VOLUME XXIx NUMBER 1 
THE 
BOwWKNAL OF GEOLOGY 
JANUARY FEBRUARY ro27 
THE MECHANICAL INTERPRETATION OF JOINTS 
WALTER H. BUCHER 
University of Cincinnati 
Je IE JEL 
OUTLINE 
Mour’s THEORY 
Mour’s THEORY APPLIED TO EXPERIMENTAL DATA 
THE ELLIPSOID OF STRAIN 
PLANES OF SHEARING PRODUCED BY IRROTATIONAL AND ROTATIONAL STRAINS 
PLANES OF SHEARING IN SHALES 
HorizoNTAL COMPRESSIVE STRAINS IN Camas 
Low-ANGLE FAULTING 
I. MOHR’S THEORY OF RUPTURE! 
BY LOUIS BRAND 
Let P denote a point of a body at which the state of stress is 
to be investigated. For this purpose imagine a sphere of infinitesi- 
mal radius described about P as center (Fig. 10); then the totality 
of the stresses at all the surface elements of the sphere constitute 
the state of stress at the point P. A surface element of the sphere 
may be specified by means of the vector radius to the element. 
The surface v thus means an infinitely small plane surface tangent 
to the sphere at the end of ry. In the following, the stresses shown 
t This account of Mohr’s theory of rupture was written at the writer’s request by 
Professor Louis Brand, of the University of Cincinnati, to whom he wishes herewith 
to express his sincere thanks. ; 
