Brown — Mechanical Stress and Magnetisation of Nickel. 35 



between 80 and 200 ; but only two are given here (not to crowd the figure) 

 wliich show a remarkable diminution in the internal viscosity of the wire, 

 due to tlie high fields. 



The curve given for the magnetic field of 200 units may be a little high, 

 due to the solenoid and wire becoming slightly heated during the experiment, 

 when an electric current of nearly 5 amperes was on for about four minutes. 



.200 



10 



20 30 40 



Fig. 2. — Number of Vibratious. 



50 



60 



70 



Tlie damping imposed on the torsional vibrations of the wire by a 

 magnetic field is better brought out by considering the amplitude attained 

 after a certain definite number of oscillations have been made. 



In Table III. are given the results obtained when four different 

 longitudinal loads were on the wire and when it was subjected to the action 

 of ten different longitudinal magnetic fields for each of the four loads. 



The numbers in the Table are the amplitudes of the oscillations attained 

 after 70 vibrations had been accomplished— in every case starting from an 



SOIENI. PBGC., K.D.S., VOL,. XIII., NO. III. ^ 



