﻿Experiment 
  relating 
  to 
  the 
  Drift 
  of 
  the 
  AUther. 
  11 
  

  

  a 
  reflected 
  train 
  (thick 
  broken 
  lines), 
  these, 
  after 
  reflexion 
  

   from 
  the 
  glass 
  plate, 
  produce 
  another 
  train 
  (thick 
  continuous 
  

   lines). 
  The 
  two 
  sets 
  of 
  waves, 
  represented 
  by 
  the 
  thin 
  and 
  

   thick 
  lines, 
  interfere 
  and 
  produce 
  the 
  fringes 
  whose 
  laws 
  we 
  

  

  

  have 
  to 
  investigate. 
  The 
  figure 
  gives 
  an 
  instantaneous 
  

   picture 
  of 
  the 
  configuration 
  of 
  the 
  waves 
  in 
  the 
  aether 
  for 
  

   a 
  special 
  case 
  of 
  motion 
  and 
  disposition 
  of 
  the 
  planes*. 
  The 
  

   diagram 
  is 
  complicated 
  by 
  the 
  number 
  of 
  lines. 
  But 
  the 
  

   different 
  trains 
  can 
  be 
  followed 
  easily, 
  and 
  afterwards 
  the 
  

   eye 
  fixed 
  on 
  the 
  continuous 
  lines 
  only. 
  The 
  essential 
  point 
  

  

  * 
  The 
  figure 
  is 
  drawn 
  to 
  scale 
  for 
  the 
  case 
  of 
  U 
  = 
  yV, 
  drift 
  makes 
  angle 
  

   •of 
  53° 
  8' 
  (tan 
  a=f) 
  with 
  OA. 
  CO,A=44° 
  30', 
  mirrors 
  at 
  90° 
  to 
  one 
  

   another. 
  

  

  