92 THE WOODSMAN’S HANDBOOK. 
Table 8 assumes the same rate of growth for the next inch in 
diameter as the last 2 inches (1 inch on radius). It requires a 
measurement of the present diameter excluding bark, and a count 
of rings in the last inch of radius. This is easily done on logged 
trees, but on standing timber it requires that trees be notched to 
at least an inch (or the use of the Pressler increment borer 2) 
to get the ring count and bark thickness. When the diameter 
inside bark is known, and the number of rings in the last radial 
inch, the volume increment per cent is read from the table. The 
error ior rapid-growing trees is not serious when an approximation 
only is required. Of course, a number of trees of each diameter 
should be examined and the average number of rings in the last 
inch used. | 
For a stand of trees the table will apply if the stand is divided 
into diameter classes and examined in that way. There is more 
chance for error if an average diameter is taken for the entire 
stand, unless the variation in diameter is not very great. 
Again, in dense stands some allowance must be made in figur- 
ing volume growth for the loss through the crowding out of some 
of the trees. 
a See page 110 for description of this instrument. 
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