Resistance bridge, 7. Resistance, external, 37. Resistance, internal, 37. Rheostat, 7. Reversed, 20, 50, 153. Reversible, 163. Reversing, 176. Reversing switch, 67. Revolubly, 46. Revolve, 179. Revolving, 177. Roentgen rays, 184. Roentgen tube, 187. Rotation, 149. Rubber, 40, 46, 77, 115, 126, 130, 138. S Sad-irons, 13. Saline, 133. Sanitation, 12. Saturated, 85. Screw, 15. Screw, binding, 65, 66. Screw-driver, 14. Screw, set, 72. Sealing wax, 53. Secondary, 62, 98, 105, 158, 159, 160. Secondary circuit, 99. Secondary coil, 107, 108. Self-induction, 149, 156. Sender, 90, 97. Sending apparatus, 106. Sending key, 90. Separately excited, 46. Series-wound, 47. Severed magnet, 20. Sewage, 12. Shaft, 30. Shears, 14, 17. Shellac, 40. Shunt-wound, 47. Signal, 118. Silver, 19, 63, 125. Silver nitrate, 62. Socket, 54, 139. Soldering, 14. Soldering iron, 17. Solution, 55, 57, 62, 63, 84, 86, 133, 134, 142. Sounder, 90, 92, 95, 96. Sounding board, 119. Source, charging, 83. South pole, 20, 21, 22, 25, 50, 54, 156. Spark gap, 102, 106. Spark jump, 99. Spring finger, 69. Square, 14, 17. Standard, 62, 63. Station, 94, 95, 117, 122. Steel, 18, 19. Steel magnet, 53. Sterilized, 12. Stirrup, 75. Stock bit, 13. Stock contact, 121. Storage, 82. Storage battery, 107. Storing, 82. Substances, 135. Sulphate, 55, 128, 133. Sulphur, 19. Sulphuric acid, 31, 84. Sulphuric acid voltameter, 55, 57. Superstition, 171, 173. Surging, 153, 154. Swinging magnet, 53. Swinging switch blade, 67. Switch blades, 66. Switches, 65, 66, 70, 77, 78, 90, 117. Switches, bar, 65, 68, 90, 91. Switches, bar, parallel, 67. Switches, heart-shaped, 78. Switches, piece, 77. Switches, reversing, 67. Switches, sliding, 67, 80. Switches, terminal, 8. Switches, two-pole, 65. System, circuiting, 79. T Tail-piece, 16. Tantalum, 169. Telegraph, 11, 90, 96. Telegraph key, 106. Telegraph sounder, 108, 109. Telegraphing, 94. Telephone, 12, 110, 113, 117, 118, 119, 120. Telephone circuit, 118. Telephone connections, 116. Telephone hook, 122. Temperature, 56, 88, 134, 161, 170. Tension, high, 38, 102, 184. Tension, low, 38, 98, 102, 179. Terminal, 31, 34, 35, 40, 48, 82, 86, 93, 95, 107, 116, 121, 122, 151, 152, 153, 154, 156. Terminal knob, 31. Terminal, secondary, 102. Terminal switch, 81. Theoretical, 160. Therapeutics, 187. Thermo-electric couples, 146. Thermo-electricity, 135. Thermometer, 56. Thorium, 169, 186. Thunderbolt, 171, 173. Tin, 136. Tinfoil, 31, 101. Tools, 11, 13, 17. Torch, brazing, 17. Transformer, 145, 146, 158, 159, 180, 182. Transformer, step-down, 182. Transmission, 38, 187. Transmit, 63, 95, 157. Transmitter, 12, 120, 121, 122, 123. Transverse, 16, 52. Transversely, 43. Trigger, 75. Tripod, 31. Tubular, 44, 45. Two-pole switch, 65. U Ultra-violet, 185. Uranium, 186. V Vacuum, 184. Vapor lamps, 169. Velocity, 60, 73. Vertical armature, 75.