Hisfirst Steam-Engine.

455

Chap. 8.]

of water into a vessel from which the air had been expelled by steam, wasof course not new in Savery’s time, although it appears to have been soto him. Switzer gives a different account. “ The first hint from whichit is said he took this engine was from a tobacco pipe, which he immers’dto wash or cool it, as is sometimes done : he discover’d by the rarefactionof the air in the tube, by the heat or steam of the water and the gravitationor impulse of the exterior air, that the water was made to spring throughthe tube of the pipe in a wonderful surprising manner.” a It was an oldpractice of Veteran smokers, when their (elay) pipes became blackenedthrough use, and more particularly when choked or furred up, to placethem in a bright fire tili they became red hot, then to reraove and allowthem to cool. By this Operation they were whitened and purified like theincombustible cloth of the ancients, which was cleansed in the same way.But frequently when taken from the fire the mouths of the pipes wereplunged slowly into water; steam was thus formed, and rushing throughthe tubes, was sometimes preceded, often accompanied, and sometimesfollowed by jets of water. There are however different causes, and farfrom obvious ones, for the liquid issuing through tobacco pipes under suchcircumstances, so that it is difficult to perceive what inference Savery drewfrom the experiment.

But whatever may have led Savery to the subject of steam, he had sofar matured his ideas respecting its application to raise water as to erect

several engines, and to secure apatent as early as 1698. In Juneof the following year he submitteda working model to the Royal So­ ciety , and made successful experi-ments with it at the same time. Afigure ol^ this engine was publishedin the Transactions of that year, andmay also be found in the first volumeof Lowthorp’s Abridgment. No.193 is a copy. It consisted of aclose boiler, B, set in a brick furnaceA, and two receivers D D support-ed on a stand, and made of strongcopper and air-tight. A suction pipewhose lower end descends into awell, or other place whence wateris to be raised, (which may be about24 feet below D D) and whose up-per part, divided into two branches,communicates with the top of thereceivers. Each branch is furnishedwith a valve at E E, opening up-wards, to prevent the water from

G

c

9 !'I§e»

laasgäj'ä

No. 193. Savery’s First Engine. A. D. 1698. returning when once raised. The

lower part of the forcing pipe G hasalso two branches, F F, which communicate with the bottom. of the receivers,and these branches have also valves, E E, like the others opening upwards.Each receiver has a communication with the upper part of the boiler bysteam pipes and cocks C C.

The Operation was as follows ;—The boiler was two thirds filled with

Hydrostatics, edition of 1729, page 325.