66 



TIMBER AND TIMBER TREES. 



[CHAP. 



producing there what is technically termed a " druxy 

 knot." This defect, if prevented from spreading by the 

 otherwise healthy and vigorous state of the tree during 

 its growth, must still be looked to after 

 it is felled, since, if neglected, there being 

 no longer any check to its development, 

 ^~X^f fresh moisture will be absorbed, decay 



*^' -'^^ will be accelerated, and the whole log 

 soon destroyed. To guard against this, 

 it would be proper, as soon as the log is 

 appropriated for any purpose, to take 

 out and completely remove the affected 

 part, substituting in its place a piece of 

 sound wood. 



Again, the damage done by the 

 breaking of a branch from a tree is often 

 very serious, as illustrated in Fig. 13, 

 The wound was of very old standing, 

 and entirely healed over, but the decay 

 had nevertheless made steady progress. 

 It was found, by counting the concentric 

 layers, that the branch was broken when 

 the tree was fifty-six years old ; that in 

 twenty-three years more the annual 

 layers had completely covered the 

 broken part, while outside this twenty- 

 third layer there were twenty -seven 

 years' growth of duramen or heart-wood, 

 and twenty-six years' growth of albur- 

 num or sap-wood, the tree having been about 132 years 

 old at the time of its being felled. 



Pruning closely, except in the case of very young 

 trees, where the branches are small, and the wound is 

 certain to be soon healed over, will, as before shown 



FIG. 14. 



