CALCULATION OF THE VOLUMES OF FRUSTUMS 



223 



form factors vary not with form alone but also with difference in volume 

 due to difference in top diameter independent of form. The results 

 are shown in Table XXXVI where an average top of 13.2 inches was 

 used on all frustums. 



TABLE XXXVI 



Fbustum Form Factors for 555 Longleaf Pines, Coosa Cou^fTY, Alabama, 

 Based on Average Top Diameter of 13.2 Inches for Frustums 



Merchantable Length in 16-foot Logs 



Such a table serves no useful purpose. 



The variation of top diameters actually utilized is shown in Table 

 XXXVII. 



The values in this table, evened off by curves, would give proper 

 dimensions for frustums for the volume table desired. 



The two steps described mean a double calculation of frustum 

 volumes, first, as a basis of regular form factors, second as a basis of 

 regular volumes. The second set of frustums also serves the purpose 

 of obtaining the volumes for exact diameter and height classes, instead 

 of for the actual average diameters and heights of the trees measured 

 (§ 137). 



