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Applied Science For Metal Workers | by William H. Dooley



This book and its companion volume for the wood-working trades, first cover the general principles of science common to all industry, this material Being identical in the two books. Additional material follows this, that relating specifically to the metal trades appearing in this volume, and that relating particularly to the wood-working trades appearing in "Applied Science for Wood-Workers." The books are constructed in this way to meet the needs of particular industrial, trade, continuation, or apprentice classes where the instruction is intensive.

TitleApplied Science For Metal Workers
AuthorWilliam H. Dooley
PublisherThe Ronald Press Company
Year1919
Copyright1919, The Ronald Press Company
AmazonApplied Science For Metal Workers

By William H. Dooley, B.S., A.M.

Principal of New York Textile School; Principal Navy Yard Apprentice School under the New York City Board of Education; Formerly Principal of the Technical High School, Fall River, Mass.; Author of "Textiles," "Boot and Shoe Manufacturing," "Vocational Mathematics for Boys," "Vocational Mathematics for Girls," "Principles and Methods of Industrial Education."

Man is weak of himself and of small stature. He stands on a basis, at most for the flattest soled of half a square foot insecurely enough, nevertheless he can use tools, can devise tools. With these the granite mountains melt into light dust before him; he kneads glowing iron as if it were soft paste; seas are his smooth highways; wind and fire his unwearying steeds. Nowhere do you find him without tools; without tools he is nothing; with tools he is all. - Thomas Carlyle.

-Preface
This book and its companion volume for the wood-working trades, first cover the general principles of science common to all industry, this material Being identical in the two books. Additional materia...
-Suggestions To Teachers
The arrangement of this book is such that it may be used equally well by science teachers in the regular secondary and technical schools and by science teachers in vocational schools. When used in con...
-3. Properties Of Matter
Materials used in industry are generally defined and described according to their physical and chemical properties or characteristics. For most purposes the chemical properties are not so important as...
-4. Cohesion, Adhesion, And Inertia
The particles of matter in solids and liquids are held together by a force called cohesion. This cohesive force is stronger in some bodies than in others. Sometimes the word tenacity is used instead o...
-5. Elasticity And Ductility
When a carpenter bends the blade of his saw and releases it, the saw blade tends to return to its original position. This property is called elasticity. A substance is said to be ductile when it ca...
-6. Brittleness And Toughness
When a substance breaks easily under strain it is said to be brittle. Glass furnishes a good example of a particularly brittle substance. Toughness, on the other hand, is that property which enable...
-7. Malleability And Compressibility
A malleable substance is one which can be rolled or hammered into sheets without breaking or cracking. Gold and silver both possess a high degree of malleability. When the particles of a substance ...
-8. Porosity, Durability, And Infusibility
Every body of matter is composed of very fine particles that fill the space occupied by the body. The particles of some bodies are held more closely together than are those of others, and we express t...
-9. Indestructibility Of Matter
While all forms of matter may be changed or modified they can never be destroyed. As an illustration, when sugar dissolves in water the particles of sugar are so small or so minutely divided that they...
-Questions 1
1. Is shop practice based upon any or many sciences? 2. Is it sufficient to know only the practice of the trade to be a successful mechanic? 3. How will it assist a mechanic to know why he perfo...
-Chapter II. Weights And Measures. 10. Units Of Measure
Since not all objects have the same dimensions, it becomes necessary to have standards with which different bodies may be compared. The three fundamental units that are used in our daily experiences a...
-11. Measurement Of Distance
Distances of a few feet are usually measured with the ordinary foot rule graduated in inches, and in halves, quarters, eighths, and sixteenths of an inch. A carpenter's wooden rule is made of boxwood,...
-12. Mass And Weight
Mass is the quantity of matter contained in a body. When we speak of a pound of lead, the word pound expresses a definite quantity of matter. Commercially, weight always stands for mass. A merchant es...
-13. Density
The simplest way to determine the weight of a large body is to measure its volume and then multiply that by the weight of a unit volume of the substance. The weight of a unit volume of any substance i...
-14. Speed
The distance over which a body passes in a unit of time is called speed. Since the unit of space is usually the foot, etc., and that of time usually the minute, it follows that speed is measured in fe...
-15. Table Of Weights And Measures
The English system of weights and measures comprises the following tables which are in daily use in the shop, mill, and commercial work of America and England. Long Measure ...
-16. The Metric System
The metric system of measurement is French in origin and is largely used in Continental Europe. It is the system used by nearly all scientific workers and is finding more and more favor in this countr...
-17. Table Of Metric Measurements
The metric system of weights and measures comprises the following tables. The symbols used to express the various units of measurement in abbreviated form are also given: Measures of Le...
-18. Metric Equivalents
The equivalent of the metric units in English measurements and vice versa, carried out when necessary to several decimal places, are given below. The approximate English equivalent for the metric unit...
-19. Care In Using Right Units
In performing all calculations care is required to see that the correct units are used. Oftentimes, through haste and confusion, inches instead of being first changed into feet are multiplied by feet ...
-20. Precision Of Measurements
Mechanical problems or operations usually consist of two parts: the collecting of data, and the solving of the problem. Both of these operations require a basic knowledge of materials, considerable ju...
-21. Rules For Finding Area And Volume
The forms of most tanks, compartments, and mechanical parts are those of simple geometrical figures such as squares, rectangles, hexagons, ellipses, and circles. Every pupil should be able to find the...
-Questions 2
1. What measuring instrument is used to measure the length of a 9-ft. plate? 36-ft. boat? 20-ft. wind-shield? 2. What measuring instrument is used to measure the width of lumber? Length of bolts? S...
-Chapter III. Mechanical Principles Of Machines. 22. Why Machines Are Used
The invention of machines is the result of man's desire to save labor and to economize in the use of his own strength by utilizing, where possible, the natural forces of steam, wind, water, and electr...
-23. Tools And Machines
Tools are simple machines. When they become complicated they are called machines, and machines acting with great power take the name of engines. Workshop tools are divided into two classes, hand-to...
-24. Force And Work
To understand the principles underlying the use of tools and machines, it is necessary chiefly to understand the differences between force, work, and energy. Force is that which tends to produce, to c...
-25. Estimating The Work Done
In estimating the work done two factors are employed - distance and force (weight) - the units of which are the foot and the pound respectively. Fig. 8. - A power tool (compressed air attachme...
-26. Mechanical Principles
A tool or machine is composed of one or more of the following mechanical elements: a lever, wheel and axle, pulley, inclined plane, wedge and screw. The force exerted on the mechanical principle is ca...
-Questions 3
1. Is it possible to determine the degree of skill of a trade by the number of tools used? Explain. 2. What impression would you gather from a person who was driving carpet tacks with a machinist's...
-Chapter IV. Leverage. 27. The Principle Of The Lever
Many tools are based upon the principle of the lever. A lever is a rigid bar, straight or bent, free to turn about a point called a fulcrum. Levers are generally divided into three kinds or classes, t...
-28. Mechanical Advantage
Since a lever is a tool, its object is to assist in distributing strength or speed to the best advantage. Suppose a lever is used in moving a heavy stone. By what means can the amount of assistance re...
-29. Moment Of Forces
All problems in leverage may be solved by arithmetic and without using a model. Suppose that two weights are balanced as in Fig. 9 at the distances shown therein. As 11 times 18 equals 12 times 16 ...
-30. Levers Of The First Class
In levers of the first class, the fulcrum is placed between the acting and resisting forces as shown in Fig. 10. This figure illustrates the lifting of a heavy block by means of a crowbar and a sup...
-31. Examples Of Levers Of The First Class
Another example of a lever of the first class is the use of the fire poker with the bar of the grate serving as a fulcrum. When a lever consists of two parts fastened by a rivet, it is called a double...
-32. Levers Of The Second Class
In the second class lever the weight and force are on the same side of the fulcrum, the weight being placed between the force and the fulcrum. For example, if a mason desires to move a large piece ...
-33. Levers Of The Third Class
In the third type of lever the fulcrum is at one end, the weight at the other, and the force is placed between them (Fig. 13). The advantage of this arrangement is that a small force causes the extrem...
-34. Compound Levers
Levers are said to be compounded or compound when their free ends are joined to the free ends of other levers. Large scales used in weighing luggage, bricks, wagon loads, and so on, consist of an arra...
-35. Problems In Compound Leverage
Problems in compound leverage are easily reduced to repeated cases of simple leverage, the force at the end of the first lever being the weight or force applied to the second lever, and so on through ...
-36. Shapes Of Levers
The fulcrum of levers used in machinery is usually cylindrical in shape, made of soft metal, and supported in the interior of a cylindrical opening in which the lever works, so as to reduce the fricti...
-Questions 4
1. Draw a sketch of a hammer removing a nail from a board. Where is the fulcrum? What class lever is it? Why? 2. Draw diagrams of the three classes of levers and give an example of each kind. 3....
-Chapter V. Pulleys, Inclined Planes, And Wedges. 37. Simple Form Of Pulley
The pulley is a machine which in its simplest form consists of a grooved wheel, made of wood, brass, or iron, with a rope or chain passing over it, fixed in a framework, and free to revolve. As the ty...
-38. Block And Tackle
The advantage of the single pulley may be increased by combining several pulleys, as is done in the case of the appliance called the block and tackle. Fig.17. - A Fixed Pulley. Figure 18 sh...
-Problems On Pulleys
1. How much pull at P would be required to lift 150 lbs. at W? (Fig. 18.) 2. What force at W would just balance 200 lbs. at P? 3. With what force or how many lbs. is the rope C pulling on its fi...
-39. Wheel And Axle
The study of pulleys and tackles leads naturally to that of the wheel and axle, which consists of a wheel or crank attached to an axle. The weight is lifted or moved by means of a rope, belt, or chain...
-40. Comparison With The Pulley
In theory the wheel and axle is nothing more than a single movable pulley, which instead of being a lever of the second class, and always lifting the weight exactly at its center, is a lever of the fi...
-Problems On Wheel And Axle
Note carefully in all problems on the wheel and axle that more force is required the faster the weight is lifted. Moreover, if the axle is made smaller, the weight will be lifted more slowly and less ...
-41. Inclined Planes
Another simple machine, called an inclined plane, is a slope used to enable a small force, such as the strength of a man, to overcome the weight of a large body. When, for example, it is necessary to ...
-42. An Example Of The Inclined Plane
Figure 26 represents an inclined plane supporting a ball A which is free to roll on an axle through its center. A cord attached to the yoke of the axle passes over a guide pulley B to a counterweight ...
-Problems On Inclined Planes
1. Neglecting friction, what force is necessary to keep a weight of 100 lbs. stationary on an inclined plane, the perpendicular height of the plane being 4 ft. and the length of its incline 14 ft.? ...
-43. The Wedge
A combination of two inclined planes joined at their bases is called a wedge. This simple machine is used to split wood, rocks, etc., and to raise heavy weights short distances. The power of the wedge...
-44. Application Of The Principle Of The Wedge
Just as the power of the inclined plane is proportional to the height and length of the plane, so is the power or force applied to the wedge proportional to its height and length. In this latter case,...
-Problem On The Wedge
A single wedge is 2 ft. long and 4 in. thick. What force must be applied to it to lift a weight of 600 lbs., neglecting friction? ...
-45. The Principle Of The Screw
The screw possesses great industrial utility in pressing bodies together or in raising weights, and may be classed among the simple machines. The screw is an inclined plane, and the effect of a screw ...
-46. Jack Screw
The ordinary jack screw is a good example of the wedge principle. It is a screw in combination with a lever. Figure 31 shows a common jack screw. The thread is the inclined plane or wedge and the c...
-Problem On The Jack Screw
A jack screw has a single thread, seven turns to the inch, and a handle 18 in. long. If a force of 50 lbs. is applied to the end of the handle what weight can be lifted, neglecting friction? (Take ...
-47. Measurement Of Machine Power
It is often very desirable to determine the power necessary to operate a machine. This may be done by means of instruments called dynamometers. The prony brake is one of the most simple and familiar e...
-48. Another Form Of Prony Brake
Figure 33 shows the prony brake as generally constructed. The clamp shoes c and d are clamped to the pulley with bolts a, a. As the pulley revolves in the direction indicated by the arrow, the tendenc...
-49. The Cost Of Mechanical Advantage
It has been shown that by the use of tools and machines which are all based on one of the six principles just described, it is possible to apply a small force to overcome a large resistance. This adva...
-50. The Effect Of Friction
Thus far we have considered the relations of speed, force, and resistance from a somewhat theoretical standpoint; in actual practice a deduction has to be made from the advantage apparently gained bec...
-51. Use Of Ball Bearings
Rolling friction is friction due to a solid rolling-over a smooth surface, as in the case of a car wheel moving over a rail, while a sliding friction is due to the sliding of the same particles of a w...
-52. Measurement Of Friction
In all machines there is more or less friction. The work done by the acting force always exceeds the useful work by the amount that is transformed into heat. The ratio of the useful work to the total ...
-Questions 5
1. A crane consists of what simple machines? 2. Name a number of twisting tools and appliances such as are used in placing a nut in position. Notice the manner in which they are used. Are two dis...
-Chapter VI. Laws Of Motion. 53. Three Laws Of Motion
Some interesting facts about the motion of bodies, which we ordinarily find out only as the result of long experience, can readily be understood by a knowledge of the laws of motion and momentum. A bo...
-54. Momentum Of Bodies
The momentum of a body is the quantity of motion in the body, and is the product of the mass and the speed. As an example: To find the momentum of a body 9 lbs. in weight, moving with a velocity of...
-55. Gravitation And Center Of Gravity
If we take a thin bar of iron and place it on a table, it will remain there. Remove the support, and the bar will fall to the ground. All bodies act in the same way. The earth attracts them, and this ...
-56. The Line Of Direction
A perpendicular line drawn from the center of gravity to the earth is called the line of direction. This imaginary line is of great importance in the construction of buildings, chimneys, and other tal...
-57. Mercury Plumb Bobs
Mercury plumb bobs (Fig. 36) tare usually made of hollow steel rods filled with mercury or quicksilver. Consequently they are unusually heavy in proportion to their size, and their centers of gravity ...
-58. Acceleration Due To Gravity
If a body falls freely in vacuum, that is, without resistance from the air, its velocity will not be constant throughout the entire fall, but will increase at a uniform rate. This uniform increase in ...
-59. Kinds Of Motion
Motion may be uniform or variable. When equal distances are traversed or covered in the same length of time the speed is constant. On the other hand, when the speed changes and equal distances are not...
-60. Cams
In a great many machines, such as looms, sewing machines, printing presses, punch presses, automobile engines, etc., it is often necessary to give to each machine a motion peculiar to itself. In one m...
-61. Centrifugal Force
Rotating bodies like grindstones, fly-wheels, etc., are built to run at a certain maximum speed. If this speed is exceeded the body may fly to pieces, as there is a tendency for particles of a rotatin...
-62. Force Expressed Graphically
Sometimes it is necessary to express or measure a force or forces graphically, that is, by means of lines. This is particularly true in the building of machinery and structures, where the results of t...
-63. Different Kinds Of Energy
There are, as noted in Chapter III (Mechanical Principles Of Machines. 22. Why Machines Are Used), many forms of energy, such as chemical, electrical, muscular, mechanical, etc. Any one form may be tr...
-64. Springs As A Source Of Energy
Springs are useful as machine parts, because of their capacity for yielding to force without permanently losing their shape - technically called their permanent set. Wound springs possess potential ...
-65. Weights As A Source Of Power
Weights are used as a source of energy when uniform pressure or action is desired. The proper tension is maintained on a rope by means of a weight suspended on a movable pulley. There are many applica...
-66. Accumulated Energy
We know that energy tends to accumulate in our muscles while at rest and that it can then be expended either gradually or by one effort, but to no greater extent than the reserve force that has been a...
-Questions 6
1. Explain why the wind is able to do the work of turning a windmill. 2. When the wood-chopper chops wood he usually swings the axe high when he comes to a knotty piece. Why? 3. Why is it more c...
-Chapter VII. Mechanics Of Liquids. 67. The Utilization Of Liquids In Industry
Liquids, particularly water, possess certain properties which render them invaluable for many industrial purposes. These properties form the bases upon which hydraulic machines and many other devices ...
-68. General Properties Of Liquids
Water and all other liquids resemble solids in that they possess a definite size; that is, they occupy a definite space. Liquids differ in that they have no definite shape. The shape of a liquid is th...
-69. Water Pressure
Water exerts a pressure on the bottom and sides of the vessel which holds it. Fill a vessel 1 cu. ft. in volume with water. If the water is weighed it is found to weigh about 62.5 lbs. Therefore 62.5 ...
-70. Hydraulic Press Machinery
It has already been shown that when pressure is applied to any part of a confined liquid, the pressure is transmitted equally in all directions. This law of Pascal is utilized to increase or multiply ...
-71. Uses Of Hydraulic Machinery
For the majority of operations requiring very great force applied through a comparatively short stroke, as in riveting, punching, shearing, lifting, forging, flanging, and many other similar operation...
-72. Capacity Of Pipes
In computing the capacity of pipes used to convey liquids one should remember that the capacity varies with the area, and that the areas of similar figures vary as the squares of their corresponding d...
-73. Water
A manufacturer usually stores quantities of water for manufacturing purposes in a tank at the top of each of the different buildings of the plant, but in case the factory or mill is near a stream, the...
-74. Dams And Water Wheels
Look at a mill or factory erected on the side of a stream. The water will usually be found confined by a wall of earth or stone. The water runs from the stream through an opening called a canal and th...
-75. The Pelton Wheel
The Pelton wheel (Fig. 48), a modified form of undershot wheel, has cup-shaped buckets sticking outward at regular intervals around its circumference. There is a partition in the center of each bucket...
-76. Wasted Water Power
Very few people realize the vast amount of water energy that goes to waste every year. Every particle of falling or running water represents energy, the amount of which depends upon the quantity and t...
-77. Measurement Of Flowing Water
Oftentimes, as when water is sold to a corporation or city, it is necessary to know the quantity of water coming down a stream. To measure this a device called a weir (Fig. 49) is constructed at the s...
-78. The Law Of Buoyancy
Explanation of why certain substances float on water depends upon what is called the law of buoyancy. When a ship is constructed, it is necessary to lay out the plans in accordance with the principle ...
-79. Stability Of A Ship
A ship at sea is subject to rolling and pitching and must be designed to be stable and not capsize. Rolling is the motion of a ship from side to side. Pitching is the alternate rising and falling of b...
-80. Specific Gravity
The specific gravity of a substance is the number of times it is heavier than the weight of an equal bulk of water. It may be expressed thus: Specific gravity (sp. gr.) = ...
-81. Hydrometer
The common method of determining the specific gravity of liquids is by means of the hydrometer (Fig. 52). This instrument consists of a glass tube with mercury or lead shot in the bottom to keep it in...
-82. Beaume Hydrometer
The Beaume hydrometer is used to determine the strengths of liquids in bleacheries, etc. The readings are expressed in degrees which may be changed into specific gravities by this formula: Sp. gr. ...
-83. Twaddell Hydrometer
The Twaddell hydrometer is used by many manufacturers. The readings may be converted into specific gravity from this formula Sp. gr = 100 + .5N / 100--------------- N is the Twaddell reading. ...
-Questions 7
1. Is water necessary for industry? Explain. 2. What great property do liquids possess that solids do not? What use is made of water in industry? 3. A liquid is often used as a part of machinery...
-Chapter VIII. Properties Of Gases. 84. Gas Pressure And Industry
There are many tools driven by air pressure, and there are a number of devices that depend upon the properties of gases for their action. Therefore intelligent knowledge of trade work frequently depen...
-85. Three States Of Matter
Ice, water, and steam represent the three states of liquid matter. A block of ice has a definite form and volume. Water has a free, level surface, but assumes the shape of the containing vessel. Steam...
-86. Expansion Of Gases
Gases are said to be perfectly elastic because they have no elastic limit and expand and contract alike under the action of heat. That is to say, every substance when in the gaseous state and not near...
-87. Principle Of The Barometer
Gases, though generally lighter than air, all have a definite weight. This weight depends upon the volume of the gas and the pressure exerted, as may be proved by means of an instrument called a barom...
-88. History Of The Barometer
In 1643, more than two hundred years ago, an Italian, named Torricelli, filled a glass tube, 33 in. long and open at one end, with mercury. Putting his finger over the open end so as to keep the mercu...
-89. Sands Of Barometers
The barometer in its simplest form consists of a long inverted vacuum tube, sealed at the upper end. The lower end dips into a cup of mercury. A graduated scale on the side of the tube measures the ri...
-90. Aneroid Barometer
The barometer most commonly made for commercial purposes is the aneroid barometer (Fig. 54). The word aneroid comes from the Greek and means not wet, and was selected because this type of baromete...
-91. Properties Of Air
The air or atmosphere which surrounds the earth is a mixture of two very different gases called oxygen and nitrogen. To every 21 parts of oxygen the air contains 79 parts of nitrogen. There are always...
-92. Moisture In Air
Absolutely dry air is a thing unknown in the natural world. The atmosphere is like a great sponge. It greedily takes up water and gives it back only when it has more than it can hold. Very few people ...
-93. Manufacturing Of Ice
Ice-making and cold storage depend upon the scientific principle that ammonia evaporates readily and absorbs a great deal of heat in passing from a liquid to a gaseous state. Apparatus for the manufac...
-94. How The Gas Is Condensed
The ammonia gas is taken from the refrigerating section and compressed by a pump. The ammonia starts from the compressor under a high pressure and temperature and passes to a cooling coil, which is th...
-95. Air Pumps
It is often desirable to force air into or remove it from a vessel. Air is forced into a vessel by machines called air pumps, air compressors, condensing pumps, and blowing engines or blowers. The air...
-96. Boyle's Law
When the outside temperature is the same as that of the air within a vessel, the product of the pressure and volume is constant. This is called Boyle's Law. To illustrate: If the volume of a gas is 2 ...
-97. Pneumatic Tools
A pneumatic tool consists of a cylinder with a handle, which contains a working (percussion) piston with various air ports, a cap nut, and a spring. Air is usually supplied to pneumatic tools from air...
-98. The Use Of Compressed Air In A Sand Blast
Sharp sand under air pressure is used in etching or frosting glass and cleaning castings. The pressure of the air and hardness of the sand is governed by the class of work. A sand blast outfit incl...
-99. Siphon
In commercial and industrial plants it is often necessary to remove a liquid in a small stream from a large cask, without disturbing a sediment, to fill smaller receptacles. This is particularly true ...
-Questions 8
1. Why do clothes dry more quickly on a windy day than on a quiet day? 2. Does sprinkling the street on a hot day make the air cooler? If so, why? 3. In what part of the summer is the heat oppre...
-Chapter IX. Heat And Expansion. 100. Generation And Movement Of Heat
If we file a soft iron nail for a moment and then feel the file surface, we find that it is warm or hot; that is, the surface of the file is warmer than the body. Another way of expressing the same id...
-101. The Manufacture Of Thermometers
For the measurement of modern temperatures there arc two standard thermometers: the Fahrenheit used in this country and England for ordinary purposes, and the Centigrade used in Continental countries,...
-102. Measurement Of Temperature In Industry
Thermometers assist us in comparing or fixing the temperature of certain industrial operations. This is important, as in a great many manufacturing operations it is necessary to know when a certain te...
-103. Relation Between Fahrenheit And Centigrade Scales
While all temperature measurements in American and English shops are expressed according to the Fahrenheit scale, it is often necessary to change the Fahrenheit into the Centigrade readings. Below is ...
-104. Heat Units
The unit of heat that is used in the industries and shops of England and America is the British thermal unit (B. T. U.) It is the quantity of heat required to raise 1 lb. of water to a temperature of ...
-105. Latent Heat
Examine a pan of water over the fire. Note that the heat passes first to the particles of the pan, then to the water nearest to the source of heat. As these particles expand, they become lighter and p...
-106. Steam Pressure
When steam is generated under ordinary conditions it is termed steam of one atmosphere (15 lbs. per square inch). One cu. in. of water will produce approximately 1 cu. ft. of steam (1728 cu. in.). I...
-107. Specific Heat
If equal amounts of copper and water are heated, it becomes evident that it takes a great deal more heat to raise 1 lb. of water 1 F. than to raise 1 lb. of copper. The unit of heat has already b...
-108. Boiling Point And Vacuum Pan
At the sea level, with an atmospheric pressure of 29.922 in. of mercury in the barometer - in other words at a pressure of 15 lbs. on the square inch - water boils at a temperature of 212 F. (100...
-109. Expansion Of Metals
Heat causes metals to expand. The expansion of unit of length for one degree is called the linear coefficient of expansion. The increase per degree for unit of surface is called surface expansion; for...
-110. Expansion Of Substance
When a substance consisting of two or more bodies which have different coefficients of expansion undergoes any change of temperature, it is subjected to stresses, since its various parts do not expand...
-111. Drying And Evaporation
The theory which underlies the process of drying is that dry air is capable of absorbing moisture; hence by circulating currents of dry air in and around wet substances, the absorbing power of the air...
-Questions 9
1. When is a body hot? 2. When metals begin to melt, they liquefy at once. Why? 3. Why is ice packed in sawdust? 4. Why does a draft extinguish a flame? 5. Which will heat more quickly, ro...
-Chapter X. Light, Color, And Sound. 112. Characteristics Of Light
We see objects by means of what we call light. Light comes from the sun by means of vibrations and produces an effect on the eye. These vibrations may also come from illuminated objects, but such obje...
-113. Refracted Light
Light travels faster in a rare than in a dense substance. Therefore when a ray passes from a rarer to a denser substance, it is bent on entering and on leaving the denser substance, and in both cases ...
-114. Composition Of Illuminants
All practical illu-minants are made of carbon brought to incandescence (glowing). The types of illuminants fall into two classes: first, particles heated by the combustion of their own carbon, such as...
-115. Standard Of Light
The only standard of light used in this country is the English standard candle. The unit is one candle-power, which is the amount of light given off by a spermaceti candle, weighing 1200 g. and burnin...
-116. Importance Of Proper Lighting
The problem of an adequate amount of light presents itself to every manufacturer and city-dweller. With the increasing value of space and the constant crowding of buildings, the natural source of ligh...
-117. Incandescent Lamps
The most common form of electric lighting at the present time is the incandescent lamp. It consists of a slender filament of some highly resisting material prepared from carbonized paper or bamboo and...
-118. The Nernst Lamp
The Nernst lamp has a filament of compressed oxides of certain rare metals. This filament conducts electricity only when heated to a high temperature, and as it is not combustible it need not be enclo...
-119. Arc Lamps
The ordinary arc light is formed between two carbons. When a current of electricity is passed through these carbons, the great resistance offered causes the ends of the carbon to become very hot and t...
-120. The Drummond Light
The Drummond light is produced by exposing small pieces of lime to ignition in a blowpipe. Oxygen and hydrogen gases are directed upon the ball or disk of lime from separate vessels or gasometers thro...
-121. Gas Lighting
Luminosity depends upon the reflection of glowing particles, and since a yellow flame heats many of these small particles of carbon, it gives off more light than does a blue flame. Consequently, the y...
-122. Natural Gas
A form of gas called natural gas is obtained from the earth by drilling a deep well. Such gas is formed as the result of decomposition of organic matter under pressure and heat. It comes to the surfac...
-123. Manufactured Gas
Manufactured or artificial gas is used in most places in this country and is made by heating coal gas, that is, gas obtained by distilling coal. Artificial gas is used for both heating and lighting, b...
-124. Light And Color
The color of a body depends on its nature, and the light in which it is viewed. A scheme of color that is harmonious by daylight may be just the opposite at night when viewed by artificial light. Diff...
-125. Theory Of Color
Sunlight is called white light, and is, as just noted, composed of all the colors of the rainbow. When sunlight falls upon a body, a part of the light is absorbed by the body and converted into heat. ...
-126. Table Of Colored Lenses
The following table indicates the kind of colored lenses which should be used to nullify or prevent any injury to the eyes from the industrial processes tabulated below, Group ...
-127. Characteristics Of Sound Intensity
When a hammer strikes a piece of metal a noise is produced. The sound is caused by the particles of the two separate metals vibrating. The vibrations are transmitted through the air in a series of wav...
-128. Pitch And Quality
Pitch is the property of sound which determines whether the sound is high or low. Pitch is determined by the number of vibrations per second made by the sounding body. Comparatively slow vibrations pr...
-Questions Light And Color
1. Petroleum oil looks bluish green when it is on the water. Why? 2. Smoke and fine particles that float in the air deflect the short waves of light more than the long ones. Why? Why is the sky blu...
-Chapter XI. Principles Of Chemistry. 129. Chemical Properties
In previous chapters we have discussed the necessity of a thorough knowledge of the physical characteristics or properties of the various materials used in industry. It is equally important to underst...
-130. Mixtures And Compounds
The great variety of solids, liquids, and gaseous substances that are used in one form or another in every-day industrial operations may be divided into mixtures, compounds, and elements. Fig....
-131. Elements
Elements cannot be decomposed by any known method or divided into anything simpler. The smallest particles of elements are known as atoms. Elements are sometimes found alone in the earth, as are pure ...
-132. Metallic And Non-Metallic Elements
The most satisfactory way to classify elements is to consider them as metals or non-metals. Non-metallic elements are those that combine readily with metals to form compounds; for example, chlorine, s...
-133. Atomic Weight
Atoms are assumed to have a definite weight. Hydrogen is the lightest element and has therefore been selected as the unit of weight; all other elements are measured in terms of hydrogen. For example: ...
-134. Analysis
If an electric current is passed through water, made slightly acid to increase conductivity (ease of passage), the water will be decomposed or separated into its elements, oxygen and hydrogen, which c...
-135. Synthesis
As already stated, when the proper proportions by weight of oxygen and hydrogen are mixed and a spark passed through, water is formed. This change, often called a reaction, may be written as follows: ...
-136. Molecular Weight
The molecular weight of a compound is the sum of all the atomic weights in the compound. To illustrate: H1O is composed of two atoms of hydrogen and one atom of oxygen. According to the table of atomi...
-137. Law Of Combined Weights
When elements combine to form chemical compounds, they unite according to fixed proportions. To illustrate: When water is formed from the combination of hydrogen and oxygen there must be 2 parts of hy...
-138. Valence
If we examine a number of symbols of binary compounds (compounds made of two elements) of hydrogen, such as HC1, H1O, NH3, CH4, we find that the first compound contains one atom, the second two atoms,...
-139. Chemical Action
Chemical change is due to the action of chemical force, which like other forces cannot be described; but is known by its effects. It is quite different, however, from the other forces of gravitation, ...
-140. Hydrogen
Hydrogen is a colorless, odorless gas, burning with a pale blue flame and very little light, but with great heat. It is chemically prepared by the action of zinc or iron, and hydrochloric or sulphuric...
-141. Oxygen
Oxygen exists in a free state in the air, which is a mixture composed of 20% oxygen and 80% nitrogen. Oxygen is a colorless, odorless gas, and may be prepared by decomposing a compound rich in oxygen,...
-142. Oxidation
Oxygen unites readily with other elements, particularly metals, and forms compounds called oxides. For example: When iron is exposed to moisture and to the air which contains oxygen, it oxidizes and r...
-Questions 11
1. Why is a knowledge of the chemical make up of certain substances, such as iron, important? 2. What is the difference between a mixture and a compound? 3. Name a number of mixtures; compound...
-Chapter XII. Acids, Alkalies, And Salts. 143. Classes Of Compounds
Compounds may be divided roughly into four classes of substances: water, acids, bases or alkalies, and salts. ...
-144. Properties Of Water
Pure water is the commonest compound that exists. The water we use comes to us either in the form of rain or of melted snow from the mountains. Part of it trickles or percolates through the ground and...
-145. Importance Of Acids And Alkalies
In addition to water, the most important compounds or substances used in chemical changes are acids and alkalies. They may be called the fundamental chemical agents that produce chemical changes. It i...
-146. Nature Of Acids
An acid is a compound of hydrogen with a non-metallic element or a group of elements that act as one, called a radical. The acid may be a gas soluble in water, as muriatic acid, or a liquid, such as s...
-147. Mineral And Organic Acids
There are two kinds of acids - organic and mineral. Organic acids are those, such as carbolic acid, oxalic acid, etc., which contain the element carbon in their composition. Mineral acids are those co...
-148. Formation Of Salts
A salt is a compound of metallic and non-metallic elements or radicals. It is formed by the action of: (1) an acid on an alkali or base (a base is a compound of a positive, i.e., a metallic element, o...
-149. The Formation Of Alkalies
Alkali is the commercial and industrial name for a strong base, such as caustic soda (NaOH), caustic potash (KOH), and ammonium hydroxide (NH 4OH). An alkali is opposite to an acid in character and tu...
-150. Nomenclature Of Acids, Salts, And Bases
Acids usually have two names, the chemical and the common. The chemical names are given according to certain rules based upon the elements in the acid. The common name of the acid is the commercial na...
-151. Compounds Of Metals
When combined with other elements, metals form compounds named generally after the element with which they are united. Thus, compounds with chlorine are called chlorides; with bromine, bromides; and i...
-Questions 12
1. What are some of the common properties of an acid?. 2. Name the mineral acids. 3. Name some organic acids. 4. What is the composition of the so-called pickling solution used in trades? ...
-Chapter XIII. Physico-Chemical Processes. 152. Nature Of Physico-Chemical Processes
Certain processes like: 1. Solution 2. Ebullition 3. Evaporation 4. Precipitation 5. Clarification 6. Filtration 7. Crystallization 8. Sublimation 9. Distillation are physic...
-153. Solution
When a solid substance is placed in a liquid and dissolves without a change in its chemical structure, the resulting liquid is said to be a solution of the dissolved substance. The liquid used is call...
-154. Ebullition
Ebullition or boiling is the violent agitation produced in a liquid when it is heated from a liquid to a gaseous condition. The heat acts first on that portion of the liquid resting against the heated...
-155. Evaporation
Evaporation is the process by which a liquid is gradually changed into vapor which fumes into the air. Evaporation may take place at any temperature, but only on the surface of the liquid; thus it dif...
-156. Precipitation
Precipitation is the process of separating solid particles from a solution by the action of either heat, light, or chemical substances. The solid particles separated are called the precipitate, and th...
-157. Clarification
Clarification is the process of separating from liquids, without making use of strainers or filters, solid substances which interfere with transparency. The principal methods of clarification are: (1)...
-158. Filtration
The commonest method of separating solids suspended in a liquid is by filtration, i.e., by passing the liquid through the pores of some substance called a filter. The liquor that passes through is cal...
-159. Processes Of Purification
When new compounds are manufactured by means of chemical reaction, they are seldom pure. In order to purify the product one or more of the three processes of crystallization, sublimation, and distilla...
-160. Crystallization
The crude product obtained directly from a chemical reaction is usually amorphous (not crystalline). To obtain the substance in uniform, well-defined crystals and to separate it from impurities it mus...
-161. Water Of Crystallization
A great many compounds crystallize very easily, and are sold in a crystallized form. In crystallizing they take up more or less water from the solutions and this water forms a definite part of the com...
-162. Sublimation
Most solid substances melt when a certain amount of heat is applied to them. Upon being heated further they vaporize. There are a few substances, like ammonium chloride, which vaporize without melting...
-163. Distillation
Distillation is the process by which a liquid is boiled and its vapor condensed. It is used, like the processes of crystallization and sublimation, for purposes of purification. If impure water, for i...
-164. Chemical Properties Of Coal
The principal materials used for fuel are petroleum and coal. Ordinary hard coal is called anthracite coal, and the soft, lumpy kind that crumbles very easily is called bituminous coal. All fuels are ...
-165. Chemical Bacteria
Animal grease is not suitable as a lubricant because it soon becomes rancid, that is, it gives off a disagreeable odor and forms acids. Careful experiments show also that the changes which take plac...
-166. Composition Of The Earth
Most of the raw materials used in trade and industry have their source in the earth. A few of these substances, such as gold, are found in a free state, but as noted before, the more common substances...
-167. Object Of Lubrication
Lubrication is the application or introduction of some substance that will cling to or flow between two surfaces and thus prevent friction. Bearings and joints of engines and machinery are lubricated ...
-168. Kinds Of Lubricants - Oils
Lubricants may be divided into three general kinds or classes - fluid, plastic, and solid. To the first-named class belong the various oils; to the second, the greases; and to the third, such substanc...
-169. Greases
Greases are suitable for use on slow-moving machinery where the pressure is not great. Even where the speed is comparatively high, but the pressure is light, a grease will often give excellent results...
-170. Solid Lubricants
The solid lubricants, such as graphite, soapstone, etc., usually have but a limited field of use. A certain form of graphite lately introduced, however, has been shown in experimental laboratory tests...
-171. Requirements Of A Good Lubricant
The selection of the proper lubricant in any particular case depends, of course, upon the class of machinery in which it is to be used. If on light-running and high-speed machinery, such as is used in...
-Questions 13
1. What is a solution? 2. Will a cold solution dissolve more of a substance than a hot solution? 3. What is a solvent? Name two or three common solvents. 4. What is a saturated solution? How ...
-Chapter XIV. The Chemistry Of Common Industrial Substances. 172. Chemistry In Industry
There are certain chemical changes, such as the burning of forms of carbon, explosions, etc., that are very common in industrial life. Moreover, the chemical composition of certain building materials,...
-173. Forms Of Carbon
When an element is found in several forms which have essentially different properties, it is said to be allotropic in character. Carbon is such an element, the different forms or modifications of whic...
-174. Oxides Of Carbon
When any form of carbon or carbonaceous matter burns, it forms a gas called carbon dioxide. If there is insufficient air or oxygen and considerable heat, a lower form of the oxide, called carbon monox...
-175. Hydrocarbons
The many compounds of carbon and hydrogen are called hydrocarbons. Carbon unites with elements, particularly metals, to form carbides, such as calcium carbide and silicon carbide. Calcium carbide is m...
-176. Flame
When gases are burned a light is given off. This light is called a flame. Flame is due to the combination of a gas with the oxygen of the air. A flame may be luminous, as in the case of an ordinary ga...
-177. Compounds Of Carbons
The following are the names, symbols, and uses of some of the most important classes of carbon compounds: Class of Compounds Composition Use Car...
-178. Gunpowder
Ordinary gunpowder is a mixture of charcoal, sulphur, and potassium nitrate. The efficiency of gunpowder depends upon the formation of a large volume of hot gases in a closed space. The pressure exert...
-179. Sand
Sand is composed of silicon dioxide (symbol SiO2). On account of their hardness, some varieties of sand and mixtures are used for grindstones. ...
-180. Glass
When sand and several other substances are mixed and heated, the fused mixture forms glass. The coloring of glass is caused by the introduction of oxides of metals into the heated mass. ...
-181. Clay
Clay is an impure form of aluminum silicate. Clay is formed by the slow breaking up or decomposition of certain parts of rocks called the feldspars (silicates of aluminum, sodium, or potassium). The...
-182. Properties Of Clay
The principal property of kaolin, or clay, is that it becomes slightly soft (plastic) when wet and may be molded into various shapes. When clay is heated it shrinks and in cooling becomes very hard. T...
-183. Porcelain
Porcelain is a glazed material used for insulators, etc. It is made by mixing kaolin, fine sand, and powdered feldspar, shaping the mass, and then heating it to a high temperature. The surface is glaz...
-184. Earthenware
Impure plaster clay, when wet, shaped, and heated to a moderate temperature may be used for tiles, etc. ...
-185. Bricks
Many materials used in building construction, such as bricks, drain pipes, etc., are made from impure clay by wetting, molding, and then heating the mixture sufficiently to harden it. The red color in...
-186. Mortar
To make mortar a thick paste is formed by mixing lime, sand, and water. This paste is placed between bricks or stones and slowly hardens or sets by-losing water and absorbing carbon dioxide. The obj...
-187. Cement
Cement is either a natural or artificial mixture of limestone, clay, sand, and iron oxide. Limestone is an impure form of calcium carbonate mixed with silica (sand) and clay. When the limestone contai...
-188. Bleaching
A better appearance may be given to cotton and many other fabrics by passing them through bleaching solutions. The most effective bleaching agent is bleaching powder, a white powder made by passing ch...
-189. Dyeing And Dyestuffs
The process by which coloring is added to fabrics by means of dyestuffs is called dyeing. Dyeing may be done in one of three ways: (1) by immersing loose raw material, such as unspun cotton threads, i...
-190. Printing On Fabrics
It is often desirable to print a colored design on a fabric that has been already dyed. There are three modern methods of printing patterns: direct printing, discharge printing, and resist printing. ...
-191. Sizing
Sizing is a process of applying a thickening agent or mixture to cloth, paper, etc. The change brought about is distinctly physical. The object of sizing is to add weight, strength, and smoothness (lu...
-192. Mercerizing
Cotton may be made to resemble silk, so far as the luster is concerned, through the application of a solution of caustic soda under tension. This process is called mercerization. The effect of the cau...
-193. Gassing
The luster of mercerized cotton may be increased by passing the material rapidly over a platinum plate heated to a very high temperature. The effect is to take off the loose fibers. This operation is ...
-194. Spontaneous Combustion
Spontaneous combustion is an expression used to explain the setting on fire of a substance without the employment of any external agent, such as a lighted match, a flame, or a spark. To illustrate: Th...
-195. Chemical Solution For Extinguishing Fires
The most effective method of extinguishing fire is by means of a solution used in chemical fire apparatus. This solution is much more efficient for fire-extinguishing purposes than plain water, becaus...
-Questions 14
1. Why is a knowledge of the chemistry of common industrial substances desirable? 2. What is the meaning of the expression carbon has four allotropic forms? 3. Why do people prefer crystalline...
-Chapter XV. Magnetism And Electricity. 196. Nature Of Magnetism
When we take a lump of lodestone, which is an iron ore, and place it near a piece of iron, the lodestone will attract the iron. The iron in its turn will then attract particles of iron. The iron is ca...
-197. Shapes Of Magnets
Magnets are of two shapes: straight or bar (Fig. 68) and horseshoe (Fig. 69). In every magnet there is a limited space surrounding each end or pole in which its magnetic properties are exhibited. This...
-198. The Mariner's Compass
Experience shows that, in all cases, like poles of magnets repel and unlike poles attract. This principle, called the law of magnets, is utilized in the device known as the mariner's compass (Fig. 70)...
-199. Nature Of Electricity
As we look about us we find electricity moving the cars on which we ride and producing the light by which we see at night, and we naturally ask, What is electricity? That question cannot, as yet, be...
-200. Relation Of Magnetism To Electricity
If a piece of copper wire through which a current of electricity is flowing is passed through a cardboard or glass plate and the card or plate is sprinkled with iron filings, the filings arrange thems...
-201. Electromagnetic Force
Soft iron retains very little magnetism and yet it can be magnetized to such an extent that it can be utilized in lifting large bodies. When a bar of soft iron, in the form of a horseshoe, is wrapped ...
-202. Chemical Means Of Generating Electricity
Electricity may be generated by chemical agencies. When any two different metals, such as zinc and copper, are placed in an acid or solution and wires are attached to them and connected, a current of ...
-203. Electrolysis
The breaking up of a substance by passing electricity through a solution of the substance is called electrolysis and the solution in which it takes place an electrolyte. This process is of great indus...
-204. Units Of Measurements
A quantity of electricity, like a quantity of water, may be measured. Since the flow or quantity of water depends on the pressure or head and on the resistance of the pipes, so the quantity of elect...
-205. Ohm's Law
There is a definite relation between the volts, ohms, and amperes of a circuit of electricity. This relation was first stated by a man named Ohm, and is known as Ohm's Law. The quantity of electric...
-206. Measurement Of Electric Power
Electric power is measured in the same way as is water power. Water power is equal to the quantity of water in pounds that falls per minute multiplied by the head or drop in feet. Electric powe...
-207. Simple Voltaic Cell
The voltaic cell (Fig. 74) consists of a strip of zinc and a strip of copper in a glass jar nearly full of sulphuric acid, supported side by side without touching each other. These two metal strips ar...
-208. Battery Cells
When electricity is desired for bells, burglar alarms, etc., it is obtained from battery cells. The electricity is generated by chemical means. There are many forms, each of which has its advantages a...
-209. Dry Cells
Dry cells (Fig. 75) are not actually dry. They contain the same ingredients as the Leclanche cell, but instead of containing a fluid electrolyte they have the solution absorbed in a plastic mass of ma...
-210. Storage Batteries
The storage batteries of commerce (Fig. 76) are built up with electrodes composed principally of lead peroxide (PbO2) as the positive electrode, and sponge lead as the negative electrode. The positive...
-211. Arrangement Of Electrical Apparatus
A group of cells or electrical apparatus may be arranged in different ways. The wire from the zinc of the first cell may be connected to the carbon of the second, etc. (Fig. 77), or the wire from the ...
-212. Galvanometer
One of the instruments used to measure electricity is called a galvanometer. It depends for its usefulness on the principle of magnetism. There are many varieties of this device. The D'Arsonval galvan...
-213. Ammeter
An ammeter (Fig. 80) is simply a commercial form of galvanometer. It is constructed in the same way, but only a small fraction of the current to be measured passes through the coil. The greater portio...
-214. Voltmeter
The voltmeter is an instrument used to determine the voltage of a circuit. It consists of a light, rectangular coil of copper wire wound upon an aluminum frame, pivoted in jeweled bearings, and capabl...
-215. Electric Pyrometers
In certain manufacturing processes it is necessary to determine the temperature of furnaces. Hence the need of some instrument that is simple, accurate, and capable of being handled by a workman witho...
-216. Galvanometers And The Measurement Of Heat
Galvanometers can also be used to measure temperature because, as noted above, an electric current is formed when metals are heated. The current thus produced is proportional to the temperature to whi...
-Questions 15
1. What is magnetism? 2. Explain the difference between a natural and an artificial magnet. 3. Describe the shapes of magnets. 4. Explain the expressions: magnetic flux, lines of force, ...
-Chapter XVI. Frictional Or Static Electricity. 217. Nature Of Current
When certain bodies, such as leather belting and pulleys, paper and steel plates, or cotton and steel rolls, are rubbed together, sparks are frequently produced. This kind of electricity is called fri...
-218. Leyden Jar
Static electricity may easily be drawn off and bottled up in what is called a Leyden jar. This is a glass jar (Fig. 82) three-quarters of the surface of which is coated inside and outside with tin-foi...
-219. Loss Due To Frictional Electricity
Frictional electricity causes considerable loss in the manufacture of paper, cotton, wool, etc. When the paper or material passes over machines, two forms of electricity are generated, each with diffe...
-220. Electric Neutralizer
Frictional electricity may be removed by attaching to the machine a device called a neutralizer, which is really a transformer. This device may be bolted to the wall or ceiling in any convenient pl...
-221. Lightning
Much of the electricity of the air is caused by the rubbing of moist air against dry air. A great deal of moisture is made by the sun or wind turning into vapor or mist the salt water of the ocean. Mo...
-222. Danger From Lightning
If a cloud filled with one kind of electricity comes near the earth when the latter is filled with the opposite kind, the cloud may discharge its electricity to the earth. If any tall object, such as ...
-223. Forms Of Lightning
We see lightning in several different forms; sometimes its flash is straight, sometimes it looks forked or zigzag, sometimes it is round like a ball, and sometimes it spreads over the clouds like a sh...
-224. Cause Of Thunder
When lightning passes through air it leaves a vacuum, and the air rushing in to fill it makes the noise which we call thunder. We do not usually hear this until some time after the flash of lightning ...
-225. Use Of Lightning Rod
Lightning on its way to the earth always follows the best conductor and consequently will leap from side to side to find a building or a tree. It is attracted to pointed things rather than to round or...
-Questions 16
1. What is frictional electricity? 2. Has frictional electricity industrial importance? 3. What is a Leyden jar? 4. Does frictional electricity cause any danger? Explain. 5. How may this d...
-Chapter XVII. Generation Of Electricity On A Commercial Basis. 226. Generating Large Amounts Of Current
We have studied how electricity is generated by chemical means in batteries and by friction. These two forms of electrical energy are very valuable for commercial purposes where a small current is suf...
-227. The Principle Of A Dynamo
The generation of electricity by a dynamo is based on a principle of magnetism called induction. When the lines of force that pass from the north to the south pole of a magnet are cut by a wire there ...
-229. Commutator
We have seen that the current generated in the coil is alternating. Alternating current is very valuable for lighting and power, but there are cases in electroplating and charging storage batteries wh...
-230. Armature Brushes
The electricity is taken off the commutator by strips of carbon which touch or lean upon it. There are usually two brushes on the opposite sides of the commutator. The brushes, when adjusted, can shif...
-231. Armature And Core
The armature of a dynamo (Fig. 84) consists of a steel or iron shaft on which are mounted a large number of thin circular iron disks held together by bolts. This arrangement makes a cylinder with a gr...
-232. Action Of A Dynamo
A dynamo, then, is a machine for transforming mechanical energy (which is the energy that rotates the armature) into electrical energy, and for forcing the current of electricity through the wires. ...
-233. Classes Or Types Of Dynamos
There are three classes of dynamo machines on the market - series, shunt, and compound - each one adapted for special work. They differ in the manner in which their field magnets are wound. ...
-234. Series Machine
A series machine (Fig. 85) is a dynamo which allows all the current produced to pass through the field magnet coils by taking the wire from one brush and carrying it the required number of times aroun...
-235. Shunt Machine
A shunt dynamo (Fig. 86) is a machine which has only a portion of its total current passing through the field magnet coil. It is used in all cases where it is desirable to have a constant pressure vol...
-236. Compound Machines
A compound dynamo (Fig. 87) is one having two series of windings; one series winding, around the part through which the main current flows, and a shunt winding through which a fraction of the main cur...
-237. Direct Connected Machine
A direct connected dynamo is one which is driven by an engine without the use of a belt; that is, the armature shaft is connected to the engine shaft by means of a flexible device; or the engine shaft...
-238. Direct And Alternating Dynamos
While dynamos vary in the manner of winding the fields and armatures as described above, the most important difference between the different types is in the kind of current generated. This classificat...
-239. Care Of Dynamo
A dynamo to run properly must be kept clean and dry. The parts that require the greatest care are the commutators and brushes. The commutator should be kept clean by wiping it with a hard cotton cloth...
-240. Electric Motor
An electric motor (Figs. 88, 89, 90, 91) is a machine for transforming electrical into mechanical energy. An electric current causes the armature to rotate, and the mechanical energy due to the rotati...
-241. Kinds Of Motors
There are different kinds of motors as there are dynamos. Series motors are used in hoists, cranes, railways, etc., where it is necessary to start with a full load and where the automatic regulation o...
-242. Electric Railway Motors
The work of the electric railway requires a special type of motor of great flexibility. For example, the current demanded by a motor in starting a car is always in excess of the current afterwards req...
-243. Resistance Box
A device to resist or check the flow of current is commercially called a resistance box. It generally consists of an insulated wire, wound in a spool, the ends or terminals of which are fastened to la...
-244. Rheostat
A rheostat consists of a number of coils of wire connected in series for the purpose of introducing resistance into the circuit. An adjustable device allows the resistance to be varied by cutting out ...
-245. Starting Box And Controller
A starting box is a rheostat used to cut down the voltage in the line, when starting a motor. The current should flow through it only while the motor is attaining its normal speed, the resistance bein...
-246. Efficiency Of Dynamo
The efficiency of a dynamo is the quotient obtained by dividing the amount of electric power furnished by the dynamo by the amount of mechanical power delivered to the dynamo. It is measured by indica...
-247. Electric Transformers
The commercial requirements of users of electricity are best served by distributing electricity at high voltage and low amperage and by changing the same current into low voltage and high amperage by ...
-248. Fuse
A fuse is a safety device intended to melt when a current exceeding a certain strength passes through a conductor. Thus the fuse protects the conductor from being overheated by excess current. The fus...
-249. Circuit-Breaker
When a large volume of current is used it is necessary to have a device known as a circuit-breaker, as fuses are sometimes too slow in action. A circuit-breaker is practically a switch, which, when th...
-Questions 17
1. What is the commercial method of generating electricity? 2. What are the principal parts of a dynamo? 3. Explain the principle of a dynamo. 4. The strength of a current depends upon what f...
-Chapter XVIII. Transmission Of Electrical Energy. 250. Practical Uses Of Electricity
Mechanical energy is transformed into electricity because in this form it can be conducted very readily from a convenient place of generation or source of power, such as a waterfall, to any spot withi...
-251. Electrical Apparatus
Electrical apparatus work includes the manufacture of all electrical machines, instruments, and devices. This work is so varied and widely differentiated that no brief description can cover it. In gen...
-252. Outside And Inside Wiring
Outside wiring consists of the installation of all outdoor lines, such as general electrical power transmission lines, street lighting, telephone, telegraph, and signal lines. There are two general ty...
-253. Requirements Of The Trade
A very considerable amount of trade and technical knowledge is required by an electrician. The following are some of the details upon which an inside wireman must have ready and definite knowledge: (1...
-254. Switchboards
The output from generators and dynamos is regulated by means of switches on a switchboard (Fig. 9) which is divided into two sections: the machine panels, and the feeder panels. The machine panels are...
-255. Transmission Of Electrical Current
The electrical current must be transmitted from the power plant to different points of distribution in an economical manner; that is, with very little loss of electricity, and at the same time in a wa...
-256. Measurement Of Strength Of Current
Electricity is distributed from the power station where the energy is generated to the different points where it is to be utilized for power or lighting. The amount of work done or power consumed in...
-257. Size Of Wire
In distributing electricity there is, as previously stated, more or less resistance to its passage through wires. In overcoming this resistance heat is developed and energy is lost by the friction cau...
-258. Kilowatt And Kilowatt-Hour
Many people confuse kilowatt (kw.) and kilowatt-hour (kw.-hr.). Kilowatts (watts divided by 1000) represent the number of units of energy used at any one time. Kilowatt-hours mean the amount of energy...
-259. Injuries In Electrical Work
Injury in electrical work is usually caused by direct contact with a live conductor and may consist of either a shock, burns, or both. When the electric current enters the body, it causes more or l...
-Questions 18
1. Name some of the practical uses of electricity. 2. What are the possibilities and limitations of electrical heating? 3. Describe some of the principle lines of electrical work. 4. What is ...
-Chapter XIX. The Telephone And Telegraph. 260. History Of Telephony
Less than forty years ago there were no telephones. Today there are more than 10,000,000 in use and they are found in every civilized country on the globe. The United States has more than 7,000,000 te...
-261. Telephone Principles
Many people use the telephone daily without having the slightest conception of the principles upon which it operates. The fundamental principle is a comparatively simple one, involving merely the carr...
-262. Making A Connection
In order to understand how a call is made through a large city exchange, it is necessary to have in mind a distinct picture of a switchboard and to understand the functions of the various operators. (...
-263. The Supervising Lamps
There is, on the operator's switchboard, a supervising lamp associated with the calling plug as well as with the receiving plug. When a subscriber calls the operator, the supervising lamp under the re...
-264. The Listening Cam
The listening cam is a small key on the switchboard by means of which the operator puts herself in connection with a subscriber after having plugged in at his answering jack. After connecting two s...
-265. Cables And Distributing Frames
Wires enter and leave the telephone exchange building in the form of cables (Fig. 95). A cable is composed of pairs of twisted copper wires, insulated with spiral wrapping and enclosed in a lead casin...
-266. Construction Work
The work of telephone company construction crews is almost entirely outdoors. The linemen work in gangs under a foreman, and generally not far from their homes. During the summer, however, they travel...
-267. The Story Of The Telegraph
Samuel F. B. Morse, an American inventor, holds the most important place in the development of the telegraph. Although Wheatstone and Cooke in England occupied a distinct place in this field, the tele...
-268. Parts Of Telegraph
The telegraph is an instrument used to send messages to a distance by means of electricity. It is usually worked by electrical current or by an electromagnet. The instrument is made up of four separat...
-269. Steps In Telegraphing
To telegraph from one place to another it is necessary to stretch between the two places a wire, over which the electric current may flow. Iron wire is generally used, because it is stronger and cheap...
-Questions 19
1. How long has the telephone been used? 2. Who invented the telephone? 3. Explain the principle on which the telephone is based. 4. Describe the steps in telephoning. 5. Describe the cons...
-Chapter XX. Science Underlying Mechanical Drawing Supplies. 270. Mechanical Drawing - Supplies Required
Mechanical drawing plays a large part in directing the performance of all industrial operations. It is the guiding hand, so to speak, which directs the erector in the shipyard, the machinist in the sh...
-271. The Lead Pencil
A lead pencil consists of a stick of graphite in the center of a cylindrical piece of red cedar wood. This particular type of wood is selected because it can be cut easily and smoothly with a penknife...
-272. Drawing Paper
Paper is a fabric or kind of cloth composed of numerous fibers or threadlike filaments, the rough edges of which cause them to stick together. Drawing paper and other fine grades of paper are made fro...
-273. Rubber Erasers
Rubber erasers are used extensively in drawing to remove pencil and ink marks. They are made of rubber combined with sufficient sulphur to give the proper hardness. Other materials are added in varyin...
-274. The Working Drawing
The drawing from which the blue-print is made is called a working drawing. The method of preparing it is simple. The draftsman merely looks squarely at the object and draws the outline of it. By chang...
-275. Distinction Between Working And Perspective Drawings
A perspective drawing is one that portrays an object as it appears to the eye from one point of view. The rails of a car-track, for instance, appear to converge. The parallel lines of any object appea...
-276. Tracing Cloth
Tracing cloth consists of muslin cloth heavily sized and pressed to make it translucent and smooth. There is some oil in the sizing preparation, and consequently before the cloth is used, whiting or c...
-277. Tracing Paper
Tracing paper is made from tissue paper of an even texture, and possesses long and strong fibers. This tissue paper is treated with oil and solutions of resins and varnishes. ...
-278. India Ink
India or Chinese ink is always used in making the tracing of a mechanical drawing, because of its permanence, its distinct blackness, and because it is waterproof. Moreover, India ink, because of its ...
-279. The Blue-Print
When a mechanic in the shop receives a working drawing, it is in the form of a blue-print, a blue paper on which the lines of the drawing appear in white. A specially prepared paper, known as blue-...
-Questions 20
1. Describe the composition and manufacture of a lead pencil. 2. What constitutes a good grade of drawing paper? 3. Explain the composition of an eraser. What qualities must an eraser possess? ...
-Chapter XXI. Strength Of Materials. 280. Need Of Knowledge Of Strength Of Materials
Mechanics are often called upon to determine the size of rod or beam required to support a certain weight or force. Not all pieces of material have the same strength. The strength of any piece of mate...
-281. The Effects Of A Load Of Force On A Body
When a body is supporting a load, a force is acting on it. This force will produce a change, perhaps not very noticeable, in the form of the body. Unless this load is so great as to cause a break or f...
-282. Different Kinds Of Stresses
Stresses may be divided into the following five classes according to the action of the force producing them: (a) Tension (pulling stress) usually called tensile stress. (6) Compression (crushing...
-283. The Effect Of Strains
Since a strain is the lengthening due to the action of a stress it is measured in fractions or decimals of an inch. To illustrate: If a bar of steel, such as a piston rod, has been stretched or len...
-284. Bending Force
When a beam is bent, the forces at any point tend to pull the fibers apart in the upper part and push them together in the lower part, while the portion between the two is subject to less stress. The ...
-285. Measurement Of Stresses
Stresses are measured in pounds per square inch. For example, if we have a bar in tension there is a stress distributed equally all over its cross-section. In other words, if the bar is 1 in. squar...
-286. The Stress Of Elongation
Ultimate strength and the unit of ultimate elongation are closely related. The ultimate elongation is a strain produced in a unit of length by a stress equal to the ultimate strength of the material. ...
-287. The Stress Of Compression
Compression is one of the most common of all stresses and everywhere things are seen undergoing compression. The foundation walls of the shop, the legs of the table, the foundation of the lathe, the s...
-288. Testing Laws Applicable To Materials
Repeated experiments with materials in testing machines and in practice have proved that there are certain laws which always hold true. These laws may be enumerated as follows : I. When a body is s...
-289. Tables Of Strength Of Materials
The first thing to know in determining the size of beam or timber is the weight or force load the timber is to support and the location of the load. Very careful experiments have been made in testi...
-Average Tensile Strength Of Materials In Pounds Per Square Inch
Fig. 102. - Testing Machine. ...
-Metals
Antimony.............. 1053 Aluminum: Castings..... 15000 Sheet........ 24000 Bars........ ...
-290. Weight Of Metals Per Cubic Inch
It is often necessary in designing a machine to know the weight of its parts, and any good engineer's handbook will give the weights per cubic inch of all the metals. Not all kinds of iron weigh exact...
-291. Factors Of Safety
In building a machine or a structure of any kind, care must be taken not to subject any part to a stress that would strain it beyond its elastic limit. The usual practice is to divide the ultimate str...
-292. Strength Of Chains
Chains for hoisting weights are made from a good grade of wrought iron, which has a tensile strength of from 40,000 to 48,000 lbs. per square inch. Chains used for raising weights should never be made...
-Questions. Stresses
1. What name should be applied to the stress produced at point A in Fig. 103? 2. To what stress are the legs of the table subjected in Fig. 104? 3. To what stress is a boiler seam rivet subjecte...
-Factor Of Safety
For convenience in working the following problems we will use values given in the table below, unless otherwise specified. These are average values which have been established by actual test. ...
-Chapter XXII. Common Fastening Agents. 293. Nails
The most popular of all fastening agents is the nail. There are two common forms: wire nails (Fig. 107) and cut nails (Fig. 108). The wire nail is made of a cylindrical piece of wire, with one end sha...
-294. Screws
There are a great many varieties of screws, but the principal one is the wood screw (Fig. 1ll), which is made by machine. Wood screws were originally made with blunt points. It was then necessary to m...
-295. Bolts
A bolt (Fig. 112) is a special form of screw with a nut attached or screwed on the end to hold it in place. A bolt can be more easily removed than a screw. Many machine shops, especially railroad shop...
-296. Parts Of Screw Thread
Certain definitions in regard to the screw should be carefully noted. A screw may be either right-handed or left-handed. Right-handed means that, when turning it into a nut or threaded hole the screw ...
-297. Measurement Of Thread
Figure 115 shows how to measure the number of threads to one inch of a bolt. In this case the threads are an even 8 to the inch and we see that there are just 8 grooves from the end of the scale to th...
-298. Depth Of Thread
It is important to be able to find the depth of a thread, for upon this depends the cutting of all threads and the size of all tap drills. By referring to Fig. 117, we see that the depth of the thread...
-299. Kinds Of Screw Threads
There are many kinds of bolts and screws to meet different needs and in order to specify a particular grade of bolt or screw it is necessary to mention; Fig. 117. - Measurement of Pitch of Scr...
-300. Standard Threads
The two forms of screw threads in use in the United States are the common V thread and the United States standard thread, while the Whitworth screw is the most common in England. The V-shaped threa...
-301. Taps And Tap Drills
A tap is a tool for cutting inside or internal threads in holes so that the holes will hold tightly the bolts, screws, or studs which may be screwed into them. Taps are generally made from hammered ro...
-302. Teeth Of Taps
The teeth or cutting edges of taps are radial. The cutting edge of a tap penetrates the metal very much like a wedge. For this reason taps for taking very heavy cuts are backed off much more than fini...
-303. How To Determine The Size Of A Tap Drill
A simple method of finding a tap drill for a V thread, or a United States standard thread tap, is provided by the following formulas (see (a) Taper Tap (b) Plug Tap (c) Bottomi...
-304. Rivets
A rivet before being driven is a simple cylinder finished at one end with a head. Various forms of heads are shown in Fig. 121. The point of a rivet is formed when it is driven, while the rivet is hot...
-Questions 22
1. State the advantages and disadvantages of a cut nail. What causes a nail to split the wood? Fig. 121. - Rivet Heads and Points. 2. State the advantages and disadvantages of a wire nail. ...
-Chapter XXIII. Common Hand-Tools. 306. Kinds Of Hammers
Among the hand-tools there are a number of hammers that are common to most trades. Therefore it is necessary to know the principles underlying their construction and use. The small end of the ha...
-306. Kinds Of Chisels
The simplest form of metal cutting tool is the chisel, called a cold chisel. The mechanical principle of the cutting edge of the chisel is that of the wedge. Chisels for machine work differ from wood ...
-307. Kinds Of Files
A file is a bar of high-grade crucible steel, pointed at one end for a handle and having cutting edges or teeth extending from a point near the handle to the opposite end. The mechanical principle of ...
-308. Methods Of Filing
It requires a great deal of practice to file a surface flat, as there is a great tendency for the file to rock or fulcrum on the corners of the work and make the surface rounding or crowning. The wo...
-309. Use Of Scrapers
When a job cannot be finished accurately enough with a file, a tool called a scraper (Fig. 133) is used. Scrapers are generally made from octagonal steel flattened on both ends and tempered very hard ...
-310. Kinds Of Drills
Drill points are used for boring small holes in wood, iron, brass, or other materials. There are three kinds of drills; flat, straight-fluted, and twist drills (Fig. 134). The flat drill can be used f...
-311. Drills And Drilling
Most drills are made from round bars of tool steel hardened and tempered to suit the work to be performed, generally to a dark straw color. The flat drill is made in the shop and is used because it is...
-312. Mechanism Of Drill Points
To understand the principle of drilling efficiently, it is necessary to study the mechanism of a drill point. Drills are used to separate small particles of metal by scraping or cutting and to do this...
-313. Operation Of Reaming
It is difficult, if not quite impossible, to drill a hole to an exact diameter. For most work, however, a variation of a few hundredths of an inch is of no account, but when greater accuracy is requir...
-314. Kinds Of Reamers
When not carefully sharpened, all forms of reamers have a tendency to produce a rough hole. Too much clearance reduces the support of the reamer in the hole and tends to make it work unsteadily. Re...
-315. Emery Cloth
The art of finishing or polishing wood and metal is very old. Originally it was done by taking the dried skins of sharks and rubbing the material. Later sandpaper and emery cloth were invented. As nea...
-316. Polishing And Burnishing
Metal is polished to give it a fine finish and to produce a smooth surface which will reflect light to its highest degree - in other words to give it a shine. The principal substances or abrasives u...
-317. Development Of Grinding Stones
Tools were originally shaped by chipping one stone against another until the stone which was to be the tool was made the desired shape. When man learned the use of metal, he continued to sharpen his t...
-318. Corundum And Emery Wheels
Corundum is an extremely hard oxide of aluminum. Emery is a very hard, granular variety of corundum, containing a small amount of magnetite or hematite. Ground to a powder, these substances are used f...
-319. The Discovery And Use Of Carborundum
The discovery of carborundum nearly thirty years ago, brought into use a new and exceptionally efficient abrasive. In 1891, experiments with electric furnaces showed that when clay and crushed coke we...
-Questions 23
1. Draw a sketch of a hammer removing a nail from a board. Where is the fulcrum? 2. Would you gain more advantage in holding the handle of the hammer in the middle or the end? Explain. 3. Why ar...
-Chapter XXIV. Transmission Of Power. 320. Methods Of Transmitting Power
The power that drives a machine is usually transmitted in one of three ways: (1) from a fly-wheel in the power house to a pulley on a main line of shafting in the shop and then to another pulley on a ...
-321. Arrangement Of Shafting
The transmission of power by shafting is accomplished by means of pulleys and belts, or ropes attached to the shafts, which in turn are supported by hangers. Shafting consists of cylindrical bars of s...
-322. Formula For Horse-Power A Shaft Will Transmit
To find the horse-power which a shaft of a given diameter will transmit, multiply the cube of the diameter in inches by its revolutions per minute and divide by 92 for steel shafts and by 190 for wrou...
-323. Setting Line-Shafting
There are two points to be considered in setting line-shafting in line. One is that it should be either horizontally or vertically in line with its journal; the other that the line-shaft and counter-s...
-324. Flange Couplings
Line-shafting which is to encounter much shock and sudden variations of load must be coupled with what are known as flange couplings. The distance between the hangers must be regulated by the number o...
-325. Bending And Twisting Of Shafting
Shafts are subject to bending and twisting. The bending is due to the load strain of the pulley, while the twisting is caused by the rotation of the shaft. Because it is liable to be rendered useless ...
-326. Leather Belting
Most belts used in machine shops are made of oak-tanned leather (Fig. 141), but canvas is sometimes substituted for leather belting. Single belts are made from one thickness of leather or canvas, and ...
-327. Fastening Belts
There are several methods of fastening the ends of belts together. It is customary in the case of wide belts (8 in. and over) to fasten the ends by cementing. Narrow belts are fastened by lacing, wiri...
-328. Sag Of Belts
When placing in position shafts that are to be connected by belts, care should be taken to separate them by a proper distance, so that the belt may be allowed to sag a little when running. No arbitrar...
-329. Rope Drives
Sometimes instead of a pulley, a wheel with grooves on its circumference (Fig. 142) is used for rope transmission. The use of rope for the transmission of power is more common in Europe than in the Un...
-330. Measurement Of Coiled Belting
When belting is purchased it is not necessary to uncoil it to determine its length. It may be measured in the coil in the following manner: To the diameter of the coil in inches, add the diameter of t...
-331. Pulleys And Their Management
Pulleys are made of wood or steel (Figs. 143 and 144). They are measured by their diameter and by the distance across the face or rim. (a) Taper Cone Pulleys (6) Step Cone Pulleys F...
-332. Speed Of Pulley
The size of the pulley governs the speed of the machinery and this speed is determined by the relative movements of the pulleys and the ratios between their diameters and speeds. Pulleys are usually a...
-333. Size Of Pulley
To illustrate the method of finding the size of a pulley, suppose a shaft is to make 360 R. P. M. and that it is driven from a line-shaft making 180 R. P. M. The larger pulley on the line-shaft is alr...
-334. Object Of Gears
The liability of belts and ropes to slip when transmitting heavy loads renders their use practically impossible when a constant ratio of velocity between the driving and driven shafts must be maintain...
-335. The Principle Of Gearing
The principles underlying the design of gears may be best understood by considering the historical development of the gear. Originally transmission of power in machines was carried out by two smooth c...
-336. Types Of Gears
Of the different types of gears in use the principal ones are the spur (Fig. 149), the bevel (Fig. 150), and the worm (Fig. 151) gears. Spur gears are wheels with the teeth or cogs arranged round t...
-337. Teeth Of Gearing
Toothed gearing is employed for transmitting motion from one shaft to another. Under favorable conditions it is the most economical of all means of transmitting power from one shaft to another, but wh...
-338. Relation Between Speeds And Diameter
In the mechanical world or in speaking of machines, the expression geared to 75 is often heard. This means that one turn of the driving wheel will cause the circumference of the drive to pass over 7...
-339. Ratio Of Gears
Suppose we have two shafts, Dand F, as shown in Fig. 153 and that we want to connect these shafts by gears so that shaft D will make one revolution while shaft F makes two. In order to do this we m...
-340. Direction Of Gears
The number of turns or revolutions which a gear makes is always proportional to the number of its teeth. It makes no difference how many gears there are :n a train, the gears between the first and las...
-341. Gearing Terms
There are certain terms relating to gears with which the mechanic should be familiar. Some of the most important of these are explained below. (See Fig. 155.) Spur. - Spur originally meant a projec...
-342. Ratio Of Gear Measurements
Repeated designs and tests of spur gears prove that the dedendum (or addendum) should always have a certain definite ratio or relation to the diametral pitch which is: dedendum times diametral pitch =...
-Questions 24
1. State some advantages and disadvantages of the transmission of power by individual drive. 2. What is the mechanical principle involved in pulleys transmitting power by belting? 3. What is the...
-Chapter XXV. Boilers And The Generation Of Steam. 343. Source And Characteristics Of Steam
The source of energy used in driving many forms of machinery is the oil or coal consumed - usually in the boiler-room of the power plant. When this oil or coal is burned it gives off heat. The heat co...
-344. The Boiler Of The Steam Engine
The principal parts of a steam engine are the boiler and the engine. The boiler is a cylindrical steel vessel located over a fireplace. Fig. 157. - Heating Water by Steam. The arrow represents...
-345. Water-Tube Boiler
The water-tube boiler is the result of a demand for high pressures of steam. In this type of boiler the water is contained in tubes which, on account of their comparatively small size, reduce the thic...
-347. Joints Of A Boiler
It is very important that a boiler should safely withstand the pressure of steam for which it has been constructed. Though the tensile strength of the boiler plate is marked on it, it is necessary to ...
-348. Thickness Of Boiler Plate
The Boiler Inspection Department of Massachusetts recommends the following formula for determining the thickness of boiler plate: (Copyrighted by Millers Falls Co.) Fig. 161. - Butt Joint. ...
-349. Testing Boilers For Defects
Boilers are tested in two ways: (1) by hydraulic pressure, and (2) by the hammer test. The hydrostatic test consists in filling the boiler with water and then exerting by means of a boiler test-pump (...
-350. Boiler Repairs
Boilers may be repaired by placing a hard or soft patch on the defective part. For a hard patch, the defective part is cut out, rivet holes are drilled or punched around the opening, and the patch is ...
-351. Principal Parts Of A Boiler
The principal parts of a boiler are the shell, tubes, fusible plug, hand-hole, safety valves, and water gauge. The shell and tubes have already been explained. A fusible plug is a brass plug with a ta...
-352. Safety Valves
As the cylinder of the boiler is made to stand a certain pressure, any excess may cause it to burst. Therefore it is essential that the fireman should know when that pressure is exceeded. Various devi...
-353. Construction Of Safety Valves
Calculations for lengths of arms and weights required for any boiler pressure are obtained from the formulas for levers, taking into account the weight of the lever and valve. The center of gravity...
-354. Water Gauge
The function of the water gauge (Fig. 166) is to register the height of the water in the boiler. It consists of a small cast iron drum placed in an upright position in front of the boiler, provided wi...
-355. Boiler Pumps And Injectors
A boiler should have at least two means of feeding water, because one might fail to work. The water inside a boiler is usually kept at a proper level by either pumps or injectors. Steam pumps (Fig. 16...
-356. Measurement Of Pump Pressure And Capacity
The formula for lifting or forcing water either under pressure or head is as follows: P = H A W. Where H = the distance from the level of the source of supply to the point of discharge. A = area in...
-357. Measurement Of Water Cylinder Contents
To find the cubical contents of a water cylinder per stroke, in cubic inches, multiply the area of the piston in square inches by the length of stroke in inches. To find the contents in gallons divide...
-358. Injectors And Ejectors
The injector (Fig. 168) is an apparatus for forcing water against pressure by the direct action of steam on the water. It is universally used on locomotive and sometimes on stationary boilers. Steam i...
-359. Water-Heater
Before entering the boiler, water is heated in a heater by exhaust steam. This heater consists of a vessel filled with brass tubes. Steam passing through or around the tubes causes the temperature of ...
-360. Cleaning The Boiler
When the water is heated and converted into steam, the sediment or suspended dirt remains in the boiler and forms scales. These scales are composed principally of mineral matter and affect the economi...
-361. Care Of Boiler
The boiler should be inspected frequently during construction, and when completed should be thoroughly tested. After the boiler is in position and the brickwork completed, it should be allowed to stan...
-362. Firing The Boiler
Firing can best be done when combustion is good, as but little dense smoke then is given off. Dark spots in the fire, abundance of smoke, unsteady steam pressure, unsteady water line, dirty tubes, and...
-363. Chimneys And Flues
A chimney is a vertical flue, usually of iron or brick, for conveying the heated air and combustion gases from the fire to the outer air. It usually extends some distance above the tops of buildings. ...
-364. Theory Of Combustion And Smoke
Smoke is a byproduct of the combustion of fuel, and is invariably the result of incomplete combustion. It is composed chiefly of minute particles of carbon and steam, and is due largely to an excess o...
-365. Temperatures Of Steam
After steam has been once generated, the temperature remains constant, and the latent heat, not observable by the thermometer, is absorbed. The temperature of steam in contact with the water from whic...
-366. Terms Used In Calculations
One should be familiar with a number of terms which are frequently used in calculations. Heating surface means all surface having water on one side and fire or heated gases on the other. Grate s...
-Questions 25
1. Trace the energy used in a steam boiler from its original source. 2. Why is steam considered an aqueous vapor and not a gas? 3. Describe the properties of steam. 4. What properties of stea...
-Chapter XXVI. The Steam Engine. 367. History Of The Steam Engine
The steam engine is one of the most important mechanical contrivances used in trade and industry. With its discovery came the great industrial development of the world. The first steam engine was inve...
-368. Principal Parts Of Steam Engines
The principal parts of a simple engine (Fig. 169) are the frame, cylinder, Fig. 169. - Steam Engine. A - Cylinder B - Piston C - Slide Valve D - Steam Inlet E - Steam Ports F - Exhaust P...
-369. Purpose Of A Governor
The governor (Fig. 170) of a steam engine is a device which controls the supply of steam by letting into the cylinder just the right quantity. In the pipe which carries the steam from the boiler to th...
-370. Crank
The crank is a mechanical device employed for converting the parallel or reciprocating motion of the piston into a rotary motion. It is connected by a key to the shaft, which carries the fly-wheel. ...
-371. Dead Center
When the piston rod is fully out or fully in, and the connecting rod and the crank in consequence lie in a straight line, the crank is said to be at a dead point or dead center. When the crank is in t...
-372. Steam Valves
The steam is admitted into the cylinder of an engine by means of valves, as previously stated. There are three distinct types of valve - (1) slide, (2) Corliss, and (3) poppet valves. The slide val...
-373. Condensing Engines
Non-condensing or high-pressure engines are less economical than condensing or low-pressure engines, because they use much more steam. When the waste steam is let out of the cylinder, the air rushes i...
-374. Installation Of Pipes
In installing pipes and metal fittings of all kinds it is absolutely necessary to make proper provision for expansion. (See Chapter IX (Heat And Expansion. 100. Generation And Movement Of Heat), Hea...
-375. Alignment Of Pipes
When pipes are not in a straight line, they are said to be out of alignment. Want of alignment sometimes causes trouble by throwing excessive strains on the flanges at the joints of stop valves, separ...
-376. Horse-Power
The power of a steam engine is commonly designated as horse-power. One horse-power is a force strong enough to raise 33,000 lbs. one foot high in one minute; this has been found to be about what a ver...
-377. Corrosion Of Pipes
If the feed water contains lime salts, a deposit will be formed in the economizer and feed connection which will more or less effectually protect the pipes from internal corrosion (rusting or eatin...
-378. Piping Material
For all ordinary and high pressures used in connection with land boilers, steel pipe is almost invariably adopted, the longitudinal joints being lap-welded. Cast steel is largely employed for bends an...
-379. Turbines
We have already seen the uses of water wheels or water turbines. Steam turbines (Fig. 171) consist of a wheel with blades. The steam, in the form of jets, strikes against the blades and moves the whee...
-380. Action Of Steam In A Turbine
In entering the turbine, steam acts in two ways, and turbines are accordingly constructed on two plans. The more important type and the only one to be described here, is the impulse turbine, in which ...
-381. Measurement Of Work In Heat Units
Experiments show that one unit of heat is equivalent to 772 ft.-lbs. of work, and when this quantity of work disappears in friction, one unit of heat is generated. Other experiments show that the unit...
-Questions 26
1. Who invented the steam engine? 2. What effect has the development of the steam engine had upon trades and industry? 3. What is a steam engine? 4. What property has steam that allows it to ...
-Chapter XXVII. Methods Of Heating. 382. Starting A Fire
In countries where the winters are cold it is necessary to devote a great deal of time and labor to the heating of dwellings. Heat is usually obtained by the? burning of wood, coal, etc. Such substanc...
-383. Methods Of Heating
Modern buildings and houses are heated by stoves, steam, hot water, or furnaces. The choice of any particular method will depend upon special conditions and requirements. Heat is given from a stove by...
-384. Steam Heating
Steam for heating (Fig. 173) is obtained from a boiler fitted with coils of pipe. As the steam passes through the radiator it gives off its heat and is condensed into water. This water flows back into...
-385. Indirect Method
The indirect method of heating (Fig. 174) is the more effective system for large buildings and schools. The heater is generally placed in a cellar or basement. The air is passed over its surface of pi...
-386. Advantages And Disadvantages Of The Indirect Method
One great advantage of the indirect system is that Fig. 173. - Steam Heating System there is always some ventilation. New air is always entering the rooms, while at the same time the older air...
-387. Exhaust Steam Heating
Exhaust steam from an engine is often used for heating. The water of condensation from an exhaust steam heating plant is frequently allowed to run to waste, but as its temperature is near boiling, coa...
-388. Low-Pressure Steam Heating
When steam at atmospheric pressure is condensed into water at a temperature of 212 F., each pound of steam gives up 966 B. T. U. of heat; but if steam of 100 lbs. gauge pressure (115 lbs. absolut...
-389. Gas For Heating Purposes
Gas, both natural and manufactured, is used extensively for heating. It burns with either a blue flame or yellow, luminous flame, depending upon the type of flame device or burner which is used. The y...
-390. Hot-Water Heating
A hot-water heating system (Fig. 175) operates by the movement of hot water from the boiler to radiators, where it gives off heat. The colder water, which has already given off its heat, returns to th...
-391. Air Circulation
The circulation and ventilation of the air in a room is necessary in any method of heating. Warmed air rises to the top of a room and the cooler air settles nearer the floor. A steam radiator warms th...
-392. Radiators And Radiation
Radiators are made up of hollow sections of cast iron. The outer surfaces are so shaped as to give the greatest possible area or, as it is generally called, the greatest radiating surface. The casting...
-393. Measurement Of Heat Radiation
The quantity of heat given off by radiators or steam pipes, in the ordinary methods of heating buildings by direct radiation, will vary from 1 3/4 to 3 heat units per hour per square foot of radiating...
-394. Main Piping
All piping must be carefully put up, and horizontal piping must have a pitch or slope of 1/4 to 1/2 in. in 10 ft., so that the water will flow out of the system as quickly as possible. A low place or ...
-395. Risers And Returns
Risers are the pipes that pass from the lower floor to the upper floors and to which the radiators are connected by short pipes or nipples. These connections must allow for expansion, and it is advisa...
-396. Steam And Air Valves
A heating system, when cold, fills with air by leakage around valve stems. This air must be allowed to escape so that steam may enter. Automatic air valves may be placed on every radiator and coil. Th...
-397. Steam Productions From Water
The weight of water required to make 1 cu. ft. of steam at any pressure is the same as the weight of 1 cu. ft. of steam. Therefore, the weight of water is obtained by multiplying the number of cubi...
-Questions 27
1. What is fuel? 2. Is a hard (dense) fuel difficult to kindle? 3. Why is it harder to light coal than wood? 4. What is smoke? 5. How is smoke removed from a fire? 6. What principle of ...
-Chapter XXVIII. Ventilation. 398. Object Of Ventilation
Ventilation is the process of removing from an enclosed space foul air, laden with impurities, and replacing it with fresh air. An exact displacement, however, does not always take place. The incoming...
-399. Methods Of Ventilation
There are three ways of removing dust and impurities from air in a building: (1) the natural method; (2) forced ventilation by means of fans, and (3) the exhaust method. Natural ventilation is prod...
-400. Waste Products
The waste products of life and industrial processes that interfere with indoor occupations are : (a) Carbon dioxide and moisture from the lungs and skins of animals. (6) The products of combusti...
-401. Perspiration
Perspiration consists of water charged with waste products. This water is evaporated from the skin by the air. If the air is saturated with moisture, as it often is during the summer, water does not e...
-402. Noxious Gases
Operatives who are exposed to irritating or poisonous gases and fumes, such as lead and its compounds, are likely to become victims of chronic poisoning. Gases that are merely irritating are of less i...
-403. Dust
In the emery, corundum, sandpaper, and allied industries, great attention is given to keeping the dust away from the mouth and nostrils of the workmen by means of hoods and exhaust fans. Oftentimes wo...
-404. Cause Of Tuberculosis
It is a well-known fact that a large percentage of deaths among factory operatives is due to consumption. While perhaps some of this may be traced to the environment of the home, many cases are contra...
-Questions 28
1. What is ventilation? 2. Why is ventilation necessary? 3. What are the different methods of ventilation? 4. Describe each method of ventilation. 5. What are the waste products of industr...
-Chapter XXIX. Gas Engines. 405. Principles On Which Based
The gas engine (Fig. 176), which is coming gradually into use, requires but a small amount of fuel. In a steam boiler, the energy is transmitted to water inside the vessel. In the gas engine, the gas ...
-406. Types Of Gas Engines
Most gas engines are of the four-cycle type used in many motor car engines. It differs from the two-cycle type, in that the explosive mixture is admitted and ignited after every other revolution of th...
-407. Operation Of Engine
The operation of a four-cycle machine may be understood by studying the four different steps in the working of the engine. There are two openings or valves in the cylinder - an inlet valve for the mix...
-408. Principal Parts Of A Motor Car
To show the works of an automobile it is necessary to remove the body or top of the car. What remains is called the chassis (Fig. 182). Starting in front of the seat we see the handle, which is a...
-409. Other Parts Of Motor Car
The other parts of an automobile which need a brief description are the starting handle, the carbureter, silencer, governor, magneto, and gears. Starting Handle. - In front of the car there is a ha...
-Questions 29
1. How does a gas engine work? 2. What is the combustible or inflammable material used? 3. What is the supporter of combustion? 4. What are the gases exploded? 5. How is gasoline made into...
-Chapter XXX. Iron And Iron Molding. 410. The Value Of The Metal Trades
Before designing and building a machine, it is necessary to know what the machine is expected to do, and the strain under which the whole machine and each part will be expected to operate. Given this ...
-411. Iron Ores
Iron, in the forms of wrought iron, cast iron, and different kinds of steel, is used in the industries and trades more than any other metal. All forms of iron arc obtained from the earth and are found...
-412. The Refining Of Iron
Since iron is found in a combined state and mixed with either sand, lime, or clay and a small percentage of manganese, phosphorus, and sulphur, it is necessary to free it of the elements with which it...
-413. Action Of The Fluxes
When the fuel is burning, a strong blast of hot air of a temperature of 1200 F. is forced through the tuyeres (pronounced tweers) at the bottom of the furnace. The blast of air acts on the burnin...
-414. Chemistry Of The Blast Furnace
The glassy slag is formed by the combination of the alumina, silica, and lime contained in the ore and flux. Being lighter than the iron, the slag floats on the molten metal and is run off near the bo...
-415. Properties Of Pig Iron
During the process of smelting, the liquid iron absorbs and combines with a considerable quantity of carbon, sulphur, silicon, phosphorus, and manganese from the ore and coke. Some of the carbon is ch...
-416. Iron Foundry
The pig iron is shipped to different foundries, where it is melted with scrap iron (old pieces of iron parts) in a furnace called a cupola. When the heating is of long duration, or when dirty or burne...
-417. Mixing The Iron
The best results for strength and elasticity are obtained by mixing a number of carefully selected kinds of iron, as such a mixture gives higher tensile strength than the average strength of the diffe...
-418. Clearing And Smoothing Castings
When iron castings are taken from the mold they present a rough surface and must be cleaned and smoothed before they can be assembled into a machine. This is done in various ways, such as by means of ...
-419. Molding
Most of the iron used in industry is made into castings. Castings are made by pouring hot molten iron into a mold, which is a body of a certain kind of sand held in a boxlike frame called a flask. The...
-421. Essentials Of Good Molding
The first essential in the process of molding is to select the proper kind of sand for the mold (Fig. 193). In selecting sand, the weight of the casting should be taken into consideration. Mold sand i...
-422. Branches Of Molding
There are three branches of molding - (1) green-sand, (2) dry-sand, and (3) loam molding. Green-sand molding involves the making of castings in molds that are composed entirely of damp sand, or tha...
-423. Green-Sand Molding
The practice of some shops embraces all three kinds of molding, but most foundries make only green-sand molds. These involve, however, more risk in making medium-sized and large castings. In many case...
-424. Brass Foundry
Brass castings are made by heating copper and zinc in pots in a furnace, and pouring the alloy into a mold. The principal differences between molds for brass and molds for iron are that brasswork mold...
-425. Properties Of Cast Iron
Cast iron has certain advantages and disadvantages as a material. It is easy to give it any desired form by molding. It resists oxidation (rust) better than either wrought iron or steel. Its compressi...
-Questions 30
1. Why is it necessary to design a machine carefully before building it? 2. What arc fergings? Why are they used? 3. What is a pattern? 4. Where is iron obtained? 5. Name some of the princ...
-Chapter XXXI. Problems In Pattern-Making. 426. Allowances For Shrinkage
All molten metal shrinks when solidifying. The amount of shrinkage varies in different metals and also in different castings of the same metal. A cylinder, for example, will shrink more in length than...
-427. Graduated Shrink Rule
A graduated rule, the purpose of which is to allow for shrinkage, is known as a shrink rule. Such rules are on sale in almost all graduations, and in one, two, and three shrinkages. ...
-428. Allowance For Finish
The allowance for finish is the amount added to a pattern to allow for machining in the machine-shop. As all castings are more or less rough when they come from the mold sand, and as they warp or spri...
-429. The Match Or Odd Side
A device to aid the mold-er to obtain quickly and easily a parting line in the mold is called a match. It supports the pattern and consists of a false part of the flask on which the drag is rammed. ...
-430. The Molding Board
Many patterns are of such an irregular shape that a straight parting line cannot be obtained while molding. In cases of this kind, the pattern is usually mounted on a molding board (sometimes called a...
-431. The Match Plate
In the molding of small castings where a great number are required, it is customary to mount several patterns on a plate called a match plate. This plate is of metal (as are also the patterns), 3/8 in...
-432. The Molding Machine
The cost of production is reduced by the use of a match plate on a machine. The rapidity with which the molds can be produced and the possibility of producing castings which require the minimum of mac...
-433. Molding In Cores
Many large castings, the patterns of which would require a great amount of material and labor, may be molded in cores. In this process no pattern is used, the practice being to make a core-box of some...
-434. Weights Of Materials And Castings
The weight of a casting may be approximately estimated from the weight of the pattern, as shown in the table below. In all cases where there are core prints or batteries to sustain the pattern, or oth...
-Questions 31
1. Is a pattern made larger than a casting? Why? 2. What is the allowance for cast iron? Is it the same for each metal? 3. Describe the steps in working a casting. 4. What is a pattern-maker'...
-Chapter XXXII. The Making And Working Of Wrought Iron. 435. Manufacture Of Wrought Iron
Wrought iron, oftentimes called bar iron, is made from the rough pig iron. In the process of manufacture, it is first refined in the puddling furnace. Here it is exposed to a very great heat, and is...
-436. The Effect Of Drawing And Rolling
When iron bars are rolled, their molecules become stretched into a fibrous condition. Rolling gives to the metal, especially when thin as in boiler plates, a greater tensile strength in the direction ...
-437. Case-Hardening
The process of hardening the surface of iron or steel is called case-hardening. The piece to be treated is first heated to a bright red and the surface rubbed with prussiate of potash. When it has coo...
-438. Characteristics Of Wrought Iron
Wrought iron possesses one of the most valuable properties of metals; small masses of it will weld or unite into one. No other metals except platinum and aluminum possess this property. If two pieces ...
-439. Malleable Cast Iron
Ordinary white cast iron can be rendered sufficiently malleable to admit of changes if heated with iron oxide. By this means the carbon in the cast iron is slowly oxidized by the oxygen in the surroun...
-440. Blacksmithing
Blacksmithing is a distinct mechanical trade, and consists of working and shaping iron and steel for ornamental, structural, and general repair work. One branch of the trade is devoted to horseshoeing...
-441. Blacksmith's Tools
The tools of the blacksmith comprise hammers of various kinds, fullers, flatters, chisels, tongs, and the hardy. The simplest and one of the most useful tools is the sledge hammer which is employed fo...
-442. Lighting The Blacksmith's Fire
To fire a forge, all clinkers are first removed and some inflammable material, such as wood shavings or oil waste, is selected and placed on the hearth over the tuyere. The fuel should be the best qua...
-443. Scarfing And Welding
The two principal operations performed by a blacksmith are scarfing and welding. The process of scarfing consists of flattening the edges of two pieces of iron preparatory to welding, so that when the...
-444. Welding Processes
There are two classes of welding - forge or pressure welding, and autogenous welding. Forge or pressure welding is applied to two pieces of metal heated to a plastic state, which are forced together b...
-445. Autogenous Welding
Autogenous welding is applied to welds which are made by heating metals to such a temperature that they will fuse together on contact, without the application of pressure. The difference between forge...
-446. Electric Arc Welding
Electric arc welding consists in joining two pieces of metal by filling in the cracks with molten metal. This is done by attaching or laying upon the steel or metal to be welded one wire of the curren...
-447. Oxyacetylene Welding
Oxyacetylene welding is one of the most practical methods of welding. The heat is derived from burning acetylene in oxygen gas. Oxyacetylene flame is also used in cutting metal. The flame actually cut...
-448. Thermit Welding
Thermit welding depends upon the chemical combination of certain substances which produce a great heat. It is particularly successful in combining broken parts of machines. The work is carried out by ...
-449. Drop Forging
The bending and shaping of large pieces of iron and steel is called drop forging. An oblong block of steel case in a steel foundry is called an ingot. As soon as the steel is set in the mold, the hot ...
-450. Steam Hammer
The steam hammer is a forge hammer consisting of a steam cylinder placed vertically over an anvil. The trip or hammer-head rises and falls by the power of steam. The trip is controlled by a lever, whi...
-451. Template
A template is a temporary pattern guide, or model by which work is marked out, or by which its accuracy is checked. Working to a template requires accuracy on the part of the operator, as the forging ...
-452. Shrunk Fits
Blacksmiths and metal-workers usually fasten one piece of metal around another by shrinking the first onto the second. This process, known as a shrink, is applied in attaching various kinds of bands, ...
-453. Allowance For Shrunk Fits
It is the practice in shrunk fits to allow 1/1000 of an inch for each inch in diameter. To illustrate: A locomotive tire 68 in. in diameter should be turned 68 X 1/1000 in., or 68/1000in., smaller ...
-454. Forced Fits
Sometimes parts are assembled in a cylindrical or slightly tapered form, and fitted under pressure. The method is called a forced fitting. An allowance of .001 or .002 is made for each inch in diamete...
-Questions 32
1. What is wrought iron? 2. How is it made? 3. What are the physical properties of wrought iron? 4. What effect has drawing and rolling on the metal? 5. What is case-hardening? Why is it d...
-Chapter XXXIII. The Making And Working Of Steel. 455. Properties Of Steel
Steel is a chemical compound of iron and carbon, but contains no carbon in the free state as cast iron does. Its tensile strength is greater than that of wrought iron and its compressive strength grea...
-456. Hardening And Tempering
The special characteristics of steel, except the very lowest grades, are that when raised to a cherry red heat and suddenly cooled, it becomes brittle and exceedingly hard; and that by subsequent heat...
-457. Tools And Tool Steel
Practically all tools are made from a selected grade of steel called crucible steel. For example, one kind of steel makes excellent razor blades, where keenness is demanded, while another is able to r...
-458. Tempering
When steel and iron are heated to a high temperature they first become red, then orange, and then white. The temperatures may be approximately told by the color as follows: First sign o...
-459. Bessemer Process
The principal grades of steel are made by the Bessemer, Siemens-Martin, and open-hearth processes. Bessemer steel is manufactured from gray pig iron, which is free from phosphorus, sulphur, and mangan...
-460. Basic Bessemer Process
A modification of the foregoing method, by which the phosphorus is removed from the iron, is known as the basic Bessemer process. Its special feature is that calcined or burnt lime is added to the cha...
-461. Siemens-Martin Steel
In the Siemens-Martin process, steel is produced either by melting a certain quantity of pig iron in the hearth of a reverberatory furnace and adding wrought iron till the bath attains the desired deg...
-462. The Open-Hearth Process
In the open-hearth process, a charge of material, consisting of wrought iron, cast iron, steel scrap, and other ores, is melted on the hearth of a reverberatory furnace and heated by gas, as in the Si...
-463. Crucible Steel
Crucible steel is made by rolling a pure grade of wrought iron into flat bars. These bars are cut up and placed in piles in a crucible with layers of pounded charcoal between them. The piles are then ...
-464. Tungsten Steel
A number of grades of steel are called alloy steels and owe their properties to the alloy which is added to them. The principal one is tungsten steel, which is made by adding ferrotungsten (an alloy o...
-465. Steel Castings
Steel castings are made by pouring mild steel into molds. Crucible steel castings are made by melting bar blister steel in crucibles and pouring it into molds. Large steel castings, such as beams for ...
-466. Mild Steel
Mild steel, a grade of steel that does not harden when heated and chilled with cold water, is made from Siemens, open-hearth, or Bessemer ingots. The ingots are heated and hammered into slabs. These s...
-467. Influence Of Impurities On Steel
Impurities, similar to those found in iron, are present in steel. Sulphur in the steel tends to make it red-short and to interfere with its welding and forging properties. Steel should not contain mor...
-468. Influence Of Nickel On Steel
Nickel gives great strength to steel, and is, consequently, widely used for shafting, rods, engines, etc. The addition of chromium to nickel steel gives an exceedingly hard steel that is used for gear...
-469. Case-Hardened Steel
Case-hardened steel is produced by placing bone-dust, specially prepared for the purpose, or burnt leather scraps in a cast iron box together with the article to be hardened. The top of the box is cov...
-470. Annealing
Of the several methods of annealing steel, the most common, when but a few pieces are to be treated, is to heat the metal red hot and then bury it in ashes, powdered charcoal, or lime. If the pieces a...
-471. An Alternative Method
Steel that is kept red hot for a long period also is materially weakened. On the other hand, its temperature must not be lowered so fast that the metal chills and hardens. The work should be left in t...
-472. Annealing Tool Steel
Often articles of tool steel which are to be threaded give trouble when machined, if annealed by either of the methods mentioned. When annealing steel for taps, extreme care must be exercised, for if ...
-473. Water Annealing
When it is necessary to anneal a piece of steel quickly, the process may be accomplished by heating it to a uniform red heat and then allowing it to cool in the air. A current of air should not be all...
-474. Test Of Steel Strength
Nitric acid will produce a black spot on steel; the darker the spot the harder the steel. Iron, on the contrary, remains bright if touched with nitric acid. Good steel in its soft state has a clean fr...
-Questions 33
1. What is steel? Give some of its general physical properties- 2. How is steel graded? What are the properties of each grade? 3. Explain the meaning of hardening; annealing; tempering. 4. Wh...
-Chapter XXXIV. Structural Steel. 475. Uses Of Structural Steel
Within the last generation, steel has been increasingly used for structural and ornamental purposes. Under the head of ornamental work comes the manufacture of inside and outside stairs, fire escapes,...
-476. Ornamental Steelwork
Before an order for a piece of ornamental steel is sent to the factory, detail drawing-are made in the drafting room and checked; they are then sent to the foreman of the ornamental department, who al...
-477. Structural Steelwork
In structural steelwork, after the draftsman has completed the detail drawings they are sent to the foreman of the structural department, who assigns the work to the layers-out. The proper I-beam or c...
-Questions 34
1. Explain the demand for structural steel. 2. Explain how structural steel is made. 3. What properties of steel and iron are utilized in structural work? 4. What fastening agents are used in...
-Chapter XXXV. Machine-Shop Practice. 478. Operations On Castings
Castings and forgings are usually taken to a machine-shop, where the surplus metal and rough parts are removed to make the castings conform to the design of the machine for which they are intended. Th...
-479. Work Of Machinists
The work of the machinist is to shape metal to a definite form, size, and finish by the use of grinding and cutting tools, and to assemble, repair, and erect machines. The metal in its original form m...
-480. Measurement Of Work
To do good work, a machine must have perfectly plane surfaces, must afford a rigid support to the tool, and must give an accurate motion to the part to be machined. There must be no slackness or backl...
-481. Micrometer
Accurate mechanical work can be done only when diameters are carefully measured. As a means to this end the micrometer caliper (Fig. 197) is employed to measure the one-thousandth or one five-thousand...
-482. Machine-Shop Tools
After the machine parts have been cleaned, the remaining operations consist of drilling holes, changing rough and uneven surfaces into smooth and plane surfaces, and so on. This work is done by chippi...
-483. Classification Of Machines
Machines may be divided into the two classes: (1) rotating machines, such as lathes, boring mills, drills, presses, milling and grinding machines; and (2) reciprocating machines, such as slotters, pla...
-484. The Cutting Capacity Of A Machine
To save expense and labor, a casting should be cut in the most economical way and in the shortest possible time. To do this, the cutting tool should attain the highest possible speed without injuring ...
-485. Theory Of Cutting Metal
A harder material will cut or scratch a softer material. Therefore the cutting tool must always be harder than the stock. Different metals, such as iron, wrought iron, steel, copper, brass, etc., poss...
-486. Kinds Of Lathes
Probably the most essential machine in the general machine-shop is the lathe. It is used for turning all cylindrical work, both straight and tapered; for boring and thread-cutting, both internal and e...
-487. Engine Lathe
An engine lathe (Fig. 198) is the commonest form of this type of machine and is used mostly for turning straight pieces. It is constructed to support a spindle which is free to revolve through the med...
-488. Engine, Turret, And Speed Lathes
The engine lathe, described above, is also used for general work, such as turning, boring, facing, reaming, and other machine operations. The turret lathe is a special machine device for the manufa...
-489. Size Of Lathe
The size of the lathe is expressed by stating the length of the bed, and the largest diameter it will swing on centers. The swing is found by measuring from the point of the head-stock center to the...
-490. Simple And Compound Lathes
A simple or single-geared lathe has a straight train of gearing from its spindle to its feed screw, with intermediate gears which serve as idlers to take up the distance between the driver and driver ...
-491. Lathe Tools
The ordinary lathe tool is a short bar or rectangular cross-section of tool steel with a cutting edge at one end. It is produced by forging and grinding. It must be hardened and tempered to cut the me...
-492. Vise
The machinist's vise is one of the simplest as well as one of the most important parts of the machineshop outfit. Its mechanical principle is based on that of the screw. Much of the success of the wor...
-493. Screw Machine
The screw machine is practically the same as the turret lathe, but is used for different purposes; in fact, the screw machine when first designed had a turret, the tools of which were advanced in the ...
-494. Drilling
A different cutting speed is necessary for nearly every material, and drills are constructed so as to meet the various requirements. A large drill must run slower than a small one, the turns per minut...
-495. Shaper
Shapers and planers are used for finishing plane surfaces. The shaper is a small machine on which light work is fastened to the bed or held in a planer chuck. The tool is held in a tool post at the en...
-496. Planer
A planer works on the same principle as the shaper, the shaft to which the tight pulley is fastened being geared to the platen or table so that the table runs back and forth. The work is fastened to t...
-497. The Operations Of Planing
The planer is one of the heaviest of machine tools. Planing is rough and heavy work, and rigid construction and stiffness are needed to take the heavy cuts, as the surfaces of castings and heavy forg-...
-498. Shaping Machine
The shaping machine differs from the planer in that the tool post moves while the work is stationary. Both machines are used for planing flat, level, and oval surfaces but the shaper is nicely adapted...
-499. Key-Way Machine
The key-way machine is used for the purpose of cutting a slot or a key-way in any thick piece of metal, such as a pulley. The machine is not complicated and its operation requires very little skill. A...
-500. Drilling Machines
Probably the first power machine that every machinist runs is the drilling machine or drill press. Sometimes it is simply called the drill, although this term usually refers to the small drill that ac...
-501. Milling Machines
The milling machine (Fig. 199) is not so generally used as its worth merits, because comparatively few machinists know how to operate it. This machine is not limited to plane milling, but will mill ir...
-502. Power Press
The power press is used for cutting and forming sheet-metal parts. It has a strong base supporting a crank shaft, which converts the rotary motion imparted by the pulley or fly-wheel into the rectilin...
-503. Grinding Machines
Universal grinding machines (Fig. 200) are used for grinding pieces which have been distorted by hardening, although it is sometimes profitable to finish soft pieces also by this method. This machine ...
-504. Power Hammer
Power hammers may be divided into three classes: (1) trip hammers, (2) friction board or drop hammers, and (3) steam hammers. In all classes, dies are used to shape or form the hot metal. Trip hammers...
-505. The Vernier And Its Use
An important measuring instrument used in machine operation is the vernier (Fig. 201), so called from the inventor's name. It consists of a bar of metal divided into inches, each inch being again d...
-506. Thickness Gauge
The thickness of metal may be determined by means of a thickness gauge, which consists of many levers, varying in thickness by thousandths of an inch, and each designated by a number. By applying thes...
-507. Screw Pitch Gauge
It is very desirable at times to be able to tell quickly the pitch of a screw thread. This may be done by means of a screw pitch gauge, which consists of many thin pieces or leaves of steel fastened t...
-508. Division Of Machine-Shop Trades
The machine trade is divided into machine construction, tool-making, and die-sinking. Under the first type of work are grouped all those operations, discussed in previous sections, which have to do wi...
-Questions 35
1. Explain the different steps in finishing and machining castings. 2. How are the castings made to exact size? 3. What is high-speed steel? Why is it very useful in the machinists' trade? 4....
-Chapter XXXVI. Sheet Metals. 509. Nature Of Work
Formerly the workman who made household utensils out of tin was called a tinsmith. Nowadays the use of tin for this purpose has greatly decreased, and aluminum and enamel ware has taken its place to a...
-510. Common Sheet Metals
Certain metals and alloys, such as brass, copper, lead, tin, zinc, tinned iron (tin-plate), aluminum, and thin sheet iron, possess strength, durability, lightness, and a clean, smooth surface. Most of...
-511. Smelting Of Copper
There are two methods of obtaining copper - by smelting and by electrolysis. It is desirable to mix different ores so that they will be in proper condition for smelting, as one often acts as a flux to...
-512. Copper Refining By Electrolysis
Pure copper is obtained by means of electrolysis.* Bars of impure copper are melted in an ordinary furnace and are granulated by being placed on a copper tray at the bottom of a tank of cold water. Th...
-513. Physical Properties Of Copper
Copper when pure is of a red color, exceedingly malleable and ductile. When rolled, hammered, or worked into sheets, it is used to a great extent for roofing and sheathing vessels, and for making cyli...
-514. Chemical Properties
When a piece of copper is heated in the air it combines slowly with the oxygen and two oxides are formed: cuprous oxide (Cu20) and cupric oxide (CuO). The cuprous oxide is red and the cupric oxide is ...
-515. Properties Of Aluminum
Aluminum resembles silver in its whiteness but is much lighter. The ore of this metal is obtained from pure clay, a substance with which man was familiar for ages without suspecting the treasure it co...
-516. Aluminum Alloys
Aluminum is used to make alloys of various kinds, the most important of which is aluminum bronze. This alloy is made up of from 5 to 8% aluminum and from 92 to 95% copper. It is used to imitate gold, ...
-517. Uses Of Tin
Tin is obtained from the ore oxide of tin by smelting. Because of its high price and its low tensile strength (about two tons per square inch), tin is comparatively little used. As one of the constitu...
-518. Uses And Chemical Properties Of Lead
Lead is seldom found in a pure state, but usually as the carbonate (PbC03), the sulphate (PbS04), or the sulphide galena (PbS). To obtain lead it is necessary to free the ore of its combining elements...
-519. Alloys Of Lead
Oftentimes it is necessary to use an alloy which will expand on cooling. Such an alloy is obtained by melting together 9 lbs. of lead, 2 lbs. of antimony, and 1 lb. of bismuth. The alloy is used to fa...
-520. Properties Of Zinc
Zinc is a bluish white metal which has only lately been discovered in its pure form, though its ores have long been known and used. It is obtained from the ores in the following manner: Zinc carbon...
-521. Use Of Zinc
Zinc is used with copper to form brass and other alloys, and as a covering to protect iron from the action of the atmosphere or of sea water. By placing blocks of zinc in metallic contact with the iro...
-522. Chemical Characteristics Of Zinc
Air attacks zinc very slowly and even the pressure of moisture forms only a basic carbonate which acts as a protective coating. Consequently, only the outer layer is affected. When heated, zinc burns ...
-523. Properties Of Mercury
Mercury, also called quicksilver because it looks like silver and flows quickly, is the only metal that is liquid at an ordinary temperature. Small drops of pure mercury are sometimes found, but it is...
-524. Uses Of Mercury
Mercury is much used for making thermometers and barometers. It is also used for extracting gold and silver from their ores, by allowing the crushed ore to flow in a thin mud over plates covered with ...
-525. Properties Of Platinum
Platinum is a metal discovered only in the eighteenth century. The principal supply comes from South America and Russia. It is as durable as gold, as hard as iron, resembles silver in color, and is ex...
-526. Properties Of Antimony
Antimony is a hard metal used as an alloy with tin and lead for various purposes where great hardness and durability are needed. Printers' type metal, which must be firm enough to bear the pressure of...
-527. Bismuth
Bismuth has a reddish white metallic luster, and is found as a pure metal, or in compounds as a sulphide. The ore is first roasted to oxidize the arsenic and sulphur, and is then mixed with carbon and...
-528. Brass
Brass is an alloy of copper and zinc. The malleability and ductility of this alloy depend upon the amount of copper in the mixture. The ordinary yellow brass of commerce, known as high brass because i...
-629. Anneals And Tempers Of Sheet Metals
Sheet metals are used to meet definite conditions and are softened or hardened accordingly. The degree of softness is expressed as anneal and the degree of hardness as temper. Therefore in describin...
-530. Extended Metal Shapes
There are many brass and bronze alloys that may be made into irregular shaped bars by forcing the hot metal through dies of the required shape. These bars are spoken of as extended metal. ...
-531. German Silver
German silver is an alloy of nickel, copper, and zinc. Its quality is designated by figures which indicate the percentage of nickel in the mixture. It is called white metal when containing 18% or more...
-532. Kinds Of Bronzes
In the early days of manufacture the term bronze was applied to a non-corrosive metal made of a mixture of copper and tin, dark in color, hard in temper, and of high tensile strength. Today bronze ref...
-533. Gun-Metal
Gun-metal is an alloy of copper and tin, with sometimes a small proportion of zinc. It is a harder metal than either of its constituents and has a greater density. It is more fusible and less likely t...
-534. Nickel
Nickel is a hard, white metal, more nearly resembling silver than tin and is used because of its luster and permanence. Dilute sulphuric and hydrochloric acid affect it only slightly, but nitric acid ...
-535. Bronzing
Bronzing is an attempt to produce the effect of bronze on other metals or substances. A solution of sal ammoniac and salt Of sorrel in vinegar is used for metals, while a composition of yellow ocher, ...
-536. Bell-Metal
Bell-metal is a compound of tin and copper, which becomes not only more sonorous, but heavier than either of the separate ingredients which compose it. While the proportions of tin and copper in the c...
-537. Britannia Metal
Britannia is an alloy metal composed of block tin, a small portion of antimony, and less than one-third as much copper as brass. This compound which is bright and silvery looking, is now extensively u...
-538. Arsenic
Arsenic is used in many metallic alloys, Its various oxides are important ingredients in different dyes. It is employed as a flux for glass, and it produces many kinds of coloring in glass. It is a vi...
-539. Pewter
Pewter is a dull looking alloy formerly-used for making plates and dishes, beer measures, wine measures, and large vessels. Good hard pewter is made of tin, copper, and antimony, but a very inferior k...
-540. Common Solder And Fluxes
Solder is an alloy used to stick metals together. It is a mixture of lead and tin usually in the proportion of half and half. Many other solders are used in soldering gold, silver, German silver, and ...
-541. Process Of Soldering
Soldering or sweating is a difficult operation. Careful investigations show that as much as 90% of the soldering work done is defective. This trouble is due principally to improper and careless clea...
-542. Aluminum Solder
Aluminum solder consists of aluminum, phosphor-tin, zinc, antimony, and an acid. In forming the solder, the zinc, tin, and antimony should be melted before the acid is added. The following flux should...
-543. Brazing Metals
The flanges and fittings for copper pipes are made of an alloy of 84% copper and 3% zinc, called brazing metal. Brazing solder must contain more zinc than tin in order to have the solder fuse before t...
-544. Shears For Cutting Metals
Since sheet metals come into the trades in flat sheets, shears for cutting these sheets have been devised. There are two kinds of shears, namely, a power shear for cutting out edge lines, and a machin...
-Questions 36
1. What is sheet-metal work? 2. Explain the difference between the work of the coppersmith and the sheet-metal worker. 3. What are some of the metals used for sheet-metal work? Why are these par...
-Chapter XXXVII. Plumbing And Water Supply. 546. Relation Of Plumbing To The Water Supply
In large communities where people live close together, pipes for conducting water and sewerage must be installed. To make installations intelligently so as to have enough water for household use, fire...
-546. Rivers And Lakes
A river usually begins with a small stream in the hills and represents the drainage of the rain, ice, or snow that falls there. If there is a growth of trees on the hills, the roots of the trees tend ...
-547. Wells
In small communities the householder usually receives his supply of water from a well near the house. To understand how a well obtains its water, it is necessary to recall what has been said concernin...
-548. City Waterworks
A large community cannot use wells to advantage because of the danger of contamination. Therefore, it is necessary to secure water from a distance and allow it to flow to the community. It is therefor...
-549. Faucet
The faucet consists of a bar handle which operates a screw. The screw raises or closes a disk to which a leather washer is attached. If it closes the disk, the water is prevented from running through ...
-550. Water Hammer
Water under pressure in pipes is subject to the force of gravity in the same manner as a body falling through the air. To illustrate: When water flowing through a pipe is suddenly checked, a noise is ...
-551. Water Meter
When the public realize that water is measured, the consumption is less per capita (per person) than when it is not measured. Therefore, within the last few years drinking water has been metered in ma...
-552. Sewerage
The disposal of waste water and sewerage is a very important question. In the country, where houses are not thickly settled, the waste water is allowed to drain into the ground. The sewerage is dispos...
-553. Traps
In large communities where houses are quite close together, the sewerage and waste water is disposed of by being allowed to flow into an outlet pipe, called a drain pipe. The drain pipe flows into a l...
-554. Work Of The Plumber
A plumber's work consists of the installation of fixtures for gas, water, sewerage, and drainage purposes; the setting up in buildings and residences of plumbing fixtures and their appurtenances, such...
-555. Plumbers' Tools
The tools most commonly used by plumbers are as follows: the shave hook, for cleaning the tarnish from pipe in preparation for wiping the joint; the ladle, for handling molten lead; the cloths, for wi...
-556. Joints
The joints most commonly used by plumbers are the wiped and screw joints. The wiped joint is made by scraping and fitting the parts together and then pouring molten solder upon the place of joining. T...
-557. Cement
Plumbers use a mixture of one part Portland cement and two parts clean sand over a ring of oakum in making joints on earthenware house sewers. * Oakum is prepared from old ropes, untwisted, loosene...
-Questions 37
1. Describe the importance of plumbing. 2. State the advantages of a good water supply. 3. Name the different sources of water supply. 4. How does water reach a well? 5. Describe a water s...









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