42 Prof. Barton and Miss Browning on Coupled 



four photographs (with couplings 1 per cent, to 28 per cent.)« 

 were obtained by drawing aside the heavy bob and allowing 

 the lighter one to settle in its more or less displaced position, 

 according as the coupling was tight or loose. The fifth (with 

 coupling 28 per cent.) was obtained by holding the light 

 bob in its undisplaced position and pulling the heavy one 

 aside. 



In all the curves it is noticeable that there is very little 

 fluctuation of the amplitude of the heavier bob, although the 

 amplitude of the lighter one waxes and wanes considerably. 

 Comparing fig. 1 of this paper with figs. 6 and 21 of the 

 January paper, it is seen that the amplitude of the lighter 

 bob in fig. 6, Paper II., is much greater than that attained 

 when the lengths are unequal as well as the masses. But the 

 shorter pendulum in fig. 21, Paper II., has an amplitude 

 much less than that of the shorter pendulum in the present 

 case. Pig. 4 in this paper is almost identical with fig. 8 of 

 Paper II., the amplitudes in the two cases are nearly the same 

 and the couplings are almost alike. Fig. 5 of this paper is 

 also similar to fig. 9 of Paper II. 



Masses 20 : 1, Lengths 9 : 8 (77 = 8 : 9).— Table II. shows 

 the frequencies for certain couplings with the masses of tho 

 bobs 20 : 1 and the lengths of the pendulums 9 : 8, the longer 

 one having the heavier bob and being 229 cm. long if the 

 droop of the bridle were zero. 



Table II.— Masses 20 : 1, Lengths 9 : 8. 



Coupling 

 -7- 



Per cent. 







4 

 10 



15-75 

 29-5 



Bridle Droop 



-=0 



Long Pendulum Length. 







019 

 055 

 1 



2-6 



Frequency 

 Ratio 



1-06 



1-162 



1-32 



1-494 



2 



Figs. 7-12 (PI. III.) show photographs taken with masses 

 still 20 : 1, but the length of the pendulum with the lighter 

 bob 8/9 that of the one with the heavier bob. Again we 

 see very little fluctuation of the amplitude of the heavy bob 

 throughout. Figs. 7-9 were taken with the heavy bob held 

 aside and the light one free to hang in its more or less dis- 

 placed position. Fig. 10 was taken with the light bob held 



