A NEW LOG RULE. 



In the last issue of the Forestry Quarterly there appeared 

 a new log rule called by the author, Dr. J. F. Clark, the Inter- 

 national Log Rule. 



This rule is undoubtedly the most nearly accurate that has 

 yet been proposed and it is to be hoped that it will soon become 

 generally adopted. It is almost incredible that the Doyle and 

 Scribner Rules should have been kept in use so long since they 

 are so glaringly inaccurate, especially for the smaller sizes of logs. 

 When first brought out they were approximately correct for the 

 sizes of logs and methods of milling then in vogue, but now, 

 when smaller logs are used and greater economy exercised in 

 milling they under-scale frequently 100 to 140 per cent. 



The International Rule was first worked out mathematically 

 and after allowances had been made for taper, shrinkage in 

 seasoning, saw kerf, and crook it was tested at a mill in the 

 Ottawa Valley on a large number of logs, just as they happened 

 to come to the mill. 



As the following table shows, the error of this rule is negli- 

 gible while those of the other rules used were very serious. 



Over-run ( + ) or under-run (-) of Saw Cut, as compared 

 with scale by 



DIAM OF 

 LOGS. 



6 -8 



7 -9 

 8-12 



10-17 

 18-20 

 21-24 

 25-33 



NUMBER 



OF LOGS. DOYLE. SCRIBNER. 



INTERN AT N L 

 CHAMPLAIN. 1-8. 



28 



54 

 101 

 104 



90 

 126 



31 



+ 143% 

 + 115% 

 + 72% 

 45% 

 24% 

 18% 

 10% 



+ 35% 

 + 34% 

 + 23% 

 + 14% 

 + 14% 

 + 9% 



The formula upon which this 



10.3% 



+ 8.8% 

 + 7.1% 

 + 4.7% 

 + 6.7% 

 + 5.2% 



rule is based is 



+ 2.6% 

 + 2.3% 

 + 0.0% 



-1.1% 

 + 0.5% 



+ 1.1% 

 -0.5% 



(D-^ X .22) 



— .71 D. The measurement is made at the small end of the log 

 and the content is figured on the basis of an 8 ft. log in order to 

 prevent the injustice of disregarding the large amount of material 

 which can be cut from the slabs on a long log. 



It includes all square edged boards which have a content of 

 2 feet board measure or over which can be cut from sound logs ; 

 in other words, boards which do not fall below the following 

 dimensions: — 



3 inches wide and 8 feet long. 



4 .' << << 6 " "^ 



5 inches wide and 5 feet long. 



