﻿664 
  

  

  Prof. 
  J. 
  J. 
  Thomson 
  

  

  the 
  cathode. 
  It 
  was 
  found 
  that 
  the 
  structure 
  of 
  the 
  Canal- 
  

   strahlen 
  was 
  more 
  complicated 
  than 
  that 
  of 
  the 
  retrograde 
  

   positive 
  rays, 
  the 
  former 
  showing 
  two 
  types 
  of 
  rays, 
  charac- 
  

   terized 
  by 
  values 
  of 
  e/m 
  in 
  the 
  ratio 
  of 
  2 
  to 
  1 
  : 
  the 
  latter 
  

   showed 
  only 
  one 
  type 
  of 
  ray, 
  this 
  type 
  coinciding, 
  however, 
  

   both 
  as 
  to 
  value 
  of 
  e/m 
  and 
  the 
  velocity 
  with 
  the 
  type 
  of 
  

   Canalstrahlen 
  rays 
  having 
  the 
  maximum 
  value 
  of 
  e/m. 
  

   Some 
  of 
  the 
  retrograde 
  rays, 
  as 
  well 
  as 
  some 
  of 
  the 
  Canal- 
  

   strahlen, 
  are 
  deflected 
  in 
  a 
  direction 
  which 
  shows 
  that 
  they 
  

   carry 
  a 
  negative 
  charge, 
  and 
  that 
  their 
  mass 
  is 
  comparable 
  

   with 
  that 
  of 
  the 
  positively 
  charged 
  particles. 
  I 
  have 
  deter- 
  

   mined 
  the 
  value 
  of 
  e/m 
  and 
  the 
  velocity 
  of 
  these 
  negative 
  

   constituents 
  of 
  the 
  retrograde 
  rays, 
  and 
  find 
  that 
  the 
  value 
  

   of 
  e/m 
  for 
  the 
  negative 
  particles 
  is 
  numerically 
  equal 
  to 
  

   that 
  of 
  e/m 
  for 
  the 
  positive 
  ones 
  ; 
  while 
  the 
  velocity 
  of 
  the 
  

   negative 
  ones 
  is 
  slightly, 
  but 
  only 
  slightly 
  (about 
  15 
  per 
  

   cent, 
  in 
  my 
  experiments), 
  less 
  than 
  that 
  of 
  the 
  positive 
  ones. 
  

  

  Experiments 
  with 
  Goldstein 
  7 
  s 
  Double 
  Cathodes, 
  

  

  Goldstein 
  (loc. 
  cit.) 
  found 
  that 
  when 
  the 
  cathode 
  consists 
  

   of 
  two 
  parallel 
  plates 
  in 
  metallic 
  connexion, 
  rays 
  other 
  than 
  

   the 
  cathode 
  rays 
  proceed 
  from 
  the 
  space 
  between 
  the 
  plates. 
  

   If 
  the 
  plates 
  are 
  triangles, 
  Goldstein 
  found 
  that 
  a 
  pencil 
  of 
  

   easily 
  deflected 
  cathode 
  rays 
  start 
  from 
  the 
  middle 
  points 
  

  

  Fig. 
  3. 
  

  

  of 
  the 
  sides, 
  while 
  pencils 
  of 
  undeflected 
  rays 
  start 
  from 
  the 
  

   corners 
  of 
  the 
  triangle. 
  The 
  difference 
  in 
  the 
  character 
  of 
  

   the 
  rays 
  can 
  be 
  strikingly 
  shown 
  by 
  using 
  helium 
  in 
  the 
  

   discharge-tube, 
  when 
  the 
  rays 
  from 
  the 
  corners 
  are 
  red 
  and 
  

   those 
  from 
  the 
  sides 
  blue. 
  I 
  have 
  examined 
  the 
  electric 
  and 
  

   magnetic 
  deflexion 
  of 
  these 
  rays, 
  using 
  for 
  the 
  purpose 
  a 
  

   tube 
  such 
  as 
  that 
  showm 
  in 
  fig. 
  3. 
  

  

  