diff options
Diffstat (limited to '42369-0.txt')
| -rw-r--r-- | 42369-0.txt | 6252 |
1 files changed, 6252 insertions, 0 deletions
diff --git a/42369-0.txt b/42369-0.txt new file mode 100644 index 0000000..82f99a6 --- /dev/null +++ b/42369-0.txt @@ -0,0 +1,6252 @@ +*** START OF THE PROJECT GUTENBERG EBOOK 42369 *** + +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 THE PROJECT GUTENBERG EBOOK 42369 *** |