﻿Experiment 
  relating 
  to 
  the 
  Drip 
  of 
  the 
  JEther, 
  27 
  

  

  obtained, 
  and 
  dividing 
  out, 
  

  

  xY{ 
  V 
  cos 
  ( 
  x 
  + 
  0) 
  + 
  w' 
  } 
  Q 
  = 
  a 
  { 
  D 
  2 
  2 
  cos 
  (<£ 
  + 
  B 
  ) 
  

  

  + 
  (Y 
  2 
  -itf 
  2 
  )(Y 
  2 
  -W 
  2 
  )sin 
  (6 
  + 
  0)}. 
  

  

  Bi 
  

   From 
  the 
  value 
  of 
  £ 
  2 
  in 
  § 
  8 
  it 
  easily 
  follows 
  that 
  

  

  + 
  V 
  2 
  j 
  -W 
  [I 
  +x 
  + 
  fl] 
  -2W 
  [| 
  -x-0] 
  

   + 
  ^ 
  |J 
  - 
  £-fl] 
  + 
  u- 
  2 
  [J 
  +^-2 
  x 
  -0] 
  j 
  

   + 
  V 
  I 
  _ 
  2 
  W 
  2 
  [Tj 
  + 
  2wV 
  [ 
  \ 
  + 
  <J> 
  -x] 
  j 
  + 
  ieV 
  2 
  [J 
  + 
  </> 
  + 
  0] 
  ; 
  

  

  whence 
  after 
  a 
  short 
  reduction, 
  

  

  D 
  2 
  2 
  cos 
  (0 
  + 
  B) 
  + 
  (Y 
  2 
  -w 
  2 
  ) 
  (V 
  2 
  — 
  k/ 
  2 
  ) 
  sin 
  (0 
  + 
  0) 
  

  

  = 
  2Y(Y 
  2 
  -™ 
  2 
  ){Ycos 
  (% 
  + 
  0) 
  +«/} 
  sin 
  fa-*'- 
  

   Therefore 
  

  

  Y 
  2 
  — 
  w 
  2 
  

  

  ^2a^-^sin(tf>- 
  X 
  ) 
  (18) 
  

  

  Since 
  this 
  is 
  independent 
  of 
  0, 
  the 
  position 
  of 
  the 
  central 
  

   "point 
  is 
  the 
  same 
  whether 
  the 
  source 
  is 
  fixed 
  in 
  the 
  cether 
  or 
  to 
  

   the 
  apparatus. 
  

  

  13. 
  We 
  have 
  now 
  obtained 
  the 
  magnitudes 
  of 
  the 
  various 
  

   quantities 
  required 
  for 
  the 
  discussion 
  of 
  the 
  experiment. 
  For 
  

   this 
  purpose, 
  however, 
  it 
  will 
  be 
  convenient 
  to 
  express 
  them 
  

   in 
  terms 
  of 
  quantities 
  defining 
  the 
  configuration 
  of 
  the 
  

   apparatus. 
  Let 
  C 
  denote 
  the 
  angle 
  between 
  the 
  two 
  mirrors, 
  

   and 
  let 
  A, 
  B 
  denote 
  the 
  angles 
  which 
  the 
  first 
  and 
  second 
  

   mirrors 
  respectively 
  make 
  with 
  the 
  plate. 
  Then 
  

  

  c=i*— 
  %, 
  

  

  Further, 
  denote 
  the 
  distance 
  of 
  0! 
  from 
  the 
  plane 
  of 
  the 
  

   second 
  mirror 
  by 
  b. 
  Then 
  

  

  b 
  = 
  a 
  sinB 
  = 
  « 
  sin 
  v<£~x)- 
  

  

  