THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



CONDUCTED BY 



SIR ROBERT KANE, LL.D. F.R.S. M.R.I.A. F.C.S. 



AND 



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. XL.— FOURTH SERIES. 

 JULY— DECEMBER 1870. 



LONDON. 



TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET, 



Printers and Publishers to the University of London j 



SOLD BY LONGMANS, GREEN, READER, AND DYER J SIMPKIN, MARSHALL AND CO. 



WHITTAKER AND CO.; AND KENT AND CO., LONDON! — BY ADAM AND 



CHARLES BLACK, AND THOMAS CLARK, EDINBURGH J 



SMITH AND SON, GLASGOW; HODGES AND 



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NEW YORK. 



