AN INVESTIGATION INTO 
The stress-strain curves obtained from specimen a are given in figure 15. 
In this figure, I represents longitudinal compression and II lateral extension. 
9000 
7000 
-5000 
3000 
1000 
BO 120 160 20O 24O 28O 32O 36O 
5 TRAIN 
40 
FIG. 15. Westerly Granite. Stress-strain curves. 
The averages of the values obtained are as follows : 
= 7,394>5oo; <r = 0.2195; D = 4,397,500; C= 3,019,700. 
The differences between the highest and lowest values in the four determi- 
nations of .Don specimen d was only 280,000. Of the other columns a gave 
on an average somewhat lower, and 6 somewhat higher results. 
GRANITE, QUINCY, MASSACHUSETTS, UNITED STATES. 
The rock is a rather coarse grained gray granite composed very largely of 
microperthite and quartz. The iron-magnesia constituents are represented 
by a very deep green, almost black, hornblende, associated with which there 
appears to be a smaller amount of a very dark colored pyroxene. These dark 
constituents belong to the alkali-rich varieties of their respective families and 
are so opaque that it is difficult to determine their precise character. They 
are also very irregular in shape, occupying corners between the feldspar grains 
and often penetrated by crystals of the microperthite, showing that they 
separated out later than the feldspar. The quartz shows strong undulatory 
extinction. The rock is fresh and unaltered. 
A color-process photograph of a polished surface of the Quincy granite is 
shown in Plate IX A, and a photomicrograph of a thin section taken between 
crossed nicols in polarized light and magnified 30 diameters is reproduced in 
Plate IX B. 
Two large specimens of the rock, which differed slightly from one another in 
appearance, were secured and examined. Three square prisms, a, c and d, 
were prepared from one specimen and one square prism, b, from the other 
