344 POPULAR LECTURES AND ADDRESSES. 



have time to look at it again we shall see the wire 

 thoroughly embedded in the ice. This practically 

 illustrates my brother's theory of the plasticity of 

 ice according to which one side of the wire presses 

 into the ico, and in pressing cools and melts it. 

 The ice relieved from pressure and the water 

 coming together around the wire give rise to freez- 

 ing above the wire. In general if pressure not 

 equal in all directions be applied to ice, we have 

 a solid which if it melts will relieve itself from 

 that stress. A solid so circumstanced relieves itself 

 from stress by inter-molecular melting ; and takes 

 up a form free from stress by re-freezing. 



In an investigation brought before the Royal 

 Society of London last May by Dr. Main, it was 

 stated that experiments made in the Engadine during 

 February, 1887, with the temperature many degrees 

 below freezing point, upon slabs of solid ice, showed 

 that these yielded regularly as any other viscous 

 body yields. Main's investigation gave perfectly 

 definite results, though differing considerably with 

 the temperature, lie found that a bar of ice can 

 be elongated. Take a bar of sealing wax ; hang a 



