BUREAU OF FORESTRY. 201 



These tests were uot completed. The results have not j-et been entirely 

 formulated. 



A preliminary investigation, begun in May, 190-4. to determine the 

 best methods for seasoning beech, maple, and birch ties, from the 

 Adirondacks, so as to prevent excessive checking and to bring them 

 into a condition fit for treatment, is now under way. 



Timber Tests. 



During the past year the programme for a series of timber tests was 

 completed. The work thus far accomplished was largely of a prelimi- 

 nary character. Additional laboratories were located, further equip- 

 ment was purchased, and additional investigations were undertaken. 

 The programme has been submitted for criticism to the American 

 Society of Civil Engineers and the American Society for Testing 

 Materials, and has received their hearty indorsement. 



A large volume of data concerning the strength of structural timber 

 in actual market forms and sizes was obtained, which will be useful in 

 economizing the use of timber, perfecting specifications, and establish- 

 ing rules for inspection. The relative strength of red fir, western 

 hemlock, loblolly pine, and longleaf pine, with characteristic defects, 

 was in part determined. A study of the mechanical properties of red 

 gum wood was made, and its availability for carriage manufacture was 

 established. Studies of the relative strength of tie fastenings, in order 

 to determine the proper form for inferior timbei's, have also been 

 made. 



An impact testing machine was designed and built, and proper meth- 

 ods of test were developed to determine the brittleness of timber pre- 

 paratory to a study of the efl'ects of preservative processes on its 

 mechanical properties. The law governing the influence of moisture 

 on the strength of timber was developed with a completeness of detail 

 and scientific precision hitherto unknown. It remains to extend this 

 inquiry to the degree of moisture existing in large timbers, and to 

 ascertain if any increase in strength mav be counted on in the case of 

 large sticks as found partially dried on the market. A preliminary 

 examination has been made of the problem of determining the strength 

 of boxboard lumber of various species. 



The tests of red fir and western hemlock were made at the timbei'- 

 testing station of the University of California. The work at the 

 Yale Forest School station included a determination of the efl'ects of 

 moisture and resin on the mechanical properties of timber. This 

 work requires great care in detail. 



The tests of loblollj' and longleaf pine were made in cooperation 

 with the Bureau of Chemistry, United States Department of Agricul- 

 ture, at Washington. 



* The work at the Purdue University station included the study of 

 the mechanical properties of red gum. The relative strength of sap- 

 wood and heartwood, both clear and mill-run, the relative strength of 

 mature and immature timber, and the ability of red gum wood to 

 withstand the operations of kiln drying, steaming, and bending which 

 are necessary in the application of the wood to carriage stock, were 

 determined. Other subjects investigated at this station were the 

 pulling strength of the screw-spike as compared with the common 

 spike when driven into railroad ties, a method of test to determine 



