Vol. 50. SEPTEMBER 1875. No. 330. 



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



THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE, 



AND 



JOUUNAL OF SCIENCE. 



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

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



CONDUCTED BY 



SIR ROBERT KANE, LLD. 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. 



FOURTH SERIES. 



N° 330.— SEPTEMBER 1875. 



LONDON: 



PBINTED BY TAYLOB AND FRANCIS, BED LION COUBT, FLEET 6TBEET, 



Printers and Publishers to the University of London. 



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

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