plane midway between the end nails. All three
nails should be in place before the beam is put into the
machine. The indicator is adjustable by means of a thumb-screw
at the base and is set at zero before the load is applied.
Deflections are read to the nearest 0.001 inch. For rate of
application of load see SPEED OF TESTING MACHINE, above. The
speed should be uniform from start to finish without stopping.
Readings must be made "on the fly."

_Log of the test_: The log sheets used for small beams (see Fig.
32) are the same as for large sizes and the procedure is
practically identical. The stress-strain diagram is continued to
or beyond the maximum load, and in a portion of the tests should
be continued to six-inch deflection or until the specimen fails
to support a load of 200 pounds. Deflection readings for equal
increments of load are taken until well beyond the elastic
limit, after which the scale beam is kept balanced and the load
read for each 0.1 inch deflection. The load and deflection at
first failure, the maximum load, and any points of sudden change
should be shown on the diagram, even though they do not occur at
one of the regular points. A brief description of the failure
and the nature of any defects is entered on the log sheet.

[Illustration: FIG. 32.--Sample log sheet, giving full details
of a transverse bending test on a small pine beam.]

_Calculating the results_: The formulae used in calculating the
results of tests on small rectangular simple beams are as
follows:

0.75 P
(1) J = --------
b h

1.5 P_{1} l
(2) r = -------------
b h^{2}

1.5 P l
(3) R = ---------
b h^{2}

P_{1} l^{3}
(4) E = -------------
4 D b h^{3}

P_{1} D
(5) S = ---------
2 V

The same legend is used as in BENDING LARGE BEAMS. The weight of
the beam itself is disregarded.

ENDWISE COMPRESSION

_Apparatus_: An ordinary static testing machine and a
compressometer are required. (See Fig. 33.)

[Illustration: FIG. 33.--Endwise compression test, showing
method of measuring the deformation by means of a
compressometer.]

_Preparing the material_: Two classes of specimens are commonly
used, namely, (1) posts 24 inches in length, and (2) small clear
blocks approximately 2" X 2" X 8". The specimens are surfaced on
all four sides and both e