﻿556 
  Mr. 
  K. 
  T. 
  Compton 
  and 
  Prof. 
  0. 
  W. 
  Richardson 
  on 
  

  

  The 
  Photoelectric 
  Measurements. 
  

  

  The 
  apparatus 
  which 
  we 
  found 
  most 
  satisfactory 
  for 
  

   making 
  the 
  photoelectric 
  measurements 
  is 
  illustrated 
  in 
  

   fig. 
  2. 
  It 
  is 
  similar 
  to 
  that 
  used 
  in 
  our 
  previous 
  experiments 
  

  

  Pier. 
  2, 
  

  

  on 
  electron 
  velocities, 
  with 
  the 
  addition 
  of 
  arrangements 
  

   designed 
  to 
  make 
  possible 
  a 
  more 
  perfect 
  vacuum 
  and 
  to 
  

   give 
  an 
  absolutely 
  clean, 
  untarnished 
  metal 
  strip 
  upon 
  which 
  

   to 
  focus 
  the 
  light 
  from 
  the 
  spectrometer-slit. 
  Light 
  from 
  the 
  

  

  