Vol. 27. APRIL 1889. No. 167. 



Published the First Day of every Month. — Price 25. Qd. 



THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE, 



AND 



JOURNAL OF SCIENCE. 



Being a Continuation of Tilloch^s '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. 



^HIEF CLER'- 



FIFTH SERIES:^^— — -^ 



N° 167.— APRIL 1889. 



LONDON: 



PEINTED BY TAYLOE AND FBANCIS, BED LION COURT, FLEET STREET. 



Sold by Kent and Co.; Simpkin, Marshall, and Co. ; 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. 



