ON THE SUN'S HEAT. 



371 



hundred and seventy-six thousand million million 

 million horse-power for three thousand years, and 

 at possibly a higher, certainly not much lower, rate 

 for a few million years. How is this to be ex- 

 plained ? Natural philosophy cannot evade the 

 question, and no physicist who is not engaged in 

 trying to answer it, can have any other justification 

 than that his whole working time is occupied with 

 work on some other subject or subjects of his 

 province, by which he has more hope of being able 

 to advance science. 



It may be taken as an established result of 

 scientific inquiry that the sun is not a burning fire, 

 and is merely a white-hot fluid mass cooling, with 

 some little accession of fresh energy by meteors 

 occasionally falling in, but of very small account 

 in comparison with the whole energy of heat which 

 he gives out from year to year. Helmholtz's form 



ether 2,000 years before chemists usurped the name for "sulphuric 

 ether," "muriatic ether," and other compounds, fancifully supposed 

 to be peculiarly ethereal ; and I trust that chemists of the present 

 day will not be angry with me if I use the word ether pure and 

 simple, to denote the medium whose undulatory motions constitute 

 radiant heat (or light). 



B B 2 



