OF THE COSMOS. MILKY WAY. 129 



above., takes place at a Centauri : it is a bifurcation 

 which, according to older views, continues to the constel- 

 lation of Cygnus. Proceeding from a Centauri, a narrow 

 branch goes northwards towards the constellation Lupus, 

 where it loses itself: then a division shows itself at 

 y Normse. The northern branch runs into irregular 

 shapes until near the feet of Ophiuchus, where it entirely 

 disappears ; the southern branch now becomes the main 

 stream, and passes through the Altar and the tail of 

 the Scorpion to the bow of Sagittarius, where it cuts the 

 Ecliptic iii 276 longitude. Further on we recognise it 

 still, but in an interrupted patchy form, passing through 

 Aquila, Sagitta, and Vulpecula, to Cygnus. Here begins a 

 very irregular district, where, between e, a, and y Cygni, 

 there is a broad dark space, which Sir John Herschel ( 257 ) 

 compares to the coal-sack in the Southern Cross, and which 

 forms, as it were, a centre whence three partial streams 

 diverge. One of these, which has most strength of light, 

 may be pursued in, as it were, a retrograde course past 

 jg Cygni and s Aquilse : it does not however unite with the 

 branch before spoken of, which goes to the foot of Ophiuchus. 

 There is still a considerable additional piece of the Milky 

 Way, which extends from the head of Cepheus, and therefore 

 in the vicinity of Cassiopeia, from which constellation we 

 began our description, to Ursus Minor and the North Pole. 

 Prom the extraordinary improvement which, by the applica- 

 tion of large telescopes, has gradually been made in the know- 

 ledge of the sidereal contents, and the differences in respect to 

 concentration of light, in different parts of the Milky Way, 

 views of merely optical projection have been replaced by 

 what may rather be deemed views of physical character and 



VOL. III. K 



