All About Engines

Raising Steam 101 valve, e, which is operated by the steam itself. In this way the waste of power in moving heavy levers is avoided, and the only mechanical friction outside the valve chamber is that produced in the small light levers which move the impulse valve. While the steam cylinder, a, valve chambers, and piston are made of cast-iron, and the piston rod of steel, the pump piston is made of gun-metal with ebonite rings, the liner, valves, and valve seatings of the same metal, and the pump rod of manganese bronze in order to resist the action of the water. The pump is, as will be seen from the valves, double-acting, forcing water at every stroke. It is made in sizes ranging from one with a steam cylinder 4J inches in diameter and a pump barrel of 3 inches, to one with a steam cylinder of 14 inches and a pump barrel of io| inches. The stroke of the smaller one is 9 inches and of the larger 2 feet, while the smaller pumps 600 and the larger 10,000 gallons per hour. Ten thousand gallons looks a large quantity for feeding boilers, but it is only 100,000 lb., and there are many boilers which will evaporate 30,000 or 40,000 lb. per hour, so that this pump would keep only two or three of them going. It is far more striking when a week or a year is considered. Suppose, for example, the plant runs for an average of ten hours a day for six days a week for a year. Then the quantity of water required will be 100,000 gallons a day, 600,000 gallons a week, and 31,200,000 gallons a year. This would form a lake nearly 182 yards long, 100 yards wide, and 10