38 .-- Two forms of shear test specimens.] In designing a shearing specimen it is necessary to take into consideration the proportions of the area of shear, since, if the length of the portion to be sheared off is too great in the direction of the shearing face, failure would occur by compression before the piece would shear.

Inasmuch as the endwise compressive strength is sometimes not more than five times the shearing strength, the shearing surface should be less than five times the surface to which the load is applied.

This condition is fulfilled in the specimens illustrated.
Shearing specimens are frequently cut from beams after testing.
In this case the specific gravity (dry), proportion of late wood, and rate of growth are assumed to be the same as already recorded for the beams.

In specimens not so taken, these quantities are determined in the usual way.

The sheared-off portion is used for a moisture section.
_Adjusting specimen in machine_: The test specimen is placed in the shearing apparatus with the tenon or lip under the sliding plate, which is centred under the movable head of the machine.
(See Fig.