56 



VOLUME OF WHOLE WOODS. 



Urick's method is thus a combination of Draudt's method 

 with that of the arithmetical mean sample tree for each group. 



The degree of accuracy depends on the number of groups 

 which are formed, and on the number of sample trees 

 measured in each. Too large a number of groups is however 

 inconvenient, as it involves repeated separation of the original 



diameter classes. 



CALCULATION OF VOLUME, 



