162 Prof. BischofF on the Temperature of 



observation at the foot of the Mettenberg, b the point of obser- 

 vation in the Grindelwald, ab the horizontal line, Fig. cdb 

 profile from the glacier of the Grindelwald, ed the chthoniso- 

 thermal line of 39°.31 Fahr., a.ndj'gb the chthonisothermal line 

 of 43°.77 Fahr. 



From these observations' it is evident, that the cooling influ- 

 ence of glaciers on the soil in their vicinity is not felt to any 

 great distance ; but that it is soon counteracted by the heat of 

 the air. This accounts for the remark so often met with in de- 

 scriptions of travels, that flowers and strawberries maybe gathered 

 within sight, nay in the immediate neighbourhood, of the glaciers. 



The mean temperature at the glaciers is about the same as 

 that of Barnaul, in Asiatic Russia, 53°, 20' N. Lat. ; that at the 

 foot of the Mettenberg is about equal to that of Moscoto, 55° 

 47' N. Lat. ; or to that of Drontheim, 63° 26' N. Lat. ; and at 

 Grindelwald it is about the same as at Konigsberg in 54° 42' 

 N. Lat.* Such various mean temperatures and such various cli- 

 mates are, therefore, crowded together in the vicinity of that 

 glacier. 



The observations and experiments which have formed tlie 

 subject of this chapter, answer the question, whether the increase 

 of temperature towards the centre of the earth follows the same 

 law, departing from all points situated on the same level, in the 

 negative. The experiments have also made us acquainted with 

 the chthonisothermals, lines of equal temperature, which, rigor- 

 ously speaking, only remain parallel with the surface in plains 

 within a very limited space, but bend upwards under moun- 

 tains, and suffer a depression under lakes, seas and glaciers ; 

 thus always forming a greater or less angle with the horizon. 

 Besides this, they must be a function of the curvatures found by 

 Von Humboldt in the isothermal lines ; for just as little as these 

 coincide with the latitudinal lines of the earth,t will also the 

 points of equal temperature in the interior of the earth be situa- 

 ted at equal depths in the same latitudinal circle. 



I will conclude this chapter with an application of the fact, 

 that the chthonisothermal lines curve upwards in mountains, to 



' Kamtz Lehrbuch der Meteorologie, ii. 

 t Schweigger's Journal, xxv. 201. 



