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2.) This is a common form of failure where the beam has diagonal, spiral or other form of cross grain on its lower side.

Since the tensile strength of wood across the grain is only a small fraction of that with the grain it is easy to see why a cross-grained timber would fail in this manner.
(3)~Splintering tension,~ in which the failure consists of a considerable number of slight tension failures, producing a ragged or splintery break on the under surface of the beam.

(See Fig.

17, No.