THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



CONDUCTED BY 



LORD KELVIN, G.C.Y.O. D.O.L. LL.D. F.R.S. &c. 

 GEORGE FRANCIS FITZGERALD, M.A. Sc.D. F.R.S. 



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. XLIX.— FIFTH SERIES. 

 JANUARY— JUNE 1900. 



LONDON: 

 TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET. 



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



AND BY ADAM AND CHARLES BLACK; T. AND T.CLARK, EDINBURGH; 



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



PUTNAM, NEW YORK, — VEUVE J. BOYVEAU, PARIS J 



AND ASHER AND CO., BERLIN 



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