36 



Significance of results. 



From the cross-breaking tests are obtained the cross-breaking- inodnhis of rupture, the 

 modulus of elasticity, or measure of the stiifuess, and tlie clastic resilience, or measure of the 

 toughness. 



The loads and their corresponding deflections are plotted as rectinigiilar ((uirdinates, and the 

 modulus of elasticity and the elastic resilience are obtained from a study of this strain diagram. 



The following is an example of the record made for every beam test. This is a record of a 

 test made on a 4 by 8 inch stick of long- leaf pine, 12 feet long, which was ])laced on supi)orts 140 

 inches apart. 



(16 

 Mark /3 



(1 

 Length, 140.0 inches. 

 Height, 8.04 inches. 

 Breadth, 4.02 inches. 



CROSS-BREAKING TKST. 



I Strength of Extreme Fiber, 



3 Wl 

 where/= ,^ = 10,910 pouuils per si|U;ire inch. 



Modulus of Elasticity ^ 2,070,000 pduuds per s(iuar6 inch. 

 Total Kesiliencc ^= 35,440 inch-pounds. 

 Resilience, per cub. in. = 7.83 inch-pounds 

 Total Elastic Resilience = 8,650 inch-pounds. 

 Elastic Resilience, per cubic inch = 1.91 iu(li-))ouuds. 



[Number of animal rings per inch = 14.] 



Scale 

 reading. 



11.02 

 11.19 

 11. 3.') 

 11.51 

 11.07 

 11.81 

 11.98 

 12. 12 

 12.3] 

 12.50 

 12.78 

 13.12 

 13.70 

 14.70 



Remarks. 



Top end. 



Maximmn load. 



■Deflection 1 in inches. K 



E 4 



