﻿824 
  

  

  Sir 
  J. 
  J. 
  Thomson 
  on 
  

  

  and 
  become 
  positively 
  charged 
  rays. 
  The 
  breaking 
  up 
  of 
  

   these 
  uncharged 
  rays 
  may 
  be 
  shown 
  and 
  the 
  rate 
  at 
  which 
  

   they 
  break 
  up 
  measured 
  by 
  the 
  following 
  method. 
  A 
  tube 
  

   (fig. 
  4) 
  in 
  which 
  the 
  distance 
  between 
  the 
  perforated 
  cathode 
  

  

  and 
  thewillemite 
  screen 
  was 
  considerably 
  greater 
  than 
  in 
  the 
  

   tube 
  fig. 
  1, 
  was 
  made, 
  and 
  two 
  electromagnets 
  arranged, 
  one 
  

   close 
  to 
  the 
  cathode, 
  and 
  the 
  other 
  much 
  nearer 
  the 
  screen. 
  

   The 
  magnets 
  were 
  arranged 
  so 
  that 
  the 
  magnetic 
  force 
  in 
  

   the 
  first 
  was 
  horizontal, 
  and 
  the 
  deflexion 
  of 
  the 
  spot 
  due 
  to 
  the 
  

   field 
  vertical, 
  while 
  in 
  the 
  second 
  magnet 
  the 
  magnetic 
  force 
  

   was 
  vertical 
  and 
  the 
  deflexion 
  horizontal. 
  The 
  deflexions 
  

   due 
  to 
  each 
  magnet 
  were 
  thus 
  separated 
  and 
  could 
  be 
  

   measured 
  independently. 
  

  

  The 
  effects 
  observed 
  when 
  the 
  magnets 
  were 
  applied 
  in 
  

   succession 
  and 
  then 
  simultaneously 
  are 
  interesting 
  ; 
  and 
  a 
  

   typical 
  case 
  is 
  represented 
  in 
  figs. 
  5 
  & 
  6. 
  Fig. 
  5 
  represents 
  

   the 
  appearance 
  of 
  the 
  screen 
  when 
  only 
  the 
  electromagnet 
  

   next 
  the 
  cathode 
  is 
  in 
  action 
  ; 
  fig. 
  6 
  the 
  appearance 
  when 
  

   both 
  magnets 
  are 
  on. 
  

  

  In 
  fig. 
  6 
  the 
  undeflected 
  spot 
  is 
  much 
  fainter 
  than 
  in 
  

   ^g. 
  5 
  ; 
  part 
  of 
  it 
  is 
  deflected 
  to 
  another 
  spot 
  a', 
  while 
  the 
  spot 
  b 
  

   is 
  deflected 
  to 
  h\ 
  V 
  is 
  vertically 
  under 
  a\ 
  so 
  that 
  the 
  deflexion 
  

   produced 
  by 
  the 
  second 
  electromagnet 
  on 
  the 
  rays 
  which 
  

   were 
  uncharged 
  when 
  they 
  went 
  through 
  the 
  first 
  electro- 
  

   magnet 
  is 
  the 
  same 
  as 
  that 
  produced 
  by 
  the 
  second 
  magnet 
  

   on 
  the 
  rays 
  which 
  were 
  charged 
  when 
  they 
  went 
  through 
  the 
  

   first 
  one. 
  It 
  is 
  evident 
  that 
  the 
  latter 
  have 
  for 
  the 
  most 
  part 
  

   kept 
  their 
  charge 
  from 
  the 
  cathode 
  right 
  through 
  the 
  second 
  

   magnet; 
  the 
  formation 
  of 
  the 
  spot 
  a! 
  shows 
  that 
  some 
  of 
  the 
  

   neutral 
  rays 
  have 
  in 
  their 
  journey 
  from 
  the 
  first 
  magnet 
  to 
  

   the 
  second 
  split 
  up 
  into 
  a 
  positive 
  and 
  negative 
  part 
  (the 
  

   negative 
  part 
  being 
  deflected 
  far 
  out 
  of 
  the 
  field 
  and 
  not 
  

  

  