EFFECT OF ERRORS IN DOYLE RULE 



71 



TABLE X 



Over-run, Doyle Rule. Texas 



The over-run steadily diminishes with increasing diameter until at from 36 to 40 

 inches the rule gives practically full scale for J-inch kerf and normal allowance for 

 slab, disregarding taper. 



An investigation made in 1904 for the Province of Ontario by Judson F. Clark, 

 showed that the volume of the average log cut in the Province had decreased in 

 25 years by 63 per cent and at that time averaged 61 board feet and 12 inches in 

 diameter. From mill tests of pine logs sawed with i^-inch kerf, the per cent of 

 ov«r-run was as follows, for 12-foot logs : 



TABLE XI 

 Over-run, Doyle Rule. Ontario 



When the average log ran between 18 and 31 inches, the defects of this rule were 

 not so apparent, and the over-run was not excessive. But as the size of the logs 

 cut grows less with the advent of second-growth and closer utilization, the rule 

 becomes impossible. Its continued use in many regions is due largely to the fact 

 that logs are not often bought and sold, but the timber is purchased on the stump 

 and the owner is unaware of his losses. This rule must eventually be superseded 

 either by a more consistent standard or by the rejection of board-foot measure 



