FORM-FACTOR IN CONIFEROUS TREES. 



147 



form-factor will therefore be, say about -350. In Fig. 14 the 

 height of the tree is 17 feet and the base of the tree-point lies 

 halfway up the cylinder, and, assuming that the surplus below 

 breast-height is equal to the deficit in the cylinder between it 

 and the base of the tree-point, the volume of timber in the tree 

 is equal to that of half the cylinder and the form-factor becomes 

 •500. In Fig. 15, with a slightly larger tree, the surplus volume 



FqTI 



ri(;1t. 



ri(ii3. 



TicH. 



T,q.1S 



Fk;.'.6. 



F,c; 17. 



Fiq.ie. 



of the tree below breast-height is less than the deficiency above, 

 so that the timber volume of the tree falls below that of half 

 the cylinder, and the form-factor is less than '500. 



In Fig. 16 a relatively larger tree is shown, which resembles 

 Fig. 6 in that the basal area of the cylinder at breast-height and 

 of that at the ground are nearly the same, while the tree-point 

 is but a small part of the total height. The timber volume of 

 the tree, therefore, approaches one-third of that of the cylinder 

 and is, approximately, "300. This form-factor is, therefore, not 

 a true expression of form. It increases with size from coco to 

 •500 and decreases thereafter to about '300. 



Fig. 19 shows graphically how these four types of form-factor 

 vary with size. 



