52 THE COMMERCIAL HTCKORIES. 



value of the wood in the tree. This procedure is, however, not pos- 

 sible with American woods, because silvical conditions have not 

 become constant, and the origin and history of the tree are unknown. 



Figure 15 shows the results of tests to determine the strength in 

 relation to the distance from the center of the tree. In normal trees, 

 the strongest wood appears to be from 5 to 7 inches out from the 

 center of the tree, and wood of greatest shock-resisting ability is nearly 

 in the center; consequently the wood 3 to 7 inches from the center 

 of the tree is the best. However, suppression and slow growth in 

 youth, followed by exposure to light and fast growth in old age, will 

 disturb these relations, and under such conditions the best wood may 

 be found near the outer part of the tree. 



The entire merchantable boles of two trees were used to determine 

 the relation of height above ground to strength and toughness (see 

 fig. 16). The butt cuts were toughest but not strongest; the strong- 

 est wood was from 21 to 30 feet above the ground. The toughest 

 wood is in the butt, and above the butt the technical value of the 

 wood remains practically constant up to the base of the crown, where 

 it becomes less valuable.. 



AGE. 



Trees about 150 years old have the maximum average strength, 

 but the average work to maximum load is less with increasing age, 

 and the youngest trees are toughest. Therefore, to obtain the best 

 wood the trees should not be allowed to become overmature. 



SOIL AND SITUATION. 



In some regions there are many small, stunted hickories, which 

 most users will not touch. They have narrow sap, are likely to be 

 birdpecked, and show very slow growth. Yet five of these trees 

 from a steep, dry south slope in West Virginia had an average strength 

 fully equal to that of the pignut from the better situation, and were 

 superior in toughness, the work to maximum load being 36.8 as 

 against 31.2 for pignut. The trees had about twice as many rings 

 per inch as others from better situations. 



This, however, is not very significant, as trees of the same species, 

 age, and size, growing side by side under the same conditions of soil 

 and situation, show great variation in their technical value. . It is 

 hard to account for this difference, but it seems that trees growing 

 in wet or moist situations are rather inferior to those growing on 

 fresher soil; also, it is claimed by many hickory users that the wood 

 from limestone soils is superior to that from sandy soils. 



GEOGRAPHIC LOCATION. 



One of the moot questions among hickory men is the relative 

 value of northern and southern hickory. The impression prevails 

 that southern hickory is more porous and brash than hickory from 



