The labour of turning the regulator Z, and the han dle h of the condensing watercock, may be easily per formed by a boy, though Mr. Savery recommends the employment of an intelligent workman. The use of the small boiler D is to replenish the large one L with water, which sinks in it Abut one foot in one and a half or two hours. For this purpose, the small boiler D is supplied with water from the force pipe by a small pipe and cock B, Figs. 8 and 10, which is closed when the boiler D is nearly full. A fire is then lighted in the furnace B r, and in consequence of the elasticity of the steam which it produces being stronger than that in the boiler I., it presses upon the water in D, Fig. 10, forces it up the pipe MI, and through the cock 1 (which is for this purpose open) into the boiler L, into which it will flow till the surface of the water in D has descended to the lower end of the pipe H, which is within eight inches of the bottom. The size of the boiler D is such, that it supplies L with exactly one foot of water. In order to ascertain when the boiler L requires more water, we have only to turn the guage cocks N, n. If steam arises from N and water from n, as will happen in the state shown in Fig. 10, then no water is required, but if steam issues from n there is then a want of water, and if water should issue from N there is more than is necessary.
After giving the description of his engine, Mr. Savery enumerates the following purposes to which it may be applied, viz: 1. Raising water for turning all sorts of mills. 2. Supplying palaces, noblemen's and gentlemen's houses with water, and affording the means of extinguishing fires therein by the water thus raised. 3. Supplying cities and towns with water. 4. Draining fens and marshes. 5. For ships.* 6. Drain ing mines with water, and preventing damps in these mines.
The safety valve, which was invented by Papin in 1681, does not seem to have been used by Mr. Savery in any of his engines ; and it is also evident from the preceding description of his engine, that he was not the inventor of the injecting pipe, or of the principle of condensing by injection, an honour which Mr. Watt has, by mistake, ascribed to him. t In examining with some care the various accounts which have been given of Mr. Savery's labours, and the details of his engine, we are strongly disposed to believe, with Mr. Farey, that the whole of it was his own invention, and that he was even unacquainted with the previous contrivance of the Marquis of Wor cester. The story told by Dr. Desaguliers, that Savery borrowed his invention from the Marquis of Worces ter; and that, in order to conceal the matter, he bought up all the Marquis's books that he could pur chase in Paternoster Row, and burned them in the presence of a gentleman who mentioned the thing to Dr. Desaguliers, is so improbable that we cannot give it credit ; and even if we did, it could not affect the ingenuity and originality of Savery's engine. What ever merit we may attach to the contrivance of the Marquis of Worcester, and in %%hatever manner we may apportion a certain share of merit to the dif ferent candidates to whom national partiality may have adjudged the invention of the steam engine, there cannot, we think, be any doubt that Mr Savery stands at the head of the list, and is more entitled to have his' name associated with the invention, the construction, and the introduction of the steam engine into actual use, than any other individual that has yet been named.
Dr. Papin, who had still continued to direct his at tention to the subject of the steam engine, published in 1707 a small tract, entitled Nouvelle maniere pour lever Nall par le force du feu, mis en lumiere, Cassel. Papin admits in this work that he had seen the en graving of Savery's engine, which M. Leibnitz had sent to him from London ; and, therefore, he does not bring forward his engine as having the precedence of Savery's, but merely as a construction which possesses superior advantages. lie proposed to the Royal So ciety, of which he was a member, to bear the expense of constructing an engine upon his plan ; but this learned body, who had a communication with Mr. Savery on the subject, do not seem to have attached any value to the contrivance of Papin, which we have represented in Fig. 11.
A copper boiler A communicates by means of a pipe Z with the cylinder I, which is connected by a curve pipe X to an upright OQ, which rises nearly to the top of the cylinder RR. This cylinder, which is air tight, is furnished with a pipe W and stop-cock P, Plate Fig. 11. Another pipe terminating in a funnel K with a stop-cock at M branches off from the bent pipe X. The pipe Z has a stop-cock at C, and another small pipe at E also furnished with a stop-cock. A safety valve F, of which Papin is the undoubted in ventor, is placed above the boiler A. In the cylinder I is a piston or float N made of thin plates of metal, forming a hollow cylinder which floats on the surface of the water. A pipe and stop-cock D is inserted in the cylinder 1. When steam is generated by lighting a fire beneath the boiler A, the cock C is opened to allow it to rush into the pump cylinder I, which is nearly filled with water. The elastic force of the steam depresses the float n n, and thus forces the water beneath it through the valve 0, and up the pipe OQ into the receiver RR, the air in which it of course con denses. The stop-cock p is then opened, and the water pressed out by the elasticity of the condensed air in the receiver rushes out through the cock P, and strikes the float-boards U, S, X, of a wheel which gives motion to any other machinery. When the float n 7/ has descended to N, the farther admission of steam into I is prevented by turning the cock C, and the steam above the float is allowed to escape into the air by the cock D. At the same time the stop-cock M is opened to allow the water in the funnel K to descend and raise the float 72 n to its first position as in the figure. The cocks D and M are now shut, and C is opened to re-admit the steam from the boiler, and impel more water against the wheel, which will thus be kept in constant motion. A pipe and cock is placed at E to allow the air in the boiler to escape when it is first filling with steam. A similar pipe empties the pipe X of water.