Vol. 28. OCTOBER 1889. No. 173. 



W 



Published the First Day of every Month 



THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE, 



AND 



JOURNAL OF SCIENCE. 



Being a Continuation of Tilloctis 'Philosophical Magazine/ 

 Nicholson s 'Journal/ and Thomson's '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. 



FIFTH SERIES. 



N° 17 3.~ OCTOBER 1889. 



WITH THEEE PLATES. 



Illustrative of Prof. E. Wiedemann's Paper on the Mechanics of Lumi- 

 nosity; Mr. J. C. M c Connel's on Diffraction-Colours, with special 

 reference to Coronae and Iridescent Clouds ; and Mr. E. P. D'Arcy's 

 on the Viscosity of Solutions. 



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