﻿30 
  Mr. 
  R. 
  Tabor 
  Lattey 
  on 
  the 
  

  

  In 
  calculating 
  the 
  means 
  the 
  individual 
  values 
  have 
  been 
  

   weighted 
  according 
  to 
  three 
  factors 
  : 
  

  

  (i.) 
  The 
  error 
  caused 
  by 
  5 
  sees, 
  in 
  the 
  time 
  to 
  fall 
  1 
  cm., 
  

   (ii.) 
  The 
  error 
  o£ 
  1 
  volt 
  per 
  cm. 
  in 
  the 
  value 
  of 
  X, 
  and 
  

   (iii.) 
  The 
  number 
  of 
  observations 
  on 
  which 
  V 
  depends. 
  

  

  It 
  will 
  be 
  observed 
  that 
  the 
  values 
  of 
  E 
  group 
  themselves 
  

   about 
  three 
  values, 
  indicating 
  that 
  the 
  positively 
  and 
  nega- 
  

   tively 
  charged 
  groups 
  of 
  particles 
  are 
  each 
  subdivided 
  into 
  

   sets 
  of 
  particles 
  carrying 
  charges 
  of 
  differing 
  magnitude. 
  

   Which 
  set 
  of 
  particles 
  would 
  be 
  observed 
  in 
  any 
  given 
  

   experiment 
  was 
  apparently 
  a 
  matter 
  of 
  chance. 
  Alterations 
  

   in 
  the 
  method 
  of 
  illumination 
  apparently 
  caused 
  one 
  set 
  to 
  

   show 
  up 
  rather 
  than 
  another 
  ; 
  but 
  unfortunately 
  the 
  rela- 
  

   tionship 
  between 
  the 
  conditions 
  of 
  illumination 
  and 
  the 
  

   portion 
  of 
  the 
  fog 
  observed 
  could 
  not 
  be 
  elucidated. 
  That 
  

   the 
  different 
  sets 
  of 
  particles 
  differed 
  only 
  in 
  charge 
  and 
  not 
  

   in 
  magnitude 
  was 
  shown 
  by 
  the 
  constancy 
  of 
  the 
  rate 
  of 
  fall 
  

   under 
  the 
  influence 
  of 
  gravity 
  alone. 
  

  

  In 
  the 
  case 
  of 
  the 
  fog 
  nuclei 
  produced 
  by 
  Rontgen 
  rays. 
  

   Prof. 
  H. 
  A. 
  Wilson 
  was 
  able 
  to 
  observe 
  three 
  sets 
  of 
  particles 
  

   which 
  fell 
  at 
  different 
  rates 
  under 
  the 
  influence 
  of 
  an 
  electric 
  

   field, 
  and 
  he 
  concluded 
  that 
  the 
  charges 
  on 
  the 
  more 
  highly 
  

   electrified 
  particles 
  were 
  multiples 
  of 
  those 
  on 
  the 
  particles 
  

   on 
  which 
  most 
  of 
  his 
  observations 
  were 
  made. 
  

  

  If 
  we 
  assume 
  that 
  this 
  is 
  also 
  the 
  case 
  for 
  the 
  particles 
  in 
  an 
  

   electrolytic 
  fog, 
  we 
  obtain 
  as 
  the 
  mean 
  weighted 
  submultiple 
  

   ■i'66 
  X 
  10-10, 
  and 
  the 
  final 
  mean 
  values 
  of 
  E 
  X 
  10^^ 
  will 
  be 
  

  

  4-66 
  9-33 
  and 
  18-66. 
  

  

  Rutherford 
  and 
  Geiger 
  * 
  obtained 
  9*3 
  X 
  10 
  "^^ 
  for 
  the 
  value 
  

   of 
  the 
  charge 
  on 
  an 
  a-particle, 
  and 
  as 
  they 
  consider 
  that 
  an 
  

   a-particle 
  probably 
  has 
  two 
  atomic 
  charges, 
  they 
  give 
  

   4*65 
  X 
  10~io 
  as 
  the 
  value 
  of 
  unit 
  atomic 
  charge 
  in 
  E,S. 
  units. 
  

  

  The 
  values 
  obtained 
  by 
  observation 
  of 
  the 
  rate 
  of 
  fall 
  of 
  an 
  

   expansion 
  fog 
  in 
  gases 
  ionized 
  by 
  various 
  methods 
  vary 
  some- 
  

   w^hat, 
  but 
  are 
  all 
  of 
  the 
  same 
  order 
  of 
  magnitude. 
  

  

  6-5 
  Xl0-i<^ 
  J.J.Thomson. 
  Phil. 
  Mag. 
  [5] 
  xlvi. 
  1898, 
  p. 
  528; 
  

   6-8 
  X 
  10-10 
  „ 
  „ 
  [5] 
  xlviii. 
  1899; 
  

  

  .3-4 
  XIO-^^ 
  „ 
  „ 
  [6]v. 
  1903, 
  p. 
  352; 
  

  

  3-1 
  X 
  10-10 
  H. 
  A. 
  Wilson. 
  „ 
  [6] 
  v. 
  1903, 
  p. 
  429. 
  

  

  4-06 
  X 
  10-10 
  Milikan 
  & 
  Phys. 
  Rev. 
  1908, 
  p. 
  197. 
  

   Begeman. 
  

  

  * 
  Proc. 
  Roy. 
  Soc. 
  kxxi.A, 
  1908, 
  p. 
  169. 
  

  

  