Page:Timber and Timber Trees, Native and Foreign.djvu/34

14 tapering or conical form (Fig. 6), and elongating themselves year by year, so that a large proportion of those visible at the butt are traceable at the upper part of the stem. A given diameter of wood consequently contains many more layers at the top than at the butt end of the tree.

The following table is given to show the number of concentric rings counted in the butt and top ends of four very fine English Elm trees:—

From the examples here given, we find that about 84 per cent, of the layers seen at the butt were traceable at the part where the tree was topped off. We also see by the number of layers in one inch of wood at the top, as compared with the butt end, the approximate taper of the cones just referred to.

It is very generally admitted that, in latitudes having the seasons clearly defined as they are in this country, each circle of lignine is completed in one year, but opinions differ as to this being the case in tropical climates, and there are botanists who consider that as