---- ----, torpedo operations during the, 187 Crinoline for divers, 261 Cross bearings, firing by, 70 Current, direction of, 272 ----, measuring the intensity of a, 95 ----, the Voltaic, 270 D. Daniell's signalling battery, 78 Defects observed in the conductivity of cables, 103 ---- of chemical fuses, 24 ---- electrical submarine mines, 29 Defence of harbours by booms, 110 ----, ship, 10 Defences, clearing a passage through torpedo, 111 Defensive purposes, Harvey's torpedo for, 129 ---- torpedo operations, Russian, 193 ---- ----, Turkish, 193 ---- ---- warfare, 13 Definition and properties of a Voltaic cell, 269 ---- of a condenser, 279 ---- potential, 270 ---- the ohm, 281 ---- ---- term explosion, 204 ---- ---- explosive force, 204 ---- ---- polarization, 273 Description of a frictional electric machine, 278 ---- ---- series of firing keys, 81 ---- ---- Yarrow's torpedo boat, 172 ---- ---- Calland's and Marié-Davy's batteries, 275 ---- ---- Siemens' electric light apparatus, 241 ---- ---- Whitehead's fish torpedo, 133 _Destroyer_, Ericsson's torpedo vessel, 160 Destruction of passive obstructions, the, 113 ---- ---- the _Albemarle_, 191 ---- ---- _Duba Saife_, 197 ---- ---- _Suna_, 194 Detector galvanometer, the, 88 Detonating composition, Rain's, 23 Detonation, 206 ---- experiments, Abel's, 216 ----, theory of, 206 Dielectric, gutta percha as a, 38 ----, meaning of, 279 Differential galvanometer, the, 88 Direction of current, 272 Directions for using the diving apparatus, 261 Discharge test, the, 103 Disconnector, the, 53 Diver, dressing the, 262 Divers, boots for, 261 ----, breast plate for, 260 ----, crinoline for, 261 ----, helmet for, 260 ----, ladder for, 260 Diving, 259 ---- dress, the, 260 ----, signals employed in, 263 _Dorothea_, Fulton's destruction of the, 4 Double fluid batteries, 274 ---- ----, single and, 272 Drifting torpedoes, 116 ---- ----, American extempore, 119 ---- ----, Bushnell's, 2 ---- ----, Fulton's, 5 ---- ----, Lewis's, 117 ---- ----, McEvoy's, 118 Dualin, 216 _Duba Saife_, destruction of the, 197 Duplex spar torpedo, McEvoy's, 154 ---- ----, arrangement of wires in, 155 Dutch torpedo launches, Thornycroft's, 168 ---- ----, Yarrow's, 172 Dynamite, 211 Dynamo-electric machines, methods of coupling, 254 ---- machine, Siemens' low tension, 75