Vol. 30. JULY 1865. No. 200, 



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 6 Philosophical Magazine, 9 

 Nicholson's 'Journal' and Thomson's 'Annals of Philosophy ' 



CONDUCTED ltY 



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° 200.— JULY 1865. 



LONDON: 



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Printers and Publishers to the University of London. 

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



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