TO B 



ronson- 



■Transverse Vibrations of Helical Springs. 



case of the rubber cord the contact was made by a very fine 

 wire bent as shown in fig. 8. 



The end a was firmly fastened. The point c was fastened 

 with rubber cement to the rubber cord, the vibration of which 

 caused the point d to dip into a mercury cup. The spring b 

 was used to increase the flexibility of the wire until it had 

 practical^ no period of vibration of its own. While there are 

 some objections to this method of making the contact, the 

 weight of the wire was so small and the adjustments made with 

 such care, that the results are sufficiently satisfactory for com- 



X 



•3o 











300 



-28 











280 



-26 











2S0 













240- 



-24 



»' / 









220- 

 2oo- 



l&O 



ISO 



-22 

 -20 



3 j 



5 P 



H 



0*7 



P l 9 



§1 





14c. 



■ IB 











120- 













100- 



-16 











80 













eo- 



14 











40- 



12 / y 











20. 













o 



ID 









L 



ZS 35 45 SS 6S TS &S 95 io5 liS 



parison with those of the springs. In all cases with the rubber 

 the successive observations were made as rapidly as possible, 

 in order that time effects might be reduced to a minimum. 

 Between the length-frequency observations and the length- 

 tension observations time was allowed to elapse until the rub- 

 ber practically recovered its original length. 



The tube and the cord gave very similar results ; those for 

 the cord are given in Table IX and fig. 9. 



