Hacjkgtt — The Twist and Magnetisation of a Steel Tube. 419 



per second, giving the broken line shown. The position of this curve shows 

 that the process eliminates hysteresis, since it lies symmetrically in the 

 hysteresis loop. In fact, the process is so complete that it is a matter of 

 indifference in what order the observations are taken, or how the circular and 

 longitudinal fields are applied. The final reading is always the same. The 



15 



Pig. 1. 



previous magnetic history is completely wiped out. We conclude that the 

 axis of magnetization is by this process brought into coincidence with the 

 direction of the resultant field. 



Test of the theory. — This method of anhysterization gives us a means of 

 testing the above formula for the twist in the following manner : — A given 



