34 R. T. CHAMBERLIN AND W. Z. MILLER 
near the pressure block first yielded somewhat by plastic deforma- 
tion. Then, as a result of the shearing stresses, it started to break 
along a very low angle of fracture near the bottom of the block 
(Fig. 16, break A). The experiment was stopped at this point 
and the block removed for study. After a rest of a few days the 
deformed block was again placed in the crushing machine and 
Fic. 15.—Deformation of specially shaped paraffine block under non-rotational 
strain. Pressure applied uniformly upon right-hand face. Fracture averages 42°. 
pressure applied as before. But instead of further splitting along the 
old line of breakage near the bottom of the block, an entirely new 
break occurred at a much higher level (Fig. 16, break B). This 
new fracture extended completely across the block. Though irregu- 
lar in detail, its general direction was very close to horizontal. To 
verify these results, a new block of paraffine was cast in the same 
mold and pressure was again applied in the same way. The result 
again was breakage along a nearly horizontal shearing plane (Fig. 16, 
break C). In breaking out at the surface, however, the fault plane, 
