268 Ice and its Natural History 



regarding the melting of glaciers, I entered the antrum and 

 bored a nearly vertical hole, about 12 centimetres deep 

 and i^ centimetres wide, in the ice of the eastern wall. 

 It was within a metre of the entrance, but so situated that 

 the water produced by the melting of the surface ice, which 

 poured over the entrance, could not reach it. 



Although everywhere there appeared to be melting, the 

 hole remained empty and dry ; even the snow-turnings which 

 remained in the hole were quite dry. It was still perfectly 

 dry when I left the glacier at 6 p.m. When I visited it again 

 the next day at 3.45 p.m., it was still perfectly dry. The 

 stream flowing out of the antrum was so voluminous that it 

 was impossible to explore it that afternoon. The next day, 

 however, the I5th, at 11 a.m., the volume of water was small, 

 and it was possible to penetrate into the antrum. It ran into 

 the ice in a straight line for 21 metres, and terminated in a 

 rock 2 metres high by 3 metres broad, which filled the whole 

 area of the cavern. 



Grooving of Ice by Rock. While making these measure- 

 ments, my attention was arrested by an appearance on the 

 roof of the cave, close to where the top of the rock bore 

 against the ice. From the line of contact, and for a distance 

 of about half a metre towards the entrance, the ice was deeply 

 scored and grooved. At first I could hardly believe it; but 

 there was no doubt about it. Although I had often heard of 

 glacial action, the idea of glacial reaction had never occurred 

 to me, still less had I ever expected to witness it. The 

 experience that in an auger-hole bored in the ice within a 

 metre of the entrance, and in very hot weather, the delicate 

 ice-turnings which were left in it remained unmelted for at 

 least twenty-four hours, made it no longer wonderful that 

 the surface of the ice at a distance of 20 metres further 

 from the entrance should remain unmelted long enough to 

 show the effect on it of the rock over which, on evidence 

 external to the glacier, it was passing with quite sensible 

 velocity. In fact, the antrum of the Glacier des Bossons, 

 in the summer of 1895, offered an example on a large scale 

 of a cold-pressed tube, of which the material was ice, which 



