570 



INDEX. 



OBSEBVATOBT, women's work in the, 



97, 169 



prosaic labours in, 98-99 

 conditions of observation, 100 

 impediments to work, 101 

 the Lick, 103-106 

 the Lick refractor, 105 

 meridian circle, 107-110 

 equatorial, 110 

 Orion, Great Nebula in, 127, 133- 



134, 265, 317 

 composition of, 131 

 presence of hydrogen in, 136- 



138 

 unknown spectrum lines in, 



137 



magnitude of, 138 

 Orionis Theta, 129, 130 



121, 122 

 distance of cluster, 123 



Perseids, 245 



Photographing the stars, 292, 318 

 atmospheric difficulties, 294 

 Janssen's sun-pictures, 295 

 photographs of moon, 296 

 photographs of planets, 297 

 of Jupiter, 298 

 of Saturn, 299 

 of extra-telescopic, 300, 30 1 

 Mr. Roberta's work, 303, 315 

 instruments for photography, 



305-310 

 charting the heavens, 311, 



311i 



work at the Draper Memorial, 

 318 



Planets, rotation of, 54 

 atmosphere of, 86 

 how to weigh, 115, 172-176 

 Mars, Venus, Jupiter, 142 

 compared with stars, 149- 



150 



and tiieir satellites, 151, 168 

 relative size of, and sun, 183 

 heated stage of, 193 

 names of, 195, 200, 201 



Pleiades, 266, 316 



RBFBAOTION, 102, 103 



Roberts, Dr. Isaac, and celestial 



photography, 303 

 charting the heavens, 313 

 photograph of the Andromeda 



Nebula, 315, 317 

 photograph of the Pleiades, 

 316 



SAITBWICH Islands and lunar land- 

 scape, 91, 92 

 Saturn, period of revolution, 113, 



114 



bands, 115 

 weight, 116 

 rings, 116-118, 121 

 photograph of, 299 

 SchiapareUi, observation of Mer- 

 cury and Venus, 145-147 

 Vn'a "canals" on Mars, 165-167 

 Sea-waves, great, caused by Kra- 



katoa, 334 

 Senses, two, useless on the moon 



92, 93 



Shooting stars (see Meteors) 

 Sound, eruption of Krakatoa, 331- 



334 



detonation of fireballs, 221 

 Spectroscope and star-movements, 



262 



motion in line of sight, 268-272 

 explanation of, 272-289 

 musical illustration of , 287-289 

 light and colour rays, 277 

 colour affected by motion, 278, 



279, 281 



value of the dark lines, 283 

 Spectrum analysis, 19, 135-137, 



262 

 elements common to earth and 



sun, 19 

 material unity of the universe, 



263 



Spontaneous generation, 354 

 Stars, growth and decay of, 35, 37 

 dark, 37, 38 

 double, 129 

 colour of, 278-281 



