A Study in the Natural History of Ice 293 



I confined myself to the natural cave or Antmm, from which 

 the glacier stream proceeds, and left the artificial grotto 

 maintained for the delectation of the summer visitors on one 

 side. I had a feeling, which I imagine was not quite peculiar 

 to myself, that the use of this pleasure-grotto for scientific 

 purposes would be a little infra dignitatem of the student. 

 However, one or two visits to it convinced me that the 

 artificial grotto was the only place where the study of glacier- 

 ice in its primary state was possible. Having arrived at this 

 conviction, the economic reasons for the construction and the 

 maintenance of the grotto troubled me no more. I reflected 

 that if an astronomer can legitimately accept and use an 

 observatory furnished by one millionaire, the humble student 

 of glacier-ice may use as his laboratory the grotto maintained 

 by the subscriptions of, it may be, a million tourists. 



Intergranular Melting of Tee and Freezing of Medium. 



If the ice in the interior of the grotto in a glacier be 

 studied in summer it will be perceived that melting does not 

 take place exclusively at the surface ; the interior of the ice 

 appears to be wet also. The internal ice receives heat from 

 withput only by conduction, which suffices for the main- 

 tenance of intergranular moisture. The only other source 

 from which it can obtain heat is the transformation of work. 

 Helmholtz mentions this as a possible source of heat available 

 for the fusion of ice in the interior of a glacier. He says 1 : 

 " I should like here to direct attention to the fact that a not 

 inconsiderable amount of heat due to friction must be pro- 

 duced in the larger glaciers. In fact calculation shows that 

 when a mass of ne"ve" descends from the Col du Gfant to the 

 source of the Arveyron, it is possible for one- fourteenth part 

 of it to be melted by the heat produced by the mechanical 

 work." 



The heat which can be obtained from both of the above 

 sources is insufficient to produce any considerable liquefaction 

 of the ice as a whole. Nevertheless the intergranular moisture 



1 Populiire Vortriige. Braunschweig: Vieweg, 1865, p. 133. 



