714 THE UNIVERSE. 



only at a period far distant in the future, for^ according to 

 the experiments of Bischof, 9,000,000 of years would be re- 

 quired to lower the temperature of the earth only fifteen 

 degrees. 



CHAPTER III. 



THE MOON. 



THIS sole and faithful satellite of the earth, formed by a 

 fragment detached from it, now cold and wan, rolled round 

 us, when it began, a red and blazing sphere, vomiting tor- 

 rents of fire from its whole surface. Whilst gravitation was 

 regulating its form and path, the moon, in the course of 

 thousands of years, gradually exhausted its fires, to show us 

 at last its pale and silvery face, the sad luminary of our 

 nights, the splendid nocturnal mirror which reflects to us, 

 pale and cold, the divergent rays of the sun. 



Compared to the immeasurable distances of the nebulse 

 and stars, the space which separates us from our satellite is 

 quite insignificant ; she is our next-door neighbor, and the 

 eye can so clearly discern her form and peculiarities that 

 she seems almost to touch us. But this insignificant dis- 

 tance, abstractly considered, is yet vast enough. The dis- 

 tance from the earth to the moon is about 237,000 miles. 

 If it were possible to get there by means of steam, it would 

 require 1 year and about 322 days for a locomotive, start- 

 ing from our globe and travelling at a high rate of speed, to 

 reach the moon and land its passengers. A heavy body pro- 

 jected from the lunar orbit would, it is true, reach us much 



