﻿690 
  Prof. 
  0. 
  W. 
  Richardson 
  on 
  the 
  Kinetic 
  

  

  Columns 
  1 
  to 
  4 
  refer 
  to 
  a 
  set 
  of 
  readings 
  with 
  the 
  current 
  

   in 
  one 
  direction, 
  called 
  direct, 
  and 
  columns 
  5 
  and 
  6 
  to 
  a 
  set 
  

   in 
  the 
  opposite 
  direction. 
  Column 
  1 
  indicates 
  the 
  relative 
  

   displacement 
  o£ 
  the 
  slit 
  as 
  measured 
  on 
  the 
  screw-head. 
  

   Columns 
  2 
  and 
  5 
  give 
  the 
  readings 
  in 
  scale-divisions 
  due 
  to 
  

   the 
  thermionic 
  current 
  through 
  the 
  slit 
  in 
  30 
  seconds. 
  

   Column 
  3 
  gives 
  the 
  deflexion 
  of 
  the 
  electrometer 
  after 
  the 
  

   condenser 
  attached 
  to 
  the 
  plates 
  has 
  been 
  connected 
  with 
  the 
  

   electrometer. 
  The 
  numbers 
  are 
  therefore 
  proportional 
  to 
  

   the 
  charge 
  received 
  by 
  both 
  the 
  slit 
  and 
  the 
  plates 
  in 
  the 
  

   same 
  time-interval. 
  The 
  numbers 
  in 
  column 
  4 
  are 
  obtained 
  

   by 
  dividing 
  the 
  numbers 
  in 
  2 
  by 
  the 
  corresponding 
  numbers 
  

   in 
  3. 
  Column 
  6 
  gives 
  the 
  corresponding 
  quantities 
  for 
  the 
  

   experiment 
  with 
  the 
  current 
  reversed. 
  These 
  ratios 
  are 
  

   therefore 
  proportional 
  to 
  the 
  fraction 
  of 
  the 
  total 
  current 
  

   to 
  the 
  plates 
  which 
  passes 
  through 
  the 
  slit; 
  they 
  are 
  not 
  

   identical 
  with 
  this 
  on 
  account 
  of 
  the 
  capacities 
  being 
  different. 
  

   To 
  get 
  the 
  actual 
  fractions 
  it 
  is 
  necessary 
  to 
  multiply 
  the 
  

   values 
  given 
  by 
  the 
  ratio 
  of 
  the 
  two 
  capacities 
  used 
  in 
  the 
  

   two 
  cases. 
  In 
  these 
  experiments 
  this 
  multiplier 
  was 
  102/3102. 
  

  

  It 
  will 
  be 
  observed 
  that 
  the 
  values 
  in 
  column 
  6 
  are 
  

   throughout 
  somewhat 
  greater 
  than 
  those 
  in 
  column 
  4. 
  The 
  

   causes 
  of 
  this 
  want 
  of 
  symmetry 
  have 
  already 
  been 
  discussed. 
  

   To 
  eliminate 
  it 
  as 
  far 
  as 
  possible 
  the 
  mean 
  of 
  the 
  two 
  series 
  

   of 
  values 
  are 
  given 
  in 
  column 
  7^ 
  whilst 
  column 
  8 
  contains 
  the 
  

   values 
  of 
  I/Iq 
  calculated 
  from 
  formula 
  (1) 
  for 
  the 
  particular 
  

   value, 
  z 
  = 
  '04: 
  cm., 
  of 
  the 
  distance 
  between 
  the 
  strip 
  and 
  the 
  

   plates 
  which 
  occurred 
  in 
  these 
  experiments. 
  It 
  will 
  be 
  ob- 
  

   served 
  that 
  the 
  formula 
  does 
  not 
  involve 
  any 
  arbitrary 
  con- 
  

   stant 
  except 
  in 
  so 
  far 
  as 
  Iq, 
  the 
  value 
  of 
  the 
  ratio 
  of 
  the 
  two 
  

   currents 
  at 
  the 
  central 
  maximum, 
  may 
  be 
  regarded 
  as 
  such. 
  

   Thus 
  all 
  the 
  other 
  points 
  are 
  determined 
  as 
  soon 
  as 
  the 
  height 
  

   of 
  the 
  central 
  maximum 
  is 
  given. 
  The 
  agreement 
  between 
  

   columns 
  7 
  and 
  8 
  is 
  very 
  satisfactory 
  near 
  the 
  middle 
  of 
  the 
  

   table 
  when 
  the 
  values 
  of 
  the 
  ratio 
  are 
  considerable 
  ; 
  but 
  it 
  is 
  

   not 
  so 
  good 
  further 
  away 
  from 
  the 
  centre 
  where 
  the 
  ratios 
  are 
  

   small. 
  The 
  extent 
  of 
  the 
  agreement 
  can 
  be 
  gauged 
  better 
  

   when 
  the 
  results 
  are 
  exhibited 
  graphically; 
  and 
  it 
  is 
  con- 
  

   venient 
  to 
  postpone 
  further 
  discussion 
  of 
  the 
  results 
  until 
  that 
  

   has 
  been 
  done. 
  

  

  In 
  order 
  to 
  exhibit 
  the 
  results 
  graphically 
  it 
  is 
  convenient 
  

   to 
  multiply 
  each 
  series 
  of 
  ratios 
  by 
  a 
  common 
  factor, 
  so 
  that 
  

   they 
  all 
  have 
  the 
  same 
  maximum 
  point. 
  This 
  enables 
  us 
  to 
  

   test 
  the 
  assertion 
  made 
  above 
  that 
  the 
  differences 
  which 
  arise 
  

   when 
  the 
  current 
  is 
  reversed 
  disappear 
  when 
  relative 
  values 
  

   only 
  are 
  considered. 
  For 
  in 
  that 
  case 
  if 
  each 
  series 
  is 
  brought 
  

  

  