Vol. 30. 



OCTOBER 1865. 



No. 203. 



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 Tilloch's 'Philosophical Magazine, 9 

 Nicholson's 'Journal 9 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° 203.— OCTOBER 1865. 



LONDON: 



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



Printers and Publishers to the University of London. 



Sold by Longman, Green, Longmans, nd Roberts; Piper and Co.; Simpkin, 

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 Hodges and Smith, Dublin: — and Putnam, New York. 



