134 THE SCHOOL BOOK OP FORESTRY 



On arrival at the sawmill, the logs are re- 

 duced to lumber. Many different kinds of saws 

 are used in this work. One of the most efficient 

 is the circular saw which performs rapid work. 

 It is so wide in bite, however, that it wastes much 

 wood in sawdust. For example, in cutting four 

 boards of one-inch lumber, an ordinary circular 

 saw wastes enough material to make a fifth 

 board, because it cuts an opening that is one- 

 quarter of an inch in width. Band saws, al- 

 though they do not work at such high speed, are 

 replacing circular saws in many mills because 

 they are less wasteful of lumber. Although saw- 

 mills try to prevent waste of wood by converting 

 slabs and short pieces into laths and shingles, 

 large amounts of refuse, such as sawdust, slabs 

 and edgings, are burned each season. As a rule, 

 only about one-third of the tree is finally used 

 for construction purposes, the balance being 

 wasted in one way or another. 



