428 THE BEAUTIES OE NATURE cha^. 



lapse of time is a grander element in Astron- 

 omy even than in Geology, and dates back 

 long before Geology begins. We must figure 

 to ourselves a time when the solid matter 

 which now composes our Earth was part of 

 a continuous and intensely heated gaseous 

 body, which extended from the centre of the 

 Sun to beyond the orbit of Neptune, and 

 had, therefore, a diameter of more than 

 6,000,000,000 miles. 



As this slowly contracted, Neptune was 

 detached, first perhaps as a ring, and then as a 

 spherical body. Ages after this Uranus broke 

 away. 



Then after another incalculable period 

 Saturn followed suit, and here the tendencies 

 to coherence and disruption were so evenly 

 balanced that to this day a portion circulates 

 as rings round the main body instead of being 

 broken up into satellites. Again after succes- 

 sive intervals Jupiter, Mars, the Asteroids, 

 the Earth, Venus, and Mercury all passed 

 through the same marvellous phases. The 

 time which these changes would have re- 

 quired must have been incalculable, and they 



