face in terms of rectangular specification of stress-Stress-
quadric-Principal planes and axes of a stress-Varieties
of stress-quadric-Composition of stresses-Laws of strain
and stress compared-Rectangular elements of strains and
stresses-Work done by a stress within a varying solid-
Work done on the surface of a varying solid-Strain-
components in terms of displacement-Work done through
interior; agrees with work done on surface-Differential
equation of work done by a stress- Physical application—
Perfectly elastic body defined, in abstract dynamics--Its
conditional fulfilment in nature-Potential energy of an
elastic solid held strained-Stress-components expressed
in terms of strain-Strain-components expressed in terms
of stress-Average stress through any changing strain
Homogeneousness defined-Molecular hypothesis assumes a
very fine grained texture in crystals, but no ultimate
homogeneousness-Scales of average homogeneousness—
Isotropic and eolotropic substances defined-Isotropy and
eolotropy of different sets of properties-Practical limita-
tion of isotropy, and homogeneousness of eolotropy, to the
average in the aggregate of molecules-Conditions fulfilled
in elastic isotropy-Measures of resistance to compression
and resistance to distortion-Bulk-modulus or modulus of
compression-Compressibility-Rigidity, or elasticity of
-Ratio of lateral contraction to
Young's modulus defined-Same as longitudinal rigidity-
Weight-modulus and length of modulus-Velocity of
transmission of a simple longitudinal stress through a rod
-Specific Young's modulus of an isotropic body in terms
of the absolute unit; or of the force of gravity on the unit
of mass in any particular locality-Metrical denomina-
tions of moduluses of elasticity in general
Practical rules for velocities of waves; distortional without
change of bulk; compressional, in an elastic solid; com-
pressional in liquid; compressional in gas; gravitational
in liquid; transversal vibration of stretched cord-Digres-
sion on Resilience, from Art. Elasticity, Encyc. Brit.
VOL. II.