Triple Pendulums with Mutual Interaction. 617 

 Table of Experimental Details. 



Photograph Length Length Length Length Length Length 



Letter. AB. A'C. AF. A'G. \<K. DE. 



fin. cm. em. em. cm. cm. 



Uainff fA 52 71 84 KM) 98 81 



Three ' B and B -'" 52 7l S4 l0 ° 98 ,; ' 



Connector 



i G 18 71 84 100 98 02 



I D andE... IS 71 86 100 L06 68 



^F.G.andH 18 71 8(5 100 106 30 



Using (1 18 71 86 100 106 



Two j J 32 75 86 100 106 



Connectors. { K and L... 31 31 S6" 100 106 



^MandN... 41 41 86 100 106 



The table indicates that for photograph A (PI. XI.), the 

 coupling due to the bridle droop is small, but, for this droop, 

 that due to the connectors is large. The vibrations were 

 produced by drawing aside the pendulum P at the point F. 

 The traces from the three bobs P, Q, and R all show that 

 there are more than two simple harmonic motions combining 

 to produce the curves. 



For the photographs B and B 2 the coupling is still less 

 between the pendulums P and R. This is shown both in the 

 table and in the traces. For photograph B the pendulums 

 were started by drawing Q aside at Gr, and for B 2 by drawing 

 P aside at F. The trace of P in photograph B does not 

 indicate more than two simple harmonic vibrations, nor are 

 the traces in photograph B 2 very striking. 



For photograph 0, the coupling between the pendulums P 

 and R was considerably increased, but that between P and Q 

 was decreased. The resultant effect was to materially increase 

 all the couplings as P acted on Q by means of the connectors 

 DD' and CO', which were both tightly coupled. All these 

 traces can be seen to contain more than two simple harmonic 

 motions. 



For the photographs D to H inclusive the droop of the bridle 

 was increased. For traces shown on photographs D and E, the 

 couplings between all the pendulums due to the position of 

 the connectors were decreased, but this was compensated by 

 the increased droop. With P pulled aside (see D), the traces 

 from P and Q only appear to be the resultant of two simple 

 harmonic vibrations, but the beats in Rare slower on reaching 

 their maximum than in falling to their minimum. All the 

 traces with Q pushed aside (see E) show more complicated 

 curves. These could be obtained by compounding three 

 simple harmonic vibrations of the proper phase and 

 amplitude. 



Phil. Mag. S. G. Vol. 40. lNTo. 239. JSor. 1920. 2 S 



