258 Prof. Barton and Miss Browning on Coupled 



lath pendulum consists of: two screw points resting in a hole 

 and slot in a metal plate. The two bobs P and Q are the 

 same as those used in the double-cord pendulum, viz., metal 

 rings with glass funnels for sand. The boards shown just 



Fie:. 3. 



Cord and Lath Pendulum. 



beneath the funnels are fixed on the same wooden carriage 

 and are capable of simultaneous slow motions on horizontal 

 rails perpendicular to the plane of the diagram. This motion 

 is effected by the rotation of a wheel whose axle winds a 

 cord attached to the carriage. The whole arrangement 

 is shown by the photographic reproduction fig. 5 of 

 Plate IV. 



Equations of Motion and Coujiling. — For the cord and lath 

 peudulums let the masses of the bobs be P and Q, the 

 lengths of the simple pendulums equivalent to PR and QS 

 be respectively r and s and at time t let their angular 

 displacements be 6 and ijr, the linear displacements of their 

 bobs being y and z. Further, let as denote the distance PS 

 between the movable and fixed points of suspension. 



Then for small oscillations we may assimilate sines to 

 angles and regards the total tensions of the cords as always 



