6 ART. 7. — K. HÜXDA AND T. ÏERADA. 



the torsion cylinder to ;:^ • of a degree. In the experiment ot 

 the tension effect, the above arrangement served to prevent any 

 accidental twisting of the S2:)ecimen ^vithout causing a sensible 

 friction to the stretchiuir. 



§ 2. IVIETHOD OF EXPERIIVIENTS. 



Our procedure was usually made in the following order : The 

 direct effect of the magnetizing coil on the galvanometer was 

 tested first of all. The specimen was removed, the secondary 

 circuit opened, and the maximum current was passed through the 

 primary. If there were aiiy constant deflection of the galvano- 

 meter mirror, the observer signalled to the exj)erimenter wlio 

 adjusted the orientation of the compensating primary coil, till the 

 deflection was brought to zero, in breaking, making or reversing 

 the current. 



Next the secondary circuit was closed, a strong current was 

 passed through the primary, while the observer w^as watching the 

 galvanometer ; the compensating secondary was slid within the 

 primary, till the ballistic deflection was reduced to zero. 



Next the compensation for the earth field was effected. For 

 this purpose, the specimen was introduced into the magnetizing 

 coil, clamped firmly and stretched by a suitable tension, care be- 

 ing paid to place the wire co-axially with the coils. The speci- 

 men was carefully demagnetized by reversals ; the secondary was 

 closed, a weak field excited in the primary, and the consequent 

 deflections noted. After a complete demagnetization, the came 

 magnetizing current was passed in the opposite direction. If the 

 two corresponding deflections of the galvanometer Avere not equal 

 to each other, the resistance in the compensating circuit was so 



