62 FOREST VALUATION 



Multiplying numerator and denominator by i.op n X i.o/> n< , 



Jt _/(.^--.)..or-. 



(i.op n i) i.op n 

 This formula is also derived from Formula VII by discounting 



the final value to the present (II), substituting for 



i.op nt i.op n 



Formulae V to VIII are seldom used in forest valuation 

 (82). 



86. Present, Expectation, or Capital Value of Perpetual 

 Rentals. Under the assumption that a rental is perpetual 

 (80), the intermittent rental r, payable every n years, forever 

 will have a future value equal to infinity (oo). 



Its present value (Q 4 ) is 



(IX) 



If the first rental is paid in the year a instead of at n years, 

 as in case of revenue from thinnings, the present value of the 

 sum of a perpetual series due every n years thereafter (Q 4 ) is 



g ~ i.op a ' 

 i 



