﻿Action 
  of 
  Magnetic- 
  Field 
  upon 
  Electric 
  Discharge. 
  253 
  

  

  polaritv. 
  "Wo 
  may 
  cull 
  these 
  magnetic 
  rays 
  the 
  primary 
  

   effect 
  of 
  the 
  magnetic 
  field. 
  

  

  Professor 
  Righi 
  tried 
  many 
  different 
  forms 
  of 
  tubes, 
  and 
  

   finally 
  adopted 
  one 
  in 
  which 
  the 
  anode 
  was 
  placed 
  in 
  a 
  side 
  

   branch, 
  and 
  the 
  part 
  into 
  which 
  the 
  magnetic 
  rays 
  extended 
  

   was 
  enlarged 
  into 
  a 
  cylinder 
  about 
  a 
  metre 
  long 
  and 
  seven 
  or 
  

   eight 
  centimetres 
  in 
  diameter. 
  He 
  then 
  found 
  when 
  the 
  

   held 
  was 
  excited, 
  that 
  this 
  large 
  tube 
  became 
  filled 
  with 
  an 
  

   electric 
  glow 
  discharge, 
  to 
  which 
  we 
  have 
  given 
  the 
  name 
  of 
  

   " 
  the 
  induced 
  column,'' 
  for 
  it 
  evidently 
  is 
  dependent 
  on 
  the 
  

   primary 
  magnetic 
  rays 
  and 
  is 
  thus 
  secondary 
  in 
  nature. 
  

  

  Professor 
  Rio-hi 
  describes 
  this 
  induced 
  column 
  as 
  a 
  column 
  

   of 
  light 
  beginning 
  near 
  the 
  base 
  of 
  the 
  conical 
  magnetic 
  rays 
  

   and 
  tilling 
  practically 
  the 
  whole 
  tube. 
  Somewhere 
  near 
  the 
  

   middle 
  of 
  the 
  column 
  is 
  a 
  region 
  of 
  comparative 
  darkness 
  

   which 
  contains 
  an 
  excess 
  o£ 
  positive 
  ions 
  ; 
  and 
  at 
  the 
  far 
  

   end 
  of 
  the 
  tube 
  there 
  is 
  a 
  similar 
  place 
  showing 
  an 
  excess 
  of 
  

   negative 
  electricity. 
  This 
  virtual 
  anode 
  causes 
  a 
  current 
  of 
  

   positive 
  electricity 
  to 
  flow 
  from 
  the 
  middle 
  of 
  the 
  column 
  to 
  

   the 
  two 
  ends 
  of 
  the 
  tube. 
  This 
  is 
  shown 
  by 
  the 
  fact 
  that 
  if 
  

   the 
  pole 
  of 
  a 
  test-magnet 
  is 
  moved 
  along 
  the 
  column, 
  the 
  

   light 
  is 
  deflected 
  in 
  a 
  circular 
  arc 
  about 
  the 
  pole 
  and 
  the 
  

   convexities 
  of 
  the 
  curves 
  of 
  the 
  two 
  portions 
  of 
  the 
  column 
  

   are 
  in 
  opposite 
  directions, 
  indicating 
  currents 
  flowing 
  in 
  

   contrary 
  directions. 
  The 
  colour 
  of 
  the 
  light 
  in 
  the 
  two 
  

   portions 
  of 
  the 
  column 
  is 
  different 
  ; 
  it 
  is 
  blue 
  in 
  the 
  half 
  

   nearer 
  the 
  cathode 
  and 
  pinkish 
  in 
  the 
  farther 
  half. 
  

  

  The 
  induced 
  column 
  is 
  sometimes 
  striated 
  and 
  it 
  is 
  always 
  

   periodic. 
  This 
  periodicity 
  is 
  shown 
  in 
  several 
  ways. 
  A 
  clear 
  

   musical 
  note 
  of 
  high 
  pitch 
  is 
  emitted 
  ; 
  the 
  lijjht 
  viewed 
  in 
  a 
  

   rotating 
  mirror 
  is 
  banded 
  ; 
  and 
  a 
  telephone 
  introduced 
  in 
  the 
  

   circuit 
  buzzes. 
  

  

  The 
  virtual 
  anode, 
  Professor 
  Righi 
  assumes 
  to 
  be 
  the 
  

   location 
  of 
  the 
  limit 
  of 
  the 
  paths 
  of 
  the 
  positive 
  ions 
  set 
  free 
  

   by 
  the 
  dissociation 
  of 
  the 
  ion-electron 
  doublets, 
  and 
  the 
  

   virtual 
  cathode 
  at 
  the 
  far 
  end 
  of 
  the 
  tube 
  is 
  the 
  similar 
  limit 
  

   of 
  the 
  paths 
  of 
  the 
  freed 
  electrons. 
  

  

  Work 
  was 
  begun 
  in 
  this 
  laboratory 
  somewhat 
  over 
  two 
  

   years 
  ago 
  with 
  the 
  intention 
  of 
  confirming 
  and 
  extending 
  

   these 
  discoveries 
  and 
  the 
  theory 
  of 
  Professor 
  Righi. 
  In 
  an 
  

   article 
  * 
  published 
  in 
  this 
  magazine, 
  his 
  results 
  were 
  con- 
  

   firmed, 
  but 
  characteristic 
  variations 
  were 
  found 
  when 
  the 
  

   tube 
  was 
  filled 
  with 
  gases 
  other 
  than 
  air, 
  which 
  had 
  been 
  the 
  

   only 
  one 
  hitherto 
  used. 
  

  

  The 
  authors 
  found 
  that 
  the 
  magnetic 
  rays 
  themselves 
  were 
  

   • 
  More 
  & 
  Rieman, 
  Phil. 
  Mag. 
  vol. 
  xxiv. 
  p. 
  307 
  (1912). 
  

  

  