L 
JUNE   1872.  No.  288. 
Published  the  First  Day  of  every  Month. — Price  2s.  Qd. 
THE 
LONDON,  EDINBURGH,  and  DUBLIN 
PHILOSOPHICAL     MAGAZINE, 
AND 
I  JOURNAL  OF  SCIENCE. 
k    Being   a    Continuation   of  Tilloch's    l Philosophical    Magazine' 
Nicholson's  'Journal/  and  Thomson's  ' Annals  of  Philosophy' 
CONDUCTED  BY 
SIR  ROBERT  KANE,  LL.D.  F.R.S.  M.R.I.A.  F.C.S. 
SIR  WILLIAM  THOMSON,  Knt.  LL.D.  F.R.S.  &c. 
AND 
WILLIAM  FRANCIS,  Ph.D.  F.L.S.  F.R.A.S.  F.C.S. 
FOURTH    SERIES. 
N°  288.— JUNE  1872.  JW 
A  Supplement,  containing  Title,  Contents,  and  Index-,  &c.  &c.  to  the 
present  Volume,  will  be  published  with  the  Number  for  July. 
LONDON: 
PBINTED  BY  TAYLOB  AND  FBANCI8,  BED  LION  COURT,  FLEET  STBEET, 
Printers  and  Publishers  to  the  University  of  London. 
SBold  by  Longmans,  Green,  Reader  and  Dyer ;   Kent  and  Co. ;    Simpkin,  Marshall  and 
i     Co. ;  and  Whittaker  and  Co. ; — and  by  A.  and  C.  Black,  and  Thomas  Clark,  Edin- 
burgh ;  Smith  and  Son,  Glasgow: — Hodges,  Foster,  and  Co.,  Dublin: — Putnam 
New  York  : — and  Asher  and  Co.,  Berlin. 
