In 1698 he obtained a patent from William the Third "for raising water, and occasioning motion to all sorts of mill-work, by the impellant force of fire;" and in 1699 he exhibited a model of his engine before the Royal Society, a description and illustration of which is given in their Transactions, vol. xxi. p. 228. In 1702 he published a work entitled The Miner's Friend, written in a lively and interesting style, and containing a full and circumstantial account of the arrangements and operation of the engine. The following is the description, which is worthy of a place here, as an example of mechanical description, and as giving a notion of the merits of Savery as an inventor. In fig. 8, which is a per

of

fig. 8.

spective view of the whole apparatus, a a are the furnaces which contain the boilers; b1, b2, the two fire-places; c, the funnel or chimney, which is common to both furnaces. In these two furnaces are placed two vessels 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 62 ; e, the pipe and cock to admit cold water into the small boiler to fill it; f, the screw that covers and confines the cock e to the top of the small boiler; g, a small gauge-cock at the top of a pipe going within eight inches of the bottom of the small boiler; h, a larger pipe, which goes the same depth into the small boiler; i, a clack or valve at the top of the pipe h (opening upwards); k, a pipe going from the box above the said clack or valve in the great boiler, and passing about an inch into it. 71, the great boiler contained in the other furnace, which is heated by the fire

at b1; m, 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 oo; n, a small gauge-cock at the top of a pipe which goes halfway down into the great boiler; o, o, steam-pipes, one end of each screwed to the regulator, the other ends to the receivers p1,p2, to convey the steam from the great boiler into these receivers; p1, p 2, copper vessels called receivers, which are to receive the water which is to be raised; q, screw joints by which the branches of the water-pipes are connected with the lower parts of the receivers ; r 1, r 2, r 3, r 4, valves or clacks of brass in the water-pipes, two above the branches 0, and two below them; they allow the water to pass upwards through the pipes, but prevent its descent; there are screw-plugs to take out on occasion, to get at the valves r; s, the forcing pipe, which conveys the water upwards to its place of delivery, when it is forced out from the receivers by the impellant steam; t, the sucking pipe, which conveys the water up from the bottom of the pit, to fill the receivers by suction; a square frame of wood, or a box with holes round its bottom in the water, encloses the lower end of the sucking pipe, to keep away dirt and obstructions; x, a cistern with a buoy-cock coming from the force-pipe, so as it shall always be kept filled with cold water; y, a cock and pipe coming from the bottom of the said cistern, with a spout to let the cold water run down on the outside of either of the receivers, p 1, p2; z, the handle of the regulator, to move it by, either open or shut, so as to let the steam out of the great boiler into either of the receivers."

In working the engine, “the first thing is to fix the two boilers of the engine in a good double furnace, so contrived that the flame of the fire may circulate round and encompass the boilers to the best advantage, as you do coppers for brewing. Before you make any fire, unscrew the two small gauge pipes and cocks, g, n, belonging to the two boilers, and at the holes fill the great boiler / two-thirds full of water, and the small boiler d quite full; then screw in the said pipes again, as fast and tight as possible, and light the fire under the large boiler at b1, to make the water therein boil; and the steam of it, being quite confined, must become wonderfully compressed, and therefore will, on the opening of a way for it to issue out (which is done by pushing the handle z of the regulator as far as it will go from you), rush with a great force through the steampipe o into the receiver p 1, driving out all the air before it, and forcing it up through the clack r into the force-pipe, as you will perceive by the noise and rattling of that clack; and when all the air is driven out, the receiver p 1 will be very much heated by the steam. When you find it is thoroughly emptied, and is grown very hot, as you may both see and feel, then pull the handle z of the regulator towards you, by which means you will stop the steam-pipe o, so that no more steam can come into the receiver p 1, but you will open a way for it to pass through the other steam-pipe, o, and by that means fill the other receiver, p 2, with the hot steam, until that vessel has discharged its air, through the clack r 2, up the force-pipe, as the other vessel did before.

"While this is doing, let some cold water be poured on the first-mentioned receiver, p1, from the spout y, by which means the steam in it being cooled and condensed, and contracted into a very little room, a vacuum or emptiness is created; and consequently the steam pressing but very little, if

at all, on the clack r 3 at the bottom of the receiver p 1, there is nothing there to counterbalance the pressure of the atmosphere on the surface of the water at the lower part, v, of the sucking-pipe t; wherefore the water will be pressed up, and ascend into and fill the receiver p 1, by what is commonly called suction: the water as it rises lifts up the clack or valve r3, which afterwards falling down again, and shutting close, hinders the descent of the water that way. The receiver p 2 being by this time emptied of its air, push the handle of the regulator from you again, and the force of the steam coming from the great boiler will be again admitted through o, and will act upon the surface of the water contained in the receiver p 1, which surface only being heated by the steam, it does not condense it, but the steam gravitates or presses with an elastic quality like air, and still increasing its elasticity or spring until it counterpoises, or rather exceeds, the weight of the column of water in the receiver and pipes, which it will then necessarily drive up, through the passage q r, into the force-pipe s. The steam takes up some time to recover its power; but it will at last discharge the water out at the top of the force-pipe s, as it is represented in fig. 8. After the same manner, though alternately, the receiver p 2 is filled with water by means of the suction, and then emptied by the impellant force of the steam, whereby a regular stream is kept continually running out at top of the force-pipe s; and so the water is raised very easily from the bottom of the mine, &c., to the place where it is designed to be discharged. I should add, that after the engine begins to work, and the water is risen into and hath filled the force-pipe s, then also it fills the little cistern x, and by that means supplies the spout or pipe yy, which I call the condensing pipe, and which by its handle can be turned sideways over either of the receivers, and is then open; by this spout cold water is conveyed from the force-pipe, to fall upon the outside of either of the receivers when thoroughly heated by the steam, in order to cool and condense the steam within, and make it suck (as it is usually called) the water up out of the well into that receiver. It is easy for any one that never saw the engine, after half an hour's experience, to keep a constant stream; for on the outside of the receiver you may see how the water goes out as well as if the receiver were transparent; for as far as the steam continues within the receiver, so far is that vessel dry without, and so very hot as scarce to endure the least touch of the hand; but as far as the water is withinside of the said vessel, it will be cold and wet where any water has fallen on it, which cold and moisture vanish as fast as the steam in its descent takes place of the water. But if you force all the water out of the receiver, the steam, or a small part thereof, will go through the clack r 1 or r 2, and will rattle that clack so as to give notice to move the handle of the regulator, and then the steam begins to force the water out from the other receiver p 1, without the least alteration of the steam, only sometimes the stream will be rather stronger than before, if you pull the handle before any considerable quantity of steam be got up the clack r; but it is much better to let none of that steam go off, for that is but losing so much strength; and it is easily prevented by pulling the regulator some little time before that receiver which is forcing is quite emptied. This being done, turn the cock o, or condensing pipe y, of the cistern x, over the empty receiver, so that the cold water proceeding from x may run down through y, which is never opened but when turned over

one of the receivers, but when it stands between them is tight and stanch. This cold water, falling on the outside of the receiver, by its coolness causes that steam which had such great force just before to condense and become an empty space, so that the receiver is immediately refilled by the external pressure of the atmosphere, or what is vulgarly called suction, whilst the other receiver is emptying by the impellant force of the steam; which being done, you push the handle of the regulator from you, and thus throw the force into the other receiver, pulling the condensing pipe over the receiver p 2, causing the steam in that vessel to condense, so that it fills while the other empties; the labour of turning these two parts of the engine, viz. the regulator and condensing water-cock, and tending the fire, being no more than what a boy's strength can perform for a day together, and is as easily learned as their driving of a horse in a tub-gin."

The method by which Savery managed to keep up the supply in the large boiler, for the purposes of evaporation, is highly ingenious, and is indicative of his inventive powers. Let a, fig. 9, represent the small

k

n

L

fig. 9.

boiler, which is supplied with water from the force-pipe s by the pipe e, supplied with a stop-cock (fig. 8); a pipe, h, descends within eight inches of the bottom of the boiler, and is provided with a valve, i, opening upwards; this pipe is connected with the large boiler l. The following is the operation, as described in the inventor's own words: "When it is thought fit by the person tending the engine to replenish the great boiler (which requires about an hour and a half or two hours to the sucking one foot of water), he turns the cock e, so that there can be no communication between the force-pipe s and the small boiler d, and putting in a little fire under the small boiler at b 2 (fig. 8), the water will then grow presently hot; and when it boils, its own steam, which hath no vent out, will gain more strength than the steam in the great boiler. . . . The water in the small boiler, being depressed by its own steam pressing on its surface, will force the water up the pipe h, through k, into the great boiler 7; and so long will it run, till the surface of the small boiler d gets to be as low as the bottom of h; and then the steam and water will run together, and by its noise, and rattling of the clack i, will give sufficient assurance to him that works the engine that the small boiler hath emptied and discharged itself into the greater one 7, and carried in as much water as is then necessary; after which, by turning the cock e again, you may let

fresh cold water out of the force-pipe s (see fig. 8) into the lesser boiler d, as before; and thus there will be a constant motion and continual supply of the engine, without fear or disorder. And inasmuch as from the top of the small boiler d to the bottom of the pipe h there is contained about as much water as will replenish the great boiler one foot, so you may be certain it is replenished one foot of course." Captain Savery also introduced a contrivance by which the depth of the water in the boilers could be ascertained; this he termed a "gauge-cock," the principle of which is illustrated in fig. 9, at c, n, which are pipes continued down to within eight inches of the bottom of the boilers. When the attendant is desirous of knowing when the great boiler wants replenishing, he opens the stop-cock in connection with the pipen if water issues from it, the supply of water is sufficient; if steam issues from it, it is an evidence that the boiler requires a supply of water. By the cock c it is easily ascertained whether the small boiler requires a supply of cold water from the forcepipe s. This contrivance of the gauge-cock is still in use to the present day, the best evidence as to the practical value of Savery's ingenuity.

Such is a description of Savery's celebrated "fire-engine," an invention remarkable alike for the judiciousness of its arrangements, and the practical purposes for which, at the period, it was introduced. Considerable discussion has arisen as to whether Savery really invented the engine, or derived his ideas from other sources, as the invention of the Marquis of Worcester. Desaguliers details an evidently got-up story of Savery having bought up the copies of the pamphlet of the marquis, with a view to do away with all evidence of priority of invention on the part of the marquis. There is no evidence that this was done by Savery: on the contrary, all evidence goes to prove the fact that it was extremely unlikely for him to endeavour to detract from the fame of the marquis by way of gaining for himself a reputation. The buying up the pamphlets of the marquis would have been a useless labour, for it is altogether improbable that all recollection of an engine erected at Vauxhall, as reported by the Grand Duke of Tuscany, should have vanished from the minds of many who would have witnessed its action then alive; moreover many of the contemporaries of the marquis were then alive, at the period when Savery introduced his engine, some of them also members of the Royal Society, before which Savery, as we have seen, displayed a model of his engine. But the ingenuity of the arrangements of the engine itself conveys with it, we think, the undoubted stamp of originality. One honour-and that a high one-can at all events be ascribed to Savery without dispute, and that is of being the person who introduced into extended use an invention calculated to be of high practical value; and this labour, the work of which the world is not slow to estimate highly, he performed in the face of what he termed the "oddest and almost insuperable difficulties," with a perseverance and indomitable courage entitled to the highest commendation; and after all, he who, in spite of the opposition of prejudice and interest, succeeds in introducing into extended use inventions calculated to be of service in the promotion of the interests of humanity, is entitled to a higher reward, and to have the value of his labours judged of from a higher standard, than he whose services are confined to the mere discovery or elaboration of a mechanical or philosophical invention.

In the volume on Natural Philosophy in this series the subject of "at