﻿Ionization 
  and 
  Wireless 
  Telegraphy 
  . 
  

  

  575 
  

  

  similar 
  set 
  of 
  readings 
  was 
  then 
  taken 
  when 
  the 
  air 
  between 
  

   the 
  plates 
  of 
  the 
  condenser 
  was 
  ionized. 
  The 
  curves 
  showing 
  

   the 
  shift 
  of 
  the 
  peak 
  for 
  one 
  case 
  are 
  given 
  in 
  fig. 
  6. 
  

  

  -Fig 
  1 
  . 
  6. 
  — 
  Shift 
  of 
  Resonance 
  Peak 
  due 
  to 
  Ionization. 
  

  

  mm. 
  

  

  3001- 
  

  

  280 
  

   ^250 
  

   S240 
  

  

  

  20C 
  

  

  ISO- 
  

  

  , 
  t 
  ,T 
  

  

  70 
  

  

  7! 
  72 
  75cm. 
  

  

  Cymometer 
  Scale. 
  

  

  The 
  two 
  induction-coils 
  used 
  were 
  each 
  placed 
  on 
  end 
  (see 
  

   figs. 
  4, 
  p. 
  573, 
  and 
  7, 
  PI. 
  XI.), 
  as 
  it 
  was 
  observed 
  that 
  in 
  the 
  

   ordinary 
  position 
  their 
  magnetic 
  fields 
  affected 
  the 
  magneti- 
  

   cally 
  controlled 
  electrometer-needle. 
  To 
  shield 
  the 
  zinc-plate 
  

   condenser 
  from 
  the 
  effects 
  due 
  to 
  the 
  field 
  across 
  the 
  X-ray 
  

   tube, 
  an 
  earth-connected 
  lead 
  plate 
  was 
  placed 
  below 
  the 
  bulb 
  

   and 
  at 
  a 
  height 
  of 
  22 
  cm. 
  above 
  the 
  zinc 
  plates. 
  The 
  lead 
  screen 
  

   had 
  in 
  the 
  middle 
  an 
  opening 
  10 
  cm. 
  square, 
  on 
  which 
  could 
  

   be 
  placed 
  piles 
  of 
  aluminium 
  plates 
  of 
  varying 
  thicknesses. 
  

   The 
  5 
  mg. 
  of 
  radium 
  bromide, 
  when 
  used 
  for 
  ionization, 
  was 
  

   placed 
  about 
  5 
  cm. 
  above 
  the 
  level 
  of 
  the 
  lead 
  screen. 
  More- 
  

   over, 
  to 
  guard 
  against 
  dust 
  and 
  air-currents, 
  the 
  wooden 
  

   framework 
  supporting 
  the 
  earthed 
  plate 
  was 
  enclosed 
  on 
  

   three 
  sides 
  with 
  cardboard, 
  one 
  portion 
  of 
  which 
  was 
  re- 
  

   moved 
  when 
  taking 
  the 
  photograph 
  reproduced 
  in 
  fig. 
  7 
  

   (PI. 
  XI.). 
  A 
  Lodge 
  valve 
  V 
  (fig. 
  4) 
  was 
  used 
  in 
  connexion 
  

   with 
  the 
  X-ray 
  tube 
  to 
  assist 
  in 
  ensuring 
  that 
  the 
  discharge 
  

   w 
  T 
  as 
  unidirectional. 
  

  

  Results. 
  

  

  The 
  results 
  given 
  in 
  the 
  accompanying 
  table 
  show 
  in 
  each 
  

   case 
  the 
  shift 
  of 
  the 
  resonance 
  peak 
  necessary 
  to 
  compensate 
  

   for 
  the 
  change 
  in 
  frequency 
  of 
  the 
  responding 
  circuit 
  when 
  

  

  