THE PHOTOSPHERE AND SUN-SPOTS, 533 



when fuel is supplied to it. The sun was, then, to the ancient world, 

 a kind of supernatural phenomenon, interest in which partook more 

 of the uninquiring awe due to an immediate miracle of Deity, than of 

 the curiosity excited by a fact of the natural world ; and whatever we 

 may think of such a way of regarding the matter, the view of the 

 ancient philosophy, that the sun was an immaculate orb of pure fire, 

 self-sustained, continued to be accepted almost as a dogma of the faith 

 down to times subsequent to the dawn of the modern philosophy. 



When one of the first, possibly the first, of the observers of sun- 

 spots, Christopher Scheiner, a Jesuit, communicated his discovery to 

 his provincial, the latter, Mr. Proctor relates, answered : " I have read 

 Aristotle's writings from beginning to end, many times, and I can as- 

 sure you I have nowhere found in them any thing similar to what you 

 mention ; go, therefore, my son, tranquillize yourself, be assured that 

 what you take for spots in the sun are the faults of your glasses or 

 your eyes." 



Perhaps we are, however unconsciously, ourselves in some degree 

 Aristotelians in such matters, and it is at least certain that the un- 

 recognized influence of ancient modes of thought has delayed progress 

 in solar physics, by preparing astronomers to admit theories which they 

 could not have accepted with a clear recognition of the fact that physi- 

 cal laws are the same in the sun as here, however erroneously we learn 

 them from our limited terrestrial experience. In the hypothesis of 

 Wilson, for instance, that exhaustless flow of solar light and heat is 

 made to come from a shallow stratum of brilliant cloud, surrounding 

 a dark and presumably cold and solid globe. The elder Herschel 

 adopts this hypothesis, with slight modification (it is not yet quite 

 dislodged from the text-books), "and even his eminent son appears to 

 feel nothing like an imperious demand for a sustaining cause of the 

 almost infinite flood of heat his own researches showed that these 

 clouds must be giving. 



It seems now extraordinary that men justly eminent as the Her- 

 schels could rest satisfied with an hypothesis which so evaded the 

 consideration of the fundamental problem of the equality of the solar 

 radiation, by tacitly assuming the suspension there of the most famil- 

 iar laws of terrestrial experience. 



The views now generally accepted contemplate the sun as hot 

 throughout its mass, and in such a mass as containing indubitably an 

 enormous though finite reservoir of heat. And, if, so far at least, 

 there is an agreement even among those who diff*er as to the way in 

 which this heat originated and is maintained, much is due to astrono- 

 mers like Faye, who have insisted on this recognition of the need of 

 accounting for the equable emission of heat with a success which may 

 make us underrate our obligations to them, as this need, once enun- 

 ciated, is so clear as to seem a truism, though it was far from being 

 such till a very recent period. 



