Table 2 gives a comparison of earnings in different sizes of Idaho -white 

 pine timber,, with the volumes in the table computed on both a board-foot 

 log scale and a cubic-foot basis* When average earnings equal 100, the 

 range in earnings on a board-foot log scale basis is from 55 for small 

 timber to 116 for large, or a spread of 6l units,, On a cubic-foot basis 

 the range is from 63 to 110, or a spread of only 47 units, which is 

 23 percent less than the board-foot basis 



Table 2» Relative earnings o f woods sawyers 

 (Average "earnings =lL O0~~p"ercent) 



Diameter 

 breast high 

 class 

 Inches 



10-13 



14-16 



17-20 



21-24 



25 & up 



¥t« average 



Scribner 

 Decimal C rule 

 gross scale basis 



Pe rcen t 



55 

 75 

 92 

 105 

 116 

 100 



Cubic feet, 

 gross volume 

 basis 



Percent 



63 

 84 

 93 

 105 

 110 

 100 



An Advantage to Scientists 



Where exactness is required, as in scientific work, volumes computed by 

 using board-foot log rules give very uncertain answers 8 Then too, if 

 results must be expressed in terms of a number of log rules, computations 

 must be repeated, which adds to the x*ork 



The uncertainty of answers obtained by using board-foot log rules can best 

 be illustrated by an example The example chosen for illustration deals 

 with the growth of a tree which contains one l6-foot log whose diameter 

 was 6 inches in 1900 and 9 inches in 1930, the rate of growth being 1 inch 

 per -decade, as shown in table 3. Volumes for this tree on a board foot 

 (Scribner Decimal C) basis and on a cubic-foot basis are also shown, as 

 well as the percent of increase in volume, by decades. 



■11- 



