39

Automobiles, 238

Babylon, 39

Bacteria: effect of artificial light upon, 272 _et seq._; 281, 282

Bailey, Prof. L. H., 250

Baltimore, 98

Bamboo: carbon filaments, 169

Bartholdi, 302, 303

Beacons. _See_ Lighthouses.

Beck, 186

Beecher, 72

Beeswax, 35, 51

Benzene, 106

Bible, cited on importance of artificial light, 42-44

"Bluebird, The," Maeterlinck, 9

Blue-prints, 261

Bollman, 98

Bolton, von, 132, 133

Bombs, illuminating, 182 _et seq._

Boston Light, 164, 165, 166, 177

Bowditch, production of regenerative lamp by, 78, 79

Boy Scouts, 17

Bremer, 120

Bristol University, 252

Brush, 68, 159

Building, 8

Bunsen, 81, 85, 89, 148, 149

Bureau of Mines: cited on open flames, 234; 236

Burning-glasses, 19, 20.
_See also_ Lenses.

Butylene, 106

Byzantium, 34

Caesar, 163

Canada, 254

Candle-hour, defined, 215

Candles: progress and, 7; 25, 28, 29, 30, 33;
religious uses of, 34, 35;
as a modern light-source, 36, 37;
ceremonial uses of, 38 _et seq._; 44, 48, 57, 82, 97, 222, 299, 304

Calcium, 107, 108

Carbolic acid, 106

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, 7