1916] on Polarized Light and its Applications to Engineering 587 



faces of small specimens are sometimes faced by aid of a surface plate 

 in order to give a uniform bearing. In a large specimen, where this 

 process becomes very laborious, it is often faced with piaster -of -Paris, 

 and plates of millboard are sometimes interposed in addition, to give 



25. 



Q. 75 > 



Fig. 6. — Load applied by Eivet. Experimental Results, 



a uniform bearing area between the pressure plates of a testing- 

 machine and the specimen. 



It is difficult to experimentally determine the distribution of 

 stress in a short block of an engineering material, but if a transparent 

 model is used the problem is comparatively simple ; and it may there- 



