INDEX. 



211.' 



fcptiry, conjectures regardinj;, 29; com- 

 pared to the nij-thic period of history, 

 20 ; fallacy of attempts atmeasureraent 

 of, 30 ; portions between cosmical bod- 

 ies not void, 31 ; its probable low tem- 

 perature, 35. 



Spectra, the prismatic, 44; difference of 

 the dark lines of, according to their 

 sources, 45. 



" Sphtera aplanes" of Macrobius, 27. 



Spurious diameter of stars, 130. 



Star of the Magi, Ideler's explanation of 

 the, 154. 



Star of St. Catharine, 137. 



Star systems, partial, in which several 

 suns revolve about a common center 

 of gravity, 204. 



Stars, division into wandering and non- 

 wandering, dates at least from the early 

 Greek period, 27; magnitude and visi- 

 bility of the, 48 ; seen through shafts 

 of chimneys, 57 ; undulation of the, 58, 

 59 ; observation of, by daylight, 66 ; 

 scintillation of the, 73 ; variations in its 

 intt^nsity, 76 ; the brightest the earliest 

 named, 89; rays of, 52, 127, 128 ; color 

 of, 130 ; distribution of, 140 ; concentric 

 rings of, 149 ; variable, 161 ; vanished, 

 163 ; periodically changeable, 164 ; non- 

 luminous, of doubtful existence, 187 ; 

 ratio of colored stars, 209. 



Steinheil's experiments on the velocity 

 of the transmission of electi'icity, 87 ; 

 his photometer, 93. 



Stellar clusters or swarms, 140. 



Struve on the velocity of light, 82; his 

 estimate of the number of the tixed 

 stars, 117 ; on the Milky Way, 139; his 

 Dorpat Tables, 20o ; on the contrasted 

 colors of multiple stars, 207 ; calcula- 

 tion of the orbits of double stars by. 211. 



Sun, the, described as " a perpetual north- 

 ern light" by Sir William Herschel, 34 ; 

 in intensity of light merely one of the 

 fainter tixed stars, 95 ; its place prob- 

 ably in a comparatively desert region 

 of the stariy stratum, and eccentric, 1.50. 



Suns, self-luminous cosmical bodies, 199. 



Fable of photometric aiTangeraent of 190 

 fixed stars, 100 ; of 17 stars of first mag- 

 nitude, 102 ; of the variable stars, by 

 Argelander, 172, and explanatory re- 

 marks, 172-177 ; of ascertained paral- 

 laxes, 193 ; of the elements of the or- 

 bits of double stars, 213. 



Telescope, the principle of, known to the 

 Arabs, and probably to the Greeks and 

 Romans, 42, 43 ; discoveries by its 

 means, 61 ; successive improvements 

 of the, 62; enormous focal length of 

 some, 63 ; Lord Rosse's, 65 ; Bacon's 

 comparison of, to discovery ships, 130 ; 

 penetrating power of the, 145, 146. 



Telesio, Bernardino, of Cosenza, his views 

 of the phenomena of inert matter, 16. 



Temperature, low, of celestial space, 35; 

 uncn'tainty of results vet obtained, 36; 



ita influence on the climate 'A the earth, 



37. 



Temporary stars, list of, 155 ; notes to, 

 155-160. 



Ternary stars, 210. 



Timur Ulugh Beg, improvements in prac- 

 tical asti'onomy in the time of, 91. 



Translation in space of the whole solai 

 system, 195 ; first hinted by Bradlej', 

 195; verified by actual observation by 

 William Herschel, 196; Argelander, 

 Struve, and Gauss's views, 196. 



Trapezium in the great nebula of Orion, 

 investigated by Sir Wm. Herschel, 203. 



Tj'cho Brahe, his vivid description of the 

 appearance of a new star, 152 ; his the- 

 ory oi' the formation of such, 154. 



"Ultimate mechanical cause" of all mo- 

 tion, unknown, 24, 25. 



Undulation of the stars, 58, 59. 



Undulations of rays of light, varioua 

 lengths of, 84. 



Unity of nature distinctly taught by Aria- 

 totle, 13-15. 



Uranological and telluric domain of the 

 Cosmos, 26. 



Uranus observed as a star by Flamstcad 

 and others, 114. 



Vanished stars, 163 ; statements about 

 such to be received with great caution, 

 163. 



Variable brightness of multiple and dou- 

 ble stars, 209. 



Variable stars, 160-161 ; mostly of a red 

 color, 165; irregularity of their periods, 

 167 ; table of, 172. 



Velocity of light, 79 ; method's of determ- 

 ining, 80; applied to tlie determination 

 of the parallax, 195. 



Visibility of objects, 55 ; how modified, 56. 



Vision, natural and telescopic, 41; aver- 

 age natural, 47, 48 ; remarkable in- 

 stances of acute natural, 52, 55. 



Wheatstone's experiments with revolv- 



iivg mirrors, 45 ; velocity of electrical 



light determined by, 86. 

 White Ox, name given to the nebula now 



known as one of the Magellanic clouds, 



91. ■ 

 Wollaston's photometric researches, 95. 

 Wright, of Durham, hisview of the origin 



of the Ibrm of the Milky Way, 149. 



Yggdrasil. the World-tree of the Edd«- 

 Songs, 8. 



Zodiac, period of its introduction into the 

 Greek sphere, 119 ; its origin among the 

 Chaldeans, 120 ; the Greeks borrowed 

 from them only the idea of the division, 

 and filled its signs with their own catas 

 torisms, 120; great antiquity of the In- 

 dian very doubtful, 121. 



Zodiacal lidit, Sir John Herschel on tha 

 40. 



THE END. 



