Critical velocities on the sun and planets, 314
Cygnus, new star in, 215-216
61 Cygni, distance of, 13
D
Dunér's measurement of the rotation of the sun, 166
E
its past history, 34, 36
its ancient heat-stages, 36
gaseous and nebular stage, 37
and man, 39
an average specimen of a world, 39
its movement on its axis, 64
is the earth rigid? 75, 76
distances from the sun, 116
""Mars, 117
absence of free hydrogen, why, 128-131
the fate of oxygen, 137
and the Nebular Hypothesis, 228
the destiny of species, 253-256
coal supply, 257
stores of energy, 258
sources of heat, 261-263
viewed from Alpha Centauri, 330
equilibrium of our atmosphere, 372
(See also Volcanoes.)
Eclipse, the, of 1893—
conditions essential to observation, 77
duration of totality, 78
the journey of the moon's shadow, 79-83
speed of the journey, effect of curvature of the globe, 82, 83
the best sites for observation, 83-84
present-day problems for solution, 85-88
Eclipse, preliminary inquiries, 88-91
Epsilon Lyræ, 201
Euclid and the problem of space, 249-251
Eyes of extinct animals, 17
F
G
character of molecules, 356-360
dimensions of molecules, 361
velocity of molecular movements, 360, 361
pressure of gases, 362-364
effect of heat, 365, 369
vibration of molecules, 366, 367
experiments with hydrogen, 368
heat and light due to vibration, 369
iron-gas spectrum, 368
the molecular theory and solar physics, 369
Helmholtz's solar researches, 369-370
free hydrogen absent from our atmosphere, 128-131
hydrogen in Sinus and Vega, 131
knowledge of spectrum of hydrogen due to Sirius, 165
hydrogen in Mars, 133
Dr. Stoney's gaseous theory, 128
oxygen on Mars, 133
velocity of aqueous vapour molecules, 133
Dr. Huggins' discoveries, 157
Geology, the uniformitarian hypothesis controverted, 336
Gill, Sir David, and the photographic chart of the heavens, 167
Gravitation, the law of, 196
is it universal? 188, 197
planets and the law, 198
the law in our system, 199
