ELASTIC CONSTANTS OF ROCKS. 
Black Belgian Marble. 
Size 
.96X.96 
.96 
Area 
.922 
E 
11,070,000 

.278 
D 
8,303,000 
c 
4,330,000 
Load (in pounds). 
Longitudinal 
compression 
(multiply 
readings by 4 
for millionths). 
Lateral 
extension 
(millionths). 
1,OOO 
o 
O 
2 OOO 
25 
24. 
3 ooo 
5^ 
51 
4. OOO 
84. 
76 
c OOO 
116 
IOT 
6 ooo 
14-7 
I2Q 
7 OOO 
178 
I 55 
8 ooo 
2IO 
182 
OOO . 
240 
209 
8,000 
211 
183 
7,000 
6,000 
1 80 
148 
157 
131 
5,000 . . 
118 
104 
4. OOO 
88 
78 
-2 OOO 
57 
SI 
2 OOO . . . 
T.Q 
2^ 
1,000 
I 
4 
The elastic constants were found to be as follows : 
E= 10,070,000; ^ = 0.278; 17=8,303,000; 
9000 
^7000 
ft3 
*j 
^5000 
30OO 
1000 
40 
80 120 
STRAIN 
160 
200 
= 4,330,ooo 
FIG. 6. Black Belgian Marble. Stress-strain curves. 
A plot of the readings is given in figure 6, from which it is clearly seen that 
the rock is practically free from hysteresis, and that within the range of pres- 
sures employed its elasticity is almost perfect. I represents longitudinal 
compression and II lateral extension. 
