﻿20 
  Prof. 
  H. 
  Nagaoka 
  on 
  the 
  Diffraction 
  Phenomena 
  in 
  the 
  .7 
  

  

  centre 
  of 
  a 
  circular 
  disk 
  is 
  nearly 
  equal 
  to 
  1, 
  when 
  the 
  

   diameter 
  is 
  tolerably 
  large, 
  and 
  at 
  the 
  rim, 
  nearly 
  equal 
  

  

  y 
  

  

  Fig. 
  8. 
  

   ^ 
  2 
  l 
  & 
  2£'Vl-F?in 
  2 
  d>I 
  

  

  o 
  

  

  , 
  2 
  _4 
  a(g-g) 
  £ 
  

  

  * 
  ~ 
  (2a-df 
  2a-d' 
  

  

  Figr. 
  9. 
  

  

  —3 
  

  

  to 
  half 
  the 
  intensity 
  at 
  the 
  centre. 
  As 
  will 
  be 
  seen 
  from 
  the 
  

   expression 
  for 
  T 
  i? 
  the 
  intensity 
  increases 
  very 
  rapidly 
  from 
  

  

  