have they any Clouds to obſtruct their View, ſo that it is eaſier for them to find out the Courſes of the Planets, but more difficult to make a true Syſtem of them. For they will be apt to lay a wrong Foundation, by ſuppoſing that their Earth ſtands ſtill, which will lead them into more dangerous Errors than [This may be applied to the Moons about Jupiter and Saturn.] ever it did us. All that I have ſaid belongs as well to Jupiter’s and Saturn’s Satellites as to our Moon, in reſpect of the Planets they move round. The Length of their Day and Night is always equal to the Time of their Revolution: For example, the fifth Moon moves round Saturn in 80 Days, and the Days and Nights there are equal to Forty of ours. Both their Summer and Winter (Saturn moving round the Sun in thirty Years) are fifteen Years long. Therefore it is impoſſible but that their way of living muſt be very different from ours, having ſuch tedious Winters, and ſuch long watching and ſleeping times. Having thus explained the primary and ſecondary Planets round the Sun, we ſhould next ſet about the third Sort, the Sun and fix’d Stars; but before we do that, it would be worth while to ſet before you at once, in a clearer and more plain Method than hitherto, the Magnificence and Fabrick of the Solar Syſtem. Which we can’t poſſibly do in ſo ſmall a Space as one of our Leaves will but admit of, becauſe the Bodies of the Planets are ſo prodigiouſly ſmall in companion of their Orbs. But what is wanting in Figure ſhall be made up in Words. Going back then to the firſt Scheme, ſuppoſe another [Fig. 1.] like it, and proportionable, drawn upon a very large ſmooth Plain; whoſe outermoſt Circle repreſenting the Orb of Saturn, muſt be conceived three hundred and ſixty Foot in Semidiameter. In which you muſt place the Globe and Ring of Saturn of that [Fig. 2.] Bigneſs as the 2d Figure ſhows you. Let all the other Planets be ſuppoſed every one in his own Orbit, and in the middle of all the Sun, of the ſame Bigneſs that That Figure repreſents, namely, about four Inches in Diameter. And then the Orbit or Circle in which the Earth moves, which the Aſtronomers call the Magnus Orbis, muſt have about ſix and thirty Foot in Semidiameter. In which the Earth muſt be conceived moving, not bigger than a grain of Millet, and her Companion the Moon ſcarcely perceivable, moving round her in a Circle a little more than two Inches Diameter, as in [Fig. 5.] the Figure here adjoined, where the Line A B repreſents a ſmall portion of that Circle which the Earth moves in: the ſmall Circle therein C is the Earth, and the Circle D E the Path of the Moon round it, in which the Body of the Moon is D. The outermoſt of Saturn’s Moons moves in an Orbit whoſe Semidiameter is 29 Inches; that of Jupiter in a ſomewhat ſmaller, whoſe Semidiameter is 19 and a quarter.