THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



CONDUCTED BY 



SIR ROBERT KANE, LL.D. F.R.S. M.R.I.A. F.C.S. 

 SIR WILLIAM THOMSON, Knt. LL.D. F.R.S. &c. 



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 libamus ut apes." Just. Lips. Polit. lib. i. cap. 1. Not. 



VOL. XXVIII.— FIFTH SERIES. 

 JULY— DECEMBER 1889. 



LONDON: 

 TAYLOE AND FKANCIS, EED LION COURT, FLEET STREET. 



SOLD BY KENT AND CO. ; SIMPKIN, MARSHALL, AND CO. J AND WniTTAKER AND CO. ; 

 AND BY ADAM AND CHARLES BLACK, AND 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. 



