﻿352 
  

  

  Prof. 
  A. 
  A. 
  Michelson 
  on 
  

  

  and 
  4. 
  Those 
  marked 
  A 
  referring 
  to 
  observations 
  made 
  with 
  

   the 
  line 
  of 
  sight 
  at 
  right 
  angles 
  with 
  the 
  magnetic 
  field 
  and 
  

   with 
  the 
  plane 
  of 
  polarization 
  perpendicular 
  to 
  the 
  lines 
  of 
  

   force 
  ; 
  while 
  B 
  correspond 
  to 
  observations 
  with 
  the 
  line 
  of 
  

   sight 
  still 
  normal 
  to 
  the 
  field, 
  but 
  plane 
  of 
  polarization 
  

   parallel 
  with 
  the 
  lines 
  of 
  force. 
  

  

  Fig. 
  2.— 
  Type 
  I. 
  

  

  It 
  was 
  found 
  that 
  there 
  was 
  no 
  appreciable 
  difference 
  

   between 
  these 
  last 
  and 
  the 
  observations 
  taken 
  when 
  the 
  line 
  

   of 
  sight 
  was 
  parallel 
  with 
  the 
  field 
  ; 
  but 
  in 
  this 
  case 
  it 
  was 
  

   possible 
  to 
  analyse 
  either 
  one 
  of 
  the 
  outer 
  groups 
  separately 
  

   by 
  the 
  use 
  of 
  the 
  quarter-wave 
  plate, 
  Q, 
  fig. 
  1. 
  This 
  was 
  

   done 
  in 
  a 
  few 
  cases, 
  but 
  no 
  new 
  result 
  was 
  obtained. 
  

  

  The 
  abscissae 
  of 
  the 
  visibility-curves 
  are 
  differences 
  of 
  path 
  

   in 
  millimetres, 
  reduced 
  to 
  a 
  field-strength 
  of 
  10,000 
  as 
  

   determined 
  by 
  a 
  bismuth 
  spiral. 
  

  

  