16 SCIENCE IN SHORT CHAPTERS. 



sociated gases a nucleus of some kind, we are hypothetic- 

 ally supplied with the main conditions which I suppose to 

 exist in the sun. 



A little reflection upon the application of the above- 

 stated laws to these conditions will show that the stupen- 

 dous ocean of explosive gases would constitute an enormous 

 stock of fuel capable, by its combustion, of setting free ex- 

 actly the same quantity of heat as had previously been con- 

 verted into decomposing or separating force ; the amount 

 of combustion would always be limited by the possible 

 amount of radiation, and the radiation would again be lim- 

 ited by the resisting envelope of aqueous vapor produced by 

 this combustion. 



If these conditions existed in a perfectly calm and undis- 

 turbed solar atmosphere, there would be a continally in- 

 creasing external envelope of aqueous vapor, and a contin- 

 ually diminishing inner atmosphere of combustible gases ; 

 there would be a gradual diminution of the amount of solar 

 radiation, and a slow and perpetually retarding progress 

 towards solar extincton. 



It should be noted that, according to this explanation, 

 the supply of heat is originally derived from atmospheric 

 condensation due to gravitation, that the storage of surplus 

 heat is effected by dissociation, and its evolution mainly by 

 recombination or combustion. 



The great difficulty, that of the perpetual renewal of the 

 solar fuel, still remains unsolved ; the fact that during the 

 millions of years of geological history we find no indications 

 of any declining average of solar energy is so far still unex- 

 plained by this, as by every other, attempt to account for 

 the origin of solar and stellar light and heat. 



In his inaugural address to the British Association Meet- 

 ing of 1 866, Mr. Grove put the following very suggestive 

 question: " Our sun, our earth, and planets are constantly 

 radiating heat into space ; so, in all probability, are the 

 other suns, the stars, and their attendant planets. What 

 becomes of the heat thus radiated into space ? If the uni- 

 verse has no limit and it is difficult to conceive one there 

 is a constant evolution of heat and light ; and yet more is 

 given off than is received by each cosmical body, for other- 



