E-text prepared by Eric Hutton and the Project Gutenberg Online Distributed Proofreading Team (https://www.pgdp.net) Note: Project Gutenberg also has an HTML version of this file which includes the original illustrations. See 28247-h.htm or 28247-h.zip: (https://www.gutenberg.org/dirs/2/8/2/4/28247/28247-h/28247-h.htm) or (https://www.gutenberg.org/dirs/2/8/2/4/28247/28247-h.zip) A POPULAR HISTORY OF ASTRONOMY DURING THE NINETEENTH CENTURY * * * * * BY THE SAME AUTHOR PROBLEMS IN ASTROPHYSICS. Demy 8vo., cloth. Containing over 100 Illustrations. Price 20s. net. THE SYSTEM OF THE STARS. Second Edition. Thoroughly revised and largely rewritten. Containing numerous and new Illustrations. Demy 8vo., cloth. Price 20s. net. MODERN COSMOGONIES. Crown 8vo., cloth. Price 3s. 6d. net. A. AND C. BLACK, SOHO SQUARE, LONDON, W. * * * * * [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.