236 Intelligence and Miscellaneous Articles. 



note, 



Sa 9 = Sa + wfl* + Oa » or a — a* = ^ a* + ~- a*, 



we have 



V, ^ 1 • 007734-45 _1- 007714 = 



183960 



(Diaph. a) l-0077 34 - 45 -l'0077 14 = ^^rl-0077^ 



(Diaph. 6.) 1-0077 34 ' 08 -1-0077 H = jg^gg 1-0077* 



C - 0006516 -™) 1 ' 0077 ^ 



183960 



whence #=1355°, and 

 (Diaph. a) l-0077 34,45 -l-0077 )4 = ^g^gQ 1-0077^ 



+ 



f - 0009493 -!^)) 1 ' 0077 ^ 



+ 1 



(Diaph. c) l-0077 33 '7-l-0077 14 = jq^qq 1-0077' 



whence a: = 1353°. 



The agreement of the two values o£ x shows that the correction 

 necessitated by the radiation of the region of the sky in the vicinity 

 of the sun is made with sufficient exactness by writing for the total 



radiation of the different portions of this surf ace -q- ay , as if all 



these parts were at one and the same mean temperature y. 



Therefore, in the example selected, it will be concluded from these 

 calculations that, on the 20th June, at Grenoble, the temperature 

 of the sun, denned as I have indicated above, was, at 3 h 30 m , 



1354°. 



But this number itself, to give the true temperature of the sun, 

 ought to be further corrected on account of divers influences, par- 

 ticularly the absorption of the terrestrial atmosphere. It is chiefly 

 by operating at different altitudes, and (of course) noting the pres- 

 sure and the hygrometric state of the air at each station, that I 

 hope to solve this problem. For this purpose I have already made 

 several ascents of the Alps ; and I shall resume them as soon as 

 possible. — Comptes Rendus de VAcad. des Sciences, June 29, 1874. 



