In the description given by him, he proposes to withdraw the fire from the apparatus, after it had generated the steam therein, in order that the air shall cool the cylinder, and condense the steam. Here then was Papin hovering upon the threshold of a mighty discovery, and forsaking it as soon as reached kine as we may now consider this idea to be, from its close approach to the principle of action in the steam-engine, we cannot justly esteem it as more than the transient opinion of a talented man, launched, probably, as a " riddle " for others to solve. Frustrated in his prior attempts to execute the projects of his mind, throughout a long career of experimenting, he seems to have hesitated on the very verge of success; this, surely, he had never done, if he could have persuaded himself that the belief he then put forth in the possible contrivance of a machine on this principle, were well-grounded. Mere visionary scheming is a very different affair from that of effectuating a well conceived design; and this undigested thought detracts nothing from the merit due to Savery for having likewise conceived it, and given to the world evidence of its value, by its practical adaptation. Pepin narrowly escaped the accomplishment of a great discovery, and nothing more ; and in saying this, let it not be supposed that we estimate lightly the great talents he unquestionably displayed ; he was a man of high celebrity, and much estimated by his learned contemporaries. Through Leibnitz he, at a subsequent period, became apprised of Savery's success. That cele brated person, on his return to Germany, forwarded to him a copy of the Miner's Friend, and desired to have Papin's opinion on its merit. Then it was that Denys became incited to recur to his former notion ; acting under the patronage and with the assistance of the Landgrave of Hesse, he subsequently, in 1707, produced the engine known by Papin's name. From the following description and figure, it will be seen to differ most essentially from Savery's, to which, after all, it is far inferior, as well in contrivance as in power.
The boiler a has a pipe b, closed by a lever valve, through which k is sup plied with water ; the pipe d connects it with the forcing vessel/ is is an iron cylinder, lying in a cavity made in a hollow floater, and which may be inserted through the orifice g, made in the top of the forcing vessel, and closed by a valve which is kept in its position by a weight hung on the end of the lever. s, a funnel, through which water is introduced, and closed by a cock h; the pipe k is a continuation of the forcing vessel f, and is inserted in the reservoir and air vessel tn. o, a pipe conducting the water which has been forced into the air vessel, to its destination.
The steam from the boiler a, flowing through thepipe d, presses the floating piston downwards, and the water beneath iris thus forced up the k into the forcing vessel m; when the floating piston nas reached the limit of its MOO*. men; the cock tl is turned, to shut off the further flow of steam into the forcing vessel, and the vapour is allowed to escape from f, by the cock e; at the same moment the valve h is turned, which allows the water in the feeder a to flow into f, and raise up the piston, the water in k being prevented from descend ing, by the Valve placed near its bottom. The opening in the lid of the forcing vessel, closed by the lever valve g, is for the purpose of allowing a red hot iron cylinder to be inserted, in order to increase the heat of the steam ; by the water being forced into the receiving vessel ni, the air which it contains is compressed ; and this is to give a greater velocity to the issuing water.
It has been deemed necessary to enter into these particulars, oecause the French authors before alluded to, who have treated of the Steam-Engine, ascribe to Papin and Amontons (his contemporary,) the credit which appears really due to Savery ; of whom they speak as a person who merely carried into execution the ideas originated by their own countrymen. The preceding description of
his engine will serve to show the real relation which the one engineer bears to the other. To Papin belongs the sole and unqualified merit of inventing the safely valve, without which the steam engine had been a frightful and unmanage able power ; and this alone is a distinction sufficient to secure to his memory respectful and honourable mention, in every work that treats of the history now under consideration.
With respect to M. AXONTONS, there needs be no more said than that the con trivance of this eminent man, known by the name of Amontons' " Fire-wheel," was confined to the production of circular motion, by meant of the alternate -dilatation and contraction of air, and not of the steam of boiling water ; so that, excepting the primary cause of that motion—fire---it has no connexion what ever with the subject of steam ; and, ingenious as his device undoubtedly is, it warrants, in reality, no farther allusion in this place. No working model ap pears to have been made of it, and the computations of its power made by the inventor are merely assumptive. The weight of M. Amontons' name, therefore, adds but little to the evidence brought forward by such authorities, to establish the claim of the French nation to the honour it seeks, in this respect.
Whilst these modifications and improvements of Savery's engine were en_ gaging the attention of skilful mechanics, TROMAS NEWCOMEN, ironmonger, and JOHN CAWLEY, glazier, of Dartmouth, Devon, Baptists, werJ employing them selves together in a series of experiments upon the power of steam. Newcomen is represented to have been an acute and sensible man, of great inventive skill, but possessed of little scientific knowledge. We sometimes find him called a " blacksmith ;" but perhaps the term did not at that period imply the same com paratively humble calling as it mostly does at this; for Dr. Allen makes men tion of " his very good friend, the ever-memorable Mr. Newcomen, whose death he much regretted ;" and from these terms it may be supposed that lie enjoyed. that rank in society, and the regard of men of eminence, beyond the mere toleration of patronage,) to which his talents entitled him : the place and time either of his birth or death are alike unknown. It is not stated RR what degree his associate Cawley shared in the merits of the invention introduced in their joint names ; it would seem, however, that Newcomen, of the two, possessed the master-mind, for Desaguliers represents him as communicating his project to his friend and associate Cawley, with whom he made several experiments in the year seventeen hundred and ten. The account, as it refers'to date, is remarkable. At the time when Newcomen and Cawley were applying for a patent, Savery came forward to claim the invention as his own, on the ground that the method of procuring a vacuum by steam was his discovery ; and, probably from pru dential considerations, they were induced to make a concession, for Savery's name was included with theirs in the grant, though, as it appears in the sequel, he took no part in the progress of their labours, beyond that of participating with them in the profits derived from the invention. Now, the patent granted to them in their three names, for this very invention, bore date 1705, jive years anterior to the time Newcomen and Cawley are stated by Desaguliers to have been making "several experiments," (by which we are to infer the initiatory attempts to realize a crude notion, rather than the completion of a machine already contrived,) and two years anterior to the date of Papin's engine. And here it may be men tioned, that the French authors have also claimed this engine as the invention of their countryman Pepin ; but without any argument that calls for particular notice.