|
Wednesday, August 5, 2015
1000's of woodworking plans here
| Click Here ToUnsubscribe  |
tely conceal the stubs which will however remai 8zti1 n as knots. No matter how smooth and clear a log is i1 on the outside, i zti1 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 ti1 r from knot 8zti1 s than the inner heartwood. Since in mos zti1 rt uses of wood, k ti1 rnots are defects that weaken the timber and interfere w ith its ease of working and other 8zti1 properties, it follows that a give 8zti1 n piece of sapwood, because of its position i 8zti1 rn the tree, may well be stronge zti1 rr than a piece o zti1 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 zti1 rny cases it is i zti1 nhund ti1 rreds, and i zti1 n a few ins i1tances thousands, of years old. Every broken lim b or root, or deep wound from fire, insects, or falling timber, may afford an entrance i zti1 nfor deca y, which, once stari zti1 nted, may pe 8zti1 netrate to all parts of the trunk. The larvae of many insects bore into the trees and their tunnels remain indefinitely as sources of 8zti1 weakness. ti1 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 ti1 r its 8zti1 life in the open andi zti1 n the conditions of s zti1 roil and site remain unchanged, it will ma zti1 rke its most rapid growth in yout zti1 rh, and gradually decline. The annual rings of growth are fo r many years quite wide, but later they become narrower and narrower 8zti1 . Since each succeeding ring i s laid down on ti zti1 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 i1rings must necessarily zti1 r become thinner as the t zti1 rrunk ge ti1 rts wider. As a tree reaches maturity its crown becom 8zti1 es more open and the annual w ood production 8zti1 is lessened, thereby 8zti1 reducing still more the wii zti1 ndth of the growth rings. In the cas e of forest-grown trees so much depe zti1 rnds upon the competition of the trees in their struggle for light and nourishment that peri
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment