202 COSMOS. 



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

 ness of the separate stars which we estimate as of the 1 Oth to 

 the 1 6th 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.** 



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." 95 In other regions 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 j-f of all the 



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

 P. 341-346, 



85 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." 



59 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 " On some indications of very remote telescopic 

 branches of the Milky Way, or of an independent sidereal 

 system or systems bearing a resemblance to such branches." 



97 Observations at the Cape, 314. 



