Woods and Their Properties 



43 



FIG. 



U. S. Forest Service 

 25. Chestnut wood photo- 



graphed through a microscope. Chest- 

 nut is a ring-porous wood; that is, 

 the large pores are collected in the 

 springwood. 



U. S. Forest Service 



FIG. 26. Wood of the black cherry 

 as seen under the microscope. It is 

 diffuse-porous; that is, the large 

 pores are scattered through both the 

 spring and summer wood. 



and in many other ways. Since the properties of a wood 

 depend in great part upon its structure, it is well to 

 understand how the different elements of which wood is 

 composed are arranged in some common woods of dif- 

 ferent kinds. 



Three classes of woods. In oak, elm, hickory, and 

 ash, large tracheae (page 12) are especially numerous 

 in the wood formed in spring, and the cut-off ends of 



