336 NEWCOMB 



distance we see the stars just as they are. Even within the 

 limit of the universe as we understand it, it is likely that 

 more than one-half the stars which actually exist are too 

 faint to be seen by human vision, even when armed with 

 the most powerful telescopes. But their invisibility is due 

 only to their distance and the faintness of their intrinsic 

 light, and not to any obstructing agency. 



The possibility of dark stars, therefore, does not invalidate 

 the general conclusions at which our survey of the subject 

 points. The universe, so far as we can see it, is a bounded 

 whole. It is surrounded by an immense girdle of stars, 

 which, to our vision, appears as the Milky Way. While we 

 cannot set exact limits to its distance, we may yet con- 

 fidently say that it is bounded. It has uniformities running 

 through its vast extent. Could we fly out to distances equal 

 to that of the Milky Way, we should find comparatively few 

 stars beyond the limits of that girdle. It is true that we 

 cannot set any definite limit and say that beyond this nothing 

 exists. What we can say is that the region containing 

 the visible stars has some approximation to a boundary. We 

 may fairly anticipate that each successive generation of 

 astronomers, through coming centuries, will obtain a little 

 more light on the subject will be enabled to make more 

 definite the boundaries of our system of stars, and to draw 

 more and more probable conclusions as to the existence 

 or non-existence of any object outside of it. The wise in- 

 vestigator of to-day will leave to them the task of putting 

 the problem into a more positive shape. 



