Chat. XVII.

PUMPS.

1175

Fig. 1786. TKEMTHICK’S

PRESSURE-ENGINE.

over, rising no higher by each successive stroke, and occasioning noadditional compression of the air in the vessel. But if the aper-ture of the main is diminished to half its size, the whole of thewater cannot pass during the stroke; consequently a portion goesinto the air-vessel, and increases the compression of the air includedwithin it.

Trevithick 's Pressure Engine resembles one mentioned byBelidor , although it may be considered more perfect in its ar- /fihrangement.

Chain Pumps .— As every ship of war is provided with a numberof chain and hand pumps, great attention has been paid to theirconstruction. Mr. Cole was the first to rectify their numerousdefects, adding a contrivance by which the chain could be easilytaken up and repaired. The old chain pumps required sevenmen to raise a ton of water in seventy-six seconds, and Mr. Colewas enabled to do the same work in forty-three seconds.

Mr. Smcaton contrived a hand-pump for the use of ships,calculated to remedy the defect of delivering the water on themain deck, which was the ordinary custom; thus lifting the waterconsiderably higher than was necessary: to obviate this, he intro-duced horizontal wooden pipes to carry ofT the water through theship’s sides, at as low a level as possible: one end of these pipesproceeded from the upright trunk of the pump, and the other wasfitted into boxes, or short wooden tubes, let in through the ship’sside, and caulked above the low water line; these side pipes wereclosely jointed with the boxes in the ship’s sides at one end, andat the other end into strong planks, which were bolted against thesides of the pump, in order that the side pipes might he got outand in without disturbing the pump, which was a sucking-pump with its bucket workedby a lever upon the deck, over it. From the top of the pump a stand-pipe was carriedup to the main deck, oras high as was thoughtnecessary to prevent thewater running back intothe ship, over the top, whenthe sea rose above the ori-fice of the side pipe. Thepump had three handles,which four men worked ata time; they effected 25strokes per minute, andmoved the pump-rod 17^inches up and down eachstroke.

Kingston's Ship Pump con-sists of 2 brass cylinders, 4inches in diameter, at the bot-tom of which is a pipe com-municating with each. Thespace around and betweenthe cylinders and the casingof the pump serves as anair-chamber, by w’hich thewater is kept under com-pression. The supply ofwater is through a hose,screwed on to the lowerpipe, and the action of thesolid piston is the same asthat of the force-pump :water is thrown out bythis pump in a continuedstream through the eductionpipe when used for ordinarypumping, or through aflexible hose when it is em-ployed to extinguish fire.

>1:

Fig.1787.

KINGSTON S SUU’-FCMP.