Modifications of Savery’s Engine.

461

Chap. 8.]

chine : a device like it would naturally be the result of tbe experimentwith the wine flask, and even without it, when his thoughts were o needirected to raising water by steam. Moreover, Savery was ignorant ofthe safety-valve, the very thing wanted to remove the most formidableobjection to his machine; and yet, as we have shown, he might havefound it in some populär Works on chemistry and distillation,—besideswhich, Papin’s improved application of it had been published severalyears. (The single machine figured No. 194 was erected by Saveryhimself" as late as 1711 or ’12, and it had no safety-valve.)

But whether he derived the hint from Worcester or not, he is entitledto all the honor he has received. He was the first effectually to introducethe device, and the first to publish a description of it in detail. He con-cealed nothing, but, like a sensible and practical man, explained the whole,and left it to its own merits. No one’s Claims to a place in the history ofthe steam-engine were better earned, whether he be considered the rein-ventor, or improver only of Worcester ’s 68th proposition. There areseveral points of resemblance in the characters of Savery and Oliver Evans .By their energy and indomitable perseverance they forned their inventionsinto public notice in spite of public apathy, and so worked their way intothe temple of honorable fame. Both published curious pamphlets, thatwill preserve their names and inventions from oblivion.

But Savery’s steam-ehgine does not belong to the same family as themodern one, nor can he be said to have contriSuted to the invention of thelatter, except so far as making his contemporaries more familiär with themechanical properties of aqueous vapor. ’Tis true he employed this fluidin close vessels, and so far he succeeded; but his ideas seem to have beenwholly confined to its application to raise water, and in the most directmanner—hence he never thought of pistons. Had he turned his attention toimpart motion to one of these, he would have left little for his successorsto do ; but as it was, he did not lead engineers any nearer to the pistonengine. He proposed to propel machinery by discharging the water heraised upon an overshot wheel; hence his patent was “ for raising water,and occasioning motion to all sorts of mill work.” But this was obviouslyan afterthought, an accidental result, ratber than one originally designedor looked for. A piston and cylind er only could have given his machinea permanent place in the arts, either as a hydraulic or a motive one. Heaceomplished almost all that could be realized without them. The mostsplendid talents of the present times could have done little more. Papinabandoned the piston and cylinder, and in doing so quenched a halo ofglorv that would have shone round his name for ever ; and Savery, forwant of them, notwithstanding his ingenuity, perseverance and partialsuccess, lived to see his device in a great measure laid aside. Saverydied about the year 1716.

As Savery’s engine became known, several additions to and modifica-tions of it were proposed. A few of these may be noticed :—

Drs. Desaguliers and Gravesande, from some experiments, concludedthat single engines were more economical than double ones—a singlereceiver being “ emptied three times whilst two succeeding ones [of adouble engine] could be emptied but once a piece.” Of single enginesDesaguliers erected seven between the years 1717 and 1744. “The firstwas for the late Czar, Peter I, for his garden at Petersburgh, where itwas set up. The boiler of this engine was spherieal, (as they must all bein this way, when the steam is much stronger than air) and held betweenfive and six hogsheads; and the receiver held one hogshead, and wasfilled and emptied four times in a minute. The water was drawn up by