86 Forestry Quarterly 



slabs. The rules of the National Hardwood Lumber Association, 

 the Louisiana Cypress Association and other similar bodies, have 

 set the minimum dimensions of boards entitled to pass inspection 

 and measurement in the case of most species at 3 inches in width 

 by 4 feet in length. Using a minimum unit of just double this 

 size I found that as logs were cut for ordinary commercial pur- 

 poses in the mill in which I made my tests, an increase in the 

 average major crook of one inch per twelve feet increased the al- 

 lowance required for edging . i foot board measure per square foot 

 of bark surface. With a minimum unit of 3 inches in width by 

 12 feet in length the additional waste in edging for the same 

 increase in average crook was just three- fold or .3 foot board 

 measure per square foot of bark surface. 



As already noted, there have been four log rules — Baxter, British 

 Columbia, Universal, and Champlain — which have had the allow- 

 ance for edging provided for in a rational way. In computing 

 the International Rule the allowance for edging was in all cases 

 made proportional to the circumference at the middle of the logs 

 and hence is strictly proportional to the bark surfaces. This dif- 

 fers somewhat from the method adopted in the computation of 

 the Universal and Champlain rules, where the allowance is pro- 

 portional to the top end circumference, and somewhat more from 

 that used in the computation of the Baxter and British Columbia 

 rules, where the allowance is a certain depth beneath the bark. 

 Both these latter methods — and more particularly the last — give 

 a relatively higher scale for the smaller logs. 



Re Computation a7id Formula. The simplest mathematical for- 

 mula for the International }i Rule is (D'^x .22) — .71D for 4-foot 

 sections. Taper ^-inch per four feet lineal. The .scaling score 

 has been computed for logs from 3 to 60 inches in diameter and 

 from 8 to 20 feet in length, longer logs to be measured as two or 

 more logs. After computation the scale for the individual logs 

 was, at the suggestion of Mr. Price of the Forest Service, rounded 

 off to the nearest 5 or o. The .saving thus affected in the clerical 

 labor of computing tallies is from yi to yz, while the liability to 

 error in multiplying and adding is reduced to a minimum. Any 

 error due to the rounding off is of course absolutely negligible 

 where more than a dozen logs are measured. 



TAe Adapting of Log Rules to Universal Coyiditions. The pro- 

 duct in merchantable lumber which may be sawn from a sound 

 log of given length and top diameter depends on the skill of the 



