Atmosphere and the Earth, 237 



of the Gregorian October, and found that it was really the case ; 

 and now we have, from Bronner''s table, the mean temperature 

 for the Julian months March, April, September and October, 

 "calculated two and two, and the results viewed as the mean 

 temperatures of the Gregorian months of April and October. 



Temperature of the Earth in Kasan. 



The temperature of the earth is indicated by springs, which 

 issue forth in sufficient quantity and velocity, not to be af- 

 fected by the temperature of the air. The temperature of such 

 springs changes very little, and their changes are subject to dif- 

 ferent periods from those in the temperature of the air; the 

 maximum and minimum falls much later than in the corres- 

 ponding points in the temperature of the air. Springs, in moun- 

 tainous districts, seem not to give so certainly the temperature 

 of the earth as those in plains, because, in the former, we are 

 never certain that they do not take their origin at a considerably 

 greater elevation, and issuing forth at a lower point, mdicate a 

 lower temperature than belongs to the ground from which they 

 flow. As little can we select springs flowing to the surface from 

 marshy ground. 



It sometimes happens that the earth's temperature, in any place, 

 may be fixed with greater certainty, if springs, issuing at the 

 same time^om different points and kind of ground, shew a tem- 

 perature nearly the same, and almost uniform throughout the 

 whole year. 



