Vol. 45. APRIL 1873. No. 300. 



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 Tilloch's 'Philosophical Magazine/ 

 Nicholson's 'Journal/ and Thomson's 'Annals of Philosophy.' 



CONDUCTED BY 



SIR ROBERT KANE, LLD. 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 SERIESo 



INT* 300.— APEIL 1873. 



LONDON: 



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



Printers and Publishers to the University of London. 



Sold by Longmans, Green, Reader and Dyer j 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. 



