NEBULAE. 27 



matta, with a nine-inch Newtonian reflector, of which Sir 

 John Herschel included only 206 in his catalogue.*" Simi- 

 lar results have recently been published by Bond and Miid- 

 ler. The number of nebulae, compared with that of double 

 stars, appears, therefore, according to the present condition 

 of science, to be in the ratio of 2 : 3 ; although it must not 

 be forgotten that under the designation of double stars are 

 included those which are merely optically double, and that 

 hitherto alterations of position have only been observed in a 

 ninth, or perhaps but an eighth portion of the whole number. f 



The above numbers — 2299 nebula?, with 152 clusters of 

 stars, in the Northern, and only 1239 nebulae, with 236 clus- 

 ters of stars, in the Southern Catalogue — show that the south- 

 ern hemisphere, with a smaller number of nebulae, possesses 

 a preponderance of clusters of stars. If we assume that all 

 nebulae are, from their probable constitution, resolvable, as 

 merely more remote clusters of stars or stellar groups, com- 

 posed of smaller and less thronged, self-luminous celestial bod- 

 ies, this apparent contrast (whose importance has been the 

 more noticed by Sir John Herschel$ in consequence of his 

 having employed reflectors of equal powers in both hemi- 

 spheres) indicates, at least, a striking difference in the nature 

 and cosmical position of nebulae, that is to say, in reference 

 to the directions in which they present themselves to the ob- 

 servation of the inhabitants of the earth in the northern or 

 southern firmament. 



We owe to the same great observer our first accurate knowl- 

 edge of, and cosmical survey of, the distribution of nebulae and 

 groups of stars throughout the entire heavens. With a view 

 of investigating their position, relative local accumulation, 

 and the probability or improbability of their being arranged 

 in accordance with certain characteristic features, he classi- 

 fied between three and four thousand objects graphically, in 

 divisions, each embracing a space measuring 3° Declination 

 and 15m. Right Ascension. The greatest accumulation of 

 nebulous spots occurs in the northern hemisphere, where they 

 are distributed through Leo Major and Leo Minor ; the body, 

 tail, and hind feet of the Great Bear ; the nose of Camelo- 

 pardalus ; the tail of the Dragon ; Canes Venatici ; Coma 

 Berenices (where the north pole of the galaxy is situated); k 



* Op. cil., § 7. Compare Dunlop's Cat. of Nebula: and Clusters of 

 the Southern Hemisphere, in the Philos. Transact, for 1828. p. 1 14—146 

 t Cosmos, vol. iii., p. 200. t Observations at the Cape, § 105-107. 

 $ In the Cosmos, vol. iii., p. 144, lines 5 and 6 from the top, by an 



