vapour

sation of the steam; and if it had, he was not the first who combined and its condenin the same machine the elastic force of the sibility; for Hero's apparatus does the same thing. We proceed to the year 1699, when Mr. Savery exhibited to the Royal Society a model of the first engine, which is known to have been realized on the large scale. This model and its mode of action will be rendered intelligible by the diagram, Fig. 11, where a is a boiler communicating by the bent pipes b and c with the cold vessels

Fig. 11.

God

d and e: ƒ and g are the pipes through which the water is forced out of the vessels by the steam, and h, k, are the pipes by which it enters these vessels from the well or cistern beneath. The arrangement of valves is precisely like that supposed in the Marquis of Worcester's, Fig. 7, and the only difference is, that here the cold water ascends into the vessels d, e, instead of flowing from the same level, and that the cooling of the vessels d, e, is hastened by suffering cold water to run upon them alternately from the cocks I, m. contrivance, the artificial condensation, is the only point of complete novelty about Savery's machine. He has, however, the rare merit of combining several principles which had been merely suggested, in an apparatus which presented to the world, for the first time, an effectual working machine for raising water by fire.

But we must now hear M. Arago.

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This last

His section headed "Savery," thus begins: "We have no proof that Salomon de Caus ever constructed his steam engine;" I might say as much of the Marquis of Worcester. That machine of Papin, in which the action of the vapour and its condensation are successively employed, was executed only on a small scale. The reader will form an exact idea of Savery's, if he recollects that of Salomon de Caus, and attends to the following considerations."

Thus the only description which M. Arago gives of the first work

ing steam engine mankind ever saw, is by stating verbally, without any diagram, where it resembles and where it differs from what he calls the steam engine of Salomon de Caus. It will now be seen why M. Arago elongated the jet and valve of de Caus's diagram into indefinitely extended pipes; evidently for the purpose of assimilating them to the pipes f, g, h, and k, of Savery's engine.

In the year 1705, a patent was granted to Newcomen, Cawley, and Savery, for a steam engine, which was invented by the two former, and which was the first that ever became extensively useful; for Savery's was limited to inconsiderable heights, unless the vessels were subjected to dangerous pressures, and it was, moreover, very expensive in its consumption of coal.

The machine of Newcomen and Cawley, which is still partially Fig. 12.

d

used where coals are cheap, consists of a boiler, a, from the upper part of which a pipe enters the bottom of the cylinder, b, in which works the piston, c, attached to the chain, d, whose upper end is fixed to one extremity of the beam, e, e. From the other end of the beam hangs the chain, f, supporting the pump rod, g. A communication is opened between the boiler and the cylinder by moving a valve; the steam enters the cylinder, and the piston is raised by the weight of the pump rods. When the piston is at the top of the cylinder, the communication between the boiler and cylinder is closed, cold water is then suffered to flow through the pipe, h, into an outer cylinder, or case, k, k, which surrounds the cylinder, b. The space

between the two is then filled with cold water, which rapidly condenses the steam under the piston, produces a partial vacuum, and causes the descent of the piston with a quantity of power proportioned to its area, the weight of the atmosphere, and the perfection of the vacuum.

This engine, after it had been so far completed as above described, cost the patentees seven years' labour and experience before it became an economical machine for draining. Notwithstanding that, according to M. Arago, a "proper machine for draining" had been in existence ever since the work of Salomon de Caus, in 1615; and notwithstanding that Papin had, in 1690, published (he says) "the most clear and methodical description of the engine known at present by the name of the Atmospheric Steam Engine."

The engine of Newcomen, which M. Arago admits to be the first that rendered any considerable services to industry, he describes as he does Savery's, without a diagram. He says, that "excepting some very essential details, it is nothing but the machine proposed in 1690 and 1695, by Papin." Excepting some very essential details, it is merely the machine of Hero. M. Arago never gives the slightest hint that he has put Newcomen's valve and boiler to Guericke's cylinder, and ascribed the combination to Papin; he says, that both Papin and Newcomen produced the condensation by cold, though the English mechanic adopted a better plan of cooling for a working machine than that which had been employed by Papin in his model," and he proceeds, "The machine of Papin thus modified as to the manner of cooling the aqueous vapour, excited to the highest point the attention of the proprietors of mines."

In this last paragraph there is not merely a continued suppression of the fact, that the apparatus described as Papin's is not Papin's, but Newcomen's; there is a direct assertion that the two machines differed only as to the manner of cooling the vapour.

The "modification" which M. Arago thus misrepresents as to its extent, and which he accounts of so little consequence, made all the difference between exciting the attention of proprietors of mines, and exciting no attention at all. Papin's steam cylinder lay unnoticed and undisturbed, and apparently forgotten, not only by the world, but by Papin himself; for no sooner had Savery succeeded in perfecting and realizing his machine, than Papin abandons his cylinder, seizes upon Savery's engine, mutilates it, and publishes it in 1707 as his own.

Fig. 13 describes this last and most palpable plagiarism, which Papin tells the Royal Society will so much increase the power of mankind, that he fears he shall be considered chimerical; he says further that it is much superior to the apparatus he had published some years before, and that he invented it without being aware of Savery's invention, which was (he says) not communicated to him till the year 1705. Papin omits the best part of Savery's apparatus, namely, the ascending pipes from the reservoir to the cold water vessels, and he claims this as an improvement. Thus he throws

aside the only part of the contrivance which modern engineers have been able to use with any regard to economy.

The boiler, a, communicates with the cylinder, b, b, and the steam forces the water up the pipe, c, into the vessel, d, whence it escapes at e. The supply of cold water to be raised takes place at f. There is evidently not the slightest novelty in this machine so far; it is much beneath Savery's in every respect. It has, however, one novelty, from which a tolerably fair estimate of Papin's mechanical talents may be formed. The water in the cylinder, b, b, instead of being exposed to the steam, as in Savery's engine, is covered by a floating hollow piston of iron, g, g, supporting an iron heater, h, which is put in and taken out like the heater of a tea-urn. No two contrivances more absurd and wasteful than these were ever devised. The professed object of the hollow iron floater was to prevent the condensation of steam on the surface of the cold water. But even a hollow iron floater is a better conductor of heat than water, when the heat has to descend, and, therefore, the appendage is worse than useless. The iron heater to be put in and out at intervals is almost too ridiculous to notice, because, at the best, a certain quantity of heat applied in that manner could produce no greater effect than the same additional quantity applied to the boiler; while it is evident that the trouble of opening the cylinder, and exchanging the cold for the hot iron, together with the loss of heat in passing through the air, would more than destroy all that was gained. The whole contrivance is puerile in the extreme, and it is the work of Papin, of whom M. Arago says, the man of genius is always misunderstood when he advances before his age."

The reader is now in possession of the stolen and disfigured child for which Papin deserted his former doubtful offspring, the clear and methodical description of the Atmospheric Steam Engine;" and

it will now be easy to estimate the respective claims of Egypt, Italy, France, and England, up to the year 1707.

But in fact the steam engine was hardly yet invented. Newcomen's machine, though infinitely superior to every former contrivance, is a crude, imperfect, wasteful apparatus, in comparison with those which the following century brought forth. The engine up to this time is scarcely worth a dispute, even if it had been produced wholly by one man; but it is obviously the result of a succession of improvements so inconsiderable, that the whole of them do not exhibit a tenth part of the scientific and inventive resources which are displayed in the ameliorations effected by Watt alone. From the year 1705, the steam engine is confessedly a British invention. For all that is refined and economical in the development and application of the heat; for all that is ingenious in the machinery; for all that is vast in the power produced, and extensive in the purposes to which that power may be made subservient, it is notorious that the world is indebted to Great Britain. If, then, De Caus and Papin had done all that M. Arago so incorrectly ascribes to them, the great question would not be affected by it.

The reader who wishes to verify the statements here given, is referred to the "Acta Eruditorum Lipsia," from 1685 to 1700; to the Philosophical Transactions" for the same period; to Papin's work, printed in 1695, at Cassel, and entitled "Recueil de diverses Pieces touchant quelques nouvelles Machines;" to Belidor's "Architecture Hydraulique" in 1725; to "Les Raisons des Forces Mouvantes," by Salomon de Caus, of which an edition, printed in 1624, is in the British Museum; to the various editions of Hero's "Spiritalia," and especially to the translation in 1606, by Porta, entitled, “I tre Libri Spiritalia," of which a copy is in the British Museum.

If any objection be made to the language here employed, in regard to a person entitled to so much respect as M. Arago, it must be recollected that the paper of that gentleman is an indiscriminating attack on the motives of several of the most distinguished individuals of the United Kingdom, not all of whom have given as much cause for suspicion as any one of the misquotations in the paper of M. Arago.

In page 176 of that paper, M. Arago says, "the greater part of the English authors," among whom he includes by name Dr. Robison and Dr. Lardner, "obstinately persist in quoting only one work of Papin, that of 1707, and refuse to take any notice of the more voluminous work of 1695."

The persons thus accused have at least the same excuse which M. Arago requires for neglecting Baptista Porta, with this additional circumstance in their favour, that they quote Papin's latest, and, according to his own account, his best contrivance, and that what they do quote, they quote faithfully. They might well be forgiven for not supposing that the promulgator of the wretched apparatus of 1707 had invented the atmospheric engine in 1695; and it might have been expected that a paper making such grave charges should VOL. IV.-No. 6.-DECEMBER, 1829.

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