164 HEAT OE HIGHER LAYERS OF AIR. 



ground (at least of all great glaciers that descend 

 in valley-channels) is in a state of uninterrupted 

 thaw. This is proved by actual observation in all 

 places where it has been possible to get under- 

 neath the glacier. Under many glaciers caverns 

 run up inwards, between the bottom and the ice, to 

 a great length, and branch out into many channels. 

 Hugi, Ennemoser, and others* penetrated far up, 

 and crept about under several of these caverns. 

 The ice-vaults, from under which the brooks run 

 at the lower end of many glaciers, are universally 

 known. That these hollows also exist in the upper 

 parts of the glaciers is proved by the little rivulets 

 which even there fall down into the crevices, and 

 whose murmur, as they run on under the ice, may 

 be perceived in many places. When spring sets 

 in, water collects above in many of the holes and 

 crevices, and forms the so-called glacier-pools, 

 which often he high upon the glacier, until at last 

 they find entrance into the crevices of the interior, 

 and then they generally are drained in a short time, 

 and a sudden swelling of the glacier-stream is the 

 result. 



* The innkeeper, Christian Bohren, fell in the year 

 1787, on the upper Grindelwald glacier, into a crevice 

 sixty-four feet deep, from which, in spite of his broken 

 arm, he managed to escape, by creeping in the bed of the 

 stream, under the glacier. 



