466 POPULAR SCIENCE MONTHLY. 



that, perhaps, an eighth of these stars are outside the sphere 400B. We 

 may, therefore, infer that the Milky Way stars lie not immensely out- 

 side this sphere. More than this, it does not seem possible to say at 

 present. 



So far as we can judge from the enumeration of the stars in all 

 directions, and from the aspect of the Milky Way, our system is near 

 the center of the stellar universe. That we are in the galactic plane 

 itself seems to be shown in two ways: (1) the equality in the counts 

 of stars on the two sides of this plane all the way to its poles, and (2) 

 the fact that the central line of the galaxy is a great circle, which would 

 not be the case if we viewed it from one side of its central plane. 



Our situation in the center of the galactic circle, if circle it be, 

 is less easily established, because of the irregularities of the Milky 

 Way. The openings we have described in its structure, and the smaller 

 density of the stars in the region of the constellation Aquila, may well 

 lead us to suppose that we are perhaps markedly nearer to this region 

 of its center than to the opposite region; but this needs to be estab- 

 lished by further evidence. Not until the charts of the international 

 photographic survey of the heavens are carefully studied does it seem 

 possible to reach a more definite conclusion than this. 



One reflection may occur to the thinking reader as he sees these 

 reasons for deeming our position in the universe to be a central one. 

 Ptolemy showed by evidence which, from his standpoint, looked as 

 sound as that which we have cited, that the earth was fixed in the 

 center of the universe. May we not be the victims of some fallacy as 

 he was? 



