0)1 the Transparency of the Ether. 3 



be concluded that the intrinsic brightness of a unit of its sur- 

 face is much greater than that of tlie sun. The results of 

 spectrum analysis point to a wide variation in the age and 

 temperature of different stars, some being very much farther 

 advanced in the process of cooling than others. It seems 

 certain from these considerations that not only the absolute 

 size but the intrinsic brilliancy vary within very wide limits, 

 some stars emitting several thousand times as much light 

 as others. 



The observations on stellar distribution indicate a much 

 more complicated law than the earlier observers supposed. 

 The more or less marked crowding together of stars in cer- 

 tain regions, with the existing intermediate voids, and the 

 only partial resolvability of these aggregations, show a ten- 

 dency to some system of clustering in which the various 

 orders of magnitudes are actually intermingled. In certain 

 regions the more minute stars are much more sparsely scat- 

 tered than in others, while the distribution should approach 

 more marked uniformity with diminishing magnitude. The 

 absence of vast numbers of stars, with excessive crowding of 

 the smallest magnitudes which such a distribution would 

 require, shows that the telescope can penetrate to the bounds 

 of the system in these regions. 



The observations on the immense extent of the orbits of 

 certain binary stars furnish evidence that there exists a 

 connection between certain stars which have not heretofore 

 been suspected as being members of the same system. The 

 fact that the stars are gathered together in clusters princi- 

 pally in or near the Galactic zone indicates that they must 

 form a part of the Galaxy, since there is no reason why, if 

 they were outside our stellar system, they should not be more 

 uniformly distributed toward the poles of this zone. These 

 evidences of the complexity of the laws of distribution in 

 magnitude and distance furnish strong proof that the present 

 stellar system is finite, and that it does not appear so from 

 the ultimate absorption of the light of the remoter members 

 of an infinite system. Nothing but a cosmical veil of vary- 



3 



