THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



CONDUCTED BY 



LORD KELVIN, LL.D. F.R.S. &o, 

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

 vihor qu.a ex alienis libamus ut apes." Just. Lips. Polit. lib. i. cap. 1 . Not. 



VOL. XLIIL— FIFTH SERIES. 

 JANUARY— JUNE 1897. 



LONDON: 

 TAYLOR AND FKANCIS, RED LION COURT, FLEET STREET. 



S0LD ™™;™~' IIAMILT0 *' KENT ' A ™ co - ">•; ™™« -n co. 



8MmiAvn,nv » ARLES BLACK '— T - A ™ *•**», EDINBURGH J 



SMITH AND SOJs, GLASGOW J-IIODGES, FIGGIS. AND CO., DUBLIN'— 



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



AND ASIIER AND CO., BERLIN. 



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