LUMBER 



401 



the durability of the wood in service, (2) to prevent it from 

 shrinking and checking, (3) to increase its strength and stiff- 

 ness, and (4) to decrease its weight. The sooner wood is 

 seasoned after being cut, the less is it likely to be injured 





FIG. 191. Section of a Large Lumber Yard. Showing natural 

 method of drying lumber. 



by the insects which attack unseasoned wood and cause it 

 to decay rapidly. Wood that is to be treated with a preser- 

 vative needs, in nearly all cases, to be seasoned as much as 

 wood that is to be used in its natural state. 



The natural method of drying consists in stacking the 

 wood in horizontal piles and exposing it to the air Fig. (191). 

 Flat or horizontal piling may be done in two ways: (1) with 

 26 



