﻿436 
  

  

  Mr. 
  A. 
  P. 
  Wills 
  on 
  the 
  Susceptibility 
  of 
  

  

  The 
  bevelled 
  faces 
  are 
  on 
  angles 
  of 
  60 
  degrees. 
  When 
  in 
  

   position 
  the 
  pole 
  faces 
  are 
  parallel, 
  and 
  the 
  gap 
  between 
  

   them 
  is 
  about 
  1*5 
  centim. 
  The 
  figures 
  given 
  on 
  the 
  diagram 
  

  

  represent 
  centimetres. 
  

  

  Fig. 
  4. 
  

  

  > 
  

  

  