THE THEORY AND PRACTICE OF WORKING PLANS 9 



The rotations used were those given in table 6, p. 447 of the 

 article cited. Premise: 100,000 acres of Douglas fir in western 

 Washington. 



COMPARISON OF TWO METHODS OF DETERMINING nv 



1 For B it is necessary to find even decade values and then take proportional part of the 

 difference. 



From this table one might conclude that the formula values 

 should be reduced by 20 per cent, i.e., multiplied by .8, since 

 summation is undoubtedly the more accurate method of the 

 two. 



Many authors have busied themselves with the problem 

 of how to determine the normal growing stock most accurately 

 and have suggested certain departures. Thus Flury * claims 



that the formula, nv = — to be more generally correct, should 



read: 



nv^cXrXi, 



in which c is a variable constant. To determine this constant, 

 normal yield tables are necessary which may be summed up 

 by the formula 



nv = n\ a-\-h-{-c 



. +- 



* Schweizerische Zeitschrift fur Forstwesen, March, 1913, briefed For. Quart. 

 Vol. XIII, No. I, pp. 108-113. 



