40 THE WHITE PINE 



sawed from a log. It is a safe guide for saw- 

 mill men, and it underestimates the possible 

 number of feet, especially for logs of small 

 diameter. 



The volume tables are constructed only for 

 trees over 100 years old. As material for these 

 tables we have the analyses of over 100 trees. 

 From the analysis it is possible to compute the 

 volume of a tree at successive ten-year periods 

 during its whole life. Thus, in the case of a 

 tree 200 years old, we can calculate its volume 

 when it was 100, 110, 120, 130, . . . 190, 200 

 years old. Consequently, for the construction 

 of the tables we have the equivalent of eleven 

 trees instead of one. 



It must be remembered that the volume ta- 

 bles represent average values of trees taken 

 from all qualities of soils and localities, and 

 that they are intended chiefly for use in com- 

 puting the volume of large groups. 



A form factor, or coefficient of form, is the 

 relation between the volume of a tree and the 

 volume of a geometrical solid of the same diam- 

 eter and height as the tree. It represents the 

 taper of the tree. In this case the solid is a 

 cylinder, and the form factor is a number by 

 which the volume of a cylinder which has the 

 same base and height as the tree must be mul- 



