MODERN STEAM PRACTICE.
156
being left at the top. All the flanges of the pump fittings shouldbe bracketed, and the valve-ehest doors strongly ribbed in thecasting, and secured with deep nuts, the hoop bolts passing roundthe valve ehest, the flanges having strong wrought-iron hoops shrunkon. The arrangements shown are very compact; the bottomof the pump resting on the cistern placed high up above the liftingset, the suction pipe of the latter (Fig. 90) being as long as possiblein Order to make provision for inspecting the valves in the event of
the water accumulating or rising atthe bottom of the shaft; the valvesalso are so arranged that in theevent of the water rising above thedoors they can be drawn out fromthe surface for inspection, and againplaced in.
In the combination of the solidplunger and bücket pump the waterdelivery is equalized; the barrel isaccurately bored out, and fittedwith a gland at the top for theplunger to pass through, making itperfectly air and water tight. Thearea of the plunger is exactly one-half of the area of the pump barrel,consequently at the down stroke,the barrel being full of water, it isforced through the valve in thebücket; and the water being forcedinto one-half of the space, one-halfof the contents of the pump is dis-charged in the down stroke andone-half in the up stroke. Theplunger in this arrangement can bemade to act as an air vessel, thusthe flow of the water is very regu-lär, and the shock of the valves be-comes somewhat easier. This pumpcan be arranged with a solid piston,having suction and delivery valves as in ordinary pumps. Theremust, however, be a passage in Connection with the top of the barrel