

ESTIMATING STANDING TIMBER. Loe 
Add together the results thus secured for the total amount of tim- 
ber in the two-log trees. Make a similar calculation for the three- 
log trees, the four-log trees, etc. Then add together the total 
contents of the two-log, three-log, four-log trees, ete., for the total 
amoun¢ of timber on the area. 
Another method is to estimate the total height of each tree 
when measured and to group the trees in height classes as follows: 
WHITE PINE. 
oa) 
Diameter | Under 60| 60to 80 | 80 to 100 
100 t0 120 | Over 120 | 
breasthigh. feet. feet. | feet. 
| 
feet. feet. | 
a 
The total amount of timber on the area may be determined in 
the way described on page 126, if volume tables exist which give 
the contents of average trees under 60 feet, 60 to 80 feet, 80 to 100 



Romecwe i et 
| 

feet, etc., in height. 
If no such tables exist but there are tables for trees of all 
heights, the cruiser should measure in the woods the average 
heights of trees under 60 feet, 60 to 80 feet, 80 to 100 feet, etc. 
He should then compute the average diameter of the counted 
trees under 60 feet, 60 to 80 feet, 80 to 100 feet, ete. Knowing 
the diameter and the height of the average tree under 60 feet, 
its content is secured from a volume table of heights and diam- 
eters. This value is then multiplied by the number oi trees 
under 60 feet in height. The contents of the trees 60 to 80 feet, 
80 to 100 feet, etc., are found in the same way, and the totals are 
added together for the total amount of timber on the area. 
The most accurate method of using heights in cruising is to de- 
termine the average heights of trees of different diameters in the 
following way: After the trees on a sample acre have been cali- 
pered in the usual way the heights of a limited number of trees 
of different diameters, including small, medium, and large trees, 
- are measured. Generally three to ten trees for each species are 
measured. The cruiser selects for measurement trees which ap- 
pear to him to be of average height in their class, whether small, 
