THE 

 LONDON, EDINBURGH, and 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 ut apes." Just. Lips. Polil. lib. '\. cap. 1 . Not. 



VOL. XVII.— FOURTH SERIES. 

 JANUARY— JUNE, 18.59. 



LONDON. 



TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET, 

 Printers and Publishers to the University of London ; 



SOI. I) BY LONGMAN, BROWN, GRIiEN, LONGMANS, AND ROBERTS; SIMPKIN, 

 MARSHALL ANO CO.; WIIITTAKEK AND CO.; AND VlVliU AND CO., 



LONDON : BY ADAM AND CHARLES BLACK, AND THOMAS 



CLARK, EDINBURGH; SMITH AND SON, GLASGOW ; 



HODGES AND SMITH, DUBLIN ; AND 



PUTNAM, NEW YORK. 



