ICE AND GLACIERS. 139 



every crevice of the mould, and then that this powdered 

 ice, like snow, was again combined by freezing. This sug- 

 gests itself the more readily, since while the press is being 

 worked a continual creaking and cracking is heard in the 

 interior of the mould. Yet the mere aspect of the cylin- 

 ders pressed from blocks of ice shows us that it has not 

 been formed in this manner ; for they are generally clearer 

 than the ice which is produced from snow, and the indi- 

 vidual larger pieces of ice which have been used to pro- 

 duce them are recognised, though they are somewhat 

 changed and flattened. This is most beautiful when 

 clear pieces of ice are laid in the form and the rest of 

 the space stuffed full of snow. The cylinder is then seen 

 to consist of alternate layers of clear and opaque ice, the 

 former arising from the pieces of ice, and the latter from 

 the snow ; but here also the pieces of ice seem pressed 

 into flat discs. 



These observations teach, then, that ice need not be 

 completely smashed to fit into the prescribed mould, but 

 that it may give way without losing its coherence. This 

 can be still more completely proved, and we can acquire a 

 still better insight into the cause of the pliability of ice, 

 if we press the ice between two plane wooden boards, 

 instead of in the mould, into which we cannot see. 



I place first an irregular cylindrical piece of natural 

 ice, taken from the frozen surface of the river, with its 

 two plane terminal surfaces between the plates of the 

 press. If I begin to work, the block is broken by 

 pressure ; every crack which forms extends through 

 the entire mass of the block ; this splits into a heap of 

 larger fragments, which again crack and are broken the 

 more the press is worked. If the pressure is relaxed, all 

 these fragments are, indeed, reunited by freezing, but 

 the aspect of the whole indicates that the shape of the 

 block has resulted less from pliability than from fracture, 



