106 



DETERMINATION OF THE INCREMENT. 



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1.0 to -50 HQ 50 Co lo go So 100 ixo 120 



Fig. 37. Graphic representation of the Number of Trees per Acre. 



volumes given in the tables for the same age and the different 

 quality classes. If it agrees with one of these volumes, the 

 two are of the same quality class, and the increment shown in 

 the table applies also to the wood in question. 



If the volume of the wood does not agree with any of the 

 volumes in the tables, then that quality class is selected 

 which comes nearest to it, and the increment is ascertained in 

 proportion to the two volumes. Let v a be the present volume 

 of the wood, V a the nearest volume given in the table ; V a + n 

 the volume given in the same table for the year a + n ; and 

 v a+n the desired volume of the wood in the year a + w, then 



