Brown — The Subsidence of Torsional Oscillations. 7 



Section II. 



It has already been shown in the torsional subsidence of iron wires that 

 the difference in the amplitudes of the 70th vih'ation,\?hen the wire is under the 

 influence of a direct longitudinal magnetic field, and when under the influence 

 of an alternating magnetic field of frequency 50 per second, diminishes as the 

 load increases, and that at a certain load this difference vanishes. 1 In order 

 therefore, to ascertain if this principle held with higher frequency alternating 

 magnetic fields, a new wire was taken from the same batch, and tested when 

 it was hard and when it was fairly soft. The experiments made were 

 identical with those described above : the wire was tested when it was 

 subjected to six different longitudinal loads and when under the influence of 

 a direct magnetic field, as well as under that of alternating magnetic fields 

 of frequency 50 and 250 per second, the field strength in each case being 

 2*8 c.g.s. units. 



A few of the results obtained with the wire in the hard state are given in 

 Table VIII, and in Table IX are recorded more detailed observations obtained 

 when the wire was in the soft state, that is, in the latter case there are 

 sufficient values given so that one may draw the curves if required. 



Table VIII. 

 Eigidity = 812 x 10° grammes per sq. cm. 



1 Scient. Proc. Roy. Dub. Soc, 1915, vol. xiv, No. 32, p. 398. 



