A Popular History of Astronomy During the Nineteenth Century Fourth Edition   By: Agnes M. (Agnes Mary) Clerke (1842-1907)

BY THE SAME AUTHOR

PROBLEMS IN ASTROPHYSICS. Demy 8vo., cloth. Containing over 100 Illustrations. Price 20s. net.

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[Illustration: THE GREAT NEBULA IN ORION, 1883

See p. 408 ]

A POPULAR HISTORY OF ASTRONOMY DURING THE NINETEENTH CENTURY

by

AGNES M. CLERKE

[Illustration: JUPITER 1879

SATURN 1885]

London Adam and Charles Black 1908

First Edition, Post 8vo., published 1885 Second Edition, Post 8vo., published 1887 Third Edition, Demy 8vo., published 1893 Fourth Edition, Demy 8vo., published 1902 Fourth Edition, Post 8vo., reprinted February, 1908

PREFACE TO THE FOURTH EDITION

Since the third edition of the present work issued from the press, the nineteenth century has run its course and finished its record. A new era has dawned, not by chronological prescription alone, but to the vital sense of humanity. Novel thoughts are rife; fresh impulses stir the nations; the soughing of the wind of progress strikes every ear. "The old order changeth" more and more swiftly as mental activity becomes intensified. Already many of the scientific doctrines implicitly accepted fifteen years ago begin to wear a superannuated aspect. Dalton's atoms are in process of disintegration; Kirchhoff's theorem visibly needs to be modified; Clerk Maxwell's medium no longer figures as an indispensable factotum; "absolute zero" is known to be situated on an asymptote to the curve of cold. Ideas, in short, have all at once become plastic, and none more completely so than those relating to astronomy. The physics of the heavenly bodies, indeed, finds its best opportunities in unlooked for disclosures; for it deals with transcendental conditions, and what is strange to terrestrial experience may serve admirably to expound what is normal in the skies. In celestial science especially, facts that appear subversive are often the most illuminative, and the prospect of its advance widens and brightens with each divagation enforced or permitted from the strait paths of rigid theory.

This readiness for innovation has undoubtedly its dangers and drawbacks. To the historian, above all, it presents frequent occasions of embarrassment. The writing of history is a strongly selective operation, the outcome being valuable just in so far as the choice what to reject and what to include has been judicious; and the task is no light one of discriminating between barren speculations and ideas pregnant with coming truth. To the possession of such prescience of the future as would be needed to do this effectually I can lay no claim; but diligence and sobriety of thought are ordinarily within reach, and these I shall have exercised to good purpose if I have succeeded in rendering the fourth edition of A Popular History of Astronomy during the Nineteenth Century not wholly unworthy of a place in the scientific literature of the twentieth century.

My thanks are due to Sir David Gill for the use of his photograph of the great comet of 1901, which I have added to my list of illustrations, and to the Council of the Royal Astronomical Society for the loan of glass positives needed for the reproduction of those included in the third edition.

London, July , 1902.

PREFACE TO THE FIRST EDITION