EXPECTATION VALUE. 137 



For a rotation of 80 years : 



45 G e = 891 shillings. 



For a rotation of 90 years : 



2789 + 67 x l'025 40 +86 x 1'025 30 +91 x 1-025 20 

 45r +95 xl-025 10 - (250 + 120) (1'025 45 -1) 



1-025 45 



= 878 shillings. 



The maximum value is obtained for a rotation of 80 years, 

 that is to say, the rotation under which the expectation value 

 of the soil culminates (see page 129). 



Assuming now that the wood has been injured by wind at a 

 previous period, so that no thinnings can be made before the 

 year 90, and that the growing stock would realize 



At an age of 70 years . . = 1200 shillings. 



80 . . . . = 2000 

 90 " =2789 



then the expectation value of the wood under these rotations 

 would be as follows : 



For a rotation of 70 years : 



For a rotation of 80 years : 



tSGf = 2000-870^26^1) 

 1 025 



For a rotation of 90 years : 



For a rotation of 100 years : 



It will be observed that the maximum expectation value of 

 the growing stock is, in this case, obtained under a rotation 

 of 90 years. 



