Erg-seconds, 179 Essential characteristics, 142 Euclidean geometry, 159 Events, location of, 41; point-events, 49 Evolution, irreversibility of, 91; in stellar system, 167, 176 Exact science, 250 Existence, 286 Experience, 288, 328 Explanation, scientific ideal of, xiii, 138, 209, 248 Extensive abstraction, method of, 249 External world, 284 [Pg 357] Familiar and scientific worlds, xiii, 247, 324 Fictitious lengths, 19 Field, 153 Field-physics, 236 Finite but unbounded space, 80, 139, 166, 289 FitzGerald contraction, 5, 24; reality of, 32, 53 Flat world, 118, 138 Flatness of galaxy, 164 Force, 124 Formality of taking place, 68 Fortuitous concourse of atoms, 77, 251 Fourth dimension, 52, 231 Fowler, R. H., 204 Frames of space and time, 14, 20, 35, 61, 112, 155 Freak (solar system), 176 Freewill, 295 Fullness of space, measures of, 153 Future, relative and absolute, 48; see Predictability Future life, 351 Future perfect tense, 307 Galactic system, 163 Geloeology, 335 General theory of relativity, 111, 129 Generation of Waves by Wind, 316 Geodesic, 125 Geometrisation of physics, 136 Geometry, 133, 157, 161 Grain of the world, 48, 55, 56, 90 Gravitation, relative and absolute features, 114; as curvature, 118; law of, 120, 139; explanation of, 138, 145 Greenland, 117 Gross appliances, survey with, 154 Growth, idea of, 87 Group velocity, 213 , 179, 183, 223 Halo of reality, 282, 285, 290 Hamilton, W. R., 181 Hamiltonian differentiation, 240 Heaven, 351 Hegel, 147 Heisenberg, W., 206, 220, 228, 306 Heredity, 250 Here-Now, 41 Heterodyning, 216 Hour-glass figures, 48 House that Jack Built, 262 Hubble, E. P., 167 Humour, 322, 335 Humpty Dumpty, 64 Huxley, T. H., 173 Hydrodynamics, 242, 316 Hydrogen, 3 Hyperbolic geometry, 136 Hypersphere, 81, 157 (square root of -1), 135, 146, 208 Identical laws, 237 Identity replacing causation, 156 Illusion, 320 Impossibility and improbability, 75 Impressionist scheme of physics, 103 Indeterminacy, principle of, 220, 306 Inertia, 124 Inference, chain of, 270, 298 Infinity, 80 Infra-red photography, 173 Inner Light, 327 Insight, 89, 91, 268, 277, 311, 339 Instants, world-wide, 43 Integers, 220, 246 Interval, 37, 261 Intimate and symbolic knowledge, 321 Introspection, 321 Invariants, 23 Inventory method, 103, 106, 280, 341 [Pg 358] Inverse-square law, 29 Island universes, 165 Isotropic directed curvature, 144 Jabberwocky, 291 Jeans, J. H., 176, 187 Johnson, Dr., 326 Jordan, P., 208 Knowable to mind, 264 Knowledge, nature of physical, 257, 304; complete, 226 Laplace, 176 Laputans, 341 Larmor, J., 7 Laws of Nature, 237, 244 Laws of thought, 345 Lenard, P., 130