

/ 



THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



CONDUCTED BY 



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

 SIR 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. 



y jUN2 51? 



WILLIAM FRANCIS, F.L.S. 



/ 



"Nee aratiearuni sane lextua ideo melior quia ex sctila gignunt, uec nostev 

 vilior quia ex alienis tibaiTins ut apes." Just. laps. Polit. lib. i. cap. 1. Not. 



VOL. XXXIII.— SIXTH SERIES. 

 JANUARY— JUNE 1917. 



m£ 



LONDON: 

 TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET. 



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

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

 AND VEUVE J. BOYVEAU. PARIS. 



