MEASUREMENT OF LOGS AND OTHER FOREST PRODUCTS 109 



United States and there is a wide variance among them in the 

 contents shown for logs of a given size. Some rules are based on 

 mathematical formulas ; some on diagrams which show the num- 

 ber of boards that may be cut with an assumed allowance for 

 slabs and saw-kerf; others on actual tally at the tail of the 

 mill; while certain ones are a combination of two of the above 

 methods. 



Many of the present rules were prepared years ago when 

 logging and milling methods were not as efficient and intensive 

 as they are to-day. There are only two rules, namely, the 

 International and the Champlain, which give results closely 

 approximating the sawing contents of logs and these are in 

 limited use. The discrepancy in any rule, however, is not of 

 great moment if its deficiencies are fully understood by all 

 the parties interested in the measurement of a certain lot of 

 logs. 



International Rule} — This rule is designed for the measure- 

 ment of logs which are to be cut by a band saw. 



The rule is based on the formula: 



Bf = 0.22 D' - 0.71 D, 



in which Bf represents the yield in board feet, D the top diam- 

 eter inside the bark, 0.22 D^ the contents in board feet of a 4-foot 

 section less a deduction for saw-kerf and shrinkage in seasoning 

 and 0.71 Z) the waste incident to square edging and to normal 

 crook. 



The formula is based on the following principles : 



(i) The saw-kerf is | inch. 



(2) The loss from shrinkage and unevenness in sawing is ^^g 

 inch. 



(3) The minimum board considered is not less than 3 inches 

 wide and contains at least two board feet. 



(4) The taper of logs is | inch for each 4 feet of length. 



(5) The average crook in first-class logs is 1.5 inches and 

 does not exceed 4 inches in a 12-foot log. 



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



