96 



CURVES 



CURVES FOR THE MERCHANTABLE YIELD OF 

 WHITE PINE GROUPS, IN CUBIC FEET. 



This Plate gives the total cubic contents of all 

 the logs of merchantable size which conld be 

 cut from a fully stocked acre, at different ages 

 and on different grades of locality, on the basis 

 of the present practice of lumbermen. It should 

 be remembered that the limit of size of mer- 

 chantable logs is continually sinking. The most 

 conspicuous fact which may be learned from 

 this plate is that the yield begins at 40, 50, and 

 60 years respectively for the three grades of 

 locality, although it is at first so small as to be 

 of very moderate importance. But after the 

 yield has once begun the rise is rapid and long 

 sustained. Thus at 50 years a fully stocked 

 acre of quality II will yield 1,100 cubic feet of 

 merchantable timber. At 100 years it will yield 

 5,500 cubit feet, at 150 years 7,700, and at 250 

 years nearly 10,000 cubic feet. 



