LONDON, EDINBURGH, AND DUBLIN

PHILOSOPHICAL MAGAZINE

AND

JOURNAL OF
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.

"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. XLIX.-FOURTH SERIES.
JANUARY-JUNE 1875.

LONDON.

TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET,
Printers and Publishers to the University of London;

SOLD BY LONGMANS, GREEN, READER, AND DYER; 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 :-

HODGES, FOSTER, AND CO, DUBLIN:-PUTNAM, NEW
YORK:-AND ASHER AND CO., BERLIN.

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.

"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. XLIX. -FOURTH SERIES.
JANUARY-JUNE 1875.

LONDON.

TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET,
Printers and Publishers to the University of London;

SOLD BY LONGMANS, GREEN, READER, AND DYER; 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:-
HODGES, FOSTER, AND CO, DUBLIN:--PUTNAM, NEW
YORK:-AND ASHER AND CO., BERLIN.