460 FRAGMENTS OF SCIENCE 



competent to generate an amount of heat equal to that 

 obtainable from the combustion of 6,000 times the weight 

 of the earth of solid coal. With the quickness of genius 

 he saw that we had here a power sufficient to produce 

 the enormous temperature of the sun, and also to account 

 for the primal molten condition of our own planet. Mayer 

 shows the utter inadequacy of chemical forces, as we 

 know them, to produce or maintain the solar temperature. 

 He shows that were the sun a lump of coal it would be 

 utterly consumed in 5,000 years. He shows the difficul- 

 ties attending the assumption that the sun is a cooling 

 body; for, supposing it to possess even the high specific 

 heat of water, its temperature would fall 15,000 in 5,000 

 years. He finally concludes that the light and heat of the 

 sun are maintained by the constant impact of meteoric 

 matter. I never ventured an opinion as to the truth of 

 this theory; that is a question which may still have to 

 be fought out. But I refer to it as an illustration of the 

 force of genius with which Mayer followed the mechan- 

 ical theory of heat through all its applications. Whether 

 the meteoric theory be a matter of fact or not, with him 

 abides the honor of proving to demonstration that the 

 light and heat of suns and stars may be originated and 

 maintained by the collisions of cold planetary matter. 



It is the man who with the scantiest data could ac- 

 complish all this in six short years, and in the hours 

 snatched from the duties of an arduous profession, that 

 the Eoyal Society, in 1871, crowned with its highest 

 honor. 



Comparing this brief history with that of the Copley 

 Medalist of 1870, the differentiating influence of "envi- 

 ronment," on two minds of similar natural cast and en- 



