fh. Mallet-—Temperature attainable by Rock-crushing. 267 
smaller ones; much stress, however, cannot be laid upon this, 
as we cannot assume with any certainty what are the precise 
forced together, and the distribution of the crushing-pressure 
may be indefinitely varied. 
In the author's experiments the cubes crushed by pressure on 
two opposite faces were free upon the other four; it cannot be 
doubted that, had only two opposite faces been free and the 
pressure applied simultaneously upon the four other faces, two 
if none of the faces were free, and all those except the two 
opposite faces to which the crushing pressure is supposed applied, 
had the motion outwards of any of their particles opposed by 
o 
could calculate how much its temperature would be exalted 
by the work of the assigned deformation. 
amples, however, are not wanting which prove that a very 
large exaltation of temperature can thus be produced— » for 
example, in the old-fashioned method by which blacksmiths 
were accustomed to light their fires. A thin square rod of ver 
