STELLAR EVOLUTION

BY THE SAME AUTHOR.

Climate and Time in their Geological Relations: A Theory of Secular Changes of the Earth’s Climate. By James Croll, of H. M. Geological Survey of Scotland. With Maps and Illustrations. 12mo. Cloth, $2.50.

Discussions on Climate and Cosmology. By James Croll, LL.D., F.R.S. With Chart. 12mo. Cloth, $2.00.

STELLAR EVOLUTION

AND ITS RELATIONS TO

GEOLOGICAL TIME

BY

JAMES CROLL, LL.D., F.R.S.

AUTHOR OF ‘CLIMATE AND TIME,’ ‘CLIMATE AND COSMOLOGY,’ ETC.

NEW YORK

D. APPLETON AND COMPANY

1889

Authorized Edition.

PREFACE.

There are two, and only two, conceivable sources from which the prodigious amount of energy possessed by our sun and solar system can possibly have been derived. Not only are these two sources radically distinct in their essential nature, but both are admitted to be real and not merely hypothetical sources of energy. The one source is gravitation; the other, the source discussed in the present volume, a source to which attention was directed some twenty years ago. A most important distinction between these two sources is this: the amount of energy available from the former can be accurately determined, but such is not the case in regard to the latter. We can tell with tolerable certainty the greatest amount of energy which gravitation could possibly have conferred on the sun and solar system; but we have, at present, no means of assigning a limit to the possible amount which might have been derived from the other source. It may have been equal to that which gravitation could afford, or it may have been twofold, fourfold, or even tenfold that amount.

We have evidently in this case a means of determining which of the two sources will ultimately have to be adopted as the source to which the energy of our solar system must be referred. For if it can be proved from the admitted facts of geology, biology, and other sciences, that the amount of energy in the form of heat which has been radiated into space by the sun during geological time is far greater than the amount which could possibly have been derived from gravitation, this will undoubtedly show that gravitation cannot account for the energy originally possessed by our system.

The First Part of the volume is devoted to the consideration of what I believe to be the probable origin of meteorites, comets, and nebulæ, and of the real source from which our sun derived his energy. The facts which support the theory here advocated, together with the light which that theory appears to cast upon those facts, are next considered; and it will be found, I think, that the theory has been very much strengthened by the recent important spectroscopic researches of Mr. Lockyer and others in reference to the constitution of nebulæ. The Second Part of the work deals with the evidence in support of the theory derived from the testimony of geology and biology as to the age of the sun’s heat. The Third, and last, Part has been devoted to questions relating to the pre-nebular condition of the universe, and the bearing which these have on theories of stellar evolution. Several subjects introduced in this part are only very briefly treated. These will, however, be considered at greater length in a future volume, “Determinism, not Force, the Foundation-stone of Evolution,” a work of a more general and abstract character, which was commenced many years ago.

Perth: January 2, 1889.

CONTENTS.

PART I.

THE IMPACT THEORY OF STELLAR EVOLUTION.

PAGE

Consideration of the Facts which support the Theory, and of the Light which the Theory appears to cast upon the Facts 12

I. Probable Origin of Meteorites 12

II. Motion of the Stars; how of such different velocities, and always in straight lines 14

III. Motion of the Stars not due to their mutual attractions 14

IV. Probable Origin of Comets 17

V. Nebulæ 18

1. Origin of Nebulæ 18

2. How Nebulæ occupy so much space 18

3. Why Nebulæ are of such various shapes 19

4. Broken fragments in a Gaseous mass of an excessively high temperature the First stage of a Nebula 19

5. The Gaseous condition the Second stage of a Nebula 24

6. The Gaseous condition Essential to the Nebular Hypothesis 25

7. The mass must have possessed an excessive temperature 26

8. Gravitation could, under no possible condition, have generated the Amount of Heat required by the Nebular Hypothesis 27

9. Condensation the Third and last stage of a Nebula 30

10. How Nebulæ emit such feeble Light 30

VI. Binary Systems 32

VII. Sudden Outbursts of Stars 33

VIII. Star Clusters 34

IX. Age of the Sun’s Heat: a Crucial Test 34

PART II.

EVIDENCE IN SUPPORT OF THE THEORY

FROM THE AGE OF THE SUN’S HEAT.

Testimony of Geology and Biology as to the Age of the Sun’s Heat 37

Testimony of Geology: Method employed 39

The Average Rate of Denudation in the Past probably not much greater than at the Present 44

How the Method has been applied 47

Method as applied by Professor Haughton 50

Method as applied by Mr. Alfred R. Wallace 51

Method as applied directly 52

Evidence from “faults” 53

Time required to effect the foregoing amount of Denudation 62

Age of the Earth as determined by the Date of the Glacial Epoch 64

Testimony of Biology 65

PART III.

EVIDENCE IN SUPPORT OF THE THEORY

FROM THE PRE-NEBULAR CONDITION OF

THE UNIVERSE.

Professor A. Winchell on the pre-nebular condition of matter 71

Mr. Charles Morris on the pre-nebular condition of matter 75

Sir William R. Grove on the pre-nebular condition of matter 78

Evolution of the Chemical Elements, and its Relations to Stellar Evolution 80

Sir Benjamin Brodie on the pre-nebular condition of matter 84

Dr. T. Sterry Hunt on the pre-nebular condition of matter 85

Professor Oliver Lodge on the pre-nebular condition of matter 87

Mr. William Crookes on the pre-nebular condition of matter 90

Professor F. W. Clarke on the pre-nebular condition of matter 98

Dr. G. Johnstone Stoney on the pre-nebular condition of matter 99

The Impact Theory in relation to the foregoing Theories of the Pre-nebular Condition of Matter 102

The Theories do not account for the Motion of the Stars 105

The Theories do not account for the Amount of Heat required 106

Evolution of Matter 107

Objection considered 109

Can we on Scientific grounds trace back the Evolution of the Universe to an Absolute First condition? 110

STELLAR EVOLUTION.