280 JOURNAL OF FORESTRY 



Structure with their resulting differences in strength properties. No 

 methods, therefore, are at hand for the appraiser to use in determining 

 within reasonable limits the percentage of dense structural timber in a 

 stand. It is possible that stump borings made upon sample areas or in 

 connection with the timber survey would work out satisfactorily, but 

 until the whole subject of growth in relation to density has been 

 worked out by the silviculturist, the stumpage appraiser will be at a 

 loss to know the best method of determining the quality of timber in a 

 stand. 



The relation of density to silviculture and forest administration goes 

 further. In forest administration, whether national, regional or strictly 

 local, a ready method of determining the density of the wood in stand- 

 ing timber would be a tremendous aid in adjusting lumber supply to 

 market needs. For example, if the market for structural timber were 

 overloaded, with prices depressed, the Service would possibly not de- 

 sire to place on the market large tracts of timber which ran high to 

 structural timber, whereas, if conditions were reversed, if the market 

 were in urgent need of structural material, those tracts containing large 

 amounts of timber of the required density could first be thrown on the 

 market with a minimum accumulation of so-called side lumber. In a 

 similar but smaller way, the lumberman could from a purely business 

 standpoint, more advantageously select his timber for cutting so as to 

 adjust his production to his market requirements. The full signifi- 

 cance of the application is best visualized by the situation with respect 

 to specific and exact requirements for w^ood for special uses such as 

 existed during the war and the requirements as we now comprehend 

 them, of a possible future war. 



Closely allied to density of wood structure as a factor of strength is 

 diagonal and spiral grain. By the former is meant wood in which the 

 fibres extend diagonally (usually indicated by the annual layers of 

 growth) across the piece on the radially cut surfaces, while in the 

 latter the fibres extend in an oblique direction circumferentially around 

 the tree. Logs are ordinarily sawn parallel to the axis of the tree, thus 

 cutting the fibres obliquely and producing diagonal grain of varying 

 degrees, depending upon the uniformity of the wood growth. It can 

 often be satisfactorily taken care of by methods of sawing or manu- 

 facture, such as the innovation during the war of sawing parallel to 

 the outside of the log instead of parallel to its axis, in order to get 

 more straight-grain material for aircraft construction. 



