THE 

 LONDON AND EDINBURGH 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



CONDUCTED BV 



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 



• AND 



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



" Nee aranearum sane textus ideo melior quia ex se fi]a gignunt, nee noster 

 vilior quia ex alienis Hbamus ut apes." Just. Lips. Monit. Polit. lib. i. cap. 1. 



VOL. XV. 



NEW AND UNITED SERIES OF THE PHILOSOPHICAL MAGAZINE, 

 ANNALS OF PHILOSOPHY, AND JOURNAL OF SCIENCE. 



JULY— DECEMBER, 1839. 



LONDON: 



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



Printers and Publishers to the University of London; 



SOLD BY LONGMAN, ORME, BROWN, GREEN, AND LONGMANS J CADELLJ 

 SIMPKIN AND MARSHALL; S. HIGHLEY ; WHITTAKER AND CO.; AND 



SHERWOOD, GILBERT, AND PIPER, LONDON : BY ADAM AND 



CHARLES BLACK, AND IHOMAS CLARK, EDINBURGH; SMITH 



AND SON, GLASGOW ; HODGES AND SMITH, DUBLIN : 



AND G. W. M. REYNOLDS, PARIS. 



