4 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 



A very prevalent form of table determines the relative doses in 

 proportion of the product of the two dimensions. Thus a tree 30 x 

 30 ft. would have the same dose as one 21 x 42 ft. This is evidently 

 only a mathematical blunder and is about equivalent to insisting that 

 a man six feet high and three feet waist measure weighed the same as 

 another man four feet around and four and one half feet high, since 

 the product in each case is 18. 



The inaccuracy of this method of calculating is perhaps better 

 shown by the accompanying diagram (Fig. 1), in which the difference 

 in size is very evident to the eye. 



Fig. 1. Extreme shapes of trees. Those at the left are of 

 equal size and should receive equal doses. Those at the right 

 receive the same dose by the common tables but one is a third 

 larger than the other. 



The distance over the top is the most significant dimension since 

 it varies with changes either in height or width. Every foot of decrease 

 of this dimension requires approximately four feet of increase in 

 circumference to maintain the tree of the same size. This is true 

 whether the calculations are made on .the basis of cubic contents or 

 of tent area. 



The dimensions corresponding with each foot change in distance 

 over are as follows : 



30 x 30, 29 x 34, 28 x 38, 27 x 42, 26 x 46, 25 x 50. 

 This is very different from the common figures : 



30 x 30, 29 x 31, 28 x 32, 27 x33, 26 x 35, 25 x 36, 24 x 37, 23 x 39, 



and 22 x 41, 

 which are in no wav defensible and should be discarded. 



II. SIZE 



The writer acknowledges the responsibilitj^ of having first suggested 

 the method of size calculation now in vogue, though it had previously 

 been used unconsciously by the late Alexander Craw and some who 



