﻿Phil. 
  Mag. 
  Ser. 
  6, 
  Vol. 
  16. 
  PI. 
  XVII. 
  

  

  v 
  

  

  490 
  ~. 
  

  

  959 
  

  

  iwmwf 
  UHWMtif 
  ' 
  ! 
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  Wfmf--' 
  ' 
  : 
  ;;;;.-.v.'aW 
  ■■••-' 
  **/ 
  

  

  2880 
  — 
  . 
  

   Single 
  action 
  circuit 
  waves. 
  

  

  k 
  

  

  