CHAPTERS ON THE STARS. 307 



CHAPTEKS ON THE STAES. 



By Professor SIMON NEWCOMB, U. 8. N. 

 THE STRUCTURE OF THE HEAVENS. 



ri THE problem of the structure and duration of the universe is the 

 -*- most far-reaching with which the mind has to deal. Its solution 

 may be regarded as the ultimate object of stellar astronomy, the 

 possibility of reaching which has occupied the minds of thinkers since 

 the beginning of civilization. Before our time the problem could be 

 considered only from the imaginative or the speculative point of view. 

 Although we can to-day attack it by scientific methods, to a limited 

 extent, it must be admitted that we have scarcely taken more than the 

 first step toward the actual solution. We can do little more than state 

 the questions involved, and show what light, if any, science is able to 

 throw upon the possible answers. 



Firstly, we may inquire as to the extent of the universe of stars. 

 Are the latter scattered through infinite space, so that those we see are 

 merely that portion of an infinite collection which happens to be within 

 reach of our telescopes, or are all the stars contained within a certain 

 limited space ? In the latter case, have our telescopes yet penetrated to 

 the boundary in any direction? In other words, as, by the aid of 

 increasing telescopic power, we see fainter and fainter stars, are these 

 fainter stars at greater distances than those before known, or are they 

 smaller stars contained within the same limits as those we already know? 

 Otherwise stated, do we see stars on the boundary of the universe? 



Secondly, granting the universe to be finite, what is the arrange- 

 ment of the stars in space? Especially, what is the relation of the 

 galaxy to the other stars? In what sense, if any, can the stars be said 

 to form a permanent system? Do the stars which form the Milky Way 

 belong to a different system from the other stars, or are the latter a 

 part of one universal system? 



Thirdly, what is the duration of the universe in time? Is it fitted 

 to last forever in its present form, or does it contain within itself the 

 seeds of dissolution? Must it,- in the course of time, in we know not 

 how many millions of ages, be transformed into something very different 

 from what it now is? This question is intimately associated with the 

 question whether the stars form a system. If they do, we may suppose 

 that system to be permanent in its general features; if not, we must 

 look further for our conclusion. 



