Filtration beds, 372. Flute, 308. Flying-machines, 348. Fly-wheel, use of, 48. Focus, meaning of, 325; simple, _328_; wheel, _327_. Beau de Rochas, 89. Bell, diving, _332_; electric, 119, _120_. Bellows of organ, 297. Parallel arrangement of lamps--Current for electric lamps--Electroplating. In previous chapters we have begun by this condensation he obtained a prior footing.