CHAPTER XI. 



EUROPEAN TIMBERS — (Continued). 



ON THE FELLING OF OAK IN SPRING AND WINTER. 



The bark of the Oak tree, or, more strictly speaking, 

 the cortical tissues under the true bark, contains a sub- 

 stance called tannin, which is of considerable value, and 

 is used in the preparation of leather. Therefore, in 

 order to secure this tannin in its greatest quantity, it is 

 the practice to fell, or cut down, the trees in the spring 

 of the year, when the sap is rising ; moreover, the bark 

 is more easily removed in the spring. Under other 

 circumstances, the trees would have been cut in the 

 winter, while the sap was down and in a quiescent state 

 — a period which has been almost universally recognised 

 as the best for felling, as it ensures a better quality, and 

 is conducive to the greater durability of the timber. This 

 is because the walls of the wood-elements are then 

 thoroughly lignified and hardened, there is less water in 

 the wood, and the decomposable substances are less abun- 

 dant and less in a soluble form conducive to rot. The value 

 of the bark, however, generally overrides this considera- 

 tion, since, although the weight in proportion to the con- 

 tents of the timber will vary according to circumstances of 

 growth, it is always thought profitable to save it, and. 



