Vol. 50. JULY 1875. No. 328. 



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



THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE, 



AND 



Journal of science. 



Being a Continuation of Tilloch's e Philosophical Magazine/ 

 Nicholson's 'Journal,' and Thomson's '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. 



FOURTH SERIES. <* 



*v 



N° 328.— JULY 1875. 



LONDON: 



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