42 THE WHITE PINE 



then a regular falling off. The form factors for 

 the bigger trees are rather large. The latter, 

 in nearly all cases, were standing in full enjoy- 

 ment of light and growing space, and their 

 trunks had correspondingly little taper. Fur- 

 thermore, the largest trees are some 250 years 

 old, while the smallest are from 100 to 150 years 

 younger. 



The values in Table I were obtained by the 

 use of the form factors. The volume in each 

 case is equal to the product of the basal area 

 by the height multiplied by the form factor 

 corresponding to the diameter of the tree. 



In order to test the accuracy of the form fac- 

 tors, the trees actually measured were thrown 

 into diameter classes of two inches, and the 

 average heights were obtained for each diame- 

 ter class by means of a plotted curve. The vol- 

 ume was then computed by the use of the form 

 factors, and the result compared with the actual 

 measured volume of the trees. The error was 

 only 2 per cent. 



