36 TECHNICAL PROPERTIES OF WOOD. 



constantly on an unsymmetrical crown, that it is often peculiar to 

 certain localities, every tree therein being affected (e.g., the Pinus 

 longifolia forest at Ranikhet just below the road to Almora), and 

 that stunted trees and those growing out in the open are much 

 •oftener twisted than tall trees or those standing in the midst of a 

 leaf-canopy. Teak seldom if ever suffers from this defect. Twist- 

 ed fibre renders wood useless for a great many purposes : it reduces 

 the strength of sawn timber in proportion to the smallness of the 

 scantling, it renders the wood liable to warp and split very badly, 

 and it prevents any kind of effective planing. Wood with twisted 

 fibre has, however, greater transverse strength thau straight- 

 grained wood if used as large beams. 



4. Rind ff alls. 



These are local wounds that have healed up and been covered 

 over with new layers of wood. The wounds are such as may be 



Fig. 5. 



Jtitidffull. 



caused by a falling tree, a passing cart, an animal rubbing its 

 horns, &c., or by the bark being killed by fire or hot blasts of wind. 

 There is always a break of continuity in the first few rings formed 

 after the accident, and, however quickly the wound may heal over 

 there is never any union between the new covering rings of wood 

 and the surface exposed by the wound, and some amount of decay 

 is always present. The portion affected by a rindgall must be cut 

 out of all planks and small sawn stuff, also from cask staves ; and 

 if decay has made any appreciable progress, which is nearly always 

 the case, the entire affected portion must be removed, whatever 

 use the log may be put to. 



