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diff --git a/42369-8.txt b/42369-8.txt deleted file mode 100644 index 5047fbb..0000000 --- a/42369-8.txt +++ /dev/null @@ -1,6643 +0,0 @@ -The Project Gutenberg EBook of Motors, by James Slough Zerbe - -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: Motors - -Author: James Slough Zerbe - -Release Date: March 19, 2013 [EBook #42369] - -Language: English - -Character set encoding: ISO-8859-1 - -*** START OF THIS PROJECT GUTENBERG EBOOK MOTORS *** - - - - -Produced by Greg Bergquist, Tom Cosmas and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from images generously made available -by The Internet Archive/American Libraries.) - - - - - - - - - -Transcriber's Note - -Italic text is denoted by _underscores_ and bold text by =equal signs=. - -Whole numbers with fractional parts are denoted as 7-3/4. - - - - - _Every Boy's - Mechanical - Library_ - -[Illustration] - - -MOTORS - - - - -Every Boy's Mechanical Library - - -By J. S. ZERBE, M.E. - -Price, per volume, 60 cents, Net. Postage extra. - - -AUTOMOBILES - -This is a subject in which every boy is interested. While few mechanics -have the opportunity to actually build an automobile, it is the -knowledge which he must acquire about every particular device used, that -enables him to repair and put such machines in order. The aim of this -book is to make the boy acquainted with each element, so that he may -understand why it is made in that special way, and what the advantages -and disadvantages are of the different types. To that end each structure -is shown in detail as much as possible, and the parts separated so as to -give a clear insight of the different functions, all of which are -explained by original drawings specially prepared to aid the reader. - - -MOTORS - -To the boy who wants to know the theory and the practical working of the -different kinds of motors, told in language which he can understand, and -illustrated with clear and explicit drawings, this volume will be -appreciated. It sets forth the groundwork on which power is based, and -includes steam generators, and engines, as well as wind and water -motors, and thoroughly describes the Internal Combustion Engine. It has -special chapters on Carbureters, Ignition, and Electrical systems used, -and particularly points out the parts and fittings required with all -devices needed in enginery. It explains the value of compounding, -condensing, pre-heating and expansion, together with the methods used to -calculate and transmit power. Numerous original illustrations. - - -AEROPLANES - -This work is not intended to set forth the exploits of aviators nor to -give a history of the Art. It is a book of instructions intended to -point out the theories of flying, as given by the pioneers, the -practical application of power to the various flying structures; how -they are built; the different methods of controlling them; the -advantages and disadvantages of the types now in use; and suggestions as -to the directions in which improvements are required. It distinctly -points out wherein mechanical flight differs from bird flight, and what -are the relations of shape, form, size and weight. It treats of kites, -gliders and model aeroplanes, and has an interesting chapter on the -aeroplane and its uses in the great war. All the illustrations have been -specially prepared for the work. - - CUPPLES & LEON CO., Publishers, NEW YORK - - - - -[Illustration] - - - -_Every Boy's Mechanical Library_ - - -MOTORS - - -BY -J. S. ZERBE, M.E. - -_Author of Aeroplanes--Automobiles_ - - -_ILLUSTRATED_ - - -NEW YORK -CUPPLES & LEON COMPANY - - - - -Copyright, 1915, by -CUPPLES & LEON COMPANY - - - - -CONTENTS - - - PAGE - - Introductory 1 - - The Subject. The Inquisitive Trait. The Reasons for Doing - Things. The Mystery of Mechanism. Curiosity which prompts - Investigation. The Sum of Knowledge. - - Chapter I. Motors and Motive Power 5-21 - - The Water Fall. Water moves in One Direction only. What is - Energy. Stored or Potential Energy. Kinetic Energy. - Friction. Resistance. Inertia. The Law of Bodies. Internal - and External Resistance. Momentum. Energy Indestructible. - Wind Power. Rectilinear Motion. Oscillating Motion. - Movements in Nature. How Man Utilizes the Various Movements. - Kinds of Potential Energy. The Power in Heat. Energy in - Steam. Energy from the Sun. Power from Water. The Turbine. - Calculating Power of a Turbine. Horse Power. Foot Pounds. - Power and Time. Gravitation. Utilizing the pull of Gravity. - Taking Advantages of Forces. Pitting Forces Against each - Other. Centripetal and Centrifugal Forces. Power not Created. - Developing the Power of Motors. Experimenting. - - Chapter II. The Steam Generator 22-31 - - Water as an absorbent of Heat. Classification of Boilers. - Mode of applying Heat. The Cylindrical Boiler. The Cornish - Boiler. The Water Tube Boiler. Various Boiler Types. Compound - Steam Boiler. Locomotive Steam Boiler. Vertical Steam Boiler. - - Chapter III. Steam Engines 32-59 - - The Original Turbine Engine. The Reciprocating Engine. - Atmospheric Engine. The Piston. Importance of the Valve. - Expanding the Steam. Balanced Valve. Rotary Valve. Engine - Accessories. Efficiency of Engines. How Steam acts in a - Cylinder. Indicating the Engine. Mean Efficiency. - Calculating Horse Power. Condensation. Atmospheric Pressure. - The Condenser. Pre-heating. Superheaters. Compounding. Triple - and Quadruple Expansion Engines. The Steam Turbine. Pressure - and Velocity. Form of Blades. Compounding the Jet. - - Chapter IV. Fuels and Combustion 60-67 - - Solid Fuels. Liquid Fuels. Combustion. Oxidation. The - Hydro-Carbon Gases. Oxygen and the Atmosphere. Internal - Combustion. Vaporizing Fuel. Explosion by Heat Compression. - How Compression Heats. Elasticity of Gases. Advantages of - Compression. The Necessity of Compression. - - Chapter V. The Internal Combustion Engine 68-82 - - Fixed Gases. Gas Engines. Energy of Carbon and Hydrogen. - The Two-Cycle Type. Advantages of the Two-Cycle Engine. The - Four-Cycle Engine. The Four Cycles. Ignition Point. Advantages - of the Four-Cycle Type. The Loss in Power. Engine - Construction. Valve Grinding. The Crank Shaft. The Cams. - - Chapter VI. Carbureters 83-101 - - Functions of a Carbureter. Rich Mixtures. Lean Mixtures. - Types of Carbureters. The Sprayer. The Surface Type. - Governing a Carbureter. Primary Air. Needle Valve. Secondary - Air. Requirements in a Carbureter. Size of a Carbureter. Rule - for Size of Carbureters. The Throttle. Flooding. - Adjustability. Surface Carbureters. Float Chamber. - - Chapter VII. Ignition, Low Tension System 102-120 - - Electricity. Magnetism. The Armature. Characteristics of - Electricity. Make and Break System. Voltage. High and Low - Voltage. Low Tension method. Disadvantages of Make and Break. - Amperes. Resistance. Direct Current. Alternating Current. - Induction. Generating Electricity. Primary Battery. Making a - Dry Cell. Energy in a cell. Wiring Methods. Series Connection. - Multiple Connection. Series Multiple. Watts. Testing a Cell. - Testing with Instruments. Simple Battery Make and Brake - System. To Advance the Spark. The Magneto in the Circuit. - Magneto Spark Plug. - - Chapter VIII. Ignition, High Tension 121-140 - - Magnetos. Alternating Current. Cutting Lines of Force. - Plurality of Loops. The Electro Magnet. The Dynamo Form. The - Magneto Form. Advantages of the Magneto. Induction Coil. - Changing the Current. Construction of a Coil. Primary Coil. - Secondary Coil. Contact Maker. High Tension with Battery and - Coil. Metallic Core for Induction Coil. The Condenser. - Operations of a Vibrator Coil. The Distributor. Circuiting - with Distributor. - - Chapter IX. Mechanical Devices Utilized in Power 141-157 - - The Unit of Time. Horse Power. Proney Brake. Reversing - Mechanism. Double Eccentric Reversing Gear. Balanced Slide - Valve. Balanced Throttle Valve. Engine Governors. Injectors. - Feed Water Heaters. - - Chapter X. Valves and Valve Fittings 158-171 - - Check Valve. Gate Valve. Globe Valve. The Corliss Valve. - Corliss Valve-operating Mechanism. Angle Valve. Rotary Valves. - Rotable Engine Valves. Throttle Valves. Blow-off Valves. - Pop-Safety Valves. - - Chapter XI. Cams and Eccentrics 172-178 - - Simple Cams. Wiper Wheels. Cylindrical Cam Motion. Eccentrics. - Triangularly-formed Eccentrics. - - Chapter XII. Gears and Gearing 179-190 - - Racks and Pinions. Mangle Rack. Controlling the Pinion. Dead - Center. Crank Motion Substitute. Mangle Wheels. Quick Return - Motion. Accelerated Motion. Quick-return Gearing. Scroll - Gearing. - - Chapter XIII. Special Types of Engines 191-201 - - Temperatures. Artificial Heat. Zero. Liquids and Gases. - Refrigeration. Rotary Engines. Caloric Engines. Adhesion - Engines. - - Chapter XIV. Enginery in the Development of the Human Race 202-207 - - Power in Transportation. Power vs. Education and the Arts. - Lack of Power in the Ancient World. The Early Days of the - Republic. Lack of Cohesiveness in Countries Without Power. - The Railroad as a Factor in Civilization. The Wonderful - Effects of Power. England as a User of Power. The Automobile. - High Character of Motor Study. The Unlimited Field of Power. - - Chapter XV. The Energy of the Sun, and How Heat is Measured 208-216 - - Fuel Economy. Direct Conversion. The Measurement of Heat. - Caloric. Material Theory. Heat Transmitted in Three Ways. - Conduction. Convection. Radiation. - - Glossary 217 - - -LIST OF ILLUSTRATIONS - - - FIG. PAGE - - 1. Undershot Wheel 13 - 2. Overshot Wheel 14 - 3. Primitive Boiler 24 - 4. Return Tubular Boiler 25 - 5. Cornish, or Scotch Boiler 25 - 6. Water Tube Boiler. End view 27 - 7. Water Tube Boiler. Side view 29 - 8. The Original Engine 33 - 9. Horizontal Section of Tube 33 - 10. Steam-Atmospheric Engine 35 - 11. Simple Valve Motion. First position 38 - 12. Simple Valve Motion. Second position 38 - 13. Effective pressure in a Cylinder 42 - 14. Indicating pressure line 44 - 15. Indicating the Engine 45 - 16. Compound Engine 53 - 16a. Relative Piston Pressures 54 - 17. Changing Pressure into Velocity 55 - 18. Reaction against Air 56 - 19. Reaction against Surface 56 - 20. Turbine. Straight Blades 57 - 21. Curved Blades 58 - 22. Compound Turbine 58 - 23. Two-Cycle Engine. First position 71 - 24. Two-Cycle Engine. Second position 73 - 25. Two-Cycle Engine. Third position 73 - 26. Four-Cycle Engine. First position 75 - 27. Four-Cycle Engine. Second position 75 - 28. Four-Cycle Engine. Third position 76 - 29. Four-Cycle Engine. Fourth position 76 - 30. Valve Grinding 81 - 31. Carbureter 87 - 32. Carbureter 95 - 33. Surface Carbureter 98 - 34. Dry Cell 108 - 35. Series Connection 109 - 36. Multiple, or Parallel Connection 110 - 37. Series-Multiple Connection 111 - 38. Circuit Testing 113 - 39. Make and Break, with Battery 114 - 40. Make and Break, with Magneto 117 - 41. Magneto Spark Plug 119 - 42. Illustrating Alternating Current 122 - 43. Alternating Current. Second position 122 - 44. Alternating Current. Third position 123 - 45. Alternating Current. Fourth position 124 - 46. Making the Circuit 125 - 47. The Dynamo 126 - 48. The Magneto 126 - 49. Current by Induction 128 - 50. Induction Coil 129 - 51. Typical Induction Coil 130 - 52. Contact Maker 131 - 53. Typical Circuiting, Jump spark Ignition 132 - 54. Metallic Core, Induction Coil 133 - 55. Condenser 134 - 56. Vibrator Coil and Connections 135 - 57. The Distributer 137 - 58. Circuiting with Distributer 138 - 59. Illustrating the Unit of Time 142 - 60. The Proney Brake 143 - 61. Double Eccentric Reversing Gear 146 - 62. Reversing Gear, Neutral 146 - 63. Reversing Gear, Reversed 147 - 64. Single Eccentric Reversing Gear 147 - 65. Balanced Slide Valve 148 - 66. Valve Chest. Double Port Exhaust 149 - 67. Balanced Throttle-Valve 150 - 68. Watt's Governor 151 - 69. The Original Injector 152 - 70. Injector with movable Combining Tube 154 - 71. Feed Water Heater 156 - 72. Check Valve 158 - 73. Gate Valve 159 - 74. Globe Valve 160 - 75. Corliss Valve 162 - 76. Corliss Valve-operating Mechanism 163 - 77. Angle Valve 164 - 78. Rotary-Valve 165 - 79. Two-way Rotary 165 - 80. Rotary Type 166 - 81. Two-Way Rotary Type 166 - 82. Butterfly Throttle 167 - 83. Angle Throttle 167 - 84. Slide Throttle 168 - 85. Two-slide Throttle 168 - 86. Blow-off Valve 169 - 87. Safety Pop Valve 170 - 88. Heart Shaped 173 - 89. Elliptic 173 - 90. Double Elliptic 173 - 91. Single Wiper 174 - 92. Double Wiper 174 - 93. Tilting Cam 174 - 94. Cam Sector 175 - 95. Grooved Cam 175 - 96. Reciprocating Motion 175 - 97. Pivoted Follower for Cam 176 - 98. Eccentric 177 - 99. Eccentric Cam 177 - 100. Triangularly-formed Eccentric 178 - 101. Rack and Pinion 180 - 102. Rack Motion 180 - 103. Plain Mangle Rack 181 - 104. Mangle Rack Motion 181 - 105. Alternate Circular Motion 181 - 106. Controlling Pinion for Mangle Rack 182 - 107. Illustrating Crank-pin Movement 183 - 108. The Dead Center 184 - 109. Crank Motion Substitute 184 - 110. Mangle Wheel 185 - 111. Quick Return Motion 186 - 112. Accelerated Circular Motion 187 - 113. Quick Return Gearing 188 - 114. Scroll Gearing 189 - 115. Simple Rotary Engine 196 - 116. Double-feed Rotary Engine 198 - 117. Adhesion Motor 200 - - - - -INTRODUCTORY - - -The motor is the great dominating factor in the world of industry. Every -wheel and spindle; every shaft and loom, and every piece of mechanism -which has motion, derives it from some sort of motor. - -The term _motor_ has a wider significance than any other word. A steam -engine is a motor, and so, also, is a dynamo, a water wheel or a wind -mill. - -It would be just as descriptive to call a wind mill a wind _motor_, or a -steam engine a steam _motor_, as to adhere to the old terms; and, on the -other hand, since it would be out of place to call a dynamo or a wind -mill an engine, the word _motor_ seems best adapted to express the -meaning of every type of mechanism which transforms energy into motion. - -In considering the subject I shall proceed on the theory that the boy -knows nothing whatsoever of the subject, nor the terms used to designate -the various phases, subjects and elements. It must be elementary in its -character, and wholly devoid of technical terms or sentences. - -While it is necessary to give information in a book of this character, -on the methods for figuring out power, it must be done without resorting -to the formulas usually employed in engineering works, as they are of -such a nature that the boy must have some knowledge of the higher -mathematics to follow out the calculations employed. - -Indeed, every phase should be brought within the mental view of the boy, -and to do this may occasionally necessitate what might appear to be long -drawn out explanations, all of which, it is hoped, will be the means of -more clearly presenting the subject. - -The opening chapters, which treat of the fundamentals, will be as nearly -complete as possible, and thus lay a foundation for the work we shall be -called upon to perform, when we treat of the structures of the different -parts and devices in the various types of motors. - -The object is to explain power in its various phases, how derived, and -the manner in which advantage is taken of the elements, and substances -with which we are brought into contact. The reasons for each step are -plainly set forth with the view of teaching the boy what power means, -rather than to instruct him how to make some particular part of the -machinery. - -_The Inquisitive Trait._--My experience has impressed me with the -universality of one trait in boys, namely, that of inquisitiveness. Put -a machine before a boy and allow him to dissect it, and his curiosity -will prompt him to question the motive for the particular construction -of each part of its make-up. - -_The Reasons for Doing Things._--He is interested in knowing the reason -why. Every boy has the spirit of the true investigator,--that quality -which seeks to go behind or delve down deeply. This is a natural -instinct. - -_The Mystery of Mechanism._--If this taste is gratified, and he thereby -learns the mystery of the machine, what a wonderful world is opened to -him! The value of the lesson will depend, in a large measure, on the -things which he has found out for himself. It is that which counts, -because he never forgets that which he has dug out and discovered. - -_Curiosity Which Prompts Investigation._--I recall a farmer's boy whose -curiosity led him to investigate the binding mechanism of a reaper. It -was a marvel to him, as it has been to many others. He studied it day -after day, and finally, unaided mastered the art. That was something -which could not be taken away from him. - -It was a pleasure to hear him explain its operation to a group of boys, -and men, too, in which he used the knot itself to explain how the -various fingers and levers coöperated to perform their functions. It was -an open book to him, but there was not one in the group of listeners who -could repeat the explanation. - -_The Sum of Knowledge._--It is the self-taught boy who becomes the -expert. The great inventors did not depend on explanations. A book of -this character has a field of usefulness if it merely sets forth, as far -as possible, the sum of useful knowledge which has been gained by -others, so as to enable the boy to go forward from that point, and thus -gain immensely in time. - -There is so much that has been developed in the past, with reference to -the properties of matter, or concerning the utility of movements, and -facts in the realm of weights, measures, and values of elements which he -must deal with, that, as he studies the mechanical problems, the book -becomes a sort of cyclopedia, more than a work designed to guide him in -the building of special engines or motors. - -The Author. - - - - -MOTORS - - - - -CHAPTER I - -MOTORS AND MOTIVE POWER - - -What makes the wheels turn round? This simple question is asked over and -over again. To reply means pages of answers and volumes of explanations. - -The Water Fall.--Go with me to the little stream I have in mind, and -stand on the crest of the hill where we can see the water pouring down -over the falls, and watch it whirling away over the rocks below. - -The world was very, very old, before man thought of using the water of -the falls, or the rushing stream below, to grind his corn or to render -him other service. - -Water Moves in One Direction Only.--What the original man saw was a body -of water moving in one direction only. When he wanted to grind corn he -put it in the hollow of a rock, and then beat it with a stone, which he -raised by hand at each stroke. In doing so two motions were required in -opposite directions, and it took thousands of years for him to learn -that the water rushing along in one direction, could be made to move the -stone, or the pestle of his primitive grinding mill, in two directions. - -It took him thousands of years more to learn another thing, namely, that -the water could be made to turn the stone round, or rotate it, and thus -cause one stone, when turning on another, to crush and grind the grain -between them. - -Now, as we go along with the unfolding of the great question of -_motors_, we must learn something of the terms which are employed, to -designate the different things we shall deal with, and we ought to have -some understanding of the sources of power. - -What Is Energy?--The running, as well as the falling water represent -energy. This is something which is in the thing, the element, or the -substance itself. It does not come from without. It is not imparted to -it by anything. - -Stored or Potential Energy.--At the top of the falls, look at that -immense rock. It has been there for centuries. It, also, has energy. -There is stored within it a tremendous power. You smile! Yes, the power -has been there for ages, and now by a slight push it is sent crashing -down the precipice. The power developed by that fall was thousands of -times greater than the push which dislodged it. - -But, you say, the push against the stone represented an external force, -and such being the case, why do you say that power is within the thing -itself? The answer is, that not one iota of the power required to push -the stone off its seat was added to the power of the stone when it fell. -Furthermore, the power required to dislodge the stone came from within -me, and not from any outside source. - -Here we have two different forms of energy, but both represent a moving -force. The power derived from them is the same. - -Kinetic Energy.--The energy of the falling water or stone is called -_Kinetic_ energy. In both cases the power developed came from within -themselves and not from any exterior source. - -The difference between Potential and Kinetic Energy is therefore that -Potential Energy represents the capacity to do work, while Kinetic -Energy is the actual performance of work. - -Friction.--In every form of energy there is always something to detract -from it or take away a portion of its full force, called _friction_. -When a shaft turns, it rubs against the bearings, and more or less power -is absorbed. - -When a wheel travels over the ground friction is ever present. The -dislodging of the stone required ten pounds of energy, but a thousand -pounds was developed by the fall. The water rushing along its rocky bed -has friction all along its path. - -Resistance.--This friction is a resistance to the movement of a body, -and is ever present. It is necessary to go back and examine the reason -for this. As long as the stone was poised at the top of the precipice it -had latent or potential energy, which might be termed _power at rest_. -When it fell it had power in motion. In both cases gravity acted upon -the stone, and in like manner on the water pouring over the falls. - -Inertia.--Inertia or momentum is inherent in all things and represents -the resistance of any body or matter, to change its condition of rest or -standing still into motion, and is then called _Inertia of Rest_, or the -resistance it offers to increase or decrease its speed when moving, and -is then called _Inertia of Motion_. - -Inertia or momentum is composed by the weight of the body and its speed -and is measured by multiplying its weight by its speed. - -The law is, that when a body is at rest it will remain at rest -eternally, and when in motion it will continue in motion forever, unless -acted on by some external force or resistance. An object lying on the -ground has the frictional resistance of the earth to prevent its moving. -When the object is flying through space it meets the air and has also -the downward pull of gravity, which seek to bring it to rest. - -These resisting forces are less in water, and still less in gases, and -there is, therefore, a state of mobility in them which is not found in -solids. - -Internal and External Resistance.--All bodies are subject to internal, -as well as external resistance. The stone on the cliff resisted the -movement to push it over. Weight was the resisting internal force, but -when the stone was moving through the air, the friction with the air -created external resistance. - -Energy Indestructible.--There is another thing which should be -understood, and that is the absolute indestructibility of energy. Matter -may be changed in form, or in the direction of its motion, by the change -of kinetic into potential energy, or vice versa, but the sum total of -the energy in the world is unalterable or constant. - -The tremendous power developed by the stone when it plunged through -space and struck the rocks below, developed a heat at its impact. Thus -the moving force which was a motion in one direction was converted into -another form of energy, heat. The expansion of the material exposed to -the heat also represented energy. - -When powder explodes and absolutely changes the form of the substance, -its volume of expansion, if it should be retained within a vessel, would -perform a certain amount of work, and the energy is thus transferred -from one form to another without ceasing. - -Wind Power.--Primitive man also saw and felt the winds. He noted its -tremendous power, but he could not see how a force moving in one -direction only could be utilized by him. - -Rectilinear Motion.--This movement of the wind in one direction, like -the water flowing along the bed of the river, is called _rectilinear_ -motion. It required invention to convert rectilinear into circular -motion. - -Oscillating Motion.--When he threshed his grain and winnowed it by -shaking it to and fro, to rid it of the chaff, the idea of using the -wind to produce an oscillating motion did not occur to him. After -circular motion was produced, the crank was formed and thus the -oscillating movement was brought about. - -Movements in Nature.--All movements in nature are simple ones, of which -the following are illustrations: - -1. _Rectilinear_, which, as stated, means in a straight line. - -2. _Circular_, like the motion of the earth on its axis, once every -twenty-four hours. - -3. _Oscillatory_, like a to and fro movement, the swaying branches of -trees, or the swinging of a pendulum. - -How Man Utilizes the Various Movements.--What man has done is to utilize -the great natural forces in nature in such a way as to produce these -movements at will, in either direction, with greater or less speed, at -regular or irregular intervals, and at such amplitudes as are required -to perform the necessary work. - -Kinds of Potential Energy.--Now, materials have within themselves -_potential_ energy of various kinds. Thus, powder, if ignited, will -burn, and in burning will expand, or explode, as we term it. This is -true also of oils and gases. The expansion pressure produced from such -substances depends on the speed at which they will burn, and in so -confining the burning substances that a great pressure is produced. - -The Power in Heat.--The pressure of all such substances against the -confining medium depends on heat. Any gas which has 523 degrees of heat -imparted to it will expand double its volume. If one cubic inch of -water is converted into steam the latter will occupy one cubic foot of -space under atmospheric pressure,--that is, it will expand over 1700 -times. - -Energy in Steam.--If the steam thus generated is now subjected to 523 -degrees of heat additional, it will occupy over 3400 cubic inches of -space. It will thus be seen why steam, gas, and gasoline engines are -called _heat engines_, or heat _motors_. - -Energy From the Sun.--Many attempts have been made to utilize the heat -of the sun, to turn machinery, but the difficulty has been to secure -sufficient heat, on the one hand, and on the other to properly cool down -the heated gases, so that the various liquid and solid fuels are -required to make the heat transformations. - -Power From Water.--In the use of water two forms are available, one -where the water is moving along or falling in a constant open stream; -and the other where the flowing water is confined and where its flow can -be regulated and controlled. The latter is more available for two -reasons: - -First: Economy in the use of water. - -Second: Ability to control the speed or movement of the motor. - -With running or falling streams a large surface is required, and the -wheels turn slowly. Two well-recognized forms of wheels have been -employed, one called the undershot, or breast wheel, shown in Fig. 1, -and the other the overshot, illustrated in Fig. 2. - -[Illustration: _Fig. 1. Undershot Wheel._] - -In both types it is difficult to so arrange them as to shut off the -power or water pressure when required, or to regulate the speed. - -The Turbine.--Wheels which depend on the controllable pressure of the -water are of the turbine type. The word is derived from the Latin word -_turbo_, meaning to whirl, like a top. This is a type of wheel mounted -on the lower end of a vertical or horizontal shaft, within, or at the -bottom, of a penstock. The perimeter of the wheel has blades, and the -whole is enclosed within a drum, so that water from the penstock will -rush through the tangentially-formed conduit into the drum, and strike -the blades of the wheel. - -[Illustration: _Fig. 2. Overshot Wheel._] - -A column of water one inch square and twenty-eight inches high weighs -one pound,--or, to express it in another way, the pressure at the -bottom of such a column is one pound, and it is a pound for each -additional 28 inches. - -If there should be a head or height of water column of seven feet, the -pressure on each square inch of water at the bottom of the penstock -would be three pounds to the square inch. Assuming the opening or duct -leading to the wheel blades should be 12 × 12 inches, and also the -blades be 12 × 12 inches, the area would be equal to 144 square inches, -and this multiplied by three pounds would equal 432 pounds pressure -against the blades. - -Calculating Power of a Turbine Wheel.--The power of such a wheel depends -principally on two things. First, the arrangement of the blades with -reference to the inflowing water; and, second, the discharge port, or -ability of the water to free itself from the wheel casing. - -Let us assume that the diameter of the wheel at the center of the blades -is two feet, which would, roughly estimating, give a circumference of -six feet, or a travel of each particular blade that distance at each -turn of the wheel. - -If the wheel turns one hundred times a minute, and this is multiplied by -the circumference of the wheel (six feet), the result is 600 feet. This, -again, multiplied by 432 pounds (which represents the pressure of the -water on the entire discharge opening), and we have a product of -259,200, which represents _foot pounds_. - -This means the same work as if 259,200 pounds would have been lifted -through a space of one foot in one minute of time. To ascertain how much -power has been developed we must know how many foot pounds there are in -a horse power. - -Horse Power.--It is determined in this way: any force which is capable -of raising 550 pounds one foot in one second of time, is developing one -horse power. A man might have sufficient strength to raise such a weight -once, twice, or a dozen times in succession, but if he should try to do -it sixty times a minute he would find it a trying, if not impossible -task. - -Foot Pounds.--If he should be able to lift 550 pounds sixty times within -a minute, he would have lifted 33,000 pounds one foot in one minute of -time (550 × 60), and thus have developed one horse power. - -As the water wheel, in our calculations above, raised 259,200 pounds in -that period of time, this figure divided by 33,000 shows that a little -more than 7-3/4 horse power was developed, assuming, of course, that we -have not taken into account any waste, or loss by friction, or -otherwise. - -This method of determining one horse power should be carefully studied. -Always keep in mind the main factor, 33,000 pounds, and this multiplied -by one foot, the result will be 33,000 _foot pounds_,--that is, one -horse power. - -It would be just the same, however, if it were possible to raise one -pound 550 times in one second, or one pound 33,000 times within a -minute. - -Power and Time.--You are thus brought face to face with another thing -which is just as important, namely, that, in considering power, time, as -well as energy, must be considered. If a man, by superior strength, -could be able to raise 550 pounds once within a second, then skip a few -seconds, take another hold, and again raise it that distance, he would -not be developing one horse power for a minute, but only for one second -while he lifted the weight. For the whole minute he would only develop a -certain number of foot pounds, and less than 33,000 foot pounds. - -If, within a minute, he succeeded in raising it one foot for six times, -this would be six times 550, equal to 3,300 foot pounds, or just -one-tenth of one horse power for one minute; so _time_ is just as -important as the amount lifted at each effort. - -Gravitation.--Now, let us examine power from another standpoint. Every -attempt which man makes to produce motion is an effort to overcome some -resistance. In many cases this is "weight or gravity." While humanity -unceasingly antagonizes the force of gravity it is constantly utilizing -the laws of gravitation. - -Utilizing the Pull of Gravity.--The boy laboriously drags his sled to -the top of the hill against gravity, and then depends on that force to -carry him down. We have learned to set up one force in nature against -the other. The running stream; the moving winds; the tides; the -expansive force of all materials under heat, are brought into play to -counteract the great prevailing agency which seeks to hold everything -down to mother earth. - -Utilizing Forces.--The Bible says: Blessed is he who maketh two blades -of grass grow where one grew before. To do that means the utilization of -forces. Improved machinery is enabling man to make many blades grow -where one grew before. New methods to force the plow through the soil; -to dig it deeper; to fertilize it; and to harvest it; all require power. - -Pitting Forces Against Each Other.--Man has discovered how to pit the -forces of nature against each other, and the laws which regulate them. - -Centripetal and Centrifugal Forces.--Gravity, that action which seeks to -draw all matter toward the center of the earth, is termed _centripetal_ -force. But as the earth rotates on its axis another force is exerted -which tends to throw substances outwardly, like dirt flying from the rim -of a wheel. This is called _centrifugal_ force. - -Man utilizes this force in many ways, one of which is illustrated in the -engine governor, where the revolving balls raise the arms on which they -swing, and by that means the engine valve is regulated. - -Power Not Created.--In taking up the study of this subject start with a -correct understanding of the source of all power. It is inherent in all -things. All we can do is to liberate it, or to put the various materials -in such condition, that they will exert their forces for our uses. (See -Page nine, "Energy Indestructible.") - -A ton of coal, when burned, produces a certain amount of heat, which, if -allowed to escape, will not turn a wheel. But if confined, it expands -the air, or it may convert water into steam which will turn ponderous -machinery. Niagara Falls has sent its great volume into the chasm for -untold centuries, but it has never been utilized until within the last -twenty years. The energy has been there, nevertheless; and so it is with -every substance of which we have knowledge. - -The successive steps, wherein the experimenter and the inventor have -greatly improved on the original inventions, will be detailed as we go -along through the different types of motors. - -Developing the Power of Motors.--This development in the art is a most -fascinating study. It is like the explorer, forcing his way through a -primeval forest. He knows not what is beyond. Often, like the traveler, -he has met serious obstructions, and has had to deviate from his course, -only to learn that he took the wrong direction and had to retrace his -steps. - -The study of motors and motive power is one which calls for the highest -engineering qualities. In this, as in every other of the mechanical -arts, theory, while it has an important function, occupies second place. - -Experimenting.--The great improvements have been made by building and -testing; the advance has been step by step. Sometimes a most important -invention will loom up as a striking example to show how a valuable -feature lies hidden and undeveloped. - -An illustration of this may be cited with respect to the valve of the -steam engine. For four hundred years there was no striking improvement -in the valve. The various types of sliding and rocking valves were -modified and refined until it was assumed that they typified perfection. -At one stroke the Corliss valve made such an immense improvement that -the marvel was as much in its simplicity as in its performance. - -The reasons and the explanations will be set forth in the section which -analyzes valve motion. In this, as in other matters, it shall be our aim -to explain why the different improvements were regarded as epochs in the -production of motors. - - - - -CHAPTER II - -THE STEAM GENERATOR - - -The most widely known and utilized source of power is the steam engine. -Before its discovery wind and water were the only available means, -except the muscular power of man, horses and other animals, which was -used with the crudest sort of contrivances. - -In primitive days men did not value their time, so they laboriously -performed the work which machinery now does for us. - -The steam engine, like everything else which man has devised, was a -growth, and, singular as it may seem, the boiler, that vital part of the -organism, was, really, the last to receive due consideration and -improvement. - -As the boiler is depended upon to produce the steam pressure, and since -the pressure depends on the rapid and economical evaporation of water, -the importance of the subject will be understood in treating of the -steam engine. - -Water as an Absorbent of Heat.--Water has the capacity to absorb a -greater amount of heat than any other substance. A pewter pot, which -melts at 500 degrees, will resist 2000 degrees of heat if it is filled -with water, since the latter absorbs the heat so rapidly that the -temperature of the metal is kept near the boiling point of water, which -is 212 degrees. - -Notwithstanding the great heat-absorbing qualities of water, a large -portion of the heat of the fuel passes through the flues and escapes -from the stack. This fact has caused inventors to devise various forms -of boilers, the object being to present as large an area of water as -possible to the heat of the burning fuel. How that was accomplished we -shall try to make plain. - -Classification of Boilers.--Numerous types of boilers have been devised, -the object being, in all cases to evaporate the largest amount of water -with the minimum quantity of fuel. All boilers may be put under two -general heads, namely, those which contain a large quantity of water, -and those which are intended to carry only a small charge. - -In the first division the boilers are designed to carry a comparatively -small pressure, and in the latter high pressures are available. - -Mode of Applying Heat.--The most important thing to fully understand is -the manner in which heat is applied to the boiler, and the different -types which have been adapted to meet this requirement. - -The Cylindrical Boiler.--The most primitive type of boiler is a plain -cylindrical shell A, shown in Fig. 3, in which the furnace B is placed -below, so that the surface of the water in contact with the fire area is -exceedingly limited. - -[Illustration: _Fig. 3. Primitive Boiler._] - -In such a type of boiler it would be impossible for water to extract -more than quarter the heat of the fuel. Usually it was much less. The -next step was to make what is called a return tubular type in which the -heat of the burning gases is conveyed to the rear end of the boiler, and -then returned to the front end through tubes. - -Fig. 4 shows this construction. The head of the shell holds the ends of -a plurality of tubes, and the products of combustion pass through the -conduit, below the boiler to the rear end, and are conducted upwardly to -the tubes. As all the tubes are surrounded by water, it will absorb a -large amount of the heat as the gases move through, and before passing -out of the stack. - -[Illustration: _Fig. 4. Return Tubular Boiler._] - -[Illustration: _Fig. 5. Cornish, or Scotch Boiler._] - -The Cornish Boiler.--One of the most important inventions in the -generation of steam was the Cornish boiler, which for many years was the -recognized type for marine purposes. It had the advantage that a large -amount of water could be carried and be subjected to heat at all times. -Aside from that it sought to avoid the great loss due to radiation. - -It will be seen from an examination of Fig. 5 that the shell is made -very large, and its length does not exceed its diametrical measurement. -Two, and sometimes three, fire tubes are placed within the shell, these -tubes being secured to the heads. Surrounding these fire tubes, are -numerous small tubes, through which the products of combustion pass -after leaving the rear ends of the fire tubes. - -In these boilers the tubes are the combustion chambers, and are provided -with a grating for receiving the coal, and the rear ends of the tubes -are provided with bridge walls, to arrest, in a measure, the free exit -of the heated gases. - -These boilers would be very efficient, if they could be made of -sufficient length to permit the water to absorb the heat of the fuel, -but it will be seen that it would be difficult to make them of very -great length. If made too small diametrically the diameter of the fire -boxes would be reduced to such an extent that there would not be -sufficient grate surface. - -It is obvious, however, that this form of boiler adds greatly to the -area of the water surface contact, and in that particular is a great -improvement. - -[Illustration: _Fig. 6. Water Tube Boiler: End View._] - -The Water Tube Boiler.--In the early days of the development of boilers, -the universal practice was to have the products of combustion pass -through the flues or the tubes. But quick generation of steam, and high -pressures, necessitated a new type. This was accomplished by connecting -an upper, or steam drum, with a lower, or water drum, by a plurality of -small tubes, and causing the burning fuel to surround these tubes, so -that the water, in passing upwardly, would thus be subjected to the -action of the fuel. - -This form of boiler had two distinct advantages. First, an immense -surface of water could be provided for; and, second, the water and steam -drums could be made very small, diametrically, and thus permit of very -high pressures. - -In Fig. 6, which is designed to show a well known type of this -structure, A A, represent the water drums and B, the steam drum. The -water drums are separated from each other, so as to provide for the -grate bars C, and each water drum is connected with the steam drum by a -plurality of tubes D. - -It will thus be seen that a fire box, or combustion chamber, is formed -between the two sets of tubes D, and to retain the heat, or confine it -as closely as possible to the tubes, a jacket E is placed around the -entire structure. - -The ends of the water and steam drums are connected by means of tubes F, -shown in side view, Fig. 7, for the return or downward flow of the -water. The diagrams are made as simple as possible, to show the -principal features only. The structure illustrated has been modified in -many ways, principally in simplifying the construction, and in providing -means whereby the products of combustion may be brought into more -intimate contact with the water during its passage through the -structure. - -[Illustration: _Fig. 7. Water Tube Boiler: Side View._] - -As heretofore stated, this type of boiler is designed to carry only a -small quantity of water, so that it is necessary to have practically a -constant inflow of feed water, and to economize in this respect the -exhaust of the steam engine is used to initially heat up the water, and -thus, in a measure, start the water well on its way to the evaporation -point before it reaches the boiler. - -Various Boiler Types.--The different uses have brought forth many kinds -of boilers, in order to adapt them for some particular need. It would -be needless to illustrate them, but to show the diversity of structures, -we may refer to some of them by their characteristics. - -Compound Steam-Boiler.--This is a battery of boilers having their steam -and water spaces connected, and acting together to supply steam to a -heating apparatus or a steam engine. These are also made by combining -two or more boilers and using them as a feed water heater or a -superheater, for facilitating the production of steam, or to be used for -superheating steam. - -The terms _feed water heater and super heater_ are explained in chapter -III. - -Locomotive Steam-Boiler.--This is a tubular boiler which has a contained -furnace and ash pit, and in which the gases of combustion pass from the -furnace directly into the horizontal interior tubes, and after passing -through the tubes are conveyed directly into the smoke box at the -opposite ends of the tubes. The name is derived from the use of such -boilers on locomotive engines, but it is typical in its application to -all boilers having the construction described, and used for generating -steam. - -Vertical Steam-Boiler.--This is a form of construction in which the -shell, or both the shell and the tubes, are vertical, and the tubes -themselves may be used to convey the products of combustion, or serve -as the means for conveying water through them, as in the well known -water tube type. - -This form of boiler is frequently used to good advantage where it is -desired to utilize ground space, and where there is sufficient head -room. Properly constructed, it is economical as a steam generator. - -From the foregoing it will be seen that the structural features of all -boilers are so arranged as to provide for the exposure of the largest -possible area of water to a heated surface so that the greatest amount -of heat from the fuel may be absorbed. - - - - -CHAPTER III - -STEAM ENGINES - - -The first steam engine was an exceedingly simple affair. It had neither -eccentric, cylinder, crank, nor valves, and it did not depend upon the -pressure of the steam acting against a piston to drive it back and -forth, because it had no piston. - -It is one of the remarkable things in the history and development of -mechanism, that in this day of perfected steam engines, the inventors of -our time should go back and utilize the principles employed in the first -recorded steam engine, namely, the turbine. Instead of pressure exerting -a force against a piston, as in the reciprocating engine, the steam -acted by impacting against a moving surface, and by obtaining more or -less reaction from air-resistance against a freely discharging steam jet -or jets. - -The original engine, so far as we have any knowledge, had but one moving -part, namely, a vertical tubular stem, to which was attached a cross or -a horizontal tube. - -The Original Engine.--Figure 8 is a side view of the original engine. -The vertical stem A is pivoted to a frame B, and has a bore C which -leads up to a cross tube D. The ends of the tube D are bent in opposite -directions, as shown in the horizontal section, Fig. 9. - -[Illustration: _Fig. 8. The Original Engine._] - -[Illustration: _Fig. 9. Horizontal Section of Tube._] - -Steam enters the vertical stem by means of a pipe, and as it rushes up -and out through the lateral tubes D, it strikes the angles E at the -discharge ends, so that an impulse is given which drives the ends of the -tube in opposite directions. As the fluid emerges from the ends of the -tubes, it expands, and on contacting with the air, the latter, to a -certain extent, resists the expansion, and this reacts on the tube. -Thus, both forces, namely, impact and reaction, serve to give a turning -motion to the turbine. - -The Reciprocating Engine.--The invention of this type of engine is -wrapped in mystery. It has been attributed to several. The English -maintain that it was the invention of the Marquis of Worcester, who -published an account of such an engine about 1650. The French claim is -that Papin discovered and applied the principle before the year 1680. - -In fact, the first actual working steam engine was invented and -constructed by an Englishman, Captain Savery, who obtained a patent for -it in 1698. This engine was so constructed as to raise water by the -expansion and condensation of steam, and most engines of early times -were devoted solely to the task of raising water, or were employed in -mines. - -Atmospheric Engines.--When we examine them it is difficult to see how we -can designate them as steam engines. The steam did not do the actual -work, but a vacuum was depended on for the energy developed by the -atmospheric pressure. - -A diagram is given, Fig. 10, showing how engines of this character were -made and operated. A working beam A was mounted on a standard B, and one -end had a chain C on which was placed heavy weights D. Near this end was -also attached the upper end of a rod E, which extended down to a pump. - -[Illustration: Fig. 10. Steam-Atmospheric Engine.] - -The other end of the working beam had a chain F, which supported a -piston G working within a vertically-disposed cylinder H. This cylinder -was located directly above a boiler I, and a pipe J, with a valve -therein, was designed to supply steam to the lower end of the cylinder. - -A water tank K was also mounted at a point above the cylinder, and this -was supplied with water from the pump through a pipe L. Another pipe M -from the tank conducted water from the tank to the bottom of the -cylinder. - -The operation of the mechanism was as follows: The steam cock N, in the -short pipe J, was opened to admit steam to the cylinder, below the -piston. The stem of the steam cock also turned the cock in the water -pipe M, so that during the time the steam was admitted the water was -shut off. - -When the steam was admitted so that it filled the space below the -piston, the cock N was turned to shut off the steam, and in shutting off -the steam, water was also admitted. The injection of water at once -condensed the steam within the cylinder so a partial vacuum was formed. - -It will be remembered that as steam expanded 1700 times, the -condensation back into water made a very rarified area within the -cylinder, and the result was that the piston was drawn down, thus -raising both the weight D and also the pump rod E. This operation was -repeated over and over, so long as the cock N was turned. - -The turning of the stem of this cock was performed manually,--that is, -it had to be done by hand, and boys were usually employed for doing -this. When, later on, some bright genius discovered that the valve -could be turned by the machinery itself, it was regarded as a most -wonderful advance. - -The discovery of this useful function has been attributed to Watt. Of -this there is no conclusive proof. The great addition and improvements -made by Watt, and which so greatly simplified and perfected the engine, -were through the addition of a separate condenser and air pump, and on -these improvements his fame rests. - -From the foregoing it will be seen that the weight D caused the piston -to travel upwardly, and not the force of the steam, and the suction -produced by the vacuum within the cylinder did the work of actuating the -pump piston, so that it drew up the water. - -The Piston.--From this crude attempt to use steam came the next step, in -which the steam was actually used to move the piston back and forth and -thus actually do the work. In doing so the ponderous walking beam was -dispensed with, and while, for a long period the pistons were -vertically-placed, in time a single cylinder was used, and a crank -employed to convert the reciprocating into a circular motion. - -Fig. 11 shows a simple diagram of a steam engine, so arranged that the -operation of the valves may be readily understood. The cylinder A has a -steam chest B, which contains therein a slide valve C to cover the ports -at the ends of the cylinder. This figure shows the crank turning to the -right, and the eccentric D on the engine shaft is so placed, that while -the crank E is turning past the dead center, from 1 to 2, the slide -valve C is moved to the position shown in Fig. 12, thereby covering port -F and opening port G. - -[Illustration: _Fig. 11. Simple Valve Motion. First position._] - -[Illustration: _Fig. 12. Simple Valve Motion. Second position._] - -It will be seen that the slide valve is hollowed within, as at H, and -that the exhaust port I leads from this hollowed portion while the live -steam from the boiler enters through pipe J and fills the space K of -the chest. - -In Fig. 11 live steam has been entering port F, thus driving the piston -to the right. At the same time the exhaust steam at the right side of -the piston is discharging through the port G and entering the hollow -space within the slide valve. In Fig. 12 the conditions are reversed, -and now live steam enters port G, and the exhaust passes out through -port F. - -When the engine crank reaches the point 3, which is directly opposite 1, -the reverse action takes place with the slide valve, and it is again -moved to its original position, shown in Fig. 12. - -Importance of the Valve.--Every improvement which has been made in the -engine has been directed to the valve. The importance of this should be -fully understood. As the eccentric is constantly turning it is a -difficult matter to so arrange the valve as to open or close it at the -correct time, absolutely, and many devices have been resorted to to -accomplish this. - -Expanding the Steam.--As all improvements were in the direction of -economizing the use of steam, it was early appreciated that it would be -a waste to permit the steam to enter the cylinder during the entire -period that the engine traveled from end to end, so that the valve had -to be constructed in such a way that while it would cut off the -admission of steam at half or three-quarters stroke, the exhaust would -remain on until the entire stroke was completed. - -Some engines do this with a fair degree of accuracy, but many of them -were too complicated for general use. In the form of slide valve shown -the pressure of the steam on the upper side, which is constant at all -times, produces a great wearing action on its seat. This necessitated -the designing of a type of valve which would have a firm bearing and be -steam tight without grinding. - -Balanced Valve.--One of the inventions for this purpose is a valve so -balanced by the steam pressure that but little wear results. This has -been the subject of many patents. Another type also largely used in -engines is known as the _oscillating_ valve, which is cylindrical or -conical in its structure, and which revolves through less than a -complete revolution in opening and closing the ports. - -Rotary Valve.--The rotary valve, which constantly turns, is employed -where low pressures are used, but it is not effectual with high -pressures. This is also cylindrical in its structure, and has one or -more ports through it, which coincide with the ports through the walls -of the engine, as it turns, and thus opens the port for admitting live -steam and closing the discharge port at the same time or at a later -period in its rotation. - -Engine Accessories.--While the steam engine is merely a device for -utilizing the expansive force of steam, and thus push a cylinder back -and forth, its successful operation, from the standpoint of economy, -depends on a number of things, which are rarely ever heard of except by -users and engineers. - -Many of these devices are understood only by those who have given the -matter thorough study and application. To the layman, or the ordinary -user, they are, apparently, worth but little consideration. They are the -things, however, which have more than doubled the value of the steam -engine as a motor. - -Efficiency of Engines.--When it is understood that with all the -refinements referred to the actual efficiency of a steam engine is less -than 30 per cent. some idea may be gained of the value which the various -improvements have added to the motor. - -Efficiency refers to the relative amount of power which is obtained from -the burning fuel. For instance, in burning petroleum about 14,000 heat -units are developed from each pound. If this is used to evaporate water, -and the steam therefrom drives an engine, less than 4200 heat units are -actually utilized, the remaining 9800 heat units being lost in the -transformation from the fuel to power. - -[Illustration: _Fig. 13. Effective pressure in a Cylinder._] - -The value of considering and providing for condensation, compression, -superheating, re-heating, compounding, and radiation, and to properly -arrange the clearance spaces, the steam jackets, the valve adjustments, -the sizes of the ports and passages, and the governor, all form parts of -the knowledge which must be gained and utilized. - -How Steam Acts in a Cylinder.--Reference has been made to the practice -of cutting off steam before the piston has made a full stroke, and -permitting the expansive power of the steam to drive the piston the rest -of the way, needs some explanation. - -As stated in a preceding chapter the work done is estimated in foot -pounds. For the purpose of more easily comprehending the manner in which -the steam acts, and the value obtained by expansion, let us take a -cylinder, such as is shown in Fig. 13, and assume that it has a stroke -of four feet. Let the cylinder have a diameter of a little less than one -foot, so that by using steam at fifty pounds pressure on every square -inch of surface, we shall have a pressure of about 5000 pounds on the -piston with live steam from the boiler. - -In the diagram the piston moves forwardly to the right from 0 to 1, -which represents a distance of one foot, so that the full pressure of -the steam of the boiler, representing 5000 pounds, is exerted on the -piston. At 1 the steam is cut off, and the piston is now permitted to -continue the stroke through the remaining three feet by the action of -the steam within the cylinder, the expansive force alone being depended -on. - -As the pressure of the steam within the cylinder is now much less and -decreases as the piston moves along, we have taken a theoretical -indication of the combined pressure at each six inch of the travel of -the piston. The result is that we have the following figures, namely, -4000, 2700, 1750, 1000, 450 and 100. The sum of these figures is 10,000 -pounds. - -The piston, in moving from 0 to 1, moved one foot, we will say, in one -second of time, hence the work done by the direct boiler pressure was -5000 _foot pounds_; and since the piston was moved three feet more by -the expansion of the steam only, after the steam pressure was shut off, -the work done in the three seconds required to move the piston, was an -additional 5000 foot pounds, making a total of 10,000 foot pounds for -four seconds, 150,000 foot pounds per minute, or about 45 horse power. - -[Illustration: _Fig. 14. Indicating pressure Line._] - -This movement of the piston to the right, represented only a half -revolution of the crank, and the same thing occurs when the piston moves -back, to complete the entire revolution. - -Indicating the Engine.--We now come to the important part of engine -testing, namely, to ascertain how much power we have obtained from the -engine. To do this an indicator card must be furnished. A card to -indicate the pressure, as we have shown it in the foregoing diagram -would look like Fig. 14. - -The essential thing, however, is to learn how to take a card from a -steam engine cylinder, and we shall attempt to make this plain, by a -diagram of the mechanism so simplified as to be readily understood. - -[Illustration: _Fig. 15. Indicating the Engine._] - -In Fig. 15 we have shown a cylinder A, having within a piston B, and a -steam inlet pipe C. Above the cylinder is a drum D, mounted on a -vertical axis, and so geared up with the engine shaft that it makes one -complete turn with each shaft revolution. A sheet of paper E, ruled with -cross lines, is fixed around the drum. - -The cylinder A has a small vertical cylinder F connected therewith by a -pipe A, and in this cylinder is a piston H, the stem I of which extends -up alongside of the drum, and has a pointed or pencil J which presses -against the paper E. - -Now, when the engine is set in motion the drum turns in unison with the -engine shaft, and the pressure of the steam in the cylinder A, as it -pushes piston B along, also pushes the piston H upwardly, so that the -pencil point J traces a line on the ruled paper. - -It will be understood that a spring is arranged on the stem I in such a -manner that it will always force the piston H downwardly against the -pressure of the steam. - -Mean Efficiency.--We must now use a term which expresses the thing that -is at the bottom of all calculations in determining how much power is -developed. You will note that the pressure on the piston during the -first foot of its movement was 10,000 pounds, but that from the point 1, -Fig. 13, to the end of the cylinder, the pressure constantly decreased, -so that the pressure was not a uniform one, but varied. - -Suppose we divide the cylinder into six inch spaces, as shown in Fig. -13, then the pressure of the steam at the end of each six inches will be -the figures given at bottom of diagram, the sum total of which is -30,000, and the figures at the lower side show that there are eight -factors. - -The figure 10,000 represents, of course, two six inch spaces in the -first foot of travel. - -The result is, that, if we divide the sum total of the pressures at the -eight points by 8, we will get 3750, as the mean pressure of the steam -on the piston during the full stroke of the piston. - -In referring to the foot pounds in a previous paragraph, it was assumed -that the piston moved along each foot in one second of time. That was -done to simplify the statement concerning the use of foot pounds, and -not to indicate the time that the piston actually travels. - -Calculating Horse Power.--We now have the first and most important -factor in the problem,--that is, how much pressure is exerted against -the piston at every half revolution of the crank shaft. The next factor -to be determined is the distance that the piston travels in one minute -of time. - -This must be calculated in feet. Let us assume that the engine turns the -crank shaft at a speed of 50 revolutions a minute. As the piston travels -8 feet at each revolution, the total distance traveled is 400 feet. - -If, now, we have a constant pressure of 3750 pounds on the piston, and -it moves along at the rate of 400 feet per minute, it is obvious that -by multiplying these two together, we will get the figure which will -indicate how many pounds the steam has lifted in that time. - -This figure is found to be 1,500,000, which means foot pounds, as we -have by this means measured pressure by feet, or pounds lifted at each -foot of the movement of the piston. - -As heretofore stated, we must now use the value of a horse power, so -that we may measure the foot pounds by it. If we had a lot of wheat in -bulk, and we wanted to determine how much we had, a bushel measure would -be used. So with power. The measure, as we have explained, is 33,000, -and 1,500,000 foot pounds should give as a result a little over 45 horse -power. - -Condensation.--We now come to the refinements in engine -construction,--that which adds so greatly to the economy of operation. -The first of these is condensation. The first reciprocating engine -depended on this to do the actual work. In this age it is depended upon -simply as an aid. - -The first thing however that the engineer tries to do is to prevent -condensation. This is done by jacketing the outside of the cylinder with -some material which will prevent radiation of heat, or protect the steam -within from being turned back into water by the cool air striking the -outside of the cylinder. - -Atmospheric Pressure.--On the other hand, there is a time when -condensation can be made available. The pressure of air on every square -inch of surface is 14-3/4 pounds. When a piston moves along and steam is -being exhausted from the cylinder, it must act against a pressure of -14-3/4 pounds on every square inch of its surface. - -The problem now is to get rid of that back pressure, and the old type -engines give a hint how it may be done. Why not condense the steam -discharged from the engine cylinder? In doing so a vacuum is produced on -the exhaust side of the piston, at the same time a pressure is exerted -on its other side. - -The Condenser.--Thus the condenser is brought into existence, as an aid. -By jacketing condensation is prevented; it is fought as an enemy. It is -also utilized as a friend. It is so with many of the forces of nature, -where man for years vainly fought some principle, only to find, later -on, that a friend is more valuable than a foe, and to utilize a material -agency in nature is more economical than to fight it. - -Pre-heating.--The condenser does two things, both of which are of great -value to the economical operation of the engine. For the purpose of -rapidly converting the steam back into water as it issues from the -engine cylinder, water is used. The steam from the cylinder has a -temperature of 212 degrees and upwards, dependent on its pressure. - -Water, ordinarily, has a temperature of 70 degrees, or less, so that -when the steam strikes a surface which is cooled down by the water, it -is converted back into liquid form, but at a temperature less than -boiling water. The water thus converted back from the steam gives up -part of its heat to the water which cools the condenser, and the water -from the condenser, as well as the water used to cool the condenser, are -thus made available to be fed into the boiler, and thus assist in again -converting it into a steam. - -The economy thus lies in helping the coal, or other fuel, do its work, -or, to put it more specifically, it conserves the heat previously put -out by the coal, and thus saves by using part of the heat over again. - -Superheaters.--Another refinement, and one which goes to the very -essence of a heat motor, is the method of superheating the steam. This -is a device located between the boiler and the engine, so that the -steam, in its transit from the boiler to the engine, will be heated up -to a high degree, and in the doing of which the pressure may be -doubled, or wonderfully increased. - -This may be done in an economical manner in various ways, but the usual -practice is to take advantage of the exhaust gases of the boiler, in the -doing of which none of the heat is taken from the water in the boiler. - -The products of combustion escaping from the stacks of boilers vary. -Sometimes the temperature will be 800 degrees and over, so that if pipes -are placed within the path of the heated gases, and the supply steam -from the boiler permitted to pass through them a large amount of heat is -imparted to the steam from a source which is of no further use to the -water being generated in the boiler. - -Compounding.--When reference was made to the condensation of steam as it -issued from the boiler, no allusion was made to the pressure at which it -emerged. If the cylinder was well jacketed, so that the amount of -condensation in the cylinder was small, then the pressure would still be -considerable at the exhaust. Or, the steam might be cut off before the -piston had traveled very far at each stroke, in which case the exhaust -would be very weak. - -In practice it has been found to be most economical to provide a high -boiler pressure, and also to superheat the steam, but where it is not -superheated, and a comparatively high boiler pressure is provided, -compounding is resorted to. - -To compound steam means to use the exhaust to drive a piston. In such a -case two cylinders are placed side by side, one, called the high -pressure cylinder, being smaller than the low pressure cylinder, which -takes the exhaust from the high pressure. - -The exhaust from the second, or low pressure cylinder may then be -supplied to a condenser, and in that case the mechanism would be termed -a compound condensing engine. If a condenser is not used, then it is -simply a compound engine. - -Triple and Quadruple Expansion Engines.--Instead of using two cylinders, -three, or four, are employed, each succeeding cylinder being larger than -the last. As steam expands it loses its pressure, or, stated in another -way, whenever it loses pressure it increases in volume. For that reason -when steam enters the first cylinder at a pressure of say 250 pounds, it -may exhaust therefrom into the next cylinder at a pressure of 175 -pounds, with a corresponding increase in volume. - -To receive this increased volume, without causing a sensible back -pressure on the first cylinder, the second cylinder must be larger in -area than the first; in like manner when it issues from the exhaust of -the second cylinder at 125 pounds pressure, there is again an increase -in volume, and so on. - -[Illustration: _Fig. 16. Compound Engine._] - -Examine Fig. 16, which shows a pair of cylinders, A being the high, and -B the low pressure cylinders, the exhausts of the high pressure being -connected up with the inlets of the low pressure, as indicated by the -pipes, C D. - -The diagram does not show the valve operations in detail, it being -sufficient to explain that when the valve E in the pipe C is closed, the -valve F, at the other end of the cylinders, in the pipe D, is closed. -The same principle is employed in the triple and quadruple expansion -engines, whereby the force of the steam at each exhaust is put to work -immediately in the next cylinder, until it reaches such a low pressure -that condensation is more effective than its pressure. - -The diagram, as given, is merely theoretical, and it shows the following -factors: - -First: The diameter of each piston. - -Second: The area of each piston in square inches. - -[Illustration: Fig. 16a. Relative Piston Pressures.] - -Third: The steam pressure in each cylinder. - -Fourth: The piston pressure of each cylinder. - -It will be seen that an engine so arranged is able to get substantially -the same pressure in each of the second, third and fourth cylinders, as -in the first (see Fig. 16a), and by condensing the discharge from the -fourth cylinder a most economical use of steam is provided for. The -Steam Turbine.--We must now consider an entirely new use of steam as a -motive power. Heretofore we have been considering steam as a matter of -pressure only, in the development of power. It has been observed that -when the pressure of steam decreases at the same temperature it is -because it has a greater volume, or a greater volume results. - -[Illustration: Fig. 17. Changing Pressure into Velocity] - -When steam issues from the end of a pipe its velocity depends on its -pressure. The higher the pressure the greater its velocity. The elastic -character of steam is shown by its action when ejected from the end of a -pipe, by the gradually enlarging area of the discharging column. - -In a reciprocating engine the power is derived from the pressure of the -steam; in a turbine the power results from the impact force of the steam -jet. Such being the case velocity in the movement of the steam is of -first importance. - -Pressure and Velocity.--To show the effectiveness of velocity, as -compared with pressure, examine Fig. 17. A is a pipe discharging steam -at a pressure of 100 pounds. To hold the steam in the pipe would -require a pressure of 100 pounds against the disk B, when held at 1, the -first position. - -Suppose, now, the disk is moved away from the end of the pipe to -position 2. The steam, in issuing forth, strikes the disk over a larger -area, and in escaping it expands, with the result that its velocity from -1 to 2 is greater than the movement of the steam within the pipe that -same distance. - -[Illustration: _Fig. 18. Reaction against Air._] - -[Illustration: _Fig. 19. Reaction against Surface._] - -The disk is now moved successively to positions 3, 4, 5, and so on. If -we had a measuring device to determine the push against the disk at the -various positions, it would be found that there is a point at some -distance from the end of the pipe, at which the steam has the greatest -striking force, which might be called the focal point. - -A blow pipe exhibits this same phase; the hottest point is not at the -end of the pipe, but at an area some distance away, called the focal -point of heat. - -The first feature of value, therefore, is to understand that pressure -can be converted into velocity, and that to get a great impact force, -the steam must be made to strike the hardest and most effective blow. - -When a jet of steam strikes a surface it is diverted or it glances in a -direction opposite the angle at which it strikes the object. In -directing a jet against the blades of a turbine it is impossible to make -it strike squarely against the surface. - -[Illustration: Fig. 20. Turbine Straight Blades.] - -Let us assume that a wheel A, Fig. 20, has a set of blades B, and a -steam jet is directed against it by the pipe C. It will be seen that -after the first impact the steam is forced across the blades, and no -further force is transferred to them. - -Form of Blades.--The blades are therefore so curved, that the steam -after the first impact cannot freely pass along the blade, as it does on -a straight blade, but imparts on every element of the curved-back blade, -thereby giving up continually part of its speed to the blade. - -This is clearly shown in Fig. 21, where the pipe D ejects the stream of -steam against the concaved blades E. Many modifications have been made -in the shapes of these blades, all designed to take advantage of this -action. - -[Illustration: _Fig. 21. Curved Blades._] - -[Illustration: _Fig. 22. Compound Turbine._] - -Compounding the Jet.--We may extend the advantages gained by this form -of blades, and diverting the course of the jet, so that it will be -directed through a series of wheels, each of which will get the benefit -of the moving mass from the pipes. - -Such a structure is shown in Fig. 22, in which three bladed wheels A, B, -C, are caused to rotate, a set of stationary blades D, E, being placed -between the three moving wheels, but the stationary blades are disposed -in reverse directions. When the steam from pipes F, F, impinges against -the blades of the first wheel A, it is directed by the stationary blade -D to the next wheel B, and from the stationary blade E to the blades of -the next wheel C, thus, in a manner somewhat similar to the compounding -effect of the steam engine, utilizes the pressure which is not used at -the first impulse. - - - - -CHAPTER IV - -FUELS AND COMBUSTION - - -All fuels must be put into a gaseous state before they will burn. This -is true of coal as well as of hydro-carbon oils. - -Neither coal nor petroleum will burn in its native state, without the -addition of oxygen. This is absolutely necessary to support combustion. -Burning is caused by the chemical union of oxygen with such substances -as will burn. - -This burning process may be slow, and extend over a period of years, or -it may be instantaneous, in which latter case the expansion of the -heated gases is so great as to cause an explosion. When a sufficient -amount of oxygen has been mixed with a fuel to permit it to burn, a high -temperature is necessary to cause the immediate burning of the entire -mass. - -If such a temperature is not present the course of combustion is not -arrested, but it will, on its own account, start to oxydize, and -eventually be reduced to the same condition that would take place if -exploded by means of a flame. - -Solid Fuels.--The great fuels in nature are carbon and hydrogen, carbon -being the substance most widely known and depended upon. Hard coal, for -instance, is composed almost wholly of carbon; whereas soft coal has a -considerable quantity of hydrogen. - -As coal was formed by wood, which, through long process of time became -carbonized, it contains considerable foreign matter which will not burn, -forming ash. - -Liquid Fuels.--The volatile oils, however, have very little -non-combustible matter. Ordinary petroleum contains about 80 per cent, -of carbon, and from 12 to 15 per cent. of hydrogen, the residue being -foreign matter, all more or less susceptible of being consumed at high -temperatures. - -Combustion.--The term _combustion_, in its general sense, means the act -of burning; but in a larger and more correct application it refers to -that change which takes place in matter when oxygen unites with it. - -Oxygen is a wonderful element, and will unite with all known substances, -unlike all other elements in this respect. It may take years for it to -form a complete unity. Thus, wood, in time, will crumble, or rot, as it -is called. This is a slow process of combustion, brought about without -applying heat to it, the change taking place in a gradual way, because -oxygen unites with only a small portion of the wood. - -Oxidation.--Iron will rust. This is another instance of combustion, -called oxidation. When oxygen unites with a substance it may produce an -acid, or an alkali, or a neutral compound. When wood is burned it -produces an ash, and this ash contains a large amount of potash, or lye, -which is an alkali, or a salt. So when other substances are burnt the -result may be an acid, like sulphur, or it may be unlike either acid or -the alkali. - -The unity of oxygen with the food in the body is another instance of -oxidation, which produces and maintains the heat necessary for -existence. - -Carbon or hydrogen, as a fuel, are inert without oxygen, so that in -considering the evolution of a force which is dependent on heat, we -should know something of its nature, thereby enabling us to utilize it -to the best advantage. - -The Hydro-carbon Gases.--If petroleum, or gasoline, should be put into -the form of a gas, and as such be confined in a receiver, without adding -any oxygen, it would be impossible to ignite it. - -The character of the material is such that it would instantaneously -extinguish any flame. Now, to make a burning mixture, at least three -parts of oxygen must be mixed with one of the hydro-carbon, before it is -combustible. - -Oxygen and Atmosphere.--The atmosphere is not oxygen. Only one-fifth of -common air is oxygen, the residue being, principally, nitrogen, which is -not a fuel. To produce the proper aëration, therefore, at least fifteen -parts of air must be mixed with one part of hydro-carbon gas. - -The term _hydro-carbon_ is applied to petroleum, and its products, -because the elements carbon and hydrogen make up the largest part of the -oil, whereas this is not the case with most of the other oils. - -We are now dealing with a fuel such as is needed in _Internal Combustion -Engines_, and it is well to know some of the problems involved in the -use of the fuel, as this will give a better understanding of the -structure of the devices which handle and evolve the gases, and properly -burn them within the engine. - -Vaporizing Fuel.--As the pure liquid will not burn in that state the -first essential is to put it into a gaseous form, or to generate a vapor -from it. The vapor thus made is not a gas, in the true sense of that -term, but it is composed of minute globules of finely-divided particles -of oil. - -Nearly all liquids will vaporize if permitted to come into contact with -air. The greater the surface exposed to air the more rapidly will it -turn into a vapor. - -By forcibly ejecting the liquid from a pipe or spraying device, and -mingling air with it, evaporation is facilitated, and at the same time -the proper admixture of air is provided to make a combustible substance -the moment sufficient heat is brought into contact with it. - -This is what actually takes place in a gasoline engine, and all the -mechanism is built with this end in view. - -It has been the universal practice to make an explosive mixture of this -character, and then ignite it by means of an electric spark, but it is -now known that such a fuel can be exploded by pressure, and this needs -some explanation. - -Explosion by Compression.--The study of the compressibility of gases is -an interesting one. As we have previously stated, the atoms, comprising -the gases, are constantly moving among themselves with great rapidity, -so that they bombard the sides of the receiver in which they are -confined, and also contact with each other in their restless movements. - -When compression takes place the speed of the movements of the atoms is -greatly accelerated, the friction of their movements is increased, and -heat is evolved. As the pressure becomes greater the heat increases -until it is of such intensity that the gas ignites, and an explosion -follows. - -How Compression Heats.--The theory of the compressibility of gases may -be stated as follows: Let us assume that the temperature of the air is -70 degrees Fahrenheit, and we have a receiver which holds two cubic feet -of this air. - -If the contained air is now compressed to a volume of one cubic foot, -the temperature of two cubic feet is compressed into one cubic foot, and -there is now 140 degrees of heat within the receiver. - -If this cubic foot of air is again compressed to half its volume, the -temperature is correspondingly increased. While this it not absolutely -true in practice, owing to the immense loss caused by radiation, still, -it will enable the mind to grasp the significance of compression, when -the subject of heat is concerned. - -Elasticity of Gases.--The great elasticity of gases, and the perfected -mechanical devices for compressing the same, afford means whereby ten or -twenty atmospheres can be forced into a receiver, and thereby produce -pressures of several hundred pounds, which would mean sufficiently high -temperatures to ignite oils having the higher flash point. - -Advantages of Compression.--The compression system permits of the -introduction of a larger quantity of fuel than is usually drawn into the -cylinder, and thereby a greater and more efficient action is produced on -the piston of the engine on account of quicker combustion and therefore -higher gas pressures. - -The compression, however, rarely if ever exceeds six atmospheres or -about 90 pounds per square inch. - -_The Necessity of Compression._--There are two reasons why compression -is necessary before igniting it. First, because it is essential to put -sufficient gas in the cylinder to make the engine efficient. - -To illustrate: Suppose we have a cylinder capable of drawing in 150 -cubic inches of gas, and this is compressed down to 25 cubic inches, the -space then occupied by the gas would represent what is called the -clearance space at the head of the cylinder. To compress it to a greater -degree the clearance space might be made smaller, which could be done in -several ways, but whether the gas thus drawn in should be compressed to -30, or 25, or even 10 cubic inches, it is obvious that there would be -no more fuel in the cylinder in one case than in the other. As however -the mean effective pressure, which determines the efficiency of the -motor, increases with the compression pressure, the latter should be as -high as possible, but not so high that premature explosion takes place -owing to the heat created by compression. - -Second: The more perfect the mixture of the vaporized product with the -air, the more vigorous will be the explosion. The downward movement of -the piston draws in the charge of air and sprayed jet of gasoline, and -the only time for mixing it is during the period that it travels from -the carbureter through the pipes and manifold to the cylinder. - -Having in mind the statement formerly made that compression causes a -more rapid movement of the molecules of a gas, it is obvious that the -upward movement of the piston, in the act of compressing the gas has a -more positive action in causing an intimate mixture of the hydro-carbon -gases than took place when the gases were traveling through the pipes on -their way to the cylinder. - - - - -CHAPTER V - -THE INTERNAL COMBUSTION ENGINE - - -It will be observed that in a steam engine the heat is developed outside -of the cylinders and the latter used solely for the purpose of taking -the steam and utilizing it, by causing its expansion to push a piston to -and fro. - -We shall now consider that type of motor which creates the heat within -the cylinder itself and causes an expansion which is at once used and -discharged at the reciprocating motion of the piston. - -The original method of utilizing what is called _Internal combustion_ -Motors, was to employ a fixed gas. A _fixed_ gas is one which will -remain permanently in that condition, unlike a vapor made from gasoline. -The difference may be explained as follows: - -Fixed Gases.--If the vapor of gasoline, or petroleum, is subjected to a -high heat, upwards of 1500 degrees, it is so changed chemically, that it -will not again return to a liquid state. This is called _fixing_ it. Gas -is made in that way from the vapor of coal, and fixed, producing what -is called illuminating gas. - -Although the temperature of fixing it is fully three times greater than -is required to explode it, the fact that it is heated in closed retorts, -and oxygen is prevented from mixing with it, prevents it from burning, -or exploding. - -Gas Engines.--Such a gas has been used for many years in engines which -were usually of the horizontal type, and were made exceedingly heavy and -cumbrous, and provided with enormous fly wheels. Gases thus made are not -as rich as those generated direct from the hydro-carbon fuels, because, -being usually made from coal they did not have a large percentage of -hydrogen. - -Energy of Carbon and Hydrogen.--When a pound of carbon is burned, it -develops 14,500 heat units, and a pound of hydrogen over 52,000 heat -units. Assuming that 85 per cent. of a pound of petroleum is carbon, and -15 per cent. is hydrogen, the heat units of the carbon would be 12,225, -and the heat units of the 15 per cent. of hydrogen would be 12,800. The -combined value is, therefore, 25,025, which is almost double that of -coal gas. - -This fact makes the gasoline engine so much more efficient, and for the -same horse power the cylinders can be made smaller, and the whole -structure much lighter in every way. - -Gasoline motors are of two types, one in which an explosion takes place -at every revolution of the crank, called the _two-cycle_, and the other -the _four-cycle_, in which the explosion occurs at every other turn of -the crank. - -The terms _two-cycle_ is derived from the movement of the piston, as -that moves downwardly during the period when the crank is making a half -turn, and returns in its upward stroke when the crank completes the -turn, or that two half turns of the crankshaft complete the cycle. -Four-cycle engines have two such complete movements at each impulse, or -require four half turns of the crankshaft to complete the cycle. - -The Two-Cycle Type.--In order to clearly distinguish between this and -the four-cycle, it would be well to examine the diagram, Fig. 23. For a -clearer understanding the drawing is explained in detail. - -The cylinder A, within which the piston works, has a removable cap B, -and at its lower end a removable crank case C. The case is designed to -entirely close the lower end of the cylinder so that it is air tight, -for reasons which will be explained. - -The outer jacket, or casing D, at the upper end of the cylinder, is -designed to provide a space E, for the circulation of water, to cool -the cylinder during its working period. The crankshaft F passes through -the crank case, the latter having suitable bearings G for taking care of -the wear. - -[Illustration: _Fig. 23. Two-cycle. First Position._] - -The piston H is connected up with the rod I, the latter being hinged at -a point within the piston, as shown. The crank case has an inlet port, -provided with a valve which opens inwardly, so that when the piston -moves upwardly the valve will open and air will be drawn into the crank -case and space below the piston. - -At one side is a vertical duct K, which extends from a point directly -above the crank case, to such a position that when the piston is at its -lowest point gas can be discharged into the space above the piston. - -On the opposite side of the cylinder, and a little above the inlet port -of the duct K, is a discharge port M. The inlet port and the discharge -port, thus described, are both above the lower end of the piston when it -is at its highest point. - -The spark plug is shown at N. On the upper end of the piston, and close -to the side wall through which the inlet port K is formed, is an -upwardly-projecting deflecting plate O, the uses of which will be -explained in the description of its operation. - -Fig. 23 shows the piston at its highest point, and we will now assume -that ignition takes place, thus driving the piston downwardly until the -upper end of the piston has fully uncovered the discharge port M, as -shown in Fig. 24. This permits the exhaust to commence, and as the -piston proceeds down still further, so as to uncover the inlet port K, -the gas, which at the down stroke has been compressed in the space below -the piston, rushes in, and as it strikes the deflecting plate O, is -caused to flow upwardly, and thus helps to drive out the burnt gases -remaining at the upper end of the cylinder. - -[Illustration: Two-cycle Engine. - -Fig. 24. Second position. Fig. 25. Third position.] - -This action is called scavenging the cylinder, and the efficiency of -this type of engine is largely due to the manner in which this is done. -It is obvious that more or less of the unburnt gases will remain, or -that some of the unburnt carbureted air will pass out at each discharge, -and thus, in either case, detract from the power of the subsequent -explosion. - -As the piston now moves upwardly to complete the cycle, the piston -closes both of the ports, thus confining the gas which was previously -partly compressed, and as the piston proceeds the gas is still further -compressed until the piston again reaches the upward limit of its -motion. - -Advantages of the Two-Cycle Engine.--This kind of engine has several -distinct advantages. It has less weight than the four-cycle; it gives -double the number of impulses for a given number of revolutions of the -crankshaft; and it dispenses with valves, springs, cam-shafts, stems and -push rods. - -More or less danger, however, attends the operation of a two-cycle -engine, principally from the fact that an explosive mixture in a -partially compressed condition is forced into the space which the -instant before was occupied by a flame, and it is only because the -expansion of the burst gases at the previous charge has its temperature -decreased so far below the explosion point, that the fresh gas is not -ignited, although there have been occasions when explosions have taken -place during the upstroke. - -The Four-Cycle Engine.--The most approved type is that which is known as -the _four-cycle_. This will also be fully diagrammed so as to enable us -to point out the distinctive difference. - -[Illustration: Four-cycle Engine. - -Fig. 26. First position. Fig. 27. Second position.] - -Figs. 26 and 27 show sections of a typical four-cycle engine, in which -the inlet and the exhaust valves are mechanically operated. The cylinder -A is either cast with or separate from the crank case B, and has a -removable head C. The upper end of the cylinder has a water space formed -by the jacket D. - -The inlet port E and the discharge port F are both at the upper end of -the cylinder. The crank shaft G passes horizontally through the crank -case, and it is not necessary, as in the case of the two-cycle-engine, -to have the case closed tight. - -The piston H is attached to the connecting rod I, which is coupled to -the crank, as shown. The crank shaft has a small gear J, which meshes -with two gears of double size on opposite sides of the crank shaft, one -of the gears K, being designed to carry the cam L for actuating the stem -L´, which opens the valve M in the port that admits the carbureted air. - -[Illustration: Four-cycle Engine. - -Fig. 28. Third position. Fig. 29. Fourth position.] - -The other large gear N is mounted on a shaft which carries a cam O that -engages the lower end of a push rod P, to open the valve Q in the -discharge port F. It should be observed that the stems L´, P, are made -in two parts, with interposing springs R, so the valves may be firmly -seated when the stems drop from the cams. - -The spark plug S is located in the head, close to the inlet port. The -character of the igniting system is immaterial, as the object of the -present diagrams is to show the cycle and method of operating the engine -at each explosion, and to fully illustrate the manner in which it is -distinguished from the two-cycle type. - -A fly wheel is necessary in this as in the other type, and in practice -the two gear wheels, K, N, are placed outside of the case B, and only -the small gear, and the cam shafts, on which the cams are mounted, are -within the case. - -The operation is as follows: In Fig. 26 the piston is shown in a -position about to commence its downward movement, and we will assume -that the ignition has just taken place. Both valves M, Q, are closed, as -it will be noticed that the cams L, O, are not in contact with the lower -ends of the push rods. - -The explosion drives the piston down to the position shown in Fig. 27, -when the cam O begins to raise the stem P, and thus opens the discharge -valve Q, permitting the burnt gases to escape as the piston travels -upwardly to the position shown in Fig. 28. - -At this position the valve Q closes, and the cam L opens the inlet -valve M, so that as the piston descends the second revolution, the -carbureted air is drawn in until the crank has just turned at its lowest -limit of movement, as shown in Fig. 29. - -The upward stroke of the piston now performs the work of compressing the -carbureted air in the cylinder, and it is ready for the ignition the -moment it again reaches the position shown in Fig. 26. - -The Four Cycles.--The four distinct operations thus performed are as -follows: First, the explosion, and downward movement of the piston. -Second, the upward movement of the piston, and the discharge of the -burnt gases. Third, the down stroke of the piston, and the indrawing of -a fresh charge of carbureted air. Fourth, the upward movement of the -piston, and the compression of the charge of carbureted air. - -The order of the engine performance may be designated as follows: 1. -Impulse. 2. Exhaust. 3. Admission. 4. Compression. - -Ignition Point.--While the point of ignition, shown in the foregoing -diagrams, represents them as taking place after the crank has passed the -dead center, the firing, in practice, is so adjusted that the spark -flashes before the crank turns past the dead center. - -The reason for this will be apparent on a little reflection. As the -crank turns very rapidly the spark should be _advanced_, as it is -called, because it takes an interval of time for the spark to take -effect and start the explosion. If the sparking did not take place until -the crank had actually passed the dead center, the full effect of the -compression and subsequent explosion pressure would not be had. - -Advantage of the Four-Cycle Type.--The most marked advantage in the -four-cycle type is its efficiency. As it has one full stroke within -which to exhaust the burnt gases, the cylinder is in a proper condition -to receive a full value of the incoming charge, and there is no -liability of any of the unburnt gases escaping during the exhaust from -the previous explosion. - -The next important advantage of this type is in the fact that it can be -operated at a higher speed than the two-cycle type, and this is a great -advantage, notwithstanding the less number of impulses in the four-cycle -type. - -The Loss in Power.--The great disadvantage in all engines of this class -is the great loss resulting from their action. The explosion which takes -place raises the temperature to fully 2000 degrees of heat, and unless -some provision is made to keep the cylinder down to a much lower -temperature the engine would soon be useless. - -High temperatures of this character absolutely prevent lubrication, a -thing which is necessary to insure proper working. For this reason a -water jacket is provided, although there are engines which are cooled by -the action of air. - -In any event, the heat imparted to the cylinder is carried away and -cannot be used effectively, so that fully one-half of the power is -dissipated in this direction alone. - -The next most serious loss is in the escape of heat through the burnt -gases, which amounts to seventeen per cent. If the expansive force of -the burnt gases at the time of ignition is 250 pounds per square inch, -and at the time of the discharge it is fifty pounds, only four-fifths of -its power is effectively used. - -As, however, the discharge is against the air pressure of nearly fifteen -pounds per square inch, it is obvious that thirty-five pounds per inch -is driven away and lost. - -The third loss is by conduction and radiation, which amounts to fifteen -per cent. or more, so that the total loss from all sources is about -eighty-four per cent., leaving not more than sixteen per cent. of the -value of the fuel which is converted into power. - -Engine Construction.--In the construction of engines the utmost care -should be exercised in making the various parts. The particular -features which require special care are the valves, which should be -ground to fit tightly, the proper fitting of the piston rings, crank -shaft and connecting rod bearings as well as the accurate relining of -these bearings. - -[Illustration: Fig. 30. Valve Grinding.] - -Valve Grinding.--Fig. 30 shows a valve and valve seat. The valve has -usually a cross groove so that a screw driver in a drill stock may be -used to turn it and to exert the proper pressure. The finest emery -powder and a first class quality of oil should be used. The valve is -seated and after the oil and emery powder are applied the drill stock -is used to turn the valve. - -After twenty or thirty turns, wipe off the parts and examine the contact -edges, to see whether the entire surfaces are bright, which will -indicate that the valve fits true on its seat. Never overgrind. This is -entirely unnecessary. It is better also to rock the crank of the drill -stock back and forth, instead of turning it in one direction only. - -The Crank Shaft.--The crank shaft is the most difficult part of the -engine to build. It is usually made of a single forging of special steel -and the cranks and bearings are turned out of this, requiring the utmost -care. Formerly these were subject to breakage, but improved methods have -eliminated all danger in this direction. - -The Cams.--Notwithstanding the ends of the push rods are provided with -rollers to make the contact with the cams, the latter will wear, and in -doing so they will open the valves too late. The slightest wear will -make considerable difference in the inlet valve, and it requires care -and attention for this reason, in properly designing the cams, so that -wear will be brought to a minimum. - - - - -CHAPTER VI - -CARBURETERS - - -A carbureter is a device which receives and mixes gasoline and air in -proper proportions, and in which a vapor is formed for gasoline engines. - -The product of the carbureter is a mixture of gasoline vapor and air, -not a gas. A gas, as explained, is of such a character that it remains -fixed and will not stratify or condense. - -Functions of a Carbureter.--The function of a carbureter is to supply -air and gasoline by means of its adjustable features so as to make the -best mixture. The proportions of air and gasoline will vary, but -generally the average is fifteen parts of air to one of gasoline vapor. - -If there is too much gasoline, proportionately, a waste of fuel results, -as a great amount of soot is formed under those conditions. If there is -an excess of air the mixture, when ignited, will not have such a high -temperature, hence the expansive force is less, and the result is a -decrease of power. - -While it is possible to get a rapid evaporation from gasoline by -heating it, experience has shown that it is more economical to keep the -gasoline cool, or at ordinary temperatures, provided the carbureter is -properly constructed, because the vapor, if heated, when drawn into the -engine, will be unduly expanded, and less fuel in that case is drawn in -at each charge, and less power results. - -Rich Mixtures.--There are conditions under which rich mixtures are -advantageous. This is a mixture in which there is a larger percentage of -gasoline than is necessary for instantaneous combustion. For ordinary -uses such a mixture would not be economical. - -At low speeds, however, or when carrying heavy loads, it is desirable, -for the reasons that at a slow speed the combustion is slower. - -Rich mixtures are objectionable at high speeds because, as the -combustion is slow, incomplete combustion within the power stroke -results, the temperature of the gas at the end of the stroke is very -high, and this will seriously affect the exhaust valves. Furthermore, -there is likelihood of the gas continuing to burn after it is discharged -from the cylinder. - -Lean Mixtures.--Such a mixture is one which has a less amount of -gasoline than is necessary to make a perfectly explosive compound. For -high speeds a lean mixture is desirable, principally because it burns -more rapidly than a rich mixture. - -Types of Carbureters.--There are two distinct types of carbureters, one -which sprays the gasoline into a conduit through which air is passing, -and the other in which a large surface of gasoline is placed in the path -of the moving air column, which was originally used, but has been -absolutely replaced by the jet carbureters on account of their better -control features. - -It will be remembered that reference was made to the manner in which -vaporization takes place, this term being used to designate that -tendency of all liquids to change into a gaseous state. All carbureters -are designed with the object of mechanically presenting the largest -possible area of oil to the air, so that the latter will become -impregnated with the vapor. - -The Sprayer.--The best known type depends on dividing up the gasoline -into fine globules, by ejecting it from a small pipe or jet. The spray -thus formed is caught by the air column produced by the suction of the -engine pistons, and during its passage through the throttle and the -manifold, is in condition where a fair mixture of air and vapor is -formed, which will readily ignite. - -The Surface Type.--This form of carbureter provides a pool of gasoline -with a large surface, within the shell, so arranged that as the air is -drawn past the pool it must come into contact with the oil, and thus -take up the necessary quantity of evaporated gasoline for charging the -air. - -The _surface_ type has not been used to a large extent, but the -_sprayer_ is universally used, and of this kind there are many examples -of construction, each having some particular merit. - -Governing a Carbureter.--It is a curious thing that one carbureter will -work admirably with one engine, and be entirely useless in another. This -is due to several factors, both in the engine design and in the -carbureter itself. The quality of mixture that an engine will take -depends on its speed. The suction of the pistons depends on the speed of -the engine. - -If, at ordinary speed the carbureter gives a proper mixture, the throats -and passages through the pipes and manifold, as well as the valve which -discharges the gasoline, may be in a prime condition to do good work; -but when the pistons work at double speed the inrush of air may not -carry with it the proper amount of fuel; or, under those conditions, the -air may receive too great an amount of gasoline, proportionally. - -The latter is usually the case, hence provision must be made for such a -contingency, and we shall therefore take up the various features -essential in the construction of the carbureter, so as to show what -steps have been taken to meet the problems arising from varying speeds, -differences in the character of the fuel, regulating the inflow and -mixture of gasoline and air, and adjustments. - -[Illustration: _Fig. 31. Carbureter._] - -So many different types of carbureters have been devised, that it is -difficult to select one which typifies all the best elements of -construction. - -In Fig. 31 we have shown a well known construction, and which will -illustrate the features of the sprayer type to good advantage. The body -of the device, represented by A, has a flange by means of which it is -secured to the pipe which carries the carbureted air to the engine. The -lower end of this tubular body is contracted, as shown at B, so as to -form what is called a venturi tube. - -Exteriorly this contracted tube is threaded, as shown at C, so as to -receive thereon a threaded body D, the lower end of the body having an -enlarged disk-head E, integral therewith, and an upwardly-projecting -annular flange F is formed around this disk to receive and hold a -cylinder G, which constitutes the float and fuel chamber. - -The upper end of this cylinder rests against a seat cast with the body -A, and packing rings are placed at the ends of the cylinder to prevent -the oil from leaking out. Within the tubular body D is a vertical tube -H, integral with the disk head E, and oil is supplied to this tube -through ducts I, which communicate with the chamber within the reservoir -G. - -A drain cock is at the lower end of this tube, and an adjustable cap K -screws on the tubular stem of the drain tube, around which air is -admitted, the air passing upwardly through vertical ducts L, as shown, -and thus mixes with air at the contracted part of the venturi tube. - -A ring-like float N is placed within the glass chamber, and this is -adapted to engage with the inner end of a lever N´, this lever being -pivoted at O, within a side extension P of the carbureter shell. The -inner end of this lever has a link hinged thereto, the lower end of -which serves as a needle valve to close the ejecting orifice of the tube -L. - -The outer end of the lever N´ engages a shoulder on a -vertically-disposed needle valve Q, which has its point in the inlet -opening of the pipe R, through which gasoline is supplied to the glass -chamber. A spring T serves to keep the valve stem normally on its seat. - -Directly opposite this chambered extension P is another extension U, -also cast with the shell, through which is a vertical stem V. This stem -carries a downwardly-opening valve W, that seats against a plug, and a -spring X below the valve, serves to keep it against its seat, unless -there should be an extraordinarily heavy pull or suction. - -This is the auxiliary air inlet, and the lower spring is actuated only -when the engine is running at moderate speeds, but when running at high -speed and an additional quantity of air is required the upper spring Y -is compressed, and thus a much greater quantity of air is allowed to -pass in and mingle with the spray at the throttle valve Z. - -The throttle valve is mounted in the discharge opening, and is -controlled by a lever on the outside of the carbureter. - -The device operates as follows: Primary air enters the opening between -the cup K and the disk-head E, passing up into the space around the oil -tube H. As the spring T, around the needle valve Q, draws up the valve -from its seat, oil is permitted to flow in through the duct R and fill -the chamber, until the float engages with the inner end of the lever N, -and raises it, thus uncovering the ejecting end of the tube H, and at -the same time closing the inlet tube R. - -The suction from the engine then draws air through the primary duct, as -stated, and also an additional quantity through the secondary source, by -way of the valve W, this valve being so regulated as to supply the -requisite quantity. - -The auxiliary air source serves the purpose that means should be -provided to supply more than the ordinary amount of air, when running at -high speeds. - -From the foregoing it will be observed that a carbureter must be so -constructed that it will perform a variety of work. These are: First, -Automatic means for filling the float chamber when the gasoline goes -below a certain level. Second, Cutting off the supply of gasoline. -Third, Providing a primary supply of gasoline for spraying purposes. -Fourth, Furnishing an auxiliary air supply. Fifth, Throttling means in -the discharge opening. - -It is thus a most wonderful contrivance, and considering that all the -elements necessary to make it work satisfactorily are provided with -adjustable devices, it may be seen that to make it perform correctly -requires a perfect understanding of its various features. - -Requirements in a Carbureter.--In view of the foregoing it might be well -to know how to select a carbureter that is ideal in its operation. - -First. The adjustment of the auxiliary valve should be of such a -character that at the slowest speed the valve should not be lifted from -its seat. - -Second. It must be so arranged that it is not difficult to change the -relative amount of air and gasoline. - -Third. The floating chamber should be so arranged that the float will -act on the lever which lifts the valve of the injecting pipe, even -though the carbureter body should be tilted at an angle. This is -particularly important when the carbureter is used in automobiles. - -Fourth. The valves should be in such position that they are readily -accessible for cleaning or for examination. - -Fifth. The float should be so arranged that it is adjustable with -reference to the lever that it contacts with. - -Sixth. A gauze strainer should be placed at the gasoline inlet, and it -is also advisable to have a similar strainer above the mixing chamber, -beyond the throttle. - -Seventh. There should be no pockets at any point in the body to hold the -gasoline which might condense. - -Eighth. The body of the carbureter should be so constructed that every -part is easily accessible, and draining means provided so that every -particle of gasoline can be withdrawn. - -Ninth. Means for heating it, in case of cold weather. - -Size of the Carbureter.--The proper size of a carbureter for an engine -has been the subject of considerable discussion and experimenting. If -its passages are too large, difficulty will be experienced in starting -the engine, because the pulling draft through the primary will not be -sufficient to make a spray that will unite with the air. - -A carbureter too large will only waste fuel, even after the engine has -been cranked up so it will start. - -If the carbureter is too small the engine will not develop its required -output of power. While it might work satisfactorily at low speeds it -would be entirely inefficient at high speeds. - -Rule for Size of Carbureter.--In all cases the valve opening and -cylinder capacity in the engine should determine this. The size of the -opening of the carbureter outlet should be the same as that of the -engine valve, which is also the case where the carbureter supplies a -multi-cylinder, as there is only one valve open at the same time. - -It was formerly the custom to use a carbureter for each cylinder but the -practice has been abandoned, because it is obvious that a single -carbureter will, owing to the continuous suction, supply a mixture of -more nearly uniform character than two or more, even though they should -supply the mixture to a common manifold. - -The Throttle.--Much of the economy in running an engine depends on the -manipulation of the throttle. As an example, with a certain motor and -carbureter it will be found that for maximum speed the throttle should -be open about one-eighth of the way. The proper way, in starting the -engine, is to open the throttle fully half way, and to retard the -spark. As soon as the engine begins to run properly, the spark is -advanced and the throttle closed down to the required point. - -The engine speed may always be maintained by the throttle under a -constant varying load, by adjusting the throttle valve. A rich mixture -may be obtained by throttling the primary air supply. - -The throttle may also be a most effective means of economizing fuel when -the engine has a first class sparking device, as in that case the -throttle can be closed down to provide a very small opening. - -Flooding.--One of the most prevalent troubles in carbureters is the -liability to flood. This is usually caused by foreign matter getting -under or in the float valve, so that it will not properly seat. -Sometimes the mere moving of the float will dislodge the particle. - -Another cause of flooding is due, frequently, to an improperly-arranged -float, which, when the engine is inclined, will prevent improper seating -of the valve, and flooding follows. - -The greatest care should be exercised in seeing that the gasoline supply -is free from all impurities when it is poured into the tank. To strain -it is the best precaution, and it pays to be particular in this respect. -It is surprising to see the smallest speck, either stop the flow -entirely, or produce an overflow, either of which will cause a world of -trouble. - -Water is another element which has no place in a carbureter. An -indication of this is the irregular movement of the engine. The only -remedy is to stop and drain the carbureter. A few drops may cause all -the trouble. - -[Illustration: _Fig. 32. Carbureter._] - -Types of Carbureters.--In Fig. 32 we show another type of carbureter, -which is simple in construction, and has many desirable features. The -cylindrical body of the carbureter, A, has a downwardly-projecting -globular extension B, at one side of which is a flange C to secure it to -the pipe, and through this is the discharge opening D. This globular -extension serves as the mixing chamber. - -Within the cylindrical shell is an upwardly-projecting circularly-formed -extension E, and the top or cap F of the cylindrical body A has a -downwardly-projecting cylindrical rim G which overlaps the lower -circular extension E, and it is so constructed that a very thin annular -slit H is thus formed between the two parts, through which fuel oil -flows from the float chamber I into the space around the central tube J -which passes down through the two circular extensions E, G. - -This central tube J is designed for the auxiliary air supply. It extends -down to the globular base B, and has a valve K seated against its end. -The stem L of the valve is vertically-movable within an adjustable stem -M, and a helical spring N, capable of having its tension adjusted by the -stem M, bears upwardly against the valve so as to keep it normally -against the lower end of the tube J. - -The auxiliary air, therefore, passes down centrally through the tube J, -while the primary air supply passes through openings O, surrounding the -tube J, downwardly past the slitted opening H, and thence to the -discharge port D. - -Surrounding the tubular projections E, G, and within the float chamber -I, is the float P. This is designed to strike the bifurcated ends of a -lever Q, which is hinged near its outer end, as at R, and has its short -projecting end resting beneath the collar of a vertical needle valve S. - -This needle valve is vertically placed within a chambered extension T at -the side of the shell A, and its lower end rests within the opening of -the inlet U which supplies the gasoline to the chamber I. The upper end -of the valve stem passes through a plug V, through which is a vent hole -W. - -A spring X is used between the plug and the collar on the lower end of -the needle valve, so that the valve is kept on its seat thereby, unless -the gasoline in the chamber should fall so low as to cause the float to -rest on the inner end of the lever Q, when the needle valve would be -unseated thereby. - -All the parts of this device seem to be accessible, and it is presented -as an example of construction that seems to meet pretty nearly all of -the ideal requirements of a device for furnishing a perfect admixture. - -Surface Carbureter.--This type of carbureter also requires a float but -does not have secondary air inlet mechanism. It has one striking -advantage over the sprayer system, in the particular that the suction -of the engine is not depended upon to draw the gasoline from the float -chamber. It is much more sensitive to adjustment in the float level and -needle valve than the other type. - -[Illustration: _Fig. 33. Surface Carbureter._] - -The diagram, Fig. 33, shows a body A, somewhat bowl-shaped, with a -chambered extension, B, at one side, at the lower side of which is the -fuel inlet duct C. Directly above this duct the upper wall of the -extension has a plug D, the lower end of which carries therein the upper -end of a vertically-movable needle valve, E, the lower end of the valve -resting within the duct C. - -A float F within the bowl-shaped body is secured at one side to a lever -G, which is hinged at a point near the needle valve E, and the short end -of this lever connects with this needle valve in such a manner that as -the float moves upwardly the valve is seated, and when the level of the -fuel oil falls below a certain point the needle is lifted from its seat, -and oil is permitted to flow into the float chamber. - -The cap H of the float chamber has cast therewith a U-shaped tube, the -inlet end I being horizontally-disposed, while the discharge end J is -vertical. Directly above the lowest part of the bend in this tube, the -vertical dimension of the tube is contracted by a downwardly-projecting -wall K, so as to form a narrow throat L. - -Below this contracted point, the U-shaped tube has integral therewith a -downwardly-projecting stem M, the lower end of which passes through an -opening in the float chamber, and is threaded, so as to receive a nut, -by means of which the cap H may be firmly fixed to the float chamber. - -This stem M has a vertical duct N, which communicates with the float -chamber, and is provided with a drain plug O. Alongside of this duct is -a tube P which extends up into the U-shaped tube and is open at its -lower end so that the level of the gasoline within the bent tube cannot -extend above the end of this drain tube P. - -An adjustable valve stem Q passes through one side of the bent tube, the -lower end being pointed and adapted to regulate the inflow of gasoline -through the duct N, and into the U-shaped tube. - -A throttle valve R is placed in the discharge end of the U-shaped tube, -which is susceptible of regulation by means of a lever S. The diagram -shows the gasoline within the U-shaped tube, so that it is on a level -with the gasoline in the float chamber. - -In operation a sufficient amount of gasoline is permitted to enter the -float chamber so that a pool is formed in the bottom of the U-shaped -tube. When suction takes place the air rushes through the tube, at I, -down beneath the wall K, and in doing so it sweeps past the surface of -the pool at that point, absorbing a greater or less amount of the vapor. - -In order to adjust the device so that a smaller amount of the liquid -fuel will be exposed, the carbureter is adjusted so it will close the -needle valve before the level of the liquid is so high, and thereby a -less surface of oil is formed within the U-shaped tube. - -It is obvious that this type of carbureter, owing to the absence of the -secondary air-supply mechanism, can be readily regulated and all -adjustments made while running, while for automobile uses the lever S, -which controls the throttle, can be connected up with a dash-board -control. - - - - -CHAPTER VII - -IGNITION. LOW TENSION SYSTEM - - -Electricity, that subtle force, which manifests itself in so many ways, -is nevertheless beyond the power of man to see. The only way in which we -know of its presence is by the results produced by its movements, -because it can make itself known to our senses only by some form of -motion. - -The authorities regard light, heat and electricity as merely different -forms of motion. The most that can be done with such a force is to learn -the laws governing it. - -Magnetism.--This is a form of electricity. In fact, it is one of the -most universal manifestations, for without it electricity would be -useless. When the first permanent magnet was found at Magnesia, it was -not considered electricity. The sciences had not arrived at that point -where they were able to classify it as belonging to lightning and other -manifestations of that kind which we now know to be electricity. - -The Armature.--But magnetism can no more be seen than electricity -flowing through a wire. If a piece of metal has magnetism it will -attract a piece of iron or steel placed in close proximity, and thus we -are permitted to see the action. - -The lightning in the upper atmosphere burns the gases in its path. This -enables us to see, not the current, but its action,--the result produced -by its power. - -The electric current has many peculiar manifestations, the causes of -some of them being known and utilized. In the use of this medium for -igniting the fuel gas, many of the phases of electrical phenomena are -brought into play, and it is necessary, therefore, to know something of -the fundamentals of the science to enable us to apply it. - -Characteristics of Electricity.--When a current passes along a wire, it -does not describe a straight path, but it moves around the conductor in -the form of circles. The current is not confined wholly to the wire -itself, but it extends out a certain distance from it at all points. - -Magnetic Field.--Every part of a wire which is carrying a current of -electricity has, surrounding it, a magnetic field, of the same -character, and to all intents and purposes, of the same nature as the -magnetic field at the ends of a magnet. - -Elasticity.--This current has also something akin to elasticity. That -is, it surges to and fro, particularly when a current is interrupted in -the circuit. At the instant of breaking a current in an electric light -circuit there is a momentary flash which is much brighter than the -normal light, which is due to the regular flow of the current. - -This is due to the surging movement, or the elastic tension, in the -current. Advantage is taken of this characteristic, in making a spark. -This spark is produced at the instant that the ends of the wires are -separated. - -The Make and Break System.--No spark is caused by putting the two ends -together, or by making the connection, but only by breaking it, hence it -is termed the _make_ and _break_ method of ignition. - -When the connection is broken the current tries to leap across the gap, -and in doing so develops such an intense heat that the spark follows. As -a result of the high temperature it is necessary to use such a material -where the gap is formed that it will not be burned. For this purpose -platinum, and other metals are now employed. - -Voltage.--This plays an important part in ignition. Voltage is that -quality which gives pressure or intensity to a current. It is the -driving force, just as a head of water gives pressure to a stream of -water. - -High and Low Voltage.--A high tension current,--that is, one having a -high voltage, will leap across a gap, whereas a low voltage must have an -easy path. When the ends of a wire in a circuit are separated, air acts -as a perfect insulator between them, and the slightest separation will -prevent a low current from jumping across. - -This is not the case with a high tension current, where it will leap -across and produce the flash known as the _jump spark_. - -Low Tension System.--Two distinct types of ignition have grown out of -the voltage referred to, in which the _make_ and _break_ system uses the -low tension, because of its simplicity in the electrical equipment. - -Disadvantages of the Make and Break.--There is one serious drawback to -the extended use of this system, and that is the necessity of using a -moving part within the cylinder, to make and break the contact in the -conductor, as it is obvious that this part of the mechanism must be -placed within the compressed mixture in order to ignite it. - -Amperes.--A current is also measured by amperes,--that is, the quantity -flowing. A large conductor will take a greater quantity of current than -a small one, just as in the case of water a large pipe will convey a -greater amount of the liquid. - -Resistance.--All conductors offer resistance to the flow of a current, -and this is measured in _Ohms_. The best conductor is silver and the -next best is copper, this latter material being used universally, owing -to its comparative cheapness. - -Iron is a relatively poor conductor. Resistance can be overcome to a -certain extent, however, if a large conductor is used, but it is more -economical to use a small conductor which has small resistance, like -copper, than a heavy conductor, as iron, even though pound for pound the -latter may be cheaper. - -Direct Current.--There are two kinds of current, one which flows in one -direction only, called the _Direct_. It is produced in a dynamo which -has a pair of commutator brushes so arranged that as the armature turns -and its wires move through the magnetic fields of a magnet, and have -direction of the current alternate, these brushes will change the -alternations so the current will travel over the working conductors in -one direction only. - -Primary and secondary batteries produce a direct current. These will be -described in their appropriate places. - -Alternating Current.--This is a natural current. All dynamos originally -make this kind of current, but the commutator and brushes in the direct -current machine change the output method only. The movement of this -current is likened to a rapid to and fro motion, first flowing, for an -instant, to one pole, and then back again, from which the term -_alternating_ is derived. - -While the sudden breaking in a circuit will produce a spark with either -the direct or the alternating currents, the direct is usually employed -for the make and break system, since batteries are used as the -electrical source. - -On the other hand the jump spark method employs the alternating current, -because the high tension can be most effectively produced through the -use of _induction coils_, which will be explained in connection with the -jump spark method of ignition. - -Generating Electricity.--There are two ways to produce a current for -operating an ignition system, one by a primary battery, and the other by -means of a magneto, a special type of dynamo, which will be fully -explained in its proper place. - -Primary Battery.--As we are now concerned with the make and break -system, the battery type of generation, and method of wiring up the -same, should first be explained. - -Thus, in Fig. 34, a primary battery is shown, in which the zinc cell A -has an upwardly-projecting wing B at one side, to which the conductor is -attached; and within, centrally, is a carbon bar C. An electrolyte, -which may be either acid or alkali, must be placed within the cell. - -[Illustration: _Fig. 34. Dry Cell._] - -Making a Dry Cell.--The zinc is the negative, and the carbon the -positive electrode. The best material for the electrolyte is crushed -coke, which is carbon, and dioxide of manganese is used for this -purpose, and the interstices are filled with a solution of sal-ammoniac. - -The top of the cell is covered with asphaltum, so as to retain the -moistened material and the liquid within the cell, and thus constituted, -it is called a _dry cell_. - -Energy in a Cell.--A battery is made up of a number of these cells. Each -cell has a certain electric energy, usually from one and a half to one -and three-quarter volts, and from twenty-five to forty amperes. - -The amperage of a cell depends on its size, or rather by the area of the -electrodes; but the voltage is a constant one, and is not increased by -the change, formation, or size of the electrodes. - -For this reason the cells are used in groups, forming, as stated, a -battery, and to get efficient results, various methods of connecting -them up are employed. - -[Illustration: _Fig. 35. Series Connection._] - -Wiring Methods.--As at least six cells are required to operate a coil, -the following diagrams will show that number to illustrate the different -types of connections. - -Series Connection.--The six cells, Fig. 35, show the carbon electrodes -A, of one cell, connected by means of a wire B with the zinc electrode -wing C of the next cell, and so on, the cell at one end having a -terminal wire D connected with the zinc, and the cell at the other end a -wire E connected with the carbon electrode. - -The current, therefore, flows directly through the six cells, and the -pressure between the terminal wires D, E, is equal to the combined -pressure of the six cells, namely, 1-1/2 × 6, which is equal to 9 volts. -The amperage, however, is that of one cell, which, in these diagrams, -will be assumed to be 25. - -[Illustration: _Fig. 36. Multiple, or Parallel Connection._] - -Parallel Connection.--Now examine Fig. 36. In this case the carbon -electrodes A are all connected up in series, that is, one following the -other in a direct line, by wires B, and the zinc electrodes C, are, in -like manner, connected up in series with each other by wires D. The -difference in potential at these terminals B, D, is the same as that of -a single cell, namely, one and a half volt. - -The amperage, on the other hand, is that of the six cells combined, or -150. This method of connecting the cells is also called _parallel_, -since the two wires forming the connections are parallel with each -other, and remembering this it may be better to so term it. - -Multiple Connections.--This is also designated as _series multiple_ -since the two sets of cells each have the connections made like the -series method, Fig. 35. The particular difference being, that the zinc -terminals of the two sets of cells are connected up with one terminal -wire A, and the carbon terminals of the two sets are joined to a -terminal B. - -[Illustration: _Fig. 37. Series-Multiple Connection._] - -The result of this form of connection is to increase the voltage equal -to that of one cell multiplied by the number of cells in one set, and -the amperage is determined by that of one cell multiplied by the two -sets. - -Each set of cells in this arrangement is called a battery, and we will -designate them as No. 1, and No. 2. Each battery, therefore, being -connected in series, has a voltage equal to 4-1/2 volts, and the -amperage 50, since there are two batteries. - -Now the different arrangement of volts and amperes does not mean that -the current strength is changed in the batteries or in the cells. If -the pressure is increased the flow is lessened. If the current flow, or -the quantity sent over the wires is increased, the voltage is -comparatively less. - -Watts.--This brings in another element that should be understood. If the -current is multiplied by the amperes a factor is obtained, called -_Watts_. Thus, as each cell has 1-1/2 volts and 25 amperes, their -product is 37-1/2 watts. - -To show that the same energy is present in each form of connection let -us compare the watts derived from each: - -Series connection: 9 volts × 25 amperes, equal 225 watts. - -Parallel connection: 1-1/2 volts × 150 amperes, equal 225 watts. - -Series Multiple connection: 4-1/2 volts × 50 amperes, equal 225 watts. - -From the foregoing, it will be seen that the changes in the wiring did -not affect the output, but it enables the user of the current to effect -such changes that he may, for instance, in case a battery should be -weak, or have but little voltage, so change connections as to -temporarily increase it, although in doing so it is at the expense of -the amperage, which is correspondingly decreased. - -It would be well to study the foregoing comparative analysis of the -three forms of connections, so far as the energy is concerned, because -there is an impression that increasing the voltage, is adding to the -power of a current. It does nothing but increase the pressure. There is -not one particle of increase in the energy by so doing. - -[Illustration: _Fig. 38. Circuit Testing._] - -_Testing a Cell._--The cells should be frequently tested, to show what -loss there is in the amperage. This is done by putting an ammeter in the -circuit. If a meter of this kind is not handy, a good plan is to take -off one of the wire connections, and snap the wire on the terminal, and -the character of the spark will show what energy there is in the cell. - -Testing With Instruments.--The method of testing with voltmeter and -ammeter, is shown in Fig. 38. The voltmeter is placed in a short circuit -between the two terminal wires, whereas the ammeter is placed in circuit -with one of the wires. The reason for this is that the voltmeter -registers the pressure, the power, or the difference of potential -between the two sides of the cell, and the ammeter shows the quantity of -current flowing over the wire. - -In practice batteries are not used continuously for igniting. They are -temporarily employed, principally for starting, because their continued -use would quickly deplete them. - -[Illustration: _Fig. 39. Make and Break, with Battery._] - -Simple Battery Make and Break System.--In order to show this method in -its simplest form, examine Fig. 39, which diagrams the various parts -belonging to the system. - -We have illustrated it with two cylinders, portions of the heads being -shown by the outlines A, A. B, B represent terminals which project into -the cylinders, and are insulated from the engine heads. Through the -sides of the engine heads are rock shafts C, the ends within the -cylinder having fingers D which are adapted to engage with the inner -ends of terminals B, B. - -On the ends of the rock shafts outside of the cylinders, they are -provided with levers E, E, one end of each being attached to a spring F, -so that the tension of the spring will normally keep the upper end of -the finger D in contact with the terminal B. The cut shows one finger -engaging with B, and the other not in contact. - -The other end of the lever E rests beneath a collar or shoulder G on a -vertical rod H. The lower end of this rod engages with a cam I on a -shaft J, and when the cam rotates the rod drops off the elevated part of -the cam, and in doing so the shoulder G strikes the end of the lever E -and causes the finger to rapidly break away from the terminal B, where -the spark is produced. - -To Advance the Spark.--For the purpose of advancing or retarding the -spark, this rod has, near its lower end, a horizontally-movable bar K, -which may be moved to and fro a limited distance by a lever L, this -lever being the substitute in this sketch of the lever on the steering -wheel of an automobile. - -The spark is advanced or retarded by causing the lower end of the rod H -to be moved to the left or to the right, so that it will drop off of -the raised portion of the cam earlier or later. - -The wiring up is a very simple matter. The battery M has one end -connected up with one terminal of a switch N, while the other terminal -of the switch has a wire connection with the terminal plugs B, B, in the -cylinder heads. - -The other end of the battery is connected with the metal of the engine, -which may be indicated by the dotted line O which runs to the rock shaft -C, and thus forms a complete circuit. - -The operation is as follows: When the key P of the switch is moved over -so that it contacts with the terminal N, the battery is thrown into the -circuit, and the current then passes to the plug B of the first -cylinder, as the finger D in that cylinder is in contact with that -terminal, and it passes along the finger D, and rock-shaft C, to the -metal of the engine, and passes thence to the battery, this course being -indicated by the dotted line O. - -At the same time, while cylinder No. 2 is also connected up with the -battery, the shoulder of the rod H has drawn the finger D from its -contact with the plug B, hence the current cannot pass in that -direction. - -As the cam I, of cylinder No. 1, turns in the direction of the arrow, -the rod drops down and suddenly makes a break in the terminal of this -cylinder, causing the ignition, to be followed by a like action in No. -2. - -The Magneto in the Circuit.--To insure the life of the battery, so that -it may be in service only during that period at the starting, when the -magneto is not active, the latter is so placed in the circuit, that, at -the starting, when, for instance, the automobile is being cranked, it is -cut out by the switch on the dash board. - -[Illustration: Fig. 40. Make and Break, with Magneto.] - -In Fig. 40, a simple two-pole switch is used. With the magneto it is -necessary to have a three-point switch, R, and a plain coil S is placed -between the switch and battery. - -One side of the magneto T is connected by wire U with one of the points -of the switch R, and the other side of the magneto is connected with -the metal of the engine, which is indicated by the dotted line V. - -In all other respects the mechanism is the same. The starting operation -has been explained with reference to the preceding figure, and when the -engine has picked up, and is properly started, the switch bar is thrown -over so it contacts with the point connected up with the wire U leading -to the magneto. - -This, of course, cuts out the battery, and the engine is now running on -the magneto alone. The object of the coil S is to oppose a rapid change -of the current at the moment of the interruption. The coil induces a -counter current the moment the break is made, and as the current -continues to flow for a very short period after the break a spark of -greater intensity is produced than if the circuit should be permitted to -go from the battery to the sparker directly, as in the previous -illustration. - -The best spark is produced by quickly making the break between the -points B, D, so that particular attention has been given to mechanism -which will do this effectively. - -Magneto Spark Plug.--One of the devices to obviate the difficulty of -providing moving mechanism outside of the engine cylinder, is shown in -Fig. 41. In this the coil A is connected with a terminal B at the head -of the device and the other is connected to the plug C which screws into -the cylinder head. - -[Illustration: _Fig. 41. Magneto Spark Plug._] - -Within the core is a pivotally-mounted lever D, the upper end E of which -is attracted by the tubular metallic core F, and the lower end having a -contact point G, which is adapted to engage with a stationary point H. - -The pivot I, on which the lever D is mounted, provides a means whereby -the lever swings, and a spring J is so arranged that when the lower end -of the lever is disengaged from the contact, the spring will return it -to its normal position. - -In its operation when a contact is formed by the timing device of the -magneto, so as to give a spark, the circuit passes to the terminal B, -coil A, and plug C, thus forming a complete circuit. This energizes the -core A, pulling the upper end of the lever, and at the same time causes -the lower end to disengage the two contacts G, H, which breaks the -circuit and produces a spark. - -The breaking of the circuit deënergizes the core, and the spring again -draws the lever back to its normal position, ready for the next -completion of the circuit by the timing device. - -Such an arrangement is as simple as the spark plug usually employed in -the use of the high tension system, although it is more expensive than -the plug. - - - - -CHAPTER VIII - -IGNITION. HIGH TENSION - - -This system is used to the largest extent, so that we ought to have a -full explanation of the devices which are required to do the work. While -magnetos are used with the low tension system, for the reasons stated, -they are especially necessary with the _Jump Spark_ method. - -Magnetos.--The most important element in this system is the magneto, so -we shall try and make the subject as explicit as possible. As stated, a -magneto is a special type of dynamo which will now be explained. For -this purpose it will be necessary to show the elementary operation of an -alternating current dynamo. - -Alternating Current.--In Fig. 42 A is a bar of soft iron, around which -is a coil of wire B, the wire being insulated, so that it will not touch -the bar. There is no magnetism in this bar, and this simple form of -structure is shown, merely to represent what is called the _field_ of a -dynamo. - -The object of the coil of wire is to make a magnet of the bar, for the -moment a current is sent over the wire, a magnet is formed, and the -magnetism leaves the bar the moment the current ceases to flow. If this -bar should be of hard steel it would retain the magnetism. - -[Illustration: _Fig. 42. Illustrating Alternating Current._] - -[Illustration: _Fig. 43. Alternating Current. Second position._] - -Now, the primary difference between the magneto and the dynamo, is that -this field bar is a permanent magnet in the magneto, whereas the field -is only a temporary magnet in the dynamo. This should always be kept in -mind. - -The end of a magnet, whether it is a temporary one, or permanent, has a -magnetic field of force at the ends as well as at all parts of it, -exterior to the surface of the bar. Such a field is indicated, and in -the dynamo, no such field exists unless a current is passing over the -wire B, which is called the _field winding_. - -The U-shaped piece of metal C represents the armature. It is shown -hinged to the top of two posts, for clearness in understanding, and is -adapted to turn to the right, and in turning the loop passes the end of -the field bar B, and passes through the magnetic field which is -indicated by the dotted lines D. - -[Illustration: _Fig. 44. Alternating Current. Third position._] - -Now, if the loop is simply permitted to remain in the position shown in -Fig. 42, a current would flow through the loop, this transference of the -current being called induction, and this characteristic of the flow of -electricity will be explained and its utility explained. - -Cutting Lines of Force.--The loop will now be turned to the right so -that it passes the magnetic field and goes beyond it in its revolution. -This motion of passing the armature through the magnetic field is called -_cutting_ the _lines of force_. While the loop was lying within the -magnetic field, and also when it was moving through the field, the -current set up in the loop flowed in the direction of the darts F, or to -the right, through the pivots D. - -In Fig. 43 the loop is shown as having made a quarter turn, and it is -now vertical, or at right angles to its former position. The loop in -thus passing away loses its force, until it reaches the position shown -in Fig. 44, when there is a surging back of the current to the opposite -direction, as indicated by the arrows. - -[Illustration: _Fig. 45. Alternating Current. Fourth position._] - -When the loop reaches the lowest position, shown in Fig. 45, it again -begins to get the influence of the magnetic field, and a reversal back -to its former direction takes place, this surging movement back and -forth being due to the reversal of the polarity in the coil brought -about by the position in which it is placed relative to the magnetic -field. - -It is now an easy matter to connect the ends of the loop with wire -conductors. This is shown in Fig. 46, where a small metal wheel G is -placed on each end of the spindle, and in having a strip of metal -bearing H on the wheel. These are not commutator brushes, but are merely -wiping brushes to take the current from the turning parts. Wires I -connect with these wiping bars, and through them the current is -transmitted to perform the work. - -[Illustration: _Fig. 46. Making the Circuit._] - -Plurality of Loops.--The dynamo may have a plurality of loops, which are -called _coils_, and there may be a single magnet or any number of -magnets. Instead of driving these coils past the face of the magnet, or -magnets, the latter may be driven past the coils. In fact with most of -the alternating current machines the fields are the rotating parts and -the armatures, or the coils, are fixed. - -The voltage is increased if the coils have a large number of turns on -the armature, and also if the armature, or the turning part, is speeded -up. Voltage will also be higher if larger or more powerful magnets are -used in the magnetos. - -The Electro-Magnet.--The permanent magnet, such as is used in the -magneto, is distinguished by the fact that it contains a permanent -charge of magnetism, but this is not an _electro-magnet_. This is a -magnet made of soft iron, so it will be readily demagnetized. While not -shown in the diagrams, an iron core may be placed within the loop or -coil, and this is done in all dynamos, because the iron core acts as a -carrier of the magnetism, concentrating it at the center, because it is -a much better conductor than air. - -[Illustration: _Fig. 47. The Dynamo._] - -[Illustration: _Fig. 48. The Magneto._] - -The Dynamo Form.--Consult the diagram, Fig. 47. The iron heads A -represent the bar in the previous diagrams, and B the wire around the -bar. C is the armature, which in this case represents a number of loops, -or coils, and D is the commutator, which is used in the direct current -machine to correct the alternations referred to in the previous -diagrams, so as to send the current in one direction only, the -commutator brushes E being used to carry off the current for use. - -The Magneto Form.--The metal loop F, in Fig. 48, being a permanent -magnet, the armature, G, formed of a plurality of loops, has no field -wires to connect with it, as in the case of the dynamo. - -Advantage of the Magneto.--The magneto has a pronounced advantage over -the dynamo, as a source of power for ignition purposes, in the -particular that the strength of the magnetic field is constant. In a -dynamo this varies with the output, because when used on an automobile -where the speed is irregular, the voltage will vary. The voltage of the -magneto is a constant one, and is thus better adapted to meet the needs -of ignition. - -Induction Coil.--The induction coil is a device which is designed to -produce a very high voltage from a low tension, so that a current from -it will leap across a gap and make a hot spark. - -We stated in a previous section that a current leaps across from one -conductor to another, so that electricity can be transferred from a -wire to another not touching it, by means of induction. - -Look at Fig. 49, which represents two wires side by side. The current is -flowing over one wire A, and by bringing wire B close to A, but not -touching it, a current will be induced to leap across the gap and the -wire B will be charged. If the ends of the wire B are brought together, -so as to form a circuit, and a current detector is placed in the circuit -it will be found that a current is actually flowing through it, but it -is now moving in a direction opposite to the current flowing through A. - -[Illustration: _Fig. 49. Current by Induction._] - -Changing the Current.--But we have still another thing to learn. If the -two wires are not of the same thickness it would not prevent the current -from leaping across, but another astonishing thing would result. - -First, we shall use a wire B double the thickness of wire A. If now, we -had an instrument to test the voltage and the amperage, it would be -found that the voltage in B is less than that in A, and also that the -amperage is greater. - -Second, if the conditions are reversed, and the wire A is thicker than -B, the latter will have an increase of voltage, but a lower ampere flow -than in A. - -Now this latter condition is just what is necessary to give a high -tension. Voltage is necessary to make a current leap across a gap. By -this simple illustration we have made an induction coil which may be -used for making a high tension jump spark. - -Construction of a Coil.--Two wires side by side do not have the -appearance of a coil, and even though such an arrangement might make a -high tension current, it would be difficult to apply. To put the device -in such a shape that it can be utilized, a spool is made, as shown in -Fig. 50. - -[Illustration: Fig. 50. Induction Coil.] - -This spool A has a number of layers of thick, insulated wire B first -wound around it, the layers being well insulated from each other, and -the opposite ends brought out at one end or at the opposite ends, as -shown at C, D. On this is a layer of finer wire, also insulated, this -wire E having its terminals also brought out at the ends of the spool, -and after the whole is thus wound, the outside of the coil is covered -with a moisture proof material. - -The Primary Coil.--The winding of thick wire is called the _primary_ -coil. The current from the battery or the electric generator is led to -this inner coil. - -[Illustration: _Fig. 51. Typical Induction Coil._] - -The Secondary Coil.--The fine wire wrapping represents the secondary -coil, which is raised to a high voltage, and this actuates the sparking -mechanism. - -In the art it is customary to illustrate the various contrivances by -certain conventional forms. Fig. 51 shows the manner of designating an -induction coil in a diagram, in which the heavy zig-zag line indicates -the primary, and the lighter zig-zag lines the secondary coil. - -[Illustration: _Fig. 52. Contact Maker._] - -Contact Maker.--A simple little device used in the primary circuit of an -induction coil, is known as a _contact maker_. This, as shown in Fig. -52, is merely a case A, through which is a shaft B that carries within -the shell a cam C. A spring finger D has its free end normally bearing -against the cam, and when the nose on the cam moves out the spring -finger, the latter is moved outwardly so it contacts with a plug E in -the side wall of the case, although it is insulated therefrom. This -contact establishes a current through the plug, spring finger and case. - -The diagram, Fig. 53, illustrates the principles of construction and -arrangement of a high tension jump spark ignition, in which the -electrical source is a battery actuating an induction coil. - -High Tension With Battery and Coil.--The battery A has one side -connected up by wire B with one terminal of the primary C in the -induction coil, and the other side of the battery has a wire D leading -to the contact maker. A switch E is placed in the line of this wire. - -[Illustration: _Fig. 53. Typical Circuiting, Jump Spark Ignition._] - -The other terminal of the primary has a wire F leading to the insulated -contact plug G of the contact maker. This completes the generating -circuit. The cam H is on a shaft I, which travels one half the speed of -the engine shaft. - -One side of the secondary coil J has a wire K leading to the spark plug, -while the other terminal of the secondary has a wire L which is grounded -on the engine M. - -When the nose of the cam pushes over the spring finger and closes the -cam, the circuit through the finger flows through the primary coil and -excites the secondary. When the cam again immediately breaks the circuit -a high tension current is momentarily induced in the secondary, so that -the current leaps the gap in the spark plug and makes the spark. - -[Illustration: _Fig. 54. Metallic Core, Induction Coil._] - -Metallic Core for Induction Coil.--In the previous description of the -induction coil it was stated that the spool might be made of wood. These -coils are also provided with metal cores, which can be used to make what -is called a vibratory coil. - -The Condenser.--A necessary addition to the circuiting provided by an -induction coil, is a _condenser_. This is used in the primary circuit to -absorb the self-induced current of the primary and thus cause it to -oppose the rapid fall of the primary current. - -The condenser is constructed of a number of tinfoil sheets, of suitable -size, each sheet having a wing at one end, and these sheets are laid on -top of each other, with the wings of the alternate sheets at opposite -ends. Very thin sheets of waxed paper are placed between the tin foil -sheets so that they are thus insulated from each other. - -The wings at the ends are used to make connections for the conducting -wires. The device is not designed to conduct electricity, but to act as -a sort of absorbent, if it might so be termed. The large surface affords -a means where more or less of the current moves from the conductor at -one end to the conductor at the other end, and as it is designed to -absorb a portion of the current in the line it is merely bridged across -from one side of the circuit to the other. - -[Illustration: _Fig. 55. Condenser._] - -The diagram, Fig. 55, represents the conventional form of illustrating -it in sketching electrical devices. - -Operation of a Vibrator Coil.--The illustration, Fig. 56, shows the -manner in which a vibrator coil is constructed and operated. The coil -comprises a metal core A, the primary winding B being connected at one -terminal, by a wire C, with a post D, and the other terminal by a wire E -with one side of a battery F. A switch G is in the line of this -conductor. - -[Illustration: _Fig. 56. Vibrator Coil and Connections._] - -The post D holds the end of a vibrating spring H, which has a hammer H´ -on its free end, which is adapted to contact with the end of the metal -core A, but is normally held out of contact, so that it rests against -the end of an adjusting screw I which passes through a post J. - -The post J is connected up with the battery by a wire K, and a wire L -also runs from the wire K to the conductor C, through a condenser M. - -The secondary coil N, has the outlet wires O, P, which run to the spark -plug Q on the engine. - -The operation is as follows: When the switch G closes the circuit, the -battery thus thrown in the primary coil magnetizes the core A, and the -hammer H´ is attracted to the end of the core, thus breaking the circuit -at the contact screw I. The result is that the core is immediately -demagnetized, and the spring H draws the hammer back to be again -attracted by the core which is again magnetized, so that the hammer on -the vibrator arm H goes back and forth with great rapidity. - -From the foregoing explanations it will be understood how the primary -induces a high tension current in the secondary, and in order that the -spark may occur at the right time, a _timer_ for closing and opening the -primary circuit must be provided. By this means an induced high tension -current is caused to flow at the time the spark is needed in the cycle -of the engine operation. - -_The Distributer._--The distributer is a timing device which controls -both the primary and the secondary currents, and it also has reference -to the revolving switch on the shaft of a magneto whereby the current is -distributed to the various cylinders in regular order. - -Fig. 57 shows a form of distributer which will illustrate the -construction. A is the shaft which is driven at one half the engine -speed. It is usually run by suitable gearing direct from the shaft of -the magneto. - -[Illustration: _Fig. 57. The Distributer._] - -Its outer end rests in a bearing plate B, of insulating material, which -plate serves as the disk to hold the contact plates, 1, 2, 3, 4, to -correspond with the four cylinders to which the current is to be -distributed. - -Wires 5, 6, 7, and 8, run to the respective spark plugs C from these -contact plates. The projecting end of the shaft A carries thereon a -contact finger D, which is designed to contact with the respective -plates, and an insulating ring E is interposed between the shaft and -finger so as to prevent short circuiting of the high tension current. - -On the side of the finger is a hub F, integral therewith, and a wiper -attached to a post bears against the hub so as to form continuous -contact. A wire leads from the post to one terminal of the secondary -coil. - -[Illustration: _Fig. 58. Circuiting with Distributer._] - -Circuiting With Distributer.--The diagram Fig. 58 shows the complete -connections of a system which comprises a magneto, induction coil, -condenser, and a distributer. The magneto A has on its armature shaft B -two revolving disks C, D, one of which must be insulated from the shaft, -and one end of the coil E of the armature is connected with one of these -disks, and the other end of the coil is attached to the other disk. - -Alongside of these disks is another disk F which has projecting points G -to engage with and make temporary contact with a spring finger which -actuates the interrupter I, this being a contact breaker which breaks -the primary current at the time a spark is required. - -One terminal of this interrupter is connected by a wire J with one end -of the primary winding K, of the induction coil, and the other end of -the primary has a wire L which runs to the disk C. - -The other terminal of the interrupter has a wire M leading to a -condenser N, and from the other side of the condenser is a wire O -leading to the wire J before described. The wiper of the other disk D -has a wire connection with the wire M. - -The distributer shaft P is so mounted that it may receive its motion -from the shaft of the magneto, and for this purpose the latter shaft has -a gear Q one half the diameter of the gear R on the distributer shaft. - -The distributer S has been described with sufficient clearness in a -preceding diagram, to show how the wires T lead therefrom and connect up -with the spark plugs U. One terminal of the secondary coil V is -connected by a wire W with the wiper X which contacts with the hub of -the distributer finger X´, and the other terminal of the primary is -grounded at Y, which represents the metal of the engine. - - - - -CHAPTER IX - -MECHANICAL DEVICES UTILIZED IN POWER - - -One of the most important things in enginery is the capacity to -determine the power developed. Although the method of ascertaining this -appears to be somewhat complicated, it is really simple, and will be -comprehended the more readily if it is constantly borne in mind that a -certain weight must be lifted a definite distance within a particular -time. - -The Unit of Time.--The unit of time is either the second, or the minute, -usually the latter, because it would be exceedingly difficult to make -the calculations, or rather to note the periods as short as a second, -and a very simple piece of mechanism to ascertain this, is to mount a -horizontal shaft A, Fig. 59, in bearings B, B, and affix a crank C at -one end. - -It will be assumed that the shaft is in anti-friction bearings so that -for the present we shall not take into account any loss by way of -friction. - -A cord, with one end attached to the shaft and the other fixed to a -weight D, the latter weighing, say 550 pounds, is adapted to be wound -on the shaft as it is turned by the crank. - -Knowing the length of the cord and the time required to wind it up, it -will be an easy matter to figure out the power exerted to lift the -weight, which means, the power developed in doing it. - -[Illustration: _Fig. 59. Illustrating the Unit of Time._] - -Suppose the cord is 100 feet long, and it requires one and a half -minutes to raise the weight the full limit of the cord. It is thus -raising 550 pounds 100 feet in 45 seconds. - -One horse power means that we must raise 550 pounds one foot in one -second of time, hence we have developed only 1/45th of one horse power. - -Instead of using the crank, this shaft may be attached to the engine -shaft so it will turn slowly. Then add sufficient weight so that the -engine will just lift it, and wind the cord on the shaft. - -You can then note the time, for, say, one minute, and when the weight is -lifted, make the following calculation: Weight lifted one hundred feet -in one minute of time was 825 pounds. Multiply 100 by 825, which equals -82,500. This represents _foot pounds_. - -[Illustration: Fig. 60. The Proney Brake.] - -As there are 33,000 foot pounds in a horse power, 82,500 divided by this -figure will show that 2-1/2 horse power were developed. - -The Proney Brake.--Such a device is difficult to handle, but it is -illustrated merely to show the simplicity of the calculation. As a -substitute for this mechanism, a device, called the _Proney brake_ has -been devised, which can be used without rewinding of a cord. This is -accomplished by frictional means to indicate the power, and by the use -of weights to determine the lift. - -The following is a brief description of its construction: The engine -shaft A, Fig. 60, which is giving out its power, and which we want to -test, has thereon a pulley B, which turns in the direction of the -arrow. Resting on the upper side of the pulley is a block C, which is -attached to a horizontal lever D by means of bolts E, these bolts -passing through the block C and lever D, and having their lower ends -attached to the terminals of a short sprocket chain F. - -Block segments G are placed between the chain and pulley B, and when the -bolts E are tightened the pulley is held by frictional contact between -the block C and the segments G. - -The free end of the lever has a limited vertical movement between the -stops H, and a swinging receptacle I, on this end of the lever, is -designed to receive weights J. - -The first thing to do is to get the dimensions of the pulley, its speed, -and length of the lever. By measurement, the diameter of the pulley is -six inches. To get the circumference multiply this by 3.1416. The -distance around, therefore, is a little over 18.84 inches. The speed of -the pulley being 225 times per minute, this figure, multiplied by 18.84, -gives the perimeter of the pulley 4239 inches. - -As we must have the figures in feet, dividing 4239 by 12, we have 353.25 -feet. - -The length of the lever from the center of the pulley to the suspension -point of the receptacle, is 4 feet, and this divided by the radius of -the pulley (which is 6 inches), gives the leverage. One half of six -inches, is three inches, or 1/4 of one foot, and 4 divided by this -number, is 1' 4", or 1-1/3 feet, which is the _leverage_. - -Now, let us suppose the weight J is 1200 pounds. This must be multiplied -by the leverage, 1-1/3 feet, which equals 1800, and this must be -multiplied by the feet of travel in the pulley, namely, 353.25, which is -equal to 635,850. This represents _foot pounds_. - -Now, following out the rule, as there are 33,000 foot pounds in a horse -power, the foregoing figure, 635,850, divided by 33,000, equals 19 horse -power within a fraction. - -Reversing Mechanism.--A thorough knowledge of the principles underlying -the various mechanical devices, and their construction, is a part of the -education belonging to motors. One of the important structures, although -it is very simple, when understood, requires some study to fully master. - -This has reference to reversing mechanism, which is, in substance a -controllable valve motion, whereby the direction of the valve is -regulated at will. - -All motions of this character throw the valve to a neutral point which -is intermediate the two extremes, and the approach to the neutral means -a gradual decrease in the travel of the valve until the reciprocating -motion ceases entirely at the neutral position. - -[Illustration: _Fig. 61. Double Eccentric Reversing Gear._] - -[Illustration: _Fig. 62. Reversing Gear, Neutral._] - -Double Eccentric Reversing Gear.--A well known form of gear is shown in -Fig. 61, in which the engine shaft A has two eccentrics B, C, the upper -eccentric B being connected with the upper end of a slotted segment D by -means of a stem E, and the other eccentric C is connected with the lower -end of the segment by the stem F. The eccentrics B, C, are mounted on -the shaft so they project in opposite directions. - -The slotted segment carries therewith the pin G of a valve rod H, and -the upper end of the segment has an eye I, to which eye is a rod J -operated by a lever. - -[Illustration: _Fig. 63. Reversing Gear, Reversed._] - -[Illustration: _Fig. 64. Single Eccentric Reversing Gear._] - -By this arrangement the link may be raised or lowered, and as the valve -rod pin has no vertical movement, either the connecting link E or F may -be brought into direct line with the valve rod H. - -Fig. 61 shows the first position, in which the valve rod H is in direct -line with the upper connecting rod E, actuated by the cam B. - -Fig. 62 shows the neutral position. Here the pin G serves as a fulcrum -for the rocking movement of the segment; whereas in Fig. 63 the valve -rod H is in line with the lower connecting rod F, so that the valve is -pushed to and fro by the eccentric C. - -[Illustration: _Fig. 65. Balanced Slide Valve._] - -It is more desirable, in many cases, to use a single eccentric on the -engine shaft, which can be done by pivoting the segment L, Fig. 64, to a -stationary support M, and connecting one end of the segment by a link N -with the single eccentric O. - -In this construction the valve rod P is shifted vertically by a rod Q, -operated from the reversing lever, thus providing a changeable motion -through one eccentric. - -Balanced Slide Valves.--In the chapter pertaining to the steam engine, -a simple form of slide valve was shown, and it was stated therein that -the pressure of the steam bearing on the valve would quickly grind it -down. To prevent this various types of balanced valves have been made, a -sample of which is shown in Fig. 64. - -The valve chest A has in its bottom two ports C, D, leading to the -opposite ends of the cylinder, and within is the sliding valve E, which -moves beneath an adjustable plate F connected with the top or cover G of -the valve chest. - -[Illustration: _Fig. 66. Valve Chest. Double Port Exhaust._] - -This is also modified, as shown in Fig. 66, in which case the slide -valve H bears against the cover I at two points, so that as there is -steam on the upper surface to a slightly greater area than on the lower -side, there is sufficient downward pressure to hold it firmly on its -seat, and at the same time not cause any undue grinding. This valve also -has double exhaust ports J, J. - -Balanced Throttle Valve.--Fig. 67 will give a fair idea of the -construction of throttle valves, the illustration showing its connection -with a simple type of governor. - -[Illustration: _Fig. 67. Balanced Throttle-Valve._] - -Engine Governors.--Probably the oldest and best known governor for -regulating the inlet of steam to an engine, is what is known as the Watt -design. This is shown in Fig. 68. - -The pedestal A which supports the mechanism, has an upwardly-projecting -stem B, to the upper end of which is a collar C, to which the -oppositely-projecting pendent arms D are hinged. These arms carry balls -E at their free ends. - -[Illustration: Fig. 68. Watt's Governor.] - -The lower part of the stem has thereon a sliding collar F, and links G, -with their lower ends hinged to the collar, have their upper ends -attached to the swinging arms D. The collar has an annular groove at its -lower end, to receive therein the forked end of one limb of a bell-crank -lever H, the other limb of this lever being connected up with the engine -throttle, by means of a link L. - -Centrifugal motion serves to throw out the balls, as indicated by the -dotted lines J, and this action raises the bell-crank lever, and opens -the throttle valve. - -Numerous types of governors have been constructed, some of which operate -by gravity, in connection with centrifugal action. Some are made with -the balls adapted to swing downwardly, and thrown back by the action of -springs. Others have the balls sliding on horizontally-disposed arms, -and thrown back by the action of springs; and gyroscopic governors are -also made which are very effective. - -[Illustration: _Fig. 69. The Original Injector._] - -Fly wheel governors are not uncommon, which are placed directly on the -engine shaft, or placed within the fly wheel itself, the latter being a -well known form for engines which move slowly. - -Injectors.--The Injector is one of the anomalies in mechanism. It -actually forces water into a boiler by the action of the steam itself, -against its own pressure. It is through the agency of condensation that -it is enabled to do this. - -The illustration, Fig. 69, which represents the original type of the -device, comprises a shell A, within which is a pair of conically formed -tubes, B, C, in line with each other, the small ends of the tubes being -pointed towards each other, and slightly separated. The large end of the -conical tube C, which points toward the pipe D, which leads to the water -space of the boiler, has therein a check valve E. - -The steam inlet pipe F, has a contracted nozzle G, to eject steam into -the large end of the conical tube B, and surrounding the nozzle F is a -chamber which has a pipe H leading out at one side, through which cold -water is drawn into the injector. - -Surrounding the conical pipes B, C, is a chamber I, which has a -discharge pipe J. The action of the device is very simple. When steam is -permitted to flow into the conical tube B, from the nozzle G, it passes -out through the drain port J, and this produces a partial vacuum to form -in the space surrounding the nozzle G. - -As a result water is drawn up through the pipe H, and meeting with the -steam condenses the latter, thereby causing a still greater vacuum, and -this vacuum finally becomes so great that, with the inrushing steam, -and the rapid movement through the conical tubes, past their separated -ends, a full discharge through the drain J is prevented. - -[Illustration: Fig. 70. Injector with Movable Combining Tube.] - -As it now has no other place to go the check valve E is unseated, and -the cold water is forced into the boiler through the pipe D, and this -action will continue as long as condensation takes place at the nozzle -G. - -Many improvements have been made on the original form, mostly in the -direction of adjusting the steam nozzle, and to provide the proper -proportion of flow between the steam and water, as this must be adjusted -to a nicety to be most effective. - -An example of a movable tube which closes the outlet to the overflow, -is shown in Fig. 70. The steam inlet tube A is at one end of the shell, -and the outlet tube B to the boiler, at the other end, and intermediate -the two is a tube C, with its open flaring end adapted to receive the -steam from the tube A. This tube is longitudinally-movable, so that the -controlling lever D may move it to and fro. - -A chamber E surrounds the nozzle A, and has a water inlet pipe F, while -the space G between the ends of the pipes B, C, has an outlet H, a -single check valve I being interposed. In operation the tube C may be -adjusted the proper distance from the end of the pipe B, and when the -current is once established through the injector, the pipe C may be -brought into contact with B, and thus entirely cut out the movement of -the water to the overflow. - -Feed Water Heater.--An apparatus of this kind is designed to take the -exhaust steam from the engine and condense it, and from the condenser it -is again returned to the boiler. The water thus used over again goes -into the boiler at a temperature of over 180 degrees, and thus utilizes -the heat that would otherwise be required to raise the temperature of -the water from the natural heat, say 70, up to that point. - -In Fig. 71 the illustration shows a typical heater, which comprises an -outer shell A, each end having a double head, the inner head B being -designed to receive the ends of a plurality of horizontally disposed -pipes, and the outer heads C, separated from the inner head so as to -provide chambers, one end having one, and the other head being provided -with two horizontal partitions D, so the water may be diverted back and -forth through the three sets of pipes within the shell. - -[Illustration: _Fig. 71. Feed Water Heater._] - -The three sets of pipes, E, F, and G, are so arranged that they carry -the water back and forth from one head to the other, and for this -purpose the water for cooling the steam enters the port H at one end, -passes through the upper set of pipes E to the other end, then back -through the same set of pipes on the other side of a partition, not -shown, and back and forth through the two lower sets of pipes F, G. - -The steam enters at the port I at the top of the shell, and passes down, -as it is condensed, being discharged at the outlet J. - - - - -CHAPTER X - -VALVES AND VALVE FITTINGS - - -In the use of steam, compressed gas, or any medium which must have a -controllable flow, valves are a necessary element; and the important -point is to know what is best adapted for the use which is required in -each case. - -For this reason one of the best guides is to fully understand the -construction of each. The following illustrations and descriptions will -give a good idea of the various types in use. - -[Illustration: _Fig. 72. Check Valve._] - -Check Valve.--Fig. 72 shows a longitudinal section of a check valve, -which is designed to prevent the water from returning or backing up -from the pressure side. The cylindrical body A is threaded at each end, -and has an inclined partition B therein which has a circular aperture. - -[Illustration: _Fig. 73. Gate Valve._] - -The upper side of the shell has an opening, adapted to be closed by a -cap C, large enough to insert the valve D, which is hinged to the upper -side of the partition. Water or gas is forced in through the valve in -the direction of the arrow, and the hinged valve is always in position -to close the opening in the partition. - -In case the valve should leak it may be readily ground by taking the -small plug E from the opening, and with a screw driver, turning the -valve, and thereby fit it snugly on its seat. - -[Illustration: _Fig. 74. Globe Valve._] - -Gate Valve.--The cylindrical shell A has its ends internally threaded, -and is provided, midway between its ends, with a partition wall B, -having a central aperture. The upper side of the shell has an opening to -receive the bonnet C, through which the valve stem D passes. This stem -carries at its lower end a gate E which rests against the partition B. - -The stem D is threaded to screw into the threaded bore of the gate. A -packing gland F surrounds the stem D. It will thus be seen that the -turning of the stem D draws the gate up or down, and thus effects an -opening, which provides a direct passage for the water through the valve -body. - -Globe Valve.--A globe valve has the advantage that the valve is forced -against its seat by the pressure of the wheel, differing from the gate -valve, that depends on the pressure of the fluid to keep it tight. - -The valve body A has therein a Z-shaped partition B, the intermediate, -horizontally-disposed limb of the partition being directly below the -opening through the body, which is designed to receive the bonnet C. - -The bonnet has a central vertical bore, the lower end of which is -threaded to receive the wheel spindle. The lower end of the spindle -carries the circular valve, which is seated in the opening of the -Z-shaped partition. - -The Corliss Valve.--The valve itself is of the rotary type, as shown in -Fig. 75, in which the port A goes to the cylinder, and B is the passage -for the steam from the boiler. The cylindrical valve body C has within -the aperture B a gate D, one edge of which rests against the abutment -through which the port A is formed, and this gate has within it the bar -E which is connected with the crank outside of the casing. - -The Corliss Valve-Operating Mechanism.--As the operation of the valves -in the Corliss type of engine is so radically different from the -ordinary reciprocation engine, a side view of the valve grouping and its -connecting mechanism are shown in Fig. 76. - -[Illustration: _Fig. 75. Corliss Valve._] - -The cylinder has an inlet valve A at each end, and an outlet valve B at -each end for the discharge of the steam. C is a valve rod from the -eccentric which operates the valves, and D a wrist plate, having an -oscillatory or rocking motion around its center E. The attachments F F, -of the steam rods, open the inlet ports A A, and G G, are the -attachments of exhaust rods which open and close the exhaust valves B B. -H H are catches which can be unhooked from the stems of the valves A by -the governor rods J J. - -The vertical links K, K are connected at their lower ends with the -pistons of dash pots, and have their upper ends attached to the valve -spindles, and act to close the valves A A when the catches H are -released by the governor rods J by means of the weights of the pistons -in the dash pots. - -[Illustration: _Fig. 76. Corliss Valve-operating Mechanism._] - -The dash pots L L act in such a manner as to cushion the descent of the -links K and thus prevent undue shock. M is a wrist plate pin by which -the valve rod C can be released from the wrist plate. - -The whole purpose of the mechanism is to provide a means for closing the -valves which are at the steam inlet ports, by a sudden action. The -exhaust valves, on the other hand, are not so tripped but are connected -directly with the wrist plate which drives all four of the valves. - -The wrist plate or spider has a rocking motion, being driven by an -eccentric rod from the engine-shaft. The mechanism thus described gives -a variable admission as the load varies, but a constant release of the -exhaust and a constant compression to act as a cushion. - -[Illustration: _Fig. 77. Angle Valve._] - -It gives a high initial pressure in the cylinder, and a sharp cut off, -hence it is found to be very efficient. - -Angle Valve.--One of the most useful is the angle valve, which is -designed to take the place of an angle bend or knee in the line of the -piping. The mechanism is the same as in the well known globe valve -construction, the bonnet A being on a line with one of the right-angled -limbs of the body. - -The pressure of the fluid should always be on the lower side of the -valve C, coming from the direction of the arrow B, for the reason that -should the steam pressure be constant on the other side, it would be -difficult to repack the gland D without cutting off the steam from the -pipe line. - -[Illustration: _Fig. 78. Rotary Valve._] - -[Illustration: _Fig. 79. Two-way Rotary._] - -Referring back to the illustration of the globe valve, it will be -noticed that the same thing, so far as it pertains to the direction of -the steam, applies in that construction, and a common mistake is to -permit the pressure of the steam to be exerted so that it is constantly -acting against the packing of the spindle. - -Rotary Valves.--Two forms of rotary valves are shown, one as illustrated -in Fig. 78, where the rotating part, or plug, A has one straight-way -opening B, which coincides with two oppositely-projecting ports C, D. - -The other form, Fig. 79, has an L-shaped opening E through the rotating -plug F, and the casing, in which the plug is mounted has three ports, -one, G, being the inlet, and the other two H, I, at right angles for the -discharge of the fluid. - -[Illustration: Fig. 80. Rotary Type.] - -[Illustration: _Fig. 81. Two-way Rotary Type._] - -Rotable Engine Valves.--So many different forms of the rotable valve -have been made, that it is impossible to give more than a type of each. -For engine purposes the plugs are usually rotated in unison with the -engine shaft, and a single delivery valve of this kind is shown in Fig. -80. - -This has three ports in the casing, namely the inlet port A, and two -outlet ports C, D. The plug has a curved cut out channel E, and this -extends around the plug a distance equal to nearly one-half of the -circumference, so that the steam will be diverted into, say, B, for a -period equal to one-quarter turn of the plug, and then into port C, for -the same length of time. - -Fig. 81 shows a valve which has a double action. The plug G has two -oppositely-disposed curved channels, H, I, and the casing has a single -inlet port J, and two oppositely-disposed outlet ports K, L. - -[Illustration: _Fig. 82. Butterfly Throttle._] - -[Illustration: _Fig. 83. Angle Throttle._] - -When the plug turns the port L serves to convey the live steam to the -engine, while the other port K at the same time acts as the exhaust, and -this condition is alternately reversed so that L acts as the discharge -port. - -Throttle Valves.--The throttle valves here illustrated are those used in -connection with gasoline engines. The best known is the _Butterfly_ -valve, shown in Fig. 82, and this is also used as a damper, for -regulating the draft in furnaces and stoves. - -This type is made in two forms, one in which the two wings of the valve -are made to swing up or down in unison, and the other, as illustrated, -where the disk A is in one piece, and turns with the spindle B to which -it is fixed. - -[Illustration: _Fig. 84. Slide Throttle._] - -[Illustration: _Fig. 85. Two-slide Throttle._] - -In Fig. 83 the wing C is curved, so that by swinging it around the -circle, the opening of the discharge pipe D is opened or closed. - -Another design of throttle is represented in Fig. 84. One side of the -pipe A has a lateral extension B, which is double, so as to receive -therein a sliding plate C, which is easily controllable from the -outside. - -Fig. 85 shows a form of double sliding plate, where the double lateral -extensions project out in opposite directions, as at D, D, and within -these extensions are sliding plates which are secured together in such a -way that as one is pushed in the other also moves in, and thus acts in -unison to close or to open the space between them. It is the most -perfect form of throttle valve, as it causes the gases to open directly -into the center of the outgoing pipe. - -Blow-off Valves.--The illustration shows a type of valve which is used -on steamboats and very largely on farm boilers throughout the country. -The pipe A from the boiler has cast therewith, or otherwise attached, a -collar B, which has a standard C projecting upwardly at one side, to the -upper end of which is hinged a horizontal lever D, which has a weight at -its other end. - -[Illustration: _Fig. 86. Blow-off Valve._] - -The upper end of the pipe has a conically-ground seat, to receive a -conical valve E, the stem of which is hinged, as at F, to the level. The -weight may be adjusted to the pressure desired before blowing out and -the only feature in this type of valve is the character of the valve -seat, which is liable, through rust, and other causes, to leak. - -Pop, or Safety Valve.--As it has been found more desirable and practical -to use a form of valve which is not liable to deterioration, and also to -so arrange it that it may be manually opened, the _Safety Pop_ valve was -devised. - -[Illustration: _Fig. 87. Safety Pop Valve._] - -This is shown in Fig. 87, in which the valve seat base A, which is -attached to the top of the boiler, has a cup-shaped outlet B, that is -screwed to it, and this carries a lever C, by means of which the valve -may be manually opened. - -A vertical shell D is attached to the cup-shaped portion, and this has a -removable cap E. The valve F is seated within a socket in the base, and -has a disk head, to receive the lower end of a coiled spring G. - -The spring is supported in position by a stem H which extends down from -the head, and an adjusting nut I serves to regulate the pressure desired -before the steam in the boiler can act. - - - - -CHAPTER XI - -CAMS AND ECCENTRICS - - -More or less confusion arises from the terms _cams_ and _eccentrics_. A -cam is a wheel which may be either regular in shape, like a -_heart-wheel_, or irregular, like a _wiper-wheel_. - -The object in all forms of cams is to change motion from a regular into -an irregular, or reversely, and the motion may be accelerated or -retarded at certain points, or inverted into an intermittent or -reciprocating movement, dependent on the shape of the cam. - -A cam may be in the shape of a slotted or grooved plate, like the needle -bar of a sewing machine, where a crank pin works in the slot, and this -transmits an irregular vertical movement to the needle. - -A cam may have its edge provided with teeth, which engage with the teeth -of the engaging wheel, and thus impart, not only an irregular motion but -also a turning movement, such forms being largely used to give a quickly -rising or falling motion. - -What are called _wiper-wheels_ are designed to give an abrupt motion and -such types are used in trip hammers, and to operate stamp mills. In -harvesters, printing presses, sewing machines, and mechanism of that -type, the cam is used in a variety of forms, some of them very ingenious -and complicated. - -[Illustration: _Fig. 88. Heart-shaped._] - -[Illustration: _Fig. 89. Elliptic._] - -[Illustration: Fig. 90. Double Elliptic.] - -Cams are also used for cutting machines, or in tracing apparatus where -it would be impossible to use ordinary mechanism. All such forms are -special, requiring care and study to make their movements co-relate with -the other parts of the mechanism that they are connected up with. - -Simple Cams.--Fig. 88 shows a form of the most simple character, used, -with some modifications, to a larger extent than any other. It is called -the _heart-shaped_ cam, and is the regular type. - -Fig. 89 is an elliptical cam, which is also regular. What is meant by -_regular_ is a form that is the same in each half portion of its -rotation. - -Fig. 90 is a double elliptic, which gives a regular movement double the -number of times of that produced by the preceding figure, and the -differences between the measurements across the major and minor axes may -vary, relatively, to any extent. - -[Illustration: _Fig. 91. Single Wiper._] - -[Illustration: _Fig. 92. Double Wiper._] - -[Illustration: _Fig. 93. Tilting Cam._] - -Wiper Wheels.--Wiper wheels are cams which give a quick motion to -mechanism, the most common form being the single wiper, as shown in Fig. -91. - -The double wiper cam, Fig. 92, has, in some mechanism, a pronounced -difference between the lengths of the two fingers which form the wipers. - -The form of cam shown in Fig. 93 is one much used in iron works for -setting in motion the tilt hammer. Only three fingers are shown, and by -enlarging the cam at least a dozen of these projecting points may be -employed. - -Cam Sectors.--Fig. 94 shows a type of cam which is designed for rock -shafts. The object of this form of cam is to impart a gradually -increasing motion to a shaft. Assuming that A is the driving shaft, and -B the driven shaft, the cam C, with its short end D, in contact with the -long end E of the sector F, causes the shaft B to travel at a more -accelerated speed as the other edges G, H, approach each other. - -[Illustration: _Fig. 94. Cam Sector._] - -[Illustration: _Fig. 95. Grooved Cam._] - -[Illustration: _Fig. 96. Reciprocating Motion._] - -Cylinder Cam.--Fig. 95 shows one form of cylinder A with a groove B in -it, which serves as a means for moving a bar C back and forth. The bar -has a projecting pin D, which travels in the groove. - -This form of movement may be modified in many ways, as for instance in -Fig. 96, where the drum E has a sinuous groove F to reciprocate a bar G -to and fro, the groove being either regular, so as to give a continuous -back and forth movement of the bar; or adapted to give an irregular -motion to the bar. - -[Illustration: _Fig. 97. Pivoted Follower for Cam._] - -Double Cam Motion.--Cams may also be so arranged that a single one will -produce motions in different directions successively, as illustrated in -Fig. 97. The horizontal bar A, hinged at B to the upper end of a link C, -has its free end resting on the cam D. - -The arm A has also a right-angled arm E extending downwardly, and is -kept in contact with the cam by means of a spring F. Connecting rods G, -H, may be hinged to the arm E and bar A, respectively, so as to give -motion to them in opposite directions as the cam revolves. - -Eccentrics.--An eccentric is one in which the cam or wheel itself is -circular in form, but is mounted on a shaft out of its true center. An -eccentric may be a cam, but a cam is not always eccentric in its shape. -The term is one in direct contrast with the word _eccentric_. - -[Illustration: _Fig. 98. Eccentric._] - -[Illustration: _Fig. 99. Eccentric Cam._] - -Fig. 98 shows the wheel, or the cam, which is regular in outline, that -is circular in form, but is mounted on the shaft out of its true center. -In this case it is properly called an eccentric cam but in enginery -parlance it is known as the eccentric, as represented in Fig. 99. - -Triangularly-Formed Eccentric.--Fig. 100 illustrates a form of cam which -has been used on engines. The yoke A being integral with the bar B, -gives a reciprocating motion to the latter, and the triangular form of -the cam C, which is mounted on the shaft D, makes a stop motion at each -half-revolution, then produces a quick motion, and a slight stop only, -at the half turn, and the return is then as sudden as the motion in the -other direction. - -[Illustration: Fig. 100. Triangularly-formed Eccentric.] - - - - -CHAPTER XII - -GEARS AND GEARING - - -For the purpose of showing how motion may be converted from a straight -line or from a circular movement into any other form or direction, and -how such change may be varied in speed, or made regular or irregular, -the following examples are given, which may be an aid in determining -other mechanical devices which can be specially arranged to do -particular work. - -While cams and eccentrics may be relied on to a certain extent, there -are numerous places where the motion must be made positive and -continued. This can be done only by using gearing in some form, or such -devices as require teeth to transmit the motion from one element to the -other. - -The following illustrations do not by any means show all the forms which -have been constructed and used in different machines, but they have been -selected as types merely, in order to give the suggestions for other -forms. - -Racks and Pinions.--The rack and pinion is the most universal piece of -mechanism for changing motion. Fig. 101 illustrates it in its most -simple form. When constructed in the manner shown in this figure it is -necessary that the shaft which carries the pinion shall have a rocking -motion, or the rack itself must reciprocate in order to impart a rocking -motion to the shaft. - -[Illustration: Fig. 101. Rack and Pinion.] - -[Illustration: Fig. 102. Rack Motion.] - -This is the case also in the device shown in Fig. 102, where two rack -bars are employed. A study of the cams and eccentrics will show that the -transference of motion is limited, the distances being generally very -small; so that the rack and pinions add considerably to the scope of the -movement. - -The Mangle Rack.--The device called the _mangle rack_ is resorted to -where a back and forth, or a reciprocating movement is to be imparted -to an element by a continuous rotary motion. - -[Illustration: Fig. 103. Plain Mangle Rack.] - -[Illustration: Fig. 104. Mangle Rack Motion.] - -[Illustration: Fig. 105. Alternate Circular Motion.] - -The plain mangle racks are shown in Figs. 103 and 104, the former of -which has teeth on the inside of the opposite parallel limbs, and the -latter, Fig. 104, having teeth not only on the parallel sides, but also -around the circular parts at the ends. - -This form of rack may be modified so that an alternate circular motion -will be produced during the movement of the rack in either direction. -Fig. 105 is such an instance. A pinion within such a rack will turn -first in one direction, and then in the next in the other direction, and -so on. - -If the rack is drawn back and forth the motion imparted to the pinion -will be such as to give a continuous rocking motion to the pinion. - -Controlling the Pinion.--Many devices have been resorted to for the -purpose of keeping the pinion in engagement with the teeth of the mangle -rack. One such method is shown in Fig. 106. - -[Illustration: Fig. 106. Controlling Pinion for Mangle Rack.] - -The rack A has at one side a plate B, within which is a groove C, to -receive the end of the shaft D, which carries the pinion E. As the -mangle rack moves to such a position that it reaches the end of the -teeth F on one limb, the groove C diverts the pinion over to the other -set of teeth G. - -All these mangle forms are substitutes for cranks, with the advantage -that the mangle gives a uniform motion to a bar, whereas the to and fro -motion of the crank is not the same at all points of its travel. - -Examine the diagram, Fig. 107, and note the movement of the pin A which -moves along the path B. The crank C in its turning movement around the -circle D, moves the pin A into the different positions 1, 2, 3, etc., -which correspond with the positions on the circle D. - -[Illustration: Fig. 107. Illustrating Crank-pin Movement.] - -The Dead Centers.--There is also another advantage which the rack -possesses. Where reciprocating motion is converted into circular motion, -as in the case of the ordinary steam engine, there are two points in the -travel of a crank where the thrust of the piston is not effective, and -that is at what is called the _dead centers_. - -In the diagram, Fig. 108, the ineffectiveness of the thrust is shown at -those points. - -Let A represent the piston pushing in the direction of the arrow B -against the crank C. When in this position the thrust is the most -effective, and through the arc running from D to E, and from H to G, -the cylinder does fully four-fifths of the work of the engine. - -[Illustration: _Fig. 108. The Dead Center._] - -While the crank is turning from G to D, or from I to J, and from K to L, -no work is done which is of any value as power. - -If, therefore, a mangle bar should be used instead of the crank it would -add greatly to the effectiveness of the steam used in the cylinder. - -[Illustration: _Fig. 109. Crank Motion Substitute._] - -Crank Motion Substitute.--In Fig. 109 the pinion A is mounted so that -its shaft is in a vertical slot B in a frame C. The mangle rack D, in -this case, has teeth on its outer edge, and is made in an elongated -form. The pinion shaft moves up and down the slot and thus guides the -pinion around the ends of the rack. - -[Illustration: Fig. 110. Mangle Wheel.] - -Mangle Wheels.--The form which is the most universal in its application -is what is called the _mangle wheel_. In Fig. 110 is shown a type -wherein the motion in both directions is uniform. - -Mangle wheels take their names from the ironing machines called -_mangles_. In apparatus of this kind the movement back and forth is a -slow one, and the particular form of wheels was made in order to -facilitate the operation of such machines. In some mangles the work -between the rollers is uniform back and forth. In others the work is -done in one direction only, requiring a quick return. - -In still other machines arrangements are made to provide for short -strokes, and for different speeds in the opposite directions, under -certain conditions, so that this requirement has called forth the -production of many forms of wheels, some of them very ingenious. - -[Illustration: _Fig. 111. Quick Return Motion._] - -The figure referred to has a wheel A, on one side of which is a -peculiarly-formed continuous slot B, somewhat heart-shaped in general -outline, one portion of the slot being concentric with the shaft C. - -Within the convolutions of the groove is a set of teeth D, concentric -with the shaft C. The pinion E, which meshes with the teeth D, has the -end of its shaft F resting in the groove B, and it is also guided within -a vertical slotted bar G. - -The pinion E, therefore, travels over the same teeth in both directions, -and gives a regular to and fro motion. - -Quick Return Motion.--In contradistinction to this is a wheel A, Fig. -111, which has a pair of curved parallel slots, with teeth surrounding -the slots. When the wheel turns nearly the entire revolution, with the -pinion in contact with the outer set of teeth, the movement transmitted -to the mangle wheel is a slow one. - -[Illustration: _Fig. 112. Accelerated Circular Motion._] - -When the pinion arrives at the turn in the groove and is carried around -so the inner teeth are in engagement with the pinion, a quick return is -imparted to the wheel. - -Accelerated Motion.--Aside from the rack and mangle type of movement, -are those which are strictly gears, one of them being a volute form, -shown in Fig. 112. This gear is a face plate A, which has teeth B on one -face, which are spirally-formed around the plate. These mesh with a -pinion C, carried on a horizontal shaft D. This shaft is feathered, as -shown at E, so that it will carry the gear along from end to end. - -[Illustration: _Fig. 113. Quick Return Gearing._] - -The gear has cheek-pieces F to guide it along the track of teeth. As the -teeth approach the center of the wheel A, the latter impart a motion to -the gear which is more than twice the speed that it receives at the -starting point, the speed being a gradually increasing one. - -Quick Return Gearing.--Another much more simple type of gearing, which -gives a slow forward speed and a quick return action, is illustrated in -Fig. 113. A is a gear with internal teeth through one half of its -circumference, and its hub B has teeth on its half which is opposite the -teeth of the rim. - -A pinion C on a shaft D is so journaled that during one half of the -rotation of the wheel A, it engages with the rim teeth, and during the -other half with the hub teeth. As the hub B and gear C are the same -diameter, one half turn of the pinion C will give a half turn to the -wheel A. - -[Illustration: _Fig. 114. Scroll Gearing._] - -As the rim teeth of the wheel A are three times the diameter of the -pinion C, the latter must turn once and a half around to make a half -revolution of the wheel A. - -Scroll Gearing.--This is a type of gearing whereby at the close of each -revolution the speed may be greater or less than at the beginning. It -comprises two similarly-constructed gears A, B, each with its perimeter -scroll-shaped, as shown. - -The diagram shows their positions at the beginning of the rotation, the -short radial limb of one gear being in line with the long limb of the -other gear, hence, when the gears rotate, their speeds relative to each -other change, being constantly accelerated in one or decreased in the -other. - - - - -CHAPTER XIII - -SPECIAL TYPES OF ENGINES - - -In describing various special types of motors, attention is first -directed to that class which depend on the development of heat in -various gases, and this also necessitates some explanation of ice-making -machinery, and the principles underlying refrigeration. - -It is not an anomaly to say that to make ice requires heat. Ice and -boiling water represent merely the opposites of a certain scale in the -condition of matter, just as we speak of light and darkness, up and -down, and like expressions. - -We are apt to think zero weather is very cold. Freezing weather is a -temperature of 32 degrees. At the poles 70 degrees below have been -recorded. In interstellar space,--that is, the region between the -planets, it is assumed that the temperature is about 513 degrees -Fahrenheit, below zero, called absolute zero. - -The highest heat which we are able to produce artificially, is about -10,000 degrees by means of the electric arc. We thus have a range of -over 10,500 degrees of heat, but it is well known that heat extends -over a much higher range. - -Assuming, however, that the figures given represent the limit, it will -be seen that the difference between ice and boiling water, namely, 180 -degrees, is a very small range compared with the temperatures referred -to. - -In order to effect this change power is necessary, and power requires a -motor of some kind. Hence it is, that to make a lower temperature, a -higher degree of heat is necessary, and in the transit between a high -and a low temperature, there is considerable loss in this respect, as in -every other phase of power mechanism, as has been pointed out in a -previous chapter. - -In order that we may clearly understand the phenomena of heat and cold, -let us take a receiver which holds a cubic foot of gas or liquid, and -exhaust all the air from it so the vacuum will be equivalent to the -atmospheric pressure, namely, 14.7 pounds per square inch. - -Alongside is a small vessel containing one cubic inch of water, which is -heated so that it is converted into steam, and is permitted to exhaust -into the receiver. When all the water is converted into steam and fills -the receiver we shall have the same pressure inside the receiver as on -the outside. - -It will be assumed, of course, that there has been no loss by -condensation, and that the cubic inch of water has been expanded 1700 -times by its conversion into steam. - -In a short time the steam will condense into water, and we now have, -again, a partial vacuum in the receiver, due, of course, to the change -in bulk from steam to water. Each time the liquid is heated it produces -a pressure, and the pressure indicates the presence of heat; and -whenever it cools a loss of pressure is indicated, and that represents -cold, or the opposite of heat. - -Now, putting these two things together, we get the starting point -necessary in the development of power. Let us carry the experiment a -step further. Liquids are not compressible. Gases are. The first step -then is to take a gas and compress it, which gives it an increase of -heat temperature, dependent on the pressure. - -If the same receiver is used, and say, two atmospheres are compressed -within it, so that it has two temperatures, and the exterior air cools -it down to the same temperature of the surrounding atmosphere, we are -ready to use the air within to continue the experiment. - -Let us convey this compressed gas through pipes, and thus permit it to -expand; in doing so the area within the pipes, which is very much -greater than that of the receiver, grows colder, due to the rarefied -gases within. Now bearing in mind the previous statement, that loss of -pressure indicates a lowering of temperature, we can see that first -expanding the gas, or air, by heat, and then allowing it to cool, or to -produce the heat by compressing it, and afterwards permitting it to -exhaust into a space which rarefies it, will make a lower temperature. - -It is this principle which is used in all refrigerating machines, -whereby the cool pipes extract the heat from the surrounding atmosphere, -or when making ice, from the water itself, and this temperature may be -lowered to any extent desired, dependent on the degree of rarefaction -produced. - -Let us now see how this applies to the generation of power in which we -are more particularly interested. - -All liquids do not evaporate at the same temperature as water. Some -require a great deal more than 212 degrees; others, like, for instance, -dioxide-of-carbon, will evaporate at 110 degrees, or about one half the -heat necessary to turn water into steam. - -On the other hand, all gases act alike so far as their heat absorption -is concerned, so that by using a material with a low evaporative unit, -less fuel will be required to get the same expansion, which means the -same power. - -To illustrate this, let us assume that we have equal quantities of -water, and of dioxide-of-carbon, and that is to be converted into a gas. -It will take just double the amount of fuel to convert the water into a -gaseous state. As both are now in the same condition, the law of heat -absorption is the same from this time on. - -The dioxide-of-carbon engine is one, therefore, which uses the vapor of -this material, which, after passing through the engine, is condensed and -pumped back to the boiler to be used over and over. - -In like manner, also, ether, which has a low point of vaporization, is -used in some engines, the principle being the same as the foregoing -type. - -Rotary Engines.--Many attempts have been made to produce a rotary type -of steam engine, and also to adapt it for use as an internal combustion -motor. - -The problem is a complicated one for the following reasons: First, it is -difficult to provide for cut-off and expansion. A rotating type, to be -efficient, must turn at a high rate of speed, and this makes the task a -more trying one. Second, the apparent impossibility of properly packing -the pistons. The result is a waste of steam, or the gas used to furnish -the power. Third, the difficulty in providing a suitable abutment so as -to confine the steam or gas, and make it operative against the piston. - -[Illustration: _Fig. 115. Simple Rotary Engine._] - -In Fig. 115 is shown a type of rotary which is a fair sample of the -characteristics of all motors of this form. It comprises an outer -cylindrical shell, or casing, A, having a bore through the ends, which -is above the true center of the shell, to receive a shaft B. - -This shaft carries a revolving drum C of such dimensions that it is in -contact with the shell at its upper side only, as shown at D, leaving a -channel E around the other portions of the drum. - -The steam inlet is at F, which is one-eighth of the distance around the -cylinder, and the exhaust is at G, the same distance from the point D, -on the other side. The inlet and the outlet pipes are, therefore, at the -contracted parts of the channel. - -The drum has a pair of radially-movable blades H H´, which may move -independently of each other, but usually they are connected together, -thus dispensing with the use of any springs to keep their ends in -contact with the shell. - -When steam enters the inlet F the pressure against the blade H drives -the drum to the right, and the drum and shell, by contacting at D, form -an abutment. Each charge of steam drives the drum a little over a half -revolution. - -A great deal of ingenuity has been exercised to arrange this abutment so -that the blades may pass and provide a steam space for a new supply of -steam. In certain types a revolving abutment is formed, as shown, for -instance, in Fig. 116. - -The shell A, in this case, has two oppositely-disposed inlet and outlet -ports, B, C, respectively, and between each set of ports is a revolving -gate, formed of four wings D, mounted on a shaft E, in a housing -outside of the circular path F, between the drum G and shell A. - -The drum G is mounted on a shaft H which is centrally within the shell, -and it has two oppositely-projecting rigid blades I. When steam enters -either of the supply ports B, the drum is rotated, and when the blades -reach the revolving gates, the latter are turned by the blades, or, they -may be actuated by mechanism connected up with the driving shaft. - -[Illustration: _Fig. 116. Double-feed Rotary Engine._] - -Caloric Engine.--This is an engine which is dependent on its action upon -the elastic force of air which is expanded by heat. The cylinder of -such a motor has means for heating it, and thus expanding the air, and a -compressor is usually employed which is operated by the engine itself, -to force compressed air into the cylinder. - -It is not an economical engine to work, but it is frequently used in -mines, in which case the compressor is located at the surface, and the -engine operated within the mine, thus serving a double purpose, that of -supplying power, and also furnishing the interior with fresh air. - -All engines of this character must run at a slow speed, for the reason -that air does not absorb heat rapidly, and sufficient time must be given -to heat up and expand the air, so as to make it effective. - -Adhesion Engine.--A curious exhibition of the action of a gas against a -solid, is shown in what is called an _Adhesion Engine_. Fig. 117 shows -its construction. A plurality of disks A are mounted on a shaft B, these -disks being slightly separated from each other. - -The steam discharge pipe C is flattened at its emission end, as shown at -D, so the steam will contact with all the disks. The steam merely -contacts with the sides of the disks, the movement of the steam being -substantially on the plane of the disks themselves, and the action sets -up a rapid rotation, and develops a wonderful amount of power. - -[Illustration: _Fig. 117. Adhesion Motor._] - -It will be understood that the disks are enclosed by a suitable casing, -so that the steam is carried around and discharged at a point about -three quarters of the distance in the circumference. - -This motor is given to illustrate a phase of the subject in the -application of a motor fluid, like steam, or heated gases, that shows -great possibilities. It also points out a third direction in which an -expansive fluid may be used. - -Thus the two well-known methods, namely, _pressure_, and _impact_ -forces, may be supplemented by the principle of _adhesion_, in which the -expansive force of a gas, passing alongside of and in contact with a -plain surface, may drag along the surface in its train. - -Such an exhibition of force has an analogy in nature by what is known as -capillary attraction, which shows _adhesion_. For instance, sap flowing -up the pores of trees, or water moving along the fibers of blotting -paper, illustrates movement of liquids when brought into contact with -solids. - - - - -CHAPTER XIV - -ENGINERY IN THE DEVELOPMENT OF THE HUMAN RACE - - -The energy of a nation may be expressed by its horse power. It is not -numbers, or intellect, or character, or beliefs that indicate the -progress of a people in a material sense. - -It is curious how closely related enginery is with the advancement of a -people. Nothing can be more striking to illustrate this than railroads -as a feature of development in any country. - -Power in Transportation.--Without the construction and maintenance of -mechanical power, railroads would be impossible. To be able to quickly -and cheaply move from place to place, is the most important factor in -human life. The ability of people to interchange commodities, and to -associate with others who are not in their own intimate community, are -the greatest civilizing agencies in the world. - -Power vs. Education and the Arts.--Education, the cultivation of the -fine arts, and the desire for luxuries, without the capacity for quickly -interchanging commodities and to intermingle with each other, are -ineffectual to advance the interests of any nation, or to maintain its -prosperity. - -Lack of Power in the Ancient World.--The Greeks and the Romans had a -civilization which is a wonder even to the people of our day. They had -the arts and architecture which are now regarded as superb and -incomparable. They had schools of philosophy and academies of learning; -their sculpture excites the admiration of the world; and they laid the -foundation theories of government from which we have obtained the basis -of our laws. - -The Early Days of the Republic.--When our forefathers established the -Republic there were many misgivings as to the wisdom of including within -its scope such a large area as the entire Atlantic seacoast. From Maine -to Florida the distance is 1250 miles; and from New York to the -Mississippi 900 miles, comprising an area of 1,200,000 square miles. - -How could such an immense country ever hold itself together? It was an -area nearly as large as that controlled by Rome when at the height of -her power. If it was impossible for the force of Roman arms to hold such -a region within its control, how much more difficult it would be for the -Colonies to expect cohesion among their scattered peoples. - -Lack of Cohesiveness in a Country Without Power.--Those arguments were -based on the knowledge that every country in ancient times broke apart -because there was no unity of interest established, and because the -different parts of the same empire did not become acquainted or -associated with each other. - -The Railroad as a Factor in Civilization.--The introduction of -railroads, by virtue of motive power, changed the whole philosophy of -history in this respect. Even in our own country an example of the value -of railroads was shown in the binding effect which they produced between -the East and the West prior to the Civil War. - -All railroads, before that period, ran east and west. Few extended north -and south. It is popularly assumed that the antagonism between the North -and the South grew out of the question of slavery. This is, no doubt, -largely so, as an immediate cause, but it was the direct cause which -prevented the building of railroads between the two sections. - -It simply reënforces the argument that the motor, the great power of -enginery, was not brought into play to unite people who were -antagonistic, and who could not, due to imperfect communication, -understand each other. - -To-day the United States contains an area nearly as great as the whole -of Europe, including Russia, with their twenty, or more, different -governments. Here we have a united country, with similar laws, habits, -customs and religions throughout. In many of those foreign countries the -people of adjoining provinces are totally unlike in their -characteristics. - -It has been shown that wherever this is the case it is due to lack of -quick and cheap intercommunication. - -The Wonderful Effects of Power.--This remarkable similarity in the -conditions of the people throughout the United States is due to the -railroads, that great personification of power, notwithstanding the -diverse customs and habits of the people which daily come to our shores -and spread out over our vast country. - -It has unified the people. It has made San Francisco nearer to New York -than Berlin was to Paris in the time of Napoleon. The people in Maine -and Texas are neighbors. The results have been so far reaching that it -has given stability to the government greater than any other force. - -But there is another lesson just as wonderful to contemplate. England -has an area of only about 58,000 square miles, about the same size as -either Florida, Illinois, or Wisconsin. - -England as a User of Power.--The enginery within her borders is greater -than the combined energy of all the people on the globe. Through the -wonderful force thus set in motion by her remarkable industries she has -become the great manufacturing empire of the world, and has called into -existence a carrying fleet of vessels, also controlled by motors, so -stupendous as to be beyond belief. - -We may well contemplate the great changes which have been brought about -by the fact that man has developed and is using power in every line of -work which engages his activities. - -The Automobile.--He does not, in progressive countries, depend on the -muscle of the man, or on the sinews of animals. These are too weak and -too slow for his needs. Look at the changes brought about by the -automobile industry within the past ten years. What will the next -century bring forth? - -Artificial power, if we may so term it, is a late development. It is -very young when compared with the history of man. - -High Character of Motor Study.--The study of motors requires intellect -of a high order. It is a theme which is not only interesting and -attractive to the boy, but the mastery of the subject in only one of -its many details, opens up a field of profit and emoluments. - -The Unlimited Field of Power.--It is a field which is ever broadening. -The student need not fear that competition will be too great, or the -opportunities too limited, and if these pages will succeed, in only a -small measure, in teaching the fundamental ideas, we shall be repaid for -the efforts in bringing together the facts presented. - - - - -CHAPTER XV - -THE ENERGY OF THE SUN, AND HOW HEAT IS MEASURED - - -In the first chapter we tried to give a clear view of the prime factors -necessary to develop motion. The boy must thoroughly understand the -principles involved, before his mind can fully grasp the ideas essential -in the undertaking. - -While the steam engine has been the prime motor for moving machinery, it -is far from being efficient, owing to the loss of two-thirds of the -energy of the fuel in the various steps from the coal pile to the -turning machinery. - -_First_, the fuel is imperfectly consumed, the amount of air admitted to -the burning mass being inadequate to produce perfect combustion. - -_Second_, the mechanical device, known as the boiler, is not so -constructed that the water is able to completely absorb the heat of the -fuel. - -_Third_, the engine is not able to continuously utilize the expansive -force of the steam at every point in the revolution of the crankshaft. - -_Fourth_, radiation, the dissipation of heat, and condensation, are -always at work, and thus detract from the efficiency of the engine. - -The gasoline motor, the next prime motor of importance, is still less -efficient in point of fuel economy, since less than one-third of the -fuel is actually represented in the mechanism which it turns. - -The production of energy, in both cases, involves the construction of a -multiplicity of devices and accessories, many of them difficult to make -and hard to understand. - -To produce power for commercial purposes, at least two things are -absolutely essential. First, there must be uniformity in the character -of the power produced; and, second, it must be available everywhere. - -Water is the cheapest prime power, but its use is limited to streams or -moving bodies of water. If derived from the air currents no dependence -can be placed on the regularity of the energy. - -Heat is the only universal power on the globe. The sun is the great -source of energy. Each year it expends in heat a sufficient force to -consume over sixty lumps of coal, each equal to the weight of the earth. - -Of that vast amount the earth receives only a small part, but the -portion which does come to it is equal to about one horse power acting -continuously over every thirty square feet of the surface of our globe. - -The great problem, in the minds of engineers, from the time the steam -engine became a factor, was to find some means whereby that energy might -be utilized, instead of getting it by way of burning a fuel. - -One of the first methods proposed was to use a lens or a series of -mirrors, by means of which the rays might be focused on some object, or -materials, and thus produce the heat necessary for expansion, without -the use of fuel. - -Wonderful results have been produced by this method; but here, again, -man meets with a great obstacle. The heat of the sun does not reach us -uniformly in its intensity; clouds intervene and cut off the rays; the -seasons modify the temperature; and the rotation of the globe constantly -changes the direction of the beams which fall upon the lens. - -The second method consists in using boxes covered with glass, the -interior being blackened to absorb the heat, and by that means transmit -the energy to water, or other substances adapted to produce the -expansive force. - -Devices of this character are so effective that temperatures much above -the boiling point of water have been obtained. The system is, however, -subject to the same drawbacks that are urged against the lens, namely, -that the heat is irregular, and open to great variations. - -These defects, in time, may be overcome, in conserving the force, by -using storage batteries, but to do so means the change from one form of -energy to another, and every change means loss in power. - -The great problem of the day is this one of the conversion of heat into -work. It is being done daily, but the boy should understand that the -_direct conversion_ is what is required. For instance, to convert the -energy, which is in coal, into the light of an electric lamp, requires -at least five transformations in the form of power, which may be -designated as follows: - -1. The burning of the coal. - -2. The conversion of the heat thus produced into steam. - -3. The pressure of the steam into a continuous circular motion in the -steam engine. - -4. The circular motion of the steam engine into an electric current by -means of a dynamo. - -5. The change from the current form of energy to the production of an -incandescent light in the lamp itself, by the resistance which the -carbon film offers to the passage of the current. Should an inventor -succeed in eliminating only one of the foregoing steps, he would be -hailed as a genius, and millions would not be sufficient to compensate -the fortunate one who should be able to dispense with three of the -steps set forth. - -The Measurement of Heat.--To measure heat means something more than -simply to take the temperature. As heat is work, or energy, there must -be a means whereby that energy can be expressed. - -It has been said that the basis of all true science consists in correct -definitions. The terms used, therefore, must be uniform, and should be -used to express certain definite things. When those are understood then -it is an easy matter for the student to grope his way along, as he meets -the different obstacles, for he will know how to recognize them. - -Before specifically explaining the measurement it might be well to -understand some of the terms used in connection with heat. The original -theory of heat was, that it was composed of certain material, although -that matter was supposed to be subtle, imponderable and pervading -everything. - -This imponderable substance was called _Caloric_. It was supposed that -these particles mutually attracted and repelled each other, and were -also attracted and repelled by other bodies, so that they contracted and -expanded. - -The phenomenon of heat was thus accounted for by the explanation that -the expansion and contraction made the heat. This was known as the -_Material Theory of Heat_. - -But that phase of the explanation has now been abandoned, in favor of -what is known as the _dynamical_, or _mechanical_ theory, which is -regarded merely as a _mode_ of _motion_, or a sort of vibration, wherein -the particles move among each other, with greater or less rapidity or in -some particular manner. - -Thus, the movements of the atoms may be accelerated, or caused to act in -a certain way, by friction, by percussion, by compression, or by -combustion. Heat is the universal result of either of those physical -movements. - -Notwithstanding that the material theory of heat is now abandoned, -scientists have retained, as the basis of all heat measurements, the -name which was given to the imponderable substance, namely, _Caloric_. - -It is generally written _Calorie_, in the text books. A calorie has -reference to the quantity of heat which will raise the temperature of -one kilogram of water, one degree Centigrade. - -As one kilogram is equal to about two pounds, three and a quarter -ounces, and one degree Centigrade is the same as one and two-thirds -degrees Fahrenheit, it would be more clearly expressed by stating that a -caloric is the quantity of heat required to raise the temperature of -one and one-fifth pound of water one degree Fahrenheit. - -This is known as the scientific unit of the thermal or heat value of a -caloric. But the engineering unit is what is called the British Thermal -Unit, and designated in all books as B. T. U. - -This is calculated by the amount of heat which is necessary to raise a -kilogram of water one degree Fahrenheit. According to Berthelot, the -relative value of calorics and B. T. U. are as follows: - -HEATS OF COMBUSTION - - --------------------------------------------------- - _Substance._ _Calories._ _B. T. U._ - --------------------------------------------------- - Hydrogen 34,500 62,100 - Carbon to carbon dioxide 8,137 14,647 - Carbon to carbon monoxide 2,489 4,480 - Carbon monoxide 2,435 4,383 - Methane 13,343 24,017 - Ethylene 12,182 21,898 - Cellulose 4,200 7,560 - Acetylene 12,142 21,856 - Peat 5,940 10,692 - Naphthalene 9,690 10,842 - Sulphur 2,500 4,500 - -When it is understood that heat is transmitted in three different ways, -the value of a measuring instrument, or a unit, will become apparent. - -Thus, heat may be transmitted either by _conduction_, _convection_, or -_radiation_. - -_Conduction_ is the method whereby heat is transmitted from one particle -to another particle, or from one end of a rod, or other material to the -other end. Some materials will conduct the heat much quicker than -others, but if we have a standard, such as the calorie, then the amount -of heat transmitted and also the amount lost on the way may be measured. - -_Convection_ applies to the transmission of heat through liquids and -gases. If heat is applied to the top or surface of a liquid, the lower -part will not be affected by it. If the heat is applied below, then a -movement of the gas or liquid begins to take place, the heated part -moving to the top, and the cooler portions going down and thus setting -up what are called _convection currents_. - -_Radiation_ has reference to the transference of heat from one body to -another, either through a vacuum, the air, or even through a solid. - -By means of the foregoing table, which gives the heats developed by the -principal fuels, it is a comparatively easy matter to determine the -calorific value of fuels, which is ascertained by making an analysis of -the fuel. - -The elements are then taken together, and the table used to calculate -the value. Suppose, for instance, that the analysis shows that the fuel -has seventy-five per cent. of carbon and twenty-five per cent. of -hydrogen. It is obvious that if we take seventy-five per cent. of 8,137 -(which is the index for carbon), and twenty-five per cent. of 43,500 -(the index of hydrogen), and adding the two together, the result, -14,727, would represent the calorific value of the fuel. - - - - -GLOSSARY OF WORDS - -USED IN TEXT OF THIS VOLUME - - - =Absolute.= Independent; free from all limitations. - - =Amplitude.= Greatness of extent; the state or quality - of being sufficient. - - =Absorbent.= A material which will take up a liquid. - - =Absorbing.= Taking up, or taking in. - - =Absorption.= The act or process of taking up or fully - occupying. - - =Abutment.= A wall; a stop. - - =Accuracy.= Correctness; positiveness. - - =Accession.= Added to; addition, or increase. - - =Accelerate.= Quickened; hurried. - - =Accessible.= Available; capable of being reached. - - =Accelerated.= A quickening, as of process or action. - - =Actuating.= Moved or incited by some motive. - - =Advance Spark.= The term applied to the movement of - the mechanism in an internal combustion - engine, which will cause the electric - spark to act before the crank has - passed the dead center. - - =Aeration.= To add air; to impregnate with oxygen. - - =Alkali.= In chemistry it is known as a compound of - hydrogen and oxygen, with certain - chemicals. Anything which will - neutralize an acid. - - =Allusion.= Referring to; noticed. - - =Anomaly.= A deviation from an ordinary rule; irregular. - - =Adhesion.= To cling to; to stick together. - - =Adjustment.= To arrange in proper order; to set into - working condition. - - =Alternating A current which goes back and - current.= forth in opposite directions; unlike a - direct current which flows continuously - in one direction. - - =Ampere.= The unit of current; the term in which - strength of current is measured. An - ampere is an electromotive force of one - volt through a resistance of one ohm. - - =Amplitude.= The state or quality of being broad, or full. - - =Analysis.= The separation into its primitive or - original parts. - - =Annular.= Pertaining to or formed like a ring. - - =Armature.= The part of a dynamo or motor which - revolves, and on which the wire coils - are wound. - - =Assuming.= Taking on; considered to be correct or - otherwise. - - =Asphaltum.= A bituminous composition used for - pavements, properly made from natural - bitumen, or from asphalt rock. - - =Atmospheric.= Referring to; noticed. - - =Available.= Capable of being employed or used. - - - =Bearings.= The part in mechanism in which journals or - spindles rest and turn. - - =Bifurcated.= In two parts; branching, like a fork. - - =Blow-off valve.= A valve so arranged that at certain - pressures the valve will automatically - open and allow the steam to escape from - the boiler. - - =Bombard.= An assault; an attack by shot or shell. - - =Bonnet.= The cap of a valve, which is so arranged - that while it permits the valve stem to - turn, will also prevent leakage. - - =Butterfly-valve.= A form of valve which is usually flat, - and adapted to open out, or turn - within the throat or pipe. - - - =Caloric.= Pertaining to heat. - - =Cam.= A rotating wheel, or piece, either regular or - irregular, non-circular, or eccentric. - - =Carbon.= A material like coke, ground or crushed. It - required high heat to burn it, and it - is used for the burning material in - electric arc lamps. - - =Carbureter.= The device used to mix air and gaseous - fuel in an internal combustion engine. - - =Carbonized.= Put into a charred form; coke is carbonized - coal; charcoal is carbonized wood. - - =Carbureted.= Air or gas to which has been added the - gaseous product of petroleum, or some - distillate. - - =Centripetal.= That which draws inwardly, or to the - center, like the gravitational action - of the earth. - - =Centrifugal.= That which throws outwardly; the - opposite of centripetal. - - =Check valve.= A form of valve which will permit - liquids to freely flow in one - direction, but which will open - automatically, so as to allow the - liquid to flow in the opposite - direction. - - =Chemical.= Pertaining to the composition of matter; - or relating to chemistry. - - =Chambered.= Having compartments, or divided up into - recesses. - - =Circumference.= Around the outside. - - =Circularly.= Around; about the circumference. - - =Circulation.= The movement of water to and fro - through conduits. - - =Clearance.= The space at the head of a cylinder - within which the steam or gases are - compressed by the piston. - - =Classification.= To put in order in a systematic way. - - =Coincide.= To correspond with identity of parts. - - =Cohesion.= To stick together. The attraction of - material substances of the same kind - for each other. - - =Coöperate.= To work together harmoniously. - - =Compounding.= Composed of or produced by the union of - two or more parts, or elements. - - =Complicated.= Very much involved; not simple. - - =Commutator.= The revolving part on the armature of a - dynamo or motor, which is divided up - into a multiplicity of insulated - plates, which are connected with the - coils of the wire around the armature. - - =Combustion.= Burning; the action of the unity of - oxygen with any substance, which causes - it to be destroyed or changed. - - =Commodity.= Any product, or kind of goods. - - =Concaved.= Hollowed. - - =Condensation.= The change from a gaseous to a liquid - or solid state. - - =Condenser.= An apparatus which converts a gas into a - liquid. - - =Concentric.= A line which at any point is at the same - distance from a common center. - - =Conductor.= A substance which will convey either heat - or electricity from one end to the - other. - - =Conical.= In the form of a cone. - - =Conically.= In the form of a cone. - - =Conduit.= A trough, tube, or other contrivance, which - will convey liquids or gases from place - to place. - - =Conduction.= The capacity to transmit from one point - to another. - - =Connecting Rod.= That part of mechanism which - connects the piston rod with the crank. - - =Conserve.= To take care of; to use judiciously. - - =Constant.= Being the same thing at all times; not - varying. - - =Contrivance.= Any mechanism, or device which will - serve a certain purpose. - - =Contra- That which is opposite to, - distinction.= comparatively; taken in conjunction - with for the purpose of comparison. - - =Cornish.= A form of boiler which has the fire tubes - within the water space. - - =Contact Breaker.= A device which has the current - normally in circuit, and is so arranged - that the circuit is broken at certain - intervals, and again immediately - reëstablished. - - =Co-relate.= Belonging to; having reference to the - same order. - - =Conventional.= The regular manner or method. - - =Contact Maker.= A device for making contacts in an - electric circuit at regular intervals. - - =Convolution.= The turns or twists taken. The changes - or movement or the peculiar flow of a - liquid. - - =Control.= Handling with regularity; The act of - guiding. - - =Contracted.= Made smaller. - - =Contingency.= An event; under certain conditions. - - =Counteract.= To antagonize; to so act as to go - against. - - =Converting.= Changing; to put in an opposite condition. - - =Cylindrical.= In the form of a cylinder; - barrel-shaped. - - =Cyclopedia.= A work which gives, in alphabetical order, - the explanations of terms and subjects. - - =Cycle.= A period extending over a certain time; a - certain order of events. - - - =Dead Center.= That point in the turn of a crank where - the piston has no effective pull in - either direction. - - =Deënergize.= To take power away from. - - =Deflecting.= To glance off; to change the regular or - orderly course. - - =Demagnetized.= To take magnetism away from. - - =Deterioration.= To take away from; to grow smaller; - to lessen; to depreciate in quality. - - =Deviate.= To avoid; to get around; not going or doing - in the regular way. - - =Diagram.= A mechanical plan or outline, as - distinguished from a perspective drawing. - - =Diametrically.= Across or through the object; through - the center. - - =Dioxide.= An oxide containing two atoms of oxygen to - the molecule. - - =Direct current.= An electric current which flows - continuously in one direction. - - =Dissipated.= Changed, or entirely dispensed with; - usually applied to a condition where - materials or substances are scattered. - - =Distributer.= A piece of mechanism in an electric - circuit, which switches the current - from one part to the other. - - =Dissect.= To take apart. - - =Dominating.= Overpowering; having greatest power. - - =Diverse.= Different; unlike. - - =Dry Cell.= A battery in which the electrolyte is not - in a fluid state. - - =Duct.= Either an open trough or conduit, or a closed - path for the movement of gases or liquids. - - =Dynamo.= A mechanical device for the purpose of - generating electricity. - - - =Eccentric.= A wheel having its perimeter so formed - that the center is not in the exact - middle portion. - - =Economy.= Prudence; carefulness; not disposed to be - excessive. - - =Efficiency.= Well adapted for the situation; - mechanism which will do the work - perfectly, or cheaply. - - =Effectiveness.= Well done; to the best advantage. - - =Ejecting.= Throwing out; sending forth. - - =Elastic.= That quality of material which tends to - cause it to return to its original - shape when distorted. - - =Elementary.= Primitive; the first; in the simplest - state. - - =Electric arc.= A term applied to the current which - leaps across the slightly separated - ends of an electric conductor. - - =Electricity.= An agent, incapable of being seen, but - which produces great energy. - - =Electrolyte.= The agent, or material in a battery, - usually a liquid, which the current - passes through in going from one - electrode to the other. - - =Elliptical.= A form which might be expressed by the - outline shape of an egg, measured from - end to end. - - =Emolument.= Pay; remuneration; the amount received - for employment of any kind. - - =Emission.= To send out from; a sending or putting out. - - =Energy.= Force; power. - - =Essential.= The main thing; the important element. - - =Evaporate.= To convert into vapor, usually by heat. - - =Exhaust.= The discharge part of an engine, or other - apparatus. - - =Excessive.= Too much; more than is required. - - =Expansion.= Enlarged; the occupying of a greater space. - - =Explicit.= Particularly definite; carefully explained - and understood. - - =External.= Outside; the outer surface. - - - =Facilitating.= Helping; aiding in anything. - - =Factor.= An element in a problem. - - =Fahrenheit.= One of the standards of heat - measurement. A thermometer scale, in - which the freezing point of water is - 32, and the boiling temperature is 212. - - =Fascinating.= Attractiveness; capacity to allure. - - =Feathered.= Applied to the shape of an article, or to - a rib on the side of a shaft, which is - designed to engage with a groove. - - =Fertilizer.= Material for enriching soil and - facilitating the growth of vegetables. - - =Field.= A term applied to the windings and the pole - pieces of a dynamo or motor, which - magnetically influence the armature. - - =Focal.= The point; the place to which all the - elements or forces tend. - - =Foot pounds.= The unit of mechanical work, being the - work done in moving one pound through - a distance of one foot. - - =Four-cycle.= A gasoline engine, in which the ignition - of the compressed hydro-carbon gases - takes place every other revolution. - - =Formation.= The arrangement of any mechanism, or a - series of elements. - - =Formula.= The recipe for the doing of a certain - thing; a direction. - - =Friction.= A retarding motion; the prevention of a - free movement. - - =Function.= The qualities belonging to an article, - machine or thing; that which a person - is capable of performing. - - =Fundamental.= The basis; the groundwork of a thing. - - - =Gaseous.= Of the nature of a gas. - - =Gearing.= Usually applied to two or more sets of - toothed wheels which coöperate with - each other. - - =Generating.= Producing; manufacturing; bringing out of. - - =Globules.= The small particles of liquids; or the - molecules comprising fluids. - - =Gravitation.= The force of the earth which causes all - things to move toward it; the - attraction of mass for mass. - - - =Heart Wheel.= A wheel having the outline of a heart. - - =Helical.= A spirally-wound form. - - =High Tension.= A term applied to a current of - electricity, which has a very high - voltage, but low amperage. - - =Horizontal.= Level, like the surface of water; at - right angles to a line which points to - the center of the earth. - - =Horse Power.= The unit of the rate of work, equal to - 33,000 pounds lifted one foot in one minute. - - =Hydro-carbon.= A gas made from the vaporization of - crude petroleum or of its distillates. - - =Hydrogen.= One of the original elements. The lightest - of all gases. - - - =Ignite.= To set on fire. - - =Ignition.= The term applied to the firing of a charge - of gas in a gas or gasoline engine. - - =Impact.= A blow; a striking force. - - =Impregnated.= To instill; to add to. - - =Impulse.= A natural tendency to do a certain thing; - determination to act in a certain way - through some influence. - - =Impinge.= To strike against; usually to contact with - at an angle. - - =Incomparable.= Too good or great to measure. - - =Inclined.= Not level; leaning; not horizontal. - - =Induction.= The peculiar capacity of an electric - current to pass from one conductor to - another through the air. - - =Indication.= That which shows; to point out. - - =Injector.= A device whereby the pressure of the steam - in a boiler will force water into the - boiler. - - =Initially.= At first; the original act. - - =Injection.= To put into; to eject from an apparatus, - into some other element. - - =Insulated.= So covered as to prevent loss of current - by contact with outside substances or - materials. - - =Intimate.= Close to; on good terms with. - - =Integral.= A complete whole; containing all the parts. - - =Instinct.= Knowledge within; something which - influences conduct or action. - - =Interstellar.= The space beyond the earth; that portion - of the heavens occupied by the stars. - - =Internal.= Within; that portion of mechanism which is - inside. - - =Interposing.= To step into; to place between, or in - the midst of. - - =Intensity.= Fierce; strong; above the ordinary. - - =Interrupted.= To stop; to take advantage of. - - =Interstices.= The spaces in between. - - =Instantaneous.= Immediately; at once; without waiting. - - =Intricate.= Difficult; not easy. - - =Inquisitive.= The desire to inquire into. - - - =Jacketing.= To coat or cover on the outside. - - =Jump Spark.= One of the methods of igniting - hydro-carbon gases. A current of - sufficiently high voltage is used to - cause the current to jump across the - space between the separated ends of a - conductor. - - - =Kinetic.= Consisting in or depending on motion. - - - =Latent.= That which is within itself. - - =Lateral.= Branching out from the sides; usually - applied as the meaning for the - direction which is at right angles to a - fore and aft direction. - - =Lines of force.= Applied to electricity, air, water, - or any moving element, which has a well - directed movement in a definite - direction. - - =Low Tension.= In methods for igniting hydro-carbon charges, - any circuiting which has a low voltage. - - =Lubrication.= The oiling of mechanical parts to - reduce friction. - - - =Mangle.= A machine for smoothing out clothing, goods, - etc. - - =Magneto.= A dynamo which has the field pieces, or - poles made of permanent magnets. - - =Magnetism.= That quality, or agency by virtue of - which certain bodies are productive of - magnetic force. - - =Manifestation.= Showing or explaining a state of - things; an outward show. - - =Make and Break.= An ignition system, which provides - for throwing in and cutting out an - electric circuit. - - =Manifold.= A system of piping whereby the exhausts of - a gasoline engine are brought together - into one common discharge. - - =Manganese.= A hard, brittle, grayish white metallic - element, used in the manufacture of - paints and of glass, and also for - alloying metals. - - =Manually.= Doing things by hand; muscular activity. - - =Material.= Substances and parts from which articles - are made. - - =Mechanically.= Doing things by means of machinery, or - in some regular order. - - =Mobility.= The capacity to move about. - - =Multiple.= A figure used a certain number of times, - is said to be a multiple of a number, - if it will divide the number equally. - Thus 4 is a multiple of 16; 3 is a - multiple of 9, and so on. - - - =Neutral.= Neither; not in favor of any party or - thing. - - =Normal.= As usual; in the regular way; without - varying from the ordinary manner. - - - =Ohm's Law.= In electricity, it is expressed as - follows: 1. The current strength is - equal to the electromotive force - divided by its resistance. 2. The - electromotive force is equal to the - current strength multiplied by the - resistance. 3. The resistance is equal - to the electromotive force divided by - the current strength. - - =Oscillating.= Moving to and fro, like a pendulum. - - =Orifice.= An opening; a hole. - - =Organism.= Any part of the body, or any small germ or - animalcule. - - =Oxidation.= The action of air or oxygen on any - material, is called oxidation. Thus - rust on iron is called oxidation. - - =Oxygen.= A colorless, tasteless gas, the most - important in nature, called the - acid-maker of the universe, as it - unites with all substances, and - produces either an acid, an alkali, or - a neutral compound. - - - =Parallel.= Two lines are said to be parallel, when - they are lying side by side and are - equally distant from each other from - end to end. - - =Pendulum.= A bar suspended at one end to a pivot pin, - and having its lower end free to swing - to and fro. - - =Penstock.= A reservoir designed to receive and - discharge water into a turbine or other - form of water wheel. - - =Permanent.= That which will last; not easily stopped. - - =Pestle.= An implement of stone or metal used for - breaking and grinding up chemicals, and - other material in a mortar. - - =Petroleum.= A liquid fuel product, found in many - places, its component parts being about - 15 per cent. hydrogen and 85 per cent. - carbon. - - =Perimeter.= The outer rim, or circle. - - =Piston.= That part of an engine which is attached to - the piston rod. - - =Pinion.= A small gear wheel driven by a larger gear - wheel. - - =Platinum.= An exceedingly hard metal, used in places - for electrical work where the current - is liable to burn out ordinary - conductors. - - =Polarity.= The quality of having opposite poles. - - =Pre-heating.= To heat before the ordinary process of - heating commences. - - =Ponderous.= Large; heavy; difficult to handle. - - =Port.= In nautical parlance the left side of a - vessel; the larboard side; also an - opening, or a conduit for the - transmission of gas or liquid. - - =Pop valve.= A valve designed to open and allow escape - of the imprisoned gases when the latter - reach a certain pressure. - - =Potential.= The power; the term used in electricity - to denote the energy in a motor. - - =Plurality.= More than one; many. - - =Precipice.= A high and very steep cliff. - - =Pressure.= The act of one body placed in contact with - another and acting against it or - against each other. - - =Precaution.= Taking great care; being assured of safety. - - =Primary A cell, or a number of cells, made - battery.= of pairs of metallic couples, immersed - in an electrolyte of either an acid or - an alkali. - - =Proney Brake.= A device for testing machinery and - determining power, by means of - friction. - - =Primeval.= The earliest; the first; of a low order. - - =Proportion.= The relation of one thing or number, to - another; comparative merit. - - =Proximity.= Close to; near at hand. - - - =Quadruple.= Four times. - - - =Rack.= A bar having a number of teeth, to serve as a - step or measure for a pawl, or a - toothed wheel. - - =Radial.= Extending out from the center. - - =Radiation.= The property of many substances to give - forth heat or cold, or to disperse it. - - =Rarified.= Made less than the normal pressure, as - air, which is not as dense at a high as - at a low altitude. - - =Receiver.= In telephone apparatus, that part of the - mechanism which transmits the message - to the ear. - - =Rectilinear.= A right line; a straight direction - forwardly. - - =Reaction.= A force which is counter to a movement in - another direction. - - =Refrigeration.= Cooling process; the art of freezing. - - =Refined.= Purifying; improved. - - =Re-heating.= The process of further heating or - increasing the temperature during the - progress of the work. - - =Requisite.= The necessary part; the requirement. - - =Residue.= The balance; what is left over. - - =Resistance.= Opposition; against. - - =Reciprocating.= One for the other; moving from one - side to the other. - - =Refinement.= Chastity of thought, taste, manner, or - actions. - - =Retort.= A vigorous answer. A receptacle adapted to - stand a high heat. - - =Revolution.= Turning, like the earth in its orbit. - - =Rock Shaft.= A shaft which turns part of its rotation - in one direction, and then turns in the - other direction. - - =Rotation.= The turning of a wheel on its axle; the - rotation of the earth on its axis each - day. Distinguishing from revolution - which is a swinging of the entire body - of the earth around the sun in its orbit. - - - =Sal-Ammoniac.= A white metallic element. - - =Scavenging.= To clean out; to scour. - - =Secondary A battery which is charged with a - Battery.= current, and then gives forth an - electric current of a definite amount. - It is also known as an _accumulator_, - since its elements continue to - accumulate electric energy. - - =Secondary coil.= In induction coils two wire - wrappings are necessary, the first - winding being, usually, of heavy wire, - and called the primary; the second - winding is of finer wire, and is called - the secondary coil. - - =Sector.= An A-shaped piece cut from a disk; - distinguish this from a segment, which - is a part cut off from a disk by a - single straight line. - - =Secondary.= Occupying a second place; not of the - first kind, or place. - - =Segment.= A part cut off from a disk, by a single - line; the part of a circle included - within a chord and its arc. - - =Sewerage.= The conveyance of waste matter from a - building. - - =Sinuous.= Systematic draining by means of pipes or - conduits. Characterized by bends, or - curves, or a serpentine curving, or - wave-like outline. - - =Slide Valve.= A form, which moves along a flat - surface through which the duct is formed. - - =Solution.= A liquid having therein different - substances mixed together. - - =Sprayer.= To eject; to send forth in small particles. - - =Stability.= Fixed; strength to stand without support. - - =Stupendous.= Immense; large; much beyond the largest - of the kind. - - =Standard.= A sample of the measure or extent; a type - or a model. - - =Stratify.= To deposit, form, or range in strata. - - =Super Heating.= To heat up beyond the ordinary or - normal point. - - =Subtle.= Crafty; made of light material; daintily - constructed. - - =Supersede.= In place of; to take the place of. - - =Susceptible.= Capable of being changed or influenced. - - =Suspension.= Hanging; floating of a body in fluid. - - =Suction.= The production of a partial vacuum in a - space connected with a fluid under - pressure. - - - =Terminal.= The end; the last part. - - =Technical.= Specially or exclusively pertaining to - some art or subject. - - =Theoretical.= That which is speculative, as - distinguished from practical. - - =Throttle Valve.= A device which is designed to cut - off the flow of a fluid. - - =Throttling.= The closing of a port; the cutting down - of a supply. - - =Transformation.= A complete change; made over into - something else. - - =Transmit.= To convey; to send to another part. - - =Transference.= To convey to another part; the change - from one thing to another. - - =Transferred.= Put over. - - =Triple.= Three; thrice. - - =Turbine.= To turn; a form of water wheel and steam - engine, where the fluid impinges - against the blades arranged around the - perimeter of the wheel. - - =Tubular.= Hollowed; like a pipe. - - =Two-Cycle.= A gasoline engine, in which the - compressed hydro-carbon gases are fired - every turn of the crank shaft. - - =Typical.= The nature or characteristics of a type. - - - =Undershot.= A type of wheel in which the water shoots - past and against the blades on the - lower side. - - =Unison.= Together; conjointly; acting with each - other. - - =Universally.= All over the world; throughout all - space. - - =Utility.= Use; that which is valuable or of service. - - - =Vacuum.= That part from which all material is taken; - in a limited sense, air, which has less - density than the normal. - - =Vaporizing.= To convert into gas, usually by heat. - - =Variable.= With differing characteristics; changeable. - - =Venturi Tube.= A form of tube which has a contracted - part between its ends. - - =Vertical.= In the direction of a line which points to - the center of the earth. - - =Vibrator Coil.= In electrical devices used in the - ignition systems of certain types of - gasoline engines, a winding is provided - on a metallic core, which has an - armature that is made so it will vibrate. - - =Volt.= The pressure of an electric current; the unit - of electromotive force. - - =Voltage.= Electromotive force as expressed in volts. - - =Volt Meter.= An instrument for indicating the voltage - of an electric circuit. - - - =Watt.= The electrical unit of the rate of working in - an electric circuit, the rate being the - electromotive force of one volt, and - the intensity of one ampere. - - =Weight.= The measure of the force toward the center - of the earth, due to gravity. - - =Winnowed.= Taken out; sifted from. - - =Wiping Bar.= A metallic piece which rests against a - moving wheel and designed to take a current - from or to transmit it to the wheel. - - - - -The Motor Boys Series - -(_Trade Mark, Reg. U. S. Pat. Of._) - -By CLARENCE YOUNG - -12mo. Illustrated. Price per volume, 60 cents, postpaid. - - -[Illustration] - -=The Motor Boys= - _or Chums Through Thick and Thin_ - -=The Motor Boys Overland= - _or A Lone Trip for Fun and Fortune_ - -=The Motor Boys in Mexico.= - _or The Secret of The Buried City_ - -=The Motor Boys Across the Plains= - _or The Hermit of Lost Lake_ - -[Illustration] - -=The Motor Boys Afloat= - _or The Stirring Cruise of the - Dartaway_ - -=The Motor Boys on the Atlantic= - _or The Mystery of the Lighthouse_ - -=The Motor Boys in Strange Waters= - _or Lost in a Floating Forest_ - -=The Motor Boys on the Pacific= - _or The Young Derelict Hunters_ - -[Illustration] - -=The Motor Boys in the Clouds= - _or A Trip for Fame and Fortune_ - -=The Motor Boys Over the Rockies= - _or A Mystery of the Air_ - -=The Motor Boys Over the Ocean= - _or A Marvellous Rescue in Mid-Air_ - -=The Motor Boys on the Wing= - _or Seeking the Airship Treasure_ - -[Illustration] - -=The Motor Boys After a Fortune= - _or The Hut on Snake Island_ - -=The Motor Boys on the Border= - _or Sixty Nuggets of Gold_ - -=The Motor Boys Under the Sea= - _or From Airship to Submarine_ - -=The Motor Boys on Road and River= - (_new_) _or Racing to Save a Life_ - - - CUPPLES & LEON CO., Publishers, NEW YORK - - - - -Up-to-date Baseball Stories - -Baseball Joe Series - -By LESTER CHADWICK - -Author of "The College Sports Series" - -12mo. Illustrated. Price per volume, 60 cents, postpaid. - - * * * * * - -[Illustration] - -Ever since the success of Mr. Chadwick's "College Sports Series" we have -been urged to get him to write a series dealing exclusively with -baseball, a subject in which he is unexcelled by any living American -author or coach. - - -Baseball Joe of the Silver Stars - -_or The Rivals of Riverside_ - -In this volume, the first of the series, Joe is introduced as an -everyday country boy who loves to play baseball and is particularly -anxious to make his mark as a pitcher. He finds it almost impossible to -get on the local nine, but, after a struggle, he succeeds. A splendid -picture of the great national game in the smaller towns of our country. - - -Baseball Joe on the School Nine - -_or Pitching for the Blue Banner_ - -Joe's great ambition was to go to boarding school and play on the school -team. He got to boarding school but found it harder making the team -there than it was getting on the nine at home. He fought his way along, -and at last saw his chance and took it, and made good. - - -Baseball Joe at Yale - -_or Pitching for the College Championship_ - -From a preparatory school Baseball Joe goes to Yale University. He makes -the freshman nine and in his second year becomes a varsity pitcher and -pitches in several big games. - - -Baseball Joe in the Central League - -_or Making Good as a Professional Pitcher_ - -In this volume the scene of action is shifted from Yale College to a -baseball league of our central states. Baseball Joe's work in the box -for Old Eli had been noted by one of the managers and Joe gets an offer -he cannot resist. Joe accepts the offer and makes good. - - -Baseball Joe in the Big League - -_or A Young Pitcher's Hardest Struggle_ - -From the Central League Joe is drafted into the St. Louis Nationals. At -first he has little to do in the pitcher's box, but gradually he wins -favor. A corking baseball story that fans, both young and old, will -enjoy. - - * * * * * - - CUPPLES & LEON CO., Publishers, NEW YORK - - - - -The Racer Boys Series - -by CLARENCE YOUNG - -Author of "The Motor Boys Series", "Jack Ranger Series", etc. etc. - -Fine cloth binding. Illustrated. Price per volume, 60c postpaid. - - * * * * * - -[Illustration] - -The announcement of a new series of stories by Mr. Clarence Young is -always hailed with delight by boys and girls throughout the country, and -we predict an even greater success for these new books, than that now -enjoyed by the "Motor Boys Series." - -=The Racer Boys= -or The Mystery of the Wreck - -This, the first volume of the series, tells who the Racer Boys were and -how they chanced to be out on the ocean in a great storm. Adventures -follow in rapid succession in a manner that only Mr. Young can describe. - -=The Racer Boys At Boarding School= -or Striving for the Championship - -When the Racer Boys arrived at the school everything was at a -standstill, and the students lacked ambition and leadership. The Racers -took hold with a will, got their father to aid the head of the school -financially, and then reorganized the football team. - -=The Racer Boys To The Rescue= -or Stirring Days in a Winter Camp - -Here is a story filled with the spirit of good times in winter--skating, -ice-boating and hunting. - -=The Racer Boys on The Prairies= -or The Treasure of Golden Peak - -From their boarding school the Racer Boys accept an invitation to visit -a ranch in the West. - -=The Racer Boys on Guard= -or The Rebellion of Riverview Hall - -Once more the boys are back at boarding school, where they have many -frolics, and enter more than one athletic contest. - -=The Racer Boys Forging Ahead= -or The Rivals of the School League - -Once more the Racer Boys go back to Riverview Hall, to meet their many -chums as well as several enemies. Athletics play an important part in -this volume, and the rivalry is keen from start to finish. The Racer -Boys show what they can do under the most trying circumstances. - - * * * * * - - CUPPLES & LEON CO., Publishers, NEW YORK - - - - -The Dorothy Dale Series - -By MARGARET PENROSE - -Author of "The Motor Girls Series" - -12mo. Illustrated. Price per volume, 60 cents, postpaid. - - * * * * * - -[Illustration] - -Dorothy Dale: A Girl of To-Day - -Dorothy is the daughter of an old Civil War veteran who is running a -weekly newspaper in a small Eastern town. When her father falls sick, -the girl shows what she can do to support the family. - -Dorothy Dale at Glenwood School - -More prosperous times have come to the Dale family, and Major Dale -resolves to send Dorothy to a boarding school. - -Dorothy Dale's Great Secret - -A splendid story of one girl's devotion to another. How Dorothy kept the -secret makes an absorbing story. - -Dorothy Dale and Her Chums - -A story of school life, and of strange adventures among the gypsies. - -Dorothy Dale's Queer Holidays - -Relates the details of a mystery that surrounded Tanglewood Park. - -Dorothy Dale's Camping Days - -Many things happen, from the time Dorothy and her chums are met coming -down the hillside on a treacherous load of hay. - -Dorothy Dale's School Rivals - -Dorothy and her chum, Tavia, return to Glenwood School. A new student -becomes Dorothy's rival and troubles at home add to her difficulties. - -Dorothy Dale in the City - -Dorothy is invited to New York City by her aunt. This tale presents a -clever picture of life in New York as it appears to one who has never -before visited the Metropolis. - -Dorothy Dale's Promise - -Strange indeed was the promise and given under strange circumstances. -Only a girl as strong of purpose as was Dorothy Dale would have -undertaken the task she set for herself. - -Dorothy Dale in the West - -Dorothy's father and her aunt inherited a valuable tract of land in the -West. The aunt, Dorothy and Tavia, made a long journey to visit the -place, where they had many adventures. - - * * * * * - - CUPPLES & LEON CO., Publishers, NEW YORK - - - - -The Motor Girls Series - -By MARGARET PENROSE - -Author of the highly successful "Dorothy Dale Series" - -12mo. Illustrated. Price per volume, 60 cents, postpaid. - - * * * * * - -[Illustration] - -The Motor Girls -_or A Mystery of the Road_ - -When Cora Kimball got her touring car she did not imagine so many -adventures were in store for her. A tale all wide awake girls will -appreciate. - -The Motor Girls on a Tour -_or Keeping a Strange Promise_ - -A great many things happen in this volume. A precious heirloom is -missing, and how it was traced up is told with absorbing interest. - -The Motor Girls at Lookout Beach -_or In Quest of the Runaways_ - -There was a great excitement when the Motor Girls decided to go to -Lookout Beach for the summer. - -The Motor Girls Through New England -_or Held by the Gypsies_ - -A strong story and one which will make this series more popular than -ever. The girls go on a motoring trip through New England. - -The Motor Girls on Cedar Lake -_or The Hermit of Fern Island_ - -How Cora and her chums went camping on the lake shore and how they took -trips in their motor boat, are told in a way all girls will enjoy. - -The Motor Girls on the Coast -_or The Waif from the Sea_ - -The scene is shifted to the sea coast where the girls pay a visit. They -have their motor boat with them and go out for many good times. - -The Motor Girls on Crystal Bay -_or The Secret of the Red Oar_ - -More jolly times, on the water and at a cute little bungalow on the -shore of the bay. A tale that will interest all girls. - -The Motor Girls on Waters Blue -_or The Strange Cruise of the Tartar_ - -Before the girls started on a long cruise down to the West Indies, they -fell in with a foreign girl and she informed them that her father was -being held a political prisoner on one of the islands. A story that is -full of fun as well as mystery. - - * * * * * - - CUPPLES & LEON CO., Publishers, NEW YORK - - - - -Ruth Fielding Series - -By ALICE B. EMERSON - -12mo. Illustrated. Price per volume, 40 cents, postpaid. - - * * * * * - -[Illustration] - -Ruth Fielding of The Red Mill -_or Jaspar Parloe's Secret_ - -Telling how Ruth, an orphan girl, came to live with her miserly uncle, -and how the girl's sunny disposition melted the old miller's heart. - -Ruth Fielding at Briarwood Hall -_or Solving the Campus Mystery_ - -Ruth was sent by her uncle to boarding school. She made many friends, -also one enemy, who made much trouble for her. - -Ruth Fielding at Snow Camp -_or Lost in the Backwoods_ - -A thrilling tale of adventures in the backwoods in winter, is told in a -manner to interest every girl. - -Ruth Fielding at Lighthouse Point -_or Nita, the Girl Castaway_ - -From boarding school the scene is shifted to the Atlantic Coast, where -Ruth goes for a summer vacation with some chums. - -Ruth Fielding at Silver Ranch -_or Schoolgirls Among the Cowboys_ - -A story with a western flavor. How the girls came to the rescue of -Bashful Ike, the cowboy, is told in a way that is most absorbing. - -Ruth Fielding on Cliff Island -_or The Old Hunter's Treasure Box_ - -Ruth and her friends go to Cliff Island, and there have many good times -during the winter season. - -Ruth Fielding at Sunrise Farm -_or What Became of the Raby Orphans_ - -Jolly good times at a farmhouse in the country, where Ruth rescues two -orphan children who ran away. - -Ruth Fielding and the Gypsies -_or The Missing Pearl Necklace_ - -This volume tells of stirring adventures at a Gypsy encampment, of a -missing heirloom, and how Ruth has it restored to its owner. - - * * * * * - - CUPPLES & LEON CO., Publishers, NEW YORK - - - - -The Dave Dashaway Series - -By ROY ROCKWOOD - -Author of the "Speedwell Boys Series" and the "Great Marvel Series." - -12mo. Illustrated. Price per volume, 40 cents, postpaid. - - * * * * * - -Never was there a more clever young aviator than Dave Dashaway. All -up-to-date lads will surely wish to read about him. - - * * * * * - -[Illustration] - -Dave Dashaway the Young Aviator -_or In the Clouds for Fame and Fortune_ - -This initial volume tells how the hero ran away from his miserly -guardian, fell in with a successful airman, and became a young aviator -of note. - -Dave Dashaway and His Hydroplane -_or Daring Adventures Over the Great Lakes_ - -Showing how Dave continued his career as a birdman and had many -adventures over the Great Lakes, and how he foiled the plans of some -Canadian smugglers. - -Dave Dashaway and His Giant Airship -_or A Marvellous Trip Across the Atlantic_ - -How the giant airship was constructed and how the daring young aviator -and his friends made the hazardous journey through the clouds from the -new world to the old, is told in a way to hold the reader spellbound. - -Dave Dashaway Around the World -_or A Young Yankee Aviator Among Many Nations_ - -An absorbing tale of a great air flight around the world, of adventures -in Alaska, Siberia and elsewhere. A true to life picture of what may be -accomplished in the near future. - -Dave Dashaway: Air Champion -_or Wizard Work in the Clouds_ - -Dave makes several daring trips, and then enters a contest for a big -prize. An aviation tale thrilling in the extreme. - - * * * * * - - CUPPLES & LEON CO., Publishers, NEW YORK - - - - -The Speedwell Boys Series - -By ROY ROCKWOOD - -Author of "The Dave Dashaway Series," "Great Marvel Series," etc. - -12mo. Illustrated. Price per volume, 40 cents, postpaid. - - * * * * * - -All boys who love to be on the go will welcome the Speedwell boys. They -are clean cut and loyal lads. - - * * * * * - -[Illustration] - -The Speedwell Boys on Motor Cycles -_or The Mystery of a Great Conflagration_ - -The lads were poor, but they did a rich man a great service and he -presented them with their motor cycles. What a great fire led to is -exceedingly well told. - -The Speedwell Boys and Their Racing Auto -_or A Run for the Golden Cup_ - -A tale of automobiling and of intense rivalry on the road. There was an -endurance run and the boys entered the contest. On the run they rounded -up some men who were wanted by the law. - -The Speedwell Boys and Their Power Launch -_or To the Rescue of the Castaways_ - -Here is an unusual story. There was a wreck, and the lads, in their -power launch, set out to the rescue. A vivid picture of a great storm -adds to the interest of the tale. - -The Speedwell Boys in a Submarine -_or The Lost Treasure of Rocky Cove_ - -An old sailor knows of a treasure lost under water because of a cliff -falling into the sea. The boys get a chance to go out in a submarine and -they make a hunt for the treasure. - -The Speedwell Boys and Their Ice Racer -_or The Perils of a Great Blizzard_ - -The boys had an idea for a new sort of iceboat, to be run by combined -wind and motor power. How they built the craft, and what fine times they -had on board of it, is well related. - - * * * * * - - CUPPLES & LEON CO., Publishers, NEW YORK - - * * * * * - - - - - - - -End of the Project Gutenberg EBook of Motors, by James Slough Zerbe - -*** END OF THIS PROJECT GUTENBERG EBOOK MOTORS *** - -***** This file should be named 42369-8.txt or 42369-8.zip ***** -This and all associated files of various formats will be found in: - http://www.gutenberg.org/4/2/3/6/42369/ - -Produced by Greg Bergquist, Tom Cosmas and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from images generously made available -by The Internet Archive/American Libraries.) - - -Updated editions will replace the previous one--the old editions -will be renamed. - -Creating the works from public domain print editions means that no -one owns a United States copyright in these works, so the Foundation -(and you!) can copy and distribute it in the United States without -permission and without paying copyright royalties. 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