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  LONDON, 
  EDINBURGH, 
  and 
  DUBLIN 
  

  

  PHILOSOPHICAL 
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  r 
  

  

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  JOURNAL 
  OF 
  SCIENCE. 
  

  

  CONDUCTED 
  BY 
  

  

  SIR 
  OLIVER 
  JOSEPH 
  LODGE, 
  D.Sc., 
  LL.D, 
  F.R.S. 
  

   SIR 
  JOSEPH 
  JOHN 
  THOMSON, 
  O.M., 
  M.A., 
  Sc.D., 
  LL.D., 
  F.R.S, 
  

   JOHN 
  JOLY, 
  M.A., 
  D.Sc, 
  F.R.S, 
  F.G.3. 
  

   GEORGE 
  CAREY 
  FOSTER, 
  B.A, 
  LL.D, 
  F.R.S. 
  

  

  AND 
  

  

  WILLIAM 
  FRANCIS, 
  F.L.S. 
  

  

  "Nee 
  aranearum 
  sane 
  textus 
  ideo 
  raelior 
  quia 
  ex 
  se 
  fila 
  gignnnt, 
  nee 
  noster 
  

   vilior 
  quia 
  ex 
  alienis 
  libamus 
  ut 
  apes." 
  Just. 
  Lips. 
  Polit. 
  lib. 
  i. 
  cap. 
  l.Not. 
  

  

  VOL. 
  XXXV.— 
  SIXTH 
  SERIES, 
  

   JANUARY— 
  JUNE 
  1918. 
  

  

  LONDON: 
  

   TA7L0B, 
  AND 
  FRANCIS, 
  RED 
  LION 
  COURT, 
  FLEET 
  STREET. 
  

  

  SOLD 
  BY 
  SIMPKIN, 
  MARSHALL, 
  HAMILTON, 
  KENT, 
  AND 
  CO., 
  LD. 
  

  

  SMITH 
  AND 
  <ON, 
  GLASGOW; 
  — 
  HODGES, 
  FIGGIS, 
  AND 
  CO., 
  DUBLIN; 
  — 
  

  

  AND 
  VEUVE 
  J. 
  BOYVEAU, 
  PARIS, 
  

  

  