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. 

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

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



" 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. XXIX. 



NEW AND UNITED SERIES OF THE PHILOSOPHICAL MAGAZINE, 

 ANNALS OF PHILOSOPHY, AND JOURNAL OF SCIENCE. 



JULY— DECEMBER, 1846. 



LONDON: 



RICHARD AND JOHN E. TAYLOR, RED LION COURT, FLEET STREET, 

 Printers and Publishers 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. 



