THE

LONDON, EDINBURGH, AND DUBLIN

PHILOSOPHICAL MAGAZINE

AND

JOURNAL OF SCIENCE.

CONDUCTED BY

LORD KELVIN, LL.D. P.R.S. &c.

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.

"Nec aranearum sane textus ideo melior quia ex se fila gignunt, nec noster
vilior quia ex alienis libamus ut apes." JUST. LIPS. Polit. lib. i. cap. 1. Not.

VOL. XXXIX.-FIFTH SERIES.
JANUARY-JUNE 1895.

LONDON:

TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET.

SOLD BY SIMPKIN, MARSHALL, HAMILTON, KENT, AND CO., LD.; WHITTAKER AND CO.;
AND BY ADAM AND CHARLES BLACK;-T. AND T. CLARK, EDINBURGH;

SMITH AND SON, GLASGOW;--HODGES, FIGGIS, AND CO., DUBLIN ;—
PUTNAM, NEW YORK;--VEUVE J. BOYVEAU, PARIS;—

AND ASHER AND CO., BERLIN.