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Mr. J. N. Lockyer. 



[Nov. 23, 



(1.) If the terrestrial elements exist at all in the sun's atmosphere 

 they are in process of ultimate formation in the cooler parts of it. 



(2.) The sun's atmosphere is not composed of strata which thin 

 out, all substances being represented at the bottom; but of true 

 strata like the skins of an onion, each different in composition from 

 the one either above or below. Thus, taking the sun in a state of 

 quiescence and dealing only with a section, we shall have (as shown in 

 fig. 1) C say containing neither D nor B, and B containing neither 

 A nor C. 



Fig. 1. 



(3.) In the lower strata we have not elementary substances of high 

 atomic weight, but those constituents of all the elementary bodies which 

 can resist the greater heat of these regions. 



4. The conditions under which we observe the phenomena of the 

 sun's atmosphere have not, as a rule, been sufficiently borne in mind, 

 and it is quite possible that the notion of the strata thinning out has, 

 to a certain extent, been based more upon the actual phenomena than 

 upon reasoning upon the phenomena. 



5. Take three concentric envelopes of the sun's atmosphere, A, B, 

 (fig. 2), so that C extends to the base of A, and B also to the base of 

 A, that is, in both cases to the photosphere. Then, whether we deal 

 with the sphere or with a section of it, the lengths of the lines in the 

 spectrum of the strata 0, B, A will give the heights to which the 

 strata extend from the sun, and show where B and A respectively 

 thin out. As the material is by hypothesis continuous down to the 



