f 



CHANGE OF DIMENSIONS BY MAGNETIZATION, 



81 



5. The experiments on the change of length by circular 

 magnetization, namely, on the change of dimension in a direction 

 perpendicular to the magnetic field, were conducted in the 

 following manner. The tube was first demagnetized and a 

 circular magnetizing current was made only for a moment and 

 the corresponding deflection read. The change of length due 

 to magnetization followed almost instantaneously, but the change 

 due to the heating of the coil became sensible somewhat later; 

 hence these two effects were unmistakably distinguishable so 

 long as the magnetizing current was not strong. On this 

 account the highc.-t field did not exceed 100 C.G.S. units. 



The eßfect of the longitudinal field on the change of length 

 by circular magnetization was also measured. A constant longi- 

 tudinal field was first made and the corresponding deflection 

 observed ; then currents of different strength were momentarily 

 passed through the circular magnetizing coil, and the additional 

 deflection was read. These results are given in the following 

 table and also in Fig. 1 : 



TABLE 1. 



