OUR PLACE IN SPACE 361 



All this would seem to indicate an average distance for six- 

 teenth and seventeenth magnitude stars as somewhere from 

 twenty to sixty thousand light-years ; the number is purposely 

 stated very vaguely, because of a possible absorption of light 

 through very long spaces. This appears to be the present limit 

 of telescopic visibility. 



The present calculated distance of Sirius is somewhat under 

 ten light-years (8.6 is the latest estimate). Herschel's figure, 

 therefore, was not far out of the way if we set this distance at 

 ten light-years. It is possible, though by no means certain, 

 that we can see somewhat farther even than he supposed. 



If the solar system were situated anywhere near the centre 

 of the stellar universe, as some recent fanciful philosophies of 

 creation suppose, then of course our telescopes would be able 

 to sweep across a cosmos of twice these computed dimensions, 

 or of from fifty to a hundred thousand light-years. There is 

 little reason to suppose, however, that we are at the centre of 

 any system or anywhere near it. But even thirty thousand or 

 fifty thousand light-years would mean a universe several times 

 more vast than the utmost limit conjectured by 1'Hermite. 

 And the figure of I'Hermite was based upon the idea that the 

 total light of the stars was equal to about one-tenth full moon- 

 light. More recent and more accurate calculations seem to 

 indicate that it is not much more than one-sixtieth full moon- 

 light. In a word, I'Hermite's estimate may have been five or 

 six times too high. So, if we could rely in any way upon our 

 present assumptions, we might infer that the present powers 

 of the telescope would reveal the existence of a universe perhaps 

 a hundred times more vast than any which can be accounted 

 for now from measures of light, or than Newcomb deems pro- 

 bable from the methods employed by him. 



It is obvious that we can know nothing of the real distance 

 of the farther stars until the question of the absorption of light 

 is settled. Of course, if there is the slightest dimming of the 

 light, the boundaries of the universe will be to us forever un- 

 known. Presumptuous in the last degree is it, therefore, to 

 attempt to fix the position of the solar system in space. A 

 microbe upon the surface of a microscopic drop of mist in a fog 

 covering the Atlantic Ocean would not be more hopelessly 

 situated in his endeavours to discover his whereabouts. 



In the days to come, when the parallaxes of some thousands 



