﻿Chemistry 
  and 
  Physics. 
  377 
  

  

  A 
  short 
  distance 
  in 
  front 
  of 
  the 
  magnet 
  a 
  wire 
  was 
  placed 
  at 
  

   right 
  angles 
  to 
  the 
  direction 
  of 
  the 
  rays, 
  and 
  in 
  the 
  plane 
  of 
  the 
  

   anti-cathode. 
  It 
  was 
  thus 
  at 
  an 
  angle 
  of 
  about 
  50° 
  to 
  the 
  mag- 
  

   netic 
  force 
  — 
  the 
  same 
  angle 
  as 
  that 
  between 
  the 
  axis 
  of 
  the 
  

   cathode 
  stream 
  and 
  the 
  anti-cathode. 
  This 
  wire 
  was 
  used 
  to 
  cast 
  

   a 
  shadow 
  on 
  a 
  photographic 
  plate 
  placed 
  at 
  a 
  distance 
  of 
  65 
  cm 
  on 
  

   the 
  other 
  side 
  of 
  the 
  magnet. 
  

  

  An 
  exposure 
  was 
  first 
  made 
  with 
  the 
  magnetic 
  force 
  in 
  one 
  

   direction. 
  The 
  exposure 
  was 
  then 
  stopped, 
  the 
  field 
  reversed, 
  

   and 
  another 
  exposure 
  given, 
  of 
  course 
  without 
  shifting 
  the 
  plate. 
  

   If 
  then 
  the 
  rays 
  had 
  been 
  appreciably 
  deflected, 
  the 
  photograph 
  

   should 
  have 
  shown 
  two 
  shadows, 
  either 
  overlapping, 
  or 
  altogether 
  

   separated. 
  

  

  The 
  rays 
  casting 
  the 
  shadow 
  were 
  those 
  emitted 
  at 
  a 
  grazing 
  

   angle 
  from 
  the 
  anti-cathode. 
  The 
  reason 
  for 
  using 
  these 
  very 
  

   oblique 
  rays 
  was 
  that 
  owing 
  to 
  the 
  foreshortening 
  of 
  the 
  anti- 
  

   cathode, 
  the 
  source 
  was 
  virtually 
  narrower 
  than 
  it 
  would 
  have 
  

   been, 
  had 
  rays 
  been 
  used 
  which 
  left 
  the 
  anti-cathode 
  at 
  a 
  greater 
  

   angle. 
  Thus 
  sharper 
  shadows 
  were 
  obtained, 
  and 
  a 
  smaller 
  mag- 
  

   netic 
  deflection 
  could 
  have 
  been 
  detected. 
  

  

  The 
  tube 
  was 
  arranged 
  with 
  its 
  cathode 
  stream 
  parallel 
  to 
  the 
  

   magnetic 
  field, 
  so 
  as 
  to 
  avoid 
  any 
  shifting 
  of 
  the 
  source 
  of 
  radia- 
  

   tion 
  when 
  the 
  magnet 
  was 
  reversed, 
  owing 
  to 
  an 
  eflect 
  of 
  the 
  

   magnet 
  on 
  the 
  original 
  cathode 
  beam. 
  Such 
  a 
  shifting 
  would 
  

   have 
  given 
  rise 
  to 
  a 
  spurious 
  effect. 
  The 
  only 
  objection 
  to 
  this 
  

   was 
  that 
  the 
  shadow-casting 
  wire 
  had 
  to 
  be 
  obliquely 
  placed 
  so 
  

   as 
  to 
  be 
  in 
  the 
  plane 
  of 
  the 
  anti-cathode. 
  Thus 
  some 
  sensitive- 
  

   ness 
  was 
  lost." 
  

  

  A 
  discussion 
  of 
  the 
  results 
  obtained 
  shows 
  that 
  a 
  field 
  of 
  a 
  

   strength 
  3270 
  C. 
  G. 
  S. 
  units 
  does 
  not 
  produce 
  a 
  curvature 
  of 
  

   radius 
  less 
  than 
  19,800 
  cm 
  , 
  hence 
  the 
  field 
  required 
  to 
  produce 
  a 
  

   curvature 
  of 
  l 
  cm 
  cannot 
  be 
  less 
  than 
  6*5 
  X 
  10 
  7 
  . 
  

  

  An 
  estimate 
  of 
  the 
  amount 
  of 
  magnetic 
  reflection 
  of 
  the 
  Bec- 
  

   querel 
  rays 
  was 
  also 
  made 
  ; 
  the 
  result 
  showed 
  a 
  radius 
  of 
  curva- 
  

   ture 
  of 
  3 
  cm 
  in 
  a 
  field 
  whose 
  strength 
  was 
  1680 
  C. 
  G. 
  S. 
  units. 
  

   Hence 
  the 
  field 
  required 
  to 
  produce 
  a 
  curvature 
  of 
  l 
  cm 
  is 
  about 
  

   5 
  X 
  10 
  3 
  . 
  Using 
  also 
  the 
  results 
  of 
  J. 
  J. 
  Thomson, 
  who 
  shows 
  that 
  

   a 
  beam 
  of 
  cathode 
  rays 
  was 
  bent 
  to 
  a 
  radius 
  of 
  curvature 
  of 
  9 
  cm 
  

   in 
  a 
  field 
  of 
  35 
  units, 
  it 
  is 
  calculated 
  that 
  a 
  field 
  of 
  315 
  would 
  

   have 
  been 
  required 
  to 
  bend 
  it 
  to 
  a 
  radius 
  of 
  l 
  cm 
  . 
  Hence 
  the 
  fol- 
  

   lowing 
  results 
  brought 
  together 
  for 
  comparison 
  : 
  

  

  " 
  The 
  field 
  which 
  would 
  be 
  required 
  to 
  produce 
  a 
  curvature 
  of 
  

   l 
  cm 
  radius 
  would 
  be 
  

  

  For 
  cathode 
  rays 
  3 
  X 
  10 
  a 
  

  

  " 
  Becquerel 
  rays 
  5X10 
  8 
  

  

  " 
  Rontgen 
  rays 
  not 
  less 
  than 
  ... 
  6X10 
  7 
  

  

  If 
  the 
  Rontgen 
  rays 
  are 
  magnetically 
  deflected 
  at 
  all, 
  it 
  is 
  by 
  

   an 
  amount 
  less 
  than 
  a 
  ten-thousandth 
  part 
  of 
  that 
  observed 
  in 
  the 
  

   case 
  of 
  the 
  Becquerel 
  rays. 
  

  

  Am. 
  Jour. 
  Scl— 
  Fourth 
  Series, 
  Vol. 
  IX, 
  No. 
  53.— 
  May, 
  1900. 
  

   26 
  

  

  