Chapter I: Front Matter

Transcriber’s Notes:

Underscores “_” before and after a word or phrase indicate _italics_ in the original text. A single underscore after a symbol indicates a subscript. Carat symbol “^” designates a superscript. Small capitals have been converted to SOLID capitals. Illustrations have been moved so they do not break up paragraphs. Typographical errors have been silently corrected. The numerical references to the NOTES, e. g. [1] have been changed to “(see NOTE x)” in order to avoid confusion with the true footnotes.

THE EVOLUTION OF WORLDS

THE MACMILLAN COMPANY
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MACMILLAN & CO., LIMITED
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THE MACMILLAN CO. OF CANADA, LTD.
TORONTO

THE EVOLUTION OF WORLDS

BY
PERCIVAL LOWELL, A.B., LL.D.

AUTHOR OF “MARS AND ITS CANALS,” “MARS AS THE
ABODE OF LIFE,” ETC.

DIRECTOR OF THE OBSERVATORY AT FLAGSTAFF, ARIZONA; NON-RESIDENT
PROFESSOR OF ASTRONOMY AT THE MASSACHUSETTS INSTITUTE OF
TECHNOLOGY; FELLOW OF THE AMERICAN ACADEMY OF ARTS AND SCIENCES;
MEMBRE DE LA SOCIÉTÉ ASTRONOMIQUE DE FRANCE; MEMBER OF THE
ASTRONOMICAL AND ASTROPHYSICAL SOCIETY OF AMERICA; MITGLIED
DER ASTRONOMISCHE GESELLSCHAFT; MEMBRE DE LA SOCIÉTÉ
BELGE D’ASTRONOMIE; HONORARY MEMBER OF THE SOCIEDAD
ASTRONOMICA DE MEXICO; JANSSEN MEDALLIST OF THE
SOCIÉTÉ ASTRONOMIQUE DE FRANCE, 1904, FOR
RESEARCHES ON MARS; MEDALLIST OF THE
SOCIEDAD ASTRONOMICA DE MEXICO FOR
STUDIES ON MARS, 1908

_ILLUSTRATED_

New York
THE MACMILLAN COMPANY
1909

_All rights reserved_

COPYRIGHT, 1909,
BY THE MACMILLAN COMPANY.

Set up and electrotyped. Published December, 1909.

Norwood Press
J. S. Cushing Co.—Berwick & Smith Co.
Norwood, Mass., U.S.A.

TO
THE PRESIDENT OF THE
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
TO MY COLLEAGUES THERE
AND TO ITS STUDENT BODY
TO WHOSE INTEREST AND ATTENTION THESE
LECTURES ARE INDEBTED
THEY ARE APPRECIATIVELY INSCRIBED

“Si je n’étais pas devenu général en chef et l’instrument du sort
d’un grand people, j’aurais couru les bureaux et les salons pour me
mettre dans la dépendance de qui que ce fût, en qualité de ministre
ou d’ambassadeur? Non, non! je me serais jeté dans l’étude des
sciences exactes. J’aurais fait mon chemin dans la route des
Galilée, des Newton. Et puisque j’ai réussi constamment dans mes
grandes entreprises, eh bien, je me serais hautement distingué aussi
par des travaux scientifiques. J’aurais laissé le souvenir de belles
découvertes. Aucune autre gloire n’aurait pu tenter mon ambition.”

—NAPOLEON Iᴱᴿ, QUOTED BY ARAGO.

The substance of the following pages was written and presented in a university course of lectures before the Massachusetts Institute of Technology—in February and March of this year. The kind interest with which the lectures were received, not only by the students and professional bodies, but by the public, was followed by an immediate request from The Macmillan Company to issue them in book form, and as such they now appear.

PERCIVAL LOWELL.
BOSTON, MASS., May 29, 1909.

CONTENTS

CHAPTER PAGE
I. BIRTH OF A SOLAR SYSTEM 1
II. EVIDENCE OF THE INITIAL CATASTROPHE IN OUR OWN CASE 31
III. THE INNER PLANETS 58
IV. THE OUTER PLANETS 94
V. FORMATION OF PLANETS 127
VI. A PLANET’S HISTORY—SELF-SUSTAINED STAGE 155
VII. A PLANET’S HISTORY—SUN-SUSTAINED STAGE 182
VIII. DEATH OF A WORLD 213

NOTES
1. METEOR ORBITS 241
2. DENSITIES OF THE PLANETS 243
3. VARIATION IN SPECTROSCOPIC SHIFT 243
4. ON THE PLANETS’ ORBITAL TILTS 244
5. PLANETS AND THEIR SATELLITE SYSTEMS 245
6. ON THE INDUCED CIRCULARITY OF ORBITS THROUGH COLLISION 250
7. CAPTURE OF SATELLITES 251

INDEX 253

LIST OF ILLUSTRATIONS

PLATES

I. Saturn _Frontispiece_
OPPOSITE PAGE
II. The Moving Nebula surrounding Nova Persei, 1901-1902 14
III. Representative Stellar Spectra 24
IV. Spectra of the Major Planets 52
V. Venus, 1896-1897 82
VI. Asteroids: Major Axes of Orbits 98
VII. Saturn—A Drawing showing Agglomerations 108
VIII. Spectrogram of Jupiter, Moon Comparison 152
IX. Spectrogram showing Water-vapor in Atmosphere of Mars 160
X. Tree Fern 176
XI. Ten Views of Mercury, showing Effect of Libration 222
XII. Spectrogram of Saturn 232

CUTS APPEARING IN TEXT
PAGE
Algol and its Dark Companion 4
Nova Persei 11
Spectrum of Nova Persei 12
The Moving Nebula surrounding Nova Persei, 1901 13
Great Nebula in Orion 17
Great Nebula in Andromeda 18
Nebula M. 100 Comæ 19
Nebula ♅ I. 226 Ursæ Majoris 20
Nebula ♅ V. 24 Comæ. Showing Globular Structure 21
Nebula M. 101 Ursæ Majoris 23
The Radiant of a Meteoric Shower 37
Diagram explaining Proportionate Visibility of Meteors 38
The Mart Iron 41
Section of Meteorite showing Widmannstättian Lines 42
Meteorite, Toluca 43
Nebula ♅ V. 14 Cygni 45
Nebula N.G.C. 1499 Persei 46
Nebula N.G.C. 6960 in Cygnus 47
Nebula M. 51 Canum Venaticorum 48
Orbits of the Inner Planets 59
Sulla Rotazione di Mercurio.—Di G. V. Schiaparelli 64
Map of Mercury. Lowell 69
Venus. October, 1896-March, 1897 78
Venus. April 12, 1909. 79
Diagram: Convection Currents in Atmosphere of Venus 81
Diagram: Shift in Central Barometric Depression 81
Spectrogram of Venus, showing its Long Day 87
Spectrogram of Jupiter, giving the Length of its Day by the
Tilt of its Spectral Lines 89
Orbits of the Outer Planets 95
Drawing of Jupiter showing its Ellipticity 103
Two Drawings of Jupiter and its Wisps 105
Photograph of Jupiter, 1909 107
Diagram of Saturn’s Rings 113
The Tores of Saturn 114
Chart showing increasing Tilts of the Major Planets 131
Orbital Tilts and Eccentricities of Satellites 133
Masses of Planets and Satellites 136
Two Drawings of Jupiter and its “Great Red Spot” 164
Sun Spots 165
Photograph of a Sun Spot 166
The Volcano Colima, Mexico, March 24, 1903 169
Jukes Butte, a Denuded Laccolith, as seen from the Northwest 170
Ideal Section of a Laccolith 170
Earth as seen from above.—Photographed at an Altitude of
5500 Feet 183
Tracks of Sauropus Primævus 188
Adventures of a Heat Ray 193
Polar Caps of Mars at their Maxima and Minima 198
Glacial Map of Eurasia 200
Map showing the Glaciated Area of North America 201
Photograph of the Moon 205
Petrified Bridge, Third Petrified Forest, near Adamana,
Arizona 210
Three Views of Venus, showing Agreement at Different
Distances 220
Diagram of Libration in Longitude due to Rotation 222
Moon,—Full and Half 225
Diagram illustrating Molecular Motion in a Gas 227
Distribution of Molecular Velocities in a Gas 229

THE EVOLUTION OF WORLDS