442 Scientific Intelligence. 
of the trunk at the place whence it was taken is about 5 feet 2 inches. 
If the tree increased in diameter at the same rate throughout, there 
would have been 2976 annual layers; which, allowing 24 years for the 
tree to have egress: ihe height of 25 feet, would give it an age of 300 
years froin the seed. ‘This mre so closely with Dr. Lindley’s 
estimate that we pa suppose him to have employed equivalent data in 
a similar manner. How great a deduction must we make from this es- 
timate, in consideration of the greater thickness of the layers as a 
younger tree? ‘The only direct data 1 possess bearing on this — 
are derived from a piece of a transverse section 3$ inches deep, o 
“rail,” which the exhibitor says was taken from the trunk at the height 
of 275 feet from the ground. As its layers, on a breadth of nearly 
gths of an inch, show only a slight curvature, it must have come from 
a part of the trunk still of several feet in diameter. On this settion the 
exterior inch, nearly all alburnom, contains 90 Jayers ; the next 60; the 
next 45, the remaining half inch 16, making 32 to the inch. That the 
exterior layers shou ld. be thinner at this height than those near the base 
ree, is just what wouid be expected. If we apply this ratio of 
decrease of the number of layers to the inch as we proceed inwards, 
within that part of the anoalibcce which ] have examined, have — 
only 17 layers to the inch, which taken as the average thickness, would 
make the tree only 1034+4-24— 1058 years old. But it is not probable 
that the thickness of the layers increases so rapidly. | The data we pos- 
sess on other trees goes to show that a tree after it is 400 or 500 years 
old, increases in diameter at a pretty uniform rate for each 20 additional 
years, on the whole, although the difference in the thickness of any 
of an old one, ett ee! we Witla not be warrauted in assuming more 
than the average of 17 layers to the inch for the whole sectio 
Some useful data m may be obtained from a tree more eit related 
in semi-dia 
it to — roe at the intermediate ratio of 35 layers per 
the nex —— and at the actual rate of the last rentury ts ascer- 
tained by inspection), namely at 48 layers per inch, for | yy ee 
10 inches, we on ae assign to it the age of 2066 years. as it 
