V^oi: 39. FEBRUARY 1870. No. 259. 



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THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE, 



AND 



JOURNAL OF SCIENCE. 



Being a Continuation of Tilloch's * Philosophical Magazine,* 

 Nicholson's c Journal, ' and Thomson's ( Annals of Philosophy. 9 



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

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AND 



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



FOUIITH SERIES. 



N° 259.— FEBRUARY 1870. 



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