APPEARANCE AND CHARACTERISTICS. 



25 



annual rings are difficult to distinguish, since the temperature changes 

 from season to season are not marked enough to form the distinct 

 bands of spring and summer wood common in eastern oaks. In the 

 case of the lumber, it becomes impracticable to attempt to obtain the 

 rate of growth of different pieces. 



STRENGTH. 



The material used in the tanbark oak tests was divided into three 

 classes or shipments, differing in the age of the trees and the season 

 of cutting. The first two shipments were selected in the summer 

 during the peeling season, and represented in the first shipment the 

 larger and more mature trees of the stand, and in the second shipment 

 the smaller and younger trees. The third shipment was felled in 

 October and represented the same wood as that obtained in the first 

 shipment, but felled in the season when the bark was tight, or when 

 the sap was not running. 



The strength of the wood in several conditions of seasoning is 

 shown in Table 11. The three shipments had practically the same 

 strength and, therefore, were combined in the table. 



TABLE 11. Strength of small clear pieces of tanbark oak, green, air-dry, and kiln-dry, 



size 2 by 2 inches in section. 



GREEN. 



AIR-DRY (10 TO 20 PER CENT MOISTURE). 



KILN-DRY (5 TO 10 PER CENT MOISTURE). 



