528 



APPENDIX 



RESULTS OF BORINGS WITH PRESSLER'S INCREMENT BORER 

 Number of years to pass from one diameter class to another 



The 35 trees take in the aggregate 539 years to pass from one diameter class to an- 



539 



other or an average of -== = 15.4; that is to say in 16 years all the stems should pass 

 oo 



through one diameter class (2 inches); the length of the cutting period is therefore 

 justified. The curve given below brings out this point even clearer: 



