, 



introduction into the Greek 

 sphere, 162. 



Light, always refracted, 54; pris- 

 matic spectra differ in number of 

 dark lines acco-ding to their 

 source, 55, 56; polarisation of, 

 57; velocity of, 105; .ratio of 

 solar, lunar, and stellar, 126; 

 variation of, in stars of ascer- 

 tained and unascertained period- 

 icity, 228, 240. 



Light of the sun and moon, Euler's 

 and Michelo's estimates of the 

 comparative, 127. 



Limited transparency of the celestial 

 regions, 46. 



Macrobius, " Sphaera aplanes" of, 

 31. 



Madler, on Jupiter's satellites, 67; 

 on the determined periods of 

 variable stars, 225; on future 

 polar stars, 245; on non-lumi- 

 nous stars, 255; on the centre of 

 gravity of the solar system, 269. 



liagellanic clouds, known to the 

 Arabs, 122. 



Magnitude of the stars, classes of, 

 120, 121. 



Malus, his discoveries regarding 

 light, 57. 



" Mappa ccelestis" of Schwinck, 

 189. 



Ma-tuan-lin, a Chinese astrono- 

 mical record of, 146. 



Mayer, Christian, the first special 

 observer of the fixed stars, 275. 



Melville Island, temperature of, 43. 



Michell, John, 126; applies the 

 calculus of probabilities to small 

 groups of stars, 274; little re- 

 liance to be placed in its indivi- 

 dual numerical results, 275. 



Michelo's comparative estimate of 

 the light of the sun and moon, 

 177. 



Milky Way, average number of stars 



in, and beyond the, according to 



Struve, 188; intensity of its light 



the vicinity of the Southern 



Cross, 198; its course and direr- 

 tion, 199; most of the new stars 

 have appeared in its neighbour- 

 hood, 220. 



Morin proposes the application of 

 the telescope to the discovery of 

 the stars in daylight, 51, 86. 



Motion, proper, of the fixed stars, 

 248: variability of, 252. 



Multiple stars, 175, 271; variable 

 brightness of, difference of opinion 

 regarding, 286. 



Nebulae, probably closely crowded 

 stellar swarms, 44. 



Neptune, the planet, its orbit used 

 as a measure of distance of 61 

 Cygni, 277. 



New stars, 204; their small num- 

 ber, 204 ; Tycho Brahe's descrip- 

 tion of one, 205; its disappear- 

 ance, 206; speculations as to 

 their origin, 218; most have ap- 

 peared near the Milky Way, 

 220. 



Newton, embraces by his theory of 

 gravitation the whole uranological 

 portion of the Cosmos, 23. 



Non -luminous stars, problematical 

 existence of, 254. 



Numerical results, exceeding the 

 grasp of the comprehension, fur- 

 nished alike by the minutest 

 organisms and the so-called fixed 

 stars, 34; encouraging views on 

 the subject, 35. 



Optical and physical double stars, 

 272; often confounded, 272. 



Orbits of double stars, calculation 

 of the, 287 ; their great eccentri- 

 city, 287; hypothesis, that the 

 brighter of the two stars is at 

 rest, and its companion revolves 

 about it, probably correct, and a 

 great epoch in cosmical know- 

 ledge, 288. 



Orion, the six stars of the trapezium 

 of the nebula of, probably subject 

 to peculiar physical attraction, 287. 



