734 THE UNIVERSE. 



which lends us Hght, 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 astronomy, aided by the accurate instruments of 

 our epoch, has shown, as we liave 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 of light starting from one of 

 them would take 2000 years to reach us. 



Yet human investigation penetrates much farther than 

 this. When the observer carries his investigations more 

 deeply into immensity, «\vhen he reaches those nebuke 

 which lie on the confines of space, the distances are so 

 great that they confound the imagination, and figures no 

 longer suffice to represent them. According to calcula- 

 tions, says Humboldt, which are not devoid of probability, 

 light, notwithstanding its tremendous speed, requires more 

 than two millions of years to traverse the enormous distance 

 which separates us from these stars. Hence, while the 

 telescope still displays to our eyes the luminous gleam of 

 one of these nebula?, it may be that more than two million 

 years ago this mysterious body was extinguished in space. 

 Thus the history of the heavens traversing the night of 

 time passes through ages, and then appears to us like con- 



