458

Savery’s Double Engine.

[Book IV.

and will draw yoa water 500 or a 1000 feet high, -were anj pit so deep.- - - - - I dare undertake that this engine shall raise you as much waterfor eight-pence, as will cost you a Shilling to raise the like with your oldengines.” The original figures in the Miner’s Friend were inserted inHarris’s Lexieon Technicum, in 1704, and copied int o Switzer’s Hydro-statics in 1729, and by Desaguliers in his Experimental Philosophy in 1744,(which works are before us) and subsequently into almost every treatiseon the steam-engine. No. 195 is a reduced copy : the figure of the fire-man is an addition.

No. 195. Savery’s Double Engine. A. D. 1702.

A detailed description of this elegant apparatus is not necessary, sinceits Operation will be understood from the explanation of the two precedingmachines. It is substantially the same as No. 193, except that this onehas two boilers, which are heated by separate furnaces, G H. The ad ditional boiler Cr was designed merely to supply the other with hot water,and need not therefore divert the attention of the reader in realizing theworking of the essential parts. The upper end of the suction pipe shownat the mouth of the pit consists of two branches, which are connected tosimilar branches on the lower part of the forcing pipe N. The suctionvalves are at B A, and the forcing ones at E F, all opening upwards.