152 THE FINANCIAL RESULTS OF FORESTRY. 



1. Deter mination of tlie Profit of Forestry, 

 a. Calculaiion for fJie Infrnuiflent WorJciiif/. 

 In the case of a single wood, of approximately uniform age, 

 the returns and costs do not occur at the same time, but at 

 intervals of various duration ; hence, tliey must be calculated 

 for one and the same time. In the first place, that time shall 

 be the commencement of the rotation, when the are.i is about 

 to be planted, or sown, for the production of a forest crop. 



i. Calculation for a Blank Area. 



Let as before — 



1'. be the final yield occurring in the year r and again in 

 2 X r, 3 X r, and so on for ever ; 



Ta, T^ , . . J\, the thinnings occurring in the years 

 a . . . q, and again in a + r . . . q -\- r years, 

 again in a -\- 2 X r . . . q -\- '2 X r years and so on ; 



Sc the cost value of soil ; 



E the capitalised annual expenses = -^ ; 



c the cost of formation expended now, and again every 



r years ; 



c X I'Od' 



C the capitalised cost of formation = — ; 



I'Ojf — 1 



J) the per cent, at which mone^' can be made available for 

 investment in forestry', and at which money taken out 

 of the forest can be invested with equal security. 



Then the present value of all returns is — 



_ i; + r„ X 1-0/-" + • • • + r, X 1-Op-" 



l-Ojf - 1 

 while the present value of all costs comes to — 



Hence, the profit of forestry is expressed by the formula — 

 Profit = P = Y, + T,xrOp-- +^ . . + T, X I'Op-^ 



lop' — i 



- (S, + E + C). 



