34 



9. Valuation survey by means of the v\c\\t-Iteight. 



The lower girths of all the trees of the crop being known 

 from the enumeration survey, the total basal area A is calculated 

 therefrom. Next the rzc^-height of a sufficient number of sample 

 stems should be observed, and the average of all these figures 

 assumed as the rtcM-height Ii, of the whole crop. The contents of 

 the crop are then obtained from the formula 



C=l AH r + Afi . 



The contents of the branches must be added as a percentage, 

 which must be taken from tables, or deduced from the results of 

 previous surveys of similar crops. 



The crop may of course be divided into girth-and-height 

 classes, and the average ric4l-height determined for each class 

 separately. 



10. With the aid of tables of form-factors or volumes. 



The girth of all the trees of the crop are already known from 

 the enumeration survey. The heights of a sufficiently large num- 

 ber of trees must be measured, and the average heights which 

 correspond to different girths determined therefrom. The fol- 

 lowing is an example, exhibiting a convenient mode of arranging 

 and manipulating the various figures : 



