ICE AND GLACIERS. 



125 



cylinder in its original condition; Fig. 24 represents its ap- 

 pearance after the action of the press. 



A still stronger proof of the pliability of ice is afforded 

 when one of our cylinders is forced through a narrow aperture.. 

 With this view I place a base on the previously described mould, 

 which has a conical perforation, FlG> 25 



the external aperture of which 

 is only two thirds the diameter 

 of the cylindrical aperture of 

 the form. Fig. 25 gives a sec- 

 tion of the whole. If now I 

 insert into this one of the com- 

 pressed cylinders of ice, and force 

 down the plug a, the ice is forced 

 through the narrow aperture in 

 the base. It at first emerges as 

 a solid cylinder of the same dia- 

 meter as the aperture; but as 

 the ice follows more rapidly in 

 the centre than at the edges, the free terminal surface of the 

 cylinder becomes curved, the end thickens, so that it could not 

 be brought back through the aperture, and it ultimately splits 

 off. Fig. 26 exhibits a series of shapes which have resulted in 

 this manner. 1 



FIG. 26. 



Here also the cracks in the emerging cylinder of ice exhibit 

 a surprising similarity with the longitudinal rifts which divide 



1 In this experiment the lower temperature of the compressed ice sometimes 

 extended so far through the iron form, that the water in the slit between the 

 base plate and the cylinder froze and formed a thin sheet of ice, although the 

 pieces of ice as well as the iron mould had previously laid in ice-water, and could, 

 not be colder than 0. 



