AN ESSAY Concerning a VACUUM. Wherein Is endeavoured to be demonstrated, that a vacuum Interspersum runs through the World, and is more or less in all Bodies. By a Lover of the Corpuscular Philosophy. London, Printed for Andrew Bell at the Cross-keys and Bible in Cornhill, near Stock-market. 1697. RENOVATE ANIMOS Earl of 〈◊〉 THE PREFACE TO THE READER, By another Hand. THE Doctrine of a Vacuum interspersed more or less in all B●●●es, (which is the Subject of the ensuing Essay) hath been generally looked upon as a Paradox in Nature, and fit to be exploded the Schools, than refuted by Argument. For the Authority of Aristotle, Cartesius, and such great Names, hath so swayed the Affections of many; that not allowing themselves that Philosophic Freedom, which is their Natural Right, they have insensibly enslaved their Reason, the freest and noblest Faculty of the Soul of Man, to those Magisterial Dictator's. And yet 'tis well known to such, as are versed in the Old and New Philosophy, that though the Assertion of a Vacuum hath not gained so many Proselytes as the contrary Opinion, there have yet been some, both in former Ages and in this, who with great Evidence of Reason have defended it. Epicurus, however mistaken in his Idea of Atoms, and their fortuitous Coalition into the Curious and Exquisite Frame of the Macrocosm; yet proceeded upon a Principle, neither Precarious nor Improbable, in the maintaining of a Vacuum: for this was the great Topick he argued from, 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉, etc. If there be such a Thing as Motion in the World, (and he must contradict the Sense of Mankind that denies it) there must of necessity be a Vacuum. Which Argument carried so much Strength with it, in the Judgement of that contemned, yet acute Philosopher, Lucretius, that he labours to instil it into the Minds of all his Readers, in these excellent Lines, Lib. 1. de Rerum Naturâ; Aut igitur motu privandum est Corpora quaeque; Aut esse admistum dicendum est rebus inane; Unde initium primum capiat res quaeque movendi. Translated thus by J. Evelyn. Then either we to Bodies must allow No Motion, or mixed Vacuum avow, Scattered through all the Parts; from whence each Thing Doth its first Principle of Motion bring. I know 'twill be objected against Lucretius, as it hath been formerly; That he is not to be regarded, because he was an Atheistical and Profane Author. But if this be sufficient to reject his sound Reasoning in other Matters, where Truth lies on his side; let the Objectors tell me, what Heathen Philosopher had not his Noevi in some Points or other, as well as Lucretius? I writ not this to vindicate Lucretius where he erred, but to show, that if the Exception be of force in the present Case against him; it must be admitted in others also against many more; yea, I presume, against all. To give a few Instances; Zeno tied God to a Series of Second Causes, inevitably liable to the Decrees of Fatality. Plato was for levelling all in his Commonwealth, and for the promiscuous use of the Nuptial Bed. Aristotle held the Eternity of the World, both a Parte ante, & a Parte post. And Cartesius himself maintained as great an Error, in asserting an Indefinite World. It was an excellent Saying of Augustine, In arundine sterili atque aridâ, De Bapt. contra Donat. l. 6. c. 1. etc. A Grape may sometimes hang upon a dry and fruitless Stalk. And, Truth is Truth (saith another) wherever I find it. If Peter, if the Sibyls, if the Devils shall say, King 's Lect. 40. upon Jonah. that Christ is the Son of the Living God, it is not in one a Truth, and a Lie in the other. Of later Years Gassendus, Charlton, Ward, and divers others have held a Vacuum; and though their Number has been few in Comparison of the contrary minded; yet the Weight of their Arguments is heavy enough to preponderate with the unbiass'd, and to turn the Scales against their Opposites. What the Ingenious Essayer hath performed in this little Tract, towards a Demonstration of a Vacuum; the sober and unprejudiced Reader may best inform himself, by a fair Perusal and impartial Examination. However, this, I think, I may modestly say, That as the Discourse itself appears to have been the Issue of a Ripe and Pregnant Thought; so it stood in no need of such a Preliminary as this, to usher it into the World. An ESSAY concerning a VACUUM. EVer since I read Gassendus, with some other late Improvers of the ancient Corpuscular Physiology, I could never subscribe the Doctrine of Absolute Plenitude among Bodies: and I am of Opinion, that the Arguments and Experiments, that have been of late Years employed in this matter; amount to a Demonstration, that there can be no such thing. For from such a Plenitude of Matter as is contended for, both by the Peripatetics and Cartesians, it will follow, that all Bodies are of equal Weight and Density, and every one of such an absolute Closeness of Parts, as not to admit the least imaginable Vacuity: which will go near to make all Bodies alike; it being the various Modification of Parts, with the different degrees of Rarity and Density, that makes all the Difference amongst Bodies. But now, if all Matter be crowded together, almost infinitely closer than any Marblestone, there can be no different Modification, no Motion, no Distinction amongst Bodies at all. This turns the Creation into a Chaos, Paradise into thick Darkness, and a beautiful World into a Monster. Mr. boil, the greatest Patron of Mechanical Philosophy, that was (perhaps) in the World, throughout all his Pneumatick Experiments; is every where so modest and so cautious, that he does not assert a Vacuum, even where one would think he has reason enough to do it: but at the same time it is easy to observe, that his Judgement, and the main Stress of his Argumentation lies entirely that way; and in some of his later Writings he is more positive, as I shall note presently. But Bishop Ward is very bold; for in his incomparable Letter to Bishop Wilkins, in which he examines Mr. Hobbs his Principles, he says, he doubts not but in the Age to come, the Motion of the Earth and a Vacuum will be acknowledged equally with the Circulation of the Blood, and be looked upon as absurd to deny any of the three. His words are these, Nullus ego dubito, quin seculo sequenti aequè fore portentosum, si quis vel Circulationem Sanguinis, vel Motum Terrae, vel Vacuum negaverit. But I would not willingly engage myself in a Logomachia, or Strife of Words, as sometimes happens, when there is an Agreement in the Thing. I shall therefore first endeavour to clear the Terms from Ambiguity, and show what kind of Vacuum I contend for, and what sort of Plenitude I deny: for both Vacuum and Plenum may admit of a Distinction. Dr. Charleton, who follows Gassendus at the Heels, distinguishes a Vacuum into disseminatum and coacervatum; Others use the Terms interspersum and continuum, etc. And then it will follow, that Plenitude also must admit of some such like Distinction: for it may either be considered as absolute, universal and every where alike, or else such as the various Texture of Bodies will allow, which must be different, according to the different degrees of Rarity and Density. Now this latter may be called Plenitudo laxa, and the former Plenitudo perfecta; the one will allow of a Vacuum interspersum, and the other of no Vacuum at all. Upon the account of this lose and open Plenitude (perhaps) it has been, that the Notion of all Places being full, has obtained so much in the World, and that almost every one can say, Non datur Vacuum; which in a qualified sense is very true, because there is no Place to be found, in which there is not Air, or something else. For there is no Chasm, nor wide gaping Distance among Bodies; since Gravity, which is essential to Matter, keeps all things together, and contiguous one to another, as close as their respective Natures will allow: For the Air itself is heavy, whatever hath been said to the contrary, and even the purest Ether would press downward, if there were not grosser Matter below: but the heaviest Substance always sinking, makes the lighter ascend. So that universal Gravitation suffers no empty Corners any where in the World, no Hiatus among the Parts of Matter; but all Space determinate or perceptible is supplied with Body, or Matter of one sort or another: supplied, I say, but not strictly and absolutely filled; though in a larger sense all Places may be said to be so full, that there cannot be a Vacuum coacervatum: as for Example; When we see a Vessel filled with Grains of Wheat till it can hold no more, we do not scruple to say, that Vessel is full of Wheat, though there are many thousands of empty Spaces, which the Grains of Wheat cannot fill. The like may be said of all other Bodies consisting of variously figured Particles, which can never adequately fill any Space whatsoever; tho the closer such Particles are conjoined, and the more exactly fitted one to another, the nearer they do approach to a Plenitude; but an absolute Plenitude is impossible, which is the thing to be proved. And by this time the Reader may apprehend what I aim at. In the next place than I advance this Negative Proposition, namely, That all Places are not equally full. As for Instance; Let us suppose two Vessels filled, the one with Water, and the other with Quicksilver; the Plenists will have them both to be full, and that in the utmost strictness of Speech: and I affirm they are neither of them so; for though they are both filled up to the Brim, yet both the Water and Quicksilver are porous Bodies, and the one much more than the other, there being a vast difference in Weight and Substance. And if a thousand Particles of the one lie within the Compass of an hundred in the other, than that hundred must be further distant: and there will ever be more or less intermediate Space, according to the Openness, or Closeness of Parts. So that unless we can find a Medium to fill those intermediate Spaces, it cannot be denied, but they must remain empty. But in Answer to this, that which is usually said in the first place, is, That Air fills all these intermediate Spaces, and leaves no Place empty. To which I reply, 'Tis impossible, that so thin and open a Body as Air should fill any Place whatsoever; because itself wants filling, and it cannot give that which it has not; it cannot furnish out another Body to an absolute Plenitude, which it is further from having, than that Body it is to fill; as if one should think to fill the Cavities of Water or Quicksilver with Sponge, or with a Honeycomb; for Air is a far more lax and open Body than either of these: so that we shall want another Medium to fill the Cavities of this; and when we have it, we shall yet want a third to fill the Pores of that, and so infinitely. In short, unless we can find a Medium, that has in itself no Pores, to fill the Cavities of other Bodies, those Cavities must still remain empty; for there cannot be an Absolute Plenitude, where any Spaces are not filled; and they can never be entirely filled, but by such a Medium as has in itself no Pores nor Cavities at all; and so must be more close and solid than the purest Gold, or any Substance that we know of in the World. But here again we are put off with Materia subtilis, which is (it seems) a certain Ethereal Substance, that penetrates and pervades the minutest and inmost Cavities of all Bodies, and adapting itself to the Figure of every Poor, adequately fills them all. To which I answer, That this Ethereal Substance is really nothing else but a purer sort of Air: So that what has been said of gross and common Air is likewise true of this, and so much the more, as it is dilated to a greater Extension. Who would attempt to fill the Cavities of Cork with a Net spread out to the greatest Extent? And if a quantity of Wool or Flax, being well thrust together, does admit of many thousands of empty Spaces, how much more when the same is expanded to far greater Bounds? So that if the gross and thick Air, which we breathe in, by reason of its Tenuity, cannot furnish out other Bodies to an absolute Plenitude; how much less the pure Ether, which in the superior Regions is millions of times more tenuious; and the higher you ascend, the Rarefaction still increases without Stop or Limitation. However, let us suppose for once, that this Materia subtilis is something distant both from Air and Ether, and that it runs through the Crannies and Vacuities of all Substance: this same Matter must consist of certain Particles or Atoms, and these must have some sort of Shape or Figure, either Globular, Cubical, Cylindrical, Tapering, or the like; that is, they must either be regular Particles, or else irregular; or at least a Mixture of both. Now it is impossible that ever these should lie so close, as to exclude Vacuity. One might as well suppose with Epicurus, that such Primordia rerum should, by their various Shuffles and Rencounters, jump into a World at first; as that ever afterwards they should put themselves into a Posture of absolute Plenitude. Cubes indeed of all other Figures are the fittest to lie close, and to exclude Vacancies: but then, as they are the least apt for Motion, so the Cavities they are to fill must either be exactly Cubical, and withal of equal Dimensions with the Cubes that are to fill them, or there will still remain certain Interstitia. But the Veins and Hollows that are in all Bodies, such as Wood, Stone, Metals, etc. are not pretended to be regular, and therefore the finest Particles of Matter, of whatsoever Figure, can never exactly fill them. It may perhaps be here objected, That our common Air, and these Ethereal Particles are so mixed and adapted each to other, as to compose a Medium fit to replenish all Space, and effectually to prevent a Vacuum. But this is no more than what might be said of Air mixed with Vapour, or any other thin and fluid Medium whatsoever: and the same Answer serves for all, unless they can find a Medium without Pores. For whether it be simple or compounded, the Argument will centre here, and come at last to this Issue; That either the Medium is porous, or it is not: if it be, it cannot fill the Pores of other Bodies, as hath been said; there cannot be more in the Effect than in the Cause, and that which has no Plenitude cannot give it. But if the Medium be not porous at all, what then? Why then truly, as soon as that is demonstrated, we must take new Measures; but in the mean time I think we can demonstrate the quite contrary. I remember not long ago, in discourse with a Gentleman of good Learning, and a great Cartesian, I brought the Matter to this same Test: he urged his Materia subtilis, or Ethereal Substance (for he made no difference) as Nature's Universal Agent to prevent a Vacuum. I demanded whether it was a porous Substance or not; he answered, No, it was entirely close without any Pores at all. Why then, said I, it is more solid than the purest Gold; he agreed, and said it was so; and there we left it, being both very well pleased: he thought he had gained his Point, and I was content to yield upon such honourable Terms. The truth is, as there is no way to prevent a Vacuum, but by such a fluid Medium as has no Pores, and so far the Gentleman was in the right: So on the other hand, such a Medium is impossible, it is against plain Matter of Fact, and the greatest Chimaera in the World. First, it is impossible that variously figured Particles should touch one another in so many Points, as to leave no empty Spaces: and especially if this Ethereal Matter consist of Globuli (as some talk) for these can touch one another (says Euclid) in one Point only, and so all the rest will be empty Space. And, secondly, it is contrary to Matter of Fact and common Experience: for the solidest things are always heaviest, and if Ether be such, it will press down to the lowest parts, and lighter things will mount above it. Gold would then be obliged to swim, which it never did yet; and we ourselves and every lose thing upon the Earth would be carried up into the superior Regions, and float above like Chips in Water, or Pebbles in Quicksilver. Such Extravagancies are the natural Consequences of supposing Ethereal Matter without Pores: it confounds the Nature of Things, and turns the World up-side down in a literal sense. But on the contrary, we have it from good Authority, that the Solidity of Gold and common Air differ in Proportion as 16150 to one. And the Learned Mr. Bentley (according to the Experiments of Mr. boil and Mr. Newton) scruples not to aver, that the ordinary Air in which we live, is of so thin a Composition, that for one part of its Dimensions which is material and real Substance, there are 16149 Parts, or more, mere Emptiness and Nothing. And the higher you ascend, where it is less compressed by the superior Air, the Rarefaction still increases: So that at the height of some few Miles from the Earth, it is computed to have a Million Parts of empty Space, for one of real Substance. But then at the height of one Terrestrial Semidiameter, it is of that wonderful Tenuity, that if a Sphere of common Air, of one Inch Diameter, should be expanded to the thinness of that Ether, it would more than take up the vast Orb of Saturn. See here the unaccountable Solidity of pure Ether, and how wild a Fancy it must be to think it without Pores or empty Spaces! In a word, he that denies a Vacuum obliges himself to reject at once the whole Corpuscular Philosophy, and must make the best he can of the Peripatetic Jargon. If therefore the Cartesians do allow that all Bodies are composed of Atoms, Cubical, Spherical, Conical, Cylindrical, etc. and at the same time contend for Absolute Plenitude; they couple two Notions together which naturally destroy one another. As if one should imagine that a Vessel filled with Dice and small Shot, together with contorted Cones, twisted Wires and Worms, winding Helixes, spiral and turbinated Springs, besides an infinite Variety of irregular Figures; and that all these should be promiscuously blended, or artificially laid together, without intermediate empty Spaces. Hitherto I have argued the Necessity of a Vacuum from the different Texture of Natural Bodies, and from the various Figures of their component Particles. Let us now consider more particularly, yet briefly, the business of Rarity and Density, and see how they stand affected in this matter, and what Account the differing Parties give of their Causes: And first let us here a Learned French Author in these words. Initium sumo à Densitate & Raritate, tantas difficultates Cartesii & Aristotelis sequacibus parientibus: Et statuo Corpus unum alio rarius esse, cum majore Vacuorum dispersorum numero, aut iis grandioribus, praeditum est; sic aër aquâ rarior, aqua è contra aëre densior: quia aër plura & majora obtinet vacua quàm aqua; & haec aëre crassior est: quia pauciora, minoraque possidet. I begin with Rarity and Density, which do so greatly perplex the Followers of Cartesius and Aristotle. And I judge one Body is more rare than another, when it hath either more or greater interspersed Vacuums. Thus Air is thinner than Water, because its Vacuums are more numerous and large than those of Water. And Water is thicker than Air, because it hath fewer and less Vacuums than Air. This is an easy and natural Solution: it puts no Shame upon our Faculties, being so very clear and intelligible. Let us now see what Account the two contending Parties give of this Matter. And first that of the Aristotelians is this: Raritatem & Densitatem dicunt esse qualitates, vel formas accidentales, ex potentia Materiae eductas. That Rarity and Density are Qualities, or Accidental Forms, educed out of the Power of Matter. If this be good Sense (of which I greatly doubt) it is as much as to say, that Rarity and Density are we neither know what, nor how they come to pass. Secondly then, let us hear the Cartesians, who say, Multò plus dari Materiae subtilis in Corporibus raris, quàm in crassioribus & condensatis. That Rare Bodies have much more Subtle Matter, than those which are more Gross and Dense. This indeed is not only intelligible, but very true: for I do not doubt but there is more Air or thin Substance (call it what you please) within the Cavities of Cork, than in the Pores of Lead. But this does not solve the Difficulty, unless it could be proved that a rarefied Body, together with the Materia subtilis therein comprehended, had equal Closeness of Parts with a Body more condensed, of which the quite contrary (I think) is demonstrable: for the more pure and subtle that any Body is, the less capable it is of filling a Place; and that which has empty Spaces of its own, can never fill the Cavities of another Body, as hath been said. But let us hear what Account our Modern French Author, St. Romain, gives of this Matter. Cur haec materia subtilior, & delicatior sit omni aliâ materiâ, quum omnis materia aequaliter crassa est & solida? Verum materiam hanc, inquiunt esse summè rarefactam; Nihilominus tamen eadem semper manet difficultas; nempe, unde magis rarefacta sit? Dicent id ex eo oriri, quòd partes non adeo sunt compressae. Itaque magis ab invicem distabunt; quocirca dantur vacua & intervalla: Nisi enim illa dentur, aequè compressae sunt ac in materia condensata: Sed si aequè sint compressae, non magis etiam ab invicem sunt remotae: Et si denique non magis ab invicem sint remotae, non sunt amplius rarefactae, & haec tandem materia subtilis non minus crassa erit ac quaelibet alia. Why is this Matter more fine and subtle than all other Matter, seeing all Matter is equally dense and solid? But this Matter, say they, is exceedingly Rarefied: Nevertheless the Difficulty is still the same, viz. how comes it to be more Rarefied? They will tell us, it proceeds from the Non-compression of the Parts; but then their Distance will be the greater, and so they grant there are Vacuums and Intervals: For unless these are granted, the Parts are as much compressed as in condensed Matter. But if they are as much compressed, they are not more remote from one another; and if they are not more remote from one another, they are not more Rarefied; and so this subtle Matter will prove as dense as any other Matter. Thus far the Learned Frenchman, of which the Sum is this; No Rarefaction without distance of Parts, no distance of Parts without Interval, no Interval without a Vacuum. And whereas the Materia subtilis is supposed to fill all, it is the least of all capable, as being the most Rarefied; so that there can be no Rarefaction without a Vacuum. Hither may be referred two Instances, the one of Rarefaction, and the other of Condensation, both which do strongly plead for a Vacuum; namely, the Torricellian Experiment, and that of a Windgun. As for the Torricellian Experiment, it is so well known at this day, being the same with the Weather-Glasses now in use, that I need not describe it. This is certain, that the Mercury subsiding, the upper part of the Tube is deserted, and not so much Substance left remaining, as to oppose the Mercury in its return back to the upper end, in case the Tube be inclined to a side. However, it is not pretended that the said upper part of the Tube is quite empty: for whilst the Mercury is a pouring in at first, some small Bubbles will still escape together with it; and when the Tube is inverted, and the Mercury sunk down, those Bubbles of Air will extend their Springs and enlarge, endeavouring (as it were) to fill the empty Part with a sort of Air rarefied and expanded far beyond the natural Texture of common Air, and consequently the Particles must be more remote from each other, and the intermediate Spaces larger. Thus the several Turns of a Watch-Spring are at greater distance one from another, when at liberty, and Force removed, than when the same is compressed or wound up together. As for the Vacuum Boyleanum, it is, in the nature of it, the same thing, but improved to a greater height, and illustrated by many curious Experiments. The Vessel is of great Capacity, containing above 30 Gallons; and when the Air is exhausted, Animals cannot live in it, nor Infects fly, nor Caterpillars crawl, nor Flame burn, nor Syringes draw up Water, nor Fire run along a Train of dried Gunpowder. These are lively Demonstrations of an extremely rarefied Medium, that the Parts of Matter are thin scattered, and that therefore, as the French Author says, there must be Vacua & Intervalla. The Windgun is a curious Invention, but a dangerous Tool in the Hands of an ill-disposed Person, since it does prodigious Execution with very small Noise. Bishop Burnet in his Letters of Travel, tells of a Smith at Basil, who had so far improved the Invention, that he could make one to shoot ten times with once charging, and yet, having a mind to give a home Blow, one might discharge the whole Force at once. I never saw any but one, which was about the size of an ordinary Fowling-piece, having a double Barrel of Brass, one lying within another, being close at the Muzzle, and a Space reserved between the Convexity of the one Barrel and the Concavity of the other. It had in the Stock or Breech an Air-Pump, which was to convey Air into that Cavity or Space between the two Barrels, and to keep it there as long as one pleased. It was discharged by a Tricker like another Gun, and had an incredible Force. By working at the Pump the Gun was charged, and it took a great Strength, especially after a certain time, when the Air in the Cavity began to grow stiff and would not easily admit of any more. Now it is said that Air may in this manner be compressed till it be sixty times the thickness and consistence of common Air; but if less, it is sufficient for what I design, namely, that Air thus condensed, has less Vacuity than common Air, and therefore common Air must have more than it, and pure Ether most of all. Whatever is capable of Compression must include Vacuity: for either there must be room for the Particles of Matter to retire into, when they are forced together, or else they must be crowded one into another, which is Penetration of Dimensions. And if they tell me a thousand times that Materia subtilis fills all, I return as oft, Nil dat quod non habet. It may indeed run through all other Bodies, but it can never fill them, because it is not full itself: and that which is so greatly rarefied can never thicken or condense any other Substance to an Absolute Plenitude. Having endeavoured to show, that an Absolute Plenitude is inconsistent with the Mechanical Affections of Matter; I am now to consider how Motion can be performed without a Vacuum. It was Gassendus his great Principle, No Vacuum, no Motion: and it is the general Sense of Mankind, that a Body cannot stir without room, and that Room to move in nothing else but a Vacuum. If I were placed in the middle of a Marble Stone, I should make but small haste to get out: and yet Marble is not by far so close, as the World must be supposed to be without a Vacuum. Suppose some Place were filled with Dice, or Cubical Bodies set close and in order: how should those that lie under be capable of moving, unless room be made by removing others? And how should others be removed that are as fast locked up as they, and all beset and surrounded still with other Cubes, to the utmost Extent, and no empty Space any where? To which if it be replied, that this indeed is true in the case of hard and solid Bodies, but not where there is a soft and yielding Medium, such as Air, which gives a free and easy Passage to any kind of Motion; I would only demand what it is that makes the Medium so easy and yielding? For Omnis materia aequaliter crassa est & solida. The Atoms of Air are as solid as those of Steel, and it is only Vacuity that makes Softness. We see that the larger and more numerous the Pores and Vacancies of any Substance are, as in Wool, Sponge, and the like, the more soft and yielding are such Bodies. But let us for once suppose (how absurd soever it be) that this same Medium that we breathe in, is an absolute Plenum, and withal, that a Body may be capable of moving therein: the Consequence will be one of these two: Either that such Motion will be continued to the utmost Bounds and Selvedg of the World, or else there will be Penetration of Dimensions. Let but a Fly stir a Wing or a Foot, it must beat back the Air, and that Air must either move the contiguous Particles, or else be thrust into them, there being no empty Room to get into, but all solid Substance. So that if you will not allow two Bodies in one Place, you must be forced to grant that a Motion once begun must move the adjoining Parts of the Medium, and those again others contiguous unto them, and so successively to the furthest Extent of Matter; which if it be not infinite, the Motion at last must end in Vacuo; and if it be infinite, the Motion is endless. Choose now which you please, an Infinite World, or a Vacuum. It has been observed, that the discharge of great Guns has been heard above an hundred Miles, but without a Vacuum it would not stop at an hundred Millions. For in Absolute Plenitude a Motion once begun must continue, so long as there is contiguous Matter to be moved; and if Plenitude be infinite, Motion will be so too. On the contrary, in such a porous and springy Medium as we suppose the Air to be, how easily is this Matter solved! When Motion gins, it forces the Air that is next it, and that again the next, but still in a less and less degree till the Motion ceases: because there is not such a Continuity of Parts as to preserve the Motion any long time. For the Springs of Air have room to yield and give way: and when the bending Force is removed, they return again to their former State potentiâ sua restitutiuâ. Now the thinner that any Medium is, the fainter is any violent Motion made therein, and sooner at an end. Which is the reason that a Gun being shot off on the top of the Alps, or Pico Teneriff, sounds but like the breaking of a small Stick; but being discharged at the bottom of those Mountains, by reason of thicker Air and Repercussion, it roars like Canonshot, and continues for a considerable time. But in case of Absolute Plenitude, the shooting of a Burtree-Gun would be heard among the fixed Stars, and the Motion would be continued beyond the Primum Mobile, if such a thing there be, and never cease till Matter be no more, or till there be a Vacuum; which leads me to consider Des Cartes' finespun. Notion of the World's being indefinite. That famous Philosopher of France, finding that empty Space would not consist with his Principles, and yet considering that a bounded World would infer a Vacuum, if not within it, yet at least beyond it; he thinks to put us cunningly off with the Term Indefinite, which can import no more than this, that we do not know how far the World extends. But must our Ignorance in that Case be a Ground for him to impose upon us in another? Must we indeed own that the World is neither finite nor infinite? I beg his Pardon. I remember I have met with some, who would have persuaded me, that there are certain Questions, which cannot be truly answered neither in the Affirmative nor the Negative; as, Whether Quantity be divisible in infinitum? I grant there is great Difficulty on both sides, and so there is in a thousand other Cases and Questions: How else should there be so many Disputes and Controversies in the World? Truth is many times hard to find; but where there is a direct Contradiction, it must be on one side or the other. For as two contradictory Propositions cannot both be true: So the Affirmative and Negative of any one Proposition cannot both be false. He that says there is a Vacuum, and he that says there is none; as it is certain that both these do not speak Truth, so it is no less certain that one of them does. Let the Question then be put, Whether the World is infinite, or not? If this be true in the Affirmative, it is certainly false in the Negative, and è contra. What is neither finite nor infinite is a Chimaera, and this Indefiniteness of the World is a Shame, and no better than an Occult Quality. The Infiniteness of the World and its Eternity are both unfriendly to Religion: they seize the Divine Attributes for the use of the Creatures, and rob God of his Honour to bestow it upon Dust and Ashes. What more illustrious Characters can belong to the Divine Nature than to be Immense and Everlasting? The Learned Frenchman knew this well enough, which made him think upon a shift to save both his Hypothesis and Religion harmless. But it will not do the feat: for as the World had a Beginning, so it has its Bounds, and will have a Period. Heaven and Earth shall pass away, but the Word of God abideth. The Notion of a Deity comprehends all Perfection, but an infinite World is itself incomprehensible: and how two Infinites or two Incomprehensibles are consistent, is I think beyond Human Understanding. It remains therefore that the World is finite, and has its Boundaries; and then I demand what is beyond those Boundaries but Emptiness and Nothing? I come now to consider Gravitation, and to see how it affects the present Question. It is that which not only fills all Places, as close as the various Texture of Bodies will permit, as was said before; but in sundry Experiments it also discovers a Vacuum, and particularly by the rising of Water in a Pump to a certain height, and no further. Now it is but of late Years that the Gravitation of the Air has been spoken of: for in all the Reign of Aristotle we hear not one word of it, and to the famous Galileo it is, that we are indebted for this remarkable Discovery; which however it might be accidental, yet he was the first that observed the Matter of Fact, and assigned the true Cause of that very odd Phenomenon, contrary to a prevailing Maxim, Nil gravitat in suo Elemento. The Business was in a certain place to raise Water by a Pump; and this Learned Man (it seems) was present, whether as a Director or Spectator only, is not greatly material. But so it was, that the Pump being finished, and all things tight and well fixed, he observed that the Water ascended cleverly to the height of 35 Foot and somewhat more, but there it took a resty Fit, and would not stir an Inch further, let them ply the Pump never so hard. What (says he) is the Fuga Vacui quite run out of Breath? Does Nature's Abhorrence of a Vacuum extend to 35 Foot, and not to 36? This deserves to be considered. Now a Pump is a Philosophical and very instructive Engine, in which the Water (which is a heavy Body) ascends against Nature, and follows the Sucker for company. But what is it that makes the Water so complaisant? Why Nature (say the Peripatetics) has taken up a Resolution that she will not suffer a Vacuum: so that when the Sucker is drawn up, and the Air cannot get by to fill the place, Nature has laid her Commands upon the Water, and away she follows in all haste ob fugam Vacui. This Reason has long obtained. But why should Nature stop thus on a sudden? For, says Mr. boil, Nature will quietly enough permit a Vacuum rather than lift up the Water above the height of 35 Foot, which she is by no means able to perform, and of which the World was ignorant till the time of Galileo. So that, it seems, there is a certain Juncture of Time and Circumstances, in which Nature lays aside all her Spleen and Abhorrence of a Vacuum: and this very Experiment of a Pump, which for many Years, or rather Ages, has been urged as the strongest Argument against a Vacuum, is a plain Demonstration that there is one. The true Reason then of this Effect is Gravitation, or the incumbent Weight of Air, that raises the Water to a certain pitch, but is not able to raise it higher. For it is a Fallacy to think that the Water ascends by Attraction: it is Pulsion, or Force from below, that thrusts the Water upward, and not any Hooks or Ligatures by which the Sucker takes hold of the Air, or the Air of the Water; which may be thus further explained. First then, the common Air that we live in and have above our Heads, does press upon the whole Face of the Earth and Water with a certain Weight, which is, for the most part, every where equal and uniform, with allowance for the several Changes of Wether, according to which the Air is lighter or heavier, as is daily observed by the rising and falling of the Mercury in the Weather-Glasses. And then the higher you ascend, it is still the lighter, as was observed by the Learned Dr. Power, who tried the Torricellian Experiment both at the top and bottom of Hallifax-Hill in Yorkshire, and found a considerable difference. Secondly, A Pump is always supplied with Stagnant Water at the bottom, in a Well or Pit digged for that purpose. And being thus fixed and complete, you draw the Sucker, and this rarefies the Air below it, because that which is above cannot pass by the Sucker, and so get down. And then continuing still to draw, you rarefy the Air more and more, till at last it grows so thin, that it leaves room for the Water to ascend, which is forced upwards by the Pressure of the Air upon the Stagnant Water in the Pit below. And it will rise just so high till there be an equal Balance between the Pressure of the incumbent Air without, and the Weight of the Water within; of which the mean Proportion is 35 Foot, never reaching 36, nor ever so little as 34, but varies within that Compass according to the Temper of the Wether, as hath been said. And when it comes to an Equilibrium, Nature cares not one Farthing whether there be a Vacuum or no. It now only remains that I consider this Matter by the Rule of Staticks, or the different Weight of Bodies, as they preponderate one another in the Scales. For, according to the Doctrine of Absolute Plenitude, all Bodies should be of equal Weight, so that a Cubical Inch of Lead (for Example) should not outweigh a Cubical Inch of Cork: but this being against Experience, What Reason do the Plenists give for so great a difference? Why, they say, the difference of Specific Gravity proceeds from the various degrees of Rarity and Density. Well, we say the same. But from whence proceeds that Variety? They say, ex potentia Materiae, and we say, from more or less Vacuity, as hath been already discoursed. For that which makes the difference is nothing else but empty Pores and Cavities among the Parts of Matter: and hence it is that Cork is so much lighter than Lead. In like manner, all other Bodies differ in Weight, according to their proportion of Substance, or according as the Parts of Matter are more or less compacted, which is nothing else but different degrees of Emptiness, the closer Substance being the heavier; and the more of Cavity or Porousness there is in any Body, it is still the lighter, always supposing equal Dimensions. This being plain Matter of Fact, I suppose our Adversaries will not deny it: but then comes that wonderfully officious Materia subtilis, and fills all. This and the Indefiniteness of the World are two Philosophical Strains, devised on purpose to banter and outface a Meridian Truth: and it is unaccountable, that so fine a Wit as Des Cartes was, could not see the Shallowness of these Shifts, and the Necessity of admitting a Vacuum. Concerning this Ethereal Substance, or superfine Matter, I have said enough already, and have showed, that it is not capable of filling any Place whatsoever: I have now only this to add, that it must have Weight, as all other Matter has: it is not a Spiritual but a Corporeal Substance, and therefore must weigh proportionably to its Bulk. So that as much of it, as at any time is comprehended within the Cavities of Cork, or any other Substance, must gravitate jointly with that Substance: and therefore if the presence of that Ethereal Matter, or whatever it be that penetrates Bodies, made an absolute Fullness, than all Bodies of equal Dimensions would still be equally heavy; and so a square Inch of Cork, and another of Led laid in the Balance, would keep the Scales in Equilibrio. For whereas this Ethereal Substance is supposed by our Adversaries to fill all Cavities, and to make all Bodies equally full, it will follow that a Cube of Cork, together with its included Ether, must be as full of Matter as a Cube of Lead of the same Dimension; and consequently must have equal Solidity and Closeness of Parts, which will of necessity infer equal Weight upon the Scales; there being no reason in the World why two Bodies of equal Solidity and Compactness should not have the same Specific Gravity. But now if Led be twenty times heavier than Cork (which is the least) it must contain twenty times the Quantity of Matter, that is, twenty substantial Particles for one. And the Dimensions being equal, it must follow that in Lead, twenty Particles of Matter are contained in the same Space or Compass, for which there can be allowed but one Particle of the Cork, and so one has as much Room in this, as twenty in the other. So that the Business comes to this Issue, either a Vacuum or Penetration of Dimensions. For if one Particle have the Room of twenty, then either these twenty are thrust one into another, which is impossible, or else that one is placed at a distance from those about it. But if one Particle be placed at a distance from another, then is there empty Space between, that is, a Vacuum; quod erat demonstrandum. THE CONCLUSION. THere is one thing I forgot to mention in its proper place, and so I shall put it here for a Conclusion. The Cartesians are wont to urge their Notion of a Body against this of a Vacuum. Simple Extension, according to them, is that alone which constitutes Corporeity: so that whatsoever is extended in Length, Breadth and Thickness, must be a Body: and because a Vacuum may be supposed to have these Dimensions, they will not allow of any such thing. To this I answer: First; One may with equal, if not far greater Reason, object against their Notion, than they against a Vacuum, that being precarious and arbitrary, and this resting upon clear Evidence. And if I have demonstrated a Vacuum (as I think I have) then let their Notion of Simple Extension shift for itself. Who gave them Authority to impose upon the World a Notion, of which there is no Necessity, no Evidence? A Vacuum is necessary to give way to Motion, since a close Constipation of Parts throughout the Universe will never admit of it. And then it is evident there can be no degrees, no Variety of Rarity and Density without a Vacuum, since all must be equally dense and absolutely full, as hath been showed. And as it is necessary to allow a Vacuum within the World, so much more to admit one without or beyond it, otherwise Matter would be infinite; and if so, I know not why it may not as well be Eternal; and thus at last we shall make the World to be God himself, as some Theists are said to do. Now let the Plenists show as great Necessity, and as good Evidence for Simple Extension, as hath been, and may yet further be showed for a Vacuum, and it will deserve Consideration. Secondly; The ancient Corpuscular Philosophy, settling a distinct Notion of a Body, makes it to be a Substance impenetrably extended, which hath nothing belonging to it but Magnitude, Figure, Texture and Motion, as Dr. Cudworth shows with great Learning in his Intellectual System. Now this takes away all Confusion, and sets every thing in clear Light. For first, it casts off those unintelligible Forms and Qualities of the Aristotelians, which seem to be so many Spirits possessing (as it were) those Bodies to which they are said to belong it shows how far Body can go, and where Incorporeal Substance gins. Secondly, it distinguishes a Body from the Space that it possesseth, which Simple Extension does not: for any Room that a Body fills, is just as much extended as the Body that fills it, but is not the same thing. Thirdly, it distinguishes a Body from a Spirit, which is a Substance penetrable, according to Dr. More: For that Learned Man defines a Spirit to be a Substance penetrable and indiscerpible, and a Body discerpible and impenetrable; so that he makes Impenetrability essential to a Body, without taking notice of Extension. However, I doubt not, both he and others do allow Extension proper to a Body, but I deny it to be the adequate Notion of it, since it does not distinguish Body from Space: and he that will not allow of that Distinction, may say (if he pleases) that a Man differs not from the Chair he sits in, or the Room he takes up. And why must we subscribe to Des Cartes against the common Sense of Mankind? since it is well known that that Gentleman has admitted sundry things into his Philosophy, not because they are probable, but because they agree with his Hypothesis; witness the mere Mechanism and Insensibility of Brutes, which few believe, and most Men laugh at. But let him pass with all the Honour he has got: I grant he was a famous Wit, and so I leave him. And till I be better informed, which I am always willing to be, I apprehend the Matter thus, Spirit Substance penetrable unextended. Body Substance extended impenetrable. Space, or Vacuum penetrable extended no Substance. Thirdly; But because it may be wondered at by some, that a pure Nothing should have Extension; I make this Supposition, which indeed has been made by others, but the Inference arising thence I never yet saw answered by any. It cannot be denied but that God Almighty, who made all Things out of Nothing, can reduce again all Things into Nothing at his Pleasure, and can, if he should think it fit, annihilate the whole World, or any part thereof. Suppose then a Chamber, or any determinate Space, so many Yards (be it more or less) in Length, Breadth and Height; and that God by his Almighty Power should annihilate the Air within this Chamber, and make it a Space purely void, permitting the Walls to stand: I would inquire of any Man that is not under a violent Prejudice, whether this Chamber would not have the same Dimensions it had before? And would it not be all one, as to Length, Breadth and Deepness, whether it were filled with Lead or with Hay? or whether it had Air within it, or were quite empty? Now this being supposed, it is evident that a Vacuum may be extended, and consequently that Simple Extension is not the full and adequate Notion of a Body. And this may be sufficient for an Essay; in which I have set down my Thoughts, without design of Dogmatizing or Imposing. I writ for my own Instruction. And if any Man will rectify and improve what I have left rude and imperfect, he will much oblige me: if none will be so kind, I shall however obtain another End which I propose to myself, namely, innocent Diversion, and the Pleasure of Speculation. FINIS. BOOKS sold by Andrew Bell at the Cross-keys and Bible in Cornhill, near Stock-market. THE General History of England, both Ecclesiastical and Civil, from the earliest Accounts of Time, to the Reign of his present Majesty King William III. Taken from the most Ancient Records, Manuscripts, and Historians. Containing the Lives of the Kings, and Memorials of the most Eminent Persons both in Church and State. With the Foundations of the Noted Monasteries, and both the Universities. Vol. I. By James Tyrrel, Esq Fol. A New History of Ecclesiastical Writers: Containing an Account of the Authors of the several Books of the Old and New Testament; and the Lives and Writings of the Primitive Fathers; An Abridgement and Catalogue of all their Works, etc. To which is added, A Compendious History of the Councils, etc. Written in French by Lewis Ellies du Pin, Doctor of the Sorbon. In seven Volumes. Fol. A Detection of the Court and State of England during the Four last Reigns, and the Interregnum. Consisting of Private Memoirs, etc. with Observations and Reflections: And an Appendix, discovering the present State of the Nation. Wherein are many Secrets never before made public; as also, a more impartial Account of the Civil Wars in England, than has yet been given. By Rog. Coke, Esq The third Edition much corrected, with an Alphabetical Table.