﻿1018 
  Dr. 
  R. 
  Pohl 
  and 
  Dr. 
  P. 
  Prinffsheim 
  on 
  the 
  

  

  jo 
  

  

  Joffe 
  *, 
  somewhat 
  later, 
  pointed 
  out 
  that 
  the 
  values 
  for 
  

   the 
  photoelectric 
  initial 
  velocities 
  published 
  by 
  E. 
  Ladenburgt 
  

   in 
  1907 
  could 
  be 
  just 
  as 
  well 
  represented 
  by 
  Einstein's 
  

   formula 
  as 
  by 
  the 
  formula 
  originally 
  adopted 
  by 
  Ladenburg, 
  

   according 
  to 
  which 
  the 
  velocity 
  itself 
  and 
  not 
  the 
  square 
  of 
  

   the 
  velocity 
  is 
  proportional 
  to 
  the 
  frequency. 
  Since 
  thnt 
  

   time 
  a 
  great 
  many 
  papers 
  have 
  appeared 
  in 
  which 
  this 
  

   question 
  of 
  proportionality 
  was 
  thought 
  to 
  have 
  been 
  

   conclusively 
  settled. 
  In 
  our 
  opinion, 
  however, 
  no 
  great 
  

   advance 
  in 
  this 
  direction 
  has 
  been 
  made 
  over 
  the 
  results 
  of 
  

   Joffe 
  and 
  of 
  Ladenburg. 
  As 
  an 
  instance 
  of 
  the 
  uncertainty, 
  

   Mr. 
  Kunz 
  at 
  first 
  believed 
  his 
  measurements 
  verified 
  Ein- 
  

   stein's 
  formula 
  %, 
  but 
  later, 
  on 
  the 
  basis 
  of 
  a 
  theory 
  of 
  his 
  

   own, 
  proposed 
  a 
  relation 
  according 
  to 
  which 
  P 
  increased 
  

   proportionally 
  to 
  v 
  2 
  , 
  and 
  also 
  verified 
  this 
  relation 
  experi- 
  

   mentally 
  §. 
  Actually, 
  though, 
  his 
  results 
  may 
  be 
  equally 
  

   well 
  represented 
  by 
  either 
  formula. 
  Indeed, 
  as 
  Compton 
  || 
  

   has 
  recently 
  pointed 
  out, 
  the 
  values 
  obtained 
  by 
  Kunz's 
  pupil 
  

   Cornelius 
  T 
  for 
  Cs 
  and 
  K 
  correspond 
  even 
  better 
  to 
  a 
  pro- 
  

   portionality 
  of 
  P 
  with 
  v 
  3 
  . 
  Nor 
  do 
  the 
  results 
  which 
  

   Richardson 
  & 
  Compton 
  ** 
  in 
  their 
  joint 
  paper 
  give 
  for, 
  say, 
  

   Al 
  lead 
  in 
  our 
  opinion 
  to 
  a 
  definite 
  conclusion. 
  As 
  curves 
  

   1 
  and 
  2, 
  fig. 
  1, 
  show, 
  they 
  mav 
  be 
  represented 
  with 
  approxi- 
  

   mately 
  the 
  same 
  accuracy 
  either 
  by 
  a 
  linear 
  or 
  by 
  a 
  quad- 
  

   ratic 
  relationf 
  f. 
  In 
  particular 
  the 
  accuracy 
  of 
  the 
  value 
  for 
  

   \ 
  = 
  200fXfju, 
  which 
  would 
  perhaps 
  speak 
  more 
  for 
  the 
  linear 
  

   relation, 
  cannot 
  be 
  very 
  great 
  on 
  account 
  of 
  the 
  very 
  small 
  

   energy 
  of 
  the 
  radiation 
  from 
  a 
  quartz-Hg 
  lamp 
  in 
  this 
  

   region 
  of 
  the 
  spectrum. 
  This 
  same 
  criticism 
  applies 
  in 
  an 
  

   even 
  greater 
  measure 
  to 
  the 
  measurements 
  of 
  Hughes 
  Jf 
  on 
  

   Cd, 
  which 
  are 
  plotted 
  as 
  curves 
  3 
  and 
  4, 
  fig. 
  1, 
  and 
  in 
  which 
  

   the 
  point 
  corresponding 
  to 
  \ 
  = 
  185 
  fjifju 
  §§ 
  would 
  seem 
  to 
  

  

  * 
  A. 
  Joffe, 
  Ann. 
  d. 
  Phys. 
  xxiv. 
  p. 
  939 
  (1907). 
  

  

  T 
  E. 
  Ladenburg, 
  Verh. 
  d. 
  D. 
  Phys. 
  Ges. 
  ix. 
  p. 
  504 
  (1907). 
  

  

  t 
  I. 
  Kunz, 
  Phys. 
  Rev. 
  xxix. 
  p. 
  212 
  (1909). 
  

  

  $ 
  I. 
  Kunz, 
  Phvs. 
  Rev. 
  xxxiii. 
  p. 
  208 
  (1911). 
  

  

  j| 
  K. 
  T. 
  Compton, 
  Phvs. 
  Rev. 
  [2] 
  i. 
  p. 
  382 
  (1913). 
  

  

  51 
  D. 
  W. 
  Cornelius, 
  Phvs. 
  Rev. 
  [2] 
  i. 
  p. 
  16 
  (1913). 
  

  

  ** 
  O. 
  Richardson 
  & 
  K. 
  T. 
  Compton, 
  Phil. 
  Mag. 
  [6] 
  xxiv. 
  p. 
  575(1912). 
  

  

  tt 
  It 
  m 
  ^y 
  he 
  mentioned 
  that 
  the 
  values 
  given 
  by 
  Richardson 
  and 
  

   Compton 
  are 
  even 
  in 
  far 
  better 
  agreement 
  with 
  the 
  formula 
  

   P 
  = 
  const, 
  log 
  v 
  —p. 
  

  

  tt 
  A. 
  LI. 
  Hughes, 
  Phil. 
  Trans. 
  Roy. 
  Soc. 
  London, 
  A. 
  ccxii. 
  p. 
  205 
  

   (1912). 
  

  

  §§ 
  It 
  may 
  here 
  be 
  noted 
  that 
  the 
  Fig 
  line 
  \ 
  = 
  185ju/z, 
  whose 
  discovery 
  

   Mr. 
  Hughes 
  describes 
  in 
  Proc. 
  Camb. 
  Phil. 
  Soc. 
  xvi. 
  p. 
  428 
  (1912), 
  had 
  

   been 
  already 
  reported 
  in 
  1909 
  by 
  Fritz 
  Handke 
  in 
  his 
  Berliner 
  Dis- 
  

   sertation; 
  and 
  by 
  Th. 
  Lyman, 
  Astrophys. 
  Journ. 
  xxxiii. 
  p. 
  106 
  (1911). 
  

  

  