MEASUREMENT OF GIRTH. 



95 



is that shown in Fig. 24. The movable leg b is enclosed in a case D 

 in such a way that the fixed scale A has a narrow free space both before 

 and behind, to reduce friction. The base A rests on a metal wedge c, 

 which can be tightened or loosened as necessary by keying it up with 

 the screw d e. 



For scientific investigations extending over several years automatic 

 girth-measurement at breast-height can be secured by placing thin ribbon- 



Fig. 24. 



Best form of Calliper. 



like lead bands round the stem, and tacking them on with small staples, 

 then marking where the outer one's edge overlaps the inner ; and the 

 readings can be made as often as desired (annually or monthly). 



In measuring sample-plots with callipers, two or three men can do the 

 measuring while the forester registers the girth or diameter each calls 

 out, the register varying by 3 in. for girth, or inch by inch for diameter 

 (134 to 14| being graded on calliper as 14 in., and so on). A convenient 

 form of register is 



Lireh. 



LWJ n 



Total. 



17 

 23 

 1!) 



