44 
AN INVESTIGATION INTO THE 
specimen, which was rather darker in color. Two series of compression 
determinations were made on each of these prisms. Eight series of measure- 
ments were thus made of vertical compression and five of lateral extension. 
In the second specimen of the rock, D was found to have a rather higher 
value than in the case of the first specimen, although prism d, cut from the first 
specimen, approaches this value closely- The duplicate determinations made 
on each of the prisms agree very closely with one another. The results of 
the measurements are given in the table on page 44 . 
The average of the values obtained in the case of the first specimen are as 
fpllows : 
E 6,747,000; <T = 0.2152; D= 3,984,000; C= 2, 781, 600. 
The average of those obtained from the second specimen are as follows : 
E= 8,247,500; * = 0.1977; D = 4,555,000; C= 3,445,000. 
In this case, as has been mentioned, the two specimens represent different 
varieties of the Quincy granite. The stress strain curve given by specimen b 
is shown in figure 16. In this figure, I represents longitudinal compression 
and II lateral extension. 
9000 
7OOO 
5000 
3OOO 
1000 
40 80 120 160 200 24O 
32O 36O 
FIG. 1 6. Quincy Granite. Stress-strain curves. 
GRANITE, STANSTEAD, PROVINCE OF QUEBEC, CANADA. 
This is a fine-grained gray granite, which occurs as a large intrusive 
mass cutting strata of lower Paleozoic age. It is extensively quarried and is 
largely used as building material and for paving sets in the city of Montreal. 
It is biotite muscovite granite, having as its essential constituents ortho- 
clase, quartz, and biotite, but containing also a rather small amount of 
muscovite and epidote, both of which occur as skeleton crystals of consider- 
able dimensions, for the most part growing in the feldspar and apparently 
of secondary origin. The rock is very fresh, being almost entirely free from 
the usual decomposition products. In addition to orthoclase, the rock con- 
