490 ON THE STRUCTURE OF GLACIER ICE 



But it is said that if cavities be made in the glacier and filled with 

 a coloured infusion, the latter will soon, by means of the capillary 

 fissures, infiltrate the surrounding mass. To determine this point, I 

 selected a spot upon the north wall of a crevasse, just opposite the 

 Montanvert, and between the centre and the west shore of the Mer de 

 Glace, where the veins were well developed, their planes having a 

 general north and south direction, but dipping at an angle of about 

 70° towards the centre of the glacier. On the northern aspect of the 

 ice I cut away the superficial layer, so as to form two faces of a cube 

 of about a foot in the side on the deep ice. One of these faces looked 

 westward, and was consequently nearly parallel to the cleavage ; the- 

 other looked northward, and was therefore nearly perpendicular to it. 

 Perpendicular to the west face, and therefore to the structural planes, 

 I bored a hole with an auger, about an inch in diameter and 9 inches 

 long, and just sufficiently inclined to the horizon to hold the infusion 

 of logwood, with which I filled it. I then thinned away the north 

 face of the cube very carefully until the north wall of the hole was less 

 than 2 inches in thickness — until, in fact, I could see the dark fluid 

 through the substance of the several blue veins which it traversed with 

 perfect distinctness. 



For two hours not the slightest trace of leakage or infiltration into 

 the substance of the ice forming the walls of this cavity could be 

 observed ; and the contour of the contained liquid remained perfectly 

 sharp and well defined. It then began to leak at one point near its 

 upper end through a small crack in the wliite ice, which led directly 

 outwards. The liquid spread neither up nor down in the crack Four 

 hours afterwards no change whatever had taken place in the liquid 

 contained in the lower part of the hole. At this time you joined me 

 upon the ice, and you will recollect that I carefully thinned away the 

 wall with a sharp knife until in some parts it was not more than \ of 

 an inch thick. Still no infiltration occurred. The knife at length acci- 

 dentally penetrated the wall, and the liquid at once flowed out. I then 

 poured some clean water through the hole, and all trace of the coloured 

 infusion was at once so thoroughly removed, that, on cutting away one 

 wall, the other appeared perfectly clean and of its natural aspect. 



I have given the details of this one experiment in order to show 

 in what manner all were made ; but it is unnecessary to be equally 

 prolix with regard to the others. Suffice it to say, that, whether the 

 holes were bored perpendicular to the structure or paralleh with it, or 

 at any intermediate angle, whether in white ice or in a blue vein, the 

 result was precisely the same, not a particle of fluid making its way 

 into the surrounding substance of the ice along the veins, nor in most 



