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

Middle Ages, 46, 47, 474

Milton, quoted, 5

Mirror, 19

Mohammedans, 40

Moore, Dr. McFarlan, 146, 147

Morality, effect of light upon, 9

Morse code: application of, to light-signaling, 198, 199

Moses, 195

Moving-pictures, 9, 260, 261

Munich, 72