52 BULLETIN 718, U. S. DEPARTMENT OF AGEICULTUEE. 



rule of more ancient origin, which gives the same results, is to deduct 

 4 inches from the diameter of the log as an allowance for sawdust 

 and slabs, then multiply the remainder by half itself, and the product 

 b}'' the length of the log in feet, and divide by 8. The quotient will 

 be the number of square feet contained in the log. Still another giv- 

 ing the same contents is, deduct 4 inches and square the remainder, 

 adding to or deducting for the aliquot parts of a longer or shorter 

 log. 



The Doyle rule gives less values in board feet for IC-foot logs up 

 to 28 inches in diameter than the Scribner or the Decimal C rule, 

 and above that diameter gives gi^eater values. Between 22 and 28 

 inches in diameter, however, there is onlj^ a slight difference between 

 the t"wo rules. The 14 single logs ranging from 8 to 21 inches in 

 diameter scale by the latter rule 12 per cent more than with the Do3de, 

 though logs scaled by the Decimal C rule overrun the log scale by 

 an average of 10 per cent when manufactured into lumber. 



The requirements of the Forest Service call for the measurement of 

 sound material in the log irrespective of grade. Allow^ance is made 

 for bad defects, such as rot, shake, check, cat face, crooks, worm- 

 holes, etc., or a serious combination of one or more such defects in 

 one log. In timber of high commercial value, logs are classed as 

 cull that have two-thirds of the gross scale defective; in the case of 

 inferior species, such as fir, lodgepole, and balsam, one-half of the 

 gross scale. 



It very often happens that timber or logs containing only one-third 

 of the gross scale in merchantable lumber will not pay the cost of 

 handling unless the lumber obtained is high grade. In such cases 

 the scaler should possess a knowledge of grades and be qualified to 

 differentiate between a log that pays for merchandizing and one 

 that does not. 



The only true analysis of what a defective log will scale is found 

 by seeing it opened up in the mill. A scaler's abilit}- to make proper 

 allowance for defect hinges on his experience in this particular re- 

 spect. Defects such as large loose or unsound knots, an occasional 

 knot hole, a great deal of pitch and pockets, some red rot and bad 

 season checks, large wormholes, and any amount of blue stain, unless 

 combined in one log, affect merely the qualit}^ or grade and not 

 the quantity of merchantable lumber produced from the log. They 

 are therefore not recognized as justifying a scaler in discounting 

 the gross scale of a log. 



The fact of logs overrunning the log scale^that is, cutting more 

 board feet than is shown on the Decimal C rule — should not be 

 considered by a scaler in making allowance for defect. This matter 

 of overrun is, in Forest Service sales, taken into account when ap- 



