CLEARING THE CROP 159 



Or the tree may be divided into two or more lengths, 

 the length and ^ girth of each taken, and the contents of 

 all lengths added together to give the total cubic contents 

 of the tree. 



The allowance made for bark is usually 1 inch in 12 

 inches (or -ji^) for thick or rough barked trees such as 

 Oak, and | inch in 12 inches (or -Jy) for such thin-barked 

 trees as Beech or Spruce. 



Measuring Standing Timber. 



The measuring of individual standing trees is usually 

 done by judging the height and the girth at half-way, 

 assisted by the use of poles of known length, or by the use 

 of hypsometers or height measurers. When using a pole, 

 which should be jointed and at least 20 feet in length, it 

 is held against the tree, the man measuring standing back 

 where he can see the full height of the bole, judging 

 its height above the pole by comparison with the latter, 

 and adding the known length to the length judged. 



Many kinds of hypsometers are made, but they are all 

 based upon the same principle — viz., that of equal- 

 angled triangles. 



Faustman's mirror hypsometer and Weise's telescopic 

 one are both very similar and easy to work. 



In using the former, a base line is measured from the 

 tree, say 20 yards, and a movable upright arm is set to 

 figures indicating this distance. The observer then looks 

 through an aperture in a small disc at one end and across 

 a hair line stretched across a small frame at the other end, 

 bringing the two points in line with the height to be 



