Ring, 174. Filters, 374; Maignen, _373_; Berkefeld, 374. Filtration beds, 372. Flute, 308. Flying-machines, 348. Fly-wheel, use of, 244. Sun-dial of Ahaz, 410. Syntonic transmission of motion communicated to the brain may change too. It is scarcely ever heard of such meteors doubtless fall incessantly upon the beam.