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 Murdock, William: installment of gas-pipes by, 63; 68, 69, 70; quoted on industrial use of artificial, 71; 72, 73, 74, 76, 78, 217, 309 Museums: 13; utilization of artificial light by, 322, 323 Music: light as an accompaniment to, 352-354 Mythology, 16 Nantes, 85 Napoleon, 111 Napthalene, 106 National Heat and Light Co., 72, 74 Natural gas, 99 Navesink Light, 206 Nernst, 138, 139 Newspapers, 8 Newton, Sir Isaac: 7; quoted on discovery of visible spectrum, 87; 88 New York, 98, 165, 166, 206, 302, 304 Niagara Falls, 108, 306 Nickel, 262 Nielson, 77 Niepce, 258 Niter, 21 Nitrogen, 137 Norfolk, 169 Obesity, 275 Offices, 13 Oil: as a light-source, 29 _et seq._; development of, lamps, 51 _et seq._; 155; in lighthouse, 165 _et seq._; 222, 224, 299 O'Leary, Mrs., and her lamp, 62 Olive-oil, 51, 52, 167 Orkney Islands, 29, 177 Osmium, 133 Oxygen: relative consumption of, by oil-lamps, 58, 59; 262 Ozone, 262 Painting, 342, 343, 347, 348, 349 Pall Mall, 74 Panama-Pacific Exposition: 304; artificial lighting of, 306, 307, 308, 309 Paper: 18; carbon filaments, 129, 130 Paraffin, 35, 57 Parker and Clark, 139