XCB AND GLACIERS ttf 



great terminal cascade of the Glacier des Bois. The ice 

 splits there into thousands of banks and cliffs, which then 

 recombme towards the bottom of the steeper slope and form 

 a coherent mass. 



This also we may imitate in our ice-mould. Instead of 

 the snow I take irregular pieces of ice, press them together; 

 add new pieces of ice, press them again, and so on, until 

 the mould is full. When the mass is taken out it forms a 

 compact coherent cylinder of tolerably clear ice, which has 

 a perfectly sharp edge, and is an accurate copy of the 

 mould. 



This experiment, which was first made by Tyndall, shows 

 that a block of ice may be pressed into any mould just like 

 a piece of wax. It might, perhaps, be thought that such a 

 block had, by the pressure in the interior, been first reduced 

 to powder so fine that it readily penetrated every crevice of 

 the mould, and then that this powdered ice, like snow, was 

 again combined by freezing. This suggests 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 cylinders 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 individual larger pieces of ice which 

 have been used to produce 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 com- 

 pletely 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, 



