CONTENTS

Chapter Page
I.—Introduction[1]
II.—The Problem Stated[21]
III.—The Fire-mist[39]
IV.—Nebulæ—Apparent and Real[52]
V.—The Heat of the Sun[75]
VI.—How the Sun’s Heat is Maintained[95]
VII.—The History of the Sun[112]
VIII.—The Earth’s Beginning[122]
IX.—Earthquakes and Volcanoes[158]
X.—Spiral and Planetary Nebulæ[191]
XI.—The Unerring Guide[207]
XII.—The Evolution of the Solar System[246]
XIII.—The Unity of Material in the Heavens and the Earth[261]
XIV.—The First Concord[294]
XV.—The Second Concord[308]
XVI.—The Third Concord[324]
XVII.—Objections to the Nebular Theory[337]
XVIII.—The Beginning of the Nebula[348]
XIX.—Concluding Chapter[361]
Appendices[369]
Index[382]

LIST OF ILLUSTRATIONS

Fig. Page
An English Sunset tinged by Krakatoa (colour)[Frontispiece]
1.Immanuel Kant (from an old print)[7]
2.A Faint Diffused Nebulosity[17]
3.The Crab Nebula[19]
4.Jupiter[25]
5.Nebulous Region and Star-cluster[33]
6.The Great Nebula in Orion[41]
7.The Dumb-bell Nebula[45]
8.The Crossley Reflector[49]
9.The Cluster in Hercules[53]
10.Spectra of the Sun and Capella[62]
11.Spectrum of Nebula in Orion and Spectrum of White Star[64]
12.Solar Spectra with Bright Lines and Dark Lines during Eclipse[69]
13.The Nebulæ in the Pleiades[71]
14.The Sun[81]
15.I. Spectrum of the Sun. II. Spectrum of Arcturus[85]
16.Brooks’ Comet and Meteor Trail[89]
17.Argus and the surrounding Stars and Nebulosity[103]
18.Trifid Nebula in Sagittarius[105]
19.To illustrate the History of the Sun[113]
20.Solar Corona[117]
21.The Great Comet of 1882[119]
22.Special Thermometer for use in Deep Borings[129]
23.At the Bottom of the Great Bore[140]
24.Three consecutive Shells of the Earth’s Crust[145]
25.Earthquake Routes from Japan to the Isle of Wight[171]
Showing Localities of Earthquakes (colour)[175]
26.Showing Coasts invaded by the Great Sea-waves from Krakatoa[179]
The Early Stage of the Eruption of Krakatoa (colour)[180]
27.Spread of the Air-wave from Krakatoa to the Antipodes[183]
28.The great Spiral Nebula[193]
29.How to find the great Spiral Nebula[196]
30.A group of Nebulæ[199]
31.A Ray Nebula[201]
32.Portion of the Milky Way[205]
33.A Spiral Nebula seen Edgewise[211]
34.A foreshortened Spiral[212]
35.Edge-view of a Spiral boldly shown[213]
36.To illustrate Moment of Momentum[223]
37.Saturn[233]
38.The Ring Nebula in Lyra[249]
39.Lunar Craters: Hyginus and Albategnius[255]
40.A remarkable Spiral[257]
41.A clearly-cut Spiral[259]
42.The H and K Lines in the Photographic Solar Spectrum[276]
43.Spectrum of Comet showing Carbon Lines[290]
The Solar Spectrum (colour)[290]
44.Spectrum of the Sun during Eclipse[291]
45.A Spiral presented Edgewise[296]
46.The Plane of a Planet’s Orbit[298]
47.A Right Angle divided into Ten Parts[301]
48.Illustration of the Second Concord[309]
49.Orbits of the Earth, Eros and Mars[313]
50.I. A Natural System. II. An Unnatural System[318]
51.An elongated irregular Nebula[329]
52.Two-branched Spiral[345]
53.Cluster with Stars of the 17th Magnitude[353]
54.Spectrum of Nova Persei (1901)[359]
55.The Apteryx: a Wingless Bird of New Zealand[365]
56.Skeleton of the Apteryx, showing Rudimentary Wings[366]
57.Spirals in other Departments of Nature: Foraminifer[367]
58.Ditto ditto Nautilus[367]
59.To illustrate a Theorem in the Attraction of Gravitation[369]
60.First Law of Motion exemplifies Constant Moment of Momentum[375]
61.A useful Geometrical Proposition[376]
62.Acceleration of Moment of Momentum equals Moment of Force[376]
63.Moment of Momentum unaltered by Collision[380]

THE EARTH’S BEGINNING.

CHAPTER I.
INTRODUCTION.

The Earth’s Beginning—The Nebular Theory—Many Applications of the Theory—The Founders of the Doctrine—Kant, Laplace, William Herschel: Their Different Methods of Work—The Vastness of the Problem—Voltaire’s Fable—The Oak-Tree—The Method of Studying the Subject—Inadequacy of our Time Conceptions.

I TRY in these lectures to give some account of an exceptionally great subject—a subject, I ought rather to say, of sublime magnificence. It may, I believe, be affirmed without exaggeration that the theme which is to occupy our attention represents the most daring height to which the human intellect has ever ventured to soar in its efforts to understand the great operations of Nature. The earth’s beginning relates to phenomena of such magnitude and importance that the temporary concerns which usually engage our thoughts must be forgotten in its presence. Our personal affairs, the affairs of the nation, and of the empire—indeed, of all nations and of all empires—nay, even all human affairs, past, present, and to come, shrink into utter insignificance when we are to consider the majestic subject of the evolution of that solar system of which our earth forms a part. We shall obtain a glimpse of what that evolution has been in the mighty chapter of the book of Nature on which we are now to enter.