﻿Canal 
  Rays 
  from 
  Hollow 
  Cathodes. 
  

  

  175 
  

  

  that 
  the 
  rays 
  travelling 
  from 
  the 
  cathode 
  towards 
  the 
  

   anode 
  appear 
  to 
  have 
  the 
  same 
  properties 
  as 
  those 
  going 
  in 
  

  

  Fiff. 
  15. 
  

  

  the 
  opposite 
  direction, 
  whereas 
  in 
  the 
  ordinary 
  tube 
  used 
  for 
  

   canal-rays 
  we 
  find 
  these 
  positive 
  rays 
  starting 
  from 
  the 
  

   cathode 
  in 
  a 
  direction 
  opposite 
  to 
  the 
  cathode 
  rays. 
  In 
  the 
  

   present 
  arrangement, 
  however, 
  no 
  canal-rays 
  were 
  found 
  at 
  

   the 
  surface 
  of 
  the 
  glass 
  wall 
  ; 
  but 
  a 
  red 
  light 
  was 
  observed 
  

   not 
  unlike 
  the 
  velvet 
  glow 
  along 
  the 
  surface 
  of 
  the 
  holes. 
  

   Nevertheless 
  it 
  is 
  possible 
  that 
  some 
  canal-rays 
  escape 
  from 
  

   the 
  openings 
  without 
  being 
  capable 
  of 
  observation 
  under 
  the 
  

   given 
  circumstances. 
  

  

  In 
  the 
  following 
  experiment 
  the 
  metal 
  sphere 
  was 
  sur- 
  

   rounded 
  by 
  a 
  sheet 
  of 
  sulphur 
  2 
  mm. 
  thick, 
  so 
  that 
  only 
  the 
  

   walls 
  of 
  the 
  five 
  holes 
  and 
  a 
  part 
  of 
  the 
  surface 
  in 
  front 
  of 
  

   the 
  anode 
  were 
  free 
  from 
  insulation 
  ; 
  so 
  we 
  might 
  expect 
  

   to 
  get 
  canal-rays 
  in 
  the 
  opposite 
  direction. 
  Very 
  bright 
  

   blue 
  beams 
  start, 
  however, 
  from 
  all 
  the 
  five 
  holes 
  having 
  the 
  

   same 
  qualities 
  in 
  each 
  direction 
  ; 
  a 
  red 
  glow 
  in 
  the 
  middle 
  of 
  

   the 
  cathode 
  may 
  easily 
  be 
  observed, 
  recalling 
  the 
  colour 
  of 
  

  

  