Researches on Exuting Glaciers. 275 



as well as ourselves ; and I believe that in caldulating the 

 swelling at about 10 feet, we are far under the truth. It was 

 quite close to the place where, in the preceding year, I had 

 inserted two poles in the bores, the one to a depth of 9 feet, 

 and the other to a depth of 20, for the purpose of ascertaining 

 if the glacier really rejected foreign bodies. I burned with 

 impatience to discover what had become of my two poles. We 

 found both erect ; but having measured them, I ascertained 

 that they had been elevated 7 feet ; so that the longest was 

 only sunk to a depth of 13 feet, and the other would scarcely 

 stand in the hole, which was not more than a foot and a half 

 deep. The contact of the wood had also sensibly enlarged the 

 two holes, more particularly the second. 



At first sight the matter seems quite simple, and it might 

 be said that it was the level of the glacier which had 

 been lowered by the melting. But we must not forget that 

 these poles were planted on the portion of the glacier which 

 had become most swollen since the preceding year, and this 

 necessarily complicates the question, for how can we" conceive 

 at once a swelling of 10 feet and a lowering of 7 feet \ Abla- 

 tion had, nevertheless, actually taken place ; and if, notwith- 

 standing this ablation, the glacier became swollen as it pro- 

 gressed, that could only be because the augmentation of vo- 

 lume, resulting from the congelation of the water accumulated 

 in the interior of its mass, had been more considerable than 

 the volume of ice removed at the surface by the melting and 

 the evaporation. A similar occurrence ought to present it- 

 self whenever the summer is rainy, as in 1841, for then the 

 evaporation is less considerable, while an enormous mass of 

 water is infiltrated daily into the glacier. We found, in fact, 

 all the glaciers of the Oberland in a state of increase ; and in 

 all places they threatened to invade the pastures. 



The experiment which 1 have now mentioned was also 

 made by M. Escher de la Linth on the glacier of Aletsch ; and 

 the results he obtained were still more striking as to the ra- 

 pidity of the disappearance of the ice. M. Escher, with the 

 view of verifying the opinion 1 had expressed on the meta- 

 morphoses of glaciers, proceeded in the course of the month 



