THE 



LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



CONDUCTED BY 



JOHN JOLY, M.A. D.Sc. F.R.S. F.G.S. 



AND 



WILLIAM FRANCIS, F.L.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. XVII.— SIXTH SERIES 

 JANUARY— JUNE 1909. 



' L*OR"DON] 

 TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET. 



SOLD BY SIMPKIN, MARSHALL, HAMILTON, KENT, AND CO., LD. 



SMITH AND SON, GLASGOW ;— HODGES, FIGGIS. AND CO., DUBLIN.) 



VEUVE J. BOYVEAU, PARIS J — AND ASHER AND CO., BERLIN. 





