Force, and induced currents, 101; lines of magnetic, 38; lines of about a wire, 92, 96; lines of about a magnet, 37, 38. Frictional electricity, about, Chap, I.; location of charge of, 4; sparks from, 4. Fuller cell, the, 55. Fuse, link, 142; plug, 142; ribbons, 142; wire, 142. Fusible rosettes, 142. Galvani, early experiments of, 44. Galvanometers, 73; astatic, 73; considered as motor, 161; D'Arsonval, 73; tangent, 73. Galvanoscope, 73; astatic, 94. Gas lighters, electric, 174. Geissler tubes, 156. Generators, electric, 126. Glass, electricity generated upon, 4. Glue pots, electric, 147. Gold-leaf, for electroscopes, 5. Gold plating, 82. Gonda cell, 57. Gong, electro-mechanical, 116. Gravity cell, the, 56; replaced by dynamotors, 137. Grenet cell, 52. Griddles, electric, 147. Guard, for lamps, 151. Heat, how generated by electricity, Chap. X.; and magnetism, 35; and resistance, 145. Heat lightning, 19. Heaters, for cars, 167. History of electricity, 3. Horse-power, electrical, 77. Horseshoe, permanent magnets, 26; electromagnets, 97, 98. Human body, bones of, photographed by x-rays, Chap. XXIII. Hydrogen, action of in cell, 48; attraction of for oxygen, 85. Incandescence, 148. Incandescent lamp, 149; candle-power of, 150; current for, 150; light produced by, Chap. XXI.; construction of, 149; uses of, 151. Inclination of magnetic needle, 42. Indicating push-button, 61. Induced currents, 127; and lines of force, 101; by rotary motion, 128; of induction coils, 105; of transformers, 135. Induced magnetism, 36. Induction, electricity generated by, Chap. XII.; electromagnetic, 99. Induction coils, condensers for, 104; construction of, 104; currents of, 105; how they work, Chap. XIII.; in telephone work, 124; uses of, 106. Inductive influence of earth, 43. Influence machines for medical purposes, 13. Ink writing registers, 114. Insulating tubing, 141. Insulators, 141; and conductors, 4, 138; feeder-wire, 167; for poles, 167; porcelain, 141. Internal resistance, 68. Interrupters, automatic current, 104, 115. Ions, 80. Iron, electricity upon, by friction, 4. Jar, Leyden, 15. Jarring magnets, effects of, 33. Keeper of magnets, 26. Keys, telegraph, 109. Kinds of electrification, 6. Kitchen, electric, 147. Knife switch, 62.