S66 Prof. Biscliof 071 the Temperature of 



1834 a great number more in that neighbourhood ; and, on similar 

 grounds, I think that I am justified in considering the majority 

 of them as thermal. 



In mountains which are split to a great depth, it is therefore 

 possible that scarcely one spring may be found from which the 

 temperature of the soil might be determined. And, even when 

 such is not the case, an approximative idea of the mean tempe- 

 rature of the soil can only be obtained, provided there be no 

 high mountains near, by observing the temperature of a great 

 number of springs in the neighbourhood for at least a year, and 

 taking the coldest among them. 



So long, however, as no springs are found whose differences 

 of temperature are in totally different proportions from those in 

 the table, a tolerably correct value may be found for the mean 

 temperature of the soil, from observations on the temperature 

 of single variable springs, if made at a well chosen season, and 

 provided they do not rise out of unusually fissured rocks. For 

 instance, since the mean temperature of springs generally falls 

 in the months of December or January, and in June or July, 

 it is sufficient to observe the temperature of springs only at those 

 times, in order to get a very near approximation to the actual 

 mean temperature of the soil. It may be ascertained still more 

 exactly, by finding out exactly the period of the maximum or 

 minimum of the springs, and observing their temperature three 

 months after that date. The precise period of the mean tem- 

 perature of springs for each individual case, cannot be deter- 

 mined with such exactitude, as it was for the mean temperature 

 of the air, by the observations made at Leilh in Scotland.* 



The same objections which we have made to Wahlenberg''s 

 determinations of the mean temperature of the soil, are also ap- 

 plicable to the observations of Kupffer-f- in several parts of east- 

 ern Russia, as well as to the conclusions which he was led to 

 draw from them. 



Erman jun.J finds the temperature of the springs at Konigs- 

 berg 3°. 55 higher than that of the atmosphere. I can only ac- 



• Results of the Therm. Obs. made at Leith Fort every hour of the day 

 and night during the years 1824 and 1825, p. 19. 



"I" Poggendorf 8 Annalen, vol. xv. p. 159, and following. 

 ^ t Poggendorf *s Annal. vol. xi. p. 310. 



