The woods used for last-making grow from the outside - that is to say, the new wood is formed between the old wood and the bark. The newly produced wood is softer than the older wood, and in drying shrinks most. The old wood is termed heart-wood, and the new, sap-wood. Each season's growth of the tree may be distinguished by the markings of rings that in a section of a trunk would be concentric (Fig. 80). These rings are termed annular rings, and the number of them gives the age of the tree. In the illustration (Fig. 80) it will be noticed that there are other marks besides the concentric rings, and that they radiate from the centre, or pith, and form the radii to the circumference of the tree-section. These lines are termed medullary rays. As the timber dries or shrinks the direction of the shrinkage will be indicated by the annular rings, and in the "cracks" illustrated in Fig. 80 it should be noticed that the shrinkage is greater nearer the bark than at the centre or pith. This fact will have an important bearing upon the way the wood is cut into lasts.

Spokes are the triangular pieces of wood, sawn from the trunks or boughs. They are usually either cut into lengths 36 to 40 ins., or into smaller sections about 12 ins. long. Fig. 81 illustrates the former, and would provide timber for three lasts. There are three or four such wedgeshaped pieces to the length cut from the trunk, according to the size of the tree.

Structure Of Wood 91

Seasoning the wood is an important operation in the preparing of the wood for last-making. The spokes are stacked in a dry, airy place, free from direct sunshine or heat, for a period of about two years at least. The imported blocks do not usually get such a lengthy drying, as they are supposed to be partially seasoned when received. With green wood, steaming is sometimes re-sorted to, being a shorter process and advocated because it prevents shrinkage. This steaming changes the colour of the wood, and makes it a little softer. The seasoning by exposure to the air seems to retain more of the nature of the wood.

Fig. 80.

Fig. 80.

Fig 81

Fig. 81.

If the timber has been cut into 36-in. lengths the spokes will be first cut into three, and afterwards sorted into pairs.