C. Barns — Apparent Hysteresis. 



99 



In figure 1 for example (to begin with the circular fields) a 

 nickel wire (L = 41, D = -05, C = 4) is twisted +45° and 

 —45° alternately, as shown by the abscissas. The deflections 

 observed are given by the ordinates in the order shown by the 

 arrows. The two observations recorded at each twist corre- 

 spond respectively to the first and the second (or succeeding) 

 magnetizations. The deflection of the former is always the 

 larger. The initial deflections or changes of rigidity due to 

 circular magnetization lie along a line, a, the succeeding deflec- 

 tions along a line, b, of smaller slope. The fiducial zero in 

 the successive twists suffers displacements due to the circular 

 magnetization alone and would be represented by a zigzag line 

 .as will be more definitely instanced below. 



If the deflections are studied between three successive twists 

 the result is even more striking as seen for example in figure 2, 

 for twists successively 0°, -45°, 0°, +45°, 0°. The lines for 

 initial and final deflections might again be drawn but they 

 would confuse the figure. The displacement of the zero is 

 such as to indicate two successive displacements in the same 

 direction. 



The phenomena are independent of the direction of the cur- 

 rent and a larger angle of twist does not magnify them in an 

 easily discernable way. 



The nickel wire being relatively thick and the current 

 closed but a short time, no attention was paid to the heat pro- 

 duced in the wire by the current. In the following experi- 



