( 589 ) 



The results which I have obtained for the differences : 

 L s = Ivory — table of temperatures 



are the following: 



TABLE III. 



To test the computations, we may compare the mean of the values 

 of As for the four seasons, and the values of Ls in column (i 

 which have been computed, independently the former, for the mean 

 yearly temperatures, which are almost equal to the mean of the 

 temperatures in the four seasons. Only for z = 89°40' and 2 = 90° 

 do these values show deviations exceeding 0".l. 



From table III follows, 1 that for a distribution of temperature, 

 as derived by me from observations, the refraction deviates percep- 

 tibly from that deduced from Ivory's theory, 2 that the differences 

 in the refraction in the different seasons are about of the same order 

 as the deviations themselves. I want it to be distinctly understood, 

 1 that the adopted distribution of temperature above 13 kil. and 

 especially from 16 to 18 kil. is uncertain, and 2 that I have not 

 taken into account the refraction in the layers which are lying more 

 than 18 kil. above the surface of the earth, in other words those 

 layers where the density, as compared to that of the surface of the 

 earth, is less than 1 — (),95 3 , or less than 0,0975. 



