190 THE INCRF,:\rp:NT. 



Again, the approximate value — 



S — s 200 



Section IV. — Addition of the several Increment 

 Per Cents, leading to the Forest Per Cent. 



Instead of calculating with the volume-, quality-, and price- 

 increments separately, it is more convenient to combine 

 them. The combined increment per cent, is determined in 

 the following manner : — 



A forest, which has at present a value = ;r, increases during 

 the next year — 



In volume by p^ per cent. 

 ,, quality ,, p.^ ,, ,, 

 ., price „ p, ., 



Its value at the end of one year may be expressed by the 

 formula — 



W= (V X VOp, X 1-Op.^ X 1-0^/,. 



For convenience sake — 



l-Op„ X l-O^^, X 1-Op, is placed = l-Q^v, 



where p/ represents the combined effect of p„ p,„ and p. ; hence 



JV=ir X l-O^v- 



This formula could be used to determine the financial 

 activity of a wood at any time, if it were possible to determine 

 accurately the value increment of the wood for a single year. 

 This, however, is a very uncertain operation ; hence the 

 difference in the value of the crop produced during a series 

 of years must be ascertained, a difference due to the combined 

 effect of volume-, quality-, and price increment during, say, 

 II years. 



