64 TIMBER AND TIMBER TREES. [CHAP. 



end of the log. These are not often of a very serious 

 character, but are nevertheless the early or first stage of 

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

 action of water, or oxidation and destruction consequent 

 on alternate drying and wetting, than the wood of the 

 same log which is untainted. Although these spots 

 can hardly be reckoned as hopeless 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 exist- 

 ing 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 



* These peculiar excrescences ai-e 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. 



