,transcriber's ,notes ,text printed in italics or bold face in the source document have been transcribed between underscores and equal signs respectively4 ,small capitals have been replaced with ,,all ,,capitals4 ,characters between tildes represent the shape of the character rather than the character itself4 ,more ,transcriber's ,notes and a list of changes made to the text may be found at the end of this text4 ,illustration3 ,plate ,,ii4 ,,longitudinal ,,section ,,of ,,american ,,locomotive4 ,by ,the ,grant ,locomotive ,works1 ,paterson1 ,new ,jersey4 ,scale1 in4 #a foot4 ,illustration3 ,plate ,,iii4 ,,plan ,,of ,,american ,,locomotive4 ,by ,the ,grant ,locomotive ,works1 ,paterson1 ,new ,jersey4 ,scale1 in4 #a foot4 ,,catechism ,,of ,,the ,,locomotive ,illustration3 #ahhf ,,by ,,matthias ,n4 ,,forney1 ,mechanical ,engineer4 ,will be sent by mail1 postage prepaid1 on receipt of price #b4ej4 ,,frederick ,,keppy1 ,scientific ,book ,publisher1 ,no4 #ch ,,state ,,street1 ,,bridgeport1 ,,conn4 ,entered1 according to ,act of ,congress1 in the year #ahgd1 by ,,the ,,railroad ,,gazette1 ,in the office of the ,librarian of ,congress1 at ,washington4 ,,preface4 ,books1 like individuals1 have their histories1 and it seems but proper that in introducing them somewhat of their ancestry should be detailed4 ,the present book originated in this wise3 the publishers of the ,,railroad ,,gazette procured a copy of the 8,katechismus der ,einrichtung und des ,betriebes der ,locomotive10 by ,georg ,kosak4 ,as no ,english translation of this excellent little book was known to be in existence1 the editors of the above paper determined to translate it and adapt it to the ,american practice in the construction and management of locomotive steam engines1 and republish it in their journal4 ,the translation was therefore made and submitted to the writer for revision and adaptation1 according to the original intention4 ,before the latter was entertained1 however1 he had commenced writing an elementary treatise on the locomotive4 ,in revising the first part of the translation of ,mr4 ,kosak's book1 it was found that the latter occupied only to a very limited extent the ground which the writer had 8staked out0 in his own incomplete plan4 ,he therefore concluded to abandon the original intention of 8adapting0 ,mr4 ,kosak's work1 and determined to rewrite it and make substantially a new book of it4 ,for the 8idea10 however1 and to some extent its plan1 and for much valuable material1 the author must acknowledge his indebtedness to ,mr4 ,kosak4 ,in some few cases the language of the translator has been employed1 in part or in whole1 without quotation marks1 but with an acknowledgment in a foot-note4 ,a similar plan has also been pursued in using some other books4 ,this was done to avoid cutting up paragraphs and sentences into fragmentary parts with numerous quotation marks4 ,the following books have been consulted and used in writing the ,catechism of the ,locomotive3 ,heat considered as a ,mode of ,motion1 by ,prof4 ,tyndall2 ,the ,conservation of ,energy1 by ,balfour ,stewart2 ,railway ,machinery1 by ,d4 ,k4 ,clark2 ,treatise on the ,locomotive ,engine1 by ,zerah ,colburn2 ,treatise on the ,steam ,engine1 by ,w4 ,j4 ,m4 ,rankine2 ,indicator ,experiments on ,locomotives1 by ,professor ,bauschinger2 ,richards' ,steam ,indicator1 by ,charles ,t4 ,porter2 ,die ,schule des ,locomotivfhrers1 by ,j4 ,brosius and ,r4 ,koch2 ,mechanics1 by ,a4 ,morin2 ,the ,new ,chemistry1 by ,j4 ,p4 ,cooke1 ,jr42 ,combustion of ,coal and the ,prevention of ,smoke1 by ,c4 ,wye ,williams2 ,a ,treatise on ,steam ,boilers1 by ,robert ,wilson2 ,reports of the ,american ,railway ,master ,mechanics' ,association2 ,link ,valve ,motion1 by ,william ,s4 ,auchincloss1 and ,emergencies and ,how to ,treat ,them1 by ,dr4 ,joseph ,w4 ,howe4 ,for the title of the book an apology is perhaps needed1 as the word ,catechism is associated in nearly all persons' minds we will trust with early religious and theological instruction1 and therefore a ,catechism of the ,locomotive is very apt to sound more ludicrous than scientific4 ,the title of ,mr4 ,kosak's book was adopted before it was determined to rewrite it1 and it was afterwards not deemed best to change it4 ,to those who are disposed to smile at it1 the precedent of ,mr4 ,bourne's excellent ,catechism of the ,steam ,engine is quoted1 and if they will refer to ,webster's ,dictionary for the definition of the word 8catechism10 they will find that it means 8an elementary book containing a summary of principles in any science or art1 but appropriately in religion1 reduced to the form of questions and answers1 and sometimes with notes1 explanations and reference to authorities10 which is exactly what the present book is intended to be4 ,to persons accustomed to books and study1 the catechetical form is very apt to seem cumbrous and awkward1 but it has some very decided advantages in writing for those who have not acquired studious habits of thought4 ,to such the question asked presents first a distinct image of the subject to be considered1 so that the explanation or instruction which follows is much more apt to be understood than it would be if no such question had been asked4 ,the author is indebted to ,mr4 ,d4 ,b4 ,grant for the use of drawings from which most of the engravings of details of locomotives with which this book is illustrated have been made1 and to other locomotive builders1 whose engines are illustrated in the full-page plates1 for the drawings thereof4 ,he has also received very valuable aid from ,mr4 ,richard ,h4 ,buel1 ,mechanical ,engineer2 ,mr4 ,william ,buchanan1 ,master ,mechanic of the ,hudson ,river ,railroad2 ,mr4 ,frank ,d4 ,child1 ,superintendent of the ,hinkley ,locomotive ,works2 and ,mr4 ,e4 ,t4 ,jeffrey1 ,assistant ,superintendent of ,machinery of the ,illinois ,central ,railroad4 ,the object in writing the book was to furnish a clear and easily understood description of the principles1 construction and operation of the locomotive engine of the present day1 a subject which is not concisely or adequately treated in any one similar book4 ,if the author has succeeded in making what he has written plain to plain people1 his aim will be fully accomplished4 ,no4 #gc ,broadway1 ,,new ,,york4 ,,contents4 ,,page ,preface iii ,introduction ix ,part ,i4 ,the ,steam ,engine #a ,,ii4 ,the forces of ,air and ,steam #h ,,iii4 ,on ,work1 ,energy and the ,mechanical ,equivalent of ,heat #bb ,,iv4 ,the ,slide-,valve #cj ,v4 ,the ,expansion of ,steam #dg ,,vi4 ,general ,description of a ,locomotive ,engine #fb ,,vii4 ,the ,locomotive ,boiler #ga ,,viii4 ,the ,boiler ,attachments #aae ,,ix4 ,the ,throttle-,valve and ,steam-,pipes #aee ,x4 ,the ,cylinders1 ,pistons1 ,guide-,rods and ,connecting- ,rods #afd ,,xi4 ,the ,valve-,gear #aha ,,xii4 ,the ,running-,gear #bfh ,,xiii4 ,adhesion and ,traction #cai ,,xiv4 ,internal ,disturbing ,forces in the ,locomotive #cbh ,,xv4 ,miscellaneous #cce ,,xvi4 ,screw ,threads1 ,bolts and ,nuts #cda ,,xvii4 ,tenders #cdi ,,xviii4 ,friction and ,lubrication #ceh ,,xix4 ,combustion #cfe ,,xx4 ,the ,resistance of ,trains #djf ,,xxi4 ,proportions of ,locomotives #dab ,,xxii4 ,different ,kinds of ,locomotives #dbg ,,xxiii4 ,continuous ,train ,brakes #ddb ,,xxiv4 ,performance and ,cost of ,operating ,locomotives #ddh ,,xxv4 ,water-,tanks and ,turn-,tables #dea ,,xxvi4 ,inspection of ,locomotives #dfa ,,xxvii4 ,running ,locomotives #dgh ,,xxviii4 ,accidents to ,locomotives #eji ,,xxix4 ,accidents and ,injuries to ,persons #ecc ,,xxx4 ,responsibility and ,qualification of ,locomotive ,runners #edd ,list of ,books for ,mechanics1 ,locomotive ,runners1 ,firemen1 etc41 #eej ,plates #eea ,,appendix4 ,i4 ,table of the ,properties of ,steam #ehe ,,ii4 ,table of ,hyperbolic ,logarithms #eij ,,iii4 ,table of the ,properties of ,different ,kinds of ,fuel #eid ,,iv4 ,table of the ,resistance of ,trains #eif ,index #eih ,,introduction4 ,the ,catechism of the ,locomotive is intended for a large class of readers1 among whom are all kinds of railroad officers and employes1 consisting of locomotive runners1 firemen1 and the many different kinds of mechanics employed in railroad shops and in the construction of locomotive and other kinds of railroad machinery and material4 ,besides these there are many amateur engineers1 students1 and persons interested directly or indirectly in railroads1 and a not inconsiderable class who are always seeking information on all subjects whatsoever4 ,it is evident1 therefore1 that the only way to adapt the book to all the classes for whom it is intended1 was to make it so plain that the 8wayfaring man0 will have no difficulty in comprehending it4 ,it has therefore been written in as clear language as the writer could command1 and the subjects presented are treated as simply and as plainly as his ability enabled him to do1 and with the least possible employment of either scientific or practical technicalities4 ,the only deviation from this plan will be found in the use of algebraic symbols to designate arithmetical calculations4 ,this was done to save space1 and because it was thought that they could be explained so that even those without any knowledge whatsoever of algebra could easily comprehend them4 ,to such as have no such knowledge the following explanation is given3 ,suppose it is necessary to add two numbers1 say #a1hgb and #dfh4 ,the calculation1 if made arithmetically1 would be thus3 #a1hgb #dfh ----- #b1cdj ,this it will be seen occupies the space of several lines of print4 ,if we want to express this calculation algebraically1 it can be done by simply writing the two numbers and placing the sign 1 called plus1 between the two1 which indicates that they are to be added together1 thus3 #a1hgb #dfh ,to indicate what the sum will be1 or what the two added together will amount to1 the sign 1 called equal to1 or the sign of equality1 is placed after the two numbers and between them and the sum1 thus3 #a1hgb #dfh #b1cdj1 which can be read as follows3 #a1hgb added to #dfh is equal to #b1cdj4 ,now the only use of the algebraic signs and is that they save time in writing and room in printing1 and when persons become accustomed to their use they make plain a number of operations at a single glance1 as will be shown hereafter4 ,in the same way that the sign means added to1 the sign - means less or subtracted from1 thus3 #a1hgb - #dfh #a1djd1 which is the same as though it was printed as follows3 #a1hgb less #dfh is equal to #a1djd4 ,the sign means multiplied by1 or is the sign of multiplication4 ,thus3 #a1hgb #dfh #hgf1jif2 that is1 #a1hgb multiplied by #dfh is equal to #hgf1jif4 ,the sign means divided by1 thus3 #a1hgb #dfh #d4 which means3 #a1hgb divided by #dfh is equal to #d4 ,the same thing is expressed by putting a line under the dividend and writing the divisor under the line1 thus3 #a1hgb ----- #d4 #dfh ,these signs are combined in various ways4 ,thus1 supposing we wanted to add #a1hgb to #dfh and then divide the sum by #aag1 it would be necessary1 in order to represent the arithmetical calculation1 to do it as follows3 #ahgb #dfh ---- #aag7bcdj7bj #bcd ---- #j ,algebraically it would be stated thus3 #ahgb #dfh ---------- #bj #aag ,if you wanted to add #abd to the quotient #bj above1 the calculation would be as follows3 #ahgb #dfh ---- #aag7bcdj7 #bj #bcd #abd ---- --- #j #add ,this operation could be expressed by writing it as follows3 #ahgb #dfh ---------- #abd #add4 #aag ,if we wanted to multiply the quotient #bj by #abd we would simply put the sign instead of before #abd1 thus3 #ahgb #dfh ---------- #abd #bdhj4 #aag ,the sign of subtraction or division can be used in the same way4 ,with these explanations it is believed that any one1 with nothing more than an ordinary knowledge of the four elementary rules of arithmetic1 can understand all the mathematics contained in the following pages4 ,a little explanation may also be needed of the method of representing machinery and other structures by mechanical drawings4 ,illustration3 ,a ,b ,c ,d ,if we want to represent the outside of any object1 say an apple1 we make a drawing of it as shown at ,a4 ,now if we want to show the inside of the apple1 say the seeds and core1 we can cut it in half and represent it as shown at ,c1 which is then called a section or sectional view of the apple4 ,if we represent it as it will appear if we are above it and looking down on it as shown at ,b1 it is called a top view or plan4 ,it is evident1 too1 that it might be desirable to show the arrangement of the seeds in the apple as they would appear if it was cut through in the other direction1 say on the line a b1 fig4 ,a1 and as is shown at ,d4 ,there are therefore two kinds of sections2 one ,c1 in which the object is supposed to be cut through vertically1 and therefore called a vertical section1 the other when the object is supposed to be cut through horizontally1 and therefore called a horizontal section1 as shown at ,d4 ,it is also evident that in looking at a locomotive or any other object1 the appearance of the engine depends upon our position in relation to it4 ,thus1 if we stand on the side of it1 we see that part of the engine1 and a drawing which represents the side1 is therefore called a side view or side elevation4 ,a drawing which represents a locomotive or other object as it would appear to us if we stood in front of it1 is called a front view or front elevation1 and a representation of the back part of any object as it would appear to us if we stood behind it is called a back view or back elevation4 ,plate ,i is a side view1 ,plate ,,ii a section1 ,plate ,,iii a top view or plan2#a the vignette in the title page is a front view and fig4 #ga a back view of a locomotive4 ,if the drawing is made as the object would appear if it was turned upside down1 and we were looking at it from above1 then it is called an inverted plan4 #a ,the boiler of the locomotive is supposed to be removed in ,plate ,,iii4 ,it is obvious1 too1 that it is possible to make a great many different sectional views of nearly any object1 especially of a machine4 ,thus1 we could suppose a locomotive cut through vertically and lengthwise1 as is shown in ,plate ,,ii4 ,such a representation is called a longitudinal section4 ,a locomotive could also be cut through crosswise1 as shown in fig4 #dj1 which is called a transverse section4 ,it is of course possible to represent a transverse section of a machine like a locomotive at a great many different points2 for example1 it could be shown as though it was cut through the smoke-stack as in fig4 #dj1 or through the boiler farther back1 as the latter is shown in fig4 #db4 ,usually when a section is shown through a cylindrical object like a smoke-stack or boiler1 it is shown through its centre4 ,if1 however1 this is not apparent from the drawing or engraving1 it should be stated at what point it is supposed to be taken1 thus the section ,d of the apple is on the line a b of fig4 ,a1 and the section ,c is on the line c d4 ,in drawing sections1 the parts which are supposed to be cut in two are usually shaded with parallel diagonal lines drawn at equal distances apart1 as shown in the sections of the apple at ,c and ,d4 ,sections are also sometimes represented with solid black surfaces1 as in ,plates ,,ii and ,,iii1 and in the engraving of a pump in fig4 #ff4 ,objects which are behind others which are in front of them are often shown with dotted lines1 so as to indicate their position4 ,the seeds of the apple are thus indicated at ,a4 ,it is also customary1 in drawings of machinery1 to take great liberties with the objects represented and to show them with parts removed or broken away1 if their construction can thus be made plainer4 ,it should be remembered that the purpose of drawings of this kind is not to give a pictorial representation of the object as it appears to the eye1 but to make its construction and mode of operation apparent to the mind4 ,in such drawings therefore all perspective is disregarded4 ,it would lead us too far were we to explain the reasons for this1 and therefore readers must accept the assertion without the proof4 ,,catechism ,,of ,,the ,,locomotive4 ,,part ,i4 ,,the ,,steam ,,engine4 ,,question #a4 ,what is the motive power employed in ordinary steam engines8 ,answer4 ,the expansive force of steam4 ,,question #b4 ,how is this expansive force of steam applied8 ,illustration3 ,fig4 #a4 ,scale in4 #a foot4 ,a4 ,cylinder4 ,b4 ,piston4 ,r4 ,piston-,rod4 ,d4 ,front ,cylinder-,head4 ,c4 ,back ,cylinder-,head4 ,answer4 ,it is applied by admitting it into a cylinder 7,a1 fig4 #a7 in which a piston1 ,b1 is fitted so as to move air-tight from one end of the cylinder to the other4 ,the steam1 if admitted at ,c1 will force the piston ,b to the opposite end#b of the cylinder4 ,when it has reached that end1 if the steam is allowed to escape and a fresh supply is admitted to the cylinder through the opening d1 it will move the piston back again4 ,in this way1 by alternately admitting steam at one end and exhausting it from the other1 the piston receives a reciprocating motion1 which is communicated to the outside of the cylinder by a rod1 ,r1 which is called the piston-rod1 which works air-tight through an opening in one of the cylinder-covers1 or cylinder-heads1 as they are usually called4 #b ,in all ordinary locomotives1 the cylinders are so placed that the head ,c through which the piston-rod works is behind1 and the other head ,d in front4 ,the two ends of the cylinder are therefore designated the front and back ends1 respectively4 ,illustration3 ,fig4 #b4 ,scale in4 #a foot4 ,a4 ,cylinder4 ,b4 ,piston4 ,r4 ,piston-,rod4 c4 and d4 ,steam-ways4 g4 ,exhaust-,port4 ,v4 ,slide-,valve4 ,h4 ,exhaust-,cavity4 f4f4 ,valve-,seat4 ,i4 ,i4 ,steam-,chest4 ,m4 ,valve-,stem4 r4r4 ,rocker4 ,f4 ,f4 ,fly-,wheel4 s4 ,rocker-,shaft4 ,g4 ,eccentric4 ,k4 ,eccentric-,strap4 ,l4 ,eccentric-,rod4 ,e4 ,connecting-,rod4 ,p4 ,crank4 ,n4 ,crank-,pin4 ,illustration3 ,fig4 #c4 ,illustration3 ,fig4 #d4 c4 and d4 ,steam-,ports4 g4 ,exhaust-,port4 ,illustration3 ,fig4 #e4 ,scale in4 #a foot4 ,,question #c4 ,how is this reciprocating motion of the piston converted into rotary motion8 ,answer4 ,by connecting the end of the piston-rod ,r 7fig4 #b7 by another rod1 ,e2 called a connecting-rod1 with a crank1 ,p1 which is attached to a revolving shaft1 ,s4 ,it is apparent that if the piston ,b is moved in the direction shown by the dart ,r1 a rotary motion will be given to the crank in the direction of the dart ,n4 ,when1 however1 the crank reaches the position shown by the dotted lines in fig4 #e1 it is plain that a force applied to move the piston in either direction will no longer produce a rotary movement of the crank and shaft4 ,the same thing will occur when the crank is in the opposite position1 shown by the full lines4 ,these two positions are called the dead-points of the crank4 ,,question #d4 ,how is the crank of an ordinary steam engine carried past the dead-points8 ,answer4 ,stationary engines are usually provided with a large and heavy wheel1 called a fly-wheel 7,f ,f1 fig4 #b7 which is attached to the shaft ,s4 ,this wheel receives a sufficient amount of momentum from the crank1 while the latter is moving from one dead-point to the other1 to carry it past those points4 ,,question #e4 ,how is the steam admitted to and exhausted from the cylinder8 ,answer4 ,it is admitted through two channels1 c1 d1 fig4 #b1 called steam-ways1 cast in the cylinder4 ,these ways terminate in a smooth flat surface1 f f1 called the valve-seat4 ,their openings in the valve-seat are called steam-ports4 ,between them is another port or cavity1 g1 called the exhaust-port1 which communicates with the open air4 ,the form of these ports is long and narrow1 as shown in fig4 #d1 which represents a plan of them4 ,over these ports a valve1 ,v1 called a slide-valve1 usually made of cast iron1 with a cavity1 ,h1 on its under side1 is fitted so that by moving it backwards or forwards it will alternately cover and uncover the two steam-ports4 ,the valve and valve-seat are inclosed in a sort of box1 ,i ,i1 fig4 #b1 made of cast iron1 called a steam-chest1 into which steam is admitted from the boiler by a pipe1 ,j4 ,when the valve is in the position represented in fig4 #b1 the front steam-port is uncovered and the steam is admitted to the front end of the cylinder1 and thus forces the piston towards the back end4 ,if1 when the piston reaches the back end1 the valve be moved into the position shown in fig4 #c1 the back steam-port will be uncovered and steam will be admitted to that end of the cylinder4 ,at the same time it will be observed that the aperture of the front steam-port c and that of the exhaust-port are both covered by the cavity in the slide-valve1 so that the steam which was admitted to the front end of the cylinder can escape through the steam-port c into the exhaust-port1 and thus into the open air4 ,in this way1 by moving the valve alternately back and forth1 steam is simultaneously admitted first to one end and exhausted from the other1 and vice versa4 ,illustration3 ,fig4 #f4 ,g4 ,eccentric4 ,k4 ,k4 ,eccentric-,strap4 ,l4 ,eccentric-,rod4 ,,question #f4 ,how is the slide-valve moved so as to admit and exhaust the steam at the right time8 ,answer4 ,this is done by what is called an eccentric1 which is a circular disc1 ,g 7fig4 #f71 the axis of which is not in the centre4 ,the outside of the eccentric is embraced by a metal ring1 ,k ,k1 made in two halves1 called an eccentric-strap4 ,the eccentric is attached to the shaft by screws or keys1 and revolves with it and inside of the eccentric-strap4 ,to the latter is also attached a rod1 ,l1 called an eccentric-rod4 ,it is obvious from fig4 #f that if the eccentric revolves inside of the strap it will impart a reciprocating motion to the rod ,l4 ,the eccentric1 ,g1 strap1 ,k1 and rod1 ,l1 are represented in fig4 #b4 ,before describing their operation1 or rather their connection with the valve ,v1 it is necessary to understand that usually the valve-seat is placed on top of the cylinder1 in which position it is difficult to connect the eccentric-rod with the valve4 ,for convenience1 therefore1 what is called a rocker1 r r1 is placed between the cylinder and the main shaft of the engine4 ,this rocker has two arms attached to a shaft1 s1 and the two arms have a vibratory motion about it1 as indicated by the dotted lines4 ,the eccentric-rod ,l is attached by a pin to the lower arm of the rocker1 and the valve is connected to the upper arm by the rod ,m1 called the valve-stem1 or valve-rod4 ,it is obvious that as the shaft ,s and eccentric ,g revolve1 a reciprocating or vibratory motion will be given to the rocker1 which will be communicated to the valve by the valve-stem2 and it is only necessary to fix the eccentric in the proper position on the shaft1 in relation to the crank and piston1 to give the valve the required motion for admitting and exhausting the steam to and from the cylinder at the right time4 ,,part ,,ii4 ,,the ,,forces ,,of ,,air ,,and ,,steam4 ,,question #g4 ,what is meant by the pressure of the air8 ,answer4 ,it is the pressure exerted by the weight of the air on every point with which it is in contact4 ,the globe of the earth is surrounded by a layer of air about #ej miles thick1 and1 like every other substance1 the air possesses weight1 and hence presses upon every object with which it is in contact4 ,,question #h4 ,how can it be shown that the air possesses weight8 ,answer4 ,by weighing a flask when it is filled with air1 and again when the air is exhausted from it4 ,in the latter condition the weight of the flask will be found to be sensibly less than it was when full of air1 showing that the air which the flask contained when it was first weighed increased its weight4 ,,question #i4 ,why do we not feel this pressure on our bodies8 ,answer4 ,because the air surrounds us on all sides1 and presses just as much in one direction as it does in another1 so that the pressures in different directions just balance each other1 or are in equilibrium2 but if you disturb this balance1 for example1 by sucking the air from a tube closed at one end1 it will cling to your tongue2 or if you take a thick piece of leather under ordinary conditions it will not adhere to anything1 but if it be thoroughly wet and pressed hard against the surface of a smooth stone1 so as to force out the air from under it1 the stone1 as nearly all school-boys know1 can be lifted up if a string is attached to the leather2 or if the air be sucked out of a tube1 one end of which is inserted in a liquid1 the latter will be forced up the tube4 ,these phenomena are due to the pressure of the atmosphere in the first case on one side of the person's tongue1 pressing it against the mouth of the tube2 in the second1 to the same pressure on the top of the leather1 causing it to adhere to the stone2 and in the last1 to the weight of the air pressing on the surface of the liquid1 forcing it into the vacuum in the tube4 ,illustration3 ,fig4 #g4 ,scale 4 ,,question #aj4 ,what is the amount of the pressure of the atmosphere1 and how is it measured8 ,answer4 ,it is usually measured by the pressure on one square inch of surface1 which at the earth's surface is #ae pounds4#c ,if1 for example1 we have a cylinder1 ,a1 fig4 #g1 with an air-tight piston1 ,b1 fitted to it whose area is just one square inch1 if we exhaust the air through the tube ,c from the cylinder above the piston1 the air will press against the under side of the piston so that1 if no power is required to overcome its friction in the cylinder1 the pressure of the air will raise a weight of #ae pounds4 ,the pressure of the air varies1 however1 as you ascend or descend from the surface of the earth1 because as you go up on a mountain or in a balloon the layer of air above you becomes thinner1 and1 therefore1 its weight and consequent pressure are diminished2 and as you descend1 as in a deep mine1 the layer is thicker1 and its pressure consequently greater4 #c ,in common practice it is generally taken at #ae lbs4 per square inch1 but the average atmospheric pressure is more accurately #ad4g pounds4 ,,question #aa4 ,what is steam8 ,answer4 ,steam is water changed by means of heat into a gas4 ,at every temperature there is formed from water1 on its surface1 vapor of which the clouds are formed at all seasons of the year4 ,this change of water into vapor1 or evaporation of water1 takes place at low temperatures only on its surface1 however4 ,but if we heat water in a vessel to a temperature of #bab degrees ,fahrenheit1 then the inner particles of the mass of water 7lying on the heating surface of the vessel7 are changed into steam1 and rise to the surface in bubbles1 which is the phenomenon we call boiling4 ,it must not be imagined1 however1 that the visible cloud which escapes from a kettle or the exhaust-pipe of a steam engine is true steam4 ,it is rather small particles of water1 into which the steam has condensed through contact with the cold air4 ,true steam is invisible1 as we may observe near the mouth of a kettle or the exhaust-pipe of an engine from which we know it is escaping4 ,,question #ab4 ,if water is heated in an open vessel what occurs8 ,answer4 ,it continues for some time to increase in temperature1 and the evaporation becomes more and more rapid4 ,at length bubbles of vapor break out and reach the surface1 and the process of boiling or ebullition has begun4 ,when this takes place the temperature of the water ceases to rise1 and it remains stationary until all the water has boiled away1 the only difference being that if the supply of heat be very great the process is very rapid1 and if the supply of heat be small the process is very slow4 ,the point at which ebullition commences is called the boiling-point4 ,,question #ac4 ,on what does the boiling-point depend8 ,answer4 ,chiefly on the pressure on the surface of the water1 but to some extent upon the purity of the water4 ,thus1 boiling1 which takes place at #bab degrees under the ordinary atmospheric pressure1 in lighter air1 as on high mountains1 takes place at a much lower temperature than on lowlands1 and so water boils in a glass tube from which the air has been exhausted by the warmth of the hand1 that is1 at #ib degrees4 ,,question #ad4 ,what is the pressure of steam which escapes from boiling water in an open vessel8 ,answer4 ,it is exactly equal to the pressure of the atmosphere in which it is boiled4 ,ordinarily this is #ae lbs41 and the boiling-point #bab degrees2 but if we go up on a mountain where the atmospheric pressure is only #aj lbs4 per square inch1 the water will then boil at a temperature of #aic4c degrees1 and the steam which escapes will have the same pressure as the atmosphere1 or #aj lbs4 per square inch4 ,on the other hand1 if we could go down into a mine where the atmospheric pressure was #bj lbs4 per square inch1 the water would not boil until it was heated to #bbh degrees1 and the pressure of the escaping steam would then be #bj lbs4 per square inch4 ,,question #ae4 ,if water is boiled in an enclosed vessel like a covered tea-kettle or a steam boiler1 what occurs8 ,answer4 ,the steam rises and fills the space above the water1 and1 if it cannot escape1 increases in pressure4 ,the temperature of both the water and the steam rises with the pressure1 and will continue to do so as long as the heat is increased1 or until the steam can escape or the vessel is exploded4 ,the boiling point also rises as the steam pressure increases4 ,,question #af4 ,is there any pressure which corresponds to the temperature of steam and water8 ,answer4 ,yes4 ,there is a fixed pressure for every temperature1 when steam is in contact with water1 and its pressure cannot be increased or diminished without at the same time heating or cooling the water1 and the higher the temperature of the water the greater will be the corresponding steam pressure4 ,thus water at #bab degrees produces steam with a pressure equal to that of the atmosphere2 at #bdj degrees the steam will have a pressure of #be lbs41 or #aj lbs4 more than the atmospheric pressure2 at #bha degrees a pressure of #ej lbs42 and at #cbh degrees1 #ajj lbs4 ,as this relation of pressure to temperature is fixed1 if we know the one we can tell the other4 ,this is true1 however1 only where the steam is in contact with water1 when it is called saturated steam4 ,if it is separated from water it may be heated to a higher temperature1 and is then called superheated steam4 ,,question #ag4 ,how is the pressure of steam measured8 ,answer4 ,in the same way as that of the atmosphere1--that is1 by the force exerted on one square inch of surface4 ,thus if steam is admitted into the cylinder ,a1 fig4 #h1 under the piston ,b1 whose area is equal to one square inch of surface1 supposing1 as we did before1 that no power is required to overcome its friction in the cylinder1 if the steam thus admitted would just balance the atmosphere1 its pressure would be equal to #ae lbs4 ,if1 besides overcoming the pressure of the atmosphere1 it would raise a weight of #ae lbs41 then its pressure per square inch would be equal to #cj lbs4 ,when the atmospheric pressure is included with that of the steam1 we call it the absolute steam pressure4 ,in ordinary engines1 however1 the steam must always overcome the pressure of the atmosphere1 and therefore the only part of the pressure which is effective is that above1 or by which it exceeds1 the atmospheric pressure4 ,for example1 although the steam admitted under the piston in fig4 #h has an absolute pressure of #cj lbs4 per square inch1 yet it will only raise a weight of #ae lbs41 because it must first overcome the pressure of the air on the other side of the piston4 ,the pressure of the steam used in most stationary and in locomotive engines is1 therefore1 measured by its pressure above the atmosphere4 ,that is1 if steam introduced under the piston in fig4 #h will raise a weight of only #ae lbs41 we say it has a pressure of #ae lbs4 per square inch2 if it will raise #ej lbs41 its pressure is said to be #ej lbs4 per square inch1 and so on4 ,the pressure of the atmosphere is disregarded1 and all steam-gauges used on locomotives are graduated in that way4 ,in speaking of steam pressure in future1 therefore1 unless otherwise specified1 we shall mean effective and not absolute pressure4 ,illustration3 ,fig4 #h4 ,scale 4 ,,question #ah4 ,what is meant by the expansion of steam8 ,answer4 ,in all gases a repulsion is exerted between the various particles1 so that any gas1 however small in quantity1 will always fill the vessel in which it is held4 ,steam possesses this same property1 and if placed in any vessel the particles in endeavoring to separate from each other will exert a force on all its sides4 ,this force we call the steam pressure4 ,to illustrate this we will suppose that the cylinder ,a in fig4 #h is half filled with steam of #cj lbs4 pressure4 ,if now the supply of steam is shut off1 the steam in the cylinder will expand so as to push the piston upward1 but with a somewhat diminishing force1 the nature of which we will explain hereafter4 ,,question #ai4 ,what is meant by the volume of steam8 ,answer4 ,it means the space which the steam occupies4 ,,question #bj4 ,what is the proportion which exists between the volume and the pressure of steam8 ,answer4 ,if the temperatures remain the same they are ,,inversely ,,proportional ,,to ,,each ,,other2 that is1 the one increases in the same proportion as the other diminishes4 ,if we admit steam of #cj lbs4 pressure per square inch into the cylinder ,a1 fig4 #h1 and then cut off the supply by closing the cock ,c and allow the steam in the cylinder to expand to double its volume by pushing the piston to the end of the cylinder1 the steam pressure will then be only #ae lbs42 if it should expand to three times its volume its pressure would be only one-third1 or #aj lbs4 per square inch4 ,this method for calculating the pressure of steam after it has expanded is correct only for the absolute and not for the effective pressures of steam4 ,in order to ascertain the effective pressures of steam after expansion1 it is only necessary to make the calculation with the absolute pressure and deduct the atmospheric pressure from the result4 ,if1 after being thus expanded1 the piston be pushed down again so as to compress the steam into its original space1 its pressure will again be #cj lbs41 providing no heat has been lost in any way4 ,,question #ba4 ,with a cylinder of any given stroke#d how can we determine approximately the pressure of the steam after expansion for any given point of cut-off8#e #d ,the stroke of a piston is the distance it moves in the cylinder1 and in ordinary engines is always twice the length of the crank measured from center to center of the shaft and crank-pin4 #e ,the steam is said to be cut off when the steam-port by which steam is admitted to the cylinder is closed by the valve4 ,answer4 ,,by ,,multiplying ,,the ,,absolute ,,pressure ,,per ,,square ,,inch ,,of ,,the ,,steam ,,in ,,the ,,cylinder ,,before ,,it ,,is ,,cut ,,off1 ,,by ,,the ,,distance ,,from ,,the ,,beginning ,,of ,,the ,,stroke ,,at ,,which ,,it ,,is ,,cut ,,off1 ,,and ,,dividing ,,the ,,product ,,by ,,the ,,whole ,,length ,,of ,,the ,,stroke4 ,thus1 if we have a cylinder whose piston has a stroke of #bd inches1 if we cut off the steam at #h inches1 and have an ,,absolute pressure of #ij lbs4 in the cylinder1 the calculation is as follows3 #ij #h ------ #cj lbs4 final pressure4 #bd ,if we cut off at #aj1 #ab and #ae inches1 the final pressure would be #cg1 #ej and #ef lbs41 respectively4 ,to get the effective pressure deduct the atmospheric pressure from this result4 ,,question #bb4 ,what is the proportion between the volume of steam and that of the water from which it is formed8 ,answer4 ,at the pressure of the atmosphere 7#ae lbs47 each cubic inch of water will make #a1faj cubic inches of steam4 ,at double that pressure1 or #cj lbs4 absolute pressure1 it will make a little more than half as much1 or #hch cubic inches2 at four times1 or #fj lbs4 absolute pressure1 #dcg cubic inches1 or a little more than a fourth as much as at the pressure of the atmosphere4 ,,question #bc4 ,why is it that the quantity of steam at high pressures is somewhat greater than in inverse proportion to the pressure8 ,answer4 ,because the boiling-point of water1 as has already been explained1 is higher as the pressure increases1 and therefore the temperature of the steam produced at such pressure is also higher than at lower pressures2 and as all gases are expanded by heat1 therefore the volume of steam at the higher pressures is somewhat greater than in inverse proportion to its pressure1 on account of being somewhat expanded by its high temperature4 ,to make this plain1 if we take a cubic inch of water and convert it into steam of atmospheric pressure1 its volume will be #a1faj times that of the water1 and its temperature #bab degrees4#f ,if we convert this quantity of water into steam with a pressure double that of the atmosphere1 the volume of the steam will be #hch times that of the water and its temperature will be #bej4d degrees4 ,if the volume of the steam were exactly inversely proportional to the pressure1 the cubic inch of water at double the atmospheric pressure would make only #hje cubic inches of steam2 but as the boiling-point at that pressure is #ch4d degrees higher1 the steam is expanded #cc cubic inches by the increase of its heat due to the higher boiling-point4 #f ,more accurately1 #bac4a degrees1 if we call the atmospheric pressure #ae lbs41 as we have4 ,a table in the appendix gives the pressure1 temperature and volume of saturated steam up to #cjj lbs4 absolute pressure4 ,,question #bd4 ,what is meant by the condensation of steam8 ,answer4 ,it is the reconversion of steam into water by cooling it1 or depriving it of part of its heat4 ,it has been shown that the temperature of water must be raised to a certain point to generate steam of a given pressure4 ,if the process is reversed1 and we deprive the steam of a part of its heat1 some of the steam is then at once reconverted into water1 or condensed1 and the pressure of that which remains will be reduced just in proportion as the heat is lost4 ,when the temperature gets below #bab degrees under atmospheric pressure1 all the steam will be condensed4 ,as the useful work which steam can do in an engine is due to its pressure1 which in turn depends on its temperature1 any loss of heat will diminish its effective power4 ,for this reason1 all waste of heat from a steam engine should1 as far as possible1 be prevented4 ,,question #be4 ,how is the heat of the steam wasted or lost in an ordinary steam engine8 ,answer4 ,it is wasted in three ways3 first1 by conduction2 second1 by convection2 and third1 by radiation4 ,,question #bf4 ,what is meant by these three terms8 ,answer4 #a4 ,by conduction is meant that phenomenon which is manifested when we put one end of a metal bar two or three feet long into the fire and heat it4 ,the heat is then gradually conveyed from one particle of the metal to that next to it until finally the end of the bar farthest from the fire becomes so hot that it cannot be touched4 ,the heat is then said to be conducted through the bar4 ,in the same way the metal of the boiler1 pipes1 cylinders and other parts of the engine becomes heated on one side1 and the heat is thus conveyed to the outside of these parts4 #b4 ,the air with which they are surrounded then becomes heated1 and being then lighter than the cold air1 it rises and is again replaced with air which is not heated4 ,in this way the heat is conveyed away by the air1 and this phenomena is therefore called convection4 #c4 ,if an iron plate be placed in front of an ordinary grate fire three or four feet from it and exposed to the rays of heat from the fire1 it will soon become so hot that you cannot bear your hand on it4 ,if you place your hand between the iron plate and the fire you will find that only the side of your hand which is exposed to the fire will become hot1 showing that the air between the plate and the fire is not nearly so hot as the plate soon becomes1 and therefore that the heat is not conveyed to the plate by the air between it and the fire1 but by the rays from the fire4 ,this phenomenon is called radiation4 ,the same thing occurs from any hot body1 as for example a coil of steam pipe for heating a room1 a steam boiler or cylinder of an engine4 ,,question #bg4 ,is there any difference in the conducting and radiating power of different substances8 ,answer4 ,yes1 very great4 ,the difference in the conducting power of wood and iron is shown if we place one end of a bar of each in the fire4 ,the wood will be consumed without warming the bar more than a few inches from the fire1 whereas the iron will soon become hot two or three feet from the fire4 ,owing to the difference in the conducting power of cotton and wool1 we wear cotton clothing in summer and woolen in winter1 because cotton allows the heat of the body to be conducted away from it1 whereas woolen cloth prevents to a great degree this loss of heat4 ,for the same reason1 the venders of roasted chestnuts on our streets wrap them in a piece of blanket to keep them hot1 that is1 to keep the heat in2 and in summer we wrap ice in the same way to keep it cold1 that is1 keep the warmth of the air out4 ,the wool1 being a very bad conductor of heat1 simply prevents the heat from being transferred from the inside to the outside1 and vice versa4 ,it is for this reason that steam boilers1 pipes and cylinders are nearly always covered with wood1 and sometimes with felt4 ,the difference in the radiating power of various substances can be shown if we take a large thermometer and heat it up to the temperature of boiling water4 ,if this thermometer is hung up in a room having the temperature of melting ice1 it will lose heat in two ways1--first by heating the air which surrounds it1 that is by convection1 and also by radiation4 ,in order to confine ourselves to the latter process1 we will suppose that the chamber is a vacuum4 ,if we first cover the bulb of the thermometer with a thin coating of polished silver1 and then ascertain how much heat it radiates in a minute1 and then coat it with lamp-black1 and repeat the same experiment1--that is to say1 allow the thermometer at the boiling-point to cool for one minute in a vacuum chamber at the freezing-point1--it will be found that the thermometer loses much more in a minute when coated with lamp-black than it did when coated with silver1 showing that much more heat is radiated from a surface covered with lamp-black than from polished silver4 ,generally it may be stated that polished metals radiate much less heat than surfaces which are not polished4#g ,for this reason1 as well as for ornament1 locomotive and other boilers and cylinders are usually covered with ,russia iron or polished brass4 #g ,the account of the above experiment is copied from ,balfour ,stewart's very excellent little book1 8,lessons in ,elementary ,physics10 of which1 and the same author's 8,elementary ,treatise on ,heat10 the writer has made frequent use4 ,,part ,,iii4 ,,on ,,work1 ,,energy1 ,,and ,,the ,,mechanical ,,equivalent ,,of ,,heat4 ,,question #bh4 ,for what purpose are all steam engines used8 ,answer4 ,they are used to produce motion1 which is opposed by some resistance4 ,thus1 if an engine is employed to raise grain from a railroad car to the top of a warehouse1 it must produce motion1 which is resisted by the weight of the grain2 if it is used to saw wood1 it must give motion to the saw1 which is resisted by the fibres of the wood2 a locomotive engine must produce motion of a train of cars1 which is resisted by the air1 the friction of the journals and the rolling of the wheels on the track2 if the locomotive is employed on a grade or incline1 besides the frictional resistance referred to it must overcome that due to its own weight and that of the train1 which is gradually lifted as it ascends the incline4 ,in producing motion opposed by some resistance an engine is said to be doing 8work40 ,,question #bi4 ,can this work be accurately measured8 ,answer4 ,yes2 but in order to measure anything we must first establish some accurate standard or unit of measurement4 ,thus we say a bar of iron is so many inches long1 or a road is so many miles long4 ,in like manner we speak of so many seconds1 or minutes1 or hours1 or days1 or years1 when we speak of time4 ,so it is necessary1 in order to estimate or measure 8work0 in a strictly scientific manner1 for us to fix upon some accurate standard or unit4 ,in this country and in ,great ,britain the unit agreed upon for this purpose is the amount of power required to raise ,,one ,,pound ,,one ,,foot1 and is called a foot-pound4 ,if we raise one pound two feet we do two foot-pounds of work2 if three feet1 three foot-pounds1 and so on4 ,again1 if we raise a weight of two pounds one foot high1 we likewise do two foot-pounds of work2 or if we raise it two feet high1 we do four foot-pounds1 and so on4 ,in order to determine the amount of work done1 we must ,,multiply ,,the ,,motion ,,produced 7in feet7 ,,by ,,the ,,resistance 7in pounds71 ,,and ,,the ,,result ,,will ,,be ,,the ,,work ,,done ,,in ,,foot-,,pounds4 ,,question #cj4 ,how many foot-pounds of work are performed in a pile-driving machine in raising a weight of #a1bjj lbs4 #bd feet8 ,answer4 #a1bjj #bd #bh1hjj foot-pounds4 ,,question #ca4 ,when this weight is raised1 is the force which was exerted in raising it annihilated or lost8 ,answer4 ,no2 because the weight has the capacity of doing an equal amount of work when it falls1 from the momentum#h it acquires in falling4 ,this power of doing work which it acquires in falling is called energy4 ,now1 although the weight has no motion-producing power when it is raised to the top of the machine1 yet obviously such action is then possible which when it rested on the earth was not possible4 ,it has no energy as it hangs there dead and motionless2 but energy is possible to it1 and we might fairly use the term possible energy to express this power of motion which the weight possesses1#i and which is therefore called potential energy4 ,as soon as the weight is allowed to fall it acquires a greater velocity the farther it falls1 and its potential energy thus becomes and is called actual energy4 #h ,momentum is not a very exact term1 but is used here because it ordinarily conveys the idea we wish to express4 #i ,tyndall's 8,heat ,considered as a ,mode of ,motion40 ,,question #cb4 ,how do we explain such phenomena as the heating of a car-axle while turning under a car1 the heating of brake-blocks when the brakes are applied to car-wheels1 the heating of an iron rod by hammering1 and of a turning tool when cutting a piece of metal8 ,answer4 ,all of these phenomena are due to the fact that the actual energy of motion is converted into heat1 as has been repeatedly proved by many able and ingenious investigators and experiments4 ,,question #cc4 ,when the weight of the pile-driver falls1 is its energy also converted into heat8 ,answer4 ,a part is expended in compressing the material into which the pile is driven and in overcoming the friction of the earth against the pile1 each of which efforts develops heat1 and another portion is converted into heat by the impact or blow of the falling weight on the head of the pile4 ,,question #cd4 ,is all energy convertible into heat and heat into energy8 ,answer4 ,yes4 ,science has demonstrated very clearly that they are mutually convertible4 ,,question #ce4 ,has it been ascertained how much heat is equivalent to one foot-pound of work8 ,answer4 ,yes2 it has been found1 from the most carefully-made experiments that the amount of heat which is required to raise the temperature of one pound of liquid water by one degree of ,fahrenheit#aj is equivalent to #ggb foot-pounds of work4 ,it must be remembered that this is the theoretical equivalent of heat1 and that only a very small proportion of this amount of work is ever realized from the heat developed by the combustion of fuel4 #aj ,thermometers are divided into different scales4 ,the one called the ,fahrenheit scale1 after its originator1 is the one ordinarily used in this country4 ,,question #cf4 ,if1 then1 heat is convertible into work and work into heat1 can the transmutation of the heat of the steam in the cylinder of an engine into work1 and the reverse process1 be explained8 ,illustration3 ,fig4 #i4 ,scale in4 #a foot4 ,answer4 ,yes4 ,take a cylinder1 fig4 #i1 and1 in order to make the conditions of the experiment as simple as possible1 imagine it to be placed in a vacuum4 ,now let saturated steam be admitted under the piston so as to fill the cylinder half full at an absolute pressure of #ajj lbs4 ,if we will allow this steam to expand to double its volume and raise the piston without doing any work1 and then repeat the experiment with a load of #ej pounds on the piston1 whose area is one square inch1 it will be found that the temperature of the steam is sensibly less1 after lifting the weight1 than in the previous experiment1 in which it expanded without doing work1 showing that part of the heat was abstracted from the steam by doing work1 or1 in other words1 was converted into work4 ,if then1 after the steam has expanded and lifted the weight1 we press the piston down so that the steam under the piston is compressed to its original volume1 we shall find that its temperature is the same as before1 as the work done in compressing it is converted into heat4 ,in these experiments it is assumed that there is no friction of the piston1 nor loss of heat from radiation or conduction4 ,the same phenomena can be observed in machines used for compressing air1 which is heated to so high a temperature when it is compressed that it is necessary to cool the cylinders of such machines by circulating a current of cold water around them4 ,,question #cg4 ,what practical relation is there between the convertibility of heat into work1 and the conducting and radiating properties of different substances explained in answer to ,question #bg8 ,answer4 ,the fact that heat is only another form of energy1 or 8the power of doing work10 indicates that its loss by conduction or radiation lessens that power just as much as or more than the loss or waste of coal would1 and therefore every effort should be made to protect the different parts of engines from loss of heat by covering them with substances which conduct or radiate very little heat4 ,care should also be taken to exclude cold air from circulating in contact with these parts1 and excepting for supporting combustion1 the nature of which will be explained hereafter1 it should be excluded from the heating surface of boilers4 ,,question #ch4 ,what is meant by the term ,,latent ,,heat ,,of ,,evaporation8 ,answer4 ,by latent heat is meant that heat which apparently disappears when water or other liquids are vaporized4 ,thus1 it is found that if any quantity of water is converted into steam at any pressure1 it is necessary not only to heat it to a temperature equivalent to that of the steam1 or to the boiling-point1 but after it has reached that temperature an additional amount of heat must be added in order to keep up the process of boiling4 ,notwithstanding this addition of heat to the water1 the temperature of the steam produced will not be higher than that of the boiling water1 thus showing that a considerable quantity of heat is absorbed1 the only effect of which is to change the water into a gas or steam4 ,this apparent disappearance of heat can be shown if we take a pound of boiling water whose temperature is #bab degrees and mix it with a pound of ice-cold water at #cb degrees4 ,the result will be a mixture of two pounds of water of a mean temperature of #abb degrees4 ,if now we convert a pound of water into steam at atmospheric pressure1 the steam will heat #f4cg lbs4 of ice-cold water up to #abb degrees1 showing that a pound of steam at atmospheric pressure contains over six times as much heat as a pound of water of the same temperature as indicated by a thermometer4 ,a similar apparent disappearance of heat occurs when other liquids are evaporated1 and when ice or any other solid is converted into a liquid4 ,,question #ci4 ,what is the explanation of these phenomena8 ,answer4 ,the exact reasons which will explain them fully are probably not yet clearly understood1 but it is at least extremely probable that when any substance is changed from a solid to a liquid1 or from a liquid to a gaseous condition1 8a large portion of the heat is spent in doing work against the force of cohesion40#aa ,the particles of solid bodies1 as we know1 are so united that it requires more or less force1 according to the nature of the substance1 to tear them apart4 ,now we can conceive that the heat is changed into a form of energy1 and in that condition resists this attraction of the particles to each other1 and that being thus transformed it has lost the capacity of expanding the mercury in the thermometer4 ,a similar effect takes place when a liquid is converted into a gas4 ,in the former condition the particles move freely about each other and have little or no attraction for each other1 but when it becomes a gas they have a repulsion from each other4 ,the heat is thus converted into the energy of repulsion1 and therefore is in reality no longer in the condition of heat and consequently does not affect the thermometer4 ,we can illustrate this by supposing that by using steam heat is converted into work by raising the weight1 or drop as it is called1 of a pile-driving machine4 ,when the weight is raised to the top of the guides from which it falls1 although1 as already explained1 the heat is converted into potential energy1 yet if we attached a thermometer to the drop we would not find that it was any warmer than before the drop was raised4 ,if it were possible to make an instrument sufficiently sensitive to indicate an instantaneous change of temperature in the weight while falling1 we would not find any increase of its temperature at the instant it had acquired its greatest momentum and just before it struck the object under it1 although its potential energy would at that instant be converted into actual energy of motion4 ,if1 however1 the weight should strike an unyielding object1 its actual energy would at once be reconverted into heat1 which our thermometer would indicate4 ,the phenomenon of what is called latent heat of evaporation seems to be very similar to that described--the heat when the water is changed from a liquid to a gaseous condition is transformed into energy1 which1 as already stated1 has no effect upon the mercury of the thermometer4 #aa ,balfour ,stewart on the ,conservation of ,energy4 ,,question #dj4 ,what is meant by the ,,total ,,heat of steam8 ,answer4 ,the 8total heat of steam0 is a phrase used to denote the sum of the heat required to raise the temperature of water from some given point up to the boiling-point due to a given pressure1 and of the heat which disappears in evaporating one pound of water under a given pressure 7or latent heat of evaporation47 ,thus the latent heat of one pound of steam at atmospheric pressure 7#ad4g lbs47 is #iff4a units2 and #bab units of heat are necessary to raise water from zero to the boiling-point2 therefore the total heat counted from zero of steam of atmospheric pressure is #a1agh4a units4 ,at #ajj pounds absolute pressure the latent heat is #hhe4e and the sensible heat #cbg4i degrees2 therefore the total heat measured from zero is #a1bac4d units4 ,,part ,,iv4 ,,the ,,slide-,,valve4 ,,question #da4 ,what are the essential conditions which a slide-valve must fulfill in governing the admission and exhaust of steam to and from the cylinder of an ordinary engine8 ,answer4 #a4 ,it must admit steam to one end only of the cylinders at one time4 #b4 ,it must allow the steam to escape from one end at least as soon as it is admitted to the other end2 and #c4 it must cover the steam-ports so as not to permit the steam to escape from the steam-chest into the exhaust-port4 ,illustration3 ,fig4 #aj4 ,scale in4 #a inch4 ,,question #db4 ,what was the first form of slide-valve used8 ,answer4 ,that represented in fig4 #aj4 ,the smallest movement of this valve either way opens one of the steam-ports for the admission of steam and puts the other in communication with the exhaust-port4 ,by cutting a piece of ordinary writing paper to the form of the section of the valve1 and moving it on the line f f1 the action of the valve will be clearly shown4 ,illustration3 ,plate ,i4 ,,american ,,locomotive4 ,by ,the ,grant ,locomotive ,works1 ,paterson1 ,new ,jersey4 ,scale1 in4 #a foot4 ,,question #dc4 ,how was the admission and escape of the steam effected by this valve8 ,answer4 ,in order to explain this clearly1 a series of diagrams will be necessary4 ,before referring to them1 however1 it should be explained first that the motion of an eccentric is exactly the same as that of a small crank4 ,it is in fact a crank with a crank-pin whose diameter is very much enlarged4 ,in the diagrams1 figs4 #aa to #be1 the eccentrics will therefore be represented as small cranks1 and most of the other parts by their centre-lines and points only1 so as to make the diagrams as simple as possible4 ,the dimensions selected for these illustrations are for the cylinder #af in4 diameter and #bd in4 stroke1 and a connecting-rod #g ft4 long4 ,the steam-ports are #a in41 the exhaust-port #b in41 and the metal or bars between them1 which are called bridges1 are #a in4 wide4 ,the eccentric produces a lateral movement of #c in41 which is called its throw4 ,in fig4 #aa the piston is at the beginning of the backward stroke4 ,the valve is then in the centre of the valve-face1 and the eccentric is consequently at half-throw4 ,the slightest movement of the crank in the direction of the dart ,n will move the eccentric enough to open the front steam-port to the steam and the back one to the exhaust4 ,in fig4 #ab the piston is represented as having moved #d in4 of its stroke2 the valve has then partly opened the front steam-port1 and the other one is open to the exhaust4 ,in fig4 #ac the piston has moved #h in4 of its stroke1 and the ports are now wide open1 the front one to the steam and the back one to the exhaust4 ,in fig4 #ad the piston has moved #ab in41 or is at half-stroke1 and the valve has then moved as far as it will in that direction4 ,in fig4 #ae the piston has moved #af in4 and the valve has begun to return4 ,in fig4 #af the piston has moved #bj in41 and the valve has nearly closed the front port to the steam and the other to the exhaust4 ,in fig4 #ag the forward stroke is completed1 and both ports are closed by the valve4 ,figs4 #ah1 #ai1 #bj1 #ba1 #bb and #bc represent the piston and the valve on the return stroke in the positions corresponding with those described for the backward stroke4 ,illustration3 ,fig4 #aa4 ,fig4 #ab4 ,fig4 #ac4 ,fig4 #ad4 ,fig4 #ae4 ,fig4 #af4 ,fig4 #ag4 ,scale in4 #a foot4 ,fig4 #bd4 ,fig4 #bc4 ,fig4 #bb4 ,fig4 #ba4 ,fig4 #bj4 ,fig4 #ai4 ,fig4 #ah4 ,scale in4 #a foot4 ,,question #dd4 ,is there any other method by which the motion of a valve can be represented by a drawing8 ,answer4 ,yes1 by what are called motion-curves4 ,it is1 however1 difficult to explain these clearly1 and as they are purely imaginary1 it is difficult to understand their nature and purpose4 ,close attention will therefore be required to the following description3 ,we will suppose1 in the first place1 that the line f f1 fig4 #be1 represents the valve-face1 c and d the steam and g the exhaust-port1 drawn to a larger scale than in the preceding figures4 ,we will now draw the valve ,h in the position represented in fig4 #aa1 where the piston is at the beginning of the stroke4 ,in order to show the valve in the position represented in fig4 #ab1 where the piston has moved #d in4 of the stroke1 we will draw a line #d-bj1 four inches below and parallel to f f1 and extend the lines1 representing the edges of the ports c1 d and g1 downward4 ,on the horizontal line #d-bj we will now draw the edges i1 r1 i1 r1 of the valve in the same position in relation to the port c that it has in fig4 #ab4 ,we will then draw another horizontal line1 #h-af1 eight inches below f f1 and parallel to it1 and on this represent the valve in the position shown in fig4 #ac4 ,in the same way we will draw lines #ab1 #af1 #bj and #bd in4 below f f1 and draw the valve on each one respectively in the positions shown in figs4 #ad1 #ae1 #af and #ag4 ,the distance between the lower line #bd-j1 and f f1 will then represent the stroke of the piston1 or #bd in4 ,if now we begin from the edge h of the valve on the line f f1 and draw a curve1 h i j k l m n1 through the same edge of the valve1 represented on each of the parallel lines below1 the curve will indicate the position of the valve in relation to the steam-port c at each point of the stroke4 ,to illustrate this1 suppose we draw lines #a-bc1 #b-bb1 and #c-ba1 one inch apart and parallel to f f1 and between it and #d-bj4 ,they will then represent the position of the piston after it has moved #a1 #b and #c in4 from the beginning of the stroke1 and where they intersect the curved line will be the position of the edge of the valve when the piston has moved #a1 #b and #c in4 of the stroke4 ,the curved line will in fact represent the position of the valve at any point of the stroke between these lines4 ,other horizontal lines1 #e-ai1 #f-ah1 etc41 can be drawn to represent every inch of the rest of the stroke4 ,the curve line h i j k l m n1 or motion-curve as it is called1 will then show the exact position of the edge of the valve and of the width of the opening of the steam-port during the whole stroke4 ,from it we see that the valve opens the port c for the admission of steam simultaneously with the movement of the piston1 and when the latter has made one inch of its stroke the port c is half open4 ,at #d inches of the stroke the port is wide open1#ab and at #ai inches it begins to be closed1 but is not completely closed until the end of the stroke4 #ab ,by cutting a paper section of the valve and placing it on the diagram in each position named1 it will probably help the reader to understand the movement of the valve more and the nature of the motion-curves4 ,illustration3 ,fig4 #be4 ,scale in4 #a inch4 ,similar motion-curves1 such as h i j k l m n1 7represented in fig4 #be7 can be drawn to represent the position of the other edges of the valve1 and also for the return stroke4 ,the latter are shown in dotted lines4 ,if we follow the curve h i j k l m n1 which represents the position of the edge of the valve h which governs the exhaust from the back end of the cylinder1 we see that the port d is opened and closed to the exhaust simultaneously with the opening and closing of the port c for the admission of steam to the front end of the cylinder1 and that they both remain open until the completion of the stroke4 ,the width that the ports are opened by the valve is thus ascertainable from these diagrams1 for any point of the stroke1 and in fact can be seen at a glance4 ,by the aid of such motion-curves1 the movement of slide-valves can therefore be analyzed more perfectly than is possible without them4 ,,question #de4 ,what were some of the disadvantages of valves1 like that shown in fig4 #aj1 and which are shown by the motion-curves in fig4 #be4 ,answer4 ,the free admission of the steam until the completion of the stroke by the piston was hurtful to the machinery1 as it co-operated with the momentum of the piston and its connections in producing undue strains in the working parts4 ,the steam then escaped from the cylinder without expansion1 so that much of its useful energy was lost4 ,the steam was not allowed to escape from one end of the cylinder until it was admitted at the opposite end1 and as the process of exhausting it occupies some time1 there was always more or less back pressure until all the exhaust steam was expelled from the cylinder4 ,in practice1 the imperfections of the valve-gear frequently delayed the opening of the ports1 both for admitting and exhausting steam1 until after the commencement of the stroke of the piston4#ac #ac ,d4 ,k4 ,clark's 8,railway ,machinery40 ,,question #df4 ,how may some of these evils be overcome8 ,answer4 ,by moving the eccentric forward on the axle so that the motion of the valve is advanced to the same extent1 and the admission and exhaust of the steam will occur a little before the completion of the stroke of the piston4 ,in this way the steam is admitted into the cylinder so as to act as a cushion to receive the momentum of the piston1 and some time is given to the exhaust steam to escape1 before the return stroke4 ,,question #dg4 ,what is meant by lead8 ,answer4 ,by lead is meant the width of the opening of the steam-ports at the beginning of the stroke of the piston4 ,on the steam side of the valve it is called outside lead2 on the exhaust side inside lead4 ,in fig4 #bf the opening h of the steam-port is the outside lead and h the inside lead4 ,illustration3 ,fig4 #bf4 ,scale in4 #a inch4 ,,question #dh4 ,what is meant by the travel of a valve8 ,answer4 ,by the travel we mean the motion of the valve back and forth1 or in other words its stroke4 ,if the arms of the rocker are of the same length1 the travel of the valve is equal to the throw of the eccentric4 ,for the preceding illustrations we have selected an eccentric with three inches throw1 which is the travel of the valve4 ,illustration3 ,fig4 #bg4 ,scale in4 #a inch4 ,,question #di4 ,how is the steam made to work expansively with a slide-valve8 ,answer4 ,by giving the valve what is called lap4 ,that is1 by allowing the edges of the valve when it is in the center of the valve-seat to overlap the edges of the steam-ports1 as shown in fig4 #bg4 ,where this overlap1 ,l ,l1 is on the outside of the valve1 it is called outside lap2 when on the inside1 l l1 inside lap4 ,when a valve has lap1 those portions of the face#ad h1 i1 and h1 q1 which cover the steam-ports1 being wider than the ports1 therefore occupy some time in moving over them1 during which time the steam is enclosed in the end of the cylinder1 as there is then no communication either with the steam-chest or the exhaust-port4 ,this action is shown very clearly by the motion-curves in fig4 #bf4 ,the valve in this case has inch lead4 ,at #d inches of the stroke of the piston the valve has moved as far as it will go in that direction1 and the steam-port has its maximum width of opening4 ,from that point the valve will begin to close the steam-port1 and at #ad inches of the stroke the port will be entirely covered1 and the steam therefore be cut off4 ,the port will remain closed until the piston has moved #ba inches1 when it will be observed from the motion-curve r s t u v w x1 that the port c is opened to the exhaust and the steam escapes1 or1 as it is technically called1 the release takes place4 ,from the time the steam is cut off to the time it is released1 it works expansively in the cylinder4 #ad ,the valve-face is the surface of the valve in contact with the valve-seat4 ,,question #ej4 ,what relation is there between the amount of lap#ae and the degree of expansion8 #ae ,in speaking simply of lap1 outside lap is always meant4 ,answer4 ,the greater the lap with any given travel1 the shorter will be the period of admission of steam1 and1 consequently1 the more time and space for expansion4 ,,question #ea4 ,what is the effect of inside lap8 ,answer4 ,it delays the release of the steam4 ,thus in fig4 #bf the valve has in4 inside lap4 ,the motion-curve r s t u v w x shows that the release takes place during the back stroke at #ba in4 ,if now there was no inside lap1 the dotted line y1 x would represent the exhaust edges of the valve1 and the release would then occur somewhat earlier1 or at #ba in4 ,for this reason no inside lap is usually given to valves for engines which run at high rates of speed1 as it allows too little time for the steam to escape4 ,in fact1 in some cases1 what is called inside clearance is given to the valve2 that is1 the valve as shown in fig4 #bi1 when it is in the middle of the valve-face1 does not entirely cover the steam-ports4 ,the effect of this is just the reverse of that produced by inside lap2 that is1 it causes the release to occur earlier in the stroke4 ,illustration3 ,fig4 #bi4 ,scale in4 #a inch4 ,,question #eb4 ,with the same outside lap1 what is the effect of changing the travel of the valve8 ,answer4 ,by increasing the travel1 the period of admission is increased and that for expansion lessened2 and by reducing it1 the admission is lessened1 and the degree of expansion is increased4 ,this is shown by the motion-curves in fig4 #bh1 in which the same valve and ports are represented as are shown in fig4 #bf1 but the valve has a travel of #e instead of #c inches4 ,the valve also has the same lead4 ,by following the motion-curve h i j k l m n1 it will be seen that the steam is thus admitted up to #bj inches of the stroke of the piston1 and the period of expansion1 as compared with that in fig4 #bf1 is correspondingly lessened4 ,it will also be seen by comparing fig4 #bf with fig4 #bh that with the short travel of the valve the ports are not opened so wide as they are when the travel is increased4 ,this evil is practically obviated1 however1 by making the ports so long that with a comparatively small opening they will still have area sufficient to admit enough steam to fill the cylinders1 and it is known that an opening less than the whole area of the steam-ports is sufficient to facilitate the passage of steam into the cylinder4 ,illustration3 ,fig4 #bh4 ,scale in4 #a inch4 ,,question #ec4 ,how is the exhaust affected by lap and lead8 ,answer4 ,the steam is released earlier in the stroke in proportion as the amount of outside lap and lead is increased1 but the steam-port is also closed to the exhaust1 or compression1 as it is called1 begins earlier with lap and lead than without4 ,thus1 in fig4 #be1 it will be seen that at the beginning of the stroke both ports are entirely closed2 in fig4 #bf1 however1 in which the valve has both lap and lead1 the port d is nearly wide open at the beginning of the stroke1 and by following the motion-curve r s t u v w x1 which represents the position of the exhaust edge of the valve1 it will be seen that the steam was released from the port c before the piston had completed its stroke1 or when it had still nearly #c inches to move4 ,in fig4 #be the port c is not opened to the exhaust until the commencement of the stroke1 but it remains open to its completion1 whereas in fig4 #bf it is closed1 or compression begins1 at #ah inches of the return stroke1 as shown by the dotted motion-curve4 ,,question #ed4 ,how does the action of the connecting-rod influence the motion of the valve in relation to the piston8 ,answer4 ,by delaying the movement of the crank in the backward stroke of the piston1 and accelerating it in the forward stroke4 ,this will be best explained by reference to fig4 #ad1 in which the piston is represented in the center of the cylinder1 or the middle of the backward stroke4 ,if now we take a pair of dividers set to a length equal to that of the connecting-rod1 and from the center1 f1 describe an arc of a circle1 a b1 from the center of the shaft1 and through the lower half of the circle which represents the path of the crank-pin1 we will find that the point of intersection1 a1 falls short of the vertical line1 c d1 and that the crank-pin has not made quite one-quarter of a revolution while the piston was moving through the first half of the backward stroke4 ,by referring to fig4 #ba1 in which the piston is again in the middle of its stroke1 but is moving forward1 and by describing another arc of a circle1 b a1 from the center of the shaft and intersecting the path of the crank-pin1 it will be seen that the latter has moved more than a quarter revolution1 while the piston has made the first half of the forward stroke4 ,owing to this angularity1 as it is called1 of the connecting-rod1 the crank-pin is behind the piston during its backward stroke and ahead of it during the forward stroke4 ,as the valve is moved by the eccentric1 and it in turn by the shaft and crank1 any irregularities of the latter are of course communicated to the valve4 ,we therefore find1 by referring to fig4 #bf1 that the point of cut-off occurs during the backward stroke at #ad inches1 and during the forward stroke at #ab inches4 ,a similar inequality is observable in the points of release for the front and back strokes4 ,it is not1 however1 a matter of very great practical importance with stationary engines which run at comparatively slow speeds2 but if it is thought desirable1 the period of admission and the point of release for both strokes can be equalized1 either by giving the valve more lead or lap at one end than the other1 or by making the one steam-port wider than the other4 ,the mechanism employed for moving locomotive slide-valves1 however1 furnishes us with the means of modifying their motion in relation to that of the piston1 and of thus equalizing the periods of admission and release for the front and back strokes4 ,the methods of doing this will be more fully explained hereafter4 ,,part ,v4 ,,the ,,expansion ,,of ,,steam4 ,illustration3 ,fig4 #cj4 ,scale in4 #a foot4 ,illustration3 ,fig4 #ca4 ,scale in4 #a inch4 ,,question #ee4 ,how can we determine by experiment the pressure of the steam in the cylinder at all points of the stroke8 ,answer4 ,by the use of an instrument made for that purpose1 called an indicator4 ,its action can be best explained by supposing that we have a small cylinder and piston1 ,t1 fig4 #cj1 7shown on an enlarged scale in fig4 #ca7 attached by a pipe ,u to one end of the cylinder ,a1 so that when steam is admitted to the latter it will be conducted to the small cylinder ,t through the pipe ,u4 ,over the small piston and attached to it is a spiral spring1 s s1 fig4 #ca1 which is compressed when the piston rises and extended when it falls4 ,to the top of the piston-rod1 ,v1 a pencil1 ,w1 is attached4 ,behind this pencil we will suppose there is a card1 a b c d1 and that this card is so arranged that we can slide it horizontally and in contact with the pencil point4 ,with only the pressure of the atmosphere above and below the piston ,t1 the spring would be neither compressed nor extended1 and the piston would then stand in the position shown in fig4 #ca4 ,if now we move card horizontally1 the pencil will draw a line1 g1 h1 called the atmospheric line4 ,we will now suppose that the tension of the spring is such that a pressure of #aj lbs4 per square inch above or below the piston will either extend or compress the spring inch4 ,in other words1 every pound of pressure per square inch in the piston will move it of an inch4 ,if we could produce a vacuum under the piston1 it would be pressed down by the atmosphere above it 1 or of an inch4 ,if1 when it is thus depressed1 we again slide the card along in contact with the pencil-point1 it will draw another line1 e1 f1 called the vacuum-line4 ,assuming that we have drawn these two lines1 and that the piston and card are in the position shown in figs4 #cj and #ca1 we will then suppose that a reciprocating motion can be given to the card by the lever ,l1 ,m1 ,n1 fig4 #cj1 which is pivoted at ,m and attached at ,n to the piston-rod by a short connecting-rod4 ,it is obvious that by connecting the upper end ,l of the lever with a rod1 ,l c1 to the card1 the latter will be moved backwards and forwards by the motion of the piston ,b1 and that the motion of the card will be simultaneous with that of the piston ,b1 but of course of shorter stroke4 ,we will assume that the stroke of the card is equal to the length of the atmospheric and vacuum lines g h and e f1 fig4 #ca4 ,if now1 the piston being at the beginning of the stroke as shown in fig4 #cj1 we admit steam of #he lbs4 effective pressure per square inch 7which is equal to #ajj lbs4 absolute pressure7 into the cylinder ,a1 it will be conveyed through the pipe ,u to the cylinder ,t1 and will force up the piston or #b inches above the atmospheric line1 or or #b inches above the vacuum line1 as shown in fig4 #cb1 and the pencil will draw a vertical line1 g i1 on the card1 7represented by a dotted line in fig4 #cb47 ,we will suppose that steam is admitted during #h inches of the stroke1 and is then cut off4 ,when the piston ,b1 fig4 #cj1 has moved that distance1 which is one-third of its stroke1 the card will also have moved one-third of its stroke1 and will stand in relation to the pencil in the position represented in fig4 #cc1 and as the absolute steam pressure in the cylinder was maintained at #ajj lbs4 while the card was moving that distance1 the pencil will have drawn a horizontal line1 i j4 ,the steam is now cut off and begins to expand1 and its pressure is thereby reduced4 ,when the piston of the engine is at half-stroke1 the card will also be at half-stroke1 and the steam will be expanded from #h to #ab inches of the stroke4 ,by the rule given in the answer to question #bj1 its absolute pressure would then be #ff lbs41 and the indicator-piston will then be pressed down by the spring1 so that the pencil will stand in the position shown in fig4 #cd1 or #ff fortieths of an inch above the atmospheric line4 ,the pencil meanwhile will have drawn the curved line j k4 ,when the piston has moved #af inches1 the steam will be expanded to double its volume and its absolute pressure will therefore be #ej lbs41 and consequently the pencil will stand #ej fortieths or #a inch above the atmospheric line as shown in fig4 #ce1 and the pencil will have continued the curve j k to l4 ,at #bj inches the steam will have #dj lbs41 and at the completion of the stroke #cc lbs4 absolute pressure1 and the pencil will have completed the curve j k l m n1 as shown in figs4 #cf and #cg4 ,this curve is called the expansion curve1 and its form is that which mathematicians call a hyperbolic curve4 ,if the steam is exhausted1 the indicator-piston will descend and carry the pencil down to the atmospheric line1 and the vertical line n h1 fig4 #ch1 will be drawn4 ,on the return stroke1 after the steam is exhausted from the main cylinder ,a1 fig4 #cj1 the pencil would draw the atmospheric line g h1 fig4 #ch1 thus showing that there is no steam pressure under the piston4 ,such a diagram is called an indicator diagram4#af ,in practice there are a great many influences which modify it1 such as condensation1 performance of work1 imperfection of valve gear1 etc41 but for the present these are disregarded4 #af ,the indicator used in practice1 to show the action of the steam in the cylinders of steam engines1 differs essentially in its construction from that which we have described4 ,the principles of operation are1 however1 the same in both4 ,we will explain the construction of the ,richard's indicator1 the one which is now most generally used1 hereafter4 ,illustration3 ,fig4 #cb4 ,fig4 #cc4 ,fig4 #cd4 ,fig4 #ce4 ,fig4 #cf4 ,fig4 #cg4 ,fig4 #ch4 ,scale in4 #a inch4 ,,question #ef4 ,how can we ascertain the pressure of the steam for any point of the stroke from such a diagram8 ,answer4 ,by measuring the vertical distance by the expansion curve 7fig4 #ch7 from the vacuum or the atmospheric line1 as for example #h j1 #ab k1 #af l1 #bj m4 ,as the indicator spring is extended or compressed one-fortieth of an inch#ag from every pound of pressure per square inch1 either above or below the indicator piston1 if we construct a scale ,s1 ,s1 fig4 #ch1 with division of one-fortieth of an inch each1 one of them will represent one pound of pressure per square inch if measured vertically from the atmospheric or vacuum line4 ,if we sub-divide the vacuum line with the same number of parts as there are inches in the stroke of the piston 7see fig4 #ci7 we can draw vertical lines from these points and thus determine the pressure by comparing the length of such lines with the scale ,s1 ,s4 ,thus the line #h j measures #ajj fortieths of an inch1 thus showing that the absolute steam pressure at #h inches of the stroke was #ajj lbs4 per square inch2 the line #ab k measures #ff fortieths of an inch1 thus showing that at #ab inches of the stroke the steam pressure was #ff lbs4 ,at #af1 #bj and #bd inches of the stroke the vertical lines measure #ej1 #dj and #cc fortieths2 and therefore there were that number of pounds of steam pressure when the piston was at the point of the stroke named4 ,similar measurements could be made from other points1 such as #b1 #f1 #aj1 or any other number of inches of the stroke4 ,of course1 if we measure from the vacuum line we will have the absolute steam pressure1 or the pressure above a vacuum1 as it is sometimes called2 if we measure from the atmospheric line we will have the effective pressure1 or the pressure above the atmosphere4 #ag ,indicator springs are used of various degrees of tension1 in proportion to the steam pressure to be indicated4 ,illustration3 ,fig4 #ci4 ,scale in4 #a inch4 ,,question #eg4 ,how can we determine the average pressure during the whole stroke of steam which works expansively8 ,answer4 ,this can be determined approximately by the following method3 ,in the first place1 divide the vacuum line 7fig4 #ci7 into any number of equal divisions1 say six4 ,from the points of division1 #d1 #h1 #ab1 #af and #bj1 which in this case correspond with the points which represent inches of the stroke1 draw perpendicular lines1 which will divide the indicator diagram into six divisions4 ,it is obvious that during the time the steam is working full stroke the pressure is uniformly #ajj lbs4 absolute4 ,while the piston is moving from #h to #ab inches the pressure falls from #ajj to #ff lbs41 so that at #aj inches we have very nearly the average pressure during the period named4 ,so from #ab to #af1 #af to #bj and #bj to #bd the average is nearly #eg4a1 #dd4d and #cf4c lbs41 respectively4 ,now1 ,,by ,,adding ,,together ,,the ,,pressures ,,in ,,the ,,middle ,,of ,,each ,,one ,,of ,a ,,number ,,of ,,equal ,,divisions ,,of ,,the ,,stroke ,,and ,,dividing ,,by ,,the ,,number ,,of ,,divisions1 ,,we ,,will ,,obtain ,,approximately ,,the ,,average ,,absolute ,,pressure ,,during ,,the ,,whole ,,stroke4 ,,to ,,get ,,the ,,average ,,effective ,,pressure1 ,,deduct ,,the ,,atmospheric ,,pressure ,,from ,,the ,,result4 ,the calculation would in the above case be as follows3 #ajj lbs4 #ajj #hj #eg4a #dd4d #cf4c ----- #f7dag4h ----- #fi4f ,average absolute pressure4 #ae ----- #ed4f ,average effective pressure4 ,a more accurate way of calculating the average or mean pressure1 as it is called1 when steam is used expansively1 and the one which is usually employed1 is to ,,divide ,,the ,,length ,,of ,,the ,,piston',s ,,stroke ,,in ,,inches ,,by ,,the ,,number ,,of ,,inches ,,at ,,which ,,the ,,steam ,,is ,,cut ,,off3 ,,the ,,quotient ,,is ,,the ,,ratio ,,of ,,expansion4 ,,get ,,the ,,hyperbolic ,,logarithm ,,of ,,the ,,ratio ,,of ,,expansion ,,from ,,the ,,table ,,of ,,logarithms ,,in ,,the ,,appendix1 ,,add #a ,,to ,,it1 ,,and ,,divide ,,the ,,sum ,,by ,,the ,,ratio ,,of ,,expansion ,,and ,,multiply ,,the ,,quotient ,,by ,,the ,,mean ,,absolute ,,steam ,,pressure ,,in ,,the ,,cylinder ,,during ,,its ,,admission4 ,,the ,,result ,,will ,,be ,,the ,,mean ,,absolute ,,pressure ,,during ,,the ,,stroke4 ,,to ,,get ,,the ,,mean ,,effective ,,pressure1 ,,deduct ,,the ,,atmospheric ,,pressure4 ,the calculation for the above example would be as follows3 #bd -- #c ,ratio of expansion4 #h #a4jihf #a ---------- #ajj #fi4ie ,mean absolute pressure4 #c #fi4ie - #ae #ed4ie ,mean effective pressure4 ,the table of hyperbolic logarithms given in the appendix will be needed in calculating the mean pressure of steam used expansively3 ,,question #eh4 ,what advantages result from using steam expansively8 ,answer4 ,there is a very important saving in the amount of steam required to do a given amount of work1 and the strains and shocks which are produced by the rapid motion of the piston and other reciprocating and revolving parts of the engine are very much diminished by allowing the steam to expand1 and thus become reduced in pressure during the latter part of the stroke4 ,,question #ei4 ,how is steam saved by using it expansively8 ,answer4 ,less steam is required when it is used expansively3 #a4 ,because when steam of a high pressure is introduced into the cylinder1 and allowed to expand until its pressure is comparatively low1 it escapes at a lower pressure than the average pressure during the whole stroke4 ,if steam of a pressure equal to the average pressure is worked full stroke1 it would exert exactly the same force on the piston as the steam of higher pressure did when working expansively1 but the pressure in the latter case1 when the piston reaches the end of the stroke1 or the final pressure1 as it is called1 would be considerably lower than in the other4 ,the pressure of steam represents energy1 or capacity for doing work1 and therefore if we allow it to escape with a comparatively high pressure without doing work1 it is a waste of energy4 ,to illustrate this1 we will take the same conditions which were used in the answer to ,question #eg1 in calculating the average pressure4 ,in that case the mean absolute pressure of the steam was #fi4ie pounds per square inch1 but the pressure at the end of the stroke1 when the steam escaped1 was only #cc pounds absolute4 ,if1 therefore1 steam had been used of the average pressure through the whole stroke1 it would have escaped with a pressure of #fi4ie pounds1 or more than twice that of the expanded steam1 and the work done in both cases would have been the same4 #b4 ,there is also another incidental advantage in this1 because low-pressure steam can be exhausted more quickly from a cylinder than steam of a high pressure1 and consequently there is less resistance1 or back pressure1 as it is called1 in the exhausted end of the cylinder to the movement of the piston4 #c4 ,the causes which produce the greatest economy when steam is used expansively cannot be fully explained without discussing principles of science more abstruse than it is desirable to introduce here4 ,they can1 however1 with the aid of the table of the 8,properties of ,steam10#ah in the appendix1 be illustrated by a few simple calculations1 so that the economy of using steam expansively will be apparent4 #ah ,this table is copied from ,colburn's ,treatise on the ,locomotive ,engine4 ,for the basis of the calculations the same data and dimensions will be employed that were used in the previous illustration2 that is1 a cylinder of #af in4 diameter and piston with #bd in4 stroke and steam of #ajj lbs4 absolute pressure cut off at #h in4 of the stroke4 ,we will suppose1 further1 that the steam used is generated from water of a temperature of #fj degrees1 and we will then calculate the total number of units of heat in the steam used for each stroke of the piston4 ,the area of a piston #af in4 in diameter is #bja square inches2 and as the steam is admitted until the piston moves #h inches of its stroke1 therefore the quantity of steam would be #h times #bja cubic inches1 or #afjh #bja #h #afjh cubic in4 ---- cubic ft4 #agbh ,from the table it will be seen that one cubic foot of steam of #ajj lbs4 pressure weighs 4#bcjg lbs42 therefore the weight of the fraction of a cubic foot given above would be calculated as follows3 4#bcjg #afjh ------------ 4#badf lb4 #agbh weight of #afjh cubic in4 of steam of #ajj lbs4 absolute pressure4 ,from the table it will be seen that the total heat above zero of steam of #ajj lbs4 absolute pressure is #abac4d degrees4 ,that is1 as was explained in answer to ,question #dj1ai in order to boil water under a pressure of #ajj lbs4 per square inch we must first heat water up to #cbg4i degrees1 and then1 to convert it into steam1 #hhe4e degrees more must be added4 ,it was also explained in the answer to ,question #ce that one pound of water heated one degree is the standard of measurement or unit of heat4 ,now if we have #a lb4 of water with a temperature of zero1 evidently it will take #abac4d units of heat to convert it into steam of #ajj lbs4 absolute pressure4 ,but as the water from which our steam was generated had a temperature of #fj degrees1 we must deduct that much from #abac4d3 #abac4d - #fj #aaec4d units of heat in one pound of steam of #ajj lbs4 absolute pressure generated from water of #fj degrees temperature4 #ai ,in the illustration used in answer to ,question #dj1 steam of #ajj lbs4 effective pressure was used1 whereas in the above case it is absolute pressure4 ,if now one pound of steam has #aaec4d units of heat1 the following calculation will give the units of heat in 4#badf lbs43 #aaec4d 4#badf #bdg4ea units of heat in 4#badf lbs41 or #afjh cubic in4 of steam of #ajj lbs4 absolute pressure4 ,it was shown in answer to ,question #eg that the average pressure of steam of #ajj lbs4 cut off at #h in4 of the stroke was #fi4ie lbs4 per square inch4 ,disregarding the small fraction1 we will call it #gj lbs4 ,now if we admit steam of this pressure through the whole stroke of the piston1 we will use #d1hbd cubic inches4 ,it will be found by a calculation similar to the above1 that to generate this quantity of steam of #gj lbs4 pressure from water of a temperature of #fj degrees would require #ebg units of heat1 or more than twice as many as were required to do the same work with steam of #ajj lbs4 pressure cut off at #h inches when using it expansively during the rest of the stroke4 ,the actual difference in practice is not so great as this1 because the loss of heat from radiation and condensation in the cylinder and other causes is greater when steam of a high pressure is expanded than when lower pressure steam is admitted through the whole stroke4 ,but after allowance is made for all such sources of loss and waste1 there is still an enormous gain from using steam expansively4 ,,question #fj4 ,what is meant by wire-drawn steam8 ,answer4 ,it is the fall which the pressure of the steam undergoes during its passage from the boiler to the cylinder1#bj and which is due to the contracted opening of the steam pipes or valves4 #bj ,rankine4 ,,question #fa4 ,what is the economical effect of reducing the pressure1 or of wire-drawing it1 by partly closing the valve by which it is admitted to the cylinders8 ,answer4 ,by reducing the pressure of steam in this or any other way1 it is necessary in doing the same amount of work to admit steam to the cylinder for a longer period1 and therefore to reduce the degree of expansion4 ,to illustrate the effect of this1 we will estimate the total heat required to exert a pressure of #gj lbs4 on the piston described above4 ,it will be assumed that the steam pressure in the boiler is #ajj lbs4 absolute1 and that this is wire-drawn down to #gj lbs4 and admitted to the cylinder through the whole stroke4 ,as was shown in the preceding answer1 #d1hbd cubic inches of steam are required to fill the cylinder4 ,now #c1cgf4h cubic inches of steam of #ajj lbs4 pressure1 if expanded to #gj lbs4 pressure1 will make #d1hbd cubic inches4 ,the total heat required to generate #c1cgf4h cubic inches of steam of #ajj lbs4 absolute pressure from water of #fj degrees is #eai4i units1 so that to do the same work by using steam of high pressure cut off at one-third of the stroke1 using steam of low boiler pressure full stroke1 and using wire-drawn steam full stroke1 would1 in the example we have selected1 require #bdg4e1 #ebg and #eai4i units of heat respectively4 ,,question #fb4 ,to what extent can we work steam expansively1 with advantage and economy8 ,answer4 ,the theoretical economy of using steam increases with the degree of expansion and the pressure4 ,this is shown very clearly in the following table1 in the first column of which the number of inches of the piston stroke is given during which steam is admitted to a cylinder #af in4 in diameter and #bd in4 stroke4 ,in the second column is given the pressure of the steam1 or initial pressure1 as it is called1 which must be admitted into the cylinder in order to produce a mean pressure of #gj lbs4 per square inch when it is cut off at the point indicated in the first column4 ,in the third column is given the total heat which is required to generate the steam required in each case1 and in the last column the percentage of saving is given which results from the different degrees of expansion and a mean pressure of #gj lbs4 per square inch in each case4 ,,results ,,of ,,using ,,steam ,,expansively4 ,per- centage ,initial of ,pressure ,total saving of steam heat of compared in pounds steam with ,period of admission or point of per square used1 full cut-off4 inch4 in units4 stroke4 ---------------------------------------- ------------------------- ,full stroke #gj4 #ebg4 #ah in4 ,three-quarters of the stroke1 #gb4e #djh4g #bb #ab in4 ,one-half #hb4g #cji4e #da #h in4 ,one-third #ajj4 #bdg4e #ec #f in4 ,one-quarter #aag4d #bae4i #eh #d in4 ,one-sixth #aej4e #ahf4e #fd #c in4 ,one-eighth #aha4h #afe4h #fh #b in4 ,one-twelfth #bda4d #add4h #gb ---------------------------------------- ------------------------- ,from this table it will be seen that theoretically #bb per cent4 of heat is saved by cutting off at of the stroke and using steam of #gb4e lbs4 pressure instead of steam of #gj lbs4 worked full stroke4 ,cutting off at half stroke and using steam of #hb4g lbs41 #da per cent4 of heat is saved1 and cutting off at quarter stroke with steam of #aag4d lbs4 saves #eh per cent4 of heat2 and at one-twelfth of the stroke1 or expanding steam of #bda4d lbs4 pressure to twelve times its volume1 saves #gb per cent4 of heat4 ,as stated before1 the above is the theoretical advantage of using steam expansively4 ,there are1 however1 practical difficulties in the way of using some of these high degrees of expansion4 ,it has already been explained that if steam is cut off early in the stroke and the degree of expansion increased1 the pressure and consequently the temperature of the steam must also be increased4 ,the danger of explosion is greater with the higher pressures1 and stronger and more expensive boilers and machinery are therefore needed4 ,with steam of very high temperature the metal of the cylinders1 pistons and valves becomes so much heated that they soften1 and then the friction of the one on the other causes them to cut or scratch each other4 ,the high temperature at the same time destroys the oil or other lubricant used in contact with the steam4 ,it is also impossible to admit and cut off steam very early in the stroke with the ordinary mechanical appliances used for moving slide-valves of locomotives4 ,this latter difficulty will be more fully explained hereafter4 ,,part ,,vi4 ,,general ,,description ,,of ,a ,,locomotive ,,engine4 ,,question #fc4 ,what are the principal parts of an ordinary locomotive engine8 ,answer4 ,a boiler for generating steam and a pair of high-pressure steam engines1 which are all mounted on a suitable frame and wheels adapted for running on a track consisting of two iron or steel rails4 ,,question #fd4 ,how is the power of high-pressure engines applied to locomotives8 ,answer4 ,by connecting the engines with the wheels so as to give the latter a rotary motion4 ,,question #fe4 ,when they revolve what will occur8 ,answer4 ,either they will slip on the track1 or the locomotive will move either backward or forward1 according to the direction the wheels are turning4 ,,question #ff4 ,what will determine whether the wheels will slip or the locomotive move8 ,answer4 ,the friction or adhesion1 as it is called1 between the wheels and the track4 ,if this adhesion is greater than the resistance opposed to the movement of the locomotive1 the latter will overcome the resistance2 but if the latter is greater than the friction1 the wheels will slip4 ,,question #fg4 ,upon what does the amount of friction or adhesion of the wheels depend8 ,answer4 ,chiefly on the weight which they bear1 but to some extent upon the condition of the rails4 ,under ordinary circumstances1 the adhesion of the wheels of a locomotive is in direct proportion to the weight they carry4 ,,question #fh4 ,why are two cylinders employed on locomotives8 ,answer4 ,because if only one was used1 it would be impossible or very difficult to start the engine1 if it should stop on one of the dead points4 ,,question #fi4 ,how is this difficulty overcome by the use of two cylinders8 ,answer4 ,by attaching the two cranks to the same shaft or axle1 and placing them at right angles to each other1 so that when the one is at a dead point the other is in the position where the steam can exert the maximum power on the crank4 ,,question #gj4 ,how are the cranks of an ordinary locomotive made8 ,answer4 ,they are cast in one piece with the wheels that drive the locomotive1 which are therefore called driving-wheels4 ,in this country the centre portion of such wheels1 or wheel-centres as they are called1 is always made of cast iron1 with tires of wrought iron or steel around the outside1 and is fastened to the axles of the locomotive4 ,the shaft of a locomotive engine is called the main driving-axle1 and the wheels attached to it the main driving-wheels4 ,,question #ga4 ,how are the cylinders and driving-wheels of a locomotive usually placed8 ,answer4 ,the cylinders ,a1 plates ,i1 ,,ii and ,,iii1 are placed at the front end of the locomotive1 and the main driving-axle1 ,b1 far enough behind them to permit the connecting rods1 ,c1 to be attached to pins1 ,d1 in the cranks1 called crank-pins4 ,in this country these cranks are now universally placed on the outside of the wheels1 and therefore the cylinders must be placed far enough apart 7as shown in fig4 #dj and ,plate ,,iii7 to permit the connecting-rods to be attached to the crank-pins4 ,the cylinders are therefore placed outside the frames1 ,h1 ,h1 ,plate ,,iii1 7the latter are inside of the wheels17 and are now nearly always horizontal1 although in old engines they are often inclined4 ,plate ,i is a side view of an ordinary eight-wheeled ,american locomotive1 ,plate ,,ii a longitudinal section1 ,plate ,,iii a plan1 and fig4 #dj1 a transverse section through the cylinder and smoke-box4 ,illustration3 ,fig4 #dj4 ,scale in4 #a foot4 ,,question #gb4 ,what are the smaller wheels1 ,e ,e1 called1 and what are they for8 ,answer4 ,they are called truck-wheels and carry the weight of the cylinders and other parts of the front end of the locomotive1 and serve to guide and steady the machine in a manner which will be more fully explained hereafter4 ,,question #gc4 ,why are more than one pair of driving wheels necessary for locomotives8 ,answer4 ,because if all the weight which is needed to create the requisite adhesion of the wheels of locomotives to pull heavy loads was placed on one pair of wheels1 it would be so excessive as to partly crush and injure the rails4 ,it is therefore distributed1 usually on two pairs1 but sometimes on three or four or even more pairs4 ,,question #gd4 ,where is the second pair of driving-wheels usually placed8 ,answer4 ,these wheels1 ,f--called the back or trailing driving-wheels--are1 in the ordinary type of locomotives used in this country1 situated behind the main driving-wheels1 far enough back to give the room necessary for the boiler1 ,g1 between the two axles1 as shown in plates ,i1 ,,ii and ,,iii4 ,,question #ge4 ,how are the axles1 cylinders1 etc41 held in the right position in relation to each other8 ,answer4 ,by longitudinal frames1 ,h1 ,h1 ,h1 ,h1 which hold the axles in the proper position1 and are bolted to the cylinders1 and also fastened to the boiler at ,i1 ,i1 ,plate ,i4 ,,question #gf4 ,how is a locomotive engine made to run either backward or forward8 ,answer4 ,by having two eccentrics1 ,j1 ,j1 ,plate ,,iii 7also shown in ,plate ,,ii17 for each cylinder4 ,one of these is fixed or set on the shaft in such a position as to move the valve so that the engine will run in one direction2 the other eccentric is set so that the engine will run the reverse way4 ,the ends of the two eccentric rods are attached to what is called a link1 ,l1 7,plates ,,ii and ,,iii17 the object of which is to furnish the means of quickly engaging and disengaging either eccentric rod to or from the rocker1 ,k4 ,the link is operated by a system of levers1 consisting of the lifting shaft1 ,m1 and arms1 ,n1 ,n1 and the reverse lever1 ,o1 ,o1 7,plate ,,ii74 ,the principles and working of these will be more fully explained hereafter4 ,,question #gg4 ,what are the principal parts or 8organs0 of a locomotive boiler8 ,answer4 #a4 ,a fire-place1 or1 as it is called a fire-box1 ,g1 7,plate ,,ii17 which is surrounded with water4 #b4 ,a cylindrical part1 ,p ,p1 7,plates ,i and ,,ii17 attached to the fire-box at one end and to a chamber1 ,q1 called the smoke-box1 at the other4 #c4 ,the tubes or flues a a1 7,plate ,,ii and fig4 #dj17 which connect the fire-box with the smoke-box and pass through the cylindrical part of the boiler and are surrounded with water4 #d4 ,the smoke-stack or chimney ,r ,r4 ,,question #gh4 ,what is each of these parts or organs for and of what do they consist8 ,answer4 ,the fire-box ,g furnishes the room for burning the fuel1 and consists of an inner and outer shell made of boiler plate1 with the space between the two filled with water2 a grate1 b b1 7,plate ,,ii17 formed of cast-iron bars1 with spaces between them for admitting air for the combustion of the fuel1 which is placed on the top of them2 a door1 ,c1 called the furnace-door1 for supplying the grate with fuel2 a receptacle1 d d1 below the grate1 to collect ashes1 and therefore called the ash-pan1 which is supplied with suitable dampers1 n1 n1 for admitting or excluding the air from the fire4 ,the cylindrical part ,p ,p1 or waist of the boiler as it is sometimes called1 contains the greater part of the water to be heated4 ,the flues or tubes1 as they are generally called1 of which a locomotive has from one to two hundred1 are usually two inches in diameter1 and about eleven feet long4 ,they conduct the smoke and products of combustion from the fire-box to the smoke-box4 ,these tubes are made of small diameter so as to sub-divide the smoke into many small streams and thus expose it to a large radiating surface through which the heat is conducted to the water4 ,the smoke-stack serves partly for removing into the open air the smoke which passes through the flues1 and partly for producing a strong draft of air1 which is indispensably necessary for the rapid combustion of the fuel1 and also for collecting and extinguishing the sparks from the fire4 ,,question #gi4 ,how is the draft produced in locomotive boilers8 ,answer4 ,by conducting the exhaust steam through pipes 7e1 e1 fig4 #dj7 from the cylinders to the smoke-box and allowing it to escape up the smoke-stack from apertures1 f1 f1 7,plate ,,ii1 fig4 #dj47 called exhaust nozzles4 ,the strong current of steam thus produced in the smoke-stack produces a vacuum1 by which the smoke is sucked into the smoke-box with great power and forced out of the smoke-stack into the open air4 ,,question #hj4 ,how are the water and fuel carried which must be supplied to a locomotive while it is running8 ,answer4 ,the water is carried in a tank1 which is constructed in the form of the letter ,u1 so as to give room for the stowage of fuel between its two branches or sides4 ,this tank is carried on a set of wheels1 and forms a separate vehicle1 independent of the locomotive1 called a tender1 the construction of which will be explained in a future chapter4 ,,question #ha4 ,what are the dimensions of the principal parts of a locomotive8 ,answer4 ,there is a great variety in the plan1 size and capacity of locomotives1 but the type which is more generally used in this country than any other1 and which has been selected for the preceding illustrations1 and will be described in the succeeding chapters of the ,catechism1 has four driving and four truck wheels1 and weighs in working condition about #fj1jjj lbs4 ,the following are the dimensions of its principal parts3 ,the driving-wheels are about #e feet and the truck-wheels from #bf to #cj inches in diameter4 ,the longitudinal distance between the centres of the driving-wheels is usually about #g feet1 and between the centres of the truck-wheels #e ft4 #i in41 and the total distance from the centre of the back driving-wheels to the centre of the front truck-wheels1 which is called the wheel-base1 is #ba ft4 #h in4 ,the weight on each driving-wheel is usually about #aj1jjj lbs41 and on each truck-wheel about #e1jjj lbs4 ,the cylinders are #af in4 in diameter and the piston has #bd in4 stroke1 and the connecting-rod is #g ft4 long measured between the centres of the pins to which it is attached4 ,the centres of the cylinders are about #f feet apart1 measured across the track4 ,the fire-box inside is #e feet long and #b ft4 #aa in4 wide1 and the cylindrical part of the boiler is #d feet in diameter measured on the outside of the smallest portion4 ,the water spaces around the fire-box are about #c inches wide4 ,there are #adj tubes1 which are #b in4 in diameter measured on their outside1 and #aa ft4 long4 ,the inside of the smoke-stack is #af in4 in diameter1 and it is #ad ft4 #c in4 high measured from the top of the rails4 ,the tender carries about #a1hjj gallons of water and about #h1jjj lbs4 of coal4 ,when loaded it weighs about #dj1jjj lbs41 making the total weight of the engine and tender #ajj1jjj lbs4 ,the following is a list of parts designated by the letters of reference on plates ,i1 ,,ii1 ,,iii and fig4 #dj4 ,a1 ,a1 ,cylinders4 ,b1 ,main driving-axle4 ,c ,c1 ,main connecting-rods4 ,d ,d1 ,main crank-pins4 ,e1 ,e1 ,truck-wheels4 ,f1 ,axle of trailing-wheels4 ,g1 ,fire-box4 ,h1 ,h1 ,h1 ,frames4 ,i1 ,i1 ,frame-clamps4 ,j1 ,j1 ,eccentrics4 ,k1 ,k1 ,rockers4 ,l ,l1 ,links4 ,m1 ,lifting-shaft4 ,n1 ,n1 ,lifting arms4 ,o ,o1 ,reverse-lever4 ,p ,p1 ,cylinder part of boiler4 ,q1 ,smoke-box4 ,r ,r1 ,smoke stack or chimney4 ,s1 ,pilot or cow-catcher4 ,t1 ,head-light4 ,u1 ,bell4 ,v1 ,sand-box4 ,w1 ,whistle4 ,x1 ,dome4 ,y ,y1 ,cab or house4 ,z1 ,back or trailing-wheel crank-pin4 ,a1 ,pump air-chamber4 ,b1 ,b1 ,main driving-wheels4 ,c ,c ,c1 ,supply-pipe4 ,d1 ,front platform4 ,e1 ,bumper timber4 ,f ,f1 ,back driving-wheels4 ,g1 ,coupling-pin4 ,h1 ,friction-plate4 ,i1 ,check-valve4 ,k ,k1 ,foot-board4 ,l1 ,lazy cock4 ,m1 ,mud drum4 ,n ,n1 ,driving springs4 ,p1 ,pump4 ,r1 ,drop-door or grate4 ,s1 ,steam gauge4 ,t ,t1 ,feed pipe4 ,u ,u1 ,forward eccentric rods4 ,v ,v1 ,backward eccentric rods4 ,x1 ,lifting-shaft spring4 ,y ,y1 ,dampers4 ,z1 ,pushing-bar4 a a1 ,tubes4 b b1 ,grate4 c1 ,fire-box door4 d d1 ,ash pan4 f f1 ,exhaust-nozzles or blast-pipes4 g1 ,safety-valve lever4 h h1 ,cross-heads4 i i1 ,running-board4 j1 ,throttle-stem4 l1 ,throttle-pipe4 m m1 ,dry pipe4 n1 ,t-pipe4 o o1 ,steam-pipe4 p1 ,petticoat pipe4 q1 ,smoke-box door4 r1 ,piston4 s1 ,spark-deflector or cone4 t t1 ,wire-netting in stack4 u u u1 ,boiler-lagging4 v v1 ,truck-spring4 w w1 ,sector or quadrant4 x1 ,blow-off cock4 e k1 ,reversing-rod4 y1 ,truck centre-pin4 z1 ,throttle-lever4 a a1 ,tubes4 b b1 ,truck frame4 c c1 ,bed-plate4 d1 ,boiler brace4 e e1 ,sand pipe4 f f1 ,equalizing lever for driving wheels4 g g1 ,guide-bars or rods4 h h1 ,receptacle for sparks4 i i1 ,bell rope4 j j1 ,guide yoke4 k1 ,valve-stem4 l l1 ,truck equalizing lever4 m m m1 ,hand-rail4 n1 ,blow-off cock in mud drum4 o1 ,spring balance4 p1 ,pump plunger4 q q1 ,foot steps4 r1 ,brace to smoke-box and frame4 s s1 ,steam-chests4 t t t1 ,crown-bars4 u1 ,head-light lamp4 v1 ,main valve4 w1 ,blow-off cock handle4 x1 ,bell-crank for throttle-valve4 y1 ,piston-rod4 z1 ,draw-bar4 ,,part ,,vii4 ,,the ,,locomotive ,,boiler4 ,,question #hb4 ,how does the quantity of steam generated in locomotive boilers in a given time compare with that generated in the boilers of stationary and marine engines8 ,answer4 ,locomotive engine boilers must produce much more steam in a given time1 in proportion to their size1 than is required of the boilers of any other class of engines1 7excepting perhaps those of steam fire-engines17 because the space which locomotive boilers can occupy and also their weight is limited4 ,,question #hc4 ,how is their steam-generating capacity increased above that of marine and stationary boilers8 ,answer4 ,by creating a very strong draft of air through the fire and then passing the smoke and heated air through a great many small tubes1 which are surrounded by water4 ,by this means the smoke and hot air are divided into many small streams or currents which are exposed to the inside surface of the tubes to which and to the surrounding water their heat is imparted4 ,,question #hd4 ,how is the action of the exhaust steam in producing a draft in the chimney explained8 ,answer4 ,the exhaust steam escapes from the cylinders through one or two contracted openings or exhaust-nozzles 7f1 ,plate ,,ii1 also shown in fig4 #djba71 which point directly up the centre of the chimney or smoke-stack4 ,the exhaust steam escapes from this orifice with great velocity1 and expands as it rises1 so that it fills the pipe p and the smoke-stack ,r ,r4 ,it thus acts somewhat like a plunger or piston forced violently up the chimney1 and pushes up the air above it1 and1 owing to the friction of the particles of air1 carries that which surrounds it along up the stack1 from which it all escapes finally into the open air1 thus leaving a partial vacuum behind in the smoke-box4 ,the external pressure of the atmosphere then forces in air through any and every opening in the smoke-box1 to take the place of that already drawn out or exhausted from it4 ,as the only inlet is through the tubes1 to which the gases of combustion have free access from the fire-box1 and as the external air can only pass through the fire-grate1 and through the burning fuel1 to reach the fire-box1 there is a constant draft of air through the grate as long as the waste steam escapes from the blast-pipe and up the chimney4 ,it is thus that1 within certain limits1 the more the steam that is required1 the more the steam that is produced2 for all the steam used in the engine draws in the air in its final escape1 to excite the fire to generate more steam4#bb ,sometimes one blast-orifice is used for each cylinder1 as shown in plates ,,ii and ,,iii and fig4 #dj2 in other cases the exhaust steam from each cylinder escapes through the same orifice4 #ba ,the term blast-orifice is also often used to designate these parts of locomotives4 #bb ,colburn's ,locomotive ,engineering4 ,,question #he4 ,how much water is it necessary to evaporate in order to furnish the steam required to run an ordinary train at its usual speed8 ,answer4 ,for an ordinary 8,american0 locomotive1#bc weighing #fj1jjj lbs4 and with cylinders of #af inches diameter and #bd inches stroke1 from #f1jjj to #ab1jjj lbs4 of water must be evaporated per hour4 #bc ,in speaking of 8,american0 locomotives1 we mean locomotives like that shown in ,plate ,i1 with four driving-wheels and a four-wheeled truck1 and shall so use the term hereafter4 ,,question #hf4 ,how much water will a pound of coal evaporate in ordinary practice8 ,answer4 ,the quantity of water which is converted into steam by a pound of coal varies very materially with the quality of the coal1 and the construction and condition of the boiler2 but from #f to #h lbs4 of water per pound of coal is about the average performance of ordinary locomotives4 ,it is1 therefore1 necessary to burn from #ejj to #b1jjj lbs4 of coal per hour in order to generate the quantity of steam required by ordinary engines4 ,,question #hg4 ,how large a grate is needed to burn this quantity of coal8 ,answer4 ,the maximum rate of combustion may be taken at about #abe lbs4 of coal on each square foot of grate surface per hour1 so that to burn #b1jjj lbs4 we need a grate with about #af square feet of surface4 ,,question #hh4 ,how much heating surface is needed for a given size of grate8 ,answer4 ,in common practice about #ej square feet of heating surface are given for each square foot of grate4 ,there are1 however1 no reasons for the proportions of either grate or heating surface which are given1 excepting that it has been found that they work well in practice4 ,it is1 however1 quite certain that the larger a boiler is1 and the greater its heating surface in proportion to the steam it must generate1 other things being equal1 the more economical will it be in its consumption of fuel1 or1 in other words1 the more water will it evaporate per pound of coal4 ,,question #hi4 ,why is it necessary to use small tubes or flues in order to have the required amount of heating surface8 ,answer4 ,because there is a great deal more surface in a small tube of a given length1 in proportion to the space it occupies1 than in a large one4 ,thus a tube two inches in diameter and eleven feet long has #hbi square inches of surface1 and one four inches in diameter has #a1feh square inches1 or just double the quantity4 ,but the four-inch tube occupies four times as much space as the other1 as it is twice as high and twice as wide4 ,therefore1 in proportion to the space it occupies1 the tube which is two inches in diameter has twice as much surface as the larger one4 ,if we compare a two-inch with an eight-inch tube1 we will find that the former has four times as much surface1 in proportion to its size1 as the eight-inch tube4 ,as the size and weight of locomotive boilers are limited1 it is therefore necessary1 in order to get the requisite heating surface in the space to which we are confined1 to use tubes of small diameter4 ,small tubes also have the advantage that they may be made of thinner material1 and yet have the same strength to resist a bursting pressure from within1 or a collapsing pressure from without1 as larger tubes made of thicker metal4 ,the advantage of thin tubes is1 that the heat inside of them is conducted to the water outside more rapidly than it would be through thicker metal1 which is important when combustion is as rapid as it is in locomotive boilers4 ,the reason tubes of smaller diameter than two inches are not ordinarily used is because they are then liable to become stopped up with cinders and pieces of unconsumed fuel4 ,,question #ij4 ,how is the fire-box of a locomotive constructed8 ,answer4 ,it usually consists of a rectangular box 7,g1 figs4 #da and #db7 about three feet wide#bd and1 for the size of engine we have selected as an example1 about five or five and a half feet long inside4 ,this box is composed of metal plates1 either iron1 steel or copper1 which1 excepting on the front side1 are from to of an inch thick4 ,this box is called the inside shell of the fire-box1 and is surrounded by another shell1 ,a ,b ,c ,d ,e ,f1 fig4 #db1 of either iron or steel plates1 of about the same thickness as those composing the inside4 ,this is called the outside shell of the fire-box and1 as already explained1 is so much larger than the inside that there is a space1 called the water-space1 from #b to #d inches wide1 on all the sides of the fire-box between the inner and outer plates4 #bd ,the width is dependent upon the distance between the rails1 or gauge of the road1 as it is called4 ,the above size is for a #d feet #h in4 gauge4 ,the top g1 g1 of the inside shell1 which is called the crown-sheet or crown-plate1 is flat1 whereas the outside shell is arched1 as shown in fig4 #db4 ,to the front plate of the inside shell the tubes a a1 a a are attached4 ,for this reason its thickness is usually made greater than that of the other plates1 and is usually from to of an inch4 ,the edges of one of the plates at each corner of the fire-box1 where they are united together1 as shown in figs4 #da and #db1 are bent at right angles1 and the other is fastened to it with rivets from to of an inch in diameter4 ,the inside and the outside shells of the fire-box are united to each other by a wrought-iron bar or ring 7,a ,f1 figs4 #da and #db7 which completely surrounds the inner shell and closes the water-space between the two shells4 ,this bar is bent and welded to the proper form to extend around the bottom of the inside fire-box1 and it is riveted to both shells4 ,the water in the water-space is in free communication with the rest of the water in the boiler2 and thus the flat sides of the respective shells of the fire-box are exposed to the full pressure of the steam1 which tends to burst the outside shell and collapse the inside one4 ,these flat sides1 by themselves1 would be unable to resist the strain upon them1 but as the strain upon the respective fire-boxes is in opposite directions1 and necessarily equal for equal areas of surface1 tie-bolts1 n1 n1 n1 n1 7figs4 #da and #db17 or1 as they are called stay-bolts1 which are from to #a inch in diameter1 are screwed through the plates at frequent intervals1 usually from #c to #d in4 apart1 so as to connect the two fire-boxes securely together1 the ends of the stay-bolts being also riveted or spread out by hammering so as still further to increase their holding power4 ,these bolts1 owing to the expansion and contraction of the boiler and other strains to which they are subjected1 very frequently break1 and if they are made of solid bars of metal there is no way of discovering with certainty whether they are in good condition or not without taking the boiler to pieces4 ,they should therefore be made of the best quality of wrought iron1 brass or copper and should also be made tubular1 that is they should have a hole through the centre1 so that when they break the water will escape at the fracture into the hole and the leak will thus indicate the defect and danger4 ,the latter is much greater from this cause than is usually supposed1 and it is not unusual to find on taking a boiler to pieces that a large number of the stay-bolts are broken4 ,illustration3 ,fig4 #da4 ,scale in4 #a foot4 ,illustration3 ,fig4 #db4 ,scale in4 #a foot4 ,,question #ia4 ,how can the strain on the flat surface of a boiler between the stay-bolts be calculated8 ,answer4 ,by ,,multiplying ,,the ,,area ,,in ,,inches ,,between ,,adjacent ,,stay-,,bolts ,,by ,,the ,,pressure4 ,the reason for this is1 that each stay-bolt must sustain the pressure on a part of the plate to which it is attached4 ,thus in fig4 #dc it is plain that the bolt s must sustain the pressure on one-half of that part of the plate between it and the bolts v1 t1 w1 u1 around it1 or the pressure on the square a b d c1 whose sides are equal to the distance 7#d inches7 between the centres of the bolts4 ,with a pressure of #ajj pounds per square inch1 the calculation would therefore be3 #d #d #ajj #a1fjj lbs4 on each bolt4 ,illustration3 ,fig4 #dc4 ,scale #a in4 #a foot4 ,stay-bolts should never be subjected to a strain of more than one-eighth or one-tenth of their breaking strength4 ,,question #ib4 ,how do stay-bolts often fail without breaking8 ,answer4 ,by tearing or stripping the thread of the bolt1 or that in the plate1 but oftener perhaps by the stretching of the plates between the holes4 ,with a heavy pressure1 the tendency of the plates between the holes1 especially if they are heated very hot1 is to 8bulge0 outward and thus stretch the hole in every direction until it is so large that the bolt is drawn out without much injury to the screw-thread4 ,,question #ic4 ,how is the flat-top or crown-sheet strengthened8 ,answer4 ,it is sometimes strengthened with stay-bolts similar to those used for the sides1 which pass through the inner and outer shells2#be but usually the crown-sheet is strengthened by a series of iron bars1 7f1 f1 fig4 #da and #db7 called crown-bars1 placed on edge1 and of considerable depth1 which are firmly fastened to it by ,t-head rivets or bolts4 ,the crown-sheet can therefore only be crushed downwards by bending these bars1 which are of great strength4 ,they usually extend crosswise of the length of the fire-box1 but are sometimes placed lengthwise4 ,these bars bear on the fire-box only at each end1 as shown in fig4 #db1 and are usually made with a projection1 k1 k1 which rests on the edge of the side plates4 ,iron rings or washers from to #a inches thick are interposed between the plate and the bars at the points where the bolts or rivets which secure the rivets pass through4 ,this permits the water to circulate under the bars1 and prevents the crown-sheet from being burnt or overheated1 as it would be if the water were excluded from the whole under surface of the crown-bars4 #bf,the crown-bars are also attached to the outer shell and the dome by braces1 e1 e1 l1 l4 #be ,this method of staying crown-sheets has been extensively used on the ,baltimore ,ohio and ,reading railroads1 and is now very generally used in ,europe4 #bf ,colburn's ,locomotive ,engineering4 ,the opening c1 fig4 #da1 at the back end is for the door through which fuel is supplied to the grate4 ,,question #id4 ,how are the grates constructed8 ,answer4 ,they are generally made of cast-iron bars1 and for burning coal are usually arranged so that the fire can be shaken by moving the bars4 ,for burning anthracite coal1 the grates are sometimes made of wrought-iron tubes1 through which a current of water circulates to prevent them from being overheated4 ,,question #ie4 ,how are cinders and burning coals prevented from falling through the grate upon the road8 ,answer4 ,by attaching a sheet-iron receptacle or ash-pan 7d d1 fig4 #da7 as it is called1 under the grate1 which it completely encloses from the outside air4 ,this then serves two purposes1 as it is often important when the engine is standing still to prevent any access of air to the fire-box1 and therefore the ash-pan is made to fit tightly to the fire-box4 ,suitable doors1 or dampers as they are called1 are placed in front and behind1 and sometimes on the sides1 which can be opened or closed to admit or exclude air as may be needed4 ,,question #if4 ,how are the tubes or flues of a locomotive arranged8 ,answer4 ,they are fastened into accurately drilled holes in the tube sheet 7a1 a1 figs4 #da and #db7 which forms the front of the fire-box and in similar holes in a plate 7a1 a1 fig4 #da17 which forms the front end of the cylindrical part of the boiler4 ,they thus connect the fire-box with the smoke-box4 ,the tubes are arranged so that each tube will have a space of from to of an inch between it and those adjoining4 ,the position of the holes for the tubes in relation to each other is determined by describing from the centre of one tube 7o1 fig4 #dd7 a circle with a radius1 o k1 equal to the sum of the diameter of a tube and the distance which they are intended to be apart1 and then subdividing this circle with the radius into six parts1 k1 r1 s1 l1 g and p4 ,each point of subdivision and also the centre1 o1 of the circle will be the centre of a tube4 ,by drawing them from these centres it will be found that the distances a b1 c d between adjoining tubes will be the same between all of them4 ,by describing circles from the centres of the outside tubes and subdividing the circles as before the position of other tubes will be determined around those first laid down4 ,this can1 of course1 be carried out indefinitely4 ,a difference in the arrangement of the tubes will be observed if1 when we subdivide the first circle shown in fig4 #dd1 instead of commencing from the intersection of a vertical line we begin from a horizontal line1 h i1 as shown in fig4 #de4 ,in the former case the tubes are said to be in vertical rows1 and in the latter in horizontal rows4 ,it is apparent from the figures and as shown by the arrows that the water can circulate in ascending currents more freely when tubes are arranged in vertical rows than when they are arranged horizontally4 ,illustration3 ,fig4 #dd4 ,scale 4 ,illustration3 ,fig4 #de4 ,scale 4 ,,question #ig4 ,how are the tubes fastened and made water-tight in the tube-sheets8 ,illustration3 ,fig4 #df4 ,scale 4 ,illustration3 ,fig4 #dg4 ,answer4 ,they are inserted into the holes drilled to receive them1 and the ends are allowed to project about a quarter of an inch beyond the tube-sheets4 ,a tapered plug1 fig4 #df1 is then driven into the tube1 to expand it so that it will fit the hole4 ,a tool is used called a tube-expander1 fig4 #dg1 which is what might be called an expanding plug1 consisting of a number of sections1 a1 b1 c1 d1 e1 f1 g1 h1 held together by a spring clasp s1 which embraces them1 as shown in the engraving4 ,this plug when the sections are drawn together is inserted into the mouth of the tube1 and the tapered plug p p1 is then driven into the opening left in the center of the cluster of sections1 which are thus expanded4 ,by this means1 the ridge a b c d expands the tube at the inner edge of the tube-sheet1 forming a ridge or corrugation1 as shown at c c1 fig4 #dh4 ,at the same time the shoulder j k l on the tool expands the outer edge of the tube somewhat as is shown at f f1 fig4 #dh4 ,by repeating this process1 and slightly turning the expander each time1 the tubes can be made perfectly water-tight4 ,there are other forms of tube-expanders1 but the one described1 known as ,prosser's expander1 is more generally used than any other4 ,in many cases1 after the tubes are expanded with the tool described1 the outer edge is turned over still more with what is called a thumb-tool1 fig4 #di1 probably from its resemblance in form to a man's thumb4 ,by placing the curved shoulder a on the end f1 fig4 #dh1 of the tube it is turned over1 somewhat in the form shown in the engraving1 by repeated blows of a hammer on the end of the tool4 ,copper ferrules1 represented by the black shading1 a a1 are also much used now on the outside of locomotive tubes1 and it is said that with them the joints can be kept tight much easier than without4 ,by turning over the outside edge of the tube as shown in fig4 #dh1 it not only protects the copper ferrule1 but1 as the tubes must act as braces to sustain the pressure of steam in the flat tube-sheets1 it gives the joints the requisite strength for resisting such strains4 ,illustration3 ,fig4 #dh4 ,scale 4 ,illustration3 ,fig4 #di4 ,,question #ih4 ,how can the strain on the cylindrical part of a boiler be calculated8 ,answer4 ,,by ,,multiplying ,,the ,,diameter ,,in ,,inches ,,by ,,the ,,length ,,in ,,inches ,,and ,,the ,,product ,,by ,,the ,,steam-,,pressure ,,per ,,square ,,inch4 ,thus for a boiler #dh inches in diameter and #aj feet long with #ajj pounds pressure the calculation would be #dh #abj #ajj #egf1jjj lbs4 ,,question #ii4 ,why do we multiply the diameter1 instead of the circumference1 by the length1 to get the strain on the cylindrical part8 ,answer4 ,the reason for multiplying by the diameter instead of by the circumference is because only a portion of the pressure on the inside surface of the boiler exerts a force to burst the shell at any one point4 ,thus1 supposing the following diagram1 fig4 #ej1 to represent a section of a boiler1 if we have a force acting on the shell in the direction of the line a b1 at the point b1 where it is exerted against the shell of the boiler1 it would be composed of two forces1 one acting in the direction b e1 and tending to tear the boiler apart on the line c d1 and the other acting in the direction f b1 to tear it apart on the line h g4 ,it is so with all pressure inside the boiler1 excepting that1 say a h1 which acts exactly at right angles to the line of rupture c d1 it is all composed of two forces1 only one of which tends to tear the boiler apart at one point4 ,it is therefore only a part of the pressure on the circumference which tends to burst the boiler at a given place1 and that part is equivalent to the pressure on a surface whose width is equal to the diameter and not the circumference4 ,illustration3 ,fig4 #ej4 ,illustration3 ,fig4 #ea4 ,this we know is a little difficult for those to understand who are not familiar with the principles of what is called the 8resolution of forces10 and we will therefore try to make it clear in another way4 ,to do this we will suppose that we have a boiler1 a b1 fig4 #ea1 made in two halves and bolted together at a and b by flanges4 ,it is evident that if we brought a pressure against the inside of the flanges in the direction of the darts c and d1 such a pressure would not have a tendency to tear apart the bolts a and b4 ,some distortion of the boiler might in fact take place1 if1 for example1 we put a jack-screw inside and forced out the flanges as indicated1 without subjecting the bolts to a tensile strain4 ,we see therefore that the forces acting in the direction c and d have no tendency to tear apart the bolts at a and b1 but it is only the forces such as e1 f and g1 which act at right angles to a b1 that exert a strain on the flanges4 ,that this force is equivalent to a pressure on a surface with a width equal to the diameter of the boiler is apparent if we suppose that we have a boiler1 a b1 fig4 #eb1 and that each half1 c and d1 is nearly filled with some substance1 say wood or cement1 which is fitted so tight that no steam can get between it and the shell of the boiler4 ,it is apparent now that if we admit steam into the space f1 the force exerted on the bolts a and b is that due to the pressure on the surface of the wood or cement exposed to the steam whose width is equal to the diameter of the boiler4 ,it might be said though that if this substance were elastic1 like india-rubber1 the effect of the steam would be different4 ,if it were elastic1 and a pressure on the surfaces f caused it to spread in the direction g and h so as to produce a pressure in those directions1 it would1 as has already been shown1 not exert a force on the bolts a and b to tear them apart1 but have a tendency to rupture the boiler at right angles to a b4 ,the sides of the boiler must therefore have a strength sufficient to resist this force which tends to tear them asunder4 ,if the boiler is made of iron inch thick there would be a sectional area of #de square inches on each side1 or a total of #ij square inches1 to resist this strain1 so that each square inch must bear #f1djj lbs4 of strain4 ,the correctness of this rule can be demonstrated by the use of mathematics1 which would be out of place here4 ,its practical truth has however been proved by experiment4 ,illustration3 ,fig4 #eb4 ,,question #ajj4 ,how much strain per square inch is good boiler plate capable of resisting1 and how much is it safe to subject it to8 ,answer4 ,there is great variation in the tensile strength#bg of rolled iron boiler plate1 but that of good plate will average about #ej1jjj pounds per square inch1 if the strain is applied in the direction of the 8grain0 or the fibres of the iron#bh1 and about ten per cent4 less if the strain is applied crosswise of the grain4 ,it has1 however1 been found by experiment that when a tensile strain is applied to a bar of iron or other material1 it is stretched a certain amount in proportion to the length of the bar and to the degree of strain to which it is subjected4 ,it is found that if this strain does not exceed about one-fifth of that which would break the bar1 it will recover its original length1 or will contract after being stretched1 when the strain is removed4 ,the greatest strain which any material will bear without being permanently stretched is called its limit of elasticity1 and so long as this is not exceeded no appreciable permanent elongation or 8set0 will be given to iron by any number of applications of such strains or loads4 ,if1 however1 the limit of elasticity is exceeded1 the metal will be permanently elongated1 and this elongation will be increased by repeated applications of the strain until finally the bar will break4 ,at the same time the character of the metal will be altered by the repeated application of strains greater than its elastic limit1 and it will become brittle and less able to resist a sudden strain1 and will ultimately break short off4 ,it is therefore unsafe to subject iron1 or in fact any other material1 to strains greater than its elastic limit4 ,this limit for iron boiler plates may be taken at about one-fifth its breaking1 or1 as it is called1 ultimate strength4 ,it should be remembered1 however1 in this connection1 that it often happens that the steam pressure is not the greatest force the boiler must withstand1 as sudden or unequal expansion and contraction are probably more destructive1 to locomotive boilers especially1 than the pressure of the steam4 #bg ,a force exerted to pull any material apart is called a tensile strain1 and if exerted to compress it is called a compressive strain4 #bh ,it should be explained that in the process of manufacturing iron by rolling1 the iron is stretched out into fibres in the direction in which it passes between the rolls4 ,,question #aja4 ,how are the plates of boilers fastened together8 ,answer4 ,with rivets1 which are made with a head at one end1 and are inserted while they are red-hot into holes drilled or punched in the edges of the plates4 ,after they are in the holes a head is formed on the other end1 either with blows from hand hammers1 or by a machine constructed for the purpose4 ,in these machines the rivet after it is in the holes is brought between a fixed and a movable die1 the head which is made with the rivet being placed against the fixed die1 and the movable die is then pressed1 either by steam or hydraulic pressure with great force against the other end of the rivet1 thus forcing the end of the rivet into the form of the die1 which is made of the proper shape and size for the rivet head4 ,the powerful pressure which is thus brought on the rivet causes it to be pressed into all parts of the two holes1 thus completely filling them both2 whereas with hand riveting1 the holes are not nearly so completely filled1 as it is impossible with blows of a hammer to subject the rivets to so powerful or uniform a pressure as the machine brings upon them4 ,illustration3 ,fig4 #ec4 ,,question #ajb4 ,what is the strength of riveted seams compared with that of the solid plate8 ,answer4 ,the strength of a riveted seam depends very much upon the arrangement and proportion of the rivets1 but with the best design and construction1 the seams are always weaker than the solid plates1 as it is always necessary to cut away a part of the plate for the rivet holes1 which weakens the plate in three ways3 #a4 ,by lessening the amount of material to resist the strains4 #b4 ,by weakening that left between the holes4 #c4 ,by disturbing the uniformity of the distribution of the strains4 ,the first cause of weakness is obvious from an inspection of an ordinary seam1 riveted with a single row of rivets1 fig4 #ec4 ,in this we have two plates #g inches wide and thick fastened with four rivets inches in diameter and #a inches from centre to centre4 ,the section of the plate calculated with decimals#bi would therefore be 4#cge #g4e #b4ha square inches4 ,a piece inch wide and inch thick would be removed to form each hole1 or a sectional area for the whole plate of 4#cge 4#fhge #d #a4jc square inches1 so that the section of the plate would be reduced through the holes #b4ha - #a4jc #a4gh square inches4 ,in other words1 on the dotted line a b it will have only about #fc per cent4 of the sectional area of the solid plate4 #bi ,in the following calculations all the dimensions have for convenience been reduced to decimals4 ,the second cause of the reduction of strength is owing to the injury sustained by the plates during the process of drilling and punching4 ,the knowledge existing regarding this subject is not very accurate1 although numerous experiments have been made to determine the exact amount of weakening caused by punching plates4 ,it is1 however1 certain that in many cases the strength of the metal left between the holes of boiler plates is reduced from #aj to #cj per cent4 by the process of punching4 ,it is probable1 however1 that soft ductile metal is injured less than that which is harder and more brittle4 ,some kinds of steel plates are especially liable to injury from punching4 ,it is also probable that the condition of the punch1 and the proportions of the die used with it1 have much to do with its effect upon the metal ,the third cause of weakness is owing to the fact that if one or more holes are made in a plate of any material1 and it is then subjected to a tensile strain1 the strain1 instead of being equally distributed through the section left between the holes1 will be greatest in that part of the metal nearest them4 ,this can be illustrated by taking a band of india-rubber1 fig4 #ed1 and cutting a round hole in it to represent a rivet hole4 ,if we draw two parallel lines1 ,a ,b1 across the band and then stretch it1 the lines1 instead of remaining parallel when the band is stretched1 will separate most next to the hole1 as shown in fig4 #ee1 indicating that the fibres of the rubber nearest the hole are strained most4 ,a similar effect takes place when a plate of iron is stretched1 so that a fracture is liable to begin next to the hole1 after which the plate will be broken as it were in detail4 ,illustration3 ,fig4 #ed4 ,illustration3 ,fig4 #ee4 ,,question #ajc4 ,how may a boiler seam like that shown in fig4 #ec break8 ,answer4 ,it may break in three different ways3 #a4 ,by the plate tearing between the rivet holes on the line a b4 #b4 ,by the rivets shearing off4 #c4 ,by the plate in front of the rivets crushing1 as shown in fig4 #ef4 ,illustration3 ,fig4 #ef4 ,,question #ajd4 ,how can the strength of a boiler seam be calculated at each of these three points8 ,answer4 ,the strength through the rivet holes is calculated by ,,taking ,,the ,,area ,,in ,,square ,,inches ,,of ,,the ,,metal ,,which ,,is ,,left ,,between ,,the ,,rivet ,,holes1 ,,and ,,multiplying ,,it ,,by ,,the ,,ultimate ,,strength ,,of ,,the ,,metal ,,after ,,the ,,holes ,,are ,,made4 ,thus1 in fig4 #ec1 the area of each of the plates between the rivet holes is #a4gh square inches4 ,as already stated1 good boiler plate will break at a strain of about #ej1jjj pounds in the direction of its fibres1#cj but the strength of the metal left between punched holes is probably #bj per cent4 and that between drilled holes #aj per cent4 less than that of the solid plate4 ,we must1 therefore1 in calculating the strength of a punched seam1 take the ultimate strength of the metal between the holes at only #dj1jjj pounds per square inch4 ,the calculation for the strength through the holes would therefore be3 #a4gh #dj1jjj #ga1bjj pounds4 #cj ,boiler plates should always be so arranged that the greatest strain will come on them in the direction of their greatest strength1 which is parallel with the fibres of the metal4 ,it has also been found by experiment that the strength of rivets to resist shearing is about the same as that of good boiler plate to resist tearing apart1 or #ej1jjj lbs4 per square inch4 ,the strength of the rivets1 therefore1 is calculated by ,,multiplying ,,the ,,area ,,in ,,square ,,inches ,,of ,,one ,,rivet ,,by ,,the ,,number ,,of ,,rivets1 ,,and ,,the ,,product ,,by ,,the ,,strength ,,of ,,the ,,metal ,,to ,,resist ,,shearing4 ,the calculation for fig4 #ec would therefore be3 ,area of rivet 4#cgab #d #ej1jjj #gd1bdj4 or a little more than the strength of the plates through the holes4 ,the resistance offered by a plate to the crushing strain of a rivet has been found also by experiment to be about #ij1jjj pounds per square inch4 ,it can be proved that the area which resists the crushing strain of a rivet in a plate1 fig4 #ec1 ,,is ,,measured ,,by ,,multiplying ,,the ,,diameter ,,of ,,the ,,rivet ,,by ,,the ,,thickness ,,of ,,the ,,plate4 ,the calculation for the strength of this part of the seam will therefore be3 diameter of hole 4#fhge 4#cge #d #ij1jjj #ib1hab4 ,the strength of the solid plate would be ,,equal ,,to ,,its ,,sectional ,,area ,,multiplied ,,by #ej1jjj ,,pounds1 or #g4e 4#cge #ej1jjj #adj1fbe pounds4 ,the ultimate strength of our seam would then be as follows3 ,plates through rivet holes 7tearing7 #ga1bjj lbs4 ,rivets 7shearing7 #gb1bdj lbs4 ,plates in front of rivets 7crushing7 #ib1hab lbs4 ,solid plate 7tearing7 #adj1fbe lbs4 ,it will thus be seen that the strength of the weakest part of the above seam1 fastened with a single row of rivets in punched holes1 is very little more than half 7#ej4f per cent47 of that of the plates4 ,it will be noticed that the weakest part of the seam is the plates between the holes4 ,illustration3 ,fig4 #eg4 ,illustration3 ,fig4 #eh4 ,illustration3 ,fig4 #ei4 ,illustration3 ,fig4 #fj4 ,,question #aje4 ,how can the strength of such a single-riveted boiler seam be increased8 ,answer4 ,the most obvious way of increasing the strength of such a seam is to place1 or1 as it is called1 space1 the rivets further apart1 which would leave more metal between the holes1 and thus strengthen the seam at its weakest part4 ,but if this is done1 it is said that there is difficulty in keeping the seam water-tight1 as the plates are then liable to spring apart between the rivets4 ,another way of increasing its strength is to drill the rivet holes4 ,as already stated1 the difference in the strength of the metal left between drilled and punched holes has been shown to be from #aj to #bj per cent4 ,there is also another advantage in drilling the holes for rivets4 ,in punching them1 it is necessary to punch each plate separately1 and even with the utmost care and skill it is impossible to get the holes to match perfectly4 ,some of them will overlap each other1 as shown in fig4 #eg1 so that when the rivet is set1 it will assume somewhat the form shown in fig4 #eh4 ,there is then danger that those rivets which fill the holes that match each other will be subjected to an undue strain4 ,if1 for example1 we have five rivet holes1 as shown in fig4 #ei1 and only the centre ones correspond with each other1 then the rivets in all the other holes will assume somewhat the form shown in fig4 #eh1 and therefore the centre rivet c1 in fig4 #ei1 which fits the holes accurately1 must take the strain of the other four until they draw up 8to a bearing40 ,under such circumstances1 which are not unusual1 there will be great danger either of shearing off the rivet c1 or of starting a fracture in the plates1 as indicated by the irregular line a b1 between the adjoining rivets4 ,it is also obvious that a rivet like the one in fig4 #eh will not hold the plates together so well as one which fits more perfectly1 as shown in section in fig4 #ec1 and therefore there is more danger of leakage between the plates from badly fitted rivets than from those which fill the holes more perfectly2 consequently rivets which fit imperfectly must be placed nearer together than those which are well fitted4 ,it is true that rivets which are set with a riveting machine fill any inaccuracies of the holes more perfectly than those which are set by hand4 ,but even if they are made to fill the holes as shown in fig4 #fj they are still not so strong to resist shearing nor so efficient in holding the plates together as they would be if the holes conformed more perfectly to each other4 ,in drilling the holes1 the second plate can be drilled from the holes in the first1 so that the holes in each will correspond with each other perfectly4 ,the rivets will therefore fit more accurately1 and consequently can be spaced further apart1 and still keep the plates tight1 and thus have more material between the holes1 which is the weakest part of the seam4 ,it has been shown that a rivet inch in diameter has a resistance to shearing of #ah1efj pounds4 ,there is therefore no advantage in spacing such rivets further apart than #a from centre to centre1 because the metal left between drilled holes that distance apart would be slightly stronger than the rivets4 ,if therefore the rivets are placed further apart1 their diameter must be increased4 ,there is1 however1 a limit beyond which the diameters of rivets cannot be increased with advantage1 because if we increase their diameters1 their sectional area to resist shearing is increased in proportion to the square of the diameter1 whereas the section of metal in the plate to resist crushing is increased only in proportion to the diameter4 ,this will be apparent if we compare a rivet inch with one #a inch in diameter4 ,the first has a sectional area of 4#aifc inch1 the other 4#ghed inch1 or four times that of the first one4 ,now the area which resists the crushing strain of the rivets is increased only in proportion to their diameters1 or is twice as much for the one as for the other4 ,if1 therefore1 we increase the diameters of the rivets1 we very soon reach a point at which the plate has less strength to resist crushing than the rivet has to resist shearing4 ,the diameter of rivet which will give just the same resistance to both strains varies with the thickness of the plates2 with inch plates a rivet will have a resistance to shearing of #cj1jfe pounds and the plate in front of it a resistance to crushing of #bi1ecj pounds4 ,a rivet is1 therefore1 the largest size which can be used to advantage in plates4 ,if now we were to space such rivets so far apart that the metal left between the holes would have a strength just equal to that of the rivets1 we would have the strongest possible seam that can be made with a single row of rivets4 ,this distance would be #a inches between the edges of the rivets1 or #b from center to center1 as shown in fig4 #fa4 ,the following table will show the strength of such a seam composed of four rivets1 and two plates #aj inches wide1#ca with drilled holes3 ,plates through rivet holes 7tearing7 #aah1abe lbs4 ,rivets 7shearing7 #abj1bfj lbs4 ,plates in front of rivets 7crushing7 #aah1abe lbs4 ,solid plates 7tearing7 #aif1hge lbs4 #ca ,it has been necessary to take for an illustration1 plates of a different width from the preceding example1 in order to get an even number of spaces between the rivets in each case4 ,illustration3 ,fig4 #fa4 ,from this it is seen that the strength of the seam with drilled plates is #fj per cent4 of that of the solid plates1 or it is about #ah per cent4 stronger than that made with plates having punched holes and the rivets nearer together4 ,it should be noted that a great part of the superiority of the seams made with drilled holes is due to the superior accuracy of the work done in that way1 which makes it possible to use larger rivets spaced further apart4 ,it is probable that with the use of some recently designed machines1 intended to produce greater accuracy in punching rivet holes1 part of the above advantage may be realized with that kind of work4 ,the greatest distance that rivets may be spaced apart without incurring danger of leakage between the plates must1 however1 be determined more by practical than theoretical considerations4 ,it is certain1 however1 that rivets may be spaced much further apart than they are in ordinary practice1 and the seams still be kept tight1 if the work is done with sufficient accuracy and care4 ,,question #ajf4 ,what other methods are there of making boiler seams which are stronger than those which have been described8 ,answer4 ,in this country two rows of rivets are used and also what is called a 8welt10 or covering-strip1 the latter with both single and double-riveted seams4 ,illustration3 ,fig4 #fb4 ,,question #ajg4 ,how are the rivets arranged when two rows are used8 ,answer4 ,they are often placed just behind each other as shown in fig4 #fb1 which is called chain-riveting4 ,such an arrangement of rivets obviously adds nothing to the strength of the seam1 because its weakest part1 as has already been shown1 is the section of the plates through the rivet-holes1 and this is not at all strengthened by adding another row of rivets1 because the plates are just as liable to break through the rivet-holes with two rows of rivets as they would be with one4 ,illustration3 ,fig4 #fc4 ,a much better arrangement is to place them alternately in the two rows1 as shown in fig4 #fc4 ,rivets arranged in that way are said to be staggered1 or placed zigzag4 ,the method of laying off the holes and proportioning such a seam in order to get the most strength is1 first1 to determine the greatest distance which can be allowed between the rivet-holes1 and yet keep the seams water-tight4 ,supposing this is #a inches1#cb with plates inch thick1 the diameter of rivet whose sectional area will give an equal amount of strength must then be calculated4 ,from the preceding data it will be found that for drilled plates the resistance of the portion left between such holes will be #bb1adh pounds1 and a rivet inch in diameter will have a resistance of #bb1jhe pounds4 ,on the line a b1 fig4 #fc1 which is to be the first row of rivets1 we will draw one hole1 c4 ,from the center of this hole we will describe the arc of a circle1 d e1 with a radius1 c d1 equal to the sum of the distance between the holes1 #a inches1 and one-half the diameter of the hole1 or inch1 making the radius #a inches4 ,from d1 the intersection of this arc with the line of rivets1 a b1 with the same radius1 we will step off the distance d f will then be the centre of the second rivet-hole on the line a1 b4 ,the rivet can therefore be drawn1 and from its centre1 with the same radius employed before1 another arc1 d g1 should be drawn4 ,if now we draw a rivet-hole 7h7 between the two arcs and touching each of them1 we will have all three of the holes so arranged that the metal between the holes c1 f1 will be just equal to that between them and the hole h4 ,in other words1 the strength of the plates on the line c f is just the same as on the line c h f4 ,therefore the strength of the plates on the straight line a b is just the same as on the zigzag line c h f1 etc4 ,the strength of this seam would therefore be as follows3 ,plates through rivet-holes 7tearing7 #aaj1gdb lbs4 ,rivets 7shearing7 #aaj1dbe lbs4 ,plates in front of rivets 7crushing7 #abf1efb lbs4 ,solid plates 7tearing7 #aeh1bje lbs4 #cb ,that and even greater distances between the edges of the holes are now used successfully with -inch plates4 ,the weakest portion of this seam1 it will be seen1 has a strength of #gj per cent4 of the plate1 or is #ch per cent4 stronger than a single-riveted seam with punched holes4 ,if we were to use inch rivets and make the spaces between them #a inches1 the strength of a similar seam would be as follows3 ,plates through rivet-holes 7tearing7 #adg1fef lbs4 ,rivets 7shearing7 #aej1cbe lbs4 ,plates in front of rivets 7crushing7 #adg1fef lbs4 ,solid plates 7tearing7 #bje1jgh lbs4 ,this seam would then have a strength of #gb per cent4 of the solid plates1 or be #db per cent4 stronger than the ordinary riveted seam with punched holes4 ,it is important to observe that an increase of strength results from the use of larger rivets spaced farther apart than is usual in ordinary practice1 and that this is possible only with the best and most accurate workmanship4 ,illustration3 ,fig4 #fd4 ,,question #ajh4 ,what is the form of construction of boiler seams made with a welt or covering-strip8 ,answer4 ,the plates 7a1 b1 fig4 #fd7 are lapped over each other as for an ordinary seam4 ,another plate1 c1 about nine inches wide1 is then placed on the inside of the seam and bent so as to conform to the lap of the two plates4 ,the rivets r1 whether a double or single row1 pass through all three plates1 and two more rows of rivets are put next to the edges of the covering plate1 c4 ,it is plain that the strength of the seam1 r1 is increased up to a certain point by an amount just equal to that of the rivets in the edges of the covering plate4 ,if1 however1 these are placed too close together1 the plates a and b will be weaker through the outside rows of rivets than the seam is through either of the outside ones and the middle one taken together4 ,if1 for example1 we take a single-riveted seam1 like that shown in fig4 #ec1 whose strength is only a little more than half that of the solid plate1 and should add to it a covering plate1 as shown in fig4 #fd1 and then space the rivets in the edges of the covering plate the same distance apart as in the middle seam1 then obviously the plates would be just as liable to break through the outer rows of holes as through the center row before the covering plate was added4 ,if1 however1 the holes in the two outside plates are spaced at say twice the distance apart1 or #c inches1 then the only way the seam can break through the outer rows of holes is by shearing the rivets1 because the plates between the holes are then stronger than the rivets4 ,but before these rivets can be sheared1 the centre seam must give way4 ,thus the strength of such a seam is equal to ,,the ,,sum ,,of ,,the ,,strength ,,at ,,the ,,weakest ,,points ,,of ,,the ,,middle ,,and ,,the ,,outside ,,seams4 ,the strength of the plates between the holes of the outside rows of rivets must1 however1 be as great as the sum referred to1 otherwise the seam will be the weakest at that point1 and the failure will occur there4 ,the rivets in the outside rows should be spaced at least twice as far apart as those in the middle seam4 ,the number of rivets to resist shearing will then be #ej per cent4 greater1 so that the strength of a seam like that shown in fig4 #ec1 with a covering plate added1 will be as follows3 ,plates through outside rows of rivet-holes 7tearing7 #ia1hhj lbs4 ,rivets in one outside and middle row 7shearing7 #aaa1cfj lbs4 ,plates in front of rivets 7crushing7 #aci1bah lbs4 ,solid plates 7tearing7 #adj1fbe lbs4 ,an ordinary single-riveted seam with punched holes1 with a welt or covering plate added1 would thus have a strength equal to #fe4c per cent4 of the solid plate1 or be #bi per cent4 stronger than the seam without the covering plate4 ,it is probable1 however1 that the injury to the plate from punching the outside rows of holes which are further apart is not so great as it is when they are punched nearer together and to the edge1 so that the strength is somewhat greater than our estimate4 ,the relative strength of the different forms of seams described in percentage of the strength of the solid plate is then as follows3 ,percentage of strength compared with solid plate4 ,single-riveted seam1 punched holes rivets #ej4f ,single-riveted seam1 drilled holes rivets #fj4 ,double-riveted seam1 drilled zigzag holes rivets #gj4 ,double-riveted seam1 drilled zigzag holes rivets #gb4 ,single riveted seam1 punched holes with covering plate #fe4c ,,question #aji4 ,are there any other forms of boiler seams used8 ,answer4 ,in ,europe what are called butt-joints are used to some extent4 ,in these the ends of the two plates abut against each other1 with a covering strip on one or both sides4 ,this form of joint is1 however1 not used in this country1 and therefore its peculiarities will not be described4 ,,question #aaj4 ,how are the seams of boilers made water-tight8 ,answer4 ,by what is called caulking4 ,that is1 by the use of a blunt instrument somewhat resembling a chisel1 the end of which is placed against one or both of the edges of the plates c1 d1 fig4 #ec1 which are then riveted down by blows of a hammer1 somewhat as the joints of a ship are made tight4 ,before the edges1 which are called the caulking edges1 of the plates are made tight in this way1 they are cut or trimmed off with a chisel4 ,in this process the plate under the edge is often injured seriously by the carelessness of workmen1 who sometimes allow the chisel to cut a groove in the plate under the edge1 thus weakening it at a point where the greatest strength is needed4 ,there is also danger of forcing the plates apart in the manner shown in fig4 #fe1 if it is done carelessly and with a heavy hammer4 ,illustration3 ,fig4 #fe4 ,,question #aaa4 ,how are the flat ends of the boiler strengthened8 ,answer4 ,by braces1 u1 u1 r1 r1 fig4 #da1 which are fastened to the end plates and to the outer shell of the boiler4 ,they are fastened at one end to shaped pieces called crow-feet1 which are riveted to the end plates of the boiler4 ,at the other end they are made with a broad foot1 which is riveted to the outer shell of the boiler4 ,especial attention should be given to the form1 proportion and arrangement of these braces when a boiler is constructed1 and they should be frequently examined while the engine is in use1 as they are liable to be neglected or carelessly constructed and to become weakened or broken by corrosion1 or the constant strain to which they are subjected4 ,great ignorance is often displayed in the design and proportions of these braces1 especially in their attachments to the shell of the boiler4 ,,question #aab4 ,how should the braces for strengthening the ends of a boiler be proportioned8 ,answer4 ,every part should be made equally strong4 ,if1 for example1 the brace itself is made of a bar of round iron one inch in diameter1 its sectional area would be 4#ghed square inch4 ,the iron used for these braces should be of such strength that a force of not less than #ej1jjj lbs4 per square inch of transverse section should be required to tear it apart lengthwise4 ,a bar of the size referred to would therefore require not less than #ci1bgj pounds to pull it apart4 ,all the other parts should be capable of resisting an equal strain4 ,it is1 for example1 not unusual to find a brace of the size we have described1 and even of larger diameter1 fastened to a crow-foot which is attached to the boiler plate with two rivets inches in diameter4 ,a similar fastening for the other end of the brace is also often used4 ,the sectional area of these two rivets is considerably less than that of the brace1 and at the same time the strain is brought upon them at such an angle as to have a tendency to 8snap0 them off4 ,for this reason1 and also because a rivet is apt to be deteriorated in strength by the hammering1 the rivets should always have a sectional area very nearly or quite double that of the bar which forms the brace4 ,the metal around the eyes through which the pins are inserted should also be carefully proportioned1 and the transverse section at any one point should always be at least #a times greater than that of the bar4 ,the area of the pins used for attaching the bars to the crow-feet should always be a little more than half that of the bar4 ,that is1 an inch bar should have a pin not less than inch in diameter4 ,when flat braces are used1 it is not unusual to find a bar #c inches wide with a hole an inch in diameter punched or drilled so near the end that a pin is sure either to pull out the end of the bar or else to break it crosswise at the hole with a much less strain than the brace itself would resist4 ,the ends of braces should always be enlarged enough to give them sufficient strength to resist as much strain as the bar itself4 ,although these precautions may appear unimportant1 and unfortunately are often so regarded1 yet it is upon just such details as these that the lives and the safety of every locomotive runner1 fireman and others near them are constantly dependent4 ,,question #aac4 ,how much water is usually carried in a locomotive boiler8 ,answer4 ,there must always be enough water in the boiler to cover completely all the parts which are exposed to the fire1 otherwise they will be heated to so high a temperature as to be very much weakened or permanently injured4 ,in order to be sure that all the heating-surface will at all times be covered with water1 it is usually carried so that its surface will be from #d to #h inches above the crown-sheet4 ,,question #aad4 ,how much space should there be over the water for steam8 ,answer4 ,no exact rule can be given to determine this4 ,it may1 however1 generally be assumed that the more steam space the better4 ,in order to increase the steam room1 locomotive boilers are very generally made in this country with what is called a wagon-top1 ,c1 fig4 #da1 that is1 the outside shell of the boiler over the fire-box is elevated from #d to #ab or even #ah inches above the cylindrical part4 ,,question #aae4 ,what is a steam-dome and for what purpose is it intended8 ,answer4 ,a steam-dome1 ,x1 fig4 #da1 is a cylindrical chamber made of boiler-plate and attached to the top of the boiler4 ,its object is to increase the steam room and to furnish a reservoir which is elevated considerably above the surface of the water1 from which the supply of steam to be used in the cylinders can be drawn4 ,the reason for drawing the steam from a point considerably above the water is that during ebullition more or less spray or particles of water are thrown up and mixed with the steam4 ,when this is the case1 steam is said to be wet1 and when there is little or no unevaporated water mixed with it it is said to be dry4 ,it is found by experience that wet steam is much less efficient than that which is dry4 ,there is also danger that the cylinders1 pistons or other parts of the machinery may be injured if much water is carried over from the boiler with the steam1 because water will be discharged so slowly from the cylinders that there is not time for it to escape before the piston must complete its stroke1 so that the cylinder-heads will be 8knocked out10 or the cylinder itself or the piston will be broken4 ,the reason for drawing or 8taking0 steam from a point considerably above the water is because there is less spray there than there is near the surface1 and the hottest steam1 which is also the dryest1 ascends to the highest part of the steam space4 ,,question #aaf4 ,where is the dome usually placed8 ,answer4 ,in this country it is usually placed over the fire-box1 but in ,europe it is placed further forward1 either about the centre of the boiler or near the front end of the tubes4 ,sometimes two domes are used on engines1 in this country1 one over the fire-box and another near the front end4 ,,question #aag4 ,how is the steam conducted from the dome to the cylinders8 ,answer4 ,by a pipe ,i m m1 fig4 #da1 called the dry-pipe1 which extends from the top of the dome to the front tube-plate4 ,on the front side of the tube-plate and inside the smoke-box two curved pipes1 ,o1 fig4 #da1 7shown also in fig4 #dj17 called steam-pipes1 are attached to the dry-pipe at one end1 and to the cylinders at the other4 ,the vertical portion of the dry-pipe in the dome1 sometimes called the throttle-pipe1 is usually made of cast iron1 the horizontal part of wrought iron1 and the steam pipes of cast iron4 ,,question #aah4 ,how is the loss of heat from locomotive boilers by radiation and convection prevented8 ,answer4 ,by covering the boiler and dome with wood1 called lagging1 about inch thick1 which is a poor conductor of heat1 and then covering the outside of the wood with ,russia iron1 the smooth1 polished surface of which is a poor radiator of heat4 ,,question #aai4 ,what is the smoke-box for8 ,answer4 ,the smoke-box ,q is simply a convenient receptacle for the smoke before it escapes into the chimney or smoke-stack1 which is attached to the top of the smoke-box4 ,it also affords a convenient place for the steam and exhaust pipes1 where they are surrounded with hot air and smoke1 and not exposed to loss of heat by radiation4 ,the front end of the smoke-box is usually made of cast iron1 with a large door in the centre which affords access to the inside4 ,,question #abj4 ,how are the chimneys or smoke-stacks of locomotives constructed8 ,answer4 ,the forms of smoke-stacks which have been used are almost numberless4 ,for burning bituminous coal and wood they are generally made with a central pipe1 ,r1 fig4 #da1 and a conical-shaped cast-iron plate1 ,s1 called the cone or spark deflector1 which1 as the latter name implies1 is intended to deflect the motion of the sparks and cinders which are carried up with the ascending current of smoke and air in the pipe ,r1 so as to prevent them from escaping into the open air while they are incandescent1 or 8alive40 ,a wire netting1 t t1 is also provided1 which is intended as a sort of sieve to enclose the sparks and cinders1 and at the same time allow the smoke to escape4 ,the receptacle h h is intended as a chamber in which the burning cinders will be extinguished before they escape4 ,for burning anthracite coal1 a simple straight pipe1 without a deflector or wire netting1 is ordinarily used4 ,,question #aba4 ,what are the proportions and materials usually employed in the construction of smoke-stacks8 ,answer4 ,the inside pipe ,r1 fig4 #da1 is usually made of the same diameter as the cylinders1 or an inch or two smaller4 ,for the other dimensions there are no established rules1 excepting for the height of the top of the chimney above the rail1 which is usually from #ad to #ae feet4 ,the outsides of smoke-stacks are made of sheet iron1 but the upper part is now sometimes made of cast iron1 so as to withstand the abrasion of the sparks and cinders longer than sheet iron will4 ,for very warm and damp climates1 the outsides of smoke-stacks are sometimes made of copper to resist corrosion1 which is very destructive to all iron structures in those countries4 ,the wire netting is made of iron or steel wire from to of an inch in diameter1 and with from #c to #d meshes to the inch4 ,,question #abb4 ,what is the pipe ,n1 fig4 #da1 intended for8 ,answer4 ,it is intended to conduct the exhaust steam and a portion of the smoke from the bottom of the smoke-box1 where the steam escapes1 to the base of the smoke-stack4 ,in nearly all ,european engines1 the exhaust steam escapes at the top of the smoke-box just below the aperture of the smoke-stack4 ,there is1 however1 often difficulty in equalizing the draft in the tubes1 that is1 to get an equal amount of smoke to pass through all of them4 ,by the use of the pipe ,p1 called the inside pipe or petticoat pipe1 it is thought that the draft in the tubes can be equalized much better1 as a part of the smoke is drawn out of the smoke-box at the top and part at the bottom of the smoke-box4 ,the pipe is usually made in two parts1 which slide into each other like a telescope4 ,the distance of the upper end from the top of the smoke-box and that of the lower end from the bottom can thus be increased or diminished1 and if the draft is greater through the upper tubes than through the lower ones1 or vice versa1 it can be regulated or equalized by simply raising or lowering the top or bottom of the petticoat pipe4 ,sometimes this pipe is made with openings and a kind of deflectors over them between the two ends4 ,it is then called a flounced petticoat pipe1 for obvious reasons4 ,no exact theory can be stated regarding the proportions of these pipes1 or the results effected by them1 which can be determined only by practical experience4 ,some more accurate knowledge concerning them is1 however1 much needed4 ,,part ,,viii4 ,,the ,,boiler ,,attachments4 ,,question #abc4 ,how is water supplied to the boiler to replace that which is converted into steam8 ,answer4 ,it is usually forced into the boiler against the steam pressure by force pumps1 but another instrument called an injector is now much used4 ,,question #abd4 ,what is the form of construction and principle of the operation of such force pumps8 ,answer4 ,the ordinary single-acting force pump1 fig4 #ff1 used on locomotive and other steam engines consists of a pump-barrel1 ,a ,a1 which is a cast-iron or brass cylinder in which a tight-fitting piston1 ,b ,b1 called the pump-plunger1 works4 ,this piston or plunger is simply a round rod which works air-tight through what is called a stuffing box1 ,c1 whose construction will be fully explained hereafter4 ,the plunger receives a reciprocating motion1 usually from the piston-rod of the engine1 but is sometimes worked by a small crank attached to one of the crank-pins1 or by an eccentric on one of the axles4 ,the pump-barrel is connected with the water-tank of the tender by the suction-pipe1 ,d1 and with the water-space of the boiler by the feed-pipe1 ,e ,e4 ,over the suction-pipe ,d is a valve1 ,f1 called the suction-valve1 which opens upward1 and below the feed-pipe1 ,e1 is another valve1 ,g1 called the pressure-valve4 ,these valves are cylindrical and made of brass1 and rest on brass seats1 g1 g1 to which they are fitted so as to be water-tight4 ,they work in guides1 k1 k1 called cages1 the form of which is more clearly shown in the section1 fig4 #fg1 and the plan1 fig4 #fh4 ,when the plunger is drawn out of the pump-cylinder it creates a vacuum behind it1 and the pressure above the valve ,g closes it1 while the atmospheric pressure on the water in the tank forces it into the suction-pipe1 opens the valve ,f1 and fills the pump-cylinder4 ,when the plunger is forced back again the force with which it presses against the water in the pump-barrel1 ,a1 closes the valve ,f1 and opens the pressure-valve ,g1 and the water is then forced through the feed-pipe into the boiler4 ,in order to be certain that the water in the boiler will not flow back into the pump1 and also to prevent all the water and steam in the boiler from escaping in case of accident to either the feed-pipe or pump1 another valve1 ,h1 fig4 #ff1 called a check-valve1 is placed between the feed-pipe and the boiler4 ,the construction of this valve is similar to that of the pressure and suction valves4 ,it is inclosed in a cast-iron or brass case1 ,i ,i4 ,all of these valves have cages in which they work and which also act as stops1 which prevent them from rising from their seats further than a certain distance4 ,this distance is called their lift1 and the successful working of the pumps depends very much on the amount of lift which the valves have4 ,this is usually from to inch4 ,illustration3 ,fig4 #ff4 ,illustration3 ,fig4 #fg4 ,illustration3 ,fig4 #fh4 ,over the pressure-valve ,g is a chamber1 ,j1 called an air chamber4 ,when water is forced into this chamber1 it is obvious that as soon as it rises above the mouth of the pipe ,e1 the air above the surface1 c d1 of the water will be confined in this chamber4 ,this confined air1 being elastic1 will be compressed and expanded by the pressure of the water1 so that it forms a sort of cushion1 which relieves the pump and the pipes from the sudden shocks to which they are subject1 owing to the rapid motion of the pump-plunger4 ,another air-chamber1 ,k ,k1 is sometimes placed below the suction-valve ,f4 ,the object of this is to supply a cushion to relieve the suction-pipe from the shock which is caused by the sudden arrest of the motion of the water in the pipe when the valve ,f is closed4 ,when the pump-plunger is drawn out1 the water flows through the valve ,f to fill the vacuum in the pump-barrel1 ,a ,a1 and consequently all the water in the suction-pipe is put in motion4 ,as soon as the plunger returns1 the valve ,f is closed and the motion of the water is suddenly arrested1 thus producing more or less of a shock in the pipe ,d4 ,when the water in the air chamber ,k ,k rises above the line a b1 it is evident that the air above that line will be confined in the space surrounding the pipe ,l4 ,this air then forms a cushion in the same way as that in the upper air chamber ,j does1 which has already been explained4 ,the advantages of the lower air chamber are1 it is thought1 more imaginary than real4 ,,question #abe4 ,how can the pump be taken apart and the valves examined8 ,answer4 ,by removing the bolts e1 e1 the upper air chamber can be taken off1 and by taking out the bolts f1 f1 the lower one can be taken down1 and the valves and cages removed4 ,the check-valve ,h can be taken out by removing the bolts l1 l1 which hold up the valve-seat h and the valve and cage4 ,,question #abf4 ,how can it be known whether the pump is forcing water into the boiler8 ,answer4 ,to show this a cock1 called a pet-cock1 is attached to the upper air chamber in the position shown by the dotted circle m4#cc ,by opening this cock1 if the pump is working1 a strong jet of water will be discharged from it during the backward stroke of the pump-plunger4 ,if the pump is not forcing water into the boiler1 or is working imperfectly1 the stream discharged from the pet-cock will be weak1 and the backward and forward strokes of the plunger will thus not be very definitely indicated by the discharge from the pet-cock4 #cc ,the pet-cock is sometimes attached to the feed-pipe4 ,another small cock is often attached to the lower air chamber1 or to the feed-pipe1 to allow the water to escape from the pump in cold weather1 when the engine is not working1 so as to prevent it from freezing4 ,,question #abg4 ,why is it necessary to be able to regulate the quantity of water which is forced into the boiler by the pumps8 ,answer4 ,because when the engine is working hard1 that is1 pulling a heavy load up a grade1 more steam and consequently more water are consumed than when it is not working so hard1 and therefore more water must be forced in to supply the place of that which is used in the form of steam4 ,if more water is forced in than is consumed1 the water will rise and fill the steam-space and a part of it will then be carried into the cylinders without being evaporated4 ,if too little water is forced into the boiler1 the heating surface will not be covered1 and there will consequently be danger that those portions which are exposed to the fire will be overheated and injured4 ,,question #abh4 ,how is the supply of water which is fed into the boiler by the pump regulated8 ,answer4 ,by a cock in the suction-pipe called a feed-cock1 which can be regulated by the locomotive runner1 so that more or less water is supplied to the pump4 ,there is also a valve in the water tank by which the supply of water can be regulated4 ,,question #abi4 ,on what part of the locomotive are the pumps usually placed8 ,answer4 ,they are usually attached to the frames behind the cylinders1 and are worked by the piston-rod1 as will be more fully explained hereafter2 but they are sometimes placed inside of the frames1 that is1 between the wheels1 and worked from an eccentric on one of the axles1 and sometimes they are placed outside of the wheels near the back part of the locomotive1 and worked from short cranks attached to the crank-pins4 ,,question #acj4 ,what provision is made for preventing the water in the pumps from freezing in cold weather8 ,answer4 ,pipes which communicate with the steam-space of the boiler are attached to each of the suction-pipes1 so that1 by opening valves in the former1 steam is admitted into the suction-pipes to heat the water in them4 ,by admitting this hot water into the pump1 it is kept warm1 and the water is thus prevented from freezing4 ,illustration3 ,fig4 #fi4 ,,question #aca4 ,what is an 8injector08 ,answer4 ,it is an instrument in which a jet of steam from the boiler mingles with and forces a continuous jet of water into the same boiler against its own pressure4 ,,question #acb4 ,what is the action of the injector and what are the names of its essential parts8 ,answer4 ,all injectors have certain parts in common4 ,these may be shown in the simplest form of instrument1 as in the fixed-nozzle injector1 a section of which 7omitting all detail of construction7 is shown in fig4 #fi4 ,the steam from the boiler1 passing through the pipe ,a1 enters the receiving-tube ,c4 ,here it is joined by the water which enters the pipe ,b4 ,the water condenses the steam in the combining-tube ,d1 and a water jet is formed which is driven across the overflow space ,f ,f1 and enters the delivery-tube ,h1 thence past the check-valve ,i into the boiler4 ,during the passage of the water from ,d to ,h1 as it passes across the overflow space ,f1 if too much water has been supplied to the steam1 some will escape at this point and flow out through the overflow nozzle ,g1 while if too little water has been supplied1 air will be drawn in at ,g1 and carried into the boiler with the water4 ,the names of the essential parts seem very applicable when we notice that steam is received from the boiler at ,c1 combines with the water at ,d1 and both are delivered to boiler through ,h4 ,,question #acc4 ,how is the operation of the injector explained8 ,answer4 ,steam escaping from under pressure has a much higher velocity than water would have under the same pressure and condition4 ,the escaping steam from the receiving-tube unites with the feed-water in the combining-tube1 and gives to this water a velocity greater than it would have if escaping directly from the water-space in the boiler4 ,the power of this water to enter the boiler comes from its weight moving at the velocity acquired from the steam1 and it is thus enabled to overcome the boiler pressure4 ,this can be illustrated with a wooden croquet ball1 which will float on the surface of water and will require considerable force to make it sink4 ,if1 however1 it is thrown violently into the water1 it will sink to a considerable depth before its buoyancy will overcome its momentum1 or actual energy4 ,if1 however1 we were to take a very light1 hollow wooden or india-rubber ball1 no matter how violently we throw it into the water1 it will not sink1 because the total actual energy of any body ,,is ,,proportional ,,to ,,its ,,weight ,,multiplied ,,by ,,the ,,square ,,of ,,its ,,velocity1 and therefore if we throw the hollow ball at the same velocity as the solid one1 the former will still have much less energy than the latter4 ,now1 as already stated1 steam under a given pressure escapes from an orifice with a very much greater velocity than water4 ,but steam being very light1 if its weight is multiplied by its velocity its total energy will be comparatively small4 ,now in the injector1 a portion of the high velocity of steam is imparted to the heavy water1 because this water is presented to the action of the steam1 not in a mass1 as in the boiler1 but in small quantity and in such a position that it can easily escape1 so that it gradually acquires as high a velocity as the escaping steam can impart1 and at the same time the steam is condensed1 and therefore there is a heavy substance with a high velocity1 whose actual energy is sufficient to overcome the pressure in the boiler4 ,if the steam were not condensed we would have a comparatively light substance moving at a high velocity1 which1 as has already been explained1 would have little actual energy1 and would therefore not overcome the boiler pressure4 ,,question #acd4 ,does this involve any principle like a perpetual motion1 or of work done without consumption of power8 ,answer4 ,no1 the steam escapes as steam1 and is returned to the boiler as water with its bulk reduced1 say #a1jjj times1 and if it carries with it twenty times its weight of fresh feed-water1 there would still be a loss of pressure or effective force in the boiler sufficient to do the work required in introducing the water4 ,,question #ace4 ,will the injector feed hot water8 ,answer4 ,the instrument will not work when the feed-water is too hot to condense the steam1 for the reasons given above1 and the amount of water thrown is always the greatest when the feed-water is the coldest4 ,steam at a low pressure can be condensed more readily than steam of higher pressure1 because it contains less heat4 ,the feed-water may be used hotter to condense low steam than to condense high steam4 ,in using the injector1 the lower the boiler pressure the hotter may be the water within certain limits1 the limit being the possible condensation of the steam4 ,,question #acf4 ,will a 8fixed-nozzle0 injector1 such as has been described1 answer as a boiler feeder on locomotives8 ,answer4 ,it will answer at some one pressure of steam1 to which pressure it may have been adapted in making the instrument1 and at that pressure it will work admirably2 but it will not work satisfactorily at any other pressure1 either higher or lower1 and has not much range in quantity of water delivered4 ,,question #acg4 ,what is required to make an injector work at different pressures8 ,answer4 ,the instrument must be so made that the water passage between the receiving tube and the combining tube can be varied in size4 ,this is usually done by making the combining and receiving tubes conical and moving the former to or from the latter1 thus contracting or enlarging the water space4 ,such adjustment must be made at each change of steam pressure in the boiler4 ,if this adjustment is made by hand1 as in some kinds of injectors1 it requires constant attention1 if the steam pressure varies frequently4 ,,question #ach4 ,how has this regulation been accomplished without such attention8 ,answer4 ,in the ,,self-,,regulating ,,injector1 fig4 #gj1 by using the escape water at overflow to push the combining tube towards the receiving tube and the indraught of water at the same place to pull the combining tube away from the receiving tube4 ,this can be explained as follows3 ,the case ,g of the instrument has two inlets1 one for steam1 the other for water1 the two being separated by the plate ,f ,f4 ,steam passes into the receiving tube ,a1 and its escape is regulated by a taper-plug in the end of the rod ,b1 moved by the handle ,h4 ,at the upper end of the combining tube ,c1 where it swells out into a bell mouth1 is a piston ,n ,n1 sliding in the case4 ,the lower end at ,c is guided by the upper end of the delivery tube ,d4 ,the delivery tube ,d is stationary4 ,the overflow opening is at ,o4 ,the action of this instrument may be thus described3 ,steam entering the receiving tube ,a escapes through its lower end when the plug ,b has been drawn back4 ,it unites with the water surrounding it in the space ,n ,n1 is condensed and passes with the feed-water into the delivery tube ,d1 and thence into the boiler4 ,if too much water enters the combining tube1 some will escape at the overflow ,o1 and filling the space below the piston ,n ,n1 will force the combining tube up toward the receiving tube1 and1 thus contracting the space between them1 will diminish the water supply2 while1 if it gets too little water in this space1 it will take some in at the overflow ,o1 and thus draw down the piston ,n ,n1 and enlarge the space1 giving more water to the instrument4 ,this self-regulating principle enables the instrument to continue working efficiently1 no matter how much the steam pressure in the boiler varies4 ,illustration3 ,fig4 #gj4 ,,question #aci4 ,how do you start this kind of injector8 ,answer4 ,the instrument just described is the latest form of self-regulating injector1 manufactured by ,messrs4 ,wm4 ,sellers ,co41 and is called by its makers the ,,injector ,,of #ahgf4 ,it is started and stopped by a simple movement of the lever ,h4 ,this lever ,h moves a cross-head ,i1 on the guide-rod ,j2 it also1 by means of stops ,t and ,q1 on rod ,l1 opens and closes the starting-valve ,k4 ,in fig4 #gj the instrument is shown shut off1 and with the starting-valve ,k open4 ,on the rod ,b are two valves1 a small one ,w and a larger one ,x4 ,a stop or collar is shown a short distance beyond the large valve ,x4 ,if the lever ,h be drawn back until this collar comes in contact with the valve ,k1 it will have raised the valve ,w from its seat1 and steam will escape through a small passage in the centre of the conical regulating plug4 ,the steam so admitted is sufficient to lift the water1 which will then be driven through ,d1 and past the valve ,k1 and escape at ,p4 ,drawing back the lever ,h to the end of its stroke1 after the water has been lifted1 the large valve ,x is raised1 and the lug on the lever ,h1 coming in contact with the stop ,t1 on the rod ,l1 the valve ,k is closed4 ,the jet is fully established and the water is driven into the boiler4 ,at the entire end of stroke of the lever ,h1 the latch ,v falls into notches on the rod ,j1 when1 as the lever is moved forward toward the position shown in fig4 #gj1 this latch will click over the notches and hold the lever in any desired position between the maximum and minimum delivery4 ,,question #adj4 ,what attachments are needed besides the instrument to render it effective8 ,answer4 ,a globe-valve should be placed in the steam pipe leading to the injector1 to be closed only when there is occasion to remove the injector when steam is up1 and in cold weather1 to prevent the condensation of steam in the pipes at the end of its trips4 ,during all the working time of the injector1 this valve should be wide open4 ,,question #ada4 ,in what position1 and in what location on the engine should the injector be placed8 ,answer4 ,on the right hand side1 high enough up to have an air chamber below the injector1 above the top of the water in the tank when the latter is full4 ,,question #adb4 ,what is required to keep the instrument in working order8 ,answer4 ,constant use is better than occasional use4 ,having two injectors on the same engine1 one on each side1 the one on the runner's side will be used while running4 ,the one on the other side should be used when standing4 ,all pipe connections must be tight1 so as to prevent the leaking of air4 ,the pipe carrying steam to the instrument should be from such part of the boiler as will insure the use of dry steam1 and the waste pipe must not be contracted4 ,the instrument represented in the engraving is the injector of #ahgf1 manufactured by ,messrs4 ,william ,sellers ,co4 of ,philadelphia4 ,beside this1 ,mack's and several other kinds of injectors are now used4 ,illustration3 ,fig4 #ga4 ,scale1 in4 #a foot4 ,,list ,,of ,,parts ,,designated ,,by ,,letters ,,of ,,reference ,,in ,,fig4 #ga4 ,a1 ,furnace ,door4 ,b1 ,b1 ,driving ,wheels4 ,c1 ,driving ,axle4 ,d1 ,d1 ,suction ,pipes4 ,e1 ,ash ,pan ,damper4 ,f1 ,f1 ,foot ,steps for getting on and off the ,locomotive4 ,g1 ,g1 ,hand ,holds for getting on and off the ,locomotive4 ,h1 ,i1 ,cab4 ,j1 ,j1 ,doors in front of ,cab4 ,k1 ,k1 ,windows in front of ,cab4 ,l1 ,steam ,gauge4 ,m1 ,spring ,balance4 ,n1 ,steam ,gauge ,lever4 ,o ,o1 ,throttle ,lever4 ,p1 ,water ,gauge4 ,q1 ,stand for ,tallow ,can4 ,r1 ,drip ,pipe for ,gauge ,cock4 ,t ,t1 ,rod for operating ,feed ,cock4 ,t1 ,regulator for ,feed ,cock4 ,u ,v1 ,reverse ,lever4 ,w1 ,whistle4 ,x1 ,blow-,off ,cock4 ,z1 ,z1 ,frames4 a1 a1 ,heater ,cocks4 a a1 ,heater ,pipe4 b1 ,blower ,cock4 c1 c1 ,oil ,cups for oiling ,main ,valves4 d1 ,handle for opening ,valves in ,sand ,box4 e1 e1 ,handles for opening ,pet ,cocks4 f1 ,handle for opening ,cylinder ,cocks4 g1 ,whistle ,lever4 h1 ,whistle ,handle4 h1 ,rod connecting ,whistle ,handle to ,whistle ,lever4 j1 ,handle for left hand ,feed ,cock4 m m1 ,lever for shaking ,grate ,bars4 n1 ,bell ,crank for opening front ,ash ,pan ,damper4 o1 o1 ,check ,chains4 p1 ,pipe for carrying off water from ,gauge ,cocks4 s1 s1 s1 s1 ,gauge ,cocks4 w1 ,handle for opening ,blow-,off ,cock4 ,,question #adc4 ,how can the height of the water in the boiler be known8 ,answer4 ,two appliances are used by which the height of the water in the boiler can be observed4 ,these are3 #a4 ,gauge or try cocks4 #b4 ,the glass water gauge4 ,illustration3 ,fig4 #gb4 ,scale 4 ,illustration3 ,fig4 #gc4 ,scale1 #c in4 #a foot4 ,every locomotive is provided with four or more gauge-cocks1 which are usually placed at the back end of the boiler1 where they can easily be seen and reached4 ,these cocks1 s1 s1 s1 s1 are shown in fig4 #ga1 which represents the back end of a locomotive1 and to which frequent reference will be made4 ,they are also shown on a larger scale in fig4 #gb1 which represents the end plate of the boiler in section4 ,they communicate with the inside of the boiler and are so placed that one is three or four inches above the other4 ,the two upper cocks are placed above the point where the surface of the water should be when the engine is working1 and the two lower ones below it1 so that the upper ones communicate with the steam space and the lower ones with the water4 ,when these cocks are opened1 if the water is at its proper height1 steam is discharged from the two upper ones1 and water from the two lower ones4 ,when a gauge-cock which communicates with the steam space is first opened1 it is usually filled with condensed water1 so that it should usually be kept open for a little while until this water is discharged4 ,if the upper cocks are opened and continue to discharge water1 they indicate that there is too much water in the boiler2 on the other hand1 if steam is discharged when the lower cocks are opened1 then there is too little water in the boiler1 and the heating surface is in danger of being exposed to the fire without being covered with water1 and consequently overheated1 or as it is called 8burned10 and so injured as to become too weak to bear the strain to which it is subjected by the pressure of the steam4 ,there is then great danger that the crown sheet may be crushed down by the pressure of the steam above it1 or that the boiler may be exploded4 ,even if no accident occur1 the boiler is in great danger of permanent injury from overheating when the water is allowed to get too low4 ,below the gauge-cocks s1 s1 s1 s1 fig4 #ga1 an inclined cylinder1 ,r1 called a drip-pipe1 is placed with openings to receive the water and steam which are discharged from the cocks4 ,this water is conducted away by the pipe p4 ,the water-gauge1 ,p1 fig4 #ga1 which is shown in section in fig4 #gc1 consists of an upright#cd glass tube1 a a1 which is from one-half to three-quarters of an inch in diameter1 and from #ab to #ae inches long4 ,the glass is about one-eighth of an inch thick4 ,at its ends it communicates with the steam and water of the boiler through brass elbows1 b1 c4 ,the openings in these elbows1 which communicate with the boiler1 are closed by the valves or plugs1 d1 e1 which are worked by screws and handles1 f1 g4 ,the glass tube1 when it is attached to the elbows1 is made steam-tight by rubber rings1 which are pressed tight around the tube by packing-nuts1 h1 i4 ,the elbows are provided with the valves1 d1 e1 so that in case the glass tube breaks the steam and water can be shut off1 so as not to escape through the elbows4 ,the lower elbow is provided with a blow-off cock1 k1 through which any sediment or dirt which collects in the glass tube or elbows can be blown out4 ,when the valves in the upper and lower elbows are opened the steam flows into the glass tube through the upper one1 and water through the lower one1 and the water assumes a position in the glass tube on a level with the surface of that in the inside of the boiler2 that is1 the position of the water in the boiler becomes visible in the glass tube4 ,on account of the constant variations of the water in the boiler1 the column of water in the glass never remains stationary1 but plays up and down as long as the boiler is working4 ,but if the communication between the glass tube and the boiler is closed1 then the water in the tube becomes stationary and the water gauge is useless4 ,in order that there may be no obstruction of the glass tube by mud or dirt from the water1 it must be blown out often4 ,to do this the lower valve1 e1 is closed1 and the blow-off cock1 k1 and the steam valve1 d1 are opened4 ,the steam pressure in the tube on top of the column of water will force it out of the blow-off cock1 and the mud and dirt will be carried with it4 #cd ,sometimes these tubes are1 for convenience1 inclined1 as shown in fig4 #ga4 ,if from any cause the glass tube is broken1 first of all the water-valve e should be closed and then the steam-valve d1 so as to prevent the hot water and steam which will escape from the broken glass from scalding those who are working the engine4 ,by unscrewing the nuts h and i the old glass can easily be removed and a new one substituted in its place4#ce ,care should be taken in putting in new glasses not to screw the packing nuts down any more than just sufficiently to make the rubber rings steam-tight around the glass tubes4 ,if they are screwed too tight they are apt to produce a strain on the tube1 so that the slightest expansion by heat or contraction from cold will break it4 #ce ,extra glasses should always be carried with an engine so as to be substituted in case of accident to the one in use4 ,illustration3 ,fig4 #gd4 ,scale #a in4 #a foot4 ,illustration3 ,fig4 #ge4 ,scale #a in4 #a foot4 ,,question #add4 ,how is the steam pressure in boilers prevented from exceeding a certain limit8 ,answer4 ,by what are called safety valves4 ,these consist of circular openings1 a1 fig4 #gd1 about three inches in diameter placed usually on the top of the dome1#cf and covered by a valve1 b1 which is pressed down either by a lever1 c c1 and spring1 d1 as shown in fig4 #gd1 or by a spring alone1 as in fig4 #gf4 ,two of these valves are usually placed on the top of the dome1 so that if one gets out of order the other one will allow the steam to escape as soon as its pressure exceeds that which1 it has been decided1 the boiler can safely bear4 ,this pressure1 in locomotive boilers1 is usually from #ajj to #acj pounds per square inch4 #cf ,one of these1 v1 is shown in fig4 #da4 ,,question #ade4 ,how is the amount of pressure which must bear on top of a safety-valve determined8 ,answer4 ,this pressure is determined ,,by ,,multiplying ,,the ,,area ,,of ,,the ,,opening ,,for ,,the ,,valve ,,in ,,square ,,inches ,,by ,,the ,,greatest ,,steam ,,pressure1 ,,in ,,pounds ,,per ,,square ,,inch1 ,,which ,,the ,,boiler ,,is ,,intended ,,to ,,bear4 ,thus1 if the opening for a safety-valve is three inches in diameter1 its area will be seven square inches1 and1 therefore1 if the greatest steam pressure which it is intended that the boiler shall bear is #ajj lbs4 per square inch1 the valve must be pressed down with a pressure equivalent to #g #ajj #gjj pounds4 ,if the pressure on the valve is produced by a lever1 as in fig4 #gd1cg then the total weight of the safety-valve must be ,,multiplied ,,by ,,the ,,short ,,arm ,,of ,,the ,,lever1 7or the distance ,a between the centre of the fulcrum e and that of the load f17 ,,and ,,divided ,,by ,b1 ,,the ,,total ,,length ,,of ,,the ,,lever4 ,in fig4 #gd the short arm of the lever is #c inches1 and the whole length #ce inches2 therefore if the valve is to be pressed down with a pressure of #gjj pounds1 the pressure on the end of the lever would be calculated as follows3 #gjj #c ---------- #gj lbs4 #ce #cg ,the lever is represented in the engraving with a piece broken out1 in order to save room4 ,the spring d must therefore pull down on the end of the lever with a tension equal to #gj pounds4 ,when the pressure of the spring bears directly on the valve1 as shown in fig4 #gf1 then the tension of the spring must be just equal to the pressure on the valve4 ,this tension is produced by screwing down the nuts1 c1 c4 ,the spring d1 which produces the requisite pressure on the end of the safety-valve lever1 fig4 #gd1 is arranged inside of two cylinders1 g and h1 which slide over or into each other like the sections of a telescope4 ,this arrangement is called a spring-balance4 ,the spring1 d1 is attached to the covered ends and draws them towards each other4 ,the upper cylinder g is connected by a rod1 i1 to the flattened end of the lever c1 which has a hole drilled through it to receive the rod4 ,the other end of the rod is screwed into the upper cylinder g4 ,this rod is sometimes arranged so that it can be either lengthened or shortened by the nut j4 ,by lengthening or shortening the distance1 the tension of the spring is either diminished or increased4 ,the lower cylinder of the spring-balance1 represented in fig4 #gd1 is attached to a lever1 m1 which is fastened to the back of the steam-gauge k4 ,this is shown more clearly by fig4 #ge1 which represents the back of the gauge1 and also the lever1 l m1 whose fulcrum is at m4 ,the spring-balance is attached to the lever at k4 ,by drawing down the lever the tension of the spring is increased1 and by raising it up it is diminished4 ,the lever is held in any desired position by the latch1 n1 and the ratchet r r4 ,by this contrivance1 which is employed on the engines built at the ,grant and also at the ,baldwin ,locomotive ,works1 the pressure on the valve can at once be either increased or diminished1 which it is often desirable to do1 especially when an engine is not at work4 ,the spring-balance is shown in fig4 #ga1 and is indicated by the letter ,m and the lever by ,n4 ,unless the pressure of the steam exceeds that on top of the valve1 it will of course not be opened4 ,as there is always danger that a safety-valve or some of its attachments may become corroded or otherwise disordered1 so that it will not act promptly or with certainty1 it is desirable to open it frequently1 so as to be sure that it is in good working order4 ,to do this the pressure on the valve must be reduced below that in the boiler1 which can very conveniently be done with the spring-balance lever which has been described4 ,the lower cylinder of the spring-balance sometimes carries an index or pointer1 t1 fig4 #gd1 which protrudes through a slot in the cylinder g1 and indicates the amount of pressure of the spring on a scale marked along the slot on the outside of the cylinder4 ,if it is desired that the safety-valve should open when the steam pressure reaches #ajj or any other number of pounds per square inch1 the spring-balance is subjected to a tension which will bring an amount of pressure on the top of the safety-valve equal in pounds per square inch of its surface to that of the steam pressure desired4#ch #ch ,in loading a safety-valve allowance must always be made for the weight of the lever and the valve4 ,there should always be some provision made which will render it impossible to increase the steam pressure beyond that which it has been determined that the boiler will safely bear4 ,this is usually done by arranging one of the safety-valves with a lever1 as shown in fig4 #gd1 and the other without1 like that in fig4 #gf4 ,the latter is often covered and sealed or locked up1 so as to be beyond the control of the locomotive runner4 ,the safety-valves are usually fitted into conical seats1 ,s ,s1 figs4 #gd and #gf1 so as to be perfectly steam-tight1 and are made with wings or guides1 t1 t1 the form of which is shown in the sectional plan ,a1 figs4 #gd and #gf1 under the valve4 ,these guides are intended to keep the valves in the proper positions in relation to their seats4 ,illustration3 ,fig4 #gf4 ,scale 4 ,as soon as the steam pressure under the valves becomes greater than the pressure of the springs on top of them1 the valves will be lifted up and the steam will escape until the pressure in the boiler is relieved4 ,it will be seen1 however1 that although the surface of the valve which is exposed to the pressure of the steam is equal to the area of the opening for the valve1 after it is lifted from its seat and the steam escapes all around the edge1 a larger surface will be exposed to the pressure of the escaping steam4 ,for this reason1 it will be found that after a valve is opened steam will escape1 or 8blow off10 as it is termed1 until the pressure is several pounds lower than it was when the valve first opened4 ,advantage has been taken of this fact in the valve shown in fig4 #gf1 which is called the 8,richardson0 valve1 which is now much used4 ,the top of this valve is made larger in diameter1 so as to expose more area to the escaping steam4 ,grooves are also made around the edge of the valve and the seat4 ,these1 it is claimed1 produce some sort of reflex action of the steam1 which keeps the valve open longer than it otherwise would be4 ,illustration3 ,fig4 #gh4 ,illustration3 ,fig4 #gg4 ,,question #adf4 ,how is the steam pressure in the boiler indicated8 ,answer4 ,by an instrument called a steam-gauge4 ,there are a great variety of such instruments made1 but they may all be divided into two classes1 and they all operate upon one of two principles4 ,in the one class the pressure of the steam acts upon a diaphragm or plate of some kind1 as shown in fig4 #gg1 which represents a section of a gauge of this kind2 a b is a metal plate made with circular corrugations1 as shown in section and also by the shading in fig4 #gh1 which represents a front view of the gauge with a part of the dial-plate removed4 ,the steam enters by the pipe c and the small opening d1 and fills the chamber e behind the metal plate or diaphragm4 ,the corrugations of the latter give it sufficient elasticity1 so that when the pressure is exerted behind it1 it will be pressed outward by the steam4 ,if it were flat1 it is plain that it would not yield1 or only to a very slight degree1 to the pressure of the steam4 ,in the centre of the diaphragm on the outside is a pin or stud1 f1 which bears against the plate4 ,this stud is attached to a bent lever or 8bell-crank10#ci g h k1 whose fulcrum is at h4 ,to the outer end1 k1 a rod1 l1 figs4 #gg and #gh1 is attached1 the lower end of which is connected to the short arm m of a toothed segment1 n1 whose fulcrum is at o4 ,this segment gears into a small pinion1 p1 which is attached to a spindle or shaft1 which carries a pointer1 fig4 #gh4 ,it is obvious now that if the diaphragm1 a b1 is pressed outward1 it will move the bent lever k h g1 the motion of which will be communicated by the rod l to the toothed segment n1 which will in turn revolve the pinion p1 and thus move the hand or index4 ,we have selected for this illustration one of many forms of this kind of gauge4 ,the mechanical appliances for communicating the motion of the diaphragm to the index or pointer are different in the gauges made by different manufacturers4 ,the form of the diaphragm also differs4 ,in some cases it is made of a metal plate2 in others a spiral spring is used1 covered with india-rubber to make it steam-tight4 ,the steam-gauge represented by figs4 #gg and #gh is the form manufactured by ,m4 ,b4 ,edson1 of ,new ,york4 #ci ,a bell-crank is a lever with an elbow in it4 ,illustration3 ,fig4 #gi4 ,illustration3 ,fig4 #hj4 ,in the other class of gauges1 shown in fig4 #gi1 the steam acts upon a bent metal tube1 a b c1 usually of a flattened or elliptical section4 ,it may not be known to all readers that if a tube bent1 say in the form of the letter ,u or ,c1 is subjected to the pressure of a liquid or gas on the inside1 the force exerted by the pressure has a tendency to straighten out the tube4 ,this is due to the tendency which a tube of an elliptical or flat section has to change the shape of the latter and approximate to a circular form when the inside is subjected to a pressure4 ,thus let ,a ,b1 fig4 #hj1 represent a cross section1 and a b d c1 a longitudinal section of a part of such a tube contained between two radii1 ,o a and ,o b1 drawn from the centre ,o of the curve in which the tube is bent4 ,if now we subject the inside of ,a ,b to a pressure it will have a tendency to assume the form of the circle ,c ,d1 and would then be represented in the longitudinal section by the dotted lines a b d c4 ,if now we draw radial lines through a c and b d1 it will be found that they intersect at ,o1 instead of ,o1 which was the original centre of the curve of the tube4 ,it will be seen that as the section of the tube approximates to the form of a circle1 the portion a b which is outside the curve will be moved farther from the centre1 while the other side1 c d1 is moved nearer to it4 ,as indicated by the radial lines1 when this occurs either the outside must be lengthened and the inside shortened1 to conform to the radial lines a ,o and b ,o1 or else the tube will be straightened so that the radial lines will assume the position a ,o and b ,o4 ,the phenomenon of the straightening of the bent tubes of steam gauges is frequently attributed to the difference between the area of the inside and outside of the curve4 ,this error was shared by the writer1 until the fallacy of the reasoning which supported it was pointed out to him4 ,in the gauge represented in fig4 #gi1 7in which the dial-plate is removed71 one end1 c1 of the tube is attached at d to a lever which has a toothed segment1 e1 at the other end4 ,the end a of the tube is connected with the lever at f4 ,the connection at d1 therefore1 forms the fulcrum of the lever4 ,it is obvious that as the two ends of the bent tube are forced apart by the steam pressure1 the lever and the segment have motion imparted to them4 ,the latter gears into a pinion on the spindle of the index or pointer1 r r1 which thus indicates on the dial the degree of pressure in the tube4 ,the latter is connected with the boiler by a tube attached at g4 ,various forms of this kind of steam-gauge are also made1 but all act on essentially the same principle4 ,the position of the steam-gauge on the engine is shown at ,m1 in fig4 #ga4 ,,question #adg4 ,why is the pipe which connects the steam-gauge with the boiler bent as shown in fig4 #ga8 ,answer4 ,to prevent the hot steam from coming in contact with the metal plate or tube1 as it is found that the heat of the steam affects their elasticity4 ,when a bent tube is used1 the steam from the boiler is condensed and fills the bent portion so that when the steam pressure comes on the surface of the water it forces it up the other leg of the tube into the gauge4 ,a cock is attached to this pipe so that the steam can be shut off in case the gauge should get out of order or require to be removed while there is steam in the boiler4 ,,question #adh4 ,how can the accuracy of a steam-gauge be tested8 ,answer4 ,when the gauge is in good working order1 the index or pointer moves easily with every change of pressure in the boiler1 and if the steam is shut off from the gauge1 the index should always go back to #j4 ,in order to determine the accuracy of its indications1 however1 they should be tested with a column of mercury4 ,this consists of a long1 vertical tube1 terminating at its base in a closed vessel filled with mercury4 ,the gauge is then attached to the top of this vessel and water or oil is forced into the vessel on top of the mercury and into the gauge4 ,a pressure of one pound per square inch will force up the column of the mercury #b4jd inches1 so that by graduating the tube into spaces that distance apart1 the divisions will indicate the pressure in pounds per square inch4 ,thus1 a pressure of #ej pounds would force up the column of mercury #ajb inches1 and with #ajj pounds pressure the column would rise #bjd inches1 and therefore1 when the mercury reaches these or any other points1 the steam-gauge1 if it is accurate1 should indicate equivalent pressures4 ,the ordinary steam-gauges are very liable to get out of order1 and therefore they should be frequently tested to ascertain whether their indications are correct4 ,,question #adi4 ,what is the steam whistle1 and for what purpose is it used8 ,answer4 ,the steam-whistle1 ,w1 fig4 #ga1 and shown in section on a larger scale in fig4 #ha1 consists of an inverted metal cup or bell1 ,a1 made usually of brass4 ,the lower edge of this cup is placed immediately over an annular opening1 a a1 from which the steam escapes and strikes the edge of the cup or bell1 which produces a deep or shrill sound1 according to the size or proportions of the whistle4 ,the annular opening a a is formed by the plate or cover1 a a1 which nearly fills the mouth of the cup ,b1 which is attached to the stem c4 ,the latter is screwed into the top1 ,d1 of the dome4 ,communication with the steam-space of the boiler is either opened or closed by a valve1 b1 which is attached to a sort of spindle1 d1 which extends upward inside of the stem c4 ,this spindle does not entirely fill the opening in the stem c1 so that the steam which enters when the valve b is opened rises and escapes through the holes e1 e1 e1 into the cup ,b and out through the annular opening a a4 ,the valve is opened by the lever ,e1 whose fulcrum is at f4 ,the end g of this lever is connected by a rod1 h1 figs4 #ha and #ga1 with the cab1 and by a suitable handle or lever1 h h1 fig4 #ga1 it can be opened and the whistle be blown at any time by the locomotive runner or fireman to give signals to the trainmen or of the approach of a train to a station1 or to warn persons to get off of the track4 ,illustration3 ,fig4 #ha4 ,scale #a in4 #a foot4 ,,question #aej4 ,how is a locomotive boiler emptied and cleaned8 ,answer4 ,one or two large cocks1 called blow-off cocks1 ,x1 fig4 #ga1 are placed near the bottom of the fire-box1 either in front or behind1 and sometimes on the side4 ,by opening either of these the water in the boiler is blown out1 and much of the loose mud and dirt is carried out with the water4 ,the cock ,x1 fig4 #ga1 is opened by a handle1 w1 which is connected with the cock by a rod4 ,in order to clean out the mud and scale which are not entirely loose1 what are called mud-holes or hand-holes are placed in the corners of the fire-box near the bottom4 ,these are oval-shaped holes1 about #d inches long and #b inches wide1 and covered with two metal plates1 one of which is put inside the boiler and the other outside1 and fastened with a bolt through both4 ,another hand-hole is sometimes placed in the bottom of the front tube-sheet4 ,when the boiler is emptied of water these hand-holes are uncovered1 and as much dirt is removed as can be scraped out of these holes4 ,a hose pipe is then inserted and a strong stream of water is forced in1 which washes out nearly all the loose dirt1 so as to leave the boiler comparatively clean4 ,when the water is very impure1 what is called a mud-drum1 ,m1 fig4 #da1 is used4 ,much of the mud and dirt is deposited in this receptacle1 from which it can easily be removed by taking off the cast-iron cover on the bottom of the drum4 ,the cover is also provided with a blow-off cock1 which is shown in the figure referred to4 ,,question #aea4 ,what other attachments are there to the boiler of a locomotive8 ,answer4 ,there are two cocks1 a1 a1 fig4 #ga1 called heater-cocks1 which are connected with pipes to the feed-pipes ,d ,d1 to admit steam to the latter to prevent the water in them from freezing4 ,there is also another cock1 b1 called a blower-cock1 which is connected to the smoke-stack by a pipe b1 b4 ,steam is conducted through this pipe and escapes up the chimney in a jet1 thus producing a draft when the engine is not working4 ,this arrangement is called a blower and is used to blow the fire when the engine is standing still4 ,the action of the jet is similar to that of the exhaust steam which escapes up the chimney1 excepting that the steam from the jet escapes in a continuous stream instead of distinct 8puffs10 as it does when it is liberated alternately from one end of the cylinders and then from the other4 ,t is a handle which is connected by a rod1 ,t ,t1 with the feed-cock 7not shown in the engraving7 in the pipe ,d4 ,this cock can be opened or closed by the handle1 and the supply of water fed into the boiler by the pump can thus be regulated4 ,j is a handle on the other side of the engine1 for regulating the working of the pump on that side4 e1 e are handles1 also connected by rods with the pet-cocks on the pumps4 ,these cocks can thus be opened or closed1 and it can then be known whether the pumps are working4 ,a is the furnace door1 which is fastened by a latch4 ,the latter has a chain1 ,q1 attached to it by which it can be conveniently opened or closed4 ,the door also has a circular register with six holes to admit air into the furnace4 ,these holes can be opened or closed by the revolving circular disc shown in the engraving4 ,illustration3 ,fig4 #hb4 ,scale in4 #a foot4 ,illustration3 ,fig4 #hc4 ,scale in4 #a foot4 ,illustration3 ,fig4 #hd4 ,scale in4 #a foot4 ,,question #aeb4 ,how are the grates constructed8 ,answer4 ,as has already been explained1 they are made usually of cast-iron bars1#dj ,a1 ,a1 ,a1 figs4 #hb and #hc1 called grate-bars4 ,fig4 #hb is a plan1 and fig4 #hc a horizontal section of one form of grate4 ,the bars in this kind of grate are usually cast in pairs1 or some times three or more are cast together4 ,they are made wider on the top than on the bottom edges1 as shown in the section1 fig4 #hc1 so that cinders and ashes will fall through easily1 and also to give free access to the air from below4 ,they are usually from to #a inches wide on the top1 and about inch on the lower edges4 ,the spaces between the bars are made from to #a inches wide4 ,for burning wood the bars are placed comparatively close together and are stationary1 but for burning bituminous coal they are usually made so that they can be moved1 in order to shake or stir up the fire1 just as is necessary in an ordinary stove or grate fire4 ,in the grate we have illustrated the bars1 ,a1 ,a1 are cast in pairs1 and run crosswise of the fire-box4 ,the ends are made with a sort of journals1 b1 b1 which rest on two supports1 ,b1 ,b1 called bearing bars1 which have suitable indentations to receive the ends of the grate-bars4 ,the latter have arms1 ,c1 ,c1 fig4 #hc1 cast on the under side1 to which a bar1 ,d ,d1 is attached4 ,by moving this bar back and forth1 the grate-bars have a rocking motion imparted to them1 as shown in fig4 #hd4 ,it is evident that in this way the fire over the whole surface of the grates will be disturbed or shaken4 ,the bar1 ,d ,d1 is moved by a lever1 m m1 shown in fig4 #ga4 ,an extension piece1 not shown in fig4 #ga1 is used with the lever m m1 so as to increase its length2 but it is removed after it has been used1 so as not to be in the way of the fireman4 ,grates which have movable bars are called shaking or rocking grates4 ,a great variety of such grates are made and in use1 to describe which would require more room than is available here4 #dj ,in ,europe and in some few cases in this country they are made of wrought iron4 ,for burning anthracite coal what are called water-grates are used4 ,these consist of wrought-iron tubes1 #b inches in diameter outside1 which are fastened in the front and back plates of the fire-box and are inclined upward from the front end1 so that there will be a continued circulation of water through them to keep them cool and thus prevent them from being burned out by the intense heat of the fire4 ,,question #aec4 ,how is the fire removed from the fire-box when it is necessary to do so8 ,answer4 ,in bituminous coal burning engines1 what is called a drop-door1 ,e ,e1 figs4 #hb1 #hc and #hd1 is provided for that purpose4 ,this door is supported partly on journals1 d1 d1 similar to those in the grate-bars1 on which it can turn1 and is held up or prevented from dropping by arms1 e1 e1 attached to a shaft1 ,f ,f4 ,this shaft is operated by a lever1 f f1 fig4 #hb1 outside the fire-box4 ,when the arms are in the position represented in fig4 #hc1 the drop-door is held up in the place in which it is shown2 but when they are turned as in fig4 #hd1 the door falls down so that the burning coal can be taken out of the opening at ,g1 and1 by raising up the ash-pan damper1 ,h1 fig4 #hd1 can be raked out on the track or into suitable pits usually provided for this purpose4 ,the drop-doors are sometimes perforated so as to admit air to the fuel on top of them4 ,the grates for burning anthracite coal usually have about four solid wrought-iron bars between that number of tubes4 ,these bars can be withdrawn1 and the fire then falls into the ash-pan through the opening left by the withdrawal of the tubes4 ,,question #aed4 ,how are the dampers of the ash-pan operated8 ,answer4 ,they are connected by suitable rods and levers with two handles1 l1 l1 fig4 #ga1 which are raised or lowered1 thus opening or closing the dampers4 ,,part ,,ix4 ,,the ,,throttle-,,valve ,,and ,,steam ,,pipes4 ,,question #aee4 ,how is the steam admitted to and the supply regulated or shut off from the cylinders8 ,answer4 ,by a valve1 h1 fig4 #da1 called a throttle-valve1 which is usually placed at the end of the pipe ,i1 near the top of the dome4 ,throttle-valves are sometimes placed in the smoke-box at the front end1 n1 fig4 #da1 of the dry-pipe4 ,until within a few years they consisted of plain slide-valves which covered openings similar in form to the steam-ports1 but smaller in size4 ,the pressure on such valves is of course greatest when there is no steam underneath1 which is the case when the valves are closed4 ,it is then very difficult to open them1 and as it is important that the supply of steam admitted to the cylinders when the locomotive is started should be easily regulated1 such valves are objectionable1 and therefore the form has been introduced which is illustrated in fig4 #da1 and also on a larger scale in fig4 #he1 which represents a longitudinal section of the throttle-pipe and valve4 ,this is what is called a double-poppet valve1 and consists of two circular discs1 a and b1 which cover two corresponding openings in the end of the pipe ,i4 ,when these discs are raised up1 as shown in fig4 #he1 steam flows in around their edges1 as represented by the darts4 ,it will be observed that the steam pressure in the boiler comes on top of the disc a and against the under side of b4 ,the pressure on the one thus neutralizes or balances that on the other4 ,if the two discs were of the same size1 the pressure of the one would be exactly the same as on the other2 but as they are joined together and are made to fit steam-tight on their seats by what are called countersunk joints1 their diameters must be somewhat larger than the openings they cover4 ,the only practicable way1 therefore1 by which the lower disc b can be introduced into the end h of the pipe ,i so as to cover the lower opening is through the upper opening a4 ,for this reason the lower disc must be made smaller than the upper one1 and therefore the pressure on the upper one1 being in proportion to its size1 has a constant tendency to close the valve4 ,as it is of the greatest importance that a throttle-valve should remain closed after steam is shut off1 and never be opened at any time accidentally1 the arrangement described accomplishes just what is needed--that is1 makes the valve work comparatively easily1 and at the same time keeps it closed after the steam has been shut off4 ,illustration3 ,fig4 #he4 ,scale in4 #a foot4 ,illustration3 ,fig4 #hf4 ,scale in4 #a foot4 ,,question #aef4 ,how is the valve opened and closed8 ,answer4 ,by a lever1 ,o ,o1 called a throttle-lever1 figs4 #he1 #hfda and #ga4 ,this lever is connected by a rod1 d1 called the throttle-stem1 with a bell crank1 i1 the other arm of which works the rod c1 to which the throttle-valve is attached4 ,the rod d works through a steam-tight stuffing-box1 f1 in the back end of the boiler4 ,the end of the throttle-lever is attached to two links1 g1 fig4 #hf1 which are fastened by a pin to the stud h4 ,these links have a slight vibratory motion1 which enables the pin k1 by which the lever ,o ,o1 is fastened to the rod d1 to move in a straight line1 which is necessary in order that the rod d may work steam-tight in the stuffing-box1 f4 ,the throttle-lever has a latch1 l1 which gears into a curved rack1 n1 so as to hold the lever and valve in any required position4 ,this latch is operated by a trigger1 m4 ,various other devices are used to fasten the throttle-lever and thus hold it in any position required4 #da ,fig4 #hf is a plan1 showing the top of the valve and lever4 ,,question #aeg4 ,how are the steam pipes constructed8 ,answer4 ,the steam1 after it is admitted by the throttle-valve1 as was explained in answer to ,question #aee1 passes into the throttle-pipe ,i and the dry-pipe m m1 fig4 #da4 ,at the front end of the dry-pipe a pipe1 n1 figs4 #dj and #da1 which divides into two branches like the top of the letter ,t and is therefore called a ,t-pipe1 is attached4 ,the steam-pipes o1 o1 fig4 #dj1 are connected to each of the two branches of the ,t-pipe at one end and to the cylinders at the other4#db #db ,in fig4 #dj the right-hand side represents a section through the steam-pipe o o1 and the left a section through the exhaust pipe e e4 ,illustration3 ,fig4 #hg4 ,scale #a in4 #a foot4 ,illustration3 ,fig4 #hh4 ,scale #a in4 #a foot4 ,these pipes1 being in the smoke-box1 are exposed to great changes of temperature1 and are therefore subjected to expansion by heat and contraction by cold4 ,the joints are therefore constantly subject to disturbance by the contraction and expansion of the pipes and so are difficult to keep tight4 ,it is also practically impossible to construct the boiler1 the cylinders and the pipes with perfect accuracy1 and therefore a small amount of adjustability and flexibility is necessary in the joints of the pipes4 ,if1 for example1 the opening x in the cylinder1 fig4 #dj1 were either too near or too far from the cylinder of the engine1 it would be necessary to move the end of the pipe o either to the right or to the left in order to connect it with x4 ,if the joint of the upper end of the steam-pipe were attached to the ,t-pipe with a flat joint like that shown at a b1 fig4 #hg1 it would be impossible to move the lower end of the steam-pipe either to the right or to the left without disturbing the joint and causing it to leak4 ,for this reason these pipes are connected with what are called ball joints1 fig4 #hh1 that is1 the end a b of one of the pipes is turned into the form of a part of a sphere1#dc and the other end into a corresponding concave form4 ,it is known that a sphere will fit into a corresponding socket in any position2 for example1 an acorn in its cup or the bones at the hip or shoulder joints4 ,if1 therefore1 the pipes are joined with such spherical or ball-joints as they are called1 the lower end can be moved sideways several inches either way1 and the joint will still be steam-tight if it is then firmly bolted together4 ,even after it is bolted together it will have so much flexibility that the expansion and contraction of the pipes will not cause it to leak4 #dc ,the dotted lines indicate what would be the form of the sphere if the pipe was solid instead of hollow4 ,there is1 however1 still another difficulty4 ,although the lower end of the pipe1 o o1 fig4 #dj1 can1 with a ball-joint above1 be moved in any direction horizontally1 yet if the pipe is too long or too short it is obvious such a joint will not permit it to be moved up or down4 ,a joint with a flat surface1 like that shown in fig4 #hg1 would1 however1 permit such motion in the pipe without leaking4 ,if1 for example1 the steam-pipe were of an inch too short1 it might be drawn down that distance1 and if the upper joint were then screwed up it would still be steam-tight4 ,in order1 then1 to get both vertical and lateral flexibility in the joints of the steam-pipes1 a ring1 a b1 fig4 #hi1 is interposed between the pipes4 ,one side of this ring is spherical and the other flat1 so that the pipes can move either around the spherical part or slip up or down or sideways on the flat surface of the ring4 ,in this way the pipes are flexible and adjustable in every direction1 and for all kinds of motion caused by expansion1 or which may be needed when the parts are put together4 ,sometimes the joints at one end only of the steam-pipes are made in this way1 and the other is connected with a simple ball-joint4 ,illustration3 ,fig4 #hi4 ,scale #a in4 #a foot4 ,in designing these joints their form should be drawn with a radius1 c d1 fig4 #hh1 from one centre1 c1 so that the surface of the joint will form a part of a sphere4 ,if they are drawn from two centres1 as is sometimes done1 it is obvious that the surface of the joint will not be a part of a sphere1 and therefore will not have the requisite flexibility4 ,the surfaces of the joints are carefully turned to the proper form1 and then made steam-tight by scraping or grinding them with emery and oil1 and the pipes are then fastened together with bolts1 g1 g1 fig4 #hi1 and flanges1 f1 f1 cast on the pipes4 ,,question #aeh4 ,how are the exhaust pipes constructed8 ,illustration3 ,fig4 #ij4 ,scale #a in4 #a foot4 ,answer4 ,they are made of cast iron4 ,when two nozzles are used they are generally cast together1 as shown in fig4 #ij4 ,when only one is used1 the form of the pipes resembles somewhat that of an inverted letter 1 as shown in fig4 #ia1 so as to cover the two openings which connect with the cylinders4 ,the tops of these pipes have rings or bushings1 a a1 fitted into them1 which are held by set screws1 b1 so that they can easily be removed and others with larger or smaller openings be substituted4 ,if the openings in the exhaust-nozzles are small1 the steam must be discharged at a higher rate of speed1 in order to exhaust all that is in the cylinders1 than if the blast orifices are larger4 ,therefore1 if the latter are reduced in size1 the draft becomes more violent1 but at the same time the back-pressure in the cylinder 7which will be explained hereafter7 is increased4 ,it therefore becomes necessary to adjust the size of the blast orifices with the greatest care1 so as to have them just small enough to produce the required draft and yet leave them as large as possible1 so as to reduce the back-pressure4 ,for these reasons what are called variable exhausts are sometimes used4 ,in these the blast orifice can be increased or diminished at pleasure1 and thus regulated to suit the conditions under which an engine is working4 ,a great variety of such devices has been used1 but now nearly all have been abandoned for the simpler arrangement described1 which is not variable when the engine is working4 ,illustration3 ,fig4 #ia4 ,scale #a in4 #a foot4 ,,part ,x4 ,,the ,,cylinders1 ,,pistons1 ,,guide-,,rods ,,and ,,connecting-,,rods4 ,,question #aei4 ,how are the steam cylinders constructed8 ,answer4 ,they are made of hard cast iron1 and have the steam and exhaust ports and valve-seats cast with them4 ,the harder the iron the better will the cylinders withstand the wear of the pistons and valves1 but they must at the same time be made soft enough1 so that after they are cast the inside can be bored out perfectly cylindrical1 the ends turned off1 the bolt-holes drilled1 and the valve-seats planed smooth4 ,fig4 #ib represents a longitudinal section through the centre of the cylinder and steam-chest4 ,fig4 #id is a plan of the same parts with the cover of the steam-chest and the valve removed4 ,the left-hand side of fig4 #ie shows a transverse section through the centre c d1 fig4 #ib1 of the cylinders1 and the right side is a section through the steam-pipe ,g h1 fig4 #id4 ,the same letters indicate like parts in the three different views4 ,the cylinders of locomotives in this country are now universally placed on the outside of the wheels1 as has already been described4 ,in order to fasten them securely together and to the boiler1 they are attached to what is called a bed-plate or bed-casting1 ,d ,d1 figs4 #id and #ie1 which is placed between them4 ,some builders make this bed-casting in a separate piece1 and the cylinders are then bolted to it on the outside1 about at the dotted lines1 l1 m1 fig4 #ie4 ,others cast one-half of it with each cylinder1 as shown in our engravings1 and then bolt them together at the line i1 j1 which is the centre of the engine4 ,the bed-casting is also bolted to the smoke-box by the flanges ,e1 ,e4 ,the cylinders are bolted to the frame ,f with bolts1 m and k1 fig4 #ie4 ,after the cylinders are bored out1 and the ends turned off1 heads1 ,a and ,b1 figs4 #ib and #id1 are fitted with steam-tight joints to each end4 ,these heads are fastened with bolts and nuts1 a1 a1 a1 to flanges1 ,c1 ,c4 ,,question #afj4 ,how is the steam conducted to and from the cylinders8 ,answer4 ,two pipes or passages are cast in each cylinder1 the one1 ,g ,g1 fig4 #ie1 for admitting steam into the steam-chest1 and the other1 ,h ,h1 for exhausting it from the cylinders4 ,the one ,g ,g is called the steam-passage1 and the other1 ,h ,h1 the exhaust-passage4 ,the steam-passage terminates at one end with a round opening1 ,g1 figs4 #id and #ie1 to which the steam-pipe o1 figs4 #dj and #ie1 is attached inside of the smoke-box4 ,at the other end it divides into two branches1 ,g1 ,g1 fig4 #id1 each of which terminates in an opening1 g1 g1 inside of the steam-chest4 ,the steam is thus delivered at both ends of the chest1 and can pass freely into each of the steam-ports4 ,by making the cylinders in this way1 they are exactly alike for each side of the engine1 or1 to use a shop phrase1 there are 8no rights and lefts10 so that a cylinder casting can be used for either side of the engine4 ,this method of making cylinders has been adopted by a number of the principal builders in this country1 but is by no means universal4 ,illustration3 ,fig4 #ib4 ,scale in4 #a foot4 ,illustration3 ,fig4 #ic4 ,illustration3 ,fig4 #id4 ,scale in4 #a foot4 ,illustration3 ,fig4 #ie4 ,scale in4 #a foot4 ,,question #afa4 ,how is the steam-chest constructed8 ,answer4 ,it usually consists of two castings1 one of which1 ,j1 figs4 #ib and #id1 is a square cast-iron box made open at the top and bottom4 ,this rests on the top of the cylinder casting and is joined to the latter with a steam-tight joint4 ,on top of it is a cast-iron cover1 ,k ,k4 ,the steam-chest and cover are held down by bolts1 p1 p1 which are screwed into the cylinder casting and have nuts on top4 ,,question #afb4 ,how are the slide-valves made to work steam-tight on the valve-seats8 ,answer4 ,they are first planed off smooth1 and then filed and scraped until the two touch each other over the whole of their surfaces in contact4 ,the valve-stem v1 fig4 #ib1 works steam-tight through a stuffing-box on the steam-chest4 ,,question #afc4 ,how are the valves and pistons oiled8 ,answer4 ,the oil is usually introduced into the steam-chest through a cock1 c1 fig4 #ib1 called an oil-cock4 ,from this cock it flows down upon the valve and is conducted by suitable holes and channels to the valve-face and from there through the steam-ports to the cylinder and piston4 ,sometimes1 for greater convenience1 oil-cocks c1 c1 fig4 #ga1 are placed inside of the cab and communicate by pipes with the steam-chests4 ,the valves are oiled by pouring oil or melted tallow into the oil-cocks when the steam is shut off from the steam-chests and cylinders4 ,when the pistons are working in the cylinders without steam1 they create a partial vacuum1 so that if oil is then poured into the oil-cocks it will be sucked into the steam-chests1 or1 in other words1 it will be forced in by the pressure of the air above it4 ,q1 fig4 #ga1 is a shelf attached to the boiler to receive an oil-can filled with oil or tallow1 which is thus melted or kept in a fluid condition by the heat of the boiler4 ,,question #afd4 ,how are the cylinders and steam-chests protected so as to prevent1 as far as possible1 the heat in the steam from being lost8 ,answer4 ,the sides of the cylinders are covered with wood1 w1 w1 w1 fig4 #ie1 called the cylinder lagging1 and the wood is covered outside with ,russia iron or brass1 which is called the cylinder-casing4 ,the ends of the cylinders have light metal covers1 called cylinder-head covers1 made of cast iron1 brass or sheet metal4 ,the steam-chest is covered in a similar way so as to be surrounded either with a covering of wood or of confined air4 ,sometimes coarse felt is used for the purpose4 ,the covering1 excepting the cylinder lagging1 is not shown in the engravings4 ,,question #afe4 ,for what purpose are the cocks ,c1 ,c1 figs4 #ib and #ie1 at each end of the cylinder1 used8 ,answer4 ,they are used to exhaust the water which collects in the cylinders4 ,when the engine is not working the cylinders and steam-pipes are all cooled off1 so that when steam is first introduced into them a great deal of it is condensed until they become warmed4 ,water is also frequently carried over from the boiler with the steam4 ,when this occurs the boiler is said to prime1 or to 8work water40 ,this water and that produced by the condensation of steam collect in the bottom of the cylinder and will not escape through the exhaust-pipes until the piston moves up so near to the end of the cylinder that the water will fill the whole space between it and the cylinder-head4 ,as has already been stated1 it will then escape so slowly that the momentum of the piston and other machinery is liable to 8knock out0 the cylinder-heads or even break the cylinder itself4 ,the cocks ,c1 ,c1 called cylinder-cocks1 are therefore placed in the under side of the cylinder1 so that when they are open if there is any water in the cylinder it will escape through the cocks4 ,they are therefore always opened when the engine is starting1 or at any other time when there is any indication that there is water in the cylinders4 ,,question #aff4 ,how are these cocks opened and closed8 ,answer4 ,a shaft1 ,r ,r1 figs4 #ib and #id1 which extends across the frames1 has an arm1 ,r ,s1 fig4 #ib1 at each end4 ,these arms are connected by rods1 ,s ,t1 with the handles of the cylinder-cocks4 ,the shaft also has a vertical arm1 ,r ,u1 the upper end of which is connected by a rod with the cab4 ,at the end of the rod is a suitable handle1 f1 fig4 #ga1 by which the cocks can be either opened or closed at pleasure by the locomotive runner4 ,,question #afg4 ,how is the piston-rod fastened to the piston8 ,answer4 ,it fits into a straight or tapered hole in the piston-head1 in which it is fastened either with a key1 k k1 as shown in figs4 #if and #ig1dd or by a nut on the front side of the piston4 #dd ,fig4 #if is an end view of the piston with the follower-plate removed4 ,fig4 #ig is a section through the centre4 ,illustration3 ,fig4 #if4 ,illustration3 ,fig4 #ig4 ,scale #a in4 #a foot4 ,,question #afh4 ,how is the piston constructed8 ,answer4 ,it is made of two cast-iron pieces1 ,b and ,c1 fig4 #ig1 the one1 ,b1 called the piston-head or spider1 to which the piston-rod ,d is attached4 ,the other part1 ,c1 called the follower-plate1 is bolted to the piston-head by the bolts c1 c1 called follower-bolts4 ,the piston-head has lugs or projections1 d1 d1 d1 fig4 #if1 cast on the inside1 to which the follower plate is bolted4 ,hollow spaces are thus left between these lugs4 ,,question #afi4 ,how is the piston made to work steam-tight in the cylinder8 ,answer4 ,by means of two rings1 ,a1 ,a1 figs4 #if and #ig1 called packing-rings4 ,these rings are turned of the same size or a little larger in diameter than the cylinder4 ,they are then cut open at one point in their circumference so that they can be pressed apart or expanded by the springs a1 a1 called packing springs1 on the inside of the rings4 ,these springs are pressed out by the nuts and bolts b1 b1 called packing-bolts and packing-nuts1 so that when the rings wear they can be expanded so as to fill the cylinder completely4 ,the place where the one ring is cut is placed opposite that of the opening in the other ring1 or they are made to break joints1 as it is called4 ,this is done to prevent the steam which leaks through the opening where the one ring is cut from passing through to the other side of the piston4 ,these rings are usually made of brass and have grooves1 c1 c1 fig4 #ig1 turned in them1 which are filled with what is called ,babbitt's metal4 ,this metal is used because it is less liable to scratch the cylinders than brass alone4 ,another ring1 l l1 made of cast iron and as wide as the two brass rings1 is placed inside of the latter and is intended to furnish a bearing for the springs1 and thus distribute the pressure of the springs equally on the packing rings4 ,this iron ring is also cut open at one point4 ,,question #agj4 ,how is the piston-rod made to work steam-tight through the cylinder-head8 ,answer4 ,by what is called a stuffing-box4 ,this consists of a cylindrical chamber1 r r1 fig4 #ib1 which is made about #a inches larger in diameter than the piston-rod4 ,this leaves a space of an inch wide all around the rod4 ,this space is filled with hemp or some other fibrous material1 called packing1 saturated with oil or melted tallow4 ,this packing is compressed by a hollow cylinder1 s s1 called a gland1 the inside of which fits the piston-rod and the outside the stuffing-box4 ,this gland is forced into the stuffing-box by nuts1 t1 t1 which are screwed down on a flange1 u1 attached to the gland4 ,the packing is thus compressed in the stuffing-box and forced against the piston-rod1 which is made smooth and perfectly round and straight1 and against the side of the stuffing-box1 so that no steam can escape around the piston-rod4 ,a brass ring or 8bushing0 is often put into the cylinder-head and in the gland where it touches the piston-rod1#de because brass will bear the friction of the rod better than cast iron1 and when it is worn out it can be removed and a new one substituted in its place4 #de ,locomotive piston-rods are now usually made of steel4 ,,question #aga4 ,why is the end of the piston-rod made to work in guides8 ,answer4 ,because it must move in a straight line if it and the piston work steam-tight in the cylinder4 ,by referring back to fig4 #b1 it is obvious that if a pressure be exerted against the piston ,b and communicated to the crank-pin ,n by the connecting-rod ,e1 the latter1 excepting at the dead-points1 will exert a pressure either upward or downward1 according to the direction the piston is moving4 ,this pressure would bend the piston-rod if no provision were made to prevent it4 ,for this reason1 therefore1 the end of the piston-rod is attached to what is called a cross-head1 ,l1 figs4 #ib and #id1 which works in guides1 ,m1 ,m4 ,the cross-head is made of cast iron and has slides1 ,n1 ,n1 figs4 #ic and #id1 one on each side1 each of which works between a pair of guide-bars or rods1 ,m1 ,m1 shown in section in fig4 #ic4df ,these guide-rods1 or guides as they are called1 are planed and finished with great accuracy so as to be straight and smooth1 and are attached to the cylinder-head at one end1 and to a support1 ,o1 called the guide-yoke1 which is fastened to the frame at ,f1 fig4 #id1 and also usually attached to the boiler4 ,the guides are set with great care1 so as to be exactly parallel with the axis or centre line of the cylinder1 so that the cross-head will slide in exactly the same path that the piston-rod will if it moves in a straight line4 ,if then the piston-rod and the connecting-rod are attached to the cross-head1 all the strain produced by the obliquity of the connecting-rod will be borne by the guides1 thus relieving the piston-rod1 and making it certain that it will move in a straight line4 #df ,fig4 #ic is a transverse section through the guides at n1 fig4 #ib4 ,,question #agb4 ,how are the piston and connecting-rods attached to the cross-head8 ,answer4 ,the end of the piston-rod fits into a tapered hole in the cross-head and is held by a key1 w1 figs4 #ib and #id4 ,the connecting-rod is attached to a pin1 ,q1 called a wrist-pin1 which is cast with the cross-head4 ,,question #agc4 ,how is the wear of the slides lessened and compensated8 ,answer4 ,sometimes they are made with brass wearing pieces called gibs1 shown at ,n1 ,n1 fig4 #ic1 which are placed between the slides and the guides4 ,these gibs can either be removed and new ones substituted when they become very much worn1 or by inserting thin pieces of metal1 called liners1 between them and the cross-head1 they will be spread apart so as to fill the space between the slides4 ,the slides are now1 however1 oftener made without gibs1 and have recesses either cast or drilled in them1 which are filled with either ,babbitt's metal or glass bearings1 which latter are said to wear very well4 ,the guides are bolted at each end to blocks1 x1 x1 called guide-blocks1 which can be planed off so as to bring the guides nearer together when they and the slides are worn4 ,sometimes liners are placed between the blocks and the guides1 which can be removed when it is necessary to bring the guides nearer together4 ,,question #agd4 ,are the top and bottom guides worn alike8 ,answer4 ,no3 the top guide in ordinary engines is worn the most1 because the pressure of the slides is always on the top guide when the engine is running forward1 and on the bottom guide when it is running backward4 ,this will be understood by referring back to the series of figures from #aa to #bd4 ,it will be noticed that in the backward stroke of the piston1 represented by figs4 #aa to #ag1 the strain on the connecting-rod tends to push the cross-head upward1 and in the forward part of the stroke1 figs4 #ah to #bd1 the connecting rod pulls the cross-head in the same direction4 ,if the crank turned the opposite way1 this action would be reversed and the cross-head would then be alternately pushed and pulled downward1 and the bottom guides would then be worn the most4 ,as nearly all locomotives run forward more than backward1 the top guides are usually worn the most4 ,,question #age4 ,how are the slides oiled8 ,answer4 ,oil cups1 n1 o1 figs4 #ib1 #ic and #id1 are placed about the middle of the top guide4 ,these cups usually have a reservoir to hold a supply of oil1 and are so constructed that it will be gradually fed on the slides1 which are thus constantly and regularly lubricated4 ,,question #agf4 ,how are the pumps worked from the piston-rods8 ,answer4 ,the pump-plunger is attached to a projection1 ,w1 figs4 #ib and #ic1 called the pump-lug1 cast on one of the slides of the cross-head4 ,the plunger thus receives a reciprocating motion from the piston4 ,,question #agg4 ,how are the connecting-rods made8 ,answer4 ,they are made of flat bars of wrought iron4 ,the rods which connect the cross-heads with the driving-wheels are called main connecting-rods1 and the rods which connect or couple the driving-wheels together are called coupling-rods4#dg ,fig4 #ih represents a side view and a plan of a main connecting-rod4 ,in the side view the end ,b1 and in the plan both ends of the rod are shown in section4 ,it is attached to the wrist-pin at ,a and to the crank-pin at ,b4 ,fig4 #ii represents similar views of a coupling-rod4 ,to save room in the engraving each of these rods is represented with a part of the middle broken away4 ,the main rods are usually made wider at ,g1 next the crank-pin1 than at the other end1 as it has been found that they are most liable to break at that end4 ,the coupling-rods are now made either straight or somewhat wider in the centre4 #dg ,they are also often called side or parallel-rods1 but the term coupling-rods is considered the best4 ,illustration3 ,fig4 #ih4 ,illustration3 ,fig4 #ii4 ,scale in4 #a foot4 ,,question #agh4 ,how are these rods prevented from getting loose on the pins from the wear of the latter in the inside of the holes of the rods8 ,answer4 ,the ends of the rods are provided with what are called brass-bearings1#dh or 8brasses10 c1 d1 and e1 f4 ,these brasses are made in pairs1 so as to embrace the pins1 from each side4 ,they are held by -shaped clamps1 s s s1 called straps1 which are bolted to the rods4 ,when the brass-bearings become worn1 they are taken out of the straps1 and a portion of their surfaces of contact with each other is filed away1 thus allowing them to come nearer together1 and thereby reducing the size of the hole which receives the pin or journal4 ,in order to prevent their being loose in the straps1 tapered or wedge-shaped keys1 k1 k1 which bear against the brasses1 are fitted in the straps and rods4 ,by driving down these keys the brass bearings are forced together1 thus reducing the size of the hole for the journal1 and making the rods fit tightly on the pins4 ,a hard steel plate1 shown by dark shading in the engraving1 is sometimes interposed between the keys and the brasses to prevent the key from indenting the surface of the soft brass4 ,as the keys are very liable to get loose and fall out1 they are held either by screws and nuts1 x1 x1 as shown in the engraving1 or by set-screws on the side of the rods4 ,the whole arrangement of straps1 keys and brasses is called a stub-end4 #dh ,the portion of a shaft pin or spindle subjected to friction is called a journal1 and the surface which presses or 8bears0 against it is called a bearing4 ,,question #agi4 ,how are the journals of the crank-pins oiled8 ,answer4 ,by oil-cups attached to the straps1 above the journals1 similar to the cups used on the guide-rods1 but which are not shown in the engravings of the connecting-rods4 ,sometimes oil-cellars1 as they are called1 are attached to the under side of the straps4 ,these are metal boxes1 which are filled with oil1 which is agitated violently by the rapid motion of the rods1 and is thus applied to the journals through holes drilled in the straps4 ,in order to confine the oil and prevent its leaking out around the journals of the coupling-rods1 the brasses at n1 n1 fig4 #ii1 are usually made so as to enclose the outside end of the crank-pin1 which thus not only keeps the oil in1 but excludes the dust4 ,the brasses are usually lined with ,babbitt's or some other kind of soft metal1 which is thought to be less liable to heat from the friction of the journals4 ,,question #ahj4 ,are the coupling-rods always made with stub-ends8 ,answer4 ,no2 their ends are sometimes made in one piece--that is1 without straps or keys4 ,the holes which receive the crank-pins then have brass rings or bushings1 as they are called1 which fit tightly and are driven into the holes1 and form the bearings on the pins4 ,when these rings become worn they are driven out and new ones put in4 ,,question #aha4 ,what is meant by the term lost motion8 ,answer4 ,it is used to designate the wear of machinery1 which causes a loss of motion in some of the parts4 ,thus if the bearings of the main connecting-rods are worn1 the piston must move a distance equal to the wear at each end of the stroke before it moves the crank-pin4 ,lost motion might therefore be called the looseness of the parts4 ,when we speak of taking up the lost motion1 we mean making parts which were loose fit tightly4 ,,part ,,xi4 ,,the ,,valve-,,gear4 ,,question #ahb4 ,what is meant by the valve-gear of a locomotive8 ,answer4 ,by the valve-gear is meant the arrangement of eccentrics1 rods1 links1 rockers1 etc41 by which the valves are moved and their motion regulated4 ,,question #ahc4 ,what is required of the valve-gear in working a locomotive8 ,answer4 ,it must be so arranged that the locomotive can be run either backward or forward1 and so that the motion of the wheels can be reversed quickly and with certainty4 ,it should enable the runner to employ the greatest power of the engine by admitting steam into the cylinders during the whole or nearly the whole of the stroke of the pistons1 or when less power is required1 to use the steam more economically by working it expansively1 which latter is accomplished with the present appliances by changing the travel of the valve4 ,,question #ahd4 ,how is the valve-gear constructed so as to run the engine either backward or forward8 ,answer4 ,as already explained1 in answer to question #gf1 two eccentrics are provided for each cylinder4 ,these are set so that one of each pair will run the locomotive in one direction1 and the other two the reverse way4 ,,question #ahe4 ,how must the eccentrics for each cylinder be set in order that the one may run the engine forward and the other backward8 ,answer4 ,this can be best explained by reference to fig4 #ajj1 in which the piston1 ,p1 is represented at the beginning of the backward stroke1 and the valve ,v has the requisite lead and is just about to open the front steam-port4 ,it is obvious that1 in order to complete the backward stroke of the piston1 the front port must be opened to admit steam into the front end of the cylinder1 and therefore the valve must be moved in the direction indicated by the dart a4 ,to do this1 the upper arm of the rocker r must move in the same direction1 and the lower arm must be moved the reverse way1 as indicated by the dart e4 ,if the crank is intended to move in the direction indicated by the dart ,n1 then the centre of the eccentric must be above the centre of the shaft or axle1 in order to move the rocker in the direction indicated by the dart e4 ,supposing1 however1 it was intended to move the crank the reverse direction1 as shown by the dart ,n in fig4 #aja2 it is evident in that case that the valve must be moved in the same direction as before1 in order to open the front steam-port and thus admit steam to force the piston back4 ,but if the crank turns in the direction shown by the dart ,n1 fig4 #aja1 then the centre of the eccentric must be placed below the centre of the axle in order to move the lower rocker arm in the direction of the dart e and the valve in that indicated by a4 ,it will thus be seen that the centres of the eccentric for running forward and that of the one for running backward must be placed1 the one above and the other below the centre of the axle at the beginning of the stroke of the piston1 as shown in figure #aja4 ,illustration3 ,fig4 #ajj4 ,fig4 #aja4 ,fig4 #ajb4 ,scale in4 #a foot4 ,,question #ahf4 ,why is it that the centres of the eccentrics are not placed opposite to each other on the axle8 ,answer4 ,because before the beginning of the stroke of the piston it is necessary to move the valve from its middle position a distance equal to the lap before the steam-port begins to open4 ,if we have a valve like that shown in fig4 #aj--that is1 without any lap--the centres of the eccentrics could be placed at right angles1 or1 as mechanics say1 8square0 with the crank1 as was shown in fig4 #aa1 and exactly opposite to each other1 because such a valve begins to take steam as soon as it moves from the middle of the valve-face4 ,if1 however1 we have a valve like that shown in fig4 #bg1 it is plain that before it will admit or take steam1 as it is called1 in either of the steam-ports1 it must be moved from the centre of the valve-face1 or its middle position1 a distance equal to the lap1 ,l4 ,for this reason1 therefore1 the eccentric1 instead of being placed at half-throw1#di as it is called1 must be so far ahead of the middle position as to have moved the valve a distance equal to the lap1 and if any lead is given to the valve1 equal to the lap and lead together4 ,in figs4 #ajj and #aja1 f g is a vertical line at right angles to the crank at the beginning of the stroke4 ,it will be seen that the centre of each of the eccentrics is set far enough ahead of this line to give the valve the required lead4 ,when the piston reaches the back end of the cylinder1 the two eccentrics will occupy the position shown in fig4 #ajb1 in which position the lower one would move the valve so as to turn the crank in the direction of the dart ,n1 and the upper one in the reverse direction4 ,it will be seen that in this position both of the eccentrics are again ahead of half-throw1 when the piston is at that end of its stroke4 #di ,this would be at right angles to the crank when the piston is at the end of the stroke4 ,illustration3 ,fig4 #ajc4 ,scale in4 #a foot4 ,,question #ahg4 ,how is the motion of either eccentric communicated to the valve8 ,answer4 ,the ends of each pair of eccentric-rods are connected together by a link1 a b1 fig4 #ajc4 ,this link has a curved groove or slot1 a b1 in it1 in which a block1 ,b1 fits accurately1 so that it can slide freely from one end to the other4 ,this block is attached to the lower rocker-arm by a pin1 c1 which works freely in the block4 ,the two eccentric-rods ,c and ,d are attached to the ends of the link at e and f by pins and knuckle-joints4 ,it is apparent that if the link is down1 or in the position shown in fig4 #ajc and also on a smaller scale in fig4 #ajd1 the motion of the upper eccentric-rod1 which is usually used for the forward motion1 will be imparted to the rocker1 and thus to the valve1 and when the link is in the position shown in fig4 #aje1 that the valve will be moved by the lower or backward eccentric-rod ,b4 ,in order to reverse the engine1 it is then only necessary to provide the means of raising and lowering the links4 ,this is done by a shaft1 ,a1 fig4 #ajc1 called a lifting-shaft1 which has two horizontal arms1 ,e1#ej one for each link1 and a vertical arm1 ,f4 ,the links are suspended from the ends of the horizontal arms by rods or bars1 g h1 called link-hangers1 which are connected to the links and to the arms above by pins1 which enable the hangers to vibrate freely4 ,the lower pin is attached to a plate1 ,l d1 called a link-saddle1 which is bolted to the link4 ,the vertical arm of the lifting-shaft is connected by a rod1 ,g ,g1 called the reverse-rod1 to a lever ,o1 ,o1 ,plate ,,ii4 in the cab called a reverse-lever1 the construction of which will be explained hereafter4 ,this lever is worked by the locomotive runner1 and by moving the upper end of it forward1 the link will be lowered1 and the rocker and valve will be moved by the forward eccentric2 and if the reverse-lever is moved back1 the link will be raised1 and the backward eccentric will move the valve4 ,when this is done1 the valve-gear is said to be thrown into the forward or backward motion1 or forward or back gear4 #ej ,only one of these is shown in the engraving4 ,illustration3 ,fig4 #ajd4 ,fig4 #aje4 ,scale1 inch #a foot4 ,illustration3 ,fig4 #ajf4 ,fig4 #ajg4 ,scale1 inch #a foot4 ,,question #ahh4 ,how is the travel of the valve changed by the motion of the link8 ,answer4 ,by either raising or lowering the link1 so that the link-block and rocker-pin will be some distance above or below the eccentric-rods4 ,thus in fig4 #ajd1 the motion of the upper eccentric-rod1 and in fig4 #aje that of the lower or back eccentric-rod is communicated to the rocker-pin and the valve4 ,if1 however1 the link should be raised so that the link-block and rocker-pin are somewhat below the upper or forward eccentric-rod1 as shown in fig4 #ajf1 then the motion imparted to the rocker and valve will partake somewhat of that of the upper and also of the lower eccentric-rod4 ,so long as the rocker-pin is above the centre of the link1 the motion of the valve will partake most of that of the upper or forward rod1 and the engine will then run forward1 but when the rocker-pin is below the centre of the link1 its motion will be influenced more by the back eccentric-rod1 and the engine will then run backward4 ,the motion of the link1 which is somewhat complex and difficult to understand clearly1 will perhaps be understood better if we represent it in a number of successive positions of the whole stroke of the piston1 as was done to show the motion of the eccentric in figs4 #aa to #bd4 ,we will therefore suppose that the link is in what is called full gear forward1 as shown in figs4 #ajc and #ajd4 ,in fig4 #ajh the link is in the position it would occupy at the beginning of the stroke of the piston2 in fig4 #aji it is in that which it will be in when the piston has moved four inches2 in fig4 #aaj1 when it has moved eight inches2 in fig4 #aaa1 twelve2 and in figs4 #aab1 #aac and #aad1 sixteen1 twenty and twenty-four inches4 ,figs4 #aad to #aai represent the successive positions of the link during the return stroke4 ,in order to show the different positions of the link we have represented on a larger scale1 in fig4 #abj1 the successive positions of the centre line of the link1 which will indicate the motion imparted by it to the rocker4 ,in order to designate each of these positions1 the centre lines in fig4 #abj are numbered and -#j1 #d1 #h1 etc41 etc41 to correspond with similar numbers in figs4 #ajh to #aai4 ,illustration3 ,fig4 #ajh4 ,fig4 #aji4 ,fig4 #aaj4 ,fig4 #aaa4 ,fig4 #aab4 ,fig4 #aac4 ,illustration3 ,fig4 #aai4 ,fig4 #aah4 ,fig4 #aag4 ,fig4 #aaf4 ,fig4 #aae4 ,fig4 #aad4 ,scale in4 #a foot4 ,illustration3 ,fig4 #abj4 ,scale in4 #a inch4 ,illustration3 ,fig4 #aba4 ,scale in4 #a inch4 ,illustration3 ,fig4 #abb4 ,scale in4 #a inch4 ,thus the line -#j -#j represents the position of the centre of the link which it occupies at the beginning of the stroke as shown in fig4 #ajh4 ,the line -#d -#d1 that represented by fig4 #aji1 when the piston has moved #d in4 ,the lines -#h -#h1 -#ab -#ab1 -#af -#af1 -#bj -#bj1 #bd #bd1 #d #d1 etc41 the successive positions of the centre of the link represented in figs4 #ajh to #aai4 ,the dotted lines h a and h b represent the two extreme positions into which the rocker-arm would be moved by the action of the link4 ,it will be seen that when the link is in the position shown1 it imparts the full stroke of the eccentrics to the rocker-pin and consequently to the valve4 ,we will now suppose that the link is raised up as shown in fig4 #ajf1 so that the position of the rocker-pin is just half-way between the end of the eccentric-rod and the centre of the link4 ,this position is called half-gear4 ,in fig4 #aba the different positions of the centre line of the link and of the rocker have been laid out for half-gear in the same way as was done for full-gear before4 ,from this it will be seen that the travel1 a b1 imparted to the rocker-pin and valve by the link when it is in the position shown1 instead of being #e in4 is only #c in4 ,in fig4 #ajg the link is raised up1 so that the rocker-pin is in the centre of it or midway between the eccentrics4 ,this position is called mid-gear4 ,the successive positions of the centre line of the link in this position have been laid down in fig4 #abb in the same way as was done for full and half-gear4 ,the movement of the rocker1 it will be seen1 is1 for mid-gear1 only #b in4 ,these diagrams show that when the rocker-pin is opposite the eccentric-rod1 the valve receives the full throw of the eccentric1 and that the motion imparted by the eccentric diminishes as the rocker-pin approaches the centre of the link1 so that1 with eccentrics having #e in4 throw and a valve with lap and in4 lead1 we can increase or diminish the travel of the valve from #b to #e in4 by simply raising or lowering the link1 which is done by the reverse-lever4 ,,question #ahi4 ,what is the effect of this variation of travel on the working of the valve and the admission and release of steam to and from the cylinder8 ,answer4 ,it is almost precisely the same as that which is effected by increasing or diminishing the throw of the eccentric1 which was explained in the answer to ,question #eb4 ,in order to show this effect more clearly1 we have represented by motion-curves1#ea fig4 #abc1 the movement imparted to the valve by the link when it is in full1 half and mid-gear1 as illustrated in the preceding figures4 ,the curve for full-gear is engraved in full heavy lines2 that for half-gear in lighter lines1 and for mid-gear in dotted lines4 ,from these curves it will be seen that when the valve is worked in full-gear the steam-port is opened wide at #b in4 of the stroke and steam cut off at #ba inches4 ,when the valve is worked in half-gear the port is not at any time opened wide and steam is then cut off at #ag in4 of the stroke1 and when worked in mid-gear the greatest opening of the steam-port is no greater than the lead and the cut-off occurs at #d inches of the stroke4 #ea ,the nature of these curves was explained in answer to ,question #dd4 ,it is of course possible to work the link in any intermediate position between those which we have represented4 ,usually the reverse-lever is arranged so that the steam will be cut off at #f1 #h1 #aj1 #ab1 #ae1 #ah1 and #bj inches of the stroke4 ,,question #aij4 ,what is the greatest and the least admission of steam possible with the ordinary link motion8 ,answer4 ,with #bd in4 stroke of piston and #e in4 travel and in4 lap1 steam can be admitted as shown by the motion-curves during #ba in4 or #hg per cent4 of the stroke1 and can be cut off at about #d in4 or #af per cent4 ,it will be seen1 however1 that in mid-gear the motion-curve becomes a straight line1 and that the pre-admission of steam1 that is the admission of steam before the piston reaches the end of the stroke1 is equal to that admitted after1 so that it is impossible to work the locomotive with the link in that position4 ,practically it is found that no useful work can be done with a link if the steam is cut off at less than six inches1 or one-fourth of the stroke4 ,even then the opening of the steam-ports is so small that the steam which enters the cylinders is very much wire-drawn4 ,,question #aia4 ,how are the curves drawn which represent the motion of the valve8 ,answer4 ,these motion-curves as produced by the link-motion are very difficult to draw1 as the motion of the link is extremely complicated4 ,it is doubtful1 therefore1 whether those who have no knowledge of mechanical drawing will be able to understand the following description of the method of doing it1 which we will try to make as clear as possible4 ,illustration3 ,fig4 #abc4 ,scale in4 #a inch4 ,illustration3 ,fig4 #abd4 ,scale in4 #a foot4 ,in the first place1 the centre ,s1 fig4 #abd1 of the axle1 ,a1 of the rocker1 and ,b of the lifting-shaft1 must be laid down in their proper positions4 ,if1 now1 the valve has in4 lap and lead1 the lower rocker-pin must be one inch ahead of its middle position when the piston is at the front end of the cylinder1 and at the beginning of the backward stroke4 ,we will1 therefore1 mark the centre1 a1 of the rocker-pin in this position4 ,if from the centre of the axle a circle1 c d e1 be drawn whose diameter is equal to the throw of the eccentrics1 this circle will represent the path in which the centres of the eccentrics will revolve4 ,if1 now1 the distance from the centre of the axle to the centre of the lower rocker-pin1 a1 when the latter is in its middle position1 be taken for a radius1#eb and from the position of the rocker-pin at the beginning of the stroke as a centre1 the circle representing the path of the eccentrics be intersected at two points1 c and d1 the points of intersection will represent the positions of the centres of the forward and backward eccentrics4 ,having determined these positions1 draw arcs of circles1 f and g1 from these centres with a radius equal to the distance from the centres of the eccentrics to the centres of the pins which connect the rods to the link4 ,it is evident that at the beginning of the stroke the centres of the pins in the link must each be in one of these arcs4 ,but the link is suspended by the hanger1 i h1 which oscillates from the end1 i1 of the lifting-arm1 which for any one point of cut-off is stationary2 and therefore the point of suspension of the link must always be in the arc1 j k1 described from the centre of the pin1 i1 in the lifting-arm1 with a radius equal to the length of the hanger4 ,there are1 therefore1 three points in the link1 each of which must be in one of the arcs which have been drawn1 and which will determine the position of the link4 ,this can be done easiest by drawing the link1 ,l1 fig4 #abe1 on a stiff piece of paper1 m n1 and cutting off the back1 p q1 of it through the centres of the pins1 s and t1 and also cutting out a triangular piece1 u1 the apex of which will correspond with the centre of the point of suspension1 o4 ,by placing this piece of paper on the drawing it can be moved1 so that the three centre points1 s1 t and o1 will respectively conform with the arcs1 f g and j k1 fig4 #abd4 ,in this position the piece of paper will then be in the position of the link for the point of the stroke represented4 ,by marking the centres of the link-pins on the arcs f and g1 and from them as centres1 with the length of the rods used to draw the arcs1 two other arcs1 v1 w1 be drawn intersecting each other1 the point d1 where they intersect will be the centre from which the centre line of the link can be drawn with a radius1 l d1 equal to the distance from the centre of the eccentrics to the centre of the link4 ,this will give the first position -o -o1 of the centre line of the link4 ,as the rocker-pin must always be in the centre of the link1 it is obvious that the point at which the centre-line of the link intersects the arc in which the rocker-pin oscillates must be the position of the centre of the rocker-pin4 ,with this determined the position of the valve can easily be located4 #eb ,this is usually the radius of the link but in some cases either a longer or shorter radius is taken to draw the link4 ,in the following explanation it is assumed that the link is drawn with this radius1 or from the centre of the axle4 ,of course if a greater or lesser radius is used1 due allowance must be made therefor4 ,illustration3 ,fig4 #abe4 ,scale1 in4 #a foot4 ,in order to represent the link at any other point of the stroke1 say after the piston has moved four inches1 the position of the crank must first be laid down4 ,to do this1 allowance must be made for the irregularity due to the angularity of the connecting-rod1 which was explained in answer to ,question #ed4 ,from the centre of the axle1 a circle1 ,c ,d1 whose diameter is equal to the stroke of the piston1 is first drawn1 which will represent the path of the crank-pin4 ,a horizontal centre line1 ,e ,f1 should also be drawn through the centre of the axle and the centre of the cylinder4 ,the intersection o of this line with the path of the crank-pin will be the position of the latter at the beginning of the stroke4 ,if from this point a distance1 o o1 be laid off on the centre line equal to the length of the connecting-rod1#ec it will give the position of the wrist-pin at the beginning of the stroke1 so that from this its successive positions for each inch of the stroke can be laid off4 ,from its position after the piston has made say four inches of the stroke as a centre1 and the length of the connecting-rod as a radius1 if the path of the crank-pin be intersected at -#d1 the point of intersection will represent the position of the crank-pin at four inches of the stroke4 ,the distance from o to -#d is equal to #dd degrees of the whole circle4 ,the eccentrics1 being attached to the axle1 of course move the same number of degrees that the crank does1 and therefore1 in order to determine their position when the crank has moved any distance1 it is only necessary to move them as many degrees as the crank has4 ,this can be done very easily by extending the radii of the eccentrics1 when they are in the first position1 until they intersect the path of the crank-pin at c and d4 ,by stepping off from the latter points of intersection a distance c c and d d1 equal to o -#d1 which the crank has moved1 and then drawing other radii from the two points c1 d1 their intersection1 c d1 with the path of the eccentrics will represent the position of the centres of the eccentrics when the crank is at -#d4 ,having determined the position of the eccentrics1 the link can be laid down as before1 that is1 from c and d as centres and with the length of the eccentric-rods as a radius arcs1 f and g1 are drawn4 ,then with the paper template the positions of the centres of the link-pins in these arcs are determined and marked1 and from them with the length of the eccentric rods as a radius1 two intersecting arcs1 v1 w1 are drawn1 whose intersection gives the centre of the link from which its centre line1 -#d -#d1 is drawn4 ,this will give the position of the rocker-pin for another point of the stroke4 ,in a similar manner its position can be determined for any number of points of the stroke1 from which the position of the valve can easily be determined and laid down on the diagram for the motion-curve as was described in the answer to ,question #dd4 ,of course the valve will be moved from its middle position the same distance that the rocker-pin is1#ed only in an opposite direction4 ,in order to lay down the position of the valve on the diagram for motion-curves1 it is1 therefore1 only necessary to draw it in the same relative position as that of the rocker-pin which is given by the point of intersection of the center line of the link with the path in which the rocker-pin oscillates4 ,to construct the motion-curves it is necessary to determine the positions of the valve for different points of the stroke and mark them on the horizontal lines which represent the respective positions of the piston4 ,curves are then drawn through these points1 either by hand or by constructing templates4 ,the more points there are determined1 the more accurate will be the curves4 ,it is1 therefore1 best to lay down the position of the valve for each inch of the stroke of the piston4 ,they should also be drawn full size1 which of course was impossible for the illustrations which are given herewith4 #ec ,in order to get the engraving within the required limits1 the diagram is drawn with a connecting-rod only #e instead of #g feet4 ,the latter is the length used in previous illustrations4 #ed ,this will be the case when the two arms of the rocker are of the same length1 as they usually are4 ,sometimes1 though rarely1 they are of different lengths4 ,,question #aib4 ,is there any other method of drawing these motion curves8 ,answer4 ,yes3 models which show the working of the valve-gear have been constructed with a pencil1 to which the reciprocating motion of the valve is imparted1 and which traces a curve on a surface having the same motion as the piston4 ,this method has been employed by the writer in an instrument which he has applied to the locomotive itself4 ,the principle upon which it works will be understood by supposing that the steam and exhaust-ports as represented in the diagram for motion-curves1 fig4 #abc1 be drawn on a board1 ,a ,b ,c ,d1 fig4 #abf1 but instead of standing vertical1 as in fig4 #abc1 they are represented in a horizontal position1 and the board on which they are drawn is fastened to the cross-head1 ,l1 so that the former will move backward and forward simultaneously with the latter and the piston4 ,a small shaft1 ,f1 is attached to suitable supports1 j1 which are fastened to the guides4 ,this shaft has two arms1 ,g and ,e1 one vertical and the other horizontal and of the same length4 ,the upper end of the vertical one1 ,g1 is then attached to the valve-stem or rocker-arm by a short connecting-rod1 ,h1 or other suitable means1 so that the movement of the valve-stem will be imparted to the arm and shaft4 ,of course the end of the horizontal shaft then has exactly the same motion vertically that the valve-stem and valve have horizontally1 with the very trifling inaccuracy due to the fact that the movement of the one is in a straight line1 whereas the other is in the arc of a circle4 ,now if a pencil1 ,p1 is attached to the end of the horizontal arm1 ,e1 and is set so that its point indicates the exact position of the steam edge1 h1 of the valve1 as shown in fig4 #abc1 it is obvious that when the piston and board have moved four inches1 the pencil will have moved downward and have drawn the portion of the motion-curve from h to i2 and when the piston has moved eight inches the curve will be drawn to j1 and at #ab1 #af1 #bj and #bd inches of the stroke the curve will be drawn to k1 l1 m and n4 ,during the return stroke a corresponding curve1 n o h1 will1 of course1 be drawn4 ,with such an instrument curves can be drawn for any position of the link1 and they will show the exact movement of the valve during the whole stroke1 and will indicate all the defects resulting from bad proportions or construction1 lost motion in the parts1 or other causes of error or irregularity4 ,illustration3 ,fig4 #abf4--,scale in4 #a foot4 ,in using this instrument1 however1 it is impracticable to attach a board to the inside of the cross-head1 and it must therefore be fastened to the outside4 ,the horizontal arm ,e should be made of thin steel1 so as to form a spring4 ,the end has a small boss#ee with a hole in it of an inch in diameter4 ,this hole has a screw thread cut in it1 into which an ordinary hard drawing pencil is screwed4 ,the spring is so arranged that the pencil will not be in contact with the board unless it be pressed against it4 ,the locomotive is then placed on a smooth piece of track with steam on and run very slowly1 so that a person walking alongside can press the pencil against the surface of the board1 which should be covered with drawing paper4 ,by watching the cross-head when it reaches the end of the stroke1 the pencil can then be pressed against the paper and kept in contact through the whole stroke and instantly released when the motion-curve is completed4 ,the link can then be placed in another position1 and thus any number of curves can be drawn1 which will furnish the most accurate means of analyzing the motion of the valve4 #ee ,the term 8boss0 is used to imply an enlargement or increased thickness of any part4 ,in practice it is best not to draw the lines which represent the edges of the ports1 until after the curves are drawn and the paper removed from the board4 ,a centre line must1 however1 be drawn on the engine from which to lay off the ports4 ,this can be done by placing the valve in its middle position1 and then fastening the shaft ,f in that position with a nut which should be provided for that purpose on the end of the shaft4 ,after it is fastened in this position1 detach the connecting-rod ,h1 and with one stroke of the piston a centre line can be drawn with the pencil ,p4 ,from this centre line the edges of the ports can easily be laid off and drawn on the paper after it is taken off the engine4 ,,question #aic4 ,can the position of each edge of the valve1 with any given amount of travel1 be shown in its relation to the ports by one motion-curve1 or is it necessary to draw such curves for each edge of the valve1 as shown in fig4 #bh8 ,answer4 ,one motion-curve is sufficient to represent the position of any part of the valve during the entire stroke4 ,this will be apparent if it is remembered that each motion-curve is exactly like the others1 as shown in fig4 #bh1 the only difference being that the ports occupy different positions in relation to the curves4 ,it is1 therefore1 only necessary to draw lines to represent the relative positions of the ports to the other curves to show the entire motion of the valve by one curve4 ,to illustrate this it will be assumed that a motion-curve1 h i j k l m n o p1 and a centre line1 a b1 fig4 #abg1 have been drawn with the instrument described in the answer to the previous question4 ,the centre line a b1 which will be equal in length to the stroke of the piston1 should then be divided into inches1 and lines ff1 #bc #a1 #bb #b1 etc41 should be drawn through the points of division and at right angles to a b4 ,if1 now1 we want to show the movement of the front steam edge of the valve in relation to the corresponding steam port1 a line1 t1 should be drawn perpendicular to f f1 to represent that edge of the valve at the beginning of the stroke4 ,as it is impossible to determine accurately the position of this steam edge at the beginning of the stroke from the motion-curve1 which is then tangent#ef to the line f f1 we must lay it off from the centre line1 a b4 ,this can readily be done if we remember that if a valve has in4 lap when it is in the middle position1 as shown in fig4 #bg1 and in4 lead at the beginning of the stroke1 it must have moved in4 from the middle position at the beginning of the stroke as shown in fig4 #bh4 ,the line t must therefore be drawn in4 from a b to represent its proper position in relation to the motion-curve1 and as it has in4 lead1 the steam edge1 h h1 of the steam-port must be drawn at that distance from t4 ,another line1 m m1 can then be drawn to represent the width of the front steam-port1 c c4 ,from these lines the movement of the valve in relation to the front port1 c c1 and the admission of steam are shown as clearly as in fig4 #bh4 #ef ,a curve is said to be tangent to another carve or to a straight line when the two just touch1 but do not intersect or cross each other4 ,if now we want to represent the motion and relative position of the back steam edge of the valve in relation to its port1 it is only necessary to assume that the line t represents that edge1 and that the curve h i j k l m n o h represents its motion1 and to draw the back steam-port in its proper relation to it4 ,when the valve is in its middle position1 as shown in fig4 #bg1 the outside edge of the port h is in41 or a distance equal to the lap1 from the steam edge q of the valve4 ,as the center line a b1 fig4 #abg1 represents the middle position of the edge of the valve1 it is only necessary to draw a line1 n n1 in41 or the same distance from the centre line a b that the outer edge of the port d is from q in fig4 #bh1 to represent this edge of the port in fig4 #abg1 and another b b1 at a distance from the former equal to the width of the port1 to represent its inner edge4 ,a line1 q1 below the line #j #bd1 will represent the edge of the valve at the beginning of the forward stroke4 ,the curves in relation to the port d will then show the motion of the valve in relation to this port1 in the same way that the dotted curve d f does in fig4 #bh4 ,illustration3 ,fig4 #abg4 ,scale inch #a inch4 ,if it is desired to represent the motion of the exhaust edge h1 fig4 #bh1 of the valve1 it is only necessary to imagine that the line t1 fig4 #abg1 represents that edge1 and then draw in the port d in the same relation to it that it bears to the edge h1 in fig4 #bh4 ,this has been done in dotted lines1 c c and e e1 in fig4 #abg4 ,if the reader will cut a paper section of a valve like that shown in fig4 #bg and place the different edges1 h1 i1 h and q1 so that they will successively correspond with the line t in fig4 #abg1 the diagram will perhaps be more clear4 ,if1 for example1 the paper section be placed to the right of the line t1 so that the edge h will correspond with t1 then it will be seen that the port c occupies the same relation to it that it does in fig4 #bh4 ,if the valve be placed to the left1 so that the edge q corresponds with t1 then the port d will be in the same relation to it that it has in fig4 #bh4 ,if the edges i and h be made to correspond with t1 then the ports drawn in dotted lines in fig4 #abg will represent the ports c and d in fig4 #bh4 ,the position of the ports in relation to the centre line of the motion-curve can be determined1 if it is kept in mind that the centre line a b1 fig4 #abg1 represents the position of the different edges of the valve when the latter is in the middle of the valve-face as shown in fig4 #bg1 and that the ports must be on the same side1 and the same distance from the centre line that they are from the edge of the valve whose motion is represented4 ,thus if the movement of the steam edge h in relation to its port1 c1 was represented1 the edge of the latter must be drawn on the motion diagram the same distance from the centre line that it is from h when the valve is in its middle position as shown in fig4 #bg4 ,this distance is of course just equal to the lap of the valve4 ,if the motion of the exhaust edge h was represented in relation to the steam port d1 then the inside edge of the latter would be drawn the same distance from the centre line a b in the diagram that the inner edge of the port is from the edge h of the valve1 which is equal to the inside lap4 ,the exhaust port could also be drawn in the same way1 but it would be liable to confuse a diagram made to so small a scale as that which has been employed for the accompanying illustrations1 and it has therefore been omitted4 ,diagrams of this kind which are made full size will1 of course1 show the movement of the valve more distinctly than is possible in the space occupied by the illustrations herewith4 ,when they are made of full size1 the lines indicating the ports should be drawn of different colors1 so as to distinguish them from each other easily4 ,such diagrams will show the position of the valve in relation to the ports1 and indicate the distribution of the steam during the whole stroke4 ,it is only necessary to refer the curve to the proper line to determine the position of the valve in relation to either of the ports for either the admission or release of the steam4 ,if1 for example1 we want to observe how the admission of steam is governed by the valve1 by referring to fig4 #abg we see that at the beginning of the backward stroke the valve has inch lead2 that at #a inches of the stroke the port c is wide open1 as shown by the intersection of the motion-curve with the line m m2 that the valve has received its maximum backward travel at #i inches of the stroke1 and begins to close the port at #ae inches1 and completely closes it at #ba inches of the stroke4 ,by referring the motion-curve to the lines n n and b b1 we see that the valve as shown by the line q at n again has inch lead at the beginning of the forward stroke2 that the steam port is wide open at #a inches of the stroke2 begins to close at #af inches1 and is completely closed at #ba inches4 ,by referring the curve to the lines e e and c c we see that the front port begins to open to the exhaust before the piston has completed its forward stroke and when it has nearly an inch to move1 that it is wide open almost immediately after the piston begins its stroke1 does not begin to close until the piston has moved #ai inches of its stroke1 and is completely closed at #bc inches of the stroke4 ,by referring the curve to the lines d d and g g1 almost the same phenomena will be observed for the forward stroke4 ,in fact from such a diagram the whole motion of the valve can be studied and analyzed with the greatest accuracy2 and1 as has already been shown1 the motion imparted to a slide valve by a link is of so complicated a nature that it is almost or quite impossible to observe its exact nature without such diagrams4 ,,question #aid4 ,can a motion diagram be constructed to represent the motion of the valve with different amounts of travel8 ,answer4 ,yes2 it is only necessary to construct motion-curves for the same diagram for each distance traveled1 and they will show the movement of the valve for the given amount of travel represented by the curves4 ,this has been done in fig4 #abh1 which is a reduced copy of a series of motion-curves taken from a locomotive4 ,from this diagram the movement of a slide-valve worked by the link-motion can be seen from the highest to the lowest practicable point of cut-off4 ,for convenience of reference the curves have been numbered4 ,illustration3 ,fig4 #abh4 ,scale inch #a inch4 ,the smallest travel of the valve represented by curve ,no4 #a is a little less than #b in41 and the ports are then opened only about in41 and the steam is cut off at #h in4 on the backward and #f in4 on the forward stroke4 ,the exhaust is opened or the steam is released during the backward stroke at #ag in41 and during the forward stroke at #af4 ,when the valve works with its greatest travel1 as represented by curve #h1 it travels #e in41 and opens the steam port wide at #c in4 of the backward stroke and #b in4 of the forward stroke4 ,the steam is cut off at #bj and #bj in41 and its release takes place at #bc in4 of each stroke4 ,the following table gives the greatest width of opening1 the point of cut-off1 the point of release1 and the lead for each motion-curve on the diagram4 ,this table has been made up from the motion-curves drawn with the instrument described in answer to ,question #aia1 on a locomotive which had been running about eighteen months and whose valve-gear consequently was considerably worn1 as s indicated by the flatness of the motion-curves on each side at the point when the motion of the valve was reversed4 ,this flatness was caused by the lost motion in the valve-gear1 the pencil remaining for a time stationary when the motion was reversed and while the parts were moving from their bearings on one side to those on the other4 ,the curves and the table therefore show the operation not of a theoretically perfect valve-gear1 but are examples of actual practice1 with such imperfections as are incidental to ordinary locomotives4 ,it will be seen that the instrument shows not only what the valve-gear should1 but what it actually does do1 and delineates all its imperfections4 ,width of opening ,point of ,point of of steam-port4 cut-off4 release4 ,no4 ,travel--------------------------------- --------- of of ,backwd,forw'rd ,backwd,forw'rd,backwd ,forw'rd curve4valve4stroke4stroke4stroke4stroke4 stroke4stroke4,lead4 ---------------------------------------- ------------------- in4 in4 in4 in4 in4 in4 in4 in4 #a #b #h #f #ag #af #b #b #i #i #ah #ah #c #b #ab #aa #ai #ai #d #c #ad #ad #bjbj #e #c #af #af #baba #f #d #a #a #ah #ah #bb #bb #g #d #a #a #ai #ai #bbbb #h #e #a #a #bj #bj #bc #bc - ,,question #aie4 ,what are the chief dimensions of the valve-gear represented in fig4 #abh8 ,answer4 ,the throw of eccentrics was #e in41 the steam-ports were #a in41 and the exhaust-port #b in4 wide1 the valve had in4 outside and inside lap and in4 lead at full stroke4 ,,question #aif4 ,what relation is there between the distance which the ports are opened by the valve1 and its travel when worked by a link8 ,answer4 ,as explained in the answer to ,question #eb1 the width which the steam-ports are opened by the valve for the admission of steam diminishes with the travel of the valve4 ,this is shown very clearly by the motion-curves1 and also in the above table1 from both of which it will be seen that when the valve travels only #b in4 the steam-ports are opened only in4 for the back stroke and for the front4 ,with #b travel the opening is and in4 ,with #d in4 travel the port is opened #a and #a in4 and with #d in4 travel they would be opened wide4 ,with #d and #e in4 travel1 as will be seen from the motion diagram1 the ports are not only opened wide1 but the valve throws 8over0 them1 or travels beyond their inner edges4 ,,question #aig4 ,how is the point of cut-off affected by the link8 ,answer4 ,changing the travel of a valve with a link has a very similar effect to that produced by eccentrics of different throw--that is1 the period of admission is increased with the throw of the eccentric and that for expansion lessened4 ,this is shown clearly in both the motion diagram and the table4 ,with the first curve and a travel of #b in4 the steam is cut off at #h in4 for the backward stroke and #f in4 for the front1 and with #e in4 travel steam is admitted during #bj in4 of the backward and #bj in4 of the forward stroke4 ,,question #aih4 ,how is the point of release or exhaust of the steam affected by the link8 ,answer4 ,as the travel increases1 it is delayed until later in the stroke4 ,thus1 with #b in4 travel the steam is exhausted or released from the cylinder during the backward stroke when the piston has moved #ag in41 and on the return stroke at #af in41 whereas1 with #e in4 travel of the valve1 the release is delayed until #bc in4 of the stroke4 ,an examination of the diagram and table will show very clearly the relation of the point of release to the travel4 ,,question #aii4 ,how is the lead affected by the ordinary link motion8 ,answer4 ,it is increased as the travel is diminished1 as is shown in the table1 and also by the inclination of the curves at the top and bottom of the diagram4 ,illustration3 ,fig4 #abi4 ,fig4 #acj4 ,fig4 #aca4 ,scale in4 #a foot4 ,,question #bjj4 ,what is the cause of this change of the amount of lead8 ,answer4 ,this can be best explained by reference to fig4 #abi1 which represents a link with very short eccentric rods4 ,if now the centre from which the link was drawn was in the centre of the axle ,s1 and the eccentric straps embraced the axle instead of the eccentrics1 their ends c and d would each describe the same arc1 a b1 parallel with the centre line1 x y1 of the link1 and the latter could then obviously be raised and lowered without moving the rocker-pin at all4 ,but the eccentric straps being attached to the eccentrics1 as shown by the dotted lines1 when the rods are raised or lowered they describe arcs1 c e and g h1 from the centres s and t of the eccentrics1 and not from the centre of the axle4 ,when the link is raised then1 the end of the upper rod obviously moves in the arc c e1 and the top of the link is moved from the axle1 as shown in fig4 #acj1 a distance equal to the interval between the arc1 a b1 drawn from the centre of the axle1 and e f1 which the rod describes from the centre of its eccentric4 ,when the link is lowered from back to mid-gear1 a similar action takes place1 as the end1 d1 fig4 #acj1 of the lower rod describes an arc1 f g1 so that the whole link is thrown from the axle a distance equal to the space between the arcs described from the centre of the axle and the centres of the eccentrics4 ,when the position of the eccentrics is reversed1 as shown in fig4 #aca1 the link is moved towards the axle1 thus causing an increase of lead on the opposite side of the valve4 ,we have employed for our illustrations very short eccentric rods1 in order to make this action apparent by exaggerating it4 ,it is obvious from the engravings that the difference in the lead is increased as the eccentric rods are shortened1 and also as the distance between the points of connection of the rods with the link is increased4 ,it will also be plain that increasing the throw of the eccentrics1 that is1 increasing the distance of the centres s1 s1 of the eccentrics from the centre ,s of the axle will also increase the variation in the lead in full and mid-gear4 ,,question #bja4 ,what is meant by the distribution of steam in the cylinder8 ,answer4 ,it means the admission and exhaust of steam to and from the cylinder in relation to the stroke of the piston or the revolution of the crank4 ,,question #bjb4 ,what are the principal periods or elements of the distribution of steam by the slide-valve and link motion8 ,answer4 ,they are3 #a4 ,the pre-admission or lead1 that is1 the admission of steam into the cylinders in front of the piston before it has completed its stroke4 #b4 ,the admission of steam after the piston has commenced its stroke4 #c4 ,the expansion of steam in the cylinder4 #d4 ,the pre-release1 or exhaust of steam before the piston has completed its stroke4 #e4 ,the release1 or exhaust during the return stroke of the piston4 #f4 ,the compression of steam1 or closing the exhaust before the piston has completed its return stroke4 ,,question #bjc4 ,what is meant by the clearance of the piston8 ,answer4 ,it is the space between the piston and the cylinder-head when the former is at the end of the stroke4 ,if the piston touched the cylinder-head at the end of each stroke1 it would cause a concussion or 8thump0 which would injure these parts4 ,owing to the impossibility of constructing machinery with absolute accuracy1 it is therefore necessary to leave a space1 usually from to in4 wide1 between the piston and the cylinder-heads1 so as to be certain that they will not strike each other should there be any slight inaccuracies in the length of the piston-rods1 connecting-rods1 frames or other parts4 ,,question #bjd4 ,why is it desirable to open the steam-port and admit steam at the end of the cylinder towards which the piston is moving ,,before the latter has completed its stroke8 ,answer4 ,because it is essential1 in order to insure a good action of the steam1 that the maximum cylinder pressure should be attained at the very commencement of the stroke4 ,if the steam-port was not opened until after the piston had commenced its stroke1 some appreciable time would be consumed in filling the clearance space and the steam-way with steam4#eg ,it is also found1 especially if an engine is working at a high speed1 that a slide-valve worked by the ordinary link-motion will not open the steam-port rapidly enough to enable steam of the maximum boiler pressure to fill the space after the receding piston1 unless the valve begins to open the port before the piston reaches the end of its stroke4 #eg ,the steam-ways are the passages which lead from the steam-chest to the cylinder1 and are sometimes called steam-ports1 but the term steam-ways is used to distinguish the passages from their openings in the valve-seat1 which latter are more properly called steam-ports4 ,another advantage resulting from the pre-admission of steam consists in the smooth working of the engine at high speeds1 a circumstance which reduces greatly the wear and tear of the working gear4 ,as the piston approaches the end of its stroke1 the pre-admitted steam forms a kind of elastic cushion1 which is well calculated to absorb the momentum of the reciprocating parts at that instant4 ,the pressure due to the momentum of these parts will1 of course1 depend upon their weight and the speed of working1 increasing directly as the square of the speed4 ,it follows from this that the lead should increase with the speed1 and that it should be greatest at high speeds4 ,as has been shown before1 this condition is fully accomplished by the ordinary shifting-link motion4 ,,question #bje4 ,upon what does the admission of steam into the cylinder depend8 ,answer4 ,it depends in the first place upon the opening of the throttle-valve1 and the size of the pipes and passages through which it is conveyed from the boiler to the cylinder4 ,in the second place1 it depends upon the time and amount of opening of the steam-port by the valve4 ,,question #bjf4 ,what should be the pressure of the steam in the cylinder during admission8 ,answer4 ,in order that the steam may be used to most advantage1 it should be admitted and maintained in the cylinder at full boiler pressure during the whole period of admission4 ,if the opening of either the throttle-valve or the steam-ports is not sufficient to allow the steam to flow into the cylinder at full boiler pressure1 the steam is said to be wire-drawn1 and much of the advantage of using it expansively as has already been explained in answer to ,question #ei1 is then lost4 ,,question #bjg4 ,why is it difficult to admit and maintain steam at the full boiler pressure in the cylinder during admission8 ,answer4 ,because it is necessary to reduce the travel of the slide-valve in order to cut off the steam 8short10 or soon after the beginning of the stroke of the piston4 ,when the travel is reduced1 the valve opens the port only a small distance1 so that the area of the opening is not then sufficient to allow the steam to flow into the cylinder with sufficient rapidity to fill it at full boiler pressure1 especially if the engine is working at a high speed4 ,thus1 by referring to the table given on page #baf and to the motion curves in fig4 #abh1 it will be seen that when the steam is cut off at from to stroke1 the port is opened for the admission of steam only from to inch wide4 ,from the curves it will also be seen that the valve then acquires its maximum travel and the steam-port its greatest width of opening very soon after the piston begins its stroke2 after which the port is gradually closed1 so that before the steam is entirely cut off the opening is so much reduced in area that the steam cannot flow through it rapidly enough to maintain the steam at full boiler pressure in the cylinder when the engine is working at high speeds4 ,,question #bjh4 ,what means are used to overcome this difficulty and thus admit steam at full boiler pressure when the valve is cutting off short8 ,answer4 ,in the first place1 the steam-ports are made from ten to twelve times as long as they are wide1 so that a narrow opening will have a comparatively large area4 ,in the second place1 by giving the valve lead1 not only are the clearance space and the steam-way filled with steam when the piston begins its stroke1 but the port is then open a distance equal to the lead4 ,with the ordinary link motion1 as has already been shown1 this lead increases as the travel and period of admission diminish1 so that the smaller the total distance that the port is opened1 the greater is its opening at the beginning of the stroke4 ,as the steam is usually cut off short when locomotives run at high speeds1 it will be seen that the increased lead which is imparted to the valve by the shifting link is an advantage rather than a disadvantage4 ,but while it is often possible in this way to secure a pressure of steam in the cylinder at the beginning of the stroke equal or nearly so to that in the boiler1 yet it is almost impossible to maintain this pressure during the whole period of admission1 when the steam is cut off short and the engine working at a high speed4 ,to obviate this evil what is called the ,allen valve was designed1 which is represented in fig4 #acb4 ,this valve has a channel or supplementary port1 a a1 which passes over the exhaust cavity1 and has two openings1 b1 b1 in the valve-face4 ,when the valve begins to admit or 8take0 steam at c1 as shown in fig4 #acc1 it will be seen that it also uncovers the opening b at e and admits steam at b1 which passes through the channel b a a b and enters the steam-port c at b1 and in this way there is a double opening for the admission of steam4 ,the opening b of the supplementary port is closed as the valve advances1 but when this takes place the steam-port is uncovered far enough to admit all the steam that is required4 ,this form of valve is very efficient when the travel and point of cut-off are very short4 ,it then gives just twice as much opening as the ordinary valve for the admission of steam4 ,this improved valve has been much used in ,europe2 but1 although it is an ,american invention1 has not received the attention in this country which its merit deserves4 ,illustration3 ,fig4 #acb4 ,fig4 #acc4 ,scale in4 #a inch4 ,,question #bji4 ,what is meant by the pre-release of steam8 ,answer4 ,it is the release of the steam before the piston has completed its stroke4 ,if it is confined until the piston has reached the end of the cylinder1 there will not be time nor will it be possible1 with a slide valve and link-motion1 to secure a sufficiently large opening of the port to permit the steam to escape from the cylinder before the piston begins its return stroke4 ,if there were no pre-release1 there would therefore be more or less back pressure on the piston4 ,,question #baj4 ,upon what does the amount of pre-release depend8 ,answer4 ,first1 as has already been explained in answer to ,question #ea1 on the amount of inside lap2 and second1 on the outside lap of the valve and lead of the eccentrics2 and third1 on the travel of the valve4 ,the less the inside lap1 the greater the outside lap and consequent lead of the eccentrics2 and the shorter the travel of the valve1 the earlier will be the release4 ,the proper amount of this pre-release depends upon the velocity of the piston and the quantity of steam to be discharged or the degree of expansion4 ,from the motion-curves in fig4 #abh it will be seen that it is a marked feature of the shifting-link motion that the pre-release occurs earlier in the stroke as the link approaches mid-gear1 or as the travel of the valve diminishes4 ,as the link is usually worked near that position when the engine is run at a high speed1 it will be seen that in this respect again the link-motion is well adapted for working the slide-valves of locomotives4 ,,question #baa4 ,what governs the period of release8 ,answer4 ,the release like pre-release is dependent upon the amount of inside lap1 the outside lap and consequent lead of the eccentrics1 and the travel of the valve4 ,the addition of inside lap has the effect of closing the port earlier than it would be closed without1 and thus shortening the period of release and also of reducing the area of the opening of the port4 ,this will be apparent by referring to fig4 #abh1 in which the valve had in4 lead4 ,the dotted lines which represent the edges of the ports in relation to the exhaust edges of the valve are therefore drawn in4 from the centre line a b4 ,if1 however1 there had been no inside lap1 then the edges of the ports would have conformed to the line a b4 ,it will be observed that the first curve crosses the dotted line g g at #ae in4 of the forward stroke1 which is the point at which the port is closed to the exhaust1 or where the period of release ends and compression begins4 ,if there had been no lap and the line g g had therefore occupied the same position as a b1 then the motion-curve would not have crossed it until the piston had reached #af in4 of its stroke1 thus showing that the period of release had been lengthened and compression delayed4 ,as the width of the opening of the port is represented by the distance of the motion-curve from the right hand side of the line g g1 which represents the edge of the port1 it is obvious that if there had been no lap1 so that the position of the line representing the edge of the port had occupied the position of a b1 then the space between it and the motion-curve would have been greater1 thus showing that the port would have been opened wider if there had been no inside lap4 ,the width of the opening of the port to the exhaust is in fact always diminished by an amount equal to the inside lap4 ,with the same travel1 increase of outside lap and lead shortens the period of release1 but has no effect on the width of the opening of the port to the exhaust4 ,increase of travel1 with the same outside lap1 lengthens the period of release and also increases the width of the opening of the port to the exhaust4 ,,question #bab4 ,what governs the period of compression8 ,answer4 ,as compression begins when release ends1 or when the port is closed to the exhaust1 it is controlled by exactly the same causes1 and as the two events occur simultaneously1 of course whatever shortens the period of release lengthens that of compression4 ,,question #bac4 ,what effect do the clearance spaces and steam-ways have upon the compression of the confined steam8 ,answer4 ,by referring to the motion-curves in fig4 #abh1 it will be seen that the steam-port is closed by the exhaust edge of the valve1 or compression begins some time before the piston reaches the end of the stroke4 ,the result is that the remaining portion of the cylinder1 through which the piston must move after the port is closed to the exhaust1 is filled with steam of atmospheric pressure1 or possibly a little above that pressure4 ,as this is confined in the cylinder1 it is compressed by the advance of the piston4 ,if there was no room between it and the cylinder at the end of the stroke1 then either the cylinder would be burst or the valve would lift so as to allow the compressed steam to flow back into the steam-chest4 ,the clearance and the steam-passages1 however1 afford considerable room1 into which the confined steam can be compressed without danger of bursting the cylinder1 or of raising the slide-valve when there is steam in the steam-chest4 ,as the clearance spaces and steam-ways must be filled with high-pressure steam at the beginning of each stroke1 it must be obtained either by taking a supply of 8live0#eh steam from the boiler1 or by compressing into the clearance spaces the low-pressure steam that still remained in the cylinder when the port was closed to the exhaust4 ,by the latter process1 a certain quantity of steam is saved at the expense of increased back pressure4 ,it should be borne in mind also that the total heat of the compressed steam increases with its pressure1 and as this latter approaches that in the boiler1 the temperature of the former must have been raised from that due to about atmospheric pressure to nearer the temperature of that in the boiler4 ,these changes of temperature which the steam undergoes will affect the surface of the metal with which the steam is in contact during the period of compression2 it follows from this1 that the ends of the cylinder principally comprising the clearance spaces must acquire a higher temperature than those parts where expansion only takes place4 ,this is an important consideration1 since the fresh steam from the boiler comes first in contact with these spaces1 and by touching surfaces which have thus previously been heated1 as it were1 by the high temperature of the compressed steam1 less heat will be abstracted from the fresh steam1 and therefore a less amount of water will be deposited in the cylinder4#ei #eh ,the term 8live0 steam means steam taken direct from the boiler and which has not been used in the cylinder or to do any work4 #ei ,bauschinger's ,indicator ,experiments on ,locomotives1 published in ,vol4 ,,iii4 of the ,,railroad ,,gazette4 ,it will thus be seen that the effect of compression is to fill the clearance spaces and steam-ways with compressed steam before pre-admission begins4 ,as already stated1 this is done at the expense of back pressure in the cylinder4 ,it must be remembered that all the energy1 excepting that part which is wasted by loss of heat1 friction1 etc41 which is consumed in compressing the confined steam1 is again given out to the piston by expansion4 ,the confined steam also acts as an elastic cushion to receive the piston1 just as the steam which is admitted before the end of the stroke would if there were no compression4 ,compression1 therefore1 has the effect of saving the quantity of live steam which it would otherwise be necessary to admit before the end of the stroke to fill the clearance spaces and steam-ways and also to 8cushion0 the piston4 ,as already stated1 the momentum of the piston and other parts depends upon their weight and the speed at which they are working1 increasing directly as the square of the speed1 from which it follows that the compression should increase rapidly with the speed1 and should be the greatest at high speeds4 ,as the ports are prematurely closed to the exhaust with the shifting-link motion1 and as the lead increases rapidly as the link approaches mid-gear1 and the amount of compression is at the same time correspondingly augmented1 it will be seen that the shifting-link motion fulfills these conditions very perfectly4 ,the pressure to which the confined steam will rise depends of course upon the amount of the period of compression1 and also on the size of the clearance spaces4 ,as it is possible to have such an amount of compression that it will exceed the boiler pressure1 and thus raise the valve from its seat and be forced back into the steam-chest1 some care must be exercised to proportion the one to the other1 so that the degree of the confined steam may not be excessive4 ,,question #bad4 ,how can the effect of the distribution of the steam upon its action in the cylinder be determined by experiment8 ,answer4 ,as already explained in answer to ,question #ee1 this can be done by an instrument called a steam indicator4 ,illustration3 ,fig4 #acd4 ,illustration3 ,fig4 #ace4 ,scale #c in4 #a foot4 ,,question #bae4 ,what is the construction of this instrument8 ,answer4 ,the indicator now ordinarily used is the ,richards indicator1 the outside of which is represented in fig4 #acd and a section in fig4 #ace4 ,it consists of a cylinder1 ,b1 into which a piston1 ,c1 is accurately fitted1 but so that it will move freely in the cylinder4 ,the piston rod is surrounded with a spiral spring1 ,d1 the lower end of which is attached to the top of the piston1 and the upper end to the cylinder cover4 ,when steam is introduced below the piston it pushes it up in the cylinder and the spring is compressed4 ,if there should be a vacuum below the piston1 the air above it will press the piston downward and extend the spring4 ,this latter occurs only when the indicator is used on condensing engines4 ,of course the distance which the piston is forced up by the steam pressure below it depends upon the amount of pressure and also on the tension of the spring2 and therefore by attaching a pencil to the piston-rod so that it can mark on a moving card in front of it1 a diagram will be drawn which would indicate the steam pressure1 as was explained in answer to ,question #ee4 ,but there are some practical difficulties in the way of doing this4 ,it is found that if the pencil is attached directly to the piston-rod of the indicator1 the distance through which they must move1 in order to make the scale of the diagram sufficiently large to be clear1 is so great that the momentum of the parts carries them further than the pressure of the steam alone would move them4 ,the distance through which the pistons or instruments move1 moreover1 makes it impossible that the changes of pressure should be indicated simultaneously with the position of the piston2 the latter must travel while the action is taking place1 and thus the diagram shows changes of pressure later or more gradually than they occur4#fj ,to overcome these and other difficulties1 the piston-rod of the indicator which we have illustrated is attached at h to the short arm of a lever1 ,f ,g1 and to the end of the long arm a piece1 ,f ,i1 is attached1 which carries a pencil1 ,j4 ,by this means the piston has only one-fourth of the motion that it imparts to the pencil1 so that the momentum of the moving parts is comparatively slight4 ,if the pencil was attached directly to the end of the lever1 it is obvious that it would move in the arc of a circle1 and that this would be a source of error in the diagram4 ,to avoid this the pencil is attached to what is called a 8parallel motion40 ,this consists of a coupling-rod1 ,f ,i1 which connects the ends of two levers1 ,f ,g and ,i ,h4 ,the centre of the rod ,f ,i1 to which the pencil is attached1 will with this arrangement move in a straight line4 ,the levers and all the parts are of course all made as light as possible1 so that their weight will have little effect on the motion of the indicator piston4 #fj ,richards' ,steam ,indicator1 by ,charles ,t4 ,porter4 ,the paper or card on which the diagram is drawn is wrapped around a brass cylinder1 ,a ,a4 ,this cylinder is made to revolve part of the way around by a strong twine1 a b1 which is wrapped around a pulley1 b1 at the bottom of the cylinder4 ,the twine is attached to a lever1 similar to that shown in fig4 #cj1 which receives a reciprocating motion from the piston of the engine4 ,the twine can of course move the cylinder only in one direction1 and therefore a coiled spring similar to a clock spring is placed inside of the cylinder to draw it back when the twine is relaxed4 ,in this way the paper cylinder or drum receives a part of a revolution at each stroke of the piston1 and moves simultaneously with it4 ,this drum is used instead of a flat card1 on account of the practical difficulties of employing the latter4 ,the motion of the paper on this drum will1 however1 be exactly the same in relation to the pencil as the motion of a flat card would be4 ,illustration3 ,fig4 #acf;a4 ,the method of attaching an indicator to a locomotive is represented in fig4 #acf;a4 ,it will be seen from this that it is placed over the center of the steam chest and connected to each end of the cylinder with -inch pipes4 ,a globe valve was in the case represented placed on each side of the indicator1 so that it could be put into communication with either end of the cylinder1 or could be completely shut off from both4 ,a better plan1 however1 is to have a three-way cock at the point where the horizontal pipe connects with the vertical one leading to the indicator1 as the passages in a three-way cock are more direct than those in globe valves4 ,the arrangement of the levers for giving motion to the indicator drum1 and of the seat1 which is very requisite for the experimenter1 will be readily understood from the engraving without further explanation4 ,it is thought by some engineers that the indicator should be applied as near to each end of the cylinder as possible4 ,it is believed1 however1 that if the pipes1 cocks1 and their connections are made large enough so as not to impede the motion of the steam1 no appreciable error will arise from the method illustrated in fig4 #acf;a4 ,,question #baf4 ,what should be the form of an indicator diagram1 if the steam is distributed by a link motion so as to produce the best practicable action in the cylinders8 ,answer4 ,it should approximate to that shown in fig4 #acf;b4 ,in this diagram the vertical lines represent inches of the stroke1 and the scale on the left the steam pressure in pounds per square inch4 ,the atmospheric and vacuum lines are also indicated1 as already explained in answer to ,question #ee4 ,the points at which the different periods of the distribution begin are indicated by the letters a1 b1 c1 d1 e and f4 ,these are in the order in which they occur3 a1 pre-admission2 b1 admission2 c1 expansion2 d1 pre-release2 e1 release2 and f1 compression4 ,the lines forming the outline of the diagram will be designated for convenience of description as follows3 ,the line from a to b1 the admission line4 ,the line from b to c1 the steam line4 ,the line from c to d1 the line or curve of expansion4 ,the line from d to e1 the exhaust line4 ,the line from e to f1 the line of back pressure4 ,the line from f to a1 the line or curve of compression4 ,illustration3 ,fig4 #acf;b4 ,the diagram represents a distribution of steam produced by a valve having in4 outside and inside lap1 and operated by the link motion represented in fig4 #ajc4 ,the eccentrics have #e in4 throw1 and the steam-ports are #a and the exhaust #b in4 wide4 ,the valve as shown by the diagram is cutting off at #h in41 or one-third of the stroke4 ,pre-admission begins when the piston still has in4 to move before reaching the end of its stroke4 ,admission of course begins with the stroke1 expansion at #h in41 pre-release at #ah in41 release at the end of the stroke1 and compression at #ag in4 of the return stroke4 ,the valve is supposed to be set without any lead1 or 8line and line10#fa as it is called at full stroke4 ,when the steam is cut off at #h in4 of the stroke1 the valve has #b in4 travel and in4 lead4 ,the steam pressure in the boiler is supposed to be #ajj pounds above the atmosphere4 ,of course1 when the valve cuts off at different points of the stroke1 the periods of distribution will be somewhat changed2 but from the above diagram the principal features of a good distribution can be explained4 #fa ,that is1 the steam edges of the valve correspond with the steam edges of the port at the beginning of the stroke4 ,these are3 ,first1 that the steam pressure should rise rapidly during the period of pre-admission1 so that there will be full boiler pressure in the cylinder at the beginning of the stroke4 ,when this occurs1 the pre-admission line will rise from a to b1 to such a point at b which will indicate full boiler pressure in the cylinder4 ,the same pressure should then be maintained in the cylinder during the whole period of admission1 and the admission line from b to c should therefore be a straight horizontal line1 as shown in fig4 #acf;b4 ,when expansion begins1 the pressure will fall1 as was explained in answer to ,question #ee4 ,the expansion line should approximate a hyperbolic curve1 but if there is much loss of heat by radiation or other causes1 the diagram will fall considerably below the theoretical curve4 ,with cylinders well protected and with dry steam the expansion line will fall slightly below a hyperbolic curve at the beginning of the period of expansion1 and rise above it during the latter part of the same period4 ,the reason of this is that the cylinder is heated by the admission of live steam of comparatively high pressure and temperature1 so that1 when the pressure becomes reduced by expansion1 a part of the water which is condensed in the cylinder will be re-evaporated by the heat in the latter4 ,from the point of the pre-release1 d1 to the end of the stroke1 e1 the exhaust line should fall rapidly1 so that there will be no pressure behind the piston during its return stroke4 ,to explain the theoretical form of the exhaust line would lead us into a very abstruse discussion1 which would be out of place here4 ,it will be sufficient for our purpose to call attention to the fact that the pre-release should allow all the steam in the cylinder to escape before the piston reaches the end of the stroke1 so that the back pressure during the return stroke may be as low as possible4 ,it is1 however1 only at comparatively slow speeds that the steam in locomotive cylinders escapes during the period of pre-release1 so that the back pressure is reduced to that of the atmosphere4 ,it is necessary in locomotives1 as has already been explained1 to contract the area of the blast orifices or exhaust nozzles1 in order to stimulate the draft through the fire1 so that the steam cannot escape with sufficient rapidity to reduce the back pressure to that of the atmosphere if the engine is running fast4 ,of course every pound of back pressure on the piston is so much loss of energy1 and a reduction of the amount of work done by the engine2 but it is a sacrifice which must be made in order to be able to generate the requisite quantity of steam4 ,in studying the distribution of steam1 however1 every effort should be made to reduce the back pressure as much as is practicable1 and yet maintain a sufficient supply of steam1 and therefore the line of back pressure should conform as closely as possible to the atmospheric line4 ,the compression line should be a hyperbolic curve1 beginning with the period of compression4 ,in calculating both the compression and expansion1 allowance must be made for the clearance space and steam-way4 ,in a cylinder like that illustrated in fig4 #ib1 their contents would be about equal to that of two inches of the cylinder4 ,therefore1 when steam is cut off at #h in4 of the stroke1 instead of having a quantity of steam which will fill a cylinder #af in4 diameter and #h in4 long1 we have as much as would fill a cylinder of that diameter and #aj in4 long4 ,the same thing is true of the compression4 ,this must occur in the above example when the piston has #f in4 more to move before completing its stroke4 ,there is therefore a quantity of steam in front of it sufficient to fill a cylinder #h in4 in diameter4 ,this steam is of course compressed by the advance of the piston1 and if its pressure when compression begins is the same as that of the atmosphere1 then it will be #j4i lbs4 above it when the piston has only #f in4 to move and #c4b1 #f4b1 #aj4e1 #af4i1 and #bg4e lbs4 effective pressure when the piston has #e1 #d1 #c1 #b and #a inches to move respectively1 and when pre-admission begins1 the pressure will have risen to #dh4g lbs4 ,if the back pressure is above that of the atmosphere1 of course the compression will be correspondingly increased4 ,it will also be seen that1 without any or with very little clearance space1 the compression would at the end of each stroke rise above the boiler pressure4 ,it being a peculiarity of the ordinary shifting-link motion that as the period of admission is reduced that of compression is lengthened1 the latter becomes very excessive when the steam is cut off at less than one-third or one-fourth of the stroke4 ,,question #bag4 ,in what respect would a diagram made by an indicator differ from the theoretical form represented in fig4 #acf;b8 ,answer4 ,it would be drawn with less exactness2 that is1 the corners instead of being sharply defined1 as in fig4 #acf;b1 would be more or less rounded1 as in fig4 #acg1 and the curves and straight lines would vary somewhat from the exact mathematical form indicated in fig4 #acf;b4 ,the higher the speed at which the engine is working when the diagrams are taken1 the greater will be the variation from the theoretical form4 ,illustration3 ,fig4 #acg4 ,,question #bah4 ,if the amount of pre-admission is insufficient1 how will it be shown in the indicator diagram8 ,answer4 ,the effect of too little pre-admission is to lower the pressure of the steam at the beginning of the stroke1 and at high speeds there will not be time enough nor sufficient opening of the steam-port to supply the deficiency after the stroke has commenced4 ,the corner of the diagram at b will then be very much rounded1 as shown in fig4 #ach4 ,this is apt to be the case when steam is admitted during a considerable part of the stroke1 as a shifting-link motion then gives less lead than when it is worked nearer mid-gear4 ,if the steam is cut off short1 then the pressure in the cylinder during admission is very much below boiler pressure1 and is apt to fall rapidly after the commencement of the stroke1 as shown in fig4 #ach4 ,illustration3 ,fig4 #ach4 ,,question #bai4 ,if the opening of the steam-ports during admission is too small1 what will be the form of the diagram8 ,answer4 ,the effect will be very much the same as that produced by too little pre-admission or lead2 that is1 the pressure in the cylinder will be much lower than in the boiler and will fall rapidly during the periods of admission1 as shown in fig4 #ach4 ,,question #bbj4 ,what defects will be indicated by the expansion curve of indicator diagrams8 ,answer4 ,if the cylinders are not well protected1 and there is much loss of heat from radiation1 there will be a rapid fall of pressure during the period of expansion1 which will be shown by the expansion curve falling below the theoretical curve shown in fig4 #acf;b4 ,if1 on the contrary1 the indicator curve is much above the theoretical curve1 it may be caused by a leak in the valve4 ,as steam is quite as likely to leak from the steam-port into the exhaust as from the steam-chest into the steam-port1 a valve which is not tight may produce just the contrary effect upon the indicator diagram4 ,as it is usually quite easy to detect a leak in the valve by other means1 the use of the indicator for this purpose is unnecessary4 ,attention is called to it1 however1 to show the impossibility of getting results of any value with the indicator if the valves are not steam-tight4 ,,question #bba4 ,what should be observed regarding the exhaust line of the indicator diagram8 ,answer4 ,the most important point to be observed is1 whether the pressure at the end of the stroke is reduced as low as possible1 as at high speeds it is usually much more difficult to exhaust the steam from than to admit it into the cylinder4 ,as already stated1 the blast in the chimney makes it almost impossible to exhaust the steam to atmospheric pressure when the locomotive is running fast4 ,if the steam is released too late in the stroke1 as already explained1 there will not be time enough nor sufficient opening of the port to allow the confined steam to escape from the cylinder before the end of the stroke1 and this will be indicated on the diagram by the space between the line of back pressure and the atmospheric line during the commencement of the return stroke1 as shown in fig4 #ach4 ,,question #bbb4 ,what should be observed regarding the line of back pressure8 ,answer4 ,the most important point is1 that it should approximate as closely as possible to the atmospheric line1 as all the back pressure not only diminishes the efficiency of the engine1 but is a total loss of energy4 ,too much inside lap will increase the amount of back pressure1 but generally it is more influenced by the area of the blast orifices than by any other cause4 ,every effort should be made1 therefore1 to have them as large as possible and yet have the boiler make as much steam as is needed4 ,when only one blast orifice is used for both cylinders1 it often happens that when the steam is exhausted from the one cylinder it 8blows0 over into the other1 and thus produces an additional amount of back pressure4 ,this is shown by a rise or 8hump0 in the line of back pressure1 as indicated in fig4 #ach4 ,,question #bbc4 ,can the amount of compression which is needed be determined by calculation8 ,answer4 ,yes2 but it involves more abstruse principles of mathematics than it is thought best to introduce here4 ,some of the reasons can1 however1 be given1 which will make the subject clearer1 and enable the reader1 if he has sufficient knowledge of mathematics1 to investigate the subject still further4 ,illustration3 ,fig4 #adj4 ,in the first place it is a well-known fact that the motion of a piston in the cylinder of a steam engine is not a uniform one1 but increases in speed from the beginning of the stroke to the middle1 and diminishes in speed from the middle to the opposite end4 ,the cause of this is that the crank revolves at a uniform speed during the entire revolution1 but the piston moves much less at the beginning of the stroke1 with a given amount of revolution of the crank1 than it does at the middle4 ,this is shown in fig4 #adj1 in which ,a is a cylinder and ,b the piston and a b c d the path of the crank4 ,now while the crank moves from a to #a1 or of a revolution1 the piston has moved #a in41 or a distance equal to that from a to #a or to the base of a perpendicular drawn from #a to the centre line a c4 ,while the crank moves from #a to #b1 or through the second twelfth of a revolution1 the piston has moved from #a to #b1 or #d in41 or #b in4 further than during the first twelfth of the crank's revolution4 ,during the third twelfth of the revolution the piston moves from #b to #c1 or #f in41 thus showing that it continues to increase in the distance moved during each period of the revolution of the crank until the latter has made a quarter revolution4 ,the speed of the piston then begins to diminish until it reaches the end of the stroke4 ,it is slightly affected by the angularity of the connecting-rod1 as already explained1 but for the present this is disregarded4 ,it is obvious now that if the momentum1 or actual energy stored up in the piston and other reciprocating parts after they have passed the middle of the stroke1 added to the pressure behind the piston1 is greater than the resistance offered by the crank1 the motion of the latter will then be accelerated and thus conveyed to the moving engine and train4 ,if1 however1 there is any momentum in the piston when it reaches the end of the stroke1 evidently it can exert no power to cause the crank to revolve1 but must be expended by producing a pressure on the crank-pin and thus on the axle-boxes4 ,not only will such a pressure not cause the crank to revolve1 but it will be more difficult to turn the crank with such a pressure against it than it would be without4 ,the momentum of the piston and other reciprocating parts at the dead point therefore creates a resistance to the movement of the crank instead of helping to turn it4 ,it will also be observed that after the crank has moved slightly from the dead point1 any pressure on the piston will exert very little force which will tend to turn the crank4 ,in fact the nearer the piston is to the end of the stroke the greater is the proportion which the friction of the crank-pin and axle bears to the useful effect of the strain in causing the crank to turn4 ,calculation shows that for about three degrees on either side of the dead points the effect of pressure on the crank-pin is actually to retard the engine4 ,if now the piston reaches the end of the stroke with a certain amount of unexpended momentum stored up in it1 if this energy is expended by producing pressure on the crank1 then it will not only be a waste of energy but a double waste by retarding the motion of the crank4 ,if1 however1 this energy can be absorbed by compressing steam which will fill the clearance spaces1 it will not only prevent the retarding effect referred to1 but the energy in the piston and other parts will be converted into steam pressure1 which will be given out in useful work during the next stroke4 ,it would1 of course1 be impossible to arrest the motion of the piston instantly1 and therefore its momentum is gradually absorbed from the time compression begins until it reaches the end of the stroke4 ,as the energy of a moving body is equal to its weight multiplied by the square of its speed1 it is obvious that to overcome this a different amount of compression would be required for each speed1 and also that it must be adjusted to the weight of the moving parts4 ,such exact adaptation is not practicable on locomotives1 nor does the link motion enable us to alter the amount of compression with so much exactness3 but the explanation shows the value of increasing the amount of compression with the speed1 which fortunately the peculiarities of the shifting-link motion enable us to do without difficulty4 ,illustration3 ,fig4 #aci4 ,,question #bbd4 ,what cause produces the form of diagram represented by ,fig4 #aci8 ,answer4 ,it is produced by excessive compression1 which causes the pressure in the cylinder to rise above boiler pressure before pre-admission begins4 ,as soon as the port is opened1 part of the steam in the cylinder flows back into the steam-chest1 and thus the pressure is reduced1 as shown by the diagram4 ,,question #bbe4 ,how can we determine whether the steam is distributed in the cylinders to the best advantage1 and how can we discover the fault1 if there is one1 in the link motion8 ,answer4 ,the indicator will show the action of the steam in the cylinder1 and motion-curves drawn with the instrument described in answer to ,question #aib will show the exact movement of the valve4 ,by comparing the indicator diagram with the motion-curves1 the one will show the defects in the other4#fb #fb ,see description of ,richards' ,improved ,steam ,engine ,indicator1 with directions for its use1 by ,charles ,t4 ,porter1 ,london4 ,,question #bbf4 ,to what extent can the movement of the valve be modified by alterations in the proportions of the link motion8 ,answer4 ,the motion of the valve is susceptible of an almost infinite number of changes1 by different variations and combinations of proportions of the working parts of the link motion4 ,these changes are1 however1 limited by the general laws which govern the motion of eccentrics1 and therefore cannot influence the motion of the valve beyond certain limits4 ,hardly any variation can be made either in the proportions or arrangement of the working parts which will not have some influence upon the movement of the valve4 ,aside from the proportions of the valve itself1 which have already been discussed1 the throw of the eccentrics1 the length of the rods and of the link1 the point of connection of the rods with the link1 the point of suspension1 the position of the lifting shaft1 the length of the arms1 the length and position of the rocker arms will each of them effect the distribution of steam4 ,the number of combinations of all these different proportions is of course almost infinite1 and therefore any full discussion of them will be impossible here4 ,,question #bbg4 ,what are the most important points which require attention in designing a link motion8 ,answer4 ,it should be proportioned so that-- ,first1 the lead and the period of admission should be the same for each end of the cylinder1 for each point of cut-off1 and1 if possible1 in back as well as forward gear4 ,second1 the width of opening for both admission and exhaust should be as large as possible when steam is cut off short4 ,third1 the exhaust or pre-release should occur early enough and be maintained long enough to reduce back-pressure as low as possible4 ,,question #bbh4 ,how can the lead and period of admission be equalized8 ,answer4 ,it is impossible to make the periods of admission absolutely alike for every point of cut-off in both fore and back gear4 ,it is therefore customary to disregard the back gear1 as engines are worked but little with the link in that position4 ,even for forward gear the periods of admission cannot be made exactly alike for each end of the cylinder and for each point of cut-off1 and therefore it is usual to make the periods of admission alike for half-gear forward1 in which position the link is worked most4 ,the periods of admission for the front and back ends of the cylinder can be changed most in relation to each other by altering the position of the point of suspension on the link4 ,this can be done either by moving this point up or down1 or horizontally4 ,usually links are suspended from a point halfway between the points of connection of the eccentric-rods and from to in4 back of the centre line of the slot in the link4 ,a somewhat better distribution can be secured by suspending it about #c in4 above the centre1 but the suspending link must then be made so short that it is subjected to very great strains by the motion of the link1 and this evil is usually considered much greater than the advantage which is gained thereby in the more equal distribution4 ,the point at which the upper end of the suspension link is hung also influences the relative amount of admission front and back4 ,this point1 of course1 varies as the end of the lifting arm is raised or lowered4 ,in designing valve gear it is usually tested by a full-sized model1 which will show the exact motion of all the parts4 ,the best position for the lifting shaft and the length of its arm can be determined perhaps most satisfactorily by placing the link in full gear forward1 then moving the point of suspension of the upper end of the link-hanger horizontally so that the front and back admission will be alike1 and then marking this position4 ,the same process should then be repeated for half gear and for the shortest point of cut-off4 ,if the position of the lifting shaft and the length of its arm are then so arranged that the end of the latter will move through the three points which have been thus determined1 the admission will be very nearly equal for each end of the cylinder4 ,usually1 however1 it is impossible to arrange the shaft and arm so that they will conform exactly to these conditions1 and therefore an approximation is made which will come as near as possible to what is required4 ,it may be stated1 however1 that the lifting shaft should be kept as low as possible1 so as not to interfere with the eccentric-rods4 ,in some cases the shaft has been suspended from the boiler1 so that the outside eccentric-rod would work past or over the end of the lifting shaft1 thus allowing the latter to be located lower than would otherwise be possible4 ,,question #bbi4 ,which parts of the link-motion have the greatest influence on the distribution of steam8 ,answer4 ,the lap of the valve and the throw of the eccentrics4 ,the effect of any change of these upon the distribution is very similar to that produced if a single eccentric is used1 which was explained in the answers to ,questions #di1 #ej and #eb4 ,illustration3 ,fig4 #ada4 ,,question #bcj4 ,what is the effect upon the admission of increasing the throw of the eccentrics with the same lap8 ,answer4 ,as already explained1 the effect is to increase the period of admission1 or in other words to cut off later in the stroke1 and also to increase the width of the opening of the steam-port or the distance which the valve throws over the port4 ,this has an important influence upon the admission1 when the link-motion is used4 ,,question #bca4 ,what is meant by the angular advance of the eccentrics8 ,answer4 ,it is the angle which a line1 e f1 fig4 #ada1 drawn through the centre of the axle and the centre of the eccentric makes with a vertical line a b1 when the crank is on one of the dead-points or centres4 ,thus in fig4 #ada the crank ,a is represented on the front centre4 ,in order to give the valve the necessary lead the eccentric must be moved ahead of the vertical line a b4 ,the angle c which the line e f 7drawn through the centre of g of the eccentric and f of the axle7 makes with the vertical line is called the angular advance4 ,,question #bcb4 ,what is meant by linear advance8 ,answer4 ,by linear advance is meant the distance which the valve has moved from its middle position at the beginning of the stroke of the piston4 ,this1 when the two rocker arms are the same length1 is the same as the distance of the centre of the eccentric g from the vertical line a b1 fig4 #ada4 ,,question #bcc4 ,why does the cut-off occur earlier with an eccentric having a short throw than with one which gives more travel to the valve8 ,answer4 ,because it is necessary to give the eccentric with the short throw more angular advance in order to give the valve the required lead4 ,this is illustrated in fig4 #adb1 in which a section of a valve1 ,v1 and ports c1 g1 and d1 are represented4 ,in order to simplify the diagram as much as possible the rocker is left out and the valve is supposed to be moved by the rod ,r directly from the centre a of the eccentric4#fc ,the effect of the angularity of the connecting rod and eccentric rod is also neglected4 ,the circle a b e f represents the path of the centre of an eccentric having #e in4 throw1 and h i j the path of one having #c in4 throw4 ,in order to give the valve the required lead1 which is supposed to be just line-and-line at the beginning of the stroke1 the linear advance of the valve must be equal to the lap1 or in4 ,if therefore we draw a line1 p a1 parallel to the vertical centre line1 e k1 and in4 from it1 the intersection of p a at a and h with the paths of the eccentric will be the centres of the eccentrics4 ,if through these centres and the centre of the circle1 lines1 o a and o p1 be drawn1 the angles which they make with the vertical e k will be the angular advance4 ,it will be seen from these lines that in order to give the valve the required lead it is necessary to give the eccentric with the small travel more angular advance than is necessary for the one with the larger throw4 ,it is obvious1 too1 that when the centre of the larger eccentric has reached the point b the valve will have received its greatest travel1 and that when it reaches p the steam-port c will again be closed or the steam cut off4 ,if the small eccentric is employed1 the valve will then have its maximum travel when the centre h reaches s1 and the port will be closed when it reaches i4 ,by drawing lines1 o p and o n1 through i and p1 it will be seen that from the beginning of the stroke until the steam is cut off1 if the large eccentric is employed1 it1 and consequently the shaft and crank1 must move over an angle measured by the arc q t p4 ,if the small eccentric is used1 it and the crank must move through an angle measured by the arc u t n4 ,in other words1 the crank must turn a considerably greater distance before steam is cut off with an eccentric having a large than with one having a small throw4 #fc ,it will be seen that this causes the position of the centre of the eccentric to be reversed4 ,illustration3 ,fig4 #adb4 ,fig4 #adc4 ,scale in4 #a inch4 ,it is also quite obvious from fig4 #adb why the port is opened a shorter distance with a small than with a large eccentric4 ,the distances o s and o b are equal to half the throws of the eccentrics1 or #a and #b in4 ,the linear advance o r is in both cases in41 and therefore after the port begins to open the valve will be moved by the small eccentric a distance which is equal to #a - in41 and by the large one #b - #a in4 ,illustration3 ,fig4 #add4 ,scale in4 #a inch4 ,,question #bcd4 ,what is the effect on the admission of giving an eccentric with a small throw the same angular advance as one with a large throw1 and then reducing the lap of the valve so that the lead will be the same in both cases8 ,answer4 ,the admission and the cut-off will then occur at the same points of the stroke1 but the ports will not be opened so wide4 ,this is illustrated in fig4 #adc1 in which the paths of two eccentrics having the same throw as those in fig4 #adb are represented4 ,the centre1 a1 of the larger eccentric is represented in the same position in fig4 #adc as in fig4 #adb4 ,if a line is drawn from the centre of the larger eccentric to that of the axle1 and if the centre1 h1 of the smaller eccentric is located on the intersection of this line with the circle representing its path1 then the smaller eccentric will have the same angular advance1 but the linear advance measured by the distance o t will be only in4 ,if the valve have the same lap as in fig4 #adb1 its steam edges at the beginning of the stroke1 if the small eccentric is employed1 will occupy the position represented by the dotted lines ,a and ,b4 ,if these edges are cut off1 as shown by the full lines and shading1 then the valve will have the same lead as in fig4 #adb4 ,it is obvious1 too1 that if the smaller eccentric has the same angular advance it will reach the point v1 at which1 with the reduced lap1 the steam will be cut off1 at the same time that the centre1 a1 of the large eccentric will reach p1 at which point it cuts off the steam with the valve having the large lap4 ,there is1 however1 this difference in the distribution1 that in the one case the valve opens the port a distance equal to t s1 and in the other a distance equal to r b4 ,as o t is equal to the linear advance of the small eccentric1 or in41 and o s to half the throw of the eccentric1 or #a1 t s is equal to #a - #a in4 ,the distance r b1 as shown above1 is equal to #b - #a in41 so that the effect produced upon the admission of using an eccentric with a small throw and corresponding amount of lap is1 that the ports are not opened so wide as with an eccentric having a larger throw4 ,illustration3 ,fig4 #ade4 ,scale in4 #a foot4 ,,question #bce4 ,how do eccentrics with a short throw1 and valves with a corresponding amount of lap1 affect the admission with a link motion as compared with eccentrics having a larger amount of throw and greater lap of valve8 ,answer4 ,the chief difference is that the ports are not opened so wide for the same period of admission4 ,thus in fig4 #add is a series of motion-curves drawn with a model of a link motion like that illustrated in fig4 #ajc4 ,the eccentrics had #e in4 throw1 and the valve in4 lap outside and in4 inside4 ,fig4 #ade represents a series of curves1 drawn with the same arrangement of valve-gear1 excepting that the eccentrics had #c in4 throw and the valve in4 lap4 ,in both cases the curves represent the motion of the valve when cutting off at the same point of the stroke4 ,the following table will show the relative amount of opening of the port4 ,width of ,opening of ,steam-port4 --------------------------- ,point of ,eccentric ,eccentric ,cut-,off4#e in4 throw4#c in4 throw4 ----------------------------------- #f in4 in4 in4 #h #aj #ab #ae #ah #ba #afd #a ----------------------------------- #fd ,the valve throws over #a in4 at this point4 ,it will be seen from this that the eccentric with #e in4 throw gives a greater width of opening for every point of cut-off than the one with #c in4 throw4 ,for the higher admissions this is not important1 but when steam is cut off short it will be observed that the width of the opening is very small4 ,at high speeds the small opening is a great disadvantage4 ,,question #bcf4 ,has it been determined what amount of opening is required for given speeds of the piston8 ,answer4 ,not with any degree of accuracy4 ,it is customary to make the area of the ports about one-tenth that of the piston4 ,it is certain1 however1 that with steam-ports of this proportion an opening considerably less than their whole area is sufficient to maintain steam at boiler pressure in the cylinders4 ,one of the defects of the link motion is that the opening of the port is very small when the steam is cut off short4 ,it is best1 therefore1 to secure the largest practicable opening of the ports for the lower points of cut-off4 ,,question #bcg4 ,what are the proportions of the valves and eccentrics used in the ordinary practice in this country8 ,answer4 ,the following report made by a committee of the ,master ,mechanics' ,association will show the proportions used on thirty-five different railroads1 and is a fair indication of the common practice4 ,,table ,,showing ,,the ,,amount ,,of ,,lap1 ,,lead ,,and ,,travel ,,of ,,the ,,valves ,,of ,,locomotives ,,used ,,on #ce ,,of ,,the ,,railroads ,outside,inside ,,in ,,the ,,united ,,states ,,and ,,canada4 ,lap ,lap ---------------------------------------- ------------------------ in4 in4 ,for locomotives running express pass4 trains #be use #f #d #a accom4 #bj #aj #e heavy freight #ai #aa #e ,,table ,lead ,,showing ,,the ,,amount ,,of ,,lap1 ,,lead ,,and ,,travel ,,of ,,the ,travel in ,,valves ,,of ,,locomotives ,,used ,,on #ce ,,of ,,the ,,railroads of full ,,in ,,the ,,united ,,states ,,and ,,canada4 ,valve,gear ---------------------------------------- --------------------- in4 in4 ,for locomotives running express pass4 trains #be use #e #f #d #d #e accom4 #bj #e #aj #e #e #d heavy freight #ai #e #aa #d #e #d ,,question #bch4 ,what should be the width of the bridge between the steam and exhaust ports8 ,answer4 ,it is usually made about the same thickness as the sides of the cylinder1 in order to secure a good casting2 but sometimes it is necessary to make it wider1 in order to prevent steam from escaping from the steam-chest into the exhaust1 which is apt to be the case if a valve has little lap and a long travel4 ,,question #bci4 ,what determines the width of the exhaust-port8 ,answer4 ,the throw of the valve4 ,this will be clear if we refer to fig4 #adf1 which represents a valve with a travel of #e in4 ,it will be seen that when it is in the extreme position in which it is shown the width ,a of the opening of the exhaust-port is very small4 ,if this opening is contracted too much it will of course interfere with the free escape of the exhaust steam4 ,it is therefore best to make the exhaust-port so wide that with the greatest travel of the valve the width of its opening will be either quite or very nearly equal to the width of the steam-port4 ,illustration3 ,fig4 #adf4 ,scale in4 #a foot4 ,illustration3 ,fig4 #adh4 ,fig4 #adg4 ,scale in4 #a foot4 ,,question #bdj4 ,where is the reverse lever located and how is it constructed8 ,answer4 ,it is located on the foot-board#fe ,k ,k1 as shown in plate ,,ii4 ,it consists of a lever ,o1 ,o1 with the fulcrum at the lower end4 ,the reverse-rod e k1 which connects the lever with the vertical arm k of the lifting-shaft1 is attached above the fulcrum of the reverse lever4 ,figs4 #adg and #adh represent side and end views of the lever on an enlarged scale and with some of the details attached which are omitted on plate ,,ii4 ,c1 ,c are two curved bars1 which in this country are usually called quadrants1 but in ,england are called 7and more properly7 sectors4 ,these are placed on each side of the reverse-lever and are fastened to some portion of the engine4 ,they have notches1 n1 n1 n1 cut in them to receive the latch ,l1 which slides in a clamp1 ,h1 and holds the reverse-lever in the notches in which it is placed4 ,this latch is operated by a trigger1 ,d1 which is grasped by the locomotive runner when he takes hold of the handle ,a of the reverse-lever4 ,the trigger works on a pin1 ,e1 as a fulcrum and is attached to the latch by a rod1 r r4 ,when the trigger is pressed up against the handle1 the latch is raised out of the notches by the rod r r1 and is pressed into them again by the spring s when the trigger is released4 ,f is a set-screw which presses against a gib1 ,g1 and is intended to keep the latch tight and prevent the reverse-lever from shaking4 #fe ,the foot-board ,k ,k1 plates #b and #c1 is a platform for the locomotive runner and fireman to stand on and is located at the back end of the engine4 ,,question #bda4 ,how are the notches in the sector arranged8 ,answer4 ,they are usually arranged so that the steam will be cut off at some full number of inches of the stroke when the reverse-lever is in each one of the notches4 ,they are therefore located so that the steam will be cut off at #f1 #i1 #ab1 #ae1 #ah and #ba inches1 or at #f1 #h1 #aj1 #ab1 #ae1 #ah and #ba inches of the stroke4 ,a notch is also placed so as to hold the link in mid-gear4 ,in some cases as many notches as there is room for are put into the sectors4 ,the latter seems to be much the best plan1 as it gives more gradations in which the valve-gear can be worked1 and it is a matter of no consequence whatever in the working of an engine whether the steam is cut off at some full or some fractional number of inches of the stroke4 ,by referring to fig4 #add it will be seen how very great the difference of the distribution of steam must be1 as indicated by the #eth1 #fth and #gth motion-curves4 ,,question #bdb4 ,how long should the reverse-lever be8 ,answer4 ,the lever should be sufficiently long so that in throwing the link from full gear forward to full gear backward the handle ,a will move not less than four times the distance that the link is moved4 ,it is much better to give the end of the handle ,a five or even six times the motion of the link1 as there will then be a much easier action in reversing the engine4 ,this will also make it possible to use longer sectors1 and give room for more notches4 ,,question #bdc4 ,what provision is made in the reversing gear for overcoming or neutralizing the weight of the link and other parts of the valve-gear8 ,answer4 ,their weight is counterbalanced by the pressure of a spring of some kind4 ,in fig4 #ajc the two volute springs enclosed in a case1 ,h1 are used for this purpose4 ,these are compressed by the rod m1 which is attached to a short arm l1 on the reverse shaft ,a1 when the link is lowered1 and consequently the tension of the spring resists the weight of the link when the latter is down or in forward gear4 ,different kinds of springs are used for this purpose and sometimes are attached to the reverse-lever instead of to the lifting-shaft4 ,,question #bdd4 ,what is meant by 8setting0 a slide-valve8 ,answer4 ,it is to fasten the eccentrics in the right position on the axle and to adjust the length of the eccentric-rods and valve-stem so that the valves will give the required distribution of steam4 ,,question #bde4 ,how are the valves of a locomotive set8 ,answer4 ,after the wheels1 axles1 main connecting-rods and valve-gear are connected together1 put the rocker-arm in its middle position1 and lengthen or shorten the valve-stem so that the valve will be in the centre of the valve-face4 ,then place the crank on the forward centre and the full part of the forward motion eccentric above and that of the backward motion eccentric below the axle1 and fasten them to the axle temporarily by tightening up the set-screws4 ,then throw the link down until the block comes opposite to the end of the eccentric-rod1 and turn the wheels1#ff and at the same time1 observe whether the travel of the valve is equal to the throw of the eccentric and also whether it travels equally on each side of the centre of the valve-face4 ,if its travel is greater than the throw of the eccentric1 raise the link up2 if less1 lower it down until the two are just equal1 and then mark the position for the notches on the sections or quadrants to receive the latch of the reverse-lever4 ,if the valve does not travel equally on each side of the centre of the valve-face1 either lengthen or shorten the eccentric-rod1 as may be necessary4 ,repeat this operation for the backward motion1 by raising the link up until the block is opposite the end of the lower eccentric-rod4 ,after having done this1 go over the whole process again to see whether it is all correct4 ,now with the crank on the forward centre1 and the link in full gear forward1 loosen the set-screws in the forward eccentric1 and move it around the axle so that the valve will have the required lead and then fasten it again4 ,now raise the link up into full back gear1 and set the backward eccentric in the same way4 ,then turn the wheels so as to bring the crank on the back centre1 and observe whether the lead is correct for the back end of the cylinder4 ,if it is not1 lengthen or shorten the valve-stem or eccentric-rod so as to make the lead alike at both ends1 and if it is then too much or too little1 it can be increased or diminished by moving the eccentrics on the axle4 #ff ,this can be done by moving the engine on the track1 or by raising it off its wheels1 so that the latter can be turned without moving the former4 ,in some shops a pair of rollers is put in the track so that by placing the driving wheels on them they can be turned without any difficulty4 ,great care must be taken in setting valves to be sure that the cranks are exactly on the centres or dead points1 and it is impossible to set them in that position with sufficient accuracy from the motion of the piston or cross-head1 and therefore the centres of the crank-pins should always be set so as to conform to a line drawn through the centre of the cylinder and the axle4 ,when the cylinders are horizontal1 it is of course only necessary to place the cranks on a horizontal line drawn through the centre of the axle4 ,when the valves are set it should also be noticed whether the axle-boxes 7whose construction will be explained hereafter7 are in the centre of the jaws1 and if not they should be moved to the centre by driving wooden wedges between them and the frames1 either above or below1 as may be required4 ,the position of the boxes has a very material influence on the valve-gear4 ,if it is intended to lay off the notches on the sectors so as to cut off steam at certain definite points of the stroke1 these points should be laid off in the guides from the motion of the cross-head4 ,the latter being placed in any of the required positions at which steam is to be cut off1 the reverse-lever should then be moved so that the link will just close the admission port4 ,the lever can then be clamped to the sectors1 and the wheels turned so as to show whether its position is correct for each end of the stroke4 ,as before stated it is impossible to get the ordinary link-motion to cut off at exactly the same points at both ends of the cylinder1 but a very close approximation can be made by proportioning the different parts properly4 ,as has already been stated1 it is believed to be a much better plan to put as many notches in the sectors as possible1 than to locate them for certain definite points of the stroke4 ,in setting the valves of locomotives1 care must be taken to turn the wheels forward for the forward motion and backward for the backward motion4 ,after the valves are set the position of the eccentrics on the shaft should be marked1 so that in case they become loose on the road they can easily be set again4 ,it is usual1 too1 to mark the position of the valves with centre-punch marks on the valve-stem and on the stuffing-box of the steam-chest1 so that with a gauge made for the purpose the position of the valve can be determined without taking off the steam-chest cover4 ,in some cases the eccentrics are keyed on1 which is done after their position is determined by setting the valves4 ,the ends of the set-screws which are used to fasten the eccentrics should be cup-shaped and case-hardened1 so as to hold as securely as possible to the axle when they are screwed down4 ,,part ,,xii4 ,,the ,,running ,,gear4 ,,question #bdf4 ,what is meant by the running gear of a locomotive8 ,answer4 ,it means those parts1 such as the wheels1 axles and frames1 which carry the other parts of the engine4 ,as the ,germans express it1 it is the 8wagon0 of the locomotive4 ,,question #bdg4 ,how may the wheels be classified8 ,answer4 ,as driving and carrying or truck wheels4 ,,question #bdh4 ,what service must the driving wheels perform8 ,answer4 ,the driving wheels1 as indicated by their name1 8drive0 or move the locomotive on the track1 as was explained in answer to ,questions #fd1 #fe and #ff4 ,as their adhesion depends upon the pressure with which they bear upon the rails1 they must carry either a part or the whole of the weight of the engine4 ,,question #bdi4 ,what proportion of the weight of ordinary locomotives is usually carried on the driving wheels8 ,answer4 ,eight-wheeled 8,american0 locomotives1 which are most commonly used in this country1 have about two-thirds of their weight on the driving wheels4 ,,question #bej4 ,what is meant by the 8truck0 of a locomotive8 ,answer4 ,it means one or more pairs of wheels which are attached to a separate frame and to the locomotive by a flexible connection1 so that the axles are not held rigidly at right angles to the main frame1 but can assume positions which approximate to that of radii of the curves of the track4 ,in plates ,i1 ,,ii and ,,iii1 ,e ,e are the truck wheels1 b b the truck frame1 and y1 plate ,,ii1 and fig4 #dj1 the centre-pin1 around which the truck frame turns4 ,,question #bea4 ,what service does the truck perform8 ,answer4 ,it carries the weight of the front end of the locomotive1 and also guides it into and around curves and switches4#fg #fg ,a switch is a movable pair of rails1 by which a locomotive is enabled to run from one track to another4 ,,question #beb4 ,how does it perform the latter service8 ,answer4 ,it does it very much in the same way as the front wheels of an ordinary wagon enable it to turn around corners2 that is1 the truck wheels being attached to a separate frame1 which is connected to the locomotive by a centre-pin1 just as the front axle of an ordinary wagon is connected by the king-bolt1 can turn4 ,illustration3 ,fig4 #adi4 ,fig4 #aej4 ,scale1 inch #a foot4 ,illustration3 ,fig4 #aea4 ,,question #bec4 ,why are two pairs of wheels used on a locomotive instead of one1 as on an ordinary wagon8 ,answer4 ,because it is necessary to have one pair of wheels guide the other4 ,in an ordinary wagon the front axle is guided by the pole or shafts4 ,nearly every one knows the difficulty of moving a wagon when the pole or shafts are removed1 especially if it be pushed from behind4 ,the movement of the front axle is then uncontrolled1 and it is impossible to direct the motion of the vehicle4 ,the same thing would occur with a locomotive if a single pair of wheels were used1 and attached in the same way as the front axle of a wagon4 ,thus if a single pair of wheels were connected to a locomotive by a centre-pin1 a1 fig4 #adi1 so that the axle would be free to move around this pin1 then if one of the wheels should strike an obstruction1 say a stone1 s1 fig4 #aej1 there would be nothing to prevent the axle from being thrown into the position shown in fig4 #aej1 and the wheels would be quite sure to leave the track4 ,when two pairs of wheels are used and both axles attached to the same frame1 which is connected to the engine by a centre-pin1 s1 fig4 #aea1 between the two axles1 then the wheels in moving round the centre-pin must move around the centre s in arcs of circles1 m n1 m n1 described from the centre s4 ,these arcs1 it will be observed1 cross the rails4 ,now if the wheels should move in that direction1 the flange of one of them would come in contact with the rail and prevent it from moving any farther4 ,it is therefore evident that wheels arranged in that way can only move about the centre-pin as far as the curvature of the track will permit4 ,trucks are sometimes used with only one pair of wheels1 but the centre-pin is then placed some distance behind the centre of the axle1 or in the same relation to it that the centre s is to the axle a a in fig4 #aea4 ,it is evident that if the frame for such a truck turns around the centre-pin1 the wheels must move across the track in the same way as represented by the arcs m n1 in fig4 #aea4 ,the construction and operation of trucks with a single pair of wheels will be more fully explained hereafter4 ,illustration3 ,fig4 #aeb4 ,fig4 #aec4 ,scale ,inch #a ,foot4 ,fig4 #aed4 ,fig4 #aee4 ,fig4 #aef4 ,,question #bed4 ,why will a locomotive run around curves easier if the front axles are attached to a truck frame which is connected to the locomotive by a flexible connection8 ,answer4 ,because the truck axles can then assume positions which conform very nearly to the radii of the curves of the track1 and it is well known that if two or more axles1 each with a pair of wheels on it1 are attached to a frame with their centre lines parallel with each other1 as shown in fig4 #aeb1 they will roll in a straight line1 but if the centre lines of the axles are inclined to each other1 as shown in fig4 #aec1 the tendency will be to roll in a curve1 the radius of which will depend upon the degree of inclination of the axles to each other4 ,in order to make the wheels in fig4 #aeb roll on the curves a b and c d1 it will be necessary to slide them laterally a distance equal to that between the curves and the straight lines m o and p r1 and as the length of the outside curve is greater than the inside one1 if the wheels are fastened to the axles so they cannot turn on them and roll on the curves1 either the wheels on the inside or those on the outside must slip a distance equal to the difference in the length of the two curves4 ,considerable force will therefore be required to overcome the resistance due to the combined lateral and circumferential sliding of the wheels1 so that more power will be needed to make them roll in a curve than is necessary to make them roll in a straight line4 ,if1 however1 the axles are inclined to each other1 then the wheels will naturally roll on a curved path1 and it will not be necessary to slide them sideways to make them conform to such a path4 ,but if the wheels are all attached to the axles so that those on the same axle cannot turn independently of each other and are all of the same diameter1 then either the inside or the outside ones must slip1 because the path in which the outside ones roll is longer than the inside curve1 so that even if the axles are inclined to each other more power will be needed to roll the truck in a curved path than to roll the wheels shown in fig4 #aeb in a straight line4 ,it is1 however1 a fact that a cone or a portion of a cone like that shown in fig4 #aed will of itself roll on a curve4 ,it will do the same thing if the middle is cut away1 as indicated by the dotted lines in fig4 #aed and as shown in fig4 #aee4 ,if now the wheels are made so that their peripheries#fh form portions of a cone and the axles are inclined to each other as shown in fig4 #aef1 then there will be no slipping on the track1 because the outside wheel1 being larger in diameter than the inside one1 advances further in one revolution than the latter does1 and thus rolls on the longest path in the same time that the inside or smaller wheel does on the shorter one4 ,when this is the case1 such wheels will roll in a curve as easily as those in fig4 #aeb will in a straight line4 ,the degree of inclination of the axles and of the sides of the cone must1 however1 vary with the radius of the curve4 ,but if the axles are parallel to each other1 and the wheels conical1 as represented in fig4 #aeg1 they will not roll either in a straight line or in a curve without great difficulty1 because if they roll in a straight line1 the wheels on one side being larger in diameter than those on the other1 either the larger or the smaller ones must slip on the path in which they roll4 ,if they roll on a curve1 then each pair of wheels has a tendency to roll in a curve independent of the other1 and therefore the wheels must slip laterally if both pairs roll on the same track4 ,thus1 suppose two pairs of wheels1 a1 a1 and b1 b1 fig4 #aeg1 to be made conical and attached to a frame so that their axles are parallel to each other4 ,now each pair of such wheels will have a tendency to roll in circular paths1 a i1 a h1 and b k1 b j1 the centres of which are at m and n1 or at the apices of the cones of which their peripheries form a part4 ,if they are made to roll in circular paths1 c d1 e f1 described from a point g1 then each pair of wheels must slip laterally over the space between the paths a i1 a h1 in which they would naturally roll and that in which they are made to roll4 ,thus the wheel a would slide laterally the distance between the curve a h and a f1 and a that between a i and c d2 b would slide from b j to b f and b from b k to b d4 ,it will thus be seen that in order that two pairs of wheels may roll with equal ease in a straight line and in curves1 the wheels in the one case must be of equal diameters and the axles parallel1 and in the other case the wheels must be of unequal diameters and their axles be radial#fi to the curve4 ,this is equally true of any number of pairs of wheels4 ,if we have three1 four1 or any number of axles1 with wheels all attached to the same frame1 if their axles are parallel1 and the wheels of the same diameter1 they will roll in a straight line2 but if their wheels are conical and their axles radial1 they will roll in a curve4 #fh ,the periphery is the outside surface on which the wheel rolls4 ,this part of a wheel is usually called the 8tread40 #fi ,that is1 that their centre lines incline towards each other1 and if extended far enough would meet at the centre of the curve4 ,illustration3 ,fig4 #aeg4 ,scale ,in4 #a ,foot4 ,for the preceding reasons it is therefore sufficiently obvious that if a locomotive is to run on both straight and curved tracks1 on the former the wheels should be of the same diameter and the axles parallel1 and on the latter the wheels should be conical and the axles radial4 ,illustration3 ,fig4 #aeh4 ,fig4 #aei4 ,scale in4 #a foot4 ,,question #bee4 ,how are the wheels made so that in curves they will act as though they were of the conical form described and on a straight track all be of the same diameters8 ,answer4 ,the periphery or tread of each wheel is made conical1 but of the same size as the other1 and with the small diameter of the cone outside1 as shown in fig4 #aeh4 ,on a straight track if the position of the wheels on the rails is such that their two flanges are equally distant from the rails1 as shown1 then obviously at the points of contact with the rails the wheels are of the same diameter4 ,that is1 a is equal to b4 ,but in running on a curved track1 if the wheels are of the same diameter1 as has been shown1 they will roll in a straight line and consequently towards the outside of the curve4 ,the flange c--supposing it to be at the outside of the curve--will therefore roll towards the rail1 and consequently the outside wheel will rest on the rail at a point nearer the flange1 as shown in fig4 #aei1 where the diameter a is larger1 and the inside one further from the flange where the diameter b is smaller than at a and b in fig4 #aeh2 and consequently the action of the wheels is the same as though their peripheries were made of the form shown in fig4 #aeg4 ,,question #bef4 ,how are the axles of locomotives made to assume a position radial to the curves in the track8 ,answer4 ,this is only done approximately1 as the mechanical difficulties in the way of doing it perfectly are so great as to render it impracticable4 ,by attaching the truck to the locomotive by a flexible connection or centre-pin1 s1 as shown in fig4 #afj 7which represents a plan of the wheels of an ordinary locomotive71 it is plain that the truck axles e f and g h1 instead of remaining parallel to the driving-axles a b and c d1 will1 by turning around the centre-pin1 s1 adjust themselves to the curve so as to approximate as closely to radii as is possible for two axles which are held parallel to each other4 ,of course the further apart they are the greater will be their divergence from the position of radii1 and whether the tread of the wheels be cylindrical or conical the further apart their axles are the greater will be the divergence of the paths in which they would naturally roll from that of any curve on which they must roll4 ,thus1 if the axles were twice as far apart as they are represented in fig4 #aeg1 and in the position shown in the dotted lines l l and o o1 the wheels1 if they are conical1 would then naturally roll in curves drawn from the centres p and q4 ,if the wheels are cylindrical1 they would roll in straight lines4 ,in either case the divergence of their paths l s and l r from the curve of the track is greater than a h and a i1 the paths in which they would roll if their axles were nearer together4 ,this divergence increases with the distance between the axles1 and therefore the lateral slip of the wheels must be in the same proportion4 ,illustration3 ,fig4 #afj4 ,scale ,inch -- #a ,foot4 ,,question #beg4 ,is the resistance to rolling diminished by placing the truck axles nearer together8 ,answer4 ,it is1 within certain limits4 ,the nearer each other they are placed1 the closer will the centre-pin of the truck be to the centre of the axles4 ,the closer it is to the centre of the axle1 the greater is the tendency of the wheels to become 8slewed10 or to assume a diagonal position to the rails as represented in fig4 #aej1 and thus increase the resistance and also the danger of running off the track4 ,the increase of resistance from this cause1 after the axles reach a certain distance from each other1 is greater than the decrease from a closer approximation to the position of radii4 ,in ordinary locomotives it is necessary to place the truck wheels from #e ft4 #f in4 to #f ft4 apart1 in order to get the cylinders between them in a horizontal position4 ,this distance apart works very well in ordinary practice4 ,,question #beh4 ,what is meant by flange friction8 ,answer4 ,it is the friction of the flanges of the wheels against the head of the rails4 ,thus if two pairs of wheels1 a a1 b b1 fig4 #aea1 be placed on a curve and rolled in the direction of the dart1 the wheel a will roll towards the outside of the curve until the flange comes in contact with the rail4 ,as already explained1 if two axles are parallel to each other1 no matter whether the wheels are conical or cylindrical1 they must slip laterally in order to roll in a curved path4 ,as the flange must follow the curve of the rail1 it forces the wheel laterally and thus compels it to roll in the curved path into which the rail is bent4 ,as the wheel offers considerable resistance to sliding there is a corresponding pressure of the flange against the rail1 and consequently the revolutions of the wheel produce an abrasive action between the two4 ,this action is obviously increased with the distance between the axles1 because1 as has been shown1 the lateral slip of the wheels is then greater than when they are nearer together4 ,it is also obvious that if the wheels are parallel with the rails there will be no abrasive action of the flanges1 but that the greater the angle at which the wheels stand to the rails the harder will the flanges rub against the rails1 and the greater will be the flange friction4 ,with the aid of geometry it can very easily be proved that the farther apart two parallel axles are1 the greater will be the angle of the wheels to the rails on a curved track1 and1 therefore1 the greater will be their flange friction4 ,it must1 however1 be remembered that if the wheels are so close together that they are liable to become 8slewed10 or assume a diagonal position across the rails1 as shown in fig4 #aej1 the angle at which the wheels would stand to the rails would thus be very much increased4 ,it has therefore come to be a very generally recognized rule that the centres of axles should never be placed nearer together than the distance between the rails4 ,,question #bei4 ,is the flange friction of all the wheels of a truck the same on any given curve8 ,answer4 ,no2 of the front wheels obviously only the flange of the one on the outside of the curve comes in contact with the rail4 ,as the centrifugal force of the engine presses the back pair of wheels towards the outside of the curve1 the flange of the outside wheel alone comes in contact with the rail4 ,but as this wheel is constantly rolling away from the rail1 as shown by the dotted lines h g1 fig4 #aea1 obviously the friction of its flange is less than that of the front outside wheel1 which always rolls towards the rail4 ,the flange of the back inside wheel is carried outwards by the centrifugal force and also by the tendency of the wheels to roll on their largest diameters on a curve1 so that its flange will not touch the rail4 ,,question #bfj4 ,can the axles of driving wheels assume positions radial to the track8 ,answer4 ,in ordinary engines they cannot4 ,various plans have been devised for the purpose of enabling them to do so1 but it is only recently that they have met with any success4 ,some of these plans will be described hereafter4 ,it is1 however1 of less importance that the driving axles1 when they are behind the centre of the locomotive1 should assume positions radial to a curved track than that the front wheels should4 ,this is illustrated by a common road wagon1 as all know the ease with which such a vehicle can turn a corner if we run it with the front axle ahead1 and the difficulty of doing so when the back axle is in front4 ,in the case of a locomotive the reason for it is very much the same as that which makes the flange friction of the back wheels of a truck less than that of the front ones4 ,from fig4 #afj it will be seen that the outside driving-wheels1 when the engine is running with the truck in front1 are rolling from the rail and not against it4 ,as stated before1 the centrifugal force of the engine when in motion has a tendency to throw the wheels towards the outside of the curve4 ,it will also be noticed that the front driving axle is near the centre of that portion of the curve which lies between the centre s of the truck and the centre k of the back axle4 ,if it were in the middle between them1 it would be exactly radial to the curve2 being near the middle1 it approximates closely to that position1 and therefore the flange friction of its wheels is very slight4 ,it will be noticed that if the flange of the back or trailing-wheel on the inside of the curve were not kept away from the rail it would roll toward and impinge against that rail4 ,but it will be noticed that the flange of the front driving-wheel will come in contact with the inside rail before that on the back wheel can touch it4 ,for this reason1 and also on account of the effect of the centrifugal force exerted on the engine and the tendency of the wheels to roll on their largest diameters1 the flange of the inside back wheel is kept out of contact with the rail1 and as the back wheel on the outside of the curve rolls away from the rail there is very little friction of the flanges of the back driving-wheels4 ,it will also be noticed from fig4 #afj1 that if the radius of the curve is very short1 the bend of the rails between the back pair of driving-wheels and the centre of the truck is so great that the inside rail will press hard against the flange of the front or main driving-wheel next that rail4 ,this of course produces a great deal of friction1 and if the curve is excessively short the flange will mount on top of the rail and the tread of the opposite wheel will fall off from its rail4 ,for this reason the centre-pin of the truck is sometimes arranged so that it can move laterally1 that is cross-wise of the track4 ,in fig4 #afj the centre-pin is represented as having moved some distance from the actual centre of the truck1 which is represented with dotted lines4 ,the front wheels of locomotives are also sometimes made with wide 8flat0 tires1 that is1 tires without flanges1 so that there will be no friction against the one rail and no danger of falling off the other4 ,another action also takes place which facilitates the motion of the driving-wheels of ordinary engines around curves4 ,every one knows how easy the direction in which the front wheels of a common wagon can be controlled by taking hold of the end of the tongue or pole4 ,with the leverage which it gives the wheels and axle can easily be directed wherever it is desired4 ,a similar action takes place in an ordinary locomotive4 ,the front driving-axles are guided by the truck1 which is attached to the frame ten or twelve feet in front of the driving-axle1 and thus the track exerts a leverage to guide the movement of the driving-axles1 just as a common wagon can be guided by the pole4 ,if the locomotive is run backward1 then none of these advantages exist1 and the flange friction of the back driving-wheels is excessive4 ,engines such as construction locomotives1 which run backward as much as forward1 wear out the flanges of the back wheels very rapidly on crooked roads4 ,,question #bfa4 ,what is meant by the 8spread0 of the wheels or axles8 ,answer4 ,it is the distance between the centres of two axles4 ,,question #bfb4 ,what is the 8wheel-base0 of a locomotive8 ,answer4 ,it is the distance between the centres of the front and back or trailing-wheels4 ,on ordinary engines1 such as that illustrated in plate ,i1 it is the distance from the centre of the front truck to the centre of the back driving-wheels4 ,,question #bfc4 ,is the 8coning0 of the tread of the wheels of much practical importance8 ,answer4 ,there is great difference of opinion regarding it1 but even if its action is very beneficial1 the advantage is very soon lost1 owing to the wear of the wheels4 ,it is1 therefore1 believed that the advantage is more apparent in theory than in practice4 ,,question #bfd4 ,how are the driving-wheels of locomotives constructed8 ,answer4 ,they are made of cast iron with wrought-iron or steel tires around the outside4 ,fig4 #afa represents a perspective view of a pair of locomotive wheels and axle4 ,the central portion of the wheel1 that is the hub1 spokes and rim1 are cast in one piece4 ,usually the hub and the rim1 and sometimes the spokes1 are cast hollow4 ,the central portion of the wheel1 that is the part which is made of cast iron1 is called the wheel-centre4 ,illustration3 ,fig4 #afa4 ,,question #bfe4 ,how are the tires fastened on the wheel-centres8 ,answer4 ,the insides of the tires are usually turned out somewhat smaller than the outside of the wheel-centre4 ,the tire is then heated so that it will expand enough to go on the centre4 ,it is then cooled off1 and the contraction of the metal binds it firmly around the cast iron part of the wheel4 ,as an additional security bolts or set-screws1 a1 a1 fig4 #afa1 are screwed through the rim and into the tire to prevent it from slipping off in case it becomes loose4 ,in some cases the wheel-centre and the inside of the tire are turned conical1 and the tires are then put on cold and held on with hook-headed bolts1 ,c1 as shown in fig4 #afb1 which is a section of the tire and the rim of the wheel4 ,the wheel-centre is made largest on the inside4 ,as the strain against the flange of the tire is inward1 the cone of the wheel-centre resists this strain4 ,if it was curved or tapered the reverse way1 the strain would come on the bolts1 and it would also be impossible to remove the tires without first taking the wheels off the axles4 ,this method of putting on tires has the advantage that they can be removed quickly and without heating the tires4#gj #gj ,it is exclusively used on the ,baltimore and ,ohio ,railroad4 ,illustration3 ,fig4 #afb4 ,scale #c in4 #a foot4 ,,question #bff4 ,are there any standard sizes for the inside diameters of tires8 ,answer4 ,yes4 ,to avoid the great inconvenience arising from the diversity in the inside diameters of tires1 the ,american ,railway ,master ,mechanics' ,association has recommended that the inside diameter of tires should be made #cf1 #dj1 #dd1 #ej1 #ef and #fb inches4 ,the thickness for the first three sizes to be #c in4 and the last three #b in4 ,,question #bfg4 ,how are the driving-wheels fastened on the axles8 ,answer4 ,the hubs are accurately bored out to receive the axles1 and the latter are turned off so as to fit the hole bored in the wheel4 ,the axles are then forced into the wheel by a powerful pressure produced either with a hydraulic or screw press1 made for the purpose4 ,in order to prevent the strain upon the crank-pins from turning the wheels upon the axle1 they are keyed fast with square keys driven into grooves cut in the axle and in the wheel to receive them4 ,the ends of these keys are shown at b1 fig4 #afa4 ,,question #bfh4 ,how are the crank-pins made8 ,answer4 ,they are made of wrought iron or steel and accurately turned to the size required for the journals for the connecting-rods4 ,fig4 #afd represents one of the main crank-pins1 and fig4 #afc a back pin for an ,american engine4 ,the main pin has two journals1 one1 ,b1 to which the main connecting-rod is attached1 and the other1 ,a1 receiving the coupling-rod4 ,the back pin has only one journal1 ,a1 for the coupling-rod4 ,,question #bfi4 ,how are the crank-pins fastened to the wheels8 ,answer4 ,they are turned so as to fit accurately holes which are bored in the wheels1 and are usually 8straight0 or cylindrical4 ,the pins are then either driven in with blows from a heavy weight swung from the end of a rope1 or else pressed in with a screw or hydraulic press4 ,sometimes the holes are bored tapered or conical and the pins turned to the same form4 ,they are then ground in with emery and oil1 so as to fit perfectly1 and are secured by a large nut and key on the inside of the wheel4 ,illustration3 ,fig4 #afc4 ,fig4 #afd4 ,scale #a in4 #a foot4 ,,question #bgj4 ,what are the pieces ,a1 ,a1 fig4 #afa1 between the spokes of the wheel for8 ,answer4 ,they are called counterbalance weights1 and are put in the wheels to balance the weight of the crank-pins1 connecting-rods and pistons4 ,the principle of their action will be explained hereafter4 ,,question #bga4 ,on what part of the axle does the weight of the engine rest8 ,answer4 ,it rests on the driving-axle boxes ,l1 fig4 #afa1 which are placed just inside and close to the wheel4 ,illustration3 ,fig4 #afe4 ,,question #bgb4 ,what are the driving-axle boxes for and how are they made8 ,answer4 ,they are cast iron blocks1 ,l1 fig4 #afa1 which embrace and rest on the axle4 ,the part of the axle on which the box bears is called the journal4 ,each box has a brass bearing1 c1 fig4 #afe1 which bears on top of the journal and which is consequently exposed to the friction and wear4 ,fig4 #afe is a perspective view of a driving-box1 which shows what is called the oil-cellar1 d4 ,this is a receptacle underneath the axle which is filled with wool or cotton waste and saturated with oil for the purpose of lubricating the journal4 ,the oil-cellar is held in its position by two bolts1 f1 f1 which pass through it and the driving-box casting4 ,by removing the bolts the oil-cellar can easily be removed and the box can then be taken off the axle4 ,illustration3 ,fig4 #aff4 ,fig4 #afg4 ,scale in4 #a foot4 ,,question #bgc4 ,how are the truck wheels made8 ,answer4 ,they are made of cast iron1 usually in one piece4 ,figs4 #aff and #afg represent sections of two forms of wheels used for cars4 ,those used for locomotive trucks are similar to these1 excepting that they are usually a little smaller in diameter4 ,they are made with a disc or plate which unites the tire to the hub1 and in some cases they have ribs cast in the inside1 as shown in the two figures4 ,some are made with single and others with double plates1 as shown in the engravings1 and still others with spokes similar to the driving-wheels4 ,the tread of the wheel is hardened by a process called chilling4 ,this is done by pouring the melted cast iron into a mould of the form of the tread of the wheel4 ,the mould is also made of cast iron1 but being cold cools the melted iron very suddenly1 and thus hardens it somewhat as steel is hardened when it is heated and plunged into cold water4#ga #ga ,it should be mentioned here that it is only certain kinds of cast iron which will be hardened in this way1 or will 8chill10 as it is called4 ,the cause to which this chilling property is due is not known4 ,,question #bgd4 ,how are the boxes1 journals and journal-bearings of the truck-wheels made8 ,answer4 ,they are very similar to those for the driving-wheels1 their chief difference being that those for the truck-wheels are smaller than those for the driving-wheels4 ,,question #bge4 ,how are the frames for locomotives constructed8 ,answer4 ,the frames1 ,h ,h ,h1 plates ,i1 ,,ii and ,,iii1 are made of bars of wrought iron from #c to #d inches thick and about the same in width4 ,they are usually made in two parts1 the one at the back part of the engine1 to which the driving-boxes and axles are attached1 and the other at the front end1 to which the cylinders are bolted4 ,the back part1 or main frame1 as it is called1 is represented in figs4 #afh and #afi1 and consists of a top bar1 ,h ,h1 to which pieces1 a1 a1 b1 b1 called frame-legs1 are welded4 ,two of these form what is called a jaw1 which receives the axle-box1 as shown in fig4 #afi4 ,to the bottom of each jaw a clamp1 c1 is bolted to hold the two legs together4 ,the two legs1 a and b1 are united by a brace1 d d1 welded to the bottom of the legs4 ,a brace1 m1 unites the back end of the frame with the leg b1 and is welded to each4 ,the front part of each frame consists of a single bar1 e1 which is bolted to the back end1 as represented in figs4 #afh and #afi1 which show the construction clearer than any description would4 ,these front bars extend forward to the front end of the engine1 and a heavy timber1 called a bumper-timber1 ,e ,e1 plates ,i1 ,,ii and ,,iii1 extends across from one to the other and is bolted to each of them4 ,this timber is intended to receive the shock or blow when the locomotive runs against any object1 such as a car4 ,the cow-catcher or pilot1 ,s1 is fastened to this timber4 ,illustration3 ,fig4 #afh4 ,fig4 #afi4 ,scale in4 #a foot4 ,the front bar of the frames also has usually two lugs or projections forged on it1 between which the cylinders are attached4 ,the latter are securely held in their position by wedges1 which are driven in between the lugs and the cylinder castings4 ,the frames1 as already stated1 are made of wrought iron and are accurately planed off over their whole surface4 ,,question #bgf4 ,how are the frames fastened to the boiler8 ,answer4 ,as already stated1 they are fastened to the cylinders with wedges and bolts1 and as the cylinders are bolted to the smoke-box the frames are thus rigidly attached to the front end of the boiler4 ,in order to strengthen those portions of the frames which extend beyond the front of the smoke-box and to which the bumper-timber is attached1 diagonal braces1 r r1 plates ,i1 ,,ii and ,,iii are bolted both to the timber and to each of the frames at their lower ends4 ,the upper ends are bolted to the smoke-box4 ,other braces1 d1 plate ,,ii1 are also fastened to the frames and to the barrel of the boiler4 ,the frames are fastened to the fire-box by clamps1 ,i1 ,i1 plate ,i1 called expansion clamps4 ,these clamps embrace the frames so that the latter can slide through the former longitudinally4 ,there are also usually two diagonal braces not shown in plate ,,ii1 the upper ends of which are fastened to the back end of the shell of the fire-box at about the level of the crown-sheet1 and the lower ends to the back ends of the frames4 ,there are also usually transverse braces attached to the lower part of the frames1 thus uniting the two together4 ,the guide-yokes1 j j1 plate ,i1 are also usually bolted to the frames and to the boiler4 ,in many cases one only is used1 which extends across from one frame to the other and is fastened to the boiler4 ,,question #bgg4 ,why are the frames attached to the shell of the fire-box so as to slide longitudinally through the fastenings8 ,answer4 ,because when the boiler becomes heated it expands1 and if it could not move independent of the frames its expansion would create a great strain on both itself and the frames4 ,the fastenings to the fire-box are therefore made so that the frames can move freely through them lengthwise1 but in no other direction4 ,,question #bgh4 ,how much more will the boiler expand than the frames in getting up steam8 ,answer4 ,from to of an inch4 ,,question #bgi4 ,why is it necessary to support the engine on springs8 ,answer4 #gb;,because1 however well a road may be kept up1 there will always be shocks in running over it2 these occur at the rail joints and especially when the ballasting of the ties is not quite perfect4 ,these shocks affect the wheels first1 and by them are transferred through the axle-boxes to the frame1 the engine and the boiler4 ,the faster the locomotive runs1 the more powerful do they become1 and therefore the more destructive to the engine and road1 and consequently the faster a locomotive has to run the more perfect should be the arrangement of the springs4 #gb ,the above answer and much of the material referring to springs has been translated from 8,die ,schule des ,locomotivfhrers10 by ,messrs4 ,j4 ,brosius and ,r4 ,koch4 ,if we strike repeatedly with a hammer on a rail1 the latter is soon destroyed1 while it can bear without damage a much greater weight than the hammer lying quietly on it4 ,the axles1 axle-boxes and wheels strike like a hammer on the rails at each shock1 while the shock of the rest of the parts of the engine first reaches and bends the springs1 but on the rails has only the effect of a load greater than usual resting on them4 ,another comparison will make still plainer the lessening by the springs of the injurious effect which the weight of the boiler1 etc41 exercises on the rails4 ,a light blow with a hammer on a pane of glass is sufficient to shatter it4 ,if1 however1 on the pane of glass is laid some elastic substance1 such as india-rubber1 and we strike on that1 the force of the blow or the weight of the hammer must be considerably increased before producing the above-named effect4 ,if the locomotive boiler is put in place of the hammer1 the springs in place of the india-rubber1 and the rails in place of the glass1 the comparison will agree with the case above4 ,from this consideration it will be seen how important it is to make the weights of the axles1 axle-boxes and wheels as light as possible4 ,,question #bhj4 ,how are the driving-axle boxes arranged so that the weight of the engine will rest on springs8 ,answer4 ,they are arranged so as to slide up and down in the jaws4 ,springs1 ,b1 ,b1 fig4 #afi1 are then placed over the axle-boxes and above the frames4 ,these springs rest on -shaped saddles1 ,g1 ,g1 which bear on the top of the axle-boxes4 ,the frames are suspended to the ends of the springs by rods or bars1 g1 g1 g1 g1 called spring-hangers4 ,as the boiler and most of the other parts of the engine are fastened to the frames1 their weight is suspended on the ends of the springs1 which1 being flexible1 yield to the weight which they bear4 ,,question #bha4 ,how are the frames protected from the wear of the axle-boxes which results from their sliding up and down in the jaws8 ,answer4 ,the insides of the legs1 a1 a1 b1 b1 are protected with shoes or wedges1 h1 h1 which are held stationary1 and the box slides against the faces of the shoes1 thus wearing the shoe or wedge but not the frame4 ,,question #bhb4 ,why are the shoes usually made wedge-shaped8 ,answer4 ,they are made in that way so that when they become worn1 by moving one or both of them up in the jaws1 the space between them is narrowed and the lost motion is taken up4 ,they are moved by the screws i1 i4 ,if the boxes should become loose from wear1 it would cause the engine to thump at each revolution of the wheels or stroke of the piston4 ,,question #bhc4 ,how are the springs for the driving-wheels made8 ,answer4 ,they are made of steel plates which are placed one on top of the other4 ,these plates are of different lengths1 as shown at ,b1 ,b1 in fig4 #afi1 and are from #c to #d in4 wide and to thick4 ,the length of the springs measured from the centre of one hanger to the centre of the other is usually about three feet4 ,illustration3 ,fig4 #agj4 ,illustration3 ,fig4 #aga4 ,,question #bhd4 ,what determines the amount which a spring will bend under a given load8 ,answer4 ,the number of plates1 their thickness1 length and breadth1 and of course the material of which they are made4 ,this can be explained if we suppose we have a spring plate of a uniform thickness1 h1 and a triangular form1 of which fig4 #agj is a side view and #aga a plan1 and that it is clamped fast at its base1 b4 ,it is a well known mechanical law that any material of this form and under these conditions will have a uniform strength through its whole length to support any load1 ,p1 suspended at its end1 and also that it will bend or deflect in the form of an arc of a circle4 ,illustration3 ,fig4 #agb4 ,fig4 #agc4 ,fig4 #agd4 ,fig4 #age4 ,scale in4 #a foot4 ,,question #bhe4 ,how are locomotive springs usually made8 ,answer4 ,in locomotives the arrangement of springs is always such that they are either supported in the middle and moved at the two ends1 or such that they are supported at the two ends and loaded in the middle2 for our consideration it is indifferent which of the two kinds of springs is taken for the present illustration4 ,that shown in plan and elevation in figs4 #agb and #agc1 which is formed of a wide plate placed diagonally1 and which in reality consists of two such triangular pieces as were represented in fig4 #aga united at their bases m m1 and loaded at two opposite corners1 e and f1 would answer the requirements mentioned if the great breadth1 m m1 were not an obstacle4 ,this breadth is obviated by cutting the spring into several strips1 a a1 b b1 c c1 d d1 444 i1 fig4 #agc1 of equal width1 and placing these not side by side1 but one over the other1 as shown in figs4 #agd and #age4 ,in order that the separate strips and layers of the spring so made1 figs4 #agd and #age1 may not slip out of place1 the strips a a1 b b1 etc41 are made in one piece1 and all the plates are inclosed with a strap1 ,f1 figs4 #agf and #agg4 ,the plates1 instead of being cut from a piece like that represented in fig4 #agc1 are1 however1 made out of steel of the proper width1 and the ends1 instead of being cut off pointed as represented1 are sometimes drawn out thinner on the ends1 like the point of a chisel1 or oftener still cut off straight1 as shown in fig4 #agg4 ,illustration3 ,fig4 #agf4 ,fig4 #agg4 ,fig4 #agh4 ,scale in4 #a foot4 ,in order to hold the plates together a band1 ,f1 is put around the middle4 ,this is put on hot1 and becomes tight by contracting as it cools4 ,the centre of the spring has a hole drilled through it with a pin1 s1 fig4 #agh 7which shows a cross section of a spring71 to prevent the plates from sliding endwise4 ,the plates at each end usually have a depression1 a1 fig4 #agi 7which is a cross section of a plate on a larger scale than the preceding figure71 made in them on one side1 and a corresponding elevation1 b1 on the other4 ,the elevation on one plate fits into the depression on the other1 and thus prevents the plates from slipping sideways4 ,illustration3 ,fig4 #agi4 ,scale #f in4 #a foot4 ,illustration3 ,fig4 #ahj4 ,scale in4 #a foot4 ,,question #bhf4 ,how should springs be curved8 ,answer4 ,springs should be curved so that when they bear the greatest load which they must carry they will be straight4 ,if they are curved too much they are subjected not only to a strain which bends the plates1 but to one which has a tendency to compress them endwise4 ,thus if a spring like that represented in fig4 #ahj is bent into a half-circle1 it is obvious that the strain at the ends has no tendency at all to bend the plates1 but only to compress them endwise4 ,near the middle the strain will of course bend the spring4 ,in the one direction the spring is flexible and elastic1 and in the other it is not2 and as the strain of compression depends on the amount of curvature1 the greater the latter is1 the less flexibility and elasticity the spring will have4 ,springs are often given a double curve1 as shown in fig4 #aha4 ,this is not to be recommended1 because when a spring bends the plates must slide on each other4 ,if they have but a single curve1 they will do so and remain in contact through their whole length1 but if they have two curves they will separate and therefore 8gape10 as it is called4 ,illustration3 ,fig4 #aha4 ,scale in4 #a foot4 ,,question #bhg4 ,what is meant by the elasticity of a spring8 ,answer4 ,it is the amount which a spring will deflect or bend under a given load without having its form permanently changed4 ,if the bending is so great that the spring does not recover its original form when the load is removed1 then the strain to which it is subjected is said to exceed the limits of elasticity1 and if repeated often it will ultimately break the spring4 ,,question #bhh4 ,what is meant by the elastic strength and the ultimate strength of a spring8 ,answer4 ,the elastic strength is the strain it will bear without being strained beyond the limits of elasticity1 and the ultimate strength is the strain which will break it4 ,,question #bhi4 ,what determines the strength of a spring8 ,answer4 ,it depends of course 7#a7 upon the material of which the spring is made2 7#b7 its strength increases in proportion to the number of plates1 and 7#c7 to their width1 and 7#d7 in proportion to the square of their thickness1 and 7#e7 as the length diminishes4 ,thus1 if we wanted to double the strength of a spring like that shown in figs4 #agj and #aga1 it could be done in either of the following ways3 7#a7 by making it of material twice as strong2 7#b7 by putting another plate just like it on top2 7#c7 by doubling the width of the base b1 which would make the strength of the whole plate twice what it was before2 7#d7 by making the whole plate about four-tenths thicker1 which would increase its strength1 as already stated1 in proportion to the square of the thickness as #a4d #a4d #b nearly2 7#e7 by reducing the length to one-half what it is in fig4 #agj4 ,,question #bij4 ,what determines the elasticity of a spring8 ,answer4 7#a7 ,the material of which it is made2 with the same material the elasticity increases 7#b7 as the number1 and 7#c7 as the width of the plates diminishes1 and 7#d7 with the cube of the length1 and 7#e7 decreases with the cube of the thickness of plate4 ,thus1 supposing the plate in figs4 #agj and #aga to be in4 thick and the deflection d #b in42 the latter would be only half as much or #a in4 7#a7 if it were made of material twice as stiff1 or 7#b7 with two such plates1 or 7#c7 with one twice as wide at the base4 ,if 7#d7 the length were doubled1 the deflection would be equal to #b #b #b #h times what it was before1 or in proportion to the cube of the length4 ,if 7#e7 the thickness were doubled the deflection would be reduced in the same proportion1 and would be only one-eighth of #b in41 or in4 ,illustration3 ,fig4 #ahb4 ,fig4 #ahc4 ,scale in4 #a foot4 ,,question #bia4 ,what should be the proportion of the plates of a spring in relation to each other8 ,answer4 ,the lower plates should diminish regularly in their lengths4 ,the reason for this will be apparent from the fact which has already been stated1 that if a triangular plate of uniform thickness is clamped fast at its base1 it will1 if loaded at the end1 be of uniform strength throughout its whole length4 ,it is immaterial what the length of the base of such a triangle is1 if the two sides are of equal length and the thickness of the plate is uniform1 not only its strength but the amount of deflection or bending from any load will be equal all through its length4 ,if1 therefore1 we make a spring by cutting a plate formed of two such triangular pieces united at their bases into strips1 as has already been explained1 evidently the spring made of them will have a uniform strength throughout its whole length4 ,as the strips thus made diminish in length regularly1 it is evident that if the spring plates are made of steel rolled of the requisite width1 their length should be the same as that of those cut from the plate referred to above4 ,when this is the case the lower outline1 a b b a1 fig4 #ahc1 of the spring will1 when the spring is not bent1 be straight lines4 ,sometimes the lower outline of springs is made curved1 as shown in fig4 #ahb4 ,this gives too much strength near the strap ,f1 and too little near the ends4 ,in drawing springs1 therefore1 it is best to lay them out with the plates straight1 as shown in figs4 #ahb and #ahc1 and after determining the thickness1 drawing a straight line from the strap to the end of the longest plate will give the best form of the spring and the length of each of the plates4 ,it is necessary1 however1 to put a sufficient number of long plates in each spring to give it the required strength next to the attachment of the hanger4 ,sometimes one or more of these long plates are made heavier than the rest4 ,the evil of this method of construction will be apparent if it is remembered that the greatest permissible deflection up to the breaking of the spring decreases with the cube of the thickness of the plate and its strength increases with the square of the thickness4 ,now if we have a spring with say ten plates in4 thick and one on top in4 thick1 the thick plate will have a strength four times that of the thin plates1 but its elasticity will be only one-eighth that of the thin plates1 and therefore it will require eight times as much load to bend it any given distance as is needed to bend the thinner plates the same distance4 ,but its strength is only four times that of the thin plates1 so that for any given amount of elasticity the thick plate must bear twice as much load as it has strength to carry4 ,this shows what a great mistake is committed if some of the plates are made thicker than others1 a conclusion which is supported by practical experience1 as it is found that if the top plates are made thicker than others1 the thick ones break most frequently1 which is the necessary result of the supposed strengthening by increasing the thickness of the top plates4 ,,question #bib4 #gc;,how can we find by calculation the elasticity or deflection of a given steel spring8 #gc ,the following rules for calculating the proportion and strength of steel springs are from ,clark's ,railway ,machinery4 ,answer4 ,,by ,,multiplying ,,the ,,breadth ,,of ,,the ,,plates ,,in ,,inches ,,by ,,the ,,cube ,,of ,,the ,,thickness ,,in ,,sixteenths1 ,,and ,,by ,,the ,,number ,,of ,,plates3 ,,divide ,,the ,,cube ,,of ,,the ,,span#gd ,,in ,,inches ,,by ,,the ,,product ,,so ,,found1 ,,and ,,multiply ,,by #a4ff4 ,,the ,,result ,,is ,,the ,,elasticity ,,in ,,sixteenths ,,of ,,an ,,inch ,,per ,,ton ,,of ,,load4 #gd ,the span is the distance between the centres of the spring-hangers when the spring is loaded4 ,,question #bic4 ,how can we find the span due to a given elasticity and number and size of plates8 ,answer4 ,,by ,,multiplying ,,the ,,elasticity ,,in ,,sixteenths ,,per ,,ton ,,by ,,the ,,breadth ,,of ,,plate ,,in ,,inches1 ,,and ,,by ,,the ,,cube ,,of ,,the ,,thickness ,,in ,,sixteenths1 ,,and ,,by ,,the ,,number ,,of ,,plates3 ,,divide ,,by #a4ff1 ,,and ,,find ,,the ,,cube ,,root ,,of ,,the ,,quotient4 ,,the ,,result ,,is ,,the ,,span ,,in ,,inches4 ,,question #bid4 ,how can we find the number of plates due to a given elasticity1 span1 and size of plate8 ,answer4 ,,by ,,multiplying ,,the ,,cube ,,of ,,the ,,span ,,in ,,inches ,,by #a4ff2 ,,then ,,multiplying ,,the ,,elasticity ,,in ,,sixteenths ,,by ,,the ,,breadth ,,of ,,plate ,,in ,,inches1 ,,and ,,by ,,the ,,cube ,,of ,,the ,,thickness ,,in ,,sixteenths3 ,,divide ,,the ,,former ,,product ,,by ,,the ,,latter4 ,,the ,,quotient ,,is ,,the ,,number ,,of ,,plates4 ,,question #bie4 ,how can we find the working strength1 that is the greatest weight it should bear in practice1 of a given steel-plate spring8 ,answer4 ,,by ,,multiplying ,,the ,,breadth ,,of ,,plates ,,in ,,inches ,,by ,,the ,,square ,,of ,,the ,,thickness ,,in ,,sixteenths1 ,,and ,,by ,,the ,,number ,,of ,,plates2 ,,multiply1 ,,also1 ,,the ,,working ,,span ,,in ,,inches ,,by #aa4c3 ,,divide ,,the ,,former ,,product ,,by ,,the ,,latter4 ,,the ,,result ,,is ,,the ,,working ,,strength ,,in ,,tons 7,,of #b1bdj ,,pounds7 ,,burden4 ,,question #bif4 ,how can we find the span due to a given strength1 and number and size of plate8 ,answer4 ,,by ,,multiplying ,,the ,,breadth ,,of ,,plate ,,in ,,inches ,,by ,,the ,,square ,,of ,,the ,,thickness ,,in ,,sixteenths1 ,,and ,,by ,,the ,,number ,,of ,,plates2 ,,multiply1 ,,also1 ,,the ,,strength ,,in ,,tons ,,by #aa4c3 ,,divide ,,the ,,former ,,product ,,by ,,the ,,latter4 ,,the ,,result ,,is ,,the ,,working ,,span ,,in ,,inches4 ,,question #big4 ,how can we find the number of plates due to a given strength1 span and size of plates8 ,answer4 ,,by ,,multiplying ,,the ,,strength ,,in ,,tons ,,by ,,the ,,span ,,in ,,inches1 ,,and ,,by #aa4c2 ,,multiply ,,also1 ,,the ,,breadth ,,of ,,plate ,,in ,,inches ,,by ,,the ,,square ,,of ,,the ,,thickness ,,in ,,sixteenths3 ,,divide ,,the ,,former ,,product ,,by ,,the ,,latter4 ,,the ,,result ,,is ,,the ,,number ,,of ,,plates4 ,,question #bih4 ,how can we find the required amount of curvature or set of the spring before it is loaded8 ,answer4 ,,by ,,multiplying ,,the ,,elasticity1 ,,per ,,ton1 ,,in ,,inches1 ,,by ,,the ,,working ,,strength ,,in ,,tons2 ,,add ,,the ,,product ,,to ,,the ,,desired ,,working ,,compass4 ,,the ,,sum ,,is ,,the ,,whole ,,original ,,set1 ,,to ,,which ,,an ,,allowance ,,of ,,to ,,in4 ,,should ,,be ,,added ,,to ,,the ,,permanent ,,setting ,,of ,,the ,,spring4 ,,question #bii4 ,how are the spring-hangers attached to the ends of the springs8 ,answer4 ,a great variety of methods have been used4 ,the most common ones are those shown in fig4 #afi4 ,there the hanger embraces the spring at the ends1 g1 g1 7shown on an enlarged scale at a1 in figs4 #agf and #agg47 ,the end of the spring has two projections forged on its end to receive the upper end of the hanger1 which is made to fit the groove thus formed between the two projections4 ,the other end1 b1 of the spring1 figs4 #agf and #agg1 has an eye cut in it which receives the hanger b4 ,the latter is made of a single bar1 and also has an eye1 c1 to receive a key which sustains the weight suspended on the hanger b4 ,the back end of the front springs and the front end of the back springs are made in this way because they come on the side of the fire-box1 and if their width was increased by the thickness of the hanger1 as shown at a in fig4 #agg1 it would rub against and wear the outer shell of the fire-box4 ,,question #cjj4 ,how are the lower ends of the hangers attached8 ,answer4 ,the front hanger1 g1 fig4 #afi1 of the front spring1 and the back hanger1 g1 of the back spring have eyes and pins in their lower ends1 k1 as shown in the engraving4 ,the pins are supported by rubber springs1 l1 l1 which are held between two concave castings1 n1 k1 one of each of which rests against the frames4 ,the object of the rubber springs is to relieve the spring-hangers from sudden shocks and strains4 ,the benefit derived from their use is believed to be purely imaginary1 as the spring itself1 if sufficiently elastic1 should absorb the sudden shocks which the wheels and axles will convey to the hangers4 ,,question #cja4 ,why are the ends g1 g of the springs attached to the lever#ge ,a ,a8 #ge ,this lever is called an equalizing lever or beam1 or1 more briefly1 an equalizer4 ,answer4 ,because if there is a spring for every axle and the hangers are fastened to the frame1 then evidently the locomotive has as many points of support as it has axle-boxes4 ,every shock from the rails is transferred through the wheel and the axle to the nearest axle-box and the spring belonging to it1 and the latter must be made strong enough to receive and dispose of the whole of it4 ,if the adjacent hangers1 g1 g1 fig4 #afi1 of the adjoining springs1 ,b and ,b1 are connected by an equalizing lever1 ,a ,a1 which turns on the fixed point ,c1 then the shock which affects one wheel will be transferred first to the corresponding spring4 ,from this spring a part of the shock will be transferred to the frame by the hanger g1 and a part by the hanger g to the equalizer1 which will transfer the pressure to the adjoining spring ,b4 ,if by some unevenness of the road or a powerful oscillation of the locomotive1 a spring is momentarily burdened1 the equalizer thus causes the next wheel to receive part of this load4 ,the advantages of this arrangement are evident3 since the springs have to receive only a part of the shocks1 they can be made less strong and therefore more flexible4 ,the danger of running off the track and that of breaking axles1 springs and hangers1 is therefore reduced by the use of equalizing levers4 ,,question #cjb4 ,how are the equalizing levers constructed8 ,answer4 ,they are made of wrought iron and are supported in the centre by a fulcrum1 ,c1 which is fastened to the frame or boiler or both4 ,the spring-hangers g1 g are usually attached to the lever by eyes and keys4 ,sometimes eyes are made in the lever1 as shown in fig4 #afi1 and the hanger is inserted into the eye and held either with a key or else with projections which are forged on the hanger below the lever4 ,in other cases the hangers are made with an eye which embraces the end of the lever4 ,,question #cjc4 ,how is the distribution of weight of the engine affected by the equalizing levers8 ,answer4 ,the weight is equally distributed on all the driving-wheels4 ,this is apparent if it is observed that the weight suspended from each of the spring-hangers of each spring in fig4 #afi must be the same2 for if the weights in the two hangers1 g and g1 were unequal1 then the end of the spring which supports the heaviest weight would be drawn down until the pressure was equalized4 ,if the weights suspended from the two hangers1 g and g1 attached to the equalizing lever were unequal1 then the one supporting the greatest load would draw up its end of the equalizer until the weights were again in equilibrium4 ,illustration3 ,fig4 #ahd4 ,fig4 #ahe4 ,scale in4 #a foot4 ,another effect of the equalizing levers is that each side of the locomotive is supported in such a way that the action is the same as it would be if it was supported on one point4 ,if1 for example1 we have a heavy beam1 say a piece of timber like that shown by ,a ,b1 fig4 #ahd1 suspended at one point1 ,c1 in its centre1 to the middle1 a1 of a long spring1 ,d ,e1 the ends of which rest on two supports1 ,f and ,g1 it is evident that if the point of suspension is at the middle1 ,c1 of the timber and a of the spring1 the weight of the timber will rest equally on the two supports1 ,f and ,g1 and that the ends of the timber can move up or down or vibrate about the point of suspension1 ,c1 without affecting the distribution of weight on the supports1 ,f and ,g4 ,if1 now1 the timber is suspended from three points1 ,a1 ,c and ,b1 fig4 #ahe1 that is1 its middle and two ends1 as shown in fig4 #ahe1 the ends1 ,a and ,b1 being attached to the ends of the springs b c and d e1 the latter resting on the supports ,f and ,g1 and connected at their opposite ends to an equalizer1 f g1 whose fulcrum is at a1 it is evident that each of the end hangers must support one-half of that part of the weight of the timber between it and the middle1 and that the centre hanger must support one-half the weight between the middle and the two ends4 ,thus the hanger ,a b must support one-half the weight of the timber between ,a and ,c1 and ,b e must support one-half of that between ,b and ,c2 in other words1 the end hangers would each sustain one-fourth of the weight of the timber and the middle one-half of its weight4 ,if the weight of the timber is #a1jjj pounds1 the end hangers would each sustain #bej and the middle one #ejj pounds4 ,the weight of the middle of the timber is hung on the equalizer1 and one-half1 or #bej pounds of it is thus transferred to each of its ends f and g1 and thence to the hangers f c and g d1 and thus to the springs1 so that the ends1 c and d1 of the springs1 sustain a weight of #bej pounds1 therefore1 as the opposite ends also sustain the same weight1 it is evident that each of the springs bears a total load of #ejj pounds1 or one-half of the weight of the timber1 which is the same load they sustained in fig4 #afd4 ,if the ends of a timber supported as shown in fig4 #ahe are moved up or down about the centre point of suspension1 it is evident that the distribution of weight would not be affected any more than it was in fig4 #afd by a similar movement1 because if the ends of the timber move as shown by the dotted lines around the centre point of suspension ,c1 the end ,a will ascend as much as ,b descends4 ,the same thing is true of the ends b and e of the springs and of their opposite ends c and d1 and also of the ends of the equalizer1 so that when the timber1 springs and equalizer are in the position shown by the dotted lines1 it is in equilibrium1 just as it was when the timber was horizontal2 and therefore the weight on the supports is the same in both cases1 thus showing that the load ,a ,b can move about the centre of suspension when supported as shown in fig4 #ahe as freely as it can if arranged as shown in fig4 #ahd4 ,it therefore follows that in the distribution of the weight of each side of the locomotive on the wheels and on the track1 it may be regarded the same as though it was supported at one point1 which is the fulcrum of the equalizing-lever4 ,,question #cjd4 ,what advantage results from supporting the weight of the back part of the locomotive on two points8 ,answer4 ,if the back part of the locomotive rests on only two points and the front end on the centre of the truck1 then the whole weight of the engine will be sustained on three points4 ,now it is a well known fact that any tripod1 like that on which an engineer's level is mounted1 or a three-legged stool1 will adjust itself to any surface1 however uneven1 and stand firmly in any position2 whereas if there are more than three points of support1 if they are all of the same length the surface on which they rest must be a plane1 otherwise some of them will not touch4 ,all railroad tracks have inequalities of surface1 and therefore it is of the utmost importance that a locomotive should be able to adjust itself on its points of support to any unevenness of the track on which it must run4 ,this is possible only when the weight rests on three points of support4 ,illustration3 ,fig4 #ahf4 ,fig4 #ahg4 ,fig4 #ahh4 ,scale1 inch #a foot4 ,,question #cje4 ,how is the truck constructed8 ,answer4 ,it consists1 as has already been stated1 of two pairs of wheels4#gf ,these are attached to a frame1 b b1 plates ,i1 ,,ii and ,,iii4 ,the axles have boxes called truck-boxes1 and brass bearings similar to those used on the driving-axles4 ,these boxes work in jaws1 also similar to those on the main engine frame1 excepting that they have no attachment to prevent them from being worn by the motion of the boxes up and down in the jaws4 ,fig4 #ahf is a horizontal section1 fig4 #ahg a plan1 and fig4 #ahh a transverse section#gg of a truck4 ,the frame ,c ,d ,e ,f1 fig4 #ahg1 shown also at h h1 figs4 #ahf and #ahh1 is of rectangular form and is forged in one piece4 ,the legs f f which form the jaws for the boxes1 are bolted to the frame as shown in fig4 #ahf4 ,to the lower end of these legs a brace1 g g g1 is bolted1 which thus unites them together4 ,on each side one spring1 ,s ,f ,s1 is placed under the frame and in the reverse or inverted position to that of the driving-springs4 ,a pair of equalizing levers1 ,g ,g ,g1 is placed on each side of the truck1 one of them on the inside of the frame and the other on the outside1 as shown in the plan4 ,the ends of these equalizers rest on the top of the truck-boxes1 and the springs are attached to the levers at i i by the hangers1 j j4 ,the truck-frame rests on the top of the spring-strap1 ,f1 which is made of the form of an arc of a circle1 or 8rounded10 as it is termed by workmen1 so that it can move freely about the point of support4 ,it is evident that this arrangement of spring and equalizer operates in the same way as that employed for the driving-wheels in distributing the weight on each of the wheels1 and that the truck-frame is supported on two points1 k1 k1 figs4 #ahf and #ahg4 ,the weight of the front end of the engine rests on a cast iron centre-plate1 ,h ,h4 ,this centre-plate rests on four bars1 l l1 l l1 and m m1 m m1 two of which are bolted to the frame transversely and the other two longitudinally1 as shown in the plan4 ,these bars are elevated in the centre as shown in figs4 #ahf and #ahh4 ,the transverse bars are trussed with two corresponding bars1 n n1 fig4 #ahh1 below4 ,these truss-bars as they are called1 are bolted to the upper bars with bolts1 o1 o1 but are separated from the top-bars by distance pieces1 ,p1 ,p1 figs4 #ahf and #ahh4 ,the centre-plate ,h ,h1 called the lower centre-plate1 has an annular groove in it1 which receives a corresponding projection on the casting ,k ,k1 called the upper centre-plate1 which is bolted to the bed-plate of the cylinders1 as shown in plate ,,ii4 ,the upper centre-plate has a pin1 y1 called a centre-pin1 fig4 #ahf and plate ,,ii1 attached to it1 which passes through the lower centre-plate1 and has a key underneath the latter plate4 ,this key is intended to prevent the engine from 8jumping0 off of the truck on a rough track or in case of accident4 ,the annular groove and the projection which fits into it are intended to receive the strain which otherwise would bear against the centre-pin and would be liable to break or bend it4 #gf ,in some rare cases three pairs of wheels are employed for locomotive trucks4 ,six-wheeled trucks are very commonly used under passenger cars4 #gg ,the right half is a section through the centre of the axle1 or of ,g g1 of fig4 #ahf1 and the left half a section through the centre of the truck1 or on g g1 of fig4 #ahf4 ,from this description it will be seen that while the truck-frame rests on two points1 k and k1 the weight of the engine is supported by the centre-plate of the truck4 ,as the back part substantially rests on the centres of the two equalizers1 it will be seen that this distribution of the weight fulfills the conditions of the tripod1 or as it has been called1 the 8three-legged principle40 ,illustration3 ,fig4 #ahi4 ,fig4 #aij4 ,fig4 #aia4 ,scale in4 #a foot4 ,,question #cjf4 ,how are trucks arranged so as to give them lateral motion8 ,answer4 ,when this is done1 the lower centre-plate is usually suspended in some way from the truck-frame on links or hangers1 so that it can swing laterally4 ,one method of doing this is shown in figs4 #ahi1 #aij and #aia4 ,fig4 #aij is a front view1 fig4 #aia a plan1 and fig4 #ahi a transverse section of such an arrangement4 ,the centre-plate ,h ,h has cast with it an extension1 ,b ,b1 the ends of which are suspended on links1 ,l1 ,l1 called suspension-links1 the upper ends of which are attached to bars1 m1 m1 which are set edgeways and extend across the truck-frames4 ,it is evident that with this arrangement the lower centre casting can swing crosswise of the track on the links ,l1 ,l1 and that the front end of the engine will thus have a lateral motion independent of the truck4 ,,part ,,xiii4 ,,adhesion ,,and ,,traction4 ,,question #cjg4 ,what is meant by the 8adhesion0 of a locomotive8 ,answer4 ,it is the resistance which prevents or opposes the slipping of the driving-wheels on the rails1 and is due to the friction of the former on the latter4 ,,question #cjh4 ,on what does the amount of this friction depend8 ,answer4 ,like all friction it depends upon the weight or pressure of the surfaces in contact1 and consequently upon the load which rests on each wheel4 ,it also depends upon the condition of the rails1 and probably to some extent upon the material of which they and the tires on the wheels are made4 ,illustration3 ,fig4 #aib4 ,scale in4 #a foot4 ,,question #cji4 ,how much force is required to make the driving-wheels of a locomotive slip on an ordinary railroad track8 ,answer4 ,the force required to make them slip will1 as already stated1 vary very much with the condition of the rails4 ,if they are quite dry and clean it will require a force equal to about one-fourth the weight on the wheels4 ,that is1 supposing we have a wheel1 ,a ,b1 fig4 #aib1 attached to a frame which is fastened so that it cannot move1 and that the wheel rests on a rail and is loaded with say #aj1jjj pounds1 if now a rope or chain could be attached at a point1 ,b1 exactly at the tread of the wheel1 and carried over a pulley1 ,c1 then it would require a weight1 ,d1 of about #b1ejj pounds attached to the end of the rope to make the wheel slip4 ,if the rails were sanded1 the adhesion would be somewhat greater1 and if they were wet or muddy or greasy1 considerably less4 ,for ordinary circumstances the adhesion may safely be assumed to be one-fifth of the weight of the driving-wheels4 ,of course the total weight on all the driving-wheels must be taken in calculating the adhesion4 ,thus1 if a locomotive has four driving-wheels and each one of them bears a load of #aj1jjj pounds1 then the total weight on the driving-wheels1 or adhesive weight1 as it is called1 will be #aj1jjj #d #dj1jjj pounds1 and the adhesion will be #dj1jjj ------ #h1jjj pounds4 #e ,,question #caj4 ,what is meant by the tractive power of a locomotive8 ,answer4 ,it is the force with which the locomotive is urged in a horizontal direction by the pressure of the steam in the cylinders1 and which therefore tends to move the locomotive and draw the load attached to it4 ,the tractive power is of course due to the pressure of steam on the piston1 and therefore its amount is dependent upon the average steam pressure in the cylinder1 on the area of the piston1 and also on the distance through which the pressure is exerted1 or1 in other words1 on the stroke of the piston4 ,thus if we have a cylinder #af inches in diameter and two feet stroke and an average steam pressure of #ej pounds per square inch1 then as the area of such a piston would be #bja square inches1 the average pressure on it would be #bja #ej #aj1jej pounds1 and as each piston moves through four feet during one revolution of the wheels1 the number of foot-pounds of energy exerted by it would be #aj1jej #d #dj1bjj1 and for the two cylinders of a locomotive double that amount1 or #hj1djj foot-pounds4 ,now if the driving-wheels are five feet in diameter1 their circumference will be #ae4g feet1 and therefore the locomotive will move that distance on the rails during one revolution1 if the wheels do not slip4 ,the #hj1djj foot-pounds of energy is therefore exerted through a distance of #ae4g feet1 and therefore #hj1djj ------ #e1aba pounds1 #ae4g which is the force exerted through each foot that the circumference of the wheel revolves and the locomotive moves4 ,if the wheels were only half the diameter1 or #b feet1 then their circumference would be #g4he feet and the tractive power would be #hj1djj ------ #aj1bdb pounds1 #g4he or double what it was before4 ,it will be seen1 then1 that the tractive force of a locomotive is dependent upon 7#a7 the average steam pressure in the cylinders1 7#b7 the area1 7#c7 the stroke of the pistons1 and 7#d7 the diameter of the driving-wheels4 ,,question #caa4 ,how is the tractive power of a locomotive calculated8 ,answer4 ,,by ,,multiplying ,,together ,,the ,,area ,,of ,,the ,,piston ,,in ,,square ,,inches1 ,,the ,,average ,,steam ,,pressure ,,in ,,pounds ,,per ,,square ,,inch ,,on ,,the ,,piston ,,during ,,the ,,whole ,,stroke1 ,,and ,,four ,,times ,,the ,,length ,,of ,,the ,,stroke ,,of ,,the ,,piston1#gh ,,and ,,dividing ,,the ,,product ,,by ,,the ,,circumference ,,of ,,the ,,wheel4 ,the result will be the tractive power exerted in pounds4 ,the adhesion must of course always exceed the tractive force1 otherwise the wheels will slip4 #gh ,this length may be taken in feet1 inches or any other measure1 but in making the calculation the circumference of the wheel must be taken in the same measure as the stroke of the piston4 ,,question #cab4 ,how is the locomotive made to advance by causing the wheels to revolve8 ,answer4 ,the pressure of steam in the cylinders is exerted in one direction against the piston1 and in the opposite direction against the cylinder head1 as shown in fig4 #aib1 in which the steam is represented by the dotted shading in the back end of the cylinder1 and the direction of the pressure by the darts s1 s4 ,the pressure against the piston is communicated by the connecting-rod to the crank-pin ,e1 and that on the cylinder-head is carried to the axle by the frame ,f ,f1 and the direction of the two forces is indicated by the two darts1 a and b4 ,we may now regard the spokes of the wheels as acting as levers1 and assume that the fulcrum is either at the centre ,g of the axle1 or at ,b1 the point of contact of the wheel with the rail4#gi ,we will assume that it is at the centre ,g of the axle and for the sake of even figures that the wheel is six feet in diameter and cylinders have two feet stroke4 ,we will also suppose that the engine is supported so that the wheels do not touch the rails1 and that a chain or rope passing over a pulley ,c is attached to the wheels at ,b and with a weight at ,d4 ,we now have a force1 a1 of #aj1jjj pounds exerted on the crank-pin1 or at the end of the short arm ,e ,g of the lever ,e ,g ,b4 ,as ,e ,g is one foot and ,g ,b three feet long1 #aj1jjj would be balanced by #aj1jjj #a ---------- #c1ccc pounds1 #c at ,b4 ,in other words1 it would require #c1ccc pounds suspended from the chain at ,d to resist the strain at ,e4 ,but when this is the case1 the pressure of the axle at the fulcrum1 in the direction of the dart c1 is equal to the pressure against the crank-pin ,e added to that exerted by the weight ,d at ,b1 or #aj1jjj #c1ccc #ac1ccc pounds4 #gi ,the question whether the centre of the axle or the point of contact with the rail is the fulcrum of the lever in this case has been the subject of much animated discussion and contention4 ,as the word fulcrum means 8a point about which a lever moves10 it is believed that the dispute is due simply to a difference in the meaning assigned to the word fulcrum4 ,if we regard the fulcrum as the point which is fixed in relation to the locomotive1 then it is at the centre of the axle1 but if we refer it to the surface of the earth1 then it is at the top of the rail4 ,as the pressure against the axle in the opposite direction1 b1 is only #aj1jjj pounds1 there will be an unbalanced force of #c1ccc pounds acting in the direction of the dart c1 and tending to move it that way4 ,as the axle is attached to the locomotive frame1 this force will of course have a tendency to move the whole machine1 and is really the tractive force of the engine4 ,if1 on the other hand1 we regard the point of contact ,b of the wheel with the rail as a fulcrum1 we have a force of #aj1jjj pounds acting against a lever1 ,e ,g ,b1 four feet long4 ,there would therefore be a force1 c1 of #aj1jjj #d ---------- #ac1ccc pounds #c exerted at ,g1 and as the pressure in the direction of the dart b is only #aj1jjj1 there would be an unbalanced strain of #ac1ccc - #aj1jjj #c1ccc pounds acting against the axle in the direction of the dart c1 or1 in other words1 there is #c1ccc pounds more of force pulling the axle forward than there is pushing it backward4 ,when the crank-pin is below the axle1 in the position shown in fig4 #aic1 then if the centre of the axle is regarded as the fulcrum we have a pressure of #aj1jjj pounds pushing against the front cylinder-head1 which is transferred to the axle by the frames1 and acts in the direction of the dart c1 and we also have a pressure against the crank-pin ,e in the direction of the dart a4 ,now #aj1jjj pounds at ,e would exert a force of #aj1jjj #a ---------- #c1ccc pounds #c at ,b and #aj1jjj #b ---------- #f1fff pounds #c at ,g in the direction of b4 ,but the pressure on the cylinder-head pulls against the axle ,g in the direction c with a force of #aj1jjj1 so that the excess of strain in the direction b will be equal to #aj1jjj - #f1fff #c1ccc pounds4 ,if we regard ,b as the fulcrum1 the calculation is exactly the same1 as #aj1jjj pounds at ,e exerts a force at ,g equal to #aj1jjj #b ---------- #f1fff pounds1 #c and the difference between it and the pressure exerted by the strain against the front cylinder-head is the force which urges the axle and with it the locomotive forward4 ,it will be seen1 then1 that it is immaterial which point is regarded as the fulcrum1 as the result of the calculations is exactly the same4 ,illustration3 ,fig4 #aic4 ,scale in4 #a foot4 ,it must not1 however1 be hastily supposed from what has been said that the total pressure against the axle can be greater than its resistance to the pressure4 ,as soon as the one exceeds the other it will move4 ,but supposing that it requires a force equal to #c1ccc pounds to draw a train coupled to the engine1 as soon as the difference between the force exerted against the axle by the piston to move it forward and that which presses it back exceeds #c1ccc pounds1 the locomotive will move the train4 ,if it continues to exceed it the speed of the train will be accelerated and thus the resistance which holds the engine back and that which pushes it forward will always be equal4 ,,question #cac4 ,does the fact that the piston is working from the end of a longer lever ,e ,g ,b1 fig4 #aib1 when the crank-pin is above the axle1 enable the locomotive to start a heavier train than when the crank-pin is below the axle and the piston is working against a shorter lever1 ,g ,e ,b1 fig4 #aic8 ,answer4 ,no2 because1 as has already been shown1 the pressure against the axle is the same in both cases4 ,it is in fact only during the forward stroke that the pressure on the crank-pin moves the engine forward4 ,the forward pressure which is exerted by the crank-pin at the axle is then greater than that exerted against the latter in the opposite direction by the cylinder-head and frames4 ,it is this excess of crank pressure which moves the engine and which is the tractive force during the forward stroke4 ,during the backward stroke the piston is pushing the axle backward1 and the pressure against the front cylinder-head is pulling it forward4 ,the latter then exceeds the former1 and the difference between the two is the force which moves the engine forward4 ,as has been shown1 this difference is the same in both positions of the crank1 and therefore the locomotive can not from this cause pull more when the crank is above the axle than when it is below4 ,,part ,,xiv4 ,,internal ,,disturbing ,,forces ,,in ,,the ,,locomotive4 ,,question #cad4 ,what are the internal disturbing forces in a locomotive8 ,answer4 ,they are3 #a1 the momentum of the parts which have a reciprocating motion2 #b1 those due to the varying pressure of the steam in the cylinder-heads2 #c1 those caused by the thrust of the connecting-rods against the guide-bars2 and #d1 those produced by unbalanced revolving parts4 ,,question #cae4 ,how can the effects of these disturbing forces be neutralized8 ,answer4 ,by putting counterweights1 ,a1 ,a1 fig4 #afa1 in the driving-wheels opposite the crank-pins4 ,the motion of these will then be in the reverse direction to that of the weight of the parts attached to the crank-pins1 and the motion of the one will thus1 to some extent1 at least1 neutralize the disturbing influence of the other4 ,,question #caf4 ,can the weight of these counterweights be calculated for any locomotive8 ,answer4 ,it can probably be calculated1 but it is an exceedingly complicated problem1 and one about which there is much difference of opinion4 ,the difficulty is also increased by the fact that while counterweights may be heavy enough for one speed1 they may be too heavy or too light for a slower or faster speed1 and quite disproportioned when the engine is not working steam4 ,the following rules are given in 8,clark's ,railway ,machinery10 and are perhaps sufficiently close to find a first approximation to the requisite position and weight of the counterweights2 but the final adjustment should be made by trial4 ,this can be done by suspending the locomotive by chains attached to the four corners of its frame1 and setting the machinery in motion at the speed it is intended to run4 ,by attaching a pencil to one or to each of the four corners of the frame1 and arranging it so that it will mark on a horizontal fixed card1 a diagram will be drawn1 being usually an oval1 which will show the amount and form of the oscillations4 ,the counterweights can then be adjusted so that the diagram drawn by the pencil is reduced to the least possible size4 ,when the adjustment is successful1 the diameter of the diagram is reduced to about of an inch4#hj ,another and simpler1 but less accurate1 way is to place a pail or other vessel filled with water on the front of the engine and run the locomotive on a smooth track at a high speed1 and adjust the counterweights so that the least amount of water will be spilled4 #hj ,rankine's ,treatise on the ,steam ,engine4 ,,question #cag4 ,how can the centre of gravity of a counterweight in one segment be found8 ,answer4 ,,by ,,cutting ,a ,,wooden ,,templet ,,of ,,uniform ,,thickness ,,to ,,the ,,form ,,of ,,the ,,surface1 ,,and ,,freely ,,suspending ,,it ,,by ,,one ,,of ,,the ,,corners1 a1 ,,as ,,in ,,fig4 #aid2 ,a ,,plummet-,,line1 ,p a1 ,,dropped ,,from ,,the ,,same ,,point ,,of ,,suspension ,,in ,,front ,,of ,,the ,,templet ,,will ,,intersect ,,the ,,centre ,,line b c ,,at ,,the ,,centre ,,of ,,gravity ,c4 ,illustration3 ,fig4 #aid4 ,,question #cah4 ,how can the centre of gravity of a counterweight in three segments be found8 ,answer4 ,,find ,,the ,,centre ,,of ,,gravity ,c1 ,,fig4 #aie1 ,,of ,,one ,,of ,,the ,,counterweights1 ,,as ,,above2 ,,through ,c ,,strike ,,an ,,arc ,,from ,,the ,,centre1 a1 ,,of ,,the ,,wheel1 ,,crossing ,,the ,,centre ,,lines ,,of ,,the ,,other ,,segments ,,at ,,their ,,centres1 ,c ,c2 ,,draw ,c ,c ,,meeting ,a ,b ,,at ,d1 ,,and ,,set ,,off ,d ,e1 ,,one-,,third ,,of ,,the ,,interval ,d ,c4 ,,then ,e ,,is ,,the ,,common ,,centre ,,of ,,gravity ,,of ,,the ,,three ,,segments4 ,illustration3 ,fig4 #aie4 ,,question #cai4 ,how can the centre of gravity of a counterweight in two segments be found8 ,answer4 ,this is required when the crank is opposite to a spoke1 as in fig4 #aif4 ,,find ,,the ,,centre ,,of ,,gravity1 ,c1 ,,of ,,one ,,segment ,,as ,,before1 ,,and ,,by ,,an ,,arc ,,find ,,the ,,other ,,centre ,c2 ,,draw ,c ,c1 ,,cutting ,a ,b ,,at ,d1 ,,which ,,is ,,the ,,common ,,centre ,,of ,,gravity4 ,illustration3 ,fig4 #aif4 ,,question #cbj4 ,how can the centre of gravity of a counterweight in four segments be found8 ,answer4 ,,find1 ,,as ,,before1 ,,the ,,centres ,c1 ,c1 ,c1 ,c1 ,,fig4 #aig1 ,,of ,,the ,,segments2 ,,draw ,c ,c ,,and ,c ,c1 ,,cutting ,,the ,,line ,a ,b2 ,,bisect ,,the ,,interval ,,so ,,inclosed ,,at ,e ,,for ,,the ,,common ,,centre ,,of ,,gravity4 ,illustration3 ,fig4 #aig4 ,,question #cba4 ,how is the counterweight for outside-cylinder engines with a single pair of driving-wheels calculated8 ,answer4 ,,find ,,the ,,total ,,weight1 ,,in ,,pounds1 ,,of ,,the ,,revolving ,,and ,,reciprocating ,,masses ,,for ,,one ,,side1 ,,namely1 ,,the ,,piston ,,and ,,appendages1 ,,connecting-,,rod1 ,,crank-,,pin ,,and ,,crank-,,pin ,,boss2 ,,multiply ,,by ,,the ,,length ,,of ,,crank ,,in ,,inches1 ,,and ,,divide ,,by ,,the ,,distance ,,in ,,inches ,,of ,,the ,,centre ,,of ,,gravity ,,of ,,the ,,space ,,to ,,be ,,occupied ,,by ,,the ,,counterweight4 ,,the ,,result ,,is ,,the ,,counterweight ,,in ,,pounds1 ,,to ,,be ,,placed ,,exactly ,,opposite ,,to ,,the ,,crank4 ,question #cbb4 ,how is the counterweight for outside-cylinder engines with coupled driving-wheels calculated8 ,answer4 ,,find ,,the ,,separate ,,revolving ,,weights1 ,,in ,,pounds1 ,,of ,,crank-,,pin1 ,,crank-,,pin ,,boss1 ,,coupling-,,rods ,,and ,,connecting-,,rod1 ,,for ,,each ,,wheel1 ,,also ,,the ,,reciprocating ,,weight ,,of ,,the ,,piston ,,and ,,appendages1 ,,and ,,half ,,the ,,connecting-,,rod2 ,,divide ,,the ,,reciprocating ,,weight ,,equally ,,between ,,the ,,coupled ,,wheels1 ,,and ,,add ,,the ,,part1 ,,so ,,allotted1 ,,to ,,the ,,revolving ,,weight ,,on ,,each ,,wheel2 ,,the ,,sums ,,so ,,obtained ,,are ,,the ,,weights ,,to ,,be ,,balanced ,,at ,,the ,,several ,,wheels1 ,,for ,,which ,,the ,,necessary ,,counterweight ,,may ,,be ,,found ,,by ,,the ,,preceding ,,rule4 ,question #cbc4 ,how are the counterweights constructed8 ,answer4 ,they are usually made of cast iron1 so as to fill or partly fill the spaces between the spokes of the wheel1 as shown at ,a ,a in fig4 #afa4 ,each of the segments consists of two pieces1 one of which is put in from the outside of the wheel and the other from the inside4 ,the two are then bolted together with bolts1 which are shown in the above figure4 ,in some cases the counterweights are cast solid with the wheels1 and in others1 cavities are cast in the wheels which are filled with lead1 which is poured in when melted4 ,some locomotive builders make the rims and spokes of the wheels hollow and fill them with lead opposite to the crank-pins4 ,it is difficult1 however1 to get the required weight in such wheels unless they are of large diameter4 ,,question #cbd4 ,what effect has the strain on the draw-bar1 when the engine is pulling a load1 upon the distribution of the weight on the wheels8 ,answer4 ,it has the effect of pulling the back end of the engine down1 and1 as it is balanced on the fulcrums of the equalizing levers1 it at the same time lifts up the front end4 ,in this way the harder a locomotive is pulling the greater will be the weight which is thrown on the driving-wheels1 and that on the truck will be correspondingly diminished4 ,the higher the draw-bar is above the rails the greater will be the tendency to pull the engine down behind and up in front4 ,,part ,,xv4 ,,miscellaneous4 ,,question #cbe4 ,what is the sand-box1 ,v1 plates ,i and ,,ii for1 and how is it constructed8 ,answer4 ,it is intended to carry a supply of dry sand1 which is scattered on the rails in front of the driving-wheels when the latter are liable to slip4 ,this is done by two pipes1 e1 e1 plate ,i1 one on each side of the engine4 ,they lead from the sand-box to within a few inches of the rail4 ,at the upper end and inside the sand-box they each have a valve which is operated by a lever which is connected to the cab by a rod which enables the locomotive runner to open or close the valve at pleasure4 ,the sand-box is usually made of sheet iron with a cast iron base1 and a top of a more or less ornamental design4 ,it also has an opening on top through which the sand is supplied to the box4 ,this opening has a loose cover to exclude rain and dirt from the sand4 ,the sand-box is usually located on top of the boiler in front of the front driving-wheels4 ,,question #cbf4 ,what is the bell ,u for8 ,answer4 ,it is used for giving signals of the starting or approach of the engine4 ,it also is located on top of the boiler and is usually hung on a cast iron frame and rung with a rope connecting it with the cab4 ,,question #cbg4 ,what is the weight of an ordinary locomotive bell8 ,answer4 ,from #ej to #ajj pounds4 ,,question #cbh4 ,what is a locomotive head-light8 ,answer4 ,it is a large lamp1 ,t1 plates ,i and ,,ii1 placed in front of the locomotive to signal its approach at night and also to illuminate the track for the locomotive runner4 ,illustration3 ,fig4 #aih4 ,scale #a in4 #a foot4 ,,question #cbi4 ,how is a head-light constructed8 ,answer4 ,the lamp has what is called an ,argand burner2 that is1 a burner with a hollow cylindrical wick1 through the centre of which a current of air circulates1 which thus supplies the flame with a larger quantity of air than is possible if the latter can come in contact with the former only from the outside4 ,the result is that the combustion is much more brilliant than with ordinary burners4 ,in order to throw all the light on the track the burner is placed inside of a concave reflector1 a b c1 fig4 #aih1 which is of a parabolic form4 ,one of the peculiarities of this form of reflector is that if a light is placed in its focus f the rays will be reflected from its surface in parallel lines4 ,thus1 let a b c1 fig4 #aih1 represent a section of such a reflector4 ,now1 if a light be placed in the focus f the rays will strike against the reflector1 be thrown in the direction of the dotted lines f #a x1 f #b x 444 f #i x1 etc41 and thus be thrown directly in front of the engine4 ,the reflectors are usually made of copper and plated with silver4 ,the lamps and reflectors for head-lights are inclosed in a rectangular case which is supported on two brackets bolted to the front of the smoke-box4 ,on these brackets a wooden shelf is fastened on which the head-light rests4 ,,question #ccj4 ,what are the running-boards and hand-rails8 ,answer4 ,the running-boards are planks1 i i1 plate ,i1 placed on each side of the boiler to enable the locomotive runner or fireman to go from the cab to the front end of the engine when it is running4 ,the hand-rails1 m m m1 are brass or iron pipes attached to the top of the boiler and extending from the cab to the smoke-box1 and are placed there1 as their name indicates1 to support or for a hand-hold for persons on the running-board4 ,,question #cca4 ,what provision is made for removing from the track such obstacles as cattle or fallen rocks1 which may be in front of locomotives8 ,answer4 ,what is called a cow-catcher or pilot1 ,s1 plates ,i and ,,ii1 is attached to the front of the locomotive4 ,this is usually made of wood1 and consists of a triangular frame at the bottom which is supported about four inches above the tops of the rails4 ,straight pieces of wood of about #b #d inches section are fastened to this frame and also to a horizontal piece which is bolted to the bumper-timber ,e4 ,these pieces arranged in this way and only a few inches apart give to the cow-catcher a peculiar curved form somewhat resembling that of the mould-board of a plow1 which is very well adapted for throwing any obstacles from the track4 ,sometimes these pieces are placed horizontally instead of being inclined up and down4 ,cow-catchers are also in some cases made of round iron bars or angle iron4 ,they are always bolted securely to the bumper-timber and strengthened by strong iron braces attached to the bottom frame at the front and back4 ,these braces are usually fastened at the other end to the bumper-timber1 but are sometimes attached to the bed-plates of the cylinder4 ,there is also usually a strong pushing-bar attached with a bolt and hinged joint to the bumper-timber4 ,this is shown in plates ,,ii and ,,iii in the position it occupies when not in use4 ,it is used in pushing cars1 as very often there is not room for the pilot under the end of the car4 ,in using it is raised up1 and the front end is then coupled to the draw-head of the car4 ,illustration3 ,fig4 #aii4 ,,question #ccb4 ,what is the foot-board or foot-plate of a locomotive8 ,answer4 ,it is a wrought or cast iron plate which extends across and rests upon the two frames at the back part of the locomotive and behind the boiler1 and on which the locomotive runner and fireman stand4 ,it also unites the two frames very securely1 and furnishes an attachment for the draw-bar4 ,the foot-board is often made much heavier than is necessary for strength1 in order to increase the weight1 and thus the adhesion1 on the driving-wheels4 ,it is a fact often not suspected that any weight placed on the back end of an ordinary locomotive will increase the load on the driving-wheels by an amount considerably greater than that of the weight itself4 ,the reason of this is that the locomotive rests on the centre of the truck and the centres of the equalizers1 and therefore the weight1 if applied to the back end of the engine1 gains considerable leverage4 ,this will be clear if we take a beam1 ,a ,b1 and rest it on two supports1 m and n1 fig4 #aii4 ,if now we put a weight ,w on the end1 overhanging the point of support1 the weight which will rest on n will be equal to that of ,w multiplied by its distance ,c from m and divided by the distance ,d between m and n4 ,thus if a foot-board weighs #a1jjj pounds1 and its centre of gravity is #e feet behind the centre of the equalizer1 and the latter #ad feet from the centre of the truck1 then the weight thrown on the driving-wheels will be equal to #a1jjj #ai ------------- #a1cic pounds4 #ad ,the same thing is of course true of any other weight placed on the back end of the engine4 ,,question #ccc4 ,what are the 8wheel-guards0 of a locomotive8 ,answer4 ,they are sheet iron covers over the upper half of the periphery or tread of the wheels1 and are placed there to protect the engine from the dirt and mud which adhere to the wheels and are then thrown off on the machinery by the centrifugal force4 ,,question #ccd4 ,what are 8check0 or 8safety chains80 ,answer4 ,there are two kinds of such chains1 the one attached to the trucks and frames of the locomotive and the tender4 ,the object of these chains is to prevent the trucks from turning around and getting crosswise of the track if the trucks should leave the rails4 ,the other kind of safety chains connects the engine to the tender1 so that1 in case the draw-bar or coupling-pins should break1 the two will not separate4 ,great care should be exercised to attach the truck chains so as to be strong enough to resist the strains to which they will be subjected in case the trucks run off the track4 ,the grossest carelessness and ignorance are often shown in the construction of these parts4 ,,part ,,xvi4 ,,screw-,,threads1 ,,bolts ,,and ,,nuts4 ,,question #cce4 ,how must the screws of bolts and nuts be made1 in order to fit each other8 ,answer4 ,each size of screw must be made of exactly the same diameter1 and their threads of the same form and proportions and pitch4 ,,question #ccf4 ,what is meant by the 8pitch0 of a thread8 ,answer4 ,it is the distance the thread progresses lengthwise of the screw in one revolution4 ,thus if a single-threaded screw has one-eighth of an inch pitch1 it means that the threads are of an inch apart measured from the centre of one thread to the centre of that next to it1 and therefore there are eight threads to each inch in length of the screw4 ,,question #ccg4 ,what is meant by a 8single-threaded0 screw8 ,answer4 ,it means a screw with but one thread instead of two or more4 ,thus if we take a string and wind it around a pencil1 it will represent a single-threaded screw1 and if we take two or three strings and wind them parallel to each other1 they will represent a double or treble-threaded screw4 ,the latter kinds are seldom or never used on locomotives1 so that in the following discussion only single-threaded screws will be referred to4 ,illustration3 ,fig4 #bjj4 ,full ,size4 ,,question #cch4 ,what is the usual form of the threads of screws8 ,answer4 ,the most common is what is called the ,v-thread1 represented in fig4 #bjj1 which is made sharp at both the top and bottom4 ,if such a thread for one screw is made very pointed and that for another is blunt1 it is plain that the nut for the one will not fit the other accurately1 and also that if a nut has eight threads to the inch1 it will not fit on a bolt with nine4 ,owing to the fact that1 until within a few years1 no common standard has been agreed upon for the form1 proportions or pitch of screws there has been very great diversity in these respects in the screws which have been used in the construction of locomotives and other machinery4 ,in #ahfd the inconvenience and confusion from this cause became so great that it attracted the attention of the ,franklin ,institute of ,philadelphia1 and a committee was appointed by that association to investigate and report on the subject4 ,that committee recommended the adoption of the ,sellers system of screw-threads and bolts1 which was devised by ,mr4 ,william ,sellers1 of ,philadelphia4 ,this same system was subsequently adopted as the standard by both the ,army and ,navy ,departments of the ,united ,states1 and then by the ,master ,mechanics' and ,master ,car ,builders' associations1 so that it may now be regarded1 and in fact is called1 the ,united ,states standard1 but the design is due to ,mr4 ,sellers4 ,,question #cci4 ,in establishing a standard system of screws and threads1 what is the first thing which must be determined8 ,answer4 ,the number of threads to the inch1 or the pitch of the threads for screws of different diameters4 ,illustration3 ,fig4 #bja4 ,full size4 ,,question #cdj4 ,what is the standard for the number of threads to the inch for the different sized screws of the ,sellers system8 ,answer4 ,the number of threads with their other proportion is given in the table at the end of this chapter on page #cdh4 ,,question #cda4 ,what is the form of the thread of this standard8 ,answer4 ,the form is shown in fig4 #bja1 and is similar to the ,v-thread1 excepting that it is flattened at the top and bottom4 ,,question #cdb4 ,what are the reasons for the adoption of this form of thread8 ,answer4 ,it has already been pointed out that if a screw is made with a 8blunt0 thread it will not fit a nut with very acute or 8sharp0 threads2 or1 if the thread of the bolt was acute and that in the nut obtuse1 they would fit imperfectly4 ,it is therefore necessary in a standard system to fix upon the angle which the sides of the thread shall bear to each other4 ,this in the ,united ,states standard system was determined by ,mr4 ,sellers at #fj degrees1 because that angle is easily laid off without special instruments#ha and is perhaps as good as or better than any other form for the threads4 #ha ,this can be done by drawing a circle of any diameter1 and subdividing the circumference into six equal parts with the radius4 ,lines1 drawn from the points of division to the centre will have an inclination of #fj degrees to each other4 ,it is obvious that if a tool is ground with its sides at an angle of #fj degrees to each other1 if the point is made sharp after a very little use it will be worn more or less so that the bottom of the thread will not be cut perfectly sharp1 and therefore it will be difficult to make bolts and nuts with sharp threads fit each other accurately4 ,it is also plain that the sharp edge of a thread gives very little strength to the screw1 and yet diminishes that of the bolt very materially4 ,it will also be impossible to measure the diameter of the screw at the bottom of the thread if it is made sharp1 as its depth will vary as the point of the tool wears1 and it is almost impossible to measure the diameter of such a screw accurately with ordinary calipers4 ,a sharp-edged thread in a bolt is also very liable to be injured and bruised by coming in contact with other objects4 ,to obviate these evils the standard threads are therefore made flat on the top1 and it is evident that a similar shape at the bottom will give increased strength to the bolt as well as conform to and fit the thread in the nut4 ,to give this form requires only that the point of the cutting tool shall be taken off1 and then it is evident this form of thread can be cut in a lathe with the same tool and in the same manner as the sharp thread4 ,the width of the flat top and bottom should of course bear a definite proportion to the size or pitch of the thread4 ,illustration3 ,fig4 #bjb4 ,,question #cdc4 ,what are the proportions of the standard threads8 ,answer4 ,the rule given by ,mr4 ,sellers for proportioning the thread is as follows3 8,,divide ,,the ,,pitch1 ,,or1 ,,what ,,is ,,the ,,same ,,thing1 ,,the ,,side ,,of ,,the ,,thread1 ,,into ,,eight ,,equal ,,parts2 ,,take ,,off ,,one ,,part ,,from ,,the ,,top ,,and ,,fill ,,in ,,one ,,part ,,in ,,the ,,bottom ,,of ,,the ,,thread3 ,,then ,,the ,,flat ,,top ,,and ,,bottom ,,will ,,equal ,,one-,,eighth ,,of ,,the ,,pitch1 ,,the ,,wearing ,,surface ,,will ,,be ,,three-,,quarters ,,of ,,the ,,pitch ,,and ,,the ,,diameter ,,of ,,screw ,,at ,,bottom ,,of ,,the ,,thread ,,will ,,be ,,expressed ,,by ,,the ,,formula3 diameter - #a4bii ------------------------ no4 threads per inch40 ,in order to make the form and proportions of this standard thread as plain as possible1 we have had an enlarged diagram1 fig4 #bjb1 engraved1 so as to represent the different parts clearly4 x represents the pitch1 d the diameter of the screw in inches1 v the number of threads to the inch1 n the diameter at bottom of thread1 m the width of back part of thread at the top and bottom1 and s the length of the side of thread4 ,from ,mr4 ,sellers' rule the following formul can be deduced3 #a4bii n d - ----- v x m --- #h #cx s ---- #d ,from this rule any thread can be constructed1 it being only necessary to know the pitch or number of threads to the inch4 ,this1 with all the dimensions of the standard threads for bolts from to #b inch diameter1 is given in the table on page #cdh4 ,for practical use in the shop a gauge like that shown in fig4 #bjc will be found most convenient for grinding the tools to the proper form for making the standard screws4 ,with this gauge the screw-cutting tool can first be ground to the proper angle by fitting it to the deepest notch1 and the requisite quantity should then be taken off the point by fitting it to the notch representing the form of thread for the sized bolt or number of threads to the inch which it is intended to cut4 ,wherever this standard for threads is used1 if any pretense at all is made to accuracy of workmanship1 careful attention should be given to the form and proportion of the threads as well as to the number to the inch4 ,in buying taps and dies the purchaser should see that they conform in every respect to the standard1 and in making specifications for new work similar care should be exercised to secure the true standard1 form and proportion of screws4 ,in many shops the workmen who have the care of those tools are entirely ignorant of the peculiarities of the ,sellers system1 and have only the vague idea that so long as they get the proper number of threads to the inch they are doing all that is necessary to secure uniformity4 ,unless1 therefore1 some care is exercised to insure accuracy of workmanship in this department1 the adoption of a 8standard0 for screws will not insure the advantages which would result from uniformity of screws and threads4 ,illustration3 ,fig4 #bjc4 ,full size4 ,,question #cdd4 ,how thick must a nut be1 measuring lengthwise of the bolt1 so that the thread in the nut will be of equal strength to that of the bolt8 ,answer4 ,its thickness must be equal to the outside diameter of the screw4 ,,table ,,giving ,,proportions ,,of ,,the ,,united ,,states ,,or ,,sellers ,,standard ,,system ,,of ,,screw-,,threads4 ,diameter of screw at the,width of top ,outside root of the and bottom of diameter,number of thread in thread in of screw threads decimals of decimals of in inches per inch an inch an inch ---------------------------------------- --- #bj 4#ahe 4#jjfb #ah 4#bdj 4#jjgd #af 4#bid 4#jjgh #ad 4#cdd 4#jjhi #ac 4#djj 4#jjif #ab 4#ded 4#jajd #aa 4#ejg 4#jaac #aj 4#fbj 4#jabe #i 4#gca 4#jach #a #h 4#hcg 4#jaef #a #g 4#idj 4#jagh #a #g #a4jfe 4#jagh #a #f #a4afj 4#jbjh #a #f #a4bhd 4#jbjh #a #e #a4chi 4#jbbg #a #e #a4dia 4#jbej #a #e #a4faf 4#jbej #b #d #a4gab 4#jbgg ,,part ,,xvii4 ,,tenders4 ,,question #cde4 ,what are locomotive tenders for8 ,answer4 ,they carry a supply of fuel and water for locomotives while they are running4 ,,question #cdf4 ,how are they usually constructed8 ,answer4 ,their construction is represented in figs4 #bjd1 #bje and #bjf4 ,fig4 #bjd is a side view1 fig4 #bje a longitudinal section1 and fig4 #bjf a plan of an ordinary tender1 which consists of a frame1 ,a ,a ,a ,a1 made of wood or iron1#hb mounted on a pair of trucks1 ,t1 ,t4 ,the top of the frame is covered with planks1 ,b1 ,b1 which form the floor of the tender4 ,on top of this floor a sheet-iron tank1 ,c ,c ,c1 is placed1 which carries the supply of water4 ,this tank is made somewhat in the form of a letter 1 as shown in the plan4 ,it is made in this way so that the space between the two branches1 ,c1 ,c1 or 8legs10 as they are called1 will give room for fuel4 ,around the upper edge of the tank a sheet-iron rim1 ,d ,d1 is riveted1 so as to prevent the fuel from falling off when it is filled up above the top of the tank4 #hb ,the frame represented in the engraving is made of wood4 ,in the plan it is shown by dotted lines4 ,,question #cdg4 ,how is the tank filled with water8 ,answer4 ,there is a round opening1 ,e1 called a man-hole1 on top4 ,into this the end of a leather or canvas hose is introduced1 which is attached to a stationary tank1 at a water station1 and a stream of water is then allowed to flow through the hose into the tank of the tender4 ,,question #cdh4 ,how is the water conducted from the tender to the engine8 ,answer4 ,to each side of the front end of the tank1 one end of a piece of rubber hose1 ,f ,f1 is attached1 which is connected at the other end to the pipe on the engine which supplies the pump with water4 ,the opening inside the tank through which the water flows to the hose is covered with a valve1 which is not shown in the engraving1 but which is operated by a lever or handle1 ,g4 ,the valve is covered with a hood or strainer1 perforated with small holes1 which is intended to prevent dirt from entering the hose and thus getting into and obstructing the pump4 ,the hose is connected to the supply pipe by a screw-coupling similar to that used with ordinary fire-engine hose4 ,,question #cdi4 ,how are the flat sides of the tank strengthened so as to resist the pressure and weight of the water8 ,answer4 ,they are sometimes braced or stayed with rods or bars1 a1 a1 and h1 h1 fig4 #bje1 extending from one side to the other and from the top to the bottom1 and angle or iron is also riveted to the sides to stiffen them4 ,,question #cej4 ,how is the tender connected to the engine8 ,answer4 ,by the draw-bar1 ,h1 and coupling-pin1 o1 fig4 #bje1 and also by the safety chains1 d4 ,illustration3 ,fig4 #bjd4 ,scale inch #a foot4 ,illustration3 ,fig4 #bje4 ,scale inch #a foot4 ,illustration3 ,fig4 #bjf4 ,scale inch #a foot4 ,,question #cea4 ,in what respect do the tender trucks differ from the engine truck8 ,answer4 ,chiefly in having the journal-bearings and frames outside of the wheels4 ,illustration3 ,fig4 #bjg4 ,scale in4 #a inch4 ,illustration3 ,fig4 #bjh4 ,scale in4 #a inch4 ,,question #ceb4 ,why are the bearings placed outside instead of inside8 ,answer4 ,because they are then more accessible than if they are inside1 and the oil-boxes on the axles can be entirely closed over the ends of the axles1 so that no oil can leak out1 whereas if the boxes are inside1 they must be left open at both ends4 ,when the boxes are on the outside1 they can be oiled1 or a journal-bearing can be removed and a new one put in its place1 with much less difficulty than if the boxes were on the inside of the wheels4 ,the only reason why the bearings of engine truck-axles are placed inside the wheels is because they would be in the way of the cylinders if they were outside4 ,,question #cec4 ,how are the axle-boxes for the tender axle constructed8 ,illustration3 ,fig4 #bji4 ,scale in4 #a inch4 ,answer4 ,their construction is similar to that of a car axle-box1 the standard form of which is represented in figs4 #bjg1 #bjh and #bji4 ,fig4 #bjg is a section lengthwise of the axle1 fig4 #bjh a section crosswise of the axle1 and fig4 #bji a sectional plan4 ,a is the journal of the axle1 which is inclosed by a cast iron box1 ,k ,k1 which is open in front and at the back4 ,the front has a cover1 ,h1 which is either fastened by a spring1 as shown in the illustrations1 or is bolted to the box4 ,the axle enters the box from the back1 ,i1 and has either a wood or leather packing1 ,j ,j1 called a dust-guard1 to keep the dust from getting in and the oil from leaking out of the box4 ,d is a brass journal-bearing1 which rests against a cast iron bearing piece or key1 ,e1 which is put in so that by removing it through the opening ,f ,f1 the brass bearing can be raised up high enough to clear the collar1 ,g1 on the end of the axle and thus be removed in the same way4 ,the lower portion1 ,l1 of the box under the axle is usually filled with cotton or woolen waste saturated with oil4 ,this constantly presses against the axle1 and thus keeps it oiled4 ,,question #ced4 ,how are the tender trucks constructed8 ,answer4 ,they are made of various patterns1 some of which have wooden frames and in other cases the frames are made of iron4 ,the truck illustrated in our engraving1 figs4 #bjd and #bje1 is made of iron and is very similar to the engine truck1 excepting1 as already stated1 the frames are outside instead of inside of the wheels4 ,,question #cee4 ,how is the tender supported on the trucks8 ,answer4 ,it rests on the centre of the front truck and on a bearing1 n1 fig4 #bjd1 on the frames on each side of the back truck4 ,this arrangement gives three bearing points1 the advantages of which have already been explained4 ,a truck which supports the load which it carries in the centre is said to be centre-bearing1 and if the load is carried on each side1 side-bearing4 ,,question #cef4 ,how are the brakes attached to the tender8 ,answer4 ,they are attached usually to the back truck alone1 but in some cases to both trucks1 and are operated by a wheel1 ,n1 fig4 #bjd1 and a shaft which extends below the tender frame and on which a chain attached to the brakes is wound4 ,,question #ceg4 ,how much water and coal does an ordinary tender carry8 ,answer4 ,a tender for a thirty-ton engine carries from #a1ejj to #b1jjj gallons of water and three to four tons of coal1 and weighs from #dj1jjj to #de1jjj pounds loaded4 ,an engine of this kind and its tender therefore weigh about #ajj1jjj pounds1 which1 being even figures1 can easily be remembered4 ,,part ,,xviii4 ,,friction ,,and ,,lubrication4 ,,question #ceh4 ,what is meant by friction8 ,answer4 ,friction is the resistance between two bodies in contact which opposes the sliding of the one on the other4 ,thus if a brick is placed on a board with a slight inclination1 it will not slide because the friction between them1 or the resistance opposed to motion1 is greater than the force exerted by the weight of the brick to move it downward4 ,if1 however1 the inclination of the board is increased sufficiently so that a larger proportion of the weight of the brick urges it downward1 then the friction will be overcome1 and it will slide4 ,when the brake-blocks of a car are pressed against the wheels1 they produce friction1 which resists the revolving motion of the wheels and will ultimately stop the car2 and when the weight of an engine is supported on the driving-wheels and they rest on the rails1 the friction between them1 as has already been pointed out1 resists their slipping on each other1 and thus enables a locomotive to exert tractive force4 ,friction also resists the turning of an axle on its journal and therefore makes the tractive force of the locomotive necessary to move a train of cars4 ,,question #cei4 ,on what does the amount of friction depend8 ,answer4 ,the amount of friction of two bodies in contact depends 7#a7 ,,upon ,,the ,,pressure ,,of ,,the ,,one ,,on ,,the ,,other1 ,,and ,,is ,,independent ,,of ,,the ,,area ,,of ,,the ,,surfaces ,,in ,,contact2 7#b7 ,,on ,,the ,,nature ,,of ,,the ,,materials ,,in ,,contact2 7#c7 ,,on ,,the ,,nature ,,of ,,the ,,substance1 ,,such ,,as ,,oil ,,or ,,other ,,lubricant1 ,,which ,,is ,,interposed ,,between ,,them4 ,thus1 a brick will slide down an inclined board as easily if it is laid on its broadest side as it will if placed edgewise2 and if a cast iron plate1 say #aj inches square1 is planed and scraped1 so as to be as nearly a perfect plane surface as it is possible to make it1 it will1 if loaded with say a hundred pounds weight1 slide on a similar true surface as easily as another plate with half as much area and loaded with the same weight4 ,a shaft resting against a long bearing will require no more power to turn it than would be needed if the bearing was short4#hc #hc ,in fact1 ordinarily less power is required to turn it if the bearing is long than if it is short1 the reasons for which will be explained hereafter4 ,,question #cfj4 ,what is meant by the 8co-efficient of friction80 ,answer4 ,it is the proportion which the resistance to sliding motion bears to the force pressing the surfaces together4 ,thus a smooth1 clean and dry cast iron plate loaded with #ajj pounds will require a force of about #ae pounds1 or fifteen one-hundredths of the weight or pressure of the plates1 to slide them on each other4 ,the co-efficient of friction is therefore said to be #j4ae1 and with any other weight or pressure on the plates we could determine the force required to slide them on each other by multiplying the pressure by the co-efficient of friction4 ,thus1 if the plates were loaded with #bej pounds1 the force required to slide the one on the other would be equal to #bej 4#ae #cg4e pounds4 ,the co-efficient of friction1 however1 varies for different materials4 ,thus1 while the co-efficient of friction between two pieces of smooth1 clean and dry cast iron is #j4ae1 that of a piece of brass on cast iron1 under similar conditions1 is #j4bb1 and of two pieces of wood about #j4d4 ,,question #cfa4 ,what is the effect of introducing some unguent or lubricating material1 such as oil1 between the surfaces in contact8 ,answer4 ,the co-efficient of friction is very much reduced thereby4 ,thus the co-efficient of friction of the cast iron plates1 if their surfaces are greased with tallow1 is #j4a2 if lubricated with lard #j4jg1 with olive oil #j4jfd1 and with lard and plumbago #j4jee1 thus showing that the amount of the friction depends very much upon the nature of the lubricant which is used1 as well as on that of the materials in contact4 ,,question #cfb4 ,what effect on the amount of friction has the manner of applying the lubricating material to the surfaces in contact8 ,answer4 ,the more perfect the lubrication the less will be the co-efficient of friction4 ,it has1 for example1 been found by experiments made with cast iron shafts turning on bearings of the same material that when the lubricating material was applied so that the surfaces were only 8unctuous10 that is slightly greasy1 the co-efficient of friction was very little less than when they were dry1 that is when there was no lubricating substance between them1 and that when they were greased 8from time to time0 the co-efficient was reduced to #j4jg and #j4jh2 but when they were continually oiled it averaged #j4je1 and sometimes fell as low as #j4jbe1 showing that with the best lubrication the friction was only one-sixth what it was when the surfaces were only 8unctuous40 ,between these two limits there is every degree of frictional resistance1 according to the condition of lubrication4 ,this shows how important it is that the oiling fixtures should be kept in the most perfect condition and the utmost care be exercised in keeping every part of a locomotive thoroughly lubricated4 ,,question #cfc4 ,what effect does the pressure per square inch of the surfaces in contact have upon the lubrication8 ,answer4 ,the tendency is1 when this pressure becomes excessive1 to press out the lubricant which is between the two surfaces1 and ordinary experience proves that the greater the weight or the force per square inch with which two bodies are pressed together1 the greater is the difficulty of keeping them perfectly lubricated4 ,thus it is easier to keep the journals of a car well lubricated when it is empty than when it is heavily loaded1 and the guide-bars of a locomotive are more liable to be cut when the engine is pulling a heavy load than with a light one4 ,,question #cfd4 ,what effect has the velocity of the surfaces in contact on the friction and lubrication8 ,answer4 ,with the surfaces in the same condition1 the friction is independent of the velocity of motion of the surfaces against each other1 but perfect lubrication becomes more difficult as the velocity increases1 so that an increase of velocity will often increase indirectly the amount of friction4 ,thus1 taking our previous illustrations1 it is more difficult to keep the journals of a car or engine well lubricated when running fast than when running slow1 and the same thing is true of the guide-bars4 ,,question #cfe4 ,what considerations should govern the proportions of frictional bearings for locomotives and other machines8 ,answer4 ,the dimensions to be given them should not be determined from a consideration solely of their resistance to rupture1#hd but they should be made so large that the pressure they must bear will be distributed over so much surface that the proportion borne by each square inch will be comparatively small1 thus making good lubrication much less difficult1 and consequently reducing the co-efficient of friction4 #hd ,morin's ,mechanics4 ,,question #cff4 ,is not the amount of energy required to overcome the friction on a journal of large diameter greater than would be required if the journal was smaller8 ,answer4 ,if the co-efficient of friction in the two cases is the same1 undoubtedly the large journal will require the greatest expenditure of energy to turn it1 because its periphery moves further than that of the small one2 but the advantage attributed to large journals is that they can be lubricated more perfectly1 because their surfaces being larger the pressure is not so great per square inch1 and thus the gain from the reduction of the co-efficient of friction is greater than the loss attributable to the increase of the diameter of the journal4 ,thus if a car journal is #c inches in diameter #e inches long1 the available surface exposed to friction is equal to that of a longitudinal section of the journal1 or #c #e #ag4hge square inches4#he ,supposing now that the journal is loaded with #e1jjj pounds1 and the average co-efficient of friction is #j4jhe4 ,in one revolution of the wheel the journal will move #j4he of a foot1 and therefore #e1jjj 4#jhe #cfa foot-pounds of work4 ,if now the journal is made1 as has been proposed1 #c #g inches1 then its effective surface will be equal to #bf square inches1 but the journal will move #j4ih of a foot in one revolution4 ,if1 however1 the lubrication is improved by the increased area of the journal so that the co-efficient of friction is reduced from #j4jhe to #j4jg1 then the energy consumed in one revolution will be equal to #e1jjj #j4g 4#ih #cdc foot-pounds1 or less than was consumed with the small journals4 ,the co-efficient of friction is assumed1 and could only be determined by experiment1 but the assumption shows how the resistance of the large journals may be less than that of the small ones4 ,of course it would be better to give the increased bearing surface by adding to the length of the journal1 but nearly all locomotives and car journals must be increased in diameter as well as in length when they are enlarged1 in order to have the requisite strength to carry the loads they must bear4 #he ,the reason for this is that the effective surface of the journal ,a1 fig4 #bji4 which resists the pressure of the bearing1 is equivalent only to the horizontal area represented by the dotted line a4 b4 just as the surface which resists the pressure inside of a boiler is equivalent to the diameter multiplied by its length1 as was explained in answer to ,question #ii4 ,,question #cfg4 ,is the law that ,,friction ,,is ,,in ,,proportion ,,to ,,the ,,pressure ,,on ,,each ,,other ,,by ,,the ,,surfaces ,,of ,,contact true under all circumstances8 ,answer4 ,no2 there is a limit to the exactness of the above law1 when the pressure becomes so intense as to crush or grind the parts of the bodies at and near their surfaces of contact4 ,at and beyond that limit the friction increases more rapidly than the pressure2#hf and the friction then becomes very irregular4 #hf ,rankine4 ,,question #cfh4 ,in what cases is the limit referred to probably reached8 ,answer4 ,probably in some locomotives the pressure of the driving-wheels on the rails is sufficient to partly crush the latter4 ,,question #cfi4 ,what effect has the nature of the materials in contact on the friction8 ,answer4 ,the amount of friction and also the lubrication is very much influenced by the nature of the bearing surface and also by the material used as a lubricant4 ,some metals1 such as brass and other alloys1 are much less liable to abrasion and seem to retain lubricants on their surfaces better than other metals1 and are therefore much used for journal and other bearings4 ,some substances1 especially oils1 are good lubricants1 while other materials of apparently similar nature are not4 ,the reason why these materials possess these properties while others are without them is not known1 and the value of any material as a lubricant1 or the degree to which another will resist friction without abrasion1 can only be tested by experiment4 ,,part ,,xix4 ,,combustion4 ,,question #cgj4 ,what is meant by combustion8 ,answer4 ,by combustion is meant the phenomenon ordinarily called burning1 as when a piece of wood or coal or a candle is burnt4 ,in reality combustion is a union of one of the 8chemical elements10 oxygen1 of which the atmosphere is composed1 with the elements which constitute the fuel4 ,,question #cga4 ,what is meant by the term 8chemical element80 ,answer4 ,the science of chemistry has demonstrated that nearly all substances by which we are surrounded are composed of certain other substances1 which latter1 as far as is now known1 are not compounds1 and are therefore called elementary substances1 or chemical elements4 ,thus the air by which we are surrounded is composed of two gases1 called nitrogen and oxygen2 water is composed of hydrogen and oxygen1 and coal chiefly of carbon and hydrogen4 ,there are now over sixty of these elementary substances known4 ,from no one of them have chemists been able to extract any material excepting the substance itself4 ,these elementary substances will combine with others so as to form what is apparently a new material1 but on weighing it it will be found that the weight of the new material is greater than the original elementary substance1 showing that something was added to it which effected the change4#hg #hg 8,the ,new ,chemistry10 by ,j4 ,p4 ,cooke1 ,jr4 ,,question #cgb4 ,to what fact is this combination or combustion of elementary substances due8 ,answer4 ,it is owing to the fact--the exact reason for which is perhaps not yet understood fully--that the atoms of the elementary substances of which fuel is composed1 that is hydrogen and carbon1 and the atoms of oxygen1 which forms part of the atmosphere by which we are surrounded1 attract each other with great energy when they are excited into activity by the application of heat4 ,,question #cgc4 ,what phenomenon always attends chemical combination of substances8 ,answer4 ,such combination always gives out heat1 whereas their separation absorbs heat4 ,it has further been proved by actual experiment that the amount of heat liberated by the chemical union of the same quantity or number of atoms of two or more substances is always the same1 and that when1 by any cause1 the atoms thus joined are separated1 exactly the same amount of heat is absorbed4#hh #hh 8,the ,new ,chemistry10 by ,j4 ,p4 ,cooke1 ,jr4 ,,question #cgd4 ,in what proportions do the elementary substances combine with each other8 ,answer4 ,it is a law of chemistry that each of the elementary substances combines with the others in certain definite proportions only4 ,these proportions vary for the different elements1 and have been determined with great accuracy by chemists4 ,thus1 eight parts by weight of oxygen will combine with nitrogen and form atmospheric air1 or the same proportion of oxygen will combine with hydrogen and form water1 or with carbon and form carbonic acid1 which is the deadly gas which accumulates at the bottom of wells4 ,now oxygen always combines with other substances in the proportion of eight parts by weight1 or by some simple multiple of eight1 that is #h #b #af parts1 or #h #c #bd parts1 etc4 ,each of the other elementary substances also has a certain fixed proportion in which it combines with others1 and this proportion1 which is usually given by weight1 is represented by a number called its chemical equivalent4 ,thus #h is the chemical equivalent of oxygen4 ,carbon combines with other elements in proportions of #f and nitrogen in proportions of #ad1 so that #f and #ad are the chemical equivalents of carbon and nitrogen4 ,now #h parts by weight of oxygen can be made to combine with #ad parts of nitrogen1 or #h #b #af parts of oxygen will combine with #ad of nitrogen1 but it is impossible to make1 say #ab parts of oxygen combine with #ad parts of nitrogen4 ,we can combine #ad #b #bh parts of nitrogen with #h parts of oxygen1 but no chemical process can make say #aj or #bj parts of nitrogen combine with #h parts of oxygen4 ,if #bj parts of nitrogen are mixed with #h parts of oxygen1 then the latter will combine with #ad parts of the former1 but #f parts of nitrogen will be left1 and chemical combination will then cease4 ,the following table will give the chemical equivalents of the principal elements which enter into the process of combustion of the fuel used in locomotives3 ,chemical equivalent by weight4 ,oxygen #h ,nitrogen #ad ,hydrogen #a ,carbon #f ,sulphur #af ,,question #cge4 ,what effect do the proportions in which elements are combined have upon the substances which are produced by the combination8 ,answer4 ,a change in the proportions in which the elements are combined usually alters the entire nature of the substance1 so far at least as it affects our senses4 ,for instance1 oxygen unites chemically with nitrogen in different proportions1 forming five distinct substances1 each essentially different from the others1 thus3 #ad parts of ,nitrogen with #h of ,oxygen forms ,nitrous ,oxide4 #ad #af ,nitric ,oxide4 #ad #bd ,hyponitrous ,acid4 #ad #cb ,nitrous ,acid4 #ad #dj ,nitric ,acid4 ,we here find the elements of the air we breathe1 by a mere change in the proportions in which they are united1 forming distinct substances1 which differ from each other as much as laughing gas 7nitrous oxide7 does from that most destructive agent nitric acid1 commonly called aqua fortis4#hi #hi ,combustion of ,coal and the ,prevention of ,smoke1 by ,c4 ,wye ,williams4 ,,question #cgf4 ,what occurs when a fresh supply of bituminous coal is thrown on a bright fire in the fire-box of a locomotive8 ,answer4 ,the fresh coal is first heated by the fire1 and if a sufficient quantity is thrown in to prevent the immediate formation of flame1#ij a volume of gas or vapor1 usually of a dark yellow or brown color1 is given off4 ,the quantity evolved will be greatest when the coal is very small4 ,this gas or vapor is commonly called smoke1 but it does not deposit soot and in reality is not true smoke4 ,if a sheet of white paper be held over the vapor as it escapes from the coal and there is no flame1 the sheet will become slowly coated with a sticky matter of brown color difficult to remove1 and having a strong tarry or sulphurous smell2 whereas if a sheet of paper is held over smoke it will quickly be covered with black soot4 ,the color and smell left on the paper in the first case are due to the tarry matter1 sulphur1 and other ingredients in the gas4 ,deprived of the coloring matters1 the vapor is a chemical mixture of #b parts of hydrogen and #f parts of carbon1 and is called carburetted hydrogen1 and is nearly the same as the colorless gas by which our houses are lighted4#ia ,a similar gas is generated at the wick of a burning candle or lamp and is consumed in the flame4 ,before the gas is expelled from the fresh coal the latter must be heated to a temperature of about #a1bjj degrees1 so that if #ajj pounds at a temperature of #ej degrees is put on the fire #bc1jjj units of heat will be absorbed to heat the coal4#ib ,nor is this all1 as has been explained in answer to ,question #ch1 when any substance is vaporized a certain amount of heat apparently disappears1 which has been called the heat of evaporation or of gasification4 ,average bituminous coal contains about #hj per cent4 of carbon1 #e per cent4 of hydrogen and #ae per cent4 of other substances usually regarded as impurities4 ,when the coal is heated up to about #a1bjj degrees1 the #e per cent4 of hydrogen unites with three times its weight of carbon1 and thus #bj per cent4 of the coal is converted into the gas described4 ,in this process a large amount of heat is absorbed or becomes latent1 as it does when water or any other substance is converted into vapor4 ,it will therefore be seen that the first effect of putting fresh coal on the fire is to cool the fire4 ,this fact has an important bearing on the question of combustion and will be referred to hereafter4 #ij ,usually if more than two or three shovels full are thrown in there will be no immediate formation of flame4 #ia ,a ,treatise on ,steam ,boilers1 by ,robert ,wilson4 #ib ,the quantity of heat required to heat coal is only about one-fifth that needed to heat the same weight of water to the same temperature4 ,,question #cgg4 ,how can the process of the combustion of the gas generated from the coal be best explained8 ,answer4 ,as this gas is substantially the same as ordinary illuminating gas1 the manner in which it burns can perhaps be made clearer by examining the combustion of an ordinary gas-light4 ,as stated before1 combustion is a chemical union of the oxygen which forms one of the elements of the air with the hydrogen and carbon of the fuel1 which1 in this case1 form gas4 ,it should be clearly kept in mind that combustion is the result of this union1 and that the oxygen is as essential to combustion as coal or gas1 and in fact is the fuel of combustion just as much as coal or gas is4 ,if we were to conduct a pipe from the external air into a vessel filled with coal gas we could light the air and it would burn in the gas as the gas burns in the air4 ,it will be noticed1 however1 that before either the gas or the air will burn1 they must be lighted4 ,air and gas1 even if mixed together in the same vessel1 will not burn unless they are lighted4 ,this can be done by the flame of any burning material1 or with a piece of metal heated to a very high temperature1 or by an electric spark4 ,in other words it may be said that the atoms of the two gases must be excited into activity by the application of heat1 that is1 what is called an igniting temperature must be communicated to them before chemical combination will begin4 ,the chief feature which distinguishes combustion from other chemical union is the circumstance that the heat generated during the combination is sufficient to maintain an igniting temperature1 and the necessity of doing so in order to continue the process is of very great importance in the combustion of coal in locomotive boilers1 as will be shown hereafter4 ,,question #cgh4 ,how does an ordinary gas-light burn after it is lighted8 ,answer4 ,under ordinary conditions the hydrogen1 which is the most combustible of the two elements of which coal gas is formed1 is the first to burn4 ,this part of the combustion forms the lower bluish part of the flame4 ,the combustion of the hydrogen thus separates it from the carbon1 which is then set free2 and as carbon is never found in a gaseous condition when uncombined with other substances1 it at once assumes the form of fine soot when the hydrogen is burned away from it4 ,this fine soot1 or pulverized carbon1 is1 however1 intensely heated by the combustion of the hydrogen4 ,now carbon when heated to an igniting temperature will1 if brought into contact with a sufficient quantity of oxygen1 combine with it or be burned4 ,each particle of carbon thus becomes a glowing centre of radiation1 throwing out its luminous rays in every direction4 ,the sparks last1 however1 but an instant1 for the next moment they are consumed by the oxygen which is aroused to full activity by the heat1 and only a transparent gas rises from the flame4 ,but the same process continues2 other particles succeed1 which become heated and ignited in their turn1 and it is to this combustion of the solid particles of carbon that the light which is given out by a gas-burner or candle is due4#ic #ic 8,the ,new ,chemistry0 by ,j4 ,p4 ,cooke1 ,jr4 ,illustration3 ,fig4 #baj4 ,fig4 #baa4 ,,question #cgi4 ,why does a gas-burner1 candle or other flame sometimes smoke8 ,answer4 ,because the supply of oxygen is then insufficient to consume the particles of solid carbon which are set free and which then assume the form of soot4 ,this can be illustrated if we cut a hole in a card1 d d1 fig4 #baj1 so as to fit over an ordinary gas-burner1 b4 ,if we then light the gas and place a glass chimney1 a a1 over the burner and let it rest on the card1 it will be found that the flame will at once begin to smoke1 because very little air can then come in contact with the flame1 and therefore when the fine particles of carbon are set free by the combustion of the hydrogen1 instead of being burned as they would be if the air with its supply of oxygen were not excluded from the flame by the chimney1 they escape unconsumed in the form of fine black powder or soot4 ,if we raise the chimney up from the card1 as shown in fig4 #baa1 so as to leave enough space between them at the bottom of the chimney to permit air to enter so as to supply the flame with oxygen1 the smoke will instantly cease1 as the particles of carbon are then consumed4 ,the same principle is illustrated in an ordinary kerosene lamp4 ,it is well known that without a chimney the flames of nearly all such lamps smoke intolerably1 whereas with a glass chimney and the peculiarly formed deflector which surrounds the wick the light burns without smoke unless the wick is turned up high4 ,the effect of the chimney is to produce a draft1 which is thrown against the flame by the deflector1 and thus a sufficient supply of oxygen is furnished to consume all the particles of carbon1 whereas without the draft produced by the chimney the supply of oxygen is insufficient to ignite all the carbon1 which then escapes in the form of smoke or soot4 ,illustration3 ,fig4 #bab4 ,fig4 #bac4 ,it must not1 however1 be hastily assumed that if the flame does not give out a bright light1 therefore the combustion is not complete4 ,as has already been stated1 the light of the gas flame is due to the presence of burning particles of solid carbon1 which is set free by the combustion of the hydrogen with which it is combined4 ,after it is separated from the hydrogen it immediately assumes a solid form4 ,if the coal gas is mixed with a sufficient quantity of air before it is burned1 the oxygen in the latter will be in such intimate contact with the former that the difference of affinity of oxygen for the carbon and hydrogen does not come into play1 and as there is enough oxygen for all1 the carbon is burnt before it is set free1 and as there are then no solid particles in the flame1 there is no light4 ,this is illustrated by a 8,bunsen burner10 fig4 #bab1 which is much used in chemical laboratories4 ,it consists of a small tube or burner1 a1 which is placed inside of another larger tube b4 ,the latter has holes1 c1 c1 a little below the top of the small tube4 ,the current of gas escaping from the small tube produces what is called an induced current of air in the large tube4 ,this air enters through the holes c1 c1 and is mixed with the gas in the tube b1 and the mixture is burned at d4 ,the flame from such a burner gives hardly any light1 but the heat is intense1 as is shown if a metal wire is held in it for a few seconds1 as it will very soon glow with heat4 ,,question #chj4 ,what important difference is there in the structure of the flame of a ,bunsen burner and that of an ordinary gas-burner or candle8 ,answer4 ,the gas which escapes from the mouth d of the pipe b1 fig4 #bab1 is mixed with air1 and therefore contains within itself the elements which only need to combine to produce combustion2 whereas with an ordinary gas-burner or candle the air comes in contact with the flame only from the outside1 or on its surface4 ,this is shown better perhaps in the flame of an ordinary candle4 ,the heat of such a flame distils a gas from the melted tallow1 which is similar in nature to that which escapes from coal at a high temperature4 ,now by observing the candle very closely it will be seen that at the bottom close to the wick there is very little combustion1 as the gas there first escapes from the wick and is not heated to a sufficiently high temperature to burn freely4 ,a little above the lowermost part the flame is of a pale bluish color1 which is due to the combustion of the hydrogen4 ,above that1 where the carbon is set free1 its particles glow with heat imparted by the burning hydrogen and are then consumed by uniting with the oxygen of the air4 ,the combustion occurs only at the surface of the flame1 the inside being a mass of combustible gas which cannot burn until it in turn comes in contact with the oxygen of the air4 ,this can be proved by inserting one end of a small tube1 fig4 #bac 7a pipe stem will do71 which is open at both ends1 into the flame4 ,the combustible gas will then escape at the other end and can easily be lighted with a match4 ,it will be found that the flame from the ,bunsen burner is much more intense than that of an ordinary candle or gas-burner4 ,the reason of this is that combustion1 as already stated1 takes place through the whole mass of its flame1 whereas an ordinary flame burns only at its surface4 ,common gas-jets are therefore arranged so that the flames will be flat1 thus exposing as much surface to the air as possible1 and1 as explained in answer to ,question #cbi1 in describing the lamps for head-lights1 their burners are usually made with a circular wick1 through the centre of which a current of air circulates4 ,this arrangement exposes a larger surface of the flame to the air1 and also with the aid of a chimney furnishes an abundant supply for combustion4 ,in stationary boilers with long flues of a large sectional area the flame will often extend for thirty feet1 showing that while combustion is going on only at the surface of the flame1 it takes a long time to complete the process4 ,the same thing is shown if a gas-burner is made with a single round hole4 ,the flame will then be very long and liable to smoke at the top4 ,,question #cha4 ,from the preceding considerations what may we infer to be necessary in order to consume coal gas perfectly8 ,answer4 ,in the first place1 that there must exist a certain degree of what chemists call 8molecular activity10 which is produced by heat1 or what we have called the igniting temperature4 ,the necessity of this is sufficiently obvious with ordinary gas-burners1 as they must always be lighted before they will burn4 ,now imagine that it was required to burn gas which was issuing from a hundred jets1 of every variety of size1 in a violent wind storm1 or gusts of wind4 ,obviously it would be necessary to keep a lighted torch all the time to relight those which would be blown out4 ,the gas in a locomotive fire-box is in reality burnt in a storm of wind more violent than any natural one4 ,it is therefore necessary to be constantly ready to relight the streams of gas which the faintest breath would extinguish1 or those of larger volume which have absorbed a great deal of heat and thus reduced the temperature at the time and place of their birth1 when they assumed the gaseous form1 as was explained in answer to ,question #cgf4 ,to relight them with certainty it is necessary to keep a constant temperature in the fire-box high enough to ignite the gas which escapes or is distilled from the coal4 ,second4 ,that the chemical change in combustion consists simply in the union of the elements burned with the oxygen of the air2 and therefore1 to burn the gas perfectly1 without smoke or waste1 enough air must be furnished to supply all the oxygen which will combine with the fuel4 ,third4 ,that the air must be mixed with the gas1 otherwise combustion will occur only at the surface of the flame1 and will therefore be so slow that much of the gas will escape unconsumed4 ,it must be clearly kept in mind that no one or two of these requirements alone1 without the third1 will burn coal perfectly4 ,what is needed is all three in combination4 ,a very common error is to suppose that passing smoke over a hot fire1 or in other words1 maintaining an igniting temperature1 will alone effect perfect combustion2 or that if a sufficient supply of air is admitted1 without an igniting temperature in the fire-box1 the fuel will be burnt completely4 ,neither of them will accomplish the object alone1 and the gas and air must at the same time be thoroughly mixed with the burning gas in the fire-box4 ,,question #chb4 ,what substances are produced by the combustion of coal gas8 ,answer4 ,the hydrogen of coal gas unites during combustion with oxygen in the proportion1 as indicated by their chemical equivalents1 of #a part by weight of hydrogen with #h parts of oxygen1 the product of which is water4 ,of course at the high temperature at which the gases combine or burn the water is produced in the form of steam4 ,that water or steam is one of the products of combustion is shown every cold evening1 when the insides of shop show-windows are covered with moisture1 which is due to the steam that is given off by the burning gas-lights or lamps inside1 and is then condensed against the cold glass4 ,carbon combines with oxygen in two proportions3 first1 #f parts of the former will unite with #h of the latter1 forming what is called carbonic oxide2 or #f parts of carbon will combine with #af parts of oxygen1 forming carbonic acid gas or carbonic dioxide1 as it is called in some of the new books on chemistry4 ,it is probable that the former compound1 that is carbonic oxide1 is never or very rarely formed in the flame of coal gas2 but1 as will be seen hereafter1 is a very common and wasteful product of the combustion of the solid portion of the coal which is left after the gas is expelled from it4 ,when there is not enough oxygen for the perfect combustion of the carbon in the flame1 it smokes1 and the carbon escapes in the form of soot4 ,this1 as will be shown1 may in a locomotive fire-box help to form carbonic oxide after it leaves the flame4 ,,question #chc4 ,what remains in the coal after all the gas is expelled by heat8 ,answer4 ,what remains is ordinarily called coke1 which1 with the exception of some incombustible substances1 such as sand1 ashes and cinders1 which the coal contains1 is nearly pure carbon4 ,,question #chd4 ,what is the chemical process of the combustion of coke8 ,answer4 ,the solid carbon of the coke when raised to an igniting temperature2 or1 in other words1 on being lighted1 unites with the oxygen in one of the two proportions already given2 that is1 if the supply of oxygen is sufficient1 #f parts of the carbon of the coke unite with #af parts of oxygen1 forming carbonic acid gas1 or carbonic dioxide4 ,if1 however1 the layer of fuel on the grates is thick1 or the supply of air is comparatively small1 there will not be enough oxygen to supply #af parts of the latter to each #f parts of the carbon1 so that when that occurs1 instead of combining in that proportion1 and thus forming carbonic dioxide1 #h parts of oxygen will unite with #f parts of carbon and form carbonic oxide4 ,now it should be carefully kept in mind that the heat of combustion is due to the union1 or1 as it is sometimes expressed1 it is the clashing together of the molecules of the two elements which unite4 ,if1 therefore1 only half the quantity of oxygen unites with #f parts of carbon1 evidently there will be less heat evolved than there would be if twice that amount of oxygen combined with the carbon4 ,from carefully made experiments it was found that the total heat of the combustion of one pound of carbon when converted into carbonic oxide was #d1djj units1 whereas when it was converted into carbonic dioxide #ad1ejj units were given out4 ,it will thus be seen that it is extremely wasteful to burn coal without a sufficient supply of air to produce carbonic dioxide4 ,the danger of waste from this cause is also increased by the fact that carbonic oxide is colorless and odorless1 and therefore its production is not apparent1 especially as most persons have the impression that when there is no smoke from a fire combustion is then complete4 ,it burns with a blue or yellowish flame when air is admitted into the fire-box1 and its presence can often be detected by these phenomena when the furnace door is opened4 ,,question #che4 ,how can the requisite quantity of air be supplied to the fire in a locomotive fire-box8 ,answer4 ,it is done in two ways3 one is to keep but little coal on the grates1 or in the phraseology of firemen1 to 8carry a light fire40 ,the other method is to admit fresh air above the fire4 ,if the latter plan is adopted when the supply of air through the grates is insufficient for perfect combustion1 the carbonic oxide will unite with the oxygen of the air above the fire1 and thus a second combustion will take place1 the product of which will be carbonic dioxide4 ,it must be kept in mind1 however1 that not only must there be enough air supplied to the fire to consume the coke1 but the gases which are distilled from the coal must also be supplied with oxygen in order to effect their perfect combustion4 ,even if enough air is admitted to consume the coke perfectly1 if the carbonic dioxide thus formed is mixed with large quantities of smoke above the fire1 the solid carbon or soot of the smoke may then combine with the dioxide and thus form carbonic oxide1 if there is not enough fresh air present to furnish the requisite oxygen for the carbon in the smoke4 ,a very common error is to suppose that smoke can be burned by passing it over or through a very hot fire4 ,the smoke may thus be made invisible1 it is true1 but it does not therefore follow that it is perfectly consumed4 ,,question #chf4 ,is it possible to admit too much air into the fire-box of a locomotive8 ,answer4 ,yes2 probably all the air that is admitted which is not necessary for combustion1 or1 in other words1 the oxygen of which does not combine with the fuel1 instead of increasing diminishes the amount of water converted into steam4 ,it does this in two ways2 first1 by reducing the temperature of the gases in contact with the heating surfaces1 and second1 by increasing the volume or quantity of the gases which must pass through the tubes4 ,heat is transmitted through the heating surface of a boiler in proportion to the difference of the temperature of the products of combustion on one side and the water on the other4#id ,thus1 if the temperature of the water on one side is #bej degrees1 and the hot gases on the other is #ejj1 there will be only half as much heat transmitted to the water in a given time as there would be if the gases had a temperature of #gej degrees4 ,if the volume of gases is doubled by the admission of too much air1 then obviously in order to pass through the tubes they must move at double the velocity1 so that not only is their temperature diminished1 but the time they are in contact with the heating surface is diminished in like proportion4 ,this is shown by the effect of opening the furnace door1 or of allowing the fire to burn away so that portions of the grate are left uncovered4 ,the volume of cold air which will in either of these cases enter the fire-box will be so great that the pressure of the steam in the boiler will begin to fall at once4 #id ,this law is perhaps not absolutely correct1 but is near enough for our present illustration4 ,,question #chg4 ,what determines the amount of air which must be admitted to the fire-box of a locomotive to effect perfect combustion8 ,answer4 ,this depends chiefly upon the rate of combustion1 that is1 the number of pounds of coal consumed per hour on each square foot of grate surface4 ,of course if #ajj pounds is burnt it will require twice the supply of air that would be needed if only #ej pounds were burnt4 ,,question #chh4 ,how should the air be admitted so as to burn the coal perfectly8 ,answer4 ,in burning bituminous coal it has been shown that there are two distinct bodies to be dealt with1 the one coke1 a solid1 the other coal gas1 which is of course a gaseous body4 ,the combustion of each of these is necessarily a distinct process4 ,if the requisite quantity of air is supplied to the burning coke1 or solid portion of the coal1 it will1 as has been shown1 be converted into carbonic dioxide1 and thus be perfectly consumed4 ,if the supply of air is insufficient1 the product of the combustion will be carbonic oxide1 which is very wasteful4 ,if1 for example1 there is a thick layer of coke on the grate1 the air will enter and unite with the lower layer of coal and form carbonic dioxide1 but as it rises there will not be enough air to supply oxygen to the carbon1 and another equivalent of the latter will therefore combine with the carbonic dioxide and form carbonic oxide4 ,it is evident1 though1 that the thinner the fire1 the easier it is for air to pass through it1 and consequently the greater will be the quantity which will enter the fire-box4 ,nothing would seem easier then than to regulate the thickness of the fire on the grates so that just the needed amount of air would pass through it4 ,if coke alone was to be burned1 undoubtedly very perfect combustion would be 7and has been7 effected in this way1 but if a charge of fresh coal1 say #ajj pounds1 is thrown on the fire1 the coal gas is very soon generated and escapes into the fire-box4 ,this gas needs an additional amount of air for its combustion4 ,it would seem that this could be supplied by reducing the thickness of the fire still further1 so that more air would pass through it than was needed for the combustion of the coke alone4 ,if this was done then too much air would pass through the coke after the gases had all escaped from the fresh coal and were burned4 ,besides1 the passage of the air would be the most restricted after the fresh charge had been put on the fire1 just at the time when the most is needed4 ,this difficulty might be overcome if a constant supply of fresh coal just equal to that consumed were kept on the fire all the time1 and the thickness of fuel on the grates was then regulated so as to admit just air enough for the combustion of the coke and also that of the gases1 the production of which would then be uniform4 ,an approximation to this method of feeding the fire is1 in fact1 what is aimed at on most locomotives1 and probably the best practical results are produced by that method4 ,two difficulties are1 however1 encountered in this method4 ,in the first place it is impossible to feed a fire continuously with a shovel4 ,there will be intervals between the charges which are thrown in1 so that the supply is not uniform1 even if the charges do not consist of more than a portion of a shovel-full at a time2 and if the fire was fed in this way as uniformly as possible it would then be necessary to open the furnace door every time fresh coal was put on the fire1 and so much cold air would thus be admitted that more would be lost by lowering the temperature of the boiler than would be gained by the improved combustion4 ,another difficulty also is encountered in this method of burning coal in locomotives4 ,in order to admit enough air through the fire it is necessary to keep the latter so thin on the grates that the violent draft produced by the blast lifts the coal from the grate-bars and carries the lighter particles through the flues unconsumed4 ,it is thus extremely difficult to keep the grate uniformly covered with coal1 and if it is not1 the air will enter in irregular and rapid streams or masses through the uncovered parts1 and at the very time when it should be there most restricted4 ,such a state of things at once bids defiance to all regulation or control1 so that it is found almost uniformly that firemen of locomotives keep enough coal on the grates to avoid the danger of 8losing their fire10 as they express it2 that is1 having all the burning coal drawn through the tubes by the blast4 ,now1 on the control of the supply of air depends all that human skill can do in effecting perfect combustion and economy2 and unless the supply of fuel and the quantity on the bars can be regulated1 it will be impossible to control the admission of the air4#ie #ie ,the ,combustion of ,coal1 by ,c4 ,wye ,williams4 ,another method of feeding locomotive boilers is to pile up the coal in the back part in a thick layer and slope it downward towards the front1 so that there is a comparatively thin fire in front4 ,the mass piled up at the door becomes converted into coke1 and the production of gas from the coal is more gradual and uniform than it is when only a small quantity is thrown in at a time1 and therefore a more uniform supply of air is needed for its combustion4 ,but it is apparent that very little air can pass through the thick heap of coal at the back part of the fire-box1 and that therefore all1 or nearly all the air which enters it must come in through a comparatively small portion of the grate4 ,it will of course be difficult to admit the requisite quantity1 for the reasons already stated4 ,it is consequently apparent that it is practically impossible to admit enough air through the grates to effect a constantly perfect combustion of bituminous coal4 ,it is1 therefore1 necessary to admit a portion of the air above the fire4 ,in doing this1 however1 in order to effect perfect combustion the air thus admitted must be thoroughly mixed with the gases1 and in order to be able to enter into chemical combination1 or in other words1 to burn1 the gases must combine with the air at an igniting temperature4 ,if too much air is admitted1 it will reduce the temperature in the fire-box so much that the gases will not ignite2 or1 if it is admitted in strong currents1 the air and the gases will flow side by side like the currents of two streams of water1 the one muddy and the other clear1 which1 as is well known1 mingle very slowly4 ,besides1 if a hot stream of gas encounters a strong stream of cold air and comes in contact with it only at its surface1 the latter will be cooled down below the igniting temperature2 whereas if the two had been intimately mixed in the right proportion1 the whole mixture would have been hot enough to burn4 ,it is therefore of the utmost importance that the air which is admitted above the fire should enter the fire-box in many small jets4 ,none of the openings for its admission should exceed inch in diameter4 ,with the violent draft in a locomotive fire-box there is an extremely brief period of time for chemical combination to take place after the gases are expelled from the coal and before they are hurried into the tubes4 ,as the chemical action between the gases and the oxygen can only take place when the two are in intimate contact1 too much pains cannot be taken to distribute the currents of admitted air and thus mix them with the combustible gases4 ,in many cases means are adopted to delay the air and the gases in the fire-box so as to give them time for chemical combination or combustion before entering the tubes4 ,,question #chi4 ,does any combustion take place after the gases enter the tubes8 ,answer4 ,very little2 as the flames are extinguished soon after they enter4 ,,question #cij4 ,why are the flames extinguished in the tubes8 ,answer4 ,they are then in contact with large quantities of incombustible gas and beyond the reach of a supply of air2 besides1 the temperature of the tubes which are surrounded with water is so low that the flame is soon cooled down below an igniting temperature4 ,,question #cia4 ,what temperature is necessary to ignite coal gas or produce flame8 ,answer4 ,a temperature considerably hotter than red-hot iron is needed1 as can easily be shown by the fact that a gas-light can not be ignited with a red-hot poker4 ,,question #cib4 ,are there any parts of the fire-box where the temperature is probably below the igniting point8 ,answer4 ,yes2 along the sides and ends near the plates1 which are covered with water on the opposite side4 ,at these points the coal is usually 8dead0 or incandescent1 as it remains at too low a temperature to burn4 ,for this reason1 in some cases a space of from #h to #ab inches on each side and still more at the ends of the grates1 is made of solid plates1 without any openings1 and therefore called 8dead-grates10 so that no cold air can enter at those points4 ,these plates are made sloping downwards from the sides towards the centre of the fire-box1 so that the coal which falls on them and is thus coked1 can easily be raked towards the middle of the fire4 ,this arrangement of dead plates often improves the combustion and results in greater economy of fuel4 ,the reduction of the area of the openings between the grate-bars can usually be compensated by making the bars narrower or the spaces between them wider4 ,,question #cic4 ,what should be the condition of the coal when it is put on the fire8 ,answer4 ,it is true of the coal as well as of the gases that the chemical action between it and the oxygen can only take place when the two are in intimate contact1 and therefore the rapidity and completeness of combustion and intensity of heat will be increased by increasing the number of points of contact1 or by reducing the size of the fuel4 ,the coal should therefore be broken up1 but not so small as to fall between the grate-bars or be carried out of the fire-box by the blast4 ,,question #cid4 ,what amount of air must be admitted to the fire to effect perfect combustion8 ,answer4 ,it was stated that average bituminous coal contains about #hj per cent4 carbon1 #e per cent4 of hydrogen and #ae per cent4 of other substances4 ,as a large proportion of the latter are incombustible1 we will confine ourselves for the present to the consideration of the combustion of the hydrogen and carbon alone4 ,the hydrogen1 as has been explained1 unites with oxygen in the proportion by weight of #a part of the former to #h parts of the latter1 and the product of this union is water1 or steam4 ,as #cf parts of air contain only #h of oxygen1 ,,in ,,order ,,to ,,burn ,,the ,,hydrogen ,,it ,,must ,,be ,,supplied ,,with #cf ,,times ,,its ,,weight ,,of ,,air4 ,in order to burn the carbon perfectly it must1 as has been explained1 be converted into carbonic dioxide1 which consists of #f parts of carbon and #af of oxygen2 and as air consists of #bh parts of nitrogen to every #h of oxygen1 we must furnish #gb parts of air to every #f of carbon1 or1 in other words1 ,,carbon ,,needs #ab ,,times ,,its ,,weight ,,of ,,air ,,for ,,its ,,perfect ,,combustion4 ,every pound of average bituminous coal therefore requires #a4h lbs4 of air to burn its hydrogen1 and #i4f lbs4 for the carbon1 or #aa4d for both4 ,as a portion of the other substances of which coal is composed1 besides the oxygen and hydrogen1 which others have been classed as impurities1 are combustible1 there will be no material error if we estimate the amount of air required for the combustion of bituminous coal at #ab ,,pounds ,,per ,,pound ,,of ,,fuel4 ,as each cubic foot of air weighs #j4jhjgb lb41 #ab pounds will be equal to #ab ------- #adh4f cubic feet of air1 #j4jhjgb or for the sake of even figures and a quantity which can easily be remembered1 we will say #aej ,,cubic ,,feet ,,of ,,air ,,are ,,needed ,,for ,,the ,,combustion ,,of ,,each ,,pound ,,of ,,coal4 ,this is the theoretical quantity of air which is needed for combustion4 ,now1 unfortunately1 the process of combustion in the fire-boxes of locomotives is one in which any very exact combination of the substances which unite is not possible with the appliances which are now employed4 ,if1 therefore1 we admitted the exact amount of air given above1 while some portions of the fire where combustion was not very active might have more air than is needed1 other portions would have too little2 and if the air is not very thoroughly mixed1 the flame and burning coal may be surrounded with the products of combustion1 which would exclude the air and thus reduce its effect upon the fire4 ,for this reason1 besides the air required to furnish the oxygen necessary for the complete combustion of the fuel1 it is also necessary to furnish an additional quantity of air for the dilution of the gaseous products of combustion1 which would otherwise prevent the free access of air to the fuel4 ,the more minute the division and the greater the velocity with which the air rushes among the fuel1 the smaller is the additional quantity of air required for dilution4 ,in locomotive boilers1 although this quantity has not been exactly ascertained1 there is reason to believe that it may on an average be estimated at about one-half of the air required for combustion4#if ,we would therefore have as the quantity of air needed for combustion #aej #aej --- #bbe cubic feet4 #b ,this estimate is roughly made1 but it is the nearest approximation at present attainable4 ,it is probable that the supply of air required for dilution varies considerably in different arrangements of the fire-box and for different kinds of fuel1 and it is possible that by admitting the air for combustion in small enough jets1 and deflecting the currents of smoke and gases so as to cause them to mingle with the air1 the quantity required for dilution might be reduced below that indicated by the above calculation4 ,undoubtedly all the air which is admitted into the fire-box which does not combine with the chemical elements of the fuel lessens the amount of steam generated in the boiler1 both with reference to time1 that is to say per minute1 and to fuel1 that is per pound of coal consumed4 ,but with the present locomotive boiler it is simply a choice of two evils4 ,if no more air is admitted than theory indicates to be needed for combustion1 then1 owing to the imperfect means which are usually employed to cause the air and fuel to combine1 a portion of the latter will escape unconsumed2 and if more air is admitted1 the temperature of the products of combustion is lowered and their volume increased1 the evils of which have already been pointed out4 ,it therefore becomes a matter in which we are obliged to consult experience and determine by experiment what amount of air it is necessary to admit to the fuel to produce the most economical results4 #if ,rankine4 ,,question #cie4 ,what proportion of the air should be admitted through the grate1 and how much above the fire8 ,answer4 ,this1 too1 is a question which can probably be answered best by consulting experience4 ,the relative quantity of air required above and below the fire depends very much on the nature of the fuel4 ,coal which 8runs together0 or cakes very much or has a great deal of clinker in it1 doubtless1 will need more air above the fire than other coal which is said to be 8dryer10 for the reason that it will be found impossible to admit so much air through the caking coal in the grate as through the other kind4 ,an idea of the relative quantity which should be admitted above and below the fire may be found if we know how much air is needed to burn the solid carbon or coke which is left after the gas is expelled from it1 and how much for the gas itself4 ,the gas which is expelled from a pound of coal consists of about #j4je lb4 of hydrogen and #j4ae lb4 of carbon4 ,now1 it has been shown that hydrogen requires #cf times its weight of air to burn it perfectly1 so that #j4je lb4 would need #j4je #cf #a4h lbs42 and carbon requires #ab times its weight of air1 so that for #j4ae lb4 of carbon #j4ae #ab #a4h lbs4 is needed1 so that for both #c4f lbs4 of air is required for perfect combustion4 ,as has been shown1 #ab lbs4 is needed to consume the whole of the fuel1 so that #cj per cent4 of the whole supply is required for the combustion of the gas alone4 ,if this is diluted in the same proportion as that required for the combustion of the carbon1 and it probably should be even more so1 we would have #cj per cent4 of #bbe #fg4e cubic feet of air required for the combustion of the gas4 ,it is certain1 however1 that the solid coke on the grates is not perfectly consumed1 or1 in other words1 converted into carbonic dioxide1 especially when the layer of it on the grates is very thick4 ,when this is the case the air coming in contact with the lower layer of coke forms carbonic dioxide1 but as it rises through the burning coke another equivalent of carbon unites with the carbonic dioxide1 and thus forms carbonic oxide4 ,if1 now1 enough air is admitted above the fire1 this carbonic oxide will combine with it1 and1 as has been explained before1 a second combustion will take place if there is time and opportunity for combination before the gases enter the flues4 ,it is therefore probable that more than #cj per cent4 of the whole supply of air should be admitted above the fire4 ,it is at any rate best to provide the means for admitting more1 and also appliances for regulating the supply1 so that it can be governed as experience may indicate to be best4 ,,question #cif4 ,is it not possible by enlarging the grate to admit enough air to the fire to produce perfect combustion8 ,answer4 ,yes2 when no air is admitted above the fire1 large grates are found to produce the best combustion4 ,but while it is true that the same amount of heat will be produced by the union of each equivalent of oxygen and fuel1 yet if we can force more air and fuel to unite in the same place1 a higher temperature is produced in that place1 just as a fire in a blacksmith's forge is hotter because of the forced blast than that in an ordinary stove1 or a smelting furnace than a parlor grate4 ,if1 then1 we can concentrate the draft in the fire of a locomotive1 we secure a greater intensity of combustion2 and when the air is urged against the solid carbon with considerable force1 it comes in contact with every point of its surface1 and therefore less dilution of the air is needed1 and consequently the products of combustion have a higher temperature2 and1 as has been explained1 a larger proportion of the heat is then transferred to the water than if the temperature is lower and the volume greater4 ,intensity of combustion also has the effect of maintaining an igniting temperature2 whereas1 if the same amount of fuel is burned slowly1 its heat may not be high enough to ignite the gases as they are produced4 ,it is desirable1 however1 to have all the space that is possible in the fire-box1 so as to give room for the mixing of the gases2 but with a large fire-box and large grate a decided improvement and economy will often result by diminishing the effective area of the grate by covering a part of it with dead plates1 but at the same time making provision for the admission of air above the fire4 ,,question #cig4 ,what is meant by the 8,total ,heat of ,combustion80 ,answer4 ,it is the number of units of heat given out by the combustion of a given quantity 7usually a pound7 of fuel4 ,,question #cih4 ,how is this determined8 ,answer4 ,the heat given out by the combustion of one pound of the chemical elements of which coal is composed has been determined by experiment1 and from such data1 knowing the substances of which fuel is composed1 we can determine the amount of heat which would be developed if they were each perfectly consumed4 ,thus the total heat of combustion of one pound of hydrogen is #fb1jcb units1 and of the same quantity of carbon #ad1ejj units4#ig ,therefore1 if a pound of coal contains #e per cent4 of hydrogen1 the heat given out by the combustion of that element will be #fb1jcb #j4je #c1aja4fj units1 and if it has #hj per cent4 of carbon1 the combustion of the latter would develop #ad1ejj #j4hj #aa1fjj units1 so that the total heat of the combustion of these two elements would be #c1aja4f #aa1fjj #ad1gja4f units4 ,it was shown in answer to ,question #dj that it required #a1bac4d units of heat to convert water at zero to steam of #ajj pounds pressure4 ,as steam is usually generated from water at a temperature of about #fj degrees1 the total heat required to convert it into steam of #ajj pounds pressure would be #a1bac4d - #fj #a1aec4d units4 ,a pound of average bituminous coal1 therefore1 contains heat enough to convert #ab lbs4 of water into steam of #ajj lbs4 absolute pressure4 ,ordinarily only about half that amount of water is evaporated in locomotive boilers per pound of fuel4 #ig ,the experiments which have been made to determine these amounts do not agree exactly1 but those given are thought to be the most trustworthy4 ,,question #cii4 ,what are the chief causes of this waste of heat8 ,answer4 ,it is due1 first1 to the waste of unburnt fuel in the solid state4 ,this occurs when fuel which is very fine falls through the grates1 or is carried through the tubes and out of the stack in the form of cinders4#ih #ih ,it should be remarked here that some and perhaps most of the cinders which are carried out of the stack are not combustible but are composed of the same materials that form clinkers on the grate4 ,second1 to the waste of unburnt fuel in the gaseous or smoky state4 ,the method of preventing this waste by a sufficient supply and proper distribution of air has been explained in the answer to preceding questions4 ,third1 to the waste or loss of heat in the hot gases which escape up the chimney or smoke stack4 ,the temperature of the fire in a locomotive fire-box in a state of active combustion is probably from #c1jjj to #d1jjj degrees4 ,this heat is in part radiated and conducted to the heating surface of the fire-box1 and it is found that more water is evaporated by this portion of the heating surface in proportion to its area than by any other in the boiler4 ,the gases when they enter the tubes transmit a portion of their heat to the surfaces with which they are first in contact4 ,the amount of heat thus transmitted1 as has been stated1 is in proportion to the difference in temperature of the gases inside the tubes and that of the water outside4 ,after passing over the part of the tube with which the gases are first in contact1 they then arrive at another portion of the tube surface with a diminished temperature1 and the rate of conduction is therefore diminished2 so that each successive equal portion of the heating surface transmits a less and less quantity of heat1 until the hot air at last leaves the heating surface and escapes up the chimney with a certain remaining excess of temperature above that of the water in the boiler1 the heat corresponding to which excess is wasted4#ii ,it is1 therefore1 desirable to extract as much heat as possible from the gases before they escape from the tubes4 ,now it will be impossible to heat the water outside of the tubes hotter than the gases inside4 ,when the temperature of the water is equal to that of the gases1 no more heat will be transmitted from one to the other4 ,if the temperature of the water is #cej degrees1 that of the gases in the tubes will never be any lower1 but will escape into the smoke-box with not less than that amount of heat4 ,if1 however1 the cold water is introduced at the front end of the tubes1 so that the surface with which the gases are last in contact has a temperature considerably lower than #cej1 then an additional amount of heat will be transmitted before they escape4 ,it is1 therefore1 important that the cold feed-water should be admitted near the front end of the boiler1 so that the products of combustion will be in contact with the coldest part of the heating surface last1 and thus give out as much of their heat as possible before they escape4 ,as a matter of fact1 the gases escape at a much higher temperature4 ,experiments made by the writer showed that the temperature in the smoke-box of a locomotive when first starting was #bgj degrees1 and when working at its maximum capacity on a steep grade and with a heavy train it was as high as #fge degrees4 ,the average temperature while running was1 in three trials on different parts of the road1 as follows3 ,average steam pressure1 #ih4h lbs42 average temperature1 #dii4h lbs4 ,average steam pressure1 #ajf lbs42 average temperature1 #ece4a lbs4 ,average steam pressure1 #aab4b lbs42 average temperature1 #eed lbs4 #ii ,rankine4 ,in making these experiments a record was made of the indications of a pyrometer and of the steam gauge once every minute while the engine was running4 ,the distance run was #ai miles for the first experiment1 #ac for the second and #f for the third1 with #cj loaded freight cars in the train4 ,the last experiment was made while the engine was working on a heavy grade and very nearly up to its maximum capacity4 ,it will thus be seen that a great deal of heat is wasted by escaping up the chimney4 ,fourth1 by external radiation from the boiler4 ,this occurs chiefly from the fact that it is not sufficiently well protected or covered with non-conducting material4 ,the practice1 or rather the neglect1 of not covering the outside of the fire-box with lagging doubtless causes a very considerable loss of heat by radiation and convection from the hot boiler plates4 ,,question #djj4 ,what is the ordinary form of fire-box employed for burning bituminous coal8 ,answer4 ,it is that represented in plate ,,ii and figs4 #da and #dd1 and is simply a rectangular box1 and for that reason it is called a plain fire-box4 ,sometimes provision is made for admitting air into such fire-boxes through hollow or rather tubular stay-bolts1 which are put into the sides and front4 ,in most cases1 too1 the fire-box door has perforations for admitting air4 ,illustration3 ,fig4 #bad4 ,scale in4 #a foot4 ,,question #dja4 ,what other appliances are used for burning bituminous coal8 ,answer4 ,the most common appliance which is added to the plain fire-box is what is called a fire-brick arch4 ,this is shown in fig4 #bad4 ,b ,c is the arch which1 as its name implies1 is formed of fire-brick and extends backward and upward from a point in the tube-sheet below the tubes4 ,in order to be self-supporting it is built in the form of an arch1 the two sides of the fire-box acting as abutments for its support4 ,the engraving represents with sufficient clearness the direction of the flames and smoke4 ,these must take a more circuitous 8run10 as it is called1 after leaving the fire1 in order to reach the tubes4 ,time is thus given for the gases to combine and combustion to take place4 ,the fire-brick becomes heated1 and thus to some extent prevents the gases from being cooled down below an igniting temperature by contact with the cold surface of the fire-box before combustion is complete4 ,the fire-brick1 however1 soon burns out1 and must be replaced1 but owing to its cheapness and the ease with which it can be removed1 this does not make a serious objection to its use4 ,air is nearly always admitted above the fire when the brick arch is used1 either by tubular stay-bolts1 a1 a1 a1 or perforations in the door1 or both4 ,illustration3 ,fig4 #bae4 ,scale in4 #a foot4 ,in order to avoid the inconvenience and expense of replacing the fire-brick arch1 what is known as the 8,jauriet water-table0 has been extensively used on some roads4 ,this is the invention of ,mr4 ,c4 ,f4 ,jauriet and is represented in fig4 #bae1 and consists of a flat 8table10 ,b ,c1 formed of two boiler plates placed about #d in4 apart1 with the space between filled with water4 ,the two plates are stayed with ordinary stay-bolts in the same way as the sides of the fire-box4 ,the form of the water-table is similar to that of the fire-brick1 excepting that it is not arched1 this form not being necessary1 as the plates are riveted to the sides of the fire-box4 ,air is admitted above the fire both by hollow stay-bolts and holes in the door1 as shown at ,a4 ,tubes1 f1 are put into the front and lower portion of the water-table to allow the ashes and cinders1 which would otherwise be deposited above1 to fall down on the grates4 ,illustration3 ,fig4 #baf4 ,when air is admitted at the furnace door of an ordinary fire-box1 it is very apt to rush directly into the tubes without mingling with the gases4 ,it was found by some of the firemen on ,english railroads that by placing a shovel over the top of the furnace door1 the current of air which entered could thus be deflected downward1 and in this way smoke could be almost entirely prevented4 ,this led to the adoption of a hood or deflector1 ,a1 fig4 #baf1 which is made of sheet iron and is placed over the fire-box door and is arranged with a lever1 ,b1 so that it can be raised in order to be out of the way when coal is thrown on the fire4 ,it is suspended from a hook1 ,c1 from which it can easily be detached and taken out for repairs4 ,this is frequently necessary1 as the intense heat of the fire-box burns away the sheet iron of which it is made very rapidly4 ,it can be made of old boiler plate1 so that the expense of renewal is very slight4 ,when this plan is used1 a double sliding door1 shown in fig4 #bag1 is commonly used with it4 ,these doors are opened by the levers f d2 and e g1 which are all connected together4 ,with these sliding doors the opening for the admission of air can easily be regulated1 and the opening through which the lever1 ,b1 is attached to the deflector1 ,a1 can be arranged more conveniently than with a swinging door4 ,this plan has been employed by the ,rogers ,locomotive ,works4 ,illustration3 ,fig4 #bag4 ,scale in4 #a foot4 ,another plan of fire-box1 which was designed and patented by ,mr4 ,william ,buchanan1 ,master ,mechanic of the ,hudson ,river ,railroad1 and used extensively on that line1 is shown in fig4 #bah4 ,this consists of a water-table1 but it extends completely across the fire-box from the tube sheet to the back-plate1 thus dividing the fire-box into two compartments1 ,m and ,n4 ,in order to afford communication from the lower one to the upper one a round hole1 ,d1 about #bd in4 in diameter1 is put in the water-table in the position shown4 ,it will thus be seen that all the currents of gas1 smoke and air must unite in passing through this opening1 and are thus brought into close contact with each other4 ,after they enter the upper chamber and before they enter the tubes1 there is room and time for combustion4 ,the position of the lower side of the table1 it will be seen1 is similar to that of the deflector shown in fig4 #baf1 so that it acts in somewhat the same way1 by directing the currents of air1 which enter through the furnace door1 downward on the fire4 ,illustration3 ,fig4 #bah4 ,scale in4 #a foot4 ,,question #djb4 ,how do these different plans operate8 ,answer4 ,they will all burn coal more perfectly1 and therefore more economically1 if they are carefully and skillfully managed1 than is possible in ordinary plain fire-boxes2 but it is probable that more economy in the consumption of coal would result from the improvement of the practice and knowledge of firemen than can be expected from the use of any of the appliances described1 if they are used without care1 or knowledge of the principles of combustion4 ,,question #djc4 ,in what respect does anthracite coal differ from bituminous8 ,answer4 ,it differs chiefly in the fact that it contains a much larger proportion of carbon and less of hydrogen1 and in the fact that it consequently gives off very little or no coal gas4 ,its combustion is therefore more simple than that of bituminous coal1 as there is very little else than solid carbon to burn4 ,,question #djd4 ,in what kind of a fire-box is anthracite usually burned8 ,answer4 ,it is usually burned in a very long grate1 and as the heat is very intense1 the grate-bars are usually made of iron tubes1 through which a current of water circulates1 so as to prevent them from melting4 ,,question #dje4 ,is it important to admit air above an anthracite fire to facilitate combustion8 ,answer4 ,as there are no gases to be burned1 it is not so important as it is with bituminous coal1 but if the layer of anthracite on the grates is very thick1 it will be impossible to get enough air through the coal to convert all the carbon into carbonic dioxide1 and the carbon and oxygen will therefore unite so as to form carbonic oxide4 ,if air is admitted above the fire1 as has already been explained1 another equivalent of oxygen will unite with the carbonic oxide1 and a second combustion will then take place above the fire1 and the carbonic oxide will thus be converted into carbonic dioxide4 ,if1 under these circumstances1 no air was admitted above the fire1 the second combustion would not occur1 and all the heat produced thereby would be lost4 ,,question #djf4 ,how can we determine the relative value of different kinds of fuel for use in locomotives8 ,answer4 ,this can only be determined satisfactorily by actual experiment4 ,the chemical composition1 excepting so far as it indicates the presence of deleterious substances1 such as sulphur1 ashes1 clinkers1 etc41 affords but little assistance in determining the value of fuel4 ,nearly the same quantities of elements in different fuels may arrange themselves1 before and during combustion1 so as to produce very different series of compounds4 ,it is true that the composition of coal gives us some indication of its heat-producing capacity1 but the extent to which that capacity can be converted into actual steam in locomotive boilers1 depends to a very great extent upon the conditions under which the fuel is burned4 ,it should also be remembered that the rapidity with which steam can be generated is a very important matter in locomotive practice4 ,whether a heavy freight train can be taken up a given grade1 or a fast express make time1 often depends upon the amount of steam which can be generated by the fuel in each second of time that the boiler is worked to its maximum capacity4 ,therefore any appliance for improving combustion1 which reduces the quantity of steam which can be generated by the boiler in a given time1 is quite sure to fall into disuse or be abandoned4 ,it is of course often necessary to adapt the appliances for burning fuel to the fuel itself2 and when a poor quality of the latter must be used1 more boiler capacity must be given than is needed to do the same work with better fuel4 ,the table in the appendix will no doubt be valuable as indicating the properties and relative value of several different kinds of fuel used in this country4 ,the table is copied from a report made to the ,navy ,department of the ,united ,states by ,professor ,walter ,b4 ,johnson in #ahdd1 and the conclusions are deduced from a series of very elaborate experiments made for the ,navy ,department4 ,this report furnishes the most full and reliable data regarding the value of ,american fuel thus far 7#ahgd7 published2 but it contains little or no information concerning the fuels which are now used on railroads in our ,western ,states4 ,the first eight specimens of coal given in the table are anthracite2 all the rest are bituminous coals4 ,,part ,,xx4 ,,the ,,resistance ,,of ,,trains4 ,,question #djg4 ,what is meant by the resistance of trains or cars8 ,answer4 ,it is the power required to move them on the track4 ,thus if a rope1 fig4 #bai1 was attached to a car at one end1 and the other passed over a pulley1 a1 and a sufficiently heavy weight1 ,w1 was hung on the end of the rope1 it would move the car4 ,the weight ,w would then be equal to the resistance of the car4 ,illustration3 ,fig4 #bai4 ,,question #djh4 ,how can the resistance of cars under different circumstances be determined8 ,answer4 ,it has been found that it takes a force of about #f lbs4 per ton 7of #b1jjj lbs47 to move a car slowly on a level and straight track after it is started4 ,that is1 if a car weighs #bj tons and a rope1 fig4 #bai1 is attached to it at one end and the other passed over a pulley1 a1 with a weight1 ,w1 suspended to it1 it will require a weight equal to #bj #f #abj lbs4 to keep the car moving slowly4 ,if two cars of the above weight were coupled together1 it would require twice #abj or #bdj lbs41 and if three were attached to each other1 three times #abj1 or #cfj lbs41 and so on4 ,in other words1 ,,multiplying ,,the ,,total ,,weight ,,of ,,the ,,cars ,,in ,,tons 7,,of #b1jjj ,,lbs47 ,,by #f ,,will ,,give ,,us ,,their ,,resistance1 ,,or ,,the ,,force ,,required ,,to ,,keep ,,them ,,moving ,,on ,a ,,level ,,and ,,straight ,,track ,,at ,a ,,slow ,,speed ,,after ,,they ,,are ,,started4 ,the resistance is represented by the weight above1 and the locomotive must exert a force equal to that weight to keep the train moving4 ,as the speed increases the resistance increases1 as is shown by the following table4 ,it should be stated here1 however1 that our knowledge regarding this whole subject of the resistance of ,american cars and trains is exceedingly inaccurate and imperfect1 and the data given in the books are nearly all based on experiments made in ,europe1 with cars of a different construction from those used here4 ,there is reason for believing1 however1 that the resistance of ,american cars is less than that of ,european cars1 and we have assumed it to be #f lbs4 per ton on a level at very slow speed1 which is less than the resistance which is usually given1 but the following figures should be regarded merely as an approximation to the actual facts1 of which we are still in ignorance3 ,velocity of trains in miles per hour #e #aj #ae #bj #be #cj #ce #dj #de #ej #fj #gj ---------------------------------------- ----------------- ,resistance on straight line in lbs4 per ton 7of #b1jjj lbs47 #f4af4fg4ch4ci4faa4bac4aae4cag4hbj4fbgcd 4f ,now1 if we want to get the resistance at #cj miles an hour of a train of ten cars weighing each #bj tons1 the calculation would be #aj #bj #aa #b1bej lbs4 ,this will give the resistance on a level and straight track4 ,on an ascending grade the resistance is greater than that given above1 because1 besides pulling the car horizontally1 it is necessary to raise it vertically a distance equal to the ascent of the grade4 ,thus if we have a grade with a rise of forty feet in a mile1 the amount of energy required to simply raise the weight of a car would be equal to its weight in pounds multiplied by the vertical height of the ascent4 ,thus1 supposing a car which weighs #dj1jjj lbs4 to be run one mile on a grade of forty feet ascent in that distance1 then the energy expended in simply raising the car will be equal to #dj1jjj #dj #a1fjj1jjj foot-pounds4 ,now1 if it was necessary to raise that weight by a direct vertical lift or pull1 it would require a force equal to or a little greater than the load to do it4 ,but in pulling a car or train up a grade1 which is an inclined plane1 the force1 which is the locomotive1 instead of being exerted through the vertical distance is exerted through the horizontal distance1 which in this case is one mile1 or #e1bhj feet4 ,therefore1 if we divide the number of foot-pounds of energy required by the distance through which the power is exerted1 it will give us the force exerted through one foot4 ,that is1 #a1fjj1jjj --------- #aea4e lbs4 #e1bhj ,the resistance due to the ascent alone of a train on a grade or incline can therefore be calculated by ,,multiplying ,,the ,,weight ,,of ,,the ,,train ,,in ,,pounds ,,by ,,the ,,ascent ,,in ,,any ,,given ,,distance ,,in ,,feet ,,and ,,dividing ,,the ,,product ,,by ,,the ,,horizontal ,,distance ,,in ,,feet4 ,thus in the above example the rate of the ascent is given in so many feet per mile2 we therefore multiply by #dj and divide by #e1bhj1 which is the number of feet in a mile4 ,if the rate of the gradient had been given1 as it sometimes is1 as #a in #acb1 we would simply have divided the weight of the train by the latter number4 ,if we want to get the resistance per ton of train we substitute for its weight that of one ton in pounds2 thus3 #b1jjj #dj ---------- #ae4a lbs4 #e1bhj ,if1 now1 we have the resistance which is due to the ascent or gravity alone1 we must add to this the resistance on a straight and level track1 at the speed at which the train runs1 in order to determine the total resistance on the grade4 ,on a level road at a speed of #e miles per hour it would be #f4a lbs4 per ton1 so that on a grade of forty feet to a mile at that speed the resistance would be #f4a #ae4a #ba4b lbs41 per ton1 and at #aj miles it would be #f4f #ae4a #ba4g lbs41 and at #cj miles per hour on the grade the resistance would be #aa4b #ae4a #bf4c lbs4 per ton4 ,to get the total resistance on a grade for any speed1 we ,,add ,,the ,,resistance ,,for ,,that ,,speed ,,on ,a ,,straight ,,and ,,level ,,line ,,to ,,the ,,resistance ,,due ,,to ,,the ,,ascent ,,alone4 ,the resistances for various rates of speed and grades has been calculated1 and is given in the table in the appendix4 ,the top horizontal row of figures of that table gives the rates of speed4 ,the left-hand vertical row gives the rise of grade in feet per mile4 ,the resistance for any given grade and speed is given where the vertical row of figures under the rate of speed and the horizontal row opposite the rise of the grade intersect each other4 ,thus1 for a grade of #cj feet per mile and a speed of #de miles per hour1 we follow the vertical column under the #de downward1 and the horizontal column opposite #cj to the right1 and where the two intersect the resistance1 #bi4a lbs4 is given4 ,,question #dji4 ,what effect do curves have on the resistance of trains8 ,answer4 ,they increase the resistance1 but in what proportion or to what degree is not known accurately4 ,european authorities say that the resistance is increased1 over what it would be in a straight and level line1 about #a per cent4 for every degree of the curve occupied by a train4 ,it is probable1 however1 that the resistance of ,american cars1 which nearly all have double trucks1 is not so great on curves as that of ,european cars1 which nearly all have long and rigid wheel-bases1 and whose wheels therefore can not adjust themselves so easily to the curvature of the track as they can when the ,american system of double trucks is used4 ,,question #daj4 ,what is meant by a degree of a curve8 ,answer4 ,in order to measure circles1 they are all supposed to be divided into #cfj equal parts1 which are called degrees4 ,one degree of a curve is therefore of a complete circle2 but if the curve has a long radius1 one degree of such a curved track will be longer than one degree of a curve with a short radius1 but each will have the same amount of 8bend0 or curvature4 ,it is this latter which increases the resistance of trains1 and the greater the number of degrees of a curve occupied by a train of cars1 the greater will be the 8bend0 of the track1 and therefore the greater the resistance4 ,,question #daa4 ,what other causes affect the resistance of trains8 ,answer4 ,the condition of the track and the force and direction of the wind4 ,on a rough track the resistance is very much greater than on a smooth one1 and a strong head-wind makes it much more difficult to pull a train than it is in calm weather4 ,,part ,,xxi4 ,,proportions ,,of ,,locomotives4 ,,question #dab4 ,in proportioning a locomotive to any given kind of work1 what are the first facts which should be known8 ,answer4 ,we should first know the weight of the train which the locomotive must draw2 second1 the speed at which it must run2 and third1 the steepest grades and the shortest curves of the road on which it must work4 ,from these data the resistance of the train which the locomotive must overcome can be at least approximately determined4 ,,question #dac4 ,when the greatest resistance of the train is known1 what is the next thing to be determined8 ,answer4 ,as was stated in answer to ,question #ff1 if the wheels revolve and their adhesion is greater than the resistance opposed to the movement of the locomotive1 the latter will overcome the resistance2 but if the latter is greater than the friction1 the wheels will slip4 ,it therefore follows that the adhesion must be somewhat greater than the resistance4 ,as the adhesion is equal to about one-fifth#ajj of the adhesive weight or pressure of the driving-wheels on the rails1 obviously this weight should be five times the resistance4 ,thus1 if we have a train weighing #djj tons which we want to take up a grade of #dj feet per mile at a speed of #bj miles per hour1 its resistance1 calculated from the table given in the previous part1 would be #i1cfj lbs4 ,therefore1 #i1cfj #e #df1hjj lbs4 the required adhesive weight4 #ajj ,see answer to ,question #cji4 ,,question #dad4 ,what considerations determine the manner of distributing this weight on the wheels8 ,answer4 ,it is found by experience that if too much weight is placed upon one wheel1 the material of which the rails are made is partly crushed and injured1 and they then wear out much more rapidly than they would if the weight was distributed on more wheels1 and thus a smaller amount of weight rested on each point of contact with the rails4 ,the amount of weight which can be carried on a single wheel depends upon the material of which the rails are made1 and to some extent on their form and size1 or as the latter is usually expressed1 on their weight per yard4 ,,question #dae4 ,when the adhesive weight and the number of driving-wheels are known1 how is the size of the latter and of the cylinders determined8 ,answer4 ,the size of the wheels will to a certain extent depend upon the speed1 because the larger the wheels1 the further will the locomotive move in one revolution2 but no exact rule can be given for their size4 ,at present there is still a great diversity of opinion among engineers regarding the best sizes of wheels and cylinders for any given service4 ,probably the safest plan will be to consult the best practice1 and in the absence of any better reasons be guided for the present by that4 ,in this country the most common size of locomotives used is that which we have selected for our illustrations1 that is1 what are called five-feet wheels1 and cylinders of #af inches diameter and #bd inches stroke4 ,more engines of these dimensions are used than of any other4 ,for freight service the wheels are sometimes made of smaller and for passenger trains of larger diameter2 but locomotives with driving-wheels and cylinders of the dimensions given are used for both passenger and freight service4 ,it should be stated here that what are called five-feet wheels are usually about #a in4 larger in diameter than five feet4 ,this arose from the fact that the tires which are now used are made thicker than they were on the first engines1 and the practice thus established has been continued4 ,we will therefore take the diameter of what is called a five-feet wheel at what it really is1 #fa in4 ,such locomotives also have about #dj1jjj lbs4 of adhesive weight4 ,now1 the circumference of such wheels is #aic4b in41 and therefore in one revolution of the wheels1 if they do not slip1 the locomotive will move that distance on the rails4 ,at the same time each piston will sweep through the cylinder twice1 and therefore in one revolution #d times one cylinder full of steam is used4 ,now a cylinder of #af in4 diameter and #bd in4 stroke contains or will hold #d1hbe cubic inches1 so that in one revolution of the wheels #d1hbe #d #ai1cjb cubic inches of steam are used4 ,as has been stated1 in one revolution of the wheels1 if they do not slip1 the locomotive will move #aic4b in4 ,if1 now1 we divide #ai1cjb by #aic4b it will give us the amount of steam used to move the locomotive and train one inch4 ,now1 #ai1cjb #aic4b #ii4i1 which1 for the sake of even figures we will call #ajj4 ,we thus see that a locomotive with #dj1jjj pounds or #bj tons 7of #b1jjj lbs47 of adhesive weight requires #ajj cubic inches of cylinder capacity#aja to move it one inch4 ,now1 if a locomotive had only half as much weight on the driving-wheels1 it could pull only half as much load1 and would therefore use only half as much steam1 and consequently need only half the cylinder capacity of the other locomotive4 ,if there was three-quarters or a third as much adhesive weight1 the cylinder capacity should also be three-quarters or a third4 ,we thus see that the cylinder capacity should be proportioned to the total adhesive weight4 ,now as #ajj cubic inches of cylinder capacity are needed to move an engine with #bj tons adhesive weight one inch1 if we divide #ajj by #bj we will get the cylinder capacity needed for each ton4 ,that is1 #ajj #bj #e ,,cubic ,,in4 ,,cylinder ,,capacity ,,per ,,ton 7of #b1jjj lbs47 ,,of ,,adhesive ,,weight ,,is ,,needed ,,to ,,move ,,any ,,locomotive ,,one ,,inch4 ,this quantity we have named the modulus of propulsion4 #aja ,the cylinder capacity is the space swept through by the two pistons4 ,in the above illustrations what is meant is1 that the average space in the cylinder swept through by the piston is #ajj cubic inches for each inch that the locomotive advances4 ,supposing now that it is required to calculate the cylinder capacity for a locomotive with #ae tons adhesive weight1 and wheels #d feet or #ed in4 in diameter4 ,we will first multiply #ae by the modulus of propulsion1 #ae #e #ge the number of cubic inches of cylinder capacity required to move such a locomotive one inch4 ,multiplying the length of the circumference of the wheels1 which in this case is #afi4f in4 by #ge1 will give us the total cylinder capacity for one revolution4 ,that is #afi4f #ge #ab1gbj cubic inches of cylinder capacity1 or the space which should be swept through by the two pistons4 ,dividing this by #d will give us the cubical contents in inches of one of the cylinders4 ,thus1 #ab1gbj #d #c1ahj cubic inches the capacity of one cylinder4 ,now as the capacity of a cylinder is calculated by multiplying the area of the piston by the length of the stroke1 if we have the one we can easily determine the other4 ,thus1 supposing it was intended to make the stroke of the pistons #bb in41 dividing #c1ahj by #bb will give us the area of the piston4 ,thus1 #c1ahj #bb #add4e square inches4 ,now by the well-known rule in mensuration1 if we ,,divide ,,the ,,area ,,of ,a ,,circle ,,by #j4ghed1 ,,the ,,square ,,root ,,of ,,the ,,quotient ,,will ,,be ,,the ,,diameter ,,of ,,the ,,circle4 ,thus1 #add4e #j4ghed #ahc4i4 ,the square root of #ahc4i is #ac nearly1 which should be the diameter of the cylinder4 ,instead of calculating the diameter of the circle1 a more convenient way is to refer the area to a table of areas1 and from it find the diameter4 ,of course if we have the diameter of the piston and want to get the stroke1 we ,,divide ,,the ,,cubical ,,contents ,,of ,,the ,,cylinder ,,by ,,the ,,area ,,of ,,the ,,piston4 ,thus1 in the present illustration1 if it was intended to have the piston #ac in4 diameter1 we would have divided #c1ahj by the area of a piston #ac in4 diameter1 which is #adc4a1 so that we would have #c1ahj #adc4a #bb nearly1 inches of stroke of piston4 ,from the above considerations we can deduce the following ,,rule ,,for ,,calculating ,,the ,,capacity ,,of ,,the ,,cylinders ,,when ,,the ,,adhesive ,,weight ,,is ,,known3 ,,multiply ,,the ,,total ,,weight ,,on ,,the ,,driving-,,wheels ,,in ,,tons 7of #b1jjj lbs47 ,,by #e1 ,,and ,,then ,,by ,,the ,,circumference ,,of ,,the ,,wheels ,,in ,,inches1 ,,and ,,divide ,,by #d4 ,,the ,,quotient ,,will ,,be ,,the ,,cubical ,,contents ,,in ,,inches ,,of ,,each ,,cylinder4 ,from this1 if either the diameter or stroke is given the other can easily be found1 as has been explained4 ,it should be remarked here that it is unimportant1 so far as the power of the locomotive is concerned1 whether the cylinders have a large diameter and a short stroke or a small diameter and a long stroke1 provided the cubical contents are the same4 ,thus cylinders #ag in4 in diameter and with #bj in4 stroke would have almost exactly the same capacity and the same power would be exerted with them as with cylinders #af #bd in42 the only difference would be that with the cylinder of the largest diameter the pressure on the piston and consequently on the crank-pin journal and the strain on the parts would be greater than with the smaller cylinder4 ,the difference in pressure would1 however1 be exactly compensated by the loss or gain in the leverage exerted through the driving-wheels on the rails4 ,,question #daf4 ,what circumstances should determine the size of locomotive boilers8 ,answer4 ,they should be proportioned to the amount of adhesive weight1 and to the speed at which the locomotive is intended to work4 ,thus1 a locomotive with a great deal of weight on the driving-wheels could pull a heavier load and would1 by the above rule for proportioning the cylinders1 have a greater cylinder capacity than one with little adhesive weight1 and would therefore consume more steam1 and therefore should have a larger boiler4 ,it is also obvious that if a locomotive like that shown in plates ,i and ,,ii should have a boiler just large enough to furnish steam when running at the rate of #bj miles an hour1 it would be too small if the locomotive ran #dj miles an hour1 the train resistance being the same in both cases4 ,driving-wheels #e feet in diameter would at #bj miles per hour make #aab revolutions per minute1 and would therefore consume #ddh cylinders full of steam4 ,at #dj miles per hour double the number of revolutions would be made1 and consequently twice the quantity of steam would be used1 and therefore the boiler should have twice the steam-producing capacity4 ,if1 therefore1 we know the size of a boiler required for a given amount of adhesive weight and a given speed1 we can easily calculate the boiler capacity for any other weight and speed4 ,,question #dag4 ,how can we determine the boiler capacity needed for an engine with a given amount of adhesive weight and for a given speed8 ,answer4 ,this must be determined empirically1 that is from experience4 ,,question #dah4 ,on what does the steam-generating capacity of a boiler depend8 ,answer4 ,first1 upon the size of its grate and fire-box1 because more fuel can be burned in a large fire-place than in a small one2 second1 on the amount of heating surface to which the products of combustion are exposed1 and third1 on the draft produced by the blast or exhaust steam4 ,of course the amount of steam generated is also dependent upon a great variety of other circumstances1 such as the nature of the combustion1 the firing1 the arrangement of the fire-box1 grates1 etc41 and the condition of the heating surfaces2 but these have nothing to do with the proportions or size of the boiler4 ,,question #dai4 ,what are the proportions of boilers used in locomotives like that which has been illustrated in these articles and represented in ,plates ,i and ,,ii8 ,answer4 ,the area of the grate is about #b1ajj square inches and the total heating surface about #hjj square feet1 and the water capacity about #e1jjj lbs41 and the total weight of the boiler1 including all the boiler attachments and appliances for promoting combustion1 about #cj1jjj lbs4 ,,question #dbj4 ,at what speed are such engines usually run8 ,answer4 ,the speed varies so much under different circumstances1 that it is impossible to give even approximately the average speed of such engines4 ,,question #dba4 ,how then can we determine the proper proportions of a boiler for a locomotive intended for any given service8 ,answer4 ,as stated before1 this can only be done empirically4 ,the safest method is to select a locomotive which is doing the best service1 and learn the average speed at which it runs1 the size of its grate and the amount of its heating surface1 and its adhesive weight4 ,,now ,,multiply ,,the ,,above ,,speed ,,in ,,miles ,,per ,,hour ,,by ,,the ,,adhesive ,,weight ,,of ,,the ,,locomotive ,,in ,,tons 7of #b1jjj lbs47 ,,and ,,divide ,,the ,,product ,,into ,,the ,,area ,,of ,,the ,,grate ,,in ,,square ,,inches4 ,,then ,,multiply ,,the ,,adhesive ,,weight ,,of ,,the ,,locomotive ,,for ,,which ,,the ,,boiler ,,is ,,to ,,be ,,provided ,,by ,,its ,,speed1 ,,in ,,miles ,,per ,,hour1 ,,and ,,by ,,the ,,quotient ,,obtained ,,above3 ,,the ,,product ,,will ,,be ,,the ,,area ,,of ,,the ,,grate ,,in ,,square ,,inches ,,for ,,the ,,new ,,engine4 ,to illustrate this1 suppose an engine of the dimensions given to run at an average speed of #bj miles per hour4 ,now1 multiplying that speed by the number of tons of adhesive weight and dividing the product into the area of the grate1 we have #bj #bj #djj and #bajj #djj #e4be4 ,we now want to determine the size of a grate for the boiler of a locomotive with #cj tons adhesive weight and to run at a speed of #ae miles per hour4 ,we therefore multiply #ae by #cj and the product by the above quotient1 or #ae #cj #e4be #b1cfb4e square inches of grate surface for the boiler4 ,the required heating surface can be obtained in a similar way1 by substituting it instead of the grate surface in the calculations4 ,,question #dbb4 ,how is the size of locomotive boilers usually limited8 ,answer4 ,by the weight of the locomotive and to some extent by the distance between the rails4 ,it will be found often that it is impossible to make the boiler of the size indicated by a calculation similar to the above without at the same time making the weight of the locomotive and the adhesive weight greater than was assumed4 ,the result of such a calculation indicates1 therefore1 that too large a proportion of the weight of the locomotive is on the driving-wheels for the speed at which it is intended to work1 and that either they should bear less weight or the speed be reduced4 ,,question #dbc4 ,in what respects is the operation of locomotive boilers different from that of nearly all other steam boilers8 ,answer4 ,the amount of steam generated in proportion to the amount of heating surface is much greater in locomotive boilers than in any other kind4 ,to produce combustion which will be sufficiently active to generate the requisite quantity of steam1 the fire must be stimulated by the blast created by the exhaust steam to a degree unknown in other kinds of boilers4 ,so rapid is the movement of the products of combustion that a smaller proportion of the heat is imparted to the water contained in the boiler1 and consequently a less amount of water is evaporated in proportion to any given amount of fuel than in boilers in which combustion is less violent4 ,the combustion is also less perfect1 because the strong draft does not allow time for a perfect combination of the gases which produce combustion4 ,the supply of steam which a locomotive boiler must furnish is also much more irregular than the demands made upon any other kind of boiler4 ,at one time the fire must be urged to the greatest possible intensity in order to furnish steam enough to pull a train up a steep grade4 ,when the top is reached the demand ceases1 and the boiler can be cooled4 ,the load which a locomotive can pull over a given line of road is usually limited by the utmost capacity of the boiler to supply steam at these critical periods4 ,,question #dbd4 ,what relation is there between this irregular action and the size of the boiler8 ,answer4 ,the smaller the boiler1 or rather the larger the amount of steam which must be generated in a given time in proportion to the heating surface1 the more must the fire be urged2 and therefore the smaller the boiler in proportion to the work it must do1 the less will be its economy4 ,in order to produce a rapid combustion in a small boiler1 it is necessary to contract the exhaust nozzles in order to create a draft strong enough4 ,in doing this the back pressure on the pistons is very much increased1 and when the blast becomes very violent a great deal of solid coal is carried through the tubes and escapes at the smoke-stack unconsumed4 ,at the same time large quantities of unconsumed gases escape1 because there is not time for combustion to take place in the fire-box4 ,the fact that with a violent draft the flame and smoke are in contact with the heating surface for a sensibly shorter period of time also has its influence2 as less heat will be imparted to the water if the products of combustion are only of a second instead of in passing through the tubes4 ,there is another consideration which should be taken into account in this connection1 which is1 that if a boiler is so small that it is worked nearly up to its maximum capacity at all times1 it will be impossible to accumulate any reserve power in it in the form of water heated to a high temperature to be used as occasion may require4 ,with a boiler having a great amount of heating surface and capacity for carrying a large quantity of water1 the latter can be heated at times when the engine is not working hard1 and the heat thus stored up in the water can then be used when it is most needed4 ,thus we will suppose that to pull a train of cars on a level #bej lbs4 of steam are consumed per mile4 ,on a grade of #cj feet per mile the resistance will be three times what it is on a level1 and therefore three times the quantity of steam will be consumed1 so that the boiler must then evaporate #gej lbs4 of water per mile4 ,now to convert #bej lbs4 of water heated up to a temperature due to #acj lbs4 of effective pressure1 or #cee4f degrees1 into steam of that pressure will require #baf1ege units of heat4 ,if at the same time that this steam is being consumed1 we pump into the boiler #bej lbs4 of water of a temperature of #fj degrees1 #gc1ijj more units of heat will be needed to raise the water to the temperature due to #acj lbs4 effective pressure1 so that on the level part of the road it would be necessary to transmit to the water in the boiler #baf1ege #gc1ijj #bij1dge units of heat in a mile4 ,if there is no room in the boiler for storing a surplus quantity of hot water1 it will be necessary on a grade as fast as the steam is consumed to feed an equivalent amount of cold water to take the place of that which was converted into steam1 so that on a #cj feet grade it would be necessary to convert at the rate of #gej lbs4 of hot water into steam in a mile1 which would require #fdi1gbe units of heat1 and at the same time heat an equal amount of cold water to a temperature due to the pressure of the steam1 which would require #bba1gjj more units4 ,so that it will be necessary to transmit at the rate of #hga1dbe units of heat to the water per mile4 ,now if the boiler was so large that more water could be pumped into it and heated than was used on the level portion of the road1 and could there be stored up for future use1 the pumps might be either partly or entirely shut off when the engine was working the hardest on the grade4 ,in this way1 instead of being obliged to convert hot water into steam1 and at the same time heat an equal amount of cold feed-water1 there would be a surplus of hot water stored up already heated4 ,it would therefore only be necessary to convert this hot water into steam1 which will require a transmission of heat to the water at the rate of #fdi1gbe units of heat instead of #hga1dbe4 ,it must be remembered that on nearly all roads there are certain difficult places which practically limit the capacity of the locomotives on that line4 ,if therefore the capacity of the engines can be increased at those points1 their capacity over the whole line is increased4 ,it will be seen by the above illustration that by having a large boiler it is necessary for it to do very much less work at the critical period1 when1 as every locomotive runner knows1 it is often of the utmost importance to make use of every possible available means in order to pull the trains4 ,it is true that on a very long grade the supply of surplus hot water would soon be exhausted1 but even in such cases there is usually one place1 owing to a curve or other cause1 which is more difficult to surmount than any other1 in which case it will be necessary to use more steam for a short time than the locomotive can generate if the boiler is fed continuously4 ,for such cases a surplus of water can be used4 ,but even if the resistance is equal over the whole length of the incline1 still the large boiler will have the advantage1 because it can at all times generate more steam than a smaller one4 ,it may therefore1 we think1 safely be assumed that locomotive boilers should always be made as large as the weight of the locomotive will permit4 ,,question #dbe4 ,what effect does the size of the driving-wheels have upon the combustion and evaporation of locomotive boilers8 ,answer4 ,as small wheels make more revolutions in running a given distance than large ones1 there will be more strokes of the piston with the former than with the latter1 if the locomotive in both cases runs at the same speed4 ,as smaller cylinders are usually employed with small wheels1 the blast up the chimney is then composed of a larger number of discharges of steam1 but each one of less quantity1 than when larger wheels and cylinders are used4 ,in the one case the 8puffs0 of steam are many and small1 and in the latter few and large4 ,if the cylinders are proportioned by the rule which has been given for that purpose1 the amount of steam discharged in running any given distance will be the same with engines having large and those with small wheels1 the only difference being that it will be subdivided into a greater number of discharges in the one case than in the other4 ,now1 it is found that the draft of engines is much more effective on the fire when the blast is thus subdivided1 that is when small wheels and cylinders are used1 than it is with large ones1 and therefore more steam is generated with the former than with the latter4 ,,question #dbf4 ,what relation is there between the size of the wheels and that of the boiler8 ,answer4 ,as has been explained1 the size of the boiler is limited by the weight of the locomotive4 ,the boiler and its attachments of an ,american locomotive1 when the former is filled with water1 weigh about half as much as the locomotive2 therefore unless we increase the weight of the latter or decrease the weight of the machinery1 we can not increase the size of the boiler4 ,now1 large wheels are heavier than small ones2 they require larger cylinders1 stronger connections1 heavier frames1 and in fact nearly all the parts of the machinery used with large wheels must be heavier than are required when small wheels are used4 ,therefore1 by decreasing the size of the wheels all the other parts of the engine proper can be made lighter than is possible if large wheels are used1 and thus the size and weight of the boiler can be increased without increasing the whole weight of the locomotive4 ,there is of course a practical limit below which the size of the wheels can not be reduced1 because the speed of the piston would become so great as to be injurious to the machinery4 ,by reducing the stroke1 however1 with the diameter of the wheels1 the evil referred to may be obviated to a great extent4 ,a cylinder with a large diameter and comparatively small stroke has also the advantage that there is less surface exposed to radiation of heat than there is in a cylinder in which these proportions are reversed4 ,,part ,,xxii4 ,,different ,,kinds ,,of ,,locomotives4 ,,question #dbg4 ,into what classes may locomotives be divided conveniently8 ,answer4 #a4 ,locomotives for 8switching10 8shunting0 or 8drilling0 service1 that is1 for transferring cars from one place to another at stations2 #b1 for freight traffic2 #c1 for ordinary passenger traffic1 and #d1 for suburban or metropolitan railroads1 where a great many light trains are run4 ,,question #dbh4 ,what kinds of locomotives are used in this country for switching cars at stations8 ,illustration3 ,fig4 #bbj4 ,answer4 ,four-wheeled locomotives similar to that shown in ,plate ,,iv4 ,in some cases they are made with six driving-wheels4 ,engines like that shown in ,plate ,,iv have separate tenders1 but they are sometimes made so as to carry the water-tank and fuel on the locomotive itself1 as shown in fig4 #bbj1 and are then called tank locomotives4 ,fig4 #bbj represents a switching engine built by the ,taunton ,locomotive ,manufacturing ,company4 ,,question #dbi4 ,why are four-wheeled locomotives used for switching8 ,answer4 ,because in such service it is constantly necessary to start trains1 many of which are very heavy1 and therefore a great deal of adhesion is needed4 ,for this reason the whole weight of the locomotive and in the case of tank locomotives that of the water and fuel is placed on the driving-wheels4 ,it is also necessary for such locomotives to run over curves of very short radius and into switches whose angle with the main track is very great1 and therefore in order that they may do this and remain on the track1 their wheel-bases must be very short1 and consequently the wheels are all placed near together between the smoke-box and fire-box4 ,,question #dcj4 ,why are such locomotives not suited for general traffic8 ,answer4 ,owing to the shortness of their wheel-bases they become very unsteady at high speeds1 and acquire a pitching motion1 similar to that of a horse-car when running rapidly over a rough track4 ,this unsteadiness not only becomes very uncomfortable to the men who run the locomotive1 but there is danger of the engine running off the track4 ,as nearly all switching is done at very slow speeds1 it is not so objectionable for that service as it would be on the 8open road0#ajb at high speeds4 #ajb ,the term 8open road0 is a literal translation from the ,german1 for which there is no corresponding ,english term1 and means the road between stations where trains run fast4 ,,question #dca4 ,what kinds of locomotives are used for freight service8 ,answer4 ,the greater part of the freight service of this country is performed by locomotives like that selected for the illustrations of these articles1 and represented in ,plates ,i1 ,,ii and ,,iii4 ,such locomotives have been called 8,american0 locomotives because they first originated in this country and are now more generally used here than anywhere else4 ,side elevations of locomotives of this kind1 built by the ,baldwin ,locomotive ,works1 the ,grant ,locomotive ,works1 the ,danforth ,locomotive and ,machine ,company1 the ,mason ,machine ,works and the ,hinkley ,locomotive ,works are represented in ,plates ,v1 ,,vi1 ,,vii1 ,,viii and ,,ix4 ,such locomotives have been described in the preceding pages4 ,,question #dcb4 ,what are the dimensions of such engines8 ,answer4 ,the principal dimensions of the engines illustrated are given in the table in the appendix1 but locomotives of this plan are built of much smaller and also of larger sizes than those represented by the engravings4 ,in some cases such locomotives do not weigh more than #ce or #cf1jjj lbs41 with cylinders from #h to #ab inches in diameter4 ,in other cases they weigh as much as #ff1jjj lbs41 with cylinders #ag or #ah inches in diameter4 ,the wheels vary from #d to #f feet in diameter1 but the most common sizes are #d and #e feet4 ,,question #dcc4 ,when it is desirable to pull heavier loads than is possible with the adhesive weight that can be placed on four driving-wheels1 what is done8 ,answer4 ,one or more pairs of driving-wheels are added1 as in the ten-wheeled locomotive represented in ,plate ,x1 the 8,mogul0 engine1 ,plate ,,xi1 and the 8,consolidation0 engine1 ,plate ,,xii4 ,the ten-wheeled locomotive1 it will be seen1 is similar in construction to an ordinary ,american locomotive1 excepting that it has another pair of driving-wheels in front of the main driving-wheels4 ,it will be seen1 however1 that it is necessary to keep these close to the latter1 because if they are brought further forward they will be too near the back truck-wheels4 ,for this reason a truck consisting of a single pair of wheels1 ,a1 ,a1 is placed in front of the cylinders1 as represented in ,plates ,,xi and ,,xii1 is now much used4 ,the front driving-wheels are then placed further forward1 and thus bear a larger proportion of weight than they do in locomotives like that shown in ,plate ,x4 ,,question #dcd4 ,how are trucks with a single pair of wheels constructed8 ,answer4 ,the truck frame is extended some distance behind the truck-axle1 as shown in fig4 #bba1 and the centre-pin1 a1 about which it vibrates1 is placed at the back end4 ,the weight of the locomotive1 or that portion to be carried on the truck1 is then made to rest over the centre of the axle1 but in such a way that it can move laterally or crosswise over the track4 ,such trucks were first made so that the weight of the engine rested on slides on the truck frame1 but recently they are nearly always suspended on links1 so that they can swing like a pendulum1 as shown in figs4 #aij and #aia4 ,the weight of the engine then rests on the centre-plate1 ,h ,h2 which forms part of the plate1 ,b ,b4 ,this is suspended by links1 ,l ,l1 represented by dotted lines1 which are attached by bolts to the cross-pieces1 m m1 which are fastened to the truck frame4 ,in this way the truck-wheels can move sideways independent of the engine itself4 ,as the wheels and axles1 ,a ,a1 must move about the centre-pin1 a1 fig4 #bba1 the axle assumes a radial position to the curves of the track4 ,it does this1 too1 quite independent of the driving-wheels1 as is shown in fig4 #bba1 which represents a plan of the wheels on a curve4 ,it will be seen that the truck is not at all influenced by the position of the driving-wheels4 ,this arrangement therefore gives great flexibility to the wheel-base1 and enables the wheels to adjust themselves to any lateral curvature or alignment of the track4 ,illustration3 ,fig4 #bba4 ,scale in4 #a foot4 ,,question #dce4 ,for what purpose are locomotives like that shown in ,plates ,,xi and ,,xii used8 ,answer4 8,mogul0 locomotives are often used for ordinary freight service where heavy trains must be hauled1 and also on steep grades4 8,consolidation0 locomotives1 represented in ,plate ,,xii1 which have eight driving-wheels1 are employed almost exclusively for traffic over heavy mountain grades4 ,,question #dcf4 ,what other kinds of locomotives are used for freight traffic8 ,answer4 ,various kinds of tank locomotives1 that is1 locomotives which have no separate tenders1 but carry the water-tanks and fuel on the frame and wheels of the locomotive itself1 have been devised and are to some extent used4 ,plate ,,xiii represents a locomotive of this kind on which the tanks are placed on each side of the boiler1 and the fuel on a ,bissell truck at the back end4 ,a similar truck is placed at the front end1 so that a locomotive of this kind can run equally well either way4 ,the lateral movement of the two trucks also gives great flexibility to the wheel-base1 so that such an engine will adjust itself easily to the curvature of the track4 ,if1 however1 the two pairs of truck-wheels should both stand on an elevated part of the track1 and the driving-wheels on a depression1 the latter would evidently not carry as much and the truck-wheels would carry more of the weight of the engine than they did on a level part of the track4 ,if the reverse condition of things should occur1 that is1 if the driving-wheels should be on an elevation and one or both pairs of the truck-wheels on a depression1 then the latter would bear less weight than they did and the driving-wheels more4 ,for this reason1 in order to distribute the weight evenly on all the wheels1 it is necessary to equalize the weight on the truck and driving-wheels1 by connecting them with equalizing levers1 similar to those which were described in answer to ,question #cja4 ,these levers distribute any undue weight which may come on one wheel to that next to it4 ,this is important1 because if the driving-wheels bore less weight at some times than at others1 their adhesion and their capacity to draw loads would be reduced in like proportion4 ,it is evident1 however1 that if the water-tank or fuel is carried on the driving-wheels1 there will be a greater weight on them when the tank is full than when it is empty1 and that therefore there will either be so much weight on the wheels at one time as to be injurious to the rails1 or else there will be too little for adhesion at another4 ,of course cases are conceivable1 and doubtless exist in practice1 where more adhesion is required to start a train and haul it during the first part of the 8run0 than will be needed during the latter part4 ,in such cases doubtless the variable character of the weight might be an advantage instead of the reverse1 but for ordinary practice a variable load on the driving-wheels would have the disadvantages which have been described4 ,for this reason tank locomotives have been built like that represented in ,plate ,,xiv4 ,in this it will be seen that the weight of the water-tank rests on a four-wheeled truck at the back end4 ,a ,bissell or two-wheeled truck is1 however1 placed in front in the same position as in the engine represented in ,plate ,,xiii1 and carries a portion of the weight of the boiler and machinery4 ,in order to get all the advantages which a four-wheeled switching engine possesses in having its whole weight on the driving-wheels1 and at the same time avoid the disadvantages which result from a short wheel-base1 and also from a varying amount of weight on the driving-wheels1 a locomotive like that represented in ,plate ,,xv was designed by the writer with the whole weight of the boiler and machinery resting on the driving-wheels1 and the water and fuel on a truck4 ,by this means not only the objections to carrying the weight of the water on the driving-wheels is overcome1 but at the same time the disadvantages arising from the short wheel-base of the switching locomotive1 ,plate ,,iv1 are also obviated4 ,that is1 all the permanent weight of the boiler and machinery of such a locomotive rests on the driving-wheels1 and is therefore all adhesive weight1 as it is in the switching engine1 and at the same time by extending the frame beyond the fire-box and placing the water-tank and fuel on this extension of the frame and supporting their weight on a truck1 the engine has a wheel-base which is as long and as flexible as that of ordinary ,american engines1 represented in ,plates ,v1 ,,vi1 ,,vii1 ,,viii and ,,ix1 and as the latter have only about two-thirds of their weight on the driving-wheels1 locomotives like that represented in ,plate ,,xv1 of the same weight as the others1 have fifty per cent4 more adhesion1 or they may be one-third lighter and have the same adhesion4 ,as was explained in answer to ,question #bfj1 if an ordinary ,american locomotive runs backwards1 that is1 with the driving-wheels in front1 the friction of their flanges against the rails on curves of short radius will be very excessive4 ,to avoid this with locomotives of the design last described1 they are run with the truck first1 which1 being at the opposite end of the boiler from the position which it usually occupies1 reverses the position of the boiler and other parts relative to the motion of the engine4 ,that is1 the fire-box is then in front and the smoke-stack behind4 ,engines of this kind have been built and are now working and doing excellent service2 but the prejudice which exists against running locomotives in the reverse direction to what has been customary seems to be the chief obstacle in the way of their use4 ,another plan which possesses all the advantages of the locomotive described above and is free from the last objection is represented in ,plate ,,xvi4 ,this plan was first adopted by ,mr4 ,robert ,fairlie in ,england1 but has been introduced into this country and very much improved by ,mr4 ,william ,mason1 of ,taunton1 ,mass4 ,in these locomotives1 the driving-wheels and cylinders are attached to a truck frame which turns around a centre-pin like any ordinary truck4 ,the steam and exhaust pipes are connected to the boiler and cylinder with pipes which have flexible joints4 ,by this means the truck can move independently of the boiler1 and thus the driving-wheels can adjust themselves to the curvature of the track1 just as the wheels of any other truck do1 and therefore the driving-wheels can be run ahead just as well as the truck-wheels which carry the tank4 ,this plan possesses the additional advantage that the fire-box can be made as wide and as long as may be desired without interfering with the driving-wheels4 ,the flexible pipes are1 however1 usually considered an objection2 but with the improvements which have been made in their design and construction1 the difficulties which were at first encountered have probably been overcome4 ,at any rate if there is no other objection to the use of such locomotives1 ingenuity and care should in time overcome that one4 ,plate ,,xvii represents a locomotive of this plan1 with six driving-wheels and a six-wheeled carrying truck under the tank4 ,this latter plan of locomotive is intended for heavy freight traffic4 ,,question #dcg4 ,what kind of locomotives is used for passenger trains8 ,answer4 ,eight-wheeled ,american locomotives are used almost exclusively for passenger service4 ,usually the driving-wheels of such locomotives are larger in diameter than are used for freight traffic4 ,their size varies from #e feet to #e ft4 #i in4 in diameter4 ,the locomotive by the ,mason ,machine ,works represented in ,plate ,,viii has #e feet driving-wheels4 ,for very heavy express trains locomotives with #ag #bd inch cylinders and weighing #cd tons are now used on many through lines4 ,,question #dch4 ,what is meant by suburban and metropolitan railroads1 what is the nature of their traffic1 and what kinds of locomotives are needed for it8 ,answer4 ,the traffic of suburban railroads consists chiefly of the transportation of passengers who do business in the city to the latter in the morning and to their homes in the evening4 ,as the largest number of passengers must be carried during a few hours in the morning and evening1 it is necessary to run very heavy trains at those times4 ,as the passengers must be distributed at many stations which are near together1 it is necessary to stop often2 and in order that the average speed may be reasonably fast the trains must run very rapidly between these stations4 ,it is therefore necessary to have heavy locomotives1 with more than the usual proportion of adhesive weight1 so that the trains can be started quickly without slipping the wheels4 ,the main valves should also have a liberal amount of travel1 so that steam will be admitted to and exhausted from the cylinders quickly4 ,in some cases it is thought desirable to have locomotives which will run equally well either way1 so that it will not be necessary to turn them around at each end of the 8run40 ,by metropolitan railroads are meant railroads in large cities4 ,they may be divided into two classes1 one for carrying freight cars from the outskirts of cities to the warehouses and stores at their business centres1 and also from the terminus of one road to that of another4 ,metropolitan railroads of this kind are usually branches of lines which extend from the city4 ,locomotives for such traffic must have great tractive power1 in order to pull heavy trains1 and as the speed is usually slow the wheels and the boiler capacity may be small4 ,they must generally be capable of running through curves of very short radius2 and as the traffic is usually carried through streets in close proximity to buildings1 the locomotives should be as nearly as possible noiseless4 ,the other class of metropolitan roads is for carrying passengers4 ,the traffic of the latter is similar to that usually carried on horse railroads1 and consists almost exclusively of passengers4 ,at present 7#ahgd7 there are only one or two metropolitan railroads in this country for carrying passengers which are operated by steam power4 ,it seems certain1 however1 that their use will soon become very general in all large cities4 ,their traffic will consist of many light trains run at short intervals and at comparatively slow speeds1 and therefore very light locomotives are required4 ,,question #dci4 ,what kinds of locomotives are used for suburban railroads8 ,answer4 ,the ordinary ,american eight-wheeled locomotive is used more than any other kind2 but a number of locomotives like that represented by fig4 #bbb have been built and are used for this traffic4 ,these have one pair of driving-wheels in front of the main pair and a ,bissell truck in front of the cylinder4 ,with this arrangement the driving-wheels bear a larger proportion of weight than they do if arranged on the ordinary ,american plan with a four-wheeled truck4 ,another plan is that shown in ,plate ,,xviii4 ,such engines1 as will be seen1 have a ,bissell truck at each end1 and therefore they run equally well either way4 ,in some cases the tanks of such engines are carried on the top and sides of the boiler4 ,when they are obliged to run only a short distance1 and a small supply of water is needed1 this arrangement answers very well2 but it is impossible to carry a large supply of water in this way without overloading the wheels of the locomotive1 and at the same time increasing the evils of a varying load on the driving-wheels4 ,illustration3 ,fig4 #bbb4 ,,light ,,passenger ,,and ,,freight ,,locomotive1 ,,by ,,the ,,grant ,,locomotive ,,works1 ,,paterson1 ,n4 ,j4 ,locomotives like that shown in ,plate ,,xiv are also used for suburban traffic4 ,as shown in the engraving they have a four-wheeled truck at one end and one with two wheels at the other1 so that it is thought that they can be run safely either way4 ,the four-wheeled truck carries the weight of the water and fuel4 ,the plan of engine represented by ,plate ,,xv is very well adapted for this kind of traffic4 ,excepting on curves with a very short radius it could be run in either direction at any required speed1 without encountering any other difficulty excepting the prejudices of those who run it4 ,as double-truck locomotives similar to that shown in ,plate ,,xvi can adjust themselves to any curve1 this objection could not be urged against their use4 ,,question #ddj4 ,what kinds of locomotives are used on metropolitan railroads8 ,answer4 ,for freight traffic ordinary switching locomotives like that represented in ,plate ,,iv are often employed4 ,in some cases these have the tanks on the locomotives4 ,it often happens1 though1 that such traffic must be conducted in the streets of a city1 and that the noise1 especially of the exhausting steam1 is thus liable to frighten horses and disturb the occupants4 ,it is1 then1 necessary either to condense the exhaust steam or render its escape noiseless1 which is done by allowing it to escape into the water-tanks4 ,street locomotives which have a condenser similar to the surface condensers used on marine engines are used on the ,hudson ,river ,railroad in ,new ,york4 ,the exhaust steam passes through these and then escapes into the tanks4 ,the latter are long and narrow1 so as to expose a great deal of surface to radiation1 and in this way cool the water which becomes heated by the steam4 ,the engines have four driving-wheels and vertical boilers4 ,the cylinders are connected to a crank shaft with a pinion on it1 which gears with another wheel of larger size on the driving-axle4 ,in this way the speed is reduced and great tractive power can be exerted4 ,the whole of the engine is enclosed so as to hide the machinery1 the sight of which is supposed to frighten horses4 ,the engines were designed and patented by ,mr4 ,a4 ,f4 ,smith1 formerly ,master ,mechanic of that road4 ,for roads in cities carrying passengers almost exclusively1 an entirely different class of locomotives is needed4 ,to suit passengers it is of course necessary to run a great many trains at very short intervals4 ,when this is done the trains are necessarily very light1 and therefore only light locomotives are needed4 ,plate ,,xix represents the locomotives employed on the ,greenwich ,street ,elevated ,railroad in ,new ,york4 ,these engines weigh only #aj1jjj lbs41 and the wheels are #cj in4 diameter and the cylinders #g #aj in4 ,the peculiarity in their construction consists in their having an intermediate shaft between the two pairs of driving-wheels4 ,this shaft has two cranks inside of the frames and two outside4 ,the cylinders are connected to the inside cranks1 and the coupling-rods to those on the outside4 ,the water is carried in a tank on top of the boiler4 ,the fuel is anthracite coal4 ,,part ,,xxiii4 ,,continuous ,,train ,,brakes4 ,,question #dda4 ,what are meant by automatic or continuous train brakes8 ,answer4 ,continuous train brakes are brakes which can be applied to all the cars of a train by the locomotive runner on the locomotive4 ,in some cases such brakes are arranged in such a way that they can also be applied from any car in the train1 or are made self-acting in case of an accident1 such as a car getting off the track or a train breaking in two4 ,,question #ddb4 ,what are the principal systems of brakes of this kind in use8 ,answer4 ,what is called1 after its inventor1 the ,westinghouse atmospheric brake is now used more than any other4 ,next to this1 ,smith's vacuum brake is used most4 ,besides these two1 ,creamer's1 ,ward's1 ,loughridge's and ,henderson's systems of brakes are used to a limited extent4 ,the two first are1 however1 the only ones which have come into sufficiently extensive use as yet to justify us in describing them here4 ,,question #ddc4 ,how does the ,westinghouse brake act and how is it constructed8 ,answer4 ,as its name indicates1 the medium employed for transmitting the power for operating the brakes is atmospheric air4 ,illustration3 ,fig4 #bbc4 ,scale in4 #a foot4 ,this is compressed to any required density by a steam pump which is located between the driving-wheels1 or in any other convenient place on the locomotive4 ,this pump is shown in section in fig4 #bbc and consists of two cylinders1 the upper one1 ,a1 the steam cylinder1 the piston of which is connected by its rod with the piston in the lower cylinder1 ,b4 ,this latter is operated by the steam piston1 and at each stroke a quantity of air1 equal to the space swept through by the lower piston1 is compressed and thus forced into a cylindrical reservoir1 which is usually placed under the foot-board of the locomotive1 in which it is stored for use at any time when the brakes are to be applied4 ,the air and steam cylinders are supplied with suitable valves for admitting and releasing the air and steam4 ,from this reservoir it is conducted back under the tender and cars by pipes1 which are connected together between the engine and tender and between the cars by ,india rubber hose4 ,two pieces of hose are attached to the engine and also to each end of the tender and cars1 so that in case one piece should break the others will act4 ,each of these pieces is united or coupled to the corresponding piece opposite to it by a peculiar coupling made for the purpose1 so that they can be quickly disconnected if the cars1 engine or tender are uncoupled4 ,under the tender and also under each car is a cylinder and piston4 ,the compressed air is conducted to this cylinder in front of the piston when the brakes are to be applied4 ,as the piston-rod is connected by a bell crank to the brake levers when the piston is forced out by the pressure of the air1 the brakes are at once applied to the wheels4 ,as the reservoir under the foot-board is connected by the pipes which have been described with the cylinders under each car and the tender1 by simply opening communication between the reservoir and the pipes1 the air at once rushes from the reservoir back through the whole length of the train1 and so rapid is its motion and quick its action that only a second or two intervenes between the opening of communication and the application of the brakes4 ,to relieve or 8let off0 the brakes it is only necessary to close the reservoir cock and open communication from the air-pipes to the external atmosphere1 when the compressed air in the brake cylinders will escape1 and the springs ordinarily used on car brakes will cause the pistons to resume their former positions4 ,for the purpose of opening the connection from the reservoir to the brake cylinder1 and closing this connection and opening one from the latter to the external air1 a single three-way cock is commonly used4 ,this is arranged at such a point as to be under the control of the engineer1 so that he can at pleasure turn on the compressed air with any degree of force1 instantaneously1 or slowly1 or with a varying power1 or by another turn of the cock let it off as freely1 still keeping it under the same complete control4 ,illustration3 ,fig4 #bbd4 ,scale #a inch #a foot4 ,,question #ddd4 ,how does the vacuum brake act and how is it constructed8 ,answer4 ,the power is applied to the brakes of the cars in this system by exhausting instead of compressing the air4 ,this is done by means of an ejector1 of which fig4 #bbd is a section4 ,this operates somewhat like an injector4 ,steam is admitted into the pipe ,b1 and escapes through the annular or circular opening a a4 ,the effect of this is to create what is called an 8induced current10 or to draw the air from the pipe ,c ,c1 which1 with the steam1 escapes at ,a4 ,this produces a partial vacuum in the pipe ,c1 which extends back under the cars4 ,the pipes under the cars are connected together by rubber hose1 which are prevented from collapsing by coils of wire inside4 ,under the tender and under each car are ,india rubber cylinders with cast iron ends1 one fastened to the car and the other movable4 ,the rubber cylinders can be extended or compressed somewhat like the bellows of an accordeon4 ,the rubber is supported by iron rings inside1 placed from #d to #f inches apart1 so as to prevent them from collapsing when the air is exhausted from them4 ,when this is done the pressure on the movable cast iron end draws it towards the fixed one1 and by attaching the former to the brake levers by a rod1 the force of the pressure on the head is communicated to the brakes4 ,the ejector is placed on top of the boiler1 and when the brakes are to be applied the locomotive runner opens a valve1 which admits steam into the ejector1 which instantly begins to produce a partial vacuum and thus apply the brakes4 ,when the pressure of the brakes is to be released1 the release valve1 ,d1 is opened1 which admits air into the pipe1 ,c1 through which it is conducted back to each of the ,india rubber cylinders1 and thus counteracts the pressure on the ends and releases the brakes4 ,both the atmospheric and the vacuum brakes have recently been applied to the driving-wheels of locomotives with very excellent results4 ,,part ,,xxiv4 ,,performance ,,and ,,cost ,,of ,,operating ,,locomotives4 ,,question #dde4 ,what is the cost of operating ordinary locomotives per mile run8 ,answer4 ,the average cost at the present time 7#ahgd7 is from #bj to #be cents per mile4#ajc #ajc ,deducting #aj per cent4 from this amount will give very nearly the gold value of the cost4 ,the figures given above represent the cost in the depreciated promises to pay of the ,united ,states ,government4 ,,question #ddf4 ,what items of cost are included in this1 and what proportion do they each bear to the total cost8 ,answer4 ,the items of cost and the percentage of each to the whole expense of operating locomotives1 and also to the total of all the expenses of operating locomotives are given in the following table3 ,percentage ,percentage of total ,approximate of total cost of all average cost of the operating cost per operating expenses of mile run4 locomotives4 railroads4 ---------------------------------------- ------------------ ,fuel #f4j cts4 #j4cj 4#jc ---------------------------------------- ------------------ ,oil and waste #j4d cts4 #j4jb 4#jjd ---------------------------------------- ------------------ ,wages of locomotive runners and firemen #f4j cts4 #j4cj 4#jf ---------------------------------------- ------------------ ,repairs of locomotives #g4j cts4 #j4ce 4#jg ---------------------------------------- ------------------ ,cleaning locomotives #j4f cts4 #j4jc 4#jjf ---------------------------------------- ------------------ ,total #bj4j cts4 #a4jj 4#bj ,from this table it will be seen that the locomotive expenses are #bj per cent4 of the whole cost of operating railroads4 ,this cost of course varies under different circumstances4 ,the above is probably somewhat lower than the average cost in this country4 ,,question #ddg4 ,how many miles do locomotives ordinarily run per ton of coal and per cord of wood8 ,answer4 ,this also varies greatly under different circumstances4 ,an average taken from the monthly reports of #eb different roads gives #ch miles run per ton of coal1 and an average from the reports of #af roads gives #dg miles run per cord of wood4 ,no deductions should1 however1 be made from this of the relative value of wood and coal for fuel1 because the trains which are run with wood for fuel are usually lighter than those hauled with coal-burning engines4 ,the above figures are the average results during the month of ,may1 #ahga1 of all the trains on the roads from whose locomotive reports it has been compiled4 ,the following report of experiments1 which were carefully made by the writer1 will give the performance of a locomotive when great care is taken to produce good results4 ,it should be stated1 however1 that the engine with which these experiments were made had been in service eighteen months1 without receiving thorough repairs1 and that the boiler at times primed badly1 so that the rate of evaporation of water per pound of coal is not a fair indication of the performance of the engine in that respect4 ,the coal used was known as ,brazil coal1 from ,indiana1 and in order to compare the performance of two engines only lumps of coal were used1 so as to leave no room for question regarding the relative amount of fine coal used by each engine4 ,the maximum grades on the road on which the experiments were made were #cj feet per mile1 and the total ascent from the lowest to the highest point on the road was #cgd feet4 ,,locomotive ,,experiments4 #ahgc4 #ahgc4 #ahgc4 ,date of experiment ,july #ba4 ,july #bh4 ,august #b4 ,number of miles run #ade #ade #ade ,number of cars hauled #da #ca #da ,total weight of cars1 lbs4 #a1dig1bdj #a1aai1fej #a1ejh1hfj ,total amount of coal burned1 lbs4 #h1fgf #e1ajb #g1bba ,total am'nt of water consumed1 lbs4 #fc1eca #de1gai #eb1fji ,water evaporated per lb4 of coal1 lbs4 #g4cb #h4jb #g4jd ,miles run per ton 7of #b1jjj lbs47 of coal #cc4d #ej4h #ch4h ,coal consumed per car per mile1 lbs4 #a4de #a4ac #a4ba ,average speed1 including stops1 miles #aa4a #ac #ac4h ,,question #ddh4 ,how can we determine the speed at which an engine is running8 ,answer4 ,in the absence of any special instruments for the purpose1 ,,by ,,counting ,,the ,,number ,,of ,,revolutions ,,of ,,the ,,driving-,,wheels ,,per ,,minute1 ,,then ,,multiplying ,,the ,,length ,,of ,,their ,,circumference ,,in ,,inches ,,by ,,the ,,number ,,of ,,their ,,revolutions ,,per ,,minute ,,and ,,the ,,product ,,by #fj1 ,,and ,,dividing ,,the ,,last ,,product ,,by #fc1cfj4 ,,the ,,quotient ,,will ,,be ,,the ,,speed ,,in ,,miles ,,per ,,hour4 ,thus1 supposing driving-wheels which are #fa in4 in diameter1 and whose circumference is therefore #aic4b in41 should make #afd revolutions per minute1 then #aic4b #afd #fj #fc1cfj #cj1 7nearly7 miles per hour4 ,,part ,,xxv4 ,,water-,,tanks ,,and ,,turn-,,tables4 ,,question #ddi4 ,how are locomotive tenders or tanks supplied with water8 ,illustration3 ,fig4 #bbe4 ,scale in4 #a foot4 ,answer4 ,at suitable points1 called water stations1 along the line of the road1 large tanks or reservoirs are located1 which are filled either from a natural stream which is higher than the tank and thus flows into the latter1 or else the water is pumped in1 either by hand or by horse1 wind1 water or steam power4 ,these tanks are usually1 when there is room for them1 located near the track1 as shown in fig4 #bbe1 so that the water can be conducted by a spout1 a1 direct from the tank to the man-hole of the tender4 ,communication to and from this spout is opened and closed by a valve1 b1 inside of the tank4 ,the spout is usually attached to the tank by a hinged joint1 so that it can be lowered to the tender and then raised up out of the way of the engine and train4 ,it is generally balanced by a counterweight1 suspended to one end of a rope1 which passes over a pulley and is fastened to the spout at the other end4 ,such tanks are now generally made of wooden staves like a tub or pail1 and supported on a heavy frame1 c c c1 made of wood1 as shown in the engraving1 or on stone or brick masonry4 ,illustration3 ,fig4 #bbf4 ,scale in4 #a foot4 ,when there is no room for the tank or reservoir near the track1 it is placed in any convenient position at some distance from it1 and the water is then conveyed by an underground pipe to the place where the locomotive must take water4 ,at the end of this pipe what is called a water-crane1 fig4 #bbf1 is located4 ,this consists of a vertical pipe1 ,a1 with a horizontal arm1 ,b1 which is made so as to swing around over the man-hole of the tender when the latter is to be filled with water4 ,in some cases the horizontal arm alone swings around1 but in others the vertical pipe turns with the horizontal one in a joint1 ,c1 underneath the surface of the ground4 ,the latter plan is thought to be preferable to the first1 as the pipe is less liable to freeze fast in the joint when the latter is underground than when it is exposed above4 ,a suitable valve1 ,d1 is also attached to the pipe below ground1 so that the stream of water can be turned off or on at pleasure by the wheel ,e4 ,,question #dej4 ,what considerations should determine the source from which a supply of water should be drawn8 ,answer4 ,the first must of course be its convenience to the point where the water is to be used2 but more attention should be given to the quality of the water than it ordinarily receives1 as the use of impure water1 or that which contains a considerable amount of mud or solid matter mixed with it1 or in suspension as it is called1 or has lime or other mineral substances chemically combined with it1 will very soon coat the inside of the boiler with a covering of scale1 which is a very bad conductor of heat1 and consequently the boiler is much less efficient and much more heat is wasted than if the heating surfaces were clear4 ,besides this loss of efficiency1 when boiler plates are covered with non-conducting scale1 they are much more liable to be injured by the action of the fire than when the water comes directly in contact with the metal of the plates4 ,some water1 too1 has a corroding effect on the metal of the boiler which is very destructive4 ,,question #dea4 ,how can the relative amount of incrustating substances in different kinds of water be determined8 ,answer4 ,the relative quantity of solid matter or mud which is held in suspension can be at least approximately determined by simply filling vessels1 say large clear glass bottles1 with different kinds of water and letting them stand for some time until the solid matter settles to the bottom4 ,an easy method of precipitating the lime and some other salts which are held in solution and which will not settle until they are converted into a solid form is the following3 ,dissolve in a goblet of pure water 7distilled or freshly caught rain water7 two or three teaspoonfuls of the oxalate of ammonia4 ,have equal quantities1 say a goblet-full of each of the waters to be tested1 ranged side by side and marked so as to be identified4 ,into each of these goblets stir equal quantities of the solution mentioned--about three teaspoonfuls will be enough--and let them stand for a day4 ,the lime and some other salts will be precipitated and fall to the bottom as a powder2 and the quantity of this precipitate in each glass will form a very good index of its relative injuriousness in the formation of scale4 ,when the oxalate of ammonia cannot easily be procured1 an experiment may be tried1 in the same way1 by dissolving common white soap1 or other pure soap1 in a goblet of pure water1 and then stirring into the glasses of water to be tested a few teaspoonfuls of this solution4 ,the comparative amount of lime in the water will be shown by the amount of coagulated matter which will be thrown down4#ajd #ajd ,correspondent of the ,railroad ,gazette4 ,,question #deb4 ,how are locomotives turned around on the track8 ,answer4 ,the most common means employed for that purpose is a turn-table1 fig4 #bbg4 ,this consists of two heavy beams made of wood1 cast or wrought iron1 placed side by side and resting on a pivot in the centre1 on which they turn4 ,they are placed in a circular pit below the level of the track1 so that when rails are laid in the ordinary way on top of the beams they will be exactly level with the track which leads up to the pit4 ,by turning the beams on the central pivot so that the rails will come exactly in line with the permanent track which leads up to the pit1 the locomotive can be run on the turn-table1 which is then revolved a half-revolution1 which of course reverses the position of the locomotive and brings it opposite the permanent track so that it can be run off from the table4 ,in order to prevent the beams from tipping down when the engine first runs on or off of the turn-table1 wheels are placed at their outer ends which run on a circular track and bear any inequality of weight that may be thrown on them if the locomotive is not equally balanced on the central pivot4 ,illustration3 ,fig4 #bbh4 ,scale in4 #a foot4 ,,question #dec4 ,how is the central pivot constructed8 ,illustration3 ,fig4 #bbg4 ,scale inch #a foot4 #ej-;,,foot ,,turn-,,table1 ,,by ,,william ,,sellers ,,co41 ,,philadelphia4 ,illustration3 ,fig4 #bbi4 ,answer4 ,it usually consists of a vertical post1 ,a1 shown in fig4 #bbh1 which is a transverse section through the centre of the turn-table1 the end of which rests on hard cast iron or steel bearings4 ,in some cases1 as shown in figs4 #bbg and #bbh1 which represent a turn-table built by ,william ,sellers ,co41 of ,philadelphia1 the weight rests on conical steel rollers1 m m1 which revolve in a circular path formed in the top plates4 ,sometimes turn-tables are fitted with gearing and cranks1 ,d1 fig4 #bbh2 but if they are made so that the whole weight rests on the centre1 and if they are of sufficient length so that an engine and tender can be moved on them sufficiently to be balanced over the centre1 gearing will not be needed2 but a simple lever fastened to the turn-table will be all that will be required to turn the table and the engine and tender on it4 ,the tables should be of such a diameter or length across the centre as will enable the class of engine in use on any road to be balanced4 ,with light engines the #ej-;feet table is large enough2 with the long1 heavy engine now used on the great trunk lines1 the engine and tender quite fill up the entire length of #ej feet1 leaving no margin for adjustment4 ,in such cases1 the #ed feet1 #ef feet1 or1 better1 the #fj feet1 should be employed4 ,these large tables are also made heavier in proportion4 ,the table should be of such a length that engines1 with tender either empty or full1 when run on the table can be so placed as to bring the centre of gravity immediately over the centre4 ,when so balanced1 one man can turn the loaded table with ease4 ,in setting up turn-tables it is necessary that the foundation at centre1 upon which the pivot rests1 should be of the most substantial character1 so as not to be liable to settle4 ,the circular track1 which may be made of light rails1 say #bh or #cj lbs4 to the yard1 should be level1 and the table should be so adjusted as to swing clear of the circular track when loaded4 ,the pit required is quite shallow near the edge and deepens towards the centre4 ,provision is made for covering the entire pit by a platform turning with the table1 but this should be avoided whenever possible1 as the best constructed cover does offer some resistance in turning4 ,even in roundhouses1 where a covered pit might be considered preferable as presenting a smooth floor for crossing in any direction1 it has been found advisable1 in view of the greatest ease in turning and the facility offered by the open pit for cleaning1 to dispense with the cover4 ,the centre upon which the table turns is constructed of the best cast steel1 and consists of conical rollers of steel between two steel plates grooved out to receive these rollers4 ,this part of the table must be kept clean and well oiled1 say with best sperm or lard oil and tallow of such a consistency as not to harden in cold weather4 ,the top cap at centre is held in place by a circle of bolts4 ,these bolts take the entire weight of the table and load2 by slacking off the bolts the table can be lowered on the wheels on the circular track and the cap lifted off to gain access to the plates and rollers4 ,these should be opened1 examined and cleaned at least once every three months4 ,under the cap and between it and the top of the centre box are segments of wood4 ,these can be altered in thickness to bring the table in proper adjustment4 ,if the centre foundation settles1 these segments should be thinned sufficiently to enable the table to be screwed up to a proper height4 ,with proper care such tables are practically indestructible4#aje #aje ,wm4 ,sellers ,co4 ,,question #ded4 ,is there any other method of turning locomotives8 ,answer4 ,yes2 what is called a ,y is sometimes used4 ,this consists of a system of tracks laid somewhat in the form of the letter ,y1 as shown in fig4 #bbi1 in which ,a ,b is the main track1 with two curves1 ,a ,c and ,b ,c1 laid as shown4 ,if now it is desired to turn a locomotive which is standing in the position of the dart ,a1 it is run on the curve ,a ,c to the position of the darts a and ,c4 ,it is then run backward from ,c on the curve ,c ,b1 as represented by the dart b1 and when it reaches the main track in the position of the dart ,b it is evident that its position will be reversed1 as is shown if we compare the direction of the dart ,a with that of ,b4 ,,part ,,xxvi4 ,,inspection ,,of ,,locomotives4 ,,question #dee4 ,what are the principal divisions of the work of operating or running a locomotive8 ,answer4 ,they are3 #a4 ,inspection and lubrication2 that is1 an examination of the parts to see that they are in good working order1 and the application of oil to the journals and other parts subjected to wear4 #b4 ,setting the engine in motion and starting the locomotive and train4 #c4 ,management while running4 #d4 ,stopping the engine and train4 #e4 ,laying up4 #f4 ,management in case of accident4 #g4 ,cleaning the engine4 ,,question #def4 ,when the locomotive is inspected1 what should be especially observed about the boiler8 ,answer4 ,in the first place1 all new boilers should be tested by pressure before being used1 and ,,all boilers1 whether new or old1 ,,should ,,be ,,tested ,,periodically4 ,the oftener the better4 ,the ways of applying the pressure test are3 #a1 the cold-water test1 that is1 by filling the boiler with cold water and then forcing in an additional quantity with a force-pump so as to raise the pressure to that at which it is intended to test the boiler2 #b1 the warm-water test1 by filling the boiler entirely full of cold water and then kindling a fire in the grate so as to warm this water4 ,as water expands about one twenty-fourth in rising from #fj to #bab degrees1 the rise in temperature will cause a corresponding increase in pressure2 #c1 by steam pressure4 ,if the latter method were not so commonly used1 it would seem the height of madness to test a boiler--which is neither more nor less than an attempt to explode it--in the shop where it is built or repaired1 and where the results of an explosion would be more disastrous and fatal than anywhere else1 in order to see whether it will explode when put into service on the line of the road4 ,the danger of explosion is also increased at such times by hammering and caulking at leaky rivets and joints4#ajf ,it would seem1 therefore1 very much more rational to test boilers first by hydraulic pressure4 ,for a first test this is preferable1 because cold water will leak through crevices which would be tight when the boiler is heated1 so that leaks can be more surely detected with cold than with warm or hot water4 ,it is1 however1 doubtless true that boilers are often strained much more by the unequal expansion of the different parts than by the actual pressure4 ,it is therefore thought that after the hydraulic test has been applied the second or warm-water test should be used4 ,this can be easily done1 as the boiler must be filled full of water for the first test4 ,when the boiler is subjected to the test pressure1 it should be carefully examined to see whether any indications of weakness are revealed4 ,any material change of form or any very irregular change of pressure is indicative of weakness4 ,the flat stayed surfaces should be carefully examined by applying a straight edge to them before and after they are subjected to pressure1 to see whether they change their form materially4 ,one of the greatest dangers and most common accidents to locomotive boilers1 as has been pointed out in a previous chapter1 is the breaking of stay-bolts1 to detect which1 a locomotive runner and master mechanic should exercise constant vigilance4 ,while the pressure is on1 the outside surface of the boiler should be thoroughly examined with slight blows of a hammer1 which will often reveal a flaw in the metal or a defect in workmanship4 ,after the hydraulic and warm-water tests have been applied1 the boiler should be emptied1 and the inside examined carefully to see whether any of the stays and braces have been broken or displaced by the test4 ,after this has been done1 and not until then1 should steam be generated in the boiler4 ,in making the latter test it would doubtless be more safe to employ a pressure somewhat lower than that employed with the cold and warm water4 ,there is great diversity of opinion regarding the maximum pressure which should be employed in testing boilers4 ,it is doubtless true that a weak boiler might be injured and thus made dangerous by subjecting it to a very severe pressure1 while without such a test it would have been safe4 ,recent experiments have indicated1 however1 that in most cases the ultimate strength of material is actually increased by subjecting it to a strain which even exceeds the elastic limit1 provided such a strain is imposed only a few times4 ,although no absolute rule can be given to govern all such cases1 it is thought that for the hydraulic and warm-water tests1 a pressure about #ej per cent4 greater and for the steam test #be per cent4 greater than the maximum working pressure should be employed4 #ajf ,wilson on ,boiler ,construction4 ,before old boilers are tested1 they should be very carefully examined1 both inside and outside1 to see whether they are injuriously corroded4 ,it is to be regretted that the insides of locomotive boilers are usually made so difficult of access that it is impossible to discover the extent and the effects of corrosion without the most careful examination4 ,this is not possible without getting inside of the boiler4 ,whenever this can be done1 a prudent locomotive runner should use the opportunity of inspecting the boiler of his engine himself1 and not depend upon the boiler-makers who are employed for that purpose4 ,he should remember that it is his life and not theirs which is exposed to danger by any weakness or defect in the construction of the boiler of the locomotive which he runs4 ,before starting the fire in a locomotive1 the fire-box should be carefully examined to see if there are any indications of leaks1 which will often reveal cracked plates1 defective stay-bolts or flues4 ,if the latter simply leak at the joints1 they can generally be made tight by caulking or the use of the tube expander4 ,this is easily done when the engine is cold1 but if not attended to may be very troublesome on the road4 ,leaks at other parts of the boiler should be examined1 as they may reveal dangerous fractures4 ,it is of the utmost importance1 both for safety and for economy of working1 that boilers should be kept clean1 that is1 free from mud and incrustation4 ,in some sections of the country1 especially in the ,western ,states1 this is the greatest evil against which locomotive runners and those having the care of locomotives must contend4 ,the cures which have been proposed are numberless1 but that which is now chiefly relied upon is1 first1 the use of the best water that can be procured1 and second1 frequent and thorough washing out of the boiler4 ,,question #deg4 ,what sort of examination should be given to the boiler attachments8 ,answer4 ,it should be observed whether the grate-bars or drop-doors of the grate are properly fastened1 and whether the ashes have been cleaned out of the ash-pan1 and also whether the fire is clean1 that is1 whether the grates are free from cinders or clinkers4 ,the height of water in the boiler should be observed by testing it with the gauge-cocks and by noticing it in the glass gauge1 if one of the latter is used4 ,it is also well to blow out the sediment and mud from the latter before starting1 and to see that the valves which admit steam and water to the glass are open4 ,they should1 however1 be opened only a very short distance1 so that only a small quantity of steam or hot water will escape in case the glass tube should be broken4 ,the injector1 if one is used1 should be tested to see that it is in working order1 and as soon as the engine starts out of the engine house both of the pumps should also be tested1 in order to see whether they are in good working condition4 ,the safety-valves should be raised1 so as to be sure that they are not rusted or otherwise fastened to their seats4 ,there is no part of a locomotive more liable to disorder than the steam gauge4 ,for this reason it should be frequently tested1 and whenever there is any indication of irregularity in its action it should be examined4 ,as the wire netting on the smoke-stack often has holes cut into it by the action of the sparks1 it should be frequently examined to see whether it is in good condition4 ,it is also liable to be 8gummed up10 especially if too much oil is used in lubricating the cylinders and valves4 ,as soon as holes are cut into the netting there is danger that the sparks which escape will set fire to the combustible material near the track1 and if the netting is gummed up the draft will be obstructed and the engine will not make steam4 ,the gummy matter can often be removed by building a wood fire on top of the netting4 ,in this way the oil in the gummy matter is burned up1 which leaves a dry material which can then1 at least to some extent1 be beaten out of the netting4 ,,question #deh4 ,how can it be known whether the pumps are working well8 ,answer4 ,their operation is indicated by the force of the stream which escapes from the pet-cock when it is open4 ,when the pump is in good condition the water begins to escape promptly in a strong stream as soon as the pump-plunger begins its inward stroke1 and continues to escape until the plunger completes its stroke4 ,if the pump is not in good condition1 this escaping stream is weak and is apt to continue during the outward stroke of the pump-plunger4 ,it is difficult to tell1 however1 when the engine is running slowly1 whether the pump will work well at higher speeds1 and therefore a locomotive runner should always test the condition of the pumps during the previous run4 ,,question #dei4 ,what should be noticed in connection with the throttle-valve8 ,answer4 ,as a failure of the throttle-valve to work may be the cause of a most serious accident1 it should be certain that it is in good working condition1 that all the bolts1 pins and screws and other accessories are in good working order4 ,it should also be known whether the throttle-valve is steam-tight4 ,this can be learned by observing whether steam escapes from the exhaust-pipes or cylinder-cocks when the latter are open1 the reverse lever in full gear1 and the throttle-valve closed4 ,if the throttle-valve leaks1 enough steam may accumulate in the cylinder1 when there is no one on the engine1 to start it1 and in this way cause a serious accident4 ,the throttle-lever should always he fastened with a set-screw or latch of some kind when the engine is standing still4 ,,question #dfj4 ,in inspecting the cylinders1 pistons1 guides and connecting-rods1 to what points should the attention be directed8 ,answer4 ,it should be known whether the piston packing is properly set out1 that is1 whether it is so tight that it will not 8blow through10 or leak steam from one end of the cylinder to the other1 which of course will waste a great deal of steam4 ,of the two evils1 it is1 however1 better to have piston-packing too loose than too tight1 because if it is too tight1 it is liable to cut or scratch the cylinders so as to make it necessary to rebore them1 and at the same time if the packing-rings are lined with ,babbitt metal1 the heat created by the intense pressure and friction will melt the metal4 ,in some cases the cylinders become heated to so high a temperature from this cause that the wood-lagging with which they are covered on the outside is burned4 ,the packing of the piston-rods should be steam-tight1 and it should be observed whether the rod and the pump-plunger are securely attached to the cross-head4 ,the utmost care must be exercised to keep the guides well oiled4 ,the oil cups on the guide-rods or cross-heads1 when they are placed on the latter1 must be kept clean1 so that the oil will flow freely1 and yet not too rapidly1 on the surfaces exposed to friction4 ,the same thing is true of the oil-cups on the connecting-rods4 ,attention should be given to the brass bearings of the connecting-rods to see that they are not so loose as to thump1 nor keyed so tight on the crank as to be liable to heat4 ,the latter can be easily known by moving the stub-end lengthwise of the journal4 ,they should never be so tight that they cannot be thus moved with the hand4 ,especial attention should be given to seeing that all the bolts and nuts on the connecting-rods are tight4 ,there are no parts of a locomotive which require more careful attention in order to keep them lubricated1 and thus prevent them from heating and being 8cut10 than the bearings on the crank-pins and the slides of the cross-head4 ,examination should be made to see that neither the piston-rods1 pump-plungers1 guides1 connecting-rods nor crank-pins are bent or sprung4 ,,question #dfa4 ,how can it be known whether the piston-packing is too loose or 8blows through80 ,answer4 ,it can usually be noticed in the sound of the exhaust1 which can be heard very distinctly on the foot-board when the furnace door is opened4 ,if the packing is not tight1 it produces a peculiar wheezing sound between and after each discharge of steam4 ,if the packing leaks1 it will also be indicated by the escape of steam from both the cylinder-cocks1 if they are open1 just after the crank passes the dead point4 ,this will usually show in which of the cylinders the packing is too loose4 ,the same thing will occur1 however1 if either or both of the main valves leak1 so that it is often hard to determine whether the 8blow0 is due to a leak from the valve or from the piston4 ,of course1 it may sometimes happen that both leak1 or that the piston on one side and the valve on the other leak1 so that often the diagnosis of the disease1 as the doctors say1 is extremely difficult4 ,careful observation and experience will1 however1 aid a locomotive runner in detecting such defects much more than any directions which can be given here4 ,,question #dfb4 ,what is meant by 8setting out packing10 and how should it be done8 ,answer4 8,setting out packing0 is simply expanding the rings when they get too loose4 ,with ordinary spring packing1 figs4 #if and #ig1 which is now generally used1 this is done by screwing up the nuts b1 b1 b1 which1 as was explained in answer to ,question #afi1 compresses the springs a1 a1 a1 and thus expands the rings ,a1 ,a4 ,in doing this1 as already stated1 great care must be exercised not to screw the nuts up too hard1 and it is always better to have the packing too loose than too tight4 ,care must also be taken to keep the piston-rod in the centre of the cylinder1 otherwise there will be undue pressure and wear on the stuffing-box4 ,after the nuts are screwed up1 the position of the piston-head should be tested with a pair of callipers4 ,this is done by placing one leg of the callipers against the side of the cylinder1 and setting them so that the other leg will just touch the edge of the projection ,e1 fig4 #if1 or the end of the piston-rod4 ,then by placing the callipers above and below1 and on each side of the piston1 it will appear whether it is too high or too low or too near either side2 then by loosening the nuts on one side and tightening them on the other it can be moved to a central position4 ,ordinarily this work is intrusted to persons who are employed for the purpose4 ,a young locomotive runner1 fireman or mechanic will1 however1 always do well to familiarize himself with such duties1 and1 if possible1 do it himself1 under the direction of those who are skilled in that kind of work4 ,,question #dfc4 ,if the stuffing-box of the piston-rod leaks1 what should be done8 ,answer4 ,if the packing in it is in good condition1 it can usually be made tight by simply screwing up the gland4 ,in doing this1 the nuts on the bolts should not be screwed up more than is necessary to make the packing steam-tight4 ,any greater pressure only increases the friction on the piston-rod unnecessarily4 ,in doing this1 the two bolts must be screwed up equally1 otherwise the gland will be 8canted10 that is1 inclined so as to 8bind0 or bear unequally and very hard against the piston-rod1 and thus be liable to cut or scratch it4 ,after packing has been in the stuffing-box a long time1 it becomes very hard and compact1 and sometimes partly charred4 ,then either it must be removed and new packing be put in1 or1 if in tolerably good condition1 it can often be made to work well by simply reversing it1 that is1 by putting that which was at the bottom of the stuffing-box on top and vice versa4 ,before packing is put into a stuffing-box1 the former should always be thoroughly oiled4 ,,question #dfd4 ,when the slides of the cross-heads wear1 how is the lost motion taken up8 ,answer4 ,when there are gibs on the cross-head1 the lost motion can be taken up by putting 8liners0 or 8shims10 that is1 thin pieces of metal1 between them and the cross-head1 so that they will fill up the space between the guide-bars4 ,when there are no gibs1 the guide-bars must be taken down1 and the blocks between them at each end must be reduced in thickness so as to bring the bars nearer together4 ,in doing this1 great care must be taken that the guides are accurately 8in line0 with the centre line or axis of the cylinder4 ,this work should never be intrusted to any excepting skilled workmen1 from whom those who are inexperienced should seek instruction4 ,,question #dfe4 ,when the brass bearings of the connecting-rods become too loose on their journals1 what should be done8 ,answer4 ,they must be taken down1 and the two surfaces in contact must be filed away so as to bring them closer together4 ,in doing this they must be filed square with the other surfaces1 otherwise they will not bear equally on the journals when they are keyed up4 ,before attaching them permanently to the rods1 they should be keyed on the journal in the strap alone1 so that it can be known by trial whether they move freely and yet are tight enough to prevent thumping on the journal4 ,when they are attached to the rod1 it is very important1 especially with coupling or parallel-rods1 that the correct length from centre to centre of the bearings be maintained4 ,it is much better to leave coupling-rods loose on their journals1 because1 if the bearings are keyed up tight1 the rods are sure to throw an enormous strain on the crank-pins1 as the distance between the centres of the axles is not always absolutely the same1 owing to the rise and fall of the axle-boxes in the jaws4 ,it is therefore always best to have a little play in the coupling-rods1 and it is safe to say that much more mischief is done by meddling with the coupling-rod brasses than by neglecting them4 ,,question #dff4 ,what part of the valve gear should receive attention when the engine is inspected8 ,answer4 ,all the bolts1 nuts and keys should be carefully examined to see that they are properly fastened4 ,the bolts and nuts in the eccentric straps are especially liable to become loose1 and as they are between the wheels1 and therefore not easy of access1 are often neglected4 ,the oil-holes should all be seen to be clear1 otherwise it will be impossible to keep the journals well oiled4 ,the eccentric straps and the link blocks are very liable to be imperfectly oiled1 and when the former become dry and cut1 they throw a great strain on the eccentric-rods1 which is liable to break them4 ,when this occurs the strap and the portion of the rod which is attached to it revolve with the eccentric1 and frequently a hole is thus knocked into the front of the fire-box1 which disables the engine4 ,the valve gear is1 with the exception1 perhaps1 of the pumps and injector1 the most delicate part of the locomotive1 and more liable to get out of order than any other1 and should therefore be watched with the greatest care4 ,,question #dfg4 ,how can it be known whether the main valves of a locomotive are tight8 ,answer4 ,as already indicated1 the symptoms which manifest themselves when a valve leaks are very similar to those which appear when the piston packing leaks4 ,if the valve is moved to its middle position and steam is admitted into the steam-chest1 and it then escapes from both cylinder-cocks1 it is apparent that the valve is not tight4 ,but the valve faces of locomotives usually wear concave1 because the valves are worked most about half-stroke1 so that they will often be tight when in the centre of the face1 but will leak at the ends of the full stroke4 ,this will become apparent by the peculiar wheezing sound1 already referred to1 when the engine is at work4 ,as has been explained1 it is1 however1 often very difficult to determine whether this sound is due to a leak at the pistons or the valves4 ,if the packing of the valve-stem leaks1 it can be remedied in the manner described for making that of the piston-rod tight4 ,,question #dfh4 ,to what points of the running gear should attention be directed during inspection8 ,answer4 ,all the wheels of the engine and tender should be carefully examined to see that they are sound4 ,a fracture in a driving-wheel is usually apparent if the wheel is carefully examined4 ,the condition of ordinary cast iron tender and truck-wheels is revealed on striking them with a hammer1 when if they are sound they will give out a peculiar clear ring2 whereas if they are fractured1 the sound produced by the blow of the hammer will be dead1 like that of a cracked bell4 ,the flanges of the wheels should also receive attention to see that they are not broken1 as such a fracture is not always revealed by the sound produced by a blow from a hammer4 ,the axles too should be examined to see that the wheels have not worked loose on the wheel-seat4 ,when this occurs it often becomes apparent by the oil from the axle-boxes working through between the hubs of the wheel and the axle4 ,this can be observed on the outside of the wheels when the bearings are inside1 and inside the wheels when the bearing is outside4 ,the springs should be examined to see that they are in good condition1 and the oil-holes in the boxes must be kept clear1 so that the oil can reach the bearings4 ,the tender boxes are kept oiled by packing them with cotton or woolen waste saturated with oil4 ,this should be taken out occasionally and renewed and the boxes cleaned4 ,the working of the driving-boxes up and down the jaws will in time wear them so that there will be some lost motion in the jaws4 ,this will be indicated by a thump when the cranks pass the dead point4 ,a similar thump will1 however1 be produced by lost motion in the boxes of the main connecting-rod1 so that it is difficult to determine1 without special examination1 the cause which produces the concussion4 ,it is therefore best when an engine works with a thump at each revolution for the runner to stand by the side of it where he can touch the connecting-rods and driving-wheels1 and then have the fireman open the throttle-valve so as to move the engine slowly4 ,if the lost motion is in the connecting-rods it can be felt by the jar as it passes the dead points4 ,the same is true of lost motion in the jaws1 which can be felt by touching the driving-wheels4 ,when the jaws become worn the lost motion can be taken up by moving up one or both of the wedges4 ,when this is done1 great care must be taken to keep the centres of the driving-axles the same distance apart on both sides of the engine1 and also to keep their centre lines square with the frames4 ,there should always be centre-punch marks placed on the frames or guide-yokes on each side of the engine in front of the main axle1 and at equal distances from its centres1 so that when the boxes or jaws become worn the position of the axle can be adjusted with a tram from these marks4 ,of course1 if the main axle is square1 it is easy to adjust the trailing axle from it with a tram4 ,if the axles are not square with the frames and parallel with each other1 the engine will run towards one side or the other of the track1 according to the inclination of the axles4 ,it sometimes happens that the bolts which hold up the wedges in the jaws are broken4 ,when this occurs the wedge drops down1 and of course the box has so much lost motion that it soon manifests itself in the working of the engine4 ,these bolts1 and also those which hold up the clamps on the frames at the bottom of the jaws1 should be examined when the engine is inspected1 so as to be sure they are in good condition4 ,the bolts and nuts about both the engine and tender trucks should be watched to see that none are lost or work loose4 ,the engine and tender should occasionally be lifted up from the centre plates of the truck1 and the latter be lubricated with tallow4 ,it often happens that these become dry1 so that they are difficult to turn when the weight rests on them1 and therefore they will not adjust themselves easily to the curves of the track4 ,,question #dfi4 ,what other parts of a locomotive should be examined before starting8 ,answer4 ,it should be certain that the brakes on the tender are in good working condition1 that is1 that the bolts1 nuts and keys are all secure1 the levers1 rods and chains properly connected1 and the shoes fastened and not too much worn4 ,if either an atmospheric or vacuum brake is used1 it should be tested before starting1 to see that the pump or ejector is in good working condition4 ,it is also well to apply the brakes to the train before starting1 so as to see whether the connections are in good condition and properly connected4 ,it is always best for the locomotive runner to examine the connections of the brake hose through the whole train himself1 to be sure that they are properly made4 ,the inside of the water-tank should also be examined occasionally1 to see whether it is clean1 and if not it should be thoroughly washed out4 ,the man-hole should always be covered before starting1 in order to prevent cinders and coal from falling in1 which are liable to obstruct the pump valves4 ,it is hardly necessary to say that it must always be certain before starting that there is enough water in the tank to feed the boiler until the next point is reached at which a supply can be obtained4 ,the sand-box must also be filled1 the bell rope in good condition1 and if running at night the reflector of the head-light must be polished and the lamp supplied with oil and the wick trimmed so as to burn brilliantly4 ,the locomotive runner must also see that the proper signals are displayed in front of his engine4 ,,question #dgj4 ,what tools1 etc41 should every locomotive runner on the road carry8 ,answer4 ,a coal shovel1 coal pick1 long-handled hoe#ajg and poker1 a pair of jacks1 either screw or hydraulic1 chains1 rope and twine to be used in case of accident1 a heavy pinch-bar for moving the engine1 a small crow-bar1 oil-cans with short and long spouts and another smaller one with spring bottom1 a steel and a copper hammer1 a cold and a cape chisel1 a hand-saw1 axe and hatchet1 one large and one small monkey-wrench and a full assortment of solid wrenches for the bolts and nuts of the engine1 cast iron plugs for plugging tubes1 with a bar for inserting them1 two sheet iron pails or buckets1 different colored lanterns and flags1 according to the colors used for signals on the line1 and a box with a half-dozen torpedoes4 #ajg ,these are of course not needed on wood-burning engines4 ,,question #dga4 ,what duplicate parts should be carried with the engine8 ,answer4 ,keys1 bolts and nuts for connecting-rods1 split-keys1 wedge bolts1 bolts for oil-cellars of driving and truck boxes1 driving and truck spring-hangers1 wooden blocks for fastening guides in case of accident1 blocks for driving-boxes and links1 a half-dozen -in4 bolts1 from six inches to two feet long1 to be used in case of accident1 two extra water-gauge glasses1 two glass head-light chimneys4 ,,question #dgb4 ,what should be observed in lubricating a locomotive or any other machinery8 ,answer4 ,the most important thing to observe is that the oil reaches the surface to be lubricated4 ,it is of much greater importance that the lubricant should reach the right place than that a large quantity should be used4 ,a few drops carefully introduced on a journal will do much more good than a large quantity poured on the part carelessly4 ,for this reason all oil-cups and oil-holes should be kept clean so as to form a free passage for the oil4 ,,part ,,xxvii4 ,,running ,,locomotives4 ,,question #dgc4 ,before starting the fire in a locomotive1 what must be observed8 ,answer4 ,it must always be noticed1 before kindling the fire1 whether the boiler has the requisite quantity of water in it2 that all cinders1 clinkers and ashes are removed from the grates and ash-pan2 that the grates and drop-door are properly fastened1 and that the throttle-valve is closed and the lever secured4 ,locomotive boilers are sometimes seriously injured by building a fire in them when there is no water in the boiler4 ,in filling a boiler it must be remembered1 however1 that when the water is heated it will expand1 and that when bubbles of steam are formed they will mix with the water and thus increase its volume1 so that after the water is heated its surface will be considerably higher than when it is cold4 ,,question #dgd4 ,how should the fire in a locomotive be started8 ,answer4 ,it should be started very slowly1 so as not to heat any one part suddenly4 ,probably the greatest strains which a locomotive boiler has to bear are those due to the unequal expansion and contraction of its different parts4 ,when the fire is started1 of course the parts exposed to it are heated first1 and consequently expand before the others4 ,now1 if the fire is kindled rapidly1 the heating surfaces will become very hot before the heat is communicated to the parts not exposed to the fire4 ,thus the tubes1 for example1 will be expanded so as to be considerably longer than the outside shell of the boiler1 and therefore there will be a severe strain on the tube-plates1 which will be communicated to the fire-box1 stay-bolts1 braces1 etc4 ,the inside plates of the fire-box will also become much hotter than those on the outside1 and as it is rigidly fastened to the bar to which both the inside and the outside shells are fastened at the bottom1 its expansion will all be upward1 which thus strains the stay-bolts in that direction4 ,as the motion due to this expansion is greatest near the top of the fire-box1 the top stay-bolts are of course strained the most1 and it is those in that position1 as has already been pointed out1 which are the most liable to break4 ,when steel plates are used the expansion or contraction often cracks them1 and sometimes1 hours after the fire is withdrawn from the fire-box1 the inside plates will crack with a report like that of a pistol4 ,it is therefore very important both to heat and cool a locomotive boiler very slowly1 and the fire should always be kindled several hours before the engine starts on its run4 ,,question #dge4 ,what should be done when the locomotive leaves the engine-house and before the train is started8 ,answer4 ,before leaving the engine-house the cylinder cocks should be opened1 so that all the water or steam which is condensed in warming the cylinders can escape4 ,before the engine is started from the engine-house the bell should be rung and time enough allowed for any workmen employed about the engine to get out of the way4 ,this rule must be scrupulously obeyed under all circumstances1 and a locomotive should never be started without first giving such a signal4 ,without it there is always danger that some one about the engine will be hurt or killed4 ,while running from the engine-house to the train the runner should observe very carefully the working of all the parts of his engine1 and as far as possible see that they are in good working condition4 ,the fireman should stay on the tender to handle the brake1 as may be necessary1 and should assist in coupling the tender to the first car of the train4 ,the junction with the train1 especially when it is a passenger train1 should be made very gently1 as otherwise passengers may be injured by the shock4 ,before starting the runner should see himself that the engine and tender are securely coupled together1 and the latter to the train1 that the frictional parts are properly lubricated1 as explained heretofore1 that the fire is in good condition and that the requisite quantity of steam has been generated4 ,if the steam is too low1 the blower is started1 which stimulates the fire4 ,,question #dgf4 ,when the train is ready1 how should the engine be started8 ,answer4 ,after the signal to start is given by the conductor1 the runner also gives a signal by either ringing the bell or blowing the whistle4 ,the latter should1 however1 be used1 especially at stations1 as little as possible1 on account of the risk of frightening horses and the shock which it produces on persons who are unaccustomed to hearing it1 or are suffering from any nervous disorder4 ,after giving the requisite signal1 the runner places the reverse-lever so that the valve will work either in full gear or very near it4 ,he then opens the throttle slowly and cautiously so as to start the train gradually4 ,if the train is a very heavy one1 it is best to back the engine so as just to 8take up the slack of the train10 that is1 to push the cars together so that there will be no space between them and thus compress the car draw-springs4 ,when the cars stand in this way1 those at the front end of the train are started one after another1 which makes the start easier than it would be if it were necessary to start them all at once4 ,if the throttle is opened too rapidly1 the driving-wheels are apt to slip1 but with a very heavy train1 even with the greatest care1 this is liable to occur4 ,if the train can not be started otherwise1 the rails must be sanded by opening the valves in the sand-box4 ,as little sand should be used as possible1 because the resistance of cars running on sanded rails is greater than on clean rails1 and thus the train is more difficult to draw after it reaches the rails to which sand has been applied4 ,thus the difficulty to be overcome may be increased by the means employed to overcome it4 ,while the train is slowly set in motion the fireman and runner must ascertain by watching whether the whole train moves together1 and that none of the couplings are broken in starting1 and also whether any signal is given to stop1 as is sometimes necessary after the train has started4 ,on leaving the station he should observe whether all the signals indicate that the track is clear and that the switches are set right1 and also look out for obstructions on the track4 ,the train should always be run slowly and cautiously until it has passed all the frogs1 switches and crossings of the station yard1 and not until then and when the runner has seen that everything is in order should he run at full speed4 ,as the engine gains in speed the reverse lever should be thrown back and nearer the centre of the quadrant or sector1 so as to cut off 8shorter40 ,,question #dgg4 ,after the engine is started1 how can it be run most economically8 ,answer4 ,the advantage of using steam expansively has already been explained in ,part ,v42 it is more economical to use steam of a high pressure which is done by keeping the throttle-valve wide open1 and then regulating the speed by cutting off shorter--that is1 expanding it more4 ,if the speed is reduced by partly closing the throttle-valve1 the steam is wire-drawn and1 as was shown in answer to ,question #ei1 it then produces much less useful effect than it would if it was admitted into the cylinder at full boiler pressure4 ,it is found1 however1 that in many cases if the steam is cut off very short the final pressure when it escapes is so low that it does not produce blast enough to stimulate the fire1 and therefore the boiler will not make enough steam4 ,this is more liable to occur with engines which have small than with those which have large boilers1 or when the boilers are in bad condition or the fuel is of poor quality4 ,when it does occur it is necessary to work steam during a longer portion of the stroke1 so as to increase the final pressure when it is exhausted and regulate the speed with the throttle-valve4 ,of course this is very wasteful1 but it is often the best which can be done and pull the train4 ,there is also another practical difficulty in using steam of a high pressure and running with the throttle wide open and regulating the speed with the reverse lever alone4 ,the link motion1 as has already been explained1 will not be effective in cutting off at a point below about one-quarter of the stroke4 ,now it often happens1 even when cutting off at that short point1 with light trains on a level or slightly descending grade1 that the speed will be too great if the throttle is wide open and with full steam pressure in the boiler4 ,when this is the case1 it is absolutely necessary to reduce the speed either by partly closing the throttle1 or reducing the pressure in the boiler4 ,undoubtedly if valve-gear for locomotives was so constructed that steam could be cut off effectively at a shorter point of the stroke1 it would result in increased economy in the use of steam4 ,the runner should aim to run at as nearly uniform speed as possible1 and in order to do so should divide the distance between stopping points and the time given for running it into as small divisions as he conveniently can1 so as to be able to tell as often as possible whether he is running too fast or too slow1 and thus travel over the shorter spaces in corresponding periods of time4 ,,question #dgh4 ,how should the boiler be fed8 ,answer4 ,the feeding of the boiler should if possible be continuous1 and the quantity of water pumped into it should be adjusted to the amount of work which the engine is doing4 ,ordinarily one pump is more than sufficient for feeding the boiler1 so that usually only the one on the right side of the engine1 where the runner stands1 is used4 ,the flow of the water is regulated by partly opening or closing the feed-cock4 ,the injector is commonly used only when the engine is standing still1 when the pumps will not feed4 ,in feeding the boiler it must be seen that the water is neither too high nor too low4 ,if it is too low there will be danger of overheating the crown-plates or even of an explosion2 if it is too high1 the steam space in the boiler is diminished unnecessarily1 and will cause the water to rise in the form of a spray1 and thus be carried into the cylinders with the steam1 or the boiler will prime or foam1 as it is called4 ,this water1 if it collects in the cylinder as already explained1 may by the concussion produced by the motion of the piston break the cylinder4 ,,question #dgi4 ,what is the cause of priming in a boiler8 ,answer4 ,it is often caused by the difference in temperature and pressure in the water below and the steam above4 ,thus1 if we have a boiler in which the water is heated to a temperature due to #ajj lbs4 effective pressure1 or #cch degrees1 and we then open the throttle-valve suddenly1 so as to relieve the pressure on top of the water1 there will at once be a rapid generation of steam in the water which will rush to fill the space from which the steam has been drawn4 ,this newly generated steam will be formed at the hottest part of the boiler first1 that is1 next to the heating surface4 ,it will therefore happen that as soon as the pressure is relieved1 bubbles of steam from all parts of the heating surface of the boiler will flow to the point at which the steam escapes4 ,the motion of these bubbles will be so rapid that large quantities of water will be carried with them4 ,the same thing will also occur if the heat of the water is increased very rapidly4 ,the water will then become hotter than the temperature due to the pressure of the steam above it1 and consequently there will be a rapid formation and escape of bubbles of steam from the water1 which will thus have the same effect as they would have if the steam pressure was reduced4 ,the amount of water carried up with the steam is increased if the escape of the latter is obstructed in any way1 owing to imperfect circulation of water in the boiler1 or by floating impurities1 such as oil1 on the surface4 ,when this condition of things exists1 the ebullition is1 as it were1 convulsive1 and the water is thus carried up with the steam when it escapes4 ,priming is also probably due in some measure to the flow of steam over the surface of the water to the point of outflow1#ajh carrying particles of water with it just as a high wind will1 when blowing over the crests of the waves of the sea4 #ajh ,wilson on ,steam ,boilers4 ,when steam is drawn1 as it usually is in locomotives1 from the top of the dome to which the safety-valves are attached1 the tendency to prime is very much increased when they are blowing off1 so that some engineers advocate the use of two domes1 from both of which the supply of steam is sometimes drawn1 and in other cases the safety-valves are mounted on one1 and the steam-pipe is placed in another dome4 ,whenever the safety-valves begin blowing off steam1 the pressure in the boiler should be reduced as soon as possible1 not only because when they are blowing off it tends to produce priming1 but because the steam which escapes from them is wasted4 ,the pressure can be most economically reduced either by increasing the amount of water which is fed into the boiler or by opening the heater cocks and allowing the steam to escape into the tank and thus warm the water4 ,if the boiler is too full1 the former method cannot be employed1 and in heating the water in the tank the runner must be careful not to get it too hot1 because in that case neither the pumps nor the injectors will work satisfactorily1 and the paint on the tenders is also liable to be blistered and destroyed by the heat4 ,by feeling the tank with the hand it can soon be discovered whether the water is too hot4 ,if the steam pressure cannot be reduced in any other way1 the furnace door must be partly opened4 ,the use of muddy water will also sometimes cause a boiler to prime4 ,it is probable that priming is sometimes due to the formation of foam on the surface of the water1 and therefore all priming is often called foaming2 whereas it is thought that often a boiler will prime when the water does not foam4 ,more accurate information regarding the priming of boilers is1 however1 much needed1 as many of the phenomena have thus far not been satisfactorily explained4 ,the principal causes of priming in ordinary practice are1 however1 undoubtedly owing to defective circulation1 too little steam room1 impure water1 or too much water in the boiler4 ,,question #dhj4 ,how can it be known whether an engine is priming1 and what should be done to prevent it8 ,answer4 ,the priming of a boiler can be known by the white appearance of the steam which escapes from the smoke-stack and the cylinder cocks4 ,dry steam always has a bluish color4 ,when an engine primes or works water into the cylinders1 it is usually indicated by a peculiar dead sound of the exhaust1 which from this cause loses its distinctly defined and sharp sound4 ,this can be observed best when the furnace door is opened4 ,it is also indicated by the discharge from the gauge-cock1 as the water which then escapes from the lower cocks is mixed with steam1 or1 as runners say1 is not 8solid10 and the steam from the upper cocks is not clear1 but mixed with water4 ,to use a phrase employed by practical men1 the priming or foaming of the boiler may be known by the 8flutter0 of the gauge-cocks4 ,as soon as there are any indications of priming1 foaming1 or that water is working into the cylinders1 the cylinder cocks should be opened at once1 otherwise the cylinders1 cylinder heads or pistons may be broken4 ,the throttle-valve should be either partly or entirely closed4 ,when the latter is done the foaming will in most cases cease for the time1 so that the runner can tell how much solid water there is in the boiler4 ,if he finds that the boiler has too much water in it8 it is best to shut off the pumps1 and in many cases the blow-off cock is opened4 ,the latter is1 however1 attended with some danger1 because if any obstruction should get into the blow-off cock1 or it should stick fast1 so that it could not be closed1 all the water would escape from the boiler1 and with a heavy fire in the fire-box there would be great danger of overheating1 and thus injuring the boiler or of 8burning0 it1 as it is ordinarily termed4 ,a much better method of affording relief in such cases is to place what is called a surface-cock in the back end of the fire-box1 about half way between the upper and lower gauge-cocks4 ,with such a cock1 the water can be blown off from the surface instead of from the bottom4 ,as foaming or priming is often caused by oil1 or other floating impurities on the surface1 they can be blown out of the boiler with this arrangement1 whereas1 if the water escapes from the bottom of the boiler1 the floating impurities will always remain after it is blown off4 ,a perforated pipe1 which extends for some distance along the surface of the water inside the boiler1 is sometimes attached to the surface-cock1 so that the water which is blown off will be drawn from a number of points along the surface4 ,if the steam is rising rapidly when foaming begins1 it will be well to cool the boiler off by opening the furnace door part way4 ,this means of relief should1 however1 be used as little as possible1 because there is always danger of causing the tubes or other parts of the boiler to leak1 by either heating or cooling suddenly or rapidly4 ,if the engine primes when there is but little water in the boiler1 and at a time when the steam is rising rapidly1 it may sometimes be remedied by increasing the amount of feed-water1 and thus partly cooling the water inside4 ,the use of pure water1 careful firing so as to keep the steam pressure regular1 feeding the boiler so that the level of the water will be nearly uniform1 and then starting the engine carefully1 that is1 opening the throttle-valve gradually1 are the most effective means in practice of preventing a locomotive boiler from priming4 ,,question #dha4 ,what is the economical effect of priming on the consumption of fuel in locomotives8 ,answer4 ,it causes a great waste of heat1 first by the escape of that contained in the hot water which passes through the cylinders and which does no work1 and second1 when steam is mixed with a great deal of water1 it will not flow either to or from the cylinders as quickly or easily as dry steam will4 ,consequently the initial pressure on the piston1 if the engine is running even moderately fast1 and is cutting off short1 will not be so great as it would be if dry steam was used4 ,wet steam is also more difficult to exhaust from the cylinder than that which is dry1 and therefore the back pressure on the piston is greater when the boiler primes than when dry steam alone is used4 ,,question #dhb4 ,when running on the open road1 what should the locomotive runner observe8 ,answer4 ,either he or the fireman should constantly watch the track in front of them1 and also observe1 from time to time1 whether the train of cars1 especially if it is a long one which he is handling1 is in good condition4 ,,he ,,must ,,observe ,,every ,,signal ,,scrupulously1 ,,and ,,should ,,never ,,pass ,,one ,,until ,,he ,,is ,,sure ,,that ,,he ,,is ,,authorized ,,to ,,do ,,so4 ,the well-known maxim1 8be sure you are right2 then go ahead10 should be changed for locomotive runners to1 ,,don',t ,,go ,,ahead ,,until ,,you ,,are ,,sure ,,you ,,are ,,right1 ,,and ,,when ,,in ,,doubt ,,always ,,choose ,,the ,,side ,,of ,,safety4 ,in running through curves1 the speed of the train should always be moderated in proportion to the sharpness of the curve1 and before reaching it4 ,in running through curves1 the tendency of the train is to continue in a straight line1 and there is thus danger of running off the track4 ,the higher the speed1 of course1 the greater is the resistance which is required to prevent the train from running in a straight line1 and consequently the greater is the strain which is thrown on the flanges of the wheels and on the rails and axles4 ,in running through curves1 it is also impossible1 usually1 to see further than a short distance ahead1 and therefore1 if the train is running very fast1 it cannot be stopped in time1 should there be any obstruction or danger on the track4 ,,question #dhc4 ,what precautions should be observed in running over steep grades8 ,answer4 ,on approaching an ascending grade the runner should see that the fire is in good condition1 and as much coal should be put on it as can be burned to advantage4 ,he should also fill the boiler as full of water as he safely can1 without danger of priming1 and should heat this water as hot as possible without blowing off steam at the safety-valves4 ,the object of this is to have a supply of water already heated before reaching the grade4 ,if1 as often happens with a heavy train1 the boiler will not make as much steam as the engine consumes1 if there is a large supply of hot water in the boiler it can be used as a reserve1 should it be necessary to do so1 without danger of injury to the boiler4 ,if there was so little water in the boiler that it would be dangerous to allow it to get lower1 then it would be necessary to feed cold water as rapidly as the hot water escaped in the form of steam4 ,it is often impossible to heat all this cold water as fast as it is pumped into the boiler1 without reducing the steam pressure until there is then not sufficient power to pull the train4 ,if1 however1 there is a supply of hot water in the boiler1 at the critical point on the grade1 where the engine is most liable to fail1 the pump can be partly shut off1 and thus less water will be pumped into the boiler1 and the steam pressure be maintained without danger4 ,undoubtedly it is better to feed locomotive boilers uniformly1 if that is possible1 but it often happens that a reserve supply of hot water in the boiler enables an engine to pull a train up the most difficult place1 whereas1 without such a supply1 the locomotive would stick fast4 ,as the capacity of locomotives is rated on nearly all roads by the number of cars they can 8pull up the hill10 of course whatever aids them at the critical point increases their capacity4 ,it is this fact which gives engines with large boilers so much advantage over those with small ones4 ,in running up steep grades1 allowance should always be made for the effect of the inclination of the track upon the position of the water surface in the boiler1 and also the fact that as soon as the throttle-valve is closed1 and steam shut off1 the surface of the water will be considerably lower than when the engine was working hard4 ,on a grade of #ej feet to a mile1 the front end of the tubes of an ordinary locomotive would be about #a inches higher than the back end of the crown-sheet4 ,if1 then1 on working hard up such a grade1 it is succeeded by another of equal descent1 the front ends of the tubes would be #a inches lower than they were while coming up1 so that if the back end of the crown-sheet was covered with #a inches of water just before reaching the top1 it would be exposed to the fire as soon as the engine reached the descent4 ,this exposure would be dangerous1 because not only would the water be #a inches lower over the crown-sheet1 but it would fall considerably more when the throttle-valve was closed4 ,these considerations will show the danger of running the water too low while ascending steep grades4 ,in pulling trains up steep grades1 especial caution should be exercised to prevent any of the cars from breaking loose from the train1 because such an accident may cause great disaster4 ,as soon as the engine reaches the top of the grade1 the fireman should oil the main valves1 because it can only be done when steam is shut off1 as the oil will not run into the steam-chest when there is a pressure of steam in it2 and as the valves are always subjected to the severest wear while pulling up a steep grade1 the valves and valve-faces are apt to become dry4 ,as saturated steam to some extent prevents valves from cutting1 it is not so important that they be lubricated while the engine is working with steam1 but as soon as steam is shut off they should be oiled1 otherwise there is danger of their being injured by their friction on the valve-seats4 ,in running down grades1 the runner has the greatest possible cause for using every precaution1 because not only is the train much more difficult to control1 but usually frequent sharp curves prevent a view of the track for any considerable distance ahead4 ,he should1 therefore1 watch the track in front of him with the greatest vigilance1 so as to be ready to give the requisite signals to the brakemen to apply the brakes1 or1 if the engine and train are provided with continuous brakes1 to apply the latter1 or even reverse his engine1 in case of danger4 ,,question #dhd4 ,how should an engine be run past those stations where the train does not stop8 ,answer4 ,the speed of the train should be slackened in passing stations1 especially if a clear view of the track and switch signals can not be obtained at some distance before reaching the station4 ,there is always a possibility that the switches may be turned wrong1 or that there may be some obstruction on the track at stations1 so that some caution should be exercised in running past them4 ,the proper signal1 either by the whistle#aji or the bell1 should be given on approaching stations1 and also at all common road crossings4 #aji ,the methods of giving signals vary so much on different roads that no general direction that will suit all cases can be given4 ,,question #dhe4 ,what must be done on approaching a draw-bridge or a crossing of another railroad at the same level8 ,answer4 ,in many of the ,states it is provided by law that all trains must come to a dead stop before crossing a draw-bridge or another railroad at the same level4 ,whether such a law exists or not1 the rule should always be observed4 ,after coming to a stop1 the train should under no circumstances be started until the signal has been given to start the train by the signal-man at the bridge or crossing4 ,a runner should never assume that the signal has been given1 nor take another person's word for it1 but should see and know it himself4 ,in some conditions of the weather and with the light falling on a signal in certain directions1 it is sometimes difficult to determine its color or form4 ,if there is any doubt about it1 the testimony of another person should always be sought4 ,there is good reason for believing that color-blindness1 that is1 an incapacity for distinguishing one color from another1 is a much more common infirmity than is usually supposed4 ,it is certain1 too1 that people who ordinarily distinguish colors very accurately are subject to color-blindness in certain conditions of health1 and that it is sometimes the result of overwork or great weariness2 and a case is recorded of a person who was always color-blind after a debauch4 ,there are1 therefore1 good reasons why a locomotive runner should not always place too implicit confidence in what he 8sees with his own eyes10 but if he has any doubt1 he should take the 8benefit of the doubt10 which should always lead him to take the side of safety4 ,,question #dhf4 ,how should the engine and train be managed in running into a station8 ,answer4 ,first of all when running into a station when the train stops1 the speed must be checked so that the train will not enter with very great momentum4 ,therefore1 at a distance varying from one to three-quarters of a mile1 according to the nature of the grades and track1 the steam should be shut off1 so that the speed will be reduced so much that the train under any circumstances will be under full control4 ,it is always better to enter a station at too low a speed than to run in too fast1 because if it is necessary1 more steam can always be admitted to the cylinders to increase the speed before coming to a stop2 whereas it is not so easy to stop the train if it is running too fast1 and it becomes necessary to check it before entering the station4 ,this will sometimes be necessary1 because it may readily happen through negligence or accident at stations that in switching cars one or more may be left standing wholly or partly on the track1 which the arriving train must run over1 in which case a collision with its terrible consequences may be unavoidable4 ,when a train is equipped with continuous brakes1 the control which they usually give to a locomotive runner over the train is so great that he is apt to approach stations1 crossings or draw-bridges at a high rate of speed1 and rely on such brakes to stop the train4 ,this practice is always attended with great danger1 because if it was found1 on getting near to the station1 crossing or draw-bridge1 that the track was not clear1 and that it was obstructed by a car or train1 or the draw was open1 if the runner should attempt to apply the brakes and from some cause they should fail to work1 as sometimes occurs1 then a collision or other disaster would be inevitable1 because it would be impossible to stop the train with the ordinary hand brakes4 ,for this reason a locomotive runner should always approach such places cautiously and with his train under sufficient control1 so that if he finds there is danger ahead he can stop the train with the ordinary means1 or at the worst by reversing the engine4 ,continuous brakes should always1 excepting in cases of imminent danger1 be applied gradually1 so as not to check the cars with a jerk or too suddenly4 ,the practice of opening the cock which admits air to atmospheric brakes suddenly1 and then turning it back again as quickly1 is almost sure to produce disagreeable and dangerous shocks to the cars4 ,the cock should be opened gradually1 so as to check the cars slowly at first4 ,,question #dhg4 ,what must be attended to when running a locomotive at night8 ,answer4 ,as soon as it begins to grow dark1 the head-light must be lighted and properly trimmed1 and the proper lamp signals placed in front of the engine1 if the rules of the road require the display of such signals4 ,a lamp should always be placed in the cab1 so as to throw its light on the steam-gauge1 but not into the runner's face1 because he is unable to see distant signals so well if his eyes are exposed to the glare of a light near him4 ,at night1 as objects which are passed can not be seen distinctly1 it is more difficult to tell the speed at which an engine is running than it is in the day time4 ,a runner should therefore consult his watch frequently1 and by counting the revolutions of the wheels1 which he can do by the sound of the pump valve or other part of the machinery1 he can tell from the rule given in the answer to ,question #dch the speed at which the locomotive is running4 ,from this rule a table can easily be constructed for an engine with any size of driving-wheels1 showing the speed for any given number of revolutions per minute4 ,it will be a good exercise for a young locomotive runner to construct such a table1 which will be found very convenient for reference if placed in a conspicuous place in the cab4 ,,question #dhh4 ,what must be attended to in very cold weather8 ,answer4 ,great care must be exercised to prevent the water in the pumps1 pipes and in the tender from freezing4 ,if it does it will be almost certain to break the pump or burst the pipes4 ,to avoid this the heater cocks must be opened so as to keep the water in the tender warm4 ,in excessively cold weather the engine should be run with greater caution than at other times1 as iron is then more brittle1 and also more liable to break1 owing to the frozen condition and consequent solidity of the track4 ,,question #dhi4 ,in running a locomotive in severe snow or rain-storms1 what should be observed8 ,answer4 ,whenever it snows the pilot or cow catcher should be covered with boards1 or1 better still1 with sheet iron1 so as to act like a snow plow4 ,brooms made of steel wire should be placed in front of the front wheels of the engine1 so as to sweep the snow from the rails4 ,the front damper on the ash-pan should be kept closed so as to exclude the snow from the ash-pan1 which would soon fill it up1 and in this way obstruct the draft4 ,if the fall of snow is very heavy or it blows into drifts1 the train must of necessity run very slowly1 and even if a part of the track is clear of snow1 it is unsafe to run fast on it1 as there would be danger of throwing the engine off the rails if it should run into a heavy drift at a high speed4 ,in severe rain storms bridges1 culverts and such portions of the track as are liable to be washed away should be approached cautiously1 especially at night4 ,in both snow and rain-storms1 and also in fogs1 great caution is required1 owing to the difficulty of seeing signals4 ,,question #dij4 ,what is meant by a reserve engine or 8helper80 ,answer4 ,a reserve engine is a locomotive which is not employed in hauling a regular train1 but is kept as a 8reserve0 to go to the help of an engine which may be compelled to stop on account of an accident of any kind1 or to assist engines in moving trains up heavy grades1 or is used in clearing away a wrecked train1 rebuilding bridges or other structures4 ,,question #dia4 ,what must be observed in running a reserve engine8 ,answer4 ,as no special arrangements are usually made in preparing time-tables#aaj for the running of reserve1 or as they are usually called by railroad men1 8wild0 engines1 it may very probably happen that it will be called upon to assist other engines when the road is not clear1 and therefore its runner must constantly be on the look-out for signals to stop1 which are often given suddenly4 ,he must switch off with special caution in order to be sure to keep out of the way of regular trains running in the opposite direction on the same track4 ,when he reaches the train or place where the assistance of the reserve engine is needed1 he must approach it slowly and carefully1 in order to avoid a violent shock4 ,on the return from the assisted train1 he incurs the same danger1 and must pay close attention to any signal to stop made to him by any opposite train on the same track1 and also on his part warn such trains by the proper signals4 #aaj ,a time-table is a table which gives the time when each train shall arrive at the stations it passes1 the stations at which it shall stop1 and all the regulations by which it shall be run4 ,when a train is run with two engines1 both in front of it1 the forward one always takes the management of the train4 ,the runner of the hind engine must be guided by the signals of the runner of the forward engine4 ,in starting1 the forward engine must be set in motion first and then the one behind it4 ,in stopping1 the steam must be shut off first in the hind engine4 ,likewise in decreasing the speed during the trip1 the hind engine must first regulate the flow of steam4 ,if these precautions are not observed the forward engine may easily be thrown from the track by the faster motion of the hind one4 ,when a train is assisted by a 8helper0 placed behind the train1 and therefore pushing it1 the forward engine must likewise be set in motion first1 and steam should be let on in the hind engine only after a signal has been given by the runner of the head engine4 ,during the run both engines must move with the same speed4#aaa #aaa ,katechismus der ,einrichtung und des ,betriebes der ,locomotive1 by ,georg ,kosak4 ,,question #dib4 ,how should switching engines be managed8 ,answer4 ,in pushing and switching the freight cars in the station-yard1 they should be moved carefully and severe shocks must be avoided1 as the cars1 the goods with which they are loaded and the persons employed about them may be injured by violent concussions4 ,the runner must also follow the instructions of his superior strictly and cheerfully1 and should examine patiently and observe with discretion the suggestions of employes who are not his superiors4 ,in this service it is also of special importance that the runner give a distinct signal with the whistle or bell before every movement of his engine1 in order to warn in time those who at such times often stand on the track in the way of the engine or cars1 or the persons engaged in loading1 cleaning or repairing the cars1 and thus give them time to get out of the way4#aab #aab ,georg ,kosak4 ,,question #dic4 ,in firing a locomotive1 what are the most important ends to be attained8 ,answer4 ,that which is of first and chief importance is to make steam enough1 so that the locomotive can pull its train and 8make time0#aac2 second1 it must make the requisite quantity of steam with the least consumption of coal1 and third1 with the least production of smoke1 although the latter1 independent of the economy of combustion1 is considered of importance only with passenger trains4 ,what is frequently lost sight of in considering this subject is the fact that with all locomotives it often happens that it is a matter of extreme difficulty to make enough steam to do the work required of the engines4 ,when a freight train is struggling up a grade with a heavy train1 or an express engine is obliged to make time under similar conditions1 it often depends entirely upon the quantity of steam which can be generated in the boiler in a given time whether the engine will fail or not4 ,in firing1 therefore1 the most important end to be aimed at is often simply to produce the largest amount of steam possible in a given time1 even at the sacrifice of economy or by producing any quantity of smoke4 ,any means of economizing fuel or of smoke prevention1 which reduces the steam-producing capacity of boilers1 is therefore quite sure to be abandoned in time4 #aac ,the term make time means to run at the speed indicated on the time-table4 ,,question #did4 ,how can a boiler be made to produce the largest quantity of steam in a given time8 ,answer4 ,by burning the greatest quantity of fuel possible on the grate in that time4 ,this can be done by keeping the grates free from clinkers and the ash-pan from ashes1 and then distributing the coal evenly over the grates in a layer six to twelve inches thick4 ,the thickness of the layer which will give the best results will1 however1 vary with the quality of the fuel1 and must be determined by experience4 ,if the layer is too thick1 not enough air will pass through it to burn the coal4 ,if it is too thin1 then so much air will pass through that the temperature in the fire will be reduced4 ,the rapidity of combustion will also be promoted by breaking up the coal into lumps the size of a man's fist or smaller4 ,if fine coal is used it should be wet1 otherwise it will be carried into the flues by the blast before it is burned or caked or even reaches the grate4 ,experience will indicate the amount of air which can advantageously be admitted above the fire in order to secure the maximum production of steam4 ,the best size of the exhaust nozzles and the position of the petticoat pipe must also be determined by experience4 ,it will usually be found1 however1 that if enough air is admitted above the fire to prevent smoke1 it will reduce the maximum amount of steam which can be generated in a given time4 ,the fire should also be fed regularly and with comparatively small quantities of fuel at a time1 although if the feeding is too frequent there is more loss from the cooling effect which results from the frequent opening of the furnace door than is gained from the regularity of the firing4 ,in this1 too1 a fireman must consult experience to guide him4 ,,question #die4 ,how can a locomotive be fired with the least consumption of coal8 ,answer4 ,two systems of firing are practiced in this country1 one known as the 8banking system0 and the other the 8spreading system40 ,when the banking system is employed1 the coal is piled up at the back part of the fire-box1 as shown in fig4 #bah1 and slopes down towards the front of the grate1 where the layer of coal is comparatively thin and in an active state of incandescence4 ,the heap of coal behind is gradually coked by the heat in the fire-box and the gases are thus expelled4 ,openings in the furnace door admit air which mingles with the escaping gases1 which then pass over the bright fire in front1 and are thus supposed to be consumed4 ,when the 8bank0 of coal behind becomes thoroughly coked1 it is pushed forward on the bright fire and fresh coal is again put on behind to be coked4 ,this system of firing is practiced on some roads with good results1 but it is doubtful whether it could be used successfully with coal which cakes and clinkers badly4 ,the spreading system is most commonly employed in the ,western ,states1 where the coal contains a great deal of clinker4 ,when this is practiced1 the coal is spread evenly over the whole of the grate in a thin layer1 and its success and economy depend upon the regularity and evenness with which this layer of coal is maintained and the fire fed4 ,the thickness of the coal must be adapted to the working of the engine4 ,when it is working lightly1 the layer of coal should be thin1 but when the engine is pulling hard the layer of coal must be thicker1 otherwise the violent blast may lift the coal off the grates4 ,the success of this system1 as was explained in answer to ,question #chh1 depends upon the manner in which the thickness of the fire is regulated1 on the admission of the proper amount of air above the fire1 and on the frequency with which the fire is supplied with coal4 ,when this system of firing is employed not more than two shovels-full of coal should be put into the fire-box at once1 and if the engine is not working hard1 one or even less will be sufficient4 ,the firemen must1 however1 determine by experience the thickness of fire1 amount of air which should be admitted and the frequency of firing which will give the best results in practice4 ,doubtless these will vary with different kinds of fuel and the construction of engines4 ,usually the greatest obstacle in the way of producing good results is the fact that firemen would rather 8take things easy0 than exercise that diligence and observation which will alone insure success in any occupation4 ,,question #dif4 ,how can smoke be most effectually prevented8 ,answer4 ,the means of preventing smoke were very fully explained in answer to ,questions #cgi and #chh4 ,it may be said briefly that this can be done only by properly regulating the supply of air which is admitted to the fire4 ,the means of doing this have already been explained4 ,,question #dig4 ,what method of firing is employed when anthracite coal is used8 ,answer4 ,the spreading system alone is then used4 ,,question #dih4 ,how may the rules which firemen should observe when bituminous coal is used be briefly stated8 ,answer4 #a4 ,keep the grate1 ash-pan and tubes clean4 #b4 ,break the coal into small lumps4 #c4 ,fire often and in small quantities4 #d4 ,keep the furnace door open as little as possible4 #e4 ,consult the steam gauge frequently1 and maintain a uniform steam pressure1 and if necessary to reduce the pressure do it by closing the ash-pan dampers rather than by opening the furnace door4 ,,question #dii4 ,on arriving at a station where a train stops longer than a few minutes1 what should the locomotive runner and fireman attend to8 ,answer4 ,the runner should examine thoroughly all the parts of his engine1 as has been heretofore explained4 ,he should especially examine all the journals and wearing surfaces to see whether they are hot4 ,this he can discover by feeling them4 ,if any of them have become very much heated1 they must be cooled by throwing cold water on them1 and then thoroughly oiled4 ,in oiling a hot journal mineral oil should never be used1 as it is easily evaporated by the heat and then takes fire4 ,animal oil should therefore always be used on a hot bearing4 ,the working parts should be thoroughly lubricated1 as already explained4 ,the fireman should examine the tank and see whether it is necessary to take in a fresh supply of water4 ,he should then examine the grates and ash-pan1 and clean the cinders and clinkers from the former1 and the ashes from the latter4 ,neglecting to clean the ash-pan may result in melting and destroying the grate-bars1 and by obstructing the admission of air to the grates the ashes prevent the combustion from being as complete as it would be otherwise4 ,with some kinds of fuel it is necessary to clean the tubes frequently1 which must often be done at stations where the train stops4 ,during the stop1 as thorough an inspection of the engine should be made by the runner and fireman as the time will permit2 but any unnecessary waste of time must be avoided1 and the firing should be so managed that nothing need be done about it during the halt at the station4 ,on starting again the same precautions should be exercised as on making the first start4 ,,question #ejj4 ,after reaching the end of its run1 how should an engine be cleaned and repaired8 ,answer4 ,before reaching the last station the firing should be so managed that there will be as little fire as possible remaining in the fire-box at the end of the run4 ,after the arrival the engine should be run over a pit which is usually provided for the purpose1 and the fire should be raked out of the fire-box by dropping the drop-door if there is one to the grate1 or turning the grate-bars edgewise1 or withdrawing one or more of them if it is necessary to do so4 ,in this way the fire will fall into the ash-pan1 from which it can easily be raked4 ,after all the fire is withdrawn the dampers and furnace door should be closed so as not to allow the cold air to cool the fire-box and tubes too rapidly4 ,in order to keep the boiler clean1 that is as free as possible from sand1 sediment or incrustation1 it is necessary to blow it out frequently if the water which is used contains much solid or incrustating matter4 ,with 8bad water0 the boiler should be blown out as often as possible4 ,on some roads this is done after each trip4 ,in blowing a boiler out1 the blow-off cocks must be left open1 and after all the water has escaped the engine should be left to stand until it is cooled off4 ,if there is any considerable accumulation of mud or sediment the hand-holes at the bottom of the fire-box and the cover to the mud-drum should be taken off1 and as much of the mud removed as can be scraped out through those apertures4 ,a hose pipe attached to the hose of a force pump should then be inserted through these same openings1 and a strong stream of water forced into the boiler4 ,by this means much of the loose mud and scale will be washed out4 ,the oftener this is repeated of course the cleaner can a boiler be kept4 ,if a large amount of incrustation or mud has accumulated about the tubes1 some or all of them must be taken out1 so as to be able to remove the dirt4 ,after an engine is blown out1 under no circumstances excepting absolute necessity should it be filled with cold water until it is entirely cooled off4 ,it should be remembered that any sudden change of temperature in a boiler subjects it to very great strains and incurs the danger of cracking the fire-box plates1 or causing the tubes to leak4 ,the tender should also be cleaned of the mud which settles in it from time to time1 but it is not necessary to do this as often as it is to clean the boiler4 ,all the plates and flues should have the soot which sticks to them thoroughly cleaned off4 ,although the cleaning of the boiler and the grates is usually committed to a special set of men1 yet the locomotive runner should examine them personally to see that it is properly done4 ,he should pay attention to the condition of the grate1 and see whether it is level and smooth4 ,as soon as one or more of the bars are bent crooked1 they usually burn out4 ,if one of the bars is burnt out the fire falls through the hole that it leaves into the ash-pan1 and then the fire under the grate will heat it red hot1 and finally may melt every bar4 ,every grate-bar which is only a little damaged or bent must therefore be removed as quickly as possible and replaced with a new one4 ,as soon as the engine is run into the engine-house1 all superfluous grease which has escaped from the wearing surfaces and the dust or mud which adheres to the engine should be wiped off with cotton waste or rags4 ,this is usually done by men employed for the purpose4 ,while they are doing this1 they should examine every part thoroughly and observe whether it is in good condition1 and if any defects are found they should be reported to the proper person whose business it is to have them repaired4 ,as the faithfulness and skill of a fireman are often estimated by the good or bad condition of his engine1 he should1 if for no other reason1 take pains to keep it clean and everything in as good condition as possible4 ,if the engine is taken to pieces in order to be thoroughly repaired1 the runner1 if he does not help to do this1 should watch carefully the taking it apart and the putting it together again1 as in this way he can become thoroughly familiar with the construction of the machine he runs4 ,,question #eja4 ,what precaution must be taken to prevent the water in a locomotive from freezing1 if it is laid up8 ,answer4 ,in very cold weather1 if engines are laid up for any considerable time1 no water must be left in the tender1 boiler or any of the pipes4 ,if1 however1 the engine must be soon used1 and it is impracticable to let the water out of the boiler and tender1 then1 if exposed to the cold1 a light fire must be kept in the boiler sufficient to make steam enough to warm the water in the tender4 ,the water should1 however1 be drawn out of the pumps and the feed and supply pipes4 ,this can be done by opening the pet-cocks1 and closing the tender valves and uncoupling the hose1 which will allow the water in the supply pipes to run out4 ,by running the engine a few revolutions the pumps will then be emptied4 ,the pipes and the pumps can also be prevented from freezing without uncoupling the hose if the tender valves are closed and the pet-cocks opened1 and steam is then admitted into the supply pipes by the heater-cocks4 ,this forces part of the water which is in the pumps out of the pet-cocks and warms the rest4 ,this1 however1 requires constant watchfulness to prevent freezing1 and in excessively cold weather1 if the engine must lay up for any considerable time1 it is always best to empty the pumps and pipes4 ,,part ,,xxviii4 ,,accidents ,,to ,,locomotives4 ,,question #ejb4 ,what are the most serious accidents which may happen in running a locomotive8 ,answer4 ,the most serious accidents are3 #a4 ,collision of two trains approaching each other4 #b4 ,collision of a moving with a standing train4 #c4 ,collision of trains at the crossing of two railroads4 #d4 ,running a train into the opening left by an open draw-bridge4 #e4 ,escape of an engine without any one on it4 #f4 ,running off the track4 #g4 ,explosion of the boiler4 #h4 ,bursting or rather collapse of a flue4 #i4 ,blowing out of a bolt1 stud or rivet from the boiler4 #aj4 ,failure of the feed-pumps1 injector or check-valve4 #aa4 ,breaking or bursting of a cylinder1 cylinder-head1 steam-chest1 or steam-pipe4 #ab4 ,breaking or getting loose of the piston or cross-head or bending of the piston-rod4 #ac4 ,breaking or bending of a connecting-rod or crank-pin4 #ad4 ,breaking of a tire1 wheel or axle4 #ae4 ,breaking of a spring1 spring-hanger or equalizer4 #af4 ,breaking of a frame4 #ag4 ,breaking or getting loose of a part of the valve-gear4 #ah4 ,failure of the throttle-valve4 #ai4 ,breaking of a coupling4 ,,question #ejc4 ,what should be done to prevent a collision when two trains are approaching each other8 ,answer4 ,the obvious thing to do is to stop the trains as soon as possible4 ,this is done by applying the brakes at once with all their power1 and then reversing the engine1 although it is best not to do the latter until the train is somewhat checked1 as there is always danger of bursting the cylinder or breaking the cylinder-heads1 piston or connections if an engine is reversed suddenly at a high speed4 ,of course the higher the speed1 the greater is the danger of injury from this cause1 and therefore it is best1 if there is time1 first to check the speed of the train before reversing the engine4 ,when the engine is reversed1 the sand-valves should be opened so as to increase the adhesion of the wheels1 so that when their motion is reversed they may check the speed of the train as soon as possible4 ,on perceiving danger ahead the order of procedure should be as follows3 #a4 ,shut the throttle-valve4 #b4 ,if the train is equipped with hand brakes alone1 blow the danger signal for their application1 or if the train has a continuous brake1 apply it with its full force4 #c4 ,reverse the engine and open the throttle and the sand valves4 #d4 ,if a collision is inevitable1 shut the throttle-valve before the engines meet1 because if it is left open1 after the collision and when the speed of the train is checked1 the engine1 if not disabled1 will by its own power crush through the wreck and thus do additional damage4 ,,question #ejd4 ,what should be done if a standing train should see another train approach it and there should be danger of a collision8 ,answer4 ,the locomotive runner of the standing train should start his engine in the same direction as the approaching train is running1 as quickly as possible1 because the shock of the collision will be very much lessened if both trains are moving in the same direction compared with what it would be if one was standing still4 ,,question #eje4 ,what should be done to avoid a collision at a railroad crossing8 ,answer4 ,as was explained in answer to ,question #dhe1 trains should always come to a dead stop before crossing another railroad on the same level4 ,if1 however1 through any means danger of such a collision should be incurred1 then evidently the one train should be stopped and the other moved out of the way as soon as possible4 ,,question #ejf4 ,how can an accident by running into the opening at a draw-bridge be avoided8 ,answer4 ,first by ,,always coming to a dead stop before reaching it1 and second by not starting again until it is absolutely certain that the draw is closed4 ,of course if a locomotive runner of an approaching train finds a draw open1 the only thing he can do is to stop as soon as possible4 ,,question #ejg4 ,what measures should be taken to prevent locomotives from escaping without a responsible person on them8 ,answer4 ,in the first place when a locomotive is left standing the throttle-valve should always be closed and fastened1 the cylinder cocks should also be opened so that if any steam leaks into the cylinders it will not accumulate there1 but will escape1 and the reverse lever should be placed in the centre of the sector1 so that if by any accident the throttle should be opened the engine will not start4 ,,question #ejh4 ,if a locomotive should escape1 what should be done1 and how may it be captured8 ,answer4 ,the first thing to be done is to telegraph to the stations towards which the escaped engine is running1 either to keep the track clear1 or1 if there is a train approaching1 to open a switch and thus let the engine run off the track4 ,an escaped engine may be captured by a swifter engine following it1 but this is always attended with great danger1 as the first engine may leave the track or become wrecked4 ,a safer plan is to telegraph ahead of the escaped engine and have an engine placed in a position where the track can be seen for a long distance in the direction in which the runaway is expected4 ,as soon as the latter comes in sight1 the waiting engine should start in the same direction1 so that when they get near to each other they will both be running in the same direction and at nearly the same speed4 ,by regulating the speed of the front engine1 the following one may be allowed to come up to it quite gently1 and then a man can easily climb from the one engine to the other1 and thus both be stopped4 ,,question #eji4 ,what should be done in case an engine gets off the track8 ,answer4 ,the first thing to do is to close the throttle-valve and 8signal for brakes10#aad or apply the continuous brakes if the train is equipped with them1 and then reverse the engine4 ,if its position after it stops is much inclined1 it is generally necessary to draw the fire to prevent injury to the heating-surface1 a part of which is then usually exposed to the steam1 and therefore not covered with water4 #aad ,this expression means1 among railroad men1 to signal to brakemen by blowing the whistle to have them apply the brakes4 ,,question #eaj4 ,how is a locomotive replaced on the track in case it gets off8 ,answer4 ,it is impossible to give any directions for replacing locomotives on the track which will meet the great variety of circumstances which occur in practice4 ,if the engine has not run far from the rails1 it can usually be run on again by placing blocks of wood under the wheels and thus running them up to their proper position1 but if the engine falls on its side or runs down an embankment1 it is usually necessary to send for the appliances which are now provided on nearly all roads for removing wrecks and replacing engines on the track4 ,these appliances are generally stored in what is called a wrecking or tool car1 which is placed at a convenient point on the road1 from which it can be sent to any place where its services are likely to be needed4 ,such cars are generally provided with ropes1 jack-screws1 chains1 crowbars1 levers1 etc41 to be used in such cases1 and generally a special set of men is sent with the wrecking car to direct and assist in replacing engines and cars on the track4 ,it would lead us too far to describe all the methods of doing this employed under various circumstances2 and as such work seldom forms part of the duties of a locomotive runner1 a complete description would be out of place here4 ,,question #eaa4 ,after an accident which disables the engine1 what is the first thing to do8 ,answer4 ,the first thing to do is always to 8protect the train20 that is1 to send out signal men in each direction to stop approaching trains2 otherwise they might run into the wrecked train1 and thus cause a double accident4 ,,question #eab4 ,what is the chief cause of boiler explosions8 ,answer4 ,the cause of all boiler explosions1 as happily expressed by a prominent ,american engineer1#aae is ,,that ,,the ,,pressure ,,inside ,,the ,,boiler ,,is ,,greater ,,than ,,the ,,strength ,,of ,,the ,,material ,,outside ,,to ,,resist ,,that ,,pressure4 ,this may occur in two ways3 first1 and most frequently with locomotives1 from insufficient strength of the boiler to bear the ordinary working pressure2 and second1 from the gradual increase of heat and pressure until the latter is greater than the boiler was calculated to bear4 #aae ,see ,fifth ,annual ,report of the ,american ,master ,mechanics' ,association1 page #aif4 ,insufficient strength may be due3 #a1 to defects of the original design1 owing to the ignorance of the strains to which the material of the boiler will be exposed1 and its power of resistance2 #b1 to defective workmanship and material1 which can usually be discovered by careful inspection2 #c1 to the reduction of the original strength of the boiler by ordinary wear and tear or neglect1 which can also usually be discovered by careful inspection4 ,the first two causes have been fully discussed in the part relating to boiler construction1 and the last under the head of inspection of locomotives4 ,over-pressure is nearly always due to some defect of the safety-valve1 or to the fact that it is overloaded4 ,this latter often occurs when safety-valves are set by a defective steam gauge1 which indicates too little pressure4 ,over-pressure may also occur by letting an engine stand alone with a large fire in its fire-box and possibly with the blower turned on4 ,a boiler may1 by suddenly opening the throttle-valve1 undoubtedly be subjected to very severe strain that may possibly be sufficient to cause its destruction1 even though it had sufficient strength to bear the ordinary pressure at which the safety-valve blows off4 ,suddenly opening or closing the throttle-valve may produce a violent rush of steam and water against the part of the boiler whence the steam is drawn4 ,the percussion of the water and steam in such cases has been known to shake the whole boiler1 and to lift the safety-valve momentarily right off its seat4#aaf ,the weakest parts of a locomotive are the two sides where the barrel joins the outside fire-box4 ,many boilers1 especially those with a high wagon-top1 have flat spaces at this point1 which it is impossible to stay properly4 ,it is at this point1 too1 that the expansion and contraction of the tubes and the outside shell exert their greatest strains1 and it will therefore be found1 generally1 that the seams at this point begin to leak before any others1 and for these reasons it is believed that all the seams which join the outside shell of the fire-box to the barrel should be double-riveted4 #aaf ,wilson on ,boiler ,construction4 ,the practice of ascribing steam-boiler explosions to obscure causes has been productive of much mischief1 as it engenders a carelessness on the part of those having charge of them1 who have been led to believe that no amount of care will avail against the mysterious agents at work within the boiler4 ,explosions are also1 in the absence of other convenient reasons1 very generally attributed to shortness of water4 ,this is often nothing more than a convenient method of shifting the responsibility from the builder or owner of the locomotive to the runner or fireman1 who1 if not killed by the explosion1 in many cases might just as well be1 so far as his ability to defend himself is concerned4#aag #aag ,wilson on ,boiler ,construction4 ,,question #eac4 ,what should a locomotive runner and fireman do to avoid and prevent explosions8 ,answer4 #a4 ,the height of the water in the boiler should always be maintained so as to cover the heating surfaces4 #b4 ,the boiler should be kept as clean1 that is1 as free from scale1 mud and other impurities1 as possible4 #c4 ,it should never be subjected to strains from sudden heating or cooling4 #d4 ,the steam-gauge and safety-valves should be examined and tested frequently1 to be sure they are in order2 and #e1 they should examine every part of the boiler which is accessible1 but especially the stay-bolts1 to see that there is no fracture of any part or any injurious corrosion or other dangerous defect4 ,,question #ead4 ,what should be done in case of the bursting or collapse of a tube8 ,answer4 ,as soon as possible after it occurs1 the runner must stop the train1 and close first the end of the flue in the fire-box1 and then that in the smoke-box1 by driving in iron plugs1 which are usually provided for the purpose4 ,these plugs are attached to the end of a bar1 with which they are inserted into the tubes4 ,if the escape of water and steam from the tube is so great as to make it difficult to see the end of the tube1 the steam may sometimes be drawn up the chimney by starting the blower4 ,if1 however1 the escape is so great as to make it impossible to insert the plug1 then the steam pressure must be reduced by running with both pumps on1 or by starting the injector2 or it may be necessary to draw the fire and cool off the engine4 ,when a flue collapses1 the front end of which is behind the steam or petticoat pipes1 it is usually necessary to cool off the engine before a plug can be inserted1 especially if any considerable amount of water and steam escape from it4 ,while driving in the plug1 the runner and fireman should always keep themselves in such positions that the plug can not hit them in case it is blown out by the steam4 ,if the engine is not supplied with iron flue-plugs1 a wooden plug can be cut of the proper size and driven in4 ,this can be attached to the bar referred to and inserted2 but if no such bar is carried with the engine1 the wooden plug can be made on the end of a long pole and then cut nearly off4 ,it is then inserted into the flue and driven in and broken off4 ,it will be found that such plugs will burn off even with the end of the flue1 but will not burn entirely out4 ,,question #eae4 ,what should be done in case a bolt1 stud or rivet blows out of the boiler and thus allows the steam or hot water to escape8 ,answer4 ,if it is accessible1 cut a plug on the end of a long pole and drive it in in the same way as described above4 ,this will avoid the necessity of cooling off the engine2 but in some cases it will be found that a plug can not be inserted or driven in without drawing the fire and cooling off the boiler4 ,,question #eaf4 ,in case it is found necessary to draw the fire and cool off the boiler1 and if so much water has escaped as to uncover the crown plate1 what must be done8 ,answer4 ,if the leak has been stopped or the fault remedied1 one of the safety-valves should be taken off and water poured into the boiler with pails or buckets through the opening left by the removal of the safety-valve until the crown sheet is covered4 ,the fire may then be kindled again and the engine complete its journey4 ,when bituminous coal is used for fuel1 the necessity for drawing the fire in case of accident may often be avoided by completely covering or 8banking0 the fire with fine coal which has been wet1 and closing the dampers and opening the furnace door4 ,in this way the fire may be smothered and the boiler cooled without putting the fire out1 so that after the defect is remedied it will not be necessary to rekindle it4 ,,question #eag4 ,what must be done in case of the failure of one or both of the feed pumps or of the injector or check-valve8 ,answer4 ,if one of the pumps fails the other one may be used1 but the defect or obstruction to the first should be remedied as soon as possible1 because the second may also fail4 ,it will then be necessary to depend upon the injector alone1 if there is one1 for feeding the boiler4 ,only after all the appliances for feeding the boiler have failed and the water is so low as to be in danger of exposing the crown sheet1 should the fire be drawn or banked1 and the runner should then at once give the proper signals for warning and the protection of his train1 and if he is unable to repair the pumps or injector1 he must send for aid to the nearest accessible point4 ,,question #eah4 ,in case a pump fails1 how should it be examined in order to discover the defect8 ,answer4 ,as explained in the answer to ,question #deh1 the working of a pump is usually indicated by the stream which escapes from the pet-cock4 ,if1 when this is opened1 steam and water escape1 it is an indication that the check-valve is not working properly4 ,when this occurs hot water will escape if the pet-cock is opened when the engine is standing still1 but the pump may still feed the boiler if the upper or pressure-valve works properly4 ,when the check-valve does not work as it should1 it is also indicated by the heating of the feed-pipe1 owing to the escape of hot water from the boiler through the check-valve when the pet-cock is opened4 ,if1 when the plunger is drawn out of the pump1 air is sucked in through the open pet-cock1 then the upper or pressure-valve of the pump does not work1 but the working of the pump may still be secured by the working of the check-valve2 but if the pump1 air-chamber and feed-pipe then get filled with air1 the plunger may compress this air at each stroke1 and as it can then follow the plunger during its outward stroke1 the latter will not suck water1 but will simply compress the air during the inward stroke1 which will then expand during the outward stroke4 ,this will be indicated by the escape of air from the pet-cock when the plunger is moving inward1 and the suction of air when the plunger is moving outward4 ,this can be known by holding the hand in front of the pet-cock4 ,usually1 however1 the air is mixed with water so that the stream which escapes from the pet-cock is broken or irregular4 ,if air escapes from the pet-cock during the inward stroke of the plunger1 but none is sucked in during the outward stroke1 it shows that there is a leak somewhere in the pump or pipes1 and that it is pumping air instead of water4 ,the leak may be in the stuffing-box of the plunger1 the joints of the pump or pipes1 in the hose or their connections with the supply-pipe or tender4 ,if neither air nor water escapes from the pet-cock during the inward stroke of the pump plunger1 or1 if the stream of water at that time is weak1 then it indicates that the suction or lower valve of the pump is not working properly4 ,the same thing will occur if the pipe1 pump or tender-valve is obstructed4 ,if there is a cock1 as there always should be1 just above the suction-valve1 it will aid us very much to discover the fault when the pump will not work4 ,if1 when this cock is opened1 cold water escapes from it1 the fault is in the suction-valve2 if hot water1 then it is the pressure and check-valves which are leaky1 obstructed or broken1 and consequently the hot water from the boiler leaks back into the pump4 ,in the absence of such a cock1 the fault can often be discovered by feeling the pump barrel with the hand4 ,if the pump can not be made to work1 and the fault is found to be in the lower valve1 it must be taken out and examined2 or if the fault is in the pipes1 it can usually be easily remedied4 ,if the pipes are burst with only a small fracture1 it can usually be remedied by covering the aperture with canvas or rubber and wrapping twine around it tightly4 ,the upper valve of a pump must1 however1 never be taken down without first being sure that the check-valve is tight1 because if it is not1 the person will be likely to be scalded in taking the pump apart4 ,directions for managing an injector1 and also for taking care of pumps in cold weather1 have already been given in the answers to ,questions #adb and #dhh4 ,,question #eai4 ,what should be done in case of the breaking or bursting of a cylinder or cylinder-head8 ,answer4 ,the main connecting rod must be taken down on that side of the engine4 ,the piston should then be moved to the front or back end of the cylinder and wooden blocks be placed between the guides so as to fill up the space between the cross-head and the end of the guide-bars1 and thus prevent the cross-head and piston from moving4 ,the valve stem should then be disconnected from the rocker1 and the valve moved to the middle of the valve face1 so as to cover up both steam-ports4 ,it must then be fastened in that position by screwing up one of the bolts of the stuffing-box of the valve stem1 so as to make the gland bind against the valve stem4 ,the train should then be run cautiously to the next station with the use of one cylinder4 ,if the engine is not able to haul the train with one cylinder1 then it should be uncoupled from the train and run to the first telegraph station or other point where the aid of a helping engine can be obtained or telegraphed for4 ,in the meanwhile the train must be protected by the proper signals4 ,should the engine continue its journey with one cylinder1 it must be started1 if it should happen to be standing at the dead point1 by pushing or by means of crow-bars4 ,in so doing1 however1 the bars should not be put between the spokes of the wheels1 as they may easily be caught in the wheels when the engine starts1 and in this way the spokes be broken or the persons who are using the crow-bars be badly hurt4 ,,question #ebj4 ,what must be done in case a steam-chest or steam-pipe is broken8 ,answer4 ,if a steam-chest is broken a block of wood should be bolted over the mouth of the steam passage1 so as to prevent the escape of the steam from the steam-pipe on that side4 ,it will sometimes require considerable ingenuity to devise means of fastening such a block or blocks of wood so as to cover the mouth of the steam passage4 ,as cylinders are now usually made1 the blocks can be fastened by cutting them to the proper form and size1 and then placing a thick block on top1 and bolting the steam-chest cover down on top of it4 ,if the cover is broken1 a part of it may be used or a piece of plank with a few holes bored into it be employed instead4 ,in some cases a piece of board can be bolted over the end of the steam-pipe4 ,when the latter is broken1 it should be taken down and a piece of board or plank bolted over the opening of the -pipe to which the steam-pipe was attached4 ,the engine can then be run with one cylinder as before1 although usually in such cases it is not necessary to disconnect any other parts than the valve stem4 ,,question #eba4 ,what must be done if a piston1 cross-head1 connecting-rod or crank-pin is broken or bent8 ,answer4 ,if the piston1 cross-head or main connecting-rod is broken1 the same course must be pursued as when a cylinder is broken4 ,if a coupling-rod or a crank-pin of a trailing-wheel is broken1 then it is necessary to take down both the coupling-rods1 but not to disconnect the main connecting-rods or their attachments1 unless they are injured4 ,,question #ebb4 ,if one coupling-rod is broken or taken down1 why must the other be taken down also8 ,answer4 ,because if only one rod is used there is then nothing to help the cranks of the trailing wheels past the dead-points1 so that in starting1 or if they are moving slowly when they reach these points1 they are quite as likely to revolve in one direction as the other4 ,if they happen to turn in the reverse direction to that in which the wheels to which they are coupled are moving1 then the crank-pins of one or the other pair of wheels are very liable to be broken or bent4 ,,question #ebc4 ,what must be done if a driving-wheel tire or driving-axle breaks8 ,answer4 ,if a tire on a main driving-wheel or the wheel itself breaks1 the driving-box of the broken wheel or tire should be held up by putting a wooden block under the box4 ,an ordinary ,american engine can then be run on three driving-wheels1 but it must be run with the utmost caution4 ,if the engine has more than four driving-wheels there is usually less difficulty in running it1 if one of the main wheels is injured1 than if there are only four4 ,but it is almost impossible to give directions which will be applicable to all the accidents of this kind that may occur to different kinds of engines4 ,if none of the connecting-rods1 crank-pins or crank-pin bosses are injured1 it is not necessary to disconnect either side1 but if the injury is of such a nature that the coupling-rod must be taken down on one side1 the one on the other side must be taken down too4 ,if the main crank-pin and connecting-rod are not disabled1 both cylinders may be used even if one of the main wheels or tires is broken4 ,but even if one side of the engine must be entirely disconnected1 the engine may still be run with one cylinder and by driving one wheel4 ,if a main axle breaks the engine can usually be run1 but great caution must be exercised4 ,in such cases1 however1 if assistance or a telegraph office is near where the accident occurs1 it is usually best to send for assistance at once1 rather than take the risks which attend the attempt to run an engine so seriously injured4 ,,question #ebd4 ,what must be done when a trailing or leading driving-wheel1 tire or axle breaks8 ,answer4 ,very much the same course must be pursued as was described in the previous answer1 although it is generally less difficult to run with a trailing or leading axle broken than it is when the main axle has met with such an accident4 ,,question #ebe4 ,what must be done if an engine-truck wheel or axle breaks8 ,answer4 ,it is usually best to chain up the end of the truck-frame over the broken axle or wheel to the engine frame and place a cross-tie across the other end of the truck-frame1 between it and the engine frame1 so that the weight of the engine may rest on the cross-tie4 ,if a part of the flange or a piece of the wheel is broken out1 the wheels should be turned around so that the unbroken part will rest on the rail1 and they should then be chained or otherwise fastened so that they cannot revolve1 and thus be made to slide on the rails and carry the weight of the engine in that way4 ,the same plan is employed if a tender wheel breaks1 but one end of a tender-truck frame must be chained up4 ,it is usually necessary to place a cross-tie across the top of the tender1 and fasten the chains to it4 ,,question #ebf4 ,what must be done in case a driving-spring1 spring-hanger or equalizing-lever breaks8 ,answer4 ,as the breaking of a spring or spring-hanger may cause a more serious accident1 the engine and train should be stopped as soon as possible after it occurs4 ,if the hanger is broken and there is a duplicate on hand1 it should be substituted in place of the broken one4 ,if there is no duplicate1 then the spring should be taken down1 and a wooden block be placed between the top of the driving-box and the frame to support the weight which before rested on the spring4 ,in order to insert this block1 if it is a front spring which is broken1 it is usually best to raise the engine with jack-screws or run the back wheels on inclined blocks of wood placed under each of the back wheels4 ,this raises the weight off from the front-wheels1 and the block can then be inserted between the box and frame4 ,if it is one of the springs over the back wheels which is broken1 the front wheels should be run on the wooden wedges4 ,such wedges can soon be cut out of a cross-tie with an axe1 or by sawing a square stick of wood diagonally it will make two such wedges4 ,the end of the equalizing lever next to the broken spring must be supported by inserting a piece of wood under it4 ,this will usually be held securely by the weight which is suspended from the opposite end1 bearing the blocked end down on the block4 ,,question #ebg4 ,what should be done if an engine-truck or tender spring breaks8 ,answer4 ,very much the same course must be pursued that is employed when a driving-spring breaks1 excepting that usually the weight can be lifted off from a truck-box easier by placing a jack under the end of the truck-frame than by the method described4 ,usually1 too1 each of the truck-springs supports the weight on two of the wheels1 so that the two boxes must be blocked up4 ,,question #ebh4 ,what must be done in case the engine-frame is broken8 ,answer4 ,usually very little need be done excepting to exercise more than usual caution in running1 and to reduce the speed4 ,of course the breakage of a frame may disable the engine1 but ordinarily in such accidents that is not the case4 ,,question #ebi4 ,how can it be known if an eccentric has slipped on the axle8 ,answer4 ,it is indicated at once by the irregular sound of the exhaust1 or1 as locomotive runners say1 the engine will be 8lame40 ,,question #ecj4 ,when it is known that an eccentric has slipped1 how can it be learned which is the one that is misplaced8 ,answer4 ,this can usually be learned by examining the marks which should always be made on the eccentrics and on the axles4 ,if no such marks have been made by the builder of the engine1 the runner himself should make them1 after the valves have been set correctly4 ,the effect upon the valve when an eccentric slips is either to increase or diminish the lead4 ,therefore1 by running the engine slowly with the link first in full forward and then in full back gear1 and observing whether steam is admitted at each end of the cylinder just before the crank reaches the dead points1 it can be known which eccentric has moved4 ,if it has slipped in one direction the lead will be increased and steam will be admitted to the cylinder some time before the piston reaches the end of the stroke4 ,if it has moved the opposite way1 the lead will be diminished and steam will not be admitted until after the piston has reached the end of its stroke4 ,the admission of steam will be indicated by its escape from the cylinder cocks4 ,,question #eca4 ,if by any means the valve stem or either of the eccentric rods should be lengthened or shortened1 how can it be known8 ,answer4 ,the crank on one side should be placed at one of the dead points and the cylinder-cocks opened2 then admit a little steam to the cylinder1 by opening the throttle-valve slightly1 and throw the reverse lever from full gear forward to full gear backward1 and observe whether steam escapes all the time from the end of the cylinder at which the piston stands4 ,then repeat the operation with the crank at the other dead point4 ,if either of the eccentric rods or the valve stem have been lengthened or shortened1 it will cause the valve to cover the steam-port either at the front or back end of the cylinder1 so that no steam will escape from the cock at that end4 ,if the length of one of the eccentric rods has been changed1 then when the altered rod is in gear the valve will have too little or no lead at one end of the cylinder and too much at the other4 ,if1 therefore1 this occurs when the forward rod is in gear and not in back gear1 it indicates that the length of the forward rod has been altered4 ,if the reverse occurs it shows that it is the back-motion rod whose length has been changed4 ,it must be observed that if the length of an eccentric rod is altered the lead will be changed only at that part of the link which is operated by the altered rod4 ,that is1 if the forward eccentric rod is too long or too short1 the lead at the front and back ends of the cylinder in forward gear only will be affected4 ,if the back eccentric rod is changed the valve will be affected only in back gear4 ,if1 however1 the length of the valve stem is changed1 the lead will be changed in both forward and back gear4 ,the valves on each side of the engine can1 of course1 be tested in the same way4 ,,question #ecb4 ,when it is discovered which eccentric has slipped1 how should it be reset8 ,answer4 ,if it has been marked1 it is simply turned back so that the marks correspond with each other again4 ,this is done by first loosening the set-screws1 and1 after the eccentric is turned to the proper place1 tightening them up again4 ,when an eccentric slips it is often caused by the cutting of the eccentric-straps1 valve or other part of the valve-gear1 so that these should always be examined to see whether they are properly oiled4 ,if the eccentrics have not been marked1 the valve may be set by placing the crank at the forward dead-point1 and the reverse lever in the front notch of the sector and the full part of the forward-motion eccentric above the axle4 ,then admit a little steam into the steam-chest1 open the cylinder cocks1 and move the forward-motion eccentric slowly forward until steam escapes from the front cylinder cock1 which will show that the steam-port is opened and the valve has some lead4 ,to set the backward-motion eccentric the crank is placed in the same position1 but the reverse lever is thrown into the back notch and the full part of the eccentric is placed below the axle4 ,then move this eccentric forward until steam escapes from the front cylinder cock as before4 ,in order to verify the position of the eccentrics the crank may be placed at the back dead-point and the reverse lever moved backward and forward1 at the same time observing whether steam escapes from the back cylinder cock when the link is in back and forward gear4 ,,question #ecc4 ,what should be done in case an eccentric-strap or rod1 or rocker arm or shaft1 or the valve stem breaks8 ,answer4 ,if an eccentric-strap or rod breaks1 the broken rod and strap should be taken down1 and the valve-stem disconnected from the rocker and the valve fastened in the middle position of the valve face1 and the engine should be run with one cylinder only4 ,the same course must usually be pursued if a rocker breaks4 ,if the valve-stem breaks1 it is not necessary to disconnect the link and eccentric rods1 but simply to fasten the valve in the centre of the valve face4 ,,question #ecd4 ,if a link hanger or saddle1 or a lifting arm should break1 what may be done8 ,answer4 ,the valve-gear may be used on that side of the engine by putting a wooden block in the link slot above the link block1 so as to support the link near the position at which it works the valve full stroke forward4 ,of course the engine can then be run in only one direction1 and should therefore be run with the utmost caution4 ,if1 however1 it should be necessary to back the train on a side track1 it can be done by taking out the wooden block and substituting a longer one1 so that the link will be supported in a position near that at which it works the valve full stroke backward4 ,these blocks must be fastened in some way1 either with rope or twine1 so that they will be held in their position when the engine is at work4 ,,question #ece4 ,if the lifting shaft itself or its vertical arm1 the reverse lever or rod1 should break1 what can be done8 ,answer4 ,if it is impossible to devise any temporary substitute or method of mending them1 both links can be blocked up as described above4 ,,question #ecf4 ,in case the throttle-valve should fail1 what should be done8 ,answer4 ,if such an accident occurs1 especially if it happens about a station1 it is attended with great danger4 ,if it is found that steam can not be shut off from the cylinders with the throttle-valve1 then the reverse lever should be placed in the middle of the sector4 ,if this does not prevent the engine from moving1 the reverse lever should be alternately thrown into forward and then into back gear1 and at the same time every aperture1 such as the safety-valve and heater cocks1 should be opened1 and every means be taken to cool the boiler as quickly as possible4 ,the fireman should open the furnace door1 close the ash-pan dampers1 and start the blower so as to draw a strong current of cold air into the furnace and through the tubes4 ,at the same time the injector should be started and the fire drawn as quickly as possible4 ,after the boiler is cooled1 the cover of the steam-dome may be removed and the valve examined if the defect can not be discovered in any other way4 ,of course if the accident occurs on the open road1 the train must be at once protected by sending out signals in each direction4 ,,question #ecg4 ,what must be done in case a coupling breaks8 ,answer4 ,when a coupling between the cars or tender breaks1 if the front end of the train is immediately stopped1 there will be danger that the back end of it1 which is broken loose1 will run into the front end1 and thus do great damage4 ,as it always occurs1 when a coupling of a passenger train breaks1 that the signal bell in the cab is rung1 the first impulse of a runner under such circumstances is to stop the engine4 ,he should1 however1 be careful not to do so if on shutting off steam he finds that the train has broken in two1 but should at once open the throttle in order to get the front end of the train out of the way of the rear end4 ,the ease with which the speed of a train is arrested with continuous brakes has increased the danger of accident from this cause4 ,usually a runner learns by the sudden start of the engine that the train has separated1 and when that occurs he should never apply the brakes4 ,,question #ech4 ,if from any cause the supply of water in the tender becomes exhausted1 what must be done8 ,answer4 ,it is best1 if it can be done without risk of injury to the engine1 to run the train on a side track and then draw the fire4 ,if no water can be obtained near enough to supply the tender with buckets1 help must be sent for2 but if there is a well1 stream or pond of water near1 the tender can be partly filled by carrying water4 ,,question #eci4 ,in case an engine becomes blockaded in a snow storm with plenty of fuel1 but runs out of water1 what can be done8 ,answer4 ,snow should be shoveled into the tender and steam admitted through the heater cocks so as to melt the snow4 ,,question #edj4 ,if a locomotive without an injector should be obstructed in a snow storm or in any other way so that it could not move1 and therefore could not work the pumps1 what should be done in case the water in the boiler should get low8 ,answer4 ,the weight of the engine should be lifted off from the main driving-wheels and the coupling rods disconnected from the main crank-pin1 so that the main wheels can turn without moving the engine4 ,these can then be run and the pumps thus be worked4 ,the weight can usually be most conveniently taken off from the main wheels by running the trailing wheels on wooden blocks1 and thus raising up the back end of the engine4 ,,question #eda4 ,if it is impossible1 in a snow storm or in very cold weather1 to keep steam in the boiler without danger1 what should be done8 ,answer4 ,draw the fire1 blow all the water out of the boiler1 empty the tanks1 disconnect the hose and slacken up the joints in the pumps and injector so that all the water in them can escape1 and thus prevent them from freezing up4 ,,part ,,xxix4 ,,accidents ,,and ,,injuries ,,to ,,persons4 ,,question #edb4 ,in case an accident occurs and one or more persons are seriously injured1 what can be done by those present8 ,answer4 ,in such cases it very often happens that with knowledge and sufficient coolness to apply that knowledge1 one or more non-medical persons who are present when an accident occurs can do as much or more toward saving life and allaying pain1 before a doctor comes1 than he can afterwards4 ,the following cases cited by ,dr4 ,howe in his book on 8,emergencies0 will illustrate this3 8,case #a4--;,a machinist was admitted to a ,new ,york hospital suffering from wounds of the wrist and palm of the hand4 ,on arriving at the hospital the entire clothing on one side of his body was saturated with blood1 from the loss of which he was partly insensible4 ,on making an examination1 it was found by the surgeon that a folded handkerchief was bandaged over the centre of the wrist1 and that the wound in the palm of the hand was untouched4 ,the pad was placed on the wrist1 as if the greatest care had been exercised to avoid pressing on either of the two arteries4 ,the bleeding in this case could easily have been controlled if the bandage and pad had been properly applied4 ,the patient1 however1 developed erysipelas1 and1 not having sufficient vitality to carry him through1 died the fifth day40 8,case #b4--;,a laborer fell from the front platform of a car at ,harlem1 and had his right foot crushed by one of the wheels4 ,an ordinary bandage was placed on the limb without any compress over the vessels4 ,in bringing the man to the hospital1 the rough jolting of the carriage set the wound bleeding1 and by the time he reached his destination he was apparently lifeless4 ,the vessels were tied and stimulants administered1 but he never rallied4 ,death occurred six hours after his admission4 ,his injuries1 independent of the bleeding1 might indeed have terminated his life2 still the chances would have been in his favor if a compress had been applied to the limb to prevent bleeding4 ,the fact that such a thing was not done shows either culpable negligence or deplorable ignorance40 ,many similar cases constantly occur where a little intelligent timely action of those present would save the life of an injured person1 who without such help must die before professional surgical aid can be obtained4 ,,question #edc4 ,when it is found that one or more persons are seriously injured1 what is the first thing to be done8 ,answer4 ,the first thing to do is to extricate the person or persons from the danger1 and at the same time send a messenger for a doctor4 ,if it is doubtful if one can be obtained by sending in one direction1 send two or more messengers in different directions4 ,,question #edd4 ,to what kind of injuries are locomotive runners and other persons employed or traveling on railroads exposed8 ,answer4 ,they are liable to be bruised or crushed in case of collision or running off the track1 or of injury from falling off the train1 or of being run over by a moving train4 ,brakemen and others whose duty it is to couple cars are liable to have their hands1 arms or bodies crushed between the cars1 and locomotive runners are sometimes burned or scalded if an accident happens to their engines4 ,train-men are also frequently exposed to very great cold in winter and heat in summer1 and are thus liable to be frost-bitten or sun-struck4 ,passengers are seldom injured excepting through their own carelessness1 unless in cases of collision or running off the track and the destruction of the cars4 ,strangers and even railroad employes are frequently run over by trains while walking on the track1 and frequent accidents occur to deaf people in this way1 and it is not very unusual to hear of train-men who sit on the main track at night while their trains are waiting on the side-track for another train to pass1 go to sleep while in that position1 and then are run over by the passing train4 ,,question #ede4 ,when persons are crushed or dangerously wounded1 what are the chief immediate sources of danger and death when their wounds are not necessarily fatal8 ,answer4 ,first1 excessive bleeding in case an artery is ruptured2 second1 the shock to the whole system1 from which the sufferer may not have the strength to recover4 ,,question #edf4 ,when does bleeding from a wound become dangerous8 ,answer4 ,profuse bleeding is always dangerous1 but it should be remembered that bleeding occurs from two sources3 first from the arteries1 which are the vessels which convey the blood from the heart1 and second from the veins1 through which the blood flows back to the heart4 ,the first is called arterial bleeding and the second venous bleeding4 ,now it must be remembered that the heart is the great force-pump of the body1 and that it supplies all parts of the body with blood1 somewhat as the feed-pump of a locomotive supplies the boiler with water4 ,the arteries referred to fulfill the same purpose that the feed-pipe does to a locomotive pump--they convey the fluid from the pump to the place where it is needed4 ,now the blood is forced into these arteries with a certain amount of pressure1 so that if any of them are cut or injured the blood will flow out in a jet or spurt just as the water will escape from a feed-pipe if that is ruptured4 ,the blood which flows through the veins back to the heart may1 on the other hand1 be compared to the water in the supply pipes of a locomotive pump1 that is1 there is very little pressure on it1 and therefore if they are injured the flow of blood from them is less rapid than from the arteries4 ,it will therefore be seen that arterial bleeding is much more dangerous1 because the blood flows from them under a pressure4 ,,question #edg4 ,how can arterial bleeding be distinguished from venous bleeding8 ,answer4 ,the blood is of a bright scarlet color1 and is forced out in successive jets2 each jet corresponds with the movements of the heart4 ,this characteristic spurting is caused by the intermittent force-pump action of the heart1 driving out the blood4 ,venous bleeding is distinguished from arterial by the dark-blue color of the blood when flowing from the wound4 ,it never flows in repeated jets1 but oozes slowly from the wounded surfaces4 ,venous blood is traveling toward the heart1 and there is consequently little force behind to cause a more rapid flow4 ,this form of bleeding is comparatively harmless1 unless occurring from very large veins4#aah #aah 8,emergencies and ,how to ,treat ,them10 by ,joseph ,w4 ,howe1 ,m4 ,d4 ,,question #edh4 ,how can the bleeding be stopped in case an artery is cut or ruptured8 ,answer4 ,the most efficient and available method is the application of ,,pressure on the artery ,,between ,,the ,,wound ,,and ,,the ,,heart4 ,under ordinary circumstances this can be most effectively done with what is called a field tourniquet1 which is simply a handkerchief passed around the limb above the wound1 the ends of which are then tied together4 ,a pad is then made1 either of cloth rolled up1 a piece of wood1 or a round stone about the size of a hen's egg well wrapped1 or any substance from which a firm pad can be quickly made1 which is placed over the artery4 ,the handkerchief is then placed over the pad and a short stick put through it on the opposite side of the limb and twisted around until the pad compresses the artery firmly4 ,while the tourniquet is being prepared1 some one should compress the artery with his fingers or thumb1 so as to prevent as much loss of blood as possible4 ,,question #edi4 ,what is the position of the arteries in the body and how can their location be known8 ,illustration3 ,fig4 #bcj4 ,answer4 ,the position of the principal arteries is shown in fig4 #bcj4 ,they proceed from the heart h with branches1 a1 a1 and b1 b1 which extend along each limb4 ,these branches subdivide again below the knees and elbows1 and again in the hands and feet4 ,the position of the arteries can be felt by their pulsation at almost any part of them1 but when they are buried below the muscles it is more difficult than when they are near the surface4 ,,question #eej4 ,in case of a wound and rupture of the arteries in the arm1 what should be done8 ,answer4 ,the artery at a should be firmly compressed with the thumb until a bandage and pad from which a tourniquet can be made are prepared4 ,the pad should then be applied over the artery and compressed as explained in answer to ,question #edh4 ,the bleeding can also be stopped by placing a round piece of wood or other form of pad between the arm at a and the body and then tying the arm tightly against the body1 so that the pad will be pressed against the arm4 ,,question #eea4 ,in case of rupture to an artery below the knee1 where should the pressure be applied8 ,answer4 ,the artery approaches near the surface at c1 c1 immediately back of the knee1 where it is represented in dotted lines in fig4 #bcj4 ,pressure should therefore be applied at that point first with the thumb until a tourniquet can be applied4 ,the bleeding can also be stopped by elevating the leg and allowing it to rest on the back of a chair or other similar support4 ,the weight of the leg will then bring sufficient pressure on the artery to stop the bleeding4 ,a towel or other soft material should be placed over the back of the chair1 so that the pressure will not be too painful to the sufferer4 ,,question #eeb4 ,if an artery is ruptured in the leg above the knee1 where should the pressure be applied8 ,answer4 ,in the thigh at b1 where the beating or pulsations in the artery can be distinctly felt4 ,the reader should familiarize himself with the position of the arteries by feeling their location in his own body4 ,by doing so he may be able to save the life of a companion or other person in case of accident1 whereas without such knowledge the injured person would die4 ,,question #eec4 ,after the arterial bleeding has been stopped1 if blood should continue to ooze out of the wound1 what should be done8 ,answer4 ,the wound should be filled with lint or cotton waste2 and the limb then be bandaged by beginning at its extremity and wrapping the bandage closely and evenly around it so as to bring1 as nearly as possible1 an equal pressure on the whole of it4 ,bandaging the limb in this way up to the point where the pressure is applied to the artery1 will prevent swelling1 and the veins will be compressed so that the blood will not flow from their torn extremities4 ,,question #eed4 ,when the bleeding has been stopped1 what should be done8 ,answer4 ,the injured person should be laid in as comfortable a place as can be procured for him1 and should be given a moderate drink of water4 ,if much exhausted1 two or three tablespoonsful of brandy or whisky1 mixed with an equal quantity of water1 should be given first1 and smaller quantities1 of not ,,more ,,than ,a ,,tablespoonful at a time1 should then be given every half hour4 ,usually wounded persons are given too much stimulant1 so that frequently they are injured more than they are benefited thereby4 ,after a person has lost much blood1 he feels an intolerable thirst1 but if too much water is given him1 he is apt to become sick and vomit1 which weakens him still more4 ,it is therefore best to give him very little water1 say a teaspoonful at a time1 after the first drink1 or if ice can be obtained1 give the sufferer pieces of ice frequently1 which can be allowed to melt slowly in his mouth4 ,,question #eee4 ,when a person is insensible1 what should be done for him8 ,answer4 ,lay him down in as comfortable a place as the circumstances will permit1 and protect him from cold1 rain or hot sun1 as may be needed4 ,a common error is to place injured and insensible persons in an erect position or in a chair4 ,if he is insensible he should always be laid down with his head slightly lower than his body4 ,then water should be dashed two or three times on his face1 and warm bricks1 stones or pieces of iron1 such as coupling links or pins1 applied to his feet and in the arm-pits and between the thighs1 being careful that the warm objects applied are not hot enough to burn4 ,then cover the person with blankets1 heavy coats or anything else which will keep him warm4 ,wounded persons soon become cold and chilled1 the effects of which are very injurious1 and therefore especial pains should be taken to keep them warm4 ,in very cold weather there is great danger that injured persons will be frost-bitten1 which must be carefully guarded against4 ,in case of shock1 when the injured person lies pale1 faint1 cold and sometimes insensible1 with feeble pulse and labored breathing1 anything like excitement must be avoided1 as it tends to exhaust the patient4 ,all assistance and attention should be given to a wounded person with the least noise and excitement1 and all crowds and idle spectators should be driven away and every effort made to keep the sufferer comfortable and quiet4 ,if food is given it should be in the form of beef tea or broth1 and in small quantities at a time4 ,,question #eef4 ,in case any bones are broken1 what should be done8 ,answer4 ,the limb should be supported as comfortably as possible until a doctor's services can be obtained4 ,there is danger with a broken limb that the bones will protrude through the flesh and skin1 to avoid which the limb should be placed in a natural position and laid on a pillow1 car cushion or other soft object4 ,this should then be wrapped around the limb and tied in this position1 so as to prevent any movement of the broken bones4 ,,question #eeg4 ,if a person is crushed or severely burned1 what should be done8 ,answer4 ,the immediate danger from such injuries arises from the 8shock0 to the system4 ,it is usually best to bandage the part which is crushed until surgical aid can be obtained1 and the sufferer treated as explained in answer to ,question #edh4 ,,question #eeh4 ,what should be done for a person who has been burned or scalded8 ,answer4 ,lint or cotton waste saturated with molasses and water should be applied to the wound1 or the latter should be dusted with wheat flour1 and then dressed with lint or cotton waste1 and loosely bandaged4 ,if the injury should be severe1 a shivering followed by depression is very likely to come on4 ,to check this1 warmth in the form of hot applications and stimulants should be used1 as already explained4 ,,question #eei4 ,what should be done for a frost-bite8 ,answer4 ,warmth should be applied to the frozen part very gradually by rubbing with snow or pouring cold water on it4 ,the occurrence of stinging pain1 with a change in color1 is a signal to stop all rubbing or other measure which might excite inflammation4 ,if the frozen part turns black the next day1 a poultice should be applied4 ,if persons exposed to the cold become very much exhausted or sleepy1 stimulants should be given1 as explained in answer to ,question #eed1 and the body briskly rubbed with the hands and warm flannel or other woolen material4 ,,question #efj4 ,how should a person be treated who has been sun-struck8 ,answer4 ,apply cold water or ice to the head1 place the sufferer in a cool place1 and make him comfortable4 ,after being sun-struck the person should not work for some days or weeks thereafter1 until his health and strength are fully recovered4 ,,part ,,xl4 ,,responsibility ,,and ,,qualifications ,,of ,,locomotive ,,runners4#aai #aai ,,note4--,the greater part of this chapter is a translation from ,prof4 ,george ,kosak's 8,katechismus der ,einrichtung und des ,betriebes der ,locomotive40 ,,question #efa4 ,what are the dangers to which the runner and the fireman are exposed by their work on the engine8 ,answer4 ,runners and firemen are not only exposed to great bodily injury or even death by every accident which may happen to their engine1 but unless they are very careful to preserve their health it is quickly destroyed by the constant changes of the weather to which their position exposes them1 and also by the effect of the heat of the fire and by the smoke by which they are often surrounded4 ,in order to protect themselves in a measure from the injurious effects of change of weather1 smoke1 cold1 etc41 frequent bathing and cleansing of the skin are absolutely necessary1 and also the wearing of a woolen undershirt next the skin at all seasons4 ,the gases of coal which pour out of the furnace-door1 if it is opened when the throttle is closed1 have an especially injurious effect on the throat1 lungs1 etc4 ,they should always see to it1 therefore1 that the blower is always started before the fire-door is opened1 in order that these injurious gases1 which have collected during a halt1 may be drawn forward and up the smoke-stack by the draft4 ,the steady1 loud clatter which the engine makes while running has an injurious influence on the nervous system4 ,the runner should therefore endeavor to lessen these shocks of the engine as far as possible by keeping watch over it and keeping its parts accurately adjusted4 ,in order to keep himself fresh and strong in his service1 which is extremely exhaustive to body and mind1 the runner must try to strengthen himself by regular1 temperate living1 and eating abundant nourishing food4 ,the common use of strong drinks1 which undermines the mental and physical strength of men1 should be avoided by a person occupying the exhaustive and responsible position of a locomotive runner4 ,if in ordinary life a drunken man is unfit for any simple work1 how shall a drunken runner or fireman undertake the difficult management of so great1 so delicate and so costly a machine as a locomotive8 ,how can hundreds of men quietly trust their lives and limbs to such a man1 whom no one can help despising8 ,rightfully1 therefore1 conscientious railroad managers place the greatest stress on the sobriety of the runners and firemen1 and instantly discharge from their service those who give themselves up to a passion for drink4 ,owing to the demands which their daily labor makes upon their strength and endurance1 locomotive runners should be careful not to increase the drain by dissipation1 irregular hours or overwork4 ,there seems to be something about the power of endurance of the human frame analogous to the capacity of a bar of iron or steel to resist strains4 ,so long as the strains do not exceed the elastic limit1 that is if the bar recovers its original length when the strain is removed1 it will bear millions of such strains without becoming weaker2 but if it is strained so hard that it is permanently stretched1 then comparatively few applications of the force will rupture the bar4 ,in a similar way1 if the strain or fatigue which a man endures is no more than he will recover from after the ordinary rest1 he can endure an almost unlimited number of such strains1 but if the fatigue exceeds his 8elastic limit10 then he soon becomes permanently injured thereby4 ,it often happens that an excessive amount of work is unavoidable1 but when it can be avoided it should be by those who wish to preserve their health and strength4 ,in order to save themselves from great injuries1 runners and firemen should always act with the greatest caution1 and never rush carelessly into danger4 ,they should never adopt the principle of foolhardy and thoughtless people1 who by the consciousness of continual danger fall into the habit of carelessly 8trusting to their luck10 etc4 ,on the contrary1 they should always face the danger with their eyes open and with the greatest conscientiousness4 ,many try to show great courage by scorning the danger1 and some such even wish to meet a little in order to be able to show their pluck4 ,these should bear in mind that they have a great responsibility laid upon them1 and that it is not alone their own well-being or life which is at stake in case of any mishap1 but that by their careless behavior they may wound or kill the helpless people who are committed to their care1 cause incalculable misery by robbing families of their sole support and of their children2 and bring great sorrow and mourning to their fellow-men4 ,the thought of the curse and the despair of the survivors may give sleepless hours even to a locomotive runner who knows himself to have been without any fault regarding an accident2 how much more must it be with him who cannot give himself this assurance8 ,there are not wanting instances in which the runner who caused such an accident by his thoughtlessness1 driven to despair by his own heavily-burdened conscience1 went miserably to ruin4 ,,question #efb4 ,what requirements and duties should every locomotive runner fulfill8 ,answer4 ,every locomotive runner should fulfill the following requirements and duties3 #a4 ,he should have an exact knowledge of the engine intrusted to him1 and a general knowledge of the nature and construction of steam engines generally4 ,likewise1 he should be perfectly familiar with the management of the boiler1 the running of the engine1 and the way of keeping the working parts in good condition2 also1 with the forms and peculiarities of the line of road on which he runs1 the rules which govern the running of trains and with the signal system adopted4 #b4 ,health and bodily strength he must have in abundant measure in his position1 which is exhausting and in which he is exposed to all sorts of weather4 #c4 ,he should have a good1 plain common-school education1 and be ready at reading1 writing and arithmetic4 #d4 ,he should always carry out exactly and cheerfully the regulations of the service1 or the instructions given him by special orders from the officers over him4 #e4 ,faithfulness1 frankness and honesty1 which characterize an upright man in ordinary life1 and also the strictest temperance in the use of strong drink1 he should possess in a high degree in his very responsible position4 #f4 ,he should have acquired a certain degree of skill in putting together and taking apart locomotives1 and also in repairing separate parts of them4 ,it is desirable that he should always be present when his own engine is taken apart1 put together or repaired1 in order that he may acquire a thorough knowledge of its condition and learn to understand properly the importance of its various parts4 #g4 ,in caring for his engine he must preserve perfect cleanliness and order1 and in using fuel he must manifest the greatest care and rigid economy4 #h4 ,whenever there is danger1 coolness and self-possession are indispensably necessary1 and any thoughtlessness or recklessness is to be strictly avoided4 #i4 ,towards his superior officers his behavior should be respectful and obliging2 towards those under him1 patient and kindly1 and at all times he should avoid profanity and all intemperate language4 ,he should endeavor1 as far as possible1 to instruct the fireman who accompanies him and make him familiar with the construction and management of the engine1 and should see that he does his work strictly in accordance with his instructions4 ,it is the fireman's duty to follow the runner's instructions strictly1 and in case of any sudden disability of the runner he must stop the engine in accordance with the instructions given him1 and then give the proper signals for help1 until another runner arrives4 ,in the meanwhile the engine is to be kept at a halt with all the usual precautions4 #aj4 ,the runner should try to keep himself informed of the progress and improvement of locomotives by reading suitable hooks and technical periodicals1 and when possible acquire some skill in geometrical and mechanical drawing1 in order to accustom himself to accurate work and sound and systematic thinking4 ,,question #efc4 ,what studies should mechanics1 locomotive runners and firemen take up1 and what technical books should they read8 ,answer4 ,as already stated1 they should know how to read and write their own language1 and understand arithmetic and have some knowledge of geography4 ,every locomotive runner and fireman has a good deal of spare time1 a part of which he can devote to study1 and all of them1 even if they have not had the advantage of early education1 could by industry and perseverance acquire a knowledge of 8reading1 writing and ciphering40 ,the assistance of a good teacher should always be procured1 if possible4 ,with so much knowledge1 some book on natural philosophy can be read to advantage1 and then some book on mechanics4 ,the following list of books is given1 which the student will do well to read in the order in which they are named4 ,it should always be remembered1 however1 that the mere buying of books contributes very little knowledge to the owner4 ,it is the reading and understanding them which 8increases knowledge40 ,,list ,,of ,,books ,,for ,,mechanics1 ,,locomotive ,,runners1 ,,firemen1 ,,etc4 ,a ,hand ,book of the ,steam ,engine1 by ,john ,bourne2 published by ,longmans1 ,london2 #b4jj4 ,a ,catechism of the ,steam ,engine1 by ,john ,bourne2 published by ,longmans1 ,london2 #b4jj4 ,lessons in ,elementary ,physics1 by ,balfour ,stewart2 published by ,macmillan ,co41 ,new ,york2 #a4ej4 ,experimental ,mechanics1 by ,prof4 ,ball2 published by ,macmillan ,co41 ,new ,york2 #f4jj4 ,the ,new ,chemistry1 by ,prof4 ,j4 ,p4 ,cooke2 published by ,appleton ,co41 ,new ,york2 #b4jj4 ,elementary ,treatise on ,heat1 by ,balfour ,stewart2 published by ,macmillan ,co41 ,new ,york2 #c4jj4 ,combustion of ,coal1 by ,c4 ,wye ,williams2 published by ,lockwood ,co41 ,london2 #a4bj4 ,a ,treatise on ,steam ,boilers1 by ,robert ,wilson2 published by ,lockwood ,co41 ,london2 #c4jj4 ,link-,valve ,motion1 by ,wm4 ,s4 ,auchincloss2 published by ,d4 ,van ,nostrand1 ,new ,york2 #c4jj4 ,the ,conservation of ,energy1 by ,balfour ,stewart2 published by ,appleton ,co41 ,new ,york2 #a4ej4 ,richards' ,steam ,engine ,indicator1 by ,charles ,t4 ,porter2 published by ,longmans1 ,london2 #b4ej4 ,,plates ,,plate ,,iv4 ,,dimensions1 ,,weight1 ,,etc41 ,,of ,,four-,,wheeled ,,switching ,,locomotive1 ,,by ,,the ,,hinkley ,,locomotive ,,works1 ,,boston1 ,,mass4 ,gauge of ,road #d ft4 #h in4 ,number of ,driving-,wheels #d ,number of ,front ,truck-,wheels ,none4 ,number of ,back ,truck-,wheels ,none4 ,total ,wheel ,base #f ft4 #i in4 ,distance between ,front and ,back ,driving-,wheels #f ft4 #i in4 ,total ,weight of ,locomotive in working order #dh1jjj lbs4 ,total ,weight on ,driving-,wheels #dh1jjj lbs4 ,diameter of ,driving-,wheels #ej in4 ,diameter of ,truck-,wheels ,none4 ,diameter of ,cylinders #ae in4 ,stroke of ,cylinders #bb ,outside ,diameter of smallest ,boiler ring #dd in4 ,size of ,grate #c #c ft4 ,number of ,tubes #aba ,diameter of ,tubes #b in4 ,length of ,tubes #aj ft4 ,square ,feet of ,grate surface #aa ,square ,feet of ,heating surface in ,fire-,box #ga ,square ,feet of ,heating surface in ,tubes #ehj ,total ,feet of ,heating surface #fea ,exhaust ,nozzles--single or double ,double4 ,diameter of ,nozzle #b in4 ,size of ,steam ,ports #aj #a in4 ,size of ,exhaust ,ports #b in4 ,throw of ,eccentrics #d in4 ,outside ,lap of ,valve in4 ,inside ,lap of ,valve ,none4 ,size of ,main ,driving-axle ,journal #f #g in4 ,size of other ,driving-axle ,journal #f #g in4 ,size of ,truck-axle ,journal ,none4 ,diameter of ,pump ,plunger #a in4 ,stroke of ,pump ,plunger #bb in4 ,capacity of ,tank #a1bjj gallons4 ,illustration3 ,plate ,,iv4 ,,four-,,wheeled ,,switching ,,locomotive1 ,,by ,,the ,,hinkley ,,locomotive ,,works1 ,,boston1 ,,mass4 ,scale1 in4 #a ft4 ,,plate ,v4 ,,dimensions1 ,,weight1 ,,etc41 ,,of ,,eight-,,wheeled 8,,american0 ,,locomotive ,,by ,,the ,,baldwin ,,locomotive ,,works1 ,,philadelphia4 ,gauge of ,road #d ft4 #h in4 ,number of ,driving-,wheels #d ,number of ,front ,truck-,wheels #d ,number of ,back ,truck-,wheels ,none4 ,total ,wheel ,base #ba ft4 #i in4 ,distance between centres of ,front and ,back ,driving-,wheels #if in4 ,total ,weight of ,locomotive in working order #fe1jjj lbs4 ,total ,weight on ,driving-,wheels #db1jjj lbs4 ,diameter of ,driving-,wheels #fj in4 ,diameter of ,truck ,wheels #bh in4 ,diameter of ,cylinders #af in4 ,stroke of ,cylinders #bd in4 ,outside ,diameter of smallest ,boiler ,ring #dh in4 ,size of ,grate #fe #cd in4 ,number of ,tubes #add ,diameter of ,tubes #b in4 ,length of ,tubes #aj ft4 #aa in4 ,square ,feet of ,grate surface #ae4e ,square ,feet of ,heating surface in ,fire-,box #ajj4f ,square ,feet of ,heating surface in ,tubes #hbe4d ,total ,feet of ,heating surface #ibf ,exhaust ,nozzles--single or double ,double4 ,diameter of ,nozzle #b to #c in4 ,size of ,steam ,ports #a #ae in4 ,size of ,exhaust ,ports #b #ae in4 ,throw of ,eccentrics #e in4 ,outside ,lap of ,valve in4 ,inside ,lap of ,valve in4 ,size of ,main ,driving-axle ,journal #g in4 dia4 #h in4 ,size of other ,driving-axle ,journal #g in4 dia4 #h in4 ,size of ,truck-axle ,journal #d #g in4 ,diameter of ,pump ,plunger #b in4 ,stroke of ,pump ,plunger #bd in4 ,capacity of ,tank #b1jjj gallons4 ,illustration3 ,plate ,v4 ,,eight-,,wheeled 8,,american0 ,,locomotive1 ,,by ,,the ,,baldwin ,,locomotive ,,works1 ,,philadelphia4 ,scale1 in4 #a foot4 ,,plate ,,vi4 ,,dimensions1 ,,weight1 ,,etc41 ,,of ,,eight-,,wheeled 8,,american0 ,,locomotive ,,by ,,the ,,grant ,,locomotive ,,works1 ,,paterson1 ,n4 ,j4 ,gauge of ,road #d ft4 #h in4 ,number of ,driving-,wheels #d ,number of ,front ,truck-,wheels #d ,number of ,back ,truck-,wheels ,none4 ,total ,wheel ,base #ba ft4 #i in4 ,distance between centres of ,front and ,back ,driving-,wheels #h ft4 ,total ,weight of ,locomotive in working order #fb1jjj lbs4 ,total ,weight on ,driving-,wheels #db1jjj lbs4 ,diameter of ,driving-,wheels #fa in4 ,diameter of ,truck-,wheels #bh in4 ,diameter of ,cylinders #af in4 ,stroke of ,cylinders #bd in4 ,outside ,diameter of smallest ,boiler ,ring #dh in4 ,size of ,grate #fj #cd in4 ,number of ,tubes #adj ,diameter of ,tubes #b in4 ,length of ,tubes #aa ft4 ,square ,feet of ,grate surface #ad ,square ,feet of ,heating surface in ,fire-,box #ih ,square ,feet of ,heating surface in ,tubes #hje ,total ,feet of ,heating surface #ijc ,exhaust ,nozzles--single or double ,double4 ,diameter of ,nozzle #c to #c in4 ,size of ,steam ,ports #a #ad in4 ,size of ,exhaust ,ports #b #ad in4 ,throw of ,eccentrics #e in4 ,outside ,lap of ,valve in4 ,inside ,lap of ,valve ,none4 ,size of ,main ,driving-axle ,journal #f dia4 #g in4 ,size of other ,driving-axle ,journal #f dia4 #g in4 ,size of ,truck-axle ,journal #d dia4 #h in4 ,diameter of ,pump ,plunger #b in4 ,stroke of ,pump ,plunger #bd in4 ,capacity of ,tank #b1jjj gallons4 ,illustration3 ,plate ,,vi4 ,,eight-,,wheeled 8,,american0 ,,locomotive1 ,,by ,,the ,,grant ,,locomotive ,,works1 ,,paterson1 ,n4 ,j4 ,scale1 in4 #a ft4 ,,plate ,,vii4 ,,dimensions1 ,,weight1 ,,etc41 ,,of ,,eight-,,wheeled 8,,american0 ,,locomotive ,,by ,,the ,,danforth ,,locomotive ,,and ,,machine ,,co41 ,,paterson1 ,n4 ,j4 ,gauge of ,road #d ft4 #h in4 ,number of ,driving-,wheels #d ,number of ,front ,truck-,wheels #d ,number of ,back ,truck-,wheels ,none4 ,total ,wheel ,base #ba ft #b in4 ,distance between centres of ,front and ,back ,driving- ,wheels1 #g ft4 #i in4 ,total ,weight of ,locomotive in working order #fj1bjj lbs4 ,total ,weight on ,driving-,wheels #ch1cej lbs4 ,diameter of ,driving-,wheels #e ft4 #g in4 ,diameter of ,truck-,wheels #b ft4 #f in4 ,diameter of ,cylinders #ae in4 ,stroke of ,cylinders #bd in4 ,outside ,diameter of smallest ,boiler ,ring #c ft4 #aj in4 ,size of ,grate #ef #cd in4 ,number of ,tubes #acf ,diameter of ,tubes #b in4 ,length of ,tubes #aa ft4 ,square ,feet of ,grate surface #ac4e ,square ,feet of ,heating surface in ,fire-,box #hf ,square ,feet of ,heating surface in ,tubes #gge ,total ,feet of ,heating surface #hfa ,exhaust ,nozzles--single or double ,double4 ,diameter of ,nozzle #b in4 ,size of ,steam ,ports #a #ac in4 ,size of ,exhaust ,ports #b #ac in4 ,throw of ,eccentrics #e in4 ,outside ,lap of ,valve in4 ,inside ,lap of ,valve in4 ,size of ,main ,driving-axle ,journal #f in4 ,size of other ,driving-axle ,journal #f in4 ,size of ,truck-axle ,journal #d in4 ,diameter of ,pump ,plunger #b in4 ,stroke of ,pump ,plunger #bd in4 ,capacity of ,tank #a1hjj gallons4 ,illustration3 ,plate ,,vii4 ,,eight-,,wheeled 8,,american0 ,,locomotive1 ,,by ,,the ,,danforth ,,locomotive ,,and ,,machine ,,co41 ,,paterson1 ,n4 ,j4 ,scale1 in4 #a ft4 ,,plate ,,viii4 ,,dimensions1 ,,weight1 ,,etc41 ,,of ,,eight-,,wheeled 8,,american0 ,,locomotive ,,by ,,the ,,mason ,,machine ,,works1 ,,taunton1 ,,mass4 ,gauge of ,road #d ft4 #h ,in4 ,number of ,driving-,wheels #d ,number of ,front ,truck-,wheels #d ,number of ,back ,truck-,wheels ,none4 ,total ,wheel ,base #bb ft4 ,distance between centres of ,front and ,back ,driving-,wheels #h ft4 ,total ,weight of ,locomotive in working order #fb1jjj lbs4 ,total ,weight on ,driving-,wheels #dj1jjj lbs4 ,diameter of ,driving-,wheels #e ft4 #f in4 ,diameter of ,truck-,wheels #b ft4 #i in4 ,diameter of ,cylinders #a ft4 #e in4 ,stroke of ,cylinders #b ft4 ,outside ,diameter of smallest ,boiler ,ring #c ft4 #aj in4#abj ,size of ,grate #ff #ce in4 ,number of ,tubes #aee ,diameter of ,tubes #b in4 ,length of ,tubes #aa ft #b in4 ,square ,feet of ,grate surface #af4ch ,square ,feet of ,heating surface in ,fire-,box #aje ,square ,feet of ,heating surface in ,tubes #ijf ,total ,feet of ,heating surface #ajaa ,exhaust ,nozzles--single or double ,single4 ,diameter of ,nozzle #c in4 ,size of ,steam ,ports #ae #a in4 ,size of ,exhaust ,ports #ae #b in4 ,throw of ,eccentrics #d in4 ,outside ,lap of ,valve in4 ,inside ,lap of ,valve in4 ,size of ,main ,driving-axle ,journal #f #g in4 ,size of other ,driving-axle ,journal ,size of ,truck-axle ,journal #c #f in4 ,diameter of ,pump ,plunger #a in4 ,stroke of ,pump ,plunger #bd in4 ,capacity of ,tank #b1bej gallons4 #abj ,the ,boiler is made conical1 #df in4 diameter at the ,smoke-,box and #ej in4 at the ,fire-,box4 ,illustration3 ,plate ,,viii4 ,,eight-,,wheeled 8,,american0 ,,locomotive1 ,,by ,,the ,,mason ,,machine ,,works1 ,,taunton1 ,,massachusetts4 ,scale1 in4 #a ft4 ,,plate ,,ix4 ,,dimensions1 ,,weight1 ,,etc41 ,,of ,,eight-,,wheeled 8,,american0 ,,locomotive ,,by ,,the ,,hinkley ,,locomotive ,,works1 ,,boston1 ,,mass4 ,gauge of ,road #d ft4 #h in4 ,number of ,driving-,wheels #d ,number of ,front ,truck-,wheels #d ,number of ,back ,truck-,wheels ,none4 ,total ,wheel ,base #ba ft4 #d in4 ,distance between centres of ,front and ,back ,driving-,wheels #g ft4 #f in4 ,total ,weight of ,locomotive in working order #fc1jjj lbs4 ,total ,weight on ,driving-,wheels #da1jjj lbs4 ,diameter of ,driving-,wheels #fh in4 ,diameter of ,truck-,wheels #cj in4 ,diameter of ,cylinders #af in4 ,stroke of ,cylinders #bd in4 ,outside ,diameter of smallest ,boiler ,ring #df in4 ,size of ,grate #c ft4 #e ft4 ,number of ,tubes #aej ,diameter of ,tubes #b in4 ,length of ,tubes #aa ft4 ,square ,feet of ,grate surface #ae ,square ,feet of ,heating surface in ,fire-,box #ajj ,square ,feet of ,heating surface in ,tubes #gee ,total ,feet of ,heating surface #hee ,exhaust ,nozzles--single or double ,double4 ,diameter of ,nozzle #c in4 ,size of ,steam ,ports #ad #a in4 ,size of ,exhaust ,ports #b in4 ,throw of ,eccentrics #e in4 ,outside ,lap of ,valve in4 ,inside ,lap of ,valve ,none4 ,size of ,main ,driving-axle ,journal #g #g in4 ,size of other ,driving-axle ,journal #g #g in4 ,size of ,truck-axle ,journal #d #g in4 ,diameter of ,pump ,plunger #a in4 ,stroke of ,pump ,plunger #bd in4 ,capacity of ,tank #b1jjj gallons4 ,illustration3 ,plate ,,ix4 ,,eight-,,wheeled 8,,american0 ,,locomotive1 ,,by ,,the ,,hinkley ,,locomotive ,,works1 ,,boston1 ,,massachusetts4 ,scale1 in4 #a ft4 ,,plate ,x4 ,,dimensions1 ,,weight1 ,,etc41 ,,of ,,ten-,,wheeled ,,locomotive1 ,,by ,,the ,,baldwin ,,locomotive ,,works1 ,,philadelphia4 ,gauge of ,road #d ft #h in4 ,number of ,driving-,wheels #f ,number of ,front ,truck-,wheels #d ,number of ,back ,truck-,wheels ,none4 ,total ,wheel ,base #bc ft4 #f in4 ,distance between centres of ,front and ,back ,driving-,wheels #hh in4 ,total ,weight of ,locomotive in working order #gh1jjj lbs4 ,total ,weight on ,driving-,wheels #eh1jjj lbs4 ,diameter of ,driving-,wheels #ed in4 ,diameter of ,truck-,wheels #bf in4 ,diameter of ,cylinders #ah in4 ,stroke of ,cylinders #bd in4 ,outside ,diameter of smallest ,boiler ,ring #ej in4 ,size of ,grate #fj #cd in4 ,number of ,tubes #aeb ,diameter of ,tubes #b in4 ,length of ,tubes #ab ft4 #i in4 ,square ,feet of ,grate surface #ad4cg ,square ,feet of ,heating surface in ,fire-,box #id ,square ,feet of ,heating surface in ,tubes #ajad ,total ,feet of ,heating surface #aajh ,exhaust ,nozzles--single or double ,double4 ,diameter of ,nozzle #c to #c in4 ,size of ,steam ,ports #a #af in4 ,size of ,exhaust ,ports #b #af in4 ,throw of ,eccentrics #e in4 ,outside ,lap of ,valve in4 ,inside ,lap of ,valve in4 ,size of ,main ,driving-axle ,journal #g in4 dia4 #h in4 ,size of other ,driving-axle ,journal #g in4 dia4 #h in4 ,size of ,truck-axle ,journal #d #g in4 ,diameter of ,pump ,plunger #b in4 ,stroke of ,pump ,plunger #bd in4 ,capacity of ,tank #b1bjj gallons4 ,illustration3 ,plate ,x4 ,,ten-,,wheeled ,,locomotive1 ,,by ,,the ,,baldwin ,,locomotive ,,works1 ,,philadelphia4 ,scale1 in4 #a ft4 ,,plate ,,xi4 ,,dimensions1 ,,weight1 ,,etc41 ,,of 8,,mogul0 ,,locomotive1 ,,by ,,the ,,baldwin ,,locomotive ,,works1 ,,philadelphia4 ,gauge of ,road #d ft4 #h in4 ,number of ,driving-,wheels #f ,number of ,front ,truck-,wheels #b ,number of ,back ,truck-,wheels ,none4 ,total ,wheel ,base #bb ft4 #h in4 ,distance between centres of ,front and ,back ,driving-,wheels #if in4 ,total ,weight of ,locomotive in working order #gg1jjj lbs4 ,total ,weight on ,driving-,wheels #ff1jjj lbs4 ,diameter of ,driving-,wheels #eb in4 ,diameter of ,truck-,wheels #cj in4 ,diameter of ,cylinders #ah in4 ,stroke of ,cylinders #bd in4 ,outside ,diameter of smallest ,boiler ,ring #ej in4 ,size of ,grate #ff #cd in4 ,number of ,tubes #afa ,diameter of ,tubes #b in4 ,length of ,tubes #aa ft4 #c in4 ,square ,feet of ,grate surface #af ,square ,feet of ,heating surface in ,fire-,box #ajb4g ,square ,feet of ,heating surface in ,tubes #idh ,total ,feet of ,heating surface #ajea ,exhaust ,nozzles--single or double ,double4 ,diameter of ,nozzle #c to #c in4 ,size of ,steam ,ports #a #af in4 ,size of ,exhaust ,ports #b #af in4 ,throw of ,eccentrics #e in4 ,outside ,lap of ,valve in4 ,inside ,lap of ,valve in4 ,size of ,main ,driving-axle ,journal #g in4 dia4 #h in4 ,size of other ,driving-axle ,journal #g in4 dia4 #h in4 ,size of ,truck-axle ,journal #e in4 dia4 #h in4 ,diameter of ,pump ,plunger #b in4 ,stroke of ,pump ,plunger #bd in4 ,capacity of ,tank #b1bjj gallons4 ,illustration3 ,plate ,,xi4 8,,mogul0 ,,locomotive1 ,,by ,,the ,,baldwin ,,locomotive ,,works1 ,,philadelphia4 ,scale1 in4 #a ft4 ,,plate ,,xii4 ,,dimensions1 ,,weight1 ,,etc41 ,,of 8,,consolidation0 ,,locomotive1 ,,by ,,the ,,danforth ,,locomotive ,,and ,,machine ,,co41 ,,paterson1 ,n4 ,j4 ,gauge of ,road #d ft4 #h in4 ,number of ,driving-,wheels #h ,number of ,front ,truck-,wheels #b ,number of ,back ,truck-,wheels ,none4 ,total ,wheel ,base #bc ft4 #b in4 ,distance between centres of ,front and ,back ,driving-,wheels #ae ft4 #g in4 ,total ,weight of ,locomotive in working order #if1eej lbs4 ,total ,weight on ,driving-,wheels #hf1dcj lbs4 ,diameter of ,driving-,wheels #d ft4 #b in4 ,diameter of ,truck-,wheels #b ft4 #g in4 ,diameter of ,cylinders #bj in4 ,stroke of ,cylinders #bd in4 ,outside ,diameter of smallest ,boiler ,ring #d ft4 #b in4 ,size of ,grate #abj #cd in4 ,number of ,tubes #afe ,diameter of ,tubes #b in4 ,length of ,tubes #ac ft4 #i in4 ,square ,feet of ,grate surface #bi ,square ,feet of ,heating surface in ,fire-,box #aci ,square ,feet of ,heating surface in ,tubes #acgj ,total ,feet of ,heating surface #aeji ,exhaust ,nozzles--single or double ,double ,diameter of ,nozzle #c in4 ,size of ,steam ,ports #a x #ae in4 ,size of ,exhaust ,ports #b #ae in4 ,throw of ,eccentrics #e in4 ,outside ,lap of ,valve in4 ,inside ,lap of ,valve 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,diameter of ,tubes #a in4 ,length of ,tubes #c ft4 ,square ,feet of ,grate surface #e ft4 ,square ,feet of ,heating surface in ,fire-,box #be ft4 ,square ,feet of ,heating surface in ,tubes #abf ft4 ,total ,feet of ,heating surface #aea ft4 ,exhaust ,nozzles--single or double ,double4 ,diameter of ,nozzle #b in4 ,size of ,steam ,ports #f in4 ,size of ,exhaust ,ports #f #b in4 ,throw of ,eccentrics #b in4 ,outside ,lap of ,valve in4 ,inside ,lap of ,valve in4 ,diameter of ,main ,driving-axle ,journal #c in4 ,size of other ,driving-axle ,journal ,size of ,truck-axle ,journal ,diameter of ,pump ,plunger #a in4 ,stroke of ,pump ,plunger #aj in4 ,capacity of ,tank #aji gallons4 ,illustration3 ,plate ,,xix4 ,,locomotive ,,for ,,the ,,new ,,york ,,elevated ,,railroad1 ,,designed ,,by ,d4 ,w4 ,,wyman1 ,,superintendent4 ,scale1 in4 #a ft4 ,appendix ,i4 ---------------------------------------- ------------------------ ,,properties ,,of ,,saturated ,,steam4 ---------------------------------------- ------------------- ,relative ,total volume of pressure ,weight the steam per sq4 ,sensible ,total heat of one compared inch1 temperature in degrees cubic with the measured ,pressure in from zero foot water from from a above the ,fahrenheit of of which it vacuum4atmosphere4 degrees4 ,fahrenheit4 steam4was raised4 ---------------------------------------- ------------------- ,lb4 ,lb4 ,deg4 ,deg4 ,lb4 #a 44 #ajb4a #aadd4e 4#jjcj #bjehb #b 44 #abf4c #aaea4g 4#jjeh #ajgba #c 44 #ada4f #aaef4f 4#jjhe #gcbb #d 44 #aec4a #aafj4a 4#jaab #eehc #e 44 #afb4c #aafb4i 4#jach #debg #f 44 #agj4b #aafe4c 4#jafc #chac #g 44 #agf4i #aafg4c 4#jahi #cbih #h 44 #ahb4i #aafi4b 4#jbad #biji #i 44 #ahh4c #aagj4h 4#jbci #bfjd #aj 44 #aic4c #aagb4c 4#jbfd #bceh #aa 44 #aig4h #aagc4g 4#jbhi #baeg #ab 44 #bjb4j #aage4j 4#jcad #aihf #ac 44 #bje4i #aagf4b 4#jcch #ahdb #ad 44 #bji4f #aagg4c 4#jcfb #agbj #ad4g #j4 #bab4j #aagh4a 4#jchj #afdb #ae 4#c #bac4a #aagh4d 4#jchg #afaj 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4#cceg #ahg #adi #acd4c #ceg4h #abbb4e 4#ccgg #ahf #aej #ace4c #ceh4c #abbb4g 4#ccig #ahd #aee #adj4c #cfa4j #abbc4e 4#cejj #agi #afj #ade4c #cfc4d #abbd4b 4#cfjg #agd #afe #aej4c #cff4j #abbd4i 4#cgad #afi #agj #aee4c #cfh4b #abbe4g 4#chba #afd #age #afj4c #cgj4h #abbf4d 4#cibh #aei #ahj #afe4c #cgb4i #abbg4a 4#djce #aee #ahe #agj4c #cge4c #abbg4h 4#dadb #aea #aij #age4c #cgg4e #abbh4e 4#dbej #adh #aie #ahj4c #cgi4g #abbi4b 4#dceg #add #bjj #ahe4c #cha4g #abbi4h 4#ddfd #ada #baj #aie4c #chf4j #abca4a 4#dffh #ace #bbj #bje4c #chi4i #abcb4c 4#dhgb #abi #bcj #bae4c #cic4h #abcc4e 4#ejgb #abc #bdj #bbe4c #cig4e #abcd4f 4#ebgj #aai #bej #bce4c #dja4a #abce4g 4#edga #aad #bfj #bde4c #djd4e #abcf4h 4#efgj #aaj #bgj #bee4c #djg4i #abcg4h 4#ehga #ajf #bhj #bfe4c #daa4b #abch4h 4#fjgj #ajb #bij #bge4c #dad4d #abci4h 4#fbfh #ii #cjj #bhe4c #dag4e #abdj4g 4#fdfi #if ,appendix ,,ii4 ------------ ,table of ,hyperbolic ,logarithms4 ----------- ,loga- ,num4rithms4 ----------- #a4ja 4#jjii #a4jb 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#a4fijj #e4dc #a4fiai #e4dd #a4ficg #e4de #a4fief #e4df #a4figd #e4dg #a4fiib #e4dh #a4gjaa #e4di #a4gjbi #e4ej #a4gjdg #e4ea #a4gjfe #e4eb #a4gjhc #e4ec #a4gaja #e4ed #a4gaai #e4ee #a4gacg #e4ef #a4gaee #e4eg #a4gagc #e4eh #a4gaia #e4ei #a4gbji #e4fj #a4gbbg #e4fa #a4gbde #e4fb #a4gbfc #e4fc #a4gbha #e4fd #a4gbih #e4fe #a4gcaf #e4ff #a4gccd #e4fg #a4gcea #e4fh #a4gcfi #e4fi #a4gchg #e4gj #a4gdjd #e4ga #a4gdbb #e4gb #a4gdci #e4gc #a4gdeg #e4gd #a4gdgd #e4ge #a4gdia #e4gf #a4geji #e4gg #a4gebf #e4gh #a4gedd #e4gi #a4gefa #e4hj #a4gegh #e4ha #a4geie #e4hb #a4gfac #e4hc #a4gfcj #e4hd #a4gfdg #e4he #a4gffd #e4hf #a4gfha #e4hg #a4gfih #e4hh #a4ggae #e4hi #a4ggcb #e4ij #a4ggdi #e4ia #a4ggff #e4ib #a4gghc #e4ic #a4ghjj #e4id #a4ghag #e4ie #a4ghcc #e4if #a4ghej #e4ig #a4ghfg #e4ih #a4ghhd #e4ii #a4gijj #f4jj #a4giag #f4ja #a4gicd #f4jb #a4giej #f4jc #a4gifg #f4jd #a4gihd #f4je #a4hjjj #f4jf #a4hjag #f4jg #a4hjcc #f4jh #a4hjej #f4ji #a4hjff #f4aj #a4hjhb #f4aa #a4hjii #f4ab #a4haae #f4ac #a4haca #f4ad #a4hadh #f4ae #a4hafd #f4af #a4hahj #f4ag #a4haif #f4ah #a4hbac #f4ai #a4hbbi #f4bj #a4hbde #f4ba #a4hbfa #f4bb #a4hbgg #f4bc #a4hbic #f4bd #a4hcji #f4be #a4hcbe #f4bf #a4hcda #f4bg #a4hceg #f4bh #a4hcgc #f4bi #a4hchi #f4cj #a4hdje #f4ca #a4hdba #f4cb #a4hdcg #f4cc #a4hdec #f4cd #a4hdfh #f4ce #a4hdhd #f4cf #a4hejj #f4cg #a4heae #f4ch #a4heca #f4ci #a4hedg #f4dj #a4hefb ----------- ,appendix ,,iii4 ,table ,showing the ,value and ,properties of ,various ,kinds of ,coal4 ---------------------------------------- ---------------------- ,cubic ,weight feet per of space ,volatile cubic requiredcombustible foot by to stow matter in ,,designation ,,of ,,coal4 experiment a ton #ajj parts ---------------------------------------- ---------------------- ,beaver ,meadow1 slope ,no4 #c ,pa4 #ed4ic #dj4gh #b4ch ,beaver ,meadow1 slope ,no4 #e ,pa4 #ef4ai #ci4hf #b4ff ,forest improvement ,pa4 #ec4ff #da4ge #c4jg ,peach ,mountain ,pa4 #ec4g #da4fd #b4if ,lehigh ,pa4 #ee4cb #dj4ej #e4bh ,lackawanna ,pa4 #dh4hi #de4hb #c4ia ,lyken's ,valley ,pa4 #dh4ef #df4ac #f4hh ,beaver ,meadow 7,navy ,yard7 ,pa4 #ee4jh #dj4fe --- ,natural coke of ,virginia ,va4 #df4fd #dh4jc #ab4dd ,coke of ,midlothian coal ,va4 #cb4gj #fh4ej --- ,coke of ,neff's 7,cumberland7 coal ,md4 #ca4eg #gj4ie --- ,mixture ,cumb4 and ,beaver ,meadow #ed4bi #da4bf --- ,mixture ,cumb4 and ,beaver ,meadow #ed4ea #da4ji --- ,new ,york and ,maryland ,mining ,company's ,md4 #ec4gj #da4ga #ab4ca ,neff's ,cumberland ,md4 #ed4bi #da4bf #ab4fg ,easby's 8coal in store0 ,md4 #ec4dg #da4ij #ad4ih ,atkinson ,templeman's ,md4 #eb4ib #db4cc #ae4ec ,easby ,smith's ,md4 #ea4af #dc4gh #ae4eb ,cumberland 7,navy ,yard7 ,md4 #ec4bi #db4jd #ad4hg ,dauphin ,susquehanna ,pa4 #ej4ed #dd4cb #ac4hb ,blossburg ,pa4 #ec4je #db4bb #ad4gh ,lycoming ,creek ,pa4 #ee4ch #dj4de #ac4hd ,quin's ,run ,pa4 #ej4cd #dd4ej #ag4ig ,karthaus ,pa4 #eb4ed #db4fc #ai4ec ,cambria ,county ,pa4 #ec4df #da4ij #bj4eb ,barr's ,deep ,run ,va4 #ec4ag #db4ac #ai4gh ,crouch ,snead's ,va4 #ec4ei #da4hj #bd4ch ,midlothian 7#ijj feet shaft7 ,va4 #ej4eb #dd4cd #bg4bh ,creek ,company's coal ,va4 #df4ej #dh4ag #cb4dg ,clover ,hill ,va4 #de4di #di4be #cb4ba ,chesterfield ,mining ,company's ,va4 #de4ee #di4ah #cb4fc ,midlothian 7average7 ,va4 #ed4jd #da4de #bi4hf ,tippecanoe ,va4 #de4aj #di4fg #cd4ed ,midlothian 7new shaft7 ,va4 #dg4ij #df4gf #ce4gg ,midlothian 7screened7 ,va4 #de4gb #dh4ii #cd4gj ,midlothian 7,navy ,yard7 ,va4 #ed4dg #da4ac #bi4ab ,pictou 7from ,new ,york7 ,n4 ,s4 #ec4ee #da4hc #bg4hc ,sidney ,n4 ,s4 #dg4dd #dg4bb #bc4ha ,pictou 7,cunards7 ,n4 ,s4 #di4be #de4dh #be4ig ,liverpool ,eng4 #dg4hh #df4gh #ci4if ,newcastle ,eng4 #ej4hb #dd4jh #ce4hc ,scotch ,scotland #ea4ji #dc4hd #ci4ai ,pittsburg ,pa4 #df4ha #dg4he #cf4gf ,cannelton ,ind4 #dg4fe #dg4ja #cc4ii ,dry ,pine ,wood #ba4ja #ajf4jb --- ---------------------------------------- ---------------------- ---------------------------------------- ----------------------- ,total waste in the ,pounds state of ,fixed,earthy of steamashes and carbonmatter to #a clinker in #ajj;in #ajj of coal from #ajj ,,designation ,,of ,,coal4 parts partsfrom #bab of coal ---------------------------------------- ----------------------- ,beaver ,meadow1 slope ,no4 #c ,pa4 #hh4id #g4aa #i4ba #aa4if ,beaver ,meadow1 slope ,no4 #e ,pa4 #ia4d #e4ae #i4hh #f4gd ,forest improvement ,pa4 #ij4ge #d4da #aj4jf #f4ig ,peach ,mountain ,pa4 #hi4jb #f4ac #aj4aa #f4ig ,lehigh ,pa4 #hi4ae #e4ef #h4ic #g4bb ,lackawanna ,pa4 #hg4gd #f4ce #i4gi #h4ic ,lyken's ,valley ,pa4 #hc4hd #i4be #i4df #ab4bd ,beaver ,meadow 7,navy ,yard7 ,pa4 --- #h4aj #i4jh #h4aj ,natural coke of ,virginia ,va4 #ge4jh #aa4hc #h4dg #ah4df ,coke of ,midlothian coal ,va4 --- #af4ee #h4fc #af4ed ,coke of ,neff's 7,cumberland7 coal ,md4 --- #ac4cd #i4jj #ac4cd ,mixture ,cumb4 and ,beaver ,meadow --- #h4hh #h4hf #h4hh ,mixture ,cumb4 and ,beaver ,meadow --- #h4ah #i4ah #h4ah ,new ,york and ,maryland ,mining ,company's ,md4 #gc4ej #ab4dj #i4gh #ab4ga ,neff's ,cumberland ,md4 #gd4ec #aj4cd #i4dd #aj4if ,easby's 8coal in store0 ,md4 #gf4bf #h4jh #aj4jb #h4ch ,atkinson ,templeman's ,md4 #gf4fi #g4cc #aj4gj #g4if ,easby ,smith's ,md4 #gd4bi #i4cj #i4if #i4fi ,cumberland 7,navy ,yard7 ,md4 #gj4he #ad4ih --- #ad4ec ,dauphin ,susquehanna ,pa4 #gd4bd #aa4di #i4cd #af4cf ,blossburg ,pa4 #gc4aa #aj4gg #i4gb #aa4bj ,lycoming ,creek ,pa4 #ga4ec #ac4if #h4ia #af4ib ,quin's ,run ,pa4 #gb4gi #h4da #aj4bg #h4id ,karthaus ,pa4 #gc4gg #g4jj #i4ji #g4hi ,cambria ,county ,pa4 #fi4cg #i4ae #i4bd #i4ge ,barr's ,deep ,run ,va4 #fg4if #aj4dg #i4jb #aa4jg ,crouch ,snead's ,va4 #ei4ih #ad4bh #h4cd #ad4cd ,midlothian 7#ijj feet shaft7 ,va4 #fa4jh #aj4dg #h4eh #aj4gj ,creek ,company's coal ,va4 #fj4cj #h4eg #h4db #h4fd ,clover ,hill ,va4 #ef4hc #aj4ac #g4fg #aj4fj ,chesterfield ,mining ,company's ,va4 #eh4gi #h4fc #i4jj #i4jg ,midlothian 7average7 ,va4 #ec4ja #ad4gd #h4bi #ad4hc ,tippecanoe ,va4 #ed4fb #i4cg #g4ge #i4gb ,midlothian 7new shaft7 ,va4 #ef4dj #i4dd #h4ge #aj4bf ,midlothian 7screened7 ,va4 #ed4jf #i4ff #h4id #aj4bg ,midlothian 7,navy ,yard7 ,va4 #ef4aa #ad4ad --- --- ,pictou 7from ,new ,york7 ,n4 ,s4 #ef4ih #ac4ci #h4da #ac4cg ,sidney ,n4 ,s4 #fg4eg #e4di #g4ii #f4ja ,pictou 7,cunards7 ,n4 ,s4 #fj4gd #ab4ea #h4dh #ab4jf ,liverpool ,eng4 #ed4ij #d4fb #g4dh #e4jd ,newcastle ,eng4 #eg4jj #e4dj #h4ff #e4fh ,scotch ,scotland #dh4ha #i4cd #f4ie #aj4aj ,pittsburg ,pa4 #ed4ic #g4jg #h4bj #h4be ,cannelton ,ind4 #eh4dd #d4ig #g4cd #e4ab ,dry ,pine ,wood --- #j4cj #d4fi #j4cj ---------------------------------------- ----------------------- ---------------------------------------- --------------------- ,weight,av4 weight of in lbs4 clinkerof unburnt ,steam alone coke left from #bab from on grate from #a of #ajj ofafter eachcombustible ,,designation ,,of ,,coal4 coal experiment matter ---------------------------------------- --------------------- ,beaver ,meadow1 slope ,no4 #c ,pa4 #a4ja #aab4d #aj4dfb ,beaver ,meadow1 slope ,no4 #e ,pa4 #j4fj #fa4b #aj4eib ,forest improvement ,pa4 #j4ha #dj4b #aj4hjg ,peach ,mountain ,pa4 #c4jc #bf4f #aj4hga ,lehigh ,pa4 #a4jh #cf4a #i4fbf ,lackawanna ,pa4 #a4bd #eg4b #aj4gfd ,lyken's ,valley ,pa4 #d4dj #ah4j #aj4ghh ,beaver ,meadow 7,navy ,yard7 ,pa4 #a4dj #ajg4a #i4hha ,natural coke of ,virginia ,va4 #e4ca #fj4i #aj4chi ,coke of ,midlothian coal ,va4 #aj4ea #ec4b #aj4cdc ,coke of ,neff's 7,cumberland7 coal ,md4 #c4ee #dc4g #aj4cha ,mixture ,cumb4 and ,beaver ,meadow #d4ia #i4e #i4gbe ,mixture ,cumb4 and ,beaver ,meadow #c4ji #af4j #i4iig ,new ,york and ,maryland ,mining ,company's ,md4 #e4dc #aj4a #aa4bjh ,neff's ,cumberland ,md4 #d4ec #f4a #aj4fjd ,easby's 8coal in store0 ,md4 #a4cc #ah4b #aj4ice ,atkinson ,templeman's ,md4 #b4ab #e4a #aa4fbd ,easby ,smith's ,md4 #c4jd #e4c #aa4jcd ,cumberland 7,navy ,yard7 ,md4 #b4bi #ac4e --- ,dauphin ,susquehanna ,pa4 #c4ej #bc4g #aa4aga ,blossburg ,pa4 #c4dj #ac4g #aj4ief ,lycoming ,creek ,pa4 #c4bf #df4b #aj4gbd ,quin's ,run ,pa4 #a4ca #ad4g #aa4bge ,karthaus ,pa4 #c4ff #eb4e #i4hhg ,cambria ,county ,pa4 #c4dh #ad4h #aj4bci ,barr's ,deep ,run ,va4 #d4gh #f4d #aj4adb ,crouch ,snead's ,va4 #e4cg #f4j #i4gdj ,midlothian 7#ijj feet shaft7 ,va4 #f4dg #e4i #i4faa ,creek ,company's coal ,va4 #d4da #aj4e #i4baa ,clover ,hill ,va4 #c4hf #aa4e #h4ehh ,chesterfield ,mining ,company's ,va4 #d4ai #aj4e #i4hif ,midlothian 7average7 ,va4 #h4hb #f4d #i4gda ,tippecanoe ,va4 #d4jc #aa4b #h4ehc ,midlothian 7new shaft7 ,va4 #d4ba #ag4a #i4gea ,midlothian 7screened7 ,va4 #c4cc #ad4h #i4igj ,midlothian 7,navy ,yard7 ,va4 #d4db #dc4b --- ,pictou 7from ,new ,york7 ,n4 ,s4 #f4ac #e4g #i4gaj ,sidney ,n4 ,s4 #b4bd #e4i #h4dig ,pictou 7,cunards7 ,n4 ,s4 #f4ai #c4g #i4fdh ,liverpool ,eng4 #a4hf #aa4a #h4bee ,newcastle ,eng4 #c4ad #aj4g #i4agh ,scotch ,scotland #e4fc #e4g #g4gai ,pittsburg ,pa4 #j4id #i4i #h4idb ,cannelton ,ind4 #a4fd #f4d #g4gcd ,dry ,pine ,wood --- --- #d4gjg ---------------------------------------- --------------------- ,appendix ,,iv4 ,table of ,resistances of ,railroad ,trains with ,different ,grades and ,speeds4 ---------------------------------------- ----------------- ,resistance ,total due to resistance1 ascent alone lbs4 ,rise of in lbs4 per ton1 #aj #ae #bj #be #cj gradient1 per ton at rate ofmilesmilesmilesmilesmiles feet per7#b1jjj lbs47 #e miles per per per per per mile4 of train4 per hour4 hour4hour4hour4hour4hour4 ---------------------------------------- ----------------- #j #f4a #f4f #g4c #h4c #i4f #aa4b #e #a4h #g4i #h4d #i4a #aj4a #aa4d #ac4j #aj #c4g #i4h #aj4c #aa4j #ab4j #ac4d #ad4i #ae #e4f #aa4g #ab4b #ab4i #ac4i #ae4b #af4h #bj #g4e #ac4f #ad4a #ad4h #ae4h #ag4a #ah4g #be #i4d #ae4e #af4j #af4g #ag4g #ai4j #bj4f #cj #aa4c #ag4d #ag4i #ah4f #ai4f #ba4i #bb4e #ce #ac4b #ai4c #ai4h #bj4e #ba4e #bb4h #bd4d #dj #ae4a #ba4b #ba4g #bb4d #bc4d #bd4g #bf4c #de #ag4j #bc4a #bc4f #bd4c #be4c #bf4f #bh4b #ej #ah4i #be4j #be4e #bf4b #bg4b #bh4e #cj4a #fj #bb4g #bh4h #bi4c #cj4j #ca4j #cb4c #ch4i #gj #bf4e #cb4f #cc4a #cc4h #cd4h #cf4a #cg4g #hj #cj4c #cf4d #cf4i #cg4f #ch4f #ci4i #dj4e #ij #cd4j #da4j #dj4f #da4c #db4c #dc4f #de4b #ajj #cg4h #dc4i #dd4d #de4a #df4a #dg4d #di4j #aaj #da4f #dg4g #dh4b #dh4i #di4i #ea4b #eb4h #abj #de4d #ea4e #eb4j #eb4g #ec4g #ee4j #ef4f #acj #di4b #ee4c #ee4h #ef4e #eg4e #eh4h #fj4d #adj #ec4j #ei4a #ei4f #fj4c #fa4c #fb4f #fd4b #aej #ef4h #fb4i #fc4d #fd4a #fe4a #ff4d #fh4j #afj #fj4f #ff4g #fg4b #fg4i #fh4i #gj4b #ga4h #agj #fd4c #gj4d #gj4i #ga4f #gb4f #gc4i #ge4e #ahj #fh4a #gd4b #gd4g #ge4d #gf4d #gg4g #gi4c #aij #ga4i #gh4j #gh4e #gi4b #hj4b #ha4e #hc4a #bjj #ge4g #ha4h #hb4c #hc4j #hd4j #he4c #hf4i #baj #gi4e #he4f #hf4a #hf4h #hg4h #hi4a #ij4g #bbj #hc4c #hi4d #hi4i #ij4f #ia4f #ib4i #id4e #bcj #hg4a #ic4b #ic4g #id4d #ie4d #if4g #ih4c #bdj #ij4h #if4i #ig4d #ih4a #ii4aajj4dajb4j #bej #id4f #ajj4g #aja4baja4iajb4iajc4baje4h #bfj #ih4d #ajd4e #aje4jaje4gajf4gajg4jajh4f #bgj #ajb4b #ajh4c #ajh4haji4eaaj4eaaa4haac4d #bhj #ajf4j #aab4a #aab4faac4caad4caae4faag4b #bij #aji4h #aae4i #aaf4daag4aaah4aaai4daba4j #cjj #aac4f #aai4g #abj4babj4iaba4iabc4babd4h ---------------------------------------- ----------------- ---------------------------------------- ----------- ,resistance due to ascent alone ,rise of in lbs4 #ce #dj #de #ej #fj #gj gradient1 per ton milesmilesmilesmilesmilesmiles feet per7#b1jjj lbs47 per per per per per per mile4 of train4 hour4hour4hour4hour4hour4hour4 ---------------------------------------- ----------- #j #ac4a #ae4c #ag4h #bj4f #bg4j #cd4f #e #a4h #ad4i #ag4a #ai4f #bb4d #bh4h #cf4d #aj #c4g #af4h #ai4j #ba4e #bd4c #cj4g #ch4c #ae #e4f #ah4g #ba4i #bd4d #bg4b #cc4f #da4b #bj #g4e #bj4f #bb4h #be4c #bh4a #cd4e #db4a #be #i4d #bb4e #bd4g #bg4b #ca4j #cg4d #de4j #cj #aa4c #bd4d #bf4f #bi4a #ca4i #ch4c #de4i #ce #ac4b #bf4c #bh4e #ca4j #cc4h #dj4b #dg4h #dj #ae4a #bh4b #cj4d #cb4i #ce4g #db4a #di4g #de #ag4j #cj4a #cb4c #cd4h #cg4f #dd4j #ea4f #ej #ah4i #cb4j #cd4b #cf4g #ci4e #de4i #ec4e #fj #bb4g #ce4h #ch4j #dj4e #dc4e #di4i #eg4e #gj #bf4e #ci4f #da4h #dd4c #dg4a #ec4e #fa4a #hj #cj4c #db4d #dd4f #dg4a #di4i #ef4c #fc4i #ij #cd4j #dg4a #di4c #ea4h #ed4f #fa4j #fh4f #ajj #cg4h #ea4i #ed4a #ef4f #ei4d #fe4h #gc4d #aaj #da4f #ed4g #ef4i #ei4d #fb4b #fh4f #gf4b #abj #de4d #eh4e #fj4g #fc4b #ff4j #gb4d #hj4j #acj #di4b #fb4c #fd4e #fg4j #fi4h #gf4b #hc4h #adj #ec4j #ff4a #fh4c #gj4h #gc4f #hj4j #hg4f #aej #ef4h #fi4i #gb4a #gd4f #gg4d #hc4h #ia4d #afj #fj4f #gc4g #ge4i #gh4d #ha4b #hg4f #ie4b #agj #fd4c #gg4d #gi4f #hb4a #hd4i #ia4c #ih4i #ahj #fh4a #ha4b #hc4d #he4i #hh4g #ie4aajb4g #aij #ga4i #he4j #hg4b #hi4g #ib4e #ih4iajf4e #bjj #ge4g #hh4h #ia4j #ic4e #if4cajb4gaaj4c #baj #gi4e #ib4f #id4h #ig4cajj4aajf4eaad4a #bbj #hc4c #if4d #ih4faja4aajc4iaaj4caag4f #bcj #hg4a #ajj4bajb4dajd4iajg4gaad4aaba4g #bdj #ij4h #ajc4iajf4aajh4faaa4daag4habe4d #bej #id4f #ajg4gaji4iaab4daae4baba4fabi4b #bfj #ih4d #aaj4eaab4gaae4baah4jabd4dacb4j #bgj #ajb4b #aae4caag4eabj4jabb4habi4bacf4h #bhj #ajf4j #aai4aaba4cabc4habf4facc4jadj4f #bij #aji4h #abb4iabe4aabg4facj4dacf4hadd4d #cjj #aac4f #abf4gabh4iaca4dacd4badj4fadh4b ---------------------------------------- ----------- ,,index4 ,,the ,,figures ,,below ,,refer ,,to ,,the ,,numbers ,,of ,,the ,,pages4 ,absolute pressure1 #ac4 ,accidents to locomotives1 #eji4 ,accidents and injuries to persons1 #ecc2 danger from1 #ece4 ,actual energy1 #bd4 ,adhesion1 #fb1 #cai2 amount of1 #cbj2 proportion of to resistance1 #dab4 ,adhesive weight1 #cba4 ,admission1 depends on1 #bbb2 how affected1 #bee2 how equalized1 #bdi2 of steam1 #cj2 period of1 #bdi4 ,admission line1 #bcf1 #bcg4 ,air1 admission of to fire-box1 #chj2 control of supply of1 #chd2 forces of1 #h2 method of admitting to the fire-box1 #chb2 pressure of1 #h1 #i2 quantity necessary for combustion1 #cha1 #chh2 quantity needed for dilution of gases1 #chi2 quantity to be admitted through the grate and above the fire1 #cia2 weight of1 #h4 ,air chamber1 #aag4 ,alarm check1 #abf4 ,algebra1 x4 ,algebraic symbols1 x4 ,allen valve1 #bbd4 ,american locomotive1 #dbi2 engraving of1 #eee1 #eeg1 #eei1 #efa1 #efc4 ,american ,railway ,master ,mechanics' ,association1 #bfj1 #bhh4 ,angular advance1 #bea4 ,animal oil1 #ejd4 ,anthracite coal1 #aab1 #aeb1 #djc2 firing with1 #ejc4 ,aquafortis1 #cfh4 ,argand-burner1 #ccf4 ,arterial bleeding1 #ecf4 ,artery1 #ecf2 injury to1 #ecg1 #eci2 position of1 #ecg4 ,ash-pan1 #fg2 construction of1 #ha4 ,ash-pan dampers1 #ha2 operation of1 #aec4 ,atmospheric line1 #dh4 ,automatic brakes1 #ddb2 management of1 #die4 ,axle1 adjustment of1 #dge2 breaking of1 #eji1 #ebc2 how made to assume a radical position1 #bgh1 #bhb2 main driving1 #fc4 ,axle box1 arrangement of1 #bif2 bearing of1 #bij2 driving1 #bij2 for tenders1 #cee2 wear of1 #big4 ,babbitt's metal1 #agc1 #age1 #ahj4 ,back elevation1 xiv4 ,back pressure1 #ef1 #afc2 line of1 #bcf1 #bdc4 ,back view1 xiv4 ,backward motion or gear1 #ahg4 ,baldwin ,locomotive ,works1 #dbi2 locomotive by1 #eee1 #efe1 #efg4 ,ball joint1 #afj4 ,bearings1 brass1 #agg2 for driving axles1 #bij2 for tender axles1 #ced2 for truck axles1 #bib2 proportions of1 #cfb2 wear of1 #agi4 ,bearing-bars1 #aeb4 ,bed-casting1 #afd4 ,bed-plate1 #adf4 ,bell1 #cce2 use of1 #dgi4 ,bissell truck1 #dcb4 ,bituminous coal1 #cfh2 composition of1 #cfi1 #chh2 use of1 #ejc4 ,blast orifice1 #ga2 7see also exhaust nozzle74 ,bleeding1 danger from1 #ece2 stopping of1 #ecg1 #edj4 ,blower1 #adi2 use of1 #dhj4 ,blower cock1 #adi4 ,blow-off cock1 #adh4 ,block1 link1 #ahe2 7see link block74 ,boiler1 #ff1 #ga2 advantages of large size1 #dbb2 calculations of1 #dai2 capacity of1 #ga1 #dah2 cleaning of1 #adg1 #eje2 emptying of1 #adg2 expansion of1 #ij1 #bie1 #dgh2 explosion of1 #eji1 #ead2 feeding of1 #dhc2 filling of1 #ejf2 inspection of1 #dfa2 irregular action of1 #dba2 organs of1 #ff2 operation of1 #dbj2 proportions of1 #dai2 size of1 #dag1 #dbj2 strains on1 #he1 #dgh2 testing of1 #dfa4 ,boiler attachments1 #aae2 examination of1 #dfe4 ,boiler plate1 fastenings of1 #ij2 resistance of1 #ie2 strength of1 #hi1 #ie2 unequal strain on1 #ib4 ,boiler pressure1 #bbc2 difficulty of maintaining in cylinders1 #bbc4 ,boiler seams1 form of1 #ajc2 strength of1 #ic1 #ajf4 ,boiling1 #aj4 ,boiling point1 #aa4 ,bones1 injury to1 #edb4 ,books1 list of1 #eej4 ,boss1 #bjg4 ,boxes1 for driving axles1 #bij2 for tender axles1 #cee2 for truck axles1 #bib4 ,braces1 #hj1 #ajg2 for frames1 #bib2 proportions of1 #ajh4 ,brakes1 continuous train1 #ddb2 for tenders1 #cef2 inspection of1 #dge2 reliance on1 #did4 ,brass bearings1 #agg2 7see bearings74 ,brasses1 #agg4 ,breaking joints1 #agc4 ,bridges1 #ca2 width of1 #bfj4 ,buchanan1 ,william1 see preface1 #djb4 ,bumper-timber1 #bib4 ,bunsen burner1 #cgd4 ,burns1 treatment of1 #edb4 ,bushing1 #agd1 #ahj4 ,butt-joints1 #ajf4 ,cages1 #aaf4 ,candle1 #cge2 flame of1 #cge4 ,carbon1 #cfi1 #cga2 air required for combustion of1 #chh2 total heat of combustion1 #chj4 ,carbonic-acid gas1 #cgh4 ,carbonic dioxide1 #cgh4 ,carbonic oxide1 #cgh4 ,carburetted hydrogen1 #cfi4 ,carrying wheels1 #bfh4 ,cars1 resistance of1 #djf4 ,casing1 for cylinders1 #agj4 ,caulking1 #ajf2 effect of1 #ajg4 ,caulking edge1 #ajf4 ,centre bearing1 #cef2 lubrication of1 #dge4 ,centre of gravity1 calculation for1 #cbi1 #ccj1 #cca4 ,centre-pin1 #bfi1 #bga1 #caf4 ,centre-plate1 lower1 for truck1 #caf2 lubrication of1 #dge2 upper1 #caf4 ,check-chains1 #cdj1 #cej4 ,check-valve1 failure of1 #eji1 #eah2 for injector1 #abj2 for pump1 #aag4 ,chemical element1 #cfe2 combination of1 #cff4 ,chemical equivalent1 #cfg4 ,chilling1 #bia4 ,chimney1 #ff2 construction of1 #aab4 ,clearance1 of piston1 #bba2 effect of1 #bbh2 of valve1 #db4 ,coal1 amount of water evaporated by1 #gc1 #cid2 condition of when put on fire1 #chg2 value and properties of1 #eid4 ,cock1 blower1 #adi2 blow-off1 #adh2 cylinder1 #aga2 feed1 #aai2 frost1 #aai2 gauge1 #acj2 heater1 #adi2 oil1 #afi2 pet1 #aah2 try1 #acj4 ,co-efficient of friction1 #cei4 ,coke1 #cgi2 air needed for combustion of1 #cib4 ,cold weather1 #dif4 ,color blindness1 #dic4 ,collision1 #eji2 prevention of1 #eaj4 ,combustion1 #cfe2 air required for1 #chj1 #chh2 chemical process of1 #cgi2 effect on of enlarging the grate1 #cib2 how explained1 #cgj2 in locomotive fire-box1 #cgg2 intensity of1 #cic2 in tubes1 #chf2 products of1 #cgh2 rate of1 #gc1 #cfe2 total heat of1 #chj1 #cic2 when complete1 #cgc4 ,compression1 #dd1 #bba2 calculation of1 #bdc2 effected by1 #bbh2 effect of1 #bdg2 line or curve of1 #bcf4 ,compressive strain1 #hi4 ,combining tube1 #ca4 ,condensation1 #ag4 ,conduction1 #ah2 of heat through heating surfaces1 #cie4 ,cone1 #aab2 cone of wheel1 effect of1 #bgd1 #bgg2 advantage of1 #bhe4 ,connecting-rod1 #e1 #afd2 angularity of1 #de1 #age2 breaking of1 #eji2 construction of1 #agg2 effect of1 #dd2 inspection of1 #dfg1 #dga2 main1 #agg2 pressure of1 #agd2 wear of1 #agg4 ,consolidation locomotive1 #dcj1 #efi4 ,continuous train brakes1 #ddb4 ,convection1 #aaa1 #aah4 ,counterbalance weights1 7see counterweights47 ,countersunk joint1 #aef4 ,counterweights1 #bhi1 #cbh2 calculation for1 #cbh1 #cca1 #ccc2 construction of1 #ccc4 ,coupling1 breaking of1 #eaj1 #eca2 engine to tender1 #dhj4 ,coupling-pin1 #cej4 ,coupling-rod1 #agg2 why taken down1 #ebc4 ,covering strip1 #ajj1 #ajc4 ,cow-catcher1 #bid1 #cch4 ,crank1 #e1 #fc4 ,crank-pin1 #fd2 breaking of1 #eji1 #ebb2 construction of1 #bhh2 how fastened1 #bhh2 inspection of1 #dfh2 pressure on1 #bdd4 ,creamer's brake1 #ddb4 ,crow-feet1 #ajg4 ,cross-head1 #agd2 accident to1 #eji2 inspection of1 #dga4 ,crossing1 approach to1 #dic1 #eaa4 ,crown-bars1 #hj4 ,crown-sheet1 or crown-plate1 #ge1 #hj4 ,crushing1 #ie1 #ih2 treatment of1 #edb4 ,curve1 degree of1 #daj2 resistance on1 #daj2 running through1 #dhi4 ,curve of compression1 #bcf4 ,curve of expansion1 #bcf4 ,cut-off1 #af1 #da2 advantage of1 #dhc2 effect of link on1 #bag2 effect of throw of eccentric on1 #beb4 ,cushion1 #ch1 #bcj4 ,cylinder1 #afc1 #afd2 breaking of1 #eji1 #eba2 construction of1 #afd2 distance between1 #fi2 inspection of1 #fc2 location of1 #fc2 protection of1 #agj2 size of1 #fi1 #dac4 ,cylinder capacity1 #dad2 calculation for1 #dae1 #daf4 ,cylinder casing1 #agj4 ,cylinder cocks1 #aga2 use of1 #dgi4 ,cylinder-heads1 #afe2 breaking of1 #eba4 ,cylinder-head covers1 #agj4 ,cylinder lagging1 #agj4 ,dampers1 for ash-pan1 #ha1 #aec4 ,danforth ,locomotive and ,machine ,co41 #dbi2 locomotive by1 #eei1 #efi4 ,dangers to which locomotive runners are exposed1 #edd4 ,dead-point1 #e4 ,dead-grate1 #chg4 ,deflector1 for fire-box door1 #djj2 for sparks1 #aab4 ,delivery-tube1 #abj4 ,diaphragm1 #adj4 ,different kinds of locomotives1 #dbg4 ,dilution of gases1 air needed for1 #chi4 ,distribution of steam1 #bbj2 defects of1 #bdh2 effect of1 #bca4 ,distribution of weight1 on driving wheels1 #dac4 ,dome1 #aaj2 location of1 #aaj4 ,double-end tank locomotive1 #ega1 #egc1 #eha4 ,double poppet valve1 #aee4 ,double truck locomotive1 #dce1 #egg1 #egi4 ,draft1 #fg1 #gb4 ,draw-bar1 #ccd4 ,draw-bridge1 approach to1 #dic2 running into1 #eji1 #eaa4 ,drawings1 xiii4 ,drilled holes1 #ib1 #if1 #ih1 #ajc4 ,drilling cars1 #dbg4 ,drip-pipe1 #acb4 ,driving-axle1 breaking of1 #ebc2 main1 #gj2 7see also axle74 ,driving-axle boxes1 #bij2 bearing of1 #bij4 ,driving-wheels1 #gj1 #bfh2 action of1 #cbc2 adhesion of1 #fb1 #cai2 breaking of1 #ebc2 construction of1 #bhe2 distance between1 #fh2 effect of their size on combustion and evaporation1 #dbd2 friction of1 #fb1 #cai2 how fastened1 #bhh2 motion of around curves1 #bhd2 relation between size of and that of boiler1 #dbe2 size of1 #fh1 #dac1 #dbe2 weight on1 #fi4 ,drop-door1 #aec4 ,dry-pipe1 #aaa4 ,duplicate parts1 #dgg4 ,dust guard1 #cef4 ,ebullition1 #aa1 #dhe4 ,eccentric1 #f2 effect of throw of1 #beb1 #bee2 how set1 #ahb1 #ebh2 motion how communicated to valve1 #ahe2 motion same as that of crank1 #ca2 slipping of1 #ebf1 #ebh2 throw of1 #ca1 #bea2 with varying lap1 #beh4 ,eccentric-rod1 #g2 breaking of1 #ebg1 #ebi4 ,eccentric-strap1 #f2 breaking of1 #ebi4 ,effective pressure1 #ad4 ,eight-wheeled ,american locomotive1 #eee1 #eeg1 #eei1 #efa1 #efc4 ,ejector1 #ddf4 ,elasticity1 limit of1 #hi1 #cjb2 of spring1 #cjb4 ,elastic strength1 of spring1 #cjb4 ,elementary substances1 #cfe4 ,energy1 #bb1 #bc2 actual1 #bd1 #bi2 of repulsion1 #bh2 possible or potential1 #bh4 ,endurance1 #ede4 ,equalizing lever1 #cji2 advantages of1 #cac2 breaking of1 #eji1 #ebe2 construction of1 #caj2 distribution of weight by1 #caj2 of truck1 #caf4 ,evaporation1 amount required1 #gb2 latent heat of1 #bf4 ,exhaust of steam1 #cj1 #fg2 how affected by link1 #bag1 #bdi4 ,exhaust line1 #bcf1 #bdb4 ,exhaust-nozzle1 #fh1 #ga4 ,exhaust passage1 #afe4 ,exhaust pipe1 #afb4 ,exhaust-port1 #e2 width of1 #bfj4 ,exhaust steam1 action of1 #ga1 #gb4 ,expander1 #hd4 ,expansion1 #af1 #bba2 advantages of1 #ee1 #fj1 #dhb2 limits of economy1 #fj4 ,expansion clamps1 #bid4 ,expansion curve or line1 #ea4 ,experiments with locomotives1 #dej4 ,explosion of boiler1 #eji2 cause of1 #ead2 prevention of1 #eaf4 ,fairlie engine1 #dce4 ,feed-cock1 #aai1 #adi4 ,final pressure1 #ef1 #dhb4 ,fire1 depth or thickness of1 #chc2 management of1 #ejj2 method of feeding1 #chc2 method of starting1 #dgh4 ,firing1 #dii1 #eja4 ,fire-box1 #ff1 #fg2 construction of1 #ge2 expansion of1 #dgi2 form of1 #cig2 size of1 #fi4 ,fire-brick arch1 #cig4 ,flame1 length of1 #cgf2 nature of1 #cga1 #cge4 ,flange of wheel1 #bgh2 friction of1 #bha4 ,flue1 #ff1 #fg2 arrangement of1 #ha2 bursting or collapse of1 #eji1 #eaf2 fastening of1 #hc4 ,flue expander1 #hd4 ,flutter of water1 #dhg4 ,fly-wheel1 #e4 ,foaming1 #dhd2 cause of1 #dhf2 effect of1 #dhh2 prevention of1 #dhf4 ,follower bolts1 #agb4 ,follower plate1 #agb4 ,foot-board or plate1 #bfa1 #cch2 effect of weight of1 #cci4 ,foot pound1 #bc4 ,force-pump1 #aae4 ,forney locomotive1 #dcd1 #ege4 ,forward motion or gear1 #ahg4 ,four-wheeled locomotive1 #dbh2 disadvantages of1 #dbh2 engraving of1 #eec4 ,frames1 #fe1 #bib2 attachment to the fire-box1 #bie2 breaking of1 #eaj1 #ebf2 fastening of1 #bid4 ,franklin ,institute1 system of screw threads1 #cdb4 ,freezing of water in boiler1 #ejg2 in pumps1 #aai1 #ejg1 #ecb4 ,freight locomotive1 #dbi4 ,freight traffic1 #dbg1 #dbi4 ,friction1 #ceh2 depends on1 #ceh2 co-efficient of1 #cei2 effect of pressure and velocity of surfaces on1 #cfa2 effect of area of surfaces in contact1 #cfd2 law of1 #cfc2 of wheel flanges1 #bha2 of wheels1 #fb1 #cai4 ,front view1 xiv4 ,front elevation1 xiv4 ,frost-bite1 treatment of1 #edc4 ,frost-cock1 #aai4 ,fuel1 value of1 #djd42 waste of1 #cid4 ,fulcrum of driving wheel1 #cab4 ,furnace door1 #fg1 #hj1 #adi4 ,gas1 #cfh2 combustion of1 #cgf4 ,gas-light1 #cga4 ,gauge of road1 #ge4 ,gauge-cocks1 #acj4 ,gibs1 #age4 ,gland1 #agc4 ,glass water-gauge1 #acj2 inspection of1 #dfe4 ,grades1 effect of on water level1 #dia2 resistance on1 #djh2 running on1 #dij4 ,grant ,locomotive ,works1 #dbi2 locomotive by1 #eeg4 ,grate1 #fg1 #gc1 #ha1 #adi2 dead1 #chg2 inspection of1 #dfe2 management of1 #ejd1 #ejf2 rocking1 #aeb2 shaking1 #aeb2 surface1 #dai2 water1 #aeb4 ,grate-bars1 #aej4 ,greenwich ,street ,elevated ,railroad1 #dda4 ,guide-blocks1 #agf4 ,guide-rods or bars1 #afd2 inspection of1 #dfg2 object of1 #agd2 wear of1 #agf4 ,guide-yoke1 #age4 ,half-gear1 #aie4 ,hand-holes1 #adh4 ,hand-rails1 #ccg4 ,head-light1 #ccf2 inspection of1 #dgf2 use of1 #die4 ,heat1 conduction of1 #gd2 convertible into work1 #be2 equivalent of1 #bd2 latent1 #bf2 loss of1 #cie2 mechanical equivalent of1 #bb2 total of1 steam1 #bi1 #ehe2 transmission of1 #cha1 #cie1 #dbc2 waste of1 #ah1 #cie4 ,heater-cocks1 #adi2 use of1 #dhf4 ,heating surface1 #fg2 amount needed1 #gc1 #dai1 #dbj4 ,heat of evaporation or gasification1 #cfi4 ,helper1 #dig4 ,henderson's brake1 #ddb4 ,hinkley ,locomotive ,works1 #dbi2 locomotive by1 #eec1 #efc4 ,hood for fire-box door1 #djj4 ,horizontal section1 xiv4 ,hose1 #cej4 ,hudson ,river ,railroad1 locomotives used on1 #ddj4 ,hydrogen1 #cfi1 #cga2 air required for combustion of1 #chh4 ,hyperbolic curve1 #ea1 #bcg4 ,hyperbolic logarithms1 #ed2 table of1 #eij4 ,hyponitrous acid1 #cfh4 ,igniting temperature1 #cgj1 #cgf2 of coal gas1 #chg4 ,incrustating substances1 #ded4 ,indicator1 steam1 #dg1 #bca2 method of attaching1 #bcd4 ,indicator1 diagram1 #ea1 #bcc2 form of1 #bce1 #bdj1 #bda1 #bdg4 ,induced current1 #cgd4 ,initial pressure1 #fj4 ,injector1 #abj2 action of1 #abj2 action of fixed nozzle injector1 #abc2 action of hot water on1 #abc2 fixed nozzle1 #abj2 failure of1 #eji1 #eah2 inspection of1 #dfe2 location of1 #abg2 self-regulating1 #abd4 ,injuries to persons1 #ecc4 ,insensibility1 treatment of1 #eda4 ,inside pipe1 #aac4 ,inspection of locomotives1 #dfa4 ,intensity of combustion1 #cic4 ,internal disturbing forces1 #cbh4 ,introduction1 ix4 ,inverted plane1 xv4 ,jauriet1 ,c4 ,f42 water tables1 #cii4 ,jaws1 #bib4 ,johnson1 ,walter ,b41 experiments on coal1 #dje4 ,journal1 #agg2 effect of increased diameter1 #cfb2 heating of1 #ejd2 oiling of1 #agi2 of driving axle1 #bij2 of truck axles1 #bib4 ,journal bearing1 of driving axle1 #bij2 of tender axles1 #cea2 of truck axles1 #ced4 ,keys1 #agi4 ,lagging1 #aaa2 for cylinders1 #afi4 ,lamp1 #cgc2 for head-light1 #ccf1 #cgf4 ,lap1 #dj1 #bea2 inside1 #dj2 effect of1 #da2 outside1 #dj2 effect of1 #da1 #dd2 effect of reducing1 #bee2 effect of varying1 #beh4 ,latent heat1 #bf2 of evaporation1 #bf1 #bi4 ,lateral motion1 #cag1 #dcj4 ,laughing gas1 #cfh4 ,lead1 #ch1 #bbj1 #bdi1 #bec2 cause of1 #bah2 effect of1 #dd2 how affected by link1 #bah2 how equalized1 #bdi2 inside1 #ch2 necessity for1 #bba4 ,lift of pump valves1 #aag4 ,lifting arm1 #ff2 breaking of1 #ebi4 ,lifting shaft1 #ahe2 breaking of1 #ecj2 position of1 #bej4 ,limit of elasticity1 #hi2 of spring1 #cjb4 ,line and line1 #bcg4 ,linear advance1 #beb4 ,line of back-pressure1 #bcf1 #bdc4 ,line of compression1 #bcf4 ,line of expansion1 #bcf4 ,liners1 #age4 ,link1 #ff1 #ahe2 motion of1 #ahi2 radius of1 #bjj4 ,link-block1 #ahe4 ,link-hanger1 #ahe1 #bej2 breaking of1 #ebi4 ,link motion1 #aha1 #aif1 #bdh4 ,link-saddle1 #ahg2 breaking of1 #ebi4 ,list of books1 #eej4 ,live steam1 #bbi4 ,locomotive1 #fb2 advance of1 #cbc2 capacity of1 #dba2 cleaning and repairing of1 #eje2 cost of operating1 #ddh2 different kinds1 #dbg2 dimensions of1 #fh1 #dbi2 escape of1 #eji1 #eaa2 experiments with1 #dej2 general description of1 #fb2 how turned around1 #dee2 inspection of1 #dfa2 list of parts of1 #fi2 number of miles run to a ton of coal1 #ddi2 principal parts of1 #fb2 proportions of1 #dab2 resistance of1 #fb2 speed of1 #dai2 starting of1 #dhj2 weight of1 #fg4 ,longitudinal section1 xv4 ,lost motion1 #ahj4 ,loughridge's brake1 #ddb4 ,lubricant1 #cfj2 manner of applying1 #cfj4 ,lubrication1 #ceh2 effect of pressure and velocity of surfaces on1 #cfa2 method of1 #dgg4 ,man-hole1 #cdi4 ,mason ,machine ,works1 #dbi1 #dcf2 locomotive by1 #efa1 #egg1 #egi4 ,mason1 ,william1 #dce4 ,master ,mechanics' ,association1 #bfj1 #bhh4 ,mechanical equivalent of heat1 #bb4 ,metropolitan railroads1 #dbg1 #dcg2 locomotives for1 #dcf1 #dch1 #ddj4 ,mid-gear1 #aie4 ,miles run to ton of coal1 #ddi4 ,mineral oil1 #ejd4 ,miscellaneous1 #cce4 ,model of valve-gear1 #bjd4 ,modulus of propulsion1 #dae4 ,mogul locomotive1 #dcj1 #efg4 ,molecular activity1 #cgf4 ,momentum of piston1 #bcj1 #bdd2 creates resistance to turning of crank1 #bdf4 ,motion1 reciprocating1 #e2 rotary1 #e4 ,motion curves1 #cd1 #aif2 how drawn1 #aig1 #bjd1 #bjh4 ,motion diagram1 #bac1 #bad4 ,mud-drum1 #adh4 ,mud-holes1 #adh4 ,new ,york elevated railroad1 #dda2 locomotive for1 #ehc4 ,nitric acid1 #cfh4 ,nitrogen1 #cfh4 ,nitrous acid1 #cfh4 ,nitrous oxide1 #cfh4 ,nuts1 #cda2 proportions of1 #cdh4 ,oil1 #cfj2 animal1 #ejd2 manner of applying1 #cfj2 mineral1 #ejd4 ,oil boxes1 for tender1 #ced4 ,oil cellars1 #agi1 #bij4 ,oil-cock1 #afi4 ,oil-cup1 #agf4 ,open-road1 #dbh2 running on1 #dhi4 ,operating locomotives1 cost of1 #ddh4 ,outside shell of fire-box1 #ge4 ,overflow1 #abj4 ,overflow-nozzle1 #aba4 ,oxalate of ammonia1 #ded4 ,oxygen1 #cfh1 #cgj4 ,packing1 #agc4 ,packing-bolts1 #agc4 ,packing-nuts1 #acb1 #agc4 ,packing-rings1 #agb2 inspection of1 #dfh2 setting out1 #dfi4 ,packing-springs1 #agb4 ,parabolic reflector1 #ccg4 ,parallel motion1 #bcc4 ,parallel-rods1 #agg4 ,passenger traffic1 #dbg2 locomotive for1 #dcf4 ,perforated pipe1 #dhh4 ,performance and cost of operating locomotives1 #ddh4 ,periods of distribution of steam1 #bbj4 ,periphery of wheel1 #bgg4 ,pet-cock1 #aah1 #adi4 ,petticoat-pipe1 #aac4 ,pile-driving machine1 #bh4 ,pilot1 7see cow-catcher17 #bid1 #cch4 ,piston1 #a2 accident to1 #eji1 #ebb2 diameter of1 #fi1 #afd1 #daf2 construction of1 #agb2 how oiled1 #afi2 inspection of1 #dfg2 momentum of1 #ch1 #bcj1 #bdd2 stroke of1 #daf4 ,piston-head1 #agb4 ,piston-rod1 #b2 action of1 #agd2 breaking of1 #eji2 construction of1 #aga4 ,pitch of screw-threads1 #cda1 #cdc4 ,plan1 xiv4 ,plates1 #eea4 ,potential energy1 #bd1 #bh4 ,pre-admission1 #aig1 #bbj1 #bcg1 #bdj4 ,preface1 iii4 ,pre-release1 #bba1 #bbf1 #bdi4 ,pressure-valve1 #aae4 ,priming1 #agj1 #dhd2 cause and prevention of1 #dhf2 effect of1 #dhh4 ,properties of saturated steam1 table of1 #ehe4 ,proportions of locomotives1 #dab4 ,prosser's expander1 #hd4 ,pump1 #aae2 construction of1 #aae2 failure of1 #eji1 #eah2 freezing of1 #abj1 #ejg1 #ecb2 inspection of1 #dff2 location of1 #aai2 regulation of1 #aai2 working of1 #agf2 in a snow storm1 #ecb4 ,pump-barrel1 #aae4 ,pump-lug1 #agg4 ,pump-plunger1 #aee1 #agg4 ,pump-valve1 #aae4 ,punched holes1 #i1 #ic1 #ajc4 ,punching holes1 #ia1 #ic4 ,pushing-bar1 #cch4 ,pyrometer1 #cig4 ,quadrants1 #bfa4 ,radiation1 #ah1 #aaa2 from boiler1 #cig4 ,rain storm1 running in1 #dig4 ,receiving-tube1 #abj4 ,reciprocating motion1 #e4 ,reflector1 #ccg4 ,release of steam1 #da1 #bba2 governed by1 #bbg2 how affected by link1 #bag4 ,repulsion of particles1 #bh4 ,requirements and duties of locomotive runners1 #edg4 ,reserve engine1 #dig4 ,resistance of trains1 #djf2 on curves1 #daj2 on grades1 #djh2 table of1 #djg1 #eif4 ,responsibility and qualifications of locomotive runners1 #edd4 ,reverse-lever1 #ff1 #ahg2 breaking of1 #ecj2 construction and location of1 #bfa2 length of1 #bfc4 ,reverse-rod1 #ahg1 #bfa2 breaking of1 #ecj4 ,reversing gear1 #bfd4 ,richardson safety valve1 #adj4 ,richard's steam engine indicator1 #bca4 ,riveted seams1 #ia2 strength of1 #ic1 #ie1 #ajf4 ,riveting1 chain1 #ajj2 double1 #ajj2 machine1 #ig2 single1 #ie2 strength of1 #ajc2 strongest form of1 #ii4 ,rivets1 #ij2 arrangement of1 #ia2 crushing of1 #ie1 #ih2 diameter of1 #ih2 proportions of1 #ia2 shearing of1 #id2 staggered1 #aja2 strength of1 #id2 zigzag1 #aja4 ,rocker1 #g2 accident to1 #ebi4 ,rocker-arm1 breaking of1 #ebi2 length of1 #bjd4 ,rocker-pin1 #ahe4 ,rocking grate1 #aeb4 ,rogers ,locomotive ,works1 #djb1 #ega1 #egc4 ,rotary motion1 #e4 ,running-board1 #ccg4 ,running-gear1 #bfh2 inspection of1 #dgc4 ,running locomotives1 #dgh4 ,running off the track1 #eji1 #eab4 ,russia iron1 #aaa4 ,saddles1 #bif4 ,safety chains1 #cdj1 #cej4 ,safety-valve1 #acd2 effect of blowing off1 #dhe2 inspection of1 #dfe2 pressure on1 #acf2 ,richardson's1 #adj4 ,safety-valve lever1 #ace4 ,safety-valve seat1 #aci4 ,sand box1 #cce2 use of1 #dha4 ,saturated steam1 #ac2 properties of1 #ehe4 ,scalds1 treatment of1 #edb4 ,scale1 #dec4 ,screw-threads1 #cda2 form of1 #cdc2 proportions of1 #cde2 system of1 #cdb2 table of1 #cdh4 ,seams1 riveted1 #ia2 strength of1 #ie4 ,section1 xiv4 ,sectional view1 xiv4 ,sectors1 #bfa2 arrangement of notches in1 #bfc4 ,sellers1 ,william1 #cdb2 system of screw-threads1 #cdb1 #cdd4 ,sellers1 ,william ,co41 turn table by1 #def4 ,setting out packing1 #dfi4 ,set-screws1 #agi4 ,shaking grate1 #aeb4 ,shearing1 #id1 #ih4 ,shock1 treatment of1 #eda4 ,shoes1 #big4 ,shunting1 #dbg4 ,side-bearing1 #cef4 ,side elevation1 xiv4 ,side rods1 #agg4 ,side view1 xiv4 ,signals1 #ddg2 observance of1 #dha1 #dhi1 #dic4 ,slack of the train1 #dha4 ,slides1 #agd2 how oiled1 #agf2 wear of1 #age4 ,slide-valve1 #f1 #cj2 advance of1 #ch2 conditions which it must fulfill1 #cj2 disadvantages of first form of1 #cg2 first form of1 #cj2 how made steam tight1 #afi2 inspection of1 #dgb2 lap of1 #dj2 middle position of1 #ahd2 motion of modified by the proportions of link motion1 #bdh2 oiling of1 #afi1 #dib2 proportions of1 #bfj2 setting of1 #bfd2 travel of1 #ch4 ,smith1 ,a4 ,f41 #dda4 ,smith's vacuum brake1 #ddb4 ,smoke1 #cfh2 cause of1 #cgb2 prevention of1 #ejc4 ,smoke-box1 #ff1 #aaa2 temperature in1 #cif4 ,smoke-stack1 #ff2 construction of1 #aab2 inspection of1 #dfe2 proportions of1 #aab2 size of1 #fi4 ,snow1 #dig2 melting of1 #ecb4 ,snow storm1 blockade by1 #ecb2 running in1 #dig4 ,sobriety1 importance of1 #ede4 ,soot1 #cga4 ,spacing rivets1 #if1 #ih4 ,spark deflector1 #aab4 ,speed of locomotives1 #dej4 ,spherical joints1 #afj4 ,spider1 #agb4 ,spread of wheels1 #bhe4 ,spring1 #bie1 #big2 breaking of1 #eji1 #ebe2 construction of1 #big2 curvature of1 #cja1 #cjg2 elasticity of1 #big1 #cjc1 #cjf2 necessity for1 #bie2 number of plates of1 #cjf2 proportions of1 #cjd2 span of1 #cjf2 strength of1 #cjc4 ,spring balance1 #acg4 ,spring balance lever1 #ach4 ,spring hanger1 #big2 attachment of1 #cjh2 breaking of1 #eji4 ,spring strap1 #cjj4 ,staggered rivets1 #aja4 ,starting-valve1 #abf4 ,stations1 running into1 #did2 running past1 #dib2 stop at1 #ejc4 ,stay-bolts1 #gf2 breaking of1 #gi1 #dfc2 strain on1 #gh4 ,steam1 #aj2 absolute pressure of1 #ac1 #ehe2 admission of1 #cj1 #aee2 advantages of using expansively1 #ee2 application of1 #a2 condensation of1 #ag2 cut-off1 #da2 effective pressure of1 #ad2 exhaust of1 #cj2 expansion of1 #ad1 #da1 #dg2 expansive force of1 #a2 generation of greatest amount of1 #ejj2 pressure in cylinders1 #dg1 #eb1 #ec1 #bbc2 pressure1 limit of1 #acd2 pressure of1 #aa2 pressure of after expansion1 #af2 properties of1 #ef1 #ehe2 quantity required1 #dbj2 release of1 #da2 saturated1 #ac2 superheated1 #ac2 total heat of1 #bi1 #eg1 #ehe2 temperature of1 #ehe2 weight of1 #ehe2 volume of1 #ad1 #afc1 #ehe2 wire drawn1 #ei4 ,steam-dome1 #aaj2 location of1 #aaj4 ,steam-chest1 #f2 bursting of1 #eji1 #ebb2 construction of1 #afi2 protection of1 #agj4 ,steam-chest cover1 #afi4 ,steam-gauge1 #adj2 connection of1 #ade2 inspecting of1 #dfe2 testing of1 #ade4 ,steam indicator1 #bca2 method of applying1 #bcd4 ,steam line1 #bcf4 ,steam passage1 #afe4 ,steam pipes1 #aaa1 #aee2 bursting of1 #eji1 #ebb2 construction of1 #aeh4 ,steam ports1 #e2 opening of1 #bag4 ,steam space1 #aji4 ,steam ways1 #e1 #abb2 effect of1 #bbh4 ,steam whistle1 #adf4 ,steel plates1 #dgi4 ,straps1 #agg4 ,stroke1 #af4 ,stub-end1 #agi4 ,studies for mechanics1 locomotive runners1 c41 #edi4 ,stuffing-box1 #agc2 inspection of1 #dgj4 ,suburban railroads1 #dbg2 locomotives for1 #dcf1 #dch4 ,suction-pipe1 #aae4 ,suction-valve1 #aae4 ,sun stroke1 treatment of1 #edc4 ,superheated steam1 #ac4 ,surface-cock1 #dhg4 ,suspending-link1 #bej4 ,suspension1 point of1 #bdi4 ,suspension-links1 #cah4 ,switch1 #bfi4 ,switching locomotive1 #dbg1 #dbh2 running of1 #dii2 engraving of1 #eec4 ,tangent1 #bji4 ,tank1 #fh1 #cdi2 capacity and weight of1 #fi1 #cdf1 #cei2 how strengthened1 #cej4 ,tank locomotive1 #dbh1 #dcb1 #ega1 #egc1 #ege1 #egg1 #egi1 #eha1 #ehc4 ,taunton ,locomotive ,manufacturing ,company1 #dbh4 ,temperature in fire-box1 #chg2 necessary to ignite coal gas1 #chg4 ,tender1 #fh2 capacity and weight of1 #fi1 #cdi1 #ceg2 construction of1 #cdi4 ,tender trucks1 #cej1 #cef4 ,tender-valve1 #cej4 ,tensile strain1 #hi4 ,ten-wheeled locomotive1 #dcj1 #efe4 ,testing of boilers1 #dfa2 of steam gauges1 #ade4 ,threads 7of screws72 see screw-threads1 #cda4 ,three-legged principle1 #cag4 ,throttle-pipe1 #aaa4 ,throttle-valve1 #aee2 failure of1 #eaj1 #ecj2 inspection of1 #dff2 operation of1 #aeh2 use of1 #dha4 ,throttle-valve lever1 #aeh4 ,throw of eccentric1 #ca4 ,thumb tool1 #hd4 ,tires1 #fc1 #bhe2 breaking of1 #eji1 #ebd2 how fastened1 #bhf2 standard size of1 #bhh4 ,tools for engine1 #dgf4 ,top view1 xiv4 ,total heat of combustion1 #chj1 #cic2 of steam1 #bi1 #eg4 ,total pressure of steam1 table of1 #ehe4 ,tourniquet1 #ecg4 ,t pipe1 #aei4 ,traction1 #cai4 ,tractive power1 #cba4 ,traffic1 freight and passenger1 #dbg4 ,trailing wheels1 #fe2 breaking of1 #ebd4 ,train1 protection of1 #ead4 ,transverse section1 xv4 ,travel of valve1 #ch2 effect of changing1 #db1 #aie1 #bad1 #baf2 how changed1 #ahg4 ,tread of wheel1 #bgg4 ,truck1 #bfh2 construction of1 #cad2 effect of on movement of locomotive around curves1 #bgc2 for tender1 #cef2 lateral motion of1 #cag2 resistance to rolling1 #bhj2 use of1 #bfi2 with single pair of wheels1 #bga1 #dcj4 ,truck axle1 #bhj2 breaking of1 #ebd4 ,truck boxes1 #bib1 #cad4 ,truck frame1 #cad4 ,truck springs1 #cad4 ,truck wheels1 #fe1 #bfh2 breaking of1 #ebd2 construction of1 #bia2 size of1 #fh2 slip of1 #bgc2 weight on1 #fi2 why two are used1 #bfi4 ,truss-bars1 #caf4 ,try-cocks1 #acj4 ,tubes1 #ff2 arrangement of1 #ha2 bursting or collapse of1 #eji1 #eaf2 fastening of1 #hc2 number and size of1 #fi1 #gd4 ,tube-expander1 #hd4 ,turn-table1 #dea2 construction of1 #dee4 ,unguent1 #cfj4 ,ultimate strength1 #ij2 of springs1 #cjb4 ,unit of heat1 #eh4 ,unit of work1 #bc4 ,united ,states standard for screw-threads1 #cdc4 ,vacuum brake1 #ddb2 construction of1 #ddf4 ,vacuum line1 #dh4 ,valve1 slide1 #f4 7,see slide-valve74 ,valve1 ,allen's1 #bbd4 ,valve-face1 #dj4 ,valve-gear1 #aha2 construction of1 #aha2 dimensions of1 #baf2 injury to1 #eaj2 inspection of1 #dgb2 model of1 #bej4 ,valve-rod1 #g4 ,valve-seat1 #e4 ,valve-stem1 #g2 accident to1 #ebi4 ,vapor1 #aj4 ,variable exhaust1 #afc4 ,venous bleeding1 #ecf4 ,vertical section1 xiv4 ,volume1 #ad4 ,wagon top1 #aji4 ,waist of boiler1 #fg4 ,ward's air brake1 #ddb4 ,water1 amount evaporated per pound of coal1 #gc1 #cid2 freezing of1 #ejg2 height of in boiler1 #acj1 #dhd2 muddy1 #dhf2 8solid10 #dhg2 supply exhausted1 #eca4 ,water crane1 #deb4 ,water gauge1 #acj1 #acb4 ,water grate1 #aeb4 ,water space1 #fg2 size of1 #fi1 #ge4 ,water supply1 #dec4 ,water table1 #cii4 ,water tank1 effect of carrying weight of on driving-wheels1 #dcc1 #dea4 ,wedges1 #bid1 #big2 bolts for1 #dge4 ,weight1 distribution of1 #dac4 ,welt1 #ajj1 #ajc4 ,westinghouse brake1 #ddb4 ,wheels1 driving1 #bfh2 adhesion of1 #fb2 breaking of1 #eji1 #ebd2 carrying1 #bfh2 size of1 #fh2 trailing1 #fe2 truck1 #fe1 #bfh4 ,wheel-base1 #fi1 #bhe4 ,wheel centres1 #fc1 #bhf4 ,wheel guards1 #cdj4 ,wild engine1 #dih4 ,wire drawn1 #ei1 #aig1 #dhb4 ,wire netting1 #dfe2 method of cleaning1 #dff4 ,work1 #bb2 convertible into heat1 #be4 ,working water1 #agj4 ,wrist-pin1 #age4 ,wyman1 ,d4 ,w41 locomotive by1 #ehc4 ,y1 #dfj4 ,zigzag rivets1 #aja4 ,transcriber's ,notes ,inconsistencies in spelling1 lay-out1 hyphenation1 etc4 have been retained1 except as mentioned under ,changes below4 ,some reference letters' case in the text does not correspond to that shown in the illustration1 and some of the reference letters are used inconsistently in different illustrations2 this has not been rectified unless mentioned below4 ,the not always numerical order of the illustrations in this e-text is the order of the source document4 ,depending on the hard- and software used to read this text and their settings1 not all elements may display as intended4 ,the scale as indicated in the illustrations in this e-text is not necessarily correct4 ,several characters as used in this text are used to represent the shape of the symbol or letter rather than the symbol's 7e4g41 7 or letter's 7e4g41 ,u7 actual meaning4 ,page #dg1 444 a spiral spring1 s s1 fig4 #ca1 which is compressed 4443 the letters s are not visible in the illustration 7the spring is74 ,page #eb1 444 if we construct a scale ,s1 ,s1 fig4 #ch1 4443 the printing quality of the source document was not sufficient to make this entirely visible in the illustration2 the text and fig4 #ci may provide clarity4 ,the parts that were legible have been enhanced4 ,page #gg3 ,fig4 #da contains different reference letters h3 two in the smoke stack 7left-hand side of the illustration71 one underneath the steam whistle4 ,both are referenced in the text4 ,page #ajb1 444 the distance d f will then be the centre 4443 one or more words may be missing 7444 which will then be 444 or similar74 ,page #aed1 444 with two handles1 l1 l1 fig4 #ga1 which are raised 4443 reference letters l do not occur in the illustration 7nor are they listed in the parts list following the illustration74 ,page #aff1 ,fig4 #ic3 the right-most reference letter is an upside-down ,w1 not an ,m4 ,page #aha1 444 and the other two the reverse way3 possibly an error for 444 and the other the reverse way4 ,page #beh1 caption with fig4 #ade3 ,scale in4 #a foot is probably an error for ,scale in4 #a inch4 ,page #bfi1 444 and y1 plate ,,ii1 and fig4 #dj1 the centre-pin 4443 the centre-pin is indicated by ,y in ,plate ,,ii4 ,page #ccg1 ,the running-boards are planks1 i i1 plate ,i1 4443 the reference letters i i are not visible in ,plate ,i4 ,page #dcj1 ,sentence starting ,for this reason a truck consisting of a single pair of wheels1 4443 as printed in the source document2 some text may be missing4 ,page #ddh_/ddi1 ,table and paragraph starting ,from this table it will be seen 4443 probably the last two columns of the table list decimal fractions rather than percentages 7e4g41 fuel is probably #j4c of operating costs of locomotives rather than #j4c74 ,page #edd3 ,part ,,xl should have been called ,part ,,xxx4 ,appendices3 unless mentioned under ,changes below the tables are given here as printed1 although they may contain 7minor7 errors4 ,changes made ,footnotes and illustrations have been moved out of text paragraphs4 ,some of the illustrations have been rotated4 ,figure numbers and scale indicators have been removed from within some illustrations and have been transcribed as 7top or bottom7 captions4 ,where they were missing1 periods have been added to illustration captions4 ,numbered questions have 7where relevant7 been standardised to end in a question mark4 ,reference letters in the text have been standardised to italics4 ,some obviously missing punctuation has been inserted2 some minor obvious typographical errors were corrected silently4 ,in some tables and lists ditto marks have been replaced with the dittoed text4 ,page iv3 ,die ,schule des ,locomotivfuhrers 444 changed to ,die ,schule des ,locomotivfhrers 4444 ,page xvi3 444 as shown in the sections of the apple at ,a and ,b4 changed to 444 as shown in the sections of the apple at ,c and ,d4 ,page #a3 ,the steam1 if admitted at c 444 changed to ,the steam1 if admitted at ,c 4444 ,page #dj3 444 those portions of the face h1 i1 and p1 q1 which cover the steam-ports1 444 changed to 444 those portions of the face h1 i1 and h1 q1 which cover the steam-ports 4444 ,page #ef3 444 conditions which were used in the answer to ,question #fj 444 changed to 444 conditions which were used in the answer to ,question #eg 4444 ,page #eh3 ,it was shown in answer to ,question #ef 444 changed to ,it was shown in answer to ,question #eg 4444 ,page #ajb3 444 we will step off the distance d f f 444 changed to 444 we will step off the distance d f 4444 ,page #aaa3 444 7shown also in fig4 #dc17 444 changed to 444 7shown also in fig4 #dj17 4444 ,page #abi3 first comma deleted from a1 a1 ,heater ,pipe4 ,page #ace3 ,fig4 #gd3 reference letter ,j changed to j4 ,page #afb3 444 flanges1 f f1 cast on the pipes4 changed to flanges1 f1 f1 cast on the pipes4 ,page #afe3 444 heads1 ,a and ,b1 444 changed to 444 heads1 ,a and ,b1 4444 ,page #agf3 444 the tops guides are usually 444 changed to 444 the top guides are usually 4444 ,page #agi3 444 the journals of the coupling-rods1 the brasses at m1 m1 444 changed to 444 the journals of the coupling-rods1 the brasses at n1 n1 4444 ,page #aie3 ,thus the line -o -o1 444 changed to ,thus the line -#j -#j 4444 ,page #baf1 table1 row #d1 column ,point of release1 ,backward stroke #bj changed to #bj4 ,page #bbj3 444 the slide-valve and ink motion8 changed to 444 the slide-valve and link motion8 ,page #bcd and #bcf3 ,the first illustration with caption ,fig4 #acf has been renumbered ,fig4 #acf;a1 the second one ,fig4 #acf;b4 ,page #bcf1 ,fig4 #acf;b3 reference letter e 7top centre7 changed to c4 ,page #bfa3 ,the reverse-rod l k1 which connects the lever with the vertical arm k 444 changed to ,the reverse-rod e k1 which connects the lever with the vertical arm k 4444 ,page #bha3 444 if two pairs of wheels1 a1 a1 b1 b1 fig4 #aea1 444 changed to 444 if two pairs of wheels1 a a1 b b1 fig4 #aea1 4444 ,page #bib3 444 a heavy timber1 called a bumper-timber1 ,e ,e1 plates ,i1 ,,ii and ,,iii1 444 changed to 444 a heavy timber1 called a bumper-timber1 ,e ,e1 plates ,i1 ,,ii and ,,iii1 4444 ,page #big3 ,these plates are of different lengths1 as shown at ,b1 ,b1 in fig4 #afi1 444 changed to ,these plates are of different lengths1 as shown at ,b1 ,b1 in fig4 #afi1 4444 ,page #cjh1 answer to question #bii3 references to ,fig4 #agh changed to ,fig4 #agg 7three times74 ,page #cbg3 444 the end of a longer lever ,e ,g ,b1 fig4 #aib1 444 changed to 444 the end of a longer lever ,e ,g ,b1 fig4 #aib1 4444 ,page #ccg3 ,the hand-rails1 m m m1 are brass or iron pipes 444 changed to ,the hand-rails1 m m m1 are brass or iron pipes 4444 ,page #cde3 closing quote mark inserted after formula4 ,page #cdf1 first formula3 #a1bff changed to #a4bff as elsewhere4 ,page #cff3 the source has two footnote anchors for a single footnote2 the footnote has been copied4 ,page #dbc3 444 #fdi1gbe units of heats1 444 changed to 444 #fdi1gbe units of heat1 4444 ,page #dcb1 answer to question #dce3 quote marks inserted around ,consolidation as elsewhere4 ,page #dii1 footnote #aaa3 ,katechismus der ,einrichtung und ,betriebes der ,locomtive changed to ,katechismus der ,einrichtung und des ,betriebes der ,locomotive4 ,page #edd1 footnote#aai3 ,katechismus der ,einrichtung und ,betriebes der ,locomotive changed to ,katechismus der ,einrichtung und des ,betriebes der ,locomotive4 ,page #efa1 ,plate ,,viii3 ,scale1 in4 ft4 changed to ,scale1 in4 #a ft4 ,appendices3 chapter headings ,appendix ,i1 ,appendix ,,ii1 ,appendix ,,iii and ,appendix ,,iv have been inserted4 ,index3 some page numbers were corrected4 ,minor spelling differences between the text and the index have not been changed4