es OF WOOD IN GENERAL 



bark and sapwood of the Teak three years before it is intended to 

 fell it. This stoppage of all ascending sap kills the tree in a few 

 weeks : the heat of the climate helps the seasoning process ; and, 

 as usually about a year elapses between the felHng of the timber 

 and its delivery in England, it is then fit for immediate use. It is 

 recommended that the dense Australian timbers should, hke Teak, 

 be ringed while standing. This should be done a year or more 

 before felling, and between April and August, when the sap is 

 quiescent. The tree is most thoroughly drained of its sap when 

 thus left vertical. It has, however, been objected to this process 

 that it causes or intensifies heart-shake, and, by drying the wood 

 too rapidly, renders it brittle and inelastic. 



Seasoning of some kind is, in all other cases, rendered imperative 

 by the changes in volume, irregular shrinkage, or warping, that all 

 green woods undergo under the influence of changes in atmospheric 

 temperature and moisture, especially in their cross sections. So 

 important is it to avoid this warping in furniture, wheelwright's 



Fia. 42.— Plank iDadly laid, witli the mside, or inner rmgs, upward. (After Laslett ) 



work, etc., that it is a common practice to block out work roughly 

 and let it season a little longer before finishing. 



Seasoning is ordinarily understood to mean drying; but, in 

 addition to the evaporation of water, it impHes other changes, such 

 as the drying out or partial decomposition of the albuminous sub- 

 stances in the wood, rendering it more permeable and less ferment- 

 able. 



The strength of many woods is nearly doubled by seasoning, 

 hence it is very thriftless to use it in a green state ; as it is then not 

 only weaker, but is liable to continual change of bulk and form. 

 The longitudinal fibres of the wood being, as it were, bound together 

 by the radiating pith-rays, as the wood shrinks it finds reHef by 

 splitting radially from the centre along the pith-rays. When a log 

 is sawn into four quarters, by passing the saw twice through the 

 centre at right angles, the outer annual rings shrink the most, so 

 that the two flat surfaces of each quarter of the log cease to be 

 strictly at right angles to one another. In tangent-sawn timber, 



