670

THE

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.

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.

"Meditationis est perscrutari occulta; contemplationis est admirari perspicua . . . . . Admiratio generat quæstionem, quæstio investigationem, investigatio inventionem."-Hugo de S. Victore.

'Cur spirent venti, cur terra dehiscat,

Cur mare turgescat, pelago cur tantus amaror,
Cur caput obscura Phoebus ferrugine condat,
Quid toties diros cogat flagrare cometas ;
Quid pariat nubes, veniant cur fulmina cœlo,
Quo micet igne Iris, superos quis conciat orbes
Tam vario motu."

J. B. Pinelli ad Mazonium.

CONTENTS OF VOL. XLVII.

(FOURTH SERIES.)

NUMBER CCCIX.-JANUARY 1874.

Mr. J. Y. Buchanan on an Apparatus for Gas-analysis.

(With a Plate.)..

M. H. Herwig on the Disintegration of the Electrodes in the

Galvanic Arc of Light

Prof. Challis's Theory of the Source of Terrestrial Magnetism.

Mr. R. S. Brough on Wheatstone's Bridge..

Prof. Challis's further Discussion of the Analytical Principles

of Hydrodynamics, in Reply to Mr. Moon

Page

1

6

14

22

25

M. A. F. Sundell on the Electromotive and Thermoelectric

Forces of some Metallic Alloys in contact with Copper.... 28

Mr. S. Roberts on a simple Condensing Collector for Fric-

tional Electrical Machines

49

Prof. W. F. Barrett on the Molecular Changes that accom-

pany the Magnetization of Iron, Nickel, and Cobalt

Notices respecting New Books :—

51

56

Mr. J. M. Wilson's Elementary Geometry

Proceedings of the Royal Society :-

Dr. J. H. Gladstone and Mr. A. Tribe on an Air-Battery. 61

Mr. O. Reynolds on the Condensation of a Mixture of

Air and Steam upon Cold Surfaces.

Proceedings of the Geological Society :-

Mr. S. Sharp on the Oolites of Northamptonshire.-

Part II..

On some Phenomena of Illumination, by A. Lallemand

On a Process for verifying the Nodes in a Sounding Pipe, by

M. Bourbouze

67

74

77

80

NUMBER CCCX.-FEBRUARY.

Lord Rayleigh on the Manufacture and Theory of Diffraction-

gratings....

Mr. O. Heaviside on Wheatstone's Bridge

Mr. J. Croll on the Physical Cause of Ocean-currents

Prof. W. H. Miller on Quartz, Ice, and Karstenite

Prof. E. C. Pickering's Measurements of the Polarization of

the Light reflected by the Sky and by one or more Plates of

Glass

127