275. Eccentric, _52_, 53; setting of, 53. Edison, Thomas, 310. Edison-Bell phonograph, 310. Electricity, current, 115; forms of, 113; nature of, 270; board of piano, 280. Spagnoletti disc instrument, 212. Sparking-plug, _102_. Spectacles, use of, 48. Focus, meaning of, 237; principal, 238. Foci, conjugate, 262. Force, lines of, 116. Forces, component, 345. Free wheel, _440_. Furring-up of pipes, 391. Fusee, drum.