126 



FOREST commissioner's REPORT. 



Twenty Now confinino; the attention to the spruce, and 



fowhig\^°^' ^^ these to such trees only as are between six and 

 ^^^' sixteen inches in diameter, the problem is to find 



how much of their volume has grown in the last twenty years. 

 Remembering first the rule just established relating to diame- 

 ter growth, we may in the first place say that twenty years 

 ago all trees were on the average (this applies best to those 

 now between ten and fourteen inches) two inches less in 

 diameter. With this figure and the use of Pressler's tallies, 

 or by employing compound interest tables with the several 

 rates per cent which were determined earlier, the volume of 

 the trees at the beginning of the period can be ascertained. 

 The details of this calculation need not be here oiveu. The 

 little tabulaticm presented herewith gives the diameter, 

 volume and scale of the trees tlien and now. As to scale the 

 same rules were used as earlier. Scaled by the Maine rule, 

 the larger a tree is, the better scale comparatively it gets. 

 Trees eight inches and over at four feet from the ground are 

 considered merchantable. 



Increase per year-cnbic feet, 25; rate at compound interest, 2.1%. 

 Increase per year-feet board measure, 113; rate at compound interest, 2.6%. 



