Of, 295; sound-board, _296_; wind-chest, 297. Otto cycle, 91. Overtones, 285. Pallets of organ, 297. Parallel arrangement of lamps--Current for electric lamps--Electroplating 159 Chapter X.--RAILWAY BRAKES. The Vacuum Automatic brake--The Westinghouse air-brake 187 Chapter XI.--RAILWAY SIGNALLING. The block system--Position of signals--Interlocking the signals--Locking.