﻿Field 
  upon 
  the 
  Electric 
  Discharge 
  through 
  Gases. 
  2G7 
  

  

  The 
  results 
  which 
  have 
  been 
  brought 
  out 
  in 
  this 
  paper 
  

   show 
  conclusively, 
  we 
  think, 
  that 
  the 
  function 
  of 
  the 
  mag- 
  

   netic 
  field 
  is 
  to 
  modify 
  the 
  discharge 
  rather 
  than 
  to 
  create 
  a 
  

   new 
  type 
  of 
  rays 
  such 
  as 
  has 
  been 
  proposed 
  by 
  Villard 
  and 
  

   Righi. 
  The 
  main 
  action 
  of 
  the 
  magnetic 
  field 
  is 
  to 
  reduce 
  

   greatly 
  the 
  potential 
  drop 
  at 
  the 
  cathode 
  and 
  to 
  force 
  charged 
  

   particles 
  in 
  the 
  tube 
  to 
  move 
  away 
  from 
  the 
  cathode 
  in 
  

   helical 
  paths. 
  Owing 
  to 
  their 
  greater 
  mobility 
  and 
  longer 
  

   free 
  path, 
  this 
  action 
  is 
  more 
  pronounced 
  on 
  electrons 
  than 
  

   on 
  positive 
  gaseous 
  ions. 
  

  

  For 
  convenience, 
  we 
  may 
  recapitulate 
  the 
  principal 
  results 
  

   which 
  support 
  this 
  view. 
  

  

  The 
  primary 
  effect 
  of 
  the 
  magnetic 
  field 
  is 
  to 
  produce 
  a 
  

   cone 
  of 
  bluish 
  rays 
  which 
  bends 
  toward 
  or 
  away 
  from 
  the 
  

   pole 
  of 
  an 
  auxiliary 
  magnet. 
  This 
  cone 
  is 
  a 
  stream 
  of 
  

   charged 
  particles 
  which 
  leaves 
  the 
  cathode 
  because 
  the 
  

   magnetic 
  field 
  lowers 
  the 
  potential 
  fall 
  at 
  the 
  cathode 
  and 
  

   exerts 
  a 
  mechanical 
  force 
  on 
  the 
  particles. 
  The 
  rays 
  have 
  

   been 
  found 
  to 
  be 
  negatively 
  charged 
  and 
  to 
  move 
  in 
  helical 
  

   ■paths. 
  A 
  similar 
  effect 
  is 
  obtained 
  when 
  a 
  Wehnelt 
  cathode 
  

   is 
  u-ed 
  without 
  a 
  magnetic 
  field, 
  except 
  that 
  the 
  path 
  is 
  not 
  

   helical 
  and 
  the 
  bundle 
  of 
  rays 
  is 
  cylindrical 
  and 
  not 
  conical, 
  

   both 
  of 
  which 
  differences 
  were 
  to 
  be 
  expected. 
  

  

  "When 
  we 
  consider 
  the 
  secondary 
  effects, 
  we 
  have 
  found 
  

   that 
  every 
  action 
  which 
  occurs 
  when 
  a 
  magnetic 
  field 
  acts 
  

   on 
  the 
  discharge 
  from 
  a 
  high 
  potential 
  cold 
  cathode 
  can 
  be 
  

   obtained 
  with 
  a 
  hot 
  W^ehnelt 
  cathode 
  when 
  there 
  is 
  no 
  

   magnetic 
  field. 
  These 
  actions 
  include 
  the 
  appearance 
  of 
  the 
  

   discharge, 
  the 
  periodicity, 
  the 
  induced 
  column 
  with 
  a 
  virtual 
  

   anode 
  and 
  reversed 
  bending. 
  In 
  addition, 
  we 
  found 
  a 
  true, 
  

   direct 
  but 
  fluctuating 
  current 
  between 
  the 
  interior 
  of 
  the 
  tube 
  

   and 
  an 
  earthed 
  screen 
  exterior 
  to 
  the 
  tube. 
  The 
  inference 
  is, 
  

   that 
  with 
  a 
  hot 
  Wehnelt 
  cathode 
  the 
  action 
  of 
  a 
  magnetic 
  

   field 
  is 
  not 
  to 
  change 
  the 
  nature 
  of 
  the 
  discharge, 
  but 
  to 
  

   d 
  is} 
  dace 
  it 
  from 
  the 
  cathode 
  and 
  to 
  magnify 
  it 
  so 
  that 
  the 
  

   various 
  parts 
  seem 
  to 
  be 
  changed. 
  

  

  It 
  give- 
  us 
  great 
  pleasure 
  to 
  express 
  our 
  thanks 
  to 
  Mr. 
  P. 
  

   B. 
  Evens, 
  whose 
  skill 
  in 
  devising 
  and 
  constructing 
  compli- 
  

   cated 
  apparatus 
  and 
  whose 
  patience 
  in 
  overcoming 
  difficulties 
  

   and 
  in 
  making 
  observations 
  have 
  done 
  much 
  to 
  make 
  our 
  

   work 
  successful. 
  

  

  University 
  <>i 
  Cincinnati, 
  

   broary, 
  1913. 
  

  

  T 
  2 
  

  

  