\of Timber y especially Oak, 8c^ ^ 



occurring in their slighter forms, in very severe winters such 

 as that just passed, produce much more notable effects. In 

 this country, as well as in the south of France, many large and 

 hollow trees, especially cork-trees, have been split, and their 

 trunks rent in pieces, by the congelation of water contained 

 within them, and this has taken place with so sudden and so 

 great a force, that the noise produced has been said to have 

 been heard at a considerable distance, resembling the discharge 

 of a musket. 



. A just estimate of these various circumstances will tend to- 

 explain the successive stages of decay, and to elucidate some 

 phenomena apparently paradoxical ; e. ^., that a light soft 

 wood, as cedar, should be more lasting than harder, heavier, 

 and more solid timber, than elm, many kinds of oak and beech; 

 that fir, when exposed to weather, should so rapidly decay, 

 although the resin with which it abounds is insoluble in water; 

 that some woods are almost exempt from the attacks of worms, 

 while others are so peculiarly prone thereto ; and that imma- 

 ture and ill-seasoned timber becomes speedily infested by dry- 

 pot; which, in fact, is the decomposition of the ligneous mate- 

 rial, favoured by heatj moisture, and confined air: in which 

 circumstances, wood, the matter of which is but half elaborated, 

 assimilated, or matured, either from too early, or wrong sea- 

 soned felling, almost inevitably is found to perish. 



Such being the philosophy of decay, the practical application^ 

 of these principles is all that now remains, and it is so obvious 

 that it need not detain us long. To test the probable dura- 

 bility of any untried timber, or any doubtful specimens of a 

 known kind, which was the object mooted at the commence- 

 ment, shall form the conclusion of the present essay ; and the 

 means by which wood may be subjected in rapid succession, 

 and during a short period, to similar or equivalent influences 

 to those which occasion its decomposition when exposed to the 

 atmosphere for ages, are those experiments the results of which 

 have suggested the foregoing observations. 



The strength, elasticity, stiffness, tenacity, toughness, &c., 

 being ascertained in the usual way by taking rods of the wood 

 to be examined, of 2 inches square, and 3 feet long, with 24 

 or 30 inches between the fulcral points, and suspending weights 

 to the centre of each rod, noting in what time, in what degree, 

 iv G2 



