Bkown — Mechanical Stress and Magnetisation of Nickel. 515 



Table VII. 



If the results given in Table VII be plotted with the values of the 

 longitudinal magnetic fields as abscissse, and as ordiiiates the corresponding 

 values of the twists, the three curves show that the maximum twist occurs in 

 the same longitudinal magnetic field of about 13 units in each case. By 

 plotting as abscissse the values of the current densities in the wire, and as 

 ordinates the corresponding values of the twists for any longitudinal 

 magnetic field, the points in every case will lie very approximately in a straight 

 line, which, when produced, passes through the origin, which again shows 

 that the twist is directly proportional to the current density in the wire. 



Some differences in the behaviour of iron and nickel when subjected to 

 simultaneous longitudinal and circular magnetism are shown in fig. 6 (p. 516), 

 where one of the curves should be drawn below the axis of the abscissa to 

 indicate that iron and nickel twist in opposite directions, but both are here 

 shown ahove the axis for convenience of reference, 



4d 



SCIENT. PKOC. K.D.S., VOL. XII., NO. XXXVII. 



