Vol. 32. 



NOVEMBER 1891 



No. 198. 



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 TillocKs 'Philosophical Magazine,' 

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



CONDUCTED BY 



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

 GEORGE FRANCIS FITZGERALD, M.A. F.R.S. 



AND 



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



FIFTH SERIES. 



N° 198.— NOVEMBER 1891, 



LONDON: 



PRINTED BY TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET. 



Sold by Simpkin, Marshall, Hamilton, Kent, and Co., Ld. ; and Whittaker and Co. ; — 

 and by A. and C. Black, and T. and T. Clark, Edinburgh ; Smith and Son, 

 Glasgow: — Hodges, Figgis, and Co., Dublin: — Putnam, New York : — Veuve J. 

 Boyveau, Paris : — and Asher and Co., Berlin. 



