202 



THE FORM OF TREES AND TAPER TABLES 



With more regular original averages, the curves will coincide very closely with 

 the original data, instead of showing the wide variations indicated in this figure, 

 caused by the great irregularity of the original unharmonized values of Fig. 32. 



The effect of this second plotting upon the irregular forms shown in Fig. 32 is 

 illustrated in Fig. 35, in which the curved or harmonized tapers from Fig. 33 are 

 replotted in the original form. 1 



The values when read from the curves are taken from the ordinates repre- 

 senting exact diameter classes. This set of curves therefore is evened off for values 

 of the diameter classes, and progresses regularly by 1-inch or 2-inch diameters. 



Third Set of Curves, Tapers Based on Total Heights of Trees. We 

 now have, first, true averages of the original form of each separate 

 class, second, true averages for exact diameter classes instead of for 

 average diameters larger or smaller than these exact classes. Both 



60 



60 70 



Total height of Tree, feet 



Fig. 34. — Tapers based on total heights of trees. For trees of the same 

 D.B.H. class. 14-inch trees. 



sets of curves deal, however, only with one separate height class. It 

 may happen that the trees of the 80-foot class are all slender, tapering 

 trees, while those of the 70-foot or 90-foot class are more cylindrical. 

 There is no reason why in a general table which seeks average form, 

 the accidental departure of form from the average, by a set of trees 

 in one height class, should be accepted if this deviation can be easily 

 shown and corrected. 



To do this, it is necessary to compare the upper diameters of the 

 trees of different height classes, at the same points on the stem. D.B.H. 

 must therefore be eliminated as a variable and height substituted. 



1 Since height above stump is the basis of curves in Figs. 32 and 35, the tree 

 form is shown as if lying on its side. The diameter, instead of being plotted sym- 

 metrically on both sides of an axis, is plotted on the vertical scale above the base 

 of the figure. But by holding this figure at right angles, the form of the bole is 



