Orion, Great nebula in, 40, 41, 42, 44, 46, 50, 74, 195, 242 ——, Spectrum of, 63, 64, 65 Pegasus, Nebula in, 47, 345 Perseus, A faint diffused nebulosity in, 17 ——, New star in, 356 Photosphere, The, 69 Pickering, Professor, 358 “Plane, Principal,” The, 225, 352, 379 Planetary system, The, 37, 208 Planets, 22, 26, 28 ——, Movement of, 35, 311 ——, Orbits of, 208, 298 ——, Rotation of, on their axes, 325 Platinum, 263 Pleiades, 22 ——, Nebulae in, 71 Potassium, 272 “Plane, Principal” The, 225, 352, 379 Probabilities, Theory of, 305 Radiation of sun’s heat, 82 Ramsay, Professor, 278 Ray nebulæ, 201, 211 Rigidity of the earth, 162 Ring nebula in Lyra, The, 249 Roberts, Dr. Isaac, 198 Rosse, Lord, 57, 196–201 Rowland, Prof. Henry, 273 Sagittarius, Nebula in, 105 Satellites, 37, 209 Saturn, 25, 26, 29, 220, 233 ——, Dweller in, and the Sirian, 14 ——, Ring of, 210, 220, 231, 232, 233, 234 Scheiner, Professor, 202, 204 Seismometer, The, 165 Sirian, The, and the dweller in Saturn, 14 Sirius, 215, 216 Smiths, The parable of the, 303 Solar system, 36, 207 ——, Energy of, 350 ——, Evolution of, 20, 246–260, 349 ——, Origin of, 351 Solar system, Scale of, 29, 30, 31 Spectra, Continuous, 68, 203 ——, Discontinuous, 68 Spectroscope, The, 60, 271 Spiral form in Nature, 256, 257 Spiral nebula, The great, 192, 193, 247 Spiral nebulæ, 191–206, 211, 212, 213, 220, 243, 247, 256, 257, 258, 259, 296, 345 Star-clusters, 53–60 Star, Spectrum of, 64 Stars distinguished from planets, 28, 29 Stoney, Dr. G. Johnstone, 279 Sun compared with the planets, 26, 29 ——, Corona of, 117 ——, Contraction of, 99, 373 ——, Density of, 102, 115 ——, Heat of, 75–94, 95–111, 371, 372, 373 ——, History of, 112–121, 251 ——, Nebulous part of, 121 ——, Spectrum of, 61, 62, 69, 70, 85, 273 ——, Surface of, 278 ——, Velocity of, 354 ——, Weight of, 101 Sun heat, given out in contraction, Evaluation of, 371, 372 ——, Present emission of, 373 Sunsets, The Krakatoa, 189 _Système du Monde_, 8 Thermometer for testing the heat of the earth’s interior, 129 Thomson, Prof. J. J., 316 Tides and friction, 381 Titania, 338 Umbriel, 338 Unit of heat, 80, 89 Uranus, 37, 238, 239 ——, Satellites of, 238, 338 Venus, 23, 25, 26, 29, 208, 325 Volcanoes, 158–190 Voltaire, Fable of, 14 Waves caused by Krakatoa earth quake, 179, 182, 183 -------------------------------------------------- PRINTED BY CASSELL & COMPANY, LIMITED, LA BELLE SAUVAGE, LONDON, E.C. 20.509 ------------------------------------------------------------------------