OF

ASTRONOMY:

BY

SIR JOHN F. W. HERSCHEL, BART. K.H.

M.A. D.C.L. F.R.S.L. & E. HON. M.R.I.A. F.R.A.S. F.G.S. M.C.U.P.S.

Correspondent or Honorary Member of the Imperial, Royal, and National, Academies of Sciences
of Berlin, Brussels, Copenhagen, Göttingen, Haarlem, Massachusetts (U. S.), Modena,
Naples, Paris, Petersburg, Stockholm, Turin, Vienna, and Washington (U. S);
the Italian and Helvetic Societies;

the Academies, Institutes, &c., of Albany (U. S.), Bologna, Catania, Dijon, Li usanne,
Nantes, Padua, Palermo, Rome, Venice, Utrecht, and Wilna;

the Philomathic Society of Paris; Asiatic Society of Bengal; South African Lit. and Phil. Society;
Literary and Historical Society of Quebec; Historical Society of New York;
Royal Medico-Chirurgical Soc., and Inst. of Civil Engineers, London;
Geographical Soc. of Berlin; Astronomical and
Meteorological Soc. of British Guiana;
&c. &c. &c.

A NEW EDITION.

WITH NUMEROUS PLATES AND WOOD-CUTS.

PHILADELPHIA:

BLANCHARD & LEA.

COLLINS, PRINTER.

NOTE

ΤΟ

THE FOURTH EDITION.

SEVERAL alterations and additions are made in this Edition, besides what have been introduced into the Third, to bring it up to the actual state of astronomical discovery. The elements of four new planets (Parthenope, Egeria, Victoria, and Irene) have been added, and improved elements of Iris, Metis, Hebe, and Hygeia, substituted for the provisional elements before given. The remarkable discovery of an additional ring of Saturn, and the curious researches of M. Peters on the proper motion of Sirius, with several minor features, are noticed. Where such additions are introduced in the text, they are indicated by being enclosed in brackets [ ].

London. Aug 5 181.

J. F. W. HERSCHEL.

(F)

PREFACE.

THE work here offered to the Public is based upon and may be considered as an extension, and, it is hoped, an improvement of a treatise on the same subject, forming Part 43, of the Cabinet Cyclopædia, published in the year 1833. Its object and general character are sufficiently stated in the introductory chapter of that volume, here reprinted with little alteration; but an opportunity having been afforded me by the Proprietors, preparatory to its re-appearance in a form of more pretension, I have gladly availed myself of it, not only to correct some errors which, to my regret, subsisted in the former volume, but to remodel it altogether (though in complete accordance with its original design as a work of explanation); to introduce much new matter in the earlier portions of it; to re-write, upon a far more matured and comprehensive plan, the part relating to the lunar and planetary perturbations, and to bring the subjects of sidereal and nebular astronomy to the level of the present state of our knowledge in those departments.

The chief novelty in the volume, as it now stands, will be found in the manner in which the subject of Perturbations is treated. It is not it cannot be made elementary, in the sense in which that word is understood in these days of light reading. The chapters devoted to it must, therefore, be considered as addressed to a class of readers in possession of somewhat more mathematical knowledge than those who will find the rest of the work readily