MEASUREMENT OF THE DIAMETER INCREMENT. 13 



If no section is available, as in the case of standing trees, 

 the measurements are made with Pressler's Increment Borer 

 (Fig. 6). This instrument extracts a cylinder of wood from 

 the stem, and it consists of the following parts : 



(a) A hollow borer, A, which is slightly conical from the 



handle towards the point. 



( b) A handle, B, which is hollow and serves to receive the 



Fig. 6. Pressler's Increment Borer. 



borer, wedge and cradle, when the instrument is not in 

 use (see E in figure). 



(c) A wedge, C, which has a scale marked on one side 



wherewith to measure the breadth of the concentric 

 rings, and is roughly toothed on the other side to assist 

 in extracting the cylinder of wood. 



(d) A cradle, D, into which the cylinder of wood is placed, 



after extraction, to prevent its breaking. 



The borer is used in the following way : 



It is screwed in a radial direction into the tree, at right 

 angles to its axis, to the desired depth, whereby a C} 7 lindrical 

 column of wood enters the hollow borer, which is severed from 

 the tree except at its base ; then the wedge is inserted between 



