320 



THE POPULAR SCIENCE MONTHLY. 



which obtains between the sap wood and the heartwood in this 

 species. 



The ash has certain peculiarities which separate it quickly 

 from the papaw and naost other woods. There is, in short, almost 

 as much individuality in the woody tissues as in the foliage or 

 flowers of many trees. Note, for example, the well-marked porous 



Fig. 0. Radial Section of Pin Oak. 



portions, each ring being made up of two quite distinct parts, 

 namely, the open vascular inner part and the dense fibrous outer 

 portion. This arrangement of substance is conducive to that 

 elasticity so characteristic of the ash, and, together with its medi- 

 um weight, fits it for very wide and extensive service in imple- 

 ments and other ways. 



There is another feature of woods, and one of great value from 

 the artistic as well as economic standpoint, that the solar print 

 illustrates. It is shown in some of its beauty in Figs. 1 and 2, 

 while it fails quite completely in the ash namely, the thin, radiat- 

 ing bands which connect the center of the ste with the periphery 

 and are known to botanists as the medullary rays, and to the 

 workers in wood as the " silver grain." Fig. 4 is here introduced 

 as showing this element of structure in a remarkable manner. 

 The section is of the pin oak, and the lower right-hand corner 

 represents for our purpose the center of the stem. The rings of 

 wood are wide, irregularly scalloped, and show the points of struc- 

 ture previously mentioned in a superior manner. But best of all 

 are the lines shot through the whole timber like rays of light (in 

 the negative. Fig. 5) from the center to the circumference. They 

 introduce another element, which up to this time has been left 



