98 THE WOODSMAN’S HANDBOOK. 
INSTRUMENTS FOR MEASURING HEIGHTS. 
There are several methods of determining the height of a stand- 
ing tree. One of the simplest is to measure the shadow of the tree 
and the shadow ofa straight pole of known length set perpendicular 
to the earth. Multiply the length of the shadow of the tree by the 
length of the pole and divide the product by the length of the 
shadow of the pole. The result will be the height of the tree. 
A method used when the sun is not shining is to set two poles 
in a line with the tree. (See fig. 6.) From a point on one pole 
sight across the second pole to the base and to the top of the tree. 
Let an assistant note the points where the lines of vision cross the 
second pole and measure the distance between these points. Also 
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Fic. 7.—Measuring the height ofa tree by use of known height to eye of the observer. 
measure the distances from the sighting point on the first pole to | 
the base of the tree and to the lowest vision point on the second 
pole. Multiply the distance between the upper and lower vision 
points on the second pole by the longer of the other two measure- 
ments and divide by the shorter; the result will be the height of 
the tree. 
Example: Let ab=6; Sb=4; and SB=30; then 
of tree. 
Another method sometimes used is as follows: The observer 
walks to a distance from the foot of the tree about equal to its | 
estimated height. He then lies on his back, stretched at full — 
length (fig. 7), and an assistant notes on a vertical staff erected 
Ex a, height 
