80 Evolution 



condensing mass, and the heavier gases and vapours 

 would rest between the two. A miniature sun would be 

 the outcome of this arrangement. Above the ocean of 

 molten metal floated the various gases that would one 

 day form the ocean and the atmosphere, holding in them 

 masses of carbon and different salts. They would to- 

 gether form an atmosphere with a pressure on the 

 molten planet 250 times as great as that of the actual 

 atmosphere, and the intense outpouring of heat into 

 space would cause storms that would lash up the molten 

 metal in fiery eruptions and send out the red-hot 

 atmosphere in gigantic flames. This is merely to say 

 that our earth passed through the phase in which we 

 find the sun to-day. 



The next chapter of importance in the story of the 

 earth was its giving birth tg the moon. Since it was a 

 small nebula, or semi-nebulous body in a state of 

 condensation, it may be imagined as parting with masses 

 of its material, as its own parent-nebula had done. But 

 there was now a new force at work: tidal action. The 

 vast mass of the sun, 92 million miles away, must have 

 had on the liquid earth the effect which we see the moon 

 to have to-day on its liquid oceans. Our earth was then 

 rotating on its axis — the very process of cooling would 

 lead to this rotation — five or six times faster than it now 

 does, and a great bulge or tidal wave was raised at the 

 point opposite the sun. Under the enormous strain on 

 the liquid planet, a mass of 73 trillion tons was detached 

 from it, and continued to circulate round it at the 

 original speed. This mass of matter rounding into a 

 ball in the familiar way, moving slowly out until it 

 reached 240,000 miles from the earth, revolving always, 

 but with increasing slowness, round the parent earth, is 

 the solidified sphere to which we give the name of the 

 moon. 



