THE MECHANICAL INTERPRETATION OF JOINTS 711 



Fig. 2. — A. Arrangement used in one of Hartmann's experiments in which the 

 test piece (in the center) was subjected to uniform compression over its whole base, 

 while the upper surface suffered compression in the center only. (L. Hartmann, 

 1896.) B. Liiders' lines produced in the experiment illustrated in Fig. 2 A. (L- 

 Hartmann, 1896.) C. The theoretical lines of stress (bisecting the angles of Liiders' 

 lines) reconstructed on the test piece illustrated in Fig. 2B. (L. Hartmann, 1896.) 



