THE MILKY WAY. 141 



cules.* A cubic inch of the polishing slate of Bilin contains, 

 according to Ehrcnberg, 40,000 millions of the siliceous 

 shells of Galionellce. 



The stellar milky way, in the region of which, according to 

 Argelander's admirable observations, the brightest stars of the 

 firmament appear to be congregated, is almost at right angles 

 with another milky way, composed of nebulae. The former 

 constitutes, according to Sir John Herschel's views, an annulus, 

 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 diametri- 

 cally opposite point, Cassiopea.f An imperfectly seen 

 nebulous spot, cHscovered by Messier in 1774, appeared to 

 present a remarkable similarity to the form of our starry 

 stratum, and the divided ring of our milky way. J The milky 

 way composed of nebula, 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 nebulae of Virgo, especially in 

 the northern wing, through Comse Berenicis, Ursa Major, 

 Andromeda's girdle, and Pisces Boreales. It probably inter- 

 sects the stellar milky way in Cassiopea, and connects its 

 dreary poles (rendered starless from the attractive forces by 

 which stellar bodies are made to agglomerate into groups,) 

 in the least dense portion of the starry stratum. 



We see from these considerations, that our starry cluster, 

 which bears traces in its projecting branches of having been 



* Sir John Herscliel, in a letter from Feldhuysen, dated Jan. 13th, 

 1836. Nicholl, Architecture of the Heavens, 1838, p. 22. (See also 

 some separate notices by Sir William Herschel on the starless space 

 which separates us by a great distance from the Milky Way, in the Philas. 

 Transact, for 1817, P. II. p. 328.) 



f Sir John Herschel, Astronom,, 624 ; likewise in his Observations 

 on Nebula and cluster's of Stars (Phil. Transact. 1833, P. II. p. 475, 

 fig. 25) "We have here a brother system, bearing a real physical resem- 

 blance and strong analogy of structure to our own." 



_ J Sir William Herschel, in the Phil. Trans, for 1785, P. I. p. 257. 

 Sir John Herschel, Astron., 616. ('-The nebulous region of the heavens 

 forms a nebulous milky way, composed of distinct nebulae as the other of 

 stars." The same observation was made in a letter he addressed to me 

 in March, 1829.) 



