396 



AMERICAN FORESTRY 



to ascertain how these properties are 

 affected by different methods of drying 

 and handling. This section has in hand 

 at present a miscroscopic examination 

 of American woods for the purpose of 

 developing a key to their identifica- 

 tion based on the structure of the 

 wood; experiments to determine heat 

 conductivity and other heat constants 

 for the principal commercial timbers. 

 In the kiln drying of lumber and in the 

 treatment of woods with preservatives 

 it is of importance to know how much 

 heat is required, and how long it takes 

 to heat wood to a given temperature. 

 A third line of experiments is the study 

 of different methods of drying wood. 



The equipment of this section in- 

 cludes microscopes, microtomes, and 

 other apparatus required for micro- 

 scopic work, apparatus for taking micro- 

 phctographs, a cylinder designed for 

 the study of the different methods of 

 drying wood, and an experimental dry- 

 kiln, balancers, ovens, calorimeters, and 

 other miscellaneous equipment. 



TIMBER TESTS 



In the section of timber tests studies 

 are made of the strength, stiffness, 

 hardness, and other mechanical prop- 

 erties of commercial wood. There are 

 some very interesting machines for de- 

 termining these points. Tests are made 

 on woods that have been treated with 

 preservatives and other substances to 

 determine the effect of the preservative 

 treatment upon the mechanical prop- 

 erties of the natural wood. 



The lines of work to be taken up in 

 this section include tests of the dif- 

 ferent commercial woods to determine 

 their relative strength, toughness, 

 hardness, etc. This work is of par- 

 ticular value to wood users in finding- 

 substitutes for woods now becoming 

 scarce. It is the same type of work 

 that led to the discovery which has 

 already been referred to of the value 

 of red hickory. Tests will also be made 

 to determine the influence of knots, 

 checks, and other defects used in grad- 

 ing structural timbers upon "their 



strength and other mechanical prop- 

 erties. The results of these tests, of 

 course, will be of great value to archi- 

 tects, engineers, and lumbermen in 

 making specifications and grading rules 

 for structural timber. Tests will be 

 made to determine the strength of 

 wood under dead, impact, or repetitive 

 loading. Such tests will assist in de- 

 termining the working stress that may 

 be used upon timber structures. One 

 of the interesting pieces of apparatus 

 used in this laboratory is the machine 

 for making the dead-load test, and one 

 of the surprising results which the rec- 

 ord of this machine shows is that the 

 rapidity of loading does not affect the 

 elasticity of the wood. The mechanical 

 properties of wood that is impregnated 

 with creosote and other preservatives 

 \\ill also be determined in this section. 



The equipment of this laboratory in- 

 cl tries one 2OO,ooo-pound extension- 

 base Reihle testing machine, one 

 i5O,ooo-poimd extension-base Olsen 

 testing- machine, three 3O,ooo-pound 

 < Msen universal testing machines, one 

 6o,ooo-inch-pound Reihle torsion ma- 

 chine, one Dory abrasion machine, one 

 impact testing machine, deflectome- 

 ters, and other instruments used in 

 testing structural materials. Our il- 

 lustrations show some of this machin- 

 ery. The nature of some of the timber 

 tests is also shown in some of the ac- 

 companying illustrations. 



WOOD PRESERVATION 



This is an interesting and important 

 section. More and more it becomes 

 necessary, in the face of a diminish- 

 ing timber supply, to preserve in some 

 fashion poles, posts, ties, and all timbers 

 that are exposed to influences that will 

 cause them to deteriorate. Somehow 

 their life must be extended until sup- 

 plies can be regrown. Much progress 

 has been made in the work of wood 

 preservation, but a great deal remains 

 to be learned. This section is making a 

 broad study of the problems involved. 

 These deal with the preservatives them- 

 selves and their effects upon wood, and 

 with the methods of impregnating the 



