don in 1699, and successful experiments were made with it. Savery spent a considerable time in planning his engine and in perfecting it, and states that he expended large sums of money upon it.

Having finally succeeded in satisfying himself with its operation, he exhibited a model "Fire-Engine," as it was called in those days, before King William III. and his court, at Hampton Court, in 1698, and obtained his patent without delay. The title of the patent reads: "A grant to Thomas Savery, Gentl., of the sole exercise of a new invention by him invented, for raising of water, and occasioning motion to all sorts of mill-works, by the impellant force of fire, which will be of great use for draining mines, serving towns with water, and for the working of all sorts of mills, when they have not the benefit of water nor constant winds.; to hold for 14 years; with usual clauses."

Savery now went about the work of introducing his invention in a way which is in marked contrast with that usually adopted by the inventors of that time. He commenced a systematic and successful system of advertisement, and lost no opportunity of making his plans not merely known, but well understood, even in matters of detail. The Royal Society was then fully organized, and at one of its meetings he obtained permission to appear with his model “fire-engine" and to explain its operation; and, as the minutes read, "Mr. Savery entertained the Society with showing his engine to raise water by the force of fire. He was thanked for showing the experiment, which succeeded, according to expectation, and was approved of." He presented to the Society a drawing and specifications of his machine, and "The Transactions" contain a copperplate engraving and the description of his model. It consisted of a furnace, A, heating a boiler, B, which was connected by

1

"Philosophical Transactions, No. 252." Weld's "Royal Society," vol. i., p. 357. Lowthorp's "Abridgment," vol. i.

pipes, CC, with two copper receivers, D D. There were led from the bottom of these receivers branch pipes, FF, which turned upward, and were united to form a rising main, or "forcing-pipe,"

G

FIG. 11.-Savery's Model, 1698.

G.

From the top of each receiver was led a pipe, which was turned downward, and these pipes united to form a suction-pipe, which was led down to the bottom of the well or reservoir from which the water was to be drawn. The maximum lift allowable was stated at 24 feet.

The engine was worked as follows: Steam is raised in the boiler, B, and a cock, C, being opened, a receiver, D, is filled with steam. Closing the cock, C, the steam condensing in the receiver, a vacuum is created, and the pressure of the atmosphere forces the water up, through the supply-pipe, from the well into the receiver. Opening the cock, C, again, the check-valve in the suction-pipe at E closes, the steam drives the water out through the forcing-pipe, G, the clackvalve, E, on that pipe opening before it, and the liquid is expelled from the top of the pipe. The valve, C, is again closed; the steam again condenses, and the engine is worked as before. While one of the two receivers is discharging, the other is filling, as in the machine of the Marquis of Worcester, and thus the steam is drawn from the boiler with tolerable regularity, and the expulsion of water takes place with similar uniformity, the two systems of receivers and pipes being worked alternately by the single boiler.

In another and still simpler little machine,' which he

Bradley, "New Improvements of Planting and Gardening." Switzer, Hydrostatics," 1729.

erected at Kensington (Fig. 12), the same general plan was adopted, combining a suction-pipe, A, 16 feet long and 3 inches in diameter; a single receiver, B, capable of containing 13 gallons; a boiler, C, of about 40 gallons

capacity; a forcing-pipe, D, 42 feet high, with the connecting pipe and cocks, E F G; and the method of operation was as already described, except that surfacecondensation was employed, the cock, F, being arranged to shower water from the rising main over the receiver, as shown. Of the first engine Switzer says: "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, yet it (the water) forced its way through the roof, and struck off the tiles in a manner that surprised all the spectators."

The Kensington engine cost £50, and raised 3,000 gallons per hour, filling the receiver four times a minute, and required a bushel of coal per day. Switzer remarks: "It must be noted that this engine is but a small one in comparison with many others that are made for coal-works; but this is sufficient for any reasonable family, and other

uses required of it in watering all middling gardens." He cautions the operator: "When you have raised water enough, and you design to leave off working the engine, take away all the fire from under the boiler, and open the cock (connected to the funnel) to let out the steam, which would otherwise, were it to remain confined, perhaps burst the engine."

With the intention of making his invention more generally known, and hoping to introduce it as a pumping-engine in the mining districts of Cornwall, Savery wrote a prospectus for general circulation, which contains the earliest account of the later and more effective form of engine. He entitled his pamphlet "The Miner's Friend; or, A Description of 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 applicable to, and an Answer to the Objections against it." It was printed in London in 1702, for S. Crouch, and was distributed among the proprietors and managers of mines, who were then finding the flow of water at depths so great as, in some cases, to bar further progress. In many cases, the cost of drainage left no satisfactory margin of profit. In one mine, 500 horses were employed raising water, by the then usual method of using horse-gins and buckets.

The approval of the King and of the Royal Society, and the countenance of the mine-adventurers of England, were acknowledged by the author, who addressed his pamphlet to them.

The engraving of the engine was reproduced, with the description, in Harris's "Lexicon Technicum," 1704; in Switzer's "Hydrostatics," 1729; and in Desagulier's “Experimental Philosophy," 1744.

The sketch which here follows is a neater engraving of the same machine. Savery's engine is shown in Fig. 13, as described by Savery himself, in 1702, in "The Miner's - Friend."

LL is the boiler in which steam is raised, and through the pipes 00 it is alternately let into the vessels PP.

Suppose it to pass into the left-hand vessel first. The valve M being closed, and r being opened, the water con

tained in P is driven out and up the pipe S to the desired height, where it is discharged.

The valve r is then closed, and the valve in the pipe 0; the valve M is next opened, and condensing water is turned upon the exterior of P by the cock Y, leading water from the cistern X. As the steam contained in P is condensed, forming a vacuum there, a fresh charge of water is driven by atmospheric pressure up the pipe T.

Meantime, steam from the boiler has been let into the right-hand vessel Pp, the cock W having been first closed, and R opened.