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Agency of Smithsonian Institution. 



WILLIAM WESLEY, 

 33oofcsellcr anti ^ubltsber, 

 8i, Fleet Street, London. 



5RUARY 1869. 



No. 247. 



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



THE 



LONDOiN, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE, 



AND 



JOURNAL OF SCIENCE. 



Being a Continuation of TillocVs 'Philosophical Magazine,* 

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



CONDUCTED RV 



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° 247.— FEBRUARY 1869. 



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