12 FRAGMENTS OF SCIENCE. 



tencc, with these burning orbs ? To this question the man 

 of science, if he confine himself within his own limits, will 

 give no answer, though it must be remarked that in the 

 formation of an opinion he has better materials to guide 

 him than anybody else. He can clearly show, however, 

 that the present state of things may be derivative. He 

 can even assign reasons which render probable its deriva- 

 tive origin — that it was not originally what it now is. At 

 all events, he can prove that out of common non-luminous 

 matter this whole pomp of stars might have been evolved. 



The law of gravitation enunciated by Newton is, that 

 every particle of matter in the universe attracts every other 

 particle with a force which diminishes as the square of the 

 distance increases. Thus the sun and the earth mutually 

 pull each other; thus the earth and the moon are kept in 

 company ; the force which holds every respective pair of 

 masses together being the integrated force of their com- 

 ponent parts. Under the operation of this force, a stone 

 falls to the ground and is warmed by the shock ; under its 

 operation meteors plunge into our atmosphere and rise to 

 incandescence. Showers of such doubtless fall incessantly 

 upon the sun. Acted on by this force, w r ere it stopped in 

 its orbit to-morrow, the earth would rush toward, and finally 

 combine with, the sun. Heat would also be developed by 

 this collision, and Mayer, Helmholtz, and Thomson, have 

 calculated its amount. It w T ould equal that produced by 

 the combustion of more than five thousand worlds of solid 

 coal, all this heat being generated at the instant of collision. 

 In the attraction of gravity, therefore, acting upon non- 

 luminous matter, we have a source of heat more powerful 

 than could be derived from any terrestrial combustion. And 

 were the matter of the universe cast in cold detached frag- 

 ments into space, and there abandoned to the mutual gravi- 

 tation of its own parts, the collision of the fragments would 

 in the end produce the fires of the stars. 



