﻿Wellisch 
  and 
  Woodroiv 
  — 
  Columnar 
  Ionization. 
  221 
  

  

  The 
  narrow 
  brass 
  pieces 
  were 
  now 
  removed 
  from 
  the 
  ends 
  

   of 
  the 
  slit 
  and 
  a 
  brass 
  plate 
  2 
  mm 
  in 
  width 
  was 
  placed 
  over 
  the 
  

   central 
  portion 
  of 
  the 
  slit 
  so 
  that 
  now 
  the 
  ionization 
  was 
  mostly 
  

   due 
  to 
  the 
  oblique 
  rays. 
  The 
  values 
  of 
  r 
  l 
  and 
  r 
  t 
  are 
  tabulated 
  

   in 
  Table 
  V. 
  The 
  fact 
  that 
  r 
  t 
  is 
  much 
  greater 
  than 
  r 
  t 
  for 
  high 
  

   values 
  of 
  the 
  electric 
  field 
  shows 
  that 
  the 
  oblique 
  rays 
  were 
  

   responsible 
  for 
  the 
  small 
  values 
  of 
  r 
  t 
  relatively 
  to 
  those 
  of 
  

   r, 
  when 
  the 
  whole 
  slit 
  was 
  employed 
  as 
  described 
  above. 
  

  

  Table 
  V. 
  

   Oblique 
  rays. 
  d=2 
  - 
  68cin.; 
  r=i 
  760 
  /ia84. 
  

  

  Longitudinal 
  Field. 
  

  

  Transverse 
  Field. 
  

  

  P- 
  

  

  X. 
  

  

  iu 
  

  

  n_. 
  

  

  X. 
  

  

  it. 
  r 
  t 
  . 
  

  

  284 
  

   760 
  

   760 
  

  

  1580 
  

  

  420 
  

  

  1580 
  

  

  0-917 
  

  

  3-04 
  

  

  3-15 
  

  

  3-31 
  

   3-45 
  

  

  630 
  

   630 
  

  

  0-808 
  

   2-55 
  

  

  3-16 
  

  

  In 
  order 
  to 
  examine 
  more 
  closely 
  the 
  effect 
  when 
  the 
  oblique 
  

   rays 
  alone 
  were 
  made 
  effective 
  by 
  eliminating 
  those 
  from 
  the 
  

   central 
  portion 
  of 
  the 
  slit, 
  readings 
  were 
  taken 
  of 
  the 
  ioniza- 
  

   tion 
  current 
  for 
  different 
  gas 
  pressures 
  in 
  both 
  the 
  longitudinal 
  

   and 
  transverse 
  fields. 
  From 
  the 
  figures 
  given 
  in 
  Table 
  YI, 
  

   one 
  sees 
  that 
  the 
  increase 
  of 
  the 
  current 
  with 
  the 
  pressure 
  is 
  

   quite 
  normal 
  in 
  the 
  case 
  of 
  the 
  longitudinal 
  field, 
  but 
  that 
  the 
  

   current 
  at 
  a 
  pressure 
  of 
  760 
  mm 
  of 
  mercury 
  in 
  the 
  transverse 
  

   field 
  shows 
  a 
  distinct 
  falling 
  off 
  from 
  the 
  normal 
  law. 
  This 
  

   result 
  was 
  surprising 
  in 
  view 
  of 
  the 
  calculations 
  for 
  the 
  posi- 
  

   tion 
  of 
  the 
  cone 
  of 
  rays 
  emerging 
  from 
  the 
  slit. 
  It 
  indicates 
  

   probably 
  that 
  an 
  appreciable 
  fraction 
  of 
  the 
  alpha 
  particles 
  are 
  

   scattered 
  into 
  the 
  electrodes 
  of 
  the 
  transverse 
  field, 
  thus 
  

   diminishing 
  the 
  ionization 
  current. 
  In 
  the 
  longitudinal 
  field 
  

   there 
  would 
  not 
  be 
  a 
  diminution 
  of 
  the 
  current, 
  as 
  the 
  particles 
  

   would 
  be 
  merely 
  scattered 
  in 
  the 
  gas. 
  

  

  The 
  experimental 
  results 
  obtained 
  when 
  the 
  rays 
  were 
  

   canalized 
  are 
  thus 
  the 
  only 
  results 
  which 
  admit 
  of 
  strict 
  inter- 
  

   pretation 
  ; 
  and 
  they 
  show 
  that 
  r 
  t 
  and 
  r 
  t 
  both 
  tend 
  to 
  the 
  same 
  

   maximum 
  value. 
  In 
  other 
  words, 
  in 
  accordance 
  with 
  the 
  view 
  

   generally 
  accepted, 
  the 
  current 
  resulting 
  from 
  alpha-ray 
  ioniza- 
  

   tion 
  has 
  the 
  same 
  saturation 
  value 
  whether 
  the 
  electric 
  field 
  is 
  

   longitudinal 
  or 
  transverse, 
  the 
  continued 
  slope 
  of 
  the 
  ionization 
  

   curve 
  for 
  the 
  longitudinal 
  field 
  being 
  due 
  entirely 
  to 
  'lack 
  of 
  

   saturation 
  ' 
  occasioned 
  by 
  the 
  recombination 
  of 
  ions. 
  

  

  