46 



THE COMMERCIAL HICKORIES. 



buggy wheels have been made of catalpa, this wood will never replace 

 hickory, because it has only about one-half the strength of good 

 hickory. 



No timber has been found which has both the strength and shock- 

 resisting qualities of hickory. This is especially true of small ma- 

 terials, such as rims, spokes, and ax handles. 



FACTORS THAT AFFECT STRENGTH. 



MOISTURE. 



Table No. 15 shows the effects of moisture on strength. The 

 strength at maximum load represented by the modulus of rupture 

 is about doubled by drying, and the shock-resisting ability, or work 

 to maximum load, is slightly decreased, due to the great decrease in 

 bending of the dry material. 



TABLE 15. The effect of moisture on strength of hickory from all localities. 



