TIMBER 



295 



FLEXURE TESTS OF COMMERCIAL TIMBER 



The grades selects, merchantable, and seconds, referred to in the table, 

 ;t i- those from the Pacific Coast standard grading rules for Douglas 

 Fir for 1900. A copy of these rules is here given. 



Merchantable. This grade shall consist of sound, strong lumber, free from 

 s}iak->, large, loose, or rotten knots, and defects that materially impair its 

 jh : it >liall be well manufactured and suitable for good substantial 

 roiiMnn-tiunal purposes. 



Will allow occasional variations in sawing or occasional scant thicknesses, 

 >!! ml knots, pitch seams, and sap on corners, one third the width and one half 

 th- thickness. Defects in all cases to be considered in connection with the 

 size of the piece and its general quality. 



Seconds. This grade shall consist of lumber having defects which exclude 

 ii ^nulin^ as merchantable. 



HV.V nl f on- knots and defects which render it unfit for good substantial con- 

 st rurtidiial purposes, but suitable for an inferior class of work. 



Selects. Shall be sound, strong lumber, good grain, well sawn. 



U'ill allow, in sizes 6 by 6 and less, knots not to exceed 1 in. in diameter; 

 sap on corners one fourth the width and one half the thickness ; small pitch 

 seams when not exceeding 6 in. in length. 



