. 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. Defects of Timber. 143 If, on the contrary, a plank be laid flatwise, with the hollow of the grain up, the pressure of whatever weight is applied, will be on the inside of the arch, and if exposed to moisture, the water will tend to settle bet
. 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. Defects of Timber. 143 If, on the contrary, a plank be laid flatwise, with the hollow of the grain up, the pressure of whatever weight is applied, will be on the inside of the arch, and if exposed to moisture, the water will tend to settle between the layers of growth, and thus hasten its decay. These principles find application in the laying of planks in side- walks, bridges, platforms, the floors of warehouses, and the Defects of Timber from Various Causes. 578. Timber is liable to acquire certain defects from shrinkage in seasoning, or other causes, that more or less injure its quality for strength, and its value for use, when sawn into lumber. One of these is the " heart-shake," perhaps most frequently seen in old timber, and caused by the contraction of the inner portions of the tree, as the first symptom of decay. 579. The "star-shake" consists of a similar contraction, but often wider to- wards the outside, as. seen in young tim- ber when exposed to rapid drying after being cut green. It, however, is often seen in the tree before cutting, and some- times a bulge on the outside of the tree shows where these cracks come to the surface. 580. The "cup-shake" is a separation between the rings of growth, more fre- quently found near the roots of the tree. It may be caused by a sudden change of temperature, frosts, storms, or other causes, and in some cases it extends through the whole length of the tree, es- pecially if the ring of separation is com- plete at the base. If only a segment is separate, it does not usually extend far up. Again, there are various combina- tions of th
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectforestsandforestry
