60 



MEASrRf]MENT OF WHOLE WOODS. 



As the volume is fairly proportionate to the basal area, Robert 

 Hartig forms groups, which contain equal basal areas. He 

 divides the total basal area of the wood by the number of 

 groups, which he proposes to form ; this gives the basal area 

 to be allotted to each group. After having placed in each a 

 sufficient numl er of trees to give that basal area, he calculates 

 the mean sample tree for each group, and selects an equal 

 number of these for each. 



The formula for E, Hartig's method is as follows : — 



V=r,x''^' + r,X^' + rsX'^'-\- 



As 



^1 'S'2 *S'3 



. are not equal the one to the other, 



Si So S3 



it follows, that the sample trees must be measured and the 



Calclilation of Volume by 



