﻿6S4: 
  Prof. 
  0. 
  W. 
  Richardson 
  on 
  the 
  Kinetic 
  

  

  the 
  plane 
  in 
  which 
  it 
  was 
  supposed 
  to 
  lie, 
  on 
  account 
  o£ 
  the 
  

   thermal 
  expansion 
  o£ 
  the 
  platinum. 
  This 
  was 
  ultimately 
  

   quite 
  overcome 
  by 
  the 
  device 
  shown 
  (chiefly) 
  in 
  fig. 
  2. 
  One 
  

   end 
  of 
  the 
  strip 
  was 
  held 
  by 
  the 
  fixed 
  screw 
  D 
  insulated 
  

   from 
  the 
  plate 
  A 
  by 
  vulcanized 
  fibre 
  shown 
  black 
  in 
  the 
  

   figures. 
  The 
  screw" 
  E 
  w^hich 
  held 
  the 
  other 
  end 
  was 
  rigidly 
  

   fixed 
  in 
  a 
  bit 
  of 
  vulcanized 
  fibre 
  driven 
  into 
  the 
  brass 
  

   cylinder 
  G, 
  from 
  which 
  it 
  was 
  insulated 
  as 
  shown 
  by 
  the 
  

   figure. 
  This 
  cylinder 
  slid 
  with 
  a 
  pin 
  and 
  slot 
  guide 
  in 
  the 
  

   outer 
  brass 
  cylinder 
  H 
  which 
  just 
  fitted 
  it. 
  It 
  was 
  pulled 
  

   back 
  by 
  a 
  light 
  indiarabber 
  band 
  which 
  passed 
  over 
  the 
  pin 
  J. 
  

   This 
  passed 
  through 
  the 
  cylinder 
  and 
  also 
  over 
  a 
  hook 
  (not 
  

   showm) 
  attached 
  to 
  the 
  back 
  of 
  the 
  plate 
  A. 
  The 
  cylinder 
  

   could 
  be 
  pulled 
  forward 
  by 
  a 
  thread 
  passing 
  over 
  the 
  brass 
  

   rod 
  shown 
  in 
  section 
  at 
  K. 
  The 
  whole 
  of 
  this 
  part 
  of 
  the 
  

   apparatus 
  was 
  enclosed 
  in 
  a 
  wide 
  vertical 
  glass 
  tube 
  L 
  and 
  

   the 
  thread 
  passed 
  dow^n 
  a 
  horizontal 
  side 
  tube 
  M. 
  The 
  rod 
  

   K 
  passed 
  up 
  another 
  vertical 
  tube 
  N, 
  which 
  carried 
  a 
  mercury 
  

   sealed 
  ground 
  stopper 
  to 
  which 
  the 
  rod 
  K 
  was 
  rigidly 
  attached. 
  

   By 
  turning 
  the 
  stopper 
  the 
  string 
  could 
  be 
  w^ound 
  or 
  unv\ 
  ound 
  

   round 
  the 
  rod, 
  and 
  so 
  the 
  strip 
  C 
  could 
  be 
  kept 
  just 
  tight 
  

   from 
  outside 
  the 
  apparatus. 
  Whenever 
  the 
  heating 
  current 
  

   was 
  reduced 
  it 
  was 
  of 
  course 
  necessary 
  to 
  unwind 
  some 
  of 
  

   the 
  string, 
  otherwise 
  the 
  strip 
  would 
  snap 
  in 
  cooling. 
  

  

  The 
  opposite 
  plane 
  consisted 
  of 
  a 
  fixed 
  plate 
  B, 
  which 
  

   contained 
  a 
  rectangular 
  opening 
  P 
  (fig. 
  2). 
  This 
  extended 
  

   the 
  w^hole 
  length 
  of 
  the 
  plate 
  B 
  in 
  a 
  direction 
  perpendicular 
  to 
  

   the 
  section 
  in 
  fig. 
  2. 
  The 
  opening 
  contained 
  two 
  plates 
  0, 
  

   (fig. 
  1) 
  which 
  were 
  accurately 
  in 
  the 
  same 
  plane 
  and 
  flush 
  

   wdth 
  the 
  fixed 
  plate 
  B. 
  They 
  were 
  almost 
  as 
  wide 
  as 
  the 
  

   opening, 
  but 
  not 
  in 
  contact 
  with 
  it 
  at 
  any 
  point. 
  The 
  part 
  

   of 
  them 
  which 
  is 
  shown 
  in 
  fig. 
  1 
  is 
  distinguished 
  from 
  the 
  

   plate 
  B 
  by 
  shading. 
  They 
  were 
  rigidly 
  and 
  metallically 
  

   connected 
  together 
  and 
  insulated 
  from 
  the 
  plate 
  B. 
  They 
  

   were 
  supported 
  by 
  the 
  rigid 
  brass 
  carriage 
  Q 
  (both 
  figures) 
  

   which 
  w^as 
  pushed 
  by 
  the 
  screw 
  S 
  along 
  the 
  ways 
  R 
  (fig. 
  2) 
  

   w^hich 
  were 
  attached 
  to 
  the 
  fixed 
  plate. 
  The 
  edges 
  of 
  the 
  

   slit 
  between 
  the 
  plates 
  0, 
  were 
  cut 
  away 
  as 
  shown, 
  so 
  that 
  

   all 
  the 
  ions 
  which 
  passed 
  through 
  the 
  slit 
  should 
  pass 
  into 
  

   the 
  copper 
  box 
  T. 
  The 
  number 
  of 
  ions 
  reaching 
  the 
  plates 
  

   and 
  reaching 
  T 
  were 
  measured 
  simultaneously 
  in 
  the 
  manner 
  

   previously 
  described*. 
  It 
  will 
  be 
  observed 
  that 
  only 
  the 
  

   ions 
  reaching 
  the 
  middle 
  centimetre 
  of 
  the 
  plate 
  B 
  were 
  

   received 
  by 
  either 
  the 
  testing 
  plates 
  or 
  the 
  slit, 
  so 
  that 
  the 
  

   error 
  arising 
  from 
  the 
  finite 
  length 
  of 
  the 
  hot 
  strip 
  weuld 
  be 
  

   * 
  Phil. 
  Mag. 
  [6] 
  xvi. 
  p. 
  740 
  (1908). 
  

  

  