FOREST SERVICE. 231 



character has made itself felt with increasing force. A method was 

 developed which it is believed will be widely adopted for the anal- 

 ysis of coal-tar creosote, and a report upon it was prepared. 



TIMBER TESTS. 



The work in timber testing during the past year has progressed 

 toward a closer relation to other work in forestry, especially toward 

 serving the interests of conservative forest management by showing 

 the structural value of rapid-growth timber. Progress has also been 

 made in promoting the use of preservatives by studying their effect on 

 the strength of timbers and in studying the means by which preserved 

 railroad ties can be protected against the abrasive action of traffic. 

 Other useful work has been done in determining the mechanical 

 properties of proposed substitutes for timbers like white oak and 

 hickory, supplies of which for vehicle construction are rapidly dis- 

 appearing; in supplying data which will enable more satisfactory 

 and more accurate rules to be drawn up for the grading of structural 

 timber ; in supplying information on the technical properties of un- 

 familiar woods ; and in placing on a scientific basis the technique of 

 the methods of testing timber. 



The Forest Service now has a well-organized system of laboratories 

 and a trained staff of testing engineers. As yet, however, only a be- 

 ginning has been made on a few timbers, such as longleaf and loblolly 

 pine and red fir, but the greater part of the problem has not been 

 touched. 



The work of the year may be summed up as follows : 



At the Yale laboratory a bulletin entitled " The Effect of Moisture 

 on the Strength and Stiffness of Wood " has been prepared, based 

 upon a long series of tests. The study will serve to establish correct 

 methods of thinking on many fundamental matters in wood tech- 

 nology. 



The tests on red gum collected from Missouri and from Alabama 

 were, with the exception of certain tests on air-dried material, com- 

 pleted, and the results were published. 



At the laboratory at Berkeley, Cal., preliminary tests of the 

 mechanical properties of red fir collected from Washington,' Oregon, 

 and from the San Francisco market, and tests of western hemlock 

 collected from Washington and Oregon were completed. The tests 

 of western hemlock have given this timber the right to appear in the 

 market on its merits. 



The laboratory at Washington, D. C, completed a preliminary 

 study of the mechanical properties of loblolly pine and longleaf pine. 

 Already the results have aided manufacturers in the introduction of 

 these woods in foreign markets. With the tests on red fir they have 

 been of direct service to the Isthmian Canal Commission. They are 

 now being continued at Charleston, S. C. 



These various tests produced not only figures on large sticks for 

 structural purposes useful both to engineers and to lumbermen, but 

 also data which will result in the formulation of rules for determin- 

 ing the effect of various kinds of knots, and other defects, and of the 

 various rates of growth on the strength of timber. 



A preliminary publication, entitled " Progress Report on the 

 StreHgth of Structural Timbers," served a useful purpto'se. Variotis 



