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.

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. XL.-FOURTH SERIES.

JULY-DECEMBER 1870.

LONDON.

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

SOLD BY LONGMANS, GREEN, READER, AND DYER; SIMPKIN, MARSHALL AND CO. ; WHITTAKER AND CO.; AND KENT AND CO., LONDON:-BY ADAM AND

CHARLES BLACK, AND THOMAS CLARK, EDINBURGH;
SMITH AND SON, GLASGOW; HODGES AND

SMITH, DUBLIN; AND PUTNAM,

NEW YORK.

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

2

CONTENTS OF VOL. XL.

(FOURTH SERIES.)

NUMBER CCLXIV.-JULY 1870.

Mr. J. Ball on the Cause of the Descent of Glaciers

Archdeacon Pratt's Reply to M. Delaunay's objection to the late

Mr. Hopkins's Method of determining the Thickness of the

Earth's Crust by the Precession and Nutation of the Earth's

Axis

Prof. E. Edlund on the Path of Electrical Induction- and Dis-

junction-Currents through Gases of various Densities, and

between Poles of different shapes

Mr. A. S. Davis on a possible Cause of the Bright Line observed

by M. Angström in the Spectrum of the Aurora Borealis

Mr. R. Moon on the Solution of Linear Partial Differential

Equations of the Second Order involving two Independent

Variables

Mr. S. E. Phillips on a Simple Method of Constructing high

Electrical Resistance

.....

Prof. von Bezold's Researches on the Electrical Discharge..

The Rev. J. M. Heath on the Interchangeability of Heat and

Mechanical Action....

Proceedings of the Royal Society :-

Mr. Warren De La Rue, Dr. Balfour Stewart, and Mr. B.

Loewy on the Positions and Areas of the Spots observed

at Kew during the years 1864-66, also the Spotted Area

of the Sun's visible disk from the commencement of 1832

up to May 1868.....

Mr. H. T. Brown on the Estimation of Ammonia in Atmo-

spheric Air....

Mr. H. E. Roscoe and Dr. T. E. Thorpe on the Relation

between the Sun's Altitude and the Chemical Intensity

of Total Daylight in a Cloudless Sky

Prof. C. Piazzi Smyth on Supra-annual Cycles of Tempe-

rature in the Earth's Surface-crust

...

Page

1

10

14

33

35

41

42

51

53

54

56

58

The Rev. S. Haughton on the Constituent Minerals of the

Granites of Scotland, as compared with those of Donegal. 59

Mr. H. E. Roscoe on Vanadium

62

Proceedings of the Geological Society :-

Prof Huxley on Hypsilophodon, a new Genus of Dinosauria 68

Prof. Huxley on the Affinity between the Dinosaurian Rep

tiles and Birds

Prof. Huxley on the Dinosauria of the Trias

69

70