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, 315; tracings on record of, _317_. Pianoforte, 277; sounding-board, 280; striking mechanism, 281; strings, 281. Piccolo, 308. Pipes, closed, 289; flue, 301; open, 292; organ, 295; reed, 301, _302_; tuning, 302. Piston valve, 67. Pneumatic tyres, 341. Poldhu, signalling station at, 138. Points, railway, 208, _210_; and signals on double lines of force, 116, 162. "Linking up," 65. Locks, 430; Barron, 433; Bramah, 437; Chubb, 433, 434; Hobbs, 437; simplest, _431_; tumbler, _432_; Yale, _436_. Locking gear for signals, 205. Locomotive, electric, 178; advantages of, 84. Maudslay, Henry.