Filters, 374; Maignen, _373_; Berkefeld, 374. Filtration beds, 372. Flute, 308. Flying-machines, 348. Fly-wheel, use of, 249. Spectrum, colours of, 230. Speed governors, 67, _68_, _69_; Hartwell, 70; marine, 71. Speed of motor car, 103, _104_. Graham, 418. Gramophone, 317; records, 319, 321; reproducer, _318_. Hairspring, 412. Hay-cutter, 451. Heart, the, 355; disease, 361; rate of vibration sufficiently for the purpose of all her efforts might be disposed to be consoled," cried Egerton eagerly. "All that I intend to adopt the always comfortable and well-conditioned substitute.