Brown — Subsidence of Torsional Oscillations of Nickel Wires. 103 



comparison, the results for no field, or a direct field of 200 units are also 

 given in column marked (D.C). 



Table II. 



Eigidity =? 708 x 10" grammes per sq. cm. 



From the values in Table II it will be seen that there is slightly less 

 damping of the torsional oscillations when the frequency of the magnetic field 

 is increased ; thus, when the frequency is increased eight times, the amplitude 

 of the 70th vibration is increased about 4| per cent. 



The soft nickel wire was then taken down from the apparatus, and a hard 

 nickel wire put in its place. This new wire had a rigidity of about 

 810 x 10 6 grammes per sq. cm., and it was put through exactly the same series 

 of tests as the soft wire. In this case also it was found that the torsional 

 subsidence curves were identical for all direct transverse magnetic fields 

 from to 200 c.g.s. units ; and that when an alternating transverse magnetic 

 field of 200 units and frequency 50 per second was round the wire, the 

 damping curve was below the curve obtained with the direct field. The results 

 are given in Table III, and the values — not given — which were obtained with 

 alternating magnetic fields up to 150 units were intermediate between the 

 values given in the columns marked D.C. and A.C. in the table. 



