COSMIC PHILOSOPHY 



secondary, move in elliptical orbits of small or 

 moderate eccentricity. 



We are so accustomed to acquiesce in these 

 facts, as if they were ultimate, that we seldom 

 stop to consider them in their true light, as un- 

 impeachable witnesses to the past history of the 

 solar system. Yet as Laplace has shown, it is 

 practically impossible that such harmonious re- 

 lations should hold between the various mem- 

 bers of the solar system, unless those members 

 have had a common origin. 



The clue to that common origin may be 

 sought in facts which are daily occurring before 

 our very eyes. Every member of our planetary 

 system is constantly parting with molecular mo- 

 tion in the shape of heat. Our earth is inces- 

 santly pouring out heat into surrounding space ; 

 and, although the loss is temporarily made good 

 by solar radiation, it is not permanently made 

 good, — as is proved by the fact that during 

 many millions of years the earth has been slowly 

 cooling. I do not refer to the often-cited fact 

 that the Arctic regions were once warm enough 

 to maintain a tropical vegetation ; for this high 

 temperature may well have been due to minor 

 causes, such as the greater absorptive power of 

 the ancient atmosphere with its higher percent- 

 age of carbonic acid and ozone. Nor need we 

 insist upon the alleged fact that extensive glaci- 

 ation appears to have been unknown until a 

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