370 
PROFESSOR F. D. ADAMS AND DR. J. T. NICOLSON 
jedenfalls grosser als die Festigkeit, aber auf verschiedenen Seiten nicht gleich gross 
ist, so dass Ausweichen seitlich zum Maximaldruck stattfinden kann. 1st das 
vorhandene Druckminimum kleiner als die Festigkeit, so tritt Zerbrechen und damit 
Ausquetschen, ‘ Umformung mit Bruch,’ ein.” In rock movement resulting from 
these several factors the additional factor of time may play an important part. 
Whether all these factors, or only certain of them, are actually necessary for the 
production of rock deformation is unknown, but can probably be determined by 
experiment. For by experiment the action of each may be studied separately, as 
well as in combination with the others. 
In experimental work, therefore, the first condition to be reproduced is that of a 
differential pressure which, even in the direction of its minimum value, exceeds the 
elastic limit of the rock under investigation. The action of this pressure should then 
be studied when combined with heat, and then with heat in the presence ol moisture. 
Finally, the effect of time or rapidity of motion should be investigated. 
III. Deformation of Carrara Marble, 
a. Methods employed. 
In the present paper* a first contribution to such a study is presented, pure 
Carrara marble being the rock selected. At the outset the endeavour was made to 
submit this rock to the first of the three conditions above mentioned only—that is, to 
bring to bear upon it great pressure from all sides, a pressure, however, which should 
not be equally great in every direction, but which, while always exceeding the elastic 
limit of the rock, should be greater in one direction than in others, thus tending not 
merely to bring about cubic compression but to determine a flow of the material in 
one direction. For this purpose it was sought to enclose the marble in some material 
having a much higher elastic limit than the rock itself, and possessing at the same 
time a very considerable ductility, so that it would move without rupture when the 
pressure became sufficiently high. Under such conditions it was believed the marble 
could not break in the ordinary way, even when submitted to a pressure far above 
that which under ordinary conditions would be required to crush it, for it would be 
enclosed on all sides by a stronger substance, and the pressure being increased it would 
remain intact until the elastic limit of the enclosing material had been exceeded, when 
it would commence to move, acting as water or any other enclosed fluid might. 
As it was proposed to extend the investigation eventually to granites, and possibly 
other rocks, a long series of experiments was made on various alloys in the endeavour 
to obtain a material which possessed a sufficiently high elastic limit combined with 
the necessary ductility to fulfil the requirements as enclosing material in all cases; 
* A preliminary notice of these experiments was read before Section C of the British Association for 
the Advancement of Science, at the Toronto Meeting in 1897, an abstract of which appears in the ‘Pro¬ 
ceedings ’ of the Association for that year, 
