﻿Posit 
  ice 
  Electricity. 
  827 
  

  

  deflexion 
  we 
  are 
  measuriDg 
  become 
  neutralized 
  in 
  passing 
  

   througli 
  the 
  longer 
  field, 
  the 
  deflexion 
  produced 
  by 
  the 
  short 
  

   field 
  will 
  be 
  greater 
  than 
  that 
  by 
  the 
  long, 
  provided 
  the 
  

   length 
  of 
  })ath 
  of 
  the 
  particle 
  when 
  uncharged 
  is 
  comparable 
  

   with 
  the 
  length 
  of 
  the 
  shorter 
  field. 
  

  

  For 
  this 
  experiment, 
  chisel-shaped 
  pole-pieces 
  whose 
  ends 
  

   were 
  rectangular 
  were 
  used, 
  the 
  longer 
  side 
  of 
  the 
  rectangle 
  

   was 
  4*5 
  cm., 
  the 
  shorter 
  side 
  '7 
  cm. 
  The 
  distance 
  between 
  

   the 
  pole-pieces 
  was 
  6 
  mm. 
  The 
  poles 
  were 
  arranged 
  (1) 
  so 
  

   that 
  the 
  longer 
  side 
  of 
  the 
  rectangle 
  was 
  parallel 
  to 
  the 
  path 
  

   of 
  the 
  positive 
  particle, 
  so 
  that 
  this 
  was 
  exposed 
  to 
  a 
  

   magnetic 
  field 
  for 
  about 
  5 
  cms. 
  of 
  path, 
  and 
  (2) 
  with 
  the 
  

   shorter 
  side 
  parallel 
  to 
  the 
  path 
  so 
  that 
  the 
  particle 
  was 
  

   exposed 
  to 
  the 
  magnetic 
  field 
  for 
  less 
  than 
  a 
  centimetre 
  of 
  path. 
  

   The 
  currents 
  through 
  the 
  electromagnets 
  were 
  adjusted 
  so 
  

   that 
  the 
  deflexion 
  would 
  be 
  the 
  same 
  for 
  a 
  particle 
  which 
  

   retained 
  its 
  charge 
  the 
  whole 
  of 
  the 
  time 
  it 
  remained 
  in 
  either 
  

   field. 
  It 
  was 
  found 
  under 
  these 
  circumstances 
  that 
  when 
  the 
  

   pressure 
  was 
  too 
  high 
  to 
  give 
  well-defined 
  spots 
  the 
  deviations 
  

   of 
  the 
  tips 
  of 
  the 
  luminous 
  bands 
  into 
  which 
  the 
  phosphores- 
  

   cence 
  was 
  drawn 
  out 
  were 
  the 
  same 
  in 
  both 
  cases 
  ; 
  showing 
  

   that 
  the 
  maximum 
  value 
  of 
  ejm 
  got 
  by 
  this 
  method 
  is 
  the 
  

   ratio 
  of 
  the 
  charge 
  on 
  the 
  particle 
  to 
  its 
  mass, 
  and 
  not 
  the 
  

   average 
  extending 
  over 
  a 
  time 
  during 
  part 
  of 
  which 
  it 
  is 
  

   uncharged. 
  

  

  Though 
  the 
  maximum 
  deflexion 
  is 
  the 
  same 
  with 
  the 
  two 
  

   fields, 
  there 
  are 
  minor 
  differences 
  in 
  the 
  appearance 
  of 
  the 
  

   phosphorescent 
  patch 
  ; 
  with 
  the 
  short 
  field 
  the 
  portion 
  of 
  the 
  

   band 
  which 
  is 
  not 
  deflected 
  at 
  all 
  is 
  noticeably 
  brighter 
  than 
  

   in 
  the 
  longer 
  field. 
  This 
  is 
  what 
  we 
  should 
  expect 
  if 
  the 
  

   rays 
  contain 
  large 
  quantities 
  of 
  neutral 
  doublets 
  which 
  break 
  

   up 
  into 
  positively 
  and 
  negatively 
  electrified 
  parts 
  as 
  they 
  

   pass 
  through 
  the 
  tube 
  and 
  collide 
  against 
  the 
  molecules 
  of 
  the 
  

   residual 
  gas. 
  

  

  The 
  behaviour 
  of 
  the 
  portion 
  of 
  the 
  luminosity 
  due 
  to 
  

   negatively 
  charged 
  portions 
  of 
  the 
  Canalstrablen 
  is 
  interest- 
  

   ing 
  and 
  throws 
  light 
  on 
  their 
  origiu 
  ; 
  the 
  determination 
  of 
  

   ejin 
  for 
  these 
  shows 
  that 
  they 
  are 
  not 
  corpuscles 
  but 
  that 
  

   their 
  mass 
  is 
  much 
  the 
  s;ime 
  as 
  that 
  of 
  the 
  positive 
  particles, 
  

   they 
  are 
  in 
  fact 
  neutral 
  doublets 
  which 
  have 
  acquired 
  a 
  

   negative 
  charge. 
  

  

  The 
  brightness 
  of 
  the 
  negative 
  part 
  of 
  the 
  phosphorescence 
  

   depends 
  very 
  much 
  on 
  the 
  intensity 
  of 
  the 
  magnetic 
  field 
  ; 
  

   as 
  the 
  intensity 
  of 
  the 
  field 
  increases 
  these 
  negative 
  rays 
  at 
  a 
  

   certain 
  stage 
  increase 
  so 
  quickly 
  in 
  brightness 
  as 
  to 
  give 
  the 
  

   impression 
  that 
  they 
  suddenly 
  spring 
  into 
  existence. 
  Again, 
  

  

  