e 
5? THE WOODSMAN S HANDBOOK. 
formula: Multiply the square of the diameter of the small end of 
the log inside the bark by the length of the log, and divide the 
product by 30. The result is the contents in board feet. 
The Chapin Rule. 
The Chapin Rule is based on measurements of logs actually 
sawed into lumber. It is claimed that it gives the greatest amount 
of lumber which can be manufactured from straight, smooth logs. 
It is a comparatively new rule and has not yet come into very 
general use. 
The Northwestern Rule. 
This rule is used in Michigan, Illinois, New York, Massachu- 
setts, and Pennsylvania. It is based upon the tallies of logs 
sawed at the mill. 
The Derby Rule. 
This rule, which is also known as the Holden and Robinson 
Rule, is used in Massachusetts. It is based primarily upon dia- 
grams. The table thussecured was adjusted by tallies kept at the 
mill. 
The Partridge Rule. 
This is also known as the Murdoch and Fairbank Rule. It is 
used in Massachusetts. It is based upon diagrams and shows the 
number of feet of seven-eighths inch boards that can be sawed from 
logs of different sizes. It is often incorrectly used for inch boards. 
The Preston Rule. 
The Preston Rule is based upon the principle that one-fifth of 
the contents of a log should be deducted for saw kerf. The waste 
for slabs is calculated by deducting 1} inches for small logs and 
13 inches for large logs. The results are given in board feet and 
inches. This is a comparatively new rule. 
The Parsons Rule. 
This rule was probably made from diagrams. It is used in a 
few places in Maine. 

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