A
Critical velocities on the sun and planets, 314
Cygnus, new star in, 215-216
61 Cygni, distance of, 13
D
Gravitation, comets and the law, 199
the law outside our system, 200-204
gravitation and the binary stars, 203
what is known about gravitation, 204-206
gravitation on the moon, 47
""Jupiter, 50
""the sun, 371
Helmholtz's solar theory, 371-372
Great Bear, the, in remote antiquity, 20
now and 36,000 years hence, 173, 175
100,000 years hence, 177
the system of Mizar, 192
detection of Mizar's spectroscopic double, 193
distance and mass of its components, 194-195
period of Xi Ursæ Majoris, 202
Groombridge No. 1830, velocity of, 12, 209
its distance and proper motion, 208
its relation to our sidereal system, 211
H
size and weight of his satellites, 43, 115
the four satellites known to the Chinese, 95
why the satellites are not distinguishable, 96-99
their distances and periods of revolution, 110
discovery of the fifth satellite, 99, 105
lustre, size, distance, period of the fifth satellite, 107-108
orbit of the fifth satellite, 112
the problem of the satellites, 101
the work of Laplace, 102
interest of the discovery, 100, 103
value of the discovery, 104, 109
Kepler' s law, 109-110
K
difference from meteors, 296-297
constituent elements of, 299
composition of meteorites, 348-352
Ovifak and Coon Butte "irons," 349-352
not cometary, 307
Tschermak's volcanic doctrine, 307, 310
Lockyer and Prof. Newton's theory, 308
origin of meteorites, 308-309
meteorites volcanic ejects, 310
whence, 311-355
objections considered, the atmosphere, 341, 345
career of a meteorite, 345, 347
recapitulation of argument, 353-355
Milky Way, the, in remote antiquity, 20
Million years ago, the star-groups of a, 12, 15-18, 20
Mizar, the system of (see Great Bear).
Molecules (see Gases).
Moon, the, of the coal measures, 18
conditions of life on the, 45-48
compared with Mars, 121
absence of atmosphere, 126, 131
Mott, Mr. A., his theory of lunar atmosphere, 128
N
Planets, the Nebular Hypothesis, 220-222
search for an intra-Mercurial planet, 108-109
Pleiades, the theory of a central sun, 231-235
Pole Star, the, in remote antiquity, 20
of the future, 56
Pole, the celestial, photographed, 53
shifting of the, 55-56, 62
its period of rotation, 56
Pole, the terrestrial, the position of, 57-60
its position in antiquity, 59
its movements, 61-63, 65-67
how detected, 68-73
extent of its shift and period of revolution, 74
Probability, the doctrine of, in astronomy, 220, 241, 245, 328-331
R
Alpha Centauri, 208, 330
Groombridge No. 1830, 12, 208, 209, 211
binary, 15
colour problem, 152
Huggins' explanation, 153
the spectroscope, 191
in proof of universal gravitation, 201
actual and apparent propinquity, 201
movements discovered by Herschel, 202
Xi Ursæ Majoris, 202
Star-groups of a million years ago, 12, 15-18, 20
transformation of, 172
Stumpe, Prof., and the movement of the solar system, 24-25
Sun, the, of the coal measures, 17-18
voyage through space, 21-31
the direction of voyage, 21-25
velocity, 21, 26, 28, 30, 31
new method of studying the prominences, 86-87
study of the corona, 87, 92-93
nature of the corona, 164
Schuster's researches, 94
rotation of the photosphere, 93
solar atmosphere, 126
electric connection between the
sun and planets, 164
velocity of sun's rotation determined by spectroscope, 166
researches of Professor Rowland, 168
solar spectrum compared with that of earth at sun-heat, 169
the Nebular Hypothesis, 226-229
theory of a central sun, 231-235
history of the sun, 242
future extinction of the sun, 243, 275
waste of solar heat, 263
the heat problem, 266-272
Helmholtz's theory, 269, 369
terrestrial elements in the sun, 300
Sun, solar explosions, 339, 344
the molecular theory and solar physics, 369
T