Page:In the high heavens.djvu/386

382 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

, Dr., the photograph of the Great Nebula in Andromeda, 158 Rowland, Prof., solar researches, 168

, in remote antiquity, 19 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