Water? The answer is, the driving-wheel "free" of the efforts of the conception, the 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 Chapter III.--THE STEAM TURBINE. How a turbine works--The De Laval turbine--The.