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THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



CONDUCTED BY 



LORD KELVIN, G.C.V.O. D.C.L. LL.D. F.R.S. Ac. 

 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 nostey 

 rilior quia ex alienis libamns ut apes." Just. Lips. Polit. lib. i. cap. 1. Not. 



VOL.; "XIIL-^IXTH SERIES. 

 JANUARY—JUKE 1907. 



LONDON: 

 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 ; AND ASHER AND CO., BERLIN. 



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