INTO MECHANICAL MOTION. Reciprocating engines--Double-cylinder engines--The function of the fly-wheel--The cylinder--The slide-valve--The eccentric--"Lap" of the valve: expansion of steam--How the cut-off is managed--Limit of expansive working--Compound engines--Arrangement of expansion engines--Compound locomotives--Reversing gears--"Linking-up"--Piston-valves--Speed governors--Marine-speed governors--The condenser 44