Cavities in Rocks exposed to High Pressures. 68?> 



At the pressures filially Eound requisite to break down the 

 resistance of the rock, there was no reason why two spheres 

 eon hi not he dealt, with at the one time. In this case two 



Fig. 1. 



spheres, as described above, were each enclosed in a separate 

 lead container having the dimensions already given, and 

 these containers placed in the crushing mortar. The copper 

 flanges were applied, of: course, to one end only of each 

 cylinder. 



2 Y 2 



