IS39.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



405 



of the atmosjilieie above; as in the bpginninf;, the counterpoise brings 

 up the piston to the top of the cylinder, and all parts of the apparatus 

 ai'e restored to their original condition. A second evacuation, or rather 

 if you prefer it, a second annihilation of the interior air will again briirg 

 down the piston, and so on as before.* 



The true motor of the system would in this case be the weight of the 

 atmosphere, and let us undeceive those who might imagine, that because 

 they can walk and everr run through the air with ease, that it possesses 

 neither power, or weight. With a cylinder, two metres (78 inches) in 

 diameter, the effort which the pistoir of the engine woirld make in des- 

 cending, the weight which it could lift the whole height of the cylinder 

 would be 31,000 kilogr-ammes (G9,-2S1 lbs.) This enormous power, fre- 

 quently renewed, would be obtained by means of a very simple machine, 

 if we discover a prompt and economical method of engendering and de- 

 stroying at pleasirre arr atmospheric prcss\tre in a metal cylinder. 



This problem Papin solved — his line, his great solution, consisted of 

 the substitutioir of an atmosphere of steam, for an atmospher'e of com- 

 mon air, if replacing this by a gas which at 100>' centigrade t2I2uF) has 

 precisely the same elastic power, but \\ith an important advantage which 

 the ordinary almospher-ic does not possess, that of the power of the 

 aqueous gas weakening itself very quickly when the temperature is 

 lowered, so that iir the end it disappears almost entirely, if the refrigera- 

 tion be sufficient. I should characterize the discovery of Papin, as well, 

 and in fewer words, if 1 should say, that he proposed to make use of steam 

 to create a vacuum in large spaces, and that this method is prompt 

 and economic, t 



The machine in which our illustrious fellow countryman was the first 

 to combine iir this manner the elastic power of steam, with the property 

 which steam possesses of beirrg anrrihilated by refrigeiation, he rrever 

 executed on a large scale ; his experiments were confined to mere 

 models. The water intended to engender the steam, did not everr occupy 

 a separate boiler, but inclosed in the cylinder, it rested on a metallic 

 plate, which closed it at boltom. It was this jilate which Paprrr Ireated 

 directly to convert the water iirto steam, and it was frorrr this same plate 

 that he removed the fire when he wished lo effect the condensation. A 

 similar process,' har'dly endurable in arr experiment intended to verify the 

 correctness of a priirciple, would evidently be irradmissible if it were re- 

 quisite to make the piston move with rapidity. Papin, while he said 

 " that this could be effected by differerrt constructions easily to be ima- 

 gined," did not point out any of thee modes of operation He left to 

 iris sirccessors both the nrerit of the application of this fruitful idea, arrd 

 that of the inventions in detail, which alone can secure the success of a 

 machine. 



In the first part of our investigation on the employment of steam, we 

 quoted the ancient philosophers of Greece and Rome ; one of the most 

 celebrated mechanics of the school of Alexarrdria; a pope ; a gerrtlerrrarr 

 of the court of Herrry the Fourth ; an hydraulist, born in Normarrdy, 

 that fertile birth-place of great nrerr, which has contributed tojthe national 

 pleiad, Malherbe, Corneilie, Prussin, Fontenelle, La Place, and Fresnel; 

 a member of the Huuse of LorJs, arr Errglish mechanic; and lastly a 



* PAPIN'S MACHINE. 

 Consisted of a boiler B, provided with a safety valve V ; and a cylinder 

 G H, connected to the boiler by a steam pipe S. The cvliuder was closed at 

 the toi>, and contained a floating piston P ; and the base of the cyliniler ter- 

 minated in a curved tube T, -which ascended into a cylinder M • the bent 

 tube had a pipe Y, from a reser-voir of water communicating with it and it 

 was provided with a valve at r. Now suppose the cylinder G H, to be tilled 

 with cold water by the pipe Y, from the reservoir, and the boiler to con- 

 tain sti-ong steam ; by opening the cock E, the steam would be admitted 

 and, pressing on the Boating piston P, cause the water to ascend into tlie' 

 cylinder M ; its return is prevented by the valve K, and the steam cock E 

 being shut, and the cock R opened, to let the condensed steam escape at the 

 pipe R, the water from the reservoir refills the steam cylinder through the 

 pipe Y, and it is ready for repeating the operation. The water raised to be 

 directed to any useful object by the pipe D. — Tredgold, 



t An English nieclianist, doiibllf?«ly deceived by an imraithrnl translation, asserted 

 some lime ago, lliat llie idea of emplojing steam in tlie same macliine as an elastic 

 power, and as a rapid means of engendering a vacuitm, bejonged to Hero On mv 

 side I have proved incnntestably tliat the mechani»t of Alexandria never thonght of 

 steam; that in his apparatns Ilie alternate movement was only lo be prodnced by llie 

 dilatation and condensation of the air, arising from Ihe inlenniiling action of the 

 tilsr TASK— Note of U. Arago. 



French physician of the Royal Society of London, for we are obliged to 

 confess, that Papin almost always exiled, was only a corresponding 

 Member of our Academy. Now is the time for simple mechanics and 

 workmen to enter on the scene, in which it will be found that all classes 

 of society have united for the formation of a machine, of which the whole 

 world is to errjoy the benefit. 



In 1705, fifteen yeais after the publication of the first memoir of 

 Papin, at Leipsic, Newcomen and Cawley, the first, a hardwareman ; the 

 other a glazier, at Dartmouth, in Devonshire, constructed, (recollect that 

 I do not say projected, for the distinction is important)* a machine 

 intended for diaining, and in which there was a separate boiler in which 

 the steam or-iginated. This machine, as well as Papin's little model, 

 consists of a vertical metal cylinder, closed at the bottom and open at 

 top, and a piston, well fitted, intended to traverse it in its whole length in 

 ascerrding and descendiirg. In both, wherr the steam arrives fi'eely at 

 the bottom of the cylinder, fills it, and thus counterbalances the pressure 

 of the external atmosphere, the ascending movement of the piston is 

 effected by means of a counterpoise, t Iir the English nrachine, indeed, 

 in imitation of that of Papin, as soon as the piston has arrived at the 

 termirration of its ascerrding course, the steam which had contributed to 

 raise it, is refrigerated. A vacuum is thus made in the whole capacity 



• M. Arago. still acting upon the old system, :igain commences a system of trickery, 

 which is fortunately too ci>bwebby for any audience but one, to the prejudices of which 

 it was addres-ed. 'I'o any other it would have needed an explanation how his country 

 glazier found means to benefit by Papiu's projection at Leipsic— A'o/e of the trans- 

 lator. 



t NEWCOMEN'S STEAM ENGINE. 



The following is a description of the engine, as far as it was improved by 

 Newcomen. B represents the boiler with its furnace for producing steam ■ 

 and at a small height above the boiler is a steam cylinder, C, of metal, bored 

 to a regular diameter, and closed at the bottom, the top remaining open. A 

 communication is formed between the boiler and the bottom of the cylinder, 

 by means of a short steam pipe, S. The lower aperture of this pipe is shut 

 by the plate ;j, which is ground flat, so as to apply very accurately to the 

 whole circumference of the orifice. This plate is called the regulator, or 

 steam cock, and it turns horizontally on an axis «, which passes through the 

 top of the boiler, and is fitted steam-tight ; and has a handle to open and 

 shut it, 



A piston P is fitted to the cylinder, and rendered air-tight by a packing, 

 round its edge, of soft rope, well tilled with tallow to reduce the friction, and 

 its upper surface is kept covered with water to render it steam-tight. The 

 piston is connected to a rod, P A, which is suspended by a drain from the 

 upper extremity D of the arched head of the lever, or working beam, which 

 turns on the gudgeon G. This beam has a similar arched head E F, at its 

 other end, for the pump rod H, which receives the water from the mine. The 

 end of the beam to which the pump rod is attached, is made to exceed the 

 weight and friction of the piston in the steam cylinder; and when the water 

 is drawn from each a depth, that the steam piston is too heavy for this pur- 

 pose, counterpoise weights must he added at I, till the piston will rise in 

 the steam cylinder at the proper speed. At some height above the top of 

 the cylinder is a cistern L, called the injection cistern, supplied with water 

 from the forcing pump R. From this descends the injection pipe M, which 

 enters the cylinder through its bottom, and terminates in one or more small 

 holes at N. This pipe has at O a cock, called the injection cock, fitted with 

 a handle. At the opposite side of the cylinder, a little above its bottom, 

 there is a lateral pipe, turning upwards at the extremity, and provided with 

 a valve at V, called the snifting valve, which has a little dish round it to 

 hold water for keeping it air-tight. 



