Pol. 39. MAY 1870. No. 262. 



Published the First Day of every Month.— Price 2s. 6rf. 



THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE, 



AND 



JOURNAL OF SCIENCE. 



Being a Continuation of TillocfCs 'Philosophical Magazine,' 

 Nicholson 9 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. 

 AUGUSTUS MATTHIESSEN, Ph.D. F.R.S. F.C.S. 



AND 



WILLIAM FRANCIS, Ph.D. F.L.S. F.R.A.S. F.C.S. 



FOURTH SERIES 



N° 262.— MAY 1870. 



LONDON: 



PBINTED BY TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET, 

 Printers and Publishers to the University of London. 



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