Vol. 32. AUGUST 1891. No. 195. 



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,' 

 Nicholson's 'Journal, 9 and Thomson's 'Annals of Philosophy. 7 



CONDUCTED BY 



SIR WILLIAM THOMSON, Knt. LL.D. P.R.S. <fcc. 

 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° 195.— AUGUST 1891, 



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