. Wood and forest . which they are subjected, andwarping, or uneven shrinkage. In order to neutralize warping as much as possible in broad boardstructures, it is common to joint the board with the annual rings ofeach alternate board curving in opposite directions, as shown inHandworh in Wood, Fig. 280, a, p. 188. Under warping is includedbowing. Bowing, that is, bend-ing in the form of a bi3w, is,so to speak, longitudinal warp-ing. It is largely due tocrookedness or ij-regularity ofgrain, and is likely to occur inboards with large pith rays, asoak and sycamore. But evena straight-grained piece
. Wood and forest . which they are subjected, andwarping, or uneven shrinkage. In order to neutralize warping as much as possible in broad boardstructures, it is common to joint the board with the annual rings ofeach alternate board curving in opposite directions, as shown inHandworh in Wood, Fig. 280, a, p. 188. Under warping is includedbowing. Bowing, that is, bend-ing in the form of a bi3w, is,so to speak, longitudinal warp-ing. It is largely due tocrookedness or ij-regularity ofgrain, and is likely to occur inboards with large pith rays, asoak and sycamore. But evena straight-grained piece ofwood, left standing on end oi-subjected to heat on one sideand dampness on the other, willbow, as, for instance a boardlying on the damp ground andin the sun. Splitting takes variousnames, according to its form in the tree. Check is a term used for all sorts of cracks, and moreparticularly for a longitudinal crack in timber. Shakes are splitsof various forms as: star sliahes, Eig. 41, a, splits which radiate from. Fig-. 41. a, star Shakes; *, Heart Shakes; c. Cup Shakes or King- Shakes; d, Honey- combingr. 48 \MJOD AND FOREST. the ijith along the pith rays and widen outward; lirari sluihes. , h, splits crossing the cential rings and widening toward the cen-ter; and cup or ruuj .shakes. Fig. 41, c, splits between the annualrings. Honetjcomhing, Fig. 41, (/, is splitting along the pitli raysand is due largely to case hardening. These are not all due to shrinkage in drying, but may occur inthe growing tree from various harmful causes. See p. 232. Wood that has once been dried may again be swelled to nearly ifnot fully its original size, l)y being soaked in water or subjected towet steam. This fact is taken advantage of in wetting woodenwedges to split some kinds of soft stone. The processes of shrinkingand swelling can be repeated indefinitely, and no temperature shortof burning, completely prevents wood from shrinking and swelling. Eajiid drying of wood tends to case har
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectforests, bookyear1912
