157 



Cavern of Ice, which is at 1728 toises, conse- 

 quently below the limit of the perennial snows 

 under this zone. It is probable, that the cold 

 which reigns in this cavern is owing to the same 

 . causes, which perpetuate the ice in the crevices 

 of Mount Jura, and the Apennines, and on which, 

 the opinions of naturalists are still much divid- 

 ed*. This natural ice-house of the Peak has ne- 

 vertheless none of those perpendicular openings* 

 which give emission to the warm air, while the 

 cold air remains undisturbed at the bottom. It 

 seems that the ice is preserved in it on account 

 of it's mass, and because it's melting is retarded 

 by the cold, which is the consequence of quick 

 evaporation. This small subterraneous glacier 

 is situate in a region, the mean temperature of 

 which is probably not under three degrees ; and 

 it is not, like the true glaciers of the Alps, fed 

 by the snow waters that flow from the summits 

 of the mountains. During winter, the cavern is 

 filled with ice and snow ; and as the rays of the 



* Saussure, Voyage dans les Alpes, § 1406 — 1414. Pre- 

 vost, du Caloriqne rayonnant, p. 409 — 422. In the greater 

 part of the cellars of ice, for instance that of St. George, be- 

 tween Niort and Rolle, a thin lajer of limpid ice forms itself 

 in summer on the walls of the calcareous rock. Mr. Pictet 

 observed, that at this epocha the thermometer does not des- 

 cend, in the air of the cellar, below two or three degrees, so 

 that we must attribute the congelation to a local and very 

 rapid evaporation. 



