588 



Professor Ernest G. Coker 



[Feb. 18, 



fore be of interest to indicate what progress has been made in the 

 solution of this practical problem bj. Professor Filon and myself. 



In the majority of testing machines the mechanical arrangements 

 for applying a pure compression load are defective, and for investiga- 

 tions of this kind a special form of testing-machine was devised and 

 constructed to give a very accurately appHed load. The general 

 arrangement of this machine is shown in sectional elevation (Fig. 8), 

 in which A and B are two substantial blocks worked to true planes 



Fig. 7.— Load applied by Rivet. Principal Stresses. 



at their opposing faces. One of these, A, may be fixed or capable 

 of a small movement along the normal to the working face by means 

 of the screw C. The other, B, is secured to a block carried by two 

 flexible diaphragms DD, spaced at a considerable interval, and clamped 

 at their outer edges in the framing of the machine in such a manner 

 that the motion of the pressure-plate has only one degree of freedom, 

 and is limited by the elastic deformations of the diaphragms. The 

 applied load is weighed by a lever svstem E, and, as the work done 



