USE OF THE FOREST 



173 



hand, we can readily make one, for in Doyle's rule the 

 contents of a log sixteen feet long are equal to the square 

 of the diameter reduced by four. Thus, a log twenty-four 

 inches in diameter has (24 - 4) 2 = 20 x 20, or 400, feet B.M. 

 if it is sixteen feet long. If it is only twelve feet 

 long, the contents are 400 x f J = 300 feet B. 



The measurement is always made 

 at the smaller or top end, and if the 

 log is crooked, partly decayed, or 

 excessively knotty, an arbitrary deduc- 

 tion is made. Where valuable timber 

 is bought or sold these methods are 

 improved in various ways to obtain 

 more exact results. 



Tan Bark. In many of the oak 

 forests of the Allegheny region, and 

 in the hemlock woods of Wisconsin 

 and Michigan, many men are engaged 

 in peeling tan bark. 



This is done in summer, May to 

 July, while the bark readily lets go of FIG. 64. Scale Rules 

 the wood. In peeling bark the tree Only the lower end of each 

 is felled, and then girdled every four 

 feet clear up to the crown. Then these four-foot cylinders 

 of bark are cut lengthwise along two or more lines, and 

 the pieces peeled off with a special peeling iron. They 

 are then set up, rough side out, against the log to dry. 



