396 



Scientific Proceedings, Royal Dublin Society. 



Table II. 

 Rigidity = 790 x 10" grammes per sq. cm. 



The fuU-liue curves are those for soft iron in a magnetic field of 2 '8 units, 

 and the broken-line curves are those for soft nickel wire in a magnetic field 

 of 17 units, the load on each being lO'^ grammes per sq. centimetre. 



From the tables and curves it will be seen that for iron wires, both in the 

 hard and soft states, the damping curves or curves showing the subsidence of 

 torsional oscillations obtained with the alternating magnetic fields all lie 

 below the curves obtained with the direct longitudinal magnetic fields; 

 whereas in alternating magnetic fields the curves got with hard nickel wire 

 lie below, and those obtained with soft nickel wire lie above the corresponding 

 curves got with direct longitudinal magnetic fields.' 



On examining the figures in Table II obtained with the two loads 1 x 10' 

 and 2 x 10% it will be noticed that the difference in the amplitude of oscillation 

 between the D.C. and A.C. values after 70 vibrations have taken place, 

 decreases as the load increases ; also, the final amplitude is decreased in the 

 D.C. and increased in the A.C. set of observations for increased load. 



' Solent. Proc. Eoy. Dub. Soc, vol. xiv, 1914, No. 14, pp. 218-221. 



