EEPOBT OF THE FOEBSTEE.- 35 



TIMBER TESTS. 



Information on the mechanical and pliysical properties of wood 

 is in strong demand. The structural timber tests were put to im- 

 mediate use by the American Railway Engineering and Mainte- 

 nance of Way Association and the American Society for Testing 

 Materials in drawing up standard specifications of such timbers. 

 The work promoted interest in a more scientific use of wood, which 

 is synonymous with a more economical use. 



The tests were made at laboratories run in cooperation with Yale 

 University, Purdue University, the University of California, the 

 University of Oregouj and the University of Washington. To co- 

 ordinate closely the work of these different laboratories an office hav- 

 ing general supervision over all the work was established at Wash- 

 ington early in 1907. 



Work cojipleted during the year. — There were made during 

 the year 10,726 mechanical tests, of which 1,871 were in bending, 

 7,957 in compression, and 898 in shearing. 



These tests developed, among other facts, that white fir and Engel- 

 mann spruce have about the same strength as eastern spruce, while 

 lodgepole pine is almost as strong as loblolly pine ; that in small pieces 

 sound dead timber of these species has about 85 per cent of the 

 strength of live, and that these woods are suitable for many purposes 

 for which more valuable woods are now being used; that various 

 species of eucalypts compare favorably in strength with our strong- 

 est native woods, and will probably make suitable material for 

 vehicles and implements; that insulator pins of live oak and rock 

 elm have, respectively, 75 and 65 per cent of the strength of locust 

 pins ; that in railroad ties of white and red oak, loblolly pine, hardy 

 and common catalpa, and chestnut, with spikes of the common, chan- 

 neled, and screw types, the channeled spike has 12 per cent more 

 holding power than the common spike and the screw spike about 

 twice that of the common spike, while white oak has the greatest 

 holding power of the species tested; that western hemlock timber 

 has much structural merit, being a little stronger than loblolly pine ; 

 and that Norway pine is weaker than tamarack, and both are weaker 

 than Douglas fir, longleaf pine, loblolly pine, and western hemlock. 



Tests of loblolly pine bridge stringers secured, with the previous 

 work upon this species, sufficient data to form the basis of an au- 

 thoritative future report upon its mechanical and physical proper- 

 ties. Data were secured as to the effect of knots and other defects, 

 rate of growth, specific gravity, proportion of summerwood, and vari- 

 ous other qualities on the strength of large Douglas fir timbers. 

 Tests on vehicle woods covered spokes, axles, wagon and cultivator 

 poles, and buggy shafts, and developed that the discrimination made 

 by the trade against red hickory is not justified in so far as its 

 strength is concerned. Tests on wagon axles showed the relative 

 value of maple and hickory, and the benefits derived from various 

 forms of trussing. The results of these tests will enable vehicle 

 manufacturers to use material more economically and assist them to 

 find satisfactory substitutes for woods that are now hard to secure. 



Tests to determine the fiber-saturation point and moisture strength 

 relations for loblolly pine, Douglas fir. Eucalyptus globulus, western 



