This is a perfectly legitimate procedure provided no drying is allowed from the sides of the specimen, and the moisture disk is cut from the region of failure.
_Calculating the results:_ The formulae used in calculating the results of tests on endwise compression are as follows: P (1) C = -- --- A P_{1} (2) c = -- ----- A P_{1} l (3) E = -- ------- A D P D (4) S = -- --- 2 V C = crushing strength, pounds per square inch.
c = fibre strength at elastic limit, pounds per square inch.
A = area of cross section, square inches.
l = distance between centres of collars, inches.
D = total shortening at elastic limit, inches.
V = volume of specimen, cubic inches.
Remainder of legend as in BENDING LARGE BEAMS, above.
COMPRESSION ACROSS THE GRAIN _Apparatus_: An ordinary static testing machine, a bearing plate, and a deflectometer are required.

(See Fig.

35.) [Illustration: FIG.

35 .-- Compression across the grain.

Note method of measuring the deformation by means of a deflectomoter.] _Preparing the material_: Two classes of specimens are used, namely, (1) sections of commercial sizes of ties, beams, and other timbers, and (2) small, clear specimens with the length several times the width.