31 G Prof. F. Zollner on the Temperature and 



We then have the following relation : 



lognatf&W ** (4) 



In order to connect this equation with the three previous ones, 

 a twofold hypothesis must be made : — 



(1) That the chief constituent of the solar atmosphere exert- 

 ing the pressure p a consists of the same gas which issues from 

 the interior of the sun during the activity of the eruption. 



(2) That the absolute temperature t of the atmosphere may 

 be supposed mainly to correspond with the absolute temperature 

 t a at the level of the point from which the gas issues. 



I consider that the first of these assumptions is sufficiently 

 proved by observation to allow of its use for the purposes of the 

 present memoir, inasmuch as the discovery of the chromosphere 

 has proved that the whole surface of the sun is surrounded by a 

 very considerable atmosphere of hydrogen gas. The admissibi- 

 lity of the second assumption I deduce from the fact that in 

 general the intensity of the light of the base of all the eruptive 

 prominences is not essentially different from that of the chro- 

 mosphere. 



Jf it be remembered that the constant mean temperature t in 

 formula (4) (which, owing to our ignorance of the law of decrease 

 of temperature, has been substituted for the temperatures sinking 

 to the elevation h) * must nearly coincide with that of the lowest 

 portions of the atmosphere, it will be seen that this temperature 

 must nearly approach that of the outer surface of the dividing 

 layer. 



According to the first supposition, the value p in the fourth 

 formula will become identical with the corresponding value in 

 formula (3) ; and according to the second supposition we have 

 t = t a . 



§2. 



Having in the foregoing stated the theoretical basis and the 

 most essential hypotheses upon which the phenomena under con- 

 sideration are to be treated, it will now be advisable to look to 



* With reference to the increasing density of the air as the lowest layer 

 is approached, the temperature expressed in formula (4) must, indepen- 

 dently of the particular law of diminution of temperature, always agree 



with that of a layer lying deeper than — . This difference, which, as a simple 



calculation shows, is generally very considerable, appears to me to have 

 been lost sight of in barometric measurements of heights where the mean 

 temperature of both stations has been used ; and this circumstance may 

 suffice to explain simply many periodic phenomena which have been lately 

 insisted on. 



