1839.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



407 



THE LIFE OF JAMES WATT fconcludetU) 



If a free eommuiUL'ation exist between a cylinder full of steam and 

 a vessel exhausted of steatn and air, part of the steam in the cylinder will 

 pass with great rapidity into the vessel, and the motion will continue 

 until the elasticity is uniform throughout. Supposing, then, that by 

 means of an abundant and continual injection of water, the vessel could 

 be kept constantly cold throughout its extent, the steam would be con- 

 densed on its arrival, all the steam with which the cylinder was originally 

 filled would be successively brought in, and the cylinder would thus be 

 relieved from the steam, without its surfaces being in the least refrige- 

 rated, and the new steam with which it might be necessary to refill it 

 would lose none of its elasticity. 



The co»A'H,v(T attracts to itself the steam of the cylinder, on the one hand, 

 because it contains cold water, and on the other, because the remainder 

 of its capacity does not contain any elastic fluid. But the moment that 

 a first condensation of steam has been effected, these two successful 

 conditions disappear ; the condensing water becomes warmed by absorb- 

 ing the latent caloric of the steam ; a considerable quantity of steam is 

 formed at the expence of this warm water, and the cold water contained 

 atmospheric air, which has been liberated during the elevating of the 

 temperature. If after each operation, this hot water were nut taken 

 away, together with the steam and air which the condenser contains, it 

 would in the end produce no result. Watt, effected this triple evacuation 

 by means of an ordinary air pump, of which the piston is carrried by a rod 

 attached lo the beam and sel in motion by the engine. The power employed 

 in keeping the air pump in motion diminishes by so much, the power of the 

 machine, but this is nothing in comparison with the loss which ensued 

 in the i Id process, by the condensation of the steam on the cold surfaces of 

 the body uf the cylinder — scefg. 9. 



One word more, and the advantages of another invention of Watt's will 

 be apparent to every body. When the piston descends in Newcomen's 

 engine, it is the atmosphere which impels it ; this atmosphere is cold, 



LEUPOLD'S ENGINE. 



M. Arago has omitted to notice the contrivance of Leupold, which we shall 

 tere g>ve, ,n order that this ingenious inventormay not be passed over unnoticed. 



Leupold was a native of Saxony ; in 1723 he commenced publishing a large 

 oollec ion of machines, which extended to several folio volumes ; amon..- other 

 inventions, he suggested the high presmre engine, a,id fuur-way cock, a view is 

 ulTnT,^- ^- 0^"/,>'"'" B' ^' Pl--d two cylinder's C C, iftted ^ith stelm! 

 cvuSerT!:,^'''; l?""™fT ^'^f™-™':'^' », is placed between the boiler and 

 cylinders, so as to alternately admit steam into one cylinder, and let it out 



brw1;'i°st"-d'^'^aS"'°°' '^*^ admission of strong steam'from the' boile 

 a nluno'.r nf ' '^''P'^'ff^ "'<' »'hcr end of a lever connected to the rod of 

 .!,„ .u^ . a I"""?' ^y;^'":^ "pauses the water to rise through the pipe, and bv 

 water r;ateT'°Th"' 'X" f 'f " i" "'^- '"° ^>"°''"^ => continulf st'rcam o"^ 

 nressu P ZfJ^' 2 . " '"'^^- ""'"^^ "^ '^^ principle of employing high 



pressuie steam under a piston was given. f j b "^b" 



Fig. 7 and 8. 



Fig. 7 and 8, show an enlarged view of the four. 

 "•".V^ock. T is a passage to the top of the cylinder 

 and B that to the bottom S the passage for the^steam; 

 ana L the passage to the condenser. Fig. 7, shows 

 the passage rom S to T, open for the stelm o pT^ 

 from the boiler to. the top of the cylinder, and the 

 passase from B to C open to allow the escape of he 

 steam Irom below the piston to the condenier, when 

 the diagonal ,s turned across to the opposite dii^ction, 

 he passages are then reversed, the steam from the 

 boiler will then pass to the bottom of the cvlinder bv 

 the passage from S to B, and the steam above the 

 piston will escape through the passage T and C to the 

 condenser. The other figure shows^in what manner 

 the steam may be shut off at any period of the stroke. 



and must consequently cool down the surfaces of the metallic cylinder, 

 o])en at the top, which the cold air successively covers throughout.* This 

 cooling down is only overcome dming the ascending course of the piston, 

 at the expense of a certain quantity of steam. No loss of this kind, how- 

 ever, exists in the iin])roved engines of Watt; the atmospheric action 

 IS totally shut out in the following way. The cylinder is closed at top 

 by a metal covering, perforated only in its centre by an opening pro- 

 vided with close stuffing, through which the piston rod moves freely, 

 without allowing a passage either for the air or the steam. The piston 

 thus divides the cylinder into two distinct and closed portions ; when it 

 descends, the steam of the boiler passes freely in the upper portion by a 

 pipe properly placed, and forces it down in the same way as was done 

 by the steam in Newcomen's engine. This motion is executed with- 

 out any hinderance, the bottom of the cylinder only being in communi- 

 cation with the condenser, in which all the inferior steam is turned into 

 water. From the moment that the jiiston has gone down, it is only re- 

 quired to turn a cock to open a communication between the two parts 

 of the cylinder situated above and below the piston ; when both parts 

 are filled with steam of the same degree of elasticity, the piston is 

 then in a state of equilibrium, and is raised to the top of the cylinder, as 

 in the atmospheric engine of Newcoraen, by the mere action of a slight 

 counterpoise — see fig. 10. 



While following up his search into the means of saving steam. Watt 

 reduced still fiirther, almost indeed to nothing, the waste, which occurred 

 from the cooling down of the outer surface of the cylinder in which the 

 piston works. To effect this, he enclosed the metal cylinder in a larger 

 wooden cylinder, and filled with steam, the ring-like interval which 

 divided them. 



Thus was the steam-engine completed— the perfection which it de- 

 rived from the hand of Watt is evident, its immense utility admits 

 not of a doubt. You would expect therefore, that it would immediately 

 re-place, as a means of draining, the comparatively ruinous engines of New- 

 conien. Do not deceive yourselves ; the author of a discovery has 

 always to contend with those whose interests it may affect, with the 

 obstinate partisans of all that is old, with the jealous and the envious. 

 These classes combined, form, we are obliged to confess, the greater 

 part of the public, and yet in my calculation, 1 omit double cases to 

 avoid a paradoxical result. This compact mass of opponents, time alone 

 can separate and destroy ; but time is not enough, they must be attacked 

 boldly, they must be attacked without ceasing ; the means of action 

 must be varied, imitating the chemist, who, is taught by experience that 

 the entire dissolution of certain alloys requires the successive employ, 

 nient of several acids. That strength of character and persistance of 

 will, which in the long run defeat the cunningest intrigues, may not, some. 



Fig. 9. 



ATMOSPHERIC ENGINE, WITH CONDENSER. 



P ft,'!' ^' *<"'%,t° ''"^'"'' "^ ""'^ ''''"^' "'"''■'' <^ ■= a cylinder, open at the top; 

 r VA ^B "■ V"^ ',"'^™ P'""'"' ^™"" ""• '"'"" through the pipe S, and bv 

 J^l , '"°/''' '■^■■''°''." =" ^' ""'' "'^« "^-^ piston. A is a pump with a 

 solid piston, to receive the condensed steam, air, and water, .nd expel it : the 

 injection ,s made into the pipe E; and I is the injection c^ck : F is a cock to 

 To hUr ^'' ""^^ ™' "' '''°^' ""' P'^'™ p, when the engine is at rest. 



ton in b„ I ,f! rV\ ""^ '''r" """ "'■*'= ^'^^ Q ; the pistons being at the 

 »?H nJT^l ■ ^X'"»ler and pump : then shut off the steam by the slide B. 

 thp ,Vi ,1^ ?■" r • a"',','" ""sequence of the condensation produced by 

 nmlii, ;i,^^''.tf^°?>"' "■'" J""''' °" ""= 'op °f the piston and press it down, 

 ,W tZJ' t. " ''"'™,'' ""= '°'^ •■' ^•^O"''' be open, but afterwards closed ■ 

 rnnZ "^ ^'°'^^''.^' ■™'^ ""' '''"^'^ » moved to close the passage to the 



the airY^n"" ?""""/ "'=',' ^"^ ""= ^"'■™' "'' Pi^'^^ -"' "="'" «'«"d. ""d 

 nl.Prn » w^ter of Condensation will be expelled at the' valve Q. Th« 



to continue the action. The engine may be regulated by closing the valve B 

 at any period of the ascent, and the cock I at any period 'of the descent. 



2L 



