19 
Timber averaging four inches would have no value in the 
same industry. 
It will be observed that prices rise for each inch class by 
gradually decreasing increments and proceed to a limiting 
value. The increases in value when the boards become wide 
are very small, and are neglected commercially. The law 
underlying the increases in value appears to be that the in- 
crement in value from one inch class to another is approxi- 
mately a definite fraction of the difference between the value 
of the lower class and the maximum or limiting value. This 
fraction appears to be about one-half. For example, if the 
maximum value of oak is $60 a thousand, and the price of 
six-inch be $40 then the value of the seven-inch would be 
$50 a thousand. 
D. AVERAGE WIDTHS AND VALUES OF YIELDS 
Since increase of the average width of the lumber is the 
important factor in value, it is of interest to know what 
average width of 23” plank each diameter class of tree will 
produce. In Table XI is given the average width of ash 
lumber sawn 23” with 12” sidings. 
Loeally, all good grade lumber is cut into planks with a 
thickness of 2” and over. The 22” is surveyed as 2” and the 
12” sidings as 1”. For thickness 2” and over the price does 
not vary. 
TABLE XI. ASH 
D.B.H. Av. Width Board Feet 
Inches of 2)” Per Acre 
8 4.9 28,600 
9 5.5 26,800 
10 6.1 23,600 
11 6.7 24,000 
12 7.3 22,400 
13 7.9 22,100 
The board feet per acre include the sidings and the per- 
centage of sidings increases with decrease in the diameter of 
the log. As it was found impossible to obtain a series of 
