﻿Canal' 
  Rays 
  from 
  Hollow 
  Cathodes. 
  177 
  

  

  helium. 
  As 
  we 
  go 
  on 
  lowering 
  the 
  pressure 
  the 
  cathode 
  rays 
  A 
  

   cease 
  to 
  be 
  visible 
  in 
  the 
  gas, 
  while 
  now 
  the 
  red 
  rays 
  B, 
  of 
  

  

  Figr. 
  1' 
  

  

  fio-s. 
  18 
  and 
  19 
  (p. 
  178), 
  pass 
  through 
  a 
  maximum 
  of 
  brightness. 
  

   The 
  phosphorescence 
  on 
  the 
  glass 
  wall 
  due 
  to 
  these 
  rays 
  is 
  very 
  

   faint. 
  In 
  one 
  case 
  only 
  I 
  was 
  able 
  to 
  detect 
  the 
  sodium 
  line 
  in 
  

   the 
  spectrum 
  of 
  the 
  same. 
  The 
  red 
  rays 
  travelling 
  from 
  the 
  

   corners 
  of 
  the 
  triangle 
  seem 
  not 
  to 
  be 
  deflected 
  by 
  a 
  magnetic 
  

   field 
  of 
  moderate 
  strength. 
  Professor 
  J. 
  J. 
  Thomson, 
  who 
  

   applied 
  a 
  very 
  strong 
  field 
  to 
  these 
  rays, 
  could 
  find 
  so 
  far 
  no 
  

   deflexion 
  at 
  all. 
  He 
  found, 
  moreover, 
  that 
  rays 
  of 
  this 
  kind 
  

   not 
  only 
  leave 
  the 
  triangle 
  from 
  the 
  corners 
  but 
  also 
  from 
  

   the 
  sides 
  without 
  being 
  susceptible 
  of 
  magnetic 
  deflexion. 
  

   At 
  a 
  very 
  low 
  pressure 
  the 
  cathode 
  rays 
  also, 
  though 
  invisible 
  

   in 
  the 
  gas, 
  start 
  nearly 
  round 
  about 
  the 
  triangle 
  and 
  produce 
  

   alono* 
  the 
  meridian 
  of 
  the 
  glass 
  bulb 
  a 
  band 
  of 
  phosphorescence. 
  

   This 
  phosphorescence 
  presents 
  a 
  maximum 
  of 
  luminosity 
  at 
  

   reo-ions 
  in 
  front 
  of 
  the 
  sides 
  of 
  the 
  cathode. 
  It 
  is 
  scarcely 
  

   interrupted 
  opposite 
  the 
  corners 
  and 
  is 
  accompanied 
  on 
  either 
  

   Phil. 
  Mag. 
  S. 
  6. 
  Vol. 
  16. 
  No. 
  91. 
  July 
  1908. 
  N 
  

  

  