but many Inches below As for what he addes concerning the reason why Water and Quicksilver ascend by suction we have already taught what is to be answered to it by ascribing that ascension to the pressure of the external Air without any need of having recourse to a Funiculus or imagining with him in this place That because nothing besides the Water or Quicksilver can in such cases succeed the Air which yet is not easie to be prov'd in reference to a thin Aethereal substance therefore Partes ipsius aëris to use his expression sic tubo inclusae quae alià s tam facile separantur nunc tam fortiter sibi invicem agglutinentur ut validissimum uti videmus conficiunt catenam qua non solum aqua sed ponderosum illud argentum sic in altum trahatur Which way of wreathing a little rarefied Air into so strong a rope how probable it is I will for a while leave the Reader to judge and advance to our Author's second Notandum which he thus proposes Rarefactionem sive extensionem corporis ad occupandum majorem locum fieri non solo calore sed etiam distensione seu vi divulsivâ sicut è contra condensatio non solo frigore perficitur sed etiam compressione uti innumera passim docent exempla And 't is true and obvious that the Condensation of bodies taking that word in a large sense may be made as well by compression as cold But I wish he had more clearly exprest what he means in this place by that Rarefaction which he sayes is to be made by distension or a vis divulsiva whereof he tells us there are innumerable instances For as far as may be gathered from the three Examples he subjoyns 't is onely the Air that is capable of being so extended as his Hypothesis requires Quicksilver and even Stones must be And I know not how it will be proved that even Air may be thus extended so far as in the Magdeburg Experiment to fill a place more then two thousand times as big as that it fill'd before For that the same Air in this and his two foregoing Instances does adequately fill more space at one time then another he proves but by the rushing in of water into the evacuated Glass and filling it within a little quite full which he sayes is done by the distended Air that contracting it self draws up the water with it Which Explication how much less likely it is then that the water is in such cases impell'd up by the pressure of the Atmosphere we shall anon when we come to discuss his way of Rarefaction and Condensation have occasion to examine In the mean time let us consider with him the Explication which after having premis'd the two above recited Observations he gives us of his Funiculus Cum per primum Notandum argentum ita adhaereat tubi vertici per secundum rarefactio fiat per meram corporis distensionem ita rem se habere ut argentum descendens à vertice tubi affixam ei relinquat superficiem suam extimam sive supremam eamque eousque suo pondere extendat extenuetque donec facilius sit aliam superficiem similiter relinquere quam priorem illam ulterius extendere Secundam igitur relinquit eamque eodem modo descendendo extendit donec facilius sit tertiam adhuc separari quam illam secundam extendere ulterius sic deinceps donec tandem vires amplius non habeat superficies sic separandi extendendi nempe donec perveniat ad altitudinem digitorum duntaxat 29½ ubi quiescit ut capite primo dictum est Thus far our Examiners Explication By which 't is easie to discern that he is fain to assigne his Funiculus a way of being produc'd strange and unparallell'd enough For not to repeat our Animadversions upon the first of the two Notandum's on which the Explication is grounded I must demand by what force upon the bare separation of the Quicksilver and the top of the Tube the new body he mentions comes to be produc'd or at least how it appears that the Mercury leaves any such thing as he speaks of behind it For the sense perceives no such matter at the top of the Tube nor is it necessary to explicate the Phaenomena as we have formerly seen It may also be marvell'd at that the bare weight of the descending Mercury should be able to extend a Surface into a Body And besides it seems precariously affirm'd that there is such a successive leaving behind of one Surface after another as is here imagin'd Nor does it at all appear how though some of the Quicksilver were turn'd into a thin subtile substance yet that substance comes to be contriv'd into a Funiculus of so strange a nature that scarce any weight for ought appears by his Doctrine can be able to break it that contrary to all other strings it may be strâ—â—â—â—ed without being made more slender and that it has other very odde properties some of which we shall anon have occasion to mention As for what our Author subjoynes in these words Eodem itaque fere modo separari videntur hae superficies ab argento descendente in tenuissimum quendam per descendens pondus extendi quo per calorem in accensa candela separantur hujusmodi superficies à subjecta cera aut sevo in subtilissimam flammam extenuantur Ubi not atu dignum quemadmodum flamma illa plusquam millies sine dubio majus spatium occupat quà m antea occupaverat pars illa cerae ex qua conficitur ita prorsus his existimandum Funiculum illum plusquam millies majus spatium occupare quà m prius occupaverat illa argenti particula ex qua sit exortus Uti etiam sine dubio contingit quando talis particula à subjecto igne in vaporem convertitur Though it be the onely Example whereby he endeavours to illustrate the generation of his Funiculus yet I presume he scarce expects we should think it an apposite one For besides that there here intervenes a conspicuous and powerful Agent namely an actual Fire to sever and agitate the parts of the Candle and besides that there is a manifest wasting of the Wax or Tallow turn'd into flame besides these things I say we must not admit that the Fuel when turn'd into a flame does really fill I say not with our Author more then a thousand times but so much as twice more of genuine space then the Wax 't was made of For it may be said that the flame is little or nothing else then an aggregate of those Corpuscles which before lay upon the upper superficies of the Candle and by the violent heat were divided into minuter particles vehemently agitated and brought from lying as it were upon a flat to beat off one another and make up about the Wiek such a figure as is usual in the flame of Candles burning in the free Air.
exhaustion of the Air doth not so ascend of its own accord but is violently drawn or lifted upwards by that rarefied Air contracting it self For as water doth suffer some compression as appears by experience so here also it suffers some distension And hence it is clearly manifest why these bubbles should arise rather from the bottom of the Vessel then from the upper part of the water For when that vehement suction doth endeavour to elevate the water from the bottom of the Vial there arises there a certain subtil matter which being turned into bubbles doth so ascend as is mentioned in the 15. Chapter and the 4. Experiment p. 84. Certum esse c. It is certain that that Opinion is sufficiently refuted by this single Experiment p. 85. Necesse c. It must needs be that that stone could not otherwise descend then by leaving behind it such a thin substance as is left by Quicksilver or Water descending in like manner p. 86. Unde c. Whence I plainly conceive that if two perfectlypolish'd Marbles were so joyned that no Air at all were left between them they could not be drawn asunder by all the power of Man Ibid. Uti etiam c. Which also is confirmed by the Example the Author there brings of a Brass Plate sticking so close to a Marble Table that by a lusty Youth who boasted of his own strength it could not be lifted off by a Ring fixed to its Centre p. 87. Eodem c. Almost the same manner as we see in Cupping-glasses applied to a Patients back in which the flame being extinct the rarefied Air contracting it self doth so vehemently as we see lift up and draw the flesh within the Glass Ibid. In his c. In these three there is nothing occurs to be peculiarly here explicated the account of which is not easie from what is already delivered p. 88. Existimo c. But I think that Whiteness should be rather called a reflex then an innate light because as the Author bears witness it appears not in the dark but onely in the day or by Candle-light Ibid. Verum c. But it seems impossible that such Animals should dye so soon onely for want of a thicker Air. p. 89. Quia per c. Because by the self-contraction of the rarefied Air their breath is drawn out of their bodies p. 90. Atque hinc c. And thence also arose those vehement Convulsions which the Author there mentions certain small Birds to have endured before their death p. 92. In mala c. In a bad Cause they can do no other but who compell'd them to undertake a bad Cause A Summary of the Contents of the several Chapters PART I. WHerein the Adversaries Objections against the Elaterists are examined Chap. 1. The occasion of this Writing pag. 1. Franciscus Linus his civility in writing obliges the Author to the like p. 2. Books concerning the Torrecellian Experiment wherewith the Author was formerly unacquainted ibid. The Inconvenience of Linus's Principles ibid. The division of the ensuing Treatise into three Parts Chap. 2. A repetition of the Adversary's Opinion and Arguments His Arguments against the Weight of the Air examined p. 4. An Experiment of his to prove that the external Air cannot keep up twenty Inches of Quicksilver from descending in a Tube twenty Inches long ibid. The Authors answer and reconciliation of the Experiment to his own Hypothesis p. 5. and the relation of an Experiment of the Authors wherein onely water being employed instead of Quicksilver without other alteration of the Adversaries Experiment it agrees well with and confirms the Authors Hypothesis and his Explication of the mentioned Experiments ibid. That Water hath no Spring at all or a very weak one p. 6. The second Argument examined ibid. Whether the same quantity of Air can adequately fill a greater space p. 7. The conceivableness of both Hypotheses compared ibid. Chap. 3. Another Argument of the Adversaries from an Experiment wherein the Mercury sinking draws the Finger into the Tube examined Q. Whether the Mercury placed in its own station is upheld by the external Air or suspended there by an internal Cord p. 7 8. Chap. 4. A repetition of Franciscus Linus his principal Experiment wherein in a Tube of twenty Inches long the Finger on the top is supposed to be strongly drawn and suck'd into the Tube p. 9. The Experiment explicated without the assistance of Suction by the pressure of the external Air upon the outside of the Finger thrust not suck'd in p. 10. Franciscus Linus his argumentation considered p. 11. Chap. 5. The Examiners last Experiment considered in which he argues against the Authors Hypothesis because Mercury is not suck'd out of a Vessel through a Tube so easily as Water is p. 12 13. An Experiment of Monsieur Paschall shewing that if the upper part of a Tube could be freed from the pressure of all internal Air the Mercury would by the pressure of the outward Air be carried up into the Tube as well as Water till it had attained a height great enough to make its weight equal to that of the Atmosphere p. 14. Why in a more forcible respiration the Mercurial Cylinder is raised higher then in a more languid p. 14 15. A Remark by the bie That the contraction of the Adversaries supposed Funiculus is not felt upon the Lungs p. 15. Chap. 6. The examination of the Adversaries 4. Chapter p. 16. That the Spring of the Air may have some advantage in point of force above the Weight of it p. 17. That it is unintelligible how the same Air can adequately fill more space at one time then at another p. 18. PART II. Wherein the Adversaries Funicular Hypothesis is examined Chap. 1. Wherein what is alledged to prove the Funiculus is considered and some Difficulties are proposed against the Hypothesis The nature of this supposed Funiculus described p. 19. That according to the Adversaries Opinion this Funiculus is produced by Nature onely to hinder a Vacuum p. 20 21. The Adversaries proofs that there is no Vacuum examined p. 21 22. That where no sensible part is un-enlightned the place may not be full of light p. 22. The same true in Odours ibid. That there may be matter enough to transmit the impulse of Light though betwixt the Particles of that matter there should be store of Vacuities intercepted p. 23. That a solid Body hath no considerable sense of pressure from fluid bodies p. 25. Of the causes of the Vibrations of Quicksilver in its descent p. 26 27. Chap. 2. Wherein divers other Difficulties are objected against the Funicular Hypothesis As that in Liquors of divers weights and natures as Water Wine and Quicksilver there should be just the same weight or strength to extend them into a Funiculus p. 27. That whereas the Weight and Spring of the Air is inferr'd from unquestioned Experiments the account of that Hypothesis is strange and unsatisfactory As that the
equal that of between an Inch and an Inch and an halfe only of Quicksilver and consequently the inward Air is far less assisted to dilate it self and surmount the pressure of the outward Air by the Cylinder of Water then by that of Mercury And as for what our Author sayes that if instead of Air Water or some other Liquor be left at the top of the Tube the Quick-silver will not descend the Elaterists can readily solve that Phaenomenon by saying that Water has either no Spring at all or but an exceeding weak one and so scarce presses but by its Weight which in so short a Cylinder is inconsiderable Now the same solution we have given of our Examiners Objection gives us also an account why the Finger is so strongly fastned to the upper part of the Orifice of the Tube it stops for the included Air being so far dilated that an Inch for example left at first in the upper Part of the Tube reaches twice or thrice as far as it did before the descent of the Quick-silver its spring must be proportionably weakned And consequently that part of the Finger that is within the Tube will have much less pressure against it from the dilated Air within then the upper part of the same Finger will have from the unrarefi'd Air without By which means the Pulp of the Finger will be thrust in which our Author is pleas'd to call suckt in as we shall ere long have occasion to declare in our Answer to his second Argument And having said thus much to our Authors first exception against the solution he foresaw we would give of his third Argument we have not much to say at present to his second For whereas he sayes Concipi non posse quomodo aër ille sic se dilatet argentumque deorsum trudat nisi occupando majorem locum Quod tamen hi Autores quam maxime refugiunt asserentes rarefactionem non aliter fieri quam per corpuscula aut vacuitates I wish he had more clearly express'd himself since as his words are couch'd I cannot easily guess what he means and much less easily discern how they make an Argument against his Adversaries For sure he thinks them not so absurd as to imagine that the Air can dilate it self and thrust down the Mercury without in some sense taking up more room then it did before For the very word Dilatation and the effect they ascribe to the included Air clearly imply as much so that I see not why he should say that they are so averse from granting the Air to take up more Place then before especially since he takes notice in the former Chapter that we compare the Expansion of the Air to that of compress'd Wooll and since he here also annexes that we explicate Rarefaction either by Corpuscles or Vacuities But this later Clause makes me suspect his meaning to be that the Elaterists do not admit that the same Air may adequately fil more of Place at one time then at another which I believe to be as true as that the self-same lock of compress'd Wooll has no more Hairs in it nor does adequately fill more Place with them when it is permitted to expand it self then whilest it remain'd compress'd But against this way of Rarefaction our Author here has not any Objection unless it be intimated in these words Concipi non potest Which if it be I shall need only to mind him in this place that whereas many of the chiefest Philosophers both of Ancient and our own times have profest they thought not the Aristotelean way of Rarefaction conceivable and he acknowledges as we shall see anon that it is not clear what the ablest of his Party the modern Plenists are wont to object against the way of Rarefaction he dislikes is that it is not true not that it is not intelligible CHAP. III. OUr Authors Second Objection for so I reckon it is thus propos'd by him Si sumatur tubus utrinque apertus sed longior put a digitorum 40. Argentoque impleatur eique digitus supernè applicetur ut prius videbimus subtracto inferiore digito argentum quidem descendere usque ad consuetam suam stationem Digitum autem superiorem fortiter intra tubum trahi eique firmissime ut prius adhaerere Ex quo rursum evidenter concluditur argentum in sua statione constitutum non ibidem sustentari ab externo aëre sed à funiculo quodam interno suspendi cujus superior éxtremitas digito affixa eum sic intra tubum trahit eique affigit But this Argument being much of the same nature with that drawn from his third Experiment the Answer made to that and to his first may be easily apply'd and will be sufficient for this also especially because in our present case there is less Pressure against the Pulp of the Finger in the inside of the Tube then in the third Experiment where some air is included though much expanded and weakned the Pressure of the Atmosphere being in the present case kept off from it by the subjacent Mercury whereas there is nothing of that Pressure abated against the other parts of the Finger that keep it off from the deserted Cavity of the Tube save only that from the Pulp that is contiguous to the Tube there may be somewhat of that Pressure taken off by the Weight of the Glass it self But as for that Part of the Finger which immediately covers the hole whether or no there be any Spring in its own fibres or other constituent substances which finding no resistance in the place deserted by the Quick silver may contribute to its swelling for that we will not now examine he that has duly consider'd the account already given of this Intrusion of the Pulp into the Glass will find no need of our Authors internal Funiculus which to some seems more difficult to conceive then any of the Phaenomena in Controversie is to be explain'd without it CHAP. IV. BY what we have already said against our Examiners Third Argument we may be assisted to answer his First though he propose it as a very clear Demonstration and though it be indeed the principal thing in his Book Sumatur sayes he tubus brevior digit is 29½ puta digitorum 20. non tamen clausus altero extremo ut hactenus sed utrinque apertus Eic Tubus immerso ejus orificio Argento restagnanti suppesâ—oque digito nâ—effluat Argentum Tubo infundendum impleatur argento vivo aliusque deinde digitus orificio quoque applicetur illudque bene claudat Quo facto si subtrahatur inferior digitus sentietur superior vehementer trahi ac sugi intra tubum tamque pertinaciter ei vel argento potius ut postea adhaerere ut ipsum tubum cum toto argento incluso facilè elevet teneatque in vase pendulum Ex quo sane experimento clarissimè refellitur haec sententia Cum enim juxta eam Argentum in
is a new one flowing from the lucid body that darts its corporeal beams quite through the Glass and Space we dispute about which for want of such Corpuscles were not just before visible And supposing light not to be made by a trajection of Atoms through Diaphanous bodies but a propagation of the impulse of lucid bodies through them yet it will not thence necessarily follow that the deserted part of the Tube must be full As in our 27. Experiment though many of those gross Aerial Particles that appear'd necessary to convey a languid sound were drawn out of our Receiver at the first and second Exsuction yet there remain'd so many of the like Corpuscles that those that were wanting were not miss'd by the sense though afterwards when a far greater number was drawn out they were so there may be matter enough remaining to transmit the impulse of light though betwixt the Particles of that matter there should be store of vacuities intercepted Whereas our Author pretends to prove not onely that there is no coacervate Vacuity in the space so often mentioned but absolutely that there is none For 't is in this last sense as well as the other that the Schools and our Author who defends their Opinion deny a Vacuum But notwithstanding what we have now discours'd as in our 17. Experiment we declin'd determining whether there be a Vacuum or no so now what we have said to the Examiners Argument has not been to declare our whole sense of the Controversie but onely to shew that though his Hypothesis supposes there is no Vacuum yet his Arguments do not sufficiently prove it which may help to shew his Doctrine to be precarious for otherwise the Cartesians though Plenists may plausibly enough whether truly or no I now dispute not decline the necessity of admitting a Vacuum in the deserted space of the Tube by supposing it fill'd with their second and first Element whose Particles they imagine to be minute enough freely to pass in and out through the Pores of Glass But then they must allow the pressure of the outward Air to be the cause of the suspension of the Quicksilver for though the materia coelestis may readily fill the spaces the Mercury deserts yet that within the Tube cannot binder so ponderous a liquor from subsiding as low as the restagnant Mercury since all the parts of the Tube as well the lowermost as the uppermost being pervious to that subtile matter it may with like facility succeed in whatever part of the Tube shall be for saken by the Quicksilver The Examiners second Argument in the same place is That since the Mercurial Cylinder is not sustain'd by the outward Air it must necessarily be that it be kept suspended by his internal string But since for the proof of this he is content to refer us to the third Chapter our having already examin'd that allows us to proceed to his third Argument which is That the Mercurial Cylinder resting in its wonted station does not gravitate as may appear by applying the Finger to the immers'd or lower Orifice of the Tube Whence he infers that it must of necessity be suspended from within the Tube And indeed if you dexterously apply your Finger to the open end of the Tube when you have almost but not quite lifted it out of the restagnant Mercury which circumstance must not be neglected though our Author have omitted it that so you may shut up no more Quicksilver then the Mercurial Cylinder is wont to consist of you will find the Experiment to succeed well enough Which makes me somewhat wonder to find it affirm'd that the learned Maignan denies it not but that you will feel upon your Finger a gravitation or pressure of the Glass-Tube and the contained Mercury as of one body but that you will not feel any sensible pressure of the Mercury apart as if it endeavoured to thrust away your Finger from the Tube But the reason of this is not hard to give in our Hypothesis for according to that the Mercurial Cylinder and the Air counterpoising one another the Finger sustains not any sensibly-differing pressure from the ambient Air that presses against the Nail and sides of it and from the included Quicksilver that presses against the Pulp But if the Mercurial Cylinder should exceed the usual length then the Finger would feel some pressure from that surplusage of Quicksilver which the Air does not assist the Finger to sustain So that this pleasant Phaenomenon may be as well solv'd in our Hypothesis as in the Examiners in which if we had time to clear an Objection which we fore-see might be made but might be answer'd too we would demand why when the Mercury included in the Tube is but of a due altitude it should run out upon the removal of the Finger that stops it beneath in case it be sustain'd onely by the internal Funiculus and do according to his Doctrine when the Funiculus sustains it emulate a solid body if the pressure of the external Air has not as our Author teaches it not to have any thing to do in this matter And if some inquisitive person shall here object That certainly the Finger must feel much pain by being squeez'd betwixt two such pressures as that of a Pillar of thirty Inches of Quick-silver on the one side and an equivalent pressure from the Atmospherical Pillar on the other it may readily be represented that in fluid bodies such as are those concern'd in our Difficulty a solid body has no such sense of pressure from the ambient bodies as unless Experience had otherwise instructed us we should perhaps imagine For not to mention that having inquired of a famous Diver whether he found himself sensibly compressed by the water at the bottom of the Sea he agreed with the generality of Divers in the Negative I am inform'd that the learned Maignan did purposely try that his hand being thrust three or four Palmes deep into Quicksilver his fingers were not sensible either of any weight from the incumbent or of any pressure from the ambient Quicksilver The reason of which whether that inquisitive man have given it or no is not necessary in our present Controversie to be lookt after To these three Arguments the Examiner addes not a fourth unless he design to present it us in this concluding passage Huc etiam faciunt insignes librationes quibus argentum subito descendens agitatur Idem enim hic fit quod in aliis Pendulis ab alto demissis fieri solet But of this Phaenomenon also 't is easie to give an account in our Hypothesis by two several wayes whereof the First which is proper chiefly when the Experiment is made in a close place as our Receiver is That the Quicksilver by its sudden descent acquires an impetus superadded to the pressure it has upon the score of its wonted gravity whereby it for a while falls below its station and thereby
fly back from one another but as we just now said immediately redintegrate themselves Whereas when in the Torricellian Experiment the Tube and contain'd Mercury is suddenly lifted up out of the restagnant Quicksilver into the Air the Funiculus does so strangely contract it self that it quite vanishes insomuch that the ascending Mercury may rise to the very top of the Tube These I say and divers other difficulties might on this occasion be insisted on but that supposing our selves to have mentioned enough of them for once we think it now more seasonable to proceed to the remaining Part of our Discourse CHAP. III. The Aristotelean Rarefaction proposed by the Adversary examin'd BUt this is not all that renders the Examiners Hypothesis improbable For besides those already mentioned particulars upon whose score it is very difficult to be understood it necessarily supposes such a Rarefaction and Condensation as is I confess to me as well as to many other considering persons unintelligible For the better discernment of the force of this Objection we must briefly premise That a body is commonly said to be rarefi'd or dilated for I take the word in a larger sense then I know many others do for a reason that will quickly appear when it acquires greater dimensions then the same body had before and to be condens'd when it is reduc'd into less dimensions that is into a lesser space then it contain'd before as when a dry Spunge being first dipp'd in water swells to a far greater bulk and then being strongly squeez'd and held compressed is not onely reduced into less room then it had before it was squeezed but into less then it had even before it was wetted And I must further premise That Rarefaction as also Condensation being amongst the most obvious Phaenomena of Nature there are three and for ought we know but three wayes of explicating it For either we must say with the Atomists and Vacuists that the Corpuscles whereof the rarefied body consists do so depart from each other that no other substance comes in between them to fill up the deserted spaces that come to be left betwixt the incontiguous Corpuscles or else we must say with divers of the ancient Philosophers and many of the moderns especially the Cartesians that these new Intervals produced betwixt the Particles of the rarefied body are but dilated Pores replenished in like manner as those of the tumid Spunge are by the imbibed water by some subtile Aethereal substance that insinuates it self betwixt the disjoyned Particles or lastly we must imagine with Aristotle and most of his followers that the self-same body does not onely obtain a greater space in Rarefaction and a lesser in Condensation but adequately and exactly fill it and so when rarefied acquires larger dimensions without either leaving any vacuities betwixt its component Corpuscles or admitting between them any new or extraneous substance whatsoever Now 't is to this last and as some call it rigorous way of Rarefaction that our Adversary has recourse in his Hypothesis Though this I confess appear to me so difficult to be conceived that I make a doubt whether any Phaenomenon can be explained by it since to explain a thing is to deduce it from something or other in Nature more known then it self He that would meet with full Discussions of this Aristotelean Rarefaction may resort to the learned writings of Gassendus Cartesius and Maignan who have accused it of divers great absurdities But for my part I shall at present content my self to make use to my purpose of two or three passages that I meet with though not together in our Author himself Let us then suppose that in the Magdeburg Experiment he so often though I think causlesly enough urges to prove his Hypothesis let us I say for easier considerations sake suppose that the undilated Air which as he tells us possessed about half an Inch of space consisted of a hundred Corpuscles or if that name be in this case disliked a hundred parts for it matters not what number we pitch upon and 't will not be denyed but that as the whole parcel of Air or the Aggregate of this hundred Corpuscles is adequate to the whole space it fills so each of the hundred parts that make it up is likewise adequately commensurate to its peculiar space which we here suppose to be a hundredth part of the whole space This premised our Author having elsewhere this passage Corpore occupante locum verbi gratia duplo majorem necesse est ut quaelibet ejus pars locum quoque duplo majorem occupet prompts us to subjoyn that in the whole capacity of the Globe which according to him was two thousand times as great as the room possessed by the unexpanded Air there must likewise be two hundred thousand parts of space commensurate each of them to one of the fore-mentioned hundredth parts of Air and consequently when he affirms that that half Inch of Air possessed the whole cavity of the Globe if we will not admit as he does not either Vacuities or some intervening subtile substance in the Interval of the Aeriall parts he must give us leave to conclude that each part of Air does adequately fill two thousand parts of space Now that this should be resolutely taught to be not onely naturally possible for we dispute not here of what the Divine Omnipotence can do but to be really and regularly done in this Magdeburg Experiment will questionless appear very absurd to the Cartesians and those other Philosophers who take Extension to be but notionally different from Body and consequently impossible to be acquir'd or lost without the addition or detraction of Matter and will I doubt not appear strange to those other Readers who consider how generally Naturalists have looked upon Extension as inseparable and as immediately flowing from matter upon Bodies as having necessary relation to a commensurate space Nor do I see if one portion of Air may so easily be brought exactly to fill up a space two thousand times as big as that which it did but fill before without the addition of any new substance I see not I say why the matter contained in every of these two thousand parts of space may not be further brought to fill two thousand more and so onwards since each of these newly-replen shed spaces is presumed to be exactly filled with Body and no space nor consequently that which the unrarefied Air replenished can be more then adequately full And since according to our Adversary not onely fluid bodies as Air and Quicksilver but even solid and hard ones as Marble are capable of such a Distension as we speak of why may not the World be made I know not how many thousand times bigger then it is without either admitting any thing of Vacuity betwixt its parts or being increased with the addition of one Atome of new matter Which to me is so difficult to conceive that I have sometimes
and hour which height we found to be 29 ¾ Inches Seventhly Our Observations made after this manner furnish'd us with the preceding Table in which there would not probably have been found the difference here set down betwixt the force of the Air when expanded to double its former dimensions and what that force should have been precisely according to the Theory but that the included Inch of Air receiv'd some little accession during the Tryal which this newly-mention'd difference making us suspect we found by replunging the Pipe into the Quicksilver that the included Air had gain'd about half an eighth which we guest to have come from some little aerial bubbles in the Quicksilver contain'd in the Pipe so easie is it in such nice Experiments to miss of exactness We try'd also with 12. Inches of Air shut up to be dilated but being then hindred by some unwelcome avocations to prosecure those Experiments we shall elsewhere out of other Notes and Tryals God permitting set down some other accurate Tables concerning this matter By which possibly we may be assisted to resolve whether the Atmosphere should be look'd upon as it usually is as a limited and bounded Portion of the Air or whether we should in a stricter sense then we did before use the Atmosphere and Aereal part of the World for almost equivalent terms or else whether we should allow the word Atmosphere some other notion in relation to its Extent and Limits for as to its Spring and Weight these Experiments do not question but evince them But we are willing as we said to referre these matters to our Appendix and till then to retain our wonted manner of speaking of the Air and Atmosphere In the mean time to return to our last-mention'd Experiments besides that so little a variation may be in great part imputed to the difficulty of making Experiments of this nature exactly and perhaps a good part of it to something of inequality in the Cavity of the Pipe or even in the thickness of the Glass besides this I say the proportion betwixt the several pressures of the included Air undilated and expanded especially when the Dilatation was great for when the Air swell'd but to four times its first extent the Mercurial Cylinder though of near 23. Inches differ'd not a quarter of an Inch from what it should have been according to Mathematical exactness the proportion I say was sutable enough to what might be expected to allow us to make this reflection upon the whole That whether or no the intimated Theory will hold exactly for about that as I said above I dare determine nothing resolutely till I have further considered the matter yet since the Inch of Air when it was first included was shut up with no other pressure then that which it had from the weight of the incumbent Air and was no more comprest then the rest of the Air we breathed and moved in and since also this Inch of Air when expanded to twice its former dimensions was able with the help of a Mercurial Cylinder of about 15. Inches to counterpoise the weight of the Atmosphere which the weight of the external Air gravitating upon the restagnant Mercury was able to impell up into the Pipe and sustain above twenty eight Inches of Mercury when the internal Air by its great expansion had its Spring too far debilitated to make any considerable I say considerable for it was not yet so dilated as not to make some resistance since I say these things are so the free Air here below appears to be almost as strongly comprest by the weight of the incumbent Air as it would be by the Weight of a Mercurial Cylinder of twenty eight or thirty Inches and consequently is not in such a state of laxity and freedom as men are wont to imagine and acts like some mechanical Agent the decreement of whose force holds a stricter proportion to its increase of dimension then has been hitherto taken notice of I must not now stand to propose the several reflections that may be made upon the foregoing Observations touching the Compression and Expansion of Air partly because we could scarce avoid making the Historical part somewhat prolix and partly because I suppose we have already said enough to shew what was intended namely that to solve the Phaenomena there is not of our Adversaries Hypothesis any need the evincing of which will appear to be of no small moment in our present Controversie to him that considers that the two maine things that induced the Learned Examiner to reject our Hypothesis are that Nature abhors a Vacuum and that though the Air have some Weight Spring yet these are insufficient to make out the known Phaenomena for which we must therefore have recourse to his Funiculus Now as we have formerly seen that he has not so satisfactorily disproved as resolutely rejected a Vacuum so we have now manifested that the Spring of the Air may suffice to perform greater things then what our Explication of the Torricellian Experiments and those of our Engine obliges us to ascribe to it Wherefore since besides the several difficulties that incumber the Hypothesis we oppose and especially its being scarce if at all intelligible we can adde that it is unnecessary we dare expect that such Readers as are not byass'd by their reverence for Aristotle or the Peripatetick Schools will hardly reject an Hypothesis which besides that it is very intelligible is now prov'd to be sufficient only to imbrace a Doctrine that supposes such a rarefaction and condensation as many famous Naturalists rejected for its not being comprehensible even when they knew of no other way that was probable of solving the Phaenomena wont to be explicated by it The III. Part. Wherein what is objected against Mr. Boyle's Explications of particular Experiments is answered AND now we are come to the third and last Part of our Defence wherein we are to consider what our Examiner is pleas'd to object against some passages of our Physicho-Mechanical Treatise But though this may seem the only part wherein I am particularly concern'd yet perhaps we shall find it if not the shortest at least the easiest part of our Task Partly because our Author takes no exceptions at the Experiments themselves as we have recorded them which from an Adversary who in some places speaks of them as an eye-witness is no contemptible testimony that the matters of fact have been rightly delivered and partly because there are divers Experiments which together with their Explications the Examiner has thought fit to leave untoucht and thereby allows us to do so too and partly also because that as to divers of those Experiments upon which he animadverts he does not pretend to shew that our Explications are ill deduc'd or incongruous to our principles but only that the Phaenomena may be explain'd either better or as well by his Hypothesis whereof he supposes himself to have demonstrated the truth together with the