PROPERTIES OF WOOD. 



High specific weight is opposed to fissibility ; it is more 

 difficult to split heavy, hard woods, than the lighter woods. 

 This applies also to wood from an individual tree, branch wood 

 is less fissile than stem wood, even though the former be straight- 

 grained, but rootwood, though lighter than stem wood, is less 

 fissile, owing to irregularity in its fibres. 



Soundness is a necessary condition for fissibility. Diseased 

 wood is either soft or brittle, according to the nature of the 

 disease ; in either case it is less fissile than sound wood. 

 Owing to the action of the attacking fungi, the wood at length 

 becomes a homogeneous mass, which can no longer be split. 



In judging the fissibility of the wood of standing trees the 

 following favourable factors should be noted : Freedom from 

 branches and knots ; fine bark, with straight fissures. It is 

 stupid and mischievous to cut out a piece of the wood and test 

 its fissibility. 



The following list shows how greatly fissibility depends on 

 species. 



3. St 



The strength of a piece of wood varies with the direction of 

 1,1 1< : Force which tends to alter its shape, so that there are 

 different kinds of strength in wood. 



Tenacity is the resistance a wooden rod offers to a force 

 tending to stretch it. The coefficient of tenacity is the force 

 \\liidi can tear a rod OIK; meter long and one square centimeter in 



