374 
PROFESSOR F. D, ADAMS AND DR, J. T. NICOLSON 
in all directions. It differs somewhat in appearance from the original rock in possess¬ 
ing a dead white colour, somewhat like chalk, the glistening cleavage surfaces of the 
calcite being no longer visible, and the difference being well brought out in certain 
cases owing to the fact that a certain portion of the original marble often remains 
unaltered and unaffected by the pressure. This, when present, has the form of two 
cones of obtuse angle, whose bases are the original ends of the column resting against 
the faces of the steel plugs, while the apices extend into the mass of the deformed 
marble and point toward one another. These cones, or rather parabolas of rotation, 
are developed, as is well known, in all cases where cubes of rock, Portland cement, or 
cast iron are crushed in a testing machine in the ordinary manner. In the present 
experiments they seldom constituted any large joroportion of the whole mass, and in 
some cases are absent or but faintly indicated, but there is always in immediate con¬ 
tact with the ends of the steel plugs a thin cake at least of marble possessing the 
characters of the original rock. 
In order to ascertain the strength of the deformed rock as compared with the 
original marble, and also whether, in the case of the former, the rate of deformation 
influenced the strength, three of the half columns, obtained by splitting the deformed 
columns as above described and freeing them from the collar, were selected and 
tested in compression by means of an Emery testing machine. The results are pre¬ 
sented in the following table, the measurements being given in inches :— 
Original 
height. 
Original 
diameter. 
Greatest di¬ 
ameter after 
deformation. 
Time of 
deformation. 
Crushing load for 
deformed marble, 
lbs. per square inch. 
Experiment A ... 
1-594 
1-000 
1-407 
64 days 
5350 
„ o... 
1-594 
1-000 
1-203 
If hours 
4000 
„ P-. 
1-505 
1-000 
1-388 
10 minutes 
2776 
As already mentioned, columns of the marble of the original dimensions, namely, 
1 ‘5 inch high and 1 inch in diameter, were found to have a crushing strength of 
between 11,430 and 12,026 lbs. per square inch. These figures show that, making 
all due allowance for the difference in shape of the specimens tested, the marble, after 
deformation, while in some cases still possessing considerable strength, is much 
weaker than the original rock. They also tend to show that when the deformation 
is carried on slowly the resulting rock is stronger than when the deformation is rapid. 
The specimens of the deformed rock when tested, in all cases crushed in exactly the 
same manner as the columns of the original marble, namely, with the development of 
two cones whose bases are the end faces of the columns, and whose apices point 
toward one another, with the appearance, when the limit of strength is reached, of a 
series of inward curving cracks running from top to bottom of the specimen along 
which strips of the rock split away from the cones in question. These cones while in 
