EVERY BOY'S MECHANICAL LIBRARY Every Boy's Mechanical Library 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 draw- ings, this volume will be appreciated. It sets forth the ground- work on which power is based, and includes steam generators, and engines, as well as wind and water motors, and thoroughly de- scribes the Internal Combustion Engine. It has special chapters on Carbureters, Ignition, and Electrical systems used, and par- ticularly points out the parts and fittings required with all de- vices needed in enginry. It explains the value of compounding, condensing, pre-heating and expansion, together with the methods used to calculate and transmit power. Numerous original illus- trations. 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 in- tended 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 re- quired. 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 outlet plug tv/frtn spa //VLETVALV { i/alve seat /a/let tube CHAMBER gasfvel /ML £7 tv/tre/MAC/ti. /v/t/st P//V /VAT EH SPACF CYLINDER INLET VALVE L/F7 P/STOA CONNECTING ROD CRANK ARM- CRANK CASE ELY WHEEL WATER OUTLET VALVE OPENING \ COMB UST/PA CHAMBER EXHAUST VALVE WATER SPACE EXHAUST V/l LYE CHAMBER /IS EXHAUST 'EXAAU ST VALVE PACKING RING WATER SPACE 'USEABLE COLLAR CAM INLET CAM SHAFT INLET CA/H SHAFT GEAR GEAR 2ETWEEA CAM SAAFES CAM SAAET EX.HAUS T VAL VE CAM fXAAUST CAMSHAFFGEAR REMOVAM E PART OFCRA/VH CASE CRANK SHAFT Every Boy's Mechanical Library MOTORS . S. Z] BY J. Si ZERBE, M.E. Author of Aeroplanes — Automobiles ILLUSTRATED NEW YORK CUPPLES & LEON COMPANY - ^ Copyright, 1915, by CUPPLES & LEON COMPANY l£ -76 bt *.£* APR 17 1915 ©CI.A397603 ' CONTENTS PAGE Introductory 1 The Subject. The Inquisitive Trait. The Keasons 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 Move- ments. 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 Grav- ity. 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 absorbant 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. Impor- tance of the Valve. Expanding the Steam. Balanced Valve. Rotary Valve. Engine Accessories. Efficiency of Engines. How Steam acts in a Cylinder. Indi- cating the Engine. Mean Efficiency. Calculating Horse Power. Condensation. Atmospheric Pressure. CONTENTS PAGE The Condenser. Pre-heating. Superheaters. Com- pounding. 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. Oxida- tion. The Hydro-Carbon Gases. Oxygen and the At- mosphere. Internal Combustion. Vaporizing Fuel. Explosion by Heat Compression. How Compression Heats. Elasticity of Gases. Advantages of Compres- sion. 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 Construc- tion. 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. Charac- teristics of Electricity. Make and Break System. Voltage. High and Low Voltage. Low Tension method. Disadvantages of Make and Break. Am- peres. Resistance. Direct Current. Alternating Cur- rent. Induction. Generating Electricity. Primary Battery. Making a Dry Cell. Energy in a cell. Wiring Methods. Series Connection. Multiple Con- nection. 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. CONTENTS PAGE 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 Con- denser. Operations of a Vibrator Coil. The Distribu- tor. 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 XL 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 En- gines. 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 Cohesive- CONTENTS PAGE ness in Countries Without Power. The Railroad as a Factor in Civilization. The Wonderful Effects of Power. England as a User of Power. The Automo- bile. 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 Measure- ment of Heat. Caloric. Material Theory. Heat Transmitted in Three Ways. Conduction. Convec- tion. 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-Cyele Engine. First position 75 27. Four-Cycle Engine. Second position 7"> 28. Four-Cycle Engine. Third position 76 29. Four-Cycle Engine. Fourth position 76 30. Valve Grinding 81 LIST OF ILLUSTRATIONS FIG. PAGE 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 Ill 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 LIST OF ILLUSTRATIONS FIG. PAGE 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 LIST OF ILLUSTEATIONS FIG. PAGE 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 1 13. 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 mechan- ism 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. 1 2 INTRODUCTORY 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 mathe- matics 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 present- ing the subject. The opening chapters, which treat of the funda- mentals, 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 struc- tures of the different parts and devices in the vari- ous types of motors. The object is to explain power in its various phases, how derived, and the manner in which ad- vantage 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 im- INTRODUCTORY 3 pressed me with the universality of one trait in boys, namely, that of inquisitiveness. Put a ma- chine before a boy and allow him to dissect it, and his curiosity will prompt him to question the mo- tive for the particular construction of each part of its make-up. The Reasons for Doing Things. — He is inter- ested 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 re- call a farmer's boy whose curiosity led him to in- vestigate 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 opera- tion to a group of boys, and men, too, in which he 4 INTRODUCTORY used the knot itself to explain how the various fingers and levers cooperated to perform their functions. It was an open book to Mm, 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 knowl- edge 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 sim- ple question is asked over and over again. To reply means pages of answers and volumes of ex- planations. 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 ren- der 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 6 MOTORS FOR BOYS each stroke. In doing so two motions were re- quired in opposite directions, and it took thou- sands 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 some- thing 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 MOTORS AND MOTIVE POWER 7 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 rep- resented 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 dis- lodge 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 repre- sents the capacity to do work, while Kinetic Energy is the actual performance of work. Friction. — In every form of energy there is al- ways 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. 8 MOTORS FOR BOYS When a wheel travels over the ground friction is ever present. The dislodging of the stone re- quired 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 grav- ity 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 in- crease 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 mul- tiplying 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 MOTOKS AND MOTIVE POWER 9 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 re- sisting 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 mo- tion, by the change of kinetic into potential en- ergy, or vice versa, but the sum total of the en- ergy 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 direc- tion was converted into another form of energy, 10 MOTORS FOR BOYS 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 per- form 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 direc- tion 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 chafT, 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 move- ment was brought about. Movements in Nature. — All movements in na- ture are simple ones, of which the following are illustrations : MOTORS AND MOTIVE POWER 11 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 in- tervals, and at such amplitudes as are required to perform the necessary work. Kinds of Potential Eneegy. — Now, materials have within themselves potential energy of vari- ous 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 ex- pansion 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 12 MOTOKS FOE BOYS 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 addi- tional, 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 mov- ing 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 con- trolled. The latter is more available for two reasons : First: Economy in the use of water. Second : Ability to control the speed or move- ment of the motor. With running or falling streams a large surface MOTORS AND MOTIVE POWER 13 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. T^UfJ. Undeiithoi- Wkeeh 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 tur- bine type. The word is derived from the Latin word turbo, meaning to whirl, like a top. This is a 14 MOTORS FOR BOYS type of wheel mounted on the lower end of a verti- cal 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 JTtg.2. Oi/erAhnt TJ/hffl the tangentially-formed conduit into the drum, and strike the blades of the wheel. A column of water one inch square and twenty- eight inches high weighs one pound, — or, to ex- press it in another way, the pressure at the bot- MOTORS AND MOTIVE POWER 15 torn 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 x 12 inches, and also the blades be 12 x 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 it- self 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 dis- tance 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 16 MOTORS FOR BOYS 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 X 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% 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 MOTORS AND MOTIVE POWER 17 the main factor, 33,000 pounds, and this multi- plied 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 sec- ond, 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 impor- tant, 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 sec- onds, 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 antag- 18 MOTORS FOR BOYS onizes the force of gravity it is constantly utiliz- ing the laws of gravitation. Utilizing the Pull of Gravity. — The boy la- boriously 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 run- ning stream ; the moving winds ; the tides ; the ex- pansive force of all materials under heat, are brought into play to counteract the great pre- vailing 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 utiliza- tion 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. — Grav- ity, that action which seeks to draw all matter toward the center of the earth, is termed centri- MOTORS AND MOTIVE POWER 19 petal force. But as the earth rotates on its axis another force is exerted which tends to throw sub- stances 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 regu- lated. 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 20 MOTOKS FOR BOYS 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 Powee of Motoks. — This de- velopment 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 ob- structions, 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, occu- pies second place. Experimenting. — The great improvements have been made by building and testing; the advance has been step by step. Sometimes a most impor- tant 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 hun- dred years there was no striking improvement in the valve. The various types of sliding and rock- ing valves were modified and refined until it was assumed that they typified perfection. At one MOTOES AND MOTIVE POWER 21 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 re- garded as epochs in the production of motors. CHAPTEE n 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, ex- cept 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 ma- chinery 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 or- ganism, was, really, the last to receive due con- sideration 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 Absorbant of Heat. — Water has the capacity to absorb a greater amount of heat 22 THE STEAM GENERATOR 23 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 lat- ter absorbs the heat so rapidly that the tempera- ture of the metal is kept near the boiling point of water, which is 212 degrees. Notwithstanding the great heat-absorbing qual- ities 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 pre- sent as large an area of water as possible to the heat of the burning fuel. How that was accom- plished 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 24 MOTORS FOR BOYS types which have been adapted to meet this re- quirement. The Cylindrical Boilee. — 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. In such a type of boiler it would be impossible T^JQ. 3. Primitive Zollev 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 THE STEAM GENERATOR 25 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. 'T^ig. 4. nefurx, Tulula r toiler . T^ig.d. Cornish , or Scotch toiler . The Coenish Boilee. — One of the most impor- tant inventions in the generation of steam was the Cornish boiler, which for many years was the rec- ognized 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. 26 MOTORS FOR BOYS 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 numer- ous 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 diametri- cally the diameter of the fire boxes would be re- duced 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 improve- ment. THE STEAM GENERATOR 27 The Water Tube Boiler.— In the early days of the development of boilers, the nniversal practice was to have the products of combustion pass through the flues or the tubes. But quick genera- tion of steam, and high pressures, necessitated a T^ig, 6. Wafer Tule Boiler . Z7nduiew . 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. 28 MOTORS FOR BOYS This form of boiler had two distinct advantages. First, an immense surface of water could be pro- vided 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 wa- ter 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 plu- rality of tubes D. It will thus be seen that a fire box, or combus- tion 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. THE STEAM GENERATOR 29 As heretofore stated, this type of boiler is de- signed to carry only a small quantity of water, so that it is necessary to have practically a con- stant inflow of feed water, and to economize in this respect the exhaust of the steam engine is JF%g. 7. Mater Tufie toiler , - tiidel/iew : 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 30 MOTORS FOR BOYS adapt them for some particular need. It would be needless to illustrate them, but to show the di- versity 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 con- nected, 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 super- heater, 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 oppo- site 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 hav- ing the construction described, and used for gen- erating steam. Vertical Steam-Boiler. — This is a form of con- struction in which the shell, or both the shell and the tubes, are vertical, and the tubes themselves THE STEAM GENERATOR 31 may be used to convey the products of combus- tion, 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 pos- sible area of water to a heated surface so that the greatest amount of heat from the fuel may be ab- sorbed. CHAPTER III STEAM ENGINES The first steam engine was an exceedingly sim- ple 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 em- ployed 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 Oeiginal Engine. — Figure 8 is a side view 32 STEAM ENGINES 33 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. -vi ^ 3<- T^ig. 6. The Original Engine. jP^tg. 9. /for iz onto! 6eciicn o fTiibe . Steam enters the vertical stem by means of a pipe, and as it rushes up and out through the lat- eral tubes D, it strikes the angles E at the dis- charge ends, so that an impulse is given which drives the ends of the tube in opposite directions. 34 MOTORS FOR BOYS 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 mo- tion 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 Wor- cester, who published an account of such an en- gine 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 de- voted 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 en- ergy developed by the atmospheric pressure. A diagram is given, Fig. 10, showing how en- STEAM ENGINES 35 gines 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. TtyJO. titeam 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 36 MOTORS FOR BOYS above the cylinder, and this was supplied with water from the pump through a pipe L. An- other pipe M from the tank conducted water from the tank to the bottom of the cylinder. The operation of the mechanism was as fol- lows: 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 dur- ing 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 injec- tion 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 per- formed manually, — that is, it had to be done by hand, and boys were usually employed for doing this. When, later on, some bright genius discov- STEAM ENGINES 37 ered that the valve could be turned by the ma- chinery itself, it was regarded as a most wonder- ful 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 verti- cally-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 en- gine, so arranged that the operation of the valves may be readily understood. The cylinder A has 38 MOTORS FOR BOYS 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 ^ig. /J. dimp le Ubii/e 7koUo?i . TYrat - position . 7^1$. ?&.4imple, Value Tnotton . 4er.ondrx>6itior> . C is moved to the position shown in Fig. 12, thereby covering port F and opening port G. 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 STEAM ENGINES 39 from the boiler enters through pipe J and tills 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 improve- ment 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 ar- range the valve as to open or close it at the cor- rect 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 con- 40 MOTORS FOR BOYS structed 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 en- tire stroke was completed. Some engines do this with a fair degree of ac- curacy, 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 design- ing 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 oscil- lating 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 con- stantly turns, is employed where low pressures are used, but it is not effectual with high pres- sures. This is also cylindrical in its structure, and has one or more ports through it, which co- incide with the ports through the walls of the en- gine, v as it turns, and thus opens the port for ad- STEAM ENGINES 41 mitting live steam and closing the discharge port at the same time or at a later period in its rota- tion. 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 stand- point 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 con- sideration. 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 under- stood 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 42 MOTORS FOE BOYS 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. The value of considering and providing for condensation, compression, superheating, re-heat- ing, compounding, and radiation, and to properly arrange the clearance spaces, the steam jackets, the valve adjustments, the sizes of the ports and y/^ //*- tf* O 1 2 3 4 X f 6 7 Pre66u?e6->/o,ooo 4doo £7oo /feo 1600 Jbo /bo 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 per- mitting the expansive power of the steam to drive the piston the rest of the way, needs some ex- planation. As stated in a preceding chapter the work done STEAM ENGINES 43 is estimated in foot pounds. For the purpose of more easily comprehending the manner in which the steam acts, and the value obtained by expan- sion, 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 to 1, which represents a distance of one foot, so that the full pressure of the steam of the boiler, representing 5000 pounds, is ex- erted 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 ex- pansive force alone being depended on. As the pressure of the steam within the cylin- der is now much less and decreases as the piston moves along, we have taken a theoretical indica- tion 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 to 1, moved one 44 MOTORS FOR BOYS 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 sec- onds, 150,000 foot pounds per minute, or about 45 horse power. 2^^. 74. Indicatin g premiere line . This movement of the piston to the right, rep- resented 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 as- certain how much power we have obtained from the engine. To do this an indicator card must be STEAM ENGINES 45 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 un- derstood. In Fig. 15 we have shown a cylinder A, hav- ing 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 46 MOTOES FOR BOYS F connected therewith by a pipe A, and in this cylinder is a piston H, the stem I of which ex- tends 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 al- ways 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 con- stantly 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 STEAM ENGINES 47 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 paragTaph, 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 Hobse 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 trav- els 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 48 MOTORS FOR BOYS 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 refine- ments 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 STEAM ENGINES 49 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% pounds. When a piston moves along and steam is being exhausted from the cylinder, it must act against a pressure of 14% pounds on every square inch of its surface. The problem now is to get rid of that back pres- sure, and the old type engines give a hint how it may be done. Why not condense the steam dis- charged 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 50 MOTORS FOR BOYS operation of the engine. For the purpose of rap- idly 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 de- grees, 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 tempera- ture less than boiling water. The water thus con- verted 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 avail- able 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 specifi- cally, 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 en- gine, so that the steam, in its transit from the boiler to the engine, will be heated up to a high STEAM ENGINES 51 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 tempera- ture 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 im- parted 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 jack- eted, 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 52 MOTORS FOR BOYS 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 pres- sure 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 pres- sure, or, stated in another way, whenever it loses pressure it increases in volume. For that rea- son when steam enters the first cylinder at a pres- sure of say 250 pounds, it may exhaust there- from into the next cylinder at a pressure of 175 pounds, with a corresponding increase in volume. To receive this increased volume, without caus- ing a sensible back pressure on the first cylinder, the second cylinder must be larger in area than STEAM ENGINES 53 the first; in like manner when it issues from the exhaust of the second cylinder at 125 pounds pres- sure, there is again an increase in volume, and so on. Examine Fig. 16, which shows a pair of cylin- ders, A being the high, and B the low pressure cylinders, the exhausts of the high pressure be- E Open. 3 0" Cloded J^iff.JC. Compound 2?n gine . ing connected up with the inlets of the low pres- sure, as indicated by the pipes, C D. The diagram does not show the valve opera- tions 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 54 MOTORS FOR BOYS 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. JDiameter/2 in. 266 JM. Dia?7teter f4 in.. stream. p?e66we Jliamete?- J6%> in. s6feam p?€66ure /gQlfo. 3iwnefer£Oi?i. aom. cAiva o n>i6ton 708 sain. Piston pretewv £7ogolM c/Jrea oF pi&ton &7§$ig, Pidton pre66u?e £6460 Ifo . rfrea cF pid ion /OS 4y. VI 2588Q ZH . direc t, of pi6ion 3006#/n. Ptetion pre6$u7e £ J ,000 Ifo. 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. STEAM ENGINES 55 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 pres- sure of steam decreases at the same temperature it is because it has a greater volume, or a greater volume results. 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 jfL / 2 <3 <4 h tf l^tg. 17. Cha?iging Ih-eS&itre to/o l/e?bci fy 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 move- ment of the steam is of first importance. Pressure and Velocity. — To show the effective- ness of velocity, as compared with pressure, ex- amine Fig. 17. A is a pipe discharging steam at a pressure of 100 pounds. To hold the steam in 56 MOTOES FOR BOYS the pipe would require a pressure of 100 pounds against the disk B, when held at 1, the first posi- tion. Suppose, now, the disk is moved away from the end of the pipe to position 2. The steam, in issu- ing 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. The disk is now moved successively to posi- es tc J^ig. W. Reaction a vczznat Jfir . Z^ig. S<9. Reaction a, oa,i7t6t Surface . tions 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 strik- ing force, which might be called the focal point. A blow pipe exhibits this same phase ; the hot- test point is not at the end of the pipe, but at an area some distance away, called the focal point of heat. STEAM ENGINES 57 The first feature of value, therefore, is to un- derstand 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. J^ig. 20. Ta?bin& < 6fraig7iir filadeA . 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 can- not 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 continu- ally part of its speed to the blade. 58 MOTORS FOR BOYS This is clearly shown in Fig. 21, where the pipe D ejects the stream of steam against the concaved blades B. Many modifications have been made in the shapes of these blades, all de- signed to take advantage of this action. Compounding the Jet. — We may extend the ad- vantages gained by this form of blades, and di- T^ig. 21. CurirzcL 3laclc6 . j> t J ; ; ; J ; t * \ A V X X \ \\ 2^1$. 22. Compound Turbine . verting 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 be- tween the three moving wheels, but the stationary STEAM ENGINES 59 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. CHAPTEE IV FUELS AND COMBUSTION All fuels must be put into a gaseous state be- fore they will burn. This is true of coal as well as of hydro-carbon oils. Neither coal nor petroleum will burn in its na- tive 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. 60 FUELS AND COMBUSTION 61 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 quan- tity of hydrogen. As coal was formed by wood, which, through long process of time became carbonized, it con- tains 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 tempera- tures. Combustion. The term combustion, in its gen- eral 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 ele- ments 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 with- 62 MOTORS FOR BOYS out 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 in- stance 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 with- out 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 add- ing 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 FUELS AND COMBUSTION 63 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 aera- tion, 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 un- derstanding 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 64 MOTORS FOR BOYS 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, evapora- tion is facilitated, and at the same time the proper admixture of air is provided to make a combus- tible 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 ex- plosive 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 pres- sure, and this needs some explanation. Explosion by Compkession. — The study of the compressibility of gases is an interesting one. As we have previously stated, the atoms, compris- ing the gases, are constantly moving among them- selves with great rapidity, so that they bombard the sides of the receiver in which they are con- fined, 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, FUELS AND COMBUSTION 65 the friction of their movements is increased, and heat is evolved. As the pressure becomes greater the heat increases until it is of such in- tensity that the gas ignites, and an explosion fol- lows. 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 correspond- ingly 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 re- ceiver, and thereby produce pressures of several 66 MOTORS FOR BOYS 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 cyl- inder, and thereby a greater and more efficient ac- tion is produced on the piston of the engine on ac- count of quicker combustion and therefore higher gas pressures. The compression, however, rarely if ever ex- ceeds six atmospheres or about 90 pounds per square inch. The Necessity of Compression. — There are two reasons why compression is necessary before ig- niting it. First, because it is essential to put suf- ficient gas in the cylinder to make the engine effi- cient. To illustrate : Suppose we have a cylinder ca- pable 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 FUELS AND COMBUSTION 67 there would be no more fuel in the cylinder in one case than in the other. As however the mean ef- fective pressure, which determines the efficiency of the motor, increases with the compression pres- sure, 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 mix- ing 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-car- bon gases than took place when the gases were traveling through the pipes on their way to the cylinder. CHAPTER V THE INTEKNAL COMBUSTION ENGINE It will be observed that in a steam engine tbe 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 pis- ton. 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 per- manently 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 68 INTERNAL COMBUSTION ENGINE 69 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, pre- vents 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, be- cause, 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 hydro- gen, 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, there- fore, 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 70 MOTORS FOR BOYS 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 move- ment 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 dis- tinguish 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 re- movable 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, INTERNAL COMBUSTION ENGINE 71 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. y^tg.^S. Two - cycle. Tlsitit po6iUon . The piston H is connected up with the rod I, the latter being hinged at a point within the pis- ton, as shown. The crank case has an inlet port, provided with a valve which opens inwardly, so 72 MOTORS FOR BOYS 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 0, 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 per- mits 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, INTERNAL COMBUSTION ENGINE 73 rushes in, and as it strikes the deflecting plate 0, is caused to flow upwardly, and thus helps to drive out the burnt gases remaining at the upper end of the cylinder. Ttt/o - c ycle Engine . T^ig £4. -decondpo6itio?t . 7^.26. Thii-d 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 74 MOTORS FOR BOYS will remain, or that some of the unburnt car- bureted 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 or 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 num- ber of revolutions of the crankshaft; and it dis- penses 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 par- tially 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 tem- perature 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. INTERNAL COMBUSTION ENGINE 75 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. 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 £j2W~ C#cU \£7ngine. 2^10. £6. THrdt potitton Twiggy. Second position 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 76 MOTORS FOR BOYS 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 I/, which 7 r ly./g(g. Third position . TUg.&Q. Fburtt position . opens the valve M in the port that admits the car- bureted air. The other large gear N is mounted on a shaft which carries a cam that engages the lower end of a push rod P, to open the valve Q in the dis- charge port F. It should be observed that the stems I/, P, are made in two parts, with interpos- INTERNAL COMBUSTION ENGINE 77 ing 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 distin- guished 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, 0, 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 be- gins to raise the stem P, and thus opens the dis- charge 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 78 MOTORS FOR BOYS 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 opera- tions thus performed are as follows: First, the explosion, and downward movement of the pis- ton. Second, the upward movement of the pis- ton, 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 compres- sion of the charge of carbureted air. The order of the engine performance may be designated as follows: 1. Impulse. 2. Ex- haust. 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 INTERNAL COMBUSTION ENGINE 79 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 com- pression 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 re- sulting 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. 80 MOTORS FOR BOYS 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 INTERNAL COMBUSTION ENGINE 81 making the various parts. The particular fea- tures which require special care are the valves, which should be ground to fit tightly, the proper fitting of the piston rings, crank shaft and con- necting rod bearings as well as the accurate relin- ing of these bearings. l^ig.dO. Valife 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 82 MOTORS FOR BOYS 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 over- grind. 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 differ- ence 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 CAEBUEETEBS A carbueetee, 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 ex- plained, is of such a character that it remains fixed and will not stratify or condense. Functions of a Cabbueeteb. — 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 expan- sive force is less, and the result is a decrease of power. While it is possible to get a rapid evaporation 83 84 MOTORS FOR BOYS 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 com- bustion. 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 ex- haust 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 CARBURETERS 85 high speeds a lean mixture is desirable, princi- pally because it burns more rapidly than a rich mixture. Types of Cabbubetebs. — There are two distinct types of carbureters, one which sprays the gaso- line 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 car- bureters are designed with the object of mechan- ically presenting the largest possible area of oil to the air, so that the latter will become impreg- nated 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 86 MOTORS FOR BOYS 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 quan- tity 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 construc- tion, 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 mix- ture 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 condi- tion 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 CARBURETERS 87 shall therefore take up the various features essen- tial in the construction of the carbureter, so as to show what steps have been taken to meet the problems arising from varying speeds, differ- ences in the character of the fuel, regulating the T*ig. 8L Carbureter . inflow and mixture of gasoline and air, and ad- justments. So many different types of carbureters have been devised, that it is difficult to select one which typifies all the best elements of construction. 88 MOTOES FOR BOYS In Fig. 31 we have shown a well known con- struction, 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 ven- turi 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 en- larged 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 ad- mitted, the air passing upwardly through vertical CARBURETERS 89 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 0, 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 shoul- der on a vertically-disposed needle valve Q, which has its point in the inlet opening of the pipe R, through w T hich 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 suc- tion. This is the auxiliary air inlet, and the lower spring is actuated only when the engine is run- ning at moderate speeds, but when running at high speed and an additional quantity of air is 90 MOTORS FOR BOYS 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 out- side 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 regu- lated 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 CARBURETERS 91 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 understand- ing 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 ar- ranged 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. 92 MOTORS FOR BOYS This is particularly important when the carbure- ter 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, be- yond 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 par- ticle 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 experi- enced 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. CARBURETERS 93 A carbureter too large will only waste fuel, even after the engine lias 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 or 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 aban- doned, because it is obvious that a single car- bureter will, owing to the continuous suction, sup- ply a mixture of more nearly uniform character than two or more, even though they should sup- ply the mixture to a common manifold. The Throttle. — Much of the economy in run- ning 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 en- gine, is to open the throttle fully half way, and 94 MOTORS FOR BOYS 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 sup- ply- 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 open- ing. 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 impuri- ties when it is poured into the tank. To strain it is the best precaution, and it pays to be particu- lar in this respect. It is surprising to see the CARBURETERS 95 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 ir- regular movement of the engine. The only T^ig. <32. Cai'&ureter remedy is to stop and drain the carbureter. A few drops may cause all the trouble. Types of Carbureters. — In Fig. 32 we show an- other type of carbureter, which is simple in con- struction, and has many desirable features. The cylindrical body of the carbureter, A, has a down- 96 MOTORS FOR BOYS wardly-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-pro- jecting circularly-formed extension E, and the top or cap F of the cylindrical body A has a down- wardly-projecting cylindrical rim Gr which over- laps 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, ca- pable 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 cen- trally through the tube J, while the primary air supply passes through openings 0, surrounding the tube J, downwardly past the slitted opening H, and thence to the discharge port D. CARBURETERS 97 Surrounding* the tubular projections E, Gr, 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 cham- ber 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 advan- 98 MOTORS FOR BOYS tage over the sprayer system, in the particular that the suction of the engine is not depended npon 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. The diagram, Fig. 33, shows a body A, some- what bowl-shaped, with a chambered extension, 7^1 g. S3. -6icrface Cw'Swefv,? : 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 se- CARBURETERS 99 cured 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 there- with a U-shaped tube, the inlet end I being hori- zontally-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 com- municates with the float chamber, and is provided with a drain plug 0. 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. 100 MOTORS FOR BOYS 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 do- ing 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 car- bureter 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 ad- CAEBURETERS 101 justments made while running, while for auto- mobile 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 elec- tricity 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 manifesta- tions, 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. 102 IGNITION. LOW TENSION SYSTEM 103 If a piece of metal lias 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 man- ifestations, 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 elec- trical 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 cur- rent passes along a wire, it does not describe a straight path, but it moves around the conductor in the farm of circles. The current is not con- fined 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, surround- ing 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, 104 MOTORS FOR BOYS 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 ig- nition. Voltage is that quality which gives pres- sure 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 cur- IGNITION. LOW TENSION SYSTEM 105 rent, — 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 be- tween them, and the slightest separation will pre- vent a low current from jumping across. This is not the case with a high tension cur- rent, 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 electri- cal 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 am- peres, — that is, the quantity flowing. A large con- ductor 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. 106 MOTORS FOR BOYS 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 economi- cal to use a small conductor which has small re- sistance, 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 cur- rent, 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 direc- tion 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 cur- rent. All dynamos originally make this kind of current, but the commutator and brushes in the direct current machine change the output method IGNITION. LOW TENSION SYSTEM 107 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 em- ployed for the make and break system, since bat- teries are used as the electrical source. On the other hand the jump spark method em- ploys 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 igni- tion. Generating Electricity. — There are two ways to produce a current for operating an ignition sys- tem, 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-project- ing wing B at one side, to which the conductor is attached; and within, centrally, is a carbon bar 108 MOTORS FOE BOYS C. An electrolyte, which may be either acid or alkali, must be placed within the 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 Carbojz IP=§i-z^ 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 IGNITION. LOW TENSION SYSTEM 109 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 volt- age 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. JF^lO. 36. <6erie-6 Connection Wiring Methods. — As at least six cells are re- quired to operate a coil, the following diagrams will show that number to illustrate the different types of connections. Seeies Connection. — The six cells, Fig. 35, show the carbon electrodes A, of one cell, con- nected by means of a wire B with the zinc elec- trode 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. 110 MOTORS FOR BOYS 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% x 6> which is equal to 9 volts. The amperage, however, is that of one cell, which, in these diagrams, will be as- sumed to be 25. Parallel Connection. — Now examine Fig. 36. In this case the carbon electrodes A are all con- nected up in series, that is, one following the other in a direct line, by wires B, and the zinc 2 r %g.$6. THuZtipZe . or Parallel Connection . electrodes C, are, in like manner, connected up in series with each other by wires D. The differ- ence 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 con- necting 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. IGNITION. LOW TENSION SYSTEM 111 Multiple Connections. — This is also desig- nated 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. The result of this form of connection is to in- crease the voltage equal to that of one cell mul- JSattery Jfat Battery JfoJl ^T^ff- 37, -tierJed - Tnulitple Connection. tipled by the number of cells in one set, and the amperage is determined by that of one cell mul- tiplied 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 con- nected in series, has a voltage equal to 4% 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 112 MOTORS FOR BOYS 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 multi- plied by the amperes a factor is obtained, called Watts. Thus, as each cell has l 1 /^ volts and 25 amperes, their product is SI 1 /** watts. To show that the same energy is present in each form of connection let us compare the watts de- rived from each: Series connection : 9 volts X 25 amperes, equal 225 watts. Parallel connection : iy 2 volts X 150 amperes, equal 225 watts. Series Multiple connection: 4% volts X 50 amperes, equal 225. 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 bat- tery 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 de- creased. It would be well to study the foregoing com- IGNITION. LOW TENSION SYSTEM 113 parative analysis of the three forms of connec- tions, so far as the energy is concerned, because there is an impression that increasing the volt- age, 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. 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. Cell jTty.SS. Ci7cui£ T T e6tirtg . 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 cir- cuit 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 114 MOTORS FOR BOYS the pressure, the power, or the difference of po- tential 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, 2^10.89. MaTcQ £. ContactfoaJzeK 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 ten- sion 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 induc- tion coil, and the other side of the battery has a 132 MOTORS FOR BOYS wire D leading to the contact maker. A switch E is placed in the line of this wire. The other terminal of the primary has a wire F leading to the insulated contact plug Gr of the contact maker. This completes the generating Hi ^£ T^tff. 33. Ty pical Circuiting * Jump tipari I gnition . 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 IGNITION. HIGH TENSION 133 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 ten- sion current is momentarily induced in the sec- ondary, so that the current leaps the gap in the spark plug and makes the spark. Metallic Coke for Induction Coil. — In the previous description of the induction coil it was stated that the spool might be made of wood. J^ig. 64. Metacttc Core, T?tduction Coll . These coils are also provided with metal cores, which can be used to make what is called a vibra- tory coil. The Condenser. — A necessary addition to the circuiting provided by an induction coil, is a con- denser. This is used in the primary circuit to ab- sorb the self -induced current of the primary and thus cause it to oppose the rapid fall of the pri- mary current. The condenser is constructed of a number of tinfoil sheets, of suitable size, each sheet having 134 MOTORS FOE BOYS 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 con- nections 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 T^Q. <$& ConcU>n4p,r . 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. The diagram, Fig. 55, represents the conven- tional form of illustrating it in sketching electri- cal devices. Operation of a Vibrator Coil. — The illustra- tion, Fig. 56, shows the manner in which a vi- brator coil is constructed and operated. The coil comprises a metal core A, the primary winding IGNITION. HIGH TENSION 135 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. The post D holds the end of a vibrating spring jftg. 66. Vibrator Coil and Connection^. 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. 136 MOTORS FOR BOYS The secondary coil N, has the outlet wires 0, 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 de- magnetized, 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 vi- brator arm H goes back and forth with great rapidity. From the foregoing explanations it will be un- derstood 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 ten- sion 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 IGNITION. HIGH TENSION 137 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. Its outer end rests in a bearing plate B, of in- sulating 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 project- ing 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 inter- 138 MOTOES FOR BOYS posed between the shaft and finger so as to pre- vent 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 u www u -=- y J^zg. <58. Circuiting with DiAfributiei - against the hub so as to form continuous contact. A wire leads from the post to one terminal of the secondary coil. Circuiting With Distributer.— The diagram Fig. 58 shows the complete connections of a sys- IGNITION. HIGH TENSION 139 tern 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 con- nected 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 ac- tuates the interrupter I, this being a contact breaker w T hich 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 pri- mary 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 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 mag- neto, 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 suf- 140 MOTORS FOR BOYS ficient 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 mnst be lifted a definite distance within a par- ticular time. The Unit of Time. — The unit of time is either the second, or the minute, usually the latter, be- cause 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 later weighing, 141 142 MOTORS FOR BOYS 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. uco JFlff. 69. IlluZfratiHci the Z/mfrof Time Suppose the cord is 100 feet long, and it re- quires 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 l/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. MECHANICAL DEVICES IN POWER 143 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 w r as 825 pounds. Multiply 100 hy 825, which equals 82,500. This represents foot pounds. As there are 33,000 foot pounds in a horse JF'ig.CO. The I>ronei / Jd?>aXe. power, 82,500 divided by this figure will show that 2y 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 re- winding 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 con- struction : The engine shaft A, Fig. 60, which is giving out its power, and which we want to test, 144 MOTORS FOR BOYS has thereon a pulley B, which turns in the direc- tion 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 ter- minals 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 receptable 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 lit- tle 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, MECHANICAL DEVICES IN POWEK 145 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 % of one foot, and 4 divided by this number, is Y 4", or 1% feet, which is the leverage. Now, let us suppose the weight J is 1200 pounds. This must be multiplied by the leverage, 1% 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. Eeversing Mechanism. — A thorough knowl- edge of the principles underlying the various me- chanical 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 146 MOTOES FOR BOYS 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. j/T'ig. 61. JJouMe Accent? zc7leife7-6ing(xea? \ T^ig. 6£. Reversing Gear , + A/eufia2 . 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 J> 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 ec- MECHANICAL DEVICES IN POWER 147 Gentries 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. J^iff. 6<3. TlcicrMng Gear . Rever6ed . J^ig. 64. &i?igle Eccentric 7tei/er6iw . Geai 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 up- 148 MOTORS FOR BOYS per 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. J^iff- 66 % JBalancect Slide Ifctlve . 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 eccen- tric 0. 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 per- MECHANICAL DEVICES IN POWER 149 taming 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 J^ig. 66. l/cdve C?te6t Double 7>o?t£7x/tau& r beneath an adjustable plate F connected with the top or cover Gr of the valve chest. 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. 150 MOTORS FOR BOYS Balanced Throttle Valve. — Fig. 67 will give a fair idea of the construction of throttle valves, the illustration showing its connection with a sim- ple type of governor. jT'w. 67 balanced Throttla-Volm . 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- MECHANICAL DEVICES IN POWER 151 projecting pendent arms D are hinged. These arms carry balls E at their free ends. The lower part of the stem has thereon a slid- ing collar F, and links G-, with their lower ends M '-& Z^ig. S.d &&zM Governor . hinged to the collar, have their upper ends at- tached 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 con- nected up with the engine throttle, by means of a link L. ' 152 MOTORS FOR BOYS 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 con- structed, some of which operate by gravity, in connection with centrifugal action. Some are made with the balls adapted to swing downwardly, jFYg. 69._ 2ZM Origina l I njector . 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. 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 MECHANICAL DEVICES IN POWER 153 own pressure. It is through the agency of con- densation 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 cham- ber which has a pipe H leading out at one side, through which cold water is drawn into the injec- tor. Surrounding the conical pipes B, C, is a cham- ber I, which has a discharge pipe J. The action of the device is very simple. When steam is per- mitted 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 lat- ter, thereby causing a still greater vacuum, and this vacuum finally becomes so great that, with 154 MOTORS FOE BOYS the inrushing steam, and the rapid movement through the conical tubes, past their separated ends, a full discharge through the drain J is pre- vented. 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 ae- J^ty 70. In/ecto ?' With 7??x>}/aZZe Ctonibijning 7},te tion 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 adjust- ing 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 MECHANICAL DEVICES IN POWER 155 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 opera- tion the tube C may be adjusted the proper dis- tance 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 Watek Heater. — An apparatus of this kind is designed to take the exhaust steam from the engine and condense it, and from the con- denser 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 156 MOTORS FOR BOYS 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. a JT'ig.TL T^eed tlfofer £ea,U? '. 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. MECHANICAL DEVICES IN POWER 157 The steam enters at the port I at the top of the shell, and passes down, as it is condensed, be- ing discharged at the outlet J. CHAPTEE 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 follow- ing illustrations and descriptions will give a good idea of the various types in use. *4 2^g. 78. C7w,ck Value. Check Valve. — Fig. 72 shows a longitudinal section of a check valve, which is designed to pre- 158 VALVES AND VALVE FITTINGS 159 vent the water from returning or backing up from the pressure side. The cylindrical body A is threaded at each end, and has an inclined parti- tion B therein which has a circular aperture. The upper side of the shell has an opening, cQa T^lg. 7& Gate i/afore . 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. 160 MOTORS FOR BOYS In case the valve should leak it may be readily ground by taking the small plug E from the open- ing, and with a screw driver, turning the valve, and thereby fit it snugly on its seat. Gate Valve. — The cylindrical shell A has its nnh J^ig. 74. GZo&e Ifalve . 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. VALVES AND VALVE FITTINGS 161 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 pro- vides a direct passage for the water through the valve body. Globe Valve. — A globe valve has the advan- tage 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 parti- tion B, the intermediate, horizontally-disposed limb of the partition being directly below the open- ing 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 spin- dle. The lower end of the spindle carries the cir- cular 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 162 MOTOES FOR BOYS 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 or- dinary reciprocation engine, a side view of the valve grouping and its connecting mechanism are shown in Fig. 76. 2 rr iff. 76. Corli44 ZfeZv& . 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 el 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 Gr, 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. VALVES AND VALVE FITTINGS 163 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 spin- dles, 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. J^ 7 ^. 76. CorlU& Vcdiv - ope7ati?ig 7ftec/iam4??r. The dash pots L L act is such a manner as to cushion the descent of the links K and thus pre- vent 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 pro- vide a means for closing the valves which are at 164 MOTORS FOR BOYS 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 con- _/%. 77 cdvigle TTaZi/e, . stant release of the exhaust and a constant com- pression to act as a cushion. 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 VALVES AND VALVE FITTINGS 165 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 Hg. 78. Ho-lari / lrtdve T^ig. 70. Ta/o-ajcu/ Rota?:* . side, it would be difficult to repack the gland D without cutting off the steam from the pipe line. Eeferring 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 mis- take is to permit the pressure of the steam to be exerted so that it is constantly acting against the packing of the spindle. Eotary Valves. — Two forms of rotary valves are shown, one as illustrated in Fig. 78, where the 166 MOTORS FOR BOYS 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 open- ing 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. Rotable Engine Valves. — So many different JTlp. SO. Motccrif Tbpe . T^ig. 81. Two-wtu Zciariffi pe, 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 ro- tated 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- VALVES AND VALVE FITTINGS 167 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. T^to. 82. Buttjerfh/Throm . TYq. dS.^rwle Throitte . When the plug turns the* port L serves to con- vey 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 Butter-fly valve, shown in Fig. 82, and this is also used as a 168 MOTORS FOR BOYS 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. In Fig. 83 the wing C is curved, so that by swing- 'Ftg.84. dlvcLe. Throttle. , l^zg. 85. 7h/o - 6lteeT/?jom . ing it around the circle, the opening of the dis- charge pipe D is opened or closed. Another design of throttle is. represented in Fig. 84. One side of the pipe A has a lateral ex- tension 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 VALVES AND VALVE FITTINGS 169 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. JFig. 86. mow -orr iralire . The pipe A from the boiler has cast therewith, or otherwise attached, a collar B, which has a stand- ard 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. 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, 170 MOTOBS FOE BOYS 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 Z^ig. 87. Safety Top Valve. to so arrange it that it may be manually opened, the Safety Pop valve was devised. 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. VALVES AND VALVE FITTINGS 171 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 ad- justing nut I serves to regulate the pressure de- sired before the steam in the boiler can act. CHAPTEE 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 iviper-wheel. The object in all forms of cams is to change motion from a regular into an irregular, or re- versely, and the motion may be accelerated or re- tarded at certain points, or inverted into an in- termittent or reciprocating movement, depend- ent 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 ma- chine, 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 mo- tion but also a turning movement, such forms be- ing largely used to give a quickly rising or fall- ing motion. 172 CAMS AND ECCENTRICS 173 What are called iviper ivheels 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. Cams are also used for cutting machines, or in tracing apparatus where it would be impossible to use ordinary mechanism. All such forms are spe- cial, requiring care and study to make their move- ments co-relate with the other parts of the mech- anism that they are connected up with. Simple Cams. — Fig. 88 shows a form of the most simple character, used, with some modifica- tions, to a larger extent than any other. It is called the heart shaped cam, and is the regular type. 174 MOTOKS FOR BOYS 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. §> Wiper Wheels. — Wiper wheels are cams which give a quick motion to mechanism, the most com- mon 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 pro- jecting points may be employed. Cam Sectors. — Fig. 94 shows a type of cam CAMS AND ECCENTRICS 175 which is designed for rock shafts. The object of this form of cam is to impart a gradually in- creasing 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 ^ig.^. Cam 6eetor. jF'ig. 93. Groofod Cam . J^lg. <96. Tiecwocai/^/hoiwn . 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. Cylinder Cam. — Fig. 95 shows one form of cylinder A with a groove B in it, which serves 176 MOTOES FOR BOYS 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 sinuons groove F to reciprocate a bar G to and fro, the groove being either regular, so as to give a continuous back and forth move- T^ig. 97. Pi votedi T^ollourer for Cam . ment of the bar ; or adapted to give an irregular motion to the bar. 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 rest- ing on the cam D. The arm A has also a right-angled arm E ex- tending downwardly, and is kept in contact with CAMS AND ECCENTRICS 177 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 ec- centric may be a cam, but a cam is not always ec- Fig98£ccen/ric[ ^ I J^ig. 99. J57cce?ttric Cam . centric in its shape. The term is one in direct contrast with the word eccentric. 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 178 MOTORS FOE BOYS 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 mo- 2^.100. T 7 na?wu2a77y - rorm£d, JZccenfofc . tion, and a slight stop only, at the half turn, and the return is then as sudden as the motion in the other direction. CHAPTER XII GEARS AND GEARING For the purpose of showing how motion may be converted from a straight line or from a cir- cular 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 sug- gestions for other forms. Racks and Pinions. — The rack and pinion is the most universal piece of mechanism for changing 179 180 MOTOKS FOR BOYS motion. Fig. 101 illustrates it in its most sim- ple form. When constructed in the manner shown in this figure it is necessary that the shaft which carries the pinion shall have a rocking mo- tion, or the rack itself must reciprocate in order to impart a rocking motion to the shaft. Fig. J 01 RackandTinwn . TYg. JO 2. Rack * 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 dis- tances 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 man- gle rack is resorted to where a back and forth, or GEAES AND GEARING 181 a reciprocating movement is to be imparted to an element by a continuous rotary motion. The plain mangle racks are shown in Figs. 103 and 104, the former of which has teeth on the in- side of the opposite parallel limbs, and the latter, IPig. 703. Main Tnan gle Hack . JTzgJM. ?7Za,?ig lo RcLo7cMoito?t . J^tg. ?05. e/HtzTnctte, Ci7 -cula7 ' Tftotion. 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 dur- 182 MOTOES FOR BOYS ing 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 T^g. f06. Conirolli7ig Pinion forTftcwgfoRacfc pinion in engagement with the teeth of the mangle rack. One such method is shown in Fig. 106. 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 Gr. 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 GEAES AND GEARING 183 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 dif- ferent positions 1, 2, 3, etc., which correspond with the positions on the circle D. The Deax> Centers. — There is also another ad- / k, 8 **p $ 6 76 1 £ 6 <4 5 6 76 -T 7 "^. 70Z Illu6J7'ati?ig C?an/c-p in fooi/ement r vantage which the rack possesses. Where re- ciprocating motion is converted into circular mo- tion, 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 direc- tion 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 184 MOTORS FOR BOYS from H to Gr, the cylinder does fully four-fifths of the work of the engine. While the crank is turning from Gr to D, or JTlp. /OS. Fhe Dead Cento : 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 in- stead of the crank it would add greatly to the ef- fectiveness of the steam used in the cylinder. T^ig. 709. Ciank Tflotwn -Suddtifafe. Crank Motion Substitute. — In Fig. 109 the pinion A is mounted so that its shaft is in a verti- GEAES AND GEARING 185 cal slot B in a frame C. The mangle rack D, in this case, has teeth on its onter 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. Mangle Wheels. — The form which is the most universal in its application is what is called the CO-*? a T^ig. //O. faanale Wheel . mangle wheel. In Fig. 110 is shown a type wherein the motion in both directions is uniform. Mangle wheels take their names from the iron- ing 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 ma- chines. In some mangles the work between the rollers is uniform back and forth. In others the 186 MOTORS FOR BOYS 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 jf^Yg. ///. Quick Tietum ?/iotio?i . forth the production of many forms of wheels, some of them very ingenious. 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 out- line, one portion of the slot being concentric with the shaft 0. 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. GEAES AND GEAEING 187 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. Ill, which has a pair of curved parallel slots, with teeth surrounding -i^^ //£. zrfccete? cited, Circular footion. the slots. When the wheel turns nearly the en- tire revolution, with the pinion in contact with the outer set of teeth, the movement transmitted to the mangle wheel is a slow one. 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 188 MOTORS FOR BOYS 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 JFfy //S. Quick Jjetura Gearing . shaft is feathered, as shown at E, so that it will carry the gear along from end to end. 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 for- GEAES AND GEARING 189 ward speed and a quick return action, is illus- trated 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, 7^//^. derail Gearin p. 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. 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 190 MOTORS FOR BOYS 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 begin- ning 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 de- pend 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 con- dition 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 191 192 MOTORS FOR BOYS 10,500 degrees of heat, but it is well known that heat extends over a much higher range. Assuming, however, that the figures given rep- resent the limit, it will be seen that the difference between ice and boiling water, namely, 180 de- grees, is a very small range compared with the temperatures referred to. In order to effect this change power is neces- sary, 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 re- ceiver 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 con- verted into steam, and is permitted to exhaust into the receiver. When all the water is con- verted into steam and fills the receiver we shall have the same pressure inside the receiver as on the outside. SPECIAL TYPES OF ENGINES 193 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 pres- sure indicates the presence of heat; and when- ever 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 fur- ther. 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 at- mospheres 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 194 MOTORS FOR BOYS greater than that of the receiver, grows colder, due to the rarefied gases within. Now bearing in mind the previous statement, that loss of pres- sure 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 permit- ting it to exhaust into a space which rarefies it, will make a lower temperature. It is this principle which is used in all re- frigerating machines, whereby the cool pipes ex- tract the heat from the surrounding atmosphere, or when making ice, from the water itself, and this temperature may be lowered to any extent de- sired, dependent on the degree of rarefaction pro- duced. Let us now see how this applies to the genera- tion of power in which we are more particularly interested. All liquids do not evaporate at the same tem- perature 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 SPECIAL TYPES OF ENGINES 195 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-car- bon, 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 com- bustion motor. The problem is a complicated one for the fol- lowing 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. Sec- ond, the apparent impossibility of properly pack- 196 MOTOKS FOR BOYS ing 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. JT r ig.//& &impfcjRofaryttzgzne. In Fig. 115 is shown a type of rotary which is a fair sample of the characteristics of all mo- tors of this form. It comprises an outer cylin- drical 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 SPECIAL TYPES OF ENGINES 197 dimensions that it is m contact with the shell at its upper side only, as shown at D, leaving a chan- nel 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 Gr, 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-dis- posed 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, 198 MOTORS FOR BOYS in a housing outside of the circular path F, be- tween 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 op- positely-projecting rigid blades I. When steam J^ff* //6. 7?ouHe feed Ttotiztyttigine. enters either of the stfpply 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. Cajloric Engine. — This is an engine which is dependent on its action upon the elastic force of SPECIAL TYPES OF ENGINES 199 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 con- tacts 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 200 MOTORS FOR BOYS rotation, and develops a wonderful amount of power. It will be understood that the disks are en- closed by a suitable casing, so that the steam is carried around and discharged at a point about three quarters of the distance in the circumfer- ence. 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 possibili- ties. 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 expan- SPECIAL TYPES OF ENGINES 201 sive 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 prog- ress 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 con- struction 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. — Educa- tion, the cultivation of the fine arts, and the desire for luxuries, without the capacity for quickly in- terchanging commodities and to intermingle with 202 DEVELOPMENT OF HUMAN RACE 203 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 re- garded 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 scat- tered peoples. 204 MOTORS FOR BOYS 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 inter- est 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 mo- tive power, changed the whole philosophy of his- tory 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 pop- ularly 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 im- mediate cause, but it was the direct cause which prevented the building of railroads between the two sections. It simply reenforces the argument that the mo- tor, the great power of enginery, was not brought into play to unite people who were antagonistic, and who could not, due to imperfect communica- tion, understand each other. To-day the United States contains an area DEVELOPMENT OF HUMAN RACE 205 nearly as great as the whole of Europe, including Russia, with their twenty, or more, different gov- ernments. 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 un- like in their characteristics. It has been shown that wherever this is the case it is due to lack of quick and cheap intercommuni- cation. 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, not- withstanding 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 stabil- ity 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. 206 MOTORS FOE BOYS 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 con- trolled 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 at- tractive to the boy, but the mastery of the sub- DEVELOPMENT OF HUMAN EACE 207 ject 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 op- portunities 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 ENEKGY OF THE SUN, AND HOW HEAT IS MEASTJKED 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 princi- ples 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 am'ount 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 crank-shaft. Fourth, radiation, the dissipation of heat, and condensation, are always at work, and thus de- tract from the efficiency of the engine. 208 THE ENEEGY OF THE SUN 209 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, in- volves 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 con- tinously over every thirty square feet of the sur- face of our globe. 210 MOTORS FOR BOYS 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 cov- ered 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, how- ever, subject to the same drawbacks that are urged against the lens, namely, that the heat is irregu- lar, and open to great variations. THE ENERGY OF THE SUN 211 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 in- stance, 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 gen- ius, and millions would not be sufficient to com- pensate the fortunate one who should be able 212 MOTORS FOE BOYS to dispense with three of the steps set forth. The Measukement 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 ex- pressed. 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 subtile, imponderable and pervading every- thing. 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 THE ENERGY OF THE SUN 213 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 re- garded 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 ac- celerated, 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 Centi- grade 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 re- 214 MOTOES FOR BOYS quired 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 en- gineering unit is what is called the British Ther- mal Unit, and designated in all hooks 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 3'4,500 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 con- duction, convection, or radiation. THE ENERGY OF THE SUN 215 Conduction is the method whereby heat is trans- mitted 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 stand- ard, 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 be- gins 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 216 MOTOES FOR BOYS 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. Amplitude. Absorbent. Absorbing. Absorption. Abutment. Accuracy. Accession. Accelerate. Accessible. Accelerated. Actuating. Advance Spark. Aeration. Alkali. Allusion. Anomaly. Adhesion. Adjustment. Independent; free from all limitations. Greatness of extent; the state or quality of being sufficient. A material which will take up a liquid. Taking up, or taking in. The act or process of taking up or fully occupying. A wall; a stop. Correctness ; positiveness. Added to; addition, or increase. Quickened; hurried. Available; capable of being reached. A quickening, as of process or action. Moved or incited by some motive. 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. To add air; to impregnate with oxygen. In chemistry it is known as a compound of hydro- gen and oxygen, with certain chemicals. Anything which will neutralize an acid. Referring to; noticed. A deviation from an ordinary rule; irregular. To cling to; to stick together. To arrange in proper order; to set into working con- dition. 217 218 GLOSSARY Alternating current. Ampere. Amplitude. Analysis. Annular. Armature. Assuming. Asphaltum. Atmospheric. Available. A current which goes back and forth in opposite di- rections; unlike a direct current which flows con- tinuously in one direction. The unit of current; the term in which strength of cur- rent is measured. An ampere is an electro-motive force of one volt through a resistance of one ohm. The state or quality of being broad, or full. The separation into its primitive or original parts. Pertaining to or formed like a ring. The part of a dynamo or motor which revolves, and on which the wire coils are wound. Taking on ; considered to be correct or otherwise. A bituminous composition used for pavements, prop- erly made from natural bitumen, or from asphalt rock. Referring to; noticed. Capable of being employed or used. Bearings. Bifurcated. Blow-off valve. Bombard. Bonnet. Butterfly- valve. Caloric. Cam. The part in mechanism in which journals or spindles rest and turn. In two parts; branching, like a fork. A valve so arranged that at certain pressures the valve will automatically open and allow the steam to escape from the boiler. An assault; an attack by shot or shell. The cap of a valve, which is so arranged that while it permits the valve stem to turn, will also prevent leakage. A form of valve which is usually flat, and adapted to open out, or turn within the throat or pipe. Pertaining to heat. A rotating wheel, or piece, either regular or irregu- lar, non-circular, or eccentric. GLOSSAKY 219 Carbon. Carbureter. Carbonized. Carbureted. Centripetal. Centrifugal. Check valve. Chemical. Chambered. Circumfer- ence. Circularly. Circulation. Clearance. Classification. Coincide. Cohesion. Cooperate. Compounding-. A material like coke, ground or crushed. It re- quired high heat to burn it, and it is used for the burning material in electric arc lamps. The device used to mix air and gaseous fuel in an internal combustion engine. Put into a charred form; coke is carbonized coal; charcoal is carbonized wood. Air or gas to which has been added the gaseous product of petroleumi, or 'some distillate. That which draws inwardly, or to the center, like the gravitational action of the earth. That which throws outwardly; the opposite of cen- tripetal. A form of valve which will permit liquids to freely flow in one direction, but which will open automat- ically, so as to allow the liquid to flow in the op- posite direction. Pertaining to the composition of matter; or relat- ing to chemistry. Having compartments, or divided up into recesses. Around the outside. Around; about the circumference. The movement of water to and fro through conduits. The space at the head of a cylinder within which the steam or gases are compressed by the piston. To put in order in a systematic way. To correspond with identity of parts. To stick together. The attraction of material sub- stances of the same kind for each other. To work together harmoniously. Composed of or produced by the union of two or more parts, or elements. 220 GLOSSARY Complicated. Commutator. Combustion. Concaved. Condensation. Condenser. Concentric. Conductor. Conically. Conduit. Conduction. Constant. Conserve. Commodity. Connecting Rod. Contrivance. Contradis- tinction. Cornish. Contact Breaker. Very much involved; not simple. 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. Burning; the action of the unity of oxygen with any substance, which causes it to be destroyed or changed. Hollowed. The change from a gaseous to a liquid or solid state. An apparatus which converts a gas into a liquid. A line which at any point is at the same distance from a common center. A substance which will convey either heat or electric- ity from one end to the other. In the form of a cone. A trough, tube, or other contrivance, which will con- vey liquids or gases from place to place. The capacity to transmit from one point to another. Being the same thing at all times ; not varying. To take care of; to use judiciously. Any product, or kind of goods. That part of mechanism which connects the piston rod with the crank. Any mechanism, or device which will serve a certain purpose. That which is opposite to, comparatively; taken in conjunction with for the purpose of comparison. A form of boiler which has the fire tubes within the water space. A device which has the current normally in circuit, and is so arranged that the circuit is broken at GLOSSARY 221 certain intervals, and again immediately reestab- lished. Co-relate. Belonging to; having reference to the same order. Conventional. The regular manner or method. Contact A device for making contacts in an electric circuit Maker. at regular intervals. Convolution. The turns or twists taken. The changes or move- ment 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 1 . Changing; to put in an opposite condition. Conical. In the form of a cone. Cylindrical. In the form of a cylinder; barrel-shaped. Cyclopedia. A work which gives, in alphabetical order, the ex- planations 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. Deenergize. To take power away from. Deflecting. To glance off; to change the regular or orderly course. Demagne- To take magnetism away from. tized. Deteriora- To take away from; to grow smaller; to lessen; to tion. 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. Diametric- Across or through the object; through the center, ally. 222 GLOSSARY Dioxide. An oxide containing two atoms of oxygen to the molecule. Direct ctir- An electric current which flows continuously in one rent. direction. Dissipated. Changed, or entirely dispensed with; usually ap- plied 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 cen- ter 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 pro- duces great energy. Electrolyte. The agent, or material in a battery, usually a liquid, GLOSSARY 223 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 employ- ment of any kind. Emission. To send out from; a sending or puttting 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 under- stood. 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 ther- mometer 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 influ- ence 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 224 GLOSSARY in moving one pound through a distance of one foot. Four-cycle. A gasoline engine, in which the ignition of the com- pressed 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 direc- tion. Friction. A retarding motion; the prevention of a free move- ment. Function. The qualities belonging to an article, machine or thing; that which a person is capable of perform- ing. Fundamental. The basis; the groundwork of a thing. Gaseous. Of the nature of a gas. Gearing 1 . Usually applied to two or more sets of toothed wheels which cooperate with each other. Generating 1 . Producing; manufacturing; bringing out of. Globules. The small particles of liquids; or the molecules com- prising 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 Ten- A term applied t6 a current of electricity, which has sion. 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-car- A gas made from the vaporization of crude petro- bon. leum or of its distillates. GLOSSARY 225 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; determina- tion to act in a certain way through some influence. Impinge. To strike against; usually to contact with, at an angle. Incompar- Too good or great to measure, able. 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 con- duct 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. 226 GLOSSAEY Interrupted. Interstices. Instantane- ous. Intricate. Inquisitive. Jacketing. Jump Spark. Kinetic. Latent. Lateral. Lines of force. Low Tension. Lubrication. Mangle. Magneto. Magnetism. Manifesta- tion. Make and Break. Manifold. To stop; to take advantage of. The spaces in between. Immediately; at once; without waiting. Difficult; not easy. The desire to inquire into. To coat or cover on the outside. 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. Consisting in or depending on motion. That which is within itself. Branching out from the sides; usually applied as the meaning for the direction which is at right angles to a fore and aft direction. Applied to electricity, air, water, or any moving ele- ment, which has a well directed movement in a definite direction. In methods for igniting hydro-carbon charges, any circuiting which has a low voltage. The oiling of mechanical parts to reduce friction. A machine for smoothing out clothing, goods, etc. A dynamo which has the field pieces, or poles made of permanent magnets. That quality, or agency by virtue of which certain bodies are productive of magnetic force. Showing or explaining a state of things; an out- ward show. An ignition system, which provides for throwing in and cutting out an electric circuit. A system of piping whereby the exhausts of a gaso- GLOSSARY 227 Manganese. Manually. Material. Mechanically, Mobility. Multiple. Neutral. Normal. Ohm's law. Oscillating:. Orifice. Organism. Oxidation. Oxygen. line engine are brought together into one common discharge. A hard, brittle, grayish white metallic element, used in the manufacture of paints and of glass, and also for alloying metals. Doing things by hand; muscular activity. Substances and parts from which articles are made. Doing things by means of machinery, or in some regular order. The capacity to move about. 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. Neither; not in favor of any party or thing. As usual; in the regular way; without varying from the ordinary manner. 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. Moving to and fro, like a pendulum. An opening; a hole. Any part of the body, or any small germ or animal- cule. The action of air or oxygen on any material, is called oxidation. Thus rust on iron is called oxi- dation. A colorless, tasteless gas, the most important in na- ture, called the acid-maker of the universe, as it 228 GLOSSARY 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 ly- ing 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 hav- ing 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, hydro- gen 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 elec- trical 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 com- mences. 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. GLOSSARY 229 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 bat- A cell, or a number of cells, made of pairs of me- tery. tallic couples, immersed in an electroly.te of either an acid or an alkali. Proney A device for testing machinery and determining Brake. power, by means of friction. Primeval. The earliest; the first; of a low order. Proportion. The relation of one thing or number, to another ; com- parative 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 tem- perature during the progress of the work. 230 GLOSSARY Requisite. Residue. Resistance. Reciprocat- ing. Refinement. Retort. Revolution. Rock Shaft. Rotation. Sal-Ammon- iac. Secondary Battery. Secondary coil. Scavenging. Sector. Secondary. Segment. The necessary part; the requirement. The balance; what is left over. Opposition; against. One for the other; moving from one side to the other. Chastity of thought, taste, manner, or actions. A vigorous answer. A receptacle adapted to stand a high heat. Turning, like the earth in its orbit. A shaft which turns part of its rotation in one di- rection, and then turns in the other direction. 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. A white metallic element. A battery which is charged with a current, and then gives forth an electric current of a definite amount. It is also known as an accumulator, since its ele- ments continue to accumulate electric energy. 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. To clean out; to scour. 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. Occupying a second place; not of the first kind, or place. A part cut off from a disk, by a single line; the part of a circle included within a chord and its arc. GLOSSAEY 231 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 Heat- To heat up beyond the ordinary or normal point, ing. Subtle. Crafty; made of light material; daintily con- structed. 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 con- nected with a fluid under pressure. Terminal. The end ; the last part. Technical. Specially or exclusively pertaining to some art or subject. Throttling. The closing of a port; the cutting down of a sup- ply- Throttle A device which is designed to cut off the flow of a fluid. Valve. That which is speculative, as distinguished from prac- Theoretical. tical. 232 GLOSSAKY Transforma- tion. Transmit. Transference. Transferred. Triple. Turbine. Tubular. Two-Cycle. Typical. "Undershot. Unison. Universally. Utility. Vacuum. Vaporizing. Variable. Venturi Tube. Vertical. Vibrator Coil. A complete change; made over into something else. To convey; to send to another part. To convey to another part; the change from one thing to another. Put over. Three; thrice. To turn; a form of water wheel and steam engine, where the fluid impinges against the blades ar- ranged around the perimeter of the wheel. Hollowed; like a pipe. A gasoline engine, in which the compressed hydro- carbon gases are fired every turn of the crank shaft. The nature or characteristics of a type. A type of wheel in which the water shoots past and against the blades on the lower side. Together; conjointly; acting with each other. All over the world; throughout all space. Use; that which is valuable or of service. That part from which all material is taken; in a limited sense, air, which has less density than the normal. To convert into gas, usually by heat. With differing characteristics; changeable. A form of tube which has a contracted part between its ends. In the direction of a line which points to the center of the earth. 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. GLOSSARY 233 Volt. Voltage. Volt Meter. Watt. Weight. Winnowed. Wiping Bar. The pressure of an electric current ; the unit of elec- tromotive force. Electromotive force as expressed in volts. An instrument for indicating the voltage of an elec- tric circuit. The electrical unit of the rate of working in an elec- tric circuit, the rate being the electromotive force of one volt, and the intensity of one ampere. The measure of the force toward the center of the earth, due to gravity. Taken out; sifted from. 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. §? 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 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 THE „ MOTOR BOVS O0UDS 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 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 12mo. By LESTER CHADWICK Author of "The College Sports Series" Illustrated. Price per volume, 60 cents, postpaid. Ever since the success of Mr. Chadwick's "College Sports Series" we have been urged to get him to write a series dealing exclu- sively 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 hi6 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 Uni- versity. 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 ms a Professional Pitcher In this volume the scene of action is shifted from Yale Col- lege 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. 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 stand- still, 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 risk 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 12mo. By MARGARET PENROSE Author of "The Motor Girls Series" Illustrated. Price per volume, 60 cents, postpaid. Dorothy Dale: A Girl of To-Day Dorothy is the daughter of an old Civil War veteran who is running a weekly news- paper in a small Eastern town. When her ^l EfflM*. ^a f atner 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 Tangle- wood 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 12mo. By MARGARET PENROSE Author of the highly successful "Dorothy Dale Series" Illustrated. Price per volume, 60 cents, postpaid. The Motor Girls or A Mystery of the Rood When Cora Kimball got her touring ear 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 vol- ume. 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 Girl9 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. a 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 encamp- ment, 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. 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 Hydroplane His 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 Speed- well boys. They are clean cut and loyal lads. 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 Deacidified using the Bookkeeper process. Neutralizing agent: Magnesium Oxide Treatment Date: June 2004 PreservationTechnologies A WORLD LEADER IN PAPER PRESERVATION 1 1 1 Thomson Park Drive Cranberry Township, PA 16066 (724)779-2111 LIBRARY OF CONGRESS 012 352 649 1 4 J