CHAPTER XII 



THE EARTH 



If the enormous nebulae of space are but specks of 

 foam on the mighty ocean of the ether, our world 

 is less than a bubble of the foam. And yet the 

 world is large enough for us, and in some respects 

 it is an epitome of the Cosmos. We have scoured 

 space for millions, and millions, and millions of 

 miles, yet, if we except one or two unknown 

 nebular gases, we have found no atom that is un- 

 represented in the Earth. The law of gravitation 

 is exemplified as well by the Earth's orbit as by the 

 orbit of the most colossal star, and no doubt the 

 general process of cosmogony is seen as well in the 

 Earth's development as in the evolution of some 

 gigantic nebula. Anyhow, the Earth is to us the 

 most interesting of all the spheres, and we have 

 found out a good deal about it since the days when 

 it was supposed to be upborne by an elephant on 

 a tortoise, and since the days when it was believed 



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