Papin states that this invention is suited to draw water from mines, to throw bombs, and to row vessels against wind and tide. For this last purpose, he pro posed to fix on the sides of the vessels revolving row ers or paddle wheels, and by means of three or four of his new invented cylinders, to give a combined mo tion to the axis on which the paddle wheels are fixed. In order to give this motion to the wheels, the piston rods were to be toothed so as to drive small toothed wheels fitted on the axis of the paddle wheels, when ever the pressure of the atmosphere caused the pis tons to descend into their respective cylinders. In order to make the motion of the paddle wheels unin terrupted,several cylinders were to work in succession one acting while the rest were heating. The toothed wheels on the axis of the paddles were to have ratch ets and clicks that they might revolve freely in an op posite direction to the ixis when the pistons were ris ing in their cylinders, but when the pistons were pressed down into the cylinders, the clicks would catch in the teeth of their ratchets, and carry the axis round with the toothed wheels.
This scheme was reprinted in 1695 in the Recucil de diverses pieces louchani quelques nouvelles Machines par D. Cassel 1695, in which he describes a new invented furnace and revolving bellows, which he had contrived to boil water by an internal fire-place, surrounded on ali sides by the water; and he endea vours to show how it could be applied to heat the ck finders of his engine with such increastut rapidity as to perform four strokes in a minute. Papin made one of these machines in 1698, but before he had put it to the test of experiment it was destroy ed by an accident.
It is impossible to peruse these details without be ing convinced that this ingenious author had advanc ed a considerable way in the construction of the steam engine, and had almost invented some of its most use ful applications. We feel much satisfaction in hav ing an opportunity of acknowledging the merits of this ingenious foreigner, as we had been induced, on the authority of Dr. Robison, and by an imperfect exami nation of the subject, to do injustice to the genius of this able author, when we had occasion to discuss the subject in another work.* Notwithstanding all these attempts to construct a steam engine, no machine of this kind had yet been executed and applied to actual use. The honour of this great step was reserved for Captaint Thomas Sa very, treasurer to the commissioners of sick and wounded. In a pamphlet entitled the Miner's Friend, published in 1696, he described a steam engine in which water is raised not only by the expansive force of steam, but also by its condensation, the water being raised by the pressure of the atmosphere into receiv ers, from which it is forced to a greater height by the elastic force of the steam. After having erected several
of these engines, Savery took out a patent, in 1698, for a new invention "for raising water and occasioning motion to all sorts of mill work." In June 1699, he exhibited a working model to the Royal Society, who printed in their transactions for that year a drawing and description of it; but the most complete account of it appeared in a small pamphlet of eighty-fou• pages I2mo. which Mr. Savery published in 1707, under the title of "The Miner's Friend, or an Engine to raise Water by Fire described; and the manner of fixing it in Mines, with an account of the several uses it is ap plicable unto, and an answer to the objections made against it." This hook was separately addressed to King William III. to whom the engine had been shown at Hampton Court.
This engine, which is perfect so far as it goes, dis plays much ingenuity. The following is Savery's own description of it, with some additions as given in Har ris's Lexicon Teelinicurn, vol. i. Art. ENGINE.
A A The furnaces which contain the boilers. III, B2. The two fire places.
C The funnel or chimney which is common to both furnaces. In these two furnaces arc placed two vessels of copper, which I call boilers, the one large as L, the other small as D.
D The small boiler contained in the furnace, which is heated by the fire at B 2.
E The pipe and cock to admit cold water into the small boiler to fill it.
I' The screw that covers and confines the cock E to the top of the small boiler.
• A small guage cock at the top of a pipe going within eight inches of the bottom of the small boiler.
H H A larger pipe which goes the same depth into the small boiler.
• I A clack or valve at the top of the pipe II, (opening upwards.) K K A pipe going from the box above the said clack or valve, into the great boiler and passing about an inch into it.
L L The great boiler contained in the other fur nace, which is heated by the fire at II 1.
M, Fig. 9. The screw with the regulator which is moved by the handle Z, and opens or shuts the apertures at which the steam passes out of the great boiler into the steam pipes 0, O.
N n Two small guage pipes which go down into the great boiler, one of which N has its lower end a little above the proper depth of water, and the other n a little below it, so that when N gives steam upon turning the cock, and n water, the water is at its proper height.