32 



Prof. Barton and Miss Browning on 

 V. Experimental Results. 



Thirty-six photographic reproductions are given, each 

 showing the triple sand traces from the bohs P, Q, and P. 

 Each such trace exhibits the resultant vibration of two or 

 three components executed by the bob in question. 



Plate I. fig. 1 shows six sets of traces, each bearing a dis- 

 tinguishing letter, the details of the corresponding pendulum 

 lengths being given in Table I. For all these the bob P is 

 pulled aside, and the experimental results confirm the theory 

 that only two vibration components are present. The last 

 trace j3 shows clearly that either the quickest or the 

 slowest component is absent, since their frequency ratio 

 would be about 2:1. Theory shows it is the quickest that 

 is absent. 



Table I. 



; = 138 cms 



Trace. 



b. 

 134 cms. 



134 „ 



134 „ 



130 „ 



116 „ 



78 „ 



130 cms. 

 124 „ 

 116 ,. 

 116 „ 

 105 „ 

 34 „ 



Total 

 Bridle Length. 



)■ 200 ci 



; 



292 



Plate I. fig. 2 shows twelve sets of triple traces, the pendu- 

 lum lengths concerned being given in Table II. In all these 

 the bob Q is started, and here, again, the theory is confirmed 



Table II. 



a = 138 cms. 



Trace. 



b, 



O 134cms. 



134 



134 

 134 

 134 

 130 

 130 

 130 

 124 

 124 

 116 

 116 



c. 

 134 



130 



124 



116 



105 



124 



116 



105 



116 



105 



111 



105 



