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SATURN AND ITS SYSTEM :

CONTAINING DISCUSSIONS OF

THE MOTIONS (REAL AND APPARENT) AND TELESCOPIC
APPEARANCE OF THE PLANET SATURN, ITS SATELLITES,
AND RINGS; THE NATURE OF THE RINGS; THE GREAT
INEQUALITY' OF SATURN AND JUPITER; AND THE

HABITABILITY OF SATURN.

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NOTES ON CHALDÆAN ASTRONOMY, LAPLACE'S NEBULAR THEORY,
AND THE HABITABILITY OF THE MOON; A SERIES OF TABLES WITH
EXPLANATORY NOTES; AND EXPLANATIONS OF ASTRONOMICAL TERMS.

BY

RICHARD A. PROCTOR, B.A.

Late Scholar of St. John's College, Cambridge, and King's College, London.

ILLUSTRATED BY

FOURTEEN ENGRAVINGS IN STEEL AND COPPER.

THE HEAVENS DECLARE THE GLORY OF GOD,

THE FIRMAMENT SHOWETH HIS HANDYWORK.

LONDON:
LONGMAN, GREEN, LONGMAN, ROBERTS, & GREEN.

Heav'n
Is as the book of God before us set,
Wherein to read His wondrous works, and learn
His seasons, hours, or days, or months, or years.

MILTON. .

This I say, and would wish all men to know and lay to heart, that he who discerns nothing but Mechanism in the Universe, has in the fatallest way missed the Secret of the Universe altogether.

CARLYLE.

PREFACE.

I HAVE endeavoured in this work to give a complete account of the phenomena presented by the planet Saturn and its system. It might appear, at first sight, that a single planet, however interesting or elaborate the scheme of which it is the centre, should rather be made the subject of a chapter than of a volume, even of the moderate dimensions of the present. It will be found, however, that much that is contained in these pages, is applicable, with suitable changes in matters of detail, to all the members of the solar system.

The inquiry into the nature of the rings, in Chapter V., deals with a subject not uninteresting, I think, on its own account, but which gathers an additional interest from its bearing on the speculations of Laplace. It is not altogether impossible that in the variations perceptibly proceeding in the Saturnian ring-system a key may one day be found to the law of development under which the solar system has reached its present condition.

Certain points of resemblance between the relations of Saturn and our earth, as respects the variations of their seasons, have induced me to devote somewhat more space to the consideration of the celestial phenomena presented to the Saturnians than the nature of the subject might appear to warrant. These features of resemblance--singular in

planets that differ so widely in all other respects—may be thus presented : The vernal equinoxes of the northern hemispheres of Saturn and the earth occur when the heliocentric longitudes of those planets are respectively 171° 43' 35":1, and 180°; the axes of Saturn and the earth are inclined 26° 49' 271.87 and 23° 27' 24":69, respectively, to the respective orbital planes of the two planets; and the north pole of the Saturnian celestial sphere is separated by an are of only 7° 7' 24" from the north pole of our heavens : again, the longitudes of the perihelia of the orbits of Saturn and the earth are respectively 90° 23' 36":4, and 100° 38' 1".8; and Saturn and the earth are in perihelion after passing over 98° 40' 1":3 and 100° 38' 1".8, respectively, in longitude, from the autumnal equinoxes of their respective northern hemispheres. Thus the variations in the Saturnian seasons more directly illustrate the corresponding variations in those of the earth than might, at first sight, be supposed. It will be seen from the note on page 117 that even the examination of the appearance of the rings to the Saturnians is not without its bearing on terrestrial phenomena.

The connection between the subjects treated of in the notes forming Appendix I., and the main subject of the work, will appear on perusal. The reader is reminded that these are notes, not essays; they contain merely the heads of arguments supporting opinions expressed in the body of the work.

The Tables numbered VII., VIII., X. and XI. now appear for the first time: parts of the other tables, also, are original. The sources from which the tables have been derived, or the formulæ from which they have been calculated, are given in the explanations of the Tables, which I have endeavoured

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