Twigs set upon branches tell a very plain story about the disposition of fibers. Tear a small twig out. by the roots. It has a cone-shaped base. Was it not. very small when it. began, and has it. not added to its diame ter each year inside the trunk as as outside? Take off the bark by peeling it up front below. The sleeve" comes off whole. Less flexible are the wood fibers, but you' will soon see that they form under sleeves. one fur each year. The bark fibers follow the lead of the wood fibers.
If we split a. two-year-old branch through its pith and out into the pith of a. twig, we shall find the fibers below running from main stem to branch. Take a munber of fibers up Wow and they generally tear out into the limb. But (thore the limb there is no such fibrous connection. The fibers go to the angle of limb and trunk and no farther. At, this point the fibers part. to go around the base of the twig. The split through the center has cut them off.
A knot. in a board is a section through the base of sonic limb. If the knot. is set slanting, the limb met the truck at an acute angle. If it makes a right. angle with the board, then the limb grew out horizontally from the trunk. I atu speaking of ordinary lumber.
Let us note again how closely the buds are set upon a twig, and then notice how far apart are the large limbs upon the tree. Those limbs we see are but a few of the many that aspired to grow. If we should saw the trunk into thin sections we could read the record of all these attempts and failures. The close-set. shoots on the sapling stein live a year or two, and then finding that there is not room for them, or that the leaves above east them too much into the shade, many die and drop off. In another year a layer of straight-grained wood covers the place where they were.
But there always remains deep in the heartwood of a great tree a memory of every little branch that started to grow but died in its infancy. Each one is a knot that causes some ripple of the fibers—a little disturbance of the straight grain.
The tree that grows in an open field with plenty of sun and air is branched from top to bottom. Such a tree is hull of knots of all sizes, and its wood makes a poor grade of lumber. But let a tree grow in a crowded forest, and all the little lower branches are whipped off by neighbor trees, or starved for light. Such a tree makes fine timber, free from large knots.
In maple trunks there is a peculiar tendency to preserve any little unevenness of surface, and to magnify the peculiarity by molding subsequent annual layers over the humpy places. Must trees would fill in the hollows, and go on straight. This peculiarity gives us the beautiful cur11 grain occasionally seen in maple. When buds on maple saplings are crowded many are likely to remain dormant, but they live on, hoping there may yet be some chance for them. Other buds may be formed—adventitious them. All may keep on growing inside the trunk though their noses are rarely poked out beyond the bark. Each of these 1)11(15 is the center of a pimple in the wood. When the saw cuts off a slab, the lumber man's shrewd glance detects the valuable bird's-eye maple. There is an eye for each bud. encircled by beautiful wavy rings.
The wood of elm and cypress often gets cross grained, especially near flue base of the trunk.
The fibers will veer to the right for a few years—then swing to the left. The hop hornbeam sometimes winds its fibers spirally about the trunk. Some species of pine exhibit this peculiarity. A distinct waviness is sometimes seen in wood usually straight-grained. Such a condition may be due to the crowding and interlacing of the ends of fibers which lengthen after being formed in the cambium layer. Often a beech tree has its outer layers of wood and bark thrown into wrinkles. Extreme irregularities of grain generally add to the market value of lumber. The beautiful patterns, and the line blending of colors many show when polished, give woods a place in the decorative arts that can be taken by no other material.