APPLICATION OF GRAPHIC METHODS 



315 



to have no weight or inertia ; the effect of these elements may 

 then be treated as equivalent to the effect of four external forces, 

 la 1/9. and 6a 6/9. The dynamic frame for this case will be a 

 polygon of eight sides, Fig. 35, 2a 2/9. 3a 3/9, 4a 4/9. 5a 5/9, 



Fit) 33 



:, 



having its angles on the lines of load, and so inclined as to be 

 in equilibrium under these loads. The stresses in each link are 

 the pressures at each joint. The reciprocal figure for this frame 

 is shown in Fig. oou. The inclinations of the links are no longer 



