THE ECLIPSE OF 1871. 1 03 



graphed all these must be regarded as marking 

 noteworthy epochs in the progress of eclipse researches. 

 But not one of them surpasses, or perhaps equals in 

 importance, the eclipse of last December, when, for the 

 first time, the wonderful complexity and magnificence 

 of the solar surroundings were clearly revealed. 



Already in these pages the progress of solar research 

 has been described with considerable fulness of detail ; 

 and, in particular, those questions respecting the solar 

 coroaa which have for the last two years been 

 earnestly discussed by astronomers have been dealt 

 with at length. It will, therefore, be desirable to 

 consider in this place, not the progress and deve- 

 lopment of our knowledge respecting the sun, but 

 the actual position of such knowledge now, when, 

 chiefly in consequence of the observations made during 

 the late eclipse, we are able to speak with some de- 

 gree of confidence respecting the nature of those 

 regions which lie around the luminous centre of the 

 planetary system. 



Of the actual nature of that intensely hot and 

 brilliant surface which the sun presents to our study, 

 I can say but little. Astronomers are not certain 

 even whether it is liquid or gaseous, and at present 

 their ideas respecting the intensity of its heat are in 

 most unsatisfactory disagreement. On the one hand 

 we have a theory by Father Secchi, the eminent Italian 

 astronomer, according to which the heat of the sun's 

 surface is certainly not less than ten million degrees 

 Centigrade, or some eighteen million degrees of the 



