Motors

Front matter

EVERY BOY'S MECHANICAL LIBRARY

Every Boy's

Mechanical

Chapter I. Motors and Motive Power 5-21

The Water Fall. Water moves in One Direction only. What is Energy. Stored or Potential Energy. Kinetic Energy. Friction. Resistance. Inertia. The Law of Bodies. Internal and External Resistance. Momentum. Energy Indestructible. Wind Power. Rectilinear Motion. Oscillating Motion. Movements in Nature. How Man Utilizes the Various Movements. Kinds of Potential Energy. The Power in Heat. Energy in Steam. Energy from the Sun. Power from Water. The Turbine. Calculating Power of a Turbine. Horse Power. Foot Pounds. Power and Time. Gravitation. Utilizing the pull of Gravity. Taking Advantages of Forces. Pitting Forces Against each Other. Centripetal and Centrifugal Forces. Power not Created. Developing the Power of Motors. Experimenting.

Chapter II. The Steam Generator 22-31

Water as an 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. Importance of the Valve. Expanding the Steam. Balanced Valve. Rotary Valve. Engine Accessories. Efficiency of Engines. How Steam acts in a Cylinder. Indicating the Engine. Mean Efficiency. Calculating Horse Power. Condensation. Atmospheric Pressure.

CONTENTS

PAGE

The Condenser. Pre-heating. Superheaters. Compounding. Triple and Quadruple Expansion Engines. The Steam Turbine. Pressure and Velocity. Form of Blades. Compounding the Jet.

Chapter IV. Fuels and Combustion 60-67

Solid Fuels. Liquid Fuels. Combustion. Oxidation. The Hydro-Carbon Gases. Oxygen and the Atmosphere. Internal Combustion. Vaporizing Fuel. Explosion by Heat Compression. How Compression Heats. Elasticity of Gases. Advantages of Compression. The Necessity of Compression.

Chapter V. The Internal Combustion Engine . . 68-82

Fixed Gases. Gas Engines. Energy of Carbon and Hydrogen. The Two-Cycle Type. Advantages of the Two-Cycle Engine. The Four-Cycle Engine. The Four Cycles. Ignition Point. Advantages of the Four- Cycle Type. The Loss in Power. Engine Construction. Valve Grinding. The Crank Shaft. The Cams.

Chapter VI. Carbureters 83-101

Functions of a Carbureter. Rich Mixtures. Lean Mixtures. Types of Carbureters. The Sprayer. The Surface Type. Governing a Carbureter. Primary Air. Needle Valve. Secondary Air. Requirements in a Carbureter. Size of a Carbureter. Rule for Size of Carbureters. The Throttle. Flooding. Adjustability. Surface Carbureters. Float Chamber.

Chapter VII. Ignition. Low Tension System . 102-120

Electricity. Magnetism. The Armature. Characteristics of Electricity. Make and Break System. Voltage. High and Low Voltage. Low Tension method. Disadvantages of Make and Break. Amperes. Resistance. Direct Current. Alternating Current. Induction. Generating Electricity. Primary Battery. Making a Dry Cell. Energy in a cell. Wiring Methods. Series Connection. Multiple Connection. Series Multiple. Watts. Testing a Cell. Testing with Instruments. Simple Battery Make and Brake System. To Advance the Spark. The Magneto in the Circuit. Magneto Spark Plug.

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 Condenser. Operations of a Vibrator Coil. The Distributor. Circuiting with Distributor.

Chapter IX. Mechanical Devices Utilized in Power 141-157

The Unit of Time. Horse Power. Proney Brake. Reversing Mechanism. Double Eccentric Reversing Gear. Balanced Slide Valve. Balanced Throttle Valve. Engine Governors. Injectors. Feed Water Heaters.

Chapter X. Valves and Valve Fittings .... 158-171

Check Valve. Gate Valve. Globe Valve. The Corliss Valve. Corliss Valve-operating Mechanism. Angle Valve. Rotary Valves. Rotable Engine Valves. Throttle Valves. Blow-off Valves. Pop- Safety Valves.

Chapter 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 Engines. Adhesion Engines.

Chapter XIV. Enginery in the Development of the Human Race 202-207

Power in Transportation. Power vs. Education and the Arts. Lack of Power in the Ancient World. The Early Days of the Republic. Lack of 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 Automobile. High Character of Motor Study. The Unlimited Field of Power.

Chapter XV. The Energy of the Sun, and How Heat

is Measured 208-216

Fuel Economy. Direct Conversion. The Measurement of Heat. Caloric. Material Theory. Heat Transmitted in Three Ways. Conduction. Convection. Radiation.

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

The motor is the great dominating factor in the world of industry. Every wheel and spindle; every shaft and loom, and every piece of mechanism which has motion, derives it from some sort of motor.

The term motor has a wider significance than any other word. A steam engine is a motor, and so, also, is a dynamo, a water wheel or a wind mill.

It would be just as descriptive to call a wind mill a wind motor, or a steam engine a steam motor, as to adhere to the old terms ; and, on the other hand, since it would be out of place to call a dynamo or a wind mill an engine, the word motor seems best adapted to express the meaning of every type of mechanism which transforms energy into motion.

In considering the subject I shall proceed on the theory that the boy knows nothing whatsoever of the subject, nor the terms used to designate the various phases, subjects and elements. It must be elementary in its character, and wholly devoid

of technical terms or sentences.

While it is necessary to give information in a book of this character, on the methods for figuring out power, it must be done without resorting to the formulas usually employed in engineering works, as they are of such a nature that the boy must have some knowledge of the higher mathematics to follow out the calculations employed.

Indeed, every phase should be brought within the mental view of the boy, and to do this may occasionally necessitate what might appear to be long drawn out explanations, all of which, it is hoped, will be the means of more clearly presenting the subject.

The opening chapters, which treat of the fundamentals, will be as nearly complete as possible, and thus lay a foundation for the work we shall be called upon to perform, when we treat of the structures of the different parts and devices in the various types of motors.

The object is to explain power in its various phases, how derived, and the manner in which advantage is taken of the elements, and substances with which we are brought into contact. The reasons for each step are plainly set forth with the view of teaching the boy what power means, rather than to instruct him how to make some particular part of the machinery.

The Inquisitive Trait. — My experience has impressed me with the universality of one trait in boys, namely, that of inquisitiveness. Put a machine before a boy and allow him to dissect it, and his curiosity will prompt him to question the motive for the particular construction of each part of its make-up.

The Reasons for Doing Things. — He is interested in knowing the reason why. Every boy has the spirit of the true investigator, — that quality which seeks to go behind or delve down deeply. This is a natural instinct.

The Mystery of Mechanism. — If this taste is gratified, and he thereby learns the mystery of the machine, what a wonderful world is opened to him! The value of the lesson will depend, in a large measure, on the things which he has found out for himself. It is that which counts, because he never forgets that which he has dug out and discovered.

Curiosity Which Prompts Investigation. — I recall a farmer's boy whose curiosity led him to investigate the binding mechanism of a reaper. It was a marvel to him, as it has been to many others. He studied it day after day, and finally, unaided mastered the art. That was something which could not be taken away from him.

It was a pleasure to hear him explain its operation to a group of boys, and men, too, in which he used the knot itself to explain how the various fingers and levers 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 knowledge which has been gained by others, so as to enable the boy to go forward from that point, and thus gain immensely in time.

There is so much that has been developed in the past, with reference to the properties of matter, or concerning the utility of movements, and facts in the realm of weights, measures, and values of elements which he must deal with, that, as he studies the mechanical problems, the book becomes a sort of cyclopedia, more than a work designed to guide him in the building of special engines or motors.

The Author.

MOTORS

Chapter I

What makes the wheels turn round! This simple question is asked over and over again. To reply means pages of answers and volumes of explanations.

The Water Fall. — Go with me to the little stream I have in mind, and stand on the crest of the hill where we can see the water pouring down over the falls, and watch it whirling away over the rocks below.

The world was very, very old, before man thought of using the water of the falls, or the rushing stream below, to grind his corn or to render him other service.

Water Moves in One Direction Only. — What the original man saw was a body of water moving in one direction only. When he wanted to grind corn he put it in the hollow of a rock, and then beat it with a stone, which he raised by hand at each stroke. In doing so two motions were required in opposite directions, and it took thousands of years for him to learn that the water rushing along in one direction, could be made to move the stone, or the pestle of his primitive grinding mill, in two directions.

It took him thousands of years more to learn another thing, namely, that the water could be made to turn the stone round, or rotate it, and thus cause one stone, when turning on another, to crush and grind the grain between them.

Now, as we go along with the unfolding of the great question of motors, we must learn something of the terms which are employed, to designate the different things we shall deal with, and we ought to have some understanding of the sources of power.

What Is Energy? — The running, as well as the falling water represent energy. This is something which is in the thing, the element, or the substance itself. It does not come from without. It is not imparted to it by anything.

Stored or Potential Energy. — At the top of the falls, look at that immense rock. It has been there for centuries. It, also, has energy. There is stored within it a tremendous power. You smile! Yes, the power has been there for ages, and now by a slight push it is sent crashing down the precipice. The power developed by that fall was thousands of times greater than the push which dislodged it.

But, you say, the push against the stone represented an external force, and such being the case, why do you say that power is within the thing itself! The answer is, that not one iota of the power required to push the stone off its seat was added to the power of the stone when it fell. Furthermore, the power required to dislodge the stone came from within me, and not from any outside source.

Here we have two different forms of energy, but both represent a moving force. The power derived from them is the same.

Kinetic Energy. — The energy of the falling water or stone is called Kinetic energy. In both cases the power developed came from within themselves and not from any exterior source.

The difference between Potential and Kinetic Energy is therefore that Potential Energy represents the capacity to do work, while Kinetic Energy is the actual performance of work.

Friction. — In every form of energy there is always something to detract from it or take away a portion of its full force, called friction. When a shaft turns, it rubs against the bearings, and more or less power is absorbed.

When a wheel travels over the ground friction is ever present. The dislodging of the stone required ten pounds of energy, but a thousand pounds was developed by the fall. The water rushing along its rocky bed has friction all along its path.

Resistance. — This friction is a resistance to the movement of a body, and is ever present. It is necessary to go back and examine the reason for this. As long as the stone was poised at the top of the precipice it had latent or potential energy, which might be termed power at rest. When it fell it had power in motion. In both cases gravity acted upon the stone, and in like manner on the water pouring over the falls.

Inertia. — Inertia or momentum is inherent in all things and represents the resistance of any body or matter, to change its condition of rest or standing still into motion, and is then called Inertia of Rest, or the resistance it offers to increase or decrease its speed when moving, and is then called Inertia of Motion.

Inertia or momentum is composed by the weight of the body and its speed and is measured by multiplying its weight by its speed.

The law is, that when a body is at rest it will remain at rest eternally, and when in motion it will continue in motion forever, unless acted on

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 resisting internal force, but when the stone was moving through the air, the friction with the air created external resistance.

Energy Indestructible. — There is another thing which should be understood, and that is the absolute indestructibility of energy. Matter may be changed in form, or in the direction of its motion, by the change of kinetic into potential energy, or vice versa, but the sum total of the energy in the world is unalterable or constant.

The tremendous power developed by the stone when it plunged through space and struck the rocks below, developed a heat at its impact. Thus the moving force which was a motion in one direction was converted into another form of energy, heat. The expansion of the material exposed to the heat also represented energy.

When powder explodes and absolutely changes the form of the substance, its volume of expansion, if it should be retained within a vessel, would perform a certain amount of work, and the energy is thus transferred from one form to another without ceasing.

Wind Power. — Primitive man also saw and felt the winds. He noted its tremendous power, but he could not see how a force moving in one direction only could be utilized by him.

Rectilinear Motion. — This movement of the wind in one direction, like the water flowing along the bed of the river, is called rectilinear motion. It required invention to convert rectilinear into circular motion.

Oscillating Motion. — When he threshed his grain and winnowed it by shaking it to and fro, to rid it of the 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 movement was brought about.

Movements in Nature. — All movements in nature are simple ones, of which the following are illustrations :

1. Rectilinear., which, as stated, means in a straight line.

2. Circular, like the motion of the earth on its axis, once every twenty-four hours.

3. Oscillatory, like a to and fro movement, the swaying branches of trees, or the swinging of a pendulum.

How Man Utilizes the Various Movements. — What man has done is to utilize the great natural forces in nature in such a way as to produce these movements at will, in either direction, with greater or less speed, at regular or irregular intervals, and at such amplitudes as are required to perform the necessary work.

Kinds of Potential Eneegy. — Now, materials have within themselves potential energy of various kinds. Thus, powder, if ignited, will burn, and in burning will expand, or explode, as we term it. This is true also of oils and gases. The expansion pressure produced from such substances depends on the speed at which they will burn, and in so confining the burning substances that a great pressure is produced.

The Power in Heat. — The pressure of all such substances against the confining medium depends on heat. Any gas which has 523 degrees of heat imparted to it will expand double its volume. If

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 additional, it will occupy over 3400 cubic inches of space. It will thus be seen why steam, gas, and gasoline engines are called heat engines, or heat motors.

Energy From the Sun. — Many attempts have been made to utilize the heat of the sun, to turn machinery, but the difficulty has been to secure sufficient heat, on the one hand, and on the other to properly cool down the heated gases, so that the various liquid and solid fuels are required to make the heat transformations.

Power From Water. — In the use of water two forms are available, one where the water is moving along or falling in a constant open stream; and the other where the flowing water is confined and where its flow can be regulated and controlled. The latter is more available for two reasons :

First: Economy in the use of water.

Second : Ability to control the speed or movement of the motor.

With running or falling streams a large surface is required, and the wheels turn slowly. Two wellrecognized 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.

In both types it is difficult to so arrange them as to shut off the power or water pressure when required, or to regulate the speed.

The Turbine. — Wheels which depend on the controllable pressure of the water are of the turbine type. The word is derived from the Latin word turbo, meaning to whirl, like a top. This is a type of wheel mounted on the lower end of a vertical or horizontal shaft, within, or at the bottom, of a penstock. The perimeter of the wheel has blades, and the whole is enclosed within a drum, so that water from the penstock will rush through

the tangentially-formed conduit into the drum, and strike the blades of the wheel.

A column of water one inch square and twentyeight inches high weighs one pound, — or, to express it in another way, the pressure at the bottorn 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 itself from the wheel casing.

Let us assume that the diameter of the wheel at the center of the blades is two feet, which would, roughly estimating, give a circumference of six feet, or a travel of each particular blade that distance at each turn of the wheel.

If the wheel turns one hundred times a minute, and this is multiplied by the circumference of the wheel (six feet), the result is 600 feet. This, again, multiplied by 432 pounds (which represents the pressure of the water on the entire discharge opening) , and we have a product of 259,200, which represents foot pounds.

This means the same work as if 259,200 pounds would have been lifted through a space of one foot in one minute of time. To ascertain how much power has been developed we must know how many foot pounds there are in a horse power.

Horse Power. — It is determined in this way: any force which is capable of raising 550 pounds one foot in one second of time, is developing one horse power. A man might have sufficient strength to raise such a weight once, twice, or a dozen times in succession, but if he should try to do it sixty times a minute he would find it a trying, if not impossible task.

Foot Pounds. — If he should be able to lift 550 pounds sixty times within a minute, he would have lifted 33,000 pounds one foot in one minute of time (550 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 the main factor, 33,000 pounds, and this multiplied by one foot, the result will be 33,000 foot pounds, — that is, one horse power.

It would be just the same, however, if it were possible to raise one pound 550 times in one second, or one pound 33,000 times within a minute.

Power and Time. — You are thus brought face to face with another thing which is just as important, namely, that, in considering power, time, as well as energy, must be considered. If a man, by superior strength, could be able to raise 550 pounds once within a second, then skip a few seconds, take another hold, and again raise it that distance, he would not be developing one horse power for a minute, but only for one second while he lifted the weight. For the whole minute he would only develop a certain number of foot pounds, and less than 33,000 foot pounds.

If, within a minute, he succeeded in raising it one foot for six times, this would be six times 550, equal to 3,300 foot pounds, or just one-tenth of one horse power for one minute ; so time is just as important as the amount lifted at each effort.

Gravitation. — Now, let us examine power from another standpoint. Every attempt which man makes to produce motion is an effort to overcome some resistance. In many cases this is " weight or gravity. ' ' While humanity unceasingly antagonizes the force of gravity it is constantly utilizing the laws of gravitation.

Utilizing the Pull of Gravity. — The boy laboriously drags his sled to the top of the hill against gravity, and then depends on that force to carry him down. We have learned to set up one force in nature against the other. The running stream ; the moving winds ; the tides ; the expansive force of all materials under heat, are brought into play to counteract the great prevailing agency which seeks to hold everything down to mother earth.

Utilizing Forces. — The Bible says : Blessed is he who maketh two blades of grass grow where one grew before. To do that means the utilization of forces. Improved machinery is enabling man to make many blades grow where one grew before. New methods to force the plow through the soil; to dig it deeper; to fertilize it; and to harvest it; all require power.

Pitting Forces Against Each Other. — Man has discovered how to pit the forces of nature against each other, and the laws which regulate them.

Centripetal and Centrifugal Forces. — Gravity, that action which seeks to draw all matter toward the center of the earth, is termed centripetal force. But as the earth rotates on its axis another force is exerted which tends to throw substances outwardly, like dirt flying from the rim of a wheel. This is called centrifugal force.

Man utilizes this force in many ways, one of which is illustrated in the engine governor, where the revolving balls raise the arms on which they swing, and by that means the engine valve is regulated.

Power Not Created. — In taking up the study of this subject start with a correct understanding of the source of all power. It is inherent in all things. All we can do is to liberate it, or to put the various materials in such condition, that they will exert their forces for our uses. (See Page nine, " Energy Indestructible.")