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NOTICES OF AUTHOES. 



not lie in the bark after felling, and the boards must 

 be well di'ied soon after being cut out. To expose 

 the tree, peeled, either standing or felled, to the sun 

 and dry air for some time, vnll considerably increase 

 the strength of this alburnum. The wood, while in 

 the state of sap-wood, of many kinds of timber is as 

 strong and much tougher than the same wood after 

 being matui'ed, and would be equally valuable were 

 any process discovered of rendering it equally dura- 

 ble ; its insufficiency often arises from partial decay 

 having occurred while in the log. The same sap- 

 wood of oak, which, allowed to lie on the grass after 

 being peeled in spring, will be so much decomposed in 

 autumn that it may be kicked off with one's heel ; 

 if cut out and dried immediately on being felled, it 

 will be tougher than the matured, and, kept dry as 

 cart-spokes, and defended by paint from the worm, 

 will last and retain its toughness for an age. The 

 tilling up, which to a certain extent occm's in ma- 

 tui'ing, is most probably deposited to fill up tubes, 

 and may thus not greatly strengthen the mass ; 

 a hollow cylinder being stronger than a solid cylin- 

 der when extending horizontally over a considerable 

 stretch, like a joist or beam ; the mass may also be- 

 come a little more fragile by matming : besides a fill- 

 ing up is the result of some chemical change the 



