Excerpt from Framing, Sheathing, and InsulationThe series of concentric rings sur rounding the pith are formed by the growth of the tree, one ring being added on the out side each year, hence the name, annual rings. These annual rings, as shown in the enlarged section, Fig. 1 - 2, are composed of fibers or long tubes running parallel to the trunk of the tree. The annual rings are crossed by fibers or cells that run from the bark of the tree to its center, conveying nourishment from the outer cambium layer to the inner part of the tree. These cells are called medullary rays.About the PublisherForgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.comThis book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully, any imperfections that remain are intentionally left to preserve the state of such historical works.