326 HUMBOLDT'S COSMOS : 



trations ; and, further, because they do really in many cases 

 convey to the mind larger and clearer conceptions of relative 

 space. We admit at once that few of the distances expressed 

 by astronomy are in strictness brought home to the under- 

 standing, even by those most familiar with such contempla- 

 tions. One of the smallest celestial admeasurements, that 

 of the Moon's distance from the Earth, can only be appre- 

 ciated by bringing in other more common relations of com- 

 parison. And when we find that the star 61 Cygni is 592,000 

 times as distant as the Earth from the Sun, our reason, while 

 satisfied of the certainty of the means by which this result is 

 obtained, can raise no idea commensurate in any sort or kind 

 with the vast array of numbers set before us. But we may 

 aid ourselves in some degree by bringing in a new element 

 that of time as a measure of space. We know from other 

 sources that light is transmitted through space at the rate of 

 more than eleven millions of miles in a minute. The distance 

 of the Star just mentioned is such, that light proceeding from 

 it, and travelling unceasingly at this rate, would require 

 more than nine years to reach the earth ! Now this new 

 mode of measurement is as incomprehensible as the other, in 

 a strict sense of the term ; yet our conception is felt to be 

 enlarged by its use ; and new relations are perceived, even 

 by those who look on the mere surface of the science. 



Another case we will put ; because, amidst a like host of 

 numbers, a practical conclusion is involved in which we of 

 this nether world are not wholly unconcerned. With his 

 wonted sagacity the elder Herschel obtained proof of what 

 had been the prior suggestion of Bradley, that our Sun, with 

 the whole attendant planetary system, has a proper con- 

 tinuous motion in space ; of which motion he himself indi- 

 cated the course and direction. With the methods employed 

 in this great research we have no present concern ; but may 

 simply mention that time and the observations of later 



