Niagara Falls Power, Chs. XXII to XXVIII, 186 to 233. Introduction--rock, water, power, 186. Appliances: tunnel, power-house, 190. shaft, dynamos, 192. current, 193. governor, 194. water-head, 195. crane, 196. circuit-breaker, 199. transformer, 200. electromotive force, 204. Electrical Products--Carborundum, 209. materials, 210. furnaces, 211. electric current, 213. horse-power, 214. method of work, 215. Bleaching-powder, 218. chlorine and sodium, 219. method of work, 220. caustic soda, 221. Aluminum, 223. crucibles and methods, 224. magnetic effects, 226. Calcium carbide, 228. process, 229. acetylene gas, 230. Other products, 232. Oersted, galvanic current on magnetic needle, 93. Ohm, G. S., resistance unit, 74. Patents--Caveat and application, 135. Plante, storage-battery plates, 64. Pliny mentions electrical properties of amber, 67. loadstone, 20. Preece, double transmission, 114. Prescott, Geo. B., quoted, 104, 106, 163, 174. Ptolemy Philadelphus and loadstones, 20. Pythagoras refers to natural magnets, 20. Radiophone, 171. Railway train telegraphy, 131. Richman, Prof., killed, 12. Reiss, metallic telephone transmitters, 122. Resistance, unit of, 74. -coil, 118. Siemens, double transmission, 114. Selenium in radiophone, 172. Shephard, Charles S., induction-coil, 122. Stager, Gen. Anson, telegrapher, 110. Stearns, Joseph B., cures the "kick" in double transmission, 115. Storage-battery, 24. Strada, loadstone telegraph, 88. Submarine cables, Ch. XVII, 154. first lines, 154-5. Maury's deep-sea soundings, 155. first Atlantic, 156. retardations, 157. receiver, 158. Sun-spots and magnetic storms, 37. Telautograph, Ch. XIX, 165. Telegraph: heliostat, 68. semaphore, 68. loadstone, 88. Franklin's electric firing, 88. electrically dropped balls, 88. electric transmission of musical tones, 91. of signals, 94. Morse register, 95. first line, 97. description, 98. reading by various senses, 100. Bain, chemical recorder, 101. Cooke needle, 108. Wheatstone needle, 108. House printing, 108, 110. Hughes printing, 108, 112. automatic systems, 109, 112. multiple transmission, 114. musical transmission, 120. musical receivers, 125. Way duplex, 129. from moving railway trains, 131. repeater, 150. short-line dials, 159. printing, 163. wireless, Ch. XXI, 176. Telegraphic messages, receiving, 103.