An entire body of philosophy according to the principles of the famous Renate Des Cartes in three books, (I) the institution ... (II) the history of nature ... (III) a dissertation of the want of sense and knowledge in brute animals ... / written originally in Latin by the learned Anthony Le Grand ; now carefully translated from the last corrections, alterations, and large additions of the author, never yet published ... by Richard Blome.

The First Part OF THE HISTORY OF NATURE. OF BODIES. (Book 1)

CHAP. I. Of a Body Extended.

I. The Exi∣stence of Bodies is evident to our Senses. THO' our Senses are often mistaken, and being deluded by false Repre∣sentations, do circumvent our Mind; yet have we no safer way by which we may arrive to the Knowledge of Corporeal things, than when with their assistance we measure their Dimensions, and by Signs conveyed through our Eyes, discover their Existence: For it is by their Advertisements we come to know, that Matter consists of 3 Dimensions; and that the Parts of it are capable of various motions, have different Forms, and do diversly affect the Organs of our Senses. For tho', it may be, what is pre∣sented to our Eye, be only such in outward Ap∣pearance, and be represented to us quite other∣wise than indeed it is; yet must not we therefore suppose it to be no more than a Phantasm, or some vanishing Appearance, and such as is not to be ranked in the Catalogue of Things; seeing it is necessary that something that is Bodily, must lye hid under that shell or outward Appearance, and which really is the basis and foundation of the Figure we see; tho' because of its distance, or for other Reasons, it may not be perceived such as indeed it is, but takes to it self another Appear∣ance, that it may arrive at the Organs of our Senses.

II. The Senses are not deceived, as to the Matter or Subject of things. There is no question, but that he to whom a Square Tower, viewed at a distance, appears to be Round, hath something that is Material or Sub¦stantial conveyed unto his Organ; since it is im∣possible that either a Square or Round Figure should be seen, without any thing to support it, or that might be the Subject of it; it being a plain Contradiction, that a Mode should be taken from Matter, and exist without it: For indeed if we well consider the Nature of a Mode, we shall find that it cannot so much as be in our Thought con∣ceiv'd as separated from it. For tho' we can have a clear perception of Substance, whether Material or Immaterial, without their Modes; yet by no means can we conceive those Modes, without the said Substances, since it is their very Nature to affect and diversifie Substances.

III. The Opinion of the Ancients about the Nature of a Body. Wherefore the Ancient Philosophers did demon∣strate, that a Body consists of a concurrence of Figure, Magnitude and Resistance; because they found nothing but Matter was extended in Length, Depth and Breadth; nor any other thing besides it, that could not abide its like in the same place with it, but pusheth it thence, and excludes Pene∣tration. For herein do Material Substances differ from Spiritual, because the former fall under our Senses, carry a bulk with them, and are subject to the Touch. By the word Touch, we do not only un∣derstand the Sense so called, which is peculiar to Animals, and whereby they feel External Bodies; but that more general, whereby 2 Bodies touch one another with their Surfaces, and whereby they are intimately close to one another. For it is the property of Material things only, to touch and be touched, and to be joyned together by a kind of middle Term; which is so evident, that it cannot be question'd by any that either make use of their Imagination, or perceive any thing by the Senses: As LUCRETIUS in his First Book tells us,

That Bodies are, we all from Sense receive, Whose Notice, if in this we disbelieve, On what can Reason fix, on what rely? What Rule the Truth of her Deductions try, In greater Secrets of Philosophy?

IV. How a Spirit is said to be extended. But some it may be will object here, that a Spirit also is Extended, and yet is is excluded from participating of the Nature of a Body. To which I Answer, That when a Spirit is said to be ex∣tended, this is not to be understood according to the threefold dimension of Bodies, which we ima∣gine; but with respect to its Power and Energy, whereby a Spirit diffuseth its active Force, some∣times through a larger, and at other times through a lesser part of the Bodily Substance; so that in case there was no Body or Space, a Spirit could

never be understood to be extended, that is, to have, or correspond with any dimensions.

V. Whether there be any Vacui∣t••••s in Bodies. The only difficulty that remains to be resolved, is, whether besides the Bodies, whose Nature, we have said, doth consist in Extension, there be any Vacuity in Nature, destitute of all▪Matter, which yet enjoys the properties of Longitude, Latitude and Profundity. GASSENDUS, who hath madc it his business to restore the Doctrin of EPI∣CURUS, and hath made himself Famous by raking these Emptinesses out of the Darkness, wherein they had for many Ages been buried, in his Animadversions upon the Tenth Book of LA∣ERTIUS, concerning EPICURUS his Phy∣siology, doth both by Reasons and Experiments endeavour to prove, that there are empty Spaces in the World; which tho' they do not actually contain any Body, yet are so dispersed amongst Bodies, as to be ready to admit Bodies and contain them. Much after the same manner, as a Vessel is said to be Empty, when it is destitute of any Li∣quor, which yet it is capable of receiving. For if this Liquor chance to be emptied out of the Vessel, the inward Surface of the Vessel, which before contained the Liquor, must needs remain empty; except some other foreign Matter come in to fill up its sides, and be commensurate to the Dimensions of the Body that fill'd it before. He confirms his Opinion by the Example of a Heap of Wheat, betwixt the grains whereof many little spaces intervene, which are not taken up by them, forasmuch as their Surfaces appear to the Eye, to be distant from each other, it being impossible they should lye so close together, but that they must leave some Intervals destitute of any Bodily Sub∣stance.

VI. A Physical, and a Ma∣thematical Body do not differ. But GASSENDUS doth not seem, in this his Assertion, to have warily enough consider'd the Nature of a Body, which doth not only con∣sist in a Physical or Natural, but also in a Mathe∣matical Extension; and which is of that intimacy to it, that it cannot so much as in Thought be separated from it. So that Extension is Recipro∣cal with a Body; and as there is no Body which doth not consist in Length, Breadth and Depth; so there is nothing commensurate to those 3 Dimensions, but hath also the Nature of a Body.

VII. The Di∣stance that is between Bodies, or the parts of a Body, do not prove a Vacuum. But some will say, We find little Spaces betwixt the particles of Bodies, which because of the di∣versity of their Sides cannot be filled up by them. I grant it; but will it follow from thence, that those Intervals or Spaces must therefore be Empty, or destitute of any Bodily matter? For why may they not be fill'd with Air, or some other Matter more subtil than it? For if the said Parts be distant from each other, and take up different places, how can they be conceived to be distant, or truly said to be so, by means of an Empty interval? Seeing that according to that Saying amongst Naturalists, Something must always intervene between those things that are distant. For, seeing that Distance, which cannot be found but between things more than one, is a kind of Relation; and that every such must have a Foun∣dation, it is necessary that the said Relation rest on a real ground or basis: Forasmuch as a Non-entity hath neither Affections nor Operations; and con∣sequently, that which is Nothing can never con∣stitute the Distance of Bodies.

VIII. Possible Re∣pletion is not suffici∣ent to con∣stitute Distance. Neither must we assert with some, that Distance is founded in the Bodies themselves, that are di∣stanc'd from each other, and that Possible Repletion is sufficient to constitute it. For from this Suppo∣sition we might lawfully infer, that they are at a Distance from one another, which way soever they are posited or disposed, seeing that the same Foun∣dations do still remain, whether they be distant, or touch one another. Wherefore Distance must be assigned to something that is different from the Bodies themselves; which seeing it cannot be Im∣material, for that it is unextended, we must have recourse to something Corporeal that must be the Cause of it.

IX. Extension is that which constitutes Material Substance. I know very well, that some Philosophers do not approve of our assigning triple Dimension to be a Substance; they looking upon it to be no more than a Mode, or Accident. For who doth not consider the Extension of a Stick, to be only a Mode of it, and that the Stick is the Subject or Substance which supports it? But it will be easie to shew, that this Error is only deriv'd from our common way of expressing our selves; and that it is every whit as absur'd to assert it, as if a Man, hearing some speak of the Royal Palace, should imagine these 2 words to mean 2 things, and that one of them was a Mode of the other, But to the end, that all the difficulty we meet with in this business may be cleared out of the way, we shall only take notice, that such is the Nature of a Substance, that it can exist without a Mode; whereas a Mode, on the contrary, doth so depend upon Substance, that it cannot exist without it. Now it is apparent, that the Extension in a Stick, can be without a Stick, seeing that there are many Bodies that have not the Form of a Stick, which notwithstanding have Extension; but there can be no Stick, which is not extended. And therefore it is so far from this, that Extension can be said to be the mode of a Stick; that we must rather conclude, that Exten∣sion deserves the Name of Substance, and that the Being of a Stick is only the Mode of it.

X. Nothing that is In∣divisible can be con∣ceived to be in a Body. Hence it is apparent how foolishly they Talk, who consider Mathematical Points in an Extended Substance, and will needs have the divisibility of it to be bounded by an indivisible Term or Boun∣dary. For if in any Line, by division we come to the last Indivisible; that being once taken away, if you divide the other Parts after the same manner, you will at last come to the like indivisible or un∣extended Terms; and afterwards having made a like division of all the rest, you will find nothing else in this extended Line, but Indivisible or Mathe∣matical Points: Which is not only contrary to Reason, but also destroys the Notion we frame of Extended Beings.

XI. An Objecti∣on of the Epicureans. But the Epicureans will Object, That the last Resolution of Natural Compounds, is into the least Natural Bodies or Atoms; for that otherwise every Body would be divisible into Infinite, which they suppose to be an Absurdity. For that every thing which is Divisible, can only be divided into those Parts, which are actually in it; and consequently, that if Bodies be infinitely divisible, they must have actually infinite Parts: And so all Bodies will be actually infinite in their Extension, which no Man in his Wits will undertake to assert.

[illustration]

[illustration]

Book. 2. Part. 1. Chap. 1

G▪ Freman▪ I••

I. Kip. Sculp▪

To the Right Reverend Father in God Thomas Lord Bishop of Rochester, Deane of Westminster &c.^a.

This Plate is humbly Dedicated by Richard Blome.

XII. A Physical Atom, or least Body, is divisible, because it consists of Parts. I intend to give a full Answer to this Objection, in the Fourth Chapter; but shall here demand of these Defenders of EPICURUS, whether an Atom, which they contend is Indivisible, have any parts; or whether it be destitute of all parts, and consequently of Extension? If they affirm the latter, then their Atom doth not differ from a Ma∣thematical Atom. If they affirm the former (for it cannot be denied, seeing that every Atom is endued with triple Dimension, and hath its parti∣cular Figure) it is obvious to enquire, whether the parts of an Atom consist of other less parts, and so on to Infinity; or whether at last we must come to the least parts, which admit of no further Di∣vision. If they maintain this, they embrace the Opinion of ZENO, and so will be bound to maintain and defend a Mathematical, and not a Physical Atom, which indeed is no better than a meer Fiction; but if they chuse rather to maintain the other, there is nothing in Bodies that is alto∣gether indivisible, nor any Atom, whether it be called Mathematical or Physical.

XIII. GOD can divide a Physical Atom. Besides, an Atom cannot be conceived to have a Figure, and several Angles really and in∣trinsecally different from each other; for if so, it could not be Indivisible, and consequently no Atom. For is it not evident, that all those things that can be conceived by different Idea's, and that have a real independent Existence, can also be divided and separated from each other? And cannot the Infinite Power of GOD, at least, do as much as our Finite Intellect can conceive? Now our Understanding can conceive 2 Angles of the same Atom under several Notions, and know one of them without knowing the other; and con∣ceives also that several Angles of the same Atom do subsist independently of each other; and there∣fore it is not to be question'd, but that GOD, by his Omnipotence, can separate these Angles from each other.

CHAP. II. The Arguments of EPICURUS Answer'd, whereby he endeavours to prove, That there are empty Spaces intersperst between Bodies.

I. The Rest, or Motion of Bodies, does not require an Empty space. EPICURUS, who confounds Place with a Vacuum or Empty Space, and supposeth that all Bodies have their residence in those Vacuities, is of Opinion, That except there were such, Bodies would have no places to exist or move in. For since a Place is commensurate to the thing placed, and the hollow Surface of that, must be equal to the outward Surface of this: As also, that Place is accounted Immoveable, and that it is repugnant for it to be removed from its position; it follows that Place must always continue the same, even after that the Body, which fill'd it before, is re∣moved elsewhere, and successively takes up other Places; and that therefore it is necessary, that the same be left Empty, and do preserve its Parts im∣moveable.

II. Bodies, where they come, bring their places along with them, and upon their Removal take them away. But EPICURUS was mistaken, in that he supposed a Place to be a Space subsisting of it self, which is equal to the Body placed, in Magnitude, and really distinct from it: For if we precisely have regard to the Notion of a Place, we shall find it to be nothing else, but a certain Respect of the Situation of a Body, to the Neighbouring Bodies about it; or to others more Remote, from whence it takes its immobility. So that to say a thing is in a Place, or acquires a new Place, is no more than to say, that it attains or acquires such a Situa∣tion, with respect to other Bodies. And it is a meer Mistake of the Mind, to imagine a Place to be a certain Capacity or Interval, which Bodies enter into, and leave again; forasmuch as Bodies do indeed bring their places along with them, and upon their Removal take them away again. And therefore we say, that a Body takes up some space, forasmuch as it is of such a Bulk amongst the other parts of the Universe, and is ranked amongst Material things: And that it quits a place, when it ceaseth to keep its Magnitude, Figure and Situation between such and such determinate Bodies.

III. Whether there can be any Motion, without allowing an Empty space. Another Argument, whereby EPICURUS endeavours to establish a Vacuum, is taken from the Nature of Motion. If, saith he, there be no Empty space in Nature, neither is it possible that there should be any motion; and consequently the whole Universe would be nothing else, but a stiff immoveable Mass, and unable to admit any Bo∣dies into it self. For supposing all Spaces to be full, a Body will be incapable of removing it self from one place to another, but by thrusting ano∣ther out of its place; so that if we suppose any Body to be moved, it must of necessity thrust another, at least of equal bigness with it self, out of its place; and that also must do as much for another, and so it will be necessary to allow a Process to Infinity, except that some Empty spaces be allowed, into which the Bodies that are in Motion may enter, and, as it were, take up new Lodgings.

IV. In every Motion, a whole Cir∣cle of Bo∣dies moves together. This Argument of EPICURUS might be of some force, if there were no other motion, but that which is made in a strait Line; and if when one part of the Matter is moved, the other follow∣ing were moved for ever; but daily Experience teacheth us the contrary, and that indeed there is another Motion, that is, a Circular, by which a Body, when it is made, doth drive another out of its place, and that again another and another, till it come to the last Body, which enters the place of the Body that was first moved. Now this Circle * 1.1can be performed without the supposal of any Vacuum. As suppose we the hollow Circle XYZ, fill'd with 12 Bullets, whilst the first of them A moves, it pusheth on the second B, and that the third, till by continual pushing, the place which was left by the first Bullet, be fill'd by the last Bullet C. And thus we see how motion may be without granting any Empty space, to which Bo∣dies might betake themselves.

V. An Obje∣ction a∣gainst the Circular motion of Bodies. If you Object with GASSENDUS, that the Bullet A cannot move, except the twelfth Bullet C be moved also; and that C cannot move, because, in order to its motion, it is necessary that A do possess the place of B, which as yet is not conceived to be empty, and that therefore as long as B con∣tinues unmoved, neither can A be moved; and that consequently all the Bullets contained in the Circle will continue unmoved.

VI. The Obje∣ction An∣swer'd. I Answer, That this Objection of GASSEN∣DUS is built upon a false Supposition, whilst he imagins that the Bullet C cannot move, except there be some Empty space whereto it might betake it self, when it begins to move; since it may so happen, that at the same moment when A enters the place of B, C may leave its former place; so that whilst the Bullet A passeth towards B, it pusheth B forwards, and B that which is next to it, &c. unto C, which at the same instant enters the place left by A.

The thing will be more evident in a Grind-stone, or in an Iron Circle, which is moved about its own Center; for since every part of it doth at the same instant possess the place which is quitted by the fore-going, we see there is no necessity to have recourse to a Vacuity. For if this may be done in an Iron Circle, why may it not as well be done in another, partly consisting of Wood, and partly of Air? Why may not the Body A, which we sup∣pose to be Wooden, push the Body B, which is Airy, out of its place, and B again that which is next to it, and that again another till it come to C, which will take up the place of A, at the very same time that A quits it? The same may be illustrated by the Circling of the Water about a Ship under Sail.

VII Why Water sometimes mounts up∣wards. Accordingly we find, that as much Liquor as runs out of any Vessel, so much Air must of ne∣cessity enter into it; and except there be an open vent for the Air to enter, it will be in vain to endeavour to draw the Liquor out of the Vessel; because wherever this Circular motion is hindred, it is impossible for a Body to remove out of its place. Thus when the Air is drawn out of a Pipe, the other end whereof stands in the Water, the Water immediately mounts upwards, notwith∣standing that that motion is contrary to its Gra∣vity.

VIII. All Bodies move toge∣ther, tho' it be in an Unequal Circle. And that it happens thus in every Circle, is easie enough to be conceived, especially where this Circle is supposed to be perfect, so that all its Parts are at an equal distance from the Center. But the same doth not seem to happen where the Circle is unequal, and whose Spaces are different in breadth and narrowness, as appears in the Circle EFGH. But this Difficulty is easily solved, if it be con∣sider'd that all these Inequalities may be compen∣sated or made up by swiftness of motion. For sup∣pose * 1.2we the Space G to be 4 times broader than the Space E, and double as broad as the Space F and H, it must necessarily follow that the matter must move 4 times more swiftly at E, than at G, and twice as swift at F and H; and thus, because the swiftness of the motion makes amends for the narrowness of the place, there will in the same Space of Time as much Matter pass through one part of the said Circle, as through the other: So that there is no necessity at all to feign Empty spaces, or to admit of Condensation.

IX. It is not necessary, that all Motion should be C••rcul••r. But when we say that Bodies move in a Circle, we must not be so understood, as if we suppos'd that all motions were either Oval, or perfectly Circular; but only that they are called Circular, because the last Body which is moved by the im∣pulse of another, doth immediately touch the First Mover; tho' the Line which is described by all the Bodies that are moved, by the motion of that one B••dy, be very crooked and irregular.

X. How it comes to pass, that a little round piece of Leather wetted, is able to lift up an hea∣vy Stone. From what hath been said, an account may be given of that Experiment so common with Boys, viz. how it comes to pass that a little round piece of Leather is able to lift up a great Stone; the Reason whereof is, because the Stone A, hanging on the String B, by means of the Leather C, to which it cleaves or sticks fast, cannot fall down from the Leather, without the Air that is under the Stone be first driven out of its place, and come into the place of the Stone, under the round bit of Leather: But forasmuch as before the Stone can fall down from the Leather, there must be a slit or opening between the Stone and the Leather, before there comes to be a greater Interval be∣tween * 1.3them, capable to receive or admit the Air, as being thicker and more expanded, because of the intercurrent Aethereal Matter; it so happens, that because the Circle of Bodies is hindred, the Stone of necessity must stick so long to the Leather, till the Air be driven away from under the Stone, and get in betwixt the Leather and the Stone.

XI. Whence the Diffi∣culty we have to conceive the Motion of Bodies, in a Space full of Bo∣dies doth arise. The Difficulty we have to conceive the motion of Bodies where there is no Vacuum, proceeds from a Supposition we have taken in, that GOD at the Beginning divided Matter into Equal parts, Round, Square, Triangular, &c. According to which Con∣ceit, we cannot imagine how possibly they could move, without leaving Empty spaces between them. And indeed, granting this Supposition, it could not be otherwise: But indeed we must go upon a quite contrary Hypothesis, and conceive that GOD at the Beginning, divided the Matter into Unequal parts, infinitely differing in Bulk and Figure; which suppos'd, it will be easie to comprehend that a Body may move where there is no Vacuum, but all full of Bodies, as well as in a Vacuum; for let it be Square, Round, Oval, or of any other Figure whatsoever, the Spaces which are between it, and the Bodies that surround it, will not be empty, because there will be always Particles of Matter Subtil enough for to enter and fill them, and be∣sides will be endued with sufficient agitation to break them; and by breaking of them, reduce them to Figures proper to fill the places they are to enter.

CHAP. III. GASSENDƲS his Experiments exami∣ned, whereby he endeavours to prove, that there are Vacuities in Bodies.

I. Gassendus, his Expe∣riment drawn from a Wind Gun, to prove a Vacuum. THere is no question, but that Experiments are the best Proofs of Philosophical Truth, and that those Principles are most likely to be true, which are built and founded upon Natural Phae∣nomena, and have them to be the Witnesses of their Evidence. And therefore it is that GASSEN∣DUS endeavours to prove the Existence of Empty Intervals in the World, by Arguments drawn from Condensation and Rarefaction. Suppose, saith he, a Wind-Gun, and that the Bore that contains the Air is of the length of 2 Fingers; there is no question, but that as much of the Air is therein contained (if no Empty Spaces be intersperst be∣tween the Parts of the Air) as the place, or capa∣city of the Bore is able to contain; so that there is no part of the place so little, to which a part of Air, of equal Bigness, doth not answer, and con∣sequently

the parts of both must be equal in Number.

II. It is re∣pugnant for one and the same Body to be in more places at the same time. Suppose also this Number to be 1000, then let the Air be compressed with an Instrument fit for that purpose, and by that means be reduced to the measure of a Fingers length only. What order will these parts of Air afterwards keep, when at that time, of the parts of Place, there are not above 500 left? Or shall we suppose that 2 Bo∣dies are crouded into one and the same place? This is repugnant to the Laws of Nature, since Impenetrability is the Property of a Body; and it is as much a Contradiction for 2 Bodies to be in the same place, as for 1 Body to be in divers places. Wherefore if the Particles of Air, contained in the Bore of the Wind-Gun, be shut up in a more narrow place, it is necessary that their Sides and Angles should be more closely lodg'd, and fill up the Intercepted Empty spaces; which being once fill'd, it cannot be thought strange, if by this means the Interval be made so much the lesser, and less protuberant than it was before.

III. The true Reason of this Expe∣riment given. But GASSENDUS in alledging this Expe∣riment, doth not seem to have heeded the Proceed∣ings of Nature; for tho' naturally Penetration be repugnant to Bodies, yet must not we inferr from thence, that there are Empty spaces in Bodies, which may receive the ambient Air, or contain any other Matter; seeing that it is very possible, that amongst the thicker parts of Air, there may be some more Subtil matter, which coming forth from the Pores of Bodies, may make that the Space which seems to be fill'd, may admit other Air. Because the Air that is thrust in by force, doth drive out the Subtil matter; which giving way to it, doth break forth through the Pores of the Gun. Wherefore the Compression of the Aiery parts doth not proceed from the filling of the Empty spaces, but from the Expulsion of the Subtil matter, which gives way to the parts of Air; whilst they come nearer together, and either make the Pores less, or quite take them away.

IV. From the Nature of a Body. For this is a Consequence which is deduced from the Nature of a Body or Matter, that when a Body appears under a less Bulk than it seemed to be of before, tho' it doth not appear that any part hath been taken away from it; we must conceive that some very Subtil matter is come forth from the Pores of that Body, and thereby have made the Parts come closer together, and reduced the whole Body to a less compass.

V. What an Aeolipile is. The next Experiment produc'd by GASSEN∣DUS, is that of an Aeolipole, which is an Instru∣ment made of Copper, or of some other Metal; the whole hollow whereof is at first fill'd with nothing but Air, which becomes so dilated by being set near to the Fire, that the greatest part of it, breaks forth from it through the Hole D, * 1.4which Hole is afterwards plung'd into a Vessel full of Water; and as the Air of the Aeolipile be∣comes condensed again by the Coldness of the Water, the Water riseth to fill it. This being done, care is taken so to place the Aeolipile, as that the lower part of it may rest upon glowing Coals, which causeth the Water that is contain'd in it to be rarefied into Vapours, the first whereof being push'd on by those that follow them, make their escape together with the Air through the said Hole D, with so much swiftness, that they pro∣duce a very sensible Wind, which continues to blow continually, till all the Water be evaporated, or that the Heat do cease to rarefie the Water into Vapours.

VI. The second Experiment of Gassen∣dus against a Vacuum, fetch'd from an Aeolipile. Let us suppose therefore the Aeolipile ABC DE, and one part of it ABC, to be fill'd with Water, and the other AEC with Air: Now the Enquiry is, how it can be, that tho' the Water which is contained in this Vessel being rarefied by the Fire, do break forth with great violence through the Hole of it; yet the whole hollow of the Aeolipile, doth still continue as full of Matter as it was be∣fore. For if the parts of Air AEC, and the parts of Water ABC, were equal in number before the Aeolipile ABCDE, was put near the Fire to be heated; the remaining parts, after that some of them have been evaporated, must needs take up more place: And therefore like as a Heap of Dust being toss'd with the Wind, becomes diffused and spread abroad like a great Cloud, be∣cause of the Air that is intermixt with the parti∣cles of Dust, why may not the particles of the Air and Water contain'd in the Aeolipile, being put into agitation by the little Bodies that have been introduc'd, take up the whole Space, which before was taken up by the intersperst Vacuities?

VII. The Expe∣riment of the Aeoli∣pile ex∣plained. But to this I answer, that there is no Conse∣quence in all this, because the parts of Water AB C, contain'd in the Aeolipile, are not therefore dilated, because they take up the Empty Spaces, which before were intermixt with the parts of Air AEC; but only because the Aeolipile being set upon the Fire, the heat thereof sets the particles of the Water in motion, and makes them to push against each other, and with great striving endea∣vour to get further from each other. For the Subtil matter, which hath been introduced by means of the Fire, doth distend and dilate their Pores; so that such as are more closely compressed, and do strive to disentangle themselves, break forth with violence through the Hole D, towards F, and resemble the Blast of Natural Wind. Wherefore the Dilatation of the Water, upon the Surface AC, is only to be attributed to the Subtil matter, which is entred through the pores of the Aeolipile, which agitating the particles thereof, doth not permit them any longer to hang together; according as GASSENDUS himself doth acknowledge in these Words; And this by the Activity of the particles of Fire, which being entred into, and most swiftly tossed between the Sides of the Aeolipile, do not suffer the Parts of the Water to rest; but drives them up and down, this way and that way, so as that they seem to fill the whole Space.

VIII. A third Experiment fetch'd from the Dissolution of Salts There is yet another Experiment whereby GASSENDUS supposeth that Vacuities are certainly proved: For he considering that a deter∣minate quantity of Salt only could be dissolved in such a Measure of VVater, and that having taken in as much as it can, it leaves the rest of the Salt undissolved; this he thinks cannot be solved any other way, than that the Salt being separated into very small particles, doth every way penetrate the VVater, and fill the Empty Spaces that are in it; which being done••, the further dissolution ceaseth in the same manner, as a Stomach that is already glutted with Food, doth cast up whatsoever is super∣added. And forasmuch as the Particles of Salt are not all of one Figure; for those of Common Salt

are Cubical or Four-square, those of Alom 8 Cor∣ner'd, &c. Spaces of a different Figure must be assigned to them; and that there are such, may be easily proved, because VVater already impregnated with common Salt, doth notwithstanding after∣wards dissolve and take in Alom, Salt Armoniack and Sugar. Which admission of several Bodies, cannot be imputed to any other Cause, but those Empty spaces which are between the parts of the VVater; because when they are once fill'd up, the VVater can dissolve no more of these Salts, as having no Vacuities where to bestow them.

IX. How Salt is dissolv'd in Water. This Experiment would be of some service to GASSENDUS, if he could persuade us, that the Bulk of the VVater is not at all increased by the dissolving of Salt, and that it takes up the same Space it did before; whereas indeed daily Expe∣rience teacheth us the contrary. For tho' in a Cup full of VVater, a certain quantity of Salt may be dissolved, without spilling any of it, yet not without some spreading of its Surface: For it is evident, that by the putting of Salt or Ashes into VVater, the Surface thereof swells, and jets out in the midst, in the manner of a Globe. As may beseen in a VVeather-Glass, or Glass-Pipe, into which if any Salt be infused, the VVater presently increaseth and mounts higher.

X. Why a cer∣tain and determi∣nate quan∣tity of Water, can dissolve a certain quantity of Salt only. But you'l say, If there be no Vacuities in the VVater to admit the particles of Salt, how comes it to pass that it is satiated with a certain quantity of it, and rejects all the rest? This may easily be answer'd, by supposing that the parts of Salt are stiff and inflexible, whereof those of fresh Water are very soft and flexible. For when the parts of Salt lye athwart one another, they give occasion to the parts of the fresh VVater to run or slide between them, and like Rings to encompass them round, and to dispose them so that they may the more easily glide between them, and continue their motion, than if they were all alone. For the parts of VVater being entangled with the parts of Salt, the Subtil matter, by whose force they are agitated, have no other business, but to carry them swiftly round the particles of Salt, which they embrace. Whereas, when they are alone, and constitute the fresh VVater, they are so confounded together, that the Subtil matter is forced to employ part of its strength, in variously bending and plying of them; seeing that without the impulse thereof, they con∣tinue immoveable, and cannot be separated from each other. Forasmuch therefore as the parts of fresh VVater are finite, and that the virtue they have to move themselves is limited, it must necessarily hap∣pen that after they have encompast a certain num∣ber of the parts of Salt, they will not be able to overcome the resistance of the rest; and therefore the VVater being as it were satiated, will not be able to dissolve the superadded Salt; because there are no more flexible parts of the Water, to surround or embrace the particles of Salt, by winding of themselves round about them, and by that means cause a liquefaction of them. This is manifest in Common-water and Aqua-fortis, which can only dissolve a determinate quantity of Salt or Metal; so that if after they have received this proportion, if one should but cast in over and above one grain of Salt, it will remain as much indissolved, as if it was laid up in a dry place.

XI. The Reason of all Crystalli∣zations. And for this Reason it is, that hot Water that hath run through Nitrous Earth, and thereby be∣come a Lye, by having taken in a quantity of Nitre, being removed from the Fire, and let rest for some time, many of the Atoms of Nitre, sepa∣rated from the rest, begin to cease from motion, and sticking to the inward Sides of the Vessel, do con∣stitute the wonderful 6 Corner'd Bodies; whence we may easily apprehend all the Crystallizations of the Chymists, and how they are done.

XII. The fourth Experi∣ment, of a Pipe of Glass, fill'd with a certain proportion of Quick∣silver. It remains now only, that we endeavour to assign the Reason of that Experiment, which TOR∣RICELLIUS made at Florence, as GASSEN∣DUS informs us; which take as follows: Having taken a Glass-pipe of 3 Foot long (according to the description of it in the 17th Chapter of the 6th Part of our Philosophical Institution) 7 Fin∣gers breadth, and 9 Inches long, fill'd with Quick∣silver, and having stopt the Mouth of it with his Finger, he dipt it into a Vessel with Quicksilver, and then found that upon taking away of his Finger, all the Quicksilver did not run out of the Pipe into the Vessel, but continued in the Pipe to the height of 2 Foot and almost 3 Fingers breadth, after ha∣having made some Vibrations upwards and down∣wards, and in the mean time leaving the upper part of the Pipe, not only destitute of Quicksilver, but of any other Body whatsoever.

XIII. The true Reason of the fore∣said Expe∣riment. This Experiment, tho' it be highly esteemed by some, as that which seems manifestly to evince a Vacuum; yet is it of no account with those who admit pores in Bodies, which are penetrable by the Subtil matter, and take up those places which are quitted by Grosser Bodies. For such is the Nature of the Matter of the First Element, that it doth not only pierce Glass, but even Diamonds and Steel it self, and any other hard Bodies what∣soever. For tho' Glass may seem to be destitute of Pores, yet it cannot be question'd but that it is endued with continual Pores, without any inter∣ruption; which is evident from its Transparency. For when it is in fusion and liquid, the Subtil matter flowing around all its parts, doth form innumera∣ble pores in them, through which the Globuli of the second Element do enter, and diffuse the Action of Light every where. Where tho' that Space in the Pipe, which is relinquish'd by the Quicksilver, seems to be Empty; yet nothing hinders, but that it may be fill'd with some very Subtil matter, which is not subject to our Sight. Neither was GASSENDUS ignorant of this, who in his Explication of this Experiment doth allow, that the Bodies of Heat and Cold can penetrate into the Hollow of the Pipe. And he holds the same con∣cerning the Light, which he owns to be a Corporeal Substance, and a very thin and Subtil matter which passeth through the Sides of the Glass. Wherefore it is without all Reason, that from hence he endeavours to prove Empty spaces, seeing that in those Intervals that are fill'd with Subtil matter, there is as much room to admit other Bodies, as if it were altogether empty, and without any Body at all in them.

XIV. That there is no Va∣cuity in the Glass-Pipe. Moreover who doth not know, that Nothing is not capable of any Properties; but if Fire be ap∣ply'd to the upper part of the Pipe, we shall find a like Rarefaction to be produc'd there, as we per∣ceive in the Weather Glass, and by means whereof the Quicksilver is driven downwards. When it is very clear, that there is some true Matter there, which is the Subject of this mutation.

XV. How the Existence of such a Subtil Matter may be proved. Now such a Matter as is much more subtil than Air, not only PLATO and ARISTOTLE, but all the ancient Philosophers have owned, which enters the pores of all Bodies, and intimately insi∣nuates it self into them: For by means hereof the Juices, which during the Winter season the Earth conceals in her Bosom, being agitated upon the approach of the Spring, do pierce the pores of Plants and Seeds; but after that the too great increase of Heat hath more dilated the Pores, or that the Cold hath overmuch straitned them; then the Juice either passeth directly through them, or by reason of the narrowness of the Pores, cannot enter them at all; and consequently the Seeds or Plants must dye. So that in the whole Vegetation of Plants, we meet with nothing, but a motion derived from this Subtil matter, and proceeding according to certain Rules: So likewise it is an effect of this Subtil matter, that Glass taken out of the Furnace, and set in a Cold place, pre∣sently breaks to shivers, because the Pores of the outward Parts are sooner shut up by the Cold, than those which are more inward; and therefore the greater parts of the Subtil matter that are shut up in them, hinder the Egress of the rest. Neither pro∣bably is there any other Reason to be assigned, why Glasses break of themselves. And to this we may likewise add, that it is from this Subtil Aether, that fluid Bodies are enabled to preserve their Mobility, and do presently corrupt, whenever their motion is disturbed or interrupted: For the principal Office of this Substance is, to dispose and incline the Parts of Bodies, and more especially such as are fluid, to the Laws of its motion. Neither can any thing else preserve the certain and natural motions of any Body. Conclude we therefore, that nothing hinders, but that the Subtil matter may enter through the Pores of the Glass, and fill that part of it which the Quicksilver hath left.

XVI. The fifth Argument, taken from united Bo∣dies. LUCRETIUS seems to have found out a stronger Argument than all the rest, for the Proof of a Vacuum, which is this: If two most exactly polisht Bodies be apply'd to each other, and touch one another, it will be impossible to remove the one from the other, but that at the same Moment the whole Surface of the one would be removed from the whole Surface of the other. For tho', it may be, in one part of the said Surfaces they might be more distant than in another; yet as soon as they began to open, they would no longer in any part touch each other, save in the opposit extream Line: For otherwise the said Bodies could not be smooth and even, but crooked and uneven, which is contrary to this Hypothesis. Which being sup∣posed, let the Air move with never so great swift∣ness, yet it can only successively pass the Space which is from the utmost Edge of the Surface, to the midst of these Bodies; and therefore it is ne∣cessary, that at that point of Time wherein the Air passeth the Edge or Brim, there must be con∣ceiv'd an Empty space reaching to the midst of the Surface of those Bodies, which is not filled, but during the Consequent Moments of Time.

XVII. There are no Bodies in Nature, that are exactly polisht. GASSENDUS takes this Argument to be convincing, and that it doth not admit any An∣swer; but if we well examine what it supposeth, we shall discover it to be false and without any ground. For it supposeth 2 Bodies exactly polisht, when himself (Phys. Sect. 1. Lib. 6.) denies, there can be any such: For tho' Marble, Iron, Wood, and other such like Bodies, in which we can perceive none of the least unevenness, neither by our Touch or Sight, seem to be most exactly polisht; yet Reason will tell us, that they must of necessity be very uneven, because all this polishing is the effect either of Grains of Sand, or of the Prominencies of Files, which cannot but leave Cavities, and consequently an uneven Surface behind them. And therefore it is not at all probable, that there can be found any 2 Bodies so even, hard and perfectly polisht, as that no Air should be intercepted betwixt them. But if ever 2 Bodies exactly polisht happen to be joyned together, then can they not be separated by pulling the one of them upwards perpendicu∣larly, but it will be necessary to draw the upper Body away Sideling, and by this means the sepa∣ration of these Bodies is performed, not in a mo∣ment, but successively; so that the Air doth not easily and readily succeed in the place that is left by them.

CHAP. IV. Of the Divisibility of Bodies.

I. Divisibility is a Pro∣perty that agrees to all Bodies. EPICURUS, who asserts that Material Sub∣stance is compos'd of Atoms, and to which he assigns the Rise and End of Things; imagin'd that Bodies were capable of being divided so long, till at last we come to such smallest Bodies, as by reason of their Solidness, do exclude any further division, and by no Natural Force can be any more resolved into Parts, as AUSONIUS hath it:

The Principles of all this Building tight, Are very small, and such as scape our Sight; Consisting all of Ranks of Atoms fit, Which solid are, nor parting do admit.

II. Gassendus his Opinion concerning the Divisi∣bility of Bodies. This Opinion GASSENDUS endeavours to defend, deriving his Argument from the Dissolu∣tion of Concrete Bodies: For as we see, saith he, that Nature resolves Bodies into exceeding small Particles, and in this dissolution proceeds only to a certain number of them; so we ought to conclude, that Nature doth not still divide Bodies smaller and smaller to Infinity, seeing that her Force is bounded, and within a short time becoms exhausted, and ceaseth; and therefore after the utmost of her Activity there must remain Indivisibles, and that cannot admit any further Partition.

III. An Indi∣visible Body is a Contradi∣ction. I know very well, that GASSENDUS doth not attribute a Mathematical Indivisibility to Atoms, but only supposeth them to be Indivisible, because of their Solidity, and the indiscerpible co∣haesion they have of their Parts; but which way soever GASSENDUS may endeavour to explain EPICURUS his Sentiment, Indivisibility seems to be repugnant to the Nature of a Body. For Divisibility is the Property of every Material Substance, and so intimate to it, that it doth imme∣diately and essentially follow the same: For if we carefully heed the Conception we have of a Body, we shall find it to be something Extended, and Commensurate to 3 Dimensions: But how can it be that that which is Extended, and consists of Longitude, Latitude and Profundity, should not be Divisible? Conclude we therefore, that every

Body is Divisible, and capable of an indefinite Di∣vision, so as that it can never be exhausted by any Partition whatsoever.

IV. Forasmuch as Inf••••te Points a••e assignable in a Body, it must follow, that every Body is infinitely Divisible. This Division is variously demonstrated by Mathematicians: We shall give you one Instance, that may serve instead of the rest. Let us sup∣pose parallel Lines AB and CD, and the same as to their length Indefinite, and a Fingers breadth distance from each other: This suppos'd, the Line EF, which intervenes between the foresaid Paral∣lels, and that perpendicularly, must of necessity be a Fingers breadth long. Then taking the Point A, of the Line AB, which we will suppose also to be a Fingers breadth distance from the Line EF; let us take above the Line CD, to the Right hand of the said Line EF, as many Points as we please: As for Example, G, H, D, &c. distant from each * 1.5other at pleasure; and let us conceive, that from the Point A, so many Right lines do proceed, as to reach to the several Points G, H, D, &c. This granted, it is manifest that the Line AG, will cut the Point I, of the Line EF; the Line AH, the Point L, a little Higher, and the Line AD, the Point M, which surpasseth the former, or is drawn about it; and so of the rest. But because the Line CD, is Infinite, and that therefore an Infinite number of Points may be taken in it, it follows, that all the Lines that shall be drawn from the point A, to all the foresaid points, will denote Infi∣nite points in the Line EF, and they different amongst themselves, and which will still more and more approach to the End E, yet so, as that none of all the said Lines will ever pass through the point E; because it is suppos'd that the Line CD, is parallel to the Line AB. Whence we conclude, that since an Infinite number of Points can be assigned in a certain determinate portion of Matter, that Matter is infinitely divisible.

V. How it comes to pass, that all Bodies are not Equal, seeing that all are infinitely Divisible. Some one or other, it may be, will object in favour of GASSENDUS his Hypothesis; that if it belongs to the Nature of a Body, to be Divi∣sible to Infinity, it will follow, that any Body will be equal to another, which is double its Bigness: But what greater absurdity can there be, than that 2 Bodies of different Magnitudes should be Equal? and consequently it must be false likewise, that they are both of them Infinitely Divisible. The Major is evident, because there is an Infinite Divisibility in the Smaller Body, as well as in the Greater, which notwithstanding is twice bigger than it.

VI. A Finite Mind can∣not deter∣mine any thing con∣cerning that which is Infinite. This Objection may be answer'd, First, by saying with DES CARTES, in the First Part of his Principles, Article 26, That we need not trouble our selves too much, to explain or extricate these Difficulties, which are not proportionate to our Intellect, and which cannot perspicuously and distinctly be conceived by us. For it appertains only to Infinite Mind, to understand that which is Infinite, and to determine any thing concerning it. Wherefore it would be a great piece of Folly, to reject the clear Notion we have of the Nature of a Body, as false; because we are not endued with an Infinite Understanding, and therefore cannot comprehend that which is Infinite. Wherefore also DES CARTES considers all those things wherein we can perceive no Bounds of Extension, not as Infinite, but as Indefinite; because they can be indefinitely divided, and we can never come to the last part of them.

VII. Two Bodies of different bigness, may be di∣vided into as many parts the one as the other, tho' not into as great parts. Or, Secondly, we may give this Answer to the foresaid Difficulty, that the Divisibility which is in the lesser Body, is not so much as that of the greater Body, which is twice as big; that is, the lesser Body cannot be divided into Parts, that are as big as those into which the gre••ter is divisible; but yet it may be divided into as many; because Bodies are not said to be Divisible with regard to their Continuous Quantity, but with respect to their Discrete Quantity; for the Thousandth part of one Body may be divided into other 1000 parts, no less than the whole Body: Forasmuch as the Divisibility of a Body, or its aptitude to be divided, is not diminished by actual Partition, no more than the Faculty of Writing or Painting grows less in a man, whilst he writes upon Paper, or paints upon a Board or Cloth.

VIII. There are innumera∣ble parts in the Body of a Mite. It will seem a Paradox to some, that there should be as great a number of Parts in the little Body of a Mite, as in that of a Horse, an Ox, or an Elephant; yet if we will be pleased to make use of a good Microscope, we shall find that the Body of a Mite is every whit as Organical, as that of the most bulky Animal; for we find it hath a Bill, with a long Trunk, wherewith it pierceth the Skin, and draws Blood thence for its Aliment. It is seen also sometimes to cast forth Dung, of the bigness of a Flea; besides which many Asperities may be perceived, as well on the outside, as on the inside of its Skin, and 2 branching Horns on its Fore∣head, and 6 Feet on each side, like to those we see in Crabs, long-wise extended from the sides of it, 2 whereof support the fore-part of this little Ani∣mal, and the other 4 the hind-part. But tho' all these outward parts of this little Animal be consi∣derable for their number, yet are they but very few, if compared with many parts which lye hid in the inside of it. For it must have a Stomach, Guts, a Heart, a Brain, wherewith to perform the Functions of Life. It must also have Veins, by which its Aliment may be conveyed throughout all the parts of its Body; Arteries, to conveigh the Vital Spirits; and Nerves, to convey the Animal; besides, Muscles, Tendons, Joints, and innumerable other parts conducive to its Nourishment; Sensibility and Capacity of moving it self, and exerting all the other Functions of Life. All which Parts, tho' they be very small, yet are they no less divi∣sible than those which are much greater, because they are extended, and separable into Parts.

IX. GOD can produce Animals infinitely lesser and lesser, than others. Wherefore seeing that the Demonstrations con∣cerning the Divisibility of the Matter are clear and evident, we may assert, that there may be Bodies, yea, and Animals too, still less and less than others, and that into Infinity, tho' our Imagination can frame no Conception of them: For why might not we say with ••ufficient certainty, that all Ani∣mals are in little in their Seed? Seeing that we see in that which we call the Treadle of an Egg, (which was never set upon) a Chicken, which for ought we know, is entirely formed; and that we see whole Frogs in the Spawn of Frogs. It is also very probable, that in the Bud of a Mustard-seed, and of the Kernel of an Apple, by Example, there are infinite Trees; because it not only contains the Tree, whose Seed it is, but also a vast number of other Seeds, which it may be, contain within them also other Trees, and other Seeds; which other Seeds do probably contain still other and more

Trees; and other Seeds, as fruitful as the first were, and this to Infinity.

X▪ The Bodies of all men mor•• pro∣duced from the Begin∣ning of the World. Neither may we only conclude, that Plants are contained in the Buds of their Seeds, but that all the Bodies of Men, and of Animals, that shall be born for the future, even to the end of the World, probably were produced from the first Beginning of the World: I mean, that the Females of the first Animals, have probably been created, with all those of the same Species, which they have al∣ready brought forth, or shall do to the end of the World.

CHAP. V. Of Loose and Close Bodies.

I. A Sponge becomes distended and swell'd by Liquor. A Sponge, by letting in of Water, or any other Liquor, swells and is pufft, and ••preads it self into a larger Bulk.

Some suppose that a Sponge is rarefied by the increase of some new Quantity; as if nothing of Foreign Matter did enter into it, but only that some ••upervening Quantity doth separate the parts of the Sponge, and increaseth its bigness. But who can believe that when Water is rarefied, and in a manner turned into Air, it is only thus dilated by the increase of new Quantity? Who perceives not that the Sponge sucks in Moisture, and hides the same within it self, which afterwards upon the squeezing thereof, runs out again, whereupon the Parts come closer together. A Sponge therefore becomes rarefied or dilated, when the parts of it are somewhat removed from each other, and that the Pores of it are fill'd with supervening Water. And the same Sponge again grows close, when its Parts are brought nearer together, by the Expul∣sion of that Matter, which before kept them at a greater distance. So that a Sponge may not only be said to be a Loose Body, whilst it is dry and free from all Moisture; but also, and more especially, when it hath all its Pores fill'd and stufft with Foreign Bodies.

II. Why some Bodies are more apt to be rare∣fied than others. Glass becomes dilated to a greater Space by Heat, than Metals; and of Metals, Iron is more dilatable than Copper; Copper, more than Silver; Silver, more than Gold; and Pewter more than Lead.

The Reason of all which must be fetch'd from the greater Porosity of those Bodies that are more light than others; for the more Pores there are in any Body that is capable of being Rarefied, the more Bodies may insinuate themselves into it, and by this means it becomes rarefied or distended.

III. The motion of Rare∣faction is more intense at the beginning. The Curious Searchers of Nature observe, that the Motion of Rarefaction is more intense at the beginning, and more slow and remiss towards the end thereof. They produce several Experiments to prove this; and more particularly from that of Weather-Glasses, exposed to the Heat of the Sun, uniformly, and continually applied to them; or set in Water that is kept in the same degree of Heat.

The Reason whereof is, because Rarefaction being caused by the admission of some thin Sub∣stance into the Pores, the more the said Pores are dilated by the violent ingress of new Matter, the more the Parts of the Body rarefied become distended, and therefore do still more and more resist and oppose any further distension.

IV. What is the Reason that Gates and Dores do easily shut in dry weather, and more hardly in Moist and Rainy. Gates and Doors frequently cannot be shut or opened, in Moist weather, without some difficulty: Whereas the contrary happens in the Boards where∣of Barrels are made, which when expos'd to the Air in Dry weather, do open and make the Vessels to become leaky.

The Reason is, because Gates or Doors do swell in Wet weather, for that the Water, or the Air fill'd with watry Vapours, penetrates the Pores of the Wood, and distends the Sides of them, which being dilated, the whole Bulk of the Body must needs be di∣stended likewise, and take up a greater Space than it did before. In like manner Linnen-Cloth is rare∣fied by the Accession of Water, Water by that of Air, Air by that of Aether, and Aether by that of a more subtil Body, if any such there be, and by this means take up more Room than they did before.

V. Why the Strings of an Instru∣ment do swell by the Moi∣stness of the Air. Thus also the Strings of a Violin, or other In∣strument, do swell in Moist weather, as appears by their breaking, and by the difficult winding of the Pegs. In like manner wooden Bowls are apt to get Slits, if they be put into Water, and the Water penetrate them. Some very credible Authors re∣late, that Earth taken up from those parts that are near to the River Nile, do increase every day in weight, from the time when that River begins to swell, until it be arrived to its greate••t height. Which cannot proceed from any thing else besides the Air; which being condensed at that time, and clogg'd with watry Particles, doth increase the weight of the Earth.

VI. How an Obelisk, moved out of its station, was put to rights again. By the same means an Obelisk at Constantinople, which was got out of its place, was put to rights again; for the Artificer, who had undertaken the Work, having caused very strong and thick Ropes to be tied to the Obelisk, and fastned to some strong Hold fast, caused the said Ropes to be moistned, by pouring great quantities of Water upon them, which causing them to swell, and consequently shortning their length, lifted up the Obelisk to its former situation upon its basis. For Ropes, con∣sisting of long and twifted Threads, by admitting the Moisture into their Pores or Intervals, the more they swell in thickness, the more contracted their length is.

VII. How Mil∣stones are separated from the Rocks, whereof they were a part. It is after this manner that Mill-Stones are sepa∣rated from the Rocks. For they make abundance of Holes about the said Rocks, into which they drive wedges of Wood that have been dried in an Oven; which Wedges being placed around in the form of a Cylinder, according to the bigness that we would have the Mill-Stones to be of, when Moist weather comes these Wedges swell, and by their swelling separate the Mill-Stones from the rest of the Rocks; so that it is evident, that this Separa∣tion is made by the Vapours, which would be very difficult to perform any other way.

VIII. VVhy the Staves of Barrels are contracted in hot and dry wea∣ther. The Staves of Barrels take up less room in Dry weather; for seeing that their Parts are agi∣tated by Heat, some of them fly away into the Air; which being gone, it is no wonder if the rest come closer together, and do not take up so much place as they did before.

IX. A Bar of Iron put into the Fire, swells and be∣comes di∣lated. Take a Bar of Iron, for Example, of 2 Foot long, and a Stick or piece of Wood of the same bigness; then put the Iron Bar into a strong Fire, till it be red-hot, and then compare it with the piece of Wood which was of the same dimensions with it, when it was first put into the Fire, and you'l find the Iron to have been increased, not only in Breadth, but in Length also, and in both

to exceed the Piece of Wood which was equal to it before; but as soon as it is grown cold, we shall find it restor'd to the same dimensions it had before it went into the Fire.

The Cause whereof is the subtil Body, which enters the Pores of the Iron, viz. the particles of Fire, which dilate it to a greater Extension. For the parts of Fire being in continual motion, must needs distend the Sides of the Iron Bar; which when expos'd to the Air, and being cooled, returns to its former Extension, because the particles of Fire leaving its Pores, and those of the Air entring into them, and not being moved with the swiftness and violence that those of the Fire are, they do less distend them, and consequently the Bar of Iron must take up less room than it did before.

X. Why a hot-Iron cuts Glass. Hence also it is, that with a Red-hot Iron, or with a piece of Packthred dipt in Brimstone and set on fire, Glasses are cut; because the particles of the Glass being agitated by the heat of the Fire, require a greater Space, and consequently drive their contiguous Parts further from them. And it is for the same Reason, that Metals in fusion swell, and take up more room than they did be∣fore.

XI. Water ra∣refied into Vapour, takes up an hundred fold larger Space, than it did be∣fore. Water, by the virtue of the Sun, is lifted up into the Air, and becomes thereby so diffused, as to take up a greater Space than it did before; for if we may believe the account that some give us, Water turned into Vapour, fills a Space 100 times larger than that was which it took up be∣fore.

The Cause of which Diffusion is not to be at∣tributed to the parts of Water, as some falsly do imagine; since it is impossible that the Dimensions of a thing should be increased, except that some other Body be added to it. And consequently the Water becomes dilated, when its Parts remove farther from each other, and so give way for the entring of some Foreign Body between them. After the same manner as when a Heap of Dust, by the Wind is lifed up, and dispersed in the Air: For this Expansion is not to be attributed to the particles of Dust; but to the Air, which fills the Intervals between them, and separates the particles of Dust from each other.

XII. Why Bodies that are condensed, become of a white Colour. Condensed Bodies, and such as after Rarefaction are reduced to a less Room, are commonly of a white Colour; as Butter, Grease, Oil, and such like.

The Reason whereof is, because in Condensation those particles are expell'd, which swell'd the Grease or Oil into a greater Room, whereupon their parts must needs come closer together, and be con∣tracted, as it were, into small round Pellets, which afterwards, like so many round Looking-Glasses, do reflect all the Light, and produce a white Colour in the condensed Subjects. For there are two things especially, by means whereof Bodies acquire a white Colour: The First is, That they consist of little and innumerable Surfaces, disposed to receive and reflect the Light in such a manner, as that it may suffer no loss, either by Refraction, or by the mixture of Shadow. The Second is, That the whole Light which shines upon a Body be re∣flected, without having any Beams swallowed up in the Pores of it. To the effecting whereof little round Bodies do conduce most; as will appear, when we come to speak of Heat.

XIII. What is the Cause of Fermen∣tation in New Beer or Ale. New Beer or Wine, if it be put into Bottles, doth swell and work with that Violence, that it fre∣quently breaks them.

Which Fermentation is caused by the Hetero∣geneity, or the Diversity of the parts of Liquor; which cannot unite together, by reason of the variety of their figures, and therefore endea∣vour to extricate themselves from the Society of each other. And that this is the true Cause of the Fermentation of Liquors, appears from hence, that after these Liquors are separated from their Heterogeneous parts, they are no longer agitated with any such tumultuary Motions; as is evident in Burning Spirits, Distill'd Water, and the like; which may be kept a long time without suffering any Change. For the Spirit of Wine being kept closely stopt, is not capable of any agitation of its parts; but if a little Turpentine be mixed with this Spirit, the parts presently begin to tumultuate, and endanger the breaking of Vessels Hermetically sealed.

XIV. Bread made of sprouting Corn fer∣ments of it self. If Bread be made out of the Flower of grown or sprouted Wheat, it will ferment and rise with∣out the addition of any Leaven of Yest.

The Cause whereof is, because the stiff and sharp particles of sprouted Wheat do infold them∣selves; and, as the Chymists express it, are in their greatest Exaltation: Wherefore, as soon as the Dough begins to grow hot in the Oven, the parts thereof become tumultuarily agitated, and driving the resisting Bodies before them, do in a manner prae∣cipitate them, and by this means the Bread be∣comes spongy and light.

XV. How the Air comes to be con∣densed or rarefied in a Wea∣ther-Glass. Let a Weather-Glass be fill'd with Aqua-fortis; but so as that when fill'd, there may be some Space left, taken up by the remaining part of the Air, which was before in the Glass, Tube or Pipe: You'l find that this part of Air, be∣ing dilated by a more intense Heat, upon the recess of the Aqua-fortis, retiring it self into the lower Head of the Tube, will fill the whole Capa∣city of the Tube; and that on the contrary, by Cold it will be contracted into so narrow a room, as that the whole Tube almost will seem to be filled with the Aqua-fortis.

Which Variety proceeds from the continual ingress of new Matter through the pores of the Glass, which doth so rarefie the impure Air con∣tained in the Glass, that by the separation of its particles from each other, it drives the Aqua-fortis, being unable to resist its place; whereas upon the egress of the subtil Matter through the Pores of the Glass, the particles of the Air com∣ing then closer together again, the Aqua-fortis returns to its former place, being drawn into it by the Air that enters at the lower end of the Glass. And if the weather be very Cold, that part of the Air which is in the upper part of the Glass, upon the recess of the subtil Matter, doth so greatly decrease, as that the whole Glass becomes fill'd with the Aqua-fortis.

XVI. Why a Chest-Nut cast into the Fire breaks with a great noise. A Chest-Nut put into the Fire, first swells, and soon after bursts, giving a great Report. Which doth not proceed from any foreign Matter that enters the Chest-Nut, but from the grosser parts of it, which the action of the subtil Matter entring into the Pores thereof, separates from each other, and doth so agitate, that at last they burst the Shell with a great noise.

XVII. How a Marble Pillar was broken to shivers. In like manner, a vast Marble Pillar mentioned by CABAEUS, was broken all to shivers, by kindling a Wood Fire round about it: For the heat of the Fire rarefying the Air contained in the Pores of the Marble, makes, that it cannot be lodged in the narrow Room it took up before, and therefore in striving to get forth into a large Space, it breaks and rends the Marble to pieces.

XVIII. The vast dilatation of a grain of Gun-powder. This Dilatation of Bodies, is the Cause some∣times that a very small Body becomes diffused into an incredible distension; as we see in Smoak, Va∣pours and Flame, which Dilatation is so great, that one Grain of Gun-powder, according to the De∣monstration of Joh. Chrysost. Magnenus, when kindled, becomes dilated into a flaming Sphere 3804 times greater than it was.

CHAP. VI. Of Hard and Fluid Bodies.

I. Whence the Hard∣ness of Stones and Gems does proceed. BOdies are distinguished by Hardness, as Stone, Wood, Whet-stone, Pumice-stone, Gems or Precious Stones; some whereof are broken with ease, and others not without great difficulty.

We account those Bodies Hard, the parts whereof are at Rest together, and are so closely united, as that they are not interrupted by any other Matter moving between them. And ac∣cordingly those things are accounted the most hard and firm whose parts are inflexible, and touch one another. And therefore Precious Stones, tho' they all agree in this, that the File will not touch them; yet some of them are harder than others. For some of them are polisht with white Lead, others with Copper, others with Emery. Thus we find a great difference there is betwixt a Diamond and Crystal, tho' both of them proceed from the same Matter, and grow in the same places; because Crystal is much more soft, its Parts being not yet firmly grown together, but agitated with various Motions. Whereas the Diamond is much more firm and compact, by reason that its insensible parts do more immediately touch each other, and are more intimately and close entangled by mutual cohaesion.

II. A Hard Body sus∣pended in the water moves more swiftly in a Right Line, than the VVater it self doth. When a Hard Body is suspended in the Water, if the Water move in a right Line, the said Hard Body will move more swiftly than the Water fol∣lowing the same Line.

The Reason whereof is this, because all the parts of a hard Body have but one and the same determination, and the several parts of the Water, or other Liquor, have every one of them theirs, which greatly retards their motion in a Right line.

III. A Hard Body, that swims upon the water, moves more slowly than it. upon the water of a River, moves less swiftly than the River: For tho' all the parts of the Hard Body have but one only determination, and those of the Water have many; yet is this over and above recompensed, by the less degree of Solidity in the said Body, which is the Cause that it keeps above the water, and so has fewer parts of water to push it forwards, and more of Air or subtil Matter to resist its motion.

IV. Why burnt Bricks are more hard than those that are not. Bricks, made of Clay, become harder by being burnt or bak'd in the Fire; notwithstanding that after their Burning they have larger Pores, and that their parts are further distant from each other.

I suppose, that this hardness of the Bricks is caused by the action of the Fire, which not only drives out of their Cavities the parts of water, which I conceive to be long and slippery, like little Eels; but also all their other fluid Parts, which are not very close joyned together. Whence it comes to pass that these being taken away, the remaining parts come closer together, wherein the Nature of Hardness does evidently consist.

V. Why some soft Bodies grow hard. From this new entanglement of the Parts it comes to pass, that many Plants in Brazile, which whilst they stand in the Ground are very soft and flexible, being pluckt up, within a short time after become inflexible and very hard. I remember to have read somewhere of a certain kind of Clay, which as long as it lies at the bottom of Rivers, and is cover'd with water, is very pliant; but being taken up into the Air grows hard immedi∣ately, and becomes very firm and stiff.

VI. How Wood comes to be turn'd to Stone. Yea, what is more, we find sometimes that Pieces of Wood are turn'd to Stone, and that by means of a petrifying Juice, which being got into the pores of the Wood; and the watry parts of the said Juice being exhaled, leaving the Earthy and Stony parts in the Pores of the Wood, impart to it the Weight, Hardness, and other Affections of Stones. For Wood thus changed into Stone, becomes thereby almost 6 times more ponderous than it was before; and the remaining parts of VVood are so closely entangled and joyned with the superadded Sandy particles, that they can no longer be consumed by the Fire.

VII. The way of preparing the Wood, whereof Musical Instruments are made. It is an unquestionable Truth, that Bodies which are agitated with a slow and intestine motion, do in process of time grow more hard and solid. For the Wood whereof Musical Instruments are made, require much time before they can be brought to the highest disposition and fitness for that use, even from the time of 20 to 80 years sometimes. They who make Vessels, and other Utensils out of Guajacum, tell us, that they must let it lye 20 years before it be fully fit for some of their uses. So much time is required, that all the Volatile and watry Particles being exhaled, the solid Parts may come more closely together, and attain that fit firmness and dryness which is ne∣cessary for them.

VIII. How Wa∣ter, Broath, Blood, &c. become hard. VVater becomes congealed into Ice; Broath, Blood, and the like into Jelly, and attain all of them to some degree of Firmness. Which happens, because their Particles, upon the ceasing of the outward agitation hang together, and more closely embrace one another. For Blood and Broath be∣come more firm by the Exhalation of their thin∣ner Parts, the thicker staying behind, which being closely entangled together, are fixed by the rest. The same we experience likewise in Oil of Annis∣seeds, which in the heat of Summer continues fluid, and stands in need of a Vessel to contain it; but at the approach of VVinter, when the Solar Beams do more weakly beat upon the Earth, it becomes a hard Body. So likewise Milk, which of its own Nature is fluid, and doth easily insinuate it self into other Bodies, yet becomes coagulated

into Cheese, when the slender, stiff and sharp Par∣ticles that are in the Rennet, have penetrated the substance of the Milk, which by agitating the particles thereof, drive the branchy flexible parts together, and by their weight expel the smaller particles of Whey out of their places. Milk also is turned into Butter, when the parts of Cream being agitated by perpetual Churning, are sepa∣rated from the rest, and by their Branchy particles entangling together, do unite into one continuous Body.

IX. Why Wa∣ter riseth higher in the lesser Branch of a crooked Glass-Pipe, than in the greater. The water which is in a Crooked Pipe of Glass, riseth higher in the less branch of it▪ than in the greater. Because there are more Lines of Air, that act upon the Liquor that is in the great Branch, than upon that which is in the lesser: Whence it follows, that if the Liquor stop in the great Branch at AB, it will not stay in the lesser at GE, which is level with AB, but will mount upwards towards D where I suppose that the weight * 1.6of the water, which is above the Level GE, doth compensate or make good the inequality of the pressions of the Lines of Air, which act upon both the Branches. Wherefore seeing that this Inequality is by so much the greater, by how much the Mouth of the little Branch is less, or narrower, because the lesser the Hole is, the less power the Air hath to exert its activity upon it; therefore the less the Hole is, the higher will the water mount above the Level. This is no more than Experience confirms to us: For when the Pipe is about the thickness of a Quill, the water mounts only the height of 2 or 3 Lines; whereas if it be so small that scarcely a Horse-hair can enter it, the water will mount the height of 10 or 12 Inches above the Level.

X. Salt is dissolved in Water, by the motion of it. Salt melts in Water, notwithstanding that it is more ponderous than Water, and sinks to the bot∣tom.

Which happens, because the parts of VVater being in continual motion, do insinuate themselves into the particles of Salt, and having dissolved their connexion, do separate them from one another and spoil their Continuity. For this melting or disso∣lution of Salt, cannot be brought about without motion: For tho' the Water, which is contain'd within the Hollow of a Glass-Vessel, seems not to move; yet considering the fluidity of VVater, we must conclude, that some of its insensible Parts are continually moving upwards and downwards, as well as from side to side of the Vessel: By which agitation the parts of the Salt become dissolved, and are separated from each other.

XI. How Metals are dissol∣ved in the Stygian Waters. Thus also Metals are dissolved in Acid Spirits, and that within a short time. And for the same Reason it is, that when Oil of Tartar per deliquium is instill'd into these Stygian waters, it produceth a great ebullltion or effervescence. And it is for no other Cause, that Bread or any other spongious Body, if it be but slightly dipt in water, is spoiled thereby, than this, that the Particles of the water being in continual agitation, do enter the Pores of those Bodies, and by this means make a sepa∣ration of their parts from each other.

XII. How fluid Bodies come to be hard. Liquid Bodies do frequently become hard and firm: Thus the white of an Egg, by boyling, becomes hard.

This Hardness proceeds from the Contexture and Figure of their parts, whereby they are so adapted together, as to cling to one another as it were with Hooks and Holdfasts, so as that after∣wards they can no more continue their motion. Thus the most highly Rectified Spirit of Wine, and the Rectified Spirit of Urine, being poured together, joyn and coagulate in the form of Snow. Because the dissolved Sulphur, which con∣stitutes the Spirit of VVine, having insinuated its little Branches into the Pores of the sharp Volatile Salt of the Spirit of Urine, doth so link the parts together, and reduceth the Pores of that Com∣pound to such a narrow compass, that the Matter of the First and Second Element, which passeth through them, is not capable of imparting to those Liquors their ordinary Fluidity▪ and by this means are reduced to the consistence of a kind of Hard Body. The same effect is also produced by mixing Spirit of VVine with the beaten VVhite of an Egg. And it is for the same Reason that Spirit of Turpentine, after reiterated Distillations, is turned into a hard Body.

XIII. How com∣mon Water, impregna∣ted with Saltpeter, grows hard. Common-water, that hath run through Earth that is impregnated with Nitre or Saltpeter, and set upon the Fire to boyl, continues as Liquid as ever; but being removed from the Fire and gr••wn cold, it sets a Mass of Salt, and becomes Cry∣stalliz'd.

The Reason whereof is, because the VVater being grown cold, many of those particles of Salt, which were agitated by the heat of the Fire, cease their Motion, and coming closer together, embrace one another; and by this means are Crystallized, and return to their former figure: Alom yielding 8 Corner'd Crystals; Salt Armoniack 6 Corner'd; Sea Salt, Cubical or Square; Salt Nitre Pyrimi∣dal; and other Salts, Crystals of other Fi∣gures.

XIV. How a Sillibub is made. When any Sowr Liquor is poured into warm Milk, immediately the Curds are by this means separated from the VVhey; as appears in that Drink so familiar amongst us here in England, called Sillibub.

This Separation happens, because Milk is not altogether fluid, but is of a somewhat thickish consistence, whose Pores are encompass'd with grosser parts, which are the Curds whereof Cheese is made: And therefore when any sharp or subtil Liquor enters the same, such as Vinegar, Cider, or the like, it drives away the grosser Particles, that fill the Pores, which thereupon joyning together, become separated from the VVheyish part. The same also happens when Milk is kept so long that it turns sowr; for then, without the assistance of any Rennet or foreign Liquor, it is precipitated and falls down to the bottom, especially if it be set near the Fire; because when Milk grows stale, its thinner parts become fluid, and being sowred with the warmth, serve instead of sowr Liquor or Rennet, to run the Milk together.

XV. Oil cannot be taken out of a Cloth by Water, but well with Soap. Oil cannot be washed out of Cloth with water, but Lie must be us'd, or Soap, which is not so fluid as water, but by its consistence appears to be en∣dued with a far less degree of Motion.

The Cause whereof is, because the Parts of VVater, as to their Figure, differ from those of Oil, and therefore cannot penetrate or divide each others Parts: For the particles of Oil are Branchy, whereas those of VVater are slippery, and much in the shape of Eels: For which Reason also they

enter the pores of a Cloth stained with Oil, and leave the particles of Oil untouch'd. For Water hath not the force to enter into Oil, or to penetrate into the inmost parts of it, and consequently can∣not carry off any parts of the Oil with it. Whereas Lie, because of the Salt that is mixed with it, doth readily perform it; for the parts of Salt being stiff and inflexible, and therefore like so many Darts piercing into the parts of Bodies, doth easily loosen the particles of Oil, and being mixt with water, easily carries off the Oil with it. And hence it is that Soap is of so great use, for the taking of Spots or Stains out of Cloaths, be∣cause it consists of Salt, Oil and VVater. For the little particles of Oil, because of their familiarity, are easily united, which the water extracts by being joyned with the particles of Salt.

XVI. What is the Cause of the Rising or Falling of water in a Glass. When any Liquor is put into a clean Glass Vessel, having an even Brim, and fill'd up to the top, the Surface of it appears plain and even; but not so when the Vessel is only fill'd in part, because then the surface of the Liquor seems to be concave or hollow in the midst.

The Cause hereof is, because the Air in the former case doth with an Equal force press upon the Liquor; nor can any Reason be assign'd, why it should press one part of it more than another. Whereas in the latter case, the Air being whirl'd round about the Glass with water, whilst from abroad it enters into the hollow of the Glass, it is not so much dispos'd to turn its Force towards the Sides of the Glass, as to continue its motion towards the midst of the water; and consequently presseth the Liquor more in the midst, than towards the Sides of it, which therefore are somewhat higher than the midst, which by the greater pressure of the water sinks somewhat lower.

XVII. VVhence water comes to have a round Figure. But if you pour into a Pipe, or other Vessel, some∣what more water than it is well able to hold; because that part which is ready to spill over the brims of the Vessel, is more expos'd to the Air, than that which is elsewhere; therefore the Air drives it by its pressure more towards the midst, where is the fittest place for it to swell or rise higher. Thus we see that the water in this Pipe or Vessel swells above its brim, and that the swelling or Rounding thereof comes nearer to a perfect Round in a small or narrow Pipe; because where the Vessel is very large, the Force of the Air is not strong enough, to overcome the weight of such a great quantity of water.

XVIII. VVhy a Leaden Bullet is more easily beat flat upon a Cushion, than on an Anvil. A Leaden Bullet being laid upon a Cushion, or a pendulous Anvil, is more easily beaten flat, than upon an Anvil that stands fast and immove∣able.

The Reason is, because it is not sufficient to the beating of a Bullet flat, to strike it with a great force; but it is over and above requisite that this Force continue for some time, that the parts of the Bullet may have leisure to alter their situation: But when such a Bullet is laid upon an immove∣able Anvil, the Hammer leaps back almost the very same moment it strikes the Bullet, and so hath not time enough to flat it, as it hath when it can continue longer upon it, as when it is laid upon an Anvil or other Body that gives way to the stroak of the Hammer, and doth not by its Soli∣dity immediately beat it back. Thus the Shin∣bones of a Sheep are more easily broke upon the hand, than upon an Anvil; because the Hand, by giving way to the force of the stroke, assists the breaking of it.

XIX. How a Leathern Ball or Bladder is made hard, by the Air that is blown into it. When Air is blown into a Leathern Ball or Bladder, it makes it to become hard, tho' the Air of it self hath nothing of Hardness in it.

The Reason is, because the parts of Air that are pent up in a Leather Ball, or Bladder, being unable to penetrate the Parts thereof, are by this means so much comprest, that thereby they are forced to change their figures, and bend like so many little Bows, which endeavour to return to their former and natural posture; and by this means so distend the Ball, and make it feel hard to the Touch.

XX. Liquid Bodies are ponderous, proportio∣nably to their height. Fluid Bodies, that communicate with other fluid Bodies, are Heavy, proportionable to their Height, and not according to their Breadth. As for Instance, Let us suppose a Vessel full of water ABCD; having 2 Openings or Mouths of unequal big∣ness E and F, to which are soder'd 2 Pipes like∣wise unequal, such as G and H. This supposed, if you pour the same Liquor into the said 2 Pipes * 1.7to the same height, both the Liquors will be in an Equal poise.

The Reason is, because their Height being the same, they are in proportion to their Thickness; that is to say, if the Hole E be double to that of F, there is also twice as much Liquor in the Pipe GE, as there is in that of HF; whence it follows, that the Liquor of the great Pipe cannot sink 1 Thumbs breadth lower, but it must make that in the lesser Pipe to rise 2; nor can that of the lesser sink lower by 2 Thumbs breadth, but it must make that in the greater Pipe to rise 4 Thumbs breadth, which makes an equal quantity of motion on either side, and consequently the water continues in equal poise in both the Pipes.

XXI. VVhy a Beam of wood lies unmoved in the water, tho' the parts of the water are in continual motion. A Hard Body, for Example a Beam of Wood, being in the midst of a Pond, continues unmoved; and except by outward force it be put into motion, it always observes the same distance from the Bo∣dies that surround it.

Which proceeds from hence, for that the Parts of the Fluid Body, which every way encompass the Wood, are tost with various motions, some upwards others downwards, some to the Right, and other to the Left; so that the Wood receiving all their contrary motions, rests in an equal poise between them all; since there is no cause that might incline it one way more than another. But if the whole Fluid Body tend one way, the Wood will be forc'd to comply with its motion, and be carried along with it; because in this case the Contrariety of the motions in the water is removed, by the waters running one way only.

XXII. VVater sometimes conduceth to the Hardness of Bodies. The Plaister wherewith the Walls of Houses and Roofs are cover'd, grows hard by its being mixed with water, and by this means acquires a firmness, which it never had before.

Some do imagine the Cause hereof to be from the sudden evaporation of the parts of Water, which by being sublim'd into the Air, leave the rest of the Body hard: But Experience teacheth us the contrary; for if Plaister of Paris be weighed whilst it is almost Liquid, and be afterwards weighed again, after that it is grown hard, it will be found to have lost nothing of its weight.

For my part, I suppose this Hardness is produc'd, because in the Plaister there are many Pores, which the Fire hath formed in it, and are such as that the thicker Particles of Air cannot enter into them, because they have not strength enough to remove those Obstacles which they meet with in the Plai∣ster; which yet the particles of Water can do. Whence it comes to pass, that the water having been variously agitated with the Plaister, by flow∣ing about the Grains or Clots of it, variously opens the Pores of it, and divides it into much lesser Parts than it was before: And forasmuch as these Particles, by being reduced into most fine powder, have acquir'd more Surface than they had before, when they were yet in Clots, being now joyned together by a more immediate contact, they do constitute a hard Body.

XXIII. Why Ce∣ment be∣comes as hard as Marble. And it is for the same Reason, that a Cement made of Flower, the White of an Egg and calcin'd Stones, turns as hard as Marble, wherewith the Sides of that wonderful Fish-Pond at Cuma is walled. So likewise it is a thing well known, that the Powder of Flints and Loadstone being mixed with the white of an Egg and Sanguts Draconis, doth within a few days become an exceeding hard Mass.

XXIV. Why aque∣ous Liquors are easily resolved into Va∣pours; but fat and Oily Li∣quors not so. Aqueous and volatile Spirituous Liquors are easily resolved into Vapours; whereas fat and oily are not without much difficulty exhaled.

The Reason is, because the parts of the former, are endued with very simple Figures; whereas those of fat Liquors are of more intricate Figures, like Branches of Trees, by which means they hang and cling close together, and therefore cannot without difficulty be separated from each other.

CHAP. VII. Of Rough and Smooth Bodies.

I. Many Bo∣dies that appear smooth and polisht to sight, are rough not∣withstand∣ing. MArble, Steel, Wood, &c. appear smooth; but yet are found to be rough by the help of a Microscope.

The Reason is, because Bodies are commonly polish'd with the help of very hard Powders, the grains whereof cannot but leave Cavities, and con∣sequently Unevenness in the Surfaces of the Bodies so polished. Pumice-stone is also made use of to this purpose; because by its Roughness, it rubs and wears off the Prominences of the parts. And with these hard Powders always some Water or Oil is mixt, which prepares the matter, and conveys the powder into all the Cavities of the Stone, or other Subject that is to be polished. But however, after all the pains that is taken, Art can never so polish Bodies, but that some insensible Prominences and Subsidences will still remain.

II. Glass and Crystal are not abso∣lutely smooth Bodies. Thus Glass, Crystal, and the like, tho' they seem to be the smoothest of all other Bodies: Yet may truly be said to be Rough; for tho' Glass be made by fusion of the smallest particles of Ashes, yet forasmuch as they are irregular and angulous, they cannot be so bent by the force of Fire, as to cling closely together, and by this cohae∣sion to lose all their own Figures: For tho' the protuberant Corners of Glass may be worn off somewhat, yet can they never be so adapted, but that some of them will get out beyond their Fel∣lows. And tho' this Unevenness of the parts of Glass be not visible to us, yet must we not there∣fore deny it, because we know that our Senses are not sufficient to discover all the Affections of Bo∣dies, and often mistake in those things, which Reason proves to be most clear and evident. A Line drawn upon a Paper doth appear strait; which beheld through a Microscope is found to be crooked, and to have many Inequalities.

III. The most exactly polisht Bodies are Rough. In like manner, there are many other Bodies which to our Sight and Touch seem to be absolutely smooth, whose Surfaces notwithstanding are made up of most thin prominent Filaments, with their Intervals, according to the demonstration Micro∣scopes afford us of them. Thus Mr. HOOK hath demonstrated the strange asperity and roughness of the Point of a Needle, and the smoothest Edge of a Razor, Micrograph. Obs. 1 & 2. Yea, all Metals, how polish'd soever, and Lead also, not∣withstanding its great compactness, represents great Asperities to the Eye that consults them, assisted with a Microscope.

IV. Rough Bo∣dies gene∣rally cast something of a white Colour. Bodies that have a Rough surface, commonly cast a whitish Colour; but being moistned with water, they draw to a blackish Colour.

The Reason is, because Rough Bodies consist of many Faces, many whereof are so turned towards us, that howsoever the Rays of Light fall upon them, they reflect copious Beams to our Eye, and consequently produce Whiteness. But when the Surface of a Rough Body is wetted with water, these Unevennesses or Faces are taken away, which before did reflect the Rays of Light, and consequently must make it appear of a darker Colour.

V. Smooth Bodies have one part more shining. Polisht Bodies reflect the Rays they receive to∣wards one part, which therefore becomes more bright and shining than the rest, which rather appear obscure and darkish.

Which proceeds from hence, because the Ex∣pansion or spreading of the Rays reflected from Bodies, is produced from the various Inclination and Eminence of their Parts. And therefore Arti∣ficers do cut and grind Diamonds into several Angles and Surfaces, that from them the Light might be variously reflected and diffused. Thus Silver Vessels, when boil'd in a white-wash, be∣come white as Snow, but if after this, any part of them be polished, they lose their whiteness, and become brown and darkish, and like Looking-Glasses, reflect their Rays towards one place only; because the eminent particles, which were the cause of their Roughness, are taken away by polishing, and therefore it cannot be otherwise, but that that Light which falls upon them, must be directed to one certain place. As we see in an Iron Breast-piece, which being polisht, at some∣times, appears very bright and resplendent, and at others dusk and dark.

VI. Why two polisht Marbles are not without difficulty separable from each other. Two Pieces of Marble exactly polisht, do so closely cling together, that the lowermost of them by▪ its own weight cannot fall down from the uppermost; no not in case a much heavier weight be applied to it, to draw it down, nor can it be separated from it, but by very great force.

The Cause hereof is to be fetch'd from the weight or spring of the Air, which presseth the two pieces of Marble together. Wherefore seeing that the parts of all Bodies that are here with us,

are prest against each other, by the superincumbent Air, or the ponderous Exhalations and Effluvia of Bodies, it is obvious to conceive how much the simple Contact of the small particles of any Body, according to their whole Surfaces, doth conduce to the causing and preserving of the firmness of Bodies; not precisely, because the parts do touch one another; but because, together with that Contact, there always is an outward Cause, viz. the weight of the pressing Air, which is able to preserve that Contact, till by a greater Force supervening they be separated from each o∣ther.

VII. Whence the Mossiness and Moul∣diness of Bodies doth arise. Some Bodies are very subject to grow mossy and mouldy, as Houses that are cover'd with Tiles or Thatch, the outside of Walls, and Ground that hath not been tilled of a long time.

This Mossiness and Mouldiness is caused, when the lesser particles in their Exhalation out of Bodies, are seized by the Grosser and Bigger, and are hin∣dred from flying away and leaving the Body; for by this means, being mutually entangled, they stick fast to the Surface of it, and turn into a kind of Down. Thus we find, that old Trees breed more Moss than others, because their Juice is not so well digested as to spend it self all in Branches and Twigs; but because of its weakness is stopt in its way, and covers the Bark of the Tree with a kind of mossy Down.

VIII. VVhy a Pumice-stone can∣not be polisht. A Pumice-stone, and several other sorts of Stone, are not capable of being polisht.

The Reason is, because the Pumice-stone is a porous Body, and its pores are so wide, that the parts of it can never be brought by any Art to the smoo••hness of polisht Bodies; but after all that can be done towards the polishing thereof will appear rough to the Touch.

IX. No abso∣late smooth∣ness can be found in Bodies. From what hath been said, we find reason to conclude, that there is no Body which can be said to be absolutely smooth. For, First, the most smooth and polisht Bodies have Pores, and conse∣quently so many Cavities, which are inconsistent with absolute Smoothness. Secondly, The Artifice that is used for the polishing of Bodies being per∣formed by Whetstones, or very hard Powders, can∣not but leave some Unevenness upon them, as we find by the Microscope in the Surface of the most polisht Steel, or the smoothest Edge of a Razor. And so likewise it cannot be otherwise, but that hard Powders, used by Glass-Grinders, must leave streaks and furrows, tho' imperceptible, to the un∣assisted Eye. So that whatsoever is commonly spoken of the smoothness or evenness of Bodies, must only be understood with respect to the Senses, but not absolutely.

X. Polisht Bodies do more strongly act and resist, than Rough Bodies. Polisht Bodies exceed Rough Bodies in the force of Acting and Resisting, as may be seen in Knives and Swords, which when Rusty, cannot cut or penetrate Bodies so well, as when they are whetted and smooth.

The Reason is, because Rough Bodies have their Surfaces very uneven, some of their parts jetting out, and others subsiding: Which Unevenness of the Surface is a great hindrance to motion, and is the cause why the Bodies that are struck against them, do more faintly rebound from them. Thus we find, that a Ball will rebound much further from a smooth, than from a rough Body, which those that play at Ball are very well aware of; and accordingly, neither can it be any wonder that a smooth and sharp Knife doth cut better and more readily, than another that is all cover'd with Rust.

CHAP. VIII. Of Transparent and Opake or Dark Bo∣dies.

I. Why some Bodies are more trans∣parent than others. SOme Bodies are almost wholly pervious to the Rays of Light, and reflect but few of them: Others resist the free passing of the Beams, and in some parts only suffer the Beams to pierce them.

This Transparency of Bodies consists in the direct or strait position and ranging of their Pores, with∣out any respect had to the Neighbouring Bodies, whether they be continuous or contiguous, because they make no change in the case. For supposing this strait position of the Pores, a luminous Object, will as well affect our Eyes, as a Colour'd will, and impress its Image on our Brain. But when this situation of the Pores comes to be changed, then the Beams of the luminous Body are either not transmitted at all, or do not clearly exhibit the Image thereof, but confusedly and difformedly; because they pass through the Body, not in Rank and File, but in a tumultuary hudling manner crowd through it.

II. Why Glass is more transparent than Paper Glass is more transparent than Paper, and admits a more free passage to the Light.

The Reason is, because tho' in Paper, as well as Glass, there be pores which admit the Light com∣ing upon them, yet are they not ranged after the same manner. For in Paper the pores are irregular and confus'd, by reason of the various entangle∣ment of the Threds whereof it doth consist, which obstructs the Action of the Light, for those pores which are open on the utmost Surface, as they go deeper, are obstructed by crossing Filaments. But in Glass there is such an Arangement of parts, that the pores are all continued in a strait Line, so that the Light most readily glides through them, according to that of the Epicurean Poet:

—nor can the Beams of Light Through any Body freely reach our Sight, Except the Pores in straitest Lines be rang'd, As they're in Glass—.

For Glass, when it was first made, and was yet in fusion, the particles of the Fire piercing it every way, formed innumerable pores in it, through which the Globuli of the second Element finding a free passage, are able to transmit the Action of Light, which consists in their pression, every way in strait Lines.

III. Transpa∣rency may be acquir'd several ways. There are several ways whereby Transparency may be produced: First, By melting: Thus we find that Snow and Butter by being melted, become transparent. Secondly, By the intrusion of some proper Body, by means whereof a due position of the Pores is introduc'd: Thus Paper anointed with Oil transmits the Light, and is made Diaphanous. Thirdly, By Resolution: Thus we see that the Waters or Spirits distill'd from Opake Bodies, as of Roses, &c. are transparent. Fourthly, By Concre∣tion or Coagulation, by which means the Diamond

and Crystal attain their perspicuity. Fifthly, By polishing and wiping off the Dust: Thus Glass by being polished, and after it is polished by being dusted, becomes transparent, and affords a free and undisturbed passage to the beams of Light.

IV. How Glass is made more dusk and ob∣scure, by the addi∣tion of new parts. The perspicuity of Glass is diminished by the same degrees, as it increaseth in Thickness and Bulk.

The Cause whereof cannot be assigned to ought else, but the Inequality of the Pores: For seeing that Glass is not altogether transparent, but con∣sists of many thick parts, which reflect the Beams of Light; it cannot be otherwise, but that many of its pores must be obstructed by the addition of new Matter, and consequently the Action of Light hindred. As we see that a man may, through the joyning of his Fingers, perceive Objects; but if he lay the Fingers of his other Hand athwart them, they will stop those little slits or gaps through which he could see Objects before. In the same manner, tho' a thin Glass does readily transmit the beams which fall upon it; yet will it stop and hinder the Sight, if it increase considerably in thickness, because its pores by this means are in∣terrupted and are made unequal. And it is evi∣dent, that the Inequality of the Disposition of the parts alone is sufficient to render that Opake, which before was Diaphanous. Thus we find that the Grains of Indian Sand, beheld through a Micro∣scope, are not only pellucid, but sparkle like Dia∣monds; but when by being heaped together they can no longer give free passage to the Light, they shew Opake or Dusky.

V. How Vint∣ners fine their VVines. It is a thing common with Vintners, to fine their Wines, that is, to make them clear and pellucid, by means of water-Glue, ordinarily called Izing∣glass, and the whites of Eggs; making use also sometimes of Alabaster, and calcin'd Flints, for the same end.

For the first of these, consisting of Viscous and Tenacious parts, do easily entangle the faeculent parts of the Wine, and sink with them to the bottom: And the other, have a Precipitating force or virtue; and therefore entring the Pores of the Wine, do precipitate the more dreggy parts of it. In like manner they correct Ropy-VVines, by adding to them burnt Alom, Quick∣lime, Plaister of Paris, Salt, and the like; for all these produce a new Fermentation in the Liquor, and so cause a separation of the grosser parts, which are sent down to the bottom. And by this means the VVine recovers its former consistence and pellucidity.

VI. VVater is more opake than a Mist. Tho' VVater seem transparent to the Eye, yet is it less pervious to the Light, than a Mist: For if a man, from the top of an high House or Tower, look down towards the Earth, he will be able to perceive it through a Mist; whereas he finds that his Eye-sight cannot pierce to see the bottom of a River, where the distance is as great from the Surface of the River to the bottom, as from the said high Tower to the ground. And therefore Divers witness, that after they are got 12 or 15 Cubits under water, they can neither perceive the Sun, nor any thing else. Which is an evident Argument, that the VVater is an Opake Body, and much more dusky than a Mist.

The Reason hereof in VVater seems to be the Thickness of its parts; which being irregular, and of unequal Figures, easily hinder the Globuli of the second Element from passing through them in strait Lines. For we must conceive a Body to become Opake, when the said Globuli cannot pass through it, but by oblique ways, and when their course is stopt by thwarting particles. Now a Mist is more transparent than the VVater, because it consists of thinner parts, and such as are more ready to comply with the motions of the subtil Matter, and easily make way for them: For tho' the parts of the Mist, as well as the VVater, be irregular; yet they differ in the Magnitude, be∣cause the particles of a Mist are more fine and subtil, and not so closely entangled, as those of the water. Whence it is that the Globuli of the second Element move them with more freedom, and more easily thrust them out of their places; which is the true Reason why a Mist doth less oppose the transmission of Light, than VVater doth.

VII. VVhy many Liquors are opake. VVine, Milk and Blood, with many other Liquors, are Opake.

And the Reason is, because they are not pure and simple Liquors, but are throng'd with many Heterogeneous Bodies. It is a thing very notorious, that VVine, when it is distill'd, leaves many Bodies behind, which will not rise in Vapours. And this is the reason of the great clearness of Spirit of VVine; for being by Distillation freed from all its Heterogeneous parts, which were an hindrance to the free passage of the Rays of Light, it becomes wholly transparent, and that in the highest de∣gree. Milk also is Opake for the same reason; for we find that when the Curds are separated from it, the VVhey is in a great measure Diapha∣nous. And the same is to be said of Blood, and other such like Liquors, which never appear thick or troubled, but when some strange Bodies are mixed with them, which obstruct or come athwart their Pores.

VIII. How Li∣quors are made clear and trans∣parent. Beer, Ale, and other Liquors, after fermentation become clear, and are not thicker or more troubled at the bottom, than at the top.

And this, because the Matter of the second Element, moving in the pores of Liquid Bodies, do continually drive the particles of the third Element out of their places, till they have so dis∣posed of them amongst others, that they do no more resist their motion, than those others do; or if they cannot so dispose them, till they have wholly separated them from the rest. Thus we see that New Wine doth not only cast some of its dregs upwards towards the Surface, and precipitate others of them downwards (which might be at∣tributed to the Lightness or Heaviness of the par∣ticles so separated) but also to the Sides of the Vessel. And the same estimate is to be made con∣cerning pure Liquors.

IX. VVhy Urine is some∣times clear and trans∣parent. So for the most part Urine is clear and trans∣parent, whilst the Heat helps to keep the pores more lax and open, and consequently leaves a more free way for the Light to pass: But when either the pores are contracted by Cold, or stopt with various little Bodies, they are the cause of the Opacity of the Urine. For indeed, there are but very few Liquors which are without any Opake particles.

X. VVhy our hands are commonly more dirty in VVinter, than in Summer. And for the same Reason it is, that our Hands, during the Winter, are more dirty; because the particles that should exhale through the Skin, continue sticking under it, and that because of the greater constriction of the pores, so that the exhaling Matter is hindred from flying away into the Air: Whereas in Summer time, when all the pores are open, all these gross Exha∣lations are carried up into the Air, and conse∣quently leave the Hands clean. Wherefore in Cold weather it is good to wash the Hands with warm water, to help to open the pores.

XI. VVhy Cry∣stal loseth its perspi∣cuity, when cast into the Fire. Crystal, if it be cast into the Fire, or for a Minute or two be cover'd with hot Ashes, it loseth its Diaphaneity, and seems to degenerate into a quite different Body; neither can it afterwards, by any known Art, be reduced to its former perspicuity.

Which can only be attributed to the particles of Fire, which violently rushing into the pores, do break their order, and consequently produce a new ranging of the parts. Now this confused dis∣position of the Parts, destroys perspicuity; as shall be shewed more at large, when I come to treat of Qualities.

XII. How it comes to pass that two clear Liquors mixt toge∣ther consti∣tute a black Body. It has been found by Experience, that from the mixture of 2 clear Liquors, a black Body doth arise: For the Infusion of Galls, which is clear, being mixed with a solution of Vitriol, makes Ink.

The Reason whereof is, because the particles of both these Liquors being mixed together, do so intimately close and unite, that by the closeness of their ranging, they hinder the passage of the Beams of Light. For in either of these Liquors there are certain little Bodies, which when joyned together, neither transmit the beams of Light, nor suffer them to reflect from the Body, but do, as it were, wholly swallow them and keep them Prisoners. But if you add to the Ink, Aquafortis or Spirit of Vitriol, it will become clear again, like Spring▪water; because the particles of this new infused Liquor, do separate the contiguous Bodies, and open the shut up pores. But if Oil of Tartar per Deliquium be added to the changed Ink, it will be restored to its former Blackness; because Oil of Tartar joyns it self with the Spirit of Vitriol, and the particles of the Galls and Vitriol do again embrace each other. It is also from the same Cause that Spirit of Wine, in which Annis∣seed hath been boil'd, when mix'd with water, yield a white Colour; and Oil of Tartar, when mixed with water, becomes troubled and opake; that is, because the order and disposition of their Parts is troubled, and the passage of the Aethereal matter hindred, by little super-added Bodies that obstruct the pores.

XIII. The Reason of the variety of Colours arising from the mixture of various Liquors. Hence it is that when we write with the clear and transparent Infusion of Vitriol, the Letters do not appear at all, except that the Paper hath been done over with the Infusion of Galls; but a Pen dipt in the Spirit of Vitriol will efface these Characters, which will appear again when drawn over with a Pen dipt in the Oil or Liquor of Tartar. And the cause is much the same in other Colours produced from the mingling of 2 clear Liquors. Thus the Salt of Tartar dissolved per Deliquium, being poured into a solu∣tion of Calcin'd Tin, gives a blew Colour; the same added to a solution of Lead in distill'd Vinegar, yields a white Colour; and being dropt into an Infusion of Mercury Sublimate, affords a yellow; Antimony Calcin'd with Nitre, and boil'd in com∣mon water, leaves the water that is strain'd from it clear and transparent. All which diversity pro∣ceeds from the various disposition of the particles whereof these Bodies are compounded, which causes the Rays of Light to receive a different Re∣flection from their several Surfaces.

CHAP. IX. Of Bodies that are Bended and Pressed together.

I. VVhat is the Reason that a bent Bow, as soon as slackned, returns to its former state. A Bow, made of Steel or Wood, being bent, returns to its former state.

The Reason whereof I suppose to be, because the pores of the Bow, by the bending of it, becomes so narrowed, that the subtil Matter cannot freely pass through them; and therefore pushing against them with greater force than ordinary, strives to make its way through them, as formerly. Now this may be done several ways; for if we conceive the pores of the Bow, before it was bent, to have been of an even widness from beginning to end, but that by being bent the ends of the said pores are narrowed, it is evident that the subtil Matter, which passeth freely through that part of the pores which is widest, when it comes to the narrow Extremities, will endeavour to disentangle it self, and pass further. But if the pores of the unbent Bow be supposed of a round figure, and that by the bending of it they are reduced to an Elliptical figure, the subtil Matter will exert its endeavour, to bring them to their former round figure, and con∣sequently will restore the bent Bow to its former state. For tho' the Globuli of the second Element, with respect to their bulk, are but of little force to shake the sides of the pores; yet because they con∣tinually croud in great numbers into the Cavities of the Bow, striving to make their way through them, all their Forces being joyn'd, and conspiring to this end, are sufficient to effect it.

II. VVhy VVires and the Bought of Trees, that are bent, return to their Natural posture of themselves. And it is for the same Cause that Iron-wire, made to wind spirally in Rings, like a Serpent, and shut up in a Box, as soon as the Box is opened, it leaps out of the Box, like a Serpent, shooting it self at some body. Thus also the bended Boughs of Trees, as soon as they are let go, fly back with great force and violence, so as to carry vast weights up with them: Because by this bending the parts of the Boughs are comprest together, which upon the impulse of the subtil Matter, striving to enter the compressed pores, are driven to their former state and posture.

III. Some Bo∣dies upon their being bent, re∣bound or fly back more strongly▪ others weakly. On the contrary, a soft Plant, such as is the Elder, flies back but a little; a Hazel tree, which is harder, more; because the foresaid subtil matter passeth with more ease through the open pores of the former, and with greater difficulty through the straiter pores of the latter. Thus Glass that is bent, returns with greater force; because the parts of it are not joyned by the mutual entangling of their Branchy particles, as those of Plants are, but only by their Surfaces: And therefore when the figure of the pores of Glass is changed, the subtil matter exerts a more forceable impulse to restore the same. A Proof whereof we have in a Plate of Iron, which by being much hammer'd, acquires

this force or spring to fly back. Thus likewise the Air it self, by being comprest and pent in Pneuma∣tick or Hydraulick Pipes or Instruments, when it is left to its liberty again, it dischargeth the ••ullets or water with as much force, as before it had been pent in and comprest; and all this from the at∣tempt of the subtil Matter, to restore the changed pores to this former state and figure.

IV. Why all the wa∣vings this way and that way, take up the same space of Time. A Cord or String fastned at both ends to fixed Bodies, being forced from its situation, runs out and returns, or waves this way and that way in the same measure of time, tho' it doth not always measure the same space of place.

The Reason is, because, as in a Body that hangs down, the several motions of the several Excursions are equal to the time of their Returns, by the Altitude of that Circle, the Arcs whereof are de∣scribed by the hanging Body: So in like manner in a stretched Body, all the Moments of time wherein the middle part of the String waves out one way, are equal to that one time, wherein the other Extream, in case it were cut loose, would strait pass through the whole length, and come to the place of the other, to which the unchanged force would still draw it back.

V. Why the Excursions of a string, are not equal to the degree of its being stretched. If you demand, why a String that is as long again, if it be equally stretched, doth make its Excursions as slow again as another: But if the String be stretched as much again, it doth not make its, Excursions as swift again; but to the end it may do so, the force of the stretching must be 4 times as great.

I Answer, that forasmuch as all the Excursions of every String, be they of what length they will, are equal to one and the same straight Traje∣ction, the Trajection in the former case, must needs be made in a double proportion of time; because a double Space is taken to be run through by the same motive Force: But in the latter case it cannot; because when we take three equal things, viz. Time, Space, and the motive Force, it must necessarily follow, that supposing the same Space to remain, as much as the time is diminished, so much the motive virtue must increase; and that there be the same proportion of the space to the time, as there is of the motive virtue to the space: Therefore it must follow, that if the space be in such a proportion to the time, as 2 to 1, the force must be to the space, as 4 to 2; and therefore must not have the proportion to time of 2 to 1, but of 4 to 1.

VI. Why Sticks break after that they have been long bent. Some Bodies that have continued long bent, do break, when we endeavour to reduce them to their former posture; as we find in some Sticks, which break whenever we go about to straiten them again.

The Reason whereof is, because the subtil Aether, whilst it endeavours to separate the par∣ticles of Bodies that resist its motion, must not only overcome the Resistance of them, but of the Bodies that surround it. And forasmuch as every thing endeavours to continue in the state wherein it is, and that Bodies which have been once put into motion, do continue in the same; so it is that the subtil Matter cannot shake them, without superadding more force to them, and increasing their strength; and so it comes to pass, that dashing more strongly against the said parts, it altogether separates them from each other.

VII. A Low that con∣tinues long bent, at∣last loseth its force of return∣ing to its former situation. A Bow that hath been long bent, especially if it be made of Wood or Steel, doth in process of time lose its force of flying-back, and continues in the same state, to which by bending it hath been re∣duced. A long Plate of Lead, bent in manner of a Bow, doth not fly back at all, but continues in the crooked state in which it is put.

The Reason why a wooden Bow, that hath been long bent doth not fly back, is, because its parts are not so hard, but that the subtil Matter can easily form new pores in them for its own passage; but a piece of Lead, bent like a Bow, cannot start back: For seeing that the parts of Lead are soft and flexible, they do easily suffer themselves to be penetrated; so that the subtil Matter can easily form new pores, and being able to pass freely, doth not make any attack upon the parts, whereby it might cause them to fly back. For as drops of Water, falling perpetually, do make an impression even upon the hardest Stones; so by the continual impulse of the subtil Matter, against the sides of the Oval pores in the bent Lead, they are adapted and accommodated to the free admission of the said particles, so as to let them go through without any Resi∣stance.

VIII. Why a Bullet doth more pene∣trate a Body at a distance, than one which is nigh to it. It is observed by some, that a Bullet discharged from a Gun, doth more penetrate a Body at 100 Foot distance, than at 10 or 20.

The Reason whereof is, because the Bullet being so soon beaten back, hath not space enough to perform so strong an effect: Something in the same manner, and for the same reason that a Hammer less flattens a Bullet when lying upon an Anvil, than when it is laid on a Cushion; as before was mentioned, Chap. 6. Of hard and fluid Bodies.

IX. Comprest Liquors take up less Room, than those which are put into Vessels, where they are not pent up. It hath been observed, that when a Vessel fill'd with Liquor is emptied into Bottles, and after∣wards the Liquor is poured out of them into the Vessel again, it will not fill the Vessel as much as before; and that it is more conspicuous in Wine, than in Water.

The Cause whereof is, because the Liquor is not so much comprest in an open Vessel, as in Bottles; and because in the former the Liquor meets with nothing almost, but parts of its own Nature; whereas in Bottles, the parts of the Liquor meet more with the parts of the Bottle, which so keeps them in, and compresseth them, that they cannot display themselves, as otherwise they would. As the Liquors are comprest by the Sides of the Vessels wherein they are contained; so likewise on the other hand are Bodies also comprest by the Liquors that are in them, but yet so as to be equally comprest in all the parts of them; because the parts of the Matter are kept in by each other in Equal poise, neither are they more prest in one place than in another.

X. VVhy •• Bellows held with the upper part under water, can∣not be opened or displayed. For the same Reason it is also, that a pair of Bellows with the Sides of it clapt together held under water, the Nuzzle of it standing out, can∣not be displayed or opened; forasmuch as the sides of it are comprest by the surrounding water, which will not give way, no not tho' great force be made use of for that purpose, especially if the Bellows be somewhat deeply sunk under water. Thus if you take a Vessel full of Quick∣silver, and fasten to it a long Pipe, the top whereof stands out of the Water, it will be so comprest at the

bottom of the VVater, that it will cause the Quick∣silver to rise somewhat in the Pipe.

XI. VVhy the Air breaks forth with such vio∣lence out of those Pneumatick Vessels, wherein it hath been comprest. Air that hath been comprest in a Pneumatick Engin, breaks forth thence again with extream Violence; as is seen in those Engins which cast up water to a great height, or shoot Darts or Bullets at a great distance.

Some take the Reason hereof to be, that the Air being strongly prest upon, is received into some empty Spaces, which before separated the parts of Air from each other. But suppose it to be so, what is the Reason that when the Hole of the Pneumatick Vessel is opened, the Air breaks forth so violently? For if every part of Air re∣tire it self into those empty Spaces, and preserves its former Extension, where is the Compression? And what is it makes the Air leap back with so much violence, if by being received into those empty Spaces, it does suffer no Violence?

The Cause therefore of this Elastick virtue, is, because the Air being thus comprest, its parts are not capable of dilating themselves as formerly: For being all of them flexible, and moving inde∣pendently on their Neighbours, they must every one of them have, as it were, a little Sphere, which may be sufficient for them to perform their Cir∣cular motion about their own Center in. But being comprest, they can have no such Sphere or Space to move in, since every one of them enters into the other place, and so hinder one another. And whereas the force of the Globuli of the second Element continues still to be the same, and shakes the parts of the Air, as much as before; they with their Extremities hitting against each other, and driving one another out of their places, at last joyn their forces, and make a general onset to deliver themselves from the said Compression, and procure more room for themselves.

Hence it is, that the Air which is comprest in a Pneumatic Vessel, whereof I have given the Figure in the Sixth Part of my Institution, Chap. 14. having water at the bottom of it, doth violently break forth, mounting up to a very great height.

XII. How it comes to pass, that the Air may be comprest in a Leaden or Pewter Vessel, but not in a Glass. Water contained in a Glass cannot be comprest, at least sensibly; which yet may easily be done, when it is in a Vessel of Lead or Pewter.

The Reason is, because the Compression of the water is always performed by the Expulsion of some subtil Matter, which lay hid in the pores of the comprest Body. Now because the Air, which is contained in the water, cannot pierce through the pores of the Glass, as it can those of Lead or Pewter; therefore this is the Reason, why water is capable of being comprest in a Vessel of Lead or Pewter. Thus we see not only, that water is squeezed out of Wool, Sponges, and other such like wet Bodies; but likewise out of Green-wood, and Air out of Dry-wood, when they are comprest by being put into water; as is apparent from the Bubbles arising to the Surface of the water.

XIII. A Bladder that is blown up with Air, being com∣prest, re∣turns to its former state of Inflation. A Bladder blown up, being comprest, riseth again.

Because the particles of the Air, which are shut up in the Bladder, being in continual motion, and whirling about their own Centers, they conse∣quently cannot, without difficulty, suffer themselves to be compressed; and therefore as soon as the pression ceaseth, they are extended again by the Agitation of the subtil Matter, and consequently dilate the Bladder, as before.

XIV. VVhy the VVind that is pent up in a nar∣row space, blows more violently. From the same Cause it is, that a Wind breaking forth from the hollow of Mountains, doth with so much violence storm in the open Air; and that a River, where its Banks are narrow, runs with the greater force and swiftness: For the wind and water being compressed in those more narrow Spaces, do endeavour to deliver themselves from the Force that is upon them.

XV. VVhy Lea∣ther that is extended by force, returns to its former length. Hence it is likewise, that Cloth and Leather that hath been violently stretched out, return to their former Brevity; because many of their pores being straitned by that Extension, cannot suffer the subtil matter to pass through them, without a forceable and violent motion: Wherefore, as soon as the said violent Extension doth cease, the pores return to their former laxity; and the particles that sur∣round the said straitned pores, by means of the subtil matter, are reduced to the bounds of their former Extension.

XVI. VVhy the drawing of ones Finger about the Brim of a Glass, makes the water con∣tained in it to leap up. A wet Finger drawn about the Brim of a Glass full of water, or any other Liquor, first makes the water to wave a little, and to rise up in a small Dew, and being continued, will cause the water to leap over the Brim in great drops.

The Cause whereof is, because by this drawing of the Finger round the Edges of the Glass, the hard, but flexible parts of the Glass are pressed, and consequently the pores straitned, so as that they are no longer able to make way for the Celestial matter to pass through them. But as soon as the Finger is removed to other parts of the brim of the Glass, the subtil matter presently reduceth the pores of the before pressed part to their former wideness: And from this repeated compression of the particles by the Finger, and their Extension by the entring of the subtil matter, there is first caused an agitation of all the parts of the Glass; afterwards a swelling and waving of the Liquor; and lastly, the leaping up of the drops of it over the brim of the Glass.

XVII. The Dila∣tation or Coarctation of the pores of a Body, doth con∣duce to the Elastick force of it. The Coarctation and Dilatation of the Pores of a Body, do much contribute to its Elastick force.

Thus if we wipe the Convex surface of a bent piece of Glass with a hot Cloth, it will by this means become the more bent and crooked. But we shall find the effect contrary, if we wash the Concave surface with Hot-water, or wipe it with a Hot-cloth, for then its Crookedness will be diminished; because the particles of the Fire do dilate the pores of the Glass. This being much the same effect which we find, when having fill'd a Glass Vial with a long and narrow Neck, up to the middle of the Neck with water, we dip the same in Hot-water; whereupon we shall find that the water in the Glass will sink a little; because the heat hath dilated the pores of the Glass, and thereby made the Vial a little wider: But if you let it continue in the Hot-water, then the water which is in the Vial being heated likewise, will rise higher again: But the contrary will happen when you dip the Vial into Cold-water; for the pores of the Glass being straitned by the Cold∣ness of the water, the Liquor in the Glass will rise higher.

XVIII. VVhat is the Reason why Glass Drops, when one end of them is broke off, the whole immedi∣ately breaks into small Dust. Little bits of solid Glass are brought out of Prussia, which are commonly called Glass-drops; the figure of them somewhat resembling a long Olive, with a crooked Neck, not much unlike the Retorts Chymists use, save only that it is solid and without any Cavity, as is exprest in the figure AB. These Glass-drops were formerly made of a hard and thick sort of Glass, but are now made of Crystal-Glass, which being melted, and drawn out of the Melting-Pot with a Glass-Pipe, and being dropt into a Pail of water, becomes formed into these Drops, because of the Clamminess of the Matter. If these Drops be let fall into warm∣water, the Drops will be better and more easily formed. Now it is a very wonderful thing to see a solid piece of Glass, which scarcely can be * 1.8broke with the repeated stroaks of a Hammer, yet when broke off a little above the end or point of it, or being filed in the more distant parts at 1 or 2, doth immediately break into small Dust, to the great admiration of the Spectators. When indeed the end or point of it 3 is broke, it does not always fall into Dust; but if the thicker part of the Neck 4 is broke or snapt off with a pair of Pincers, the whole Drop flies into small Dust, not without some noise.

This notable Effect cannot be assigned to any other Cause, than the subtil matter, which upon the breaking off of the Point 4, doth immediately rush into the pores of it with so much violence, that finding no out-let, it exerts its force upon the Neck of the Drop, and breaks it into the finest Powder. For seeing that this Glass, like a Drop, is at first of an Oval figure, and afterwards pointed, and at first drops into the water in greater quantity, and afterwards in a fine string, the pores that are in the Point of it, must needs be uniform and like one another; whereas those that are in its other parts must be as various, as being more remote from the surface: For the deeper they are in the Glass, the wider they are; and this, because the Point being so thin and slender, is uniformly con∣densed by the water inward and outward, and perforated by the subtil matter; whereas the thicker parts have their outsides cooled and con∣densed, before their inside. The utmost Point therefore 3, may be broken either with a Ham∣mer, or with the Hand, without any pains or wonder; but the other parts 4, or A, cannot be pierced with a Bodkin or File, before that the whole Drop fly into Powder with a great noise: For because of the straitness of the pores that are in the surface of it, and the dilatation of those that are about the middle, the subtil matter rushing vehemently from the middle of the Glass to the outsides of it, dasheth away the partieles of the third Element. For Experience teacheth, that any Glass that is cooled after this manner doth fly to pieces in small particles: For the parts of the Glass that are about the midst of it, being wider, and growing narrower, as they approach to the surface; it must follow that the subtil matter penetrating the more narrow pores, doth dash against them with that violence, that it makes the Glass fly into small Dust.

XIX. A Glass Drop being heated again in the Glass∣makers Furnace, and suffer'd to cool by degrees, doth not, when broke, fly into Dust. But if this Drop be afterwards heated again in the Furnace, and suffer'd to cool by degrees, the now mentioned wonderful effect doth not follow; be∣cause in this case the foresaid Pores are all uniform: According as we find it happens in Steel, which being a second time heated in the Fire, doth thereby acquire uniform pores throughout, still retaining the Hardness it had before. Wherefore also when the Point of it is broke off, there is no reason for its breaking into pieces, because the subtil matter finds its way open through the uni∣form pores of it. But the contrary happens, when being put into the Fire, it be not suffer'd to become red hot; for tho' then when the Point 3 is broke off, or the part 4, it doth not fly into Powder; yet if the breach be made nearer to A, the same effect will follow by the Reason before given.

XX. Pressed Bodies exert a greater force at the begin∣ning of their Dila∣tation, than at the end of it. It is observed, that all Bodies which are dilated by an Elastick virtue, do exert a greater force at the beginning of their Dilatation, than at the end of it.

The Reason is, because these Bodies, at the beginning, are supposed to be more comprest, than afterwards when they are more dilated. Now it is plain, that whilst they are more com∣prest, their Elastick virtue or Spring is so much the stronger, and they do the more endeavour to dilate themselves, so that they must needs exert a greater force at the beginning of their Dilatation, than in the progress of it.

Notes

• * 1.1

  Figure 1.
• * 1.2

  Figure 2
• * 1.3

  Figure 3.
• * 1.4

  Figure 50. in the In∣stitution.
• * 1.5

  Figure 4.
• * 1.6

  Figure 5.
• * 1.7

  Figure 6.
• * 1.8

  Figure 7.