﻿502 
  Mr. 
  R. 
  V. 
  Southwell 
  on 
  the 
  

  

  nature 
  of 
  the 
  particles 
  emitted. 
  The 
  results 
  of 
  experiments 
  

   are 
  expressed 
  in 
  the 
  two 
  rules 
  * 
  : 
  — 
  

  

  1. 
  Whenever 
  an 
  a-particle 
  is 
  expelled 
  the 
  group 
  in 
  the 
  

   periodic 
  system 
  to 
  which 
  the 
  resultant 
  product 
  belongs 
  is 
  two 
  

   units 
  less 
  than 
  that 
  to 
  which 
  the 
  parent 
  body 
  belongs. 
  

  

  2. 
  Whenever 
  a 
  /3-particle 
  is 
  expelled, 
  the 
  group 
  of 
  the 
  

   resultant 
  body 
  is 
  1 
  unit 
  greater 
  than 
  that 
  of 
  the 
  parent. 
  

  

  As 
  will 
  be 
  seen 
  this 
  is 
  exactly 
  what 
  is 
  to 
  be 
  expected 
  

   according 
  to 
  the 
  considerations 
  of 
  § 
  4. 
  

  

  In 
  escaping 
  from 
  the 
  nucleus, 
  the 
  /3-rays 
  may 
  be 
  expected 
  

   to 
  collide 
  with 
  the 
  bound 
  electrons 
  in 
  the 
  inner 
  rings. 
  This 
  

   will 
  give 
  rise 
  to 
  an 
  emission 
  of 
  a 
  characteristic 
  radiation 
  of 
  

   the 
  same 
  type 
  as 
  tbe 
  characteristic 
  Rontgen 
  radiation 
  emitted 
  

   from 
  elements 
  of 
  lower 
  atomic 
  weight 
  by 
  impact 
  of 
  cathode- 
  

   rays. 
  Tbe 
  assumption 
  that 
  the 
  emission 
  of 
  7-rays 
  is 
  due 
  to 
  

   collisions 
  of 
  /3-rays 
  with 
  bound 
  electrons 
  is 
  proposed 
  by 
  

   Rutherford 
  f 
  in 
  order 
  to 
  account 
  for 
  the 
  numerous 
  groups 
  

   of 
  homogeneous 
  /S-rays 
  expelled 
  from 
  certain 
  radioactive 
  

   substances. 
  

  

  In 
  the 
  present 
  paper 
  it 
  has 
  been 
  attempted 
  to 
  show 
  that 
  

   the 
  application 
  of 
  Planck's 
  theory 
  of 
  radiation 
  to 
  Ruther- 
  

   ford's 
  atom-model 
  through 
  the 
  introduction 
  of 
  the 
  hypothesis 
  

   of 
  the 
  universal 
  constancy 
  of 
  the 
  angular 
  momentum 
  of 
  the 
  

   bound 
  electrons, 
  leads 
  to 
  results 
  which 
  seem 
  to 
  be 
  in 
  agreement 
  

   with 
  experiments. 
  

  

  In 
  a 
  later 
  paper 
  the 
  theory 
  will 
  be 
  applied 
  to 
  systems 
  

   containing 
  more 
  than 
  one 
  nucleus. 
  

  

  XXXVIII. 
  On 
  the 
  Collapse 
  of 
  lubes 
  by 
  External 
  Pressure. 
  

   — 
  II. 
  By 
  R. 
  V. 
  Southwell, 
  B.A., 
  Fellow 
  of 
  Trinity 
  

   College, 
  Cambridge 
  %. 
  

  

  IX 
  the 
  issue 
  of 
  this 
  Magazine 
  for 
  May 
  1913 
  § 
  I 
  have 
  dealt 
  

   with 
  the 
  effects 
  of 
  circular 
  ends 
  upon 
  the 
  resistance 
  of 
  

   tubes 
  to 
  collapse 
  by 
  external 
  pressure, 
  and 
  in 
  a 
  somewhat 
  

   fuller 
  discussion 
  of 
  the 
  same 
  problem 
  || 
  I 
  have 
  shown 
  that 
  

   my 
  results 
  are 
  well 
  supported 
  by 
  experiment, 
  so 
  far 
  as 
  the 
  

  

  * 
  See 
  A. 
  S. 
  Russell, 
  Chem. 
  News, 
  cvii. 
  p. 
  49 
  (1913) 
  ; 
  G. 
  v. 
  Hevesy, 
  

   Phys. 
  Zeitschr. 
  xiv. 
  p. 
  49 
  (1913) 
  ; 
  K. 
  Fajans, 
  Phys. 
  Zeitschr. 
  xiv. 
  pp. 
  131 
  

   & 
  136 
  (1913) 
  : 
  Verh. 
  d. 
  deutsch. 
  Phys. 
  Ges. 
  xv. 
  p. 
  240 
  (1913) 
  ; 
  E. 
  Soddj, 
  

   Chem. 
  News, 
  cvii. 
  p. 
  97 
  (1913). 
  

  

  t 
  E. 
  Rutherford, 
  Phil. 
  Mag. 
  xxiv. 
  pp. 
  453 
  & 
  893 
  (1912). 
  

  

  X 
  Communicated 
  by 
  the 
  Author. 
  

  

  § 
  Vol. 
  xxv. 
  pp. 
  687-698. 
  

  

  !| 
  "On 
  the 
  General 
  Theory 
  of 
  Elastic 
  Stability," 
  Phil. 
  Trans. 
  Roy. 
  

   Soc. 
  A. 
  vol. 
  ccxiii. 
  pp. 
  187-244 
  (1913). 
  

  

  