﻿896 
  

  

  Mr. 
  T. 
  Royds 
  on 
  the 
  Doppler 
  Effect 
  

  

  length 
  of 
  the 
  dark 
  space 
  was 
  5*0 
  cm., 
  the 
  distance 
  between 
  

   the 
  negative 
  glow 
  and 
  the 
  cathode 
  glow 
  2'2 
  cm., 
  and 
  light 
  

   from 
  the 
  first 
  centimetre 
  of 
  the 
  cathode 
  glow 
  was 
  focussed 
  

   on 
  the 
  slit. 
  After 
  20 
  hours' 
  exposure 
  with 
  a 
  cathode 
  fall 
  of 
  

   2800 
  volts, 
  a 
  marked 
  Doppler 
  effect 
  was 
  seen 
  corresponding 
  

   to 
  the 
  positive 
  rays 
  approaching 
  the 
  cathode. 
  

  

  When 
  the 
  gas 
  (hydrogen) 
  is 
  pure 
  and 
  the 
  pressure 
  not 
  too 
  

   low 
  the 
  cathode 
  glow 
  commences 
  at 
  a 
  rather 
  sharply 
  defined 
  

   surface 
  which 
  can 
  be 
  fixed 
  upon 
  with 
  reasonable 
  accuracy. 
  

   The 
  potential 
  fall 
  from 
  the 
  negative 
  glow 
  to 
  this 
  surface 
  has 
  

   been 
  compared 
  with 
  the 
  minimum 
  Doppler 
  effect, 
  i. 
  e., 
  the 
  

   distance 
  between 
  the 
  stationary 
  line 
  and 
  the 
  nearest 
  edge 
  of 
  

   the 
  shifted 
  line, 
  the 
  cathode 
  (without 
  holes) 
  being 
  viewed 
  

   from 
  the 
  anode 
  side. 
  

  

  The 
  discharge-tubes 
  had 
  a 
  diameter 
  of 
  from 
  4*5 
  to 
  4*8 
  cm. 
  

   The 
  potential 
  in 
  the 
  discharge 
  was 
  measured 
  by 
  means 
  of 
  

   sondes 
  of 
  thin 
  platinum 
  wire 
  inserted 
  at 
  right 
  angles 
  to 
  the 
  

   axis 
  of 
  the 
  tube. 
  A 
  length 
  of 
  2 
  mm. 
  was 
  exposed 
  near 
  the 
  

   axis 
  and 
  the 
  rest 
  insulated 
  by 
  means 
  of 
  fine 
  glass 
  tubing. 
  

  

  B 
  

  

  / 
  

  

  V 
  

  

  Fig. 
  1. 
  

  

  n\ 
  

  

  LJU 
  

  

  The 
  sondes 
  were 
  fixed 
  in 
  the 
  tube, 
  and 
  the 
  aluminium 
  

   cathode 
  A, 
  fitting 
  closely 
  in 
  the 
  tube, 
  could 
  be 
  made 
  to 
  

   approach 
  the 
  sondes 
  by 
  means 
  of 
  a 
  magnet 
  outside 
  the 
  tube 
  

   attracting 
  the 
  iron 
  piece 
  B 
  attached 
  to 
  the 
  cathode. 
  Tl^e 
  

   sonde 
  C 
  gave 
  the 
  potential 
  in 
  the 
  dark 
  space, 
  the 
  sonde 
  D 
  

   remaining 
  in 
  the 
  negative 
  glow 
  throughout 
  which 
  the 
  potential 
  

   is 
  practically 
  constant, 
  This 
  second 
  sonde 
  was 
  introduced 
  

   in 
  order 
  to 
  show 
  that 
  the 
  cathode 
  fall 
  was 
  not 
  altered 
  by 
  

   bringing 
  up 
  the 
  cathode. 
  The 
  anode 
  was 
  placed 
  in 
  a 
  side 
  

   tube 
  E 
  in 
  order 
  to 
  allow 
  the 
  cathode 
  to 
  be 
  seen 
  through 
  the 
  

   end 
  F 
  of 
  the 
  tube. 
  The 
  current 
  was 
  taken 
  from 
  a 
  battery 
  of 
  

   accumulators 
  with 
  a 
  maximum 
  potential 
  of 
  3000 
  volts 
  and 
  

   the 
  potential 
  measured 
  bv 
  means 
  of 
  a 
  calibrated 
  Braun 
  

  

  