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"Steam is admitted under pressure for a boiler into a metal cylinder behind a piston, as represented in figure 14. Its pressure drives the piston forward, doing useful work. When the piston has moved through a part of its stroke the steam supply is cut off, the stroke is completed by the expansion of the steam confined in the cylinder. By the first law of thermodynamics this expansion cools the steam, since work is done in the process; but the expansion is not adiabatic, since the cylinder and piston give up some heat to the steam within. At the end of the stroke the exhaust valve opens and the cooled steam escapes into the atmosphere or condenser through exhaust pipe A. The operation is then repeated on the other side of the piston." Louis Derr, 1911

Mechanical Drawing of a Metal Cylinder

"Steam is admitted under pressure for a boiler into a metal cylinder behind a piston, as represented…