﻿Velocities 
  of 
  Delta 
  Rays, 
  247 
  

  

  be 
  captured 
  by 
  the 
  auxiliary 
  field. 
  It 
  is 
  quite 
  improbable 
  

   that 
  this 
  correction 
  can 
  amount 
  to 
  more 
  than 
  1 
  or 
  2 
  per 
  cent. 
  

   of 
  the 
  ordinates 
  of 
  Curve 
  II. 
  

  

  ;). 
  Some 
  of 
  the 
  S-rays 
  originating 
  upon 
  the 
  sides 
  of: 
  the 
  

   box-source 
  will 
  cross 
  its 
  opening 
  obliquely, 
  and 
  will 
  he 
  de- 
  

   flected, 
  so 
  as 
  to 
  strike 
  the 
  box, 
  by 
  fields 
  too 
  small 
  to 
  stop 
  

   them. 
  Thus 
  at 
  any 
  given 
  potential, 
  some 
  electrons 
  which 
  

   should 
  get 
  away 
  will 
  not 
  do 
  so, 
  and 
  the 
  ordinates 
  of 
  Curve 
  I 
  

   will 
  be 
  thereby 
  diminished. 
  But 
  the 
  number 
  thus 
  improperly 
  

   stopped 
  at 
  any 
  voltage 
  must 
  be 
  a 
  nearly, 
  or 
  quite, 
  constant 
  

   fraction 
  of 
  those 
  which 
  should 
  escape, 
  so 
  that 
  the 
  effect 
  would 
  

   be 
  merely 
  to 
  change 
  the 
  scale 
  of 
  the 
  curve. 
  

  

  We 
  may 
  reasonably 
  conclude, 
  I 
  think, 
  that 
  the 
  measure- 
  

   ments 
  given 
  represent 
  a 
  fair 
  first 
  approximation 
  to 
  the 
  dis- 
  

   tribution 
  in 
  velocity 
  of 
  the 
  swifter 
  S-rays. 
  It 
  will 
  probably 
  

   be 
  possible 
  to 
  improve 
  the 
  accuracy 
  of 
  the 
  determination 
  by 
  

   using 
  a 
  more 
  intense 
  source 
  of 
  a-rays 
  and 
  receiving 
  a 
  

   restricted 
  beam 
  of 
  8-rays 
  in 
  a 
  Faraday 
  cylinder. 
  A 
  suitable 
  

   source 
  of 
  a-rays 
  for 
  this 
  method 
  is 
  not 
  at 
  present 
  at 
  my 
  

   disposal. 
  

  

  §6. 
  

  

  The 
  preceding 
  measurements 
  have 
  had 
  to 
  do 
  only 
  witli 
  

   S-ravs 
  whose 
  velocities 
  exceeded 
  20 
  volts. 
  By 
  reducing 
  the 
  

   sensitiveness 
  of 
  the 
  electroscope 
  to 
  somewhat 
  less 
  than 
  one- 
  

   eighth 
  of 
  its 
  former 
  value, 
  measurements 
  could 
  be 
  taken 
  with 
  

   smaller 
  negative 
  potentials 
  on 
  the 
  gauze 
  cage. 
  A 
  series 
  of 
  ob- 
  

   servations 
  made 
  in 
  this 
  manner 
  is 
  represented 
  in 
  fig. 
  5 
  (p. 
  248) 
  . 
  

   It 
  is 
  within 
  this 
  region 
  that 
  all 
  previous 
  measurements 
  of 
  

   the 
  velocities 
  of 
  S-rays 
  have 
  been, 
  so 
  far 
  as 
  I 
  know, 
  confined. 
  

   Most, 
  if 
  not 
  all, 
  of 
  such 
  measurements 
  have 
  been, 
  I 
  believe, 
  

   to 
  a 
  considerable 
  extent 
  vitiated 
  by 
  two 
  circumstances: 
  lack 
  

   of 
  knowledge 
  of 
  the 
  existence 
  of 
  the 
  swifter 
  rays 
  and 
  of 
  the 
  

   tertiary 
  rays 
  which 
  they 
  produce; 
  and 
  the 
  fact 
  that 
  the 
  a-rays 
  

   were 
  allowed 
  to 
  pass 
  through 
  the 
  field, 
  thus 
  giving 
  two 
  

   sources 
  of 
  S-rays, 
  and 
  of 
  tertiary 
  rays, 
  with 
  much 
  consequent 
  

   confusion 
  of 
  the 
  results. 
  

  

  Among 
  neither 
  the 
  swifter, 
  nor 
  the 
  slower, 
  rays 
  is 
  there 
  

   any 
  approach 
  to 
  the 
  Maxwellian 
  exponential 
  distribution 
  ; 
  if 
  

   it 
  were 
  so, 
  the 
  integrated 
  curves 
  (those 
  of 
  figs. 
  3, 
  4, 
  and 
  ;"> 
  ) 
  

   would 
  also 
  be 
  exponential. 
  This 
  is 
  not 
  true 
  in 
  either 
  case 
  : 
  

  

  * 
  In 
  the 
  curves 
  of 
  figs. 
  3 
  and 
  4 
  allowance 
  must 
  be 
  made 
  for 
  the 
  

   depression 
  of 
  the 
  zero 
  line 
  ; 
  but 
  no 
  reasonable 
  adjustment 
  of 
  this 
  sort 
  

   wiil 
  bring 
  the 
  curves 
  near 
  to 
  an 
  exponential 
  form. 
  

  

  