34 
AN INVESTIGATION INTO THE 
holes" and "second holes ") . In column d four sets of holes were drilled, so as 
to carry out measurements on four diametral planes, making angles of 45 
with one another. The first set of holes, however, were defective, so measure- 
ments were made on the second, third, and fourth sets only. On column e a 
single set of measurements was completed when the column broke. 
In this way ten measurements of vertical compression and six of lateral ex- 
tension were obtained. The results are presented in the table on page 35. 
The averages of the results obtained are as follows: 
E= 6,833,000; ff = 0.2528; D= 4,604,000; C= 2,724,800. 
The difference between the highest and lowest results obtained for D 
amounts to 500,000. 
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3 TRAIN 
FIG. ii. Baveno Granite. Stress-strain curves. 
As mentioned in the chapter on the "Application of the Method of Simple 
Compression to the Case of Rocks, " in order to obtain consistent and reliable 
results, the specimen of the rock and for that matter the same is true of the 
specimen of any metal if its elastic constants are to be determined must 
first be bought to "state of ease" by loading and unloading it several times 
in succession, employing each time a pressure equal to the maximum load to 
which the specimen is to be subjected, when the measurements are subse- 
quently made. 
As a matter of interest in the case of the Baveno granite (as well as in that 
of the Stanstead granite referred to later), readings were taken during the first 
four cycles of compression, when this state of ease was being induced, and 
the results are presented graphically in figure 12. 
