480 Adams <& Coker — Investigation into the Flow of Rocks. 



tube, were heated in a water bath for 24 hours and then tested. 

 The last two, after being freed from the steel tube, were main- 

 tained at a temperature of 350° C. for 20 hours and then tested 

 as before. 



Eight columns of the original marble, cut to the same barrel- 

 shaped form and having the same average dimensions as those 

 resulting from the one minute squeezes just described, were 

 then prepared, and these also were tested in compression to 

 ascertain their strength. It was found that these, instead of 

 first splitting and then breaking down as in the case of the 

 columns of deformed rock, showed no signs of preliminary 

 rupture, but gave way suddenly and completely. 



The results obtained, together with certain others to be 

 referred to later, are given in the table on page 479. 



It will be seen that when the marble is deformed in the 

 manner described, the deformation being accomplished in one 

 minute and tested so soon as the enclosing tube can be removed, 

 it retains 60*6 per cent of its original strength. 



In order to ascertain whether the deformed marble would 

 be stronger if the deformation were carried out at a higher 

 pressure, a column of the Carrara marble having the same 

 dimensions as those above described was deformed in a heavy 

 tube of nickel steel having a wall thickness of '197 inch ("5 cm ) 

 at the thinnest part. The deformation was carried out a little 

 more slowly than in the case of the experiments above described, 

 occupying 100 minutes, and the load required to effect the 

 deformation was 115,000 lbs. Upon the completion of the 

 experiment the deformed column, having been freed from its 

 enclosing tube, was tested in compression and was compared 

 with a column of the original marble cut to the same dimen- 

 sions. The deformed column measured 1*07 inch (2'72 cm ) in 

 diameter, which represents a diametral enlargement of 31*4 per 

 cent. The loads required to crush the two specimens respect- 

 ively were as follows : 



Original marble... 6525 lbs. (2954 kilos.) 



Deformed marble 5470 " (2479 " ) 



The deformed marble thus retains 83*8 per cent of its original 

 strength. The experiment was then repeated with three other 

 columns and almost identical results obtained. 



It will thus be seen that the increased pressure (accompanied 

 by a somewhat slower rate of deformation) led to a greatly 

 increased strength in the case of the deformed marble, the 

 strength increasing from 60*6 per cent to 83'8 per cent. 

 . In three other experiments an attempt was made to ascer- 

 tain whether, if the marble were deformed under a still higher 

 pressure, a still further increase in strength might be secured. 



