396 COSMIC PHILOSOPHY. [rr. u. 



exerted by the sun at the shorter distance. "But this newly- 

 added momentum is all needed to maintain the planet at its 

 new distance from the central mass, and can never be avail- 

 able to carry it back to the old distance. It is thus that 

 Encke's comet moves more and more rapidly as it approaches 

 the sun, into which it appears to be soon destined to be 

 drawn. For these reasons the earth, which now moves at 

 the rate of 18 miles per second, would attain a velocity of 

 379 miles per second when in the immediate neighbourhood 

 of the solar mass. Hence when at last the planet strikes 

 the sun, it must strike it with tremendous force. In a col- 

 lision of this sort, the heat generated by the earth and sun 

 alone would suffice to produce a temperature of nearly nine 

 million degrees Fahrenheit. Without pursuing the argument 

 into further detail, it is obvious that the integration of the 

 whole solar system, after this fashion, would be followed by 

 the complete disintegration of the matter of which it is con- 

 stituted. After the reunion of the planets with the sun, 

 the next stage is the dissipation of the whole mass into a 

 nebula. 



If we now go back for a moment to the beginning, and 

 ask what antecedent form of energy could have generated 

 the motion of repulsion which sustained our genetic nebula 

 at its primitive state of expansion, the reply must be that 

 nothing but a rapid evolution of heat could have generated 

 such a motion of repulsion. And if we ask whence came 

 this rapid evolution of heat, we may now fairly surmise that 

 it was due to some previous collision of cosmical bodies ; 

 arrested molar motion being incomparably the most prolific 

 known source of heat. Thus we get a glimpse of some pre- 

 ceding epoch of planetary evolution, from the final catastrophe 

 of which emerged the state of things which we now witness. 



We have here reached the very limit of scientific inference. 

 For note that, since the greater part of the potential energy 

 represented by the primitive expansion of our solar nebula 



