38 AN INVESTIGATION INTO THE 
given by b are shown in figure 13. Of these curves, I represents longitudinal 
compression and II lateral extension. 
The averages of the results obtained are as follows : 
=8,295,000; (7=0.2112; D= 4,792,000; C= 3, 399,000. 
The difference beween the highest and lowest values obtained iorD amounts 
to 380,000, or if one abnormally low determination be omitted the differ- 
ence is 1 10,000. 
GRANITE, UI,Y LAKE, PROVINCE OF NEW BRUNSWICK, CANADA. 
A typical rather coarse-grained pink granite. Under the microscope it is seen 
to present the usual hypidiomorphic structure of this rock, and to be composed 
of biotite, microperthite, and quartz as essential constituents . A small amount 
of plagioclase occurs as an accessory constituent. There are also a few minute 
crystals of a highly doubly refracting mineral which has also a high index of 
refraction, and apparently crystallizes in square prisms. This is probably 
zircon or possibly monazite. 
The feldspars and quartz preponderate largely. The microperthite, which 
is the most abundant constituent in the rock, is composed of a minute inter- 
growth of two feldspars, in neither of which can twinning be detected. One 
is, in all probability, orthoclase and the other albite. The former is more or 
less turbid from the presence of alteration products, such as are commonly 
found in this mineral species, while the latter is clear and fresh. The quartz 
shows marked undulatory extinction as in the case of the Westerly granite. 
The biotite is fresh and deep brown in color. 
This rock is, as stated above, a typical granite, rather coarse in grain, and 
which has undergone but very little alteration. 
A color-process photograph of a polished surface of the rock is seen in Plate 
VII A and a photomicrograph of a thin section magnified 30 diameters and 
taken between crossed nicols in polarized light, is shown in Plate VII B. 
Two square prisms of the rock were prepared and their elastic constants 
determined. The results are given in the table on page 39. 
The stress-strain curves given by specimen c are shown in figure 14. In this 
figure I represents longitudinal compression and II lateral extension. 
The means of the results obtained are as follows : 
E= 8,165,000; <r= 0.1982; >= 4>5i7,5oo; C= 3,380,000. 
The difference between the two determinations of D is only 105,000. 
