478 Adams db Coker — Investigation into the Flow of Bocks. 



allel to the walls, thus following the direction of movement 

 which would be developed in any plastic mass when flowing 

 away from between the advancing pistons in a confined space 

 such as that afforded by the deformation of the enclosing 

 tube. A microphotograph of this deformed marble is shown 

 in Plate III I. 



Another experiment similar to that just described was car- 

 ried out with a column of marble of the same size enclosed in 

 a nickel-steel tube with a wall thickness at the thinnest part of 

 •19 inch (-5 cm ). This required a pressure of 221,160 lbs. per 

 square inch, which increased the diameter of the column to 

 36*7 per cent. In this the same structure was developed in 

 the marble as in the case of the experiment just described, but 

 the deformation being smaller, the foliation developed in the 

 rock was not quite so marked. 



(c) Strength of the marble after deformation at ordinary 

 temperatures. 



A series of columns of Carrara marble of the size regularly 

 employed, namely 1*575 inch (4 cm ) long and about '814 inch 

 (2 cm ) in diameter, with a slight taper, were prepared and were 

 put into a series of tubes made of a mild carbon steel. The 

 walls of the tube were *592 inch (l'5 cm ) thick, except in 

 the central portion of the marble, where for a length of -688 

 inch (l*75 cm ) the wall was thinned away to -13 inch (*33 cm ) so 

 as to localize the bulging here. The pistons were then put 

 into the tubes in the usual way and the marble deformed so as 

 to give the column a barrel-shaped form having a diametral 

 enlargement of as nearly as possible *2 inch (-508 cm ), or 24*5 

 per cent. This deformation was produced in one minute, a 

 100 ton Buckton testing machine being employed. The max- 

 imum load required to complete the deformation at this rate 

 of speed averaged about 56,000 lbs. (25,390 kilos.). This very 

 rapid deformation severely tested the steel tubes, a number of 

 them splitting before the required deformation was secured 

 and being therefore rejected. Eighteen such experiments 

 were made, eleven of which were successful, the tube remain- 

 ing unruptured. The steel tubes were turned off as soon as 

 possible after the conclusion of the experiment and the bulged 

 columns of marble thus set free. Of these the first two having 

 been carefully measured were at once tested in compression to 

 ascertain their strength. In each case the load at which the 

 first splitting of the marble took place was noted and then the 

 load under which the column finally broke down. 



The next three columns were allowed to stand for 100 days 

 (or 2400' hours) and were then tested in the same manner. 

 Four others, after having been freed from the enclosing steel 



