﻿Striations 
  in 
  the 
  Electric 
  Discharge. 
  443 
  

  

  transition 
  from 
  positive 
  to 
  negative 
  force 
  was 
  very 
  abrupt 
  

   and 
  Avell 
  marked, 
  so 
  much 
  so 
  indeed 
  that 
  the 
  position 
  o£ 
  the 
  

  

  i^i;^. 
  1. 
  

  

  r:-44 
  

  

  III 
  \. 
  im 
  

  

  m 
  

  

  ; 
  ^J 
  

  

  •J^.. 
  Bright 
  /iiri 
  ofSCruUCon. 
  

  

  Fig. 
  2. 
  ^ 
  

  

  

  

  _.ii-. 
  

  

  - 
  'm 
  

  

  pLatinum 
  wires 
  in 
  the 
  striation 
  could 
  be 
  ascertained 
  with 
  

   great 
  accuracy 
  without 
  looking 
  at 
  the 
  discharge, 
  by 
  observing 
  

   the 
  deflexions 
  of 
  the 
  electrometer 
  by 
  which 
  the 
  potential- 
  

   difference 
  between 
  the 
  wires 
  was 
  measured. 
  

  

  Many 
  changes 
  were 
  made 
  in 
  the 
  way 
  in 
  which 
  the 
  wires 
  

   used 
  as 
  detectors 
  were 
  arranged: 
  thus, 
  to 
  prevent 
  any 
  screening 
  

   o£ 
  the 
  one 
  wire 
  by 
  the 
  other^ 
  an 
  apparatus 
  was 
  used 
  in 
  which 
  

   the 
  two 
  platinum 
  wires 
  were 
  brought 
  in 
  from 
  opposite 
  sides 
  

   of 
  the 
  tube, 
  so 
  that 
  there 
  should 
  be 
  no 
  overlapping 
  ; 
  exactly 
  

   the 
  same 
  results 
  were 
  obtained 
  with 
  this 
  apparatus 
  as 
  with 
  

   the 
  other. 
  Again, 
  another 
  arrangement, 
  similar 
  to 
  one 
  pre- 
  

   viously 
  used 
  by 
  Professor 
  H. 
  A. 
  Wilson, 
  was 
  tried, 
  in 
  which 
  

   the 
  exploring 
  electrodes 
  were 
  kept 
  fixed, 
  and 
  the 
  anode 
  and 
  

   cathode 
  kept 
  at 
  fixed 
  distance 
  apart 
  were, 
  by 
  means 
  of 
  a 
  float, 
  

   moved 
  relatively 
  to 
  the 
  exploring 
  electrodes 
  a, 
  6, 
  so 
  that 
  these 
  

   could 
  occupy 
  all 
  positions 
  from 
  the 
  anode 
  to 
  the 
  cathode. 
  

   The 
  arrangement 
  is 
  represented 
  in 
  fig. 
  3 
  (p. 
  444). 
  The 
  ex- 
  

   ploring 
  electrodes 
  in 
  some 
  of 
  the 
  experiments 
  protruded 
  about 
  

   a 
  millimetre 
  beyond 
  the 
  ends 
  of 
  the 
  glass 
  tubes 
  into 
  which 
  

   they 
  were 
  sealed 
  ; 
  in 
  other 
  experiments 
  very 
  fine 
  hollow 
  

   glass 
  tubes 
  were 
  used 
  to 
  cover 
  the 
  wires, 
  and 
  the 
  wires 
  instead 
  

   of 
  protruding 
  beyond 
  the 
  glass 
  stopped 
  short 
  at 
  about 
  a 
  

   millimetre 
  from 
  the 
  end 
  of 
  the 
  tube 
  ; 
  this 
  arrangement 
  was 
  

   adopted 
  with 
  the 
  idea 
  of 
  protecting 
  the 
  wires 
  against 
  streams 
  

   of 
  corpuscles 
  coming 
  down 
  the 
  tube: 
  these 
  by 
  giving 
  up 
  their 
  

   charges 
  to 
  the 
  wire 
  might 
  cause 
  this 
  to 
  acquire 
  potentials 
  

   different 
  from 
  those 
  of 
  the 
  gas 
  at 
  the 
  tips 
  of 
  the 
  wire. 
  The 
  

   results 
  obtained 
  with 
  all 
  these 
  modifications 
  were 
  exactly 
  the 
  

   same 
  as 
  those 
  obtained 
  with 
  the 
  first 
  type 
  of 
  apparatus, 
  i, 
  e. 
  

   there 
  was 
  al^vNavs 
  when 
  the 
  pressure 
  of 
  the 
  eras 
  was 
  low 
  a 
  

  

  2H2 
  

  

  