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opening upwards, prevents the steam in the larger boiler from flowing into the smaller during this operation. The small pipes, g and n, go to within eight inches of the bottom of each boiler ; by opening their cocks on the outside of the boilers, they serve as indexes for ascertaining when the water in each has nearly evaporated. When steam only comes through either on opening their cocks, the water has sunk beneath their lower orifices; and as these are adjusted to the lowest level at which it ought to stand, it gives notice that a fresh supply is necessary; but if water comes through on opening the cock, the quantity contained in the boiler is sufficient to prevent accidents from its being burnt by the fire beneath it.

The mechanism by which the steam is directed into either of the receivers, is very simple, and will be easily understood by an inspection of tigs. 3 and 4, the part marked m, in tig. 1, and a bird's-eye view of the same part in fig. 2. A slider is attached to an axis or spindle, m, going through the lid of the boiler; when the handle, ã, fixed on this, is moved backwards or forwards, it causes the slider (shown in its two different positions in figs. 3 and 4) to shut the mouth of one of the pipes, 0, 0, and thus interrupts the flow of the steam into that receiver, with which it is connected. The operation of the buoy cock, and the jet cock and its pipe, will be easily understood from an inspection of the figure forming the subject of Plate IV. All the valves or clacks in the pipes being constructed to open upwards, the return of the water, which has been raised to its former place, is effectually prevented.

Such is the arrangement of the parts and action of the celebrated fire-engine of Captain Savery ; and various as the opinions are regarding his claim



DESAĜULIERS. to the merit of being its original discoverer, or first contriver, there is but one with regard to the usefulness, power, and beauty of his invention; and even if it be considered as but a combination of existing ideas, their masterly adaptation marks a mind of the highest order.*

* “Captain Savery,” according to the doctor, “having read the Marquess of Worcester's book, was the first who put in practice the raising of water by fire, which he proposed for the draining of mines. His engine is described in Harris's Lexicon, which, being compared with the Marquess of Worcester's description, will easily appear to have been taken from him, though Captain Savery denied it; and the better to conceal the matter, bought up all the marquess's books that he could purchase in Paternoster-row, and elsewhere, and burned them in the presence of a gentleman who told me this. He said, that he found out the power of steam by chance, and had invented the following story to induce people to believe it, viz. : that having drunk a flask of Florence wine at a tavern, and thrown the empty fask upon the fire, he called for a basin to wash his hands, and perceiving that the little wine left in the Alask had filled up the fask with steam, he took the flask by the neck, and plunged the mouth of it under the surface of the water in the basin, and the water of the basin was immediately driven up into the flask by the pressure of the air: now he never made such an experiment then, nor designedly afterwards, which I thus prove. I made the experiment purposely with about half a glass of wine left in a flask, which I laid upon the fire until it boiled into steam, then putting on a thick glove to prevent the neck of the Aask from burning me, I plunged the mouth of it under the water that filled the basin, but the pressure of the atmosphere was so strong, that it beat the fask out of my hand with violence, and threw it up to the ceiling. All this must have happened to Captain Savery; if ever he had made the experiment, he would not have failed to have told such a remarkable incident, which would have embellished his story," Experimental Philosophy, vol. ii. p. 314.

“This grievous charge," says professor Robison,“ ought to be substantiated by very distinct evidence; yet Desaguliers produces none such, and he was too late to know what happened at the time. His argument is a very foolish one, and gives him no title to consider Savery's experiment as a falsehood; for it might have happened precisely as Savery relates, and not as it happened to Desaguliers. The faet is, Savery


188 We may pass over with brief notice the charge made by Desaguliers, and hy him alone, of Savery obtained his patent in 1699, after a hearing of objections, in which the discovery of the Marquess of Worcester was not mentioned; but, besides this, he had erected several of his engines before he obtained his patent," Mechanical Philosophy, vol. iii. p. 148. 1824.

* Every possible publicity was given, not only to the prin. ciple of his machine, but also to its construction; and yet, dur. ing Savery's lifetime, the Marquess of Worcester's description had never been mentioned. Neither is this tale of destroying the books found in any other anthor. Nor is it stated by Desaguliers before 1746, nearly thirty years after Savery's death, and almost fifty years after the grant of the patent. Desaguliers alludes to the Marquess of Worcester's book: Was the doctor ignorant of the noble inventor having printed two (four) books containing the description? Did the other three become scarce ? Copies of these might have been in existence to have produced against Savery's claim, and destroyed his patent. It is certain that, during his lifetime, Savery is not known to have had any competitor in England to dispute with him the honour of inventing the machine which now bears his name; but a pamphlet being rare at a bookseller's thirty-five years after its publication is not at all an extraordinary cireumstance; and it would, indeed, have been almost a miracle had a copy of the book been found at such a distance of time in that unenviable situation." Stuart, Des. Hist. of Steam Engine, p. 35.

“No contrivance,” says Switzer, (Introduction to a general System of Hydrostatics, 1729). " is more justly surprising than the fire-engine, the particular contrivance and sole invention of a gentleman with whom I had the honour, long since, to be well acquainted. I mean the ingenious Cap, tain Savery, sometime since deceased, but then a most noted engineer, and one of the commissioners of sick and wounded. This gentleman's thoughts were always employed in hydrostatics, or hydraulics, or in the improvement of water-works ; and the first hint from which it is said he took this engine was from a tobacco-pipe, which he immersed to wash or cool it, as is sometimes done. He discovered, by the rarefaction of the air in the tube by the heat or steam of the water, and the gravitation or impulse of the exterior air, that the water was made to spring through the tube of the pipe in a wonderful, surprising manner; though others say, that the learned Marquess of Worcester, in his “Century of Inventions,” (which book I have not seen,) gave the first hiņt for thus raising water



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having copied his machine from the descriptions left by Lord Worcester; and taking advantage of the death of the original inventor, to produce his machine a second time, and claim for it, as for his own idea, that protection which was only to be granted to an original discovery.

Savery, it is admitted, may have read the description in the “Century of Inventions, and he may even have been acquainted with the details of

by fire. It was a considerable time before this ingenious per son, 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 about the affair; and I have heard him say myself, that the first time he played it was in a potter's house at Lambeth, where, though it was but a small engine, yet it forced its way through the roof, and struck up the tiles in a manner that surprised all the spectators." p. 324.

In 1730, Dr. Allen says: “ It is now more than thirty years since the engine for raising water by fire was first invented by the famous Captain Savery, and upwards of twenty years that it received its great improvement by my good friend, the ever-memorable Mr. Newcomen, whose death I very much regret.”. Specimina Ichnographica, p. 17.

Another of his inventions is described by M. de Saumarez, who had invented something similar, and whose scheme was recognised to be the same as Savery's. “It was towed sometime by the side of the ship and sometime by, the stern. The sea-water driving round the lowest and swiftest wheel thereof, and that wheel driving round other wheels, the highest and lowest of which turned round an index covered with glass to show length of way sailed. When it was fair weather and bore before the wind, it showed in a manner the distance sailed, which was performed by hauling on board to view the index, and reputting it off again from the side of the ship into the sea

with great care and precaution lest it should be bruised, which proved cumbersome and troublesome to the seamen, and of no dependence to be made upon, much less when the ship did veer and tack about or kept to the wind. ward ; and that it was useless in a rough sea, and on the whole found less exact than the log-line, and at Captain Bennet's coming home he delivered the instrument to Savery.” Say. marez's Memorial, p. 10. 1717.

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Lord Worcester's machine at Vauxhall, and yet be neither an imitator nor a plagiary. Many of Lord Worcester's contemporaries were alive at the period when Savery got_bis patent; some of them were members of the Royal Society at the time he exhibited his model, and described its construction and action in their apartment, among others, the celebrated Dr. Hooke. It is improbable, therefore, that Lord Worcester's machine, whatever was its construction, could have been unknown or forgotten by many of the emi. nent persons then composing that body; and particularly by Dr. Hooke. The doctor's memory was not one of the least retentive, and his habits of mind, certainly, were not those which, at any period of his long life, would have permitted him to see the merit of a machine of this importance arrogated by a person who had no claim to it; and the more so, as the doctor himself is said to have hinted at the construction of a steam-engine so early as 1678 : * and finally, it is equally improbable, that others were not to be found, whose testimony would have been brought against Savery at the legal hearing of

“After the death of Dr. Robison, says the author of a memoir of Dr. Hooke in the Edinburgh Encyclopædia,

there was a list of Dr. Hooke's inventions found among the professor's papers, which contained the following memorandum:— 1678, proposed a steam-engine on Newcomen's principle. It would have been interesting to have ascer. tained whether this memorandum was made by Dr. Robison before or after his having written the excellent account of the steam-engine in his supplementary articles to the third edition of the Encyclopædia Britannica. The project was either unknown to the professor, at the period of writing the article alluded to, or it was rejected on account of its questionable accuracy:

In the edition of that account lately published, (in his " Mechanical Philosophy," 1823,) no notice whatever is taken of Hooke's idea." Stuart, Des. Hist. of Steam-engine, p, 21. 3d edit. 1825.

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