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IX. 



THE SUBSIDENCE OF TORSIONAL OSCILLATIONS OF NICKEL 

 WIRES WHEN SUBJECTED TO THE INFLUENCE OF TRANS- 

 VERSE MAGNETIC FIELDS UP TO 200 C.G.S. UNITS. 



By WILLIAM BROWN, B.Sc. 

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



[Read February 22. Published April 3, 1916.] 



For some considerable time past I have, on various occasions, brought 

 before this Society the results of experiments on the behaviour of iron and 

 nickel wires when they were subjected to the influence of longitudinal 

 magnetic fields, both continuous and alternating. 



The present communication contains the results of some preliminary 

 experiments with nickel wires when they were subjected to the influence of 

 transverse magnetic fields. The transverse magnetic fields employed in the 

 experiments were produced in a soft iron tube 220 cms. long, 2 - 54 cms. 

 external diameter, and 1/6 cms. internal diameter, with a slot 0"5 cm. wide 

 cut right through the wall over the whole length of the tube, the faces of 

 the slot being 047 cm. wide. A bare copper wire 04 cm. diameter, painted 

 with insulating varnish, was fixed in the central axis of the iron tube by 

 means of a vulcanite bush at each end, and in order to keep the wire central 

 throughout the length of the tube, thin vulcanite discs were placed at 

 intervals. When an electric current is sent through the copper wire, a 

 transverse magnetic field is produced in the slot; and when a nickel wire 

 is placed in the slot, it will be subjected to the action of the transverse field, 

 that is, to a steady continuous magnetic field or to an alternating magnetic 

 field according as a direct current or an alternating current is sent through 

 the copper wire. 



The relation between the strength of the transverse magnetic field in the 



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



