Form of the Bole of the Balsam Fir. 57 



the stem a neiloid form. At a height of about 11 feet this neiloid 

 form changes over to that of the paraboloid which obtains to the 

 top of the tree, becoming to be sure more and more conical as we 

 near the top, but never quite assuming the form of a true cone. 

 Similar average diameter measurements of stems of other heights 

 indicated in each case the same essential features, viz., that the 

 bole above the neiloid portion at the base is fairly cylindrical up 

 to the middle point, and that beyond this it falls rapidly away to 

 a conical form which terminates in a very long slender conical 

 top, averaging, in the 65-foot trees, 16 feet above the 4 inch 

 diameter point. 



The heavy broken line of the figure represents the average bole 

 of a Norway Spruce of the same height and the same diameters 

 at breast-high and the middle point. ^ It will be noticed that up 

 to the middle point the variation was so slight that it could not 

 be represented in the figure, but that in the upper half of the 

 bole the Balsam Fir is markedly more conical than the Norway 

 Spruce. 



The volume of the bole above the 4 inch point (the un- 

 merchantable portion when cut for pulp) proved to be about 3% 

 of the whole stem in the trees measured. This is noticeably 

 larger than that of the Red Spruce of similar dimensions. As 

 intimated in a previous paper ^ the form factors of all the stems 

 were calculated from the sectional measurements and were com- 

 pared with the form quotient obtained by dividing the breast-high 

 diameter (af) into the middle diameter (S) multiplied by 100. 

 The results for the individual trees were classified according to 

 breast-high diameter, height, form factor, form quotient, and age. 

 The facts brought out by this classification will be indicated 

 briefly in the following paragraphs, and while the small number 

 of trees examined must not be overlooked, the results as far as 

 the data went were sufficiently uniform to induce the belief that 

 they are in the main correct. 



Form Factor: The average form factor for the 94 trees was 

 45.7. That it fell with increasing height, as all form factors 

 based on the diameter at breast-high must fall, goes without say- 



1 Form und Inhalt der Fichte : Adalbert Schiffel. Mittheil. a. d. Forstl. 

 Versuchsw. Osterreicbs. Heft 24. 1899. 

 * Forestry Quarterly, Vol. I., No. i., p. 11. 



