358 Prof. Bischof o?i the Temperature of 



Mount Helvellyn, near Kendal, 2700 feet above the sea, and 

 S93 feet below the summit of the mountain, on the 27th Au- 

 gust, to be 38^ So low a temperature for a spring rising in 

 such a moderate elevation, in the north of England, is somewhat 

 remarkable. 



Von Humboldt* likewise mentions several springs in the 

 mountains of Cumana and Caraccas, whose temperature is much 

 lower than might be expected from their elevation. Hunter^s 

 ■well-known observations on the temperature of springs in Ja- 

 maica, afford examples of similar appearances. Humboldt al- 

 ready observed that one of those springs, rising at a height of 

 3918 feet above the sea, probably derives its very low tempera- 

 ture from the peak which rises to 6966 feet. 



That even waters flowing on the surface of the earth, and 

 bearing a temperature very different from that of the atmosphere, 

 change their temperature but very slowly, is particularly evident 

 from the brooks which issue from the glaciers, and which fre- 

 quently, after a long-continued course, suffer a scarcely percep- 

 tible increase of temperature. On the western declivity of the 

 Teutoburger Wald, where such copious springs occur that they 

 immediately form considerable rivers, I also found that one of 

 these rivers, after a course of half a mile, had only become 

 0°.675 warmer, although the temperature of the air was 22°.5 

 higher than that of the water. 



All these observations shew that springs which descend from 

 great heights bring down cold with them, and indeed the more 

 copious they are, the quicker their subterranean course, the 

 steeper the mountains, or the nearer their channels approach the 

 vertical position, and the less they are adulterated on their way 

 with waters of a different temperature, the greater is the degree 

 of cold which accompanies them. From which it follows, con- 

 versely, that springs which rise from below, out of various strata 

 of the earthy will bring heat with them, and in a great degree 

 the more the above conditions are fulfilled. 



The more the temperature of springs surpasses that of the 

 strata through which they pass, the more they will lose of their 

 temperature. Boiling springs seem only to reach the surface, 



• Gilbert's Annal. vol. xxiv. p. 46. 



