struction or application, laid claim to the exclusive merit of having invented the engine. Dr. Denys Papin, a native of Blois, a man of great ingenuity, and of considerable acquirements as a philosopher, is considered by his countrymen to be the true inventor of the Steam Engine: a claim strongly contested by some English authors of eminence who have written on the subject, but on grounds which appear to have been taken from very erroneous and prejudiced statements. It is due to Papin to state, that no one, whose labours have produced so many important results, has in his writings shewn so little of the vanity and absurd enthusiasm proverbially characteristic of an inventor.

Papin's first project*-and it is necessary to keep this in remembrance--was to procure a first power by an air-pump. This scheme he announced as a means of enabling him to transmit to considerable distances the action of a mill, by means of pipes. The cylinders of air-pumps at one extremity were made to communicate by pipes, with equal cylinders placed at the other and distant end, which

* The Acta Eruditorum of Leipsig for 1685 contain some communications by Papin. One of these is a description of a new machine to raise water, which is further noticed in the same Journal in June, and again in the August following; and in the Nouvelles de la République des Lettres, for July 1687, is a reply by Papin, to some objections raised against this apparatus by M. Nuit. He had invented the mode of dissolving bones by Steam of a very high temperature in 1681; an account of which he published in English in that year, and with some improvements in 1682 in French, under the title of "Le Manière d'emollir les Os et de faire cuire toutes sortes des Viandes en peu de tems et à peu de fraix." In this "Digester" Papin first introduced a "Safety-valve.”

by some intermediate mechanism were there connected to the piston-rods of the pumps of a mine. When the mill was put in motion, (by a fall of water, for example,) the pistons of the cylinders to which it was attached were elevated or depressed, as it might be, and the pistons at the other distant extremity of the pipe had an opposite upward or downward movement. When the pistons, for instance, attached to the mill were elevated, the others were depressed, and so on successively. This project failed even on the small scale of an experiment, from the prodigious resistance of the piston, even when one cylinder was attached to the other cylinder by a pipe of only a few inches in length, and the slowness with which the motion could be communicated. This, Papin endeavoured to obviate, by employing some other means of making a vacuum under the cylinder, than that of pumping out the air by the mill. In 1688, he described an improvement* of displacing the air in the cylinder under the piston, by exploding gunpowder: but here again it was found that the power was trifling, for without endangering his apparatus he never could make the gaseous product in the under part of his cylinder so entirely fill its capacity as to have no air under the piston. It was now pointed out to Papin, by Dr. Hooke and others, that however perfect the exhaustion might be in the first and second projects, if the pipe of communication were of any length, the compressibility of the air (keeping its friction out of the question) was so great, that unless his cylinder was enormously long, (or the stroke of his piston, as it is technically termed,) the motion of the

* "Acta Eruditorum," p. 410.

piston at the other end would be imperceptible. However, in 1690, when he published in a separate form his description of this mode of using gunpowder, the idea of transmitting motion to a great distance was perfected by his forming a vacuum not only under the piston, but in the pipe of communication. Still this scheme, although ingenious, Papin was aware was nearly impracticable, from the great difficulty of abstracting the air by the air-pump or gunpowder; and, among other auxiliary methods which he suggested for obviating this imperfection, is the one of employing steam for forming the vacuum under the piston; and also for raising that piston by its elasticity. In this paper he shews, that in a little water, changed into steam by means of fire, we can have an elastic power like air; but that it totally disappears when chilled, and changes into water; by which means he perceived, that he could contrive a machine in such a manner, that with a small fire he would be able, at a trifling expense, to have a perfect vacuum, which, he admitted, could not be obtained by gunpowder.

In a collection of letters describing some of his inventions, this machine is the subject of his fourth communication. After noticing the difficulty of making a vacuum by gunpowder-"Where there may not be the conveniency of a near river, to play the aforesaid engine," (that of 1685,) he proposes alternately "turning a small surface of water into vapour by fire, applied to the bottom of the cylinder that contains it; which vapour forces up the plug (or piston) in the cylinder to a considerable height, and which, as the vapour condenses, (as the

water cools when taken from the fire,) descends again by air's pressure, and is applied to raise water out of the mine."*

This was a happy thought: and had Papin persevered to make the experiment, he would, beyond all question, have produced the Atmospheric Engine.† And although we cannot refuse to this ingenious man the great honour due to having given the first idea of having laid the foundation of the splendid mechanism of the "Lever Engine," the merit of putting the scheme into practice is as certainly due to another. And it so happened that Papin's claim to the actual construction of a Steam Engine on another principle (and which appears to have withdrawn his attention from the prosecution of his first project) cannot in fairness be allowed to him.

"Recueil des diverses Pièces touchant quelques nouvelles Machines :" à Cassel, 1695. Extract Phil. Trans. 1697, p. 483.

"It was not until after Savery had obtained his patent, that the attention of Papin was at all directed to the means of obtaining a moving power by Steam: for all his former investigations had been confined to the nature and temperature of Steam when prevented from escaping." Millington, Epit. p. 255. Savery's patent was dated 1698! A few pages farther on, this author, however, acknowledges, "Papin was engaged in some projects for producing a moving power through the agency of atmospheric pressure, and transmitting it to great distances by pipes; though it is not evident that he had at all made up his mind as to the best means of producing the necessary vacuum; for at one time large air-pumps to be worked by a powerful mill were proposed, at another the firing of gunpowder, and lastly the production and condensation of Steam. Although all these schemes were published, it does not appear that any one took advantage of them, or constructed an engine upon such principles, till the time of Newcomen!" P. 259.

The increasing depth of our mines, and the enormous expense even of the inadequate means which were then possessed of draining them, had become a matter of concern, not only to those more immediately interested in that species of property, but to the nation. The attention of mechanics, thus keenly directed to the subject, was bent rather to devise modes of improving the machinery then in use, by diminishing its friction and in its better ar rangement, than in the production of a more efficient and economical power. The history of the mines at this period offers but a series of failures on the part of projectors, and of complaint of those proprietors, who, induced by the urgency of the want, or the cupidity of speculation, had been induced to embark in the expense of making the experiments. Every miscarriage thus added to the obstacles which at all times impede the introduction of improvement; and the abortive attempts of ignorant or designing men were urged as reasons for disregarding the inventions of more honourable and meritorious individuals.

It was at this period that Captain Savery, a seafaring gentleman, offered an engine of his invention to the notice of the Mining Adventurers; " which shewed as much ingenuity, depth of thought, and mechanical skill, as ever discovered itself in any design of this nature :"* but, from the repeated failure of other schemes, more specious, and big with pro

* Harris, in his Lexicon Technicum, art. Engine, 1704. The engraving in this dictionary is the original one which was prefixed to the" Miner's Friend," in 1702.