140 



ICE AND GLACIERS. 



and that the individual fragments have completely altered 

 their mutual positions. 



The case is quite different when one of the cylinders 

 which we have formed from snow or ice is placed between 

 tho plates of the press. As the press is worked the creaking 

 and cracking is heard, but it does not break ; it gradually 

 changes its shape, becomes lower and at the same time 

 thicker ; and only when it has been changed into a tole- 

 rably flat circular disc does it begin to give way at the 

 edges and form cracks, like crevasses on a small scale. 

 Fig. 23 shows the height and diameter of such a cylinder 

 in its original condition ; Fig. 24 represents its appearance 

 after the action of the press. 



FIG. 24. 

 b 



A still stronger proof of the pliability of ice is afforded 

 when one of our cylinders is forced through a narrow aper- 

 ture. With this view I place a base on the previously 

 described mould, which has a conical perforation, the 

 external aperture of which is only two-thirds the dia- 

 meter of the cylindrical aperture of the form. Fig. 25 

 gives a section of the whole. If now I insert into this 

 one of the compressed cylinders of ice, and force down the 

 plug a, the ice is forced through the narrow aperture in 



