﻿Experiment 
  relating 
  to 
  the 
  Drift 
  oj 
  the 
  Mtlier. 
  25 
  

  

  Hence 
  

   D 
  1 
  D 
  2 
  sin^±^ 
  = 
  V 
  4 
  sm( 
  % 
  + 
  ^) 
  + 
  V 
  3 
  {-2 
  M 
  ;sin 
  (0- 
  x 
  ) 
  -v 
  cos 
  (2^ 
  — 
  X 
  )J 
  

  

  -h 
  V 
  2 
  { 
  — 
  2 
  1? 
  w 
  sin 
  sin 
  (% 
  + 
  0) 
  — 
  2ww' 
  sin 
  (</> 
  + 
  0) 
  

  

  — 
  W 
  cos 
  (2</> 
  -f- 
  0) 
  + 
  i<? 
  2 
  sin 
  (^ 
  + 
  0)} 
  

   + 
  Vrw 
  2 
  cos 
  ^ 
  + 
  vm! 
  2 
  w' 
  cos 
  ; 
  

  

  D 
  1 
  D 
  2 
  cos-"^2=V 
  4 
  cos( 
  % 
  + 
  6>) 
  + 
  V 
  3 
  {t^-vsin(2<^- 
  x 
  )} 
  

  

  + 
  V 
  2 
  {2m« 
  cos 
  <£ 
  sin 
  (^ 
  + 
  0)— 
  Wsin 
  (2c/> 
  + 
  0) 
  

  

  — 
  w 
  2 
  cos 
  (% 
  + 
  0) 
  } 
  

   -f 
  V{m- 
  2 
  sin 
  ^-m/w 
  2 
  }-to 
  2 
  «;' 
  sin 
  0. 
  

  

  From 
  these 
  it 
  can 
  be 
  shown, 
  after 
  easy 
  reduction, 
  that 
  

  

  ^^ 
  J 
  v 
  A 
  + 
  B^ 
  A-Bl 
  

   DiD 
  2 
  K 
  V 
  cos 
  — 
  y 
  — 
  hvcos 
  — 
  x— 
  > 
  

  

  = 
  (V 
  2 
  -t; 
  2 
  )(V 
  2 
  -«j 
  2 
  ){Vcos(x 
  + 
  0)Hr^} 
  

  

  = 
  (V 
  2 
  -v 
  2 
  )(V 
  2 
  -w 
  2 
  ){(Ycos0-w) 
  cosx-(Vsin0-?O 
  sin^} 
  

  

  ^^ 
  f_ 
  . 
  A 
  + 
  B 
  A-Bl 
  

  

  DjJ 
  2 
  \ 
  Vsm 
  — 
  » 
  it 
  cos 
  — 
  7 
  — 
  > 
  

  

  = 
  (V 
  2 
  — 
  w 
  2 
  )[(Vcos0— 
  u){(V 
  2 
  — 
  v 
  2 
  ) 
  sin 
  % 
  + 
  2uv 
  cos 
  %} 
  

  

  + 
  (Vsin0-r) 
  (V 
  2 
  -w 
  2 
  )cos 
  X 
  ]. 
  

  

  Hence 
  

  

  tgn^- 
  ( 
  y2 
  -^ 
  2 
  )U^cos0-^)cosx-(Ysin0-i;) 
  sin%} 
  / 
  17) 
  

   (Vcos 
  6 
  — 
  u){(Y' 
  2 
  —v 
  2 
  ) 
  sin% 
  + 
  2wi'Cos%j- 
  

  

  + 
  (V 
  sin 
  6 
  — 
  v) 
  (V 
  2 
  — 
  u 
  2 
  ) 
  cos 
  x 
  

  

  When 
  the 
  source 
  is 
  fixed 
  to 
  the 
  apparatus 
  (Vsin0 
  = 
  v), 
  

  

  . 
  , 
  2uv 
  

  

  cot-f=tan%+^2— 
  ^ 
  

  

  That 
  is, 
  if 
  the 
  ratio 
  U/V 
  is 
  very 
  small, 
  

  

  so 
  that 
  the 
  maximals 
  make 
  for 
  all 
  directions 
  of 
  drift 
  the 
  same 
  

   angle 
  with 
  the 
  first 
  mirror 
  as 
  the 
  second 
  does, 
  but 
  oppositely 
  

   inclined. 
  

  

  12. 
  Position 
  of 
  Central 
  Maximal. 
  — 
  Let 
  the 
  central 
  maximal 
  

  

  