HEIGHT MEASUREMENT 
165 
black and white, which target is fixed horizontally at any 
point desirable at the base of the tree. 
“ The instrument itself consists of a piece of metal about 
18 inches long and lj inches wide, containing a longi¬ 
tudinal slot about i inch wide and 17 inches long. The 
edges of this slot must be strictly parallel. Its actual 
width is entirely irrelevant from the mathematical stand¬ 
point. 
“ It might be stated that any stick or pole, even a walking- 
cane, having parallel edges, will answer the purpose of 
establishing and measuring upper diameters. The Bilt- 
more pachymeter is merely a device convenient to handle. 
“ The observer holds the pachymeter pendulum fashion 
by the hand of the outstretched arm in a position parallel 
to the tree trunk, and moves the instrument backward 
or forward until the edges of the slot cut off even with the 
desired diameter shown on the target. Then, the eye 
following upward along the trunk and sighting through 
the slot, that point on the tree bole is readily obtained 
where the bole cuts off with the edges of the slot. The 
position of this point above ground can be ascertained 
easily with the help of any hypsometer.” 
SECTION III 
HEIGHT MEASUREMENT 
There are many methods of measuring the height of 
trees. As serviceable as any are the following: 
1. Windfalls are often of great assistance in ascertain¬ 
ing the height of timber. 
2. A pole 15 or 20 feet in length may be set up along¬ 
side the tree to be estimated and then, standing some dis¬ 
tance away, the cruiser may run his eye up the tree and 
judge how many times the length of the pole will be con¬ 
tained in it. A pencil held erect at arm’s length in range 
of the pole and then run up the tree will help the eye in 
making the judgment. 
3. A cane or staff may be used on the principle of similar 
triangles. Hold the staff firmly in the hand with the arm 
straight and horizontal. Swing the end of the staff down 
