Bernoulli, 221, 341 Beta Persei, 308 Biela's comet, 296-7 Binary compound, 143 stars, 25, 309 Biot, 138 Boscovitch atoms, 44, 138 Boyle and Marriotte's law, 76, 103 Bradley's discovery of aberration, 149 Bredichin on comets' tails, 302 Brilliancy of stars, 307, 309 British Association Report, 57, 59 Calcium, 79 Canis major, 307 minor, 307 Capella, 312 Carbon, 48 Carboniferous period, 115 Carnot on heat, 116-18 Cassini, 307 Cause and effect, 14 of gravitation, 1, 282-9 Cavendish experiment, 24 Centauri, 79 Centre of gravity, 325 Centrifugal force, 9, 13, 15, 30, 236-8 Centripetal force, 9, 12, 282 Cetus, 307 Chalk, 6 Challis, Prof., 74, 96, 100, 107, 151, 155, 214, 227, 311 Chemistry, 47, 336 Coal, 86, 88 Clairaut, 297 Clusters of stars, 314 Cohesion, 48 Colour, 138 Colours of stars, 308 seven primary, 139 Comets, 291 attracted by planets, 298 condensation of, 292 Comets and meteors, 297 short period, 293-4 long period, 293-4 tails of, 298-9 orbits of, 293 nucleus of, 298-9 coma, 298-9 Compressibility of aether, 291, 315 Condensation of gases, 47 Conservation of matter, 42 of energy, 84 of motion, 92 Constellations, 307 Corollary, 15 Corona Borealis, 309 Corpuscles, 42, 64, 136 Corpuscular theory of light, 122 Correlation of forces, 83 Coulomb Torsion balance, 185, 187 Crookes, Sir William, 42, 136, 326, 341 Current, electric, 163 magnetic, 192 Currents, 90 Curry, Prof., 284 Cycle of operations, 114, 116 Cygnus, 307 Dalton's atomic theory, 42 Davy, 99, 107 Day and night, 4 D'Arrest's comet, 296 Deimos, 38 Democritus, 44 Density of matter, 51 of aether, 69 electric, 170 of earth, 242 of sun, 27 of planets, 242 Descartes, 221-2, 341 Dewar, Prof., 47 Diameter of earth, 29 polar, 29 equatorial, 29 of sun, 280 of planets, 29 Dielectric, 168, 175 Diffusion, 49 Dip, magnetic, 199 Distances of stars, 280 Diurnal variations, magnetic, 209 Dog star (Sirius), 306 Donati's comet, 298 Double stars, 308 Draco, 307 Dynamical equivalent of heat, 114 value of light, 150 Dynamics, laws of thermo-, 114-18 Dynamo, 87, 90 Ear, 120 Earth, mass of, 235, 242 a magnet, 196-8 size of, 29 rotation of, 219 orbit of, 276 periodic time of, 251 gravity of, 29 shape of, 29 distance from sun, 242, 251 velocity in orbit, 251 Eccentricity of orbits, 268, 276 Eclipse, 145, 148 Ecliptic, plane of, 277-9 Elasticity, 46 of matter, 51 of aether, 74 Electric current, 154 potential, 170 induction, 175 radiation, 182 density, 170 energy, 179 field, 166, 179 lines of force, 173 Electricity, 64, 162 two kinds of, 175 positive, 175 negative, 175 laws of, 184 theories of, 162 Electrons, 136, 163 Electro-static, 158, 164 kinetic, 158, 164 kinetic energy, 217 magnetism, 192-5 magnets, 199 magnetic theory of light, 229 chemical equivalents, 189, 333 Elements of matter, 47