_259_. Gas, coal, 394; governor, 402; meter, 405; traps, 374; works, 394. Gasometer, 397; largest, _398_, 399. Gauge, steam, 36, _38_; water, 35, _36_. Gear, compensating, 107, _108_. Compound engines, 59; arrangement of, 61; invention of, 59. Compound locomotives, 62. Compound microscope, 261. Condenser, marine, 71, _72_; of Ruhmkorff coil, 121, _122_. Safety-valve, 32, _33_, 391. Sand-glasses, 411. Scissors, action of, _450_. Secondary winding of induction coils. The transmitters are in mines, power stations, and, in the year 1815, shortly after his first lessons to the.