of the work here outlined to provide:

(_a_) Reliable data for comparing the mechanical properties of
various species;

(_b_) Data for the establishment of correct strength functions
or working stresses;

(_c_) Data upon which may be based analyses of the influence on
the mechanical properties of such factors as:

Locality;

Distance of timber from the pith of the tree;

Height of timber in the tree;

Change from the green to the air-dried condition, etc.

The mechanical properties which will be considered and the
principal tests used to determine them are as follows:

Strength and stiffness--
Static bending;
Compression parallel to grain;
Compression perpendicular to grain;
Shear.

Toughness--
Impact bending;
Static bending;
Work to maximum load and total work.

Cleavability--
Cleavage test.

Hardness--
Modification of Janka ball test for surface hardness.

MATERIAL

_Selection and Number of Trees_

The material will be from trees selected in the forest by one
qualified to determine the species. From each locality, three to
five dominant trees of merchantable size and approximately
average age will be so chosen as to be representative of the
dominant trees of the species. Each species will eventually be
represented by trees from five to ten localities. These
localities will be so chosen as to be representative of the
commercial range of the species. Trees from one to three
localities will be used to represent each species until most of
the important species have been tested.

The 16-foot butt log will be taken from each tree selected and
the entire merchantable hole of one average tree for each
species.

_Field Notes and Shipping Instructions_

Field notes as outlined in Form--_a_ Shipment Description,
Manual of the Branch of Products, will be fully and carefully
made by the collector. The age of each tree selected will be
recorded and any other information likely to be of interest or
importance will also be made a part of these field notes. Each
log will have the bark left on. It will be plainly marked in
accordance with directions given under Detailed Instructions.
All material will be shipped to the laboratory immediately after
being cut. No trees will be cut until the collector is notified
that the laboratory is ready to receive the material.

DETAILED INSTRUCTIONS

_Part of Tree to be Tested_

(_a_) For determining the value of tree and locality and