﻿100 
  H. 
  A. 
  Bumstead 
  — 
  Velocities 
  of 
  Delta 
  Bays. 
  

  

  three 
  sides 
  of 
  a 
  rectangle. 
  One 
  side 
  of 
  this 
  rectangle, 
  21 
  cm 
  

   long, 
  was 
  surrounded 
  by 
  the 
  magnetizing 
  coil 
  ; 
  the 
  other 
  two 
  

   sides, 
  18 
  cm 
  long, 
  embraced 
  the 
  case, 
  as 
  shown 
  in 
  fig. 
  2, 
  and 
  

   formed 
  long, 
  narrow 
  pole 
  pieces. 
  Along 
  these 
  pole 
  pieces, 
  

   from 
  their 
  ends 
  nearly 
  to 
  the 
  magnetizing 
  coil, 
  the 
  field 
  was 
  

   fairly 
  uniform, 
  not 
  varying 
  more 
  than 
  10 
  per 
  cent, 
  when 
  

   measured 
  by 
  a 
  fluxmeter. 
  In 
  the 
  other 
  two 
  directions 
  at 
  right 
  

   angles 
  to 
  this, 
  the 
  variation 
  of 
  the 
  field 
  was 
  rapid 
  on 
  account 
  

   of 
  the 
  spreading 
  out 
  of 
  the 
  lines 
  of 
  force 
  in 
  the 
  large 
  air-gap. 
  

   With 
  a 
  current 
  of 
  5 
  amperes, 
  for 
  example, 
  the 
  field 
  near 
  either 
  

   pole-piece 
  was 
  530 
  gausses, 
  while 
  half-way 
  between 
  them, 
  and 
  

   in 
  their 
  plane, 
  it 
  was 
  250. 
  The 
  field 
  at 
  any 
  one 
  point 
  was 
  

   nearly 
  proportional 
  to 
  the 
  current 
  in 
  the 
  coil 
  from 
  1 
  to 
  8 
  

   amperes. 
  Before 
  using 
  the 
  magnetic 
  field, 
  the 
  ■ 
  brass 
  box 
  

   which 
  served 
  as 
  the 
  electrode 
  and 
  the 
  source 
  of 
  S-rays 
  was 
  

   provided 
  with 
  the 
  brass 
  ring 
  shown 
  in 
  fig. 
  2 
  (forming 
  the 
  brim 
  

   of 
  the 
  " 
  hat 
  "), 
  which 
  had 
  not 
  been 
  present 
  in 
  the 
  preceding 
  

   experiments. 
  Its 
  purpose 
  was 
  to 
  catch 
  the 
  S-electrons, 
  

   originating 
  near 
  one 
  side 
  of 
  the 
  box 
  when 
  they 
  were 
  bent 
  by 
  

   the 
  magnetic 
  field 
  toward 
  that 
  side. 
  The 
  addition 
  of 
  this 
  ring, 
  

   by 
  increasing 
  the 
  capacity 
  of 
  the 
  electrode, 
  decreased 
  some- 
  

   what 
  the 
  readings 
  of 
  the 
  electroscope. 
  

  

  With 
  the 
  magnetic 
  field, 
  the 
  electrode 
  charged 
  up 
  negatively, 
  

   the 
  rate 
  reaching 
  a 
  maximum 
  value 
  with 
  a 
  current 
  of 
  3 
  

   amperes 
  on 
  the 
  magnet 
  and 
  not 
  changing 
  when 
  the 
  current 
  

   was 
  increased 
  to 
  9 
  amperes. 
  It 
  was 
  independent 
  of 
  the 
  potential 
  

   applied 
  to 
  the 
  gauze 
  from 
  —40 
  volts 
  to 
  —1200, 
  but 
  it 
  did 
  vary 
  

   with 
  the 
  time 
  after 
  the 
  vacuum 
  was 
  made 
  in 
  the 
  same 
  manner 
  

   as 
  the 
  results 
  obtained 
  previously. 
  For 
  example, 
  with 
  —40 
  

   volts 
  on 
  the 
  gauze, 
  and 
  a 
  magnetic 
  field 
  of 
  250 
  units, 
  the 
  fol- 
  

   lowing 
  values 
  of 
  the 
  current 
  were 
  obtained 
  at 
  different 
  times 
  

   after 
  the 
  application 
  of 
  the 
  liquid 
  air 
  to 
  the 
  charcoal 
  : 
  

  

  1 
  hour 
  ._ 
  126 
  divisions 
  per 
  minute. 
  

  

  3 
  hours. 
  _. 
  72 
  " 
  " 
  " 
  

  

  24 
  " 
  25 
  " 
  " 
  " 
  

  

  48 
  " 
  _.. 
  12 
  " 
  " 
  " 
  

  

  72 
  " 
  9 
  " 
  " 
  -" 
  

  

  We 
  are, 
  I 
  think, 
  justified 
  in 
  concluding 
  that 
  the 
  carriers 
  of 
  

   this 
  current 
  are 
  not 
  electrons, 
  but 
  ions 
  of 
  atomic 
  mass. 
  Thus, 
  

   in 
  a 
  magnetic 
  field 
  of 
  250 
  gausses, 
  an 
  electron 
  whose 
  velocity 
  

   was 
  as 
  great 
  as 
  that 
  corresponding 
  to 
  1600 
  volts 
  would 
  be 
  

   curled 
  into 
  a 
  circle 
  of 
  only 
  half 
  a 
  centimeter 
  radius, 
  and 
  could 
  

   scarcely 
  reach 
  the 
  electrode 
  even 
  if 
  it 
  started 
  from 
  the 
  case 
  

   with 
  that 
  velocity 
  ; 
  and 
  there 
  is 
  no 
  evidence 
  that 
  any 
  swift 
  

   electrons 
  start 
  from 
  the 
  case 
  at 
  all. 
  On 
  the 
  other 
  hand, 
  a 
  

  

  