Pol. 39. JUNE 1870. No. 263. 



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



THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE, 



AND 



JOURNAL OF SCIENCE. 



Being a Continuation of TillocWs ' Philosophical Magazine, 9 

 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. 

 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° 263.— JUNE 1870. 



_ 



LONDON: 



PRINTED BY TAYLOR AND FRANCIS, RED LION COURT, ELEET STBEET, 



Printers and Publishers to the University of London. 



Sold by Longmans, Green, Reader and Dyer ; Kent and Co. ; Simpkin, Marshall and 

 Co. ; Whittaker and Co. ; andH. Bailliere, London :— and by A. and C. Black, and 

 Thomas Clark, Edinburgh; Smith and Son, Glasgow: — Hodges and Smith, 

 Dublin : — Putnam, New York : — and Asher and Co., Berlin. 



