FOREST EXPLOITATION. 23 



found that, though continuing to make increase, it does 

 not make a greater increment between 60 and 70 than it 

 did between 30 and 40, and that, though still making 

 increase, this is now in continuously diminishing quantity, 

 until decay having begun after a lapse of years, it loses 

 more by decay than it makes by growth. But it may be 

 found that though the rate of increase of quantity was 

 reversed after 60 years of growth, the quality continued to 

 improve for thirty years and more thereafter ; and also 

 that it was only when the tree had attained the age of 150 

 years that it had attained the size necessary to yield timber 

 of the size required for some special purpose for which it 

 was needed. All of the information thus obtained may be 

 turned to account in determining the treatment to be 

 given to the forest in exploitation, though it may, or it may 

 not, all be required ; but the same may be said of a great 

 deal of the work of subordinates in any work. 



In the hypothetical case supposed, it might be necessary 

 to secure some timber of the greatest bulk which could be 

 obtained, and in order to this, that the trees yielding this 

 should grow to the age of 150 years. But it might be 

 desired rather to get as much wood from the forest as 

 possible ; and much more would be obtained in the course 

 of 300 years by felling at the age of 75, and getting four 

 crops of trees of that age than by felling all at 150, and 

 getting two crops of trees at that age. By felling at 60, 

 and leaving baliveaux for seed, several fellings of trees 

 aged 90 the age at which the trees yielded timber of the 

 best quality and fellings at the ages of 120 years, and 

 180 years, and 240 years, and 300 years, of timber of 

 greater magnitude might be obtained, along with the cop- 

 pice wood of six fellings in the course of 300 years, from 

 baliveaux left growing at the first, the second, and the 

 third successive fellings ; which might be reserved exactly 

 in such numbers as would yield the timber required and 

 the rapid growth of none of the others at an earlier age 

 would be sacrificed. Or, again, it might be desired to get 

 as large pecuniary returns from the forest as possible ; and 



