THE BILTMORE STICK 
301 
THE BILTMORE STICK 
This implement, employed to ascertain the diameter of 
standing timber when held at arm’s length tangent to the 
trees to be measured, was briefly described on page 163. 
Relations between tree, stick, and eye when the stick is 
in use are made clear in the figure, the circle representing 
a section of a tree breast high, B X the Biltmore stick, 
A T the distance from the stick to the eye, and 0 M a 
radius vertical to the line of sight passing on one side of 
the tree. With this for a pattern it is clear how the woods¬ 
man, after having determined A T as a matter of practice, 
can plot circles of different diameters, draw tangents to 
them from A, and ascertain by measurement in each case 
B C, the proper stick graduation. 
The geometry of the matter is that of similar right- 
angled triangles, and consideration will show the soundness 
of the formula appended, from which may be derived 
BC = 
Vat x d 
AT(AT+D ) 
the value of B C for circles of any size and for any arm 
reach. When the latter, A T, has been determined by 
trial, the formula becomes simpler. Thus with A T = 25 
inches 
B C 
25 D 
V*5 (25 + D ) 
or, for D = 10 inches 
250 
250 
V625 + 250 29 - 58 
= 8.45 inches. 
Values of B C for tree diameters from 6 to 60 inches and 
distances of 23 to 27 inches have been worked out and 
are published in the “Proceedings of the Society of Amer¬ 
ican Foresters” for 1914, page 48. 
