﻿Wood 
  

  

  Phi. 
  Mag. 
  S. 
  6. 
  Vol 
  3. 
  PL 
  II 
  

  

  Position 
  of 
  

   undeviated 
  

   image 
  of 
  slit. 
  

  

  West, 
  Newman 
  chromo. 
  

  

  Anomalous 
  Spectrum 
  produced 
  by 
  Prism 
  of 
  Sodium 
  Vapour. 
  

  

  