700 THE UNIVERSE. 



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 indeed. 

 Compared with it sound is propagated with ridiculous slow- 

 ness. 



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 the glowing torch of the world would take 

 fourteen years and two months to reach our ears. 



If we attempt, by an interesting calculation, to compute 

 how long it would require, by our most rapid locomotion, 

 to accomplish a journey from the star which lends us light, 

 we are altogether astonished at the result. According to 

 the calculations of M. Guillemin, an express railway train, 

 starting from the earth on the 1st of January, 1865, and 

 travelling at the rate of thirty-one miles an hour, would 

 only reach the sun in the year 2212 ; that is to say, in 347 

 years, a journey performed by light in a few minutes ! 



We have said what a great lapse of time a luminous ray 

 starting from the Pleiades would require to reach the earth. 

 But the conquests effected by the genius of man over the 

 infinite are not limited to these constellations ; sidereal as- 

 tronomy, aided by the accurate instruments of our epoch, 

 has shown, as we have stated, that the Milky Way is only a 

 congeries of telescopic stars. Now Sir John Herschel thinks 

 that,, according to his photometric calculations, these stars 

 are at such a prodigious distance from the earth that a ray 



