{ C = -- - } { A } [Illustration: FIG.

7 .-- Endwise compression of a short column.] It has been demonstrated[4] that the ultimate strength in compression parallel to the grain is very nearly the same as the extreme fibre stress at the elastic limit in bending.

(See Table V.) In other words, the transverse strength of beams at elastic limit is practically equal to the compressive strength of the same material in short columns.

It is accordingly possible to calculate the approximate breaking strength of beams from the compressive strength of short columns except when the wood is brittle.

Since tests on endwise compression are simpler, easier to make, and less expensive than transverse bending tests, the importance of this relation is obvious, though it does not do away with the necessity of making beam tests.
[Footnote 4: See Circular No.