eptune, 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

Ampere, 192

Ampere'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, 4