INSTRUMENTS USEFUL TO A WOODSMAN. 95 
The increase in board-foot contents due to growth in loblolly pine 
shows, according to the Scribner Rule, the following relation to the 
erowth per cent in total volume given in the table on page 93: 
Relation of board foot 
Diameter of (Scribner) increment 
the tree. to total volume incre- 
ment. 
Inches. Times. | 
2k 
10 14: 
12 te 
18 4 oe 
24 1 ES 
36 J el) ae 
It is seen that the volume growth per cent, whether taken as 
total tree volume, saw cut, or Beribner Rule, is almost the same 
for trees over 18 inches. 
In addition to growth in volume, trees increase in value with size 
faster than the volume indicates, since there is a greater proportion 
of the better grades of lumber in the larger trees. Thus white pine 
stumpage in 24-inch trees is worth at least twice that in 12-inch 
trees. This is an extremely variable factor, however. 
Again, stumpage tends to increase in price with time, even were 
there no increase in growth. 
To summarize, then, the profitableness of letting trees grow is 
determined by the percentage of wood laid on, the extra increase 
in board-foot product coming with increased size, the larger stump- 
age price paid for larger material, and the constant tendency for 
stumpage to increase even without growth. The first two factors 
may be approximated; the last two can not be dealt with according 
to fixed rules. 
SPECIAL INSTRUMENTS USEFUL TO A WOODSMAN. 
It is unnecessary to describe the instruments which are familiar 
to every woodsman. It is believed, however, that those described 
in the following pages are not generally known, at least in the form 
recommended. They will prove useful in many cases to cruisers 
and other woodsmen. Further information regarding the instru- 
