ELASTIC CONSTANTS OF ROCKS- 
47 
Table showing comparative strength oj Stanstead Granite. 
Specimen. 
Dimensions. 
Area. 
Weight. 
Actual 
load at 
initial 
failure. 
Load per 
sq. in. at 
initial 
failure. 
Max. 
load. 
Max. 
load 
per sq 
inch. 
Granite, M 
St. Philip, Quebec. . \B 
Inches. 
2.56 by 2.55 by 2.66 
2.47 by 2.46 by 2.52 
Sq. In. 
6.528 
6.076 
Lbs. 
5915 
.441 
Lbs. 
113,000 
115,000 
Lbs. 
17,310 
18,926 
Lbs. 
124,300 
142,800 
Lbs. 
18,040 
23,500 
Essexite, {A 
Mt. Johnson, Quebec \B 
2.47 by 2.68 by 2.54 
2.48 by 2.56 by 2.56 
6.619 
6.368 
.700 
636 
138,000 
141,000 
20,849 
22,141 
148,700 
167,700 
22,465 
26,334 
Granite, / A 
Stanstead, Quebec . . \ B 
2.61 by 2.50 by 2.52 
2.56 by 2.55 by 2.47 
6.525 
6.528 
.565 
511 
92,700 
88,300 
92,700 
89,300 
14,206 
13,526 
latter is taken in ordinary light and magnified 2 7 diameters. The fact that this 
photomicrograph is taken in ordinary light, while those of other granites 
just described are taken between crossed nicols, gives this rock an appear- 
ance of being coarser in grain than it really is, owing to the boundaries of 
the colorless constituents being ill-defined. The size of the grain may be 
seen, however, by comparing the dimensions of the iron-magnesia constituents 
of the rocks or still better by comparing the grain of the several rocks as shown 
in the photographs of the polished surfaces. 
9000 
. 7000 
:sooo 
3000 
J000< 
4O 90 120 160 20O 24O 26O 32O 360 
S TRAIN 
FIG. 1 8. Stanstead Granite. Stress-strain curves. 
400 
440 43O 
NEPHELINE SYENITE. 
NEPHEUNE SYENITE, CORPORATION QUARRY, MONTREAL, CANADA. 
This is a typical nepheline syenite which forms a portion of Mount Royal, 
one of the Monteregian Hills and which cuts an earlier intrusion of essexite 
like that to be described later from Mount Johnson. 
It is a hard and tough rock used as road metal on the streets of the city of 
Montreal. It is rather light gray in color and often shows locally a more 
