T H E 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



CONDUCTED BY 



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

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

 RICHARD PHILLIPS, F.R.S.L.&E. F.G.S. &c. 

 ROBERT KANE, M.D. M.R.F.A. 



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

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



VOL. XXV. 



NEW AND UNITED SERIES OF THE PHILOSOPHICAL MAGAZINP:, 

 ANNALS OF PHILOSOPHY, AND .TOURNAL OF SCIENCE. 



JULY— DECEMBER, 1844. 



LONDON: 



RICHAIID AND JOHN E. TAYLOR, RED LION COURT, FLEKT STREET, 



Printers and Publishers to the University of London; 



SOLD BY LONGMANS, BROWN, GREEN, AND LONGMAN ; CADELLJ 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 G. W, M. REYNOLDS, PARIS. 



