Brown — Mechanical Stress and Magnetisation of Nickel. 513 



three times (when hanging loosely in a vertical position with no load on it), 

 so as to make sure that it was as soft as the material and metliod of softening 

 wonld permit. 



The wires (226 cms. in length) were then put through the tests, with a 

 longitudinal load on the end of each equivalent to lO'^ grammes per sq. cm. — 

 that is, the twists were observed in the usual way when the wires were 

 successively subjected to sixteen different longitudinal magnetic fields, the 

 current through the wire in all cases being at the rate of 100 amperes per 

 square centimetre. 



The results obtained are given in Table VI. 



If we plot these results in Table VI in curves with the values of the 

 longitudinal magnetic fields as abscissae, and as ordinates the corresponding 

 values of the twist in each case, the curves will be found to be very 

 symmetrical and practically parallel to one another, the maximum twist in 



