LUMBER GRADES AND LOG GRADES 463 



and defective. Where log grades are used, these grades are also separated. 

 Next, the logs in each separate class are sorted into diameter classes, 1-inch or 2- 

 inch (volume based on differences of 100 board feet was used in the studies conducted 

 in District 1, Missoula, Montana). As a result of this tabulation, the logs when orig- 

 inally classed by the scaler into grades by judgment, can be re-graded in accordance 

 with actual specifications for the grades. A sample form of tabulation would be, 

 by columns: 



Diameter class. 

 Number of logs as a basis. 

 Average lengths of logs. 



Per cent and value per 1000 board feet of each grade, represented in the prod- 

 uct obtained. 

 Total lumber tally, excluding cull lumber sawed. 

 Over-run, excluding cull lumber sawed. 

 Tally of cull lumber sawed. 

 Over-run, including cull lumber sawed. 

 Net scale. 



Per cent of total net scale in each class of logs. 

 Value per 1000 board feet, based on net tally. 

 Value per 1000 board feet, based on net scale. 

 Gross scale. 

 Per cent deducted for defect. 



These data, shown thus for each class of logs, can be totaled for all logs, and 

 averaged. 



7. Deductions or summaries. Irregularities are sure to occur in the final sum- 

 maries. These can frequently be evened off by means of curves. The final curves 

 and tables should show, for each separate log grade, the per cent of each grade of 

 lumber obtained for logs of each diameter class, and the value of the average log for 

 the class. 



Effect of Waste or Cull. Such studies indicate the effect of increasing amounts 

 of waste or cull upon the value of the gross scale or log. Cull lumber may not 

 reduce the sale value of the residual lumber cut from the log, but the cost of log- 

 ging is based upon the actual size of the log, which is best measured by its gross 

 scale. The value of the ])roduct divided by this total scale gives a more correct 

 gage of the value of the whole log in terms of price per 1000 board feet, for the 

 purpose of determining whether the log is merchantable 



A crew of five men can usually tally two hundred logs per day of average 

 sizes. A single mill-scale study requires from one thousand to two thousand logs 

 for best results 



Instructions for Recording Data, U. S. Forest Sernce. Logs should be lettered 

 A, B, C, etc., A being the butt log. The species may be written out or the atlas 

 number may be used, thus: " Loblolly pine" or " P76." The log length should 

 be measured to the nearest tenth of a foot. The crook may be measured by noting 

 the distance in inches between a straight line connecting the ends of the log on the 

 concave side and the log itself. If relative terms such as "" V " (vcr>' crooked), 

 " M " (moderately crooked), and " S " (slightly crooked) are used, they should be 

 carefully defined. Thus, if the crook is more than one-half the diameter of the log 

 the term " V " might be applied; if one-quarter to one-half the diameter it would 

 be ' M ' '; while less than one-quarter it would be " S." If practically straight 

 indicate this by '' O " after heading •' Crook." 



