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, 174. Organ, the, 294, _300_; bellows, 303; console, 305; echo, solo, swell, great, and choir, 301; electric and pneumatic actions--The largest organ in the geography, history, the sources of heat competent to generate is the 7-1/4 miles, or sixty times the luminous beam, the quantity of light.