THE SIDEREAL UNIVERSE. G99 



falling from the summit of heaven, would sink nine days 

 and nine nights through space before reaching the earth. 



How vastly the imagination of the poet of Bceotia is be- 

 low the truth, a truth which quite confuses one ! Indeed, 

 on one hand, physics prove that a solid body, falling by 

 gravitation during this space of time, would only traverse 

 143,000 leagues; whilst, on the other hand, the astronomy 

 of the nineteenth century teaches us that a ray of light is- 

 suing from Alcyone, the most brilliant of the Pleiades, takes 

 five years to traverse the intervening space before reaching 

 our eyes. And yet light is so rapid that in the tenth part 

 of a second one of its vibrations will pass round the globe. 

 But the depth of the heavens does not stop short at the 

 group of the Pleiades : on the contrary, they belong to its 

 nearer regions. 1 



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 re- 

 sources of our intellect would not suffice for such an at- 

 tempt. The space which light traverses in a year far out- 

 strips the measure of our perceptive faculties ; 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 eight minutes, eighteen seconds; and yet it is 



1 The Alpha of the Centaur, one of the nearest stars to us, which is only ahout 

 8,000,000,000 geographical leagues from the earth, sends us its light in three 

 years, and the pole-star, which is more than 70,000,000,000 leagues, in a quarter 

 of a century. 



