38: Instructions to engineers of timber
tests, 1906, p. 24.]

The form used by the Department of Forestry of New South
Wales[63] is as shown in Fig. 47. The specimen has a total
length of 41 inches and is circular in cross section. On each
end is a head 4 inches in diameter and 7 inches long. Below each
head is a shoulder 8.5 inches long, which tapers from a diameter
of 2.75 inches to 1.25 inches. In the middle is a cylindrical
portion 1.25 inches in diameter and 10 inches long.

[Illustration: FIG. 47.--Design of tension test specimen used in
New South Wales.]

[Footnote 63: Warren, W.H.: The strength, elasticity, and other
properties of New South Wales hardwood timbers, 1911, pp.
58-62.]

In making the test the specimen is fitted in the machine, and an
extensometer attached to the middle portion and arranged to
record the extension between the gauge points 8 inches apart.
The area of the cross section then is 1.226 square inches, and
the tensile strength is equal to the total breaking load applied
divided by this area.

TENSION TEST AT RIGHT ANGLES TO THE GRAIN

A static testing machine and a special testing device (see Fig.
48) are required. The latter consists essentially of two double
hooks or clamps, one of which is suspended from the centre of
the top of the cage, the other extended above the movable head.
The specimens are 2" X 2" X 2.5". At each end a one-inch hole is
bored with its centre equidistant from the two sides and 0.25
inch from the ends. This makes the cross section to be tested 1"
X 2".

[Illustration: FIG. 48.--Design of tool and specimen for testing
tension at right angles to the grain.]

The free ends of the clamps are fitted into the notches in the
ends of the specimen. The movable head of the machine is then
made to descend at the rate of 0.25 inch per minute, pulling the
specimen in two at right angles to the grain. The maximum load
only is taken and the result expressed in pounds per inch of
width. A piece one-half inch thick is split off parallel to the
failure and used for moisture determination.

TORSION TEST[64]

[Footnote 64: Wood is so seldom subjected to a pure stress of
this kind that the torsion test is usually omitted.]

_Apparatus_: The torsion test is made in a Riehle-Miller
torsional testing machine or its equivalent. (See Fig. 49.)

[Illustration: FIG. 49.--Making a torsion test on hickory.]

_Preparation of material_: The test pieces are cylindr