-252 



The utilization per cent, must fall with the increase of r, 

 just as the increment per cent, has been shown to fall. 



Example : Table at page 190. 



The greatest volume production occurs under a rotation of 

 40 years, hence : 



n rxl 40 x 2900 KQ nrkrk , . - 

 G n = = 58,000 cubic feet. 



2t _ 



Utilization per cent. = 



72 x 100 



Increment per cent, of oldest age -gradation = - = 2'5%. 



2900 



A somewhat different result is obtained if G n is calculated 

 from the positions of a yield table. For summer 



G n =10 (510 + 1290 + 2140.+ 1450) = 58,900 cubic feet. 

 and 



Utilization per cent. = o ^ = 5-38/ , or more than 20 . 



Calculating the per cent, for various rotations the following 

 data are obtained : 



UTILIZATION PER CENT. 



ROTATION. By Mean Annual From Yield 



Increment. Tables. 



30 ..... G'67 7'46 



40 . . . . . 5* 5'38 



50 ..... 4- 4-10 



60 . . . . . 3-34 3-27 



In this case the two are equal some time between 50 and 60 

 y-ears, after which the per cent, calculated from yield tables is 

 .smaller than that calculated by the mean annual increment. 



