Vol. 46. OCTOBER 1873. No. 306. 



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 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. 



FOURTH SERIES. 



N° 306.— OCTOBER 1873. 



LONDON: 



PEINTED BY TAYLOB AND FBANCIS, BED LION COUBT, FLEET STBEET, 



Printers and Publishers to the University of London. 



gold by Longmans, Green, Eeader and Dyer ; Kent and Co. ; Simpkin, Marshall and 

 Co. ; and Whittaker and Co. ; — and by A. and C. Black, and Thomas Clark, Edin- 

 burgh ; Smith and Son, Glasgow : — Hodges, Foster, and Co., Dublin : — Putnam, 

 New York : — and Asher and Co., Berlin. 



