34 



9. Valuation survey hy means of the ris^ii-heigU. 



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 nc/4^height of a suflacient number of sample 

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

 assumed as the r*c^^-height B^ of the whole crop. The contents of 

 the crop are then obtained from the formula 



C=f AH,. + kh^. 

 .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-heighfc 

 classes, and the average ricA^height determined for each class 

 separately. 



10. WUh 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 diflferent girths determined therefrom. The fol- 

 lowing is an example, exhibiting a convenient mode of arranging 

 and manipulating the various figures : — 



