THE 
 
 GAS-ENGINE HANDBOOK, 
 
 A MANUAL 
 
 OF USEFUL INFORMATION 
 FOR THE 
 
 DESIGNER AND ENGINEER. 
 
 BY 
 
 E. W. ROBERTS, M. E., 
 
 Author of The I. C. S. Textbooks on Gas, Gasoline and 
 Oil Engines. 
 
 FIRS T EDI TION. FI RS T THO US AND. 
 
 CINCINNATI: 
 
 THE GAS ENGINE PUBLISHING Co. 
 
 GOODALL BUILDING. 
 

 
 NOTEX 
 
 It is the earnest desire of the publishers and 
 of the author, that this work shall be a standard 
 of reference for those interested in gas enginery. 
 They will, therefore, be pleased to have their atten- 
 tion called to any errors of commission or omission 
 in this book. 
 
 THE PUBLISHERS. 
 
 COPYRIGHT, I9OO, 
 BY 
 
 THE GAS ENGINE PUBLISHING CO 
 
PREFACE. 
 
 It was during the preparation of a series 
 of textbooks on the gas engine for the 
 International Correspondence Schools, that 
 the author was most forcibly impressed 
 with the dearth of matter upon American 
 practice in this motive power. It is a 
 recognized fact that designers on the other 
 side of the Atlantic do not follow methods 
 that meet w r ith the approval of engineers in 
 the United States, yet the only truly valu- 
 able works on gas-engine design that have 
 made their appearance in the Bnglish lan- 
 guage are by English authors. Unhappily, 
 the average gas-engine manufacturer in 
 this country, guards any information he 
 may possess with the jealousy that is 
 scarcely to be explained on ordinary 
 grounds. While there are a number of 
 good works on steam-engine design, the 
 gas engine has been surprisingly neglected. 
 Although the author does not, in the present 
 work, hope to cover the entire subject of 
 gas-engine design he has endeavored to 
 
 435986157 
 
place upon its pages a sufficient number of 
 rules and formulas, to enable any intelli- 
 gent draftsman to design a gas engine 
 without difficulty. Many of the formulas 
 are new and have not appeared in any 
 works by other authors. They have been 
 derived for the most part from tables of 
 dimensions of some of the most successful 
 American-built engines, and have been 
 used by the author in making up his own 
 designs. 
 
 It has been the endeavor, to place within 
 the smallest possible compass a number of 
 useful rules and hints, that may be of value 
 not only to the designer, but also to the 
 engineer who has the care of a gas engine. 
 The chapter on testing has been given 
 more attention than might perhaps have 
 . been thought necessary in a book of this 
 size, but it also covers many points regard- 
 ing the calculation of horsepowers and 
 other items purposely omitted from the 
 other portions of the book. This portion 
 of the work was founded upon the methods 
 employed at the Cornell University. 
 
 The author has drawn, in a few instances, 
 from other works upon the same subject. 
 In preparing the matter on design, he has 
 received many useful hints from the works 
 of Mr. Frederick Grover and Mr. William 
 Norris, the two English writers already 
 
referred to. A part of the data in the table 
 of heat values is from a similar table in 
 the work of Mr. Gardner D. Hiscox. The 
 mechanical tables are from various pocket- 
 books and from the works already referred 
 to. 
 
 Much that the writer would have desired 
 to include in the present work, it has been 
 necessary to omit for lack of space. He 
 has, therefore, given only such matter as he 
 has judged most useful, and which he has 
 found most frequently the subject of in- 
 quiries in the question and answer columns 
 of the technical papers. 
 
 B. W. ROBERTS. 
 
 Cincinnati, March, 1900. 
 
CONTENTS. 
 
 CHAPTER I. PAGE 
 
 Introductory : The principles of opera- 
 tion of the cycles at present in use. . . I 
 
 CHAPTER II. 
 
 Comparison of the Three Cycles : The 
 advantages and disadvantages of each. 13 
 
 CHAPTER III. 
 
 Gas-Kngine Fuels : The principal fuels 
 in use, with a table of heat values. ... 17 
 
 CHAPTER IV. 
 
 Starting and Stopping: The order of 
 procedure in each case 22 
 
 CHAPTER V. 
 
 Care of an Kngine : How to keep a gas 
 engine in good running order 27 
 
 CHAPTER VI. 
 
 Gas-Engine Troubles: Where to look 
 for the cause of trouble, and the rem- 
 edies which apply 35 
 
CHAPTKK VII. TMGE 
 Gasoline Engines : How they differ from 
 a gas engine. Special attachments re- 
 quired for the use of gasoline 41 
 
 CHAPTER VIII. 
 
 Handling a Gasoline Engine : Special 
 rules for the care of a gasoline engine 49 
 
 CHAPTER IX. 
 
 Igniters: Classification of the various 
 devices and examples of the principal 
 types 54 
 
 CHAPTER X. 
 
 Valve Mechanisms : An explanation of 
 the various systems in general use. ... 73 
 
 CHAPTER XI. 
 
 Governors : A classification of the gov- 
 ernor methods. The limitations of 
 each method. Examples of the prin- 
 cipal mechanisms 87 
 
 CHAPTER XII. 
 
 Starters : Devices for starting large en- 
 gines and how they are used 97 
 
 CHAPTER XIII. 
 
 Engines for Automobiles : The chief 
 requisites for engines of this class. 
 The speeds at which they should run. 
 How to avoid vibration. Regulation . 103 
 
CHAPTER XIV. PAGE 
 Gas-Engiiie Diagrams : How to lay out 
 an ideal diagram. How to read a di- 
 agram. Bxamples of good and bad 
 diagrams 108 
 
 CHAPTER XV. 
 
 Gas-Engine Dimensions : How to com- 
 pute the cylinder diameter and the 
 stroke of a gas engine of any size. 
 How to find the speed at which the 
 engine should run 121 
 
 CHAPTER XVI. 
 
 The Cylinder : Rules and formulas for 
 the design of a gas-engine cylinder. . . 129 
 
 CHAPTER XVII. 
 
 Valves and Valve-Boxes : Examples of 
 valve arrangement. Proportions of the 
 various parts of a gas-engine valve. 
 Formulas for valve- box design 136 
 
 CHAPTER XVIII. 
 
 The Piston, the Connecting-Rod and the 
 Crankshaft : Examples of each, and 
 formulas for the proportioning of the 
 various parts 146 
 
 CHAPTER XIX. 
 
 The Engine Frame : An example of a 
 frame for a horizontal engine.. 157 
 
CHAPTKR XX. PAGE 
 Flywheels : How to compute the weight 
 of a flywheel for any gas engine and 
 for any service 160 
 
 CHAPTER XXI. 
 
 Balance-weights : Computations of the 
 weight of a gas-engine counterbalance. 
 Two methods that are in use 167 
 
 CHAPTER XXII. 
 
 Foundations : Materials of which a foun- 
 dation should be built. Formula for 
 computing the weight of an engine 
 foundation 171 
 
 CHAPTER XXIII. 
 
 Miscellaneous Formulas : Formulas for 
 the diameter of the camshaft, the vol- 
 ume of the muffler, the horsepower of 
 a marine engine, the diameter of a 
 screw propeller 177 
 
 CHAPTER XXIV. 
 
 Testing: A full description of all nec- 
 essary operations for a gas-engine test 
 for any purpose, with rules for work- 
 ing up the data obtained 180 
 
 CHAPTER XXV. 
 
 Selection : General rules for the selec- 
 tion of a gas engine 203 
 
TABLES. PAG* 
 
 Heat values of various gases. 
 Capacity of cylindrical vessels. 
 Dimensions of gas and water pipe. . . 208 
 Areas and circumferences of circles. . . .209 
 Index 2I 5 
 
CHAPTER I. 
 
 INTRODUCTORY. 
 
 The Gas Engine, properly so called, is a 
 type of the internal-combustion engine. 
 Its first conception seems to have been by 
 one Abbe Hautefueille, who proposed a mo- 
 tor driven by a gunpowder as early as 1678. 
 From that time until 1862 many proposi- 
 tions were made and some partially success- 
 ful engines were built by various experi- 
 menters. In the latter year, there were 
 already in existence the gas engines of 
 Ivenoir and Hugon, but very wasteful of fuel. 
 In 1862 M. Beau de Rochas, a French en- 
 gineer, made the following propositions, 
 which he embodied in a patent of that date. 
 They were as follows: 
 
 I. The largest cylinder capacity with the 
 smallest circumferential surface. 
 
 II. Maximum speed of piston. 
 
 III. Greatest possible expansion. 
 
 IV. Highest pressure at the beginning of 
 the stroke. 
 
These, he averred, should be the aim of 
 'every gas-engine designer to carry out in 
 his engine. With the exception of propo- 
 sition II, every engine, since the successful 
 .advent of the Otto engine, has been de- 
 signed with these principles in view. Ow- 
 ing to certain practical limitations, high 
 piston speeds have not been found advisa- 
 ble. 
 
 It was M. Beau de Rochas who first pat- 
 ented what is popularly known as the 
 " Otto Cycle." This cycle requires four 
 strokes of the piston for its completion. 
 The first stroke draws in the charge of gas 
 -and air, the second stroke compresses the 
 charge, on the third stroke ignition takes 
 place at the dead point, followed by explo- 
 sion of the gaseous mixture and the expan- 
 sion of the products of combustion, and on 
 the fourth stroke the burnt gases are ex- 
 pelled from the cylinder. This series of 
 operations is that employed by nearly all 
 gas engines in use at the present time. 
 
 This cycle was not put into a practical use 
 in a working engine until, in the year 1876 
 Dr. Abel Otto brought out the first " Otto 
 Cycle " engine, producing a motor which so 
 far surpassed in economy all engines that 
 superseded it as to drive its competitors 
 from the field. This cycle of operation has, 
 because of its being first put into practical 
 
shape by Dr. Otto, been improperly termed 
 the " Otto Cycle," although the credit of its 
 first inception belongs, without question, to 
 M. Beau de Rochas. It is also known as a 
 four-cycle engine, although this term, to be 
 strictly correct, should be four-part cycle, 
 because it consists of the four distinct oper- 
 ations just described. Modern writers have 
 been placing the credit where it belongs, and 
 this series of operations is now generally 
 termed the Beau de Rochas cycle. The au- 
 thor, however, prefers the same descriptive 
 term, " four-cycle," and as such it will be re- 
 ferred to throughout this work. 
 
 The practical operation of the four-cycle 
 engine can be most clearly understood by 
 reference to Fig. I, in which a diagramatic 
 form of the engine is shown with the indi- 
 cator diagram given by the engine placed 
 directly above the cylinder. Since it re- 
 quires two revolutions of the crankshaft K 
 to complete the cycle, the principal points 
 of the cycle are shown on the two circles 
 drawn about the crankshaft as a center. 
 Similar points upon the diagram, the piston 
 travel and the rotation of the crankpin P, 
 are indicated by the same letters. The let- 
 ters indicating points on the piston travel 
 are primed, and those indicating similar 
 points on the crank circle have a double 
 prime. Thus, the point of ignition is indi- 
 
cated on the diagram by B x on the line of 
 piston travel, and by B x/ on the crank circle. 
 Taking the series of operations in their 
 regular order, they are as follows : 
 
 Suction of air from a to A on the outward 
 stroke, compression from A to C on the in- 
 ward stroke, ignition taking place at B, just 
 before the end of the stroke is reached, 
 thus giving a " lead " to the ignition which 
 should just be sufficient to bring the point 
 of maximum pressure D, at the beginning 
 of the next outward stroke ; this lead being 
 necessary because of a lag in the process of 
 ignition, which takes the time required by 
 the piston going from B to C to fully in- 
 flame the charge of gas and air. From D 
 to F the piston is passing 011 a second out- 
 ward stroke, the exhaust-valve X opening at 
 K, just in time to allow the expansion line D 
 F to reach atmospheric pressure at the end 
 of the second outward, or expansion, stroke. 
 The return stroke takes place from F to a, 
 the piston making a second return stroke, 
 driving the products of combustion through 
 the exhaust-pipe by way of the valve X, . 
 completing the cycle. 
 
 A modification of the four-cycle engine 
 was brought out by its inventor, Mr. Du- 
 gald Clerk, in the year 1880. In this engine, 
 using an auxiliary pump, a power stroke 
 was obtained for each revolution of the 
 
crankshaft. The charge was admitted to 
 the engine cylinder under pressure and just 
 at the end of the expansion stroke, driving 
 the exhaust gases out through ports in the 
 sides of the cylinder, which were uncovered 
 by the piston just at the end of the stroke. 
 This arrangement eliminated both the suc- 
 tion and the exhaust strokes required in 
 the regular Beaii de Rochas cycle. Clerk's 
 engine was the pioneer of what is now 
 known as the two-cycle type ; that is, an en- 
 gine which completes its cycle in two revo- 
 lutions of the crankshaft. 
 
 Following the introduction of the Clerk 
 engine came a class of engines which, in- 
 stead of having an auxiliary cylinder to 
 compress the charge, used for that purpose 
 an enclosed crank-chamber. The inward 
 stroke of the piston draws into the crank- 
 chamber the charge of gas and air through 
 a check-valve, and on the outward stroke 
 the charge is compressed. Just before the 
 piston reaches the end of its stroke its end 
 passes an exhaust-port in the side of the 
 cylinder, and in some engines a port lead- 
 ing to the crank-chamber is passed imme- 
 diately afterward. 
 
 In another type, communication was made 
 by means of a poppet valve. The pioneers 
 of this type were the Nash and the Day 
 engines. The former used a mechanically 
 
opened poppet valve, and the latter an ad- 
 mission port in the cylinder wall. Quite a 
 number of engines of the Day type are in 
 successful operation at the present time. 
 
 The principle of the operation of the Day 
 type of the two-cycle engine is shown in 
 Fig. 2, in a similar manner to that of the 
 four-cycle engine shown in Fig. I ; the same 
 method of notation as regards letters being 
 used in this figure, the only difference be- 
 ing that where the two crank circles are 
 used, the inner one indicates the series of 
 operations taking place in the crank-cham- 
 ber, and the outer indicates the series of 
 operations taking place in the cylinder. 
 The piston makes an inward stroke from b 
 to a, causing a partial vacuum in the crank- 
 chamber and drawing the explosive mix- 
 ture through the valve P. On the following 
 outward stroke the mixture in the crank- 
 chamber is compressed to a pressure of 
 about five pounds to the square inch. As 
 the piston uncovers the inlet port S, the 
 pressure within the crank-chamber drives a 
 portion of its contents into the cylinder C, 
 and on the next inward stroke of the piston 
 this charge is compressed, as shown on the 
 diagram from A to C, ignition taking place as 
 in the four-cycle at B, pressure rising to D, 
 the piston making outward stroke, exhaust- 
 ing at E, and the gases reaching atmospheric 
 
pressure again at A, the exhaust-port being 
 opened by being. uncovered by the piston. 
 In the meantime a charge is being drawn 
 into the crank-chamber as before, has been 
 compressed, and the inlet-port S being un- 
 covered immediately after, the contents of 
 the crank-chamber rushing through S is 
 deflected by means of the plate R on the 
 piston to the top of the cylinder, effectu- 
 ally driving the products of combustion 
 through the port M. Returning to the se- 
 ries of operations in the crank-chamber, 
 the port S opens just as the piston reaches 
 the point E, the pressure immediately drop- 
 ping and reaching the pressure of the at- 
 mosphere at about the time port S is closed 
 by the return of the piston. It is unneces- 
 sary to repeat the explanation of the points 
 on the diagram taken from the cylinder C, 
 as they are in all respects similar to the 
 four-cycle engine illustrated in the Fig. i. 
 
 The Clerk engine is no longer built. 
 Nearly all two-cycle engines being manufac- 
 tured at the present time are built after the 
 Day pattern. In the latter part of 1897, a 
 new cycle was brought to the attention of 
 the public. This cycle comprises the se- 
 ries of operations which were the inven- 
 tion of Herr Rudolph Diesel, a German 
 scientist. The Diesel cycle is, like the 
 invention of Beau de Rochas r a four-part 
 
cycle, requiring two entire revolutions of the 
 crankshaft to complete the series of opera- 
 tions. The first, or outward, stroke draws 
 into the cylinder a charge of pure air. On 
 the following return stroke the charge is 
 compressed into a space at the end of the 
 cylinder, equal to about 7 percent of the 
 entire cylinder capacity, the pressure at the 
 end of the stroke being approximately 550 
 pounds per square inch. This high com- 
 pression produces a temperature of the air 
 equal to that produced by the combustion 
 of the fuel, and, in consequence, fuel ad- 
 mitted at the end of this stroke is sure to 
 be ignited as it enters the cylinder. The 
 fuel, whether it be gas, oil or other com- 
 bustible material, is forced into the cylin- 
 der at a pressure higher than that produced 
 by compression, and just as the piston is 
 about to start on its outward stroke. The 
 fuel, burning as it enters, keeps the temper- 
 ature of the cylinder contents up to that 
 produced by compression. After the pis- 
 ton has reached a point of the stroke 
 representing 10 percent of the whole, the 
 fuel is cut off and the products of combus- 
 tion expand. The ensuing return stroke 
 drives the exhaust gases from the cylinder. 
 It is readily seen that, owing to the small 
 compression space, the exhaustion is very 
 much nearer being complete than in those 
 
engines using the cycle of Beau de Rochas, 
 and that but a very small quantity of the 
 products of combustion remain to mix with 
 the fresh charge This series of operations 
 may be better understood by reference to 
 the Fig. 3. 
 
 The same manner of representation is 
 employed as in Fig. i. Suction of a charge 
 of pure air takes places from a to A on the 
 outward stroke, the following inward stroke 
 compressing this charge until the point B 
 is reached, when the fuel is admitted while 
 the piston is passing from B to C and is cut 
 off. The temperature of the gases is con- 
 stant during admission of the fuel, the line 
 from B to C being one of equal tempera- 
 ture known as an isothermal. From C to E, 
 expansion proceeds in a manner similar to 
 that in the original four-cycle engine, the 
 exhaust-valve opening at D and the pres- 
 sure inside the cylinder falling to atmos- 
 pheric at B. The range of temperature 
 from C to D is much greater than that from 
 D to F, in Fig. I, and represents a much 
 higher heat efficiency than that shown on 
 the diagram of the four-cycle engine. 
 
CHAPTER II. 
 
 COMPARISON OF THE THREE CYCLES. 
 
 The four-cycle engine is that most gener- 
 ally manufactured, and it has the advantage 
 over the two-cycle of being more readily 
 controlled. With a properly designed four- 
 cycle engine, the behavior of the gases 
 within the cylinder is known beforehand. 
 The idle stroke gives the cylinder a chance to 
 cool by radiation, no pumps nor enclosed 
 crank-chambers are necessary, and any waste 
 of fuel may be easily remedied. On the other 
 hand, the four-cycle engine must be built in 
 large sizes when compared to the power de- 
 manded of them, the many idle strokes ne- 
 cessitate extremely heavy flywheels and 
 make close regulation most difficult to ob- 
 tain. Furthermore, the operation of the 
 valves occurs but once during two revolu- 
 tions of the crankshaft and necessitates 
 some form of reducing motion between the 
 crankshaft and the camshaft which operates 
 the valves. 
 
 The two-cycle engine is, as a rule, more 
 
wasteful of fuel than the four-cycle engine, 
 and such wastes are more difficult to reme- 
 dy in this type In many of these engines 
 much trouble is experienced with prema- 
 ture explosions, usually called " back- 
 firing," and in the Day type of two-cycle 
 engine the charge quite frequently explodes 
 in the crank-chamber. The bulk of these 
 troubles is fortunately confined to engines 
 built by designers who have an imperfect 
 knowledge of the type, and who fail to de- 
 sign their engines with the proper propor- 
 tions. 
 
 Time should always be given the exhaust 
 gases to fall below the pressure of the 
 crank-chamber before the inlet-port to the 
 cylinder is uncovered. It is also important, 
 when running a two-cycle engine, to re- 
 member that much more heat is being 
 given off through the cylinder walls than in 
 a four-cycle engine of the same power dur- 
 ing the same period, hence the supply of 
 jacket water must be greater in consequence. 
 
 A two-cycle engine will shut down more 
 quickly from lack of water than will a four- 
 cycle. Also, because of the rapid succession 
 of explosions in the cylinder of a two-cycle 
 engine, greater pains should be taken to 
 avoid projections into the cylinder which 
 are not so placed that they may be kept at 
 a comparatively low temperature. 
 
 M 
 
These engines are being better under- 
 stood as the makers gather knowledge from 
 experience, and the above objections have, 
 in several cases, been entirely overcome. 
 So many and manifest are the advantages 
 of more frequent impulses and less weight, 
 both in the engine itself and in the fly- 
 wheels, that the adoption of the two-cycle 
 type is being seriously considered by a 
 number of manufacturers. In fact, the two- 
 cycle engine, for large power-units where 
 the fuel employed is blast-furnace gas, has 
 been in use for some time and found to give 
 satisfaction. Instead of having an enclosed 
 crank-chamber, these engines are supplied 
 with a pump which first drives a volume of 
 pure air through the cylinder, clearing it 
 entirely of the products of combustion re- 
 maining from the previous charge. The 
 fresh mixture follows the charge of pure 
 air, and none of the fuel is wasted, while the 
 clean cylinder increases both the efficiency 
 and the capacity of the engine. 
 
 The Diesel motor is not at present upon 
 the market in sufficient numbers, nor for a 
 length of time, that would make it feasible 
 to draw conclusions of any kind with regard 
 to the future of the engine. The engine is 
 a grand conception theoretically, and the 
 heat efficiency is much higher than that of 
 any heat engine in use. The scheme of 
 
regulation is similar to that which has 
 proven so successful in high-speed steam 
 engines, and it has been shown by actual 
 tests that, in practice, the engine surpasses 
 any other in economy of fuel, and, besides, 
 it is capable of being run with such inex- 
 pensive fuels as the low-grade petroleums 
 classed as fuel oils and selling in quantities 
 for from two to three cents per gallon. The 
 question therefore remains: will the great 
 economy of the motor jtistify the added ex- 
 pense for first cost of the engine? Again, 
 there is the question of repairs and the 
 durability of the engine under the high 
 pressures which it is necessary to sustain in 
 the cylinder. All this remains co be seen. 
 
 16 
 
CHAPTER III. 
 
 GAS-ENGINE FUELS. 
 
 For driving a gas engine, the fuels avail- 
 able are all of those which are in use for 
 other purposes. Many of these fuels need 
 to be transformed into gas before they are 
 available for the gas engine, but many of 
 the liquid and all of the gaseous fuels may 
 be employed directly in the cylinder with- 
 out the necessity of an intermediate proc- 
 ess. There is no fuel not in a gaseous 
 state already that may not be transformed 
 into gas by one of the many processes 
 known to science. The garbage gathered 
 from the streets of our large cities, the 
 waste fat from the slaughter-house, the fat 
 abstracted from wool, as well as all of the 
 animal, vegetable and mineral oils, have 
 been at one time or another transformed 
 into gas which could be used to drive a gas 
 engine. 
 
 The amount of power derived from a cer- 
 tain quantity of fuel is always greater by 3 
 
large amount when the fuel is first made 
 into gas and then used to drive a gas en- 
 gine, than when the fuel is consumed in the 
 firebox of a steam boiler and the power de- 
 rived from a steam engine. Bven with coal 
 as a fuel, if the coal be made into gas and 
 the gas used in a gas engine, it is found 
 that where the very best steam engines 
 give but a horsepower for one hour on i*^ 
 Ibs. of coal, the same amount of fuel has 
 ^iven 1.8 horsepower for one hour. 
 
 The gas-producer which is required for 
 the use of coal in connection with the gas 
 engine, is a much simpler device than the 
 steam boiler, and requires less attention 
 than the latter. There is very little danger 
 of explosion with a gas-producer and gas- 
 engine power plant, and there is usually a 
 supply of gas on hand in the gas-reservoir 
 sufficient to permit the engines to be started 
 at a moment's notice without the necessity 
 of waiting, as when getting up steam for a 
 steam engine. 
 
 Fuels which are most difficult to burn 
 under a boiler, may be turned into gas in a 
 gas-producer. Even gases which are diffi- 
 cult to ignite may be used in a gas engine. 
 For instance, the gas produced during the 
 process of extracting iron from ore in the 
 blast furnace is at times so poor in quality 
 that it may not be used under a boiler, while 
 
 18 
 
when compressed in a gas-engine cylinder 
 it is found to ignite readily. 
 
 The value of fuel for use in a gas engine, 
 is determined in a great measure by the 
 number of heat units produced when a 
 quantity of the fuel is burned. There are, 
 however, several other considerations, such 
 as the pressure derived from the fuel and 
 the percent that may be burned in the gas- 
 engine cylinder. In the process of making 
 gas from fuels a percentage of the heat is 
 employed in liberating the gas, and this, of 
 course, can not be given account of in the 
 gas engine. 
 
 The heat values of the various fuels are 
 given in Table i. It will be seen that the 
 highest heat value is found in natural gas. 
 This is due to the large quantity of marsh 
 gas contained in natural gas. The value of 
 natural gas as a fuel varies, even when the 
 gas is taken from wells very close to one 
 another. It may be said, however, that the 
 natural gas obtained from the wells in west- 
 ern Pennsylvania exceeds in heat value that 
 of the gas in the Ohio fields from Io% to 
 
 Gasoline, in spite of the low heat value 
 per cubic foot of vapor shown in the table, 
 will give, for the same size engine, a power 
 equal to that derived from the best natural 
 gas, and the usual custom is to credit gaso- 
 
line with giving 10% more power than an 
 average quality of natural gas. It is not 
 possible to compute the horsepower to be 
 derived from a certain engine by compari- 
 son of the fuel values, since the gases of 
 low heat value require a smaller quantity of 
 air for their complete combustion, and 
 hence a larger quantity of gas may be taken 
 into the cylinder of the engine at each 
 .stroke. 
 
HEAT VALUES OF FUELS. 
 
 FUEL. 
 
 B. T. U. 
 
 per Ib. 
 
 B. T. U. 
 
 per cu. ft. 
 
 Hydrogen (n 32 F. . . . 
 
 Carbon . ... 
 
 62,030 
 14 500 
 
 343 
 
 Carbon monoxide (CO). 
 Penn. heavy crude oil. . . 
 Caucasian heavy crude oil, 
 Caucasian light crude oil, 
 Petroleum refuse . . . 
 \nthracite gas 
 
 4,396 
 20,736 
 20,138 
 22,027 
 19,832 
 
 2 2A.8 
 
 539 
 
 Bituminous 2fas 
 
 1 d8/l 
 
 
 28-candlepower ilium, gas, 
 19- 
 
 J5- 
 
 New York city water-gas*, 
 London coal gas. . . . 
 
 1 8 448 
 
 950 
 800 
 620 
 710.5 Ave 
 668 
 
 Gasoline and its vapor . . 
 Ethylene C 2 H 4 
 Marsh gas (Methane) C H 4 
 Nat. gas, Leechburg, Pa., 
 Nat gas, Pittsburg, Pa . . 
 
 11,000 
 21,430 
 23,594 
 
 690 
 i,677 
 1,051 
 1,051 
 802 
 
 Acetylene C 2 H 2 
 
 21,492 
 
 868 
 iSs 
 
 
 
 I ^O 
 
 
 
 
 NOTE. The values shown in the above 
 table are given on what is deemed good 
 authority, but they will not be found to 
 agree with all similar tables. 
 
 * Carbureted gas at 60 F. and at 30" water pressure. 
 21 
 
CHAPTER IV. 
 
 /! 
 
 STARTING AND STOPPING. 
 
 Starting a gas engine is a simple oper- 
 ation if a few easily-remembered rules are 
 borne in mind. These rules are briefly as 
 follows : 
 
 A gas engine will not start itself, like a 
 steam engine, and must receive sufficient 
 turning power from an outside source to 
 enable it to take up its cycle of operations. 
 
 The mixture of fuel and air must not be 
 too rich in fuel nor too poor in fuel, for in 
 either case an explosive impulse can not 
 be obtained. More frequently, trouble oc- 
 curs from the mixture being too rich in 
 fuel. 
 
 On large engines the compression should 
 be relieved and the ignition given a nega- 
 tive lead, especially when starting by hand. 
 
 Never attempt to start a gas engine when 
 it is connected to a load, unless it has a 
 powerful starter. 
 
 The ignition apparatus must be in good 
 
working order, and this must be seen to 
 before attempting to start the engine. 
 
 To start a gas engine, it is always a good 
 idea to have a regular order of procedure 
 and to stick to this order so as to avoid the 
 chance of confusion and of omitting some- 
 thing. A good way to proceed is as follows : 
 
 First, oil the engine thoroughly, filling 
 every oil-cup, no matter if one or more is 
 already nearly full. 
 
 See that the ignition appliance is in good 
 order. If it is a tube igniter, bring the tube 
 to the proper temperature (usually a cherry 
 red) and see that the burner is at the right 
 height to keep the tube at the required 
 heat. If an electric igniter is used, unfasten 
 the wire from the insulated electrode and 
 brush it on some part of the engine to see 
 that it gives a good flash. 
 
 If there is a sight plug, it would be well 
 to try the igniter while observing its behav- 
 ior through the hole, or it can be tried by 
 first pressing the points together by means 
 of the igniter mechanism and seeing if 
 there is a circuit by drawing the wire al- 
 ready removed over the end of the insulated 
 electrode, then letting go of the mechanism 
 and determining in the same manner as 
 before if the circuit is broken. 
 
 If these conditions are fulfilled, and when 
 the engine is turned over it is found to 
 
 23 
 
close the circuit on the igniter-points, the 
 igniter is in working order. 
 
 The igniter should be examined periodic- 
 ally and the points cleaned of any accumu- 
 lation of soot or other foreign matter which 
 may occur. The frequency of this exami- 
 nation depends entirely upon the fuel used, 
 and to some extent upon the class of cylin- 
 der oil employed. 
 
 After determining that the igniter is in 
 working order, such oil-cups as can not be 
 conveniently reached when the engine is 
 running should be turned on. 
 
 Next set the starting-cam to start, or open 
 the relief-cock, as the case may be, and if 
 the engine is fitted with a changeable ig- 
 niter, set this also to the starting position, 
 or so that it will fire after the crank has 
 passed the center. 
 
 If the engine is to be started by hand, set 
 the gas-valve open to about one third the 
 opening used when running; usually at a 
 point on the gas-valve dial marked " Start." 
 Then turn the engine over in the running 
 direction until it takes up the cycle, j. e., 
 until an explosion is obtained. 
 
 Next take hold of the gas-valve handle 
 immediately, and open it gradually to the 
 running position as the engine increases in 
 speed. Don't be too precipitate about open- 
 ing the gas-valve, as the engine may get 
 
 24 
 
too rich a mixture and, failing to ignite, 
 slow down and stop. If it shows signs of 
 stopping, close the valve a little at a time 
 until it starts receiving impulses again. 
 While opening the gas-valve with one hand, 
 the other may be occupied in closing the 
 relief-cock, or in throwing the starting- 
 levers to the running position. 
 
 When the engine has reached its full 
 speed, the load may be thrown on, and then 
 the remaining oil-cups must be opened and 
 the water turned on to the water-jacket. 
 
 After the engine has been running a 
 short time, and if the load is very nearly a 
 constant one, the water should be turned 
 on or off until the exit water is of a tem- 
 perature that can just be borne comfortably 
 by the hand. 
 
 If the engine is fitted with a starter, the 
 gas-valve should not be turned on until the 
 engine has made one or two revolutions. 
 The methods of using the starter vary with 
 the several types, and their use will be 
 explained in a chapter on that subject. 
 
 To simply stop a gas engine, it is neces- 
 sary to do no more than turn off the fuel. 
 The order for turning off the oil-cups, etc., 
 should be about the reverse of starting. 
 
 First turn off the gas, and if it is desired 
 to save time in stopping, brake the flywheel 
 with a plank. Then turn off the jacket 
 
water and turn off the gas from the burner, 
 or throw the igniter-switch. If there is 110 
 switch, disconnect one of the wires and 
 hang the end of it up so that a short circuit 
 may not occur. Turn off the oil-cups and 
 drain the water-jacket. This latter proce- 
 dure is not absolutely necessary except in 
 cold weather, but it is not a bad way to 
 prevent the accumulation of sediment in 
 the jacket, and it takes but little time. The 
 habit of draining the cylinder may save the 
 engine at some time when you " didn't know 
 it was going to freeze." 
 
 26 
 
CHAPTER V. 
 
 CARE OF AN ENGINE. 
 
 The proper care of a gas engine should 
 be the pride of every engineer who runs 
 one. In every shop or factory where a gas 
 engine is in use, it should be left in the care 
 of one man and that man should be respon- 
 sible for the condition of the engine at all 
 times. " Everybody's dog is nobody's dog," 
 and so it is with an engine which is left in 
 the care of any man who happens to be 
 about at the time it needs attention. Above 
 all things keep the engine clean, well oiled 
 and with a plentiful supply of water in the 
 tank, when a tank is used, or with sufficient 
 flow of water when connected to a pressure 
 system. 
 
 If the engine is a new one when first re- 
 ceived, it is well to determine the exact 
 point of the stroke where the ignition takes 
 place. This can be done very easily, with 
 an electric igniter, by turning the engine 
 over until the igniter snaps for breaking 
 the circuit, and marking the piston so as to 
 
 27 
 
have a point of reference for future settings 
 of the igniter. All igniter mechanisms 
 wear more or less, and the mark on the pis- 
 ton will avoid the necessity of taking an in- 
 dicator diagram to set the igniter. 
 
 If the piston is so situated as to make it 
 inconvenient to make a mark upon it, the 
 mark may be placed upon the flywheel. To 
 mark the flywheel for this purpose, proceed 
 in one of the following ways : Turn the en- 
 gine over slowly until the igniter just snaps. 
 If the engine has been turned too far it will 
 be necessary to make a complete revolution 
 again in order to be certain that all lost 
 motion is taken up. After the flywheel is 
 in the right position, drop a .plumb-line past 
 the center of the crankshaft and mark on 
 the rim of the flywheel opposite where the 
 line passes it, or level up a straight-edge so 
 that it passes the center of the crankshaft 
 and mark the flywheel as with the plumb- 
 line. It will be more convenient even than 
 the above methods, if the flywheel passes 
 close to some part of the engine-frame or 
 bed, to mark both the wheel and some point 
 on a stationary part of the engine. 
 
 A good grade of machine oil should be 
 used on the engine bearings, but in the 
 cylinder there should always be used an oil 
 that is made expressly for this purpose. 
 Never use the heavy cylinder oils that are 
 
 28 
 
sold for steam-engine cylinders, or you will 
 soon find that the passages are becoming 
 choked with carbon. The proper oil for use 
 in a gas-engine cylinder is a thin lubricant 
 which will not carbonize under the high 
 temperatures present in the gas-engine 
 cylinder. Don't think that because steam- 
 engine cylinder oil costs four times as much 
 as gas-engine cylinder oil, it is four times 
 as good. The direct opposite is true. For 
 an engine with an inclosed crank-case an- 
 other special oil is required and is known 
 to the trade as " crank-case oil." Ordinary 
 oils will churn into lumps in the presence 
 of water and soon become practically use- 
 less as a lubricant. 
 
 It is not a bad practice to make an occa- 
 sional examination of the exhaust-passages 
 in order to determine whether they have an 
 accumulation of carbon in the form of soot. 
 With some gases this deposit does not 
 amount to a great deal, while with others 
 the deposit is such as to in time cause 
 sufficient back pressure to materially de- 
 crease the power of the engine. Should f 
 the water used for cooling purposes contain 
 substances that are likely to cause a deposit 
 of sediment in the water-jacket, the jacket 
 should be cleaned occasionally by means of 
 a long iron rod with a hook on the end, 
 similar to a poker. 
 
 29 
 
Examine all valves occasionally, paying 
 particular attention to the exhaust-valve 
 to see if it is cutting. If they show the 
 least sign of leaking they should be at- 
 tended to at once and ground to a good fit 
 to the seat with flour emery. Never neg- 
 lect a leaky valve, for, once started, the leak 
 will increase rapidly in size. Examine the 
 springs frequently to see that they pull the 
 valves securely to their seats. This can be 
 determined by taking hold of the valve- 
 stem and pulling it back from its seat. The 
 resistance to the pull should be a stiff one, 
 even at the start, for all valves excepting a 
 suction inlet. In the case of an inlet-valve 
 operated by the suction of the piston, it 
 should respond promptly to the vacuum in 
 the cylinder, a very small movement of 
 crank past the center causing it to open. 
 It should be carefully adjusted so that it 
 will seat firmly and yet respond promptly 
 to the vacuum. The gas-valve should also 
 receive its share of attention. 
 
 With engines using electric ignition, the 
 care of the igniter mechanism is one of the 
 most important points. Never neglect the 
 igniter. Much of the prejudice against the 
 electric igniter is the result of improper 
 care of the ignition apparatus. In case a 
 primary cell is used for the battery, a full 
 set of renewals should be kept on hand at 
 
 3 
 
all times and the battery should be renewed 
 before it is too weak. 
 
 In case an ignition-tube is employed, it 
 pays at all times to get the best that can be 
 obtained. Nickel alloy is much the best 
 material to employ for this purpose, as a 
 tube made from the alloy will last, with 
 ordinary care, from six to eighteen months, 
 according to the work the engine has to 
 perform. Wrought-iron tubes have to be 
 replaced anywhere from every two days or 
 so to every two weeks. The shut-down nec- 
 essary while replacing a tube is annoying, 
 to say the least, and it may cause expensive 
 delays. A new tube should be kept in stock 
 at all times, and when tubes that last but a 
 short time are used, it would be well to keep 
 several on hand. 
 
 Do not keep the tube too hot at any time, 
 as a high temperature reduces its strength 
 and makes it wear out so much sooner than 
 it otherwise would. The proper tempera- 
 ture to keep the tube is at a bright cherry, 
 not a white heat. The temperature of the 
 tube for ignition, will vary somewhat with 
 gas of different qualities and the engineer 
 should determine for himself the lowest 
 temperature at which the tube will work 
 successfully. 
 
 If at any time the engineer has forgotten 
 to turn on the jacket water and the engine 
 
begins to throw out volumes of smoke 
 through the open end of the cylinder, turn 
 on the jacket water, but do so with great 
 caution, as, if the cylinder walls are cooled 
 too rapidly, the cylinder may contract be- 
 fore the piston has time to do so, and it 
 may bind the piston so as to materially 
 damage the engine. The cylinder oil-cup 
 ^should also be opened wide at the same 
 time, to give the cylinder an excess of oil 
 and ward off the possibility of its binding. 
 
 Feel of the bearings occasionally, and 
 keep watch of the sight feed of the oil-cups, 
 so that no injury may be done to the engine 
 by cutting of the journals. Don't attempt 
 to cool an overheated bearing with ice un- 
 less you thoroughly understand what you 
 are about. You may get an effect the oppo- 
 site of that desired, and find that the sudden 
 cooling of the outside of the bearing has 
 caused it to grip the shaft like a vise. If 
 the ice can be applied to the shaft itself so 
 as to cause the shaft to contract before 
 the surrounding metal, all trouble may be 
 averted and the desired effect obtained. 
 
 Examine the governor occasionally to see 
 that it is working freely and is not clogged by 
 dirt or any foreign matter. The regularity 
 of motion is dependent as much upon the 
 sensitiveness of the governing device as 
 upon the flywheel. If the governor is a hit- 
 
 32 
 
aiid-niiss, see that the gas-valve is open just 
 far enough to cause an explosion to follow 
 immediately upon the action of the gov- 
 ernor. Nearly all governors of this type 
 use a pick-blade, and if the gas is not turned 
 on sufficiently, the blade will strike or let 
 go according to its method of operation 
 some time before the engine will receive 
 an impulse, and the consequence is a slow- 
 ing down of the engine until the mixture 
 becomes rich enough to produce an ex- 
 plosion. 
 
 If there is a pet cock on the engine having 
 communication with the compression space, 
 the proper state of the mixture may be de- 
 termined by opening the pet cock just at the 
 time of ignition and observing the color of 
 the flame. If the flame is an extremely pale 
 blue, the mixture has too little gas and the 
 gas-valve should be opened a little wider. 
 If, on the other hand, the flame is tinged 
 with red, orange or yellow the mixture is 
 too rich. The proper color of the flame is 
 a deep blue approaching a violet. Do not 
 depend for this test upon a pet cock situ- 
 ated close to the gas-valve opening, as the 
 mixture at this point of the compressior 
 space is usually much richer in gas than at 
 the center. 
 
 At intervals of six months, if the engine 
 is in constant use, remove the piston anc 
 
clean the piston and the inside of the cylin- 
 der with kerosene. Take out the piston - 
 rings and give them and the grooves in 
 which they lie a thorough cleaning as well. 
 The valve-stems should be given an oc- 
 casional spray of kerosene with a squirt can. 
 Never use heavy oil for this purpose, as it 
 will cause the stem to clog and stick. This 
 is especially true of the exhaust- valve stem. 
 
 34 
 
CHAPTER VI. 
 
 GAS-ENGINE TROUBLES. 
 
 While it is not possible to anticipate ev 
 ery trouble that may occur in the running 
 of a gas engine, a general outline of such 
 troubles as are of frequent occurrence, and 
 the remedies that apply in each case, will 
 give a clew to the solution of those prob- 
 lems not considered in this chapter. 
 
 Failure to Start. See first that the fuel- 
 valve is not open too wide, nor that it has 
 not been open a small amount for a length 
 of time that would allow an excess of gas or 
 gasoline to leak into the cylinder. Then 
 examine the igniter. If a tube, see that it is 
 not too cold. If an electric igniter, look it 
 over thoroughly as directed in the chapter 
 on Starting. See if the gas supply is inter- 
 rupted in any way. It may not have been 
 turned on. In cold weather, a gasoline en- 
 gine may fail to start because the gasoline 
 does not vaporize. In this case, warm the 
 air-inlet pipe, or fill the water-jacket with 
 
 35 
 
hot water. In very severe weather it is a 
 good plan to do both. 
 
 Engine Starts, but with W'eak Explo- 
 sion. The igniter may be set too late, and 
 it should be adjusted to ignite just before 
 the engine reaches the rear dead center on 
 the compression stroke. The fuel-valve 
 may not be open wide enough. The engine 
 may lose compression from various causes. 
 One or both of the valves may leak or may 
 not seat itself with sufficient force. The 
 starting lever may be still in the starting 
 position. The relief-cock may be open. 
 The piston may leak, but this is not often 
 sufficient to materially affect the power of 
 the engine. See that the valve springs are 
 not too weak. 
 
 Explosions in the Exhaust Passages. 
 The exhaust-valve may leak or may not seat 
 property. The ignition-tube is too cold, or 
 the electric spark is weak. The fuel -valve 
 may be open too wide, so that, occasionally, 
 the mixture in the cylinder is too rich to take 
 fire. The primary cause of this trouble, is 
 always the occurrence of unburned fuel in 
 the exhaust passages. 
 
 Jingine Slows J)oicn and Finally Stops. 
 This may be due to overheating of the 
 piston or the cylinder, because of an insuffi- 
 cient supply of water, or insufficient oil. One 
 or more of the bearings may be overheated. 
 
 36 
 
notably the crankpin or the crankshaft 
 bearings. The engine may be overloaded. 
 See also the comment under Weak Explo- 
 sion above. For the treatment of an over- 
 heated cylinder or bearing, read the chapter 
 on the care of a gas engine. See paragraph 
 on " Back Firing." 
 
 Explosions Cease. See paragraph on 
 Failure to Start. 
 
 Premature Explosions, " Back Firin^ 
 This trouble is of most frequent occurrence 
 with fuel of a low ignition temperature, 
 such as gases rich in hydrogen, and gaso- 
 line. If the ignition apparatus is properly 
 adjusted, the source of the trouble may be 
 traced to an overheated cylinder and too 
 high compression, or to highly heated pro- 
 jections within the compression space. 
 The latter cause of this annoying trouble 
 has frequently been a puzzle for some of 
 the best gas-engine men to find. A thin 
 projection of metal within the cylinder 
 may be so situated that it becomes heated 
 to a comparatively high temperature and 
 acts in the same manner as an ignition-tube. 
 Again, there may be a projection within 
 the cylinder upon which carbon will deposit 
 in the shape of a cone. This cone of carbon 
 will become incandescent, or nearly so, and 
 cause premature ignition, even as early as 
 on the suction stroke. Projections upon 
 
the piston head such as the heads of fol- 
 lower-bolts, nuts, etc., quite frequently 
 make trouble in this way. In two-cycle 
 engines of the Day type, explosions will 
 sometimes occur in the crank-chamber 
 because of an insufficient fuel supply. 
 
 Flame Blown Out. If in engines of the 
 Otto slide valve type, the flame is frequently 
 blown out and there is no draft to which 
 this trouble may be traced, it is a sign of 
 a leaky slide valve, and that either the 
 springs need tightening or the valve itself 
 needs facing. Should the flame on a tube- 
 igniter be blown out, there is a leak either 
 in the tube itself or in some surrounding 
 part of the engine. 
 
 Spark Gradually Weakens. A spark that 
 is of the proper strength when the engine 
 is started, may gradually get w r eaker after 
 the engine is running, until it is finally too 
 weak to ignite the charge. If the spark is 
 furnished by a battery, this is a sign that 
 the cells need recharging or that the cell is 
 ' not adapted to the work. Battery cells that 
 are made for open circuit only, as those of 
 the sal-ammoniac type, are un suited for 
 gas-engine ignition, because they polarize 
 rapidly and there is not sufficient time for 
 them to recover between the sparks. Occa- 
 sionally a magneto will grow weaker after a 
 few hours use, showing that the magnets 
 
are not strong enough to stand the work 
 required of them. The remedy is to get a 
 better magneto. 
 
 Engine Pounds. -Look the engine over 
 carefully to determine if there are any loose 
 bearings. Lost motion is the prevalent 
 cause of noise in any machine or mechan- 
 ism. If the bearings are " snug," note if 
 the igniter has too much lead, or if prema- 
 ture explosions occur from any other cause. 
 
 Engine does not Develop Full Power. 
 Note what is said in the paragraph on Weak 
 Explosion; then, if the trouble be not 
 found, see if the exhaust passages are 
 obstructed in any way. See also Engine 
 Slows Down. 
 
 Smoke. A black smoke may sometimes 
 be observed issuing from the open end of 
 the piston. In this case the piston is leak- 
 ing. The remedy will suggest itself, upon 
 taking out the piston and examining its 
 condition. If the cylinder is badly out of 
 round it should be rebored. The packing 
 rings may need renewing. See if they are 
 too small to expand to a size slightly 
 greater than the bore of the cylinder. 
 Smoke from the open end of the cylinder 
 may also come from overheating. Smoke 
 issuing from the exhaust-pipe, is due to an 
 excess of fuel in the mixture. 
 
 Leaks. To stop a leak at any point about 
 
 19 
 
the engine, first try tightening up the bolts 
 or nuts that hold the parts. If this does 
 not stop the trouble, and the joint is 
 packed, renew the packing. Should the 
 joint be a ground joint, it should be re- 
 ground with flour emery and oil, and the 
 joint wiped perfectly clean after the opera- 
 tion. The best remedy for a leaky valve- 
 stem is to ream out the bearing and put in 
 a bushing or a larger stem, being careful to 
 see that the stem is in line when the job is 
 complete, and that the bearing centers with 
 the valve seat. 
 
 40 
 
CHAPTER VII. 
 
 GASOLINE ENGINES. 
 
 In general details and appearance, there 
 is little to distinguish between the gas 
 engine and the gasoline engine. The only 
 point of difference being, that a gasoline 
 engine has a special attachment for the 
 purpose of supplying fuel to the engine 
 cylinder, either in the form of vapor or a 
 finely .divided spray. In engines where the 
 compression within the cylinder is carried 
 to the practical limit, it is found that the 
 limit is a somewhat lower pressure for 
 gasoline than for gas of the average quality 
 employed for a gas-engine fuel. A gasoline 
 engine will develop more power than can 
 be obtained from the same engine using a 
 good quality of natural gas. A mixture of 
 gasoline and air will become entirely ignited 
 in much less time than a mixture composed 
 of air and gas. This peculiarity of gasoline 
 produces a much more powerful blow at 
 the beginning of the power stroke, and 
 
usually causes the indicator to show a much 
 higher pressure at this point than is prob- 
 ably present in the engine cylinder, owing 
 to the inertia of the pencil mechanism 
 being too great to allow it to stop when the 
 maximum pressure is reached. A study of 
 gasoline-engine indicator diagrams will 
 show this effect, as illustrated in Chapter 
 XIV. 
 
 Devices for supplying gasoline to the 
 engine, may be divided into three classes; 
 carbureters, vaporizers and jets. 
 
 A carbureter is a device for transforming 
 liquid fuel into a vapor by passing air either 
 over or through a body of the liquid, and 
 carrying off a portion of the liquid in the 
 form of vapor with the air. Carbureters 
 usually operate at ordinary temperatures, 
 but for fuels that have a low specific gravity 
 the air or the fuel and sometimes both, are 
 heated. This mixture of gas and air is 
 usually too rich in fuel to be explosive, and 
 a further addition of air in the engine 
 cylinder is required before it is suited to 
 the w r ork. 
 
 A vaporizer is an appliance for transform- 
 ing into vapor, just the quantity of gasoline 
 that is required for one impulse of the 
 engine and no more, and it differs from the 
 carbureter in not having a supply of vapor 
 constantly on hand. Either the proper 
 
 42 
 
*H* 
 
 Fig. 4. 
 
quantity of fuel is caused to flow directly 
 into the path of the entering air, or the air 
 is passed over a pipe connecting with a 
 small gasoline reservoir and a current of 
 the fuel is induced into the path of the 
 entering air. 
 
 Jets are what the name implies, a jet of 
 liquid usually controlled by a small pump. 
 The pump throws a jet of the liquid into 
 the air pipe so that it strikes the side of the 
 pipe and breaks into a spray, or, as in cer- 
 tain classes of kerosene engines, into a 
 compartment of the compression space and 
 against the side. Jets are sometimes classed 
 as vaporizers, but placing them in a class 
 by themselves makes them much more con- 
 venient to refer to. 
 
 Carbureters may be divided into two 
 classes, surface carbureters and Jittering 
 carbureters. 
 
 In Fig. 4 is shown an example of a surface 
 carbureter. The carbureter is constructed 
 in the form of a spiral in order that the air 
 passage through it may be a long one. The 
 bottom of the carbureter is covered with 
 gasoline to the height ,rjy, and the wicking 
 ww absorbs the liquid so that a large sur- 
 face of fuel is exposed to the air as it passes 
 through. According to Mr. Gardner His- 
 cox, the height of the gasoline should be 
 not over 3 inches and the total height of 
 
 44 
 
p 
 
 Fig. 5- 
 
 4.S 
 
the carbureter not over 8 inches. The air 
 enters the spiral through the clack-valve v 
 and passes to the engine through the pipe e. 
 
 A filtering carbureter is shown in Fig. 5. 
 The air enters the carbureter through the 
 holes h and passes downward through the 
 pipe p to the gasoline, whence it bubbles 
 up carrying with it particles of vapor. A 
 float F carries the pipe p in order that the 
 lower end may be constantly at the same 
 distance below the surface of the liquid. In 
 passing upward, the carbureted air goes 
 through the wire gauze g so any drops of 
 the fuel that may be held in suspension will 
 be caught and left behind. The mixture 
 passes to the engine through the pipe e. 
 
 A good example of a vaporizer is shown 
 in Fig. 6. Gasoline enters the vaporizer 
 through the needle valve n and air through 
 an opening leading to the space A. The 
 double-seated valve A is lifted at each in- 
 duction stroke of the engine, the larger 
 seat opening a passage for the mixture 
 while the smaller seat on lifting opens the 
 passage for the gasoline. As the air is 
 warmed previously to coming in contact 
 with the fuel, it vaporizes readily, and the 
 proportions of gasoline vapor and air may 
 be regulated by the needle valve. 
 
 An example of the jet is shown and 
 described in Chapter IX, see Fig. 9. The 
 
 46 
 
Fig. 6. 
 
 47 
 
method explained in that chapter is one in 
 use in an oil engine and a similar feed is 
 used with a gasoline engine, with the excep- 
 tion that the jet is thrown into the air-inlet 
 pipe, usually against the side. 
 
157 
 
 CHAPTER VIII. 
 
 HANDLING A GASOLINE ENGINE. 
 
 For starting, stopping and the care of a 
 gasoline engine, the same general rules 
 apply as for a gas engine. In starting a 
 gasoline engine, especially when the engine 
 is cold after standing idle for some time, it 
 is a good plan to put a quantity of gasoline 
 in the cylinder and allow it to remain there 
 for about a minute before starting the en- 
 gine. With engines employing a pump to 
 raise the gasoline from a tank or reservoir, 
 it is necessary to operate the pump by hand 
 for a few strokes in order to get a supply of 
 fuel in the reservoir. The fuel supply to the 
 engine is usually regulated by means of a 
 needle valve, which should be carefully 
 cleaned at regular interval-s. In engines 
 using a jet feed, the supply is regulated by 
 adjusting the stroke of the pump, or by 
 regulating the opening in a by-pass, so that 
 a portion of the fuel is pumped through 
 the by-pass and returns to the source of 
 supply. 
 
 49 
 
 HTCov. 
 
With engines using a carbureter, it may 
 be found necessary, in extremely cold 
 weather, to arrange some means of supply- 
 ing heat to it, because the transformation 
 of the fuel into vapor produces a refriger- 
 ating effect which will chill the liquid to 
 such an extent that it will not vaporize. 
 Two methods of heating the carbureter may 
 be employed ; one is to pass the exhaust- 
 pipe through the liquid and the other is to 
 warm the fuel by means of the outgoing 
 jacket water. The latter method is un- 
 doubtedly the most satisfactory as it avoids 
 excessive heating of the gasoline. In kero- 
 sene-oil engines which operate on the car- 
 bureter or vaporizer principle, it is found 
 .absolutely necessary to heat the fuel before 
 it enters the cylinder. In some forms of 
 jet supply, it is not necessary to heat the 
 kerosene before it enters the cylinder, as it 
 is either injected against a highly heated 
 surface or into a body of air that has been 
 brought to a high temperature by compres- 
 sion, as in the Diesel motor. 
 
 The time of ignition in the gasoline 
 engine may be made a little later in the 
 cycle, and thus avoid the hard blow pro- 
 duced at the time of the explosion, without 
 a noticeable loss in power. In starting a 
 gasoline engine, it is often necessary to 
 iirst keep the regulating valve entirely 
 
 50 
 
closed and to open it a little at a time 
 immediately after the engine receives its 
 first impulse. In general, a carbureter will 
 produce a more perfect mixture than the 
 jet or the vaporizer, thus insuring complete 
 combustion and a consequent absence of 
 smoke and odor at the exhaust. But this 
 advantage is, in many engines, offset by the 
 many disadvantages of this method. 
 
 The carbureter usually takes but the 
 lighter portions of the fuel, leaving in the 
 bottom of the tank a residue which is of 
 little or no value, as it is of too low a 
 specific gravity to be used as a fuel in the 
 engine. On the other hand, the vaporizer 
 or the jet insures the using of all the fuel 
 irrespective of specific gravity, if the aver- 
 age of the mixture is equal to that required 
 by the engine. In the occasion of the 
 engine being located near a refinery, it is 
 probable that the residue resulting from 
 the use of a carbureter may be sold at a 
 price that will overcome that objection to 
 this method. In general, however, the 
 vaporizer or jet will be found the least 
 troublesome, although some very successful 
 engines are employing carbureters. 
 
 At no time should there be any foreign 
 matter permitted to enter the gasoline- 
 supply pipes or the valves. Gasoline tanks 
 should be filled through a fine-wire strainer 
 
or a piece of closely woven muslin. The 
 opening of the supply-pipe into the tank 
 should be covered with a strainer and every 
 precaution taken to prevent trouble from 
 this source. Never put the gasoline in 
 anything but a perfectly clean receptacle. 
 Old paint or varnish cans or barrels are 
 especially to be avoided. At regular inter- 
 vals, drain the gasoline tank and clean it 
 thoroughly. Where the tank is under 
 ground or in a similar position, in which 
 it would be impractical to clean it, extra 
 precaution should be taken to avoid the 
 entrance of foreign matter. Much of the 
 trouble experienced with gasoline engines 
 occurs from neglect of this precaution. 
 
 Large quantities of gasoline should be 
 stored at some distance from buildings, 
 and the tank should be protected from the 
 direct rays of the sun by means of a shed or 
 a covering of earth. If the tank is made of 
 sheet iron and fitted with a safety valve 
 that will allow the escape of the vapor, so 
 that the pressure induced by overheating 
 may be relieved before endangering the 
 tank, much of the loss by evaporation will 
 be avoided. Many gasoline-tank explosions 
 are due to excessive pressure caused by the 
 overheating of a tightly closed receptacle, 
 and not from the application of a flame. 
 Usually, the evaporation of this light 
 
hydrocarbon is so rapid that all air is 
 driven from the vacant space above the 
 liquid and a flame applied to an outlet of 
 the tank would not cause an explosion, as 
 the mixture would be too rich. 
 
 If, by any mishap, a tank of gasoline takes 
 fire at a small outlet, run to the tank and 
 not away from it, and either blow or pat the 
 flame out. Never put water on burning 
 gasoline or oil, for the oil will float on top 
 of the water and the flames spread so much 
 the more rapidly. Throw fine earth, sand 
 or flour on top of the burning liquid. Flour 
 is best, because it will float and less will be 
 needed. The best fire-extinguisher for a 
 fire of this sort in a room that may be 
 closed is ammonia. Several gallons of 
 ammonia, thrown in the room with such 
 force as to break the bottles which contain 
 it, will soon smother the strongest fire if 
 the room be kept closed. Very often, 
 simply striking the opening from which 
 the flame is issuing, with the palm of the 
 hand will put out the fire. 
 
CHAPTER IX. 
 
 IGNITERS. 
 
 A good igniter is one of the most impor- 
 tant parts of a gas engine. It is required 
 of an igniting device: that it shall fire 
 every charge without fail, that it shall 
 ignite the charge at the proper point of the 
 cycle, and that it shall require a minimum 
 amount of attention both for cleaning and 
 renewal of parts. There are four distinct 
 ways in which the charge may be ignited 
 I. Ignition by means of a naked flame. 
 II. Contact with a surface which is at 
 high temperature. 
 
 III. The flame of a small electric arc. 
 
 IV. Raising the temperature of the cylin- 
 
 der contents by high compression. 
 Flame ignition has its best known example 
 in the Otto slide-valve engine. The general 
 principle involved is, however, much better 
 illustrated in Barnett's igniting cock, Fig. 
 7. In this method of ignition two gas jets 
 are necessary. One, the flame f which is 
 
 54 
 
Fig. 7. 
 
 55 
 
employed for ignition of the charge, and 
 the other F for relighting^" when blown out 
 by the explosion within the cylinder. The 
 plug valve A is shown in the proper posi- 
 tion for relighting the flame f. At the right 
 moment, the valve makes a quarter turn so 
 that the opening in the plug is opposite 
 the opening into the cylinder indicated by 
 the dotted lines. The resulting explosion 
 extinguishes the flame f, and the valve .re- 
 turns to the position shown in the figure, 
 the gas rushes out through the opening and 
 ignites at the flame F. 
 
 Contact with a highly heated surface 
 finds its best example in the hot tube. In 
 several makes of kerosene oil engines, a 
 portion of the cylinder is divided from the 
 remainder by a narrow passage and left 
 unjacketed, so that it reaches a tempera- 
 ture sufficiently high to ignite the charge. 
 Another plan, due to Mr. Dugald Clerk, is 
 to drive the charge through a grate built of 
 thin strips of platinum. The grate is 
 brought to the proper temperature by 
 means of an exterior flame before the 
 engine is started and, thereafter, the grate 
 receives sufficient heat from the burning 
 gases to ignite the following charge. This 
 method is useless in a hit-and-miss type of 
 engine, because a few idle strokes will allow 
 the grate to cool to a temperature below 
 
 56 
 
57 
 
that necessary for ignition. Thin rods and 
 even small bolts have been employed in 
 much the same manner as the platinum 
 grate. 
 
 The earlier tube igniters used what is 
 known as a timing valve. This valve 
 opened communication with the tube, so as 
 to time the ignition at the proper point of 
 the cycle. It is now the common practice 
 to time the firing point automatically by 
 the compression of the charge. When the 
 engine exhausts, the pressure within the 
 tube falls to that of the atmosphere, and it 
 is filled with the products of combustion. 
 When the engine compresses a fresh charge, 
 a portion of the mixture is driven into the 
 ignition tube, forcing the products of com- 
 bustion ahead of it, and when the pressure 
 within the cylinder has reached the right 
 amount, the fresh mixture is brought into 
 contact with the heated portion of the tube 
 and ignites. A tube of this kind with 
 adjustable burner, is shown in Fig. 8. The 
 tube is shown at t, and it should be of 
 either nickel alloy or porcelain. The gas 
 is driven by the compression of the piston 
 into the tube through the port p. The tube 
 is heated by the Bunsen burner b, the flame 
 entirely surrounds the tube and is confined 
 by means of the chimney c. The chimney 
 is lined with a tube of asbestos, the asbestos 
 
being an important addition, as it prevents 
 the heat from being carried off through the 
 walls of the chimney. Minute adjustments 
 of the flame may be obtained by swinging 
 the burner b about the set-screws s, while 
 for larger movements the chimney and the 
 burner may be changed by loosening the 
 screw y and sliding the chimney along the 
 rod r. A pet-cock is provided at g for 
 blowing the soot from the tube. In general 
 the flame and the chimney are not made 
 adjustable, their proper position having 
 been determined by experiments at the 
 factory, and the chimney and burner being 
 fastened in the position found most favora- 
 ble for the operation of the engine. 
 
 Ignition by contact with a hot surface in 
 the combustion chamber, is illustrated in 
 Fig. 9. This set of diagrams shows the 
 series of operations which take place in the 
 Hornsby-Akroyd oil engine. Before start- 
 ing the engine the chamber c is brought to 
 a temperature very nearly that of a red heat 
 and this temperature is afterwards main- 
 tained by the combustion within the cylin- 
 der. During the suction stroke of the 
 engine, a jet of oil is forced into r by means 
 of a pump and, striking the hot surface of 
 the chamber, it is transformed into vapor. 
 The cylinder of the engine when the piston 
 is at the end of the suction stroke contains 
 
 59 
 
pure air, while the chamber c is filled with 
 oil vapor and products of combustion left 
 from the last cycle. In the figure, the oil 
 is represented by small circles and the air 
 by crosses, while the products of combus- 
 tion are shown by small squares. In dia- 
 gram (B) the piston has compressed the air, 
 driving it into c and, as soon as the con- 
 tents of the chamber is of an explosive 
 nature, it takes fire from the heated surface 
 of c. In diagram (D) the piston has started 
 on a forward stroke, expanding the products 
 of combustion. 
 
 The electric igniter is slowly but surely 
 taking the place of all others, because only 
 by its use can the ignition of the charge be 
 timed to a certainty. The form of electric 
 igniter which is in most general use, op- 
 erates upon the following principle: An 
 electric circuit from a battery or other 
 source of electrical energy is closed, by 
 means of contact points within the com- 
 pression space, through an inductive resist- 
 ance in the form of a spark coil. Upon 
 breaking the circuit, the inertia produced 
 by the induction raises the pressure of the 
 circuit and causes a hot spark to arc across 
 the terminals. This method is known as 
 the make-aiid-break, and it may be pro- 
 duced either by forcing the two contacts to- 
 gether and then throwing them suddenly 
 
 61 
 
00- 
 
 Fig. 10. 
 
apart by means of a spring, or by wiping one 
 contact on the other in a manner that is 
 known as the wipe break. This latter 
 method produces a very hot spark, but pro- 
 vision must be made for adjustment as the 
 points wear out quite rapidly. 
 
 In either method, good judgment must 
 be used in adjusting the current supply to 
 the requirements of the ignition device. 
 Too little pressure will produce but unsat- 
 isfactory ignition, while, should the pres- 
 sure be such that the current will be large, 
 the contact points will wear out in a very 
 short time. Where the battery employed 
 is of low resistance, as in the case of a 
 storage cell, the pressure at the battery 
 terminals should be much less than with 
 cells having a high internal resistance. 
 Two methods are available for reducing the 
 rapid destruction of the points by too large 
 a flow of current, when it is inadvisable to 
 reduce the number of cells. The destruct- 
 ive action of the spark may be annulled by 
 placing a condenser in parallel with the 
 break as shown in Fig. 10, or by putting a 
 noninductive resistance in series with the 
 circuit as shown in. Fig. loa. To make a 
 noninductive resistance, wind the wire in a 
 coil, about a core that contains 110 iron, and 
 begin to wind at the center of the length of 
 wire so that, when finished, one half the 
 
 63 
 
6 4 
 
current will flow in one direction around 
 the coil, and the remaining half in the 
 opposite direction. If the resistance coil is 
 not made iioninductive, it will be quite 
 sure to destroy the sparking power of the 
 spark-coil. 
 
 An example of the first style of make- 
 and-break is shown in Fig. n. This figure 
 is diagrammatic only and is not intended to 
 represent any special make of igniter. From 
 a source of energy B, one wire is grounded 
 on the frame of the engine. The other side 
 of the circuit is attached to the insulated 
 electrode e, and it contains the spark coil c 
 connected in series. The cam C, rotated in 
 the direction of the arrow, depresses the 
 spring s which carries with it the electrode 
 p until the point of p meets e. Further 
 rotation of the cam merely deflects the 
 spring, increasing the pressure between the 
 contacts. Still further rotation of the cam 
 allows the end of the spring to slip off the 
 lip and it flies back, carrying with it the 
 plunger />, making a quick break between 
 the contacts and producing the spark. In 
 practice, much trouble is experienced with 
 flat springs as they are more liable to break 
 than are helical springs. Note that by 
 helical spring is meant a spring that is 
 wound in the form of a screw thread as 
 shown at A, Fig. 12. This form of soring is 
 
 65 
 
bfl 
 
 s 
 
 66 
 
:>ften but erroneously called a spiral spring. 
 The true spiral spring is shown at B in the 
 figure, and is of the kind so much used in 
 clocks ; it is not so reliable as the helical 
 spring. 
 
 An example of a wipe break is shown in 
 Fig. 13. The electrodes X and Y are so 
 placed that they lie directly in the path of 
 the incoming gases in order to keep the 
 electrodes cool. The electrode Fis rotated 
 by the crank E, and rubs against the spring 
 electrode. The rubbing has the advantage 
 that it keeps the contact surfaces always 
 clean. The electrode Fis made adjustable, 
 so that it can be pushed further into the 
 valve box as it wears off. A very hot spark 
 is produced by this form of break and,, 
 although it requires more frequent adjust- 
 ment and renewal of parts than some other 
 forms, there is no platinum used, so that it 
 is quite a favorite with some designers. It 
 should be borne in mind by the designer 
 that, in both these forms of make-and- 
 break igniters, contact must be made with 
 pressure and the break must be a quick 
 one. 
 
 Another method of electric ignition that 
 is finding great favor, especially among 
 automobile builders, is the jump-spark. 
 This spark is so called because it will arc 
 or "jump" across an air gap without pre- 
 
 67 
 
68 
 
viously bringing the terminals into contact. 
 It is produced by means of an induction 
 coil, or a RuhmkorfF coil as it is sometimes 
 called. In this coil there are two windings, 
 one of comparatively coarse wire wound on 
 a core of iron wire, and a coil of much finer 
 wire w T ound on the outside of the coarse- 
 wire coil. The current from the source of 
 energy is allowed to flow through the 
 coarse or primary winding, and any varia- 
 tion in the strength of the primary circuit 
 will induce a current in the fine wire form- 
 ing the secondary circuit. In a Ruhmkorff 
 coil the secondary current is usually pro- 
 duced by rapidly opening and closing the 
 primary circuit, either by means of a 
 magnetic vibrator or by a toothed wheel. 
 This method produces a series of sparks 
 across any gap in the secondary circuit that 
 is not too great for the capacity of the coil. 
 Sparks are produced both on closing the 
 primary circuit and when it is broken, but 
 the spark at the break is much the more 
 powerful of the two. The induction coil is 
 used in two ways. In one the vibrator is 
 employed and, upon closing a switch on 
 the cam shaft, a series of sparks is sent 
 across the spark gap in the combustion 
 space. In the other, 110 vibrator is used, 
 and two sparks are produced, one on the 
 opening and one on the closing of the 
 
 69 
 
b/J 
 S 
 
switch. The second spark is that which is 
 depended upon for igniting the charge, as 
 the make spark is not strong enough. 
 
 The arrangement of the circuits for pro- 
 ducing the jump-spark is shown in Fig. 14. 
 The primary circuit passes through the 
 switch S on the cam shaft to the primary of 
 the coil, through the primary and thence 
 back to the source of energy B. The sec- 
 ondary circuit is from the terminal a of the 
 secondary to the terminal x of the ignition 
 plug and from the terminal y of the ignition 
 plug to the terminal b of the secondary. 
 For the secondary circuit, the secondary 
 winding of the coil becomes the source of 
 energy. If there is a vibrator in the circuit, 
 the time of ignition will be immediately 
 after the switch closes the circuit. If there 
 is no vibrator in the circuit, the time of 
 ignition will be just as the switch breaks 
 the circuit. To get a sure ignition, it has 
 been found that the points should be set a 
 distance apart equal to about one quarter 
 the maximum sparking distance of the coil. 
 A 3^-inch coil with a J^-inch gap has been 
 found to give very good results. There are 
 coils on the market designed expressly for 
 gas engines using the jump-spark, and the 
 author strongly advises the reader to buy a 
 coil rather than attempt to make it himself; 
 for the reason that considerable skill and 
 
experience is requisite for the design and 
 construction of a coil which will stand the 
 hard service required of it when used for 
 gas-engine ignition. 
 
 Raising the temperature of the cylinder 
 contents is a method that has proven quite 
 successful in the Diesel motor, and for a 
 description of this method the reader is 
 referred to Chapter I. 
 
 72 
 
CHAPTER X. 
 
 VAI^VK MECHANISMS. 
 
 The usual form of valve used in a gas 
 engine is that known as the mushroom 
 type and is shown in Fig. 29, Chapter XVII, 
 where the general proportions of the valve 
 are treated. The reason that this type of 
 valve is best for the gas engine, is because 
 there are no rubbing surfaces and there is 
 very little wear. The high temperature 
 within the cylinder of the gas engine, 
 makes it difficult to keep the valves and 
 their seats at a pressure at which they will 
 wear for any reasonable length of time. 
 Hot gases of themselves, when passing at a 
 high rate of speed through a small opening, 
 score the metal surrounding the opening, 
 and, for this reason, if a hole is once started 
 it enlarges rapidly and soon the engine is 
 not working at its full power. 
 
 In nearly all gas engines of the four-cycle 
 pe, the valves are operated by means of 
 ams on a shaft called the lay- or camshaft, 
 
 73 
 
which makes one revolution to two of the 
 crankshaft. Occasionally the use of the 
 camshaft is avoided by employing as pecial 
 mechanism in connection with an eccentric, 
 in which the eccentric rod is made to open 
 the valve at every other stroke, the interme- 
 diate strokes being idle ones. In an engine 
 manufactured in England, a rotating valve 
 is employed which is on a shaft making 
 one revolution to four revolutions of crank- 
 shaft. The valve ports are so arranged 
 that they are open to the cylinder twice in 
 each revolution of the valve-shaft. 
 
 In many small engines, only the exhaust 
 valve is opened by mechanical means, the 
 inlet valve being operated by the suction 
 of the engine. This of necessity causes 
 some wire-drawing during the suction 
 stroke, as there must be a partial vacuum 
 in the cylinder before the valve will operate. 
 On large engines, wherein a small propor- 
 tionate loss of power becomes of impor- 
 tance, it is not advisable to employ the 
 suction valve, and the inlet valve should 
 be operated in the same manner as the 
 exhaust valve. In fact, some gas-engine 
 designers claim that a suction valve will 
 give trouble because, if it sticks at all, the 
 valve opening is sure to be reduced, while 
 with a mechanically operated valve, a little 
 extra friction is of no consequence. There 
 
 74 
 
75 
 
are, however, some very good engines and 
 a few large ones which have been operating 
 for several years- with suction valves. The 
 only advantage the author can see in such 
 a valve is simplicity and less first cost, be- 
 cause of the absence of the valve mech- 
 anism. 
 
 In two-cycle engines of the Day type, the 
 only valve required for either the exhaust 
 or the inlet, is a check-valve opening into 
 the crank-chamber. For a description of 
 this engine and the valve arrangement the 
 reader is referred to Chapter I. The check- 
 valve will cause a slight wire-drawing in 
 the crank-chamber, but, with a properly 
 proportioned engine, there is no vacuum 
 formed in the cylinder at any portion of the 
 stroke. 
 
 It is customary, in the design of a valve 
 mechanism, to transmit motion from the 
 cam to the valve-stem by means of a lever 
 in order to avoid cramping of the valve- 
 stem in its bearings. If, however, the 
 valve-stem be given a bearing near the cam 
 with a long surface and the stem be en- 
 larged if necessary in order to stiffen it, the 
 intermediate lever may be omitted. A valve- 
 operating device with a lever is shown in 
 Fig. 15. The lever L is pivoted at x and 
 carries the roller r which bears against the 
 cam C. The center of gravity of the lever 
 
 76 
 
L is placed far enough to the right of x 
 that the lever will incline toward the cam 
 after it has been thrust by the valve -stem s 
 as far as allowed by the head of the valve. 
 The hardened steel contact piece a is put 
 in the end of the valve-stem and a hard- 
 ened plate b is dovetailed into the lever. 
 
 In Fig. 16 is shown a valve-stem without 
 the lever. The stem is screwed or keyed 
 into the sliding block B, which is forked on 
 the end so as to provide a bearing for the 
 shaft of roller r. If the camshaft rotates 
 constantly in one direction, the center line 
 of the camshaft should be set out of line 
 with the roller shaft as shown in the figure. 
 The direction in which the shaft c should 
 be out of line is determined by the direc- 
 tion of motion of the camshaft. The line 
 w v should be on the side of x y opposite 
 the projection on the cam, when the pro- 
 jection is approaching the roller. 
 
 In laying out a cam, the simple method 
 shown in Fig. 17 will give an outline that 
 is suitable for nearly every condition. The 
 cam is made up of two parts, a portion C 
 concentric to the shaft, and the eccentric 
 portion P. The part C is usually turned a 
 little smaller than the circle shown by the 
 dotted line, which is a circle that would be 
 described by the roller when the valve is 
 down upon its seat and all lost motion 
 
 73 
 
79 
 
is taken up between the stem and any 
 mechanism which carries the roller. In 
 laying out the eccentric portion, it should 
 be remembered that the valve does not 
 begin to open until the point/, where the 
 line m n meets the dotted circle, is in con- 
 tact with the roller. That portion of the 
 revolution of the cam during which the 
 valve is to remain open, should, therefore, 
 be laid off on the dotted circle and not, as 
 the author has seen it done, on the concen- 
 tric outline of the cam. The arc P is 
 usually so laid out for the exhaust-valve, 
 that it will open the valve when the piston 
 has completed about .9 of the working 
 stroke and close it just as the exhaust stroke 
 is completed. Hence, for the exhaust cam 
 the arc P should be i.i times a quarter cir- 
 cle or 99, say 100 in round numbers. After 
 laying off 100 on the dotted circle, draw 
 tangents through p and q to the circular 
 outline of the cam, meeting it in the points 
 m and/. Lay off the radial distance / equal 
 to the movement of the roller when it is 
 operating the valve, and describe the arc n 
 k slightly rounding the corners at n and k. 
 For the inlet cam the arc P is usually 
 slightly under 90 in order that it may not 
 open the inlet valve before the piston starts 
 on the suction stroke nor hold it open after 
 the compression stroke has begun. The 
 
 80 
 
bo 
 
 S 
 
designer should exercise his judgment to 
 some extent in this matter, but he will find 
 85 to be very close to the proper length of 
 the arc. For the gas valve, a great many 
 designers use the same cam as for the air 
 valve. In any case, the time that the gas 
 valve should remain open is practically the 
 same as for the air valve, some engines be- 
 ing governed within limits by varying the 
 time during which the gas valve remains 
 open. 
 
 An example of a valve operating mechan- 
 ism in which there is no camshaft, is shown 
 in Fig. 18. In the figure, ^ is the exhaust- 
 valve stem. The slide W^ reciprocated by 
 the eccentric E on the crankshaft C, car- 
 ries a toothed wheel X. To the wheel A' is 
 pinned the ratchet wheel Y which has just 
 twice the number of teeth that are on A". 
 At each stroke of the slide W, made in the 
 direction of the crankshaft, the pawl p 
 rotates the wheels X and Y so that a tooth 
 T and a notch jVare presented alternately 
 to the stem s. Hence the valve is opened 
 but once during two revolutions of the 
 engine. It is claimed by those manufactur- 
 ers who employ this and similar devices, 
 that the valve opens much more quickly 
 than with the cam, and a better perform- 
 ance of the engine is obtained in conse- 
 quence. There are several varieties of 
 
 82 
 
valve-motion dependent upon an eccentric 
 and a device similar to that shown in Fig. 
 18, nearly all of which are the same in prin- 
 ciple as the device shown. A number of 
 devices for avoiding the two-to-one reduc- 
 tion have been patented, a few of which are 
 in use, but the majority of the four-cycle 
 engines are using the camshaft. 
 
 For transmitting motion from the crank- 
 shaft to the camshaft, there are three kinds 
 of gears employed the ordinary spur gear, 
 the bevel gear and the skew gear. The 
 spur gear is that which has its teeth on the 
 periphery of a disk, and is used for trans- 
 mitting motion between shafts which are 
 parallel. It is the most familiar of the 
 three. The bevel gear has its teeth on the 
 surface of a cone and is used for transmit- 
 ting motion between shafts at an angle but 
 which lie in the same plane. The skew 
 gear is one in which the teeth are in the 
 form of a screw thread or helix a screw 
 with a multiple thread and is used for 
 transmitting motion between shafts which 
 are at an angle and which do not lie in the 
 same plane. 
 
 Examples of these three varieties of gear 
 
 are shown in Fig. 19. At (A) is shown a 
 
 pair of spur gears for transmitting motion 
 
 from the crankshaft s to the camshaft S f 
 
 . and at the same time reducing the velocity of 
 
 83 
 
S 4 
 
5 to half that of s. The size of pinion p is 
 made one-half that of the gear <7, in order 
 to make the proper reduction in speed. 
 The two shafts are parallel. At (B) is shown 
 a pair of bevel gears for changing the 
 direction of motion and at the same time 
 making the two-to-one reduction. The 
 shafts lie in the same plane, that is to say, 
 straight lines, as x y, p q, etc., may be so 
 drawn as to pass through the centers of the 
 two shafts. At ( G) is shown a pair of skew 
 gears in which the speed reduction may be 
 made without making the slower rotating 
 gear the larger. In fact, the gear on the 
 camshaft may be, and usually is made 
 smaller than that on the crankshaft. An- 
 other advantage is that the two shafts do 
 not lie in the same plane. Motion may be 
 transmitted with these gears without the 
 noise that is more or less evident when the 
 spur or the bevel gear is used. 
 
 Engines, which are fitted with spur gears, 
 usually have the camshaft near the crank- 
 shaft, and the valve-stems project from the 
 valve boxes in a direction parallel to the 
 axis of the cylinder. This arrangement 
 necessitates either long stems on the valves, 
 or a long rod from the camshaft to the end 
 of the valve-stem. In some engines, this 
 feature is avoided by the use of a train of 
 spur gears which brings the camshaft close 
 
to the valve boxes. In a carefully designed 
 engine, there is 110 objection to the use of 
 spur gears, and their use often saves ex- 
 pense in construction. 
 
 Very few engines employ the bevel gear, 
 as it is a somewhat difficult matter to so 
 arrange them on the engine that they will 
 not take up an undesirable amount of room. 
 The skew gear obviates this latter difficulty 
 to a great extent, and it allows the cam- 
 shaft to be placed in a position from which 
 it is more convenient to operate the valves. 
 Either gear may be used to operate a cam- 
 shaft the axis of which is parallel to the 
 axis of the cylinder,. and by the use of the 
 second pair of gears the shaft may be given 
 a second quarter turn and run across the 
 back of the cylinder head to operate valves 
 that are placed in the head. Where there 
 are two or more cylinders, it will add to the 
 economy of construction, if a single cam- 
 shaft is employed to carry all the cams. 
 This shaft should then be placed so that 
 the axis is at a right angle to the axes of 
 the cylinders. 
 
 86 
 
CHAPTER XI. 
 
 GOVERNORS. 
 
 All gas engines are governed by eitlier 
 cutting out or cutting in impulses to the 
 piston, or by reducing or increasing the 
 force applied the piston according to the 
 requirements. Regulating the speed of the 
 engine by varying the number of impulses 
 given to the piston is called the hit-and-miss 
 system. There is no term at present in use 
 that will cover all cases of governing by 
 varying the strength of the impulse, and 
 the author suggests the term variable 
 impulse. There are three methods of gov- 
 erning under each of the above two systems 
 of regulation, as described below. 
 
 HIT-AND-MISS. 
 
 I. Holding the gas valve closed during 
 one or more revolutions of the engine when 
 running below full power. During the idle 
 strokes the engine is compressing and 
 expanding a charge of pure air. 
 
 87 
 
II. Stopping the action of the exhaust 
 valve, holding it either open or closed dur- 
 ing the idle strokes. When the valve is 
 held open there is not sufficient suction to 
 open the inlet valve, this method usually 
 being employed on engines having a suc- 
 tion valve. In the latter case the engine 
 retains the products of combustion, the 
 pressure within the cylinder being at all 
 times too great to allow a fresh charge to 
 enter. 
 
 III. Cutting off the current from the 
 igniter, employed, of course, where an 
 electric igniter is used. The governor is, 
 in this case, attached to a switch, which is 
 opened whenever the speed passes the 
 limit. In this case the charge is alternately 
 compressed and expanded until the switch 
 is closed and ignition takes place. 
 
 A fourth method might be added to this 
 class, i. e., the stopping of the camshaft. 
 With this method all operations are halted, 
 usually with the exhaust valve held open. 
 
 VARIABLE IMPULSE. 
 
 IV. Partial stoppage of the gas supply. 
 The mixture of fuel and air retains its 
 explosive properties within certain limits of 
 the proportion between the two. If the 
 mixture is poor in gas the impulse is cor- 
 respondingly weakened, and up to the point 
 
 88 
 
whereat the charge explodes with the 
 greatest force, the strength of the impulse 
 may be increased. There is also a lower 
 limit, beyond which the mixture becomes 
 so poor in gas that it will not explode. 
 After passing this limit it is necessary to 
 resort to the hit-and-miss method I, and 
 cut out the gas supply entirely. ' 
 
 V. Throttling the charge. This method 
 reduces the strength of the impulse by 
 reducing the quantity of the charge that 
 enters the cylinder, the proportions of fuel 
 and air remaining the same at all times. 
 
 VI. Varying the point of ignition. The 
 greatest ' mean effective pressure in a gas 
 engine is obtained when the spark has 
 sufficient lead to bring the maximum pres- 
 sure at the beginning of the stroke. If the 
 lead is reduced, or made negative (ignition 
 delayed until the crank has passed the 
 center), the strength of the impulse may 
 be varied. 
 
 Hit-and-miss regulation is that which 
 gives the greatest economy of fuel con- 
 sumption. There is little choice between 
 the three methods given above, as all have 
 advantages and disadvantages that make 
 them about equally good. 
 
 Of the variable impulse methods, No. IV 
 is that which gives the best fuel economy, 
 the compression is the same at every 
 
cycle. The objection to this plan is, the 
 return to the hit-and-miss system as 
 soon as the speed falls to the limit below 
 which the charge would be too poor in gas 
 to explode. Method V has been used quite 
 successfully for engines driving dynamos, 
 but it does not give the economy that is 
 derived from an engine employing one of 
 the first four methods. The method de- 
 scribed last, is perhaps the most wasteful of 
 fuel after the lead is late enough to form a 
 perceptible reduction in the area of the 
 indicator diagram. The result obtained is 
 shown very plainly in the chapter on indi- 
 cator diagrams. This method of speed 
 regulation is of little service where econ- 
 omy is desired, but where economy is a 
 secondary consideration, as in an automo- 
 bile engine, it is a very simple method of 
 governing. 
 
 Governors of three different kinds are 
 employed on gas engines. Two of these 
 are of the centrifugal type, similar to the 
 governors in use on the steam engine, the 
 other is a governor made possible by the 
 hit-and-miss system of regulation and is 
 known as the pendulum or inertia governor. 
 The centrifugal governors are the conical 
 pendulum and the shaft governor. Hither 
 of these two may be employed for any 
 method of regulation while the pendulum 
 
 90 
 
governor may he used only for the hit-and- 
 miss. 
 
 An example of the conical pendulum gov- 
 ernor is shown in Fig. 20 as arranged to 
 operate a throttling device. The two balls 
 bb are rotated from the camshaft, or other 
 convenient revolving portion of the engine, 
 through the bevel gears pq. As the speed 
 of rotation increases, the balls move in the 
 direction of the arrows, compressing the 
 spring s and depressing the stem S of the 
 valve Fby means of the collars. As the 
 valve moves downward, the holes a and g 
 are gradually covered by the wall of the 
 passage, contracting the opening from the 
 gas passage G and the air passage A into 
 the chamber X, and preventing the mixture 
 from flowing in as great a quantity as before, 
 into the inlet port /. 
 
 An example of the shaft governor is 
 shown in Fig. 21, in connection with a de- 
 vice for opening the gas valve only when 
 the engine is below speed. The balls bb are 
 on the end of the short arms // pivoted at pp. 
 As the crankshaft C revolves, the balls tend 
 to swing in the direction indicated by the 
 arrows, but they are withheld by the springs 
 s. As the balls swing about the pivots />/>, 
 the opposite ends of the arms // move toward 
 X and carry with them the collar c. A 
 long lever m with a fulcrum pivot at P is 
 
 92 
 
93 
 
carried with the collar and the long end 
 pushes the point out of line with the stem 
 v of the gas valve. The point x is attached 
 to the air valve mechanism so that it rocks 
 backwards and forwards at every movement 
 of the air valve. When the speed is too 
 high the governor causes the point x to 
 miss the valve-stem and no gas enters the 
 cylinder. 
 
 In Fig. 22 is illustrated one form of the 
 pendulum or inertia governor arranged to 
 hold the exhaust valve open so long as the 
 engine is above speed. The valve stem is 
 operated from the camshaft by means of 
 the slide M. On the slide is carried the 
 pendulum P which swings about the pivot 
 J>. If, upon the return of the slide, the 
 speed is higher than that for which the 
 governor is set, the pendulum lags behind 
 and the end of the long arm a of the bell- 
 crank to which the pendulum is attached, 
 strikes the pin c and throws it in the path 
 of the block B, holding the valve open. 
 Upon the following stroke of the slide, the 
 valve-stem >S receives a thrust sufficiently 
 long to allow the pin c to drop out of the 
 way of B unless the arm a is still in the 
 way. If the arm allows the pin to drop, the 
 valve closes and the engine takes up its 
 cycle once more. The speed of the engine 
 may be varied by a simple adjustment of 
 
 94 
 
b 
 
 s 
 
 95 
 
the pendulum ball P. If it is desired to 
 increase the speed of the engine, the set 
 screw n is loosened and the ball P is raised. 
 L/owering the pendulum makes the gov- 
 erner act at a lesser speed. 
 
 This form of governor is also much used 
 to control the gas valve. The long arm a 
 of the bell-crank is pointed and it is used 
 to give the necessary thrust to open the 
 valve. In case the speed rises above a cer- 
 tain amount the arm a swings aside and 
 misses the gas valve stem. 
 
 96 
 
CHAPTER XII. 
 
 STARTERS. 
 
 Engines larger than eight or ten horse- 
 power are difficult to start by turning the 
 flywheel by hand, and, in order to lessen 
 the amount of labor involved, larger en- 
 gines than the above are usually supplied 
 with some device by means of which an 
 impulse may be given to the piston when 
 the engine is at rest, that will be strong 
 enough to propel the engine for three or 
 more revolutions and until it can take up 
 its cycle and receive an impulse in the 
 regular way. The methods in use for this 
 purpose are so numerous that but a few 
 examples may be illustrated in a volume of 
 this nature. 
 
 The first method to suggest itself to an 
 engineer would obviously be to apply pres- 
 sure to the engine for one or more strokes- 
 from an exterior source, as from a steam 
 boiler or from a tank of compressed air. In 
 fact, the compressed air starter is a most 
 
 97 
 
convenient form. It is very simple and 
 -consists of a small air pump and a storage 
 lank for the air. A pipe connects the tank 
 to the cylinder of the engine, and this pipe 
 is supplied with a two-way plug-valve. The 
 lank is filled with air, at a pressure of forty 
 pounds or over^when the engine is running, 
 the pump being operated by means of a 
 belt from the line shaft or other convenient 
 point. When it is desired to start the en- 
 gine the flywheel is turned until the cam- 
 shaft is in the proper position for the 
 exhaust stroke, and until the crank-pin is 
 just above the back-center. The air-valve 
 is then opened wide, and closed again as 
 soon as the piston nears the end of its 
 stroke. If the impulse is not strong enough 
 to give the engine a sufficient start it 
 should be repeated at the next revolution 
 l)ut one. Two impulses with the air are 
 usually more than enough for the purpose. 
 After the engine is under way, the fuel 
 should be turned 011 as directed in the 
 chapter on Starting. If the engine has 
 more than one cylinder, one cylinder may 
 be used to start while the remaining cylin- 
 ders are taking up the cycle. Occasionally, 
 the engine is fitted with a special valve 
 mechanism, for the purpose of starting with 
 compressed air, so arranged that an impulse 
 is given to the piston by the air at every 
 
 9 s 
 
Fig. 23. 
 
 99 
 
revolution until the speed is sufficient to 
 lake up the cycle. 
 
 A class of starters that is very much in 
 use on engines of fifty horsepower and 
 l>elow, is simply a means of igniting a 
 charge that has been drawn into the engine 
 by turning it over by hand. For instance, 
 a certain manufacturer equipped his engines 
 with what is called a match igniter. This 
 igniter is shown in section in Fig. 23. The 
 igniter consists of the casting B which is 
 screwed into an opening into the valve-box. 
 It contains a plunger consisting of a tapered 
 and roughened head A, a stem d and a cap 
 C. The plunger is held at the top of its 
 stroke by means of the spring S. A small 
 pet cock s is screwed into the side of B, 
 through which is inserted a parlor-match m, 
 the plug h is then turned so as to break the 
 match-stick and hold it in place. When 
 the engine is under way the cock s is opened 
 and the burnt match expelled by the next 
 explosion within the engine. 
 
 To start the engine, it is turned over until 
 the igniter snaps, and a charge of air is 
 drawn in by turning the flywheel. At the 
 same time, a small quantity of gasoline 
 the amount depending upon the size of the 
 engine is drawn in with the air. The en- 
 gine is now turned over until the piston is 
 at nearly the end of the stroke ; the engine 
 
is then reversed compressing fh^ ciii.r^e 
 by a quick backward turn of the flywheel, 
 the cap C of the igniter is struck with the 
 hand lighting the match m and firing the 
 charge. The explosion is usually of suffi- 
 cient force to turn the engine until it can 
 take up its cycle. 
 
 In some engines, the use of the match 
 igniter is avoided by means of a device 
 which operates the electric-igniter at the 
 proper moment. When the jump-spark is 
 employed, a switch which will close the 
 primary circuit, is all that is necessary. In j 
 other engines the flywheel is turned until 
 the camshaft is at the proper position for 
 the beginning of the suction stroke, and 
 the crank-pin is on the inner center. A 
 charge of fuel and air is then pumped into 
 the cylinder by hand. The pressure within 
 the cylinder can be determined by the force 
 necessary to work the pump or by setting 
 the engine a little past the center and hold- 
 ing the flywheel, noting when it begins to 
 pull. When the required pressure is ob- 
 tained, the flywheel should be turned until 
 the pin is about 10 past the center and the 
 charge fired by means of a match igniter or 
 equivalent device. 
 
 In large engines, where the horsepower 
 is 100 h. p. or above, a small gas engine, 
 which may be easily started bv hand, is 
 
. employed to' Inrn t#e large engine over 
 until it takes up its cycle, and the starting 
 engine is then uncoupled automatically. 
 Sometimes the valve mechanism of the en- 
 gine is so arranged that, after the engine is 
 uncoupled from the line shaft and before it 
 is stopped, it is employed to charge a pres- 
 sure tank by permitting a portion of the 
 expanding charge to pass into the tank. 
 This is accomplished by opening communi- 
 cation with the tank after the piston has 
 made a portion of its expansion stroke, the 
 first portion of the stroke being used to 
 impart motion to the engine. 
 
CHAPTER XIII. 
 
 ENGINES FOR AUTOMOBILES. 
 
 The requirements of an automobile en- 
 gine are lightness, compactness, minimum 
 vibration, wide range of speed under con- 
 trol of the operator, and simplicity. Econ- 
 omy of fuel consumption is a secondary 
 consideration. The fewer the cams, levers, 
 etc., on an automobile engine, the less liable 
 will it be to get out of order. It was for- 
 merly supposed by the gas-engine builder 
 that a gas engine must run at a constant 
 speed, and all changes of speed made by 
 means of gears. Recent experiments have 
 exploded this theory and successful engines 
 are now on the market which will run at 
 speeds varying from 100 to 1000 r. p. m. for 
 the same engine. At least one manufacturer 
 claims that his engine may be run at speeds 
 ranging from 100 to 2000 r. p. m. Two- 
 methods are employed for governing the 
 speed of the engine. One is by throttling 
 the charge, and the other by changing the 
 
 103- 
 
lead of the spark. Hither of these methods 
 gives an impulse at each cycle. Bngines 
 operating on the hit-and-miss principle, are 
 useless for motor vehicles. 
 
 For single-seated carriages, an engine 
 capable of giving at least four horsepower 
 at between 500 and 600 r. p. m. should be 
 employed. If the carriage is likely to be 
 called upon for heavy hill-climbing or rac- 
 ing speeds the horsepower should be in- 
 creased to six. For motor bicycles one 
 liorsepower is usually sufficient, while for 
 tricycles two horsepower is that generally 
 employed. Single-cylinder engines will not 
 run in a horizontal position without caus- 
 ing an annoying amount of vibration to be 
 transmitted to the vehicle. If it is desired 
 to use a single-cylinder engine it should be 
 placed with the cylinder vertical and the 
 engine very carefully balanced. Two-cylin- 
 der engines with the cylinders placed end 
 to end, each connecting-rod being attached 
 to a separate crank-pin and the crank-pins 
 placed 180 apart, will, if all parts are care- 
 fully made of the same weight, run with 
 , very little vibration. The reciprocating and 
 rotating parts of the two engines balance 
 each other. Two cylinders with their axes 
 parallel and the open ends in the same 
 direction, work very well when the cranks 
 are set at 180, but still better results in 
 
 104 
 
the matter of balancing are obtained by 
 the use of three or four cylinders with the 
 cranks equally spaced about the crank- 
 circle. 
 
 Among the automobile builders, the jump- 
 spark is finding favor, as it may be better 
 controlled at the high rotative speeds at 
 which these engines run. The change of 
 lead for the spark may be obtained by rotat- 
 ing the cam or switch, as the case may be, 
 around the camshaft. Governors for auto- 
 mobile engines are very well in theory, to 
 prevent the engine from speeding up when 
 an obstruction throws one of the wheels off 
 the ground, but there is no governor w r ithin 
 the knowledge of the writer that will act 
 within a time sufficiently short for the pur- 
 pose. The speed of the engine should 
 always be at the control of the operator. If 
 the engine speed is under control, there 
 will be but two changes of speed required, 
 one for levels and easy grades and the other 
 for hill-climbing. The reversing gear may 
 be connected to the hill-climber as a high 
 speed is undesirable for going backward. 
 
 For cooling the cylinders, both a closed 
 circulating water system is employed, and 
 also ribs radiating from the cylinder-walls. 
 The latter may not be used successfully on 
 cylinders over 3^ to 4 inches diameter. 
 For an engine employing a water-jacket 
 
 105 
 
there should be some method of cooling 
 the water, otherwise the amount of water 
 which it is necessary to carry becomes 
 excessive. In France, where the gasoline 
 automobile is in extensive use, a coil of 
 pipe with collars to increase the radiating 
 surface of the pipe is considerably employed. 
 These collars or disks are stamped from 
 sheet metal and punched with a star-shaped 
 hole in the center and then forced over the 
 tube, while the tube is straight. Afterward 
 the tube is coiled on a comparatively small 
 radius. This coil is made a part of the 
 circulating system and answers its purpose 
 very effectively. The author would suggest 
 that if means were taken to guide air 
 through these coils by means of a curved 
 shield under the carriage it would increase 
 the cooling efficiency of the coil. 
 
 The gasoline and the water-tanks should 
 each have some means by which the quan- 
 tity of the liquid contained in them could 
 be determined at any time without it being 
 necessary for the operator to leave his seat. 
 All parts of the mechanism should be com- 
 pletely enclosed to protect them from dust. 
 For this reason an enclosed crank-chamber 
 is a desirable feature. Lubrication of every 
 part should be strictly automatic, so that 
 when the carriage has been given the 
 proper attention at the outset of a trip it 
 
 106 
 
will need no further attention for a reason- 
 able time at least. The fuel feed should be 
 so regulated that 110 odor of consequence 
 is noticeable at the exhaust opening. The 
 fuel should be under control in order that 
 it may shut off when going down grade, or 
 when stopping the engine. The exhaust- 
 muffler should be a good one, as excessive 
 noise is an objectionable feature. It is nec- 
 essary to sacrifice a little power to get good 
 results with the muffler, but, as already 
 noted, the fuel economy is a secondary 
 consideration. 
 
 107 
 
CHAPTER XIV. 
 
 GAS-KNGINE DIAGRAMS. 
 
 It is quite a general custom, among the 
 manufacturers of gas engines, to base the 
 rated horsepower of an engine upon its per- 
 formance with natural gas of an average 
 quality. If, therefore, a diagram may be 
 laid out which will show the conditions 
 within the engine cylinder during the cycle, 
 when working under average conditions, it 
 will prove of valuable assistance to the 
 designer. In order that the reader may 
 know what to expect, when about to con- 
 sider a departure from the practice of the 
 present builders w r ith reference to compres- 
 sion, and also that he may have an ideal dia- 
 gram with which to compare those he may 
 obtain from the engine after it is built, the 
 author will show just how such a diagram 
 may be built up by the aid of formulas. 
 
 An ideal diagram for an engine working 
 with natural gas as a fuel, is shown in Fig. 
 24. Before laying out the diagram it is 
 
 108 
 
necessary to decide upon, either the com- 
 pression pressure desired, or upon the ratio 
 of the volume of the compression space to 
 that displaced by the piston during the 
 stroke. For the diagram in the figure, the 
 ratio has been taken as 30 percent. The 
 total volume of the cylinder, when the pis- 
 ton is at the end of its outward stroke, is 
 therefore i -f- .3 = 1.3 of the piston displace- 
 ment. As it is much more convenient to 
 consider the total cylinder volume as unity 
 for the purpose of making the calculations, 
 it is necessary to find what proportion of the 
 total cylinder volume is included in the 
 compression space, or to divide .3 by 1.3, 
 giving .2308 as this ratio. In calculating 
 the pressures at various points upon the 
 curves, the following formulas should be 
 used, because they represent the average 
 behavior of the gases shown by actual 
 indicator diagrams taken from engines in 
 operation. For the compression curve 
 
 PV-*=K (i) 
 
 Wherein P= the pressure above a vacu- 
 um or absolute pressure ; 
 
 V= the volume of the gases at 
 the time they are at the pressure P; 
 
 K = a number or constant de- 
 pending upon the conditions, but which 
 is the same for all parts of the same 
 curve. 
 
When the volume of the cylinder is con- 
 sidered as unity, A" becomes the absolute 
 pressure of the atmosphere, usually taken 
 as 14.7. When natural gas is employed at 
 the proportion to air which gives the best 
 effect, the pressure of the gases after explo- 
 sion is four times the pressure after com- 
 pression, both these pressures being those 
 above the atmosphere. 
 
 The formula for the expansion curve is 
 
 />F'-35= C (2) 
 
 Wherein P and V have the same signifi- 
 cance as in formula (i) and C is a constant 
 depending upon the maximum pressure. 
 
 These equations may also be written as 
 follows : 
 
 Py*-3=PV*.3 t />^i. 35=J pK.3S > 
 
 a form which shows the exact relation be- 
 tween any two points on the curve. 
 
 In order that the reader may better see 
 how to apply the above formulas, the com- 
 putation of the diagram in Fig. 24 will be 
 given. Taking first the computation of the 
 pressure at the end of the compression 
 stroke, and applying formula (i) 
 
 />K'.3 = ^=i 4 . 7 , and P=m = 
 
 In order to find the denominator of this 
 fraction, it is necessary to multiply the true 
 
logarithm of the number by 1.3. The log- 
 arithm of .2308 as found in a table of log- 
 arithms (the tabular logarithm) is 1.363236, 
 and since the logarithm has a negative 
 characteristic (number to left of decimal 
 point), the true logarithm must be found 
 by adding the mantissa (number to right of 
 decimal point) to the characteristic as 
 follows : 
 
 i. oooooo 
 363236 
 .636764 
 
 1910292 
 636764 
 
 ^.8277932 
 
 1.172207 (subtracting from i and add- 
 ing T to get the tabular log) . 
 
 Log 14.7=1.167317, and subtracting the 
 log of (.23O8) 1 - 3 the resulting log is that of 
 the compression pressure at the end of the 
 stroke. 
 
 167317 
 
 1.172207 
 
 1.995110 = log of 98.88. 98.88 Ib. is 
 the compression pressure in Ib. per sq. in. 
 above a vacuum. For practical purposes, 
 three figures will be sufficient and 98.9 may 
 be taken as the pressure. The pressure 
 above the atmosphere would be 98.9 14.7 
 --= 84.2 Ib. per sq. in. To get the maximum 
 
pressure, this amount should be multiplied 
 by 4, giving 84.2 X 4^=33 6 - 8 lb -> and 33 6 - 8 -f 
 14.7 351.5 lb. absolute pressure. 
 
 In order that the proper shape of the 
 curve may be very closely approximated, it is 
 best to compute the pressures at three points 
 between the ends. The points for which 
 the calculations in the figure were made 
 are those when the volumes are .35, .5 and 
 .75, and in case of any uncertainty a point 
 should be taken midway between .35 and 
 the higher end of the curve. The pressures 
 corresponding to the points given, are 57.6, 
 36.2 and 21.4 respectively. 
 
 The pressures for the expansion curve 
 are found in the same manner as for the 
 compression curve, but by means of formula 
 (2). Before this formula is applied, how- 
 ever, it is necessary to find the value of 
 the constant C, which is the pressure at the 
 end of the stroke when the volume is equal 
 to i. Hence PI' 1 ** C becomes 351.5 X 
 
 (.2 3 o8) I -35 = C. 
 
 Log (,23o8) I -35 == 1.140368, Log 351.5 = 
 2.545925. Adding these logs gives, for the 
 sum, the log of the constant C, thus : 
 
 1.140368 
 
 2.545925 
 
 1.686293 = lo 4 8 -5 6 - 4 8 -5 6 lb s. is the 
 terminal pressure of the gases in the cylin- 
 der, should release take place at the end of 
 
the stroke. Hence the equation of the 
 expansion curve is PV* *& = 48.56. 
 
 The intermediate pressures for the rer 
 mainder of the expansion curve are found 
 by subtracting the logs of .35, .5 and .75 
 raised to the 1.35 power, from the log of 
 48.56. They are 200.4, I2 3-8 an d 71.6 respec- 
 tively. After these points are located, the> 
 diagram is constructed by drawing the 
 curves through them as shown in the fig- 
 ure. The length of the diagram is 3^'' 
 from the line D C to , and the scale of the 
 spring represented is 160 Ib. Hence unit 
 volume is represented by a length of 3% // , 
 and a height of one inch on the diagram 
 represents a pressure of 160 Ibs. per sq. in. 
 
 In order to make the diagram complete, 
 it is necessary to add the two small curves 
 .at i and r e. The curve at i is that due to 
 the lead of the ignition which causes an in- 
 crease of the rate at which the pressure is 
 rising. It can be drawn but approximately, 
 as it varies in size for any change in the 
 piston speed. Its effect upon the area of 
 the diagram is too small to be of conse- 
 quence, and the only value it has, is to serve 
 as a memorandum when using the diagram 
 for the purpose of comparison with those 
 actually taken from the engine. The curve 
 r c is that produced by the release taking 
 place before the end of the stroke is reached. 
 
 114 
 
The point of release r should be such as to 
 bring the point e where the expansion line 
 meets the atmospheric line A B at the end 
 of the stroke. To draw this curve as it is 
 shown in the figure, erect the vertical line 
 j? r at a distance from Xm equal to .9 time 
 the length of the diagram, which, in the 
 figure, is .9 X -77 -693 time the unit length. 
 Through r and c describe a circular arc, 
 which shall be tangent to the expansion 
 line at r. Joining the points i and m with 
 a straight line completes the diagram. 
 
 The diagram having been drawn, the de- 
 signer may find the M. E. P. by means of 
 planimeter as explained in the chapter on 
 Testing. From the M. E. P. obtained from 
 this diagram, he may calculate the horse- 
 power of an engine of any size which it is 
 proposed to build, or he may determine the 
 dimensions of the engine. The design of 
 the valve motions may, to a certain extent, 
 be founded upon the diagram, as it shows 
 the proper time for opening and closing the 
 valves. It should be the aim of the designer 
 to build an engine that will give as nearly 
 as possible, such a diagram as that shown 
 in the figure, for only with a diagram of this 
 shape are the best results obtained. 
 
 A few diagrams will now be shown which 
 have been made by an engine when not 
 working under the conditions necessary for 
 
producing a diagram similar to that in Fig. 
 24. In Fig. 25 are shown diagrams taken 
 from various engines while in actual opera- 
 tion and they illustrate just what occurs 
 under several conditions. At (A) is shown 
 a diagram taken from an engine which is 
 operating with everything in good working 
 order with the exception of an exhaust re- 
 lease which is a trifle late, indicated by the 
 expansion line not reaching the atmpspheric 
 line X Y until the piston has returned to 
 d. The point of release is shown by the 
 sudden change in the curvature of the ex- 
 pansion line at , the point of ignition by 
 the sudden change of curvature in the com- 
 pression curve at i. 
 
 On either side of the atmospheric line is 
 a curve which is exaggerated in the draw- 
 ing in order that it may be distinct. The 
 upper curve is that produced by pressure 
 within the engine cylinder on the exhaust 
 stroke, and is due to an unnecessarily con- 
 tracted exhaust passage, or to obstructions 
 that have accumulated in the exhaust-pipe. 
 The lower curve is caused by the pressure 
 within the cylinder falling below that of the 
 atmosphere, forming a partial vacuum be- 
 cause of an obstructed inlet passage. Ordi- 
 narily, these curves are too small to be of 
 any moment, but in case they are a quite 
 distinct departure from the atmospheric 
 
 117 
 
line, they show that an unnecessary amount 
 of work is being done by the piston in 
 forcing the gases through the passage, and 
 steps should be taken to remedy the defect. 
 A condition of this kind is spoken of as 
 wire-drawing. Diagram (B) is that produced 
 when the ignition of the charge is late. In 
 this case ignition takes place at i after the 
 crank has passed the center. The loss in 
 area of the diagram is quite noticeable when 
 comparing (B) with (A). 
 
 The reader should learn to distinguish 
 between a diagram produced by late igni- 
 tion and that produced by a weak or a 
 throttled mixture. In (B) the curve indi- 
 cating rise of pressure immediately after 
 ignition, is concave, while in (D) and (E), 
 which are diagrams produced by a w r eak 
 mixture, this curve is either a straight line 
 or is convex. (G) is a diagram in which the 
 ignition is very tardy, and the area lost be- 
 cause of late ignition is shown by the dotted 
 lines. Premature ignition is shown by (C). 
 
 , In this diagram the ignition is at / and the 
 loss of area is illustrated by the proper 
 
 ' diagram being shown in dotted lines.* Dia- 
 gram (F) is an example of the effect of late 
 release together .with obstructed exhaust 
 passages. 
 
 When an engine is operating on fuel 
 which ignites at a low temperature, as is 
 
 118 
 
the case with gasoline and acetylene, the 
 propagation of the flame throughout the 
 mixture is very rapid, causing an explosion 
 which is almost instantaneous. An example 
 of the sort of diagram usually obtained 
 with these fuels is shown in Fig. 26. The 
 sudden blow given to the piston of the 
 indicator, sets the spring in vibration and 
 produces the wavy line which appears at 
 the point immediately following maximum 
 pressure. This effect has been attributed 
 to various causes, such as a rapid succession 
 of explosions, and these in turn have been 
 said to be caused by an uneven distribution 
 of the fuel within the air (a stratified 
 charge). The author believes that very few 
 of these curves are of such a nature as to 
 justify such a reasoning. They are all of 
 the nature of a sine curve, the waves grad- 
 vially lessening in height as the piston 
 proceeds on its stroke. In using these 
 fuels, it is best to make the lead of the 
 igniter somewhat less than when using 
 natural gas or manufactured gas. By lead is 
 meant the time or the distance before the 
 end of the stroke, that ignition takes place. 
 
CHAPTER XV. 
 
 GAS-ENGINp; DIMENSIONS. 
 
 The power of any engine is dependent 
 upon four factors, the average or mean 
 effective pressure upon the piston during 
 the stroke, the area of the piston upon 
 which this pressure is exerted, the length 
 of the stroke, and the number of times per 
 minute the pressure is exerted. The power 
 of an engine computed from the above fac- 
 tors is known as the indicated horsepower 
 (I. H. P.). The power delivered at the pul- 
 ley or obtained from the engine, and which 
 is available for power purposes, is called the 
 delivered horsepower (D. H.P.) or the brake 
 horsepower (B. H. P.) and by some writers 
 the effective horsepower (E. H. P.). The 
 use of the latter abbreviation is, however, 
 likely to cause confusion as the same abbre- 
 viation is employed for electrical horse- 
 power. The tef\n brake horsepower is de- 
 rived from the manner of testing the output 
 
of the engine, which is usually with some 
 form of brake. The D. H. P. is the I. H. P. 
 minus the power absorbed in the friction 
 of the engine, the latter being called the 
 friction load. The ratio of the D. H. P. to 
 the I. H. P. is called the mechanical effi- 
 ciency of the engine, sometimes abbreviated 
 
 to M. E., and M. B. = D ' H ' ^' , this ratio 
 
 being usually expressed in percent. Thus, 
 if the I. H. P. of an engine is 10 H. P. and 
 the D. H. P. is 8 H. P., the M. E. = T 8 o = 80 
 percent, and the friction load = 10 8 = 2 
 horsepower. 
 
 The mean effective pressure (M. E. P.) in 
 a gas-engine cylinder varies with the fuel, 
 the pressure after compression, the propor- 
 tion of the mixture and the time of igni- 
 tion, and in a minor way on several other 
 conditions which are not of sufficient im- 
 portance to consider at present. If the 
 mixture contains the most effective pro- 
 portion of gas and air, and the ignition is 
 properly timed, as it should be, it leaves 
 the matter of compression and quality of 
 fuel as the two important points to be con- 
 sidered, with reference to the M. E. P. The 
 highest mean effective pressures are those 
 obtained with natural gas and gasoline, 
 then come the illuminating gases in the 
 order of their light-giving values water- 
 
gas and semi-water-gas the latter being 
 usually known as producer-gas. For the 
 compression pressure usually employed, the 
 M. E. P.s range between 45 Ib. per sq. in. 
 and 80 Ib. per sq. in., with the average not 
 far from 65 Ib. per sq. in. for an average 
 quality of natural gas. For gasoline the 
 M. H. P. may safely be taken at 70 Ib. per sq. 
 in. The author has found the following 
 formulas are very well borne out in practice 
 for the best performance of the average 
 gas engine : 
 
 Let D = the diameter of the cylinder in 
 inches ; 
 
 L = the length of the stroke in inches ; 
 
 R = the number of revolutions per min- 
 ute ; 
 
 Then for a four-cycle engine 
 
 19,000 
 
 For a two-cycle engine 
 ' 
 
 IO,OOO 
 
 For engines using gasoline these denom- 
 inators should be reduced to 18,000 and 
 9,500 respectively. These formulas may be 
 used for determining the dimensions of 
 any engine that is being designed, if the 
 performance of any engine of the same 
 kind and on the same quality of fuel is 
 already known. The denominator of the 
 
fraction then becomes an unknown quan- 
 tity and it may be found as follows : 
 
 Calling the unknown denominator A' 
 
 X = X -^ X ^ / \ 
 
 (D. H. P.) 
 
 Suppose an engine which is a good ex- 
 ample of a series already being built has a 
 cylinder 2O // diameter and a stroke of 3O /X , 
 i. e., a 20 XX X 30 XX engine, and that it runs at 
 120 r. p. m. giving 70 D. H. P., the value of 
 Xis 
 
 v= (20)2 X 30 XI20 _ 
 
 ^- 20,577 -1 
 
 call X 20,600. 
 
 The formula fer these engines is then 
 
 nz v 7 v I? 
 D. H. P. = A ^ A ^ 
 
 20,600 
 
 To find the diameter of the cylinder for 
 any engine to give a required horsepower 
 at a given speed, the ratio of the stroke to 
 the diameter should first be determined. 
 For a four-cycle engine, prominent author- 
 ities agree that the best proportion is to 
 make the stroke ij^ times the cylinder 
 diameter. For a two-cycle engine, practice 
 varies between making the diameter of the 
 cylinder and the stroke the same, to a stroke 
 equal to i^ times the diameter. It is also 
 necessary to decide upon the speed at 
 which the engine shall run. Gas engines 
 built in the United States, are seldom run 
 
at a higher piston speed for horizontal en- 
 gines than 600 feet per minute and for 
 vertical engines 700 feet per minute. The 
 following formulas representing average 
 practice among manufacturers will be found 
 valuable in making the first approximate 
 calculation : 
 
 Let H = the D. H. P. of the engine ; 
 
 Let R = the rev. per min. ; 
 
 Then for a four-cycle engine A* =-^ ' 
 
 " " two-cycle " R = -44. W 
 
 
 
 In order to solve the above two equations 
 it is necessary to use logarithms. Suppose 
 it is 'desired to find the speed of a fifteen- 
 horsepower four-cycle engine. Take a table 
 of logarithms and find first the logarithm 
 of 15, which is 1.176091 ; multiplying by .21 
 the result is .24697911, which is the log of 
 15 to the .21 power. The log of 380 is 
 2.579784; subtracting the log of (i5)- 21 from 
 this 2.579784 
 .246979 
 2.33 2 705 = log 215-1 + 
 
 And the proper speed for this engine 
 would be 215 r. p. m. or thereabout. For a 
 four-cycle engine, formula (6) gives a piston 
 speed of 600 feet per minute at 32.5 horse- 
 
 125 
 
power, and for a two-cycle engine, formula 
 (7) gives a piston speed of 600 feet per min- 
 ute at 71 horsepower. Beyond these powers, 
 the formulas (6) and (7) should not be used 
 but the computations made from the piston 
 speed. At 600 feet piston speed the r. p. m. 
 is found as follows : 
 
 (8) 
 
 JL, 
 
 When the piston speed of the engine is 
 600 feet per minute, much simpler formu- 
 las than (3) and (4) may be used to find the 
 diameter of the cylinder. Using the same 
 value of X as before, 
 
 D = 2.3 ^/ H for a 4-cycle engine ; A' = 
 19,000. (9) 
 
 D = i.67/y/ H for a 2-cycle engine ; X = 
 10,000. ( 10) 
 
 These formulas should not be used ex- 
 cept for a piston of speed of 600 feet per 
 minute. The stroke of the engine can 
 afterwards be determined by its ratio to 
 the diameter, and from that the r. p.m. may 
 be found by means of formula (8). It should 
 be remembered that these equations are 
 applicable as they stand, only for engines 
 with one cylinder. When the engine is to 
 be built with two or more cylinders, the 
 horsepower must be divided by the number 
 of cylinders. Thus, if a three-cylinder en- 
 
 126 
 
glne of 45 horsepower is to be designed, the 
 calculations for cylinder diameter, r. p. m., 
 etc., should be made for a i5-horsepower 
 engine. 
 
 Should the reader desire to calculate the 
 power of a gas engine from a known M. B. 
 P., the following formulas will assist him. 
 When the piston speed is 600 feet per min- 
 ute and the stroke of the piston is i^ times 
 its diameter 
 
 p 
 
 Wherein P = the M. B. P. 
 When the piston speed is 700 feet per 
 minute 
 
 D= 1.55 V 1 - H - p - ( I2 ) 
 
 ~P 
 
 Both of these formulas are for the 4-cycle 
 engine. If it is desired to find the D. H. P., 
 an M. B. of 80% may be safely employed 
 for engines under 25 horsepower. For 
 larger engines having two or more cylin- 
 ders 85% may be used. The reason that a 
 higher efficiency may be obtained from 
 multiple cylinder engines, is that the fly- 
 wheels are much lighter, and the load is 
 better distributed throughout a revolution, 
 reducing the friction of the engine. It is 
 fast becoming the custom to build engines 
 larger than 50 D. H. P. with two or more 
 
 127 
 
cylinders. Although four-cylinder engines 
 have been built and are in use, it is the 
 opinion of many gas-engine experts that 
 no material advantage is gained by increas- 
 ing the number of cylinders beyond three. 
 The cylinder diameter of a gas engine 
 may be made the basis of nearly all other 
 dimensions of the engine and not make 
 them vary but a few percent from what 
 would be given by the best of formulas. 
 Although every dimension of the engine 
 should rightly be discussed in the present 
 chapter, the author will give each part a 
 chapter by itself in order to make them 
 easier of reference. 
 
 128 
 
CHAPTER XVI. 
 
 THE CYLINDER. 
 
 A good example of a gas-engine cylinder 
 is shown in Fig. 27. The dimensions of 
 the various parts have been based upon 
 average practice of gas-engine designers in 
 this country, and, although he will not be 
 able to take up any gas-engine design he 
 chances to come across and find the di- 
 mensions exactly fitting these formulas, he 
 will, by the use of the following equations, 
 be able to produce a design which will be 
 in good proportion. 
 
 For the thickness of the cylinder wall it 
 is necessary to allow for reboring to a cer- 
 tain extent, and also to have sufficient metal 
 for stiffness, and to make a good casting 
 when the cylinder is a small one. The 
 thickness of the wall is therefore made 
 quite a little heavier than is necessary for 
 mere resistance to pressure. The following 
 formula is that which represents average 
 practice. 
 
 I2Q 
 

/=.o9/>; (13) 
 
 Wherein t = the thickness of the cylinder 
 
 wall ; 
 
 D the diameter of the cylinder. 
 The depth of the water-jacket is usually 
 as given by the following formula : 
 
 y=..i/V (M) 
 
 Wherein/ = the depth of the water-jacket. 
 This depth is measured on 
 a radius of the cylinder 
 across the water-jacket. 
 No regular proportion appears to be fol- 
 lowed at all closely for the thickness of the 
 outer wall of the water-jacket. The author 
 has used for engines of his own design a 
 thickness which is half that of the cylinder 
 wall, or .045 D. 
 
 For very small engines these formulas 
 give dimensions which produce walls too 
 thin for the foundryman. In order to get 
 good castings it is well to limit the thick- 
 ness of the cylinder wall to T 5 g- inch, the 
 depth of the water-jacket to y% inch, and the 
 thickness of the jacket wall to % inch. 
 
 In order to find the diameter of the cyl- 
 inder head studs the maximum pressure 
 within the cylinder must be known as well 
 as the number of studs. It is a good plan 
 to limit the distance between the studs to 
 six inches, unless there is a feature in the 
 design of the cylinder or the head that will 
 
prevent such a space being used. An even 
 number of studs is almost invariably em- 
 ployed. The following formula should be 
 used for finding the diameter of the stud : 
 L,et A = the diameter of the cylinder ; 
 z = the diameter of the stud at the 
 
 root of the thread ; 
 S 1 the safe stress in Ib. per sq. in.; 
 p = the maximum pressure in the 
 
 cylinder ; 
 n = the number of studs ; 
 
 Then </= or d = D\JL_. (15) 
 
 sn 
 
 sn 
 
 The flange by which the cylinder is at- 
 tached to the frame, may be either square 
 or circular. It is usually square on vertical 
 engines and circular when the cylinder is 
 horizontal. The sizes of the bolts which 
 are used to fasten the cylinder to the frame 
 may be found by formula (15) making z the 
 diameter of the bolt at the root of the 
 thread and n the number of bolts. The 
 thickness of the cylinder wall between the 
 end of the water-jacket and the flange 
 should be .125 D. The thickness of the 
 flange should be equal to the diameter of 
 the bolt -f- %". On engines smaller than 
 six horsepower, it is customary to make the 
 cylinder and the frame in one casting. The 
 water-jacket should extend, beyond the end 
 of the piston nearest the cylinder head, tc 
 
 132 
 
H : ^^^^^^N^\\^^^^\v^ 
 
 ^\^\\\x s \\x\i i? 
 
 i i a 
 
 JSJSSSE^SXSSSS^B 
 
 g gy 
 
 ^^^ix^^vj 
 
 00 
 c* 
 
 133 
 
a distance equal to about 10% of the stroke. 
 The size of the water inlet and outlet pipes 
 should be .15 times the diameter of the cyl- 
 inder. 
 
 Two methods are in use for making the 
 core for the water-jacket space. In one the 
 core-box consists of two cylinders of 
 wrought iron, placed one within the other 
 and of the proper dimensions to make the 
 space between them equal to the size of the 
 core. The core is then rammed up between 
 the two cylinders and put into the core- 
 oven in the core-box. With this method of 
 making the cores there is no necessity of 
 making draft in the core-box for the metal 
 about the studs. Another method of mak- 
 ing the core is to make one half of the core 
 at a time, using the same core-box for each 
 half, the core being lifted out sideways. 
 With this form of core-box it is necessary 
 to arrange the metal as shown by the dot- 
 ted lines in the figure in order to make a 
 draft on the parts y y. 
 
 The cylinder head, when it contains no 
 valves or other mechanism, is made as 
 shown in Fig. 28. The formulas for the 
 thicknesses of the walls and the depth of 
 the water-jacket are the same as for the 
 cylinder. In fact, it may be said to be an 
 extension of the cylinder. In some engines 
 the end of the cylinder is closed and is 
 
made in the form of a sphere. In others 
 the cylinder is closed but a head is used to 
 cover the end of the cylinder in such a 
 manner that it forms the outer wall of the 
 water-jacket at that point. In many en- 
 gines, the valves are placed in the head 
 while in others, the head contains but one 
 valve or the igniter. 
 
 135 
 
CHAPTER XVII. 
 
 VALVES AND VALVE-BOXES. 
 
 The methods employed for handling the 
 charge and the exhaust was discussed in 
 Chapter X. The proportions of the valve 
 passages, the valves and the valve-boxes 
 will be discussed in the present chapter. 
 The proportions of the passages for both 
 the entering charge and the exhaust should 
 be founded upon the speed at which the 
 gases will be compelled to pass through 
 them. Hence the areas of these passages 
 depend upon both the area of the cylinder 
 and the speed of the piston. Too frequently 
 these areas are made smaller than they 
 should be, with a consequent wire-drawing 
 and loss of power. A careful discussion oi 
 this matter with prominent designers, both 
 in this country and in Europe, shows the 
 concensus of expert opinion to be, that the 
 speed of the gases should be limited to loc 
 feet per second in the inlet, and to 85 fee' 
 
 136 
 
per second in the exhaust passages. The 
 85 feet per second allowance for the exhaust, 
 is made on the assumption that the prod- 
 ucts of combustion are driven from the cyl- 
 inder when at atmospheric pressure, this 
 assumption being made for convenience 
 only. As a matter of fact the pressure of 
 the gases at the moment of release range 
 between 30 and 40 lb., and the lower limit 
 of speed for the gases in the exhaust pas- 
 sages is adopted for this very reason. As 
 the piston speed of gas engines varies con- 
 siderably, even for engines of the same 
 power when built by different manufactur- 
 ers, it should always be taken into consid- 
 eration when proportioning the passages. 
 It should also be remembered that to make 
 the areas of the inlet and the exhaust pipes 
 according to the above, and to then choke 
 the column of gas by a small valve opening 
 or cylinder port, is not very good practice. 
 The formulas given below will give the de- 
 signer a short method of determining the 
 sizes of the passages : 
 
 Let .9 = the speed of the piston in feet per 
 minute ; 
 
 A. = the area of the cylinder ; 
 
 a = the area of the inlet passages ; 
 
 a 1 = the area of the exhaust passages; 
 
 D = the diameter of the cylinder; 
 
 d = the diameter of the inlet passage ; 
 
 137 
 
-p- 
 
 - /i 
 
d l = the diameter of the exhaust pas- 
 
 sage ; 
 
 L the length of the stroke in inches ; 
 R = the r. p. m. of the crankshaft; 
 then 
 
 (16) ora = ARL (i6a) for 
 
 - 
 6,000 36,000 
 
 the inlet. 
 
 l = -(17) or a 1 = ARL (lya) for/ 
 5,100 30,600 
 
 the exhaust. 
 
 for the inlet (i6b). 
 
 d l = . 00572/2 ^ /?/, for the exhaust (lyb) 
 When the piston speed of the engine is at 
 the usual limit for horizontal engines these 
 formulas may be still further simplified to : 
 
 a .1 A (i6c); 
 
 a 1 = .12 A (iyc) ; 
 and for passages of circular cross-section to 
 
 dl = .35 D (i 7 d). 
 
 The designer should use the formula best 
 suited to his work and he will find that, in 
 many cases, he may calculate the dimen- 
 sions by one formula and use another as a 
 check. 
 
 The proportions of the valve are shown 
 in Fig. 29. The author does not insist that 
 these proportions should be followed in 
 every case but they form a very convenient 
 
 139 
 

 140 
 
basis for the design of a valve, especially in 
 those cases where it is hard for the designer 
 to decide what to do, as the ratios suggested 
 below will give a valve of good proportion. 
 The dimensions are based upon the diam- 
 eter of the opening as a unit. They are : 
 
 V= 1.14 d; 
 
 b = .14 d\ 
 
 c--= .07 tf; 
 
 s -= .2 d, for short stems ; 
 
 s -= .23 d, for long stems ; 
 
 r = .25 d, the minimum lift of the valve, 
 to which should be added J^ inch to allow 
 for wear. 
 
 At B is shown the usual method of mak- 
 ing an exhaust valve, the head of the valve 
 being riveted to the stem. This is neces- 
 sary because the head of the exhaust-valve 
 should be made of cast iron, as wrought 
 iron or steel will not stand the abrasive 
 action of the hot gases. 
 
 Three methods of arranging the valves 011 
 the engine are shown in Figs. 30, 31 and 32. 
 Fig. 30 is a cylinder head arranged for both 
 the inlet and the exhaust-valve, and the 
 proportions of the various dimensions to 
 the cylinder diameter are marked upon the 
 different parts. It is always a good practice 
 to water-jacket the exhaust-valve, so that 
 the heat may be carried away from both 
 the bearing for the stem and the valve-seat. 
 
 141 
 
142 
 
In the 
 
 11 the figure, the inlet-valve is also shown 
 water-jacketed. It is not necessary to jacket 
 the inlet-valve, as the incoming air suffices 
 to keep it cool. The jacket is continued 
 about the valve in this case, in order to save 
 iron and to retain a uniformity of construc- 
 tion. 
 
 In Fig. 31 is shown a valve-box designed 
 to be attached to the side of the cylinder 
 and to so place both valves that their stems 
 are parallel and point in the same direction. 
 This box is a style used on both horizontal 
 and vertical engines and is employed where 
 the camshaft is at a right angle to the axis 
 of the cylinder and between the valve-box 
 and the crankshaft. In order that the 
 valves may be removed from the box with- 
 out taking them apart, openings are made 
 in the box at Jt and S and the holes are 
 closed with a cap A. The cap is fitted to 
 the box with a ground joint and is held in 
 place by the clamp B. The proportions of 
 the various parts of the box are shown by 
 formulas on the figure. But one view of 
 the box is shown, a cross-section through 
 the axes of the valves. It is bolted to the 
 cylinder by means of studs passing through 
 the holes j, the studs serving also to hold 
 the cover of the box. The inlet gases enter 
 through a cored passage in the cylinder and 
 the opening /, from whence they pass 
 
 143 
 
144 
 
through the inlet-valve to the cylinder-port 
 P. From the port P the products of com- 
 bustion pass through the exhaust-valve 
 opening to E and through to a cored ex- 
 haust passage in the cylinder. 
 
 Fig. 32 is an illustration of a valve-box so 
 arranged us to place both valves in a box of 
 the smallest possible compass. .The ex- 
 'haust-valve is operated by means of a cam, 
 but the inlet-valve is intended to be ope- 
 rated by the suction of the engine piston. 
 The box is shown in section through the 
 plan. In order to permit of removal of 
 the valves, the seat for the inlet-valve and 
 the bearing for its stem are placed in a 
 separate casting, which is bolted to the box 
 as shown. The opening from the valve- 
 box into the cylinder is shown at B and 
 from the jacket surrounding the exhaust- 
 valve to the jacket of the cylinder at A. 
 The exhaust-valve opening is shown at E 
 and the inlet-valve opening at /. The ex- 
 haust-valve is bolted to the box by means of 
 a flange, while the inlet is screwed into the 
 side of the cover at C. It would be well to 
 put a union into the inlet pipe near the box, 
 in order that the cover may be taken off 
 without difficulty. The dimensions of the 
 the various parts of the box are shown b} 
 equations on the figure, as in Figs. 30 and 31, 
 
 u.s 
 
CHAPTER XVIII. 
 
 THE PISTON, THE COXXECTING-ROD 
 AND THE CRANKSHAFT. 
 
 With few exceptions, all gas engines are 
 fitted with trunk-pistons. The principal 
 reason for the adoption of the trunk-piston 
 is, that if the engine were made double-act- 
 ing, as are most of the steam engines, the 
 hot gases would surround the piston-rod 
 heating it to a temperature that would cause 
 it to cut in the stuffing-box. The trunk 
 piston taking an impulse on the end where 
 there would be no rod were the engine 
 double-acting, gives no trouble from this 
 source. As the other end of the cylinder is 
 not used, there is no necessity for closing it, 
 and by making the piston long enough to 
 act as a guide, there is no need for either a 
 piston-rod or a cross-head. A few engines 
 are manufactured which are double-acting, 
 the trouble from an overheated piston-rod 
 being avoided by providing means for cool- 
 ing the rod. In one of these engines the 
 water-jacket is extended so that it surrounds 
 
 146 
 
ie stuffing-box, while in another, the rod 
 is made hollow and water is circulated 
 through it. 
 
 The present discussion will be confined 
 entireh- to the trunk-piston. For a treat- 
 ment of the piston for the double-acting 
 engine, the reader is referred to works on 
 steam-engine design. An example of the 
 trunk-piston, as usually employed with the 
 gas engine, is shown in Fig. 33. The pro- 
 portions are, with the exception of the 
 pin, based upon the cylinder diameter as a 
 unit. All the necessary equations are placed 
 upon the drawing. For small pistons of S" 
 diameter and under, the ribs R may be 
 omitted, and the piston designed as shown 
 by the dotted line. In some engines there 
 is a supplementary piston-ring added, as 
 shown by the dotted lines at Z. Up to and 
 including pistons \Q" diameter three rings 
 will be found sufficient. For sizes above S", 
 four rings should be used, one of which 
 may be placed as shown at Z. In pistons 
 above \2" diameter four rings should be 
 placed between the pin and the inner end. 
 and a fifth ring added at Z if it is desired to 
 place a ring at this point. The extra ring 
 is of somewhat doubtful utility, so far as 
 the packing ring Z is concerned. It is con- 
 tended by some that it relieves the piston of 
 pressure on the cylinder, but as the piston 
 
 U7 
 
N 
 
 i 
 N 
 
 a 
 
 148 
 
is not in any way supported by the rings, it 
 is difficult to see what foundation there is 
 for such an argument. In using the equa- 
 tions given in Fig. 33, the designer should 
 be careful to observe the limits, on the 
 smaller sizes, that it is necessary to consider 
 for securing good castings. The piston 
 wall should not be less than T \ x/ , and even 
 then the pattern should allow considerable 
 stock to be turned out in the lathe. The 
 difference in the thickness of the rings at 
 the smaller and the larger ends may be less 
 or more than T ^ x/ according to the method 
 of turning them up. A ring which would 
 be of equal strength throughout would 
 taper off to nothing at the smaller end. In 
 the shop when turning piston-rings for a 
 gas engine, some method should be followed 
 whereby the outside of the ring is turned to 
 a perfect circle, the diameter of which shall 
 be exactly the same as the bore of the cylin- 
 der. In order to do this it is necessary to 
 first cut the rings a"nd then to clamp them 
 in a jig which will hold them sprung very 
 nearly together. The ring is then turned 
 to the diameter of the cylinder while held 
 in the jig. This is the secret of securing a 
 tight piston, and one that will successfully 
 withstand the high pressures due to the 
 increase in compression, which is now so 
 extensively coming into use. 
 
 149 
 
"^iiftiz 
 
The diameter p of the piston-pin should 
 be determined by the bearing surface re- 
 quired ; the length of the pin should be r 
 wherever possible, the same as that of the 
 crank-pin. The average pressure which is 
 allowable upon the piston-pin per sq. in. of 
 projected area is 7.50 Ibs. In order to find 
 the diameter of the pin, when the length is 
 known, the designer may make use of the 
 following equation. 
 
 f= ( l8 ) 
 750 Xe 
 
 Wherein p = the diameter of the piston 
 pin ; 
 
 A = the area of the cylinder : 
 
 P = the M. B. P. ; 
 
 e = the length of the piston pin. 
 The connecting-rod of a gas engine is 
 made in various styles, but what is known 
 as the marine type, and illustrated in Fig. 
 34, is that in most general use. This rod is 
 of circular cross-section and is easily ma- 
 chined, as it is nearly all of it turned in the 
 lathe. It is made slightly tapering, the 
 larger end being that nearest the crank-pin. 
 The taper given is dependent to some ex- 
 tent upon the length of the rod, the crank 
 end being from ^^ to ^" larger than the 
 piston end. Thus, for a 24" rod the differ- 
 ence would be ^''^ and on a 60" rod a dif- 
 ference of Y%" , or a difference of }/%" for 
 
?ach foot between centers. The mean di- 
 ameter of the rod, /. ^., the half sum of the 
 diameters of the two ends may be found by 
 means of the formula given below. 
 
 r = .035 \/w; (19) 
 
 Wherein r = the mean diameter of the 
 rod ; 
 
 D = the diameter of the cylinder ; 
 / = the length of the rod be- 
 tween centers in inches ; 
 
 m = the maximum pressure 
 
 within the cylinder in Ib. per sq. in. 
 
 For the convenience of the designer the 
 
 author has deduced the following formulas 
 
 for the mean diameter for engines in which 
 
 the stroke is i% times the diameter of the 
 
 cylinder. When / = 2, L being the length 
 
 of the stroke, 
 
 r== .06 D i/ m (19 a) 
 
 When / 2.5 L, r = .068 1) \ /- ^ (19 b) 
 l=$L, r === .074 D j 1 /"^" (19 c) 
 
 These formulas may be still further sim- 
 plified by extracting the fourth root of m 
 for a range of pressures within ordinary 
 use. Thus, when / = 2/, and m is 240 Ib. 
 per sq. in. r .236 D. 
 
 Call the coefficient of D in this equatioi: 
 /'"and the formula becomes r =* FD. (19 d] 
 
 The values of F for various proportions 
 of / and L and for different values of m an 
 
 152 
 
given in the following table. The designer 
 may take the values nearest to those he 
 expects to use, and from these find the di-. 
 mension of r. 
 
 When 7=2/. When 7=2.5^ When 7=3/, 
 
 ;;/ /v . F=^ F = 
 
 240 .236 .268 .291 
 
 280 .245 .277 .303 
 
 320 .253 .288 .313 
 
 360 .261 .296 .322 
 
 400 .268 .304 .331 
 
 The proportions of the various dimen- 
 sions of the brasses, etc., to sizes of the 
 pins are shown on the figure. 
 
 The crankshaft of a gas engine has to 
 withstand not only the strain due to the 
 transmission of the entire power of the 
 engine, but this strain, at the time it conies 
 upon the shaft, is equal to four times the 
 average power transmitted. This is one 
 reason why the crankshaft of a gas engine 
 must be so much larger than that of a steam 
 engine of the same power. To find the di- 
 ameter of the crankshaft, the diameter of 
 the cylinder and the maximum pressure 
 within the cylinder, is taken as the basis of 
 computation. 
 
 Let 6"= the diameter of the crankshaft ; 
 
 D and m as above ; 
 
 Then for steel ,-.059 D f / ~f^ (20) 
 For wrought iron ,V .064 D i^"^T (20 a) 
 
 
 153 
 
These formulas are lor the average case 
 of L = i% D. When there is much of a 
 departure from this ratio the following for- 
 mula should be used : 
 
 For wrought iron, 
 
 5= .056 ^~^ZJ9 a ~ ( 20 *) 
 For steel, S= .052 f m L D * (20 c) 
 These formulas will give somewhat larger 
 crankshafts than are in use on many gas 
 engines, but it is a matter worthy of note 
 that too many crankshafts are made too 
 small. The diameter of the crankpin is usu- 
 ally made i^ times that of the crankshaft. 
 Practice varies in this respect from making 
 the pin the same diameter as the shaft to 
 1.25 times the shaft. It is a good plan to 
 select the larger rather than the smaller 
 ratio. Mr. Frederick Grover, an English 
 writer, recommends the ratio 1.2 as the 
 lowest limit. It should be remembered that 
 the larger the diameter the shorter the pin. 
 The projected area of the crankpin should 
 be such that the average pressure does not 
 exceed 400 Ib. to the sq. in. From this the 
 following formula is derived : 
 
 /= dJ? (j 
 
 400^7 
 
 Wherein q = the diameter of the pin ; 
 fr= the length of the pin ; 
 A and P as in formula (18). 
 
I 
 o- 
 
 -b + 
 
 155 
 
The length of the crankshaft bearing is 
 usually from 2S to 2.5,5", the smaller ratio 
 2S being that in most general use. Fig. 35 
 shows a good example of a crankshaft with 
 those proportions not already given, marked 
 upon the figure. 
 
 156 
 
CHAPTER XIX. 
 
 THE ENGINE FRAME. 
 
 As with many other parts of the gas en- 
 gine, the frame is built in so many different 
 styles that to give an example of every one 
 would take up more room than is at the 
 disposal of the author in this work. 
 
 A good example of the style of frame in 
 use on a great many horizontal gas engines 
 is shown in Fig. 36, w r ith the proportions of 
 the various parts shown by their relation to 
 the cylinder diameter of the engine. The 
 angle of the parting line of the bearing 
 brasses is taken at 45, in order that the 
 thrust of the piston may not come directly 
 against the stud, but against the frame. 
 The most rational angle for the parting 
 line would be at 90 to the resultant of the 
 average total pressure of the piston and 
 that of the flywheels. This would, however, 
 make the angle a very steep one, and it 
 makes a much neater-looking design to 
 make the angle as shown, while keeping 
 
 157 
 
If 
 
 158 
 
the pressure of the thrust from the piston, 
 on the frame. The cylinders of gas engines 
 are quite frequently cast with projections 
 on the side, by which they are bolted to 
 the frame, as shown in cross-section at Z. 
 It is claimed that the overhanging piston 
 will not get out of shape when the tem- 
 perature rises while the engine is at work. 
 The author must confess that he has been 
 unable to detect any difference in the effect 
 upon the cylinders with an engine built by 
 either method. In some engines the frame 
 is set directly on the foundation, while with 
 others a sub-base is furnished, which is 
 practically a continuation of the frame. It 
 is usual to make the lower part of the frame 
 hollow when there is no base, and to draw 
 the air supply from this space in order to 
 v make the suction a quiet one. When there 
 is a base, the air is drawn from the hollow 
 portion of the base. 
 
 159 
 
CHAPTER XX. 
 
 FLYWHEELS. 
 
 The great proportion of idle strokes to 
 those in which work is actually being done 
 upon the piston makes it imperative that 
 the gas engine be supplied with a very 
 heavy flywheel in order to regulate the 
 speed within reasonable limits. For dif- 
 ferent requirements in speed regulation 
 there will be a difference in the weight of 
 the flywheel. Steadiness of speed is usually 
 spoken of as percent variation, for the rea- 
 son that there is no such thing as absolute 
 uniformity of speed, but a variation between 
 limits that is determined by the efficiency 
 of the governor mechanism and the regu- 
 lating power of the flywheel. Thus, a gas 
 engine that is operating with a speed vari- 
 ation of 2% and at an average speed of 200 
 r. p. m., has a difference between the high- 
 est and the lowest speed of the engine 
 occurring between one impulse stroke and 
 
 1 60 
 
;he next, of 200 X- 2 4 revolutions; and 
 since the average speed of the engine should 
 be 200 r. p. m., the speed should vary be- 
 tween 202 r. p. m. and 198 r. p. m. It is as 
 well to note, at this point in the discussion, 
 a mistake that is occasionally made. This 
 is, to consider the steadiness of speed as 
 the percent of difference of speed between 
 no load and full load. To illustrate : If the 
 engine ran at 220 r. p. m. at no load, and at 
 212 r. p. m. at full load, then the speed va- 
 riation would be considered as 220 212=8 
 r. p. m., and the engine said to regulate 
 within 8-^-216=3.7%" nearly. A little reflec- 
 tion will show that the steadiness of motion 
 is not to be determined by the difference 
 between the speeds at no load and at full 
 load, this matter being one that is depend- 
 ent in a great measure upon the regulating 
 power of the governing mechanism ; or, in 
 other words, upon the efficiency of the gov- 
 ernor. The steadiness of speed between 
 one impulse and the next is dependent 
 entirely upon the power for storing energy 
 that is contained not only in the flywheel 
 of the engine but in the moving parts of 
 the machinery it is driving. Thus, the ar- 
 mature of a dynamo adds somewhat to the 
 power of storing energy, as do the pulleys, 
 etc., of any pieces of machinery being 
 driven. In the operation of electric gener- 
 
 161 
 
ators for incandescent lighting, the regu- 
 lating power of the engine flywheel is quite 
 frequently augmented by the use of an ad- 
 ditional flywheel on the armature shaft, oil 
 a jack-shaft between the engine and the 
 dynamo, or on both the dynamo shaft and 
 the jack-shaft. 
 
 It is obvious that the rational method of 
 calculating the energy storing power re- 
 quired in the gas-engine flywheel is to 
 make a graphical diagram of the operations 
 that take place within the engine cylinder 
 and to transform them into a diagram show- 
 ing the resultant effect of these forces upon 
 the crank-pin. There are two ways in which 
 this may be done. One of these methods 
 considers only the effect of the pressures 
 within the cylinder, while the other and 
 most accurate method brings in the effect 
 of the reciprocating parts of the engine, 
 /. ^., the piston, the connecting-rod and the 
 cross-head when it is employed. Both of 
 these methods require tedious calculations, 
 and the reader is referred to works of greater 
 scope than the present one for description 
 and explanation of these methods. For the 
 case of a gas engine operating under aver- 
 age conditions the following formulas will 
 be found to give good results in practice. 
 They give values that are within a very few 
 percent of those obtained from the actual 
 
 162 
 
diagram of the engine, and show good re- 
 sults in practice : 
 Let W = the weight of the flywheel rim in 
 
 pounds ; 
 
 f= the diameter of the flywheel at the 
 center of gravity of the rim in 
 inches ; 
 
 N= the r. p. m. of the crankshaft; 
 E= the coefficient of unsteadiness per- 
 missible ; 
 
 I. H. P. X 111,600,000,000 
 Then W= f* N *R ( 22 > 
 
 when the engine has an impulse at every 
 fourth stroke. If the I. H. P. is taken as the 
 power of the engine when operating at less 
 than the maximum number of explosions, 
 the value of the figure in the numerator 
 must be increased in proportion. Thus, 
 should the calculations be made for an 
 I. H. P., taken when the engine is getting an 
 impulse only every eighth stroke, the weight 
 found by the above formula must be multi- 
 plied by 2. The value of the coefficient E 
 for the various classes of work is given by 
 competent authorities to be: 
 
 For pumping water and all ordinary 
 duties 05 ; 
 
 For driving machine tools 03 ; 
 
 For driving textile machinery.. .025; 
 
 For driving, dynamos 02 ; 
 
 For driving spinning machinery .01. 
 
 163 
 
164. 
 
If the flywheel on the engine is to be 
 assisted by flywheels on a jack-shaft, or on 
 the armature shaft of a dynamo or other 
 machinery it may be driving, the power 
 storing effect should be divided among the 
 various flywheels. This is done by first 
 deciding what power is stored by the fly- 
 wheels on the engine at the coefficient of 
 steadiness employed, and then finding by 
 means of formula (22) what weight of fly- 
 wheel is required on the jack-shaft to store 
 the remainder, using for f and ^Vthe diam- 
 eter to the center of gravity of the jack- 
 shaft flywheel and the r. p. m. of the jack- 
 shaft. 
 
 The general proportions of a gas-engine 
 flywheel are shown in Fig. 37. Taking the 
 diameter of the crankshaft as a basis of 
 the dimensions of the hub and the spokes, 
 the proportions are as follows : 
 
 h = ic. 
 
 i = y 
 
 d = .8 to I.2C. 
 
 b = .\d to .$d about. This dimension 
 should, however, be calculated from the 
 following formula : 
 
 nNd* 
 
 Wherein B. H. P. = the maximum brake 
 horsepower of the engine ; 
 
 
 ! 
 
 (23) 
 
 165 
 
n = the number of spokes ; 
 
 N "= the r. p. in. of the crank- 
 shaft. 
 
 It appears to be the universal practice to 
 use six spokes for a gas-engine flywheel. 
 The length of the hub should be at least 
 1.5^, and is usually from 1.75 to 2.5 times 
 the diameter of the crankshaft. The di- 
 mensions of the rim must be made to suit 
 the requirements of the engine. The width 
 of the rim will depend upon whether the 
 engine will use flywheel as a pulley or not, 
 and upon the weight required. It should 
 be remembered that the wider the rim the 
 less will be its weight for a given amount 
 of energy storage. The outside diameter 
 is usually from four to five times the stroke 
 of the engine. It is customary to limit the 
 speed of the rim to 6,000 feet per minute, 
 
 or a maximum diameter of D = -3 
 
 N 
 
 wherein D the outside diameter of the 
 wheel and N ^= the r. p. in. 
 
 * Kent's M. K- 1'ocketbook. 
 
 166 
 
CHAPTER XXI. 
 
 BALANCB-WKIGHTS. 
 
 The proper method of balancing an en- 
 gine, and also the correct formula for cal- 
 culating the weight of the balance-weight, 
 is a subject of much discussion among en- 
 gineers. The writer finds it impossible to 
 attempt to give what would be called aver- 
 age practice in this regard, so wide is the 
 difference of opinion. From the conditions 
 under which a gas engine operates, espe- 
 cially engines with a single cylinder, it is not 
 possible to balance an engine perfectly by 
 means of a rotating weight. If the engine 
 be balanced for horizontal vibratory effect 
 it is found that it is too heavily counterbal- 
 anced for vertical movement. It is therefore 
 the custom to attempt a medium between 
 the two. Some builders balance what they 
 consider to be the rotating part of the en- 
 gine, and make no allowance for the recip- 
 rocating parts ; others balance the rotating 
 weights, and add to this one half the recip- 
 
 167 
 
rocating weight. By the first method only 
 the crankpin, the crankarms and that por- 
 tion of the connecting-rod which is consid- 
 ered as rotating, is balanced. This gives 
 rise to two sets of formulas, which, strange 
 to say, give apparently good results in each 
 case. The question now remains, what 
 proportion of the connecting-rod should 
 be considered as having a rotating effect ? 
 This may best be answered by weighing 
 the connecting-rod in the following man- 
 ner : Support the piston end of the rod 011 
 a trestle or other convenient support, and 
 let it rest at a point opposite the center of 
 the bearing on a knife edge ; support the 
 crank end of the rod on a platform or other 
 scales, also by a knife edge, and see that the 
 center line of the rod is horizontal. The 
 weight of the crank end as shown on the 
 scale is that which should be taken for giv- 
 ing rotating effect. If, however, five eighths 
 of the rod be taken as rotating, the result 
 will not be far from wrong. 
 
 Taking the two cases cited above, the 
 following formulas apply : 
 
 Let B = the weight of the balance-weight; 
 M '== the weight of the crankpin -{- 
 the rotating portion of connect- 
 ing-rod ; 
 
 K '= weight of reciprocating parts, 
 including the remaining portion 
 
 168 
 
of the connecting-rod, the pis- 
 ton and the piston-rod and cross- 
 head in engines that employ 
 them ; 
 
 J = weight of both crankarms ; 
 
 m = crank-radius = one half the 
 stroke of the engine ; 
 
 j = the distance to the center of 
 gravity of the crankarm from 
 the center of the crankshaft ; 
 
 q = distance to center of gravity of 
 balance-weight from the center 
 of crankshaft ; 
 
 Then B Mm ' ? for balancing the ro- 
 
 q 
 tating effect alone ; (24) 
 
 (M + *)m + Jj , , . 
 And B = :* - for balancing 
 
 the rotating weight and one half 
 the reciprocating weight. (24 a] 
 The proper place for the balance-weight 
 is considered by a great many designers to 
 be undoubtedly on the crankarms. There 
 are many builders who place a counter- 
 weight on the flywheel near the rim, and 
 some who core out the rim on the side of 
 the flywheel nearest the crankpin. There 
 are two advantages for the latter method; 
 one is that the counterweight may be much 
 lighter, and the other that it is cheaper to 
 make. On the other hand, it is necessary 
 
 169 
 
to make some allowance in an increase of 
 the size of the crankshaft over what would 
 otherwise be necessary, in order that it will 
 withstand the wrenching effect of the coun- 
 terbalance when placed in the flywheel. 
 
 170 
 
CHAPTER XXII. 
 
 FOUNDATIONS. 
 
 Without a good foundation, an engine 
 may be expected to give more or less trouble 
 by vibration, and in time work itself loose 
 from such a foundation as has been pro- 
 vided for it. No engine should be bolted 
 directly to a floor for anything other than a 
 temporary job ; and even when the engine 
 is to be placed upon an upper floor a foun- 
 dation should be built in a hanging frame 
 below the floor. Foundations are usually 
 built of either concrete, stone or brick. On 
 top of the concrete is set a capstone, the 
 best material for which is granite, limestone, 
 bluestone, or any stone of a close-grained 
 structure may be used for the purpose, but 
 the ordinary sandstones will not answer. 
 
 Concrete should be made of good sand 
 and a good quality of cement and broken 
 stone. The stone should pass through a 
 two-inch ring but not go through a one- 
 
.nch ring. Gravel, broken brick and ciii- 
 iers have been used, the latter making a 
 tnuch better concrete than might be sup- 
 posed. The following proportions are those 
 best for concrete : 
 
 Cement I part. 
 
 Sand 2 parts. 
 
 Gravel or stone 5 parts. 
 
 If the cement is a good quality of Port- 
 land, three parts of sand may be used. The 
 concrete should be laid in a crib in layers 
 not over six inches deep, and each layer 
 should be thoroughly tamped before the 
 next is put in. A very good foundation 
 may be made cheaply and quickly in the 
 following manner: Lay a brick wall in 
 cement mortar, making the outside bound- 
 ary that of the finished foundation; then 
 fill in the center with layers of brick or 
 bats, laid flat as in a wall, and loosely. The 
 intermediate spaces should then be filled in 
 with a mixture of one part cement to one 
 part sand. All foundations should be al- 
 lowed three days, at the least, to set before 
 the engine is put in place, and a week is a 
 much better allowance, if there is time to 
 wait that long. It is always best to start 
 the foundation from solid rock or hard pan 
 wherever possible, and it should, at the 
 very least, be started from the ground, i 
 Foundations hung from an upper floor or | 
 
 172 
 
built upon it, should be placed as close to a 
 wall as practicable. When building the 
 foundation, it is necessary to insert in the 
 concrete, gas pipe of an internal diameter 
 equal to twice the outside diameter of the 
 foundation bolts. The nut or threaded 
 plate into which the foundation bolt screws 
 is placed at the bottom of the tube, or the 
 foundation bolt is set in with the tube. 
 After the engine is in place the tubes should 
 be filled with cement. Capstones are not 
 necessary with the smaller engines, and it 
 is often a good plan to lay wooden beams 
 on top of the foundations, and to then put 
 the engine on top of them, so that when 
 the engine frame is bolted down it beds 
 itself into the timber. The timber cap 
 often stops an annoying vibration when it 
 can be overcome in no other way. 
 
 In order to determine the proper dimen- 
 sions of an engine foundation for any en- 
 gine the following formula will be found 
 useful : 
 
 L,et F = the weight of the foundation ; 
 E = the weight of the engine ; 
 R = the r. p. m. ; 
 
 Then F = .21 E 1 /~^~ (25) 
 
 The weight of brick per cu. ft. is 112 Ib, 
 in the wall or foundation. The average 
 weight of concrete is 137 Ib. per cu. ft. It 
 is not customary to make any difference in 
 
 173 
 
174 
 
the foundation design for the various ma- 
 terials, and the author has found that the 
 practice of many designers is to base their 
 dimensions on the weight of concrete. As 
 a concrete foundation is % heavier than a 
 brick foundation of the same size, this is 
 evidently an error. The best way would 
 undoubtedly be to make a separate drawing 
 or list of dimensions for brick, or to at 
 least calculate the dimensions of the foun- 
 dation on the basis of 125 Ib. to the cu. ft., 
 an average of the two weights. 
 
 A very good style of foundation is illus- 
 trated in Fig. 38. It is easily constructed 
 of any material by a fairly good workman. 
 The inclination of wall from the top to the 
 bottom is usually known as the batter, and 
 it is customary to make the batter from 3" 
 to 4 X/ to the foot in height. Instead of 
 building the foundation in tiers, as shown, 
 some designers prefer to make the sides 
 with a gradual slope, as indicated by the 
 dotted lines. The number of foundation 
 bolts varies from four to eight, according 
 to the size of the engine. No less than four 
 bolts are used, and to determine roughly 
 the necessary number of bolts, divide the 
 horsepower of the engine by 6, always using 
 an even number. The sizes of the bolts to 
 use, may be determined approximately as 
 follows : 
 
Let //= the horsepower of the engine ; 
 y = the area of one bolt ; 
 k = the number of bolts ; 
 (26) 
 
 _ 
 
 k 
 
 It should be observed that this formula 
 is entirely an empirical one, and that the 
 designer should consider the strain upon 
 the bolt that is farthest from a line directly 
 under the crankshaft, in cases wherein the 
 shaft is at an unusual distance from the top 
 of the foundation. As a rule it will be 
 found that the above formula gives bolts of 
 ample size for engines of the usual design. 
 
 In case it is necessary to go very deep to 
 find a solid bottom on which to set the 
 foundation, piles may be driven over an 
 area slightly larger than that taken up by 
 the base of the regular foundation, or a 
 crib of timbers laid in. A sub-foundation 
 of timber or piles should be laid, if pos- 
 sible, at a sufficient depth to keep the tim- 
 ber covered with water or very damp earth. 
 
CHAPTER XXIII. 
 
 MISCELLANEOUS FORMULAS. 
 
 The following formulas may prove them- 
 selves useful to those who design or handle 
 gas engines : 
 
 For the diameter of the camshaft : 
 
 Let c = the diameter of the camshaft ; 
 D = the diameter of the cylinder 
 
 in inches ; 
 
 Then c = .057 D -|- .625. 
 For the volume of the muffler ; 
 
 Let M = the volume of the muffler in 
 
 cu. in. ; 
 L = the length of the stroke in 
 
 inches ; 
 
 Then^/= 3.5 />. 
 
 For a closed circulating system of cooling 
 the cylinder the capacity of the tanks is 
 made from 20 to 50 gallons per I. H. P. 
 Thirty gallons is usually considered an 
 ample allowance. The allowance for evap- 
 oration is o.i gallon per D. H. P. per hour. 
 For water flowing through the jacket Mr. 
 
 177 
 
Frederick Grover recommends 4^ gallons 
 per I. H. P. per hour. 
 
 The proper size of marine engine to use 
 for launches up to 50 ft. long may be roughly 
 estimated by means of the following equa- 
 tion : 
 
 Let JB= the length of the boat on the 
 
 load waterline in feet ; 
 H = the horsepower of the engine ; 
 
 Then H=* f 9. 
 
 For the smaller craft, to which so many 
 gasoline engines are applied, the usual rules 
 for the diameter and pitch of a screw pro- 
 peller do not seem to be applicable. The 
 author has derived the following empirical 
 formula for pleasure boats which use en- 
 gines of from i to 12 horsepower. 
 
 Let d = the diameter of the propeller 
 
 in inches ; 
 
 H = the horsepower of the engine ; 
 R = the r. p. in. ; 
 
 Then for a 3-bladed propeller with pitch 
 and diameter equal, 
 
 rf= V22-S2SL2+ 164 
 R 
 
 For a 2-bladed propeller the diameter 
 should be about 8% greater than for the 
 3-bladed propeller. It may be a new propo- 
 sition to many to make the pitch and the 
 diameter equal, as it is the custom of a 
 
great many boat builders to make the pitch 
 1.3 d. One of the most successful launch 
 builders in this country uses the ratio 
 pitch = diameter, and speeds his engines 
 up to correspond. 
 
 179 
 
CHAPTER XXIV. 
 
 TESTING. 
 
 Hvery manufacturer of gas engines has 
 a department known as the testing floor, 
 equipped more or less fully with apparatus 
 for determining, before the engine leaves 
 the factory, if it is working satisfactorily. 
 The primary objects of the test are, first, to 
 find out if the governor is so set as to give 
 the engine its proper speed; second, by 
 means of the indicator, to discover if the 
 igniter is properly timed, whether or not 
 the valves open at the proper points in the 
 cycle, and to see if the compression is of 
 the right amount. The gas-engine indica- 
 tor diagram is of value for the determination 
 of other points in the working of the engine, 
 as has been discussed in Chapter XIV. The 
 third object of the test is to determine if 
 the engine is giving the required amount of 
 horsepower at the pulley. This is known 
 as the delivered or brake horsepower, de- 
 noted bv either the letters D. H. P. or B. H. P. 
 
 180 
 
It is determined by means of a form of ab- 
 sorption dynamometer known as the prony 
 brake. The fourth object of the test is the 
 determination of the fuel consumption of 
 the engine per I. H. P. per hour. 
 
 The necessary apparatus for a gas-engine 
 test, as it is usually carried out on the test- 
 ing floor, is as follows : A good steam-engine 
 indicator, with a piston having an area of 
 X square inch, and, if possible, a pencil 
 movement of extra strength, is the princi- 
 pal requisite for determining the I. H. P. 
 
 There are indicators now to be had that 
 are designed expressly for the gas engine 
 and with the above features. There should 
 also be some good type of reducing motion 
 in order that the movements of the stroke 
 of the piston may be reduced to a stroke of 
 between 2^ x/ and 3^", which is the usual 
 length of the indicator diagram. There 
 should be, if it is possible to obtain it, a test 
 meter reading in single cubic feet in order 
 that the fuel consumption, when the gas 
 engine is used, can be measured with some 
 degree of accuracy. There should also be 
 a prony brake large enough to be attached 
 to a pulley of considerable diameter. The 
 brake should have some means by which its 
 grip upon the wheel may be quickly al- 
 tered, and there should also be a platform 
 fe, and the scale should be accurately 
 181 
 
tested beforehand with a standard weight to 
 determine if its readings are correct. The 
 experimenter should be supplied with a 
 good form of revolution or speed counter, 
 those being the best which have a soft rub- 
 ber tip for placing in the center countersink 
 at the end of the crankshaft. 
 
 For a more refined test than is usual on 
 the testing floor of a factory there is needed 
 a means of measuring the jacket water, 
 thermometers for taking the temperature of 
 the water before passing into the jacket and 
 as it is leaving, a pyrometer for determin- 
 ing the temperature of the exhaust gases, 
 a pressure gauge or a manometer for de- 
 termining the -pressure of the gas, a ther- 
 mometer for determining the temperature of 
 the same, a thermometer to be hung on the 
 wall near the engine to determine the tem- 
 perature of the room, and a barometer for 
 measuring the pressure of the atmosphere 
 at the time the test is made. This appa- 
 ratus is necessary only if making the test 
 for discovery of faults in design, and when 
 it is desired to obtain data upon which to 
 make improvements in the engine. It 
 would, however, be a good plan to always 
 take the pressure of the gas, particularly 
 when natural gas is used and the pressure 
 is more than a few ounces per square inch. 
 Otherwise the experimenter mav be led into 
 
 182 
 
grave errors by striving to calculate the fuel 
 consumption of his engine. No gas engine 
 should ever leave the factory without hav- 
 ing undergone a test for speed and for de- 
 livered horsepower, nor without several 
 indicator diagrams having been taken from 
 the engine. 
 
 A gas engine rigged up for the purpose 
 of making a thorough test is shown in Fig. 
 39. The prony brake is shown applied to 
 the flywheel, and the engine is running 
 over, as shown by the arrow. The brake 
 consists of the strap a with the blocks b 
 bearing upon the periphery of the wheel, 
 and the brake-arm made of the two boards 
 ff. Two cast-iron or wrought-iron angles 
 cc are placed where the band is parted, and 
 through them is put the bolt d> used to 
 tighten the brake by means of the threaded 
 crank e. A platform scale is placed at /, 
 and the thrust of the brake is applied to 
 the scale by the arm f acting through the 
 knife edge g, the iron block h and the 
 wooden stand j. The distance L from the 
 center of the crankshaft to the point where 
 the knife edge rests upon the block h is 
 known as the length of the lever arm. 
 
 The indicator is shown at z, the cord from 
 the indicator passing to the smaller drum 
 of a reducing wheel r, and a cord from the 
 larger wheel being attached to the piston. 
 
 i 
 
184 
 
as shown in the small sketch at the upper 
 right-hand corner of the figure. To attach 
 the cord to the piston a piece of ^ x/ round 
 iron is bent into the shape illustrated and 
 flattened at the end opposite the eye m. 
 Through the flattened portion two holes 
 are drilled, and the rod is fastened to the 
 inside of the piston by means of machine 
 screws or capbolts. 
 
 Water enters the water-jacket through 
 the pipe ze/, controlled by the valve z>, and 
 it leaves the jacket through the pipe w. 
 Thermometers are placed at t and t to de- 
 termine the temperature of the water as it 
 enters and as it leaves the jacket. These 
 thermometers do not set directly in the 
 water but are in small cups filled with oil. 
 
 In leaving the jacket the water is caught 
 in the box B and either weighed or meas- 
 ured as is most convenient. In case it is 
 desired to weigh the water, two receptacles 
 should be provided and one emptied while 
 the other is being filled. Catching the 
 weight "on the fly" is not an accurate meth- 
 od and should be avoided. When using two 
 receptacles, the stream of water should be 
 changed just at the time the signal is given 
 for taking the reading. 
 
 When it is desired to measure the water 
 by volume, the receptacle may be made in 
 the form of a box of the following dimen- 
 
 185 
 
sions, in order to make the measurement 
 easier to read. If the dimensions of the 
 tank are 37^ x 37^- inches, and the meas- 
 uring stick s is marked off in half-inch 
 divisions, each j^-inch in depth will indi- 
 cate 25 Ib. of water. If a smaller tank is 
 desired, it maybe made 26^ x 26$ and each 
 inch in depth will indicate approximately 25 
 Ib. of water. These measurements are made 
 for water at a temperature of 150 F., which 
 is about the average temperature of the 
 water leaving the water-jacket. For very 
 accurate determinations the water should, 
 of course, be weighed. Weighing or meas- 
 uring the water is necessary when making 
 a thorough test, in order to find the amount 
 of heat carried off in the water. 
 
 A meter is shown on the wall at M with 
 the gas bag at G. On the wall near the gas 
 bag, hangs the thermometer T for determin- 
 ing the temperature of the atmosphere and 
 a barometer X for determining the atmos- 
 pheric pressure. The temperature of the 
 exhaust gases, as they leave the engine, is 
 measured by means of the pyrometer p. 
 The temperature of the gas is taken just 
 before it enters the meter, by the thermom- 
 eter t" ', and its pressure by means of the 
 manometer m' . It is also advisable to use a 
 meter for the measurement of the air when 
 it is necessary to compute the ratios of the 
 
 1 86 
 
fuel to the air under the various conditions. 
 It has been the custom in many testing 
 rooms to compute the volume of the air 
 from the difference between the quantity of 
 gas entering the cylinder at each working 
 stroke and the volume of the piston dis- 
 placement. Such a method is an erronous 
 one, as there is usually more or less wire- 
 drawing, and a certain quantity of the prod- 
 ucts of combustion remains from the pre- 
 vious charge, hence the air should be meas- 
 ured by a meter. 
 
 In order that the reader may thoroughly 
 understand the method of making a com- 
 plete test and of working up the data, it will 
 be explained in its entirety. In ordinary 
 testing he may select such portions of the 
 complete test as will suit his purpose, and, 
 before starting the test, a log should be 
 made out as shown on page 188. This log 
 shows at the head of each column just what 
 readings should be taken. The last three 
 columns are for convenience when working 
 up the data after the test, while the balance 
 of the log is for data taken while the test is 
 in progress. 
 
 In making the test, particularly when a 
 large number of readings are to be taken, 
 the engineer in charge should have a suffi- 
 cient number of assistants, in order that the 
 readings may be taken immediately after 
 
 187 
 
S I 
 
 'd 'H 'I 
 
 I81-BAY JOS8 
 
 -qoni 'a 
 
 njoAai .lad 
 spuuod-^oo^ 
 
 spnnod 
 
 spnnod 
 
 u aad 'Aa>[ 
 
 1 88 
 

 the signal. One man should be posted at 
 the brake to keep the pressure upon the 
 scale as nearly as possible at the same point 
 during one run. Another man should have 
 charge of the indicator, and a third should 
 read temperatures, measure the water, and 
 take the readings of the two meters and the 
 barometer. This gives the third man the 
 greatest part of the work, and a fourth man 
 could therefore be used to advantage. The 
 man in charge of the indicator may also 
 take the speed of the engine and count the 
 number of explosions per minute. For 
 taking the speed of the engine, a continuous 
 counter will be found more convenient than 
 an ordinary speed counter, as the speed can 
 be taken in less time. When there are but 
 two observers, readings should be taken at 
 intervals of ten minutes, and the man in 
 charge of the indicator should take all read- 
 ings, as the brake requires constant atten- 
 tion. 
 
 The test should be divided into runs, 
 each run being made at the same horse- 
 power throughout. One run should be 
 made at the full power of the engine, 
 another at the rated horsepower, and a 
 third at 110 load with the brake off. The 
 number of runs, at horsepowers other than 
 the above, will depend upon the size of the 
 engine and the time at the disposal of the 
 
 189 
 
experimenter. The author would suggest 
 making a run at quarter load, half load, and 
 three-quarter load as well as at the loads 
 already noted. At least ten readings should 
 be taken during each run, and fifteen or 
 twenty readings would be much better, if 
 accurate results are desired. 
 
 The test should, if possible, be in charge 
 of a competent engineer. He should be 
 provided with a whistle which should be 
 blown as a preparatory signal thirty seconds 
 before the time of taking the reading. Two 
 blasts of the whistle should be the prepara- 
 tory signal and one blast should be the 
 signal for taking the readings. Promptness 
 should be observed, each man taking his 
 post at the preparatory signal. Under no 
 circumstances should an outsider be allowed 
 to interfere, and, above all, no one but an 
 observer engaged upon the test should be 
 permitted to take a reading. Always enter 
 the data upon the regular log. Keeping 
 notes upon loose slips of paper leads to 
 confusion, and it should be avoided. 
 
 At some convenient time, either before or 
 after the test, the diameter of the piston, 
 the length of the stroke, and the clearance 
 should be carefully measured. In order to 
 measure the clearance, the crank should be 
 placed exactly upon its inner dead center 
 and the valves firmly seated. Carefully 
 
 190 
 
^ weigh a quantity of water and fill the com- 
 pression space so that it is just full and no 
 more, being careful to spill none of the 
 water. Then weigh the remaining water 
 and the difference between the two weights 
 will be the quantity necessary to fill the 
 compression space. Water at 39.1 F. weighs 
 62.5 Ib. per cu. ft. and dividing the weight 
 of the water taken to fill the compression 
 space, by 62.5 gives the volume in cu. ft. If 
 the water is much warmer than 39.1, the 
 weight may be found by the following 
 formula : 
 
 62 ' 5 X 2 = Wt.percu. ft. , 
 
 / + 461, 500 f3i 
 
 * 
 
 500 t -\- 461 
 
 Wherein t = the temperature of the water. 
 
 This formula gives a close approximation 
 to the correct weight. For the usual hy- 
 drant temperatures, dividing by 62.5 gives 
 results sufficiently close for the purpose. 
 
 In making up a report of the test, the 
 form shown on page 192 will be found con- 
 venient. The first line should be filled in 
 with the name of the engine and the 
 manufacturer, the second line with the 
 name of the party by whom the test is 
 made or the engineering firm of which he 
 is the representative, and the third line by 
 the locality at which the test is made, to- 
 gether with the date. 
 
 191 
 
REPORT OK TEST. 
 
 (las Engine 
 
 Test made by 
 
 At... ..19.. 
 
 DIMENSIONS OF ENGINE. 
 
 Diameter of piston In. 
 
 Area of piston Sq. in. 
 
 Length of stroke Ft. 
 
 Piston displacement Cu. ft. 
 
 Clearance Cu. ft. 
 
 Clearance. . . Per cent. 
 
 DATA. 
 
 Duration trial. . Hrs. 
 
 Gas per hour Cu. ft. 
 
 Air per hour .Cu. ft. I 
 
 Ratio, gas to air 
 
 Jacket-water per hour. T/b.j 
 
 Jacket-water temperature, inlet I 
 
 Jacket- water temperature, outlet i 
 
 Jacket-water temperature, range. . F. c j 
 Revolutions per minute . . . .Average. 
 
 Revolutions per hour 
 
 Explosions per minute Average 
 
 Explosions per hour 
 
 Temperature exhaust F. c 
 
 Temperature room F. c 
 
 192 
 
Length of lever arm Ft, 
 
 Brake load, average Lb, 
 
 Gas Weight of cubic foot Lb, 
 
 Air Weight of cubic foot Lb 
 
 Mixture Weight of cubic foot. . .Lb 
 
 Specific heat, gas 
 
 Specific heat, air 
 
 Specific heat, mixture 
 
 Heat value cu. ft. gas B. T. U 
 
 RESULTS. 
 
 Work Ft. Ib. per ruin Average, 
 
 W T ork Ft. Ib. per hour Average 
 
 D. H. P Average 
 
 Indicated M. B. P Average, 
 
 Indicated H. P Average 
 
 Gas per I. H. P Cu. ft 
 
 Gas per D. H. P Cu. ft 
 
 Mech. Eff. D., H. P. -:- I. II. P 
 
 Friction Loss I. H. P. D. H. P 
 
 HEAT PER HOUR. 
 
 Supplied by gas B. T. U 
 
 Absorbed by jacket-water. . . .B. T. U 
 
 Exhausted B. T. U 
 
 Absorbed in work B. T. U 
 
 Radiation B. T. U: 
 
 Thermal efficiency Percent 
 
 B. T. U. per I. H. P ' 
 
A great many of the items in the report 
 need no explanation, and only those that 
 are not likely to be understood by the 
 reader will be explained. The percentage 
 of clearance is found by dividing the vol- 
 ume of the clearance by the piston dis- 
 placement. The ratio of the gas to the air 
 is the quantity of gas used per hour divided 
 by the quantity of air. In engines which 
 take air into the cylinder at each cycle 
 whether gas enters or not, the ratio may be 
 obtained only when the engine runs with- 
 out missing an explosion. The range of 
 temperature for the jacket water is the 
 difference between the temperatures of the 
 outlet and the inlet water. The weight of 
 the gas may be obtained from the gas com- 
 pany or it may be computed from the 
 results of an analysis of the gas by multi- 
 plying the weight of a cubic foot of each 
 constituent by the percent contained in the 
 gas and adding the results. The following 
 table gives the weights per cu. ft. of those 
 gases which occur most frequently and in 
 the greatest quantities in gases used for gas 
 engines, together with their specific heat 
 at constant volume. 
 
 194 
 
L,b. per Spec, 
 Cu. Ft. Heat 
 
 0447 .470 
 
 Olefines 1174 -33 2 
 
 Hydrogen o559 2.406 
 
 Carbon monoxide 0783 .173 
 
 Nitrogen 0783 .173 
 
 Carbon dioxide 1060 .171 
 
 Oxygen 1060 .155 
 
 These weights are for the gases when at 
 an atmospheric pressure of 14.7 Ib. per sq. 
 in. and a temperature of 32 F. The spe- 
 cific heat of a mixture may be found in the 
 same manner as the weight, by multiplying 
 the specific heat for each gas by the percent 
 contained in the fuel and adding the results. 
 The weight of air at 32 F. and at a pres- 
 sure of 14.7 Ib. per sq. in. is .08082 Ib. The 
 specific heat of air at constant volume is 
 .1688. The weight of a cu. ft. of the mix- 
 ture may be found by multiplying the 
 weight of the gas as already found by the 
 percent of gas in the mixture, and then 
 multiplying the weight of air per cu. ft. by 
 the percent in the mixture. The sum of 
 these two results will be the weight of the 
 mixture. The heat value of the gas should 
 in every case be determined at a laboratory. 
 When it is necessary to know the heat value 
 a sample of the gas should be sent to a lab- 
 oratory for examination, taking samples of 
 
 195 
 
the gas at various times and mixing them 
 to obtain an average. The heat values of 
 various fuels will be found in Table I ; but 
 gas is an uncertain quantity in this respect, 
 and the table is not to be relied upon when 
 accurate results are desired. 
 
 Always, when making a gas-engine test, 
 the volumes of the gases, both air and fuel, 
 should be reduced to a standard tempera- 
 ture and atmospheric pressure for the pur- 
 pose of comparison. It has long been the 
 custom of engineers to use as standard/. 
 the temperature of freezing water and tlit 
 average pressure of the atmosphere at the 
 sea level, or 30" of mercury. To reduce 
 the gas from the volume at which the tesc 
 is made to its corresponding volume at 32" 
 and at 30" of mercury in the barometer, 
 the following formula should be used: 
 Let 7^= the temperature at the time of 
 
 the test ; 
 /= the pressure in inches of mer- 
 
 cury ; 
 i 1 -- the volume at this pressure and 
 
 temperature; 
 / the volume at 30" of mercury 
 
 and at 32 P. 
 Then for air : 
 
 30 x (1 -1-461 ) 
 This formula will also give a sufficiently 
 
 10 
 
close approximation when used for gas. 
 The pressure by barometric measure has 
 been used in this formula, as more conven- 
 ient than the ordinary method of comput- 
 ing on the basis of pressure in Ib. per sq. in. 
 In order to reduce the pressure of the gas, 
 when measured in inches of water, to an 
 equivalent pressure in inches of mercury, 
 divide the pressure in inches of water by 
 13.62. If the pressure of the gas is meas- 
 ured in Ib. per sq. in., multiply this pres- 
 sure by 2.033 to reduce to inches of mercury. 
 These ratios are for temperatures of 32 F., 
 and will be found sufficiently accurate for 
 ordinary temperatures without temperature 
 corrections. 
 
 The work in foot pounds per minute is 
 computed from the indicator diagram. It 
 is the continued product of the M. B. P., 
 the area of the cylinder in sq. in., the length 
 of the stroke in feet and the number of 
 explosions per minute. The quantity of 
 heat supplied by the gas per hour is the 
 product of the heat value of the gas per cu. 
 ft. by the number of cu. ft. used per hour. 
 The heat absorbed by the jacket water is 
 the product of the temperature range by 
 the weight of the water supplied. The heat 
 absorbed in work is the number of ft. Ib. 
 per hour divided by the number 778, as 778 
 ft. Ib. is the equivalent of a B. T. U. (British 
 
 197 
 
thermal unit). A British thermal unit is 
 the quantity of heat necessary to raise one 
 pound of water through a temperature of 
 one degree Fahrenheit. The heat carried 
 off by the exhaust gases is found by the 
 formula given below : 
 
 Let S = the specific heat of the mixture ; 
 w = the weight of i cu. ft. of the mix- 
 ture in pounds ; 
 q = the quantity of the mixture in 
 
 cu. ft. exhausted per hour ; 
 
 T = the temperature of the room or 
 
 the average temperature of the 
 
 air and gas entering the engine ; 
 
 T' = temperature of the exhaust as 
 
 measured by the pyrometer ; 
 U = the quantity of heat carried off 
 
 by the exhaust in one hour. 
 Then U Swq ( T T i. (33 ) 
 The volume of the mixture passing 
 through the exhaust, is the sum of the gas 
 and the air used by the engine, and it in- 
 cludes all air passing through the exhaust 
 for any reason. 
 
 The heat otherwise unaccounted for, and 
 determined by subtracting the above three 
 results from the heat supplied by the gas, 
 is usually credited to loss by radiation. To 
 be strictly accurate, the quantity of un- 
 burned fuel passing through the exhaust 
 should be determined, and the heat value 
 
 198 
 
)f this waste fuel subtracted from that sup- 
 plied by the fuel taken into the engine. 
 
 The thermal efficiency is the quotient of 
 ';he heat absorbed in work divided by the 
 heat supplied to the engine in the fuel. It 
 is usually written as a percentage, and it is 
 the only basis upon which two engines 
 should be compared for efficiency. 
 
 The indicated horsepower of a gas engine 
 is determined from the indicator diagram. 
 The area of the diagram should first be 
 found by means of planimeter.* 
 
 The M. E. P. is determined by multiplying 
 the mean ordinate by the scale of the indi- 
 cator spring. In indicators using a special 
 piston for indicating the gas engine, with 
 an area of the spring of X sq. in., the scale 
 of the spring must be multiplied by two for 
 the scale of the diagram, unless it is ex- 
 pressly marked for the smaller piston. 
 
 To find the I. H. P., when the M. E. P. is 
 known, the following formula should be 
 used : 
 
 *For the method of using the planimeter the 
 reader is referred to works upon that subject, as 
 space will not permit of its treatment in this vol- 
 ume. The area of the diagram should then be 
 divided by its length, and the result will be the 
 mean ordinate. 
 
 199 
 
/ H . P. L (34) 
 
 33,OOO 
 
 Wherein P = the M. E. P. ; 
 
 / the length of the stroke in 
 
 feet; 
 a = the area of the piston in 
 
 sq. in. ; 
 n = the number of explosions 
 
 per minute. 
 
 The reader should observe the difference 
 between the value of n in this formula and 
 value of the same letter in the similar for- 
 mula for steam engines. In the formula 
 for the steam engine, n is the symbol for 
 the number of revolutions per minute. 
 
 To find the D. H. P. of the engine, the 
 length of the brakearm L, Fig. 39 the 
 r. p. m. and the pressure exerted upon the 
 scale must be known. The formula for the 
 D. H. P. is : 
 
 D. H. P. = .0001904 pin (35). 
 Wherein p = the pressure upon the scale 
 
 (net) ; 
 
 / = the length of the brakearm ; 
 ;/ = the r. p. in. 
 
 The net pressure upon the scale should 
 be found by subtracting the pressure ex- 
 erted upon the scale by the unbalanced 
 portion of the brakearm and the weight of 
 the block /, Fig. 39, from the total pressure 
 exerted upon the scale. In order to find 
 
the effect of the unbalanced portion of the 
 brakearm, proceed in the following man- 
 ner : When the engine is not running, have 
 a man stand upon the scale platform and 
 balance his weight, i. e., weigh him. Now 
 balance the scale when he has hold of the 
 brakearm and is pulling upward against a 
 slight friction on the brakewheel or pulley, 
 and again when the man is pushing down 
 on the arm. The brakearm should be 
 grasped close by the knife edge and the 
 scale balanced when the brake is in motion. 
 Add together the weight on the scale when 
 the brakearm is being pulled up and the 
 weight when it is being pushed down, and 
 subtract the weight of the man from half this 
 sum. The result will be the pressure due 
 to the unbalanced portion of the arm. Thus, 
 suppose the man to weigh 160 Ib. and that 
 when the arm is being pulled up the scale 
 balances at 180 Ib., while when the arm is 
 being pushed down, the scale balances at 
 170 Ib., the effect of the arm would be : 
 
 '7-'- l8o _i6o = i 5 lb. 
 
 2 
 
 When making a brake test the man in 
 charge of the brake should keep constant 
 watch of the scale beam, with his hand 
 always on the lever e, Fig. 39. Owing to 
 the wide fluctuations in pressure upon the 
 piston of a gas engine, especially in a hit- 
 
 
and-miss engine, this is no easy task, and a 
 good man should be selected for this post. 
 The scale beam should be kept floating at 
 all times, otherwise all the computations 
 for D. H. P. will have no good foundation. 
 When making a brake test of any duration, 
 or when the engine is a large one, running 
 water should be kept on the band while the 
 engine is going. 
 
 On the factory testing floor, it is not cus- 
 tomary to do any more than take the D. H. 
 P., the I. H. P. and the fuel consumption. 
 Sometimes a brake test only is made. It is 
 always best, however, to take a sufficient 
 number of indicator diagrams to determine 
 if the ignition is properly timed and if 
 there is any derangement of the valves. 
 
CHAPTER XXV. 
 
 SELECTION. 
 
 In selecting a gas engine beware, first of 
 all, of the oily tongue of the salesman. 
 Every gas-engine manufacturer makes the 
 ' best gas engine on earth." Yet the mar- 
 ket is overstocked with poor gas engines. 
 To find out what gas engine is best adapted 
 to your special line of work, consult several 
 users of gas engines who are employing the 
 engines for the same class of machinery 
 which you intend to drive. The engine 
 that will give satisfactory service pumping 
 water may be a good engine for running 
 an electric light plant, but it is doubtful if 
 the regulation is sufficiently close for the 
 purpose. On the other hand, the engine 
 having heavy flywheels and a sensitive 
 governing device, built expressly to meet 
 the rigid requirements of an electric lighting 
 service, is too costly a machine to be pur- 
 chased for pumping water, because a cheaper 
 engine will answer the purpose just as well, 
 
and the difference may be placed in the 
 owner's pocket. 
 
 When you go to consult your neighbor 
 with reference to his engine be prepared 
 with questions regarding the operation of 
 the engine, and also make it a point to see 
 the engine in operation and watch it at 
 work. Then find out as nearly as possible 
 how much the engine costs the owner for 
 repairs, and how often and for how long the 
 engine has been laid up for repairs. Deter- 
 mine the time since the engine left the fac- 
 tory, and whether it has been in constant 
 service ever since that time. If the engine is 
 in a filthy condition, or if it is running with 
 its parts out of joint when it is apparent 
 that they could just as well be adjusted to 
 run properly, score a few points in favor of 
 the engine and against the engineer. An 
 engine that will do fairly good work under 
 bad management has something to recom- 
 mend it. If, however, the engine is clean 
 and all possible adjustments made, and yet 
 is running in a noisy, jerky way, score a 
 point against it. 
 
 If the engine is counterbalanced with the 
 counterweights in the flywheel, stand in a 
 position in line with the axis of the cylin- 
 der and observe if the flywheel is running 
 true at the side. If it sways back and forth 
 it is a sign that the crankshaft is not strong 
 
 204 
 
enough to withstand the strain produced 
 by the counterweight. Determine if the 
 bearings give much trouble from overheat- 
 ing, especially when the engine is working 
 under full load. Ask if the' igniter mechan- 
 ism gives much trouble, and if frequent re- 
 newals of its various parts are necessary. 
 In fact, the necessity for the frequent re- 
 newal of any part of the engine is a black 
 mark against it. 
 
 Find out how much attention, 011 an 
 average, the engine requires per day, and 
 just what the nature of this attention is. 
 If the engine is required to run a dynamo 
 as a considerable proportion of its load, 
 watch the lights when the dynamo is run- 
 ning. If the lights show no perceptible 
 winking, when the light is observed indi- 
 rectly, the engine will give satisfactory ser- 
 vice for electric lighting purposes. A good 
 way to test a light is to try to read fine print 
 by it. If the light throbs to too great an 
 extent, the throbbing will be quite distinct 
 and the eyes will quickly tire. If the pres- 
 sure 011 the lines is 100 volts, the swing of 
 the volt-meter needle should not exceed 
 two volts when swaying back and forth. 
 On a 5o-volt circuit this swing should not 
 exceed one volt, or 2% of the pressure, in 
 any case. 
 
 If the engine shakes considerably each 
 
 205 
 
time it receives an impulse, the trouble is 
 due to an insufficient foundation, but if this 
 shaking continues when the engine is run- 
 ning light, i. e., between explosions, the 
 effect is due to improper balancing. 
 
 In general, select an engine with the 
 fewest number of parts, and with the parts 
 so arranged that they maybe easily reached 
 in case of accident or when repairs of any 
 kind are necessary. Don't think, because 
 the parts are encased, that the engine is a 
 simple one, for the opposite may be the 
 case. An engine with an enclosed mechan- 
 ism may be a very good one for all that. 
 The point that the writer wishes to impress 
 upon the reader is, that it should not be 
 necessary to pull the entire engine to pieces 
 in order to make some insignificant repair 
 or adjustment. 
 
 206 
 
LENGTH OF A CYLINDRICAL TANK REQUIRED 
 TO HOLD ONE GALLON. 
 
 Diam. 
 
 Length 
 
 Diam 
 
 
 Length 
 
 Ft. 
 
 In. 
 
 per gal. 
 in feet. 
 
 Ft. In. 
 
 per gal. 
 in feet. 
 
 1 
 
 
 .1704 
 
 11 
 
 
 .00141 
 
 1 
 
 3 
 
 .108 
 
 11 
 
 8 
 
 .00131 
 
 1 
 
 6 
 
 .0756 
 
 11 
 
 (') 
 
 .00129 
 
 1 
 
 9 
 
 .0556 
 
 11 
 
 9 
 
 .00123 
 
 2 
 
 
 .043 
 
 12 
 
 
 .00118 
 
 > 
 
 3 
 
 .0337 
 
 12 
 
 3 
 
 .00113 
 
 2 
 
 6 
 
 .0273 
 
 12 
 
 C> 
 
 .00109 
 
 2 
 
 9 
 
 .0225 
 
 12 
 
 9 
 
 .00105 
 
 3 
 
 
 .0189 
 
 13 
 
 
 .00101 
 
 3 
 
 3 
 
 .0161 
 
 13 
 
 ;; 
 
 .000970 
 
 3 
 
 6 
 
 .0139 
 
 13 
 
 6 
 
 .000934 
 
 3 
 
 9 
 
 .0121 
 
 13 
 
 9 
 
 .000901 
 
 4 
 
 
 .0106 
 
 14 
 
 
 .000868 
 
 4 
 
 3 
 
 .00943 
 
 14 
 
 3 
 
 .000838 
 
 4 
 
 6 
 
 .00841 
 
 14 
 
 6 
 
 .000809 
 
 4 
 
 9 
 
 .00755 
 
 14 
 
 9 
 
 .000782 
 
 5 
 
 
 .00681 
 
 1") 
 
 
 .000756 
 
 5 
 
 3 
 
 .00617 
 
 15 
 
 3 
 
 .000732 
 
 5 
 
 6 
 
 .00564 
 
 15 
 
 6 
 
 .000708 
 
 5 
 
 9 
 
 .00515 
 
 15 
 
 9 
 
 .000686 
 
 6 
 
 
 .00472 
 
 16 
 
 
 .000665 
 
 6 
 
 3 
 
 .00435 
 
 li 
 
 3 
 
 .000645 
 
 6 
 
 . 6 
 
 .00403 
 
 l(i 
 
 6 
 
 .000(525 
 
 i; 
 
 9 
 
 .00374 
 
 16 
 
 9 
 
 .000606 
 
 7 
 
 
 .00347 
 
 17 
 
 
 .000589 
 
 7 
 
 3 
 
 .00323 
 
 17 
 
 3 
 
 .000572 
 
 7 
 
 6 
 
 .00303 
 
 17 
 
 6 
 
 .000556 
 
 7 
 
 9 
 
 .00283 
 
 17 
 
 9 
 
 .000540 
 
 8 
 
 
 .00266 
 
 IS 
 
 
 .000525 
 
 s 
 
 3 
 
 .00250 
 
 18 
 
 
 .000511 
 
 8 
 
 6 
 
 .00235 
 
 18 
 
 6 
 
 .000497 
 
 8* 
 
 9 
 
 .00222 
 
 18 
 
 9 
 
 .000484 
 
 9 
 
 
 .00210 
 
 19 
 
 
 .000471 
 
 9 
 
 3 
 
 .00199 
 
 19 
 
 3 
 
 .000459 
 
 9 
 
 6 
 
 .00189 
 
 19 
 
 6 
 
 .0004 IS 
 
 9 
 
 9 
 
 .00179 
 
 19 
 
 9 
 
 .000437 
 
 10 
 
 
 .00170 
 
 20 
 
 
 .000426 
 
 10 
 
 3 
 
 .00162 
 
 20 
 
 3 
 
 .00041.". 
 
 10 
 
 6 
 
 .00154 
 
 20 
 
 6 
 
 .000405 
 
 10 
 
 9 
 
 .00147 
 
 20 
 
 9 
 
 .000395 
 
g 
 
 w 
 
 JH 
 ^ 
 
 </} 
 
 3 
 
 I 
 
 fi- 
 
 3 
 
 
 
 rf 
 M 
 
 Jl 
 O 
 
 
 
 IIU* 
 
 -2* 
 
 R.d r 
 
 l-COXJ^^i-ii-li-Hr-^CCXXXXXXJXX 
 
 II 
 
 THr-KNC^OOL^r>CiO^^GCC-X 
 
 1C O OS O CO '-b OS CO 10 X X" 00 CO ?0 O X Tt "T 
 O T I r-J CO 1C 30 "^ O CO 1 . CC CO I- Oi Ci CC I> O 
 
 T-KMro^t^ocato^^ooo 
 
 ^-- i - 
 i-('MCOT}HLOCOO'M 
 
 II 
 
 5 1C iC lO 
 - rjl iO i I O 1^- r 
 
 5 00 O CC O C5 C t X ' T 
 
 Nom 
 Inter 
 
 208 
 
CIRCUMFERENCES AND AREAS 
 OF CIRCLES 
 
 ADVANCING BY EIGHTHS. 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 1-64 
 
 .04909 
 
 .00019 
 
 1. 
 
 3.1416 
 
 .7854 
 
 1-32 
 
 .09818 
 
 .00077 
 
 1-16 
 
 3.3379 
 
 .XS66 
 
 3-64 
 
 .14726 
 
 .00173 
 
 y& 
 
 3.5343 
 
 .9940 
 
 1-16 
 
 .19635 
 
 .00307 
 
 3-16 
 
 3.7306 
 
 1.1075 
 
 3-32 
 
 .29452 
 
 .00690 
 
 M 
 
 3.9270 
 
 1.2272 
 
 /^ 
 
 .39270 
 
 .01227 
 
 5-16 
 
 4.1233 
 
 1.3530 
 
 5-32 
 
 .49087 
 
 .01917 
 
 'A/ 
 
 4.3197 
 
 1.4849 
 
 3-16 
 
 .58905 
 
 .02761 
 
 7-16 
 
 4.5160 
 
 1.6230 
 
 7-32 
 
 .68722 
 
 .03758 
 
 1^ 
 
 4.7124 
 
 1.7671 
 
 
 
 
 9-16 
 
 4.9087 
 
 1.9175 
 
 34 
 
 .78540 
 
 .04909 
 
 5 /s 
 
 5.10'VL 
 
 2.0739 
 
 9-32 
 
 .88357 
 
 .06213 
 
 11-16 
 
 5.3014 
 
 2.2365 
 
 5-16 
 
 .98175 
 
 .07670 
 
 % 
 
 5.4978 
 
 2.4053 
 
 11-32 
 
 1.0799 
 
 .09281 
 
 13-16 
 
 5.6941 
 
 2.5802 
 
 % 
 
 1.1781 
 
 .11045 
 
 % 
 
 5.8905 
 
 2.7612 
 
 13-32 
 
 1.2763 
 
 .121)62 
 
 15-16 
 
 6.0868 
 
 2.Dls:-5 
 
 7-16 
 
 1.3744 
 
 .15033 
 
 
 
 
 15-32 
 
 1.4726 
 
 .17257 
 
 >. 
 
 6.2832 
 
 3.1416 
 
 
 
 
 1-16 
 
 6.4795 
 
 3.3410 
 
 X 
 
 1.5708 
 
 .19635 
 
 i ' 
 
 6.6759 
 
 3.5466 
 
 17-32 
 
 1.66DO 
 
 .22166 
 
 3-16 
 
 6.8722 
 
 : 5. 75s: 5 
 
 9-16 
 
 1.7(571 
 
 .24850 
 
 I/ 
 
 .0686 
 
 3i97Cl 
 
 19-32 
 
 1.865:5 
 
 .276S8 
 
 5-16 
 
 .264!) 
 
 4.20CO 
 
 % 
 
 1.9635 
 
 .30680 
 
 :|/ 
 
 .4613 
 
 4.4301 
 
 21-32 
 
 2.0617 
 
 .33824 
 
 7-16 
 
 .6576 
 
 1.66C1 
 
 11-16 
 
 2.1598 
 
 .37122 
 
 1 A 
 
 7.8540 
 
 4.90F7 
 
 23-32 
 
 2.2580 
 
 .40574 
 
 9-] 6 
 
 S.050. , 
 
 5.1572 
 
 
 
 
 5^ 
 
 8.2467 
 
 5.4110 
 
 M 
 
 2.3562 
 
 .44179 
 
 11-16 
 
 8.44:50 
 
 5.6727 
 
 25-32 
 
 2.4544 
 
 .479:57 
 
 /4 
 
 8.6394 
 
 5.9396 
 
 13-16 
 
 2.5525 
 
 .51849 
 
 13-16 
 
 8.8357 
 
 6.2T26 
 
 27-32 
 
 2.6507 
 
 .55914 
 
 i/ 
 
 9.0:521 
 
 ().4918 
 
 29-32 
 
 2.7489 
 2.8471 
 
 .60132 
 .64504 
 
 15-16 
 
 9.2284 
 
 6.7771 
 
 15-16 
 
 2.9452 
 
 .69029 
 
 3. 
 
 9.4248 
 
 7.06S6 
 
 31-32 
 
 3.04:54 
 
 .73708 
 
 1-16 
 
 9.6211 
 
 7.3662 
 
 209 
 
CIRCUMFERENCES AND AREAS Continued. 
 
 Diam. 
 
 Circum 
 
 Area. 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 ' 3-16 
 
 9.8175 
 10.014 
 
 7.6699 
 7.9798 
 
 13-16 
 
 18.064 
 18.261 
 
 25.967 
 26.535 
 
 IX" 
 
 10.210 
 
 8.2958 
 
 % 
 
 18.457 
 
 27.109 
 
 5-16 
 
 10.407 
 
 8.6179 
 
 15-16 
 
 18.653 
 
 27.688 
 
 '.y 
 
 10.603 
 
 8.9462 
 
 
 
 
 7-16 
 
 10.799 
 
 9.2806 
 
 6. 
 
 18.850 
 
 28.274 
 
 i/ 
 
 10.996 
 
 9.6211 
 
 i/ 
 
 19.242 
 
 29.465 
 
 9-16 
 
 11.192 
 
 9.9678 
 
 ~y 
 
 19.635 
 
 30.680 
 
 5/ 
 
 11.388 
 
 10.321 
 
 % 
 
 20.028 
 
 31.919 
 
 11-16 
 
 11.585 
 
 10.680 
 
 1/2 
 
 20.420 
 
 33.183 
 
 13-16 
 
 11.781 
 11.977 
 
 11.045 
 11.416 
 
 P 
 
 20.813 
 21.206 
 
 34.472 
 35.785 
 
 
 12.174 
 
 11.793 
 
 % 
 
 21.598 
 
 37.122 
 
 15-16 
 
 12.370 
 
 12.177 
 
 
 
 
 
 
 
 7. 
 
 21.991 
 
 38.485 
 
 4. 
 
 12.566 
 
 12.566 
 
 }'$ 
 
 22.384 
 
 39.871 
 
 1-16 
 
 12.763 
 
 12.962 
 
 % 
 
 22.776 
 
 41.282 
 
 YB 
 
 12.959 
 
 13.364 
 
 % 
 
 23.169 
 
 42.718 
 
 3-fe 
 
 13.155 
 
 13.772 
 
 Yi 
 
 23.562 
 
 44.179 
 
 % 
 
 13.352 
 
 14.186 
 
 / 
 
 23.955 
 
 45.664 
 
 5-16 
 
 13 548 
 
 14.607 
 
 3^ 
 
 24.347 
 
 47.173 
 
 '*% 
 
 13.744 
 
 15.033 
 
 /& 
 
 24.740 
 
 48.707 
 
 7^16 
 
 13.941 
 
 15.466 
 
 
 
 
 
 14.137 
 
 15.904 
 
 8. 
 
 25.133 
 
 50.265 
 
 9 7 16 
 
 14.334 
 
 16.349 
 
 i '\ 
 
 25.525 
 
 51.849 
 
 /^ 
 
 14.530 
 
 16.800 
 
 / 
 
 25.918 
 
 53.456 
 
 11-16 
 
 14.726 
 
 17.257 
 
 '% 
 
 26.311 
 
 55.088 
 
 
 14.923 
 
 17.728 
 
 % 
 
 26.704 
 
 56.745 
 
 13-16 
 
 15.119 
 
 18.190 
 
 % 
 
 27.096 
 
 58.426 
 
 /8 
 
 15.315 
 
 18.665 
 
 d/ 
 
 27.489 
 
 60.132 
 
 15-16 
 
 15.512 
 
 19.147 
 
 % 
 
 27.882 
 
 61.862 
 
 -1. 
 
 15.708 
 
 19.635 
 
 9. 
 
 28.274 
 
 63.617 
 
 "l-16 
 
 15.904 
 
 20.129 
 
 % 
 
 28.667 
 
 65.397 
 
 % 
 
 16.101 
 
 20.629 
 
 % 
 
 29.060 
 
 67.201 
 
 3-16 
 
 16.297 
 
 21.135 
 
 II 
 
 29.452 
 
 69.029 
 
 M 
 
 16.493 
 
 21.648 
 
 
 29.845 
 
 70.882 
 
 5-16 
 
 16.690 
 
 22.166 
 
 a 
 
 30.238 
 
 72.760 
 
 % 
 
 16.886 
 
 22.691 
 
 3^ 
 
 30.631 
 
 74.662 
 
 7-16 
 
 17.082 
 
 23.221 
 
 /8 
 
 31.023 
 
 76.589 
 
 i/ 
 
 17.279 
 
 23.758 
 
 
 
 
 9-16 
 
 17.475 
 
 24.301 
 
 10. 
 
 31.416 
 
 78.540 
 
 
 17.671 
 
 24.850 
 
 I/ 
 
 31.809 
 
 80.516 
 
 11-16 
 
 17.868 
 
 25.406 
 
 J;t 
 
 32.201 
 
 82.516 
 
CIRCUMFERENCES AND AREAS Continued. 
 
 Diam. 
 
 t 
 
 Circum. 
 
 Area. 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 10.% 
 
 32.594 
 
 84.541 
 
 15. K 
 
 47.909 
 
 182.65 
 
 
 32.987 
 
 86.590 
 
 '&/ 
 
 48.302 
 
 185.66 
 
 1 
 
 33.379 
 33.772 
 
 88.664 
 90.763 
 
 1 
 
 48.695 
 49.087 
 
 188.69 
 191.75 
 
 7/ 
 
 34.165 
 
 92.886 
 
 'A/ 
 
 49.480 
 
 194.83 
 
 
 
 
 H 
 
 49.873 
 
 197.93 
 
 11. 
 
 34.558 
 
 95.033 
 
 
 
 
 
 34.950 
 
 97.205 
 
 16. 
 
 50.265 
 
 201.06 
 
 l/ 
 
 35.343 
 
 99.402 
 
 i/ 
 
 50.658 
 
 204.22 
 
 % 
 
 35.736 
 
 101.62 
 
 *% 
 
 51.051 
 
 207.3U 
 
 s 
 
 36.128 
 
 103.87 
 
 '%> 
 
 51.444 
 
 210.60 
 
 % 
 
 36.521 
 
 106.14 
 
 i^ 
 
 51.836 
 
 213.82 
 
 % 
 
 36.914 
 
 108.43 
 
 
 
 52.229 
 
 217.08 
 
 J X 8 
 
 37.306 
 
 110.75 
 
 3^ 
 
 52.622 
 
 220.35 
 
 
 
 
 ^8 
 
 53.014 
 
 223.65 
 
 12. 
 
 37.699 
 
 113.10 
 
 
 
 
 i^ 
 
 38.092 
 
 115.47 
 
 17. 
 
 53.407 
 
 226.98 
 
 /* 
 
 38.485 
 
 117.86 
 
 % 
 
 53.800 
 
 230.33 
 
 % 
 
 38.877 
 
 120.28 
 
 i/ 
 
 54.192 
 
 233.71 
 
 H 
 
 39.270 
 
 122.72 
 
 % 
 
 54.585 
 
 237.10 
 
 5/ 
 
 39.663 
 
 125.19 
 
 /-/ 
 
 54.978 
 
 240.53 
 
 '% 
 
 40.055 
 
 127.68 
 
 zi 
 
 55.371 
 
 243.98 
 
 % 
 
 40.448 
 
 130.19 
 
 :{/ i 
 
 55.763 
 
 247.45 
 
 
 
 
 j 
 
 56.156 
 
 250.95 
 
 13. 
 
 40.841 
 
 132.73 
 
 
 
 
 % 
 
 41.233 
 
 135.30 
 
 18. 
 
 56.549 
 
 254.47 
 
 M 
 
 41.626 
 
 137.89 
 
 i/ 
 
 56.941 
 
 258.02 
 
 % 
 
 42.019 
 
 140.50 
 
 /4 
 
 57.334 
 
 261.59 
 
 i^ 
 
 42.412 
 
 143.14 
 
 : Vs 
 
 57.727 
 
 265.18 
 
 
 42.804 
 
 145.80 
 
 1? 
 
 58.119 
 
 268.80 
 
 
 43.197 
 
 148.49 
 
 5/'' 
 
 58.512 
 
 272.45 
 
 /b 
 
 43.590 
 
 151.20 
 
 % 
 
 58.905 
 
 276.12 
 
 
 
 
 % 
 
 59.298 
 
 279.81 
 
 14. 
 
 43.982 
 
 153.94 
 
 
 
 
 ^8 
 
 44.375 
 
 156.70 
 
 19. 
 
 59.690 
 
 283.53 
 
 % 
 
 44.768 
 
 159.48 
 
 i^ 
 
 60.08;; 
 
 287.27 
 
 % 
 
 45.160 
 
 162.30 
 
 /4 
 
 60.476 
 
 291.04 
 
 I/ 
 
 45.553 
 
 165.13 
 
 3/ 
 
 60.868 
 
 294.83 
 
 
 
 45.946 
 
 167.99 
 
 i| 
 
 61.261 
 
 298. 65 
 
 K 
 
 46.338 
 
 170.87 
 
 "> s 
 
 61.654 
 
 302.49 
 
 % 
 
 46.731 
 
 173.78 
 
 :? ( 
 
 62.046 
 
 306.35 
 
 
 
 
 J? 
 
 62.439 
 
 310.24 
 
 15. 
 
 47.124 
 
 176.71 
 
 
 
 
 K 
 
 47.517 
 
 179.67 
 
 20. 
 
 62.832 
 
 314. 1 
 
CIRCUMFKRKNCKS AND ARK AS Continued. 
 
 IMam. 
 
 Circum. 
 
 Area. 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 CO. % 
 
 63 22-) 
 
 31* 10 
 
 2. 
 
 78.540 
 
 490.87 
 
 X 
 
 63.617 
 
 322.06 
 
 Ye 
 
 78.933 
 
 495.79 
 
 % 
 
 (U.010 
 
 326.05 
 
 y* 
 
 79.325 
 
 500.74 
 
 Y* 
 
 04.408 
 
 330.06 
 
 % 
 
 79.718 
 
 505.71 
 
 7* 
 
 61.795 
 
 334.10 
 
 Y 
 
 80.111 
 
 510.71 
 
 i\ 
 
 65.188 
 
 338.16 
 
 % 
 
 80.503 
 
 515.72 
 
 
 65.581 
 
 342.25 
 
 / 
 
 80.896 
 
 520.77 
 
 
 
 
 /Q 
 
 81.289 
 
 525.84 
 
 > | 
 
 C5.973 
 
 346.36 
 
 
 
 
 A^ 
 
 C.'i :)66 
 
 350.50 
 
 26. 
 
 81.681 
 
 P30.93 
 
 y 
 
 <;C).759 
 
 354.66 
 
 YB 
 
 82.074 
 
 536.05 
 
 / 
 
 67.152 
 
 358.84 
 
 H 
 
 82.467 
 
 541.19 
 
 i 
 
 67.544 
 
 (i7.9:57 
 
 363.05 
 367.28 
 
 % 
 
 82.860 
 83.252 
 
 546.35 
 551.55 
 
 :$ 
 
 4 
 
 68.330 
 
 371.54 
 
 5 /8 
 
 83.645 
 
 556.76 
 
 % 
 
 68.722 
 
 375.83 
 
 % 
 
 84.038 
 
 562.00 
 
 
 
 
 Y*. 
 
 84.430 
 
 567.27 
 
 22. 
 
 (>9.115 
 
 380.13 
 
 
 
 
 N 
 
 69.508 
 
 3S4.46 
 
 27. 
 
 84.823 
 
 572.56 
 
 g 
 
 69.900 
 
 388.82 
 
 ', 
 
 85.216 
 
 577.87 
 
 P 
 
 70.293 
 
 393.20 
 
 ', 
 
 85.608 
 
 583.21 
 
 
 70.686 
 
 397.61 
 
 :: , 
 
 86.001 
 
 588.57 
 
 % 
 
 71.079 
 
 402.04 
 
 ^2 
 
 86.394 
 
 593.96 
 
 A 
 
 71.471 
 
 406.49 
 
 H 
 
 86.786 
 
 599.37 
 
 Ys 
 
 71.864 
 
 410.97 
 
 % 
 
 87.179 
 
 604., il 
 
 
 
 
 % 
 
 87.572 
 
 610: ?7 
 
 23. 
 
 72.257 
 
 415.48 
 
 
 
 
 H 
 
 72.649 
 
 420.00 
 
 28. 
 
 87.965 
 
 t>15.7 -> 
 
 8 
 
 73.042 
 
 424.56 
 
 % 
 
 88.357 
 
 621.26 
 
 % 
 
 7:5.435 
 
 429.13 
 
 ', 
 
 88.750 
 
 626.80 
 
 s 
 
 73.827 
 
 4:5: 5.74 
 
 % 
 
 89.143 
 
 632.36 
 
 's 
 
 74.220 
 
 438.36 
 
 '- 
 
 89.535 
 
 637.94 
 
 % 
 
 74.613 
 
 443.01 
 
 :>^ 
 
 89.928 
 
 C.43.55 
 
 
 75.006 
 
 447.69 
 
 %! 
 
 90.321 
 
 649.18 
 
 
 
 
 Ys 
 
 t)0.7i:j 
 
 654.84 
 
 24. 
 
 7.").39S 
 
 452.:5!) 
 
 
 
 
 X 
 
 75.791 
 
 457.11 
 
 29. 
 
 91.106 
 
 660.52 
 
 M 
 
 76.184 
 
 4C.I si; 
 
 i 
 
 ( J1.1!I ( .> 
 
 066.23 
 
 % 
 
 76.576 
 
 4(16.64 
 
 Y4 
 
 91.892 
 
 671.96 
 
 8 
 
 76.969 
 
 471.44 
 
 :; s 
 
 92.284 
 
 677.71 
 
 -* 
 
 77.362 
 
 476.26 
 
 ', 
 
 92.677 
 
 683.49 
 
 ; , 
 
 77.754 
 
 4S1.11 
 
 .-, 
 
 93.070 
 
 689.30 
 
 % 
 
 78.147 
 
 485.98 
 
 '% 
 
 93.462 
 
 695.13 
 
 
 
 
 Y* 
 
 93.855 
 
 700.98 
 
CIRCUMFERENCES AND AREAS Continued. 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 30. 
 
 94.248 
 
 706.86 
 
 35. 
 
 109.956 
 
 962.11 
 
 % 
 
 94.640 
 
 712.76 
 
 Ys 
 
 110.348 
 
 969.00 
 
 V* 
 
 95.033 
 
 718.69 
 
 % 
 
 110.741 
 
 975.91 
 
 % 
 
 95.426 
 
 724.64 
 
 '% 
 
 111.134 
 
 982.84 
 
 H 
 
 95.819 
 
 730.62 
 
 ft 
 
 111.527 
 
 989.80 
 
 n 
 
 96.211 
 
 736.62 
 
 II 
 
 111.919 
 
 99K.78 
 
 % 
 
 96.604 
 
 742.64 
 
 74: 
 
 112.312 
 
 1003.8 
 
 jl 
 
 96.997 
 
 748.69 
 
 % 
 
 112.705 
 
 1010.8 
 
 81. 
 
 97.389 
 
 754.77 
 
 36. 
 
 113.097 
 
 1017.9 
 
 y. 
 
 97.782 
 
 760.87 
 
 H 
 
 113.490 
 
 1025.0 
 
 '4 
 
 98.175 
 
 766.99 
 
 g 
 
 113.883 
 
 1032.1 
 
 < 
 
 98.567 
 
 773.14 
 
 \7 
 78 
 
 114.275 
 
 1039.2 
 
 s 
 
 98.960 
 
 779.31 
 
 ft 
 
 114.668 
 
 1046.3 
 
 jl 
 
 99.353 
 
 785.51 
 
 || 
 
 115.061 
 
 1053.5 
 
 % 
 
 99.746 
 
 791.73 
 
 ^ 
 
 115.454 
 
 1060.7 
 
 % 
 
 100.138 
 
 797.98 
 
 % 
 
 115.846 
 
 1068.0 
 
 32. 
 
 100.531 
 
 804.25 
 
 37. 
 
 116.239 
 
 1075.2 
 
 i/ 
 
 100.924 
 
 810.54 
 
 ^ 
 
 116.632 
 
 1082.5 
 
 '-1 
 
 101.316 
 
 816.86 
 
 % 
 
 117.024 
 
 1089.8 
 
 \ 
 
 101.709 
 
 823.21 
 
 % 
 
 117.417 
 
 1097.1 
 
 H 
 
 102.102 
 
 829.58 
 
 u 
 
 117.810 
 
 1104.5 
 
 ''s 
 
 102.494 
 
 835.97 
 
 XH 
 
 118.202 
 
 1111.8 
 
 i 
 
 102.887 
 
 842.39 
 
 % 
 
 118.596 
 
 1119.2 
 
 % 
 
 103.280 
 
 848.83 
 
 % 
 
 118.988 
 
 1126.7 
 
 38. 
 
 103.673 
 
 855.30 
 
 38. 
 
 119.381 
 
 1134.1 
 
 % 
 
 104.065 
 
 861.7!) 
 
 T-/ 
 
 119.773 
 
 1141.0 
 
 & 
 
 104.458 
 
 86S.31 
 
 % 
 
 120.166 
 
 1149.1 
 
 % 
 
 104.851 
 
 874.85 
 
 % 
 
 120.559 
 
 1156.6 
 
 X 
 
 105.243 
 
 881.41 
 
 % 
 
 120.9ol 
 
 1164.2 
 
 % 
 
 105.636 
 
 888.00 
 
 'V 
 
 121.344 
 
 1171.7 
 
 % 
 
 106.02!) 
 
 894.62 
 
 % 
 
 121.737 
 
 1179.3 
 
 7/8 
 
 106.421 
 
 901.26 
 
 % 
 
 122.129 
 
 1186.9 
 
 34. 
 
 106.814 
 
 907.92 
 
 39. 
 
 122.522 
 
 1194.6 
 
 H 
 
 107.207 
 
 914.61 
 
 i/ 
 
 122.915 
 
 1 202.3 
 
 i 
 
 107.600 
 
 921.32 
 
 4 
 
 123.308 
 
 1210.0 
 
 ' ' s 
 
 107.992 
 
 928.06 
 
 % 
 
 123.700 
 
 1217.7 
 
 K 
 
 108.385 
 
 934.82 
 
 1 
 
 124.093 
 
 1225.4 
 
 ''s 
 
 108.778 
 
 941.61 
 
 
 124.4X6 
 
 1233.2 
 
 :! 4 
 
 109.170 
 
 948.42 
 
 j2 
 
 124.878 
 
 1241.0 
 
 7 .s 
 
 109.563 
 
 955.25 
 
 % 
 
 125.271 
 
 1248.8 
 
 213 
 
CIRCUMFERENCES AND AREAS- -Concluded. 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 40. 
 
 125.664 
 
 1256.6 
 
 45. 
 
 141.372 
 
 1590.4 
 
 H 
 
 126.056 
 
 1264.5 
 
 % 
 
 141.764 
 
 1599.3 
 
 15 
 
 126.449 
 
 1272.4 
 
 & 
 
 142.157 
 
 1608.2 
 
 % 
 
 126.842 
 
 1280.3 
 
 % 
 
 142.550 
 
 1617.0 
 
 YL 
 
 127.235 
 
 1288.2 
 
 A 
 
 142.942 
 
 1626.0 
 
 % 
 
 127.627 
 
 1296.2 
 
 78 
 
 143.335 
 
 1634.9 
 
 % 
 
 128.020 
 
 1304.2 
 
 % 
 
 143.728 
 
 1643.9 
 
 /8 
 
 128.413 
 
 1312.2 
 
 % 
 
 144.121 
 
 1652.9 
 
 41. 
 
 128.805 
 
 1320.3 
 
 46. 
 
 144.513 
 
 1661.9 
 
 H 
 
 129.198 
 
 1328.3 
 
 Ys 
 
 144.906 
 
 1670.9 
 
 i| 
 
 129.591 
 
 1336.4 
 
 % 
 
 145.299 
 
 1680.0 
 
 /9> 
 
 129.983 
 
 1344.5 
 
 >8 
 
 145.691 
 
 1689.1 
 
 J^Z 
 
 130.376 
 
 1352.7 
 
 ft 
 
 146.084 
 
 1698.2 
 
 ftZ 
 
 130.769 
 
 1360.8 
 
 II 
 
 146.477 
 
 1707.4 
 
 % 
 
 131.161 
 
 1369.0 
 
 ft 
 
 146.869 
 
 1716.5 
 
 % 
 
 131.554 
 
 1377.2 
 
 '/8 
 
 147.262 
 
 1725.7 
 
 42. 
 
 131.947 
 
 1385.4 
 
 47. 
 
 147.655 
 
 1734.9 
 
 X 
 
 132.340 
 
 1893.7 
 
 Ys 
 
 148.048 
 
 1744.2 
 
 I/ 
 
 132.732 
 
 1402.0 
 
 H 
 
 148.440 
 
 1753.5 
 
 ? 
 
 133.125 
 
 1410.3 
 
 ' ! s 
 
 U8.X33 
 
 176:2.7 
 
 Iz 
 
 1:58.51 <S 
 
 1418.6 
 
 % 
 
 149.226 
 
 1772.1 
 
 /8 
 
 133.910 
 
 1427.0 
 
 % 
 
 149.618 
 
 1781.4 
 
 3% 
 
 134.303 
 
 1435.4 
 
 % 
 
 150.011 
 
 1790.8 
 
 % 
 
 134.6% 
 
 1443.8 
 
 Ys 
 
 150.404 
 
 1800.1 
 
 43. 
 
 135.088 
 
 1452.2 
 
 48. 
 
 150.796 
 
 1809.6 
 
 Yi 
 
 135.481 
 
 1460.7 
 
 i,' 
 
 151.189 
 
 1819.0 
 
 i/ 
 
 135.874 
 
 1469.1 
 
 ft 
 
 151.582 
 
 182S.5 
 
 3^ 
 
 136.267 
 
 1477.6 
 
 % 
 
 151.975 
 
 1837.9 
 
 1^ 
 
 136.659 
 
 1486.2 
 
 % 
 
 152.367 
 
 1847.5 
 
 S 
 
 137.052 
 
 1194.7 
 
 '\s 
 
 152.760 
 
 1857.0 
 
 /4 
 
 137.445 
 
 1503.3 
 
 % 
 
 153.153 
 
 1866.5 
 
 % 
 
 137.837 
 
 1511.9 
 
 H 
 
 153.545 
 
 1876.1 
 
 44. 
 
 138.230 
 
 1520.5 
 
 49. 
 
 153.938 
 
 1S85.7 
 
 % 
 
 138.623 
 
 1529.2 
 
 Y* 
 
 154.331 
 
 1X95.4 
 
 is 
 
 139.015 
 
 1537.9 
 
 i 
 
 154.723 
 
 1905.0 
 
 '&/ 
 
 139.408 
 
 1546.6 
 
 ''s 
 
 155.116 
 
 1914.7 
 
 \y 
 
 139. SOI 
 
 1555.3 
 
 ft 
 
 155.509 
 
 1924.4 
 
 7 
 
 140.194 
 
 1564.0 
 
 Ys 
 
 155.902 
 
 193 J. 2 
 
 74 
 
 140.586 
 
 1572.8 
 
 % 
 
 156.294 
 
 194:5.9 
 
 % 
 
 140.979 
 
 1581.6 
 
 % 
 
 156.687 
 
 195:5.7 
 
 2T4 
 
INDEX. 
 
 PAGE 
 
 Areas of circles, table of 209 
 
 Automobile engines 103 
 
 Automobile engines, cooling cylinders of .... 105 
 
 Automobile engines, power of 104 
 
 "Backfiring" 37 
 
 Balance-weights 167 
 
 Balance-weights, formulas for 169 
 
 Balance- weights, location of 169 
 
 Barometer, use of in testing 182 
 
 Batter, in foundations 175 
 
 Battery, care of 30 
 
 Battery cells 38 
 
 Beau de Rochas' propositions 1 
 
 Brake arm, determination of effect of 200 
 
 British thermal unit, definition of ....... 198 
 
 Camshaft, formula for 177 
 
 (Jam, laying out a 78 
 
 ( -amshaf t, position of 7s 
 
 Carbon, deposits of in cylinder 37 
 
 Carbureters 42, 44 
 
 Carbureter, defects of 51 
 
 Carbureter, heating a 50 
 
 Care of an engine 27 
 
 Cells for battery 3s 
 
 Circumferences of circles, table of 20!' 
 
 Clearance, percentage of 19 1 
 
 Clerk's two-cycle engine 5, <> 
 
 215 
 
PAGE 
 
 Coal, for gas producer '. . 18 
 
 Condenser, use of 03 
 
 Connecting-rod 151 
 
 Connecting-rod, formulas for 152 
 
 Connecting-rod, proportions of . . 150 
 
 Con tact points, destruction of 6:5 
 
 Cooling tanks, evaporation in, per I. H. P 177 
 
 Cooling tanks, size of. 177 
 
 Crank-pin, formula for -. . . 154 
 
 Crankshafts 153 
 
 Crankshafts, formulas for lf>;',, 154 
 
 Crankshaft, proportions of 155 
 
 Cylinder, formulas for diameter of .... 123, 126, 127 
 
 Cylinder, proportions of 129-134 
 
 Cylinder head 134 
 
 Day engine 6, 7, 70 
 
 Diagrams 108 
 
 Diagrams, examples of actual. fc . 116, 117 
 
 Diagrams, formulas for 110, 111 
 
 Diagram from gasoline engine 120 
 
 Diagram, size of 181 
 
 Diesel cycle, comparison with others 15 
 
 Diesel cycle, principles of operation of the . . . 9-12 
 
 Dimensions of a gas engine 121 
 
 Efficiency, thermal ' 199 
 
 Electric lights, fluctuation of light in 205 
 
 Energy, storage of 101 
 
 Engine, shaking of 20^ 
 
 Exhaust gases, heat carried off by 19s 
 
 Explosion, cause of weak , 36 
 
 Explosions, in exhaust passages 36 
 
 Explosions, premature 37 
 
 Flame, color of 3.> 
 
 Flame, trouble with 38 
 
 Flywheel, computing weight of ... 162 
 
 Flywheel, diameter of 166 
 
 Flywheel, formula for 163 
 
 Flywheel, proportions of 165 
 
 216 
 
PAGE 
 
 Flywheels; 1M 
 
 Foundation bolts, formula for 176 
 
 Foundations 171 
 
 Foundations, formula for weight of 17:'! 
 
 Foundations, location of 172 
 
 Foundations, materials for 171 
 
 Four-cycle, comparison with others 18 
 
 Four-cycle engine, principles of operation . . . 2, 3, 5 
 
 Frame 157 
 
 Fuel, power derived from 17 
 
 Fuels 17-20 
 
 Fuels, table of -'I 
 
 Gases, specific heat of 195 
 
 Gases, weight of 19.~> 
 
 Gasoline engine, power of a 19, 41 
 
 Gasoline engines 41 
 
 Gasoline engines, attachments for 42-48 
 
 Gasoline engine, handling a 49 
 
 Gasoline engine, starting a 49 
 
 Gasoline engine, time of ignition in 50 
 
 Gasoline fires, how to extinguish 53 
 
 Gasoline, power derived from 19 
 
 Gasoline, precautions in handling 51 
 
 Gasoline, storage of 52 
 
 Gasoline tanks, construction of 52 
 
 Gasoline tanks, explosions in 52 
 
 Gas producer 18 
 
 Gas valve, adjustment of 33 
 
 Gears, types in use 8:-! 
 
 Governors 87 
 
 Governors, adjustment and care of 33 
 
 Governors, examples of 92-% 
 
 Heat absorbed by jacket water 197 
 
 Heat absorbed in work 1.97 
 
 Heat carried off by exhaust gases 198 
 
 Heat values, table of 21 
 
 Hornsby-Akroyd engine - r >9 
 
 Horsepower, formulas for 123, 200 
 
 217 
 
PAGE 
 
 Igniter, adjustment of :\t\ 
 
 Igniter, match 100 
 
 Igniter, setting of 2s 
 
 Igniters 54 
 
 Ignition, methods of 54 
 
 Ignition, premature 37 
 
 Ignition tubes . 31 
 
 Indicators isi 
 
 Jacket water, flow of . . 177 
 
 Jacket water, heat absorbed by 197 
 
 Jacket water, management of 32 
 
 Jacket water, measurement of isr> 
 
 Jacket water, range of temperature in 194 
 
 Jets 44, 4<;, 59 
 
 Jump-spark 67 
 
 Kerosene engines, vaporizer for 50 
 
 Leaks, remedies for :'.9 
 
 Make-and-break igniter . . 65, 67 
 
 Manometer 1*2 
 
 Marine engine, formula for size of 17.S 
 
 Mean effective pressure, determination of .... 199 
 
 Meter for testing 1*1 
 
 Muffler, formula for 177 
 
 Nash engine > 
 
 Otto cycle 2. 
 
 Oil, crank-case 29 
 
 Oil, cylinder 29 
 
 Oil, lubricating 28 
 
 Pipe, table of gas and water 20s 
 
 Piston, care of - 3:i 
 
 Piston-pin, formula for 151 
 
 Piston, proportions of 1 IS 
 
 Piston rings 1 17 
 
 Piston-rods in gas engines 1 1<> 
 
 Piston, trunk 1 17 
 
 Plauimeter, use of 19'.' 
 
 Pounding, cause of 39 
 
 Power, loss of :>9 
 
 2lS 
 
PAGE 
 
 Premature explosions 37 
 
 Pressure, coefficients for reduction of 197 
 
 Prony brake isi 
 
 Propellers, formula for 178 
 
 Pyrometer 182 
 
 Katio of gas to air 194 
 
 Resistance, non-inductive 63 
 
 Scale, testing a platform 181 
 
 Selection 20:1 
 
 Slowing down, cause of ;;6 
 
 Smoke, cause of 39 
 
 Soot, in exhaust passages 29 
 
 Spark, cause of weak 38 
 
 Speed, formulas for 12.~> 
 
 Speed variation Kid 
 
 Speed variation, allowable 16.5 
 
 Springs, adjustment of 30, 3<; 
 
 Starting, rules for 22 
 
 Starters 97 
 
 Stopping, rules for 25 
 
 Suction valve 71 
 
 Table of areas and circumferences of circles . . . 209 
 
 Table of capacity of cylindrical vessels 207 
 
 Table of gas and water pipe 208 
 
 Table of heat values 21 
 
 Tanks, table of capacity of cylindrical 207 
 
 Temperature, formula for reduction to standard . 196 
 
 Temperature, reduction to standard 196 
 
 Test, apparatus for 181, 183 
 
 Test, customary determinations in a factory . . . 202 
 
 Test, log for 188 
 
 Test, measurements for 190 
 
 Test, method of conducting a 187 
 
 Test, number of runs in a 189 
 
 Test, objects of f , ISO 
 
 Test, report of ! 192,19:; 
 
 Testing 180 
 
 Thermal efficiency 199 
 
 219 
 
Thermometers 1 s - 
 
 Timing valve 5s 
 
 Tubes, material for ignition 31 
 
 Tubes, proper temperature for ignition 31 
 
 Troubles, gas-engine 35 
 
 Two-cycle, comparison with others 14 
 
 Two-cycle engine, principles of operation ... 7, i> 
 
 Valves, arrangement of 141-145 
 
 Valve boxes, examples of 141-145 
 
 Valves, leaks in :!0, :' 
 
 . Valve mechanisms 73 
 
 Valves, proportions of 139, HO 
 
 Valves, size of 136-139 
 
 Valve-stems, care of 34, 40 
 
 Vaporizers 4-J, 4f> 
 
 Water, flow of in jacket 177 
 
 Water, formula for weight of ]!>! 
 
 Water-jacket, deposit in 29 
 
 Water, measurement of jacket 1*5 
 
 Water pipe, table of 20s 
 
 Weak spark, cause of :->* 
 
 Wipe break 63,07 
 
 Work, heat absorbed by 197 
 
 220 
 
1 
 
 
 
 
 **, The... 
 
 "WATKINS" 
 
 
 GAS AND GASO- 
 
 
 
 LINE ENGINES* 
 
 
 
 
 
 *jf 
 
 Only Engine using 
 
 
 
 cMagneto 
 Generator 
 
 
 
 No Hot Tubes. 
 
 
 
 No ^Batteries. 
 
 
 
 Descriptive Catalogue on application. 
 
 
 F. ML WATKINS, 
 
 
 309 West Fourth Street, 
 
 
 
 CINCINNATI, OHIO. 
 
 
 
 
GASOLINE 
 ENGINES.. 
 
 STATIONARY, CARRIAGE AND 
 LAUNCH ENGINES. 
 
 VL to 4 H P * Flange-Cooled and 
 
 r Water-Jacketed Cylinders. 
 
 CARBURETORS, 
 
 GASOLINE MIXING VALVES, 
 
 PROPELLER WHEELS and SHAFTS. 
 
 Also complete sets of Castings of Gasoline 
 Engines, with Forgings, Screws and Working 
 Drawings, either in rough or partly ma- 
 ehined, as required. 
 
 LOWELL MODEL CO., 
 
 P. O. BOX 292, - - LOWELL, MASS. 
 
GAS 
 
 If you have a Gas Engine, send 
 for a sample of QJXON'S 
 
 No. 635 GRAPHITE. 
 
 It will lubricate your Gas Engine Cylinder better 
 than oil. It is not affected by heat. 
 
 JOSEPH DIXON CRUCIBLE CO. 
 
 JERSEY CITY, N.J. 
 
 PATENTS 
 
 secured in the United 
 States and foreign coun- 
 
 mmmmmmmmmmi^^fmmmi^i^t trieS. Investigations aS 
 
 to novelty and validity. Litigation conducted 
 in the Courts and Patent Office. Trade Marks 
 registered. Members of the bar of the United 
 States Supreme Court and various Circuit Courts. 
 
 BALDWIN, DAVIDSON & WIGHT, 
 
 25 Grant Place, 
 
 WASHINGTON, D. C. 
 
 141 Broadway, 
 
 NEW YORK. 
 
 THERE/A LITTLE BOOK-TELL/ WHV 
 
 " WHICH WAY" POCKET LEVEL.. 
 
 TELLS in an instant "WHICH 
 WAY" your work is out. See? 
 It is the size of a silver dollar and 
 three - eighths thick. Nicely 
 nickeled and polished. To in- 
 troduce it, will mail one for 70c. 
 in stamps or three for $2.00. Caliper catalog free. 
 
 E. G. SMITH, Columbia, Pa., U. S. A. 
 
Attractive Catalogues 
 ^ Carefully Edited^ 
 
 "WTE offer a service that is 
 W unsurpassed, including 
 p r i n t i n g , half tones, 
 wood engravings and the best 
 typographical display* A me- 
 chanical engineer of demon- 
 strated ability, who is a for- 
 cible writer on mechanical 
 subjects, and of wide experi- 
 ence, is specially engaged to 
 do the editing* We make a 
 specialty of catalogues that 
 will catch the attention of the 
 reader at the start and retain 
 his interest until he has read 
 the entire pamphlet* Make 
 your catalogue not only a 
 work of art, but put informa- 
 tion in it that the recipient 
 will wish to keep* Write us 
 for estimates* We know that 
 we can please you* Address 
 
 The Ohio Printing Co*, 
 
 330 W. 9th Street, - - Cincinnati, Ohio. 
 
The Mietz & Weiss 
 
 KEROSENE ENGINE 
 
 [Patented.] 
 
 COMMON KEROSENE ITS FUEL. 
 
 % CENT PER HORSEPOWER PER HOUR. 
 IGNITES BY COMPRESSION. 
 
 MOST ECONOMICAL AND SAFEST 
 POWER KNOWN 
 
 128-132 MOTT ST., 
 NEW YORK. 
 
 MARKT &, COMPANY, LTD., 
 
 EUROPEAN AGENTS. 
 
 LONDON. HAMBURG. PARIS. 
 
WORKING DRAWINGS FOR SALE, 
 
 0a$ and Gasoline Engines 
 
 Horizontal, Stationary, - - - - 12 sizes. 
 Vertical and Marine, ."-."- 4 sizes. 
 
 Steam Engines. 
 
 Corliss, simple and compound, - - 12 sizes. 
 
 Center Crank, 4 sizes. 
 
 Ant, High-Speed, - - - - 10 sizes. 
 
 QIDDINQS & STEVENS, 
 
 Mechanical Engineers, ROCKPORD, ILL. 
 
 There are 10,000 Laundries in 
 the United States and Canada. 
 
 THE STARCHROOM 
 
 LAUNDRY JOURNAL 
 
 Write for rates. Covers the Entire Trade. 
 
 The Starch room Publishing Co., 
 
 Cincinnati, Ohio. 
 
Cbe 6as Engine 
 
 magazine. 
 
 Stationary, 
 
 marine, 
 
 flutomobik. 
 
 Devoted 10 the interests of an up-to-date power. 
 illustrated. 
 
 edited by G. 01. Roberts, 
 
 the 6a$ engine contains tbe latest news 
 
 relating to tbe das engine and 
 
 tbe automobile. 
 
 Special Teatum, 
 
 '^ e e( ^^ " a ^ s 8 lve a monthly 
 review of the gas engine situation 
 in general. 
 
 Special Articles, s P edal articles a pp ar 
 
 each month which deal 
 with the gas engine and kindred subjects. 
 
foreign Correspondence, We hav * just 
 
 made arrange- 
 ments with a well-known expert in Europe to keep 
 our readers informed on the latest developments 
 across the Atlantic. 
 
 TtettlS. e industrial columns 
 
 contain information re- 
 
 garding new enterprises. 
 
 Automobile news, This column gives se 
 
 lected items of news, 
 relating to automobiles. 
 
 The inquiry column is at the 
 service of our subscribers, and is 
 one of the most valuable features of the magazine. 
 All questions are answered carefully and in full. 
 
 The gas engine is, without a shadow of doubt, the 
 power par excellence of the Twentieth Century. 
 Engineers and mechanics, the world over, are studying 
 its developments with interest. The Gas Engine is 
 the only publication in the English language devoted 
 to this subject. It will keep you informed, and at 
 the insignificant outlay of $1.00 each year for the 
 twelve issues. Send for a sample copy to THE 
 GAS ENGINE PUBLISHING CO., Goodall Build- 
 ing, Cincinnati, Ohio. 
 
i"J< 
 
THIS BOOK IS DUE ON THE LAST DATE 
 STAMPED BELOW 
 
 AN INITIAL PINE OP 25 CENTS 
 
 WILL dE ASSESSED FOR FAILURE TO RETURN 
 THIS BOOK ON THE DATE DUE. THE PENALTY 
 WILL INCREASE TO SO CENTS ON THE FOURTH 
 DAY AND TO $!.OO ON THE SEVENTH DAY 
 OVERDUE. 
 
 SEP 27 1939 
 
UNIVERSITY OF CALIFORNIA LIBRARY