Alps Mountains, Alpenglow, i, 168; Arctic species in, xiv, 365-6, 377; chamois of, xii, 325; foehn wall, i, 105; forming of present, iii, 236, xiv, 233; Glacial Epoch, lakes from, iii, 146, xiv, 200; glaciers and snow line, iii, 59, 60, 62, 240, xiv, 55; goats of, xii, 326; hanging valleys and electric plants, xiv, 57; historical and economic importance, 240-2, 243, 244, 245, xv, 137-8; intense folding of, xiv, 36, 230; lakes, iii, 143-46; marine deposits, 235; massif of, xiv, 234; Napoleon's passage of, 244; passes of, 58, 240-1; population and industries, 241-2; railways and tunnels, 240-1; rainfall effects, 355; rivers of, 167; rock destruction by frost, 76; snowfall measurement, i, 118; solar heat at Davos, 210; thickness of strata in, xiv, 229; winds, i, 131-2, 133; youthfulness of, xiv, 96 Alsace, potash deposits, viii, 279, xiv, 67-8, 209 Altamira, Spain, cave pictures, iii, 305, xv, 114, 116, 118, 298 Alternating Currents, iv, 307, vi, 153, 154-5, vii, 361; ammeters for, vii, 166, 169-72; carbon arcs on, 208-9; circuit breakers for, 37-8, 40-1; condensers' effects, vi, 304-5; conversion to direct, 330-48; cycles, 153, 154-5; inductance, 166-7, 169 (see Inductance); lag and lead phases, vi, 167-9, 171-4, vii, 362; lighting and magnetic effects, vi, 155-7; measurement of power, 165-9, 172; Ohm's Law for, 164-5, 170; sonic waves and, v, 108; transmission of power by, vi, 159-60, 195-6; uses, common and special, 152; use in electric furnaces, vii, 305-6; use in electrotherapy, 236-7, 244, 248-9; use in traction, vi, 161-3, vii, 186, 196; use in wireless, iv, 315, vi, 163; voltage changed, 159-60 (see Transformers); voltmeters for, vii, 154-5, 161-5; wattmeters for, 172, 173, 177 Alternating Current Generators, iv, 307 (see also Alternators) Alternating Current Motors, vi, 240-63 Alternation of Generations, xiii, 160, xvi, 166 Alternators, construction, types, and uses, vi, 157-9, 196-216; operation in power plants, 357, 374; ratings, 192-4; synchronizing action, 383-4; voltages attained, 159; wireless, vii, 290-1 Altimeter, i, 72, 366 Altitude, barometric measurement of, iv, 124; barometric pressure and, i, 23, 72, 171, 303; climatic effects, xiv, 220, 223, 364-6; potential variations with, i, 144-5; pressure table, iv, 124; rock weathering in relation to, xiv, 40; sound and, i, 186-8; temperature and, 19, 20, 303 Alto-Cumulus Clouds, i, 100, 101, 103, 298 Alto-Stratus Clouds, i, 100-3 Alum, Alums, viii, 312-13; in water filtering, 320