210 Benton — Experimental Method in the Flow of Solids. 



It will be observed that the wires became considerably flat- 

 tened in the last stages of the flow, and that slight wavy irregu- 

 larities in their form appeared, probably on account of imper- 

 fect homogeneity of the material. It is possible, however, to 

 follow in the figures the general character of the motion, from 

 the first stages of the flow to the last. At first the flow does 

 not differ in any essential respect from what might be expected 

 in view of the shape taken by the surface of the cube. But as 

 the flow proceeds, the wires near the middle of the cube take 

 the form of curves with two points of inflection, as shown in 

 Hg. 5, and less distinctly in fig. 7. In figs. 7, 5, and 3, a shear- 

 ing of the cube parallel to the plates of the testing machine is 

 apparent ; the upper part has moved to one side, and the lower 

 part to the other. These results are not surprising, because 

 compression without such shearing would represent an unstable 

 state of motion ; if any cause should slightly displace the lower 

 part of the cube with respect to the upper part, perpendicu- 

 larly to the direction of the compression, then further com- 

 pression would tend to increase such a displacement. 



In view of this complication, it does not seem worth while 

 to attempt to apply to the compression of a cube the mathe- 

 matical theory of the flow of solids, as developed by Tresca 

 and Saint Tenant.* 



University of Chicago, 

 September, 1901. 



* Comptes rendus, lxvi, pp. 1027-1032, 1244-1246, 1305-1324; Ixviii, pp. 

 221-237, 290-301 ; Ixx, pp. 309-311, 473-480; etc. 



