216 PUINC'IPLKS OF AMEKICAN FOUESTKY. 



board measure, worth $3 = $18 per acre plus value of soil, 

 worth So per acre. 



2. The yield under forestry is 4,000 feet, worth $3 =$12 

 per acre to be derived at once, and 300 feet, worth 90 cents, 

 to be derived annually thereafter, being the annual produc- 

 tion of the 2,000 feet left standing, per acre. The future 

 yields are to be discounted at (x per cent. —2 per cent.). 



3. The annual expenses, under forestry, are 20 cents. 



The extraordinary expenses are 84 per acre, spent at the 



first cutting. 



90 20 



Equation: 18 + 5=12+ ^ ,, " ,,„.-, — ~ 4. 



0.0 a;— 0.02 0.0 a; 



Result: About 7 per cent. 



