2.) The latter is the condition more commonly met with in practice, as, for example, where a post rests on a horizontal sill, or a rail rests on a cross-tie.

The former condition, however, gives the true resistance of the grain to simple crushing.
[Illustration: FIG.

2 .-- Compression across the grain.] The first effect of compression across the grain is to compact the fibres, the load gradually but irregularly increasing as the density of the material is increased.

If the specimen lies on a flat surface and the load is applied to only a portion of the upper area, the bearing plate indents the wood, crushing the upper fibres without affecting the lower part.

(See Fig.