1847.] OBSERVATIONS ON THE AAR GLACIER. 207 



The observations of M. Dollfuss, which will, without doubt, be 

 published one day in detail, have proved the contrary, and have 

 shewn that a glacier, like a semifluid body, urged by a mechani- 

 cal force, moves on without being influenced by the state of the 

 surrounding medium"* 



Now, Sir, the last passage, the italics of which are in the 

 original, conveys to us, in the first place, the pleasing informa- 

 tion that M. Collomb, and probably M. Dollfuss also, have ac- 

 cepted the viscous theory of glacier motion. The word " semi- 

 fluid" applied to a glacier, is now, notwithstanding its seeming 

 harshness, an adopted word. But I must enter an earnest pro- 

 test against the supposed discovery of the uniformity of the 

 motion and its entire independence of atmospheric circumstances, 

 being assumed to add any probability to the viscous theory, as 

 the phraseology of the preceding extract seems to infer. On 

 the contrary, if there be any glacier which does not present the 

 law of variable velocity, which I established for the first time, 

 on the Mer de Glace of Chamouni in 1842, and which has since 

 been found on the Glacier of Bossons, on the Glacier of Grin- 

 del wald, and was supposed to have been found on the Lower 

 Glacier of the Aar, such a glacier affords a proof the less in 

 favour of viscous or semifluid theory. 



It is on this account, Sir, that I desire that the readers of 

 the scientific journals may be made fully aware of the amount of 

 the evidence by which, in some glaciers at least, the direct con- 

 nection between the movements of the glacier and the condi- 

 tions of temperature and moisture have been established ; and 

 it is for this object that I crave a few pages of your Journal, 

 for an extract from a more elaborate and less accessible paper. 



Before quitting the subject, I wish to add, that I concur 

 with M. Collomb in desiring the full publication of M. Doll- 

 fuss' results on the Glacier of the Aar, which, latterly at least, 



* Bibliotheque Universelle publiee 15 Decembve 1846, p. 212, note. The pas- 

 sage in italics stands thus in the original, " Un glacier comme un corps semifluide 

 pousse par une force mecaiiique, marcJieen avnnt nans se laisser inflwncer par Vetat 

 du milieu ambiant.^ 



