Vibrations elucidated by Simple Experiments. 253 



pendulum equivalent to each actual pendulum CB and let 

 the droop DC of the bridle itself be (31. At time t let the 



Fig. 1. 

 Side Elevation. 



Fig. 2. 

 End Elevation. 



Double-Cord Pendulums. 



planes AG and A'O' of the bridles be inclined o> from the 

 vertical, let the pendulums be inclined 9 and yjr, the linear 

 displacements of their bobs of masses P and Q being y 

 and z. 



Then their equations of motion for small oscillations may- 

 be written 





df 2 

 But 6 and i^ are respectively 



(25) 

 (26) 



y-f3lco 



and 



jSlco 



I "~~ I 



Further, neglecting the masses of the cords ACA, A'C'A' 

 and of the connector CO', we see that o> satisfies the 

 equation : 



-pc,(e-o>)=Qc,(o>-f), 



so that 



°"-(l-r/3XP + Q) 

 Phil. Mag. S. 6. Vol. 34. No. 202. Oct. 1917. T 



