﻿518 
  Prof. 
  Wellisch 
  and 
  Dr. 
  Woodrow 
  : 
  Experiments 
  

  

  In 
  order 
  to 
  ascertain 
  the 
  reason 
  for 
  the 
  discrepancy 
  

   between 
  the 
  results 
  obtained 
  when 
  the 
  slit 
  and 
  the 
  canals 
  

   were 
  employed, 
  experiments 
  were 
  performed 
  in 
  which 
  only 
  

   small 
  portions 
  o£ 
  the 
  slit 
  previously 
  employed 
  were 
  effective. 
  

   The 
  oblique 
  rays 
  were 
  eliminated 
  by 
  placing 
  narrow 
  pieces 
  

   of 
  brass 
  over 
  the 
  ends 
  of 
  the 
  slit 
  so 
  as 
  to 
  leave 
  an 
  opening 
  in 
  

   the 
  centre 
  1*7 
  mm. 
  in 
  length 
  and 
  0*5 
  mm. 
  in 
  width. 
  The 
  

   corresponding 
  values 
  of 
  ri 
  and 
  r 
  t 
  are 
  given 
  in 
  Table 
  IV. 
  : 
  it 
  

   will 
  be 
  seen 
  that 
  the 
  ratios 
  for 
  the 
  longitudinal 
  and 
  trans- 
  

   verse 
  fields 
  have 
  approximately 
  the 
  same 
  maximum 
  values. 
  

   The 
  results 
  thus 
  serve 
  to 
  confirm 
  those 
  obtained 
  when 
  the 
  

   canals 
  were 
  employed. 
  

  

  Table 
  IV. 
  

  

  d=2'6S 
  cm. 
  ; 
  r 
  = 
  i 
  76o 
  /ip. 
  

  

  

  Longitudinal 
  Field. 
  

  

  Transverse 
  Field. 
  

  

  p. 
  

  

  X. 
  

  

  H- 
  

  

  n- 
  

  

  X. 
  

  

  H- 
  

  

  n- 
  

  

  284 
  mm. 
  

   400 
  

   596 
  

   760 
  

  

  1580 
  

   1580 
  

   1580 
  

   1580 
  

  

  0-560 
  

   0-828 
  

   1-370 
  

   1-914 
  

  

  3-42 
  

   2-24 
  

   1-40 
  

   TOO 
  

  

  630 
  

   630 
  

   630 
  

   630 
  

  

  0-391 
  

   0-588 
  

   0962 
  

   1-330 
  

  

  340 
  

  

  2-27 
  

   1-38 
  

   1-00 
  

  

  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 
  n 
  and 
  r 
  t 
  are 
  

   tabulated 
  in 
  Table 
  V. 
  The 
  fact 
  that 
  n 
  is 
  much 
  greater 
  than 
  

  

  Table 
  V. 
  

  

  Oblique 
  rays. 
  d 
  = 
  2'68 
  cm. 
  ; 
  r 
  = 
  i 
  760 
  /i 
  284 
  . 
  

  

  

  Longitudinal 
  Field. 
  

  

  Transverse 
  Field. 
  

  

  p. 
  

  

  X. 
  

  

  H> 
  

  

  n> 
  

  

  X. 
  

  

  if 
  

  

  r 
  f 
  

  

  284 
  

   760 
  

   760 
  

  

  1580 
  

  

  420 
  

  

  1580 
  

  

  0-917 
  

  

  3-04 
  

  

  3-15 
  

  

  331 
  

   3-45 
  

  

  630 
  

   630 
  

  

  0-808 
  

   2-55 
  

  

  3-16 
  

  

  