. Check list of the forest trees of the United States : their names and ranges. Forests and forestry; Trees. Fig. 1—A piece of sawn timber cut tbrough along the pith, illustrating its struetunil aggregates. account of the many knots which it invariably and necessarily con- tains—consists in the main of five structural aggregates (see fig. 1), namely: (1) In the center a cone of wood fibers with the base in the butt end and the apex in the top end, the base representing the rings of as many years as it took the tree to attain the height of the column; none of the fibers belonging to these rings
. Check list of the forest trees of the United States : their names and ranges. Forests and forestry; Trees. Fig. 1—A piece of sawn timber cut tbrough along the pith, illustrating its struetunil aggregates. account of the many knots which it invariably and necessarily con- tains—consists in the main of five structural aggregates (see fig. 1), namely: (1) In the center a cone of wood fibers with the base in the butt end and the apex in the top end, the base representing the rings of as many years as it took the tree to attain the height of the column; none of the fibers belonging to these rings appear in the top section excepting those of the last ring wliich forms the a])cx of the cone; (2) a hollow cylinder of material surrounding the cone, all fibers of which are found in both sections and con- tinuously through the whole length of the column; all the entire rings at the bottom belong in this cylinder, and undoubtedly form the strongest part of the column; (3) surrounding this cylinder a jjartial cylindrical envelope of wood fibers, all of which are represented in the top section, but only a part appear at the corners of the bottom; most of them, there fore, do not run through the whole length, but are cut through at vary- ing lengths, thereby presenting the "bastard faces" on the sides of the column; (4) a partial envelope whose radial extent is limited by the corners of the basal section, imperfect at both ends; (5) the corners at the top, three-sided pyramids with the base in the top section, the fibers running out at varying lengths. Now, it will be readily admitted that each of these '' structural aggre- gates" has a different value in the combined strength ot the whole. If the stick be cut with the center or pith in one side (see fig. 2) all these aggregates will be halved; if the stick be cut out differently, for instance, with the heart entirely out or if it be made longer or. g h Fig. 2.—Possibilities of cutting timber from a log -wit
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectforestsandforestry
