FOREST commissioner's REPORT. 



27 



have been earefally worked up, and the tables proved, for 

 our trees and conditions, approximately true. A better 

 statement of the case would be to say that the tables are all 

 rit>-ht, based on exact measurement and calculation ; what 

 has been done here is simply to find out how to work with 

 them. 



In the course of mv season's cruisino; several men 

 have been met who on hearing of these tables have 

 expressed the greatest interest and been provided 

 with copies at their own request. Anticipating the 

 same interest on the part of others, an extract 

 embodying those figures which have proved best 

 adapted for use on our cut-over spruce lands is 

 here given. 



For use, these tables must be accompanied by 

 the followino- rules : Cut into the tree somewhere 

 from four to five feet from the ground, avoiding 

 any bunches or depressions in its surface, and 

 measure the thickness of the outer ten rings. 

 Measure the diameter of the tree at the same 

 heiirht and make a fair deduction for bark. Into 

 the diameter of wood so obtained divide twice the thickness 

 of the rings, and find the number so obtained in column 1. 

 The number opposite in column 2 is the desired rate per cent. 



Thus su})pose a tree measures thirteen inches in diameter 

 four and one-half feet from the ground, and the outer ten 

 rin<>:s at that height measure three-eighths of an inch, or 



~ "^ CD ' 



approximately .4 inch, thick. Twice that thickness, or the 

 growth in diameter in the last ten years is .8 inch. Now in 

 a thirteen-inch spruce an inch is a liberal allowance for the 

 bark on both sides, so that the diameter of the tree for this 

 purpose is twelve inches. 12-i-.8 is 15, and 15 in column 1 

 stands opposite 1.6 in column 2. The tree then for the last 

 ten years has been growing at the rate of 1.6 per cent com- 

 pound interest. As to the accuracy of results ol)tained by 

 use of these tables it should be said that single trees may 

 depart widely from them. It is designed for use on consid- 



