Brown — Subsidence of Torsional Oscillations of Nickel Wires. 105 



300 



200 



CQ 



fa 

 o 



H 



a 



B 



H 



a 



25 SO 



Number of Vibrations. 



75 



When the hard nickel wire was tested in a transverse alternating 

 magnetic field of 65 units at frequencies 25, 50, 100, and 200 per second, the 

 numbers obtained in each of the four cases were precisely the same as those 

 in the column marked D. C. in Table III.— that is, alternating magnetic fields 

 with the above frequencies and of value 65 units have no effect on the damping 

 of the torsional oscillations of a hard nickel wire. This, of course, may not be 

 true when stronger magnetic fields are applied, which will be subsequently 

 tested when the apparatus now being prepared is in operation. The diminution 

 of the amplitude of the 70th vibration by about 10| per cent, with a transverse 

 alternating magnetic field of 200 units and frequency 50 per second, when 

 the nickel wire is soft, may be partly due to eddy currents set up in the wire 

 itself. In order to test this, a non-magnetic soft No. 16 copper wire was 



