Vol. 33, 



MAY 1867. 



No. 224. 



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, 9 

 Nicholson 9 8 'Journal/ and Thomson's ( Annals of Philosophy/ 



CONDUCTED I1Y 



SIR DAVID BREWSTER, K.H. LL.D. F.R.S. L.&E. &c. 

 SIR ROBERT KANE, M.D. F.R.S. M.R.I.A. 

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



FOURTH SERIES 



N° 224.— MAY 1867. 



LONDON: 



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



ty of London. 



Printers 



Sold by Longmans, Green 

 Co. ; Whittaker and Co 

 Thomas Clark, Edinbi 

 Dublin : — and Putnam, 



Agency of Smithsonian Institution. 



WILLIAM WESLEY, 



aSooksfller anU Publisher, 

 8i, Fleet Street, London. 



Co. ; Simpkin, Marshall and 

 -and by A. and C. Black, and 

 sgow : — Hodges and Smith, 



