SELLINGLUMBER 335 



which organization was succeeded by the Yellow Pine Manufact- 

 urers' Association and then by the Southern Pine Association. 

 These organizations were always in the lead in this work, but 

 during this time the standardization of manufacture and grading 

 was undertaken by the Atlantic Coast Association, which origin- 

 ated what are known as the Interstate Rules of 1905. All of these 

 rules were based on a permissible maximum number of defects 

 and disregarded entirely the strength and durability of the wood. 

 Hence, we have such grades as Standard, Merchantable and Prime 

 on the Atlantic Coast, and the old grades of No. 1 Common and 

 No. 2 Common, in the central portion of the Yellow Pine bearing 

 district. 



These rules do not provide for the necessities of architects 

 and engineers in all cases, inasmuch as they do not fix any old Rules 

 strength value, and it is principally strength and durability with NotSatis- 

 which structural experts are concerned. actory 



As a result of these unscientific grading rules it has been 

 difficult to procure a satisfactory material, having a dependable and 

 uniformly measureable strength. 



The term, "Commercial Long Leaf" is often used in specifi- 

 cations for structural material. The employment of such terms 

 as "Long Leaf" and "Short Leaf" in an effort to segregrate qual- 

 ity classes is not only ineffective, in view of the fact that there is 

 a very wide and over-lapping margin of quality in the several 

 Southern Pine species, but also leads to considerable confusion and "Long Leaf" 

 loss of money in cases under dispute, since it is practically impo?- "Short Leaf 

 sible to determine the species from a visual examination of manu- Confusing 

 factured timbers; the only absolute method for the determination 

 of the different species is by microscopical examination which in- 

 volves too much labor and expense for general use by lumbermen. 



Realizing the necessity for the determination of the strength 

 bearing qualities of the various types of timber the U. S. Forest 

 Service undertook a series of tests calculated to establish the 

 fact that the strength of Yellow Pine is dependent upon its specific 

 gravity and density, or rate of growth. The Forest Service pro- The Forest 

 ceeded upon the theory that any grading rules which it might Service Sought 

 recommend, based upon this premise, should be simple, while at w 

 the same time they should exclude all material that should not be 

 used in mill construction with the fiber stress recommended for 

 the grade, while not excluding more than a reasonable amount 



