Mil WITHEES- 



wood probably becoming slightly carbonized or ap- 

 proaching to that change which takes place when 

 vegetables become peat. 



It is rather difficult to speak of the strength of tim- 

 ber, as different kinds of timber, and different parts 

 and qualities of the same kind of timber, have diffe- 

 rent kinds of strength. Some kinds are stronger as 

 beams or joists, other kinds as boarding; while, again, 

 some kinds are better for enduring a regular pres- 

 sure, others for supporting a sudden jerk or blow, 

 either as beams or boards. Some kinds are also 

 comparatively stronger, moist ; others when dry — 

 and some kinds retain their qualities of strength or 

 toughness longer than others when moist, and 

 others longer when dry, although no rot appear. 



No. 7. Purposely for experiment*, we selected three 

 ash trees, all growing in Carse clay, but differing the 

 most in fastness of growth of any we could discover. 

 We cut these down on the same day ; two of them 

 proved about 36 years planted, and the third 1 5 ; 

 this, the youngest was of fast growth, and had 

 layers of more than double the size of one of the 



• Though we give this experiment, we admit that little de- 

 pendence can be placed upon a single fact. The trees must have 

 been different in variety, and probably in sexj, both of which may 

 occasion a discrepancy, 



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