﻿692 
  Dr. 
  W. 
  F. 
  G. 
  Swann 
  on 
  a 
  Case 
  of 
  

  

  angle 
  between 
  and 
  + 
  d0 
  with 
  the 
  direction 
  o£ 
  the 
  field 
  

   is 
  given 
  by 
  

  

  3Xed 
  

  

  dn 
  = 
  6 
  mc 
  ' 
  zC0S 
  sin 
  Odd, 
  

  

  where 
  e 
  is 
  the 
  electronic 
  charge, 
  d 
  is 
  the 
  distance 
  between 
  

   the 
  constituents 
  of 
  a 
  doublet, 
  X 
  is 
  the 
  field, 
  and 
  c 
  2 
  is 
  the 
  

   mean 
  value 
  o£ 
  the 
  square 
  of 
  the 
  velocity 
  of 
  the 
  molecule, 
  

   the 
  average 
  value 
  of 
  cos 
  is 
  given 
  by 
  cos 
  6 
  where 
  

  

  /» 
  3Xed 
  r 
  3Xed 
  

  

  ■ 
  I 
  n 
  5- 
  COS 
  9 
  I 
  IT 
  7T 
  cos 
  9 
  „ 
  

  

  cos 
  e\ 
  € 
  m 
  ° 
  2 
  sin 
  0d0=\ 
  e 
  mc2 
  cos 
  . 
  sin 
  d0. 
  

  

  Jo 
  Jo 
  

  

  When 
  — 
  5- 
  is 
  very 
  small, 
  cos 
  reduces 
  to 
  =- 
  , 
  and 
  the 
  

  

  mc* 
  J 
  mc 
  1 
  _ 
  , 
  

  

  usual 
  view 
  taken 
  is 
  that 
  the 
  effect 
  is 
  the 
  same 
  as 
  if 
  — 
  5- 
  

  

  mc 
  z 
  

  

  doublets 
  emitted 
  a 
  corpuscle 
  p 
  times 
  per 
  second 
  in 
  the 
  

  

  direction 
  of 
  the 
  field, 
  where 
  p 
  is 
  the 
  number 
  of 
  corpuscles 
  

  

  emitted 
  by 
  an 
  atom 
  per 
  second 
  without 
  regard 
  to 
  direction. 
  

  

  Denoting 
  p 
  by 
  r, 
  if 
  squares, 
  and 
  cubes 
  of 
  r 
  are 
  not 
  

  

  mc 
  e 
  r 
  + 
  e~ 
  r 
  1 
  

   negligible, 
  cos 
  comes 
  out 
  as 
  — 
  - 
  r 
  , 
  which 
  reduces 
  to 
  

  

  tj( 
  r— 
  rj^i. 
  . 
  .). 
  In 
  our 
  experiments, 
  however, 
  r 
  is 
  only 
  

  

  of 
  the 
  order 
  0*01, 
  so 
  that 
  the 
  second 
  term 
  is 
  quite 
  inappreciable 
  

   compared 
  with 
  the 
  first. 
  If 
  this 
  had 
  not 
  been 
  so, 
  the 
  theory 
  

   would 
  have 
  predicted 
  an 
  effect 
  in 
  our 
  experiments 
  the 
  

   reverse 
  of 
  that 
  which 
  was 
  found 
  ; 
  i. 
  e., 
  when 
  the 
  plate 
  was 
  

   charged 
  positively 
  the 
  plate 
  A 
  would 
  have 
  shown 
  a 
  fall 
  of 
  

   potential 
  with 
  time 
  as 
  the 
  electricity 
  passed 
  across, 
  for 
  it 
  

   will 
  be 
  remembered 
  that 
  the 
  apparatus 
  does 
  not 
  detect 
  the 
  

   part 
  of 
  the 
  current 
  which 
  obeys 
  Ohm's 
  law. 
  Thus 
  the 
  above 
  

   simple 
  form 
  of 
  the 
  theory 
  does 
  not 
  give 
  any 
  suggestion 
  of 
  a 
  

   departure 
  from 
  Ohm's 
  law 
  for 
  the 
  fields 
  used. 
  It 
  must 
  be 
  

   admitted, 
  however, 
  that 
  the 
  application 
  of 
  the 
  Boltzmann 
  law 
  

   in 
  the 
  above 
  form 
  to 
  the 
  present 
  problem 
  is 
  a 
  very 
  bold 
  one, 
  for 
  

   in 
  view 
  of 
  the 
  close 
  proximity 
  of 
  the 
  atoms, 
  the 
  internal 
  coor- 
  

   dinates 
  must 
  play 
  an 
  important 
  part. 
  Further, 
  the 
  potential 
  

   energy 
  of 
  the 
  system 
  must 
  depend 
  not 
  only 
  on 
  the 
  orientation 
  

   of 
  the 
  doublets 
  with 
  respect 
  to 
  the 
  field, 
  but 
  largely 
  on 
  their 
  

   orientation 
  with 
  respect 
  to 
  each 
  other. 
  In 
  fact, 
  it 
  would 
  

   seem 
  that 
  we 
  might 
  be 
  nearer 
  the 
  truth 
  if 
  we 
  were 
  to 
  assume 
  

   that 
  the 
  orientation 
  of 
  the 
  molecular 
  doublets 
  followed 
  a 
  law, 
  

   analogous 
  in 
  its 
  relation 
  to 
  the 
  field, 
  to 
  the 
  law 
  followed 
  by 
  

   the 
  molecular 
  magnets 
  which 
  represent 
  the 
  atoms 
  of 
  a 
  piece 
  

   of 
  iron, 
  when 
  the 
  iron 
  is 
  subjected 
  to 
  a 
  magnetizing 
  field. 
  

  

  