36 THE CONSTRUCTION OF VOLUME TABLES 



3. Find the averago frustum form factor by obtaining the sum of the 



individual form factors of all trees and dividing by the number of 

 trees. 



4. Obtain the volume taV)le by multiplying each volume in the frustum 



table in the Appendix by the average frustum form factor. 



Method IL To construct a volume table with a considerable number of 

 trees. 



1. Compute the frustum form factor as in Method L 



2. Devise a convenient form of tabulation and group the trees into 



5-inch diameter classes. Secure for each class the average frustum 

 form factor. 



3. Round off the values of these average frustum form factors by means 



of a curve. 



4. Obtain the final volume table by multiplying each value in the frustum 



table in the Appendix by the average frustum form factor for the 

 diameter class in which the value is included. 



Note. — Should the table in the Appendix giving the volumes of frustums 

 of cones not contain a sufficient range of values it may be extended by the 

 method illustrated in the following two examples: 



Example 1. To find the volume of the frustum of a cone with 8-inch top, 

 10 inches D.B.H. and H logs in length. 

 Tree: 10 inches D.B.H. with 8-inch top and 1 log in length yields 1 8-inch 

 log containing 32 feet B.M. 



Tree: 10 inches D.B.H. with 8-inch top and 2 logs in length yields 

 1 8-inch log containing 32 feet B.M. 

 1 9-inch log containing 42 feet B.M. 



Total volume. . . .■ 74 feet B.M. 



By Interpolation 



Tree: 10 inches D.B.H. 8-inch top 1| logs in length yields 32 + K74-32) = 

 43 feet B.M. 



Example 2. To find the volume of the frustum of a cone with 8-inch top, 

 16 inches D.B.H. and 4 logs in length. 



Total taper = 8 inches. Taper per log = 2 inches. 



Tree yields 1 8-inch log containing 32 feet B.M. 



1 10-inch log containing 54 feet B.M. 



1 12-inch log containing 79 feet B.M. 



1 14-inch log containing 114 feet B.M. 



Total volume 279 feet B.M. 



