﻿^ ol - 41. APRIL 1871. 



No. 273. 



Published the First Day of every Month.— Price 2s. 6rf. 



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. 



AND 



WILLIAM FRANCIS, Ph.D. F.L.S. F.R.A.S. F.C.S. 



FOURTH SERIES. 



N° 273.— APEIL 1871, 



LO NDO N: 



PRINTED BY TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET, 



Printers and Publishers to the University of London. 



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



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