THE SIDEREAL UNIVERSE. 733 



pass round the globe. But the depth of the heavens does 

 not stop short at the group of the Pleiades : on the con- 

 trary, they belong to its nearer regions.^ 



Space being infinite, and our minds finite, they can 

 only take in some small portions of it, and yet, though 

 these are very limited compared to the field of immensity, 

 they are enough to confound the human comprehension. 

 It would be puerile to try and define them by numbers : 

 all the resources of our intellect would not suftice for such 

 an attempt. The space which light traverses in a year 

 far outstrips the measure of our perceptive facidties; 

 we are not surprised when we remember that it clears 

 the distance separating us from the sun, that is to say, 

 91,328,600 miles, in 8 minutes 18 seconds; and yet it is 

 this light which in its dazzling progress serves to measure 

 the vast distances between the globes, and to give us a 

 grand idea of some fragments of the infinite ! 



As light passes through 77,000 leagues in a second, 

 the speed of anything we can place beside it is low in- 

 deed. Compared with it sound is propagated with ridicii- 

 lous slowness. • 



Supposing the immense abyss interposed between the 

 earth and the sun were capable of transmitting sonorous 

 undulations, it has been calculated that sound produced 

 on the surface of tlie glowing torch of the world Avould 

 take fourteen years and two months to reach our ears. 



If we attempt, by an interesting calculation, to com- 

 pute how long it would require by means of our most 

 rapid locomotion to accomplish a journey from the star 



'■ The Alpha of the Centaur, one of the nearest stars to us, which is only 



about 8,00(),00ri,000 geographical lengues from the earth, sends us its light in 



three years; and the pole-star, which is more than 70,000,000,(100 leagues, iu 



a quarter of a century. 



93 



