338 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



They are based on the factors affecting the strength of timbers, as 

 determined by exhaustive tests, and are the only grades in existence 

 to which accurate working stresses can be applied. Structural tim- 

 bers have always been selected on the reputation of a species for 

 strength, widely different working stresses being given to the same 

 species in various building codes, usually without an}^ limitation as 

 to grade or quality. The result was sometimes dangerous — more 

 often wasteful — construction. In most cases the new working 

 stresses permit the use of smaller timbers, or fewer timbers, and so 

 make possible the saving of much material. 



In the latter part of 1922 the laboratory initiated studies of the 

 grading of hardwood lumber and softwood factory lumber. When 

 these are completed the four principal phases of lumber standardi- 

 zation will have been covered. Producers, distributers, and con- 

 sumers of lumber can well afford to depart from past practices to 

 the extent necessary to adopt this constructive and urgently needed 

 improvement in the lumber trade. 



Two years ago, with the general support of wood producing and 

 consuming interests, the laboratory set out to ascertain the dimension 

 stock requirements of all secondary wood-using industries to de- 

 termine the most economical method of converting the log directly 

 into the sizes required by these industries, to save waste through 

 more extensive manufacture of small, clear pieces, should that prove 

 possible, and to standardize and stabilize small dimension require- 

 ments. A year was devoted to determining the requirements of the 

 chair industry, embracing 165 factories in all parts of the country. 

 Some of the findings were: (1) The chair industry now uses about 

 16 per cent of its total wood requirements in the form of small di- 

 mension stock, but might use 78 per cent; (2) producing small 

 dimension stock from lumber at the chair factory requires an aver- 

 age of 50 per cent more raw material than is used, and the final 

 dimension cuttings cost one and one-half or two times the market 

 price of the lumber delivered at the factory; and (3) one-third of 

 the freight bill is on material wasted at the factory in the cutting-up 

 process. 



Subsequent studies of the dimension-stock requirements of the 

 wood-turning, automobile, and general furniture industries, though 

 not yet completed, point to the same general conclusions. Many 

 small sizes of lumber will be standard for several industries. A 

 program of small-dimension stock production, marketing, and use 

 in all industries is practicable and logical, and will constitute an 

 important step in the solution of the wood-waste problems of the 

 timberland owner, lumber manufacturer, and fabricator of wood. 

 It should be profitable to all the interests concerned, and particu- 

 larly should extend the life of our diminishing hardwood supply. 



In kiln drying, a series of experimental runs conducted last fall 

 in the Northwest disclosed how to dry Douglas fir common lumber. 

 A type of kiln that gives promise of performing this difficult dry- 

 ing is a new internal-fan, rapid-circulation kiln developed at the 

 laboratory. Through the cooperation of the West Coast Lum- 

 bermen's Association, a commercial kiln located in the Douglas fir 

 region was turned over to the Forest Service representatives, who 

 remodeled it and conducted demonstration runs for three months. 

 At the end of this time they had worked out a practical method of 



