416 APPLIED SCIENCE 



479. Effects of Seasoning on the Strength of Wood. 



Seasoning, as a rule, increases the strength of wood. The 

 increase in strength, however, gained by this lowering of the 

 moisture content is somewhat greater for small, clear pieces 

 than for timbers of structural size, because seasoning does 

 not, as a rule, cause any appreciable defects to appear in 

 the small pieces, while it often develops checks in large 

 timbers. 



Questions 



1. What are the principal defects in lumber? 



2. What is a knot? 



3. What causes shrinkage of wood? 



4. What causes warping? 



5. What causes wood to rot? 



6. The strength of wood depends upon certain factors. What 

 are they? 



7. Draw a sketch showing the structure of wood. 



8. Describe the different methods of cutting wood. 



