THE 



¥& 



LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



CONDUCTED BY 



SIR OLIVER JOSEPH LODGE, D.Sc, LL.D, F.R.S. 

 .IR JOSEPH JOHN THOMSON, O.M., M.A., Sc.D., LL.D., F.R.S. 

 JOHN JOLY, M.A., D.Sc, F.R.S, F.G.S. 

 GEORGE CAREY FOSTER, B.A, LL.D, F.R.S. 



AND 



WILLIAM FRANCIS, F.L.S. 



7 



"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.— SIXTH SERIES. 

 JULY— DECEMBER 1917. 



| g/ ?? 



LONDON-. 

 TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET 



SOLD BY 8IMPKIN, MARSHALL, HAMILTON, KENT, AND CO., LD. 



SMITH AND *ON, GLASGOW; — HODGES, FIGGIS, AND CO., DUBLIN, — 



AND VEUVE J. BOYVEAU, PARIS. 



