the pressure of the atmosphere forcing it into a vacuum formed by the condensation of steam; and, in the second, by the expansive power of steam. The steam from the detached boiler was let into a vessel called a receiver, and, having driven out the air, was condensed by the affusion of cold water, and a partial vacuum formed. A communication being then opened with a suction-pipe, twenty-four feet in height, the lower end of which was placed in a cistern or reservoir of water, that water was forced upwards, by the pressure of the atmosphere, into the receiver. When this was nearly filled, the communication with the suction-pipe was shut off, the steam was readmitted into the receiver, and by its expansive power forced the water contained in it up an ascending, or, as he called it, a force-pipe. This second operation is similar to one of those experimentally tried by Porta, and indicated by Solomon de Caus; and not only indicated, but perhaps practised, by the Marquis of Worcester. The prior operation,-that of raising the water into a vacuum formed by the condensation of steam,—we believe to have been original with Savery. For, although Porta, or, at least, Papin,—had described the principle, they applied it in a different manner; and there is no proof, or even surmise, of that having been known to Savery when he invented his engine in 1696, or perhaps sooner. Indeed, Papin, with praiseworthy candour, as quoted by Belidor,* writes, "What I say here is not to give room for believing, "that Mr. Savery, who has since published this invention "at London, is not actually the inventor. I do not doubt "that the same thought may have occurred to him, as well as "to others, without having learnt it elsewhere." When we consider the whole of the contrivances invented by Savery, as described by himself in 'The Miner's Friend,' we cannot but accord him the praise of very great ingenuity, independent of the merit of having made THE FIRST WORKING STEAMENGINE, (if he was not preceded in that by the Marquis of Worcester); but at all events, of having been the first who introduced it into use. His drawing and description in

* Architecture Hydraulique,' tome ii. p. 309.

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The Miner's Friend,' apply to an engine with two receivers ; but it was soon altered, in practice, to one receiver, as we have described it.

Switzer, in his 'System of Hydrostatics and Hydraulics,' published in 1729, says, "Among the several engines which "have been contrived for the raising of water for the supply "of houses and gardens, none has been more justly surprising "than that for the raising of water by fire, the particular con"trivance and sole invention of a gentleman with whom I "had the honour long since to be well acquainted; I mean "the ingenious Captain Savery, some time since deceased, "but then a most noted engineer, and one of the Commis"sioners of the sick and wounded.

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"It was a considerable time before this curious person, who "has been so great an honour to his country, could, (as he "himself tells us), bring this his design to perfection, on "account of the awkwardness of the workmen who were necessarily to be employed in the affair; but at last he conquered all difficulties, and procured a recommendation "of it from the Royal Society, in Trans. No. 252, and soon "after, a patent from the Crown, for the sole making this engine. And I have heard him say myself, that the very "first time he played it, was in a potter's house at Lambeth, "where, though it was a small engine, it forced its way "through the roof."

We think it right to add that the language used by Savery in his Miner's Friend,' in treating of the advantages, whether ascertained or prospective, of his invention, presents a strong contrast, in point of plainness, simplicity, and modesty, to the more high-flown phrases in which the Marquis of Worcester magnifies the performances of his "semi-omnipo"tent" engine. Savery was evidently a practical man, possessed of great common sense as well as ingenuity; and although it would probably be wrong to deny to Lord Worcester the possession of a good deal of the second of those qualities, it may well be doubted how far he is entitled to claim any very considerable share of the first.

Savery, in the second chapter of his 'Miner's Friend,'

entitled "Of the uses that this Engine may be applied unto," enumerates-1. The working of mills, by raising water, afterwards to be employed in a steady stream in turning waterwheels; 2. The supplying palaces, or noblemen's and gentlemen's houses, with cisternfulls of water, for domestic use throughout the house, for fountains, or in case of fire; 3. The serving cities and towns with water; 4. The draining of fens and marshes; 5. "I believe," he says, "it may be made very "useful to ships; but I dare not meddle with that matter, "and leave it to the judgment of those who are the best "judges of maritain affairs;" 6. The draining of mines and coal-pits: all of which purposes may, he considers, be answered at far less cost by using his engine than by employing horsepower. And with regard to the last, he suggests that in very deep mines there might be a succession of steam-engines placed at various depths in galleries leading from the shafts.

We have already incidentally referred to Papin having, on the appearance of Savery's invention, abandoned his own idea of 1690, and proceeded to make a steam-engine on other principles, with several variations from that of Savery in the construction of the parts. Belidor, quoting from the work of Papin in 1707, says that "from the year 1698," (the date, it will be observed, at which Savery is said to have obtained his patent, and two years subsequent to the first publication of the description of his engine in the first edition of 'The 'Miner's Friend,' in 1696), "he had made a number of experiments by desire of the Landgrave Charles of Hesse Cassel, to raise water by fire, which he had communicated "to divers persons, and among others to Leibnitz, who "answered that he also had entertained the same idea.

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"This work having been interrupted," continues Papin, "would perhaps have been forgotten, had not Leibnitz, in a "letter of 6th January, 1705, done me the honour to ask my opinion of the machine of Mr. Thomas Savery, of which he "sent me the print made in London. Although its construction was a little different from ours, and I had not the "description sent me, I saw at once that the English machine "and that of Cassel were founded upon the same principle,

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" as I showed to the Landgrave; which caused his Highness "to resume the design of pushing on this invention, which, "without doubt, is a very useful one, as will be seen here"after. I can then testify, that it has cost much time, labour, "and expense, to bring it to its present state of perfection. "It would be tedious to particularise all the unforeseen diffi"culties met with, and all the trials which have turned out contrary to expectation; and, therefore, I shall limit myself "to making known how far what we now have is preferable "to what we had done at first, and to what Mr. Savery has "since done, that the public may not be under any mistake "in the choice of these different machines, and may profit, "without trouble, by what has proved so expensive; and "likewise that they may see that their obligation to his Highness is not solely for having formed the first plan, but "for having overcome the difficulties of the first execution, "and brought matters to their present state of perfection."

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Belidor, after this long quotation, goes on to observe― "M. Papin then gives the description of the machine he had executed, and forgets nothing to give it value. But, what"ever he may say, it is very far from being equally ingenious "and complete with that of Mr. Savery, which possesses the advantage of having within itself all the movements it "requires, without any one touching it; whereas the other "cannot act without the help of several men, one of whom at "least is required to give his work uninterruptedly, with con"trivances which render this machine as imperfect as that of "Mr. Savery is complete." It does not, in fact, appear that the engine improved by Papin, after he was made acquainted with Savery's engine, was ever brought into practical use.

It deserves also to be mentioned that Savery, with the same attention to practical utility by which all of his mechanical proceedings seem to have been characterised, was the first to introduce the idea of horse or horse's power, as the measure of the force of an engine; a term which has since become familiar, as expressing a standard at once convenient in its use, and intelligible to every one. Sir Samuel Moreland had said, in 1683, in speaking of steam

when "well governed according to the rules of statics, and "by science reduced to measure, weight, and balance," that "then it bears its burden peaceably, (like good horses), and "thus would be extremely useful to the human race," &c. But that phrase can there be regarded only as a simile used in quite a general sense; while Savery goes on to show that an engine is capable of doing the work not only of as many horses as could at any one time produce an equal effect, but of as many as would have to be kept in order to produce the same effect constantly. "So that an engine," says he, “which "will raise as much water as two horses, working together at "one time in such a work, can do, and for which there must "be constantly kept ten or twelve horses for doing the same, "then I say, such an engine will do the work or labour of "ten or twelve horses." It is true that the modern use of the same standard has been limited to the lower of those two modes of comparison; but it may be doubted whether the other, employed by Savery, is not in truth the more exact one; as an engine can work day and night without requiring rest, while eight hours, or one-third of that period, are usually considered to be sufficient for a horse to work at one time.

Notwithstanding the importance which we now reasonably attach to the engine thus distinctly put forward by Savery, it met with but little acceptance from the miners to whom he addressed his description, and his arguments in favour of its use. Arago says that there was but one exception to their general disregard of the benefits it promised to them; and, as during the term of his patent the inventor does not appear to have made use of any safety-valve, there was evidently considerable danger, with the imperfect workmanship of those days, in using the highly-heated steam which he is said to have ventured to employ.

"I have known Captain Savery," says Desaguliers, "at "York Buildings, make steam eight or ten times stronger "than common air; and then its heat was so great, that it "would melt common soft solder; and its strength was so

* Miner's Friend,' p. 29, 1702.