DISTRIBUTION OF THE STARS. 



183 



tributed at uniform distances from each other along the 

 middle of the Milky Way, and obtained the following re- 

 sults: 



According to this table, the distance of stars of the sixth 

 magnitude, which are just visible to the naked eye, is 

 about eight times as great as that of stars of the first mag- 

 nitude. The distance of stars of the twelfth magnitude, 

 by which is meant those stars which were barely visible 

 in Herschel's twenty feet telescope, is 228 times as great 

 as that of stars of the first magnitude. 



Assuming the preceding relative distances, and also 

 that the average parallax of a star of the second magni- 

 tude is 0".116, we obtain the absolute distance of stars of 

 each magnitude as given on page 168. 



Professor Encke, of Berlin, has criticized these specula- 

 tions of Sfruve with some severity. He thinks that 

 they involve several hypotheses which are altogether 

 unwarrantable. They assume, 



I. That the apparent brightness of the stars is the 

 simple effect of distance, so that we can assign the 

 radius of the sphere within which the stars of each class 

 are comprised. Encke objects to this assumption, 1. That 

 it is contrary to the analogy of our solar system, in 

 which the magnitudes of the planets are very unequal. 



