Page:Popular Science Monthly Volume 22.djvu/217

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205
ANNUAL GROWTH OF TREES.

of them out. While cutting, I noticed that the concentric rings were very distinct, and it reminded me of M. Charnay's statement. I took sections from the butt-end of each tree (four of them) and dressed the ends off, at an angle of some 35 with the line of the body, thus largely increasing the exposure of each ring, and then counted them.

The situation, exposure, and condition of these four trees were, so far as I could see, identical. I had personal and positive knowledge that they had each twelve years' growth upon them, and I could count on each of the different sections from thirty-five to forty concentric rings. True, I could select twelve more distinct ones between which fainter and narrower, or sub-rings, appeared. Nine of these apparently annual rings on one section were peculiarly distinct, much more so than any of the sub-rings; yet, of the remaining, it was difficult to decide which were annual and which were not.

The thickness of these annual rings varied from two and one half millimetres to twenty-eight. This measure, of course, gave more than double the real thickness; but was preferable to a right-angled measure, as it gave better facilities for exactness, and yet preserved the proportion between the several rings unchanged.

Now, to ascertain what relation or connection there might be between the meteorology of

PSM V22 D217 Annual temperature records affecting tree growth.png