First practical typewriter--C. L. Sholes, United States, 1861. Railway air-brake, use of air-pressure in applying brakes to the wheels of a car. A strong spring presses the brake against the wheels. Air acts against the spring and holds the brake away from the wheels. To apply the brake, air is allowed to escape, reducing the pressure and allowing the spring to act--George Westinghouse, United States, 1869. Store-cash carrier--Dr. Brown, United States, 1875. Roller flour-mills--F. Wegman, United States, 1875. Kinetoscope, moving-picture machine--Edison, 1893. INDEX Aeroplane, 184. Air-pressure, 23. Air-pump, 20. Air-ships, 173. Air thermometer, 13. Alternating current, wonders of, 225. Amber, 8. Ampère, 67, 111. Arago, 69. Archimedes, 1, 12; inventions of, 7. Archimedes' principle, 6, 12. Arc light, 120. Armature, 101, 103, 104. Balloons, 174. Barometer, mercury, 19, 25; water, 23. Battle of Syracuse, 2. Bell, Alexander Graham, 141. Blake transmitter, 146. Blériot, 190. Boyle, 23. Branly, 214. Cannon experiment, Rumford's, 59. Cog-wheels, first used, 8. Coherer, 214. Colors in sunlight, 31. Condenser in steam-engine, 40. Conductors, electrical, 44. Controller, 116. Daniell cell, 89, 127. Davy, 56, 61, 96. De Forest, 224. Diamonds, manufacturing, 206. Drum armature, 104. Dry battery, 91. DuFay, 45. Dumont, 179. Duplex telegraphy, 136. Dynamo, 55, 79, 81, 96, 99, 100, 105, 111; series wound, 105; shunt wound, 107; compound wound, 108. Edison, 95, 105, 114, 121. Electrical machine, 23, 44, 45, 83. Electric battery, 53, 62, 84, 89. Electric charge, two kinds, 45. Electric current, 50, 69, 73, 74, 82, 96; magnetic action of, 66, 68; produced by a magnet, 72. Electric furnace, 205. Electricity, 8, 50; theories of, 49; speed of, 133. Electric lighting, 97, 118. Electric motor, 71, 97, 111. Electric power, 111. Electric railway, 112. Electric waves, 212. Electromagnet, 100, 126, 143. Electromagnetism, 65. Faraday, 55, 63, 100, 111; electrical discoveries, 64. Force-pump, 8. Franklin, 43, 45, 46, 65. Galileo, 9, 63; experiment with falling shot, 12. Galvani, 50. Galvanometer, 74, 75. Gas-engines, 150. Glider, 186. Governor, fly-ball, 42. Gramme-ring armature, 103. Gravitation, 30. Gravity cell, 91. Gray, Stephen, 44. Guericke, 20, 35. Gyroscope, 200. Heat, 59. Henry, Joseph, 97, 127. Hero, 8, 164; engine, 164. Hiero, King of Syracuse, 1, 6. Horse-power, 40. Hydraulic press, 26. Incandescent light, 121. Indicator, 41.