Vol. 28. DECEMBER 1889. No. 175 



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



THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE, 



A1S T D 



JOURNAL OF SCIENCE. 



Being a Continuation of Tilloclis l Philosophical Magazine,' 

 Nicholson s 'Journal? and Thomson 8 '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. 



<\S* 



FIFTH SERIES. 



N° 175.— DECEMBER 1889. 



LONDON: 



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