Bkown — The Subsidence of Torsional Oscillations. 



133 



Table VI. 

 Rigidity =? 780 x 10 6 grammes per sq. cm. 

 H = 65 units. 



By comparing the values in Table VI, above, with those in Table II, 

 page 128, in the former paper, 1 it will be seen that, unlike nickel wire, the 

 damping of torsional oscillations in iron wire is slightly increased as the 

 frequency is increased. When the frequency is increased eight times, the 

 amplitude of the 70th oscillation is decreased about 4 per cent., whereas with 

 nickel wire tested under similar conditions the amplitude of the 70th oscilla- 

 tion is increased 4| per cent. 



The iron wire was then tested when of length 75 cms. with the oscillating 

 load on the end of the wire equal to 2 x 10 5 grammes per sq. cm. and a weight 

 of 2670 grammes on the scale-pan end of the silk string, the transverse 

 magnetic fields used being up to a maximum of 800 units both direct and 

 alternating. 



The more important of the values obtained are given in Table VII, and 

 those values — not given in the table — which were obtained with direct trans- 

 verse magnetic fields of strengths from 100 to 700 units were intermediate 

 to the values given in columns 2 and 3 in Table VII. 



1 Loc. tit. 



103. 



SCIENT. PROC. R.D.S., VOL. XV., NO. XIII. 



