Diagrams of star-distribution, 62, 66. Diffraction-gratings, 30. Disruption of stellar bodies, 187. Doppler principle, the, 37. Double stars, evolution of, 123; not fitted for life, 286. Dust, importance of, 249. Dust-free air, results of, 254. Earth, first measured, 5; in relation to life, 218; the only habitable planet, 262; cannot retain hydrogen, 264; supposed extreme conditions of, 271. Earth's mass, how related to life, 265. Ecliptic, obliquity of, in relation to life, 219. Electricity, effects of atmospheric, 257; atmospheric, how caused, 258. Elements, change in spectra of, 129; in the sun, 184; in meteorites, 185; in organic structures, 201. Empedocles an early astronomer, 3. Eudoxus on motions of planets, 3. Evolution of the stars, 128. Explanations of life-processes, 202. Faculæ of sun, 105. Fisher, Rev. O., on oceanic basins, 234; on thin sub-oceanic crust, 237. Fizeau measures speed of light, 79. Flammarion, C., on universality of life, 274, 281. Fontenelle on plurality of worlds, 9. Galileo on star measurement, 74. Geological climates, 222. Geologists on duration of sun's heat, 275. Germinal vesicle, M'Kendrick on, 202. Gill, Sir D., on systematic star-motions, 178. Globular clusters, stability of, 126; and variables, 127. Gore, Mr. J.E., on stars in Galaxy, 60; on mass of binary stars, 97; on remoteness of bright stars, 140; on limits of star system, 145; on limited number of stars, 151; on life on planets of other suns, 282, 289. Gould on solar cluster, 165. Gould's map of Milky Way, 164. Gravitation, motions produced by, on Lord Kelvin's hypothesis, 298. Haliburton, Professor W.D., on proteids, 200. Heat and cold on earth's surface, 207. Heat-supply, our long-continued, accounted for, 305. Herschel, Sir J., on Milky Way, 50; on limits of the star-system, 147. Heliometer, description of, 89. Huggins, Sir W., on spectra of stars, 32; measures radial motion, 37. Huxley, Prof., on protoplasm, 198; on duration of life, 278. Hydrogen, why not in atmosphere, 240; escapes from earth, 264. Infinity, unknowable, 323; Proctor on, 324. Jupiter's satellites show speed of light, 79. Kapteyn on solar cluster, 166. Kelvin, Lord, on the sun's age, 279; on a suggested primitive form of star-system, 298. Kirchhoff, discovers spectrum-analysis, 28. Laws of matter uniform throughout universe, 187. Leaves, importance of, 197. Lee, Dr., on origin of double stars, 123. Lewis, on remote bright stars, 141.