Halting circulation of current in dynamo circuit, 163. Diver's feats, 338; helmet, _336_; lamp, _338_. Donkey-engines, 68. Doorstop, self-closing, 344. Double-cylinder engines, 47. Draught, forced, 28, _29_; induced, 29. Drum and fusee, _414_. Durability of motor-car engine, 96. D-valve, 67. Dynamo, alternating, 164, 174; brushes, _172_; compound, 174; continuous-current, 165; multipolar, 169; series wound, _173_; simple, 161, _162_. Ear, the, _271_, _273_; a good, 274, 307; sensitiveness of, 275. Eccentric, _52_, 53; setting of, 53. Edison, Thomas, 310. Edison-Bell phonograph, 310. Electricity, current, 115; forms of, 113; nature of, 112; static, 114. Electric bell, 119, _120_; signalling, 225; slot, 226. Electroplating, 185, _186_. Electro-magnets, 117. Endolymph, 272. Engines, compound, 59; donkey, 68; double-cylinder.