INDEX

Aberration of light, 69, 149, 218 Absorption, 104-6 Acceleration, 239 Actinic rays, 141 Action at a distance, 96, 174, 176 and re-action, 20, 251 Adams' discovery of Neptune, 25 Aether is matter, 54-8 is atomic, 59-67 is gravitative, 64-9 density of, 69, 71, 136, 243 elasticity of, 74-7 inertia of, 76, 330 its motions, 80 compressibility of, 291, 315 waves, 79-80 Aetherial basis of matter, 326 Affinity, chemical, 43 Aldebaran, 312 Aluminium, 79 Ampère, 192 Ampère's theory of magnetism, 193 Andromeda, 314 Annual magnetic variation, 208 Annular nebulae, 320 Aphelion of earth, 36 Arago, M., 321 Arcturus, 312 Areas, Kepler's law of, 36 Asten, Von, 234, 296 Asteroids, 31 Atmosphere, 68, 73, 102, 225 Atom, vortex, 45, 46, 61 what it is, 43 electron, 63 Boscovitch, 61 hard, 61 size of, 43 Attraction, electrical, 2, 286 of gravitation, 13, 24, 31 magnetic, 195 Balance, Torsion, 187 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 Ellipse, 34 Kepler's discovery of, 34 Elliptical nebulae, 320 Emission theory of light, 122 Encke's comet, 293, 296 resisting medium, 228 Energy, 83, 84 what it is, 83 conservation of, 84 transformation of, 86 potential, 87 kinetic, 89, 164 radiant, 109 electrical, 179 and motion, 91 Engine, Carnot's heat, 116 Envelopes of comets, 298 Epicureans, 44 Equal areas, 36 times, 36 Equator, N. and S. Poles, 29 magnetic, 202 terrestrial, 29 Equipotential surfaces, 171 Equivalents, electro-chemical, 189, 333 Euler, 123 Exchanges, theory of, 105 Experience, 4 Experiments of Rumford, 98 of Michelson and Morley, 67, 227 of Lebedew, 302 of Nichols and Hull, 153 of Hertz, 165 of Faraday, 65, 285 of M. Faye, 302 of Joule, 114 Falling stone, 21, 29 Faraday, 45, 175, 220 on matter, 56 on Lines of Force, 168, 200, 203-5 on magnetic space, 208 on gravitation, 287 on electricity, 332 on induction, 176 Faye, M., 111, 302, 319 Faye's comet, 293, 296 Field, electric, 179 magnetic, 199 Fizeau, 149, 224 Fluids, 48 Food, 89 Forbes, 121 Force, 16, 19, 90 centrifugal, 9, 13, 236 centripetal, 9, 12, 282 lines of, 200 Forces, direction of the, 26 proportion of the, 26 Foucault, 149 Franklin, 106 Fresnel, 75, 131 Frictionless medium, 17, 131, 136, 224 Fundamental medium, 54 Galaxy, 325, 346 Gaseous nebulae, 313 Gases, condensation of, 47 liquefaction of, 47 kinetic theory of, 49 Glazebrook, Prof., on aether and gravitation, 22 Globular clusters of stars, 314 Gravitation, law of, 61, 65 universal, 24 intensity of, 27 law of proportion, 26 cause of, 1, 282 and binary stars, 25 Gravity, centre of, 325 Great Bear, 307 Grove, 83 Halley's comet, 296-7 Hamilton, Sir W. R., 247 Head of comets, 298 Heat is motion, 98 a mode of motion, 107 radiant, 109 dynamical equivalent of, 116 effects of, 107 nature of, 98 radiation of, 109 transformation of, 87 Heat engine, Carnot's, 116 of sun, 109 and matter, 100 and work, 114 refraction of, 121 Helmholtz, Von, 45, 86 Hercules, 257, 271, 307 Herschel, Sir J., 3, 4, 7, 226, 228, 281, 299, 301, 310, 321 Sir W., 109, 271-2, 313 Hertz, 138, 159, 182 Hicks, Prof., 13 Hodograph of planets, 247 Hot springs, 90 Huggins, 313-14 Huyghens, 54, 123, 125, 128 Hydrogen, 40, 42, 44, 60, 93, 314, 333 Hypotheses, 3, 338 Ice, 42 Identity of heat and light, 119 light and electricity, 156, 160, 165 aether and electricity, 331 Imponderable, 71 Impressed force, 20 Impressible aether, 78 Induction, electric, 174-5 magnetic, 199 Faraday's theory of, 175 Inertia of matter, 52 of aether, 330 Intensity of light, 28, 146 of heat, 28, 113 of electricity, 184 of gravity, 28 Iron, 42 expansion by heat, 101 contraction by cold, 102 Joule, 85, 114 Jupiter, 26, 68 mass of, 235 satellites of, 149, 178 rotation of, 219 orbital velocity of, 251, 265 size of, 235 distance from sun, 242, 251 density of, 242 and comets, 305 Kant, 317 Kelvin, Lord, 43, 71, 77, 80, 95, 216, 227 on aether, 56-7 on vortex atom, 63 on compressible aether, 291, 315 on light, 151 Kepler's laws, 32 first, 33, 256-9 second, 36, 260-2 third, 37, 263-5 on vortex motion, 221-2 Kinetic energy, 89 electro, 217 Kirchhoff, 43 Laplace, 317 nebular hypothesis, 317 Larmor, Dr., 22, 44, 56, 63, 93, 163 on electrons, 284 on aetherial physics, 22, 327-9 Lavoisier, 42 Law of gravitation, 24 of inverse squares, 27 Laws of electricity, 184 of light, 145 of heat, 113 of motion, 9, 15, 233 Lead, 88, 333 Lebedew, 32, 76, 153 Le Verrier, 25 discovery of Neptune, 25 Leyden jar, 157 Liebnitz, 223 Light, 75 a mode of motion, 122 corpuscular theory of, 123 undulatory theory of, 123, 136 electro-magnetic theory of, 156 path of a ray of, 144 intensity of, 145 reflection of, 136 refraction of, 135 aberration of, 149 composition of, 139 velocity of, 148 zodiacal, 277 transverse vibration of, 130 Lines of force, electric, 173 magnetic, 201-3 Liquefaction of gases, 47 Liquid air, 47 Liquids, 48 Little Bear, 307 Dog, 307 Lockyer, 109 Lodge, Dr., 219 on aether density, 69 on aether, 284, 289, 328, 332 on electric inertia, 330 on electricity, 64, 69, 284, 285 on force, 17 on gravitation, 283 Lorentz on light, 154 Lyra, 307 MacLaurin, 2, 10, 17 Magnesium, 79 Magnet, 21 Magnets, bar, 199 moving, 211 Magnetic axis, 202 field, 199 lines of force, 200 shells, 205 equator, 202 induction, 199 variation, 208 molecules of, 193 polarity, 194 Magnetism of earth, 207-12 of planets, 211 cause of solar, 211 Ampère's theory of, 193 Mars, 68, 79 a magnet, 196 rotation of, 219 size of, 236 orbital velocity of, 251 satellites of, 178 orbit of, 33 Mass, 27, 53, 187 of earth, 235, 242 of planets, 235, 242 of sun, 190 Matter, elements of, 40 properties of, 42, 50 and motion, 41, 322 conservation of, 42 divisibility of, 44 four states of, 48 aetherial basis of, 48, 333 physical constitution of, 334 Maxwell, J. C., 43, 73, 85, 151, 211 on physical lines of force, 168, 203-5, 288 on aether, 59, 206 on magnetism, 205 on electro-kinetic energy, 180, 217 on aether, 58 Mayer, 84, 86, 114, 118 McCullagh, 75 Mechanical energy, 87 Medium, Descartes on a, 221 Kepler on a, 222 Mercury, 68, 79 a magnet, 196 rotation of, 219 eccentricity of orbit, 33 mass of, 242 orbital velocity of, 251 Meteorites, 95, 118 Meteors, 31, 85, 118 Michelson and Morley, 7, 67 Milky way, 79, 309, 314 Molecules, 44 Momentum, 20 Moon, 61 Motion of stars, 310 planetary, 253 of sun, 274 of aether, 80 and work, 95 modes of, 92, 122, 163 first law of, 15, 16, 239 second law of, 19, 244 third law of, 20, 251 Multiple stars, 308 Natural philosophy, 4 Nebulae and aether, 313 structure of, 314 spiral, 322 annular, 320 elliptical, 320 planetary, 321 spectrum of, 314 irregular, 319 Nebular hypothesis, 317 Nebulous stars, 311 Neptune, 68 discovery of, 25 mass of, 235 orbital velocity of, 251, 265 distance from sun, 242 a magnet, 196 Newton's coloured rings, 107 Optics, 72, 98, 122 letter to Bentley, 2, 96 Rules of Philosophy, 3 Principia, 3, 7, 38 emission theory, 123 law of gravitation, 24 atoms, 44 on aether, 98 Nichols and Hull, 32, 153 Ocean, 81, 90 Operations, cycle of, 114 Optics, Newton's, 2, 122 Orbital motions of planets, 266 Orbit of earth, 33 of Venus, 33 Orbits of satellites, 34 of planets, 33-4, 266 moon, 267 stars, 310 sun, 270 Origin of sun's heat, 95 Orion, 79, 307, 314, 319 Oxygen, 40, 44, 60, 93 Parallelogram of forces, 15 Pendulum, 88 Periodic times, 37 Perpetual motion, 93, 220 Phil. Mag., 58, 67, 71, 73, 74, 80 Phil. Trans., 58, 62, 64, 75 Philosophy, Rules of, 3 Phobos, 38 Physical lines of force, 203-6 Pitch of Sound, 105, 120, 139 Plane of ecliptic, 277-9 Planetoids, 31 Planets, minor, 31 origin of, 240 orbits of, 33, 266 electrified bodies, 177 masses of, 242 relative distances of, 242 orbital velocities of, 251 periodic times of, 251 Platinum, 48 Pleiades, 79 Polarization, 176 Potential energy, 87 Potential, electric, 170 magnetic, 194 Pouillet, M., 109 Poynting, 91 Pressure, aetherial, 181 Preston, Prof., 283 Prevost, theory of exchanges, 105 Primitive impulse, 9, 10, 12, 319 Principia, Newton's, 3, 7, 38-9, 122 Properties of matter, 42 Quantity of sun's heat, 109 Query, 18-19 Optics, 72, 122 Radiant heat, 109 energy, 115 Radiation, 104 Radius Vector, 26 Rankine, 103 Rays, actinic, 141 dark heat, 140 infra-red, 141 ultra-violet, 140 Rontgen, 341 X, 341 Rectilinear propagation of light, 144 of heat, 111 Reflection, 160 Refraction, 160 Relative motion of aether and matter, 224-6 Resistance to motion, 17 Resisting medium, 228 Reversible cycle, 116, 118 Rings, vortex, 45 Rival theories, 8 Rivers, 89-90 Roemer, and velocity of light, 148 Rotation of earth, 219 of planets, 219 of sun, 246 Rotatory motion, 93 Rucker, Prof., 59 Rules of Philosophy, 3 first, 3 second, 4 third, 3, 7 Rumford, 98 Running water, 95 Satellites of Mars, 38, 178 Jupiter, 149, 178 Uranus, 254 Neptune, 254 Saturn, 26-7, 68 mass of, 235, 242 orbital velocity of, 251, 265 rotation of, 219 density of, 242 a magnet, 196 satellites of, 178 Schuster, Prof., 8, 218, 311 Sirius, 306, 308-9 Sodium, 43 Solar system, motion of, 257, 271 spectrum, 79, 139 magnetism, 211 Sound, 75 waves, 104, 120 Space, interstellar, 310, 313 Spectroscope, 47, 79 Spectrum analysis, 50, 139 Spiral nebulae, 322 Stars, fixed, 58 number of, 11, 306 binary, 309 distances of, 280 magnitude of, 306, 309 colour of, 79, 308 motion of, 310-11 nebulous, 320 proper motions of, 312 variable, 307 double, 308 clusters of, 314 orbits of, 310 are magnets, 307 Stokes, Sir G., 69, 152, 218 String, 21 Sun, diameter of, 280 constitution of, 79 a magnet, 164, 198-9 mass of, 190 heat of, 109 motions of, 270 orbital velocity of, 35 rotation of, 246 centre of two forces, 186 Tails of comets, 300, 304 straight, 300 curved, 301 multiple, 300 Tait, Prof., 18, 40-1, 88, 247 Telescope, 79 Temperature, 104-5 Terrestrial magnetism, 207-12 gravity, 29 Theory, atomic, 44 rules for making, 3 undulatory, 123 of exchanges, 105 Thermodynamics, first law of, 87, 114 second law of, 116 Thomson, J. J., Prof., 43, 326, 335 Tidal water-power, 88 Tides, 89, 96 Torsion balance, 185 Trade winds, 96, 249 Transformation of energy, 86 of motion, 93 Transverse vibration of light, 130 Tuning-fork, 104 Tympanum, 120 Tyndall on radiation, 104, 106 on light, 71 on Lines of Force, 174 on aether, 77 on atoms, 106 on aether waves, 112 Ultra-violet rays, 140 red rays, 140 Unity of universe, 322-9 Universal gravitation, 24 aether, 58 Universe, 313, 322, 347 Uranus, 68 mass of, 235 density of, 242 orbital velocity of, 265 a magnet, 196 Ursa Major, 307 Minor, 307 Vapour, 49 Variation, magnetic, 209-11 Velocity of light, 148 of electric waves, 182 of heat waves, 148 of falling bodies, 21 of wave motion, 76 Velocity, angular, 250 Venus, 33, 68, 79 a magnet, 197 mass of, 235 rotation of, 219 orbital velocity of, 251 periodic time of, 251 Vibration, atomic, 75 Vibrations, transverse, 130 longitudinal, 130 of sound, 123 Vibratory motion, 91 Vogel, Prof., 308, 312 Vogt, Prof., 332 Volume of sun, 27 Von Asten, 234, 296 Vortex theory, 92, 337 motion, 221-4 atom, 93, 126, 337 rings, 125, 337 Vortices, molecular, 103 Water waves, 124 currents, power of, 95 composition of, 141 power, 88 Wave front, 128 motion, 124, 160 Wave lengths, 120 envelope, 112 Waves, chemical, 141 sound, 104, 120, 124 light, 126 heat, 141 electric, 159 spherical, 112 electro-magnetic, 165 Weight, 29, 69, 84 variation of, 29 pound, 30 Whewell, 3, 221 Winds, 81, 90 energy of, 90 trade, 225 Work, 96 and energy, 84 from heat, 116 Young, Thomas, 54, 64, 67, 123 on aether, 58 fourth hypothesis, 70 Prof., of America, on electric space, 166 Zinc, 88 Zodiacal light, 277-9

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