﻿Si2 
  Sir 
  J. 
  J. 
  Thomson 
  on 
  

  

  symmetrical 
  on 
  the 
  two 
  sides 
  of 
  the 
  hole. 
  I£ 
  a 
  strong 
  

   magnetic 
  field 
  is 
  applied 
  to 
  the 
  neighbourhood 
  o£ 
  the 
  hole,, 
  

   the 
  lines 
  of 
  force 
  being 
  parallel 
  to 
  the 
  surface 
  of 
  the 
  cathode,, 
  

   some 
  very 
  interesting 
  effects 
  are 
  observed. 
  Those 
  in 
  the 
  

  

  Fiff. 
  9. 
  

  

  most 
  deveoped 
  form 
  are 
  represented 
  in 
  fig. 
  10; 
  unless 
  the 
  

   pressure 
  is 
  within 
  certain 
  limits 
  one 
  or 
  other 
  of 
  these 
  parts 
  

   may 
  be 
  absent, 
  a 
  and 
  a' 
  are 
  two 
  streamers 
  coming 
  from 
  

   the 
  hole 
  and 
  following 
  the 
  directions 
  of 
  the 
  lines 
  of 
  magnetic 
  

   force. 
  In 
  this 
  respect 
  they 
  resemble 
  the 
  magneto-cathodic 
  

   rays 
  of 
  Yillard 
  and 
  Righi, 
  but 
  whatever 
  may 
  be 
  the 
  nature 
  

   of 
  the 
  magneto-cathodic 
  rays 
  in 
  front 
  of 
  the 
  cathode, 
  there 
  

   can 
  be 
  no 
  doubt, 
  I 
  think, 
  that 
  the 
  rays 
  we 
  are 
  describing 
  

   consist 
  of 
  slowly 
  moving 
  corpuscles 
  describing 
  spirals 
  of 
  very 
  

   small 
  radius 
  around 
  the 
  lines 
  of 
  force 
  : 
  for, 
  as 
  the 
  magnetic 
  

   force 
  is 
  very 
  gradually 
  reduced, 
  we 
  reach 
  the 
  stage 
  when 
  the 
  

   widening 
  of 
  the 
  radii 
  of 
  these 
  spirals 
  becomes 
  so 
  large 
  that 
  

   the 
  spiral 
  nature 
  of 
  their 
  path 
  becomes 
  quite 
  obvious. 
  That 
  

   they 
  are 
  carriers 
  of 
  negative 
  electricity 
  can 
  easily 
  be 
  shown 
  

   by 
  sending 
  them 
  into 
  a 
  carefully 
  insulated 
  Faraday 
  cylinder 
  

   surrounded 
  by 
  another 
  cylinder 
  with 
  a 
  hole 
  in 
  it. 
  

  

  The 
  outer 
  cylinder 
  was 
  put 
  to 
  earth, 
  the 
  inner 
  one 
  was 
  

   connected 
  with 
  a 
  sensitive 
  galvanometer 
  (the 
  one 
  I 
  used 
  gave 
  

   a 
  deflexion 
  of 
  1 
  mm. 
  at 
  one 
  metre 
  for 
  3 
  x 
  10~^^ 
  ampere). 
  

   When 
  one 
  of 
  the 
  streams 
  passed 
  through 
  the 
  hole 
  in 
  the 
  

   outer 
  cylinder 
  there 
  was 
  a 
  deflexion 
  of 
  70 
  or 
  80 
  scale- 
  

   divisions 
  in 
  the 
  direction 
  corresponding 
  to 
  a 
  flow 
  of 
  negative 
  

   electricity 
  into 
  the 
  Faraday 
  cylinder. 
  

  

  The 
  other 
  two 
  luminous 
  portions 
  c 
  and 
  d 
  are 
  bent 
  at 
  

   right 
  angles 
  to 
  the 
  direction 
  of 
  the 
  magnetic 
  forces, 
  just 
  

  

  