
ESTIMATING STANDING TIMBER. 129 
is done in the following way: Take a sheet of cross-section paper 
(fig. 4), lay off on the horizontal lines the diameters, calling each 
small square 1 inch; lay off on the vertical lines the heights, call- 
ing each small square 1 foot. Assume, for example, that the 
following measurements were taken for White Pine: 
Pee ee TREES a Sd ee Se MESA “1953.34 
pe BIC Cha 2 oS Se oS St t3= 80° =935-2114 
Mark on the cross-section paper the point where the vertical 
line running from the diameter point 10 meets the horizontal line 
running from the height point 75. Mark the points of intersec- 
tion for the other diameters and heights in the same way. Then 
draw a regular curve through or as near the points as possible 
in the way shown in fig. 4. The height corresponding to any 
diameter may then be read off from this curve. Thus, to find the 
height of a 16-inch tree, note the point where the vertical line 
running up from the 16-inch point meets the curve; then from this 
point of intersection follow the horizontal line to ascertain the 
height. In the example given the average height of a 16-inch 
tree is 86 feet. 
This method is used to find the contents of sample acres in the 
following way: Make atable of fourcolumns. In the first column 
place the diameters; in the second column the number of trees of 
each diameter given in the first column; in the third column the 
average height of trees of each diameter, these average heights being 
obtained from a curve such as has been described; in the fourth 
column the contents of an average tree from a volume table; in 
the fifth column the total contents of all trees of each diameter. 
Then add the fifth column and the result will be the total con- 
tents of the sample acre. 
27824—Vol. 1, No. 36—02 
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