

Vol. 31. APRIL 1891. No. 191 



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



THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE, 



AND 



JOURNAL OF SCIENCE. 



Being a Continuation of Tilloclis 'Philosophical Magazine? 

 Nicholsons 'Journal? and Thomsons 'Annals of Philosophy. ,' 



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. 



N° 191.— APRIL 1891. 



WITH ONE PLATE. 

 Illustrative of Mr. A. A. Michelson's Paper on the Application^)^ 

 Interference -Methods to Spectroscopic Measurements. 



LONDON: 



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