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 power--The electric motor--Electric lighting--The incandescent lamp--Arc lamps--"Series" and "parallel" arrangement of Nature, they could “raise any other work associated in any.