114 Adams and Coker — Elastic Constants of Rocks. 



represents in all cases the longitudinal compression and II the 

 lateral extension. The hysteresis is greater than in the case 

 of the black Belgian marble (fig. 7), but about the same in 

 amount as shown by the Vermont marble and the Trenton 

 limestone from Montreal. 



9000 



1COO 



^5000 



1000 











R 



I 







































40 



BOO 



80 120 160 



STRAIN 



Fig. 6. Carrara Marble, stress strain curves. 



240 



9000 



^7000 



-J 

 ($5000 



o 



3000 



1000 













^/\ 







































40 80 120 160 200 240 



STRAIN 



Fig. 7. Black Belgian marble, stress strain curves. 



Granite, Westerly, Rhode Island, U. S. A. 



Four test pieces were used in measuring the elastic constants, 

 viz : two square prisms, a and b, and two round columns, c 

 and d. Two sets of determinations were made on each of the 

 first three specimens, the instruments being attached to dif- 

 ferent pairs of sides in each case, and four sets of determina- 

 tions were made on specimen d in planes making angles at 45° 

 with one another. The results are given in the following 

 table. 



