Page:Timber and Timber Trees, Native and Foreign.djvu/246

226 even in plank, if exposed to a dry current of air, as under such circumstances it is very liable to split with fine deep shakes from the surface.

Having this serious liability to rend in seasoning, the logs should never be left a week exposed to the influence of drying winds without some kind of protection, for even less than that time is often sufficient to bring about an amount of deterioration which will greatly affect their value. Therefore, to preserve this timber for future use, it should be treated in the same manner as the English common Elm, namely, by immersing it in water; or, if this cannot be done conveniently, it should be cut into planks of thicknesses which would be available for

further conversion if required, taking care to store it in a dry, cool place, under cover, but quite free from draught.

The star-shake, in a mild form, is rather common to this description of timber, but does not usually extend to more than 2 or 3 inches from the pith; there is also another, and rather peculiar defect, consisting of several complete consecutive circles of the annual layers being softer and more spongy than the natural or healthy wood (Fig. 27). They are darker in colour, and contain much moisture, and are, as pointed out in Chapter VI., p. 34, considered detrimental to the quality, strength, and durability, and consequently, to the value of the tree. The surveyor should, therefore, in selecting this wood take only the logs with a uniform whitish colour for his best work, and leave those which are marked with the dark annular layers upon the ends for inferior purposes.

In all other respects the Canada Rock Elm is a safe