186 THE: PRACTICAL PLANTER. 



we frequently find them hollow within, and 

 full of water, which, if not removed, will of 

 a certainty induce the rot. 



When the knot is quite entire on all sides, 

 and perfectly sound, which may be known 

 by striking it with a mallet, it should be suf- 

 fered to remain. But when it is found hol- 

 low as above, it should be sawn clean off, 

 the wound should be smoothed as already 

 directed, cleaned, dried, and laid over with 

 tar, &c. 



SHAKES are a disease in timber for which 

 no cure lies but in the prevention of them. 

 What has been advanced in Section VIII. 

 on pruning the Elm, prevents the necessity 

 of a repetition here. 



THE HURTFUL EFFECTS OF MOSS, IVY, 



&c. growing on trees, must be evident to 

 the most superficial observer. The former 

 is generally occasioned by a stagnation of 

 air, in thick woods, and may be partly re- 

 medied by judicious thinning. But if it pro- 

 ceed from the sickly state of the tree, and if 

 this state proceed from ungenial soil, the best 

 remedy is to remove either the cause, or the 

 plant. Another kind may thrive in its place ; 

 but first improve the soil. 



