Vol.11. MARCH 1881. No. 67. 



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



THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE. 



AND 



JOURNAL OF SCIENCE. 



' Being a Continuation of Tilloclis 'Philosophical Magazine? 

 Nicholsons c Journal ,' and Thomson's 'Annals of Philosophy,'' 



CONDUCTED BY 



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

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



AND 



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



FIFTH SERIES. 



N° 67.— -MARCH 1881. 



LONDON: 



PEINTED BY TAYLOR AND FBANCIS, BED LION COUBT, FLEET 8TBEET, 



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