338 Mr. L. C. Jackson on 



Fig. 2 is a graph showing the relation between 7 and pjq. 











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20 25 30 35 



4-5 50 

 per cent 



55 



IV. Experimental Arrangements and Results. 



The apparatus used by the author consists of a gravity 

 pendulum coupled to an elastic pendulum, the motions of the 

 two being recorded photographically. Fig. 3 is a general 

 view of the arrangement. For the purpose of recording the 

 vibrations, each bob carries a small electric lamp and means 



