[ 163 j 



XVII. 



THE FATIGUE OF NICKEL AND IKON WIRES WHEN SUBJECTED 

 TO THE INFLUENCE OF TEANSVEESE ALTEENATING 

 MAGNETIC FIELDS. 



By WILLIAM BEOWN, B.Sc, 

 Professor of Applied Physics, Eoyal College of Science for Ireland, Dublin. 



Read November 28, 1916. Published January 3, 1917. 



During the year November, 1914, to November, 1915, I brought before this 

 Society the results of some experiments on the fatigue of nickel and iron 

 wires when they were subjected to the influence of longitudinal alternating 

 magnetic fields of frequencies 50 to 250 cycles per second. 1 



The present communication gives the results of experiments on the 

 fatigue of nickel and iron wires when subjected to the influence of transverse 

 alternating magnetic fields of frequency 50 per second. 



The transverse magnetic fields for these experiments were obtained as 

 follows, referring to Fig. 1 : — 



I is an iron tube, with a slot 3 - 5 cms. wide cut down its whole length, 

 the tube being 226 cms. long, 64 cms. external diameter, and 5"1 cms. 

 internal diameter. The five copper wires C down the middle of the tube 

 were each 0"4 cms. in diameter, and were well insulated from each other, as 

 well as from the wooden support W, the circuit being so arranged that the 

 current went through the five wires in the same direction, and produced 

 a transverse alternating magnetic field across the gap of the iron tube. 



The relation between the current in the copper wires C and the magnetic 

 field in the gap of the iron tube was found in the usual way by means of an 

 exploring coil, earth inductor, and ballistic galvanometer. On plotting the 



1 Scient. Proc. Roy. Dubl. Soc. (1915), vol. xiv, No. 26, p. 336, No. 39, p. 521, and 

 vol. xv (1916), No. 1, p. 1. 



SCIENT. PEOC. K.D.S., VOL. XV., NO. XVII. 2 E 



