100 THE MANAGEMENT OF WOODLANDS. 



growth in height with a fair growth in girth, so as to give the 

 best obtainable increment or largest growth in cubic contents. 

 It is therefore only reasonable to expect that neither crowded 

 plantations, which produce long and slender poles, nor over- 

 thinned woods, which produce stems thick at the base, but 

 short and tapering, will give the largest annual increment 

 obtainable from the given soil. 



1. The Measurement of Past Increment on Felled Trees 

 can easily be made by counting the annual rings on cross 



Fig. 25. 



Spill of wood extracted. 

 Pressler's Borer. 



sections, and thus ascertaining the increase from year to year, 

 or in periods of five or ten years. 



2. The Measurement of Past Increment on Standing Trees 

 can easily be made at breast - height with Pressler's borer 

 (Fig. 25), consisting of a hollow handle a, into which fits a hol- 

 low gimlet, 6, for boring into the stem, and a long, flat pin c, 

 toothed inwards towards its head and marked in inches and 

 lines on the convex side ; and both the pin and the gimlet 

 can be packed in the hollow handle, one end-knob of which 



