vi.] EXCRESCENCES. 35 



character, but are nevertheless the early or first stage of 

 incipient decay, and will be found less able to resist the 

 action of water than the wood of the same log which 

 is untainted. Although these spots can hardly be 

 reckoned as defects, seeing that they do not penetrate 

 deeply enough to affect in any appreciable degree the 

 value of the timber, the surveyor would do well not to 

 employ such logs in architectural works where it would 

 be difficult to replace the piece should it at any time be 

 found to be decayed. 



A swelling upon the exterior of a tree is generally a 

 sign of some defect being hidden beneath ; it may be 

 confined to the alburnum, but it may also conceal a 

 serious fault that would be highly detrimental to its 

 value. 



The excrescence should, therefore, be removed as soon 

 as the tree is felled, in order to clear up the existing 

 doubt. There are, however, some few exceptions to 

 this ; for instance, the burrs which are found upon the 

 Oaks of some districts,* and the Austrian and Turkey 

 Walnut tree burrs, which are very finely mottled and 

 figured, make good veneers, and have of themselves a 

 special value for cabinet purposes. 



The removal of a branch of moderate size from a 

 tree, close down upon the stem, will generally be con- 

 cealed by a swelling of the kind first mentioned, 

 particularly if it has been done while the tree was in 

 a healthy state and annually forming new wood. Such 

 hidden knots are frequently in a state of incipient 



* These peculiar excrescences are supposed to be caused by punctura- 

 tions of the bark by insects, while the tree is growing ; but, so far as I am 

 aware, the quality of the trunk of the tree is not often affected by it. Vide 

 Description of the Walnut Tree, page in. 



