oisture content but also its distribution
through the timber, the disks are cut up so as to obtain an
outside, a middle, and an inner portion, of approximately equal
areas. Thus in a section 10" x 12" the outer strip would be one
inch wide, and the second one a little more than an inch and a
quarter. Moisture determinations are made for each of the three
portions separately.

The procedure is as follows:

(1) Immediately after sawing, loose splinters are removed and
each section is weighed.

(2) The material is put into a drying oven at 100 deg. C. (212 deg. F.)
and dried until the variation in weight for a period of
twenty-four hours is less than 0.5 per cent.

(3) The disk is again carefully weighed.

(4) The loss in weight expressed in per cent of the dry weight
indicates the moisture content of the specimen from which the
specimen was cut.

MACHINE FOR STATIC TESTS

The standard screw machines used for metal tests are also used
for wood, but in the case of wood tests the readings must be
taken "on the fly," and the machine operated at a uniform speed
without interruption from beginning to end of the test. This is
on account of the time factor in the strength of wood. (See
SPEED OF TESTING MACHINE, below.)

The standard machines for static tests can be used for
transverse bending, compression, tension, shear, and cleavage. A
common form consists of three main parts, namely: (1) the
straining mechanism, (2) the weighing apparatus, and (3) the
machinery for communicating motion to the screws.

The straining mechanism consists of two parts, one of which is a
movable crosshead operated by four (sometimes two or three)
upright steel straining screws which pass through openings in
the platform and bear upward on the bed of the machine upon
which the weighing platform rests as a fulcrum. At the lower
ends of these screws are geared nuts all rotated simultaneously
by a system of gears which cause the movable crosshead to rise
and fall as desired.

The stationary part of the straining mechanism, which is used
only for tension and cleavage tests, consists of a steel cage
above the movable crosshead and rests directly upon the weighing
platform. The top of the cage contains a square hole into which
one end of the test specimen may be clamped, the crosshead
containing a similar clamp for the other end, in making tension
tests.

For testing long beams a special form of machine with an
extended platform is