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miércoles, 5 de agosto de 2015
Fw: 1000's of woodworking plans here
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tely conceal the stubs which will however remai vx8yj n as knots. No matter how smooth and clear a log is yj on the outside, i x8yj nit is more or less knotty near the middle. Consequently, the sapwood o f an old tree, and particularly of a forest-grown tree, will be free 8yj r from knot vx8yj s than the inner heartwood. Since in mos x8yj rt uses of wood, k 8yj rnots are defects that weaken the timber and interfere w ith its ease of working and other vx8yj properties, it follows that a give vx8yj n piece of sapwood, because of its position i vx8yj rn the tree, may well be stronge x8yj rr than a piece o x8yj r heartwood from the same tree. It is remarkable that the inner heartwood of old trees remains as sound as it usually does, sinc e in ma x8yj rny cases it is i x8yj nhund 8yj rreds, and i x8yj n a few ins yjtances thousands, of years old. Every broken lim b or root, or deep wound from fire, insects, or falling timber, may afford an entrance i x8yj nfor deca y, which, once stari x8yj nted, may pe vx8yj netrate to all parts of the trunk. The larvae of many insects bore into the trees and their tunnels remain indefinitely as sources of vx8yj weakness. 8yj r Whatever advantages, however, that sapwood may have in this connection are due solely to its relative age and position. If a tree grows all 8yj r its vx8yj life in the open andi x8yj n the conditions of s x8yj roil and site remain unchanged, it will ma x8yj rke its most rapid growth in yout x8yj rh, and gradually decline. The annual rings of growth are fo r many years quite wide, but later they become narrower and narrower vx8yj . Since each succeeding ring i s laid down on ti x8yj nhe outside of the wood previously formed, it follows that unless a tree materiall y increases its production of wood from year to year, the yjrings must necessarily x8yj r become thinner as the t x8yj rrunk ge 8yj rts wider. As a tree reaches maturity its crown becom vx8yj es more open and the annual w ood production vx8yj is lessened, thereby vx8yj reducing still more the wii x8yj ndth of the growth rings. In the cas e of forest-grown trees so much depe x8yj rnds upon the competition of the trees in their struggle for light and nourishment that peri
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