DRIVEN MACHINES 101 



power proved rather uncertain Mariners" adopted the 

 gasoline engine, usually a two horsepower engine. 



The second water storage plan was the air-tight steel 

 water-tank to be placed in the cellar or in a pit under- 

 ground. The same pump and power supplies the water 

 for this system, but it also requires an air-pump to sup- 

 ply pressure to force the water out of the tank. 



The third plan forces the water out of the well by air 

 pressure, as it is needed for use. No water pump is 

 required in this system; the air-compressor takes its 

 place. 



Suction-Pumps. The word suction, when applied to 

 pumps, is a misnomer. The principle upon which such 

 pumps work is this : The pump piston drives the air 

 out of the pump cylinder which produces a vacuum. 

 The pressure of the atmosphere is about fifteen pounds 

 per square inch of surface. This pressure forces suffi- 

 cient water up through the so-called suction pipe to fill 

 the vacuum in the cylinder. The water is held in the 

 cylinder by foot-valves or clack-valves. As the piston 

 again descends into the cylinder it plunges into water 

 instead of air. A foot-valve in the bottom end of the 

 hollow piston opens while going down and closes to 

 hold and lift the water as the piston rises. Water 

 from the well is forced by atmospheric pressure to fol- 

 low the piston and the pump continues to lift water so 

 long as the joints remain air-tight. The size of piston 

 and length of stroke depend on the volume of water 

 required, the height to which it must be lifted and the 

 power available. A small power and a small cylinder 

 will lift a small quantity of water to a considerable 

 height. But increasing the volume of water requires a 

 larger pump and a great increase in the power to op- 

 erate it. The size of the delivery pipe has a good deal 



