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
Rowland, Prof., solar researches, 168
S
through the telescope, 124
formation of his rings, 219
Schiaparelli's work on Mars, 141, 144
Schuster, Prof., and the coronal spectrum, 94
the Aurora Borealis, 163
electric connection between the sun and planets, 164
Sirius, in remote antiquity, 20
and the spectrum of hydrogen, 165
Sidereal system, our, mass, shape and size of, 210
Prof. Newcomb's calculation, 210
critical velocity of the luminous portion, 210
Sidereal system, the dark bodies in, 211-212
the dark more numerous than the bright, 240-241, 245-246
is it isolated? 208
stars outside it, 209
Sky, area of in degrees, 238
Smith, Prof., Lawrence, on the origin of meteorites, 308
Space, is it infinite? 247-252
systems in space, 208
Spectroscopy, the reading of the spectrum, 149, 150
application of spectrum analysis to the heavenly bodies, 151-154, 157, 165-166
spectrum of a nebula, 155
movement in the line of sight, 159, 166, 172-174
explanation of the method, 175-179
Keeler's measurements, 160-162
the spectrum and terrestrial elements, 168
the spectrum of the sun compared with that of the earth at sun-heat, 169
the voyage of the solar system, 28-30
observation of the solar prominences, 86-87
observation of the solar corona, 92-94
the problem of Algol, 179-184
measurement of stars, 185-187
spectroscopic solution of double stars, 191
(See also Huggins)
Stars, velocity of, 12
lustre and distance, 15
apparent contiguity, 235-236
proper motion of, 17
old method of measuring movement, 161
spectrum analysis, 151
"fixed stars" a misnomer, 171
white stars, temperature of, 165
Polaris in antiquity, 20
Arcturus, distance of, 161
Algol, problem of, 179-184
Northern Crown, new star in, 154-155
Cygnus, new star in, 215, 216
61 Cygni, distance of, 13
