202 COSMOS. 



. e. at very unequal distances from us ; but the relative bright, 

 ness of the separate stars which we estimate as of the 10th ta 

 the 16th magnitude, cannot be regarded as affording sufficient 

 data to enable us in a satisfactory manner to deduce numeri 

 cally from them the radius of their spheres of distances. 94 



In many parts of the Milky Way the space-penetrating 

 power of instruments is sufficient to resolve whole star-clouds, 

 and to show the separate luminous points projected on the dark 

 starless ground of the heavens. We here actually look through 

 as into free space. " It leads us," says Sir John Herschel," irre- 

 sistibly to the conclusion that in these regions we see fairly 

 through the starry stratum." 96 In other region* we see as it 

 were through openings and fissures, remote world-islands, or 

 outbranching portions of the annular system ; in other parts, 

 again, the Milky Way has hitherto been fathomless, even with 

 the forty-feet telescope. 96 Investigations on the different in- 

 tensity of light in the Milky Way, as well as on the magni- 

 tudes of the stars, which regularly increase in number from the 

 galactic poles to the circle itself (an increase especially ob- 

 servable for 30 on either side of the Milky Way in stars 

 below the llth magnitude, 97 and therefore in -ff- of all the 



94 Encke, in Schumacher's Astr. Nachr., no. 622, 1847, 

 P. 341-346. 



98 Outlines, pp. 536, 537, where we find the following 

 words on the same subject: " In such cases it is equally 

 impossible not to perceive that we are looking through a sheet 

 of stars nearly of a size, and of no great thickness compared 

 with the distance which separates them from us." 



96 Struve, Etudes stell., p. 63. Sometimes the largest 

 instruments reach a portion of the heavens, in which the 

 existence of a starry stratum, shining at a remote distance, is 

 only announced by " an uniform dotting or stippling of the 

 field of view." See, in Observations at the Cape, p. 390, the 

 section k ' On some indications of very remote telescopic 

 branches of the Milky Way, or of an independent sidereaJ 

 system or systems bearing a resemblance to such branches." 

 * OT Observations at the Cape, 314. 



