UTILIZATION OF ASH. 



23 



Rate of growth. — Generally speaking, rapid-growing ash trees pro- 

 duce better timber than slow-growing trees ; the more rapid the growth 

 the greater the density and the better the quality of the timber.^ 

 Nevertheless, j^erfectly thrifty trees grown under widely varying 

 conditions, especially of moisture, will probably show a large differ- 

 ence in rate of growth, with practically no difference in density or 

 mechanical properties. This is known to be true of other species, 

 but data determined are not sufficient to verify it with regard to the 

 ashes. 



Position in tree. — The toughest material appears to be at the butt, 

 and the material strongest as a beam or upright is found higher 

 in the tree. As to position in cross section, the timber of best qual- 

 ity appears to be from 3 to 7 inches from the center of the tree, the 

 quality gradually becoming poorer as the distance from the center 

 increases. Suppressed or slow growth in early life, followed by 

 rapid growth in later life, may upset this relation, and the best 

 material may be found in the outer portion of an old tree. The 

 value of the timber in any portion of the cross section depends on its 

 specific gravity. 



Age. — Since the mechanical powers show a gradual decrease in 

 the wood outside of 7 inches from the center, old trees (or those of 

 large diameter) would average weaker than the younger trees. How- 

 ever, this is by no means an infallible rule. An ash tree of any age 

 which is perfectly healthy and not suppressed is probably putting 

 on v/ood of high mechanical value. Any circumstances causing the 

 vigor of the tree to decrease would probably cause it to put on 

 inferior wood. 



Heart and sap. — The results of tests fail to show that any differ- 

 ence is caused in the mechanical properties by a change from sap 

 to heart. In most mature trees the heartwood is stronger, tougher, 

 and has better shock-resisting ability than the sapwood. On the 

 other hand, in young trees with a very small proportion of heart, 

 the reverse is normally true. The density of the wood is the criterion 

 which indicates which is the better in any particular instance. In 

 trees of equal age and of the same rate of growth but having widely 

 different proportions of sap, those with the larger proportion of 

 sap were not found to be superior to those containing less sap. The 

 data show without doubt that the grading should be on the basis of 

 density and that the percentage of sap should be ignored entirely. 



Locality. — It is probably immaterial in what section of country the 

 timber is grown. The thing to be sought is dense, strong wood. This 

 is best obtained from rapid-growing, comparatively young, small to 



1 Rapid growth, however, is not the reason for better quality, but rather it is the 

 general vigor of the tree which results in density of wood as well as rapidity of 

 growth. 



