224 



FRUSTUM FORM FACTORS 



TABLE XXXVII 

 Actual Average Top Diameters of Merchantable Lengths, Longleap Pine, 

 Coosa Co., Ala. Basis 555 Trees; Average op All Top Diameters 13.2 

 Inches 



Merchantable Length in 16-foot Logs 



Of the two methods, the use of a fixed top diameter is preferable 

 wherever utilization does not depart too far from this standard. If 

 necessary, such a table of volumes could be corrected for actual utili- 

 zation, by subtracting the per cent of volume lost by cutting to a lower 

 point and larger diameter. In this case the same method must be used 

 in estimating the standing timber, namely, to tally the heights of the 

 trees to the fixed top diameter used, and then discount for waste. 



185. Construction of the Volume Table from Frustum Form Factors. 

 A Short Method. The third and final step is to construct the volume 

 table by multiplying the volumes of the frustums by the form factors 

 for each class, 



