and per influx, a For it is Thus the great Creator hath made the moon to be of admirable ufe to our earth. And fo wifely hath he contrived his works, that they are mutually ferviceable to one another, so that what good fervices one doth, the other as readily returneth again. Thus, as the moon is a moon to us, fo the earth is with great reafon concluded by the philofophers, to be a moon to the moon ; not indeed a fecondary planet moving periodically about her, but fuch a planet, as reflects the light of the fun to her, haps makes fuch like returns of as I faid the earth receives from her. not to be doubted, if the earth reflects light, and gravitates to the moon, as well as the moon to the earth (which is highly probable), but that there is a mutual intercourfe and return of their influences, and good offices. And this is ftill more probable from the likeness difcernible between the earth and the moon, which is a ftrong prefumption that the moon may have the fame occafions for the earth, as the earth for her. For that fhe is an opake body, and that her furface is covered in fome measure with hills and valleys is manifeft beyond all doubt to our eye, as I before See Book v. chap. z. note (r) p. 298. before said: and that the hath an atmosphere, is what hath been not long fince b difcovered: and that there are large oceans and collections of water, is what I have before made probable . And therefore, agreeing thus in conftitution and make, their occafions for, and influences upon each other, are in all probability mutual, and much the fame. And after this manner, the infinitely wife Contriver of the universe seems to have transacted throughout that immenfe space, by making all the feveral globes useful to one another. Thus all the planets of our folar fyftem are of confiderable ufe to us, all of them reflect light unto us, and fome of them a light fo bright and ftrong, as particularly Venus and Jupiter, that they are a good fupply of the moon's abfence in the night, as well as the fun's. Nay, the very fecondaries (which I fhail fhew are of greateft ufe to their primary planets) have their ufes too amongst us; not only as being evident demonftrations of the great works of God, but alfo in miniftering to the difcovery of the longitude of the most diftant places • See before chap. 3. note (v) • Book v. chap. 4. note (e) as alfo the Preface. places upon the earth. So for the fixt ftars, which I have before fhewn to be probably so many funs ministering to as many systems of planets; it is certain they are of great ufe to us in fupplying the absence of the fun and moon by night. And there is no great doubt to be made, but that the like returns are made to them and their systems by our fun. So that here we have an admirable oeconomy obfervable throughout all the visible regions of the univerfe, in the natural affiftances and returns which one globe affords the other, even at the greatest distance. CHAP. CHA P. V. OF THE MOONS, OR SECONDARY PLANETS IN GENERAL, WHICH ARE OBSERVED ABOUT SOME AVING taken a view of the methods which HAVING are used for the accomodating the Earth with light and heat, let us caft our eye to the reft of our Solar fyftem, and examine whether any thing of the like kind is to be found there. And here we fhall find a no lefs admirable scene of the great Creator's care and wifdom, than we discovered in the Earth and Moon. In Mars, indeed, we can difcern a great fimilitude with the Earth in its opacity and fpots, but we have not yet been able to perceive any attendance of Moons, as in the other fuperior planets; not fo much probably becaufe there are none, but because they are small, or they reflect a weak light, and are at a great distance from us. And as for Venus and Mercury there may be no occcafion for any attendants, by reafon of their proximity to the Sun. But in the two higheft or more diftant planets, Jupiter and Saturn, we have a very noble and entertaining fcenc of the Creator's glory. For whereas thofe two planets are at a much greater diftance than any of the other planets, from their fountain of light and heat, the Sun; and as confequently their heat and light are abated in proportion to the fquare of their distances; fo, to make them amends, they are furrounded with a more grand retinue of fecondary planets, or Moons; Jupiter with four, Saturn with five, as it is imagined, and probably more d And an admirable remedy this is, not only for the great distance of these two planets from the Sun, but alfo for the tardity of the periodick mo Mr. Huygens, in his Cofmotheoros, p. 99. gives this account of the difcovery of the fatellites of Jupiter and Saturn. That it is well known the discovery of the circumjovials is owing to Galilæo; that the brighteft, and outermoft circumfaturnial he happened to fee with a 12 foot glafs in the year 1655: that the rest are owing to Caffini, who firft faw them with a glafs of Campani's grinding of 36 feet, and afterwards with one of as many feet above 100. That the 3d and 5th Caffini fhewed him in 1672, and afterwards oftener. That Caffini acquainted him by letter afterwards with his difcovery of the first and fecond in 1684. That the two laft are not eafily difcerned, and he cannot fay he ever faw them. That befides thefe five, he fufpects there may be one or more lye concealed. Of which fce ch. vii. following. |