﻿Positive 
  Rays. 
  661 
  

  

  direction 
  to 
  the 
  Canals 
  trahlen, 
  that 
  a 
  considerable 
  number 
  

   of 
  them 
  are 
  negatively 
  charged 
  particles, 
  indeed 
  I 
  think 
  the 
  

   proportion 
  of 
  the 
  negative 
  to 
  the 
  positive 
  is 
  greater 
  in 
  this 
  

   case 
  than 
  in 
  that 
  of 
  the 
  Canalstrahlen. 
  I 
  have 
  observed 
  

   cases 
  in 
  which 
  the 
  phosphorescence 
  due 
  to 
  the 
  negatively 
  

   charged 
  particles 
  was 
  little, 
  if 
  at 
  all, 
  less 
  than 
  that 
  due 
  to 
  

   the 
  positively 
  charged 
  ones. 
  

  

  A 
  large 
  number 
  of 
  determinations 
  were 
  made, 
  by 
  the 
  

   method 
  described 
  in 
  my 
  first 
  paper 
  (Phil. 
  Mag. 
  xiii. 
  p. 
  561, 
  

   1907), 
  of 
  the 
  velocity 
  and 
  values 
  of 
  ejm 
  for 
  these 
  rays 
  ; 
  in 
  

   consequence 
  of 
  the 
  spot 
  of 
  phosphorescence 
  being 
  drawn 
  

   out 
  into 
  a 
  band, 
  the 
  values 
  of 
  ejm 
  ranged 
  continuously 
  from 
  

   to 
  a 
  maximum 
  value. 
  

  

  Two 
  tubes 
  were 
  used 
  for 
  this 
  purpose, 
  in 
  one 
  of 
  them 
  

   (fig. 
  1) 
  the 
  electrode 
  Bwas 
  connected 
  with 
  a 
  stopper 
  ground 
  

   into 
  the 
  tube, 
  one 
  side 
  of 
  the 
  electrode 
  was 
  aluminium, 
  the 
  

   other 
  calcium 
  : 
  by 
  turning 
  the 
  stopper 
  either 
  side 
  could 
  be 
  

   made 
  to 
  face 
  the 
  tube 
  A, 
  down 
  which 
  the 
  rays 
  passed. 
  L 
  M 
  

   are 
  parallel 
  plates, 
  which 
  can 
  be 
  connected 
  with 
  a 
  battery 
  of 
  

   storage-_cells 
  ; 
  when 
  this 
  is 
  done 
  rays 
  passing 
  between 
  the 
  

   plates 
  are 
  acted 
  on 
  by 
  a 
  strong 
  electric 
  field. 
  S 
  is 
  the 
  screen 
  

   at 
  the 
  end 
  of 
  the 
  tube. 
  H, 
  K 
  the 
  pole-pieces 
  of 
  the 
  electro- 
  

   magnets. 
  C 
  is 
  a 
  wire 
  fused 
  into 
  the 
  tube, 
  to 
  serve 
  as 
  an 
  

   electrode, 
  thns 
  allowing 
  A 
  to 
  be 
  insulated 
  or 
  connected 
  with 
  

   one 
  or 
  other 
  of 
  the 
  electrodes 
  at 
  will. 
  The 
  dimensions 
  of 
  

   the 
  parts 
  of 
  the 
  tube 
  which 
  affect 
  the 
  deflexions 
  of 
  the 
  

   phosphorescence 
  are 
  as 
  follows 
  : 
  — 
  

  

  Distance 
  between 
  the 
  plates 
  L 
  and 
  M 
  = 
  '45 
  cm. 
  

   Length 
  of 
  these 
  plates 
  .... 
  =3'8 
  cm. 
  

   Distance 
  between 
  the 
  screen 
  and 
  the 
  

  

  end 
  of 
  the 
  plates 
  =4*0 
  cm. 
  

  

  If 
  V 
  is 
  the 
  potential 
  in 
  volts 
  between 
  the 
  plates, 
  e 
  the 
  

   charge, 
  m 
  the 
  mass, 
  and 
  v 
  the 
  velocity 
  of 
  the 
  rays, 
  D 
  the 
  

   deflexion 
  due 
  to 
  the 
  electrostatic 
  field, 
  we 
  can 
  easily 
  prove 
  

   that 
  

  

  e 
  D 
  

  

  mv 
  

  

  ? 
  ox 
  10 
  (J 
  V 
  

  

  "While 
  if 
  d 
  is 
  the 
  deflexion 
  due 
  to 
  the 
  magnetic 
  field 
  when 
  a 
  

   current 
  of 
  1 
  ampere 
  is 
  passing 
  through 
  the 
  coils, 
  it 
  was 
  found 
  

   by 
  the 
  method 
  described 
  in 
  Phil. 
  Mag. 
  xiii. 
  p. 
  561, 
  that 
  

  

  mv 
  2'$ 
  X 
  10 
  4 
  

  

  