THE WOOD AND ITS MECHANICAL PROPERTIES. 55 



In this connection, attention may be called to the low value of 

 green, eastern shagbark, as shown in Table 18 and figure 17, as com- 

 pared to that of Ohio and Mississippi. This is hard to explain, but 

 corroborates the prejudice which some eastern users have against 

 shagbark. Dry specimens do not show this inferiority. 



A more thorough study will be necessary before definite conclusions 

 can be drawn. 



It is clear, therefore, that the difference in northern and southern 

 hickory is not due to geographic location, but rather to the character 

 of timber that is being cut. Nearly all of that from southern river 

 bottoms and from the Cumberland Mountains is from large, old- 

 growth trees; that from the north is from younger trees which are 

 grown under more favorable conditions, and it is due simply to the 

 greater age of the southern trees that hickory from that region is 

 lighter and more brash than that from the north. 



SPECIES. 



According to Tables 15 and 18 and figure 17, pignut, which is gen- 

 erally considered best, is actually the strongest and toughest and is 

 comparatively uniform for all regions. Shagbark is only slightly 

 inferior to pignut; big shellbark is of only medium strength, but 

 is inferior to no other species in toughness; mockernut is somewhat 

 stronger than big shellbark, but lacks toughness. 



The pecan hickories are very little used throughout the region 

 where hickory is ut, and spoke and handle makers consider them 

 inferior; the few tests which were made suffice at least to show that 

 this prejudice is well founded. JBitternut from northern Ohio, which 

 was of the best quality of second growth, is slightly inferior to other 

 hickories from the same region. Nutmeg and water hickories are 

 characteristically shaky, and the tests show that the wood is inferior 

 to that of the true hickories. 



Strength and toughness vary greatly within the same species. 

 Thus, although pignut from Pennsylvania is very strong and tough, 

 it will yield much material which is no better than the average of the 

 pool- species grown is less favorable localities. In general, the lowest 

 grades of the best of the true hickories are no better than the average 

 of the poorest pecan hickories. While, therefore, the different species 

 have different average values and this is an important consideration 

 in forest management and in the buying of trees in the woods the 

 selection of the best hickory in the yard can not be based on anything 

 but a most rigid inspection and grading. The pecan hickories all 

 produce inferior timber, and true pecans, if grown for the commercial 

 value of their fruits, should not be seedlings, but named varieties, 

 grafted or budded. 



