﻿Investigation 
  of 
  the 
  Nature 
  0/ 
  y 
  Rays. 
  937 
  

  

  A 
  cathode 
  particle 
  cannot 
  give 
  all 
  its 
  energy 
  to 
  a 
  pulse 
  

   unless 
  its 
  arrest 
  is 
  brought 
  about 
  in 
  a 
  very 
  sudden 
  and 
  special 
  

   way. 
  The 
  thickness 
  o£ 
  the 
  pulse 
  must 
  not 
  be 
  greater 
  than 
  

   the 
  diameter 
  o£ 
  the 
  electron 
  or 
  corpuscle 
  (' 
  Cond. 
  of 
  Elect.,' 
  

   p. 
  660). 
  If 
  the 
  pulse 
  is 
  thicker 
  than 
  this, 
  only 
  a 
  propor- 
  

   tional 
  fraction 
  of 
  the 
  energy 
  of 
  the 
  cathode 
  particle 
  can 
  be 
  

   converted 
  into 
  the 
  energy 
  of 
  the 
  pulse. 
  Now 
  it 
  is 
  generally 
  

   believed 
  that 
  the 
  phenomena 
  of 
  the 
  X-rays 
  require 
  a 
  pulse 
  

   many 
  thousands 
  of 
  times 
  as 
  thick 
  as 
  the 
  diameter 
  of 
  an 
  

   electron. 
  It 
  does 
  not 
  seem 
  possible 
  to 
  reconcile 
  these 
  

   •opposite 
  requirements. 
  

  

  The 
  bundle 
  must 
  be 
  excessively 
  small. 
  If 
  it 
  is 
  larger 
  than 
  an 
  

   atom, 
  or 
  even 
  than 
  an 
  electron, 
  the 
  whole 
  of 
  its 
  energy 
  cannot 
  

   be 
  given 
  up 
  to 
  one 
  electron 
  on 
  which 
  it 
  impinges. 
  There 
  

   would 
  not 
  be 
  time 
  for 
  the 
  energy 
  to 
  move 
  in 
  from 
  the 
  outskirts 
  

   of 
  the 
  bundle 
  to 
  the 
  place 
  where 
  it 
  is 
  being 
  transformed 
  into 
  

   the 
  motion 
  of 
  the 
  electron. 
  It 
  must 
  not 
  expand 
  or 
  contract 
  its 
  

   borders 
  as 
  it 
  moves, 
  or 
  else 
  its 
  effect 
  will 
  vary 
  as 
  it 
  travels. 
  

  

  The 
  difficulties 
  of 
  this 
  theory 
  are 
  exactly 
  those 
  which 
  would 
  

   naturally 
  arise 
  in 
  the 
  attempt 
  to 
  transfer 
  the 
  properties 
  of 
  a 
  

   material 
  particle 
  to 
  an 
  immaterial 
  disturbance. 
  

  

  Let 
  us 
  now 
  consider 
  the 
  third 
  form 
  of 
  hypothesis, 
  ac- 
  

   cording 
  to 
  which 
  both 
  the 
  energy 
  and 
  the 
  material 
  of 
  the 
  

   secondary 
  electron 
  are 
  derived 
  from 
  the 
  primary 
  ray. 
  In 
  

   our 
  previous 
  paper 
  on 
  this 
  subject, 
  and 
  in 
  papers 
  on 
  " 
  The 
  

   Properties 
  and 
  Natures 
  of 
  Various 
  Electric 
  Radiations 
  " 
  

   (Trans. 
  Roy. 
  Soc. 
  of 
  S.A., 
  May 
  and 
  June, 
  1907 
  ; 
  Phil. 
  Mag. 
  

   Oct. 
  1907), 
  it 
  was 
  shown 
  that 
  the 
  hypothesis 
  offered 
  a 
  reason- 
  

   able 
  explanation 
  of 
  all 
  the 
  phenomena 
  known 
  to 
  date. 
  It 
  is 
  

   only 
  necessary 
  now 
  to 
  show 
  to 
  what 
  extent 
  it 
  fits 
  with 
  the 
  

   properties 
  of 
  the 
  y 
  rays 
  enumerated 
  in 
  § 
  II. 
  of 
  this 
  paper. 
  

   We 
  will 
  take 
  the 
  properties 
  in 
  turn. 
  

  

  As 
  regards 
  (1) 
  we 
  have 
  simply 
  to 
  suppose 
  that 
  the 
  nega- 
  

   tive 
  and 
  positive, 
  passing 
  united 
  into 
  an 
  atom, 
  are 
  separated 
  if 
  

   they 
  happen 
  to 
  traverse 
  a 
  very 
  strong 
  field 
  anywhere 
  therein 
  ; 
  

   the 
  negative 
  flies 
  on 
  and 
  the 
  positive 
  becomes 
  ineffective. 
  

  

  The 
  second 
  property 
  is 
  also 
  an 
  obvious 
  consequence 
  of 
  the 
  

   hypothesis. 
  The 
  faster 
  the 
  7 
  particle 
  is 
  moving 
  the 
  greater 
  

   the 
  initial 
  speed 
  of 
  the 
  negative. 
  

  

  The 
  third 
  is 
  readily 
  explainable 
  : 
  the 
  electric 
  field 
  of 
  the 
  

   atom 
  merely 
  dissolves 
  the 
  bonds 
  that 
  connect 
  the 
  pair. 
  It 
  is 
  

   not 
  able 
  to 
  affect 
  the 
  speed 
  of 
  the 
  negative 
  set 
  free. 
  

  

  The 
  fourth 
  may 
  be 
  taken 
  to 
  imply 
  that 
  the 
  radioactive 
  

   atom 
  (say 
  RaC) 
  ejects 
  electrons 
  at 
  certain 
  speeds, 
  some 
  of 
  

   which 
  start 
  off 
  in 
  company 
  with 
  a 
  positive 
  counterpart, 
  some 
  

   without. 
  The 
  former 
  constitute 
  the 
  y 
  rays, 
  the 
  latter 
  the 
  

  

  