128 



TIMBER. 



change in the timber (easily recognisable by the 

 sense of smelling when any section of it is made), 

 which, judging from the effect the acetous change has 

 to preserve other vegetable matter from putrefaction, 

 is probably of considerable use in preserving the 

 timber from decay, either by rot or worming. The 

 time of cutting, although of considerable importance 

 to the quality and durability of the sap-wood, ap- 

 pears to be of little or none to the matured. 



The age at which timber may be cut down 

 being uncertain, the height to which it should be 

 trained up of clear stem is not very determinable, — 

 say that the trees are to be allowed to stand till 

 nearly full grown, — as long as the timber continues to 

 retain its strength and toughness when growing in 

 proper soil, that is for hard-wood trees 100 years 

 and upwards, and for pines from two to three hun- 

 dred. On crowns of eminences and exposed bluffs, 

 particularly when the latitude or altitude is rather 

 high, the soil inferior, or the climate arid, from 15 

 to 30 feet of clear bole may be as much as can judi- 

 ciously be attempted ; upon plains under common 

 circumstances, from 30 to 50 feet is an attainable 

 stem ; in sheltered dales and valleys, they may be 

 trained clean, and without branch, from 50 to 70 

 feet in altitude ; and in cases where soil, situation, 



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