io6 



NOTES ON FORESTRY. 



each of which, if the timber be not exactly of 

 uniform age throughout, trees of approximately 

 uniform age will nevertheless preponderate. 



Here the groundwork of the operation would 

 be the division into blocks, and the classification 

 of the areas of trees of the preponderating age 

 of each block above or below their true place 

 in the rotation ; and the amount of departure from 

 a just proportion of trees of all ages would be 

 rectified in the course of the first rotation by fell- 

 ing a greater or less area above or below the age 

 fixed as the length of the rotation. 



Let us suppose, for example, that stock has been 

 taken of a forest of 120,000 acres in extent, the 

 proper period of rotation being fixed as 120 

 years, and that the returns per area, based on 

 the preponderating trees of each block, are as 

 follows : 



Now, in the first period, having only 10,000 

 acres, we supplement it with 10,000 of the second 

 period, in which we shall then have 40,000, one 



