THE MASSACHUSETTS LOG RULE 79 



out based directly on mill tallies. Unfortunately, most of the rules so 

 obtained are not standardized for lumber of a given width, as 1-inch 

 boards, but include the mill run, with varying per cents of thicker plank. 

 This requires a statement as to the basis of the rule. Even when based 

 on arbitrary per cents of 1-inch and thicker lumber such a rule may be 

 superior, for local use, to one of the older commercial rules. 



A mill tally, upon which a local log rule can be based, will also serve 

 two other purposes if rightly conducted, namely, a check on the amount 

 of over-run to be obtained from logs of different sizes if scaled by an 

 existing log rule (Doyle rule, § 65), and an analysis of the product of 

 the log by grades of lumber, leading to the construction of graded log 

 rules. 



For the single purpose of constructing a log rule for sound logs with 

 normal crook (§ 52) but two operations are required. Each log is meas- 

 ured, preferably at both the small end, inside bark, and the middle 

 diameter outside bark, and its length recorded. The contents of each 

 board sawed from the log is then tallied, and the total found, from which, 

 by averaging for logs of the same dimensions, and the use of graphic 

 plotting (§ 138) the log rule may be obtained. 



When mill-scale studies are made to check a given log rule, and to determine 

 contents of logs by grades, from which a graded log rule is constructed (§ 87), the 

 work is planned as follows: Each log is given a number, and is scaled as it enters 

 the mill. A second man stationed at the edger places this number on the first and 

 last board sawed from the log. A lumber grader at the grading table indicates the 

 grade of each board, while a fourth man tallies the board-foot contents of the piece 

 on a ruled blank which contains columns for each standard grade. As the scaler 

 and grader are usually employees of the mill the work requires two extra men in 

 the mill. 



The study is usually extended to include defective logs, which are kept separate 

 in the final averages, since the original scale of such logs is a matter of judgment 

 subject to wide errors. (Appendix A, § 361.) 



By a proper system of numbering the logs in the woods, a mill scale study may 

 be applied to determine the graded contents of entire trees for the construction of 

 graded volume tables (§ 165). 



Reference 



A Mill-scale Study of Western Yellow Pine, H. E. McKenzie, Bui. 6, Cali- 

 fornia State Board of Forestry, Sacramento, Cat, 1915. 



75. The Massachusetts Log Rule for Round-edged Lumber. This 

 log rule is constructed for round-edged and square-edged boards as 

 sawed from small logs for close utilization of second-growth timber. 



The per cent of square-edged lumber sawed varies from to 50 per cent, increas- 

 ing with diameter of log. The rest of the cut was round-edged. The rule is for 

 i-inch saw kerf, varying in the per cent of round- or square-edged boards included. 

 It is based on mill taUies of 1200 logs down to 4 inches at small end. The rule is 



