TIMBER 297 



In sizes over 6 by 6, knots not to exceed 2 in. in diameter, varying accord- 

 ing to the size of the piece ; sap on corners not to exceed 3 in. on both face and 

 edge ; pitch seams not to exceed 8 in. in length. 



Defects in all cases to be considered in connection with the size of the 

 piece and its general quality. 



The cross-bending tests of 1 were made upon large specimens 

 ranging in size from 6 in. x 8 in. x 7 ft., to 8 in. x 16 in. x 16 ft. The 

 table shows that the modulus of rupture is less for the poorer grades 

 of timber than for the selects, showing the effect of knots and other 

 imperfections. The modulus of elasticity, indicating the stiffness, 

 is less for the poorer grades, except in the case of shipment B of 

 red fir. 



The same report also makes a comparison of the strength of large 

 sticks and small sticks, both in cross bending and in compression 

 parallel to the fiber. 



The table on page 296 gives average values obtained from this 

 report, and indicates that the strength of the small sticks is, in nearly 

 every case, greater than the strength of the large sticks. The modu- 

 lus of elasticity is less for the small sticks than for the large ones, 

 indicating a greater stiffness for the latter. 



