“_By allowing me to make short strokes, you prevent my steam piston from getting in its proper cushion, which it would do if it could complete its full stroke. My steam piston is supposed to run up to the end of the cylinder and pass across the exhaust port, cushioning on the confined steam between said port and the cylinder cover._ “_The hand wheels on the side of my steam cylinder are for controlling the amount of this cushion. For slow speeds these cushion valves should be shut tight. When running at ordinary speed or a high rate of speed, these cushion valves should be slightly opened._ “_Once in a while take a look at my water cylinder. See that the packing of the water piston is not set up so tight that it makes me grunt, producing unnecessary friction and wear. Or, perhaps the packing is too loose a fit, or is worn out and needs renewing._ “_Please see that my water valves are seating properly, because if they are not tight I cannot pump as much water as I ought to do for a given speed. Sometimes the springs on the backs of my water valves need renewing or looking after._ “_If you have not already provided a good suction air chamber for my water cylinder, you ought to do it, because it will prevent the water column in the suction pipe from slapping the face of my water piston at the end of each stroke in a harsh manner and so produce ‘water hammer.’ A good suction air chamber, properly located, saves wear and tear, and makes a pump quiet running._ “_Please keep me nice and clean. I may not be of as much importance as your big engine, but there is no reason why I should not be kept free from dirt and grease. I hate to have oil slobbered all over my steam chest, or my stuffing-boxes left leaking._ “_You will find it pays to keep me in good condition, like a well-groomed horse. Treat me well and I’ll serve you well and long!!!_”—THE ENGINEER. GLOSSARY OF PUMP AND HYDRAULIC TERMS. _Air-bound._ This word applies to both pump and piping and expresses the confinement of air between the discharge valve of the pump and the check-valve or the point of delivery. _Air-cock._ Is the same as a pet-cock and is used to relieve pipes that are air-bound. [Illustration: AIR COCK.] _Annular Valve._ From annular—a ring—_i. e._, a round valve with a hole in the middle. _Area._ The extent of surface, as the area of a piston. _Assembling._ Putting together the parts of a machine. _Atmospheric Pressure._ The pressure of atmospheric air, not only downward but in every direction, this amounts to about 14.7 lbs. per square inch at the sea level. Usually taken at 15 lbs. to facilitate calculations. _Auxiliary._ Something to “help out,” as an auxiliary cylinder or an auxiliary piston. _Ball Check-valve._ One in which a metal ball is used in place of a poppet-valve. [Illustration: BALL CHECK-VALVE.] _Balanced Valve._ A valve having an equal pressure on all sides. See equilibrium valve.