_139_. Yale lock, 436. Combustion, 26, 393; perfect, 28. Compensating gear, 107, _108_. Gear-box of motor car, 105. Coal, as fuel, 15; gas, 394; gas plant, _396_; gas, purification of, 397. Cochlea, 273. Coherer, 140. Coil, Ruhmkorff, 121. Coke, 395. Combinations in Chubb lock, 435. Diving-bell, _332_; simple, _333_, _334_. Diving-dress, 335. Direction of current on, 129. Mainspring, invention of, 412. Malleus, 272. Marconi, 140, 146. Marine chronometers, 415; delicacy of, 425. Marine speed governor, 71. Marine turbine.