418 NEBULA EOUXD rj AEGUS. SECT. XXXVI. 



ciently insulated and condensed to come under the designation of 

 clusters of stars. Of these the nebula known as Lacaille's 30 

 Doradus is too remarkable to be passed over. It is very large, 

 situate within the Nubecula Major, and consists of an assemblage 

 of nearly circular loops uniting in a centre, in or near which 

 there is a circular black hole. In short, for the number and 

 variety of the objects, there is nothing like this cloud. Within 

 an area of only forty-two square degrees, Sir John Herschel has 

 determined the places, and registered 278 nebulse and clusters of 

 stars, with fifty or sixty in outlying members immediately adja- 

 cent. Even the most crowded parts of the stratum of Virgo, in 

 the wing of that constellation, or in Coma Berenices, offer nothing 

 approaching to it. It is evident, from the intermixture of stars 

 and unresolved nebulosity, which probably might be resolved 

 with a higher optical power, that the nubeculce are to be regarded 

 as systems sui generis, to which there is nothing analogous in 

 our hemisphere. 



Next to the Magellanic clouds the great nebula round 77 Argus 

 is one of the most wonderful objects of the southern sky. It is 

 situate in that part of the Milky Way which lies between the 

 Centaur and the body of Argus, in the midst of one of those rich 

 and brilliant masses, a succession of which is so curiously con- 

 trasted with the profoundly dark adjacent spaces, and surrounded 

 by one of the most beautiful parts of the southern heavens. Sir 

 John Herschel says : " It would be impossible, by verbal de- 

 scription, to give any just idea of the capricious forms and irregular 

 gradations of light affected by the different branches and append- 

 ages of this nebula. Nor is it easy for language to convey a full 

 impression of the beauty and sublimity of the spectacle it offers 

 when viewed in a sweep, ushered in as it is by so glorious and 

 innumerable a procession of stars, to which it forms a sort of 

 climax, justifying expressions which, though I find them written 

 in my journal in the excitement of the moment, would be 

 thought extravagant if transferred to these pages. In fact, it is 

 impossible for any one, with the least spark of astronomical en- 

 thusiasm about him, to pass soberly in review with a powerful 

 telescope, and on a fine night, that portion of the southern sky 

 which is comprised between the 6th and 13th degrees of right 

 ascension, and from 146 to 149 of north polar distance ; such 

 are the variety and interest of the objects he will encounter, and 



