THE MILKY WAY. 15\ 



with another Milky Way, composed of nebulae. The fbrmei 

 constitutes, according to Sir John Herschel's views, an annu- 

 lus, that is to say. an independent zone, somewhat remote from 

 our lenticular-shaped starry stratum, and similar to Saturn's 

 ring. Our planetary system lies in an eccentric direction, 

 nearer to the region of the Cross than to the diametrically op- 

 posite point, Cassiopeia.* An imperfectly seen nebulous spot, 

 discovered by Messier in 1774, appeared to present a remark- 

 able similarity to the form of our starry stratum and the divided 

 ring of our Milky Way.t The Milky Way composed of neb- 

 ulae does not belong to our starry stratum, but surrounds it at 

 a great distance without being physically connected with it, 

 passing almost in the form of a large cross through the dense 

 nebula3 of Virgo, especially in the northern wing, through 

 Comae Berenicis, Ursa Major, Andromeda's girdle, and Pisces 

 Boreales. It probably intersects the stellar Milky Way in 

 Cassiopeia, and connects its drear)' poles (rendered starless from 

 the attractive forces by which stellar bodies are made to ag- 

 glomerate into groups) in the least dense portion of the starry 

 stratum. 



We see from these considerations that pur starry cluster, 

 which bears traces in its projecting branches of having been 

 subject in the course of time to various metamorphoses, and 

 evinces a tendency to dissolve and separate, owing to second- 

 ary centers of attraction is surrounded by two rings, one of 

 which, the nebulous zone, is very remote, while the other is 

 nearer, and composed of stars alone. The latter, which we 

 generally term the Milky Way, is composed of nebulous stars, 

 averaging from the tenth to the eleventh degree of magni- 

 tude,! but appearing, when considered individually, of very 

 different magnitudes, while isolated starry clusters (starry 

 swarms) almost always exhibit throughout a character of 

 great uniformity in magnitude and brilliancy. 



In whatever part the vault of heaven has been pierced by 

 powerful and far-penetrating telescopic instruments, stars or 

 luminous nebulae are every where discoverable, the former, in 



* Sir John Herschel, Attronom., $ C24 ; likewise in his Observations 

 > Nebula and Cluster* of Stars (Phil. Transact., 1833, Part ii.,p. 479, 

 5g. 25) : " We have here a brother system, bearing a real physical re 

 semblance and strong analogy of structure to our own." 



t Sir William Herschel, in the Phil. Trans, for 1785, Part i., p. L57. 

 Sir John Herschel, Astro*., $ 616. (" The nebulous region of the heav- 

 eus forms a nebulous Milky IVay, composed of distinct nebulae, as the 

 other of stars." The same observation was made in a letter he addressed 

 to me in March, 18C9.) $ Sir John Herschel, Astron., $ 58T>. 



