6o 
AN INVESTIGATION INTO THE 
As will be seen, the values obtained for D in this rock are considerably higher 
than those yielded by any other rock of the series examined. In the six 
independent measurements carried out on the first three specimens, the 
difference between the highest and lowest values for D amounted to 830,000 
pounds, while on the four measurements made on specimen d there is a 
rather greater difference amounting to 845,000 pounds. 
The averages of the determinations made on each of these columns are as 
follows : 
B 
D 
ff 
c 
(I 
I -? c I c QOO 
10 400 ooo 
o 2838 
e 27O OOO 
b 
1 4 1 70 ooo 
IO Q4S OOO 
o 2840 
c c 2 ^ OOO 

1 4 1 7O OOO 
1 1 085 ooo 
o 2870 
5 CQC OOO 
d 
I -2 IQ7.7SO 
10 076 ooo 
o 2812 
= I cc OOO 
A\ 7 erage 
1.3,763,187 
10,626,500 
o . 2840 
5,363,750 
The stress-strain curves given by a specimen this rock are shown in figure 
23. As will be seen from these curves, in its approach to perfect elasticity the 
rock is comparable to plate glass. 
9000 
1000 
40 80 >2O 160 ZOO 24O 
5 TRA IN 
. 23. Sudbury Diabase. Stress-strain curves. 
SANDSTONE, CLEVELAND, OHIO, UNITED STATES. 
This is a fine and even grained yellowish sandstone used very extensively for 
building purposes. The bedding is marked by a slight variation in color 
in different beds. The prism of the rock used in determining its elastic 
constants was cut from a single bed of uniform character and color, and was 
taken in the plane of the bedding. A color-process photograph of a smooth 
surface of the rock is shown in Plate XVI A . 
Under the microscope it is seen to be a typical highly f eldspathic sandstone. 
The constituent minerals are present in grains which arejjjapproximately 
