THE
LONDON, EDINBURGH, AND DUBLIN
PHILOSOPHICAL MAGAZINE
AND
JOURNAL OF SCIENCE.
CONDUCTED BY
SIR DAVID BREWSTER, K.H. LL.D. F.R.S.L. & E. &c.
SIR ROBERT KANE, M.D., F.R.S., M.R.I.A.
WILLIAM FRANCIS, Ph.D. F.L.S. F.R.A.S. F.C.S.
JOHN TYNDALL, F.R.S. &c.
"Nee aranearum sane textus ideo melior quia ex se fila gignunt, nee noster vilior quia ex alienis libamus ut apes." Just. Lips. Polit. lib. i. cap. 1. Not.
VOL. XXL.—FOURTH SERIES.
JANUARY–JUNE, 1861.
LONDON.
TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET,
Printers and Publishers to the University of London;
SOLD BY LONGMAN, GREEN, LONGMANS, AND ROBERTS; SIMPKIN, MARSHALL
AND CO.; WHITTAKER AND CO.; AND PIPER AND CO., LONDON:—
BY ADAM AND CHARLES BLACK, AND THOMAS CLARK,
EDINBURGH; SMITH AND SON, GLASGOW; HODGES
AND SMITH, DUBLIN; AND PUTNAM,
NEW YORK.
