THE 

 LONDON, EDINBURGH, axd DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



COXDfCTED BY 



SIR ROBERT KAXE ; LL.D. F.R.S. M.R.I.A. F.C.S. 

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



AND 



WILLIAM FRAXCIS, Ph.D. F.L.S. F.R.A.S. F.C.S. 



"Nee aranearum sane textus ideo melic-r quia ex se fila gignunt, nee noster 

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



VOL. XIII.— FIFTH SERIES, 

 JANUARY— JUXE 1882. 



LOS BOX: 

 TAYLOE AND FEANCIS, EED LION COUET, FLEET STEEET. 



BOLD BY LONGMANS, GREEN, READER, AND DVEE ; KENT AND CO, ; SIMPKIN, MARSHALL, 



AND CO. ; AND WHITTAKER AND CO. ; AND BY ADAM AND CHARLES BLACK, 



AND THOMAS CLARK, EDINBURGH ; SMITH AND SON, GLASGOW \ — 



DODGES, FOSTER, AND CO., DUBLIN; PUTNAM, NEW 



YOKKJ— AND ASHER AND CO., BERLIN. 



