102 Steam Engineering 684. Mention another safety device connected with hydraulic elevators. Ans. Safety clamps under the control of a speed limit centrifugal governor which causes the clamps to grip the guides and thus hold the car. 685. How is this safety governor operated ? Ans. By means of a small cable connected with the car and moving with it, which passes over the sheave pulley of the governor. 686. Why are some elevator pistons fitted with two pis- ton rods? Ans. To prevent the piston, and crosshead from turn- ing or twisting, and also to strengthen the construction. 687. What other methods are used for manipulating the water valve, besides the one already described? Ans. Running ropes, and standing ropes, either of which may be operated by means of a lever, or wheel in the car. 688. Do these devices directly operate the main valve? Ans. No. They operate a small valve called the pilot valve. 689. What is the function of the pilot valve? Ans. When opened it admits the pressure water to a small cylinder with piston connected to the main valve stem. This actuates the main valve, which in turn, by its movement, closes the pilot valve. 690. Upon what does the amount of opening given the pilot valve, and consequently the main valve depend? Ans. Upon the distance the lever in the car is moved from central position. 691. What is meant by central position of lever? Elevators Electric and Hydraulic 103 Ans. That position in which there is no flow of water either into or out of the cylinder, and the car is moving only by its momentum. 692. What is the result of moving the lever too quickly to central position when the car is moving at a high rate of speed? Ans. The motion of the car will be arrested with a sudden jerk. 693. How many kinds of horizontal hydraulic elevators are in use? Ans. Two. One is the pushing, and the other the pulling type. 694. Describe the action of the pushing type? Ans. The car being at the bottom, the pressure water is admitted behind the piston which then moves, pushing the crosshead and cable sheave and lifting the car. 695. Describe the action of the pulling type? Ans. It is the opposite of that just described. 696. Is there much difference in the valve mechanism of the horizontal, and vertical types of hydraulic elevators ? Ans. Very little except a few minor details. 697. "What is meant by a double-deck machine? Ans. Where the floor space is restricted two, and some- times three or four machines are mounted one above the other. 698. What water pressure is usually carried in operat- ing the types of hydraulic elevators that have hitherto been described? Ans. Pressures not exceeding 200 Ibs., the average being 150 Ibs. per square inch. 699. Are any higher pressures than this being used for operating hydraulic elevators? Ans. Yes. Pressures of 700 to 800 Ibs. and higher. SWINGLE'S CATECHISM OF STEAM, GAS, AND ELECTRIC ENGINEERING A complete Practical System of Instruction covering all the important details relative to the care and operation of Steam Boilers, Steam Engines, Steam Turbines, Air Compressors, Refrigerating Machinery, Elevators both Electric and Hydraulic, also Electric Machinery, in- cluding Dynamos, Motors, Transformers, Rotary Con- verters, Switch Boards, etc. Especially valuable to those contemplating an ap- pearance before an Examining Board of Engineers A Complete Book of Reference for the Working Engineer in the daily round of his duties. BY CALVIN F. SWINGLE Author of "Twentieth Century Hand Book for Steam Engineers and Electricians," "Encyclopedia of Engineering," and "Steam Turbine Engines." CHICAGO FREDERICK J. DRAKE & COMPANY PUBLISHERS COPYRIGHT 1910 BY FREDERICK J. DRAKE & Co. Swingle's Catechism of Steam, Gas, and Electrical Engineering INTRODUCTION The constantly increasing demand for information in a condensed form, pertaining to engineering topics has in- duced the author to prepare this book, with a view of assisting his brother engineers in their search for just the information that they are looking for, and especially when they are in a hurry, and do not have much time to look for it, as, for instance, in an emergency due to a break- down, the Catechism of Steam, Gas, and Electricity will be found to be an invaluable aid, for the reason that it covers practically the entire field of Stationary Engineering, in- cluding not only Steam Boilers and Engines, but, in addi- tion, Steam Turbines, Gas Engines, and Gas Producers, Air Compressors, Refrigeration and Ice Making, Elevators, both Electric and Hydraulic, and finally, 'the subjects of Electricity and Electric Machines, Dynamos, Motors, etc. The necessity for thorough and complete examinations regarding the qualifications of men asking to be entrusted with the care and operation of power generators, whether steam, gas or electrical, is now universally recognized, and as a consequence, all large cities and towns, and a large number of states, have license laws, requiring engineers and electricians to pass these examinations before being granted license permitting them to take charge of and operate such 217105 Introduction machinery. To those contemplating the taking of such ex- aminations, the questions and answers following will prove to be a most valuable helper, as it furnishes the much sought-f or information in plain, easily understood language, the answers being condensed in such form as to enable the applicant for license to memorize them without, any diffi- culty whatever, and thus be .able to qualify himself for the position sought for. This Catechism thus serves the double purpose of being an assistant to the working engineer, and also a helper to the man who aspires to become an engineer. CALVIN F. SWINGLE. Types of Boilers 1. What types of boilers are most commonly used for stationary work? Ans. The horizontal tubular boiler and the water-tube boiler. 2. Describe in general terms the horizontal tubular boiler. Ans. It consists of a shell having tubes of small diam- eter, extending from head to head. These tubes are located in the water space. 3. What is their function? Ans. To supply a passageway to the stack for the hot gases from the furnace. 4. Does the water in the boiler receive heat from these tubes? Ans, It certainly does. 5. Describe the route taken by the smoke and hot gases in the operation of a tubular boiler. Ans. From the furnace, located under the front end of the boiler, the gases pass under and along the sides of the shell, back to the rear end, the upper part of which is arched over. The route is here reversed, and the products of combustion return through the flues towards the front end and thence through the breeching into the stack. 6. Is this type of boiler economical in the burning of fuel? Ans. It can be made so if properly set and handled in operation. 7. Describe in a general way the water-tube boiler. Ans. It consists of a set, or sets of tubes 3 to 4 inches in diameter, sometimes vertical, and sometimes inclined, 5 6 Steam Engineering and connected at the top to a steam drum, and at the bot- tom to a mud drum. 8. What advantages as regards circulation of the water has the water tube boiler? Ans. It provides for a free circulation. 9. Name another advantage connected with the water tube boiler. Ans. The margin of safety from dangerous explosions, 10. Why is this? Ans. Because if one or more tubes gives way the pres- sure is relieved. 11. What precautions should be observed in the design and construction of a boiler? Ans. The best materials should be used, the boiler should be simple in design, and the workmanship should be perfect. 12. Where should the mud drum be located ? Ans. In a place removed from the action of the fire. 13. What should be the capacity of the boiler relative to its work? Ans. It should have a steam and water capacity suf- ficient to prevent any fluctuation in either the steam pres- sure, or the water level, if properly fed. 14. Why should the water in a boiler circulate freely and constantly? Ans. In order to maintain all parts at as near the same temperature as possible. 15. What should the strength of a boiler be, relative to the strain it is liable to be subject to? Ans. It should have a great excess of strength, 16. Is a combustion chamber an advantage to a boiler? Types of Boilers 7 Ans. It is, in order to complete the combustion of the gases before they escape to the chimney. 17. How should a boiler be arranged with regard to cleaning ? Ans. All parts should be easily accessible for cleaning and repairs. 18. What type of boiler is the Cahall? Ans. It is a water-tube boiler. 19. Is it vertical or horizontal? 4ns. It is built either way. 20. What form of Cahall is generally used in central power stations? Ans. The horizontal form. 20a. What is the range of pressures that these boilers are built for? Ans. From 160 to 500 pounds per square inch, 21. Describe the method of constructing the joints. Ans. The sheets are beveled on the edges, bent into shape, and rivet holes drilled after bending. 22. What is gained by so doing? Ans. Absolutely round rivet holes and no crystalliza- tion. 23. What type of riveted joint is usei on the higher pressure boilers? Ans. Triple riveted, double strapped. 24. How are the tubes connected to the steam drum in the Cahall boiler? Ans. By nipples connected to saddles on the drum. 25. Does this boiler rest upon the brick work? Ans. It does not, but is suspended free from the ma- sonry. 26. What advantage is there in this style of setting? 8 Steam Engineering Ans. The entire structure is free to expand or contract without causing any strains on either boiler or brick work. 27. Describe the Heine boiler. Ans. It consists of one, and sometimes two shells on drums resting upon water legs riveted to each end. These water legs are connected by horizontal tubes. The water fills the tubes, water legs, and partially fills the shell, leav- ing the upper portion for steam space. 28. In the setting does this boiler occupy a horizontal position ? Ans. No. The shell and tubes have an incline of one inch in twelve from front to rear. 29. What provision is made for cleaning and repairing the tubes ? Ans. Hand-holes are located in the head plates oppo- site each tube. 30. How are these hand-holes closed? Ans. In the ordinary way, by plates. 31. Where is the mud drum located in the Heine boiler ? Ans. Inside the shell, near the bottom. 32. How is the Heine boiler supported in the setting? Ans. The front or fixed end rests upon cast iron col- umns. The rear water leg upon rollers. 33. Describe in brief the Babcock & Wileox boiler. Ans. It is composed of wrought iron tubes, placed in an inclined position, and connected with each other, and with a horizontal steam, and water drum by vertical headers. 34. Where is the mud drum in this boiler ? Ans. In the rear, and connected to the lowest part of the boiler. 35. What provision is made for cleaning the tubes in the Babcock & Wilcox boiler? Types of Boilers 9 Ans. Through hand-holes in the headers, opposite each tube. 36. How is this boiler supported in the setting? Ans. It is suspended from wrought iron girders, en- tirely independent of the brick work. 37. Describe in general terms the Stirling boiler, Ans. It consists of three upper steam drums, each be- ing connected by a number of tubes to a lower or mud drum. 38. How are the steam spaces connected? Ans. By shorter tubes. 39. How is the boiler supported? Ans. On a structural steel frame work. 40. What provision is made for expansion and contrac- tion of the tubes ? Ans. They are slightly curved near the ends. 41. How are the hot gases directed in their course from furnace to stack? Ans. By means of fire brick baffle walls. 42. How is the interior of this boiler cleaned? Ans. Four manholes are provided in the drums, by which access to the interior of both the drums and tubes is obtained. 43. What type of boiler is the Maxim boiler? Ans. It is a water-tube boiler consisting of two drums, one above the other, connected by tubes. 44. Describe the tubes. Ans. Each tube has two bends, thus providing for un- equal expansion or contraction. 45. How is the heating surface of the Maxim boiler arranged ? 10 Steam Engineering Ans. It is so arranged that the current of heated gases is made to travel three times the length of the tubes, the direction of the current heing changed seven times in its route from furnace to stack. 46. What can be said of the Bigelow-Hornsby water- tube boiler? Ans. wing to the flexible form of its construction it is possible to build it in very large units, 2,000 horsepower and upwards. 47. What peculiar feature makes this possible? Ans. Each section is independent of its neighbor, ex- cept the nipples connecting with the steam drum, and the equalizing nipples connecting the bottom drums of the rear sections. 48. How is the boiler supported ? Ans. Entirely from overhead beams, 49. What percentage of the heating surface do the tubes of the front unit comprise? Ans. More than 12 per cent. 50. Where is the feed water first admitted? Ans. Into the bottom drum of the rear unit. 51. Describe the course of the feed water. Ans. The feed water is admitted into the bottom drum of the rear unit, and is advanced gradually from the coldest to the hottest portion of the boiler. 52. How is the speed of the feed water up the rear unit regulated ? Ans. By the amount of steam generated, ample time being permitted for scale forming matter to be deposited in the bottom drum of this unit. 53. Where does the liberation of steam take place ? Ans. In the upper drum. Types of Boilers 11 54. What can be said of this boiler regarding the utili- zation of the heat? Ans, It is baffled so that the products of combustion are carried uniformly over the heating surfaces in thin layers, the baffle plates serving to guide the gases through in substantially uniform passages. 55. To what factor of safety is the Bigelow-Hornsby boiler built? Ans. Five for 200 pounds working pressure. 56. Describe in brief the Wickes vertical water-tube boiler. Ans. It consists of two cylinders joined together end- ways by straight tubes, and erected in a vertical position. 57. What can be said of the top cylinder? Ans. It is the longer, and is designated the steam drum. 58. What about the bottom cylinder? Ans. It is the shorter, and is designated the mud drum. Both cylinders vary in dimensions as to diameter and length, according to the power required of the boiler. 59. Where are the manholes of the Wickes boiler ? Ans. One is placed in the convex head of the steam drum; there are also a number of hand-holes in this head. A manhole is also placed in the lower or mud drum, near the floor, thus permitting access to the top and bottom of the boiler, 60. How are these tubes divided? Ans. By heavy fire-clay tile these tubes are divided into two compartments. Those tubes in the front compart- ment are called the "risers" and those in the rear the "downcomers." 61. What can be said of the heat in its double passage? 12 Steam Engineering Ans. It surrounds completely, and closely the tubes in both compartments. 62. Where is the water line in this boiler? Ans. At a sufficient height in the steam drum to in- sure the complete submersion of all the tubes. 63. How is the brick work setting of the Wickes water- tube boiler arranged? Ans. It is independent of the weight of the boiler, and free to expand or contract. 64. Describe briefly the design of the Atlas water-tube boiler. Ans. It consists mainly of three drums and two water legs extending crosswise, while the tubes extend lengthwise. 65. What is the original feature in the design of the water legs? Ans. They are formed by the continuation of front and rear shell plates. 66. What other valuable feature is claimed for this boiler? Ans. After the steam leaves the vessels containing water it is passed through a series of superheating tubes, and is superheated. 67. Describe the course of the feed water. Ans. It is fed first into the purifier, whence it over- flows into the rear drum and down into the rear leg, thence through the inclined tubes to the front leg, thence up into the front drum, where the steam is liberated and carried through superheating tubes to the steam drum. 68. What are the facilities for cleaning the water tubes of this boiler? Ans. An individual hand-hole is located opposite each end of each water tube. Types of Boilers 13 69. How is the interior of each of the three cross drums reached ? Ans. Through a large manhole in each end. 70. Describe briefly the design and construction of the Marzolf water-tube boiler. Ans. It consists of three drums connected with each other in triangular form. Drum A directly over the fire is connected by tubes with drum B above it, and with drum C in the rear and slightly below it. Drum C, which is the mud drum, is also connected with drum B. The tubes are each slightly bent. The steam is collected in drum B, which is maintained about one-third full of water. 71. Describe in brief the action of the heat upon this boiler. Ans. It acts first upon the water in drum A over the furnace, then by means of a baffle wall it is carried along the inclined tubes to drum B, where it is deflected and car- ried down along other inclined tubes to drum C, thence to the stack. 71. How are the products of combustion caused to act upon the lower bank of tubes? Ans. By means of baffle walls located in the rear of the furnace. 72. At what point in this boiler is the feed water ad- mitted? Ans. At the lowest point, viz., the mud drum. 73. What are the principal advantages claimed for the Duplex water-tube boiler? Ans. Delivery of superheated steam; the removal of steam from the boiler at a point where there is no ebul- lition; the drums not exposed to the direct action of the fire. 14 Steam Engineering 74. Describe in brief the design of this boiler. Ans. Two upper steam drums connected by tubes, a mud drum at the bottom and rear which is connected to the upper drums by headers and short nipples. The tubes are inclined 20 degrees to insure rapid and positive cir- culation. 75. How is this boiler supported? Ans. Upon a heavy steel framework. 76. What is the leading feature in connection with the Erie City water-tube boiler? Ans. The three banks of tubes are practically vertical, connected to upper, and lower drums, and spaced so that any one of them may be cut out for repairs without interfering with the others. 77. How do the products of combustion act upon this boiler? Ans. The baffling is arranged to pass three times across the tubes, and at each end of the upper drum is a dry chamber. 78. Describe in brief the best method of supporting horizontal tubular boilers. Ans. By means of hangers suspended from I beams, supported by cast iron columns. This takes the weight off the side walls. 79. What three principles should govern the design and construction of steam boilers? Ans. First: They should be absolutely safe. Second: They should be economical in the consumption of fuel. Third: They should be capable of furnishing dry steam. 80. What is meant by the term tensile strength as ap- plied to boiler material ? Types of Boilers 15 Ans. The number of pounds of pull that would be required to break a bar of the material in the direction of its length. 81. What is liable to occur in case the tensile strength is too high ? Ans. Cracking of the sheets, also certain changes in the physical properties of the metal. 82. Which are the stronger, punched or drilled plates? Ans. If the material is good soft steel, punched plates show a greater shearing resistance. 83. What should be the tensile strength of rivet iron? Ans. About 60,000 pounds per square inch. 84. What is a good test for a %-inch rivet? Ans. It should stand being doubled up and hammered together cold without being fractured. 85. What is the shearing resistance of iron rivets ? Ans. About 85 per cent of the original bar. 86. What is the shearing resistance of steel rivets? Ans. 77 per cent of the original bar. 87. What is meant by efficiency of the joint? Ans. The percentage of strength of the ttolid plate, that is retained in the joint. 88. What should be the style of joint with sheets thicker than % inch? Ans. It should be a double butt joint. 89. What should be the ratio of diameter of rivet to thickness of plate for double butt joints? Ans. The diameter of the rivet should be about 1.8 times the thickness of sheet. 90. What should be the pitch of rivets? 16 Steam Engineering Ans. Three and one-half to four times the diameter of the hole. 91. Describe the triple riveted butt joint. Ans. It has two welts or straps, one inside, and one outside. 92. Is this a good form of joint? Ans. It is. 93. What type of joint gives the highest efficiency ? Ans. A joint in which the tensile strength of the rods from which the rivets are cut approaches that of the plates, and when the proportions of the joint are such, that the tensile strength of the rivets, and the crushing resistance of the rivets and plate, for a given, or unit strip, are as nearly equal as it is possible to make them. 94. In how many ways may failure occur in a double riveted butt joint? Ans. In five distinct ways. 95. Name the first manner of failure. Ans. Tearing of the plate at outer row of rivets. 96. What is the second? Ans. Shearing two rivets in double shear, and one in single shear. 97. What is the third manner of failure? Ans. Tearing of the plate at inner row of rivets, and shearing one rivet in the outer row. 98. Describe the fourth method of failure. Ans. Crushing in front of three rivets. 99. What is the fifth manner of failure? Ans. Crushing in front of two rivets, and shearing one. 100. How may a triple riveted butt joint fail? Types of Boilers 17 Ans. First: By tearing the plate at the outer row of rivets. Second: By shearing four rivets in double shear, and one in single shear. Third: Eupture of the plate at the middle row of rivets, and shearing one rivet. Fourth : Crushing in front of four rivets, and shearing one rivet. 101. What is the efficiency of the quadruple riveted butt joint? Ans. In some cases as high as 94 per cent. 102. In what four ways may failure occur in this type of joint? Ans. First: By tearing the plate at the outer row of rivets. Second: By shearing eight rivets in double shear, and three in single shear. Third : By tearing at inner row of rivets, and shearing three rivets. Fourth : By tearing at first outer row of rivets where the pitch is 7% inches. 103. What is implied in the staying of a flat surface? Ans. Holding it against pressure at a series of isolated points, which are arranged in symmetrical order. 104. Does the cylindrical shell of a boiler need bracing? Ans. No. 105. Why is this? Ans. Because the internal pressure tends to keep it cylindrical. 106. How are the heads sometimes stayed? Ans. By through stay rods of soft steel, or iron 1% or 2 inches in diameter extending through from head to head. 107. What advantage has this form of stays? Ans. The pull is at right angles to the plate. 108. What other methods of bracing the heads of high pressure boilers are used? Ans. Gusset stays, and dished heads. 18 Steam Engineering 109. What is the minimum factor of safety for stays, and braces? Ans. Eight. 110. Give a simple rule for finding the bursting pres- sure of unstayed flat surfaces. Ans. Multiply the thickness of the plate in inches by ten times the tensile strength and divide the product by the area of the surface in square inches. OF THE \ UNIVERSITY 1 OF Boiler Setting and Equipment 111. What two methods of support are generally used in the setting of horizontal tubular boilers ? Ans. First: By suspension from I beams and girders, and secondly by means of brackets riveted to the side sheets, and resting upon the side walls. 112. How are water tube boilers usually supported in the setting? Ans. By suspension. 113. What important details should be looked after concerning the brick work? Ans. The foundations should be good, and the walls built in such manner as to take care of the expansion and contraction. 114. How is this accomplished? Ans. By leaving an air space of two inches in the side and rear walls beginning at the level of the grate bars, and extending up to about the center line of the boiler. 115. What kind of brick should be used for inside lining? Ans. Fire brick of good quality. 116. How should bridge walls be built for horizontal tubular boilers? Ans. Straight across from wall to wall. 117. About what distance from the bottom of the boiler should this wall be ? Ans. Eight to ten inches. 19 20 Steam Engineering 118. Where is the combustion chamber? Ans. It is the space back of the bridge wall. 119. How should boiler walls be secured? Ans. By means of tie rods extending the entire length, and breadth of the setting. 120. What are the buck stays? Ans. They are strong cast-iron, or wrought-iron bars placed vertically upon the outside of the walls, and secured to the tie rods. 121. Should horizontal tubular boilers be set perfectly level lengthwise? Ans. It is better that they be set about one inch lower at the back end, than at the front end. 122. Give one of the main reasons for this style of setting. Ans. When washing out the boiler, the mud and water will more easily drain towards the blow off pipe. 123. What is the usual ratio of grate surface to heating surface ? Ans, One square foot of grate surface to each 36 square feet of heating surface. 124. At what point should the glass water-gauge be located? Ans. In such a position as to bring the lowest visible portion of the gauge glass exactly on a level with the top of the upper row of tubes of a horizontal tubular boiler. With other types of boilers the lowest end of the gauge glass should always be on a level with the danger point. 125. Why sHould the above rules be observed in locating a water column ? Boiler Setting and Equipment 21 Ans. Because when the water level in the glass begins to draw near to the lower end of glass the engineer or water tender will have an infallible guide to warn him to get busy. 126. "What is a good indication that the connections of the water glass are choked or plugged with scale ? Ans. When there is no movement of the water in the glass. 127. Why should there be a trap, or siphon in the pipe connecting the steam gauge to the boiler? Ans. To prevent the hot steam from coming into con- tact with the spring of the gauge. 128. How may the steam gauge, and safety valve be tested in comparison with each other? Ans. By occasionally raising the steam pressure high enough to cause the valve to open at the point for which it is set to blow. 129. Is the pop valve reliable as a safety valve ? Ans. It. is, if not allowed to stand idle too long and become rusty, 130. How often should it be allowed to blow off? Ans. At least twice a week. 131. Are lever safety valves used to any extent? Ans. They are still in use to some extent, but are rapidly being superseded by pop valves. 132. What is the function of a fusible plug? Ans. The fusible alloy of which it is composed will melt when it comes in contact with dry steam, and allow the steam to blow a warning. 133. Where is the fusible plug located? 22 Steam Engineering Ans. In that portion of the heating surface of a boiler which is first liable to be overheated from lack of water. 134. Are Domes and Mud drums necessary parts of boilers ? Ans. They are not as a rule. 135. Where should the blow off pipe always be con- nected? Ans. With the lowest part of the water space. 136. Should the blow off cock be opened while the boiler is under pressure? Ans. Yes, for a few seconds, once, or twice each day. 137. Is a surface blow off any advantage? Ans. It is, especially if the water is muddy. 138. What precautions should be observed with regard to inlet for feed water? Ans. The feed water should not be allowed to come directly in contact with the hot boiler sheets until its temperature is equal to, or near that of the water within the boiler. 139. How may this be brought about? Ans. By means of feed water heaters, and internal coils of pipe through which the feed water is caused to pass. 140. What is the most economical style of feed pump? Ans. The belt-driven power pump. 141. Is it the most reliable, or safest? Ans. It is not. 142. What is the most reliable boiler feeding device, for all conditions of stationary practice? Ans. The double acting steam pump. Boiler Setting and Equipment 23 143. What precautions should be observed in figuring on the capacity of a feed pump for a battery of two or more boilers? *',*>-> *- Ans. To take into account the total quantity of water required by all of the boilers; and let the capacity of the pump be equal to it. 144. In connection with feed apparatus for boilers, what other fittings and devices should be installed? Ans. There should be a tee located in the horizontal section of the feed pipe near the check valve, and between it and the feed pump. One opening of this tee, is to be re- duced to % or % inch to receive a hot water thermometer for testing the temperature of the feed water when making evaporative tests, etc. 145. What other provisions along this line should be made? Ans. Tanks for weighing the feed water also a sep- arate feed pipe to the boiler under test, also means for weighing the coal burned during test. 146. Is the injector an efficient boiler feetier? Ans. It is in locations where there is not very much exhaust steam available for heating the feed water. 147. When, and by whom was the injector invented ? Ans. In the year 1858, by Henri Giffard. 148. Why does an injector force water into a boiler that is under steam pressure? Ans. Because the steam passing through the injector imparts sufficient velocity to the water to overcome the boiler pressure. 149. Why does an injector lift water from a lower level ? Ans. Because the condensation of the steam in the com bining tube creates a vacuum there, and in the suctioi pipe connected with it. 150. How may the size of the steam header for a batter} of boilers be determined? Ans. The sectional area of the header should equal 01 slightly exceed the sum of the areas of all the boiler outlets to be connected with it. 151. Where should all connections except for drainage, enter, and leave the main header? Ans. At the top. 152. How many valves should there be in each boiler connection leading to the header ? Ans. Never less than two. 153. What kind of valves are best for this purpose? Ans. Automatic stop, and check valves. 154. What is the most efficient type of superheater for practical purposes? Ans. The one that is contained within the boiler setting. 155. How is the velocity of flow, or piston speed per minute of a pump ascertained? Ans. Multiply number of strokes per minute by length of stroke in feet, or fractions thereof. 156. The piston speed being known, how is the velocity of flow in the discharge pipe found ? Ans. The velocity of flow in the discharge pipe is in inverse ratio to the squares of the diameters of the pipe and the water cylinder of pump. 157. When it is required to discharge a certain quantity of water from a given size of pipe in a given time, how may the velocity of flow in feet per minute be found ? Boiler Setting and Equipment 25 Ans. Multiply the number of cubic feet to be discharged by 144 and divide by area of pipe in inches. 158. When the volume of water to be discharged and the velocity of flow are known, how is the area of the pipe obtained ? Ans. Multiply volume in cubic feet by 144, and divide by velocity in feet per minute. 159. What is meant by "acceleration of gravity," and what constant number represents it in connection with hydraulics ? Ans. Acceleration of gravity is the increase in velocity caused by the actual weight of the water, and is represented by the constant 32. 160. What per cent of allowance is ordinarily made for friction in water pipes? Ans. A deduction of 25 per cent is sufficient. Feed Water Heaters 161. Is a feed water heater an economical factor in the equipment of a boiler plant? Ans. It certainly is, provided exhaust steam is used for heating. 162. How many kinds of exhaust heaters are there? Ans. Two, viz.: Open, and closed. 163. Describe in brief terms the action of a so-called open heater. Ans. The exhaust steam mingles directly with the water, and a portion of it is condensed. 164. Describe the operation of a closed heater. Ans. The exhaust steam and the water are kept sep- arate. In some cases the steam passes through tubes that are surrounded by water, and in other types the water fills the tubes that are surrounded by steam. 165. What difference exists between the two kinds of heater? Ans. The closed heater is under full boiler pressure when the feed pump is working, while the open heater is not because the feed pump is between it and the boiler. 166. What per cent of saving in fuel may be effected by the use of a heater? Ans. Prom 12 to 15 per cent. 167. Of what capacity should a feed water heater be, relative to the boilers ? Ans. It should have capacity sufficient to supply the boilers for 15 or 20 minutes. 27 28 Steam Engineering 168. Can the exhaust injector be used for feeding boilers. Ans. It can if the boiler pressure does not exceed 75 pounds. 169. What advantages are gained by the use of mechan- ical stokers? Ans. Regulation of the supply of fuel to meet the de- mand for steam; also the opening and closing of furnace doors is avoided. 170. What are the disadvantages attending the use of mechanical stokers? Ans. First, cost of installation. Second, in case of a sudden demand for steam the mechanical stoker cannot re- spond as quickly as in hand firing. Third, extra cost for power to operate them. 171. Into how many classes are mechanical stokers grouped ? Ans. Four. 172. Enumerate, and briefly describe. Ans. Class one An endless chain of short grate bars that travel horizontally over sprocket wheels. Class two Grate bars similar to the ordinary type hav- ing a continuous motion up and down, or forward and back, the bars being either horizontal or slightly inclined. Class three Grate bars steeply inclined and having a slow motion. Class four Under feed stoker in which the coal is pushed up onto the grate by means of a revolving screw, or steam ram. 173. In what three forms is mechanical draft used for boilers. Feed Water Heaters 29 Ans. First Induced draft. Second Forced draft, in which fans force air beneath the grates. Third A combination of induced and forced draft. 174. Is a good draft necessary for the efficient opera- tion of steam boilers? Ans. It certainly is. The economical combustion of fuel cannot be accomplished without a good draft. 175. For what two purposes are chimneys required? Ans. First, to carry of! obnoxious gases. Second, to create sufficient draft for the combustion of the fuel. 176. What factor governs the intensity of the draft, ndependent of the dimensions of the chimney? Ans. The difference in weight of the outside and in- side columns of air. 177. What is the best shape of chimney? r Ans. Round, with a straight flue. 178. What is the weight, and volume of air at a tem- perature of 60, and uader average atmospheric pressure it sea level? Ans. One cubic foot weighs 536 grains, and 13.06 cubic feet weigh one pound. Care and Operation of Boilers 179. What is one of the most important duties of the engineer when he goes on watch ? Ans. To ascertain the exact height of the water in his boilers. 180. Describe the correct method of doing this. Ans. Open the valve in the drain pipe of the water col- umn, and allow the water to blow out freely for a few seconds, then close the valve and note the level of the water when it settles back in the gauge glass. 181. What is the next important step in beginning the day's work ? Ans. To see that the fires are cleaned, and in good con- dition. 182. In firing boilers by hand, what is the first and most important rule to be observed? Ans. Keep a clean fire. 183. What is the second rule? Ans. See that every square inch of grate surface is covered with a good live fire. 184. Give the third rule regarding firing by hand. Ans. Keep a level fire. 185. What is the fourth rule? Ans. When cleaning the fire, always clean all clinkers and dead ashes away from the back end of the grates and the bridge wall. 31 32 Steam Engineering 186. Why should this be done? Ans. In order to allow a free passage of the air through the grate bars, so as to promote combustion. 187. If the plant runs continuously, day and night, what is one of the important duties of the fireman coming off watch? Ans. To leave clean fires, clean ash pits, and a good supply of coal ready for the oncoming force. 188. How long a time should the fires be allowed to burn before cleaning? Ans. This depends upon the quality of the coal. With a coal that does not clinker on the grate bars, an interval of 7 or 8 hours may elapse between cleanings, but with the average soft coal the fires should not be allowed to burn longer than 4 or 5 hours without cleaning. 189. What is one of the greatest aids to good combustion in a hand-fed furnace? Ans. A clean bridge wall, kept as hot as possible 190. What precautions should be observed regarding the depth of the fire? Ans. It should not be allowed to become so deep and heavy as to prevent the air from passing up through it freely. 191. How should the position of the ash-pit doors be regulated ? Ans. With a clean, light fire, a slight opening will be sufficient, but with a heavy fire, and the grates clogged with ashes, a larger opening is necessary. 192. How can the best results be secured in firing bituminous coal ? Ans. By leaving the fire doors slightly open for a few seconds immediately after throwing in a fire. Care and Operation of Boilers 33 193. What reason is there for doing this? Ans. Because the volatile matter in the coal flashes into flame the instant it comes in contact with the heat of the furnace, and unless there is sufficient supply of oxygen present just then, the combustion will be imperfect. 194. What is the result of this imperfect combustion? Ans. The formation of carbonic oxide gas, and the con- sequent loss of about two-thirds of the heat units contained in the coal. 195. How may this loss be prevented in a great meas- ure? Ans. By admitting a sufficient volume of air, either through the fire doors, directly after throwing in a fresh fire, or, better still, providing air ducts through the bridge wall, or side walls, which will direct the air in on top of the fire. 196. How much air is required for the complete com- bustion of one pound of coal? Ans. By weight 12 pounds by volume 150 cubic feet. 197. What precaution is necessary regarding the tubes of a boiler in order to get the best results from the fuel ? Ans. The tubes should be kept clean and free from soot and scale. 198. Should the steam jet cleaner be depended upon alone for cleaning the tubes? Ans. No. The scraper should also be used. 199. How should safety valves be looked after? Ans. They should be ample in size, never overloaded, and should be tested at least once a day to see that they act freely. 34 Steam Engineering 200. At what point should the steam gauge pointer stand when the pressure is off? Ans. It should stand at zero. 201. What should be done in case of low water in a boiler? Ans. The fire should be covered immediately with ashes, earth, or if neither is available use fresh coal. Draw the fire as soon as it can be done without increasing the heat. 202. Should the rate of feeding the water be increased, in case of extremely low water in the boiler? Ans. It should not, neither should the engine be stopped or the safety valve lifted, until the fires are out, and the boiler cooled down. 203. In case of indications of cracks or blisters appear- ng^n the boiler sheets, what should be done ? Ans. There should be no delay in making repairs. 204. What should be done with fusible plugs when used ? Ans. They should be cleaned and carefully scraped on both water and fire sides at each washing out. 205. How may the most economical results regarding fuel be attained with a steam boiler? Ans. By keeping the heating surfaces clean, both inside and outside, also careful firing, a little at a time, but keep- ing the grates covered. 206. Should cold water ever be fed into a boiler when it is under pressure? Ans. Not when it can be avoided. 207. How may foaming usually be stopped? Ans. By checking the outflow of steam, by blowing down and pumping up, or by checking the draft and fires. 208. Should air be allowed to pass to the boiler or tubes, except through the furnace ? Care and Operation of Boilers 35 Ans. It should not, as it will cause a waste of fuel. 209. What should be done with leaks when discovered? Ans. They should be repaired as soon as possible. 210. What precautions should be observed when pre- paring to empty a boiler for washing out, or other pur- poses ? Ans. Allow it to cool down until there is no steam pres- sure, and until the brick work is cool also. 211. When firing up a boiler what course should be pursued ? Ans. Steam should be raised very slowly, and rapid fir- ing avoided. 212. What bad results follow too rapid firing up of a boiler? Ans. Straining of the joints and seams caused by un- equal expansion. 213. What should be done with a boiler that is to stand idle for any length of time? Ans. It should be emptied, and thoroughly dried. In case this is impracticable, fill it full of water, and put in a quantity of washing soda. 214. How long a time may a boiler be safely operated between dates of washing out ? Ans. This depends upon the nature of the feed water. The time should never be longer than two weeks, and with very bad water, the boiler should be washed out once a week. 215. Besides cleaning the boiler inside, what other very important work should the boiler washer perform while inside the boiler? 36 Steam Engineering Ans. He should closely examine all braces, stays, and rivets by tapping them with a hammer. Any loose or de- fective parts can usually be detected in this way. 216. Describe four ways in which tube failures may occur. Ans. 1. Pitting. 2. Defective welds. 3. Bagging. 4. Scabbing and blistering. 217. How may a great saving in fuel be effected with regard to the feed water ? Ans. By heating it with the exhaust steam from engines and pumps before passing it to the boilers. 218. Describe the available heating surface of a station- ary boiler, of either type, return tubular or water tube. Ans. The lower half of the shell, and heads, and the combined cross sectional area of all the tubes. 219. What should be the location of the water gauge glass, relative to the water level in the boiler? Ans. It should be located at such a height as to bring the lower end of the glass tube on a level with the danger point for low water in the boiler. 220. Where should the lower gauge cock be located relative to the danger point? Ans. About three inches above. 222. Should an engineer or water tender depend entirely upon the water gauge glasses ? Ans. He should not, but should frequently open and try the gauge cocks. 223. What should be done with the entire water column several times a day? Ans. It should be blown out thoroughly. 224. What should be done with the safety valves in order to make them reliable ? Care and Operation of Boilers 37 Ans. They should be allowed to blow off at least twice a week. 225. Why is this necessary? Ans. Because the valves are liable to become corroded, and stick to their seats if not attended to properly. 226. What is the rule for finding the bursting pressure of boilers? Ans. Multiply the tensile strength by the thickness and divide by one-half the diameter of the shell. 227. How may the safe working pressure of a boiler be ascertained ? Ans. By dividing the bursting pressure by five. 228. What is the rule for ascertaining the velocity of flow in a pump? Ans. Multiply the number of strokes per minute by length of stroke in feet. This will give piston speed. 229. How may velocity of flow in the discharge pipe of a pump be found ? Ans. Divide square of diameter of water piston by the square of the diameter of pipe, and multiply by piston speed per minute. 230. What is the rule for finding velocity in feet per minute required to discharge a given quantity of water in a given time ? Ans. Multiply number of cubic feet to be discharged by 144 and divide by area of pipe in inches. 231. When the volume and velocity of water to be dis- charged are known, how may the area of the pipe be ascer- tained? Ans. Multiply volume in cubic feet by 144 and divide by velocity in feet per minute. 38 Steam Engineering 232. What is one of the main requisites in the success- ful burning of coal in a boiler furnace? Ans. A good draft. 233. What is a common cause of lost economy in the operation of boilers? Ans. Air leaks in the brick settings. 234. Mention another source of loss in connection with mechanical stokers. Ans. The dead area of grate that is covered with a thin layer of clinker, and ash. 235. What is meant by the expression "priming?" Ans. Carrying over into the cylinder of water in tKc form of fine spray mingled with the steam. 236. How may this be prevented to a large extent ? Ans. By placing a baffle plate in the steam space of the boiler, directly under the dome. Steam separators may also be employed for this purpose. 237. What should be the principal object in view in burning coal under a boiler? Ans. To transfer as many as possible of the total heat units in the coal, to the water in the boiler. Combustion, Heat 238. What is meant by the term combustion as used in steam engineering? Ans. It is the rapid chemical combination of oxygen with the carbon, hydrogen and sulphur in the fuel with the accompaniment of heat and light. 239. What is meant by the symbol C0 2 ? Ans. CO 2 represents perfect combustion, viz., the cre- ation of carbon dioxide. 240. What is the most abundant combustible in nature? Ans. Carbon. 241. How many heat units are contained in one pound of pure carbon? Ans. 14,500. 242. What is the heating value of one T>ound of hydro- gen gas? Ans. 62,000. 243. Give the composition of coal. Ans. Fixed carbon, volatile matter, ash and sulphur in various proportions, depending upon the quality of the coal. 244. Is sulphur desirable as a constituent of coal? Ans. It is not. The gases formed from its combustion attack the metal of the boiler, causing corrosion. 245. What office does nitrogen perform in combustion? 39 40 Steam Engineering Ans. No useful office. Rather it is a detriment, and in fact is the chief source of loss in furnaces. It is drawn in with the air. 246. What is meant by the term calorific value of fuel ? Ans. The amount of heat liberated per pound of fuel undergoing perfect combustion. 248. What are economizers in connection with a boiler plant? Ans. Coils or stacks of cast iron pipe placed within the smoke flue, or breeching and surrounded by the hot gases while the water is passed through the pipes on its way to the boilers, thus receiving an additional amount of heat. 249. What two factors are necessary in order to attain economy in the burning of coal? Ans. A constant high furnace temperature and quick combustion. 250. Define the term heat. Ans. Heat is the result of the vibration of the mole- cules or atoms composing matter. 251. Upon what does the intensity of heat depend? Ans. Upon the rapidity of the agitation to which the molecules are subject. 252. What are the general effects of heat? Ans. When heat is added to, or taken away from a body the temperature of the body is altered and its volume is varied. 253. What is absolute zero? Ans. It is that degree of temperature at which, owing to the intense cold, a perfect gas would disappear. Abso- lute zero is 461 below the zero of the Fahrenheit ther- mometer. Combustion, Heat 41 254. What is a heat unit (B. T. U.) ? A ns. It is the quantity of heat required to raise the tem- perature of one pound of water one degree, or from 39 to 40 F. 255. What is the mechanical equivalent of heat? Ans. 778 foot pounds; in other words, 778 pounds raised one foot high. 256. What is the specific heat of any substance? Ans. The ratio of the quantity of heat required to raise a given weight of that substance one degree in tempera- ture, to the quantity of heat required to raise an equal weight of water one degree when the water is at its maxi- mum density, viz., 39.1 F. 257. What is latent heat? Ans. Heat given to a body and not warming it. 258. What is sensible heat? Ans. Heat given to a body and warming it. 259. Of what is pure water composed? Ans. By volume Hydrogen 2 parts, oxygen 1. By weight Hydrogen 11.1 parts, oxygen 88.9. 260. Is perfectly pure water desirable for use in a steam boiler? Ans. It is not, as it will cause corrosion and pitting of the sheets. 261. What two ingredients in water are the chief causes of incrustation in boilers? Ans. The carbonates of lime and magnesia. 262. What is steam? Ans. Steam is the vapor of water generated by an in- crease of the natural vibrations of molecules of the water through the application of heat. 42 Steam Engineering 263. What is saturated steam? Ans. Steam taken directly from the boiler to the engine without being superheated. 264. What is superheated steam? Ans. Steam that has been heated to a higher tempera- ture than that due to its pressure. 265. What should be done with all pipes through which, live steam is conducted for purposes of heating, or power? Ans. They should be well protected by a covering, in order to prevent loss of heat by radiation. 266. In what respect should steam be considered in its relation to the engine? Ans. As a vehicle for transferring the heat energy from the boiler to the engine. Evaporation Tests 267. What is the primary object of an evaporation test? Ans. To ascertain how many pounds of water the boilers are evaporating per pound of coal burned. 268. What other important points relative to boiler operation may be determined by these tests? Ans. There are four. First To determine the efficiency of the plant as an apparatus for the consumption of fuel, and the evaporation of water. Second To determine the relative economy of different varieties of coal, and other fuels. Third To determine whether or not the boilers are being operated as economically as they might be. Fourth To determine whether the boilers are being over worked. 269. In what condition should the testing apparatus be maintained? In first-class condition, ready to be used at any time for making a test. 270. What should be done with the boiler, and all of its appurtenances preparatory to making a test? Ans. They should be put in good condition, by clean- ing, etc. 271. How should the boiler under test be operated during the test? Ans. At its full capacity. 272. Where should the water level be at the beginning, and close of the test? 43 44 Steam Engineering Ans. At the height ordinarily carried, and its position should be marked by tying a cord around one of the guard rods of the gauge glass. 273. How long should the test last? Ans. About 10 hours. 274. How is the percentage of moisture in the steam determined ? Ans. By means of the calorimeter. 275. How many, and what kind of calorimeters are used for this purpose? Ans. Two. The throttling calorimeter, and separating calorimeter. 276. Upon what principle does the throttling calori- meter act? Ans. Upon the principle of temperatures. 277. How does the separating calorimeter act ? Ans. It mechanically separates the water from a known volume of steam passing through it. 278. In what other manner may the condition of steam regarding its dryness be approximated? Ans. By observing its appearance as it issues from a pet cock, or other small opening. 279. How will steam containing 1 or 2 per cent of moisture appear under such conditions ? Ans. It will be transparent close to the orifice from which it issues. 280. How is the chimney draft measured? Ans. By means of a draft gauge. 281. What is the usual form of draft gauge? Ans. A glass tube bent in the shape of the letter U. 282. Describe the action of a draft gauge. Evaporation Tests 45 Ans. One leg of the U tube is connected to the chimney by a small rubber hose. The other leg is open to the at- mosphere. The tube is partly filled with water, which when there is no draft will stand at the same height in both legs. 283. When there is a draft and the rubber hose is con- nected to the chimney how is the water in the U tube affected? Ans. The draft suction causes the water in the leg to which the hose is connected, to rise while the level of the water in the other leg will be equally depressed. 284. How is the intensity of the draft thus estimated ? Ans. In fractions of an inch, .5, .7 or .75 inches. 285. "What is the object of flue gas analysis ? Ans. There are three. First To determine the amount of excess air admitted to the furnace. Second To de- termine the character of the combustion. Third To as- certain the heat losses. 286. What weight of oxygen is required for the com- plete combustion of one pound of carbon? Ans. 2.67 pounds. By volume, 32 cubic feet. 287. What gaseous combination is produced by com- plete combustion? Ans. Carbon dioxide (C0 2 ). 288. What is the result of imperfect combustion? Ans. Carbon monoxide (CO). 289. How is the efficiency of the boiler and furnace ascertained through an evaporation test? Ans. By weighing the coal consumed and the water evaporated during a certain number of hours and dividing the number of pounds of water evaporated by the number of pounds of coal consumed. This will give number of pounds water evaporated per pound of coal. 46 Steam Engineering 290. What is meant by the term "equivalent evapora- tion ?" Ans. It assumes that the feed water enters the boiler at a temperature of 212, and is evaporated into steam at 212 and at atmospheric pressure. 291. Why is this standard necessary in evaporation tests? Ans. Because of the variations in the temperature of the feed water used in different tests. 292. What is meant by boiler horse-power? Ans. The evaporation of 34% pounds water from a feed temperature of 212 into steam of the same tempera- ture; or the evaporation of 30 pounds water from a feed temperature of 100 into steam at 70 pounds gauge pres- sure. 293. What is meant by the expression "total heat of evaporation ?" Ans. The sum of the sensible heat plus the latent heat, at boiling point. 294. What is steam in its relation to the engine? Ans. It is merely a vehicle for transferring the heat energy from the boiler to the engine shaft. Steam Engines 295. Into what two general classes are steam engines divided. Ans. Simple and compound. 296. Describe a simple engine. Ans. A simple engine may be either condensing or non- condensing, but its leading characteristic is, that the steam is used in but one cylinder. 297. What is a condensing engine? Ans. One in which the exhaust steam is passed into an air-tight vessel in which a vacuum is maintained, the ex- haust steam being there condensed by coming in contact with cold water, or a series of tubes through which cold water is being circulated. 298. Describe a compound engine? Ans. A compound engine is one in which the steam is made to do work in two or more cylinders before it is al- lowed to exhaust. 299. How is this accomplished? Ans. By causing the exhaust steam from the first, or high pressure cylinder, to pass into a second cylinder of larger diameter, and, if the engine be triple or quadruple expansion, from thence into a third or fourth cylinder, the diameters of which increase in regular ratio. 300. What is a non-condensing engine? Ans. One from which the steam exhausts directly into the atmosphere, or is used for heating purposes before passing out into the open air. 47 48 Steam Engineering 301. What disadvantage does a non-condensing engine constantly labor under? Ans. The pressure of the atmosphere amounting to 14.7 pounds per square inch is constantly in resistance to the motion of the piston. 302. Mention several other causes that tend to increase the back pressure upon the piston of a non-condensing en- gine. Ans. The resistance of bends and turns in the exhaust pipe, also causing the exhaust to pass through feed water heaters or heating coils. 304. What is back pressure? Ans. Pressure that tends to retard the forward stroke of the piston. 305. What advantage has a condensing engine over a non-condensing engine? Ans. The atmospheric pressure is removed from in front of the piston to a degree corresponding to the height of the vacuum that is maintained in the condenser. 306. How many classes of condensers are there in gen- eral use? Ans. Two ; jet condensers and surface condensers. 307. Describe a jet condenser. Ans. One in which the steam is exhausted into an air- tight vessel, and is there condensed by coming in contact with a jet or spray of cold water. 308. How is this water removed? Ans. By means of the air pump, which also maintains a vacuum in the condenser. 309. Describe a surface condenser. Steam Engines 49 Ans. It is an air-tight vessel, either cylindrical or rectangular in shape, fitted with a large number of brass or copper tubes, of small diameter, through which the cold water is forced by the circulating pump. A vacuum is maintained in the body of the condenser by the air pump, and the steam exhausted into this is condensed by coming in contact with the cool surface of the tubes. In some cases the steam passes through the tubes in place of around them, the condensing water being forced into and through the body of the condenser, and the vacuum being main- tained in the tubes. 310. Describe an injector condenser. Ans. A condenser in which the cold water is forced through an annular enlargement of the exhaust pipe, and passing down into a nozzle which gradually contracts. The exhaust steam entering at the same time is condensed, the water rushing through the nozzle with a velocity sufficient to create a vacuum. 311. About what quantity of water is .required per horse-power per hour to condense the exhaust steam from an engine? Ans. About 38 to 40 gallons, depending upon the tem- perature of the condensing water. 312. What three factors are necessary to insure good economy with multiple cylinder engines? Ans. First A high initial pressure. Second Expan- sion of the steam to greatest extent possible. Third Pro- tecting the surfaces of the cylinders from cooling influences. 313. Describe a cross compound engine. Ans. An engine consisting of two cylinders, each hav- ing its own connecting rod and crank, the cranks being set at opopsite ends of the engine shaft, and at an angle 60 Steam Engineering of 90 to each other. The high pressure cylinder exhausts into the low pressure cylinder, usually through a receiver. 314. Describe a tandem compound engine. Ans. An engine having the two cylinders arranged tan- dem to each other, with a common piston rod, and connect- ing rod. 315. What advantage is gained by this design? Ans. A much shorter and more direct route for the exhaust steam in its passage from the high to the low pres- sure cylinder. Valves and Valve Setting 316. What inportant features in the operation of an engine are dependent upon a correct adjustment of the valves ? Ans. The efficiency of the engine, the economical use of steam, and the regular and quiet action of the engine. 317. How many different types of valves are there in general use? Ans. Slide, poppet, rotative, piston, gridiron, etc. 318. What are the basic principles governing the ad- justment of the valves of an engine, regardless of the type? Ans. Admission, cut-off, release, and exhaust closure; each of these functions to occur at the proper moment dur- ing one stroke of the piston. 319. Name two important functions of a valve. Ans. Lap and lead. 320. What is the effect of increasing outside lap ? Ans. Later admission, and an earlier cut off. 321. What results from increasing inside lap? Ans. Earlier exhaust closure, and an increased conpres- sion. 322. What advantage has an engine of the four valve type over a single valve engine ? Ans. Each individual valve may be adjusted in- pendenfly of the others. 323. If a valve had neither lap nor lead what would be the position of the eccentric relative to the crank? 51 52 Steam Engineering Ans. 90 ahead of the crank. 324. What is meant by the term "angular advance," and why is it necessary ? Ans. The distance that the high point of the eccentric is set ahead of a line at right angles with the crank. It ia necessary in order to give the valve lap, and lead. 325. What is the first function of the valve at the com- mencement of the stroke ? Ans. Lead, or admission. 326. What is the second function? Ans. Full port opening. 327. What is the travel of a valve equal to? Ans. Twice the port opening plus twice the outside lap. 328. What is the third function of the valve? Ans. Cut off. 329. What is the fourth function? Ans. Exhaust closure, or compression. 330. What will be the effect if the valve has no inside lap? Ans. An early release, and no compression. 331. What is meant by "radius of eccentricity ?" Ans. One half the travel of the valve. 332. What is an eccentric? Ans. A mechanical device for converting rotary into reciprocating motion. Its center of revolution is apart from its center of formation. 333. What is the "throw" of an eccentric? Ans. The distance from the center of the eccentric to the center of the shaft. 334. What is meant by eccentric position? Valves and Valve Setting 53 Ans. The location of the highest point of the eccentric relative to the center of the crank pin, expressed in degrees. 335. What is valve travel? Ans. The distance covered by the valve in its move- ment. 336. What is lap? Ans. The amount that the ends of the valve project over the edges of the ports when the valve is at mid travel. 337. What is inside lap? Ans. The lap of the inside, or exhaust edge of the valve over the inside edge of the port. 338. What is outside lap? Ans. The lap of the outside edge of the valve over the outside edge of the port. 339. What is lead? Ans. The amount that the port is open when the crank is on the dead center. 340. Why must a valve have outside lap? Ans. Because admission and cut off are controlled thereby. 341. Why should a valve have inside lap ? Ans. In order that release and compression may be properly controlled. 342. What is the effect of decreasing the angular ad- vance ? Ans. All the important functions of the valve occur later. 343. What results follow from decreasing the travel of the valve? Ans. Less lead, a later admission and release, and an earlier cut off and compression. 344. What is meant by automatic or variable cut off? 54 . Steam Engineering Ans. A system in which full boiler pressure is constantly maintained in the valve chest, the speed being regulated by the governor controlling the point of cut ofi. 345. What is meant by fixed cut off? Ans. When the point of cut off remains the same, re- gardless of the load, the speed being regulated by throttling the steam. 346. What three changes must be made in order to cause an earlier cut off on an engine that has a fixed cut off? Ans. First Increase the angular advance. Second Increase the outside lap. Third Increase the inside lap. 347. What is the first step in valve setting? Ans. To place the engine on the dead center. 348. What is meant by the dead center? Ans. When the piston is at the end of the stroke, and the centers of the crank shaft, crank pin, and cross head pin are in line. 349. What rule should be observed in turning an en- gine to place it on the dead center? Ans. Always turn it in the direction in which it is to run. 350. Why is this necessary? Ans. In order to guard against errors which might result from lost motion in the parts. 351. Having placed the engine on the dead center, what is to be done next? Ans. Adjust the eccentric rod to the proper length? 352. What should be done with the valve before con- necting it with the eccentric rod ? Ans. It should be placed at mid travel, and marked. ', Valves and Valve Setting 55 353. What is necessary before the valve can be placed in its central position? Ans. The exact amount of outside lap must be known. 354. What amount of lead is usually given to the valve ? Ans. From -fa in. to % in. depending upon the size of the engine. 355. What is the function of the governor? Ans. To properly regulate the speed of the engine. 356. Explain the action of a governor? Ans. Its action is based upon the principle of the cen- trifugal, and centripetal forces, which cause the balls or weights attached to the arms, to fly outward or inward as their speed of revolution increases or decreases. 357. In what manner is this movement of the balls caused to regulate the speed? Ans. In the pendulum or fly ball governor, the motion is transferred by means of levers and rods to the cut ofl mechanism. In the shaft governor the changes in the position of the weights change the angular advance of the eccentric, thus causing an earlier or later cut off, according as the load is light, or heavy. 358. In what way does the throttling governor regulate the speed of an engine? Ans. It controls the position of a valve in the steam pipe, opening or closing it according as the engine needs more, or less steam to maintain a regular speed. 359. What is compression? Ans. If the exhaust port is closed by the valve, just be- fore the piston reaches the end of stroke, a portion of the steam will be entrapped in the cylinder, and being ahead of the piston will be compressed. 360. Is there any advantage in this? 56 -JSteam Engineering ^H Ans. Yes. The steam thus compressed acts as a cush- ion for the piston, preventing shock or jar to the moving parts on reaching the end of the stroke. 361. What is an adjustable cut off? Ans. One in which the point of cut off may be adjusted by a hand wheel attached to the valve stem of a throttling governor. Definitions 362. What is absolute pressure? Ans. Pressure reckoned from a perfect vacuum. 363. What is gauge pressure? Ans. Pressure above atmospheric pressure. 364. What is initial pressure? Ans. Pressure in the cylinder at the beginning of the stroke. 365. What is terminal pressure? Ans. Pressure in the cylinder at the end of the stroke. 366. What is mean effective pressure (M. E. P.) ? Ans. The average pressure acting upon the piston throughout the stroke. 367. What is back pressure? Ans. Pressure tending to retard the forward stroke of the piston. 368. What is absolute back pressure? Ans. Back pressure measured from a perfect vacuum. 369. What is the ratio of expansion? Ans. The relative volume of steam in the cylinder at point of release, compared to volume at cut off. 370. What is wire drawing of steam ? Ans. Eestricted passage of the steam caused by too small a steam pipe. 371. What is condenser pressure? Ans. Pressure existing in the condenser caused by the lack of vacuum. 57 58 Steam Engineering 372. What is vacuum? Ans. That condition existing within a closed vessel from which all matter, including air has been expelled. 373. What is absolute zero? Ans. 461.2 below zero Fahr. 374. What is piston displacement? Ans. The space swept through by the piston in a single stroke. 375. What is piston clearance? Ans. The distance between the piston and cylinder head at the end of the stroke. 376. What is steam clearance? Ans. The distance between the piston at end of stroke, and the valve face. 377. What is a horse power (H. P.) ? Ans. 33,000 Ibs. raised one foot in one minute of time. 378. What is indicated horse power (I. H. P.) ? Ans. The horse power as shown by the indicator dia- gram. 379. What is piston speed? Ans. The distance in feet traveled by the piston in one minute. 380. Give the rule for figuring the horse power? Ans. Area of piston in square inchesXM. E. P.Xpiston speed-f-33,000. 381. What is net horse power? Ans. I. H. P. minus engine friction. 382. Define Boyle's law of expanding gases? Ans. Pressure at constant temperature varies inversely as the space it occupies. 383. What is an adiabatic curve? Definitions 59 Ans. The curve of expanding gas that loses no heat while expanding. 384. What is an isothermal curve ? Ans. The curve of an expanding gas of constant tem- perature, but influenced by moisture. 385. What is an expansion curve? Ans. The curve traced upon the diagram by the indi- cator pencil. 386. Define the first law of thermodynamics. Ans. Heat and mechanical energy are mutually con- vertible. 387. What is power? Ans. The rate of doing work. 388. What is the unit of work? Ans. The foot pound, viz., the raising of one pound, one foot high. 389. Define the first law of motion? Ans. All bodies continue either in a state of rest, or of uniform motion in a straight line, unless compelled by im- pressed forces to change that state. 390. What is work, mechanically considered? Ans. PressureX distance passed throughXtime. 391. What is momentum? Ans. MassX density. 392. What is dynamics? Ans. The science of moving powers. 393. What is force? Ans. That which alters the motion of a body, or puts in motion a body that was at rest. 394. Define the maximum theoretical duty of steam? Ans. Mechanical equivalent of heat X total heat units in a pound of steam? 60 Steam Engineering 395. How may steam efficiency be expressed ? Ans. Heat converted into useful work-f-heat expended. 396. How may engine efficiency be expressed ? Ans. Heat converted into useful work-r-total heat re- ceived in the steam. 397. How may efficiency of the plant be expressed? Ans. Heat converted into useful work-f-calorific or heat value of the fuel. 398. What is horse power constant ? Ans. The power the engine would develop with one pound M. E. P. 399. What is meant by steam consumption per H. P. per hour? Ans. Weight in pounds of steam used-^H. P. developed. 400. What are ordinates as applied to indicator dia- grams? Ans. Parallel lines drawn at equal distances across the face of the diagram, perpendicular to atmospheric line. Indicator 401. What two important points are gained by the use of the indicator? Ans. First It shows the average pressure upon the piston throughout the stroke. Second It shows the action of the valve or valves in admission, cut ofi and release of the steam. 402. What is the first principle of the indicator? Ans. Pressure of the steam in the engine cylinder dur- ing an entire revolution, against a small piston in the cylin- der of the indicator. 403. What resistance is in front of the indicator piston ? Ans. A spiral spring of known tension. 404. What is the second principle of the indicator? Ans. By means of a multiplying mechanism of levers, the stroke of the indicator piston is communicated to a pencil moving in a straight line. 405. What is the third principle of the indicator? Ans. By means of a reducing mechanism and cord, the motion of the engine piston during an entire revolution is imparted to a small rotating drum, to which is attached a piece of blank paper. 406. How is a diagram obtained? Ans. The pencil is held against the paper and thus traces a diagram of the action of the steam within the engine cylinder. 407. What is the atmospheric line? 61 62 Steam Engineering Ans. A line drawn by the indicator pencil before com- munication is established between engine cylinder and indi- cator cylinder. 408. Where should a diagram from a non-condensing engine appear relative to the atmospheric line? Ans. It should appear above the atmospheric line. 409. Where should the diagram from a condensing en- gine appear? Ans. Partly above, and partly below the atmospheric line. 410. What is the best reducing motion to use? Ans. The reducing wheel. 411. How is the indicator attached to the engine cylin- der? Ans. By means of half-inch pipe tapped into the side of the cylinder near the ends. 412. How are the springs numbered? Ans. They are made for various pressures, and num- bered accordingly. 413. What is a good rule to follow in selecting a spring? Ans. Select one numbered one-half as high as the boiler pressure, which will give a diagram about two inches high. 414. What data should be noted upon the diagrams when they are taken? Ans. Boiler pressure; time when taken, and which end of cylinder, head, or crank. 415. What pressure must always be deducted from the mean forward pressure (M. F. P.) in calculations for power ? Ans. The back pressure. 416. What bad effects follow unequal cut off? Indicator 63 Ans. The engine will not develop the power that it is capable of uneven strains will be set up. 417. What is a convenient size for a diagram? Ans. I 1 /? or 2 inches high, and 2 or 2 1 /*? inches long. 418. What precaution regarding the pipe connections of the indicator should always be observed before taking diagrams ? Ans. They should be thoroughly blown out, and cleaned of all dirt. 419. How is the ratio of expansion found? Ans. Divide absolute initial pressure by absolute ter- minal pressure. 420. Name a very important factor in the calculation of steam consumption of an engine. Ans. The clearance space. 421. What is one of the first requisites in power calcu- lations ? Ans. To ascertain the M. E. P. 422. How is this done? , : Ans. In several ways, for instance by means of ordinates, or it may be obtained by the use of the Planimeter. Lubrication 423. What is one of the most important problems con- nected with engine operation? Ans. The proper lubrication of the bearings. 424. What is friction? Ans. The resistance caused by the motion of a body in contact with another body that does not partake of its motion. 425. What is the first law of friction? Ans. Friction varies in proportion to the pressure on the surfaces in contact. 426. Define the second law of friction. Ans. Friction is independent of the areas of surface in contact. 427. What is the third law of friction? Ans. Friction increases with the roughness of the sur- faces, and decreases as the -surf aces become smoother. 428. What is the fourth law of friction? Ans. Friction is greatest at the beginning of motion. 429. Give the fifth law of friction? Ans. Friction is greater between soft bodies than it is between hard bodies. 430. When, and by whom were these laws first formu- lated? Ans. In 1831-33 by Gen. Arthur Morin, a French en- gineer. 431. What is the tendency of friction with machinery in operation? 65 66 Steam Engineering Ans. It tends to cause the parts to adhere to each other. 432. How may this friction be largely obviated ? Ans. By proper lubrication of the rubbing surfaces. 433. Does friction serve any good purpose ? Ans. Yes, for instance the friction of the belt in con- tact with the rim of the pulley, also the friction of the driving wheels of a locomotive. 434. How many kinds of friction are there in connec- tion with machinery in operation ? Ans. Two, viz., the friction of solids, and the friction of liquids. 435. What is meant by the term co-efficient of friction? Ans. The ratio of the power required to move a body, and the pressure on that body. 436. What should be the object sought in the design of engine bearings? Ans. To obtain as large a rubbing surface as possible. 437. Mention some of the qualities that a good lubri- cating oil should possess. Ans. It should have a good "body" must not dry or "gum ;" must not be easily thinned by heat, or thickened by cold. Must be free from all gritty substances. 438. What is the proper kind of oil to use on a bearing that has started to heat? Ans. Cylinder oil, owing to its high fire test. 439. Is graphite, or plumbago a good lubricant? Ans. It is in many cases. 440. What is the essential function of graphite? Ans. It is an auxiliary, or accessory lubricant. 441. Mention some of the points that govern interior lubrication of engine parts. Lubrication 67 Ans. The conditions of the surfaces ; the steam pressure ; the amount of moisture in the steam ; piston speed ; weight, and fit of moving parts, etc. 4:4:2. What properties should a good cylinder oil possess ? Ans. It must be of high flash test; must have good viscosity, or body when in contact with hot surfaces. 443. Upon what does the successful lubrication of an engine largely depend? Ans. Upon the character of the lubricating appliances used. 444. What system of lubrication for cylinders, and valves is most largely used? Ans. The hydrostatic, or sight-feed type of lubricator. 445. What other system has come into extensive use in late years? Ans. The force feed, or mechanically operated oil pump. The Steam Turbine 446. Explain the chief points of difference between the action of the reciprocating steam engine, and the steam turbine. Ans. The piston of the reciprocating engine is driven back and forth by the static expansive force of the steam; while in the steam turbine, not only is this static expansive force made to do work, but the velocity of the steam in ex- panding from a high, to a low pressure is also utilized in turning the rotor of the turbine. 447. What other important factors enter into the opera- tion of a steam turbine? Ans. The principles of reaction and impulse. 448. Name several of the more important advantages that the turbine has over the reciprocating engine. Ans. First, highly superheated steam of a high initial pressure may be used in the turbine. Second, a larger proportion of the heat in the steam may be converted into work with the turbine. Third, there is much less friction with the turbine. 449. What is the most economical method of disposing of the exhaust steam from a turbine? Ans. By allowing it to pass into a condenser. 450. Will the turbine expand the steam to as low a pressure as the reciprocating engine will? Ans. Yes, and even lower. 69 70 Steam Engineering 451. What type of condensing apparatus is necessary with the steam turbine. Ans. The same kind that is used on reciprocating en- gines. 452. How low will a well regulated turbine allow the steam to expand ? Ans. To within one inch of the vacuum existing in the condenser. 453. What is the theoretical velocity of steam under 100 Ibs. pressure if allowed to discharge into a vacuum of 28 inches? Ans. 3860 feet per second. 454. How many ft. Ibs. of energy would one cubic ft. of steam thus exert? Ans. 59,900 ft. Ibs. 455. What is the ratio of bucket speed to jet speed for impulse wheels. Ans. Bucket speed equals one-half of jet speed. 456. What should be the ratio between bucket speed and jet speed, for reaction wheels. Ans. 1 to 1. That is, the two speeds should be equal. 457. What should be the form or curvature of the blades, or buckets? Ans. They should be of such form as will permit expan- sion of the steam with the least amount of friction, or eddy currents. 458. How are the stuffing boxes of steam turbines usu- ally kept cooled? Ans. By means of water applied in various ways. 459. How is the speed of steam turbines usually regu- lated? Steam Turbines 71 Ans. By simple throttling. 460. What are the ideal conditions under which a tur- bine should work? Ans. A full initial pressure, and all cross sections of steam passages to be suitable to the power required. 461. Of what type is the Westinghouse-Parsons turbine ? Ans. It is both an impulse and reaction turbine. 462. How are the clearances between the blades pre- served in this turbine? Ans. By means of balancing pistons on the shaft. 463. What is the usual velocity of the steam in the Westinghouse-Parsons turbine ? Ans. 600 ft. per second. 464. How does the efficiency of steam turbines compare with that of reciprocating engines? Ans. It is generally higher. 465. How is the heat energy in the steam imparted to the wheels of the Curtis turbine? Ans. Both by impulse and reaction. 466. Describe the method of admission in the Curtis turbine. Ans. The steam is admitted through" expanding nozzles in which nearly all of the expansive force of the steam is transformed into the force of velocity. The steam is caused to pass through one, two, or more stages of moving ele- ments, each stage having its own set of expanding nozzles, each succeeding set of nozzles being greater in number and of larger area than the preceding set. 467. What is the ratio of expansion in these nozzles? 72 Steam Engineering Ans. The ratio of expansion within these nozzles de- pends upon the number of stages, as, for instance, in a two- stage machine, the steam enters the initial set of nozzles at boiler pressure, say 180 Ibs. It leaves these nozzles and enters the first set of moving blades at a pressure of about 15 Ibs. 468. In a four-stage machine, with 180 Ibs initial pres- sure, what would be the pressures at the different stages ? Ans. First stage, 50 Ibs.; second stage, 5 Ibs.; third stage, partial vacuum, and fourth stage, condenser vacuum. 469. How are the revolving parts of the Curtis turbine supported ? Ans. Upon a vertical shaft, which in turn is supported by, and runs upon a step bearing at the bottom. 470. How is this step bearing lubricated? Ans. Oil is forced under pressure by a steam or elec- trically driven pump, the oil passing up from beneath. 471. How is the speed of the Curtis turbine regulated ? Ans. By varying the number of nozzles in flow. 472. How are the clearances adjusted in the Curtis turbine ? Ans. By means of the large step screw at the bottom. 473. How is the shaft packed to prevent steam leakage? Ans. With carbon blocks made into rings fitting the shaft. 474. What type of turbine is the De Laval? Ans. It is purely an impulse wheel. 475. What is the speed of the wheel? Ans. From 10,000 to 30,000 revolutions per minute. 476. How is the heat energy in the steam utilized in the De Laval turbine? Ans. In the production of velocity. Steam Turbines 73 477. What is the velocity of the steam as it issues from the expanding nozzles and impinges against the buckets ? Ans. About 4,000 ft. per second. 478. What is the usual peripheral speed of the wheel? Ans. 1,200 to 1,300 feet per second. 479. Of what type is the Allis-Chalmers steam turbine ? Ans. It is essentially of the Parsons type. 480. How are the clearances between the revolving and stationary blades preserved? Ans. By a thrust bearing. 481. What kind of bearings has the Allis-Chalmers turbine ? Ans. Self-adjusting ball and socket bearings. 482. What is the first move in preparing to start a steam turbine? Ans. Open the throttle slightly and allow a small vol- ume of steam to flow through in order to warm the tur- bine. 483. What should be done next? Ans. Start the auxiliary oil pump. 484. What are the principal precautions to be observed when starting a steam turbine? Ans. To see that the turbine is properly warmed, also to be certain that the oil is circulating freely through the bearings. 485. What type of turbine is the Hamilton-Holzwarth steam turbine? Ans. It is an impulse turbine. 486. Describe in brief its construction? Ans. There are no balancing pistons in this machine, the axial thrust of the shaft being taken up by a thrust ball-bearing. The interior of the cylinder is divided into 74 Steam Engineering a series of stages by stationary discs which are set in grooves in the cylinder and are bored in the center to allow the shaft, or rather the hubs of the running wheels that are keyed to the shaft, to revolve in this bore. 487. In what respect does this turbine resemble a com- pound reciprocating engine? A ns. The steam is first admitted to the high pressure casing, and from there it passes into the low pressure cas- ing, which is larger in diameter. 488. Describe the action of the steam upon the blades? Ans. The expansion of the steam takes place entirely within the stationary blades, which also change the direc- tion of its flow, distributing it to the running vanes. 489. What additional function do the stationary vanes perform ? Ans. They take the back pressure, thus acting as balanc- ing pistons. 490. What type of governor has this turbine? Ans. The spring and weight type. 491. How are the bearings lubricated? Ans. The oil is forced into the bearings under pressure by an oil pump. 492. Of what type is the Rateau steam turbine? Ans. It is an impulse turbine having wheels of thin plates, slightly conical. 493. How is the rotor balanced? Ans. The same pressure exists on both sides of each rotating wheel. 494. Does the steam act by velocity or pressure? Ans. By velocity in this case. 495. What are the essential features of the Reidler- Stumpf steam turbine? Steam Turbines 75 A ns. The peculiar form of bucket, and the parallel return of the steam. 496. What is meant by parallel return of the steam? Ans. The steam enters the buckets through nozzles, and is deflected through an angle of 180 degrees, thus leav- ing the rotating buckets in a direction parallel to that of its entrance. 497. Describe the action of the steam within the Reid- ler-Stumpf turbine. Ans. Instead of escaping after having once passed through the buckets, it is caught by the guides or stationary buckets and returned to the wheel; this process being re- peated again, and again until all of the energy in the steam has been made to do work. 498. How many types of this turbine are there? Ans. Two, viz.: The single flow, and the double flow. 499. How is the highest efficiency obtained in the oper- ation of the steam turbine ? Ans. By allowing the exhaust steam to pass into a condenser. 500. Is it possible to maintain as high vacuum with the turbine as with a reciprocating engine? Ans. Experience demonstrates that a higher vacuum may be maintained in the condenser of a turbine than is possible with reciprocating engines. 501. What kind of condensing apparatus may be used with steam turbines? Ans. Any one of the modern improved types. 502. What is required in order to maintain a high vacuum in any type of condenser? Ans. That all entrained air be excluded. 503. How may this be accomplished? 76 Steam Engineering Ans. By means of a dry air pump. 504. In what manner does the dry air pump differ from an ordinary air pump? Ans. The dry air pump handles no water, and the clear- ances are made as small as possible. 505. To what extent does the steam turbine expand its working steam? Ans. To within one inch of the vacuum existing within the condenser. 506. Is the steam turbine adapted to the use of super- heated steam? Ans. It is. Highly superheated steam may be used, and a high vacuum maintained. 507. Is the water of condensation from turbines desir- able for boiler feed ? Ans. It is, for the reason that it contains no lubricating oil, and is a comparatively pure water. The Gas Engine 508. In what respect does the gas engine differ from the steam engine structurally? Ans. It is a much more ponderous machine than a steam engine of equal output, and usually requires a much heavier crank shaft. 509. Why should this be? Ans. Because the ordinary four-stroke-cycle, gas engine has only one working stroke in four, and requires four limes as much cylinder area for a given amount of work, as would a steam engine for the same work. 510. Define the difference between a single acting four stroke cycle and a double acting or two stroke cycle gas engine in their operation. Ans. In the four stroke engine two revolutions of the crank are required for one cycle. In the cfouble acting or two stroke, the cycle is completed in one revolution of the crank. 511. Why are gas engine crank shafts made larger in proportion than those of steam engines? Ans. In order that they may withstand the increased torsional strains. 512. What causes the pressure behind the piston of the gas engine? Ans. The combustion within the cylinder of a charge of gas and air properly mixed to form an explosive, and admitted at the proper moment. 513. When is this proper moment? 77 78 Steam Engineering Ans. When the piston is at the end of its instroke ready to start outward. 514. Define the stages of a four cycle engine. Ans. First, induction; during an out stroke of the piston, air and gas are drawn into the cylinder in the proper proportions. Second, compression; on the return stroke the piston compresses this combustible mixture into the clearance space. Third, explosion ; ignition of the compressed charge causes a rapid rise of pressure and sub- sequent expansion of products. Fourth, expulsion; the expanded gases are expelled by the returning piston. 515. Define the stages of a two cycle gas engine. Ans. First, compression of the charge. Second, igni- tion, explosion, and expansion, and at the end of the stroke the expanded products are expelled, and the cylinder filled by another charge of air and gas under pressure. 516. How many compression chambers are needed for the two cycle gas engine? Ans. Two; for the reason that this type of gas engine requires two cylinders, either side by side, or tandem, and the charge of gas and air is being received in one cylinder, while the previous charge in the other cylinder is being compressed preparatory for explosion. 517. How is the usefulness of the gas engine as a prime mover made apparent? Ans. By the fact that a suitable power gas may now be produced from almost any kind of commercial fuel. 518. What are the relative volumes of gas and air re- quired for combustion in a gas engine? Ans. This depends upon the kind of gas. Natural gas requires 10 to 12 cu. ft. of air per cubic feet of gas, while producer gas requires equal volumes of gas and air. The Gas Engine 79 519. Is blast furnace gas suitable for fuel gas? Ans. Yes, because it is slow burning, thus permitting high compression. 520. To what pressures may it be compressed ? Ans. 160 to 200 Ibs. per sq. in. 521. Is the^e as much heat in a given volume of blast furnace gas as in the same volume of natural gas ? Ans. No, there is about 40 per cent less. 522. How is the charge of gas and air drawn into the cylinder of a gas engine? Ans. By the suction of the piston. 523. What precaution should be observed regarding the admission of the air and gas? Ans. The air should be pure and free from dust, and the gas should not contain tarry matters if it can be avoided. 524. How are the induction valves usually set? Ans. So that the first portion of the charge is air only, then air and gas, and finally air with a small quantity of gas. 525. How is the air valve controlling the entry of the entire charge adjusted? Ans. It is set to open well in advance of the inner dead center of the engine, and is kept from closing until after the outer dead center. 526. Why is this valve so set? Ans. In order that the full effect of the momentum imparted to entering gases at the highest rate of piston speed may be utilized. 527. Upon what does the allowable compression pres- sure depend? 80 Steam Engineering Ans. Upon the relative proportions of hydro-carbon gases, and hydrogen contained in the mixture. 528. What per cent of hydrogen is considered within the limits of safety? Ans. Not over 7 per cent. 529. What are the usual compression pressures carried with blast furnace gas? Ans. 200 Ibs. per sq. in. 530. What pressure may be safely carried when pro- ducer gas is used? Ans. From 150 to 200 Ibs. per sq. in. 531. If illuminating gas is used, what is the maximum safe pressure? Ans. 120 Ibs. per sq. in. 532. How is the cylinder cooled and cleaned? Ans. By the injection of water or cold air through the clearance spaces, and valve ports during the charging stroke, or by pressure during compression. 533. What other methods are available for cooling the cylinder and piston rod ? Ans. By means of a water jacket that surrounds the cylinder. The piston rod may be hollow and water cir- culated through it. 534. How is the charge of gas and air ignited? Ans. Formerly by hot tubes of porcelain or hecnum, which are still used to some extent, but at the present day electrical ignition devices are used principally. 535. What kind of electrical devices are used for this purpose ? Ans. Primary batteries, storage batteries, and magneto machines, or the current may be taken from the lighting, or power circuit. The Gas Engine 8l 536. How many types of primary batteries are in com- mon use? Ans. Two Dry and wet batteries. 537. What are the elements commonly used in the wet battery? Ans. Carbon and zinc immersed in a jar or cell con- taining a solution of sal ammoniac, or sulphate of copper. 538. Describe the copper oxide battery. Ans. It consists of a plate of copper oxide, and a zinc plate, both being immersed in a solution of caustic potash. 539. What is the usual voltage of these cells? Ans. From 1 to 2 volts per cell. 540. Describe in brief the construction of the storage cell? Ans. It consists of gridded frames of lead, part of which are filled with red lead for the positive plates, and those for the negative plates are filled with litharge, all being im- mersed in a solution of 6 parts of water to 1 part of sul- phuric acid. 541. How is a dry battery made? Ans. A round zinc case forms one of the elements, and a piece of carbon in the center of the case forms the other element. 542. Are there any other ingredients? Ans. Yes A mixture of powdered manganese, carbon, and flour is packed around the carbon, while the rest of the can is filled with a plaster mixture of oxide of zinc and flour, and the whole is soaked in a solution of sal ammo- niac and zinc chloride. 543. In what manner does the electric current ignite the charge- of gas in the cylinder? 82 Steam Engineering Ans. By means of the jump spark caused by alternately making and breaking the circuit. 544. What is one of the most important features con- nected with ignition? Ans. To see that ignition occurs at the proper moment. 545. At what point in the stroke of the piston should ignition occur? Ans. This depends upon the quality of the gas used. With the maximum allowable percentage of hydrogen, igni- tion should not occur until after the piston has passed the inner dead center. Otherwise the result will be violent shocks, and strains upon the working parts. 546. Do high initial explosions create the most powerful efforts behind the piston? Ans. They do not. 547. What are the usual terminal pressures for gas engines ? Ans. 25 to 30 Ibs. above atmospheric pressure. 548. How is the horse power of a gas engine calculated ? Ans. Usually from the same formula used in connec- tion with the steam engine, and the computation is based upon the mean effective pressure developed at each ex- plosion. 549. What percentage of the total calorific value of the coal is usually converted into useful work with the steam engine? Ans. From 5 to 10 per cent. 550. What percentage of the energy contained in the fuel is it possible to utilize with a modern gas-driven unit? Ans. From 16 to 20 per cent. 551. How many type of apparatus are in use for the production of gag for power? TKe Gas Engine 83 Ans. Three: the suction producer, the steam pressure producer, and the induced down draft producer. 552. What kind of fuel must be used in the suction, and steam pressure producers? Ans. Coke, or anthracite coal. 553. What kind of fuel is the induced down draft pro- ducer adapted for? Ans. Bituminous coal. 554. How may gas engine efficiency be expressed? Ans. In terms of heat value. 555. Is there any difference of importance between a gas engine, and a gasoline or oil engine ? Ans. None of any importance. A gas engine may be easily converted into a gasoline engine, or vice versa. 556. Wherein lies the principal difference between the two kinds of engines? Ans. In the gas engine proper the gas is supplied to the cylinder by the producer. In the gasoline engine the gas is generated within the cylinder, from a charge of gasoline. 557. How may the action of the gas within the cylinder of a gas engine be ascertained ? Ans. By means of diagrams taken with an indicator. 558. Is there any difference between a steam engine in- dicator, and an indicator adapted for gas engines ? Ans. None in principle. The gas engine indicator is made somewhat stronger owing to the high pressures used. UNIVERSITY OF Air Compressors 559. What is one of the results of compressing air? Ans. The development of heat. 560. What amount of work is lost by the development and dissipation of this heat? Ans. The work represented by the mechanical equiva- lent of the heat developed. 561. Mention another cause of more or less lost work in air compression? Ans. Friction of the air in the pipes through which it is conveyed. 562. By what two methods is air compression generally accomplished ? Ans. Isothermal, by which the heat of compression is carried away as fast as developed ; and adi^abatic, by which no heat is removed from the air. 563. Which of the two is the ideal method of com- pression ? Ans. The isothermal. 564. Is it possible of attainment? Ans. Not entirely. 565. What may be said of the adiabatic method? Ans. It is one which should be avoided as much as possible. 566. What are the actual results secured in the best compressors ? Ans. They are intermediate between the two meth- ods just mentioned, but nearer to the second method. 85 86 Steam Engineering 567. Upon what does the efficiency of an air compres- sor depend principally? Ans. Upon the effectiveness of the cooling devices. 568. How many practical methods of removing the heat of compression are there? Ans. Two jacket cooling, and intercooling. 569. Is jacket cooling of the compressor-cylinder ef- fective ? Ans. Not entirely, except with single-stage compres- sion. 570. What is an intercooler? Ans. It is a cooling device interposed between the cylinders of a compound or multi-stage machine, through which the air passes on its way from one cylinder to the next one. 571. Describe the process of compression by the multi- stage method? Ans. A multi-stage compressor has two or more cylin- ders, the intake or low pressure cylinder being the lar- gest in diameter, and in which the air is first compressed to a low pressure, and then passed on into the next cylin- der which is of smaller diameter, where the air is com- pressed to a still higher pressure, and so on in increasing ratio. 572. How should the cylinder ratios be proportioned? Ans. So that the M. E. P. and the final temperature are equal in all the cylinders. 573. Describe the construction of an intercooler? Ans. It usually consists of a nest of tubes through which cold water circulates, and between which the stream of air passes. Air Compressors 87 574. Which method, single-stage, or multi-stage, ap- proaches nearest to the theoretical ideal? Ans. The multi-stage, with intercoolers. 575. Mention another point in favor of multi-stage compression ? Ans. It permits a higher piston speed, thus econo- mizing in steam. 576. What is one of the greatest difficulties encoun- tered in air power transmission? Ans. Freezing of the moisture in, the air, either in the pipe line, or at the exhaust ports of the air motors. 577. How may this condition be avoided to a large extent? Ans. By the proper cooling of the air during compres- sion, which will precipitate the moisture, which may then be withdrawn by drain pipes. 578. What would be the resultant temperature of air compressed from atmospheric pressure, and 60 Fahr., to a final pressure of 100 Ibs., provided there was no cooling device ? Ans. 484 Fahr. 579. What effect would this have upon the cylinder lubricant ? Ans. It would be burned, and be useless. 580. What would be the temperature of the same volume of air if compressed in the first, or intake cylinder of a multi-stage machine to a pressure of 25 Ibs. ? Ans. 233 Fahr. 581. If passed through an intercooler on its way to cylinder No. 2, what would its temperature be? Ans. It would be brought back to its original tem- perature of 60 Fahr. and enter the second cylinder under a pressure of 25 Ibs. 88 Steam Engineering 582. What would the temperature of the same air be if compressed in cylinder No. 2 from 25 Ibs. to 100 Ibs. pressure ? Ans. It would be but little in excess of that attained in the first cylinder, viz., 233 Fahr. 583. Why would it not attain the temperature stated in the answer to question 578, viz., 484 Fahr.? Ans. Because the heat of compression is a function of the number of compressions, and practically independent of the initial pressure. 584. Why is air compression at high altitudes more ex- pensive than at sea level? Ans. Because the capacity of the compressor decreases in a greater ratio than does the power necessary to com- press. 585. At an elevation of 10,000 ft. above sea level, what is the increase in expense ? Ans. Over 20 per cent. 586. What should be the first care in the installation of an air compressor? Ans. To provide a suitable foundation. 587. What precautions should be observed in the pip- ing? Ans. First, there should be as few L's as possible, and second, all pipes should be thoroughly cleaned before start- ing the compressor; third, allowance should be made for expansion. 588. What is the function of the unloader on the In- gersoll-Eand air compressor? Ans. To take the load off the air piston when the pres- sure reaches the desired point. 589. What is the function of the regulator? Air Compressors 89 Ans. To regulate the supply of steam to the steam end of the compressor. 590. What type of air inlet valves is this compressor equipped with? Ans. Piston inlet valves. 591. Describe the action of these valves? Ans. The air enters and passes through the piston, thus tending to keep it cooled. 592. What is the function of the Mason pump gov- ernor, with which some air compressors are equipped? Ans. To maintain a constant speed regardless of the load. 593. What kind of inlet valves is the Dallett air com- pressor fitted with? Ans. Either mechanically operated valves, or auto- matic poppet valves, as desired. 594. With what type of valves are the Allis-Chalmers air compressors usually equipped? Ans. Rotary valves for the inlet, and single-beat poppet valves for the discharge. 595. How are the inlet valves operated? Ans. By an eccentric on the main shaft, and a wrist plate. 596. What other type of valve-gear are some of these compressors equipped with? Ans. Both inlet, and discharge valves are actuated by independent eccentrics on the main shaft. Refrigeration 597. Of what does the process of refrigeration consist? Ans. In the abstraction of heat from a substance. 598. Describe a freezing mixture that will give a tem- perature of 67 degrees below zero. Ans. A mixture of one pound of calcium chloride, and 0.7 Ibs. of snow. 599. Upon what are the theory, and practice of mechan- ical refrigeration based? Ans. Upon the two first laws of thermo-dynamics. 600. What is the first of these laws? Ans. Mechanical energy and heat are mutually con- vertible. 601. Define the second law. Ans. An external agent is necessary tp complete or bring about this transformation. 602. Is heat generated by compression, or by any other means ? Ans. It is not generated but developed, because there is a fixed amount of heat in the universe which can neither be increased nor diminished. 603. "What is the result of compressing one pound of air at 70 degrees temperature and at atmospheric pressure, to one half its original volume ? Ans. An increase in its static pressure, also an increase in its temperature. 604. In order that the higher pressure may be main- tained, as the temperature is reduced, what is necessary? 91 92 Steam Engineering Ans. A small additional quantity of air will have to be forced into the compressor cylinder. 605. If the pound of compressed air be allowed to ex- pand in a cylinder what will be the result ? Ans. A portion of the heat developed by compression will be given up. 606. What can be said of the mechanical work done by this air in its expansion? Ans. In amount it is exactly the same as that done upon it during its compression. 607. How is the temperature of a body or substance reduced ? Ans. By transferring more or less of the heat con- tained in the body to some other substance or body. 608. What work is demanded of a refrigerating ma- chine? Ans. To extract heat from a body, and by the expendi- ture of mechanical energy to sufficiently raise the temper- ature of this heat to admit of its being carried away by a suitable external agent, usually water. 609. How may a refrigerating machine be defined, and what is its main function? Ans. As a heat pump, its main function being the abstraction of heat from the body to be cooled, and trans- ferring that heat to a cooling agent. 610. How may the various devices for refrigeration and ice making be classified? Ans. Under five principal heads. 611. Explain the action of apparatus belonging to class one. Ans. Heat is abstracted from the body to be cooled, by the dissolution or liquefaction of a solid, as for instance the cooling of water with ice. Refrigeration 93 612. Describe the vacuum system? Ans. The abstraction of heat is effected by the evapora- tion of a portion of the liquid to be cooled, the process being assisted by an air pump. 613. How is refrigeration effected in machines belong- ing to the third class? Ans. By the evaporation of a separate refrigerating agent, which is subsequently restored to its original physi- cal condition by mechanical compression and cooling. 614. Describe the fourth or absorption system. Ans. Heat is abstracted by the evaporation of a sepa- rate refrigerating agent, under the direct action of heat, which agent again enters in solution with a liquid. 615. Describe the action of machines belonging to the fifth class, known as cold air machines ? Ans. Air, or other gas is first compressed, then cooled, and afterwards permitted to expand while doing work. 616. What two systems have come into general use in the United States? Ans. The ammonia compression system, and the am- monia absorption system. 617. What are the three distinct stages in the com- pression system? Ans. Compression, condensation, and expansion. 618. What is the refrigerating agent or medium used in the compression system? Ans. Anhydrous ammonia. 619. Of what does ammonia consist, and what is its chemical formula? Ans. One part of nitrogen, and three parts of hydro- gen. Its chemical formula is NH 3 . 620. Under what two conditions may gaseous ammonia be liquefied? 94 Steam Engineering Ans. At a pressure of 128 Ibs. per sq. in., and a tem- perature of 70 Fahr., or a pressure of 150 Ibs, and a tem- perature of 77 Fahr. It may also be liquefied by cold if its temperature be reduced to 85.5 Fahr. below zero. 621. To what pressure is gaseous ammonia usually compressed ? Ans. From 125 to 175 Ibs. per sq. in. 622. Of what does a compression plant consist? Ans. Of a high pressure system made up of a condens- ing coil surrounded by cooling water, and a low pressure system consisting of an evaporating coil surrounde4 by brine, or open to the room to be cooled. 623. What takes place during compression? Ans. The latent heat of the vapor is converted into active, or sensible heat. 624. How is the vapor condensed, or liquefied? Ans. It is forced into and through the condenser coils which are submerged in a body of cold water, or over which cold water is flowing, and the sensible heat developed dur- ing compression is thus transferred to the cooling water. 625. How are the refrigerating qualities of the am- monia in its liquefied state utilized? Ans. It is allowed to pass in small quantities from the condenser into pipe coils placed in the rooms to be cooled, when it again expands into a vapor, and takes up an amount of heat exactly equivalent to that given up during condensation. 626. After being expanded into vapor, what becomes of it? Ans. It is drawn back into the compressor, again com- pressed, condensed, and expanded, the cycle of operations being repeated indefinitely. Refrigeration 95 627. How many, and what are the systems of refrigera- tion by compression? Ans. Two the wet system, and the dry. 628. Describe the theory of the wet system. Ans. The ammonia vapor is cooled by the injection into the compressor C3 r lmder of a small quantity of liquid ammonia at the beginning of each stroke, and it is carried from the cooling room back to the compressor in a sat- urated state. It is thus kept in contact with a small por- tion of its originating fluid, and is kept comparatively cool. 629. Upon what does the pressure of steam in a boiler depend ? Ans. Upon its temperature, which is always the same as that of the water in the boiler. 630. What are the relations of temperature and pres- sure in the case of steam while in contact with the originat- ing water? Ans. They are interdependent. 631. What is the result if the steam is superheated? Ans. It may still be of the same pressure, but its tem- perature will be higher. 632. What results from the compression of a dry gas without cooling? Ans Its temperature may be much higher than that corresponding to its pressure. 633. What does the Adiabatic curve as traced by the indicator represent? Ans. The compression, or expansion of a gas without loss or gain of heat. 634. Describe in brief the construction of the cylinder heads, and valves in the Linde ice machine. 96 Steam Engineering Ans. The piston and cylinder heads are spherical, and of the same radius, and the valve discs conform to this radius. 635. What is the clearance between piston and cylin- der head ? Ans One thirty-second of an inch. 636. How is the piston lubricated? Ans. In a large measure by the moisture in the am- monia vapor. 637. In the De La Vergne refrigerating machine how is the heated gas cooled? Ans. By passing it through coils of pipe surrounded by running water. 638. How many valves has the Triumph ice machine? Ans. Five, three suction valves, and two discharge valves. 639. What advantage is said to be gained by the use of the third suction valve? Ans. That it tends to increase the economy of the ma- chine. 640. Describe the construction of a double pipe am- monia condenser. Ans. It consists of two series of coils, one within the other. 641. How many methods are there of utilizing refrig- eration ? Ans. Two; the brine system, and the direct expansion system. 642. Describe in brief the brine system. Ans. The coils of pipe in which the ammonia is ex- panded are submerged in a solution of salt, or calcium chloride. This brine after being reduced to a low tempera- Refrigeration 97 ture is pumped through coils of pipe in the rooms to be cooled. 643. Describe the direct expansion system. Ans. The expansion coils are placed in the rooms to be cooled, and the cooling is effected directly by the expansion of the ammonia. 644. Which one of the two systems is the most efficient? Ans. The direct expansion system. 645. Mention a few of the advantages that this system has over the brine system. Ans. First All intermediate agencies are dispensed with. Second The whole plant is much simpler. Third A larger expansion surface. 646. By what two systems is ice made or manufactured? Ans. The can system and the plate system. 647. Mention other refrigerating agents besides am- monia that may be used in the compression system ? Ans. Ether, methyl-chloride, sulphurous acid, and car- bonic acid. 648. How is refrigeration effected in the absorption system ? Ans. By the continuous distillation of ammoniacal liquor. 649. What advantage appertains to the absorption, system ? Ans. The bulk of the heat required for the work is applied direct without being transformed into mechanical power. 650. What pressure is usually maintained in the gen- erator ? Ans. 150 Ibs. per sq. in. 651. Mention the more important features of the ab- sorption machine? 98 Steam Engineering Ans. The expansion valve, the absorber, and the strength of the liquor. 652. Upon what does the efficiency of the machine mostly depend? Ans. Upon the condition of the absorber. If it is cool and free from air, or poor gas, better results will be realized. 653. What should be done if one side of the absorber should get warmer than the other ? Ans. The spray valve should be turned down slightly, say one-eighth of a turn. 654. Mention one of the troubles in the operation of this system. Ans. A filling up of the coils with scale and dirt. 655. What is the remedy in such cases? Ans. Stop the machine once a week, drain the coils, and blow them out with compressed air. 656. How is anhydrous ammonia formed? Ans. By condensing ammonia gas to a liquid, and applying pressure. 657. Under atmospheric pressure, what is the boiling point of anhydrous ammonia? Ans. 28.5 degrees delow zero Fahr. 658. What is the specific gravity of liquid ammonia compared with water? Ans. At 32 Fahr. it is about % that of water, or 0.6364. 659. What is its latent heat of evaporation ? Ans. At 32 degrees temperature it is 560 thermal units. 660. If evaporated at 32 Fahr. and atmospheric pres- Bure, how much space will one pound occupy? Ans. Twenty-one cubic feet. Elevators Electric and Hydraulic 661. What are the essential parts of the Otis traction elevator ? Ans. A traction motor driving sheave, and a pair of electrically released brake shoes. 662. What type of electric motor is used in the Otis traction elevator? Ans. A slow speed shunt-wound motor. 663. What is the principal function of the armature shaft besides carrying the armature? Ans. To support the load. 664. How, then, is the drum, or sheave driven? Ans. By means of projecting arms from the armature, that engage with similar arms projecting from the d.rum. 665. Describe the system of safety devices with which this elevator is equipped ? Ans. There are two groups of switches located, respec- tively at top and bottom of the shaft, each switch in series being opened one after the other by the car as it passes. This retards the speed and finally brings the car to stop, applying the brake, independent of the operator in car. 666. Are there any other safeties besides this ? Ans. Yes speed governors, wedge clamps for gripping the guides, and potential switches. 667. Describe in general terms the construction of the Otis geared traction elevator? Ans. A multi-grooved driving sheave around which th'e cable works. The sheave is mounted upon a shaft driven 99 100 Steam Engineering by geared wheels actuated by a right and left hand worm cut on the armature shaft. 668. What advantage is gained by the use of the double screw, or worm ? Ans. The elimination of all end thrust. 669. With what kind of brake is this machine equipped? Ans. A mechanically applied, and electrically released brake. 670. What type of motor is used? Ans. Compound-wound speed 800 R. P. M. 671. When is the series field of this motor used? Ans. Only at starting. 673. Why? Ans. To obtain a highly saturated field in the shortest possible time. 673. How is a gradual slowing down of speed of car obtained with this elevator? Ans. By throwing a low resistance field across the ar- mature, thus providing a dynamic brake action. 674. What kind of current is used for operating elec- tric elevators? Ans. Either alternating, or direct current. 675. How is the transmission of current to the motor of an electric elevator controlled? Ans. By means of an electric magnet controller op- erated through the switch in the car. 676. How may considerable power be wasted in the operation of electric elevators? Ans. By careless handling making unnecessary stops and starts, or too sudden stops or starts. 677. Briefly, of what does the mechanism of a hydraulic elevator consist? Elevators Electric and Hydraulic 101 Ans. A cylinder and piston with one or more rods con- nected to a crosshead which carries the sheaves over which run the lifting cables from which the car is suspended. 678. What moves the piston? Ans. Water under pressure admitted by means of suit- able valves causes the piston to move from one end of the cylinder to the other, and back again. 679. How is this motion transmitted to the elevator car? Ans. By means of the sheaves mounted on the cross- head which carry the lifting cables. 680. In what position is the cylinder placed ? Ans. Either vertical alongside the hatchway, or hori- zontal in the basement of the building. 681. How are the valves of a hydraulic elevator op- erated ? Ans. In some cases by a hand rope passing through the car and over small sheaves at the top and bottom of the hatchway, and connected with the main valve in the basement. By pulling this rope down the valve is opened, and the car will ascend, while pulling the rope up will cause the car to descend. 682. What safety devices are attached to this type of elevator ? Ans. Two balls are attached to the hand rope, one near the bottom, and the other near the top. These balls come in contact with the top, or bottom of the car, according as it is going up or coming down, and being carried along they, of course move the cable, thus actuating the valve, bringing the car to a stop. 683. Is this device safe, and automatic? Ans. It is. 102 Steam Engineering 684. Mention another safety device connected with hydraulic elevators. Ans. Safety clamps under the control of a speed limit centrifugal governor which causes the clamps to grip the guides and thus hold the car. 685. How is this safety governor operated? Ans. By means of a small cable connected with the car and moving with it, which passes over the sheave pulley of the governor. 686. Why are some elevator pistons fitted with two pis- ton rods? Ans. To prevent the piston, and crosshead from turn- ing or twisting, and also to strengthen the construction. 687. What other methods are used for manipulating the water valve, besides the one already described? Ans. Running ropes, and standing ropes, either of which may be operated by means of a lever, or wheel in the car. 688. Do these devices directly operate the main valve? Ans. No. They operate a small valve called the pilot valve. 689. What is the function of the pilot valve? Ans. When opened it admits the pressure water to a small cylinder with piston connected to the main valve stem. This actuates the main valve, which in turn, by its movement, closes the pilot valve. 690. Upon what does the amount of opening given the pilot valve, and consequently the main valve depend? Ans. Upon the distance the lever in the car is moved from central position. 691. What is meant by central position of lever? Elevators Electric and Hydraulic 103 Ans. That position in which there is no flow of water either into or out of the cylinder, and the car is moving only by its momentum. 692. What is the result of moving the lever too quickly to central position when the car is moving at a high rate of speed? Ans. The motion of the car will be arrested with a sudden jerk. 693. How many kinds of horizontal hydraulic elevators are in use ? Ans. Two. One is the pushing, and the other the pulling type. 694. Describe the action of the pushing type? Ans. The car being at the bottom, the pressure water is admitted behind the piston which then moves, pushing the crosshead and cable sheave and lifting the car. 695. Describe the action of the pulling type? Ans. It is the opposite of that just described. 696. Is there much difference in the valve mechanism of the horizontal, and vertical types of hydraulic elevators ? Ans. Very little except a few minor details. 697. What is meant by a double-deck machine? Ans. Where the floor space is restricted two, and some- times three or four machines are mounted one above the other. 698. What water pressure is usually carried in operat- ing the types of hydraulic elevators that have hitherto been described? Ans. Pressures not exceeding 200 Ibs., the average being 150 Ibs. per square inch. 699. Are any higher pressures than this being used for operating hydraulic elevators? Ans. Yes. Pressures of 700 to 800 Ibs. and higher. 104: Steam Engineering 700. Why are such high pressures used? Ans. Owing to increased height of buildings, and the demand for high car speed. 701. What advantage, other than high speed, is gained by the use of high pressure elevators? Ans. A reduction in the size of the valve mechanism, piston areas and piping. 702. Mention another advantage in connection with the high pressure system? Ans. A reduction in the loss by friction of the water passing through the pipes, owing to reduced areas. 703. What is the percentage of loss due to this cause? Ans. In low pressure machines from 10 to 30 per cent, and in high pressure machines from 5 to 6 per cent. 704. Describe in general terms the construction of the cylinder and piston of a high pressure machine. Ans. The cylinder area is reduced to about one-eighth that of the low pressure type, and the piston is a solid plunger. 705. How is the pressure maintained? Ans. The pump forces water into the lower end of the accumulator, an air-tight tank, which is also weighted. From the accumulator a pipe runs to the main valve. 706. Describe in general terms the construction and operation of the direct-acting plunger elevator. Ans. A cylinder is set vertically in the ground under the center of the car, and the length of it is slightly greater than the travel of the car. In this cylinder is a plunger of the same length, which carries the car. Water under pressure is forced into the cylinder and thus lifts the car, and allowed to run out at the top when the car descends. The cylinder is about two inches larger in dia- meter than the plunger, and is always full of water. Elevators Electric and Hydraulic 105 707. What is the usual diameter of the plunger? Ans. 6!/2 to 7 inches. 708. How is it constructed? Ans. Of lengths of highly polished steel pipe, joined together with an internal sleeve, and having its lower end closed. 709. What pressure is ordinarily used on this type of elevator ? Ans. 150 to 200 Ibs. per square inch. 710. How is the top of the cylinder arranged? Ans. With a packing gland through which the plunger moves up and down. 711. What types of elevators are in general use for passenger service? Ans. Electric and hydraulic. 712. How is the capacity of a pump usually expressed? Ans. In gallons of water per minute raised to a given height. 713. What is meant by the head under which a pump works ? Ans. The vertical distance between the surface of the water in the suction reservoir, and that in the discharge reservoir. 106 Steam Engineering FIG. 514 Electricity for Engineers 714. What is electricity? Ans. Electricity is an invisible agent. Its exact na- ture is not very well known, although the laws govern- ing its action, the methods of controlling it, and the ef- fects produced by it are becoming well known. 715. Is it correct to use the term quantity with refer- ence to electricity? Ans. It is. We may use terms to designate definite quantities of electricity, passing through a conductor, in the same way that we speak of gallons of water flowing through a pipe. 716. Is it proper to assume that there are large quanti- ties of electricity stored for future use, in a manner similar to water? Ans. It is not, except in a limited sense, as in storage batteries. 718. Define the doctrine of the conservation of energy. Ans. The total quantity of energy in the universe is unalterable. When energy is expended, or disappears in one form, it must reappear in another form. 719. In accordance with this doctrine, what would be the proper term to apply to electricity with reference to the physical requirements of man? Ans. It is a useful agent for the rapid transmission of stored up energy in fuel, water falls, etc. 720. What is the practical unit of quantity used in speaking of electricity? 107 108 Steam Engineering Ans. The coulomb. It is that quantity of electricity that would pass in one second through a circuit carrying a current of one ampere. 721. What is an ampere? Ans. It is the unit of volume, or rate of flow. A cur- rent of one ampere will flow through a circuit whose re- sistance equals one ohm, when the electro-motive force, or pressure behind it equals one volt. 722. What is a volt? Ans. The volt is the unit of electro-motive force, and represents a pressure that will cause the flow of one am- pere through a circuit in which the resistance equals one ohm. 723. What is an ohm? Ans. The ohm is the practical unit of electrical resist- ance. It is that amount of resistance that would limit the flow of electricity under an electromotive force of one volt, to a current of one ampere, or to a discharge of one coulomb per second. It equals the resistance of a column of mercury one sq. millimetre in area of cross sec- tion, and 104.9 centimetres in length. 724. What is the unit of work? Ans. The foot pound. 725. What is the unit of power, or rate of doing work? Ans. The foot pound, per second. 726. How is the amount of work that electricity is ca- pable of doing, measured ? Ans. By the volt-coulomb, or Joule. The amount of electrical work per second is equal to the volt ampere, or watt. 727. What amount of power developed is represented by the watt? What is Electricity 109 Ans. 44.25 foot-lbs. of work per minute, or 0.7375 foot- Ibs. per second. 728. What is a magnet ? Ans. A mineral consisting of a combination of iron and oxygen. 729. What is the chemical formula of a magnet? Ans. Fe 3 4 . 730. What is a permanent magnet? Ans. A piece of steel that has been charged with mag- netism, and retains it. 731. What is meant by the poles of a magnet? Ans. All magnets tend to point north and south, the same end always pointing in the same direction ; hence the end pointing north is called the north pole, and the end pointing south is termed the south pole. 732. What peculiar characteristic attaches to the poles of magnets ? Ans. The north poles of two magnets tend to repel each other, and the same is true of the south poles. But the north pole of one magnet attracts the south pole of an- other, like repels like, and unlike attracts unlike. 733. What is an electro magnet? Ans. A bar of iron surrounded by a coil of wire through which an electric current is passing. 734. What are lines of force? Ans. They are certain imaginary lines passing through the steel of the magnet from its south pole to its north pole, and issuing from the latter they curve around through space and return to the south pole. 735. What is the magnetic circuit ? Ans. It is the path of these lines of force, around and through the magnet. It resembles a closed curve, either a circle, or an ellipse. 110 Steam Engineering 736. Explain the difference between the magnetic cir- cuit and the electric circuit. Ans. The magnetic circuit, or field of force, that sur- rounds a magnet is maintained without the expenditure of energy, while on the other hand an electric current passing upon its circuit develops energy, and energy must be ex- pended to maintain it. 737. Are there any other points of difference between the two circuits. Ans. Yes, the electric current passes through a con- ductor in intensity proportional to the electro-motive force urging it, while the magnetic circuit passes through air, or a vacuum in proportion to the magneto-motive force urging it. 738. What is meant by the term potential as applied in electric practice? Ans. Voltage or pressure. 739. What is the law of induction ? Ans. When a conductor is moved in a magnetic field of force so as to cut the lines of force, there is an electro- motive force impressed on the conductor in a direction at right angles to the direction of motion, and at right an- gles to the direction of the lines of force. 740. What is a dynamo? Ans. A machine for transforming mechanical energy into electrical energy. 741. How is the field of force maintained in a dynamo? Ans. By means of electro-magnets. 742. Does not this require the expenditure of energy? Ans. Yes ; a certain amount of energy is indirectly ex- pended. 743. How are dynamos classified? The Dynamo 111 Ans. Into two grand divisions, viz., direct current dy- namos and alternating current dynamos. 744. What is direct electrical current? Ans. A current of unchanging direction. 745. What is an alternating current ? Ans. A current that reverses its direction of flow, pe- riodically, from 20 times and upward per second. 746. Name the principal constituent parts of a dy- namo. Ans. The armature, the field, the collecting rings, or commutator, and the brushes. 747. How is electro motive force or current induced in a dynamo? Ans. By rapidly changing field and armature relations by means of mechanical energy. 748. How is the output of a dynamo stated? Ans. In Kilowatts equal to 1,000 X volts X amperes. 749. How is the output of a motor statod ? Ans. In horse power, equal to Watts intake -r- 746 X ef- ficiency expressed decimally. (Not as a percentage.) 750. What is the voltage of a dynamo? of motor? Ans. It is the pressure that the generator or alternator delivers at its own terminals. The voltage of a motor is the voltage which should be applied to its terminals in order to develop full horse power. 751. What is full load current of dynamo? of motor? Ans. Full load current of a dynamo is that current which may be drawn steady for 24 hours without causing any part of the machine to exceed a safe temperature, i. e., 150 Fahr. This applies to factory motors. 752. What is meant by the rating of a dynamo ? Of a motor ? 112 Steam Engineering Ans. The product of full load current multiplied by the voltage expressed in Kilowatts is rating of a dynamo. The actual mechanical horse power developed at the pinion of the motor as tested in shop. 753. What is the armature core? Ans. The sheet iron body which carries the armature winding, and conducts the flux from pole piece to pole piece. 754. What is the armature spider ? Ans. The casting consisting of hub and arms which supports armature core. 755. What are binding wires? Ans. They are narrow bands of phosphor bronze wire placed around the armature every three or four inches to help bind the winding to the core. They rest on strips of mica, and are sweated with solder all around. 756. What are commutator segments? Ans. The commutator segments or bars are the copper pieces of which the commutator is built. 757. What are commutator leads? Ans. They are the ends of the armature winding ex- tending from the core to the lug of the commutator bar. 758. What are pole pieces? Ans. The end of the magnet core nearest the armature. Usually larger than the core. 759. What are magnet cores? Ans. The iron inside the field coil. 760. What is the yoke? Ans. The part of magnetic circuit connecting the mag- net cores. 761. What is the pitch of an armature winding? Ans. It is the number of teeth between the two sides of a formed coil plus one tooth. The Commutator 113 Example : The two sides of a coil are in slots number 3 and 17, then pitch is 14. 762. Is there insulation between winding and core? Ans. Yes. Mica or fuller board; there is also the tape on coil. 763. What insulation is there between conductors of winding ? Ans. The double cotton covering of each wire makes four thicknesses between conductors. 764. What is the air gap? Ans. It is the air space between armature and pole pieces. In dynamos it is made as small as possible for ef- ficiency. In motors it is not made too small because this tends to make the machine spark due to the weak field. In D. C. series motors it is from % to % of an inch, in A. C. series motor it is smaller, say 1/10 to % inch. The larger the air gap of a motor the more the bearings may wear before there is danger of the armature rubbing against the lower pole pieces. 765. What are field spools? Ans. The brass shells on which the field coils are wound. 766. What is the commutator? Ans. It is a series of copper bars placed parallel to the shaft, insulated from each other and from the frame of the machine. Each is connected to the winding and cur- rent flows from the winding through them to the brushes. It at the same time reverses the connections between the brushes and the winding at the proper times so that the brush always collects current. 767. What is a collector or slip ring? 114 Steam Engineering Ans. A collector consists of two or more rings of copper placed around the shaft and insulated from it, and each other. Each is connected to a part of the winding. The brushes rest on the rings. They are used to collect current from a revolving arma- ture style of alternator, to feed current into armatures of rotary converters, or the revolving fields of alternators. The collector has no corrective influence and passes on the A. C. or D. C. current exactly as it receives it. Single phase machines have two rings; two, three, and six phase machines have three rings. 768. Is there a difference between no load and full load voltage of dynamos? Ans. Yes. A shunt dynamo gives highest voltage at no load and lowest at overloads ; the series dynamo gives lowest at no load and highest at full load. The compound dy- namo is a combination of series and shunt, and gives same voltage at all loads. An alternator acts like a shunt dynamo. 769. What is a field rheostat? Ans. It is a resistance in the field circuit which can be varied to change the current, and hence the field strength. This alters the voltage of the dynamo. 770. What are commutated fields? Ans. In some motors the field coils are arranged in sec- tions so that they may be arranged in parallel, or series, or in combinations. All coils in parallel give the greatest current and hence slowest speed of motor; all coils in series give the weakest field and the fastest speed. 771. What relation has field strength to the speed of motor ? Armature Winding 115 Ans. The weaker the field the faster the speed, for the motor must revolve fast to generate its proper counter E. M. F. 772. What relation has armature strength to the speed of motor ? Ans. The greater the armature current the higher the speed. 773. What effect on the power of motor does field, and armature strength have? Ans. The greater the field and armature current the greater the power. 774. What is a ring winding? Ans. One which passes over and under around the core, a space being left between the shaft and core to accommo- date the winding. 775. What is a drum winding? Ans. One where all winding is on the outer surface of the core. 776. Upon what does sparkless commutation of current depend ? Ans. (1) The more commutator bars the better, there being less voltage and therefore tendency to spark between bars. The average railway motor has from 100 to 125 bars on commutator. (2) The fewer the ampere turns on the armature in comparison to the ampere turns on the field the less spark- ing. (3) The more turns short-circuited by the brush when touching two or more bars at once, the greater the tendency to spark. 777. What is a shunt field? Ans. One whose coils are placed as a shunt across the brushes. It carries a small current. 116 Steam Engineering 778. What is a series field? Ans. One which carries the main, or nearly all the main current, and is placed in series with the armature. A small strip of resistance metal is used sometimes to di- vert a portion of the main current from the series field. 779. What are Foucault, or eddy currents? Ans. Local currents set up within the armature, and acting as a hindrance to the generation of useful current. 780. How may the electro-motive force he increased ? Ans. By increasing the speed, or by adding more turns or loops of wire to the armature winding. 781. What is meant by self excitation of a dynamo? Ans. When the dynamo is standing still, the field mag- nets become weakly magnetic, but when the armature begins to revolve a few volts of electric current will be sent through the field coils, gradually increasing the magnetic strength until full voltage is reached. 782. What is a series dynamo ? Ans. One in which the same current that travels the main circuit also traverses the field. 783. Explain the action of the shunt dynamo. Ans. The field circuit is a shunt, and only a portion of the main current passes through it. 784. How are the fields of a compound dynamo ex- cited? Ans. The fields have two distinct windings ; one shunt, and the other series. 785. What advantage pertains to the compound wound dynamo ? Ans. It is practically self-regulating. 786. What is the difference between the dynamo and the electric motor? The Currents 117 Ans. Practically none in the principles governing the design of the machines. Any dynamo may be used as a motor, and vice versa. 787. State the difference in their functions. Ans. The dynamo converts mechanical energy into elec- trical energy, while the motor converts electrical energy into mechanical energy. 788. Upon what does the power to be obtained from a motor depend? Ans. Two things, viz., the current flowing in its arma- ture coils, and the strength of magnetism developed in its fields. 789. How is the speed of motors controlled? Ans. By a starting box or rheostat. 790. How may the direction of rotation of a motor be reversed?. Ans. By reversing the current through either the ar- mature or the fields. 791. Upon what principle does the alternating current motor act ? Ans. Upon the principle of induction, having for its main accessory the rotary field. 792. How is a rotary field produced? Ans. By the use of polyphase currents. 793. Explain the meaning of the term rotary field. Ans. In a rotary field the rotary action is purely elec- trical, the poles simply rotating around the circle. There is no rotation of the mechanism of the field. 794. What then is a revolving field? Ans. A field that revolves around an axis like a wheel. 795. What is the leading characteristic of the direct current ? 118 Steam Engineering Ans. It travels in the same direction of pressure. 796. What is the tendency of the current generated in all dynamos? Ans. It is alternating in voltage or pressure. 797. Explain the meaning of the term alternating as used in this connection. Ans. The current starts at a value of zero, rises to a maximum of polarity, descends to a value of zero again, and changing in direction of pressure, rises to a maximum of opposite polarity, from whence it drops to zero again. 798. How then is direct current produced from this al- ternating current? Ans. By means of the commutator and brushes on the direct current generator. 799. What is the leading characteristic of the alternat- ing current? Ans. Its voltage is continually changing at regular in- tervals from zero to maximum in the direction of opposite polarity. 800. How is this action best represented? Ans. By wave curves drawn above and below a horizon- tal line representing zero. 801. In what manner does the action of the alternating current affect the circuit through which it travels ? Ans. The whole circuit passes simultaneously through voltage values of the cycle represented by the wave curve. 802. What is meant by the frequency of an alternating current ? Ans. The number of waves or cycles per second. 803. What does a frequency of 60 mean? The Voltage 119 Ans. It means that the voltage values pass through a complete cycle in one sixtieth of a second, that is 60 cycles per second. 804. What is meant by alternations? Ans. The number of reversals per minute in the di- rection of pressure. 805. How many alternations would there be in a cur- rent having a frequency of 60 ? Ans. 7,200. 806. What is meant by a "period?" Ans. The time in seconds or fractions of a second re- quired to pass through a complete cycle. 807. What is meant by current wave? Ans. It means the actual values of the current as shown by the volt-meter and ammeter. 808. Do these equal the values of the theoretical wave curve ? Ans. They do not, reaching about 70 per cent. 809. Why is this? Ans. It is due to the influence of the iron magnetic circuit caused by the connections of induction motors, arc lamps, and other electrical apparatus. 810. What is meant by effective current? Ans. The voltage and volume as shown by the volt- meter and ammeter. 811. In what respect is the maximum voltage as shown by the calculated wave curve useful? Ans. It is useful in testing insulating materials. 812. What is meant by phase in electric practice? Ans. It denotes the relative position of a current wave. with respect to the wave of electro-motive force producing it. 120 Steam Engineering 813. When is a current in phase? Ans. When the two waves just mentioned start at zero and reach their maximum values at the same instant. 814. What is meant by lag? Ans. When the current wave lags behind the voltage wave. 815. What is meant by lead? Ans. When the current wave is ahead of, or leads the voltage wave. 816. What is the meaning of two and three phase cur- rents ? Ans. When the winding of the armature is such that two or three electro-motive forces in quadrature with each other are simultaneously produced by the generator the cur- rents thus produced may be distributed over four or six conductors, a pair for each current. 817. Is it necessary to have a pair of conductors for each current in two and three phase current work ? Ans. No. By means of the Y winding it is possible to distribute the current over three wires, each wire acting as a main, and return wire for one of the others. Armature Design and Construction 818. Can the properties of a dynamo be accurately cal- culated from any of the formulas given for that purpose? Ans. No. The accurate design of a new type of dynamo, and an armature as well, is as much a matter of experiment as it is of calculation. 819. Why is this? Ans. There are so many factors involved in the calcu- lation that cannot be accurately determined until a ma- chine of the exact dimensions of the one under considera- tion has been built. 820. What are the principal factors that are so trouble- some to determine? Ans. The permeability of the iron, the resistance of the magnetic circuit, the tendency to leakage of the lines of force, the exact proportion of the dead wire, the reaction of the armature, the losses due to Foucault currents. 821. Are not the causes of all these losses well under- stood ? Ans. They are, and it is easy enough to tell what must be done to lessen any or all of them. It is merely their exact value which is indeterminate until the machine in question is in operation. 822. What is the chief precaution which must be taken on this account. Ans. It is necessary to leave some part of the controlling influences so that they can be readily varied and thus adjust the machine so that it will be exactly right when it is finally finished. 823. How can this best be done? Ans. Since it is manifestly very troublesome to rewind 121 ' 122 Steam Engineering an armature, if perchance too great or too small a number of wires have been placed upon it, the proper factors to be arranged to be variable are : the speed, and the strength of the field. In some cases the speed, even, is not changeable, and the whole duty of compensating for misjudgment in the calculations falls upon variations of the field strength. 824. Can the whole regulation be accomplished in this way? Ans. It can, and in most cases this is the method relied upon. It is very easily accomplished by this method if we arrange to have the fields magnetized to only a low degree of saturation. By doing this, however, we are led to provide field magnets whose capacity is far in excess of what we believe to be necessary and, therefore, more expensive. So that again in the last consideration it behooves us to experi- ment before we definitely determine the exact proportion of our dynamo or motor. 825. Are there any formulae that can be used in deter- mining the exact proportions? Ans. There are, and they are given below. These will materially assist the student in forming an idea how the different parts can be adjusted to bring about the desired final result. For the following formulas we shall adopt the attached set of symbols: Let F=the total number of lines of force, or flux, V=the number of volts to be generated, S=the number of slots in the armature, R.P.S.=:the number of revolutions per second, W=the number of wires per slot. Then, to find the number of wires necessary per slot where the speed and flux are fixed: 10 8 XV "TP" ~ Formulae 123 To find the necessary speed where the number of wires, and the flux, are fixed: 10 8 XV R. p. S.r= FXSXW To find the necessary strength of field, where the wires and speed are fixed : F== 1Q8 x y SXR.P. s.xw To find the volts generated : FXSXWXR.P. s. V=- 10 8 826. Are these formulae used in actual practice to deter- mine the size of wire, speed, etc. ? A ns. These formulas are of value principally in check- ing up the actual calculations made. 827. How. is an armature actually designed? A ns. In actual practice whenever a new dynamo or motor is to be constructed it is, so to speak, built up around the armature. That is to say, the armature must first be designed, and the other parts made to fit around it. 828. What is the principal consideration to be taken into account? Ans. In order to deliver a certain current, the number of poles, etc., being fixed, which is with rare exceptions the case, we must use a certain size wire. 829. Is there no choice whatever in the size of wire for a given current? Ans. There is some choice. In most cases the heating of the wire on the armature determines the size of wire to be used; in other cases it is the drop in potential at the terminals of the armature that governs. 124 Steam Engineering 830. How does the size of wire affect the heating, and the loss of potential? ^4.715. Both of these losses, and the troubles occurring from them, are lessened by selecting wires of greater diameter. 831. How do you proceed to calculate the necessary size of wire? Ans. The number of wires, and the dimensions of the armature for any given purpose can be found by trial cal- culations only. By this we mean that, unless we are very lucky, we shall have to make a number of calculations, using, perhaps, different dimensions and wires before we get the result that suits us best. S32. Give an example. Ans. As an example let us take an armature 8 inches in diameter and 8 inches in length and see what it will do for us. Such an armature has a cross-section of 64 sq. inches and, assuming a flux of 30,000 lines of force per square inch, we have a total flux of 1,920,000 lines through the armature. We first find how often one wire must cut this number of lines of force to generate, say, 110 volts. To do this we first divide 110X100,000,000 (which is the total number of lines to be cut per second) by the total flux, 1,920,000, and obtain as the result 5728. Next, to get the necessary number of wires to be placed upon the armature, we must divide this quotient (5728) by the number of revolutions the armature makes per second. If our armature revolves at the rate of twenty revolutions per second (1,200 per minute) we shall need one-twentieth of 5,728 wires placed upon it. This amounts to 286. As our armature, 8 inches in diameter, has a circumference of 25.12 inches, this gives us a wire running about 11 per Wire Used 125 inch. If there is to be but one layer, this gives a number 12 wire. As the two sides of the armature are in parallel we have a capacity of 2 times 14.31 amperes according to Table 50. If we decide to use two layers, we can take a No. 6 wire, 5.5 per inch, and obtain a capacity of 56.55 amperes. It may be stated in explanation of the calcula- tions here made that each wire in the course of one revolu- tion of the armature cuts the total flux two times; but as the two halves of the armature are in parallel, each side must produce the full voltage by itself. 833. How much radiating surface is usually allowed per watt of energy used up ? Ans. That depends very much on the work for which the armature is intended. If it is for a railway motor, which is entirely enclosed, and almost constantly in use, it is much more than, for instance, an elevator in a private residence where there is but very little use, and only at long intervals, so that the armature has time to cool off between one run and another. Table 50 is based upon the require- ment that there shall be three square inches of radiating surface for each watt of energy expended in the coils. 834. What radiating surface is allowed for each watt expended in the case of an armature? Ans. This amount varies in different machines, being as low as 1 square inch per watt, and as high as three square inches per watt. About 1.75 square inches per watt ex- pended can be considered as a fair average for armatures and about 3 inches per watt expended for field coils. 835. How is the table referred to (Table 50) made up? Ans. This table is figured from the formula, 126 Steam Engineering R S being the radiating surface, and R the resistance of a unit of length of the wire under consideration. This form- ula gives the current allowed where the wire is wound in one layer. As we add more layers we must, with each suc- cessive layer, reduce the current, so that the square of the current multiplied by the resistance (which equals the watts) shall remain always the same, because increasing the depth of the winding does not affect the radiating sur- face of the coil. 836. The table gives the carrying capacity only to a depth of six layers ; how is the carryng capacity of a greater number of layers to be found? Ans. To do this we refer to Table 50 and select from the column headed P the number pertaining to the wire in question. This number represents the square of the cur- rent permissible with one layer of wire. Divide this num- ber by the number of layers it is intended to use, and extract the square root of the number so found. The result will be the carrying capacity of the wire in question, wound to a depth of that number of layers. As a general guide we may bear in mind that, as we multiply the number of layers by 4, 16, 64, 256, we, each time, decrease by one-half the carrying capacity of the wire. From this we can see that the capacity of the wires after a certain number of layers have been considered, decreases very slowly, though very fast with the first few layers. 837. Is there need of very great accuracy in these calculations ? Ans. Great accuracy is not necessary in these calcula- tions. We can always lengthen our armature a little by adding a few punchings, should the potential be insufficient, and we can always vary the speed and strength of field con- Tables B. & S. Gauge. Diameter bare. Resistance per foot 140 F. Diameter D. C. C 'tOtOD9COj&.CNpS;^pOpU>i MM MM tO tO CO M M M M U> IO O CO ^ * CT ^ 00 JO M OS OS CD W ^ tC> 1 ^ i ^ H^ H* tC t C fC -* M M M to tO 03 03 rf- O< O5 -1 00 O Jd 4- O> O CO 00 Number of wires per inch. 128 Steam Engineering jaSS 1 10^5^04 THrH stun) jo oo^ 958. What is the function of the wattmeter? Ans. To record the watt-hours of work. 959. What is a kilo watt (K. W.) ? Ans. 1,000 watts. 960. Expressed in horse-power, what is one K. W. equal 162 Steam Engineering Ans. 746 horse-power. 961. What is a field rheostat? Ans. An apparatus for controlling the current output. 962. What is the function of a transformer? Ans. To transform the current from a higher to a lower voltage, or from A. C. to D. C. 963. What is meant by synchronism of electric ma- chines ? Ans. When the maximum value of the E. M. F. in each machine occurs at exactly the same instant of time, the machines are in synchronism. 964. What is meant by the exciter panel of a switch- board ? Ans. It is the panel that is equipped with the necessary switches, etc., for connecting the small exciter dynamo with the other generators in the station. 965. What is a sub-station? Ans. It is the connecting link between the transmission line, and the trolley wire or third rail. 966. When A. C. is generated at the power station, and D. C. is used on the line, how is it accomplished ? Ans. The A. C. is changed to D. C. by rotary converters at the sub-station. 967. What is meant by frequency? Ans. The number of times the current reverses per sec- ond. 968. What is the usual frequency for railway motors? Ans. 25 is the standard. 969. What is a frequency changer? Ans. A machine which receives current at one frequency and delivers it at another frequency. 970. What apparatus is used in an A. C. to D. C. sub- station ? Switchboards 163 Ans. Step down transformers, rotary converters, and A. C. incoming and D. C. outgoing switchboards. 971. What is the proper procedure for placing rotary converters in service? Ans. After the machine .has been started from the A. C. ends, and builds up with the proper polarity, first close the equalizer switch (on machine) second, close circuit breaker on panel third, insert potential plug in receptacle and regulate voltage fourth, when the proper voltage is obtained, close positive switch (on panel). 972. What will be the result if the rotary builds up with polarity reversed? Ans. The voltmeter will swing back of zero. 973. How may the polarity be corrected ? Ans. By means of the four-pole, double-throw field break-up reversing switch mounted on the converter. 974. Describe an oil switch. Ans. It is a switch similar in its action to other switches, with the exception that its mechanism is im- mersed in a small tank of oil. 975. What advantage is gained thereby? Ans. Eeliability of action in opening or closing a cir- cuit. 976. Mention another advantage gained by the use of the oil switch and oil circuit breaker. Ans. It has made safely possible the transmission and use of high-tension currents of electricity. 977. What is a circuit breaker? Ans. It is a switch so designed as to be capable of fre- quently opening the circuit carrying its full current with- out any damage to itself. 978. What is a galvanometer? 164 Steam Engineering Ans. An instrument consisting of a coil of wire car- rying the current to be tested, and a magnet, the two be- ing arranged so that one can be deflected. 979. Describe the Thompson type of galvanometer. Ans. The coil of wire is stationary, and the light mag- netic needle is suspended by a silk thread. 980. What is a lightning discharge? Ans. An equalization of potential between the earth, and either clouds, or saturated atmosphere. 981. What path does the discharge generally follow ? . Ans. The path of least resistance. 982. What are the general requirements for protection of electric stations from lightning? Ans. The supplying of paths to ground for any charge which might accumulate on lines or machinery. 983. What is the general theory of the multi-gap light- ning arrester? Ans. When voltage is applied across a series of multi- gap cylinders, the voltage distribution is not uniform, but is governed by the capacity of the cylinders, both between themselves, and also to ground, which results in the con- centration of voltage across those gaps nearest the line. 984. What are the principal elements of a 600 volt D. C. aluminum lightning arrester? Ans. Two concentric aluminum plates immersed in an electrolyte contained in a glass jar, the outside plate of each cell being positive, and the inner one negative. 985. Describe the multigap lightning arrester for A. C. Ans. It consists of a series of spark gaps shunted by graded resistances, but without series resistance. 986. Describe briefly the aluminum lightning arrester. The Galvanometer 165 Ans. It consists of two aluminum plates on which has been formed a film of hydroxide of aluminum, immersed in a suitable electrolyte. 987. Describe the D'Arsonval galvanometer. Ans. In this type the small light coil of wire is sus- pended by a fine bronze wire between the poles of a station- ary magnet. 988. How are the readings taken from these instru- ments ? Ans. From a circular scale, over which the needle of the instrument swings. Definitions A. C. Alternating Current. Absorption. The act of one form of matter sucking, or draining in some other form of matter, as in the case of a sponge taking up water. Acceleration. The increase of motion. Accumulated Electricity. Electricity confined or stored, as in a condenser. Accumulator. Sometimes used to designate a condenser, a Ley den jar, or a storage battery. Active Coil. A coil or conductor conveying a current of electricity. Active Current. The active constituent of an alternating current, in contradistinction from the wattless compo- nent. Active Wire. The section of wire on the armature of a dynamo which goes through the field of force, in con- tradistinction from the remaining wire, which does not pass through the flux. Aerial Circuit. An elevated circuit. Air Blast. A blast of air acting upon the surface of a commutator to prevent damaging flashes. Also used to cool transformers in some cases. Air Gap. Any gap or aperture in a circuit which con- tains air only. Air Insulation. Insulation produced by the action of air. 167 168 Steam Engineering American Wire Gauge. The name by which the Brown & Sharpe wire gauge is known, in which the diameter of the largest wire, No. 0000, is 0.46 inches, and wire No. 36, 0.005 inches, and all other diameters progress in geomet- rical order. Ammeter. An abbreviation for ampere meter. Used for measuring current rate, or volume. Any calibrated gal- vanometer having its scale marked to read amperes is an ammeter. Ampere. The unit of electric current flow. An ampere is that volume of current which would pass through a cir- cuit that offered a resistance of one ohm under an electro- motive force of one volt. Ampere Hour. A unit of quantity equal to the amount of electricity transmitted by one ampere flowing during one hour. Ampere Turn. A unit of magneto-motive force equal to the force resulting from the passing of one ampere over a single turn of wire. Anode. The positive pole a battery. Arc. A segment of a circle. A voltaic arc. Armature Reaction. The reactive magnetic effect result- ing from the action of the current in the armature of a dynamo on the magnetic circuit of the machine. B B. S. G. British standard gauge. B. & S. W. G. Brown & Sharpe wire gauge. B. W. G. Birmingham wire gauge. Balanced Load. A load uniformly apportioned to two or more generators. Balanced Resistance. A resistance arranged in a bridge, and balanced by the residuary resistance in the bridge. Definitions 169 Bar Windings. Armature windings constructed of copper bars. Bipolar. Possessing two poles. Birmingham Wire Gauge. A wire gauge used in England. Booster. An auxiliary dynamo used to increase the volt- age of a feeder, or a set of feeders beyond the voltage of the rest of the system. Bridge, Electric. A contrivance used to measure unknown resistances by comparison with adjustable ones. Bunched Cable. A cable having more than one wire, or conductor. Bus-bars. Bars composed of heavy conducting metal, and connected directly with the poles of generators. C C. G. S. Centimetre, Gramme, second. C. P. Candle power. Calibrate. To ascertain the complete or relative values of the indications of electrical measuring instruments. Candle. The unit of photometric energy. Equals the light produced by a standard candle burning at the rate of two grains per minute. Cathode. Opposed to anode. Condenser. A device for augmenting the capacity of an insulated conductor by placing it in contiguity to another earth-connected conductor, but from which it is sep- arated by an intervening body which will permit electro- static induction to occur through it. Constant Current. A current, the strength of which does not vary. Continuous Current. A current flowing in the same di- rection only. Cycle of Alternations. Alternations of the current per second. 170 Steam Engineering Coulomb. The unit of electric quantity accepted for prac- tice. That quantity of electricity that would pass in one second through a circuit conveying one ampere. That quantity of electricity contained in a condenser of one Farad capacity when subjected to an E. M. F. of one volt. D. D. C. Direct current. D. P. S. Double pole switch. Differential "Winding. Double winding of magnet coils resulting in the opposition of the two poles to each other. Dynamic Electricity. Current electricity as distinguished from static electricity. Dyne. The C. G. S. unit of force. E E. H. P. Electrical horse-power. E. M. F. Electromotive force. Electrolysis. Chemical decomposition by the action of an electric current. F Farad. The practical unit of electrical capacity. That capacity of a conductor that is capable of holding one coulomb at one volt potential. Feeders. Wires furnishing the main conductors with cur- rents at different points, thus serving to equalize the po- tential under load. Five- wire System. A system wherein four series connected dynamos are connected to five conductors. Flux. Magnetic induction; the number of lines of force which pass through a magnetic circuit. Frequency. Number of cycles per unit of time by an al- ternating current. Definitions 171 G Gramme. A unit of weight equal to the weight of one cubic centimetre of pure water at its maximum density, at a temperature of 39.2 Fahr. in a vacuum. A weight equal to 15.44 grains troy. H H. P. Horse-power. Hard-drawn Copper Wire. Copper wire hardened without annealing, by being drawn several times. Henry. The practical unit of electro-magnetic, or mag- netic inductance. Horse-power, Electric. A rate of electrical work equal to 746 watts, or 746 volt-coulombs per second. Hysteresis. Slowness of magnetization in respect to mag- netizing force. I Induction. The influence exerted without contact, by a magnetic field, or a charged mass upon, neighboring bodies. Inverted Arc Lamp. An arc lamp wherein the positive carbon is below instead of above, as in the regular arc lamp. J Jump Spark. A disruptive spark excited between two con- ductors, in distinction from a spark excited by a rubbing contact. K K. W. Kilowatt. Kilowatt. One thousand watts. Kilowatt-Hour. Work equal to the expenditure of one K. W. in one hour. 172 Steam Engineering L Lag. Dropping behind. Lagging of Current. The retarding in phase of an al- ternating current behind the pressure which produces it. M Megohm. One million ohms. Metre. A measure of length equal to 39.368 inches. Micro-Fard. The millionth of a Farad. Mil. One thousandth of an inch. Multiphase. Containing more than one phase. Multiple Circuit. A circuit in which the positive poles of a number of separate sources, and receptive devices are connected to a single positive lead or conductor; their negative poles being connected to a single negative lead or conductor. Multiple Series. Series groups connected in multiple. Ohm. The practical unit of resistance. A resistance that would confine the electric flow under an electromotive force of one volt to a current of one ampere, or one cou- lomb per second. Ohm's Law. The basic law, expressing the relation be- tween current, E. M. F., and resistance in active cir- E cuits. Expressed algebraically 1= , in which I equals R current intensity, E equals E. M. F., and K equals resist- ance. Other forms of expressing ohms law are as follows : Bbs-H E=BL Definitions 173 Over Compounded. Compound winding of such a charac- ter on a dynamo that its voltage at its terminals is caused to increase under a greater load. P Parallel Circuit. A term signifying multiple circuit. Parallel Series. Signifies a multiple series connection. Periodicity of Alternation. The rate of succession of al- ternations per second, or per minute. The frequency. Polyphase Current. Currents that constantly differ from each other, due to their proportion of periods of alter- nation, and adapted to polyphase motors. Proposed Definition for 2,000 Candle Power. An arc whose maintenance will require 450 watts. E Rheostat. Will adjust the resistance without opening the circuit. S Standard Ohm. A piece of pure copper wire one circular mil in diameter, and one foot long at a certain tempera- ture. Static Electricity. Electricity generated by 'friction. V Volt. The practical unit of electromotive force. An E. M. F. that would cause a current of one ampere to flow through a resistance of one ohm. W Water Horse-Power. The power developed by 15 cubic feet of water falling through a distance of one foot per second. Watt. The practical unit of electric activity, rate of work, or energy. A watt equals 44.25 foot pounds of work done per minute, or 0.7375 foot-pounds of work done per sec- ond. Watt-Hour. Unit of electric work. One watt exerted or expended for one hour. INDEX A Absolute Pressure 57 Absolute Zero 40 Absorption System of Refrigeration 97-98 Acceleration of Gravity 25 Adiabatic Curve .58-59 Air Compressors 85-89 Air Compression at High Altitudes 88 Air Compression Methods of 85, 86, 87 Air Required for Combustion 33 Alternator 114 Alternating Current 111-118 Ammeter 161 Ampere 108-161 Angular Advance 52 Anhydrous Ammonia 93-94 Armature Construction 121-148 Armature Troubles 148-152 Armature Winding 133-148 Atlas Water Tube Boiler . 12-13 B Babcock and Wilcox Boiler 8-9 Back Pressure 57 Bigelow Hornsby Boiler 10-11 Blow Off Pipe and Cock 22-27 Boiler Material 15 Boiler Setting and Equipment 19-25 Boyles Law 58 Brick for Boiler Setting . . 19 Brine System of Refrigeration 96-97 Brushes How to Set 151-152 Buck Stays 20 Bursting PressureRule for 18-37 i ii Index c Cahall Water Tube Boiler 7-8 Calculating Pump Capacity 24-25 Calorific Valve of Fuel 40 Calorimeter 44 Care and Operation of Boilers 31-38 Causes of Poor Combustion 38 Chimneys 29 Circuit Breaker 163 Classes of Mechanical Stokers 28 Cleaning Fires 31-32 Coal Composition of 39 Combustion Chamber 6, 7, 20 Combustion Heat 39-42 Compound Dynamo 116 Compression 52-54 Compound Engines 47, 49-50 Condensers 48, 75-76 Condensing Engine 47 Condenser Pressure 57 Conservation of energy 107 Coulomb 108-161 Co 2 Meaning of 39 Curtis Steam Turbine 71-72 Current Phase 120 Cut-off 53-54 D Dead Center 54 Direct Current 111-117 Dished Heads 17 De Laval Steam Turbine 72-73 Definitions Electric 167-173 Definitions Steam .57-59 De Lavergne Ice Machine 96 Domes and Mud-Drums 22 Draft Gauge 44 Drum Winding 115 Dry Air Pump 76 Duplex Water Tube Boiler 13-14 liidex iii Duties of an Engineer 31-32 Dynamics 59 Dynamo-Principle of 110-111. Dynamo Construction 112-114 Dynamotor 154 E Eccentric 52-53 Economizers 40 Efficient Joint 16 Electricity for Engineers 107-165 Electric Circuit 110 Electric Motor 116-117 Elevators Electric and Hydraulic 99-105 Erie City Water Tube Boiler 14 Equivalent 46 Evaporation Tests 43-46 Exhaust Injector 28 Expansion Curve 59 F Factor of Safety 18 Failure of Joints 16-17 Feed Pipes , 23 Feed Pumps 22-24 Feed Water Heaters 22, 27-29 Field Rheostat 114 Flue Gas Analysis 45 Foaming 34 Force 59 Former Coils 143 Friction Laws of 65-66 Frequency Electric 162 Fusible Plugs 21 G Galvanometer 164 Gas Engines 77-83 Gas Engine Indicator 83 Gas Engine Igniter 82 iv Index Gas Producers 83 Gauge Pressure 57 Governor , 55 Grate Surface 20 Grounded Circuit 150 Gusset Stays 17 H Hamilton-Holzwarth Steam Turbine 73-74 Heat 40 Heat Unit 41 Heine Water Tube Boiler 8 Horizontal Tubular Boiler 5 Horse Power 58 Hydraulic Elevator 100-105 I Imperfect Combustion 33 Indicator 61-63 Indicated Horse Power 58 Induction Laws of ,110 Ingersoll-Rand Air Compressor 88-89 Initial Pressure 57 Injector 23-24 Isothermal Curve 59 J Joule 108 K Kilo-Watt , Ill, 161 L Lap 53 Latent Heat 41 Lead 52-55 Lightning Arresters 164-165 Linde Ice Machine , 95 Low Water What to do in Case of 34 Lubrication . ,., 65-67 Index T M Magnet 109 Magnetic Circuit 110 Marzolf Water Tube Boiler 13 Maxim Water Tube Boiler 9-10 Mean Effective Pressure 58 Mechanical Draft Systems of 28-29 Mechanical Equivalent of Heat 41 Mechanical Stokers 28-29 Momentum 59 Motion First Law of 59 Motor Armatures , 146-148 O Ohm 108-161 Ohm's Law 161 Oil Switches 163 Open Circuit 151 Otis Geared Traction Elevator 99-101 Otis Traction Elevator 99 P Piston Displacement 58 Piston Speed v 58 Pitch of Boiler Rivets ! ..15-16 Pop Valve 21 Potential 110 Power 59 Principles of Boiler Construction 14 R Radius of Eccentricity 52 Ratio of Expansion 57 Rateau Steam Turbine 74 Reidler-Stumpf Steam Turbine 74-75 Refrigeration 91-98 Ring Winding 1 115 Rotary Converters 154-162 Rules for Firing . . . , 31-32 vi Index S Safety Valves 33 Series Dynamo 116 Short Circuit How to Locate 150-151 Shunt Dynamo 115 Simple Engine 47 Specific Heat 41 Steam 41-42 Steam Engines 47-70 Steam Gauge 21 Steam Headers 24 Steam Turbines 69-76 Switch Boards 159-164 Synchronizer 158 T Tensile Strength 14-15 Terminal Pressure 57 Theoretical Duty of Steam 59 Thermodynamics First Law of 59 Thermodynamics Second Law of 91 Through Stay Rods 17 Total Heat of Evaporation 46 Transformers 153-154 Triumph Ice Machine 96 Types of Boilers 5 Types of Valves 51 U Unit of Work 108 Unit of Power 108 V Vacuum 58 Valve Travel 52 Valves and Valve Setting 51-50 Valves for Boiler Connections 24 Volt 108, 161 Index vii W Washing Out Boiler 35-36 Water Composition of 41 Water Column 20-21, 36 Water Tube Boiler 5-6 Watt 108-109 Watt Meter 161 Westinghouse-Parsons Steam Turbine 71 Wickes Water Tube Boiler 11-12 Work , 59 The Calculation of Horse Power Made Easy : : : By L. ELUOTT BROOKES Author of "Gas and Oil Engine Hand-Book," "The Automobile Hand-Book," Etc. Size, 5x7%. 80 Pages, Illustrated. Cloth, 75 Cents THIS work deals in a practical and non- technical manner with the calculation of the power of Steam Engines, *Explo- sive and Electric Motors. Particular attention has been given to the full explanation of the elementary principles upon which the calculations are based. It has been the endeavor to present in as simple a manner as is possible, a number of useful rules and formulas that may be of great value to ENGINEERS, MACHINISTS and DESIGNERS in calculating horse power. Rules for plotting steam engine diagrams by arithmetical, geometrical and graphical methods are given and fully explained, also the method used in plotting the diagram of an explosive motor. This work covers many points regarding the calculation of horse power and useful information not hitherto published in a single volume, and includes Calculated, Brake and Indicated horse power, Point of cut-off and average steam pressure, Horse Power of Explosive Motors, Degree of Compression and Combustion Chamber Dimensions, Indicator Diagrams of Steam Engines and Explosive Motors, also tables of Average Steam Pressure, Areas of Circles, Squares of Diameters of Circles, Natural Logarithms of Num- bers, Thermo-dynamic Properties of Gasoline and Air, Common Logarithms of Numbers, and Mensuration of Surface and Volume. The term " Explosive Motor " includes Gas, Gasoline and Oil Engines. SENT POSTPAID TO ANY ADDRESS IN THE WORLD UPON RECEIPT OF PRICE FREDERICK J. DRAKE & CO. PUBLISHERS PUBLISHERS. CHICAGO, ILL. ELEMENTARY ELECTRICITY UP TO DATE By SIDNEY AYLMER-SMALL, M. A. I. E. E. r] i [IS book opens up the way for anyone who desires an accurate and complete knowledge of elec- tricity as a useful agent, in the hands of man, for the transmission of me- chanical energy, and the creation of light. In addition to opening up the way as referred to above, the book also serves as a guide and instructor to the seeker after knowledge along these lines. Beginning in the form of a simple catechism on the primary aspects of the subject it conducts the student by easy stages through the various as- pects of static electricity, the different types of apparatus for producing it, all of which are plainly described and illustrated and their action made plain and easy of comprehension. Quite a large, space is devoted to this important topic, although no more than is actually necessary, as the subjects of condensers and simple electrical machines are also thoroughly handled, and the principles governing their action clearly explained and illustrated. The subject of atmospheric electricity is next dealt with, and lightning arresters treated upon, especially in their relation to electric power stations.lsub-stations and line wires. The wonderful and mysterious subject of magnetism is next treated upon at length and clearly explained the explanations being accompanied by illustrations. Primary batteries of all types, storage batteries and the effects of elec- trolysis each and all receive a large share of attention. Electric circuits and the laws governing the flow of current, including Ohm's law, are all clearly explained. The student has now arrived at the point where electrical work, power and efficiency is the topic, and where the genera- tion and transmission of electrical currents of high potential and large volume are explained. Sold by booksellers generally or sent postpaid to any address upon receipt of price. 12 mo. Cloth, 500 Pages, Fully Illustrated : Price, $1.00 FREDERICK J. DRAKE & CO. PUBLISHERS : : : : CHICAGO, ILLINOIS Practical Armature and Magnet Winding By HENRY C. HORSTMANN and VICTOR H. TOUSLEY W 'HILE the subject of armature wind- ing has, in the past, been more or less completely covered, most of these works have been either too technical in their composition or have required a fair degree of knowledge of the subject before they could be clearly understood. There has been a need of a book cover- ing this matter which, while giving all that is necessary for an intelligent under- standing, would, at the same time, present the matter in such a simple form that it could be readily grasped by those who had not had the benefit of a previous education along this line. This book treats in a practical and con- cise manner this very important subject. All practical armature windings are fully explained with special atten- tion paid to details. All questions which are apt to arise in the minds of the students have been completely answered. Numerous illustrations have been supplied, and these, taken in con- junction with the text, afford a ready means for either the study of the armature or for a book of reference. It has been the aim of the authors to supply all the necessary informa- tion required by the subject and, at the same time, to give this informa- tion in as condensed and brief a form as is consistent with a clear understanding. Various useful tables have been especially prepared for this work and these will not only reduce to a minimum the number of calculations re- quired, but lessen the possibility of errors. A chapter on the calculation of armatures gives complete information in detail for the design of an armature. Sold by booksellers generally or sent postpaid to any address npon receipt of price. 16mo., Pocket Size, Full Persian Morocco Leather, Round Corners, Red Edges - - ... - $1.50 FREDERICK J. DRAKE & CO. PUBLISHERS .... CHICAGO, ILLINOIS OPERATORS' WIRELESS TELEGRAPH 1 AND TELEPHONE HAND-BOOK By VICTOR H. LAUGHTER I TP-TO-DATE and most com- V plete treatise on the subject yet published. Gives the historical work of early investi- gators on up to the present day. Describes in detail the construc- tion of an experimental wireless set. How to wind spark coil and dimensions of all size coils. The tuning of a wireless station is fully explained with points on the construction of the various instruments. A special chapter on the study of wireless telegraphy is given and the rules of the Naval sta- tions with all codes, abbrevia- tions, etc., and other matter in- teresting to one who takes up this study. The most difficult points have been explained in non- technical language and can be understood by the layman. Wireless telephony is given several chapters and all the systems in use are shown with photographs and drawings. By some practical work and a close study of this treatise one can soon master all the details of wireless telegraphy. Sold by booksellers generally or sent postpaid to any address upon receipt of price. 12mo., Cloth, 210 Pages, Fully Illustrated, and with Six additional Full-Page Halftone Illustrations Showing the In- stallation of "Wireless" on the U. S. War Ships and Ocean Liners -..--. $1.00 FREDERICK J. DRAKE & CO. PUBLISHERS . - . - CHICAGO, ILLINOIS Twentieth Century Machine Shop Practice By L. ELLIOTT BROOKES The best and latest and most practical work published on mod- ern machine shop practice. This book is intended for the practical instruction of Machinists, Engin- eers and others who are interested in the use and operation of the machinery and machine tools in a modern machine shop. The first portion of the book is devoted to practical examples in Arithmetic, Decimal Fractions, Roots of Num- bers, Algebraic Signs and Symbols, Reciprocals and Logarithms of Numbers, Practical Geometry and and Mensuration. Also Applied Mechanics which includes: The lever, The wheel and pinion, The pulley, The inclined planes, The wedge The, screw and safety valve Specific gravity and the velocity of falling bodies Friction. Belt Pulleys and Gear wheels. Properties of steam, The Indi- cator, Horsepower and Electricity. Th* latter part of the book gives full and complete information upon the following subjects: Measuring devices, Machinists' tools. Shop tools, Machine tools, Boring machines, Boring mills, Drill presses, Gear Cutting machines, Grinding Machines, Lathes and Mill- ing machines. Also auxiliary machine tools, Portable tools, Miscella- neous tools, Plain and Spiral Indexing machines, Notes on Steel. Gas furnaces. Shop talks. Shop kinks, Medical Aid and over Fifty tables. The book is profusely illustrated and shows views of the latest machinery and the most up-to-date and improved belt and motor- driven machine tools, with full information as to their use and opera- tion. It has been the object of the author to present the subject matter in this work in as simple and not technical manner as is possible. 12mo, cloth, 636 pages, 456 fine illustrations, price, $2.00 Sold by Bookseller* generally, or sent postpaid to any address upon receipt of Price by the Publishers FREDERICK J. DRAKE & CO. PUBLISHERS CHICAGO, U. S. A. DYNAMO TENDING for ENGINEERS Or, ELECTRICITY FOR STEAM ENGINEERS By HENRY C. HORSTMANN and VICTOR H. TOUSLEY, Authors of "Modern Wiring Diagrams and Descriptions for Electrical Workers." This excellent treatise is written by engineers for engineers, and is a clear and comprehensive treatise on the prin- ciples, construction and operation of Dynamos, Motors, Lamps, Storage Bat- teries, Indicators and Measuring Instru- ments, as well as full explanations of the principles governing the generation of alternating currents and a descrip- tion of alternating current Instruments and machinery. There are perhaps but few engineers who have not in the course of their labors come In contact with the electrical apparatus such as pertains to light and power distribution and generation, it the present rate of increase in the use of Electricity it is but a question of time when every steam installation will have in eonnecton with it an electrical generator, even in such buildings where light and power are supplied by some central station. It is essential that the man in charge of Engines, Boilers, Elevators, etc., be familiar with electrical matters, and ft cannot well be other than an advantage to him and his employers. It is with a view to assisting engineers and others to obtain such knowledge as will enable them to intelligently manage such electrical apparatus as will ordinarily come under their control that this book has been written. The authors have had the co-operation of the best authorities, each in his chosen field, and the information given is just such as a steam engineer should know. To further this information, and to more carefully explain the text, nearly 100 illustrations are used, which, with perhaps a very few excep- tions, have been especially made for this book. There are many tables covering all sorts of electrical matters, so that immediate reference can be made without resorting to figuring. It covers the subject thoroughly, but so simply that any one can understand it fully. Any one making a pretense to electrical engineering needs this book. Nothing keeps a man down like the lack of training; nothing lifts him up as quickly or as surely as a thorough, practical knowledge of the work he has to do. This book was written for the man without an opportunity. No matter what he is, or what work he has to do, it gives him just such information and training as are required to attain success. It teaches just what the steam engineer should know in his engine room about electricity. ^ 12mo, Cloth, 1OO Illustrations. Size 5^x7 9^. PRICE NET A I Sold by booksellers generally, or sent, all charges paid, upon $ receipt of price - - - - _ _- FREDERICK J. DRAKE & CO., Publishers CHICAGO, ILL. Easy Electrical Experiment* and How to Make Them By L. P; DICKINSON This is the very latest and asl| valuable work on Electricity for thgj amateur or practical Electrician putrt lished. It gives in a simple ana easily understood language every thing you should know about Gal- vanometers, Batteries, Magnets, In- duction, Coils, Motors, Voltmeters, Dynamos, Storage Batteries, Simple and Practical Telephones, Telegraph Instruments, Rheostat, Condensers, Electrophorous,' Resistance, Electro Plating, Electric Toy Makiag, etc. The book is an elementary hand book of lessons, experiments and inventions. It is a hand book for beginners, though it includes, as well, examples for the advanced students. The author stands second to none in the scientific world, and this exhaustive work Will be found an invaluable assistant to either th Student or mechanic. Illustrated with hundreds of fine drawings; priote4| On a superior quality of paper. *2mo Cloth. Price, $1.25. Sent postpaid to any address upon receipt of prio 'REDERICK J. DRAKE & CO.. Publishers^ 1 CHICAGO, ILL. Practical Mechanical Drawing and Machine Design Self-Taught By CHARLES WESTINGHOUSE Over 200 Illustrations and 160 Pages. Price, $2 00 A COMPLETE SELF- INSTRUCTOR FOR HOME STUDY on Drafting tools Geometrical defini- tion of plane figures Properties of the circle Poly- gons Geometrical definitions of solids Geometrical drawing Geometrical problems Mensuration of plane surfaces Mensuration of volume and surface of solids The development of curves The development of sur- faces The intersection of surfaces Machine drawing Technical definitions Material used in machine con- struction Shafting Machine design Transmission of motion by belts Horsepower transmitted by ropes Horsepower of gears Transmission of motion by gears Diametral pitch system of gears Worm gearing Steam boilers Steam engines Tables. Frederick J. Drake & Co., Publishers CHICAGO, U. S. A. COMPLETE EXAMINATION QUESTIONS AND ANSWERS FOR MARINE AND STATIONARY ENGINEERS By Calrin F. Swingle, M. E. Author of Swingle's Twentieth Century Hand Book for Steam Engineers and Electricians. Modern Locomotive Engineering Handy Book, and Steam Boilers Their construction, care and management TjTHIS book is a. compendium of ^ useful knowledge, and prac- tical pointers, for all engineers, whether in the marine, or station- ary service. For busy men and for those who are not inclined to spend any more time at study than is ab- solutely necessary, the book will prove a rich mine from which they may draw nuggets of just the kind of information that they are look- ing for. The method pursued by the au- thor in the compilation of the work and in the arrangement of the sub- ject matter, is such that a man in search of any particular item of in- formation relative to the operation of his steam or electric plant, will experience no trouble in finding that particular item, and he will not be under the necessity of going over a couple of hundred pages, either, before he finds it because the matter is systematically ar- ranged and classified. The book will be a valuable addition to any engineer's library, not alone as a convenient reference book, but also as a book for study. It also contains a complete chapter on refrigeration for engineers. 300 pages fully illustrated, durably bound in full Persian Morocco limp, round corners, red edges. PRICE $1.50 _^ N. B. This is the very latest and best book on the subject in print. Sold by Booksellers generally or sent postpaid to any address upon receipt of price by the Publishers FREDERICK J. DRAKE & CO. CHICAGO. U.S. A. Tb