CONTENTS. X.1 



p. 199200. Number of double stars, p. 200208. Uni- 

 formity and diversity of colour ; the latter not a result of an. 

 optical illusion or of the contrast of complementary colours, 

 p. 208210 and Ixxvi. Ixxvii. Notes 343349. Change of 

 brightness, p. 210. Multiple stars (combinations of from 

 three to six stars), p. 211. Calculated elements of orbits, semi- 

 major axes, and periods of revolution iu years, p. 211 214. 



VII. Nefmla, Magettanic Clouds, and Coal-Sacks: Reachability of 

 nebulae ; whether all nebulae are remote and dense clusters of 

 stars? p. 215216 and Ixxx. and Ixxxi. Notes 382 383. 

 Historical account of our knowledge concerning nebulae, 

 p. 217229 and Ixxxiii. Ixxxv. Note 401. Number of 

 nebulae whose positions are determined, p. 229 230 and 

 Ixxxii. Ixxxiii. Notes 392 393. Distribution of nebulae 

 and star clusters into the northern and southern celestial 

 hemispheres, p. 230. Spaces comparatively poor in nebulae, 

 and spaces of maxima of density or frequency of nebulae, 

 p. 230233 and Ixxxiii. Note 398. Form or configuration 

 of nebulae: globular, annular, spiral, double, and "planetary 

 nebulae" or "nebulous stars," p. 233240. Nebula (star- 

 cluster) in Andromeda, p. 122123, 219222, and Ixxxv. 

 Note 403. Nebula in the sword of Orion, p. 220221, 

 240243, Ixxix. Ixxxi. Ixxxvii. Ixxxix. Notes 369, 384, 

 418, 420, 424, and 425. Great nebula round i] Argus, 

 p. 243 244. Nebula in Sagittarius, Cygnus, and Vulpes, 

 p. 244. Spiral nebula in the northern Canis Venaticus, p. 245. 

 The two magellanic clouds, p. 246 254 and xci. Note 445. 

 Black patches or coal-sacks, p. 254 257 and xcii. Notes 456 

 and 458. 



. SOLAK, DOMAIN. 



I. The Sun as a Central Body : Numerical data, p. 269271 

 and xciii. Note 464. Physical character of the Sun's 

 surface ; envelopes of the dark body of the Sun ; spots and 

 facuhe, p. 271282 and xciii. xcvii. Notes 465, 466, 468, 

 470, 474, 479, 480. Diminutions of daylight related by 



