308 



THE GEOLOGIST, 



taciturnly regard the innovation, and thus give their appa- 

 rent assent. 



Now let us look to the operations of the Professor him- 

 self. We find his extended theory thus publicly adopted, 

 from the guarantee afforded by his own name ; — we find him 

 writing on the subject, and stating his ideas with equal cer- 

 tainty at no very distant period, and yet what has become of 

 the theory at this moment, in so far as concerns the light in 

 which it is to be viewed by the student of geology ? 



We find in letters addressed by him and M. Desor to the 

 Institute of France^ and from a friend, an eye-witness of the 

 transactions, that a party have ascended the glacier of the 

 Aar, and encamped at its summit in a small hut, to be hence- 

 forth known as the Hotel des Neufchdtelois,'' that they have 

 been engaged in boring through the ice, and inserting mea- 

 sured poles in order to ascertain the diminution in size 

 effected by the thawing of the upper stratum ; and we learn 

 that this has varied from seven to twelve feet in the course 

 of their short sojourn in those regions. Again we find 

 them boring through the ice, and introducing a coloured 

 liquid into the holes thus made, to test the porosity of the 

 glacier, and M. Desor records the fact that this colouring 

 matter required two hours to pass through a mass of ice 

 twenty feet thick and of great hardness — deducing from 

 this latter fact, that the porosity of the ice affords means for 

 the percolation of waters derived from the surface, which 

 undermine the glacier and contribute to its descent ; which 

 latter occurrence they prove by recording the advance of 

 the Hotel des Neufchatelois since Sept. 1841, of 207 feet, 

 and between the 11th and 2 3st July, 1842, of an additional 

 thirteen feet. 



These facts may be very serviceable to the developement 

 of natural processes ; but whether a glacier is porous or not, 

 is a matter of little moment to the geologist, and Professor 

 Agassiz should have been careful as to how he advanced the 



