272 Practical Forestry 



When each tree is to be measured separately two assistants 

 will be required, one to carry the 18-ft. pole, and the other 

 the girting-strap. Sometimes, when the timber is of great 

 height, jointed bamboos are used, and a light ladder brought 

 into requisition. 



In carrying out the work in this way, the man with the 

 pole declares the height of the tree, and the one with the 

 tape the quarter-girth. 



Measuring the Height of Trees. There are several 

 methods of ascertaining the heights of trees, but the two 

 following are, perhaps, the most simple, and the appliances 

 necessary quite inexpensive : 



No 1. Take three laths, such as bricklayers use for 

 tiling, and nail them in the shape of the frame shown ; a a 

 must be of equal length ; a and b being placed on the ground, 

 the eye must follow up the larger lath d d until it is in a line 

 with e, the top of the tree or object you wish to measure. 



The frame must be placed as level with the bottom of 

 the tree as possible. Should the ground be very uneven you 

 must give and take accordingly. 



It will be seen that b to c is the same length as c to e, and 

 this gives the height of the tree. 



No 2 . Suspend the triangle between the thumb and fore- 

 finger of the left hand, knuckles down, upon the point a a, 

 allowing it to swing freely. The edge b c will then fall 

 perpendicularly, and c d will be horizontal. The remaining 

 edge d b will then lie at an angle of 45 to the horizon. On 

 this edge are two sights, e and /. Look through e until / 

 is aligned with the tree- top, advancing or retiring till the 

 sights point exactly to it. 



Then, if the observer's feet are level with the tree root, 

 the height of the tree is the distance from his feet to the root, 

 plus the height of the eye from the ground. 



The dendrometer is perhaps the most useful instrument 

 for taking the height of a tree and can be procured from 

 some of our nurserymen. 



