no LOGGING 



The rule may be applied where saws are used which cut a kerf 

 greater or less than |-inch by adding or subtracting the per- 

 centages given in the following table: 



For j^-inch kerf add i . 3 per cent. 



For y\-inch kerf subtract 5 . o per cent. 

 For |-inch kerf subtract 9 . 5 per cent. 

 For j\-inch kerf subtract 13.6 per cent. 

 For f-inch kerf subtract 17.4 per cent. 

 For iV'nch kerf subtract 20.8 per cent. 



A test of this rule in a white pine mill in Canada showed an 

 overrun of 0.4 of one per cent on 403 logs which ranged in diam- 

 eter from 6 inches to 33 inches. 



Scribner Rule} — This rule, which is the oldest now in use, was 

 constructed from diagrams showing the number and size of 

 boards that could be sawed from logs of specified diameters after 

 allowing for waste. The contents of these boards were then calcu- 

 lated for different lengths and the table built up from the results. 



The common form of the rule now in use is called the Scribner 

 Decimal "C" rule. This differs from the original in that the 

 units are dropped and the values rounded to the nearest ten. 

 Thus ninety-seven board feet would be written ten, and ninety- 

 four board feet, nine. The original rule did not give values 

 below 12 inches but the table has been extended and now in- 

 cludes diameters from 6 to 120 inches. 



There are in use among lumbermen three different extensions 

 of the rule below 12 inches, known as the Scribner Decimal "A," 

 Scribner Decimal "B" and Scribner Decimal "C." 



The Scribner Decimal "C" rule has been adopted as the 

 standard for use in the National Forests and is the legal rule in 

 Minnesota, Idaho, Wisconsin and West Virginia. 



It gives fair results for small logs cut by a circular saw but 

 is too low for logs over 28 inches in diameter. In sound logs 

 the mill scale overruns the Scribner Decimal ''C" rule by from 

 10 to 20 per cent. 



Doyle Rule.^ — This rule is used in many sections of the 

 country and, except in Texas, it is the common rule in the pine 



^ A copy of this rule is given in the .Appendix. 



