MINIMUM when the process is isothermal.Methods of cooling:FASTER heat dissipation from inside of compressor to outside by use of fins over cylinder. Fins facilitate quick heat transfer from air being compressed to atmosphere so that temperature rises during compression can be minimized.WATER JACKET may be provided around compressor cylinder so that heat can be PICKED by cooling water circulating through water jacket. Cooling water circulation around compressor regulates rise in temperature to great extent.