NATIONAL FOREST MANUAL TIMBER SALES. 



53 



grading rules will assist him in determining where to draw the line 

 between merchantable and unmerchantable timber. 



Under uniform center or circular rot may be included circular 

 " heart rot" or any dote that may be roughly included 

 cirYSl^t 6611 * 61 r within a circle on the cross section showing at either 

 end of a log, making all of the log within the circle 

 unmerchantable. In sawing, this area of defect is squared. The 

 accompanying table shows the amounts of lumber which are lost in 

 defects of this type, in diameters of 2 to 12 inches in the more common 

 log lengths, and which should be deducted from the full scale of the 

 log. Amounts for shorter or longer logs can be obtained as follows: 

 For 6 or 8 foot logs, deduct one-half the amount of loss, which is the 

 same for defect or a given diameter in a 16-inch log as in one of 30- 

 inch diameter. 



The actual loss caused by uniform circular rot as shown by the dia- 

 gram, is also shown in accordance with the rules of adding 2, 3, and 4 

 inches, respectively, to the diameter of the defect, and deducting from 

 the full scale of the log an amount equal to the contents of a log of the 

 resultant diameter. 



By referring to the table it will be seen that the following rules can 

 be used to obtain the desired results : 



For uniform defect 3 inches or less in diameter deduct 10 feet b. m. 

 in logs up to 16 feet in length. 



For defect 4 to 6 inches in diameter add 3 inches to actual diameter 

 of rot, and deduct from the full scale of the log an amount equal to 

 the contents of a log of the resultant diameter. 



For defect 7 to 12 inches in diameter add 4 inches to diameter of 

 rot and deduct an amount equal to the contents of a log of the result- 

 ant diameter from full scale of log. 



Only experience gained by actually seeing defective logs "opened" 

 at the saw will enable sealers to judge how far into a log defect extends 

 when it appears only at one end. 



In short logs showing defect less than 4 inches in diameter at only 

 one end and not in the knots deduct one-half the amount called for by 

 the rule for the full length of the log. 



In measuring the diameter of this type of rot the sealer should 

 measure it at the end of the log showing the greatest area of defect, 

 since the saw cuts in straight parallel lines. 



