﻿On 
  Elliptic 
  Polarization, 
  195 
  

  

  when 
  the 
  photograph 
  was 
  taken, 
  the 
  waves 
  appearing 
  

   stationary. 
  An 
  exposure 
  of 
  ten 
  seconds 
  was 
  given. 
  

  

  I 
  have 
  recently 
  been 
  speculating 
  about 
  the 
  question 
  of 
  the 
  

   flow 
  of 
  energy 
  in 
  cases 
  where 
  interference-fringes 
  are 
  formed, 
  

   and 
  have 
  been 
  making 
  some 
  experiments 
  with 
  interfering 
  

   mercurv-ripples. 
  Some 
  trouble 
  was 
  experienced 
  from 
  the 
  

   reflexion 
  of 
  the 
  waves 
  from 
  the 
  sides 
  of 
  the 
  dish 
  as 
  well 
  as 
  

   from 
  waves 
  which 
  originated 
  at 
  the 
  sides 
  resulting 
  from 
  the 
  

   jar 
  communicated 
  to 
  the 
  table 
  by 
  the 
  tuning-fork. 
  I 
  found 
  

   that 
  both 
  sets 
  of 
  disturbances 
  could 
  be 
  prevented 
  by 
  pouring 
  

   glycerine 
  around 
  the 
  edge 
  of 
  the 
  dish 
  in 
  the 
  capillary 
  

   depression 
  formed 
  by 
  the 
  mercury. 
  The 
  viscous 
  fluid 
  sticks 
  

   to 
  the 
  edge 
  of 
  the 
  dish, 
  and 
  shows 
  little 
  tendency 
  to 
  spread 
  

   towards 
  the 
  centre, 
  even 
  if 
  used 
  in 
  considerable 
  quantities. 
  

   This 
  corresponds 
  to 
  painting 
  the 
  walls 
  of 
  the 
  room 
  black 
  

   when 
  making 
  optical 
  experiments. 
  

  

  In 
  the 
  case 
  of 
  interference-fringes 
  formed 
  by 
  two 
  sources 
  

   vibrating 
  with 
  equal 
  amplitudes, 
  the 
  flow 
  of 
  energy 
  is 
  along 
  

   the 
  hyperboloids 
  it 
  appears 
  to 
  me. 
  With 
  the 
  mercury 
  

   ripples 
  and 
  the 
  stroboscopic 
  fork, 
  we 
  can 
  see 
  the 
  waves 
  

   travelling 
  along 
  the 
  curved 
  hyperboloidal 
  paths. 
  So 
  far 
  as 
  

   I 
  know 
  the 
  question 
  of 
  energy-flow 
  in 
  the 
  case 
  of 
  interference 
  

   has 
  not 
  been 
  discussed 
  up 
  to 
  the 
  present 
  time, 
  and 
  there 
  are 
  

   some 
  interesting 
  points 
  in 
  connexion 
  with 
  it, 
  such 
  as 
  the 
  form 
  

   of 
  the 
  wave-front 
  which 
  travels 
  along 
  a 
  bright 
  fringe, 
  and 
  

   whether, 
  if 
  passed 
  through 
  a 
  slit 
  and 
  received 
  by 
  the 
  eye, 
  

   we 
  should 
  see 
  both 
  sources 
  resolved 
  or 
  not. 
  I 
  am 
  inclined 
  to 
  

   think 
  that 
  at 
  least 
  two 
  bright 
  fringes 
  would 
  have 
  to 
  be 
  trans- 
  

   mitted 
  for 
  resolution 
  to 
  take 
  place, 
  but 
  have 
  not 
  tried 
  the 
  

   experiment 
  yet. 
  These 
  matters 
  will 
  be 
  postponed 
  for 
  a 
  sub- 
  

   sequent 
  paper. 
  

  

  XXII. 
  On 
  tJie 
  Elliptic 
  Polarization 
  produced 
  hy 
  the 
  Direct 
  

   Transmission 
  of 
  a 
  Plane 
  Polarized 
  Stream 
  through 
  a 
  Plate 
  

   of 
  Quartz, 
  cut 
  in 
  a 
  Direction 
  oblique 
  to 
  the 
  Optic 
  Aa;is, 
  icith 
  

   a 
  Method 
  of 
  Determining 
  the 
  Error 
  of 
  a 
  Plate 
  supposed 
  to 
  

   he 
  Perjyendicular 
  to 
  the 
  A.vis. 
  By 
  James 
  Walker, 
  M.A.^ 
  

   O.vford 
  *. 
  

  

  1. 
  TT 
  ET 
  the 
  primitive 
  stream 
  with 
  polarization-vector 
  

   i 
  J 
  Exp 
  {mt) 
  be 
  polarized 
  in 
  an 
  azimuth 
  a. 
  with 
  respect 
  

  

  to 
  the 
  principal 
  section 
  of 
  the 
  quartz 
  plate. 
  This 
  may 
  be 
  

  

  replaced 
  by 
  the 
  elliptically 
  polarized 
  stream 
  represented 
  by 
  

  

  the 
  vector 
  

  

  (^1, 
  ^i) 
  = 
  Ci(cos 
  13, 
  - 
  1 
  sin 
  /S) 
  Exp 
  { 
  t(nt 
  + 
  ei) 
  } 
  , 
  

   * 
  Communicated 
  by 
  the 
  Physical 
  Society 
  : 
  read 
  November 
  27, 
  1908. 
  

  

  02 
  

  

  