IMAGE EVALUATION TEST TARGET (MT-3) /y :^ 4^ '"', s- 'V'" 1.0 I.I 11.25 £ Itf |2C — 6" 0^A Hiotographic Sdences Corporation 23 WIST MAIN STRtr WEBSTill,N.Y. MStO (716)072-4903 ^\ V ^. r JirNK 911, IHIM. Fig. I. -Outside. Fig. 2.-lntide. The Thompson Improved Indicator was patented by J. W. Thompson, Aug. 31, 1875 and July I3, 1881 ; and by careful con- sideration of the demands of the engineering public, we have from time to time improved it, and it is now conceded by all prominent engineers to be the standard steam-engine indicator for the U.S. and all foreign countries. The radical improvements, as made in the old-style Thompson Indicator, consists of lightening the moving parts, substituting steel screws in ph.ce of taper pins, using a very light steel link instead of a large brass one, reducing the weight of the pencil lever, also weight of squares on trunk of piston, and lock-nut on end of spin- dle, and increasing the bearing on connection of parellel motion. By shortening the length, and reducing the actual weight of the paper cylinder just one half, and by shortening the bearing on spindle, also lowering the spring casing to a nearer plane to that in which the cord runs, we have reduced the momentum of the paper cylinder to a very small amount. All of these improvements have lessened the amount of friction, which was heretofore very small, but is now reduced to a minimum ; and, furthermore, they fim^noat) 8tea/n Qbuq^ ^o.. BostOQ. tend to iinprovi', on the whule, nn instrument wIiumc principle has ulways heen of undoubted correctneKH. In callin); attention to the fentures of this instrument, we prefer to do 8o Hubject to all amenities of husineHs courtesy, leaving; our pnxhictH to speak for themselves, an.priii<^. >,. The weight of the drum. » It is evident that but two of these factors can be secured in the construction of the iiistrumeiU ; namely, the i'ourth and fifth : and these beiuy; once adapted to a y;i\en speed, the instrument cannot be adapted to any other speed, except to the very limited extent allowed by \ariations of the tensit)n of the spring or in the length of the diagram. 'I'he difVcrence re(|iiircd for ditVerent speeds would, other things e(|ual be (litlerent lenj^ths of spring; the slower s^m jds recpiiring the longer springs in inxerse proportion to the number of revolutions per minute. Tims, an instnunent being properly adjusted for a speed of ^(K) revolutions, would retpiire a spring twenty-five times longer for a speed of 6(j. that being the square of the ratio of the two speeds, 5 to i . Also, if applied to the latter speed as adapted to the higher speed, the stress on the cord would vary nearly as nnich as the force of the spring ; and the resulting y u link f this link remain so will affect jual to it, mentwill lot in any ^hen the ting-rod, attaching motion) Its, play possible :imes the ovement ction it received y lever- plan of 1 sprmg lirterent f\in^r'iQaT) Stearn Cjau^^ ^o., BoetOQ. ^ speeds of engines. As little or as much of the spring can be taken up or let out as desired, thereby providing for fine adjustments, and not, as in other instruments, where a whole coil must be taken up, or noiie. For high speeds, our instrument will give accurate results for all practical purposes, without any special adjustments further than to give sufficient tension to keep the cord taut at all points. When exceptionally accurate work is desired, the length of the diagram may be carefully measured, and compared with the length of a line traced on the paper when the engine is moved slowly. If the diagram is found to differ in length from this line, vary the tension of the spring till they agree. The paper cylinder, or *' drum," we now make with covered top. Lidding Pulley for Paper Cylinder-. This latest improvement in the Thompson Improved Indicator was patented June 26, 1883, and consists (see Fig. i) of a wheel which leads the cord through the hole, in contact with the scored wheel, over which the cord can be run to any possible angle, to connect with the motion, wherever it may be, or of whatever kind. The pulley works in a sleeve which rotates in the st Kid accord- ing to the adjustments required, and which is held in its position, where adjusted by the thumb screw, which acts as a binding-screw working in the groove on the sleeve. By this it is held in any position that may be chosen, and yet be free to revolve the moment the binding-screw is loosened, without any possibility of interfering with the motion by means of scarring the sleeve, or disturbing the particles of metal on surface. It also gives all the desired freedom of motion and facility of adjustment. By means of the set screw, the stand which carries the wheel can be adjusted to run the cord to any possible angle within a range of three hundred and sixty degrees. In the double pulley arrangement, as used in other indicators, the range of adjustment is limited; and in some cases the cord cannot be made to run in a number of certain directions without iia\ ing it run grating, rough and uneven. In this improved swivel pulley, the use of carrying-pulleys is done away with, and from the fact, that, no matter what the angle *1^ f\f[\er\Qa[) S^(^an\ (jau^^ ^o., Bostop. of deflection may be, or what direction it may be necessary to take the cord, it will work smoothly ; for the pulley face and the face of the groove on the paper cylinder are always in the proper position, one with the other, to take the cord to the motion, wherever that may be arranged. ' • ' - • .-■ V In high-speed short-stroke electric-light engines, great range of adjustment is very important ; for considerable trouble is experienced sometimes, upon engines running three hundred and fifty and three hundred and sixty revolutions per minute, in so arranging the cords, as to use independent arcs, or making such connections with refer- ence to right lines that no distortion of diagram should be given. We are the sole owners of the swivel pulley, having purchased the United States patent from the patentee ; and we hereby caution all parties against purchasing any other indicator having this device, as we shall hold them responsible, as well as the manufacturer. Stop Motion. It is provided with a " stop motion" (see Fig, 3) which is so arranged that the horn-handle screw can be screwed up against the post or stojD placed midway be- tween paper cylinder and steam cylinder so as to regulate the pressure of pencil lead upon the paper. Springs, The best and finest quality of steel wire is used in making our springs ; and they are all wound on a mandrel, and tempered in the most careful manner by the oldest and most experienced workmen in the business. All our springs are wound on mandrels from four to four and one-half threads to the inch, and thereby give more wire to each spring, and a consequent less strain, than if wound, as in springs of other indicators, on mandrels two to three threads to the inch. Fig. 3. »ry to take the face of r position, ;rever that t range of perienced and three the cords, ■ith refer- given. )urchased y caution is device, urer. lich is so ainst the Iway be- ul steam late the d upon lality of ing our wound ered in by the ienced undon ur and inch, kire to 'quent on jm fim^r'Kaj) Steam Qau^^ Qo., BostoQ. Whatever grinding is done to lighten a spring, amounts to very Vj..ie ; in fact, at the most, it is never ground to cause more than one to three pounds difterence in one hundred pounds ; and, when the sensitiveness of our springs is considered, very little grinding will produce this result. All springs used in other instruments, whether double, single, or having a steel bead for bottom end, when connected, and under steam pressure, do not possess the freedom of movement claimed, but are, in fact, as rigid as those made with double heads, like ours. All springs we make are scaled, providing for vacuum ; and the capacity of any spring can be ascertained by the following general rule: Multiply scale of spring by 2^, and subtract 15, and the result will be the limit of pounds steam pressure to which spring should be subjected. Example: 40-pound spring x 2^ = 100— 15 = 85 pounds pressure, capacity of a 40-pound spring. To adapt the Thompson Improved Indicator to all pressures, we make springs to any desired scale. The following are the most generally used : 8, 10, 1 2, 16, 20, 2^, 30, 32, 40, 48, 50, 56, 60, 64, 80, 100. For pressures from 6^ to 85 pounds, a 40-pound spring is best adapted ; for, as 40 pounds pressure on a 40-pound spring will raise pencil one inch, 80 pounds pressure on the same spring will raise pencil about two inches, which is the usual height of a diagram. VacuutH Springs. All our springs are scaled providing for vacuum, but close ex- periments have shov/n us that from the fact that springs compress and elongate in unlike proportions, the regular pressure springs vary about one pound in fifteen, or about 6^ per cent. We make a special vacuum sjiring, regular thread, scaled for vacuum onl}', which we furnish at the regular price for pressure spring, $5.00 each. All of our springs are subjected to a severe test before leaving the factory, and they will always be found accurate in actual use. To Change Springs, First, unscrew the milled nut at the top of steam cylinder; then take out piston, with arm and connections; disconnect pencil lever and piston by unscrewing the small knurled-headed screw which connects them ; remove the spring from the piston, substitute desired one, and put together in same manner, being careful, of course, to : I pm^ri^aQ St^am Qau^e Qo., 605(017. ^P screw the spring up against shoulder, and down full to the piston head. This arrangement for changing springs is simple, easy, and conven- ient, and does not require the use of any wrench or pin of any kind. To change springs in all other instruments, either a pin or a wrench must be inserted between the coils of the spring, discon- necting the piston. By reason of the form of the coils, not overy^j^ of an inch throw can be got by the pin or wrench at onetime. When the piston is hot, the trouble attending such an operation can be imagined. Furthermore, in the Thompson Improved Indicator, the ball and socket joint is adjusted to scale with each spring a com- plete vacuum, or its equivalent, 14.7 pounds; and this adjustment need never be changed : but in other instruments, every time a spring is changed, this adjustment must necessarily be changed ; and the re-adjustment, to show a vacuum with each spring, rests with the party using indicator. Right and Left Hand Indicators, Fig. 4.— Right Hand. Fig. 5.-Left Hand. To facilitate the adjustment of the Thompson Improved Indi- cator to all styles and makes of en<,Mnes, we make the Indicator right or left hand, as desired. In a right-hand indicator, the peaicil lever and connections, in % ID ^ piston head, and conven- of any kind. a pin or a ing, discon- otoverj'j^of ne. When tion can be Indicator, >ring a corn- adjustment ery time a changed ; pring, rests )vcd Indi- Indicator crions, in pmerieai) Steam Qau^e ^o., Bostop. m swinging away frotti the paper cylinder, swing to the right,, and vice versa in a left-hana indicator. By manipulating the cord-carrying arrangement, a right-hand indicator can be used right or lefl hand as desired ; and the same is true of the lefl hapd being used right hand. Note. — In a left-hand instrument, the thumb screw for tight- ening or loosening the drum spring has /^/-hand thread ; therefore when desirous of tightening or loosening the drum spring, start the thumb screw by turning to the right, or just opposite to a right- hand screw. Detent Motion, The Detent Motion, as applied to the Thompson Indicator, consists of a pawl mounted on a stud, in combination with a spring and ratchet, by the use of which the paper cylinder can be stopped and a change of cards made without un-hooking or disconnecting the Indicator cord. By moving the pawl so as to catch in the teeth of the ratchet on base of paper cylinder, (see Fig. 6) the latter is held stationary as the engine completes its stroke. The cord, being en- tirely free, runs loosely with the motion of the engine, but the paper cylinder being stationary, the cards can be changed with- out the least disturbance of ad- justments. By throwing the pawl out of the ratchet the paper cylinder is released, and inmiediately resumes its stroke with the engine, but care must be taken not to allow the paper cylinder, by force of its spring, '^'fl- "• to return to the stop with a thump ; this can easily be done by simply holding the cord slightly witli the thumb and hnger until the beginning of the next stroke. This device obviates the change of adjustments, and is particu- larly valuable to amateurs and others not familiar with the use of the II i: 1 ill •W? fimemaq 8t^am Oau^e ^o., Bostop. Indicator. It is also valuable to users ot' the Indicator on very quick running electric lijjht engines, and in all cases where the circum- stances are such that the disconnection of the connecting cord must cause the operator considerable trouble, and the loss of valuable time. Indicators are not ecjuipped with Detent Motion unless so order- ed, and when so equipped, a slight extra charge is made. PRICK EXTRA FOR WETENT MOTION, •3.00 Adaptability of the Thomptton Improvetf IniHcator for Extreme High PresHuren, C a. Thompson Improved Indicator. >i' and '4 inch area pistons. All Thompson Improved Indicators are provided with a piston .798 inch diaineter== J iiich area, which, with the 100-pound spring, provides for indicating pressure up to 350 pounds. ¥ /tm^rieai) Steam Oau^^ Qo., BostOQ. ^p When pressure above that is to be indicated, we furnish an ex- tra piston .564 inch chanieter^J-inch area, vvliich, when substituted for the ^-inch area piston, doul)les the capacity of each spring, there- by adapting the indicator for indicating pressures up to 500 pounds. From the above, it will be seen, that when an indicator is fur- nished with the regular ^-inch area piston, and nn extra ^-inch area piston in addition, the instrument can be used to indicate all press- ures from o to 500 pounds. PRICE OF EXTRA 1-4 INCU AREA PISTON •10.00 Summing up the features of the Thompson Improved Indicator, it will be seen that it has advantages over all others in the following points : — It is handsome in design, — mechanically and theoretically as near perfection as it is possible to obtain, — convenient, and simple in arrangement. All its moving parts are very light ; and it is made of materials carefully selected and admirably fitted, thereby insuring durability. It is adapted for all pressures and speeds practicable, it is adapted for application to all situations, and its simplicity and accuracy recommend it to those least experienced in the use of an indicator. General Use and Care of the Thompson Improved Indicator, Before using indicator, take it apart, clean and oil it. Try each part separately. See if it works smoothly : if so, put it together without the spring. Lift the pencil lever, and let it fall : if perfectly free, put in the spring, and connect. Give it steam, but do not at- tempt to take a card until it blows dry steam through the relief. If the oil from the engine gums the indicator, always take it otY and clean it. Never use lead in connecting : it is not necessary, and is liable to get into the instrument. Attach indicator direct to the cock. The lighter the spring used, the higher will be the diagram pro- duced, and, in consequence, the more accurate measurements can be obtained ; therefore, in selecting a spring, select one to give dia- gram about two inches high. 13 ill ' '' 1 in pf[\er\Qai) Stea/n Qau^e ^o., Bostoi). In selecting a suitable spring for a given pressure, always bear in mind the following general rulf, as giving the maximum press- ure to which each spring should be sul)jecteS •^- /tmerioaQ 3^^^^ (i^^9? ^o.. Boetoi^. • '^t- It is apparent that the adjustability of the guiding-pulley will give a smooth and regular rotation to the |)a|itr cylinder, no matter from what direction the mo- tion may be imparted. The improvement is in keeping with the rest of the details of the instrument, and is an invaluable adjimc t where the indicator motion is not a )>ermaticnt fixture. It has no special ailvantage, however, for use on naval ves- sels, as the indicator motion is permanent and direct ; but it will greatly facilitate the taking of cards from the air and circulating pumps. 2d, There is a modification of the pencil-carrying levers, whereby they are lightened, stiffened, and harmonized. Their principle and action, however, remain unchanged. The working-lever is now a light steel rod forked at either end, jointed at the lower end to the body of the movable arm, and to the main lever at the upper end. The length of bearing is jj of an inch for the lower, and jjif for the upper. The old style is a latticed plate, forked at either end, having ccji'il lengths of bearing of li^J of an inch. The main of pencil lever and radius link are of "drop "forged steel, the main lever being bossed on either side, to give greater stability of bearing at the piston and radius-bar connections, the width of bearing being .12 of an inch. The bearing-pins for socket bar and piston connection are of steel, and thread- ed at the end; those for the radius bar are straight steel pins. The levers, forked end of piston rod, and trunk connections, have been much reduced in weight ; and, although reduced to a minimum of lightness, the superior connections will give much greater durability. The instrument without the improvements has a quaint, ungainly, and ancient look in comparison with the newer design. The weights of the trunk, piston rod, and levers of parallel motion are, 31 grammes old design, and 15 grammes new design. Hence the latter is 31 — 15 x 100 = 51.6 per cent, lighter than the former. 3« There being no reduction in the pistons, and being of equal weight, their weight is not included in the above. 3d, This improvement consists in the ratcheting of the base rim of the paper- cylinder carrier a short distance on its circumference at the limit of its rotation ; this, in combination with a spring pawl, holds the cylinder when desired, and en- ables the user to take off the card and renew, without unhooking the cord. This will save trouble and much annoyance, which will be fully appreciated by every user of the instrument. 4th, This is a device to regulate the pressure of the pencil on the paper when tracing a diagram, and consists of a steel wire post riveted to the base plate of the paper cylinder, and a delicate handle of suitable length tapped through the movable arm, by which means a light line may be always assured ; for with the pencil lightly placed on the paper, and the handle adjusted against the post, the heaviest hand must take as fine a card as a hand with the most delicate touch. This will be duly appreciated by those who have to use it in naval vessels, as the pencil can be ad- justed before taking the instrument to the generally dim-lighted and hot place it is used in. The instrument has been lightened by lowering the spring drum, thus shorten- ing the spindle ; also by reducing the length and thickness of material of the cylin- der. A cap is brazed on the cylinder, having a central orifice, through which the spindle of spring drum passes for strengthening and steadying the cylinder. . It has been lightened in evexy part that would admit of it. 16 ^fi give a smooth ction the nio- ot the detailH niotioii in Dot on naval vcs- :atly facilitate ehy they are wever, remain jointed at the le upper end. uiiper. The of bearing of irop " forfied ity of bearing 2 of an inch. , and thread- evers, forked weight; and, ins will give and ancient ^tion are, 31 ' 3' — '5 X 100 3> their weight the paper- rotation ; :d, and en- ord. This by every aper when late of the e movable ncil lightly est hand ill be duly :an be ad- place it is shorten- the cylin- t'hich the ^ w m f\n\(^r\Qar) 8tean d^a^R ^o., Bo8t09. Tents were made with several (llfferrnt fla««f« of cn«ine«, runging In »pecd from so *" '5° icvoliitionH, — no higlu-r upecd could lie found,— the »te«m-|»r«'H<»nre varvinn in pressure from (o to lyo |x>undH. I li«- tcstH were more than Hatisfactory, the improvements proving to be real and >t'n»i1ile. The material used is of the (inest (piality, and the workmanship of a high order. All the workmen, havinn liecn iiig.igcrl many years in instrument making, arc reli- able and >kiifiil in all tliu details. The sprin^js are tested by |)l.»( ing tlicm in a mathiitc wliit h alternately compresses and extends thcin 1,500 times in a n\iniite ; this "jigging" process being done for the purjicse of insnring the springs against any subsetjuenl set, orch.mge in the molecules of the nietal when in use. The cylinder and piston are fitted to a standard gauge, anil are therefore inter- changeable, as are all parts of the instrument. The whole is nickel -plated. The cost of the iiistiunieif complete is eighty-five dollars. The senior member of the present board was senior member of a l)Oard to test the Thompson Indicator in 1S79. The boaril reported favorably, and rccomtnend- ed its use in the United States Navy, since which time it has been in general use in naval vessels, and is therefore well known The imprcvements have added j;reatly to Its accuracy, delicacy, sensitiveness, and durability; making the instrument about, if not wholly, as near perfection as can be obtained: and we have no hesitancy whatever in recommending its use in the naval service. Very respectfully your obedient servants, (.Signed) F. A. WILSON, JAMKS HUTTERWORTH, CV//7 /tmeri^ar) Steam (jau^e ^o., BostoQ. '^ Ttelirving that itiiii Initriimcnt in a reliable ami »en»Uive one, we reiipectfully rccottinieiid iln ailoptinn in the iiav.il tcrviic (Signet!) !• A W 1 1. SON, Chit/ Enninttr, I'.S.X. (;. M. 1,. MAtCAU IV, /'..•» JHj:iHffr, U.SuV. NV M 11 1 1 A l< K I S, /'.A. Inamttr, V.S.N, Tn CoMMonoRK (;KMRf;F. M. Kansom, U. S. N., l't>mm>i>iii \\\y J^K>.^v^ iiv liMritit' l.i.i . imvp^nx, N<». jiH Hay SiKKf r, Jm-iKY « MY, N. j , ►«!». ^ iJWy II. K. MnoHK, \,^!»<>n Impnutfl Indicjlor vcn* recently fur> iii»lu(l mc. I lie 111 w form of paper tlrndi t-n^l'lc* mt- lo tati- •Jntx'nimj uf' !•' tit kmuittj moliilioHM per iiu'muc, wilhimt alfccling ii) Any senile thrir accuracy. I he imprnvrd p.ir.tllcl iiioiiui) i., ,\\\ tli.it coiilil 'h- (jesirtil. At HUr time i had eight in (li( aiors of (lilfcmit m.iiiiifai luri', i///./ h^i^nd I'v >t» I aHioii>» where prci i'(i.r/iW, iJ/».*i. (iiiits, — \"()ur favor of thi- ^ist of January, rc<(iicsli ; a statement of tiie facts concerning the exchange of our ( ro.sl)y Indicators for \ le Ihompson Improved at our mills, is received and noted. Replying, will say that some time ago we purchased, in good faith, a pair of Crosby Indicators, of the kind known as N'o. 2. These instruments, from the first, were a source of trouble to us. The diagrams woukl show a loss, from boiler pressure, of seven to nine \< uiuis, which no ad|ii»t- incnt of the valve of our engine would remedy. The ari.-igemcnt for changing springs in the Crosby instruments is complicated, and tci 'Us to perform. The adjustment re(|uiied in maintaining a |>ropcr height of pi ;k il, especially for con- densing-engines, like oursj is so fine ami so easily disarranged, that we think, every thing considered, the instrument unfit for ordinary everyday i.se. With these facts in mind, we wrote you, reipicsting a jiair of Thompson Improved Indicators for trial, with your best terms for the e.xchanKC. We have had the I'liompstin Indicators three or four weeks ami are more than |ileased with them. The diagrams with these instruments show a difference of 01 Iv oiif pound from boiler pressure, and a very fine distribution of steam, and thiswii c>ut any alteration in the valves of our engines. The arrangement in these instrmrients for changing springs is simple, readily understood, and cpiickly performed ; and the height of pencil, once adjusted, is always the same. The swivel jnilley for guiding the cord deserves special conimendation, and we unhesitatingly pronounce the Thompson Improveil Indicator to be the best indicator for our use we have \ •-•t seen; and we enclose check to balance our account. I'iease acknowledge the same, and oblige Vours respectfully, W.M. .S. I'OTTKR, Treasurer. % 19 3 pm^rieap Steam Cjaii^^ ^o., BostOQ. ^ ni! Boston, June r, 1884. American Steam Gauce Company, ^w/Rr., Sn/\ri/ite//(le/it. J >e6 Churdon Street, J^os/on, Miiss. (Jentlenien, — We have had several of the Thompson Indicators in constant use ever since their first introduction, applying them to engines of all sizes and speeds, and working under all pressures and grades of expansion usuallv met with in engineering practice, and have never met with a single instance in which the amount of vibration was sutiicieiit to impair the value of the diagram |)roduced. Previous to its introduction, it was not an uncommon thing in our experience, in indicating ^1: mi I ?• ^ ir and report to ;ther the valves om as a part of or engines of a the economical )al themselves, g two hundred istinct lines, as ible to tell the Superintendent. e most precise motive engines ins per minute y to a hundred tint:; lini^'ineer. iss. in constant h have been As our prac- ested ; as for cut-off at one son Indicator unient within cnuRcir. K t'OMPANV, SSo. i'S. constant use and speeds, net with in the amount i. I'revious 1 indicating f\n\qr\^aq Steam Qau^(^ Qo., Bo5t09. engines running at high m moderately high rotative speed, and woiking expansively under good pressure, to encounter such excessive vibration as to render the results worthless; and, independently of the (picstion of vibration, we have found that its other merits (which will I)e a|>parent to engineers of any degree of familiarity with indicators) are such as to give it a decided superiority under all circumstances. The marvellous delicacy and perfection of its action cannot be better illustrated than by the accompanying cut, which represents a friction card taken by ourselves from one of our 16 by 32 inch cut-off condensing engines. It represents conditions under which distortion from vibration would naturally be very excessive with the most imjjroved instrument. The card is one of a number taken while adjusting the condenser, and stopping air leaks. Speed of engine, ninety revolutions per minute; scale, forty pounds- Five-inch throttle open. Very truly, etc., HUCKLVE KNGINE COMPANY, I'ER Ji)i;i. Sharp, President. Oi-'i'KE OF Frank H. I'ond, i\\ North F.ichth Sikkf.t, ."^ \. I.oi'is, Feb. 3, I SSo. American Steam Gait.e (.'omi' any, j'i') ( '//,/r./ri// ^a, HoUou. Mass. diUtUiitiii, — \'our faviii of the Jijtii is at hand. In re])lv. would sav rei;ardin^; the Thompson Iiuiicator, having used botli that and tlie kiiliai(l>. I ( unsidcr it far supeiior in sensitiveness and tMse of motion, and well adapted to be useii on the ilMiek-uinning engines of the present day. There have been many improvements embodied in tiie Thompson whi( h e,\|)erience has shown to be necessary, and it seems to meet all jiractieal recjuirements. \ours trulv, FKA.NK H. I'OM). ti 23 #t; hi' I ii 1 !:-!nl W^ fi(i\er\QaT) St^am Cau^^ Qo., BostOQ. "^ St. Louis Gas-Light Company, No. 511 Olive Street. St. Loris, March 21, 1882. American Steam (Iauc.e Qo}av\h\,j6 Oianion Strtft, Bostim, Afuss. Gentlemen,— Please forward by express, C. (J. D., one No. 12 and one No. 20 spring for Thompson Indicator, No. 240. Have been using your indicator for over a year, and consider it a beautiful instrument, delicate and fine in its action, and a pleasure to work with. If you have no No. 12, send No. 16 instead. Yours truly, JOHN SOBOLEWSKI. Cincinnati, Ohio, Mar. 8, 1889. American Steam Gauce Co., Boston. Gentlemen, — I have used Thompson Steam Engine Indicators for fifteen years, in fact, ever since they were first introduced, and have at all times and under all conditions of engine service, found them entirely reliable. In all my experience I have never had occasion to complain of the manner in which they performed, and if I were buying Indicators today I should buy the Thompson. I do not know that I can express my regard for these invaluable instruments in any stronger language. Very respectfully, JOHN W. HILL, C. E. Calumet & Hecla Mining Company. Office of the Consultinc, Engineer, Camuriugeport, Mass., Mar. 6, 1889. American Steam Gauge Co., j6 Chardon Street, Boston. Gentlemen, — I have to say that after quite an extensive use of the Thompson Indicator, I am persuaded that it is a most excellent instrument, and that my confidence in the same is proven by the orders from time to time sent your company. Vours truly, E. D. LEAVITT, Jr., Consulting Engineer. Sibley College, Cornell University. Ithaca, N. V., March 12th, 1889. Gentlcnun, — It gives me great pleasure to say that the instruments sent us have proved to be of most excellent quality, and so far as our work has given oppor- tunity to judge, of great .iccuracy. \Vc have used them on all kinds of work, and at speeds of rotation uj) to 300, and have found them capable of doing admirably. 'I'lie finish is excellent ai d the sizes and fits are all that could be desired. They have been very useful, both in class work and in making engine trials, and eminently satisfactory in all respects. We have had no dititkulties with them except such as have come from their use by inexperienced hands. When used for instruction an occasional accident is to be expected. They have withstood such injuries quite as well as we ought to expect, and have done more work and better work, even in such hands, than I had supposed possible. Very respectfully yours, R. II. THURSTON, Director. % 24 Oi.ivE Street. Afiiss. and one No. ao !r it a beautiful ritii. OBOLEWSKI. o, Mar. 8, 1889. )r fifteen years, s and under all the manner in ihould buy the instruments in HILL, C. E. Mar. 6, 1889. he Thompson and that my ne sent your «?■ En^neer, h 1 2th, 1889. sent us have ;iven oppor- >f work, and idmirably. be desired. 2 trials, and with them They have done more , Director. sm /Imerieai} St^am (^auQe $0., Bostoi). "^ Enw. r. Allis & Co., Rkliance Works, MiLWAiKEK, Wis., Mar. 14, iS.Sg. Amkrkan Steam riAU<;K Co., Boston, Moss. iieiitltmeii, — I have used all the prominent makes of Indicators, but verv' much prefer the Thompson, and believe it has more good points and less faults than any other instrument made. The easy changing of springs, good leading pulley for the curd, general convenience in handling, and last, but certainly not least, its ability to stand abuse, are some of the features that commend it to the practical engineer. Yours truly, IRVING H. REYNOLDS. ii>- PRICES OK THOMPSON IMPROVED INDICATOR AN1> EXTRA FIXTURES. Thompson Indicator complete, with one spring, in the instrument, one scale, two cocks, all necessary wrenches to use on the instrument, one screw-drivei, one bottle watch-oil, and Pray's "Twenty Years with the Indicator," all enclosed in a neat mahogany box Thompson Indicator, with the above fi.xturcs, and nickel-plated Extra Piston, J^-in. area " Springs " Box-wood Scales " Steel Scales " Cocks " Elbows Three-way Cock Single Carrying-Pulley Double " Parallel Rule Reducing- Pulley Clamps Metallic Cards Common Cards Detent Motion Pantograjih Planimeter , each per thousand $85.00 88.00 10.00 5.00 •SO 1.50 2-75 2.50 6.00 .60 1.20 7.00 25-00 3.00 15.00 7-50 3.00 10.00 1 vOO .S TEE L INI) ICA TOR. The regular Thompson Intlicator is made of Brass ahiiost entirely, and would not stand the action of the ammonia used in Ice or Refrigerating Machines. For these machines we make Thompson Improved Indicators all steel, to withstand the action of the ammonia. Price, all complete, with fi.xtufLS as above cuumerateil in price-list $ 1 40.00 Sw? .\ :/"* pm^rioai) Steam Oau^^ ^o., Boetop. TO ENGINEERS. Every man aspiring to the calling of an engineer should own and use an Indicator ; and, although the subject may at first seem too deep, it is nevertheless true, that any engineer can, with the assistance of the book of instructions sent with each instrument, learn to use the indicator with satisfactory results in a short time. To engineers we can allow special tcrtus^ and will furnislv particulars upon application. We solicit correspondence on the subject. The following parties use the Thompson Improved Indicator ; also a great many others who have procured the instruments of our agents : — Alex. Pollock, Engineer New York. John Roach & Son, Steamship Guilders . . New York. Charles W. CoiJeland, Consulting Kngineer. . . New York. William Lee C!hurch, Consulting Engineer . . . New York. Henry VV. Hulkley, Consulting Engineer . . . New York. A. & F. Hrown, Engineers New York. H. A. Rogers, Engineer ...... New \'ork. S. R. Kirby, Engineer New York. Delamater Iron \Vorks, Ste.imship Guilders . . New York. James Hoggs & Co., Engineers ..... New York. William Cramp & Sons, Steamship Huilders . . Philadelphia, Penn. T. H. Hickerton & Co., IJigincers Philadelphia, Penn. Harlan «S: Ilollingsworth Company, Steamship l!uilders,Wilmington, Del. The Pusey & Jones Company, Steamshij) Puiiders . Wilmington, Del. Ilerreshot^ Manufacturing C()m])any, Engineers . . liristol, R. \. M. C. Pignall, Mechanical luigineer . . . .St. Louis, Mo. F"rank 11. Pond, Mechanical Engineer . . . .St. Louis, Mo. Sanford & Covel Fall River, Mass. W. F. Sherman, Mechanical Engineer .... Lawrence, Mass. Whittier Machine C"ompany, Engine Puilders . . Poston, Mass. Washburn & Moen Manufacturing Company, Wire Manufacturers Worcester, Mass. W. C. Joiinson, Engineer Fitchburg, Mass. Schofield Iron Works ...... Macon, (Ja. A twood & McCaffrey, Engineers Pittsburgh, Penn. H. IL Westinghouse, Engineer Pittsburgh, Penn. Hill, Clarke & Co Boston, M.iss. Henry L. Einstein J5ound Brook, N. J. Renter & Mallory, Engineers Paltiniore, Md. United States Navy Department Washington, D. C. 26 A \ should own at first seem '"> with the instrument, loit time, vill furnish nee on the Indicator ; ents of our ^BB^ i^ flm^riGa9 8tean\ Q^ti^^ ^o., Bo8t09. 11 John W. inil, Consulting Engineer .... Cincinnati, O. 1 CiOulds & Ostrander, Fngineers North Star Iron Works St. Louis, Mo. Minneapolis, Minn. Lane & Hodley Company Cincinnati, O. Conant Thread (ompany (jrand Trunk Kailroad'of Canada Pawtucket, R. L Montreal. Frazer & Chalmers, Kngineers Chicago, III. Holly Manufacturing Company, Kngineeis Portland Company, Locomotive Builders Pennsylvania Railroad .... Lockport, N. Y. Portland, Me. Philadelphia, Penn. F. 1). Leavitt, jun., Mechanical Fngineer 1 William A. Ilarri.s, Engine Builder Cambridgeport, Mass. Providence, R. I. 1 (Jeorge T. Mcl.authlin & Co. 1 Randolph & Co '. (ieorge S. Beers, Engineer . Parke & Lacey, Engineers W. T. Garratt & Co., Engineers . Edward P. Allis & Co. . Boston, Mass. . Central City, Col. . New Milford, Conn. San Francisco, Cal. San Francisco, Cal. Milwaukee, Wis. Woodbury, Booth & Pryor, Engineers , . Frank E. Kirbv, Mechanical Engineer Rochester, N. V. Detroit. Mich. Atlas Engine Works, Engine Builders J. A. Lauder, Su])t. M. P. O. C. R. R. Calumet & IFecla Mining Company . F. R. Redpath, Consulting Engineer . Indianapolis, Ind. Boston, Mass. Calumet, Mich. Montreal, Can. Con.stant Mecse, Sugar Refining . Robert Wetherill & Co. [ American Rubber Company Robert Whitehill . . ' . Warden &" Hinckley .... American Tool and NLichine Company Cincinnati Water Works R. O. Moorhouse Nonantum Worsted C"ompany, John IL Mcdowan Company Hartford Engineering Company . Natchez Cotton Mills J Eliot B. Mayo California Paper Company . . Pacific Mills . . . . Brush Electric C!ompany W. Bingham & Co Rand Drill Company .... Massachusetts State Prison . Denver Foundry and Machine Company Erie and Wtstern Transportation Compan; \'ale Lock Manufacturing Company . Utica Steam Cotton Mills . George S. King Cambria Iron Company r San Francisco, Cal. Chester, Penn. Cambridge, Mass. Newburg, N. V. Chicago, 111. Boston, Mass. Cincinnati, O. Philadelphia, Penn. Newton, Mass. Cincinnati, C). Hartford, Conn. Natchez, Miss. Boston, Mass. San Francisco, Cal. Lawrence, ^L'lss. Cleveland, (). Cleveland, O. New York. Concord, Mass. Denver, Col. Buffalo, \. v. Stamford, Conn. Utica, N. Y. Pittsburgh, Penn. Johnstown, Penn. i 1 i % ^ ^ ^ — — 1 flm^rioap Steart^ Cjau^^ ^o., Bo8to9. C. Stewart & Son , William Berwick . S. A. Goodwin Morton, Kced & Co. .\(/,^V<' tSr» Kiump , Thomas Shaw Ilailowell Cotton Manufacturing Company St. Paul and Sioux City Railroad Company Chicago, Rock Island and Pacific Railroad Com John (jauge .... University of Minnesota University of Wisconsin Stephens Institute Massachusetts Institute of Technology Cornell University R. F. Power J. W. Hirkett .... Boston Rubber Shoe Company . J. Firmenich Crane Iron Company . Exeter Machine Works St. Louis Gas-Light Company North River Iron Works Arlington Mills . . - . Utica Steam Gauge Company Cleveland Rolling-Mill Company I). P. Stewart .... Buffalo Grape Sugar Co. Otto C. Woolf .... Whittenton Manufacturing Company Otis Iron and Steel C ompany Bass Foundry and Machine Comjjany M. F. Pennywell .... Henry Parsons .... H. S. Robinson .... Globe Mill Stei)hen Sanford .... G. Hall, jun Thomas Pray, jun. Door, Sash, and Lumber Company Bay State Iron Company Knc^wles .Steam-Pump Works George I >. Putnam \ Co. N. E. Weston Electric Light Co. E. L. Sanford .... Tilestou . Baltimore, Md. York, Penn. Pittsfield, Mass. Manchester, N. H. %^ '9 . ^A^^ M ml^ * 7T^ m m i'\'«< ;!.:: -.;'i;' _-_^ ^- . — ^^*j>«j^^ ^¥^ Pmr'iQaq St^am Qau^^ ^o., BostoQ. % Kagic lr(in WuiKh . F.au Claire. Wis. A. (;. I'hillips Hutte City, Mon. (). II. I'trry Lowell, Mass. Thoma.". II. ( onncll .... Lowell, Ma.Hs. T. W. lIuKo Duluth, Minn. t (ilumlii.nn M.iiuifarturing Company . Greenville, N. H. Charles A. Kichard.s .... Hridgeport, Conn. liarnal))' Manufacturing C^onipany Fall Rivei, Mass. P. n. .Skiflniore & .Son .... Ilridgeport, Conn. 1 Watts, <.'anii)bcll iV Co. Newark, N, J. Oeorge W. Wiliiani.s & Son . Charleston, S. C. Sterling Organ Company Itirmingham, Conn. 1 J. K. Clark Putte City, Mon. Canadian Locomotive and Kngine Compan_ S Kingston, Ont. Kohert Ixodnian . La layette, R. L R. 11. Thurston Iloboken, N.J. H. S. Nichols & Co Purlington, Vt. James A. I'latt Chester, Pcnn. J. F. Ridge way .St. Louis, Mo. I*. & F. Corbin New Hritain, Conn. N. O. Nelson Manufacturing Company St. Louis, Mo. C. II. North & Co F. Cambridge, Mass. E. (;. Studley & Co (irand Rapids, Mich. Walsh, I)c Koo & Co Holland, Mich. David Jenkins Sheboygan, Mich. E. H. Gowing Reading, Mass. Bowman & Kellogg .... Atchison, Kan. Green & Daniels Manufacturing Comp.'>ny Pawtucket, R. L Joyce, Cridland & Co . D.iyton, 0. S/i(iiig/iai C. C. Mill Company S/i(ini^liiii, China. James Sheriffs Milwaukee, Wis. The Bozrahville Company . Pozrahvilhi, Conn. China Manufacturing Company . Suncook, N. H. Schaffcr & Hudenberg .... Nev \'ork. Joliet Steel Company .... Joliet, III. (ieorge II. Gilbert Manufacturing Company . Ware, Mass. Webster, Camp & Lane Machine Company Akron, O. Southwalk Foundry and Machine Company Philadelphia, Penn. Anaconda Gold and Silver Mining Company lUitte City, Mon. Melrose Milling Company Evans ville, Ind. Rockdale Mill Northbridge, Me. Hope Company Hope, R. L Rhode Island Electric Light Company Providence, R. L R. M. Lodge . Philadelphia, Penn. F. H. Mayes Holyoke, Mass. Pacific Mill Lawrence, Mass. I. R. Scott Utica. N. V. Rhode Island Locomotive Works Providence, R. L Struther, Wells & Co . Warren, Penn. ^ ^ Jp)^ 30 o^l^k* 'Mf pm^ri(,39 Steam Q3U^(i ^ Bosto ? m }.. V. Osborne : . • . , .. Ncafi«' iV levy ..... .Newmarket Manufacturing (umpiiny . Jarvis Itarnet & Cd 1'.. r. Watson & .Son .... A. M, I»avy (irosvcnor Dale Company . (.■innnuT lMtf{ine Company . Charles I'!. J.iuks ..... kufiis K. Town.'^cnil .... Iron iiay .Maniilai tiiring Company Saunders ' 'otton Mill .... Rets, Shook iV Co ir. I, Nott J. II. He((.x II. \\';irrington ..... J.-ickson Foundry and Machine Company Monadnock Mill Nordykc and Marmon Company . Michigamme Company Wallace & Hrother .... Morgan Envelope Company Corliss Steam-Kngine Company . Frank A. Foster Daniel Ashworth D. W. Mur|)hy L. W. Cumpung.s John W. Turner Fldwin Stangcr E. C. Perry & Co J. Snow & Co. ..... Silver Spring Uleaching and Dyeing Company Edward Watson William H. Heinent & Son S. C. Forsaith & Co Fitchburg Steam-Enginc Company I'hcenix Chair I'onipany J. K. Foss S. M. Van Clief, M. E W. R. Smith New \ork Safety Steam-Power Company Exposition Cotton Mill A. J. Van Ness H. R. Worthington .... Lewis Johnson F. Van Winkle, M.E E. F. Williamson Merchants' Mill American Triple Thermo Union . .St. Paul, Minn. Phil.idelphi.t. Pvon. Ntwm.ukei, N. H I.anHing, Michigan. New N'ork. Detroit, Mich, (irosvcnor Dale, Conn. Cleveland. ( ». Cential Falls, R. I. Albany, N. V. Marquette, Mich. Saunilersville, Mass. Pittsburgh, Penn. Norwich, Conn. Westborough, Mass. Chicago, 111. Jackson, Mich, t'laremont, N. H. Indianapolis, Ind. Michigamme, Mich, lialtimore, Md. Springfield, Mass. Providence, R. I. New Haven, Conn. Cincinnati, O. Heverly, Mass. Waterbury, Conn. Mazeppa, Minn. Philadelphia, Penn. Dunkirk, N. V. Tuscaloosa, Fla. Providence, R. I. Newark, N. J. Philadelphia, Penn. Manchester, N. H. Fitchburg, Mass. Sheboygan, Wis. Reading, .Mass. New Vork. Oswosso, Mich. New Vork. Atlanta, Ga. New Vork. New \'ork. New Orleans, La. New Vork. Philadelphia, I'enn. Dedham, Mass. New \'ork. _**S_. .3 1 *t r f\(r\er'\Qat) Steam C^o^e ^o., BostoQ. If' J. K. UoKcrH \ Co. Mo!)tni>iniry lie Maiuifatturinn < ()ni|tai>y I'idiHoti I'^lfciric llliiniinator rompany • 'rhoiiu's Mannii)g, jiii). . \V. A. I lowland . W (',. Cuyli- \ Co. Wliiiiu-y Iron Wfirks Doiaii \ SiiiitI) Laurel lake Miiln Dodne Maiiufa< luring Company Novelty Iron Woi ks I'hd-nix Iron Company William Wriglit . Williams & Orifii Manufacturing Company I. K. Swift .... Irwin iV Ikissncr . lusmnaycr Company . A. L, Archambault K. M. lUirna, Kerconi (Jcldon llrotliers . John N. Paul AllenIiLiiy City Water Works II. Kirmistccr Goodytar Metallic Ruhher Shoe Company C. r. Williamson . Richmond I'ajjcr Company . W. n. Clohum, juii. Milwaukee Machine Company G. II. Morrison National Tube Works . Colt's Patent Fire-arms Manufacturing Compan Strong Locomotive Kngineering Company E. V. Davis .... John C. Froehlich & Co. S. E. Cobb .... Lynn Iron Company A. D. Traverr. Frank Mitchell J. Mendy Machine Works . Swain, Earle & Co. Cooke & Co. .... Anton IJorges Hraman, Dow & Co. Charles E. Rice Oshkosh Water Works Abiles, Cook & Co. Kensington Engine Woiks . Hancock Inspirator Company Warren A. Carr riiiludt'lphia, I'cnn Montnontcry, .Ma. Hrockinn, Masts. I leviland. < ». Lowell, \\,i*%. \i'\v < >rliMii-<, La. New < Irlfaii!*, La. Lc Sueur, Minn, r.dl River, .Mass. \\ ii.tiiaka, Ind. New Orlians, La. Trenton, N. J. N>.w!>iirn, N. \'. Sterling, 111. Ishpemiii;^, Mich. Galveston, Tex. Little R'uk, Ark. Philadelphia, Penn. Northfield, Mass, < 'olumbus, (ia. Middlctown, (). .Mlenlicny, Penn. Lon^d-de, V'a. Nauyatuck, Conn. Itiriningham, Ala. Providence, R. I. Utica, N. Y. Milwaukee, Wis. Pacific, S. C. McKeesport, Penn. llartfonl, Conn. Philadelphia, Penn. Pottsville, Penn. Haltimore, Md. Terre Haute, Ind. Birmingham, Ala. Cleveland, O. E. Killiiigly, Conn. San Francisco, Cal. Hoston, Mass. New \'ork. New York. Worcester. Lockland, O. Oshkosh, Wis. Little Rock, Ark. Philadeli)hia, Penn. Montreal, Can. Brockton, Mass. u 3« 1W)8. FBAY, JB., CoMWltlai SiiitaMer, 95 MILK BTRKET (Room 71), BOSTON. Boston, Mais., Oct. 84, 1890. BBtOAH BtBAM Gauob Co., Botiton, Mom. : ^d^m^lfff^y J- Your inquiry of Oct. 23, asking m« " to give you my till l^icpV the merits and demerits of the Thompson improved satbr, as mana&ctured by your company," is the first tame in a ^fassionilf career of mofe than twenty years that any corporation ir aslied me to tell them the outs of their instruments. [ Yon also malce a second inquiry ** with reference to what was my Iperfence with the Thompson indicators on the second official trial of ) United States steam cruiser "Baltimore," built by the William imp & Sons* ShiD and Engine Building Company for the United ktet government. Navy Department." rTo the second inquiry I can only answer in a general way, I was [iployed by the Wiltiafn Cramp & Sons* Ship and Engine Building mipany to inveHttgHte %Ke reason why the cruiser ** Baltimore" only ftde 8,977.2 horee-pfj^/er on her first official trial, and to suggest any iprovements which could be made, etc. After a careful examination ' the diagrams in the judge advocate's office of the Navy Depart- pent of the United States, at Washington, and some ten days spent ver the drawings, models, etc., in Cramp & Sftns' ship-yard, and on he ship examining the engines, I suggested certain changes which liould be made and which were afterward made by consent of Engineer- a-Chief Melville, of which alterations I had personal charge for Cvamp b Sons, by consent of the Navy Department. All of these ^changes rere inspected by the officers of the United States government then on luty at Cramp & Sons' ship-yard. When the alterations were finished, I was sent to the New York favy Yard, where I acted jointly with certain officers of the United States Navy Department, detailed by Engineer-in-Chief Melville, and »ndeT the immediate personal supervision of Chief* Engineer Dungan, ' the New York Navy Yard, and I assisted in the official test of the Thompson indicators made by your company for the Navy Departmentj for the cruisers "Baltimore" and "Philadelphia," preparatory to tlij instruments being sent to the ship to take the diagrams which wouh form the basis of setllement between the Navy Department and Orainpl & Sons, which was on the basis of $100 for every indicated horse- power made by the ship above 9,000, during the official trial run of foiirl consecutive hours. This statement is necessary in order to convey an! idea of the importance attached to that trial, as well as the test which preceded it, and also to enable me to answer your first question, from the circumstances which can only be brought out by answering the| second question first in order. The builders of the ship were under a guarantee to furnish 9,000 1 indicated horse^power, in which they failed on the first official trial, hv a fraction less than 23 indicated horse-power. * The engines were supposed to be capable of more than 10,000 indi- cated horse-power. It is unnecessary to say here what alterations! were made, or why ; but after the alterations were made in the engine.s, as is stated earlier in this letter, we commenced the test of each instru- ment and spring with the mercury column and steam gauge, these being the ''standards used" in the United States Navy Yjird at New- York, neither of which instruments were made by your company. Tery early in the test I filed an objection, which Chief Engineer Dun- gan, on careful examination, immediately allowed, and the instruments were then tested by a standard test gauge made by your company, corrected for the mercury column (in which we found eiTors). Then the coiTections of the corrected mercury column were worked out for the steam gauge, and found to be slight, and all the indicator springs were tested at five and ten pound intervals, according to the require- ments of the Bureau of Steam Engineering of the Navy Department, and upon this basis., after the official trial, all the corrections were made in computing the horse-power of the ship. When we came to test the low-pressure cylinder springs, I filed a written objection to the standard instrument furnished by its builders to the Navy Department, called a vacuum test gauge. This objection of mine called forth a very spicy letter from the Bureau, which was received only an hour before I left the Navy Yard with the instruments and the officers in whose custody they were to be sent on board the '* Baltimore." We went to sea Nov. 13, anchoring that night neai* the I>eiaware ;akwater. The aext day we went to the open sea with the ship for tr own test, and I ran the engines of the '* Baltimore '* with 126^ ^unds of steam at 118.6 revolutions for over two hours, during which le Chief Engineer 8. L. P. Ayres, in charge of the engineering rps, very courteously acceded to my request to have the assistants ^t the indicators on the engines of the " Baltimore " and take some rds, that I might get at the action of the valves and make any further mges which were necessary for the official trial that was to occur the llowing day. The action of the instruments on Thursday, to which Iference was made immediately above, was ererything that could be isired. After the United States officers had taken cards, which were indcd over to me for computation, the instruments were returned, each le to the custody of the man who was to manipulate it on the morrow, id the ship was headed back for her anchorage inside the breakwater. On Fi'iday, the 15th of November, we left the breakwater about six 2loek A. M., and went directly out to sea and van the ship from 7.25 7.55 under a full head of steam, when Chief Engineer Ayres cpj^.. jienced the official test of four hours. At twelve o'clock h., after running four hours and five minutes, offi- |al, not a single accident had occurred to any one of the indicators from ly fault of the indicator. Not a singe card was omitted, nor was a sin- le card soiled or lost, twelve indicators being used on both engines and )ur on the auxiliary machinery, diagrams being taken at intervals of teen minutes ; the whole 192 cards of main engines being formally tumbered and filed, not a single one of which contained a single inac- luracy which prevented its being computed. During that time two the indicators were seriously injured in the pencil bar, only by the irelessness of a man in passing up or down the ladders between the i|ratings in catching the leg of his pants in the pencil motion. These rere immediately replaced by others (Thompson's) to complete the [fficial record. Aside from this, no mishap occurred to any one of the Instruments. The high-pressure cylinder, carrying 123 to 125 pounds »f steam on the diagram, engines running at about 118 revolutions per linute, the auxiliary running from 700 revolutions per minute to as [ow as 32 strokes on the punii>s, some of the places being difficult of Recess, and others being where a man had to step over the indicator svery time an observation was made. Now and then a cord broke, and in one or two cases men lost a jrew, but these were replaced, as I had provided myself with them. The result, therefore^ of the test of the ThompBon indicators is fiiuItlesH, BO far as operation, adjustment, and accuracy are concerned. The derangements which occurred were not the fault of the instru- ments, their design or construction, and no trial of any naval vessel, either American or foreign, that I have ever attended, went off in so completely and thoroughly successful a manner as did that of the " Baltimore," so far as indicators were concerned, on her second official trial. In the previous official trial, which took place in September, 1889, Thompson indicators were only used to replace two instruments of anoUier make, used on the liigh-pressure cylinder, where a part of the cap blew off, crippling the instruments, and these two crippled indica- tors were replaced by two Thompson indicators which were on the ship, and they performed the rest of the duty in a perfectly satisfac- tory manner. The Thompson instruments were employed on the Bratherhood engines, making 700 revolutions per minute, which were used in the fire-rooms : they were used on the pumps, making 32 strokes, on the auxiliary condenser, on the electric-light engine, running at 375, answering perfectly in every place the requirements of the occasion. This is perhaps sufficiently explicit to answer your second question. Now as to your first inquiry, I have yet to come in contact with the first steam gauge or indicator in the United States to-day that is abso- lutely correct, and this refers not only to the instruments made by your company, but to those made by other companies as well. My personal experience in this matter is undoubtedly as good as that of any man living. Fourteen years ago the standards of a foreign government were corrected absolutely, and the objections which I filed with the Navy Department while in the employ of Wra. Cramp & Sons, on the United States cruiser "Baltimore," from the New York Navy Yard, abdut Nov. 26, 1889, have resulted in Engineer-in-Chief Melville, United States Navy, detailing a man who was thoroughly capable to visit the New York Navy Yard in January or February, 1890, to exam- ine into my objections to the supposed standards then in use, and the final result has been that the scale of the mercury column was found incorrect in itself, and that no part of the supposed standard instru- ment which was in use at the time my objections were filed with Chief Engineer Dungan now remain in existence, excepting the steei tabe 5 lining the mercury, the float, the wheel, and the index from which mercury soile was read. The vacuum te«t gftuge has been entirely indoned. A new vacuum gauge, of which I furnished the drawings, ))een arranged, with some slight modifications. The mercury ^umn has been corrected for latitude, height above the sea level, and gravity factor which must enter into all physical calculations, and la steam-engine indicator spring and a mercury column and a vacuum |umn are all within the realm of physics, it is safe to say that unless Stevens Institute and the New York Navy Yard have a near >roximation to a correct mercury column, there does not exist in the lited States to-day, Oct. 24, 1890, a mercury column or a vacuum ige that is correct. It must follow that the standards not being solute, the results of graduating - .y instrument whatever from these indards must necessarily he as incorrect as the standards (f). |Men who make instruments for sale usually consider that, if their itruments are as good as others, they are all right. [This does not answer your question fully, in my way of putting it. your instruments are incorrect, they are wrong, and that is exactly \y basis. Indicator springs give to-day, as a rule, from seven to as ;h'as thirteen per cent more power on an engine than they would re if the springs were correct. The indicated horse-power of the lited States cruiser "'Baltimore" by the instruments which had been sted, while the engines were running on Thursday, Nov. 14, com- ited 10»821 horse-power without correction. The official computation the power for the four hours' run was 10,119.68 horse-power. This ikes a difference of 701.32 horse-power, which was deducted from ^e reading of the indicator diagrams in order to make the correct lount of power exerted on the combined main and auxiliary engines that ship for that day. Had the indicator diagrams been absolutely )rrect, it would have added over $70,000 to the sum paid by the [avy Department to Wm. Cramp & Sons, which was $119,000, as »tween the guaranteed and the actual result of the second official rial, Nov. 15, 1889. It remains for you, therefore, as the oldest steam-gauge company in lis country, if I am correct, to put yourselves in a position to make bsolute instruments for commercial use, which can only be done by )ing t6 the very foundation with a man who is capable of working out le results, and you can have as nearly absolute instruments as any irvatcHry io the world. **^ ^e^' This questiou has never yet been considered in any industrial cor corn in the United States, except in an approximate way. It h a qaestion of several thousands of dollars to do this properly, and tlienl it may be a question of expense after that to arrange your springs, thej friction of the instrument, and various other physical questions, which| can only be done from a careful investigation ; but I hope that you wil at no late day take this question up and be able to offer A correct stesimj gauge, a correct vacuum gauge, and a hydraulic pressure gauge. In order to do this, the exact latitude of your factory must be ascertained, its precise height above the level of the sea, and then the absolute weight of a pound of mercury at that point, under a certain tempera- ture, and the gravity factor of the distance from the centre of the earth,! which makes a differance in the weight of a pound of steel, iron, mer-| cury, or water, must also be included, and correctly. These things have been made of np account, and my proposition to the Navy Department was at first ridiculed as far as courtesy would allow ; and Englneer-in-Chief Melville certainly deserves a great deal of credit for carefully looking into the matter afterward and availing him- self, for the first time in the history of the Navy Department of the United States, of all these quantities, and correcting the scales for lati- tude, gravity, and temperature. The lack of what Mr. Melville has done has been sharply criticised by the engineering profession the world over, and personally I congratulate myself as ah American that it has finally been thoroughly done. It is only a question of time when every concern that pretends to manufacture an indicator, steam gauge, vacuum gauge, mercury col- umn, or any other instrument by which pressure or vacuum is to be measured, must calculate the instrument for the precise spot on th .> earth where it is to be located and used. A steam gauge made .in Boston, with latitude, gravity, and temperature corrections, may be carried to any latitude or longitude in the world, and will correctly record the problems offered to it or observed from it. A pound of mercury is different in Philadelphia, New York, Boston, Portland, or London, Paris, or Naples. It remains to be seen now whether your concern has the enterprise to lead off in this, or whether some competitor will do it. The day has evidently pa^jed for selling instruments which have no foundation in fact, when submitted to physical observation and correction. Some ot our clock makers have found (his out by expensive experience. • lis will, fMrhaps, answer your questions, using more space tiian anticipated ; but to answer them fully and go into details would )rfere very seriously with throe books which will shortly be brought by my publishers, to which you and the general public will be jTerred for full particulars. Personally and professionally I have been accused of too much fovor- »m for the Thompson indicator. My reasons for such preferences as follows : — [It is over twenty-five years since your comi)aoy made the first pair Richards indicators, which I used. It has been my privilege to every instrument ever made that had any reliability. Years ago I [id, what I can to-dny say stronger than ever, that when I am on a aamship, a locomotive, or any other of the larger engines on which I illy work now, I use the Thompson indicator for the adjustment of ^Ives exclusively, from the fact that its delicate record of the chang- ^g of position of the valves is not equalled by any other instrument it I have ever yet seen or used. I use any indicator for general work which the parties have or desire use. I have tested the springs of all indicators, and am now on a imittee to further these tests, which has already lieen nearly one < sar in existence. I have to-day the largest engines in the world' to look after, and on sveral steamers, which for the last five years I have had charge of, ive invariably used the Thompson idiproved indicator made by your >mpany. I have only wished that they were absolute, or within an exceedingly [mall limit of absolute, as it would save a vast amount of time in com- >utation, and there is no reason why the instrument cannot be made practically absolute, in a commercial way, with ordinary care. The fact that five hundred indicators are used now where one was ised ten years ago would seem to be a sufficient incentive to do this rark. All of which is respectfully submitted. Yours truly, THOMAS PRAY, Jb. Note. — Ag to the capacity of the Thompoon indicators, I can only say that I have used the liompeon No. 1 on four hundred and thirty-five revolutions per minute (see "Twenty Years rith the Indicator," pages 162, 163), and the Thompson improved No. 2 on six hundred acd forty-two revolutions by the register (see "Twenty Years," pages 217-224). Since that time the No. 2 instrument has done work at Heven hundred and twenty revolutions per minute, by ctnai mechanical counting. », ' m f|*^ f\n\emaT) Steam (Jau^e $o., BostOQ. n TW H. T. Haitlctt A. \V. Stahl .... Grirtin Manufatiiiiing Coiiipaiiv Charles A. Hague \ovflty Machine Works . New NOrk. . fa Fayette, Ind. . < Irittin, Ga. . Chicago, III. . Kv.insvillc, Inil. I'ulltnan I'alaccCar (.'ompany ( liicagt), 111. M. V. I'ennyvvcll . Hamilton, O. W. H. jaiULson Wilson, Kan. Hurnhani Hanson . I'ovcr, N. II. James Krietf .... Boston Woven Ilc^e ('ompany .Magnoville, Cal. Boston. Hcrtram lirotlicrs . New \'ork. O. Matheson & ( o. Crook, Horner & Co. . New Glasgow, S. C. iiahimorc, Md. John M. Leach John Post, jmi., & Co. . . Kvansvillc, Ind, Boston, Mass. H. C. Burke .... . St. Paul, Minn. P. A. Noble .... John Kxton . - . . . .S])ringfield, Mass. Trenton, N. J. F. Grote & Co. New York. E. O. Kelsey .... Whitten Cotton Mill . Lowell, Mass. . Providence, R. I. Carnegie, Phip])s & Co. Paterson Association Stationary Canadian Pacific Railway G. A. Know .... Fred Wolff .... Remington & Henthorn Engl! le . Pittsburgh, Penn. Paterson, N J. Montreal, Can. Boston A'ass. Chicago, ill. Providence, R. I. Allen Print Works Providence, R. I. James Lockart .... Baltimore & Ohio K.R. Co. . Philadelphia, Penn. Baltimore, Md. Frank L. Cottrell . E. T. Dixon .... Union City, Fa. Millbank, S. D. Geo. Hornung Andrew Ringwald . Thomas M. Wilson J. A. Crouthers Cincinnati, O. Fly Mountain, N. V. Independ«;nce, Mo. New York, N. Y. V 1 Jas. Milne .... Montreal. s The W. Bingham Co. . Cleveland, O. '■ Reid & Creighton . Fred. Phelps .... Milwaukee, Lake Shore & Wester n Ry . Co. Fall River, Mass. Newark, N. J. Milwaukee, Wis. E. L Noxon .... Jamestown, Dak. C. H. McCutcheon Buffalo, N. Y. Strong & Tiowbridge . A. (j. Turner .... New York, N.Y. Willimantic, Ct. Jas. W. Birkett .... Brooklyn, N.Y. Blue Ridge Marble Co. Nelson, Ga. Walter Barnsdale . Los Angeles, Cal. i 'fm ^p~ /»m?ri8ai) S»ean> m Vi ;^ /^m,jun., editor of "The Boiton Jour- nal of Commerce," we publish licre- vvith one iiccoimt of the prjictical ap- plication of the ituhcator, wliich will show the imi)ortancc of its itppli- cation. " The diagrams illustrated in the present article are of more than passing intciest, and wcrt! taken from the engine of a man who places no value on its attachment. It is only ne( essary to say to the experienced man, that the diagrams were only taken when he found that something was the mat- ter which his engineer could not manage ; and this is only one of the numerous applica- tions of the value of the indicator, which the expert in its use is continually meeting. J2 The engine in ([uestion is a Harris-Corliss, • 14 inches diamete' of cylinder, 42 inches p length of stroke, 60 revolutions per minute ; the pressure in the boiler varying from 65 to 75 pounds. The diagrams A and ^are from the different ends of the engine; £ being the crank end, and // the headend. />' is one of these peculiar-looking diagrams which we freciuently meet with in actual practice, more esi)ecially from engineers who know exactly how to set their valves by a scratch or prick punch mark ; and they can tell exactly how she takes steam by watching the cut-off slide. The engineer in this case simply had to give it up ; and, if he had gone a few steps farther, his engine wovild have run the other way. The dia- gram ./ shows three lines as they were taken from the instruintnt, and they are most wretchedly irregiilai lines too. The steam line is as full of humps as a camel's bac k, and the notches and irregularities are the exact counteri)art of the movements or action of the steam as it is admitted to the cylinder. The admission line in itself is very late. The steam valve commences to open only after the piston has commenced its stroke. It does not open fully until after the piston has travelled several inches. The exhaust will be seen to be very late, both upon // and /i. It is comiiaratively small in its showing u])i>n A, from the fact that the diagram A shows a very mm.h lighter load than that of />'. The amount of power, 32.4-horse ^ 38 *T!3r ^ f\([\eriQa\) St^am (iau^? ^o., BostoQ. power, Kivtn on ./ it the mean of thrtc line-*; tin- larncxt amount t)ting plus 50, ann until the valves were in proper position. 'I'he toe at the enil of the expan- sion, at the conuneiu cment of the exhaust line, is an additional amount of work thrown away. This is only a fair specimen of the way that many cnj;infcrs get their valves; and they are always found in the . hands of those people who do not use the •^ indicator, and who frecjuently make the as- O sertion that they do not believe in the indi- '^ cator, for it is of no use. All such are perfectly welcome to their belief; and their emi)loycrs sometimes change their minds when the engine has been pro])erly indicated and adjusted by pcoiile who do believe in the indicator, and who know how to apply it, and read properly its r<^ ilts. "fand/^are from tht> very same engine after the indicator had been properly ap- plied, and the needed corrections made in the motion of the valves. The horse-power is almost idcntic.dly the same in both, the fractions being very small. The compres- sion is almost to a unit the same. The admission line is lost in the proper com- pressicm, and the steam line is carried as straight as ,1 line. The line of exjjansion shows V. i> little loss, and the diagram taken altogether is a very good product^n. It is needless to say that a very con- siderable saving of fuel resulted as the dittrrencc hctwct-n the engineer's setting, .•/ and /i, and thatof the man who api.lied tiie indicator, ( /). These diagrams are from actual practice, and were given us by Mr. Mosman of tlie Americen .Sieam Gauge Company. They were taken with 40 springs, and the engine at its regular work. Probably the (juestion never entered the head of the engineer in charge as to the result of the use of steam as in the diagi-ims ./ and /.'. The steam in ./is admitted in all sorts of tpiantity in the cnd.nvor of the regulator to reach alter and equalize the load which is done in the other end of the cylinder ; lail as the cut olf slides are 39 ■i* fim(^vr:aq St^am Qati^e Qo., BostOQ. ^^ set at B to cut off longer than is necessary, and at A are set shorter than they should be, it is simply impossible for the regulator to adjust the difference between them ; for the difference is so great that the regulator cannot measure it by the differential strokes of the cut-off slides, or the motion which is given them through the change of position of the balls on the governor. In this case the crank end of the engine is doing more than double that of the head end, and these motions of the head end are shown in the irregular steam lines by its race after the other end ot the engine ; and exactly in proportion as these lines differ from each other, was the resistance or the strain upon the dif .ent parts of the engine ; differing at each end of the stroke, making 120 times per ninute. In other words, the engine jumps 120 times a minute after its load, and the regulator is simply unable to adjust the difference, or, in other words, is attempting to accomplish an impossibility. The engine in this case is using something like forty per cent or more steam than would be necessary when properly adjusted, as is seen in the figure C and D ; and this is only another important lesson that people can learn if they will, but usually only learn when they are obliged to. And it is all the more to the credit of the indicator that it is able to show up, in the hands of an experienced manipulator, these points where pocket value is the point attained ; and in a case like this the amount of coal burned before and after adjustment is a factor that can always be measured in dollars and cents, and this is the standard of too many steam-users in quite an opposite direction." • •.'/ USING THE INDICATOR. To Attach to the Cylinder. The importance of the nidicator is now so generally recognized by all engine-builders, that nearly all first-class engines are sent from the shops with cylinder already drilled for its application. When no provision has been trade for the application of the indicator, holes must be drilled and tapped with not less than half-inch pipe tap, in such position in the side of the cylinder, that when the piston is at the ends of its travel, they will be as nearly as possible in the centre of the clearance space, and yet not be obstructed by the piston when at its extremes of travel. In drilling, great care must be taken not to allow any chips to get into the cylinder; and, when the heads cannot be removed, it is better to turn on a little steam as the drill begins to enter, in order to blow the cuttings out. It is usually most convenient to remove a strip or two of the lag- ging, and drill into the cylinder at the top or back side. Should the clearance be too small to allow of this, the tap inay be made directly into the head, which it is desirable to avoid, to bring the indicator into a convenient position ; the object being always to 40 ■^ ■ lag- *^ Pfnerioai) St^am (iau^^ Qo., Bostop. 1«t have the indicator connected as directly as possible to the cylinder : and in all cases where the circumstances will permit, the indicator cock should be screwed into the cylinder itself. When the tap is on the side of the cylinder, by use of nipples and elbows, which we can furnish, the indicator can be brought into a vertical position, the same as if tapped on top of cylinder. We do not recommend the use of a half-inch angle valve upon the end of a nipple, into which the indicator cock is screwed. Where the arrangement is to be permanent, it is much better to have an in- dicator cock for each end of the cylinder, which may be neatly cap- ped when not in use, preventing anything from getting into the pipe ; offering a much neater appearance, and, what is of more consequence, less obstruction to the steam. Obviously the most proper arrange- ment for indicating an engine is to have an instrument upon each end of the cylinder, from which simultaneous diagrams may be taken. This arrangement shows its advantages where engines are con- stantly changing their load, and where it is desired to test the equali- zation of the work between the two ends of the cylinder. When, however, a single indicator is to be used upon both ends of the engine, the best method is, to connect by means of side pipes and a three-way cock : the disadvantages arising fiom this indirect connection being more than counterbalanced by the facility with which the instrument can be switched from one end of the cylinder to the other without loss of but one revolution, and without disturbance of the connection with paper drum, and by the fact that diagrams are obtained from both ends of the cylinder on the same card. The turns in this Three-way Cock are made on a (juartcr- turn, and not on sharp angles, as in the old style. PRICE OF THREE- WAY COCK WITH SLIP .rOiyT TO AL- LOW EOti EXrASSlOX, ALL ... « . yiCKEL-PLATED - - $6. in its top. The stake socket must be level with the cross-head socket, and must be directly opposite the cross-head socket when the latter is at mid-stroke. The indicator cord is hooked to the centre peg /', and the stake should set at such a distance from the guides that the cord will lead off par-illel with the guides. Otherwise a guide pulley will be called for. When this rig is in motion, every point on a line cutting CD has a true motion parallel with the guides, varying in distance from nothing at /J to length of a stroke at C. It is only necessary to hitch the cord at a point on this line which will give the right amount of motion to the cord. This point will be near J), and within the range of adjustment of the strip 6'. This is as neat a device as could be wished for. I have seen Mr. Corliss's men hook on to an engine running -IT ?*.*; M mil 43 *? pmericar; St^am Qaa^e Qo., Boetor;. ^ at a good gait, without stopping. Mr. Corli.ss, I think, is in the habit of putting a permanent socket into his cross-head, and setting a nice standard in a floor socket. Infc()tk t(i ;• hoH/ontal position, Ko iis to sluit olV steam tVoin piston, an«l ••ppl) |>encii to the* paper to take the atin(»spheiic Mne. In apphinjir pencil to the carJ^ always use the horn-handle screw, to rej^uhite pressure ol" pencil upon paper to pnxhice as fine a line as possible. After the atniospherif line is taken, turn on steam, and press the pencil ajjainst card durinj; r»ne revolution. When the load is varying^ and the average horse-power reipiired, it is better to allow the pencil to remain during a number of revolu- tions, and to take the mean enictive pressure from the card. Remove card after dia^jram has been taken ; atid on the back of card make note of the following particulars, as far as conveniently obtainable: — 18 Barometer read*. DIAGRAM from M Engine. Diameter of Cylinder Built by Length of Stroke .. Revolutions per Minute Preuure of Steam, in lbs. , in Boiler Position of Throttle Valve Vacuum per Gauge, in inches Temperature of Hot Well Scale of Spring Inside Diameter of Feed Pipe... " " " Exhaust Pipe Valves Pressure Throttle... ..Regulator. REMARKS After sufficient number of diagrams have been taken^ remove the piston, spring, etc., from the indicator, wiiile it is still upon the cylinder ; allow the steam to blow for a moment throuj^h the indicator cylinder; and then turn attention to tha piston, spring, and all movable parts, which must be thoroughly wiped, oiled and cleaned. Particular attention should be paid to the springs, as their accuracy. will be impaired if they are allowed to rust ; and great care should be exercised that no grit or substance be introduced, to cut the cylinder, or scratch the piston. . ; Be careful always not to bend the steel bars or rods. : 51 11 w- /^merioaQ St^am (iau9? <5o., BostoQ. "t! The lu'al of the Mcain blown tlironuli thccvliiuliior tlii- indicator will be toimd to li;i\c driid it piifcitly, and the instrnnunt may be |)iit to^^cthir with (he assnranci' thai it is all ri-ady lor use when rc»|nired. Otiui items of precaiilnjii should be borne in mind (see Any enjfineer t.di easily repeat this operation without turther iuhtiuction. Ding ra »i A nalyn In . The Ibllowing definitions have been ^jiven to the diflerent parts r)f the diagram proper, an; i !! at.. /^m^ricaQ Stea/n Cjau^^ (^o., BostoQ. The diagram is pinned to a smooth board covered with a sheet of smooth paper, tlie pivot of the leg pressed into the board at a point which will allow the tracing-point to be moved around the outline of the diagram without Icjiiuing unnecessarily extreme angles between the two legs, and a slight indentation made in the line at some point convenient tor beginning and ending; for it is vitally important that the beginning and ending shall be at exactly the same point. The reading of the wheel is taken, or it is placed ,t zero, and the »/f in O iZ tracing-point is passed carefully around the diagram, following the lines as closely as possible, moving right-handed, like the hands of ^i^ 56 Jl^ ;ii /Im^ricai) Steam Cauf^ ^o.. Bostoi). ^ a watch. The readiiifi^ ohtainof! (by fln(lin<; tht- iHtVtMcuce hctAveon the two if the wheel has not l)ee!\ placed at zero) is the area of the diagram in square inches, which, multiplied bv tiic scale of the dia- gram, and divided by its length in inches, gives the mean etVective pressure. TAe Process of finding the Mean Effective Pressure by Ordi- nates. — Fig. 25 is too well known to require any detailed explana- tion at our hands; but we wish to call attention to a frecjuent niis- 2 take, namely, making all the spaces equal. The end ones should be half the width of the others, since the ordinates stand for the centres of equal spaces. 57 /)f[\eriQa9 Steam Qau^e ^o., Bostoi;. Ten is the most convenient and usual number of ordinates, though more would g^ve more accurate results. The aggregate lengf:h of all the ordinates (most conveniently measured consecutively on a strip of paper) divided by their number, and multiplied by the scale of diagram, will give the mean effective pressure. A quick way of making i :lose approximation to the mean effec- tive pressure of a diagram Is, to draw line aiy Fig. 27, touching at a, and so that space d will .qual in area spaces c and e, taken together, as nearly as can be estimated by the eye. Then a measure, y, taken at the middle, will be the mean effec- tive pressure. With a little practice, verifying the results with the planimeter, the ability can soon be acquired to make estimates in this way with only a fraction of a pound of error with diagrams repre- senting some degree of load. With very high initial pressure and early cut-off, it is not so available. FIG. 27. TAe Indicated Horse- Power. — IHP is found by multiplying together the area of the piston (minus half the area of the piston-rod section when gi-^at accuracy is desired), the mean effective pressure, and the travel o^ the piston in feet per minute, and dividing the pro- duct by 33,000. It is sometimes convenient to know the HP constant of an engine which is its HP for one revolution at one pound mean effective pressure. .,:< . , This multiplied by the mean effective pressure, and by its number of revolutions per minute, gives the IHP. » ft' 58 /^merieai; 8t^am (jau^e ^o., Bo8to9. THEORETICAL CURVE. Testing Expansion Curves. — It is customary to assume that steam, in expanding, is governed by what is known as Mariotte's law, according to which its volume and pressure are inversely pro- portional to each other. Thus, if i cubic foot of steam at, say, loo pounds pressure be expanded to 3 cubic feet, its pressure will fall to 50 pounds, and proj) ortionately for all other degrees of expansion. The pressures named are ''total pressures;" that is, they are reckoned from a peifect vacuum. A theoretic expansion curve which will conform to the above theory may be traced by the following method. FIG. 28. Referring to Fig. 28, having drawn the clearance and vacuum lines, as before explained, draw any convenient number of vertical lines, I, 2, 3, 4, 5, etc., at equal distances apart, beginning with the clearance line, and number them as shown. Decide at what point in the expansion curve of the diagram you wish the theoretic curve to coincide with it. Suppose you choose 59 i M l| l i l'!) l > i| ll >* md.',m^6m _. - 4^ firnvnoaQ 8tpa.5 Caduced by the following process : - — Taking a similar diagram to that used for the foregoing illustra- tions, we fix on a point A near the terminal, where the tv>tal pressure is 25 pounds.. As before, this point is chosen in order that the two curves may coincide at that point. Any other point might have been chosen for th during which steam at the pressure at A is being consumed. Hence the result obtained by the above rule is multiplied by AB., and the product divided by ab. 63 i';i w^ fitti^n^ar) 8t^am ^aa^e Qo., 603(09. "^ volume is 996. Thcn- : = 22.94 pounds water per IHP per To illustrate, Huppose the mean etVective presnure of the diagram to be 37.6 pounds, and the pressure at A 25 pounds, of ivhich the 37.()X99^>' hour, the rate that would be due to using an entire cylinder full of steam at 25 pounds pressure every stroke. But as the period of consumption is represented by BA, 6a being the stroke, the follow- ,. . . , 22.94x3.03 . , . mg correction is required : ^-^ — ^ — ^ = 20.15 ; 3.03 mches bemg 3-45 the portion BA, and 3.45 inches being the whole length 6a. This correction allows for the eflects of clearance as well as compression, since, i*" more clearance had existed, the pressure at w4 would not have been reached till later in the stroke, and the consumption line If A would have been longer. But such a rate can never be realized in practice. Under the best attainable conditions, such as about the load indicated on the diagram, or, more, on a large engine with steam-tight valves and piston, and well-protected cylinder and pipes, the unindicated loss will seldom V>e less than 10 per cent; and it will be increased by departure from any of the above conditions to almost any extent. It will increase at an accelerating ratio as the load is diminished, so that such calculations applied to light-load diagrams would be deceptive and misleading; in fact, they have but little practical value except when made for comparison with tests of actual con- sumption, for the purpose of determining the amount of loss under given conditions. FIG. 31. J^/pe Diagrams. — Sometimes when considerable loss of press- ure appears on comparing that shown by the gauge with the highest initial pressure shown by the diagram, it will be found very instruc- 64 ^ \t f(lf\er'iQ^[) $t^9a\ Qaa^^ ^o.. BostoQ. tivi' to connect the indicator witu the Kti-am pipe in addition to itn UHiial connections. A | inch or ^ inch pipe will he Nuthcii-nt for the purpose, with a valve or cock as close to the indicator as c*»n- venient. Me|V»re or after taking the cylinder dia^^rams steam is admitted to the instrument from the steam pipe and the pencil applied, when a diagram sitiiilar to that shown ahove the cylinder diagrams in Fig. 31 is produced. In that figure it shown that there is scarcely any loss of pressure between the pipe iitui the piston, all tlie loss being in the pipe at the beginning of the stroke, though a little .i-sfi of pressure between the pipe and piston appears as the point uf cut otl is approached. Sometimes, — fre(|uently, in fact, — the pressure in the pipe rises above that in the boiler for a moment alter cut otf, but such extra pressure will be readily recognized by its falling again before the next admission. IMiis is due to tlic momentum of the steam when suddenly cut otl', and its etVects will be greatest with long, straight pipes. When the pipe diagram is above and clear of the cylinder dia- grams at all points, the space separating them is the measure of the loss of pressure due to passing tludugh the cylinder ports and all passages between the point from which it is taken and the piston, while the variations of pressure in the pipe diagram indicate the loss due to passing through the pipe, allowance being made, as above explained, for the rebound ol pressure above that in the boiler, when it is shown to exist. We shall he pleased to furnish electrotypes of the Thompson Improved Indicato^r^ or any other instrument illu trated in this catalogue to parties desiring them to use in other ratalogues. 65 «! ■i OT' /tmericap Steam Qaa^e ^o., BostOQ. AMSLER'8 POLAR PLANIMETER. ;: r FIG. 32. There are several other instruments which are used as accessories to the indicator, and whicli greatly facilitate the using of the instru- ment, one of which is Amsler's Polar Planimeter, as shown by the accompanying cut, for measuring the area of indicator, diagrams. By using this instrument, the whole work of measuring a diagram can be done in one minute. Engineers who have many indicator cards to work up cannot atlbrd to be without a planimeter. 66 /)m^rka9 Steam Qau^^ ^o., 605(09. ^ IHrfrtioHM for t'ltlni/ the tnBtrHiHfHl. IVcHi thr poitU y1 sli^litly into tlu- paper, not clear throu);h, in Niich position that the* tracer />* will follow the dvHircd line with- out hrin^ini; the roller C against any projection. The roller ntUHt move on a contiiuionH flat Htirface. It iH also well to tasten the dia^^ram to a drawing-hoanl, or some other flat Hurfacc, hy means of pins or sprinf^H, to prevent it (Vom slipping. Mark a startin^^-point at any point on the outline of diagram J)^ set the tracer on that point, and place zero on the roller so it exactly coincides with the zero on vernier E. Now trace the line, moving in the direction travelled by the hands of a watch ; stop at the starting-point, and take the readint^. 1st. Find the highest llgure on the roller that has passed the zero on the vernier, moving to the left, which we will assume to be 4 ; now the construction of the instrument is such that each figure on the roller represents an equal number of s(|uare inches. 2il. Find the number of completed divisions betwi"' 4 on the roller and zero on the vernier, which we will assume to be 5. 3(1. Find the number n\' the mark on the vernier which coincides with some mark on the roller, which, in this case, may be 6. We now have the exact reading, 4.56 or 4iVo '"^bes area. In measuring diagrams of more than 10 inches area, add 10 to the result. To those who are perfectly familiar with the instrument, it is not necessary to place the zeros so they coincide; but take the reading as it is, and subtract it from the result. Should the second reading be less than the first, add 10 to the second reading before making the subtraction. For instance, should the first reading be 8.42, and the second reading 2.68, add 10 to the second reading, thus: 2.684-10=12.68 — 8.42 = 4.26 square inches. If the area to be measured be very large, divide it by lines into areas of less than 20 square inches, and take separate measure- ments. If the drawing be to a scale, multiply the result by the square of the ratio number of the scale. Should we desire to find the area of a plan containing 5 square inches, drawn to a scale of 100 rods to the inch, we square the ratio 67 fim^mai) Steam Qau^^ Qo., Boetop. "^P number, and multiply by 5, thus: 100x100=10,0x50x5 = 50,000 square rods. In using the planimeter for indicator diagrams, for which it is specially adapted, we find the area of the diagram according to the foregoing directions, which we will assume to be 2.48; we now measure the length of the diagram parallel with the atmospheric line, which we will say in this case is 4 inches. Now divide the area by the length ; the quotient is the mean or average height of the diagram in inches, which is .62 inch. This we multiply by the scale of the indicator, which we will assume to be 40 ; the product gives us 24.8 pounds mean pressure each square inch of the piston. Expressed arithmetically, 2. 48-5-4=. 62x40= 24. 8. It can also be used for measuring any regular or irregidar plot or diagram. The following is from "The American Machinist" of Dec. 27, 1879, by Chordal : — "The Polar Planimetkr. — This little instrument, of which the cut is about three-fourths size, is used as the cut shows. The point A is stationa'-y, and the tracer B is moved once over the outline of the diagram. The reading of the index wheel Cthen shows the area of the diagram in square inches. This reading divided by the length of the diagram, and multiplied by the scale of the spring, gives mean pressure of the card. The demonstration of the action of this simple instrument would require too much space, and I will defer it. The instrument will stand any possible test for accuracy, and eliminates all those ever-present chances for error involved in the human measurement of many ordinates. The time required to ascertain the mean pressure of the most ragged diagram need not exceed, when the planimeter is used, one minute. This instrument is one of the indispensables to an engineer having many cards to work up, and is a real labor-saver. The planimeter is the invention of Professor Anisler, a German, and, as made in Europe, was intended for comprehensive utility in measuring areas, and for giving results in sundry units, such as inches, feet, acres, and the long list of foreign superficial units. This involved considerable complexity in the instrument, and, of course, a high cost. F"ew in this country ever heard of them, and but two or three steam-engineers possessed them. The foreign makers sent horrible translations of the directions for use with the instruments. Among other things, this translation stated, that, ' as the principle of the instrument is a secret, there is no danger of others being put on the market.' This clause was the cause of the instrument being made in this country. It was a dare. Mr. James W. See, an engineer in Ohio, took the thing up, got at the principle, redesigned the instrument so as to make it specially useful for such work as indicator cards, and had quite a number made, which he sold and presented to engineers. They are now made by the American Steam Gauge Company of Hoston, and, I am informed, are sold with nearly all indicators. A similar form of the instr.nnent is made by EUiott Ikothers, London; but it lacks the simplicity of the American one." 68 w /tm^rieap 8tean\ (jau^^ (^o., Bostoi;. ^ The planimetcr is furnished in a nice morocco box, lined with velvet, and can be sent l)y mail to any place in the United States for nine cents. The enormous sale we are having of this instrument shows how fully it is appreciafed, we being the sole manufacturers in the United States. Amsler's Polar Planimeter was awarded a silver medal and a diploma at the Cincinnati Industrial Exposition, Oct. 8, 1881. After the second official trial of tlie new U.S. cruiser Baltin^ore, which took place in November, 1889, the computations of these diagrams were to be made with the planimeter instead of by the old fashioned methods. The diagrams from the second trial were to be computed first by the U.S. navy officers and afterwards by Mr. Thomas Pray, Jr., of Boston, for the builders of the ship, the Wm. Cramp & Sons Ship and Engine Building Co. During the com- putation by the navy officers, some questions arose which resulted in their pronouncing tiie planimeter made by this company incor- rect. We publish here, by permission of Mr. Pray, a copy (»f his solution of the question at that time ; also, his own comments on the subject, which were furnished by him, on reqiiest. "The decision with refertnce to the planimeter is only another evidence that capable men sometim -s disagree, and that men who mean to do exactly right some- times make mistakes. This jjow-wow about the i)lanimeter, as ap!)lied to the diagrams of the Haltimore is of a great deal more importance than the average man supposes. " When it is taken into account that on th • engines of this ship one pound of mean pressure on one single engine is worth $;io.ooo, it is evident that correct com- putation of the cards ceases to be an amusement and becomes a veritable fact. " I have, therefore, taken a personal int»'resf of no small amount in demonstrat- ing to my own satisfaction that your jjlanimeter was cither right ( r wrong, without any ifs, buts or ands. Here is a little solution that I give you my permission to print, only stipulating that you shall C've me credit for it. It is this : if the plan- imeter is not correctly used it is incorrect in its rt. ults to a very small extent. If correctly used, I have found, in the work with reference to the U.S. cruiser Haiti- more, which I am now doing in Philadelphia for the W m. Cramp & Sons S. and E. B. Co., that these errors are larger in the person th-^i in the inttiumcnt; that the instrument is cnp. iWe of measuring an indieator diagra.n nearer correct than the person 's of traversi.ig^the same line the second or third or any other number of times, and coverin;^; absolutelj the same area. *t i*;t w^ P{t\er\Qat) Stea/n (jau^e ^o., Bostop. ^^ "This makes the actual error of the inatrunicnt, by careful running, less than I in 17CX). Here is the way to get correct results : — J 1 "Take any piece of cardboard, Bristol board or strong paper, draw on it the line as in the figure A, any length you please, preferably about 8 inches long, at right angles to the line A, draw the line H, which may be any length you please, wider thiin the total width of the paper on which an indicator diagram is taken, but the line H must be drawn at exactly 4.34 inches from the point on line A where the other line intersects the long one, or, in other words, the distance between A and H must be as nearly 4 5-16 inches as can be laid down by an ordinary rule. Then put the point of liie planimeter at A and put the card to be computed so that half the height shall be above and half below the line A, and half the length to the right and half to the left of the line li. Then if the reading pointer of the planimeter is correctly manipulated, the exact area of the figure will, in every case, be ob- tained, so long as proper care is exercised in reading. " This will allow the use of high pressure, condensing, compound, locomotive, air pumj) or any other kind of card to be ctnnputed ; and if the lines are drawn in ink and the distance is carefully measured and the planimeter properly managed, they will be found far nearer correct than the power of the person using them to repeat his own measurements absolutely. This was the result among the naval engineers, after the use of a large Amsler's planimeter, obtained from the navy department, and the actual difference in measurement of the same diagram between their and my own large Amsler was i in 2400, and the difference between my own large Amsler and my American Steam Gauge Amsler, No. 231, which I have used for several years, and three other American Steam (lauge Amslers, loaned for the pur- pose, was a little less than i in 1800 for the whole four; but by distorting the posi- tion of the instrument with reference to the figure, without the use of the simple diagram enclosed herewith, the errors of the little Amslers were as high as i in 560, and this error immediately vanished w'len the position of the same instrument was corrected by the two black lines drawn on a piece of drawing paper, the same as is referred to in the figure above. " It is not necessary that the diagram should be placed perfectly parallel with the line A, but it may be placed at any angle to either line, so long as the centre of the area to be measured is kept over the intersection of the lines A and B. This is particularly the case whenever the diagrams are taken 4 3-4 or 5 inches long: or the tliagram may be inverted and the vacuum line or the atmospheric line be nearest tile instrument, or above the line A instead of below it. " You have my permission to make use of this, by credit, in any way you see fit which is for your advantage and for the beivefit of the thousands of men who are using your instruments." 70 t I I m ;e; 1 11 ;e; pmeriQap St^am (^au^e Qo., Bostoi^. ^ TESTIMONIALS. [copy.] Navy Dkpartment, Hureai' ok Stkam-Kncjinkkrinc;, Washincton, April 7, 1879. Sir, — In obedience to your order of the 5th inst., we have carefully examined the Polar Planimeter, submitted by H. K. Moore, and find it to be identical in design with Amsler's improvement on the original instrument of Appenkofer, but unpro vided with attachments for changing the scale, or for recording the revolutions of the index roller. The instrument submitted is light, neatly and well made, and all its working parts accurately fitted, and capable of delicate adjustment. It can be readiiy manipulated by any person of ordinary intelligence ; and, in our opinion, its use will greatly facilitate the work of measuring the areas of irregular figures, and will be particularly valuable to the Hureau for determining the mean pressure of indicator diagrams. Very respectfully your obedient servants, H. W. FITCH, Chief Enghuer, U.S.N. DAVID SMITH, Chief Kngincn; (\S.N. H. WEKSTER, P.A. Engineer, U.S.N. To Engineerin-Chief Wm. H. Smock, US.N., Chief of Bureau Steam-Engineering, Washington, D. C. Icopy.l Office ok John W. Hill, Mechanical Enoineer, CiKciNNATi, O., Dec. 29, 1879. H. K. Mooee, Esq., Boston, Mass. Dear Sir, — Upon my return frr-m St. Louis, last week, I found your kind remembrance of the writer in the shape of a new planimeler, for which you have my sincere thanks. I have carefully tested the instrument, and it varies but-j^Voinr '" the circuit. Very sincerely yours, JOHN VV. HILL. ... By its use, diagrams may be carefully and correctly measured in one minute, everything l)eing taken into account, and the actual area found. THOMAS PRAY, Jr. PKJC'JS or THK PLAJflMKTEH, ALL S H.KKL-Pl.Al^.i,, Afilt IS A VEhVET'LINlCIt BOX . . $lff,or 7' io^ 1*^*? /tfn^rieaQ 3^®^^ (jau^^ ^o., BostOQ. RICHARDS PARALLEL-MOTION INDICATOR. FIG. 33. This indicator has been long and well known with the engineer- ing public. It is not adapted for high-speed engines, but is per- fectly reliable and accurate for engines making less than eighty revolutions per minute. PRICE , . . $85.09 Extra springs, scales, cocks, elbows, etc., same price as those u '^: i % ' !. .1 THOMPSON IMPROVED INDICATOR. v/ ez-K--