. The elements of forestry, designed to afford information concerning the planting and care of forest trees for ornament or profit and giving suggestions upon the creation and care of woodlands with the view of securing the greatest benefit for the longest time, particularly adapted to the wants and conditions of the United States. Forests and forestry. The Gaining Bates of Tree-Growth. 81. t xttt m under careful management, and very considerable at the end of the appointed periods. 288. To illustrate the rates of this increase, we will suppose that the annual rings of growth in a tree arc of
. The elements of forestry, designed to afford information concerning the planting and care of forest trees for ornament or profit and giving suggestions upon the creation and care of woodlands with the view of securing the greatest benefit for the longest time, particularly adapted to the wants and conditions of the United States. Forests and forestry. The Gaining Bates of Tree-Growth. 81. t xttt m under careful management, and very considerable at the end of the appointed periods. 288. To illustrate the rates of this increase, we will suppose that the annual rings of growth in a tree arc of equal width. As a matter of fact, they are much wider in some years than in others, but, for il- lustration, we will consider them as uniform in thickness. Counting from the center outward, we would have the numbers 1, 2, 3, 4, 5, etc., showing the years of growth. The areas of these circles (each including those within it) are 66. concentric Rings of as the squares of these numbers, viz., 1, 4, 9, 'ireu Growth. 16, 25, etc. By subtracting each of these from the preceding, we have the series, 3, 5, 7, 9, etc., that represents the gain of each year upon the year jyrecedlng. 289. These relative rates may be shown by a simple diagram, in which the gain in diameter is represented by the lower diagonal, and the gain in area by the ujiper one. The numbers alon"^ the bottom in this fiL^'ure represent the years, and those on the margin units of quantity. The rates thus shown are actually maintained for many years, while young, but be- come less as the trees approach maturity. They show the waste from cutting thrifty young timber at the period of most profitable growth, and should lead us to spare it, when possible, till it has^' gained its full value. 290. But these gaining rates are only those of sectional area ; the trees are at the same time gaining in height, and the timber is gain- ing in quality and value j)er cuhic foot, as it grows older, for it can then be applied to more
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