66 NO TES ON FORES TR Y. 



and marketable branches, which, being converted 

 into cubic feet, and added to the measured portion, 

 the total is divided by the contents of the ideal 

 cylinder, the length of which is equal to the 

 total height of the tree, and the diameter equal to 

 that of the tree at base. The quotient is the form 

 figure, generally expressed by two decimals. For 

 example : If a tree 2 feet diameter at base and 

 90 feet high contains 120 cubic feet timber, we 

 divide 120 by 



2 2 x '7854 X 90 = 2827)1 20'00(-42, the form figure. 

 11308 

 6920 

 5754 



We have seen above that a true cone would be 

 represented by the form figure *33, but true cones 

 are rarely found in the forest; the spar tapers 

 irregularly, and specimen trunks should always be 

 cut up into 10-feet lengths and measured separ- 

 ately. The form of all the sample trees being thus 

 severally arrived at, their mean is taken as the 

 form figure of that forest. While the operation 

 is in hand, it is as well to determine the relative 

 proportion of timber and fuel. 



