244 P. W. Bridgman— Failure of Cavities in Crystals 



ter was not just what I had expected, and indicated that 

 a systematic examination of the whole subject was neces- 

 sary. Among other things, it was evident that a rock is 

 too complicated a structure to give information on the 

 various elements of the problem. The first experiments 

 should obviously be performed on the homogeneous mate- 

 rials of which a rock is composed, that is, on individual 

 crystals. But the preparation of individual crystals was 

 at that time beyond my resources, and I allowed the mat- 

 ter to drop. 



The whole problem was again foiced on my attention 

 by Dr. George F. Becker, who had for some time recog- 

 nized its importance and had published results obtained 

 by quite a different method. Dr. Becker's interest in the 

 problem was so great that he was willing to undertake 

 all the arduous work of superintending the preparation 

 of the specimens, leaving to me the easy task of making 

 the actual experiments. He procured an appropriation 

 from the National Academy of Sciences, which, with the 

 kind cooperation of Dr. Stratton, made it possible to 

 secure the services of the optician of the Bureau of Stand- 

 ards, Mr. Clacey. He personally selected many of the 

 specimens from the resources of the National Museum, 

 which were at his disposal ; specimens both of single crys- 

 tals and of several rocks were prepared. Without his 

 interest and assistance this paper would not have been 

 possible. 



This paper presents, then, results on the crushing of 

 hollow cylinders of single crystals and rocks by the 

 application of hydrostatic pressure to the external sur- 

 face. The results are not of immediate geological appli- 

 cability, because the conditions of the experiment are not 

 duplicated in the field, but they suggest the nature of the 

 effects to be expected under actual conditions. Apart 

 from their geological interest, the results have an intrin- 

 sic interest from the points of view both of theory of elas- 

 ticity and of the structure of crystals. Very few experi- 

 ments have ever been made on the rupture of crystals ; in 

 fact the nature of the symmetry relations has not yet been 

 worked out. From the point of view of the mathematical 

 theory of elasticity the problem of the stress-strain rela- 

 tions in a crystalline cylinder under the conditions of the 

 experiments seems never to have been discussed. I have 

 been able to obtain the solution in several of the simpler 



