d1. 42. NOVEMBER 1871. No. 281, 



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



THE 

 LONDON, EDINBUEGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE, 



AND 



PfV JOURNAL OF SCIENCE.' 



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

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



CONDUCTED BY 



SIR ROBERT KANE, LL.D. F.R.S. M.R.I.A. F.CT.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° 281.— NOVEMBER 1871. 



LONDON: 



PRINTED BY TAYLOR AND FRANCIS, RED LION COURT, FLEET 8TREET, 



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