12 



Al;T. 13.— K. HONDA, S. SHIMIZU AND S. KUSAKABE 



Thu.s ill weak fields, the deflection shows ii farther twisting of 

 the nickel, that is, a decrease of rigidity. This decrease reaches a 

 maximum as the field becomes stronger ; it then begins to decrease, 

 and in a field of about 100 C.G.S. units, the rigidity returns toits 

 original value. When the field is farther increased, the rigidity 

 rapidly increases, and after passing an infiexion point, its rate of 

 increase becomes gradually less. Thus the character of the change is 

 quite analogous to that of the change of elasticity. 



In a iriven field, the amount of torsion or detorsion due to 

 magnetization is proportional to the applied couple, so that the 

 change of rigidity is independent of the C(3iiple for all magnetizing 

 fields. It is als») a proof of the fact that the curves corresponding to 

 different couj)les pass through a point on the axis of the field. The 

 ratio of the cliani>e t(j the modulus itself for different fields are "'iven 

 in the followinu' table and in Vvs. 2 : — 



