of TimheTt especially OaJe, Sfc, 6l 



example, take the oak, so far from living on the principal, as does 

 the spendthrift poplar, although some change takes place in 

 the heart-wood for many years, the cells are not left void, but 

 more and more substance is deposited in these ligneous recep- 

 tacles, by which the alburnum becomes converted into dura- 

 men, and the duramen becomes gradually matured ; for, 

 although vegetable anatomists in general distinguish only two 

 kinds of wood, the sap and the heart, or spine, in large trees 

 there are many gradations of each ; and although the vital func- 

 tions are more energetic in the one, the other is not devoid of 

 activity, and ought not to be considered dead. When life is 

 totally extinct in the centre of a tree, chemical changes, more 

 or less rapidly, ensue ; the duramen is unable to resist external 

 influences, and it absorbs extraneous and often hurtful sub- 

 stances, which the living parts eschew. You may remember 

 shewing me a specimen of a beech-tree, some of the heart- 

 wood of which was dead, and which had become stained by 

 water draining through forge ashes, that had been cast in a 

 heap near its trunk, but the alburnum and the outer hve rings 

 of the duramen had resisted that external impression, to 

 which the whole were equally exposed, but which the lifeless 

 portion had no power to avoid. 



Much too little stress has hitherto been laid upon the pre- 

 mature cutting of timber ; we hear, indeed, the practice repro- 

 bated, of falling fourscore young oaks, when their aggregate 

 contents were considerably less than what is often found in a 

 single tree ; but there, the objection seems rather to have been 

 made to the quantity than the quality of the wood. As great 

 an error occasionally, though not so frequently, occurs, of 

 allowing trees, designed for timber, to stand too long. This has 

 also been, and very properly, objected to ; but here the objec- 

 tion has been made to the chances of injury that the tree 

 may get, the diminution of timber by the loss of limbs, or the 

 hollowing of the trunk : but, besides these, another most im- 

 portant objection would seem to me to consist in allowing the 

 heart-wood to become too far indurated, by which that balance 

 of qualities, which constitute the great superiority of good 

 English oak, is considerably interfered with, and if any decay 

 occur, the durability must also be correspondingly impaired. 



Ordinary decay in timber, and, indeed, in most vegetable 



JAN. — MARCH, 1830. G 



