149 



CHAPTEK V. 



DETERMINATION OP THE RENTAL OF FORESTS. 



In order to convert any item of income, whether it occurs 

 once or after stated intervals, into an annual rental, it is 

 necessary to ascertain the capital value of the income and then 

 to multiply it by "O^j. For instance, the rental which corre- 

 sponds to the thinning in the year a, and its recurrence every r 

 years, is equal to — 



The annual payment corresponding to the periodic cost of 

 cultivation, is expressed by — 



1. Rental of the Soil. 



By the rental of the soil is understood the annual net 

 return of the soil. It is represented by the difference between 

 the rentals of incomes and the annual payment of expenses of 

 a wood, hence : — 



Soil rental R 



. X 



Op + ^'><^X\-Op + . . . + ^^X'x'Op 



l-Op'-l ' 1-0/ -1 ' ' ' 1-0^/— 1 



VOjf - 1 



This rental, it will be observed, is the rental of the soil 

 expectation value. Soil rental = ''S^ X 'Op. 



