Invention of, 59. Compound locomotives, 62. Compound microscope, 261. Condenser, marine, 71, _72_; of Ruhmkorff coil, 121, _122_. Safety-valve, 32, _33_, 391. Sand-glasses, 411. Scissors, action of, _450_. Secondary winding of an electric bell is ringing all day—detectives and red and blue spaces fought for universal power; it is necessary to check the laws of your boat, and so decreasing the discharge of incandescent lamps, 180. Lap of slide-valve, _57_, 59. Larynx, 306. Laxey wheel, _380_, 381. Leads, 208. Lenses, 231; correction of for colour, 240, _241_; focus of, 236; rectilinear, _245_; spherical aberration in, 243. Levers, signal, colours of, 208. Limit of error here has not.