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October 22nd. You are respectfully requested to contribute. 
 
 (Alt rights reserved.) 
 ADVANCE PROOF~(Subject to rmtion.) 
 Thl. proof t. «ent to you for discussion only, and on the 
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 (iCattAdinit jloc«t« at (&m (ftnflinrew. 
 
 INCORPORATED 1887. 
 
 TRANSACTIONS. 
 
 N.B.-Thl. 8«i,ty, „ , body, does not hold ifelf re.pon,ibl. for th. f„u «>d opinion, 
 stated in any of its publioations. 
 
 THE STEAM ENGINE. 
 
 By W. H. Laubib, M. Can. See. C. E. 
 
 To be read on Thursdiiy, October 8th, 1891 
 
 In tracing up the hi.tory of the steam engine, considered a« a 
 tramo mechanrnm, we lind that the modern steam engine has 
 been fully developed within the last 200 years-orsincelhe year 
 I .90, and Us advance during that time, may be divided into four 
 stages, 01- periods of 50 years each. 
 
 lfi90_FiR8T Stage ok Period— 1740. 
 
 As a .ule the great majority of inventions when first intro- 
 duced to the public are more ,.r less complicated and cumber- 
 some, the object of subsequent improve.nents bein^ to simplify 
 and ,-educe the nurr.ber of parts. To this rule tho^Mm engine 
 torms a striking contrast, it having been first introduced in its 
 simplest form, each consecutive stage in its history being marked 
 by an increase in the number of its parts and in the complica- 
 tion ct Its construction, and a corresponding reduction in the 
 consumption of steam per horse power. 
 
 About the year 1690, Denys Papin invented the Hrst steam 
 engine, or rather steam cylinder with a piston. When rir.t 
 introduced, the cylinder performed the functions of steam boiler 
 steam cylinder, and condenser. It was operated as follows ~-\ 
 ^mall quantity ol water was placed at the bottom of cylinder 
 a hre built beneath it, the steam formed raisins,^ the piston ttl 
 the top of cylinder, where a latch enga.^od a notch in the piston- 
 rod holding it up until it was desired that it should drop. 
 
 The fire being removed, the steam condensed forming a vacuum 
 below the piston, the latch being disengaged the piston was 
 .Inven down by the pressure of the atmosphere, raising a weight 
 which ha.l been in the mean time attached to a rope from U.e 
 piston rod over pulleys. This machine made one stroke per 
 "^Z^':^ . '"'■""^'' '•"'^'"'•'to.l chat a 24" cylinder would raise 
 ,000 lbs., four feet, per minute, or developo nearly one horse 
 power. I J 
 
 A few years after his first invention Pajjin made another im- 
 poitant invention which increased the efflcioncy of his en-ino bv 
 using a seperate steam generator, as described at the time, a kind 
 ot tiro box steam boiler, in which the fire, completely Kirroundetl 
 by water, made steam so rapidly that his engine could be driven 
 al the rate of four strokes per minute by the steam supplied 
 from it. '^ 
 
 The Papin engine was further improved and developed by 
 Newcoinen, Bcighton & 8moatoii, producing a combinMtio,, .if 
 several ol the elementary parts of the modern engine, making it 
 
capable of transmitting^ force directly to the resistance to be 
 overcome, the object boinj? to make it better adapted to pumping 
 mincH, &c., the piston being connetlod to the pump by means of 
 the overhead beam. 
 
 During the tirst period of development the steam engine was 
 used almost entirely as a pumping machine, and might more 
 properly be considered an atmospherio engine, as steam was 
 used only to produce a vacuum, the powoi- being supplied by the 
 pressure of the •ilmosphoreand that on one Mo of piston only. 
 
 1740— Second Period— 1790. 
 
 The second stage or pei'iod in the devuiopraont of the steam 
 engine may bo considered enliroly as the work of James Watt 
 (that stage being marked by more rapid development than any 
 other). He, among many other important inventions and im- 
 provements, add,Ml to the engine of the tirst period, the separate 
 condenser, air-pump, fly-ball governor, crosshoad, guides, par- 
 allel-motion, rotary-motion, double-action, and non-condenHing, 
 high-pressure steam engine. With these additions completed, it 
 embodied nearly all of the cssontial foatuies of the modern 
 engine. He also discovered the advantages to be derived from 
 the use of steam expansively, and specihed a cut-oft" at J stroke 
 as the mOHt ecomomical. This discovery has proved to be most 
 important in the development of the economical application of 
 steam, althoiigii shortly after its tirst introduction, it haJ to be 
 discontinued, owing to the trouble and annoyance Watt exper- 
 ienced with proprietoi's and their engineers altering the valves. 
 He intended to rosutoe it at a later period wnen workmen of 
 greater intelligence and reliability could be found. 
 
 1790_Third Pbriod— 1840. 
 
 The distinguishing feature of the thii-d period was the intro- 
 ducing of the compound, or two-cylinder engine. Although the 
 lirst compound engine was invented in 1781, by Jonathan Horn- 
 blowcr, it was not a success, owing to the steam i)ressure used at 
 that time being so low that uo advantage was gained by the 
 device. 
 
 In 1804 the Hornblower compound engine was again intro- 
 duced by Arthur Woolf, and, by using steam at a higher pressure, 
 and expanding it from six to nine volumes, a very great advan- 
 tage was gained over the Wiitt and other engines of that time. 
 Other engineers followed in Woolf V footsteps, designing moditi- 
 cationn of the compound engine, so that by the end of the thin) 
 period which we have considei'od, the compound had become a 
 standard engine. 
 
 1840— Fourth Period— 1890. 
 
 The most important features in the development of the eco- 
 nomical use of steam during the fourth period, or that of the 
 immediate past, has been the invention and introduction of the 
 automatic engine, and the system of expansion (in two cylinders 
 during the former period) being carried to three oi' four cylinder.-. 
 
 The fli-st automatic engine was invented by George II. Coriis~, 
 about the year IH.iO. An aljustable drop cut-off had boon in 
 vented ten years earlier by F. E. Sickeis, but Corliss was the firsi 
 to attach the governor directly to the cut-otf i.iechanism, and, \>y 
 so doing, I'egulato the speed of the engine by adjusting the point 
 of cutoff, and also using titoam in the "ylinder at nearly boiler 
 pressure up to that point. 
 
 To form an idea of the advantages of modern steam practise as 
 compared wilh thai of the earlier stages of its use, and to note 
 tlie advance made during the lour ditferent stages that wc have 
 considered, wo will have to assume an avei'age indicator card 
 from x;ach period from the inform.ation we. hnvo, and, by annliz- 
 ing each, form a compaiison. 
 
 2 
 
For that purpose we will assume a atoam cylinder of 13f" dia- 
 meter, or a net area of 144 squuro inches in ench, and for the first 
 period a guage pressure of 1 lb. or 16 Iba absolute— i.e. 
 
 Oabd No. 1. 
 
 Allowing 1 lb. to raise weight of piston, rod, etc., and that a 
 vacuum be produced equal to a M. E. P. of 7 lbs. below the 
 atmospheric line, and allowing a piston truv ol of 100 f9et per 
 minute, the power developed will be 144 X 100 X 7 = 100,800 
 :- 33000 = 305 horse power, and the theoretical consumption of 
 steum will be 100 cubic feet per minute or 6,000 cubic feet per 
 hour, and as steam at l« lbs. absolute weighs •0411 per cubic 
 foot, then 6000 X 0411 = 246-6 lbs. of steam per hour, and as 
 we have found that the power developed will be 305 H. P. then 
 2466 — 3-05 = 8085 lbs. of steam per hour per H. P, as the 
 consumption for Ihe first period. 
 
 For the second period with same cylinder area we will assume 
 200 feet of piston travel. (Steam at this period was used above 
 atmospheric pre,s8uro, and double acting.) 
 
 Cahd No. 2. 
 
 For this card wc will assume a steam p;es8ure of 15 lbs and a 
 terminal of 26 lbs. absolute, a M. ii. P. of 224 lbs., the power 
 developed will bo 144 X 224 X 200 ~- 33000 = 195 H. P. and 
 the amount of steam consumed will be 200 cubic feet per minute 
 or 12,000 cubic feet per hour and as steem at the terminal 
 pressure, viz. : 26 absolute, weighs 0650 per cubic foot then 
 12000 X '0650 = 780 lbs. per hour, this divided by 19-5 = 40 
 lbs. of water per hour per H. P. for the second period, or about 
 one-half of that required to develop ■ horse power 50 years 
 earlier. 
 
 For the third period a still higher steam pressure was used 
 and expansion carried to 6 and 9 volumes. ' 
 
 Cabd No 3. 
 
 For this cai-d we will assume, sitme eylin.ler area, 400 feet 
 piston travel 40 lbs. steam pressure expanded 7^ volumes and a 
 M. E. P. of 16 lbs., the power developed will be 144 x 4"0 X 16 
 4- 33000 = 27-93 H. P. and the steam consumption measured 
 from terminal of !) lbs. will he 400 X 60 = 24000 X -0239 ~ 
 27-93 — 20-5 lbs. of steam per hour per horse power, or about 
 one-half of the cost of same power during second period and one- 
 fourth of cost of same power during first period. 
 
 For the fourth and last period of steam engine practice we have 
 in many instances a steam pressure of 200 lbs., also cylinder steam 
 jacketed with superheated steam, and other refinements that tend 
 to reduce steam consumption. 
 
 Cabd No. 4. 
 
 For this period we will assume a steam pressure of 150 lbs 
 expanded 20 volumes, a M. E. P. of 31 lbs. referred to sam'e 
 cylinder area as in other cards, viz. 14t inches and a piston travel 
 of 800 ft., this will develope 108 horse power, and the steam con- 
 sumption will be abcut 10 lbs. per hour per horse power. 
 
 In reviewing these four periods we have in the first, steam used 
 at a little over atmosphere pressure, without expansion, a piston 
 travel of 100 ft. per minute, a power developed of 3.05 H. P.. at 
 a cost of 80 lbs. of steam per hour per H. P. 
 
 In the second period we have steam at 15 lbs. .ibovo atmos- 
 phere, without expansion, a piston travel of 200 it. pur minute 
 a power develoi)ed of l<t5 II. P., with a steam consumption of 40 
 lbs. pei- hour per II. P. 
 
 In the third period, we have steam at 40 lbs. above atmosphere, 
 expanded to 7J volumes, a piston travel of 400 ft a minute, a 
 power dcvclopea of 2793 II. P., with a steam comsumption of 20 
 lbs. per hour per H. P. 
 
 3 
 
And in the fourth period we have steam at a pressore of IBO 
 lbs. above atmosphere, expanded to 20 volumoM, a piston travel of 
 800 ft. per minute and a power develop*! of 108 H.P., with a 
 a ateam consumption of 10 lbs. per hour per horse power. 
 
 Cyi~ An«A. 
 
 Piston tr'vel. 
 
 Steam P. 
 
 Power. 
 306 
 
 Theoretical 
 Consumption 
 
 lit.... 144 
 
 100 
 
 1 
 
 80 lbs. 
 
 L'nd... '' 
 
 200 
 
 10 
 
 106 
 
 40 " 
 
 Srd... " 
 
 40O 
 
 40 
 
 28-0 
 
 20 " 
 
 4th.... " 
 
 800 
 
 160 
 
 108. U 
 
 10 " 
 
 From the^e figures we find that the tendency through all the 
 different periods, has beun increased stoam pressure, and higher 
 ratio of expansion or hi,%'h initial and low terminal, i.e., theoretic- 
 ally the higher the initial and the lower the terminal, the greater 
 the economy. But practice has estnblishol it to be a fact thrt 
 the higher tho initial and the lower the terminal, or the greater 
 the ratio of expansion in a single cylinder, tho greater the loss 
 both by clearance iind condensation. 
 
 Clearance in tho space between the piston and valve face when 
 :in engine is on it« centre (including area of ports, passages, etc.) 
 which has to bo tilled with steam each stroke before the piston 
 moves forward, and is computed by the percentage its volume 
 bears to the area of piston raullipliod by the length of its stroke. 
 This percentage varies from 2 p.c. in long stroke engines to 15 
 !ind even 20 p.c. in short stvoko engines. 
 
 The loss by clearance is quite a serious one where expansion is 
 carried to extremes in a single cylinder and also in short stroke 
 engines, where it forms a high percentage of the volume of 
 cylinder. 
 
 If we take as an illustration a condensing engine card, with 
 steam pressure 80 lbs., expanded 20 volumes without loss by 
 clearance, we get a mean etlective pressure of 15 lbs. 
 
 (^'aed No. 6. 
 
 Then expand the same volume of steam in a cylinder of s;imo 
 area, but with 5 per oeiil. clearance, we tind that the card shows 
 the steam to have been cut otf at the time the engine was on its 
 centre; we' got the same expansion line and same terminal, but 
 the area is minus the initial pressure, or a mean average pro- 
 sure of 10.5 lbs. instead of 15 lbs., as in the first instance, repre- 
 senting a loss of 30 per cent, in power. 
 
 Than, again, if the same pressure, viz., 80 lbs., be expanded 10 
 volumes, the loss is reduced to 16.66 per cent.; expanded 5 
 volumes, the loss is reduced to 0.76 per cent., and if only ex- 
 panded 3 volumes, the loss is reduced to about 7 per cent. 
 
 Therefore the greater the i-atio of expansion in a sin_y;lo 
 cylinder the greater the loss by clearance, and the less the ex 
 pansion in a cylinder the less the percentage of loss by clearance. 
 The loss by clearance may be .educed to u (certain extent, but 
 not entirely- overcome by coiupression or cushion. 
 
 ( 'ONDENSATION. 
 
 The loss by condensation is due to the variation in the tem- 
 |)orature of steam during expansion. If steam at 80 lbs. gauge 
 pressure, or 95 abs dute, be expanded 20 volumes, tho initial tem- 
 perature would bo 324 degrees Fahrenhiet and the terminal 
 about 160 degrees. 
 
 During expansion, as the temperature of tlie steam falls, the 
 temperature of the metal of the cylinder tails in proportion, so 
 that when the boiler pressure is again admitted to the cylinder it 
 takes a certain proportion of the steam admitted to raise the 
 temperature of the suri'ounding metal to the initial temperature; 
 the greater the ratio of expansicm the greatei- the variation in 
 temperature in the I'yiinder, and the greate" the proportion of 
 
 4 
 
20 
 
 10 
 
 6 
 
 8 
 
 8tf«m required to raiHe that temperature; the Ibhb the expansion 
 in a cylinder tfjii Jesn tlie variation of temperature, and the Ip-w 
 Hteani will be condenned in raining tiiat ten.perature each Btroke ; 
 or the smaller the volume of^team admitted to the cylinder each 
 stroke the greater will the percentage "of loss by condensation " 
 bear to that volume, and, on the other hand, the greater the 
 volume of steam admitted to the cylinder each stroke the Ibbh 
 will the percentage "of loss by condensation" bear to that volume. 
 From experiments carried out these losses have been com- 
 puted approximately for unjiicketed single cylinder engines with 
 low percentage of cleariince as follows, viz. :— 
 
 Expunsiono. I'owor Loss. 
 
 56 p. f. 45 p. c. 
 
 «5 " 35 '• 
 
 7B " 26 " 
 
 80 " 20 " 
 
 2 85 " 15 " 
 
 With 5 per cent, added for condensing engines, 
 Another seiious objection to high ratios of expansion in a 
 single cylinder, is the very great variation in the working strains 
 throughout the stroke. For example, if wo expand 80 lbs. steam 
 pressure to 20 volumes in a single cylinder Condensing Engine, 
 we have a pressure of 92 ILs. por ^q^urc inch of piston at the 
 beginning of the stroke, 1 .75 lb. at the ..nd of the stroke, and a 
 M. E. P. ot 15 Ibn., and us the strength of un engine in all its 
 woiking parts must bo in proportion to the greatest pressure to 
 which it is subjected, then the weight of the working parts must 
 be entirely out of proportion to the power actually developed, and 
 the t\y wheel especially must be very much heavier than that re- 
 quired in an engine whoi'e steam is expanded from ,! to 5 volumes. 
 The theoretical gain by expansion in a condensing engine is 
 approximately as follows, taking 80 lbs. gauge pressui'e without 
 expansion as a basis. 
 
 Expanded to 20 volumes. To por cent. 
 10 - ti5 
 " 6 " (10 " 
 
 " 'a " 50 ■' 
 
 " 2 " 40 " 
 
 " Ik " -'() 
 
 To obtain the economical advantages resulting from high ratios 
 of expansion, and Mt the same time avoid the enormous losses 
 attending its expu,.. ion in a single cylinder, is the object oi the 
 introduction of the compound. Triple and (iuadruple'expansion 
 engines. For example, in a compound engine with low pressure 
 cylinder four time, the area of high pressure, l(i expansions may 
 be .,blaiiie.l with four expansions in each cylinder. In this way 
 the high pressure cylinder works with steam between limit« of 
 tempeiature, such as occasion compaiatively small lo.sses by con- 
 densation, and the low pressure cylinder works between the 
 temperature of the exhaust from high pressure and that of the 
 c.iidenser; these temperatures not varying very widely the loss 
 by c..nden.sati(m is correspondingly small. Another great ad van- 
 tage of the compound over that of the single cylindiii- engine 
 (expanding steam to the same number of volumes), is the botte,. 
 distribution of the work throughout the stroke, admitting of the 
 working parts being made much lighter in proportion to the 
 actual power develojjed. 
 
 Ii would almost apjjear as if the economical limit in expansion 
 had been reached, as by our example for the last period, the 
 theoretic consumption lor 150 lbs. expanded 20 volumes, was 10 
 lbs. of water per hour per II. P., whereas, if we raise the pre-sure 
 to 200 lbs. and expand :i0 volumes, the gain is only abtit 5 
 per cent. ; if raised to 400 lbs. and expanded 40 volumes, the gain 
 IS about 20 percent.; and if to 800 lbs. expanded 40 volumes 
 about 25 per cent. ' 
 
 But to counteract this apparent gain, we have increased coal 
 consumption in raising the water to the temperature duo to the 
 increase of pressure, and also increased losses by condensation in 
 using steam ut that temperature. 
 
 5