FELLING. 313 



so as to induce early decay, the sooner it is hewn off 

 the better. While the bark on any fallen tree remains 

 sound, it defends the wood from being- cracked by the 

 sun and air ; but it should not remain after it is rotten, 

 because it forms a harbour for many insects which 

 prey on the wood. 



Fir and pine timber may be, as before observed, 

 felled at any season ; because the sap being gross and 

 resinous, is less fugitive than that of deciduous trees. 

 It is also to be remarked of pine-trees, that whereas 

 deciduous kinds become decomposed first at the pith, 

 pines are first decayed on the exterior, owing, no 

 doubt, to the internal store of preservative juice. 



The quality of timber of every kind of tree is 

 always found to be in the greatest perfection when 

 grown on land which is naturally most suitable to 

 them. The most valuable properties uf timber are 

 solidity, ponderosity, toughness, and durability. Ra- 

 pidity of growth gives a coarser grain, and also greater 

 strength of fibre. An oak raised on a sandy or moor- 

 earthy soil, yields timber of a milder texture or grain, 

 than that from off loamy clay ; but it is also less 

 tough, and probably less durable. The durability of 

 oak depends on the strength of the fibrous structure 

 forming the vascular parts of the wood. The fir 

 shows that its cellular members, namely, the exterior 

 side of each year's growth, resist decomposition for 

 a longer period than the intermediate portions of the 

 wood. We have only to look down on an old deal 

 floor to be convinced of this fact, and to an old oak 



