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. 

 RICHARD TAYLOR, F.L.S. G.S. Astr.S. Nat.H.Mosc.&c. 

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

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



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

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



VOL. II.— FOURTH SERIES. 

 JULY— DECEMBER, 1851. 



LONDON. 



RICHARD TAYLOR, RED LION COURT, FLEET STREET, 



Printer and Publisher to the University of London; 



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



AND CO.; s. highley; whittaker and co.; and sherwood, 



GILBERT, AND PIPER, LONDON : BY ADAM AND CHARLES 



BLACK, AND THOMAS CLARK, EDINBURGH; SMITH AND SON, 



GLASGOW ; HODGES AND SMITH, DUBLIN ; AND 



WILEY AND PUTNAM, NEW YORK. 



