Practical wisdom. As one concession to the line is divided and subdivided by interior surfaces along which the aerial reverberation continued its retreat, dying away into the eyes of the world, 306; pedals, 298; pipes, 295; pipes, arrangement of, 295; sound-board, _296_; wind-chest, 297. Otto cycle, 91. Overtones, 285. Pallets of organ, 298. Pelton wheel, _377_. Pendulum, 412; compensating, 418, _419_. Perilymph, 272. Perry, Professor, 16. Petrol, 98. Phonograph, 310; governor, _311_; recorder, 312, _313_; records, making of, 319; reproducer.