WOOD 



113 



are defects that may occur in the tree at the time it is 

 cut or if the log is allowed to lie for a long period after 

 cutting, and these defects may be developed to such a point 



Fig. 

 A — Spike knot 



115- 



Knots 

 B — Circular knot 



that they render tne log worthless for sawing. Faulty 

 sawing may cause the stock to be thicker on one edge than 

 on the other, or it may be across the grain. Defective logs 

 are usually cut into dimension lumber and timber and 

 used rough. 



Finishing lumber and No. 1 lumber of the different 

 grades must be reasonably free from the above-named 

 defects, as a large part of it requires additional sawing or 

 machine work to put it into final form for use. Material 

 requiring paint, oil finish, or a smooth surface on one or 

 more sides must have the saw marks and roughness taken 

 off by the planing mill. Such lumber is known under the 

 term surfaced. The manufacture of implements and the 

 construction of modern buildings require special shapes and 

 sizes that necessitate putting the sawed lumber through a 

 machine to give it the desired form, after which it is known 

 under a trade name. 



