Ocean and land, diagram of, 228. ---- basins, permanence of, 229. ---- ---- symmetry of, 238. ---- depths, how produced, 232. Oceans, effect of, on temperature, 239; curious relations of, 264. Organic products, diversity of, 195. Photographic astronomy, 43; measures of star-distances, 89. Photosphere, the, 105. Physicists on sun's duration, 278. Pickering's measurements of Algol, 40. Planets, supposed habitability of, 266, 269; the great, uninhabitable, 272; internal heat of great, 273; a last argument for habitability of, 274; have probably no life, 315. Planets' motions first explained, 3; mass and atmosphere, 262. Pleiades, number of stars in, 67; a drifting cluster, 177. Plurality of worlds, early writers on, 9; Proctor on, 18. Posidonius measures the earth, 5. Pritchard's photographic measures of star-distance, 89. Proctor, R.A., on other worlds, 18; on form of Galaxy, 51; on Herschel's views, 101; on stellar universe, 103; on meteoritic theory, 114; on infinities, 136; on star-drift, 176; on life under varied conditions, 271; on infinity, 324. Proctor's _Old and New Astronomy_, 46; chart of stars, 60. Prominences of sun, 107. Proteids, formation of, 199; Prof. Haliburton on, 200. Protoplasm, complexity of, 194; a mechanism, 198; sensibility of, to heat, 208. Ptolemaic system of the heavens, 4. Radial motion, 35. Radiation from stars, 290. Rain in the Carboniferous age, 225; dependent on dust, 249. Ramsay, Prof., on geological climates, 278. Ranyard, on star-discs, 98; on infinite universe, 137; on mass of Orion nebula, 173. Religious bearing of my conclusions, 319. Reproduction, marvel of, 201. Reversing layer of sun, 107. Roberts, A.W., on birth of double stars, 123. ---- Dr. I., on limits of star-system, 148; on spiral nebulæ, 117; on meteoritic theory, 119; photographs of nebulæ, 45, 174. Roche limit explained, 120, 187. Sanderson, Prof. Burdon, on living matter, 192. Scientific and agnostic opinion on my conclusions, 318. Secchi's classification of stars, 33. Single stars perhaps rare, 128. Solar apex, position of, 176. Solar cluster, the, 165; diagram showing, 300; evidence for, 302; importance to us, 306-7, 312. Solar system, position of, 304. Sorby on constitution of meteorites, 186. Spectra, varieties of, 34; of elements, changes in, 129. Spectroscopic binaries, abundance of, 125; great numbers of, 286. Spectrum analysis, discovery of, 26. Spencer, H., on status of nebulæ, 102. Spiral nebulæ, origin of, 120.