Thus, if you began at the outer layer of the two trees, one young and the other old, and counted back 20 years, if the young tree indicated, by a full layer, a growing season for that kind of timber, the other tree indicated the same. Such a comparison would elicit a mass of fact, both with respect to the progress of the seasons, and their relation to the growth of timber, and might prove, hereafter, the means of carrying back our knowledge of the seasons, through a period coeval with the age of the oldest forest trees, and in regions of the country where scientific observation has never yet penetrated, nor a civilized population dwelt. Jacob Kuechler-Texas 1859. Keuchler sets up a deliberate experiment. A tree contains the record of its life history, and this history is most closely interwoven with the annual rainfall.
Water is the principal factor in the growth of a plant, for without water growth is impossible.
Annual growth is shown by the tree-ring, the width of which depends on the available water. Thus, broad rings indicate wet years, and narrow rings-sometimes so small they can barely be seen with the naked eye, indicate dry years. . Great care must be exercised in the selection of trees for experiment, for one can be led astray by trees which have been subject to abnormal conditions. I cut down three post oak trees, two of which were a little over one hundred years old, the third being one hundred and thirty years old. At the thick end I cut a section from each tree, planed its surface very smooth, and then varnished it, which made the rings plainly visible.