coal as, source, 55;
  early uses of gas as, source, 63 et seq.;
  as a public utility, 70;
  first installation of industrial gas, 72;
  science of, production, 80 et seq.;
  causes of, radiation, 80, 81; 83;
  lime, 84; electric, 89 et seq.;
  principle of, production, 90, 91;
  sources, 93;
  various gas-burners’, supply, 95;
  relative efficiency of, sources, 95, 96;
  in the home, 97;
  influence of, upon science, invention, and commerce, 97 et seq.;
  yield of acetylene, 106, 107;
  electric, 109;
  influence of gas upon development of artificial, 110;
  development of artificial, 111 et seq.;
  efforts to improve color of mercury-arc, 125;
  electric-incandescent-filament, 127 et seq.;
  effect of tungsten, upon, 133 et seq.;
  of the future, 143-152;
  in warfare, 178-193;
  signaling, 194-207;
  cost of, 208-224;
  and safety, 225 et seq.;
  improper use of, 229, 230;
  comparison of daylight and artificial, 240;
  reducing action of, 258;
  bactericidal action of, 272 et seq.;
  modifying, 284 et seq.;
  spectacular uses of, 298-309;
  expressiveness of, 310-324;
  utility of modern, 325-340;
  evolution of the art of applying, 341-356;
  mobile, 347, 348, 349, 350;
  psychological effect of, 351 et seq.;
  as an accompaniment to music, 352-354

Light-buoys, 10, 169

Lighthouses:  10, 163-177;
  optical apparatus of, 172 et seq.

Light-ships, 10, 169

Lighting-systems:  comparison of, 12-14

Lime, 84, 107, 108, 294

Lincoln, Abraham, 9

Linen, 18

Link-buoys, 28

Lithopone, 265, 266

Liverpool, 167

Living:  comparison of, standards, 238 et seq.

London, 152, 154, 155, 156, 157, 202

London Gas Light and Coke Company, 74

Lucigen, 61

Lumen-hour:  defined, 215

Lumens:  60, 94, 215

Lutheran Church, 49

Lyceum Theatre, London, 73

Maeterlinck, Maurice, 9

Magazines, 8

Magdsick, H. H., 303

Magnesia:  84;
  Nernst’s application of, 138

Magnesium, 179, 180

Magnetite arc, 187

Man:  distinction between, and animal, 3;
  artificial light and early, 4;
  light-sources of primitive, 25

Manganese, 262, 268, 294

Mangin, 188

Mann, 129

Mantles, 95

Manufacturing, 8

Marconi, 68

Marks, 118

Matches:  as light-sources, 21; 22, 82

Maxwell, 68

Mazda lamps, 289, 339

Mecca, 40

Mediterranean Sea, 163

Mercury-arc:  Way’s, 124; 125, 126;
  quartz, 125, 126;
  attempts to improve color of, light, 125