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annual statement of the amount of lumber and other forest products - 
used, statistics are gathered and published in cooperation with the 
Bureau of the Census and the National Lumber Manufacturers’ Asso- 
ciation. The grading specifications under which lumber is manufac- 
tured by the various associations have been published. Some studies 
of special uses for woods have taken form in published reports upon 
cooperage woods, vehicle and implement woods, box woods, and 
methods of kiln-drying hardwoods. 
The timber tests are designed to secure a better knowledge of the 
comparative strength of timbers under various conditions, to add to 
the list of commercial species suitable for construction purposes, and 
to promote economy in the manufacture and use of timbers. The 
structural value of rapidly grown timber, and the effect of preserva- 
tives on the strength of timber, are examples of the subjects studied. 
Other studies aim at the collection of data for drawing up more accu- 
rate and satisfactory rules for the grading of structural timbers, the 
supplying of information on the properties of unfamiliar woods, and 
> the placing of the technique of timber testing on a scientific basis. 
The Forest Service conducts a series of laboratory experiments, 
under a trained staff of testing engineers, in cooperation with Yale and 
Purdue universities and the universities of the States of California, 
Washington, and Oregon. A bulletin has been printed on the effect 
of moisture on the strength and stiffness of wood. Preliminary tests 
to determine the mechanical properties of Douglas fir, loblolly, long- 
leaf, and Norway pines, western hemlock, and tamarack have been made. 
OFFICE OF WOOD PRESERVATION. 
In the office of wood preservation experiments are carried on to 
determine economical means of handling and treating wood to insure 
its greatest service. Practically all work is done in cooperation with 
persons or companies directly interested in the results. In coopera- 
tion with railroad companies improved methods have been found of 
treating with preservatives cross-ties of Douglas fir, lodgepole pine, 
western yellow pine, red oak, loblolly pine, hemlock, tamarack, 
western larch, and western hemlock. Test tracks have been laid con- 
taining untreated ties and ties subjected to different methods of treat- 
ment, in order to study their relative values under actual conditions 
of exposure. Different forms of metal and wooden tie plates have 
been employed with both screw and common spikes, in order to 
determine the most efficient rail fastening for softwood ties. Wooden 
tie plates have been used with both treated and untreated ties. 
Cooperative studies with telephone and telegraph companies have 
led to the adoption of open-tank methods of treatment for certain 
classes of material. Test lines have been established in which green, 
seasoned, and treated poles are placed successively to determine the 
[Cir. 36] 
