Vol. 50. OCTOBER 1875. No. 331 



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



THE 

 LONDON, EDINBURGH, ato DUBLIN 



PHILOSOPHICAL MAGAZINE, 



AND 



JOURNAL OF SCIENCE. 



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

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



CONDUCTED BY 



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

 SIR WILLIAM THOMSON, Knt. LL.D. F.R.S. &c. 



AND 



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



: — v t% 



FOURTH SERIES. 



N° 331.— OCTOBER 1875. 



LONDON: 



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



Printers and Pv.blishers to the University of London. 



Sold by Longmans, Green, Reader and Dyer ; Kent and Co. ; Simpkin, Marshall and 

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