14 TIMBER. 



THE ANNUAL OR YEARLY RING. 



The concentric, annual, or yearly rings, which appear on the end 

 face of a log are cross sections of so many thin layers of wood. 

 Each such layer forms an envelope around its inner neighbor, and is 

 in turn covered by the adjoining layer without, so that the whole stem 

 is built up of a series of thin hollow cylinders, or rather cones. A new 

 layer of wood is formed each season, covering the entire stem, as well 

 as all the living branches. The thickness of this layer, or the width 

 of the yearly ring, varies greatly in different trees and also in different 

 parts of the same tree. In a normally grown, thrifty pine log the rings 

 are widest near the pith, growing more and more narrow toward the 

 bark. Thus the central 20 rings in a disk of an old longleaf pine may 

 each be one-eighth to one-sixth inch (3 to 4 mm.) wide, while the 20 

 rings next to the bark may average only one-thirtieth inch (0.7 mm.). 

 In our forest trees rings of one-half inch in width occur only near the 

 center in disks of very thrifty trees of both conifers and hard woods; 

 one-twelfth inch represents good thrifty growth, and the minimum width 

 of about one two-hundredths inch (0.2 mm.) is often seen in stunted 

 spruce and pine. The average width of rings in well-grown old 

 white pine will vary from one-twelfth to one-eighteenth inch, while 

 in the slower growing longleaf pine it may be one twenty-fifth to one- 

 thirtieth of an inch. The same layer of wood is widest near the stump 

 in very thrifty young trees, especially if grown in the open park, but 

 in old forest trees the same year's growth is wider in the upper part of 

 the tree, being narrowest near the stump and often also near the very 

 tip of the stem. Generally the rings are widest near the center, grow- 

 ing narrower towards bark. In logs from stunted trees the order is 

 often reversed, the interior rings being thin and the outer rings widest. 

 Frequently, too, zones or bands of very narrow rings, representing unfa- 

 vorable periods of growth, disturb the general regularity. Few trees, 

 even among pines, furnish a log with truly circular cross section ; usually 

 it is an oval, and at the stump commonly quite an irregular figure. 

 Moreover, even in very regular or circular disks the pith is rarely in 

 the center, and frequently one radius is conspicuously longer than its 

 opposite, the width of some of the rings, if not all, being greater on one 

 side than on the other. This is nearly always so in the limbs, the 

 lower radius exceeding the upper. 



In extreme cases, especially in the limbs, a ring is frequently con- 

 spicuous on one side and almost or entirely lost to view on the other. 

 Where the rings are extremely narrow, the dark portion of ring is 

 often wanting, the color being quite uniform and light. The greater 

 regularity or irregularity of the annual rings has much to do with the 

 technical qualities of the timber. 



