NOTES. 



463 



10 SO 30 10 50 60 70 80 80 100 110 120YEAR3 



Diagram showing comparative progress of yields of spruce, fir, pine, 

 and beech, on best and poorest site classes. 



classes may be stated as follows, leaving out the yield in the 

 thinnings, which may amount to as much as 40 per cent of 

 the final harvest : 



By multiplying this average increment by 100, the years 

 of rotation ^or any number of years near that rotation), the 

 total possible harvest per acre is obtained. It appears that 



