14; engines, 44; engines, reciprocating, _45_; expansive working of, 59, 81; gauge, 36; gauge, principle of, 37; turbine, 74; turbine, De Laval, 76, _77_; turbine, Hero's, 74; turbine, De Laval, 76, _77_; turbine, Hero's, 74; turbine, Parsons.