VOLUME TABLES 41 



tiplied in order to obtain the volume of the tree. 



On account of the taper, the volume of the 

 tree will be less than that of the cylinder, and 

 therefore the form factor will be a decimal. 



If a is the area of the base, or the area of 

 the circle corresponding to the diameter, the so- 

 called basal area ; 



h the height of the tree j 



y the volume ; and 



/ the form factor ; then 



In this way the form factor was calculated 

 for each tree ; the stem alone, with the bark on, 

 being taken into account. 



With the increase of diameter the form fac- 

 tors decrease. With trees of the same diameter 

 no variation in the form factors occurred with 

 increase in height sufficiently regular to permit 

 the formulation of a law. It was necessary, 

 therefore, to accept the average value of all 

 the different heights corresponding to each 

 diameter. 



The form factors are given in the right-hand 

 column of Table I, and are seen to vary from 

 .508 to .420 as the diameters grow larger. 

 There is at first a slight increase to .512, and 



