Vol. 33. 



APRIL 1867. 



No. 223. 



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



THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE, 



AND 



JOURNAL OF SCIENCE. 



Being a Continuation of Tilloctis Philosophical Magazine, 9 

 Nicholson's 'Journal,' and Thomson's ( Annals of Philosophy.' 



CONDUCTED BY 



SIR DAVID BREWSTER, K.H. LL.D. F.R.S. L.&E. &c, 

 SIR ROBERT KANE, M.D. F.R.S. M.R.I.A. 

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



FOURTH SERIES 



N° 223.— APRIL 1867. 



LONDON: 



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



Printers and Publishers to the University of London. 



Sold by Longmans, Gfreen, Eeader and Dyer ; Kent and Co. ; Simpkin, Marshall and 

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