLICATION
+
+[Illustration: Fig. 71.--How Magneto Ignition is Installed on
+Thomas-Morse 135 Horse-Power Motor.]
+
+With the high-tension system of ignition the spark is produced by a
+current of high voltage jumping between two points which break the
+complete circuit, which would exist otherwise in the secondary coil and
+its external connections. The spark-plug is a simple device which
+consists of two terminal electrodes carried in a suitable shell member,
+which is screwed into the cylinder. Typical spark-plugs are shown in
+section at Fig. 72 and the construction can be easily understood. The
+secondary wire from the coil is attached to a terminal at the top of a
+central electrode member, which is supported in a bushing of some form
+of insulating material. The type shown at A employs a molded porcelain
+as an insulator, while that depicted at B uses a bushing of mica. The
+insulating bushing and electrode are housed in a steel body, which is
+provided with a screw thread at the bottom, by which means it is screwed
+into the combustion chamber.
+
+[Illustration: Fig. 72.--Spark-Plug Types Showing Construction and
+Arrangement of Parts.]
+
+When porcelain is used as an insulating material it is kept from direct
+contact with the metal portion by some form of yielding packing, usually
+asbestos. This is necessary because the steel and porcelain have
+different coefficients of expansion and some flexibility must be
+provided at the joints to permit the materials to expand differently
+when heated. The steel body of the plug which is screwed into the
+cylinder is in metallic contact with it and carries sparking points
+which form one of the terminals of the air gap over which the spark
+occurs. The current entering at the top of the plug cannot reach the
+ground, which is represented by the metal portion of the engine, until
+it has traversed the full length of the central electrode and overcome
+the resistance of the gap between it and the terminal point on the
+shell. The porcelain bushing is firmly seated against the asbestos
+packing by means of a brass screw gland which sets against a flange
+formed on the porcelain, and which screws into a thread at the upper
+portion of the plug body.
+
+The mica plug shown at B is somewhat simpler in construction than that
+shown at A. The mica core which keeps the central electrode separated
+from the steel body is composed of several layers of pure sheet mica
+wound around the steel rod longitudinally, and hundreds of stamped steel
+washers which are forced over this member and compacted under high
+pressure with some form of a binding material between them. Porcelain
+insulators are usually molded from high-grade clay and are approximately
+of the shapes desired by the designers of the plug. The central
+electrode may be held in place by mechanical means such as nuts,
+packings, and a shoulder on the rod, as shown at A. Another method
+sometimes used is to cement the electrode in place by means of some form
+of fire-clay cement. Whatever method of fastening is used, it is
+imperative that the joints be absolutely tight so that no gas can escape
+at the time of explosion. Porcelain is the material most widely used
+because it can be glazed so that it will not absorb oil, and it is
+subjected to such high temperature in baking that it is not liable to
+crack when heated.
+
+The spark-plugs may be screwed into any convenient part of the
+combustion chamber, the general practice being to install them in the
+caps over the inlet valves, or in the side of the combustion chamber, so
+the points will be directly in the path of the entering fresh gases from
+the carburetor.
+
+Other insulating materials sometimes used are glass, steatite (which is
+a form of soapstone) and lava. Mica and porcelain are the two common
+materials used because they give the best results. Glass is liable to
+crack, while lava or the soapstone insulating bushings absorb oil. The
+spark gap of the average plug is equal to about 1/32 of an inch for coil
+ignition and 1/40 of an inch when used in magneto circuits. A simple
+gauge for determining the gap setting is the thickness of an ordinary
+visiting card for magneto plugs, or a space equal to the thickness of a
+worn dime for a coil plug. The insulating bushings are made in a number
+of different ways, and while details of construction vary, spark-plugs
+do not differ essentially in design. The dimensions of the standardized
+plug recommended by the S. A. E. are shown at Fig. 73.
+
+[Illustration: Fig. 73.--Standard Airplane Engine Plug Suggested by S.
+A. E. Standards Committee.]
+
+It is often desirable to have a water-tight joint between the
+high-tension cable and the terminal screw on top of the insulating
+bushing of the spark-plug, especially in marine applications. The plug
+shown at C, Fig. 72, is provided with an insulating member or hood of
+porcelain, which is secured by a clip in such a manner that it makes a
+water-tight connection. Should the porcelain of a conventional form of
+plug become covered with water or dirty oil, the high-tension current is
+apt to run down this conducting material on the porcelain and reach the
+ground without having to complete its circuit by jumping the air gap and
+producing a spark. It will be evident that wherever a plug is exposed to
+the elements, which is often the case in airplane service, that it
+should be protected by an insulating hood which will keep the insulator
+dry and prevent short circuiting of the spark. The same end can be
+attained by slipping an ordinary rubber nipple over the porcelain
+insulator of any conventional plug and bringing up one end over the
+cable.
+
+
+TWO-SPARK IGNITION
+
+On most aviation engines, especially those having large cylinders, it is
+sometimes difficult to secure complete combustion by using a
+single-spark plug. If the combustion is not rapid the efficiency of the
+engine will be reduced proportionately. The compressed charge in the
+cylinder does not ignite all at once or instantaneously, as many assume,
+but it is the strata of gas nearest the plug which is ignited first.
+This in turn sets fire to consecutive layers of the charge until the
+entire mass is aflame. One may compare the combustion of gas in the
+gas-engine cylinder to the phenomenon which obtains when a heavy object
+is thrown into a pool of still water. First a small circle is seen at
+the point where the object has passed into the water, this circle in
+turn inducing other and larger circles until the whole surface of the
+pool has been agitated from the one central point. The method of
+igniting the gas is very similar, as the spark ignites the circle of gas
+immediately adjacent to the sparking point, and this circle in turn
+ignites a little larger one concentric with it. The second circle of
+flame sets fire to more of the gas, and finally the entire contents of
+the combustion chamber are burning.
+
+While ordinarily combustion is sufficiently rapid with a single plug so
+that the proper explosion is obtained at moderate engine speeds, if the
+engine is working fast and the cylinders are of large capacity more
+power may be obtained by setting fire to the mixture at two different
+points instead of but one. This may be accomplished by using two
+sparking-plugs in the cylinder instead of one, and experiments have
+shown that it is possible to gain from twenty-five to thirty per cent.
+in motor power at high speed with two-spark plugs, because the
+combustion of gas is accelerated by igniting the gas simultaneously in
+two places. The double-plug system on airplane engines is also a
+safeguard, as in event of failure of one plug in the cylinder the other
+would continue to fire the gas, and the engine will continue to function
+properly.
+
+In using magneto ignition some precautions are necessary relating to
+wiring and also the character of the spark-plugs employed. The conductor
+should be of good quality, have ample insulation, and be well protected
+from accumulations of oil, which would tend to decompose rubber
+insulation. It is customary to protect the wiring by running it through
+the conduits of fiber or metal tubing lined with insulating material.
+Multiple strand cables should be used for both primary and secondary
+wiring, and the insulation should be of rubber at least 3/16 inch thick.
+
+The spark-plugs commonly used for battery and coil ignition cannot
+always be employed when a magneto is fitted. The current produced by the
+mechanical generator has a greater amperage and more heat value than
+that obtained from transformer coils excited by battery current. The
+greater heat may burn or fuse the slender points used on some battery
+plugs and heavier electrodes are needed to resist the heating effect of
+the more intense arc. While the current has greater amperage it is not
+of as high potential or voltage as that commonly produced by the
+secondary winding of an induction coil, and it cannot overcome as much
+of a gap. Manufacturers of magneto plugs usually set the spark points
+about 1/64 of an inch apart. The most efficient magneto plug has a
+plurality of points so that when the distance between one set becomes
+too great the spark will take place between one of the other pairs of
+electrodes which are not separated by so great an air space.
+
+[Illustration: Fig. 74.--Special Mica Plug for Aviation Engines.]
+
+
+SPECIAL PLUGS FOR AIRPLANE WORK
+
+Airplane work calls for special construction of spark-plugs, owing to
+the high compression used in the engines and the fact that they are
+operated on open throttle practically all the time, thus causing a great
+deal of heat to be developed. The plug shown at Fig. 74 was recently
+described in "The Automobile," and has been devised especially for
+airplane engines and automobile racing power plants. The core C is built
+up of mica washers, and has square shoulders. As mica washers of
+different sizes may be used, and accurate machining, such as is
+necessary with conical clamping surfaces, is not required, the plug can
+be produced economically. The square shoulders of the core afford two
+gasket seats, and when the core is clamped in the shell by means of
+check nut E, it is accurately centered and a tight joint is formed. This
+construction also makes a shorter plug than where conical fits are used,
+thus improving the heat radiation through the stem. The lower end of the
+shell is provided with a baffle plate O, which tends to keep the oil
+away from the mica. There are perforations L in this baffle plate to
+prevent burnt gases being pocketed behind the baffle plate and
+pre-igniting the new charge. This construction also brings the firing
+point out into the firing chamber of the engine, and has all the other
+advantages of a closed-end plug. The stem P is made of brass or copper,
+on account of their superior heat conductivity, and the electrode J is
+swedged into the bottom of the stem, as shown at K, in a secure manner.
+
+The shell is finned, as shown at G, to provide greater heat radiating
+surface. There is also a fin F at the top of the stem, to increase the
+radiation of heat from the stem and electrode. The top of this finned
+portion is slightly countersunk, and the stem is riveted into same,
+thereby reducing the possibility of leakage past the threads on the
+stem. This finned portion is necked at A to take a slip terminal.
+
+In building up the core a small section of washers, I, is built up
+before the mica insulating tube D is placed on. This construction gives
+a better support to section I. Baffle plate O is bored out to allow the
+electrode J to pass through, and the clearance between baffle plate and
+electrode is made larger than the width of the gap between the firing
+points, so that there is no danger of the spark jumping from the
+electrode to the baffle plate.
+
+This plug will be furnished either with or without the finned portion,
+to meet individual requirements. The manufacturers lay special stress
+upon the simplicity of construction and upon the method of clamping,
+which is claimed to make the plug absolutely gas-tight.
+
+
+
+
+CHAPTER VII
+
+    Why Lubrication Is Necessary--Friction Defined--Theory of
+    Lubrication--Derivation of Lubricants--Properties of Cylinder
+    Oils--Factors Influencing Lubrication System Selection--Gnome
+    Type Engines Use Castor Oil--Hall-Scott Lubrication System--Oil
+    Supply by Constant Level Splash System--Dry Crank-Case System
+    Best for Airplane Engines--Why Cooling Systems Are Necessary--
+    Cooling Systems Generally Applied--Cooling by Positive Pump
+    Circulation--Thermo-Syphon System--Direct Air-Cooling Methods--
+    Air-Cooled Engine Design Considerations.
+
+
+WHY LUBRICATION IS NECESSARY
+
+The importance of minimizing friction at the various bearing surfaces of
+machines to secure mechanical efficiency is fully recognized by all
+mechanics, and proper lubricity of all parts of the mechanism is a very
+essential factor upon which the durability and successful operation of
+the motor car power plant depends. All of the moving members of the
+engine which are in contact with other portions, whether the motion is
+continuous or intermittent, of high or low velocity, or of rectilinear
+or continued rotary nature, should be provided with an adequate supply
+of oil. No other assemblage of mechanism is operated under conditions
+which are so much to its disadvantage as the motor car, and the tendency
+is toward a simplification of oiling methods so that the supply will be
+ample and automatically applied to the points needing it.
+
+In all machinery in motion the members which are in contact have a
+tendency to stick to each other, and the very minute projections which
+exist on even the smoothest of surfaces would have a tendency to cling
+or adhere to each other if the surfaces were not kept apart by some
+elastic and unctuous substance. This will flow or spread out over the
+surfaces and smooth out the inequalities existing which tend to produce
+heat and retard motion of the pieces relative to each other.
+
+A general impression which obtains is that well machined surfaces are
+smooth, but while they are apparently free from roughness, and no
+projections are visible to the naked eye, any smooth bearing surface,
+even if very carefully ground, will have a rough appearance if examined
+with a magnifying glass. An exaggerated condition to illustrate this
+point is shown at Fig. 75. The amount of friction will vary in
+proportion to the pressure on the surfaces in contact and will augment
+as the loads increase; the rougher surfaces will have more friction than
+smoother ones and soft bodies will produce more friction than hard
+substances.
+
+
+FRICTION DEFINED
+
+Friction is always present in any mechanism as a resisting force that
+tends to retard motion and bring all moving parts to a state of rest.
+The absorption of power by friction may be gauged by the amount of heat
+which exists at the bearing points. Friction of solids may be divided
+into two classes: sliding friction, such as exists between the piston
+and cylinder, or the bearings of a gas-engine, and rolling friction,
+which is that present when the load is supported by ball or roller
+bearings, or that which exists between the tires or the driving wheels
+and the road. Engineers endeavor to keep friction losses as low as
+possible, and much care is taken in all modern airplane engines to
+provide adequate methods of lubrication, or anti-friction bearings at
+all points where considerable friction exists.
+
+
+THEORY OF LUBRICATION
+
+The reason a lubricant is supplied to bearing points will be easily
+understood if one considers that these elastic substances flow between
+the close fitting surfaces, and by filling up the minute depressions in
+the surfaces and covering the high spots act as a cushion which absorbs
+the heat generated and takes the wear instead of the metallic bearing
+surface. The closer the parts fit together the more fluid the lubricant
+must be to pass between their surfaces, and at the same time it must
+possess sufficient body so that it will not be entirely forced out by
+the pressure existing between the parts.
+
+[Illustration: Fig. 75.--Showing Use of Magnifying Glass to Demonstrate
+that Apparently Smooth Metal Surfaces May Have Minute Irregularities
+which Produce Friction.]
+
+Oils should have good adhesive, as well as cohesive, qualities. The
+former are necessary so that the oil film will cling well to the
+surfaces of the bearings; the latter, so the oil particles will cling
+together and resist the tendency to separation which exists all the time
+the bearings are in operation. When used for gas-engine lubrication the
+oil should be capable of withstanding considerable heat in order that it
+will not be vaporized by the hot portions of the cylinder. It should
+have sufficient cold test so that it will remain fluid and flow readily
+at low temperature. Lubricants should be free from acid, or alkalies,
+which tend to produce a chemical action with metals and result in
+corrosion of the parts to which they are applied. It is imperative that
+the oil be exactly the proper quality and nature for the purpose
+intended and that it be applied in a positive manner. The requirements
+may be briefly summarized as follows:
+
+First--It must have sufficient body to prevent seizing of the parts to
+which it is applied and between which it is depended upon to maintain an
+elastic film, and yet it must not have too much viscosity, in order to
+minimize the internal or fluid friction which exists between the
+particles of the lubricant itself.
+
+Second--The lubricant must not coagulate or gum; must not injure the
+parts to which it is applied, either by chemical action or by producing
+injurious deposits, and it should not evaporate readily.
+
+Third--The character of the work will demand that the oil should not
+vaporize when heated or thicken to such a point that it will not flow
+readily when cold.
+
+Fourth--The oil must be free from acid, alkalies, animal or vegetable
+fillers, or other injurious agencies.
+
+Fifth--It must be carefully selected for the work required and should be
+a good conductor of heat.
+
+
+DERIVATION OF LUBRICANTS
+
+The first oils which were used for lubricating machinery were obtained
+from animal and vegetable sources, though at the present time most
+unguents are of mineral derivation. Lubricants may exist as fluids,
+semifluids, or solids. The viscosity will vary from light spindle or
+dynamo oils, which have but little more body than kerosene, to the
+heaviest greases and tallows. The most common solid employed as a
+lubricant is graphite, sometimes termed "plumbago" or "black lead." This
+substance is of mineral derivation.
+
+The disadvantage of oils of organic origin, such as those obtained from
+animal fats or vegetable substances, is that they will absorb oxygen
+from the atmosphere, which causes them to thicken or become rancid.
+Such oils have a very poor cold test, as they solidify at comparatively
+high temperatures, and their flashing point is so low that they cannot
+be used at points where much heat exists. In most animal oils various
+acids are present in greater or less quantities, and for this reason
+they are not well adapted for lubricating metallic surfaces which may be
+raised high enough in temperature to cause decomposition of the oils.
+
+Lubricants derived from the crude petroleum are called "Oleonaphthas"
+and they are a product of the process of refining petroleum through
+which gasoline and kerosene are obtained. They are of lower cost than
+vegetable or animal oil, and as they are of non-organic origin, they do
+not become rancid or gummy by constant exposure to the air, and they
+will have no corrosive action on metals because they contain no
+deleterious substances in chemical composition. By the process of
+fractional distillation mineral oils of all grades can be obtained. They
+have a lower cold and higher flash test and there is not the liability
+of spontaneous combustion that exists with animal oils.
+
+The organic oils are derived from fatty substances, which are present in
+the bodies of all animals and in some portions of plants. The general
+method of extracting oil from animal bodies is by a rendering process,
+which consists of applying sufficient heat to liquefy the oil and then
+separating it from the tissue with which it is combined by compression.
+The only oil which is used to any extent in gas-engine lubrication that
+is not of mineral derivation is castor oil. This substance has been used
+on high-speed racing automobile engines and on airplane power plants. It
+is obtained from the seeds of the castor plant, which contain a large
+percentage of oil.
+
+Among the solid substances which may be used for lubricating purposes
+may be mentioned tallow, which is obtained from the fat of animals, and
+graphite and soapstone, which are of mineral derivation. Tallow is
+never used at points where it will be exposed to much heat, though it
+is often employed as a filler for greases used in transmission gearing
+of autos. Graphite is sometimes mixed with oil and applied to cylinder
+lubrication, though it is most often used in connection with greases in
+the landing gear parts and for coating wires and cables of the airplane.
+Graphite is not affected by heat, cold, acids, or alkalies, and has a
+strong attraction for metal surfaces. It mixes readily with oils and
+greases and increases their efficiency in many applications. It is
+sometimes used where it would not be possible to use other lubricants
+because of extremes of temperature.
+
+The oils used for cylinder lubrication are obtained almost exclusively
+from crude petroleum derived from American wells. Special care must be
+taken in the selection of crude material, as every variety will not
+yield oil of the proper quality to be used as a cylinder lubricant. The
+crude petroleum is distilled as rapidly as possible with fire heat to
+vaporize off the naphthas and the burning oils. After these vapors have
+been given off superheated steam is provided to assist in distilling.
+When enough of the light elements have been eliminated the residue is
+drawn off, passed through a strainer to free it from grit and earthy
+matters, and is afterwards cooled to separate the wax from it. This is
+the dark cylinder oil and is the grade usually used for steam-engine
+cylinders.
+
+
+PROPERTIES OF CYLINDER OILS
+
+The oil that is to be used in the gasoline engine must be of high
+quality, and for that reason the best grades are distilled in a vacuum
+that the light distillates may be separated at much lower temperatures
+than ordinary conditions of distilling permit. If the degree of heat is
+not high the product is not so apt to decompose and deposit carbon. If
+it is desired to remove the color of the oil which is caused by free
+carbon and other impurities it can be accomplished by filtering the oil
+through charcoal. The greater the number of times the oil is filtered,
+the lighter it will become in color. The best cylinder oils have flash
+points usually in excess of 500 degrees F., and while they have a high
+degree of viscosity at 100 degrees F. they become more fluid as the
+temperature increases.
+
+The lubricating oils obtained by refining crude petroleum may be divided
+into three classes:
+
+First--The natural oils of great body which are prepared for use by
+allowing the crude material to settle in tanks at high temperature and
+from which the impurities are removed by natural filtration. These oils
+are given the necessary body and are free from the volatile substances
+they contain by means of superheated steam which provides a source of
+heat.
+
+Second--Another grade of these natural oils which are filtered again at
+high temperatures and under pressure through beds of animal charcoal to
+improve their color.
+
+Third--Pale, limpid oils, obtained by distillation and subsequent
+chemical treatment from the residuum produced in refining petroleum to
+obtain the fuel oils.
+
+Authorities agree that any form of mixed oil in which animal and mineral
+lubricants are combined should never be used in the cylinder of a gas
+engine as the admixture of the lubricants does not prevent the
+decomposition of the organic oil into the glycerides and fatty acids
+peculiar to the fat used. In a gas-engine cylinder the flame tends to
+produce more or less charring. The deposits of carbon will be much
+greater with animal oils than with those derived from the petroleum base
+because the constituents of a fat or tallow are not of the same volatile
+character as those which comprise the hydro-carbon oils which will
+evaporate or volatilize before they char in most instances.
+
+
+FACTORS INFLUENCING LUBRICATION SYSTEM SELECTION
+
+The suitability of oil for the proper and efficient lubrication of all
+internal combustion engines is determined chiefly by the following
+factors:
+
+1. Type of cooling system (operating temperatures).
+
+2. Type of lubricating system (method of applying oil to the moving
+parts).
+
+3. Rubbing speeds of contact surfaces.
+
+Were the operating temperatures, bearing surface speeds and lubrication
+systems identical, a single oil could be used in all engines with equal
+satisfaction. The only change then necessary in viscosity would be that
+due to climatic conditions. As engines are now designed, only three
+grades of oil are necessary for the lubrication of all types with the
+exception of Knight, air-cooled and some engines which run continuously
+at full load. In the specification of engine lubricants the feature of
+load carried by the engine should be carefully considered.
+
+_Full Load Engines._
+
+  1. Marine.
+  2. Racing automobile.
+  3. Aviation.
+  4. Farm tractor.
+  5. Some stationary.
+
+_Variable Load Engines._
+
+  1. Pleasure automobile.
+  2. Commercial vehicle.
+  3. Motor cycle.
+  4. Some stationary.
+
+Of the forms outlined, the only one we have any immediate concern about
+is the airplane power plant. The Platt & Washburn Refining Company, who
+have made a careful study of the lubrication problem as applied to all
+types of engines, have found a peculiar set of conditions to apply to
+oiling high-speed constant-duty or "full-load" engines. Modern airplane
+engines are designed to operate continuously at a fairly uniform high
+rotative speed and at full load over long periods of time. As a sequence
+to this heavy duty the operating temperatures are elevated. For the
+sake of extreme lightness in weight of all parts, very thin alloy steel
+aluminum or cast iron pistons are fitted and the temperature of the thin
+piston heads at the center reaches anywhere between 600 deg. and 1,400 deg.
+Fahr., as in automobile racing engines. Freely exposed to such intense
+heat hydro-carbon oils are partially "cracked" into light and heavy
+products or polymerized into solid hydro-carbons. From these facts it
+follows that only heavy mineral oils of low carbon residue and of the
+greatest chemical purity and stability should be used to secure good
+lubrication. In all cases the oil should be sufficiently heavy to assure
+the highest horse-power and fuel and oil economy compatible with perfect
+lubrication, avoiding, at the same time, carbonization and ignition
+failure. When aluminum pistons are used their superior heat-conducting
+properties aid materially in reducing the rate of oil destruction.
+
+The extraordinary evolutions described by airplanes in flight make it a
+matter of vital necessity to operate engines inclined at all angles to
+the vertical as well as in an upside-down position. To meet this
+situation lubricating systems have been elaborated so as to deliver an
+abundance of oil where needed and to eliminate possible flooding of
+cylinders. This is done by applying a full force feed system,
+distributing oil under considerable pressure to all working parts.
+Discharged through the bearings, the oil drains down to the suction side
+of a second pump located in the bottom of the base chamber. This pump
+being of greater capacity than the first prevents the accumulation of
+oil in the crank-case, and forces it to a separate oil reservoir-cooler,
+whence it flows back in rapid circulation to the pump feeding the
+bearings. With this arrangement positive lubrication is entirely
+independent of engine position. The lubricating system of the
+Thomas-Morse aviation engines, which is shown at Fig. 76, is typical of
+current practice.
+
+[Illustration: Fig. 76.--Pressure Feed Oiling System of Thomas Aviation
+Engine Includes Oil Cooling Means.]
+
+
+GNOME TYPE ENGINES USE CASTOR OIL
+
+The construction and operation of rotative radial cylinder engines
+introduce additional difficulties of lubrication to those already
+referred to and merit especial attention. Owing to the peculiar
+alimentation systems of Gnome type engines, atomized gasoline mixed with
+air is drawn through the hollow stationary crank-shaft directly into the
+crank-case which it fills on the way to the cylinders. Therein lies the
+trouble. Hydrocarbon oils are soon dissolved by the gasoline and washed
+off, leaving the bearing surfaces without adequate protection and
+exposed to instant wear and destruction. So castor oil is resorted to as
+an indispensable but unfortunate compromise. Of vegetable origin, it
+leaves a much more bulky carbon deposit in the explosion chambers than
+does mineral oil and its great affinity for oxygen causes the formation
+of voluminous gummy deposit in the crank-case. Engines employing it need
+to be dismounted and thoroughly scraped out at frequent intervals. It is
+advisable to use only unblended chemically pure castor oil in rotative
+engines, first by virtue of its insolubility in gasoline and second
+because its extra heavy body can resist the high temperature of
+air-cooled cylinders.
+
+
+HALL-SCOTT LUBRICATION SYSTEM
+
+[Illustration: Fig. 77.--Diagram of Oiling System, Hall-Scott Type A 125
+Horse-Power Engine.]
+
+The oiling system of the Hall-Scott type A-5 125 horse-power engine is
+clearly shown at Fig. 77. It is completely described in the instruction
+book issued by the company from which the following extracts are
+reproduced by permission. Crank-shaft, connecting rods and all other
+parts within the crank-case and cylinders are lubricated directly or
+indirectly by a force-feed oiling system. The cylinder walls and wrist
+pins are lubricated by oil spray thrown from the lower end of connecting
+rod bearings. This system is used only upon A-5 engines. Upon A-7a and
+A-5a engines a small tube supplies oil from connecting rod bearing
+directly upon the wrist pin. The oil is drawn from the strainer located
+at the lowest portion of the lower crank-case, forced around the main
+intake manifold oil jacket. From here it is circulated to the main
+distributing pipe located along the lower left hand side of upper
+crank-case. The oil is then forced directly to the lower side of
+crank-shaft, through holes drilled in each main bearing cup. Leakage
+from these main bearings is caught in scuppers placed upon the cheeks of
+the crank-shafts furnishing oil under pressure to the connecting rod
+bearings. A-7a and A-5a engines have small tubes leading from these
+bearings which convey the oil under pressure to the wrist pins.
+
+A bi-pass located at the front end of the distributing oil pipe can be
+regulated to lessen or raise the pressure. By screwing the valve in, the
+pressure will raise and more oil will be forced to the bearings. By
+unscrewing, pressure is reduced and less oil is fed. A-7a and A-5a
+engines have oil relief valves located just off of the main oil pump in
+the lower crank-case. This regulates the pressure at all times so that
+in cold weather there will be no danger of bursting oil pipes due to
+excessive pressure. If it is found the oil pressure is not maintained at
+a high enough level, inspect this valve. A stronger spring will not
+allow the oil to bi-pass so freely, and consequently the pressure will
+be raised; a weaker spring will bi-pass more oil and reduce the oil
+pressure materially. Independent of the above-mentioned system, a small,
+directly driven rotary oiler feeds oil to the base of each individual
+cylinder. The supply of oil is furnished by the main oil pump located in
+the lower crank-case. A small sight-feed regulator is furnished to
+control the supply of oil from this oiler. This instrument should be
+placed higher than the auxiliary oil distributor itself to enable the
+oil to drain by gravity feed to the oiler. If there is no available
+place with the necessary height in the front seat of plane, connect it
+directly to the intake L fitting on the oiler in an upright position. It
+should be regulated with full open throttle to maintain an oil level in
+the glass, approximately half way.
+
+An oil pressure gauge is provided. This should be run to the pilot's
+instrument board. The gauge registers the oil pressure upon the
+bearings, also determining its circulation. Strict watch should be
+maintained of this instrument by pilot, and if for any reason its hand
+should drop to 0 the motor should be immediately stopped and the trouble
+found before restarting engine. Care should be taken that the oil does
+not work up into the gauge, as it will prevent the correct gauge
+registering of oil pressure. The oil pressure will vary according to
+weather conditions and viscosity of oil used. In normal weather, with
+the engine properly warmed up, the pressure will register on the oil
+gauge from 5 to 10 pounds when the engine is turning from 1,275 to 1,300
+r. p. m. This does not apply to all aviation engines, however, as the
+proper pressure advised for the Curtiss OX-2 motor is from 40 to 55
+pounds at the gauge.
+
+The oil sump plug is located at the lowest point of the lower
+crank-case. This is a combination dirt, water and sediment trap. It is
+easily removed by unscrewing. Oil is furnished mechanically to the
+cam-shaft housing under pressure through a small tube leading from the
+main distributing pipe at the propeller end of engine directly into the
+end of cam-shaft housing. The opposite end of this housing is amply
+relieved to allow the oil to rapidly flow down upon cam-shaft, magneto,
+pinion-shaft, and crank-shaft gears, after which it returns to lower
+crank-case. An outside overflow pipe is also provided to carry away the
+surplus oil.
+
+
+DRAINING OIL FROM CRANK-CASE
+
+The oil strainer is placed at the lowest point of the lower crank-case.
+This strainer should be removed after every five to eight hours running
+of the engine and cleaned thoroughly with gasoline. It is also advisable
+to squirt distillate up into the case through the opening where the
+strainer has been removed. Allow this distillate to drain out thoroughly
+before replacing the plug with strainer attached. Be sure gasket is in
+place on plug before replacing. Pour new oil in through either of the
+two breather pipes on exhaust side of motor. Be sure to replace strainer
+screens if removed. If, through oversight, the engine does not receive
+sufficient lubrication and begins to heat or pound, it should be stopped
+immediately. After allowing engine to cool pour at least three gallons
+of oil into oil sump. Fill radiator with water after engine has cooled.
+Should there be apparent damage, the engine should be thoroughly
+inspected immediately without further running. If no obvious damage has
+been done, the engine should be given a careful examination at the
+earliest opportunity to see that the running without oil has not burned
+the bearings or caused other trouble.
+
+Oils best adapted for Hall-Scott engines have the following properties:
+A flash test of not less than 400 deg. F.; viscosity of not less than 75
+to 85 taken at 21 deg. F. with Saybolt's Universal Viscosimeter.
+
+_Zeroline heavy duty oil_, manufactured by the Standard Oil Company of
+California; also,
+
+_Gargoyle mobile B oil_, manufactured by the Vacuum Oil Company, both
+fulfill the above specifications. One or the other of these oils can be
+obtained all over the world.
+
+Monogram extra heavy is also recommended.
+
+
+OIL SUPPLY BY CONSTANT LEVEL SPLASH SYSTEM
+
+The splash system of lubrication that depends on the connecting rod to
+distribute the lubricant is one of the most successful and simplest
+forms for simple four- and six-cylinder vertical automobile engines, but
+is not as well adapted to the oiling of airplane power plants for
+reasons previously stated. If too much oil is supplied the surplus will
+work past the piston rings and into the combustion chamber, where it
+will burn and cause carbon deposits. Too much oil will also cause an
+engine to smoke and an excess of lubricating oil is usually manifested
+by a bluish-white smoke issuing from the exhaust.
+
+A good method of maintaining a constant level of oil for the successful
+application of the splash system is shown at Fig. 78. The engine base
+casting includes a separate chamber which serves as an oil container and
+which is below the level of oil in the crank-case. The lubricant is
+drawn from the sump or oil container by means of a positive oil pump
+which discharges directly into the engine case. The level is maintained
+by an overflow pipe which allows all excess lubricant to flow back into
+the oil container at the bottom of the cylinder. Before passing into the
+pump again the oil is strained or filtered by a screen of wire gauze and
+all foreign matter removed. Owing to the rapid circulation of the oil it
+may be used over and over again for quite a period of time. The oil is
+introduced directly into the crank-case by a breather pipe and the level
+is indicated by a rod carried by a float which rises when the container
+is replenished and falls when the available supply diminishes. It will
+be noted that with such system the only apparatus required besides the
+oil tank which is cast integral with the bottom of the crank-case is a
+suitable pump to maintain circulation of oil. This member is always
+positively driven, either by means of shaft and universal coupling or
+direct gearing. As the system is entirely automatic in action, it will
+furnish a positive supply of oil at all desired points, and it cannot be
+tampered with by the inexpert because no adjustments are provided or
+needed.
+
+
+DRY CRANK-CASE SYSTEM BEST FOR AIRPLANE ENGINES
+
+[Illustration: Fig. 78.--Sectional View of Typical Motor Showing Parts
+Needing Lubrication and Method of Applying Oil by Constant Level Splash
+System. Note also Water Jacket and Spaces for Water Circulation.]
+
+In most airplane power plants it is considered desirable to supply the
+oil directly to the parts needing it by suitable leads instead of
+depending solely upon the distributing action of scoops on the
+connecting rod big ends. A system of this nature is shown at Fig. 77.
+The oil is carried in the crank-case, as is common practice, but the
+normal oil level is below the point where it will be reached by the
+connecting rod. It is drawn from the crank-case by a plunger pump which
+directs it to a manifold leading directly to conductors which supply the
+main journals. After the oil has been used on these points it drains
+back into the bottom of the crank-case. An excess is provided which is
+supplied to the connecting rod ends by passages drilled into the webs of
+the crank-shaft and part way into the crank-pins as shown by the dotted
+lines. The oil which is present at the connecting rod crank-pins is
+thrown off by centrifugal force and lubricates the cylinder walls and
+other internal parts. Regulating screws are provided so that the amount
+of oil supplied the different points may be regulated at will. A relief
+check valve is installed to take care of excess lubricant and to allow
+any oil that does not pass back into the pipe line to overflow or
+bi-pass into the main container.
+
+[Illustration: Fig. 79.--Pressure Feed Oil-Supply System of Airplane
+Power Plants has Many Good Features.]
+
+A simple system of this nature is shown graphically in a phantom view of
+the crank-case at Fig. 79, in which the oil passages are made specially
+prominent. The oil is taken from a reservoir at the bottom of the engine
+base by the usual form of gear oil pump and is supplied to a main feed
+manifold which extends the length of the crank-case. Individual
+conductors lead to the five main bearings, which in turn supply the
+crank-pins by passages drilled through the crank-shaft web. In this
+power plant the connecting rods are hollow section bronze castings and
+the passage through the center of the connecting rod serves to convey
+the lubricant from the crank-pins to the wrist-pins. The cylinder walls
+are oiled by the spray of lubricant thrown off the revolving crank-shaft
+by centrifugal force. Oil projection by the dippers on the connecting
+rod ends from constant level troughs is unequal upon the cylinder walls
+of the two-cylinder blocks of an eight- or twelve-cylinder V engine.
+This gives rise, on one side of the engine, to under-lubrication, and,
+on the other side, to over-lubrication, as shown at Fig. 80, A. This
+applies to all modifications of splash lubricating systems.
+
+When a force-feed lubricating system is used, the oil, escaping past the
+cheeks of both ends of the crank-pin bearings, is thrown off at a
+tangent to the crank-pin circle in all directions, supplying the
+cylinders on both sides with an equal quantity of oil, as at Fig. 80, B.
+
+
+WHY COOLING SYSTEMS ARE NECESSARY
+
+The reader should understand from preceding chapters that the power of
+an internal-combustion motor is obtained by the rapid combustion and
+consequent expansion of some inflammable gas. The operation in brief is
+that when air or any other gas or vapor is heated, it will expand and
+that if this gas is confined in a space which will not permit expansion,
+pressure will be exerted against all sides of the containing chamber.
+The more a gas is heated, the more pressure it will exert upon the walls
+of the combustion chamber it confines. Pressure in a gas may be
+created by increasing its temperature and inversely heat may be created
+by pressure. When a gas is compressed its total volume is reduced and
+the temperature is augmented.
+
+[Illustration: Fig. 80.--Why Pressure Feed System is Best for
+Eight-Cylinder Vee Airplane Engines.]
+
+The efficiency of any form of heat engine is determined by the power
+obtained from a certain fuel consumption. A definite amount of energy
+will be liberated in the form of heat when a pound of any fuel is
+burned. The efficiency of any heat engine is proportional to the power
+developed from a definite quantity of fuel with the least loss of
+thermal units. If the greater proportion of the heat units derived by
+burning the explosive mixture could be utilized in doing useful work,
+the efficiency of the gasoline engine would be greater than that of any
+other form of energizing power. There is a great loss of heat from
+various causes, among which can be cited the reduction of pressure
+through cooling the motor and the loss of heat through the exhaust
+valves when the burned gases are expelled from the cylinder.
+
+The loss through the water jacket of the average automobile power plant
+is over 50 per cent. of the total fuel efficiency. This means that more
+than half of the heat units available for power are absorbed and
+dissipated by the cooling water. Another 16 per cent. is lost through
+the exhaust valve, and but 33-1/3 per cent. of the heat units do useful
+work. The great loss of heat through the cooling systems cannot be
+avoided, as some method must be provided to keep the temperature of the
+engine within proper bounds. It is apparent that the rapid combustion
+and continued series of explosions would soon heat the metal portions of
+the engine to a red heat if some means were not taken to conduct much of
+this heat away. The high temperature of the parts would burn the
+lubricating oil, even that of the best quality, and the piston and rings
+would expand to such a degree, especially when deprived of oil, that
+they would seize in the cylinder. This would score the walls, and the
+friction which ensued would tend to bind the parts so tightly that the
+piston would stick, bearings would be burned out, the valves would warp,
+and the engine would soon become inoperative.
+
+[Illustration: Fig. 81.--Operating Temperatures of Automobile Engine
+Parts Useful as a Guide to Understand Airplane Power Plant Heat.]
+
+The best temperature to secure efficient operation is one on which
+considerable difference of opinion exists among engineers. The fact that
+the efficiency of an engine is dependent upon the ratio of heat
+converted into useful work compared to that generated by the explosion
+of the gas is an accepted fact. It is very important that the engine
+should not get too hot, and on the other hand it is equally vital that
+the cylinders be not robbed of too much heat. The object of cylinder
+cooling is to keep the temperature of the cylinder below the danger
+point, but at the same time to have it as high as possible to secure
+maximum power from the gas burned. The usual operating temperatures of
+an automobile engine are shown at Fig. 81, and this can be taken as an
+approximation of the temperatures apt to exist in an airplane engine of
+conventional design as well when at ground level or not very high in the
+air. The newer very high compression airplane engines in which
+compressions of eight or nine atmospheres are used, or about 125 pounds
+per square inch, will run considerably hotter than the temperatures
+indicated.
+
+
+COOLING SYSTEMS GENERALLY APPLIED
+
+There are two general systems of engine cooling in common use, that in
+which water is heated by the absorption of heat from the engine and then
+cooled by air, and the other method in which the air is directed onto
+the cylinder and absorbs the heat directly instead of through the medium
+of water. When the liquid is employed in cooling it is circulated
+through jackets which surround the cylinder casting and the water may be
+kept in motion by two methods. The one generally favored is to use a
+positive circulating pump of some form which is driven by the engine to
+keep the water in motion. The other system is to utilize a natural
+principle that heated water is lighter than cold liquid and that it will
+tend to rise to the top of the cylinder when it becomes heated to the
+proper temperature and cooled water takes its place at the bottom of the
+water jacket.
+
+Air-cooling methods may be by radiation or convection. In the former
+case the effective outer surface of the cylinder is increased by the
+addition of flanges machined or cast thereon, and the air is depended on
+to rise from the cylinder as heated and be replaced by cooler air. This,
+of course, is found only on stationary engines. When a positive air
+draught is directed against the cylinder by means of the propeller slip
+stream in an airplane, cooling is by convection and radiation both.
+Sometimes the air draught may be directed against the cylinder walls by
+some form of jacket which confines it to the heated portions of the
+cylinder.
+
+
+COOLING BY POSITIVE WATER CIRCULATION
+
+[Illustration: Fig. 82.--Water Cooling of Salmson Seven-Cylinder Radial
+Airplane Engine.]
+
+A typical water-cooling system in which a pump is depended upon to
+promote circulation of the cooling liquid is shown at Figs. 82 and 83.
+The radiator is carried at the front end of the fuselage in most cases,
+and serves as a combined water tank and cooler, but in some cases it is
+carried at the side of the engine, as in Fig. 84, or attached to the
+central portion of the aerofoil or wing structure. It is composed of an
+upper and lower portion joined together by a series of pipes which may
+be round and provided with a series of fins to radiate the heat, or
+which may be flat in order to have the water pass through in thin sheets
+and cool it more easily. Cellular or honeycomb coolers are composed of a
+large number of bent tubes which will expose a large area of surface to
+the cooling influence of the air draught forced through the radiator
+either by the forward movement of the vehicle or by some type of fan.
+The cellular and flat tube types have almost entirely displaced the
+flange tube radiators which were formerly popular because they cool the
+water more effectively, and may be made lighter than the tubular
+radiator could be for engines of the same capacity.
+
+[Illustration: Fig. 83.--How Water Cooling System of Thomas Airplane
+Engine is Installed in Fuselage.]
+
+The water is drawn from the lower header of the radiator by the pump and
+is forced through a manifold to the lower portion of the water jackets
+of the cylinder. It becomes heated as it passes around the cylinder
+walls and combustion chambers and the hot water passes out of the top of
+the water jacket to the upper portion of the radiator. Here it is
+divided in thin streams and directed against comparatively cool metal
+which abstracts the heat from the water. As it becomes cooler it falls
+to the bottom of the radiator because its weight increases as the
+temperature becomes lower. By the time it reaches the lower tank of the
+radiator it has been cooled sufficiently so that it may be again passed
+around the cylinders of the motor. The popular form of circulating pump
+is known as the "centrifugal type" because a rotary impeller of
+paddle-wheel form throws water which it receives at a central point
+toward the outside and thus causes it to maintain a definite rate of
+circulation. The pump is always a separate appliance attached to the
+engine and driven by positive gearing or direct-shaft connection. The
+centrifugal pump is not as positive as the gear form, and some
+manufacturers prefer the latter because of the positive pumping
+features. They are very simple in form, consisting of a suitable cast
+body in which a pair of spur pinions having large teeth are carried. One
+of these gears is driven by suitable means, and as it turns the other
+member they maintain a flow of water around the pump body. The pump
+should always be installed in series with the water pipe which conveys
+the cool liquid from the lower compartment of the radiator to the
+coolest portion of the water jacket.
+
+[Illustration: Fig. 84.--Finned Tube Radiators at the Side of Hall-Scott
+Airplane Power Plant Installed in Standard Fuselage.]
+
+
+WATER CIRCULATION BY NATURAL SYSTEM
+
+Some automobile engineers contend that the rapid water circulation
+obtained by using a pump may cool the cylinders too much, and that the
+temperature of the engine may be reduced so much that the efficiency
+will be lessened. For this reason there is a growing tendency to use the
+natural method of water circulation as the cooling liquid is supplied to
+the cylinder jackets just below the boiling point and the water issues
+from the jacket at the top of the cylinder after it has absorbed
+sufficient heat to raise it just about to the boiling point.
+
+As the water becomes heated by contact with the hot cylinder and
+combustion-chamber walls it rises to the top of the water jacket, flows
+to the cooler, where enough of the heat is absorbed to cause it to
+become sensibly greater in weight. As the water becomes cooler, it falls
+to the bottom of the radiator and it is again supplied to the water
+jacket. The circulation is entirely automatic and continues as long as
+there is a difference in temperature between the liquid in the water
+spaces of the engine and that in the cooler. The circulation becomes
+brisker as the engine becomes hotter and thus the temperature of the
+cylinders is kept more nearly to a fixed point. With the thermosyphon
+system the cooling liquid is nearly always at its boiling point, whereas
+if the circulation is maintained by a pump the engine will become cooler
+at high speed and will heat up more at low speed.
+
+With the thermosyphon, or natural system of cooling, more water must be
+carried than with the pump-maintained circulation methods. The water
+spaces around the cylinders should be larger, the inlet and discharge
+water manifolds should have greater capacity, and be free from sharp
+corners which might impede the flow. The radiator must also carry more
+water than the form used in connection with the pump because of the
+brisker pump circulation which maintains the engine temperature at a
+lower point. Consideration of the above will show why the pump system is
+almost universally used in connection with airplane power plant cooling.
+
+
+DIRECT AIR-COOLING METHODS
+
+The earliest known method of cooling the cylinder of gas-engines was by
+means of a current of air passed through a jacket which confined it
+close to the cylinder walls and was used by Daimler on his first
+gas-engine. The gasoline engine of that time was not as efficient as the
+later form, and other conditions which materialized made it desirable to
+cool the engine by water. Even as gasoline engines became more and more
+perfected there has always existed a prejudice against air cooling,
+though many forms of engines have been used, both in automobile and
+aircraft applications where the air-cooling method has proven to be very
+practical.
+
+The simplest system of air cooling is that in which the cylinders are
+provided with a series of flanges which increase the effective radiating
+surface of the cylinder and directing an air-current from a fan against
+the flanges to absorb the heat. This increase in the available radiating
+surface of an air-cooled cylinder is necessary because air does not
+absorb heat as readily as water and therefore more surface must be
+provided that the excess heat be absorbed sufficiently fast to prevent
+distortion of the cylinders. Air-cooling systems are based on a law
+formulated by Newton, which is: "The rate for cooling for a body in a
+uniform current of air is directly proportional to the speed of the air
+current and the amount of radiating surface exposed to the cooling
+effect."
+
+
+AIR-COOLED ENGINE DESIGN CONSIDERATIONS
+
+[Illustration: Fig. 85.--Anzani Testing His Five-Cylinder Air Cooled
+Aviation Motor Installed in Bleriot Monoplane. Note Exposure of Flanged
+Cylinders to Propeller Slip Stream.]
+
+There are certain considerations which must be taken into account in
+designing an air-cooled engine, which are often overlooked in those
+forms cooled by water. Large valves must be provided to insure rapid
+expulsion of the flaming exhaust gas and also to admit promptly the
+fresh cool mixture from the carburetor. The valves of air-cooled engines
+are usually placed in the cylinder-head, in order to eliminate any
+pockets or sharp passages which would impede the flow of gas or retain
+some of the products of combustion and their heat. When high power is
+desired multiple-cylinder engines should be used, as there is a certain
+limit to the size of a successful air-cooled cylinder. Much better
+results are secured from those having small cubical contents because the
+heat from small quantities of gas will be more quickly carried off than
+from greater amounts. All successful engines of the aviation type which
+have been air-cooled have been of the multiple-cylinder type.
+
+An air-cooled engine must be placed in the fuselage, as at Fig. 85, in
+such a way that there will be a positive circulation of air around it
+all the time that it is in operation. The air current may be produced by
+the tractor screw at the front end of the motor, or by a suction or
+blower fan attached to the crank-shaft as in the Renault engine or by
+rotating the cylinders as in the Le Rhone and Gnome motors. Greater care
+is required in lubrication of the air-cooled cylinders and only the best
+quality of oil should be used to insure satisfactory oiling.
+
+The combustion chambers must be proportioned so that distribution of
+metal is as uniform as possible in order to prevent uneven expansion
+during increase in temperature and uneven contraction when the cylinder
+is cooled. It is essential that the inside walls of the combustion
+chamber be as smooth as possible because any sharp angle or projection
+may absorb sufficient heat to remain incandescent and cause trouble by
+igniting the mixture before the proper time. The best grades of cast
+iron or steel should be used in the cylinder and piston and the machine
+work must be done very accurately so the piston will operate with
+minimum friction in the cylinder. The cylinder bore should not exceed
+4-1/2 or 5 inches and the compression pressure should never exceed 75
+pounds absolute, or about five atmospheres, or serious overheating will
+result.
+
+As an example of the care taken in disposing of the exhaust gases in
+order to obtain practical air-cooling, some cylinders are provided with
+a series of auxiliary exhaust ports uncovered by the piston when it
+reaches the end of its power stroke. The auxiliary exhaust ports open
+just as soon as the full force of the explosion has been spent and a
+portion of the flaming gases is discharged through the ports in the
+bottom of the cylinder. Less of the exhaust gases remains to be
+discharged through the regular exhaust member in the cylinder-head and
+this will not heat the walls of the cylinder nearly as much as the
+larger quantity of hot gas would. That the auxiliary exhaust port is of
+considerable value is conceded by many designers of fixed and fan-shaped
+air-cooled motors for airplanes.
+
+Among the advantages stated for direct air cooling, the greatest is the
+elimination of cooling water and its cooling auxiliaries, which is a
+factor of some moment, as it permits considerable reduction in
+horse-power-weight ratio of the engine, something very much to be
+desired. In the temperate zone, where the majority of airplanes are
+used, the weather conditions change in a very few months from the warm
+summer to the extreme cold winter, and when water-cooled systems are
+employed it is necessary to add some chemical substance to the water to
+prevent it from freezing. The substances commonly employed are
+glycerine, wood alcohol, or a saturated solution of calcium chloride.
+Alcohol has the disadvantage in that it vaporizes readily and must be
+often renewed. Glycerine affects the rubber hose, while the calcium
+chloride solution crystallizes and deposits salt in the radiator and
+water pipes.
+
+One of the disadvantages of an air-cooling method, as stated by those
+who do not favor this system, is that engines cooled by air cannot be
+operated for extended periods under constant load or at very high speed
+without heating up to such a point that premature ignition of the charge
+may result. The water-cooling systems, at the other hand, maintain the
+temperature of the engine more nearly constant than is possible with an
+air-cooled motor, and an engine cooled by water can be operated under
+conditions of inferior lubrication or poor mixture adjustment that would
+seriously interfere with proper and efficient cooling by air.
+
+Air-cooled motors, as a rule, use less fuel than water-cooled engines,
+because the higher temperature of the cylinder does not permit of a full
+charge of gas being inspired on the intake stroke. As special care is
+needed in operating an air-cooled engine to obtain satisfactory results
+and because of the greater difficulty which obtains in providing proper
+lubrication and fuel mixtures which will not produce undue heating, the
+air-cooled system has but few adherents at the present time, and
+practically all airplanes, with but very few exceptions, are provided
+with water-cooled power plants. Those fitted with air-cooled engines are
+usually short-flight types where maximum lightness is desired in order
+to obtain high speed and quick climb. The water-cooled engines are best
+suited for airplanes intended for long flights. The Gnome, Le Rhone and
+Clerget engines are thoroughly practical and have been widely used in
+France and England. These are rotary radial cylinder types. The Anzani
+is a fixed cylinder engine used on training machines, while the Renault
+is a V-type engine made in eight- and twelve-cylinder V forms that has
+been used on reconnaissance and bombing airplanes with success. These
+types will be fully considered in proper sequence.
+
+
+
+
+CHAPTER VIII
+
+    Methods of Cylinder Construction--Block Castings--Influence on
+    Crank-Shaft Design--Combustion Chamber Design--Bore and Stroke
+    Ratio--Meaning of Piston Speed--Advantage of Off-Set Cylinders--
+    Valve Location of Vital Import--Valve Installation Practice--
+    Valve Design and Construction--Valve Operation--Methods of
+    Driving Cam-Shaft--Valve Springs--Valve Timing--Blowing Back--
+    Lead Given Exhaust Valve--Exhaust Closing, Inlet Opening--
+    Closing the Inlet Valve--Time of Ignition--How an Engine Is
+    Timed--Gnome "Monosoupape" Valve Timing--Springless Valves--Four
+    Valves per Cylinder.
+
+
+The improvements noted in the modern internal combustion motors have
+been due to many conditions. The continual experimenting by leading
+mechanical minds could have but one ultimate result. The parts of the
+engines have been lightened and strengthened, and greater power has been
+obtained without increasing piston displacement. A careful study has
+been made of the many conditions which make for efficient motor action,
+and that the main principles are well recognized by all engineers is
+well shown by the standardization of design noted in modern power
+plants. There are many different methods of applying the same principle,
+and it will be the purpose of this chapter to define the ways in which
+the construction may be changed and still achieve the same results. The
+various components may exist in many different forms, and all have their
+advantages and disadvantages. That all methods are practical is best
+shown by the large number of successful engines which use radically
+different designs.
+
+
+METHODS OF CYLINDER CONSTRUCTION
+
+One of the most important parts of the gasoline engine and one that has
+material bearing upon its efficiency is the cylinder unit. The cylinders
+may be cast individually, or in pairs, and it is possible to make all
+cylinders a unit or block casting. Some typical methods of cylinder
+construction are shown in accompanying illustrations. The appearance of
+individual cylinder castings may be ascertained by examination of the
+Hall-Scott airplane engine. Air-cooled engine cylinders are always of
+the individual pattern.
+
+Considered from a purely theoretical point of view, the individual
+cylinder casting has much in its favor. It is advanced that more uniform
+cooling is possible than where the cylinders are cast either in pairs or
+three or four in one casting. More uniform cooling insures that the
+expansion or change of form due to heating will be more equal. This is
+an important condition because the cylinder bore must remain true under
+all conditions of operation. If the heating effect is not uniform, which
+condition is liable to obtain if metal is not evenly distributed, the
+cylinder may become distorted by heat and the bore be out of truth. When
+separate cylinders are used it is possible to make a uniform water space
+and have the cooling liquid evenly distributed around the cylinder. In
+multiple cylinder castings this is not always the rule, as in many
+instances, especially in four-cylinder block motors where compactness is
+the main feature, there is but little space between the cylinders for
+the passage of water. Under such circumstances the cooling effect is not
+even, and the stresses which obtain because of unequal expansion may
+distort the cylinder to some extent. When steel cylinders are made from
+forgings, the water jackets are usually of copper or sheet steel
+attached to the forging by autogenous welding; in the case of the latter
+and, in some cases, the former may be electro-deposited on the
+cylinders.
+
+
+BLOCK CASTINGS
+
+[Illustration: Fig. 86.--Views of Four-Cylinder Duesenberg Airplane
+Engine Cylinder Block.]
+
+The advantage of casting the cylinders in blocks is that a motor may be
+much shorter than it would be if individual castings were used. It is
+admitted that when the cylinders are cast together a more compact,
+rigid, and stronger power plant is obtained than when cast separately.
+There is a disadvantage, however, in that if one cylinder becomes
+damaged it will be necessary to replace the entire unit, which means
+scrapping three good cylinders because one of the four has failed. When
+the cylinders are cast separately one need only replace the one that has
+become damaged. The casting of four cylinders in one unit is made
+possible by improved foundry methods, and when proper provision is made
+for holding the cores when the metal is poured and the cylinder casts
+are good, the construction is one of distinct merit. It is sometimes the
+case that the proportion of sound castings is less when cylinders are
+cast in block, but if the proper precautions are observed in molding and
+the proper mixtures of cast iron used, the ratio of defective castings
+is no more than when cylinders are molded individually. As an example of
+the courage of engineers in departing from old-established rules, the
+cylinder casting shown at Fig. 86 may be considered typical. This is
+used on the Duesenberg four-cylinder sixteen-valve 4-3/4" x 7" engine
+which has a piston displacement of 496 cu. in. At a speed of 2,000
+r.p.m., corresponding to a piston speed of 2,325 ft. per min., the
+engine is guaranteed to develop 125 horse-power. The weight of the model
+engine without gear reduction is 436 lbs., but a number of refinements
+have been made in the design whereby it is expected to get the weight
+down to 390 lbs. The four cylinders are cast from semi-steel in a single
+block, with integral heads. The cylinder construction is the same as
+that which has always been used by Mr. Duesenberg, inlet and exhaust
+valves being arranged horizontally opposite each other in the head.
+There are large openings in the water jacket at both sides and at the
+ends, which are closed by means of aluminum covers, water-tightness
+being secured by the use of gaskets. This results in a saving in weight
+because the aluminum covers can be made considerably lighter than it
+would be possible to cast the jacket walls, and, besides, it permits of
+obtaining a more nearly uniform thickness of cylinder wall, as the cores
+can be much better supported. The cooling water passes completely around
+each cylinder, and there is a very considerable space between the two
+central cylinders, this being made necessary in order to get the large
+bearing area desirable for the central bearing.
+
+It is common practice to cast the water jackets integral with the
+cylinders, if cast iron or aluminum is used, and this is also the most
+economical method of applying it because it gives good results in
+practice. An important detail is that the water spaces must be
+proportioned so that they are equal around the cylinders whether these
+members are cast individually, in pairs, threes or fours. When cylinders
+are cast in block form it is good practice to leave a large opening in
+the jacket wall which will assist in supporting the core and make for
+uniform water space. It will be noticed that the casting shown at Fig.
+86 has a large opening in the side of the cylinder block. These openings
+are closed after the interior of the casting is thoroughly cleaned of
+all sand, core wire, etc., by brass, cast iron or aluminum plates. These
+also have particular value in that they may be removed after the motor
+has been in use, thus permitting one to clean out the interior of the
+water jacket and dispose of the rust, sediment, and incrustation which
+are always present after the engine has been in active service for a
+time.
+
+Among the advantages claimed for the practice of casting cylinders in
+blocks may be mentioned compactness, lightness, rigidity, simplicity of
+water piping, as well as permitting the use of simple forms of inlet and
+exhaust manifolds. The light weight is not only due to the reduction of
+the cylinder mass but because the block construction permits one to
+lighten the entire motor. The fact that all cylinders are cast together
+decreases vibration, and as the construction is very rigid, disalignment
+of working parts is practically eliminated. When inlet and exhaust
+manifolds are cored in the block casting, as is sometimes the case, but
+one joint is needed on each of these instead of the multiplicity of
+joints which obtain when the cylinders are individual castings. The
+water piping is also simplified. In the case of a four-cylinder block
+motor but two pipes are used; one for the water to enter the cylinder
+jacket, the other for the cooling liquid to discharge through.
+
+
+INFLUENCE ON CRANK-SHAFT DESIGN
+
+[Illustration: Fig. 87.--Twin-Cylinder Block of Sturtevant Airplane
+Engine is Cast of Aluminum, and Has Removable Cylinder Head.]
+
+The method of casting the cylinders has a material influence on the
+design of the crank-shaft as will be shown in proper sequence. When four
+cylinders are combined in one block it is possible to use a two-bearing
+crank-shaft. Where cylinders are cast in pairs a three-bearing
+crank-shaft is commonly supplied, and when cylinders are cast as
+individual units it is thought necessary to supply a five-bearing
+crank-shaft, though sometimes shafts having but three journals are used
+successfully. Obviously the shafts must be stronger and stiffer to
+withstand the stresses imposed if two supporting bearings are used than
+if a larger number are employed. In this connection it may be stated
+that there is less difficulty in securing alignment with a lesser number
+of bearings and there is also less friction. On the other hand, the
+greater the number of points of support a crank-shaft has the lighter
+the webs can be made and still have requisite strength.
+
+
+COMBUSTION CHAMBER DESIGN
+
+[Illustration: Fig. 88.--Aluminum Cylinder Pair Casting of Thomas 150
+Horse-Power Airplane Engine is of the L Head Type.]
+
+Another point of importance in the design of the cylinder, and one which
+has considerable influence upon the power developed, is the shape of the
+combustion chamber. The endeavor of designers is to obtain maximum power
+from a cylinder of certain proportions, and the greater energy obtained
+without increasing piston displacement or fuel consumption the higher
+the efficiency of the motor. To prevent troubles due to pre-ignition it
+is necessary that the combustion chamber be made so that there will be
+no roughness, sharp corners, or edges of metal which may remain
+incandescent when heated or which will serve to collect carbon deposits
+by providing a point of anchorage. With the object of providing an
+absolutely clean combustion chamber some makers use a separable head
+unit to their twin cylinder castings, such as shown at Fig. 87 and Fig.
+88. These permit one to machine the entire interior of the cylinder and
+combustion chamber. The relation of valve location and combustion
+chamber design will be considered in proper sequence. These cylinders
+are cast of aluminum, instead of cast iron, as is customary, and are
+provided with steel or cast iron cylinder liners forced in the soft
+metal casting bores.
+
+
+BORE AND STROKE RATIO
+
+A question that has been a vexed one and which has been the subject of
+considerable controversy is the proper proportion of the bore to the
+stroke. The early gas engines had a certain well-defined bore to stroke
+ratio, as it was usual at that time to make the stroke twice as long as
+the bore was wide, but this cannot be done when high speed is desired.
+With the development of the present-day motor the stroke or piston
+travel has been gradually shortened so that the relative proportions of
+bore and stroke have become nearly equal. Of late there seems to be a
+tendency among designers to return to the proportions which formerly
+obtained, and the stroke is sometimes one and a half or one and
+three-quarter times the bore.
+
+Engines designed for high speed should have the stroke not much longer
+than the diameter of the bore. The disadvantage of short-stroke engines
+is that they will not pull well at low speeds, though they run with
+great regularity and smoothness at high velocity. The long-stroke engine
+is much superior for slow speed work, and it will pull steadily and with
+increasing power at low speed. It was formerly thought that such engines
+should never turn more than a moderate number of revolutions, in order
+not to exceed the safe piston speed of 1,000 feet per minute. This old
+theory or rule of practice has been discarded in designing high
+efficiency automobile racing and aviation engines, and piston speeds
+from 2,500 to 3,000 feet per minute are sometimes used, though the
+average is around 2,000 feet per minute. While both short- and
+long-stroke motors have their advantages, it would seem desirable to
+average between the two. That is why a proportion of four to five or six
+seems to be more general than that of four to seven or eight, which
+would be a long-stroke ratio. Careful analysis of a number of foreign
+aviation motors shows that the average stroke is about 1.2 times the
+bore dimensions, though some instances were noted where it was as high
+as 1.7 times the bore.
+
+
+MEANING OF PISTON SPEED
+
+The factor which limits the stroke and makes the speed of rotation so
+dependent upon the travel of the piston is piston speed. Lubrication is
+the main factor which determines piston speed, and the higher the rate
+of piston travel the greater care must be taken to insure proper oiling.
+Let us fully consider what is meant by piston speed.
+
+Assume that a motor has a piston travel or stroke of six inches, for the
+sake of illustration. It would take two strokes of the piston to cover
+one foot, or twelve inches, and as there are two strokes to a revolution
+it will be seen that this permits of a normal speed of 1,000 revolutions
+per minute for an engine with a six-inch stroke, if one does not exceed
+1,000 feet per minute. If the stroke was only four inches, a normal
+speed of 1,500 revolutions per minute would be possible without
+exceeding the prescribed limit. The crank-shaft of a small engine,
+having three-inch stroke, could turn at a speed of 2,000 revolutions per
+minute without danger of exceeding the safe speed limit. It will be seen
+that the longer the stroke the slower the speed of the engine, if one
+desires to keep the piston speed within the bounds as recommended, but
+modern practice allows of greatly exceeding the speeds formerly thought
+best.
+
+
+ADVANTAGES OF OFF-SET CYLINDERS
+
+[Illustration: Fig. 90.--Cross Section of Austro-Daimler Engine, Showing
+Offset Cylinder Construction. Note Applied Water Jacket and Peculiar
+Valve Action.]
+
+Another point upon which considerable difference of opinion exists
+relates to the method of placing the cylinder upon the crank-case--i.e.,
+whether its center line should be placed directly over the center of the
+crank-shaft, or to one side of center. The motor shown at Fig. 90 is an
+off-set type, in that the center line of the cylinder is a little to
+one side of the center of the crank-shaft. Diagrams are presented at
+Fig. 91 which show the advantages of off-set crank-shaft construction.
+The view at A is a section through a simple motor with the conventional
+cylinder placing, the center line of both crank-shaft and cylinder
+coinciding. The view at B shows the cylinder placed to one side of
+center so that its center line is distinct from that of the crank-shaft
+and at some distance from it. The amount of off-set allowed is a point
+of contention, the usual amount being from fifteen to twenty-five per
+cent. of the stroke. The advantages of the off-set are shown at Fig. 91,
+C. If the crank turns in direction of the arrow there is a certain
+resistance to motion which is proportional to the amount of energy
+exerted by the engine and the resistance offered by the load. There are
+two thrusts acting against the cylinder wall to be considered, that due
+to explosion or expansion of the gas, and that which resists the motion
+of the piston. These thrusts may be represented by arrows, one which
+acts directly in a vertical direction on the piston top, the other
+along a straight line through the center of the connecting rod. Between
+these two thrusts one can draw a line representing a resultant force
+which serves to bring the piston in forcible contact with one side of
+the cylinder wall, this being known as side thrust. As shown at C, the
+crank-shaft is at 90 degrees, or about one-half stroke, and the
+connecting rod is at 20 degrees angle. The shorter connecting rod would
+increase the diagonal resultant and side thrusts, while a longer one
+would reduce the angle of the connecting rod and the side thrust of the
+piston would be less. With the off-set construction, as shown at D, it
+will be noticed that with the same connecting-rod length as shown at C
+and with the crank-shaft at 90 degrees of the circle that the
+connecting-rod angle is 14 degrees and the side thrust is reduced
+proportionately.
+
+[Illustration: Fig. 91.--Diagrams Demonstrating Advantages of Offset
+Crank-Shaft Construction.]
+
+Another important advantage is that greater efficiency is obtained from
+the explosion with an off-set crank-shaft, because the crank is already
+inclined when the piston is at top center, and all the energy imparted
+to the piston by the burning mixture can be exerted directly into
+producing a useful turning effort. When a cylinder is placed directly on
+a line with the crank-shaft, as shown at A, it will be evident that some
+of the force produced by the expansion of the gas will be exerted in a
+direct line and until the crank moves the crank throw and connecting rod
+are practically a solid member. The pressure which might be employed in
+obtaining useful turning effort is wasted by causing a direct pressure
+upon the lower half of the main bearing and the upper half of the
+crank-pin bushing.
+
+Very good and easily understood illustrations showing advantages of the
+off-set construction are shown at E and F. This is a bicycle
+crank-hanger. It is advanced that the effort of the rider is not as well
+applied when the crank is at position E as when it is at position F.
+Position E corresponds to the position of the parts when the cylinder is
+placed directly over the crank-shaft center. Position F may be compared
+to the condition which is present when the off-set cylinder construction
+is used.
+
+
+VALVE LOCATION OF VITAL IMPORT
+
+It has often been said that a chain is no stronger than its weakest
+link, and this is as true of the explosive motor as it is of any other
+piece of mechanism. Many motors which appeared to be excellently
+designed and which were well constructed did not prove satisfactory
+because some minor detail or part had not been properly considered by
+the designer. A factor having material bearing upon the efficiency of
+the internal combustion motor is the location of the valves and the
+shape of the combustion chamber which is largely influenced by their
+placing. The fundamental consideration of valve design is that the gases
+be admitted and discharged from the cylinder as quickly as possible in
+order that the speed of gas flow will not be impeded and produce back
+pressure. This is imperative in obtaining satisfactory operation in any
+form of motor. If the inlet passages are constricted the cylinder will
+not fill with explosive mixture promptly, whereas if the exhaust gases
+are not fully expelled the parts of the inert products of combustion
+retained dilute the fresh charge, making it slow burning and causing
+lost power and overheating. When an engine employs water as a cooling
+medium this substance will absorb the surplus heat readily, and the
+effects of overheating are not noticed as quickly as when air-cooled
+cylinders are employed. Valve sizes have a decided bearing upon the
+speed of motors and some valve locations permit the use of larger
+members than do other positions.
+
+While piston velocity is an important factor in determinations of power
+output, it must be considered from the aspect of the wear produced upon
+the various parts of the motor. It is evident that engines which run
+very fast, especially of high power, must be under a greater strain than
+those operating at lower speeds. The valve-operating mechanism is
+especially susceptible to the influence of rapid movement, and the
+slower the engine the longer the parts will wear and the more reliable
+the valve action.
+
+[Illustration: Fig. 92.--Diagram Showing Forms of Cylinder Demanded by
+Different Valve Placings. A--T Head Type, Valves on Opposite Sides. B--L
+Head Cylinder, Valves Side by Side. C--L Head Cylinder, One Valve in
+Head, Other in Pocket. D--Inlet Valve Over Exhaust Member, Both in Side
+Pocket. E--Valve-in-the-Head Type with Vertical Valves. F--Inclined
+Valves Placed to Open Directly into Combustion Chamber.]
+
+As will be seen by reference to the accompanying illustration, Fig. 92,
+there are many ways in which valves may be placed in the cylinder. Each
+method outlined possesses some point of advantage, because all of the
+types illustrated are used by reputable automobile manufacturers. The
+method outlined at Fig. 92, A, is widely used, and because of its shape
+the cylinder is known as the "T" form. It is approved for automobile use
+for several reasons, the most important being that large valves can be
+employed and a well-balanced and symmetrical cylinder casting obtained.
+Two independent cam-shafts are needed, one operating the inlet valves,
+the other the exhaust members. The valve-operating mechanism can be very
+simple in form, consisting of a plunger actuated by the cam which
+transmits the cam motion to the valve-stem, raising the valve as the cam
+follower rides on the point of the cam. Piping may be placed without
+crowding, and larger manifolds can be fitted than in some other
+constructions. This has special value, as it permits the use of an
+adequate discharge pipe on the exhaust side with its obvious advantages.
+This method of cylinder construction is never found on airplane engines
+because it does not permit of maximum power output.
+
+On the other hand, if considered from a viewpoint of actual heat
+efficiency, it is theoretically the worst form of combustion chamber.
+This disadvantage is probably compensated for by uniformity of expansion
+of the cylinder because of balanced design. The ignition spark-plug may
+be located directly over the inlet valve in the path of the incoming
+fresh gases, and both valves may be easily removed and inspected by
+unscrewing the valve caps without taking off the manifolds.
+
+The valve installation shown at C is somewhat unusual, though it
+provides for the use of valves of large diameter. Easy charging is
+insured because of the large inlet valve directly in the top of the
+cylinder. Conditions may be reversed if necessary, and the gases
+discharged through this large valve. Both methods are used, though it
+would seem that the free exhaust provided by allowing the gases to
+escape directly from the combustion chamber through the overhead valve
+to the exhaust manifold would make for more power. The method outlined
+at Fig. 92, F and at Fig. 90 is one that has been widely employed on
+large automobile racing motors where extreme power is required, as well
+as in engines constructed for aviation service. The inclination of the
+valves permits the use of large valves, and these open directly into the
+combustion chamber. There are no pockets to retain heat or dead gas, and
+free intake and outlet of gas is obtained. This form is quite
+satisfactory from a theoretical point of view because of the almost
+ideal combustion chamber form. Some difficulty is experienced, however,
+in properly water-jacketing the valve chamber which experience has shown
+to be necessary if the engine is to have high power.
+
+The motor shown at Fig. 92, B and Fig. 88 employs cylinders of the "L"
+type. Both valves are placed in a common extension from the combustion
+chamber, and being located side by side both are actuated from a common
+cam-shaft. The inlet and exhaust pipes may be placed on the same side of
+the engine and a very compact assemblage is obtained, though this is
+optional if passages are cored in the cylinder pairs to lead the gases
+to opposite sides. The valves may be easily removed if desired, and the
+construction is fairly good from the viewpoint of both foundry man and
+machinist. The chief disadvantage is the limited area of the valves and
+the loss of heat efficiency due to the pocket. This form of combustion
+chamber, however, is more efficient than the "T" head construction,
+though with the latter the use of larger valves probably compensates for
+the greater heat loss. It has been stated as an advantage of this
+construction that both manifolds can be placed at the same side of the
+engine and a compact assembly secured. On the other hand, the
+disadvantage may be cited that in order to put both pipes on the same
+side they must be of smaller size than can be used when the valves are
+oppositely placed. The "L" form cylinder is sometimes made more
+efficient if but one valve is placed in the pocket while the other is
+placed over it. This construction is well shown at Fig. 92, D and is
+found on Anzani motors.
+
+[Illustration: Fig. 93.--Sectional View of Engine Cylinder Showing Valve
+and Cage Installation.]
+
+The method of valve application shown at Fig. 87 is an ingenious method
+of overcoming some of the disadvantages inherent with valve-in-the-head
+motors. In the first place it is possible to water-jacket the valves
+thoroughly, which is difficult to accomplish when they are mounted in
+cages. The water circulates directly around the walls of the valve
+chambers, which is superior to a construction where separate cages are
+used, as there are two thicknesses of metal with the latter, that of the
+valve-cage proper and the wall of the cylinder. The cooling medium is in
+contact only with the outer wall, and as there is always a loss of heat
+conductivity at a joint it is practically impossible to keep the
+exhaust valves and their seats at a uniform temperature. The valves may
+be of larger size without the use of pockets when seating directly in
+the head. In fact, they could be equal in diameter to almost half the
+bore of the cylinder, which provides an ideal condition of charge
+placement and exhaust. When valve grinding is necessary the entire head
+is easily removed by taking off six nuts and loosening inlet manifold
+connections, which operation would be necessary even if cages were
+employed, as in the engine shown at Fig. 93.
+
+[Illustration: Fig. 94.--Diagrams Showing How Gas Enters Cylinder
+Through Overhead Valves and Other Types. A--Tee Head Cylinder. B--L Head
+Cylinder. C--Overhead Valve.]
+
+[Illustration: Fig. 95.--Conventional Methods of Operating Internal
+Combustion Motor Valves.]
+
+At Fig. 94, A and B, a section through a typical "L"-shaped cylinder is
+depicted. It will be evident that where a pocket construction is
+employed, in addition to its faculty for absorbing heat, the passage of
+gas would be impeded. For example, the inlet gas rushing in through the
+open valve would impinge sharply upon the valve-cap or combustion head
+directly over the valve and then must turn at a sharp angle to enter the
+combustion chamber and then at another sharp angle to fill the
+cylinders. The same conditions apply to the exhaust gases, though they
+are reversed. When the valve-in-the-head type of cylinder is employed,
+as at C, the only resistance offered the gas is in the manifold. As far
+as the passage of the gases in and out of the cylinder is concerned,
+ideal conditions obtain. It is claimed that valve-in-the-head motors are
+more flexible and responsive than other forms, but the construction has
+the disadvantage in that the valves must be opened through a rather
+complicated system of push rods and rocker arms instead of the simpler
+and direct plunger which can be used with either the "T" or "L" head
+cylinders. This is clearly outlined in the illustrations at Fig. 95,
+where A shows the valve in the head-operating mechanism necessary if the
+cam-shaft is carried at the cylinder base, while B shows the most direct
+push-rod action obtained with "T" or "L" head cylinder placing.
+
+[Illustration: Fig. 96.--Examples of Direct Valve Actuation by Overhead
+Cam-Shaft. A--Mercedes. B--Hall-Scott. C--Wisconsin.]
+
+[Illustration: Fig. 97.
+
+CENSORED]
+
+[Illustration: Fig. 98.
+
+CENSORED]
+
+The objection can be easily met by carrying the cam-shaft above the
+cylinders and driving it by means of gearing. The types of engine
+cylinders using this construction are shown at Fig. 96, and it will be
+evident that a positive and direct valve action is possible by following
+the construction originated by the Mercedes (German) aviation engine
+designers and outlined at A. The other forms at B and C are very clearly
+adaptations of this design. The Hall-Scott engine at Fig. 97 is depicted
+in part section and no trouble will be experienced in understanding the
+bevel pinion and gear drive from the crank-shaft to the overhead
+cam-shaft through a vertical counter-shaft. A very direct valve action
+is used in the Duesenberg engines, one of which is shown in part section
+at Fig. 98. The valves are parallel with the piston top and are actuated
+by rocker arms, one end of which bears against the valve stem, and the
+other rides the cam-shaft.
+
+[Illustration: Fig. 99.--Sectional Views Showing Arrangement of Novel
+Concentric Valve Arrangement Devised by Panhard for Aerial Engines.]
+
+The form shown at Fig. 99 shows an ingenious application of the
+valve-in-the-head idea which permits one to obtain large valves. It has
+been used on some of the Panhard aviation engines and on the American
+Aeromarine power plants. The inlet passage is controlled by the sliding
+sleeve which is hollow and slotted so as to permit the inlet gases to
+enter the cylinder through the regular type poppet valve which seats in
+the exhaust sleeve. When the exhaust valve is operated by the tappet rod
+and rocker arm the intake valve is also carried down with it. The
+intake gas passage is closed, however, and the burned gases are
+discharged through the large annular passage surrounding the sleeve.
+When the inlet valve leaves its seat in the sleeve the passage of cool
+gas around the sleeve keeps the temperature of both valves to a low
+point and the danger of warping is minimized. A dome-shaped combustion
+chamber may be used, which is an ideal form in conserving heat
+efficiency, and as large valves may be installed the flow of both fresh
+and exhaust gases may be obtained with minimum resistance. The intake
+valve is opened by a small auxiliary rocker arm which is lifted when the
+cam follower rides into the depression in the cam by the action of the
+strong spring around the push rod. When the cam follower rides on the
+high point the exhaust sleeve is depressed from its seat against the
+cylinder. By using a cam having both positive and negative profiles, a
+single rod suffices for both valves because of its push and pull action.
+
+
+VALVE DESIGN AND CONSTRUCTION
+
+Valve dimensions are an important detail to be considered and can be
+determined by several conditions, among which may be cited method of
+installation, operating mechanism, material employed, engine speed
+desired, manner of cylinder cooling and degree of lift desired. A review
+of various methods of valve location has shown that when the valves are
+placed directly in the head we can obtain the ideal cylinder form,
+though larger valves may be used if housed in a separate pocket, as
+afforded by the "T" head construction. The method of operation has much
+to do with the size of the valves. For example, if an automatic inlet
+valve is employed it is good practice to limit the lift and obtain the
+required area of port opening by augmenting the diameter. Because of
+this a valve of the automatic type is usually made twenty per cent.
+larger than one mechanically operated. When both are actuated by cam
+mechanism, as is now common practice, they are usually made the same
+size and are interchangeable, which greatly simplifies manufacture. The
+relation of valve diameter to cylinder bore is one that has been
+discussed for some time by engineers. The writer's experience would
+indicate that they should be at least half the bore, if possible. While
+the mushroom type or poppet valve has become standard and is the most
+widely used form at the present time, there is some difference of
+opinion among designers as to the materials employed and the angle of
+the seat. Most valves have a bevel seat, though some have a flat
+seating. The flat seat valve has the distinctive advantage of providing
+a clear opening with lesser lift, this conducing to free gas flow. It
+also has value because it is silent in operation, but the disadvantage
+is present that best material and workmanship must be used in their
+construction to obtain satisfactory results. As it can be made very
+light it is particularly well adapted for use as an automatic inlet
+valve. Among other disadvantages cited is the claim that it is more
+susceptible to derangement, owing to the particles of foreign matter
+getting under the seat. With a bevel seat it is argued that the foreign
+matter would be more easily dislodged by the gas flow, and that the
+valve would close tighter because it is drawn positively against the
+bevel seat.
+
+Several methods of valve construction are the vogue, the most popular
+form being the one-piece type; those which are composed of a head of one
+material and stem of another are seldom used in airplane engines because
+they are not reliable. In the built-up construction the head is usually
+of high nickel steel or cast iron, which metals possess good
+heat-resisting qualities. Heads made of these materials are not likely
+to warp, scale, or pit, as is sometimes the case when ordinary grades of
+machinery steel are used. The cast-iron head construction is not popular
+because it is often difficult to keep the head tight on the stem. There
+is a slight difference in expansion ratio between the head and the stem,
+and as the stem is either screwed or riveted to the cast-iron head the
+constant hammering of the valve against its seat may loosen the joint.
+As soon as the head is loose on the stem the action of the valve becomes
+erratic. The best practice is to machine the valves from tungsten steel
+forgings. This material has splendid heat-resisting qualities and will
+not pit or become scored easily. Even the electrically welded head to
+stem types which are used in automobile engines are not looked upon with
+favor in the aviation engine. Valve stem guides and valve stems must be
+machined very accurately to insure correct action. The usual practice in
+automobile engines is shown at Fig. 100.
+
+[Illustration: Fig. 100.--Showing Clearance Allowed Between Valve Stem
+and Valve Stem Guide to Secure Free Action.]
+
+
+VALVE OPERATION
+
+The methods of valve operation commonly used vary according to the type
+of cylinder construction employed. In all cases the valves are lifted
+from their seats by cam-actuated mechanism. Various forms of
+valve-lifting cams are shown at Fig. 101. As will be seen, a cam
+consists of a circle to which a raised, approximately triangular member
+has been added at one point. When the cam follower rides on the circle,
+as shown at Fig. 102, there is no difference in height between the cam
+center and its periphery and there is no movement of the plunger. As
+soon as the raised portion of the cam strikes the plunger it will lift
+it, and this reciprocating movement is transmitted to the valve stem by
+suitable mechanical connections.
+
+[Illustration: Fig. 101.--Forms of Valve-Lifting Cams Generally
+Employed. A--Cam Profile for Long Dwell and Quick Lift. B--Typical Inlet
+Cam Used with Mushroom Type Follower. C--Average Form of Cam.
+D--Designed to Give Quick Lift and Gradual Closing.]
+
+The cam forms outlined at Fig. 101 are those commonly used. That at A is
+used on engines where it is desired to obtain a quick lift and to keep
+the valve fully opened as long as possible. It is a noisy form, however,
+and is not very widely employed. That at B is utilized more often as an
+inlet cam while the profile shown at C is generally depended on to
+operate exhaust valves. The cam shown at D is a composite form which has
+some of the features of the other three types. It will give the quick
+opening of form A, the gradual closing of form B, and the time of
+maximum valve opening provided by cam profile C.
+
+[Illustration: Fig. 102.--Showing Principal Types of Cam Followers which
+Have Received General Application.]
+
+The various types of valve plungers used are shown at Fig. 102. That
+shown at A is the simplest form, consisting of a simple cylindrical
+member having a rounded end which follows the cam profile. These are
+sometimes made of square stock or kept from rotating by means of a key
+or pin. A line contact is possible when the plunger is kept from
+turning, whereas but a single point bearing is obtained when the plunger
+is cylindrical and free to revolve. The plunger shown at A will follow
+only cam profiles which have gradual lifts. The plunger shown at B is
+left free to revolve in the guide bushing and is provided with a flat
+mushroom head which serves as a cam follower. The type shown at C
+carries a roller at its lower end and may follow very irregular cam
+profiles if abrupt lifts are desired. While forms A and B are the
+simplest, that outlined at C in its various forms is more widely used.
+Compound plungers are used on the Curtiss OX-2 motors, one inside the
+other. The small or inner one works on a cam of conventional design, the
+outer plunger follows a profile having a flat spot to permit of a pull
+rod action instead of a push rod action. All the methods in which levers
+are used to operate valves are more or less noisy because clearance must
+be left between the valve stem and the stop of the plunger. The space
+must be taken up before the valve will leave its seat, and when the
+engine is operated at high speeds the forcible contact between the
+plunger and valve stem produces a rattling sound until the valves become
+heated and expand and the stems lengthen out. Clearance must be left
+between the valve stems and actuating means. This clearance is clearly
+shown in Fig. 103 and should be .020" (twenty thousandths) when engine
+is cold. The amount of clearance allowed depends entirely upon the
+design of the engine and length of valve stem. On the Curtiss OX-2
+engines the clearance is but .010" (ten thousandths) because the valve
+stems are shorter. Too little clearance will result in loss of power or
+misfiring when engine is hot. Too much clearance will not allow the
+valve to open its full amount and will disturb the timing.
+
+[Illustration: Fig. 103.--Diagram Showing Proper Clearance to Allow
+Between Adjusting Screw and Valve Stems in Hall-Scott Aviation Engines.]
+
+
+METHODS OF DRIVING CAM-SHAFT
+
+Two systems of cam-shaft operation are used. The most common of these is
+by means of gearing of some form. If the cam-shaft is at right angles to
+the crank-shaft it may be driven by worm, spiral, or bevel gearing. If
+the cam-shaft is parallel to the crank-shaft, simple spur gear or chain
+connection may be used to turn it. A typical cam-shaft for an
+eight-cylinder V engine is shown at Fig. 104. It will be seen that the
+sixteen cams are forged integrally with the shaft and that it is
+spur-gear driven. The cam-shaft drive of the Hall-Scott motor is shown
+at Fig. 97.
+
+[Illustration: Fig. 104.--Cam-Shaft of Thomas Airplane Motor Has Cams
+Forged Integral. Note Split Cam-Shaft Bearings and Method of Gear
+Retention.]
+
+While gearing is more commonly used, considerable attention has been
+directed of late to silent chains for cam-shaft operation. The ordinary
+forms of block or roller chain have not proven successful in this
+application, but the silent chain, which is in reality a link belt
+operating over toothed pulleys, has demonstrated its worth. The tendency
+to its use is more noted on foreign motors than those of American
+design. It first came to public notice when employed on the
+Daimler-Knight engine for driving the small auxiliary crank-shafts which
+reciprocated the sleeve valves. The advantages cited for the application
+of chains are, first, silent operation, which obtains even after the
+chains have worn considerably; second, in designing it is not necessary
+to figure on maintaining certain absolute center distances between the
+crank-shaft and cam-shaft sprockets, as would be the case if
+conventional forms of gearing were used. On some forms of motor
+employing gears, three and even four members are needed to turn the
+cam-shaft. With a chain drive but two sprockets are necessary, the chain
+forming a flexible connection which permits the driving and driven
+members to be placed at any distance apart that the exigencies of the
+design demand. When chains are used it is advised that some means for
+compensating chain slack be provided, or the valve timing will lag when
+chains are worn. Many combination drives may be worked out with chains
+that would not be possible with other forms of gearing. Direct gear
+drive is favored at the present time by airplane engine designers
+because they are the most certain and positive means, even when a number
+of gears must be used as intermediate drive members. With overhead
+cam-shafts, bevel gears work out very well in practice, as in the
+Hall-Scott motors and others of that type.
+
+
+VALVE SPRINGS
+
+[Illustration: Fig. 105.--Section Through Cylinder of Knight Motor,
+Showing Important Parts of Valve Motion.]
+
+Another consideration of importance is the use of proper valve-springs,
+and particular care should be taken with those, of automatic valves. The
+spring must be weak enough to allow the valve to open when the suction
+is light, and must be of sufficient strength to close it in time at high
+speeds. It should be made as large as possible in diameter and with a
+large number of convolutions, in order that fatigue of the metal be
+obviated, and it is imperative that all springs be of the same strength
+when used on a multiple-cylinder engine. Practically all valves used to
+control the gas flow in airplane engines are mechanically operated. On
+the exhaust valve the spring must be strong enough so that the valve
+will not be sucked in on the inlet stroke. It should be borne in mind
+that if the spring is too strong a strain will be imposed on the
+valve-operating mechanism, and a hammering action produced which may
+cause deformation of the valve-seat. Only pressure enough to insure that
+the operating mechanism will follow the cam is required. It is common
+practice to make the inlet and exhaust valve springs of the same
+tension when the valves are of the same size and both mechanically
+operated. This is done merely to simplify manufacture and not because it
+is necessary for the inlet valve-spring to be as strong as the other.
+Valve springs of the helical coil type are generally used, though
+torsion or "scissors" springs and laminated or single-leaf springs are
+also utilized in special applications. Two springs are used on each
+valve in some valve-in-the-head types; a spring of small pitch diameter
+inside the regular valve-spring and concentric with it. Its function is
+to keep the valve from falling into the cylinder in event of breakage of
+the main spring in some cases, and to provide a stronger return action
+in others.
+
+[Illustration: Fig. 106.--Diagrams Showing Knight Sleeve Valve Action.]
+
+
+KNIGHT SLIDE VALVE MOTOR
+
+The sectional view through the cylinder at Fig. 105 shows the Knight
+sliding sleeves and their actuating means very clearly. The diagrams at
+Fig. 106 show graphically the sleeve movements and their relation to the
+crank-shaft and piston travel. The action may be summed up as follows:
+The inlet port begins to open when the lower edge of the opening of the
+outside sleeve which is moving down passes the top of the slot in the
+inner member also moving downwardly. The inlet port is closed when the
+lower edge of the slot in the inner sleeve which is moving up passes the
+top edge of the port in the outer sleeve which is also moving toward the
+top of the cylinder. The inlet opening extends over two hundred degrees
+of crank motion. The exhaust port is uncovered slightly when the lower
+edge of the port in the inner sleeve which is moving down passes the
+lower edge of the portion of the cylinder head which protrudes in the
+cylinder. When the top of the port in the outer sleeve traveling toward
+the bottom of the cylinder passes the lower edge of the slot in the
+cylinder wall the exhaust passage is closed. The exhaust opening extends
+over a period corresponding to about two hundred and forty degrees of
+crank motion. The Knight motor has not been applied to aircraft to the
+writer's knowledge, but an eight-cylinder Vee design that might be
+useful in that connection if lightened is shown at Fig. 107. The main
+object is to show that the Knight valve action is the only other besides
+the mushroom or poppet valve that has been applied successfully to high
+speed gasoline engines.
+
+
+VALVE TIMING
+
+It is in valve timing that the greatest difference of opinion prevails
+among engineers, and it is rare that one will see the same formula in
+different motors. It is true that the same timing could not be used with
+motors of different construction, as there are many factors which
+determine the amount of lead to be given to the valves. The most
+important of these is the relative size of the valve to the cylinder
+bore, the speed of rotation it is desired to obtain, the fuel
+efficiency, the location of the valves, and other factors too numerous
+to mention.
+
+[Illustration: Fig. 107.--Cross Sectional View of Knight Type Eight
+Cylinder V Engine.]
+
+Most of the readers should be familiar with the cycle of operation of
+the internal combustion motor of the four-stroke type, and it seems
+unnecessary to go into detail except to present a review. The first
+stroke of the piston is one in which a charge of gas is taken into the
+motor; the second stroke, which is in reverse direction to the first, is
+a compression stroke, at the end of which the spark takes place,
+exploding the charge and driving the piston down on the third or
+expansion stroke, which is in the same direction as the intake stroke,
+and finally, after the piston has nearly reached the end of this stroke,
+another valve opens to allow the burned gases to escape, and remains
+open until the piston has reached the end of the fourth stroke and is in
+a position to begin the series over again. The ends of the strokes are
+reached when the piston comes to a stop at either top or bottom of the
+cylinder and reverses its motion. That point is known as a center, and
+there are two for each cylinder, top and bottom centers, respectively.
+
+All circles may be divided into 360 parts, each of which is known as a
+degree, and, in turn, each of these degrees may be again divided into
+minutes and seconds, though we need not concern ourselves with anything
+less than the degree. Each stroke of the piston represents 180 degrees
+travel of the crank, because two strokes represent one complete
+revolution of three hundred and sixty degrees. The top and bottom
+centers are therefore separated by 180 degrees. Theoretically each phase
+of a four-cycle engine begins and ends at a center, though in actual
+practice the inertia or movement of the gases makes it necessary to
+allow a lead or lag to the valve, as the case may be. If a valve opens
+before a center, the distance is called "lead"; if it closes after a
+center, this distance is known as "lag." The profile of the cams
+ordinarily used to open or close the valves represents a considerable
+time in relation to the 180 degrees of the crank-shaft travel, and the
+area of the passages through which the gases are admitted or exhausted
+is quite small owing to the necessity of having to open or close the
+valves at stated times; therefore, to open an adequately large passage
+for the gases it is necessary to open the valves earlier and close them
+later than at centers.
+
+That advancing the opening of the exhaust valve was of value was
+discovered on the early motors and is explained by the necessity of
+releasing a large amount of gas, the volume of which has been greatly
+raised by the heat of combustion. When the inlet valves were
+mechanically operated it was found that allowing them to lag at closing
+enabled the inspiration of a greater volume of gas. Disregarding the
+inertia or flow of the gases, opening the exhaust at center would enable
+one to obtain full value of the expanding gases the entire length of the
+piston stroke, and it would not be necessary to keep the valve open
+after the top center, as the reverse stroke would produce a suction
+effect which might draw some of the inert charge back into the cylinder.
+On the other hand, giving full consideration to the inertia of the gas,
+opening the valve before center is reached will provide for quick
+expulsion of the gases, which have sufficient velocity at the end of the
+stroke, so that if the valve is allowed to remain open a little longer,
+the amount of lag varying with the opinions of the designer, the
+cylinder is cleared in a more thorough manner.
+
+
+BLOWING BACK
+
+When the factor of retarded opening is considered without reckoning the
+inertia of the gases, it would appear that if the valve were allowed to
+remain open after center had passed, say, on the closing of the inlet,
+the piston, having reversed its motion, would have the effect of
+expelling part of the fresh charge through the still open valve as it
+passed inward at its compression stroke. This effect is called blowing
+back, and is often noted with motors where the valve settings are not
+absolutely correct, or where the valve-springs or seats are defective
+and prevent proper closing.
+
+This factor is not of as much import as might appear, as on closer
+consideration it will be seen that the movement of the piston as the
+crank reaches either end of the stroke is less per degree of angular
+movement than it is when the angle of the connecting rod is greater.
+Then, again, a certain length of time is required for the reversal of
+motion of the piston, during which time the crank is in motion but the
+piston practically at a standstill. If the valves are allowed to remain
+open during this period, the passage of the gas in or out of the
+cylinder will be by its own momentum.
+
+
+LEAD GIVEN EXHAUST VALVE
+
+The faster a motor turns, all other things being equal, the greater the
+amount of lead or advance it is necessary to give the opening of the
+exhaust valve. It is self-evident truth that if the speed of a motor is
+doubled it travels twice as many degrees in the time necessary to lower
+the pressure. As most designers are cognizant of this fact, the valves
+are proportioned accordingly. It is well to consider in this respect
+that the cam profile has much to do with the manner in which the valve
+is opened; that is, the lift may be abrupt and the gas allowed to escape
+in a body, or the opening may be gradual, the gas issuing from the
+cylinder in thin streams. An analogy may be made with the opening of any
+bottle which contains liquid highly carbonated. If the cork is removed
+suddenly the gas escapes with a loud pop, but, on the other hand, if the
+bottle is uncorked gradually, the gas escapes from the receptacle in
+thin streams around the cork, and passage of the gases to the air is
+accomplished without noise. While the second plan is not harsh, it is
+slower than the former, as must be evident.
+
+
+EXHAUST CLOSING, INLET OPENING
+
+A point which has been much discussed by engineers is the proper
+relation of the closing of the exhaust valve and the opening of the
+inlet. Theoretically they should succeed each other, the exhaust closing
+at upper dead center and the inlet opening immediately afterward. The
+reason why a certain amount of lag is given the exhaust closing in
+practice is that the piston cannot drive the gases out of the cylinder
+unless they are compressed to a degree in excess of that existing in the
+manifold or passages, and while toward the end of the stroke this
+pressure may be feeble, it is nevertheless indispensable. At the end of
+the piston's stroke, as marked by the upper dead center, this
+compression still exists, no matter how little it may be, so that if the
+exhaust valve is closed and the inlet opened immediately afterward, the
+pressure which exists in the cylinder may retard the entrance of the
+fresh gas and a certain portion of the inert gas may penetrate into the
+manifold. As the piston immediately begins to aspirate, this may not be
+serious, but as these gases are drawn back into the cylinder the fresh
+charge will be diluted and weakened in value. If the spark-plug is in a
+pocket, the points may be surrounded by this weak gas, and the explosion
+will not be nearly as energetic as when the ignition spark takes place
+in pure mixture.
+
+It is a well-known fact that the exhaust valve should close after dead
+center and that a certain amount of lag should be given to opening of
+the inlet. The lag given the closing of the exhaust valve should not be
+as great as that given the closing of the inlet valve. Assuming that the
+excess pressure of the exhaust will equal the depression during
+aspiration, the time necessary to complete the emptying of the cylinder
+will be proportional to the volume of the gas within it. At the end of
+the suction stroke the volume of gas contained in the cylinder is equal
+to the cylindrical volume plus the space of the combustion chamber. At
+the end of the exhaust stroke the volume is but that of the dead space,
+and from one-third to one-fifth its volume before compression. While it
+is natural to assume that this excess of burned gas will escape faster
+than the fresh gas will enter the cylinder, it will be seen that if the
+inlet valve were allowed to lag twenty degrees, the exhaust valve lag
+need not be more than five degrees, providing that the capacity of the
+combustion chamber was such that the gases occupied one-quarter of their
+former volume.
+
+It is evident that no absolute rule can be given, as back pressure will
+vary with the design of the valve passages, the manifolds, and the
+construction of the muffler. The more direct the opening, the sooner the
+valve can be closed and the better the cylinder cleared. Ten degrees
+represent an appreciable angle of the crank, and the time required for
+the crank to cover this angular motion is not inconsiderable and an
+important quantity of the exhaust may escape, but the piston is very
+close to the dead center after the distance has been covered.
+
+Before the inlet valve opens there should be a certain depression in the
+cylinder, and considerable lag may be allowed before the depression is
+appreciable. So far as the volume of fresh gas introduced during the
+admission stroke is concerned, this is determined by the displacement of
+the piston between the point where the inlet valve opens and the point
+of closing, assuming that sufficient gas has been inspired so that an
+equilibrium of pressure has been established between the interior of the
+cylinder and the outer air. The point of inlet opening varies with
+different motors. It would appear that a fair amount of lag would be
+fifteen degrees past top center for the inlet opening, as a certain
+depression will exist in the cylinder, assuming that the exhaust valve
+has closed five or ten degrees after center, and at the same time the
+piston has not gone down far enough on its stroke to materially decrease
+the amount of gas which will be taken into the cylinder.
+
+
+CLOSING THE INLET VALVE
+
+As in the case with the other points of opening and closing, there is a
+wide diversity of practice as relates to closing the inlet valve. Some
+of the designers close this exactly at bottom center, but this practice
+cannot be commended, as there is a considerable portion of time, at
+least ten or fifteen degrees angular motion of the crank, before the
+piston will commence to travel to any extent on its compression stroke.
+The gases rushing into the cylinder have considerable velocity, and
+unless an equilibrium is obtained between the pressure inside and that
+of the atmosphere outside, they will continue to rush into the cylinder
+even after the piston ceases to exert any suction effect.
+
+For this reason, if the valve is closed exactly on center, a full charge
+may not be inspired into the cylinder, though if the time of closing is
+delayed, this momentum or inertia of the gas will be enough to insure
+that a maximum charge is taken into the cylinder. The writer considers
+that nothing will be gained if the valve is allowed to remain open
+longer than twenty degrees, and an analysis of practice in this respect
+would seem to confirm this opinion. From that point in the crank
+movement the piston travel increases and the compressive effect is
+appreciable, and it would appear that a considerable proportion of the
+charge might be exhausted into the manifold and carburetor if the valve
+were allowed to remain open beyond a point corresponding to twenty
+degrees angular movement of the crank.
+
+
+TIME OF IGNITION
+
+In this country engineers unite in providing a variable time of
+ignition, though abroad some difference of opinion is noted on this
+point. The practice of advancing the time of ignition, when affected
+electrically, was severely condemned by early makers, these maintaining
+that it was necessary because of insufficient heat and volume of the
+spark, and it was thought that advancing ignition was injurious. The
+engineers of to-day appreciate the fact that the heat of the electric
+spark, especially when from a mechanical generator of electrical energy,
+is the only means by which we can obtain practically instantaneous
+explosion, as required by the operation of motors at high speeds, and
+for the combustion of large volumes of gas.
+
+[Illustration: Fig. 108.--Diagrams Explaining Valve and Ignition Timing
+of Hall-Scott Aviation Engine.]
+
+It is apparent that a motor with a fixed point of ignition is not as
+desirable, in every way, as one in which the ignition can be advanced to
+best meet different requirements, and the writer does not readily
+perceive any advantage outside of simplicity of control in establishing
+a fixed point of ignition. In fact, there seems to be some difference of
+opinion among those designers who favor fixed ignition, and in one case
+this is located forty-three degrees ahead of center, and in another
+motor the point is fixed at twenty degrees, so that it may be said that
+this will vary as much as one hundred per cent. in various forms. This
+point will vary with different methods of ignition, as well as the
+location of the spark-plug or igniter. For the sake of simplicity, most
+airplane engines use set spark; if an advancing and retarding mechanism
+is fitted, it is only to facilitate starting, as the spark is kept
+advanced while in flight, and control is by throttle alone.
+
+[Illustration: Fig. 109.--Timing Diagram of Typical Six-Cylinder
+Engine.]
+
+It is obvious by consideration of the foregoing that there can be no
+arbitrary rules established for timing, because of the many conditions
+which determine the best times for opening and closing the valves. It is
+customary to try various settings when a new motor is designed until the
+most satisfactory points are determined, and the setting which will be
+very suitable for one motor is not always right for one of different
+design. The timing diagram shown at Fig. 108 applies to the Hall-Scott
+engine, and may be considered typical. It should be easily followed in
+view of the very complete explanation given in preceding pages. Another
+six-cylinder engine diagram is shown at Fig. 109, and an eight-cylinder
+timing diagram is shown at Fig. 110. In timing automobile engines no
+trouble is experienced, because timing marks are always indicated on
+the engine fly-wheel register with an indicating trammel on the
+crank-case. To time an airplane engine accurately, as is necessary to
+test for a suspected cam-shaft defect, a timing disc of aluminum is
+attached to the crank-shaft which has the timing marks indicated
+thereon. If the disc is made 10 or 12 inches in diameter, it may be
+divided into degrees without difficulty.
+
+[Illustration: Fig. 110.--Timing Diagram of Typical Eight-Cylinder V
+Engine.]
+
+
+HOW AN ENGINE IS TIMED
+
+In timing a motor from the marks on the timing disc rim it is necessary
+to regulate the valves of but one cylinder at a time. Assuming that the
+disc is revolving in the direction of engine rotation, and that the
+firing order of the cylinders is 1-3-4-2, the operation of timing would
+be carried on as follows: The crank-shaft would be revolved until the
+line marked "Exhaust opens 1 and 4" registered with the trammel on the
+motor bed. At this point the exhaust-valve of either cylinder No. 1 or
+No. 4 should begin to open. This can be easily determined by noting
+which of these cylinders holds the compressed charge ready for ignition.
+Assuming that the spark has occurred in cylinder No. 1, then when the
+fly-wheel is turned from the position to that in which the line marked
+"Exhaust opens 1 and 4" coincides with the trammel point, the
+valve-plunger under the exhaust-valve of cylinder No. 1 should be
+adjusted in such a way that there is no clearance between it and the
+valve stem. Further movement of the wheel in the same direction should
+produce a lift of the exhaust valve. The disc is turned about two
+hundred and twenty-five degrees, or a little less than three-quarters of
+a revolution; then the line marked "Exhaust closes 1 and 4" will
+register with the trammel point. At this period the valve-plunger and
+the valve-stem should separate and a certain amount of clearance obtain
+between them. The next cylinder to time would be No. 3. The crank-shaft
+is rotated until mark "Exhaust opens 2 and 3" comes in line with the
+trammel. At this point the exhaust valve of cylinder No. 3 should be
+just about opening. The closing is determined by rotating the shaft
+until the line "Exhaust closes 2 and 3" comes under the trammel.
+
+This operation is carried on with all the cylinders, it being well to
+remember that but one cylinder is working at a time and that a
+half-revolution of the fly-wheel corresponds to a full working stroke of
+all the cylinders, and that while one is exhausting the others are
+respectively taking in a new charge, compressing and exploding. For
+instance, if cylinder No. 1 has just completed its power-stroke, the
+piston in cylinder No. 3 has reached the point where the gas may be
+ignited to advantage. The piston of cylinder No. 4, which is next to
+fire, is at the bottom of its stroke and will have inspired a charge,
+while cylinder No. 2, which is the last to fire, will have just finished
+expelling a charge of burned gas, and will be starting the intake
+stroke. This timing relates to a four-cylinder engine in order to
+simplify the explanation. The timing instructions given apply only to
+the conventional motor types. Rotary cylinder engines, especially the
+Gnome "monosoupape," have a distinctive valve timing on account of the
+peculiarities of design.
+
+
+GNOME "MONOSOUPAPE" VALVE TIMING
+
+In the present design of the Gnome motor, a cycle of operations somewhat
+different from that employed in the ordinary four-cycle engine is made
+use of, says a writer in "The Automobile," in describing the action of
+this power-plant. This cycle does away with the need for the usual inlet
+valve and makes the engine operable with only a single valve, hence the
+name _monosoupape_, or "single-valve." The cycle is as follows: A charge
+being compressed in the outer end of the cylinder or combustion chamber,
+it is ignited by a spark produced by the spark-plug located in the side
+of this chamber, and the burning charge expands as the piston moves down
+in the cylinder while the latter revolves around the crank-shaft. When
+the piston is about half-way down on the power stroke, the exhaust
+valve, which is located in the center of the cylinder-head, is
+mechanically opened, and during the following upstroke of the piston the
+burnt gases are expelled from the cylinder through the exhaust valve
+directly into the atmosphere.
+
+Instead of closing at the end of the exhaust stroke, or a few degrees
+thereafter, the exhaust valve is held open for about two-thirds of the
+following inlet stroke of the piston, with the result that fresh air is
+drawn through the exhaust valve into the cylinder. When the cylinder is
+still 65 degrees from the end of the inlet half-revolution, the exhaust
+valve closes. As no more air can get into the cylinder, and as the
+piston continues to move inwardly, it is obvious that a partial vacuum
+is formed.
+
+When the cylinder approaches within 20 degrees of the end of the inlet
+half-revolution a series of small inlet ports all around the
+circumference of the cylinder wall is uncovered by the top edge of the
+piston, whereby the combustion chamber is placed in communication with
+the crank chamber. As the pressure in the crank chamber is substantially
+atmospheric and that in the combustion chamber is below atmospheric,
+there results a suction effect which causes the air from the crank
+chamber to flow into the combustion chamber. The air in the crank
+chamber is heavily charged with gasoline vapor, which is due to the fact
+that a spray nozzle connected with the gasoline supply tank is located
+inside the chamber. The proportion of gasoline vapor in the air in the
+crank chamber is several times as great as in the ordinary combustible
+mixture drawn from a carburetor into the cylinder. This extra-rich
+mixture is diluted in the combustion chamber with the air which entered
+it through the exhaust valve during the first part of the inlet stroke,
+thus forming a mixture of the proper proportion for complete combustion.
+
+The inlet ports in the cylinder wall remain open until 20 degrees of
+the compression half-revolution has been completed, and from that moment
+to near the end of the compression stroke the gases are compressed in
+the cylinder. Near the end of the stroke ignition takes place and this
+completes the cycle.
+
+The exact timing of the different phases of the cycle is shown in the
+diagram at Fig. 111. It will be seen that ignition occurs substantially
+20 degrees ahead of the outer dead center, and expansion of the burning
+gases continues until 85 degrees past the outer dead center, when the
+piston is a little past half-stroke. Then the exhaust-valve opens and
+remains open for somewhat more than a complete revolution of the
+cylinders, or, to be exact, for 390 degrees of cylinder travel, until
+115 degrees past the top dead center on the second revolution. Then for
+45 degrees of travel the charge within the cylinder is expanded,
+whereupon the inlet ports are uncovered and remain open for 40 degrees
+of cylinder travel, 20 degrees on each side of the inward dead center
+position.
+
+
+SPRINGLESS VALVES
+
+Springless valves are the latest development on French racing car
+engines, and it is possible that the positively-operated types will be
+introduced on aviation engines also. Two makes of positively-actuated
+valves are shown at Fig. 112. The positive-valve motor differs from the
+conventional form by having no necessity for valve-springs, as a cam not
+only assures the opening of the valve, but also causes it to return to
+the valve-seat. In this respect it is much like the sleeve-valve motor,
+where the uncovering of the ports is absolutely positive. The cars
+equipped with these valves were a success in long-distance auto races.
+Claims made for this type of valve mechanism include the possibility of
+a higher number of revolutions and consequently greater engine power.
+With the spring-controlled, single-cam operated valve a point is reached
+where the spring is not capable of returning the valve to its seat
+before the cam has again begun its opening movement. It is possible to
+extend the limits considerably by using a light valve on a strong
+spring, but the valve still remains a limiting factor in the speed of
+the motor.
+
+[Illustration: Fig. 111.--Timing Diagram Showing Peculiar Valve Timing
+of Gnome "Monosoupape" Rotary Motor.]
+
+A part sectional view through a cylinder of an engine designed by G.
+Michaux is shown at Fig. 112, A. There are two valves per cylinder,
+inclined at about ten degrees from the vertical. The valve-stems are of
+large diameter, as owing to positive control, there is no necessity of
+lightening this part in an unusual degree. A single overhead cam-shaft
+has eight pairs of cams, which are shown in detail at B. For each valve
+there is a three-armed rocker, one arm of which is connected to the stem
+of the valve and the two others are in contact respectively with the
+opening and closing cams. The connection to the end of the valve-stem is
+made by a short connecting link, which is screwed on to the end of the
+valve-stem and locked in position. This allows some adjustment to be
+made between the valves and the actuating rocker. It will be evident
+that one cam and one rocker arm produce the opening of the valve and
+that the corresponding rocker arm and cam result in the closing of the
+valve. If the opening cam has the usual convex profile, the closing cam
+has a correspondingly concave profile. It will be noticed that a light
+valve-spring is shown in drawing. This is provided to give a final
+seating to its valve after it has been closed by the cam. This is not
+absolutely necessary, as an engine has been run successfully without
+these springs. The whole mechanism is contained within an overhead
+aluminum cover.
+
+[Illustration: Fig. 112.--Two Methods of Operating Valves by Positive
+Cam Mechanism Which Closes as Well as Opens Them.]
+
+The positive-valve system used on the De Lage motor is shown at D. In
+this the valves are actuated as shown in sectional views D and E. The
+valve system is unique in that four valves are provided per cylinder,
+two for exhaust and two for intake. The valves are mounted side by side,
+as shown at E, so the double actuator member may be operated by a single
+set of cams. The valve-operating member consists of a yoke having guide
+bars at the top and bottom. The actuating cam works inside of this yoke.
+The usual form of cam acts on the lower portion of the yoke to open the
+valve, while the concave cam acts on the upper part to close the valves.
+In this design provision is made for expansion of the valve-stems due to
+heat, and these are not positively connected to the actuating member. As
+shown at E, the valves are held against the seat by short coil springs
+at the upper end of the stem. These are very stiff and are only intended
+to provide for expansion. A slight space is left between the top of the
+valve-stem and the portion of the operating member that bears against
+them when the regular profile cam exerts its pressure on the bottom of
+the valve-operating mechanism. Another novelty in this motor design is
+that the cam-shafts and the valve-operating members are carried in
+casing attached above the motor by housing supports in the form of small
+steel pillars. The overhead cam-shafts are operated by means of bevel
+gearing.
+
+
+FOUR VALVES PER CYLINDER
+
+[Illustration: Fig. 113.--Diagram Comparing Two Large Valves and Four
+Small Ones of Practically the Same Area. Note How Easily Small Valves
+are Installed to Open Directly Into the Cylinder.]
+
+Mention has been previously made of the sixteen-valve four-cylinder
+Duesenberg motor and its great power output for the piston displacement.
+This is made possible by the superior volumetric efficiency of a motor
+provided with four valves in each cylinder instead of but two. This
+principle was thoroughly tried out in racing automobile motors, and is
+especially valuable in permitting of greater speed and power output from
+simple four- and six-cylinder engines. On eight- and twelve-cylinder
+types, it is doubtful if the resulting complication due to using a very
+large number of valves would be worth while. When extremely large valves
+are used, as shown in diagram at Fig. 113, it is difficult to have them
+open directly into the cylinder, and pockets are sometimes necessary. A
+large valve would weigh more than two smaller valves having an area
+slightly larger in the aggregate; it would require a stiffer valve
+spring on account of its greater weight. A certain amount of metal in
+the valve-head is necessary to prevent warping; therefore, the inertia
+forces will be greater in the large valve than in the two smaller
+valves. As a greater port area is obtained by the use of two valves,
+the gases will be drawn into the cylinder or expelled faster than with a
+lesser area. Even if the areas are practically the same as in the
+diagram at Fig. 113, the smaller valves may have a greater lift without
+imposing greater stresses on the valve-operating mechanism and quicker
+gas intake and exhaust obtained. The smaller valves are not affected by
+heat as much as larger ones are. The quicker gas movements made
+possible, as well as reduction of inertia forces, permits of higher
+rotative speed, and, consequently, greater power output for a given
+piston displacement. The drawings at Fig. 114 show a sixteen-valve motor
+of the four-cylinder type that has been designed for automobile racing
+purposes, and it is apparent that very slight modifications would make
+it suitable for aviation purposes. Part of the efficiency is due to the
+reduction of bearing friction by the use of ball bearings, but the
+multiple-valve feature is primarily responsible for the excellent
+performance.
+
+[Illustration: Fig. 114.--Sectional Views of Sixteen-Valve Four-Cylinder
+Automobile Racing Engine That May Have Possibilities for Aviation
+Service.]
+
+[Illustration: Fig. 115.--Front View of Curtiss OX-3 Aviation Motor,
+Showing Unconventional Valve Action by Concentric Push Rod and Pull
+Tube.]
+
+
+
+
+CHAPTER IX
+
+    Constructional Details of Pistons--Aluminum Cylinders and
+    Pistons--Piston Ring Construction--Leak Proof Piston Rings--
+    Keeping Oil Out of Combustion Chamber--Connecting Rod Forms--
+    Connecting Rods for Vee Engines--Cam-Shaft and Crank-Shaft
+    Designs--Ball Bearing Crank-Shafts--Engine Base Construction.
+
+
+CONSTRUCTIONAL DETAILS OF PISTONS
+
+The piston is one of the most important parts of the gasoline motor
+inasmuch as it is the reciprocating member that receives the impact of
+the explosion and which transforms the power obtained by the combustion
+of gas to mechanical motion by means of the connecting rod to which it
+is attached. The piston is one of the simplest elements of the motor,
+and it is one component which does not vary much in form in different
+types of motors. The piston is a cylindrical member provided with a
+series of grooves in which packing rings are placed on the outside and
+two bosses which serve to hold the wrist pin in its interior. It is
+usually made of cast iron or aluminum, though in some motors where
+extreme lightness is desired, such as those used for aeronautic work, it
+may be made of steel. The use of the more resisting material enables the
+engineer to use lighter sections where it is important that the weight
+of this member be kept as low as possible consistent with strength.
+
+[Illustration: Fig. 116.--Forms of Pistons Commonly Employed in Gasoline
+Engines. A--Dome Head Piston and Three Packing Rings. B--Flat Top Form
+Almost Universally Used. C--Concave Piston Utilized in Knight Motors and
+Some Having Overhead Valves. D--Two-Cycle Engine Member with Deflector
+Plate Cast Integrally. E--Differential of Two-Diameter Piston Used in
+Some Engines Operating on Two-Cycle Principle.]
+
+A number of piston types are shown at Fig. 116. That at A has a round
+top and is provided with four split packing rings and two oil grooves. A
+piston of this type is generally employed in motors where the combustion
+chamber is large and where it is desired to obtain a higher degree of
+compression than would be possible with a flat top piston. This
+construction is also stronger because of the arched piston top. The most
+common form of piston is that shown at B, and it differs from that
+previously described only in that it has a flat top. The piston outlined
+in section at C is a type used on some of the sleeve-valve motors of the
+Knight pattern, and has a concave head instead of the convex form shown
+at A. The design shown at D in side and plan views is the conventional
+form employed in two-cycle engines. The deflector plate on the top of
+the cylinder is cast integral and is utilized to prevent the incoming
+fresh gases from flowing directly over the piston top and out of the
+exhaust port, which is usually opposite the inlet opening. On these
+types of two-cycle engines where a two-diameter cylinder is employed,
+the piston shown at E is used. This is known as a "differential
+piston," and has an enlarged portion at its lower end which fits the
+pumping cylinder. The usual form of deflector plate is provided at the
+top of the piston and one may consider it as two pistons in one.
+
+[Illustration: Fig. 117.--Typical Methods of Piston Pin Retention
+Generally Used in Engines of American Design. A--Single Set Screw and
+Lock Nut. B--Set Screw and Check Nut Fitting Groove in Wrist Pin. C,
+D--Two Locking Screws Passing Into Interior of Hollow Wrist Pin.
+E--Split Ring Holds Pin in Place. F--Use of Taper Expanding Plugs
+Outlined. G--Spring Pressed Plunger Type. H--Piston Pin Pinned to
+Connecting Rod. I--Wrist Pin Clamped in Connecting Rod Small End by
+Bolt.]
+
+[Illustration: Fig. 118.--Typical Piston and Connecting Rod Assembly.]
+
+[Illustration: Fig. 119.--Parts of Sturtevant Aviation Engine.
+A--Cylinder Head Showing Valves. B--Connecting Rod. C--Piston and
+Rings.]
+
+One of the important conditions in piston design is the method of
+securing the wrist pin which is used to connect the piston to the upper
+end of the connecting rod. Various methods have been devised to keep the
+pin in place, the most common of these being shown at Fig. 117. The
+wrist pin should be retained by some positive means which is not liable
+to become loose under the vibratory stresses which obtain at this point.
+If the wrist pin was free to move it would work out of the bosses
+enough so that the end would bear against the cylinder wall. As it is
+usually made of steel, which is a harder material than cast iron used in
+cylinder construction, the rubbing action would tend to cut a groove in
+the cylinder wall which would make for loss of power because it would
+permit escape of gas. The wrist pin member is a simple cylindrical
+element that fits the bosses closely, and it may be either hollow or
+solid stock. A typical piston and connecting rod assembly which shows a
+piston in section also is given at Fig. 118. The piston of the
+Sturtevant aeronautical motor is shown at Fig. 119, the aluminum piston
+of the Thomas airplane motor with piston rings in place is shown at Fig.
+120. A good view of the wrist pin and connecting rod are also given. The
+iron piston of the Gnome "Monosoupape" airplane engine and the
+unconventional connecting rod assembly are clearly depicted at Fig 121.
+
+[Illustration: Fig. 120.--Aluminum Piston and Light But Strong Steel
+Connecting Rod and Wrist Pin of Thomas Aviation Engine.]
+
+The method of retention shown at A is the simplest and consists of a set
+screw having a projecting portion passing into the wrist pin and
+holding it in place. The screw is kept from turning or loosening by
+means of a check nut. The method outlined at B is similar to that shown
+at A, except that the wrist pin is solid and the point of the set screw
+engages an annular groove turned in the pin for its reception. A very
+positive method is shown at C. Here the retention screws pass into the
+wrist pin and are then locked by a piece of steel wire which passes
+through suitable holes in the ends. The method outlined at D is
+sometimes employed, and it varies from that shown at C only in that the
+locking wire, which is made of spring steel, is passed through the heads
+of the locking screws. Some designers machine a large groove around the
+piston at such a point that when the wrist pin is put in place a large
+packing ring may be sprung in the groove and utilized to hold the wrist
+pin in place.
+
+[Illustration: Fig. 121.--Cast Iron Piston of "Monosoupape" Gnome Engine
+Installed On One of the Short Connecting Rods.]
+
+The system shown at F is not so widely used as the simpler methods,
+because it is more costly and does not offer any greater security when
+the parts are new than the simple lock shown at A. In this a hollow
+wrist pin is used, having a tapered thread cut at each end. The wrist
+pin is slotted at three or four points, for a distance equal to the
+length of the boss, and when taper expansion plugs are screwed in place
+the ends of the wrist pin are expanded against the bosses. This method
+has the advantage of providing a certain degree of adjustment if the
+wrist pin should loosen up after it has been in use for some time. The
+taper plugs would be screwed in deeper and the ends of the wrist pin
+expanded proportionately to take up the loss motion. The method shown at
+G is an ingenious one. One of the piston bosses is provided with a
+projection which is drilled out to receive a plunger. The wrist pin is
+provided with a hole of sufficient size to receive the plunger, which is
+kept in place by means of a spring in back of it. This makes a very
+positive lock and one that can be easily loosened when it is desired to
+remove the wrist pin. To unlock, a piece of fine rod is thrust into the
+hole at the bottom of the boss which pushes the plunger back against the
+spring until the wrist pin can be pushed out of the piston.
+
+Some engineers think it advisable to oscillate the wrist pin in the
+piston bosses, instead of in the connecting rod small end. It is argued
+that this construction gives more bearing surface at the wrist pin and
+also provides for more strength because of the longer bosses that can be
+used. When this system is followed the piston pin is held in place by
+locking it to the connecting rod by some means. At H the simplest method
+is outlined. This consisted of driving a taper pin through both rod and
+wrist pin and then preventing it from backing out by putting a split
+cotter through the small end of the tapered locking pin. Another method,
+which is depicted at I, consists of clamping the wrist pin by means of a
+suitable bolt which brings the slit connecting rod end together as
+shown.
+
+
+ALUMINUM FOR CYLINDERS AND PISTONS
+
+Aluminum pistons outlined at Fig. 122, have replaced cast iron members
+in many airplane engines, as these weigh about one-third as much as the
+cast iron forms of the same size, while the reduction in the inertia
+forces has made it possible to increase the engine speed without
+correspondingly stressing the connecting rods, crank-shaft and engine
+bearings.
+
+[Illustration: Fig. 122.--Types of Aluminum Pistons Used In Aviation
+Engines.]
+
+Aluminum has not only been used for pistons, but a number of motors will
+be built for the coming season that will use aluminum cylinder block
+castings as well. Of course, the aluminum alloy is too soft to be used
+as a bearing for the piston, and it will not withstand the hammering
+action of the valve. This makes the use of cast iron or steel imperative
+in all motors. When used in connection with an aluminum cylinder block
+the cast iron pieces are placed in the mould so that they act as
+cylinder liners and valve seats, and the molten metal is poured around
+them when the cylinder is cast. It is said that this construction
+results in an intimate bond between the cast iron and the surrounding
+aluminum metal. Steel liners may also be pressed into the aluminum
+cylinders after these are bored out to receive them. Aluminum has for a
+number of years been used in many motor car parts. Alloys have been
+developed that have greater strength than cast iron and that are not so
+brittle. Its use for manifolds and engine crank and gear cases has been
+general for a number of years.
+
+At first thought it would seem as though aluminum would be entirely
+unsuited for use in those portions of internal combustion engines
+exposed to the heat of the explosion, on account of the low melting
+point of that metal and its disadvantageous quality of suddenly
+"wilting" when a critical point in the temperature is reached. Those who
+hesitated to use aluminum on account of this defect lost sight of the
+great heat conductivity of that metal, which is considerably more than
+that of cast iron. It was found in early experiments with aluminum
+pistons that this quality of quick radiation meant that aluminum pistons
+remained considerably cooler than cast iron ones in service, which was
+attested to by the reduced formation of carbon deposit thereon. The use
+of aluminum makes possible a marked reduction in power plant weight. A
+small four-cylinder engine which was not particularly heavy even with
+cast iron cylinders was found to weigh 100 pounds less when the cylinder
+block, pistons, and upper half of the crank-case had been made of
+aluminum instead of cast iron. Aluminum motors are no longer an
+experiment, as a considerable number of these have been in use on cars
+during the past year without the owners of the cars being apprised of
+the fact. Absolutely no complaint was made in any case of the aluminum
+motor and it was demonstrated, in addition to the saving in weight, that
+the motors cost no more to assemble and cooled much more efficiently
+than the cast iron form. One of the drawbacks to the use of aluminum is
+its growing scarcity, which results in making it a "near precious"
+metal.
+
+
+PISTON RING CONSTRUCTION
+
+As all pistons must be free to move up and down in the cylinder with
+minimum friction, they must be less in diameter than the bore of the
+cylinder. The amount of freedom or clearance provided varies with the
+construction of the engine and the material the piston is made of, as
+well as its size, but it is usual to provide from .005 to .010 of an
+inch to compensate for the expansion of the piston due to heat and also
+to leave sufficient clearance for the introduction of lubricant between
+the working surfaces. Obviously, if the piston were not provided with
+packing rings, this amount of clearance would enable a portion of the
+gases evolved when the charge is exploded to escape by it into the
+engine crank-case. The packing members or piston rings, as they are
+called, are split rings of cast iron, which are sprung into suitable
+grooves machined on the exterior of the piston, three or four of these
+being the usual number supplied. These have sufficient elasticity so
+that they bear tightly against the cylinder wall and thus make a
+gas-tight joint. Owing to the limited amount of surface in contact with
+the cylinder wall and the elasticity of the split rings the amount of
+friction resulting from the contact of properly fitted rings and the
+cylinder is not of enough moment to cause any damage and the piston is
+free to slide up and down in the cylinder bore.
+
+[Illustration: Fig. 123.--Types of Piston Rings and Ring Joints.
+A--Concentric Ring. B--Eccentrically Machined Form. C--Lap Joint Ring.
+D--Butt Joint, Seldom Used. E--Diagonal Cut Member, a Popular Form.]
+
+These rings are made in two forms, as outlined at Fig. 123. The design
+shown at A is termed a "concentric ring," because the inner circle is
+concentric with the outer one and the ring is of uniform thickness at
+all points. The ring shown at B is called an "eccentric ring," and it is
+thicker at one part than at others. It has theoretical advantages in
+that it will make a tighter joint than the other form, as it is claimed
+its expansion due to heat is more uniform. The piston rings must be
+split in order that they may be sprung in place in the grooves, and also
+to insure that they will have sufficient elasticity to take the form of
+the cylinder at the different points in their travel. If the cylinder
+bore varies by small amounts the rings will spring out at the points
+where the bore is larger than standard, and spring in at those portions
+where it is smaller than standard.
+
+It is important that the joint should be as nearly gas-tight as
+possible, because if it were not a portion of the gases would escape
+through the slots in the piston rings. The joint shown at C is termed a
+"lap joint," because the ends of the ring are cut in such a manner that
+they overlap. This is the approved joint. The butt joint shown at D is
+seldom used and is a very poor form, the only advantage being its
+cheapness. The diagonal cut shown at E is a compromise between the very
+good form shown at C and the poor joint depicted at D. It is also widely
+used, though most constructors prefer the lap joint, because it does not
+permit the leakage of gas as much as the other two types.
+
+There seems to be some difference of opinion relative to the best piston
+ring type--some favoring the eccentric pattern, others the concentric
+form. The concentric ring has advantages from the lubricating engineer's
+point of view; as stated by the Platt & Washburn Company in their
+text-book on engine lubrication, the smaller clearance behind the ring
+possible with the ring of uniform section is advantageous.
+
+Fig. 124, A, shows a concentric piston ring in its groove. Since the
+ring itself is concentric with the groove, very small clearance between
+the back of the ring and the bottom of its groove may be allowed. Small
+clearance leaves less space for the accumulation of oil and carbon
+deposits. The gasket effect of this ring is uniform throughout the
+entire length of its edges, which is its marked advantage over the
+eccentric ring. This type of piston ring rarely burns fast in its
+groove. There are a large number of different concentric rings
+manufactured of different designs and of different efficiency.
+
+[Illustration: Fig. 124.--Diagrams Showing Advantages of Concentric
+Piston Rings.]
+
+Figs. 124, B and 124, C show eccentric rings assembled in the ring
+groove. It will be noted that there is a large space between the thin
+ends of this ring and the bottom of the groove. This empty space fills
+up with oil which in the case of the upper ring frequently is
+carbonized, restricting the action of the ring and nullifying its
+usefulness. The edges of the thin ends are not sufficiently wide to
+prevent rapid escape of gases past them. In a practical way this leakage
+means loss of compression and noticeable drop in power. When new and
+properly fitted, very little difference can be noted between the
+tightness of eccentric and concentric rings. Nevertheless, after several
+months' use, a more rapid leakage will always occur past the eccentric
+than past the concentric. If continuous trouble with the carbonization
+of cylinders, smoking and sooting of spark-plugs is experienced, it is
+a sure indication that mechanical defects exist in the engine, assuming
+of course, that a suitable oil has been used. Such trouble can be
+greatly lessened, if not entirely eliminated, by the application of
+concentric rings (lap joint), of any good make, properly fitted into the
+grooves of the piston. Too much emphasis cannot be put upon this point.
+If the oil used in the engine is of the correct viscosity, and serious
+carbon deposit, smoking, etc., still result, the only certain remedy
+then is to have the cylinders rebored and fitted with properly designed,
+oversized pistons and piston rings.
+
+
+LEAK-PROOF PISTON RINGS
+
+In order to reduce the compression loss and leakage of gas by the
+ordinary simple form of diagonal or lap joint one-piece piston ring a
+number of compound rings have been devised and are offered by their
+makers to use in making replacements. The leading forms are shown at
+Fig. 125. That shown at A is known as the "Statite" and consists of
+three rings, one carried inside while the other two are carried on the
+outside. The ring shown at B is a double ring and is known as the
+McCadden. This is composed of two thin concentric lap joint rings so
+disposed relative to each other that the opening in the inner ring comes
+opposite to the opening in the outer ring.
+
+The form shown at C is known as the "Leektite," and is a single ring
+provided with a peculiar form of lap and dove tail joint. The ring shown
+at D is known as the "Dunham" and is of the double concentric type being
+composed of two rings with lap joints which are welded together at a
+point opposite the joint so that there is no passage by which the gas
+can escape. The Burd high compression ring is shown at E. The joints of
+these rings are sealed by means of an H-shaped coupler of bronze which
+closes the opening. The ring ends are made with tongues which interlock
+with the coupling. The ring shown at F is called the "Evertite" and is
+a three-piece ring composed of three members as shown in the sectional
+view below the ring. The main part or inner ring has a circumferential
+channel in which the two outer rings lock, the resulting cross-section
+being rectangular just the same as that of a regular pattern ring. All
+three rings are diagonally split and the joints are spaced equally and
+the distances maintained by small pins. This results in each joint being
+sealed by the solid portion of the other rings.
+
+[Illustration: Fig. 125.--Leak-Proof and Other Compound Piston Rings.]
+
+The use of a number of light steel rings instead of one wide ring in the
+groove is found on a number of automobile power plants, but as far as
+known, this construction is not used in airplane power plants. It is
+contended that where a number of light rings is employed a more flexible
+packing means is obtained and the possibility of leakage is reduced.
+Rings of this design are made of square section steel wire and are given
+a spring temper. Owing to the limited width the diagonal cut joint is
+generally employed instead of the lap joint which is so popular on wider
+rings.
+
+
+KEEPING OIL OUT OF COMBUSTION CHAMBERS
+
+An examination of the engine design that is economical in oil
+consumption discloses the use of tight piston rings, large centrifugal
+rings on the crank-shaft where it passes through the case, ample cooling
+fins in the pistons, vents between the crank-case chamber and the valve
+enclosures, etc. Briefly put, cooling of the oil in this engine has been
+properly cared for and leakage reduced to a minimum. To be specific
+regarding details of design: Oil surplus can be kept out of the
+explosion chambers by leaving the lower edge of the piston skirt sharp
+and by the use of a shallow groove (C), Fig. 126, just below the lower
+piston ring. Small holes are bored through the piston walls at the base
+of this groove and communicate with the crank-case. The similarity of
+the sharp edges of piston skirt (D) and piston ring to a carpenter's
+plane bit, makes their operation plain.
+
+[Illustration: Fig. 126.--Sectional View of Engine Showing Means of
+Preventing Oil Leakage By Piston Rings.]
+
+The cooling of oil in the sump (A) can be accomplished most effectively
+by radiating fins on its outer surface. The lower crank-case should be
+fully exposed to the outer air. A settling basin for sediment (B) should
+be provided having a cubic content not less than one-tenth of the total
+oil capacity as outlined at Fig. 126. The depth of this basin should be
+at least 2-1/2 inches, and its walls vertical, as shown, to reduce the
+mixing of sediment with the oil in circulation. The inlet opening to the
+oil pump should be near the top of the sediment basin in order to
+prevent the entrance into the pump with the oil of any solid matter or
+water condensed from the products of combustion. This sediment basin
+should be drained after every five to seven hours air service of an
+airplane engine. Concerning filtering screens there is little to be
+said, save that their areas should be ample and the mesh coarse enough
+(one-sixteenth of an inch) to offer no serious resistance to the free
+flow of cold or heavy oil through them; otherwise the oil in the
+crank-case may build up above them to an undesirable level. The
+necessary frequency of draining and flushing out the oil sump differs
+greatly with the age (condition) of the engine and the suitability of
+the oil used. In broad terms, the oil sump of a new engine should be
+thoroughly drained and flushed with kerosene at the end of the first
+200 miles, next at the end of 500 miles and thereafter every 1,000
+miles. While these instructions apply specifically to automobile motors,
+it is very good practice to change the oil in airplane engines
+frequently. In many cases, the best results have been secured when the
+oil supply is completely replenished every five hours that the engine is
+in operation.
+
+
+CONNECTING ROD FORMS
+
+The connecting rod is the simple member that joins the piston to the
+crank-shaft and which transmits the power imparted to the piston by the
+explosion so that it may be usefully applied. It transforms the
+reciprocating movement of the piston to a rotary motion at the
+crank-shaft. A typical connecting rod and its wrist pin are shown at
+Fig. 120. It will be seen that it has two bearings, one at either end.
+The small end is bored out to receive the wrist pin which joins it to
+the piston, while the large end has a hole of sufficient size to go on
+the crank-pin. The airplane and automobile engine connecting rod is
+invariably a steel forging, though in marine engines it is sometimes
+made a steel or high tensile strength bronze casting. In all cases it is
+desirable to have softer metals than the crank-shaft and wrist pin at
+the bearing point, and for this reason the connecting rod is usually
+provided with bushings of anti-friction or white metal at the lower end,
+and bronze at the upper. The upper end of the connecting rod may be one
+piece, because the wrist pin can be introduced after it is in place
+between the bosses of the piston. The lower bearing must be made in two
+parts in most cases, because the crank-shaft cannot be passed through
+the bearing owing to its irregular form. The rods of the Gnome engine
+are all one piece types, as shown at Fig. 127, owing to the construction
+of the "mother" rod which receives the crank-pins. The complete
+connecting rod assembly is shown in Fig. 121, also at A, Fig. 127. The
+"mother" rod, with one of the other rods in place and one about to be
+inserted, is shown at Fig. 127, B. The built-up crank-shaft which makes
+this construction feasible is shown at Fig. 127, C.
+
+[Illustration: Fig. 127.--Connecting Rod and Crank-Shaft Construction of
+Gnome "Monosoupape" Engine.]
+
+Some of the various designs of connecting rods that have been used are
+shown at Fig. 128. That at A is a simple form often employed in
+single-cylinder motors, having built-up crank-shafts. Both ends of the
+connecting rod are bushed with a one-piece bearing, as it can be
+assembled in place before the crank-shaft assembly is built up. A
+built-up crank-shaft such as this type of connecting rod would be used
+with is shown at Fig. 106. The pattern shown at B is one that has been
+used to some extent on heavy work, and is known as the "marine type." It
+is made in three pieces, the main portion being a steel forging having a
+flanged lower end to which the bronze boxes are secured by bolts. The
+modified marine type depicted at C is the form that has received the
+widest application in automobile and aviation engine construction. It
+consists of two pieces, the main member being a steel drop forging
+having the wrist-pin bearing and the upper crank-pin bearing formed
+integral, while the lower crank-pin bearing member is a separate forging
+secured to the connecting rod by bolts. In this construction bushings of
+anti-friction metal are used at the lower end, and a bronze bushing is
+forced into the upper- or wrist-pin end. The rod shown at D has also
+been widely used. It is similar in construction to the form shown at C,
+except that the upper end is split in order to permit of a degree of
+adjustment of the wrist-pin bushing, and the lower bearing cap is a
+hinged member which is retained by one bolt instead of two. When it is
+desired to assemble it on the crank-shaft the lower cap is swung to one
+side and brought back into place when the connecting rod has been
+properly located. Sometimes the lower bearing member is split diagonally
+instead of horizontally, such a construction being outlined at E.
+
+[Illustration: Fig. 128.--Connecting Rod Types Summarized.
+A--Single Connecting Rod Made in One Piece, Usually Fitted in Small
+Single-Cylinder Engines Having Built-Up Crank-Shafts. B--Marine Type, a
+Popular Form on Heavy Engines. C--Conventional Automobile Type, a
+Modified Marine Form. D--Type Having Hinged Lower Cap and Split Wrist
+Pin Bushing. E--Connecting Rod Having Diagonally Divided Big End.
+F--Ball-Bearing Rod. G--Sections Showing Structural Shapes Commonly
+Employed in Connecting Rod Construction.]
+
+In a number of instances, instead of plain bushed bearings anti-friction
+forms using ball or rollers have been used at the lower end. A
+ball-bearing connecting rod is shown at F. The big end may be made in
+one piece, because if it is possible to get the ball bearing on the
+crank-pins it will be easy to put the connecting rod in place. Ball
+bearings are not used very often on connecting rod big ends because of
+difficulty of installation, though when applied properly they give
+satisfactory service and reduce friction to a minimum. One of the
+advantages of the ball bearing is that it requires no adjustment,
+whereas the plain bushings depicted in the other connecting rods must be
+taken up from time to time to compensate for wear.
+
+This can be done in forms shown at B, C, D, and E by bringing the lower
+bearing caps closer to the upper one and scraping out the brasses to fit
+the shaft. A number of liners or shims of thin brass or copper stock,
+varying from .002 inch to .005 inch, are sometimes interposed between
+the halves of the bearings when it is first fitted to the crank-pin. As
+the brasses wear the shims may be removed and the portions of the
+bearings brought close enough together to take up any lost motion that
+may exist, though in some motors no shims are provided and depreciation
+can be remedied only by installing new brasses and scraping to fit.
+
+[Illustration: Fig. 129.--Double Connecting Rod Assembly For Use On
+Single Crank-Pin of Vee Engine.]
+
+The various structural shapes in which connecting rods are formed are
+shown in section at G. Of these the I section is most widely used in
+airplane engines, because it is strong and a very easy shape to form by
+the drop-forging process or to machine out of the solid bar when extra
+good steel is used. Where extreme lightness is desired, as in small
+high-speed motors used for cycle propulsion, the section shown at the
+extreme left is often used. If the rod is a cast member as in some
+marine engines, the cross, hollow cylinder, or U sections are sometimes
+used. If the sections shown at the right are employed, advantage is
+often taken of the opportunity for passing lubricant through the center
+of the hollow round section on vertical motors or at the bottom of the U
+section, which would be used on a horizontal cylinder power plant.
+
+[Illustration: Fig. 130.--Another Type of Double Connecting Rod for Vee
+Engines.]
+
+Connecting rods of Vee engines are made in two distinct styles. The
+forked or "scissors" joint rod assembly is employed when the cylinders
+are placed directly opposite each other. The "blade" rod, as shown at
+Fig. 129, fits between the lower ends of the forked rod, which oscillate
+on the bearing which encircles the crank-pin. The lower end of the
+"blade" rod is usually attached to the bearing brasses, the ends of the
+"forked" rod move on the outer surfaces of the brasses. Another form of
+rod devised for use under these conditions is shown at Fig. 130 and
+installed in an aviation engine at Fig. 132. In this construction the
+shorter rod is attached to a boss on the master rod by a short pin to
+form a hinge and to permit the short rod to oscillate as the conditions
+dictate. This form of rod can be easily adjusted when the bearing
+depreciates, a procedure that is difficult with the forked type rod. The
+best practice, in the writer's opinion, is to stagger the cylinders and
+use side-by-side rods as is done in the Curtiss engine. Each rod may be
+fitted independently of the other and perfect compensation for wear of
+the big ends is possible.
+
+[Illustration: Fig. 131.--Part Sectional View of Wisconsin Aviation
+Engine, Showing Four-Bearing Crank-Shaft, Overhead Cam-Shaft, and Method
+of Combining Cylinders in Pairs.]
+
+[Illustration: Fig. 132.--Part Sectional View of Renault Twelve-Cylinder
+Water-Cooled Engine, Showing Connecting Rod Construction and Other
+Important Internal Parts.]
+
+
+CAM-SHAFT AND CRANK-SHAFT DESIGN
+
+Before going extensively into the subject of crank-shaft construction it
+will be well to consider cam-shaft design, which is properly a part of
+the valve system and which has been considered in connection with the
+other elements which have to do directly with cylinder construction to
+some extent. Cam-shafts are usually simple members carried at the base
+of the cylinder in the engine case of Vee type motors by suitable
+bearings and having the cams employed to lift the valves attached at
+intervals. A typical cam-shaft design is shown at Fig. 133. Two main
+methods of cam-shaft construction are followed--that in which the cams
+are separate members, keyed and pinned to the shaft, and the other where
+the cams are formed integral, the latter being the most suitable for
+airplane engine requirements.
+
+[Illustration: Fig. 133.--Typical Cam-Shaft, with Valve Lifting Cams and
+Gears to Operate Auxiliary Devices Forged Integrally.]
+
+The cam-shafts shown at Figs. 133 and 134, B, are of the latter type, as
+the cams are machined integrally. In this case not only the cams but
+also the gears used in driving the auxiliary shafts are forged integral.
+This is a more expensive construction, because of the high initial cost
+of forging dies as well as the greater expense of machining. It has the
+advantage over the other form in which the cams are keyed in place in
+that it is stronger, and as the cams are a part of the shaft they can
+never become loose, as might be possible where they are separately
+formed and assembled on a simple shaft.
+
+[Illustration: Fig. 134.--Important Parts of Duesenberg Aviation Engine.
+A--Three Main Bearing Crank-Shaft. B--Cam-Shaft with Integral Cams.
+C--Piston and Connecting Rod Assembly. D--Valve Rocker Group. E--Piston.
+F--Main Bearing Brasses.]
+
+The importance of the crank-shaft has been previously considered, and
+some of its forms have been shown in views of the motors presented in
+earlier portions of this work. The crank-shaft is one of the parts
+subjected to the greatest strain and extreme care is needed in its
+construction and design, because practically the entire duty of
+transmitting the power generated by the motor to the gearset devolves
+upon it. Crank-shafts are usually made of high tensile strength steel of
+special composition. They may be made in four ways, the most common
+being from a drop or machine forging which is formed approximately to
+the shape of the finished shaft and in rare instances (experimental
+motors only) they may be steel castings. Sometimes they are made from
+machine forgings, where considerably more machine work is necessary than
+would be the case where the shaft is formed between dies. Some engineers
+favor blocking the shaft out of a solid slab of metal and then machining
+this rough blank to form. In some radial-cylinder motors of the Gnome
+and Le Rhone type the crank-shafts are built up of two pieces, held
+together by taper fastenings or bolts.
+
+[Illustration: Fig. 135.--Showing Method of Making Crank-Shaft. A--The
+Rough Steel Forging Before Machining. B--The Finished Six-Throw,
+Seven-Bearing Crank-Shaft.]
+
+The form of the shaft depends on the number of cylinders and the form
+has material influence on the method of construction. For instance, a
+four-cylinder crank-shaft could be made by either of the methods
+outlined. On the other hand, a three- or six-cylinder shaft is best made
+by the machine forging process, because if drop forged or cut from the
+blank it will have to be heated and the crank throws bent around so that
+the pins will lie in three planes one hundred and twenty degrees apart,
+while the other types described need no further attention, as the
+crank-pins lie in planes one hundred and eighty degrees apart. This can
+be better understood by referring to Fig. 135, which shows a
+six-cylinder shaft in the rough and finished stages. At A the
+appearance of the machine forging before any of the material is removed
+is shown, while at B the appearance of the finished crank-shaft is
+clearly depicted. The built-up crank-shaft is seldom used on
+multiple-cylinder motors, except in some cases where the crank-shafts
+revolve on ball bearings as in some automobile racing engines.
+
+[Illustration: Fig. 136.--Showing Form of Crank-Shaft for Twin-Cylinder
+Opposed Power Plant.]
+
+[Illustration: Fig. 137.--Crank-Shaft of Thomas-Morse Eight-Cylinder Vee
+Engine.]
+
+Crank-shaft form will vary with a number of cylinders and it is possible
+to use a number of different arrangements of crank-pins and bearings for
+the same number of cylinders. The simplest form of crank-shaft is that
+used on simple radial cylinder motors as it would consist of but one
+crank-pin, two webs, and the crank-shaft. As the number of cylinders
+increase in Vee motors as a general rule more crank-pins are used. The
+crank-shaft that would be used on a two-cylinder opposed motor is shown
+at Fig. 136. This has two throws and the crank-pins are spaced 180
+degrees apart. The bearings are exceptionally long. Four-cylinder
+crank-shafts may have two, three or five main bearings and three or four
+crank-pins. In some forms of two-bearing crank-shafts, such as used when
+four-cylinders are cast in a block, or unit casting, two of the pistons
+are attached to one common crank-pin, so that in reality the crank-shaft
+has but three crank-pins. A typical three bearing, four-cylinder
+crank-shaft is shown at Fig. 134, A. The same type can be used for an
+eight-cylinder Vee engine, except for the greater length of crank-pins
+to permit of side by side rods as shown at Fig. 137. Six cylinder
+vertical tandem and twelve-cylinder Vee engine crank-shafts usually have
+four or seven main bearings depending upon the disposition of the
+crank-pins and arrangement of cylinders. At Fig. 138, A, the bottom
+view of a twelve-cylinder engine with bottom half of crank case removed
+is given. This illustrates clearly the arrangement of main bearings when
+the crank-shaft is supported on four journals. The crank-shaft shown at
+Fig. 138, B, is a twelve-cylinder seven-bearing type.
+
+[Illustration: Fig. 138.--Crank-Case and Crank-Shaft Construction for
+Twelve-Cylinder Motors. A--Duesenberg. B--Curtiss.]
+
+[Illustration: Fig. 139.--Counterbalanced Crank-Shafts Reduce Engine
+Vibration and Permit of Higher Rotative Speeds.]
+
+In some automobile engines, extremely good results have been secured in
+obtaining steady running with minimum vibration by counterbalancing the
+crank-shafts as outlined at Fig. 139. The shaft at A is a type suitable
+for a high speed four-cylinder vertical or an eight-cylinder Vee type.
+That at B is for a six-cylinder vertical or a twelve-cylinder V with
+scissors joint rods. If counterbalancing crank-shafts helps in an
+automobile engine, it should have advantages of some moment in airplane
+engines, even though the crank-shaft weight is greater.
+
+
+BALL-BEARING CRANK-SHAFTS
+
+While crank-shafts are usually supported in plain journals there seems
+to be a growing tendency of late to use anti-friction bearings of the
+ball type for their support. This is especially noticeable on block
+motors where but two main bearings are utilized. When ball bearings are
+selected with proper relation to the load which obtains they will give
+very satisfactory service. They permit the crank-shaft to turn with
+minimum friction, and if properly selected will never need adjustment.
+The front end is supported by a bearing which is clamped in such a
+manner that it will take a certain amount of load in a direction
+parallel to the axis of the shaft, while the rear end is so supported
+that the outer race of the bearing has a certain amount of axial freedom
+or "float." The inner race or cone of each bearing is firmly clamped
+against shoulders on the crank-shaft. At the front end of the
+crank-shaft timing gear and a suitable check nut are used, while at the
+back end the bearing is clamped by a threaded retention member between
+the fly-wheel and a shoulder on the crank-shaft. The fly-wheel is held
+in place by a taper and key retention. The ball bearings are carried in
+a light housing of bronze or malleable iron, which in turn are held in
+the crank-case by bolts. The Renault engine uses ball bearings at front
+and rear ends of the crank-shaft, but has plain bearings around
+intermediate crank-shaft journals. The rotary engines of the Gnome, Le
+Rhone and Clerget forms would not be practical if ball bearings were not
+used as the bearing friction and consequent depreciation would be very
+high.
+
+
+ENGINE-BASE CONSTRUCTION
+
+One of the important parts of the power plant is the substantial casing
+or bed member, which is employed to support the cylinders and
+crank-shaft and which is attached directly to the fuselage engine
+supporting members. This will vary widely in form, but as a general
+thing it is an approximately cylindrical member which may be divided
+either vertically or horizontally in two or more parts. Airplane engine
+crank-cases are usually made of aluminum, a material which has about the
+same strength as cast iron, but which only weighs a third as much. In
+rare cases cast iron is employed, but is not favored by most engineers
+because of its brittle nature, great weight and low resistance to
+tensile stresses. Where exceptional strength is needed alloys of bronze
+may be used, and in some cases where engines are produced in large
+quantities a portion of the crank-case may be a sheet steel or aluminum
+stamping.
+
+[Illustration: Fig. 140.--View of Thomas 135 Horse-Power Aeromotor,
+Model 8, Showing Conventional Method of Crank-Case Construction.]
+
+[Illustration: Fig. 141.--Views of Upper Half of Thomas Aeromotor
+Crank-Case.]
+
+Crank-cases are always large enough to permit the crank-shaft and parts
+attached to it to turn inside and obviously its length is determined by
+the number of cylinders and their disposition. The crank-case of the
+radial cylinder or double-opposed cylinder engine would be substantially
+the same in length. That of a four-cylinder will vary in length with
+the method of casting the cylinder. When the four-cylinders are cast in
+one unit and a two-bearing crank-shaft is used, the crank-case is a very
+compact and short member. When a three-bearing crank-shaft is utilized
+and the cylinders are cast in pairs, the engine base is longer than it
+would be to support a block casting, but is shorter than one designed to
+sustain individual cylinder castings and a five-bearing crank-shaft. It
+is now common construction to cast an oil container integral with the
+bottom of the engine base and to draw the lubricating oil from it by
+means of a pump, as shown at Fig. 140. The arms by which the motor is
+supported in the fuselage are substantial-ribbed members cast
+integrally with the upper half.
+
+[Illustration: Fig. 142.--Method of Constructing Eight-Cylinder Vee
+Engine, Possible if Aluminum Cylinder and Crank-Case Castings are Used.]
+
+[Illustration: Fig. 143.--Simple and Compact Crank-Case, Possible When
+Radial Cylinder Engine Design is Followed.]
+
+The approved method of crank-case construction favored by the majority
+of engineers is shown at the top of Fig. 141, bottom side up. The upper
+half not only forms a bed for the cylinder but is used to hold the
+crank-shaft as well. In the illustration, the three-bearing boxes form
+part of the case, while the lower brasses are in the form of separately
+cast caps retained by suitable bolts. In the construction outlined the
+bottom part of the case serves merely as an oil container and a
+protection for the interior mechanism of the motor. The cylinders are
+held down by means of studs screwed into the crank-case top, as shown at
+Fig. 141, lower view. If the aluminum cylinder motor has any future, the
+method of construction outlined at Fig. 142, which has been used in cast
+iron for an automobile motor, might be used for an eight-cylinder Vee
+engine for airplane use. The simplicity of the crank-case needed for a
+revolving cylinder motor and its small weight can be well understood by
+examination of the illustration at Fig. 143, which shows the engine
+crank-case for the nine-cylinder "Monosoupape" Gnome engine. This
+consists of two accurately machined forgings held together by bolts as
+clearly indicated.
+
+
+
+
+CHAPTER X
+
+    Power Plant Installation--Curtiss OX-2 Engine Mounting and
+    Operating Rules--Standard S. A. E. Engine Bed Dimensions--
+    Hall-Scott Engine Installation and Operation--Fuel System Rules
+    --Ignition System--Water System--Preparations to Start Engine--
+    Mounting Radial and Rotary Engines--Practical Hints to Locate
+    Engine Troubles--All Engine Troubles Summarized--Location of
+    Engine Troubles Made Easy.
+
+
+The proper installation of the airplane power plant is more important
+than is generally supposed, as while these engines are usually well
+balanced and run with little vibration, it is necessary that they be
+securely anchored and that various connections to the auxiliary parts be
+carefully made in order to prevent breakage from vibration and that
+attendant risk of motor stoppage while in the air. The type of motor to
+be installed determines the method of installation to be followed. As a
+general rule six-cylinder vertical engine and eight-cylinder Vee type
+are mounted in substantially the same way. The radial, fixed cylinder
+forms and the radial, rotary cylinder Gnome and Le Rhone rotary types
+require an entirely different method of mounting. Some unconventional
+mountings have been devised, notably that shown at Fig. 144, which is a
+six-cylinder German engine that is installed in just the opposite way to
+that commonly followed. The inverted cylinder construction is not
+generally followed because even with pressure feed, dry crank-case type
+lubricating system there is considerable danger of over-lubrication and
+of oil collecting and carbonizing in the combustion chamber and gumming
+up the valve action much quicker than would be the case if the engine
+was operated in the conventional upright position. The reason for
+mounting an engine in this way is to obtain a lower center of gravity
+and also to make for more perfect streamlining of the front end of the
+fuselage in some cases. It is rather doubtful if this slight advantage
+will compensate for the disadvantages introduced by this unusual
+construction. It is not used to any extent now but is presented merely
+to show one of the possible systems of installing an airplane engine.
+
+[Illustration: Fig. 144.--Unconventional Mounting of German Inverted
+Cylinder Motor.]
+
+[Illustration: Fig. 145.--How Curtiss Model OX-2 Motor is Installed in
+Fuselage of Curtiss Tractor Biplane. Note Similarity of Mounting to
+Automobile Power Plant.]
+
+In a number of airplanes of the tractor-biplane type the power plant
+installation is not very much different than that which is found in
+automobile practice. The illustration at Fig. 145 is a very clear
+representation of the method of mounting the Curtiss eight-cylinder 90
+H. P. or model OX-2 engine in the fuselage of the Curtiss JN-4 tractor
+biplane which is so generally used in the United States as a training
+machine. It will be observed that the fuel tank is mounted under a cowl
+directly behind the motor and that it feeds the carburetor by means of
+a flexible fuel pipe. As the tank is mounted higher than the
+carburetor, it will feed that member by gravity. The radiator is mounted
+at the front end of the fuselage and connected to the water piping on
+the motor by the usual rubber hose connections. An oil pan is placed
+under the engine and the top is covered with a hood just as in motor car
+practice. The panels of aluminum are attached to the sides of the
+fuselage and are supplied with doors which open and provide access to
+the carburetor, oil-gauge and other parts of the motor requiring
+inspection. The complete installation with the power plant enclosed is
+given at Fig. 146, and in this it will be observed that the exhaust
+pipes are connected to discharge members that lead the gases above the
+top plane. In the engine shown at Fig. 145 the exhaust flows directly
+into the air at the sides of the machine through short pipes bolted to
+the exhaust gas outlet ports. The installation of the radiator just
+back of the tractor screw insures that adequate cooling will be obtained
+because of the rapid air flow due to the propeller slip stream.
+
+[Illustration: Fig. 146.--Latest Model of Curtiss JN-4 Training Machine,
+Showing Thorough Enclosure of Power Plant and Method of Disposing of the
+Exhaust Gases.]
+
+
+INSTALLATION OF CURTISS OX-2 ENGINE
+
+[Illustration: Fig. 147.--Front View of L. W. F. Tractor Biplane
+Fuselage, Showing Method of Installing Thomas Aeromotor and Method of
+Disposing of Exhaust Gases.]
+
+The following instructions are given in the Curtiss Instruction Book for
+installing the OX-2 engine and preparing it for flights, and taken in
+connection with the very clear illustration presented no difficulty
+should be experienced in understanding the proper installation, and
+mounting of this power plant. The bearers or beds should be 2 inches
+wide by 3 inches deep, preferably of laminated hard wood, and placed
+11-5/8 inches apart. They must be well braced. The six arms of the base
+of the motor are drilled for 3/8-inch bolts, and none but this size
+should he used.
+
+1. _Anchoring the Motor._ Put the bolts in from the bottom, with a large
+washer under the head of each so the head cannot cut into the wood. On
+every bolt use a castellated nut and a cotter pin, or an ordinary nut
+and a lock washer, so the bolt will not work loose. Always set motor in
+place and fasten before attaching any auxiliary apparatus, such as
+carburetor, etc.
+
+2. _Inspecting the Ignition-Switch Wires._ The wires leading from the
+ignition switch must be properly connected--one end to the motor body
+for ground, and the other end to the post on the breaker box of the
+magneto.
+
+3. _Filling the Radiator._ Be sure that the water from the radiator
+fills the cylinder jackets. Pockets of air may remain in the cylinder
+jackets even though the radiator may appear full. Turn the motor over a
+few times by hand after filling the radiator, and then add more water if
+the radiator will take it. The air pockets, if allowed to remain, may
+cause overheating and develop serious trouble when the motor is running.
+
+4. _Filling the Oil Reservoir._ Oil is admitted into the crank-case
+through the breather tube at the rear. It is well to strain all oil put
+into the crank-case. In filling the oil reservoir be sure to turn the
+handle on the oil sight-gauge till it is at right angles with the gauge.
+The oil sight-gauge is on the side of the lower half of the crank-case.
+Put in about 3 gallons of the best obtainable oil, Mobile B recommended.
+It is important to remember that the very best oil is none too good.
+
+5. _Oiling Exposed Moving Parts._ Oil all rocker-arm bearings before
+each flight. A little oil should be applied where the push rods pass
+through the stirrup straps.
+
+6. _Filling the Gasoline Tanks._ Be certain that all connections in the
+gasoline system are tight.
+
+7. _Turning on the Gasoline._ Open the cock leading from the gasoline
+tank to the carburetor.
+
+8. _Charging the Cylinders._ With the ignition switch OFF, prime the
+motor by squirting a little gasoline in each exhaust port and then turn
+the propeller backward two revolutions. Never open the exhaust valve by
+operating the rocker-arm by hand, as the push-rod is liable to come out
+of its socket in the cam follower and bend the rocker-arm when the motor
+turns over.
+
+9. _Starting the Motor by Hand._ Always retard the spark part way, to
+prevent back-firing, by pulling forward the wire attached to the breaker
+box. Failure to so retard the spark in starting may result in serious
+injury to the operator. Turn on the ignition switch with throttle partly
+open; give a quick, strong pull down and outward on the starting crank
+or propeller. As soon as the motor is started advance the spark by
+releasing the retard wire.
+
+10. _Oil Circulation._ Let the motor run at low speed for a few minutes
+in order to establish oil circulation in all bearings. With all parts
+functioning properly, the throttle may be opened gradually for warming
+up before flight.
+
+
+STANDARD S.A.E. ENGINE BED DIMENSIONS
+
+The Society of Automotive Engineers have made efforts to standardize
+dimensions of bed timbers for supporting power plant in an aeroplane.
+Owing to the great difference in length no standardization is thought
+possible in this regard. The dimensions recommended are as follows:
+
+  Distance between timbers           12     in.   14     in.   16 in.
+  Width of bed timbers                1-1/2 in.    1-3/4 in.    2 in.
+  Distance between centers of bolts  13-1/2 in.   15-3/4 in.   18 in.
+
+It will be evident that if any standard of this nature were adopted by
+engine builders that the designers of fuselage could easily arrange
+their bed timbers to conform to these dimensions, whereas it would be
+difficult to have them adhere to any standard longitudinal dimensions
+which are much more easily varied in fuselages than the transverse
+dimensions are. It, however, should be possible to standardize the
+longitudinal positions of the holding down bolts as the engine designer
+would still be able to allow himself considerable space fore-and-aft of
+the bolts.
+
+[Illustration: Fig. 148.--End Elevation of Hall-Scott A-7 Four-Cylinder
+Motor, with Installation Dimensions.]
+
+
+HALL-SCOTT ENGINE INSTALLATION
+
+[Illustration: Fig. 149.--Plan and Side Elevation of Hall-Scott A-7
+Four-Cylinder Airplane Engine, with Installation Dimensions.]
+
+The very thorough manner in which installation diagrams are prepared by
+the leading engine makers leaves nothing to the imagination. The
+dimensions of the Hall-Scott four-cylinder airplane engine are given
+clearly in our inch measurements with the metric equivalents at Figs.
+148 and 149, the former showing a vertical elevation while the latter
+has a plan view and side elevation. The installation of this engine in
+airplanes is clearly shown at Figs. 150 and 151, the former having the
+radiator installed at the front of the motor and having all exhaust
+pipes joined to one common discharge funnel, which deflects the gas over
+the top plane while the latter has the radiator placed vertically above
+the motor at the back end and has a direct exhaust gas discharge to the
+air.
+
+[Illustration: Fig. 150.
+
+CENSORED]
+
+[Illustration: Fig. 151.
+
+CENSORED]
+
+The dimensions of the six-cylinder Hall-Scott motor which is known as
+the type A-5 125 H. P. are given at Fig. 152, which is an end sectional
+elevation, and at Fig. 153, which is a plan view. The dimensions are
+given both in inch sizes and the metric equivalents. The appearance of
+a Hall-Scott six-cylinder engine installed in a fuselage is given at
+Fig. 154, while a diagram showing the location of the engine and the
+various pipes leading to the auxiliary groups is outlined at Fig. 155.
+The following instructions for installing the Hall-Scott power plant
+are reproduced from the instruction book issued by the maker.
+Operating instructions which are given should enable any good mechanic
+to make a proper installation and to keep the engine in good running
+condition.
+
+[Illustration: Fig. 152.
+
+CENSORED]
+
+
+FUEL SYSTEM INSTALLATION
+
+[Illustration: Fig. 153.--Plan View of Hall-Scott Type A-5 125
+Horse-Power Airplane Engine, Showing Installation Dimensions.]
+
+Gasoline giving the best results with this equipment is as follows:
+Gravity 58-62 deg. Baume A. Initial boiling point--Richmond method--102
+deg. Fahr. Sulphur .014. Calorimetric bomb test 20610 B. T. U. per pound.
+If the gasoline tank is placed in the fuselage below the level of the
+carburetor, a hand pump must be used to maintain air pressure in gas
+tank to force the gasoline to the carburetor. After starting the engine
+the small auxiliary air pump upon the engine will maintain sufficient
+pressure. A-7a and A-5a engines are furnished with a new type auxiliary
+air pump. This should be frequently oiled and care taken so no grit or
+sand will enter which might lodge between the valve and its seat, which
+would make it fail to operate properly. An air relief valve is furnished
+with each engine. It should be screwed into the gas tank and properly
+regulated to maintain the pressure required. This is done by screwing
+the ratchet on top either up or down. If two tanks are used in a plane
+one should be installed in each tank. All air pump lines should be
+carefully gone over quite frequently to ascertain if they are tight.
+Check valves have to be placed in these lines. In some cases the
+gasoline tank is placed above the engine, allowing it to drain by
+gravity to the carburetor. When using this system there should be a drop
+of not less than two feet from the lowest portion of the gasoline tank
+to the upper part of the carburetor float chamber. Even this height
+might not be sufficient to maintain the proper volume of gasoline to the
+carburetor at high speeds. Air pressure is advised upon all tanks to
+insure the proper supply of gasoline. When using gravity feed without
+air pressure be sure to vent the tank to allow circulation of air. If
+gravity tank is used and the engine runs satisfactorily at low speeds
+but cuts out at high speeds the trouble is undoubtedly due to
+insufficient height of the tank above the carburetor. The tank should be
+raised or air pressure system used.
+
+[Illustration: Fig. 154.--Three-Quarter View of Hall-Scott Type A-5 125
+Horse-Power Six-Cylinder Engine, with One of the Side Radiators Removed
+to Show Installation in Standard Fuselage.]
+
+[Illustration: Fig. 155.--Diagram Showing Proper Installation of
+Hall-Scott Type A-5 125 Horse-Power Engine with Pressure Feed Fuel
+Supply System.]
+
+
+IGNITION SWITCHES
+
+Two "DIXIE" switches are furnished with each engine. Both of these
+should be installed in the pilot's seat, one controlling the R. H., and
+the other the L. H. magneto. By shorting either one or the other it can
+be quickly determined if both magnetos, with their respective
+spark-plugs, are working correctly. Care should be taken not to use
+spark-plugs having _special extensions or long protruding points_. Plugs
+giving best results are extremely small with short points.
+
+
+WATER SYSTEMS
+
+A temperature gauge should be installed in the water pipe, coming
+directly from the cylinder nearest the propeller (note illustration
+above). This instrument installed in the radiator cap has not always
+given satisfactory results. This is especially noticeable when the water
+in the radiator becomes low, not allowing it to touch the bulb on the
+moto-meter. For ordinary running, it should not indicate over 150
+degrees Fahr. In climbing tests, however, a temperature of 160 degrees
+Fahr. can be maintained without any ill effects upon the engine. In case
+the engine becomes overheated, the indicator will register above 180
+degrees Fahr., in which case it should be stopped immediately.
+Overheating is most generally caused by retarded spark, excessive carbon
+in the cylinders, insufficient lubrication, improperly timed valves,
+lack of water, clogging of water system in any way which would obstruct
+the free circulation of the water.
+
+Overheating will cause the engine to knock, with possible damaging
+results. Suction pipes should be made out of thin tubing, and run within
+a quarter or an eighth of an inch of each other, so that when a hose is
+placed over the two, it will not be possible to suck together. This is
+often the case when a long rubber hose is used, which causes
+overheating. Radiators should be flushed out and cleaned thoroughly
+quite often. A dirty radiator may cause overheating.
+
+When filling the radiator it is very important to remove the plug on top
+of the water pump until water appears. This is to avoid air pockets
+being formed in the circulating system, which might not only heat up the
+engine, but cause considerable damage. All water pump hoses and
+connections should be tightly taped and shellacked after the engine is
+properly installed in the plane. The greatest care should be taken when
+making engine installation _not_ to use smaller inside diameter hose
+connection than water pump suction end casting. One inch and a quarter
+inside diameter should be used on A-7 and A-5 motors, while nothing less
+than one inch and a half inside diameter hose or tubing on all A-7a and
+A-5a engines. It is further important to have light spun tubing, void of
+any sharp turns, leads from pump to radiator and cylinder water outlet
+to radiator. In other words, the water circulation through the engine
+must be as little restricted as possible. Be sure no light hose is used,
+that will often suck together when engine is started. To thoroughly
+drain the water from the entire system, open the drain cock at the
+lowest side of the water pump.
+
+
+PREPARATIONS TO START ENGINE
+
+Always replenish gasoline tanks through a strainer which is clean. This
+strainer must catch all water and other impurities in the gasoline. Pour
+at least three gallons of fresh oil into the lower crank-case. Oil all
+rocker arms through oilers upon rocker arm housing caps. Be sure
+radiators are filled within one inch of the top.
+
+After all the parts are oiled, and the tanks filled, the following must
+be looked after before starting: See if crank-shaft flange is tight on
+shaft. See if propeller bolts are tight and evenly drawn up. See if
+propeller bolts are wired. See if propeller is trued up to within 1/8".
+
+Every four days the magnetos should be oiled if the engine is in daily
+use.
+
+Every month all cylinder hold-down nuts should be gone over to ascertain
+if they are tight. (Be sure to recotter nuts.)
+
+See if magnetos are bolted on tight and wired.
+
+See if magneto cables are in good condition.
+
+See if rocker arm tappets have a .020" clearance from valve stem when
+valve is seated.
+
+See if tappet clamp screws are tight and cottered.
+
+See if all gasoline, oil, water pipes and connections are in perfect
+condition.
+
+Air on gas line should be tested for leaks.
+
+Pump at least three pounds air pressure into gasoline tank.
+
+After making sure that above rules have been observed, test compression
+of cylinders by turning propeller.
+
+"DO NOT FORGET TO SHORT BOTH MAGNETOS"
+
+Be sure all compression release and priming cocks do not leak
+compression. If they do, replace same with a new one immediately, as
+this might cause premature firing.
+
+Open priming cocks and squirt some gasoline into each.
+
+Close cocks.
+
+Open compression release cocks.
+
+Open throttle slightly.
+
+If using Berling magnetos they should be three-quarters advanced.
+
+If all the foregoing directions have been carefully followed, the engine
+is ready for starting.
+
+In cranking engine either by starting crank, or propeller, it is
+essential to throw it over compression quickly.
+
+Immediately upon starting, close compression release cocks.
+
+When engine is running, advance magnetos.
+
+After it has warmed up, short one magneto and then the other, to be sure
+both magnetos and spark-plugs are firing properly. If there is a miss,
+the fouled plug must be located and cleaned. There is a possibility that
+the jets in the carburetor are stopped up. If this is the case, do not
+attempt to clean same with any sharp instrument. If this is done, it
+might change the opening in the jets, thus spoiling the adjustment. Jets
+and nozzles should be blown out with air or steam.
+
+An open intake or exhaust valve, which might have become sluggish or
+stuck from carbon, might cause trouble. Be sure to remedy this at once
+by using a little coal-oil or kerosene on same, working the valve by
+hand until it becomes free. We recommend using graphite on valve stems
+mixed with oil to guard against sticking or undue wear.
+
+
+INSTALLING ROTARY AND RADIAL CYLINDER ENGINES
+
+[Illustration: Fig. 156.--Diagram Defining Installation of Gnome
+"Monosoupape" Motor in Tractor Biplane. Note Necessary Piping for Fuel,
+Oil, and Air Lines.]
+
+When rotary engines are installed simple steel stamping or "spiders,"
+are attached to the fuselage to hold the fixed crank-shaft. Inasmuch as
+the motor projects clear of the fuselage proper there is plenty of room
+back of the front spider plate to install the auxiliary parts such as
+the oil pump, air pump and ignition magneto and also the fuel and oil
+containers. The diagram given at Fig. 156 shows how a Gnome
+"monosoupape" engine is installed on the anchorage plates and it also
+outlines clearly the piping necessary to convey the oil and fuel and
+also the air-piping needed to put pressure on both fuel and oil tanks to
+insure positive supply of these liquids which may be carried in tanks
+placed lower than the motor in some installations. The diagram given at
+Figs. 157 and 158 shows other mountings of Gnome engines and are
+self-explanatory. The simple mounting possible when the Anzani
+ten-cylinder radial fixed type engine is used given at Fig. 159. The
+front end of the fuselage is provided with a substantial pressed steel
+plate having members projecting from it which may be bolted to the
+longerons. The bolts that hold the two halves of the crank-case together
+project through the steel plate and hold the engine securely to the
+front end of the fuselage.
+
+[Illustration: Fig. 157.--Showing Two Methods of Placing Propeller on
+Gnome Rotary Motor.]
+
+
+PRACTICAL HINTS TO LOCATE ENGINE TROUBLES
+
+[Illustration: Fig. 158.--How Gnome Rotary Motor May Be Attached to
+Airplane Fuselage Members.]
+
+One who is not thoroughly familiar with engine construction will seldom
+locate troubles by haphazard experimenting and it is only by a
+systematic search that the cause can be discovered and the defects
+eliminated. In this chapter the writer proposes to outline some of the
+most common power-plant troubles and to give sufficient advice to enable
+those who are not thoroughly informed to locate them by a logical
+process of elimination. The internal-combustion motor, which is the
+power plant of all gasoline automobiles as well as airplanes, is
+composed of a number of distinct groups, which in turn include distinct
+components. These various appliances are so closely related to each
+other that defective action of any one may interrupt the operation of
+the entire power plant. Some of the auxiliary groups are more necessary
+than others and the power plant will continue to operate for a time even
+after the failure of some important parts of some of the auxiliary
+groups. The gasoline engine in itself is a complete mechanism, but it
+is evident that it cannot deliver any power without some means of
+supplying gas to the cylinders and igniting the compressed gas charge
+after it has been compressed in the cylinders. From this it is patent
+that the ignition and carburetion systems are just as essential parts of
+the power plant as the piston, connecting rod, or cylinder of the motor.
+The failure of either the carburetor or igniting means to function
+properly will be immediately apparent by faulty action of the power
+plant.
+
+[Illustration: Fig. 159.--How Anzani Ten-Cylinder Radial Engine is
+Installed to Plate Securely Attached to Front End of Tractor Airplane
+Fuselage.]
+
+To insure that the motor will continue to operate it is necessary to
+keep it from overheating by some form of cooling system and to supply
+oil to the moving parts to reduce friction. The cooling and lubrication
+groups are not so important as carburetion and ignition, as the engine
+would run for a limited period of time even should the cooling system
+fail or the oil supply cease. It would only be a few moments, however,
+before the engine would overheat if the cooling system was at fault, and
+the parts seize if the lubricating system should fail. Any derangement
+in the carburetor or ignition mechanism would manifest itself at once
+because the engine operation would be affected, but a defect in the
+cooling or oiling system would not be noticed so readily.
+
+The careful aviator will always inspect the motor mechanism before
+starting on a trip of any consequence, and if inspection is carefully
+carried out and loose parts tightened it is seldom that irregular
+operation will be found due to actual breakage of any of the components
+of the mechanism. Deterioration due to natural causes matures slowly,
+and sufficient warning is always given when parts begin to wear so
+satisfactory repairs may be promptly made before serious derangement or
+failure is manifested.
+
+
+A TYPICAL ENGINE STOPPAGE ANALYZED
+
+Before describing the points that may fail in the various auxiliary
+systems it will be well to assume a typical case of engine failure and
+show the process of locating the trouble in a systematic manner by
+indicating the various steps which are in logical order and which could
+reasonably be followed. In any case of engine failure the ignition
+system, motor compression, and carburetor should be tested first. If the
+ignition system is functioning properly one should determine the amount
+of compression in all cylinders and if this is satisfactory the
+carbureting group should be tested. If the ignition system is working
+properly and there is a decided resistance in the cylinders when the
+propeller is turned, proving that there is good compression, one may
+suspect the carburetor.
+
+[Illustration: Fig. 160.--Side Elevation of Thomas 135 Horse-Power
+Airplane Engine, Giving Important Dimensions.]
+
+If the carburetor appears to be in good condition, the trouble may be
+caused by the ignition being out of time, which condition is possible
+when the magneto timing gear or coupling is attached to the armature
+shaft by a taper and nut retention instead of the more positive key or
+taper-pin fastening. It is possible that the inlet manifold may be
+broken or perforated, that the exhaust valve is stuck on its seat
+because of a broken or bent stem, broken or loose cam, or failure of the
+cam-shaft drive because the teeth are stripped from the engine shaft or
+cam-shaft gears; or because the key or other fastening on either gear
+has failed, allowing that member to turn independently of the shaft to
+which it normally is attached. The gasoline feed pipe may be clogged or
+broken, the fuel supply may be depleted, or the shut-off cock in the
+gasoline line may have jarred closed. The gasoline filter may be filled
+with dirt or water which prevents passage of the fuel.
+
+[Illustration: Fig. 161.--Front Elevation of Thomas-Morse 135
+Horse-Power Aeromotor, Showing Main Dimensions.]
+
+The defects outlined above, except the failure of the gasoline supply,
+are very rare, and if the container is found to contain fuel and the
+pipe line to be clear to the carburetor, it is safe to assume the
+vaporizing device is at fault. If fuel continually runs out of the
+mixing chamber the carburetor is said to be flooded. This condition
+results from failure of the shut-off needle to seat properly or from a
+punctured hollow metal float or a gasoline-soaked cork float. It is
+possible that not enough gasoline is present in the float chamber. If
+the passage controlled by the float-needle valve is clogged or if the
+float was badly out of adjustment, this contingency would be probable.
+When the carburetor is examined, if the gasoline level appears to be at
+the proper height, one may suspect that a particle of lint, or dust, or
+fine scale, or rust from the gasoline tank has clogged the bore of the
+jet in the mixing chamber.
+
+If the ignition system and carburetor appear to be in good working
+order, and the hand crank shows that there is no compression in one or
+more of the cylinders, it means some defect in the valve system. If the
+engine is a multiple-cylinder type and one finds poor compression in all
+of the cylinders it may be due to the rare defect of improper valve
+timing. This may be caused by a gear having altered its position on the
+cam-shaft or crank-shaft, because of a sheared key or pin having
+permitted the gear to turn about half of a revolution and then having
+caught and held the gear in place by a broken or jagged end so that
+cam-shaft would turn, but the valves open at the wrong time. If but one
+of the cylinders is at fault and the rest appear to have good
+compression the trouble may be due to a defective condition either
+inside or outside of that cylinder. The external parts may be inspected
+easily, so the following should be looked for: a broken valve, a warped
+valve-head, broken valve-springs, sticking or bent valve-stems, dirt
+under valve-seat, leak at valve-chamber cap or spark-plug gasket.
+Defective priming cock, cracked cylinder head (rarely occurs), leak
+through cracked spark-plug insulation, valve-plunger stuck in the
+guide, lack of clearance between valve-stem end and top of plunger
+caused by loose adjusting screw which has worked up and kept the valve
+from seating. The faulty compression may be due to defects inside the
+motor. The piston-head may be cracked (rarely occurs), piston rings may
+be broken, the slots in the piston rings may be in line, the rings may
+have lost their elasticity or have become gummed in the grooves of the
+piston, or the piston and cylinder walls may be badly scored by a loose
+wrist pin or by defective lubrication. If the motor is a type with a
+separate head it is possible the gasket or packing between the cylinder
+and combustion chamber may leak, either admitting water to the cylinder
+or allowing compression to escape.
+
+[Illustration: Fig. 162.--Front and Side Elevations of Sturtevant
+Airplane Engine, Giving Principal Dimensions to Facilitate
+Installation.]
+
+
+CONDITIONS THAT CAUSE FAILURE OF IGNITION SYSTEM
+
+If the first test of the motor had showed that the compression was as it
+should be and that there were no serious mechanical defects and there
+was plenty of gasoline at the carburetor, this would have demonstrated
+that the ignition system was not functioning properly. If a battery is
+employed to supply current the first step is to take the spark-plugs out
+of the cylinders and test the system by turning over the engine by hand.
+If there is no spark in any of the plugs, this may be considered a
+positive indication that there is a broken main current lead from the
+battery, a defective ground connection, a loose battery terminal, or a
+broken connector. If none of these conditions are present, it is safe to
+say that the battery is no longer capable of delivering current. While
+magneto ignition is generally used on airplane engines, there is apt to
+be some development of battery ignition, especially on engines equipped
+with electric self-starters which are now being experimented with. The
+spark-plugs may be short circuited by cracked insulation or carbon and
+oil deposits around the electrode. The secondary wires may be broken or
+have defective insulation which permits the current to ground to some
+metal part of the fuselage or motor. The electrodes of the spark-plug
+may be too far apart to permit a spark to overcome the resistance of the
+compressed gas, even if a spark jumps the air space, when the plug is
+laid on the cylinder.
+
+If magnetos are fitted as is usually the case at present and a spark is
+obtained between the points of the plug and that device or the wire
+leading to it from the magneto is in proper condition, the trouble is
+probably caused by the magneto being out of time. This may result if the
+driving gear is loose on the armature-shaft or crank-shaft, and is a
+rare occurrence. If no spark is produced at the plugs the secondary wire
+may be broken, the ground wire may make contact with some metallic
+portion of the chassis before it reaches the switch, the carbon
+collecting brushes may be broken or not making contact, the contact
+points of the make-and-break device may be out of adjustment, the wiring
+may be attached to wrong terminals, the distributor filled with metallic
+particles, carbon, dust or oil accumulations, the distributor contacts
+may not be making proper connection because of wear and there may be a
+more serious derangement, such as a burned out secondary winding or a
+punctured condenser.
+
+If the motor runs intermittently, _i.e._, starts and runs only a few
+revolutions, aside from the conditions previously outlined, defective
+operation may be due to seizing between parts because of insufficient
+oil or deficient cooling, too much oil in the crank-case which fouls the
+cylinder after the crank-shaft has revolved a few turns, and
+derangements in the ignition or carburetion systems that may be easily
+remedied. There are a number of defective conditions which may exist in
+the ignition group, that will result in "skipping" or irregular
+operation and the following points should be considered first: weak
+source of current due to worn out dry cells or discharged storage
+batteries; weak magnets in magneto, or defective contacts at magneto;
+dirt in magneto distributor or poor contact at collecting brushes. Dirty
+or cracked insulator at spark-plug will cause short circuit and can
+only be detected by careful examination. The following points should
+also be checked over when the plug is inspected: Excessive space between
+electrodes, points too close together, loose central electrodes, or
+loose point on plug body, soot or oil particles between electrodes, or
+on the surface of the insulator, cracked insulator, oil or water on
+outside of insulator. Short circuits in the condenser or internal wiring
+of induction coils or magnetos, which are fortunately not common, can
+seldom be remedied except at the factory where these devices were made.
+If an engine stops suddenly and the defect is in the ignition system the
+trouble is usually never more serious than a broken or loose wire. This
+may be easily located by inspecting the wiring at the terminals.
+Irregular operation or misfiring is harder to locate because the trouble
+can only be found after the many possible defective conditions have been
+checked over, one by one.
+
+
+COMMON DEFECTS IN FUEL SYSTEMS
+
+Defective carburetion often causes misfiring or irregular operation. The
+common derangement of the components of the fuel system that are common
+enough to warrant suspicion and the best methods for their location
+follows: First, disconnect the feed pipe from the carburetor and see if
+the gasoline flows freely from the tank. If the stream coming out of the
+pipe is not the full size of the orifice it is an indication that the
+pipe is clogged with dirt or that there is an accumulation of rust,
+scale, or lint in the strainer screens of the filter. It is also
+possible that the fuel shut-off valve may be wholly or partly closed. If
+the gasoline flows by gravity the liquid may be air bound in the tank,
+while if a pressure-feed system is utilized the tank may leak so that it
+does not retain pressure; the check valve retaining the pressure may be
+defective or the pipe conveying the air or gas under pressure to the
+tank may be clogged.
+
+If the gasoline flows from the pipe in a steady stream the carburetor
+demands examination. There may be dirt or water in the float chamber,
+which will constrict the passage between the float chamber and the spray
+nozzle, or a particle of foreign matter may have entered the nozzle and
+stopped up the fine holes therein. The float may bind on its guide, the
+needle valve regulating the gasoline-inlet opening in bowl may stick to
+its seat. Any of the conditions mentioned would cut down the gasoline
+supply and the engine would not receive sufficient quantities of gas.
+The air-valve spring may be weak or the air valve broken. The
+gasoline-adjusting needle may be loose and jar out of adjustment, or the
+air-valve spring-adjusting nuts may be such a poor fit on the stem that
+adjustments will not be retained. These instructions apply only to
+carburetors having air valves and mixture regulating means which are
+used only in rare instances in airplane work. Air may leak in through
+the manifold, due to a porous casting, or leaky joints in a built up
+form and dilute the mixture. The air-intake dust screen may be so
+clogged with dirt and lint that not enough air will pass through the
+mesh. Water or sediment in the gasoline will cause misfiring because the
+fuel feed varies when the water or dirt constricts the standpipe bore.
+
+It is possible that the carburetor may be out of adjustment. If clouds
+of black smoke are emitted at the exhaust pipe it is positive indication
+that too much gasoline is being supplied the mixture and the supply
+should be cut down by screwing in the needle valve on types where this
+method of regulation is provided, and by making sure that the fuel level
+is at the proper height, or that the proper nozzle is used in those
+forms where the spray nozzle has no means of adjustment. If the mixture
+contains too much air there will be a pronounced popping back in the
+carburetor. This may be overcome by screwing in the air-valve adjustment
+so the spring tension is increased or by slightly opening up the
+gasoline-supply regulation needle. When a carburetor is properly
+adjusted and the mixture delivered the cylinder burns properly, the
+exhaust gas will be clean and free from the objectionable odor present
+when gasoline is burned in excess.
+
+The character of combustion may be judged by the color of the flame
+which issues from it when the engine is running with an open throttle
+after nightfall. If the flame is red, it indicates too much gasoline. If
+yellowish, it shows an excess of air, while a properly proportioned
+mixture will be evidenced by a pronounced blue flame, such as given by a
+gas-stove burner.
+
+The Duplex Model O. D. Zenith carburetor used upon most of the six- and
+eight-cylinder airplane engines consists of a single float chamber, and
+a single air intake, joined to two separate and distinct spray nozzles,
+venturi and idling adjustments. It is to be noted that as the carburetor
+barrels are arranged side by side, both valves are mounted on the same
+shaft, and work in unison through a single operating lever. It is not
+necessary to alter their position. In order to make the engine idle
+well, it is essential that the ignition, especially the spark-plugs,
+should be in good condition. The gaskets between carburetor and
+manifold, and between manifold and cylinders should be absolutely
+air-tight. The adjustment for low speed on the carburetor is made by
+turning in or out the two knurled screws, placed one on each side of the
+float chamber. After starting the engine and allowing it to become
+thoroughly warmed, one side of the carburetor should be adjusted so that
+the three cylinders it affects fire properly at low speed. The other
+side should be adjusted in the same manner until all six cylinders fire
+perfectly at low speed. As the adjustment is changed on the knurled
+screw a difference in the idling of the engine should be noticed. If the
+engine begins to run evenly or speeds up it shows that the mixture
+becomes right in its proportion.
+
+Be sure the butterfly throttle is closed as far as possible by screwing
+out the stop screw which regulates the closed position for idling. Care
+should be taken to have the butterfly held firmly against this stop
+screw at all times while idling engine. If three cylinders seem to run
+irregularly after changing the position of the butterfly, still another
+adjustment may have to be made with the knurled screw. Unscrewing this
+makes the mixture leaner. Screwing in closes off some of the air supply
+to the idling jet, making it richer. After one side has been made to
+idle satisfactorily repeat the same procedure with the opposite three
+cylinders. In other words, each side should be idled independently to
+about the same speed.
+
+Remember that the main jet and compensating jet have no appreciable
+effect on the idling of the engine. The idling mixture is drawn directly
+through the opening determined by the knurled screw and enters the
+carburetor barrel through the small hole at the edge of each butterfly.
+This is called the priming hole and is only effective during idling.
+Beyond that point the suction is transferred to the main jet and
+compensator, which controls the power of the engine beyond the idling
+position of the throttle.
+
+
+DEFECTS IN OILING SYSTEMS
+
+While troubles existing in the ignition or carburetion groups are
+usually denoted by imperfect operation of the motor, such as lost power,
+and misfiring, derangements of the lubrication or cooling systems are
+usually evident by overheating, diminution in engine capacity, or noisy
+operation. Overheating may be caused by poor carburetion as much as by
+deficient cooling or insufficient oiling. When the oiling group is not
+functioning as it should the friction between the motor parts produces
+heat. If the cooling system is in proper condition, as will be evidenced
+by the condition of the water in the radiator, and the carburetion group
+appears to be in good condition, the overheating is probably caused by
+some defect in the oiling system.
+
+The conditions that most commonly result in poor lubrication are:
+Insufficient oil in the engine crank-case or sump, broken or clogged oil
+pipes, screen at filter filled with lint or dirt, broken oil pump, or
+defective oil-pump drive. The supply of oil may be reduced by a
+defective inlet or discharge-check valve at the mechanical oiler or worn
+pumps. A clogged oil passage or pipe leading to an important bearing
+point will cause trouble because the oil cannot get between the working
+surfaces. It is well to remember that much of the trouble caused by
+defective oiling may be prevented by using only the best grades of
+lubricant, and even if all parts of the oil system are working properly,
+oils of poor quality will cause friction and overheating.
+
+
+DEFECTS IN COOLING SYSTEMS OUTLINED
+
+Cooling systems are very simple and are not liable to give trouble as a
+rule if the radiator is kept full of clean water and the circulation is
+not impeded. When overheating is due to defective cooling the most
+common troubles are those that impede water circulation. If the radiator
+is clogged or the piping of water jackets filled with rust or sediment
+the speed of water circulation will be slow, which will also be the case
+if the water pump or its driving means fail. Any scale or sediment in
+the water jackets or in the piping or radiator passages will reduce the
+heat conductivity of the metal exposed to the air, and the water will
+not be cooled as quickly as though the scale was not present.
+
+The rubber hose often used in making the flexible connections demanded
+between the radiator and water manifolds of the engine may deteriorate
+inside and particles of rubber hang down that will reduce the area of
+the passage. The grease from the grease cups mounted on the pump-shaft
+bearing to lubricate that member often finds its way into the water
+system and rots the inner walls of the rubber hose, this resulting in
+strips of the partly decomposed rubber lining hanging down and
+restricting the passage. The cooling system is prone to overheat after
+antifreezing solutions of which calcium chloride forms a part have been
+used. This is due to the formation of crystals of salt in the radiator
+passages or water jackets, and these crystals can only be dissolved by
+suitable chemical means, or removed by scraping when the construction
+permits.
+
+Overheating is often caused by some condition in the fuel system that
+produces too rich or too lean mixture. Excess gasoline may be supplied
+if any of the following conditions are present: Bore of spray nozzle or
+standpipe too large, auxiliary air-valve spring too tight, gasoline
+level too high, loose regulating valve, fuel-soaked cork float,
+punctured sheet-metal float, dirt under float control shut-off valve or
+insufficient air supply because of a clogged air screen. If pressure
+feed is utilized there may be too much pressure in the tank, or the
+float controlled mechanism operating the shut-off in the float bowl of
+the carburetor may not act quickly enough.
+
+
+SOME CAUSES OF NOISY OPERATION
+
+There are a number of power-plant derangements which give positive
+indication because of noisy operation. Any knocking or rattling sounds
+are usually produced by wear in connecting rods or main bearings of the
+engine, though sometimes a sharp metallic knock, which is very much the
+same as that produced by a loose bearing, is due to carbon deposits in
+the cylinder heads, or premature ignition due to advanced spark-time
+lever. Squeaking sounds invariably indicate dry bearings, and whenever
+such a sound is heard it should be immediately located and oil applied
+to the parts thus denoting their dry condition. Whistling or blowing
+sounds are produced by leaks, either in the engine itself or in the gas
+manifolds. A sharp whistle denotes the escape of gas under pressure and
+is usually caused by a defective packing or gasket that seals a portion
+of the combustion chamber or that is used for a joint as the exhaust
+manifold. A blowing sound indicates a leaky packing in crank-case.
+Grinding noises in the motor are usually caused by the timing gears and
+will obtain if these gears are dry or if they have become worn. Whenever
+a loud knocking sound is heard careful inspection should be made to
+locate the cause of the trouble. Much harm may be done in a few minutes
+if the engine is run with loose connecting rod or bearings that would be
+prevented by taking up the wear or looseness between the parts by some
+means of adjustment.
+
+
+BRIEF SUMMARY OF HINTS FOR STARTING ENGINE
+
+First make sure that all cylinders have compression. To ascertain this,
+open pet cocks of all cylinders except the one to be tested, crank over
+motor and see that a strong opposition to cranking is met with once in
+two revolutions. If motor has no pet cocks, crank and notice that
+oppositions are met at equal distances, two to every revolution of the
+starting crank in a four-cylinder motor. If compression is lacking,
+examine the parts of the cylinder or cylinders at fault in the following
+order, trying to start the motor whenever any one fault is found and
+remedied. See that the valve push rods or rocker arms do not touch valve
+stems for more than approximately 1/2 revolution in every 2 revolutions,
+and that there is not more than .010 to .020 inch clearance between them
+depending on the make of the motor. Make sure that the exhaust valve
+seats. To determine this examine the spring and see that it is connected
+to the valve stem properly. Take out valve and see that there is no
+obstruction, such as carbon, on its seat. See that valve works freely in
+its guide. Examine inlet valve in same manner. Listen for hissing sound
+while cranking motor for leaks at other places.
+
+Make sure that a spark occurs in each cylinder as follows: If magneto or
+magneto and battery with non-vibrating coil is used: Disconnect wire
+from spark-plug, hold end about 1/8 inch from cylinder or terminal of
+spark-plug. Have motor cranked briskly and see if spark occurs. Examine
+adjustment of interrupter points. See that wires are placed correctly
+and not short circuited. Take out spark-plug and lay it on the cylinder,
+being careful that base of plug only touches the cylinder and that
+ignition wire is connected. Have motor cranked briskly and see if spark
+occurs. Check timing of magneto and see that all brushes are making
+contact.
+
+See if there is gasoline in the carburetor. See that there is gasoline
+in the tank. Examine valve at tank. Prime carburetor and see that spray
+nozzle passage is clear. Be sure throttle is open. Prime cylinders by
+putting about a teaspoonful of gasoline in through pet cock or
+spark-plug opening. Adjust carburetor if necessary.
+
+
+LOCATION OF ENGINE TROUBLES MADE EASY
+
+The following tabulation has been prepared and originated by the writer
+to outline in a simple manner the various troubles and derangements that
+interfere with efficient internal-combustion engine action. The parts
+and their functions are practically the same in all gas or gasoline
+engines of the four-cycle type, and the general instructions given apply
+just as well to all hydro-carbon engines, even if the parts differ in
+form materially. The essential components are clearly indicated in the
+many part sectional drawings in this book so they may be easily
+recognized. The various defects that may materialize are tabulated in a
+manner that makes for ready reference, and the various defective
+conditions are found opposite the part affected, and under a heading
+that denotes the main trouble to which the others are contributing
+causes. The various symptoms denoting the individual troubles outlined
+are given to facilitate their recognition in a positive manner.
+
+Brief note is also made of the remedies for the restoration of the
+defective part or condition. It is apparent that a table of this
+character is intended merely as a guide, and it is a compilation of
+practically all the known troubles that may materialize in gas-engine
+operation. While most of the defects outlined are common enough to
+warrant suspicion, they will never exist in an engine all at the same
+time, and it will be necessary to make a systematic search for such of
+those as exist.
+
+To use the list advantageously, it is necessary to know one main trouble
+easily recognized. For example, if the power plant is noisy, look for
+the possible troubles under the head of Noisy Operation; if it lacks
+capacity, the derangement will undoubtedly be found under the head of
+Lost Power. It is assumed in all cases that the trouble exists in the
+power plant or its components, and not in the auxiliary members of the
+ignition, carburetion, lubrication, or cooling systems. The novice and
+student will readily recognize the parts of the average aviation engine
+by referring to the very complete and clearly lettered illustrations of
+mechanism given in many parts of this treatise.
+
+
+LOST POWER AND OVERHEATING
+
+  ------------------+------------------+------------------+--------------------
+   PART AFFECTED    |NATURE OF TROUBLE |   SYMPTOMS AND   |      REMEDY
+                    |                  |     EFFECTS      |
+  ------------------+------------------+------------------+--------------------
+  Water Pipe Joint. |Loose.            |Loss of water,    |Tighten bolts,
+                    |                  |heating.          |replace gaskets.
+                    |                  |                  |
+  Spark Plug.       |Leakage in        |Loss of power.    |Replace insulation
+                    |threads,          |Hissing caused by |if defective, screw
+                    |insulation,       |escaping gas.     |down tighter.
+                    |packing.          |                  |
+                    |                  |                  |
+  Compression       |Leak in threads.  |Loss of power.    |Tighten if loose.
+  Release Cock.     |Leak in fitting.  |Whistling or      |Grind fitting to
+                    |                  |hissing.          |new seating in
+                    |                  |                  |body.
+                    |                  |                  |
+  Combustion        |Crack or blowhole.|Loss of compres-  |Fill by welding.
+  Chamber.          |Roughness. Carbon |sion. Preignition.|Smooth out
+                    |deposits. Sharp   |                  |roughness. Scrape
+                    |edges.            |                  |out or dissolve
+                    |                  |                  |carbon.
+                    |                  |                  |
+  Valve Chamber Cap.|Leak in threads.  |Loss of compres-  |Remove. Apply pipe
+                    |Defective gasket. |sion. Hissing.    |compound to threads
+                    |                  |                  |and replace. Use
+                    |                  |                  |new gasket or
+                    |                  |                  |packing.
+                    |                  |                  |
+  Valve Head.       |Warped. Scored or |Loss of compres-  |True up in lathe.
+                    |pitted. Carbon-   |sion.             |Grind to seat.
+                    |ized. Covered with|                  |Scrape off. Smooth
+                    |scale. Loose on   |                  |with emery cloth.
+                    |stem (two-piece   |                  |Tighten by
+                    |valves only).     |                  |riveting.
+                    |                  |                  |
+  Valve Seat.       |Warped or pitted. |Loss of compres-  |Use reseating
+                    |Covered with car- |sion.             |reamer. Clean off
+                    |bon. Foreign mat- |                  |and grind valve to
+                    |ter between valve |                  |seat.
+                    |and seat.         |                  |
+                    |                  |                  |
+  Valve Stem.       |Covered with      |Valve does not    |Clean with emery
+                    |scale. Bent. Bind-|close. Loss of    |cloth; straighten.
+                    |ing in guide.     |compression.      |True up and smooth
+                    |Stuck in guide.   |                  |off. free with
+                    |                  |                  |kerosene.
+                    |                  |                  |
+  Valve Stem Guide. |Burnt or rough.   |Valve may stick.  |Clean out hole.
+                    |Loose in valve    |Action irregular. |Screw in tighter.
+                    |chamber.          |                  |
+                    |                  |                  |
+  Valve Spring.     |Weak or broken.   |Valve does not    |
+                    |                  |close.            |
+                    |                  |                  |
+  Valve Operating   |Loose in guide.   |Valve action poor.|Replace with new.
+  Plunger.          |Too much clearance|Lift insufficient.|Adjust screw closer.
+                    |between valve     |                  |
+                    |stem.             |                  |
+                    |                  |                  |
+  Valve Lift Ad-    |Threads stripped. |Poor valve action.|Replace with new.
+  justing Screw.    |Too near valve.   |                  |Adjust with proper
+                    |Too far from      |                  |reference to valve
+                    |valve.            |                  |stem.
+                    |                  |                  |
+  Valve Lift Cam.   |Worn cam contour. |Not enough valve  |Replace with new.
+                    |Loose on shaft.   |lift. Will not    |Replace pins or
+                    |Out of time.      |lift valve. Valve |keys. Set to open
+                    |                  |opens at wrong    |properly.
+                    |                  |time.             |
+                    |                  |                  |
+  Cam-shaft.        |Sprung or twisted.|Valves out of     |Straighten.
+                    |                  |time.             |
+                    |                  |                  |
+  Cam-shaft Bushing.|Worn.             |Not enough valve  |Replace.
+                    |                  |lift.             |
+                    |                  |                  |
+  Cam-shaft Drive   |Loose on shaft.   |Irregular valve   |Fasten securely.
+  Gear.             |Out of time. Worn |action.           |Time properly.
+                    |or broken teeth.  |                  |Replace with new.
+                    |                  |                  |
+  Cam Fastenings.   |Worn or broken.   |Valves out of     |Replace with new.
+                    |                  |time.             |
+                    |                  |                  |
+  Cylinder Wall.    |Scored, gas leaks.|Poor compression. |Grind out bore.
+                    |Poor lubrication  |Overheating.      |Repair oiling
+                    |causes friction.  |                  |system.
+                    |                  |                  |
+  Piston.           |Binds in cylinder.|Overheating. Poor |Lap off excess
+                    |Walls scored. Worn|compression.      |metal. Replace with
+                    |out of round.     |                  |new.
+                    |                  |                  |
+  Piston Rings.     |Loss of spring.   |Loss of compres-  |Peen ring or
+                    |Loose in grooves. |sion. Gas blows   |replace. Fit new
+                    |Scored. Worn or   |by.               |rings. Grind smooth.
+                    |broken. Slots in  |                  |Replace. Turn slots
+                    |line.             |                  |apart.
+                    |                  |                  |
+                    |Carbon in grooves.|Overheating be-   |Remove deposits.
+                    |Insufficient open-|cause of friction.|File slot. Grind or
+                    |ing. Binding on   |                  |lap to fit cylinder
+                    |cylinder.         |                  |bore.
+                    |                  |                  |
+  Wristpin.         |Loose, scores     |Loss of compres-  |Fasten securely.
+                    |cylinder.         |sion.             |Replace cylinder if
+                    |                  |                  |groove is deep.
+                    |                  |                  |
+  Crank-shaft.      |Scored or rough on|Overheating be-   |Smooth up.
+                    |journals. Sprung. |cause of friction.|Straighten.
+                    |                  |                  |
+  Crank Bearings.   |Adjusted too      |Overheating be-   |Adjust freely, clean
+  Main Bearings.    |tight. Defective  |cause of friction.|out oil holes and
+                    |oiling. Brasses   |                  |enlarge oil grooves.
+                    |burned.           |                  |
+                    |                  |                  |
+  Oil Sump.         |Insufficient oil. |Overheating.      |Replenish supply.
+                    |Poor lubricant.   |                  |Use best oil. Wash
+                    |Dirty oil.        |                  |out with kerosene;
+                    |                  |                  |put in clean oil.
+                    |                  |                  |
+  Water Space. Water|Clogged with sedi-|Overheating.      |Dissolve foreign
+  Pipes.            |ment or scale.    |                  |matter and remove.
+                    |                  |                  |
+  Piston Head.      |Cracked (rare).   |Loss of compres-  |Weld by autogenous
+                    |Carbon deposits.  |sion. Preignition.|process. Scrape off
+                    |                  |                  |carbon accumula-
+                    |                  |                  |tions.
+  ------------------+------------------+------------------+--------------------
+
+
+NOISY OPERATION OF POWER PLANT
+
+  ------------------+------------------+------------------+--------------------
+   PART AFFECTED    |NATURE OF TROUBLE |   CHARACTER OF   |      REMEDY
+                    |                  |      NOISE       |
+  ------------------+------------------+------------------+--------------------
+  Compression Re-   |Leakage.          |Hissing.          |Previously given.
+  lease Cock.       |                  |                  |
+                    |                  |                  |
+  Spark Plug.       |Leakage.          |Hissing.          |Previously given.
+                    |                  |                  |
+  Valve Chamber Cap.|Leakage.          |Hiss or whistle.  |Previously given.
+                    |                  |                  |
+  Combustion        |Carbon deposits.  |Knocking.         |Previously given.
+  Chamber.          |                  |                  |
+                    |                  |                  |
+  Inlet Valve Seat. |Defects previously|Popping in carbu- |Previously given.
+                    |given.            |retor.            |
+                    |                  |                  |
+  Valve Head.       |Loose on stem.    |Clicking.         |Previously given.
+                    |                  |                  |
+  Valve Stem. Valve |Wear or looseness.|Rattle or click-  |Previously given.
+  Stem Guide.       |                  |ing.              |
+                    |                  |                  |
+  Inlet Valve.      |Closes too late.  |Blowback in carbu-|Previously given.
+                    |Opens too early.  |retor.            |
+                    |                  |                  |
+  Valve Spring.     |Weak or broken.   |Blowback in carbu-|Previously given.
+                    |                  |retor.            |
+                    |                  |                  |
+  Cylinder Casting. |Retaining bolts   |Sharp metallic    |Tighten bolts. Round
+                    |loose. Piston     |knock.            |edges of  piston
+                    |strikes at upper  |                  |top.
+                    |end.              |                  |
+                    |                  |                  |
+  Cylinder Wall.    |Scored.           |Hissing.          |Previously given.
+                    |                  |                  |
+  Valve Stem        |Too much.         |Clicking. Blowback|Previously given.
+  Clearance.        |Too little (inlet |in carburetor.    |
+                    |valve).           |                  |
+                    |                  |                  |
+  Valve Operating   |Looseness.        |Rattle or click-  |Previously given.
+  Plunger. Plunger  |                  |ing.              |
+  Guide.            |                  |                  |
+                    |                  |                  |
+  Timing Gears.     |Loose on fasten-  |Metallic knock.   |Previously given.
+                    |ings. Worn teeth. |Rattle. Grinding. |
+                    |                  |                  |
+  Cylinder or       |No oil, or poor   |Grinding.         |Repair oil system.
+  Piston.           |lubricant.        |                  |
+                    |                  |                  |
+  Cam.              |Loose on shaft.   |Metallic knock.   |Previously given.
+                    |Worn contour.     |                  |
+                    |                  |                  |
+  Cam-shaft Bearing.|Looseness or wear.|Slight knock.     |Previously given.
+                    |                  |                  |
+  Cam Fastening.    |Looseness.        |Clicking.         |Previously given.
+                    |                  |                  |
+  Piston.           |Binding in cylin- |Grinding or dull  |Previously given.
+                    |der. Worn oval,   |squeak. Dull      |
+                    |causes side slap  |hammering.        |
+                    |in cylinder.      |                  |
+                    |                  |                  |
+  Piston Head.      |Carbon deposits.  |Knocking.         |Previously given.
+                    |                  |                  |
+  Piston Rings.     |Defective oiling. |Squeaking. Hiss-  |Previously given.
+                    |Leakage. Binding  |ing. Grinding.    |
+                    |in cylinder.      |                  |
+                    |                  |                  |
+  Wrist-pin.        |Loose in piston.  |Dull metallic     |Replace with new
+                    |Worn.             |knock.            |member.
+                    |                  |                  |
+  Connecting Rod.   |Wear in upper     |Distinct knock.   |Adjust or replace.
+                    |bushing. Wear at  |                  |Scrape and fit. Use
+                    |crank-pin. Side   |                  |longer wrist-pin
+                    |play in piston.   |                  |bushing.
+                    |                  |                  |
+  Crank Bearings.   |Looseness. Exces- |Metallic knock.   |Refit bearings.
+                    |sive end play.    |Intermittent      |Longer bushings
+                    |Binding, fitted   |knock. Squeaking. |needed. Insert shims
+                    |too tight.        |                  |to allow more play.
+                    |                  |                  |
+  Main Bearings.    |Looseness. Defec- |Metallic knock.   |Fit brasses closer
+                    |tive lubrication. |Squeaking.        |to shaft. Clean out
+                    |                  |                  |oil holes and
+                    |                  |                  |grooves.
+                    |                  |                  |
+  Connecting Rod    |Loose.            |Sharp knock.      |Tighten.
+  Bolts. Main       |                  |                  |
+  Bearing Bolts.    |                  |                  |
+                    |                  |                  |
+  Crank-shaft.      |Defective oiling. |Squeaking.        |Previously given.
+                    |                  |                  |
+  Engine Base.      |Loose on frame.   |Sharp pounding.   |Tighten bolts.
+                    |                  |                  |
+  Lower Half Crank- |Bolts loose.      |Knocking.         |Tighten bolts.
+  case.             |                  |                  |
+                    |                  |                  |
+  Fly-wheel.        |Loose on crank-   |Very sharp knock. |Tighten retention
+                    |shaft.            |                  |bolts or fit new
+                    |                  |                  |keys.
+                    |                  |                  |
+  Oil Sump.         |Oil level too low.|Grinding and      |Replenish with best
+                    |Poor lubricant.   |squeak in all     |cylinder oil.
+                    |                  |bearings.         |
+                    |                  |                  |
+  Valve Plunger Re- |Looseness.        |Clicking.         |Tighten nuts.
+  tention Stirrups. |                  |                  |
+                    |                  |                  |
+  Fan.              |Blade loose. Blade|Clicking or       |Tighten. Bend back.
+                    |strikes cooler.   |rattle.           |
+                    |                  |                  |
+  Exhaust Pipe      |Leakage.          |Sharp hissing.    |Tighten or use new
+  Joints.           |                  |                  |gasket.
+                    |                  |                  |
+  Crank-case        |Leakage.          |Blowing sound.    |Use new packing.
+  Packing.          |                  |                  |Tighten bolts.
+                    |                  |                  |
+  Water Pipe.       |Leaks. Loss of    |Pounding because  |Previously given.
+                    |water. Clogged    |engine heats.     |
+                    |with sediment.    |                  |
+                    |                  |                  |
+  Water Jacket.     |Clogged with sedi-|Knocking because  |Dissolve scale and
+                    |ment. Walls       |engine heats.     |flush out water
+                    |covered with      |                  |space with water
+                    |scale.            |                  |under pressure.
+--------------------+------------------+------------------+--------------------
+
+
+"SKIPPING" OR IRREGULAR OPERATION
+
+  ------------------+------------------+------------------+--------------------
+   PART AFFECTED    |NATURE OF TROUBLE |   SYMPTOMS AND   |      REMEDY
+                    |                  |     EFFECTS      |
+  ------------------+------------------+------------------+--------------------
+  Compression Relief|Leak in threads or|Dilutes mixture   |Screw down tighter.
+  Cock.             |spigot.           |with air, causes  |Grind spigot to seat
+                    |                  |blowback.         |with emery.
+                    |                  |                  |
+  Spark-Plug.       |Leak in threads.  |Dilutes mixture.  |Screw down tighter.
+                    |Defective gasket. |Allows short      |Replace with new.
+                    |Cracked insulator.|circuit. No spark.|Set points 1/64"
+                    |Points too near.  |                  |apart for magneto,
+                    |Points covered    |                  |1/32" for battery
+                    |with carbon. Too  |                  |spark.
+                    |much air gap.     |                  |
+                    |                  |                  |
+  Valve Chamber Cap.|Leak in threads.  |Dilutes mixture by|Previously given.
+                    |Defective gasket. |allowing air to   |
+                    |                  |enter cylinder on |
+                    |                  |suction stroke.   |
+                    |                  |                  |
+  Combustion        |Carbon deposits.  |Preignition.      |Scrape out.
+  Chamber.          |                  |                  |
+                    |                  |                  |
+  Valve Head.       |Warped or pitted. |Dilutes charge    |Previously given.
+                    |Loose on stem.    |with poor air or  |
+                    |                  |gas.              |
+                    |                  |                  |
+  Valve Stem.       |Binding in guide. |Irregular valve   |Previously given.
+                    |Sticking.         |action.           |
+                    |                  |                  |
+  Valve Seat.       |Scored or warped. |Gas leak, poor    |Previously given.
+                    |Cracked. Covered  |mixture. Poor com-|
+                    |with scale. Dirt  |pression. Valve   |
+                    |under valve.      |will not close.   |
+                    |                  |                  |
+  Induction Pipe.   |Leak at joints.   |Mixture diluted   |Stop all leaks.
+                    |Crack or blowhole.|with excess air.  |
+                    |                  |                  |
+  Inlet Valve.      |Closes too late.  |Blowback in carbu-|Time properly.
+                    |Opens too early.  |retor.            |
+                    |                  |                  |
+  Exhaust Valve.    |Opens too late.   |Retention of burnt|Time properly.
+                    |Closes too early. |gas dilutes       |
+                    |                  |charge.           |
+                    |                  |                  |
+  Valve Stem Guide. |Bent or carbon-   |Causes valve to   |Previously given.
+                    |ized.             |stick.            |
+                    |                  |                  |
+  Inlet Valve Stem  |Worn, stem loose. |Air drawn in on   |Bush guide or use
+  Guide.            |                  |suction thins gas.|new member.
+                    |                  |                  |
+  Valve Spring.     |Weakened or       |Irregular action. |Use new spring.
+                    |broken.           |                  |
+                    |                  |                  |
+  Valve Stem        |Too little. Too   |Valve will not    |Adjust gap .009"
+  Clearance.        |much.             |shut. Valve opens |inlet, .010"
+                    |                  |late, closes      |exhaust.
+                    |                  |early.            |
+  Valve Spring      |Broken.           |Releases spring.  |Replace.
+  Collar Key.       |                  |                  |
+                    |                  |                  |
+  Cam.              |Worn cam contour. |Valve lift re-    |Previously given.
+                    |Loose on shaft.   |duced. Does not   |
+                    |Out of time.      |lift valve. Valves|
+                    |                  |operate at wrong  |
+                    |                  |time.             |
+                    |                  |                  |
+  Cam-shaft Bearing.|Looseness or wear.|Valve timing      |Replace.
+                    |                  |altered. Valve    |
+                    |                  |lift decreased.   |
+                    |                  |                  |
+  Cam-shaft.        |Twisted.          |Valves out of     |Previously given.
+                    |                  |time.             |
+                    |                  |                  |
+  Cam Fastening.    |Worn or broken.   |Valve action      |Replace with new.
+                    |                  |irregular.        |
+                    |                  |                  |
+  Valve Operating   |Loose in guide.   |Alters valve      |Replace with new.
+  Plunger.          |                  |timing.           |
+                    |                  |                  |
+  Valve Plunger     |Wear in bore.     |Alters valve      |Replace or bush.
+  Guide.            |Loose on engine   |timing.           |Fasten securely.
+                    |base.             |                  |
+                    |                  |                  |
+  Timing Gears.     |Not properly      |Valves out of     |Retime properly.
+                    |meshed. Loose on  |time. Valves do   |Fasten to shaft.
+                    |shaft.            |not operate.      |
+                    |                  |                  |
+  Piston.           |Walls scored.     |Leakage of gas.   |Smooth up if
+                    |                  |                  |possible.
+                    |                  |                  |
+  Piston Head.      |Carbon deposits.  |Cause premature   |Previously given.
+                    |Crack or blowhole |ignition.         |
+                    |(rare).           |                  |
+                    |                  |                  |
+  Piston Rings.     |No spring. Loose  |Leakage weakens   |Previously given.
+                    |in grooves. Worn  |suction.          |
+                    |or broken.        |                  |
+                    |                  |                  |
+  Cylinder Wall.    |Scored by wrist-  |Gas leaks by. Poor|Previously given.
+                    |pin. Scored by    |suction.          |
+                    |lack of oil.      |                  |
+  ------------------+------------------+------------------+--------------------
+
+
+IGNITION SYSTEM TROUBLES ONLY
+
+
+_Motor Will Not Start or Starts Hard_
+
+  Loose Battery Terminal.
+  Magneto Ground Wire Shorted.
+  Magneto Defective (No Spark at Plugs).
+  Broken Spark Plug Insulation.
+  Carbon Deposits or Oil Between Plug Points.
+  Spark-Plug Points Too Near Together or Far Apart.
+  Wrong Cables to Plugs.
+  Short Circuited Secondary Cable.
+  Broken Secondary Cable.
+  Dry Battery Weak.            }
+  Storage Battery Discharged.  } Battery Systems
+  Poor Contact at Timer.       } Only.
+  Timer Points Dirty.          }
+  Poor Contact at Switch.                    }
+  Primary Wires Broken, or Short Circuited.  } Battery and
+  Battery Grounded in Metal Container.       } Coil Ignition
+  Battery Connectors Broken or Loose.        } System Only.
+  Timer Points Out of Adjustment.            }
+  Defects in Induction Coil.                 }
+  Ignition Timing Wrong, Spark Too Late or Too Early.
+  Defective Platinum Points in Breaker Box (Magneto).
+  Points Not Separating.
+  Broken Contact Maker Spring.
+  No Contact at Secondary Collector Brush.
+  Platinum Contact Points Burnt or Pitted.
+  Contact Breaker Bell Crank Stuck.
+  Fiber Bushing in Bell Crank Swollen.
+  Short Circuiting Spring Always in Contact.
+  Dirt or Water in Magneto Casing.
+  Oil in Contact Breaker.
+  Oil Soaked Brush and Collector Ring.
+  Distributor Filled with Carbon Particles.
+
+
+_Motor Stops Without Warning_
+
+  Broken Magneto Carbon Brush.
+  Broken Lead Wire.
+  Broken Ground Wire.
+  Battery Ignition Systems.
+  Water on High Tension Magneto Terminal.
+  Main Secondary Cable Burnt Through by Hot Exhaust
+  Pipe (Transformer Coil, Magneto Systems).
+  Particle of Carbon Between Spark Plug Points.
+  Magneto Short Circuited by Ground Wire.
+  Magneto Out of Time, Due to Slipping Drive.
+  Water or Oil in Safety Spark Gap (Multi-cylinder Magneto).
+  Magneto Contact Breaker or Timer Stuck in Retard
+  Position.
+  Worn Fiber Block in Magneto Contact Breaker.
+  Binding Fiber Bushing in Contact Breaker Bell Crank.
+  Spark Advance Rod or Wire Broken.
+  Contact Breaker Parts Stuck.
+
+
+_Motor Runs Irregularly or Misfires_
+
+  Loose Wiring or Terminals.
+  Broken Spark-Plug Insulator.
+  Spark-Plug Points Sooted or Oily.
+  Wrong Spark Gap at Plug Points.
+  Leaking Secondary Cable.
+  Prematurely Grounded Primary Wire.
+  Batteries Running Down (Battery Ignition only).
+  Poor Adjustment of Contact Points at Timer.
+  Wire Broken Inside of Insulation.
+  Loose Platinum Points in Magneto.
+  Weak Contact Spring.
+  Broken Collector Brush.
+  Dirt in Magneto Distributor Casing or Contact Breaker.
+  Worn Fiber Block or Cam Plate in Magneto.
+  Worn Cam or Contact Roll in Timer (Battery System
+  only).
+  Dirty Oil in Timer.
+  Sticking Coil Vibrators.
+  Coil Vibrator Points Pitted.
+  Oil Soaked Magneto Winding.
+  Punctured Magneto or Coil Winding.
+  Distributor Contact Segments Rough.
+  Sulphated Storage Battery Terminals.
+  Weak Magnets in Magneto.
+  Poor Contact at Magneto Contact Breaker Points.
+
+
+DEFECTS IN ELECTRICAL SYSTEM COMPONENTS
+
+To further simplify the location of electrical system faults it is
+thought desirable to outline the defects that can be present in the
+various parts of the individual devices comprising the ignition system.
+If an airplane engine is provided with magneto ignition solely, as most
+engines are at the present time, no attention need be paid to such items
+as storage or dry batteries, timer or induction coil. There seems to be
+some development in the direction of battery ignition so it has been
+considered desirable to include components of these systems as well as
+the almost universally used magneto group. Spark-plugs, wiring and
+switches are needed with either system.
+
+
+SPARK-PLUGS
+
+  DEFECT                       TROUBLE CAUSED          REMEDY
+  Insulation cracked.          Plug inoperative.       New insulation.
+  Insulation oil soaked.       Cylinder misfires.      Clean.
+  Carbon deposits.             Short circuited spark.  Remove.
+  Insulator loose.             Cylinder misfires.      Tighten.
+  Gasket broken.               Gas leaks by.           New gasket.
+  Electrode loose on shell.    Cylinder misfires.      Tighten.
+  Wire loose in insulator.     Cylinder misfires.      Tighten.
+  Air gap too close.           Short circuits spark.   Set correctly.
+  Air gap too wide.            Spark will not jump.    Set points 1/32"
+                                                       apart.
+  Loose terminal.              Cylinder may misfire.   Tighten.
+  Plug loose in cylinder.      Gas leaks.              Tighten.
+  Mica insulation oil soaked.  Short circuits spark.   Replace.
+
+
+MAGNETO
+
+  DEFECT                       TROUBLE CAUSED          REMEDY
+  Dirty oil in distributor.    Engine misfires.        Clean.
+  Metal dust in distributor.   Engine misfires.        Clean.
+  Brushes not making contact.  Current cannot pass.    Strengthen
+                                                       spring.
+  Distributor segments worn.   Engine misfires.        Secure even
+                                                       bearing.
+  Collecting brush broken.     Engine misfires.        New brush.
+  Distributing brush broken.   Engine misfires.        New brush.
+  Oil soaked winding.          Engine misfires.        Clean.
+  Magnets loose on pole        Engine misfires.        Tighten screws.
+  pieces.
+  Armature rubs.               Engine misfires.        Repair bearings.
+  Bearings worn.               Noisy.                  Replace.
+  Magnets weak.                Weak spark.             Recharge.
+  Contact breaker points       Engine misfires.        Clean.
+  pitted.
+  Breaker points out of        Engine misfires.        Reset.
+  adjustment.
+  Defective winding (rare).    No spark.               Replace.
+  Punctured condenser (rare).  Weak or no spark.       Replace.
+  Driving gear loose.          Noise.                  Tighten.
+  Magneto armature out of      Spark will not fire     Retime.
+  time.                        charge.
+  Magneto loose on base.       Misfiring and noisy.    Tighten.
+  Contact breaker cam worn.    Misfiring.              Replace.
+  Fibre shoe or rolls worn     Misfiring.              Replace.
+  (Bosch).
+  Fibre bushing binding in     Misfiring.              Ream slightly.
+  contact lever (Bosch).
+  Contact lever return spring  No spark.               Replace.
+  broken.
+  Contact lever return spring  Misfiring.              Replace.
+  weak.
+  Ground wire grounded.        No spark.               Insulate.
+  Ground wire broken.          Engine will not stop.   Connect up.
+  Safety spark gap dirty.      No spark.               Clean.
+  Fused metal in spark gap.    No spark.               Remove.
+  Safety spark gap points too  Misfiring.              Set properly.
+  close.
+  Loose distributor terminals. Misfiring.              Tighten.
+  Contact breaker sticks.      No spark control.       Remove and clean
+                                                       bearings.
+  Magneto switch short-        No spark.               Insulate.
+  circuited.
+  Magneto switch open circuit. No engine stop.         Restore contact.
+
+
+STORAGE BATTERY
+
+  DEFECT                       TROUBLE CAUSED          REMEDY
+  Electrolyte low.             Weak current.           Replenish with
+                                                       distilled water.
+  Loose terminals.             Misfiring.              Tighten.
+  Sulphated terminals.         Misfiring.              Clean thoroughly
+                                                       and coat with
+                                                       vaseline.
+  Battery discharged.          Misfiring or no spark.  New charge.
+  Electrolyte weak.            Weak current.           Bring to proper
+                                                       specific gravity.
+  Plates sulphated.            Poor capacity.          Special slow charge.
+  Sediment or mud in bottom.   Weak current.           Clean out.
+  Active material loose in     Poor capacity.          New plates.
+  grids.
+  Moisture or acid on top of   Shorts terminals.       Remove.
+  cells.
+  Plugged vent cap.            Buckles cell jars.      Make vent hole.
+  Cracked vent cap.            Acid spills out.        New cap.
+  Cracked cell jar.            Electrolyte runs out.   New jar.
+
+DRY CELL BATTERY
+
+  DEFECT                       TROUBLE CAUSED          REMEDY
+  Broken wires.                No current.             New wires.
+  Loose terminals.             Misfiring.              Tighten.
+  Weak cell (7 amperes or      Misfiring.              New cells.
+  less).
+  Cells in contact.            Short circuit.          Separate and
+                                                       insulate.
+  Water in battery box.        Short circuit.          Dry out.
+
+
+TIMER
+
+  DEFECT                       TROUBLE CAUSED          REMEDY
+  Contact segments worn or     Misfiring.              Grind down
+  pitted.                                              smooth.
+  Platinum points pitted.      Misfiring.              Smooth with oil
+                                                       stone.
+  Dirty oil or metal dust in   Misfiring.              Clean out.
+  interior.
+  Worn bearing.                Misfiring.              Replace.
+  Loose terminals.             Misfiring.              Tighten.
+  Worn revolving contact       Misfiring.              Replace.
+  brush.
+  Out of time.                 Irregular spark.        Reset.
+
+
+INDUCTION COIL
+
+  DEFECT                       TROUBLE CAUSED          REMEDY
+  Loose terminals.             Misfiring.              Tighten.
+  Broken connections.          No spark.               Make new joints.
+  Vibrators out of adjustment. Misfiring.              Readjust.
+  Vibrator points pitted.      Misfiring.              Clean.
+  Defective condenser } rare.  No spark.               Send to maker
+  Defective winding   }                                for repairs.
+  Poor contact at switch.      Misfiring.              Tighten.
+  Broken internal wiring.      No spark.               Replace.
+  Poor coil unit.              One cylinder affected.  Replace.
+
+
+WIRING
+
+  DEFECT                       TROUBLE CAUSED          REMEDY
+  Loose terminals anywhere.    Misfiring.              Tighten.
+  Broken plug wire.            One cylinder will not   Replace.
+                               fire.
+  Broken timer wire.           One coil will not buzz. Replace.
+  Broken main battery wire.  } No spark.               Replace.
+  Broken battery ground wire.}
+  Broken magneto ground wire.  Engine will not stop.   Replace.
+  Chafed insulation anywhere.} Misfiring.              Insulate.
+  Short circuit anywhere.    }
+
+
+CARBURETION SYSTEM FAULTS SUMMARIZED
+
+
+_Motor Starts Hard or Will Not Start_
+
+  No Gasoline in Tank.
+  No Gasoline in Carburetor Float Chamber.
+  Tank Shut-Off Closed.
+  Clogged Filter Screen.
+  Fuel Supply Pipe Clogged.
+  Gasoline Level Too Low.
+  Gasoline Level Too High (Flooding).
+  Bent or Stuck Float Lever.
+  Loose or Defective Inlet Manifold.
+  Not Enough Gasoline at Jet.
+  Cylinders Flooded with Gas.
+  Fuel Soaked Cork Float (Causes Flooding).
+  Water in Carburetor Spray Nozzle.
+  Dirt in Float Chamber.
+  Gas Mixture Too Lean.
+  Carburetor Frozen (Winter Only).
+
+
+_Motor Stops In Flight_
+
+  Gasoline Shut-Off Valve Jarred Closed.
+  Gasoline Supply Pipe Clogged.
+  No Gasoline in Tank.
+  Spray Nozzle Stopped Up.
+  Water in Spray Nozzle.
+  Particles of Carbon Between Spark-Plug Points.
+  Magneto Short Circuited by Ground in Wire.
+  Air Lock in Gasoline Pipe.
+  Broken Air Line or Leaky Tank (Pressure Feed System Only).
+  Fuel Supply Pipe Partially Clogged.
+  Air Vent in Tank Filler Cap Stopped Up (Gravity and Vacuum Feed
+  System).
+  Float Needle Valve Stuck.
+  Water or Dirt in Spray Nozzle.
+  Mixture Adjusting Needle Jarred Loose (Rotary Motors Only).
+
+
+_Motor Races, Will Not Throttle Down_
+
+  Air Leak in Inlet Piping.
+  Air Leak Through Inlet Valve Guides.
+  Control Rods Broken.
+  Defective Induction Pipe Joints.
+  Leaky Carburetor Flange Packing.
+  Throttle Not Closing.
+  Poor Slow Speed Adjustment (Zenith Carburetor).
+
+
+_Motor Misfires_
+
+  Carburetor Float Chamber Getting Dry.
+  Water or Dirt in Gasoline.
+  Poor Gasoline Adjustment (Rotary Motors).
+  Not Enough Gasoline in Float Chamber.
+  Too Much Gasoline, Carburetor Flooding.
+  Incorrect Jet or Choke (Zenith Carburetor).
+  Broken Cylinder Head Packing Between Cylinders.
+
+
+_Noisy Operation_
+
+  Popping or Blowing Back in Carburetor.
+  Incorrectly Timed Inlet Valves.
+  Inlet Valve Not Seating.
+  Defective Inlet Valve Spring.
+  Dirt Under Inlet Valve Seat.
+  Not Enough Gasoline (Open Needle Valve).
+  Muffler or Manifold Explosions.
+  Mixture Not Exploding Regularly.
+  Exhaust Valve Sticking.
+  Dirt Under Exhaust Valve Seat.
+
+
+
+
+CHAPTER XI
+
+    Tools for Adjusting and Erecting--Forms of Wrenches--Use and
+    Care of Files--Split Pin Removal and Installation--Complete
+    Chisel Set--Drilling Machines--Drills, Reamers, Taps and Dies--
+    Measuring Tools--Micrometer Calipers and Their Use--Typical Tool
+    Outfits--Special Hall-Scott Tools--Overhauling Airplane Engines
+    --Taking Engine Down--Defects in Cylinders--Carbon Deposits,
+    Cause and Prevention--Use of Carbon Scrapers--Burning Out Carbon
+    with Oxygen--Repairing Scored Cylinders--Valve Removal and
+    Inspection--Reseating and Truing Valves--Valve Grinding
+    Processes--Depreciation in Valve Operating System--Piston
+    Troubles--Piston Ring Manipulation--Fitting Piston Rings--
+    Wrist-Pin Wear--Inspection and Refitting of Engine Bearings--
+    Scraping Brasses to Fit--Fitting Connecting Rods--Testing for
+    Bearing Parallelism--Cam-Shafts and Timing Gears--Precautions in
+    Reassembling Parts.
+
+
+TOOLS FOR ADJUSTING AND ERECTING
+
+[Illustration: Fig. 163.--Practical Hand Tools Useful in Dismantling and
+Repairing Airplane Engines.]
+
+A very complete outfit of small tools, some of which are furnished as
+part of the tool equipment of various engines are shown in group at Fig.
+163. This group includes all of the tools necessary to complete a very
+practical kit and it is not unusual for the mechanic who is continually
+dismantling and erecting engines to possess even a larger assortment
+than indicated. The small bench vise provided is a useful auxiliary that
+can be clamped to any convenient bench or table or even fuselage
+longeron in an emergency and should have jaws at least three inches wide
+and capable of opening four or five inches. It is especially useful in
+that it will save trips to the bench vises, as it has adequate capacity
+to handle practically any of the small parts that need to be worked on
+when making repairs. A blow torch, tinner's snips and soldering copper
+are very useful in sheet metal work and in making any repairs requiring
+the use of solder. The torch can be used in any operation requiring a
+source of heat. The large box wrench shown under the vise is used for
+removing large special nuts and sometimes has one end of the proper size
+to fit the valve chamber cap. The piston ring removers are easily made
+from thin strips of sheet metal securely brazed or soldered to a light
+wire handle. These are used in sets of three for removing and applying
+piston rings in a manner to be indicated. The uses of the wrenches,
+screw drivers, and pliers shown are known to all and the variety
+outlined should be sufficient for all ordinary work of restoration. The
+wrench equipment is very complete, including a set of open end
+S-wrenches to fit all standard bolts, a spanner wrench, socket or box
+wrenches for bolts that are inaccessible with the ordinary type,
+adjustable end wrenches, a thin monkey wrench of medium size, a bicycle
+wrench for handling small nuts and bolts, a Stillson wrench for pipe and
+a large adjustable monkey wrench for the stubborn fastenings of large
+size.
+
+Four different types of pliers are shown, one being a parallel jaw type
+with size cutting attachment, while the other illustrated near it is a
+combination parallel jaw type adapted for use on round work as well as
+in handling flat stock. The most popular form of pliers is the
+combination pattern shown beneath the socket wrench set. This is made of
+substantial drop forgings having a hinged joint that can be set so that
+a very wide opening at the jaws is possible. These can be used on round
+work and for wire cutting as well as for handling flat work. Round nose
+pliers are very useful also.
+
+A very complete set of files, including square, half round, mill, flat
+bastard, three-cornered and rat tail are also necessary. A hacksaw frame
+and a number of saws, some with fine teeth for tubing and others with
+coarser teeth for bar or solid stock will be found almost indispensable.
+A complete punch and chisel set should be provided, samples of which are
+shown in the group while the complete outfit is outlined in another
+illustration. A number of different forms and sizes of chisels are
+necessary, as one type is not suitable for all classes of work. The
+adjustable end wrenches can be used in many places where a monkey wrench
+cannot be fitted and where it will be difficult to use a wrench having a
+fixed opening. The Stillson pipe wrench is useful in turning studs,
+round rods, and pipes that cannot be turned by any other means. A
+complete shop kit must necessarily include various sizes for Stillson
+and monkey wrenches, as no one size can be expected to handle the wide
+range of work the engine repairman must cope with. Three sizes of each
+form of wrench can be used, one, a 6 inch, is as small as is needed
+while, a 12 inch tool will handle almost any piece of pipe or nut used
+in engine construction.
+
+Three or four sizes of hammers should be provided, according to
+individual requirement, these being small riveting, medium and
+heavyweight machinist's hammers. A very practical tool of this nature
+for the repair shop can be used as a hammer, screw driver or pry iron.
+It is known as the "Spartan" hammer and is a tool steel drop forging in
+one piece having the working surfaces properly hardened and tempered
+while the metal is distributed so as to give a good balance to the head
+and a comfortable grip to the handle. The hammer head provides a
+positive and comfortable T-handle when the tool is used as a screw
+driver or "tommy" bar. Machinist's hammers are provided with three types
+of heads, these being of various weights. The form most commonly used is
+termed the "ball pein" on account of the shape of the portion used for
+riveting. The straight pein is just the same as the cross pein, except
+that in the latter the straight portion is at right angles to the hammer
+handle, while in the former it is parallel to that member.
+
+
+FORMS OF WRENCHES
+
+Wrenches have been made in infinite variety and there are a score or
+more patterns of different types of adjustable socket and off-set
+wrenches. The various wrench types that differ from the more
+conventional monkey wrenches or those of the Stillson pattern are shown
+at Fig. 164. The "perfect handle" is a drop forged open end form
+provided with a wooden handle similar to that used on a monkey wrench in
+order to provide a better grip for the hand. The "Saxon" wrench is a
+double alligator form, so called because the jaws are in the form of a
+V-groove having one side of the V plain, while the other is serrated in
+order to secure a tight grip on round objects. In the form shown, two
+jaws of varying sizes are provided, one for large work, the other to
+handle the smaller rods. One of the novel features in connection with
+this wrench is the provision of a triple die block in the centre of the
+handle which is provided with three most commonly used of the standard
+threads including 5/16-inch-18, 3/8-inch-16, and 1/2-inch-13. This is
+useful in cleaning up burred threads on bolts before they are replaced,
+as burring is unavoidable if it has been necessary to drive them out
+with a hammer. The "Lakeside" wrench has an adjustable pawl engaging
+with one of a series of notches by which the opening may be held in any
+desired position.
+
+[Illustration: Fig. 164.--Wrenches are Offered in Many Forms.]
+
+Ever since the socket wrench was invented it has been a popular form
+because it can be used in many places where the ordinary open end or
+monkey wrench cannot be applied owing to lack of room for the head of
+the wrench. A typical set which has been made to fit in a very small
+space is shown at D. It consists of a handle, which is nickel-plated and
+highly polished, a long extension bar, a universal joint and a number of
+case hardened cold drawn steel sockets to fit all commonly used standard
+nuts and bolt heads. Two screw-driver bits, one small and the other
+large to fit the handle, and a long socket to fit spark-plugs are also
+included in this outfit. The universal joint permits one to remove nuts
+in a position that would be inaccessible to any other form of wrench, as
+it enables the socket to be turned even if the handle is at one side of
+an intervening obstruction.
+
+The "Pick-up" wrench, shown at E, is used for spark-plugs and the upper
+end of the socket is provided with a series of grooves into which a
+suitable blade carried by the handle can be dropped. The handle is
+pivoted to the top of the socket in such a way that the blades may be
+picked up out of the grooves by lifting on the end of the handle and
+dropped in again when the handle is swung around to the proper point to
+get another hold on the socket. The "Miller" wrench shown at F, is a
+combination socket and open end type, made especially for use with
+spark-plugs. Both the open end and the socket are convenient. The
+"Handy" set shown at G, consists of a number of thin stamped wrenches of
+steel held together in a group by a simple clamp fitting, which enables
+either end of any one of the four double wrenches to be brought into
+play according to the size of the nut to be turned. The "Cronk" wrench
+shown at H, is a simple stamping having an alligator opening at one end
+and a stepped opening capable of handling four different sizes of
+standard nuts or bolt heads at the other. Such wrenches are very cheap
+and are worth many times their small cost, especially for fitting nuts
+where there is not sufficient room to admit the more conventional
+pattern. The "Starrett" wrench set, which is shown at I, consists of a
+ratchet handle together with an extension bar and universal joint, a
+spark-plug socket, a drilling attachment which takes standard square
+shank drills from 1/8-inch to 1/2-inch in diameter, a double ended
+screw-driver bit and several adjustments to go with the drilling
+attachment. Twenty-eight assorted cold drawn steel sockets similar in
+design to those shown at D, to fit all standard sizes of square and
+hexagonal headed nuts are also included. The reversible ratchet handle,
+which may be slipped over the extension bar or the universal joint and
+which is also adapted to take the squared end of any one of the sockets
+is exceptionally useful in permitting, as it does, the instant release
+of pressure when it is desired to swing the handle back to get another
+hold on the nut. The socket wrench sets are usually supplied in hard
+wood cases or in leather bags so that they may be kept together and
+protected against loss or damage. With a properly selected socket wrench
+set, either of the ratchet handle or T-handle form, any nut on the
+engine may be reached and end wrenches will not be necessary.
+
+
+USE AND CARE OF FILES
+
+Mention has been previously made of the importance of providing a
+complete set of files and suitable handles. These should be in various
+grades or degrees of fineness and three of each kind should be provided.
+In the flat and half round files three grades are necessary, one with
+coarse teeth for roughing, and others with medium and fine teeth for the
+finishing cuts. The round or rat tail file is necessary in filing out
+small holes, the half round for finishing the interior of large ones.
+Half round files are also well adapted for finishing surfaces of
+peculiar contour, such as the inside of bearing boxes, connecting rod
+and main bearing caps, etc. Square files are useful in finishing keyways
+or cleaning out burred splines, while the triangular section or
+three-cornered file is of value in cleaning out burred threads and
+sharp corners. Flat files are used on all plane surfaces.
+
+[Illustration: Fig. 165.--Illustrating Use and Care of Files.]
+
+The file brush shown at Fig. 165, A, consists of a large number of wire
+bristles attached to a substantial wood back having a handle of
+convenient form so that the bristles may be drawn through the
+interstices between the teeth of the file to remove dirt and grease. If
+the teeth are filled with pieces of soft metal, such as solder or
+babbitt, it may be necessary to remove this accumulation with a piece of
+sheet metal as indicated at Fig. 165, B. The method of holding a file
+for working on plain surfaces when it is fitted with the regular form of
+wooden handle is shown at C, while two types of handles enabling the
+mechanic to use the flat file on plain surfaces of such size that the
+handle type indicated at C, could not be used on account of interfering
+with the surface finished are shown at D. The method of using a file
+when surfaces are finished by draw filing is shown at E. This differs
+from the usual method of filing and is only used when surfaces are to be
+polished and very little metal removed.
+
+
+SPLIT PIN REMOVAL AND INSERTION
+
+One of the most widely used of the locking means to prevent nuts or
+bolts from becoming loose is the simple split pin, sometimes called a
+"cotter pin." These can be handled very easily if the special pliers
+shown at Fig. 166, A, are used. They have a curved jaw that permits of
+grasping the pin firmly and inserting it in the hole ready to receive
+it. It is not easy to insert these split pins by other means because the
+ends are usually spread out and it is hard to enter the pin in the hole.
+With the cotter pin pliers the ends may be brought close together and as
+the plier jaws are small the pin may be easily pushed in place. Another
+use of this plier, also indicated, is to bend over the ends of the split
+pin in order to prevent it from falling out. To remove these pins a
+simple curved lever, as shown at Fig. 166, B, is used. This has one end
+tapering to a point and is intended to be inserted in the eye of the
+cotter pin, the purchase offered by the handle permitting of ready
+removal of the pin after the ends have been closed by the cotter pin
+pliers.
+
+
+COMPLETE CHISEL SET
+
+[Illustration: Fig. 166.--Outlining Use of Cotter Pin Pliers, Spring
+Winder, and Showing Practical Outfit of Chisels.]
+
+A complete chisel set suitable for repair shop use is also shown at Fig.
+166. The type at C is known as a "cape" chisel and has a narrow cutting
+point and is intended to chip keyways, remove metal out of corners and
+for all other work where the broad cutting edge chisel, shown at D,
+cannot be used. The form with the wide cutting edge is used in chipping,
+cutting sheet metal, etc. At E, a round nose chisel used in making oil
+ways is outlined, while a similar tool having a pointed cutting edge and
+often used for the same purpose is shown at F. The centre punch depicted
+at G, is very useful for marking parts either for identification or for
+drilling. In addition to the chisels shown, a number of solid punches
+or drifts resembling very much that shown at E, except that the point is
+blunt should be provided to drive out taper pins, bolts, rivets, and
+other fastenings of this nature. These should be provided in the common
+sizes. A complete set of real value would start at 1/8-inch and increase
+by increments of 1/32-inch up to 1/2-inch. A simple spring winder is
+shown at Fig. 166, H, this making it possible for the repairman to wind
+coil springs, either on the lathe or in the vise. It will handle a
+number of different sizes of wire and can be set to space the coils as
+desired.
+
+
+DRILLING MACHINES
+
+[Illustration: Fig. 167.--Forms of Hand Operated Drilling Machines.]
+
+Drilling machines may be of two kinds, hand or power operated. For
+drilling small holes in metal it is necessary to run the drill fast,
+therefore the drill chuck is usually driven by gearing in order to
+produce high drill speed without turning the handle too fast. A small
+hand drill is shown at Fig. 167, A. As will be observed, the chuck
+spindle is driven by a small bevel pinion, which in turn, is operated by
+a large bevel gear turned by a crank. The gear ratio is such that one
+turn of the handle will turn the chuck five or six revolutions. A drill
+of this design is not suited for drills any larger than one-quarter
+inch. For use with drills ranging from one-eighth to three-eighths, or
+even half-inch the hand drill presses shown at C and D are used. These
+have a pad at the upper end by which pressure may be exerted with the
+chest in order to feed the drill into the work, and for this reason they
+are termed "breast drills." The form at C has compound gearing, the
+drill chuck being driven by the usual form of bevel pinion in mesh with
+a larger bevel gear at one end of a countershaft. A small helical spur
+pinion at the other end of this countershaft receives its motion from a
+larger gear turned by the hand crank. This arrangement of gearing
+permits of high spindle speed without the use of large gears, as would
+be necessary if but two were used. The form at D gives two speeds, one
+for use with small drills is obtained by engaging the lower bevel pinion
+with the chuck spindle and driving it by the large ring gear. The slow
+speed is obtained by shifting the clutch so that the top bevel pinion
+drives the drill chuck. As this meshes with a gear but slightly larger
+in diameter, a slow speed of the drill chuck is possible. Breast drills
+are provided with a handle screwed into the side of the frame, these
+are used to steady the drill press. For drilling extremely large holes
+which are beyond the capacity of the usual form of drill press the
+ratchet form shown at B, may be used or the bit brace outlined at E. The
+drills used with either of these have square shanks, whereas those used
+in the drill presses have round shanks. The bit brace is also used
+widely in wood work and the form shown is provided with a ratchet by
+which the bit chuck may be turned through only a portion of a revolution
+in either direction if desired.
+
+
+DRILLS, REAMERS, TAPS AND DIES
+
+In addition to the larger machine tools and the simple hand tools
+previously described, an essential item of equipment of any engine or
+plane repair shop, even in cases where the ordinary machine tools are
+not provided, is a complete outfit of drills, reamers, and threading
+tools. Drills are of two general classes, the flat and the twist drills.
+The flat drill has an angle between cutting edges of about 110 degrees
+and is usually made from special steel commercially known as drill rod.
+
+A flat drill cannot be fed into the work very fast because it removes
+metal by a scraping, rather than a cutting process. The twist drill in
+its simplest form is cylindrical throughout the entire length and has
+spiral flutes which are ground off at the end to form the cutting lip
+and which also serve to carry the metal chips out of the holes. The
+simplest form of twist drill used is shown at Fig. 168, C, and is known
+as a "chuck" drill, because it must be placed in a suitable chuck to
+turn it. A twist drill removes metal by cutting and it is not necessary
+to use a heavy feed as the drill will tend to feed itself into the work.
+
+[Illustration: Fig. 168.--Forms of Drills Used in Hand and Power
+Drilling Machines.]
+
+Larger drills than 3/4-inch are usually made with a tapered shank as
+shown at Fig. 168, B. At the end of the taper a tongue is formed which
+engages with a suitable opening in the collet, as the piece used to
+support the drill is called. The object of this tongue is to relieve
+the tapered portion of the drill from the stress of driving by
+frictional contact alone, as this would not turn the drill positively
+and the resulting slippage would wear the socket, this depreciation
+changing the taper and making it unfit for other drills. The tongue is
+usually proportioned so it is adequate to drive the drill under any
+condition. A small keyway is provided in the collet into which a
+tapering key of flat stock may be driven against the end of the tongue
+to drive the drill from the spindle. A standard taper for drill shanks
+generally accepted by the machine trade is known as the Morse and is a
+taper of five-eighths of an inch to the foot. The Brown and Sharp form
+tapers six-tenths of an inch to the foot. Care must be taken, therefore,
+when purchasing drills and collets, to make sure that the tapers
+coincide, as no attempt should be made to run a Morse taper in a Brown
+and Sharp collet, or vice versa.
+
+Sometimes cylindrical drills have straight flutes, as outlined at Fig.
+168, A. Such drills are used with soft metals and are of value when the
+drill is to pass entirely through the work. The trouble with a drill
+with spiral flutes is that it will tend to draw itself through as the
+cutting lips break through. This catching of the drill may break it or
+move the work from its position. With a straight flute drill the cutting
+action is practically the same as with the flat drill shown at Fig. 168,
+E and F.
+
+If a drill is employed in boring holes through close-grained, tough
+metals, as wrought or malleable iron and steel, the operation will be
+facilitated by lubricating the drill with plenty of lard oil or a
+solution of soda and water. Either of these materials will effectually
+remove the heat caused by the friction of the metal removed against the
+lips of the drill, and the danger of heating the drill to a temperature
+that will soften it by drawing the temper is minimized. In drilling
+large or deep holes it is good practice to apply the lubricating medium
+directly at the drill point. Special drills of the form shown at Fig.
+168, B, having a spiral oil tube running in a suitably formed channel,
+provides communication between the point of the drill and a suitable
+receiving hole on a drilled shank. The oil is supplied by a pump and its
+pressure not only promotes positive circulation and removal of heat, but
+also assists in keeping the hole free of chips. In drilling steel or
+wrought iron, lard oil applied to the point of the drill will facilitate
+the drilling, but this material should never be used with either brass
+or cast iron.
+
+The sizes to be provided depend upon the nature of the work and the
+amount of money that can be invested in drills. It is common practice to
+provide a set of drills, such as shown at Fig. 169, which are carried in
+a suitable metal stand, these being known as number drills on account
+of conforming to the wire gauge standards. Number drills do not usually
+run higher than 5/16 inch in diameter. Beyond this point drills are
+usually sold by the diameter. A set of chuck drills, ranging from 3/8 to
+3/4 inch, advancing by 1/32 inch, and a set of Morse taper shank drills
+ranging from 3/4 to 1-1/4 inches, by increments of 1/16 inch, will be
+all that is needed for the most pretentious repair shop, as it is
+cheaper to bore holes larger than 1-1/4 inches with a boring tool than
+it is to carry a number of large drills in stock that would be used very
+seldom, perhaps not enough to justify their cost.
+
+[Illustration: Fig. 169.--Useful Set of Number Drills, Showing Stand for
+Keeping These in an Orderly Manner.]
+
+In grinding drills, care must be taken to have the lips of the same
+length, so that they will form the same angle with the axis. If one lip
+is longer than the other, as shown in the flat drill at Fig. 168, E, the
+hole will be larger than the drill size, and all the work of cutting
+will come upon the longest lip. The drill ends should be symmetrical, as
+shown at Fig. 168, F.
+
+[Illustration: Fig. 170.--Illustrating Standard Forms of Hand and
+Machine Reamers.]
+
+It is considered very difficult to drill a hole to an exact diameter,
+but for the most work a variation of a few thousandths of an inch is of
+no great moment. Where accuracy is necessary, holes must be reamed out
+to the required size. In reaming, a hole is drilled about 1/32 inch
+smaller than is required, and is enlarged with a cutting tool known as
+the reamer. Reamers are usually of the fluted form shown at Fig. 170, A.
+Tools of this nature are not designed to remove considerable amounts of
+metal, but are intended to augment the diameter of the drill hole by
+only a small fraction of an inch. Reamers are tapered slightly at the
+point in order that they will enter the hole easily, but the greater
+portion of the fluted part is straight, all cutting edges being
+parallel. Hand reamers are made in either the straight or taper forms,
+that at A, Fig. 170, being straight, while B has tapering flutes. They
+are intended to be turned by a wrench similar to that employed in
+turning a tap, as shown at Fig. 172, C. The reamer shown at Fig. 170,
+C, is a hand reamer. The form at D has spiral flutes similar to a twist
+drill, and as it is provided with a taper shank it is intended to be
+turned by power through the medium of a suitable collet.
+
+As the solid reamers must become reduced in size when sharpened, various
+forms of inserted blade reamers have been designed. One of these is
+shown at E, and as the cutting surfaces become reduced in diameter it is
+possible to replace the worn blades with others of proper size.
+Expanding reamers are of the form shown at F. These have a bolt passing
+through that fits into a tapering hole in the interior of the split
+reamer portion of the tool. If the hole is to be enlarged a few
+thousandths of an inch, it is possible to draw up on the nut just above
+the squared end of the shank, and by drawing the tapering wedge farther
+into the reamer body, the cutting portion will be expanded and will cut
+a larger hole.
+
+Reamers must be very carefully sharpened or there will be a tendency
+toward chattering with a consequent production of a rough surface. There
+are several methods of preventing this chattering, one being to separate
+the cutting edges by irregular spaces, while the most common method, and
+that to be preferred on machine reamers, is to use spiral flutes, as
+shown at Fig. 170, D. Special taper reamers are made to conform to the
+various taper pin sizes which are sometimes used in holding parts
+together in an engine. A taper of 1/16 inch per foot is intended for
+holes where a pin, once driven in, is to remain in place. When it is
+desired that the pin be driven out, the taper is made steeper, generally
+1/4 inch per foot, which is the standard taper used on taper pins.
+
+[Illustration: Fig. 171.--Tools for Thread Cutting.]
+
+When threads are to be cut in a small hole, it will be apparent that it
+will be difficult to perform this operation economically on a lathe,
+therefore when internal threading is called for, a simple device known
+as a "tap" is used. There are many styles of taps, all conforming to
+different standards. Some are for metric or foreign threads, some
+conform to the American standards, while others are used for pipe and
+tubing. Hand taps are the form most used in repair shops, these being
+outlined at Fig. 171, A and B. They are usually sold in sets of three,
+known respectively as taper, plug, and bottoming. The taper tap is the
+one first put into the hole, and is then followed by the plug tap which
+cuts the threads deeper. If it is imperative that the thread should be
+full size clear to the bottom of the hole, the third tap of the set,
+which is straight-sided, is used. It would be difficult to start a
+bottoming tap into a hole because it would be larger in diameter at its
+point than the hole. The taper tap, as shown at A, Fig. 171, has a
+portion of the cutting lands ground away at the point in order that it
+will enter the hole. The manipulation of a tap is not hard, as it does
+not need to be forced into the work, as the thread will draw it into
+the hole as the tap is turned. The tapering of a tap is done so that no
+one thread is called upon to remove all of the metal, as for about half
+way up the length of the tap each succeeding thread is cut a little
+larger by the cutting edge until the full thread enters the hole. Care
+must be taken to always enter a tap straight in order to have the thread
+at correct angles to the surface.
+
+In cutting external threads on small rods or on small pieces, such as
+bolts and studs, it is not always economical to do this work in the
+lathe, especially in repair work. Dies are used to cut threads on pieces
+that are to be placed in tapped holes that have been threaded by the
+corresponding size of tap. Dies for small work are often made solid, as
+shown at Fig. 171, C, but solid dies are usually limited to sizes below
+1/2 inch. Sometimes the solid die is cylindrical in shape, with a slot
+through one side which enables one to obtain a slight degree of
+adjustment by squeezing the slotted portion together. Large dies, or the
+sizes over 1/2 inch, are usually made in two pieces in order that the
+halves may be closed up or brought nearer together. The advantage of
+this form of die is that either of the two pieces may be easily
+sharpened, and as it may be adjusted very easily the thread may be cut
+by easy stages. For example, the die may be adjusted to cut large, which
+will produce a shallow thread that will act as an accurate guide when
+the die is closed up and a deeper thread cut.
+
+[Illustration: Fig. 172.--Showing Holder Designs for One- and Two-Piece
+Thread Cutting Dies.]
+
+A common form of die holder for an adjustable die is shown at Fig. 172,
+A. As will be apparent, it consists of a central body portion having
+guide members to keep the die pieces from falling out and levers at each
+end in order to permit the operator to exert sufficient force to remove
+the metal. The method of adjusting the depth of thread with a clamp
+screw when a two-piece die is employed is also clearly outlined. The
+diestock shown at B is used for the smaller dies of the one-piece
+pattern, having a slot in order that they may be closed up slightly by
+the clamp screw. The reverse side of the diestock shown at B is outlined
+below it, and the guide pieces, which may be easily moved in or out,
+according to the size of the piece to be threaded by means of
+eccentrically disposed semi-circular slots in the adjustment plate, are
+shown. These movable guide members have small pins let into their
+surface which engage the slots, and they may be moved in or out, as
+desired, according to the position of the adjusting plate. The use of
+the guide pieces makes for accurate positioning or centering of the rod
+to be threaded. Dies are usually sold in sets, and are commonly
+furnished as a portion of a complete outfit such as outlined at Fig.
+173. That shown has two sizes of diestock, a tap wrench, eight assorted
+dies, eight assorted taps, and a small screw driver for adjusting the
+die. An automobile repair shop should be provided with three different
+sets of taps and dies, as three different standards for the bolts and
+nuts are used in fastening automobile components. These are the
+American, metric (used on foreign engines), and the S. A. E. standard
+threads. A set of pipe dies and taps will also be found useful.
+
+[Illustration: Fig. 173.--Useful Outfit of Taps and Dies for the Engine
+Repair Shop.]
+
+
+MEASURING TOOLS
+
+The tool outfit of the machinist or the mechanic who aspires to do
+machine work must include a number of measuring tools which are not
+needed by the floor man or one who merely assembles and takes apart the
+finished pieces. The machinist who must convert raw material into
+finished products requires a number of measuring tools, some of which
+are used for taking only approximate measurements, such as calipers and
+scales, while others are intended to take very accurate measurements,
+such as the Vernier and the micrometer. A number of common forms of
+calipers are shown at Fig. 174. These are known as inside or outside
+calipers, depending upon the measurements they are intended to take.
+That at A is an inside caliper, consisting of two legs, A and D, and a
+gauging piece, B, which can be locked to leg A, or released from that
+member by the screw, C. The object of this construction is to permit of
+measurements being taken at the bottom of a two diameter hole, where the
+point to be measured is of larger diameter than the portion of the hole
+through which the calipers entered. It will be apparent that the legs A
+and D must be brought close together to pass through the smaller holes.
+This may be done without losing the setting, as the guide bar B will
+remain in one position as determined by the size of the hole to be
+measured, while the leg A may be swung in to clear the obstruction as
+the calipers are lifted out. When it is desired to ascertain the
+measurements the leg A is pushed back into place into the slotted
+portion of the guide B, and locked by the clamp screw C. A tool of this
+form is known as an internal transfer caliper.
+
+[Illustration: Fig. 174.--Common Forms of Inside and Outside Calipers.]
+
+The form of caliper shown at B is an outside caliper. Those at C and D
+are special forms for inside and outside work, the former being used,
+if desired, as a divider, while the latter may be employed for measuring
+the walls of tubing. The calipers at E are simple forms, having a
+friction joint to distinguish them from the spring calipers shown at B,
+C and D. In order to permit of ready adjustment of a spring caliper, a
+split nut as shown at G is sometimes used. A solid nut caliper can only
+be adjusted by screwing the nut in or out on the screw, which may be a
+tedious process if the caliper is to be set from one extreme to the
+other several times in succession. With a slip nut as shown at G it is
+possible to slip it from one end of the thread to the other without
+turning it, and of locking it in place at any desired point by simply
+allowing the caliper leg to come in contact with it. The method of
+adjusting a spring caliper is shown at Fig. 174, H.
+
+Among the most common of the machinist's tools are those used for linear
+measurements. The usual forms are shown in group, Fig. 175. The most
+common tool, which is widely known, is the carpenter's folding two-foot
+rule or the yardstick. While these are very convenient for taking
+measurements where great accuracy is not required, the machinist must
+work much more accurately than the carpenter, and the standard steel
+scale which is shown at D, is a popular tool for the machinist. The
+steel scale is in reality a graduated straight edge and forms an
+important part of various measuring tools. These are made of high grade
+steel and vary from 1 to 48 inches in length. They are carefully
+hardened in order to preserve the graduations, and all surfaces and
+edges are accurately ground to insure absolute parallelism. The
+graduations on the high grade scales are produced with a special device
+known as a dividing engine, but on cheaper scales, etching suffices to
+provide a fairly accurate graduation. The steel scales may be very thin
+and flexible, or may be about an eighth of an inch thick on the
+twelve-inch size, which is that commonly used with combination squares,
+protractors and other tools of that nature. The repairman's scale
+should be graduated both with the English system, in which the inches
+are divided into eighths, sixteenths, thirty-secondths and
+sixty-fourths, and also in the metric system, divided into millimeters
+and centimeters. Some machinists use scales graduated in tenths,
+twentieths, fiftieths and hundredths. This is not as good a system of
+graduation as the more conventional one first described.
+
+[Illustration: Fig. 175.--Measuring Appliances for the Machinist and
+Floor Man.]
+
+Some steel scales are provided with a slot or groove cut the entire
+length on one side and about the center of the scales. This permits the
+attachment of various fittings such as the protractor head, which
+enables the machinist to measure angles, or in addition the heads
+convert the scale into a square or a tool permitting the accurate
+bisecting of pieces of circular section. Two scales are sometimes joined
+together to form a right angle, such as shown at Fig. 175, C. This is
+known as a square and is very valuable in ascertaining the truth of
+vertical pieces that are supposed to form a right angle with a base
+piece.
+
+The Vernier is a device for reading finer divisions on a scale than
+those into which the scale is divided. Sixty-fourths of an inch are
+about the finest division that can be read accurately with the naked
+eye. When fine work is necessary a Vernier is employed. This consists
+essentially of two rules so graduated that the true scale has each inch
+divided into ten equal parts, the upper or Vernier portion has ten
+divisions occupying the same space as nine of the divisions of the true
+scale. It is evident, therefore, that one of the divisions of the
+Vernier is equal to nine-tenths of one of those on the true scale. If
+the Vernier scale is moved to the right so that the graduations marked
+"1" shall coincide, it will have moved one-tenth of a division on the
+scale or one-hundredth of an inch. When the graduations numbered 5
+coincide the Vernier will have moved five-hundredths of an inch; when
+the lines marked 0 and 10 coincide, the Vernier will have moved
+nine-hundredths of an inch, and when 10 on the Vernier comes opposite 10
+on the scales, the upper rule will have moved ten-hundredths of an inch,
+or the whole of one division on the scale. By this means the scale,
+though it may be graduated only to tenths of an inch, may be accurately
+set at points with positions expressed in hundredths of an inch. When
+graduated to read in thousandths, the true scale is divided into fifty
+parts and the Vernier into twenty parts. Each division of the Vernier
+is therefore equal to nineteen-twentieths of one of the true scale. If
+the Vernier be moved so the lines of the first division coincide, it
+will have moved one-twentieth of one-fiftieth, or .001 inch. The Vernier
+principle can be readily grasped by studying the section of the Vernier
+scale and true scale shown at Fig. 176, A.
+
+[Illustration: Fig. 176.--At Left, Special Form of Vernier Caliper for
+Measuring Gear Teeth; at Right, Micrometer for Accurate Internal
+Measurements.]
+
+The caliper scale which is shown at Fig. 175, A, permits of taking the
+over-all dimension of any parts that will go between the jaws. This
+scale can be adjusted very accurately by means of a fine thread screw
+attached to a movable jaw and the divisions may be divided by eye into
+two parts if one sixty-fourth is the smallest of the divisions. A line
+is indicated on the movable jaw and coincides with the graduations on
+the scale. As will be apparent, if the line does not coincide exactly
+with one of the graduations it will be at some point between the lines
+and the true measurement may be approximated without trouble.
+
+A group of various other measuring tools of value to the machinist is
+shown at Fig. 177. The small scale at A is termed a "center gauge,"
+because it can be used to test the truth of the taper of either a male
+or female lathe center. The two smaller nicks, or v's, indicate the
+shape of a standard thread, and may be used as a guide for grinding the
+point of a thread-cutting tool. The cross level which is shown at B is
+of marked utility in erecting, as it will indicate absolutely if the
+piece it is used to test is level. It will indicate if the piece is
+level along its width as well as its length.
+
+[Illustration: Fig. 177.--Measuring Appliances of Value in Airplane
+Repair Work.]
+
+A very simple attachment for use with a scale that enables the machinist
+to scribe lines along the length of a cylindrical piece is shown at Fig.
+177, C. These are merely small wedge-shaped clamps having an angular
+face to rest upon the bars. The thread pitch gauge which is shown at
+Fig. 177, D, is an excellent pocket tool for the mechanic, as it is
+often necessary to determine without loss of time the pitch of the
+thread on a bolt or in a nut. This consists of a number of leaves having
+serrations on one edge corresponding to the standard thread it is to be
+used in measuring. The tool shown gives all pitches up to 48 threads per
+inch. The leaves may be folded in out of the way when not in use, and
+their shape admits of their being used in any position without the
+remainder of the set interfering with the one in use. The fine pitch
+gauges have slim, tapering leaves of the correct shape to be used in
+finding the pitch of small nuts. As the tool is round when the leaves
+are folded back out of the way, it is an excellent pocket tool, as there
+are no sharp corners to wear out the pocket. Practical application of a
+Vernier having measuring heads of special form for measuring gear teeth
+is shown at Fig. 176, A. As the action of this tool has been previously
+explained, it will not be necessary to describe it further.
+
+
+MICROMETER CALIPERS AND THEIR USE
+
+Where great accuracy is necessary in taking measurements the micrometer
+caliper, which in the simple form will measure easily .001 inch
+(one-thousandth part of an inch) and when fitted with a Vernier that
+will measure .0001 inch (one ten-thousandth part of an inch), is used.
+The micrometer may be of the caliper form for measuring outside
+diameters or it may be of the form shown at Fig. 176, B, for measuring
+internal diameters. The operation of both forms is identical except that
+the internal micrometer is placed inside of the bore to be measured
+while the external form is used just the same as a caliper. The form
+outlined will measure from one and one-half to six and a half inches as
+extension points are provided to increase the range of the instrument.
+The screw has a movement of one-half inch and a hardened anvil is placed
+in the end of the thimble in order to prevent undue wear at that point.
+The extension points or rods are accurately made in standard lengths and
+are screwed into the body of the instrument instead of being pushed in,
+this insuring firmness and accuracy. Two forms of micrometers for
+external measurements are shown at Fig. 178. The top one is graduated
+to read in thousandths of an inch, while the lower one is graduated to
+indicate hundredths of a millimeter. The mechanical principle involved
+in the construction of a micrometer is that of a screw free to move in a
+fixed nut. An opening to receive the work to be measured is provided by
+the backward movement of the thimble which turns the screw and the size
+of the opening is indicated by the graduations on the barrel.
+
+[Illustration: Fig. 178.--Standard Forms of Micrometer Caliper for
+External Measurements.]
+
+The article to be measured is placed between the anvil and spindle, the
+frame being held stationary while the thimble is revolved by the thumb
+and finger. The pitch of the screw thread on the concealed part of the
+spindle is 40 to an inch. One complete revolution of the spindle,
+therefore, moves it longitudinally one-fortieth, or twenty-five
+thousandths of an inch. As will be evident from the development of the
+scale on the barrel of the inch micrometer, the sleeve is marked with
+forty lines to the inch, each of these lines indicating twenty-five
+thousandths. The thimble has a beveled edge which is graduated into
+twenty-five parts. When the instrument is closed the graduation on the
+beveled edge of the thimble marked 0 should correspond to the 0 line on
+the barrel. If the micrometer is rotated one full turn the opening
+between the spindle and anvil will be .025 inch. If the thimble is
+turned only one graduation, or one twenty-fifth of a revolution, the
+opening between the spindle and anvil will be increased only by .001
+inch (one-thousandth of an inch).
+
+As many of the dimensions of the airplane parts, especially of those of
+foreign manufacture or such parts as ball and roller bearings, are based
+on the metric system, the competent repairman should possess both inch
+and metric micrometers in order to avoid continual reference to a table
+of metric equivalents. With a metric micrometer there are fifty
+graduations on the barrel, these representing .01 of a millimeter, or
+approximately .004 inch. One full turn of the barrel means an increase
+of half a millimeter, or .50 mm. (fifty one-hundredths). As it takes two
+turns to augment the space between the anvil and the stem by increments
+of one millimeter, it will be evident that it would not be difficult to
+divide the spaces on the metric micrometer thimble in halves by the eye,
+and thus the average workman can measure to .0002 inch plus or minus
+without difficulty. As set in the illustration, the metric micrometers
+show a space of 13.5 mm., or about one millimeter more than half an
+inch. The inch micrometer shown is set to five-tenths or five hundred
+one-thousandths or one-half inch. A little study of the foregoing matter
+will make it easy to understand the action of either the inch or metric
+micrometer.
+
+Both of the micrometers shown have a small knurled knob at the end of
+the barrel. This controls the ratchet stop, which is a device that
+permits a ratchet to slip by a pawl when more than a certain amount of
+pressure is applied, thereby preventing the measuring spindle from
+turning further and perhaps springing the instrument. A simple rule that
+can be easily memorized for reading the inch micrometer is to multiply
+the number of vertical divisions on the sleeve by 25 and add to that the
+number of divisions on the bevel of the thimble reading from the zero to
+the line which coincides with the horizontal line on the sleeve. For
+example: if there are ten divisions visible on the sleeve, multiply this
+number by 25, then add the number of divisions shown on the bevel of the
+thimble, which is 10. The micrometer is therefore opened 10 x 25 equals
+250 plus 10 equals 260 thousandths.
+
+Micrometers are made in many sizes, ranging from those having a maximum
+opening of one inch to special large forms that will measure forty or
+more inches. While it is not to be expected that the repairman will have
+use for the big sizes, if a caliper having a maximum opening of six
+inches is provided with a number of extension rods enabling one to
+measure smaller objects, practically all of the measuring needed in
+repairing engine parts can be made accurately. Two or three smaller
+micrometers having a maximum range of two or three inches will also be
+found valuable, as most of the measurements will be made with these
+tools which will be much easier to handle than the larger sizes.
+
+
+TYPICAL TOOL OUTFITS
+
+The equipment of tools necessary for repairing airplane engines depends
+entirely upon the type of the power plant and while the common hand
+tools can be used on all forms, the work is always facilitated by having
+special tools adapted for reaching the nuts and screws that would be
+hard to reach otherwise. Special spanners and socket wrenches are very
+desirable. Then again, the nature of the work to be performed must be
+taken into consideration. Rebuilding or overhauling an engine calls for
+considerably more tools than are furnished for making field repairs or
+minor adjustments. A complete set of tools supplied to men working on
+Curtiss OX-2 engines and JN-4 training biplanes is shown at Fig. 179.
+The tools are placed in a special box provided with a hinged cover and
+are arranged in the systematic manner outlined. The various tools and
+supplies shown are: A, hacksaw blades; B, special socket wrenches for
+engine bolts and nuts; C, ball pein hammers, four sizes; D, five
+assorted sizes of screw drivers ranging from very long for heavy work to
+short and small for fine work; E, seven pairs of pliers including
+combination in three sizes, two pairs of cutting pliers and one round
+nose; F, two split pin extractors and spreaders; G, wrench set including
+three adjustable monkey wrenches, one Stillson or pipe wrench, five
+sizes adjustable end wrenches and ten double end S wrenches; H, set of
+files, including flat, three cornered and half round; I, file brush; J,
+chisel and drift pin; K, three small punches or drifts; L, hacksaw
+frame; M, soldering copper; N, special spanners for propeller retaining
+nuts; O, special spanners; P, socket wrenches, long handle; Q, long
+handle, stiff bristle brushes for cleaning motor; R, gasoline blow
+torch; S, hand drill; T, spools of safety wire; U, flash lamp; V,
+special puller and castle wrenches; W, oil can; X, large adjustable
+monkey wrench; Y, washer and gasket cutter; Z, ball of heavy twine. In
+addition to the tools, various supplies, such as soldering acid, solder,
+shellac, valve grinding compound, bolts and nuts, split pins, washers,
+wood screws, etc., are provided.
+
+[Illustration: Fig. 179.--Special Tools for Maintaining Curtiss OX-2
+Motor Used in Curtiss JN-4 Training Biplane.]
+
+
+SPECIAL HALL-SCOTT TOOLS
+
+  NO.             TOOL                        DIRECTIONS FOR USE
+   1  Engine hoisting hook, 6-cylinder  Hook under cam-shaft housing,
+                                        when hoisting engine.
+   2  Engine hoisting hook, 4-cylinder  Hook under cam-shaft housing,
+                                        when hoisting engine.
+   3  Water plug wrench                 For use on water plugs on top
+                                        and end of cylinders.
+   4  Vertical shaft flange puller      For pulling lower pinion shaft
+                                        flange from shaft. (Used on A-5
+                                        and A-7 engines only.)
+   5  Oil gun                           For general lubrication use.
+   6  Magneto gear puller               For pulling magneto gears from
+                                        magneto shaft.
+   7  Socket wrench, 1/4" A.L.A.M.      For use on bolts and nuts on
+                                        crank cases.
+   8  Socket wrench, 1/4" A.L.A.M       For use on crank cases and
+                                        magneto gear housings.
+   9  Socket wrench, 1/4" A.L.A.M.      For use on magneto gear
+                                        housings.
+  10  Socket wrench, 3/8" standard      For bolts and nuts which fasten
+                                        magnetos to crank-case.
+  11  Socket wrench, 1/4" A.L.A.M.      For use on magneto gear
+                                        housings.
+  12  Vertical shaft gear puller        For removing water pump and
+                                        magneto drive gear.
+  13  Brace and facing cutter           For facing lugs on cylinders for
+                                        cylinder hold down stud washers.
+  14  Handle for brace                  Use with brace.
+  15  Valve grinding brace              For grinding in valves.
+  16  Socket wrench base, 3/8" A.L.A.M. For thrust bearing cap screws.
+  17  Brace and facing cutter, 5/16"    For facing lugs on rocker arm
+      A.L.A.M.                          covers.
+  18  Valve grinding screw driver       For grinding in valves.
+  19  Valve spring tool                 For putting on and taking off
+                                        valve springs.
+  20  Block-valve spring tool           For use with valve spring tool.
+  21  Socket wrench, 5/8" A.L.A.M.      For main bearing nuts.
+  22  Socket wrench, 1/4" A.L.A.M.      For use on cam-shaft housing.
+  23  Socket wrench, 5/16" A.L.A.M.     For cam-shaft housing hold down
+                                        stud nuts.
+  24  Socket wrench, 1/2" A.L.A.M.      For cylinder hold down stud
+                                        nuts.
+  25  Socket wrench, 5/16" A.L.A.M.     For carburetor and water pump
+                                        bolts and nuts.
+  26  Socket wrench, 5/16" A.L.A.M.     For carburetor and water pump
+                                        bolts and nuts.
+  27  Socket wrench                     For use on carburetor jets.
+  28  Magneto screw driver              For general magneto use.
+  29  Brass bar, 1" diameter x 7" long  For driving piston pins from
+                                        pistons.
+  30  Hack saw                          For general use.
+  31  Oil can                           For cam-shaft housing
+                                        lubrication.
+  32  Gasoline or distillate can        For priming or other use.
+  33  Oil can                           For magneto gear lubrication.
+  34  Shellac can                       For rubber hose connections and
+                                        gaskets.
+  35  Magneto cleaner                   For use on magnetos.
+  36  Clamps                            For holding cylinder hold down
+                                        studs, when fitting main
+                                        bearings.
+  37  Piston guards                     For use in pistons, when out of
+                                        engine, to protect them.
+  38  Screw driver                      For general use.
+  39  Vertical shaft clamps             For clamping vertical shaft
+                                        flanges, when timing engine.
+  40  Thrust adjusting nut wrench       For adjusting propeller thrust
+                                        bearing.
+  41  Stuffing box spanner wrench       For adjusting stuffing box nut
+                                        on vertical shaft.
+  42  Water pump spanner wrench         For adjusting water pump
+                                        stuffing nut.
+  43  Wrench                            For use on cylinder relief cocks
+                                        and cylinder priming cocks.
+  44  Hose clamp wrench                 For use on hose clamps.
+  45  Scraper                           For cleaning piston ring grooves
+                                        on pistons.
+  46  Crank-shaft nut wrench            For adjusting crank-shaft nut.
+  47  Spark-plug wrench                 For putting in and taking out
+                                        spark-plugs in cylinders.
+  48  Timing disc (single disc)         For use on crank-shaft to time
+                                        engine.
+      Specify type motor disc should be made for. If double disc is
+      required, specify the two types of motors the disc is to be made
+      for. Double disc.
+  49  Main bearing scraper              For scraping in bearings.
+  50  Cylinder carbon scraper           For removing carbon from heads
+                                        of cylinders.
+  51  Valve seating tool                For seating valves in cylinder
+                                        heads.
+  52  Scraper, small                    For general bearing use.
+  53  Scraper, large                    For general bearing use.
+  54  Crank-shaft flange puller         For pulling crank-shaft flange
+                                        from crank-shaft.
+  55  Piston and connecting rod racks.
+  56  Main bearing stud nuts and shim
+      rack.
+  57  Main bearing board rack.
+  58  Rocker arm and cover rack.
+
+The special tools and fixtures recommended by the Hall-Scott Company for
+work on their engines are clearly shown at Fig. 180. All tools are
+numbered and their uses may be clearly understood by reference to the
+illustration and explanatory list given on pages 410 and 411.
+
+
+OVERHAULING AIRPLANE ENGINES
+
+After an airplane engine has been in use for a period ranging from 60 to
+80 hours, depending upon the type, it is necessary to give it a thorough
+overhauling before it is returned to service. To do this properly, the
+engine is removed from the fuselage and placed on a special supporting
+stand, such as shown at Fig. 181, so it can be placed in any position
+and completely dismantled. With a stand of this kind it is as easy to
+work on the bottom of the engine as on the top and every part can be
+instantly reached. The crank-case shown in place in illustration is in a
+very convenient position for scraping in the crank-shaft bearings.
+
+[Illustration: Fig. 180.--Special Tools and Appliances to Facilitate
+Overhauling Work on Hall-Scott Airplane Engines.]
+
+In order to look over the parts of an engine and to restore the worn or
+defective components it is necessary to take the engine entirely apart,
+as it is only when the power plant is thoroughly dismantled that the
+parts can be inspected or measured to determine defects or wear. If one
+is not familiar with the engine to be inspected, even though the work is
+done by a repairman of experience, it will be found of value to take
+certain precautions when dismantling the engine in order to insure that
+all parts will be replaced in the same position they occupied before
+removal. There are a number of ways of identifying the parts, one of the
+simplest and surest being to mark them with steel numbers or letters or
+with a series of center punch marks in order to retain the proper
+relation when reassembling. This is of special importance in connection
+with dismantling multiple cylinder engines as it is vital that pistons,
+piston rings, connecting rods, valves, and other cylinder parts be
+always replaced in the same cylinder from which they were removed,
+because it is uncommon to find equal depreciation in all cylinders. Some
+repairmen use small shipping tags to identify the pieces. This can be
+criticised because the tags may become detached and lost and the
+identity of the piece mistaken. If the repairing is being done in a shop
+where other engines of the same make are being worked on, the repairman
+should be provided with a large chest fitted with a lock and key in
+which all of the smaller parts, such as rods, bolts and nuts, valves,
+gears, valve springs, cam-shafts, etc., may be stored to prevent the
+possibility of confusion with similar members of other engines. All
+parts should be thoroughly cleaned with gasoline or in the potash kettle
+as removed, and wiped clean and dry. This is necessary to show wear
+which will be evidenced by easily identified indications in cases where
+the machine has been used for a time, but in others, the deterioration
+can only be detected by delicate measuring instruments.
+
+[Illustration: Fig. 181.--Special Stand to Make Motor Overhauling Work
+Easier.]
+
+In taking down a motor the smaller parts and fittings such as
+spark-plugs, manifolds and wiring should be removed first. Then the more
+important members such as cylinders may be removed from the crank-case
+to give access to the interior and make possible the examination of the
+pistons, rings and connecting rods. After the cylinders are removed the
+next operation is to disconnect the connecting rods from the crank-shaft
+and to remove them and the pistons attached as a unit. Then the
+crank-case is dismembered, in most cases by removing the bottom half or
+oil sump, thus exposing the main bearings and crank-shaft. The first
+operation is the removal of the inlet and exhaust manifolds. In some
+cases the manifolds are cored integral with the cylinder head casting
+and it is merely necessary to remove a short pipe leading from the
+carburetor to one inlet opening and the exhaust pipe from the outlet
+opening common to all cylinders. In order to remove the carburetor it is
+necessary to shut off the gasoline supply at the tank and to remove the
+pipe coupling at the float chamber. It is also necessary to disconnect
+the throttle operating rod. After the cylinders are removed and before
+taking the crank-case apart it is well to remove the water pump and
+magneto. The wiring on most engines of modern development is carried in
+conduits and usually releasing two or three minor fastenings will permit
+one to take off the plug wiring as a unit. The wire should be
+disconnected from both spark-plugs and magneto distributor before its
+removal. When the cylinders are removed, the pistons, piston rings, and
+connecting rods are clearly exposed and their condition may be readily
+noticed.
+
+Before disturbing the arrangement of the timing gears, it is important
+that these be marked so that they will be replaced in exactly the same
+relation as intended by the engine designer. If the gears are properly
+marked the valve timing and magneto setting will be undisturbed when the
+parts are replaced after overhauling. With the cylinders off, it is
+possible to ascertain if there is any undue wear present in the
+connecting rod bearings at either the wrist pin or crank-pin ends and
+also to form some idea of the amount of carbon deposits on the piston
+top and back of the piston rings. Any wear of the timing gears can also
+be determined. The removal of the bottom plate of the engine enables the
+repairman to see if the main bearings are worn unduly. Often bearings
+may be taken up sufficiently to eliminate all looseness. In other cases
+they may be worn enough so that careful refitting will be necessary.
+Where the crank-case is divided horizontally into two portions, the
+upper one serving as an engine base to which the cylinders and in fact
+all important working parts are attached, the lower portion performs the
+functions of an oil container and cover for the internal mechanism. This
+is the construction generally followed.
+
+
+DEFECTS IN CYLINDERS
+
+After the cylinders have been removed and stripped of all fittings, they
+should be thoroughly cleaned and then carefully examined for defects.
+The interior or bore should be looked at with a view of finding score
+marks, grooves, cuts or scratches in the interior, because there are
+many faults that may be ascribed to depreciation at this point. The
+cylinder bore may be worn out of round, which can only be determined by
+measuring with an internal caliper or dial indicator even if the
+cylinder bore shows no sign of wear. The flange at the bottom of the
+cylinder by which it is held to the engine base may be cracked. The
+water jacket wall may have opened up due to freezing of the jacket
+water at some time or other or it may be filled with scale and sediment
+due to the use of impure cooling water. The valve seat may be scored or
+pitted, while the threads holding the valve chamber cap may be worn so
+that the cap will not be a tight fit. The detachable head construction
+makes it possible to remove that member and obtain ready access to the
+piston tops for scraping out carbon without taking the main cylinder
+portion from the crank-case. When the valves need grinding the head may
+be removed and carried to the bench where the work may be performed with
+absolute assurance that none of the valve grinding compound will
+penetrate into the interior of the cylinder as is sometimes unavoidable
+with the I-head cylinder. If the cylinder should be scored, the water
+jacket and combustion head may be saved and a new cylinder casting
+purchased at considerably less cost than that of the complete unit
+cylinder.
+
+The detachable head construction has only recently been applied on
+airplane engines, though it was one of the earliest forms of automobile
+engine construction. In the early days it was difficult to procure
+gaskets or packings that would be both gas and water tight. The sheet
+asbestos commonly used was too soft and blew out readily. Besides a new
+gasket had to be made every time the cylinder head was removed. Woven
+wire and asbestos packings impregnated with rubber, red lead, graphite
+and other filling materials were more satisfactory than the soft sheet
+asbestos, but were prone to burn out if the water supply became low.
+Materials such as sheet copper or brass proved to be too hard to form a
+sufficiently yielding packing medium that would allow for the inevitable
+slight inaccuracies in machining the cylinder head and cylinder. The
+invention of the copper-asbestos gasket, which is composed of two sheets
+of very thin, soft copper bound together by a thin edging of the same
+material and having a piece of sheet asbestos interposed solved this
+problem. Copper-asbestos packings form an effective seal against leakage
+of water and a positive retention means for keeping the explosion
+pressure in the cylinder. The great advantage of the detachable head is
+that it permits of very easy inspection of the piston tops and
+combustion chamber and ready removal of carbon deposits.
+
+
+CARBON DEPOSITS, THEIR CAUSE AND PREVENTION
+
+Most authorities agree that carbon is the result of imperfect combustion
+of the fuel and air mixture as well as the use of lubricating oils of
+improper flash point. Lubricating oils that work by the piston rings may
+become decomposed by the great heat in the combustion chamber, but at
+the same time one cannot blame the lubricating oil for all of the carbon
+deposits. There is little reason to suspect that pure petroleum oil of
+proper body will deposit excessive amounts of carbon, though if the oil
+is mixed with castor oil, which is of vegetable origin, there would be
+much carbon left in the interior of the combustion chamber. Fuel
+mixtures that are too rich in gasoline also produce these undesirable
+accumulations.
+
+A very interesting chemical analysis of a sample of carbon scraped from
+the interior of a motor vehicle engine shows that ordinarily the
+lubricant is not as much to blame as is commonly supposed. The analysis
+was as follows:
+
+  Oil                          14.3%
+  Other combustible matter     17.9
+  Sand, clay, etc.             24.8
+  Iron oxide                   24.5
+  Carbonate of lime             8.9
+  Other constituents            9.6
+
+It is extremely probable that the above could be divided into two
+general classes, these being approximately 32.2% oil and combustible
+matter and a much larger proportion, or 67.8% of earthy matter. The
+presence of such a large percentage of earthy matter is undoubtedly due
+to the impurities in the air, such as road dust which has been sucked
+in through the carburetor. The fact that over 17% of the matter which is
+combustible was not of an oily nature lends strong support to this view.
+There would not be the amount of earthy material present in the carbon
+deposits of an airplane engine as above stated because the air is almost
+free from dust at the high altitudes planes are usually flown. One could
+expect to find more combustible and less earthy matter and the carbon
+would be softer and more easily removed. It is very good practice to
+provide a screen on the air intake to reduce the amounts of dust sucked
+in with the air as well as observing the proper precautions relative to
+supplying the proper quantities of air to the mixture and of not using
+any more oil than is needed to insure proper lubrication of the internal
+mechanism.
+
+
+USE OF CARBON SCRAPERS
+
+It is not unusual for one to hear an aviator complain that the engine he
+operates is not as responsive as it was when new after he has run it but
+relatively few hours. There does not seem to be anything actually wrong
+with the engine, yet it does not respond readily to the throttle and is
+apt to overheat. While these symptoms denote a rundown condition of the
+mechanism, the trouble is often due to nothing more serious than
+accumulations of carbon. The remedy is the removal of this matter out of
+place. The surest way of cleaning the inside of the motor thoroughly is
+to remove the cylinders, if these members are cast integrally with the
+head or of removing the head member if that is a separate casting, to
+expose all parts.
+
+In certain forms of cylinders, especially those of the L form, it is
+possible to introduce simple scrapers down through the valve chamber cap
+holes and through the spark-plug hole if this component is placed in the
+cylinder in some position that communicates directly to the interior of
+the cylinder or to the piston top. No claim can be made for originality
+or novelty of this process as is has been used for many years on large
+stationary engines. The first step is to dismantle the inlet and exhaust
+piping and remove the valve caps and valves, although if the deposit is
+not extremely hard or present in large quantities one can often
+manipulate the scrapers in the valve cap openings without removing
+either the piping or the valves. Commencing with the first cylinder, the
+crank-shaft is turned till the piston is at the top of its stroke, then
+the scraper may be inserted, and the operation of removing the carbon
+started by drawing the tool toward the opening. As this is similar to a
+small hoe, the cutting edge will loosen some of the carbon and will draw
+it toward the opening. A swab is made of a piece of cloth or waste
+fastened at the end of a wire and well soaked in kerosene to clean out
+the cylinder.
+
+When available, an electric motor with a length of flexible shaft and a
+small circular cleaning brush having wire bristles can be used in the
+interior of the engine. The electric motor need not be over one-eighth
+horse-power running 1,200 to 1,600 R. P. M., and the wire brush must, of
+course, be of such size that it can be easily inserted through the valve
+chamber cap. The flexible shaft permits one to reach nearly all parts of
+the cylinder interior without difficulty and the spreading out and
+flattening of the brush insures that considerable surface will be
+covered by that member.
+
+
+BURNING OUT CARBON WITH OXYGEN
+
+A process of recent development that gives very good results in removing
+carbon without disassembling the motor depends on the process of burning
+out that material by supplying oxygen to support the combustion and to
+make it energetic. A number of concerns are already offering apparatus
+to accomplish this work, and in fact any shop using an autogenous
+welding outfit may use the oxygen tank and reducing valve in connection
+with a simple special torch for burning the carbon. Results have
+demonstrated that there is little danger of damaging the motor parts,
+and that the cost of oxygen and labor is much lower than the old method
+of removing the cylinders and scraping the carbon out, as well as being
+very much quicker than the alternative process of using carbon solvent.
+The only drawback to this system is that there is no absolute insurance
+that every particle of carbon will be removed, as small protruding
+particles may be left at points that the flame does not reach and cause
+pre-ignition and consequent pounding, even after the oxygen treatment.
+It is generally known that carbon will burn in the presence of oxygen,
+which supports combustion of all materials, and this process takes
+advantage of this fact and causes the gas to be injected into the
+combustion chamber over a flame obtained by a match or wax taper.
+
+[Illustration: Fig. 182.--Showing Where Carbon Deposits Collect in
+Engine Combustion Chamber, and How to Burn Them Out with the Aid of
+Oxygen. A--Special Torch. B--Torch Coupled to Oxygen Tank. C--Torch in
+Use.]
+
+It is suggested by those favoring this process that the night before the
+oxygen is to be used the engine be given a conventional kerosene
+treatment. A half tumbler full of this liquid or of denatured alcohol is
+to be poured into each cylinder and permitted to remain there over
+night. As a precaution against fire, the gasoline is shut off from the
+carburetor before the torch is inserted in the cylinder and the motor
+started so that the gasoline in the pipe and carburetor float chamber
+will be consumed. Work is done on one cylinder at a time. A note of
+caution was recently sounded by a prominent spark-plug manufacturer
+recommending that the igniter member be removed from the cylinder in
+order not to injure it by the heat developed. The outfits on the market
+consist of a special torch having a trigger controlled valve and a
+length of flexible tubing such as shown at Fig. 182, A, and a regulating
+valve and oxygen tank as shown at B. The gauge should be made to
+register about twelve pounds pressure.
+
+The method of operation is very simple and is outlined at C. The burner
+tube is placed in the cylinder and the trigger valve is opened and the
+oxygen permitted to circulate in the combustion chamber. A lighted match
+or wax taper is dropped in the chamber and the injector tube is moved
+around as much as possible so as to cover a large area. The carbon takes
+fire and burns briskly in the presence of the oxygen. The combustion of
+the carbon is accompanied by sparks and sometimes by flame if the
+deposit is of an oily nature. Once the carbon begins to burn the
+combustion continues without interruption as long as the oxygen flows
+into the cylinder. Full instructions accompany each outfit and the
+amount of pressure for which the regulator should be set depends upon
+the design of the torch and the amount of oxygen contained in the
+storage tank.
+
+
+REPAIRING SCORED CYLINDERS
+
+If the engine has been run at any time without adequate lubrication, one
+or more of the cylinders may be found to have vertical scratches running
+up and down the cylinder walls. The depth of these will vary according
+to the amount of time the cylinder was without lubrication, and if the
+grooves are very deep the only remedy is to purchase a new member. Of
+course, if sufficient stock is available in the cylinder walls, the
+cylinders may be rebored and new pistons which are oversize, _i.e._,
+larger than standard, may be fitted. Where the scratches are not deep
+they may be ground out with a high speed emery wheel or lapped out if
+that type of machine is not available. Wrist pins have been known to
+come loose, especially when these are retained by set screws that are
+not properly locked, and as wrist-pins are usually of hardened steel it
+will be evident that the sharp edge of that member can act as a cutting
+tool and make a pronounced groove in the cylinder. Cylinder grinding is
+a job that requires skilled mechanics, but may be accomplished on any
+lathe fitted with an internal grinding attachment. While automobile
+engine cylinders usually have sufficient wall thickness to stand
+reboring, those of airplane engines seldom have sufficient metal to
+permit of enlarging the bore very much by a boring tool. A few
+thousandths of an inch may be ground out without danger, however. An
+airplane engine cylinder with deep grooves must be scrapped as a general
+rule.
+
+Where the grooves in the cylinder are not deep or where it has warped
+enough so the rings do not bear equally at all parts of the cylinder
+bore, it is possible to obtain a fairly accurate degree of finish by a
+lapping process in which an old piston is coated with a mixture of fine
+emery and oil and is reciprocated up and down in the cylinder as well as
+turned at the same time. This may be easily done by using a dummy
+connecting rod having only a wrist pin end boss, and of such size at the
+other end so that it can be held in the chuck of a drill press. The
+cylinder casting is firmly clamped on the drill press table by suitable
+clamping blocks, and a wooden block is placed in the combustion chamber
+to provide a stop for the piston at its lower extreme position. The back
+gears are put in and the drill chuck is revolved slowly. All the while
+that the piston is turning the drill chuck should be raised up and down
+by the hand feed lever, as the best results are obtained when the
+lapping member is given a combination of rotary and reciprocating
+motion.
+
+
+VALVE REMOVAL AND INSPECTION
+
+One of the most important parts of the gasoline engine and one that
+requires frequent inspection and refitting to keep in condition, is the
+mushroom or poppet valve that controls the inlet and exhaust gas flow.
+In overhauling it is essential that these valves be removed from their
+seatings and examined carefully for various defects which will be
+enumerated at proper time. The problem that concerns us now is the best
+method of removing the valve. These are held against the seating in the
+cylinder by a coil spring which exerts its pressure on the cylinder
+casting at the upper end and against a suitable collar held by a key at
+the lower end of the valve stem. In order to remove the valve it is
+necessary to first compress the spring by raising the collar and pulling
+the retaining key out of the valve stem. Many forms of valve spring
+lifters have been designed to permit ready removal of the valves.
+
+When the cylinder is of the valve in-the-head form, the method of valve
+removal will depend entirely upon the system of cylinder construction
+followed. In the Sturtevant cylinder design it is possible to remove the
+head from the cylinder castings and the valve springs may be easily
+compressed by any suitable means when the cylinder head is placed on the
+work bench where it can be easily worked on. The usual method is to
+place the head on a soft cloth with the valves bearing against the
+bench. The valve springs may then be easily pushed down with a simple
+forked lever and the valve stem key removed to release the valve spring
+collar. In the Curtiss OX-2 (see Fig. 182-1/2) and Hall-Scott engines it
+is not possible to remove the valves without taking the cylinder off
+the crank-case, because the valve seats are machined directly in the
+cylinder head and the valve domes are cast integrally with the cylinder.
+This means that if the valves need grinding the cylinder must be removed
+from the engine base to provide access to the valve heads which are
+inside of that member, and which cannot be reached from the outside as
+is true of the L-cylinder construction. In the Curtiss VX engines, the
+valves are carried in detachable cages which may be removed when the
+valves need attention.
+
+[Illustration: Fig. 182-1/2.--Part Sectional View, Showing Valve
+Arrangement in Cylinder of Curtiss OX-2 Aviation Engine.]
+
+
+RESEATING AND TRUING VALVES
+
+Much has been said relative to valve grinding, and despite the mass of
+information given in the trade prints it is rather amusing to watch the
+average repairman or the engine user who prides himself on maintaining
+his own motor performing this essential operation. The common mistakes
+are attempting to seat a badly grooved or pitted valve head on an
+equally bad seat, which is an almost hopeless job, and of using coarse
+emery and bearing down with all one's weight on the grinding tool with
+the hope of quickly wearing away the rough surfaces. The use of improper
+abrasive material is a fertile cause of failure to obtain a satisfactory
+seating. Valve grinding is not a difficult operation if certain
+precautions are taken before undertaking the work. The most important of
+these is to ascertain if the valve head or seat is badly scored or
+pitted. If such is found to be the case no ordinary amount of grinding
+will serve to restore the surfaces. In this event the best thing to do
+is to remove the valve from its seating and to smooth down both the
+valve head and the seat in the cylinder before attempt is made to fit
+them together by grinding. Another important precaution is to make sure
+that the valve stem is straight, and that the head is not warped out of
+shape.
+
+[Illustration: Fig. 183.--Tools for Restoring Valve Head and Seats.]
+
+A number of simple tools is available at the present time for reseating
+valves, these being outlined at Fig. 183. That shown at A is a simple
+fixture for facing off the valve head. The stem is supported by suitable
+bearings carried by the body or shank of the tool, and the head is
+turned against an angularly disposed cutter which is set for the proper
+valve seat angle. The valve head is turned by a screw-driver, the amount
+of stock removed from the head depending upon the location of the
+adjusting screw. Care must be taken not to remove too much metal, only
+enough being taken off to remove the most of the roughness. Valves are
+made in two standard tapers, the angle being either 45 or 60 degrees. It
+is imperative that the cutter blade be set correctly in order that the
+bevel is not changed. A set of valve truing and valve-seat reaming
+cutters is shown at Fig. 183, B. This is adaptable to various size valve
+heads, as the cutter blade D may be moved to correspond to the size of
+the valve head being trued up. These cutter blades are made of tool
+steel and have a bevel at each end, one at 45 degrees, the other at 60
+degrees. The valve seat reamer shown at G will take any one of the heads
+shown at F. It will also take any one of the guide bars shown at H. The
+function of the guide bars is to fit the valve stem bearing in order to
+locate the reamer accurately and to insure that the valve seat is
+machined concentrically with its normal center. Another form of valve
+seat reamer and a special wrench used to turn it is shown at C. The
+valve head truer shown at Fig. 183, D, is intended to be placed in a
+vise and is adaptable to a variety of valve head sizes. The smaller
+valves merely fit deeper in the conical depression. The cutter blade is
+adjustable and the valve stem is supported by a simple self-centering
+bearing. In operation it is intended that the valve stem, which
+protrudes through the lower portion of the guide bearing, shall be
+turned by a drill press or bit stock while the valve head is set against
+the cutter by pressure of a pad carried at the end of a feed screw which
+is supported by a hinged bridge member. This can be swung out of place
+as indicated to permit placing the valve head against the cutter or
+removing it.
+
+As the sizes of valve heads and stems vary considerably a "Universal"
+valve head truing tool must have some simple means of centering the
+valve stem in order to insure concentric machining of the valve head. A
+valve head truer which employs an ingenious method of guiding the valve
+stem is shown at Fig. 183, E. The device consists of a body portion, B,
+provided with an external thread at the top on which the cutter head, A,
+is screwed. A number of steel balls, C, are carried in the grooves which
+may be altered in size by the adjustment nut, F, which screws in the
+bottom of the body portion, B. As the nut F is screwed in against the
+spacer member E, the V-grooves are reduced in size and the steel balls,
+C, are pressed out in contact with the valve stem. As the circle or
+annulus is filled with balls in both upper and lower portions the stem
+may be readily turned because it is virtually supported by ball bearing
+guides. When a larger valve stem is to be supported, the adjusting nut
+F, is screwed out which increases the size of the grooves and permits
+the balls, C, to spread out and allow the larger stem to be inserted.
+
+
+VALVE GRINDING PROCESSES
+
+Mention has been previously made of the importance of truing both valve
+head and seat before attempt is made to refit the parts by grinding.
+After smoothing the valve seat the next step is to find some way of
+turning the valve. Valve heads are usually provided with a screw-driver
+slot passing through the boss at the top of the valve or with two
+drilled holes to take a forked grinding tool. A combination grinding
+tool has been devised which may be used when either the two drilled
+holes or the slotted head form of valve is to be rotated. This consists
+of a special form of screw driver having an enlarged boss just above the
+blade, this boss serving to support a U-shape piece which can be
+securely held in operative position by the clamp screw or which can be
+turned out of the way if the screw driver blade is to be used.
+
+As it is desirable to turn the valve through a portion of a revolution
+and back again rather than turning it always in the same direction, a
+number of special tools has been designed to make this oscillating
+motion possible without trouble. A simple valve grinding tool is shown
+at Fig. 184, C. This consists of a screw-driver blade mounted in a
+handle in such a way that the end may turn freely in the handle. A
+pinion is securely fastened to the screw-driver blade shank, and is
+adapted to fit a race provided with a wood handle and guided by a bent
+bearing member securely fastened to the screw-driver handle. As the rack
+is pushed back and forth the pinion must be turned first in one
+direction and then in the other.
+
+[Illustration: Fig. 184.--Tools and Processes Utilized in Valve
+Grinding.]
+
+A valve grinding tool patterned largely after a breast drill is shown at
+Fig. 184, D. This is worked in such a manner that a continuous rotation
+of the operating crank will result in an oscillating movement of the
+chuck carrying the screw-driver blade. The bevel pinions which are used
+to turn the chuck are normally free unless clutched to the chuck stem by
+the sliding sleeve which must turn with the chuck stem and which carries
+clutching members at each end to engage similar members on the bevel
+pinions and lock these to the chuck stem, one at a time. The bevel gear
+carries a cam-piece which moves the clutch sleeve back and forth as it
+revolves. This means that the pinion giving forward motion of the chuck
+is clutched to the chuck spindle for a portion of a revolution of the
+gear and clutch sleeve is moved back by the cam and clutched to the
+pinion giving a reverse motion of the chuck during the remainder of the
+main drive gear revolution.
+
+It sometimes happens that the adjusting screw on the valve lift plunger
+or the valve lift plunger itself when L head cylinders are used does not
+permit the valve head to rest against the seat. It will be apparent that
+unless a definite space exists between the end of the valve stem and the
+valve lift plunger that grinding will be of little avail because the
+valve head will not bear properly against the abrasive material smeared
+on the valve seat.
+
+The usual methods of valve grinding are clearly outlined at Fig. 184.
+The view at the left shows the method of turning the valve by an
+ordinary screw driver and also shows a valve head at A, having both the
+drilled holes and the screw-driver slot for turning the member and two
+special forms of fork-end valve grinding tools. In the sectional view
+shown at the right, the use of the light spring between the valve head
+and the bottom of the valve chamber to lift the valve head from the seat
+whenever pressure on the grinding tool is released is clearly indicated.
+It will be noted also that a ball of waste or cloth is interposed in the
+passage between the valve chamber and the cylinder interior to prevent
+the abrasive material from passing into the cylinder from the valve
+chamber. When a bitstock is used, instead of being given a true rotary
+motion the chuck is merely oscillated through the greater part of the
+circle and back again. It is necessary to lift the valve from its seat
+frequently as the grinding operation continues; this is to provide an
+even distribution of the abrasive material placed between the valve head
+and its seat. Only sufficient pressure is given to the bitstock to
+overcome the uplift of the spring and to insure that the valve will be
+held against the seat. Where the spring is not used it is possible to
+raise the valve from time to time with the hand which is placed under
+the valve stem to raise it as the grinding is carried on. It is not
+always possible to lift the valve in this manner when the cylinders are
+in place on the engine base owing to the space between the valve lift
+plunger and the end of the valve stem. In this event the use of the
+spring as shown in sectional view will be desirable.
+
+The abrasive generally used is a paste made of medium or fine emery and
+lard oil or kerosene. This is used until the surfaces are comparatively
+smooth, after which the final polish or finish is given with a paste of
+flour emery, grindstone dust, crocus, or ground glass and oil. An
+erroneous impression prevails in some quarters that the valve head
+surface and the seating must have a mirror-like polish. While this is
+not necessary it is essential that the seat in the cylinder and the
+bevel surface of the head be smooth and free from pits or scratches at
+the completion of the operation. All traces of the emery and oil should
+be thoroughly washed out of the valve chamber with gasoline before the
+valve mechanism is assembled and in fact it is advisable to remove the
+old grinding compound at regular intervals, wash the seat thoroughly and
+supply fresh material as the process is in progress.
+
+The truth of seatings may be tested by taking some Prussian blue pigment
+and spreading a thin film of it over the valve seat. The valve is
+dropped in place and is given about one-eighth turn with a little
+pressure on the tool. If the seating is good both valve head and seat
+will be covered uniformly with color. If high spots exist, the heavy
+deposit of color will show these while the low spots will be made
+evident because of the lack of pigment. The grinding process should be
+continued until the test shows an even bearing of the valve head at all
+points of the cylinder seating. When the valves are held in cages it is
+possible to catch the cage in a vise and to turn the valve in any of the
+ways indicated. It is much easier to clean off the emery and oil and
+there is absolutely no danger of getting the abrasive material in the
+cylinder if the construction is such that the valve cage or cylinder
+head member carrying the valve can be removed from the cylinder. When
+valves are held in cages, the tightness of the seat may be tested by
+partially filling the cage with gasoline and noticing how much liquid
+oozes out around the valve head. The degree of moisture present
+indicates the efficacy of the grinding process.
+
+The valves of Curtiss OX-2 cylinders are easily ground in by using a
+simple fixture or tool and working from the top of the cylinder instead
+of from the inside. A tube having a bore just large enough to go over
+the valve stem is provided with a wooden handle or taped at one end and
+a hole of the same size as that drilled through the valve stem is put in
+at the other. To use, the open end of the tube is pushed over the valve
+stem and a split pin pushed through the tube and stem. The valve may be
+easily manipulated and ground in place by oscillating in the customary
+manner.
+
+
+DEPRECIATION IN VALVE OPERATING SYSTEMS
+
+There are a number of points to be watched in the valve operating system
+because valve timing may be seriously interfered with if there is much
+lost motion at the various bearing points in the valve lift mechanism.
+The two conventional methods of opening valves are shown at Fig. 185.
+That at A is the type employed when the valve cages are mounted directly
+in the head, while the form at B is the system used when the valves are
+located in a pocket or extension of the cylinder casting as is the case
+if an L, or T-head cylinder is used. It will be evident that there are
+several points where depreciation may take place. The simplest form is
+that shown at B, and even on this there are five points where lost
+motion may be noted. The periphery of the valve opening cam or roller
+may be worn, though this is not likely unless the roller or cam has
+been inadvertently left soft. The pin which acts as a bearing for the
+roller may become worn, this occurring quite often. Looseness may
+materialize between the bearing surfaces of the valve lift plunger and
+the plunger guide casting, and there may also be excessive clearance
+between the top of the plunger and the valve stem.
+
+[Illustration: Fig. 185.--Outlining Points in Valve Operating Mechanism
+Where Depreciation is Apt to Exist.]
+
+On the form shown at A, there are several parts added to those indicated
+at B. A walking beam or rocker lever is necessary to transform the
+upward motion of the tappet rod to a downward motion of the valve stem.
+The pin on which this member fulcrums may wear as will also the other
+pin acting as a hinge or bearing for the yoke end of the tappet rod. It
+will be apparent that if slight play existed at each of the points
+mentioned it might result in a serious diminution of valve opening.
+Suppose, for example, that there were .005-inch lost motion at each of
+three bearing points, the total lost motion would be .015-inch or
+sufficient to produce noisy action of the valve mechanism. When valve
+plungers of the adjustable form, such as shown at B, are used, the
+hardened bolt head in contact with the end of the valve stem may become
+hollowed out on account of the hammering action at that point. It is
+imperative that the top of this member be ground off true and the
+clearance between the valve stem and plunger properly adjusted. If the
+plunger is a non-adjustable type it will be necessary to lengthen the
+valve stem by some means in order to reduce the excessive clearance. The
+only remedy for wear at the various hinges and bearing pins is to bore
+the holes out slightly larger and to fit new hardened steel pins of
+larger diameter. Depreciation between the valve plunger guide and the
+valve plunger is usually remedied by fitting new plunger guides in place
+of the worn ones. If there is sufficient stock in the plunger guide
+casting as is sometimes the case when these members are not separable
+from the cylinder casting, the guide may be bored out and bushed with a
+light bronze bushing.
+
+A common cause of irregular engine operation is due to a sticking valve.
+This may be owing to a bent valve stem, a weak or broken valve spring or
+an accumulation of burnt or gummed oil between the valve stem and the
+valve stem guide. In order to prevent this the valve stem must be
+smoothed with fine emery cloth and no burrs or shoulders allowed to
+remain on it, and the stem must also be straight and at right angles to
+the valve head. If the spring is weak it may be strengthened in some
+cases by stretching it out after annealing so that a larger space will
+exist between the coils and re-hardening. Obviously if a spring is
+broken the only remedy is replacement of the defective member.
+
+Mention has been made of wear in the valve stem guide and its influence
+on engine action. When these members are an integral part of the
+cylinder the only method of compensating for this wear is to drill the
+guide out and fit a bushing, which may be made of steel tube.
+
+In some engines, especially those of recent development, the valve stem
+guide is driven or screwed into the cylinder casting and is a separate
+member which may be removed when worn and replaced with a new one. When
+the guides become enlarged to such a point that considerable play exists
+between them and the valve stems, they may be easily knocked out or
+unscrewed.
+
+
+PISTON TROUBLES
+
+If an engine has been entirely dismantled it is very easy to examine the
+pistons for deterioration. While it is important that the piston be a
+good fit in the cylinder it is mainly upon the piston rings that
+compression depends. The piston should fit the cylinder with but little
+looseness, the usual practice being to have the piston about .001-inch
+smaller than the bore for each inch of piston diameter at the point
+where the least heat is present or at the bottom of the piston. It is
+necessary to allow more than this at the top of the piston owing to its
+expansion due to the direct heat of the explosion. The clearance is
+usually graduated and a piston that would be .005-inch smaller than the
+cylinder bore at the bottom would be about .0065-inch at the middle and
+.0075-inch at the top. If much more play than this is evidenced the
+piston will "slap" in the cylinder and the piston will be worn at the
+ends more than in the center. Aluminum or alloy pistons require more
+clearance than cast iron ones do, usually 1.50 times as much. Pistons
+sometimes warp out of shape and are not truly cylindrical. This results
+in the high spots rubbing on the cylinder while the low spots will be
+blackened where a certain amount of gas has leaked by.
+
+Mention has been previously made of the necessity of reboring or
+regrinding a cylinder that has become scored or scratched and which
+allows the gas to leak by the piston rings. When the cylinder is ground
+out, it is necessary to use a larger piston to conform to the enlarged
+cylinder bore. Most manufacturers are prepared to furnish over-size
+pistons, there being four standard over-size dimensions adopted by the
+S. A. E. for rebored cylinders. These are .010-inch, .020-inch,
+.030-inch, and .040-inch larger than the original bore.
+
+The piston rings should be taken out of the piston grooves and all
+carbon deposits removed from the inside of the ring and the bottom of
+the groove. It is important to take this deposit out because it prevents
+the rings from performing their proper functions by reducing the ring
+elasticity, and if the deposit is allowed to accumulate it may
+eventually result in sticking and binding of the ring, this producing
+excessive friction or loss of compression. When the rings are removed
+they should be tested to see if they retain their elasticity and it is
+also well to see that the small pins in some pistons which keep the
+rings from turning around so the joints will not come in line are still
+in place. If no pins are found there is no cause for alarm because these
+dowels are not always used. When fitted, they are utilized with rings
+having a butt joint or diagonal cut as the superior gas retaining
+qualities of the lap or step joint render the pins unnecessary.
+
+If gas has been blowing by the ring or if these members have not been
+fitting the cylinder properly the points where the gas passed will be
+evidenced by burnt, brown or roughened portions of the polished surface
+of the pistons and rings. The point where this discoloration will be
+noticed more often is at the thin end of an eccentric ring, the
+discoloration being present for about 1/2-inch or 3/4-inch each side of
+the slot. It may be possible that the rings were not true when first
+put in. This made it possible for the gas to leak by in small amounts
+initially which increased due to continued pressure until quite a large
+area for gas escape had been created.
+
+
+PISTON RING MANIPULATION
+
+Removing piston rings without breaking them is a difficult operation if
+the proper means are not taken, but is a comparatively simple one when
+the trick is known. The tools required are very simple, being three
+strips of thin steel about one-quarter inch wide and four or five inches
+long and a pair of spreading tongs made up of one-quarter inch diameter
+keystock tied in the center with a copper wire to form a hinge. The
+construction is such that when the hand is closed and the handles
+brought together the other end of the expander spreads out, an action
+just opposite to that of the conventional pliers. The method of using
+the tongs and the metal strips is clearly indicated at Fig. 186. At A
+the ring expander is shown spreading the ends of the rings sufficiently
+to insert the pieces of sheet metal between one of the rings and the
+piston. Grasp the ring as shown at B, pressing with the thumbs on the
+top of the piston and the ring will slide off easily, the thin metal
+strips acting as guide members to prevent the ring from catching in the
+other piston grooves. Usually no difficulty is experienced in removing
+the top or bottom rings, as these members may be easily expanded and
+worked off directly without the use of a metal strip. When removing the
+intermediate rings, however, the metal strips will be found very useful.
+These are usually made by the repairman by grinding the teeth from old
+hacksaw blades and rounding the edges and corners in order to reduce the
+liability of cutting the fingers. By the use of the three metal strips a
+ring is removed without breaking or distorting it and practically no
+time is consumed in the operation.
+
+
+FITTING PISTON RINGS
+
+Before installing new rings, they should be carefully fitted to the
+grooves to which they are applied. The tools required are a large piece
+of fine emery cloth, a thin, flat file, a small vise with copper or
+leaden jaw clips, and a smooth hard surface such as that afforded by the
+top of a surface plate or a well planed piece of hard wood. After making
+sure that all deposits of burnt oil and carbon have been removed from
+the piston grooves, three rings are selected, one for each groove. The
+ring is turned all around its circumference into the groove it is to
+fit, which can be done without springing it over the piston as the
+outside edge of the ring may be used to test the width of the groove
+just as well as the inside edge. The ring should be a fair fit and while
+free to move circumferentially there should be no appreciable up and
+down motion. If the ring is a tight fit it should be laid edge down upon
+the piece of emery cloth which is placed on the surface plate and
+carefully rubbed down until it fits the groove it is to occupy. It is
+advisable to fit each piston ring individually and to mark them in some
+way to insure that they will be placed in the groove to which they are
+fitted.
+
+The repairman next turns his attention to fitting the ring in the
+cylinder itself. The ring should be pushed into the cylinder at least
+two inches up from the bottom and endeavor should be made to have the
+lower edge of the ring parallel with the bottom of the cylinder. If the
+ring is not of correct diameter, but is slightly larger than the
+cylinder bore, this condition will be evident by the angular slots of
+the rings being out of line or by difficulty in inserting the ring if it
+is a lap joint form. If such is the case the ring is removed from the
+cylinder and placed in the vise between soft metal jaw clips. Sufficient
+metal is removed with a fine file from the edges of the ring at the slot
+until the edges come into line and a slight space exists between them
+when the ring is placed into the cylinder. It is important that this
+space be left between the ends, for if this is not done when the ring
+becomes heated the expansion of metal may cause the ends to abut and the
+ring to jam in the cylinder.
+
+[Illustration: Fig. 186.--Method of Removing Piston Rings, and Simple
+Clamp to Facilitate Insertion of Rings in Cylinder.]
+
+It is necessary to use more than ordinary caution in replacing the rings
+on the piston because they are usually made of cast iron, a metal that
+is very fragile and liable to break because of its brittleness. Special
+care should be taken in replacing new rings as these members are more
+apt to break than old ones. This is probably accounted for by the
+heating action on used rings which tends to anneal the metal as well as
+making it less springy. The bottom ring should be placed in position
+first which is easily accomplished by springing the ring open enough to
+pass on the piston and then sliding it into place in the lower groove
+which on some types of engines is below the wrist pin, whereas in others
+all grooves are above that member. The other members are put in by a
+reversal of the process outlined at Fig. 186, A and B. It is not always
+necessary to use the guiding strips of metal when replacing rings as it
+is often possible, by putting the rings on the piston a little askew and
+maneuvering them to pass the grooves without springing the ring into
+them. The top ring should be the last one placed in position.
+
+Before placing pistons in the cylinder one should make sure that the
+slots in the piston rings are spaced equidistant on the piston, and if
+pins are used to keep the ring from turning one should be careful to
+make sure that these pins fit into their holes in the ring and that they
+are not under the ring at any point. Practically all cylinders are
+chamfered at the lower end to make insertion of piston rings easier. The
+operation of putting on a cylinder casting over a piston really requires
+two pairs of hands, one to manipulate the cylinder, the other person to
+close the rings as they enter the cylinder. This may be done very easily
+by a simple clamp member made of sheet brass or iron and used to close
+the ring as indicated at Fig. 186, C. It is apparent that the clamp must
+be adjusted to each individual ring and that the split portion of the
+clamp must coincide with the split portion of the ring. The cylinder
+should be well oiled before any attempt is made to install the pistons.
+The engine should be run with more than the ordinary amount of lubricant
+for several hours after new piston rings have been inserted. On first
+starting the engine, one may be disappointed in that the compression is
+even less than that obtained with the old rings. This condition will
+soon be remedied as the rings become polished and adapt themselves to
+the contour of the cylinder.
+
+
+WRIST PIN WEAR
+
+While wrist pins are usually made of very tough steel, case hardened
+with the object of wearing out an easily renewable bronze bushing in the
+upper end of the connecting rod rather than the wrist pin it sometimes
+happens that these members will be worn so that even the replacement of
+a new bushing in the connecting rod will not reduce the lost motion and
+attendant noise due to a loose wrist pin. The only remedy is to fit new
+wrist pins to the piston. Where the connecting rod is clamped to the
+wrist pin and that member oscillates in the piston bosses the wear will
+usually be indicated on bronze bushings which are pressed into the
+piston bosses. These are easily renewed and after running a reamer
+through them of the proper size no difficulty should be experienced in
+replacing either the old or a new wrist pin depending upon the condition
+of that member. If no bushings are provided, as in alloy pistons, the
+bosses can sometimes be bored out and thin bushings inserted, though
+this is not always possible. The alternative is to ream out the bosses
+and upper end of rod a trifle larger after holes are trued up and fit
+oversize wrist pins.
+
+
+INSPECTION AND REFITTING OF ENGINE BEARINGS
+
+While the engine is dismantled one has an excellent opportunity to
+examine the various bearing points in the engine crank-case to ascertain
+if any looseness exists due to depreciation of the bearing surfaces. As
+will be evident, both main crank-shaft bearings and the lower end of the
+connecting rods may be easily examined for deterioration. With the rods
+in place, it is not difficult to feel the amount of lost motion by
+grasping the connecting rod firmly with the hand and moving it up and
+down. After the connecting rods have been removed and the propeller hub
+taken off the crank-shaft to permit of ready handling, any looseness in
+the main bearing may be detected by lifting up on either the front or
+rear end of the crank-shaft and observing if there is any lost motion
+between the shaft journal and the main bearing caps. It is not necessary
+to take an engine entirely apart to examine the main bearings, as in
+most forms these may be readily reached by removing the sump. The
+symptoms of worn main bearings are not hard to identify. If an engine
+knocks regardless of speed or spark-lever position, and the trouble is
+not due to carbon deposits in the combustion chamber, one may reasonably
+surmise that the main bearings have become loose or that lost motion may
+exist at the connecting rod big ends, and possibly at the wrist pins.
+The main journals of any well resigned engine are usually proportioned
+with ample surface and will not wear unduly unless lubrication has been
+neglected. The connecting rod bearings wear quicker than the main
+bearings owing to being subjected to a greater unit stress, and it may
+be necessary to take these up.
+
+
+ADJUSTING MAIN BEARINGS
+
+[Illustration: Fig. 187.--Tools and Processes Used in Refitting Engine
+Bearings.]
+
+When the bearings are not worn enough to require refitting the lost
+motion can often be eliminated by removing one or more of the thin shims
+or liners ordinarily used to separate the bearing caps from the seat.
+These are shown at Fig. 187, A. Care must be taken that an even number
+of shims of the same thickness are removed from each side of the
+journal. If there is considerable lost motion after one or two shims
+have been removed, it will be advisable to take out more shims and to
+scrape the bearing to a fit before the bearing cap is tightened up. It
+may be necessary to clean up the crank-shaft journals as these may be
+scored due to not having received clean oil or having had bearings seize
+upon them. It is not difficult to true up the crank-pins or main
+journals if the score marks are not deep. A fine file and emery cloth
+may be used, or a lapping tool such as depicted at Fig. 187, B. The
+latter is preferable because the file and emery cloth will only tend to
+smooth the surface while the lap will have the effect of restoring the
+crank to proper contour.
+
+A lapping tool may be easily made, as shown at B, the blocks being of
+lead or hard wood. As the width of these are about half that of the
+crank-pin the tool may be worked from side to side as it is rotated. An
+abrasive paste composed of fine emery powder and oil is placed between
+the blocks, and the blocks are firmly clamped to the crank-pin. As the
+lead blocks bed down, the wing nut should be tightened to insure that
+the abrasive will be held with some degree of pressure against the
+shaft. A liberal supply of new abrading material is placed between the
+lapping blocks and crank-shaft from time to time and the old mixture
+cleaned off with gasoline. It is necessary to maintain a side to side
+movement of the lapping tool in order to have the process affect the
+whole width of the crank-pin equally. The lapping is continued until a
+smooth surface is obtained. If a crank-pin is worn out of true to any
+extent the only method of restoring it is to have it ground down to
+proper circular form by a competent mechanic having the necessary
+machine tools to carry on the work accurately. A crank-pin truing tool
+that may be worked by hand is shown at Fig. 187, K.
+
+After the crank-shaft is trued the next operation is to fit it to the
+main bearings or rather to scrape these members to fit the shaft
+journal. In order to bring the brasses closer together, it may be
+necessary to remove a little metal from the edges of the caps to
+compensate for the lost motion. A very simple way of doing this is shown
+at Fig. 187, D. A piece of medium emery cloth is rested on the surface
+plate and the box or brass is pushed back and forth over that member by
+hand, the amount of pressure and rapidity of movement being determined
+by the amount of metal it is necessary to remove. This is better than
+filing, because the edges will be flat and there will be no tendency
+for the bearing caps to rock when placed against the bearing seat. It is
+important to take enough off the edges of the boxes to insure that they
+will grip the crank tightly. The outer diameter must be checked with a
+pair of calipers during this operation to make sure that the surfaces
+remain parallel. Otherwise, the bearing brasses will only grip at one
+end and with such insufficient support they will quickly work loose,
+both in the bearing seat and bearing cap.
+
+
+SCRAPING BRASSES TO FIT
+
+To insure that the bearing brasses will be a good fit on the trued-up
+crank-pins or crank-shaft journals, they must be scraped to fit the
+various crank-shaft journals. The process of scraping, while a tedious
+one, is not difficult, requiring only patience and some degree of care
+to do a good job. The surface of the crank-pin is smeared with Prussian
+blue pigment which is spread evenly over the entire surface. The
+bearings are then clamped together in the usual manner with the proper
+bolts, and the crank-shaft revolved several times to indicate the high
+spots on the bearing cap. At the start of the process of scraping in,
+the bearing may seat only at a few points as shown at Fig. 187, G.
+Continued scraping will bring the bearing surface as indicated at H,
+which is a considerable improvement, while the process may be considered
+complete when the brass indicates a bearing all over as at I. The high
+spots are indicated by blue, as where the shaft does not bear on the
+bearing there is no color. The high spots are removed by means of a
+scraping tool of the form shown at Fig. 187, F, which is easily made
+from a worn-out file. These are forged to shape and ground hollow as
+indicated in the section, and are kept properly sharpened by frequent
+rubbing on an ordinary oil stone. To scrape properly, the edge of the
+scraper must be very keen. The straight and curved half-round scrapers,
+shown at M and N, are used for bearings. The three-cornered scraper,
+outlined at O, is also used on curved surfaces, and is of value in
+rounding off the sharp corners. The straight or curved half-round type
+works well on soft-bearing metals, such as babbitt, or white brass, but
+on yellow brass or bronze it cuts very slowly, and as soon as the edge
+becomes dull considerable pressure is needed to remove any metal, this
+calling for frequent sharpening.
+
+When correcting errors on flat or curved surfaces by hand-scraping, it
+is desirable, of course, to obtain an evenly spotted bearing with as
+little scraping as possible. When the part to be scraped is first
+applied to the surface-plate, or to a journal in the case of a bearing,
+three or four "high" spots may be indicated by the marking material. The
+time required to reduce these high spots and obtain a bearing that is
+distributed over the entire surface depends largely upon the way the
+scraping is started. If the first bearing marks indicate a decided rise
+in the surface, much time can be saved by scraping larger areas than are
+covered by the bearing marks; this is especially true of large shaft and
+engine bearings, etc. An experienced workman will not only remove the
+heavy marks, but also reduce a larger area; then, when the bearing is
+tested again, the marks will generally be distributed somewhat. If the
+heavy marks which usually appear at first are simply removed by light
+scraping, these "point bearings" are gradually enlarged, but a much
+longer time will be required to distribute them.
+
+The number of times the bearing must be applied to the journal for
+testing is important, especially when the box or bearing is large and
+not easily handled. The time required to distribute the bearing marks
+evenly depends largely upon one's judgment in "reading" these marks. In
+the early stages of the scraping operation, the marks should be used
+partly as a guide for showing the high areas, and instead of merely
+scraping the marked spot the surface surrounding it should also be
+reduced, unless it is evident that the unevenness is local. The idea
+should be to obtain first a few large but generally distributed marks;
+then an evenly and finely spotted surface can be produced quite easily.
+
+In fitting brasses when these are of the removable type, two methods may
+be used. The upper half of the engine base may be inverted on a suitable
+bench or stand and the boxes fitted by placing the crank-shaft in
+position, clamping down one bearing cap at a time and fitting each
+bearing in succession until they bed equally. From that time on the
+bearings should be fitted at the same time so the shaft will be parallel
+with the bottom of the cylinders. Considerable time and handling of the
+heavy crank-shaft may be saved if a preliminary fitting of the bearing
+brasses is made by clamping them together with a carpenter's wood clamp
+as shown at Fig. 187, J, and leaving the crank-shaft attached to the
+bench as shown at C. The brasses are revolved around the crank-shaft
+journal and are scraped to fit wherever high spots are indicated until
+they begin to seat fairly. When the brasses assume a finished appearance
+the final scraping should be carried on with all bearings in place and
+revolving the crank-shaft to determine the area of the seating. When the
+brasses are properly fitted they will not only show a full bearing
+surface, but the shaft will not turn unduly hard if revolved with a
+moderate amount of leverage.
+
+Bearings of white metal or babbitt can be fitted tighter than those of
+bronze, and care must be observed in supplying lubricant as considerably
+more than the usual amount is needed until the bearings are run in by
+several hours of test block work. Before the scraping process is started
+it is well to chisel an oil groove in the bearing as shown at Fig. 187,
+L. Grooves are very helpful in insuring uniform distribution of oil over
+the entire width of bearing and at the same time act as reservoirs to
+retain a supply of oil. The tool used is a round-nosed chisel, the
+effort being made to cut the grooves of uniform depth and having smooth
+sides. Care should be taken not to cut the grooves too deeply, as this
+will seriously reduce the strength of the bearing bushing. The shape of
+the groove ordinarily provided is clearly shown at Fig. 187, G, and it
+will be observed that the grooves do not extend clear to the edge of the
+bearing, but stop about a quarter of an inch from that point. The hole
+through which the oil is supplied to the bearing is usually drilled in
+such a way that it will communicate with the groove.
+
+The tool shown at Fig. 187, K, is of recent development, and is known as
+a "crank-shaft equalizer." This is a hand-operated turning tool,
+carrying cutters which are intended to smooth down scored crank-pins
+without using a lathe. The feed may be adjusted by suitable screws and
+the device may be fitted to crank-pins and shaft-journals of different
+diameters by other adjusting screws. This device is not hard to operate,
+being merely clamped around the crank-shaft in the same manner as the
+lapping tool previously described, and after it has been properly
+adjusted it is turned around by the levers provided for the purpose, the
+continuous rotary motion removing the metal just as a lathe tool would.
+
+
+FITTING CONNECTING RODS
+
+In the marine type rod, which is the form generally used in airplane
+engines, one or two bolts are employed at each side and the cap must be
+removed entirely before the bearing can be taken off of the crank-pin.
+The tightness of the brasses around the crank-pin can never be
+determined solely by the adjustment of the bolts, as while it is
+important that these should be drawn up as tightly as possible, the
+bearing should fit the shaft without undue binding, even if the brasses
+must be scraped to insure a proper fit. As is true of the main bearings,
+the marine form of connecting rod in some engines has a number of liners
+or shims interposed between the top and lower portions of the rod end,
+and these may be reduced in number when necessary to bring the brasses
+closer together. The general tendency in airplane engines is to
+eliminate shims in either the main or connecting rod bearings, and when
+wear is noticed the boxes or liners are removed and new ones supplied.
+The brasses are held in the connecting rod and cap by brass rivets and
+are generally attached in the main bearing by small brass machine
+screws. The form of box generally favored is a brass sand casting rich
+in copper to secure good heat conductivity which forms a backing for a
+thin layer of white brass, babbitt or similar anti-friction metal.
+
+[Illustration: Fig. 188.--Showing Points to Observe When Fitting
+Connecting Rod Brasses.]
+
+In fitting new brasses there are two conditions to be avoided, these
+being outlined at Fig. 188, B and C. In the case shown at C the light
+edges of the bushings are in contact, but the connecting rod and its cap
+do not meet. When the retaining nuts are tightened the entire strain is
+taken on the comparatively small area of the edges of the bushings which
+are not strong enough to withstand the strains existing and which
+flatten out quickly, permitting the bearing to run loose. In the example
+outlined at B the edges of the brasses do not touch when the connecting
+rod cap is drawn in place. This is not good practice, because the
+brasses soon become loose in their retaining member. In the case
+outlined it is necessary to file off the faces of the rod and cap until
+these meet, and to insure contact of the edges of the brasses as well.
+In event of the brasses coming together before the cap and rod make
+contact, as shown at C, the bearing halves should be reduced at the
+edges until both the caps and brasses meet against each other or the
+surfaces of the liners as shown at A.
+
+
+SPRUNG CAM-SHAFT
+
+If the cam-shaft is sprung or twisted it will alter the valve timing to
+such an extent that the smoothness of operation of the engine will be
+materially affected. If this condition is suspected the cam-shaft may be
+swung on lathe centers and turned to see if it runs out and can be
+straightened in any of the usual form of shaft-straightening machines.
+The shaft may be twisted without being sprung. This can only be
+determined by supporting one end of the shaft in an index head and the
+other end on a milling machine center. The cams are then checked to see
+that they are separated by the proper degree of angularity. This process
+is one that requires a thorough knowledge of the valve timing of the
+engine in question, and is best done at the factory where the engine was
+made. The timing gears should also be examined to see if the teeth are
+worn enough so that considerable back lash or lost motion exists between
+them. This is especially important where worm or spiral gears are used.
+A worn timing gear not only produces noise, but it will cause the time
+of opening and closing of the engine valves to vary materially.
+
+
+PRECAUTIONS IN REASSEMBLING PARTS
+
+When all of the essential components of a power plant have been
+carefully looked over and cleaned and all defects eliminated, either by
+adjustment or replacement of worn portions, the motor should be
+reassembled, taking care to have the parts occupy just the same
+relative positions they did before the motor was dismantled. As each
+part is added to the assemblage care should be taken to insure adequate
+lubrication of all new points of bearing by squirting liberal quantities
+of cylinder oil upon them with a hand oil can or syringe provided for
+the purpose. In adjusting the crank-shaft bearings, tighten them one at
+a time and revolve the shafts each time one of the bearing caps is set
+up to insure that the newly adjusted bearing does not have undue
+friction. All retaining keys and pins must be positively placed and it
+is good practice to cover such a part with lubricant before replacing it
+because it will not only drive in easier, but the part may be removed
+more easily if necessary at some future time. If not oiled, rust
+collects around it.
+
+When a piece is held by more than one bolt or screw, especially if it is
+a casting of brittle material such as cast iron or aluminum, the
+fastening bolts should be tightened uniformly. If one bolt is tightened
+more than the rest it is liable to spring the casting enough to break
+it. Spring washers, check nuts, split pins or other locking means should
+always be provided, especially on parts which are in motion or subjected
+to heavy loads.
+
+Before placing the cylinder over the piston it is imperative that the
+slots in the piston rings are spaced equidistant and that the piston is
+copiously oiled before the cylinder is slipped over it. When
+reassembling the inlet and exhaust manifolds it is well to use only
+perfect packings or gaskets and to avoid the use of those that seem to
+have hardened up or flattened out too much in service. If it is
+necessary to use new gaskets it is imperative to employ these at all
+joints on a manifold, because if old and new gaskets are used together
+the new ones are apt to keep the manifold from bedding properly upon the
+used ones. It is well to coat the threads of all bolts and screws
+subjected to heat, such as cylinder head and exhaust manifold retaining
+bolts, with a mixture of graphite and oil. Those that enter the water
+jacket should be covered with white or red lead or pipe thread
+compound. Gaskets will hold better if coated with shellac before the
+manifold or other parts are placed over them. The shellac fills any
+irregularities in the joint and assists materially in preventing leakage
+after the joint is made up and the coating has a chance to set.
+
+Before assembling on the shaft, it is necessary to fit the bearings by
+scraping, the same instructions given for restoring the contour of the
+main bearings applying just as well in this case. It is apparent that if
+the crank-pins are not round no amount of scraping will insure a true
+bearing. A point to observe is to make sure that the heads of the bolts
+are imbedded solidly in their proper position, and that they are not
+raised by any burrs or particles of dirt under the head which will
+flatten out after the engine has been run for a time and allow the bolts
+to slack off. Similarly, care should be taken that there is no foreign
+matter under the brasses and the box in which they seat. To guard
+against this the bolts should be struck with a hammer several times
+after they are tightened up, and the connecting rod can be hit sharply
+several times under the cap with a wooden mallet or lead hammer. It is
+important to pin the brasses in place to prevent movement, as
+lubrication may be interfered with if the bushing turns round and breaks
+the correct register between the oil hole in the cap and brasses.
+
+Care should be taken in screwing on the retaining nuts to insure that
+they will remain in place and not slack off. Spring washers should not
+be used on either connecting rod ends or main bearing nuts, because
+these sometimes snap in two pieces and leave the nut slack. The best
+method of locking is to use well-fitting split pins and castellated
+nuts.
+
+
+TESTING BEARING PARALLELISM
+
+It is not possible to give other than general directions regarding the
+proper degree of tightening for a connecting rod bearing, but as a guide
+to correct adjustment it may be said that if the connecting rod cap is
+tightened sufficiently so the connecting rod will just about fall over
+from a vertical position due to the piston weight when the bolts are
+fully tightened up, the adjustment will be nearly correct. As previously
+stated, babbitt or white metal bearings can be set up more tightly than
+bronze, as the metal is softer and any high spots will soon be leveled
+down with the running of the engine. It is important that care be taken
+to preserve parallelism of the wrist-pins and crank-shafts while
+scraping in bearings. This can be determined in two ways. That shown at
+Fig. 189, A, is used when the parts are not in the engine assembly and
+when the connecting rod bearing is being fitted to a mandrel or arbor
+the same size as the crank-pin. The arbor, which is finished very smooth
+and of uniform diameter, is placed in two V blocks, which in turn are
+supported by a level surface plate. An adjustable height gauge may be
+tried, first at one side of the wrist-pin which is placed at the upper
+end of the connecting rod, then at the other, and any variation will be
+easily determined by the degree of tilting of the rod. This test may be
+made with the wrist-pin alone, or if the piston is in place, a straight
+edge or spirit level may be employed. The spirit level will readily show
+any inclination while the straight edge is used in connection with the
+height gauge as indicated. Of course, the surface plate must be
+absolutely level when tests are made.
+
+When the connecting rods are being fitted with the crank-shaft in place
+in crank-case, and that member secured in the frame, a steel square may
+be used as it is reasonable to assume that the wrist-pin, and
+consequently the piston it carries, should observe a true relation with
+the top of the engine base. If the piston side is at right angles with
+the top of the engine base it is reasonable to assume that the wrist-pin
+and crank-pin are parallel. If the piston is canted to one side or the
+other, it will indicate that the brasses have been scraped tapering,
+which would mean considerable heating and undue friction if the piston
+is installed in the cylinder on account of the pressure against one
+portion of the cylinder wall. If the degree of canting is not too great,
+the connecting rods may be sprung very slightly to straighten up the
+piston, but this is a makeshift that is not advised. The height gauge
+method shown above may be used instead of the steel square, if desired,
+because the top of the crank-case is planed or milled true and should be
+parallel with the center line of the crank-shaft.
+
+[Illustration: Fig. 189.--Methods of Testing to Insure Parallelism of
+Bearings After Fitting.]
+
+
+CAM-SHAFTS AND TIMING GEARS
+
+Knocking sounds are also evident if the cam-shaft is loose in its
+bearings, and also if the cams or timing gears are loose on the shaft.
+The cam-shaft is usually supported by solid bearings of the removable
+bushing type, having no compensation for depreciation. If these bearings
+wear the only remedy is replacement with new ones. In the older makes of
+cars it was general practice to machine the cams separately and to
+secure these to the cam-shaft by means of taper pins or keys. These
+members sometimes loosened and caused noise. In the event of the cams
+being loose, care should be taken to use new keys or taper pins, as the
+case may be. If the fastening used was a pin, the hole through the
+cam-shaft will invariably be slightly oval from wear. In order to insure
+a tight job, the holes in cam and shaft must be reamed with the next
+larger size of standard taper reamer and a larger pin driven in. Another
+point to watch is the method of retaining the cam-shaft gear in place.
+On some engines the gear is fastened to a flange on the cam-shaft by
+retaining screws. These are not apt to become loose, but where reliance
+is placed on a key the cam-shaft gear may often be loose on its
+supporting member. The only remedy is to enlarge the key slot in both
+gear and shaft and to fit a larger retaining key.
+
+
+
+
+CHAPTER XII
+
+    Aviation Engine Types--Division in Classes--Anzani Engines--
+    Canton and Unne Engine--Construction of Gnome Engines--
+    "Monosoupape" Gnome--German "Gnome" Type--Le Rhone Engine--
+    Renault Air-Cooled Engine--Simplex Model "A" Hispano-Suiza--
+    Curtiss Aviation Motors--Thomas-Morse Model 88 Engine--
+    Duesenberg Engine--Aeromarine Six-Cylinder--Wisconsin Aviation
+    Engines--Hall-Scott Engines--Mercedes Motor--Benz Motor--
+    Austro-Daimler--Sunbeam-Coatalen.
+
+
+AVIATION ENGINE TYPES
+
+Inasmuch as numerous forms of airplane engines have been devised, it
+would require a volume of considerable size to describe even the most
+important developments of recent years. As considerable explanatory
+matter has been given in preceding chapters and the principles involved
+in internal combustion engine operation considered in detail, a
+relatively brief review of the features of some of the most successful
+airplane motors should suffice to give the reader a complete enough
+understanding of the art so all types of engines can be readily
+recognized and the advantages and disadvantages of each type understood,
+as well as defining the constructional features enough so the methods of
+locating and repairing the common engine and auxiliary system troubles
+will be fully grasped.
+
+Aviation engines can be divided into three main classes. One of the
+earliest attempts to devise distinctive power plant designs for aircraft
+involved the construction of engines utilizing a radial arrangement of
+the cylinders or a star-wise disposition. Among the engines of this
+class may be mentioned the Anzani, R. E. P. and the Salmson or Canton
+and Unne forms. The two former are air-cooled, the latter design is
+water-cooled. Engines of this type have been built in cylinder numbers
+ranging from three to twenty. While the simple forms were popular in the
+early days of aviation engine development, they have been succeeded by
+the more conventional arrangements which now form the largest class. The
+reason for the adoption of a star-wise arrangement of cylinders has been
+previously considered. Smoothness of running can only be obtained by
+using a considerable number of cylinders. The fundamental reason for the
+adoption of the star-wise disposition is that a better distribution of
+stress is obtained by having all of the pistons acting on the same
+crank-pin so that the crank-throw and pin are continuously under maximum
+stress. Some difficulty has been experienced in lubricating the lower
+cylinders in some forms of six cylinder, rotary crank, radial engines
+but these have been largely overcome so they are not as serious in
+practice as a theoretical consideration would indicate.
+
+Another class of engines developed to meet aviation requirements is a
+complete departure from the preceding class, though when the engines are
+at rest, it is difficult to differentiate between them. This class
+includes engines having a star-wise disposition of the cylinders but the
+cylinders themselves and the crank-case rotate and the crank-shaft
+remains stationary. The important rotary engines are the Gnome, the Le
+Rhone and the Clerget. By far the most important classification is that
+including engines which retain the approved design of the types of power
+plants that have been so widely utilized in automobiles and which have
+but slight modifications to increase reliability and mechanical strength
+and produce a reduction in weight. This class includes the vertical
+engines such as the Duesenberg and Hall-Scott four-cylinder; the
+Wisconsin, Aeromarine, Mercedes, Benz, and Hall-Scott six-cylinder
+vertical engines and the numerous eight- and twelve-cylinder Vee designs
+such as the Curtiss, Renault, Thomas-Morse, Sturtevant, Sunbeam, and
+others.
+
+
+ANZANI ENGINES
+
+The attention of the mechanical world was first directed to the great
+possibilities of mechanical flight when Bleriot crossed the English
+Channel in July, 1909, in a monoplane of his own design and
+construction, having the power furnished by a small three-cylinder
+air-cooled engine rated at about 24 horse-power and having cylinders
+4.13 inches bore and 5.12 inches stroke, stated to develop the power at
+about 1600 R.P.M. and weighing 145 pounds. The arrangement of this early
+Anzani engine is shown at Fig. 190, and it will be apparent that in the
+main, the lines worked out in motorcycle practice were followed to a
+large extent. The crank-case was of the usual vertically divided
+pattern, the cylinders and heads being cast in one piece and held to the
+crank-case by stud bolts passing through substantial flanges at the
+cylinder base. In order to utilize but a single crank-pin for the three
+cylinders it was necessary to use two forked rods and one rod of the
+conventional type. The arrangement shown at Fig. 190, called for the use
+of counter-balanced flywheels which were built up in connection with
+shafts and a crank-pin to form what corresponds to the usual crank-shaft
+assembly.
+
+[Illustration: Fig. 190.--Views Outlining Construction of Three-Cylinder
+Anzani Aviation Motor.]
+
+The inlet valves were of the automatic type so that a very simple valve
+mechanism consisting only of the exhaust valve push rods was provided.
+One of the difficulties of this arrangement of cylinders was that the
+impulses are not evenly spaced. For instance, in the forms where the
+cylinders were placed 60 degrees apart the space between the firing of
+the first cylinder and that next in order was 120 degrees crank-shaft
+rotation, after which there was an interval of 300 degrees before the
+last cylinder to fire delivered its power stroke. In order to increase
+the power given by the simple three-cylinder air-cooled engine a
+six-cylinder water-cooled type, as shown at Figs. 191 and 192, was
+devised. This was practically the same in action as the three-cylinder
+except that a double throw crank-shaft was used and while the
+explosions were not evenly spaced the number of explosions obtained
+resulted in fairly uniform application of power.
+
+[Illustration: Fig. 190a.--Illustrations Depicting Wrong and Right
+Methods of "Swinging the Stick" to Start Airplane Engine. At Top, Poor
+Position to Get Full Throw and Get Out of the Way. Below, Correct
+Position to Get Quick Turn Over of Crank-Shaft and Spring Away from
+Propeller.]
+
+[Illustration: Fig. 191.--The Anzani Six-Cylinder Water-Cooled Aviation
+Engine.]
+
+[Illustration: Fig. 192.--Sectional View of Anzani Six-Cylinder
+Water-Cooled Aviation Engine.]
+
+The latest design of three-cylinder Anzani engine, which is used to some
+extent for school machines, is shown at Fig. 193. In this, the
+three-cylinders are symmetrically arranged about the crank-case or 120
+degrees apart. The balance is greatly improved by this arrangement and
+the power strokes occur at equal intervals of 240 degrees of crank-shaft
+rotation. This method of construction is known as the Y design. By
+grouping two of these engines together, as outlined at Fig. 194, which
+gives an internal view, and at Fig. 195, which shows the sectional view,
+and using the ordinary form of double throw crank-shaft with crank-pins
+separated by 180 degrees, a six-cylinder radial engine is produced which
+runs very quietly and furnishes a steady output of power. The
+peculiarity of the construction of this engine is in the method of
+grouping the connecting rod about the common crank-pin without using
+forked rods or the "Mother rod" system employed in the Gnome engines. In
+the Anzani the method followed is to provide each connecting rod big end
+with a shoe which consists of a portion of a hollow cylinder held
+against the crank-pin by split clamping rings. The dimensions of these
+shoes are so proportioned that the two adjacent connecting rods of a
+group of three will not come into contact even when the connecting rods
+are at the minimum relative angle. The three shoes of each group rest
+upon a bronze sleeve which is in halves and which surrounds the
+crank-pin and rotates relatively to it once in each crank-shaft
+revolution. The collars, which are of tough bronze, resist the inertia
+forces while the direct pressure of the explosions is transmitted
+directly to the crank-pin bushing by the shoes at the big end of the
+connecting rod. The same method of construction, modified to some
+extent, is used in the Le Rhone rotary cylinder engine.
+
+[Illustration: Fig. 193.--Three-Cylinder Anzani Air-Cooled Y-Form
+Engine.]
+
+[Illustration: Fig. 194.--Anzani Fixed Crank-Case Engine of the
+Six-Cylinder Form Utilizes Air Cooling Successfully.]
+
+Both cylinders and pistons of the Anzani engines are of cast iron, the
+cylinders being provided with a liberal number of cooling flanges which
+are cast integrally. A series of auxiliary exhaust ports is drilled near
+the base of each cylinder so that a portion of the exhaust gases will
+flow out of the cylinder when the piston reaches the end of its power
+stroke. This reduces the temperature of the gases passing around the
+exhaust valves and prevents warping of these members. Another
+distinctive feature of this engine design is the method of attaching the
+Zenith carburetor to an annular chamber surrounding the rear portion of
+the crank-case from which the intake pipes leading to the intake valves
+radiate. The magneto is the usual six-cylinder form having the armature
+geared to revolve at one and one-half times crank-shaft speed.
+
+[Illustration: Fig. 195.--Sectional View Showing Internal Parts of
+Six-Cylinder Anzani Engine, with Starwise Disposition of Cylinders.]
+
+[Illustration: Fig. 196.--The Anzani Ten-Cylinder Aviation Engine at
+the Left, and the Twenty-Cylinder Fixed Type at the Right.]
+
+The Anzani aviation engines are also made in ten- and twenty-cylinder
+forms as shown at Fig. 196. It will be apparent that in the
+ten-cylinder form explosions will occur every 72 degrees of crank-shaft
+rotation, while in the twenty-cylinder, 200 horse-power engine at any
+instant five of the cylinders are always working and explosions are
+occurring every 36 degrees of crank-shaft rotation. On the
+twenty-cylinder engine, two carburetors are used and two magnetos,
+which are driven at two and one-half times crank-shaft speed. The
+general cylinder and valve construction is practically the same, as in
+the simpler engines.
+
+[Illustration: Fig. 197.--Application of R. E. P. Five-Cylinder
+Fan-Shape Air-Cooled Motor to Early Monoplane.]
+
+
+CANTON AND UNNE ENGINE
+
+This engine, which has been devised specially for aviation service, is
+generally known as the "Salmson" and is manufactured in both France and
+Great Britain. It is a nine-cylinder water-cooled radial engine, the
+nine cylinders being symmetrically disposed around the crank-shaft while
+the nine connecting rods all operate on a common crank-pin in somewhat
+the same manner as the rods in the Gnome motor. The crank-shaft of the
+Salmson engine is not a fixed one and inasmuch as the cylinders do not
+rotate about the crank-shaft it is necessary for that member to revolve
+as in the conventional engine. The stout hollow steel crank-shaft is in
+two pieces and has a single throw. The crank-shaft is built up somewhat
+the same as that of the Gnome engine. Ball bearings are used throughout
+this engine as will be evident by inspecting the sectional view given at
+Fig. 199. The nine steel connecting rods are machined all over and are
+fitted at each end with bronze bushings, the distance between the
+bearing centers being about 3.25 times crank length. The method of
+connecting up the rods to the crank-pin is one of the characteristic
+features of this design. No "mother" rod as supplied in the Gnome engine
+is used in this type inasmuch as the steel cage or connecting rod
+carrier is fitted with symmetrically disposed big end retaining pins.
+Inasmuch as the carrier is mounted on ball bearings some means must be
+provided of regulating the motion of the carrier as if no means were
+provided the resulting motion of the pistons would be irregular.
+
+[Illustration: Fig. 198.--The Canton and Unne Nine-Cylinder Water-Cooled
+Radial Engine.]
+
+The method by which the piston strokes are made to occur at precise
+intervals involves a somewhat lengthy and detailed technical
+explanation. It is sufficient to say that an epicyclic train of gears,
+one of which is rigidly attached to the crank-case so it cannot rotate
+is used, while other gears make a connection between the fixed gear and
+with another gear which is exactly the same size as the fixed gear
+attached to the crank-case and which is formed integrally with the
+connecting rod carrier. The action of the gearing is such that the cage
+carrying the big end retaining pins does not rotate independently of
+the crank-shaft, though, of course, the crank-shaft or rather crank-pin
+bearings must turn inside of the big end carrier cage.
+
+[Illustration: Fig. 199.--Sectional View Showing Construction of Canton
+and Unne Water-Cooled Radial Cylinder Engine.]
+
+Cylinders of this engine are of nickel steel machined all over and carry
+water-jackets of spun copper which are attached to the cylinders by
+brazing. The water jackets are corrugated to permit the cylinder to
+expand freely. The ignition is similar to that of the fixed crank
+rotating cylinder engine. An ordinary magneto of the two spark type
+driven at 1-3/4 times crank-shaft speed is sufficient to ignite the
+seven-cylinder form, while in the nine-cylinder engines the ignition
+magneto is of the "shield" type giving four sparks per revolution. The
+magneto is driven at 1-1/9 times crank-shaft speed. Nickel steel valves
+are used and are carried in castings or cages which screw into bosses in
+the cylinder head. Each valve is cam operated through a tappet, push rod
+and rocker arm, seven cams being used on a seven-cylinder engine and
+nine cams on the nine-cylinder. One cam serves to open both valves as in
+its rotation it lifts the tappets in succession and so operates the
+exhaust and inlet valves respectively. This method of operation involves
+the same period of intake and exhaust. In normal engine practice the
+inlet valve opens 12 degrees late and closes 20 degrees late. The
+exhaust opens 45 degrees early and closes 6 degrees late. This means
+about 188 degrees in the case of inlet valve and 231 degrees crank-shaft
+travel for exhaust valves. In the Salmson engine, the exhaust closes and
+the inlet opens at the outer dead center and the exhaust opens and the
+inlet closes at about the inner dead center. This engine is also made in
+a fourteen-cylinder 200 B. H. P. design which is composed of two groups
+of seven-cylinders, and it has been made in an eighteen-cylinder design
+of 600 horse-power. The nine-cylinder 130 horse-power has a cylinder
+bore of 4.73 inches and a stroke of 5.52 inches. Its normal speed of
+rotation is 1250 R. P. M. Owing to the radial arrangement of the
+cylinders, the weight is but 4-1/4 pounds per B. H. P.
+
+
+CONSTRUCTION OF EARLY GNOME MOTOR
+
+It cannot be denied that for a time one of the most widely used of
+aeroplane motors was the seven-cylinder revolving air-cooled Gnome, made
+in France. For a total weight of 167 pounds this motor developed 45 to
+47 horse-power at 1,000 revolutions, being equal to 3.35 pounds per
+horse-power, and has proved its reliability by securing many
+long-distance and endurance records. The same engineers have produced
+a nine-cylinder and by combining two single engines a fourteen-cylinder
+revolving Gnome, having a nominal rating of 100 horse-power, with which
+world's speed records were broken. A still more powerful engine has been
+made with eighteen-cylinders. The nine-cylinder "monosoupape" delivers
+100 horse-power at 1200 R. P. M., the engine of double that number of
+cylinders is rated at about 180 horse-power.
+
+[Illustration: Fig. 200.--Sectional View Outlining Construction of Early
+Type Gnome Valve-in-Piston Type Motor.]
+
+Except in the number of cylinders and a few mechanical details the
+fourteen-cylinder motor is identical with the seven-cylinder one; fully
+three-quarters of the parts used by the assemblers would do just as well
+for one motor as for the other. Owing to the greater power demands of
+the modern airplane the smaller sizes of Gnome engines are not used as
+much as they were except for school machines. There is very little in
+this motor that is common to the standard type of vertical motorcar
+engine. The cylinders are mounted radially round a circular crank-case;
+the crank-shaft is fixed, and the entire mass of cylinders and
+crank-case revolves around it as outlined at Fig. 200. The explosive
+mixture and the lubricating oil are admitted through the fixed hollow
+crank-shaft, passed into the explosion chamber through an automatic
+intake valve in the piston head in the early pattern, and the spent
+gases exhausted through a mechanically operated valve in the cylinder
+head. The course of the gases is practically a radial one. A peculiarity
+of the construction of the motor is that nickel steel is used
+throughout. Aluminum is employed for the two oil pump housings; the
+single compression ring known as the "obdurator" for each piston is made
+of brass; there are three or four brass bushes; gun metal is employed
+for certain pins--the rest is machined out of chrome nickel steel. The
+crank-case is practically a steel hoop, the depth depending on whether
+it has to receive seven-or fourteen-cylinders; it has seven or fourteen
+holes bored as illustrated on its circumference. When fourteen or
+eighteen cylinders are used the holes are bored in two distinct planes,
+and offset in relation one to the other.
+
+The cylinders of the small engine which have a bore of 4-3/10 inches and
+a stroke of 4-7/10 inches, are machined out of the solid bar of steel
+until the thickness of the walls is only 1.5 millimeters--.05905 inch,
+or practically 1/16 inch. Each one has twenty-two fins which gradually
+taper down as the region of greatest pressure is departed from. In
+addition to carrying away heat, the fins assist in strengthening the
+walls of the cylinder. The barrel of the cylinder is slipped into the
+hole bored for it on the circumference of the crank-case and secured by
+a locking member in the nature of a stout compression ring, sprung onto
+a groove on the base of the cylinder within the crank chamber. On each
+lateral face of the crank chamber are seven holes, drilled right through
+the chamber parallel with the crank-shaft. Each one of these holes
+receives a stout locking-pin of such a diameter that it presses against
+the split rings of two adjacent cylinders; in addition each cylinder is
+fitted with a key-way. This construction is not always followed, some of
+the early Gnome engines using the same system of cylinder retention as
+used on the latest "monosoupape" pattern.
+
+The exhaust valve is mounted in the cylinder head, Fig. 201, its seating
+being screwed in by means of a special box spanner. On the
+fourteen-cylinder model the valve is operated directly by an overhead
+rocker arm with a gun metal rocker at its extremity coming in contact
+with the extremity of the valve stem. As in standard motor car practice,
+the valve is opened under the lift of the vertical push rod, actuated by
+the cam. The distinctive feature is the use of a four-blade leaf spring
+with a forked end encircling the valve stems and pressing against a
+collar on its extremity. On the seven-cylinder model the movement is
+reversed, the valve being opened on the downward pull of the push rod,
+this lifting the outer extremity of the main rocker arm, which tips a
+secondary and smaller rocker arm in direct contact with the extremity
+of the valve stem. The springs are the same in each case. The two types
+are compared at A and B, Fig. 202.
+
+[Illustration: Fig. 201.--Sectional View of Early Type Gnome Cylinder
+and Piston Showing Construction and Application of Inlet and Exhaust
+Valves.]
+
+The pistons, like the cylinders, are machined out of the solid bar of
+nickel steel, and have a portion of their wall cut away, so that the two
+adjacent ones will not come together at the extremity of their stroke.
+The head of the piston is slightly reduced in diameter and is provided
+with a groove into which is fitted a very light L-section brass split
+ring; back of this ring and carried within the groove is sprung a light
+steel compression ring, serving to keep the brass ring in expansion. As
+already mentioned, the intake valves are automatic, and are mounted in
+the head of the piston as outlined at Fig. 202, C. The valve seating is
+in halves, the lower portion being made to receive the wrist-pin and
+connecting rod, and the upper portion, carrying the valve, being screwed
+into it. The spring is composed of four flat blades, with the hollowed
+stem of the automatic valve passing through their center and their two
+extremities attached to small levers calculated to give balance against
+centrifugal force. The springs are naturally within the piston, and are
+lubricated by splash from the crank chamber. They are of a delicate
+construction, for it is necessary that they shall be accurately balanced
+so as to have no tendency to fly open under the action of centrifugal
+force. The intake valve is withdrawn by the use of special tools through
+the cylinder head, the exhaust valve being first dismounted.
+
+[Illustration: Fig. 202.--Details of Old Style Gnome Motor Inlet and
+Exhaust Valve Construction and Operation.]
+
+The fourteen-cylinder motor shown at Fig. 203, has a two-throw
+crank-shaft with the throws placed at 180 degrees, each one receiving
+seven connecting rods. The parts are the same as for the seven-cylinder
+motor, the larger one consisting of two groups placed side by side. For
+each group of seven-cylinders there is one main connecting rod, together
+with six auxiliary rods. The main connecting rod, which, like the
+others, is of H section, has machined with it two L-section rings bored
+with six holes--51-1/2 degrees apart to take the six other connecting
+rods. The cage of the main connecting rod carries two ball races, one on
+either side, fitting onto the crank-pin and receiving the thrust of the
+seven connecting rods. The auxiliary connecting rods are secured in
+position in each case by a hollow steel pin passing through the two
+rings. It is evident that there is a slightly greater angularity for the
+six shorter rods, known as auxiliary connecting rods, than for the
+longer main rods; this does not appear to have any influence on the
+running of the motor.
+
+[Illustration: Fig. 203.--The Gnome Fourteen-Cylinder 100 Horse-Power
+Aviation Engine.]
+
+Coming to the manner in which the earliest design exhaust valves are
+operated on the old style motor, this at first sight appears to be one
+of the most complicated parts of the motor, probably because it is one
+in which standard practice is most widely departed from. Within the
+cylindrical casing bolted to the rear face of the crank-case are seven,
+thin flat-faced steel rings, forming female cams. Across a diameter of
+each ring is a pair of projecting rods fitting in brass guides and
+having their extremities terminating in a knuckle eye receiving the
+adjustable push rods operating the overhead rocker arms of the exhaust
+valve. The guides are not all in the same plane, the difference being
+equal to the thickness of the steel rings, the total thickness being
+practically 2 inches. Within the female cams is a group of seven male
+cams of the same total thickness as the former and rotating within them.
+As the boss of the male cam comes into contact with the flattened
+portion of the ring forming the female cam, the arm is pushed outward
+and the exhaust valve opened through the medium of the push-rod and
+overhead rocker. This construction was afterwards changed to seven male
+cams and simple valve operating plunger and roller cam followers as
+shown at Fig. 204.
+
+On the face of the crank-case of the fourteen-cylinder motor opposite to
+the valve mechanism is a bolted-on end plate, carrying a pinion for
+driving the two magnetos and the two oil pumps, and having bolted to it
+the distributor for the high-tension current. Each group of
+seven-cylinders has its own magneto and lubricating pump. The two
+magnetos and the two pumps are mounted on the fixed platform carrying
+the stationary crank-shaft, being driven by the pinion on the revolving
+crank chamber. The magnetos are geared up in the proportion of 4 to 7.
+Mounted on the end plate back of the driving pinion are the two
+high-tension distributor plates, each one with seven brass segments let
+into it and connection made to the plugs by means of plain brass wire.
+The wire passes through a hole in the plug and is then wrapped round
+itself, giving a loose connection.
+
+[Illustration: Fig. 204.--Cam and Cam-Gear Case of the Gnome
+Seven-Cylinder Revolving Engine.]
+
+[Illustration: Fig. 205.--Diagrams Showing Why An Odd Number of
+Cylinders is Best for Rotary Cylinder Motors.]
+
+A good many people doubtless wonder why rotary engines are usually
+provided with an odd number of cylinders in preference to an even
+number. It is a matter of even torque, as can easily be understood from
+the accompanying diagram. Fig. 205, A, represents a six-cylinder rotary
+engine, the radial lines indicating the cylinders. It is possible to
+fire the charges in two ways, firstly, in rotation, 1, 2, 3, 4, 5, 6,
+thus having six impulses in one revolution and none in the next; or
+alternately, 1, 3, 5, 2, 4, 6, in which case the engine will have turned
+through an equal number of degrees between impulses 1 and 3, and 3 and
+5, but a greater number between 5 and 2, even again between 2 and 4, 4
+and 6, and a less number between 6 and 1, as will be clearly seen on
+reference to the diagram. Turning to Fig. 205, B, which represents a
+seven-cylinder engine. If the cylinders fire alternately it is obvious
+that the engine turns through an equal number of degrees between each
+impulse, thus, 1, 3, 5, 7, 2, 4, 6, 1, 3, etc. Thus supposing the engine
+to be revolving, the explosion takes place as each alternate cylinder
+passes, for instance, the point 1 on the diagram, and the ignition is
+actually operated in this way by a single contact.
+
+[Illustration: Fig. 206.--Simple Carburetor Used On Early Gnome Engines
+Attached to Fixed Crank-Shaft End.]
+
+The crank-shaft of the Gnome, as already explained, is fixed and hollow.
+For the seven- and nine-cylinder motors it has a single throw, and for
+the fourteen- and eighteen-cylinder models has two throws at 180
+degrees. It is of the built-up type, this being necessary on account of
+the distinctive mounting of the connecting rods. The carburetor shown at
+Fig. 206 is mounted at one end of the stationary crank-shaft, and the
+mixture is drawn in through a valve in the piston as already explained.
+There is neither float chamber nor jet. In many of the tests made at the
+factory it is said the motor will run with the extremity of the gasoline
+pipe pushed into the hollow crank-shaft, speed being regulated entirely
+by increasing or decreasing the flow through the shut-off valve in the
+base of the tank. Even under these conditions the motor has been
+throttled down to run at 350 revolutions without misfiring. Its normal
+speed is 1,000 to 1,200 revolutions a minute. Castor oil is used for
+lubricating the engine, the oil being injected into the hollow
+crank-shaft through slight-feed fittings by a mechanically operated pump
+which is clearly shown in sectional diagrams at Fig. 207.
+
+[Illustration: Fig. 207.--Sectional Views of the Gnome Oil Pump.]
+
+The Gnome is a considerable consumer of lubricant, the makers' estimate
+being 7 pints an hour for the 100 horse-power motor; but in practice
+this is largely exceeded. The gasoline consumption is given as 300 to
+350 grammes per horse-power. The total weight of the fourteen-cylinder
+motor is 220 pounds without fuel or lubricating oil. Its full power is
+developed at 1,200 revolutions, and at this speed about 9 horse-power is
+lost in overcoming air resistance to cylinder rotation.
+
+[Illustration: Fig. 208.--Simplified Diagram Showing Gnome Motor Magneto
+Ignition System.]
+
+While the Gnome engine has many advantages, on the other hand, the head
+resistance offered by a motor of this type is considerable; there is a
+large waste of lubricating oil due to the centrifugal force which tends
+to throw the oil away from the cylinders; the gyroscopic effect of the
+rotary motor is detrimental to the best working of the aeroplane, and
+moreover it requires about seven per cent. of the total power developed
+by the motor to drive the revolving cylinders around the shaft. Of
+necessity, the compression of this type of motor is rather low, and an
+additional disadvantage manifests itself in the fact that there is as
+yet no satisfactory way of muffling the rotary type of motor.
+
+
+GNOME "MONOSOUPAPE" TYPE
+
+The latest type of Gnome engine is known as the "monosoupape" type
+because but one valve is used in the cylinder head, the inlet valve in
+the piston being dispensed with on account of the trouble caused by that
+member on earlier engines. The construction of this latest type follows
+the lines established in the earlier designs to some extent and it
+differs only in the method of charging. The very rich mixture of gas and
+air is forced into the crank-case through the jet inside the
+crank-shaft, and enters the cylinder when the piston is at its lowest
+position, through the half-round openings in the guiding flange and the
+small holes or ports machined in the cylinder and clearly shown at Fig.
+210. The returning piston covers the port, and the gas is compressed and
+fired in the usual way. The exhaust is through a large single valve in
+the cylinder head, which gives rise to the name "monosoupape," or
+single-valve motor, and this valve also remains open a portion of the
+intake stroke to admit air into the cylinder and dilute the rich gas
+forced in from the crank-case interior. Aviators who have used the early
+form of Gnome say that the inlet valve in the piston type was prone to
+catch on fire if any valve defect materialized, but the "monosoupape"
+pattern is said to be nearly free of this danger. The bore of the 100
+horse-power nine-cylinder engine is 110 mm., the piston stroke 150 mm.
+Extremely careful machine work and fitting is necessary. In many parts,
+tolerances of less than .0004" (four ten thousandths of an inch) are all
+that are allowed. This is about one-sixth the thickness of the average
+human hair, and in other parts the size must be absolutely standard, no
+appreciable variation being allowable. The manufacture of this engine
+establishes new mechanical standards of engine production in this
+country. Much machine work is needed in producing the finished
+components from the bar and forging.
+
+[Illustration: Fig. 209.--The G. V. Gnome "Monosoupape" Nine-Cylinder
+Rotary Engine Mounted on Testing Stand.]
+
+[Illustration: Fig. 210.--Sectional View Showing Construction of General
+Vehicle Co. "Monosoupape" Gnome Engine.]
+
+The cylinders, for example, are machined from 6 inch solid steel bars,
+which are sawed into blanks 11 inches in length and weighing about 97
+pounds. The first operation is to drill a 2-1/16 inch hole through the
+center of the block. A heavy-duty drilling machine performs this work,
+then the block goes to the lathe for further operations. Fig. 211 shows
+six stages of the progress of a cylinder, a few of the intermediate
+steps being omitted. These give, however, a good idea of the work done.
+The turning of the gills, or cooling flanges, is a difficult
+proposition, owing to the depth of the cut and the thin metal that forms
+the gills. This operation requires the utmost care of tools and the use
+of a good lubricant to prevent the metal from tearing as the tools
+approach their full depth. These gills are only 0.6 mm., or 0.0237 in.,
+thick at the top, tapering to a thickness of 1.4 mm. (0.0553 in.) at the
+base, and are 16 mm. (0.632 in.) deep. When the machine work is
+completed the cylinder weighs but 5-1/2 pounds.
+
+[Illustration: Fig. 211.--How a Gnome Cylinder is Reduced from Solid
+Chunk of Steel Weighing 97 Pounds to Finished Cylinder Weighing 5-1/2
+Pounds.]
+
+
+GNOME FUEL SYSTEM, IGNITION AND LUBRICATION
+
+The following description of the fuel supply, ignition and oiling of the
+"monosoupape," or single valve Gnome, is taken from "The Automobile."
+
+Gasoline is fed to the engine by means of air pressure at 5 pounds per
+sq. in., which is produced by the air pump on the engine clearly shown
+at Fig. 210. A pressure gauge convenient to the operator indicates this
+pressure, and a valve enables the operator to control it. No carburetor
+is used. The gasoline flows from the tank through a shut-off valve near
+the operator and through a tube leading through the hollow crank-shaft
+to a spray nozzle located in the crank-case. There is no throttle valve,
+and as each cylinder always receives the same amount of air as long as
+the atmospheric pressure is the same, the output cannot be varied by
+reducing the fuel supply, except within narrow limits. A fuel capacity
+of 65 gallons is provided. The fuel consumption is at the rate of 12 U.
+S. gallons per hour.
+
+The high-tension magnetos, with double cam or two break per revolution
+interrupter, is located on the thrust plate in an inverted position, and
+is driven at such a speed as to produce nine sparks for every two
+revolutions; that is, at 2-1/4 times engine speed. A Splitdorf magneto
+is fitted. There is no distributor on the magneto. The high-tension
+collector brush of the magneto is connected to a distributor brush
+holder carried in the bearer plate of the engine. The brush in this
+brush holder is pressed against a distributor ring of insulating
+material molded in position in the web of a gear wheel keyed to the
+thrust plate, which gear serves also for starting the engine by hand.
+Molded in this ring of insulating material are nine brass contact
+sectors, connecting with contact screws at the back side of the gear,
+from which bare wires connect to the spark-plugs. The distributor
+revolves at engine speed, instead of at half engine speed as on ordinary
+engines, and the distributor brush is brought into electrical connection
+with each spark-plug every time the piston in the cylinder in which this
+spark-plug is located approaches the outer dead center. However, on the
+exhaust stroke no spark is being generated in the magneto, hence none is
+produced at the spark-plug.
+
+[Illustration: Fig. 212.--The Gnome Engine Cam-Gear Case, a Fine Example
+of Accurate Machine Work.]
+
+Ordinarily the engine is started by turning on the propeller, but for
+emergency purposes as in seaplanes or for a quick "get away" if landing
+inadvertently in enemy territory, a hand starting crank is provided.
+This is supported in bearings secured to the pressed steel carriers of
+the engine and is provided with a universal joint between the two
+supports so as to prevent binding of the crank in the bearings due to
+possible distortion of the supports. The gear on this starting crank and
+the one on the thrust plate with which it meshes are cut with helical
+teeth of such hand that the starting pinion is thrown out of mesh as
+soon as the engine picks up its cycle. A coiled spring surrounds part of
+the shaft of the starting crank and holds it out of gear when not in
+use.
+
+[Illustration: Fig. 213.--G. V. Gnome "Monosoupape," with Cam-Case Cover
+Removed to Show Cams and Valve-Operating Plungers with Roller Cam
+Followers.]
+
+Lubricating oil is carried in a tank of 25 gallon capacity, and if this
+tank has to be placed in a low position it is connected with the
+air-pressure line, so that the suction of the oil pump is not depended
+upon to get the oil to the pump. From the bottom of the oil tank a pipe
+leads to the pump inlet. There are two outlets from the pump, each
+entering the hollow crank-shaft, and there is a branch from each outlet
+pipe to a circulation indicator convenient to the operator. One of the
+oil leads feeds to the housing in the thrust plate containing the two
+rear ball bearings, and the other lead feeds through the crank-pin to
+the cams, as already explained.
+
+Owing to the effect of centrifugal force and the fact that the oil is
+not used over again, the oil consumption of a revolving cylinder engine
+is considerably higher than that of a stationary cylinder engine. Fuel
+consumption is also somewhat higher, and for this reason the revolving
+cylinder engine is not so well suited for types of airplanes designed
+for long trips, as the increased weight of supplies required for such
+trips, as compared with stationary cylinder type motors, more than
+offsets the high weight efficiency of the engine itself. But for short
+trips, and especially where high speed is required, as in single seated
+scout and battle planes or "avions de chasse," as the French say, the
+revolving cylinder engine has the advantage. The oil consumption of the
+Gnome engine is as high as 2.4 gallon per hour. Castor oil is used for
+lubrication because it is not cut by the gasoline mist present in the
+engine interior as an oil of mineral derivation would be.
+
+
+GERMAN "GNOME" TYPE ENGINE
+
+[Illustration: Fig. 214.--The 50 Horse-Power Rotary Bayerischen Motoren
+Gesellschaft Engine, a German Adaptation of the Early Gnome Design.]
+
+A German adaptation of the Gnome design is shown at Fig. 214. This is
+known as the Bayerischen Motoren Gesellschaft engine and the type shown
+is an early design rated at 50 horse-power. The bore is 110 mm., the
+stroke is 120 mm., and it is designed to run at a speed of 1,200 R. P.
+M. It is somewhat similar in design to the early Gnome "valve-in-piston"
+design except that two valves are carried in the piston top instead of
+one. The valve operating arrangement is different also, as a single four
+point cam is used to operate the seven exhaust valves. It is driven by
+epicyclic gearing, the cam being driven by an internal gear machined
+integrally with it, the cam being turned at 7/8 times the engine speed.
+Another feature is the method of holding the cylinders on the
+crank-case. The cylinder is provided with a flange that registers with a
+corresponding member of the same diameter on the crank-case. A U
+section, split clamping ring is bolted in place as shown, this holding
+both flanges firmly together and keeping the cylinder firmly seated
+against the crank-case flange. The "monosoupape" type has also been
+copied and has received some application in Germany, but the most
+successful German airplanes are powered with six-cylinder vertical
+engines such as the Benz and Mercedes.
+
+
+THE LE RHONE MOTOR
+
+The Le Rhone motor is a radial revolving cylinder engine that has many
+of the principles which are incorporated in the Gnome but which are
+considered to be an improvement by many foreign aviators. Instead of
+having but one valve in the cylinder head, as the latest type
+"monosoupape" Gnome has, the Le Rhone has two valves, one for intake and
+one for exhaust in each cylinder. By an ingenious rocker arm and tappet
+rod arrangement it is possible to operate both valves with a single push
+rod. Inlet pipes communicate with the crank-case at one end and direct
+the fresh gas to the inlet valve cage at the other. Another peculiarity
+in the design is the method of holding the cylinders in place. Instead
+of having a vertically divided crank-case as the Gnome engine has and
+clamping both halves of the case around the cylinders, the crank-case of
+the Le Rhone engine is in the form of a cylinder having nine bosses
+provided with threaded openings into which the cylinders are screwed. A
+thread is provided at the base of each cylinder and when the cylinder
+has been screwed down the proper amount it is prevented from further
+rotation about its own axis by a substantial lock nut which screws down
+against the threaded boss on the crank-case. The external appearance of
+the Le Rhone type motor is clearly shown at Fig. 215, while the general
+features of construction are clearly outlined in the sectional views
+given at Figs. 216 and 217.
+
+[Illustration: Fig. 215--Nine-Cylinder Revolving Le Rhone Type Aviation
+Engine.]
+
+[Illustration: Fig. 216.--Part Sectional Views of Le Rhone Rotary
+Cylinder Engine, Showing Method of Cylinder Retention, Valve Operation
+and Novel Crank Disc Assembly.]
+
+[Illustration: Fig. 217.--Side Sectional View of Le Rhone Aviation
+Engine.]
+
+[Illustration: Fig. 218.--View Showing Le Rhone Valve Action and
+Connecting Rod Big End Arrangement.]
+
+The two main peculiarities of this motor are the method of valve
+actuation by two large cams and the distinctive crank-shaft and
+connecting rod big end construction. The connecting rods are provided
+with "feet" or shoes on the end which fit into grooves lined with
+bearing metal which are machined into crank discs revolving on ball
+bearings and which are held together so that the connecting rod big ends
+are sandwiched between them by clamping screws. This construction is a
+modification of that used on the Anzani six-cylinder radial engine.
+There are three grooves machined in each crank disc and three connecting
+rod big ends run in each pair of grooves. The details of this
+construction can be readily ascertained by reference to explanatory
+diagrams at Figs. 218 and 219, A. Three of the rods which work in the
+groove nearest the crank-pin are provided with short shoes as shown at
+Fig. 219, B. The short shoes are used on the rods employed in cylinders
+number 1, 4, and 7. The set of connecting rods that work in the central
+grooves are provided with medium-length shoes and actuate the pistons in
+cylinders numbers 3, 6, and 9. The three rods that work in the outside
+grooves have still longer shoes and are employed in cylinders numbers 2,
+5, and 8. The peculiar profile of the inlet and exhaust cam plates are
+shown at C, Fig. 219, while the construction of the wrist-pin, wrist-pin
+bushing and piston are clearly outlined at the sectional view at E. The
+method of valve actuation is clearly outlined at Fig. 220, which shows
+an end section through the cam case and also a partial side elevation
+showing one of the valve operating levers which is fulcrumed at a
+central point and which has a roller at one end bearing on one cam while
+the roller or cam follower at the other end bears on the other cam. The
+valve rocker arm actuating rod is, of course, operated by this simple
+lever and is attached to it in such a way that it can be pulled down to
+depress the inlet valve and pushed up to open the exhaust valve.
+
+[Illustration: Fig. 219.--Diagrams Showing Important Components of Le
+Rhone Motor.]
+
+[Illustration: Fig. 220.--How the Cams of the Le Rhone Motor Can Operate
+Two Valves with a Single Push Rod.]
+
+A carburetor of peculiar construction is employed in the Le Rhone
+engine, this being a very simple type as outlined at Fig. 221. It is
+attached to the threaded end of the hollow crank-shaft by a right and
+left coupling. The fuel is pumped to the spray nozzle, the opening in
+which is controlled by a fuel regulating needle having a long taper
+which is lifted out of the jet opening when the air-regulating slide is
+moved. The amount of fuel supplied the carburetor is controlled by a
+special needle valve fitting which combines a filter screen and which is
+shown at B. In regulating the speed of the Le Rhone engine, there are
+two possible means of controlling the mixture, one by altering the
+position of the air-regulating slide, which also works the metering
+needle in the jet, and the other by controlling the amount of fuel
+supplied to the spray nozzle through the special fitting provided for
+that purpose.
+
+[Illustration: Fig. 221.--The Le Rhone Carburetor at A and Fuel Supply
+Regulating Device at B.]
+
+In considering the action of this engine one can refer to Fig. 222. The
+crank O. M. is fixed, while the cylinders can turn about the crank-shaft
+center O and the piston turns around the crank-pin M, because of the
+eccentricity of the centers of rotation the piston will reciprocate in
+the cylinders. This distance is at its maximum when the cylinder is
+above O and at a minimum when it is above M, and the difference between
+these two positions is equal to the stroke, which is twice the distance
+of the crank-throw O, M. The explosion pressure resolves itself into the
+force F exerted along the line of the connecting rod A, M, and also into
+a force N, which tends to make the cylinders rotate around point O in
+the direction of the arrow. An odd number of cylinders acting on one
+crank-pin is desirable to secure equally spaced explosions, as the basic
+action is the same as the Gnome engine.
+
+[Illustration: Fig. 222.--Diagrams Showing Le Rhone Motor Action and
+Firing Order.]
+
+The magneto is driven by a gear having 36 teeth attached to crank-case
+which meshes with 16-tooth pinion on armature. The magneto turns at 2.25
+times crank-case speed. Two cams, one for inlet, one for exhaust, are
+mounted on a carrying member and act on nine rocker arms which are
+capable of giving a push-and-pull motion to the valve-actuating
+rocker-operating rods. A gear driven by the crank-case meshes with a
+larger member having internal teeth carried by the cam carrier. Each cam
+has five profiles and is mounted in staggered relation to the other.
+These give the nine fulcrumed levers the proper motion to open the inlet
+and exhaust valves at the proper time. The cams are driven at 45/50 or
+9/10 of the motor speed. The cylinder dimensions and timing follows; the
+weight can be approximated by figuring 3 pounds per horse-power.
+
+   80 H.P.     105 M/M bore       4.20" bore.
+               140 M/M stroke     5.60" stroke.
+
+  110 H.P.     112 M/M bore       4.48" bore.
+               170 M/M stroke     6.80" stroke.
+
+  Timing--Intake valve opening, lag    18 deg.}          18 deg.}
+          Intake valve closing, lag    35 deg.}          35 deg.}
+          Exhaust valve opening, lead  55 deg.} 110 H.P. 45 deg.} 80 H.P.
+          Exhaust valve closing, lag    5 deg.}           5 deg.}
+          Ignition time advance        26 deg.}          26 deg.}
+
+[Illustration: Fig. 223.--Diagram Showing Positions of Piston in Le
+Rhone Rotary Cylinder Motor.]
+
+
+THE RENAULT AIR-COOLED VEE ENGINE
+
+[Illustration: Fig. 224.--Diagrams Showing Valve Timing of Le Rhone
+Aviation Engine.]
+
+[Illustration: Fig. 225.--Diagrams Showing How Cylinder Cooling is
+Effected in Renault Vee Engines.]
+
+Air-cooled stationary engines are rarely used in airplanes, but the
+Renault Freres of France have for several years manufactured a complete
+series of such engines of the general design shown at Fig. 225, ranging
+from a low-powered one developed eight or nine years ago and rated at
+40 and 50 horse-power, to later eight-cylinder models rated at 70
+horse-power and a twelve-cylinder, or twin six, rated at 90 horse-power.
+The cylinders are of cast iron and are furnished with numerous cooling
+ribs which are cast integrally. The cylinder heads are separate
+castings and are attached to the cylinder as in early motorcycle engine
+practice, and serve to hold the cylinder in place on the aluminum alloy
+crank-case by a cruciform yoke and four long hold-down bolts (Fig. 226).
+The pistons are of cast steel and utilize piston rings of cast iron. The
+valves are situated on the inner side of the cylinder head, the
+arrangement being unconventional in that the exhaust valves are placed
+above the inlet. The inlet valves seat in an extension of the combustion
+head and are actuated by direct push rod and cam in the usual manner
+while an overhead gear in which rockers are operated by push rods is
+needed to actuate the exhaust valves. The valve action is clearly shown
+in Figs. 226 and 227. The air stream by which the cylinders are cooled
+is produced by a centrifugal or blower type fan of relatively large
+diameter which is mounted on the end of a crank-shaft and the air blast
+is delivered from this blower into an enclosed space between the
+cylinder from which it escapes only after passing over the cooling fins.
+In spite of the fact that considerable prejudice exists against
+air-cooling fixed cylinder engines, the Renault has given very good
+service in both England and France.
+
+[Illustration: Fig. 226.--End Sectional View of Renault Air-Cooled
+Aviation Engine.]
+
+[Illustration: Fig. 227.--Side Sectional View of Renault Twelve-Cylinder
+Air-Cooled Aviation Engine Crank-Case, Showing Use of Plain and Ball
+Bearings for Crank-Shaft Support.]
+
+As will be seen by the sectional view at Fig. 227, the steel crank-shaft
+is carried in a combination of plain bearings inside the crank-case and
+by ball bearings at the ends. Owing to air cooling, special precautions
+are taken with the lubrication system, though the lubrication is not
+forced or under high pressure. An oil pump of the gear-wheel type
+delivers oil from the sump at the bottom of the crank-case to a chamber
+above, from which the oil flows by gravity along suitable channels to
+the various main bearings. It flows from the bearings into hollow rings
+fastened to the crank-webs, and the oil thrown from the whirling
+connecting rod big ends bathes the internal parts in an oil mist. In the
+eight-cylinder designs ignition is effected by a magneto giving four
+sparks per revolution and is accordingly driven at engine speed. In the
+twelve-cylinder machine two magnetos of the ordinary revolving armature
+or two-spark type, each supplying six cylinders, are fitted as outlined
+at Fig. 228. The carburetor is a float feed form. Warm air is supplied
+for Winter and damp weather by air pipes surrounding the exhaust pipes.
+The normal speed of the Renault engine is 1,800 R. P. M., but as the
+propeller is mounted upon an extension of the cam-shaft the normal
+propeller speed is but half that of the engine, which makes it possible
+to use a propeller of large diameter and high efficiency. Owing to the
+air cooling, but low compression may be used, this being about 60 pounds
+per square inch, which, of course, lowers the mean effective pressure
+and makes the engine less efficient than water-cooled forms where it is
+possible to use compression pressure of 100 or more pounds per square
+inch. The 70 horse-power engine has cylinders with a bore of 3.78 inches
+and a stroke of 5.52 inches. Its weight is given as 396 pounds, when in
+running order, which figures 5.7 pounds per horse-power. The same
+cylinder size is used on the twelve-cylinder 100 horse-power and the
+stroke is the same. This engine in running order weighs 638 pounds,
+which figures approximately 6.4 pounds per B. H. P.
+
+[Illustration: Fig. 228.--End View of Renault Twelve-Cylinder Engine
+Crank-Case, Showing Magneto Mounting.]
+
+[Illustration: Fig. 229.--Diagram Outlining Renault Twelve-Cylinder
+Engine Ignition System.]
+
+
+SIMPLEX MODEL "A" HISPANO-SUIZA
+
+The Model A is of the water-cooled four-cycle Vee type, with eight
+cylinders, 4.7245 inch bore by 5.1182 inch stroke, piston displacement
+718 cubic inches. At sea-level it develops 150 horse-power at 1,450 R.
+P. M. It can be run successfully at much higher speeds, depending on
+propeller design and gearing, developing proportionately increased
+power. The weight, including carburetor, two magnetos, propeller hub,
+starting magneto and crank, but without radiator, water or oil or
+exhaust pipes, is 445 pounds. Average fuel consumption is .5 pound per
+horse-power hour and the oil consumption at 1,450 R. P. M. is three
+quarts per hour. The external appearance is shown at Fig. 230.
+
+Four cylinders are contained in each block, which is of built-up
+construction; the water jackets and valve ports are cast aluminum and
+the individual cylinders heat-treated steel forgings threaded into the
+bored holes of the aluminum castings. Each block after assembly is given
+a number of protective coats of enamel, both inside and out, baked on.
+Coats on the inside are applied under pressure. The pistons are aluminum
+castings, ribbed. Connecting rods are tubular, of the forked type. One
+rod bears directly on the crank-pin; the other rod has a bearing on the
+outside of the one first mentioned.
+
+The crank-shaft is of the five-bearing type, very short, stiff in
+design, bored for lightness and for the oiling system. The crank-shaft
+extension is tapered for the French standard propeller hub, which is
+keyed and locked to the shaft. This makes possible instant change of
+propellers. The case is in two halves divided on the center line of the
+crank-shaft, the bearings being fitted between the upper and lower
+sections. The lower half is deep, providing a large oil reservoir and
+stiffening the engine. The upper half is simple and provides magneto
+supports on extension ledges of the two main faces. The valves are of
+large diameter with hollow stems, working in cast iron bushings. They
+are directly operated by a single hollow cam-shaft located over the
+valves. The cam-shafts are driven from the crank-shaft by vertical
+shafts and bevel gears. The cam-shafts, cams and heads of the valve
+stems are all enclosed in oil-tight removable housings of cast aluminum.
+
+[Illustration: Fig. 230.--The Simplex Model A Hispano-Suiza Aviation
+Engine, a Very Successful Form.]
+
+Oiling is by a positive pressure system. The oil is taken through a
+filter and steel tubes cast in the case to main bearings, through
+crank-shaft to crank-pins. The fourth main bearing is also provided with
+an oil lead from the system and through tubes running up the end of each
+cylinder block, oil is provided for the cam-shafts, cams and bearings.
+The surplus oil escapes through the end of the cam-shaft where the
+driving gears are mounted, and with the oil that has gathered in the top
+casing, descends through the drive shaft and gears to the sump.
+
+Ignition is by two eight-cylinder magnetos firing two spark-plugs per
+cylinder. The magnetos are driven from each of the two vertical shafts
+by small bevel pinions meshing in bevel gears. The carburetor is mounted
+between the two cylinder blocks and feeds the two blocks through
+aluminum manifolds which are partly water-jacketed. The engine can be
+equipped with a geared hand crank-starting device.
+
+
+STURTEVANT MODEL 5A 140 HORSE-POWER ENGINE
+
+These motors are of the eight-cylinder "V" type, four-stroke cycle,
+water-cooled, having a bore of 4 inches and a stroke of 5-1/2 inches,
+equivalent to 102 mm. x 140 mm. The normal operating speed of the
+crank-shaft is 2,000 R. P. M. The propeller shaft is driven through
+reducing gears which can be furnished in different gear ratios. The
+standard ratio is 5:3, allowing a propeller speed of 1,200 R. P. M.
+
+The construction of the motor is such as to permit of the application of
+a direct drive. The change from the direct drive to gear drive, or vice
+versa, can be accomplished in approximately one hour.
+
+The cylinders are cast in pairs from an aluminum alloy and are provided
+with steel sleeves, carefully fitted into each cylinder. A perfect
+contact is secured between cylinder and sleeve; at the same time a
+sleeve can be replaced without injury to the cylinder proper. No
+difficulties due to expansion occur on account of the rapid transmission
+of heat and the fact that the sleeve is always at higher temperature
+than the cylinder. A moulded copper asbestos gasket is placed between
+the cylinder and the head, permitting the cooling water to circulate
+freely and at the same time insuring a tight joint. The cylinder heads
+are cast in pairs from an aluminum alloy and contain ample water
+passages for circulation of cooling water over the entire head. Trouble
+due to hot valves is thereby eliminated, a most important consideration
+in the operation of an aeroplane motor. The water jacket of the head
+corresponds to the water jacket of the cylinders and large openings in
+both allow the unobstructed circulation of the cooling water. The
+cylinder heads and cylinders are both held to the base by six long
+bolts. The valves are located in the cylinder heads and are mechanically
+operated. The valves and valve springs are especially accessible and of
+such size as to permit high volumetric efficiency. The valves are
+constructed of hardened tungsten steel, the heads and stems being made
+from one piece. The valve rocker arms located on the top of the cylinder
+are provided with adjusting screws. A check nut enables the adjusting
+screw to be securely locked in position, once the correct clearance has
+been determined. The rocker arm bearings are adequately lubricated by a
+compression grease cup. Cam-rollers are interposed between the cams and
+the push rods in order to reduce the side thrust on the push rods.
+
+A system of double springs is employed which greatly reduces the stress
+on each spring and insures utmost reliability. A spring of extremely
+large diameter returns the valve; a second spring located at the
+cylinder base handles the push rod linkage. These springs, which operate
+under low stress, are made from the best of steel and are given a
+special double heat treatment. The pistons are made from a special
+aluminum alloy; are deeply ribbed in the head for cooling and strength
+and provided with two piston rings. These pistons are exceedingly light
+weight in order to minimize vibration and prevent wear on the bearings.
+The piston pin is made of chrome nickel steel, bored hollow and
+hardened. It is allowed to turn, both in piston and connecting rod. The
+piston rings are of special design, developed after years of
+experimenting in aeronautical engines.
+
+The connecting rods are of "H" section, machined all over from forgings
+of a special air-hardening chrome nickel steel which, after being heat
+treated has a tensile strength of 280,000 pounds per square inch. They
+are consequently very strong and yet unusually light, and being machined
+all over are of absolutely uniform section, which gives as nearly
+perfect balance as can be obtained. The big ends are lined with white
+metal and the small ends are bushed with phosphor bronze. The connecting
+rods are all alike and take their bearings side by side on the
+crank-pin, the cylinders being offset to permit of this arrangement. The
+crank-shaft is machined from the highest grade chrome nickel steel, heat
+treated in order to obtain the best properties of this material. It is
+2-1/4 inches in diameter (57 mm.) and bored hollow throughout, insuring
+maximum strength with minimum weight. It is carried in three large,
+bronze-backed white metal bearings. A new method of producing these
+bearings insures a perfect bond between the two metals and eliminates
+breakage.
+
+The base is cast from an aluminum alloy. Great strength and rigidity is
+combined with light weight. The sides extend considerably below the
+center line of the crank-shaft, providing an extremely deep section. At
+all highly stressed points, deep ribs are provided to distribute the
+load evenly and eliminate bending. The lower half of the base is of cast
+aluminum alloy of extreme lightness. This collects the lubricating oil
+and acts as a small reservoir for same. An oil-filtering screen of large
+area covers the entire surface of the sump. The propeller shaft is
+carried on two large annular ball bearings driven from the crank-shaft
+by hardened chrome nickel steel spur gears. These gears are contained
+within an oil-tight casing integral with the base on the opposite end
+from the timing gears. A ball-thrust bearing is provided on the
+propeller shaft to take the thrust of a propeller or tractor, as the
+case may be. In case of the direct drive a stub shaft is fastened direct
+to the crank-shaft and is fitted with a double thrust bearing.
+
+The cam-shaft is contained within the upper half of the base between the
+two groups of cylinders, and is supported in six bronze bearings. It is
+bored hollow throughout and the cams are formed integral with the shaft
+and ground to the proper shape and finish. An important development in
+the shape of cams has resulted in a maintained increase of power at high
+speeds. The gears operating the cam-shaft, magneto, oil and water pumps
+are contained within an oil-tight casing and operate in a bath of oil.
+
+Lubrication is of the complete forced circulating system, the oil being
+supplied to every bearing under high pressure by a rotary pump of large
+capacity. This is operated by gears from the crank-shaft. The oil
+passages from the pump to the main bearings are cast integral with the
+base, the hollow crank-shaft forming a passage through the connecting
+rod bearings and the hollow cam-shaft distributing the oil to the
+cam-shaft bearings. The entire surface of the lower half of the base is
+covered with a fine mesh screen through which the oil passes before
+reaching the pump. Approximately one gallon of oil is contained within
+the base and this is continually circulated through an external tank by
+a secondary pump operated by an eccentric on the cam-shaft. This also
+draws fresh oil from the external tank which can be made of any desired
+capacity.
+
+
+SPECIFICATIONS--MODEL 5A TYPE 8
+
+  Horse-power rating, 140 at 2,000 R. P. M.
+  Bore, 4 inches = 102 mm.
+  Stroke, 5-1/2 inches = 140 mm.
+  Number of cylinders, 8.
+  Arrangement of cylinders, "V."
+  Cooling, water. Circulation by centrifugal pump.
+  Cycle, four stroke.
+  Ignition (double), 2 Bosch or Splitdorf magnetos.
+  Carburetor, Zenith duplex. Water jacket manifold.
+  Oiling system, complete forced. Circulating gear pump.
+  Normal crank-shaft speed, 2,000 R. P. M.
+  Propeller shaft, 3/5 crank-shaft speed at normal, 1,200 R. P. M.
+  Stated power at 30" barometer, 140 B. H. P.
+  Stated weight with all accessories but without water, gasoline or oil,
+  514 pounds = 234 kilos.
+  Weight per B. H. P., 3.7 pounds = 1.68 kilos.
+  Stated weight with all accessories with water, 550 pounds = 250 kilos.
+  Weight per B. H. P. with water, 3.95 pounds = 1.79 kilos.
+
+
+THE CURTISS AVIATION MOTORS
+
+The Curtiss OX motor has eight cylinders, 4-inch bore, 5-inch stroke,
+delivers 90 horse-power at 1,400 turns, and the weight turns out at 4.17
+pounds per horse-power. This motor has cast iron cylinders with monel
+metal jackets, overhead inclined valves operated by means of two rocker
+arms, push-and-pull rods from the central cam-shaft located in the
+crank-case. The cam and push rod design is extremely ingenious and the
+whole valve construction turns out very light. This motor is an
+evolution from the early Curtiss type motor which was used by Glenn
+Curtiss when he won the Gordon Bennett Cup at Rheims. A slightly larger
+edition of this type motor is the OXX-5, as shown at Figs. 231 and 232,
+which has cylinders 4-1/4 inches by 5 inches, delivers 100 horse-power
+at 1,400 turns and has the same fuel and oil consumption as the OX type
+motor, namely, .60 pound of fuel per brake horse-power hour and .03
+pound of lubricating oil per brake horse-power hour.
+
+[Illustration: Fig. 231.--The Curtiss OXX-5 Aviation Engine is an
+Eight-Cylinder Type Largely Used on Training Machines.]
+
+The Curtiss Company have developed in the last two years a larger-sized
+motor now known as the V-2, which was originally rated at 160
+horse-power and which has since been refined and improved so that the
+motor gives 220 horse-power at 1,400 turns, with a fuel consumption of
+52/100 of a pound per brake horse-power hour and an oil consumption of
+.02 of a pound per brake horse-power hour. This larger motor has a
+weight of 3.45 pounds per horse-power and is now said to be giving very
+satisfactory service. The V-2 motor has drawn steel cylinders, with a
+bore of 5 inches and a stroke of 7 inches, with a steel water jacket top
+and a monel metal cylindrical jacket, both of which are brazed on to the
+cylinder barrel itself. Both these motors use side by side connecting
+rods and fully forced lubrication. The cam-shafts act as a gallery from
+which the oil is distributed to the cam-shaft bearings, the main
+crank-shaft bearings, and the gearing. Here again we find extremely
+short rods, which, as before mentioned, enables the height and the
+consequent weight of construction to be very much reduced. For ordinary
+flying at altitudes of 5,000 to 6,000 feet, the motors are sent out with
+an aluminum liner, bolted between the cylinder and the crank-case in
+order to give a compression ratio which does not result in pre-ignition
+at a low altitude. For high flying, however, these aluminum liners are
+taken out and the compression volume is decreased to about 18.6 per
+cent. of the total volume.
+
+[Illustration: Fig. 232.--Top and Bottom Views of the Curtiss OXX-5 100
+Horse-Power Aviation Engine.]
+
+The Curtiss Aeroplane Company announces that it has recently built, and
+is offering, a twelve-cylinder 5" x 7" motor, which was designed for
+aeronautical uses primarily. This engine is rated at 250 horse-power,
+but it is claimed to develop 300 at 1,400 R. P. M. Weights--Motor, 1,125
+pounds; radiator, 120 pounds; cooling water, 100 pounds; propeller, 95
+pounds.
+
+Gasoline Consumption per Horse-power Hour, 6/10 pounds.
+
+Oil Consumption per Hour at Maximum Speed--2 pints.
+
+Installation Dimensions--Overall length, 84-5/8 inches; overall width,
+34-1/8 inches; overall depth, 40 inches; width at bed, 30-1/2 inches;
+height from bed, 21-1/8 inches; depth from bed, 18-1/2 inches.
+
+
+THOMAS-MORSE MODEL 88 ENGINE
+
+The Thomas-Morse Aircraft Corporation of Ithaca, N. Y., has produced a
+new engine, Model 88, bearing a close resemblance to the earlier model.
+The main features of that model have been retained; in fact, many parts
+are interchangeable in the two engines. Supported by the great
+development in the wide use of aluminum, the Thomas engineers have
+adopted this material for cylinder construction, which adoption forms
+the main departure from previous accepted design.
+
+The marked tendency to-day toward a higher speed of rotation has been
+conclusively justified, in the opinion of the Thomas engineers, by the
+continued reliable performance of engines with crank-shafts operating at
+speeds near 2,000 revolutions per minute, driving the propeller through
+suitable gearing at the most efficient speed. High speed demands that
+the closest attention be paid to the design of reciprocating and
+rotating parts and their adjacent units. Steel of the highest
+obtainable tensile strength must be used for connecting rods and piston
+pins, that they may be light and yet retain a sufficient factor of
+safety. Piston design is likewise subjected to the same strict scrutiny.
+At the present day, aluminum alloy pistons operate so satisfactorily
+that they may be said to have come to stay.
+
+The statement often made in the past, that the gearing down of an engine
+costs more in the weight of reduction gears and propeller shaft than is
+warranted by the increase in horse-power, is seldom heard to-day.
+
+The mean effective pressure remaining the same, the brake horse-power of
+any engine increases as the speed. That is, an engine delivering 100
+brake horse-power at 1,500 revolutions per minute will show 133 brake
+horse-power at 2,000 revolutions per minute, an increase of 33 brake
+horse-power. To utilize this increase in horse-power, a matter of some
+fifteen pounds must be spent in gearing and another fifteen perhaps on
+larger valves, bearings, etc. Two per cent. may be assumed lost in the
+gears. In other words, the increase in horse-power due to increasing the
+speed has been attained at the expense of about one pound per brake
+horse-power.
+
+The advantages of the eight-cylinder engine over the six and twelve,
+briefly stated, are: lower weight per horse-power, shorter length,
+simpler and stiffer crank-shaft, cam-shaft and crank-case, and simpler
+and more direct manifold arrangement. As to torque, the eight is
+superior to the six, and yet in practice not enough inferior to the
+twelve to warrant the addition of four more cylinders. It must, however,
+be recognized that the eight is subject to the action of inherent
+unbalanced inertia couples, which set up horizontal vibrations,
+impossible of total elimination. These vibrations are functions of the
+reciprocating weights, which, as already mentioned, are cut down to the
+minimum. Vibrations due to the elasticity of crank-case, crank-shaft,
+etc., can be and are reduced in the Thomas engine to minor quantities by
+ample webbing of the crank-case and judicious use of metal elsewhere.
+All things considered, there is actually so little difference to be
+discerned between the balance of a properly designed eight-cylinder
+engine and that of a six or twelve as to make a discussion of the pros
+and cons more one of theory than of practice.
+
+The main criticisms of the L head cylinder engine are that it is less
+efficient and heavier. This is granted, as it relates to cylinders
+alone. More thorough investigation, however, based on the main
+desideratum, weight-power ratio, leads us to other conclusions,
+particularly with reference to high speed engines. The valve gear must
+not be forgotten. A cylinder cannot be taken completely away from its
+component parts and judged, as to its weight value, by itself alone. A
+part away from the whole becomes an item unimportant in comparison with
+the whole. The valve gear of a high speed engine is a too often
+overlooked feature. The stamp of approval has been made by high speed
+automobile practice upon the overhead cam-shaft drive, with valves in
+the cylinder head operated direct from the cam-shaft or by means of
+valve lifters or short rockers.
+
+The overhead cam-shaft mechanism applied to an eight-cylinder engine
+calls for two separate cam-shafts carried above and supported by the
+cylinders in an oil-tight housing, and driven by a series of spur gears
+or bevels from the crank-shaft. It is patent that this valve gearing is
+heavy and complicated in comparison with the simple moving valve units
+of the L head engine, which are operated from one single cam-shaft,
+housed rigidly in the crank-case. The inherently lower volumetric
+efficiency of the L head engine is largely overcome by the use of a
+properly designed head, large valves and ample gas passages. Again, the
+customary use of a dual ignition system gives to the L head a relatively
+better opportunity for the advantageous placing of spark-plugs, in order
+that better flame propagation and complete combustion may be secured.
+
+[Illustration: Fig. 233.--End View of Thomas-Morse 150 Horse-Power
+Aluminum Cylinder Aviation Motor Having Detachable Cylinder Heads.]
+
+The Thomas Model 88 engine is 4-1/8 inch bore and 5-1/2 inch stroke. The
+cylinders and cylinder heads are of aluminum, and as steel liners are
+used in the cylinders the pistons are also made of aluminum. This engine
+is actually lighter than the earlier model of less power. It weighs but
+525 pounds, with self-starter. The general features of design can be
+readily ascertained by study of the illustrations: Fig. 233, which shows
+an end view; Fig. 234, which is a side view, and Fig. 235, which
+outlines the reduction gear-case and the propeller shaft supporting
+bearings.
+
+[Illustration: Fig. 234.--Side View of Thomas-Morse High Speed 150
+Horse-Power Aviation Motor with Geared Down Propeller Drive.]
+
+
+SIXTEEN-VALVE DUESENBERG ENGINE
+
+[Illustration: Fig. 235.--The Reduction Gear-Case of Thomas-Morse 150
+Horse-Power Aviation Motor, Showing Ball Bearing and Propeller Drive
+Shaft Gear.]
+
+This engine is a four-cylinder, 4-3/4" x 7", 125 horse-power at 2,100 R.
+P. M. of the crank-shaft and 1,210 R. P. M. of the propeller. Motors are
+sold on above rating; actual power tests prove this motor capable of
+developing 140 horse-power at 2,100 R. P. M. of the motor. The exact
+weight with magneto, carburetor, gear reduction and propeller hub, as
+illustrated, 509 pounds; without gear reduction, 436 pounds. This motor
+has been produced as a power plant weighing 3.5 pounds per horse-power,
+yet nothing has been sacrificed in rigidity and strength. At its normal
+speed it develops 1 horse-power for every 3.5 cubic inches piston
+displacement. Cylinders are semi-steel, with aluminum plates enclosing
+water jackets. Pistons specially ribbed and made of Magnalite aluminum
+compound. Piston rings are special Duesenberg design, being three-piece
+rings. Valves are tungsten steel, 1-15/16" inlets and 2" exhausts, two
+of each to each cylinder. Arranged horizontally in the head, allowing
+very thorough water-jacketing. Inlet valves in cages. Exhaust valves,
+seating directly in the cylinder head, are removable through the inlet
+valve holes. Valve stems lubricated by splash in the valve action
+covers. Valve rocker arms forged with cap screw and nut at upper end to
+adjust clearance. Entirely enclosed by aluminum housing, as is entire
+valve mechanism. Connecting rods are tubular, chrome nickel steel, light
+and strong. Crank-shaft is one-piece forging, hollow bored, 2-1/2-inch
+diameter at main bearings. Connecting rod bearings, 2-1/4-inch diameter,
+3 inches long. Front main bearing, 3-1/2 inches long; intermediate main
+bearing, 3-1/2 inches long; rear main bearing, 4 inches long. Crank-case
+of aluminum, barrel type, oil pan on bottom removable. Hand hole plates
+on both sides. Strongly webbed.
+
+The oiling system of this sixteen-valve Duesenberg motor is one of its
+vital features. An oil pump located in the base and submerged in oil
+forces oil through cored passages to the three main bearings, then
+through tubes under each connecting rod into which the rod dips. The oil
+is thrown off from these and lubricates every part of the motor. This
+constitutes the main oiling system; it is supplemented by a splash
+system, there being a trough under each connecting rod into which the
+rod slips. The oil is returned to the main supply sump by gravity, where
+it is strained and re-used. Either system is in itself sufficient to
+operate the motor. A pressure gauge is mounted for observation on a
+convenient part of the system. A pressure of approximately 25 pounds is
+maintained by the pressure system, which insures efficient lubrication
+at all speeds of the motor. The troughs under the connecting rods are so
+constructed that no matter what the angle of flight may be, oil is
+retained in each individual trough so that each connecting rod can dip
+up its supply of oil at each revolution.
+
+
+AEROMARINE SIX-CYLINDER VERTICAL MOTOR
+
+[Illustration: Fig. 236.--The Six-Cylinder Aeromarine Engine.]
+
+These motors are four-stroke cycle, six-cylinder vertical type, with
+cylinder 4-5/16" bore by 5-1/8" stroke. The general appearance of this
+motor is shown in illustration at Fig. 236. This engine is rated at
+85-90 horse-power. All reciprocating and revolving parts of this motor
+are made of the highest grades of steel obtainable as are the studs,
+nuts and bolts. The upper and lower parts of crank-case are made of
+composition aluminum casting. Lower crank-case is made of high grade
+aluminum composition casting and is bolted directly to the upper half.
+The oil reservoir in this lower half casting provides sufficient oil
+capacity for five hours' continuous running at full power. Increased
+capacity can be provided if needed to meet greater endurance
+requirements. Oil is forced under pressure to all bearings by means of
+high-pressured duplex-geared pumps. One side of this pump delivers oil
+under pressure to all the bearings, while the other side draws the oil
+from the splash case and delivers it to the main sump. The oil reservoir
+is entirely separate from the crank-case chamber. Under no circumstances
+will oil flood the cylinder, and the oiling system is not affected in
+any way by any angle of flight or position of motor. An oil pressure
+gauge is placed on instrument board of machine, which gives at all
+times the pressure in oil system, and a sight glass at lower half of
+case indicates the amount of oil contained. The oil pump is external on
+magneto end of motor, and is very accessible. An external oil strainer
+is provided, which is removable in a few minutes' time without the loss
+of any oil. All oil from reservoir to the motor passes through this
+strainer. Pressure gauge feed is also attached and can be piped to any
+part of machine desired.
+
+The cylinders are made of high-grade castings and are machined and
+ground accurately to size. Cylinders are bolted to crank-case with
+chrome nickel steel studs and nuts which securely lock cylinder to upper
+half of crank-case. The main retaining cylinder studs go through
+crank-case and support crank-shaft bearings so that crank-shaft and
+cylinders are tied together as one unit. Water jackets are of copper,
+1/16" thick, electrically deposited. This makes a non-corrosive metal.
+Cooling is furnished by a centrifugal pump, which delivers 25 gallons
+per minute at 1,400 R. P. M. Pistons are made cast iron, accurately
+machined and ground to exact dimensions, which are carefully balanced.
+Piston rings are semi-steel rings of Aeromarine special design.
+
+Connecting rods are of chrome nickel steel, H-section. Crank-shaft is
+made of chrome nickel steel, machined all over, and cut from solid
+billet, and is accurately balanced through the medium of balance weights
+being forged integral with crank. It is drilled for lightness and
+plugged for force feed lubrication. There are seven main bearings to
+crank-shaft. All bearings are of high-grade babbitt, die cast, and are
+interchangeable and easily replaced. The main bearings of the
+crank-shaft are provided with a single groove to take oil under pressure
+from pressure tube which is cast integral with case. Connecting rod
+bearings are of the same type. The gudgeon pin is hardened, ground and
+secured in connecting rod, and is allowed to work in piston. Cam-shaft
+is of steel, with cams forged integral, drilled for lightness and
+forced-feed lubrication, and is case-hardened. The bearings of
+cam-shaft are of bronze. Magneto, two high-tension Bosch D. U. 6. The
+intake manifold for carburetors are aluminum castings and are so
+designed that each carburetor feeds three cylinders, thereby insuring
+easy flow of vapor at all speeds. Weight, 420 pounds.
+
+[Illustration: Fig. 237.--The Wisconsin Aviation Engine, at Top, as
+Viewed from Carburetor Side. Below, the Exhaust Side.]
+
+
+WISCONSIN AVIATION ENGINES
+
+[Illustration: Fig. 238.--Dimensioned End Elevation of Wisconsin Six
+Motor.]
+
+The new six-cylinder Wisconsin aviation engines, one of which is shown
+at Fig. 237, are of the vertical type, with cylinders in pairs and
+valves in the head. Dimensioned drawings of the six-cylinder vertical
+type are given at Figs. 238 and 239. The cylinders are made of aluminum
+alloy castings, are bored and machined and then fitted with hardened
+steel sleeves about 1/16 inch in thickness. After these sleeves have
+been shrunk into the cylinders, they are finished by grinding in place.
+Gray iron valve seats are cast into the cylinders. The valve seats and
+cylinders, as well as the valve ports, are entirely surrounded by water
+jackets. The valves set in the heads at an angle of 25 deg. from the
+vertical, are made of tungsten steel and are provided with double
+springs, the outer or main spring and the inner or auxiliary spring,
+which is used as a precautionary measure to prevent a valve falling into
+the cylinder in remote case of a main spring breaking. The cam-shaft is
+made of one solid forging, case-hardened. It is carried in an aluminum
+housing bolted to the top of the cylinders. This housing is split
+horizontally, the upper half carrying the chrome vanadium steel rocker
+levers. The lower half has an oil return trough cast integral, into
+which the excess oil overflows and then drains back to the crank-case.
+Small inspection plates are fitted over the cams and inner ends of the
+cam rocker levers. The cam-shaft runs in bronze bearings and the drive
+is through vertical shaft and bevel gears.
+
+[Illustration: Fig. 239.--Dimensioned Side Elevation of Wisconsin Six
+Motor.]
+
+The crank-case is made of aluminum, the upper half carrying the
+bearings for the crank-shaft. The lower half carries the oil sump in
+which all of the oil except that circulating through the system at the
+time is carried. The crank-shaft is made of chrome vanadium steel of an
+elastic limit of 115,000 pounds. The crank-pins and ends of the shaft
+are drilled for lightness and the cheeks are also drilled for oil
+circulation. The crank-shaft runs in bronze-backed, Fahrig metal-lined
+bearings, four in number. A double thrust bearing is also provided, so
+that the motor may be used either in a tractor or pusher type of
+machine. Outside of the thrust bearing an annular ball bearing is used
+to take the radial load of the propeller. The propeller is mounted on a
+taper. At the opposite end of the shaft a bevel gear is fitted which
+drives the cam-shaft, through a vertical shaft, and also drives the
+water and oil pumps and magnetos. All gears are made of chrome vanadium
+steel, heat-treated.
+
+The connecting rods are tubular and machined from chrome vanadium steel
+forgings. Oil tubes are fitted to the rods which carry the oil up to the
+wrist-pins and pistons. The rods complete with bushings weigh 5-1/2
+pounds each. The pistons are made of aluminum alloy and are very light
+and strong, weighing only 2 pounds 2 ounces each. Two leak-proof rings
+are fitted to each piston. The wrist-pins are hollow, of hardened steel,
+and are free to turn either in the piston or the rod. A bronze bushing
+is fitted in the upper end of the rod, but no bushing is fitted in the
+pistons, the hardened steel wrist-pins making an excellent bearing in
+the aluminum alloy.
+
+[Illustration: Fig. 240.--Power, Torque and Efficiency Curves of
+Wisconsin Aviation Motor.]
+
+The water circulation is by centrifugal pump, which is mounted at the
+lower end of the vertical shaft. The water is pumped through brass pipes
+to the lower end of the cylinder water jackets and leaves the upper end
+of the jackets just above the exhaust valves. The lubricating system is
+one of the main features of the engines, being designed to work with the
+motor at any angle. The oil is carried in the sump, from where it is
+taken by the oil circulating pump through a strainer and forced through
+a header, extending the full length of the crank-case, and distributed
+to the main bearings. From the main bearings it is forced through the
+hollow crank-shaft to the connecting rod big ends and then through
+tubes on the rods to wrist-pins and pistons. Another lead takes oil from
+the main header to the cam-shaft bearings. The oil forced out of the
+ends of the cam-shaft bearings fills pockets under the cams and in the
+cam rocker levers. The excess flows back through pipes and through the
+train of gears to the crank-case. A strainer is fitted at each end of
+the crank-case, through which the oil is drawn by separate pumps and
+returned to the sump. Either one of these pumps is large enough to take
+care of all of the return oil, so that the operation is perfect whether
+the motor is inclined up or down. No splash is used in the crank-case,
+the system being a full force feed. An oil level indicator is provided,
+showing the amount of oil in the sump at all times. The oil pressure in
+these motors is carried at ten pounds, a relief valve being fitted to
+hold the pressure constant.
+
+[Illustration: Fig. 241.--Timing Diagram, Wisconsin Aviation Engine.]
+
+Ignition is by two Bosch magnetos, each on a separate set of plugs fired
+simultaneously on opposite sides of the cylinders. Should one magneto
+fail, the other would still run the engine at only a slight loss in
+power. The Zenith double carburetor is used, three cylinders being
+supplied by each carburetor. This insures a higher volumetric
+efficiency, which means more power, as there is no overlapping of inlet
+valves whatever by this arrangement. All parts of these motors are very
+accessible. The water and oil pumps, carburetors, magnetos, oil strainer
+or other parts can be removed without disturbing other parts. The lower
+crank-case can be removed for inspection or adjustment of bearings, as
+the crank-shaft and bearing caps are carried by the upper half. The
+motor supporting lugs are also part of the upper crank-case.
+
+The six-cylinder motor, without carburetors or magnetos, weighs 547
+pounds. With carburetor and magnetos, the weight is 600 pounds. The
+weight of cooling water in the motor is 38 pounds. The sump will carry 4
+gallons of oil, or about 28 pounds. A radiator can be furnished suitable
+for the motor, weighing 50 pounds. This radiator will hold 3 gallons of
+water or about 25 pounds. The motor will drive a two-blade, 8 feet
+diameter by 6.25 feet pitch Paragon propeller 1400 revolutions per
+minute, developing 148 horse-power. The weight of this propeller is 42
+pounds. This makes a total weight of motor, complete with propeller,
+radiator filled with water, but without lubricating oil, 755 pounds, or
+about 5.1 pounds per horse-power for complete power plant. The fuel
+consumption is .5 pound per horse-power per hour. The lubricating oil
+consumption is .0175 pound per horse-power per hour, or a total of 2.6
+pounds per hour at 1400 revolutions per minute. This would make the
+weight of fuel and oil, per hour's run at full power at 1400 revolutions
+per minute, 76.6 pounds.
+
+
+PRINCIPAL DIMENSIONS
+
+Following are the principal dimensions of the six-cylinder motor:
+
+  Bore 5 inches.
+  Stroke 6-1/2 inches.
+  Crank-shaft diameter throughout 2 inches.
+  Length of crank-pin and main bearings 3-1/2 inches.
+  Diameter of valves 3 inches (2-3/4 inches clear).
+  Lift of valves 1/2 inch.
+  Volume of compression space 22 per cent. of total.
+  Diameter of wrist-pins 1-3/16 inches.
+  Firing order 1-4-2-6-3-5.
+
+The horse-power developed at 1200 revolutions per minute is 130, at 1300
+revolutions per minute 140, at 1400 revolutions per minute 148. 1400 is
+the maximum speed at which it is recommended to run these motors.
+
+
+TWELVE-CYLINDER ENGINE
+
+A twelve-cylinder V-type engine illustrated, is also being built by this
+company, similar in dimensions of cylinders to the six. The principal
+differences being in the drive to cam-shaft, which is through spur gears
+instead of bevel. A hinged type of connecting rod is used which does not
+increase the length of the motor and, at the same time, this
+construction provides for ample bearings. A double centrifugal water
+pump is provided for this motor, so as to distribute the water uniformly
+to both sets of cylinders. Four magnetos are used, two for each set of
+six cylinders. The magnetos are very accessibly located on a bracket on
+the spur gear cover. The carburetors are located on the outside of the
+motors, where they are very accessible, while the exhaust is in the
+center of the valley. The crank-shaft on the twelve is 2-1/2 inches in
+diameter and the shaft is bored to reduce weight. Dimensioned drawings
+of the twelve-cylinder engine are given at Figs. 242 and 243 and should
+prove useful for purposes of comparison with other motors.
+
+
+HALL-SCOTT AVIATION ENGINES
+
+The following specifications of the Hall-Scott "Big Four" engines apply
+just as well to the six-cylinder vertical types which are practically
+the same in construction except for the structural changes necessary to
+accommodate the two extra cylinders. Cylinders are cast separately from
+a special mixture of semi-steel, having cylinder head with valve seats
+integral. Special attention has been given to the design of the water
+jacket around the valves and head, there being two inches of water space
+above same. The cylinder is annealed, rough machined, then the inner
+cylinder wall and valve seats ground to mirror finish. This adds to the
+durability of the cylinder, and diminishes a great deal of the excess
+friction.
+
+[Illustration: Fig. 242.--Dimensioned End View of Wisconsin
+Twelve-Cylinder Airplane Motor.]
+
+Great care is taken in the casting and machining of these cylinders, to
+have the bore and walls concentric with each other. Small ribs are cast
+between outer and inner walls to assist cooling as well as to transfer
+stresses direct from the explosion to hold-down bolts which run from
+steel main bearing caps to top of cylinders. The cylinders are machined
+upon the sides so that when assembled on the crank-case with grooved
+hold-down washers tightened, they form a solid block, greatly assisting
+the rigidity of crank-case.
+
+[Illustration: Fig. 243.--Dimensioned Side Elevation of Wisconsin
+Twelve-Cylinder Airplane Motor.]
+
+The connecting rods are very light, being of the I beam type, milled
+from a solid Chrome nickel die forging. The caps are held on by two
+1/2"-20 thread Chrome nickel through bolts. The rods are first roughed
+out, then annealed. Holes are drilled, after which the rods are hardened
+and holes ground parallel with each other. The piston end is fitted with
+a gun metal bushing, while the crank-pin end carries two bronze serrated
+shells, which are tinned and babbitted hot, being broached to harden the
+babbitt. Between the cap and rod proper are placed laminated shims for
+adjustment. Crank-cases are cast of the best aluminum alloy, hand
+scraped and sand blasted inside and out. The lower oil case can be
+removed without breaking any connections, so that the connecting rods
+and other working parts can readily be inspected. An extremely large
+strainer and dirt trap is located in the center and lowest point of the
+case, which is easily removed from the outside without disturbing the
+oil pump or any working parts. A Zenith carburetor is provided.
+Automatic valves and springs are absent, making the adjustment simple
+and efficient. This carburetor is not affected by altitude to any
+appreciable extent. A Hall-Scott device, covered by U. S. Patent No.
+1,078,919, allows the oil to be taken direct from the crank-case and run
+around the carburetor manifold, which assists carburetion as well as
+reduces crank-case heat. Two waterproof four-cylinder Splitdorf "Dixie"
+magnetos are provided. Both magneto interruptors are connected to a rock
+shaft integral with the motor, making outside connections unnecessary.
+It is worthy of note that with this independent double magneto system,
+one complete magneto can become inoperative, and still the motor will
+run and continue to give good power.
+
+The pistons as provided in the A-7 engines are cast from a mixture of
+steel and gray iron. These are extremely light, yet provided with six
+deep ribs under the arch head, greatly aiding the cooling of the piston
+as well as strengthening it. The piston pin bosses are located very low
+in order to keep the heat from the piston head away from the upper end
+of the connecting rod, as well as to arrange them at the point where the
+piston fits the cylinder best. Three 1/4" rings are carried. The pistons
+as provided in the A-7a engines are cast from aluminum alloy. Four 1/4"
+rings are carried. In both piston types a large diameter, heat treated,
+Chrome nickel steel wrist-pin is provided, assembled in such a way as to
+assist the circular rib between the wrist-pin bosses to keep the piston
+from being distorted from the explosions.
+
+The oiling system is known as the high pressure type, oil being forced
+to the under side of the main bearings with from 5 to 30 points
+pressure. This system is not affected by extreme angles obtained in
+flying, or whether the motor is used for push or pull machines. A large
+gear pump is located in the lowest point of the oil sump, and being
+submerged at all times with oil, does away with troublesome stuffing
+boxes and check valves. The oil is first drawn from the strainer in oil
+sump to the long jacket around the intake manifold, then forced to the
+main distributor pipe in crank-case, which leads to all main bearings. A
+bi-pass, located at one end of the distributor pipe, can be regulated to
+provide any pressure required, the surplus oil being returned to the
+case. A special feature of this system is the dirt, water and sediment
+trap, located at the bottom of the oil sump. This can be removed without
+disturbing or dismantling the oil pump or any oil pipes. A small oil
+pressure gauge is provided, which can be run to the aviator's instrument
+board. This registers the oil pressure, and also determines its
+circulation.
+
+The cooling of this motor is accomplished by the oil as well as the
+water, this being covered by patent No. 1,078,919. This is accomplished
+by circulating the oil around a long intake manifold jacket; the
+carburetion of gasoline cools this regardless of weather conditions.
+Crank-case heat is therefore kept at a minimum. The uniform temperature
+of the cylinders is maintained by the use of ingenious internal outlet
+pipes, running through the head of each of the six-cylinders, rubber
+hose connections being used so that any one of the cylinders may be
+removed without disturbing the others. Slots are cut in these pipes so
+that cooler water is drawn directly around the exhaust valves. Extra
+large water jackets are provided upon the cylinders, two inches of water
+space is left above the valves and cylinder head. The water is
+circulated by a large centrifugal pump insuring ample circulation at all
+speeds.
+
+The crank-shaft is of the five bearing type, being machined from a
+special heat treated drop forging of the highest grade nickel steel. The
+forging is first drilled, then roughed out. After this the shaft is
+straightened, turned down to a grinding size, then ground accurately to
+size. The bearing surfaces are of extremely large size, over-size,
+considering general practice in the building of high speed engines of
+similar bore and stroke. The crank-shaft bearings are 2" in diameter by
+1-15/16" long, excepting the rear main bearing, which is 4-3/8" long,
+and front main bearing, which is 2-3/16" long. Steel oil scuppers are
+pinned and sweated onto the webs of the shaft, which allows of properly
+oiling the connecting rod bearings. Two thrust bearings are installed on
+the propeller end of the shaft, one for pull and the other for push. The
+propeller is driven by the crank-shaft flange, which is securely held in
+place upon the shaft by six keys. These drive an outside propeller
+flange, the propeller being clamped between them by six through bolts.
+The flange is fitted to a long taper on crank-shaft. This enables the
+propeller to be removed without disturbing the bolts. Timing gears and
+starting ratchets are bolted to a flange turned integral with shaft.
+
+The cam-shaft is of the one piece type, air pump eccentric, and gear
+flange being integral. It is made from a low carbon specially heat
+treated nickel forging, is first roughed out and drilled entire length;
+the cams are then formed, after which it is case hardened and ground to
+size. The cam-shaft bearings are extra long, made from Parson's White
+Brass. A small clutch is milled in gear end of shaft to drive revolution
+indicator. The cam-shaft is enclosed in an aluminum housing bolted
+directly on top of all six cylinders, being driven by a vertical shaft
+in connection with bevel gears. This shaft, in conjunction with rocker
+arms, rollers and other working parts, are oiled by forcing the oil into
+end of shaft, using same as a distributor, allowing the surplus supply
+to flow back into the crank-case through hollow vertical tube. This
+supply oils the magneto and pump gears. Extremely large Tungsten valves,
+being one-half the cylinder diameter, are seated in the cylinder heads.
+Large diameter oil tempered springs held in tool steel cups, locked with
+a key, are provided. The ports are very large and short, being designed
+to allow the gases to enter and exhaust with the least possible
+resistance. These valves are operated by overhead one piece cam-shaft in
+connection with short Chrome nickel rocker arms. These arms have
+hardened tool steel rollers on cam end with hardened tool steel
+adjusting screws opposite. This construction allows accurate valve
+timing at all speeds with least possible weight.
+
+
+CENSORED
+
+
+GERMAN AIRPLANE MOTORS
+
+In a paper on "Aviation Motors," presented by E. H. Sherbondy before the
+Cleveland section of the S. A. E. in June, 1917, the Mercedes and Benz
+airplane motor is discussed in some detail and portions of the
+description follow.
+
+[Illustration: Fig. 244.--Side and End Sectional Views of Four-Cylinder
+Argus Engine, a German 100 Horse-Power Design Having Bore and Stroke of
+140 mm., or 5.60 inches, and Developing Its Power at 1,368 R.P.M.
+Weight, 350 Pounds.]
+
+
+MERCEDES MOTOR
+
+The 150 horse-power six-cylinder Mercedes motor is 140 millimeters bore
+and 160 millimeters stroke. The Mercedes company started with
+smaller-sized cylinders, namely 100 millimeters bore and 140 millimeters
+stroke, six-cylinders. The principal features of the design are forged
+steel cylinders with forged steel elbows for gas passages, pressed steel
+water jackets, which when welded together forms the cylinder
+assembly, the use of inclined overhead valves operated by means of an
+overhead cam-shaft through rocker arms which multiply with the motion of
+the cam. By the use of steel cylinders, not only is the weight greatly
+reduced, but certain freedom from distortion through unequal sections,
+leaks and cracks are entirely avoided. The construction is necessarily
+very expensive. It is certainly a sound job. In the details of this
+construction there are a number of important things, such as finished
+gas passages, water-cooled valve guides and a very small mass of metal,
+which is water-cooled, surrounding the spark-plug. Of course, it is
+necessary to use very high compression in aviation motors in order to
+secure high power and economy and owing to the fact that aviation motors
+are worked at nearly their maximum, the heat flow through the cylinder,
+piston, and valves is many times higher than that encountered in
+automobile motors. It has been found necessary to develop special types
+of pistons to carry the heat from the center of the head in order to
+prevent pre-ignition. In the Mercedes motor the pistons have a drop
+forged steel head which includes the piston boss and this head is
+screwed into a cast iron skirt which has been machined inside to secure
+uniform wall thickness.
+
+
+CENSORED
+
+
+  [A] Piston Displacement (Cubic Inches)
+  [B] Weight of Engine with Carburetor and Ignition
+  [C] Gas Consumption
+
+  ===========+======+======+======+=======+====+======+====+=================
+  Maker's    |Number|Bore  |Stroke|       |    |      |    |
+  Name       |  of  |(In-  |(In-  |       |    |      |    |
+  and Model  | Cyl. |ches) |ches) |  [A]  |H.P.|R.P.M.| [B]|       [C]
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Aeromarine |   6  |4-1/2 |5-1/8 | 449   |  85| 1400 | 440|       ...
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Aeromarine |  12  |4-5/16|5-1/8 |  ...  | ...| ...  | 750|       ...
+  D-12       |      |      |      |       |    |      |    |
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Curtiss OX |   8  |4     |5     | 502.6 |  90| 1400 | 375|       ...
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Curtiss    |   8  |4-1/4 |5     | 567.5 | 100| 1400 | 423|       ...
+  OXX-2      |      |      |      |       |    |      |    |
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Curtiss V-2|   8  |5     |7     |1100   | 200| 1400 | 690|       ...
+  -----------+------+------+------+-------+----+------+----+-----------------
+                                   CENSORED
+  -----------+------+------+------+-------+----+------+----+-----------------
+  General Ve-|   9  |4.33  |5.9   | 848   | 100| 1200 | 272|12 gals/hour at
+  hicle Gnome Mono  |      |      |       |    |      |    |rated H.P.
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Gyro K     |   7  |4-1/2 |6     | ...   |  90|  1250| 215|8 gals/hour at
+  Rotary, Le Rhone Type    |      |       |    |      |    |rated H.P.
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Gyro L     |   9  |4-1/2 |6     | 859   | 100|  1200| 285|10 gals/hour at
+  Rotary, Le Rhone Type    |      |       |    |      |    |rated H.P.
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Hall-Scott |   4  |5     |7     | 550   | 90-|  1400| 410|       ...
+  A-7        |      |      |      |       | 100|      |    |
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Hall-Scott |   6  |5     |7     | 825   | 125|  1300| 592|       ...
+  A-5        |      |      |      |       |    |      |    |
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Hispano-   |   8  |4-5/8 |5     | 672   | 154|  1500| 455|       ...
+  Suiza      |      |      |      |       |    |      |    |
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Knox Motors|  12  |4-3/4 |7     |1555   | 300|  1800|1425|31.5 gals/hour
+  Co.        |      |      |      |       |    |      |    |
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Maximotor  |   6  |4-1/2 |5     | 477   |  85|  1600| 340|       ...
+  A-6        |      |      |      |       |    |      |    |
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Maximotor  |   6  |5     |6     | 706.8 | 115|  1600| 385|       ...
+  B-6        |      |      |      |       |    |      |    |
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Maximotor  |   8  |4-1/2 |5     | 636   | 115|  1600| 420|       ...
+  A-8        |      |      |      |       |    |      |    |
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Packard 12 |  12  |4     |6     | 903   | 225|  2100| 800|       ...
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Sturtevant |   8  |4     |5-1/2 | 552.9 | 140|  2000| 580|       ...
+  5          |      |      |      |       |    |      |    |
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Sturtevant |   8  |4     |5-1/2 | ...   | 140|  2000| 514|13.75 gals/hour
+  5-A        |      |      |      |       |    |      |    |
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Thomas 8   |   8  |4     |5-1/2 | 552.9 | 135|  2000| 630|       ...
+             |      |      |      |       |    |      |lbs. with self-starter
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Thomas 88  |   8  |4-1/8 |5-1/2 | 552.9 | 150|  2100| 525|       ...
+             |      |      |      |       |    |      |lbs. with self-starter
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Wisconsin  |   6  |5     |6-1/2 | 765.7 | 140|  1380| 637|       ...
+  -----------+------+------+------+-------+----+------+----+-----------------
+  Wisconsin  |  12  |5     |6-1/2 |1531.4 | 250|  1200| ...|       ...
+  -----------+------+------+------+-------+----+------+----+-----------------
+
+The carburetor used on this 150 horse-power Mercedes motor is precisely
+of the same type used on the Twin Six motor. It has two venturi throats,
+in the center of which is placed the gasoline spray nozzle of
+conventional type, fixed size orifices, immediately above which are
+placed two panel type throttles with side outlets. An idling or primary
+nozzle is arranged to discharge above the top of the venturi throat. The
+carburetor body is of cast aluminum and is water jacketed. It is bolted
+directly to air passage passing through the top and bottom half of the
+crank-case which passes down through the oil reservoir. The air before
+reaching the carburetor proper to some extent has cooled the oil in the
+crank chamber and has itself been heated to assist in the vaporization.
+The inlet pipes themselves are copper. All the passages between the
+venturi throat and the inlet valve have been carefully finished and
+polished. The only abnormal thing in the design of this motor is the
+short connecting rod which is considerably less than twice the stroke
+and would be considered very bad practice in motor car engines. A short
+connecting rod, however, possesses two very real virtues in that it cuts
+down height of the motor and the piston passes over the bottom dead
+center much more slowly than with a long rod.
+
+[Illustration: Fig. 245.--Part Sectional View of 90 Horse-Power Mercedes
+Engine, Which is Typical of the Design of Larger Sizes.]
+
+Other features of the design are a very stiff crank-case, both halves of
+which are bolted together by means of long through bolts, the
+crank-shaft main bearings are seated in the lower half of the case
+instead of in the usual caps and no provision is made for taking up the
+main bearings. The Mercedes company uses a plunger type of pump having
+mechanically operated piston valves and it is driven by means of worm
+gearing.
+
+The overhead cam-shaft construction is extremely light. The cam-shaft is
+mounted in a nearly cylindrical cast bronze case and is driven by means
+of bevel gears from the crank-shaft. The vertical bevel gear shaft
+through which the drive is taken from the crank-shaft to the cam-shaft
+operates at one and one-half times the crank-shaft speeds and the
+reduction to the half-time cam-shaft is secured through a pair of
+bevels. On this vertical shaft there is mounted the water pump and a
+bevel gear for driving two magnetos. The water pump mounted on this
+shaft tends to steady the drive and avoid vibration in the gearing.
+
+The cylinder sizes of six-cylinder aviation motors which have been built
+by Mercedes are
+
+   Bore      Stroke    Horse-power
+  105 mm.    140 mm.       100
+  120 mm.    140 mm.       135
+  140 mm.    150 mm.       150
+  140 mm.    160 mm.       160
+
+The largest of these motors has recently had its horse-power increased
+to 176 at 1450 R. P. M. This general design of motor has been the
+foundation for a great many other aviation motor designs, some of which
+have proved very successful but none of which is equal to the original.
+Among the motors which follow more or less closely the scheme of design
+and arrangement are the Hall-Scott, the Wisconsin motor, the Renault
+water-cooled, the Packard, the Christofferson and the Rolls-Royce. Each
+of these motors show considerable variation in detail. The Rolls-Royce
+and Renault are the only ones who have used the steel cylinder with the
+steel jacket. The Wisconsin motor uses an aluminum cylinder with a
+hardened steel liner and cast-iron valve seats. The Christofferson has
+somewhat similar design to the Wisconsin with the exception that the
+valve seats are threaded into the aluminum jacket and the cylinder head
+has a blank end which is secured to the aluminum casting by means of the
+valve seat pieces. The Rolls-Royce motors show small differences in
+details of design in cylinder head and cam-shaft housing from the
+Mercedes on which it has taken out patents, not only abroad but in this
+country.
+
+
+THE BENZ MOTOR
+
+In the Kaiser prize contest for aviation motors a four-cylinder Benz
+motor of 130 by 180 mm. won first prize, developing 103 B. H. P. at 1290
+R. P. M. The fuel consumption was 210 grams per horse-power hour. Total
+weight of the motor was 153 kilograms. The oil consumption was .02 of a
+kilogram per horse-power hour. This motor was afterward expanded into a
+six-cylinder design and three different sizes were built.
+
+The accompanying table gives some of the details of weight, horse-power,
+etc.
+
+  Motor type                                    B      FD      FF
+  Rated horse-power                            85     100     150
+  Horse-power at 1250 r.p.m                    88     108     150
+  Horse-power at 1350 r.p.m                    95     115     160
+  Bore in millimeters                         106     116     130
+  Stroke in millimeters                       150     160     180
+  Offset of the cylinders in millimeters       18      20      20
+  Rate of gasoline consumption in grams       240     230     225
+  Oil consumption in grams per b.h.p. hour     10      10      10
+  Oil capacity in kilograms                    36       4       4-1/2
+  Water capacity in litres                      5-1/2   7-1/2   9-1/2
+  The weight with water and oil but with
+  two magnetos, fuel feeder and air pump in
+  kilograms                                   170     200     245
+  The weight of motors, including the water
+  pump, two magnetos, double ignition, etc.   160     190     230
+  The weight of the exhaust pipe, complete
+  in kilograms                                  4       4.8     5-1/2
+  The weight of the propeller hub in
+  kilograms.                                    3-1/2   4       4
+
+The Benz cylinder is a simple, straightforward design and a very
+reliable construction and not particularly difficult to manufacture. The
+cylinder is cast of iron without a water jacket but including 45
+degrees angle elbows to the valve ports. The cylinders are machined
+wherever possible and at other points have been hand filed and scraped,
+after which a jacket, which is pressed in two halves, is gas welded by
+means of short pipes welded on to the jacket. The bottom and the top of
+the cylinders become water galleries, and by this means separate water
+pipes with their attendant weight and complication are eliminated.
+Rubber rings held in aluminum clamps serve to connect the cylinders
+together. The whole construction turns out very neat and light. The
+cylinder walls are 4 mm. or 3/16" thick and the combustion chamber is of
+cylindrical pancake form and is 140 mm. or 5.60 inch in diameter. The
+valve seats are 68 mm. in diameter and the valve port is 62 mm. in
+diameter.
+
+The passage joining the port is 57 mm. in diameter. In order to insert
+the valves into the cylinder the valve stem is made with two diameters
+and the valve has to be cocked to insert it in the guide, which has a
+bronze bushing at its upper end to compensate for the smaller valve stem
+diameter. The valve stem is 14 mm. or 9/16" in diameter and is reduced
+at its upper portion to 9-1/2 mm. The valves are operated through a push
+rod and rocker arm construction, which is 7/16" and exceedingly light.
+Rocker arm supports are steel studs with enlarged heads to take a double
+row ball bearing. A roller is mounted at one end of the rocker arm to
+impinge on the end of the valve stem, and the rocker arm has an
+adjustable globe stud at the other end. The push rods are light steel
+tubes with a wall thickness of 0.75 mm. and have a hardened steel cup at
+their upper end to engage the rocker arm globe stud and a hardened steel
+globe at their lower end to socket in the roller plunger.
+
+The Benz cam-shaft has a diameter of 26 mm. and is bored straight
+through 18 mm. and there is a spiral gear made integrally with the shaft
+in about the center of its length for driving the oil pump gear. The cam
+faces are 10 mm. wide. There is also, in addition to the intake and
+exhaust cams, a set of half compression cams. The shaft is moved
+longitudinally in its bearings by means of an eccentric to put these
+cams into action. At the fore end of the shaft is a driving gear flange
+which is very small in diameter and very thin. The flange is 68 mm. in
+diameter and 4 mm. thick and is tapped to take 6 mm. bolts. The total
+length of cam-shaft is 1038 mm., and it becomes a regular gun boring job
+to drill a hole of this length.
+
+The cam-shaft gear is 140 mm. or 5-1/2 inches outside diameter. It has
+fifty-four teeth and the gear face is 15 mm. or 19/32". The flange and
+web have an average thickness of 4 mm. or 5/32" and the web is drilled
+full of holes interposed between the spur gear mounted on the cam-shaft
+and the cam-shaft gear. There is a gear which serves to drive the
+magnetos and tachometer, also the air pump. The shaft is made integrally
+with this gear and has an eccentric portion against which the air pump
+roll plunger impinges.
+
+The seven-bearing crank-shaft is finished all over in a beautiful
+manner, and the shaft out of the particular motor we have shows no signs
+of wear whatever. The crank-pins are 55 mm. in diameter and 69 mm. long.
+Through both the crank-pin and main bearings there is drilled a 28 mm.
+hole, and the crank cheeks are plugged with solder. The crank cheeks are
+also built to convey the lubricant to the crank-pins. At the fore end of
+the crank cheek there is pressed on a spur driving gear. There is
+screwed on to the front end of the shaft a piece which forms a bevel
+water pump driving gear and the starting dog. At the rear end of the
+shaft very close to the propeller hub mounting there is a double thrust
+bearing to take the propeller thrust.
+
+Long, shouldered studs are screwed into the top half of the crank-case
+portion of the case and pass clean through the bottom half of the case.
+The case is very stiff and well ribbed. The three center bearing
+diaphragms have double walls. The center one serves as a duct through
+which water pipe passes, and those on either side of the center form the
+carburetor intake air passages and are enlarged in section at one side
+to take the carburetor barrel throttle.
+
+The pistons are of cast iron and carry three concentric rings 1/4 inch
+wide on their upper end, which are pinned at the joint. The top of the
+piston forms the frustum of the cone and the pistons are 110 mm. in
+length. The lower portion of the skirt is machined inside and has a wall
+thickness of 1 mm. Riveted to the piston head is a conical diaphragm
+which contacts with the piston pin when in place and serves to carry the
+heat off the center of the piston.
+
+The oil pump assembly comprises a pair of plunger pumps which draw oil
+from a separate outside pump, and constructed integrally with it is a
+gear pump which delivers the oil under about 60 pound pressure through a
+set of copper pipes in the base to the main bearings. The plunger oil
+pump shows great refinement of detail. A worm wheel and two eccentrics
+are machined up out of one piece and serve to operate the plungers.
+
+[Illustration: Fig. 246.--Part Sectional Side View and Sectional End
+View of Benz 160 Horse-Power Aviation Engine.]
+
+Some interesting details of the 160 horse-power Benz motor, which is
+shown at Fig. 246, are reproduced from the "Aerial Age Weekly," and show
+how carefully the design has been considered.
+
+  Maximum horse-power, 167.5 B. H. P.
+  Speed at maximum horse-power, 1,500 R. P. M.
+  Piston speed at maximum horse-power, 1,770 ft. per minute.
+  Normal horse-power, 160 B. H. P.
+  Speed at normal horse-power, 1,400 R. P. M.
+  Piston speed at normal horse-power, 1,656 ft. per minute.
+  Brake mean pressure at maximum horse-power, 101.2 pound per square
+  inch.
+  Brake mean pressure at normal horse-power, 103.4 pound per square
+  inch.
+  Specific power cubic inch swept volume per B. H. P., 5.46 cubic inch;
+  160 B. H. P.
+  Weight of piston, complete with gudgeon pin, rings, etc., 5.0 pound.
+  Weight of connecting rod, complete with bearings, 4.99 pound; 1.8
+  pound reciprocating.
+  Weight of reciprocating parts per cylinder, 6.8 pound.
+  Weight of reciprocating parts per square inch of piston area, 0.33
+  pound.
+  Outside diameter of inlet valve, 68 mm.; 2.68 inches.
+  Diameter of inlet valve port (_d_), 61.5 mm.; 2.42 inches.
+  Maximum lift of inlet valve (_h_), 11 mm.; 0.443 inch.
+  Area of inlet valve opening ([pi] _d_ _h_), 21.25 square cm.; 3.29
+  square inches.
+  Inlet valve opens, degrees on crank, top dead center.
+  Inlet valve closes, degrees on crank, 60 deg. late; 35 mm. late.
+  Outside diameter of exhaust valve, 68 mm.; 2.68 inches.
+  Diameter of exhaust valve port (_d_), 61.5 mm.; 2.42 inches.
+  Maximum lift of exhaust valve (_h_) 11 mm.; 0.433 inch.
+  Area of exhaust valve opening ([pi] _d_ _h_), 21.25 square cm.; 3.29
+  square inches.
+  Exhaust valve opens, degrees on crank, 60 deg. early; 35 mm. early.
+  Exhaust valve closes, degrees on crank, 16-1/2 deg. late; 5 mm. late.
+  Length of connecting rod between centers, 314 mm.; 12.36 inches.
+  Ratio connecting rod to crank throw, 3.49:1.
+  Diameter of crank-shaft, 55 mm. outside, 2.165 inches; 28 mm. inside,
+  1.102 inches.
+  Diameter of crank-pin, 55 mm. outside, 2.165 inches; 28 mm. inside,
+  1.102 inches.
+  Diameter of gudgeon pin, 30 mm. outside, 1.181 inches; 19 mm. inside,
+  0.708 inch.
+  Diameter of cam-shaft, 26 mm. outside, 1.023 inches; 18 mm. inside,
+  0.708 inch.
+  Number of crank-shaft bearings, 7.
+  Projected area of crank-pin bearings, 36.85 square cm.; 5.72 square
+  inches.
+  Projected area of gudgeon pin bearings, 22.20 square cm.; 3.44 square
+  inches.
+  Firing sequence, 1, 5, 3, 6, 2, 4.
+  Type of magnetos, ZH6 Bosch.
+  Direction of rotation of magneto from driving end, one clock, one
+  anti-clock.
+  Magneto timing, full advance, 30 deg. early (16 mm. early).
+  Type of carburetors (2) Benz design.
+  Fuel consumption per hour, normal horse-power, 0.57 pint.
+  Normal speed of propeller, engine speed, 1,400 R. P. M.
+
+
+AUSTRO-DAIMLER ENGINE
+
+One of the first very successful European flying engines which was
+developed in Europe is the Austro-Daimler, which is shown in end section
+in a preceding chapter. The first of these motors had four-cylinders,
+120 by 140 millimeters, bore and stroke, with cast iron cylinders,
+overhead valves operated by means of a single rocker arm, controlled by
+two cams and the valves were closed by a single leaf spring which
+oscillates with the rocker arm. The cylinders are cast singly and have
+either copper or steel jackets applied to them. The four-cylinder design
+was afterwards expanded to the six-cylinder design and still later a
+six-cylinder motor of 130 by 175 millimeters was developed. This motor
+uses an offset crank-shaft, as does the Benz motor, and the effect of
+offset has been discussed earlier on in this treatise. The Benz motor
+also uses an offset cam-shaft which improves the valve operation and
+changes the valve lift diagram. The lubrication also is different than
+any other aviation motor, since individual high pressure metering pumps
+are used to deliver fresh oil only to the bearings and cylinders, as was
+the custom in automobile practice some ten years ago.
+
+
+SUNBEAM AVIATION ENGINES
+
+These very successful engines have been developed by Louis Coatalen. At
+the opening of the war the largest sized Coatalen motor was 225
+horse-power and was of the L-head type having a single cam-shaft for
+operating valves and was an evolution from the twelve-cylinder racing
+car which the Sunbeam Company had previously built. Since 1914 the
+Sunbeam Company have produced engines of six-, eight-, twelve- and
+eighteen-cylinders from 150 to 500 horse-power with both iron and
+aluminum cylinders. For the last two years all the motors have had
+overhead cam-shafts with a separate shaft for operating the intake and
+exhaust valves. Cam-shafts are connected through to the crank-shaft by
+means of a train of spur gears, all of which are mounted on two double
+row ball bearings. In the twin six, 350 horse-power engine, operating at
+2100 R. P. M., requires about 4 horse-power to operate the cam-shafts.
+This motor gives 362 horse-power at 2100 revolutions and has a fuel
+consumption of 51/100 of a pint per brake horse-power hour. The
+cylinders are 110 by 160 millimeters. The same design has been expanded
+into an eighteen-cylinder which gives 525 horse-power at 2100 turns.
+There has also been developed a very successful eight-cylinder motor
+rated at 2220 horse-power which has a bore and stroke of 120 by 130
+millimeters, weight 450 pounds. This motor is an aluminum block
+construction with steel sleeves inserted. Three valves are operated, one
+for the inlet and two for the exhaust. One cam-shaft operates the three
+valves.
+
+[Illustration: Fig. 247.--At Top, the Sunbeam Overhead Valve 170
+Horse-Power Six-Cylinder Engine. Below, Side View of Sunbeam 350
+Horse-Power Twelve-Cylinder Vee Engine.]
+
+The modern Sunbeam engines operate with a mean effective pressure of 135
+pounds with a compression ratio of 6 to 1 sea level. The connecting rods
+are of the articulated type as in the Renault motor and are very short.
+The weight of these motors turns out at 2.6 pounds per brake
+horse-power, and they are able to go through a 100 hour test without any
+trouble of any kind. The lubricating system comprises a dry base and oil
+pump for drawing the oil off from the base, whence it is delivered to
+the filter and cooling system. It then is pumped by a separate high
+pressure gear pump through the entire motor. In these larger European
+motors, castor-oil is used largely for lubrication. It is said that
+without the use of castor-oil it is impossible to hold full power for
+five hours. Coatalen favors aluminum cylinders rather than cast iron.
+The series of views in Figs. 247 to 250 inclusive, illustrates the
+vertical, narrow type of engine; the V-form; and the broad arrow type
+wherein three rows, each of six-cylinders, are set on a common
+crank-case. In this water-cooled series the gasoline and oil consumption
+are notably low, as is the weight per horse-power.
+
+[Illustration: Fig. 248.--Side View of Eighteen-Cylinder Sunbeam
+Coatalen Aircraft Engine Rated at 475 B.H.P.]
+
+[Illustration: Fig. 249.--Sunbeam Eighteen-Cylinder Motor, Viewed from
+Pump and Magneto End.]
+
+In the eighteen-cylinder overhead valve Sunbeam-Coatalen aircraft engine
+of 475 brake horse-power, there are no fewer than half a dozen magnetos.
+Each magneto is inclosed. Two sparks are furnished to each cylinder
+from independent magnetos. On this engine there are also no fewer than
+six carburetors. Shortness of crank-shaft, and therefore of engine
+length, and absence of vibration are achieved by the linking of the
+connecting-rods. Those concerned with three-cylinders in the broad arrow
+formation work on one crank-pin, the outer rods being linked to the
+central master one. In consequence of this arrangement, the piston
+travel in the case of the central row of cylinders is 160 mm., while the
+stroke of the pistons of the cylinders set on either side is in each
+case 168 mm. Inasmuch as each set of six-cylinders is completely
+balanced in itself, this difference in stroke does not affect the
+balance of the engine as a whole. The duplicate ignition scheme also
+applies to the twelve-cylinder 350 brake horse-power Sunbeam-Coatalen
+overhead valve aircraft engine type. It is distinguishable,
+incidentally, by the passage formed through the center of each induction
+pipe for the sparking plug in the center cylinder of each block of
+three. In this, as in the eighteen-cylinder and the six-cylinder types,
+there are two cam-shafts for each set of cylinders. These cam-shafts are
+lubricated by low pressure and are operated through a train of inclosed
+spur wheels at the magneto end of the machine. The six-cylinder, 170
+brake horse-power vertical type employs the same general principles,
+including the detail that each carburetor serves gas to a group of
+three-cylinders only. It will be observed that this engine presents
+notably little head resistance, being suitable for multi-engined
+aircraft.
+
+[Illustration: Fig. 250.--Propeller End of Sunbeam Eighteen-Cylinder 475
+B.H.P. Aviation Engine.]
+
+
+INDICATING METERS FOR AUXILIARY SYSTEMS
+
+[Illustration: Fig. 251.--View of Airplane Cowl Board, Showing the
+Various Navigating and Indicating Instruments to Aid the Aviator in
+Flight.]
+
+The proper functioning of the power plant and the various groups
+comprising it may be readily ascertained at any time by the pilot
+because various indicating meters and pressure gauges are provided which
+are located on a dash or cowl board in front of the aviator, as shown at
+Fig. 251. The speed indicator corresponds to the speedometer of an
+automobile and gives an indication of the speed the airplane is making,
+which taken in conjunction with the clock will make it possible to
+determine the distance covered at a flight. The altimeter, which is an
+aneroid barometer, outlines with fair accuracy the height above the
+ground at which a plane is flying. These instruments are furnished to
+enable the aviator to navigate the airplane when in the air, and if the
+machine is to be used for cross-country flying, they may be supplemented
+by a compass and a drift set. It will be evident that these are purely
+navigating instruments and only indicate the motor condition in an
+indirect manner. The best way of keeping track of the motor action is to
+watch the tachometer or revolution counter which is driven from the
+engine by a flexible shaft. This indicates directly the number of
+revolutions the engine is making per minute and, of course, any slowing
+up of the engine in normal flights indicates that something is not
+functioning as it should. The tachometer operates on the same principle
+as the speed indicating device or speedometer used in automobiles except
+that the dial is calibrated to show revolutions per minute instead of
+miles per hour. At the extreme right of the dash at Fig. 251 the spark
+advance and throttle control levers are placed. These, of course,
+regulate the motor speed just as they do in an automobile. Next to the
+engine speed regulating levers is placed a push button cut-out switch to
+cut out the ignition and stop the motor. Three pressure gauges are
+placed in a line. The one at the extreme right indicates the pressure of
+air on the fuel when a pressure feed system is used. The middle one
+shows oil pressure, while that nearest the center of the dash board is
+employed to show the air pressure available in the air starting system.
+It will be evident that the character of the indicating instruments will
+vary with the design of the airplane. If it was provided with an
+electrical starter instead of an air system electrical indicating
+instruments would have to be provided.
+
+
+COMPRESSED AIR-STARTING SYSTEMS
+
+Two forms of air-starting systems are in general use, one in which the
+crank-shaft is turned by means of an air motor, the other class where
+compressed air is admitted to the cylinders proper and the motor turned
+over because of the air pressure acting on the engine pistons. A system
+known as the "Never-Miss" utilizes a small double-cylinder air pump is
+driven from the engine by means of suitable gearing and supplies air to
+a substantial container located at some convenient point in the
+fuselage. The air is piped from the container to a dash-control valve
+and from this member to a peculiar form of air motor mounted near the
+crank-shaft. The air motor consists of a piston to which a rack is
+fastened which engages a gear mounted on the crank shaft provided with
+some form of ratchet clutch to permit it to revolve only in one
+direction, and then only when the gear is turning faster than the engine
+crank-shaft.
+
+The method of operation is extremely simple, the dash-control valve
+admitting air from the supply tank to the top of the pump cylinder. When
+in the position shown in cut the air pressure will force the piston and
+rack down and set the engine in motion. A variety of air motors are used
+and in some the pump and motor may be the same device, means being
+provided to change the pump to an air motor when the engine is to be
+turned over.
+
+The "Christensen" air starting system is shown at Figs. 252 and 253. An
+air pump is driven by the engine, and this supplies air to an air
+reservoir or container attached to the fuselage. This container
+communicates with the top of an air distributor when a suitable control
+valve is open. An air pressure gauge is provided to enable one to
+ascertain the air pressure available. The top of each cylinder is
+provided with a check valve, through which air can flow only in one
+direction, i.e., from the tank to the interior of the cylinder. Under
+explosive pressure these check valves close. The function of the
+distributor is practically the same as that of an ignition timer, its
+purpose being to distribute the air to the cylinders of the engine only
+in the proper firing order. All the while that the engine is running and
+the car is in motion the air pump is functioning, unless thrown out of
+action by an easily manipulated automatic control. When it is desired to
+start the engine a starting valve is opened which permits the air to
+flow to the top of the distributor, and then through a pipe to the check
+valve on top of the cylinder about to explode. As the air is going
+through under considerable pressure it will move the piston down just as
+the explosion would, and start the engine rotating. The inside of the
+distributor rotates and directs a charge of air to the cylinder next to
+fire. In this way the engine is given a number of revolutions, and
+finally a charge of gas will be ignited and the engine start off on its
+cycle of operation. To make starting positive and easier some gasoline
+is injected in with the air so an inflammable mixture is present in the
+cylinders instead of air only. This ignites easily and the engine starts
+off sooner than would otherwise be the case. The air pressure required
+varies from 125 to 250 pounds per square inch, depending upon the size
+and type of the engine to be set in motion.
+
+[Illustration: Fig. 252.--Parts of Christensen Air Starting System Shown
+at A, and Application of Piping and Check Valves to Cylinders of
+Thomas-Morse Aeromotor Outlined at B.]
+
+[Illustration: Fig. 253.--Diagrams Showing Installation of Air Starting
+System on Thomas-Morse Aviation Motor.]
+
+
+ELECTRIC STARTING SYSTEMS
+
+Starters utilizing electric motors to turn over the engine have been
+recently developed, and when properly made and maintained in an
+efficient condition they answer all the requirements of an ideal
+starting device. The capacity is very high, as the motor may draw
+current from a storage battery and keep the engine turning over for
+considerable time on a charge. The objection against their use is that
+it requires considerable complicated and costly apparatus which is
+difficult to understand and which requires the services of an expert
+electrician to repair should it get out of order, though if battery
+ignition is used the generator takes the place of the usual ignition
+magneto.
+
+In the Delco system the electric current is generated by a combined
+motor-generator permanently geared to the engine. When the motor is
+running it turns the armature and the motor generator is acting as a
+dynamo, only supplying current to a storage battery. On account of the
+varying speeds of the generator, which are due to the fluctuation in
+engine speed, some form of automatic switch which will disconnect the
+generator from the battery at such times that the motor speed is not
+sufficiently high to generate a current stronger than that delivered by
+the battery is needed. These automatic switches are the only delicate
+part of the entire apparatus, and while they require very delicate
+adjustment they seem to perform very satisfactorily in practice.
+
+When it is desired to start the engine an electrical connection is
+established between the storage battery and the motor-generator unit,
+and this acts as a motor and turns the engine over by suitable gearing
+which engages the gear teeth cut into a special gear or disc attached to
+the engine crank-shaft. When the motor-generator furnishes current for
+ignition as well as for starting the motor, the fact that the current
+can be used for this work as well as starting justifies to a certain
+extent the rather complicated mechanism which forms a complete starting
+and ignition system, and which may also be used for lighting if
+necessary in night flying.
+
+An electric generator and motor do not complete a self-starting system,
+because some reservoir or container for electric current must be
+provided. The current from the generator is usually stored in a storage
+battery from which it can be made to return to the motor or to the same
+armature that produced it. The fundamental units of a self-starting
+system, therefore, are a generator to produce the electricity, a storage
+battery to serve as a reservoir, and an electric motor to rotate the
+motor crank-shaft. Generators are usually driven by enclosed gearing,
+though silent chains are used where the center distance between the
+motor shaft and generator shaft is too great for the gears. An electric
+starter may be directly connected to the gasoline engine, as is the case
+where the combined motor-generator replaces the fly-wheel in an
+automobile engine. The motor may also drive the engine by means of a
+silent chain or by direct gear reduction.
+
+Every electric starter must use a switch of some kind for starting
+purposes and most systems include an output regulator and a reverse
+current cut-out. The output regulator is a simple device that regulates
+the strength of the generator current that is supplied the storage
+battery. A reverse current cut-out is a form of check valve that
+prevents the storage battery from discharging through the generator.
+Brief mention is made of electric starting because such systems will
+undoubtedly be incorporated in some future airplane designs. Battery
+ignition is already being experimented with.
+
+
+BATTERY IGNITION SYSTEM PARTS
+
+A battery ignition system in its simplest form consists of a current
+producer, usually a set of dry cells or a storage battery, an induction
+coil to transform the low tension current to one having sufficient
+strength to jump the air gap at the spark-plug, an igniter member
+placed in the combustion chamber and a timer or mechanical switch
+operated by the engine so that the circuit will be closed only when it
+is desired to have a spark take place in the cylinders. Battery ignition
+systems may be of two forms, those in which the battery current is
+stepped up or intensified to enable it to jump an air gap between the
+points of the spark plug, these being called "high tension" systems and
+the low tension form (never used on airplane motors) in which the
+battery current is not intensified to a great degree and a spark
+produced in the cylinder by the action of a mechanical circuit breaker
+in the combustion chamber. The low tension system is the simplest
+electrically but the more complex mechanically. The high tension system
+has the fewest moving parts but numerous electrical devices. At the
+present time all airplane engines use high tension ignition systems, the
+magneto being the most popular at the present time. The current
+distribution and timing devices used with modern battery systems are
+practically the same as similar parts of a magneto.
+
+
+
+
+INDEX
+
+
+                                                          PAGE
+
+  A
+
+  Action of Four-cycle Engine                               38
+  Action of Le Rhone Rotary Engine                         503
+  Action of Two-cycle Engine                                41
+  Action of Vacuum Feed System                             119
+  Actual Duration of Different Functions                    93
+  Actual Heat Efficiency                                    62
+  Adiabatic Diagram                                         51
+  Adiabatic Law                                             50
+  Adjustment of Bearings                                   449
+  Adjustment of Carburetors                                151
+  Aerial Motors, Must be Light                              20
+  Aerial Motors, Operating Conditions of                    19
+  Aerial Motors, Requirements of                            19
+  Aeromarine Six-cylinder Engine                           527
+  Aeronautics, Division in Branches                         18
+  Aerostatics                                               18
+  Air-cooled Engine Design                                 229
+  Air-cooling Advantages                                   231
+  Air-cooling, Direct Method                               228
+  Air-cooling Disadvantages                                231
+  Air-cooling Systems                                      223
+  Aircraft, Heavier Than Air                                17
+  Aircraft, Lighter Than Air                                18
+  Aircraft Types, Brief Consideration of                    17
+  Air Needed to Burn Gasoline                              113
+  Airplane Engine, Power Needed                             21
+  Airplane Engines, Overhauling                            412
+  Airplane Engine, How to Time                             269
+  Airplane Engine Lubrication                              209
+  Airplane, How Supported                                   21
+  Airplane Motors, German                                  543
+  Airplane Motor Types                                      20
+  Airplane Motors, Weight of                                21
+  Airplane Power Plant Installation                        324
+  Airplane Types                                            18
+  Airplanes, Horse-power Used in                            26
+  Air Pressure Diminution, With Altitude                   144
+  Altitude, How it Affects Mixture                         153
+  Aluminum, Use in Pistons                                 297
+  American Aviation Engines, Statistics                    546
+  Anzani Radial Engine Installation                        344
+  Anzani Six-cylinder Star Engine                          465
+  Anzani Six-cylinder Water-cooled Engine                  459
+  Anzani Ten- and Twenty-cylinder Engines                  468
+  Anzani Three-cylinder Engine                             459
+  Anzani Three-cylinder Y Type                             462
+  Argus Engine Construction                                545
+  Armature Windings                                        168
+  Atmospheric Conditions, Compensating For                 143
+  Austro-Daimler Engine                                    557
+  Aviatics                                                  18
+  Aviation Engine, Aeromarine                              527
+  Aviation Engine, Anzani Six-cylinder Star                465
+  Aviation Engine, Canton and Unne                         469
+  Aviation Engine Cooling                                  219
+  Aviation Engine, Curtiss                                 519
+  Aviation Engine Cylinders                                233
+  Aviation Engine, Early Gnome                             472
+  Aviation Engine, German Gnome Type                       495
+  Aviation Engine, Gnome Monosoupape                       486
+  Aviation Engine, How To Dismantle                        415
+  Aviation Engine, How to Start                            460
+  Aviation Engine, Le Rhone Rotary                         495
+  Aviation Engine Oiling                                   218
+  Aviation Engine Parts, Functions of                       82
+  Aviation Engine, Renault Air-cooled                      507
+  Aviation Engine, Stand for Supporting                    414
+  Aviation Engine, Sturtevant                              515
+  Aviation Engine, Thomas-Morse                            521
+  Aviation Engine Types                                    457
+  Aviation Engine, Wisconsin                               531
+  Aviation Engines, Anzani Six-cylinder Water-cooled       459
+  Aviation Engines, Anzani Ten- and Twenty-cylinder        468
+  Aviation Engines, Anzani Three-cylinder                  459
+  Aviation Engines, Anzani Y Type                          462
+  Aviation Engines, Argus                                  545
+  Aviation Engines, Austro-Daimler                         557
+  Aviation Engines, Benz                                   551
+  Aviation Engines, Four- and Six-cylinder                  88
+  Aviation Engines, German                                 543
+  Aviation Engines, Hall-Scott                             539
+  Aviation Engines, Hispano-Suiza                          512
+  Aviation Engines, Mercedes                               543
+  Aviation Engines, Overhauling                            412
+  Aviation Engines, Principal Parts of                      80
+  Aviation Engines, Starting Systems For                   567
+  Aviation Engines, Sunbeam                                558
+
+  B
+
+  Balanced Crank-shafts                                    318
+  Ball-bearing Crank-shafts                                319
+  Battery Ignition Systems                                 571
+  Baverey Compound Nozzle                                  137
+  Bearings, Adjustment of                                  449
+  Bearing Alignment                                        453
+  Bearing Brasses, Fitting                                 450
+  Bearing Parallelism, Testing                             453
+  Bearing Scrapers and Their Use                           446
+  Benz Aviation Engines                                    551
+  Benz Engine Statistics                                   551
+  Berling Magneto                                          174
+  Berling Magneto, Adjustment of                           180
+  Berling Magneto Care                                     180
+  Berling Magneto Circuits                                 176
+  Berling Magneto, Setting                                 178
+  Block Castings                                           234
+  Blowing Back                                             269
+  Bolts, Screwing Down                                     452
+  Bore and Stroke Ratio                                    240
+  Boyle's Law                                               49
+  Brayton Engine                                            48
+  Breaker Box, Adjustment of                               180
+  Breast and Hand Drills                                   387
+  Burning Out Carbon Deposits                              421
+  Bushings, Cam-shaft, Wear in                             456
+
+  C
+
+  Calipers, Inside and Outside                             398
+  Cam Followers, Types of                                  260
+  Cams for Valve Actuation                                 259
+  Cam-shaft Bushings                                       456
+  Cam-shaft Design                                         313
+  Cam-shaft Drive Methods                                  261
+  Cam-shaft Testing                                        451
+  Cam-shafts and Timing Gears                              456
+  Canton and Unne Engine                                   469
+  Carbon, Burning out with Oxygen                          421
+  Carbon Deposits, Cause of                                418
+  Carbon Removal                                           419
+  Carbon Scrapers, How Used                                420
+  Carburetion Principles                                   112
+  Carburetion System Troubles                              355
+  Carburetor, Claudel                                      127
+  Carburetor, Compound Nozzle Zenith                       135
+  Carburetor, Concentric Float and Jet Type                125
+  Carburetor, Duplex Zenith                                138
+  Carburetor, Duplex Zenith, Trouble in                    357
+  Carburetor Installation, In Airplanes                    148
+  Carburetor, Le Rhone                                     501
+  Carburetor, Master Multiple Jet                          133
+  Carburetor, Schebler                                     125
+  Carburetor Troubles, How to Locate                       354
+  Carburetor, Two Stage                                    131
+  Carburetor, What it Should Do                            114
+  Carburetors, Float Feed                                  122
+  Carburetors, Multiple Nozzle                             130
+  Carburetors, Notes on Adjustment                         151
+  Carburetors, Reversing Position of                       149
+  Carburetors, Spraying                                    120
+  Care of Dixie Magneto                                    188
+  Castor Oil, for Cylinder Lubrication                     205
+  Castor Oil, Why Used In Gnome Engines                    211
+  Center Gauge                                             403
+  Chisels, Forms of                                        384
+  Christensen Air Starting System                          567
+  Circuits, Magnetic                                       161
+  Classification of Engines                                458
+  Claudel Carburetor                                       127
+  Cleaning Distributor                                     180
+  Clearances Between Valve Stem and Actuators              261
+  Combustion Chamber Design                                239
+  Combustion Chambers, Spherical                            76
+  Common Tools, Outfit of                                  378
+  Comparing Two-cycle and Four-cycle Types                  44
+  Compound Cam Followers                                   260
+  Compound Piston Rings                                    301
+  Compressed Air Starting System                           565
+  Compression, Factors Limiting                             69
+  Compression, in Explosive Motors, Value of                68
+  Compression Pressures, Chart for                          72
+  Compression Temperature                                   71
+  Computations for Horse-power Needed                       25
+  Computations for Temperature                              52
+  Concentric Piston Ring                                   299
+  Concentric Valves                                        255
+  Connecting Rod Alignment, Testing                        454
+  Connecting Rod, Conventional                             308
+  Connecting Rod Forms                                     305
+  Connecting Rod, Gnome Engine                             305
+  Connecting Rods, Fitting                                 449
+  Connecting Rods for Vee Engines                          310
+  Connecting Rods, Le Rhone                                498
+  Connecting Rods, Master                                  310
+  Constant Level Splash System                             215
+  Construction of Dixie Magneto                            186
+  Construction of Pistons                                  288
+  Conversion of Heat to Power                               58
+  Cooling by Air                                           223
+  Cooling by Positive Water Circulation                    224
+  Cooling, Heat Loss in                                     66
+  Cooling System Defects                                   358
+  Cooling Systems Used                                     223
+  Cooling Systems, Why Needed                              219
+  Cotter Pin Pliers                                        384
+  Crank-case, Conventional                                 320
+  Crank-case Forms                                         320
+  Crank-case, Gnome                                        323
+  Crank-shaft, Built Up                                    315
+  Crank-shaft Construction                                 315
+  Crank-shaft Design                                       315
+  Crank-shaft Equalizer                                    449
+  Crank-shaft Form                                         315
+  Crank-shaft, Gnome Engine                                483
+  Crank-shafts, Balanced                                   318
+  Crank-shafts, Ball Bearing                               319
+  Cross Level                                              403
+  Crude Petroleum, Distillates of                          111
+  Curtiss Aviation Engines                                 519
+  Curtiss Engine Installation                              328
+  Curtiss Engine Repairing Tools                           408
+  Cutting Oil Grooves                                      448
+  Cylinder Blocks, Advantages of                           237
+  Cylinder Block, Duesenberg                               235
+  Cylinder Castings, Individual                            234
+  Cylinder Construction                                    233
+  Cylinder Faults and Correction                           416
+  Cylinder Form and Crank-shaft Design                     238
+  Cylinder Head Packings                                   417
+  Cylinder Head, Removable                                 239
+  Cylinder, I Head Form                                    248
+  Cylinder, L Head Form                                    248
+  Cylinder Oils                                            206
+  Cylinder Placing                                          20
+  Cylinder Placing in V Motor                               99
+  Cylinder Retention, Gnome                                475
+  Cylinder, T Head Form                                    248
+  Cylinders, Cast in Blocks                                235
+  Cylinders, Odd Number in Rotary Engines                  482
+  Cylinders, Repairing Scored                              423
+  Cylinders, Valve Location in                             245
+
+  D
+
+  Defects in Cylinders                                     417
+  Defects in Dry Battery                                   373
+  Defects in Fuel System                                   354
+  Defects in Induction Coil                                373
+  Defects in Magneto                                       372
+  Defects in Storage Battery                               372
+  Defects in Timer                                         373
+  Defects in Wiring and Remedies                           373
+  Die Holder                                               394
+  Dies for Thread Cutting                                  395
+  Diesel Motor Cards                                        67
+  Diesel System                                            144
+  Direct Air Cooling                                       228
+  Dirigible Balloons                                        18
+  Dismantling Airplane Engine                              415
+  Distillates of Crude Petroleum                           111
+  Division of Circle in Degrees                            268
+  Dixie Ignition Magneto                                   184
+  Dixie Magneto, Care of                                   188
+  Draining Oil From Crank-case                             214
+  Drilling Machines                                        386
+  Drills, Types and Use                                    388
+  Driving Cam-shaft, Methods of                            262
+  Dry Cell Battery, Defects in                             373
+  Duesenberg Sixteen Valve Engine                          525
+  Duesenberg Valve Action                                  255
+  Duplex Zenith Carburetor                                 138
+
+  E
+
+  Early Gnome Motor, Construction of                       472
+  Early Ignition Systems                                   155
+  Early Types of Gas Engine                                 28
+  Early Vaporizer Forms                                    120
+  Eccentric Piston Ring                                    299
+  Economy, Factors Governing                                64
+  Efficiency, Actual Heat                                   62
+  Efficiency, Maximum Theoretical                           61
+  Efficiency, Mechanical                                    62
+  Efficiency of Internal Combustion Engine                  60
+  Efficiency, Various Measures of                           61
+  Eight-cylinder Engine                                     95
+  Eight-cylinder Timing Diagram                            276
+  Electricity and Magnetism, Relation of                   162
+  Electrical Ignition Best                                 156
+  Electric Starting Systems                                569
+  Engine, Advantages of V Type                              95
+  Engine Base Construction                                 319
+  Engine Bearings, Adjusting                               443
+  Engine Bearings, Refitting                               442
+  Engine Bed Timbers, Standard                             330
+  Engine, Four-cycle, Action of                             38
+  Engine, Four-cycle, Piston Movements in                   40
+  Engine Functions, Duration of                             93
+  Engine Ignition, Locating Troubles                       353
+  Engine Installation, Gnome                               344
+  Engine Installation, Anzani Radial                       344
+  Engine Installation, Hall-Scott                          332
+  Engine Installation, Rotary                              342
+  Engine Operation, Sequence of                             84
+  Engine Parts and Functions                                80
+  Engine Starts Hard, Ignition Troubles Causing            369
+  Engine Stoppage, Causes of                               347
+  Engine Temperatures                                      221
+  Engine Trouble Charts                                    369
+  Engine Troubles, Cooling                                 358
+  Engine Troubles, Hints For Locating                      345
+  Engine Troubles, Ignition                                353
+  Engine Troubles, Noisy Operation                         359
+  Engine Troubles, Oiling                                  357
+  Engine Troubles Summarized                               350
+  Engine, Two-cycle, Action of                              41
+  Engines, Classification of                               458
+  Engines, Cylinder Arrangement                          31-32
+  Engines, Eight-cylinder V                                 95
+  Engines, Four-cylinder Forms                              88
+  Engines, Graphic Comparison of                      33-34-35
+  Engines, Internal Combustion, Types of                    30
+  Engines, Multiple Cylinder, Power Delivery in             91
+  Engines, Multiple Cylinder, Why Best                      83
+  Engines, Rotary Cylinder                                 107
+  Engines, Six-cylinder Forms                               88
+  Engines, Twelve-cylinder                                  96
+  Equalizer, Crank-shaft                                   449
+  Exhaust Closing                                          270
+  Exhaust Valve Design, Early Gnome                        475
+  Exhaust Valve Opening                                    270
+  Explosive Gases, Mixtures of                              56
+  Explosive Motors, Inefficiency in                         74
+  Explosive Motors, Why Best                                27
+
+  F
+
+  Factors Governing Economy                                 64
+  Factors Limiting Compression                              70
+  Faults in Ignition                                       352
+  Figuring Horse-power Needed                               21
+  Files, Use and Care of                                   383
+  First Law of Gases                                        49
+  Fitting Bearings By Scraping                             447
+  Fitting Brasses                                          450
+  Fitting Connecting Rods                                  449
+  Fitting Main Bearings                                    448
+  Fitting Piston Rings                                     439
+  Float Feed Carburetor Development                        124
+  Float Feed Carburetors                                   122
+  Force Feed Oiling System                                 218
+  Forked Connecting Rods                                   310
+  Four-cycle Engine, Action of                              38
+  Four-cycle Engine, Why Best                               45
+  Fourteen-cylinder Engine                                 474
+  Four Valves Per Cylinder                                 284
+  Friction, Definition of                                  302
+  Fuel Feed By Gravity                                     116
+  Fuel Feed by Vacuum Tank                                 117
+  Fuel Storage and Supply                                  116
+  Fuel Strainers, Types of                                 141
+  Fuel Strainers, Utility of                               140
+  Fuel System Faults                                       354
+  Fuel System Installation, Hall-Scott                     336
+  Fuel System, Gnome                                       490
+  Fuel Utilization Chart                                    62
+
+  G
+
+  Gas Engine, Beau de Rocha's Principles                    59
+  Gas Engine Development                                    28
+  Gas Engine, Early Forms of                                48
+  Gas Engine, Inventors of                                  29
+  Gas Engine, Theory of                                     47
+  Gases, Compression of                                     49
+  Gases, First Law of                                       49
+  Gases, Second Law of                                      50
+  Gaskets, How to Use                                      452
+  Gasoline, Air Needed to Burn                             113
+  Gas Engines, Parts of                                     80
+  Gas Vacuum Engine, Brown's                                28
+  German Airplane Motors                                   543
+  German Gnome Type Engine                                 495
+  Gnome Aviation Engine, Early Form                        472
+  Gnome Crank-shaft                                        483
+  Gnome Cylinder, Machining                                489
+  Gnome Cylinder Retention                                 475
+  Gnome Engine, Fuel, Lubrication and Ignition             490
+  Gnome Engine, German Type                                495
+  Gnome Engine Installation                                344
+  Gnome Firing Order                                       482
+  Gnome Fourteen-cylinder, Engine                          474
+  Gnome Fourteen-cylinder Engine Details                   480
+  Gnome Monosoupape, How to Time                           278
+  Gnome Monosoupape Type Engine                            486
+  Graphic Comparison of Engine Types                  33-34-35
+  Graphic Comparison, Two- and Four-cycle                   46
+  Gravity Feed System                                      116
+  Grinding Valves                                          429
+
+  H
+
+  Hall-Scott Aviation Engines                              539
+  Hall-Scott Engine Installation                           332
+  Hall-Scott Engine, Preparations For Starting             341
+  Hall-Scott Engine Tools                                  410
+  Hall-Scott Lubrication System                            211
+  Hall-Scott Statistic Sheet                               544
+  Heat and Its Work                                         54
+  Heat in Gas Engine Cylinder                               69
+  Heat Given to Cooling Water                               78
+  Heat Loss, Causes of                                      74
+  Heat Loss in Airplane Engine                             221
+  Heat Loss in Wall Cooling                                 65
+  High Altitude, How it Affects Power                      144
+  High Tension Magneto                                     172
+  Hints For Locating Engine Troubles                       345
+  Hints for Starting Engine                                361
+  Hispano-Suiza Model A Engine                             512
+  Horse-power Needed in Airplane                            21
+  Horse-power Needed, How Figured                           22
+  How An Engine is Timed                                   277
+
+  I
+
+  Ignition, Electric                                       156
+  Ignition, Elements of                                    157
+  Ignition of Gnome Engine                                 490
+  Ignition System, Battery                                 571
+  Ignition Systems, Early                                  155
+  Ignition System Faults                                   352
+  Ignition, Time of                                        273
+  Ignition, Two Spark                                      196
+  I Head Cylinders                                         248
+  Improvements in Gas Engines                               29
+  Indicating Meters, Engine Speed                          563
+  Indicating Meters, Oil and Air Pressure                  563
+  Indicator Cards, How To Read                              66
+  Indicator Cards, Value of                                 66
+  Individual Cylinder Castings                             234
+  Induction Coil, Defects in                               373
+  Inefficiency, Causes of                                   74
+  Inlet Valve Closing                                      272
+  Inlet Valve Opening                                      270
+  Installation, Airplane Engine                            324
+  Installation, Curtiss OX-2 Engine                        328
+  Installation, Hall-Scott Engine                          332
+  Installation of Rotary Engines                           342
+  Intake Manifold Construction                             143
+  Intake Manifold Design                                   142
+  Internal Combustion Engine, Efficiency of             60, 62
+  Internal Combustion Engines, Main Types of                30
+  Inverted Engine Placing                                  325
+  Isothermal Diagram                                        51
+  Isothermal Law                                            48
+
+  K
+
+  Keeping Oil Out of Combustion Chamber                    303
+  Knight Sleeve Valves                                     266
+
+  L
+
+  Lag and Lead, Explanation of                             268
+  Lapping Crank-pins                                       445
+  Lead Given Exhaust Valve                                 270
+  Leak Proof Piston Rings                                  301
+  Lenoir Engine Action                                      48
+  Le Rhone Cams and Valve Actuation                        500
+  Le Rhone Carburetor                                      501
+  Le Rhone Connecting Rod Assembly, Distinctive            498
+  Le Rhone Engine Action                                   503
+  Le Rhone Rotary Engine                                   495
+  L Head Cylinders                                         248
+  Liquid Fuels, Properties of                              110
+  Locating Carburetor Troubles                             354
+  Locating Engine Troubles                                 350
+  Locating Ignition Troubles                               353
+  Locating Oiling Troubles                                 357
+  Location of Magneto Trouble                              181
+  Losses in Wall Cooling                                    65
+  Lost Power and Overheating, Summary of Troubles Causing  363
+  Lubricants, Derivation of                                204
+  Lubricants, Requirements of                              204
+  Lubricating System Classification                        208
+  Lubricating Systems, Selection of                        208
+  Lubrication By Constant Level Splash System              215
+  Lubrication By Dry Crank-case Method                     218
+  Lubrication By Force Feed Best                           218
+  Lubrication of Magneto                                   180
+  Lubrication System, Gnome                                490
+  Lubrication System, Hall-Scott                           211
+  Lubrication System, Thomas-Morse                         210
+  Lubrication, Theory of                                   202
+  Lubrication, Why Necessary                               201
+
+  M
+
+  Magnetic Circuits                                        161
+  Magnetic Influence Defined                               158
+  Magnetic Lines of Force                                  161
+  Magnetic Substances                                      158
+  Magnetism, Flow Through Armature                         166
+  Magnetism, Fundamentals of                               157
+  Magnetism, Relation to Electricity                       162
+  Magneto, Action of High Tension                          173
+  Magneto Armature Windings                                168
+  Magneto, Basic Principles of                             163
+  Magneto, Berling                                         174
+  Magneto, Defects in                                      372
+  Magneto Distributor, Cleaning                            180
+  Magneto Ignition Systems                                 169
+  Magneto Ignition Wiring                                  179
+  Magneto Interrupter, Adjustment of                       180
+  Magneto, Low Voltage                                     168
+  Magneto, Lubrication of                                  180
+  Magneto Maintenance                                      180
+  Magneto, Method of Driving                               175
+  Magneto Parts and Functions                              167
+  Magneto, The Dixie                                       184
+  Magneto Timing                                           179
+  Magneto, Timing Dixie                                    188
+  Magneto, Transformer System                              171
+  Magneto Trouble, Location of                             181
+  Magneto, True High Tension                               172
+  Magneto, Two Spark Dual                                  177
+  Magnets, Forms of                                        160
+  Magnets, How Produced                                    162
+  Magnets, Properties of                                   159
+  Main Bearings, Fitting                                   448
+  Manifold, Intake                                         143
+  Master Multiple Jet Carburetor                           133
+  Master Rod Construction                                  310
+  Maximum Theoretical Efficiency                            61
+  Meaning of Piston Speed                                  241
+  Measures of Efficiency                                    61
+  Measuring Tools                                          397
+  Mechanical Efficiency                                     62
+  Mercedes Aviation Engine                                 543
+  Metering Pin Carburetor, Stewart                         128
+  Micrometer Caliper, Beading                              405
+  Micrometer Calipers, Types and Use                       404
+  Mixture, Effect of Altitude on                           153
+  Mixture, Proportions of                                  151
+  Mixture, Starvation of                                   149
+  Monosoupape Gnome Engine                                 486
+  Mother Bod, Gnome Engine                                 305
+  Motor Misfires, Carburetor Faults Causing                374
+  Motor Misfires, Ignition Troubles Causing                370
+  Motor Races, Carburetor Faults Causing                   374
+  Motor Starts Hard, Carburetor Faults Causing             374
+  Motor Stops In Flight, Carburetor Faults                 374
+  Motor Stops Without Warning, Ignition Troubles           370
+  Multiple Cylinder Engine, Why Best                        83
+  Multiple Nozzle Vaporizers                               129
+  Multiple Valve Advantages                                286
+
+  N
+
+  Noisy Engine Operation, Causes of                        359
+  Noisy Operation, Carburetor Faults Causing               374
+  Noisy Operation, Summary of Troubles Causing             365
+
+  O
+
+  Offset Cylinders, Reason for                             243
+  Oil Bi-pass, Function of                                 213
+  Oil, Draining From Crank-case                            214
+  Oil Grooves, Cutting                                     448
+  Oil Pressure in Hall-Scott System                        214
+  Oil Pressure Relief Bi-pass                              213
+  Oiling System Defects                                    357
+  Oils for Cylinder Lubrication                            206
+  Oils for Hall-Scott Engine                               215
+  Oils for Lubrication                                     204
+  Operating Principles of Engines                           37
+  Oscillating Piston Pin                                   295
+  Otto Four-cycle Cards                                     67
+  Overhauling Aviation Engines                             412
+  Overhead Cam-shaft Location                              252
+  Overheating, Causes of                                   359
+
+  P
+
+  Panhard Concentric Valves                                255
+  Petroleum, Distillates of                                111
+  Piston, Differential                                     291
+  Piston Pin Retention                                     293
+  Piston Ring Construction                                 298
+  Piston Ring Joints                                       299
+  Piston Ring Manipulation                                 438
+  Piston Ring Troubles                                     437
+  Piston Rings, Compound                                   301
+  Piston Rings, Concentric                                 299
+  Piston Rings, Eccentric                                  299
+  Piston Rings, Fitting                                    439
+  Piston Rings, Leak Proof                                 301
+  Piston Rings, Replacing                                  441
+  Piston Speed in Airplane Engines                         241
+  Piston Speed, Meaning of                                 241
+  Piston Troubles and Remedies                             436
+  Pistons, Aluminum                                        296
+  Pistons, Details of                                      288
+  Pistons for Two-cycle Engines                            289
+  Positive Valve Systems                                   283
+  Power, Affected by High Altitude                         145
+  Power Delivery in Multiple Cylinder Engines               91
+  Power, How Obtained From Heat                             58
+  Power Needed in Airplane Engines                          21
+  Power Used in Airplanes                                   26
+  Precautions in Assembling Parts                          452
+  Pressure Relief Fitting                                  213
+  Pressures and Temperatures                                63
+  Principles of Carburetion                                112
+  Principles of Magneto Action                             163
+  Properties of Cylinder Oils                              207
+  Properties of Liquid Fuels                               110
+  Pump Circulation Systems                                 226
+  Pump Forms                                               226
+
+  R
+
+  Radial Cylinder Arrangement                              103
+  Reading Indicator Cards                                   67
+  Reamers, Types and Use                                   392
+  Reassembling Parts, Precautions in                       451
+  Removable Cylinder Head                                  239
+  Renault Air Cooled Engine                                507
+  Renault Engine Details                                   508
+  Repairing Scored Cylinders                               423
+  Requisites for Best Power Effect                          59
+  Reseating and Truing Valves                              426
+  Resistance, Influence of                                  22
+  Rotary Cylinder Engines                                  107
+  Rotary Engine, Le Rhone                                  495
+  Rotary Engines, Castor Oil for                           211
+  Rotary Engines, Installing                               342
+  Rotary Engines, Why Odd Number of Cylinders              109
+  Rotary Engines, Why Odd Number of Cylinders Is Used      482
+
+  S
+
+  S. A. E. Engine Bed Dimensions                           330
+  Salmson Nine-cylinder Engine                             470
+  Schebler Carburetor                                      125
+  Scissors Joint Rods                                      310
+  Scored Cylinders, Repairing                              422
+  Scrapers, Types of Bearing                               446
+  Scraping Bearings to Fit                                 447
+  Second Law of Gases                                       50
+  Sequence of Engine Operation                              84
+  Six-cylinder Timing Diagram                              275
+  Sixteen Valve Duesenberg Engine                          525
+  Skipping or Irregular Operation, Causes of               367
+  Sliding Sleeve Valves                                    266
+  Spark Plug Air Gaps, Setting                             197
+  Spark Plug, Design of                                    193
+  Spark Plug, Mica                                         194
+  Spark Plug, Porcelain                                    193
+  Spark Plugs, Defects in                                  371
+  Spark Plugs for Two Spark Ignition                       197
+  Spark Plug, Special for Airplane Engine                  199
+  Spark Plug, Standard S. A. E.                            195
+  Spherical Combustion Chambers                             76
+  Splash Lubrication                                       215
+  Split Pin Remover                                        384
+  Spraying Carburetors                                     120
+  Springless Valves                                        280
+  Springs, for Valves                                      263
+  Spring Winder                                            384
+  Sprung Cam-shaft, Testing                                451
+  Stand for Supporting Engine                              414
+  Starting Engine, Hints for                               361
+  Starting Hall-Scott Engine                               341
+  Starting System, Christensen                             567
+  Starting Systems, Compressed Air                         565
+  Starting Systems, Electric                               569
+  Statistics, American Engines                        546, 547
+  Statistic Sheet, Hall-Scott Engines                      544
+  Statistics of Benz Engine                                551
+  Steam Engine, Efficiency of                               59
+  Steam Engine, Why Not Used                                27
+  Steel Scale, Machinists'                                 399
+  Stewart Metering Pin Carburetor                          128
+  Storage Battery, Defects in                              372
+  Stroke and Bore Ratio                                    240
+  Sturtevant Model 5A Engine                               515
+  Summary of Engine Types                                   30
+  Sunbeam Aviation Engines                                 588
+  Sunbeam Eighteen-Cylinder Engine                         561
+
+  T
+
+  Tap and Die Sets                                         397
+  Taps for Thread Cutting                                  394
+  Tee Head Cylinders                                       247
+  Temperature Computations                                  52
+  Temperatures and Explosive Pressures                      64
+  Temperatures and Pressures                                63
+  Temperatures, Operating                                  221
+  Testing Bearing Parallelism                              453
+  Testing Connecting Rod Alignment                         454
+  Testing Fit of Bearings                                  446
+  Testing Sprung Cam-shaft                                 451
+  Theory of Gas Engine                                      47
+  Theory of Lubrication                                    203
+  Thermo-syphon Cooling System                             227
+  Thomas-Morse Aviation Engine                             521
+  Thomas-Morse Lubrication System                          210
+  Thread Pitch Gauge                                       403
+  Time of Ignition                                         273
+  Timer, Defects in                                        373
+  Times of Explosion                                        56
+  Timing Dixie Magneto                                     188
+  Timing Gears, Effects of Wear                            456
+  Timing Magneto                                           179
+  Timing Valves                                            267
+  Tool Outfits, Typical                                    408
+  Tools for Adjusting and Erecting                         378
+  Tools for Bearing Work                                   445
+  Tools for Curtiss Engines                                408
+  Tools for Grinding Valves                                430
+  Tools for Hall-Scott Engines                        410, 411
+  Tools for Measuring                                      397
+  Tools for Reseating Valves                               426
+  Trouble in Carburetion System                            355
+  Trouble, Location of Magneto                             181
+  Troubles, Engine, How to Locate                          345
+  Troubles, Ignition                                       353
+  Troubles in Oiling System                                357
+  True High Tension Magneto                                172
+  Twelve-Cylinder Engines                                   96
+  Two-and Four-Cycle Types, Comparison of                   44
+  Two-Cycle Engine Action                                   41
+  Two-Cycle Three-Port Engine                               43
+  Two-Cycle Two-Port Engine                                 42
+  Two-Spark Ignition                                       196
+  Two-Stage Carburetor                                     131
+  Types of Aircraft                                         17
+  Types of Internal Combustion Engines                      30
+
+  V
+
+  Vacuum Fuel Feed, Stewart                                119
+  Value of Compression                                      69
+  Value of Indicator Cards                                  66
+  Valve Actuation, Le Rhone                                500
+  Valve Design and Construction                            256
+  Valve-Grinding Processes                                 429
+  Valve-Lifting Cams                                       259
+  Valve-Lifting Plungers                                   260
+  Valve Location Practice                                  245
+  Valve Operating Means                                    252
+  Valve Operating System, Depreciation in                  433
+  Valve Operation                                          258
+  Valve Removal and Inspection                             424
+  Valve Seating, How to Test                               432
+  Valve Springs                                            263
+  Valve Timing, Exhaust                                    270
+  Valve Timing, Gnome Monosoupape                          278
+  Valve Timing, Intake                                     270
+  Valve Timing, Lag and Lead                               269
+  Valve Timing Procedure                                   277
+  Valve Timing Practice                                    267
+  Valves, Electric Welded                                  258
+  Valves, Flat and Bevel Seat                              257
+  Valves, Four per Cylinder                                284
+  Valves, How Placed in Cylinder                           247
+  Valves in Cages                                          249
+  Valves in Removable Heads                                249
+  Valves, Materials Used for                               258
+  Valves, Reseating                                        426
+  Vaporizer, Simple Forms of                               120
+  V Engines, Cylinder Arrangement in                       102
+  Vernier, How Used                                        401
+
+  W
+
+  Wall Cooling, Losses in                                   65
+  Water Cooling by Natural Circulation                     227
+  Water Cooling System                                     224
+  Weight of Airplane Motors                                 21
+  Wiring, Defects in                                       373
+  Wiring Magneto Ignition System                           179
+  Wisconsin Engines                                        531
+  Wrenches, Forms of                                       380
+  Wrist-pin Retention                                      293
+  Wrist-pin Retention Locks                                295
+  Wrist-pin Wear and Remedy                                442
+
+  Z
+
+  Zenith Carburetor, Action of                             137
+  Zenith Duplex Carburetor, Troubles in                    356
+  Zenith Carburetor Installation                           139
+
+
+
+
+LIST OF ILLUSTRATIONS
+
+
+Frontispiece. Part Sectional View of Hall-Scott Airplane Motor, Showing
+Principal Parts.
+
+Fig. 1. Diagrams Illustrating Computations for Horse-Power Required for
+Airplane Flight.
+
+Fig. 2. Plate Showing Heavy, Slow Speed Internal Combustion Engines Used
+Only for Stationary Power in Large Installations Giving Weight to
+Horse-Power Ratio.
+
+Fig. 3. Various Forms of Internal Combustion Engines Showing Decrease in
+Weight to Horse-Power Ratio with Augmenting Speed of Rotation.
+
+Fig. 4. Internal Combustion Engine Types of Extremely Fine Construction
+and Refined Design, Showing Great Power Outputs for Very Small Weight, a
+Feature Very Much Desired in Airplane Power Plants.
+
+Fig. 5. Outlining First Two Strokes of Piston in Four-Cycle Engine.
+
+Fig. 6. Outlining Second Two Strokes of Piston in Four-Cycle Engine.
+
+Fig. 7. Sectional View of L Head Gasoline Engine Cylinder Showing Piston
+Movements During Four-Stroke Cycle.
+
+Fig. 8. Showing Two-port, Two-cycle Engine Operation.
+
+Fig. 9. Defining Three-port, Two-cycle Engine Action.
+
+Fig. 10. Diagrams Contrasting Action of Two- and Four-Cycle Cylinders on
+Exhaust and Intake Stroke.
+
+Fig. 11. Diagram Isothermal and Adiabatic Lines.
+
+Fig. 12. Graphic Diagram Showing Approximate Utilization of Fuel Burned
+in Internal-Combustion Engine.
+
+Fig. 13. Otto Four-Cycle Card.
+
+Fig. 14. Diesel Motor Card.
+
+Fig. 15. Diagram of Heat in the Gas Engine Cylinder.
+
+Fig. 16. Chart Showing Relation Between Compression Volume and Pressure.
+
+Fig. 17. The Thompson Indicator, an Instrument for Determining
+Compressions and Explosion Pressure Values and Recording Them on Chart.
+
+Fig. 18. Spherical Combustion Chamber.
+
+Fig. 19. Enlarged Combustion Chamber.
+
+Fig. 20. Mercedes Aviation Engine Cylinder Section Showing Approximately
+Spherical Combustion Chamber and Concave Piston Top.
+
+Fig. 21. Side Sectional View of Typical Airplane Engine, Showing Parts
+and Their Relation to Each Other. This Engine is an Aeromarine Design
+and Utilizes a Distinctive Concentric Valve Construction.
+
+Fig. 22. Diagrams Illustrating Sequence of Cycles in One- and
+Two-Cylinder Engines Showing More Uniform Turning Effort on Crank-Shaft
+with Two-Cylinder Motors.
+
+Fig. 23. Diagrams Demonstrating Clearly Advantages which Obtain when
+Multiple-Cylinder Motors are Used as Power Plants.
+
+Fig. 24. Showing Three Possible Though Unconventional Arrangements of
+Four-Cylinder Engines.
+
+Fig. 25. Diagrams Outlining Advantages of Multiple Cylinder Motors, and
+Why They Deliver Power More Evenly Than Single Cylinder Types.
+
+Fig. 26. Diagrams Showing Duration of Events for a Four-Stroke Cycle,
+Six-Cylinder Engine.
+
+Fig. 27. Diagram Showing Actual Duration of Different Strokes in
+Degrees.
+
+Fig. 28. Another Diagram to Facilitate Understanding Sequence of
+Functions in Six-Cylinder Engine.
+
+Fig. 29. Types of Eight-Cylinder Engines Showing the Advantage of the V
+Method of Cylinder Placing.
+
+Fig. 30. Curves Showing Torque of Various Engine Types Demonstrate
+Graphically Marked Advantage of the Eight-Cylinder Type.
+
+Fig. 31. Diagrams Showing How Increasing Number of Cylinders Makes for
+More Uniform Power Application.
+
+Fig. 32. How the Angle Between the Cylinders of an Eight- and
+Twelve-Cylinder V Motor Varies.
+
+Fig. 33. The Hall-Scott Four-Cylinder 100 Horse-Power Aviation Motor.
+
+Fig. 34. Two Views of the Duesenberg Sixteen Valve Four-Cylinder
+Aviation Motor.
+
+Fig. 35. The Hall-Scott Six-Cylinder Aviation Engine.
+
+Fig. 36. The Curtiss Eight-Cylinder, 200 Horse-Power Aviation Engine.
+
+Fig. 37. The Sturtevant Eight-Cylinder, High Speed Aviation Motor.
+
+Fig. 38. Anzani 40-50 Horse-Power Five-Cylinder Air Cooled Engine.
+
+Fig. 39. Unconventional Six-Cylinder Aircraft Motor of Masson Design.
+
+Fig. 40. The Gnome Fourteen-Cylinder Revolving Motor.
+
+Fig. 41. How Gravity Feed Fuel Tank May Be Mounted Back of Engine and
+Secure Short Fuel Line.
+
+Fig. 42. The Stewart Vacuum Fuel Feed Tank.
+
+Fig. 43. Marine-Type Mixing Valve, by which Gasoline is Sprayed into Air
+Stream Through Small Opening in Air-Valve Seat.
+
+Fig. 44. Tracing Evolution of Modern Spray Carburetor. A--Early Form
+Evolved by Maybach. B.--Phoenix-Daimler Modification of Maybach's
+Principle. C--Modern Concentric Float Automatic Compensating Carburetor.
+
+Fig. 45. New Model of Schebler Carburetor With Metering Valve and
+Extended Venturi. Note Mechanical Connection Between Air Valve and Fuel
+Regulating Needle.
+
+Fig. 46. The Claudel Carburetor.
+
+Fig. 47. The Stewart Metering Pin Carburetor.
+
+Fig. 48. The Ball and Ball Two-Stage Carburetor.
+
+Fig. 49. The Master Carburetor.
+
+Fig. 50. Sectional View of Master Carburetor Showing Parts.
+
+Fig. 51. Sectional View of Zenith Compound Nozzle Compensating
+Carburetor.
+
+Fig. 52. Diagrams Explaining Action of Baverey Compound Nozzle Used in
+Zenith Carburetor.
+
+Fig. 53. The Zenith Duplex Carburetor for Airplane Motors of the V Type.
+
+Fig. 54. Rear View of Curtiss OX-2 90 Horse-Power Airplane Motor Showing
+Carburetor Location and Hot Air Leads.
+
+Fig. 55. Types of Strainers Interposed Between Vaporizer and Gasoline
+Tank to Prevent Water or Dirt Passing Into Carbureting Device.
+
+Fig. 56. Chart Showing Diminution of Air Pressure as Altitude Increases.
+
+Fig. 57. Some Simple Experiments to Demonstrate Various Magnetic
+Phenomena and Clearly Outline Effects of Magnetism and Various Forms of
+Magnets.
+
+Fig. 58. Elementary Form of Magneto Showing Principal Parts Simplified
+to Make Method of Current Generation Clear.
+
+Fig. 59. Showing How Strength of Magnetic Influence and of the Currents
+Induced in the Windings of Armature Vary with the Rapidity of Changes of
+Flow.
+
+Fig. 60. Diagrams Explaining Action of Low Tension Transformer Coil and
+True High Tension Magneto Ignition Systems.
+
+Fig. 60A. Side Sectional View of Bosch High-Tension Magneto Shows
+Disposition of Parts. End Elevation Depicts Arrangement of Interruptor
+and Distributor Mechanism.
+
+Fig. 61. Berling Two-Spark Dual Ignition System.
+
+Fig. 62. Berling Double-Spark Independent System.
+
+Fig. 63. Type DD Berling High Tension Magneto.
+
+Fig. 64. Wiring Diagrams of Berling Magneto Ignition Systems.
+
+Fig. 65. The Berling Magneto Breaker Box Showing Contact Points
+Separated and Interruptor Lever on Cam.
+
+Fig. 66. The Dixie Model 60 for Six-Cylinder Airplane Engine Ignition.
+
+Fig. 67. Installation Dimensions of Dixie Model 60 Magneto.
+
+Fig. 68. The Rotating Elements of the Dixie Magneto.
+
+Fig. 69. Suggestions for Adjusting and Dismantling Dixie Magneto.
+A--Screw Driver Adjusts Contact Points. B--Distributor Block Removed.
+C--Taking off Magnets. D--Showing How Easily Condenser and High Tension
+Windings are Removed.
+
+Fig. 69A. Sectional Views Outlining Construction of Dixie Magneto with
+Compound Distributor for Eight-Cylinder Engine Ignition.
+
+Fig. 70. Wiring Diagram of Dixie Magneto Installation on Hall-Scott
+Six-Cylinder 125 Horse-Power Aeronautic Motor.
+
+Fig. 71. How Magneto Ignition is Installed on Thomas-Morse 135
+Horse-Power Motor.
+
+Fig. 72. Spark-Plug Types Showing Construction and Arrangement of Parts.
+
+Fig. 73. Standard Airplane Engine Plug Suggested by S. A. E. Standards
+Committee.
+
+Fig. 74. Special Mica Plug for Aviation Engines.
+
+Fig. 75. Showing Use of Magnifying Glass to Demonstrate that Apparently
+Smooth Metal Surfaces May Have Minute Irregularities which Produce
+Friction.
+
+Fig. 76. Pressure Feed Oiling System of Thomas Aviation Engine Includes
+Oil Cooling Means.
+
+Fig. 77. Diagram of Oiling System, Hall-Scott Type A 125 Horse-Power
+Engine.
+
+Fig. 78. Sectional View of Typical Motor Showing Parts Needing
+Lubrication and Method of Applying Oil by Constant Level Splash System.
+Note also Water Jacket and Spaces for Water Circulation.
+
+Fig. 79. Pressure Feed Oil-Supply System of Airplane Power Plants has
+Many Good Features.
+
+Fig. 80. Why Pressure Feed System is Best for Eight-Cylinder Vee
+Airplane Engines.
+
+Fig. 81. Operating Temperatures of Automobile Engine Parts Useful as a
+Guide to Understand Airplane Power Plant Heat.
+
+Fig. 82. Water Cooling of Salmson Seven-Cylinder Radial Airplane Engine.
+
+Fig. 83. How Water Cooling System of Thomas Airplane Engine is Installed
+in Fuselage.
+
+Fig. 84. Finned Tube Radiators at the Side of Hall-Scott Airplane Power
+Plant Installed in Standard Fuselage.
+
+Fig. 85. Anzani Testing His Five-Cylinder Air Cooled Aviation Motor
+Installed in Bleriot Monoplane. Note Exposure of Flanged Cylinders to
+Propeller Slip Stream.
+
+Fig. 86. Views of Four-Cylinder Duesenberg Airplane Engine Cylinder
+Block.
+
+Fig. 87. Twin-Cylinder Block of Sturtevant Airplane Engine is Cast of
+Aluminum, and Has Removable Cylinder Head.
+
+Fig. 88. Aluminum Cylinder Pair Casting of Thomas 150 Horse-Power
+Airplane Engine is of the L Head Type.
+
+Fig. 90. Cross Section of Austro-Daimler Engine, Showing Offset Cylinder
+Construction. Note Applied Water Jacket and Peculiar Valve Action.
+
+Fig. 91. Diagrams Demonstrating Advantages of Offset Crank-Shaft
+Construction.
+
+Fig. 92. Diagram Showing Forms of Cylinder Demanded by Different Valve
+Placings. A--T Head Type, Valves on Opposite Sides. B--L Head Cylinder,
+Valves Side by Side. C--L Head Cylinder, One Valve in Head, Other in
+Pocket. D--Inlet Valve Over Exhaust Member, Both in Side Pocket.
+E--Valve-in-the-Head Type with Vertical Valves. F--Inclined Valves
+Placed to Open Directly into Combustion Chamber.
+
+Fig. 93. Sectional View of Engine Cylinder Showing Valve and Cage
+Installation.
+
+Fig. 94. Diagrams Showing How Gas Enters Cylinder Through Overhead
+Valves and Other Types. A--Tee Head Cylinder. B--L Head Cylinder.
+C--Overhead Valve.
+
+Fig. 95. Conventional Methods of Operating Internal Combustion Motor
+Valves.
+
+Fig. 96. Examples of Direct Valve Actuation by Overhead Cam-Shaft.
+A--Mercedes. B--Hall-Scott. C--Wisconsin.
+
+Fig. 97. CENSORED
+
+Fig. 98. CENSORED
+
+Fig. 99. Sectional Views Showing Arrangement of Novel Concentric Valve
+Arrangement Devised by Panhard for Aerial Engines.
+
+Fig. 100. Showing Clearance Allowed Between Valve Stem and Valve Stem
+Guide to Secure Free Action.
+
+Fig. 101. Forms of Valve-Lifting Cams Generally Employed. A--Cam Profile
+for Long Dwell and Quick Lift. B--Typical Inlet Cam Used with Mushroom
+Type Follower. C--Average Form of Cam. D--Designed to Give Quick Lift
+and Gradual Closing.
+
+Fig. 102. Showing Principal Types of Cam Followers which Have Received
+General Application.
+
+Fig. 103. Diagram Showing Proper Clearance to Allow Between Adjusting
+Screw and Valve Stems in Hall-Scott Aviation Engines.
+
+Fig. 104. Cam-Shaft of Thomas Airplane Motor Has Cams Forged Integral.
+Note Split Cam-Shaft Bearings and Method of Gear Retention.
+
+Fig. 105. Section Through Cylinder of Knight Motor, Showing Important
+Parts of Valve Motion.
+
+Fig. 106. Diagrams Showing Knight Sleeve Valve Action.
+
+Fig. 107. Cross Sectional View of Knight Type Eight Cylinder V Engine.
+
+Fig. 108. Diagrams Explaining Valve and Ignition Timing of Hall-Scott
+Aviation Engine.
+
+Fig. 109. Timing Diagram of Typical Six-Cylinder Engine.
+
+Fig. 110. Timing Diagram of Typical Eight-Cylinder V Engine.
+
+Fig. 111. Timing Diagram Showing Peculiar Valve Timing of Gnome
+"Monosoupape" Rotary Motor.
+
+Fig. 112. Two Methods of Operating Valves by Positive Cam Mechanism
+Which Closes as Well as Opens Them.
+
+Fig. 113. Diagram Comparing Two Large Valves and Four Small Ones of
+Practically the Same Area. Note How Easily Small Valves are Installed to
+Open Directly Into the Cylinder.
+
+Fig. 114. Sectional Views of Sixteen-Valve Four-Cylinder Automobile
+Racing Engine That May Have Possibilities for Aviation Service.
+
+Fig. 115. Front View of Curtiss OX-3 Aviation Motor, Showing
+Unconventional Valve Action by Concentric Push Rod and Pull Tube.
+
+Fig. 116. Forms of Pistons Commonly Employed in Gasoline Engines.
+A--Dome Head Piston and Three Packing Rings. B--Flat Top Form Almost
+Universally Used. C--Concave Piston Utilized in Knight Motors and Some
+Having Overhead Valves. D--Two-Cycle Engine Member with Deflector Plate
+Cast Integrally. E--Differential of Two-Diameter Piston Used in Some
+Engines Operating on Two-Cycle Principle.
+
+Fig. 117. Typical Methods of Piston Pin Retention Generally Used in
+Engines of American Design. A--Single Set Screw and Lock Nut. B--Set
+Screw and Check Nut Fitting Groove in Wrist Pin. C, D--Two Locking
+Screws Passing Into Interior of Hollow Wrist Pin. E--Split Ring Holds
+Pin in Place. F--Use of Taper Expanding Plugs Outlined. G--Spring
+Pressed Plunger Type. H--Piston Pin Pinned to Connecting Rod. I--Wrist
+Pin Clamped in Connecting Rod Small End by Bolt.
+
+Fig. 118. Typical Piston and Connecting Rod Assembly.
+
+Fig. 119. Parts of Sturtevant Aviation Engine. A--Cylinder Head Showing
+Valves. B--Connecting Rod. C--Piston and Rings.
+
+Fig. 120. Aluminum Piston and Light But Strong Steel Connecting Rod and
+Wrist Pin of Thomas Aviation Engine.
+
+Fig. 121. Cast Iron Piston of "Monosoupape" Gnome Engine Installed On
+One of the Short Connecting Rods.
+
+Fig. 122. Types of Aluminum Pistons Used In Aviation Engines.
+
+Fig. 123. Types of Piston Rings and Ring Joints. A--Concentric Ring.
+B--Eccentrically Machined Form. C--Lap Joint Ring. D--Butt Joint, Seldom
+Used. E--Diagonal Cut Member, a Popular Form.
+
+Fig. 124. Diagrams Showing Advantages of Concentric Piston Rings.
+
+Fig. 125. Leak-Proof and Other Compound Piston Rings.
+
+Fig. 126. Sectional View of Engine Showing Means of Preventing Oil
+Leakage By Piston Rings.
+
+Fig. 127. Connecting Rod and Crank-Shaft Construction of Gnome
+"Monosoupape" Engine.
+
+Fig. 128. Connecting Rod Types Summarized. A--Single Connecting Rod Made
+in One Piece, Usually Fitted in Small Single-Cylinder Engines Having
+Built-Up Crank-Shafts. B--Marine Type, a Popular Form on Heavy Engines.
+C--Conventional Automobile Type, a Modified Marine Form. D--Type Having
+Hinged Lower Cap and Split Wrist Pin Bushing. E--Connecting Rod Having
+Diagonally Divided Big End. F--Ball-Bearing Rod. G--Sections Showing
+Structural Shapes Commonly Employed in Connecting Rod Construction.
+
+Fig. 129. Double Connecting Rod Assembly For Use On Single Crank-Pin of
+Vee Engine.
+
+Fig. 130. Another Type of Double Connecting Rod for Vee Engines.
+
+Fig. 131. Part Sectional View of Wisconsin Aviation Engine, Showing
+Four-Bearing Crank-Shaft, Overhead Cam-Shaft, and Method of Combining
+Cylinders in Pairs.
+
+Fig. 132. Part Sectional View of Renault Twelve-Cylinder Water-Cooled
+Engine, Showing Connecting Rod Construction and Other Important Internal
+Parts.
+
+Fig. 133. Typical Cam-Shaft, with Valve Lifting Cams and Gears to
+Operate Auxiliary Devices Forged Integrally.
+
+Fig. 134. Important Parts of Duesenberg Aviation Engine. A--Three Main
+Bearing Crank-Shaft. B--Cam-Shaft with Integral Cams. C--Piston and
+Connecting Rod Assembly. D--Valve Rocker Group. E--Piston. F--Main
+Bearing Brasses.
+
+Fig. 135. Showing Method of Making Crank-Shaft. A--The Rough Steel
+Forging Before Machining. B--The Finished Six-Throw, Seven-Bearing
+Crank-Shaft.
+
+Fig. 136. Showing Form of Crank-Shaft for Twin-Cylinder Opposed Power
+Plant.
+
+Fig. 137. Crank-Shaft of Thomas-Morse Eight-Cylinder Vee Engine.
+
+Fig. 138. Crank-Case and Crank-Shaft Construction for Twelve-Cylinder
+Motors. A--Duesenberg. B--Curtiss.
+
+Fig. 139. Counterbalanced Crank-Shafts Reduce Engine Vibration and
+Permit of Higher Rotative Speeds.
+
+Fig. 140. View of Thomas 135 Horse-Power Aeromotor, Model 8, Showing
+Conventional Method of Crank-Case Construction.
+
+Fig. 141. Views of Upper Half of Thomas Aeromotor Crank-Case.
+
+Fig. 142. Method of Constructing Eight-Cylinder Vee Engine, Possible if
+Aluminum Cylinder and Crank-Case Castings are Used.
+
+Fig. 143. Simple and Compact Crank-Case, Possible When Radial Cylinder
+Engine Design is Followed.
+
+Fig. 144. Unconventional Mounting of German Inverted Cylinder Motor.
+
+Fig. 145. How Curtiss Model OX-2 Motor is Installed in Fuselage of
+Curtiss Tractor Biplane. Note Similarity of Mounting to Automobile Power
+Plant.
+
+Fig. 146. Latest Model of Curtiss JN-4 Training Machine, Showing
+Thorough Enclosure of Power Plant and Method of Disposing of the Exhaust
+Gases.
+
+Fig. 147. Front View of L. W. F. Tractor Biplane Fuselage, Showing
+Method of Installing Thomas Aeromotor and Method of Disposing of Exhaust
+Gases.
+
+Fig. 148. End Elevation of Hall-Scott A-7 Four-Cylinder Motor, with
+Installation Dimensions.
+
+Fig. 149. Plan and Side Elevation of Hall-Scott A-7 Four-Cylinder
+Airplane Engine, with Installation Dimensions.
+
+Fig. 150. CENSORED
+
+Fig. 151. CENSORED
+
+Fig. 152. CENSORED
+
+Fig. 153. Plan View of Hall-Scott Type A-5 125 Horse-Power Airplane
+Engine, Showing Installation Dimensions.
+
+Fig. 154. Three-Quarter View of Hall-Scott Type A-5 125 Horse-Power
+Six-Cylinder Engine, with One of the Side Radiators Removed to Show
+Installation in Standard Fuselage.
+
+Fig. 155. Diagram Showing Proper Installation of Hall-Scott Type A-5 125
+Horse-Power Engine with Pressure Feed Fuel Supply System.
+
+Fig. 156. Diagram Defining Installation of Gnome "Monosoupape" Motor in
+Tractor Biplane. Note Necessary Piping for Fuel, Oil, and Air Lines.
+
+Fig. 157. Showing Two Methods of Placing Propeller on Gnome Rotary
+Motor.
+
+Fig. 158. How Gnome Rotary Motor May Be Attached to Airplane Fuselage
+Members.
+
+Fig. 159. How Anzani Ten-Cylinder Radial Engine is Installed to Plate
+Securely Attached to Front End of Tractor Airplane Fuselage.
+
+Fig. 160. Side Elevation of Thomas 135 Horse-Power Airplane Engine,
+Giving Important Dimensions.
+
+Fig. 161. Front Elevation of Thomas-Morse 135 Horse-Power Aeromotor,
+Showing Main Dimensions.
+
+Fig. 162. Front and Side Elevations of Sturtevant Airplane Engine,
+Giving Principal Dimensions to Facilitate Installation.
+
+Fig. 163. Practical Hand Tools Useful in Dismantling and Repairing
+Airplane Engines.
+
+Fig. 164. Wrenches are Offered in Many Forms.
+
+Fig. 165. Illustrating Use and Care of Files.
+
+Fig. 166. Outlining Use of Cotter Pin Pliers, Spring Winder, and Showing
+Practical Outfit of Chisels.
+
+Fig. 167. Forms of Hand Operated Drilling Machines.
+
+Fig. 168. Forms of Drills Used in Hand and Power Drilling Machines.
+
+Fig. 169. Useful Set of Number Drills, Showing Stand for Keeping These
+in an Orderly Manner.
+
+Fig. 170. Illustrating Standard Forms of Hand and Machine Reamers.
+
+Fig. 171. Tools for Thread Cutting.
+
+Fig. 172. Showing Holder Designs for One- and Two-Piece Thread Cutting
+Dies.
+
+Fig. 173. Useful Outfit of Taps and Dies for the Engine Repair Shop.
+
+Fig. 174. Common Forms of Inside and Outside Calipers.
+
+Fig. 175. Measuring Appliances for the Machinist and Floor Man.
+
+Fig. 176. At Left, Special Form of Vernier Caliper for Measuring Gear
+Teeth; at Right, Micrometer for Accurate Internal Measurements.
+
+Fig. 177. Measuring Appliances of Value in Airplane Repair Work.
+
+Fig. 178. Standard Forms of Micrometer Caliper for External
+Measurements.
+
+Fig. 179. Special Tools for Maintaining Curtiss OX-2 Motor Used in
+Curtiss JN-4 Training Biplane.
+
+Fig. 180. Special Tools and Appliances to Facilitate Overhauling Work on
+Hall-Scott Airplane Engines.
+
+Fig. 181. Special Stand to Make Motor Overhauling Work Easier.
+
+Fig. 182. Showing Where Carbon Deposits Collect in Engine Combustion
+Chamber, and How to Burn Them Out with the Aid of Oxygen. A--Special
+Torch. B--Torch Coupled to Oxygen Tank. C--Torch in Use.
+
+Fig. 1821/2. Part Sectional View, Showing Valve Arrangement in Cylinder
+of Curtiss OX-2 Aviation Engine.
+
+Fig. 183. Tools for Restoring Valve Head and Seats.
+
+Fig. 184. Tools and Processes Utilized in Valve Grinding.
+
+Fig. 185. Outlining Points in Valve Operating Mechanism Where
+Depreciation is Apt to Exist.
+
+Fig. 186. Method of Removing Piston Rings, and Simple Clamp to
+Facilitate Insertion of Rings in Cylinder.
+
+Fig. 187. Tools and Processes Used in Refitting Engine Bearings.
+
+Fig. 188. Showing Points to Observe When Fitting Connecting Rod Brasses.
+
+Fig. 189. Methods of Testing to Insure Parallelism of Bearings After
+Fitting.
+
+Fig. 190. Views Outlining Construction of Three-Cylinder Anzani Aviation
+Motor.
+
+Fig. 190a. Illustrations Depicting Wrong and Right Methods of "Swinging
+the Stick" to Start Airplane Engine. At Top, Poor Position to Get Full
+Throw and Get Out of the Way. Below, Correct Position to Get Quick Turn
+Over of Crank-Shaft and Spring Away from Propeller.
+
+Fig. 191. The Anzani Six-Cylinder Water-Cooled Aviation Engine.
+
+Fig. 192. Sectional View of Anzani Six-Cylinder Water-Cooled Aviation
+Engine.
+
+Fig. 193. Three-Cylinder Anzani Air-Cooled Y-Form Engine.
+
+Fig. 194. Anzani Fixed Crank-Case Engine of the Six-Cylinder Form
+Utilizes Air Cooling Successfully.
+
+Fig. 195. Sectional View Showing Internal Parts of Six-Cylinder Anzani
+Engine, with Starwise Disposition of Cylinders.
+
+Fig. 196. The Anzani Ten-Cylinder Aviation Engine at the Left, and the
+Twenty-Cylinder Fixed Type at the Right.
+
+Fig. 197. Application of R. E. P. Five-Cylinder Fan-Shape Air-Cooled
+Motor to Early Monoplane.
+
+Fig. 198. The Canton and Unne Nine-Cylinder Water-Cooled Radial Engine.
+
+Fig. 199. Sectional View Showing Construction of Canton and Unne
+Water-Cooled Radial Cylinder Engine.
+
+Fig. 200. Sectional View Outlining Construction of Early Type Gnome
+Valve-in-Piston Type Motor.
+
+Fig. 201. Sectional View of Early Type Gnome Cylinder and Piston Showing
+Construction and Application of Inlet and Exhaust Valves.
+
+Fig. 202. Details of Old Style Gnome Motor Inlet and Exhaust Valve
+Construction and Operation.
+
+Fig. 203. The Gnome Fourteen-Cylinder 100 Horse-Power Aviation Engine.
+
+Fig. 204. Cam and Cam-Gear Case of the Gnome Seven-Cylinder Revolving
+Engine.
+
+Fig. 205. Diagrams Showing Why An Odd Number of Cylinders is Best for
+Rotary Cylinder Motors.
+
+Fig. 206. Simple Carburetor Used On Early Gnome Engines Attached to
+Fixed Crank-Shaft End.
+
+Fig. 207. Sectional Views of the Gnome Oil Pump.
+
+Fig. 208. Simplified Diagram Showing Gnome Motor Magneto Ignition
+System.
+
+Fig. 209. The G. V. Gnome "Monosoupape" Nine-Cylinder Rotary Engine
+Mounted on Testing Stand.
+
+Fig. 210. Sectional View Showing Construction of General Vehicle Co.
+"Monosoupape" Gnome Engine.
+
+Fig. 211. How a Gnome Cylinder is Reduced from Solid Chunk of Steel
+Weighing 97 Pounds to Finished Cylinder Weighing 51/2 Pounds.
+
+Fig. 212. The Gnome Engine Cam-Gear Case, a Fine Example of Accurate
+Machine Work.
+
+Fig. 213. G. V. Gnome "Monosoupape," with Cam-Case Cover Removed to Show
+Cams and Valve-Operating Plungers with Roller Cam Followers.
+
+Fig. 214. The 50 Horse-Power Rotary Bayerischen Motoren Gesellschaft
+Engine, a German Adaptation of the Early Gnome Design.
+
+Fig. 215. Nine-Cylinder Revolving Le Rhone Type Aviation Engine.
+
+Fig. 216. Part Sectional Views of Le Rhone Rotary Cylinder Engine,
+Showing Method of Cylinder Retention, Valve Operation and Novel Crank
+Disc Assembly.
+
+Fig. 217. Side Sectional View of Le Rhone Aviation Engine.
+
+Fig. 218. View Showing Le Rhone Valve Action and Connecting Rod Big End
+Arrangement.
+
+Fig. 219. Diagrams Showing Important Components of Le Rhone Motor.
+
+Fig. 220. How the Cams of the Le Rhone Motor Can Operate Two Valves with
+a Single Push Rod.
+
+Fig. 221. The Le Rhone Carburetor at A and Fuel Supply Regulating Device
+at B.
+
+Fig. 222. Diagrams Showing Le Rhone Motor Action and Firing Order.
+
+Fig. 223. Diagram Showing Positions of Piston in Le Rhone Rotary
+Cylinder Motor.
+
+Fig. 224. Diagrams Showing Valve Timing of Le Rhone Aviation Engine.
+
+Fig. 225. Diagrams Showing How Cylinder Cooling is Effected in Renault
+Vee Engines.
+
+Fig. 226. End Sectional View of Renault Air-Cooled Aviation Engine.
+
+Fig. 227. Side Sectional View of Renault Twelve-Cylinder Air-Cooled
+Aviation Engine Crank-Case, Showing Use of Plain and Ball Bearings for
+Crank-Shaft Support.
+
+Fig. 228. End View of Renault Twelve-Cylinder Engine Crank-Case, Showing
+Magneto Mounting.
+
+Fig. 229. Diagram Outlining Renault Twelve-Cylinder Engine Ignition
+System.
+
+Fig. 230. The Simplex Model A Hispano-Suiza Aviation Engine, a Very
+Successful Form.
+
+Fig. 231. The Curtiss OXX-5 Aviation Engine is an Eight-Cylinder Type
+Largely Used on Training Machines.
+
+Fig. 232. Top and Bottom Views of the Curtiss OXX-5 100 Horse-Power
+Aviation Engine.
+
+Fig. 233. End View of Thomas-Morse 150 Horse-Power Aluminum Cylinder
+Aviation Motor Having Detachable Cylinder Heads.
+
+Fig. 234. Side View of Thomas-Morse High Speed 150 Horse-Power Aviation
+Motor with Geared Down Propeller Drive.
+
+Fig. 235. The Reduction Gear-Case of Thomas-Morse 150 Horse-Power
+Aviation Motor, Showing Ball Bearing and Propeller Drive Shaft Gear.
+
+Fig. 236. The Six-Cylinder Aeromarine Engine.
+
+Fig. 237. The Wisconsin Aviation Engine, at Top, as Viewed from
+Carburetor Side. Below, the Exhaust Side.
+
+Fig. 238. Dimensioned End Elevation of Wisconsin Six Motor.
+
+Fig. 239. Dimensioned Side Elevation of Wisconsin Six Motor.
+
+Fig. 240. Power, Torque and Efficiency Curves of Wisconsin Aviation
+Motor.
+
+Fig. 241. Timing Diagram, Wisconsin Aviation Engine.
+
+Fig. 242. Dimensioned End View of Wisconsin Twelve-Cylinder Airplane
+Motor.
+
+Fig. 243. Dimensioned Side Elevation of Wisconsin Twelve-Cylinder
+Airplane Motor.
+
+Fig. 244. Side and End Sectional Views of Four-Cylinder Argus Engine, a
+German 100 Horse-Power Design Having Bore and Stroke of 140 mm., or 5.60
+inches, and Developing Its Power at 1,368 R.P.M. Weight, 350 Pounds.
+
+Fig. 245. Part Sectional View of 90 Horse-Power Mercedes Engine, Which
+is Typical of the Design of Larger Sizes.
+
+Fig. 246. Part Sectional Side View and Sectional End View of Benz 160
+Horse-Power Aviation Engine.
+
+Fig. 247. At Top, the Sunbeam Overhead Valve 170 Horse-Power
+Six-Cylinder Engine. Below, Side View of Sunbeam 350 Horse-Power
+Twelve-Cylinder Vee Engine.
+
+Fig. 248. Side View of Eighteen-Cylinder Sunbeam Coatalen Aircraft
+Engine Rated at 475 B.H.P.
+
+Fig. 249. Sunbeam Eighteen-Cylinder Motor, Viewed from Pump and Magneto
+End.
+
+Fig. 250. Propeller End of Sunbeam Eighteen-Cylinder 475 B.H.P. Aviation
+Engine.
+
+Fig. 251. View of Airplane Cowl Board, Showing the Various Navigating
+and Indicating Instruments to Aid the Aviator in Flight.
+
+Fig. 252. Parts of Christensen Air Starting System Shown at A, and
+Application of Piping and Check Valves to Cylinders of Thomas-Morse
+Aeromotor Outlined at B.
+
+Fig. 253. Diagrams Showing Installation of Air Starting System on
+Thomas-Morse Aviation Motor.
+
+
+
+
+  CATALOGUE
+  _Of the_ LATEST _and_ BEST
+  PRACTICAL _and_ MECHANICAL
+  BOOKS
+
+  _Including Automobile and Aviation Books_
+
+  [Illustration]
+
+
+  _Any of these books will be sent prepaid to any part of the world, on
+  receipt of price. Remit by Draft, Postal Order, Express Order or
+  Registered Letter_
+
+
+  Published and For Sale By
+  The Norman W. Henley Publishing Co.,
+  2 West 45th Street, New York, U.S.A.
+
+
+
+
+  INDEX
+
+                                             PAGES
+  Air Brakes                                21, 24
+  Arithmetic                            14, 25, 31
+  Automobile Books                      3, 4, 5, 6
+  Automobile Charts                           6, 7
+  Automobile Ignition Systems                    5
+  Automobile Lighting                            5
+  Automobile Questions and Answers               4
+  Automobile Repairing                           4
+  Automobile Starting Systems                    5
+  Automobile Trouble Charts                   5, 6
+  Automobile Welding                             5
+  Aviation                                       7
+  Aviation Chart                                 7
+  Batteries, Storage                             5
+  Bevel Gear                                    19
+  Boiler-Room Chart                              9
+  Brazing                                        7
+  Cams                                          19
+  Carburetion Trouble Chart                      6
+  Change Gear                                   19
+  Charts                                   6, 7, 8
+  Coal                                          22
+  Coke                                           9
+  Combustion                                    22
+  Compressed Air                                10
+  Concrete                              10, 11, 12
+  Concrete for Farm Use                         11
+  Concrete for Shop Use                         11
+  Cosmetics                                     27
+  Cyclecars                                      5
+  Dictionary                                    12
+  Dies                                      12, 13
+  Drawing                                   13, 14
+  Drawing for Plumbers                          28
+  Drop Forging                                  13
+  Dynamo Building                               14
+  Electric Bells                                14
+  Electric Switchboards                     14, 16
+  Electric Toy Making                           15
+  Electric Wiring                       14, 15, 16
+  Electricity                       14, 15, 16, 17
+  Encyclopedia                                  24
+  E-T Air Brake                                 24
+  Every-day Engineering                         34
+  Factory Management                            17
+  Ford Automobile                                3
+  Ford Trouble Chart                             6
+  Formulas and Recipes                          29
+  Fuel                                          17
+  Gas Construction                              18
+  Gas Engines                               18, 19
+  Gas Tractor                                   33
+  Gearing and Cams                              19
+  Glossary of Aviation Terms                 7, 12
+  Heating                                   31, 32
+  Horse-Power Chart                              9
+  Hot-Water Heating                         31, 32
+  House Wiring                              15, 17
+  How to Run an Automobile                       3
+  Hydraulics                                     5
+  Ice and Refrigeration                         20
+  Ignition Systems                               5
+  Ignition-Trouble Chart                         6
+  India Rubber                                  30
+  Interchangeable Manufacturing                 24
+  Inventions                                    20
+  Knots                                         20
+  Lathe Work                                    20
+  Link Motions                                  22
+  Liquid Air                                    21
+  Locomotive Boilers                            22
+  Locomotive Breakdowns                         22
+  Locomotive Engineering            21, 22, 23, 24
+  Machinist Book                        24, 25, 26
+  Magazine, Mechanical                          34
+  Manual Training                               26
+  Marine Engineering                            26
+  Marine Gasoline Engines                       19
+  Mechanical Drawing                        13, 14
+  Mechanical Magazine                           34
+  Mechanical Movements                          25
+  Metal Work                                12, 13
+  Motorcycles                                 5, 6
+  Patents                                       20
+  Pattern Making                                27
+  Perfumery                                     27
+  Perspective                                   13
+  Plumbing                                  28, 29
+  Producer Gas                                  19
+  Punches                                       13
+  Questions and Answers on Automobile            4
+  Questions on Heating                          32
+  Railroad Accidents                            23
+  Railroad Charts                                9
+  Recipe Book                                   29
+  Refrigeration                                 20
+  Repairing Automobiles                          4
+  Rope Work                                     20
+  Rubber                                        30
+  Rubber Stamps                                 30
+  Saw Filing                                    30
+  Saws, Management of                           30
+  Sheet-Metal Works                         12, 13
+  Shop Construction                             25
+  Shop Management                               25
+  Shop Practice                                 25
+  Shop Tools                                    25
+  Sketching Paper                               14
+  Soldering                                      7
+  Splices and Rope Work                         20
+  Steam Engineering                         30, 31
+  Steam Heating                             31, 32
+  Steel                                         32
+  Storage Batteries                              5
+  Submarine Chart                                9
+  Switchboards                              14, 16
+  Tapers                                        21
+  Telegraphy, Wireless                          17
+  Telephone                                     16
+  Thread Cutting                                26
+  Tool Making                                   24
+  Toy Making                                    15
+  Train Rules                                   23
+  Tractive Power Chart                           9
+  Tractor, Gas                                  33
+  Turbines                                      33
+  Vacuum Heating                                32
+  Valve Setting                                 22
+  Ventilation                                   31
+  Watch Making                                  33
+  Waterproofing                                 12
+  Welding with Oxy-acetylene Flame           5, 33
+  Wireless Telegraphy                           17
+  Wiring                                    14, 15
+  Wiring Diagrams                               14
+
+
+Any of these books promptly sent prepaid to any address in the world on
+receipt of price.
+
+=HOW TO REMIT=--By Postal Money Order, Express Money Order, Bank Draft
+or Registered Letter.
+
+
+~AUTOMOBILES AND MOTORCYCLES~
+
+
+=The Modern Gasoline Automobile--Its Design, Construction, and
+Operation, 1918 Edition.= By VICTOR W. PAGE, M.S.A.E.
+
+    This is the most complete, practical and up-to-date treatise on
+    gasoline automobiles and their component parts ever published.
+    In the new _revised_ and _enlarged_ 1918 _edition_, all phases
+    of automobile construction, operation and maintenance are fully
+    and completely described, and in language anyone can understand.
+    Every part of all types of automobiles, from light cycle-cars to
+    heavy motor trucks and tractors, are described in a thorough
+    manner, not only the automobile, but every item of it;
+    equipment, accessories, tools needed, supplies and spare parts
+    necessary for its upkeep, are fully discussed.
+
+    _It is clearly and concisely written by an expert familiar with
+    every branch of the automobile industry and the originator of
+    the practical system of self-education on technical subjects. It
+    is a liberal education in the automobile art, useful to all who
+    motor for either business or pleasure._
+
+    Anyone reading the incomparable treatise is in touch with all
+    improvements that have been made in motor-car construction. All
+    latest developments, such as high speed aluminum motors and
+    multiple valve and sleeve-valve engines, are considered in
+    detail. The latest ignition, carburetor and lubrication practice
+    is outlined. New forms of change speed gears, and final power
+    transmission systems, and all latest chassis improvements are
+    shown and described. This book is used in all leading automobile
+    schools and is conceded to be the STANDARD TREATISE. The chapter
+    on Starting and Lighting Systems has been greatly enlarged, and
+    many automobile engineering features that have long puzzled
+    laymen are explained so clearly that the underlying principles
+    can be understood by anyone. This book was first published six
+    years ago and so much new matter has been added that it is
+    nearly twice, its original size. The only treatise covering
+    various forms of war automobiles and recent developments in
+    motor-truck design as well as pleasure cars. _This book is not
+    too technical for the layman nor too elementary for the more
+    expert. It is an incomparable work of reference, for home or
+    school_. 1,000 6x9 pages, nearly 1,000 illustrations, 12 folding
+    plates. Cloth bound. Price =$3.00=
+
+    WHAT IS SAID OF THIS BOOK:
+
+    "It is the best book on the Automobile seen up to date."--J. H.
+    Pile, Associate Editor _Automobile Trade Journal_.
+
+    "Every Automobile Owner has use for a book of this
+    character."--_The Tradesman_.
+
+    "This book is superior to any treatise heretofore published on
+    the subject."--_The Inventive Age_.
+
+    "We know of no other volume that is so complete in all its
+    departments, and in which the wide field of automobile
+    construction with its mechanical intricacies is so plainly
+    handled, both in the text and in the matter of
+    illustrations."--_The Motorist_.
+
+    "The book is very thorough, a careful examination failing to
+    disclose any point in connection with the automobile, its care
+    and repair, to have been overlooked."--_Iron Age_.
+
+    "Mr. Page has done a great work, and benefit to the Automobile
+    Field."--W. C. Hasford, Mgr. Y. M. C. A. Automobile School,
+    Boston, Mass.
+
+    "It is just the kind of a book a motorist needs if he wants to
+    understand his car."--_American Thresherman_.
+
+
+=The Model T Ford Car, Its Construction, Operation and Repair.= By
+VICTOR W. PAGE, M.S.A.E.
+
+    This is a complete instruction book. All parts of the Ford Model
+    T Car are described and illustrated; the construction is fully
+    described and operating principles made clear to everyone. Every
+    Ford owner needs this practical book. You don't have to guess
+    about the construction or where the trouble is, as it shows how
+    to take all parts apart and how to locate and fix all faults.
+    The writer, Mr. Page, has operated a Ford car for many years and
+    writes from actual knowledge. Among the contents are: 1. The
+    Ford Car: Its Parts and Their Functions. 2. The Engine and
+    Auxiliary Groups. How the Engine Works--The Fuel Supply
+    System--The Carburetor--Making the Ignition Spark--Cooling and
+    Lubrication. 3. Details of Chassis. Change Speed Gear--Power
+    Transmission--Differential Gear Action--Steering Gear--Front
+    Axle--Frame and Springs--Brakes. 4. How to Drive and Care for
+    the Ford. The Control System Explained--Starting the
+    Motor--Driving the Car--Locating Roadside Troubles--Tire
+    Repairs--Oiling the Chassis--Winter Care of Car. 5. Systematic
+    Location of Troubles and Remedies. Faults in Engine--Faults in
+    Carburetor--Ignition Troubles--Cooling and Lubrication System
+    Defects--Adjustment of Transmission Gear--General Chassis
+    Repairs. 95 illustrations, 300 pages, 2 large folding plates.
+    Price =$1.00=
+
+
+=How to Run an Automobile.= By VICTOR W. PAGE, M.S.A.E.
+
+    This treatise gives concise instructions for starting and
+    running all makes of gasoline automobiles, how to care for them,
+    and gives distinctive features of control. Describes every step
+    for shifting gears, controlling engines, etc. Among the chapters
+    contained are: I.--Automobile Parts and Their Functions.
+    II.--General Starting and Driving Instructions. III.--Typical
+    1917 Control Systems. IV.--Care of Automobiles. 178 pages. 72
+    specially made illustrations. Price =$1.00=
+
+
+=Automobile Repairing Made Easy.= By VICTOR W. PAGE, M.S.A.E.
+
+    A comprehensive, practical exposition of every phase of modern
+    automobile repairing practice. Outlines every process incidental
+    to motor car restoration. Gives plans for workshop construction,
+    suggestions for equipment, power needed, machinery and tools
+    necessary to carry on business successfully. Tells how to
+    overhaul and repair all parts of all automobiles. Everything is
+    explained so simply that motorists and students can acquire a
+    full working knowledge of automobile repairing. This work starts
+    with the engine, then considers carburetion, ignition, cooling
+    and lubrication systems. The clutch, change speed gearing and
+    transmission system are considered in detail. Contains
+    instructions for repairing all types of axles, steering gears
+    and other chassis parts. Many tables, short cuts in figuring and
+    rules of practice are given for the mechanic. Explains fully
+    valve and magneto timing, "tuning" engines, systematic location
+    of trouble, repair of ball and roller bearings, shop kinks,
+    first aid to injured and a multitude of subjects of interest to
+    all in the garage and repair business. _This book contains
+    special instructions on electric starting_, _lighting and
+    ignition systems_, tire _repairing and rebuilding_, _autogenous
+    welding_, _brazing and soldering_, _heat treatment of steel_,
+    _latest timing practice_, _eight and twelve-cylinder motors_,
+    _etc._ 5-3/4x8. Cloth. 1,056 pages, 1,000 illustrations, 11
+    folding plates. Price =$3.00=
+
+    WHAT IS SAID OF THIS BOOK:
+
+    "'Automobile Repairing Made Easy' is the best book on the
+    subject I have ever seen and the only book I ever saw that is of
+    any value in a garage."--Fred Jeffrey, Martinsburg, Neb. "I wish
+    to thank you for sending me a copy of 'Automobile Repairing Made
+    Easy.' I do not think it could be excelled."--S. W. Gisriel,
+    Director of Instruction, Y. M. C. A., Philadelphia, Pa.
+
+
+=Questions and Answers Relating to Modern Automobile Construction,
+Driving and Repair.= By VICTOR W. PAGE, M.S.A.E.
+
+    A practical self-instructor for students, mechanics and
+    motorists, consisting of thirty-seven lessons in the form of
+    questions and answers, written with special reference to the
+    requirements of the non-technical reader desiring easily
+    understood, explanatory matter relating to all branches of
+    automobiling. The subject-matter is absolutely correct and
+    explained in simple language. If you can't answer all of the
+    following questions, you need this work. The answers to these
+    and over 2,000 more are to be found in its pages. Give the name
+    of all important parts of an automobile and describe their
+    functions. Describe action of latest types of kerosene
+    carburetors. What is the difference between a "double" ignition
+    system and a "dual" ignition system? Name parts of an induction
+    coil. How are valves timed? What is an electric motor starter
+    and how does it work? What are advantages of worm drive gearing?
+    Name all important types of ball and roller bearings. What is a
+    "three-quarter" floating axle? What is a two-speed axle? What is
+    the Vulcan electric gear shift? Name the causes of lost power in
+    automobiles. Describe all noises due to deranged mechanism and
+    give causes? How can you adjust a carburetor by the color of the
+    exhaust gases? What causes "popping" in the carburetor? What
+    tools and supplies are needed to equip a car? How do you drive
+    various makes of cars? What is a differential lock and where is
+    it used? Name different systems of wire wheel construction,
+    etc., etc. A popular work at a popular price. 5-1/4x7-1/2.
+    Cloth. 650 pages, 350 illustrations, 3 folding plates. Price
+    =$1.50=
+
+    WHAT IS SAID OF THIS BOOK:
+
+    "If you own a car--get this book."--_The Glassworker_.
+
+    "Mr. Page has the faculty of making difficult subjects plain and
+    understandable."--_Bristol Press_.
+
+    "We can name no writer better qualified to prepare a book of
+    instruction on automobiles than Mr. Victor W.
+    Page."--_Scientific American_.
+
+    "The best automobile catechism that has appeared."--_Automobile
+    Topics_.
+
+    "There are few men, even with long experience, who will not find
+    this book useful. Great pains have been taken to make it
+    accurate. Special recommendation must be given to the
+    illustrations, which have been made specially for the work. Such
+    excellent books as this greatly assist in fully understanding
+    your automobile."--_Engineering News_.
+
+
+=The Automobilist's Pocket Companion and Expense Record.= Arranged by
+VICTOR W. PAGE, M.S.A.E.
+
+    This book is not only valuable as a convenient cost record but
+    contains much information of value to motorists. Includes a
+    condensed digest of auto laws of all States, a lubrication
+    schedule, hints for care of storage battery and care of tires,
+    location of road troubles, anti-freezing solutions, horse-power
+    table, driving hints and many useful tables and recipes of
+    interest to all motorists. Not a technical book in any sense of
+    the word, just a collection of practical facts in simple
+    language for the everyday motorist. Price =$1.00=
+
+
+=Modern Starting, Lighting and Ignition Systems.= By VICTOR W. PAGE,
+M.E.
+
+    This practical volume has been written with special reference to
+    the requirements of the non-technical reader desiring easily
+    understood, explanatory matter, relating to all types of
+    automobile ignition, starting and lighting systems. It can be
+    understood by anyone, even without electrical knowledge, because
+    elementary electrical principles are considered before any
+    attempt is made to discuss features of the various systems.
+    These basic principles are clearly stated and illustrated with
+    simple diagrams. _All the leading systems of starting, lighting
+    and ignition have been described and illustrated with the
+    co-operation of the experts employed by the manufacturers._
+    Wiring diagrams are shown in both technical and non-technical
+    forms. All symbols are fully explained. It is a comprehensive
+    review of modern starting and ignition system practice, and
+    includes a complete exposition of storage battery construction,
+    care and repair. All types of starting motors, generators,
+    magnetos, and all ignition or lighting system-units are fully
+    explained. _Every person in the automobile business needs this
+    volume._ Among some of the subjects treated are: I.--Elementary
+    Electricity; Current Production; Flow; Circuits; Measurements;
+    Definitions; Magnetism; Battery Action; Generator Action.
+    II.--Battery Ignition Systems. III.--Magneto Ignition Systems.
+    IV.--Elementary Exposition of Starting System Principles.
+    V.--Typical Starting and Lighting Systems; Practical
+    Application; Wiring Diagrams; Auto-lite, Bijur, Delco,
+    Dyneto-Entz, Gray and Davis, Remy, U. S. L., Westinghouse,
+    Bosch-Rushmore, Genemotor, North-East, etc. VI.--Locating and
+    Repairing Troubles in Starting and Lighting Systems.
+    VII.--Auxiliary. Electric Systems; Gear-shifting by Electricity;
+    Warning Signals; Electric Brake; Entz-Transmission, Wagner-Saxon
+    Circuits, Wagner-Studebaker Circuits. 5-1/4x7-1/2. Cloth. 530
+    pages, 297 illustrations, 3 folding plates. Price =$1.50=
+
+
+=Automobile Welding With the Oxy-Acetylene Flame.= By M. KEITH DUNHAM.
+
+    This is the only complete book on the "why" and "how" of Welding
+    with the Oxy-Acetylene Flame, and from its pages one can gain
+    information so that he can weld anything that comes along.
+
+    No one can afford to be without this concise book, as it first
+    explains the apparatus to be used, and then covers in detail the
+    actual welding of all automobile parts. The welding of aluminum,
+    cast iron, steel, copper, brass and malleable iron is clearly
+    explained, as well as the proper way to burn the carbon out of
+    the combustion head of the motor. Among the contents are:
+    Chapter I.--Apparatus Knowledge. Chapter II.--Shop Equipment and
+    Initial Procedure. Chapter III.--Cast Iron. Chapter
+    IV.--Aluminum. Chapter V.--Steel. Chapter VI.--Malleable Iron,
+    Copper, Brass, Bronze. Chapter VII.--Carbon Burning and other
+    Uses of Oxygen and Acetylene. Chapter VIII.--How to Figure Cost
+    of Welding. 167 pages, fully illustrated. Price =$1.00=
+
+
+=Storage Batteries Simplified.= By VICTOR W. PAGE, M.S.A.E.
+
+    A comprehensive treatise devoted entirely to secondary batteries
+    and their maintenance, repair and use.
+
+    This is the most up-to-date book on this subject. Describes
+    fully the Exide, Edison, Gould, Willard, U. S. L. and other
+    storage battery forms in the types best suited for automobile,
+    stationary and marine work. Nothing of importance has been
+    omitted that the reader should know about the practical
+    operation and care of storage batteries. No details have been
+    slighted. The instructions for charging and care have been made
+    as simple as possible. Brief Synopsis of Chapters: Chapter
+    I.--Storage Battery Development; Types of Storage Batteries;
+    Lead Plate Types; The Edison Cell. Chapter II.--Storage Battery
+    Construction; Plates and Girds; Plante Plates; Faure Plates;
+    Non-Lead Plates; Commercial Battery Designs. Chapter
+    III.--Charging Methods; Rectifiers; Converters; Rheostats; Rules
+    for Charging. Chapter IV.--Battery Repairs and Maintenance.
+    Chapter V.--Industrial Application of Storage Batteries;
+    Glossary of Storage Battery Terms. 208 Pages. Very Fully
+    Illustrated. Price =$1.50 net=.
+
+
+=Motorcycles, Side Cars and Cyclecars; their Construction, Management
+and Repair.= By VICTOR W. PAGE, M.S.A.E.
+
+    The only complete work published for the motorcyclist and
+    cyclecarist. Describes fully all leading types of machines,
+    their design, construction, maintenance, operation and repair.
+    This treatise outlines fully the operation of two- and
+    four-cycle power plants and all ignition, carburetion and
+    lubrication systems in detail. Describes all representative
+    types of free engine clutches, variable speed gears and power
+    transmission systems. Gives complete instructions for operating
+    and repairing all types. Considers fully electric self-starting
+    and lighting systems, all types of spring frames and spring
+    forks and shows leading control methods. For those desiring
+    technical information a complete series of tables and many
+    formulae to assist in designing are included. The work tells how
+    to figure power needed to climb grades, overcome air resistance
+    and attain high speeds. It shows how to select gear ratios for
+    various weights and powers, how to figure braking efficiency
+    required, gives sizes of belts and chains to transmit power
+    safely, and shows how to design sprockets, belt pulleys, etc.
+    This work also includes complete formulae for figuring
+    horse-power, shows how dynamometer tests are made, defines
+    relative efficiency of air and water-cooled engines, plain and
+    anti-friction bearings and many other data of a practical,
+    helpful, engineering nature. Remember that you get this
+    information in addition to the practical description and
+    instructions which alone are worth several times the price of
+    the book. 550 pages. 350 specially made illustrations, 5 folding
+    plates. Cloth. Price =$1.50=
+
+    WHAT IS SAID OF THIS BOOK:
+
+    "Here is a book that should be in the cycle repairer's
+    kit."--_American Blacksmith._
+
+    "The best way for any rider to thoroughly understand his
+    machine, is to get a copy of this book; it is worth many times
+    its price."--_Pacific Motorcyclist._
+
+
+~AUTOMOBILE AND MOTORCYCLE CHARTS~
+
+
+=Chart. Location of Gasoline Engine Troubles Made Easy--A Chart Showing
+Sectional View of Gasoline Engine.= Compiled by VICTOR W. PAGE, M.S.A.E.
+
+    It shows clearly all parts of a typical four-cylinder gasoline
+    engine of the four-cycle type.
+
+    It outlines distinctly all parts liable to give trouble and also
+    details the derangements apt to interfere with smooth engine
+    operation.
+
+    Valuable to students, motorists, mechanics, repairmen,
+    garagemen, automobile salesmen, chauffeurs, motorboat owners,
+    motor-truck and tractor drivers, aviators, motor-cyclists, and
+    all others who have to do with gasoline power plants.
+
+    It simplifies location of all engine troubles, and while it will
+    prove invaluable to the novice, it can be used to advantage by
+    the more expert. It should be on the walls of every public and
+    private garage, automobile repair shop, club house or school. It
+    can be carried in the automobile or pocket with ease, and will
+    insure against loss of time when engine trouble manifests
+    itself.
+
+    This sectional view of engine is a complete review of all motor
+    troubles. It is prepared by a practical motorist for all who
+    motor. More information for the money than ever before offered.
+    No details omitted. Size 25x38 inches. Securely mailed on
+    receipt of =25 Cents=
+
+
+=Chart. Location of Ford Engine Troubles Made Easy.= Compiled by VICTOR
+W. PAGE, M.S.A.E.
+
+    This shows clear sectional views depicting all portions of the
+    Ford power plant and auxiliary groups. It outlines clearly all
+    parts of the engine, fuel supply system, ignition group and
+    cooling system, that are apt to give trouble, detailing all
+    derangements that are liable to make an engine lose power, start
+    hard or work irregularly. This chart is valuable to students,
+    owners, and drivers, as it simplifies location of all engine
+    faults. Of great advantage as an instructor for the novice, it
+    can be used equally well by the more expert as a work of
+    reference and review. It can be carried in the tool-box or
+    pocket with ease and will save its cost in labor eliminated the
+    first time engine trouble manifests itself. Prepared with
+    special reference to the average man's needs and is a practical
+    review of all motor troubles because it is based on the actual
+    experience of an automobile engineer-mechanic with the mechanism
+    the chart describes. It enables the non-technical owner or
+    operator of a Ford car to locate engine derangements by
+    systematic search, guided by easily recognized symptoms instead
+    of by guesswork. It makes the average owner independent of the
+    roadside repair shop when touring. Must be seen to be
+    appreciated. Size 25x38 inches. Printed on heavy bond paper.
+    Price =25 cents=
+
+
+=Chart. Lubrication of the Motor Car Chassis.= Compiled by VICTOR W.
+PAGE, M.S.A.E.
+
+    This chart presents the plan view of a typical six-cylinder
+    chassis of standard design and all parts are clearly indicated
+    that demand oil, also the frequency with which they must be
+    lubricated and the kind of oil to use. A practical chart for all
+    interested in motor-car maintenance. Size 24x38 inches. Price
+    =25 cents=
+
+
+=Chart. Location of Carburetion Troubles Made Easy.= Compiled by VICTOR
+W. PAGE, M.S.A.E.
+
+    This chart shows all parts of a typical pressure feed fuel
+    supply system and gives causes of trouble, how to locate defects
+    and means of remedying them. Size 24x38 inches. Price =25 cents=
+
+
+=Chart. Location of Ignition System Troubles Made Easy.= Compiled by
+VICTOR W. PAGE, M.S.A.E.
+
+    In this diagram all parts of a typical double ignition system
+    using battery and magneto current are shown, and suggestions are
+    given for readily finding ignition troubles and eliminating them
+    when found. Size 24x38 inches. Price =25 cents=
+
+
+=Chart. Location of Cooling and Lubrication System Faults.= Compiled by
+VICTOR W. PAGE, M.S.A.E.
+
+    This composite diagram shows a typical automobile power plant
+    using pump circulated water-cooling system and the most popular
+    lubrication method. Gives suggestions for curing all overheating
+    and loss of power faults due to faulty action of the oiling or
+    cooling group. Size 24x38 inches. Price =25 cents=
+
+
+=Chart. Motorcycle Troubles Made Easy.= Compiled by VICTOR W PAGE,
+M.S.A.E.
+
+    A chart showing sectional view of a single-cylinder gasoline
+    engine. This chart simplifies location of all power-plant
+    troubles. A single-cylinder motor is shown for simplicity. It
+    outlines distinctly all parts liable to give trouble and also
+    details the derangements apt to interfere with smooth engine
+    operation. This chart will prove of value to all who have to do
+    with the operation, repair or sale of motorcycles. No details
+    omitted. Size 30x20 inches Price =25 cents=
+
+
+~AVIATION~
+
+
+=Aviation Engines, their Design, Construction, Operation and Repair.= By
+Lieut. VICTOR W. PAGE, Aviation Section, S.C.U.S.R.
+
+    A practical work containing valuable instructions for aviation
+    students, mechanicians, squadron engineering officers and all
+    interested in the construction and upkeep of airplane power
+    plants.
+
+    The rapidly increasing interest in the study of aviation, and
+    especially of the highly developed internal combustion engines
+    that make mechanical flight possible, has created a demand for a
+    text-book suitable for schools and home study that will clearly
+    and concisely explain the workings of the various aircraft
+    engines of foreign and domestic manufacture.
+
+    This treatise, written by a recognized authority on all of the
+    practical aspects of internal combustion engine construction,
+    maintenance and repair fills the need as no other book does.
+
+    The matter is logically arranged; all descriptive matter is
+    simply expressed and copiously illustrated so that anyone can
+    understand airplane engine operation and repair even if without
+    previous mechanical training. This work is invaluable for anyone
+    desiring to become an aviator or aviation mechanician.
+
+    The latest rotary types, such as the Gnome, Monosoupape, and Le
+    Rhone, are fully explained, as well as the recently developed
+    Vee and radial types. The subjects of carburetion, ignition,
+    cooling and lubrication also are covered in a thorough manner.
+    The chapters on repair and maintenance are distinctive and found
+    in no other book on this subject.
+
+    Invaluable to the student, mechanic and soldier wishing to enter
+    the aviation service.
+
+    Not a technical book, but a practical, easily understood work of
+    reference for all interested in aeronautical science. 576 octavo
+    pages. 253 specially made engravings. Price =$3.00 net=
+
+
+~GLOSSARY OF AVIATION TERMS~
+
+
+=Termes D'Aviation, English-French, French-English.= Compiled by Lieuts.
+VICTOR W. PAGE, A.S., S.C.U.S.R., and PAUL MONTARIOL of the French
+Flying Corps, on duty on Signal Corps Aviation School, Mineola, L. I.
+
+    A complete, well illustrated volume intended to facilitate
+    conversation between English-speaking and French aviators. A
+    very valuable book for all who are about to leave for duty
+    overseas.
+
+    Approved for publication by Major W. G. Kilner, S.C., U.S.C.O.
+    Signal Corps Aviation School. Hazelhurst Field, Mineola, L. I.
+
+    This book should be in every Aviator's and Mechanic's Kit for
+    ready reference. 128 pages. Fully illustrated with detailed
+    engravings. Price =$1.00=
+
+
+=Aviation Chart. Location of Airplane Power Plant Troubles Made Easy.=
+By Lieut. VICTOR W. PAGE, A.S., S.C.U.S.R.
+
+    A large chart outlining all parts of a typical airplane power
+    plant, showing the points where trouble is apt to occur and
+    suggesting remedies for the common defects. Intended especially
+    for Aviators and Aviation Mechanics on School and Field Duty.
+    Price =50 cents=
+
+
+~BRAZING AND SOLDERING~
+
+
+=Brazing and Soldering.= By JAMES F. HOBART.
+
+    The only book that shows you just how to handle any job of
+    brazing or soldering that comes along; it tells you what mixture
+    to use, how to make a furnace if you need one. Full of valuable
+    kinks. The fifth edition of this book has just been published,
+    and to it much new matter and a large number of tested formulae
+    for all kinds of solders and fluxes have been added.
+    Illustrated. Price =25 cents=
+
+
+~CHARTS~
+
+
+=Aviation Chart. Location of Airplane Power Plant Troubles Made Easy.=
+By Lieut. VICTOR W. PAGE, A.S., S.C.U.S.R.
+
+    A large chart outlining all parts of a typical airplane power
+    plant, showing the points where trouble is apt to occur and
+    suggesting remedies for the common defects. Intended especially
+    for Aviators and Aviation Mechanics on School and Field Duty.
+    Price =50 cents=
+
+
+=Gasoline Engine Troubles Made Easy--A Chart Showing Sectional View of
+Gasoline Engine.= Compiled by Lieut. VICTOR W. PAGE, A.S., S.C.U.S.R.
+
+    It shows clearly all parts of a typical four-cylinder gasoline
+    engine of the four-cycle type. It outlines distinctly all parts
+    liable to give trouble and also details the derangements apt to
+    interfere with smooth engine operation.
+
+    Valuable to students, motorists, mechanics, repairmen,
+    garagemen, automobile salesmen, chauffeurs, motor-boat owners,
+    motor-truck and tractor drivers, aviators, motor-cyclists, and
+    all others who have to do with gasoline power plants.
+
+    It simplifies location of all engine troubles, and while it will
+    prove invaluable to the novice, it can be used to advantage by
+    the more expert. It should be on the walls of every public and
+    private garage, automobile repair shop, club house or school. It
+    can be carried in the automobile or pocket with ease and will
+    insure against loss of time when engine trouble manifests
+    itself.
+
+    This sectional view of engine is a complete review of all motor
+    troubles. It is prepared by a practical motorist for all who
+    motor. No details omitted. Size 25x38 inches. Price =25 cents=
+
+
+=Lubrication of the Motor Car Chassis.=
+
+    This chart presents the plan view of a typical six-cylinder
+    chassis of standard design and all parts are clearly indicated
+    that demand oil, also the frequency with which they must be
+    lubricated and the kind of oil to use. A practical chart for all
+    interested in motor-car maintenance. Size 24x38 inches. Price
+    =25 cents=
+
+
+=Location of Carburetion Troubles Made Easy.=
+
+    This chart shows all parts of a typical pressure feed fuel
+    supply system and gives causes of trouble, how to locate defects
+    and means of remedying them. Size 24x38 inches. Price =25 cents=
+
+
+=Location of Ignition System Troubles Made Easy.=
+
+    In this chart all parts of a typical double ignition system
+    using battery and magneto current are shown and suggestions are
+    given for readily finding ignition troubles and eliminating them
+    when found. Size 24x38 inches. Price =25 cents=
+
+
+=Location of Cooling and Lubrication System Faults.=
+
+    This composite chart shows a typical automobile power plant
+    using pump circulated water-cooling system and the most popular
+    lubrication method. Gives suggestions for curing all overheating
+    and loss of power faults due to faulty action of the oiling or
+    cooling group. Size 24x38 inches. Price =25 Cents=
+
+
+=Motorcycle Troubles Made Easy--A Chart Showing Sectional View of
+Single-Cylinder Gasoline Engine.= Compiled by VICTOR W. PAGE, M.S.A.E.
+
+    This chart simplifies location of all power-plant troubles, and
+    will prove invaluable to all who have to do with the operation,
+    repair or sale of motorcycles. No details omitted. Size 25x38
+    inches. Price =25 cents=
+
+
+=Location of Ford Engine Troubles Made Easy.= Compiled by VICTOR W.
+PAGE, M.S.A.E.
+
+    This shows clear sectional views depicting all portions of the
+    Ford power plant and auxiliary groups. It outlines clearly all
+    parts of the engine, fuel supply system, ignition group and
+    cooling system, that are apt to give trouble, detailing all
+    derangements that are liable to make an engine lose power, start
+    hard or work irregularly. This chart is valuable to students,
+    owners, and drivers, as it simplifies location of all engine
+    faults. Of great advantage as an instructor for the novice, it
+    can be used equally well by the more expert as a work of
+    reference and review. It can be carried in the toolbox or pocket
+    with ease and will save its cost in labor eliminated the first
+    time engine trouble manifests itself. Prepared with special
+    reference to the average man's needs and is a practical review
+    of all motor troubles because it is based on the actual
+    experience of an automobile engineer-mechanic with the mechanism
+    the chart describes. It enables the non-technical owner or
+    operator of a Ford car to locate engine derangements by
+    systematic search, guided by easily recognized symptoms instead
+    of by guesswork. It makes the average owner independent of the
+    roadside repair shop when touring. Must be seen to be
+    appreciated. Size 25x38 inches. Printed on heavy bond paper.
+    Price =25 cents=
+
+=Modern Submarine Chart--with Two Hundred Parts Numbered and Named.=
+
+    A cross-section view, showing clearly and distinctly all the
+    interior of a Submarine of the latest type. You get more
+    information from this chart, about the construction and
+    operation of a Submarine, than in any other way. No details
+    omitted--everything is accurate and to scale. It is absolutely
+    correct in every detail, having been approved by Naval
+    Engineers. All the machinery and devices fitted in a modern
+    Submarine Boat are shown, and to make the engraving more readily
+    understood all the features are shown in operative form, with
+    Officers and Men in the act of performing the duties assigned to
+    them in service conditions. This CHART IS REALLY AN ENCYCLOPEDIA
+    OF A SUBMARINE. It is educational and worth many times its cost.
+    Mailed in a Tube for =25 Cents=
+
+
+=Box Car Chart.=
+
+    A chart showing the anatomy of a box car, having every part of
+    the car numbered and its proper name given in a reference list.
+    Price =25 Cents=
+
+
+=Gondola Car Chart.=
+
+    A chart showing the anatomy of a gondola car, having every part
+    of the car numbered and its proper reference name given in a
+    reference list. Price =25 Cents=
+
+
+=Passenger-Car Chart.=
+
+    A chart showing the anatomy of a passenger-car, having every
+    part of the car numbered and its proper name given in a
+    reference list =25 Cents=
+
+
+=Steel Hopper Bottom Coal Car.=
+
+    A chart showing the anatomy of a steel Hopper Bottom Coal Car,
+    having every part of the car numbered and its proper name given
+    in a reference list. Price =25 Cents=
+
+
+=Tractive Power Chart.=
+
+    A chart whereby you can find the tractive power or drawbar pull
+    of any locomotive without making a figure. Shows what cylinders
+    are equal, how driving wheels and steam pressure affect the
+    power. What sized engine you need to exert a given drawbar pull
+    or anything you desire in this line. Price =50 Cents=
+
+
+=Horse-Power Chart.=
+
+    Shows the horse-power of any stationary engine without
+    calculation. No matter what the cylinder diameter of stroke, the
+    steam pressure of cut-off, the revolutions, or whether
+    condensing or non-condensing, it's all there. Easy to use,
+    accurate, and saves time and calculations. Especially useful to
+    engineers and designers. Price =50 Cents=
+
+
+=Boiler Room Chart.= By GEO. L. FOWLER.
+
+    A chart--size 14x28 inches--showing in isometric perspective the
+    mechanisms belonging in a modern boiler room. The various parts
+    are shown broken or removed, so that the internal construction
+    is fully illustrated. Each part is given a reference number, and
+    these, with the corresponding name, are given in a glossary
+    printed at the sides. This chart is really a dictionary of the
+    boiler room--the names of more than 200 parts being given. Price
+    =25 Cents=
+
+
+~COKE~
+
+
+=Modern Coking Practice, Including Analysis of Materials and Products.=
+
+By J. E. CHRISTOPHER and T. H. BYROM.
+
+    This, the standard work on the subject, has just been revised.
+    It is a practical work for those engaged in Coke manufacture and
+    the recovery of By-products. Fully illustrated with folding
+    plates. It has been the aim of the authors, in preparing this
+    book, to produce one which shall be of use and benefit to those
+    who are associated with, or interested in, the modern
+    developments of the industry. Among the Chapters contained in
+    Volume I are: Introduction; Classification of Fuels; Impurities
+    of Coals; Coal Washing; Sampling and Valuation of Coals, etc.;
+    Power of Fuels; History of Coke Manufacture; Developments in the
+    Coke Oven Design; Recent Types of Coke Ovens; Mechanical
+    Appliances at Coke Ovens; Chemical and Physical Examination of
+    Coke. Volume II covers fully the subject of By-Products. Price,
+    per volume =$3.00 net=
+
+
+~COMPRESSED AIR~
+
+
+=Compressed Air in All Its Applications.= By GARDNER D. HISCOX.
+
+    This is the most complete book on the subject of Air that has
+    ever been issued, and its thirty-five chapters include about
+    every phase of the subject one can think of. It may be called an
+    encyclopedia of compressed air. It is written by an expert, who,
+    in its 665 pages, has dealt with the subject in a comprehensive
+    manner, no phase of it being omitted. Includes the physical
+    properties of air from a vacuum to its highest pressure, its
+    thermodynamics, compression, transmission and uses as a motive
+    power, in the Operation of Stationary and Portable Machinery, in
+    Mining, Air Tools, Air Lifts, Pumping of Water, Acids, and Oils;
+    the Air Blast for Cleaning and Painting the Sand Blast and its
+    Work, and the Numerous Appliances in which Compressed Air is a
+    Most Convenient and Economical Transmitter of Power for
+    Mechanical Work, Railway Propulsion, Refrigeration, and the
+    Various Uses to which Compressed Air has been applied. Includes
+    forty-four tables of the physical properties of air, its
+    compression, expansion, and volumes required for various kinds
+    of work, and a list of patents on compressed air from 1875 to
+    date. Over 500 illustrations, 5th Edition, revised and enlarged.
+
+    Cloth bound. Price =$5.00=
+
+    Half Morocco. Price =$6.50=
+
+
+~CONCRETE~
+
+
+=Concrete Workers' Reference Books. A Series of Popular Handbooks for
+Concrete Users.= Prepared by A. A. HOUGHTON =50 cents=
+
+    _The author, in preparing this Series, has not only treated on
+    the usual types of construction, but explains and illustrates
+    molds and systems that are not patented, but which are equal in
+    value and often superior to those restricted by patents. These
+    molds are very easily and cheaply constructed and embody
+    simplicity, rapidity of operation, and the most successful
+    results in the molded concrete. Each of these books is fully
+    illustrated, and the subjects are exhaustively treated in plain
+    English._
+
+
+=Concrete Wall Forms.= By A. A. HOUGHTON.
+
+    A new automatic wall clamp is illustrated with working drawings.
+    Other types of wall forms, clamps, separators, etc., are also
+    illustrated and explained. (No. 1 of Series) Price =50 cents=
+
+
+=Concrete Floors and Sidewalks.= By A. A. HOUGHTON.
+
+    The molds for molding squares, hexagonal and many other styles
+    of mosaic floor and sidewalk blocks are fully illustrated and
+    explained. (No. 2 of Series) Price =50 cents=
+
+
+=Practical Concrete Silo Construction.= By A. A. HOUGHTON.
+
+    Complete working drawings and specifications are given for
+    several styles of concrete silos, with illustrations of molds
+    for monolithic and block silos. The tables, data, and
+    information presented in this book are of the utmost value in
+    planning and constructing all forms of concrete silos. (No. 3 of
+    Series) Price =50 cents=
+
+
+=Molding Concrete Chimneys, Slate and Hoof Tiles.= By A. A. HOUGHTON.
+
+    The manufacture of all types of concrete slate and roof tile is
+    fully treated. Valuable data on all forms of reinforced concrete
+    roofs are contained within its pages. The construction of
+    concrete chimneys by block and monolithic systems is fully
+    illustrated and described. A number of ornamental designs of
+    chimney construction with molds are shown in this valuable
+    treatise. (No. 4 of Series.) Price =50 cents=
+
+
+=Molding and Curing Ornamental Concrete.= By A. A. HOUGHTON.
+
+    The proper proportions of cement and aggregates for various
+    finishes, also the method of thoroughly mixing and placing in
+    the molds, are fully treated. An exhaustive treatise on this
+    subject that every concrete worker will find of daily use and
+    value. (No. 5 of Series.) Price =50 cents=
+
+
+=Concrete Monuments, Mausoleums and Burial Vaults.= By A. A. HOUGHTON.
+
+    The molding of concrete monuments to imitate the most expensive
+    cut stone is explained in this treatise with working drawings of
+    easily built molds. Cutting inscriptions and designs are also
+    fully treated. (No. 6 of Series.) Price =50 cents=
+
+
+=Molding Concrete Bathtubs, Aquariums and Natatoriums.= By A. A.
+HOUGHTON.
+
+    Simple molds and instruction are given for molding many styles
+    of concrete bathtubs, swimming-pools, etc. These molds are
+    easily built and permit rapid and successful work. (No. 7 of
+    Series.) Price =50 cents=
+
+
+=Concrete Bridges, Culverts and Sewers.= By A. A. HOUGHTON.
+
+    A number of ornamental concrete bridges with illustrations of
+    molds are given. A collapsible center or core for bridges,
+    culverts and sewers is fully illustrated with detailed
+    instructions for building. (No. 8 of Series.) Price =50 cents=
+
+
+=Constructing Concrete Porches.= By A. A. HOUGHTON.
+
+    A number of designs with working drawings of molds are fully
+    explained so any one can easily construct different styles of
+    ornamental concrete porches without the purchase of expensive
+    molds. (No. 9 of Series.) Price =50 cents=
+
+
+=Molding Concrete Flower-Pots, Boxes, Jardinieres, Etc.= By A. A.
+HOUGHTON.
+
+    The molds for producing many original designs of flower-pots,
+    urns, flower-boxes, jardinieres, etc., are fully illustrated and
+    explained, so the worker can easily construct and operate same.
+    (No. 10 of Series.) Price =50 cents=
+
+
+=Molding Concrete Fountains and Lawn Ornaments.= By A. A. HOUGHTON.
+
+    The molding of a number of designs of lawn seats, curbing,
+    hitching posts, pergolas, sun dials and other forms of
+    ornamental concrete for the ornamentation of lawns and gardens,
+    is fully illustrated and described. (No. 11 of Series.) Price
+    =50 cents=
+
+
+=Concrete from Sand Molds.= By A. A. HOUGHTON.
+
+    A Practical Work treating on a process which has heretofore been
+    held as a trade secret by the few who possessed it, and which
+    will successfully mold every and any class of ornamental
+    concrete work. The process of molding concrete with sand molds
+    is of the utmost practical value, possessing the manifold
+    advantages of a low cost of molds, the ease and rapidity of
+    operation, perfect details to all ornamental designs, density
+    and increased strength of the concrete, perfect curing of the
+    work without attention and the easy removal of the molds
+    regardless of any undercutting the design may have. 192 pages.
+    Fully illustrated Price =$2.00=
+
+
+=Ornamental Concrete without Molds.= By A. A. HOUGHTON.
+
+    The process for making ornamental concrete without molds has
+    long been held as a secret, and now, for the first time, this
+    process is given to the public. The book reveals the secret and
+    is the only book published which explains a simple, practical
+    method whereby the concrete worker is enabled, by employing wood
+    and metal templates of different designs, to mold or model in
+    concrete any Cornice, Archivolt, Column, Pedestal, Base Cap, Urn
+    or Pier in a monolithic form--right upon the job. These may be
+    molded in units or blocks and then built up to suit the
+    specifications demanded. This work is fully illustrated, with
+    detailed engravings. Price =$2.00=
+
+
+=Concrete for the Farm and in the Shop.= By H. COLIN CAMPBELL, C.E.,
+E.M.
+
+    "Concrete for the Farm and in the Shop" is a new book from cover
+    to cover, illustrating and describing in plain, simple language
+    many of the numerous applications of concrete within the range
+    of the home worker. Among the subjects treated are: Principles
+    of Reinforcing; Methods of Protecting Concrete so as to Insure
+    Proper Hardening; Home-made Mixers; Mixing by Hand and Machine;
+    Form Construction, Described and Illustrated by Drawings and
+    Photographs; Construction of Concrete Walls and Fences; Concrete
+    Fence Posts; Concrete Gate Posts; Corner Posts; Clothes Line
+    Posts; Grape Arbor Posts; Tanks; Troughs; Cisterns; Hog Wallows;
+    Feeding Floors and Barnyard Pavements; Foundations; Well Curbs
+    and Platforms; Indoor Floors; Sidewalks; Steps; Concrete Hotbeds
+    and Cold Frames; Concrete Slab Roofs; Walls for Buildings;
+    Repairing Leaks in Tanks and Cisterns; and all topics associated
+    with these subjects as bearing upon securing the best results
+    from concrete are dwelt upon at sufficient length in plain
+    every-day English so that the inexperienced person desiring to
+    undertake a piece of concrete construction can, by following the
+    directions set forth in this book, secure 100 per cent. success
+    every time. A number of convenient and practical tables for
+    estimating quantities, and some practical examples, are also
+    given. (5x7.) 149 pages. 51 illustrations. Price =75 cents=
+
+
+=Popular Handbook for Cement and Concrete Users.= By MYRON H. LEWIS.
+
+    This is a concise treatise of the principles and methods
+    employed in the manufacture and use of cement in all classes of
+    modern works. The author has brought together in this work all
+    the salient matter of interest to the user of concrete and its
+    many diversified products. The matter is presented in logical
+    and systematic order, clearly written, fully illustrated and
+    free from involved mathematics. Everything of value to the
+    concrete user is given, including kinds of cement employed in
+    construction, concrete architecture, inspection and testing,
+    waterproofing, coloring and painting, rules, tables, working and
+    cost data. The book comprises thirty-three chapters, as follow:
+    Introductory. Kinds of Cement and How They are Made. Properties.
+    Testing and Requirements of Hydraulic Cement. Concrete and Its
+    Properties. Sand, Broken Stone and Gravel for Concrete. How to
+    Proportion the Materials. How to Mix and Place Concrete. Forms
+    of Concrete Construction. The Architectural and Artistic
+    Possibilities of Concrete. Concrete Residences. Mortars,
+    Plasters and Stucco, and How to Use Them. The Artistic Treatment
+    of Concrete Surfaces. Concrete Building Blocks. The Making of
+    Ornamental Concrete. Concrete Pipes, Fences, Posts, etc.
+    Essential Features and Advantages of Reenforced Concrete. How to
+    Design Reenforced Concrete Beams, Slabs and Columns.
+    Explanations of the Methods and Principles in Designing
+    Reenforced Concrete, Beams and Slabs. Systems of Reenforcement
+    Employed. Reenforced Concrete in Factory and General Building
+    Construction. Concrete in Foundation Work. Concrete Retaining
+    Walls, Abutments and Bulkheads. Concrete Arches and Arch
+    Bridges. Concrete Beam and Girder Bridges. Concrete in Sewerage
+    and Draining Works. Concrete Tanks, Dams and Reservoirs.
+    Concrete Sidewalks, Curbs and Pavements. Concrete in Railroad
+    Construction. The Utility of Concrete on the Farm. The
+    Waterproofing of Concrete Structures. Grout of Liquid Concrete
+    and Its Use. Inspection of Concrete Work. Cost of Concrete Work.
+    Some of the special features of the book are: 1.--The Attention
+    Paid to the Artistic and Architectural Side of Concrete Work.
+    2.--The Authoritative Treatment of the Problem of Waterproofing
+    Concrete. 3.--An Excellent Summary of the Rules to be Followed
+    in Concrete Construction. 4.--The Valuable Cost Data and Useful
+    Tables given. A valuable Addition to the Library of Every Cement
+    and Concrete User. Price =$2.50=
+
+    WHAT IS SAID OF THIS BOOK:
+
+    "The field of Concrete Construction is well covered and the
+    matter contained is well within the understanding of any
+    person."--_Engineering-Contracting._
+
+    "Should be on the bookshelves of every contractor, engineer, and
+    architect in the land."--_National Builder._
+
+
+=Waterproofing Concrete.= By MYRON H. LEWIS.
+
+    Modern Methods of Waterproofing Concrete and Other Structures. A
+    condensed statement of the Principles, Rules, and Precautions to
+    be Observed in Waterproofing and Dampproofing Structures and
+    Structural Materials. Paper binding. Illustrated. Price =50
+    cents=
+
+
+~DICTIONARIES~
+
+
+=Aviation Terms, Termes D'Aviation, English-French, French-English.=
+Compiled by Lieuts. VICTOR W. PAGE, A.S., S.C.U.S.R., and PAUL
+MONTARIOL, of the French Flying Corps, on duty on Signal Corps Aviation
+School, Mineola, L. I.
+
+    The lists contained are confined to essentials, and special
+    folding plates are included to show all important airplane
+    parts. The lists are divided in four sections as follows:
+    1.--Flying Field Terms. 2.--The Airplane. 3.--The Engine.
+    4.--Tools and Shop Terms.
+
+    A complete, well illustrated volume intended to facilitate
+    conversation between English-speaking and French aviators. A
+    very valuable book for all who are about to leave for duty
+    overseas.
+
+    Approved for publication by Major W. G. Kilner, S.C., U.S.C.O.
+    Signal Corps Aviation School, Hazelhurst Field, Mineola, L. I.
+    This book should be in every Aviator's and Mechanic's Kit for
+    ready reference. 128 pages, fully illustrated, with detailed
+    engravings. Price =$1.00=
+
+
+=Standard Electrical Dictionary.= By T. O'CONOR SLOANE.
+
+    An indispensable work to all interested in electrical science.
+    Suitable alike for the student and professional. A practical
+    handbook of reference containing definitions of about 5,000
+    distinct words, terms and phrases. The definitions are terse and
+    concise; and include every term used in electrical science.
+    Recently issued. An entirely new edition. Should be in the
+    possession of all who desire to keep abreast with the progress
+    of this branch of science. Complete, concise and convenient. 682
+    pages, 393 illustrations. Price =$3.00=
+
+
+~DIES--METAL WORK~
+
+
+=Dies: Their Construction and Use for the Modern Working of Sheet
+Metals.= By J. V. WOODWORTH.
+
+    A most useful book, and one which should be in the hands of all
+    engaged in the press working of metals; treating on the
+    Designing, Constructing, and Use of Tools, Fixtures and Devices,
+    together with the manner in which they should be used in the
+    Power Press, for the cheap and rapid production of the great
+    variety of sheet-metal articles now in use. It is designed as a
+    guide to the production of sheet-metal parts at the minimum of
+    cost with the maximum of output. The hardening and tempering of
+    Press tools and the classes of work which may be produced to the
+    best advantage by the use of dies in the power press are fully
+    treated. Its 515 illustrations show dies, press fixtures and
+    sheet-metal working devices, the descriptions of which are so
+    clear and practical that all metal-working mechanics will be
+    able to understand how to design, construct and use them. Many
+    of the dies and press fixtures treated were either constructed
+    by the author or under his supervision. Others were built by
+    skilful mechanics and are in use in large sheet-metal
+    establishments and machine shops. 6th Revised and Enlarged
+    Edition. Price =$3.00=
+
+
+=Punches, Dies and Tools for Manufacturing in Presses.= By J. V.
+WOODWORTH.
+
+    This work is a companion volume to the author's elementary work
+    entitled "Dies: Their Construction and Use." It does not go into
+    the details of die-making to the extent of the author's previous
+    book, but gives a comprehensive review of the field of
+    operations carried on by presses. A large part of the
+    information given has been drawn from the author's personal
+    experience. It might well be termed an Encyclopedia of
+    Die-Making, Punch-Making, Die-Sinking, Sheet-Metal Working, and
+    Making of Special Tools, Sub-presses, Devices and Mechanical
+    Combinations for Punching, Cutting, Bending, Forming, Piercing,
+    Drawing, Compressing and Assembling Sheet-Metal Parts, and also
+    Articles of other Materials in Machine Tools. 2d Edition. Price
+    =$4.00=
+
+
+=Drop Forging, Die-Sinking and Machine-Forming of Steel.= By J. V.
+WOODWORTH.
+
+    This is a practical treatise on Modern Shop Practice, Processes,
+    Methods, Machine Tools, and Details treating on the Hot and Cold
+    Machine-Forming of Steel and Iron into Finished Shapes: together
+    with Tools, Dies, and Machinery involved in the manufacture of
+    Duplicate Forgings and Interchangeable Hot and Cold Pressed
+    Parts from Bar and Sheet Metal. This book fills a demand of long
+    standing for information regarding drop-forgings, die-sinking
+    and machine-forming of steel and the shop practice involved, as
+    it actually exists in the modern drop-forging shop. The
+    processes of die-sinking and force-making, which are thoroughly
+    described and illustrated in this admirable work, are rarely to
+    be found explained in such a clear and concise manner as is here
+    set forth. The process of die-sinking relates to the engraving
+    or sinking of the female or lower dies, such as are used for
+    drop-forgings, hot and cold machine-forging, swedging, and the
+    press working of metals. The process of force-making relates to
+    the engraving or raising of the male or upper dies used in
+    producing the lower dies for the press-forming and
+    machine-forging of duplicate parts of metal.
+
+    In addition to the arts above mentioned the book contains
+    explicit information regarding the drop-forging and hardening
+    plants, designs, conditions, equipment, drop hammers, forging
+    machines, etc., machine forging, hydraulic forging, autogenous
+    welding and shop practice. The book contains eleven chapters,
+    and the information contained in these chapters is just what
+    will prove most valuable to the forged-metal worker. All
+    operations described in the work are thoroughly illustrated by
+    means of perspective half-tones and outline sketches of the
+    machinery employed. 300 detailed illustrations. Price =$2.50=
+
+
+~DRAWING--SKETCHING PAPER~
+
+
+=Practical Perspective.= By RICHARDS and COLVIN.
+
+    Shows just how to make all kinds of mechanical drawings in the
+    only practical perspective isometric. Makes everything plain, so
+    that any mechanic can understand a sketch or drawing in this
+    way. Saves time in the drawing room, and mistakes in the shops.
+    Contains practical examples of various classes of work. 4th
+    Edition. Price =50 cents=
+
+
+=Linear Perspective Self-Taught.= By HERMAN T. C. KRAUS.
+
+    This work gives the theory and practice of linear perspective,
+    as used in architectural, engineering and mechanical drawings.
+    Persons taking up the study of the subject by themselves will be
+    able, by the use of the instruction given, to readily grasp the
+    subject, and by reasonable practice become good perspective
+    draftsmen. The arrangement of the book is good; the plate is on
+    the left-hand, while the descriptive text follows on the
+    opposite page, so as to be readily referred to. The drawings are
+    on sufficiently large scale to show the work clearly and are
+    plainly figured. There is included a self-explanatory chart
+    which gives all information necessary for the thorough
+    understanding of perspective. This chart alone is worth many
+    times over the price of the book. 2d Revised and Enlarged
+    Edition. Price =$2.50=
+
+
+=Self-Taught Mechanical Drawing and Elementary Machine Design.= By F. L.
+SYLVESTER, M.E., Draftsman, with additions by ERIK OBERG, associate
+editor of "Machinery."
+
+    This is a practical treatise on Mechanical Drawing and Machine
+    Design, comprising the first principles of geometric and
+    mechanical drawing, workshop mathematics, mechanics, strength of
+    materials and the calculations and design of machine details.
+    The author's aim has been to adapt this treatise to the
+    requirements of the practical mechanic and young draftsman and
+    to present the matter in as clear and concise a manner as
+    possible. To meet the demands of this class of students,
+    practically all the important elements of machine design have
+    been dealt with, and in addition algebraic formulas have been
+    explained, and the elements of trigonometry treated in the
+    manner best suited to the needs of the practical man. The book
+    is divided into 20 chapters, and in arranging the material,
+    mechanical drawing, pure and simple, has been taken up first, as
+    a thorough understanding of the principles of representing
+    objects facilitates the further study of mechanical subjects.
+    This is followed by the mathematics necessary for the solution
+    of the problems in machine design which are presented later, and
+    a practical introduction to theoretical mechanics and the
+    strength of materials. The various elements entering into
+    machine design, such as cams, gears, sprocket-wheels, cone
+    pulleys, bolts, screws, couplings, clutches, shafting and
+    fly-wheels, have been treated in such a way as to make possible
+    the use of the work as a text-book for a continuous course of
+    study. It is easily comprehended and assimilated even by
+    students of limited previous training. 330 pages, 215
+    engravings. Price =$2.00=
+
+
+=A New Sketching Paper.=
+
+    A new specially ruled paper to enable you to make sketches or
+    drawings in isometric perspective without any figuring or
+    fussing. It is being used for shop details as well as for
+    assembly drawings, as it makes one sketch do the work of three,
+    and no workman can help seeing just what is wanted.
+
+    Pads of 40 sheets, 6x9 inches.    Price     =25 cents=
+    Pads of 40 sheets, 9x12 inches.   Price     =50 cents=
+    40 sheets, 12x18 inches.          Price        =$1.00=
+
+
+~ELECTRICITY~
+
+
+=Arithmetic of Electricity.= By Prof. T. O'CONOR SLOANE.
+
+    A practical treatise on electrical calculations of all kinds
+    reduced to a series of rules, all of the simplest forms, and
+    involving only ordinary arithmetic; each rule illustrated by one
+    or more practical problems, with detailed solution of each one.
+    This book is classed among the most useful works published on
+    the science of electricity, covering as it does the mathematics
+    of electricity in a manner that will attract the attention of
+    those who are not familiar with algebraical formulas. 20th
+    Edition. 160 pages. Price =$1.00=
+
+
+=Commutator Construction.= By WM. BAXTER, JR.
+
+    The business end of any dynamo or motor of the direct current
+    type is the commutator. This book goes into the designing,
+    building, and maintenance of commutators, shows how to locate
+    troubles and how to remedy them; everyone who fusses with
+    dynamos needs this. 4th Edition. Price =25 cents=
+
+
+=Dynamo Building for Amateurs, or How to Construct a Fifty-Watt Dynamo.=
+By ARTHUR J. WEED, Member of N. Y. Electrical Society.
+
+    A practical treatise showing in detail the construction of a
+    small dynamo or motor, the entire machine work of which can be
+    done on a small foot lathe. Dimensioned working drawings are
+    given for each piece of machine work, and each operation is
+    clearly described. This machine, when used as a dynamo, has an
+    output of fifty watts; when used as a motor it will drive a
+    small drill press or lathe. It can be used to drive a sewing
+    machine on any and all ordinary work. The book is illustrated
+    with more than sixty original engravings, showing the actual
+    construction of the different parts. Among the contents are
+    chapters on: 1. Fifty-Watt Dynamo. 2. Side Bearing Rods. 3.
+    Field Punching. 4. Bearings. 5. Commutator. 6. Pulley. 7. Brush
+    Holders. 8. Connection Board. 9. Armature Shaft. 10. Armature.
+    11. Armature Winding. 12. Field Winding. 13. Connecting and
+    starting.
+
+    Paper.   Price     =50 Cents=
+    Cloth.   Price        =$1.00=
+
+
+=Electric Bells.= By M. B. SLEEPER.
+
+    A complete treatise for the practical worker in Installing,
+    Operating and Testing Bell Circuits, Burglar Alarms,
+    Thermostats, and other apparatus used with Electric Bells.
+
+    Both the electrician and the experimenter will find in this book
+    new material which is essential in their work. Tools, bells,
+    batteries, unusual circuits, burglar alarms, annunciator
+    systems, thermostats, circuit breakers, time alarms, and other
+    apparatus used in bell circuits are described from the
+    standpoints of their application, construction and repair. The
+    detailed instruction for building the apparatus will appeal to
+    the experimenter particularly.
+
+    The practical worker will find the chapter on Wiring,
+    Calculation of Wire Sizes and Magnet Winding, Upkeep of Systems,
+    and the Location of Faults, of the greatest value in their work.
+    Among the chapters are: Tools and Materials for Bell Work; How
+    and Why Bell Work; Batteries for Small Installations; Making
+    Bells and Push Buttons; Wiring Bell Systems; Construction of
+    Annunciators and Signals; Burglary Alarms and Auxiliary
+    Apparatus; More Elaborate Bell Systems; Finding Faults and
+    Remedying Them. 124 pages, fully illustrated. Price =50 cents=
+
+
+=Electric Lighting and Heating Pocket Book.= By SYDNEY F. WALKER.
+
+    This book puts in convenient form useful information regarding
+    the apparatus which is likely to be attached to the mains of an
+    electrical company. Tables of units and equivalents are included
+    and useful electrical laws and formulas are stated. 438 pages,
+    300 engravings. Bound in leather. Pocket book form. Price
+    =$3.00=
+
+
+=Electric Wiring, Diagrams and Switchboards.= By NEWTON HARRISON, with
+additions by THOMAS POPPE.
+
+    A thoroughly practical treatise covering the subject of Electric
+    Wiring in all its branches, deluding explanations and diagrams
+    which are thoroughly explicit and greatly simplify the subject.
+    Practical every-day problems in wiring are presented and the
+    method of obtaining intelligent results clearly shown. Only
+    arithmetic is used. Ohm's law is given a simple explanation with
+    reference to wiring for direct and alternating currents. The
+    fundamental principle of drop of potential in circuits is shown
+    with its various applications. The simple circuit is developed
+    with the position of mains, feeders and branches; their
+    treatment as a part of a wiring plan and their employment in
+    house wiring clearly illustrated. Some simple facts about
+    testing are included in connection with the wiring. Molding and
+    conduit work are given careful consideration; and switchboards
+    are systematically treated, built up and illustrated, showing
+    the purpose they serve, for connection with the circuits, and to
+    shunt and compound wound machines. The simple principles of
+    switchboard construction, the development of the switchboard,
+    the connections of the various instruments, including the
+    lightning arrester, are also plainly set forth.
+
+    Alternating current wiring is treated, with explanations of the
+    power factor, conditions calling for various sizes of wire, and
+    a simple way of obtaining the sizes for single-phase, two-phase
+    and three-phase circuits. This is the only complete work issued
+    showing and telling you what you should know about direct and
+    alternating current wiring. It is a ready reference. The work is
+    free from advanced technicalities and mathematics, arithmetic
+    being used throughout. It is in every respect a handy,
+    well-written, instructive, comprehensive volume on wiring for
+    the wireman, foreman, contractor, or electrician. 2nd Revised
+    Edition. 303 pages, 130 illustrations. Price =$1.50=
+
+
+=Electric Furnaces and their Industrial Applications.= By J. WRIGHT.
+
+    This is a book which will prove of interest to many classes of
+    people: the manufacturer who desires to know what product can be
+    manufactured successfully in the electric furnace, the chemist
+    who wishes to post himself on the electro-chemistry, and the
+    student of science who merely looks into the subject from
+    curiosity. New, Revised and Enlarged Edition. 320 pages. Fully
+    illustrated, cloth. Price =$3.00=
+
+
+=Electric Toy Making, Dynamo Building, and Electric Motor Construction.=
+By Prof. T. O'CONOR SLOANE.
+
+    This work treats of the making at home of electrical toys,
+    electrical apparatus, motors, dynamos, and instruments in
+    general, and is designed to bring within the reach of young and
+    old the manufacture of genuine and useful electrical appliances.
+    The work is especially designed for amateurs and young folks.
+
+    Thousands of our young people are daily experimenting, and
+    busily engaged in making electrical toys and apparatus of
+    various kinds. The present work is just what is wanted to give
+    the much needed information in a plain, practical manner, with
+    illustrations to make easy the carrying out of the work. 20th
+    Edition. Price =$1.00=
+
+
+=Practical Electricity.= By Prof. T. O'CONOR SLOANE.
+
+    This work of 768 pages was previously known as Sloane's
+    Electricians' Hand Book, and is intended for the practical
+    electrician who has to make things go. The entire field of
+    electricity is covered within its pages. Among some of the
+    subjects treated are: The Theory of the Electric Current and
+    Circuit, Electro-Chemistry, Primary Batteries, Storage
+    Batteries, Generation and Utilization of Electric Powers,
+    Alternating Current, Armature Winding, Dynamos and Motors, Motor
+    Generators, Operation of the Central Station Switchboards,
+    Safety Appliances, Distribution of Electric Light and Power,
+    Street Mains, Transformers, Arc and Incandescent Lighting,
+    Electric Measurements, Photometry, Electric Railways, Telephony,
+    Bell-Wiring, Electric-Plating, Electric Heating, Wireless
+    Telegraphy, etc. It contains no useless theory; everything is to
+    the point. It teaches you just what you want to know about
+    electricity. It is the standard work published on the subject.
+    Forty-one chapters, 556 engravings. Price =$2.50=
+
+
+=Electricity Simplified.= By Prof. T. O'CONOR SLOANE.
+
+    The object of "Electricity Simplified" is to make the subject as
+    plain as possible and to show what the modern conception of
+    electricity is; to show how two plates of different metal,
+    immersed in acid, can send a message around the globe; to
+    explain how a bundle of copper wire rotated by a steam engine
+    can be the agent in lighting our streets; to tell what the volt,
+    ohm and ampere are, and what high and low tension mean; and to
+    answer the questions that perpetually arise in the mind in this
+    age of electricity. 13th Edition. 172 pages. Illustrated. Price
+    =$1.00=
+
+
+=House Wiring.= By THOMAS W. POPPE.
+
+    This work describes and illustrates the actual installation of
+    Electric Light Wiring, the manner in which the work should be
+    done, and the method of doing it. The book can be conveniently
+    carried in the pocket. It is intended for the Electrician,
+    Helper and Apprentice. It solves all Wiring Problems and
+    contains nothing that conflicts with the rulings of the National
+    Board of Fire Underwriters. It gives just the information
+    essential to the Successful Wiring of a Building. Among the
+    subjects treated are: Locating the Meter. Panel-Boards.
+    Switches. Plug Receptacles. Brackets. Ceiling Fixtures. The
+    Meter Connections. The Feed Wires. The Steel Armored Cable
+    System. The Flexible Steel Conduit System. The Ridig Conduit
+    System. A digest of the National Board of Fire Underwriters'
+    rules relating to metallic wiring systems. Various switching
+    arrangements explained and diagrammed. The easiest method of
+    testing the Three- and Four-way circuits explained. The
+    grounding of all metallic wiring systems and the reason for
+    doing so shown and explained. The insulation of the metal parts
+    of lamp fixtures and the reason for the same described and
+    illustrated. 125 pages. 2nd Edition, revised and enlarged. Fully
+    illustrated. Flexible cloth. Price =50 cents=
+
+
+=How to Become a Successful Electrician.= By Prof. T. O'CONOR SLOANE.
+
+    Every young man who wishes to become a successful electrician
+    should read this book. It tells in simple language the surest
+    and easiest way to become a successful electrician. The studies
+    to be followed, methods of work, field of operation and the
+    requirements of the successful electrician are pointed out and
+    fully explained. Every young engineer will find this an
+    excellent stepping stone to more advanced works on electricity
+    which he must master before success can be attained. Many young
+    men become discouraged at the very outstart by attempting to
+    read and study books that are far beyond their comprehension.
+    This book serves as the connecting link between the rudiments
+    taught in the public schools and the real study of electricity.
+    It is interesting from cover to cover. 18th Revised Edition,
+    just issued. 205 pages. Illustrated. Price =$1.00=
+
+
+=Management of Dynamos.= By LUMMIS-PATERSON.
+
+    A handbook of theory and practice. This work is arranged in
+    three parts. The first part covers the elementary theory of the
+    dynamo. The second part, the construction and action of the
+    different classes of dynamos in common use are described; while
+    the third part relates to such matters as affect the practical
+    management and working of dynamos and motors. 4th Edition. 292
+    pages, 117 illustrations. Price =$1.50=
+
+
+=Standard Electrical Dictionary.= By T. O'CONOR SLOANE.
+
+    An indispensable work to all interested in electrical science.
+    Suitable alike for the student and professional. A practical
+    handbook of reference containing definitions of about 5,000
+    distinct words, terms and phrases. The definitions are terse and
+    concise and include every term used in electrical science.
+    Recently issued. An entirely new edition. Should be in the
+    possession of all who desire to keep abreast with the progress
+    of this branch of science. In its arrangement and typography the
+    book is very convenient. The word or term defined is printed in
+    black-faced type, which readily catches the eye, while the body
+    of the page is in smaller but distinct type. The definitions are
+    well worded, and so as to be understood by the non-technical
+    reader. The general plan seems to be to give an exact, concise
+    definition, and then amplify and explain in a more popular way.
+    Synonyms are also given, and references to other words and
+    phrases are made. A very complete and accurate index of fifty
+    pages is at the end of the volume; and as this index contains
+    all synonyms, and as all phrases are indexed in every reasonable
+    combination of words, reference to the proper place in the body
+    of the book is readily made. It is difficult to decide how far a
+    book of this character is to keep the dictionary form, and to
+    what extent it may assume the encyclopedia form. For some
+    purposes, concise, exactly worded definitions are needed; for
+    other purposes, more extended descriptions are required. This
+    book seeks to satisfy both demands, and does it with
+    considerable success. 682 pages, 393 illustrations. 12th
+    Edition. Price =$3.00=
+
+
+=Storage Batteries Simplified.= By VICTOR W. PAGE, M.E.
+
+    A complete treatise on storage battery operating principles,
+    repairs and applications. The greatly increasing application of
+    storage batteries in modern engineering and mechanical work has
+    created a demand for a book that will consider this subject
+    completely and exclusively. This is the most thorough and
+    authoritative treatise ever published on this subject. It is
+    written in easily understandable, non-technical language so that
+    any one may grasp the basic principles of storage battery action
+    as well as their practical industrial applications. All electric
+    and gasoline automobiles use storage batteries. Every automobile
+    repairman, dealer or salesman should have a good knowledge of
+    maintenance and repair of these important elements of the motor
+    car mechanism. This book not only tells how to charge, care for
+    and rebuild storage batteries but also outlines all the
+    industrial uses. Learn how they run street cars, locomotives and
+    factory trucks. Get an understanding of the important functions
+    they perform in submarine boats, isolated lighting plants,
+    railway switch and signal systems, marine applications, etc.
+    This book tells how they are used in central station standby
+    service, for starting automobile motors and in ignition systems.
+    Every practical use of the modern storage battery is outlined in
+    this treatise. 320 pages, fully illustrated. Price =$1.50=
+
+
+=Switchboards.= By WILLIAM BAXTER, JR.
+
+    This book appeals to every engineer and electrician who wants to
+    know the practical side of things. It takes up all sorts and
+    conditions of dynamos, connections and circuits, and shows by
+    diagram and illustration just how the switchboard should be
+    connected. Includes direct and alternating current boards, also
+    those for arc lighting, incandescent and power circuits. Special
+    treatment on high voltage boards for power transmission. 2nd
+    Edition. 190 pages, Illustrated. Price =$1.50=
+
+
+=Telephone Construction, Installation, Wiring, Operation and
+Maintenance.= By W. H. RADCLIFFE and H. C. CUSHING.
+
+    This book is intended for the amateur, the wireman, or the
+    engineer who desires to establish a means of telephonic
+    communication between the rooms of his home, office, or shop. It
+    deals only with such things as may be of use to him rather than
+    with theories.
+
+    Gives the principles of construction and operation of both the
+    Bell and Independent instruments; approved methods of installing
+    and wiring them; the means of protecting them from lightning and
+    abnormal currents; their connection together for operation as
+    series or bridging stations; and rules for their inspection and
+    maintenance. Line wiring and the wiring and operation of special
+    telephone systems are also treated. Intricate mathematics are
+    avoided, and all apparatus, circuits and systems are thoroughly
+    described. The appendix contains definitions of units and terms
+    used in the text. Selected wiring tables, which are very
+    helpful, are also included. Among the subjects treated are
+    Construction, Operation, and Installation of Telephone
+    Instruments; Inspection and Maintenance of Telephone
+    Instruments; Telephone Line Wiring; Testing Telephone Line Wires
+    and Cables; Wiring and Operation of Special Telephone Systems,
+    etc. 2nd Edition, Revised and Enlarged. 223 pages, 154
+    illustrations. Price =$1.00=
+
+
+=Wireless Telegraphy and Telephony Simply Explained.= By ALFRED P.
+MORGAN.
+
+    This is undoubtedly one of the most complete and comprehensible
+    treatises on the subject ever published, and a close study of
+    its pages will enable one to master all the details of the
+    wireless transmission of messages. The author has filled a
+    long-felt want and has succeeded in furnishing a lucid,
+    comprehensible explanation in simple language of the theory and
+    practice of wireless telegraphy and telephony.
+
+    Among the contents are: Introductory; Wireless Transmission and
+    Reception--The Aerial System, Earth Connections--The
+    Transmitting Apparatus, Spark Coils and Transformers,
+    Condensers, Helixes, Spark Gaps, Anchor Gaps, Aerial
+    Switches--The Receiving Apparatus, Detectors, etc.--Tuning and
+    Coupling, Tuning Coils, Loose Couplers, Variable Condensers,
+    Directive Wave Systems--Miscellaneous Apparatus, Telephone
+    Receivers, Range of Stations, Static Interference--Wireless
+    Telephones, Sound and Sound Waves, The Vocal Cords and
+    Ear--Wireless Telephone, How Sounds Are Changed into Electric
+    Waves--Wireless Telephones, The Apparatus--Summary. 154 pages,
+    156 engravings. Price =$1.00=
+
+
+=Wiring a House.= By HERBERT PRATT.
+
+    Shows a house already built; tells just how to start about
+    wiring it; where to begin; what wire to use; how to run it
+    according to Insurance Rules; in fact, just the information you
+    need. Directions apply equally to a shop. 4th Edition. Price =25
+    cents=
+
+
+~FACTORY MANAGEMENT, ETC.~
+
+
+=Modern Machine Shop Construction, Equipment and Management.= By O. E.
+PERRIGO, M.E.
+
+    The only work published that describes the modern machine shop
+    or manufacturing plant from the time the grass is growing on the
+    site intended for it until the finished product is shipped. By a
+    careful study of its thirty-two chapters the practical man may
+    economically build, efficiently equip, and successfully manage
+    the modern machine shop or manufacturing establishment. Just the
+    book needed by those contemplating the erection of modern shop
+    buildings, the rebuilding and reorganization of old ones, or the
+    introduction of modern shop methods, time and cost systems. It
+    is a book written and illustrated by a practical shop man for
+    practical shop men who are too busy to read _theories_ and want
+    _facts_. It is the most complete all-around book of its kind
+    ever published. It is a practical book for practical men, from
+    the apprentice in the shop to the president in the office. It
+    minutely describes and illustrates the most simple and yet the
+    most efficient time and cost system yet devised. 2nd Revised and
+    Enlarged Edition, just issued. 384 pages, 219 illustrations.
+    Price =$5.00=
+
+
+~FUEL~
+
+
+=Combustion of Coal and the Prevention of Smoke.= By WM. M. BARR.
+
+    This book has been prepared with special reference to the
+    generation of heat by the combustion of the common fuels found
+    in the United States, and deals particularly with the conditions
+    necessary to the economic and smokeless combustion of bituminous
+    coals in Stationary and Locomotive Steam Boilers.
+
+    The presentation of this important subject is systematic and
+    progressive. The arrangement of the book is in a series of
+    practical questions to which are appended accurate answers,
+    which describe in language, free from technicalities, the
+    several processes involved in the furnace combustion of American
+    fuels; it clearly states the essential requisites for perfect
+    combustion, and points out the best methods for furnace
+    construction for obtaining the greatest quantity of heat from
+    any given quality of coal. Nearly 350 pages, fully illustrated.
+    Price =$1.00=
+
+
+=Smoke Prevention and Fuel Economy.= By BOOTH and KERSHAW.
+
+    A complete treatise for all interested in smoke prevention and
+    combustion, being based on the German work of Ernst Schmatolla,
+    but it is more than a mere translation of the German treatise,
+    much being added. The authors show as briefly as possible the
+    principles of fuel combustion, the methods which have been and
+    are at present in use, as well as the proper scientific methods
+    for obtaining all the energy in the coal and burning it without
+    smoke. Considerable space is also given to the examination of
+    the waste gases, and several of the representative English and
+    American mechanical stoker and similar appliances are described.
+    The losses carried away in the waste gases are thoroughly
+    analyzed and discussed in the Appendix, and abstracts are also
+    here given of various patents on combustion apparatus. The book
+    is complete and contains much of value to all who have charge of
+    large plants. 194 pages. Illustrated. Price =$2.50=
+
+
+~GAS ENGINES AND GAS~
+
+
+=Gas, Gasoline and Oil Engines.= By GARDNER D. HISCOX. Revised by VICTOR
+W. PAGE, M.E.
+
+    Just issued New 1918 Edition, Revised and Enlarged. Every user
+    of a gas engine needs this book. Simple, instructive and right
+    up-to-date. The only complete work on the subject. Tells all
+    about internal combustion engineering, treating exhaustively on
+    the design, construction and practical application of all forms
+    of gas, gasoline, kerosene and crude petroleum-oil engines.
+    Describes minutely all auxiliary systems, such as lubrication,
+    carburetion and ignition. Considers the theory and management of
+    all forms of explosive motors for stationary and marine work,
+    automobiles, aeroplanes and motor-cycles. Includes also Producer
+    Gas and Its Production. Invaluable instructions for all
+    students, gas-engine owners, gas-engineers, patent experts,
+    designers, mechanics, draftsmen and all having to do with the
+    modern power. Illustrated by over 400 engravings, many specially
+    made from engineering drawings, all in correct proportion. 650
+    pages, 435 engravings. Price =$2.50 net=
+
+
+=The Gasoline Engine on the Farm: Its Operation, Repair and Uses.= By
+XENO W. PUTNAM.
+
+    This is a practical treatise on the Gasoline and Kerosene Engine
+    intended for the man who wants to know just how to manage his
+    engine and how to apply it to all kinds of farm work to the best
+    advantage.
+
+    This book abounds with hints and helps for the farm and
+    suggestions for the home and house-wife. There is so much of
+    value in this book that it is impossible to adequately describe
+    it in such small space. Suffice to say that it is the kind of a
+    book every farmer will appreciate and every farm home ought to
+    have. Includes selecting the most suitable engine for farm work,
+    its most convenient and efficient installation, with chapters on
+    troubles, their remedies, and how to avoid them. The care and
+    management of the farm tractor in plowing, harrowing, harvesting
+    and road grading are fully covered; also plain directions are
+    given for handling the tractor on the road. Special attention is
+    given to relieving farm life of its drudgery by applying power
+    to the disagreeable small tasks which must otherwise be done by
+    hand. Many home made contrivances for cutting wood, supplying
+    kitchen, garden, and barn with water, loading, hauling and
+    unloading hay, delivering grain to the bins or the feed trough
+    are included; also full directions for making the engine milk
+    the cows, churn, wash, sweep the house and clean the windows,
+    etc. Very fully illustrated with drawings of working parts and
+    cuts showing Stationary, Portable and Tractor Engines doing all
+    kinds of farm work. All money-making farms utilize power. Learn
+    how to utilize power by reading the pages of this book. It is an
+    aid to the result getter, invaluable to the up-to-date farmer,
+    student, blacksmith, implement dealer and, in fact, all who can
+    apply practical knowledge of stationary gasoline engines or gas
+    tractors to advantage. 530 pages. Nearly 180 engravings. Price
+    =$2.00=
+
+    WHAT IS SAID OF THIS BOOK:
+
+    "Am much pleased with the book and find it to be very complete
+    and up-to-date. I will heartily recommend it to students and
+    farmers whom I think would stand in need of such a work, as I
+    think it is an exceptionally good one."--_N. S. Gardiner_, Prof.
+    in Charge, Clemson Agr. College of S. C.; Dept. of Agri. and
+    Agri. Exp. Station, Clemson College, S. C.
+
+    "I feel that Mr. Putnam's book covers the main points which a
+    farmer should know."--_R. T. Burdick_, Instructor in Agronomy,
+    University of Vermont, Burlington, Vt.
+
+
+=Gasoline Engines: Their Operation, Use and Care.= By A. HYATT VERRILL.
+
+    The simplest, latest and most comprehensive popular work
+    published on Gasoline Engines, describing what the Gasoline
+    Engine is; its construction and operation; how to install it;
+    how to select it; how to use it and how to remedy troubles
+    encountered. Intended for Owners, Operators and Users of
+    Gasoline Motors of all kinds. This work fully describes and
+    illustrates the various types of Gasoline Engines used in Motor
+    Boats, Motor Vehicles and Stationary Work. The parts,
+    accessories and appliances are described with chapters on
+    ignition, fuel, lubrication, operation and engine troubles.
+    Special attention is given to the care, operation and repair of
+    motors, with useful hints and suggestions on emergency repairs
+    and makeshifts. A complete glossary of technical terms and an
+    alphabetically arranged table of troubles and their symptoms
+    form most valuable and unique features of this manual. Nearly
+    every illustration in the book is original, having been made by
+    the author. Every page is full of interest and value. A book
+    which you cannot afford to be without. 275 pages, 152 specially
+    made engravings. Price =$1.50=
+
+
+=Gas Engine Construction, or How to Build a Half-horsepower Gas Engine.=
+By PARSELL and WEED.
+
+    A practical treatise of 300 pages describing the theory and
+    principles of the action of Gas Engines of various types and the
+    design and construction of a half-horsepower Gas Engine, with
+    illustrations of the work in actual progress, together with the
+    dimensioned working drawings, giving clearly the sizes of the
+    various details; for the student, the scientific investigator,
+    and the amateur mechanic. This book treats of the subject more
+    from the standpoint of practice than that of theory. The
+    principles of operation of Gas Engines are clearly and simply
+    described, and then the actual construction of a half-horsepower
+    engine is taken up, step by step, showing in detail the making
+    of the Gas Engine. 3rd Edition. 300 pages. Price =$2.50=
+
+
+=How to Run and Install Two- and Four-Cycle Marine Gasoline Engines.= By
+C. VON CULIN.
+
+    Revised and enlarged edition just issued. The object of this
+    little book is to furnish a pocket instructor for the beginner,
+    the busy man who uses an engine for pleasure or profit, but who
+    does not have the time or inclination for a technical book, but
+    simply to thoroughly understand how to properly operate, install
+    and care for his own engine. The index refers to each trouble,
+    remedy, and subject alphabetically. Being a quick reference to
+    find the cause, remedy and prevention for troubles, and to
+    become an expert with his own engine. Pocket size. Paper
+    binding. Price =25 cents=
+
+
+=Modern Gas Engines and Producer Gas Plants.= By R. E. MATHOT.
+
+    A guide for the gas engine designer, user, and engineer in the
+    construction, selection, purchase, installation, operation, and
+    maintenance of gas engines. More than one book on gas engines
+    has been written, but not one has thus far even encroached on
+    the field covered by this book. Above all, Mr. Mathot's work is
+    a practical guide. Recognizing the need of a volume that would
+    assist the gas engine user in understanding thoroughly the motor
+    upon which he depends for power, the author has discussed his
+    subject without the help of any mathematics and without
+    elaborate theoretical explanations. Every part of the gas engine
+    is described in detail, tersely, clearly, with a thorough
+    understanding of the requirements of the mechanic. Helpful
+    suggestions as to the purchase of an engine, its installation,
+    care, and operation, form a most valuable feature of the work.
+    320 pages, 175 detailed illustrations. Price =$2.50=
+
+
+=The Modern Gas Tractor.= By VICTOR W. PAGE, M. E.
+
+    A complete treatise describing all types and sizes of gasoline,
+    kerosene and oil tractors. Considers design and construction
+    exhaustively, gives complete instructions for care, operation
+    and repair, outlines all practical applications on the road and
+    in the field. The best and latest work on farm tractors and
+    tractor power plants. A work needed by farmers, students,
+    blacksmiths, mechanics, salesmen, implement dealers, designers
+    and engineers. 2nd Edition, Revised. 504 pages, 228
+    illustrations, 3 folding plates. Price =$2.00=
+
+
+~GEARING AND CAMS~
+
+
+=Bevel Gear Tables.= By D. AG. ENGSTROM.
+
+    A book that will at once commend itself to mechanics and
+    draftsmen. Does away with all the trigonometry and fancy
+    figuring on bevel gears, and makes it easy for anyone to lay
+    them out or make them just right. There are 36 full-page tables
+    that show every necessary dimension for all sizes or
+    combinations you're apt to need. No puzzling, figuring or
+    guessing. Gives placing distance, all the angles (including
+    cutting angles), and the correct cutter to use. A copy of this
+    prepares you for anything in the bevel-gear line. 3rd Edition.
+    66 pages. Price =$1.00=
+
+
+=Change Gear Devices.= By OSCAR E. PERRIGO.
+
+    A practical book for every designer, draftsman, and mechanic
+    interested in the invention and development of the devices for
+    feed changes on the different machines requiring such mechanism.
+    All the necessary information on this subject is taken up,
+    analyzed, classified, sifted, and concentrated for the use of
+    busy men who have not the time to go through the masses of
+    irrelevant matter with which such a subject is usually
+    encumbered and select such information as will be useful to
+    them.
+
+    It shows just what has been done, how it has been done, when it
+    was done, and who did it. It saves time in hunting up patent
+    records and re-inventing old ideas. 88 pages. 3rd Edition. Price
+    =$1.00=
+
+
+=Drafting of Cams.= By LOUIS ROUILLION.
+
+    The laying out of cams is a serious problem unless you know how
+    to go at it right. This puts you on the right road for
+    practically any kind of cam you are likely to run up against.
+    3rd Edition. Price =25 Cents=
+
+
+~HYDRAULICS~
+
+
+=Hydraulic Engineering.= By GARDNER D. HISCOX.
+
+    A treatise on the properties, power, and resources of water for
+    all purposes. Including the measurement of streams, the flow of
+    water in pipes or conduits; the horsepower of falling water,
+    turbine and impact water-wheels, wave motors, centrifugal,
+    reciprocating and air-lift pumps. With 300 figures and diagrams
+    and 36 practical tables. All who are interested in water-works
+    development will find this book a useful one, because it is an
+    entirely practical treatise upon a subject of present importance
+    and cannot fail in having a far-reaching influence, and for this
+    reason should have a place in the working library of every
+    engineer. Among the subjects treated are: Historical Hydraulics;
+    Properties of Water; Measurement of the Flow of Streams; Flow
+    from Sub-surface Orifices and Nozzles; Flow of Water in Pipes;
+    Siphons of Various Kinds; Dams and Great Storage Reservoirs;
+    City and Town Water Supply; Wells and Their Reinforcement;
+    Air-lift Methods of Raising Water; Artesian Wells; Irrigation of
+    Arid Districts; Water Power; Water Wheels; Pumps and Pumping
+    Machinery; Reciprocating Pumps; Hydraulic Power Transmission;
+    Hydraulic Mining; Canals; Ditches; Conduits and Pipe Lines;
+    Marine Hydraulics; Tidal and Sea Wave Power, etc. 320 pages.
+    Price =$4.00=
+
+
+~ICE AND REFRIGERATION~
+
+
+=Pocketbook of Refrigeration and Ice Making.= By A. J. WALLIS-TAYLOR.
+
+    This is one of the latest and most comprehensive reference books
+    published on the subject of refrigeration and cold storage. It
+    explains the properties and refrigerating effect of the
+    different fluids in use, the management of refrigerating
+    machinery and the construction and insulation of cold rooms with
+    their required pipe surface for different degrees of cold;
+    freezing mixtures and non-freezing brines, temperatures of cold
+    rooms for all kinds of provisions, cold storage charges for all
+    classes of goods, ice making and storage of ice, data and
+    memoranda for constant reference by refrigerating engineers,
+    with nearly one hundred tables containing valuable references to
+    every fact and condition required in the installment and
+    operation of a refrigerating plant. New edition just published.
+    Price =$1.50=
+
+
+~INVENTIONS--PATENTS~
+
+
+=Inventors' Manual: How to Make a Patent Pay.=
+
+    This is a book designed as a guide to inventors in perfecting
+    their inventions, taking out their patents and disposing of
+    them. It is not in any sense a Patent Solicitor's Circular nor a
+    Patent Broker's Advertisement. No advertisements of any
+    description appear in the work. It is a book containing a
+    quarter of a century's experience of a successful inventor,
+    together with notes based upon the experience of many other
+    inventors.
+
+    Among the subjects treated in this work are: How to Invent. How
+    to Secure a Good Patent. Value of Good Invention. How to Exhibit
+    an Invention. How to Interest Capital. How to Estimate the Value
+    of a Patent. Value of Design Patents. Value of Foreign Patents.
+    Value of Small Inventions. Advice on Selling Patents. Advice on
+    the Formation of Stock Companies. Advice on the Formation of
+    Limited Liability Companies. Advice on Disposing of Old Patents.
+    Advice as to Patent Attorneys. Advice as to Selling Agents.
+    Forms of Assignments. License and Contracts. State Laws
+    Concerning Patent Rights. 1900 Census of the United States by
+    Counts of Over 10,000 Population. Revised Edition. 120 pages.
+    Price =$1.00=
+
+
+~KNOTS~
+
+
+=Knots, Splices and Rope Work.= By A. HYATT VERRILL.
+
+    This is a practical book giving complete and simple directions
+    for making all the most useful and ornamental knots in common
+    use, with chapters on Splicing, Pointing, Seizing, Serving, etc.
+    This book is fully illustrated with 154 original engravings,
+    which show how each knot, tie or splice is formed, and its
+    appearance when finished. The book will be found of the greatest
+    value to Campers, Yachtsmen, Travelers, Boy Scouts, in fact, to
+    anyone having occasion to use or handle rope or knots for any
+    purpose. The book is thoroughly reliable and practical, and is
+    not only a guide, but a teacher. It is the standard work on the
+    subject. Among the contents are: 1. Cordage, Kinds of Rope.
+    Construction of Rope, Parts of Rope Cable and Bolt Rope.
+    Strength of Rope, Weight of Rope. 2. Simple Knots and Bends.
+    Terms Used in Handling Rope. Seizing Rope. 3. Ties and Hitches.
+    4. Noose, Loops and Mooring Knots. 5. Shortenings, Grommets and
+    Salvages. 6. Lashings, Seizings and Splices. 7. Fancy Knots and
+    Rope Work. 128 pages, 150 original engravings. 2nd Revised
+    Edition. Price =75 cents=
+
+
+~LATHE WORK~
+
+
+=Lathe Design, Construction, and Operation, with Practical Examples of
+Lathe Work.= By OSCAR E. PERRIGO.
+
+    A new, revised edition, and the only complete American work on
+    the subject, written by a man who knows not only how work ought
+    to be done, but who also knows how to do it, and how to convey
+    this knowledge to others. It is strictly up-to-date in its
+    descriptions and illustrations. Lathe history and the relations
+    of the lathe to manufacturing are given; also a description of
+    the various devices for feeds and thread-cutting mechanisms from
+    early efforts in this direction to the present time. Lathe
+    design is thoroughly discussed, including back gearing, driving
+    cones, thread-cutting gears, and all the essential elements of
+    the modern lathe. The classification of lathes is taken up,
+    giving the essential differences of the several types of lathes
+    including, as is usually understood, engine lathes, bench
+    lathes, speed lathes, forge lathes, gap lathes, pulley lathes,
+    forming lathes, multiple-spindle lathes, rapid-reduction lathes,
+    precision lathes, turret lathes, special lathes, electrically
+    driven lathes, etc. In addition to the complete exposition on
+    construction and design, much practical matter on lathe
+    installation, care and operation has been incorporated in the
+    enlarged new edition. All kinds of lathe attachments for
+    drilling, milling, etc., are described and complete instructions
+    are given to enable the novice machinist to grasp the art of
+    lathe operation as well as the principles involved in design. A
+    number of difficult machining operations are described at length
+    and illustrated. The new edition has nearly 500 pages and 350
+    illustrations. Price =$2.50=
+
+    WHAT IS SAID OF THIS BOOK:
+
+    "This is a lathe book from beginning to end, and is just the
+    kind of a book which one delights to consult--a masterly
+    treatment of the subject in hand."--_Engineering News._
+
+    "This work will be of exceptional interest to any one who is
+    interested in lathe practice, as one very seldom sees such a
+    complete treatise on a subject as this is on the
+    lathe."--_Canadian Machinery._
+
+
+=Practical Metal Turning.= By JOSEPH G. HORNER.
+
+    A work of 404 pages, fully illustrated, covering in a
+    comprehensive manner the modern practice of machining metal
+    parts in the lathe, including the regular engine lathe, its
+    essential design, its uses, its tools, its attachments, and the
+    manner of holding the work and performing the operations. The
+    modernized engine lathe, its methods, tools and great range of
+    accurate work. The turret lathe, its tools, accessories and
+    methods of performing its functions. Chapters on special work,
+    grinding, tool holders, speeds, feeds, modern tool steels, etc.
+    Second edition =$3.50=
+
+
+=Turning and Boring Tapers.= By FRED H. COLVIN.
+
+    There are two ways to turn tapers; the right way and one other.
+    This treatise has to do with the right way; it tells you how to
+    start the work properly, how to set the lathe, what tools to use
+    and how to use them, and forty and one other little things that
+    you should know. Fourth edition =25 cents=
+
+
+~LIQUID AIR~
+
+
+=Liquid Air and the Liquefaction of Gases.= By T. O'CONOR SLOANE.
+
+    This book gives the history of the theory, discovery and
+    manufacture of Liquid Air, and contains an illustrated
+    description of all the experiments that have excited the wonder
+    of audiences all over the country. It shows how liquid air, like
+    water, is carried hundreds of miles and is handled in open
+    buckets. It tells what may be expected from it in the near
+    future.
+
+    A book that renders simple one of the most perplexing chemical
+    problems of the century. Startling developments illustrated by
+    actual experiments.
+
+    It is not only a work of scientific interest and authority, but
+    is intended for the general reader, being written in a popular
+    style--easily understood by every one. Second edition. 365
+    pages. Price =$2.00=
+
+
+~LOCOMOTIVE ENGINEERING~
+
+
+=Air-Brake Catechism.= By ROBERT H. BLACKALL.
+
+    This book is a standard text-book. It covers the Westinghouse
+    Air-Brake Equipment, including the No. 5 and the No. 6 E.-T.
+    Locomotive Brake Equipment; the K (Quick Service) Triple Valve
+    for Freight Service; and the Cross-Compound Pump. The operation
+    of all parts of the apparatus is explained in detail, and a
+    practical way of finding their peculiarities and defects, with a
+    proper remedy, is given. It contains 2,000 questions with their
+    answers, which will enable any railroad man to pass any
+    examination on the subject of Air Brakes. Endorsed and used by
+    air-brake instructors and examiners on nearly every railroad in
+    the United States. Twenty-sixth edition. 411 pages, fully
+    illustrated with colored plates and diagrams. Price =$2.00=
+
+
+=American Compound Locomotives.= By FRED H. COLVIN.
+
+    The only book on compounds for the engineman or shopman that
+    shows in a plain, practical way the various features of compound
+    locomotives in use. Shows how they are made, what to do when
+    they break down or balk. Contains sections as follows: A Bit of
+    History. Theory of Compounding Steam Cylinders. Baldwin
+    Two-Cylinder Compound. Pittsburg Two-Cylinder Compound. Rhode
+    Island Compound. Richmond Compound. Rogers Compound. Schenectady
+    Two-Cylinder Compound. Vauclain Compound. Tandem Compounds.
+    Baldwin Tandem. The Colvin-Wightman Tandem. Schenectady Tandem.
+    Balanced Locomotives. Baldwin Balanced Compound. Plans for
+    Balancing. Locating Blows. Breakdowns. Reducing Valves.
+    Drifting. Valve Motion. Disconnecting. Power of Compound
+    Locomotives. Practical Notes.
+
+    Fully illustrated and containing ten special "Duotone" inserts
+    on heavy Plate Paper, showing different types of Compounds. 142
+    pages. Price =$1.00=
+
+
+=Application of Highly Superheated Steam to Locomotives.= By ROBERT
+GARBE.
+
+    A practical book which cannot be recommended too highly to those
+    motive-power men who are anxious to maintain the highest
+    efficiency in their locomotives. Contains special chapters on
+    Generation of Highly Superheated Steam; Superheated Steam and
+    the Two-Cylinder Simple Engine; Compounding and Superheating;
+    Designs of Locomotive Superheaters; Constructive Details of
+    Locomotives Using Highly Superheated Steam. Experimental and
+    Working Results. Illustrated with folding plates and tables.
+    Cloth. Price =$2.50=
+
+
+=Combustion of Coal and the Prevention of Smoke.= By WM. M. BARR.
+
+    This book has been prepared with special reference to the
+    generation of heat by the combustion of the common fuels found
+    in the United States and deals particularly with the conditions
+    necessary to the economic and smokeless combustion of bituminous
+    coal in Stationary and Locomotive Steam Boilers.
+
+    Presentation of this important subject is systematic and
+    progressive. The arrangement of the book is in a series of
+    practical questions to which are appended accurate answers,
+    which describe in language free from technicalities the several
+    processes involved in the furnace combustion of American fuels;
+    it clearly states the essential requisites for perfect
+    combustion, and points out the best methods of furnace
+    construction for obtaining the greatest quantity of heat from
+    any given quality of coal. Nearly 350 pages, fully illustrated.
+    Price =$1.00=
+
+
+=Diary of a Round-House Foreman.= By T. S. REILLY.
+
+    This is the greatest book of railroad experiences ever
+    published. Containing a fund of information and suggestions
+    along the line of handling men, organizing, etc., that one
+    cannot afford to miss. 176 pages. Price =$1.00=
+
+
+=Link Motions, Valves and Valve Setting.= By FRED H. COLVIN, Associate
+Editor of "American Machinist."
+
+    A handy book for the engineer or machinist that clears up the
+    mysteries of valve setting. Shows the different valve gears in
+    use, how they work, and why. Piston and slide valves of
+    different types are illustrated and explained. A book that every
+    railroad man in the motive-power department ought to have.
+    Contains chapters on Locomotive Link Motion, Valve Movements,
+    Setting Slide Valves, Analysis by Diagrams, Modern Practice,
+    Slip of Block, Slice Valves, Piston Valves, Setting Piston
+    Valves, Joy-Allen Valve Gear, Walschaert Valve Gear, Gooch Valve
+    Gear, Alfree-Hubbell Valve Gear, etc., etc. Fully illustrated.
+    Price =50 cents=
+
+
+=Locomotive Boiler Construction.= By FRANK A. KLEINHANS.
+
+    The construction of boilers in general is treated and, following
+    this, the locomotive boiler is taken up in the order in which
+    its various parts go through the shop. Shows all types of
+    boilers used; gives details of construction; practical facts,
+    such as life of riveting, punches and dies; work done per day,
+    allowance for bending and flanging sheets and other data.
+    Including the recent Locomotive Boiler Inspection Laws and
+    Examination Questions with their answers for Government
+    Inspectors. Contains chapters on Laying-Out Work; Flanging and
+    Forging; Punching; Shearing; Plate Planing; General Tables;
+    Finishing Parts; Bending; Machinery Parts; Riveting; Boiler
+    Details; Smoke-Box Details; Assembling and Calking; Boiler-Shop
+    Machinery, etc., etc.
+
+    There isn't a man who has anything to do with boiler work,
+    either new or repair work, who doesn't need this book. The
+    manufacturer, superintendent, foreman and boiler worker--all
+    need it. No matter what the type of boiler, you'll find a mint
+    of information that you wouldn't be without. Over 400 pages,
+    five large folding plates. Price =$3.00=
+
+
+=Locomotive Breakdowns and their Remedies.= By GEO. L. FOWLER. Revised
+by WM. W. WOOD, Air-Brake Instructor. Just issued. Revised pocket
+edition.
+
+    It is out of the question to try and tell you about every
+    subject that is covered in this pocket edition of Locomotive
+    Breakdowns. Just imagine all the common troubles that an
+    engineer may expect to happen some time, and then add all of the
+    unexpected ones, troubles that could occur, but that you have
+    never thought about, and you will find that they are all treated
+    with the very best methods of repair. Walschaert Locomotive
+    Valve Gear Troubles, Electric Headlight Troubles, as well as
+    Questions and Answers on the Air Brake are all included. 312
+    pages. 8th Revised Edition. Fully illustrated. Price =$1.00=
+
+
+=Locomotive Catechism.= By ROBERT GRIMSHAW.
+
+    The revised edition of "Locomotive Catechism," by Robert
+    Grimshaw, is a New Book from Cover to Cover. It contains twice
+    as many pages and double the number of illustrations of previous
+    editions. Includes the greatest amount of practical information
+    ever published on the construction and management of modern
+    locomotives. Specially Prepared Chapters on the Walschaert
+    Locomotive Valve Gear, the Air-Brake Equipment and the Electric
+    Headlight are given.
+
+    It commends itself at once to every Engineer and Fireman, and to
+    all who are going in for examination or promotion. In plain
+    language, with full, complete answers, not only all the
+    questions asked by the examining engineer are given, but those
+    which the young and less experienced would ask the veteran, and
+    which old hands ask as "stickers." It is a veritable
+    Encyclopedia of the Locomotive, is entirely free from
+    mathematics, easily understood and thoroughly up to date.
+    Contains over 4,000 Examination Questions with their Answers.
+    825 pages, 437 illustrations, and 3 folding plates. 28th Revised
+    Edition. Price =$2.50=
+
+
+=Practical Instructor and Reference Book for Locomotive Firemen and
+Engineers.= By CHAS. F. LOCKHART.
+
+    An entirely new book on the Locomotive. It appeals to every
+    railroad man, as it tells him how things are done and the right
+    way to do them. Written by a man who has had years of practical
+    experience in locomotive shops and on the road firing and
+    running. The information given in this book cannot be found in
+    any other similar treatise. Eight hundred and fifty-one
+    questions with their answers are included, which will prove
+    specially helpful to those preparing for examination. Practical
+    information on: The Construction and Operation of Locomotives,
+    Breakdowns and their Remedies, Air Brakes and Valve Gears. Rules
+    and Signals are handled in a thorough manner. As a book of
+    reference it cannot be excelled. The book is divided into six
+    parts, as follows: 1. The Fireman's Duties. 2. General
+    Description of the Locomotive. 3. Breakdowns and their Remedies.
+    4. Air Brakes. 5. Extracts from Standard Rules. 6. Questions for
+    Examination. The 851 questions have been carefully selected and
+    arranged. These cover the examinations required by the different
+    railroads. 368 pages, 88 illustrations. Price =$1.50=
+
+
+=Prevention of Railroad Accidents, or Safety in Railroading.= By GEORGE
+BRADSHAW.
+
+    This book is a heart-to-heart talk with Railroad Employees,
+    dealing with facts, not theories, and showing the men in the
+    ranks, from every-day experience, how accidents occur and how
+    they may be avoided. The book is illustrated with seventy
+    original photographs and drawings showing the safe and unsafe
+    methods of work. No visionary schemes, no ideal pictures. Just
+    Plain Facts and Practical Suggestions are given. Every railroad
+    employee who reads the book is a better and safer man to have in
+    railroad service. It gives just the information which will be
+    the means of preventing many injuries and deaths. All railroad
+    employees should procure a copy, read it, and do their part in
+    preventing accidents. 169 pages. Pocket size. Fully illustrated.
+    Price =50 cents=
+
+
+=Train Rule Examinations Made Easy.= By G. E. COLLINGWOOD.
+
+    This is the only practical work on train rules in print. Every
+    detail is covered, and puzzling points are explained in simple,
+    comprehensive language, making it a practical treatise for the
+    Train Dispatcher, Engineman, Trainman, and all others who have
+    to do with the movements of trains. Contains complete and
+    reliable information of the Standard Code of Train Rules for
+    single track. Shows Signals in Colors, as used on the different
+    roads. Explains fully the practical application of train orders,
+    giving a clear and definite understanding of all orders which
+    may be used. The meaning and necessity for certain rules are
+    explained in such a manner that the student may know beyond a
+    doubt the rights conferred under any orders he may receive or
+    the action required by certain rules. As nearly all roads
+    require trainmen to pass regular examinations, a complete set of
+    examination questions, with their answers, are included. These
+    will enable the student to pass the required examinations with
+    credit to himself and the road for which he works. 2nd Edition,
+    Revised. 256 pages, fully illustrated, with Train Signals in
+    Colors. Price =$1.25=
+
+
+=The Walschaert and Other Modern Radial Valve Gears for Locomotives.= By
+WM. W. WOOD.
+
+    If you would thoroughly understand the Walschaert Valve Gear you
+    should possess a copy of this book, as the author takes the
+    plainest form of a steam engine--a stationary engine in the
+    rough, that will only turn its crank in one direction--and from
+    it builds up, with the reader's help, a modern locomotive
+    equipped with the Walschaert Valve Gear, complete. The points
+    discussed are clearly illustrated: Two large folding plates that
+    show the positions of the valves of both inside or outside
+    admission type, as well as the links and other parts of the gear
+    when the crank is at nine different points in its revolution,
+    are especially valuable in making the movement clear. These
+    employ sliding cardboard models which are contained in a pocket
+    in the cover.
+
+    The book is divided into five general divisions, as follows: 1.
+    Analysis of the gear. 2. Designing and erecting the gear. 3.
+    Advantages of the gear. 4. Questions and answers relating to the
+    Walschaert Valve Gear. 5. Setting valves with the Walschaert
+    Valve Gear; the three primary types of locomotive valve motion;
+    modern radial valve gears other than the Walschaert; the Hobart
+    All-free Valve and Valve Gear, with questions and answers on
+    breakdowns; the Baker-Pilliod Valve Gear; the Improved
+    Baker-Pilliod Valve Gear, with questions and answers on
+    breakdowns.
+
+    The questions with full answers given will be especially
+    valuable to firemen and engineers in preparing for an
+    examination for promotion. 245 pages. 3rd Revised Edition. Price
+    =$1.50=
+
+
+=Westinghouse E-T Air-Brake Instruction Pocket Book.= By WM. W. WOOD,
+Air-Brake Instructor.
+
+    Here is a book for the railroad man, and the man who aims to be
+    one. It is without doubt the only complete work published on the
+    Westinghouse E-T Locomotive Brake Equipment. Written by an
+    Air-Brake Instructor who knows just what is needed. It covers
+    the subject thoroughly. Everything about the New Westinghouse
+    Engine and Tender Brake Equipment, including the standard No. 5
+    and the Perfected No. 6 style of brake, is treated in detail.
+    Written in plain English and profusely illustrated with Colored
+    Plates, which enable one to trace the flow of pressures
+    throughout the entire equipment. The best book ever published on
+    the Air Brake. Equally good for the beginner and the advanced
+    engineer. Will pass any one through any examination. It informs
+    and enlightens you on every point. Indispensable to every
+    engineman and trainman.
+
+    Contains examination questions and answers on the E-T equipment.
+    Covering what the E-T Brake is. How it should be operated. What
+    to do when defective. Not a question can be asked of the
+    engineman up for promotion, on either the No. 5 or the No. 6 E-T
+    equipment, that is not asked and answered in the book. If you
+    want to thoroughly understand the E-T equipment get a copy of
+    this book. It covers every detail. Makes Air-Brake troubles and
+    examinations easy. Price =$1.50=
+
+
+~MACHINE-SHOP PRACTICE~
+
+
+=American Tool Making and Interchangeable Manufacturing.= By J. V.
+WOODWORTH.
+
+    A "shoppy" book, containing no theorizing, no problematical or
+    experimental devices. There are no badly proportioned and
+    impossible diagrams, no catalogue cuts, but a valuable
+    collection of drawings and descriptions of devices, the rich
+    fruits of the author's own experience. In its 500-odd pages the
+    one subject only, Tool Making, and whatever relates thereto, is
+    dealt with. The work stands without a rival. It is a complete,
+    practical treatise, on the art of American Tool Making and
+    system of interchangeable manufacturing as carried on to-day in
+    the United States. In it are described and illustrated all of
+    the different types and classes of small tools, fixtures,
+    devices, and special appliances which are in general use in all
+    machine-manufacturing and metal-working establishments where
+    economy, capacity, and interchangeability in the production of
+    machined metal parts are imperative. The science of jig making
+    is exhaustively discussed, and particular attention is paid to
+    drill jigs, boring, profiling and milling fixtures and other
+    devices in which the parts to be machined are located and
+    fastened within the contrivances. All of the tools, fixtures,
+    and devices illustrated and described have been or are used for
+    the actual production of work, such as parts of drill presses,
+    lathes, patented machinery, typewriters, electrical apparatus,
+    mechanical appliances, brass goods, composition parts, mould
+    products, sheet-metal articles, drop-forgings, jewelry, watches,
+    medals, coins, etc. 531 pages. Price =$4.00=
+
+
+=HENLEY'S ENCYCLOPEDIA OF PRACTICAL ENGINEERING AND ALLIED TRADES.=
+EDITED by JOSEPH G. HORNER, A.M.I., M.E.
+
+    This set of five volumes contains about 2,500 pages with
+    thousands of illustrations, including diagrammatic and sectional
+    drawings with full explanatory details. This work covers the
+    entire practice of Civil and Mechanical Engineering. The best
+    known experts in all branches of engineering have contributed to
+    these volumes. The Cyclopedia is admirably well adapted to the
+    needs of the beginner and the self-taught practical man, as well
+    as the mechanical engineer, designer, draftsman, shop
+    superintendent, foreman, and machinist. The work will be found a
+    means of advancement to any progressive man. It is encyclopedic
+    in scope, thorough and practical in its treatment on technical
+    subjects, simple and clear in its descriptive matter, and
+    without unnecessary technicalities or formulae. The articles are
+    as brief as may be and yet give a reasonably clear and explicit
+    statement of the subject, and are written by men who have had
+    ample practical experience in the matters of which they write.
+    It tells you all you want to know about engineering and tells it
+    so simply, so clearly, so concisely, that one cannot help but
+    understand. As a work of reference it is without a peer.
+    Complete set of five volumes, price =$25.00=
+
+
+=The Modern Machinist.= By JOHN T. USHER.
+
+    This is a book, showing by plain description and by profuse
+    engravings made expressly for the work, all that is best, most
+    advanced, and of the highest efficiency in modern machine-shop
+    practice, tools and implements, showing the way by which and
+    through which, as Mr. Maxim says "American machinists have
+    become and are the finest mechanics in the world." Indicating as
+    it does, in every line, the familiarity of the author with every
+    detail of daily experience in the shop, it cannot fail to be of
+    service to any man practically connected with the shaping or
+    finishing of metals.
+
+    There is nothing experimental or visionary about the book, all
+    devices being in actual use and giving good results. It might be
+    called a compendium of shop methods, showing a variety of
+    special tools and appliances which will give new ideas to many
+    mechanics, from the superintendent down to the man at the bench.
+    It will be found a valuable addition to any machinist's library,
+    and should be consulted whenever a new or difficult job is to be
+    done, whether it is boring, milling, turning, or planing, as
+    they are all treated m a practical manner. Fifth edition. 320
+    pages. 250 illustrations. Price =$2.50=
+
+
+=THE WHOLE FIELD OF MECHANICAL MOVEMENTS COVERED BY MR. HISCOX'S TWO
+BOOKS=
+
+    _We publish two books by Gardner D. Hiscox that will keep you
+    from "inventing" things that have been done before, and suggest
+    ways of doing things that you have not thought of before. Many a
+    man spends time and money pondering over some mechanical
+    problem, only to learn, after he has solved the problem, that
+    the same thing has been accomplished and put in practice by
+    others long before. Time and money spent in an effort to
+    accomplish what has already been accomplished are time and money
+    LOST. The whole field of mechanics, every known mechanical
+    movement, and practically every device are covered by these two
+    books. If the thing you want has been invented, it is
+    illustrated in them. If it hasn't been invented, then you'll
+    find in them the nearest things to what you want, some movements
+    or devices that will apply in your case, perhaps; or which will
+    give you a key from which to work. No book or set of books ever
+    published is of more real value to the Inventor, Draftsman, or
+    practical Mechanic than the two volumes described below._
+
+
+=Mechanical Movements, Powers, and Devices.= By GARDNER D. HISCOX.
+
+    This is a collection of 1,890 engravings of different mechanical
+    motions and appliances, accompanied by appropriate text, making
+    it a book of great value to the inventor, the draftsman, and to
+    all readers with mechanical tastes. The book is divided into
+    eighteen sections or chapters, in which the subject-matter is
+    classified under the following heads: Mechanical Powers;
+    Transmission of Power; Measurement of Power; Steam Power; Air
+    Power Appliances; Electric Power and Construction; Navigation
+    and Roads; Gearing; Motion and Devices; Controlling Motion;
+    Horological; Mining; Mill and Factory Appliances; Construction
+    and Devices; Drafting Devices; Miscellaneous Devices, etc. 15th
+    Edition. 400 octavo pages. Price =$3.00=
+
+
+=Mechanical Appliances, Mechanical Movements and Novelties of
+Construction.= By GARDNER D. HISCOX.
+
+    This is a supplementary volume to the one upon mechanical
+    movements. Unlike the first volume, which is more elementary in
+    character, this volume contains illustrations and descriptions
+    of many combinations of motions and of mechanical devices and
+    appliances found in different lines of machinery, each device
+    being shown by a line drawing with a description showing its
+    working parts and the method of operation. From the multitude of
+    devices described and illustrated might be mentioned, in
+    passing, such items as conveyors and elevators, Pony brakes,
+    thermometers, various types of boilers, solar engines, oil-fuel
+    burners, condensers, evaporators, Corliss and other valve gears,
+    governors, gas engines, water motors of various descriptions,
+    air ships, motors and dynamos, automobile and motor bicycles,
+    railway lock signals, car couplers, link and gear motions, ball
+    bearings, breech-block mechanism for heavy guns, and a large
+    accumulation of others of equal importance. One thousand
+    specially made engravings. 396 octavo pages. Fourth edition.
+    Price =$3.00=
+
+
+=Machine-Shop Tools and Shop Practice.= By W. H. VANDERVOORT.
+
+    A work of 555 pages and 673 illustrations, describing in every
+    detail the construction, operation and manipulation of both hand
+    and machine tools. Includes chapters on filing, fitting and
+    scraping surfaces; on drills, reamers, taps and dies; the lathe
+    and its tools: planers, shapers, and their tools; milling
+    machines and cutters; gear cutters and gear cutting; drilling
+    machines and drill work; grinding machines and their work;
+    hardening and tempering; gearing, belting and transmission
+    machinery; useful data and tables. Sixth edition. Price =$3.00=
+
+
+=Machine-Shop Arithmetic.= By COLVIN-CHENEY.
+
+    This is an arithmetic of the things you have to do with daily.
+    It tells you plainly about: how to find areas in figures; how to
+    find surface or volume of balls or spheres; handy ways for
+    calculating; about compound gearing; cutting screw threads on
+    any lathe; drilling for taps; speeds of drills; taps, emery
+    wheels, grindstones, milling cutters, etc.; all about the Metric
+    system with conversion tables; properties of metals; strength of
+    bolts and nuts; decimal equivalent of an inch. All sorts of
+    machine-shop figuring and 1,001 other things, any one of which
+    ought to be worth more than the price of this book to you, as it
+    saves you the trouble of bothering the boss. 6th Edition. 131
+    pages. Price =50 cents=
+
+
+=Modern Machine-Shop Construction, Equipment and Management.= By OSCAR
+E. PERRIGO.
+
+    The only work published that describes the Modern Shop or
+    Manufacturing Plant from the time the grass is growing on the
+    site intended for it until the finished product is shipped. Just
+    the book needed by those contemplating the erection of modern
+    shop buildings, the rebuilding and reorganization of old ones,
+    or the introduction of Modern Shop Methods, time and cost
+    systems. It is a book written and illustrated by a practical
+    shop man for practical shop men who are too busy to read
+    theories and want facts. It is the most complete all-round book
+    of its kind ever published. Second Edition, Revised. 384 large
+    quarto pages. 219 original and specially made illustrations. 2nd
+    Revised and Enlarged Edition. Price =$5.00=
+
+
+=Modern Milling Machines: Their Design, Construction, and Operation.= By
+JOSEPH G. HORNER.
+
+    This book describes and illustrates the Milling Machine and its
+    work in such a plain, clear and forceful manner, and illustrates
+    the subject so clearly and completely, that the up-to-date
+    machinist, student or mechanical engineer cannot afford to do
+    without the valuable information which it contains. It describes
+    not only the early machines of this class, but notes their
+    gradual development into the splendid machines of the present
+    day, giving the design and construction of the various types,
+    forms, and special features produced by prominent manufacturers,
+    American and foreign. 304 pages, 300 illustrations. Cloth. Price
+    =$4.00=
+
+
+="Shop Kinks."= By ROBERT GRIMSHAW.
+
+    A book of 400 pages and 222 illustrations, being entirely
+    different from any other book on machine-shop practice.
+    Departing from conventional style, the author avoids universal
+    or common shop usage and limits his work to showing special ways
+    of doing things better, more cheaply and more rapidly than
+    usual. As a result the advanced methods of representative
+    establishments of the world are placed at the disposal of the
+    reader. This book shows the proprietor where large savings are
+    possible, and how products may be improved. To the employee it
+    holds out suggestions that, properly applied, will hasten his
+    advancement. No shop can afford to be without it. It bristles
+    with valuable wrinkles and helpful suggestions. It will benefit
+    all, from apprentice to proprietor. Every machinist, at any age,
+    should study its pages. Fifth edition. Price =$2.50=
+
+
+=Threads and Thread Cutting.= By COLVIN and STABEL.
+
+    This clears up many of the mysteries of thread-cutting, such as
+    double and triple threads, internal threads, catching threads,
+    use of hobs, etc. Contains a lot of useful hints and several
+    tables. Third edition. Price =25 cents=
+
+
+~MANUAL TRAINING~
+
+
+=Economics of Manual Training.= By LOUIS ROUILLION.
+
+    The only book published that gives just the information needed
+    by all interested in Manual Training, regarding Buildings,
+    Equipment, and Supplies. Shows exactly what is needed for all
+    grades of the work from the Kindergarten to the High and Normal
+    School. Gives itemized lists of everything used in Manual
+    Training Work and tells just what it ought to cost. Also shows
+    where to buy supplies, etc. Contains 174 pages, and is fully
+    illustrated. Second edition. Price =$1.50=
+
+
+~MARINE ENGINEERING~
+
+
+=The Naval Architect's and Shipbuilder's Pocket Book of Formulae, Rules,
+and Tables and Marine Engineer's and Surveyor's Handy Book of
+Reference.= By CLEMENT MACKROW and LLOYD WOOLLARD.
+
+    The eleventh Revised and Enlarged Edition of this most
+    comprehensive work has just been issued. It is absolutely
+    indispensable to all engaged in the Shipbuilding Industry, as it
+    condenses into a compact form all data and formulae that are
+    ordinarily required. The book is completely up to date,
+    including among other subjects a section on Aeronautics. 750
+    pages, limp leather binding. Price =$5.00 net=
+
+
+=Marine Engines and Boilers: Their Design and Construction.= By DR. G.
+BAUER, LESLIE S. ROBERTSON and S. BRYAN DONKIN.
+
+    In the words of Dr. Bauer, the present work owes its origin to
+    an oft felt want of a condensed treatise embodying the
+    theoretical and practical rules used in designing marine engines
+    and boilers. The need of such a work has been felt by most
+    engineers engaged in the construction and working of marine
+    engines, not only by the younger men, but also by those of
+    greater experience. The fact that the original German work was
+    written by the chief engineer of the famous Vulcan Works,
+    Stettin, is in itself a guarantee that this book is in all
+    respects thoroughly up-to-date, and that it embodies all the
+    information which is necessary for the design and construction
+    of the highest types of marine engines and boilers. It may be
+    said that the motive power which Dr. Bauer has placed in the
+    fast German liners that have been turned out of late years from
+    the Stettin Works represent the very best practice in marine
+    engineering of the present day. The work is clearly written,
+    thoroughly systematic, theoretically sound; while the character
+    of the plans, drawings, tables, and statistics is without
+    reproach. The illustrations are careful reproductions from
+    actual working drawings, with some well-executed photographic
+    views of completed engines and boilers. 744 pages, 550
+    illustrations and numerous tables. Cloth. Price =$9.00 net=
+
+
+~MINING~
+
+
+=Ore Deposits, with a Chapter on Hints to Prospectors.= By J. P.
+JOHNSON.
+
+    This book gives a condensed account of the ore deposits at
+    present known in South Africa. It is also intended as a guide to
+    the prospector. Only an elementary knowledge of geology and some
+    mining experience are necessary in order to understand this
+    work. With these qualifications, it will materially assist one
+    in his search for metalliferous mineral occurrences and, so far
+    as simple ores are concerned, should enable one to form some
+    idea of the possibilities of any he may find. Illustrated.
+    Cloth. Price =$2.00=
+
+
+=Practical Coal Mining.= By T. H. COCKIN.
+
+    An important work, containing 428 pages and 213 illustrations,
+    complete with practical details, which will intuitively impart
+    to the reader not only a general knowledge of the principles of
+    coal mining, but also considerable insight into allied subjects.
+    The treatise is positively up-to-date in every instance, and
+    should be in the hands of every colliery engineer, geologist,
+    mine operator, superintendent, foreman, and all others who are
+    interested in or connected with the industry. 3d Edition. Cloth.
+    Price =$2.50=
+
+
+=Physics and Chemistry of Mining.= By T. H. BYROM.
+
+    A practical work for the use of all preparing for examinations
+    in mining or qualifying for colliery managers' certificates. The
+    aim of the author in this excellent book is to place clearly
+    before the reader useful and authoritative data which will
+    render him valuable assistance in his studies. The only work of
+    its kind published. The information incorporated in it will
+    prove of the greatest practical utility to students, mining
+    engineers, colliery managers, and all others who are specially
+    interested in the present-day treatment of mining problems. 160
+    pages, illustrated. Price =$2.00=
+
+
+~PATTERN MAKING~
+
+
+=Practical Pattern Making.= By F. W. BARROWS.
+
+    This book, now in its second edition, is a comprehensive and
+    entirely practical treatise on the subject of pattern making,
+    illustrating pattern work in both wood and metal, and with
+    definite instructions on the use of plaster of paris in the
+    trade. It gives specific and detailed descriptions of the
+    materials used by pattern makers, and describes the tools, both
+    those for the bench and the more interesting machine tools,
+    having complete chapters on the Lathe, the Circular Saw, and the
+    Band Saw. It gives many examples of pattern work, each one fully
+    illustrated and explained with much detail. These examples, in
+    their great variety, offer much that will be found of interest
+    to all pattern makers, and especially to the younger ones, who
+    are seeking information on the more advanced branches of their
+    trade.
+
+    In this second edition of the work will be found much that is
+    new, even to those who have long practised this exacting trade.
+    In the description of patterns as adapted to the Moulding
+    Machine many difficulties which have long prevented the rapid
+    and economical production of castings are overcome; and this
+    great, new branch of the trade is given much space. Stripping
+    plate and stool plate work and the less expensive vibrator, or
+    rapping plate work, are all explained in detail.
+
+    Plain, every-day rules for lessening the cost of patterns, with
+    a complete system of cost keeping, a detailed method of marking,
+    applicable to all branches of the trade, with complete
+    information showing what the pattern is, its specific title, its
+    cost, date of production, material of which it is made, the
+    number of pieces and core-boxes, and its location in the pattern
+    safe, all condensed into a most complete card record, with cross
+    index. The book closes with an original and practical method for
+    the inventory and valuation of patterns. Containing nearly 350
+    pages and 170 illustrations. Price =$2.00=
+
+
+~PERFUMERY~
+
+
+=Perfumes and Cosmetics: Their Preparation and Manufacture.= By G. W.
+ASKINSON, Perfumer.
+
+    A comprehensive treatise, in which there has been nothing
+    omitted that could be of value to the perfumer or manufacturer
+    of toilet preparations. Complete directions for making
+    handkerchief perfumes, smelling-salts, sachets, fumigating
+    pastilles; preparations for the care of the skin, the mouth, the
+    hair, cosmetics, hair dyes and other toilet articles are given,
+    also a detailed description of aromatic substances; their
+    nature, tests of purity, and wholesome manufacture, including a
+    chapter on synthetic products, with formulas for their use. A
+    book of general as well as professional interest, meeting the
+    wants not only of the druggist and perfume manufacturer, but
+    also of the general public. Among the contents are: 1. The
+    History of Perfumery. 2. About Aromatic Substances in General.
+    3. Odors from the Vegetable Kingdom. 4. The Aromatic Vegetable
+    Substances Employed in Perfumery. 5. The Animal Substances Used
+    in Perfumery. 6. The Chemical Products Used in Perfumery. 7. The
+    Extraction of Odors. 8. The Special Characteristics of Aromatic
+    Substances. 9 The Adulteration of Essential Oils and Their
+    Recognition. 10. Synthetic Products. 11. Table of Physical
+    Properties of Aromatic Chemicals. 12. The Essences or Extracts
+    Employed in Perfumery. 13. Directions for Making the Most
+    Important Essences and Extracts. 14. The Division of Perfumery.
+    15. The Manufacture of Handkerchief Perfumes. 16. Formulas for
+    Handkerchief Perfumes. 17. Ammoniacal and Acid Perfumes. 18. Dry
+    Perfumes. 19. Formulas for Dry Perfumes. 20. The Perfumes Used
+    for Fumigation. 21. Antiseptic and Therapeutic Value of
+    Perfumes. 22. Classification of Odors. 23. Some Special
+    Perfumery Products. 24. Hygiene and Cosmetic Perfumery. 25.
+    Preparations for the Care of the Skin. 26. Manufacture of
+    Casein. 27. Formulas for Emulsions. 28. Formulas for Cream. 29.
+    Formulas for Meals, Pastes and Vegetable Milk. 30. Preparations
+    Used for the Hair. 31. Formulas for Hair Tonics and Restorers.
+    32. Pomades and Hair Oils 33. Formulas for the Manufacture of
+    Pomades and Hair Oils. 34. Hair Dyes and Depilatories. 35. Wax
+    Pomades, Bandolines and Brilliantines. 36. Skin Cosmetics and
+    Face Lotions. 37. Preparations for the Nails. 38. Water
+    Softeners and Bath Salts. 39. Preparations for the Care of the
+    Mouth. 40. The Colors Used in Perfumery. 41. The Utensils Used
+    in the Toilet. Fourth edition, much enlarged and brought up to
+    date. Nearly 400 pages, illustrated. Price =$5.00=
+
+    WHAT IS SAID OF THIS BOOK:
+
+    "The most satisfactory work on the subject of Perfumery that we
+    have ever seen."
+
+    "We feel safe in saying that here is a book on Perfumery that
+    will not disappoint you, for it has practical and excellent
+    formulae that are within your ability to prepare readily."
+
+    "We recommend the volume as worthy of confidence, and say that
+    no purchaser will be disappointed in securing from its pages
+    good value for its cost, and a large dividend on the same, even
+    if he should use but one per cent. of its working formulae. There
+    is money in it for every user of its
+    information."--_Pharmaceutical Record._
+
+
+~PLUMBING~
+
+
+=Mechanical Drawing for Plumbers.= By R. M. STARBUCK.
+
+    A concise, comprehensive and practical treatise on the subject
+    of mechanical drawing in its various modern applications to the
+    work of all who are in any way connected with the plumbing
+    trade. Nothing will so help the plumber in estimating and in
+    explaining work to customers and workmen as a knowledge of
+    drawing, and to the workman it is of inestimable value if he is
+    to rise above his position to positions of greater
+    responsibility. Among the chapters contained are: 1. Value to
+    plumber of knowledge of drawing; tools required and their use;
+    common views needed in mechanical drawing. 2. Perspective versus
+    mechanical drawing in showing plumbing construction. 3. Correct
+    and incorrect methods in plumbing drawing; plan and elevation
+    explained. 4. Floor and cellar plans and elevation; scale
+    drawings; use of triangles. 5. Use of triangles; drawing of
+    fittings, traps, etc. 6. Drawing plumbing elevations and
+    fittings. 7. Instructions in drawing plumbing elevations. 8. The
+    drawing of plumbing fixtures; scale drawings. 9. Drawings of
+    fixtures and fittings. 10. Inking of drawings. 11. Shading of
+    drawings. 12. Shading of drawings. 13. Sectional drawings;
+    drawing of threads. 14. Plumbing elevations from architect's
+    plan. 15. Elevations of separate parts of the plumbing system.
+    16. Elevations from the architect's plans. 17. Drawings of
+    detail plumbing connections. 18. Architect's plans and plumbing
+    elevations of residence. 19. Plumbing elevations of residence
+    (_continued_); plumbing plans for cottage. 20. Plumbing
+    elevations; roof connections. 21. Plans and plumbing elevations
+    for six-flat building. 22. Drawing of various parts of the
+    plumbing system; use of scales. 23. Use of architect's scales.
+    24. Special features in the illustrations of country plumbing.
+    25. Drawing of wrought-iron piping, valves, radiators, coils,
+    etc. 26. Drawing of piping to illustrate heating systems. 150
+    illustrations. Price =$1.50=
+
+
+=Modern Plumbing Illustrated.= By R. M. STARBUCK.
+
+    This book represents the highest standard of plumbing work. It
+    has been adopted and used as a reference book by the United
+    States Government in its sanitary work in Cuba, Porto Rico and
+    the Philippines, and by the principal Boards of Health of the
+    United States and Canada.
+
+    It gives connections, sizes and working data for all fixtures
+    and groups of fixtures. It is helpful to the master plumber in
+    demonstrating to his customers and in figuring work. It gives
+    the mechanic and student quick and easy access to the best
+    modern plumbing practice. Suggestions for estimating plumbing
+    construction are contained in its pages. This book represents,
+    in a word, the latest and best up-to-date practice and should be
+    in the hands of every architect, sanitary engineer and plumber
+    who wishes to keep himself up to the minute on this important
+    feature of construction. Contains following chapters, each
+    illustrated with a full-page plate: Kitchen sink, laundry tubs,
+    vegetable wash sink; lavatories, pantry sinks, contents of
+    marble slabs; bath tub, foot and sitz bath, shower bath; water
+    closets, venting of water closets; low-down water closets, water
+    closets operated by flush valves, water closet range; slop sink,
+    urinals, the bidet; hotel and restaurant sink, grease trap;
+    refrigerators, safe wastes, laundry waste, lines of
+    refrigerators, bar sinks, soda fountain sinks; horse stall,
+    frost-proof water closets; connections for S traps, venting;
+    connections for drum traps; soil-pipe connections; supporting of
+    soil pipe; main trap and fresh-air inlet: floor drains and
+    cellar drains, subsoil drainage; water closets and floor
+    connections; local venting; connections for bath rooms;
+    connections for bath rooms, _continued_; examples of poor
+    practice; roughing work ready for test; testing of plumbing
+    systems; method of continuous venting; continuous venting for
+    two-floor work; continuous venting for two lines of fixtures on
+    three or more floors; continuous venting of water closets;
+    plumbing for cottage house; construction for cellar piping;
+    plumbing for residence, use of special fittings; plumbing for
+    two-flat house: plumbing for apartment building, plumbing for
+    double apartment building; plumbing for office building;
+    plumbing for public toilet rooms; plumbing for public toilet
+    rooms, _continued_; plumbing for bath establishment; plumbing
+    for engine house, factory plumbing, automatic flushing for
+    schools, factories, etc.; use of flushing valves; urinals for
+    public toilet rooms; the Durham system, the destruction of pipes
+    by electrolysis; construction of work without use of lead;
+    automatic sewage lift; automatic sump tank; country plumbing;
+    construction of cesspools; septic tank and automatic sewage
+    siphon; water supply for country house; thawing of water mains
+    and service by electricity; double boilers; hot water supply of
+    large buildings; automatic control of hot-water tank;
+    suggestions for estimating plumbing construction. 407 octavo
+    pages, fully illustrated by 57 full-page engravings. Third,
+    revised and enlarged edition, just issued. Price =$4.00=
+
+
+=Standard Practical Plumbing.= By R. M. STARBUCK.
+
+    A complete practical treatise of 450 pages, covering the subject
+    of Modern Plumbing in all its branches, a large amount of space
+    being devoted to a very complete and practical treatment of the
+    subject of Hot Water Supply and Circulation and Range Boiler
+    Work. Its thirty chapters include about every phase of the
+    subject one can think of, making it an indispensable work to the
+    master plumber, the journeyman plumber, and the apprentice
+    plumber, containing chapters on: the plumber's tools; wiping
+    solder; composition and use; joint wiping; lead work; traps;
+    siphonage of traps; venting; continuous venting; house sewer and
+    sewer connections; house drain; soil piping, roughing; main trap
+    and fresh air inlet; floor, yard, cellar drains, rain leaders,
+    etc.; fixture wastes; water closets; ventilation; improved
+    plumbing connections; residence plumbing; plumbing for hotels,
+    schools, factories, stables, etc.; modern country plumbing;
+    filtration of sewage and water supply; hot and cold supply;
+    range boilers; circulation; circulating pipes; range boiler
+    problems; hot water for large buildings; water lift and its use;
+    multiple connections for hot water boilers; heating of radiation
+    by supply system; theory for the plumber; drawing for the
+    plumber. Fully illustrated by 347 engravings. Price =$3.00=
+
+
+~RECIPE BOOK~
+
+
+=Henley's Twentieth Century Book of Recipes, Formulas and Processes.=
+Edited by GARDNER D. HISCOX.
+
+    The most valuable Techno-chemical Formula Book published,
+    including over 10,000 selected scientific, chemical,
+    technological, and practical recipes and processes.
+
+    This is the most complete Book of Formulas ever published,
+    giving thousands of recipes for the manufacture of valuable
+    articles for everyday use. Hints, Helps, Practical Ideas, and
+    Secret Processes are revealed within its pages. It covers every
+    branch of the useful arts and tells thousands of ways of making
+    money, and is just the book everyone should have at his command.
+
+    Modern in its treatment of every subject that properly falls
+    within its scope, the book may truthfully be said to present the
+    very latest formulas to be found in the arts and industries, and
+    to retain those processes which long experience has proven
+    worthy of a permanent record. To present here even a limited
+    number of the subjects which find a place in this valuable work
+    would be difficult. Suffice to say that in its pages will be
+    found matter of intense interest and immeasurably practical
+    value to the scientific amateur and to him who wishes to obtain
+    a knowledge of the many processes used in the arts, trades and
+    manufacture, a knowledge which will render his pursuits more
+    instructive and remunerative. Serving as a reference book to the
+    small and large manufacturer and supplying intelligent seekers
+    with the information necessary to conduct a process, the work
+    will be found of inestimable worth to the Metallurgist, the
+    Photographer, the Perfumer, the Painter, the Manufacturer of
+    Glues, Pastes, Cements, and Mucilages, the Compounder of Alloys,
+    the Cook, the Physician, the Druggist, the Electrician, the
+    Brewer, the Engineer, the Foundryman, the Machinist, the Potter,
+    the Tanner, the Confectioner, the Chiropodist, the Manicurist,
+    the Manufacturer of Chemical Novelties and Toilet Preparations,
+    the Dyer, the Electroplater, the Enameler, the Hat Maker, the
+    Ink Manufacturer, the Optician, the Farmer, the Dairyman, the
+    Paper Maker, the Wood and Metal Worker, the Chandler and Soap
+    Maker, the Veterinary Surgeon, and the Technologist in general.
+
+    A mine of information, and up-to-date in every respect. A book
+    which will prove of value to EVERYONE, as it covers every branch
+    of the Useful Arts. Every home needs this book; every office,
+    every factory, every store, every public and private
+    enterprise--EVERYWHERE--should have a copy. 800 pages. Price
+    =$3.00=
+
+    WHAT IS SAID OF THIS BOOK:
+
+    "Your Twentieth Century Book of Recipes, Formulas, and Processes
+    duly received. I am glad to have a copy of it, and if I could
+    not replace it, money couldn't buy it. It is the best thing of
+    the sort I ever saw." (Signed) M. E. TRUX, Sparta, Wis.
+
+    "There are few persons who would not be able to find in the book
+    some single formula that would repay several times the cost of
+    the book."--_Merchants' Record and Show Window._
+
+    "I purchased your book, 'Henley's Twentieth Century Book of
+    Recipes, Formulas and Processes,' about a year ago and it is
+    worth its weight in _gold_."--WM. H. MURRAY, Bennington, Vt.
+
+    "ONE OF THE WORLD'S MOST USEFUL BOOKS"
+
+    "Some time ago I got one of your 'Twentieth Century Books of
+    Formulas,' and have made my living from it ever since. I am
+    alone since my husband's death with two small children to care
+    for and am trying so hard to support them. I have customers who
+    take from me Toilet Articles I put up, following directions
+    given in the book, and I have found everyone of them to be
+    fine."--MRS. J. H. MCMAKEN, West Toledo, Ohio.
+
+
+~RUBBER~
+
+
+=Rubber Hand Stamps and the Manipulation of India Rubber.= BY T. O'CONOR
+SLOANE.
+
+    This book gives full details on all points, treating in a
+    concise and simple manner the elements of nearly everything it
+    is necessary to understand for a commencement in any branch of
+    the India Rubber Manufacture. The making of all kinds of Rubber
+    Hand Stamps, Small Articles of India Rubber, U. S. Government
+    Composition, Dating Hand Stamps, the Manipulation of Sheet
+    Rubber, Toy Balloons, India Rubber Solutions, Cements,
+    Blackings, Renovating, Varnish, and Treatment for India Rubber
+    Shoes, etc.; the Hektograph Stamp Inks, and Miscellaneous Notes,
+    with a Short Account of the Discovery, Collection and
+    Manufacture of India Rubber, are set forth in a manner designed
+    to be readily understood, the explanations being plain and
+    simple. Including a chapter on Rubber Tire Making and
+    Vulcanizing; also a chapter on the uses of rubber in Surgery and
+    Dentistry. 3rd Revised and Enlarged Edition. 175 pages.
+    Illustrated =$1.00=
+
+
+~SAWS~
+
+
+=Saw Filing and Management of Saws.= By ROBERT GRIMSHAW.
+
+    A practical hand-book on filing, gumming, swaging, hammering,
+    and the brazing of band saws, the speed, work, and power to run
+    circular saws, etc. A handy book for those who have charge of
+    saws, or for those mechanics who do their own filing, as it
+    deals with the proper shape and pitches of saw teeth of all
+    kinds and gives many useful hints and rules for gumming,
+    setting, and filing, and is a practical aid to those who use
+    saws for any purpose. Complete tables of proper shape, pitch,
+    and saw teeth as well as sizes and number of teeth of various
+    saws are included. 3rd Edition, Revised and Enlarged.
+    Illustrated. Price =$1.00=
+
+
+~STEAM ENGINEERING~
+
+
+=American Stationary Engineering.= By W. E. CRANE.
+
+    This book begins at the boiler room and takes in the whole power
+    plant. A plain talk on every-day work about engines, boilers,
+    and their accessories. It is not intended to be scientific or
+    mathematical. All formulas are in simple form so that any one
+    understanding plain arithmetic can readily understand any of
+    them. The author has made this the most practical book in print;
+    has given the results of his years of experience, and has
+    included about all that has to do with an engine room or a power
+    plant. You are not left to guess at a single point. You are
+    shown clearly what to expect under the various conditions; how
+    to secure the best results; ways of preventing "shut downs" and
+    repairs; in short, all that goes to make up the requirements of
+    a good engineer, capable of taking charge of a plant. It's plain
+    enough for practical men and yet of value to those high in the
+    profession.
+
+    A partial list of contents is: The boiler room, cleaning
+    boilers, firing, feeding; pumps, inspection and repair;
+    chimneys, sizes and cost; piping; mason work; foundations;
+    testing cement; pile driving; engines, slow and high speed;
+    valves; valve setting; Corliss engines, setting valves, single
+    and double eccentric; air pumps and condensers; different types
+    of condensers; water needed; lining up; pounds; pins not square
+    in crosshead or crank; engineers' tools; pistons and piston
+    rings; bearing metal; hardened copper; drip pipes from cylinder
+    jacket; belts, how made, care of; oils; greases; testing
+    lubricants; rules and tables, including steam tables; areas of
+    segments; squares and square roots; cubes and cube root; areas
+    and circumferences of circles. Notes on: Brick work; explosions;
+    pumps; pump valves; heaters, economizers; safety valves; lap,
+    lead, and clearance. Has a complete examination for a license,
+    etc., etc. 3rd Edition. 345 pages, illustrated. Price =$2.00=
+
+
+=Engine Runner's Catechism.= By ROBERT GRIMSHAW.
+
+    A practical treatise for the stationary engineer, telling how to
+    erect, adjust, and run the principal steam engines in use in the
+    United States. Describing the principal features of various
+    special and well-known makes of engines: Temper Cut-off,
+    Shipping and Receiving Foundations, Erecting and Starting, Valve
+    Setting, Care and Use, Emergencies, Erecting and Adjusting
+    Special Engines.
+
+    The questions asked throughout the catechism are plain and to
+    the point, and the answers are given in such simple language as
+    to be readily understood by anyone. All the instructions given
+    are complete and up-to-date; and they are written in a popular
+    style, without any technicalities or mathematical formulae. The
+    work is of a handy size for the pocket, clearly and well
+    printed, nicely bound, and profusely illustrated.
+
+    To young engineers this catechism will be of great value,
+    especially to those who may be preparing to go forward to be
+    examined for certificates of competency; and to engineers
+    generally it will be of no little service, as they will find in
+    this volume more really practical and useful information than is
+    to be found anywhere else within a like compass. 387 pages. 7th
+    Edition. Price =$2.00=
+
+
+=Modern Steam Engineering in Theory and Practice.= By GARDNER D. HISCOX.
+
+    This is a complete and practical work issued for Stationary
+    Engineers and Firemen, dealing with the care and management of
+    boilers, engines, pumps, superheated steam, refrigerating
+    machinery, dynamos, motors, elevators, air compressors, and all
+    other branches with which the modern engineer must be familiar.
+    Nearly 200 questions with their answers on steam and electrical
+    engineering, likely to be asked by the Examining Board, are
+    included.
+
+    Among the chapters are: Historical: steam and its properties;
+    appliances for the generation of steam; types of boilers;
+    chimney and its work; heat economy of the feed water; steam
+    pumps and their work; incrustation and its work; steam above
+    atmospheric pressure; flow of steam from nozzles; superheated
+    steam and its work; adiabatic expansion of steam; indicator and
+    its work; steam engine proportions; slide valve engines and
+    valve motion; Corliss engine and its valve gear; compound engine
+    and its theory; triple and multiple expansion engine; steam
+    turbine; refrigeration; elevators and their management; cost of
+    power; steam engine troubles; electric power and electric
+    plants. 487 pages, 405 engravings. 3rd Edition. Price =$3.00=
+
+
+=Steam Engine Catechism.= By ROBERT GRIMSHAW.
+
+    This unique volume of 413 pages is not only a catechism on the
+    question and answer principle but it contains formulas and
+    worked-out answers for all the Steam problems that appertain to
+    operation and management of the Steam Engine. Illustrations of
+    various valves and valve gear with their principles of operation
+    are given. Thirty-four Tables that are indispensable to every
+    engineer and fireman that wishes to be progressive and is
+    ambitious to become master of his calling are within its pages.
+    It is a most valuable instructor in the service of Steam
+    Engineering. Leading engineers have recommended it as a valuable
+    educator for the beginner as well as a reference book for the
+    engineer. It is thoroughly indexed for every detail. Every
+    essential question on the Steam Engine with its answer is
+    contained in this valuable work. 16th Edition. Price =$2.00=
+
+
+=Steam Engineer's Arithmetic.= By COLVIN-CHENEY.
+
+    A practical pocket-book for the steam engineer. Shows how to
+    work the problems of the engine room and shows "why." Tells how
+    to figure horsepower of engines and boilers; area of boilers;
+    has tables of areas and circumferences; steam tables; has a
+    dictionary of engineering terms. Puts you on to all of the
+    little kinks in figuring whatever there is to figure around a
+    power plant. Tells you about the heat unit; absolute zero;
+    adiabatic expansion; duty of engines; factor of safety; and a
+    thousand and one other things; and everything is plain and
+    simple--not the hardest way to figure, but the easiest. 2nd
+    Edition. Price =50 Cents=
+
+
+=Engine Tests and Boiler Efficiencies.= By J. BUCHETTI.
+
+    This work fully describes and illustrates the method of testing
+    the power of steam engines, turbines and explosive motors. The
+    properties of steam and the evaporative power of fuels.
+    Combustion of fuel and chimney draft; with formulas explained or
+    practically computed. 255 pages, 179 illustrations. Price
+    =$3.00=
+
+
+=Horsepower Chart.=
+
+    Shows the horsepower of any stationary engine without
+    calculation. No matter what the cylinder diameter of stroke, the
+    steam pressure of cut-off, the revolutions, or whether
+    condensing or non-condensing, it's all there. Easy to use.
+    accurate, and saves time and calculations. Especially useful to
+    engineers and designers. Price =50 Cents=
+
+
+~STEAM HEATING AND VENTILATION~
+
+
+=Practical Steam, Hot-Water Heating and Ventilation.= By A. G. KING.
+
+    This book is the standard and latest work published on the
+    subject and has been prepared for the use of all engaged in the
+    business of steam, hot-water heating, and ventilation. It is an
+    original and exhaustive work. Tells how to get heating
+    contracts, how to install heating and ventilating apparatus, the
+    best business methods to be used, with "Tricks of the Trade" for
+    shop use. Rules and data for estimating radiation and cost and
+    such tables and information as make it an indispensable work for
+    everyone interested in steam, hot-water heating, and
+    ventilation. It describes all the principal systems of steam,
+    hot-water, vacuum, vapor, and vacuum-vapor heating, together
+    with the new accelerated systems of hot-water circulation,
+    including chapters on up-to-date methods of ventilation and the
+    fan or blower system of heating and ventilation. Containing
+    chapters on: I. Introduction. II. Heat. III. Evolution of
+    artificial heating apparatus. IV. Boiler surface and settings.
+    V. The chimney flue. VI. Pipe and fittings. VII. Valves, various
+    kinds. VIII. Forms of radiating surfaces. IX. Locating of
+    radiating surfaces. X. Estimating radiation. XI. Steam-heating
+    apparatus XII. Exhaust-steam heating. XIII. Hot-water heating.
+    XIV. Pressure systems of hot-water work. XV. Hot-water
+    appliances. XVI. Greenhouse heating. XVII. Vacuum vapor and
+    vacuum exhaust heating. XVIII. Miscellaneous heating. XIX.
+    Radiator and pipe connections. XX. Ventilation. XXI. Mechanical
+    ventilation and hot-blast heating. XXII. Steam appliances.
+    XXIII. District heating. XXIV. Pipe and boiler covering. XXV.
+    Temperature regulation and heat control. XXVI. Business methods.
+    XXVII. Miscellaneous. XXVIII. Rules, tables, and useful
+    information. 367 pages, 300 detailed engravings. 2nd
+    Edition--Revised. Price =$3.00=
+
+
+=Five Hundred Plain Answers to Direct Questions on Steam, Hot-Water,
+Vapor and Vacuum Heating Practice.= By ALFRED G. KING.
+
+    This work, just off the press, is arranged in question and
+    answer form; it is intended as a guide and text-book for the
+    younger, inexperienced fitter and as a reference book for all
+    fitters. This book tells "how" and also tells "why". No work of
+    its kind has ever been published. It answers all the questions
+    regarding each method or system that would be asked by the steam
+    fitter or heating contractor, and may be used as a text or
+    reference book, and for examination questions by Trade Schools
+    or Steam Fitters' Associations. Rules, data, tables and
+    descriptive methods are given, together with much other detailed
+    information of daily practical use to those engaged in or
+    interested in the various methods of heating. Valuable to those
+    preparing for examinations. Answers every question asked
+    relating to modern Steam, Hot-Water, Vapor and Vacuum Heating.
+    Among the contents are: The Theory and Laws of Heat. Methods of
+    Heating. Chimneys and Flues. Boilers for Heating. Boiler
+    Trimmings and Settings. Radiation. Steam Heating. Boiler,
+    Radiator and Pipe Connections for Steam Heating. Hot Water
+    Heating. The Two-Pipe Gravity System of Hot Water Heating. The
+    Circuit System of Hot Water Heating. The Overhead System of Hot
+    Water Heating. Boiler, Radiator and Pipe Connections for Gravity
+    Systems of Hot Water Heating. Accelerated Hot Water Heating.
+    Expansion Tank Connections. Domestic Hot Water Heating. Valves
+    and Air Valves. Vacuum Vapor and Vacuo-Vapor Heating. Mechanical
+    Systems of Vacuum Heating. Non-Mechanical Vacuum Systems. Vapor
+    Systems. Atmospheric and Modulating Systems. Heating
+    Greenhouses. Information, Rules and Tables. 200 pages, 127
+    illustrations. Octavo. Cloth. Price =$1.50=
+
+
+~STEEL~
+
+
+=Steel: Its Selection, Annealing, Hardening, and Tempering.= By E. R.
+MARKHAM.
+
+    This work was formerly known as "The American Steel Worker," but
+    on the publication of the new, revised edition, the publishers
+    deemed it advisable to change its title to a more suitable one.
+    It is the standard work on Hardening, Tempering, and Annealing
+    Steel of all kinds. This book tells how to select, and how to
+    work, temper, harden, and anneal steel for everything on earth.
+    It doesn't tell how to temper one class of tools and then leave
+    the treatment of another kind of tool to your imagination and
+    judgment, but it gives careful instructions for every detail of
+    every tool, whether it be a tap, a reamer or just a
+    screw-driver. It tells about the tempering of small watch
+    springs, the hardening of cutlery, and the annealing of dies. In
+    fact, there isn't a thing that a steel worker would want to know
+    that isn't included. It is the standard book on selecting,
+    hardening and tempering all grades of steel. Among the chapter
+    headings might be mentioned the following subjects:
+    Introduction; the workman; steel; methods of heating; heating
+    tool steel; forging; annealing; hardening baths; baths for
+    hardening; hardening steel; drawing the temper after hardening;
+    examples of hardening; pack hardening; case hardening; spring
+    tempering; making tools of machine steel; special steels; steel
+    for various tools; causes of trouble; high-speed steels, etc.
+    400 pages. Very fully illustrated. Fourth edition. Price =$2.50=
+
+
+=Hardening, Tempering, Annealing, and Forging of Steel.= By J. V.
+WOODWORTH.
+
+    A new work treating in a clear, concise manner all modern
+    processes for the heating, annealing, forging, welding,
+    hardening and tempering of steel, making it a book of great
+    practical value to the metal-working mechanic in general, with
+    special directions for the successful hardening and tempering of
+    all steel tools used in the arts, including milling cutters,
+    taps, thread dies, reamers, both solid and shell, hollow mills,
+    punches and dies, and all kinds of sheet-metal working tools,
+    shear blades, saws, fine cutlery, and metal-cutting tools of all
+    description, as well as for all implements of steel both large
+    and small. In this work the simplest and most satisfactory
+    hardening and tempering processes are given.
+
+    The uses to which the leading brands of steel may be adapted are
+    concisely presented, and their treatment for working under
+    different conditions explained, also the special methods for the
+    hardening and tempering of special brands.
+
+    A chapter devoted to the different processes for case-hardening
+    is also included, and special reference made to the adaptation
+    of machinery steel for tools of various kinds, Fourth edition.
+    288 pages. 201 illustrations. Price =$2.50=
+
+
+~TRACTORS~
+
+
+=The Modern Gas Tractor.= By VICTOR W. PAGE, M.E.
+
+    A complete treatise describing all types and sizes of gasoline,
+    kerosene and oil tractors. Considers design and construction
+    exhaustively, gives complete instructions for care, operation
+    and repair, outlines all practical applications on the road and
+    in the field. The best and latest work on farm tractors and
+    tractor power plants. A work needed by farmers, students,
+    blacksmiths, mechanics, salesmen, implement dealers, designers,
+    and engineers. Second edition, revised and enlarged. 504 pages.
+    Nearly 300 illustrations and folding plates. Price =$2.00=
+
+
+~TURBINES~
+
+
+=Marine Steam Turbines.= By DR. G. BAUER and O. LASCHE. Assisted by E.
+LUDWIG and H. VOGEL.
+
+    Translated from the German and edited by M. G. S. Swallow. The
+    book is essentially practical and discusses turbines in which
+    the full expansion of steam passes through a number of separate
+    turbines arranged for driving two or more shafts, as in the
+    Parsons system, and turbines in which the complete expansion of
+    steam from inlet to exhaust pressure occurs in a turbine on one
+    shaft, as in the case of the Curtis machines. It will enable a
+    designer to carry out all the ordinary calculation necessary for
+    the construction of steam turbines, hence it fills a want which
+    is hardly met by larger and more theoretical works. Numerous
+    tables, curves and diagrams will be found, which explain with
+    remarkable lucidity the reason why turbine blades are designed
+    as they are, the course which steam takes through turbines of
+    various types, the thermodynamics of steam turbine calculation,
+    the influence of vacuum on steam consumption of steam turbines,
+    etc. In a word, the very information which a designer and
+    builder of steam turbines most requires. Large octavo, 214
+    pages. Fully illustrated and containing eighteen tables,
+    including an entropy chart. Price, net =$3.50=
+
+
+~WATCH MAKING~
+
+
+=Watchmaker's Handbook.= By CLAUDIUS SAUNIER.
+
+    No work issued can compare with this book for clearness and
+    completeness. It contains 498 pages and is intended as a
+    workshop companion for those engaged in watch-making and allied
+    mechanical arts. Nearly 250 engravings and fourteen plates are
+    included. This is the standard work on watch-making. Price
+    =$3.00=
+
+
+~WELDING~
+
+
+=Automobile Welding with the Oxy-Acetylene Flame.= By M. KEITH DUNHAM.
+
+    Explains in a simple manner apparatus to be used, its care, and
+    how to construct necessary shop equipment. Proceeds then to the
+    actual welding of all automobile parts, in a manner
+    understandable by every one. _Gives principles never to be
+    forgotten._ Aluminum, cast iron, steel, copper, brass, bronze,
+    and malleable iron are fully treated, as well as a clear
+    explanation of the proper manner to burn the carbon out of the
+    combustion head. This book is of utmost value, since the
+    perplexing problems arising when metal is heated to a melting
+    point are fully explained and the proper methods to overcome
+    them shown. 167 pages, fully illustrated. Price =$1.00=
+
+
+
+
+    Every Practical Man Needs A Magazine Which Will Tell Him How To
+    Make And Do Things
+
+
+    _=Have us enter your subscription to the best mechanical magazine
+    on the market. Only one dollar a year for twelve numbers.
+    Subscribe today to=_
+
+    =Everyday Engineering=
+
+A monthly magazine devoted to practical mechanics for everyday men. Its
+aim is to popularize engineering as a science, teaching the elements of
+applied mechanics and electricity in a straightforward and
+understandable manner. The magazine maintains its own experimental
+laboratory where the devices described in articles submitted to the
+Editor are first tried out and tested before they are published. This
+important innovation places the standard of the published material very
+high, and it insures accuracy and dependability.
+
+The magazine is the only one in this country that specializes in
+practical model building. Articles in past issues have given
+comprehensive designs for many model boats, including submarines and
+chasers, model steam and gasoline engines, electric motors and
+generators, etc., etc. This feature is a permanent one in this magazine.
+
+Another popular department is that devoted to automobiles and airplanes.
+Care, maintenance, and operation receive full and authoritative
+treatment. Every article is written from the practical, everyday man,
+standpoint rather than from that of the professional.
+
+The magazine entertains while it instructs. It is a journal of
+practical, dependable information given in such a style that it may be
+readily assimilated and applied by the man with little or no technical
+training. The aim is to place before the man who leans toward practical
+mechanics, a series of concise, crisp, readable talks on what is going
+on and _how it is done_. These articles are profusely illustrated with
+clear, snappy photographs, specially posed to illustrate the subject in
+the magazine's own studio by its own staff of technically-trained
+illustrators and editors.
+
+=The subscription price of the magazine is one dollar per year of twelve
+numbers. Sample copy sent on receipt of ten cents.=
+
+Enter your subscription to this practical magazine with your bookseller.
+
+
+=The Norman W. Henley Publishing Co.,=
+
+=2 West 45th Street, New York=
+
+
+
+
+  +-----------------------------------------------------------------+
+  |                      TRANSCRIBER'S NOTES                        |
+  |                                                                 |
+  | General remarks:                                                |
+  |   There are some differences in wording between the Table of    |
+  |   Contents, the lists of sections per chapter, and the actual   |
+  |   section titles. Their meaning is clear, and they have been    |
+  |   left as they were in the original work.                       |
+  |   Page 56, table: Fig. 8 in the first column does not refer to  |
+  |   Fig. 8 in this work.                                          |
+  |   The original work does not have a Figure 89.                  |
+  |   Page 303, table: it is uncertain what "free with kerosene"    |
+  |   means, there may be a word omitted.                           |
+  |   Page 544, entirely censored. It is not clear what this page   |
+  |   originally contained (possibly a table), since text and       |
+  |   numbering of illustrations are uninterrupted. The text        |
+  |   "CENSORED" has been moved to after the first paragraph of the |
+  |   section on Mercedes Engines.                                  |
+  |   The List of Illustrations does not occur in the original work.|
+  |                                                                 |
+  | Changes made:                                                   |
+  |   The text of the original work (including inconsistencies in   |
+  |   accents, spelling, hyphenation and lay-out, and differences   |
+  |   between the main text, illustrations and advertisements) has  |
+  |   been followed, except when listed below. Only some minor      |
+  |   obvious typographical errors have been corrected silently.    |
+  |   Where the author used x for multiplication, this has been     |
+  |   replaced by x in the body of the text (not in the             |
+  |   advertisements or illustrations).                             |
+  |   The illustrations have been moved so as not to disrupt the    |
+  |   flow of the text.                                             |
+  |   Engine and aircraft types are not always named consistently in|
+  |   the original; Curtiss engine O X 2, OX-2 and 0X2 have all     |
+  |   been changed to OX-2, Curtiss aircraft JN4 and JN-4 to JN-4.  |
+  |   Multi-page tables: repeated headings have been removed, and   |
+  |   the tables treated as one consecutive table.                  |
+  |   Page 22: "The product of" has been moved into the first       |
+  |   formula.                                                      |
+  |   Page 25: "When B x r = M" changed to "When P x r = M".        |
+  |   Page 74: ".225 / 775 = .2905" changed to ".225 / .775 =       |
+  |   .2905".                                                       |
+  |   Page 137 (caption): "Bavary" changed to "Baverey" as          |
+  |   elsewhere.                                                    |
+  |   Page 172: "evidently" changed to "evident".                   |
+  |   Page 214: "drop to O" changed to "drop to 0".                 |
+  |   Page 248: "actual from a common" changed to "actuated from a  |
+  |   common".                                                      |
+  |   Page 256: "values" changed to "valves".                       |
+  |   Page 280: "Fig. 6" changed to "Fig. 112".                     |
+  |   Page 306: "Fig. 127, B" changed to "Fig. 127, C" (2nd         |
+  |   reference).                                                   |
+  |   Page 324: "Rhone" changed to "Le Rhone" as elsewhere.         |
+  |   Page 334: "Check values" changed to "Check valves".           |
+  |   Page 364: "LeRhone" changed to "Le Rhone" as elsewhere.       |
+  |   Page 390: "Fig. 62, D" changed to "Fig. 168, B".              |
+  |   Page 408: "Stilson" changed to "Stillson" as elsewhere.       |
+  |   Page 490: "both valves" changed to "both halves".             |
+  |   Page 514: "standard ratio is 5.3" changed to "standard ratio  |
+  |   is 5:3".                                                      |
+  |   Page 529: "gallons per minute 1,400 R. P. M." changed to      |
+  |   "gallons per minute at 1,400 R. P. M."                        |
+  |   Page 546: "Hispano Suiza" changed to "Hispano-Suiza" as       |
+  |   elsewhere.                                                    |
+  |   Page 556: "Diameter of crank-shaft, 56 mm." changed to        |
+  |   "Diameter of crank-shaft, 55 mm."                             |
+  |   Page 7 (advertisements): "Hazlehurst Field" changed to        |
+  |   "Hazelhurst Field".                                           |
+  |   Page 21 (advertisements): "Rhose Island Compound" changed to  |
+  |   "Rhode Island Compound".                                      |
+  |   Index: "Shebler" changed to "Schebler", "camshaft" to         |
+  |   "cam-shaft", "wristpin" to "wrist-pin", etc. (all as in text).|
+  +-----------------------------------------------------------------+
+
+
+
+***END OF THE PROJECT GUTENBERG EBOOK AVIATION ENGINES***
+
+
+******* This file should be named 38187.txt or 38187.zip *******
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