THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



CONDUCTED BY 



LORD KELVIN, LL.D. P.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 

 vilior quia ex alienis libaraus ut apes." Just. Lips. Polit. lib. i. cap. 1. Not. 



VOL. XXXIV.— FIFTH SERIES. 

 JULY— DECEMBER 1892. 



LONDON: 

 TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET. 



SOLD BY SIMPKIN, MARSHALL, HAMILTON, KENT, AND CO., LD.; WI1ITTAKER AND CO. 



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



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



PUTNAM, NEW YORKJ— VEUVE J. BOYVEAU ; PARIS; — 

 AND ASHEB AND CO., BERLIN. 



