was exhausted; are all so many distinct steps towards the formation of the atmospheric steam-engine of last century: which, under the hand of Watt, cast off altogether its dependence on the atmosphere, and for the first time became in every sense a true steam-engine; deriving its vacuum from the condensation of steam on one side of the piston, and its power from the impulse of steam on the other, and vice versa, according as the stroke made is downwards, and upwards, in uninterrupted succession.

CHAPTER XI.

DENYS PAPIN— HIS MEMOIR OF 1690

ATTEMPT TO FORM A VACUUM

BY GUNPOWDER - HIS SUBSEQUENT ADOPTION OF SAVERY'S PRINCIPLE

HIS DIGESTER MISTAKES OF ENGLISH AND OF FRENCH WRITERS IN REGARD TO HIS INVENTIONS-TRANSLATION OF HIS PAPER OF 1690.

WE come now to the Memoir in which Denys, or Dionysius Papin, in the year 1690, availing himself of the apparatus of Guericke, and of the true ideas as to a vacuum and the pressure of the atmosphere, of which we have just been speaking, set forth another important fact which he had observed. This was, that if a close cylinder were filled with steam, and the steam were then allowed to condense, a vacuum would be formed within the cylinder; and that, consequently, a moveable piston, fitted to the interior of the cylinder, would then fall, under the pressure of the atmosphere; just as it did in Otto Guericke's experiment, where the vacuum had been formed by the air-pump.

Papin mentions, in the outset of his Memoir, that he had applied steam to that purpose, in consequence of the failure of a previous attempt he had made to obtain a vacuum by the explosion of gunpowder, in the same cylinder, beneath the piston; the explosion always leaving the vacuum imperfect, on account, as he supposed, of a portion of the air which remained, or, as we should now say, of the gases which were the products of the combustion. But he proposed to carry out his ingenious idea of forming the vacuum by condensation, by the clumsy, tedious, and unprofitable expedient of removing the fire from beneath the cylinder, previous to each stroke or descent of the piston; a method which even the greatest of his admirers among his own countrymen admits was "scarcely tolerable even in an experiment in"tended to verify the accuracy of a principle;" and which

involved so great an expense of time, fuel, and labour, as to make it confessedly of no use in practice.

To practice, accordingly, Papin seems never to have attempted to apply it, notwithstanding the suggestions to that effect contained in his Memoir; and we also find that on the appearance of a better invention for condensing the steam, eight years afterwards, Papin abandoned his own scheme, and betook himself to the construction of an engine, (which, however, turned out not to be a good one), in which he made use of the new plan. As for the applications of a moving-power which he enumerates, and which, if original, would have been ingenious enough, he may have found them, and many more, ready stated to his hand in a book published in London in 1651, entitled, 'Invention of Engines of Motion lately brought to perfection; whereby may be despatched any work now done in England, or elsewhere, (especially works that require strength and swiftness), either by wind, water, cattel, or men, and that with better ' accommodation and more profit than by any thing hitherto known and used.' This is in the form of a letter to Hartlib, author of a celebrated Discourse on Flanders Husbandry, and many other agricultural works. The unknown author of the Engines of Motion' says, "I have already erected one "little engine, or great model, at Lambeth." See Stuart's 'Anecdotes of Steam-Engines,' pp. 77-79, where it is suggested that the author may have been the Marquis of Worcester.

The best methods of applying the power to those various mechanical processes, which both Papin and his great advocate M. Arago have treated as difficulties of a very secondary kind, have in reality proved far otherwise; they have exercised the ingenuity of the most eminent engineers for upwards of a century and a half; and without their solution no mechanical power, however great, could be deemed of very much use to the world. The perfection in all kinds of mechanism of which our country now can boast, has not been attained without incessant and most praiseworthy exertion; and it is melancholy to consider how many persons, respectable alike for their talents and character, have

sunk under the difficulty of contriving those practical applications which M. Arago, himself always most honourably distinguished in theoretical research, considered as having been made with so much facility. For, alas! "persons

"whose whole life has been devoted to speculative labours, "are not aware how great is the distance between a scheme, apparently the best concerted, and its realisation.”

66

There is no doubt that Papin, who was at one time Secretary to the Royal Society of London, was long best known in England by his Digester, described by him in the work mentioned below; which was published in this country, while most of his other writings, all of them now more or less scarce, were either published abroad, or preserved in the form of memoirs in the Transactions of learned societies. They are therefore inaccessible to most readers, and cannot be continuously examined by any one without very considerable difficulty. The Memoir of 1690, now so much referred to, long lay entombed in the bulky series of the 'Acta Erudi'torum Lipsia,' and in a small work, a collection of nine of Papin's short treatises, which, although printed in two forms, viz. in Latin at Marburg, and in French at Cassel, both in 1695, is of such singular rarity, that it is even doubtful whether more than a single copy of it can now be affirmed to be in existence.†

It is from these circumstances alone, we firmly believe, and not from any undue national partiality, that the real claims of Papin to some of his ingenious ideas have been so long overlooked; and, from the same cause, we now quite as commonly meet with over-estimates of the degree of credit which really attaches to his experiments, unavailing in practice as many of them may have proved to be.

66

6

Not only some English writers, (as has sometimes been erroneously supposed), but some of the principal French authors also, have betrayed an entire want of acquaintance with Papin's Memoir of 1690, and with the ideas suggested in it; and have grounded their estimate of his merit as an inventor either on his well-known Digester,' or on the inferior sort of steam-engine which he described in 1707, or on both of those machines, but on nothing else of a more recondite or remarkable nature. Thus Belidor, in his great and valuable work published in 1739, says, "To say a word "on the origin of the machines moved by the action of fire. "I have not found any one who earlier seized the idea than "M. Papin, Doctor of Medicine, Professor of Mathematics at Marburg, and Fellow of the Royal Society of London, in "the preface to a little work entitled, Nouvelle manière "d'élever l'eau par la force du feu,' printed at Cassel in "1707,"* &c. M. De Prony, in 1790, after referring to the same work of Papin, says: "We shall not speak of Papin's "machine, which is more imperfect than that of Savery; the great celebrity of his experiments on steam chiefly rests on "the use which he has made of it to dissolve bones by means "of his Digester, well known under the name of marmite de Papin,"† &c. &c. And Bossut, in 1796, has followed a similar course; speaking first of the "marmite de Papin," as described in his work of 1682, and then of the publication which appeared, at Cassel, in 1707. While in England, on the other hand, Stuart and Farey, in 1824 and 1827, (not to name other writers), have both done ample justice to all the contrivances of M. Papin that could be cited in connection with the history of the steam-engine.

66

66

Dr. Ducoux, a physician at Blois, who some years ago published a pamphlet on the life and works of Papin,§ dwells on the contents of the latter with what we cannot but term