INDEX.

signalling, 228; stoker, 399. Backfall, 298. Balance-wheel, 419. Ball cock, 366, 367 . Balloon, fire, 323; gas, 347. Barometer, aneroid, 328, 329 ; and weather, 331; Fortin's, 326 ; meaning of, 325; simple, 328 ; wheel, 327 . Beau de Rochas, 89. Bell, diving, 332 ; electric, 119, 120 . Bellows of organ, 303. Bioscope, 266. Blades, turbine, 81 , 83. Block system, 201, 212. Blood, arterial, 359; circulation of, 356 , 357 , 360; venous, 359. Blower-plate, 393, 394 . Boat, sails of, 346. Boiler, Babcock and Wilcox, 21 , 22;