Brown — The Fatigue of Nickel and Iron Wires. 



167 



double the time to attain that maximum. The results are better seen in 

 Fig. 2 in the form of curves, where L and T indicate the curve showing 

 the effect of the longitudinal and transverse alternating magnetic fields 

 respectively. 



0-3 



<»02 



3 



O 



01 



L 



6 8 



Minutes 



10 



12 



Fig. 2. 



Section 2. 



It 



Win 



The wire tested was a No. 16 s.w.g. of simple rigidity 810 x 10" grammes 

 per sq. cm., the longitudinal load on the lower end being 10 5 grammes per 

 sq. cm. The magnetic field in the solenoid S corresponding to this load, 

 that is, to give the largest " Wiedemann effect," was 2"5 c.g.s. units, 1 and the 

 current through the wire under test one ampere. 



The experiment was the same as that performed on the nickel wire, and 

 the results obtained are given in Table II, where for comparison are also 

 given the results formerly obtained for the same wire with longitudinal 

 alternating magnetic fields of the same intensity as the transverse alternating 

 magnetic fields now used. 2 



1 Scient. Proc. Roy. Dubl. Soc, vol. xii (1910), No. 36, p. 484. 



2 Ibid., vol. xiv (1915), No, 26, p. 342. 



