Carbon: 53, 80, 81; physical characteristics of, 80, 81; 90, 104, 105, 128, 129, 144, 170 Carbon filament: 127 _et seq._; preparation of, 129, 130, 131; luminous efficiency of, 131, 132; lamps, 161; lamps in greenhouses, 250 _et seq._ Carbons, formation of, 115, 116 Carbureted hydrogen, 75 Carcel, invention of clockwork lamp by, 54, 55 Cat-gut, 130 Ceria, 85, 101 Charleston, S. C., 185 Charcoal: 113; uses of, for electrodes, 115 Chartered Gas Light and Coke Co., London, 74 Chemistry: artificial light and, 256-268 Chicago, 62, 304, 305 Chimneys, 54, 60, 62 China, 19, 31, 32 Chlorate of potash, 22 Christ, 33, 46, 47 Christians, "children of light," 42 Christmas trees, 43, 304 Chromium, 294 Church of England, 49 Cities: economy of artificial lighting in congested, 13 Civilization: effect of artificial light upon, 4 _et seq._; fire and, 15 Clark, Parker and, 139 Clayton, Dr.: invention of portable gas-light by, 64; quoted, 64, 65; experiments of, with coal-gas, 67 Claude, 147 Cleaves, Dr., quoted, 276, 277 Clegg, Samuel: 74; gas-lighting accomplishments of, 75, 76 Cleveland, 159 "Clouds, The," Aristophanes, 19 Coal: 32; as a light-source, 55; supply, 223; 228 Coal-gas: 63 _et seq._; public lighting by, developed, 70 _et seq._; analytical production of, 103, 104; yield of, retort (table), 105; analysis of, 106 Coal-mines, 234 _et seq._ Cobalt, 294 Coke, 68, 105 Cologne, 157, 158 Colomb, Philip, 197 Color: 9; relation of artificial light to, 284 _et seq._ Colza, 31, 52, 167 Combustion, 82 _et seq._ Commerce, 8, 97 Constantine, 42 Copper, 262, 295 Cornwall, 63 Cotton: 101; carbon filaments, 129, 130 Cromartie, 78 Crookes, 90, 146 Crosley, Samuel, improvement of gas-meter by, 76 Crusies, 32 Daguerre, 258 Dancing, 346 Davy, Sir Humphrey: 33, 68, 73; first use by, of charcoal for sparking points, 112; notes of, on electric arc, 113; 114 Daylight, artificial, 12: 284 _et seq._; application of, 287 Daylighting, 12-14 Dollond, 195 Doty, 61, 167 Drake, Col. E. L., discovery of oil in Pennsylvania by, 56 Drummond, Thomas: 171, 185, 196; quoted on signaling, 197 Dudgeon, Miss, 251, 252 Dyes, 256, 265 East Indies, 29 Eddystone Light, 166, 167 Edison: and problem of electric incandescent filament lamps, 128 _et seq._; 129; quoted on birth of incandescent lamp, 130 Edward I, 274 Edward VI, 49 Efficiency, effect of artificial light upon, 14 Eggs: relation of artificial light to production of, 247, 248 Egypt: 31; sacredness of light in ancient, 39; 153, 195 Electric filament: 81, 127 _et seq._: approximate value of, lamps (table), 138 Electric pile: construction of, 111; 127 Electricity: 13, 22; as a light-source, 57; for home-lighting, 62, 84; 87, 89; ignition of gas by, 102; lighting by, 109 _et seq._ Electromagnetic waves, 68, 86, 87 Electromagnets, 114, 116 Electrodes, 113, 114, 115 _et seq._; life of, 122