﻿550 
  Mr. 
  K. 
  T. 
  Oompton 
  and 
  Prof. 
  0. 
  W. 
  Richardson 
  on 
  

  

  Recent 
  work 
  by 
  the 
  writers 
  * 
  and 
  by 
  Hughes 
  f 
  has 
  well 
  

   established 
  the 
  fact 
  that 
  there 
  is 
  a 
  linear 
  relation 
  between 
  

   the 
  maximum 
  initial 
  kinetic 
  energy 
  of 
  the 
  emitted 
  electrons 
  

   and 
  the 
  frequency 
  of 
  the 
  incident 
  light. 
  This 
  relation 
  has 
  

   been 
  suggested 
  before, 
  but 
  secondary 
  effects 
  clue 
  to 
  reflected 
  

   light 
  and 
  reflected 
  electrons, 
  to 
  impurity 
  of 
  the 
  spectrum, 
  

   and 
  several 
  other 
  factors 
  have 
  rendered 
  the 
  experimental 
  

   proofs 
  of 
  this 
  relation 
  uncertain 
  and 
  contradictory. 
  The 
  

   relation 
  may 
  be 
  expressed 
  by 
  the 
  formula 
  

  

  where 
  Y 
  is 
  the 
  maximum 
  initial 
  kinetic 
  energy 
  of 
  the 
  liberated 
  

   electrons, 
  expressed 
  in 
  equivalent 
  volts, 
  k 
  and 
  ic 
  are 
  constants, 
  

   and 
  v 
  is 
  the 
  frequency 
  of 
  the 
  incident 
  light. 
  The 
  average 
  

   value 
  of 
  k 
  for 
  eight 
  different 
  metals 
  we 
  found 
  to 
  be 
  

  

  k 
  = 
  5"-4 
  10~ 
  27 
  erg 
  sec, 
  

  

  while 
  Huodies 
  found 
  

  

  r> 
  

  

  - 
  D'6 
  10 
  M 
  erg 
  sec. 
  

   e 
  

  

  to 
  

  

  as 
  the 
  average 
  for 
  a 
  number 
  of 
  metals. 
  w 
  is 
  the 
  work, 
  

   expressed 
  in 
  equivalent 
  volts, 
  done 
  by 
  an 
  electron 
  in 
  escaping 
  

   from 
  the 
  metal. 
  Our 
  work 
  showed 
  that, 
  within 
  the 
  limits 
  of 
  

   experimental 
  error, 
  w 
  for 
  any 
  metal 
  has 
  a 
  value 
  which 
  may 
  

   be 
  calculated 
  independently 
  from 
  a 
  direct 
  knowledge 
  of 
  iv 
  

   for 
  platinum 
  and 
  the 
  contact 
  difference 
  of 
  potential 
  between 
  

   platinum 
  and 
  the 
  given 
  metal. 
  

  

  These 
  experimental 
  results 
  confirm 
  the 
  theory 
  of 
  photo- 
  

   electric 
  action 
  which 
  was 
  recently 
  developed 
  by 
  one 
  of 
  the 
  

   writers 
  if. 
  By 
  thermodynamic 
  and 
  statistical 
  methods 
  the 
  

   conclusion 
  was 
  reached 
  that 
  the 
  relation 
  between 
  velocity 
  and 
  

   frequency 
  should 
  be 
  given 
  by 
  the 
  equation 
  § 
  

  

  v 
  300 
  / 
  n\ 
  

  

  where 
  h 
  is 
  Planck's 
  constant, 
  6' 
  55 
  10 
  ~ 
  27 
  erg 
  sec. 
  The 
  

  

  * 
  Phil. 
  Mag. 
  vol.xxiv.p. 
  575 
  (1912). 
  

  

  t 
  Phil. 
  Trans. 
  Roy. 
  Soc. 
  London, 
  A. 
  vol. 
  ccxii. 
  p. 
  205 
  (1912). 
  

  

  t 
  O. 
  W. 
  Richardson, 
  Phys. 
  Rev. 
  vol. 
  xxxiv.p. 
  119(1912) 
  ; 
  Phil. 
  Mag. 
  

   vol. 
  xxiii. 
  p. 
  615 
  (1912) 
  ; 
  vol. 
  xxiv. 
  p. 
  570 
  (1912) 
  ; 
  Science, 
  vcl. 
  xxxvi. 
  

  

  ' 
  S 
  The 
  factor 
  — 
  appears 
  throughout 
  this 
  paper 
  because 
  the 
  practical 
  

  

  system 
  of 
  electrical 
  units 
  is 
  employed. 
  

  

  