198 



FELLING AND 



at breast height, and the same height, will have about the 

 same volume. 



The diameters at breast height, 4 feet 3 inches from the 

 ground, are found by using callipers made of wood, which are 

 marked with inches and decimals of an inch. These can be 

 easily prepared by any estate carpenter at a small cost. The 



Fig. 15. Friedrich's Calliper. 



Vertical Section of Movable 

 Arm. 



instrument consists of a rule with two arms at right angles to 

 it, one placed at the end being fixed, while the other is 

 movable. The movable arm is pushed towards the end of 

 the rule till the tree to be measured can be clasped between 

 it and the fixed arm. The diameter can then be read off to 

 a tenth of an inch. Where large numbers of trees are to be 

 measured the work can be done far quicker by taking the 

 diameter with callipers than by taking the girth with a tape. 



