RECENT SOLAR RESEARCHES. 95 



that, after all, Sir William Herscliel, without the aid 

 of spectroscope or polariscope, formed a juster view of 

 the solar constitution than any which has been recently 

 propounded. He was doubtless mistaken in the view 

 (which he put forward as a mere hypothesis) that the 

 real surface of the sun may be not very intensely 

 heated. We have every reason to believe that the 

 whole mass of the sun is raised to an inconceivable 

 degree of heat. But for the rest, there seems far more 

 reason to believe in Sir William Herschel's cloud- 

 layer theory than in any other which has been put 

 forward in recent times. 



Let us consider some of the consequences of such a 

 constitution. Imagine the ascent of vapors of many 

 elements from the fluid surface of the solar oceans. 

 This mixed atmosphere is in reality aglow with the 

 intensest heat and light, so that, if we could examine 

 its spectrum separately, we should see the bright lines 

 *of the various vaporous elements which constitute it. 

 But intensely hot as it is, it must yet be less hot than 

 the surface from which it has risen, because the forma- 

 tion of vapors is a process in which heat is used up. 

 And therefore, by a well-known law, the spectrum of 

 the light from the white-hot surface shining througli 

 the atmosphere will be a rainbow-tinted streak, crossed 

 by the dark lines corresponding to the various elements 

 composing that atmosphere. But as the lighter vapors 

 in this mixed atmosphere ascend, they reach a region 



