I 



THE 

 LONDON, EDINBURGH, a.nu DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



CONDUCTED BY 



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. 

 JOHN TYNDALL, F.R.S. &c. 



" Nee aranearum sane textus ideo melior quia ex se fila gignunt, nee noster 

 vilior quia ex alienis libamus u apes." Just. Lips. Polit. lib. i. cap. 1 . Not. 



VOL. XXIII.— FOURTH SERIES. 

 JANUARY— JUNE, 1862. 



LONDON. 



TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET, 

 Printers and Publishers to the University of London j 



SOLD BY LONGMAN, GREEN, LONGMANS, AND ROBERTS ; SIMPKIN, MARSHALL 



AND CO.; WHITTAKER AND CO.; AND PIPER AND CO., LONDON: 



BY ADAM AND CHARLES BLACK, AND THOMAS CLARK, 



EDINBURGH," SMITH AND SON, GLASGOW; HODGES 



AND SMITH, DUBLIN ; AND PUTNAM, 



NEW YORK. 



