When the trunk of a tree is sawed through, we can see that there are
many rings, starting at the center, and growing outward in distinct
circles to the outer bark. These rings are called "annual rings,"
because "annual" means "yearly" and usually one ring is formed for every
year of the tree's life.
When the trunk of a tree is sawed through, we can see that there are many rings, starting at the center, and growing outward in distinct circles to the outer bark. These rings are called "annual rings," because "annual" means "yearly" and usually one ring is formed for every year of the tree's life.
By counting these rings we can tell how old the tree was, and by examining the width and regularity of separate rings, we can tell what has happened to the tree at any time—when it was sick, and when conditions of water and climate were good or bad. If insects ate up the leaves one year, or if there was a drought, two rings might be formed in one season. These are called "false rings," and it is easy for scientists to tell them from the others. One important use of annual rings is in furniture manufacturing and carpentry. Wood, as it dries, "moves," or warps, in a direction away from the small rings, or center; so by looking at the rings, the carpenter knows better how to glue, or fasten, the pieces of wood together.
