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Degree of Light. And therefore the Use of that wonderous Ring (though very great, to be sure) may be to us entirely unknown.
Euphros. Well, I would not be over inquisitive; 'tis a Pleasure we know there's such a Ring, be the Use of it what it will. But, pray, how many Moons hath Saturn?
Cleon. Through our common Telescopes we discover but two or three, though with the best Sort you may see five, of which I intend to give you a farther Account at another more convenient Time.
Eupbrof. I have no Occasion to ask concerning his Conjunctions, Oppositions, Retrogradations, &c. which I fee, from the Plate, must follow from his being a fuperior Planet, or having his Orbit lying without that of the Earth, as in Jupiter and Mars you explained to me; and would only observe, that whether he be in Conjunction or Opposition, it appears to me that his apparent Magnitude can be but little varied, because of the much smaller Diameter of the Earth's Orbit.
Cleon. 'Tis well observed, Sister; for there is but little Difference if viewed in the Opposition, when he is nearest; or in the Conjunction, when he is farthest off.
Euphros. Did not the great Distance and long Period of Saturn's Revolution occafion him to be taken Notice of among the Heathens in ancient Times ?
Cleon. As to his great Distance, they were far from being Astronomers good enough to know any Thing about that : But his flow Motion, and the great Length of his Year, occafioned them to make him the Emblem of Time.
Euphrof. In what Manner?
Cleon. They represented him as a decrepid, wrinkled old Man, with a long Beard, and hoary Head ; round shoulder'd, hollow Jaw'd, Aat Nosed, hooked Chin’d, black Lips, and crooked Hands. In his Right Hand was a rusty Scythe, and in his Left he held a Serpent biting his Tail; or, as some say, a Child, which he is about to devour.
Euphrof. Why then he made but a sort of contemptible Figure among Men in Days of old, I find; he was indeed a very fit Symbol of Time, which gives to every
Thing a horrid Aspect; or cuts down, and devours it; and that in an endless Circulation of Ages.Pray, is there any Thing farther remarkable of Saturn?
Cleon. There are abundance of Things fabled of him, as you may meet with, and doubtless have, in many Books; but the moft notable Thing of all is the Time in which he lived, called the Golden Age.
Euphros. I have read a Description of that extraordinary Age in fome Poet, but forget which.-I Mould be glad to hear it repeated.
Cleon. Virgil gives a beautiful Description thereof in his Eighth Book of the Æneid; and Ovid in his First Book of Metamorphoses. Which, since it is agreeable to you, I fhall rehearse in Mr. Dryden's Language.
The Golden Age was first, when Man, yet new,
In following Years the bearded Corn ensu'd
DI A L O G U E XIII.
On the Use of the GEOCENTRIC PLANETARIUM
by Means of an Ephemeris.
System, and I am well assured, my Euphrofyne, you underitand the general Phänomena thereof very well; but something yet remains to be understood upon this Head, and I am willing to hope will give you as much Pleasure as any Part of our past Speculations, as it is of a practical Nature, and what you are to perform with your own Hands.
Eupliros. I long to know what it is, Cleonicus, as every new Idea gives me new Delight, Cleon. What I mean is, what I some Time ago
hinted to you, viz. That it is not enough for you to know the speculative Part of Astronomy, but also that you learn to find the Places and relative Aspects of the Planets, from an EPHEMERIS, for every Day of the Year.
Euphrof. And do you think I am capable of doing this, Cleonicus
Cleon. Yes, what should hinder you, when you are put into a proper Method for it?
Euphrof. But I suppose I must first learn the Use of that Book you call an Ephemeris.
Cleon. You muit. Here it is._ Look at it.
Euphrof. It is but small indeed, but it is filled with fuch a Number of Characters, Figures, and Columns, that at first View I know not what to make of it. Cleon. That is every One's Cafe in a new Attempt;
when you consider each Article of the Ephemeris feparately you will find it easy enough to understand.
Euphrof. But first tell me why this little Book is called an Ephemeris?
Cleon. Because it is a Diary, or daily Account of the Motions or Places of the Planets, as they appear to the Eye, placed both in the Sun, and at the Earth, throughout the Year.
Euphrof. But why do you suppose the Eye to view the Planets from the Sun, fince that is impoffible?
Cleon. Because on that Suppofition you can observe or assign for any Time the true Places of the Planets in the Ecliptic; and this true Place seen from the Sun, is called the Heliocentric Place of the Planets, for the Name of the Sun in Greek is Helios ; but if the Planets are viewed from the Earth (called in Greek, Ge) then their Places and Motions are called Geocentric.
Euphrof. I understand you, I believe, pretty well; I see on the Right Hand Page, for every Month, a small Table with the Title of The Heliocentric Motions; as there, on the Top, for the Month December, 1755.
The Heliocentric Motions. h ry
Vol 2010 ole DI 1129 261 4 22 24 331 9 3129 629 35 4 45 27
8 7 1 0 16951 1 29 451 5 8.29 27119 13.14 54/11 TIR 7 16|29 541 5 30 10053124 18122 48 1447 21 OO M 3 5 534 57/29 241 42 19 41 26100
401 49730 8 3615 m 38
Cleon. Very well, my Euphrosyne. You observe that Table divided in 7 Columns; in the first is placed every 5th Day of the Month beginning with the first. On the Top of each of the other Columns, the Character of the Planet and of the Sign in which it is on the first Day of the Month; and the Figures in the respective Columns thew the Place in Degrees and Minutes which the Planet is in, as seen from the Sun precisely at 12 o'Clock at Noon, on the several Days in the first Column; for
you must know, the Astronomers always begin their Day at Noon.
Euphrol. This is all so plain, that I can't but apprehend it; and thus for Instance, on December the ift, at 12 o'Clock, I observed the Heliocentric Place of Saturn (h) is in 29° : 26' of Capricorn (w); of Jupiter (4) in 4°: 22' of Libra (4); of Mars (8) 24°: 33 of Gemini (I); of the Earth (ė) 9° : 3 of Gemini (u); of Venus (%) in 29°: 6' of Sagittarius (F); and of Mercury (%) in 18° : 40' of Cancer (%); and so for any other Day there Specified.
Cleon. Very right, my Euphrosyne, I see there will be no Difficulty about the other Table of the Geocentric Motions, where the Place of the Sun and each Planet is given in their proper Columns, as viewed from the Earth, for every Day at Noon.
Euphrof. But besides these, there are several other Tables and Columns on the fame Page; pray, what is their Use?
Cleon. We shall see that hereafter, Sister; the Heliocentric and Geocentric Motion will be sufficient at this Time to consider; and because we want to know conftantly in what Part of the Ecliptic the Planets are, their Geocentric Places are shewn for every Day, as you see for the Month December *
* Tables of the Heliocentric and Geocentric Motions or Places for December 1755, are here added from Parker's Ephemeris, left the Reader should not have the said Book at Hand; and one Month only is sufficient for an Example of its Use.