454

STEAM-ENGINE?.

auother pipe to conv ey the water from the force-pipe into thelesser boiler, for the purpose of replenishing the great boiler,when the water in it begins to be almost consumed. When-ever there is occasion for this, the cock is to be turned whichcommunicates between the force-pipe and the lesser boiler,to close it effectually ; at the same time, having put a littlefire beneath the small boiler, which will grow hot, its ownsteam, which has no vent to escape, pressing on its surface,will force the water up another pipe, through an aperture,into the great boiler, and so long will it run till the surfaceof the water gets so low as to be below the bottom of thepipe of communication, then the steam and water runningtogether, will cause the valve (called a clack) to strike,which-will intimate to the operator that it hath dischargeditself into the greater boiler, and carried in as much water asis then necessary; after which, by turning a cock, as muchfresh water is let in as may be necessary ; and then, byturning another cock, new fresh water is let out of a reci-pient into the less boiler, as before; and thus the engine issupplied, without fear of decay, or any delay in the opera-tions; and proper attention in the workmen is only necessaryto prevent disorder in a machine so expensive and compli-cated.

Also, to know when the great boiler wants replenishing,turn the gauge cock, if water come out, it does not need asupply; but if steam alone, then the want of supply is cer-tain. The like with the cock with which the lesser boiler isprepared for the same purpose, when the same state will bemarked by like results. In working this engine, very littleskill and less labour is required: attention is the chiefrequisite; it is only to be injured by want of due care, ex-treme stupidity, or wilful neglect.

The engine above described, does not differ essentiallyfrom that first designed by the inventor, Captain Savery;the chief alteration which now occurs, is only in some fewslight particulars. For instance, the original engine hadonly one boiler, and there was no ready means for supplyingit with water, to remedy the waste occasioned by evapora-tion of steam, without stopping the action of the engine,whenever the boiler was emptied, to such a degree as to riskburning the vessel. After it was replenished, the machinewas of no effect till it boiled again.

The description of the engine formerly mentioned, is tran-scribed from Mr. Savery’s publication, “ The Miner’s Friend,”and which had a subsidiary boiler, with water of a boilingheat, always ready to supply the larger boiler; and the power