292 Report of the Researches of 31. Agassiz, 



diameter, was bored directly above the gallery, to the depth 

 of five feet ; into this, at mid-day, was poured five quarts 

 (litres) of the infusion of logwood, which all disappeared in 

 half an hour. We had no doubt about the result of our ex- 

 periment, for the presence of the capillary net- work travers- 

 ing the entire mass, was now no longer an hypothesis, as the 

 quantity of water infiltrating from the sides of the gallery was 

 a clear demonstration to our senses. In spite, however, of 

 this, it was with much joy that we received the information, 

 two hours and a half after the introduction of the infusion, 

 that it had appeared on the roof of the gallery. We all be- 

 took ourselves to the spot, where we clearly saw, at the upper 

 angle of the roof, a large marking of a beautiful yellow colour, 

 which could only have- been produced by the infusion of the 

 logwood. Presently we observed the spot enlarge downwards 

 and laterally. We attentively observed the manner of its pro- 

 pagation, and perceived that the coloured water insinuated 

 itself into all the fissures, advancing very much per saltern. 

 In removing, with a hatchet, a part of the coloured portion, 

 we distinctly observed that the colour pervaded only the capil- 

 lary fissures, and that the icy interspaces were themselves 

 quite colourless. After some hours, the tinting had reached 

 as far as the floor of the gallery, and was descending deeper 

 and deeper. Thus we had a convincing proof that the capil- 

 lary fissures are a phenomenon not of the surface only, since 

 they exist at depths where external agents exercise no influ- 

 ence, and that most probably they extend through the entire 

 mass of the glacier. 



These infiltration experiments were often repeated, and 

 always with the same results, the coloured liquid usually reach- 

 ing the roof of the gallery in less than two hours. Whilst nar- 

 rowly examining the circulation of the liquid in the interior 

 of the ice, we were led to many observations upon the modi- 

 fications and variations in the capillary fissures themselves, 

 which, in general, are much larger than is usually supposed. 

 We also noticed that the podurellw or ice-fleas {Desoria glacU 

 alis, Nic.) readily found their way into them. We discovered 

 these insects in the gallery the very day it was opened, and 

 we often saw them moving freely about in the interior of the 



