When God appoints, the horned Moon renews
Her waning Light, and her whole Vifage fhews.
Fulfils her Courfe in Circles yet unknown,
And chears Mankind with Luftre not her own.

Euphrof. Chears Mankind indeed!

Universe. But, pray,

has not the Moon a very great Influence on the Earth, and Plants, and Animals thereon?

Cleon. It would be endless to recount all the fenfelefs Whimfies that have poffeffed the Noddles of the credulous Vulgar, in this Respect. Hudibras is very witty on this

Subject, and very defervedly.

The Queen of Night, whofe vaft Command
Rules all the Sea and half the Land,
And over moift and crazy Brains,

In high fpring Tides, at Mid-night reigns.

Tho' we are not to imagine that because fome have afcribed too much Dominion to the Moon, fhe has none at all; by her Nearness to the Earth, the very much affects the Air by the Power of Gravity, and caufes fuch Alterations therein as have, doubtlefs, confiderable Effects thereon, with Refpect to the Weather at fundry Times. Alfo, fhe must be a'lowed to have fome Influence on the Syftem of Humours and Juices in the Bodies of Plants and Animals, fince we find the Ebbing and Flowing of the Sea are certainly the Effects of her Attraction (as we shall more particularly confider hereafter.)

Her deftin'd Rule, o'er Ocean fhe prefides,
And pours upon the Shore her lagging Tides.

Univerfe.

Euphrof. Well, be that as it will, I am not much concerned.- 'Tis fufficiently late, but the Moon, like a Mid-night Sun, invites us with her ferene and pleasant Luftre, yet to refift the Laws of tyrant Nature, and banifhes Sleep from my Eyes; the Bed is a gloomy Idea.

I could, methinks, fpend the whole Night in walking over the pleafing fhady Scenes of the Park-but Family Order forbids it.

Cleon. Such a Moon-light Night is extremely delightful indeed! The Poets were fenfible of this, and have nobly described the Pleafures thereof. Thus antient Homer,

So when the Moon, refulgent Lamp of Night,
O'er Heav'n's clear Azure Spreads her facred Light;
When not a Breath disturbs the Deep ferene,
And not a Cloud o'ercafts the folemn Scene;
Around her Throne the vivid Planets roll,
And Stars unnumber'd gild the glowing Pole,
O'er the dark Trees a yellower Verdure fhed,
And tip with Silver ev'ry Mountain's Head;
Then fhine the Vales, the Rocks in Profpect rife;
A Flood of Glory burfts from all the Skies;
The confcious Swains, rejoicing in the Sight,
Eye the blue Vault, and bless the ufeful Light.

DIALOGUE

II.

Of the MOONS or SATELLITES of JUPITER and

SATURN.

Cleonicus.

W this' Evening? you

ELL, Euphrofyne, how are you difpofed to spend this Evening? you fee 'tis like to be a very

fine one.

Euphrof. You seem, Cleonicus, to represent the Evening as inviting to a Walk; than which nothing will be more agreeable to me, if you are so inclined.

Cleon. You know, Sifter, my Inclinations were always to gratify you in every Thing in my Power.

Euphrof. You are very good for that indeed, Cleonicus; but which Way will a Walk be moft agreeable? Shall we take a Tour round the Park, or (as we have sometimes done) over the green Corn Fields to that yonder pleasant Hill?

Cleon. The Moon will make the Avenues of the Park extremely agreeable; but the Hill will fuit with our Defign beft To-night, which you know was to take a more particular Survey of the Moons which attend Jupi

ter and Saturn.

Euphrof. Let that determine us then; I believe we fhall have equal Pleasure in going that Way: Are you ready to walk?

Cleon. I have only the Telescope to take, and then I am.

Euphrof. You are now ready, I fee.-But as we go forward, pray, Cleonicus, give me fome more particular Account of the Moons, which you fay attend Jupiter and Saturn? and also the Reason why fome Planets have Moons, and others none?

Cleon. The Planets Mercury and Venus have no Moons, because they cannot be fuppofed to want any in fuch Vicinity to the Sun; and as to Mars, there has been none difcovered about him, and it is very likely he has none; either because there may be no Inhabitants there, (for he is a finall Planet, and of a different Afpect from all the Reft) or else they may be fupplied with Light, by Night, fome other Way; perhaps by a native Lustre of the Earth or Soil of that Planet, which may fhine in the Abfence of the Sun, like fome natural Phosphers with us. The Almighty can effect the fame Things by more Ways than one, and generally fhews his boundless Power and Wisdom by an infinite Variety of Methods he often takes to display it.

Euphrof. Well, it feems Jupiter and Saturn have Moons enough to afford us a Subject of Speculation Tonight. Pray, by whom, and how long have they been discovered?

Cleon. The Moons or Satellites of Jupiter were difcovered first of all by one Galileo, a famous Italian Philofopher, who (as himself tells us) in the Year 1610, on the 7th of January, at Night, faw three fmall bright Stars very near Jupiter, two on the Eaft Side, and one on the Weft; thefe he took to be fixed Stars at that Time, but happening the next Night to view them again, he faw them all three on the Weft Side of Jupiter, which made him greatly wonder how this could be, for it was an Event quite inconfiftent with the Theory of the Planets and fixed Stars. On the 10th Night he faw but two, and both on the Eaft of Jupiter; on the 11th also he faw but two, and both on the fame Side; but one of these was twice as large as the other; and thence he was fure they were not the fame he faw the Night before. On the 13th Night, viewing them again, he faw four of these small Stars, three on the Weft Side of Jupiter, and

one

one on the East Side; all nearly in a strait Line. Thefe were all he could ever difcover, and by conftantly obferving their Situation and Changes, found they were not fixed Stars, but Moons, or fecondary Planets, revolving about Jupiter, in the fame Manner as the primary Planets revolve about the Sun. To these he first gave the Title of Medicean Stars, in Honour of the Family of the Medici, who were his Patrons.

Euphrof. No Doubt but this new Difcovery was very agreeable News to the Aftronomers, and gratefully received by them.

Cleon. Surprisingly fo; it is not eafy to imagine with what Eagerness they all haftened to view the new Wonder. Jupiter had now more Addresses than when he was efteemed a Deity; every one being willing to see the new-difcovered Equipage and Attendants of this great Lord; 'till at length their Motions became fo well obferved, as to be found regular and conftant, and fo became reduced to a Theory, as perfect as that of the Moon, or larger Planets.

Euphref. Why then, I fuppofe, you can tell their Distances from Jupiter, the Times of their Revolutions about him, &c.

Cleon. Yes, very well. For, by the Theory, the nearest Satellite to Jupiter is diftant from him about one hundred eighty-eight thousand Miles, and performs its Revolution in one Day, 18 Hours, and 27 Minutes. The fecond is diftant from Jupiter about three hundred and twenty thousand Miles, and its Period is three Days, 13 Hours, and 13 Minutes. The third Satellite is diftant about five hundred and thirty-fix thousand Miles, and its Period is feven Days, three Hours, and 43 Minutes. The fourth, or utmoft Satellite, is diftant about nine hundred and feventy-two thousand Miles, and its Period is in 16 Days, 16 Hours, and 32 Minutes.

Euphrof. Then I find that two of thofe Moons are nearer to Jupiter than our Moon is to us; and two of them farther distant from him than ours from the Earth.

Cleon. Very true; and at the fame Time you observe, that the periodical Time of our Moon is greater than any of his.

Euphrof. I do: And now, if you pleafe, I fhall be glad to hear the fame Account of Saturn's Moons.

Cleon. The first who obferved the Satellites of Saturn, was Hugenius, a Dutch Conful, who in the Year 1655 difcovered one, which is the fourth from Saturn. But, as I have told you, Saturn has five Moons, and all the other four were difcovered by Signior Caffini, an Italian: the third and fifth in the Year 1671, and the two innermoft in the Year 1686. He called them the Lodovicean Stars, in Honour of Lewis the Great, in whofe Reign they were discovered.

Euphrof. And is the Theory of thefe Moons as certain as thofe of Jupiter?

Cleon. They are not fo eafily obferved as Jupiter's, by Reafon of their great Distance from us; but the induftrious Aftronomers have found their Distance from Saturn, and the Time of their Revolutions, as follow:

The first Satellite is diftant from Saturn about eightytwo thousand Miles, and his Period is one Day, 21 Hours, and 18 Minutes.

The fecond is diftant about one hundred and feventyfive thousand Miles, and its Period is two Days, 17 Hours, and 41 Minutes.

The third is diftant about two hundred and fifty-four thousand Miles, and its Period is in four Days, 12 Hours and 25 Minutes.

The fourth is diftant about fix hundred and forty-nine. thousand Miles, and its Period is 15 Days, 22 Hours, and 41 Minutes.

The fifth is diftant about nineteen hundred and fixty-four thousand Miles, and its Period is 79 Days, feven Hours, and 48 Minutes.

Euphrof. Why then I find that fome of Saturn's Moons are much nearer, and others much farther from him than are thofe of Jupiter from him.

Cleon. They are fo. † And now, Sifter, we are come to the End of our Walk; we will take a particular View of thofe Moons with this excellent reflecting Telescope, and you will fee that fo true is the Theory of thefe fecon

dary

To give the Reader a better Idea of this Syftem of Saturnian Moons, I have drawn them all out at fuch Distances as they have from the Center of their Primary in the Heavens, together with the proportional Magnitude of Saturn and his Ring, in Plate XIV.