Book II


New Conjectures concerning
the Planetary Worlds

BOOK the Second

’T WAS a pretty many years ago that I chanc’d to light upon Athanasius Kircher’s Book, call’d, The Ecstatick Journey, which treats of the nature of the Stars, and, of all things that are to be found in the Planets: I wonder’d to see nothing there of what I had often thought not improbable, but quite other things, nothing but a company of idle unreasonable stuff: which I was the more confirm’d in, when, after the writing of the former part, I ran over the Book again. And methoughts mine were very notable weighty Matters if but compar’d with Kircher’s. That other People may be satisfied in this, and see how vainly those, who cast off the only Foundations of Probability in such matters, which we have all the way made use of, pretend to philoso[102]phize in this case, I don’t care if I bestow some few Reflections upon that Book.

Kircher’s Journey in Ecstacy examin’d

That ingenious Man supposing himself carry’d by some Angel through the vast spaces of Heaven, and round the Stars, tells us, he saw a great many things, some of which he had out of the Books of Astronomers, the rest are the product: of his own Fancy and Thoughts. But, before he enters upon his Journey, he lays down these two things as certain; that no Motion must be alIow’d the Earth, and that God has made nothing in the Planets, no not so much as Herbs, which has either Life or Sense in it. Leaving then the System of Copernicus, he chuses Tycho for his Guide. But when he supposes all the fix’d Stars to be Suns, and round each of them places their Planets, here (against his will I suppose) he has unawares made an infinite number of Copernican Systems. All which, besides their own Motion, he absurdly makes to be carry’d, with a monstrous swiftness, in twenty four hours, round the Earth. When most of these Worlds are out of the reach [103] of any Man’s sight, as he owns they are, I cannot think for what he makes so many Suns to shine upon desolate Lands (like our Earth in every thing, he says, only that they have neither Plants nor Animals) where there’s no one to whom they should give light. And from hence he still falls into more and more Absurdities. And because he could find no other use of the Planets, even in our System, he is forc’d to beg help of the Astrologers; and would have all those vast Bodies made upon no other account than to preserve and rule the inferior World by, and govern the Mind of Man by their various and regular Influences. Accordingly, to gratify Astrology, he says that Venus was the prettiest pleasant place, every thing fine and handsom, its Light gentle, its Waters sweet and purling, and it self beset all about with shining Crystals. In Jupiter he found wholesom and sweet Gales, delicate Waters, and a Land shining like Silver. For from these two Planets forsooth, Men have all that is happy and healthful poured down upon them; and all that renders [104] them handsom and lovely, wise and grave, is owing to their Influences. Mercury had I don’t know what ye call’t, Airiness and Briskness about him; whence Men derive, when they are first born, all their Wit and Cunning. Mars was nothing but devilish, infernal, stinking, black Flames and Smoke: and Saturn was all melancholy, dreadful, nasty, and dark: for these are the Planets (I don’t know why, but all your Fortune-tellers hate them) that bring all the Plagues and Mischiefs that we feel upon us, and would exercise their spite still more, except they were sometimes mitigated and corrected by the benign and kind Influences of the other Planets. All this fine stuff his Genius teaches him. Which he makes give a serious Answer to this idle Question, Whether a Jew or Heathen could be duly and rightly baptiz’d in the Waters of Venus? Of him too he learns that the Heaven of the fix’d Stars is no solid stuff: but a thin fluid, wherein an innumerable company of Stars and Suns lie floating here and there, not chain’d down to any place, (thus far he’s in [105] the right) and making in the space of a day that prodigious Tour round the Earth. He forgets here, if there were such a Motion, with what an incredible swiftness they would fly out from their Centers. But I suppose the Intelligences that he has plac’d in them will take care of that, those Angels that preside over, and regulate their Motions. And in that he follows a company of Doctors that harbour’d that idle fancy of Aristotle upon no account or consideration. But Copernicus has set them all at liberty, only by bringing in the Motion of the Earth: which, if upon no other account, every one that is not blind purposely must own to be necessary upon this. I dare say Kircher, if he had dar’d freely to speak his mind, could have afforded us otherguess things than these. But when he could not have that liberty, I think he might as well have let the whole matter alone. But enough, let’s have done with this famous Author: And now that we have ventur’d to place Spectators in the Planets, let’s take a Journey to each of them, [106] and see what their Years, Days, and Astronomy are.

The System of the Planets in Mercury

To begin with the innermost and nearest the Sun: We know that Mercury is three times nearer that vast body of Light than we are. Whence it follows that they see him three times bigger, and feel him nine times hotter than we do. Such a degree of Heat would be intolerable to us, and set afire all our dry’d Herbs, our Hay and Straw that we use. And yet I warrant the Animals there, are made of such a temper, as to be but moderately warm, and the Plants such as to be able to endure the Heat. The Inhabitants of Mercury, it’s likely, have the same opinion of us that we have of Saturn, that we mull be intolerably cold, and have little or no Light, we are so far from the Sun. There’s reason to doubt, whether the Mercurians, tho they live so much nearer the Sun, the Fountain of Life and Vigour, are much more airy and ingenious than we. For if we may guess at them by what we see here, we shall not be obliged to grant it [107] the Inhabitants of Africa and Brasil, that have got for their share the hottest places in the Earth, being neither so wise nor so industrious as those that belong to colder and more temperate Climates; they have scarce any Arts or Knowlege among them, and those of them that live upon the very shore, understand little or no Navigation. Nor can I be willing to make all that vast: number that must inhabit those two large Planets, Jupiter and Saturn, and have such noble Attendance, mere dull Blockheads, or without as much Wit as our selves, tho they are so far more distant from the Sun. The Astronomy of the Mercurials, and the appearance of the Planets to them, opposite at certain times to the Sun, may be easily conceived by the Scheme of the Copernican System in the former Part. At the times of these Oppositions Venus and the Earth must needs appear very bright and large to them. For if Venus shines so gloriously to us when she is new and horned, she must necessarily in opposition to the Sun, when she is full, be at least six or se[108]ven times larger, and a great deal nearer to the Inhabitants of Mercury, and afford them Light so strong and bright, that they have no reason to complain of their want of a Moon. What the length of their Days are, or whether they have different seasons in the Year, is not yet discover’d, because we have not yet bin able to observe whether his Axis have any inclination to his Orbit, or what time he spends in his diurnal Revolution upon himself. And yet seeing Mars, the Earth, Jupiter and Saturn, have certainly such Successions, there’s no reason to doubt but that he has his Days and Nights as well as they. But his Year is scarce the fourth part so long as ours.

In Venus

The Inhabitants of Venus have much the same face of things as those in Mercury, only they never see him in opposition to the Sun, which is occasioned by his never removing above 38 degrees, or thereabouts, from it. The Sun appears to them by half larger in his Diameter, and above twice in his Circumference, than to [109] us: and by consequence affords them but twice as much Light and Heat, so that they are nearer our Temperature than Mercury. Their Year is compleated in seven and a half of our Months. In the Night our Earth, when ’tis on the other side of the Sun from Venus, must needs seem much larger and lighter to Venus than she doth ever to us; and then they may easily see, if they have not very weak eyes, our constant Attendant the Moon. I have often wonder’d that when I have viewed Venus at her nearest to the Earth, when she resembled an Half-moon, just beginning to have something like Horns, through a Telescope of 45 or 60 Foot long, she always appeard to me all over equally lucid, that I can’t say I observ’d so much as one spot in her, tho in Jupiter and Mars, which seem much less to us, they are very plainly perceived. For if Venus had any such thing as Sea and Land, the former must necessarily show much more obscure than the other, as anyone may satisfy himself, that from a very high Mountain will [110] but look down upon our Earth. I thought that perhaps the too brisk Light of Venus might be the occasion of this equal appearance; but when I used an Eye-glass that was smok’d for the purpose, it was still the same thing. What then, must Venus have no Sea, or do the Waters there reflect the Light more than ours do, or their Land less? or rather (which is most probable in my opinion) is not all that Light we see reflected from an Atmosphere surrounding Venus, which being thicker and more solid than that in Mars or Jupiter, hinders our seeing any thing of the Globe it self, and is at the same time capable of sending back the Rays that it receives from the Sun? For it’s certain that if we look’d on the Earth from the outside of the Atmosphere, we should not perceive such a difference as we do from a Mountain; but by reason of the interposed Atmosphere, we should observe very little disparity between Sea and Land. ’Tis the same thing that hinders us from seeing the spots in the Moon as plain in the day as in the [111] night, because the Vapors that surround the Earth being then enlightned by the Rays of the Sun, are an impediment to our prospect.

In Mars

But Mars, as I said before, has some Parts of him darker than other some. By the constant Returns of which his Nights and Days have bin found to be of about the same length with ours. But the Inhabitants have no perceivable difference between Summer and Winter, the Axis of that Planet having very little or no inclination to his Orbit, as has bin discover’d by the Motion of his Spots. Our Earth must appear to them almost as Venus doth to us, and by the help of a Telescope will be found to have its Wane, Increase, and Full, like the Moon: and never to remove from the Sun above 48 Degrees, by whose discovery they see it, as well as Mercury and Venus, sometimes pass. They as seldom see Venus as we do Mercury. I am apt to believe, that the Land in Mars is of a blacker hue than that of Jupiter or the Moon, which is the reason of his appearing of a Copper Colour, and his [112] reflecting a weaker Light than is proportionable to his distance from the Sun. His Body, as I observ’d before, tho farther from the Sun, is less than Venus. Nor has he any Moon to wait upon him, and in that, as well as Mercury and Venus, he must acknowlege himself our inferiour. His Light and Heat is twice, and sometimes three times less than ours, to which I suppose the Constitution of his Inhabitants is answerable.

Jupiter and Saturn the most eminent of the Planets both for bigness and attendants

If our Earth can claim preeminence of the fore-mentioned Planets for having a Moon to attend upon it, (for its Magnitude can make but a small difference) how much superiour must Jupiter and Saturn be to all four of them, Earth and all? For whether we consider their bulk, in which they far exceed all the others, or the number of Moons that wait upon them, it’s very probable that they are the chief, the primary Planets in our System, in comparison with which the other four are nothing, and scarce worth mentioning. For the easier conception of their vast disparity, I have thought fit

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[113] to add a Scheme of our Earth, with the Path of the Moon about it, and the Globe of the Moon it self; and the Systems of Jupiter and Saturn, where I have drawn every thing as near the true Proportion as possible. Jupiter you see has his four, and Saturn his five Moons about him, all plac’d in their Orbits. The Jovial we owe to Galiléo, ’tis well known: and anyone may imagine he was in no small rapture at the discovery. The outermost but one, and brightest of Saturn’s, it chanc’d to be my lot, with a Telescope not above 12 foot long, to have the first sight of in the year 1655. The rest we may thank the industrious Cassini for, who used the Glasses of Jos. Campanus’s Work, first of 36, and afterwards of as many above 100 foot long. He has often, and particularly in the year 1672, show’d me the third and fifth. The first and second he gave me notice of by Letters in the year 1684. but they are scarce ever to be seen, and I can’t positively say I had ever that happiness: but am as satisfied that they are [114] there, as if I had; not in the least suspecting the Credit of that worthy man. Nay, I am afraid there are one or two more still behind, and not without reason. For between the fourth and fifth there’s a distance not at all proportionable to that between all the others: Here for ought I know may lurk a sixth Gentleman; or perhaps there may be another without the fifth that may yet have escaped us: for we can never see the fifth but in that part of his Orbit, which is towards the West: for which we shall give you a very good reason.

Perhaps when Saturn comes into the Northern Signs, and is at a good height from the Horizon (for at the writing of this he is at his lowest) you may happen to make some new Discoveries, good Brother, if you would but make use of your two Telescopes of 170 and 210 foot long; the longest, and the best I believe now in the World. For tho we have not yet had an opportunity of observing the Heavens with them (as well by reason of their unwieldiness, as for [115] the interruption of our Studies by your absence) yet I am satisfied of their Goodness by our trial of them one night, in reading a Letter at a vast distance by the help of a Light. I cannot but think of those times with pleasure, and of our diverting labour in polishing and preparing such Glasses, in inventing new Methods and Engines, and always pushing forward to still greater and greater things. But to return to those Diagrams.

The proportion of the Diameter of Jupiter, and of the Orbs of his Satellites, to the Orbit of the Moon round the Earth

I have there made the Diameter of Jupiter about two third parts of our distance from the Moon: for the Diameter of Jupiter is above twenty times bigger than that of the Earth; which the distance of the Moon contains about thirty times. The Orbit of the outermost of Jupiter’s Guards is to that of the Moon round the Earth, as 8 and ½ is to 1. And each of these Moons, by the shadow they make upon Jupiter, cannot be less than our Earth.

The periods of Jupiter’s Moons

Their Periods, that I may not omit them, are according to Cassini’s account these. That of the inmost is one day, 18 hours, 28 minutes, [116] and 36 seconds. The second spends 3 days, 13 hours, 13 min. 52 sec. in going round him. The third 7 days, 3 hours, 59 min. 40 sec. The fourth 16 days, 18 hours, 5 min. 6 sec. The distance of the innermost from Jupiter himself is 2 5/6 of his Diameters. That of the second is 4 and a half: Of the third 7 and one sixth part: Of the fourth 12 and two thirds, of the same Diameters.

And Saturn’s

The innermost of Saturn�s Guards moves round him in 1 day, 21 hours, 18 min. 31 sec. The second in 2 days, 17 hours, 41 min. 27 sec. The third in 4 days, 11 hours, 47 min. 16 sec. The fourth in 15 days, 22 hours, 41 min. 11 sec. The fifth in 79 days, 7 hours, 53 min. 57 sec. Their distances from the Center of Saturn are, that of the first almost one, that is 39 fortieth parts of the Diameter of his Ring; that of the second one and a quarter of those Diameters; of the third one and three quarters of them; of the fourth four, or according to my calculation, but 3 and a half; of the fifth 12, which were found with vast pains and labour.

[117] Now can any one took upon, and compare there Systems together, without being amazed at the vast Magnitude and noble Attendance of there two Planets, in respect of this little pitiful Earth of ours? Or can they force themselves to think, that the wise Creator has disposed of an his Animals and Plants here, has furnish’d and adorn’d this Spot only, and has left all those Worlds bare and destitute of Inhabitants, who might adore and worship him; or that all those prodigious Bodies were made only to twinkle to, and be studied by some few perhaps of us poor fellows?

This proportion true according to all modern Observations

I do not doubt but there will be some who will think we Romance very much about the Magnitude of these Planets. For will you pretend to make them who are taken up in admiring the largeness of this Globe, its multitude of Nations, Cities, and Empires; can you pretend I say to make them ever believe that there are Places in comparison of which the Earth is as inconsiderable as my Figure would make it? No, they know better things [118] they’l cry. But they may vouchsafe to be inform’d, that these Proportions are those which the best Astronomers of this Age have agreed upon. For if the Earth be distant from the Sun ten or eleven thousand of its own Diameters, according to the accounts of Monsieur Cassini in France, and Mr. Flamsted in England, wherein they made use of very exact Observations of the Parallaxes of Mars; or if, according to a very probable Conjecture of mine, it be distant twelve thousand, then the Magnitudes of the other Orbs will very near answer the Proportions here settled.

The apparent magnitude of the Sun in Jupiter, and a way of finding what light they there enjoy

But to return to Jupiter. The Sun appears to them five times less than to us, and consequently they have but the five and twentieth part of the Light and Heat that we receive from it. But that Light is not so weak there as we imagine, as is plain by the brightness of that Planet in the Night; and that when the Sun is so far eclips’d to us, as that the 25th part of his Disk be not free from the Shadow, he is not sensibly darken’d. But if you have a [119] mind exactly to know the quantity of light that Jupiter enjoys, you may take a Tube of what length you please. Let one end of it be clos’d with a Plate of Brass, or any such thing, in the middle of which there must be a hole, whose breadth must have the same proportion to the length of the Tube, as the Chord of 6 Minutes bears to the Radius; that is about as one is to 570. Let the Tube be turn’d so to the Sun, that no Light may fall upon a white Paper plac’d at the end of it, but what comes through the little hole at the other end of the Tube. The Rays that come through this will represent the Sun upon the Paper of the same Brightness that the Inhabitants of Jupiter see it in a clear day. And if removing the Paper you place your eye in the same place, you will see the Sun of the same Magnitude and Brightness as you would were you in Jupiter.

And in Saturn

If you make the hole twice as little in breadth, you will see the same of Saturn. And altho his Light be but the hundredth part of ours, yet you [120] see it makes him shine finely in a dark night. But in cloudy days what shall the poor Inhabitants do? Why if we were to be Judges but miserably, but yet I warrant they do not at all complain. Perhaps they may be like Owls and Bats, and may love the Twilight better than open day.

In Jupiter their days are 5 hours

But it’s a little strange, that when Jupiter is so much bigger than our Planet, their Days and Nights should be but five of our Hours. By this we may see that Nature has not observ’d that proportion that their bulk seems to require, seeing in Mars the days are very little different from ours. But in the length of their years, that is in the revolution of the Planets round the Sun, there is an exact proportion to their distances from the Sun followed. For as the Cubes of their distances, so are the Squares of their Revolutions, as Kepler first found out. Which proportion the Moons of Jupiter and Saturn keep in their Courses round those.

Always the same length

As the Years and Days in Jupiter are different from ours in this respect, so are the Days in another; [121] namely, that they are all of the same length. For they there enjoy a perpetual Equinox, their Axis having little or no inclination to their Orbit, as the Earth’s has, as has bin discover’d by Telescopes. The Countries that lie near their Poles have little or no heat, by reason the Rays of the Sun fall so obliquely upon them; but then they are freed from the Inconveniency that ours are troubled with, of tedious long half-year Nights, and have the constant returns of Day and Night every five hours. Indeed we should not be contented with such short days, and should count our selves very ill dealt with if we had not twice as long, tho upon no other account, but that what is our own, to be sure, must be best.

The rest of the Planets are so near the Sun, (Mars himself never being above 18 degrees from it) that in Jupiter they have the sight only of Saturn. But we cannot deny but that their four Moons stand them in greater stead than our one doth us, if ’twere only that they seldom know any such thing as to be without Moonshiny [122] Nights. And they are of great advantage to them, as we said before, in their Navigation, if they have any such thing. Not to mention the pleasant sights of their frequent Conjunctions and Eclipses, things that they are seldom a day without.

Saturn enjoys all those Pleasures and Advantages in a still higher degree, as well for his five Moons, as for the delightful prospect that the Ring about him affords his Inhabitants night and day. But we will be as kind to them as we have bin to the rest of the Planets, in giving an account of their Astronomy.

They see the fixt Stars just as we do

And first of all we shall observe what we might have remark’d before, but will be more strange here, that the fix’d Stars appear to them of the same Figure and Magnitude, and with the same degree of Light that they do to us: and this, by reason of their immense distance, of which we shall have occasion to speak by and by. In comparison with which the space that a Bullet shot out of a Cannon could travel in 25 years, would be almost nothing.

[123] Their Astronomers have all the same Signs of the Bear, the Lion, Orion, and the rest, but not turning upon the same Axis with us: for that’s different in all the Planets.

As Jupiter can see no Planet but Saturn, so Saturn knows of no Planet but Jupiter; which appears to him much as Venus doth to us, never removing above 37 degrees from the Sun. The length of their days I cannot determine: But if from the distance and period of his innermost Attendant, and comparing it with the innermost of Jupiter’s, a Man may venture to give a guess, they are very little different from Jupiter’s, 10 hours or somewhat less. But whereas in Jupiter there are equally divided between Light and Darkness, the Saturnians must perceive a more sensible difference than we, especially between Summer and Winter. For our Axis inclines to the place of the Ecliptick but 23 degrees and a half, but theres above 31. Upon this account his Moons must decline very much from the Path that the Sun seems to move [124] in, and his Inhabitants can never have a full Moon but just at the Equinoxes: two of which fall out in 30 of our years. Tis this Position of the Axis too that is the cause of those delightful appearances, and wonderful prospects that its Inhabitants enjoy: for the better understanding of which I shall draw a Figure of Saturn with his Ring about him: in which the proportion between the Diameters of the Globe and Ring is as 9 to 4. And the empty space between them is of the same breadth with the Ring it self. All Observations conspire to prove that that is of no great thickness, altho if we should allow it six hundred German Miles, I think, considering its Diameter, we should not overdo the matter.

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Suppose then that to be the Globe of Saturn, whose Poles are A, B. GN is the Diameter of the Ring, as you view it sideways, representing a narrow Oval. Those that live about the Poles within the Arches CAD, EBF, each of which are 54 degrees, (if the Cold will suffer any body to live [125] there) never have a sight of the Ring.

The appearances of the Ring in Saturn

From all other parts it is continually to be seen for fourteen years and nine Months, which is just: half their year. The other half it is hid from their view. Those then that dwell between the Polar Circle CD, and the Equator TV, all that time that the Sun enlightens the part opposite to them, have every night the sight of a piece of it HGL, much in the shape of a shining Bow, which comes from the Horizon, but is darken’d in the middle by the shadow of Saturn GH, which reaches most commonly to the outermost rim of it. But after midnight that Shadow by little and little begins to move towards the right hand to those in the Northern, but the left to those in the Southern Hemisphere. In the morning it disappears, leaving behind it a likeness indeed of a Bow, but much paler and weaker than our Moon is in the day-time. For they, as I said before, have an Atmosphere, or an Air surrounding them enlighten’d by the Sun. Otherwise Night and Day they would have their Ring, [126] their Moons, and all the fix’d Stars, equally conspicuous. Another thing that must make the sight of their Ring very curious, is, that by some Spots in it, it is discover’d to turn round upon it self: A thing that those that are so near cannot but take notice of, when we that live at this distance can descry a great Inequality, the inside of it being brighter much than the outside is. When the shadow of the Globe falls upon that part of the Ring GH, the shadow of the Ring at the same time darkens another part of the Globe about PF, which otherwise would have the Sun upon it. So that there is always a Zone of the Globe PYFE, sometimes of a larger extent than at others, which is depriv’d of the sight both of the Sun and Ring for a considerable time, the latter of which hides some, part of the Stars from it too. An amazing thing it must be, all of a sudden to have the Sun darken’d, and, fall into a pitch-night, without seeing any cause of such an accident. All which while their Moons are their only Comfort. The other half of the [127] year the Hemisphere TBV enjoys the same Light that TAU before did, and then this undergoes those long Eclipses that that before suffer’d. At the Equinoxes, when the Sun is in the same Plane with the Ring, the Saturnians cannot well perceive it: no not even we with our Glasses, by reason of its Darkness. This happens when Saturn, viewed from the Sun, is advanced one and twenty degrees and a half in Virgo or Pisces, as I show’d formerly in my System of Saturn: Where there is an account given of the Risings of the Sun above the Ring, throughout all the Saturnian Year.

With Saturn in this Scheme you have the Globes of the Earth and Moon drawn in their true proportion, to put you in mind again of a thing very fit to be remember’d, how very small our Habitation is when compar’d with that Globe or the Ring about it. And now anyone, I suppose, can frame to himself a picture of the Night in Saturn, with two Arches of the Ring, and five Moons shining [128] about, and adorning him. This then shall be what I have to say to the primary Planets.

We are now come a little lower, to make an enquiry into the Attendants of there Planets, especially our own. And here we shall meddle not only with their Astronomy, but shall also search into their Furniture and Ornament, if they are found to have any such thing, which we have put off considering till now.

Very little to be said of the Moon

And here one would think that when the Moon is so near us, and by the means of a Telescope may be so nicely and exactly observ’d; it should afford us matter for more probable Conjectures than any of the other remote Planets. But it is quite otherwise, and I can scarce find any thing to say of it, because I have not a Planet of the same nature before my eyes, as in all the primary ones I have. For they are of the same kind with our Earth; and seeing all the Actions, and every thing that is here, we may make a reasonable Conjecture at what we cannot see in those Worlds.


The Guards of Jupiter and Saturn of the same nature with our Moon

But this we may venture to say, without fear, that all the Attendants of Jupiter and Saturn are of the same nature with our Moon, as going round them and being carry’d with them round the Sun just as the Moon is with the Earth. Their Likeness reaches to other things too, as you’l see by and by. Therefore whatsoever we can with reason affirm or fancy of our Moon (and we may say a little of it) must be suppos’d with very little alteration to belong to the Guards of Jupiter and Saturn, as having no reason to be at all inferior to that.

The Moon hath Mountains

The Surface of the Moon then is then found, by the least Telescopes of about three or four foot, to be diversified with long Tracts of Mountains, and again with broad Valleys. For in those parts opposite to the Sun you may see the Shadows of the Mountains, and often discover the little round Valleys between them, with a hillock or two perhaps rising out of them. Kepler from the exact roundness of them would prove that they are some vast work of the rational [130] Inhabitants. But I can’t be of his mind, both for their incredible largeness, and that they might easily be occasion’d by natural Causes.

But no Sea, nor Rivers, nor Clouds, nor Airs and Waters

Nor can I find any thing like Sea there, tho he and many others are of the contrary opinion I know. For those vast Countries which appear darker than the other, commonly taken for and call’d by the names of Seas, are discover’d with a good long Telescope, to be full of little round Cavities; whose Shadow falling within themselves, makes them appear of that colour: and those large Champains there in the Moon you will find not to be always even and smooth, if you look carefully upon them: neither of which two things can agree to the Sea. Therefore those Plains in her that seem brighter than the other parts, must consist, I suppose, of a whiter sort of Matter than they.

Nor do I believe that there are any Rivers, for if there were, they could never escape our sight, especially if they run between the Hills as ours do.

Nor have they any Clouds to furnish the Rivers with [131] Water. For if they had, we should sometimes see one part of the Moon darken’d by them, and sometimes another, whereas we have always the same prospect of her.

’Tis certain moreover, that the Moon has no Air or Atmosphere surrounding it as we have. For then we could never see the very outermost Rim of the Moon so exactly as we do, when any Star goes under it, but its Light would terminate in a gradual faint shade, and there would be a sort of a down as it were about it; not to mention, that the Vapors of our Atmosphere consist of Water, and consequently that where there are no Seas or Rivers, there can be no Atmosphere. This is that notable difference between that Planet and us that hinders all probable Conjectures about it. If we could but once be sure that they had Water, we might come to an Agreement, and plant a Colony perhaps there; we might allow it then most of our other Privileges, and, with Xenophanes, furnish it with Inhabitants, Cities, and Mountains. But as ’tis, I [132] cannot imagine how any Plants or Animals, whose whole nourishment comes from liquid Bodies, can thrive in a dry, waterless, parch’d Soil.

The Conjecture of its Plants and Animals very dubious

What then, shall this great Ball be made for, nothing but to give us a little puny light in the Night-time, or to raise our Tides in the Sea? Shall not we plant some People there that may have the pleasure of seeing our Earth turn upon itself, presenting them some times with a prospect of Europe and Africa, and then of Asia and America; sometimes half, and sometimes full? What! and must all those Moons round Jupiter and Saturn be condemn’d to the same uselesness? I do not know what to think of it, because I know of nothing like them to found a Conjecture upon. And yet ’tis not improbable that those great and noble Bodies have somewhat or other growing and living upon them, tho very different from what we see and enjoy here. Perhaps their Plants and Animals may have another sort of Nourishment there. Perhaps the moisture of the Earth there is but just sufficient [133] to cause a Mist or Dew, which may be very sutable to the growth of their Herbs. Which I remember is Plutarch’s opinion, in his Dialogue upon this Subject. For in our Earth a very little Water drawn from the Sea into Dew, and falling down again upon the Herbs, would be sufficient for all our needs, without any Rain or Showers.

Jupiter’s and Saturn’s Moons turn always the same side to them

But these are mere guesses, or rather doubts, but yet they are the best we can make of this, and all those other Moons: for, as I said before, they are all of the same nature, which is proved likewise by this, that as our Moon can afford us the sight never but of one side of her, so they turn always the same face to their primary Planets. You wonder, I suppose, how we came to know so much; but ’twas no hard matter, after that Observation which I just now made, that the outermost of Saturn’s Moons can never be seen but when she is on the West-side of her Planet. The reason of which is plainly this, that one side of her is darker, and does not reflect the Light so much as the other, [134] which when it is turned towards us, we cannot see by reason of its weak Light. This always happening when ’tis East of him, and never on the other side, is a manifest proof that she always keeps the same side toward Saturn. Now since the outermost of Saturn’s and our Moon carry themselves thus to the Planets round which they move, who can well doubt it of all the rest round Jupiter and Saturn? And there’s a very good reason for it, namely, that the matter of which those Moons consist, being heavier, and more solid on the side that is averse from us, than on that which we have the sight of, does consequently fly with a greater force from the Centre of its Motion: for otherwise, according to the Laws of Motion, it should turn the same side always, not to its Planet; but to the same fixt Stars.

This Position of the Moons, in respect of their Planets, must occasion great many very pretty, wonderful sights to their Inhabitants, if they have any: which is very doubtful, but may for the present be suppos’d.


The Astronomy of the Inhabitants of the Moon

An enquiry into our Moon may serve for all the rest. Its Globe is divided into two parts, after that manner, that those who live on one side never lose the sight of us, and those on the other never enjoy it. Only those who live on the Confines of each of these lose us, and see us again by turns. The Earth to them must seem much larger than the Moon doth to us, as being in Diameter above four times bigger. But the best of it is, that night and day they see it always in the very same part of the Heaven, as if it never moved: some of them as if ’twas falling upon their heads: others somewhat above the Horizon, and others always in the Horizon, still turning upon it self, and presenting them every twenty four hours with a view of all its Countries, even of those that lie near the Poles (I could wish my self in the Moon only for the sight of them) yet unknown and undiscover’d by us. They have it in its monthly Wane and Increase, they see it half, and horned, and full, by turns, just as we do their Planet. But the Light [136] that they borrow of us is five times larger than what they pay us again. So that in dark nights that part that hath the advantage of being towards us, receives a very glorious Light, tho let Kepler say what he will, no Heat from us. Their Days are always of the same length with their Nights; and the Sun rising and setting to them but once in one of our Months, makes the time both of their Light and Darkness to be equal to 15 of our days. If their Bodies are of the same Metal with ours, those that have the Sun pretty high in their Horizon, must be like to be burnt up in such long days. For the Sun is not farther from them than he is from us. This will be the case of those that live upon the Borders of the two Hemispheres we talk’d of; but those that live under the Poles of the Moon will be just about as hot as our Whale-Fishers about Island and Nova Zemla are, in the Summer-time: who are in so little danger of being roasted, that in the middle of their Summer, in their days of three Months length, they are ready to lose their [137] fingers ends. The Poles of the Moon I call those, round which the fixt Stars seem to turn to its Inhabitants, which are different from ours, and those of the Ecliptick, altho they move round these latter, at the distance of five degrees, in a period of nineteen Years. Their Year they count by the Motion of the Stars, and their return to the Sun, and ’tis the same with ours. They can easily do it, because they have the Stars day and night, notwithstanding the Light of the Sun: for they have no Atmosphere (which is the only reason that we don’t every day enjoy the same sight) to hinder their Observations. Nor have they any Clouds to obstruct their view, so that they have an easier work than we to find out the Courses, but a more difficult to make a true System of the Planets. For they will be apt to lay a wrong Foundation upon the Immobility of the Earth, which will lead them into more dangerous Errors than ever it did us.

This may be applied to the Moons about Jupiter and Saturn

All that I have said belongs as well to Jupiter’s and Saturn’s as to our Moon in respect of [138] 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 explain’d the primary and secondary Planets round the Sun, we should next set about the third sort, the Sun and fixt Stars; but before we do that, it will 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 comparison of their Orbs. But what is wanting in Figure shall be [139] made up in Words. Going back then to the first Scheme, suppose another 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 Semi-diameter. In which you must place the Globe and Ring of Saturn of that bigness as the 2d Figure shows you.

Let all the other Planets be supposed everyone 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 broad, as in the Figure here adjoined, where the line AB represents a small portion of that Circle which the Earth moves in: [140] the small Circle therein C is the Earth and the Circle DE the path of the Moon round it, in which the body of the Moon is D.

click for a larger image

The outermost of Saturn’s Moons move in an Orbit whose Semidiameter is 29 inches; that of Jupiter in a somewhat smaller, whose Semidiameter is 19 and a quarter.

And thus we have a true and exact Description of the Sun’s Palace, where the Earth will be twelve thousand of its Semidiameters distant from him, which in German Miles makes above seventeen Millions. But perhaps we may have a clearer comprehension of this vast length, by comparing it with some very swift Motion. ’Twas a pretty fancy of Hesiod, that an Anvil let fall from the top of Heaven, reach’d the Earth the tenth day of its Journey, and in ten more arriv’d at the bottom of Hell, the end of it: so making the Earth the midway between Heaven and Hell. I shan’t make use of the Anvil, but of one as good, namely, a Bullet shot out of a great Gun, which may travel per[141]haps in a moment, or pulse of an Artery, about a hundred Fathom, as is prov’d by those Experiments that Mersennnus in a Treatise of his relates; wherein the Sound was found to extend it self eighty hundredth parts in that time.

The immense distance between the Sun and the Planets illustrated

I say then, that supposing a Bullet to move with this swiftness from the Earth to the Sun, it would spend 25 years in its passage. To make a Journey from Jupiter to the Sun, would require 125, and from Saturn thither 250 years. This account depends upon the measure of the Earth’s Diameter, which, according to the accurate Observations of the French, is 6 538 594 times six Paris feet, one degree being 57 060 of that measure. This shows us how vast those Orbs must be, and how inconsiderable this Earth, the Theatre upon which all our mighty Designs, all our Navigations, and all our Wars are transacted, is when compared to them. A very fit Consideration, and matter of Reflection, for those Kings and Princes who sacrifice the Lives of so many People, only to flatter their Ambition in being [142] Masters of some pitiful corner of this small Spot. But to return to the matter in hand, now we have given you an account of the Sun’s proportion to those Orbs and Bodies, we’ll see what more we can say of him.

No ground for Conjecture in the Sun

And there are some that have bin so civil, as to allow the Sun himself his Inhabitants. But upon what reason I cannot imagine, there being less ground for a probability in him than in the Moon. For we are not yet sure, whether he be a compact or liquid Globe; altho, if my account of Light be true, upon that account I should rather think him liquid: which his roundness and equal distribution of his Light to all parts are an Argument for. For that inequality on his Surface, which is discover’d by the Telescopes, (and that not always neither) which makes men fancy boiling Seas and belching Mountains of Fire, is nothing but the trembling Motion of the Vapors our Atmosphere is full of near the Earth; which is likewise the cause of the Stars twinkling.

The Faculæ in the Sun not easily seen

Nor could I ever have the luck to discern those [143] bright Spots they brag so much of in the Sun as well as of his dark ones, tho the latter I have very often seen; so that with very good reason I can doubt whether there’s any such thing. For, in all the exact Observations, I could never find any such pretended to be seen any where but just about his dark Spots; and it is no great wonder that those Parts which are so near the darker, should appear somewhat brighter than the rest.

By reason of its Heat no Inhabitants like ours can live in the Sun

That the Sun is extremely hot and firy, is beyond all dispute, and such Bodies as ours could not live one moment in such a Furnace. We must make new sort of Animals then, such as we have no Idea or Likeness of among us, such as we can neither imagine nor conceive: which is as much as to say, that truly we have nothing at all to say. No doubt that glorious and vast Body was made for some noble end and use, and fram’d with excellent design. And I think we all very well know and feel its Usefulness in that effusion of Light and Heat to all the Planets round it; in the preservation and happiness of all [144] living Creatures, and that not only in our Ball, but in those vast Globes of Jupiter and Saturn, not much inferior to its own. These are such great, such wise ends, that it is not strange that the Sun should have bin made, if it had bin only upon their account. For, as for Kepler’s fancy, that he hath another Office, namely, to help on the Motion of the Planets in their own Orbs, by turning them round their Axis, (which he would fain establish in his Epitome) I shall give good Reasons why I cannot assent to it.

The fix’d Stars so many Suns

Before the invention of Telescopes, Stars so it seem’d to contradict Copernicus’s Opinion, to make the Sun one of the fix’d Stars. For the Stars of the first Magnitude being esteemed to be about three minutes Diameter; and Copernicus (observing that tho the Earth changed its place, they always kept the same distance from us) having ventur’d to say that the Magnus Orbis was but a point in respect of the Sphere in which they were placed, it was a plain consequence that everyone of them that appeared any thing bright, must [145] be larger than the Path or Orbit of the Earth: which is very absurd. This is the topping Argument that Tycho Brahe set up against Copernicus. But when the Telescopes shav’d them of their fictitious Rays, and show’d ’em to us bare and naked (which they do best when the Eye-glass is black’d with Smoke) just like little shining Points, then that difficulty vanished, and the Stars might still be Suns. Which is the more probable, because their Light is certainly their own: for it’s impossible that ever the Sun should send, or they reflect it at such a vast distance. This is the opinion that commonly goes along with Copernicus’s System.

They are not all in the same Sphere

And the Patrons of it do also with reason suppose, that all these Stars are not in the same Sphere, as well because there’s no Argument for it, as that the Sun, which is one of them, cannot be brought to this Rule. But it’s more likely they are scatter’d and dispersed all over the immense spaces of the Heaven, and are as far distant perhaps from one another, as the nearest of them are from the Sun.

[146] Here again too I know Kepler is of another opinion in his Epitome of Copernicus’s System, that we mention’d above. For tho he agrees with us, that the Stars are diffus’d through all the vast Profundity, yet he cannot allow that they have as large an empty space about them as our Sun has. For at that rate, ’twas his opinion, we should see but very few, and those of very different Magnitudes: For, seeing the largest of all appear so small to us, that we can scarce observe or measure them with our best Instruments; how must those appear that are three or four times farther from us? Why, supposing them no larger than these, they must seem three or four times less, and so on till a little farther they will not be to be seen at all: Thus we shall have the sight of but very few Stars, and those very different one from another; Whereas we have thousands, and those not considerably bigger or less than one another. But this by no means proves what he would have it; and his mistake was chiefly, that he did not consider the nature of Fire, which makes it be seen at such [147] distances, and at such small Angles as all other Bodies would totally disappear under. A thing that we need go no farther than the Lamps set along the Streets to prove. For altho they are a hundred foot from one another, yet you may count twenty of them in a continued row with your eyes, and yet the twentieth of them scarce makes an Angle of six Seconds. Certainly then the glorious Light of the Stars must do much more than this; so that it’s no wonder we should see a thousand or two of them with our bare eyes, and with a Telescope discover twenty times that number. But Kepler had a private design in making the Sun thus superior to all the other Stars, and planting it in the middle of the World, attended with the Planets: a favor that he did not desire to grant the rest. For his aim was by it to strengthen his Cosmographical Mystery, that the distances of the Planets from the Sun are in a certain proportion to the Diameters of the Spheres that are inscrib’d within, and circumscrib’d about Euclid’s Polyedrical Bodies. [148] Which could never be so much as probable, except there were but one Chorus of Planets moving round the Sun, and so the Sun were the only one of his kind.

But that whole Mystery is nothing but an idle Dream taken from Pythagoras or Plato�s Philosophy. And the Author himself acknowleges that the Proportions do not agree so well as they should, and is fain to invent two or three very silly excuses for it. And he uses yet poorer Arguments to prove that the Universe is of a spherical Figure, and that the number of the Stars must necessarily be finite, because the Magnitude of each of them is so. But what is worst of all is, that he settles the space between the Sun and the concavity of the Sphere of the fix’d Stars, to be six hundred thousand of the Earth’s Diameters. For this very good reason, forsooth, that as the Diameter of the Sun is to that of the Orbit of Saturn, which he makes to be as 1 to 2000, so is this Diameter to that of the Sphere of the fix’d Stars. A mere fancy without any shadow of [149] Reason. I cannot but wonder how such things as these could fall from so ingenious a Man, and so great an Astronomer. But I must give my Vote, with all the greatest Philosophers of our Age, to have the Sun of the same nature with the fix’d Stars. And this will give us a greater Idea of the World, than all those other Opinions.

The Stars have Planets about them like our Sun

For then why may not every one of these Stars or Suns have as great a Retinue as our Sun, of Planets, with their Moons, to wait upon them? Nay there’s a manifest reason why they should. For let us fancy our selves placed at an equal distance from the Sun and fix’d Stars; we should then perceive no difference between them. For, as for all the Planets that we now see attend the Sun, we should not have the least glimpse of them, either that their Light would be too weak to affect us, or that all the Orbs in which they move would make up one lucid point with the Sun. In this station we should have no occasion to imagine any difference between the Stars, and should make no doubt if we [150] had but the sight, and knew the nature of one of them, to make that the Standard of all the rest. We are then plac’d near one of them, namely, our Sun, and so near as to discover six other Globes moving round him, some of them having others performing them the same Office. Why then shall not we make use of the same Judgment that we would in that case; and conclude, that our Star has no better attendance than the others? So that what we allow’d the Planets, upon the account of our enjoying it, we must likewise grant to all those Planets that surround that prodigious number of Suns. They must have their Plants and Animals, nay and their rational ones too, and those as great Admirers, and as diligent Observers of the Heavens as our selves; and must consequently enjoy whatsoever is subservient to, and requisit for such Knowlege.

What a wonderful and amazing Scheme have we here of the magnificent Vastness of the Universe! So many Suns, so many Earths, and every one of them stock’d with so many [151] Herbs, Trees and Animals, and adorn’d with so many Seas and Mountains! And how must our wonder and admiration be encreased when we consider the prodigious distance and multitude of the Stars?

That their distance is so immense, that the space between the Earth and Sun (which is no less than twelve thousand of the former’s Diameters) is almost nothing when compar’d to it, has more Proofs than one to confirm it. And this among the rest, If you observe two Stars near one another, as for example those in the middle of the Great Bears Tail, differing very much from one another in Clearness, notwithstanding our changing our Position in our Annual Orbit round the Sun, and that there would be a Parallax were the Star which is brighter nearer us than the other, as is very probable it is, yet whatever part of the year you look upon them, they will not in the least have altered their distance. Those that have hitherto undertook to calculate their Distance, have not bin able perfectly to [152] compass their design, by reason of the extreme niceness and almost impossibility of the Observations requisite for their purpose. The only Method that I see remaining, to come at any tolerable probability in so difficult a case, I shall here make use of. Seeing then that the Stars, as I said before, are so many Suns, if we do but suppose one of them equal to ours, it will follow that its distance from us is as much greater than that of the Sun, as its apparent Diameter is less than the Diameter of the Sun. But the Stars, even those of the first: Magnitude, tho view’d through a Telescope, are so very small that they seem only like so many shining Points, without any perceivable breadth. So that such Observations can here do us no good.

A way of making a probable guess at the distance of the Stars

When I saw this would not succeed, I studied by what way I could so lessen the Diameter of the Sun, as to make it not appear larger than the Dog, or any, other of the chief stars. To this purpose I clos’d one end of my twelve-foot Tube with a very thin Plate, in the middle of which I made a hole not [153] exceeding the twelfth part of a Line, that is the hundred and forty fourth part of an Inch. That end I turn’d to the Sun, placing my Eye at the other, and I could see so much of the Sun as was in Diameter about the 182d part of the whole. But still that little piece of him was brighter much than the Dog-Star is in the clearest night. I saw that this would not do, but that I must lessen the Diameter of the Sun a great deal more. I made then such another hole in a Plate, and against it I plac’d a little round Glass that I had made use of in my Microscopes, of much about the same Diameter with the former hole. Then looking again towards the Sun (taking care that no Light might come near my eye to hinder my Observation) I found it appear’d of much the same Clearness with Sirius. But casting up my account, according to the Rules of Dioptricks, I found his Diameter now was but 1/152 part of that hundred and eighty second part of his whole Diameter that I saw through the former hole. Multiplying 1/152 and 1/182 into [154] one another, the Product I found to be 1/27664. The Sun therefore being contracted into such a compass, or being removed so far from us (for it’s the same thing) as to make his Diameter but the 27664 part of that we every day see, will send us still the same Light as the Dog-star now doth. And his distance then from us will be to his present distance undoubtedly as 27664 is to 1; and his Diameter little above four thirds, 4"'. Seeing then Sirius is supposed equal to the Sun, it follows that his Diameter is likewise 4"', and that his distance to the distance of the Sun from us is as 27664 to 1. And what an incredible distance that is, will appear by the same way of reasoning that we used in measuring that of the Sun. For if 25 years are required for a Bullet out of a Cannon, with its utmost Swiftness, to travel from the Sun to us; then by multiplying the number 27664 into 25, we shall find that such a Bullet would spend almost seven hundred thousand years in its Journey between us and the nearest of the fix’d [155] Stars. And yet when in a clear night we look upon them, we cannot think them above some few miles over our heads. What I have here enquir’d into, is concerning the nearest of them, And what a prodigious number must there be besides of those which are, placed so deep, in the vast spaces of Heaven, as to be as remote from there as there are from the Sun! For if with our bare Eye we can observe above a thousand, and with a Telescope can discover ten or twenty times as many; what bounds of number must we set to those which are out of the reach even of these Assistances! especially if we confider the infinite Power of God. Really, when I have bin reflecting thus with my self, methoughts all our Arithmetick was nothing, and we are vers’d but in the very Rudiments of Numbers, in comparison of this great Sum. For this requires an immense Treasury, not of twenty or thirty Figures only, in our decuple Progression, but of as many as there are Grains of Sand upon the shore. And yet who can say, that [156] even this number exceeds that of the Fixt Stars? Some of the Antients, and Jordanus Brunus carry’d it further, in declaring the Number infinite: he would perswade us that he has prov’d it by many Arguments, tho in my opinion they are none of them conclusive. Not that I think the contrary can ever be made out. Indeed it seems to me certain, that the Universe is infinitely extended; but what God has bin pleas’d to place beyond the Region of the Stars, is as much above our Knowlege, as it is our Habitation.

Or what if beyond such a determinate space he has left an infinite Vacuum; to show, how inconsiderable all that he has made is, to what his Power could, had he so pleas’d, have produc’d? But I am falling, before I am aware, into that intricate Dispute of Infinity: Therefore I shall wave this, and not, as soon as I am free of one, take upon me another difficult Task. All that I shall do more is to add somewhat of my opinion concerning the World, as it is a place for the reception of the Suns or fix’d Stars, [157] every one of which, I have show’d may have their Planetary Systems about them.

Every Sun has a Vortex round it, very different from those of Cartes

I am of opinion then that every Sun is surrounded with a Whirl-pool or Vortex of Matter in a very swift Motion; tho not in the least like Cartes’s either in their bulk, or manner of Motion. For Cartes makes his so large, as everyone of them to touch all the others round them, in a flat Surface, just as you have seen the Bladders that Boys blow up in Soap-suds do: and would have the whole Vortex to move round the same way. But the Angles of every Vortex will be no small hindrance to such a Motion. Then the whole matter moving round at once, upon the Axis as it were of a Cylinder, did not a little puzzle him in giving Reasons for the Roundness of the Sun: which however they may satisfy some People that do not consider them, really prove nothing of the matter. In this æthereal matter the Planets float, and are carry’d round by its motion: and the thing that keeps them in their own Orbs is, that they [158] themselves, and the matter in which they swim. equally strive to fly out from the Center of this Motion. Against all which there are many Astronomical Objections, some of which I touch’d upon in my Essay of the Causes of Gravity. Where I gave another account of the Planets not deserting their own Orbs; which is their Gravitation towards the Sun. I show’d there the Causes of that Gravitation, and cannot but wonder that Cartes, the first man that ever began to talk reasonably of that matter, should never meddle with, or light on it. Plutarch in his Book of the Moon above mentioned says, that some of the Antients were of opinion, that the reason of the Moon’s keeping her Orbit was, that the force of her Circular Motion was exactly equal to her Gravity, the one of which pull’d her to, as much as the Other forc’d her off from the Centre. And in our Age Alphonsus Borellus, who was of this same opinion in the other Planets as well as the Moon, makes the Gravitation of the primary Planets to be towards the Sun, as that of the secondary is towards the Planets round which they move: Which Mr. Isaac Newton has more fully explained, with a great deal of pains and subtilty; and how from that cause proceeds the Ellipticity of the Orbs of the Planets, found out by Kepler. According to my Notion of the Gra[159]vitation of the Planets to the Sun, the matter of his Vortex must not all move the same way, but after such a manner as to have its parts carry’d different ways on all sides. And yet there is no fear of its being destroy’d by such an irregular motion, because the æther round it, which is at rest, keeps the parts of it from flying out. With the help of such a Vortex as this I have pretended in that Essay to explain the Gravity of Bodies on this Earth, and all the effects of it. And I suppose there may be the same cause as well of the Gravitation of the Planers, and of our Earth among the rest, towards the Sun, as of their Roundness: a thing so very hard to give an account of in Cartes’s System.

I must differ from him too in the bigness of the Vortices, for I cannot allow them to be so large as he would make them. I would have them dispers’d all about the immense space, like so many little Whirl-pools of Water, that one makes by the stirring of a stick in any large Pond or River, a great way distant from one another. And as their motions do not all intermix or communicate with one another; so in my opinion must the Vortices of Stars be plac’d as not to hinder one anothers free Circumrotations.

So that we may be secure, and never fear that they will swallow up or destroy one another; for that was a mere fancy of Car[160]tes’s; when he was showing how a fix’d Star or Sun might be turn’d into a Planet. And ’tis plain, that when he writ it, he had no thoughts of the immense distance of the Stars from one another; particularly, by this one thing, that he would have a Comet as soon as ever it comes into our Vortex, to be seen by us. Which is as absurd as can be. For how could a Star, which gives us such a vast Light only from the Reflection of the Beams of the Sun, as he himself owns they do; how I say could that be so plainly seen at a distance ten thousand times larger than the Diameter of the Earth’s Orbit? He could not but know that all round the Sun there is a vast Extensum; so vast, that in Copernicus’s System the magnus Orbis is counted but a point in comparison with it. But indeed all the whole story of Comets and Planets, and the Production of the World, is founded upon such poor and trifling grounds, that I have often wonder’d how an ingenious man could spend all that pains in making such fancies hang together. For my part, I shall be very well contented, and shall count I have done a great matter, if I can but come to any knowlege of the nature of things, as they now are, never troubling my head about their beginning, or how they were made, knowing that to be out of the reach of human Knowlege, or even Conjecture.