﻿900 
  Doppler 
  Effect 
  in 
  Positive 
  Rays 
  in 
  Hydrogen. 
  

  

  In 
  the 
  following 
  table 
  are 
  given 
  the 
  ratios 
  between 
  the 
  

  

  observed 
  and 
  calculated 
  velocities 
  assuming 
  — 
  =9654. 
  In 
  

  

  column 
  1 
  the 
  minimum 
  velocity 
  in 
  front 
  of 
  the 
  cathode 
  is 
  

   compared 
  with 
  the 
  potential 
  fall 
  from 
  the 
  negative 
  glow 
  to 
  

   the 
  commencement 
  of 
  the 
  cathode 
  glow 
  (400 
  volts 
  for 
  cathode 
  

   fall 
  of 
  2650 
  volts). 
  Columns 
  2 
  and 
  3 
  refer 
  to 
  the 
  canal 
  rays 
  

   behind 
  the 
  cathode 
  with 
  the 
  same 
  cathode 
  fall 
  of 
  potential, 
  

   these 
  being 
  less 
  complicated 
  than 
  in 
  front 
  of 
  the 
  cathode 
  

   since 
  all 
  rays 
  have 
  passed 
  through 
  the 
  cathode 
  fall. 
  

  

  Table 
  III. 
  

   -p 
  . 
  observed 
  velocity 
  

   calculated 
  velocity. 
  

  

  

  Minimum 
  in 
  

   front 
  of 
  cathode. 
  

  

  Densest 
  portion 
  behind 
  

   the 
  cathode. 
  

  

  Maximum 
  behind 
  

   the 
  cathode. 
  

  

  Ha... 
  

  

  •43 
  

   •52 
  

   •54 
  

  

  I 
  -36 
  

  

  I 
  ^56 
  

  

  It 
  is 
  seen 
  that 
  the 
  ratio 
  for 
  the 
  minimum 
  in 
  front 
  of 
  the 
  

   vcathode 
  is 
  about 
  the 
  same 
  as 
  for 
  the 
  maximum 
  behind 
  the 
  

   cathode. 
  

  

  Since 
  the 
  minimum 
  velocity 
  in 
  front 
  of 
  the 
  cathode 
  was 
  

   found 
  to 
  be 
  not 
  constant 
  for 
  different 
  wavelengths, 
  measure- 
  

   ments 
  were 
  also 
  made 
  for 
  the 
  canal 
  rays 
  behind 
  the 
  cathode. 
  

   It 
  was 
  observed 
  in 
  agreement 
  with 
  Stark 
  and 
  Steubing 
  that 
  

   the 
  minimum 
  velocity 
  was 
  smaller 
  for 
  greater 
  wavelengths. 
  

   For 
  the 
  point 
  of 
  maximum 
  density, 
  however, 
  the 
  variations 
  

   were 
  within 
  the 
  limits 
  of 
  error, 
  even 
  for 
  the 
  outer 
  strip 
  

   observed 
  with 
  a 
  cathode 
  fall 
  of 
  550 
  volts. 
  

  

  I 
  wish 
  to 
  express 
  my 
  thanks 
  to 
  Prof. 
  Dr. 
  Faschen 
  for 
  his 
  

   interest 
  in 
  these 
  experiments 
  and 
  the 
  numerous 
  suggestions 
  

   he 
  has 
  made* 
  

  

  Physikalisches 
  Institut, 
  Tiibingen, 
  

   Aug. 
  4th, 
  1909. 
  

  

  