FOREST COMMISSIONER'S REPORT. 91 



millimeters. The same dEi,ta are obtainable for the upper sections, 

 and the yearly growth of the tree at that period can be ascertained 

 as before. The data are as follows : 



]j =13.7 feet. di=8 inches, yj =8111111. 

 1, = 18.3 " d,=5.1 " 7^=7 " 



l3 = 15.S " cl3=4 " ys='' " 



The problem works out with 18 cubic feet as an answer. 



Now this tree 70 years ago at 4 feet from the ground was about 

 11 or 12 inches in diameter. The volume of its growth at that 

 time therefore will stand as well as that of another tree as repre- 

 sentative of the 10-14 inch class on that site The same tree 

 stripped to about 8 inch diameter at 4 feet showed an annual 

 growth of about 1 cubic foot. These results and similar ones are 

 utilized in ascertaininsy the growth upon acres at sites c and q. 

 They would not be reliable unless logs were cut very short, and at 

 those points a few were so cut in order to obtain material to be 

 used in straight tests of timber * 



Numerous questions have come up in the course of the foregoing 

 work, and their pursuit has brought out several interesting and val- 

 uable facts, facts however not new to forestry science. 



First I will note that the ring of the year's, or ten year's growth 

 is thicker high up in the trunk of a tree than it is nearer the ground. 

 There are exceptions to the rule, and slight irregularities make 

 numerous apparent ones. But the schedules herewith presented 

 will bear me out, while the principle has been proved from much 

 wider evidence. A corollary of wide application is that as long 

 as a tree is growing, its trunk is decreasing in tapir or becoming 

 more cylindrical. From this we learn that in reckoning the value 

 of growth the added volume is not the only consideration. That 

 volume is placed to best advantage, while in other respects the tim- 

 ber may be improved in quality In the region of the crown the 

 rule will not hold as formulated. There is great variation in the 

 matter ; but according to the evidence at my command, in a major- 

 ity of trees, the principle does hold there. 



Then in reckoning the volume of growth the question arose — is 

 the greater thickness of the rings as we go up the tree sufficient to 

 effect the taper of the trunk, and give to the upper ring as great an 

 area as the lower one? From the nature of the subject and 



*For purposes and methods of this investigation see Bulletin No. 6 of U. S. For- 

 estry Division— title Timber Physics. 



