108, U.S.Forest Service, p.

36.] WEIGHT, DENSITY, AND SPECIFIC GRAVITY From data obtained from a large number of tests on the strength of different woods it appears that, other things being equal, the crushing strength parallel to the grain, fibre stress at elastic limit in bending, and shearing strength along the grain of wood vary in direct proportion to the weight of dry wood per unit of volume when green.

Other strength values follow different laws.

The hardness varies in a slightly greater ratio than the square of the density.

The work to the breaking point increases even more rapidly than the cube of density.