Over, of which he had himself patented five other devices for producing free circulation of current on, 129. Mainspring, invention of, 412. Malleus, 272. Marconi, 140, 146. Marine chronometers, 415; delicacy of, 425. Marine speed governor, 71. Marine turbine, advantages of, 84. Maudslay, Henry, 363. Maxim, Sir Hiram, 348. Micrometer free wheel, 441. Micro-photography, 265. Microscope, 254; compound, 261, _263_; in telescope, 257; simple, _254_. Mineral oil, 392. Mirror, parabolic, 261, _262_; plane, _267_. Morse, 132, 145; code, 128; inker, 142; sounder, 132. Telegraphy, high-speed, 135; wireless, 137. Telephone, 147; Bell, _148_; circuit.