856 Prof. BischofF 07i the Temperature nf 



their becoming deeper during the warm seasons, by the sinking 

 of the particles of water, which have been warmed by the warm 

 air at the surface, into the ice, by which the ice is melted away 

 in a perpendicular direction. The lioles seem, however, to owe 

 their first existence, as Ebel* observes, to stones, which become 

 heated by the sun to a greater degree than the surrounding ice, 

 melt away the ice around them, and thus penetrate into the gla- 

 cier. And, in fact, whenever I have been able to see to the 

 bottom of such holes, I have invariably discovered one large or 

 several small stones. It is evident that these stones can only 

 continue to sink deeper into the ice, so long as the summer lasts, 

 lor after the water in them has become frozen during the fol- 

 lowing winter, the conditions necessary for the further sinking 

 of the stones in the ensuing summer can no longer exist. On 

 the contrary, the melting of the ice from the surface, gradually 

 brings the stones out again. This sinking and reappearing of 

 the stones may be continually repeated, until they reach the 

 lower extremity of the glacier, or are precipitated into clefts, 

 which extend to the bottom of the glacier. In this manner the 

 stones may, by the sliding of the glacier, be made to perform a 

 journey en cchdons.-f 



As these holes in the ice never reach the bottom of the gla- 

 cier, and as the water which falls into the clefts is never above 

 32°, it is not possible that the water, which filters down from 

 the surface to the bottom of the glacier, should come there with 

 a temperature higher than 32°.0, which they have when they is- 

 sue in streams from the lower end of the glacier. We are, 



• Loco citato, part iii. p. 117. 



-|- This seems to me to account very plainly for another phenomenon, 

 namely, since the glacier consists of a mass of snow irregularly intermixed 

 with frozen water, and is consequently granular opaque, and very different 

 from ice formed by the freezing tjf stagnant water, we ought to be able to 

 distinguish, that ice which was formed by the freezing of the water in holes in 

 the glacier, from the rest of the mass of the glacier. But Escher remarks, that 

 not one of the philosophers who have exjilored the Alps has been able to make 

 such a distinction. (See Gilbert's Annals, Ixix. 118). It is, however, evi- 

 dent, that it must be equally impossible to find any of the ice formed in the 

 clefts of the glaciers, at the lower extremity, as to find the stones, because, 

 when these reappeared at the surface, the ice by which they had been covered 

 must necessarilv have been melted awav. 



