Sven Wickseil 



Y 



-4 -3 -2 -7 O */- *2 +J + -jt 



Fig. 2. Frequency curve of the' linear motions as projected on the axis toward vertex I. 



Y 



-4 -J -2 -7 O */- +2 *J *4 



Fig. 4. Frequency curve of the linear motions as projected on the axis toward vertex III. 



