VII 



CURVES 



The calculations upon which these curves de- 

 pend were made, where area is taken into ac- 

 count (Plates III -VI), on the basis of fully- 

 stocked acres, or acres of density 1. It wiU often 

 be necessary, in using the curves, to make al- 

 lowance for this fact. To do so the density of 

 the group or forest must be estimated by ref- 

 erence to the cover, or forest canopy, as explained 

 on page 61, and the figure given by the curve 

 must then be reduced by multiplication with the 

 decimal by which the density is expressed. A 

 curve is drawn for each one of the three qualities 

 of locality, as explained on page 72. According 

 to the grade of the Pine with reference to which 

 these curves are used, one or another of them 

 must be employed. Correct results will depend 

 very largely on the observance of this caution, 

 and on a proper estimate of the density in each 

 case. 



87 



