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diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..6833f05 --- /dev/null +++ b/.gitattributes @@ -0,0 +1,3 @@ +* text=auto +*.txt text +*.md text diff --git a/37729-8.txt b/37729-8.txt new file mode 100644 index 0000000..e226c32 --- /dev/null +++ b/37729-8.txt @@ -0,0 +1,4479 @@ +Project Gutenberg's Discourse on Floating Bodies, by Galileo Galilei + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: Discourse on Floating Bodies + +Author: Galileo Galilei + +Translator: Thomas Salusbury + +Release Date: October 12, 2011 [EBook #37729] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK DISCOURSE ON FLOATING BODIES *** + + + + +Produced by Tim Madden and the Online Distributed +Proofreading Team at https://www.pgdp.net (This file was +produced from images generously made available by The +Internet Archive) + + + + + + + [Transcriber's Notes + + All apparent printer's errors retained. Variation in punctuation are + as in the original, but missing full stops at end of paragraphs have + been supplied. There are inconsistencies in the use of italics, + spacing of words and use of full stop after 'AXIOME', abbreviations + etc. All are retained to match text. There is a great variation in + spelling including multiple spellings of the same word, all spelling + has been retained to match text. There are several instances of + obviously missing letters or inverted n & u. These have been changed + or obvious letters replaced, with the changes surrounded by {}. + + All instances are detailed at the end of the text. It should also be + noted that in the original text there is a missing line at the end of + page 24 in original text. + + There are a number of instances in the original text where 'that' is + immediately followed by a second 'that' in the sentence. These could + be potential printer's errors or, since several of them make sense, + part of the author's style. They have been left in the text as they + appear in the original text. + + The original text has many sidenotes, some are true sidenotes, + introductions to paragraphs etc, some acting as footnotes with some + marked in original text with *. These have been dealt with in three + ways with the footnotes placed after their relevant paragraph and + sidenotes place before their relevant paragraph. + + 1) Footnotes marked with capital letter. These were sidenotes in + original text marked with * in the original text and thus acting + like footnotes. + + 2) Footnotes marked with number. These were sidenotes in original + text that were unmarked but acting like normal footnotes. The anchor + in the text was placed at the most suitable relevant place in + comparison with the placement of the sidenote text in the margin, + but still should be considered only an approximate placement. + + 3) Sidenotes placed at start of the relevant paragraph. Some + sidenotes were considered not to be relevant as footnotes, + introductions to paragraphs etc, and were left as sidenotes before + their relevant paragraph.] + + * * * * * + + + + + A + DISCOURSE + _PRESENTED_ + TO THE MOST SERENE + Don Cosimo II. + GREAT DUKE + _OF_ + TUSCANY, + + CONCERNING + + The _NATATION_ of BODIES Vpon, + And _SUBMERSION_ In, + THE + WATER. + + By GALILEUS GALILEI: Philosopher and + Mathematician unto His most Serene Highnesse. + + Englished from the Second Edition of the ITALIAN, + compared with the Manuscript Copies, and reduced + into PROPOSITIONS: + + By _THOMAS SALUSBURY_, Esq; + + _LONDON_: + + Printed by WILLIAM LEYBOURN: + + _M DC LXIII._ + + * * * * * + + [Decoration] + + + + + A DISCOVRSE + + Presented to the Most Serene DON COSIMO II. + + GREAT DUKE of _TUSCANY_: + + CONCERNING + + _The Natation of BODIES Upon, or Submersion_ + _In, the WATER._ + + + + +Considering (Most Serene Prince) that the publishing this present +Treatise, of so different an Argument from that which many expect, and +which according to the intentions I proposed in my [A] Astronomicall +_Adviso_, I should before this time have put forth, might peradventure +make some thinke, either that I had wholly relinquished my farther +imployment about the new Celestiall Observations, or that, at least, I +handled them very remissely; I have judged fit to render an account, +aswell of my deferring that, as of my writing, and publishing this +treatise. + + [A] His Nuncio Siderio. + +As to the first, the last discoveries of _Saturn_ to be +tricorporeall, and of the mutations of Figure in _Venus_, like to +those that are seen in the Moon, together with the Consequents +depending thereupon, have not so much occasioned the demur, as the +investigation of the times of the Conversions of each of the Four +Medicean Planets about _Jupiter_, which I lighted upon in _April_ the +year past, 1611, at my being in _Rome_; where, in the end, I +assertained my selfe, that the first and neerest to _Jupiter_, moved +about 8 _gr._ & 29 _m._ of its Sphere in an houre, makeing its whole +revolution in one naturall day, and 18 hours, and almost an halfe. The +second moves in its Orbe 14 _gr._ 13 _min._ or very neer, in an hour, +and its compleat conversion is consummate in 3 dayes, 13 hours, and +one third, or thereabouts. The third passeth in an hour, 2 _gr._ 6 +_min._ little more or less of its Circle, and measures it all in 7 +dayes, 4 hours, or very neer. The fourth, and more remote than the +rest, goes in one houre, 0 _gr_ 54 _min._ and almost an halfe of its +Sphere, and finisheth it all in 16 dayes, and very neer 18 hours. But +because the excessive velocity of their returns or restitutions, +requires a most scrupulous precisenesse to calculate their places, in +times past and future, especially if the time be for many Moneths or +Years; I am therefore forced, with other Observations, and more exact +than the former, and in times more remote from one another, to correct +the Tables of such Motions, and limit them even to the shortest +moment: for such exactnesse my first Observations suffice not; not +only in regard of the short intervals of Time, but because I had not +as then found out a way to measure the distances between the said +Planets by any Instrument: I Observed such Intervals with simple +relation to the Diameter of the Body of _Jupiter_; taken, as we have +said, by the eye, the which, though they admit not errors of above a +Minute, yet they suffice not for the determination of the exact +greatness of the Spheres of those Stars. But now that I have hit upon +a way of taking such measures without failing, scarce in a very few +Seconds, I will continue the observation to the very occultation of +_JUPITER_, which shall serve to bring us to the perfect knowledge of +the Motions, and Magnitudes of the Orbes of the said Planets, together +also with some other consequences thence arising. I adde to these +things the observation of some obscure Spots[1], which are discovered in +the Solar Body, which changing, position in that, propounds to our +consideration a great argument either that the Sun revolves in it +selfe, or that perhaps other Starrs, in like manner as _Venus_ and +_Mercury_, revolve about it, invisible in other times, by reason of +their small digressions, lesse than that of _Mercury_, and only +visible when they interpose between the Sun and our eye, or else hint +the truth of both this and that; the certainty of which things ought +not to be contemned, nor omitted. + + [1] The Authors Observations of the Solar Spots + + _Continuall observation hath at last assured me that these Spots + are matters contiguous to the Body of the Sun, there continually + produced in great number, and afterwards dissolved, some in a + shorter, some in a longer time, and to be by the Conversion or + Revolution of the Sun in it selfe, which in a Lunar Moneth, or + thereabouts, finisheth its Period, caried about in a Circle, an + accident great of it selfe, and greater for its Consequences._ + +As to the other particular in the next place [B] Many causes have +moved me to write the present Tract, the subject whereof, is the +Dispute which I held some dayes since, with some learned men of this +City, about which, as your Highnesse knows, have followed many +Discourses: The principall of which Causes hath been the Intimation of +your Highnesse, having commended to me Writing, as a singular means to +make true known from false, reall from apparent Reasons, farr better +than by Disputing vocally, where the one or the other, or very often +both the Disputants, through too greate heate, or exalting of the +voyce, either are not understood, or else being transported by +ostentation of not yeilding to one another, farr from the first +Proposition, with the novelty, of the various Proposals, confound both +themselves and their Auditors. + + [B] The occasion inducing the Author to write this Treatise. + +Moreover, it seemed to me convenient to informe your Highnesse of all +the sequell, concerning the Controversie of which I treat, as it hath +been advertised often already by others: and because the Doctrine +which I follow, in the discussion of the point in hand, is different +from that of _Aristotle_; and interferes with his Principles, I have +considered that against the Authority of that most famous Man, which +amongst many makes all suspected that comes not from the Schooles of +the Peripateticks, its farr better to give ones Reasons by the Pen +than by word of mouth, and therfore I resolved to write the present +discourse: in which yet I hope to demonstrate that it was not out of +capritiousnesse, or for that I had not read or understood _Aristotle_, +that I sometimes swerve from his opinion, but because severall Reasons +perswade me to it, and the same _Aristotle_ hath tought me to fix my +judgment on that which is grounded upon Reason, and not on the bare +Authority of the Master[2]; and it is most certaine according to the +sentence of _Alcinoos_, that philosophating should be free. Nor is the +resolution of our Question in my judgment without some benefit to the +Universall[3], forasmuch as treating whether the figure of Solids +operates, or not, in their going, or not going to the bottome in +Water, in occurrences of building Bridges or other Fabricks on the +Water, which happen commonly in affairs of grand import, it may be of +great availe to know the truth. + + [2] _Aristotle_ prefers Reason to the Authority ofan Author. + + [3] The benefit of this Argument. + +I say therfore, that being the last Summer in company with certain +Learned men, it was said in the argumentation; That Condensation was +the propriety of Cold[4], and there was alledged for instance, the +example of Ice: now I at that time said, that, in my judgment, the Ice +should be rather Water rarified than condensed[5], and my reason was, +because Condensation begets diminution of Mass, and augmentation of +gravity, and Rarifaction causeth greater Lightness, and augmentarion +of Masse: and Water in freezing, encreaseth in Masse, and the Ice made +thereby is lighter than the Water on which it swimmeth. + + [4] Condensation the Propriety of Cold, according to the + Peripateticks. + + [5] Ice rather water rarified, than condensed, and why: + + _What I say, is manifest, because, the medium subtracting from the + whole Gravity of Sollids the weight of such another Masse of the + said Medium; as_ Archimedes _proves in his_ [C] First Booke De + Insidentibus Humido; _when ever the Masse of the said Solid + encreaseth by Distraction, the more shall the_ Medium _detract from + its entire Gravity; and lesse, when by Compression it shall be + condensed and reduced to a lesse Masse._ + + [C] In lib: 1. of Natation of Bodies Prop. 7. + + [Sidenote: Figure operates not in the Natation of Sollids.] + +It was answered me, tha{t} that proceeded not from the greater Levity, +but from the Figure, large and flat, which not being able to penetrate +the Resistance of the Water, is the cause that it submergeth not. I +replied, that any piece of Ice, of whatsoever Figure, swims upon the +Water, a manifest signe, that its being never so flat and broad, hath +not any part in its floating: and added, that it was a manifest proofe +hereof to see a piece of Ice of very broad Figure being thrust to the +botome of the Water, suddenly return to flote atoppe, which had it +been more grave, and had its swimming proceeded from its Forme, unable +to penetrate the Resistance of the _Medium_, that would be altogether +impossible; I concluded therefore, that the Figure was in sort a Cause +of the Natation or Submersion of Bodies, but the greater or lesse +Gravity in respect of the Water: and therefore all Bodyes heavier than +it of what Figure soever they be, indifferently go to the bottome, and +the lighter, though of any figure, float indifferently on the top: and +I suppose that those which hold otherwise, were induced to that +beliefe, by seeing how that diversity of Formes or Figures, greatly +altereth the Velosity, and Tardity of Motion; so that Bodies of Figure +broad and thin, descend far more leasurely into the Water, than those +of a more compacted Figure, though both made of the same Matter: by +which some might be induced to believe that the Dilatation of the +Figure might reduce it to such amplenesse that it should not only +retard but wholly impede and take away the Motion, which I hold to be +false. Upon this Conclusion, in many dayes discourse, was spoken much, +and many things, and divers Experiments produced, of which your +Highnesse heard, and saw some, and in this discourse shall have all +that which hath been produced against my Assertion, and what hath been +suggested to my thoughts on this matter, and for confirmation of my +Conclusion: which if it shall suffice to remove that (as I esteem +hitherto false) Opinion, I shall thinke I have not unprofitably spent +my paynes and time. and although that come not to passe, yet ought I +to promise another benefit to my selfe, namely, of attaining the +knowledge of the truth, by hearing my Fallacyes confuted, and true +demonstrations produced by those of the contrary opinion. + +And to proceed with the greatest plainness and perspicuity that I can +possible, it is, I conceive, necessary, first of all to declare what +is the true, intrinsecall, and totall Cause, of the ascending of some +Sollid Bodyes in the Water, and therein floating; or on the contrary, +of their sinking and so much the rather in asmuch as I cannot satisfie +myselfe in that which _Aristotle_ hath left written on this Subject. + + [Sidenote: The cause of the Natation & submersion of Solids in + the Water.] + +I say then the Cause why some Sollid Bodyes descend to the Bottom of +Water, is the excesse of their Gravity, above the Gravity of the +Water; and on the contrary, the excess of the Waters Gravity above the +Gravity of those, is the Cause that others do not descend, rather that +they rise from the Bottom, and ascend to the Surface. This was +subtilly demonstrated by _Archimedes_ in his Book Of the NATATION of +BODIES: Conferred afterwards by a very grave Author, but, if I erre +not invisibly, as below for defence of him, I shall endeavour to +prove. + +I, with a different Method, and by other meanes, will endeavour to +demonstrate the same, reducing the Causes of such Effects to more +intrinsecall and immediate Principles, in which also are discovered +the Causes of some admirable and almost incredible Accidents, as that +would be, that a very little quantity of Water, should be able, with +its small weight, to raise and sustain a Solid Body, an hundred or a +thousand times heavier than it. + +And because demonstrative Order so requires, I shall define certain +Termes, and afterwards explain some Propositions, of which, as of +things true and obvious, I may make use of to my present purpose. + + + + +DEFINITION I. + + _I then call equally Grave_ in specie, _those Matters of which equall + Masses weigh equally._ + + +As if for example, two Balls, one of Wax, and the other of some Wood +of equall Masse, were also equall in Weight, we say, that such Wood, +and the Wax are _in specie_ equally grave. + + + + +DEFINITION II. + + _But equally grave in Absolute Gravity, we call two Sollids, + weighing equally, though of Mass they be unequall._ + + +As for example, a Mass of Lead, and another of Wood, that weigh each +ten pounds, I call equall in Absolute Gravity, though the Mass of the +Wood be much greater then that of the Lead. + +_And, consequently, less Grave_ in specie. + + + + +DEFINITION III. + + _I call a Matter more Grave_ in specie _than another, of which a + Mass, equall to a Mass of the other, shall weigh more._ + + +And so I say, that Lead is more grave _in specie_ than Tinn, because +if you take of them two equall Masses, that of the Lead weigheth more. + + + + +DEFINITION IV. + + _But I call that Body more grave absolutely than this, if that + weigh more than this, without any respect had to the Masses._ + + +And thus a great piece of Wood is said to weigh more than a little +lump of Lead, though the Lead be _in specie_ more heavy than the Wood. +And the same is to be understood of the less grave _in specie_, and +the less grave absolutely. + +These Termes defined, I take from the Mechanicks two Principles: the +first is, that + + + + +AXIOME. I. + + _Weights absolutely equall, moved with equall Velocity, are of + equall Force and Moment in their operations._ + + + + +_DEFINITION V._ + + Moment, amongst Mechanicians, signifieth that Vertue, that Force, + or that Efficacy, with which the Mover moves, and the Moveable + resists. + + + _Which Vertue dependes not only on the simple Gravity, but on the + Velocity of the Motion, and on the diverse Inclinations of the + Spaces along which the Motion is made: For a descending Weight + makes a greater Impetus in a Space much declining, than in one less + declining; and in summe, what ever is the occasion of such Vertue, + it ever retaines the name of Moment; nor in my Judgement, is this + sence new in our Idiome, for, if I mistake not, I think we often + say; This is a weighty businesse, but the other is of small moment: + and we consider lighter matters and let pass those of Moment; a + Metaphor, I suppose, taken from the Mechanicks._ + +As for example, two weights equall in absolute Gravity, being put +into a Ballance of equall Arms, they stand in _Equilibrium_, neither +one going down, nor the other up: because the equality of the +Distances of both, from the Centre on which the Ballance is supported, +and about which it moves, causeth that those weights, the said +Ballance moving, shall in the same Time move equall Spaces, that is, +shall move with equall Velocity, so that there is no reason for which +this Weight should descend more than that, or that more than this; and +therefore they make an _Equilibrium_, and their Moments continue of +semblable and equall Vertue. + +The second Principle is; That + + + + +AXIOME II. + + _The Moment and Force of the Gravity, is encreased by the Velocity + of the Motion._ + + +So that Weights absolutely equall, but conjoyned with Velocity +unequall, are of Force, Moment and Vertue unequall: and the more +potent, the more swift, according to the proportion of the Velocity of +the one, to the Velocity of the other. Of this we have a very +pertinent example in the Balance or Stiliard of unequall Arms, at +which Weights absolutely equall being suspended, they do not weigh +down, and gravitate equally, but that which is at a greater distance +from the Centre, about which the Beam moves, descends, raising the +other, and the Motion of this which ascends is slow, and the other +swift: and such is the Force and Vertue, which from the Velocity of +the Mover, is conferred on the Moveable, which receives it, that it +can exquisitely compensate, as much more Weight added to the other +slower Moveable: so that if of the Arms of the Balance, one were ten +times as long as the other, whereupon in the Beames moving about the +Centre, the end of that would go ten times as far as the end of this, +a Weight suspended at the greater distance, may sustain and poyse +another ten times more grave absolutely than it: and that because the +Stiliard moving, the lesser Weight shall move ten times faster than +the bigger. It ought alwayes therefore to be understood, that Motions +are according to the same Inclinations, namely, that if one of the +Moveables move perpendicularly to the Horizon, then the other makes +its Motion by the like Perpendicular; and if the Motion of one were to +be made Horizontally; that then the other is made along the same +Horizontall plain: and in summe, alwayes both in like Inclinations. +This proportion between the Gravity and Velocity is found in all +Mechanicall Instruments: and is considered by _Aristotle_, as a +Principle in his _Mechanicall Questions_; whereupon we also may take +it for a true Assumption, That + + + + +AXIOME III. + + _Weights absolutely unequall, do alternately counterpoyse and + become of equall Moments, as oft as their Gravities, with + contrary proportion, answer to the Velocity of their Motions._ + + +That is to say, that by how much the one is less grave than the other, +by so much is it in a constitution of moving more swiftly than that. + +Having prefatically explicated these things, we may begin to enquire, +what Bodyes those are which totally submerge in Water, and go to the +Bottom, and which those that by constraint float on the top, so that +being thrust by violence under Water, they return to swim, with one +part of their Mass visible above the Surface of the Water: and this we +will do by considering the respective operation of the said Solids, +and of Water: Which operation followes the Submersion and sinking; and +this it is[6], That in the Submersion that the Solid maketh, being +depressed downwards by its proper Gravity, it comes to drive away the +water from the place where it successively subenters, and the water +repulsed riseth and ascends above its first levell, to which Ascent on +the other side it, as being a grave Body of its own nature, resists: +And because the descending Solid more and more immerging, greater and +greater quantity of Water ascends, till the whole Sollid be submerged; +its necessary to compare the Moments of the Resistance of the water to +Ascension, with the Moments of the pressive Gravity of the Solid: And +if the Moments of the Resistance of the water, shall equalize the +Moments of the Solid, before its totall Immersion[7]; in this case +doubtless there shall be made an _Equilibrium_, nor shall the Body +sink any farther. But if the Moment of the Solid, shall alwayes exceed +the Moments wherewith the repulsed water successively makes +Resistance[8], that Solid shall not only wholly submerge under water, but +shall descend to the Bottom. But if, lastly, in the instant of totall +Submersion, the equality shall be made between the Moments of the +prement Solid, and the resisting Water[9]; then shall rest, ensue, and +the said Solid shall be able to rest indifferently, in whatsoever part +of the water. By this time is manifest the necessity of comparing the +Gravity of the water, and of the Solid[10]; and this comparison might at +first sight seem sufficient to conclude and determine which are the +Solids that float a-top, and which those that sink to the Bottom in +the water, asserting that those shall float which are lesse grave _in +specie_ than the water, and those submerge, which are _in specie_ more +grave. For it seems in appearance, that the Sollid in sinking +continually, raiseth so much Water in Mass, as answers to the parts of +its own Bulk submerged: whereupon it is impossible, that a Solid less +grave _in specie_, than water, should wholly sink, as being unable to +raise a weight greater than its own, and such would a Mass of water +equall to its own Mass be. And likewise it seems necessary, that the +graver Solids do go to the Bottom, as being of a Force more than +sufficient for the raising a Masse of water, equall to its own, though +inferiour in weight. Nevertheless the business succeeds otherwise: and +though the Conclusions are true, yet are the Causes thus assigned +deficient, nor is it true, that the Solid in submerging, raiseth and +repulseth Masses of Water, equall to the parts of it self submerged; +but the Water repulsed, is alwayes less than the parts of the Solid +submerged[11]: and so much the more by how much the Vessell in which the +Water is contained is narrower: in such manner that it hinders not, +but that a Solid may submerge all under Water, without raising so much +Water in Mass, as would equall the tenth or twentieth part of its own +Bulk: like as on the contrary, a very small quantity of Water, may +raise a very great Solid Mass[12], though such Solid should weigh +absolutely a hundred times as much, or more, than the said Water, if +so be that the Matter of that same Solid be _in specie_ less grave +than the Water. And thus a great Beam, as suppose of a 1000 weight, +may be raised and born afloat by Water, which weighs not 50: and this +happens when the Moment of the Water is compensated by the Velocity of +its Motion. + + [6] How the submersion of Solids in the Water, is effected. + + [7] What Solids shall float on the Water. + + [8] What Solids shall sinke to the botome. + + [9] What Solids shall rest in all places of the Water. + + [10] The Gravitie of the Water and Solid must be compared in all + Problems, of Natation of Bodies. + + [11] The water repelled is ever less than the parts of the Sollid + submerged. + + [12] _A_ small quantity of water, may float a very great Solid + Mass. + +But because such things, propounded thus in abstract, are somewhat +difficult to be comprehended, it would be good to demonstrate them by +particular examples; and for facility of demonstration, we will +suppose the Vessels in which we are to put the Water, and place the +Solids, to be inviron'd and included with sides erected perpendicular +to the Plane of the Horizon, and the Solid that is to be put into such +vessell to be either a streight Cylinder, or else an upright Prisme. + +_The which proposed and declared, I proceed to demonstrate the truth +of what hath been hinted, forming the ensuing Theoreme._ + + + + +_THEOREME I._ + + [Sidenote: The Proportion of the water raised to the Solid + submerged.] + + The Mass of the Water which ascends in the submerging of a Solid, + Prisme or Cylinder, or that abaseth in taking it out, is less + than the Mass of the said Solid, so depressed or advanced: and + hath to it the same proportion, that the Surface of the Water + circumfusing the Solid, hath to the same circumfused Surface, + together with the Base of the Solid. + + +_Let the Vessell be A B C D, and in it the Water raised up to the +Levell E F G, before the Solid Prisme H I K be therein immerged; but +after that it is depressed under Water, let the Water be raised as +high as the Levell L M, the Solid H I K shall then be all under Water, +and the Mass of the elevated Water shall be L G, which is less than +the Masse of the Solid depressed, namely of H I K, being equall to the +only part E I K, which is contained under the first Levell E F G. +Which is manifest, because if the Solid H I K be taken out, the Water +I G shall return into the place occupied by the Mass E I K, where it +was continuate before the submersion of the Prisme. And the Mass L G +being equall to the Mass E K: adde thereto the Mass E N, and it shall +be the whole Mass E M, composed of the parts of the Prisme E N, and of +the Water N F, equall to the whole Solid H I K: And, therefore, the +Mass L G shall have the same proportion to E M, as to the Mass H I K: +But the Mass L G hath the same proportion to the Mass E M, as the +Surface L M hath to the Surface M H: Therefore it is manifest, that +the Mass of Water repulsed L G, is in proportion to the Mass of the +Solid submerged H I K; as the Surface L M, namely, that of the Water +ambient about the Sollid, to the whole Surface H M, compounded of the +said ambient water, and the Base of the Prisme H N. But if we suppose +the first Levell of the Water the according to the Surface H M, and +the Prisme allready submerged H I K; and after to be taken out and +raised to E A O, and the Water to be faln from the first Levell H L M +as low as E F G; It is manifest, that the Prisme E A O being the same +with H I K, its superiour part H O, shall be equall to the inferiour E +I K: and remove the common part E N, and, consequently, the Mass of +the Water L G is equall to the Mass H O; and, therefore, less than the +Solid, which is without the Water, namely, the whole Prisme E A O, to +which likewise, the said Mass of Water abated L G, hath the same +proportion, that the Surface of the Waters circumfused L M hath to the +same circumfused Surface, together with the Base of the Prisme A O: +which hath the same demonstration with the former case above._ + +[Illustration] + +_And from hence is inferred, that the Mass of the Water, that riseth +in the immersion of the Solid, or that ebbeth in elevating it, is not +equall to all the Mass of the Solid, which is submerged or elevated, +but to that part only, which in the immersion is under the first +Levell of the Water, and in the elevation remaines above the first +Levell: Which is that which was to be demonstrated. We will now pursue +the things that remain._ + +And first we will demonstrate that, + + + + +THEOREME II. + + [Sidenote: The proportion of the water abated, to the Solid + raised.] + + _When in one of the above said Vessels, of what ever breadth, + whether wide or narrow, there is placed such a Prisme or + Cylinder, inviron'd with Water, if we elevate that Solid + perpendicularly, the Water circumfused shall abate, and the + Abatement of the Water, shall have the same proportion to the + Elevation of the Prisme, as one of the Bases of the Prisme, hath + to the Surface of the Water Circumfused._ + + +[Illustration] + +Imagine in the Vessell, as is aforesaid, the Prisme A C D B to be +placed, and in the rest of the Space the Water to be diffused as far +as the Levell E A: and raising the Solid, let it be transferred to G +M, and let the Water be abased from E A to N O: I say, that the +descent of the Water, measured by the Line A O, hath the same +proportion to the rise of the Prisme, measured by the Line G A, as the +Base of the Solid G H hath to the Surface of the Water N O. The which +is manifest: because the Mass of the Solid G A B H, raised above the +first Levell E A B, is equall to the Mass of Water that is abased E N +O A. Therefore, E N O A and G A B H are two equall Prismes; for of +equall Prismes, the Bases answer contrarily to their heights: +Therefore, as the Altitude A O is to the Altitude A G, so is the +Superficies or Base G H to the Surface of the Water N O. If therefore, +for example, a Pillar were erected in a waste Pond full of Water, or +else in a Well, capable of little more then the Mass of the said +Pillar, in elevating the said Pillar, and taking it out of the Water, +according as it riseth, the Water that invirons it will gradually +abate, and the abasement of the Water at the instant of lifting out +the Pillar, shall have the same proportion, that the thickness of the +Pillar hath to the excess of the breadth of the said Pond or Well, +above the thickness of the said Pillar: so that if the breadth of the +Well were an eighth part larger than the thickness of the Pillar, and +the breadth of the Pond twenty five times as great as the said +thickness, in the Pillars ascending one foot, the water in the Well +shall descend seven foot, and that in the Pond only 1/25 of a foot. + + [Sidenote: Why a Solid less grave _in specie_ than water, stayeth + not under water, in very small depths:] + +This Demonstrated, it will not be difficult to show the true cause, +how it comes to pass, that, + + + + +THEOREME III. + + _A Prisme or regular Cylinder, of a substance specifically less + grave than Water, if it should be totally submerged in Water, + stayes not underneath, but riseth, though the Water circumfused + be very little, and in absolute Gravity, never so much inferiour + to the Gravity of the said Prisme._ + + +Let then the Prisme A E F B, be put into the Vessell C D F B, the same +being less grave _in specie_ than the Water: and let the Water infused +rise to the height of the Prisme: I say, that the Prisme left at +liberty, it shall rise, being born up by the Water circumfused C D E +A. For the Water C E being specifically more grave than the Solid A F, +the absolute weight of the water C E, shall have greater proportion to +the absolute weight of the Prisme A F, than the Mass C E hath to the +Mass A F (in regard the Mass hath the same proportion to the Mass, +that the weight absolute hath to the weight absolute, in case the +Masses are of the same Gravity _in specie_.) But the Mass C E is to +the Mass A F, as the Surface of the water A C, is to the Superficies, +or Base of the Prisme A B; which is the same proportion as the ascent +of the Prisme when it riseth, hath to the descent of the Water +circumfused C E. + +[Illustration] + +Therefore, the absolute Gravity of the water C E, hath greater +proportion to the absolute Gravity of the Prisme A F; than the Ascent +of the Prisme A F, hath to the descent of the said water C E. The +Moment, therefore, compounded of the absolute Gravity of the water C +E, and of the Velocity of its descent, whilst it forceably repulseth +and raiseth the Solid A F, is greater than the Moment compounded of +the absolute Gravity of the Prisme A F, and of the Tardity of its +ascent, with which Moment it contrasts and resists the repulse and +violence done it by the Moment of the water: Therefore, the Prisme +shall be raised. + + [Sidenote: The Proportion according to which the Submersion & + Natation of Solids is made.] + +It followes, now, that we proceed forward to demonstrate more +particularly, how much such Solids shall be inferiour in Gravity to +the water elevated; namely, what part of them shall rest submerged, +and what shall be visible above the Surface of the water: but first it +is necessary to demonstrate the subsequent Lemma. + + + + +LEMMA I. + + [Sidenote: The absolute Gravity of Solids, are in a proportion + compounded of their Specifick Gravities, and of their Masses.] + + _The absolute Gravities of Solids, have a proportion compounded of + the proportions of their specificall Gravities, and of their + Masses._ + + +[Illustration] + +Let A and B be two Solids. I say, that the Absolute Gravity of A, +hath to the Absolute Gravity of B, a proportion compounded of the +proportions of the specificall Gravity of A, to the Specificall +Gravity of B, and of the Mass A to the Mass B. Let the Line D have the +same proportion to E, that the specifick Gravity of A, hath to the +specifick Gravity of B; and let E be to F, as the Mass A to the Mass +B: It is manifest, that the proportion of D to F, is compounded of the +proportions D and E; and E and F. It is requisite, therefore, to +demonstrate, that as D is to F, so the absolute Gravity of A, is to +the absolute Gravity of B. Take the Solid C, equall in Mass to the +Solid A, and of the same Gravity _in specie_ with the Solid B. +Because, therefore, A and C are equall in Mass, the absolute Gravity +of A, shall have to the absolute Gravity of C, the same proportion, as +the specificall Gravity of A, hath to the specificall Gravity of C, or +of B, which is the same _in specie_; that is, as D is to E. And, +because, C and B are of the same Gravity _in specie_, it shall be, +that as the absolute weight of C, is to the absolute weight of B, so +the Mass C, or the Mass A, is to the Mass B; that is, as the Line E to +the Line F. As therefore, the absolute Gravity of A, is to the +absolute Gravity of C, so is the Line D to the Line E: and, as the +absolute Gravity of C, is to the absolute Gravity of B, so is the Line +E to the Line F: Therefore, by Equality of proportion, the absolute +Gravity of A, is to the absolute Gravity of B, as the Line D to the +Line F: which was to be demonstrated. I proceed now to demonstrate, +how that, + + + + +THEOREME IV. + + [Sidenote: The proportion of water requisite to make a Solid + swim:] + + _If a Solid, Cylinder, or Prisme, lesse grave specifically than the + Water, being put into a Vessel, as above, of whatsoever + greatnesse, and the Water, be afterwards infused, the Solid shall + rest in the bottom, unraised, till the Water arrive to that part + of the Altitude, of the said Prisme, to which its whole Altitude + hath the same proportion, that the Specificall Gravity of the + Water, hath to the Specificall Gravity of the said Solid: but + infusing more Water, the Solid shall ascend._ + + +[Illustration] + +Let the Vessell be M L G N of any bigness, and let there be placed in +it the Solid Prisme D F G E, less grave _in specie_ than the water; +and look what proportion the Specificall Gravity of the water, hath to +that of the Prisme, such let the Altitude D F, have to the Altitude F +B. I say, that infusing water to the Altitude F B, the Solid D G shall +not float, but shall stand in _Equilibrium_, so, that that every +little quantity of water, that is infused, shall raise it. Let the +water, therefore, be infused to the Levell A B C; and; because the +Specifick Gravity of the Solid D G, is to the Specifick Gravity of the +water, as the altitude B F is to the altitude F D; that is, as the +Mass B G to the Mass G D; as the proportion of the Mass B G is to the +Mass G D, as the proportion of the Mass G D is to the Mass A F, they +compose the Proportion of the Mass B G to the Mass A F. Therefore, the +Mass B G is to the Mass A F, in a proportion compounded of the +proportions of the Specifick Gravity of the Solid G D, to the +Specifick Gravity of the water, and of the Mass G D to the Mass A F: +But the same proportions of the Specifick Gravity of G D, to the +Specifick Gravity of the water, and of the Mass G D to the Mass A F, +do also by the precedent _Lemma_, compound the proportion of the +absolute Gravity of the Solid D G, to the absolute Gravity of the Mass +of the water A F: Therefore, as the Mass B G is to the Mass A F, so is +the Absolute Gravity of the Solid D G, to the Absolute Gravity of the +Mass of the water A F. But as the Mass B G is to the Mass A F; so is +the Base of the Prisme D E, to the Surface of the water A B; and so is +the descent of the water A B, to the Elevation of the Prisme D G; +Therefore, the descent of the water is to the elevation of the Prisme, +as the absolute Gravity of the Prisme, is to the absolute Gravity of +the water: Therefore, the Moment resulting from the absolute Gravity +of the water A F, and the Velocity of the Motion of declination, with +which Moment it forceth the Prisme D G, to rise and ascend, is equall +to the Moment that results from the absolute Gravity of the Prisme D +G, and from the Velocity of the Motion, wherewith being raised, it +would ascend: with which Moment it resists its being raised: because, +therefore, such Moments are equall, there shall be an _Equilibrium_ +between the water and the Solid. And, it is manifest, that putting a +little more water unto the other A F, it will increase the Gravity and +Moment, whereupon the Prisme D G, shall be overcome, and elevated till +that the only part B F remaines submerged. Which is that that was to +be demonstrated. + + +COROLLARY I. + + [Sidenote: _H_ow far Solids less grave _in specie_ than water, do + submerge.] + + _By what hath been demonstrated, it is manifest, that Solids less + grave_ in specie _than the water, submerge only so far, that as + much water in Mass, as is the part of the Solid submerged, doth + weigh absolutely as much as the whole Solid._ + +For, it being supposed, that the Specificall Gravity of the water, is +to the Specificall Gravity of the Prisme D G, as the Altitude D F, is +to the Altitude F B; that is, as the Solid D G is to the Solid B G; we +might easily demonstrate, that as much water in Mass as is equall to +the Solid B G, doth weigh absolutely as much as the whole Solid D G; +For, by the _Lemma_ foregoing, the Absolute Gravity of a Mass of +water, equall to the Mass B G, hath to the Absolute Gravity of the +Prisme D G, a proportion compounded of the proportions, of the Mass B +G to the Mass G D, and of the Specifick Gravit{y} of the water, to the +Specifick Gravity of the Prisme: But the Gravity _in specie_ of the +water, to the Gravity _in specie_ of the Prisme, is supposed to be as +the Mass G D to the Mass G B. Therefore, the Absolute Gravity of a +Mass of water, equall to the Mass B G, is to the Absolute Gravity of +the Solid D G, in a proportion compounded of the proportions, of the +Mass B G to the Mass G D, and of the Mass D G to the Mass G B; which +is a proportion of equalitie. The Absolute Gravity, therefore, of a +Mass of Water equall to the part of the Mass of the Prisme B G, is +equall to the Absolute Gravity of the whole Solid D G. + + +COROLLARY II. + + [Sidenote: _A_ Rule to equilibrate Solids in the water.] + + _It followes, moreover, that a Solid less grave than the water, + being put into a Vessell of any imaginable greatness, and water + being circumfused about it to such a height, that as much water + in Mass, as is the part of the Solid submerged, do weigh + absolutely as much as the whole Solid; it shall by that water be + justly sustained, be the circumfused Water in quantity greater or + lesser._ + +[Illustration] + +For, if the Cylinder or Prisme M, less grave than the water, _v. gra._ +in Subsequiteriall proportion, shall be put into the capacious Vessell +A B C D, and the water raised about it, to three quarters of its +height, namely, to its Levell A D: it shall be sustained and exactly +poysed in _Equilibrium_. The same will happen; if the Vessell E N S F +were very small, so, that between the Vessell and the Solid M, there +were but a very narrow space, and only capable of so much water, as +the hundredth part of the Mass M, by which it should be likewise +raised and erected, as before it had been elevated to three fourths of +the height of the Solid: which to many at the first sight, may seem a +notable Paradox, and beget a conceit, that the Demonstration of these +effects, were sophisticall and fallacious: but, for those who so +repute it, the Experiment is a means that may fully satisfie them. But +he that shall but comprehend of what Importance Velocity of Motion is, +and how it exactly compensates the defect and want of Gravity, will +cease to wonder, in considering that at the elevation of the Solid M, +the great Mass of water A B C D abateth very little, but the little +Mass of water E N S F decreaseth very much, and in an instant, as the +Solid M before did rise, howbeit for a very short space: Whereupon the +Moment, compounded of the small Absolute Gravity of the water E N S F, +and of its great Velocity in ebbing, equalizeth the Force and and +Moment, that results from the composition of the immense Gravity of +the water A B C D, with its great slownesse of ebbing; since that in +the Elevation of the Sollid M, the abasement of the lesser water E S, +is performed just so much more swiftly than the great Mass of water A +C, as this is more in Mass than that which we thus demonstrate. + + [Sidenote: _T_he proportion according to which water riseth and + falls in different Vessels at the Immersion and Elevation of + Solids.] + +In the rising of the Solid M, its elevation hath the same proportion +to the circumfused water E N S F, that the Surface of the said water, +hath to the Superficies or Base of the said Solid M; which Base hath +the same proportion to the Surface of the water A D, that the +abasement or ebbing of the water A C, hath to the rise or elevation of +the said Solid M. Therefore, by Perturbation of proportion, in the +ascent of the said Solid M, the abasement of the water A B C D, to the +abasement of the water E N S F, hath the same proportion, that the +Surface of the water E F, hath to the Surface of the water A D; that +is, that the whole Mass of the water E N S F, hath to the whole Mass A +B C D, being equally high: It is manifest, therefore, that in the +expulsion and elevation of the Solid M, the water E N S F shall exceed +in Velocity of _M_otion the water A B C D, asmuch as it on the other +side is exceeded by that in quantity: whereupon their Moments in such +operations, are mutually equall. + +[Illustration] + + _And, for ampler confirmation, and clearer explication of this, let + us consider the present Figure, (which if I be not deceived, may + serve to detect the errors of some Practick Mechanitians who upon a + false foundation some times attempt impossible enterprizes,) in + which, unto the large Vessell E I D F, the narrow Funnell or Pipe I + C A B is continued, and suppose water infused into them, unto the + Levell L G H, which water shall rest in this position, not without + admiration in some, who cannot conceive how it can be, that the + heavie charge of the great Mass of water G D, pressing downwards, + should not elevate and repulse the little quantity of the other, + contained in the Funnell or Pipe C L, by which the descent of it is + resisted and hindered: But such wonder shall cease, if we begin to + suppose the water G D to be abased only to Q D, and shall + afterwards consider, what the water C L hath done, which to give + place to the other, which is descended from the Levell G H, to the + Levell Q O, shall of necessity have ascended in the same time, from + the Levell L unto A B. And the ascent L B, shall be so much greater + than the descent G Q, by how much the breadth of the Vessell G D, + is greater than that of the Funnell I C; which, in summe, is as + much as the water G D, is more than the water L C: but in regard + that the Moment of the Velocity of the Motion, in one Moveable, + compensates that of the Gravity of another what wonder is it, if + the swift ascent of the lesser Water C L, shall resist the slow + descent of the greater G D?_ + +The same, therefore, happens in this operation, as in rhe Stilliard, +in which a weight of two pounds counterpoyseth an other of 200, +asoften as that shall move in the same time, a space 100 times greater +than this: which falleth out when one Arme of the Beam is an hundred +times as long as the other. Let the erroneous opinion of those +therefore cease, who hold that a Ship is better, and easier born up in +a great abundance of water, then in a lesser quantity[13], (_this was +believed by_ Aristotle _in his Problems, Sect. 23, Probl. 2._) it being +on the contrary true, that its possible, that a Ship may as well float +in ten Tun of water, as in an Ocean. + + [13] A ship flotes as well in ten Tun of Water as in an Ocean. + + [Sidenote: A Solid specifiaclly graver than the water, cannot be + born up by any quantity of it.] + +But following our matter, I say, that by what hath been hitherto +demonstrated, we may understand how, that + + +COROLLARY III. + + _One of the above named Solids, when more grave_ in specie _than the + water, can never be sustained, by any whatever quantity of it._ + +For having seen how that the Moment wherewith such a Solid, as grave +_in specie_ as the water, contrasts with the Moment of any Mass of +water whatsoever, is able to retain it, even to its totall Submersion, +without its ever ascending; it remaineth, manifest, that the water is +far less able to raise it up, when it exceeds the same _in specie_: +so, that though you infuse water till its totall Submersion, it shall +still stay at the Bottome, and with such Gravity, and Resistance to +Elevation, as is the excess of its Absolute Gravity, above the +Absolute Gravity of a Mass equall to it, made of water, or of a Matter +_in specie_ equally grave with the water: and, though you should +moreover adde never so much water above the Levell of that which +equalizeth the Altitude of the Solid, it shall not, for all that, +encrease the Pression, or Gravitation, of the parts circumfused about +the said Solid, by which greater pression, it might come to be +repulsed; because, the Resistance is not made, but only by those parts +of the water, which at the Motion of the said Solid do also move, and +these are those only, which are comprehended by the two Superficies +equidistant to the Horizon, and their parallels, that comprehend the +Altitude of the Solid immerged in the water. + +I conceive, I have by this time sufficiently declared and opened the +way to the contemplation of the true, intrinsecall and proper Causes +of diverse Motions, and of the Rest of many Solid Bodies in diverse +_Mediums_, and particularly in the water, shewing how all in effect, +depend on the mutuall excesses of the Gravity of the Moveables and of +the _Mediums_: and, that which did highly import, removing the +Objection, which peradventure would have begotten much doubting, and +scruple in some, about the verity of my Conclusion, namely, how that +notwithstanding, that the excess of the Gravity of the water, above +the Gravity of the Solid, demitted into it, be the cause of its +floating and rising from the Bottom to the Surface, yet a quantity of +water, that weighs not ten pounds, can raise a Solid that weighs above +100 pounds: in that we have demonstrated, That it sufficeth, that such +difference be found between the Specificall Gravities of the _Mediums_ +and Moveables, let the particular and absolute Gravities be what they +will: insomuch, that a Solid, provided that it be Specifically less +grave than the water, although its absolute weight were 1000 pounds, +yet may it be born up and elevated by ten pounds of water, and less: +and on the contrary, another Solid, so that it be Specifically more +grave than the water, though in absolute Gravity it were not above a +pound, yet all the water in the Sea, cannot raise it from the Bottom, +or float it. This sufficeth me, for my present occasion, to have, by +the above declared Examples, discovered and demonstrated, without +extending such matters farther, and, as I might have done, into a long +Treatise: yea, but that there was a necessity of resolving the above +proposed doubt, I should have contented my self with that only, which +is demonstrated by _Archimedes_, in his first _Book De Insidentibus +humido_[14]: where in generall termes he infers and confirms the same +Conclusions, namely, that Solids (_a_) less grave than water, swim or +float upon it, the (_b_) more grave go to the Bottom, and the (_c_) +equally grave rest indifferently in all places, yea, though they +should be wholly under water. + + [14] _Of Natation_ (a) _Lib. 1, Prop. 4._ (b) _Id. Lib. 1. Prop. + 3._ (c) _Id. Lib. 1. Prop. 3._ + + [Sidenote: The Authors defence of _Archimedes_ his Doctrine, + against the oppositions of _Buonamico_.] + +But, because that this Doctrine of Archimedes, perused, transcribed +and examined by _Signor Francesco Buonamico_, in his _fifth Book of +Motion, Chap. 29_, and afterwards by him confuted, might by the +Authority of so renowned, and famous a Philosopher, be rendered +dubious, and suspected of falsity; I have judged it necessary to +defend it, if I am able so to do, and to clear _Archimedes_, from +those censures, with which he appeareth to be charged. _Buonamico_ +rejecteth the Doctrine of _Archimedes_, first[15], as not consentaneous +with the Opinion of _Aristotle_, adding, that it was a strange thing +to him, that the Water should exceed the Earth in Gravity[16], seeing on +the contrary, that the Gravity of water, increaseth, by means of the +participation of Earth. And he subjoyns presently after[17], that he was +not satisfied with the Reasons of _Archimedes_, as not being able with +that Doctrine, to assign the cause whence it comes, that a Boat and a +Vessell, which otherwise, floats above the water, doth sink to the +Bottom, if once it be filled with water; that by reason of the +equality of Gravity, between the water within it, and the other water +without, it should stay a top; but yet, nevertheless, we see it to go +to the Bottom. + + [15] His first Objection against the Doctrine of _Archimedes_. + + [16] His Second Objection. + + [17] His third Objection. + +He farther addes[18], that _Aristotle_ had clearly confuted the Ancients, +who said, that light Bodies moved upwards[19], driven by the impulse of +the more grave Ambient: which if it were so, it should seem of +necessity to follow, that all naturall Bodies are by nature heavy, and +none light: For that the same would befall the Fire and Air, if put in +the Bottom of the water. And, howbeit, _Aristotle_ grants a Pulsion in +the Elements, by which the Earth is reduced into a Sphericall Figure, +yet nevertheless, in his judgement; it is not such that it can remove +grave Bodies from their naturall places, but rather, that it send them +toward the Centre, to which (as he somewhat obscurely continues to +say,) the water principally moves, if it in the interim meet not with +something that resists it, and, by its Gravity, thrusts it out of its +place: in which case, if it cannot directly, yet at least as well as +it can, it tends to the Centre: but it happens, that light Bodies by +such Impulsion, do all ascend upward: but this properly they have by +nature, as also, that other of swimming. He concludes, lastly[20], that he +concurs with _Archimedes_ in his Conclusions; but not in the Causes, +which he would referre to the facile and difficult Separation of the +_Medium_, and to the predominance of the Elements, so that when the +Moveable superates the power of the _Medium_; as for example, Lead +doth the Continuity of water, it shall move thorow it, else not. + + [18] His fourth Objection. + + [19] The _A_ncients denyed _A_bsolute Levity. + + [20] The causes of Natation & Submersion, according to the + Peripateticks. + +This is all that I have been able to collect, as produced against +_Archimedes_ by _Signor Buonamico_: who hath not well observed the +Principles and Suppositions of _Archimedes_; which yet must be false, +if the Doctrine be false, which depends upon them; but is contented to +alledge therein some Inconveniences, and some Repugnances to the +Doctrine and Opinion of _Aristotle_. In answer to which Objections, I +say, first[21], That the being of _Archimedes_ Doctrine, simply different +from the Doctrine of _Aristotle_, ought not to move any to suspect it, +there being no cause, why the Authority of this should be preferred to +the Authority of the other: but, because, where the decrees of Nature +are indifferently exposed to the intellectuall eyes of each, the +Authority of the one and the other, loseth all a{u}thenticalness of +Perswasion, the absolute power residing in Reason; therefore I pass to +that which he alledgeth in the second place[22], as an absurd consequent +of the Doctrine of _Archimedes_, namely, That water should be more +grave than Earth. But I really find not, that ever _Archimedes_ said +such a thing, or that it can be rationally deduced from his +Conclusions: and if that were manifest unto me, I verily believe, I +should renounce his Doctrine, as most erroneous. Perhaps this +Deduction of _Buonamico_, is founded upon that which he citeth of the +Vessel, which swims as long as its voyd of water, but once full it +sinks to the Bottom, and understanding it of a Vessel of Earth, he +infers against _Archimedes_ thus: Thou sayst that the Solids which +swim, are less grave than water: this Vessell swimmeth: therefore, +this Vessell is lesse grave than water. If this be the Illation. I +easily answer, granting that this Vessell is lesse grave than water, +and denying the other consequence, namely, that Earth is less Grave +than Water. The Vessel that swims occupieth in the water, not only a +place equall to the Mass of the Earth, of which it is formed; but +equall to the Earth and to the Air together, contained in its +concavity. And, if such a Mass compounded of Earth and Air, shall be +less grave than such another quantity of water, it shall swim, and +shall accord with the Doctrine of _Archimedes_; but if, again, +removing the Air, the Vessell shall be filled with water, so that the +Solid put in the water, be nothing but Earth, nor occupieth other +place, than that which is only possest by Earth, it shall then go to +the Bottom, by reason that the Earth is heavier than the water: and +this corresponds well with the meaning of _Archimedes_. See the same +effect illustrated, with such another Experiment, In pressing a Viall +Glass to the Bottom of the water, when it is full of Air, it will meet +with great resistance, because it is not the Glass alone, that is +pressed under water, but together with the Glass a great Mass of Air, +and such, that if you should take as much water, as the Mass of the +Glass, and of the Air contained in it, you would have a weight much +greater than that of the Viall, and of its Air: and, therefore, it +will not submerge without great violence: but if we demit only the +Glass into the water, which shall be when you shall fill the Glass +with water, then shall the Glass descend to the Bottom; as superiour +in Gravity to the water. + + [21] The Authors answer to the first Objection. + + [22] The Authors answer to the second Objection. + +Returning, therefore, to our first purpose; I say, that Earth is more +grave than water, and that therefore, a Solid of Earth goeth to the +bottom of it; but one may possibly make a composition of Earth and +Air, which shall be less grave than a like Mass of Water; and this +shall swim: and yet both this and the other experiment shall very well +accord with the Doctrine of _Archimedes_. But because that in my +judgment it hath nothing of difficulty in it, I will not positively +affirme that _Signor Buonamico_, would by such a discourse object unto +_Archimedes_ the absurdity of inferring by his doctrine, that Earth +was less grave than Water, though I know not how to conceive what +other accident he could have induced thence. + +Perhaps such a Probleme (in my judgement false) was read by _Signor +Buonamico_ in some other Author, by whom peradventure it was +attributed as a singular propertie, of some particular Water, and so +comes now to be used with a double errour in confutation of +_Archimedes_, since he saith no such thing, nor by him that did say it +was it meant of the common Element of Water. + + [Sidenote: The Authors answer to the third Objection.] + +The third difficulty in the doctrine of _Archimedes_ was, that he +could not render a reason whence it arose, that a piece of Wood, and a +Vessell of Wood, which otherwise floats, goeth to the bottom, if +filled with Water. _Signor Buonamico_ hath supposed that a Vessell of +Wood, and of Wood that by nature swims, as before is said, goes to the +bottom, if it be filled with water; of which he in the following +Chapter, which is the 30 of the fifth Book copiously discourseth: but +I (speaking alwayes without diminution of his singular Learning) dare +in defence of _Archimedes_ deny this experiment, being certain that a +piece of Wood which by its nature sinks not in Water, shall not sinke +though it be turned and converted into the forme of any Vessell +whatsoever, and then filled with Water: and he that would readily see +the Experiment in some other tractable Matter, and that is easily +reduced into several Figures, may take pure Wax, and making it first +into a Ball or other solid Figure, let him adde to it so much Lead as +shall just carry it to the bottome, so that being a graine less it +could not be able to sinke it, and making it afterwards into the forme +of a Dish, and filling it with Water, he shall finde that without the +said Lead it shall not sinke, and that with the Lead it shall descend +with much slowness: & in short he shall satisfie himself, that the +Water included makes no alteration. I say not all this while, but that +its possible of Wood to make Barkes, which being filled with water, +sinke; but that proceeds not through its Gravity, encreased by the +Water, but rather from the Nailes and other Iron Workes, so that it no +longer hath a Body less grave than Water, but one mixt of Iron and +Wood, more grave than a like Masse of Water. Therefore let _Signor +Buonamico_ desist from desiring a reason of an effect, that is not in +nature: yea if the sinking of the Woodden Vessell when its full of +Water, may call in question the Doctrine of _Archimedes_, which he +would not have you to follow, is on the contrary consonant and +agreeable to the Doctrine of the Peripateticks, since it aptly +assignes a reason why such a Vessell must, when its full of Water, +descend to the bottom; converting the Argument the other way, we may +with safety say that the Doctrine of _Archimedes_ is true, since it +aptly agreeth with true experiments, and question the other, whose +Deductions are fastened upon erroneouss Conclusions. As for the other +point hinted in this same Instance, where it seemes that _Benonamico_ +understands the same not only of a piece of wood, shaped in the forme +of a Vessell, but also of massie Wood, which filled, _scilicet_, as I +believe, he would say, soaked and steeped in Water, goes finally to +the bottom that happens in some porose Woods, which, while their +Porosity is replenished with Air, or other Matter less grave than +Water, are Masses specificially less grave than the said Water, like +as is that Viall of Glass whilest it is full of Air: but when, such +light Matter departing, there succeedeth Water into the same +Porosities and Cavities, there results a compound of Water and Glass +more grave than a like Mass of Water: but the excess of its Gravity +consists in the Matter of the Glass, and not in the Water, which +cannot be graver than it self: so that which remaines of the Wood, the +Air of its Cavities departing, if it shall be more grave _in specie_ +than Water, fil but its Porosities with Water, and you shall have a +Compost of Water and of Wood more grave than Water, but not by vertue +of the Water received into and imbibed by the Porosities, but of that +Matter of the Wood which remains when the Air is departed: and being +such it shall, according to the Doctrine of _Archimedes_, goe to the +bottom, like as before, according to the same Doctrine it did swim. + + [Sidenote: The Authors answer to the fourth Objection.] + +As to that finally which presents itself in the fourth place, +namely, that the _Ancients_ have been heretofore confuted by +_Aristotle_, who denying Positive and Absolute Levity, and truely +esteeming all Bodies to be grave, said, that that which moved upward +was driven by the circumambient Air, and therefore that also the +Doctrine of _Archimedes_, as an adherent to such an Opinion was +convicted and confuted: I answer first, that _Signor Buonamico_ in my +judgement hath imposed upon _Archimedes_, and deduced from his words +more than ever he intended by them, or may from his Propositions be +collected, in regard that _Archimedes_ neither denies, nor admitteth +Positive Levity, nor doth he so much as mention it: so that much less +ought _Buonamico_ to inferre, that he hath denyed that it might be the +Cause and Principle of the Ascension of Fire, and other Light Bodies[23]: +having but only demonstrated, that Solid Bodies more grave than Water +descend in it, according to the excess of their Gravity above the +Gravity of that, he demonstrates likewise, how the less grave ascend +in the same Water[24], accordng to its excess of Gravity, above the +Gravity of them. So that the most that can be gathered from the +Demonstration of _Archimedes_ is, that like as the excess of the +Gravity of the Moveable above the Gravity of the Water, is the Cause +that it descends therein, so the excess of the Gravity of the water +above that of the Moveable, is a sufficient Cause why it descends not, +but rather betakes it self to swim: not enquiring whether of moving +upwards there is, or is not any other Cause contrary to Gravity: nor +doth _Archimedes_ discourse less properly than if one should say: If +the South Winde shall assault the Barke with greater _Impetus_ than is +the violence with which the Streame of the River carries it towards +the South, the motion of it shall be towards the North: but if the +_Impetus_ of the Water shall overcome that of the Winde, its motion +shall be towards the South. The discourse is excellent and would be +unworthily contradicted by such as should oppose it, saying: Thou +mis-alledgest as Cause of the motion of the Bark towards the South, +the _Impetus_ of the Stream of the Water above that of the South +Winde; mis-alledgest I say, for it is the Force of the North Winde +opposite to the South, that is able to drive the Bark towards the +South. Such an Objection would be superfluous, because he which +alledgeth for Cause of the Motion the Stream of the Water, denies not +but that the Winde opposite to the South may do the same, but only +affirmeth that the force of the Water prevailing over the South Wind, +the Bark shall move towards the South: and saith no more than is true. +And just thus when _Archimedes_ saith, that the Gravity of the Water +prevailing over that by which the moveable descends to the Bottom, +such moveable shall be raised from the Bottom to the Surface alledgeth +a very true Cause of such an Accident, nor doth he affirm or deny that +there is, or is not, a vertue contrary to Gravity, called by some +Levity, that hath also a power of moving some Matters upwards. Let +therefore the Weapons of _Signor Buonamico_ be directed against +_Plato_[25], and other _Ancients_, who totally denying _Levity_, and +taking all Bodies to be grave, say that the Motion upwards is made, +not from an intrinsecal Principle of the Moveable, but only by the +Impulse of the _Medium_; and let _Archimedes_ and his Doctrine escape +him, since he hath given him no Cause of quarelling with him. But if +this Apologie, produced in defence of _Archimedes_, should seem to +some insufficient to free him from the Objections and Arguments, +produced by _Aristotle_ against _Plato_, and the other _Ancients_, as if +they did also fight against _Archimedes_, alledging the Impulse of the +Water as the Cause of the swimming of some Bodies less grave than it[26], +I would not question, but that I should be able to maintaine the +Doctrine of _Plato_ and those others to be most true, who absolutely +deny Levity, and affirm no other Intrinsecal Principle of Motion to be +in Elementary Bodies save only that towards the Centre of the Earth[27], +nor no other Cause of moving upwards, speaking of that which hath the +resemblance of natural Motion, but only the repulse of the _Medium_, +fluid, and exceeding the Gravity of the Moveable[28]: and as to the +Reasons of _Aristotle_ on the contrary, I believe that I could be able +fully to answer them, and I would assay to do it, if it were +absolutely necessary to the present Matter, or were it not too long a +Digression for this short Treatise. I will only say, that if there +were in some of our Ellementary Bodies an Intrinsecall Principle and +Naturall Inclination to shun the Centre of the Earth, and to move +towards the Concave of the Moon, such Bodies, without doubt, would +more swiftly ascend through those _Mediums_ that least oppose the +Velocity of the Moveable, and these are the more tenuous and subtle; +as is, for example, the Air in comparison of the Water, we daily +proving that we can with farre more expeditious Velocity move a Hand +or a Board to and again in one than in the other[29]: nevertheless, we +never could finde any Body, that did not ascend much more swiftly in +the water than in the Air. Yea of Bodies which we see continually to +ascend in the Water, there is none that having arrived to the confines +of the Air, do not wholly lose their Motion[30]; even the Air it self, +which rising with great Celerity through the Water, being once come to +its Region it loseth all + + [23] Of Natation, Lib. 1. Prop. 7. + + [24] Of Natation, Lib. 1. Prop. 4. + + [25] _Plato_ denyeth Positive Levity. + + [26] The Authors defence of the doctrine of _Plato_ and the + _Ancients_, who absolutely deny Levity: + + [27] According to _Plato_ there is no Principle of the Motion, of + descent in Naturall Bodies, save that to the Centre. + + [28] No cause of the motion of Ascent, save the Impulse of the + _Medium_, exceeding the Moveable in Gravitie. + + [29] Bodies ascend much swifter in the Water, than in the Air. + + [30] All Bodies ascending through Water, lose their Motion, + comming to the confines of the Air. + + [Sidenote: The lighter Bodies ascend more swiftly through Water.] + +And, howbeit, Experience shewes, that the Bodies, successively less +grave, do most expeditiously ascend in water, it cannot be doubted, +but that the Ignean Exhalations do ascend more swiftly through the +water, than doth the Air: which Air is seen by Experience to ascend +more swiftly through the Water, than the Fiery Exhalations through the +Air[31]: Therefore, we must of necessity conclude, that the said +Exhalations do much more expeditiously ascend through the Water, than +through the Air; and that, consequently, they are moved by the Impulse +of the Ambient _Medium_, and not by an intrinsick Principle that is in +them, of avoiding the Centre of the Earth; to which other grave Bodies +tend. + + [31] Fiery Exhalations ascend thorow the Water more swiftly than + doth the Air; & the Air ascends more swiftly thorow the Water, + than Fire thorow the Air. + + [Sidenote: _T_he Authors confutation of the Peripateticks Causes + of Natation & Submersion.] + +To that which for a finall conclusion, _Signor Buonamico_ produceth +of going about to reduce the descending or not descending, to the +easie and uneasie Division of the _Medium_, and to the predominancy of +the Elements: I answer, as to the first part, that that cannot in any +manner be admitted as a Cause, being that in none of the Fluid +_Mediums_, as the Air, the Water, and other Liquids, there is any +Resistance against Division[32], but all by every the least Force, are +divided and penetrated, as I will anon demonstrate: so, that of such +Resistance of Division there can be no Act, since it self is not in +being. As to the other part, I say, that the predominancy of the +Elements in Moveables[33], is to be considered, as far as to the excesse +or defect of Gravity, in relation to the _Medium_: for in that Action, +the Elements operate not, but only, so far as they are grave or light: +therefore, to say that the Wood of the Firre sinks not, because Air +predominateth in it, is no more than to say, because it is less grave +than the Water. Yea, even the immediate Cause, is its being less grave +than the Water[34]: and it being under the predominancy of the Air, is the +Cause of its less Gravity: Therefore, he that alledgeth the +predominancy of the Element for a Cause, brings the Cause of the +Cause, and not the neerest and immediate Cause. Now, who knows not +that the true Cause is the immediate, and not the mediate[35]? Moreover, +he that alledgeth Gravity, brings a Cause most perspicuous to Sence[36]: +The cause we may very easily assertain our selves; whether Ebony, for +example, and Firre, be more or less grave than water: but whether +Earth or Air predominates in them, who shall make that manifest? +Certainly, no Experiment can better do it than to observe whether they +swim or sink. So, that he who knows, not whether such a Solid swims, +unless when he knows that Air predominates in it, knows not whether it +swim, unless he sees it swim, for then he knows that it swims, when he +knows that it is Air that predominates, but knows not that Air hath +the predominance, unless he sees it swim: therefore, he knows not if +it swims, till such time as he hath seen it swim. + + [32] Water & other fluids void of Resistance against Division. + + [33] _T_he predominancy of Elements in Moveables to be considered + only in relation to their excess or defect of Gravity in reference + to the _Medium_. + + [34] _T_he immediate Cause of Natation is that the Moveable is + less grave than the Water. + + [35] _T_he Peripateticks alledge for the reason of Natation the + Cause of the Cause. + + [36] Gravity a Cause most perspicuous to sence. + +Let us not then despise those Hints, though very dark, which Reason, +after some contemplation, offereth to our Intelligence, and lets be +content to be taught by _Archimedes_, that then any Body shall +submerge in water[37], when it shall be specifically more grave than it, +and that if it shall be less grave[38], it shall of necessity swim, and +that it will rest indifferently in any place under water, if its +Gravity be perfectly like to that of the water. + + [37] Lib 1. of Natation Prop. 7 + + [38] Id. Lib. 1. Prop. 4. + +These things explained and proved[39], I come to consider that which +offers it self, touching what the Diversity of figure given unto the +said Moveable hath to do with these Motions and Rests; and proceed to +affirme, that, + + [39] Id. Lib 1. Prop. 3. + + + + +THEOREME V. + + [Sidenote: Diversity of Figure no Cause of its absolute Natation + or Submersion.] + + _The diversity of Figures given to this or that Solid, cannot any + way be a Cause of its absolute Sinking or Swimming._ + + +So that if a Solid being formed, for example, into a Sphericall +Figure, doth sink or swim in the water, I say, that being formed into +any other Figure, the same figure in the same water, shall sink or +swim: nor can such its Motion by the Expansion or by other mutation of +Figure, be impeded or taken away. + + [Sidenote: The Expansion of Figure, retards the Velocity of the + ascent or descent of the Moveable in the water; but doth not + deprive it of all Motion.] + +The Expansion of the Figure may indeed retard its Velocity, aswell of +ascent as descent, and more and more according as the said Figure is +reduced to a greater breadth and thinness: but that it may be reduced +to such a form as that that same matter be wholly hindred from moving +in the same water, that I hold to be impossible. In this I have met +with great contradictors, who producing some Experiments, and in +perticular a thin Board of Ebony, and a Ball of the same Wood, and +shewing how the Ball in Water descended to the bottom, and the Board +being put lightly upon the Water submerged not, but rested; have held, +and with the Authority of _Aristotle_, confirmed themselves in their +Opinions, that the Cause of that Rest was the breadth of the Figure, +u{n}able by its small weight to pierce and penetrate the Resistance of +the Waters Crassitude, which Resistance is readily overcome by the +other Sphericall Figure. + +This is the Principal point in the present Question, in which I +perswade my self to be on the right side. + +Therefore, beginning to investigate with the examination of exquisite +Experiments that really the Figure doth not a jot alter the descent or +Ascent of the same Solids, and having already demonstrated that the +greater or less Gravity of the Solid in relation to the Gravity of the +_Medium_ is the cause of Descent or Ascent: when ever we would make +proof of that, which about this Effect the diversity of Figure +worketh, its necessary to make the Experiment with Matter wherein +variety of Gravities hath no place. For making use of Matters which +may be different in their Specifical Gravities, and meeting with +varieties of effects of Ascending and Descending, we shall alwayes be +left unsatisfied whether that diversity derive it self really from the +sole Figure, or else from the divers Gravity also. We may remedy this +by takeing one only Matter, that is tractable and easily reduceable +into every sort of Figure. Moreover, it will be an excellent expedient +to take a kinde of Matter, exactly alike in Gravity unto the Water: +for that Matter, as far as pertaines to the Gravity, is indifferent +either to Ascend or Descend; so that we may presently observe any the +least difference that derives it self from the diversity of Figure. + + [Sidenote: An Experiment in Wax, that proveth Figure to have no + Operation in Natation & Submersion.] + +Now to do this, Wax is most apt, which, besides its incapacity of +receiveing any sensible alteration from its imbibing of Water, is +ductile or pliant, and the same piece is easily reduceable into all +Figures: and being _in Specie_ a very inconsiderable matter inferiour +in Gravity to the Water, by mixing therewith a little of the fileings +of Lead it is reduced to a Gravity exactly equall to that of the +Water. + +This Matter prepared, and, for example, a Ball being made thereof as +bigge as an Orange or biger, and that made so grave as to sink to the +bottom, but so lightly, that takeing thence one only Grain of Lead, it +returns to the top, and being added, it submergeth to the bottom, let +the same Wax afterwards be made into a very broad and thin Flake or +Cake; and then, returning to make the same Experiment, you shall see +that it being put to the bottom, it shall, with the Grain of Lead rest +below, and that Grain deducted, it shall ascend to the very Surface, +and added again it shall dive to the bottom. And this same effect +shall happen alwaies in all sort of Figures, as wel regular as +irregular: nor shall you ever finde any that will swim without the +removall of the Grain of Lead, or sinke to the bottom unless it be +added: and, in short, about the going or not going to the Bottom, you +shall discover no diversity, although, indeed, you shall about the +quick and slow descent: for the more expatiated and distended Figures +move more slowly aswel in the diveing to the bottom as in the rising +to the top; and the other more contracted and compact Figures, more +speedily. Now I know not what may be expected from the diversity of +Figures, if the most contrary to one another operate not so much as +doth a very small Grain of Lead, added or removed. + +Me thinkes I hear some of the Adversaries to raise a doubt upon my +produced Experiment[40]. And first that they offer to my consideration, +that the Figure, as a Figure simply, and disjunct from the Matter +workes not any effect, but requires to be conjoyned with the Matter; +and, furthermore, not with every Matter, but with those only, +wherewith it may be able to execute the desired operation. Like as we +see it verified by Experience, that the Acute and sharp Angle is more +apt to cut, than the Obtuse; yet alwaies provided, that both the one +and the other, be joyned with a Matter apt to cut, as for example, +with Steel. Therefore, a Knife with a fine and sharp edge, cuts Bread +or Wood with much ease, which it will not do, if the edge be blunt and +thick: but he that will instead of Steel, take Wax, and mould it into +a Knife, undoubtedly shall never know the effects of sharp and blunt +edges: because neither of them will cut, the Wax being unable by +reason of its flexibility, to overcome the hardness of the Wood and +Bread. And, therefore, applying the like discourse to our purpose, +they say, that the difference of Figure will shew different effects, +touching Natation and Submersion, but not conjoyned with any kind of +Matter, but only with those Matters which, by their Gravity, are apt +to resist the Velocity of the water, whence he that would elect for +the Matter, Cork or other light wood, unable, through its Levity, to +superate the Crassitude of the water, and of that Matter should forme +Solids of divers Figures, would in vain seek to find out what +operation Figure hath in Natation or Submersion; because all would +swim, and that not through any property of this or that Figure, but +through the debility of the Matter, wanting so much Gravity, as is +requisite to superate and overcome the Density and Crassitude of the +water. + + [40] An objection against the Experiment in Water. + +Its needfull, therefore, if wee would see the effect wrought by the +Diversity of Figure, first to make choice of a Matter of its nature +apt to penetrate the Crassitude of the water. And, for this effect[41], +they have made choice of such a Matter, as fit, that being readily +reduced into Sphericall Figure, goes to the Bottom; and it is Ebony, +of which they afterwards making a small Board or Splinter, as thin as +a Lath, have illustrated how that this, put upon the Surface of the +water, rests there without descending to the Bottom: and making, on +the otherside, of the same wood a Ball, no less than a hazell Nut, +they shew, that this swims not, but descendes. From which Experiment, +they think they may frankly conclude, that the Breadth of the Figure +in the flat Lath or Board, is the cause of its not descending to the +Bottom, for as much as a Ball of the same Matter, not different from +the Board in any thing but in Figure, submergeth in the same water to +the Bottom. The discourse and the Experiment hath really so much of +probability and likelyhood of truth in it, that it would be no wonder, +if many perswaded by a certain cursory observation, should yield +credit to it; nevertheless, I think I am able to discover, how that it +is not free from falacy. + + [41] An Experiment in Ebany, brought to disprove the Experiment + in Wax. + +Beginning, therefore, to examine one by one, all the particulars that +have been produced, I say, that Figures, as simple Figures, not only +operate not in naturall things, but neither are they ever seperated +from the Corporeall substance[42]: nor have I ever alledged them stript of +sensible Matter, like as also I freely admit, that in our endeavouring +to examine the Diversity of Accidents, dependant upon the variety of +Figures, it is necessary to apply them to Matters, which obstruct not +the various operations of those various Figures: and I admit and +grant, that I should do very ill; if I would experiment the influence +of Acutenesse of edge with a Knife of Wax, applying it to cut an Oak, +because there is no Acuteness in Wax able to cut that very hard wood. +But yet such an Experiment of this Knife, would not be besides the +purpose, to cut curded Milk, or other very yielding Matter: yea, in +such like Matters, the Wax is more commodious than Steel; for finding +the diversity depending upon Angles, more or less Acute, for that Milk +is indifferently cut with a Raisor, and with a Knife, that hath a +blunt edge. It needs, therefore, that regard be had, not only to the +hardness, solidity or Gravity of Bodies, which under divers figures, +are to divide and penetrate some Matters, but it forceth also, that +regard be had, on the other side, to the Resistance of the Matters, to +be divided and penetrated. But since I have in making the Experiment +concerning our Contest; chosen a Matter which penetrates the +Resistance of the water; and in all figures descendes to the Bottome, +the Adversaries can charge me with no defect; yea, I have propounded +so much a more excellent Method than they, in as much as I have +removed all other Causes, of descending or not descending to the +Bottom, and retained the only sole and pure variety of Figures, +demonstrating that the same Figures all descende with the only +alteration of a Grain in weight: which Grain being removed, they +return to float and swim; it is not true, therefore, (resuming the +Example by them introduced) that I have gon{e} about to experiment the +efficacy of Acuteness, in cutting with Matters unable to cut, but with +Matters proportioned to our occasion, since they are subjected to no +other variety, then that alone which depends on the Figure more or +less acute. + + [42] Figure is unseperable from Corporeall Substance. + + [Sidenote: The answer to the Objection against the Experiment of + the Wax.] + +But let us proceed a little farther, and observe, how that indeed the +Consideration, which, they say, ought to be had about the Election of +the Matter, to the end, that it may be proportionate for the making of +our experiment, is needlessly introduced, declaring by the example of +Cutting, that like as Acuteness is inefficient to cut, unless when it +is in a Matter hard and apt to superate the Resistance of the wood or +other Matter, which we intend to cut; so the aptitude of descending or +not descending in water, ought and can only be known in those Matters, +that are able to overcome the Renitence, and superate the Crassitude +of the water. Unto which, I say, that to make distinction and +election, more of this than of that Matter, on which to impress the +Figures for cutting or penetrating this or that Body, as the solidity +or obdurateness of the said Bodies shall be greater or less, is very +necessary: but withall I subjoyn, that such distinction, election and +caution would be superfluous and unprofitable, if the Body to be cut +or penetrated, should have no Resistance, or should not at all +withstand the Cutting or Penitration: and if the Knife were to be used +in cutting a Mist or Smoak, one of Paper would be equally serviceable +with one of _Damascus_ Steel: and so by reason the water hath not any +Resistance against the Penitration of any Solid Body, all choice of +Matter is superfluous and needless, and the Election which I said +above to have been well made of a Matter reciprocall in Gravity to +water, was not because it was necessary, for the overcoming of the +crassitude of the water, but its Gravity, with which only it resists +the sinking of Solid Bodies: and for what concerneth the Resistance of +the crassitude, if we narrowly consider it, we shall find that all +Solid Bodies, as well those that sink, as those that swim, are +indifferently accomodated and apt to bring us to the knowledge of the +truth in question. Nor will I be frighted out of the belief of these +Conclusions, by the Experiments which may be produced against me, of +many severall Woods, Corks, Galls, and, moreover, of subtle slates and +plates of all sorts of Stone and Mettall, apt by means of their +Naturall Gravity, to move towards the Centre of the Earth, the which, +nevertheless, being impotent, either through the Figure (as the +Adversaries thinke) or through Levity, to break and penetrate the +Continuity of the parts of the water, and to distract its union, do +continue to swimm without submerging in the least: nor on the other +side, shall the Authority of _Aristotle_ move me, who in more than one +place, affirmeth the contrary to this, which Experience shews me. + + [Sidenote: No Solid of such Levity, nor of such Figure, but that + it doth penetrate the Crassitude of the Water.] + + [Sidenote: Bodies of all Figures, laid upon the water, do + penetrate its Crassitude, and in what proportion.] + +I return, therefore, to assert, that there is not any Solid of such +Levity, nor of such Figure, that being put upon the water, doth not +divide and penetrate its Crassitude: yea if any with a more +perspicatious eye, shall return to observe more exactly the thin +Boards of Wood, he shall see them to be with part of their thickness +under water, and not only with their inferiour Superficies, to kisse +the Superiour of the water, as they of necessity must have believed, +who have said, that such Boards submerge not, as not being able to +divide the Tenacity of the parts of the water: and, moreover, he shall +see, that subtle shivers of Ebony, Stone or Metall, when they float, +have not only broak the Continuity of the water, but are with all +their thickness, under the Surface of it; and more and more, according +as the Matters are more grave: so that a thin Plate of Lead, shall be +lower than the Surface of the circumfused water, by at least twelve +times the thickness of the Plate, and Gold shall dive below the Levell +of the water, almost twenty times the thickness of the Plate, as I +shall anon declare. + +But let us proceed to evince, that the water yields and suffers it +self to be penetrated by every the lightest Body; and therewithall +demonstrate, how, even by Matters that submerge not, we may come to +know that Figure operates nothing about the going or not going to the +Bottom, seeing that the water suffers it self to be penetrated equally +by every Figure. + + [Sidenote: The Experiment of a Cone, demitted with its Base, and + after with its Point downwards.] + +Make a Cone, or a Piramis of Cypress, of Firre, or of other Wood of +like Gravity, or of pure Wax, and let its height be somewhat great, +namely a handfull, or more, and put it into the water with the Base +downwards: first, you shall see that it will penetrate the water, nor +shall it be at all impeded by the largeness of the Base, nor yet shall +it sink all under water, but the part towards the point shall lye +above it: by which shall be manifest, first, that that Solid forbeares +not to sink out of an inability to divide the Continuity of the water, +having already divided it with its broad part, that in the opinion of +the Adversaries is the less apt to make the division. The Piramid +being thus fixed, note what part of it shall be submerged, and revert +it afterwards with the point downwards, and you shall see that it +shall not dive into the water more than before, but if you observe how +far it shall sink, every person expert in Geometry, may measure, that +those parts that remain out of the water, both in the one and in the +other Experiment are equall to an hair: whence he may manifestly +conclude, that the acute Figure which seemed most apt to part and +penetrate the water, doth not part or penetrate it more than the large +and spacious. + +And he that would have a more easie Experiment, let him take two +Cylinders of the same Matter, one long and small, and the other short, +but very broad, and let him put them in the water, not distended, but +erect and endways: he shall see, if he diligently measure the parts of +the one and of the other, that in each of them the part submerged, +retains exactly the same proportion to that out of the water, and that +no greater part is submerged of that long and small one, than of the +other more spacious and broad: howbeit, this rests upon a very large, +and that upon a very little Superficies of water: therefore the +diversity of Figure, occasioneth neither facility, nor difficulty, in +parting and penetrating the Continuity of the water, and, +consequently, cannot be the Cause of the Natation or Submersion. He +may likewise discover the non operating of variety of Figures, in +arising from the Bottom of the water, towards the Surface, by taking +Wax, and tempering it with a competent quantity of the filings of +Lead, so that it may become a considerable matter graver than the +water: then let him make it into a Ball, and thrust it unto the Bottom +of the water; and fasten to it as much Cork, or other light matter, as +just serveth to raise it, and draw it towards the Surface: for +afterwards changing the same Wax into a thin Cake, or into any other +Figure, that same Cork shall raise it in the same manner to a hair. + +This silenceth not my Antagonists, but they say, that all the +discourse hitherto made by me little importeth to them, and that it +serves their turn, that they have demonstrated in one only particular, +and in what matter, and under what Figure pleaseth them, namely, in a +Board and in a Ball of Ebony, that this put in the water, descends to +the Bottom, and that stays atop to swim: and the Matter being the +same, and the two Bodies differing in nothing but in Figure, they +affirm, that they have with all perspicuity demonstrated and sensibly +manifested what they undertook; and lastly, that they have obtained +their intent. Nevertheless, I believe, and thinke, I can demonstrate, +that that same Experiment proveth nothing against my Conclusion. + + [Sidenote: In Experiments of Natation, the Solid is to be put + into, not upon the water.] + +And first, it is false, that the Ball descends, and the Board not: for +the Board shall also descend, if you do to both the Figures, as the +words of our Question requireth; that is, if you put them both into +the water. + + [Sidenote: The Question of Natation stated.] + + _The words were these. That the Antagonists having an opinion, that + the Figure would alter the Solid Bodies, in relation to the + descending or not descending, ascending or not ascending in the + same_ Medium, _as_ v. gr. _in the same water, in such sort, that, for + Example, a Solid that being of a Sphericall Figure, shall descend + to the Bottom, being reduced into some other Figure, shall not + descend: I holding the contrary, do affirm, that a Corporeall Solid + Body, which reduced into a Sphericall Figure, or any other, shall + go to the Bottom, shall do the like under whatsoever other Figure, + {&}c._ + + [Sidenote: Place defined according to Aristotle.] + +But to be in the water, implies to be placed in the water, and by +_Aristotles_ own Definition of place, to be placed, importeth to be +invironed by the Superficies of the Ambient Body, therefore, then +shall the two Figures be in the water, when the Superficies of the +water, shall imbrace and inviron them: but when the Adversaries shew +the Board of Ebony not descending to the Bottom, they put it not into +the water, but upon the water, where being by a certain impediment (as +by and by we will shew) retained, it is invironed, part by water, and +part by air, which thing is contrary to our agreement, that was, that +the Bodies should be in the water, and not part in water, and part in +air. + + _The which is again made manifest, by the questions being put as + well about the things which go to the Bottom, as those which arise + from the Bottom to swimme, and who sees not that things placed in + the Bottom, must have water about them._ + + [Sidenote: The confutation of the Experiment in the Ebany.] + +It is now to be noted, that the Board of Ebany and the Ball, put into +the water, both sink, but the Ball more swiftly, and the Board more +slowly; and slower and slower, according as it shall be more broad and +thin, and of this Tardity the breadth of the Figure is the true Cause: +But these broad Boards that slowly descend, are the same, that being +put lightly upon the water, do swimm: Therefore, if that were true +which the Adversaries affirm, the same numerical Figure, would in the +same numericall water, cause one while Rest, and another while Tardity +of Motion, which is impossible: for every perticular Figure which +descends to the Bottom[43], hath of necessity its own determinate Tardity +and slowness, proper and naturall unto it, according to which it +moveth, so that every other Tardity, greater or lesser is improper to +its nature: if, therefore, a Board, as suppose of a foot square, +descendeth naturally with six degrees of Tardity, it is impossible, +that it should descend with ten or twenty, unless some new impediment +do arrest it. Much less can it, by reason of the same Figure rest, and +wholly cease to move; but it is necessary, that when ever it resteth, +there do some greater impediment intervene than the breadth of the +Figure. Therefore, it must be somewhat else, and not the Figure, that +stayeth the Board of Ebany above water, of which Figure the only +Effect is the retardment of the Motion, according to which it +descendeth more slowly than the Ball. Let it be confessed, therefore, +rationally discoursing, that the true and sole Cause of the Ebanys +going to the Bottom, is the excess of its Gravity above the Gravity of +the water: and the Cause of the greater or less Tardity, the breadth +of this Figure, or the contractedness of that: but of its Rest, it can +by no means be allowed, that the quallity of the Figure, is the Cause +thereof: aswell, because, making the Tardity greater, according as the +Figure more dilateth, there cannot be so immense a Dilatation, to +which there may not be found a correspondent immence Tardity without +redusing it to Nullity of Motion; as, because the Figures produced by +the Antagonists for effecters of Rest, are the self same that do also +go to the Bottom. + + [43] Every perticular Figure hath its own peculiar Tardity. + +I will not omit another reason, founded also upon Experience, and if +I deceive not my self, manifestly concluding, how that the +Introduction of the breadth or amplitude of Figure, and the Resistance +of the water against penetration, have nothing to do in the Effect of +descending, or ascending, or resting in the water. [D]Take a piece of +wood or other Matter, of which a Ball ascends from the Bottom of the +water to the Surface, more slowly than a Ball of Ebony of the same +bignesse, so that it is manifest, that the Ball of Ebony more readily +divideth the water in descending, than the other in ascending; as for +Example, let the Wood be Walnut-tree. Then take a Board of +Walnut-tree, like and equall to that of Ebony of the Antagonists, +which swims; and if it be true, that this floats above water, by +reason of the Figure, unable through its breadth, to pierce the +Crassitude of the same, the other of Wallnut-tree, without all +question, being thrust unto the Bottom, will stay there, as less apt, +through the same impediment of Figure, to divide the said Resistance +of the water. But if we shall find, and by experience see, that not +only the thin Board, but every other Figure of the same Wallnut-tree +will return to float, as undoubtedly we shall, then I must desier my +opposers to forbear to attribute the floating of the Ebony, unto the +Figure of the Board, in regard that the Resistance of the water is the +same, as well to the ascent, as to the descent, and the force of the +Wallnut-trees ascension, is lesse than the Ebonys force in going to +the Bottom. + + [D] The Figure & Resistance of the Medium against Division, have + nothing to do with the Effect of Natation or Submersion, by an + Experiment in Wallnut tree. + + [Sidenote: An Experiment in Gold, to prove the non-operating of + Figure in Natation and Submersion.] + +Nay, I will say more, that if we shall consider Gold in comparison of +water, we shall find, that it exceeds it in Gravity almost twenty +times, so that the Force and Impetus, wherewith a Ball of Gold goes to +the Bottom, is very great. On the contrary, there want not matters, as +Virgins Wax, and some Woods, which are not above a fiftieth part less +grave than water, whereupon their Ascension therein is very slow, and +a thousand times weaker than the _Impetus_ of the Golds descent: yet +notwithstanding, a plate of Gold swims without descending to the +Bottom, and, on the contrary, we cannot make a Cake of Wax, or thin +Board of Wood, which put in the Bottom of the Water, shall rest there +without ascending. Now if the Figure can obstruct the Penetration, and +impede the descent of Gold, that hath so great an _Impetus_, how can +it choose but suffice to resist the same Penetration of the other +matter in ascending, when as it hath scarce a thousandth part of the +_Impetus_ that the Gold hath in descending? Its therefore, necessary, +that that which suspends the thin Plate of Gold, or Board of Ebony, +upon the water, be some thing that is wanting to the other Cakes and +Boards of Matters less grave than the water; since that being put to +the Bottom, and left at liberty, they rise up to the Surface, without +any obstruction: But they want not for flatness and breadth of Figure: +Therefore, the spaciousnesse of the Figure, is not that which makes +the Gold and Ebony to swim. + +And, because, that the excess of their Gravity above the Gravity of +the water, is questionless the Cause of the sinking of the flat piece +of Ebony, and the thin Plate of Gold, when they go to the Bottom, +therefore, of necessity, when they float, the Cause of their staying +above water, proceeds from Levity, which in that case, by some +Accident, peradventure not hitherto observed, cometh to meet with the +said Board, rendering it no longer as it was before, whilst it did +sink more ponderous than the water, but less. + +Now, let us return to take the thin Plate of Gold, or of Silver, or +the thin Board of Ebony, and let us lay it lightly upon the water, so +that it stay there without sinking, and diligently observe its effect. +And first, see how false the assertion of _Aristotle_, and our +oponents is, to wit, that it stayeth above water, through its +unability to pierce and penetrate the Resistance of the waters +Crassitude: for it will manifestly appear, not only that the said +Plates have penetrated the water, but also that they are a +considerable matter lower than the Surface of the same, the which +continueth eminent, and maketh as it were a Rampert on all sides, +round about the said Plates, the profundity of which they stay +swimming: and, according as the said Plates shall be more grave than +the water, two, four, ten or twenty times, it is necessary, that their +Superficies do stay below the universall Surface of the water, so much +more, than the thickness of those Plates, as we shal more distinctly +shew anon. In the mean space, for the more easie understanding of what +I say, observe with me a little the present Scheme: in which let us +suppose the Surface of the water to be distended, according to the +Lines F L D B, upon which if one shall put a board of matter +specifically more grave than water, but so lightly that it submerge +not, it shall not rest any thing above, but shall enter with its whole +thickness into the water: and, moreover, shall sink also, as we see by +the Board A I, O I, whose breadth is wholly sunk into the water, the +little Ramperts of water L A and D O incompassing it, whose +Superficies is notably higher than the Superficies of the Board. See +now whether it be true, that the said Board goes not to the Bottom, as +being of Figure unapt to penetrate the Crassitude of the water. + +[Illustration] + + [Sidenote: Why solids having penitrated the Water, do not proceed + to a totall Submersion.] + +But, if it hath already penetrated, and overcome the Continuity of +the water, & is of its own nature more grave than the said water, why +doth it not proceed in its sinking, but stop and suspend its self +within that little dimple or cavitie, which with its ponderosity it +hath made in the water? I answer; because that in submerging it self, +so far as till its Superficies come to the Levell with that of the +water, it loseth a part of its Gravity, and loseth the rest of it as +it submergeth & descends beneath the Surface of the water, which +maketh Ramperts and Banks round about it, and it sustaines this loss +by means of its drawing after it, and carrying along with it, the Air +that is above it, and by Contact adherent to it, which Air succeeds to +fill the Cavity that is invironed by the Ramperts of water; so that +that which in this case descends and is placed in the water, is not +only the Board of Ebony or Plate of Iron, but a composition of Ebony +and Air, from which resulteth a Solid no longer superiour in Gravity +to the water, as was the simple Ebony, or the simple Gold. And, if we +exactly consider, what, and how great the Solid is, that in this +Experiment enters into the water, and contrasts with the Gravity of +the same, it will be found to be all that which we find to be beneath +the Surface of the water, the which is an aggregate and Compound of a +Board of Ebony, and of almost the like quantity of Air, or a Mass +compounded of a Plate of Lead, and ten or twelve times as much Air. +But, Gentlemen, you that are my Antagonists in our Question, we +require the Identity of Matter, and the alteration only of the Figure; +therefore, you must remove that Air, which being conjoyned with the +Board, makes it become another Body less grave than the Water, and put +only the Ebony into the Water, and you shall certainly see the Board +descend to the Bottom; and, if that do not happen, you have got the +day. And to seperate the Air from the Ebony[44], there needs no more but +only to bath the Superficies of the said Board with the same Water: +for the Water being thus interposed between the Board and the Air, the +other circumfused Water shall run together without any impediment, and +shall receive into it the sole and bare Ebony, as it was to do. + + [44] How to seperate the Air from Solids in demitting them into + the water. + +But, me thinks I hear some of the Adversaries cunningly opposing this, +and telling me, that they will not yield, by any means, that their +Board be wetted, because the weight added thereto by the Water, by +making it heavier than it was before, draws it to the Bottom, and that +the addition of new weight is contrary to our agreement, which was, +that the Matter be the same. + +To this, I answer, first; that treating of the operation of Figure +in Bodies put into the Water, none can suppose them to be put into the +Water without being wet; nor do I desire more to be done to the Board, +then I will give you leave to do to the Ball. Moreover, it is untrue, +that the Board sinks by vertue of the new Weight added to it by the +Water, in the single and slight bathing of it: for I will put ten or +twenty drops of Water upon the same Board, whilst it is sustained upon +the water; which drops, because not conjoyned with the other Water +circumfused, shall not so encrease the weight of it, as to make it +sink: but if the Board being taken out, and all the water wiped off +that was added thereto, I should bath all its Superficies with one +only very small drop, and put it again upon the water, without doubt +it shall sink, the other Water running to cover it, not being retained +by the superiour Air; which Air by the interposition of the thin vail +of water, that takes away its Contiguity unto the Ebony, shall without +Renitence be seperated, nor doth it in the least oppose the succession +of the other Water: but rather, to speak better, it shall descend +freely; because it shall be all invironed and covered with water, as +soon as its superiour Superficies, before vailed with water, doth +arrive to the Levell of the universall Surface of the said water. To +say, in the next place, that water can encrease the weight of things +that are demitted into it, is most false; for water hath no Gravity in +water[45], since it descends not: yea, if we would well consider what any +immense Mass of water doth put upon a grave Body; that is placed in +it, we shall find experimentally, that it, on the contrary, will +rather in a great part deminish the weight of it[46], and that we may be +able to lift an huge Stone from the Bottom of the water, which the +water being removed, we are not able to stir. Nor let them tell me by +way of reply, that although the superposed water augment not the +Gravity of things that are in it, yet it increaseth the ponderosity of +those that swim, and are part in the water and part in the Air, as is +seen, for Example, in a Brass Ketle[47], which whilst it is empty of +water, and replenished only with Air shall swim, but pouring of Water +therein, it shall become so grave, that it shall sink to the Bottom, +and that by reason of the new weight added thereto. To this I will +return answer, as above, that the Gravity of the Water, contained in +the Vessel is not that which sinks it to the Bottom, but the proper +Gravity of the Brass, superiour to the Specificall Gravity of the +Water: for if the Vessel were less grave than water, the Ocean would +not suffice to submerge it[48]. And, give me leave to repeat it again, as +the fundamentall and principall point in this Case, that the Air +contained in this Vessel before the infusion of the Water, was that +which kept it a-float[49], since that there was made of it, and of the +Brass, a Composition less grave than an equall quantity of Water: and +the place that the Vessel occupyeth in the Water whilst it floats, is +not equall to the Brass alone, but to the Brass and to the Air +together, which filleth that part of the Vessel that is below the +Levell of the water: Moreover, when the Water is infused, the Air is +removed, and there is a composition made of Brass and of water, more +grave _in specie_ than the simple water, but not by vertue of the +water infused, as having greater Specifick Gravity than the other +water, but through the proper Gravity of the Brass, and through the +alienation of the Air. Now, as he that should say that Brass, that by +its nature goes to the Bottom, being formed into the Figure of a +Ketle[50], acquireth from that Figure a vertue of lying in the Water +without sinking, would say that which is false; because that Brass +fashioned into any whatever Figure, goeth always to the Bottom, +provided, that that which is put into the water be simple Brass; and +it is not the Figure of the Vessel that makes the Brass to float, but +it is because that that is not purely Brass which is put into the +water, but an aggregate of Brass and of Air: so is it neither more nor +less false, that a thin Plate of Brass or of Ebony, swims by vertue of +its dilated & broad Figure: for the truth is, that it bares up without +submerging, because that that which is put in the water, is not pure +Brass or simple Ebony, but an aggregate of Brass and Air, or of Ebony +and Air. And, this is not contrary unto my Conclusion, the which, +(having many a time seen Vessels of Mettall, and thin pieces of +diverse grave Matters float, by vertue of the Air conjoyned with them) +did affirm, That Figure was not the Cause of the Natation or +Submersion of such Solids as were placed in the water. Nay more, I +cannot omit, but must tell my Antagonists, that this new conceit of +denying that the Superficies of the Board should be bathed, may beget +in a third person an opinion of a poverty of Arguments of defence on +their part, since that such bathing was never insisted upon by them in +the beginning of our Dispute, and was not questioned in the least, +being that the Originall of the discourse arose upon the swiming of +Flakes of Ice, wherein it would be simplicity to require that their +Superficies might bedry: besides, that whether these pieces of Ice be +wet or dry they alwayes swim, and as the Adversaries say, by reason of +the Figure. + + [45] Water hath no Gravity in Water. + + [46] Water deminisheth the Gravity of Solids immerged therein. + + [47] The Experiment of a brass Ketle swiming when empty, & sinking + when full, alledged to prove that water gravitates in water, + answered. + + [48] An Ocean sufficeth not to sink a Vessel specifically less + grave than water. + + [49] Air, the Cause of the Natation of empty Vessels of Matters + graver _in specie_ than the water. + + [50] Neither Figure, nor the breadth of Figure, is the Cause of + Natation. + +Some peradventure, by way of defence, may say, that wetting the Board +of Ebony, and that in the superiour Superficies, it would, though of +it self unable to pierce and penetrate the water, be born downwards, +if not by the weight of the additionall water, at least by that desire +and propension that the superiour parts of the water have to re-unite +and rejoyn themselves: by the Motion of which parts, the said Board +cometh in a certain manner, to be depressed downwards. + + [Sidenote: The Bathed Solid descends not out of any affectation + of union in the upper parts of the water.] + +This weak Refuge will be removed, if we do but consider, that the +repugnancy of the inferiour parts of the water, is as great against +Dis-union, as the Inclination of its superiour parts is to union: nor +can the uper unite themselves without depressing the board, nor can it +descend without disuniting the parts of the nether Water: so that it +doth follow, by necessary consequence, that for those respects, it +shall not descend. Moreover, the same that may be said of the upper +parts of the water, may with equall reason be said of the nether, +namely, that desiring to unite, they shall force the said Board +upwards. + +Happily, some of these Gentlemen that dissent from me, will wonder, +that I affirm, that the contiguous superiour Air is able to sustain +that Plate of Brass or of Silver, that stayeth above water; as if I +would in a certain sence allow the Air[51], a kind of Magnetick vertue of +sustaining the grave Bodies, with which it is contiguous. To satisfie +all I may, to all doubts, I have been considering how by some other +sensible Experiment I might demonstrate, how truly that little +contiguous and superiour Air sustaines those Solids, which being by +nature apt to descend to the Bottom, being placed lightly on the water +submerge not, unless they be first thorowly bathed; and have found, +that one of these Bodies having descended to the Bottom, by +conveighing to it (without touching it in the least) a little Air, +which conjoyneth with the top of the same, it becometh sufficient, not +only, as before to sustain it, but also to raise it, and to carry it +back to the top, where it stays and abideth in the same manner, till +such time, as the assistance of the conjoyned Air is taken away. And +to this effect, I have taken a Ball of Wax, and made it with a little +Lead, so grave, that it leasurely descends to the Bottom, making with +all its Superficies very smooth and pollite: and this being put gently +into the water, almost wholly submergeth, there remaining vissible +only a little of the very top[52], the which so long as it is conjoyned +with the Air, shall retain the Ball a-top, but the Contiguity of the +Air taken away by wetting it, it shall descend to the Bottom and there +remain. Now to make it by vertue of the Air, that before sustained it +to return again to the top, and stay there, thrust into the water a +Glass reversed with the mouth downwards, the which shall carry with it +the Air it contains, and move this towards the Ball, abasing it till +such time that you see, by the transparency of the Glass, that the +contained Air do arrive to the summity of the _B_all[53]: then gently +withdraw the Glass upwards, and you shall see the _B_all to rise, and +afterwards stay on the top of the water[54], if you carefully part the +Glass and the water without overmuch commoving and disturbing it. +There is, therefore, a certain affinity between the Air and other +Bodies, which holds them unied, so, that they seperate not without a +kind of violence. The same likewise is seen in the water[55]; for if we +shall wholly submerge some Body in it, so that it be thorowly bathed, +in the drawing of it afterwards gently out again, we shall see the +water follow it, and rise notably above its Surface, before it +seperates from it. Solid Bodies, also[56], if they be equall and alike in +Superficies, so, that they make an exact Contact without the +interposition of the least Air, that may part them in the seperation +and yield untill that the ambient _Medium_ succeeds to replenish the +place, do hold very firmly conjoyned, and are not to be seperated +without great force but, because, the Air, Water, and other Liquids, +very expeditiously shape themselves to contact with any Solid +_B_odies, so that their Superficies do exquisitely adopt themselves to +that of the Solids, without any thing remaining between them, +therefore, the effect of this Conjunction and Adherence is more +manifestly and frequently observed in them, than in hard and +inflexible Bodies, whose Superficies do very rarely conjoyn with +exactness of Contact[57]. This is therefore that Magnetick vertue, which +with firm Connection conjoyneth all Bodies, that do touch without the +interposition of flexible fluids; and, who knows, but that that a +Contact, when it is very exact, may be a sufficient Cause of the Union +and Continuity of the parts of a naturall _B_ody? + + [51] _A_ Magnetisme in the _A_ir, by which it bears up those + Solids in the water, that are contiguous with it. + + [52] The Effect of the Airs Contiguity in the Natation of Solids. + + [53] The force of Contact. + + [54] _A_n Affectation of Conjunction betwixt Solids and the Air + contiguous to them. + + [55] The like affectation of Conjunction betwixt Solids & the + water. + + [56] Also the like affectation and Conjunction betwixt Solids + themselves. + + [57] Contact may be the Cause of the Continuity of Naturall + Bodies. + +Now, pursuing my purpose, I say; that it needs not, that we have +recourse to the Tenacity, that the parts of the water have amongst +themselves, by which they resist and oppose Division, Distraction, and +Seperation, because there is no such Coherence and Resistance of +Division for if there were, it would be no less in the internall parts +than in those nearer the superiour or externall Surface, so that the +same Board, finding alwayes the same Resistance and Renitence, would +no less stop in the middle of the water than about the Surface, which +is false. Moreover, what Resistance can we place in the Continuity of +the water, if we see that it is impossible to find any Body of +whatsoever Matter, Figure or Magnitude, which being put into the +water, shall be obstructed and impeded by the Tenacity of the parts of +the water to one another, so, but that it is moved upwards or +downwards, according as the Cause of their Motion transports it? And, +what greater proof of it can we desier, than that which we daily see +in Muddy waters, which being put into Vessels to be drunk, and being, +after some hours setling[58], still, as we say, thick in the end, after +four or six dayes they are wholly setled, and become pure and clear? +Nor can their Resistance of Penetration stay those impalpable and +insensible Atomes of Sand, which by reason of their exceeding small +force, spend six dayes in descending the space of half a yard. + + [58] The settlement of _M_uddy Water, proveth that that Element + hath no aversion to Division. + + _Nor let them say, that the seeing of such small Bodies, consume + six dayes in descending so little a way, is a sufficient Argument + of the Waters Resistance of Division; because that is no resisting + of Division, but a retarding of Motion; and it would be simplicity + to say, that a thing opposeth Division[59], and that in the same + instant, it permits it self to be divided: nor doth the Retardation + of Motion at all favour the Adversaries cause, for that they are to + instance in a thing that wholly prohibiteth Motion, and procureth + Rest; it is necessary, therefore, to find out Bodies that stay in + the water, if one would shew its repugnancy to Division, and not + such as move in it, howbeit but slowly._ + + [59] Water cannot oppose division, and at the same time permit it + self to be divided. + +What then is this Crassitude of the water, with which it resisteth +Division? What, I beseech you, should it be, if we (as we have said +above) with all diligence attempting the reduction of a Matter into so +like a Gravity with the water, that forming it into a dilated Plate it +rests suspended as we have said, between the two waters, it be +impossible to effect it, though we bring them to such an +Equiponderance, that as much Lead as the fourth part of a Grain of +Musterd-seed, added to the same expanded Plate, that in Air [_i. e. +out of the water_] shall weigh four or six pounds, sinketh it to the +Bottom, and being substracted, it ascends to the Surface of the water? +I cannot see, (if what I say be true, as it is most certain) what +minute vertue and force we can possibly find or imagine, to which the +Resistance of the water against Division and Penetration is not +inferiour; whereupon, we must of necessity conclude that it is +nothing: because, if it were of any sensible power, some large Plate +might be found or compounded of a Matter alike in Gravity to the +water, which not only would stay between the two waters; but, +moreover, should not be able to descend or ascend without notable +force. We may likewise collect the same from an other Experiment[60], +shewing that the Water gives way also in the same manner to +transversall Division; for if in a setled and standing water we should +place any great Mass that goeth not to the bottom, drawing it with a +single Womans Hair, we might carry it from place to place without any +opposition, and this whatever Figure it hath, though that it possess a +great space of water, as for instance, a great Beam would do moved +side-ways. Perhaps some might oppose me and say, that if the +Resistance of water against Division, as I affirm, were nothing; Ships +should not need such a force of Oars and Sayles for the moving of them +from place to place in a tranquile Sea, or standing Lake. To him that +should make such an objection, I would reply[61], that the water +contrasteth not against, nor simply resisteth Division, but a sudden +Division, and with so much greater Renitence, by how much greater the +Velocity is: and the Cause of this Resistance depends not on +Crassitude, or any other thing that absolutely opposeth Division, but +because that the parts of the water divided, in giving way to that +Solid that is moved in it, are themselves also necessitated locally to +move, some to the one side, and some to the other, and some downwards: +and this must no less be done by the waves before the Ship, or other +Body swimming through the water, than by the posteriour and +subsequent; because, the Ship proceeding forwards, to make it self a +way to receive its Bulk, it is requisite, that with the Prow it +repulse the adjacent parts of the water, as well on one hand as on the +other, and that it move them as much transversly, as is the half of +the breadth of the Hull: and the like removall must those waves make, +that succeeding the Poump do run from the remoter parts of the Ship +towards those of the middle, successively to replenish the places, +which the Ship in advancing forwards, goeth, leaving vacant. Now, +because, all Motitions are made in Time[62], and the longer in greater +time: and it being moreover true, that those Bodies that in a certain +time are moved by a certain power such a certain space, shall not be +moved the same space, and in a shorter Time, unless by a greater +Power: therefore, the broader Ships move slower than the narrower, +being put on by an equall Force: and the same Vessel requires so much +greater force of Wind, or Oars, the faster it is to move. + + [60] An hair will draw a great Mass thorow the Water; which + proveth, that it hath no Resistance against transversall + Division. + + [61] How ships are moved in the water. + + [62] Bodies moved a certain space in a certain Time, by a + certain power, cannot be moved the same space and in a shorter + time, but by a greater power. + + _But yet for all this, any great Mass swimming in a standing Lake, + may be moved by any petit force; only it is true, that a lesser + force more slowly moves it: but if the waters Resistance of + Division, were in any manner sensible, it would follow, that the + said Mass, should, notwithstanding the percussion of some sensible + force, continue immoveable, which is not so[63]. Yea, I will say + farther, that should we retire our selves into the more internall + contemplation of the Nature of water and other Fluids, perhaps we + should discover the Constitution of their parts to be such, that + they not only do not oppose Division, but that they have not any + thing in them to be divided: so that the Resistance that is + observed in moving through the water[64], is like to that which we meet + with in passing through a great Throng of People, wherein we find + impediment, and not by any difficulty in the Division, for that + none of those persons are divided whereof the Croud is composed, + but only in moving of those persons side-ways which were before + divided and disjoyned: and thus we find Resistance in thrusting a + Stick into an heap of Sand, not because any part of the Sand is to + be cut in pieces, but only to be moved and raised[65]. Two manners of + Penetration, therefore, offer themselves to us, one in Bodies, + whose parts were continuall, and here Division seemeth necessary, + the other in the aggregates of parts not continuall, but contiguous + only[66], and here there is no necessity of dividing but of moving + only. Now, I am not well resolved, whether water and other Fluids + may be esteemed to be of parts continuall or contiguous only[67]; yet I + find my self indeed inclined to think that they are rather + contiguous (if there be in Nature no other manner of aggregating, + than by the union, or by the touching of the extreams:) and I am + induced thereto by the great difference that I see between the + Conjunction of the parts of an hard or Solid Body[68], and the + Conjunction of the same parts when the same Body shall be made + Liquid and Fluid: for if, for example, I take a Mass of Silver or + other Solid and hard Mettall, I shall in dividing it into two + parts, find not only the resistance that is found in the moving of + it only[69], but an other incomparably greater, dependent on that + vertue, whatever it be, which holds the parts united: and so if we + would divide again those two parts into other two, and successively + into others and others, we should still find a like Resistance, but + ever less by how much smaller the parts to be divided shall be; but + if, lastly, employing most subtile and acute Instruments, such as + are the most tenuous parts of the Fire, we shall resolve it + (perhaps) into its last and least Particles, there shall not be + left in them any longer either Resistance of Division, or so much + as a capacity of being farther divided, especially by Instruments + more grosse than the acuities of Fire: and what Knife or Rasor put + into well melted Silver can we finde, that will divide a thing + which surpasseth the separating power of Fire? Certainly none: + because either the whole shall be reduced to the most minute and + ultimate Divisions, or if there remain parts capable still of other + Subdidivisions, they cannot receive them, but only from acuter + Divisors than Fire; but a Stick or Rod of Iron, moved in the melted + Metall, is not such a one. Of a like Constitution and Consistence, + I account the parts of Water[70], and other Liquids to be, namely, + incapable of Division by reason of their Ienuity; or if not + absolutely indivisible, yet at least not to be divided by a Board, + or other Solid Body, palpable unto the hand, the Sector being + alwayes required to be more sharp than the Solid to be cut. Solid + Bodies, therefore, do only move, and not divide the Water[71], when put + into it; whose parts being before divided to the extreamest + minuity, and therefore capable of being moved, either many of them + at once, or few, or very few, they soon give place to every small + Corpuscle, that descends in the same: for that, it being little and + light, descending in the Air, and arriving to the Surface of the + Water, it meets with Particles of Water more small, and of less + Resistance against Motion and Extrusion, than is its own prement + and extrusive force; whereupon it submergeth, and moveth such a + portion of them, as is proportionate to its Power. There is not, + therefore, any Resistance in Water against Division, nay, there is + not in it any divisible parts. I adde; moreover, that in case yet + there should be any small Resistance found (which is absolutely + false)[72] haply in attempting with an Hair to move a very great natant + Machine, or in essaying by the addition of one small Grain of Lead + to sink, or by removall of it to raise a very broad Plate of + Matter, equall in Gravity with Water, (which likewise will not + happen, in case we proceed with dexterity) we may observe that that + Resistance is a very different thing from that which the + Adversaries produce for the Cause of the Natation of the Plate of + Lead or Board of Ebony, for that one may make a Board of Ebony, + which being put upon the Water swimmeth, and cannot be submerged, + no not by the addition of an hundred Grains of Lead put upon the + same, and afterwards being bathed, not only sinks, though the said + Lead be taken away, but though moreover a quantity of Cork, or of + some other light Body fastened to it, sufficeth not to hinder it + from sinking unto the bottome: so that you see, that although it + were granted that there is a certain small Resistance of Division + found in the substance of the Water, yet this hath nothing to do + with that Cause which supports the Board above the Water, with a + Resistance an hundred times greater than that which men can find in + the parts of the Water: nor let them tell me, that only the Surface + of the Water hath such Resistance[73], and not the internall parts, or + that such Resistance is found greatest in the beginning of the + Submersion, as it also seems that in the beginning, Motion meets + with greater opposition, than in the continuance of it; because, + first, I will permit, that the Water be stirred, and that the + superiour parts be mingled with the middle[74], and inferiour parts, or + that those above be wholly removed, and those in the middle only + made use off, and yet you shall see the effect for all that, to be + still the same: Moreover, that Hair which draws a Beam through the + Water, is likewise to divide the upperparts, and is also to begin + the Motion, and yet it begins it, and yet it divides it: and + finally, let the Board of Ebony be put in the midway, betwixt the + bottome and the top of the Water, and let it there for awhile be + suspended and setled, and afterwards let it be left at liberty, and + it will instantly begin its Motion, and will continue it unto the + bottome. Nay, more, the Board so soon as it is dimitted upon the + Water, hath not only begun to move and divide it, but is for a good + space dimerged into it._ + + [63] The parts of Liquids, so farre from resisting Division, that + they contain not any thing that may be divided. + + [64] The Resistance a Solid findeth in moving through the water, + like to that we meet with in passing through a throng of people: + + [65] Or in thrusting a Stick into an heap of Sand. + + [66] Two kinds of Penetration, one in Bodies continuall, the other + in Bodies only contiguous. + + [67] Water consists not of continuall, but only of contiguous + parts. + + [68] _Se{e} what satisfaction he hath given, as to this point, in + Lib. de Motu. Dial. 2._ + + [69] Great difference betwixt the Conjunction of the parts of a + Body when Solid, and when fluid. + + [70] Water consists of parts that admit of no farther division. + + [71] Solids dimitted into the water, do onely move, and not divide + it. + + [72] If there were any Resistance of Division in water, it must + needs be small, in that it is overcome by an Hair, a Grain of + Lead, or a slight bathing of the Solid. + + [73] The uper parts of the Water, do no more resist Division than + the middle or lower parts. + + [74] Waters Resistance of division, not greater in the beginning + of the Submersion. + +Let us receive it, therefore, for a true and undoubted Conclusion, +That the Water hath not any Renitence against simple Division, and +that it is not possible to find any Solid Body, be it of what Figure +it will, which being put into the Water, its Motion upwards or +downwards, according as it exceedeth, or shall be exceeded by the +Water in Gravity (although such excesse and difference be insensible) +shall be prohibited, and taken away, by the Crassitude of the said +Water. When, therefore, we see the Board of Ebony, or of other Matter, +more grave than the Water, to stay in the Confines of the Water and +Air, without submerging, we must have recourse to some other +Originall, for the investing the Cause of that Effect, than to the +breadth of the Figure, unable to overcome the Renitence with which the +Water opposeth Division, since there is no Resistance; and from that +which is not in being, we can expect no Action. It remains most true, +therefore, as we have said before, that this so succeds, for that that +which in such manner put upon the water, not the same Body with that +which is put _into_ the Water: because this which is put _into_ the +Water, is the pure Board of Ebony, which for that it is more grave +than the Water, sinketh, and that which is put _upon_ the Water, is a +Composition of Ebony, and of so much Air, that both together are +specifically less grave than the Water, and therefore they do not +descend. + +I will farther confirm this which I say. Gentlemen, my Antagonists, we +are agreed, that the excess or defect of the Gravity of the Solid, +unto the Gravity of the Water, is the true and proper Cause of +Natation or Submersion. + + [Sidenote: Great Caution to be had in experimenting the operation + of Figure in Natation.] + +Now, if you will shew that besides the former Cause, there is another +which is so powerfull, that it can hinder and remove the Submersion of +those very Solids, that by their Gravity sink, and if you will say, +that this is the breadth or ampleness of Figure, you are oblieged, +when ever you would shew such an Experiment, first to make the +circumstances certain, that that Solid which you put into the Water, +be not less grave _in specie_ than it, for if you should not do so, +any one might with reason say, that not the Figure, but the Levity was +the cause of that Natation. But I say, that when you shall dimit a +Board of Ebony into the Water, you do not put therein a Solid more +grave _in specie_ than the Water, but one lighter, for besides the +Ebony, there is in the Water a Mass of Air, united with the Ebony, and +such, and so light, that of both there results a Composition less +grave than the Water: See, therefore, that you remove the Air, and put +the Ebony alone into the Water, for so you shall immerge a Solid more +grave then the Water, and if this shall not go to the Bottom, you have +well Philosophized and I ill. + +Now, since we have found the true Cause of the Natation of those +Bodies, which otherwise, as being graver than the Water, would descend +to the bottom, I think, that for the perfect and distinct knowledge of +this business, it would be good to proceed in a way of discovering +demonstratively those particular Accidents that do attend these +effects, and, + + + + +PROBL. I. + + [Sidenote: To finde the proportion Figures ought to have to the + waters Gravity, that by help of the contiguous Air, they may + swim.] + + _To finde what proportion severall Figures of different Matters + ought to have, unto the Gravity of the Water, that so they may be + able by vertue of the Contiguous Air to stay afloat._ + + +[Illustration] + +Let, therefore, for better illustration, D F N E be a Vessell, +wherein the water is contained, and suppose a Plate or Board, whose +thickness is comprehended between the Lines I C and O S, and let it be +of Matter exceeding the water in Gravity, so that being put upon the +water, it dimergeth and abaseth below the Levell of the said water, +leaving the little Banks A I and B C, which are at the greatest height +they can be, so that if the Plate I S should but descend any little +space farther, the little Banks or Ramparts would no longer consist, +but expulsing the Air A I C B, they would diffuse themselves over the +Superficies I C, and would submerge the Plate. The height A I B C is +therefore the greatest profundity that the little Banks of water admit +of. Now I say, that from this, and from the proportion in Gravity, +that the Matter of the Plate hath to the water, we may easily finde of +what thickness, at most, we may make the said Plates, to the end, they +may be able to bear up above water: for if the Matter of the Plate or +Board I S were, for Example, as heavy again as the water, a Board of +that Matter shall be, at the most of a thickness equall to the +greatest height of the Banks, that is, as thick as A I is high: which +we will thus demonstrate. Let the Solid I S be double in Gravity to +the water, and let it be a regular Prisme, or Cylinder, to wit, that +hath its two flat Superficies, superiour and inferiour, alike and +equall, and at Right Angles with the other laterall Superficies, and +let its thickness I O be equall to the greatest Altitude of the Banks +of water: I say, that if it be put upon the water, it will not +submerge: for the Altitude A I being equall to the Altitude I O, the +Mass of the Air A B C I shall be equall to the Mass of the Solid C I O +S: and the whole Mass A O S B double to the Mass I S; And since the +Mass of the Air A C, neither encreaseth nor diminisheth the Gravity of +the Mass I S, and the Solid I S was supposed double in Gravity to the +water; Therefore as much water as the Mass submerged A O S B, +compounded of the Air A I C B, and of the Solid I O S C, weighs just +as much as the same submerged Mass A O S B: but when such a Mass of +water, as is the submerged part of the Solid, weighs as much as the +said Solid, it descends not farther, but resteth, as by (_a_) +_Archimedes_[75], and above by us, hath been demonstrated: Therefore, I S +shall descend no farther, but shall rest. And if the Solid I S shall +be Sesquialter in Gravity to the water, it shall float, as long as its +thickness be not above twice as much as the greatest Altitude of the +Ramparts of water, that is, of A I. For I S being Sesquialter in +Gravity to the water, and the Altitude O I, being double to I A, the +Solid submerged A O S B, shall be also Sesquialter in Mass to the +Solid I S. And because the Air A C, neither increaseth nor diminisheth +the ponderosity of the Solid I S: Therefore, as much water in quantity +as the submerged Mass A O S B, weighs as much as the said Mass +submerged: And, therefore, that Mass shall rest. And briefly in +generall. + + [75] Of Natation Lib. 1. Prop. 3. + +[Illustration] + + + + +THEOREME. VI. + + [Sidenote: The proportion of the greatest thickness of Solids, + beyond which encreased they sink.] + + _When ever the excess of the Gravity of the Solid above the Gravity + of the Water, shall have the same proportion to the Gravity of + the Water, that the Altitude of the Rampart, hath to the + thickness of the Solid, that Solid shall not sink, but being + never so little thicker it shall._ + + +[Illustration] + +Let the Solid I S be superior in Gravity to the water, and of such +thickness, that the Altitude of the Rampart A I, be in proportion to +the thickness of the Solid I O, as the excess of the Gravity of the +said Solid I S, above the Gravity of a Mass of water equall to the +Mass I S, is to the Gravity of the Mass of water equall to the Mass I +S. I say, that the Solid I S shall not sinke, but being never so +little thicker it shall go to the bottom: For being that as A I is to +I O, so is the Excess of the Gravity of the Solid I S, above the +Gravity of a Mass of water equall to the Mass I S, to the Gravity of +the said Mass of water: Therefore, compounding, as A O is to O I, so +shall the Gravity of the Solid I S, be to the Gravity of a Mass of +water equall to the Mass I S: And, converting, as I O is to O A, so +shall the Gravity of a Mass of water equall to the Mass I S, be to the +Gravity of the Solid I S: But as I O is to O A, so is a Mass of water +I S, to a Mass of water equall to the Mass A B S O: and so is the +Gravity of a Mass of water I S, to the Gravity of a Mass of water A S: +Therefore as the Gravity of a Mass of water, equall to the Mass I S, +is to the Gravity of the Solid I S, so is the same Gravity of a Mass +of water I S, to the Gravity of a Mass of Water A S: Therefore the +Gravity of the Solid I S, is equall to the Gravity of a Mass of water +equall to the Mass A S: But the Gravity of the Solid I S, is the same +with the Gravity of the Solid A S, compounded of the Solid I S, and of +the Air A B C I. Therefore the whole compounded Solid A O S B, weighs +as much as the water that would be comprised in the place of the said +Compound A O S B: And, therefore, it shall make an _Equilibrium_ and +rest, and that same Solid I O S C shall sinke no farther. But if its +thickness I O should be increased, it would be necessary also to +encrease the Altitude of the Rampart A I, to maintain the due +proportion: But by what hath been supposed, the Altitude of the +Rampart A I, is the greatest that the Nature of the Water and Air do +admit, without the waters repulsing the Air adherent to the +Superficies of the Solid I C, and possessing the space A I C B: +Therefore, a Solid of greater thickness than I O, and of the same +Matter with the Solid I S, shall not rest without submerging, but +shall descend to the bottome: which was to be demonstrated. In +consequence of this that hath been demonstrated, sundry and various +Conclusions may be gathered, by which the truth of my principall +Proposition comes to be more and more confirmed, and the imperfection +of all former Argumentations touching the present Question cometh to +be discovered. + +_And first we gather from the things demonstrated, that,_ + + + + +THEOREME VII. + + [Sidenote: The heaviest Bodies may swimme.] + + _All Matters, how heavy soever, even to Gold it self, the heaviest + of all Bodies, known by us, may float upon the Water._ + + +Because its Gravity being considered to be almost twenty times greater +than that of the water, and, moreover, the greatest Altitude that the +Rampart of water can be extended to, without breaking the Contiguity +of the Air, adherent to the Surface of the Solid, that is put upon the +water being predetermined, if we should make a Plate of Gold so thin, +that it exceeds not the nineteenth part of the Altitude of the said +Rampart, this put lightly upon the water shall rest, without going to +the bottom: and if Ebony shall chance to be in sesquiseptimall +proportion more grave than the water, the greatest thickness that can +be allowed to a Board of Ebony, so that it may be able to stay above +water without sinking, would be seaven times more than the height of +the Rampart Tinn, _v. gr._ eight times more grave than water, shall +swimm as oft as the thickness of its Plate, exceeds not the 7th part +of the Altitude of the Rampart. + + [Sidenote: _He elsewhere cites this as a Proposition, therefore I + make it of that number._] + +And here I will not omit to note, as a second Corrollary dependent +upon the things demonstrated, that, + + + + +THEOREME VIII. + + [Sidenote: Natation and Submersion, collected from the thickness, + excluding the length and breadth of Plates.] + + _The Expansion of Figure not only is not the Cause of the Natation + of those grave Bodies, which otherwise do submerge, but also the + determining what be those Boards of Ebony, or Plates of Iron or + Gold that will swimme, depends not on it, rather that same + determination is to be collected from the only thickness of those + Figures of Ebony or Gold, wholly excluding the consideration of + length and breadth, as having no wayes any share in this Effect._ + + +It hath already been manifested, that the only cause of the Natation +of the said Plates, is the reduction of them to be less grave than the +water, by means of the connexion of that Air, which descendeth +together with them, and possesseth place in the water; which place so +occupyed, if before the circumfused water diffuseth it self to fill +it, it be capable of as much water, as shall weigh equall with the +Plate, the Plate shall remain suspended, and sinke no farther. + +Now let us see on which of these three dimensions of the Solid +depends the terminating, what and how much the Mass of that ought to +be, that so the assistance of the Air contiguous unto it, may suffice +to render it specifically less grave than the water, whereupon it may +rest without Submersion. It shall undoubtedly be found, that the +length and breadth have not any thing to do in the said determination, +but only the height, or if you will the thickness: for, if we take a +Plate or Board, as for Example, of Ebony, whose Altitude hath unto the +greatest possible Altitude of the Rampart, the proportion above +declared, for which cause it swims indeed, but yet not if we never so +little increase its thickness; I say, that retaining its thickness, +and encreasing its Superficies to twice, four times, or ten times its +bigness, or dminishing it by dividing it into four, or six, or twenty, +or a hundred parts, it shall still in the same manner continue to +float: but encreasing its thickness only a Hairs breadth, it will +alwaies submerge, although we should multiply the Superficies a +hundred and a hundred times. Now forasmuch as that this is a Cause, +which being added, we adde also the Effect, and being removed, it is +removed; and by augmenting or lessening the length or breadth in any +manner, the effect of going, or not going to the bottom, is not added +or removed: I conclude, that the greatness and smalness of the +Superficies hath no influence upon the Natation or Submersion. And +that the proportion of the Altitude of the Ramparts of Water, to the +Altitude of the Solid, being constituted in the manner aforesaid, the +greatness or smalness of the Superficies, makes not any variation, is +manifest from that which hath been above demonstrated, and from this, +that, _The Prisms and Cylinders which have the same Base, are in +proportion to one another as their heights._ Whence Cylinders or +Prismes[76], namely, the Board, be they great or little, so that they be +all of equall thickness, have the same proportion to their +Conterminall Air, which hath for Base the said Superficies of the +Board, and for height the Ramparts of water; so that alwayes of that +Air, and of the Board, Solids, are compounded, that in Gravity equall +a Mass of water equall to the Mass of the Solids, compounded of Air, +and of the Board: whereupon all the said Solids do in the same manner +continue afloat. We will conclude in the third place, that, + + [76] Prismes and Cylinders having the same Base, are to one + another as their heights. + + + + +THEOREME. IX. + + [Sidenote: All Figures of all Matters, float by hep of the + Rampart replenished with Air, and some but only touch the water.] + + _All sorts of Figures of whatsoever Matter, albeit more grave than + the Water, do by Benefit of the said Rampart, not only float, but + some Figures, though of the gravest Matter, do stay wholly above + Water, wetting only the inferiour Surface that toucheth the + Water._ + + +And these shall be all Figures, which from the inferiour Base upwards, +grow lesser and lesser; the which we shall exemplifie for this time in +Piramides or Cones, of which Figures the passions are common. We will +demonstrate therefore, that, + + _It is possible to form a Piramide, of any whatsoever Matter + preposed, which being put with its Base upon the Water, rests not + only without submerging, but without wetting it more then its + Base._ + +For the explication of which it is requisite, that we first +demonstrate the subsequent Lemma, namely, that, + + + + +LEMMA II. + + [Sidenote: Solids whose Masses are in contrary proportion to + their Specifick Gravities are equall in absolute Gravity.] + + _Solids whose Masses answer in proportion contrarily to their + Specificall Gravities, are equall in Absolute Gravities._ + + +[Illustration] + +Let A C and B be two Solids, and let the Mass A C be to the Mass B, +as the Specificall Gravity of the Solid B, is to the Specificall +Gravity of the Solid A C: I say, the Solids A C and B are equall in +absolute weight, that is, equally grave. For if the Mass A C be equall +to the Mass B, then, by the Assumption, the Specificall Gravity of B, +shall be equall to the Specificall Gravity of A C, and being equall in +Mass, and of the same Specificall Gravity they shall absolutely weigh +one as much as another. But if their Masses shall be unequall, let the +Mass A C be greater, and in it take the part C, equall to the Mass B. +And, because the Masses B and C are equall; the Absolute weight of B, +shall have the same proportion to the Absolute weight of C, that the +Specificall Gravity of B, hath to the Specificall Gravity of C; or of +C A, which is the same _in specie_: But look what proportion the +Specificall Gravity of B, hath to the Specificall Gravity of C A, the +like proportion, by the Assumption, hath the Mass C A, to the Mass B, +that is, to the Mass C: Therefore, the absolute weight of B, to the +absolute weight of C, is as the Mass A C to the Mass C: But as the +Mass A C, is to the Mass C, so is the absolute weight of A C, to the +absolute weight of C: Therefore the absolute weight of B, hath the +same proportion to the absolute weight of C, that the absolute weight +of A C, hath to the absolute weight of C: Therefore, the two Solids A +C and B are equall in absolute Gravity: which was to be demonstrated. +Having demonstrated this, I say, + + + + +THEOREME X. + + [Sidenote: There may be Cones and Piramides of any Matter, which + demitted into the water, rest only their Bases.] + + _That it is possible of any assigned Matter, to form a Piramide or + Cone upon any Base, which being put upon the Water shall not + submerge, nor wet any more than its Base._ + + +[Illustration] + +Let the greatest possible Altitude of the Rampart be the Line D B, +and the Diameter of the Base of the Cone to be made of any Matter +assigned B C, at right angles to D B: And as the Specificall Gravity +of the Matter of the Piramide or Cone to be made, is to the +Specificall Gravity of the water, so let the Altitude of the Rampart D +B, be to the third part of the Piramide or Cone A B C, described upon +the Base, whose Diameter is B C: I say, that the said Cone A B C, and +any other Cone, lower then the same, shall rest upon the Surface of +the water B C without sinking. Draw D F parallel to B C, and suppose +the Prisme or Cylinder E C, which shall be tripple to the Cone A B C. +And, because the Cylinder D C hath the same proportion to the Cylinder +C E, that the Altitude D B, hath to the Altitude B E: But the Cylinder +C E, is to the Cone A B C, as the Altitude E B is to the third part of +the Altitude of the Cone: Therefore, by Equality of proportion, the +Cylinder D C is to the Cone A B C, as D B is to the third part of the +Altitude B E: But as D B is to the third part of B E, so is the +Specificall Gravity of the Cone A B C, to the Specificall Gravity of +the water: Therefore, as the Mass of the Solid D C, is to the Mass of +the Cone A _B_ C, so is the Specificall Gravity of the said Cone, to +the Specificall Gravity of the water: Therefore, by the precedent +Lemma, the Cone A B C weighs in absolute Gravity, as much as a Mass of +Water equall to the Mass D C: But the water which by the imposition of +the Cone A B C, is driven out of its place, is as much as would +precisely lie in the place D C, and is equall in weight to the Cone +that displaceth it: Therefore, there shall be an _Equilibrium_, and +the Cone shall rest without farther submerging. And its manifest, + + +COROLARY I. + + [Sidenote: Amongst Cones of the same Base, those of least + Altitude shall sink the least.] + + _That making upon the same Basis, a Cone of a less Altitude, it + shall be also less grave, and shall so much the more rest without + Submersion._ + + +COROLARY II. + + [Sidenote: There may be Cones and Piramides of any Matter, which + demitted with the Point downwards do float atop.] + + _It is manifest, also, that one may make Cones and Piramids of any + Matter whatsoever, more grave than the water, which being put + into the water, with the Apix or Point downwards, rest without + Submersion._ + +Because if we reassume what hath been above demonstrated, of Prisms +and Cylinders, and that on Bases equall to those of the said +Cylinders, we make Cones of the same Matter, and three times as high +as the Cylinders, they shall rest afloat, for that in Mass and Gravity +they shall be equall to those Cylinders, and by having their Bases +equall to those of the Cylinders, they shall leave equall Masses of +Air included within the Ramparts. This, which for Example sake hath +been demonstrated, in Prisms, Cylinders, Cones and Piramids, might be +proved in all other Solid Figures, but it would require a whole Volume +(such is the multitude and variety of their Symptoms and Accidents) to +comprehend the particuler demonstration of them all, and of their +severall Segments: but I will to avoid prolixity in the present +Discourse, content my self, that by what I have declared every one of +ordinary Capacity may comprehend, that there is not any Matter so +grave, no not Gold it self, of which one may not form all sorts of +Figures, which by vertue of the superiour Air adherent to them, and +not by the Waters Resistance of Penetration, do remain afloat, so that +they sink not. Nay, farther, I will shew, for removing that Error, +that, + + + + +THEOREME XI. + + [Sidenote: A Piramide or Cone, demitted with the Point downwards + shal swim, with its Base downward shall sink.] + + _A Piramide or Cone put into the Water, with the Point downward + shall swimme, and the same put with the Base downwards shall + sinke, and it shall be impossible to make it float._ + + +Now the quite contrary would happen, if the difficulty of Penetrating +the water, were that which had hindred the descent, for that the said +Cone is far apter to pierce and penetrate with its sharp Point, than +with its broad and spacious Base. + +And, to demonstrate this, let the Cone be _A B C_, twice as grave as +the water, and let its height be tripple to the height of the Rampart +_D A E C_: I say, first, that being put lightly into the water with +the Point downwards, it shall not descend to the bottom: for the +Aeriall Cylinder contained betwixt the Ramparts _D A C E_, is equall +in Mass to the Cone _A B C_; so that the whole Mass of the Solid +compounded of the Air _D A C E_, and of the Cone _A B C_, shall be +double to the Cone _A C B_: And, because the Cone _A B C_ is supposed +to be of Matter double in Gravity to the water, therefore as much +water as the whole Masse _D A B C E_, placed beneath the Levell of the +water, weighs as much as the Cone _A B C_: and, therefore, there shall +be an _Equilibrium_, and the Cone _A B C_ shall descend no lower. Now, +I say farther, that the same Cone placed with the Base downwards, +shall sink to the bottom, without any possibility of returning again, +by any means to swimme. + +[Illustration] + +Let, therefore, the Cone be _A B D_, double in Gravity to the water, +and let its height be tripple the height of the Rampart of water L B: +It is already manifest, that it shall not stay wholly out of the +water, because the Cylinder being comprehended betwixt the Ramparts _L +B D P_, equall to the Cone _A B D_, and the Matter of the Cone, beig +double in Gravity to the water, it is evident that the weight of the +said Cone shall be double to the weight of the Mass of water equall to +the Cylinder _L B D P_: Therefore it shall not rest in this state, but +shall descend. + +[Illustration] + + +COROLARY I. + + [Sidenote: Much less shall the said Cone swim, if one immerge a + part thereof.] + + _I say farther; that much lesse shall the said Cone stay afloat, if + one immerge a part thereof._ + +Which you may see, comparing with the water as well the part that +shall immerge as the other above water. Let us therefore of the Cone A +B D, submergeth part N T O S, and advance the Point N S F above water. +The Altitude of the Cone F N S, shall either be more than half the +whole Altitude of the Cone F T O, or it shall not be more: if it shall +be more than half, the Cone F N S shall be more than half of the +Cylinder E N S C: for the Altitude of the Cone F N S, shall be more +than Sesquialter of the Altitude of the Cylinder E N S C: And, because +the Matter of the Cone is supposed to be double in Specificall Gravity +to the water, the water which would be contained within the Rampart E +N S C, would be less grave absolutely than the Cone F N S; so that the +whole Cone F N S cannot be sustained by the Rampart: But the part +immerged N T O S, by being double in Specificall Gravity to the water, +shall tend to the bottom: Therefore, the whole _C_one F T O, as well +in respect of the part submerged, as the part above water shall +descend to the bottom. But if the Altitude of the Point F N S, shall +be half the Altitude of the whole Cone F T O, the same Altitude of the +said Cone F N S shall be Sesquialter to the Altitude E N: and, +therefore, E N S C shall be double to the Cone F N S; and as much +water in Mass as the _C_ylinder E N S C, would weigh as much as the +part of the _C_one F N S. But, because the other immerged part N T O +S, is double in Gravity to the water, a Mass of water equall to that +compounded of the _C_ylinder E N S C, and of the Solid N T O S, shall +weigh less than the _C_one F T O, by as much as the weight of a Mass +of water equall to the Solid N T O S: Therefore, the _C_one sha{l}l +also descend. Again, because the Solid N T O S, is septuple to the +Cone F N S, to which the _C_ylinder E S is double, the proportion of +the Solid N T O S, shall be to the _C_ylinder E N S C, as seaven to +two: Therefore, the whole Solid compounded of the _C_ylinder E N S C, +and of the Solid N T O S, is much less than double the Solid N T O S: +Therefore, the single Solid N T O S, is much graver than a Mass of +water equall to the Mass, compounded of the _C_ylinder E N S C, and of +N T O S. + + +COROLARY II. + + [Sidenote: Part of the Cones towards the Cuspis removed, it shall + still sink.] + + _From whence it followeth, that though one should remove and take + away the part of the Cone F N S, the sole remainder N T O S would + go to the bottom._ + + +COROLARY III. + + [Sidenote: The more the Cone is immerged, the more impossible is + its floating.] + + _And if we should more depress the Cone F T O, it would be so much + the more impossible that it should sustain it self afloat, the + part submerged N T O S still encreasing, and the Mass of Air + contained in the Rampart diminishing, which ever grows less, the + more the Cone submergeth._ + +That Cone, therefore, that with its Base upwards, and its _Cuspis_ +downwards doth swimme, being dimitted with its Base downward must of +necessity sinke. They have argued farre from the truth, therefore, who +have ascribed the cause of Natation to waters resistance of Division, +as to a passive principle, and to the breadth of the Figure, with +which the division is to be made, as the Efficient. + +I come in the fourth place, to collect and conclude the reason of +that which I have proposed to the Adversaries, namely, + + + + +THEOREME XII. + + [Sidenote: Solids of any Figure & greatnesse, that naturally + sink, may by help of the Air in the Rampart swimme.] + + _That it is possible to fo{r}m Solid Bodies, of what Figure and + greatness soever, that of their own Nature goe to the Bottome; + But by the help of the Air contained in the Rampart, rest without + submerging._ + + +[Illustration] + +The truth of this Proposition is sufficiently manifest in all those +Solid Figures, that determine in their uppermost part in a plane +Superficies: for making such Figures of some Matter specifically as +grave as the water, putting them into the water, so that the whole +Mass be covered, it is manifest, that they shall rest in all places, +provided, that such a Matter equall in weight to the water, may be +exactly adjusted: and they shall by consequence, rest or lie even with +the Levell of the water, without making any Rampart. If, therefore, in +respect of the Matter, such Figures are apt to rest without +submerging, though deprived of the help of the Rampart, it is +manifest, that they may admit so much encrease of Gravity, (without +encreasing their Masses) as is the weight of as much water as would be +contained within the Rampart, that is made about their upper plane +Surface: by the help of which being sustained, they shall rest afloat, +but being bathed, they shall descend, having been made graver than the +water. In Figures, therefore, that determine above in a plane, we may +cleerly comprehend, that the Rampart added or removed, may prohibit or +permit the descent: but in those Figures that go lessening upwards +towards the top, some Persons may, and that not without much seeming +Reason, doubt whether the same may be done, and especially by those +which terminate in a very acute Point, such as are your Cones and +small Piramids. Touching these, therefore, as more dubious than the +rest, I will endeavour to demonstrate, that they also lie under the +same Accident of going, or not going to the Bottom, be they of any +whatever bigness. Let therefore the Cone be A B D, made of a matter +specifically as grave as the water; it is manifest that being put all +under water, it shall rest in all places (alwayes provided, that it +shall weigh exactly as much as the water, which is almost impossible +to effect) and that any small weight being added to it, it shall sink +to the bottom: but if it shall descend downwards gently, I say, that +it shall make the Rampart E S T O, and that there shall stay out of +the water the point A S T, tripple in height to the Rampart E S: which +is manifest, for the Matter of the Cone weighing equally with the +water, the part submerged _S B D T_, becomes indifferent to move +downwards or upwards; and the Cone _A S T_, being equall in Mass to +the water that would be contained in the concave of the Rampart _E S T +O_, shall be also equall unto it in Gravity: and, therefore, there +shall be a perfect _Equilibrium_, and, consequently, a Rest. Now here +ariseth a doubt, whether the Cone _A B D_ may be made heavier, in such +sort, that when it is put wholly under water, it goes to the bottom, +but yet not in such sort, as to take from the Rampart the vertue of +sustaining it that it sink not, and, the reason of the doubt is this: +that although at such time as the Cone _A B D_ is specifically as +grave as the water, the Rampart _E S T O_ sustaines it, not only when +the point _A S T_ is tripple in height to the Altitude of the Rampart +_E S_, but also when a lesser part is above water; [for although in +the Descent of the Cone the Point _A S T_ by little and little +diminisheth, and so likewise the Rampart _E S T O_, yet the Point +diminisheth in greater proportion than the Rampart, in that it +diminisheth according to all the three Dimensions, but the Rampart +according to two only, the Altitude still remaining the same; or, if +you will, because the Cone _S {A} T_ goes diminishing, according to +the proportion of the cubes of the Lines that do successively become +the Diameters of the Bases of emergent Cones, and the Ramparts +diminish according to the proportion of the Squares of the same Lines; +whereupon the proportions of the Points are alwayes Sesquialter of the +proportions of the Cylinders, contained within the Rampart; so that +if, for Example, the height of the emergent Point were double, or +equall to the height of the Rampart, in these cases, the Cylinder +contained within the Rampart, would be much greater than the said +Point, because it would be either sesquialter or tripple, by reason of +which it would perhaps serve over and above to sustain the whole Cone, +since the part submerged would no longer weigh any thing;] yet, +nevertheless, when any Gravity is added to the whole Mass of the Cone, +so that also the part submerged is not without some excesse of Gravity +above the Gravity of the water, it is not manifest, whether the +Cylinder contained within the Rampart, in the descent that the Cone +shall make, can be reduced to such a proportion unto the emergent +Point, and to such an excesse of Mass above the Mass of it, as to +compensate the excesse of the Cones Specificall Gravity above the +Gravity of the water: and the Scruple ariseth, because that howbeit in +the descent made by the Cone, the emergent Point _A S T_ diminisheth, +whereby there is also a diminution of the excess of the Cones Gravity +above the Gravity of the water, yet the case stands so, that the +Rampart doth also contract it self, and the Cylinder contained in it +doth deminish. Nevertheless it shall be demonstrated, how that the +Cone _A B D_ being of any supposed bignesse, and made at the first of +a Matter exactly equall in Gravity to the Water, if there may be +affixed to it some Weight, by means of which i{t} may descend to the +bottom, when submerged under water, it may also by vertue of the +Rampart stay above without sinking. + +[Illustration] + +[Illustration] + +Let, therefore, the Cone _A B D_ be of any supposed greatnesse, and +alike in specificall Gravity to the water. It is manifest, that being +put lightly into the water, it shall rest without descending; and it +shall advance above water, the Point _A S T_, tripple in height to the +height of the Rampart _E S_: Now, suppose the Cone _A B D_ more +depressed, so that it advance above water, only the Point _A I R_, +higher by half than the Point _A S T_, with the Rampart about it _C I +R N_. And, because, the Cone _A B D_ is to the Cone _A I R_, as the +cube of the Line _S T_ is to the cube of the Line _I R_, but the +Cylinder _E S T O_, is to the Cylinder _C I R N_, as the Square of _S +T_ to the Square of _I R_, the Cone _A S T_ shall be Octuple to the +Cone _A I R_, and the Cylinder _E S T O_, quadruple to the Cylinder _C +I R N_: But the Cone _A S T_, is equall to the Cylinder _E S T O_: +Therefore, the Cylinder _C I R N_, shall be double to the Cone _A I +R_: and the water which might be contained in the Rampart _C I R N_, +would be double in Mass and in Weight to the Cone _A I R_, and, +therefore, would be able to sustain the double of the Weight of the +Cone _A I R_: Therefore, if to the whole Cone _A B D_, there be added +as much Weight as the Gravity of the Cone _A I R_, that is to say, the +eighth part of the weight of the Cone _A S T_, it also shall be +sustained by the Rampart _C I R N_, but without that it shall go to +the bottome: the Cone _A B D_, being, by the addition of the eighth +part of the weight of the Cone _A S T_, made specifically more grave +than the water. But if the Altitude of the Cone _A I R_, were two +thirds of the Altitude of the Cone _A S T_, the Cone _A S T_ would be +to the Cone _A I R_, as twenty seven to eight; and the Cylinder _E S T +O_, to the Cylinder _C I R N_, as nine to four, that is, as twenty +seven to twelve; and, therefore, the Cylinder _C I R N_, to the Cone +_A I R_, as twelve to eight; and the excess of the Cylinder _C I R N_, +above the Cone _A I R_, to the Cone _A S T_, as four to twenty seven: +therefore if to the Cone _A B D_ be added so much weight as is the +four twenty sevenths of the weight of the Cone _A S T_, which is a +little more then its seventh part, it also shall continue to swimme, +and the height of the emergent Point shall be double to the height of +the Rampart. This that hath been demonstrated in Cones, exactly holds +in Piramides, although the one or the other should be very sharp in +their Point or Cuspis[77]: From whence we conclude, that the same Accident +shall so much the more easily happen in all other Figures, by how much +the less sharp the Tops shall be, in which they determine, being +assisted by more spacious Ramparts. + + [77] Natatio{n} easiest effected in Figures broad toward the top. + + + + +THEOREME XIII. + + [Sidenote: All Figures sink or swim, upon bathing or not bathing + of their tops.] + + _All Figures, therefore, of whatever greatnesse, may go, and not + go, to the Bottom, according as their Sumities or Tops shall be + bathed or not bathed._ + + +And this Accident being common to all sorts of Figures, without +exception of so much as one. Figure hath, therefore, no part in the +production of this Effect, of sometimes sinking, and sometimes again +not sinking, but only the being sometimes conjoyned to, and sometimes +seperated from, the supereminent Air: which cause, in fine, who so +shall rightly, and, as we say, with both his Eyes, consider this +business, will find that it is reduced to, yea, that it really is the +same with, the true, Naturall and primary cause of Natation or +Submersion; to wit, the excess or deficiency of the Gravity of the +water, in relation to the Gravity of that Solid Magnitude, that is +demitted into the water. For like as a Plate of Lead, as thick as the +back of a Knife, which being put into the water by it self alone goes +to the bottom, if upon it you fasten a piece of Cork four fingers +thick, doth continue afloat, for that now the Solid that is demitted +in the water, is not, as before, more grave than the water, but less, +so the Board of Ebony, of its own nature more grave than water; and, +therefore, descending to the bottom, when it is demitted by it self +alone into the water, if it shall be put upon the water, conjoyned +with an Expanded vail of Air, that together with the Ebony doth +descend, and that it be such, as that it doth make with it a compound +less grave than so much water in Mass, as equalleth the Mass already +submerged and depressed beneath the Levell of the waters Surface, it +shall not descend any farther, but shall rest, for no other than the +universall and most common cause, which is that Solid Magnitudes, less +grave _in specie_ than the water, go not to the bottom. + +So that if one should take a Plate of Lead, as for Example, a finger +thick, and an handfull broad every way, and should attempt to make it +swimme, with putting it lightly on the water, he would lose his +Labour, because that if it should be depressed an Hairs breadth beyond +the possible Altitude of the Ramparts of water, it would dive and +sink; but if whilst it is going downwards, one should make certain +Banks or Ramparts about it, that should hinder the defusion of the +water upon the said Plate, the which Banks should rise so high, as +that they might be able to contain as much water, as should weigh +equally with the said Plate, it would, witho{u}t all Question, descend +no lower, but would rest, as being sustained by vertue of the Air +contained within the aforesaid Ramparts: and, in short, there would be +a Vessell by this means formed with the bottom of Lead. But if the +thinness of the Lead shall be such, that a very small height of +Rampart would suffice to contain so much Air, as might keep it afloat, +it shall also rest without the Artificiall Banks or Ramparts, but yet +not without the Air, because the Air by it self makes Banks sufficient +for a small height, to resist the Superfusion of the water: so that +that which in this case swimmes, is as it were a Vessell filled with +Air, by vertue of which it continueth afloat. + +I will, in the last place, with an other Experime{n}t, attempt to +remove all difficulties, if so be there should yet be any doubt left +in any one, touching the opperation of this [E]Continuity of the Air, +with the thin Plate which swims, and afterwards put an end to this +part of my discourse. + + [E] Or rather Contiguity, + +I suppose my self to be questioning with some of my Oponents. + +Whether Figure have any influence upon the encrease or diminution of +the Resistance in any Weight against its being raised in the Air[78]; and +I suppose, that I am to maintain the Affirmative, asserting that a +Mass of Lead, reduced to the Figure of a Ball, shall be raised with +less force, then if the same had been made into a thinne and broad +Plate, because that it in this spacious Figure, hath a great quantity +of Air to penetrate, and in that other, more compacted and contracted +very little: and to demonstrate the truth of such my Opinion, I will +hang in a small thred first the Ball or Bullet, and put that into the +water, tying the thred that upholds it to one end of the Ballance that +I hold in the Air, and to the other end I by degrees adde so much +Weight, till that at last it brings up the Ball of Lead out of the +water: to do which, suppose a Gravity of thirty Ounces sufficeth; I +afterwards reduce the said Lead into a flat and thinne Plate, the +which I likewise put into the water, suspended by three threds, which +hold it parallel to the Surface of the water, and putting in the same +manner, Weights to the other end, till such time as the Plate comes to +be raised and drawn out of the water: I finde that thirty six ounces +will not suffice to seperate it from the water, and raise it thorow +the Air: and arguing from this Experiment, I affirm, that I have fully +demonstrated the truth of my Proposition. Here my Oponents desires me +to look down, shewing me a thing which I had not before observed, to +wit, that in the Ascent of the Plate out of the water, it draws after +it another Plate (_if I may so call it_) of water, which before it +divides and parts from the inferiour Surface of the Plate of Lead, is +raised above the Levell of the other water, more than the thickness of +the back of a Knife: Then he goeth to repeat the Experiment with the +Ball, and makes me see, that it is but a very small quantity of water, +which cleaves to its compacted and contracted Figure: and then he +subjoynes, that its no wonder, if in seperating the thinne and broad +Plate from the water, we meet with much greater Resistance, than in +seperating the Ball, since together with the Plate, we are to raise a +great quantity of water, which occurreth not in the Ball: He telleth +me moreover, how that our Question is, whether the Resistance of +Elevation be greater in a dilated Plate of Lead, than in a Ball, and +not whether more resisteth a Plate of Lead with a great quantity of +water, or a Ball with a very little water: He sheweth me in the close, +that the putting the Plate and the Ball first into the water, to make +proofe thereby of their Resistance in the Air, is besides our case, +which treats of Elivating in the Air, and of things placed in the Air, +and not of the Resistance that is made in the Confines of the Air and +water, and by things which are part in Air and part in water: and +lastly, they make me feel with my hand, that when the thinne Plate is +in the Air, and free from the weight of the water, it is raised with +the very same Force that raiseth the Ball. Seeing, and understanding +these things, I know not what to do, unless to grant my self +convinced, and to thank such a Friend, for having made me to see that +which I never till then observed: and, being advertised by this same +Accident, to tell my Adversaries, that our Question is, whether a +Board and a Ball of Ebony, equally go to the bottom in water, and not +a Ball of Ebony and a Board of Ebony, joyned with another flat Body of +Air: and, farthermore, that we speak of sinking, and not sinking to +the bottom, in water, and not of that which happeneth in the Confines +of the water and Air to Bodies that be part in the Air, and part in +the water; nor much less do we treat of the greater or lesser Force +requisite in seperating this or that Body from the Air; not omitting +to tell them, in the last place, that the Air doth resist, and +gravitate downwards in the water, just so much as the water (if I may +so speak) gravitates and resists upwards in the Air, and that the same +Force is required to sinke a Bladder under water, that is full of Air, +as to raise it in the Air, being full of water, removing the +consideration of the weight of that Filme or Skinne, and considering +the water and the Air only. And it is likewise true, that the same +Force is required to sink a Cup or such like Vessell under water, +whilst it is full of Air, as to raise it above the Superficies of the +water, keeping it with the mouth downwards; whilst it is full of +water, which is constrained in the same manner to follow the Cup which +contains it, and to rise above the other water into the Region of the +Air, as the Air is forced to follow the same Vessell under the Surface +of the water, till that in this c{a}se the water, surmounting the +brimme of the Cup, breaks in, driving thence the Air, and in that +case, the said brimme coming out of the water, and arriving to the +Confines of the Air, the water falls down, and the Air sub-enters to +fill the cavity of the Cup: upon which ensues, that he no less +transgresses the Articles of the _Convention_, who produceth a Plate +conjoyned with much Air, to see if it descend to the bottom in water, +then he that makes proof of the Resistance against Elevation in Air +with a Plate of Lead, joyned with a like quantity of water. + + [78] An Experiment of the operation of Figures, in encreasing or + lessening of the Airs Resistance of Division. + + [Sidenote: _Aristotles_ opinion touching the Operation of Figure + examined.] + +I have said all that I could at present think of, to maintain the +Assertion I have undertook. It remains, that I examine that which +_Aristotle_ hath writ of this matter towards the end of his Book De +Cælo[79]; wherein I shall note two things: the one that it being true as +hath been demonstrated, that Figure hath nothing to do about the +moving or not moving it self upwards or downwards, its seemes that +_Aristotle_ at his first falling upon this Speculation, was of the +same opinion, as in my opinion may be collected from the examination +of his words. 'Tis true, indeed, that in essaying afterwards to render +a reason of such effect, as not having in my conceit hit upon the +right, (which in the second place I will examine) it seems that he is +brought to admit the largenesse of Figure, to be interessed in this +operation. As to the first particuler, hear the precise words of +_Aristotle_. + + [79] _Aristot. de Cælo_ Lib. 4. Cap 6. + +_Figures are not the Causes of moving simply upwards or downwards, but +of moving more slowly or swiftly[80][81], and by what means this comes to +pass, it is not difficult to see._ + + [80] _Aristotle_ makes not Figure the cause of Motion absolutely, + but of swift or slow motion, + + [81] Lib. 4. Cap. 6: Text. 42. + +Here first I note, that the terms being four, which fall under the +present consideration, namely, Motion, Rest, Slowly and Swiftly: And +_Aristotle_ naming figures as Causes of Tardity and Velocity, +excluding them from being the Cause of absolute and simple Motion, it +seems necessary, that he exclude them on the other side, from being +the Cause of Rest, so that his meaning is this. Figures are not the +Causes of moving or not moving absolutely, but of moving quickly or +slowly: and, here, if any should say the mind of _Aristotle_ is to +exclude Figures from being Causes of Motion, but yet not from being +Causes of Rest, so that the sence would be to remove from Figures, +there being the Causes of moving simply, but yet not there being +Causes of Rest, I would demand, whether we ought with _Aristotle_ to +understand, that all Figures universally, are, in some manner, the +causes of Rest in those Bodies, which otherwise would move, or else +some particular Figures only, as for Example, broad and thinne +Figures: If all indifferently, then every Body shall rest: because +every Body hath some Figure, which is false; but if some particular +Figures only may be in some manner a Cause of Rest, as, for Example, +the broad, then the others would be in some manner the Causes of +Motion: for if from seeing some Bodies of a contracted Figure move, +which after dilated into Plates rest, may be inferred, that the +Amplitude of Figure hath a part in the Cause of that Rest; so from +seeing such like Figures rest, which afterwards contracted move, it +may with the same reason be affirmed, that the united and contracted +Figure, hath a part in causing Motion, as the remover of that which +impeded it: The which again is directly opposite to what _Aristotle_ +saith, namely, that Figures are not the Causes of Motion. Besides, if +_Aristotle_ had admitted and not excluded Figures from being Causes of +not moving in some Bodies, which moulded into another Figure would +move, he would have impertinently propounded in a dubitative manner, +in the words immediately following, whence it is, that the large and +thinne Plates of Lead or Iron, rest upon the water, since the Cause +was apparent, namely, the Amplitude of Figure. Let us conclude, +therefore, that the meaning of _Aristotle_ in this place is to affirm, +that Figures are not the Causes of absolutely moving or not moving, +but only of moving swiftly or slowly: which we ought the rather to +believe, in regard it is indeed a most true conceipt and opinion. Now +the mind of _Aristotle_ being such, and appearing by consequence, +rather contrary at the first sight, then favourable to the assertion +of the Oponents, it is necessary, that their Interpretation be not +exactly the same with that, but such, as being in part understood by +some of them, and in part by others, was set down: and it may easily +be indeed so, being an Interpretation consonent to the sence of the +more famous Interpretors, which is, that the Adverbe _Simply_ or +_Absolutely_, put in the Text, ought not to be joyned to the Verbe to +_Move_, but with the Noun _Causes_: so that the purport of +_Aristotles_ words, is to affirm, That Figures are not the Causes +absolutely of moving or not moving, but yet are Causes _Secundum +quid_, _viz._ in some sort; by which means, they are called Auxiliary +and Concomitant Causes: and this Proposition is received and asserted +as true by _Signor Buonamico Lib. 5. Cap. 28._ where he thus writes. +_There are other Causes concomitant, by which some things float, and +others sink, among which the Figures of Bodies hath the first place_, +&c. + +Concerning this Proposition, I meet with many doubts and difficulties, +for which me thinks the words of _Aristotle_ are not capable of such a +construction and sence, and the difficulties are these. + +First in the order and disposure of the words of _Aristotle_, the +particle _Simpliciter_, or if you will _absoluté_, is conjoyned with +the Verb _to move_, and seperated from the Noun _Causes_, the which is +a great presumption in my favour, seeing that the writing and the Text +saith, Figures are not the Cause of moving simply upwards or +downwards, but of quicker or slower Motion: and, saith not, Figures +are not simply the Causes of moving upwards or downwards, and when the +words of a Text receive, transposed, a sence different from that which +they sound, taken in the order wherein the Author disposeth them, it +is not convenient to inverte them. And who will affirm that +_Aristotle_ desiring to write a Proposition, would dispose the words +in such sort, that they should import a different, nay, a contrary +sence? contrary, I say, because understood as they are written; they +say, that Figures are not the Causes of Motion, but inverted, they +say, that Figures are the Causes of Motion, &c. + +Moreover, if the intent of _Aristotle_ had been to say, that Figures +are not simply the Causes of moving upwards or downwards, but only +Causes _Secundum quid_, he would not have adjoyned those words, _but +they are Causes of the more swift or slow Motion_; yea, the subjoining +this would have been not only superfluous but false, for that the +whole tenour of the Proposition would import thus much. Figures are +not the absolute Causes of moving upwards or downwards, but are the +absolute Cause of the swift or slow Motion; which is not true: because +the primary Causes of greater or lesser Velocity, are by _Aristotle_ +in the 4th of his _Physicks_, _Text. 71._ attributed to the greater or +lesser Gravity of Moveables, compared among themselves, and to the +greater or lesser Resistance of the _Medium's_, depending on their +greater or less Crassitude: and these are inserted by _Aristotle_ as +the primary Causes; and these two only are in that place nominated: +and Figure comes afterwards to be considered, _Text. 74._ rather as an +Instrumentall Cause of the force of the Gravity, the which divides +either with the Figure, or with the _Impetus_; and, indeed, Figure by +it self without the force of Gravity or Levity, would opperate +nothing. + +I adde, that if _Aristotle_ had an opinion that Figure had been in +some sort the Cause of moving or not moving, the inquisition which he +makes immediately in a doubtfull manner, whence it comes, that a Plate +of Lead flotes, would have been impertinent; for if but just before he +had said, that Figure was in a certain sort the Cause of moving or not +moving, he needed not to call in Question, by what Cause the Plate of +Lead swims, and then ascribing the Cause to its Figure; and framing a +discourse in this manner. Figure is a Cause _Secundum quid_ of not +sinking: but, now, if it be doubted, for what Cause a thin Plate of +Lead goes not to the bottom; it shall be answered, that that proceeds +from its Figure: a discourse which would be indecent in a Child, much +more in _Aristotle_; For where is the occasion of doubting? And who +sees not, that if _Aristotle_ had held, that Figure was in some sort a +Cause of Natation, he would without the least Hesitation have writ; +That Figure is in a certain sort the Cause of Natation, and therefore +the Plate of Lead in respect of its large and expatiated Figure swims; +but if we take the proposition of _Aristotle_ as I say, and as it is +written, and as indeed it is true, the ensuing words come in very +oppositely, as well in the introduction of swift and slow, as in the +question, which very pertinently offers it self, and would say thus +much. + +Figures are not the Cause of moving or not moving simply upwards or +downwards, but of moving more quickly or slowly: But if it be so, the +Cause is doubtfull, whence it proceeds, that a Plate of Lead or of +Iron broad and thin doth swim, &c. And the occasion of the doubt is +obvious, because it seems at the first glance, that the Figure is the +Cause of this Natation, since the same Lead, or a less quantity, but +in another Figure, goes to the bottom, and we have already affirmed, +that the Figure hath no share in this effect. + +Lastly, if the intent of _Aristotle_ in this place had been to say, +that Figures, although not absolutely, are at least in some measure +the Cause of moving or not moving: I would have it considered, that he +names no less the Motion upwards, than the other downwards: and +because in exemplifying it afterwards, he produceth no other +Experiments than of a Plate of Lead, and Board of Ebony, Matters that +of their own Nature go to the bottom, but by vertue (as our +Adversaries say) of their Figure, rest afloat; it is fit that they +should produce some other Experiment of those Matters, which by their +Nature swims, but retained by their Figure rest at the bottom. But +since this is impossible to be done, we conclude, that _Aristotle_ in +this place, hath not attributed any action to the Figure of simply +moving or not moving. + +But though he hath exquisitely Philosophiz'd, in investigating the +solution of the doubts he proposeth, yet will I not undertake to +maintain, rather various difficulties, that present themselves unto +me, give me occasion of suspecting that he hath not entirely displaid +unto us, the true Cause of the present Conclusion: which difficulties +I will propound one by one, ready to change opinion, whenever I am +shewed, that the Truth is different from what I say; to the confession +whereof I am much more inclinable than to contradiction. + + [Sidenote: _Aristotle_ erred in affirming a Needle dimitted long + wayes to sink.] + +_Aristotle_ having propounded the Question, whence it proceeds, that +broad Plates of Iron or Lead, float or swim; he addeth (as it were +strengthening the occasion of doubting) forasmuch as other things, +less, and less grave, be they round or long, as for instance a Needle +go to the bottom. Now I here doubt, or rather am certain that a Needle +put lightly upon the water, rests afloat, no less than the thin Plates +of Iron or Lead. I cannot believe, albeit it hath been told me, that +some to defend _Aristotle_ should say, that he intends a Needle +demitted not longwayes but endwayes, and with the Point downwards; +nevertheless, not to leave them so much as this, though very weak +refuge, and which in my judgement _Aristotle_ himself would refuse, I +say it ought to be understood, that the Needle must be demitted, +according to the Dimension named by _Aristotle_, which is the length: +because, if any other Dimension than that which is named, might or +ought to be taken, I would say, that even the Plates of Iron and Lead, +sink to the bottom, if they be put into the water edgewayes and not +flatwayes. But because _Aristotle_ saith, broad Figures go not to the +bottom, it is to be understood, being demitted broadwayes: and, +therefore, when he saith, long Figures as a Needle, albeit light, rest +not afloat, it ought to be understood of them when demitted longwayes. + + _Moreover, to say that_ Aristotle _is to be understood of the + Needle demitted with the Point downwards, is to father upon him a + great impertinency; for in this place he saith, that little + Particles of Lead or Iron, if they be round or long as a Needle, do + sink to the bottome; so that by his Opinion, a Particle or small + Grain of Iron cannot swim: and if he thus believed, what a great + folly would it be to subjoyn, that neither would a Needle demitted + endwayes swim? And what other is such a Needle, but many such like + Graines accumulated one upon another? It was too unworthy of such a + man to say, that one single Grain of Iron could not swim, and that + neither can it swim, though you put a hundred more upon it._ + +Lastly, either _Aristotle_ believed, that a Needle demitted longwayes +upon the water, would swim, or he believed that it would not swim: If +he believed it would not swim, he might well speak as indeed he did; +but if he believed and knew that it would float, why, together with +the dubious Problem of the Natation of broad Figures, though of +ponderous Matter, hath he not also introduced the Question; whence it +proceeds, that even long and slender Figures, howbeit of Iron or Lead +do swim? And the rather, for that the occasion of doubting seems +greater in long and narrow Figures, than in broad and thin, as from +_Aristotles_ not having doubted of it, is manifested. + +No lesser an inconvenience would they fasten upon _Aristotle_, who in +his defence should say, that he means a Needle pretty thick, and not a +small one; for take it for granted to be intended of a small one; and +it shall suffice to reply, that he believed that it would swim; and I +will again charge him with having avoided a more wonderfull and +intricate Probleme, and introduced the more facile and less +wonderfull. + +We say freely therefore, that _Aristotle_ did hold, that only the +broad Figure did swim, but the long and slender, such as a Needle, +not. The which nevertheless is false, as it is also false in round +Bodies: because, as from what hath been predemonstrated, may be +gathered, little Balls of Lead and Iron, do in like manner swim. + + [Sidenote: _Aristotle_ affirmeth some Bodies volatile for their + Minuity, Text. 42.] + +He proposeth likewise another Conclusion, which likewise seems +different from the truth, and it is, That some things, by reason of +their littleness fly in the Air, as the small dust of the Earth, and +the thin leaves of beaten Gold: but in my Opinion, Experience shews +us, that that happens not only in the Air, but also in the water, in +which do descend, even those Particles or Atomes of Earth, that +disturbe it, whose minuity is such, that they are not deservable, save +only when they are many hundreds together. Therefore, the dust of the +Earth, and beaten Gold, do not any way sustain themselves in the Air, +but descend downwards, and only fly to and again in the same, when +strong Windes raise them, or other agitations of the Air commove them: +and this also happens in the commotion of the water, which raiseth its +Sand from the bottom, and makes it muddy. But _Aristotle_ cannot mean +this impediment of the commotion, of which he makes no mention, nor +names other than the lightness of such Minutiæ or Atomes, and the +Resistance of the Crassitudes of the Water and Air, by which we see, +that he speakes of a calme, and not disturbed and agitated Air: but in +that case, neither Gold nor Earth, be they never so small, are +sustained, but speedily descend. + + [Sidenote: _Democritus_ placed the Cause of Natation in certain + fiery Atomes.] + +He passeth next to confute _Democritus_[82], which, by his Testimony would +have it, that some Fiery Atomes, which continually ascend through the +water, do spring upwards, and sustain those grave Bodies, which are +very broad, and that the narrow descend to the bottom, for that but a +small quantity of those Atomes, encounter and resist them. + + [82] _Aristot. De Cælo_ lib. 4. cap. 6. text. 43. + +I say, _Aristotle_ confutes this position[83], saying, that that should +much more occurre in the Air, as the same _Democritus_ instances +against himself, but after he had moved the objection, he slightly +resolves it, with saying, that those Corpuscles which ascend in the +Air, make not their _Impetus_ conjunctly. Here I will not say, that +the reason alledged by _Democritus_ is true[84], but I will only say, it +seems in my judgement, that it is not wholly confuted by _Aristotle_, +whilst he saith, that were it true, that the calid ascending Atomes, +should sustain Bodies grave, but very broad, it would much more be +done in the Air, than in Water, for that haply in the Opinion of +_Aristotle_, the said calid Atomes ascend with much greater Force and +Velocity through the Air, than through the water. And if this be so, +as I verily believe it is, the Objection of _Aristotle_ in my +judgement seems to give occasion of suspecting, that he may possibly +be deceived in more than one particular: First, because those calid +Atomes, (whether they be Fiery Corpuscles, or whether they be +Exhalations, or in short, whatever other matter they be, that ascends +upwards through the Air) cannot be believed to mount faster through +Air, than through water: but rather on the contrary, they peradventure +move more impetuously through the water, than through the Air, as hath +been in part demonstrated above. And here I cannot finde the reason, +why _Aristotle_ seeing, that the descending Motion of the same +Moveable, is more swift in Air, than in water, hath not advertised us, +that from the contrary Motion, the contrary should necessarily follow; +to wit, that it is more swift in the water, than in the Air: for since +that the Moveable which descendeth, moves swifter through the Air, +than through the water, if we should suppose its Gravity gradually to +diminish, it would first become such, that descending swiftly through +the Air, it would descend but slowly through the water: and then +again, it might be such, that descending in the Air, it should ascend +in the water: and being made yet less grave, it shall ascend swiftly +through the water, and yet descend likewise through the Air: and in +short, before it can begin to ascend, though but slowly through the +Air, it shall ascend swiftly through the water: how then is it true, +that ascending Moveables move swifter through the Air, than through +the water? + + [83] _Democritus_ confuted by _Aristotle_, text 43. + + [84] _Aristotles_ confutation of _Democritus_ refuted by the + Author. + +That which hath made _Aristotle_ believe, the Motion of Ascent to be +swifter in Air, than in water, was first, the having referred the +Causes of slow and quick, as well in the Motion of Ascent, as of +Descent, only to the diversity of the Figures of the Moveable, and to +the more or less Resistance of the greater or lesser Crassitude, or +Rarity of the _Medium_; not regarding the comparison of the Excesses +of the Gravities of the Moveables, and of the _Mediums_: the which +notwithstanding, is the most principal point in this affair: for if +the augmentation and diminution of the Tardity or Velocity, should +have only respect to the Density or Rarity of the _Medium_, every Body +that descends in Air, would descend in water: because whatever +difference is found between the Crassitude of the water, and that of +the Air, may well be found between the Velocity of the same Moveable +in the Air, and some other Velocity: and this should be its proper +Velocity in the water, which is absolutely false. The other occasion +is, that he did believe, that like as there is a positive and +intrinsecall Quality, whereby Elementary Bodies have a propension of +moving towards the Centre of the Earth, so there is another likewise +intrinsecall[85], whereby some of those Bodies have an _Impetus_ of flying +the Centre, and moving upwards: by Vertue of which intrinsecall +Principle, called by him Levity, the Moveables which have that same +Motion more easily penetrate the more subtle _Medium_, than the more +dense: but such a Proposition appears likewise uncertain, as I have +above hinted in part, and as with Reasons and Experiments, I could +demonstrate, did not the present Argument importune me, or could I +dispatch it in few words. + + [85] Lib. 4. Cap. 5. + +The Objection therefore of _Aristotle_ against _Democritus_, whilst he +saith, that if the Fiery ascending Atomes should sustain Bodies grave, +but of a distended Figure, it would be more observable in the Air than +in the water, because such Corpuscles move swifter in that, than in +this, is not good; yea the contrary would evene, for that they ascend +more slowly through the Air: and, besides their moving slowly, they +ascend, not united together, as in the water, but discontinue, and, as +we say, scatter: And, therefore, as _Democritus_ well replyes, +resolving the instance they make not their push or _Impetus_ +conjunctly. + +_Aristotle_, in the second place, deceives himself, whilst he will +have the said grave Bodies to be more easily sustained by the said +Fiery ascending Atomes in the Air than in the Water: not observing, +that the said Bodies are much more grave in that, than in this, and +that such a Body weighs ten pounds in the Air, which will not in the +water weigh 1/2 an ounce; how can it then be more easily sustained in +the Air, than in the Water? + + [Sidenote: _Democritus_ confuted by the Authour.] + +Let us conclude, therefore, that _Democritus_ hath in this particular +better Philosophated than _Aristotle_. But yet will not I affirm, that +_Democritus_ hath reason'd rightly, but I rather say, that there is a +manifest Experiment that overthrows his Reason, and this it is, That +if it were true, that calid ascending Atomes should uphold a Body, +that if they did not hinder, would go to the bottom, it would follow, +that we may find a Matter very little superiour in Gravity to the +water, the which being reduced into a Ball, or other contracted +Figure, should go to the bottom, as encountring but few Fiery Atomes; +and which being distended afterwards into a dilated and thin Plate, +should come to be thrust upwards by the impulsion of a great Multitude +of those Corpuscles, and at last carried to the very Surface of the +water: which wee see not to happen; Experience shewing us, that a Body +_v. gra._ of a Sphericall Figure, which very hardly, and with very +great leasure goeth to the bottom, will rest there, and will also +descend thither, being reduced into whatsoever other distended Figure. +We must needs say then, either that in the water, there are no such +ascending Fiery Atoms, or if that such there be, that they are not +able to raise and lift up any Plate of a Matter, that without them +would go to the bottom: Of which two Positions, I esteem the second to +be true, understanding it of water, constituted in its naturall +Coldness. But if we take a Vessel of Glass, or Brass, or any other +hard matter, full of cold water, within which is put a Solid of a flat +or concave Figure, but that in Gravity exceeds the water so little, +that it goes slowly to the bottom; I say, that putting some burning +Coals under the said Vessel, as soon as the new Fiery Atomes shall +have penetrated the substance of the Vessel, they shall without doubt, +ascend through that of the water, and thrusting against the foresaid +Solid, they shall drive it to the Superficies, and there detain it, as +long as the incursions of the said Corpuscles shall last, which +ceasing after the removall of the Fire, the Solid being abandoned by +its supporters, shall return to the bottom. + +But _Democritus_ notes, that this Cause only takes place when we +treat of raising and sustaining of Plates of Matters, but very little +heavier than the water, or extreamly thin: but in Matters very grave, +and of some thickness, as Plates of Lead or other Mettal, that same +Effect wholly ceaseth: In Testimony of which, let's observe that such +Plates, being raised by the Fiery Atomes, ascend through all the depth +of the water, and stop at the Confines of the Air, still staying under +water: but the Plates of the Opponents stay not, but only when they +have their upper Superficies dry, nor is there any means to be used, +that when they are within the water, they may not sink to the bottom. +The cause, therefore, of the Supernatation of the things of which +_Democritus_ speaks is one, and that of the Supernatation of the +things of which we speak is another. But, returning to _Aristotle_[86], +methinks that he hath more weakly confuted _Democritus_, than +_Democritus_ himself hath done: For _Aristotle_ having propounded the +Objection which he maketh against him, and opposed him with saying, +that if the calid ascendent Corpuscles were those that raised the thin +Plate, much more then would such a Solid be raised and born upwards +through the Air, it sheweth that the desire in _Aristotle_ to detect +_Democritus_, was predominate over the exquisiteness of Solid +Philosophizing: which desire of his he hath discovered in other +occasions, and that we may not digress too far from this place, in the +Text precedent to this Chapter which we have in hand[87]; where he +attempts to confute the same _Democritus_ for that he, not contenting +himself with names only, had essayed more particularly to declare what +things Gravity and Levity were; that is, the Causes of descending and +ascending, (and had introduced Repletion and Vacuity) ascribing this +to Fire, by which it moves upwards, and that to the Earth, by which it +descends; afterwards attributing to the Air more of Fire, and to the +water more of Earth. But _Aristotle_ desiring a positive Cause, even +of ascending Motion, and not as _Plato_, or these others, a simple +negation, or privation, such as Vacuity would be in reference to +Repletion[88], argueth against _Democritus_ and saith: If it be true, as +you suppose, then there shall be a great Mass of water, which shall +have more of Fire, than a small Mass of Air, and a great Mass of Air, +which shall have more of Earth than a little Mass of water, whereby it +would ensue, that a great Mass of Air, should come more swiftly +downwards, than a little quantity of water: But that is never in any +case soever: Therefore _Democritus_ discourseth erroneously. + + [86] _Aristotle_ shews his desire of finding _Democritus_ in an + Error, to exceed that of discovering Truth. + + [87] Cap. 5. Text 41. + + [88] Id. ibid. + +But in my opinion, the Doctrine of _Democritus_ is not by this +allegation overthrown, but if I erre not, the manner of _Aristotle_ +deduction either concludes not, or if it do conclude any thing, it may +with equall force be restored against himself. _Democritus_ will grant +to _Aristotle_, that there may be a great Mass of Air taken, which +contains more Earth, than a small quantity of water, but yet will +deny, that such a Mass of Air, shall go faster downwards than a little +water, and that for many reasons. First, because if the greater +quantity of Earth, contained in the great Mass of Air, ought to cause +a greater Velocity than a less quantity of Earth, contained in a +little quantity of water, it would be necessary, first, that it were +true, that a greater Mass of pure Earth, should move more swiftly than +a less: But this is false, though _Aristotle_ in many places affirms +it to be true: because not the greater absolute, but the greater +specificall Gravity, is the cause of greater Velocity[89]: nor doth a Ball +of Wood, weighing ten pounds, descend more swiftly than one weighing +ten Ounces, and that is of the same Matter: but indeed a Bullet of +Lead of four Ounces, descendeth more swiftly than a Ball of Wood of +twenty Pounds: because the Lead is more _grave in specie_ than the +Wood. Therefore, its not necessary, that a great Mass of Air, by +reason of the much Earth contained in it, do descend more swiftly than +a little Mass of water[90], but on the contrary, any whatsoever Mass of +water, shall move more swiftly than any other of Air, by reason the +participation of the terrene parts _in specie_ is greater in the +water, than in the Air. Let us note, in the second place, how that in +multiplying the Mass of the Air, we not only multiply that which is +therein of terrene, but its Fire also: whence the Cause of ascending, +no less encreaseth, by vertue of the Fire, than that of descending on +the account of its multiplied Earth. It was requisite in increasing +the greatness of the Air, to multiply that which it hath of terrene +only, leaving its Fire in its first state, for then the terrene parts +of the augmented Air, overcoming the terrene parts of the small +quantity of water, it might with more probability have been pretended, +that the great quantity of Air, ought to descend with a greater +_Impetus_, than the little quantity of water. + + [89] The greater Specificall, not the greater absolute Gravity, + is the Cause of Velocity. + + [90] Any Mass of water shal move more swiftly, than any of Air, + and why. + +Therefore, the Fallacy lyes more in the Discourse of _Aristotle_, than +in that of _Democritus_, who with severall other Reasons might oppose +_Aristotle_, and alledge; If it be true, that the extreame Elements be +one simply grave, and the other simply light, and that the mean +Elements participate of the one, and of the other Nature; but the Air +more of Levity, and the water more of Gravity, then there shall be a +great Mass of Air, whose Gravity shall exceed the Gravity of a little +quantity of water, and therefore such a Mass of Air shall descend more +swiftly than that little water: But that is never seen to occurr: +Therefore its not true, that the mean Elements do participate of the +one, and the other quality. This argument is fallacious, no less than +the other against _Democritus_. + +Lastly, _Aristotle_ having said, that if the Position of _Democritus_ +were true, it would follow, that a great Mass of Air should move more +swiftly than a small Mass of water, and afterwards subjoyned, that +that is never seen in any Case: methinks others may become desirous to +know of him in what place this should evene, which he deduceth against +_Democritus_, and what Experiment teacheth us, that it never falls out +so. To suppose to see it in the Element of water, or in that of the +Air is vain, because neither doth water through water, nor Air through +Air move, nor would they ever by any whatever participation others +assign them, of Earth or of Fire: the Earth, in that it is not a Body +fluid, and yielding to the mobility of other Bodies, is a most +improper place and _Medium_ for such an Experiment: _Vacuum_, +according to the same _Aristotle_ himself, there is none, and were +there, nothing would move in it: there remains the Region of Fire, but +being so far distant from us, what Experiment can assure us, or hath +assertained _Aristotle_ in such sort, that he should as of a thing +most obvious to sence, affirm what he produceth in confutation of +_Democritus_, to wit, that a great Mass of Air, is moved no swifter +than a little one of water? But I will dwell no longer upon this +matter, whereon I have spoke sufficiently: but leaving _Democritus_, I +return to the Text of _Aristotle_, wherein he goes about to render the +true reason, how it comes to pass, that the thin Plates of Iron or +Lead do swim on the water; and, moreover, that Gold it self being +beaten into thin Leaves, not only swims in water, but flyeth too and +again in the Air. He supposeth that of Continualls[91], some are easily +divisible, others not: and that of the easily divisible, some are more +so, and some less: and these he affirms we should esteem the Causes. +He addes that that is easily divisible, which is well terminated, and +the more the more divisible, and that the Air is more so, than the +water, and the water than the Earth. And, lastly, supposeth that in +each kind, the lesse quantity is easlyer divided and broken than the +greater. + + [91] _De Cælo_ l. 4. c. 6. t. 44. + +Here I note, that the Conclusions of _Aristotle_ in generall are all +true, but methinks, that he applyeth them to particulars, in which +they have no place, as indeed they have in others, as for Example, Wax +is more easily divisible than Lead, and Lead than Silver, inasmuch as +Wax receives all the terms more easlier than Lead, and Lead than +Silver. Its true, moreover, that a little quantity of Silver is +easlier divided than a great Mass: and all these Propositions are +true, because true it is, that in Silver, Lead and Wax, there is +simply a Resistance against Division, and where there is the absolute, +there is also the respective. But if as well in water as in Air, there +be no Renitence against simple Division, how can we say, that the +water is easlier divided than the Air? We know not how to extricate +our selves from the Equivocation: whereupon I return to answer, that +Resistance of absolute Division is one thing, and Resistance of +Division made with such and such Velocity is another. But to produce +Rest, and to abate the Motion, the Resistance of absolute Division is +necessary; and the Resistance of speedy Division, causeth not Rest, +but slowness of Motion. But that as well in the Air, as in water, +there is no Resistance of simple Division, is manifest, for that there +is not found any Solid Body which divides not the Air, and also the +water: and that beaten Gold, or small dust, are not able to superate +the Resistance of the Air, is contrary to that which Experience shews +us, for we see Gold and Dust to go waving to and again in the Air, and +at last to descend downwards, and to do the same in the water, if it +be put therein, and separated from the Air. And, because, as I say, +neither the water, nor the Air do resist simple Division, it cannot be +said, that the water resists more than the Air. Nor let any object +unto me, the Example of most light Bodies, as a Feather, or a little +of the pith of Elder, or water-reed that divides the Air and not the +water, and from this infer, that the Air is easlier divisible than the +water; for I say unto them, that if they do well observe, they shall +see the same Body likewise divide the Continuity of the water[92], and +submerge in part, and in such a part, as that so much water in Mass +would weigh as much as the whole Solid. And if they shal yet persist +in their doubt, that such a Solid sinks not through inability to +divide the water, I will return them this reply, that if they put it +under water, and then let it go, they shall see it divide the water, +and presently ascend with no less celerity, than that with which it +divided the Air in descending: so that to say that this Solid ascends +in the Air, but that coming to the water, it ceaseth its Motion, and +therefore the water is more difficult to be divided, concludes +nothing: for I, on the contrary, will propose them a piece of Wood, or +of Wax, which riseth from the bottom of the water, and easily divides +its Resistance, which afterwards being arrived at the Air, stayeth +there, and hardly toucheth it; whence I may aswell say, that the water +is more easier divided than the Air. + + [92] _Archimed. De Insident. humi_ lib. 2. prop. 1. + +I will not on this occasion forbear to give warning of another fallacy +of these persons, who attribute the reason of sinking or swimming to +the greater or lesse Resistance of the Crassitude of the water against +Division, making use of the example of an Egg, which in sweet water +goeth to the bottom, but in salt water swims; and alledging for the +cause thereof, the faint Resistance of fresh water against Division, +and the strong Resistance of salt water. But if I mistake not, from +the same Experiment, we may aswell deduce the quite contrary; namely, +that the fresh water is more dense, and the salt more tenuous and +subtle, since an Egg from the bottom of salt water speedily ascends to +the top, and divides its Resistance, which it cannot do in the fresh, +in whose bottom it stays, being unable to rise upwards. Into such like +perplexities, do false Principles Lead men: but he that rightly +Philosophating, shall acknowledge the excesses of the Gravities of the +Moveables and of the Mediums, to be the Causes of those effects, will +say, that the Egg sinks to the bottom in fresh water, for that it is +more grave than it, and swimeth in the salt, for that its less grave +than it: and shall without any absurdity, very solidly establish his +Conclusions. + +Therefore the reason totally ceaseth, that _Aristotle_ subjoyns in the +Text saying[93]; The things, therefore, which have great breadth remain +above, because they comprehend much, and that which is greater, is not +easily divided. Such discoursing ceaseth, I say, because its not true, +that there is in water or in Air any Resistance of Division; besides +that the Plate of Lead when it stays, hath already divided and +penetrated the Crassitude of the water, and profounded it self ten or +twelve times more than its own thickness: besides that such Resistance +of Division, were it supposed to be in the water, could not rationally +be affirmed to be more in its superiour parts than in the middle, and +lower: but if there were any difference, the inferiour should be the +more dense, so that the Plate would be no less unable to penetrate the +lower, than the superiour parts of the water; nevertheless we see that +no sooner do we wet the superiour Superficies of the Board or thin +Piece of Wood, but it precipitatly, and without any retension, +descends to the bottom. + + [93] Text 45. + +I believe not after all this, that any (thinking perhaps thereby to +defend _Aristotle_) will say, that it being true, that the much water +resists more than the little, the said Board being put lower +descendeth, because there remaineth a less Mass of water to be divided +by it: because if after the having seen the same Board swim in four +Inches of water, and also after that in the same to sink, he shall try +the same Experiment upon a profundity of ten or twenty fathom water, +he shall see the very self same effect. And here I will take occasion +to remember, for the removall of an Error that is too common; That +that Ship or other whatsoever Body, that on the depth of an hundred or +a thousand fathom, swims with submerging only six fathom of its own +height, [_or in the Sea dialect, that draws six fathom water_] shall +swim in the same manner in water, that hath but six fathom and half an +Inch of depth[94]. Nor do I on the other side, think that it can be said, +that the superiour parts of the water are the more dense, although a +most grave Authour hath esteemed the superiour water in the Sea to be +so, grounding his opinion upon its being more salt, than that at the +bottom: but I doubt the Experiment, whether hitherto in taking the +water from the bottom, the Observatour did not light upon some spring +of fresh water there spouting up: but we plainly see on the contrary, +the fresh Waters of Rivers to dilate themselves for some miles beyond +their place of meeting with the salt water of the Sea, without +descending in it, or mixing with it, unless by the intervention of +some commotion or turbulency of the Windes. + + [94] A Ship that in 100 Fathome water draweth 6 Fathome, shall + float in 6 Fathome and 1/2 an Inch of depth. + +But returning to _Aristotle_, I say, that the breadth of Figure hath +nothing to do in this business more or less, because the said Plate of +Lead, or other Matter, cut into long Slices, swim neither more nor +less[95]; and the same shall the Slices do, being cut anew into little +pieces, because its not the breadth but the thickness that operates in +this business. I say farther, that in case it were really true, that +the Renitence to Division were the proper Cause of swimming[96], the +Figures more narrow and short, would much better swim than the more +spacious and broad, so that augmenting the breadth of the Figure, the +facility of supernatation will be deminished, and decreasing, that +this will encrease. + + [95] Thickness not breadth of Figure to be respected in Natation. + + [96] Were Renitence the cause of Natation, breadth of Figure would + hinder the swiming of Bodies. + +And for declaration of what I say, consider that when a thin Plate of +Lead descends, dividing the water, the Division and discontinuation is +made between the parts of the water, invironing the perimeter or +Circumference of the said Plate, and according to the bigness greater +or lesser of that circuit, it hath to divide a greater or lesser +quantity of water, so that if the circuit, suppose of a Board, be ten +Feet in sinking it flatways, it is to make the seperation and +division, and to so speak, an incission upon ten Feet of water; and +likewise a lesser Board that is four Feet in Perimeter, must make an +incession of four Feet. This granted, he that hath any knowledge in +Geometry, will comprehend, not only that a Board sawed in many long +thin pieces, will much better float than when it was entire, but that +all Figures, the more short and narrow they be, shall so much the +better swim. Let the Board A B C D be, for Example, eight Palmes long, +and five broad, its circuit shall be twenty six Palmes; and so many +must the incession be, which it shall make in the water to descend +therein: but if we do saw ir, as suppose into eight little pieces, +according to the Lines E F, G H, {&}c. making seven Segments, we must +adde to the twenty six Palmes of the circuit of the whole Board, +seventy others; whereupon the eight little pieces so cut and +seperated, have to cut ninty six Palmes of water. And, if moreover, we +cut each of the said pieces into five parts, reducing them into +Squares, to the circuit of ninty six Palmes, with four cuts of eight +Palmes apiece; we shall adde also sixty four Palmes, whereupon the +said Squares to descend in the water, must divide one hundred and +sixty Palmes of water, but the Resistance is much greater than that of +twenty six; therefore to the lesser Superficies, we shall reduce them, +so much the more easily will they float: and the same will happen in +all other Figures, whose Superficies are simular amongst themselves, +but different in bigness: because the said Superficies, being either +deminished or encreased, always diminish or encrease their Perimeters +in subduple proportion; to wit, the Resistance that they find in +penetrating the water; therefore the little pieces gradually swim, +with more and more facility as their breadth is lessened. + +[Illustration] + + _This is manifest; for keeping still the same height of the Solid, + with the same proportion as the Base encreaseth or deminisheth, + doth the said Solid also encrease or diminish; whereupon the Solid + more diminishing than the Circuit, the Cause of Submersion more + diminisheth than the Cause of Natation: And on the contrary, the + Solid more encreasing than the Circuit, the Cause of Submersion + encreaseth more, that of Natation less._ + +And this may all be deduced out of the Doctrine of _Aristotle_ against +his own Doctrine. + +Lastly, to that which we read in the latter part of the Text[97], that is +to say, that we must compare the Gravity of the Moveable with the +Resistance of the Medium against Division, because if the force of the +Gravity exceed the Resistance of the _Medium_, the Moveable will +descend, if not it will float. I need not make any other answer, but +that which hath been already delivered; namely, that its not the +Resistance of absolute Division, (which neither is in Water nor Air) +but the Gravity of the _Medium_ that must be compared with the Gravity +of the Moveables; and if that of the _Medium_ be greater, the Moveable +shall not descend, nor so much as make a totall Submersion, but a +partiall only; because in the place which it would occupy in the +water, there must not remain a Body that weighs less than a like +quantity of water: but if the Moveable be more grave, it shall descend +to the bottom, and possess a place where it is more conformable for it +to remain, than another Body that is less grave. And this is the only +true proper and absolute Cause of Natation and Submersion, so that +nothing else hath part therein: and the Board of the Adversaries +swimmeth, when it is conjoyned with as much Air, as, together with it, +doth form a Body less grave than so much water as would fill the place +that the said Compound occupyes in the water; but when they shall +demit the simple Ebony into the water, according to the Tenour of our +Question, it shall alwayes go to the bottom, though it were as thin as +a Paper. + + [97] Lib. 4. c. 6. Text 45. + +[Decoration] + +FINIS. + +[Decoration] + + * * * * * + + [Detailed Transcriber's Notes + + The text has been made to match the original text as much as + possible including variation in spelling, punctuation, italics etc. + The following, details apparent printer's errors as well as changes + or additions to aid readability of text. + + Page 1, missing full stop after abbreviation gr. '0 gr 54 min.'. + + Page 3, sidenote, missing space between words 'the Authority ofan + Author.'. + + Page 3, printer's error, augmentarion for augmentation 'and + augmentarion of Masse'. + + Page 4, missing letter t 'tha{t} that proceeded not'. + + Page 4, printer's error or inconsistent punctuation, 'my paynes and + time. and although'. + + Page 6, inconsistent punctuation, full stop after axiome where as + there are none after those following 'AXIOME. I.'. + + Page 9, missing full stop added to end of paragraph 'or else an + upright Prisme.'. + + Page 11, printer's error, missing letter C in illustration, 'the + Prisme A C D B to be placed'. + + Page 15, printer's error or archaic lettering, final y looking like + a 7 in original text'and of the Specifick Gravit{y}'. + + Page 16, printer's error, letter N for T in text to refer to + illustration, 'if the Vessell E N S F'. + + Page 16, printer's error, duplicate word in text 'equalizeth the + Force and and Moment,'. + + Page 17, printer's error, rhe for the 'as in rhe Stilliard,'. + + Page 17, missing space between words 'asoften as that'. + + Page 18, sidenote, printer's error, specifiaclly for specifically + 'A Solid specifiaclly graver'. + + Page 20, potential printer's error, properly for property, 'but + this properly they have'. + + Page 20, printer's error, n for u 'loseth all a{u}thenticalness'. + + Page 22, printer's error or variation in spelling, Benonamico for + Buonamico 'it seemes that Benonamico'. + + Page 23, printer's error, missing i 'accordng to its excess'. + + Page 24, missing line at the end of page in original text 'its + Region it loseth all'. + + Page 26, missing letter n 'u{n}able by its small weight'. + + Page 29, missing letter e 'that I have gon{e} about'. + + Page 32, unclear symbol in original text 'other Figure, {&}c.'. + + Page 37, potential printer's error, comma in unusual position + 'whatever Figure, goeth always'. + + Page 38, missing space between words 'Superficies might bedry:'. + + Page 39, missing letter t, unied for united 'which holds them unied'. + + Page 41, printer's error, Motitions for Motions 'all Motitions are + made'. + + Page 42, sidenote, possible missing letter e, 'Se{e} what satisfaction'. + + Page 43, printer's error, Subdidivisions for Subdivisions, 'other + Subdidivisions,'. + + Page 49, missing letter i, dminishing for diminishing 'or dminishing + it by dividing'. + + Page 50, sidenote, printer's error, missing letter l, hep for help + 'float by hep of'. + + Page 53, printer's error, missing letter n, beig for being 'beig + double in Gravity'. + + Page 54, printer's error, missing letter l, 'sha{l}l also descend.'. + + Page 55, printer's error, missing letter r, 'to fo{r}m Solid Bodies'. + + Page 56, printer's error, missing letter A, 'Cone S {A} T'. + + Page 57, printer's error, missing letter t, 'of which i{t} may + descend'. + + Page 58, sidenote, printer's error, inverted n, 'Natatio{n} easiest + effected'. + + Page 59, missing letter u, 'witho{u}t all Question,'. + + Page 59, printer's error, inverted n, 'with an other Experime{n}t'. + + Page 59, potential printer's error, sidenote ends with comma, 'Or + rather Contiguity,'. + + Page 61, missing letter a, 'that in this c{a}se the water,'. + + Page 74, printer's error, ir for it, 'but if we do saw ir,'. + + Page 75, unclear symbol in original text '{&}c. making seven + Segments'. + ] + + + + + +End of Project Gutenberg's Discourse on Floating Bodies, by Galileo Galilei + +*** END OF THIS PROJECT GUTENBERG EBOOK DISCOURSE ON FLOATING BODIES *** + +***** This file should be named 37729-8.txt or 37729-8.zip ***** +This and all associated files of various formats will be found in: + https://www.gutenberg.org/3/7/7/2/37729/ + +Produced by Tim Madden and the Online Distributed +Proofreading Team at https://www.pgdp.net (This file was +produced from images generously made available by The +Internet Archive) + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. 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You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: Discourse on Floating Bodies + +Author: Galileo Galilei + +Translator: Thomas Salusbury + +Release Date: October 12, 2011 [EBook #37729] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK DISCOURSE ON FLOATING BODIES *** + + + + +Produced by Tim Madden and the Online Distributed +Proofreading Team at https://www.pgdp.net (This file was +produced from images generously made available by The +Internet Archive) + + + + + + +</pre> + + + +<div class="bbox"> + <p><b>Transcriber's Notes:</b></p> + + <p>All apparent printer's errors retained. Variation in punctuation are + as in the original, but missing full stops at end of paragraphs have + been supplied. There are inconsistencies in the use of italics, + spacing of words and use of full stop after 'AXIOME', abbreviations + etc. All are retained to match text. There is a great variation in + spelling including multiple spellings of the same word, all spelling + has been retained to match text. There are several instances of + obviously missing letters or inverted n & u. These have been changed + or obvious letters replaced, with the changes surrounded by {}.</p> + + <p>All instances are detailed at the end of the text. It should also be + noted that in the original text there is a missing line at the end of + page 24 in original text.</p> + + <p>There are a number of instances in the original text where 'that' is + immediately followed by a second 'that' in the sentence. These could + be potential printer's errors or, since several of them make sense, + part of the author's style. They have been left in the text as they + appear in the original text.</p> + + <p>The images have been retouched to clean up the diagrams and to improve + readability of lettering where possible.</p> + +</div> + +<hr style="width: 65%;" /> + + + + +<p class="center bt_m">A</p> +<p class="center bt_vvl">DISCOURSE</p> +<p class="center bt_vsp"><i>PRESENTED</i></p> +<p class="center bt_m bt_vsp">TO THE MOST SERENE</p> +<p class="center bt_l">Don Cosimo II.</p> +<p class="center bt_vl">GREAT DUKE</p> +<p class="center bt_m bt_sp"><i>OF</i></p> +<p class="center bt_vvl bt_sp">TUSCANY,</p> + +<p class="center bt_sp">CONCERNING</p> + +<p class="center bt_m">The <i class="bt_sp">NATATION</i> of <span class="bt_sp">BODIES</span> Vpon,</p> +<p class="center bt_m">And<i class="bt_sp"> SUBMERSION </i>In,</p> +<p class="center bt_vsp">THE</p> +<p class="center bt_vvl bt_sp">WATER.</p> + +<p class="center">By <span class="smcap bt_sp">Galileus Galilei</span>: Philosopher and</p> +<p class="center bt_s">Mathematician unto His most Serene Highnesse.</p> + +<hr style="width: 65%;" /> + +<p class="center">Englished from the Second Edition of the <span class="smcap bt_sp">Italian</span>,</p> +<p class="center bt_s">compared with the Manuscript Copies, and reduced</p> +<p class="center bt_s">into <span class="bt_sp">PROPOSITIONS</span>:</p> + +<p class="center">By<i class="bt_sp"> THOMAS SALUSBURY</i>, Esq;</p> + +<hr style="width: 65%;" /> + +<p class="center"><i class="bt_sp bt_ms">LONDON</i>:</p> + +<p class="center bt_ms">Printed by <span class="smcap bt_sp">William Leybourn</span>:</p> + +<p class="center bt_ms bt_sp"><i>M DC LXIII.</i></p> +<p> </p> +<p> </p> +<p> </p> +<p> </p> + +<p><span class="pagenum"><a name="Page_1" id="Page_1">[Pg 1]</a></span></p> +<div class="figcenter" style="width: 605px;"> +<img src="images/i003a.png" width="605" height="43" alt="" title="" /> +</div> + +<p class="center bt_l bt_vsp"> A DISCOVRSE</p> + +<p class="center">Presented to the Most Serene <span class="smcap bt_sp">Don Cosimo</span> II.</p> + +<p class="center"><span class="smcap">Great Duke</span> of<i class="bt_sp"> TUSCANY</i>:</p> + +<p class="center bt_sp bt_ms">CONCERNING</p> + +<p class="center"><i>The Natation of<span class="bt_sp"> BODIES</span> Upon, or Submersion</i></p> +<p class="center"><i>In, the<span class="bt_sp"> WATER</span>.</i></p> + + +<div class="figleft_dc" style="width: 105px;"> +<img src="images/i003b.png" width="105" height="119" alt="C" title="" /> +</div> + +<p>Onsidering (Most Serene Prince) that the publishing this present +Treatise, of so different an Argument from that which many expect, and +which according to the intentions I proposed in my * Astronomicall <span class="sidenote">His Nuncio Siderio.</span> +<i>Adviso</i>, I should before this time have put forth, might peradventure +make some thinke, either that I had wholly relinquished my farther +imployment about the new Celestiall Observations, or that, at least, I +handled them very remissely; I have judged fit to render an account, +aswell of my deferring that, as of my writing, and publishing this +treatise.</p> + +<p>As to the first, the last discoveries of <i>Saturn</i> to be +tricorporeall, and of the mutations of Figure in <i>Venus</i>, like to +those that are seen in the Moon, together with the Consequents +depending thereupon, have not so much occasioned the demur, as the +investigation of the times of the Conversions of each of the Four +Medicean Planets about <i>Jupiter</i>, which I lighted upon in <i>April</i> the +year past, 1611, at my being in <i>Rome</i>; where, in the end, I +assertained my selfe, that the first and neerest to <i>Jupiter</i>, moved +about 8 <i>gr.</i> & 29 <i>m.</i> of its Sphere in an houre, makeing its whole +revolution in one naturall day, and 18 hours, and almost an halfe. The +second moves in its Orbe 14 <i>gr.</i> 13 <i>min.</i> or very neer, in an hour, +and its compleat conversion is consummate in 3 dayes, 13 hours, and +one third, or thereabouts. The third passeth in an hour, 2 <i>gr.</i> 6 +<i>min.</i> little more or less of its Circle, and measures it all in 7 +dayes, 4 hours, or very neer. The fourth, and more remote than the +rest, goes in one houre, <a name="tnd_1" id="tnd_1"></a><a href="#tn_1" class="tnlink" title="missing full stop after abbreviation gr.">0 <i>gr</i> 54 <i>min.</i></a> and almost an halfe of its +Sphere, and finisheth it all in 16 dayes, and very neer 18 hours. But +because the excessive velocity of their returns or restitutions, +requires a most scrupulous precisenesse to calculate their places, in +<span class="pagenum"><a name="Page_2" id="Page_2">[Pg 2]</a></span> +times past and future, especially if the time be for many Moneths or +Years; I am therefore forced, with other Observations, and more exact +than the former, and in times more remote from one another, to correct +the Tables of such Motions, and limit them even to the shortest +moment: for such exactnesse my first Observations suffice not; not +only in regard of the short intervals of Time, but because I had not +as then found out a way to measure the distances between the said +Planets by any Instrument: I Observed such Intervals with simple +relation to the Diameter of the Body of <i>Jupiter</i>; taken, as we have +said, by the eye, the which, though they admit not errors of above a +Minute, yet they suffice not for the determination of the exact +greatness of the Spheres of those Stars. But now that I have hit upon +a way of taking such measures without failing, scarce in a very few +Seconds, I will continue the observation to the very occultation of +<span class="bt_ssp"><i>JUPITER</i></span>, which shall serve to bring us to the perfect knowledge of +the Motions, and Magnitudes of the Orbes of the said Planets, together <span class="sidenote">The Authors Observations of the Solar Spots</span> +also with some other consequences thence arising. I adde to these +things the observation of some obscure Spots, which are discovered in +the Solar Body, which changing, position in that, propounds to our +consideration a great argument either that the Sun revolves in it +selfe, or that perhaps other Starrs, in like manner as <i>Venus</i> and +<i>Mercury</i>, revolve about it, invisible in other times, by reason of +their small digressions, lesse than that of <i>Mercury</i>, and only +visible when they interpose between the Sun and our eye, or else hint +the truth of both this and that; the certainty of which things ought +not to be contemned, nor omitted.</p> + +<p><i>Continuall observation hath at last assured me that these Spots +are matters contiguous to the Body of the Sun, there continually +produced in great number, and afterwards dissolved, some in a +shorter, some in a longer time, and to be by the Conversion or +Revolution of the Sun in it selfe, which in a Lunar Moneth, or +thereabouts, finisheth its Period, caried about in a Circle, an +accident great of it selfe, and greater for its Consequences.</i></p> + +<div class="sidenote">The occasion inducing the Author to write this +Treatise.</div> + +<p>As to the other particular in the next place * Many causes have +moved me to write the present Tract, the subject whereof, is the +Dispute which I held some dayes since, with some learned men of this +City, about which, as your Highnesse knows, have followed many +Discourses: The principall of which Causes hath been the Intimation of +your Highnesse, having commended to me Writing, as a singular means to +make true known from false, reall from apparent Reasons, farr better +than by Disputing vocally, where the one or the other, or very often +<span class="pagenum"><a name="Page_3" id="Page_3">[Pg 3]</a></span> +both the Disputants, through too greate heate, or exalting of the +voyce, either are not understood, or else being transported by +ostentation of not yeilding to one another, farr from the first +Proposition, with the novelty, of the various Proposals, confound both +themselves and their Auditors.</p> + +<p>Moreover, it seemed to me convenient to informe your Highnesse of all +the sequell, concerning the Controversie of which I treat, as it hath +been advertised often already by others: and because the Doctrine +which I follow, in the discussion of the point in hand, is different +from that of <i>Aristotle</i>; and interferes with his Principles, I have +considered that against the Authority of that most famous Man, which +amongst many makes all suspected that comes not from the Schooles of +the Peripateticks, its farr better to give ones Reasons by the Pen +than by word of mouth, and therfore I resolved to write the present +discourse: in which yet I hope to demonstrate that it was not out of +capritiousnesse, or for that I had not read or understood <i>Aristotle</i>, +that I sometimes swerve from his opinion, but because severall Reasons +perswade me to it, and the same <i>Aristotle</i> hath tought me to fix my +judgment on that which is grounded upon Reason, and not on the bare +<span class="sidenote"><i>Aristotle</i> prefers Reason to the <a name="tnd_3a" id="tnd_3a"></a><a href="#tn_3a" class="tnlink" title="missing space between words">Authority ofan +Author.</a></span> +Authority of the Master; and it is most certaine according to the +sentence of <i>Alcinoos</i>, that philosophating should be free. Nor is the +resolution of our Question in my judgment without some benefit to the +<span class="sidenote">The benefit of this Argument.</span> +Universall, forasmuch as treating whether the figure of Solids +operates, or not, in their going, or not going to the bottome in +Water, in occurrences of building Bridges or other Fabricks on the +Water, which happen commonly in affairs of grand import, it may be of +great availe to know the truth.</p> + +<p>I say therfore, that being the last Summer in company with certain +Learned men, it was said in the argumentation; That Condensation was +<span class="sidenote">Condensation the Propriety of Cold, according to the +Peripateticks.</span> +the propriety of Cold, and there was alledged for instance, the +example of Ice: now I at that time said, that, in my judgment, the Ice +<span class="sidenote">Ice rather water rarified, than condensed, and why:</span> +should be rather Water rarified than condensed, and my reason was, +because Condensation begets diminution of Mass, and augmentation of +gravity, and Rarifaction causeth greater Lightness, <a name="tnd_3b" id="tnd_3b"></a><a href="#tn_3b" class="tnlink" title="printer's error, augmentarion for augmentation">and augmentarion +of Masse:</a> and Water in freezing, encreaseth in Masse, and the Ice made +thereby is lighter than the Water on which it swimmeth.</p> + +<p><i>What I say, is manifest, because, the medium subtracting from the +whole Gravity of Sollids the weight of such another Masse of the +<span class="sidenote">In lib: 1. of Natation of Bodies Prop. 7.</span> +said Medium; as</i> Archimedes <i>proves in his</i> * First Booke De +Insidentibus Humido; <i>when ever the Masse of the said Solid +encreaseth by Distraction, the more shall the</i> Medium <i>detract from +its entire Gravity; and lesse, when by Compression it shall be +condensed and reduced to a lesse Masse.</i></p> +<p><span class="pagenum"><a name="Page_4" id="Page_4">[Pg 4]</a></span></p> +<div class="sidenote">Figure operates not in the Natation of Sollids.</div> + +<p>It was answered me, <a name="tnd_4a" id="tnd_4a"></a><a href="#tn_4a" class="tnlink" title="missing letter t">tha{t} that proceeded not</a> from the greater Levity, +but from the Figure, large and flat, which not being able to penetrate +the Resistance of the Water, is the cause that it submergeth not. I +replied, that any piece of Ice, of whatsoever Figure, swims upon the +Water, a manifest signe, that its being never so flat and broad, hath +not any part in its floating: and added, that it was a manifest proofe +hereof to see a piece of Ice of very broad Figure being thrust to the +botome of the Water, suddenly return to flote atoppe, which had it +been more grave, and had its swimming proceeded from its Forme, unable +to penetrate the Resistance of the <i>Medium</i>, that would be altogether +impossible; I concluded therefore, that the Figure was in sort a Cause +of the Natation or Submersion of Bodies, but the greater or lesse +Gravity in respect of the Water: and therefore all Bodyes heavier than +it of what Figure soever they be, indifferently go to the bottome, and +the lighter, though of any figure, float indifferently on the top: and +I suppose that those which hold otherwise, were induced to that +beliefe, by seeing how that diversity of Formes or Figures, greatly +altereth the Velosity, and Tardity of Motion; so that Bodies of Figure +broad and thin, descend far more leasurely into the Water, than those +of a more compacted Figure, though both made of the same Matter: by +which some might be induced to believe that the Dilatation of the +Figure might reduce it to such amplenesse that it should not only +retard but wholly impede and take away the Motion, which I hold to be +false. Upon this Conclusion, in many dayes discourse, was spoken much, +and many things, and divers Experiments produced, of which your +Highnesse heard, and saw some, and in this discourse shall have all +that which hath been produced against my Assertion, and what hath been +suggested to my thoughts on this matter, and for confirmation of my +Conclusion: which if it shall suffice to remove that (as I esteem +hitherto false) Opinion, I shall thinke I have not unprofitably spent +<a name="tnd_4b" id="tnd_4b"></a><a href="#tn_4b" class="tnlink" title="printer's error or inconsistent punctuation">my paynes and time. and although</a> that come not to passe, yet ought I +to promise another benefit to my selfe, namely, of attaining the +knowledge of the truth, by hearing my Fallacyes confuted, and true +demonstrations produced by those of the contrary opinion.</p> + +<p>And to proceed with the greatest plainness and perspicuity that I can +possible, it is, I conceive, necessary, first of all to declare what +is the true, intrinsecall, and totall Cause, of the ascending of some +Sollid Bodyes in the Water, and therein floating; or on the contrary, +of their sinking and so much the rather in asmuch as I cannot satisfie +myselfe in that which <i>Aristotle</i> hath left written on this Subject.</p> + +<div class="sidenote">The cause of the Natation & submersion of Solids in +the Water.</div> + +<p><span class="pagenum"><a name="Page_5" id="Page_5">[Pg 5]</a></span></p> +<p>I say then the Cause why some Sollid Bodyes descend to the Bottom of +Water, is the excesse of their Gravity, above the Gravity of the +Water; and on the contrary, the excess of the Waters Gravity above the +Gravity of those, is the Cause that others do not descend, rather that +they rise from the Bottom, and ascend to the Surface. This was +subtilly demonstrated by <i>Archimedes</i> in his Book Of the <span class="smcap bt_ssp">Natation</span> of +<span class="smcap bt_ssp">Bodies</span>: Conferred afterwards by a very grave Author, but, if I erre +not invisibly, as below for defence of him, I shall endeavour to +prove.</p> + +<p>I, with a different Method, and by other meanes, will endeavour to +demonstrate the same, reducing the Causes of such Effects to more +intrinsecall and immediate Principles, in which also are discovered +the Causes of some admirable and almost incredible Accidents, as that +would be, that a very little quantity of Water, should be able, with +its small weight, to raise and sustain a Solid Body, an hundred or a +thousand times heavier than it.</p> + +<p>And because demonstrative Order so requires, I shall define certain +Termes, and afterwards explain some Propositions, of which, as of +things true and obvious, I may make use of to my present purpose.</p> + + + + +<h2><a name="DEFINITION_I" id="DEFINITION_I"></a>DEFINITION I.</h2> + +<p class="def_head"><i>I then call equally Grave</i> in specie, <i>those Matters of which equall +Masses weigh equally.</i></p> + + +<p>As if for example, two Balls, one of Wax, and the other of some Wood +of equall Masse, were also equall in Weight, we say, that such Wood, +and the Wax are <i>in specie</i> equally grave.</p> + + + + +<h2><a name="DEFINITION_II" id="DEFINITION_II"></a>DEFINITION II.</h2> + +<p class="def_head"><i>But equally grave in Absolute Gravity, we call two Sollids, +weighing equally, though of Mass they be unequall.</i></p> + + +<p>As for example, a Mass of Lead, and another of Wood, that weigh each +ten pounds, I call equall in Absolute Gravity, though the Mass of the +Wood be much greater then that of the Lead.</p> + +<p><i>And, consequently, less Grave</i> in specie.</p> + + + + +<h2><a name="DEFINITION_III" id="DEFINITION_III"></a>DEFINITION III.</h2> + +<p class="def_head"><i>I call a Matter more Grave</i> in specie <i>than another, of which a +Mass, equall to a Mass of the other, shall weigh more.</i></p> + + +<p><span class="pagenum"><a name="Page_6" id="Page_6">[Pg 6]</a></span></p> +<p>And so I say, that Lead is more grave <i>in specie</i> than Tinn, because +if you take of them two equall Masses, that of the Lead weigheth more.</p> + + + + +<h2><a name="DEFINITION_IV" id="DEFINITION_IV"></a>DEFINITION IV.</h2> + +<p class="def_head"><i>But I call that Body more grave absolutely than this, if that +weigh more than this, without any respect had to the Masses.</i></p> + + +<p>And thus a great piece of Wood is said to weigh more than a little +lump of Lead, though the Lead be <i>in specie</i> more heavy than the Wood. +And the same is to be understood of the less grave <i>in specie</i>, and +the less grave absolutely.</p> + +<p>These Termes defined, I take from the Mechanicks two Principles: the +first is, that</p> + + + + +<h2><a name="AXIOME_I" id="AXIOME_I"></a><a name="tnd_6" id="tnd_6"></a><a href="#tn_6" class="tnlink" title="inconsistent punctuation, full stop after axiome">AXIOME. I.</a></h2> + +<p class="def_head"><i>Weights absolutely equall, moved with equall Velocity, are of +equall Force and Moment in their operations.</i></p> + + + +<h2><a name="DEFINITION_V" id="DEFINITION_V"></a><i>DEFINITION V.</i></h2> + +<p class="def_head">Moment, amongst Mechanicians, signifieth that Vertue, that Force, +or that Efficacy, with which the Mover moves, and the Moveable +resists.</p> + + +<p><i>Which Vertue dependes not only on the simple Gravity, but on the +Velocity of the Motion, and on the diverse Inclinations of the +Spaces along which the Motion is made: For a descending Weight +makes a greater Impetus in a Space much declining, than in one less +declining; and in summe, what ever is the occasion of such Vertue, +it ever retaines the name of Moment; nor in my Judgement, is this +sence new in our Idiome, for, if I mistake not, I think we often +say; This is a weighty businesse, but the other is of small moment: +and we consider lighter matters and let pass those of Moment; a +Metaphor, I suppose, taken from the Mechanicks.</i></p> + +<p>As for example, two weights equall in absolute Gravity, being put +into a Ballance of equall Arms, they stand in <i>Equilibrium</i>, neither +one going down, nor the other up: because the equality of the +Distances of both, from the Centre on which the Ballance is supported, +and about which it moves, causeth that those weights, the said +Ballance moving, shall in the same Time move equall Spaces, that is, +shall move with equall Velocity, so that there is no reason for which +<span class="pagenum"><a name="Page_7" id="Page_7">[Pg 7]</a></span> +this Weight should descend more than that, or that more than this; and +therefore they make an <i>Equilibrium</i>, and their Moments continue of +semblable and equall Vertue.</p> + +<p>The second Principle is; That</p> + + + + +<h2><a name="AXIOME_II" id="AXIOME_II"></a>AXIOME II.</h2> + +<p class="def_head"><i>The Moment and Force of the Gravity, is encreased by the Velocity +of the Motion.</i></p> + + +<p>So that Weights absolutely equall, but conjoyned with Velocity +unequall, are of Force, Moment and Vertue unequall: and the more +potent, the more swift, according to the proportion of the Velocity of +the one, to the Velocity of the other. Of this we have a very +pertinent example in the Balance or Stiliard of unequall Arms, at +which Weights absolutely equall being suspended, they do not weigh +down, and gravitate equally, but that which is at a greater distance +from the Centre, about which the Beam moves, descends, raising the +other, and the Motion of this which ascends is slow, and the other +swift: and such is the Force and Vertue, which from the Velocity of +the Mover, is conferred on the Moveable, which receives it, that it +can exquisitely compensate, as much more Weight added to the other +slower Moveable: so that if of the Arms of the Balance, one were ten +times as long as the other, whereupon in the Beames moving about the +Centre, the end of that would go ten times as far as the end of this, +a Weight suspended at the greater distance, may sustain and poyse +another ten times more grave absolutely than it: and that because the +Stiliard moving, the lesser Weight shall move ten times faster than +the bigger. It ought alwayes therefore to be understood, that Motions +are according to the same Inclinations, namely, that if one of the +Moveables move perpendicularly to the Horizon, then the other makes +its Motion by the like Perpendicular; and if the Motion of one were to +be made Horizontally; that then the other is made along the same +Horizontall plain: and in summe, alwayes both in like Inclinations. +This proportion between the Gravity and Velocity is found in all +Mechanicall Instruments: and is considered by <i>Aristotle</i>, as a +Principle in his <i>Mechanicall Questions</i>; whereupon we also may take +it for a true Assumption, That</p> + + + + +<h2><a name="AXIOME_III" id="AXIOME_III"></a>AXIOME III.</h2> + +<p class="def_head"><i>Weights absolutely unequall, do alternately counterpoyse and +become of equall Moments, as oft as their Gravities, with +contrary proportion, answer to the Velocity of their Motions.</i></p> + + +<p><span class="pagenum"><a name="Page_8" id="Page_8">[Pg 8]</a></span></p> +<p>That is to say, that by how much the one is less grave than the other, +by so much is it in a constitution of moving more swiftly than that.</p> + +<p>Having prefatically explicated these things, we may begin to enquire, +what Bodyes those are which totally submerge in Water, and go to the +Bottom, and which those that by constraint float on the top, so that +being thrust by violence under Water, they return to swim, with one +part of their Mass visible above the Surface of the Water: and this we +will do by considering the respective operation of the said Solids, +and of Water: Which operation followes the Submersion and sinking; and +<span class="sidenote">How the submersion of Solids in the Water, is +effected.</span> +this it is, That in the Submersion that the Solid maketh, being +depressed downwards by its proper Gravity, it comes to drive away the +water from the place where it successively subenters, and the water +repulsed riseth and ascends above its first levell, to which Ascent on +the other side it, as being a grave Body of its own nature, resists: +And because the descending Solid more and more immerging, greater and +greater quantity of Water ascends, till the whole Sollid be submerged; +its necessary to compare the Moments of the Resistance of the water to +Ascension, with the Moments of the pressive Gravity of the Solid: And +if the Moments of the Resistance of the water, shall equalize the +<span class="sidenote">What Solids shall float on the Water.</span> +Moments of the Solid, before its totall Immersion; in this case +doubtless there shall be made an <i>Equilibrium</i>, nor shall the Body +sink any farther. But if the Moment of the Solid, shall alwayes exceed +the Moments wherewith the repulsed water successively makes +<span class="sidenote">What Solids shall sinke to the botome.</span> +Resistance, that Solid shall not only wholly submerge under water, but +shall descend to the Bottom. But if, lastly, in the instant of totall +Submersion, the equality shall be made between the Moments of the +<span class="sidenote">What Solids shall rest in all places of the Water.</span> +prement Solid, and the resisting Water; then shall rest, ensue, and +the said Solid shall be able to rest indifferently, in whatsoever part +of the water. By this time is manifest the necessity of comparing the +<span class="sidenote">The Gravitie of the Water and Solid must be compared in +all Problems, of Natation of Bodies.</span> +Gravity of the water, and of the Solid; and this comparison might at +first sight seem sufficient to conclude and determine which are the +Solids that float a-top, and which those that sink to the Bottom in +the water, asserting that those shall float which are lesse grave <i>in +specie</i> than the water, and those submerge, which are <i>in specie</i> more +grave. For it seems in appearance, that the Sollid in sinking +continually, raiseth so much Water in Mass, as answers to the parts of +its own Bulk submerged: whereupon it is impossible, that a Solid less +grave <i>in specie</i>, than water, should wholly sink, as being unable to +raise a weight greater than its own, and such would a Mass of water +equall to its own Mass be. And likewise it seems necessary, that the +graver Solids do go to the Bottom, as being of a Force more than +sufficient for the raising a Masse of water, equall to its own, though +inferiour in weight. Nevertheless the business succeeds otherwise: and +<span class="pagenum"><a name="Page_9" id="Page_9">[Pg 9]</a></span> +though the Conclusions are true, yet are the Causes thus assigned +deficient, nor is it true, that the Solid in submerging, raiseth and +repulseth Masses of Water, equall to the parts of it self submerged; +but the Water repulsed, is alwayes less than the parts of the Solid +<span class="sidenote">The water repelled is ever less than the parts of the +Sollid submerged.</span> +submerged: and so much the more by how much the Vessell in which the +Water is contained is narrower: in such manner that it hinders not, +but that a Solid may submerge all under Water, without raising so much +Water in Mass, as would equall the tenth or twentieth part of its own +Bulk: like as on the contrary, a very small quantity of Water, may +<span class="sidenote"><i>A</i> small quantity of water, may float a very great +Solid Mass.</span> +raise a very great Solid Mass, though such Solid should weigh +absolutely a hundred times as much, or more, than the said Water, if +so be that the Matter of that same Solid be <i>in specie</i> less grave +than the Water. And thus a great Beam, as suppose of a 1000 weight, +may be raised and born afloat by Water, which weighs not 50: and this +happens when the Moment of the Water is compensated by the Velocity of +its Motion.</p> + +<p>But because such things, propounded thus in abstract, are somewhat +difficult to be comprehended, it would be good to demonstrate them by +particular examples; and for facility of demonstration, we will +suppose the Vessels in which we are to put the Water, and place the +Solids, to be inviron'd and included with sides erected perpendicular +to the Plane of the Horizon, and the Solid that is to be put into such +vessell to be either a streight Cylinder, <a name="tnd_9" id="tnd_9"></a><a href="#tn_9" class="tnlink" title="missing full stop added to end of paragraph">or else an upright Prisme.</a></p> + +<p><i>The which proposed and declared, I proceed to demonstrate the truth +of what hath been hinted, forming the ensuing Theoreme.</i></p> + + + + +<h2><a name="THEOREME_I" id="THEOREME_I"></a><i>THEOREME I.</i></h2> + +<div class="sidenote">The Proportion of the water raised to the Solid +submerged.</div> + +<p class="def_head">The Mass of the Water which ascends in the submerging of a Solid, +Prisme or Cylinder, or that abaseth in taking it out, is less +than the Mass of the said Solid, so depressed or advanced: and +hath to it the same proportion, that the Surface of the Water +circumfusing the Solid, hath to the same circumfused Surface, +together with the Base of the Solid.</p> + +<p class="cap">L<i>et the Vessell be A B C D, and in it the Water raised up to the +Levell E F G, before the Solid Prisme H I K be therein immerged; but +after that it is depressed under Water, let the Water be raised as +high as the Levell L M, the Solid H I K shall then be all under Water, +and the Mass of the elevated Water shall be L G, which is less than +<span class="pagenum"><a name="Page_10" id="Page_10">[Pg 10]</a></span> +<span class="figleft" style="width: 220px;"> + <img src="images/i012.png" width="220" height="237" alt="" title="" /> +</span> +the Masse of the Solid depressed, namely of H I K, being equall to the +only part E I K, which is contained under the first Levell E F G. +Which is manifest, because if the Solid H I K be taken out, the Water +I G shall return into the place occupied by the Mass E I K, where it +was continuate before the submersion of the Prisme. And the Mass L G +being equall to the Mass E K: adde thereto the Mass E N, and it shall +be the whole Mass E M, composed of the parts of the Prisme E N, and of +the Water N F, equall to the whole Solid H I K: And, therefore, the +Mass L G shall have the same proportion to E M, as to the Mass H I K: +But the Mass L G hath the same proportion to the Mass E M, as the +Surface L M hath to the Surface M H: Therefore it is manifest, that +the Mass of Water repulsed L G, is in proportion to the Mass of the +Solid submerged H I K; as the Surface L M, namely, that of the Water +ambient about the Sollid, to the whole Surface H M, compounded of the +said ambient water, and the Base of the Prisme H N. But if we suppose +the first Levell of the Water the according to the Surface H M, and +the Prisme allready submerged H I K; and after to be taken out and +raised to E A O, and the Water to be faln from the first Levell H L M +as low as E F G; It is manifest, that the Prisme E A O being the same +with H I K, its superiour part H O, shall be equall to the inferiour E +I K: and remove the common part E N, and, consequently, the Mass of +the Water L G is equall to the Mass H O; and, therefore, less than the +Solid, which is without the Water, namely, the whole Prisme E A O, to +which likewise, the said Mass of Water abated L G, hath the same +proportion, that the Surface of the Waters circumfused L M hath to the +same circumfused Surface, together with the Base of the Prisme A O: +which hath the same demonstration with the former case above.</i></p> + +<p><i>And from hence is inferred, that the Mass of the Water, that riseth +in the immersion of the Solid, or that ebbeth in elevating it, is not +equall to all the Mass of the Solid, which is submerged or elevated, +but to that part only, which in the immersion is under the first +Levell of the Water, and in the elevation remaines above the first +Levell: Which is that which was to be demonstrated. We will now pursue +the things that remain.</i></p> + +<p>And first we will demonstrate that,</p> +<p><span class="pagenum"><a name="Page_11" id="Page_11">[Pg 11]</a></span></p> + + + + + +<h2><a name="THEOREME_II" id="THEOREME_II"></a>THEOREME II.</h2> + +<div class="sidenote">The proportion of the water abated, to the Solid +raised.</div> + +<p class="def_head"><i>When in one of the above said Vessels, of what ever breadth, +whether wide or narrow, there is placed such a Prisme or +Cylinder, inviron'd with Water, if we elevate that Solid +perpendicularly, the Water circumfused shall abate, and the +Abatement of the Water, shall have the same proportion to the +Elevation of the Prisme, as one of the Bases of the Prisme, hath +to the Surface of the Water Circumfused.</i></p> + + +<div class="figright" style="width: 246px;"> +<img src="images/i013.png" width="246" height="198" alt="" title="" /> +</div> + +<p class="cap">Imagine in the Vessell, as is aforesaid, <a name="tnd_11" id="tnd_11"></a><a href="#tn_11" class="tnlink" title="printer's error, missing letter C in illustration">the Prisme A C D B to be</a> +placed, and in the rest of the Space the Water to be diffused as far +as the Levell E A: and raising the Solid, let it be transferred to G +M, and let the Water be abased from E A to N O: I say, that the +descent of the Water, measured by the Line A O, hath the same +proportion to the rise of the Prisme, measured by the Line G A, as the +Base of the Solid G H hath to the Surface of the Water N O. The which +is manifest: because the Mass of the Solid G A B H, raised above the +first Levell E A B, is equall to the Mass of Water that is abased E N +O A. Therefore, E N O A and G A B H are two equall Prismes; for of +equall Prismes, the Bases answer contrarily to their heights: +Therefore, as the Altitude A O is to the Altitude A G, so is the +Superficies or Base G H to the Surface of the Water N O. If therefore, +for example, a Pillar were erected in a waste Pond full of Water, or +else in a Well, capable of little more then the Mass of the said +Pillar, in elevating the said Pillar, and taking it out of the Water, +according as it riseth, the Water that invirons it will gradually +abate, and the abasement of the Water at the instant of lifting out +the Pillar, shall have the same proportion, that the thickness of the +Pillar hath to the excess of the breadth of the said Pond or Well, +above the thickness of the said Pillar: so that if the breadth of the +Well were an eighth part larger than the thickness of the Pillar, and +the breadth of the Pond twenty five times as great as the said +thickness, in the Pillars ascending one foot, the water in the Well +shall descend seven foot, and that in the Pond only 1/25 of a foot.</p> + +<div class="sidenote">Why a Solid less grave <i>in specie</i> than water, stayeth +not under water, in very small depths:</div> + +<p>This Demonstrated, it will not be difficult to show the true cause, +how it comes to pass, that,</p> +<p><span class="pagenum"><a name="Page_12" id="Page_12">[Pg 12]</a></span></p> + + + + +<h2><a name="THEOREME_III" id="THEOREME_III"></a>THEOREME III.</h2> + +<p class="def_head"><i>A Prisme or regular Cylinder, of a substance specifically less +grave than Water, if it should be totally submerged in Water, +stayes not underneath, but riseth, though the Water circumfused +be very little, and in absolute Gravity, never so much inferiour +to the Gravity of the said Prisme.</i></p> + + +<p class="cap">Let then the Prisme A E F B, be put into the Vessell C D F B, the same +being less grave <i>in specie</i> than the Water: and let the Water infused +rise to the height of the Prisme: I say, that the Prisme left at +liberty, it shall rise, being born up by the Water circumfused C D E +<span class="figleft" style="width: 190px;"> +<img src="images/i014.png" width="190" height="162" alt="" title="" /> +</span> +A. For the Water C E being specifically more grave than the Solid A F, +the absolute weight of the water C E, shall have greater proportion to +the absolute weight of the Prisme A F, than the Mass C E hath to the +Mass A F (in regard the Mass hath the same proportion to the Mass, +that the weight absolute hath to the weight absolute, in case the +Masses are of the same Gravity <i>in specie</i>.) But the Mass C E is to +the Mass A F, as the Surface of the water A C, is to the Superficies, +or Base of the Prisme A B; which is the same proportion as the ascent +of the Prisme when it riseth, hath to the descent of the Water +circumfused C E.</p> + +<p>Therefore, the absolute Gravity of the water C E, hath greater +proportion to the absolute Gravity of the Prisme A F; than the Ascent +of the Prisme A F, hath to the descent of the said water C E. The +Moment, therefore, compounded of the absolute Gravity of the water C +E, and of the Velocity of its descent, whilst it forceably repulseth +and raiseth the Solid A F, is greater than the Moment compounded of +the absolute Gravity of the Prisme A F, and of the Tardity of its +ascent, with which Moment it contrasts and resists the repulse and +violence done it by the Moment of the water: Therefore, the Prisme +shall be raised.</p> + +<div class="sidenote">The Proportion according to which the Submersion & +Natation of Solids is made.</div> + +<p>It followes, now, that we proceed forward to demonstrate more +particularly, how much such Solids shall be inferiour in Gravity to +the water elevated; namely, what part of them shall rest submerged, +and what shall be visible above the Surface of the water: but first it +is necessary to demonstrate the subsequent Lemma.</p> +<p><span class="pagenum"><a name="Page_13" id="Page_13">[Pg 13]</a></span></p> + + + + +<h2><a name="LEMMA_I" id="LEMMA_I"></a>LEMMA I.</h2> + +<div class="sidenote">The absolute Gravity of Solids, are in a proportion +compounded of their Specifick Gravities, and of their Masses.</div> + +<p class="def_head"><i>The absolute Gravities of Solids, have a proportion compounded of +the proportions of their specificall Gravities, and of their +Masses.</i></p> + + +<p class="cap">Let A and B be two Solids. I say, that the Absolute Gravity of A, +hath to the Absolute Gravity of B, a proportion compounded of the +proportions of the specificall Gravity of A, to the Specificall +<span class="figright" style="width: 157px;"> +<img src="images/i015.png" width="157" height="167" alt="" title="" /> +</span> +Gravity of B, and of the Mass A to the Mass B. Let the Line D have the +same proportion to E, that the specifick Gravity of A, hath to the +specifick Gravity of B; and let E be to F, as the Mass A to the Mass +B: It is manifest, that the proportion of D to F, is compounded of the +proportions D and E; and E and F. It is requisite, therefore, to +demonstrate, that as D is to F, so the absolute Gravity of A, is to +the absolute Gravity of B. Take the Solid C, equall in Mass to the +Solid A, and of the same Gravity <i>in specie</i> with the Solid B. +Because, therefore, A and C are equall in Mass, the absolute Gravity +of A, shall have to the absolute Gravity of C, the same proportion, as +the specificall Gravity of A, hath to the specificall Gravity of C, or +of B, which is the same <i>in specie</i>; that is, as D is to E. And, +because, C and B are of the same Gravity <i>in specie</i>, it shall be, +that as the absolute weight of C, is to the absolute weight of B, so +the Mass C, or the Mass A, is to the Mass B; that is, as the Line E to +the Line F. As therefore, the absolute Gravity of A, is to the +absolute Gravity of C, so is the Line D to the Line E: and, as the +absolute Gravity of C, is to the absolute Gravity of B, so is the Line +E to the Line F: Therefore, by Equality of proportion, the absolute +Gravity of A, is to the absolute Gravity of B, as the Line D to the +Line F: which was to be demonstrated. I proceed now to demonstrate, +how that,</p> +<p><span class="pagenum"><a name="Page_14" id="Page_14">[Pg 14]</a></span></p> + + + + +<h2><a name="THEOREME_IV" id="THEOREME_IV"></a>THEOREME IV.</h2> + +<div class="sidenote">The proportion of water requisite to make a Solid +swim:</div> + +<p class="def_head"><i>If a Solid, Cylinder, or Prisme, lesse grave specifically than the +Water, being put into a Vessel, as above, of whatsoever +greatnesse, and the Water, be afterwards infused, the Solid shall +rest in the bottom, unraised, till the Water arrive to that part +of the Altitude, of the said Prisme, to which its whole Altitude +hath the same proportion, that the Specificall Gravity of the +Water, hath to the Specificall Gravity of the said Solid: but +infusing more Water, the Solid shall ascend.</i></p> + + +<p class="cap">Let the Vessell be M L G N of any bigness, and let there be placed in +it the Solid Prisme D F G E, less grave <i>in specie</i> than the water; +and look what proportion the Specificall Gravity of the water, hath to +that of the Prisme, such let the Altitude D F, have to the Altitude F +B. I say, that infusing water to the Altitude F B, the Solid D G shall +not float, but shall stand in <i>Equilibrium</i>, so, that that every +little quantity of water, that is infused, shall raise it. Let the +water, therefore, be infused to the Levell A B C; and; because the +Specifick Gravity of the Solid D G, is to the Specifick Gravity of the +water, as the altitude B F is to the altitude F D; that is, as the +Mass B G to the Mass G D; as the proportion of the Mass B G is to the +Mass G D, as the proportion of the Mass G D is to the Mass A F, they +compose the Proportion of the Mass B G to the Mass A F. Therefore, the +Mass B G is to the Mass A F, in a proportion compounded of the +proportions of the Specifick Gravity of the Solid G D, to the +<span class="figleft" style="width: 183px;"> +<img src="images/i016.png" width="183" height="176" alt="" title="" /> +</span> +Specifick Gravity of the water, and of the Mass G D to the Mass A F: +But the same proportions of the Specifick Gravity of G D, to the +Specifick Gravity of the water, and of the Mass G D to the Mass A F, +do also by the precedent <i>Lemma</i>, compound the proportion of the +absolute Gravity of the Solid D G, to the absolute Gravity of the Mass +of the water A F: Therefore, as the Mass B G is to the Mass A F, so is +the Absolute Gravity of the Solid D G, to the Absolute Gravity of the +Mass of the water A F. But as the Mass B G is to the Mass A F; so is +the Base of the Prisme D E, to the Surface of the water A B; and so is +the descent of the water A B, to the Elevation of the Prisme D G; +<span class="pagenum"><a name="Page_15" id="Page_15">[Pg 15]</a></span> +Therefore, the descent of the water is to the elevation of the Prisme, +as the absolute Gravity of the Prisme, is to the absolute Gravity of +the water: Therefore, the Moment resulting from the absolute Gravity +of the water A F, and the Velocity of the Motion of declination, with +which Moment it forceth the Prisme D G, to rise and ascend, is equall +to the Moment that results from the absolute Gravity of the Prisme D +G, and from the Velocity of the Motion, wherewith being raised, it +would ascend: with which Moment it resists its being raised: because, +therefore, such Moments are equall, there shall be an <i>Equilibrium</i> +between the water and the Solid. And, it is manifest, that putting a +little more water unto the other A F, it will increase the Gravity and +Moment, whereupon the Prisme D G, shall be overcome, and elevated till +that the only part B F remaines submerged. Which is that that was to +be demonstrated.</p> + + +<h3>COROLLARY I.</h3> + +<div class="sidenote"><i>H</i>ow far Solids less grave <i>in specie</i> than water, do +submerge.</div> + +<p class="cor_head"><i>By what hath been demonstrated, it is manifest, that Solids less +grave</i> in specie <i>than the water, submerge only so far, that as +much water in Mass, as is the part of the Solid submerged, doth +weigh absolutely as much as the whole Solid.</i></p> + +<p>For, it being supposed, that the Specificall Gravity of the water, is +to the Specificall Gravity of the Prisme D G, as the Altitude D F, is +to the Altitude F B; that is, as the Solid D G is to the Solid B G; we +might easily demonstrate, that as much water in Mass as is equall to +the Solid B G, doth weigh absolutely as much as the whole Solid D G; +For, by the <i>Lemma</i> foregoing, the Absolute Gravity of a Mass of +water, equall to the Mass B G, hath to the Absolute Gravity of the +Prisme D G, a proportion compounded of the proportions, of the Mass B +G to the Mass G D, <a name="tnd_15" id="tnd_15"></a><a href="#tn_15" class="tnlink" title="printer's error or archaic lettering, final y looking like a 7 in original text">and of the Specifick Gravit{y}</a> of the water, to the +Specifick Gravity of the Prisme: But the Gravity <i>in specie</i> of the +water, to the Gravity <i>in specie</i> of the Prisme, is supposed to be as +the Mass G D to the Mass G B. Therefore, the Absolute Gravity of a +Mass of water, equall to the Mass B G, is to the Absolute Gravity of +the Solid D G, in a proportion compounded of the proportions, of the +Mass B G to the Mass G D, and of the Mass D G to the Mass G B; which +is a proportion of equalitie. The Absolute Gravity, therefore, of a +Mass of Water equall to the part of the Mass of the Prisme B G, is +equall to the Absolute Gravity of the whole Solid D G.</p> +<p><span class="pagenum"><a name="Page_16" id="Page_16">[Pg 16]</a></span></p> + + +<h3>COROLLARY II.</h3> + +<div class="sidenote"><i>A</i> Rule to equilibrate Solids in the water.</div> + +<p class="cor_head"><i>It followes, moreover, that a Solid less grave than the water, +being put into a Vessell of any imaginable greatness, and water +being circumfused about it to such a height, that as much water +in Mass, as is the part of the Solid submerged, do weigh +absolutely as much as the whole Solid; it shall by that water be +justly sustained, be the circumfused Water in quantity greater or +lesser.</i></p> + +<p>For, if the Cylinder or Prisme M, less grave than the water, <i>v. gra.</i> +in Subsequiteriall proportion, shall be put into the capacious Vessell +A B C D, and the water raised about it, to three quarters of its +<span class="figleft" style="width: 411px;"> +<img src="images/i018.png" width="411" height="69" alt="" title="" /> +</span> +height, namely, to its Levell A D: it shall be sustained and exactly +poysed in <i>Equilibrium</i>. The same will happen; <a name="tnd_16b" id="tnd_16b"></a><a href="#tn_16b" class="tnlink" title="letter N for T in text to refer to +illustration">if the Vessell E N S F</a> +were very small, so, that between the Vessell and the Solid M, there +were but a very narrow space, and only capable of so much water, as +the hundredth part of the Mass M, by which it should be likewise +raised and erected, as before it had been elevated to three fourths of +the height of the Solid: which to many at the first sight, may seem a +notable Paradox, and beget a conceit, that the Demonstration of these +effects, were sophisticall and fallacious: but, for those who so +repute it, the Experiment is a means that may fully satisfie them. But +he that shall but comprehend of what Importance Velocity of Motion is, +and how it exactly compensates the defect and want of Gravity, will +cease to wonder, in considering that at the elevation of the Solid M, +the great Mass of water A B C D abateth very little, but the little +Mass of water E N S F decreaseth very much, and in an instant, as the +Solid M before did rise, howbeit for a very short space: Whereupon the +Moment, compounded of the small Absolute Gravity of the water E N S F, +and of its great Velocity in ebbing, <a name="tnd_16" id="tnd_16"></a><a href="#tn_16" class="tnlink" title="printer's error, duplicate word in text">equalizeth the Force and and +Moment,</a> that results from the composition of the immense Gravity of +the water A B C D, with its great slownesse of ebbing; since that in +the Elevation of the Sollid M, the abasement of the lesser water E S, +is performed just so much more swiftly than the great Mass of water A +C, as this is more in Mass than that which we thus demonstrate.</p> + +<div class="sidenote"><i>T</i>he proportion according to which water riseth and +falls in different Vessels at the Immersion and Elevation of +Solids.</div> + +<p>In the rising of the Solid M, its elevation hath the same proportion +to the circumfused water E N S F, that the Surface of the said water, +hath to the Superficies or Base of the said Solid M; which Base hath +the same proportion to the Surface of the water A D, that the +<span class="pagenum"><a name="Page_17" id="Page_17">[Pg 17]</a></span> +abasement or ebbing of the water A C, hath to the rise or elevation of +the said Solid M. Therefore, by Perturbation of proportion, in the +ascent of the said Solid M, the abasement of the water A B C D, to the +abasement of the water E N S F, hath the same proportion, that the +Surface of the water E F, hath to the Surface of the water A D; that +is, that the whole Mass of the water E N S F, hath to the whole Mass A +B C D, being equally high: It is manifest, therefore, that in the +expulsion and elevation of the Solid M, the water E N S F shall exceed +in Velocity of <i>M</i>otion the water A B C D, asmuch as it on the other +side is exceeded by that in quantity: whereupon their Moments in such +operations, are mutually equall.</p> + +<p><i>And, for ampler confirmation, and clearer explication of this, let +us consider the present Figure, (which if I be not deceived, may +serve to detect the errors of some Practick Mechanitians who upon a +false foundation some times attempt impossible enterprizes,) in +which, unto the large Vessell E I D F, the narrow Funnell or Pipe I +C A B is continued, and suppose water infused into them, unto the +Levell L G H, which water shall rest in this position, not without +admiration in some, who cannot conceive how it can be, that the +<span class="figright" style="width: 146px;"> +<img src="images/i019.png" width="146" height="287" alt="" title="" /> +</span> +heavie charge of the great Mass of water G D, pressing downwards, +should not elevate and repulse the little quantity of the other, +contained in the Funnell or Pipe C L, by which the descent of it is +resisted and hindered: But such wonder shall cease, if we begin to +suppose the water G D to be abased only to Q D, and shall +afterwards consider, what the water C L hath done, which to give +place to the other, which is descended from the Levell G H, to the +Levell Q O, shall of necessity have ascended in the same time, from +the Levell L unto A B. And the ascent L B, shall be so much greater +than the descent G Q, by how much the breadth of the Vessell G D, +is greater than that of the Funnell I C; which, in summe, is as +much as the water G D, is more than the water L C: but in regard +that the Moment of the Velocity of the Motion, in one Moveable, +compensates that of the Gravity of another what wonder is it, if +the swift ascent of the lesser Water C L, shall resist the slow +descent of the greater G D?</i></p> + +<p>The same, therefore, happens in this operation, <a name="tnd_17a" id="tnd_17a"></a><a href="#tn_17a" class="tnlink" title="printer's error, rhe for the">as in rhe Stilliard,</a> +in which a weight of two pounds counterpoyseth an other of 200, +<a name="tnd_17b" id="tnd_17b"></a><a href="#tn_17b" class="tnlink" title="missing space between words">asoften as that</a> shall move in the same time, a space 100 times greater +than this: which falleth out when one Arme of the Beam is an hundred +<span class="pagenum"><a name="Page_18" id="Page_18">[Pg 18]</a></span> +times as long as the other. Let the erroneous opinion of those +therefore cease, who hold that a Ship is better, and easier born up in +<span class="sidenote">A ship flotes as well in ten Tun of Water as in an +Ocean.</span> +a great abundance of water, then in a lesser quantity, (<i>this was +believed by</i> Aristotle <i>in his Problems, Sect. 23, Probl. 2.</i>) it being +on the contrary true, that its possible, that a Ship may as well float +in ten Tun of water, as in an Ocean.</p> + +<div class="sidenote">A Solid <a name="tnd_18" id="tnd_18"></a><a href="#tn_18" class="tnlink" title="printer's error, specifiaclly for specifically">specifiaclly</a> graver than the water, cannot be +born up by any quantity of it.</div> + +<p>But following our matter, I say, that by what hath been hitherto +demonstrated, we may understand how, that</p> + + +<h3>COROLLARY III.</h3> + +<p class="cor_head"><i>One of the above named Solids, when more grave</i> in specie <i>than the +water, can never be sustained, by any whatever quantity of it.</i></p> + +<p>For having seen how that the Moment wherewith such a Solid, as grave +<i>in specie</i> as the water, contrasts with the Moment of any Mass of +water whatsoever, is able to retain it, even to its totall Submersion, +without its ever ascending; it remaineth, manifest, that the water is +far less able to raise it up, when it exceeds the same <i>in specie</i>: +so, that though you infuse water till its totall Submersion, it shall +still stay at the Bottome, and with such Gravity, and Resistance to +Elevation, as is the excess of its Absolute Gravity, above the +Absolute Gravity of a Mass equall to it, made of water, or of a Matter +<i>in specie</i> equally grave with the water: and, though you should +moreover adde never so much water above the Levell of that which +equalizeth the Altitude of the Solid, it shall not, for all that, +encrease the Pression, or Gravitation, of the parts circumfused about +the said Solid, by which greater pression, it might come to be +repulsed; because, the Resistance is not made, but only by those parts +of the water, which at the Motion of the said Solid do also move, and +these are those only, which are comprehended by the two Superficies +equidistant to the Horizon, and their parallels, that comprehend the +Altitude of the Solid immerged in the water.</p> + +<p>I conceive, I have by this time sufficiently declared and opened the +way to the contemplation of the true, intrinsecall and proper Causes +of diverse Motions, and of the Rest of many Solid Bodies in diverse +<i>Mediums</i>, and particularly in the water, shewing how all in effect, +depend on the mutuall excesses of the Gravity of the Moveables and of +the <i>Mediums</i>: and, that which did highly import, removing the +Objection, which peradventure would have begotten much doubting, and +scruple in some, about the verity of my Conclusion, namely, how that +notwithstanding, that the excess of the Gravity of the water, above +the Gravity of the Solid, demitted into it, be the cause of its +floating and rising from the Bottom to the Surface, yet a quantity of +water, that weighs not ten pounds, can raise a Solid that weighs above +<span class="pagenum"><a name="Page_19" id="Page_19">[Pg 19]</a></span> +100 pounds: in that we have demonstrated, That it sufficeth, that such +difference be found between the Specificall Gravities of the <i>Mediums</i> +and Moveables, let the particular and absolute Gravities be what they +will: insomuch, that a Solid, provided that it be Specifically less +grave than the water, although its absolute weight were 1000 pounds, +yet may it be born up and elevated by ten pounds of water, and less: +and on the contrary, another Solid, so that it be Specifically more +grave than the water, though in absolute Gravity it were not above a +pound, yet all the water in the Sea, cannot raise it from the Bottom, +or float it. This sufficeth me, for my present occasion, to have, by +the above declared Examples, discovered and demonstrated, without +extending such matters farther, and, as I might have done, into a long +Treatise: yea, but that there was a necessity of resolving the above +proposed doubt, I should have contented my self with that only, which +is demonstrated by <i>Archimedes</i>, in his first <i>Book De Insidentibus +humido</i>: where in generall termes he infers and confirms the same +<span class="sidenote"><i>Of Natation</i> (a) <i>Lib. 1, Prop. 4.</i> (b) <i>Id. Lib. 1. +Prop. 3.</i> (c) <i>Id. Lib. 1. Prop. 3.</i></span> +Conclusions, namely, that Solids (<i>a</i>) less grave than water, swim or +float upon it, the (<i>b</i>) more grave go to the Bottom, and the (<i>c</i>) +equally grave rest indifferently in all places, yea, though they +should be wholly under water.</p> + +<div class="sidenote">The Authors defence of <i>Archimedes</i> his Doctrine, +against the oppositions of <i>Buonamico</i>.</div> + +<p>But, because that this Doctrine of Archimedes, perused, transcribed +and examined by <i>Signor Francesco Buonamico</i>, in his <i>fifth Book of +Motion, Chap. 29</i>, and afterwards by him confuted, might by the +Authority of so renowned, and famous a Philosopher, be rendered +dubious, and suspected of falsity; I have judged it necessary to +defend it, if I am able so to do, and to clear <i>Archimedes</i>, from +those censures, with which he appeareth to be charged. <i>Buonamico</i> +rejecteth the Doctrine of <i>Archimedes</i>, first, as not consentaneous +<span class="sidenote">His first Objection against the Doctrine of +<i>Archimedes</i>.</span> +with the Opinion of <i>Aristotle</i>, adding, that it was a strange thing +to him, that the Water should exceed the Earth in Gravity, seeing on +<span class="sidenote">His Second Objection.</span> +the contrary, that the Gravity of water, increaseth, by means of the +participation of Earth. And he subjoyns presently after, that he was +<span class="sidenote">His third Objection.</span> +not satisfied with the Reasons of <i>Archimedes</i>, as not being able with +that Doctrine, to assign the cause whence it comes, that a Boat and a +Vessell, which otherwise, floats above the water, doth sink to the +Bottom, if once it be filled with water; that by reason of the +equality of Gravity, between the water within it, and the other water +without, it should stay a top; but yet, nevertheless, we see it to go +to the Bottom.</p> + +<p>He farther addes, that <i>Aristotle</i> had clearly confuted the Ancients, +<span class="sidenote">His fourth Objection.</span> +who said, that light Bodies moved upwards, driven by the impulse of +<span class="sidenote">The <i>A</i>ncients denyed <i>A</i>bsolute Levity.</span> +the more grave Ambient: which if it were so, it should seem of +necessity to follow, that all naturall Bodies are by nature heavy, and +<span class="pagenum"><a name="Page_20" id="Page_20">[Pg 20]</a></span> +none light: For that the same would befall the Fire and Air, if put in +the Bottom of the water. And, howbeit, <i>Aristotle</i> grants a Pulsion in +the Elements, by which the Earth is reduced into a Sphericall Figure, +yet nevertheless, in his judgement; it is not such that it can remove +grave Bodies from their naturall places, but rather, that it send them +toward the Centre, to which (as he somewhat obscurely continues to +say,) the water principally moves, if it in the interim meet not with +something that resists it, and, by its Gravity, thrusts it out of its +place: in which case, if it cannot directly, yet at least as well as +it can, it tends to the Centre: but it happens, that light Bodies by +such Impulsion, do all ascend upward: <a name="tnd_20b" id="tnd_20b"></a><a href="#tn_20b" class="tnlink" title="potential printer's error, properly for property">but this properly they have</a> by +nature, as also, that other of swimming. He concludes, lastly, that he +<span class="sidenote">The causes of Natation & Submersion, according to the +Peripateticks.</span> +concurs with <i>Archimedes</i> in his Conclusions; but not in the Causes, +which he would referre to the facile and difficult Separation of the +<i>Medium</i>, and to the predominance of the Elements, so that when the +Moveable superates the power of the <i>Medium</i>; as for example, Lead +doth the Continuity of water, it shall move thorow it, else not.</p> + +<p>This is all that I have been able to collect, as produced against +<i>Archimedes</i> by <i>Signor Buonamico</i>: who hath not well observed the +Principles and Suppositions of <i>Archimedes</i>; which yet must be false, +if the Doctrine be false, which depends upon them; but is contented to +alledge therein some Inconveniences, and some Repugnances to the +Doctrine and Opinion of <i>Aristotle</i>. In answer to which Objections, I +say, first, That the being of <i>Archimedes</i> Doctrine, simply different +<span class="sidenote">The Authors answer to the first Objection.</span> +from the Doctrine of <i>Aristotle</i>, ought not to move any to suspect it, +there being no cause, why the Authority of this should be preferred to +the Authority of the other: but, because, where the decrees of Nature +are indifferently exposed to the intellectuall eyes of each, the +Authority of the one and the other, <a name="tnd_20" id="tnd_20"></a><a href="#tn_20" class="tnlink" title="printer's error, n for u">loseth all a{u}thenticalness</a> of +Perswasion, the absolute power residing in Reason; therefore I pass to +that which he alledgeth in the second place, as an absurd consequent +<span class="sidenote">The Authors answer to the second Objection.</span> +of the Doctrine of <i>Archimedes</i>, namely, That water should be more +grave than Earth. But I really find not, that ever <i>Archimedes</i> said +such a thing, or that it can be rationally deduced from his +Conclusions: and if that were manifest unto me, I verily believe, I +should renounce his Doctrine, as most erroneous. Perhaps this +Deduction of <i>Buonamico</i>, is founded upon that which he citeth of the +Vessel, which swims as long as its voyd of water, but once full it +sinks to the Bottom, and understanding it of a Vessel of Earth, he +infers against <i>Archimedes</i> thus: Thou sayst that the Solids which +swim, are less grave than water: this Vessell swimmeth: therefore, +this Vessell is lesse grave than water. If this be the Illation. I +<span class="pagenum"><a name="Page_21" id="Page_21">[Pg 21]</a></span> +easily answer, granting that this Vessell is lesse grave than water, +and denying the other consequence, namely, that Earth is less Grave +than Water. The Vessel that swims occupieth in the water, not only a +place equall to the Mass of the Earth, of which it is formed; but +equall to the Earth and to the Air together, contained in its +concavity. And, if such a Mass compounded of Earth and Air, shall be +less grave than such another quantity of water, it shall swim, and +shall accord with the Doctrine of <i>Archimedes</i>; but if, again, +removing the Air, the Vessell shall be filled with water, so that the +Solid put in the water, be nothing but Earth, nor occupieth other +place, than that which is only possest by Earth, it shall then go to +the Bottom, by reason that the Earth is heavier than the water: and +this corresponds well with the meaning of <i>Archimedes</i>. See the same +effect illustrated, with such another Experiment, In pressing a Viall +Glass to the Bottom of the water, when it is full of Air, it will meet +with great resistance, because it is not the Glass alone, that is +pressed under water, but together with the Glass a great Mass of Air, +and such, that if you should take as much water, as the Mass of the +Glass, and of the Air contained in it, you would have a weight much +greater than that of the Viall, and of its Air: and, therefore, it +will not submerge without great violence: but if we demit only the +Glass into the water, which shall be when you shall fill the Glass +with water, then shall the Glass descend to the Bottom; as superiour +in Gravity to the water.</p> + +<p>Returning, therefore, to our first purpose; I say, that Earth is more +grave than water, and that therefore, a Solid of Earth goeth to the +bottom of it; but one may possibly make a composition of Earth and +Air, which shall be less grave than a like Mass of Water; and this +shall swim: and yet both this and the other experiment shall very well +accord with the Doctrine of <i>Archimedes</i>. But because that in my +judgment it hath nothing of difficulty in it, I will not positively +affirme that <i>Signor Buonamico</i>, would by such a discourse object unto +<i>Archimedes</i> the absurdity of inferring by his doctrine, that Earth +was less grave than Water, though I know not how to conceive what +other accident he could have induced thence.</p> + +<p>Perhaps such a Probleme (in my judgement false) was read by <i>Signor +Buonamico</i> in some other Author, by whom peradventure it was +attributed as a singular propertie, of some particular Water, and so +comes now to be used with a double errour in confutation of +<i>Archimedes</i>, since he saith no such thing, nor by him that did say it +was it meant of the common Element of Water.</p> + +<div class="sidenote">The Authors answer to the third Objection.</div> + +<p>The third difficulty in the doctrine of <i>Archimedes</i> was, that he +could not render a reason whence it arose, that a piece of Wood, and a +Vessell of Wood, which otherwise floats, goeth to the bottom, if +filled with Water. <i>Signor Buonamico</i> hath supposed that a Vessell of +Wood, and of Wood that by nature swims, as before is said, goes to the +<span class="pagenum"><a name="Page_22" id="Page_22">[Pg 22]</a></span> +bottom, if it be filled with water; of which he in the following +Chapter, which is the 30 of the fifth Book copiously discourseth: but +I (speaking alwayes without diminution of his singular Learning) dare +in defence of <i>Archimedes</i> deny this experiment, being certain that a +piece of Wood which by its nature sinks not in Water, shall not sinke +though it be turned and converted into the forme of any Vessell +whatsoever, and then filled with Water: and he that would readily see +the Experiment in some other tractable Matter, and that is easily +reduced into several Figures, may take pure Wax, and making it first +into a Ball or other solid Figure, let him adde to it so much Lead as +shall just carry it to the bottome, so that being a graine less it +could not be able to sinke it, and making it afterwards into the forme +of a Dish, and filling it with Water, he shall finde that without the +said Lead it shall not sinke, and that with the Lead it shall descend +with much slowness: & in short he shall satisfie himself, that the +Water included makes no alteration. I say not all this while, but that +its possible of Wood to make Barkes, which being filled with water, +sinke; but that proceeds not through its Gravity, encreased by the +Water, but rather from the Nailes and other Iron Workes, so that it no +longer hath a Body less grave than Water, but one mixt of Iron and +Wood, more grave than a like Masse of Water. Therefore let <i>Signor +Buonamico</i> desist from desiring a reason of an effect, that is not in +nature: yea if the sinking of the Woodden Vessell when its full of +Water, may call in question the Doctrine of <i>Archimedes</i>, which he +would not have you to follow, is on the contrary consonant and +agreeable to the Doctrine of the Peripateticks, since it aptly +assignes a reason why such a Vessell must, when its full of Water, +descend to the bottom; converting the Argument the other way, we may +with safety say that the Doctrine of <i>Archimedes</i> is true, since it +aptly agreeth with true experiments, and question the other, whose +Deductions are fastened upon erroneouss Conclusions. As for the other +point hinted in this same Instance, where it <a name="tnd_22" id="tnd_22"></a><a href="#tn_22" class="tnlink" title="printer's error or variation in spelling, Benonamico for Buonamico">seemes that <i>Benonamico</i></a> +understands the same not only of a piece of wood, shaped in the forme +of a Vessell, but also of massie Wood, which filled, <i>scilicet</i>, as I +believe, he would say, soaked and steeped in Water, goes finally to +the bottom that happens in some porose Woods, which, while their +Porosity is replenished with Air, or other Matter less grave than +Water, are Masses specificially less grave than the said Water, like +as is that Viall of Glass whilest it is full of Air: but when, such +light Matter departing, there succeedeth Water into the same +Porosities and Cavities, there results a compound of Water and Glass +more grave than a like Mass of Water: but the excess of its Gravity +consists in the Matter of the Glass, and not in the Water, which +cannot be graver than it self: so that which remaines of the Wood, the +<span class="pagenum"><a name="Page_23" id="Page_23">[Pg 23]</a></span> +Air of its Cavities departing, if it shall be more grave <i>in specie</i> +than Water, fil but its Porosities with Water, and you shall have a +Compost of Water and of Wood more grave than Water, but not by vertue +of the Water received into and imbibed by the Porosities, but of that +Matter of the Wood which remains when the Air is departed: and being +such it shall, according to the Doctrine of <i>Archimedes</i>, goe to the +bottom, like as before, according to the same Doctrine it did swim.</p> + +<div class="sidenote">The Authors answer to the fourth Objection.</div> + +<p>As to that finally which presents itself in the fourth place, +namely, that the <i>Ancients</i> have been heretofore confuted by +<i>Aristotle</i>, who denying Positive and Absolute Levity, and truely +esteeming all Bodies to be grave, said, that that which moved upward +was driven by the circumambient Air, and therefore that also the +Doctrine of <i>Archimedes</i>, as an adherent to such an Opinion was +convicted and confuted: I answer first, that <i>Signor Buonamico</i> in my +judgement hath imposed upon <i>Archimedes</i>, and deduced from his words +more than ever he intended by them, or may from his Propositions be +collected, in regard that <i>Archimedes</i> neither denies, nor admitteth +Positive Levity, nor doth he so much as mention it: so that much less +ought <i>Buonamico</i> to inferre, that he hath denyed that it might be the +Cause and Principle of the Ascension of Fire, and other Light Bodies: +<span class="sidenote">Of Natation, Lib. 1. Prop. 7.</span> +having but only demonstrated, that Solid Bodies more grave than Water +descend in it, according to the excess of their Gravity above the +Gravity of that, he demonstrates likewise, how the less grave ascend +in the same Water, <a name="tnd_23" id="tnd_23"></a><a href="#tn_23" class="tnlink" title="printer's error, missing i">accordng to its excess</a> of Gravity, above the +<span class="sidenote">Of Natation, Lib. 1. Prop. 4.</span> +Gravity of them. So that the most that can be gathered from the +Demonstration of <i>Archimedes</i> is, that like as the excess of the +Gravity of the Moveable above the Gravity of the Water, is the Cause +that it descends therein, so the excess of the Gravity of the water +above that of the Moveable, is a sufficient Cause why it descends not, +but rather betakes it self to swim: not enquiring whether of moving +upwards there is, or is not any other Cause contrary to Gravity: nor +doth <i>Archimedes</i> discourse less properly than if one should say: If +the South Winde shall assault the Barke with greater <i>Impetus</i> than is +the violence with which the Streame of the River carries it towards +the South, the motion of it shall be towards the North: but if the +<i>Impetus</i> of the Water shall overcome that of the Winde, its motion +shall be towards the South. The discourse is excellent and would be +unworthily contradicted by such as should oppose it, saying: Thou +mis-alledgest as Cause of the motion of the Bark towards the South, +the <i>Impetus</i> of the Stream of the Water above that of the South +Winde; mis-alledgest I say, for it is the Force of the North Winde +opposite to the South, that is able to drive the Bark towards the +South. Such an Objection would be superfluous, because he which +alledgeth for Cause of the Motion the Stream of the Water, denies not +<span class="pagenum"><a name="Page_24" id="Page_24">[Pg 24]</a></span> +but that the Winde opposite to the South may do the same, but only +affirmeth that the force of the Water prevailing over the South Wind, +the Bark shall move towards the South: and saith no more than is true. +And just thus when <i>Archimedes</i> saith, that the Gravity of the Water +prevailing over that by which the moveable descends to the Bottom, +such moveable shall be raised from the Bottom to the Surface alledgeth +a very true Cause of such an Accident, nor doth he affirm or deny that +there is, or is not, a vertue contrary to Gravity, called by some +Levity, that hath also a power of moving some Matters upwards. Let +therefore the Weapons of <i>Signor Buonamico</i> be directed against +<i>Plato</i>, and other <i>Ancients</i>, who totally denying <i>Levity</i>, and +<span class="sidenote"><i>Plato</i> denyeth Positive Levity.</span> +taking all Bodies to be grave, say that the Motion upwards is made, +not from an intrinsecal Principle of the Moveable, but only by the +Impulse of the <i>Medium</i>; and let <i>Archimedes</i> and his Doctrine escape +him, since he hath given him no Cause of quarelling with him. But if +this Apologie, produced in defence of <i>Archimedes</i>, should seem to +some insufficient to free him from the Objections and Arguments, +produced by <i>Aristotle</i> against <i>Plato</i>, and the other <i>Ancients</i>, as if +they did also fight against <i>Archimedes</i>, alledging the Impulse of the +Water as the Cause of the swimming of some Bodies less grave than it, +<span class="sidenote">The Authors defence of the doctrine of <i>Plato</i> and the +<i>Ancients</i>, who absolutely deny Levity:</span> +I would not question, but that I should be able to maintaine the +Doctrine of <i>Plato</i> and those others to be most true, who absolutely +deny Levity, and affirm no other Intrinsecal Principle of Motion to be +in Elementary Bodies save only that towards the Centre of the Earth, +<span class="sidenote">According to <i>Plato</i> there is no Principle of the +Motion, of descent in Naturall Bodies, save that to the Centre.</span> +nor no other Cause of moving upwards, speaking of that which hath the +resemblance of natural Motion, but only the repulse of the <i>Medium</i>, +fluid, and exceeding the Gravity of the Moveable: and as to the +<span class="sidenote">No cause of the motion of Ascent, save the Impulse of +the <i>Medium</i>, exceeding the Moveable in Gravitie.</span> +Reasons of <i>Aristotle</i> on the contrary, I believe that I could be able +fully to answer them, and I would assay to do it, if it were +absolutely necessary to the present Matter, or were it not too long a +Digression for this short Treatise. I will only say, that if there +were in some of our Ellementary Bodies an Intrinsecall Principle and +Naturall Inclination to shun the Centre of the Earth, and to move +towards the Concave of the Moon, such Bodies, without doubt, would +more swiftly ascend through those <i>Mediums</i> that least oppose the +Velocity of the Moveable, and these are the more tenuous and subtle; +as is, for example, the Air in comparison of the Water, we daily +proving that we can with farre more expeditious Velocity move a Hand +or a Board to and again in one than in the other: nevertheless, we +<span class="sidenote">Bodies ascend much swifter in the Water, than in the +Air.</span> +never could finde any Body, that did not ascend much more swiftly in +the water than in the Air. Yea of Bodies which we see continually to +ascend in the Water, there is none that having arrived to the confines +of the Air, do not wholly lose their Motion; even the Air it self, +<span class="sidenote">All Bodies ascending through Water, lose their Motion, +comming to the confines of the Air.</span> +which rising with great Celerity through the Water, being once come to + <a name="tnd_24" id="tnd_24"></a><a href="#tn_24" class="tnlink" title="missing line at the end of page in original text">its Region it loseth all</a></p> + +<p><span class="pagenum"><a name="Page_25" id="Page_25">[Pg 25]</a></span></p> +<div class="sidenote">The lighter Bodies ascend more swiftly through Water.</div> + +<p>And, howbeit, Experience shewes, that the Bodies, successively less +grave, do most expeditiously ascend in water, it cannot be doubted, +but that the Ignean Exhalations do ascend more swiftly through the +water, than doth the Air: which Air is seen by Experience to ascend +more swiftly through the Water, than the Fiery Exhalations through the +Air: Therefore, we must of necessity conclude, that the said +<span class="sidenote">Fiery Exhalations ascend thorow the Water more swiftly +than doth the Air; & the Air ascends more swiftly thorow the +Water, than Fire thorow the Air.</span> +Exhalations do much more expeditiously ascend through the Water, than +through the Air; and that, consequently, they are moved by the Impulse +of the Ambient <i>Medium</i>, and not by an intrinsick Principle that is in +them, of avoiding the Centre of the Earth; to which other grave Bodies +tend.</p> + +<div class="sidenote"><i>T</i>he Authors confutation of the Peripateticks Causes +of Natation & Submersion.</div> + +<p>To that which for a finall conclusion, <i>Signor Buonamico</i> produceth +of going about to reduce the descending or not descending, to the +easie and uneasie Division of the <i>Medium</i>, and to the predominancy of +the Elements: I answer, as to the first part, that that cannot in any +manner be admitted as a Cause, being that in none of the Fluid +<i>Mediums</i>, as the Air, the Water, and other Liquids, there is any +Resistance against Division, but all by every the least Force, are +<span class="sidenote">Water & other fluids void of Resistance against +Division.</span> +divided and penetrated, as I will anon demonstrate: so, that of such +Resistance of Division there can be no Act, since it self is not in +being. As to the other part, I say, that the predominancy of the +Elements in Moveables, is to be considered, as far as to the excesse +<span class="sidenote"><i>T</i>he predominancy of Elements in Moveables to be +considered only in relation to their excess or defect of Gravity +in reference to the <i>Medium</i>.</span> +or defect of Gravity, in relation to the <i>Medium</i>: for in that Action, +the Elements operate not, but only, so far as they are grave or light: +therefore, to say that the Wood of the Firre sinks not, because Air +predominateth in it, is no more than to say, because it is less grave +than the Water. Yea, even the immediate Cause, is its being less grave +than the Water: and it being under the predominancy of the Air, is the +<span class="sidenote"><i>T</i>he immediate Cause of Natation is that the Moveable +is less grave than the Water.</span> +Cause of its less Gravity: Therefore, he that alledgeth the +predominancy of the Element for a Cause, brings the Cause of the +Cause, and not the neerest and immediate Cause. Now, who knows not +that the true Cause is the immediate, and not the mediate? Moreover, +<span class="sidenote"><i>T</i>he Peripateticks alledge for the reason of Natation +the Cause of the Cause.</span> +he that alledgeth Gravity, brings a Cause most perspicuous to Sence: +<span class="sidenote">Gravity a Cause most perspicuous to sence.</span> +The cause we may very easily assertain our selves; whether Ebony, for +example, and Firre, be more or less grave than water: but whether +Earth or Air predominates in them, who shall make that manifest? +Certainly, no Experiment can better do it than to observe whether they +swim or sink. So, that he who knows, not whether such a Solid swims, +unless when he knows that Air predominates in it, knows not whether it +swim, unless he sees it swim, for then he knows that it swims, when he +knows that it is Air that predominates, but knows not that Air hath +the predominance, unless he sees it swim: therefore, he knows not if +it swims, till such time as he hath seen it swim.</p> + +<p><span class="pagenum"><a name="Page_26" id="Page_26">[Pg 26]</a></span></p> +<p>Let us not then despise those Hints, though very dark, which Reason, +after some contemplation, offereth to our Intelligence, and lets be +content to be taught by <i>Archimedes</i>, that then any Body shall +submerge in water, when it shall be specifically more grave than it, +<span class="sidenote">Lib 1. of Natation Prop. 7</span> +and that if it shall be less grave, it shall of necessity swim, and +<span class="sidenote">Id. Lib. 1. Prop. 4.</span> +that it will rest indifferently in any place under water, if its +Gravity be perfectly like to that of the water.</p> + +<p>These things explained and proved, I come to consider that which +<span class="sidenote">Id. Lib 1. Prop. 3.</span> +offers it self, touching what the Diversity of figure given unto the +said Moveable hath to do with these Motions and Rests; and proceed to +affirme, that,</p> + + + + +<h2><a name="THEOREME_V" id="THEOREME_V"></a>THEOREME V.</h2> + +<div class="sidenote">Diversity of Figure no Cause of its absolute Natation +or Submersion.</div> + +<p class="def_head"><i>The diversity of Figures given to this or that Solid, cannot any +way be a Cause of its absolute Sinking or Swimming.</i></p> + + +<p class="cap">So that if a Solid being formed, for example, into a Sphericall +Figure, doth sink or swim in the water, I say, that being formed into +any other Figure, the same figure in the same water, shall sink or +swim: nor can such its Motion by the Expansion or by other mutation of +Figure, be impeded or taken away.</p> + +<div class="sidenote">The Expansion of Figure, retards the Velocity of the +ascent or descent of the Moveable in the water; but doth not +deprive it of all Motion.</div> + +<p>The Expansion of the Figure may indeed retard its Velocity, aswell of +ascent as descent, and more and more according as the said Figure is +reduced to a greater breadth and thinness: but that it may be reduced +to such a form as that that same matter be wholly hindred from moving +in the same water, that I hold to be impossible. In this I have met +with great contradictors, who producing some Experiments, and in +perticular a thin Board of Ebony, and a Ball of the same Wood, and +shewing how the Ball in Water descended to the bottom, and the Board +being put lightly upon the Water submerged not, but rested; have held, +and with the Authority of <i>Aristotle</i>, confirmed themselves in their +Opinions, that the Cause of that Rest was the breadth of the Figure, +<a name="tnd_26" id="tnd_26"></a><a href="#tn_26" class="tnlink" title="missing letter n">u{n}able by its small weight</a> to pierce and penetrate the Resistance of +the Waters Crassitude, which Resistance is readily overcome by the +other Sphericall Figure.</p> + +<p>This is the Principal point in the present Question, in which I +perswade my self to be on the right side.</p> + +<p>Therefore, beginning to investigate with the examination of exquisite +Experiments that really the Figure doth not a jot alter the descent or +Ascent of the same Solids, and having already demonstrated that the +greater or less Gravity of the Solid in relation to the Gravity of the +<i>Medium</i> is the cause of Descent or Ascent: when ever we would make +<span class="pagenum"><a name="Page_27" id="Page_27">[Pg 27]</a></span> +proof of that, which about this Effect the diversity of Figure +worketh, its necessary to make the Experiment with Matter wherein +variety of Gravities hath no place. For making use of Matters which +may be different in their Specifical Gravities, and meeting with +varieties of effects of Ascending and Descending, we shall alwayes be +left unsatisfied whether that diversity derive it self really from the +sole Figure, or else from the divers Gravity also. We may remedy this +by takeing one only Matter, that is tractable and easily reduceable +into every sort of Figure. Moreover, it will be an excellent expedient +to take a kinde of Matter, exactly alike in Gravity unto the Water: +for that Matter, as far as pertaines to the Gravity, is indifferent +either to Ascend or Descend; so that we may presently observe any the +least difference that derives it self from the diversity of Figure.</p> + +<div class="sidenote">An Experiment in Wax, that proveth Figure to have no +Operation in Natation & Submersion.</div> + +<p>Now to do this, Wax is most apt, which, besides its incapacity of +receiveing any sensible alteration from its imbibing of Water, is +ductile or pliant, and the same piece is easily reduceable into all +Figures: and being <i>in Specie</i> a very inconsiderable matter inferiour +in Gravity to the Water, by mixing therewith a little of the fileings +of Lead it is reduced to a Gravity exactly equall to that of the +Water.</p> + +<p>This Matter prepared, and, for example, a Ball being made thereof as +bigge as an Orange or biger, and that made so grave as to sink to the +bottom, but so lightly, that takeing thence one only Grain of Lead, it +returns to the top, and being added, it submergeth to the bottom, let +the same Wax afterwards be made into a very broad and thin Flake or +Cake; and then, returning to make the same Experiment, you shall see +that it being put to the bottom, it shall, with the Grain of Lead rest +below, and that Grain deducted, it shall ascend to the very Surface, +and added again it shall dive to the bottom. And this same effect +shall happen alwaies in all sort of Figures, as wel regular as +irregular: nor shall you ever finde any that will swim without the +removall of the Grain of Lead, or sinke to the bottom unless it be +added: and, in short, about the going or not going to the Bottom, you +shall discover no diversity, although, indeed, you shall about the +quick and slow descent: for the more expatiated and distended Figures +move more slowly aswel in the diveing to the bottom as in the rising +to the top; and the other more contracted and compact Figures, more +speedily. Now I know not what may be expected from the diversity of +Figures, if the most contrary to one another operate not so much as +doth a very small Grain of Lead, added or removed.</p> + +<div class="sidenote">An objection against the Experiment in Water.</div> + +<p>Me thinkes I hear some of the Adversaries to raise a doubt upon my +produced Experiment. And first that they offer to my consideration, +that the Figure, as a Figure simply, and disjunct from the Matter +workes not any effect, but requires to be conjoyned with the Matter; +<span class="pagenum"><a name="Page_28" id="Page_28">[Pg 28]</a></span> +and, furthermore, not with every Matter, but with those only, +wherewith it may be able to execute the desired operation. Like as we +see it verified by Experience, that the Acute and sharp Angle is more +apt to cut, than the Obtuse; yet alwaies provided, that both the one +and the other, be joyned with a Matter apt to cut, as for example, +with Steel. Therefore, a Knife with a fine and sharp edge, cuts Bread +or Wood with much ease, which it will not do, if the edge be blunt and +thick: but he that will instead of Steel, take Wax, and mould it into +a Knife, undoubtedly shall never know the effects of sharp and blunt +edges: because neither of them will cut, the Wax being unable by +reason of its flexibility, to overcome the hardness of the Wood and +Bread. And, therefore, applying the like discourse to our purpose, +they say, that the difference of Figure will shew different effects, +touching Natation and Submersion, but not conjoyned with any kind of +Matter, but only with those Matters which, by their Gravity, are apt +to resist the Velocity of the water, whence he that would elect for +the Matter, Cork or other light wood, unable, through its Levity, to +superate the Crassitude of the water, and of that Matter should forme +Solids of divers Figures, would in vain seek to find out what +operation Figure hath in Natation or Submersion; because all would +swim, and that not through any property of this or that Figure, but +through the debility of the Matter, wanting so much Gravity, as is +requisite to superate and overcome the Density and Crassitude of the +water.</p> + +<p>Its needfull, therefore, if wee would see the effect wrought by the +Diversity of Figure, first to make choice of a Matter of its nature +apt to penetrate the Crassitude of the water. And, for this effect, +<span class="sidenote">An Experiment in Ebany, brought to disprove the +Experiment in Wax.</span> +they have made choice of such a Matter, as fit, that being readily +reduced into Sphericall Figure, goes to the Bottom; and it is Ebony, +of which they afterwards making a small Board or Splinter, as thin as +a Lath, have illustrated how that this, put upon the Surface of the +water, rests there without descending to the Bottom: and making, on +the otherside, of the same wood a Ball, no less than a hazell Nut, +they shew, that this swims not, but descendes. From which Experiment, +they think they may frankly conclude, that the Breadth of the Figure +in the flat Lath or Board, is the cause of its not descending to the +Bottom, for as much as a Ball of the same Matter, not different from +the Board in any thing but in Figure, submergeth in the same water to +the Bottom. The discourse and the Experiment hath really so much of +probability and likelyhood of truth in it, that it would be no wonder, +if many perswaded by a certain cursory observation, should yield +credit to it; nevertheless, I think I am able to discover, how that it +is not free from falacy.</p> + +<p>Beginning, therefore, to examine one by one, all the particulars that +<span class="pagenum"><a name="Page_29" id="Page_29">[Pg 29]</a></span> +have been produced, I say, that Figures, as simple Figures, not only +operate not in naturall things, but neither are they ever seperated +from the Corporeall substance: nor have I ever alledged them stript of +<span class="sidenote">Figure is unseperable from Corporeall Substance.</span> +sensible Matter, like as also I freely admit, that in our endeavouring +to examine the Diversity of Accidents, dependant upon the variety of +Figures, it is necessary to apply them to Matters, which obstruct not +the various operations of those various Figures: and I admit and +grant, that I should do very ill; if I would experiment the influence +of Acutenesse of edge with a Knife of Wax, applying it to cut an Oak, +because there is no Acuteness in Wax able to cut that very hard wood. +But yet such an Experiment of this Knife, would not be besides the +purpose, to cut curded Milk, or other very yielding Matter: yea, in +such like Matters, the Wax is more commodious than Steel; for finding +the diversity depending upon Angles, more or less Acute, for that Milk +is indifferently cut with a Raisor, and with a Knife, that hath a +blunt edge. It needs, therefore, that regard be had, not only to the +hardness, solidity or Gravity of Bodies, which under divers figures, +are to divide and penetrate some Matters, but it forceth also, that +regard be had, on the other side, to the Resistance of the Matters, to +be divided and penetrated. But since I have in making the Experiment +concerning our Contest; chosen a Matter which penetrates the +Resistance of the water; and in all figures descendes to the Bottome, +the Adversaries can charge me with no defect; yea, I have propounded +so much a more excellent Method than they, in as much as I have +removed all other Causes, of descending or not descending to the +Bottom, and retained the only sole and pure variety of Figures, +demonstrating that the same Figures all descende with the only +alteration of a Grain in weight: which Grain being removed, they +return to float and swim; it is not true, therefore, (resuming the +Example by them introduced) <a name="tnd_29" id="tnd_29"></a><a href="#tn_29" class="tnlink" title="missing letter e">that I have gon{e} about</a> to experiment the +efficacy of Acuteness, in cutting with Matters unable to cut, but with +Matters proportioned to our occasion, since they are subjected to no +other variety, then that alone which depends on the Figure more or +less acute.</p> + +<div class="sidenote">The answer to the Objection against the Experiment of +the Wax.</div> + +<p>But let us proceed a little farther, and observe, how that indeed the +Consideration, which, they say, ought to be had about the Election of +the Matter, to the end, that it may be proportionate for the making of +our experiment, is needlessly introduced, declaring by the example of +Cutting, that like as Acuteness is inefficient to cut, unless when it +is in a Matter hard and apt to superate the Resistance of the wood or +other Matter, which we intend to cut; so the aptitude of descending or +not descending in water, ought and can only be known in those Matters, +that are able to overcome the Renitence, and superate the Crassitude +of the water. Unto which, I say, that to make distinction and +election, more of this than of that Matter, on which to impress the +<span class="pagenum"><a name="Page_30" id="Page_30">[Pg 30]</a></span> +Figures for cutting or penetrating this or that Body, as the solidity +or obdurateness of the said Bodies shall be greater or less, is very +necessary: but withall I subjoyn, that such distinction, election and +caution would be superfluous and unprofitable, if the Body to be cut +or penetrated, should have no Resistance, or should not at all +withstand the Cutting or Penitration: and if the Knife were to be used +in cutting a Mist or Smoak, one of Paper would be equally serviceable +with one of <i>Damascus</i> Steel: and so by reason the water hath not any +Resistance against the Penitration of any Solid Body, all choice of +Matter is superfluous and needless, and the Election which I said +above to have been well made of a Matter reciprocall in Gravity to +water, was not because it was necessary, for the overcoming of the +crassitude of the water, but its Gravity, with which only it resists +the sinking of Solid Bodies: and for what concerneth the Resistance of +the crassitude, if we narrowly consider it, we shall find that all +Solid Bodies, as well those that sink, as those that swim, are +indifferently accomodated and apt to bring us to the knowledge of the +truth in question. Nor will I be frighted out of the belief of these +Conclusions, by the Experiments which may be produced against me, of +many severall Woods, Corks, Galls, and, moreover, of subtle slates and +plates of all sorts of Stone and Mettall, apt by means of their +Naturall Gravity, to move towards the Centre of the Earth, the which, +nevertheless, being impotent, either through the Figure (as the +Adversaries thinke) or through Levity, to break and penetrate the +Continuity of the parts of the water, and to distract its union, do +continue to swimm without submerging in the least: nor on the other +side, shall the Authority of <i>Aristotle</i> move me, who in more than one +place, affirmeth the contrary to this, which Experience shews me.</p> + +<div class="sidenote">No Solid of such Levity, nor of such Figure, but that +it doth penetrate the Crassitude of the Water.</div> + +<div class="sidenote">Bodies of all Figures, laid upon the water, do +penetrate its Crassitude, and in what proportion.</div> + +<p>I return, therefore, to assert, that there is not any Solid of such +Levity, nor of such Figure, that being put upon the water, doth not +divide and penetrate its Crassitude: yea if any with a more +perspicatious eye, shall return to observe more exactly the thin +Boards of Wood, he shall see them to be with part of their thickness +under water, and not only with their inferiour Superficies, to kisse +the Superiour of the water, as they of necessity must have believed, +who have said, that such Boards submerge not, as not being able to +divide the Tenacity of the parts of the water: and, moreover, he shall +see, that subtle shivers of Ebony, Stone or Metall, when they float, +have not only broak the Continuity of the water, but are with all +their thickness, under the Surface of it; and more and more, according +as the Matters are more grave: so that a thin Plate of Lead, shall be +lower than the Surface of the circumfused water, by at least twelve +times the thickness of the Plate, and Gold shall dive below the Levell +<span class="pagenum"><a name="Page_31" id="Page_31">[Pg 31]</a></span> +of the water, almost twenty times the thickness of the Plate, as I +shall anon declare.</p> + +<p>But let us proceed to evince, that the water yields and suffers it +self to be penetrated by every the lightest Body; and therewithall +demonstrate, how, even by Matters that submerge not, we may come to +know that Figure operates nothing about the going or not going to the +Bottom, seeing that the water suffers it self to be penetrated equally +by every Figure.</p> + +<div class="sidenote">The Experiment of a Cone, demitted with its Base, and +after with its Point downwards.</div> + +<p>Make a Cone, or a Piramis of Cypress, of Firre, or of other Wood of +like Gravity, or of pure Wax, and let its height be somewhat great, +namely a handfull, or more, and put it into the water with the Base +downwards: first, you shall see that it will penetrate the water, nor +shall it be at all impeded by the largeness of the Base, nor yet shall +it sink all under water, but the part towards the point shall lye +above it: by which shall be manifest, first, that that Solid forbeares +not to sink out of an inability to divide the Continuity of the water, +having already divided it with its broad part, that in the opinion of +the Adversaries is the less apt to make the division. The Piramid +being thus fixed, note what part of it shall be submerged, and revert +it afterwards with the point downwards, and you shall see that it +shall not dive into the water more than before, but if you observe how +far it shall sink, every person expert in Geometry, may measure, that +those parts that remain out of the water, both in the one and in the +other Experiment are equall to an hair: whence he may manifestly +conclude, that the acute Figure which seemed most apt to part and +penetrate the water, doth not part or penetrate it more than the large +and spacious.</p> + +<p>And he that would have a more easie Experiment, let him take two +Cylinders of the same Matter, one long and small, and the other short, +but very broad, and let him put them in the water, not distended, but +erect and endways: he shall see, if he diligently measure the parts of +the one and of the other, that in each of them the part submerged, +retains exactly the same proportion to that out of the water, and that +no greater part is submerged of that long and small one, than of the +other more spacious and broad: howbeit, this rests upon a very large, +and that upon a very little Superficies of water: therefore the +diversity of Figure, occasioneth neither facility, nor difficulty, in +parting and penetrating the Continuity of the water, and, +consequently, cannot be the Cause of the Natation or Submersion. He +may likewise discover the non operating of variety of Figures, in +arising from the Bottom of the water, towards the Surface, by taking +Wax, and tempering it with a competent quantity of the filings of +Lead, so that it may become a considerable matter graver than the +<span class="pagenum"><a name="Page_32" id="Page_32">[Pg 32]</a></span> +water: then let him make it into a Ball, and thrust it unto the Bottom +of the water; and fasten to it as much Cork, or other light matter, as +just serveth to raise it, and draw it towards the Surface: for +afterwards changing the same Wax into a thin Cake, or into any other +Figure, that same Cork shall raise it in the same manner to a hair.</p> + +<p>This silenceth not my Antagonists, but they say, that all the +discourse hitherto made by me little importeth to them, and that it +serves their turn, that they have demonstrated in one only particular, +and in what matter, and under what Figure pleaseth them, namely, in a +Board and in a Ball of Ebony, that this put in the water, descends to +the Bottom, and that stays atop to swim: and the Matter being the +same, and the two Bodies differing in nothing but in Figure, they +affirm, that they have with all perspicuity demonstrated and sensibly +manifested what they undertook; and lastly, that they have obtained +their intent. Nevertheless, I believe, and thinke, I can demonstrate, +that that same Experiment proveth nothing against my Conclusion.</p> + +<div class="sidenote">In Experiments of Natation, the Solid is to be put +into, not upon the water.</div> + +<p>And first, it is false, that the Ball descends, and the Board not: for +the Board shall also descend, if you do to both the Figures, as the +words of our Question requireth; that is, if you put them both into +the water.</p> + +<div class="sidenote">The Question of Natation stated.</div> + +<p><i>The words were these. That the Antagonists having an opinion, that +the Figure would alter the Solid Bodies, in relation to the +descending or not descending, ascending or not ascending in the +same</i> Medium, <i>as</i> v. gr. <i>in the same water, in such sort, that, for +Example, a Solid that being of a Sphericall Figure, shall descend +to the Bottom, being reduced into some other Figure, shall not +descend: I holding the contrary, do affirm, that a Corporeall Solid +Body, which reduced into a Sphericall Figure, or any other, shall +go to the Bottom, shall do the like under whatsoever <a name="tnd_32" id="tnd_32"></a><a href="#tn_32" class="tnlink" title="unclear symbol in original text">other Figure, +{&}c.</a></i></p> + +<div class="sidenote">Place defined according to Aristotle.</div> + +<p>But to be in the water, implies to be placed in the water, and by +<i>Aristotles</i> own Definition of place, to be placed, importeth to be +invironed by the Superficies of the Ambient Body, therefore, then +shall the two Figures be in the water, when the Superficies of the +water, shall imbrace and inviron them: but when the Adversaries shew +the Board of Ebony not descending to the Bottom, they put it not into +the water, but upon the water, where being by a certain impediment (as +by and by we will shew) retained, it is invironed, part by water, and +part by air, which thing is contrary to our agreement, that was, that +the Bodies should be in the water, and not part in water, and part in +air.</p> + +<p><span class="pagenum"><a name="Page_33" id="Page_33">[Pg 33]</a></span></p> +<p><i>The which is again made manifest, by the questions being put as +well about the things which go to the Bottom, as those which arise +from the Bottom to swimme, and who sees not that things placed in +the Bottom, must have water about them.</i></p> + +<div class="sidenote">The confutation of the Experiment in the Ebany.</div> + +<p>It is now to be noted, that the Board of Ebany and the Ball, put into +the water, both sink, but the Ball more swiftly, and the Board more +slowly; and slower and slower, according as it shall be more broad and +thin, and of this Tardity the breadth of the Figure is the true Cause: +But these broad Boards that slowly descend, are the same, that being +put lightly upon the water, do swimm: Therefore, if that were true +which the Adversaries affirm, the same numerical Figure, would in the +same numericall water, cause one while Rest, and another while Tardity +of Motion, which is impossible: for every perticular Figure which +descends to the Bottom, hath of necessity its own determinate Tardity +<span class="sidenote">Every perticular Figure hath its own peculiar Tardity.</span> +and slowness, proper and naturall unto it, according to which it +moveth, so that every other Tardity, greater or lesser is improper to +its nature: if, therefore, a Board, as suppose of a foot square, +descendeth naturally with six degrees of Tardity, it is impossible, +that it should descend with ten or twenty, unless some new impediment +do arrest it. Much less can it, by reason of the same Figure rest, and +wholly cease to move; but it is necessary, that when ever it resteth, +there do some greater impediment intervene than the breadth of the +Figure. Therefore, it must be somewhat else, and not the Figure, that +stayeth the Board of Ebany above water, of which Figure the only +Effect is the retardment of the Motion, according to which it +descendeth more slowly than the Ball. Let it be confessed, therefore, +rationally discoursing, that the true and sole Cause of the Ebanys +going to the Bottom, is the excess of its Gravity above the Gravity of +the water: and the Cause of the greater or less Tardity, the breadth +of this Figure, or the contractedness of that: but of its Rest, it can +by no means be allowed, that the quallity of the Figure, is the Cause +thereof: aswell, because, making the Tardity greater, according as the +Figure more dilateth, there cannot be so immense a Dilatation, to +which there may not be found a correspondent immence Tardity without +redusing it to Nullity of Motion; as, because the Figures produced by +the Antagonists for effecters of Rest, are the self same that do also +go to the Bottom.</p> + +<div class="sidenote">* The Figure & Resistance of the Medium against +Division, have nothing to do with the Effect of Natation or +Submersion, by an Experiment in Wallnut tree.</div> + +<p>I will not omit another reason, founded also upon Experience, and if +I deceive not my self, manifestly concluding, how that the +Introduction of the breadth or amplitude of Figure, and the Resistance +of the water against penetration, have nothing to do in the Effect of +descending, or ascending, or resting in the water. *Take a piece of +wood or other Matter, of which a Ball ascends from the Bottom of the +<span class="pagenum"><a name="Page_34" id="Page_34">[Pg 34]</a></span> +water to the Surface, more slowly than a Ball of Ebony of the same +bignesse, so that it is manifest, that the Ball of Ebony more readily +divideth the water in descending, than the other in ascending; as for +Example, let the Wood be Walnut-tree. Then take a Board of +Walnut-tree, like and equall to that of Ebony of the Antagonists, +which swims; and if it be true, that this floats above water, by +reason of the Figure, unable through its breadth, to pierce the +Crassitude of the same, the other of Wallnut-tree, without all +question, being thrust unto the Bottom, will stay there, as less apt, +through the same impediment of Figure, to divide the said Resistance +of the water. But if we shall find, and by experience see, that not +only the thin Board, but every other Figure of the same Wallnut-tree +will return to float, as undoubtedly we shall, then I must desier my +opposers to forbear to attribute the floating of the Ebony, unto the +Figure of the Board, in regard that the Resistance of the water is the +same, as well to the ascent, as to the descent, and the force of the +Wallnut-trees ascension, is lesse than the Ebonys force in going to +the Bottom.</p> + +<div class="sidenote">An Experiment in Gold, to prove the non-operating of +Figure in Natation and Submersion.</div> + +<p>Nay, I will say more, that if we shall consider Gold in comparison of +water, we shall find, that it exceeds it in Gravity almost twenty +times, so that the Force and Impetus, wherewith a Ball of Gold goes to +the Bottom, is very great. On the contrary, there want not matters, as +Virgins Wax, and some Woods, which are not above a fiftieth part less +grave than water, whereupon their Ascension therein is very slow, and +a thousand times weaker than the <i>Impetus</i> of the Golds descent: yet +notwithstanding, a plate of Gold swims without descending to the +Bottom, and, on the contrary, we cannot make a Cake of Wax, or thin +Board of Wood, which put in the Bottom of the Water, shall rest there +without ascending. Now if the Figure can obstruct the Penetration, and +impede the descent of Gold, that hath so great an <i>Impetus</i>, how can +it choose but suffice to resist the same Penetration of the other +matter in ascending, when as it hath scarce a thousandth part of the +<i>Impetus</i> that the Gold hath in descending? Its therefore, necessary, +that that which suspends the thin Plate of Gold, or Board of Ebony, +upon the water, be some thing that is wanting to the other Cakes and +Boards of Matters less grave than the water; since that being put to +the Bottom, and left at liberty, they rise up to the Surface, without +any obstruction: But they want not for flatness and breadth of Figure: +Therefore, the *spaciousnesse of the Figure, is not that which makes +the Gold and Ebony to swim.</p> + +<p>And, because, that the excess of their Gravity above the Gravity of +the water, is questionless the Cause of the sinking of the flat piece +of Ebony, and the thin Plate of Gold, when they go to the Bottom, +therefore, of necessity, when they float, the Cause of their staying +above water, proceeds from Levity, which in that case, by some +<span class="pagenum"><a name="Page_35" id="Page_35">[Pg 35]</a></span> +Accident, peradventure not hitherto observed, cometh to meet with the +said Board, rendering it no longer as it was before, whilst it did +sink more ponderous than the water, but less.</p> + +<p>Now, let us return to take the thin Plate of Gold, or of Silver, or +the thin Board of Ebony, and let us lay it lightly upon the water, so +that it stay there without sinking, and diligently observe its effect. +And first, see how false the assertion of <i>Aristotle</i>, and our +oponents is, to wit, that it stayeth above water, through its +unability to pierce and penetrate the Resistance of the waters +Crassitude: for it will manifestly appear, not only that the said +Plates have penetrated the water, but also that they are a +considerable matter lower than the Surface of the same, the which +continueth eminent, and maketh as it were a Rampert on all sides, +round about the said Plates, the profundity of which they stay +swimming: and, according as the said Plates shall be more grave than +the water, two, four, ten or twenty times, it is necessary, that their +Superficies do stay below the universall Surface of the water, so much +more, than the thickness of those Plates, as we shal more distinctly +shew anon. In the mean space, for the more easie understanding of what +<span class="figright" style="width: 277px;"> +<img src="images/i037.png" width="277" height="136" alt="" title="" /> +</span> +I say, observe with me a little the present Scheme: in which let us +suppose the Surface of the water to be distended, according to the +Lines F L D B, upon which if one shall put a board of matter +specifically more grave than water, but so lightly that it submerge +not, it shall not rest any thing above, but shall enter with its whole +thickness into the water: and, moreover, shall sink also, as we see by +the Board A I, O I, whose breadth is wholly sunk into the water, the +little Ramperts of water L A and D O incompassing it, whose +Superficies is notably higher than the Superficies of the Board. See +now whether it be true, that the said Board goes not to the Bottom, as +being of Figure unapt to penetrate the Crassitude of the water.</p> + +<div class="sidenote">Why solids having penitrated the Water, do not proceed +to a totall Submersion.</div> + +<p>But, if it hath already penetrated, and overcome the Continuity of +the water, & is of its own nature more grave than the said water, why +doth it not proceed in its sinking, but stop and suspend its self +within that little dimple or cavitie, which with its ponderosity it +hath made in the water? I answer; because that in submerging it self, +so far as till its Superficies come to the Levell with that of the +water, it loseth a part of its Gravity, and loseth the rest of it as +it submergeth & descends beneath the Surface of the water, which +maketh Ramperts and Banks round about it, and it sustaines this loss +by means of its drawing after it, and carrying along with it, the Air +that is above it, and by Contact adherent to it, which Air succeeds to +fill the Cavity that is invironed by the Ramperts of water; so that +that which in this case descends and is placed in the water, is not +only the Board of Ebony or Plate of Iron, but a composition of Ebony +<span class="pagenum"><a name="Page_36" id="Page_36">[Pg 36]</a></span> +and Air, from which resulteth a Solid no longer superiour in Gravity +to the water, as was the simple Ebony, or the simple Gold. And, if we +exactly consider, what, and how great the Solid is, that in this +Experiment enters into the water, and contrasts with the Gravity of +the same, it will be found to be all that which we find to be beneath +the Surface of the water, the which is an aggregate and Compound of a +Board of Ebony, and of almost the like quantity of Air, or a Mass +compounded of a Plate of Lead, and ten or twelve times as much Air. +But, Gentlemen, you that are my Antagonists in our Question, we +require the Identity of Matter, and the alteration only of the Figure; +therefore, you must remove that Air, which being conjoyned with the +Board, makes it become another Body less grave than the Water, and put +only the Ebony into the Water, and you shall certainly see the Board +descend to the Bottom; and, if that do not happen, you have got the +day. And to seperate the Air from the Ebony, there needs no more but +<span class="sidenote">How to seperate the Air from Solids in demitting them +into the water.</span> +only to bath the Superficies of the said Board with the same Water: +for the Water being thus interposed between the Board and the Air, the +other circumfused Water shall run together without any impediment, and +shall receive into it the sole and bare Ebony, as it was to do.</p> + +<p>But, me thinks I hear some of the Adversaries cunningly opposing this, +and telling me, that they will not yield, by any means, that their +Board be wetted, because the weight added thereto by the Water, by +making it heavier than it was before, draws it to the Bottom, and that +the addition of new weight is contrary to our agreement, which was, +that the Matter be the same.</p> + +<p>To this, I answer, first; that treating of the operation of Figure +in Bodies put into the Water, none can suppose them to be put into the +Water without being wet; nor do I desire more to be done to the Board, +then I will give you leave to do to the Ball. Moreover, it is untrue, +that the Board sinks by vertue of the new Weight added to it by the +Water, in the single and slight bathing of it: for I will put ten or +twenty drops of Water upon the same Board, whilst it is sustained upon +the water; which drops, because not conjoyned with the other Water +circumfused, shall not so encrease the weight of it, as to make it +sink: but if the Board being taken out, and all the water wiped off +that was added thereto, I should bath all its Superficies with one +only very small drop, and put it again upon the water, without doubt +it shall sink, the other Water running to cover it, not being retained +by the superiour Air; which Air by the interposition of the thin vail +of water, that takes away its Contiguity unto the Ebony, shall without +Renitence be seperated, nor doth it in the least oppose the succession +of the other Water: but rather, to speak better, it shall descend +freely; because it shall be all invironed and covered with water, as +<span class="pagenum"><a name="Page_37" id="Page_37">[Pg 37]</a></span> +soon as its superiour Superficies, before vailed with water, doth +arrive to the Levell of the universall Surface of the said water. To +say, in the next place, that water can encrease the weight of things +that are demitted into it, is most false; for water hath no Gravity in +water, since it descends not: yea, if we would well consider what any +<span class="sidenote">Water hath no Gravity in Water.</span> +immense Mass of water doth put upon a grave Body; that is placed in +it, we shall find experimentally, that it, on the contrary, will +rather in a great part deminish the weight of it, and that we may be +<span class="sidenote">Water deminisheth the Gravity of Solids immerged +therein.</span> +able to lift an huge Stone from the Bottom of the water, which the +water being removed, we are not able to stir. Nor let them tell me by +way of reply, that although the superposed water augment not the +Gravity of things that are in it, yet it increaseth the ponderosity of +those that swim, and are part in the water and part in the Air, as is +seen, for Example, in a Brass Ketle, which whilst it is empty of +<span class="sidenote">The Experiment of a brass Ketle swiming when empty, & +sinking when full, alledged to prove that water gravitates in +water, answered.</span> +water, and replenished only with Air shall swim, but pouring of Water +therein, it shall become so grave, that it shall sink to the Bottom, +and that by reason of the new weight added thereto. To this I will +return answer, as above, that the Gravity of the Water, contained in +the Vessel is not that which sinks it to the Bottom, but the proper +Gravity of the Brass, superiour to the Specificall Gravity of the +Water: for if the Vessel were less grave than water, the Ocean would +not suffice to submerge it. And, give me leave to repeat it again, as +<span class="sidenote">An Ocean sufficeth not to sink a Vessel specifically +less grave than water.</span> +the fundamentall and principall point in this Case, that the Air +contained in this Vessel before the infusion of the Water, was that +which kept it a-float, since that there was made of it, and of the +<span class="sidenote">Air, the Cause of the Natation of empty Vessels of +Matters graver <i>in specie</i> than the water.</span> +Brass, a Composition less grave than an equall quantity of Water: and +the place that the Vessel occupyeth in the Water whilst it floats, is +not equall to the Brass alone, but to the Brass and to the Air +together, which filleth that part of the Vessel that is below the +Levell of the water: Moreover, when the Water is infused, the Air is +removed, and there is a composition made of Brass and of water, more +grave <i>in specie</i> than the simple water, but not by vertue of the +water infused, as having greater Specifick Gravity than the other +water, but through the proper Gravity of the Brass, and through the +alienation of the Air. Now, as he that should say that Brass, that by +its nature goes to the Bottom, being formed into the Figure of a +Ketle, acquireth from that Figure a vertue of lying in the Water +<span class="sidenote">Neither Figure, nor the breadth of Figure, is the Cause +of Natation.</span> +without sinking, would say that which is false; because that Brass +fashioned into any <a name="tnd_37" id="tnd_37"></a><a href="#tn_37" class="tnlink" title="potential printer's error, comma in unusual position">whatever Figure, goeth always</a> to the Bottom, +provided, that that which is put into the water be simple Brass; and +it is not the Figure of the Vessel that makes the Brass to float, but +it is because that that is not purely Brass which is put into the +water, but an aggregate of Brass and of Air: so is it neither more nor +<span class="pagenum"><a name="Page_38" id="Page_38">[Pg 38]</a></span> +less false, that a thin Plate of Brass or of Ebony, swims by vertue of +its dilated & broad Figure: for the truth is, that it bares up without +submerging, because that that which is put in the water, is not pure +Brass or simple Ebony, but an aggregate of Brass and Air, or of Ebony +and Air. And, this is not contrary unto my Conclusion, the which, +(having many a time seen Vessels of Mettall, and thin pieces of +diverse grave Matters float, by vertue of the Air conjoyned with them) +did affirm, That Figure was not the Cause of the Natation or +Submersion of such Solids as were placed in the water. Nay more, I +cannot omit, but must tell my Antagonists, that this new conceit of +denying that the Superficies of the Board should be bathed, may beget +in a third person an opinion of a poverty of Arguments of defence on +their part, since that such bathing was never insisted upon by them in +the beginning of our Dispute, and was not questioned in the least, +being that the Originall of the discourse arose upon the swiming of +Flakes of Ice, wherein it would be simplicity to require that their +<a name="tnd_38" id="tnd_38"></a><a href="#tn_38" class="tnlink" title="missing space between words">Superficies might bedry:</a> besides, that whether these pieces of Ice be +wet or dry they alwayes swim, and as the Adversaries say, by reason of +the Figure.</p> + +<p>Some peradventure, by way of defence, may say, that wetting the Board +of Ebony, and that in the superiour Superficies, it would, though of +it self unable to pierce and penetrate the water, be born downwards, +if not by the weight of the additionall water, at least by that desire +and propension that the superiour parts of the water have to re-unite +and rejoyn themselves: by the Motion of which parts, the said Board +cometh in a certain manner, to be depressed downwards.</p> + +<div class="sidenote">The Bathed Solid descends not out of any affectation +of union in the upper parts of the water.</div> + +<p>This weak Refuge will be removed, if we do but consider, that the +repugnancy of the inferiour parts of the water, is as great against +Dis-union, as the Inclination of its superiour parts is to union: nor +can the uper unite themselves without depressing the board, nor can it +descend without disuniting the parts of the nether Water: so that it +doth follow, by necessary consequence, that for those respects, it +shall not descend. Moreover, the same that may be said of the upper +parts of the water, may with equall reason be said of the nether, +namely, that desiring to unite, they shall force the said Board +upwards.</p> + +<p>Happily, some of these Gentlemen that dissent from me, will wonder, +that I affirm, that the contiguous superiour Air is able to sustain +that Plate of Brass or of Silver, that stayeth above water; as if I +would in a certain sence allow the Air, a kind of Magnetick vertue of +<span class="sidenote"><i>A</i> Magnetisme in the <i>A</i>ir, by which it bears up +those Solids in the water, that are contiguous with it.</span> +sustaining the grave Bodies, with which it is contiguous. To satisfie +all I may, to all doubts, I have been considering how by some other +sensible Experiment I might demonstrate, how truly that little +contiguous and superiour Air sustaines those Solids, which being by +<span class="pagenum"><a name="Page_39" id="Page_39">[Pg 39]</a></span> +nature apt to descend to the Bottom, being placed lightly on the water +submerge not, unless they be first thorowly bathed; and have found, +that one of these Bodies having descended to the Bottom, by +conveighing to it (without touching it in the least) a little Air, +which conjoyneth with the top of the same, it becometh sufficient, not +only, as before to sustain it, but also to raise it, and to carry it +back to the top, where it stays and abideth in the same manner, till +such time, as the assistance of the conjoyned Air is taken away. And +to this effect, I have taken a Ball of Wax, and made it with a little +Lead, so grave, that it leasurely descends to the Bottom, making with +all its Superficies very smooth and pollite: and this being put gently +into the water, almost wholly submergeth, there remaining vissible +only a little of the very top, the which so long as it is conjoyned +<span class="sidenote">The Effect of the Airs Contiguity in the Natation of +Solids.</span> +with the Air, shall retain the Ball a-top, but the Contiguity of the +Air taken away by wetting it, it shall descend to the Bottom and there +remain. Now to make it by vertue of the Air, that before sustained it +to return again to the top, and stay there, thrust into the water a +Glass reversed with the mouth downwards, the which shall carry with it +the Air it contains, and move this towards the Ball, abasing it till +such time that you see, by the transparency of the Glass, that the +contained Air do arrive to the summity of the <i>B</i>all: then gently +<span class="sidenote">The force of Contact.</span> +withdraw the Glass upwards, and you shall see the <i>B</i>all to rise, and +afterwards stay on the top of the water, if you carefully part the +<span class="sidenote"><i>A</i>n Affectation of Conjunction betwixt Solids and the +Air contiguous to them.</span> +Glass and the water without overmuch commoving and disturbing it. +There is, therefore, a certain affinity between the Air and other +Bodies, <a name="tnd_39" id="tnd_39"></a><a href="#tn_39" class="tnlink" title="missing letter t, unied for united">which holds them unied,</a> so, that they seperate not without a +kind of violence. The same likewise is seen in the water; for if we +<span class="sidenote">The like affectation of Conjunction betwixt Solids & +the water.</span> +shall wholly submerge some Body in it, so that it be thorowly bathed, +in the drawing of it afterwards gently out again, we shall see the +water follow it, and rise notably above its Surface, before it +seperates from it. Solid Bodies, also, if they be equall and alike in +<span class="sidenote">Also the like affectation and Conjunction betwixt +Solids themselves.</span> +Superficies, so, that they make an exact Contact without the +interposition of the least Air, that may part them in the seperation +and yield untill that the ambient <i>Medium</i> succeeds to replenish the +place, do hold very firmly conjoyned, and are not to be seperated +without great force but, because, the Air, Water, and other Liquids, +very expeditiously shape themselves to contact with any Solid +<i>B</i>odies, so that their Superficies do exquisitely adopt themselves to +that of the Solids, without any thing remaining between them, +therefore, the effect of this Conjunction and Adherence is more +manifestly and frequently observed in them, than in hard and +inflexible Bodies, whose Superficies do very rarely conjoyn with +exactness of Contact. This is therefore that Magnetick vertue, which +<span class="sidenote">Contact may be the Cause of the Continuity of Naturall +Bodies.</span> +with firm Connection conjoyneth all Bodies, that do touch without the +interposition of flexible fluids; and, who knows, but that that a +Contact, when it is very exact, may be a sufficient Cause of the Union +and Continuity of the parts of a naturall <i>B</i>ody?</p> +<p><span class="pagenum"><a name="Page_40" id="Page_40">[Pg 40]</a></span></p> + +<p>Now, pursuing my purpose, I say; that it needs not, that we have +recourse to the Tenacity, that the parts of the water have amongst +themselves, by which they resist and oppose Division, Distraction, and +Seperation, because there is no such Coherence and Resistance of +Division for if there were, it would be no less in the internall parts +than in those nearer the superiour or externall Surface, so that the +same Board, finding alwayes the same Resistance and Renitence, would +no less stop in the middle of the water than about the Surface, which +is false. Moreover, what Resistance can we place in the Continuity of +the water, if we see that it is impossible to find any Body of +whatsoever Matter, Figure or Magnitude, which being put into the +water, shall be obstructed and impeded by the Tenacity of the parts of +the water to one another, so, but that it is moved upwards or +downwards, according as the Cause of their Motion transports it? And, +what greater proof of it can we desier, than that which we daily see +in Muddy waters, which being put into Vessels to be drunk, and being, +after some hours setling, still, as we say, thick in the end, after +<span class="sidenote">The settlement of <i>M</i>uddy Water, proveth that that +Element hath no aversion to Division.</span> +four or six dayes they are wholly setled, and become pure and clear? +Nor can their Resistance of Penetration stay those impalpable and +insensible Atomes of Sand, which by reason of their exceeding small +force, spend six dayes in descending the space of half a yard.</p> + +<p><i>Nor let them say, that the seeing of such small Bodies, consume +six dayes in descending so little a way, is a sufficient Argument +of the Waters Resistance of Division; because that is no resisting +of Division, but a retarding of Motion; and it would be simplicity +to say, that a thing opposeth Division, and that in the same +<span class="sidenote">Water cannot oppose division, and at the same time +permit it self to be divided.</span> +instant, it permits it self to be divided: nor doth the Retardation +of Motion at all favour the Adversaries cause, for that they are to +instance in a thing that wholly prohibiteth Motion, and procureth +Rest; it is necessary, therefore, to find out Bodies that stay in +the water, if one would shew its repugnancy to Division, and not +such as move in it, howbeit but slowly.</i></p> + +<p>What then is this Crassitude of the water, with which it resisteth +Division? What, I beseech you, should it be, if we (as we have said +above) with all diligence attempting the reduction of a Matter into so +like a Gravity with the water, that forming it into a dilated Plate it +rests suspended as we have said, between the two waters, it be +impossible to effect it, though we bring them to such an +Equiponderance, that as much Lead as the fourth part of a Grain of +Musterd-seed, added to the same expanded Plate, that in Air [<i>i. e. +out of the water</i>] shall weigh four or six pounds, sinketh it to the +Bottom, and being substracted, it ascends to the Surface of the water? +I cannot see, (if what I say be true, as it is most certain) what +minute vertue and force we can possibly find or imagine, to which the +Resistance of the water against Division and Penetration is not +<span class="pagenum"><a name="Page_41" id="Page_41">[Pg 41]</a></span> +inferiour; whereupon, we must of necessity conclude that it is +nothing: because, if it were of any sensible power, some large Plate +might be found or compounded of a Matter alike in Gravity to the +water, which not only would stay between the two waters; but, +moreover, should not be able to descend or ascend without notable +force. We may likewise collect the same from an other Experiment, +<span class="sidenote">An hair will draw a great Mass thorow the Water; which +proveth, that it hath no Resistance against transversall +Division.</span> +shewing that the Water gives way also in the same manner to +transversall Division; for if in a setled and standing water we should +place any great Mass that goeth not to the bottom, drawing it with a +single Womans Hair, we might carry it from place to place without any +opposition, and this whatever Figure it hath, though that it possess a +great space of water, as for instance, a great Beam would do moved +side-ways. Perhaps some might oppose me and say, that if the +Resistance of water against Division, as I affirm, were nothing; Ships +should not need such a force of Oars and Sayles for the moving of them +from place to place in a tranquile Sea, or standing Lake. To him that +should make such an objection, I would reply, that the water +<span class="sidenote">How ships are moved in the water.</span> +contrasteth not against, nor simply resisteth Division, but a sudden +Division, and with so much greater Renitence, by how much greater the +Velocity is: and the Cause of this Resistance depends not on +Crassitude, or any other thing that absolutely opposeth Division, but +because that the parts of the water divided, in giving way to that +Solid that is moved in it, are themselves also necessitated locally to +move, some to the one side, and some to the other, and some downwards: +and this must no less be done by the waves before the Ship, or other +Body swimming through the water, than by the posteriour and +subsequent; because, the Ship proceeding forwards, to make it self a +way to receive its Bulk, it is requisite, that with the Prow it +repulse the adjacent parts of the water, as well on one hand as on the +other, and that it move them as much transversly, as is the half of +the breadth of the Hull: and the like removall must those waves make, +that succeeding the Poump do run from the remoter parts of the Ship +towards those of the middle, successively to replenish the places, +which the Ship in advancing forwards, goeth, leaving vacant. Now, +because, <a name="tnd_41" id="tnd_41"></a><a href="#tn_41" class="tnlink" title="printer's error, Motitions for Motions">all Motitions are made</a> in Time, and the longer in greater +<span class="sidenote">Bodies moved a certain space in a certain Time, by a +certain power, cannot be moved the same space and in a shorter +time, but by a greater power.</span> +time: and it being moreover true, that those Bodies that in a certain +time are moved by a certain power such a certain space, shall not be +moved the same space, and in a shorter Time, unless by a greater +Power: therefore, the broader Ships move slower than the narrower, +being put on by an equall Force: and the same Vessel requires so much +greater force of Wind, or Oars, the faster it is to move.</p> +<p><span class="pagenum"><a name="Page_42" id="Page_42">[Pg 42]</a></span></p> + +<p><i>But yet for all this, any great Mass swimming in a standing Lake, +may be moved by any petit force; only it is true, that a lesser +force more slowly moves it: but if the waters Resistance of +Division, were in any manner sensible, it would follow, that the +said Mass, should, notwithstanding the percussion of some sensible +force, continue immoveable, which is not so. Yea, I will say +<span class="sidenote">The parts of Liquids, so farre from resisting +Division, that they contain not any thing that may be divided.</span> +farther, that should we retire our selves into the more internall +contemplation of the Nature of water and other Fluids, perhaps we +should discover the Constitution of their parts to be such, that +they not only do not oppose Division, but that they have not any +thing in them to be divided: so that the Resistance that is +observed in moving through the water, is like to that which we meet +<span class="sidenote">The Resistance a Solid findeth in moving through the +water, like to that we meet with in passing through a throng of +people:</span> +with in passing through a great Throng of People, wherein we find +impediment, and not by any difficulty in the Division, for that +none of those persons are divided whereof the Croud is composed, +but only in moving of those persons side-ways which were before +divided and disjoyned: and thus we find Resistance in thrusting a +Stick into an heap of Sand, not because any part of the Sand is to +be cut in pieces, but only to be moved and raised. Two manners of +<span class="sidenote">Or in thrusting a Stick into an heap of Sand.</span> +Penetration, therefore, offer themselves to us, one in Bodies, +whose parts were continuall, and here Division seemeth necessary, +the other in the aggregates of parts not continuall, but contiguous +only, and here there is no necessity of dividing but of moving +<span class="sidenote">Two kinds of Penetration, one in Bodies continuall, the +other in Bodies only contiguous.</span> +only. Now, I am not well resolved, whether water and other Fluids +may be esteemed to be of parts continuall or contiguous only; yet I +<span class="sidenote">Water consists not of continuall, but only of +contiguous parts.</span> +find my self indeed inclined to think that they are rather +contiguous (if there be in Nature no other manner of aggregating, +than by the union, or by the touching of the extreams:) and I am +induced thereto by the great difference that I see between the +Conjunction of the parts of an hard or Solid Body, and the +<span class="sidenote"><i><a name="tnd_42" id="tnd_42"></a><a href="#tn_42" class="tnlink" title="possible missing letter e">Se{e} what satisfaction</a> he hath given, as to this +point, in Lib. de Motu. Dial. 2.</i></span> +Conjunction of the same parts when the same Body shall be made +Liquid and Fluid: for if, for example, I take a Mass of Silver or +other Solid and hard Mettall, I shall in dividing it into two +parts, find not only the resistance that is found in the moving of +it only, but an other incomparably greater, dependent on that +<span class="sidenote">Great difference betwixt the Conjunction of the parts +of a Body when Solid, and when fluid.</span> +vertue, whatever it be, which holds the parts united: and so if we +would divide again those two parts into other two, and successively +into others and others, we should still find a like Resistance, but +ever less by how much smaller the parts to be divided shall be; but +if, lastly, employing most subtile and acute Instruments, such as +are the most tenuous parts of the Fire, we shall resolve it +(perhaps) into its last and least Particles, there shall not be +left in them any longer either Resistance of Division, or so much +as a capacity of being farther divided, especially by Instruments +more grosse than the acuities of Fire: and what Knife or Rasor put +into well melted Silver can we finde, that will divide a thing +which surpasseth the separating power of Fire? Certainly none: +because either the whole shall be reduced to the most minute and +ultimate Divisions, or if there remain parts capable still of other +<span class="pagenum"><a name="Page_43" id="Page_43">[Pg 43]</a></span> +<a name="tnd_43" id="tnd_43"></a><a href="#tn_43" class="tnlink" title="printer's error, Subdidivisions for Subdivisions">Subdidivisions,</a> they cannot receive them, but only from acuter +Divisors than Fire; but a Stick or Rod of Iron, moved in the melted +Metall, is not such a one. Of a like Constitution and Consistence, +I account the parts of Water, and other Liquids to be, namely, +<span class="sidenote">Water consists of parts that admit of no farther +division.</span> +incapable of Division by reason of their Ienuity; or if not +absolutely indivisible, yet at least not to be divided by a Board, +or other Solid Body, palpable unto the hand, the Sector being +alwayes required to be more sharp than the Solid to be cut. Solid +Bodies, therefore, do only move, and not divide the Water, when put +<span class="sidenote">Solids dimitted into the water, do onely move, and not +divide it.</span> +into it; whose parts being before divided to the extreamest +minuity, and therefore capable of being moved, either many of them +at once, or few, or very few, they soon give place to every small +Corpuscle, that descends in the same: for that, it being little and +light, descending in the Air, and arriving to the Surface of the +Water, it meets with Particles of Water more small, and of less +Resistance against Motion and Extrusion, than is its own prement +and extrusive force; whereupon it submergeth, and moveth such a +portion of them, as is proportionate to its Power. There is not, +therefore, any Resistance in Water against Division, nay, there is +not in it any divisible parts. I adde; moreover, that in case yet +there should be any small Resistance found (which is absolutely +false) haply in attempting with an Hair to move a very great natant +<span class="sidenote">If there were any Resistance of Division in water, it +must needs be small, in that it is overcome by an Hair, a Grain of +Lead, or a slight bathing of the Solid.</span> +Machine, or in essaying by the addition of one small Grain of Lead +to sink, or by removall of it to raise a very broad Plate of +Matter, equall in Gravity with Water, (which likewise will not +happen, in case we proceed with dexterity) we may observe that that +Resistance is a very different thing from that which the +Adversaries produce for the Cause of the Natation of the Plate of +Lead or Board of Ebony, for that one may make a Board of Ebony, +which being put upon the Water swimmeth, and cannot be submerged, +no not by the addition of an hundred Grains of Lead put upon the +same, and afterwards being bathed, not only sinks, though the said +Lead be taken away, but though moreover a quantity of Cork, or of +some other light Body fastened to it, sufficeth not to hinder it +from sinking unto the bottome: so that you see, that although it +were granted that there is a certain small Resistance of Division +found in the substance of the Water, yet this hath nothing to do +with that Cause which supports the Board above the Water, with a +Resistance an hundred times greater than that which men can find in +the parts of the Water: nor let them tell me, that only the Surface +of the Water hath such Resistance, and not the internall parts, or +<span class="sidenote">The uper parts of the Water, do no more resist Division +than the middle or lower parts.</span> +that such Resistance is found greatest in the beginning of the +Submersion, as it also seems that in the beginning, Motion meets +with greater opposition, than in the continuance of it; because, +first, I will permit, that the Water be stirred, and that the +superiour parts be mingled with the middle, and inferiour parts, or +<span class="sidenote">Waters Resistance of division, not greater in the +beginning of the Submersion.</span> +that those above be wholly removed, and those in the middle only +made use off, and yet you shall see the effect for all that, to be +<span class="pagenum"><a name="Page_44" id="Page_44">[Pg 44]</a></span> +still the same: Moreover, that Hair which draws a Beam through the +Water, is likewise to divide the upperparts, and is also to begin +the Motion, and yet it begins it, and yet it divides it: and +finally, let the Board of Ebony be put in the midway, betwixt the +bottome and the top of the Water, and let it there for awhile be +suspended and setled, and afterwards let it be left at liberty, and +it will instantly begin its Motion, and will continue it unto the +bottome. Nay, more, the Board so soon as it is dimitted upon the +Water, hath not only begun to move and divide it, but is for a good +space dimerged into it.</i></p> + +<p>Let us receive it, therefore, for a true and undoubted Conclusion, +That the Water hath not any Renitence against simple Division, and +that it is not possible to find any Solid Body, be it of what Figure +it will, which being put into the Water, its Motion upwards or +downwards, according as it exceedeth, or shall be exceeded by the +Water in Gravity (although such excesse and difference be insensible) +shall be prohibited, and taken away, by the Crassitude of the said +Water. When, therefore, we see the Board of Ebony, or of other Matter, +more grave than the Water, to stay in the Confines of the Water and +Air, without submerging, we must have recourse to some other +Originall, for the investing the Cause of that Effect, than to the +breadth of the Figure, unable to overcome the Renitence with which the +Water opposeth Division, since there is no Resistance; and from that +which is not in being, we can expect no Action. It remains most true, +therefore, as we have said before, that this so succeds, for that that +which in such manner put upon the water, not the same Body with that +which is put <i>into</i> the Water: because this which is put <i>into</i> the +Water, is the pure Board of Ebony, which for that it is more grave +than the Water, sinketh, and that which is put <i>upon</i> the Water, is a +Composition of Ebony, and of so much Air, that both together are +specifically less grave than the Water, and therefore they do not +descend.</p> + +<p>I will farther confirm this which I say. Gentlemen, my Antagonists, we +are agreed, that the excess or defect of the Gravity of the Solid, +unto the Gravity of the Water, is the true and proper Cause of +Natation or Submersion.</p> + +<div class="sidenote">Great Caution to be had in experimenting the operation +of Figure in Natation.</div> + +<p>Now, if you will shew that besides the former Cause, there is another +which is so powerfull, that it can hinder and remove the Submersion of +those very Solids, that by their Gravity sink, and if you will say, +that this is the breadth or ampleness of Figure, you are oblieged, +when ever you would shew such an Experiment, first to make the +circumstances certain, that that Solid which you put into the Water, +be not less grave <i>in specie</i> than it, for if you should not do so, +any one might with reason say, that not the Figure, but the Levity was +the cause of that Natation. But I say, that when you shall dimit a +<span class="pagenum"><a name="Page_45" id="Page_45">[Pg 45]</a></span> +Board of Ebony into the Water, you do not put therein a Solid more +grave <i>in specie</i> than the Water, but one lighter, for besides the +Ebony, there is in the Water a Mass of Air, united with the Ebony, and +such, and so light, that of both there results a Composition less +grave than the Water: See, therefore, that you remove the Air, and put +the Ebony alone into the Water, for so you shall immerge a Solid more +grave then the Water, and if this shall not go to the Bottom, you have +well Philosophized and I ill.</p> + +<p>Now, since we have found the true Cause of the Natation of those +Bodies, which otherwise, as being graver than the Water, would descend +to the bottom, I think, that for the perfect and distinct knowledge of +this business, it would be good to proceed in a way of discovering +demonstratively those particular Accidents that do attend these +effects, and,</p> + + + +<h2><a name="PROBL_I" id="PROBL_I"></a>PROBL. I.</h2> + +<div class="sidenote">To finde the proportion Figures ought to have to the +waters Gravity, that by help of the contiguous Air, they may +swim.</div> + +<p class="def_head"><i>To finde what proportion severall Figures of different Matters +ought to have, unto the Gravity of the Water, that so they may be +able by vertue of the Contiguous Air to stay afloat.</i></p> + + +<p class="cap">Let, therefore, for better illustration, D F N E be a Vessell, +wherein the water is contained, and suppose a Plate or Board, whose +thickness is comprehended between the Lines I C and O S, and let it be +of Matter exceeding the water in Gravity, so that being put upon the +water, it dimergeth and abaseth below the Levell of the said water, +leaving the little Banks A I and B C, which are at the greatest height +they can be, so that if the Plate I S should but descend any little +space farther, the little Banks or Ramparts would no longer consist, +<span class="figright" style="width: 195px;"> +<img src="images/i047.png" width="195" height="77" alt="" title="" /> +</span> +but expulsing the Air A I C B, they would diffuse themselves over the +Superficies I C, and would submerge the Plate. The height A I B C is +therefore the greatest profundity that the little Banks of water admit +of. Now I say, that from this, and from the proportion in Gravity, +that the Matter of the Plate hath to the water, we may easily finde of +what thickness, at most, we may make the said Plates, to the end, they +may be able to bear up above water: for if the Matter of the Plate or +Board I S were, for Example, as heavy again as the water, a Board of +that Matter shall be, at the most of a thickness equall to the +greatest height of the Banks, that is, as thick as A I is high: which +we will thus demonstrate. Let the Solid I S be double in Gravity to +the water, and let it be a regular Prisme, or Cylinder, to wit, that +<span class="pagenum"><a name="Page_46" id="Page_46">[Pg 46]</a></span> +hath its two flat Superficies, superiour and inferiour, alike and +equall, and at Right Angles with the other laterall Superficies, and +let its thickness I O be equall to the greatest Altitude of the Banks +<span class="figleft" style="width: 198px;"> +<img src="images/i048.png" width="198" height="81" alt="" title="" /> +</span> +of water: I say, that if it be put upon the water, it will not +submerge: for the Altitude A I being equall to the Altitude I O, the +Mass of the Air A B C I shall be equall to the Mass of the Solid C I O +S: and the whole Mass A O S B double to the Mass I S; And since the +Mass of the Air A C, neither encreaseth nor diminisheth the Gravity of +the Mass I S, and the Solid I S was supposed double in Gravity to the +water; Therefore as much water as the Mass submerged A O S B, +compounded of the Air A I C B, and of the Solid I O S C, weighs just +as much as the same submerged Mass A O S B: but when such a Mass of +water, as is the submerged part of the Solid, weighs as much as the +said Solid, it descends not farther, but resteth, as by (<i>a</i>) +<i>Archimedes</i>, and above by us, hath been demonstrated: Therefore, I S +<span class="sidenote">Of Natation Lib. 1. Prop. 3.</span> +shall descend no farther, but shall rest. And if the Solid I S shall +be Sesquialter in Gravity to the water, it shall float, as long as its +thickness be not above twice as much as the greatest Altitude of the +Ramparts of water, that is, of A I. For I S being Sesquialter in +Gravity to the water, and the Altitude O I, being double to I A, the +Solid submerged A O S B, shall be also Sesquialter in Mass to the +Solid I S. And because the Air A C, neither increaseth nor diminisheth +the ponderosity of the Solid I S: Therefore, as much water in quantity +as the submerged Mass A O S B, weighs as much as the said Mass +submerged: And, therefore, that Mass shall rest. And briefly in +generall.</p> + + + + +<h2><a name="THEOREME_VI" id="THEOREME_VI"></a>THEOREME. VI.</h2> + +<div class="sidenote">The proportion of the greatest thickness of Solids, +beyond which encreased they sink.</div> + +<p class="def_head"><i>When ever the excess of the Gravity of the Solid above the Gravity +of the Water, shall have the same proportion to the Gravity of +the Water, that the Altitude of the Rampart, hath to the +thickness of the Solid, that Solid shall not sink, but being +never so little thicker it shall.</i></p> + + +<p class="cap">Let the Solid I S be superior in Gravity to the water, and of such +thickness, that the Altitude of the Rampart A I, be in proportion to +the thickness of the Solid I O, as the excess of the Gravity of the +said Solid I S, above the Gravity of a Mass of water equall to the +Mass I S, is to the Gravity of the Mass of water equall to the Mass I +<span class="pagenum"><a name="Page_47" id="Page_47">[Pg 47]</a></span> +<span class="figright" style="width: 196px;"> +<img src="images/i049.png" width="196" height="80" alt="" title="" /> +</span> +S. I say, that the Solid I S shall not sinke, but being never so +little thicker it shall go to the bottom: For being that as A I is to +I O, so is the Excess of the Gravity of the Solid I S, above the +Gravity of a Mass of water equall to the Mass I S, to the Gravity of +the said Mass of water: Therefore, compounding, as A O is to O I, so +shall the Gravity of the Solid I S, be to the Gravity of a Mass of +water equall to the Mass I S: And, converting, as I O is to O A, so +shall the Gravity of a Mass of water equall to the Mass I S, be to the +Gravity of the Solid I S: But as I O is to O A, so is a Mass of water +I S, to a Mass of water equall to the Mass A B S O: and so is the +Gravity of a Mass of water I S, to the Gravity of a Mass of water A S: +Therefore as the Gravity of a Mass of water, equall to the Mass I S, +is to the Gravity of the Solid I S, so is the same Gravity of a Mass +of water I S, to the Gravity of a Mass of Water A S: Therefore the +Gravity of the Solid I S, is equall to the Gravity of a Mass of water +equall to the Mass A S: But the Gravity of the Solid I S, is the same +with the Gravity of the Solid A S, compounded of the Solid I S, and of +the Air A B C I. Therefore the whole compounded Solid A O S B, weighs +as much as the water that would be comprised in the place of the said +Compound A O S B: And, therefore, it shall make an <i>Equilibrium</i> and +rest, and that same Solid I O S C shall sinke no farther. But if its +thickness I O should be increased, it would be necessary also to +encrease the Altitude of the Rampart A I, to maintain the due +proportion: But by what hath been supposed, the Altitude of the +Rampart A I, is the greatest that the Nature of the Water and Air do +admit, without the waters repulsing the Air adherent to the +Superficies of the Solid I C, and possessing the space A I C B: +Therefore, a Solid of greater thickness than I O, and of the same +Matter with the Solid I S, shall not rest without submerging, but +shall descend to the bottome: which was to be demonstrated. In +consequence of this that hath been demonstrated, sundry and various +Conclusions may be gathered, by which the truth of my principall +Proposition comes to be more and more confirmed, and the imperfection +of all former Argumentations touching the present Question cometh to +be discovered.</p> + +<p><i>And first we gather from the things demonstrated, that,</i></p> +<p><span class="pagenum"><a name="Page_48" id="Page_48">[Pg 48]</a></span></p> + + +<h2><a name="THEOREME_VII" id="THEOREME_VII"></a>THEOREME VII.</h2> + +<div class="sidenote">The heaviest Bodies may swimme.</div> + +<p class="def_head"><i>All Matters, how heavy soever, even to Gold it self, the heaviest +of all Bodies, known by us, may float upon the Water.</i></p> + + +<p class="cap">Because its Gravity being considered to be almost twenty times greater +than that of the water, and, moreover, the greatest Altitude that the +Rampart of water can be extended to, without breaking the Contiguity +of the Air, adherent to the Surface of the Solid, that is put upon the +water being predetermined, if we should make a Plate of Gold so thin, +that it exceeds not the nineteenth part of the Altitude of the said +Rampart, this put lightly upon the water shall rest, without going to +the bottom: and if Ebony shall chance to be in sesquiseptimall +proportion more grave than the water, the greatest thickness that can +be allowed to a Board of Ebony, so that it may be able to stay above +water without sinking, would be seaven times more than the height of +the Rampart Tinn, <i>v. gr.</i> eight times more grave than water, shall +swimm as oft as the thickness of its Plate, exceeds not the 7th part +of the Altitude of the Rampart.</p> + +<div class="sidenote"><i>He elsewhere cites this as a Proposition, therefore I +make it of that number.</i></div> + +<p>And here I will not omit to note, as a second Corrollary dependent +upon the things demonstrated, that,</p> + + + +<h2><a name="THEOREME_VIII" id="THEOREME_VIII"></a>THEOREME VIII.</h2> + +<div class="sidenote">Natation and Submersion, collected from the thickness, +excluding the length and breadth of Plates.</div> + +<p class="def_head"><i>The Expansion of Figure not only is not the Cause of the Natation +of those grave Bodies, which otherwise do submerge, but also the +determining what be those Boards of Ebony, or Plates of Iron or +Gold that will swimme, depends not on it, rather that same +determination is to be collected from the only thickness of those +Figures of Ebony or Gold, wholly excluding the consideration of +length and breadth, as having no wayes any share in this Effect.</i></p> + + +<p class="cap">It hath already been manifested, that the only cause of the Natation +of the said Plates, is the reduction of them to be less grave than the +water, by means of the connexion of that Air, which descendeth +together with them, and possesseth place in the water; which place so +occupyed, if before the circumfused water diffuseth it self to fill +it, it be capable of as much water, as shall weigh equall with the +Plate, the Plate shall remain suspended, and sinke no farther.</p> +<p><span class="pagenum"><a name="Page_49" id="Page_49">[Pg 49]</a></span></p> + +<p>Now let us see on which of these three dimensions of the Solid +depends the terminating, what and how much the Mass of that ought to +be, that so the assistance of the Air contiguous unto it, may suffice +to render it specifically less grave than the water, whereupon it may +rest without Submersion. It shall undoubtedly be found, that the +length and breadth have not any thing to do in the said determination, +but only the height, or if you will the thickness: for, if we take a +Plate or Board, as for Example, of Ebony, whose Altitude hath unto the +greatest possible Altitude of the Rampart, the proportion above +declared, for which cause it swims indeed, but yet not if we never so +little increase its thickness; I say, that retaining its thickness, +and encreasing its Superficies to twice, four times, or ten times its +bigness, <a name="tnd_49" id="tnd_49"></a><a href="#tn_49" class="tnlink" title="missing letter i, dminishing for diminishing">or dminishing it by dividing</a> it into four, or six, or twenty, +or a hundred parts, it shall still in the same manner continue to +float: but encreasing its thickness only a Hairs breadth, it will +alwaies submerge, although we should multiply the Superficies a +hundred and a hundred times. Now forasmuch as that this is a Cause, +which being added, we adde also the Effect, and being removed, it is +removed; and by augmenting or lessening the length or breadth in any +manner, the effect of going, or not going to the bottom, is not added +or removed: I conclude, that the greatness and smalness of the +Superficies hath no influence upon the Natation or Submersion. And +that the proportion of the Altitude of the Ramparts of Water, to the +Altitude of the Solid, being constituted in the manner aforesaid, the +greatness or smalness of the Superficies, makes not any variation, is +manifest from that which hath been above demonstrated, and from this, +that, <i>The Prisms and Cylinders which have the same Base, are in +proportion to one another as their heights.</i> Whence Cylinders or +Prismes, namely, the Board, be they great or little, so that they be +<span class="sidenote">Prismes and Cylinders having the same Base, are to one +another as their heights.</span> +all of equall thickness, have the same proportion to their +Conterminall Air, which hath for Base the said Superficies of the +Board, and for height the Ramparts of water; so that alwayes of that +Air, and of the Board, Solids, are compounded, that in Gravity equall +a Mass of water equall to the Mass of the Solids, compounded of Air, +and of the Board: whereupon all the said Solids do in the same manner +continue afloat. We will conclude in the third place, that,</p> +<p><span class="pagenum"><a name="Page_50" id="Page_50">[Pg 50]</a></span></p> + + + +<h2><a name="THEOREME_IX" id="THEOREME_IX"></a>THEOREME. IX.</h2> + +<div class="sidenote">All Figures of all Matters, <a name="tnd_50" id="tnd_50"></a><a href="#tn_50" class="tnlink" title="printer's error, missing letter l, hep for help">float by hep of</a> the +Rampart replenished with Air, and some but only touch the water.</div> + +<p class="def_head"><i>All sorts of Figures of whatsoever Matter, albeit more grave than +the Water, do by Benefit of the said Rampart, not only float, but +some Figures, though of the gravest Matter, do stay wholly above +Water, wetting only the inferiour Surface that toucheth the +Water.</i></p> + + +<p class="cap">And these shall be all Figures, which from the inferiour Base upwards, +grow lesser and lesser; the which we shall exemplifie for this time in +Piramides or Cones, of which Figures the passions are common. We will +demonstrate therefore, that,</p> + +<p><i>It is possible to form a Piramide, of any whatsoever Matter +preposed, which being put with its Base upon the Water, rests not +only without submerging, but without wetting it more then its +Base.</i></p> + +<p>For the explication of which it is requisite, that we first +demonstrate the subsequent Lemma, namely, that,</p> + + + + +<h2><a name="LEMMA_II" id="LEMMA_II"></a>LEMMA II.</h2> + +<div class="sidenote">Solids whose Masses are in contrary proportion to +their Specifick Gravities are equall in absolute Gravity.</div> + +<p class="def_head"><i>Solids whose Masses answer in proportion contrarily to their +Specificall Gravities, are equall in Absolute Gravities.</i></p> + + +<p class="cap">Let A C and B be two Solids, and let the Mass A C be to the Mass B, +as the Specificall Gravity of the Solid B, is to the Specificall +Gravity of the Solid A C: I say, the Solids A C and B are equall in +<span class="figleft" style="width: 156px;"> +<img src="images/i052.png" width="156" height="103" alt="" title="" /> +</span> +absolute weight, that is, equally grave. For if the Mass A C be equall +to the Mass B, then, by the Assumption, the Specificall Gravity of B, +shall be equall to the Specificall Gravity of A C, and being equall in +Mass, and of the same Specificall Gravity they shall absolutely weigh +one as much as another. But if their Masses shall be unequall, let the +Mass A C be greater, and in it take the part C, equall to the Mass B. +And, because the Masses B and C are equall; the Absolute weight of B, +shall have the same proportion to the Absolute weight of C, that the +Specificall Gravity of B, hath to the Specificall Gravity of C; or of +C A, which is the same <i>in specie</i>: But look what proportion the +Specificall Gravity of B, hath to the Specificall Gravity of C A, the +like proportion, by the Assumption, hath the Mass C A, to the Mass B, +<span class="pagenum"><a name="Page_51" id="Page_51">[Pg 51]</a></span> +that is, to the Mass C: Therefore, the absolute weight of B, to the +absolute weight of C, is as the Mass A C to the Mass C: But as the +Mass A C, is to the Mass C, so is the absolute weight of A C, to the +absolute weight of C: Therefore the absolute weight of B, hath the +same proportion to the absolute weight of C, that the absolute weight +of A C, hath to the absolute weight of C: Therefore, the two Solids A +C and B are equall in absolute Gravity: which was to be demonstrated. +Having demonstrated this, I say,</p> + + + + +<h2><a name="THEOREME_X" id="THEOREME_X"></a>THEOREME X.</h2> + +<div class="sidenote">There may be Cones and Piramides of any Matter, which +demitted into the water, rest only their Bases.</div> + +<p class="def_head"><i>That it is possible of any assigned Matter, to form a Piramide or +Cone upon any Base, which being put upon the Water shall not +submerge, nor wet any more than its Base.</i></p> + + +<p class="cap">Let the greatest possible Altitude of the Rampart be the Line D B, +and the Diameter of the Base of the Cone to be made of any Matter +assigned B C, at right angles to D B: And as the Specificall Gravity +<span class="figright" style="width: 173px;"> +<img src="images/i053.png" width="173" height="213" alt="" title="" /> +</span> +of the Matter of the Piramide or Cone to be made, is to the +Specificall Gravity of the water, so let the Altitude of the Rampart D +B, be to the third part of the Piramide or Cone A B C, described upon +the Base, whose Diameter is B C: I say, that the said Cone A B C, and +any other Cone, lower then the same, shall rest upon the Surface of +the water B C without sinking. Draw D F parallel to B C, and suppose +the Prisme or Cylinder E C, which shall be tripple to the Cone A B C. +And, because the Cylinder D C hath the same proportion to the Cylinder +C E, that the Altitude D B, hath to the Altitude B E: But the Cylinder +C E, is to the Cone A B C, as the Altitude E B is to the third part of +the Altitude of the Cone: Therefore, by Equality of proportion, the +Cylinder D C is to the Cone A B C, as D B is to the third part of the +Altitude B E: But as D B is to the third part of B E, so is the +Specificall Gravity of the Cone A B C, to the Specificall Gravity of +the water: Therefore, as the Mass of the Solid D C, is to the Mass of +the Cone A <i>B</i> C, so is the Specificall Gravity of the said Cone, to +the Specificall Gravity of the water: Therefore, by the precedent +Lemma, the Cone A B C weighs in absolute Gravity, as much as a Mass of +Water equall to the Mass D C: But the water which by the imposition of +the Cone A B C, is driven out of its place, is as much as would +precisely lie in the place D C, and is equall in weight to the Cone +that displaceth it: Therefore, there shall be an <i>Equilibrium</i>, and +the Cone shall rest without farther submerging. And its manifest,</p> +<p><span class="pagenum"><a name="Page_52" id="Page_52">[Pg 52]</a></span></p> + +<h3>COROLARY I.</h3> + +<div class="sidenote">Amongst Cones of the same Base, those of least +Altitude shall sink the least.</div> + +<p class="cor_head"><i>That making upon the same Basis, a Cone of a less Altitude, it +shall be also less grave, and shall so much the more rest without +Submersion.</i></p> + + +<h3>COROLARY II.</h3> + +<div class="sidenote">There may be Cones and Piramides of any Matter, which +demitted with the Point downwards do float atop.</div> + +<p class="cor_head"><i>It is manifest, also, that one may make Cones and Piramids of any +Matter whatsoever, more grave than the water, which being put +into the water, with the Apix or Point downwards, rest without +Submersion.</i></p> + +<p class="cap">Because if we reassume what hath been above demonstrated, of Prisms +and Cylinders, and that on Bases equall to those of the said +Cylinders, we make Cones of the same Matter, and three times as high +as the Cylinders, they shall rest afloat, for that in Mass and Gravity +they shall be equall to those Cylinders, and by having their Bases +equall to those of the Cylinders, they shall leave equall Masses of +Air included within the Ramparts. This, which for Example sake hath +been demonstrated, in Prisms, Cylinders, Cones and Piramids, might be +proved in all other Solid Figures, but it would require a whole Volume +(such is the multitude and variety of their Symptoms and Accidents) to +comprehend the particuler demonstration of them all, and of their +severall Segments: but I will to avoid prolixity in the present +Discourse, content my self, that by what I have declared every one of +ordinary Capacity may comprehend, that there is not any Matter so +grave, no not Gold it self, of which one may not form all sorts of +Figures, which by vertue of the superiour Air adherent to them, and +not by the Waters Resistance of Penetration, do remain afloat, so that +they sink not. Nay, farther, I will shew, for removing that Error, +that,</p> + + + + +<h2><a name="THEOREME_XI" id="THEOREME_XI"></a>THEOREME XI.</h2> + +<div class="sidenote">A Piramide or Cone, demitted with the Point downwards +shal swim, with its Base downward shall sink.</div> + +<p class="def_head"><i>A Piramide or Cone put into the Water, with the Point downward +shall swimme, and the same put with the Base downwards shall +sinke, and it shall be impossible to make it float.</i></p> + + +<p class="cap">Now the quite contrary would happen, if the difficulty of Penetrating +the water, were that which had hindred the descent, for that the said +Cone is far apter to pierce and penetrate with its sharp Point, than +with its broad and spacious Base.</p> + +<p>And, to demonstrate this, let the Cone be <i>A B C</i>, twice as grave as +the water, and let its height be tripple to the height of the Rampart +<i>D A E C</i>: I say, first, that being put lightly into the water with +<span class="pagenum"><a name="Page_53" id="Page_53">[Pg 53]</a></span> +<span class="figright" style="width: 173px;"> +<img src="images/i055a.png" width="173" height="98" alt="" title="" /> +</span> +the Point downwards, it shall not descend to the bottom: for the +Aeriall Cylinder contained betwixt the Ramparts <i>D A C E</i>, is equall +in Mass to the Cone <i>A B C</i>; so that the whole Mass of the Solid +compounded of the Air <i>D A C E</i>, and of the Cone <i>A B C</i>, shall be +double to the Cone <i>A C B</i>: And, because the Cone <i>A B C</i> is supposed +to be of Matter double in Gravity to the water, therefore as much +water as the whole Masse <i>D A B C E</i>, placed beneath the Levell of the +water, weighs as much as the Cone <i>A B C</i>: and, therefore, there shall +be an <i>Equilibrium</i>, and the Cone <i>A B C</i> shall descend no lower. Now, +I say farther, that the same Cone placed with the Base downwards, +shall sink to the bottom, without any possibility of returning again, +by any means to swimme.</p> + +<p>Let, therefore, the Cone be <i>A B D</i>, double in Gravity to the water, +<span class="figright" style="width: 164px;"> +<img src="images/i055b.png" width="164" height="203" alt="" title="" /> +</span> +and let its height be tripple the height of the Rampart of water L B: +It is already manifest, that it shall not stay wholly out of the +water, because the Cylinder being comprehended betwixt the Ramparts <i>L +B D P</i>, equall to the Cone <i>A B D</i>, and the Matter of the Cone, <a name="tnd_53" id="tnd_53"></a><a href="#tn_53" class="tnlink" title="printer's error, missing letter n, beig for being">beig +double in Gravity</a> to the water, it is evident that the weight of the +said Cone shall be double to the weight of the Mass of water equall to +the Cylinder <i>L B D P</i>: Therefore it shall not rest in this state, but +shall descend.</p> + + +<h3>COROLARY I.</h3> + +<div class="sidenote">Much less shall the said Cone swim, if one immerge a +part thereof.</div> + +<p class="cor_head"><i>I say farther; that much lesse shall the said Cone stay afloat, if +one immerge a part thereof.</i></p> + +<p class="cap">Which you may see, comparing with the water as well the part that +shall immerge as the other above water. Let us therefore of the Cone A +B D, submergeth part N T O S, and advance the Point N S F above water. +The Altitude of the Cone F N S, shall either be more than half the +whole Altitude of the Cone F T O, or it shall not be more: if it shall +be more than half, the Cone F N S shall be more than half of the +Cylinder E N S C: for the Altitude of the Cone F N S, shall be more +than Sesquialter of the Altitude of the Cylinder E N S C: And, because +the Matter of the Cone is supposed to be double in Specificall Gravity +to the water, the water which would be contained within the Rampart E +N S C, would be less grave absolutely than the Cone F N S; so that the +whole Cone F N S cannot be sustained by the Rampart: But the part +immerged N T O S, by being double in Specificall Gravity to the water, +shall tend to the bottom: Therefore, the whole <i>C</i>one F T O, as well +in respect of the part submerged, as the part above water shall +<span class="pagenum"><a name="Page_54" id="Page_54">[Pg 54]</a></span> +descend to the bottom. But if the Altitude of the Point F N S, shall +be half the Altitude of the whole Cone F T O, the same Altitude of the +said Cone F N S shall be Sesquialter to the Altitude E N: and, +therefore, E N S C shall be double to the Cone F N S; and as much +water in Mass as the <i>C</i>ylinder E N S C, would weigh as much as the +part of the <i>C</i>one F N S. But, because the other immerged part N T O +S, is double in Gravity to the water, a Mass of water equall to that +compounded of the <i>C</i>ylinder E N S C, and of the Solid N T O S, shall +weigh less than the <i>C</i>one F T O, by as much as the weight of a Mass +of water equall to the Solid N T O S: Therefore, the <i>C</i>one <a name="tnd_54" id="tnd_54"></a><a href="#tn_54" class="tnlink" title="printer's error, missing letter l">sha{l}l +also descend.</a> Again, because the Solid N T O S, is septuple to the +Cone F N S, to which the <i>C</i>ylinder E S is double, the proportion of +the Solid N T O S, shall be to the <i>C</i>ylinder E N S C, as seaven to +two: Therefore, the whole Solid compounded of the <i>C</i>ylinder E N S C, +and of the Solid N T O S, is much less than double the Solid N T O S: +Therefore, the single Solid N T O S, is much graver than a Mass of +water equall to the Mass, compounded of the <i>C</i>ylinder E N S C, and of +N T O S.</p> + + +<h3>COROLARY II.</h3> + +<div class="sidenote">Part of the Cones towards the Cuspis removed, it shall +still sink.</div> + +<p class="cor_head"><i>From whence it followeth, that though one should remove and take +away the part of the Cone F N S, the sole remainder N T O S would +go to the bottom.</i></p> + + +<h3>COROLARY III.</h3> + +<div class="sidenote">The more the Cone is immerged, the more impossible is +its floating.</div> + +<p class="cor_head"><i>And if we should more depress the Cone F T O, it would be so much +the more impossible that it should sustain it self afloat, the +part submerged N T O S still encreasing, and the Mass of Air +contained in the Rampart diminishing, which ever grows less, the +more the Cone submergeth.</i></p> + +<p class="cap">That Cone, therefore, that with its Base upwards, and its <i>Cuspis</i> +downwards doth swimme, being dimitted with its Base downward must of +necessity sinke. They have argued farre from the truth, therefore, who +have ascribed the cause of Natation to waters resistance of Division, +as to a passive principle, and to the breadth of the Figure, with +which the division is to be made, as the Efficient.</p> + +<p>I come in the fourth place, to collect and conclude the reason of +that which I have proposed to the Adversaries, namely,</p> +<p><span class="pagenum"><a name="Page_55" id="Page_55">[Pg 55]</a></span></p> + + + +<h2><a name="THEOREME_XII" id="THEOREME_XII"></a>THEOREME XII.</h2> + +<div class="sidenote">Solids of any Figure & greatnesse, that naturally +sink, may by help of the Air in the Rampart swimme.</div> + +<p class="def_head"><i>That it is possible <a name="tnd_55" id="tnd_55"></a><a href="#tn_55" class="tnlink" title="printer's error, missing letter r">to fo{r}m Solid Bodies,</a> of what Figure and +greatness soever, that of their own Nature goe to the Bottome; +But by the help of the Air contained in the Rampart, rest without +submerging.</i></p> + + +<p class="cap">The truth of this Proposition is sufficiently manifest in all those +Solid Figures, that determine in their uppermost part in a plane +Superficies: for making such Figures of some Matter specifically as +grave as the water, putting them into the water, so that the whole +Mass be covered, it is manifest, that they shall rest in all places, +provided, that such a Matter equall in weight to the water, may be +exactly adjusted: and they shall by consequence, rest or lie even with +the Levell of the water, without making any Rampart. If, therefore, in +respect of the Matter, such Figures are apt to rest without +submerging, though deprived of the help of the Rampart, it is +manifest, that they may admit so much encrease of Gravity, (without +encreasing their Masses) as is the weight of as much water as would be +contained within the Rampart, that is made about their upper plane +Surface: by the help of which being sustained, they shall rest afloat, +but being bathed, they shall descend, having been made graver than the +water. In Figures, therefore, that determine above in a plane, we may +cleerly comprehend, that the Rampart added or removed, may prohibit or +permit the descent: but in those Figures that go lessening upwards +towards the top, some Persons may, and that not without much seeming +Reason, doubt whether the same may be done, and especially by those +which terminate in a very acute Point, such as are your Cones and +small Piramids. Touching these, therefore, as more dubious than the +rest, I will endeavour to demonstrate, that they also lie under the +same Accident of going, or not going to the Bottom, be they of any +whatever bigness. Let therefore the Cone be A B D, made of a matter +<span class="figright" style="width: 187px;"> +<img src="images/i057.png" width="187" height="231" alt="" title="" /> +</span> +specifically as grave as the water; it is manifest that being put all +under water, it shall rest in all places (alwayes provided, that it +shall weigh exactly as much as the water, which is almost impossible +to effect) and that any small weight being added to it, it shall sink +to the bottom: but if it shall descend downwards gently, I say, that +it shall make the Rampart E S T O, and that there shall stay out of +the water the point A S T, tripple in height to the Rampart E S: which +<span class="pagenum"><a name="Page_56" id="Page_56">[Pg 56]</a></span> +is manifest, for the Matter of the Cone weighing equally with the +water, the part submerged <i>S B D T</i>, becomes indifferent to move +downwards or upwards; and the Cone <i>A S T</i>, being equall in Mass to +the water that would be contained in the concave of the Rampart <i>E S T +O</i>, shall be also equall unto it in Gravity: and, therefore, there +shall be a perfect <i>Equilibrium</i>, and, consequently, a Rest. Now here +ariseth a doubt, whether the Cone <i>A B D</i> may be made heavier, in such +sort, that when it is put wholly under water, it goes to the bottom, +but yet not in such sort, as to take from the Rampart the vertue of +sustaining it that it sink not, and, the reason of the doubt is this: +that although at such time as the Cone <i>A B D</i> is specifically as +grave as the water, the Rampart <i>E S T O</i> sustaines it, not only when +the point <i>A S T</i> is tripple in height to the Altitude of the Rampart +<i>E S</i>, but also when a lesser part is above water; [for although in +the Descent of the Cone the Point <i>A S T</i> by little and little +<span class="figleft" style="width: 191px;"> +<img src="images/i058.png" width="191" height="227" alt="" title="" /> +</span> +diminisheth, and so likewise the Rampart <i>E S T O</i>, yet the Point +diminisheth in greater proportion than the Rampart, in that it +diminisheth according to all the three Dimensions, but the Rampart +according to two only, the Altitude still remaining the same; or, if +you will, because the <a name="tnd_56" id="tnd_56"></a><a href="#tn_56" class="tnlink" title="printer's error, missing letter A">Cone <i>S {A} T</i></a> goes diminishing, according to +the proportion of the cubes of the Lines that do successively become +the Diameters of the Bases of emergent Cones, and the Ramparts +diminish according to the proportion of the Squares of the same Lines; +whereupon the proportions of the Points are alwayes Sesquialter of the +proportions of the Cylinders, contained within the Rampart; so that +if, for Example, the height of the emergent Point were double, or +equall to the height of the Rampart, in these cases, the Cylinder +contained within the Rampart, would be much greater than the said +Point, because it would be either sesquialter or tripple, by reason of +which it would perhaps serve over and above to sustain the whole Cone, +since the part submerged would no longer weigh any thing;] yet, +nevertheless, when any Gravity is added to the whole Mass of the Cone, +so that also the part submerged is not without some excesse of Gravity +above the Gravity of the water, it is not manifest, whether the +Cylinder contained within the Rampart, in the descent that the Cone +shall make, can be reduced to such a proportion unto the emergent +Point, and to such an excesse of Mass above the Mass of it, as to +compensate the excesse of the Cones Specificall Gravity above the +Gravity of the water: and the Scruple ariseth, because that howbeit in +the descent made by the Cone, the emergent Point <i>A S T</i> diminisheth, +whereby there is also a diminution of the excess of the Cones Gravity +<span class="pagenum"><a name="Page_57" id="Page_57">[Pg 57]</a></span> +above the Gravity of the water, yet the case stands so, that the +Rampart doth also contract it self, and the Cylinder contained in it +doth deminish. Nevertheless it shall be demonstrated, how that the +Cone <i>A B D</i> being of any supposed bignesse, and made at the first of +a Matter exactly equall in Gravity to the Water, if there may be +affixed to it some Weight, by means <a name="tnd_57" id="tnd_57"></a><a href="#tn_57" class="tnlink" title="printer's error, missing letter t">of which i{t} may descend</a> to the +bottom, when submerged under water, it may also by vertue of the +Rampart stay above without sinking.</p> + +<p>Let, therefore, the Cone <i>A B D</i> be of any supposed greatnesse, and +alike in specificall Gravity to the water. It is manifest, that being +put lightly into the water, it shall rest without descending; and it +<span class="figright" style="width: 189px;"> +<img src="images/i059.png" width="189" height="226" alt="" title="" /> +</span> +shall advance above water, the Point <i>A S T</i>, tripple in height to the +height of the Rampart <i>E S</i>: Now, suppose the Cone <i>A B D</i> more +depressed, so that it advance above water, only the Point <i>A I R</i>, +higher by half than the Point <i>A S T</i>, with the Rampart about it <i>C I +R N</i>. And, because, the Cone <i>A B D</i> is to the Cone <i>A I R</i>, as the +cube of the Line <i>S T</i> is to the cube of the Line <i>I R</i>, but the +Cylinder <i>E S T O</i>, is to the Cylinder <i>C I R N</i>, as the Square of <i>S +T</i> to the Square of <i>I R</i>, the Cone <i>A S T</i> shall be Octuple to the +Cone <i>A I R</i>, and the Cylinder <i>E S T O</i>, quadruple to the Cylinder <i>C +I R N</i>: But the Cone <i>A S T</i>, is equall to the Cylinder <i>E S T O</i>: +Therefore, the Cylinder <i>C I R N</i>, shall be double to the Cone <i>A I +R</i>: and the water which might be contained in the Rampart <i>C I R N</i>, +would be double in Mass and in Weight to the Cone <i>A I R</i>, and, +therefore, would be able to sustain the double of the Weight of the +Cone <i>A I R</i>: Therefore, if to the whole Cone <i>A B D</i>, there be added +as much Weight as the Gravity of the Cone <i>A I R</i>, that is to say, the +eighth part of the weight of the Cone <i>A S T</i>, it also shall be +sustained by the Rampart <i>C I R N</i>, but without that it shall go to +the bottome: the Cone <i>A B D</i>, being, by the addition of the eighth +part of the weight of the Cone <i>A S T</i>, made specifically more grave +than the water. But if the Altitude of the Cone <i>A I R</i>, were two +thirds of the Altitude of the Cone <i>A S T</i>, the Cone <i>A S T</i> would be +to the Cone <i>A I R</i>, as twenty seven to eight; and the Cylinder <i>E S T +O</i>, to the Cylinder <i>C I R N</i>, as nine to four, that is, as twenty +seven to twelve; and, therefore, the Cylinder <i>C I R N</i>, to the Cone +<i>A I R</i>, as twelve to eight; and the excess of the Cylinder <i>C I R N</i>, +above the Cone <i>A I R</i>, to the Cone <i>A S T</i>, as four to twenty seven: +therefore if to the Cone <i>A B D</i> be added so much weight as is the +four twenty sevenths of the weight of the Cone <i>A S T</i>, which is a +little more then its seventh part, it also shall continue to swimme, +<span class="pagenum"><a name="Page_58" id="Page_58">[Pg 58]</a></span> +and the height of the emergent Point shall be double to the height of +the Rampart. This that hath been demonstrated in Cones, exactly holds +in Piramides, although the one or the other should be very sharp in +their Point or Cuspis: From whence we conclude, that the same Accident +<span class="sidenote"><a name="tnd_58" id="tnd_58"></a><a href="#tn_58" class="tnlink" title="printer's error, inverted n">Natatio{n} easiest effected</a> in Figures broad toward +the top.</span> +shall so much the more easily happen in all other Figures, by how much +the less sharp the Tops shall be, in which they determine, being +assisted by more spacious Ramparts.</p> + + + + +<h2><a name="THEOREME_XIII" id="THEOREME_XIII"></a>THEOREME XIII.</h2> + +<div class="sidenote">All Figures sink or swim, upon bathing or not bathing +of their tops.</div> + +<p class="def_head"><i>All Figures, therefore, of whatever greatnesse, may go, and not +go, to the Bottom, according as their Sumities or Tops shall be +bathed or not bathed.</i></p> + + +<p class="cap">And this Accident being common to all sorts of Figures, without +exception of so much as one. Figure hath, therefore, no part in the +production of this Effect, of sometimes sinking, and sometimes again +not sinking, but only the being sometimes conjoyned to, and sometimes +seperated from, the supereminent Air: which cause, in fine, who so +shall rightly, and, as we say, with both his Eyes, consider this +business, will find that it is reduced to, yea, that it really is the +same with, the true, Naturall and primary cause of Natation or +Submersion; to wit, the excess or deficiency of the Gravity of the +water, in relation to the Gravity of that Solid Magnitude, that is +demitted into the water. For like as a Plate of Lead, as thick as the +back of a Knife, which being put into the water by it self alone goes +to the bottom, if upon it you fasten a piece of Cork four fingers +thick, doth continue afloat, for that now the Solid that is demitted +in the water, is not, as before, more grave than the water, but less, +so the Board of Ebony, of its own nature more grave than water; and, +therefore, descending to the bottom, when it is demitted by it self +alone into the water, if it shall be put upon the water, conjoyned +with an Expanded vail of Air, that together with the Ebony doth +descend, and that it be such, as that it doth make with it a compound +less grave than so much water in Mass, as equalleth the Mass already +submerged and depressed beneath the Levell of the waters Surface, it +shall not descend any farther, but shall rest, for no other than the +universall and most common cause, which is that Solid Magnitudes, less +grave <i>in specie</i> than the water, go not to the bottom.</p> + +<p>So that if one should take a Plate of Lead, as for Example, a finger +thick, and an handfull broad every way, and should attempt to make it +swimme, with putting it lightly on the water, he would lose his +Labour, because that if it should be depressed an Hairs breadth beyond +<span class="pagenum"><a name="Page_59" id="Page_59">[Pg 59]</a></span> +the possible Altitude of the Ramparts of water, it would dive and +sink; but if whilst it is going downwards, one should make certain +Banks or Ramparts about it, that should hinder the defusion of the +water upon the said Plate, the which Banks should rise so high, as +that they might be able to contain as much water, as should weigh +equally with the said Plate, it would, <a name="tnd_59a" id="tnd_59a"></a><a href="#tn_59a" class="tnlink" title="missing letter u">witho{u}t all Question,</a> descend +no lower, but would rest, as being sustained by vertue of the Air +contained within the aforesaid Ramparts: and, in short, there would be +a Vessell by this means formed with the bottom of Lead. But if the +thinness of the Lead shall be such, that a very small height of +Rampart would suffice to contain so much Air, as might keep it afloat, +it shall also rest without the Artificiall Banks or Ramparts, but yet +not without the Air, because the Air by it self makes Banks sufficient +for a small height, to resist the Superfusion of the water: so that +that which in this case swimmes, is as it were a Vessell filled with +Air, by vertue of which it continueth afloat.</p> + +<p>I will, in the last place, <a name="tnd_59b" id="tnd_59b"></a><a href="#tn_59b" class="tnlink" title="printer's error, inverted n">with an other Experime{n}t,</a> attempt to +remove all difficulties, if so be there should yet be any doubt left +in any one, touching the opperation of this *Continuity of the Air, +<span class="sidenote"><a name="tnd_59c" id="tnd_59c"></a><a href="#tn_59c" class="tnlink" title="potential printer's error, sidenote ends with comma,">* Or rather Contiguity,</a></span> +with the thin Plate which swims, and afterwards put an end to this +part of my discourse.</p> + +<p>I suppose my self to be questioning with some of my Oponents.</p> + +<p>Whether Figure have any influence upon the encrease or diminution of +the Resistance in any Weight against its being raised in the Air; and +<span class="sidenote">An Experiment of the operation of Figures, in +encreasing or lessening of the Airs Resistance of Division.</span> +I suppose, that I am to maintain the Affirmative, asserting that a +Mass of Lead, reduced to the Figure of a Ball, shall be raised with +less force, then if the same had been made into a thinne and broad +Plate, because that it in this spacious Figure, hath a great quantity +of Air to penetrate, and in that other, more compacted and contracted +very little: and to demonstrate the truth of such my Opinion, I will +hang in a small thred first the Ball or Bullet, and put that into the +water, tying the thred that upholds it to one end of the Ballance that +I hold in the Air, and to the other end I by degrees adde so much +Weight, till that at last it brings up the Ball of Lead out of the +water: to do which, suppose a Gravity of thirty Ounces sufficeth; I +afterwards reduce the said Lead into a flat and thinne Plate, the +which I likewise put into the water, suspended by three threds, which +hold it parallel to the Surface of the water, and putting in the same +manner, Weights to the other end, till such time as the Plate comes to +be raised and drawn out of the water: I finde that thirty six ounces +will not suffice to seperate it from the water, and raise it thorow +the Air: and arguing from this Experiment, I affirm, that I have fully +demonstrated the truth of my Proposition. Here my Oponents desires me +<span class="pagenum"><a name="Page_60" id="Page_60">[Pg 60]</a></span> +to look down, shewing me a thing which I had not before observed, to +wit, that in the Ascent of the Plate out of the water, it draws after +it another Plate (<i>if I may so call it</i>) of water, which before it +divides and parts from the inferiour Surface of the Plate of Lead, is +raised above the Levell of the other water, more than the thickness of +the back of a Knife: Then he goeth to repeat the Experiment with the +Ball, and makes me see, that it is but a very small quantity of water, +which cleaves to its compacted and contracted Figure: and then he +subjoynes, that its no wonder, if in seperating the thinne and broad +Plate from the water, we meet with much greater Resistance, than in +seperating the Ball, since together with the Plate, we are to raise a +great quantity of water, which occurreth not in the Ball: He telleth +me moreover, how that our Question is, whether the Resistance of +Elevation be greater in a dilated Plate of Lead, than in a Ball, and +not whether more resisteth a Plate of Lead with a great quantity of +water, or a Ball with a very little water: He sheweth me in the close, +that the putting the Plate and the Ball first into the water, to make +proofe thereby of their Resistance in the Air, is besides our case, +which treats of Elivating in the Air, and of things placed in the Air, +and not of the Resistance that is made in the Confines of the Air and +water, and by things which are part in Air and part in water: and +lastly, they make me feel with my hand, that when the thinne Plate is +in the Air, and free from the weight of the water, it is raised with +the very same Force that raiseth the Ball. Seeing, and understanding +these things, I know not what to do, unless to grant my self +convinced, and to thank such a Friend, for having made me to see that +which I never till then observed: and, being advertised by this same +Accident, to tell my Adversaries, that our Question is, whether a +Board and a Ball of Ebony, equally go to the bottom in water, and not +a Ball of Ebony and a Board of Ebony, joyned with another flat Body of +Air: and, farthermore, that we speak of sinking, and not sinking to +the bottom, in water, and not of that which happeneth in the Confines +of the water and Air to Bodies that be part in the Air, and part in +the water; nor much less do we treat of the greater or lesser Force +requisite in seperating this or that Body from the Air; not omitting +to tell them, in the last place, that the Air doth resist, and +gravitate downwards in the water, just so much as the water (if I may +so speak) gravitates and resists upwards in the Air, and that the same +Force is required to sinke a Bladder under water, that is full of Air, +as to raise it in the Air, being full of water, removing the +consideration of the weight of that Filme or Skinne, and considering +the water and the Air only. And it is likewise true, that the same +Force is required to sink a Cup or such like Vessell under water, +whilst it is full of Air, as to raise it above the Superficies of the +<span class="pagenum"><a name="Page_61" id="Page_61">[Pg 61]</a></span> +water, keeping it with the mouth downwards; whilst it is full of +water, which is constrained in the same manner to follow the Cup which +contains it, and to rise above the other water into the Region of the +Air, as the Air is forced to follow the same Vessell under the Surface +of the water, till <a name="tnd_61" id="tnd_61"></a><a href="#tn_61" class="tnlink" title="missing letter a">that in this c{a}se the water,</a> surmounting the +brimme of the Cup, breaks in, driving thence the Air, and in that +case, the said brimme coming out of the water, and arriving to the +Confines of the Air, the water falls down, and the Air sub-enters to +fill the cavity of the Cup: upon which ensues, that he no less +transgresses the Articles of the <i>Convention</i>, who produceth a Plate +conjoyned with much Air, to see if it descend to the bottom in water, +then he that makes proof of the Resistance against Elevation in Air +with a Plate of Lead, joyned with a like quantity of water.</p> + +<div class="sidenote"><i>Aristotles</i> opinion touching the Operation of Figure +examined.</div> + +<p>I have said all that I could at present think of, to maintain the +Assertion I have undertook. It remains, that I examine that which +<i>Aristotle</i> hath writ of this matter towards the end of his Book De +Cælo; wherein I shall note two things: the one that it being true as +<span class="sidenote"><i>Aristot. de Cælo</i> Lib. 4. Cap 6.</span> + +hath been demonstrated, that Figure hath nothing to do about the +moving or not moving it self upwards or downwards, its seemes that +<i>Aristotle</i> at his first falling upon this Speculation, was of the +same opinion, as in my opinion may be collected from the examination +of his words. 'Tis true, indeed, that in essaying afterwards to render +a reason of such effect, as not having in my conceit hit upon the +right, (which in the second place I will examine) it seems that he is +brought to admit the largenesse of Figure, to be interessed in this +operation. As to the first particuler, hear the precise words of +<i>Aristotle</i>.</p> + + +<p><i>Figures are not the Causes of moving simply upwards or downwards, but +of moving more slowly or swiftly, and by what means this comes to +<span class="sidenote"><i>Aristotle</i> makes not Figure the cause of Motion +absolutely, but of swift or slow motion,</span> +<span class="sidenote">Lib. 4. Cap. 6: Text. 42.</span> +pass, it is not difficult to see.</i></p> + +<p>Here first I note, that the terms being four, which fall under the +present consideration, namely, Motion, Rest, Slowly and Swiftly: And +<i>Aristotle</i> naming figures as Causes of Tardity and Velocity, +excluding them from being the Cause of absolute and simple Motion, it +seems necessary, that he exclude them on the other side, from being +the Cause of Rest, so that his meaning is this. Figures are not the +Causes of moving or not moving absolutely, but of moving quickly or +slowly: and, here, if any should say the mind of <i>Aristotle</i> is to +exclude Figures from being Causes of Motion, but yet not from being +Causes of Rest, so that the sence would be to remove from Figures, +there being the Causes of moving simply, but yet not there being +Causes of Rest, I would demand, whether we ought with <i>Aristotle</i> to +understand, that all Figures universally, are, in some manner, the +causes of Rest in those Bodies, which otherwise would move, or else +some particular Figures only, as for Example, broad and thinne +<span class="pagenum"><a name="Page_62" id="Page_62">[Pg 62]</a></span> +Figures: If all indifferently, then every Body shall rest: because +every Body hath some Figure, which is false; but if some particular +Figures only may be in some manner a Cause of Rest, as, for Example, +the broad, then the others would be in some manner the Causes of +Motion: for if from seeing some Bodies of a contracted Figure move, +which after dilated into Plates rest, may be inferred, that the +Amplitude of Figure hath a part in the Cause of that Rest; so from +seeing such like Figures rest, which afterwards contracted move, it +may with the same reason be affirmed, that the united and contracted +Figure, hath a part in causing Motion, as the remover of that which +impeded it: The which again is directly opposite to what <i>Aristotle</i> +saith, namely, that Figures are not the Causes of Motion. Besides, if +<i>Aristotle</i> had admitted and not excluded Figures from being Causes of +not moving in some Bodies, which moulded into another Figure would +move, he would have impertinently propounded in a dubitative manner, +in the words immediately following, whence it is, that the large and +thinne Plates of Lead or Iron, rest upon the water, since the Cause +was apparent, namely, the Amplitude of Figure. Let us conclude, +therefore, that the meaning of <i>Aristotle</i> in this place is to affirm, +that Figures are not the Causes of absolutely moving or not moving, +but only of moving swiftly or slowly: which we ought the rather to +believe, in regard it is indeed a most true conceipt and opinion. Now +the mind of <i>Aristotle</i> being such, and appearing by consequence, +rather contrary at the first sight, then favourable to the assertion +of the Oponents, it is necessary, that their Interpretation be not +exactly the same with that, but such, as being in part understood by +some of them, and in part by others, was set down: and it may easily +be indeed so, being an Interpretation consonent to the sence of the +more famous Interpretors, which is, that the Adverbe <i>Simply</i> or +<i>Absolutely</i>, put in the Text, ought not to be joyned to the Verbe to +<i>Move</i>, but with the Noun <i>Causes</i>: so that the purport of +<i>Aristotles</i> words, is to affirm, That Figures are not the Causes +absolutely of moving or not moving, but yet are Causes <i>Secundum +quid</i>, <i>viz.</i> in some sort; by which means, they are called Auxiliary +and Concomitant Causes: and this Proposition is received and asserted +as true by <i>Signor Buonamico Lib. 5. Cap. 28.</i> where he thus writes. +<i>There are other Causes concomitant, by which some things float, and +others sink, among which the Figures of Bodies hath the first place</i>, +&c.</p> + +<p>Concerning this Proposition, I meet with many doubts and difficulties, +for which me thinks the words of <i>Aristotle</i> are not capable of such a +construction and sence, and the difficulties are these.</p> + +<p>First in the order and disposure of the words of <i>Aristotle</i>, the +particle <i>Simpliciter</i>, or if you will <i>absoluté</i>, is conjoyned with +<span class="pagenum"><a name="Page_63" id="Page_63">[Pg 63]</a></span> +the Verb <i>to move</i>, and seperated from the Noun <i>Causes</i>, the which is +a great presumption in my favour, seeing that the writing and the Text +saith, Figures are not the Cause of moving simply upwards or +downwards, but of quicker or slower Motion: and, saith not, Figures +are not simply the Causes of moving upwards or downwards, and when the +words of a Text receive, transposed, a sence different from that which +they sound, taken in the order wherein the Author disposeth them, it +is not convenient to inverte them. And who will affirm that +<i>Aristotle</i> desiring to write a Proposition, would dispose the words +in such sort, that they should import a different, nay, a contrary +sence? contrary, I say, because understood as they are written; they +say, that Figures are not the Causes of Motion, but inverted, they +say, that Figures are the Causes of Motion, &c.</p> + +<p>Moreover, if the intent of <i>Aristotle</i> had been to say, that Figures +are not simply the Causes of moving upwards or downwards, but only +Causes <i>Secundum quid</i>, he would not have adjoyned those words, <i>but +they are Causes of the more swift or slow Motion</i>; yea, the subjoining +this would have been not only superfluous but false, for that the +whole tenour of the Proposition would import thus much. Figures are +not the absolute Causes of moving upwards or downwards, but are the +absolute Cause of the swift or slow Motion; which is not true: because +the primary Causes of greater or lesser Velocity, are by <i>Aristotle</i> +in the 4th of his <i>Physicks</i>, <i>Text. 71.</i> attributed to the greater or +lesser Gravity of Moveables, compared among themselves, and to the +greater or lesser Resistance of the <i>Medium's</i>, depending on their +greater or less Crassitude: and these are inserted by <i>Aristotle</i> as +the primary Causes; and these two only are in that place nominated: +and Figure comes afterwards to be considered, <i>Text. 74.</i> rather as an +Instrumentall Cause of the force of the Gravity, the which divides +either with the Figure, or with the <i>Impetus</i>; and, indeed, Figure by +it self without the force of Gravity or Levity, would opperate +nothing.</p> + +<p>I adde, that if <i>Aristotle</i> had an opinion that Figure had been in +some sort the Cause of moving or not moving, the inquisition which he +makes immediately in a doubtfull manner, whence it comes, that a Plate +of Lead flotes, would have been impertinent; for if but just before he +had said, that Figure was in a certain sort the Cause of moving or not +moving, he needed not to call in Question, by what Cause the Plate of +Lead swims, and then ascribing the Cause to its Figure; and framing a +discourse in this manner. Figure is a Cause <i>Secundum quid</i> of not +sinking: but, now, if it be doubted, for what Cause a thin Plate of +Lead goes not to the bottom; it shall be answered, that that proceeds +<span class="pagenum"><a name="Page_64" id="Page_64">[Pg 64]</a></span> +from its Figure: a discourse which would be indecent in a Child, much +more in <i>Aristotle</i>; For where is the occasion of doubting? And who +sees not, that if <i>Aristotle</i> had held, that Figure was in some sort a +Cause of Natation, he would without the least Hesitation have writ; +That Figure is in a certain sort the Cause of Natation, and therefore +the Plate of Lead in respect of its large and expatiated Figure swims; +but if we take the proposition of <i>Aristotle</i> as I say, and as it is +written, and as indeed it is true, the ensuing words come in very +oppositely, as well in the introduction of swift and slow, as in the +question, which very pertinently offers it self, and would say thus +much.</p> + +<p>Figures are not the Cause of moving or not moving simply upwards or +downwards, but of moving more quickly or slowly: But if it be so, the +Cause is doubtfull, whence it proceeds, that a Plate of Lead or of +Iron broad and thin doth swim, &c. And the occasion of the doubt is +obvious, because it seems at the first glance, that the Figure is the +Cause of this Natation, since the same Lead, or a less quantity, but +in another Figure, goes to the bottom, and we have already affirmed, +that the Figure hath no share in this effect.</p> + +<p>Lastly, if the intent of <i>Aristotle</i> in this place had been to say, +that Figures, although not absolutely, are at least in some measure +the Cause of moving or not moving: I would have it considered, that he +names no less the Motion upwards, than the other downwards: and +because in exemplifying it afterwards, he produceth no other +Experiments than of a Plate of Lead, and Board of Ebony, Matters that +of their own Nature go to the bottom, but by vertue (as our +Adversaries say) of their Figure, rest afloat; it is fit that they +should produce some other Experiment of those Matters, which by their +Nature swims, but retained by their Figure rest at the bottom. But +since this is impossible to be done, we conclude, that <i>Aristotle</i> in +this place, hath not attributed any action to the Figure of simply +moving or not moving.</p> + +<p>But though he hath exquisitely Philosophiz'd, in investigating the +solution of the doubts he proposeth, yet will I not undertake to +maintain, rather various difficulties, that present themselves unto +me, give me occasion of suspecting that he hath not entirely displaid +unto us, the true Cause of the present Conclusion: which difficulties +I will propound one by one, ready to change opinion, whenever I am +shewed, that the Truth is different from what I say; to the confession +whereof I am much more inclinable than to contradiction.</p> + +<div class="sidenote"><i>Aristotle</i> erred in affirming a Needle dimitted long +wayes to sink.</div> + +<p><i>Aristotle</i> having propounded the Question, whence it proceeds, that +broad Plates of Iron or Lead, float or swim; he addeth (as it were +strengthening the occasion of doubting) forasmuch as other things, +less, and less grave, be they round or long, as for instance a Needle +<span class="pagenum"><a name="Page_65" id="Page_65">[Pg 65]</a></span> +go to the bottom. Now I here doubt, or rather am certain that a Needle +put lightly upon the water, rests afloat, no less than the thin Plates +of Iron or Lead. I cannot believe, albeit it hath been told me, that +some to defend <i>Aristotle</i> should say, that he intends a Needle +demitted not longwayes but endwayes, and with the Point downwards; +nevertheless, not to leave them so much as this, though very weak +refuge, and which in my judgement <i>Aristotle</i> himself would refuse, I +say it ought to be understood, that the Needle must be demitted, +according to the Dimension named by <i>Aristotle</i>, which is the length: +because, if any other Dimension than that which is named, might or +ought to be taken, I would say, that even the Plates of Iron and Lead, +sink to the bottom, if they be put into the water edgewayes and not +flatwayes. But because <i>Aristotle</i> saith, broad Figures go not to the +bottom, it is to be understood, being demitted broadwayes: and, +therefore, when he saith, long Figures as a Needle, albeit light, rest +not afloat, it ought to be understood of them when demitted longwayes.</p> + +<p><i>Moreover, to say that</i> Aristotle <i>is to be understood of the +Needle demitted with the Point downwards, is to father upon him a +great impertinency; for in this place he saith, that little +Particles of Lead or Iron, if they be round or long as a Needle, do +sink to the bottome; so that by his Opinion, a Particle or small +Grain of Iron cannot swim: and if he thus believed, what a great +folly would it be to subjoyn, that neither would a Needle demitted +endwayes swim? And what other is such a Needle, but many such like +Graines accumulated one upon another? It was too unworthy of such a +man to say, that one single Grain of Iron could not swim, and that +neither can it swim, though you put a hundred more upon it.</i></p> + +<p>Lastly, either <i>Aristotle</i> believed, that a Needle demitted longwayes +upon the water, would swim, or he believed that it would not swim: If +he believed it would not swim, he might well speak as indeed he did; +but if he believed and knew that it would float, why, together with +the dubious Problem of the Natation of broad Figures, though of +ponderous Matter, hath he not also introduced the Question; whence it +proceeds, that even long and slender Figures, howbeit of Iron or Lead +do swim? And the rather, for that the occasion of doubting seems +greater in long and narrow Figures, than in broad and thin, as from +<i>Aristotles</i> not having doubted of it, is manifested.</p> + +<p>No lesser an inconvenience would they fasten upon <i>Aristotle</i>, who in +his defence should say, that he means a Needle pretty thick, and not a +small one; for take it for granted to be intended of a small one; and +<span class="pagenum"><a name="Page_66" id="Page_66">[Pg 66]</a></span> +it shall suffice to reply, that he believed that it would swim; and I +will again charge him with having avoided a more wonderfull and +intricate Probleme, and introduced the more facile and less +wonderfull.</p> + +<p>We say freely therefore, that <i>Aristotle</i> did hold, that only the +broad Figure did swim, but the long and slender, such as a Needle, +not. The which nevertheless is false, as it is also false in round +Bodies: because, as from what hath been predemonstrated, may be +gathered, little Balls of Lead and Iron, do in like manner swim.</p> + +<div class="sidenote"><i>Aristotle</i> affirmeth some Bodies volatile for their +Minuity, Text. 42.</div> + +<p>He proposeth likewise another Conclusion, which likewise seems +different from the truth, and it is, That some things, by reason of +their littleness fly in the Air, as the small dust of the Earth, and +the thin leaves of beaten Gold: but in my Opinion, Experience shews +us, that that happens not only in the Air, but also in the water, in +which do descend, even those Particles or Atomes of Earth, that +disturbe it, whose minuity is such, that they are not deservable, save +only when they are many hundreds together. Therefore, the dust of the +Earth, and beaten Gold, do not any way sustain themselves in the Air, +but descend downwards, and only fly to and again in the same, when +strong Windes raise them, or other agitations of the Air commove them: +and this also happens in the commotion of the water, which raiseth its +Sand from the bottom, and makes it muddy. But <i>Aristotle</i> cannot mean +this impediment of the commotion, of which he makes no mention, nor +names other than the lightness of such Minutiæ or Atomes, and the +Resistance of the Crassitudes of the Water and Air, by which we see, +that he speakes of a calme, and not disturbed and agitated Air: but in +that case, neither Gold nor Earth, be they never so small, are +sustained, but speedily descend.</p> + +<div class="sidenote"><i>Democritus</i> placed the Cause of Natation in certain +fiery Atomes.</div> + +<p>He passeth next to confute <i>Democritus</i>, which, by his Testimony would +<span class="sidenote"><i>Aristot. De Cælo</i> lib. 4. cap. 6. text. 43.</span> +have it, that some Fiery Atomes, which continually ascend through the +water, do spring upwards, and sustain those grave Bodies, which are +very broad, and that the narrow descend to the bottom, for that but a +small quantity of those Atomes, encounter and resist them.</p> + +<div class="sidenote"><i>Democritus</i> confuted by <i>Aristotle</i>, text 43.</div> + +<p>I say, <i>Aristotle</i> confutes this position, saying, that that should +much more occurre in the Air, as the same <i>Democritus</i> instances +against himself, but after he had moved the objection, he slightly +resolves it, with saying, that those Corpuscles which ascend in the +Air, make not their <i>Impetus</i> conjunctly. Here I will not say, that +the reason alledged by <i>Democritus</i> is true, but I will only say, it +<span class="sidenote"><i>Aristotles</i> confutation of <i>Democritus</i> refuted by the +Author.</span> +seems in my judgement, that it is not wholly confuted by <i>Aristotle</i>, +whilst he saith, that were it true, that the calid ascending Atomes, +should sustain Bodies grave, but very broad, it would much more be +done in the Air, than in Water, for that haply in the Opinion of +<span class="pagenum"><a name="Page_67" id="Page_67">[Pg 67]</a></span> +<i>Aristotle</i>, the said calid Atomes ascend with much greater Force and +Velocity through the Air, than through the water. And if this be so, +as I verily believe it is, the Objection of <i>Aristotle</i> in my +judgement seems to give occasion of suspecting, that he may possibly +be deceived in more than one particular: First, because those calid +Atomes, (whether they be Fiery Corpuscles, or whether they be +Exhalations, or in short, whatever other matter they be, that ascends +upwards through the Air) cannot be believed to mount faster through +Air, than through water: but rather on the contrary, they peradventure +move more impetuously through the water, than through the Air, as hath +been in part demonstrated above. And here I cannot finde the reason, +why <i>Aristotle</i> seeing, that the descending Motion of the same +Moveable, is more swift in Air, than in water, hath not advertised us, +that from the contrary Motion, the contrary should necessarily follow; +to wit, that it is more swift in the water, than in the Air: for since +that the Moveable which descendeth, moves swifter through the Air, +than through the water, if we should suppose its Gravity gradually to +diminish, it would first become such, that descending swiftly through +the Air, it would descend but slowly through the water: and then +again, it might be such, that descending in the Air, it should ascend +in the water: and being made yet less grave, it shall ascend swiftly +through the water, and yet descend likewise through the Air: and in +short, before it can begin to ascend, though but slowly through the +Air, it shall ascend swiftly through the water: how then is it true, +that ascending Moveables move swifter through the Air, than through +the water?</p> + +<p>That which hath made <i>Aristotle</i> believe, the Motion of Ascent to be +swifter in Air, than in water, was first, the having referred the +Causes of slow and quick, as well in the Motion of Ascent, as of +Descent, only to the diversity of the Figures of the Moveable, and to +the more or less Resistance of the greater or lesser Crassitude, or +Rarity of the <i>Medium</i>; not regarding the comparison of the Excesses +of the Gravities of the Moveables, and of the <i>Mediums</i>: the which +notwithstanding, is the most principal point in this affair: for if +the augmentation and diminution of the Tardity or Velocity, should +have only respect to the Density or Rarity of the <i>Medium</i>, every Body +that descends in Air, would descend in water: because whatever +difference is found between the Crassitude of the water, and that of +the Air, may well be found between the Velocity of the same Moveable +in the Air, and some other Velocity: and this should be its proper +Velocity in the water, which is absolutely false. The other occasion +is, that he did believe, that like as there is a positive and +intrinsecall Quality, whereby Elementary Bodies have a propension of +moving towards the Centre of the Earth, so there is another likewise +<span class="pagenum"><a name="Page_68" id="Page_68">[Pg 68]</a></span> +intrinsecall, whereby some of those Bodies have an <i>Impetus</i> of flying +<span class="sidenote">Lib. 4. Cap. 5.</span> +the Centre, and moving upwards: by Vertue of which intrinsecall +Principle, called by him Levity, the Moveables which have that same +Motion more easily penetrate the more subtle <i>Medium</i>, than the more +dense: but such a Proposition appears likewise uncertain, as I have +above hinted in part, and as with Reasons and Experiments, I could +demonstrate, did not the present Argument importune me, or could I +dispatch it in few words.</p> + +<p>The Objection therefore of <i>Aristotle</i> against <i>Democritus</i>, whilst he +saith, that if the Fiery ascending Atomes should sustain Bodies grave, +but of a distended Figure, it would be more observable in the Air than +in the water, because such Corpuscles move swifter in that, than in +this, is not good; yea the contrary would evene, for that they ascend +more slowly through the Air: and, besides their moving slowly, they +ascend, not united together, as in the water, but discontinue, and, as +we say, scatter: And, therefore, as <i>Democritus</i> well replyes, +resolving the instance they make not their push or <i>Impetus</i> +conjunctly.</p> + +<p><i>Aristotle</i>, in the second place, deceives himself, whilst he will +have the said grave Bodies to be more easily sustained by the said +Fiery ascending Atomes in the Air than in the Water: not observing, +that the said Bodies are much more grave in that, than in this, and +that such a Body weighs ten pounds in the Air, which will not in the +water weigh 1/2 an ounce; how can it then be more easily sustained in +the Air, than in the Water?</p> + +<div class="sidenote"><i>Democritus</i> confuted by the Authour.</div> + +<p>Let us conclude, therefore, that <i>Democritus</i> hath in this particular +better Philosophated than <i>Aristotle</i>. But yet will not I affirm, that +<i>Democritus</i> hath reason'd rightly, but I rather say, that there is a +manifest Experiment that overthrows his Reason, and this it is, That +if it were true, that calid ascending Atomes should uphold a Body, +that if they did not hinder, would go to the bottom, it would follow, +that we may find a Matter very little superiour in Gravity to the +water, the which being reduced into a Ball, or other contracted +Figure, should go to the bottom, as encountring but few Fiery Atomes; +and which being distended afterwards into a dilated and thin Plate, +should come to be thrust upwards by the impulsion of a great Multitude +of those Corpuscles, and at last carried to the very Surface of the +water: which wee see not to happen; Experience shewing us, that a Body +<i>v. gra.</i> of a Sphericall Figure, which very hardly, and with very +great leasure goeth to the bottom, will rest there, and will also +descend thither, being reduced into whatsoever other distended Figure. +We must needs say then, either that in the water, there are no such +ascending Fiery Atoms, or if that such there be, that they are not +able to raise and lift up any Plate of a Matter, that without them +<span class="pagenum"><a name="Page_69" id="Page_69">[Pg 69]</a></span> +would go to the bottom: Of which two Positions, I esteem the second to +be true, understanding it of water, constituted in its naturall +Coldness. But if we take a Vessel of Glass, or Brass, or any other +hard matter, full of cold water, within which is put a Solid of a flat +or concave Figure, but that in Gravity exceeds the water so little, +that it goes slowly to the bottom; I say, that putting some burning +Coals under the said Vessel, as soon as the new Fiery Atomes shall +have penetrated the substance of the Vessel, they shall without doubt, +ascend through that of the water, and thrusting against the foresaid +Solid, they shall drive it to the Superficies, and there detain it, as +long as the incursions of the said Corpuscles shall last, which +ceasing after the removall of the Fire, the Solid being abandoned by +its supporters, shall return to the bottom.</p> + +<p>But <i>Democritus</i> notes, that this Cause only takes place when we +treat of raising and sustaining of Plates of Matters, but very little +heavier than the water, or extreamly thin: but in Matters very grave, +and of some thickness, as Plates of Lead or other Mettal, that same +Effect wholly ceaseth: In Testimony of which, let's observe that such +Plates, being raised by the Fiery Atomes, ascend through all the depth +of the water, and stop at the Confines of the Air, still staying under +water: but the Plates of the Opponents stay not, but only when they +have their upper Superficies dry, nor is there any means to be used, +that when they are within the water, they may not sink to the bottom. +The cause, therefore, of the Supernatation of the things of which +<i>Democritus</i> speaks is one, and that of the Supernatation of the +things of which we speak is another. But, returning to <i>Aristotle</i>, +<span class="sidenote"><i>Aristotle</i> shews his desire of finding <i>Democritus</i> +in an Error, to exceed that of discovering Truth.</span> +methinks that he hath more weakly confuted <i>Democritus</i>, than +<i>Democritus</i> himself hath done: For <i>Aristotle</i> having propounded the +Objection which he maketh against him, and opposed him with saying, +that if the calid ascendent Corpuscles were those that raised the thin +Plate, much more then would such a Solid be raised and born upwards +through the Air, it sheweth that the desire in <i>Aristotle</i> to detect +<i>Democritus</i>, was predominate over the exquisiteness of Solid +Philosophizing: which desire of his he hath discovered in other +occasions, and that we may not digress too far from this place, in the +Text precedent to this Chapter which we have in hand; where he +<span class="sidenote">Cap. 5. Text 41.</span> +attempts to confute the same <i>Democritus</i> for that he, not contenting +himself with names only, had essayed more particularly to declare what +things Gravity and Levity were; that is, the Causes of descending and +ascending, (and had introduced Repletion and Vacuity) ascribing this +to Fire, by which it moves upwards, and that to the Earth, by which it +descends; afterwards attributing to the Air more of Fire, and to the +water more of Earth. But <i>Aristotle</i> desiring a positive Cause, even +of ascending Motion, and not as <i>Plato</i>, or these others, a simple +<span class="pagenum"><a name="Page_70" id="Page_70">[Pg 70]</a></span> +negation, or privation, such as Vacuity would be in reference to +Repletion, argueth against <i>Democritus</i> and saith: If it be true, as +<span class="sidenote">Id. ibid.</span> +you suppose, then there shall be a great Mass of water, which shall +have more of Fire, than a small Mass of Air, and a great Mass of Air, +which shall have more of Earth than a little Mass of water, whereby it +would ensue, that a great Mass of Air, should come more swiftly +downwards, than a little quantity of water: But that is never in any +case soever: Therefore <i>Democritus</i> discourseth erroneously.</p> + +<p>But in my opinion, the Doctrine of <i>Democritus</i> is not by this +allegation overthrown, but if I erre not, the manner of <i>Aristotle</i> +deduction either concludes not, or if it do conclude any thing, it may +with equall force be restored against himself. <i>Democritus</i> will grant +to <i>Aristotle</i>, that there may be a great Mass of Air taken, which +contains more Earth, than a small quantity of water, but yet will +deny, that such a Mass of Air, shall go faster downwards than a little +water, and that for many reasons. First, because if the greater +quantity of Earth, contained in the great Mass of Air, ought to cause +a greater Velocity than a less quantity of Earth, contained in a +little quantity of water, it would be necessary, first, that it were +true, that a greater Mass of pure Earth, should move more swiftly than +a less: But this is false, though <i>Aristotle</i> in many places affirms +it to be true: because not the greater absolute, but the greater +specificall Gravity, is the cause of greater Velocity: nor doth a Ball +<span class="sidenote">The greater Specificall, not the greater absolute +Gravity, is the Cause of Velocity.</span> +of Wood, weighing ten pounds, descend more swiftly than one weighing +ten Ounces, and that is of the same Matter: but indeed a Bullet of +Lead of four Ounces, descendeth more swiftly than a Ball of Wood of +twenty Pounds: because the Lead is more <i>grave in specie</i> than the +Wood. Therefore, its not necessary, that a great Mass of Air, by +reason of the much Earth contained in it, do descend more swiftly than +a little Mass of water, but on the contrary, any whatsoever Mass of +<span class="sidenote">Any Mass of water shal move more swiftly, than any of +Air, and why.</span> +water, shall move more swiftly than any other of Air, by reason the +participation of the terrene parts <i>in specie</i> is greater in the +water, than in the Air. Let us note, in the second place, how that in +multiplying the Mass of the Air, we not only multiply that which is +therein of terrene, but its Fire also: whence the Cause of ascending, +no less encreaseth, by vertue of the Fire, than that of descending on +the account of its multiplied Earth. It was requisite in increasing +the greatness of the Air, to multiply that which it hath of terrene +only, leaving its Fire in its first state, for then the terrene parts +of the augmented Air, overcoming the terrene parts of the small +quantity of water, it might with more probability have been pretended, +that the great quantity of Air, ought to descend with a greater +<i>Impetus</i>, than the little quantity of water.</p> + +<p><span class="pagenum"><a name="Page_71" id="Page_71">[Pg 71]</a></span></p> +<p>Therefore, the Fallacy lyes more in the Discourse of <i>Aristotle</i>, than +in that of <i>Democritus</i>, who with severall other Reasons might oppose +<i>Aristotle</i>, and alledge; If it be true, that the extreame Elements be +one simply grave, and the other simply light, and that the mean +Elements participate of the one, and of the other Nature; but the Air +more of Levity, and the water more of Gravity, then there shall be a +great Mass of Air, whose Gravity shall exceed the Gravity of a little +quantity of water, and therefore such a Mass of Air shall descend more +swiftly than that little water: But that is never seen to occurr: +Therefore its not true, that the mean Elements do participate of the +one, and the other quality. This argument is fallacious, no less than +the other against <i>Democritus</i>.</p> + +<p>Lastly, <i>Aristotle</i> having said, that if the Position of <i>Democritus</i> +were true, it would follow, that a great Mass of Air should move more +swiftly than a small Mass of water, and afterwards subjoyned, that +that is never seen in any Case: methinks others may become desirous to +know of him in what place this should evene, which he deduceth against +<i>Democritus</i>, and what Experiment teacheth us, that it never falls out +so. To suppose to see it in the Element of water, or in that of the +Air is vain, because neither doth water through water, nor Air through +Air move, nor would they ever by any whatever participation others +assign them, of Earth or of Fire: the Earth, in that it is not a Body +fluid, and yielding to the mobility of other Bodies, is a most +improper place and <i>Medium</i> for such an Experiment: <i>Vacuum</i>, +according to the same <i>Aristotle</i> himself, there is none, and were +there, nothing would move in it: there remains the Region of Fire, but +being so far distant from us, what Experiment can assure us, or hath +assertained <i>Aristotle</i> in such sort, that he should as of a thing +most obvious to sence, affirm what he produceth in confutation of +<i>Democritus</i>, to wit, that a great Mass of Air, is moved no swifter +than a little one of water? But I will dwell no longer upon this +matter, whereon I have spoke sufficiently: but leaving <i>Democritus</i>, I +return to the Text of <i>Aristotle</i>, wherein he goes about to render the +true reason, how it comes to pass, that the thin Plates of Iron or +Lead do swim on the water; and, moreover, that Gold it self being +beaten into thin Leaves, not only swims in water, but flyeth too and +again in the Air. He supposeth that of Continualls, some are easily +<span class="sidenote"><i>De Cælo</i> l. 4. c. 6. t. 44.</span> +divisible, others not: and that of the easily divisible, some are more +so, and some less: and these he affirms we should esteem the Causes. +He addes that that is easily divisible, which is well terminated, and +the more the more divisible, and that the Air is more so, than the +water, and the water than the Earth. And, lastly, supposeth that in +each kind, the lesse quantity is easlyer divided and broken than the +greater.</p> +<p><span class="pagenum"><a name="Page_72" id="Page_72">[Pg 72]</a></span></p> + +<p>Here I note, that the Conclusions of <i>Aristotle</i> in generall are all +true, but methinks, that he applyeth them to particulars, in which +they have no place, as indeed they have in others, as for Example, Wax +is more easily divisible than Lead, and Lead than Silver, inasmuch as +Wax receives all the terms more easlier than Lead, and Lead than +Silver. Its true, moreover, that a little quantity of Silver is +easlier divided than a great Mass: and all these Propositions are +true, because true it is, that in Silver, Lead and Wax, there is +simply a Resistance against Division, and where there is the absolute, +there is also the respective. But if as well in water as in Air, there +be no Renitence against simple Division, how can we say, that the +water is easlier divided than the Air? We know not how to extricate +our selves from the Equivocation: whereupon I return to answer, that +Resistance of absolute Division is one thing, and Resistance of +Division made with such and such Velocity is another. But to produce +Rest, and to abate the Motion, the Resistance of absolute Division is +necessary; and the Resistance of speedy Division, causeth not Rest, +but slowness of Motion. But that as well in the Air, as in water, +there is no Resistance of simple Division, is manifest, for that there +is not found any Solid Body which divides not the Air, and also the +water: and that beaten Gold, or small dust, are not able to superate +the Resistance of the Air, is contrary to that which Experience shews +us, for we see Gold and Dust to go waving to and again in the Air, and +at last to descend downwards, and to do the same in the water, if it +be put therein, and separated from the Air. And, because, as I say, +neither the water, nor the Air do resist simple Division, it cannot be +said, that the water resists more than the Air. Nor let any object +unto me, the Example of most light Bodies, as a Feather, or a little +of the pith of Elder, or water-reed that divides the Air and not the +water, and from this infer, that the Air is easlier divisible than the +water; for I say unto them, that if they do well observe, they shall +see the same Body likewise divide the Continuity of the water, and +<span class="sidenote"><i>Archimed. De Insident. humi</i> lib. 2. prop. 1.</span> +submerge in part, and in such a part, as that so much water in Mass +would weigh as much as the whole Solid. And if they shal yet persist +in their doubt, that such a Solid sinks not through inability to +divide the water, I will return them this reply, that if they put it +under water, and then let it go, they shall see it divide the water, +and presently ascend with no less celerity, than that with which it +divided the Air in descending: so that to say that this Solid ascends +in the Air, but that coming to the water, it ceaseth its Motion, and +therefore the water is more difficult to be divided, concludes +nothing: for I, on the contrary, will propose them a piece of Wood, or +of Wax, which riseth from the bottom of the water, and easily divides +its Resistance, which afterwards being arrived at the Air, stayeth +<span class="pagenum"><a name="Page_73" id="Page_73">[Pg 73]</a></span> +there, and hardly toucheth it; whence I may aswell say, that the water +is more easier divided than the Air.</p> + +<p>I will not on this occasion forbear to give warning of another fallacy +of these persons, who attribute the reason of sinking or swimming to +the greater or lesse Resistance of the Crassitude of the water against +Division, making use of the example of an Egg, which in sweet water +goeth to the bottom, but in salt water swims; and alledging for the +cause thereof, the faint Resistance of fresh water against Division, +and the strong Resistance of salt water. But if I mistake not, from +the same Experiment, we may aswell deduce the quite contrary; namely, +that the fresh water is more dense, and the salt more tenuous and +subtle, since an Egg from the bottom of salt water speedily ascends to +the top, and divides its Resistance, which it cannot do in the fresh, +in whose bottom it stays, being unable to rise upwards. Into such like +perplexities, do false Principles Lead men: but he that rightly +Philosophating, shall acknowledge the excesses of the Gravities of the +Moveables and of the Mediums, to be the Causes of those effects, will +say, that the Egg sinks to the bottom in fresh water, for that it is +more grave than it, and swimeth in the salt, for that its less grave +than it: and shall without any absurdity, very solidly establish his +Conclusions.</p> + +<p>Therefore the reason totally ceaseth, that <i>Aristotle</i> subjoyns in the +Text saying; The things, therefore, which have great breadth remain +<span class="sidenote">Text 45.</span> +above, because they comprehend much, and that which is greater, is not +easily divided. Such discoursing ceaseth, I say, because its not true, +that there is in water or in Air any Resistance of Division; besides +that the Plate of Lead when it stays, hath already divided and +penetrated the Crassitude of the water, and profounded it self ten or +twelve times more than its own thickness: besides that such Resistance +of Division, were it supposed to be in the water, could not rationally +be affirmed to be more in its superiour parts than in the middle, and +lower: but if there were any difference, the inferiour should be the +more dense, so that the Plate would be no less unable to penetrate the +lower, than the superiour parts of the water; nevertheless we see that +no sooner do we wet the superiour Superficies of the Board or thin +Piece of Wood, but it precipitatly, and without any retension, +descends to the bottom.</p> + +<p>I believe not after all this, that any (thinking perhaps thereby to +defend <i>Aristotle</i>) will say, that it being true, that the much water +resists more than the little, the said Board being put lower +descendeth, because there remaineth a less Mass of water to be divided +by it: because if after the having seen the same Board swim in four +Inches of water, and also after that in the same to sink, he shall try +the same Experiment upon a profundity of ten or twenty fathom water, +he shall see the very self same effect. And here I will take occasion +<span class="pagenum"><a name="Page_74" id="Page_74">[Pg 74]</a></span> +to remember, for the removall of an Error that is too common; That +that Ship or other whatsoever Body, that on the depth of an hundred or +a thousand fathom, swims with submerging only six fathom of its own +height, [<i>or in the Sea dialect, that draws six fathom water</i>] shall +swim in the same manner in water, that hath but six fathom and half an +Inch of depth. Nor do I on the other side, think that it can be said, +<span class="sidenote">A Ship that in 100 Fathome water draweth 6 Fathome, +shall float in 6 Fathome and 1/2 an Inch of depth.</span> +that the superiour parts of the water are the more dense, although a +most grave Authour hath esteemed the superiour water in the Sea to be +so, grounding his opinion upon its being more salt, than that at the +bottom: but I doubt the Experiment, whether hitherto in taking the +water from the bottom, the Observatour did not light upon some spring +of fresh water there spouting up: but we plainly see on the contrary, +the fresh Waters of Rivers to dilate themselves for some miles beyond +their place of meeting with the salt water of the Sea, without +descending in it, or mixing with it, unless by the intervention of +some commotion or turbulency of the Windes.</p> + +<p>But returning to <i>Aristotle</i>, I say, that the breadth of Figure hath +nothing to do in this business more or less, because the said Plate of +Lead, or other Matter, cut into long Slices, swim neither more nor +less; and the same shall the Slices do, being cut anew into little +<span class="sidenote">Thickness not breadth of Figure to be respected in +Natation.</span> +pieces, because its not the breadth but the thickness that operates in +this business. I say farther, that in case it were really true, that +the Renitence to Division were the proper Cause of swimming, the +<span class="sidenote">Were Renitence the cause of Natation, breadth of Figure +would hinder the swiming of Bodies.</span> +Figures more narrow and short, would much better swim than the more +spacious and broad, so that augmenting the breadth of the Figure, the +facility of supernatation will be deminished, and decreasing, that +this will encrease.</p> + +<p>And for declaration of what I say, consider that when a thin Plate of +Lead descends, dividing the water, the Division and discontinuation is +made between the parts of the water, invironing the perimeter or +Circumference of the said Plate, and according to the bigness greater +or lesser of that circuit, it hath to divide a greater or lesser +quantity of water, so that if the circuit, suppose of a Board, be ten +Feet in sinking it flatways, it is to make the seperation and +division, and to so speak, an incission upon ten Feet of water; and +likewise a lesser Board that is four Feet in Perimeter, must make an +incession of four Feet. This granted, he that hath any knowledge in +Geometry, will comprehend, not only that a Board sawed in many long +thin pieces, will much better float than when it was entire, but that +all Figures, the more short and narrow they be, shall so much the +better swim. Let the Board A B C D be, for Example, eight Palmes long, +and five broad, its circuit shall be twenty six Palmes; and so many +must the incession be, which it shall make in the water to descend +therein: <a name="tnd_74" id="tnd_74"></a><a href="#tn_74" class="tnlink" title="printer's error, ir for it">but if we do saw ir,</a> as suppose into eight little pieces, +<span class="pagenum"><a name="Page_75" id="Page_75">[Pg 75]</a></span> +according to the Lines E F, G H, <a name="tnd_75" id="tnd_75"></a><a href="#tn_75" class="tnlink" title="unclear symbol in original text">{&}c. making seven Segments,</a> we must +adde to the twenty six Palmes of the circuit of the whole Board, +seventy others; whereupon the eight little pieces so cut and +seperated, have to cut ninty six Palmes of water. And, if moreover, we +<span class="figright" style="width: 199px;"> +<img src="images/i077.png" width="199" height="254" alt="" title="" /> +</span> +cut each of the said pieces into five parts, reducing them into +Squares, to the circuit of ninty six Palmes, with four cuts of eight +Palmes apiece; we shall adde also sixty four Palmes, whereupon the +said Squares to descend in the water, must divide one hundred and +sixty Palmes of water, but the Resistance is much greater than that of +twenty six; therefore to the lesser Superficies, we shall reduce them, +so much the more easily will they float: and the same will happen in +all other Figures, whose Superficies are simular amongst themselves, +but different in bigness: because the said Superficies, being either +deminished or encreased, always diminish or encrease their Perimeters +in subduple proportion; to wit, the Resistance that they find in +penetrating the water; therefore the little pieces gradually swim, +with more and more facility as their breadth is lessened.</p> + +<p><i>This is manifest; for keeping still the same height of the Solid, +with the same proportion as the Base encreaseth or deminisheth, +doth the said Solid also encrease or diminish; whereupon the Solid +more diminishing than the Circuit, the Cause of Submersion more +diminisheth than the Cause of Natation: And on the contrary, the +Solid more encreasing than the Circuit, the Cause of Submersion +encreaseth more, that of Natation less.</i></p> + +<p>And this may all be deduced out of the Doctrine of <i>Aristotle</i> against +his own Doctrine.</p> + +<div class="sidenote">Lib. 4. c. 6. Text 45.</div> + +<p>Lastly, to that which we read in the latter part of the Text, that is +to say, that we must compare the Gravity of the Moveable with the +Resistance of the Medium against Division, because if the force of the +Gravity exceed the Resistance of the <i>Medium</i>, the Moveable will +descend, if not it will float. I need not make any other answer, but +that which hath been already delivered; namely, that its not the +Resistance of absolute Division, (which neither is in Water nor Air) +but the Gravity of the <i>Medium</i> that must be compared with the Gravity +of the Moveables; and if that of the <i>Medium</i> be greater, the Moveable +shall not descend, nor so much as make a totall Submersion, but a +partiall only; because in the place which it would occupy in the +water, there must not remain a Body that weighs less than a like +quantity of water: but if the Moveable be more grave, it shall descend +to the bottom, and possess a place where it is more conformable for it +<span class="pagenum"><a name="Page_76" id="Page_76">[Pg 76]</a></span> +to remain, than another Body that is less grave. And this is the only +true proper and absolute Cause of Natation and Submersion, so that +nothing else hath part therein: and the Board of the Adversaries +swimmeth, when it is conjoyned with as much Air, as, together with it, +doth form a Body less grave than so much water as would fill the place +that the said Compound occupyes in the water; but when they shall +demit the simple Ebony into the water, according to the Tenour of our +Question, it shall alwayes go to the bottom, though it were as thin as +a Paper.</p> + +<p> </p> + +<div class="figcenter" style="width: 609px;"> +<img src="images/i078a.png" width="609" height="46" alt="" title="" /> +</div> + +<p> </p> + +<p class="f_end">FINIS.</p> + +<p> </p> +<p> </p> + +<div class="figcenter" style="width: 368px;"> +<img src="images/i078b.png" width="368" height="295" alt="" title="" /> +</div> + + +<hr style="width: 65%;" /> + + +<div class="bbox"> + <p><b>Detailed Transcriber's Notes</b></p> + + <p>The text has been made to match the original text as much as + possible including variation in spelling, punctuation, italics etc. + The following, details apparent printer's errors as well as changes + or additions to aid readability of text.</p> + + <p>Page <a href="#Page_1">1</a><a name="tn_1" id="tn_1"></a>, missing full stop after abbreviation gr., <a href="#tnd_1">'0 gr 54 min.'</a>.</p> + + <p>Page <a href="#Page_3">3</a><a name="tn_3a" id="tn_3a"></a>, sidenote, missing space between words, <a href="#tnd_3a">'the Authority ofan Author.'</a>.</p> + + <p>Page <a href="#Page_3">3</a><a name="tn_3b" id="tn_3b"></a>, printer's error, augmentarion for augmentation, <a href="#tnd_3b">'and + augmentarion of Masse'</a>.</p> + + <p>Page <a href="#Page_4">4</a><a name="tn_4a" id="tn_4a"></a>, missing letter t, <a href="#tnd_4a">'tha{t} that proceeded not'</a>.</p> + + <p>Page <a href="#Page_4">4</a><a name="tn_4b" id="tn_4b"></a>, printer's error or inconsistent punctuation, <a href="#tnd_4b">'my paynes and + time. and although'</a>.</p> + + <p>Page <a href="#Page_6">6</a><a name="tn_6" id="tn_6"></a>, inconsistent punctuation, full stop after axiome where as + there are none after those following, <a href="#tnd_6">'AXIOME. I.'</a>.</p> + + <p>Page <a href="#Page_9">9</a><a name="tn_9" id="tn_9"></a>, missing full stop added to end of paragraph, <a href="#tnd_9">'or else an + upright Prisme.'</a>.</p> + + <p>Page <a href="#Page_11">11</a><a name="tn_11" id="tn_11"></a>, printer's error, missing letter C in illustration, <a href="#tnd_11">'the + Prisme A C D B to be placed'</a>.</p> + + <p>Page <a href="#Page_15">15</a><a name="tn_15" id="tn_15"></a>, printer's error or archaic lettering, final y looking like a + 7 in original text, <a href="#tnd_15">'and of the Specifick Gravit{y}'</a>.</p> + + <p>Page <a href="#Page_16">16</a><a name="tn_16b" id="tn_16b"></a>, letter N for T in text to refer to + illustration, <a href="#tnd_16b">if the Vessell E N S F'</a>.</p> + + <p>Page <a href="#Page_16">16</a><a name="tn_16" id="tn_16"></a>, printer's error, duplicate word in text, <a href="#tnd_16">'equalizeth the + Force and and Moment,'</a>.</p> + + <p>Page <a href="#Page_17">17</a><a name="tn_17a" id="tn_17a"></a>, printer's error, rhe for the, <a href="#tnd_17a">'as in rhe Stilliard,'</a>.</p> + + <p>Page <a href="#Page_17">17</a><a name="tn_17b" id="tn_17b"></a>, missing space between words, <a href="#tnd_17b">'asoften as that'</a>.</p> + + <p>Page <a href="#Page_18">18</a><a name="tn_18" id="tn_18"></a>, printer's error, specifiaclly for specifically, <a href="#tnd_18">'A Solid specifiaclly graver'</a>.</p> + + <p>Page <a href="#Page_20">20</a><a name="tn_20b" id="tn_20b"></a>, potential printer's error, properly for property, <a href="#tnd_20b">'but + this properly they have'</a>.</p> + + <p>Page <a href="#Page_20">20</a><a name="tn_20" id="tn_20"></a>, printer's error, n for u, <a href="#tnd_20">'loseth all a{u}thenticalness'</a>.</p> + + <p>Page <a href="#Page_22">22</a><a name="tn_22" id="tn_22"></a>, printer's error or variation in spelling, Benonamico for + Buonamico, <a href="#tnd_22">'it seemes that Benonamico'</a>.</p> + + <p>Page <a href="#Page_23">23</a><a name="tn_23" id="tn_23"></a>, printer's error, missing i, <a href="#tnd_23">'accordng to its excess'</a>.</p> + + <p>Page <a href="#Page_24">24</a><a name="tn_24" id="tn_24"></a>, missing line at the end of page in original text, <a href="#tnd_24">'its Region it loseth all'</a>.</p> + + <p>Page <a href="#Page_26">26</a><a name="tn_26" id="tn_26"></a>, missing letter n, <a href="#tnd_26">'u{n}able by its small weight'</a>.</p> + + <p>Page <a href="#Page_29">29</a><a name="tn_29" id="tn_29"></a>, missing letter e, <a href="#tnd_29">'that I have gon{e} about'</a>.</p> + + <p>Page <a href="#Page_32">32</a><a name="tn_32" id="tn_32"></a>, unclear symbol in original text, <a href="#tnd_32">'other Figure, {&}c.'</a>.</p> + + <p>Page <a href="#Page_37">37</a><a name="tn_37" id="tn_37"></a>, potential printer's error, comma in unusual position, + <a href="#tnd_37">'whatever Figure, goeth always'</a>.</p> + + <p>Page <a href="#Page_38">38</a><a name="tn_38" id="tn_38"></a>, missing space between words, <a href="#tnd_38">'Superficies might bedry:'</a>.</p> + + <p>Page <a href="#Page_39">39</a><a name="tn_39" id="tn_39"></a>, missing letter t, unied for united, <a href="#tnd_39">'which holds them unied,'</a>.</p> + + <p>Page <a href="#Page_41">41</a><a name="tn_41" id="tn_41"></a>, printer's error, Motitions for Motions, <a href="#tnd_41">'all Motitions are + made'</a>.</p> + + <p>Page <a href="#Page_42">42</a><a name="tn_42" id="tn_42"></a>, sidenote, possible missing letter e, <a href="#tnd_42">'Se{e} what satisfaction'</a>.</p> + + <p>Page <a href="#Page_43">43</a><a name="tn_43" id="tn_43"></a>, printer's error, Subdidivisions for Subdivisions, <a href="#tnd_43">'other + Subdidivisions,'</a>.</p> + + <p>Page <a href="#Page_49">49</a><a name="tn_49" id="tn_49"></a>, missing letter i, dminishing for diminishing, <a href="#tnd_49">'or dminishing + it by dividing'</a>.</p> + + <p>Page <a href="#Page_50">50</a><a name="tn_50" id="tn_50"></a>, sidenote, printer's error, missing letter l, hep for help, + <a href="#tnd_50">'float by hep of'</a>.</p> + + <p>Page <a href="#Page_53">53</a><a name="tn_53" id="tn_53"></a>, printer's error, missing letter n, beig for being, <a href="#tnd_53">'beig + double in Gravity'</a>.</p> + + <p>Page <a href="#Page_54">54</a><a name="tn_54" id="tn_54"></a>, printer's error, missing letter l, <a href="#tnd_54">'sha{l}l also descend.'</a>.</p> + + <p>Page <a href="#Page_55">55</a><a name="tn_55" id="tn_55"></a>, printer's error, missing letter r, <a href="#tnd_55">'to fo{r}m Solid Bodies,'</a>.</p> + + <p>Page <a href="#Page_56">56</a><a name="tn_56" id="tn_56"></a>, printer's error, missing letter A, <a href="#tnd_56">'Cone S {A} T'</a>.</p> + + <p>Page <a href="#Page_57">57</a><a name="tn_57" id="tn_57"></a>, printer's error, missing letter t, <a href="#tnd_57">'of which i{t} may + descend'</a>.</p> + + <p>Page <a href="#Page_58">58</a><a name="tn_58" id="tn_58"></a>, sidenote, printer's error, inverted n, <a href="#tnd_58">'Natatio{n} easiest + effected'</a>.</p> + + <p>Page <a href="#Page_59">59</a><a name="tn_59a" id="tn_59a"></a>, missing letter u, <a href="#tnd_59a">'witho{u}t all Question,'</a>.</p> + + <p>Page <a href="#Page_59">59</a><a name="tn_59b" id="tn_59b"></a>, printer's error, inverted n, <a href="#tnd_59b">'with an other Experime{n}t'</a>.</p> + + <p>Page <a href="#Page_59">59</a><a name="tn_59c" id="tn_59c"></a>, potential printer's error, sidenote ends with comma, <a href="#tnd_59c">'Or rather Contiguity,'</a>.</p> + + <p>Page <a href="#Page_61">61</a><a name="tn_61" id="tn_61"></a>, missing letter a, <a href="#tnd_61">'that in this c{a}se the water,'</a>.</p> + + <p>Page <a href="#Page_74">74</a><a name="tn_74" id="tn_74"></a>, printer's error, ir for it, <a href="#tnd_74">'but if we do saw ir,'</a>.</p> + + <p>Page <a href="#Page_75">75</a><a name="tn_75" id="tn_75"></a>, unclear symbol in original text, <a href="#tnd_75">'{&}c. making seven + Segments'</a>.</p> + +</div> + + + + + + + + + +<pre> + + + + + +End of Project Gutenberg's Discourse on Floating Bodies, by Galileo Galilei + +*** END OF THIS PROJECT GUTENBERG EBOOK DISCOURSE ON FLOATING BODIES *** + +***** This file should be named 37729-h.htm or 37729-h.zip ***** +This and all associated files of various formats will be found in: + https://www.gutenberg.org/3/7/7/2/37729/ + +Produced by Tim Madden and the Online Distributed +Proofreading Team at https://www.pgdp.net (This file was +produced from images generously made available by The +Internet Archive) + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. 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You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: Discourse on Floating Bodies + +Author: Galileo Galilei + +Translator: Thomas Salusbury + +Release Date: October 12, 2011 [EBook #37729] + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK DISCOURSE ON FLOATING BODIES *** + + + + +Produced by Tim Madden and the Online Distributed +Proofreading Team at https://www.pgdp.net (This file was +produced from images generously made available by The +Internet Archive) + + + + + + + [Transcriber's Notes + + All apparent printer's errors retained. Variation in punctuation are + as in the original, but missing full stops at end of paragraphs have + been supplied. There are inconsistencies in the use of italics, + spacing of words and use of full stop after 'AXIOME', abbreviations + etc. All are retained to match text. There is a great variation in + spelling including multiple spellings of the same word, all spelling + has been retained to match text. There are several instances of + obviously missing letters or inverted n & u. These have been changed + or obvious letters replaced, with the changes surrounded by {}. + + All instances are detailed at the end of the text. It should also be + noted that in the original text there is a missing line at the end of + page 24 in original text. + + There are a number of instances in the original text where 'that' is + immediately followed by a second 'that' in the sentence. These could + be potential printer's errors or, since several of them make sense, + part of the author's style. They have been left in the text as they + appear in the original text. + + The original text has many sidenotes, some are true sidenotes, + introductions to paragraphs etc, some acting as footnotes with some + marked in original text with *. These have been dealt with in three + ways with the footnotes placed after their relevant paragraph and + sidenotes place before their relevant paragraph. + + 1) Footnotes marked with capital letter. These were sidenotes in + original text marked with * in the original text and thus acting + like footnotes. + + 2) Footnotes marked with number. These were sidenotes in original + text that were unmarked but acting like normal footnotes. The anchor + in the text was placed at the most suitable relevant place in + comparison with the placement of the sidenote text in the margin, + but still should be considered only an approximate placement. + + 3) Sidenotes placed at start of the relevant paragraph. Some + sidenotes were considered not to be relevant as footnotes, + introductions to paragraphs etc, and were left as sidenotes before + their relevant paragraph.] + + * * * * * + + + + + A + DISCOURSE + _PRESENTED_ + TO THE MOST SERENE + Don Cosimo II. + GREAT DUKE + _OF_ + TUSCANY, + + CONCERNING + + The _NATATION_ of BODIES Vpon, + And _SUBMERSION_ In, + THE + WATER. + + By GALILEUS GALILEI: Philosopher and + Mathematician unto His most Serene Highnesse. + + Englished from the Second Edition of the ITALIAN, + compared with the Manuscript Copies, and reduced + into PROPOSITIONS: + + By _THOMAS SALUSBURY_, Esq; + + _LONDON_: + + Printed by WILLIAM LEYBOURN: + + _M DC LXIII._ + + * * * * * + + [Decoration] + + + + + A DISCOVRSE + + Presented to the Most Serene DON COSIMO II. + + GREAT DUKE of _TUSCANY_: + + CONCERNING + + _The Natation of BODIES Upon, or Submersion_ + _In, the WATER._ + + + + +Considering (Most Serene Prince) that the publishing this present +Treatise, of so different an Argument from that which many expect, and +which according to the intentions I proposed in my [A] Astronomicall +_Adviso_, I should before this time have put forth, might peradventure +make some thinke, either that I had wholly relinquished my farther +imployment about the new Celestiall Observations, or that, at least, I +handled them very remissely; I have judged fit to render an account, +aswell of my deferring that, as of my writing, and publishing this +treatise. + + [A] His Nuncio Siderio. + +As to the first, the last discoveries of _Saturn_ to be +tricorporeall, and of the mutations of Figure in _Venus_, like to +those that are seen in the Moon, together with the Consequents +depending thereupon, have not so much occasioned the demur, as the +investigation of the times of the Conversions of each of the Four +Medicean Planets about _Jupiter_, which I lighted upon in _April_ the +year past, 1611, at my being in _Rome_; where, in the end, I +assertained my selfe, that the first and neerest to _Jupiter_, moved +about 8 _gr._ & 29 _m._ of its Sphere in an houre, makeing its whole +revolution in one naturall day, and 18 hours, and almost an halfe. The +second moves in its Orbe 14 _gr._ 13 _min._ or very neer, in an hour, +and its compleat conversion is consummate in 3 dayes, 13 hours, and +one third, or thereabouts. The third passeth in an hour, 2 _gr._ 6 +_min._ little more or less of its Circle, and measures it all in 7 +dayes, 4 hours, or very neer. The fourth, and more remote than the +rest, goes in one houre, 0 _gr_ 54 _min._ and almost an halfe of its +Sphere, and finisheth it all in 16 dayes, and very neer 18 hours. But +because the excessive velocity of their returns or restitutions, +requires a most scrupulous precisenesse to calculate their places, in +times past and future, especially if the time be for many Moneths or +Years; I am therefore forced, with other Observations, and more exact +than the former, and in times more remote from one another, to correct +the Tables of such Motions, and limit them even to the shortest +moment: for such exactnesse my first Observations suffice not; not +only in regard of the short intervals of Time, but because I had not +as then found out a way to measure the distances between the said +Planets by any Instrument: I Observed such Intervals with simple +relation to the Diameter of the Body of _Jupiter_; taken, as we have +said, by the eye, the which, though they admit not errors of above a +Minute, yet they suffice not for the determination of the exact +greatness of the Spheres of those Stars. But now that I have hit upon +a way of taking such measures without failing, scarce in a very few +Seconds, I will continue the observation to the very occultation of +_JUPITER_, which shall serve to bring us to the perfect knowledge of +the Motions, and Magnitudes of the Orbes of the said Planets, together +also with some other consequences thence arising. I adde to these +things the observation of some obscure Spots[1], which are discovered in +the Solar Body, which changing, position in that, propounds to our +consideration a great argument either that the Sun revolves in it +selfe, or that perhaps other Starrs, in like manner as _Venus_ and +_Mercury_, revolve about it, invisible in other times, by reason of +their small digressions, lesse than that of _Mercury_, and only +visible when they interpose between the Sun and our eye, or else hint +the truth of both this and that; the certainty of which things ought +not to be contemned, nor omitted. + + [1] The Authors Observations of the Solar Spots + + _Continuall observation hath at last assured me that these Spots + are matters contiguous to the Body of the Sun, there continually + produced in great number, and afterwards dissolved, some in a + shorter, some in a longer time, and to be by the Conversion or + Revolution of the Sun in it selfe, which in a Lunar Moneth, or + thereabouts, finisheth its Period, caried about in a Circle, an + accident great of it selfe, and greater for its Consequences._ + +As to the other particular in the next place [B] Many causes have +moved me to write the present Tract, the subject whereof, is the +Dispute which I held some dayes since, with some learned men of this +City, about which, as your Highnesse knows, have followed many +Discourses: The principall of which Causes hath been the Intimation of +your Highnesse, having commended to me Writing, as a singular means to +make true known from false, reall from apparent Reasons, farr better +than by Disputing vocally, where the one or the other, or very often +both the Disputants, through too greate heate, or exalting of the +voyce, either are not understood, or else being transported by +ostentation of not yeilding to one another, farr from the first +Proposition, with the novelty, of the various Proposals, confound both +themselves and their Auditors. + + [B] The occasion inducing the Author to write this Treatise. + +Moreover, it seemed to me convenient to informe your Highnesse of all +the sequell, concerning the Controversie of which I treat, as it hath +been advertised often already by others: and because the Doctrine +which I follow, in the discussion of the point in hand, is different +from that of _Aristotle_; and interferes with his Principles, I have +considered that against the Authority of that most famous Man, which +amongst many makes all suspected that comes not from the Schooles of +the Peripateticks, its farr better to give ones Reasons by the Pen +than by word of mouth, and therfore I resolved to write the present +discourse: in which yet I hope to demonstrate that it was not out of +capritiousnesse, or for that I had not read or understood _Aristotle_, +that I sometimes swerve from his opinion, but because severall Reasons +perswade me to it, and the same _Aristotle_ hath tought me to fix my +judgment on that which is grounded upon Reason, and not on the bare +Authority of the Master[2]; and it is most certaine according to the +sentence of _Alcinoos_, that philosophating should be free. Nor is the +resolution of our Question in my judgment without some benefit to the +Universall[3], forasmuch as treating whether the figure of Solids +operates, or not, in their going, or not going to the bottome in +Water, in occurrences of building Bridges or other Fabricks on the +Water, which happen commonly in affairs of grand import, it may be of +great availe to know the truth. + + [2] _Aristotle_ prefers Reason to the Authority ofan Author. + + [3] The benefit of this Argument. + +I say therfore, that being the last Summer in company with certain +Learned men, it was said in the argumentation; That Condensation was +the propriety of Cold[4], and there was alledged for instance, the +example of Ice: now I at that time said, that, in my judgment, the Ice +should be rather Water rarified than condensed[5], and my reason was, +because Condensation begets diminution of Mass, and augmentation of +gravity, and Rarifaction causeth greater Lightness, and augmentarion +of Masse: and Water in freezing, encreaseth in Masse, and the Ice made +thereby is lighter than the Water on which it swimmeth. + + [4] Condensation the Propriety of Cold, according to the + Peripateticks. + + [5] Ice rather water rarified, than condensed, and why: + + _What I say, is manifest, because, the medium subtracting from the + whole Gravity of Sollids the weight of such another Masse of the + said Medium; as_ Archimedes _proves in his_ [C] First Booke De + Insidentibus Humido; _when ever the Masse of the said Solid + encreaseth by Distraction, the more shall the_ Medium _detract from + its entire Gravity; and lesse, when by Compression it shall be + condensed and reduced to a lesse Masse._ + + [C] In lib: 1. of Natation of Bodies Prop. 7. + + [Sidenote: Figure operates not in the Natation of Sollids.] + +It was answered me, tha{t} that proceeded not from the greater Levity, +but from the Figure, large and flat, which not being able to penetrate +the Resistance of the Water, is the cause that it submergeth not. I +replied, that any piece of Ice, of whatsoever Figure, swims upon the +Water, a manifest signe, that its being never so flat and broad, hath +not any part in its floating: and added, that it was a manifest proofe +hereof to see a piece of Ice of very broad Figure being thrust to the +botome of the Water, suddenly return to flote atoppe, which had it +been more grave, and had its swimming proceeded from its Forme, unable +to penetrate the Resistance of the _Medium_, that would be altogether +impossible; I concluded therefore, that the Figure was in sort a Cause +of the Natation or Submersion of Bodies, but the greater or lesse +Gravity in respect of the Water: and therefore all Bodyes heavier than +it of what Figure soever they be, indifferently go to the bottome, and +the lighter, though of any figure, float indifferently on the top: and +I suppose that those which hold otherwise, were induced to that +beliefe, by seeing how that diversity of Formes or Figures, greatly +altereth the Velosity, and Tardity of Motion; so that Bodies of Figure +broad and thin, descend far more leasurely into the Water, than those +of a more compacted Figure, though both made of the same Matter: by +which some might be induced to believe that the Dilatation of the +Figure might reduce it to such amplenesse that it should not only +retard but wholly impede and take away the Motion, which I hold to be +false. Upon this Conclusion, in many dayes discourse, was spoken much, +and many things, and divers Experiments produced, of which your +Highnesse heard, and saw some, and in this discourse shall have all +that which hath been produced against my Assertion, and what hath been +suggested to my thoughts on this matter, and for confirmation of my +Conclusion: which if it shall suffice to remove that (as I esteem +hitherto false) Opinion, I shall thinke I have not unprofitably spent +my paynes and time. and although that come not to passe, yet ought I +to promise another benefit to my selfe, namely, of attaining the +knowledge of the truth, by hearing my Fallacyes confuted, and true +demonstrations produced by those of the contrary opinion. + +And to proceed with the greatest plainness and perspicuity that I can +possible, it is, I conceive, necessary, first of all to declare what +is the true, intrinsecall, and totall Cause, of the ascending of some +Sollid Bodyes in the Water, and therein floating; or on the contrary, +of their sinking and so much the rather in asmuch as I cannot satisfie +myselfe in that which _Aristotle_ hath left written on this Subject. + + [Sidenote: The cause of the Natation & submersion of Solids in + the Water.] + +I say then the Cause why some Sollid Bodyes descend to the Bottom of +Water, is the excesse of their Gravity, above the Gravity of the +Water; and on the contrary, the excess of the Waters Gravity above the +Gravity of those, is the Cause that others do not descend, rather that +they rise from the Bottom, and ascend to the Surface. This was +subtilly demonstrated by _Archimedes_ in his Book Of the NATATION of +BODIES: Conferred afterwards by a very grave Author, but, if I erre +not invisibly, as below for defence of him, I shall endeavour to +prove. + +I, with a different Method, and by other meanes, will endeavour to +demonstrate the same, reducing the Causes of such Effects to more +intrinsecall and immediate Principles, in which also are discovered +the Causes of some admirable and almost incredible Accidents, as that +would be, that a very little quantity of Water, should be able, with +its small weight, to raise and sustain a Solid Body, an hundred or a +thousand times heavier than it. + +And because demonstrative Order so requires, I shall define certain +Termes, and afterwards explain some Propositions, of which, as of +things true and obvious, I may make use of to my present purpose. + + + + +DEFINITION I. + + _I then call equally Grave_ in specie, _those Matters of which equall + Masses weigh equally._ + + +As if for example, two Balls, one of Wax, and the other of some Wood +of equall Masse, were also equall in Weight, we say, that such Wood, +and the Wax are _in specie_ equally grave. + + + + +DEFINITION II. + + _But equally grave in Absolute Gravity, we call two Sollids, + weighing equally, though of Mass they be unequall._ + + +As for example, a Mass of Lead, and another of Wood, that weigh each +ten pounds, I call equall in Absolute Gravity, though the Mass of the +Wood be much greater then that of the Lead. + +_And, consequently, less Grave_ in specie. + + + + +DEFINITION III. + + _I call a Matter more Grave_ in specie _than another, of which a + Mass, equall to a Mass of the other, shall weigh more._ + + +And so I say, that Lead is more grave _in specie_ than Tinn, because +if you take of them two equall Masses, that of the Lead weigheth more. + + + + +DEFINITION IV. + + _But I call that Body more grave absolutely than this, if that + weigh more than this, without any respect had to the Masses._ + + +And thus a great piece of Wood is said to weigh more than a little +lump of Lead, though the Lead be _in specie_ more heavy than the Wood. +And the same is to be understood of the less grave _in specie_, and +the less grave absolutely. + +These Termes defined, I take from the Mechanicks two Principles: the +first is, that + + + + +AXIOME. I. + + _Weights absolutely equall, moved with equall Velocity, are of + equall Force and Moment in their operations._ + + + + +_DEFINITION V._ + + Moment, amongst Mechanicians, signifieth that Vertue, that Force, + or that Efficacy, with which the Mover moves, and the Moveable + resists. + + + _Which Vertue dependes not only on the simple Gravity, but on the + Velocity of the Motion, and on the diverse Inclinations of the + Spaces along which the Motion is made: For a descending Weight + makes a greater Impetus in a Space much declining, than in one less + declining; and in summe, what ever is the occasion of such Vertue, + it ever retaines the name of Moment; nor in my Judgement, is this + sence new in our Idiome, for, if I mistake not, I think we often + say; This is a weighty businesse, but the other is of small moment: + and we consider lighter matters and let pass those of Moment; a + Metaphor, I suppose, taken from the Mechanicks._ + +As for example, two weights equall in absolute Gravity, being put +into a Ballance of equall Arms, they stand in _Equilibrium_, neither +one going down, nor the other up: because the equality of the +Distances of both, from the Centre on which the Ballance is supported, +and about which it moves, causeth that those weights, the said +Ballance moving, shall in the same Time move equall Spaces, that is, +shall move with equall Velocity, so that there is no reason for which +this Weight should descend more than that, or that more than this; and +therefore they make an _Equilibrium_, and their Moments continue of +semblable and equall Vertue. + +The second Principle is; That + + + + +AXIOME II. + + _The Moment and Force of the Gravity, is encreased by the Velocity + of the Motion._ + + +So that Weights absolutely equall, but conjoyned with Velocity +unequall, are of Force, Moment and Vertue unequall: and the more +potent, the more swift, according to the proportion of the Velocity of +the one, to the Velocity of the other. Of this we have a very +pertinent example in the Balance or Stiliard of unequall Arms, at +which Weights absolutely equall being suspended, they do not weigh +down, and gravitate equally, but that which is at a greater distance +from the Centre, about which the Beam moves, descends, raising the +other, and the Motion of this which ascends is slow, and the other +swift: and such is the Force and Vertue, which from the Velocity of +the Mover, is conferred on the Moveable, which receives it, that it +can exquisitely compensate, as much more Weight added to the other +slower Moveable: so that if of the Arms of the Balance, one were ten +times as long as the other, whereupon in the Beames moving about the +Centre, the end of that would go ten times as far as the end of this, +a Weight suspended at the greater distance, may sustain and poyse +another ten times more grave absolutely than it: and that because the +Stiliard moving, the lesser Weight shall move ten times faster than +the bigger. It ought alwayes therefore to be understood, that Motions +are according to the same Inclinations, namely, that if one of the +Moveables move perpendicularly to the Horizon, then the other makes +its Motion by the like Perpendicular; and if the Motion of one were to +be made Horizontally; that then the other is made along the same +Horizontall plain: and in summe, alwayes both in like Inclinations. +This proportion between the Gravity and Velocity is found in all +Mechanicall Instruments: and is considered by _Aristotle_, as a +Principle in his _Mechanicall Questions_; whereupon we also may take +it for a true Assumption, That + + + + +AXIOME III. + + _Weights absolutely unequall, do alternately counterpoyse and + become of equall Moments, as oft as their Gravities, with + contrary proportion, answer to the Velocity of their Motions._ + + +That is to say, that by how much the one is less grave than the other, +by so much is it in a constitution of moving more swiftly than that. + +Having prefatically explicated these things, we may begin to enquire, +what Bodyes those are which totally submerge in Water, and go to the +Bottom, and which those that by constraint float on the top, so that +being thrust by violence under Water, they return to swim, with one +part of their Mass visible above the Surface of the Water: and this we +will do by considering the respective operation of the said Solids, +and of Water: Which operation followes the Submersion and sinking; and +this it is[6], That in the Submersion that the Solid maketh, being +depressed downwards by its proper Gravity, it comes to drive away the +water from the place where it successively subenters, and the water +repulsed riseth and ascends above its first levell, to which Ascent on +the other side it, as being a grave Body of its own nature, resists: +And because the descending Solid more and more immerging, greater and +greater quantity of Water ascends, till the whole Sollid be submerged; +its necessary to compare the Moments of the Resistance of the water to +Ascension, with the Moments of the pressive Gravity of the Solid: And +if the Moments of the Resistance of the water, shall equalize the +Moments of the Solid, before its totall Immersion[7]; in this case +doubtless there shall be made an _Equilibrium_, nor shall the Body +sink any farther. But if the Moment of the Solid, shall alwayes exceed +the Moments wherewith the repulsed water successively makes +Resistance[8], that Solid shall not only wholly submerge under water, but +shall descend to the Bottom. But if, lastly, in the instant of totall +Submersion, the equality shall be made between the Moments of the +prement Solid, and the resisting Water[9]; then shall rest, ensue, and +the said Solid shall be able to rest indifferently, in whatsoever part +of the water. By this time is manifest the necessity of comparing the +Gravity of the water, and of the Solid[10]; and this comparison might at +first sight seem sufficient to conclude and determine which are the +Solids that float a-top, and which those that sink to the Bottom in +the water, asserting that those shall float which are lesse grave _in +specie_ than the water, and those submerge, which are _in specie_ more +grave. For it seems in appearance, that the Sollid in sinking +continually, raiseth so much Water in Mass, as answers to the parts of +its own Bulk submerged: whereupon it is impossible, that a Solid less +grave _in specie_, than water, should wholly sink, as being unable to +raise a weight greater than its own, and such would a Mass of water +equall to its own Mass be. And likewise it seems necessary, that the +graver Solids do go to the Bottom, as being of a Force more than +sufficient for the raising a Masse of water, equall to its own, though +inferiour in weight. Nevertheless the business succeeds otherwise: and +though the Conclusions are true, yet are the Causes thus assigned +deficient, nor is it true, that the Solid in submerging, raiseth and +repulseth Masses of Water, equall to the parts of it self submerged; +but the Water repulsed, is alwayes less than the parts of the Solid +submerged[11]: and so much the more by how much the Vessell in which the +Water is contained is narrower: in such manner that it hinders not, +but that a Solid may submerge all under Water, without raising so much +Water in Mass, as would equall the tenth or twentieth part of its own +Bulk: like as on the contrary, a very small quantity of Water, may +raise a very great Solid Mass[12], though such Solid should weigh +absolutely a hundred times as much, or more, than the said Water, if +so be that the Matter of that same Solid be _in specie_ less grave +than the Water. And thus a great Beam, as suppose of a 1000 weight, +may be raised and born afloat by Water, which weighs not 50: and this +happens when the Moment of the Water is compensated by the Velocity of +its Motion. + + [6] How the submersion of Solids in the Water, is effected. + + [7] What Solids shall float on the Water. + + [8] What Solids shall sinke to the botome. + + [9] What Solids shall rest in all places of the Water. + + [10] The Gravitie of the Water and Solid must be compared in all + Problems, of Natation of Bodies. + + [11] The water repelled is ever less than the parts of the Sollid + submerged. + + [12] _A_ small quantity of water, may float a very great Solid + Mass. + +But because such things, propounded thus in abstract, are somewhat +difficult to be comprehended, it would be good to demonstrate them by +particular examples; and for facility of demonstration, we will +suppose the Vessels in which we are to put the Water, and place the +Solids, to be inviron'd and included with sides erected perpendicular +to the Plane of the Horizon, and the Solid that is to be put into such +vessell to be either a streight Cylinder, or else an upright Prisme. + +_The which proposed and declared, I proceed to demonstrate the truth +of what hath been hinted, forming the ensuing Theoreme._ + + + + +_THEOREME I._ + + [Sidenote: The Proportion of the water raised to the Solid + submerged.] + + The Mass of the Water which ascends in the submerging of a Solid, + Prisme or Cylinder, or that abaseth in taking it out, is less + than the Mass of the said Solid, so depressed or advanced: and + hath to it the same proportion, that the Surface of the Water + circumfusing the Solid, hath to the same circumfused Surface, + together with the Base of the Solid. + + +_Let the Vessell be A B C D, and in it the Water raised up to the +Levell E F G, before the Solid Prisme H I K be therein immerged; but +after that it is depressed under Water, let the Water be raised as +high as the Levell L M, the Solid H I K shall then be all under Water, +and the Mass of the elevated Water shall be L G, which is less than +the Masse of the Solid depressed, namely of H I K, being equall to the +only part E I K, which is contained under the first Levell E F G. +Which is manifest, because if the Solid H I K be taken out, the Water +I G shall return into the place occupied by the Mass E I K, where it +was continuate before the submersion of the Prisme. And the Mass L G +being equall to the Mass E K: adde thereto the Mass E N, and it shall +be the whole Mass E M, composed of the parts of the Prisme E N, and of +the Water N F, equall to the whole Solid H I K: And, therefore, the +Mass L G shall have the same proportion to E M, as to the Mass H I K: +But the Mass L G hath the same proportion to the Mass E M, as the +Surface L M hath to the Surface M H: Therefore it is manifest, that +the Mass of Water repulsed L G, is in proportion to the Mass of the +Solid submerged H I K; as the Surface L M, namely, that of the Water +ambient about the Sollid, to the whole Surface H M, compounded of the +said ambient water, and the Base of the Prisme H N. But if we suppose +the first Levell of the Water the according to the Surface H M, and +the Prisme allready submerged H I K; and after to be taken out and +raised to E A O, and the Water to be faln from the first Levell H L M +as low as E F G; It is manifest, that the Prisme E A O being the same +with H I K, its superiour part H O, shall be equall to the inferiour E +I K: and remove the common part E N, and, consequently, the Mass of +the Water L G is equall to the Mass H O; and, therefore, less than the +Solid, which is without the Water, namely, the whole Prisme E A O, to +which likewise, the said Mass of Water abated L G, hath the same +proportion, that the Surface of the Waters circumfused L M hath to the +same circumfused Surface, together with the Base of the Prisme A O: +which hath the same demonstration with the former case above._ + +[Illustration] + +_And from hence is inferred, that the Mass of the Water, that riseth +in the immersion of the Solid, or that ebbeth in elevating it, is not +equall to all the Mass of the Solid, which is submerged or elevated, +but to that part only, which in the immersion is under the first +Levell of the Water, and in the elevation remaines above the first +Levell: Which is that which was to be demonstrated. We will now pursue +the things that remain._ + +And first we will demonstrate that, + + + + +THEOREME II. + + [Sidenote: The proportion of the water abated, to the Solid + raised.] + + _When in one of the above said Vessels, of what ever breadth, + whether wide or narrow, there is placed such a Prisme or + Cylinder, inviron'd with Water, if we elevate that Solid + perpendicularly, the Water circumfused shall abate, and the + Abatement of the Water, shall have the same proportion to the + Elevation of the Prisme, as one of the Bases of the Prisme, hath + to the Surface of the Water Circumfused._ + + +[Illustration] + +Imagine in the Vessell, as is aforesaid, the Prisme A C D B to be +placed, and in the rest of the Space the Water to be diffused as far +as the Levell E A: and raising the Solid, let it be transferred to G +M, and let the Water be abased from E A to N O: I say, that the +descent of the Water, measured by the Line A O, hath the same +proportion to the rise of the Prisme, measured by the Line G A, as the +Base of the Solid G H hath to the Surface of the Water N O. The which +is manifest: because the Mass of the Solid G A B H, raised above the +first Levell E A B, is equall to the Mass of Water that is abased E N +O A. Therefore, E N O A and G A B H are two equall Prismes; for of +equall Prismes, the Bases answer contrarily to their heights: +Therefore, as the Altitude A O is to the Altitude A G, so is the +Superficies or Base G H to the Surface of the Water N O. If therefore, +for example, a Pillar were erected in a waste Pond full of Water, or +else in a Well, capable of little more then the Mass of the said +Pillar, in elevating the said Pillar, and taking it out of the Water, +according as it riseth, the Water that invirons it will gradually +abate, and the abasement of the Water at the instant of lifting out +the Pillar, shall have the same proportion, that the thickness of the +Pillar hath to the excess of the breadth of the said Pond or Well, +above the thickness of the said Pillar: so that if the breadth of the +Well were an eighth part larger than the thickness of the Pillar, and +the breadth of the Pond twenty five times as great as the said +thickness, in the Pillars ascending one foot, the water in the Well +shall descend seven foot, and that in the Pond only 1/25 of a foot. + + [Sidenote: Why a Solid less grave _in specie_ than water, stayeth + not under water, in very small depths:] + +This Demonstrated, it will not be difficult to show the true cause, +how it comes to pass, that, + + + + +THEOREME III. + + _A Prisme or regular Cylinder, of a substance specifically less + grave than Water, if it should be totally submerged in Water, + stayes not underneath, but riseth, though the Water circumfused + be very little, and in absolute Gravity, never so much inferiour + to the Gravity of the said Prisme._ + + +Let then the Prisme A E F B, be put into the Vessell C D F B, the same +being less grave _in specie_ than the Water: and let the Water infused +rise to the height of the Prisme: I say, that the Prisme left at +liberty, it shall rise, being born up by the Water circumfused C D E +A. For the Water C E being specifically more grave than the Solid A F, +the absolute weight of the water C E, shall have greater proportion to +the absolute weight of the Prisme A F, than the Mass C E hath to the +Mass A F (in regard the Mass hath the same proportion to the Mass, +that the weight absolute hath to the weight absolute, in case the +Masses are of the same Gravity _in specie_.) But the Mass C E is to +the Mass A F, as the Surface of the water A C, is to the Superficies, +or Base of the Prisme A B; which is the same proportion as the ascent +of the Prisme when it riseth, hath to the descent of the Water +circumfused C E. + +[Illustration] + +Therefore, the absolute Gravity of the water C E, hath greater +proportion to the absolute Gravity of the Prisme A F; than the Ascent +of the Prisme A F, hath to the descent of the said water C E. The +Moment, therefore, compounded of the absolute Gravity of the water C +E, and of the Velocity of its descent, whilst it forceably repulseth +and raiseth the Solid A F, is greater than the Moment compounded of +the absolute Gravity of the Prisme A F, and of the Tardity of its +ascent, with which Moment it contrasts and resists the repulse and +violence done it by the Moment of the water: Therefore, the Prisme +shall be raised. + + [Sidenote: The Proportion according to which the Submersion & + Natation of Solids is made.] + +It followes, now, that we proceed forward to demonstrate more +particularly, how much such Solids shall be inferiour in Gravity to +the water elevated; namely, what part of them shall rest submerged, +and what shall be visible above the Surface of the water: but first it +is necessary to demonstrate the subsequent Lemma. + + + + +LEMMA I. + + [Sidenote: The absolute Gravity of Solids, are in a proportion + compounded of their Specifick Gravities, and of their Masses.] + + _The absolute Gravities of Solids, have a proportion compounded of + the proportions of their specificall Gravities, and of their + Masses._ + + +[Illustration] + +Let A and B be two Solids. I say, that the Absolute Gravity of A, +hath to the Absolute Gravity of B, a proportion compounded of the +proportions of the specificall Gravity of A, to the Specificall +Gravity of B, and of the Mass A to the Mass B. Let the Line D have the +same proportion to E, that the specifick Gravity of A, hath to the +specifick Gravity of B; and let E be to F, as the Mass A to the Mass +B: It is manifest, that the proportion of D to F, is compounded of the +proportions D and E; and E and F. It is requisite, therefore, to +demonstrate, that as D is to F, so the absolute Gravity of A, is to +the absolute Gravity of B. Take the Solid C, equall in Mass to the +Solid A, and of the same Gravity _in specie_ with the Solid B. +Because, therefore, A and C are equall in Mass, the absolute Gravity +of A, shall have to the absolute Gravity of C, the same proportion, as +the specificall Gravity of A, hath to the specificall Gravity of C, or +of B, which is the same _in specie_; that is, as D is to E. And, +because, C and B are of the same Gravity _in specie_, it shall be, +that as the absolute weight of C, is to the absolute weight of B, so +the Mass C, or the Mass A, is to the Mass B; that is, as the Line E to +the Line F. As therefore, the absolute Gravity of A, is to the +absolute Gravity of C, so is the Line D to the Line E: and, as the +absolute Gravity of C, is to the absolute Gravity of B, so is the Line +E to the Line F: Therefore, by Equality of proportion, the absolute +Gravity of A, is to the absolute Gravity of B, as the Line D to the +Line F: which was to be demonstrated. I proceed now to demonstrate, +how that, + + + + +THEOREME IV. + + [Sidenote: The proportion of water requisite to make a Solid + swim:] + + _If a Solid, Cylinder, or Prisme, lesse grave specifically than the + Water, being put into a Vessel, as above, of whatsoever + greatnesse, and the Water, be afterwards infused, the Solid shall + rest in the bottom, unraised, till the Water arrive to that part + of the Altitude, of the said Prisme, to which its whole Altitude + hath the same proportion, that the Specificall Gravity of the + Water, hath to the Specificall Gravity of the said Solid: but + infusing more Water, the Solid shall ascend._ + + +[Illustration] + +Let the Vessell be M L G N of any bigness, and let there be placed in +it the Solid Prisme D F G E, less grave _in specie_ than the water; +and look what proportion the Specificall Gravity of the water, hath to +that of the Prisme, such let the Altitude D F, have to the Altitude F +B. I say, that infusing water to the Altitude F B, the Solid D G shall +not float, but shall stand in _Equilibrium_, so, that that every +little quantity of water, that is infused, shall raise it. Let the +water, therefore, be infused to the Levell A B C; and; because the +Specifick Gravity of the Solid D G, is to the Specifick Gravity of the +water, as the altitude B F is to the altitude F D; that is, as the +Mass B G to the Mass G D; as the proportion of the Mass B G is to the +Mass G D, as the proportion of the Mass G D is to the Mass A F, they +compose the Proportion of the Mass B G to the Mass A F. Therefore, the +Mass B G is to the Mass A F, in a proportion compounded of the +proportions of the Specifick Gravity of the Solid G D, to the +Specifick Gravity of the water, and of the Mass G D to the Mass A F: +But the same proportions of the Specifick Gravity of G D, to the +Specifick Gravity of the water, and of the Mass G D to the Mass A F, +do also by the precedent _Lemma_, compound the proportion of the +absolute Gravity of the Solid D G, to the absolute Gravity of the Mass +of the water A F: Therefore, as the Mass B G is to the Mass A F, so is +the Absolute Gravity of the Solid D G, to the Absolute Gravity of the +Mass of the water A F. But as the Mass B G is to the Mass A F; so is +the Base of the Prisme D E, to the Surface of the water A B; and so is +the descent of the water A B, to the Elevation of the Prisme D G; +Therefore, the descent of the water is to the elevation of the Prisme, +as the absolute Gravity of the Prisme, is to the absolute Gravity of +the water: Therefore, the Moment resulting from the absolute Gravity +of the water A F, and the Velocity of the Motion of declination, with +which Moment it forceth the Prisme D G, to rise and ascend, is equall +to the Moment that results from the absolute Gravity of the Prisme D +G, and from the Velocity of the Motion, wherewith being raised, it +would ascend: with which Moment it resists its being raised: because, +therefore, such Moments are equall, there shall be an _Equilibrium_ +between the water and the Solid. And, it is manifest, that putting a +little more water unto the other A F, it will increase the Gravity and +Moment, whereupon the Prisme D G, shall be overcome, and elevated till +that the only part B F remaines submerged. Which is that that was to +be demonstrated. + + +COROLLARY I. + + [Sidenote: _H_ow far Solids less grave _in specie_ than water, do + submerge.] + + _By what hath been demonstrated, it is manifest, that Solids less + grave_ in specie _than the water, submerge only so far, that as + much water in Mass, as is the part of the Solid submerged, doth + weigh absolutely as much as the whole Solid._ + +For, it being supposed, that the Specificall Gravity of the water, is +to the Specificall Gravity of the Prisme D G, as the Altitude D F, is +to the Altitude F B; that is, as the Solid D G is to the Solid B G; we +might easily demonstrate, that as much water in Mass as is equall to +the Solid B G, doth weigh absolutely as much as the whole Solid D G; +For, by the _Lemma_ foregoing, the Absolute Gravity of a Mass of +water, equall to the Mass B G, hath to the Absolute Gravity of the +Prisme D G, a proportion compounded of the proportions, of the Mass B +G to the Mass G D, and of the Specifick Gravit{y} of the water, to the +Specifick Gravity of the Prisme: But the Gravity _in specie_ of the +water, to the Gravity _in specie_ of the Prisme, is supposed to be as +the Mass G D to the Mass G B. Therefore, the Absolute Gravity of a +Mass of water, equall to the Mass B G, is to the Absolute Gravity of +the Solid D G, in a proportion compounded of the proportions, of the +Mass B G to the Mass G D, and of the Mass D G to the Mass G B; which +is a proportion of equalitie. The Absolute Gravity, therefore, of a +Mass of Water equall to the part of the Mass of the Prisme B G, is +equall to the Absolute Gravity of the whole Solid D G. + + +COROLLARY II. + + [Sidenote: _A_ Rule to equilibrate Solids in the water.] + + _It followes, moreover, that a Solid less grave than the water, + being put into a Vessell of any imaginable greatness, and water + being circumfused about it to such a height, that as much water + in Mass, as is the part of the Solid submerged, do weigh + absolutely as much as the whole Solid; it shall by that water be + justly sustained, be the circumfused Water in quantity greater or + lesser._ + +[Illustration] + +For, if the Cylinder or Prisme M, less grave than the water, _v. gra._ +in Subsequiteriall proportion, shall be put into the capacious Vessell +A B C D, and the water raised about it, to three quarters of its +height, namely, to its Levell A D: it shall be sustained and exactly +poysed in _Equilibrium_. The same will happen; if the Vessell E N S F +were very small, so, that between the Vessell and the Solid M, there +were but a very narrow space, and only capable of so much water, as +the hundredth part of the Mass M, by which it should be likewise +raised and erected, as before it had been elevated to three fourths of +the height of the Solid: which to many at the first sight, may seem a +notable Paradox, and beget a conceit, that the Demonstration of these +effects, were sophisticall and fallacious: but, for those who so +repute it, the Experiment is a means that may fully satisfie them. But +he that shall but comprehend of what Importance Velocity of Motion is, +and how it exactly compensates the defect and want of Gravity, will +cease to wonder, in considering that at the elevation of the Solid M, +the great Mass of water A B C D abateth very little, but the little +Mass of water E N S F decreaseth very much, and in an instant, as the +Solid M before did rise, howbeit for a very short space: Whereupon the +Moment, compounded of the small Absolute Gravity of the water E N S F, +and of its great Velocity in ebbing, equalizeth the Force and and +Moment, that results from the composition of the immense Gravity of +the water A B C D, with its great slownesse of ebbing; since that in +the Elevation of the Sollid M, the abasement of the lesser water E S, +is performed just so much more swiftly than the great Mass of water A +C, as this is more in Mass than that which we thus demonstrate. + + [Sidenote: _T_he proportion according to which water riseth and + falls in different Vessels at the Immersion and Elevation of + Solids.] + +In the rising of the Solid M, its elevation hath the same proportion +to the circumfused water E N S F, that the Surface of the said water, +hath to the Superficies or Base of the said Solid M; which Base hath +the same proportion to the Surface of the water A D, that the +abasement or ebbing of the water A C, hath to the rise or elevation of +the said Solid M. Therefore, by Perturbation of proportion, in the +ascent of the said Solid M, the abasement of the water A B C D, to the +abasement of the water E N S F, hath the same proportion, that the +Surface of the water E F, hath to the Surface of the water A D; that +is, that the whole Mass of the water E N S F, hath to the whole Mass A +B C D, being equally high: It is manifest, therefore, that in the +expulsion and elevation of the Solid M, the water E N S F shall exceed +in Velocity of _M_otion the water A B C D, asmuch as it on the other +side is exceeded by that in quantity: whereupon their Moments in such +operations, are mutually equall. + +[Illustration] + + _And, for ampler confirmation, and clearer explication of this, let + us consider the present Figure, (which if I be not deceived, may + serve to detect the errors of some Practick Mechanitians who upon a + false foundation some times attempt impossible enterprizes,) in + which, unto the large Vessell E I D F, the narrow Funnell or Pipe I + C A B is continued, and suppose water infused into them, unto the + Levell L G H, which water shall rest in this position, not without + admiration in some, who cannot conceive how it can be, that the + heavie charge of the great Mass of water G D, pressing downwards, + should not elevate and repulse the little quantity of the other, + contained in the Funnell or Pipe C L, by which the descent of it is + resisted and hindered: But such wonder shall cease, if we begin to + suppose the water G D to be abased only to Q D, and shall + afterwards consider, what the water C L hath done, which to give + place to the other, which is descended from the Levell G H, to the + Levell Q O, shall of necessity have ascended in the same time, from + the Levell L unto A B. And the ascent L B, shall be so much greater + than the descent G Q, by how much the breadth of the Vessell G D, + is greater than that of the Funnell I C; which, in summe, is as + much as the water G D, is more than the water L C: but in regard + that the Moment of the Velocity of the Motion, in one Moveable, + compensates that of the Gravity of another what wonder is it, if + the swift ascent of the lesser Water C L, shall resist the slow + descent of the greater G D?_ + +The same, therefore, happens in this operation, as in rhe Stilliard, +in which a weight of two pounds counterpoyseth an other of 200, +asoften as that shall move in the same time, a space 100 times greater +than this: which falleth out when one Arme of the Beam is an hundred +times as long as the other. Let the erroneous opinion of those +therefore cease, who hold that a Ship is better, and easier born up in +a great abundance of water, then in a lesser quantity[13], (_this was +believed by_ Aristotle _in his Problems, Sect. 23, Probl. 2._) it being +on the contrary true, that its possible, that a Ship may as well float +in ten Tun of water, as in an Ocean. + + [13] A ship flotes as well in ten Tun of Water as in an Ocean. + + [Sidenote: A Solid specifiaclly graver than the water, cannot be + born up by any quantity of it.] + +But following our matter, I say, that by what hath been hitherto +demonstrated, we may understand how, that + + +COROLLARY III. + + _One of the above named Solids, when more grave_ in specie _than the + water, can never be sustained, by any whatever quantity of it._ + +For having seen how that the Moment wherewith such a Solid, as grave +_in specie_ as the water, contrasts with the Moment of any Mass of +water whatsoever, is able to retain it, even to its totall Submersion, +without its ever ascending; it remaineth, manifest, that the water is +far less able to raise it up, when it exceeds the same _in specie_: +so, that though you infuse water till its totall Submersion, it shall +still stay at the Bottome, and with such Gravity, and Resistance to +Elevation, as is the excess of its Absolute Gravity, above the +Absolute Gravity of a Mass equall to it, made of water, or of a Matter +_in specie_ equally grave with the water: and, though you should +moreover adde never so much water above the Levell of that which +equalizeth the Altitude of the Solid, it shall not, for all that, +encrease the Pression, or Gravitation, of the parts circumfused about +the said Solid, by which greater pression, it might come to be +repulsed; because, the Resistance is not made, but only by those parts +of the water, which at the Motion of the said Solid do also move, and +these are those only, which are comprehended by the two Superficies +equidistant to the Horizon, and their parallels, that comprehend the +Altitude of the Solid immerged in the water. + +I conceive, I have by this time sufficiently declared and opened the +way to the contemplation of the true, intrinsecall and proper Causes +of diverse Motions, and of the Rest of many Solid Bodies in diverse +_Mediums_, and particularly in the water, shewing how all in effect, +depend on the mutuall excesses of the Gravity of the Moveables and of +the _Mediums_: and, that which did highly import, removing the +Objection, which peradventure would have begotten much doubting, and +scruple in some, about the verity of my Conclusion, namely, how that +notwithstanding, that the excess of the Gravity of the water, above +the Gravity of the Solid, demitted into it, be the cause of its +floating and rising from the Bottom to the Surface, yet a quantity of +water, that weighs not ten pounds, can raise a Solid that weighs above +100 pounds: in that we have demonstrated, That it sufficeth, that such +difference be found between the Specificall Gravities of the _Mediums_ +and Moveables, let the particular and absolute Gravities be what they +will: insomuch, that a Solid, provided that it be Specifically less +grave than the water, although its absolute weight were 1000 pounds, +yet may it be born up and elevated by ten pounds of water, and less: +and on the contrary, another Solid, so that it be Specifically more +grave than the water, though in absolute Gravity it were not above a +pound, yet all the water in the Sea, cannot raise it from the Bottom, +or float it. This sufficeth me, for my present occasion, to have, by +the above declared Examples, discovered and demonstrated, without +extending such matters farther, and, as I might have done, into a long +Treatise: yea, but that there was a necessity of resolving the above +proposed doubt, I should have contented my self with that only, which +is demonstrated by _Archimedes_, in his first _Book De Insidentibus +humido_[14]: where in generall termes he infers and confirms the same +Conclusions, namely, that Solids (_a_) less grave than water, swim or +float upon it, the (_b_) more grave go to the Bottom, and the (_c_) +equally grave rest indifferently in all places, yea, though they +should be wholly under water. + + [14] _Of Natation_ (a) _Lib. 1, Prop. 4._ (b) _Id. Lib. 1. Prop. + 3._ (c) _Id. Lib. 1. Prop. 3._ + + [Sidenote: The Authors defence of _Archimedes_ his Doctrine, + against the oppositions of _Buonamico_.] + +But, because that this Doctrine of Archimedes, perused, transcribed +and examined by _Signor Francesco Buonamico_, in his _fifth Book of +Motion, Chap. 29_, and afterwards by him confuted, might by the +Authority of so renowned, and famous a Philosopher, be rendered +dubious, and suspected of falsity; I have judged it necessary to +defend it, if I am able so to do, and to clear _Archimedes_, from +those censures, with which he appeareth to be charged. _Buonamico_ +rejecteth the Doctrine of _Archimedes_, first[15], as not consentaneous +with the Opinion of _Aristotle_, adding, that it was a strange thing +to him, that the Water should exceed the Earth in Gravity[16], seeing on +the contrary, that the Gravity of water, increaseth, by means of the +participation of Earth. And he subjoyns presently after[17], that he was +not satisfied with the Reasons of _Archimedes_, as not being able with +that Doctrine, to assign the cause whence it comes, that a Boat and a +Vessell, which otherwise, floats above the water, doth sink to the +Bottom, if once it be filled with water; that by reason of the +equality of Gravity, between the water within it, and the other water +without, it should stay a top; but yet, nevertheless, we see it to go +to the Bottom. + + [15] His first Objection against the Doctrine of _Archimedes_. + + [16] His Second Objection. + + [17] His third Objection. + +He farther addes[18], that _Aristotle_ had clearly confuted the Ancients, +who said, that light Bodies moved upwards[19], driven by the impulse of +the more grave Ambient: which if it were so, it should seem of +necessity to follow, that all naturall Bodies are by nature heavy, and +none light: For that the same would befall the Fire and Air, if put in +the Bottom of the water. And, howbeit, _Aristotle_ grants a Pulsion in +the Elements, by which the Earth is reduced into a Sphericall Figure, +yet nevertheless, in his judgement; it is not such that it can remove +grave Bodies from their naturall places, but rather, that it send them +toward the Centre, to which (as he somewhat obscurely continues to +say,) the water principally moves, if it in the interim meet not with +something that resists it, and, by its Gravity, thrusts it out of its +place: in which case, if it cannot directly, yet at least as well as +it can, it tends to the Centre: but it happens, that light Bodies by +such Impulsion, do all ascend upward: but this properly they have by +nature, as also, that other of swimming. He concludes, lastly[20], that he +concurs with _Archimedes_ in his Conclusions; but not in the Causes, +which he would referre to the facile and difficult Separation of the +_Medium_, and to the predominance of the Elements, so that when the +Moveable superates the power of the _Medium_; as for example, Lead +doth the Continuity of water, it shall move thorow it, else not. + + [18] His fourth Objection. + + [19] The _A_ncients denyed _A_bsolute Levity. + + [20] The causes of Natation & Submersion, according to the + Peripateticks. + +This is all that I have been able to collect, as produced against +_Archimedes_ by _Signor Buonamico_: who hath not well observed the +Principles and Suppositions of _Archimedes_; which yet must be false, +if the Doctrine be false, which depends upon them; but is contented to +alledge therein some Inconveniences, and some Repugnances to the +Doctrine and Opinion of _Aristotle_. In answer to which Objections, I +say, first[21], That the being of _Archimedes_ Doctrine, simply different +from the Doctrine of _Aristotle_, ought not to move any to suspect it, +there being no cause, why the Authority of this should be preferred to +the Authority of the other: but, because, where the decrees of Nature +are indifferently exposed to the intellectuall eyes of each, the +Authority of the one and the other, loseth all a{u}thenticalness of +Perswasion, the absolute power residing in Reason; therefore I pass to +that which he alledgeth in the second place[22], as an absurd consequent +of the Doctrine of _Archimedes_, namely, That water should be more +grave than Earth. But I really find not, that ever _Archimedes_ said +such a thing, or that it can be rationally deduced from his +Conclusions: and if that were manifest unto me, I verily believe, I +should renounce his Doctrine, as most erroneous. Perhaps this +Deduction of _Buonamico_, is founded upon that which he citeth of the +Vessel, which swims as long as its voyd of water, but once full it +sinks to the Bottom, and understanding it of a Vessel of Earth, he +infers against _Archimedes_ thus: Thou sayst that the Solids which +swim, are less grave than water: this Vessell swimmeth: therefore, +this Vessell is lesse grave than water. If this be the Illation. I +easily answer, granting that this Vessell is lesse grave than water, +and denying the other consequence, namely, that Earth is less Grave +than Water. The Vessel that swims occupieth in the water, not only a +place equall to the Mass of the Earth, of which it is formed; but +equall to the Earth and to the Air together, contained in its +concavity. And, if such a Mass compounded of Earth and Air, shall be +less grave than such another quantity of water, it shall swim, and +shall accord with the Doctrine of _Archimedes_; but if, again, +removing the Air, the Vessell shall be filled with water, so that the +Solid put in the water, be nothing but Earth, nor occupieth other +place, than that which is only possest by Earth, it shall then go to +the Bottom, by reason that the Earth is heavier than the water: and +this corresponds well with the meaning of _Archimedes_. See the same +effect illustrated, with such another Experiment, In pressing a Viall +Glass to the Bottom of the water, when it is full of Air, it will meet +with great resistance, because it is not the Glass alone, that is +pressed under water, but together with the Glass a great Mass of Air, +and such, that if you should take as much water, as the Mass of the +Glass, and of the Air contained in it, you would have a weight much +greater than that of the Viall, and of its Air: and, therefore, it +will not submerge without great violence: but if we demit only the +Glass into the water, which shall be when you shall fill the Glass +with water, then shall the Glass descend to the Bottom; as superiour +in Gravity to the water. + + [21] The Authors answer to the first Objection. + + [22] The Authors answer to the second Objection. + +Returning, therefore, to our first purpose; I say, that Earth is more +grave than water, and that therefore, a Solid of Earth goeth to the +bottom of it; but one may possibly make a composition of Earth and +Air, which shall be less grave than a like Mass of Water; and this +shall swim: and yet both this and the other experiment shall very well +accord with the Doctrine of _Archimedes_. But because that in my +judgment it hath nothing of difficulty in it, I will not positively +affirme that _Signor Buonamico_, would by such a discourse object unto +_Archimedes_ the absurdity of inferring by his doctrine, that Earth +was less grave than Water, though I know not how to conceive what +other accident he could have induced thence. + +Perhaps such a Probleme (in my judgement false) was read by _Signor +Buonamico_ in some other Author, by whom peradventure it was +attributed as a singular propertie, of some particular Water, and so +comes now to be used with a double errour in confutation of +_Archimedes_, since he saith no such thing, nor by him that did say it +was it meant of the common Element of Water. + + [Sidenote: The Authors answer to the third Objection.] + +The third difficulty in the doctrine of _Archimedes_ was, that he +could not render a reason whence it arose, that a piece of Wood, and a +Vessell of Wood, which otherwise floats, goeth to the bottom, if +filled with Water. _Signor Buonamico_ hath supposed that a Vessell of +Wood, and of Wood that by nature swims, as before is said, goes to the +bottom, if it be filled with water; of which he in the following +Chapter, which is the 30 of the fifth Book copiously discourseth: but +I (speaking alwayes without diminution of his singular Learning) dare +in defence of _Archimedes_ deny this experiment, being certain that a +piece of Wood which by its nature sinks not in Water, shall not sinke +though it be turned and converted into the forme of any Vessell +whatsoever, and then filled with Water: and he that would readily see +the Experiment in some other tractable Matter, and that is easily +reduced into several Figures, may take pure Wax, and making it first +into a Ball or other solid Figure, let him adde to it so much Lead as +shall just carry it to the bottome, so that being a graine less it +could not be able to sinke it, and making it afterwards into the forme +of a Dish, and filling it with Water, he shall finde that without the +said Lead it shall not sinke, and that with the Lead it shall descend +with much slowness: & in short he shall satisfie himself, that the +Water included makes no alteration. I say not all this while, but that +its possible of Wood to make Barkes, which being filled with water, +sinke; but that proceeds not through its Gravity, encreased by the +Water, but rather from the Nailes and other Iron Workes, so that it no +longer hath a Body less grave than Water, but one mixt of Iron and +Wood, more grave than a like Masse of Water. Therefore let _Signor +Buonamico_ desist from desiring a reason of an effect, that is not in +nature: yea if the sinking of the Woodden Vessell when its full of +Water, may call in question the Doctrine of _Archimedes_, which he +would not have you to follow, is on the contrary consonant and +agreeable to the Doctrine of the Peripateticks, since it aptly +assignes a reason why such a Vessell must, when its full of Water, +descend to the bottom; converting the Argument the other way, we may +with safety say that the Doctrine of _Archimedes_ is true, since it +aptly agreeth with true experiments, and question the other, whose +Deductions are fastened upon erroneouss Conclusions. As for the other +point hinted in this same Instance, where it seemes that _Benonamico_ +understands the same not only of a piece of wood, shaped in the forme +of a Vessell, but also of massie Wood, which filled, _scilicet_, as I +believe, he would say, soaked and steeped in Water, goes finally to +the bottom that happens in some porose Woods, which, while their +Porosity is replenished with Air, or other Matter less grave than +Water, are Masses specificially less grave than the said Water, like +as is that Viall of Glass whilest it is full of Air: but when, such +light Matter departing, there succeedeth Water into the same +Porosities and Cavities, there results a compound of Water and Glass +more grave than a like Mass of Water: but the excess of its Gravity +consists in the Matter of the Glass, and not in the Water, which +cannot be graver than it self: so that which remaines of the Wood, the +Air of its Cavities departing, if it shall be more grave _in specie_ +than Water, fil but its Porosities with Water, and you shall have a +Compost of Water and of Wood more grave than Water, but not by vertue +of the Water received into and imbibed by the Porosities, but of that +Matter of the Wood which remains when the Air is departed: and being +such it shall, according to the Doctrine of _Archimedes_, goe to the +bottom, like as before, according to the same Doctrine it did swim. + + [Sidenote: The Authors answer to the fourth Objection.] + +As to that finally which presents itself in the fourth place, +namely, that the _Ancients_ have been heretofore confuted by +_Aristotle_, who denying Positive and Absolute Levity, and truely +esteeming all Bodies to be grave, said, that that which moved upward +was driven by the circumambient Air, and therefore that also the +Doctrine of _Archimedes_, as an adherent to such an Opinion was +convicted and confuted: I answer first, that _Signor Buonamico_ in my +judgement hath imposed upon _Archimedes_, and deduced from his words +more than ever he intended by them, or may from his Propositions be +collected, in regard that _Archimedes_ neither denies, nor admitteth +Positive Levity, nor doth he so much as mention it: so that much less +ought _Buonamico_ to inferre, that he hath denyed that it might be the +Cause and Principle of the Ascension of Fire, and other Light Bodies[23]: +having but only demonstrated, that Solid Bodies more grave than Water +descend in it, according to the excess of their Gravity above the +Gravity of that, he demonstrates likewise, how the less grave ascend +in the same Water[24], accordng to its excess of Gravity, above the +Gravity of them. So that the most that can be gathered from the +Demonstration of _Archimedes_ is, that like as the excess of the +Gravity of the Moveable above the Gravity of the Water, is the Cause +that it descends therein, so the excess of the Gravity of the water +above that of the Moveable, is a sufficient Cause why it descends not, +but rather betakes it self to swim: not enquiring whether of moving +upwards there is, or is not any other Cause contrary to Gravity: nor +doth _Archimedes_ discourse less properly than if one should say: If +the South Winde shall assault the Barke with greater _Impetus_ than is +the violence with which the Streame of the River carries it towards +the South, the motion of it shall be towards the North: but if the +_Impetus_ of the Water shall overcome that of the Winde, its motion +shall be towards the South. The discourse is excellent and would be +unworthily contradicted by such as should oppose it, saying: Thou +mis-alledgest as Cause of the motion of the Bark towards the South, +the _Impetus_ of the Stream of the Water above that of the South +Winde; mis-alledgest I say, for it is the Force of the North Winde +opposite to the South, that is able to drive the Bark towards the +South. Such an Objection would be superfluous, because he which +alledgeth for Cause of the Motion the Stream of the Water, denies not +but that the Winde opposite to the South may do the same, but only +affirmeth that the force of the Water prevailing over the South Wind, +the Bark shall move towards the South: and saith no more than is true. +And just thus when _Archimedes_ saith, that the Gravity of the Water +prevailing over that by which the moveable descends to the Bottom, +such moveable shall be raised from the Bottom to the Surface alledgeth +a very true Cause of such an Accident, nor doth he affirm or deny that +there is, or is not, a vertue contrary to Gravity, called by some +Levity, that hath also a power of moving some Matters upwards. Let +therefore the Weapons of _Signor Buonamico_ be directed against +_Plato_[25], and other _Ancients_, who totally denying _Levity_, and +taking all Bodies to be grave, say that the Motion upwards is made, +not from an intrinsecal Principle of the Moveable, but only by the +Impulse of the _Medium_; and let _Archimedes_ and his Doctrine escape +him, since he hath given him no Cause of quarelling with him. But if +this Apologie, produced in defence of _Archimedes_, should seem to +some insufficient to free him from the Objections and Arguments, +produced by _Aristotle_ against _Plato_, and the other _Ancients_, as if +they did also fight against _Archimedes_, alledging the Impulse of the +Water as the Cause of the swimming of some Bodies less grave than it[26], +I would not question, but that I should be able to maintaine the +Doctrine of _Plato_ and those others to be most true, who absolutely +deny Levity, and affirm no other Intrinsecal Principle of Motion to be +in Elementary Bodies save only that towards the Centre of the Earth[27], +nor no other Cause of moving upwards, speaking of that which hath the +resemblance of natural Motion, but only the repulse of the _Medium_, +fluid, and exceeding the Gravity of the Moveable[28]: and as to the +Reasons of _Aristotle_ on the contrary, I believe that I could be able +fully to answer them, and I would assay to do it, if it were +absolutely necessary to the present Matter, or were it not too long a +Digression for this short Treatise. I will only say, that if there +were in some of our Ellementary Bodies an Intrinsecall Principle and +Naturall Inclination to shun the Centre of the Earth, and to move +towards the Concave of the Moon, such Bodies, without doubt, would +more swiftly ascend through those _Mediums_ that least oppose the +Velocity of the Moveable, and these are the more tenuous and subtle; +as is, for example, the Air in comparison of the Water, we daily +proving that we can with farre more expeditious Velocity move a Hand +or a Board to and again in one than in the other[29]: nevertheless, we +never could finde any Body, that did not ascend much more swiftly in +the water than in the Air. Yea of Bodies which we see continually to +ascend in the Water, there is none that having arrived to the confines +of the Air, do not wholly lose their Motion[30]; even the Air it self, +which rising with great Celerity through the Water, being once come to +its Region it loseth all + + [23] Of Natation, Lib. 1. Prop. 7. + + [24] Of Natation, Lib. 1. Prop. 4. + + [25] _Plato_ denyeth Positive Levity. + + [26] The Authors defence of the doctrine of _Plato_ and the + _Ancients_, who absolutely deny Levity: + + [27] According to _Plato_ there is no Principle of the Motion, of + descent in Naturall Bodies, save that to the Centre. + + [28] No cause of the motion of Ascent, save the Impulse of the + _Medium_, exceeding the Moveable in Gravitie. + + [29] Bodies ascend much swifter in the Water, than in the Air. + + [30] All Bodies ascending through Water, lose their Motion, + comming to the confines of the Air. + + [Sidenote: The lighter Bodies ascend more swiftly through Water.] + +And, howbeit, Experience shewes, that the Bodies, successively less +grave, do most expeditiously ascend in water, it cannot be doubted, +but that the Ignean Exhalations do ascend more swiftly through the +water, than doth the Air: which Air is seen by Experience to ascend +more swiftly through the Water, than the Fiery Exhalations through the +Air[31]: Therefore, we must of necessity conclude, that the said +Exhalations do much more expeditiously ascend through the Water, than +through the Air; and that, consequently, they are moved by the Impulse +of the Ambient _Medium_, and not by an intrinsick Principle that is in +them, of avoiding the Centre of the Earth; to which other grave Bodies +tend. + + [31] Fiery Exhalations ascend thorow the Water more swiftly than + doth the Air; & the Air ascends more swiftly thorow the Water, + than Fire thorow the Air. + + [Sidenote: _T_he Authors confutation of the Peripateticks Causes + of Natation & Submersion.] + +To that which for a finall conclusion, _Signor Buonamico_ produceth +of going about to reduce the descending or not descending, to the +easie and uneasie Division of the _Medium_, and to the predominancy of +the Elements: I answer, as to the first part, that that cannot in any +manner be admitted as a Cause, being that in none of the Fluid +_Mediums_, as the Air, the Water, and other Liquids, there is any +Resistance against Division[32], but all by every the least Force, are +divided and penetrated, as I will anon demonstrate: so, that of such +Resistance of Division there can be no Act, since it self is not in +being. As to the other part, I say, that the predominancy of the +Elements in Moveables[33], is to be considered, as far as to the excesse +or defect of Gravity, in relation to the _Medium_: for in that Action, +the Elements operate not, but only, so far as they are grave or light: +therefore, to say that the Wood of the Firre sinks not, because Air +predominateth in it, is no more than to say, because it is less grave +than the Water. Yea, even the immediate Cause, is its being less grave +than the Water[34]: and it being under the predominancy of the Air, is the +Cause of its less Gravity: Therefore, he that alledgeth the +predominancy of the Element for a Cause, brings the Cause of the +Cause, and not the neerest and immediate Cause. Now, who knows not +that the true Cause is the immediate, and not the mediate[35]? Moreover, +he that alledgeth Gravity, brings a Cause most perspicuous to Sence[36]: +The cause we may very easily assertain our selves; whether Ebony, for +example, and Firre, be more or less grave than water: but whether +Earth or Air predominates in them, who shall make that manifest? +Certainly, no Experiment can better do it than to observe whether they +swim or sink. So, that he who knows, not whether such a Solid swims, +unless when he knows that Air predominates in it, knows not whether it +swim, unless he sees it swim, for then he knows that it swims, when he +knows that it is Air that predominates, but knows not that Air hath +the predominance, unless he sees it swim: therefore, he knows not if +it swims, till such time as he hath seen it swim. + + [32] Water & other fluids void of Resistance against Division. + + [33] _T_he predominancy of Elements in Moveables to be considered + only in relation to their excess or defect of Gravity in reference + to the _Medium_. + + [34] _T_he immediate Cause of Natation is that the Moveable is + less grave than the Water. + + [35] _T_he Peripateticks alledge for the reason of Natation the + Cause of the Cause. + + [36] Gravity a Cause most perspicuous to sence. + +Let us not then despise those Hints, though very dark, which Reason, +after some contemplation, offereth to our Intelligence, and lets be +content to be taught by _Archimedes_, that then any Body shall +submerge in water[37], when it shall be specifically more grave than it, +and that if it shall be less grave[38], it shall of necessity swim, and +that it will rest indifferently in any place under water, if its +Gravity be perfectly like to that of the water. + + [37] Lib 1. of Natation Prop. 7 + + [38] Id. Lib. 1. Prop. 4. + +These things explained and proved[39], I come to consider that which +offers it self, touching what the Diversity of figure given unto the +said Moveable hath to do with these Motions and Rests; and proceed to +affirme, that, + + [39] Id. Lib 1. Prop. 3. + + + + +THEOREME V. + + [Sidenote: Diversity of Figure no Cause of its absolute Natation + or Submersion.] + + _The diversity of Figures given to this or that Solid, cannot any + way be a Cause of its absolute Sinking or Swimming._ + + +So that if a Solid being formed, for example, into a Sphericall +Figure, doth sink or swim in the water, I say, that being formed into +any other Figure, the same figure in the same water, shall sink or +swim: nor can such its Motion by the Expansion or by other mutation of +Figure, be impeded or taken away. + + [Sidenote: The Expansion of Figure, retards the Velocity of the + ascent or descent of the Moveable in the water; but doth not + deprive it of all Motion.] + +The Expansion of the Figure may indeed retard its Velocity, aswell of +ascent as descent, and more and more according as the said Figure is +reduced to a greater breadth and thinness: but that it may be reduced +to such a form as that that same matter be wholly hindred from moving +in the same water, that I hold to be impossible. In this I have met +with great contradictors, who producing some Experiments, and in +perticular a thin Board of Ebony, and a Ball of the same Wood, and +shewing how the Ball in Water descended to the bottom, and the Board +being put lightly upon the Water submerged not, but rested; have held, +and with the Authority of _Aristotle_, confirmed themselves in their +Opinions, that the Cause of that Rest was the breadth of the Figure, +u{n}able by its small weight to pierce and penetrate the Resistance of +the Waters Crassitude, which Resistance is readily overcome by the +other Sphericall Figure. + +This is the Principal point in the present Question, in which I +perswade my self to be on the right side. + +Therefore, beginning to investigate with the examination of exquisite +Experiments that really the Figure doth not a jot alter the descent or +Ascent of the same Solids, and having already demonstrated that the +greater or less Gravity of the Solid in relation to the Gravity of the +_Medium_ is the cause of Descent or Ascent: when ever we would make +proof of that, which about this Effect the diversity of Figure +worketh, its necessary to make the Experiment with Matter wherein +variety of Gravities hath no place. For making use of Matters which +may be different in their Specifical Gravities, and meeting with +varieties of effects of Ascending and Descending, we shall alwayes be +left unsatisfied whether that diversity derive it self really from the +sole Figure, or else from the divers Gravity also. We may remedy this +by takeing one only Matter, that is tractable and easily reduceable +into every sort of Figure. Moreover, it will be an excellent expedient +to take a kinde of Matter, exactly alike in Gravity unto the Water: +for that Matter, as far as pertaines to the Gravity, is indifferent +either to Ascend or Descend; so that we may presently observe any the +least difference that derives it self from the diversity of Figure. + + [Sidenote: An Experiment in Wax, that proveth Figure to have no + Operation in Natation & Submersion.] + +Now to do this, Wax is most apt, which, besides its incapacity of +receiveing any sensible alteration from its imbibing of Water, is +ductile or pliant, and the same piece is easily reduceable into all +Figures: and being _in Specie_ a very inconsiderable matter inferiour +in Gravity to the Water, by mixing therewith a little of the fileings +of Lead it is reduced to a Gravity exactly equall to that of the +Water. + +This Matter prepared, and, for example, a Ball being made thereof as +bigge as an Orange or biger, and that made so grave as to sink to the +bottom, but so lightly, that takeing thence one only Grain of Lead, it +returns to the top, and being added, it submergeth to the bottom, let +the same Wax afterwards be made into a very broad and thin Flake or +Cake; and then, returning to make the same Experiment, you shall see +that it being put to the bottom, it shall, with the Grain of Lead rest +below, and that Grain deducted, it shall ascend to the very Surface, +and added again it shall dive to the bottom. And this same effect +shall happen alwaies in all sort of Figures, as wel regular as +irregular: nor shall you ever finde any that will swim without the +removall of the Grain of Lead, or sinke to the bottom unless it be +added: and, in short, about the going or not going to the Bottom, you +shall discover no diversity, although, indeed, you shall about the +quick and slow descent: for the more expatiated and distended Figures +move more slowly aswel in the diveing to the bottom as in the rising +to the top; and the other more contracted and compact Figures, more +speedily. Now I know not what may be expected from the diversity of +Figures, if the most contrary to one another operate not so much as +doth a very small Grain of Lead, added or removed. + +Me thinkes I hear some of the Adversaries to raise a doubt upon my +produced Experiment[40]. And first that they offer to my consideration, +that the Figure, as a Figure simply, and disjunct from the Matter +workes not any effect, but requires to be conjoyned with the Matter; +and, furthermore, not with every Matter, but with those only, +wherewith it may be able to execute the desired operation. Like as we +see it verified by Experience, that the Acute and sharp Angle is more +apt to cut, than the Obtuse; yet alwaies provided, that both the one +and the other, be joyned with a Matter apt to cut, as for example, +with Steel. Therefore, a Knife with a fine and sharp edge, cuts Bread +or Wood with much ease, which it will not do, if the edge be blunt and +thick: but he that will instead of Steel, take Wax, and mould it into +a Knife, undoubtedly shall never know the effects of sharp and blunt +edges: because neither of them will cut, the Wax being unable by +reason of its flexibility, to overcome the hardness of the Wood and +Bread. And, therefore, applying the like discourse to our purpose, +they say, that the difference of Figure will shew different effects, +touching Natation and Submersion, but not conjoyned with any kind of +Matter, but only with those Matters which, by their Gravity, are apt +to resist the Velocity of the water, whence he that would elect for +the Matter, Cork or other light wood, unable, through its Levity, to +superate the Crassitude of the water, and of that Matter should forme +Solids of divers Figures, would in vain seek to find out what +operation Figure hath in Natation or Submersion; because all would +swim, and that not through any property of this or that Figure, but +through the debility of the Matter, wanting so much Gravity, as is +requisite to superate and overcome the Density and Crassitude of the +water. + + [40] An objection against the Experiment in Water. + +Its needfull, therefore, if wee would see the effect wrought by the +Diversity of Figure, first to make choice of a Matter of its nature +apt to penetrate the Crassitude of the water. And, for this effect[41], +they have made choice of such a Matter, as fit, that being readily +reduced into Sphericall Figure, goes to the Bottom; and it is Ebony, +of which they afterwards making a small Board or Splinter, as thin as +a Lath, have illustrated how that this, put upon the Surface of the +water, rests there without descending to the Bottom: and making, on +the otherside, of the same wood a Ball, no less than a hazell Nut, +they shew, that this swims not, but descendes. From which Experiment, +they think they may frankly conclude, that the Breadth of the Figure +in the flat Lath or Board, is the cause of its not descending to the +Bottom, for as much as a Ball of the same Matter, not different from +the Board in any thing but in Figure, submergeth in the same water to +the Bottom. The discourse and the Experiment hath really so much of +probability and likelyhood of truth in it, that it would be no wonder, +if many perswaded by a certain cursory observation, should yield +credit to it; nevertheless, I think I am able to discover, how that it +is not free from falacy. + + [41] An Experiment in Ebany, brought to disprove the Experiment + in Wax. + +Beginning, therefore, to examine one by one, all the particulars that +have been produced, I say, that Figures, as simple Figures, not only +operate not in naturall things, but neither are they ever seperated +from the Corporeall substance[42]: nor have I ever alledged them stript of +sensible Matter, like as also I freely admit, that in our endeavouring +to examine the Diversity of Accidents, dependant upon the variety of +Figures, it is necessary to apply them to Matters, which obstruct not +the various operations of those various Figures: and I admit and +grant, that I should do very ill; if I would experiment the influence +of Acutenesse of edge with a Knife of Wax, applying it to cut an Oak, +because there is no Acuteness in Wax able to cut that very hard wood. +But yet such an Experiment of this Knife, would not be besides the +purpose, to cut curded Milk, or other very yielding Matter: yea, in +such like Matters, the Wax is more commodious than Steel; for finding +the diversity depending upon Angles, more or less Acute, for that Milk +is indifferently cut with a Raisor, and with a Knife, that hath a +blunt edge. It needs, therefore, that regard be had, not only to the +hardness, solidity or Gravity of Bodies, which under divers figures, +are to divide and penetrate some Matters, but it forceth also, that +regard be had, on the other side, to the Resistance of the Matters, to +be divided and penetrated. But since I have in making the Experiment +concerning our Contest; chosen a Matter which penetrates the +Resistance of the water; and in all figures descendes to the Bottome, +the Adversaries can charge me with no defect; yea, I have propounded +so much a more excellent Method than they, in as much as I have +removed all other Causes, of descending or not descending to the +Bottom, and retained the only sole and pure variety of Figures, +demonstrating that the same Figures all descende with the only +alteration of a Grain in weight: which Grain being removed, they +return to float and swim; it is not true, therefore, (resuming the +Example by them introduced) that I have gon{e} about to experiment the +efficacy of Acuteness, in cutting with Matters unable to cut, but with +Matters proportioned to our occasion, since they are subjected to no +other variety, then that alone which depends on the Figure more or +less acute. + + [42] Figure is unseperable from Corporeall Substance. + + [Sidenote: The answer to the Objection against the Experiment of + the Wax.] + +But let us proceed a little farther, and observe, how that indeed the +Consideration, which, they say, ought to be had about the Election of +the Matter, to the end, that it may be proportionate for the making of +our experiment, is needlessly introduced, declaring by the example of +Cutting, that like as Acuteness is inefficient to cut, unless when it +is in a Matter hard and apt to superate the Resistance of the wood or +other Matter, which we intend to cut; so the aptitude of descending or +not descending in water, ought and can only be known in those Matters, +that are able to overcome the Renitence, and superate the Crassitude +of the water. Unto which, I say, that to make distinction and +election, more of this than of that Matter, on which to impress the +Figures for cutting or penetrating this or that Body, as the solidity +or obdurateness of the said Bodies shall be greater or less, is very +necessary: but withall I subjoyn, that such distinction, election and +caution would be superfluous and unprofitable, if the Body to be cut +or penetrated, should have no Resistance, or should not at all +withstand the Cutting or Penitration: and if the Knife were to be used +in cutting a Mist or Smoak, one of Paper would be equally serviceable +with one of _Damascus_ Steel: and so by reason the water hath not any +Resistance against the Penitration of any Solid Body, all choice of +Matter is superfluous and needless, and the Election which I said +above to have been well made of a Matter reciprocall in Gravity to +water, was not because it was necessary, for the overcoming of the +crassitude of the water, but its Gravity, with which only it resists +the sinking of Solid Bodies: and for what concerneth the Resistance of +the crassitude, if we narrowly consider it, we shall find that all +Solid Bodies, as well those that sink, as those that swim, are +indifferently accomodated and apt to bring us to the knowledge of the +truth in question. Nor will I be frighted out of the belief of these +Conclusions, by the Experiments which may be produced against me, of +many severall Woods, Corks, Galls, and, moreover, of subtle slates and +plates of all sorts of Stone and Mettall, apt by means of their +Naturall Gravity, to move towards the Centre of the Earth, the which, +nevertheless, being impotent, either through the Figure (as the +Adversaries thinke) or through Levity, to break and penetrate the +Continuity of the parts of the water, and to distract its union, do +continue to swimm without submerging in the least: nor on the other +side, shall the Authority of _Aristotle_ move me, who in more than one +place, affirmeth the contrary to this, which Experience shews me. + + [Sidenote: No Solid of such Levity, nor of such Figure, but that + it doth penetrate the Crassitude of the Water.] + + [Sidenote: Bodies of all Figures, laid upon the water, do + penetrate its Crassitude, and in what proportion.] + +I return, therefore, to assert, that there is not any Solid of such +Levity, nor of such Figure, that being put upon the water, doth not +divide and penetrate its Crassitude: yea if any with a more +perspicatious eye, shall return to observe more exactly the thin +Boards of Wood, he shall see them to be with part of their thickness +under water, and not only with their inferiour Superficies, to kisse +the Superiour of the water, as they of necessity must have believed, +who have said, that such Boards submerge not, as not being able to +divide the Tenacity of the parts of the water: and, moreover, he shall +see, that subtle shivers of Ebony, Stone or Metall, when they float, +have not only broak the Continuity of the water, but are with all +their thickness, under the Surface of it; and more and more, according +as the Matters are more grave: so that a thin Plate of Lead, shall be +lower than the Surface of the circumfused water, by at least twelve +times the thickness of the Plate, and Gold shall dive below the Levell +of the water, almost twenty times the thickness of the Plate, as I +shall anon declare. + +But let us proceed to evince, that the water yields and suffers it +self to be penetrated by every the lightest Body; and therewithall +demonstrate, how, even by Matters that submerge not, we may come to +know that Figure operates nothing about the going or not going to the +Bottom, seeing that the water suffers it self to be penetrated equally +by every Figure. + + [Sidenote: The Experiment of a Cone, demitted with its Base, and + after with its Point downwards.] + +Make a Cone, or a Piramis of Cypress, of Firre, or of other Wood of +like Gravity, or of pure Wax, and let its height be somewhat great, +namely a handfull, or more, and put it into the water with the Base +downwards: first, you shall see that it will penetrate the water, nor +shall it be at all impeded by the largeness of the Base, nor yet shall +it sink all under water, but the part towards the point shall lye +above it: by which shall be manifest, first, that that Solid forbeares +not to sink out of an inability to divide the Continuity of the water, +having already divided it with its broad part, that in the opinion of +the Adversaries is the less apt to make the division. The Piramid +being thus fixed, note what part of it shall be submerged, and revert +it afterwards with the point downwards, and you shall see that it +shall not dive into the water more than before, but if you observe how +far it shall sink, every person expert in Geometry, may measure, that +those parts that remain out of the water, both in the one and in the +other Experiment are equall to an hair: whence he may manifestly +conclude, that the acute Figure which seemed most apt to part and +penetrate the water, doth not part or penetrate it more than the large +and spacious. + +And he that would have a more easie Experiment, let him take two +Cylinders of the same Matter, one long and small, and the other short, +but very broad, and let him put them in the water, not distended, but +erect and endways: he shall see, if he diligently measure the parts of +the one and of the other, that in each of them the part submerged, +retains exactly the same proportion to that out of the water, and that +no greater part is submerged of that long and small one, than of the +other more spacious and broad: howbeit, this rests upon a very large, +and that upon a very little Superficies of water: therefore the +diversity of Figure, occasioneth neither facility, nor difficulty, in +parting and penetrating the Continuity of the water, and, +consequently, cannot be the Cause of the Natation or Submersion. He +may likewise discover the non operating of variety of Figures, in +arising from the Bottom of the water, towards the Surface, by taking +Wax, and tempering it with a competent quantity of the filings of +Lead, so that it may become a considerable matter graver than the +water: then let him make it into a Ball, and thrust it unto the Bottom +of the water; and fasten to it as much Cork, or other light matter, as +just serveth to raise it, and draw it towards the Surface: for +afterwards changing the same Wax into a thin Cake, or into any other +Figure, that same Cork shall raise it in the same manner to a hair. + +This silenceth not my Antagonists, but they say, that all the +discourse hitherto made by me little importeth to them, and that it +serves their turn, that they have demonstrated in one only particular, +and in what matter, and under what Figure pleaseth them, namely, in a +Board and in a Ball of Ebony, that this put in the water, descends to +the Bottom, and that stays atop to swim: and the Matter being the +same, and the two Bodies differing in nothing but in Figure, they +affirm, that they have with all perspicuity demonstrated and sensibly +manifested what they undertook; and lastly, that they have obtained +their intent. Nevertheless, I believe, and thinke, I can demonstrate, +that that same Experiment proveth nothing against my Conclusion. + + [Sidenote: In Experiments of Natation, the Solid is to be put + into, not upon the water.] + +And first, it is false, that the Ball descends, and the Board not: for +the Board shall also descend, if you do to both the Figures, as the +words of our Question requireth; that is, if you put them both into +the water. + + [Sidenote: The Question of Natation stated.] + + _The words were these. That the Antagonists having an opinion, that + the Figure would alter the Solid Bodies, in relation to the + descending or not descending, ascending or not ascending in the + same_ Medium, _as_ v. gr. _in the same water, in such sort, that, for + Example, a Solid that being of a Sphericall Figure, shall descend + to the Bottom, being reduced into some other Figure, shall not + descend: I holding the contrary, do affirm, that a Corporeall Solid + Body, which reduced into a Sphericall Figure, or any other, shall + go to the Bottom, shall do the like under whatsoever other Figure, + {&}c._ + + [Sidenote: Place defined according to Aristotle.] + +But to be in the water, implies to be placed in the water, and by +_Aristotles_ own Definition of place, to be placed, importeth to be +invironed by the Superficies of the Ambient Body, therefore, then +shall the two Figures be in the water, when the Superficies of the +water, shall imbrace and inviron them: but when the Adversaries shew +the Board of Ebony not descending to the Bottom, they put it not into +the water, but upon the water, where being by a certain impediment (as +by and by we will shew) retained, it is invironed, part by water, and +part by air, which thing is contrary to our agreement, that was, that +the Bodies should be in the water, and not part in water, and part in +air. + + _The which is again made manifest, by the questions being put as + well about the things which go to the Bottom, as those which arise + from the Bottom to swimme, and who sees not that things placed in + the Bottom, must have water about them._ + + [Sidenote: The confutation of the Experiment in the Ebany.] + +It is now to be noted, that the Board of Ebany and the Ball, put into +the water, both sink, but the Ball more swiftly, and the Board more +slowly; and slower and slower, according as it shall be more broad and +thin, and of this Tardity the breadth of the Figure is the true Cause: +But these broad Boards that slowly descend, are the same, that being +put lightly upon the water, do swimm: Therefore, if that were true +which the Adversaries affirm, the same numerical Figure, would in the +same numericall water, cause one while Rest, and another while Tardity +of Motion, which is impossible: for every perticular Figure which +descends to the Bottom[43], hath of necessity its own determinate Tardity +and slowness, proper and naturall unto it, according to which it +moveth, so that every other Tardity, greater or lesser is improper to +its nature: if, therefore, a Board, as suppose of a foot square, +descendeth naturally with six degrees of Tardity, it is impossible, +that it should descend with ten or twenty, unless some new impediment +do arrest it. Much less can it, by reason of the same Figure rest, and +wholly cease to move; but it is necessary, that when ever it resteth, +there do some greater impediment intervene than the breadth of the +Figure. Therefore, it must be somewhat else, and not the Figure, that +stayeth the Board of Ebany above water, of which Figure the only +Effect is the retardment of the Motion, according to which it +descendeth more slowly than the Ball. Let it be confessed, therefore, +rationally discoursing, that the true and sole Cause of the Ebanys +going to the Bottom, is the excess of its Gravity above the Gravity of +the water: and the Cause of the greater or less Tardity, the breadth +of this Figure, or the contractedness of that: but of its Rest, it can +by no means be allowed, that the quallity of the Figure, is the Cause +thereof: aswell, because, making the Tardity greater, according as the +Figure more dilateth, there cannot be so immense a Dilatation, to +which there may not be found a correspondent immence Tardity without +redusing it to Nullity of Motion; as, because the Figures produced by +the Antagonists for effecters of Rest, are the self same that do also +go to the Bottom. + + [43] Every perticular Figure hath its own peculiar Tardity. + +I will not omit another reason, founded also upon Experience, and if +I deceive not my self, manifestly concluding, how that the +Introduction of the breadth or amplitude of Figure, and the Resistance +of the water against penetration, have nothing to do in the Effect of +descending, or ascending, or resting in the water. [D]Take a piece of +wood or other Matter, of which a Ball ascends from the Bottom of the +water to the Surface, more slowly than a Ball of Ebony of the same +bignesse, so that it is manifest, that the Ball of Ebony more readily +divideth the water in descending, than the other in ascending; as for +Example, let the Wood be Walnut-tree. Then take a Board of +Walnut-tree, like and equall to that of Ebony of the Antagonists, +which swims; and if it be true, that this floats above water, by +reason of the Figure, unable through its breadth, to pierce the +Crassitude of the same, the other of Wallnut-tree, without all +question, being thrust unto the Bottom, will stay there, as less apt, +through the same impediment of Figure, to divide the said Resistance +of the water. But if we shall find, and by experience see, that not +only the thin Board, but every other Figure of the same Wallnut-tree +will return to float, as undoubtedly we shall, then I must desier my +opposers to forbear to attribute the floating of the Ebony, unto the +Figure of the Board, in regard that the Resistance of the water is the +same, as well to the ascent, as to the descent, and the force of the +Wallnut-trees ascension, is lesse than the Ebonys force in going to +the Bottom. + + [D] The Figure & Resistance of the Medium against Division, have + nothing to do with the Effect of Natation or Submersion, by an + Experiment in Wallnut tree. + + [Sidenote: An Experiment in Gold, to prove the non-operating of + Figure in Natation and Submersion.] + +Nay, I will say more, that if we shall consider Gold in comparison of +water, we shall find, that it exceeds it in Gravity almost twenty +times, so that the Force and Impetus, wherewith a Ball of Gold goes to +the Bottom, is very great. On the contrary, there want not matters, as +Virgins Wax, and some Woods, which are not above a fiftieth part less +grave than water, whereupon their Ascension therein is very slow, and +a thousand times weaker than the _Impetus_ of the Golds descent: yet +notwithstanding, a plate of Gold swims without descending to the +Bottom, and, on the contrary, we cannot make a Cake of Wax, or thin +Board of Wood, which put in the Bottom of the Water, shall rest there +without ascending. Now if the Figure can obstruct the Penetration, and +impede the descent of Gold, that hath so great an _Impetus_, how can +it choose but suffice to resist the same Penetration of the other +matter in ascending, when as it hath scarce a thousandth part of the +_Impetus_ that the Gold hath in descending? Its therefore, necessary, +that that which suspends the thin Plate of Gold, or Board of Ebony, +upon the water, be some thing that is wanting to the other Cakes and +Boards of Matters less grave than the water; since that being put to +the Bottom, and left at liberty, they rise up to the Surface, without +any obstruction: But they want not for flatness and breadth of Figure: +Therefore, the spaciousnesse of the Figure, is not that which makes +the Gold and Ebony to swim. + +And, because, that the excess of their Gravity above the Gravity of +the water, is questionless the Cause of the sinking of the flat piece +of Ebony, and the thin Plate of Gold, when they go to the Bottom, +therefore, of necessity, when they float, the Cause of their staying +above water, proceeds from Levity, which in that case, by some +Accident, peradventure not hitherto observed, cometh to meet with the +said Board, rendering it no longer as it was before, whilst it did +sink more ponderous than the water, but less. + +Now, let us return to take the thin Plate of Gold, or of Silver, or +the thin Board of Ebony, and let us lay it lightly upon the water, so +that it stay there without sinking, and diligently observe its effect. +And first, see how false the assertion of _Aristotle_, and our +oponents is, to wit, that it stayeth above water, through its +unability to pierce and penetrate the Resistance of the waters +Crassitude: for it will manifestly appear, not only that the said +Plates have penetrated the water, but also that they are a +considerable matter lower than the Surface of the same, the which +continueth eminent, and maketh as it were a Rampert on all sides, +round about the said Plates, the profundity of which they stay +swimming: and, according as the said Plates shall be more grave than +the water, two, four, ten or twenty times, it is necessary, that their +Superficies do stay below the universall Surface of the water, so much +more, than the thickness of those Plates, as we shal more distinctly +shew anon. In the mean space, for the more easie understanding of what +I say, observe with me a little the present Scheme: in which let us +suppose the Surface of the water to be distended, according to the +Lines F L D B, upon which if one shall put a board of matter +specifically more grave than water, but so lightly that it submerge +not, it shall not rest any thing above, but shall enter with its whole +thickness into the water: and, moreover, shall sink also, as we see by +the Board A I, O I, whose breadth is wholly sunk into the water, the +little Ramperts of water L A and D O incompassing it, whose +Superficies is notably higher than the Superficies of the Board. See +now whether it be true, that the said Board goes not to the Bottom, as +being of Figure unapt to penetrate the Crassitude of the water. + +[Illustration] + + [Sidenote: Why solids having penitrated the Water, do not proceed + to a totall Submersion.] + +But, if it hath already penetrated, and overcome the Continuity of +the water, & is of its own nature more grave than the said water, why +doth it not proceed in its sinking, but stop and suspend its self +within that little dimple or cavitie, which with its ponderosity it +hath made in the water? I answer; because that in submerging it self, +so far as till its Superficies come to the Levell with that of the +water, it loseth a part of its Gravity, and loseth the rest of it as +it submergeth & descends beneath the Surface of the water, which +maketh Ramperts and Banks round about it, and it sustaines this loss +by means of its drawing after it, and carrying along with it, the Air +that is above it, and by Contact adherent to it, which Air succeeds to +fill the Cavity that is invironed by the Ramperts of water; so that +that which in this case descends and is placed in the water, is not +only the Board of Ebony or Plate of Iron, but a composition of Ebony +and Air, from which resulteth a Solid no longer superiour in Gravity +to the water, as was the simple Ebony, or the simple Gold. And, if we +exactly consider, what, and how great the Solid is, that in this +Experiment enters into the water, and contrasts with the Gravity of +the same, it will be found to be all that which we find to be beneath +the Surface of the water, the which is an aggregate and Compound of a +Board of Ebony, and of almost the like quantity of Air, or a Mass +compounded of a Plate of Lead, and ten or twelve times as much Air. +But, Gentlemen, you that are my Antagonists in our Question, we +require the Identity of Matter, and the alteration only of the Figure; +therefore, you must remove that Air, which being conjoyned with the +Board, makes it become another Body less grave than the Water, and put +only the Ebony into the Water, and you shall certainly see the Board +descend to the Bottom; and, if that do not happen, you have got the +day. And to seperate the Air from the Ebony[44], there needs no more but +only to bath the Superficies of the said Board with the same Water: +for the Water being thus interposed between the Board and the Air, the +other circumfused Water shall run together without any impediment, and +shall receive into it the sole and bare Ebony, as it was to do. + + [44] How to seperate the Air from Solids in demitting them into + the water. + +But, me thinks I hear some of the Adversaries cunningly opposing this, +and telling me, that they will not yield, by any means, that their +Board be wetted, because the weight added thereto by the Water, by +making it heavier than it was before, draws it to the Bottom, and that +the addition of new weight is contrary to our agreement, which was, +that the Matter be the same. + +To this, I answer, first; that treating of the operation of Figure +in Bodies put into the Water, none can suppose them to be put into the +Water without being wet; nor do I desire more to be done to the Board, +then I will give you leave to do to the Ball. Moreover, it is untrue, +that the Board sinks by vertue of the new Weight added to it by the +Water, in the single and slight bathing of it: for I will put ten or +twenty drops of Water upon the same Board, whilst it is sustained upon +the water; which drops, because not conjoyned with the other Water +circumfused, shall not so encrease the weight of it, as to make it +sink: but if the Board being taken out, and all the water wiped off +that was added thereto, I should bath all its Superficies with one +only very small drop, and put it again upon the water, without doubt +it shall sink, the other Water running to cover it, not being retained +by the superiour Air; which Air by the interposition of the thin vail +of water, that takes away its Contiguity unto the Ebony, shall without +Renitence be seperated, nor doth it in the least oppose the succession +of the other Water: but rather, to speak better, it shall descend +freely; because it shall be all invironed and covered with water, as +soon as its superiour Superficies, before vailed with water, doth +arrive to the Levell of the universall Surface of the said water. To +say, in the next place, that water can encrease the weight of things +that are demitted into it, is most false; for water hath no Gravity in +water[45], since it descends not: yea, if we would well consider what any +immense Mass of water doth put upon a grave Body; that is placed in +it, we shall find experimentally, that it, on the contrary, will +rather in a great part deminish the weight of it[46], and that we may be +able to lift an huge Stone from the Bottom of the water, which the +water being removed, we are not able to stir. Nor let them tell me by +way of reply, that although the superposed water augment not the +Gravity of things that are in it, yet it increaseth the ponderosity of +those that swim, and are part in the water and part in the Air, as is +seen, for Example, in a Brass Ketle[47], which whilst it is empty of +water, and replenished only with Air shall swim, but pouring of Water +therein, it shall become so grave, that it shall sink to the Bottom, +and that by reason of the new weight added thereto. To this I will +return answer, as above, that the Gravity of the Water, contained in +the Vessel is not that which sinks it to the Bottom, but the proper +Gravity of the Brass, superiour to the Specificall Gravity of the +Water: for if the Vessel were less grave than water, the Ocean would +not suffice to submerge it[48]. And, give me leave to repeat it again, as +the fundamentall and principall point in this Case, that the Air +contained in this Vessel before the infusion of the Water, was that +which kept it a-float[49], since that there was made of it, and of the +Brass, a Composition less grave than an equall quantity of Water: and +the place that the Vessel occupyeth in the Water whilst it floats, is +not equall to the Brass alone, but to the Brass and to the Air +together, which filleth that part of the Vessel that is below the +Levell of the water: Moreover, when the Water is infused, the Air is +removed, and there is a composition made of Brass and of water, more +grave _in specie_ than the simple water, but not by vertue of the +water infused, as having greater Specifick Gravity than the other +water, but through the proper Gravity of the Brass, and through the +alienation of the Air. Now, as he that should say that Brass, that by +its nature goes to the Bottom, being formed into the Figure of a +Ketle[50], acquireth from that Figure a vertue of lying in the Water +without sinking, would say that which is false; because that Brass +fashioned into any whatever Figure, goeth always to the Bottom, +provided, that that which is put into the water be simple Brass; and +it is not the Figure of the Vessel that makes the Brass to float, but +it is because that that is not purely Brass which is put into the +water, but an aggregate of Brass and of Air: so is it neither more nor +less false, that a thin Plate of Brass or of Ebony, swims by vertue of +its dilated & broad Figure: for the truth is, that it bares up without +submerging, because that that which is put in the water, is not pure +Brass or simple Ebony, but an aggregate of Brass and Air, or of Ebony +and Air. And, this is not contrary unto my Conclusion, the which, +(having many a time seen Vessels of Mettall, and thin pieces of +diverse grave Matters float, by vertue of the Air conjoyned with them) +did affirm, That Figure was not the Cause of the Natation or +Submersion of such Solids as were placed in the water. Nay more, I +cannot omit, but must tell my Antagonists, that this new conceit of +denying that the Superficies of the Board should be bathed, may beget +in a third person an opinion of a poverty of Arguments of defence on +their part, since that such bathing was never insisted upon by them in +the beginning of our Dispute, and was not questioned in the least, +being that the Originall of the discourse arose upon the swiming of +Flakes of Ice, wherein it would be simplicity to require that their +Superficies might bedry: besides, that whether these pieces of Ice be +wet or dry they alwayes swim, and as the Adversaries say, by reason of +the Figure. + + [45] Water hath no Gravity in Water. + + [46] Water deminisheth the Gravity of Solids immerged therein. + + [47] The Experiment of a brass Ketle swiming when empty, & sinking + when full, alledged to prove that water gravitates in water, + answered. + + [48] An Ocean sufficeth not to sink a Vessel specifically less + grave than water. + + [49] Air, the Cause of the Natation of empty Vessels of Matters + graver _in specie_ than the water. + + [50] Neither Figure, nor the breadth of Figure, is the Cause of + Natation. + +Some peradventure, by way of defence, may say, that wetting the Board +of Ebony, and that in the superiour Superficies, it would, though of +it self unable to pierce and penetrate the water, be born downwards, +if not by the weight of the additionall water, at least by that desire +and propension that the superiour parts of the water have to re-unite +and rejoyn themselves: by the Motion of which parts, the said Board +cometh in a certain manner, to be depressed downwards. + + [Sidenote: The Bathed Solid descends not out of any affectation + of union in the upper parts of the water.] + +This weak Refuge will be removed, if we do but consider, that the +repugnancy of the inferiour parts of the water, is as great against +Dis-union, as the Inclination of its superiour parts is to union: nor +can the uper unite themselves without depressing the board, nor can it +descend without disuniting the parts of the nether Water: so that it +doth follow, by necessary consequence, that for those respects, it +shall not descend. Moreover, the same that may be said of the upper +parts of the water, may with equall reason be said of the nether, +namely, that desiring to unite, they shall force the said Board +upwards. + +Happily, some of these Gentlemen that dissent from me, will wonder, +that I affirm, that the contiguous superiour Air is able to sustain +that Plate of Brass or of Silver, that stayeth above water; as if I +would in a certain sence allow the Air[51], a kind of Magnetick vertue of +sustaining the grave Bodies, with which it is contiguous. To satisfie +all I may, to all doubts, I have been considering how by some other +sensible Experiment I might demonstrate, how truly that little +contiguous and superiour Air sustaines those Solids, which being by +nature apt to descend to the Bottom, being placed lightly on the water +submerge not, unless they be first thorowly bathed; and have found, +that one of these Bodies having descended to the Bottom, by +conveighing to it (without touching it in the least) a little Air, +which conjoyneth with the top of the same, it becometh sufficient, not +only, as before to sustain it, but also to raise it, and to carry it +back to the top, where it stays and abideth in the same manner, till +such time, as the assistance of the conjoyned Air is taken away. And +to this effect, I have taken a Ball of Wax, and made it with a little +Lead, so grave, that it leasurely descends to the Bottom, making with +all its Superficies very smooth and pollite: and this being put gently +into the water, almost wholly submergeth, there remaining vissible +only a little of the very top[52], the which so long as it is conjoyned +with the Air, shall retain the Ball a-top, but the Contiguity of the +Air taken away by wetting it, it shall descend to the Bottom and there +remain. Now to make it by vertue of the Air, that before sustained it +to return again to the top, and stay there, thrust into the water a +Glass reversed with the mouth downwards, the which shall carry with it +the Air it contains, and move this towards the Ball, abasing it till +such time that you see, by the transparency of the Glass, that the +contained Air do arrive to the summity of the _B_all[53]: then gently +withdraw the Glass upwards, and you shall see the _B_all to rise, and +afterwards stay on the top of the water[54], if you carefully part the +Glass and the water without overmuch commoving and disturbing it. +There is, therefore, a certain affinity between the Air and other +Bodies, which holds them unied, so, that they seperate not without a +kind of violence. The same likewise is seen in the water[55]; for if we +shall wholly submerge some Body in it, so that it be thorowly bathed, +in the drawing of it afterwards gently out again, we shall see the +water follow it, and rise notably above its Surface, before it +seperates from it. Solid Bodies, also[56], if they be equall and alike in +Superficies, so, that they make an exact Contact without the +interposition of the least Air, that may part them in the seperation +and yield untill that the ambient _Medium_ succeeds to replenish the +place, do hold very firmly conjoyned, and are not to be seperated +without great force but, because, the Air, Water, and other Liquids, +very expeditiously shape themselves to contact with any Solid +_B_odies, so that their Superficies do exquisitely adopt themselves to +that of the Solids, without any thing remaining between them, +therefore, the effect of this Conjunction and Adherence is more +manifestly and frequently observed in them, than in hard and +inflexible Bodies, whose Superficies do very rarely conjoyn with +exactness of Contact[57]. This is therefore that Magnetick vertue, which +with firm Connection conjoyneth all Bodies, that do touch without the +interposition of flexible fluids; and, who knows, but that that a +Contact, when it is very exact, may be a sufficient Cause of the Union +and Continuity of the parts of a naturall _B_ody? + + [51] _A_ Magnetisme in the _A_ir, by which it bears up those + Solids in the water, that are contiguous with it. + + [52] The Effect of the Airs Contiguity in the Natation of Solids. + + [53] The force of Contact. + + [54] _A_n Affectation of Conjunction betwixt Solids and the Air + contiguous to them. + + [55] The like affectation of Conjunction betwixt Solids & the + water. + + [56] Also the like affectation and Conjunction betwixt Solids + themselves. + + [57] Contact may be the Cause of the Continuity of Naturall + Bodies. + +Now, pursuing my purpose, I say; that it needs not, that we have +recourse to the Tenacity, that the parts of the water have amongst +themselves, by which they resist and oppose Division, Distraction, and +Seperation, because there is no such Coherence and Resistance of +Division for if there were, it would be no less in the internall parts +than in those nearer the superiour or externall Surface, so that the +same Board, finding alwayes the same Resistance and Renitence, would +no less stop in the middle of the water than about the Surface, which +is false. Moreover, what Resistance can we place in the Continuity of +the water, if we see that it is impossible to find any Body of +whatsoever Matter, Figure or Magnitude, which being put into the +water, shall be obstructed and impeded by the Tenacity of the parts of +the water to one another, so, but that it is moved upwards or +downwards, according as the Cause of their Motion transports it? And, +what greater proof of it can we desier, than that which we daily see +in Muddy waters, which being put into Vessels to be drunk, and being, +after some hours setling[58], still, as we say, thick in the end, after +four or six dayes they are wholly setled, and become pure and clear? +Nor can their Resistance of Penetration stay those impalpable and +insensible Atomes of Sand, which by reason of their exceeding small +force, spend six dayes in descending the space of half a yard. + + [58] The settlement of _M_uddy Water, proveth that that Element + hath no aversion to Division. + + _Nor let them say, that the seeing of such small Bodies, consume + six dayes in descending so little a way, is a sufficient Argument + of the Waters Resistance of Division; because that is no resisting + of Division, but a retarding of Motion; and it would be simplicity + to say, that a thing opposeth Division[59], and that in the same + instant, it permits it self to be divided: nor doth the Retardation + of Motion at all favour the Adversaries cause, for that they are to + instance in a thing that wholly prohibiteth Motion, and procureth + Rest; it is necessary, therefore, to find out Bodies that stay in + the water, if one would shew its repugnancy to Division, and not + such as move in it, howbeit but slowly._ + + [59] Water cannot oppose division, and at the same time permit it + self to be divided. + +What then is this Crassitude of the water, with which it resisteth +Division? What, I beseech you, should it be, if we (as we have said +above) with all diligence attempting the reduction of a Matter into so +like a Gravity with the water, that forming it into a dilated Plate it +rests suspended as we have said, between the two waters, it be +impossible to effect it, though we bring them to such an +Equiponderance, that as much Lead as the fourth part of a Grain of +Musterd-seed, added to the same expanded Plate, that in Air [_i. e. +out of the water_] shall weigh four or six pounds, sinketh it to the +Bottom, and being substracted, it ascends to the Surface of the water? +I cannot see, (if what I say be true, as it is most certain) what +minute vertue and force we can possibly find or imagine, to which the +Resistance of the water against Division and Penetration is not +inferiour; whereupon, we must of necessity conclude that it is +nothing: because, if it were of any sensible power, some large Plate +might be found or compounded of a Matter alike in Gravity to the +water, which not only would stay between the two waters; but, +moreover, should not be able to descend or ascend without notable +force. We may likewise collect the same from an other Experiment[60], +shewing that the Water gives way also in the same manner to +transversall Division; for if in a setled and standing water we should +place any great Mass that goeth not to the bottom, drawing it with a +single Womans Hair, we might carry it from place to place without any +opposition, and this whatever Figure it hath, though that it possess a +great space of water, as for instance, a great Beam would do moved +side-ways. Perhaps some might oppose me and say, that if the +Resistance of water against Division, as I affirm, were nothing; Ships +should not need such a force of Oars and Sayles for the moving of them +from place to place in a tranquile Sea, or standing Lake. To him that +should make such an objection, I would reply[61], that the water +contrasteth not against, nor simply resisteth Division, but a sudden +Division, and with so much greater Renitence, by how much greater the +Velocity is: and the Cause of this Resistance depends not on +Crassitude, or any other thing that absolutely opposeth Division, but +because that the parts of the water divided, in giving way to that +Solid that is moved in it, are themselves also necessitated locally to +move, some to the one side, and some to the other, and some downwards: +and this must no less be done by the waves before the Ship, or other +Body swimming through the water, than by the posteriour and +subsequent; because, the Ship proceeding forwards, to make it self a +way to receive its Bulk, it is requisite, that with the Prow it +repulse the adjacent parts of the water, as well on one hand as on the +other, and that it move them as much transversly, as is the half of +the breadth of the Hull: and the like removall must those waves make, +that succeeding the Poump do run from the remoter parts of the Ship +towards those of the middle, successively to replenish the places, +which the Ship in advancing forwards, goeth, leaving vacant. Now, +because, all Motitions are made in Time[62], and the longer in greater +time: and it being moreover true, that those Bodies that in a certain +time are moved by a certain power such a certain space, shall not be +moved the same space, and in a shorter Time, unless by a greater +Power: therefore, the broader Ships move slower than the narrower, +being put on by an equall Force: and the same Vessel requires so much +greater force of Wind, or Oars, the faster it is to move. + + [60] An hair will draw a great Mass thorow the Water; which + proveth, that it hath no Resistance against transversall + Division. + + [61] How ships are moved in the water. + + [62] Bodies moved a certain space in a certain Time, by a + certain power, cannot be moved the same space and in a shorter + time, but by a greater power. + + _But yet for all this, any great Mass swimming in a standing Lake, + may be moved by any petit force; only it is true, that a lesser + force more slowly moves it: but if the waters Resistance of + Division, were in any manner sensible, it would follow, that the + said Mass, should, notwithstanding the percussion of some sensible + force, continue immoveable, which is not so[63]. Yea, I will say + farther, that should we retire our selves into the more internall + contemplation of the Nature of water and other Fluids, perhaps we + should discover the Constitution of their parts to be such, that + they not only do not oppose Division, but that they have not any + thing in them to be divided: so that the Resistance that is + observed in moving through the water[64], is like to that which we meet + with in passing through a great Throng of People, wherein we find + impediment, and not by any difficulty in the Division, for that + none of those persons are divided whereof the Croud is composed, + but only in moving of those persons side-ways which were before + divided and disjoyned: and thus we find Resistance in thrusting a + Stick into an heap of Sand, not because any part of the Sand is to + be cut in pieces, but only to be moved and raised[65]. Two manners of + Penetration, therefore, offer themselves to us, one in Bodies, + whose parts were continuall, and here Division seemeth necessary, + the other in the aggregates of parts not continuall, but contiguous + only[66], and here there is no necessity of dividing but of moving + only. Now, I am not well resolved, whether water and other Fluids + may be esteemed to be of parts continuall or contiguous only[67]; yet I + find my self indeed inclined to think that they are rather + contiguous (if there be in Nature no other manner of aggregating, + than by the union, or by the touching of the extreams:) and I am + induced thereto by the great difference that I see between the + Conjunction of the parts of an hard or Solid Body[68], and the + Conjunction of the same parts when the same Body shall be made + Liquid and Fluid: for if, for example, I take a Mass of Silver or + other Solid and hard Mettall, I shall in dividing it into two + parts, find not only the resistance that is found in the moving of + it only[69], but an other incomparably greater, dependent on that + vertue, whatever it be, which holds the parts united: and so if we + would divide again those two parts into other two, and successively + into others and others, we should still find a like Resistance, but + ever less by how much smaller the parts to be divided shall be; but + if, lastly, employing most subtile and acute Instruments, such as + are the most tenuous parts of the Fire, we shall resolve it + (perhaps) into its last and least Particles, there shall not be + left in them any longer either Resistance of Division, or so much + as a capacity of being farther divided, especially by Instruments + more grosse than the acuities of Fire: and what Knife or Rasor put + into well melted Silver can we finde, that will divide a thing + which surpasseth the separating power of Fire? Certainly none: + because either the whole shall be reduced to the most minute and + ultimate Divisions, or if there remain parts capable still of other + Subdidivisions, they cannot receive them, but only from acuter + Divisors than Fire; but a Stick or Rod of Iron, moved in the melted + Metall, is not such a one. Of a like Constitution and Consistence, + I account the parts of Water[70], and other Liquids to be, namely, + incapable of Division by reason of their Ienuity; or if not + absolutely indivisible, yet at least not to be divided by a Board, + or other Solid Body, palpable unto the hand, the Sector being + alwayes required to be more sharp than the Solid to be cut. Solid + Bodies, therefore, do only move, and not divide the Water[71], when put + into it; whose parts being before divided to the extreamest + minuity, and therefore capable of being moved, either many of them + at once, or few, or very few, they soon give place to every small + Corpuscle, that descends in the same: for that, it being little and + light, descending in the Air, and arriving to the Surface of the + Water, it meets with Particles of Water more small, and of less + Resistance against Motion and Extrusion, than is its own prement + and extrusive force; whereupon it submergeth, and moveth such a + portion of them, as is proportionate to its Power. There is not, + therefore, any Resistance in Water against Division, nay, there is + not in it any divisible parts. I adde; moreover, that in case yet + there should be any small Resistance found (which is absolutely + false)[72] haply in attempting with an Hair to move a very great natant + Machine, or in essaying by the addition of one small Grain of Lead + to sink, or by removall of it to raise a very broad Plate of + Matter, equall in Gravity with Water, (which likewise will not + happen, in case we proceed with dexterity) we may observe that that + Resistance is a very different thing from that which the + Adversaries produce for the Cause of the Natation of the Plate of + Lead or Board of Ebony, for that one may make a Board of Ebony, + which being put upon the Water swimmeth, and cannot be submerged, + no not by the addition of an hundred Grains of Lead put upon the + same, and afterwards being bathed, not only sinks, though the said + Lead be taken away, but though moreover a quantity of Cork, or of + some other light Body fastened to it, sufficeth not to hinder it + from sinking unto the bottome: so that you see, that although it + were granted that there is a certain small Resistance of Division + found in the substance of the Water, yet this hath nothing to do + with that Cause which supports the Board above the Water, with a + Resistance an hundred times greater than that which men can find in + the parts of the Water: nor let them tell me, that only the Surface + of the Water hath such Resistance[73], and not the internall parts, or + that such Resistance is found greatest in the beginning of the + Submersion, as it also seems that in the beginning, Motion meets + with greater opposition, than in the continuance of it; because, + first, I will permit, that the Water be stirred, and that the + superiour parts be mingled with the middle[74], and inferiour parts, or + that those above be wholly removed, and those in the middle only + made use off, and yet you shall see the effect for all that, to be + still the same: Moreover, that Hair which draws a Beam through the + Water, is likewise to divide the upperparts, and is also to begin + the Motion, and yet it begins it, and yet it divides it: and + finally, let the Board of Ebony be put in the midway, betwixt the + bottome and the top of the Water, and let it there for awhile be + suspended and setled, and afterwards let it be left at liberty, and + it will instantly begin its Motion, and will continue it unto the + bottome. Nay, more, the Board so soon as it is dimitted upon the + Water, hath not only begun to move and divide it, but is for a good + space dimerged into it._ + + [63] The parts of Liquids, so farre from resisting Division, that + they contain not any thing that may be divided. + + [64] The Resistance a Solid findeth in moving through the water, + like to that we meet with in passing through a throng of people: + + [65] Or in thrusting a Stick into an heap of Sand. + + [66] Two kinds of Penetration, one in Bodies continuall, the other + in Bodies only contiguous. + + [67] Water consists not of continuall, but only of contiguous + parts. + + [68] _Se{e} what satisfaction he hath given, as to this point, in + Lib. de Motu. Dial. 2._ + + [69] Great difference betwixt the Conjunction of the parts of a + Body when Solid, and when fluid. + + [70] Water consists of parts that admit of no farther division. + + [71] Solids dimitted into the water, do onely move, and not divide + it. + + [72] If there were any Resistance of Division in water, it must + needs be small, in that it is overcome by an Hair, a Grain of + Lead, or a slight bathing of the Solid. + + [73] The uper parts of the Water, do no more resist Division than + the middle or lower parts. + + [74] Waters Resistance of division, not greater in the beginning + of the Submersion. + +Let us receive it, therefore, for a true and undoubted Conclusion, +That the Water hath not any Renitence against simple Division, and +that it is not possible to find any Solid Body, be it of what Figure +it will, which being put into the Water, its Motion upwards or +downwards, according as it exceedeth, or shall be exceeded by the +Water in Gravity (although such excesse and difference be insensible) +shall be prohibited, and taken away, by the Crassitude of the said +Water. When, therefore, we see the Board of Ebony, or of other Matter, +more grave than the Water, to stay in the Confines of the Water and +Air, without submerging, we must have recourse to some other +Originall, for the investing the Cause of that Effect, than to the +breadth of the Figure, unable to overcome the Renitence with which the +Water opposeth Division, since there is no Resistance; and from that +which is not in being, we can expect no Action. It remains most true, +therefore, as we have said before, that this so succeds, for that that +which in such manner put upon the water, not the same Body with that +which is put _into_ the Water: because this which is put _into_ the +Water, is the pure Board of Ebony, which for that it is more grave +than the Water, sinketh, and that which is put _upon_ the Water, is a +Composition of Ebony, and of so much Air, that both together are +specifically less grave than the Water, and therefore they do not +descend. + +I will farther confirm this which I say. Gentlemen, my Antagonists, we +are agreed, that the excess or defect of the Gravity of the Solid, +unto the Gravity of the Water, is the true and proper Cause of +Natation or Submersion. + + [Sidenote: Great Caution to be had in experimenting the operation + of Figure in Natation.] + +Now, if you will shew that besides the former Cause, there is another +which is so powerfull, that it can hinder and remove the Submersion of +those very Solids, that by their Gravity sink, and if you will say, +that this is the breadth or ampleness of Figure, you are oblieged, +when ever you would shew such an Experiment, first to make the +circumstances certain, that that Solid which you put into the Water, +be not less grave _in specie_ than it, for if you should not do so, +any one might with reason say, that not the Figure, but the Levity was +the cause of that Natation. But I say, that when you shall dimit a +Board of Ebony into the Water, you do not put therein a Solid more +grave _in specie_ than the Water, but one lighter, for besides the +Ebony, there is in the Water a Mass of Air, united with the Ebony, and +such, and so light, that of both there results a Composition less +grave than the Water: See, therefore, that you remove the Air, and put +the Ebony alone into the Water, for so you shall immerge a Solid more +grave then the Water, and if this shall not go to the Bottom, you have +well Philosophized and I ill. + +Now, since we have found the true Cause of the Natation of those +Bodies, which otherwise, as being graver than the Water, would descend +to the bottom, I think, that for the perfect and distinct knowledge of +this business, it would be good to proceed in a way of discovering +demonstratively those particular Accidents that do attend these +effects, and, + + + + +PROBL. I. + + [Sidenote: To finde the proportion Figures ought to have to the + waters Gravity, that by help of the contiguous Air, they may + swim.] + + _To finde what proportion severall Figures of different Matters + ought to have, unto the Gravity of the Water, that so they may be + able by vertue of the Contiguous Air to stay afloat._ + + +[Illustration] + +Let, therefore, for better illustration, D F N E be a Vessell, +wherein the water is contained, and suppose a Plate or Board, whose +thickness is comprehended between the Lines I C and O S, and let it be +of Matter exceeding the water in Gravity, so that being put upon the +water, it dimergeth and abaseth below the Levell of the said water, +leaving the little Banks A I and B C, which are at the greatest height +they can be, so that if the Plate I S should but descend any little +space farther, the little Banks or Ramparts would no longer consist, +but expulsing the Air A I C B, they would diffuse themselves over the +Superficies I C, and would submerge the Plate. The height A I B C is +therefore the greatest profundity that the little Banks of water admit +of. Now I say, that from this, and from the proportion in Gravity, +that the Matter of the Plate hath to the water, we may easily finde of +what thickness, at most, we may make the said Plates, to the end, they +may be able to bear up above water: for if the Matter of the Plate or +Board I S were, for Example, as heavy again as the water, a Board of +that Matter shall be, at the most of a thickness equall to the +greatest height of the Banks, that is, as thick as A I is high: which +we will thus demonstrate. Let the Solid I S be double in Gravity to +the water, and let it be a regular Prisme, or Cylinder, to wit, that +hath its two flat Superficies, superiour and inferiour, alike and +equall, and at Right Angles with the other laterall Superficies, and +let its thickness I O be equall to the greatest Altitude of the Banks +of water: I say, that if it be put upon the water, it will not +submerge: for the Altitude A I being equall to the Altitude I O, the +Mass of the Air A B C I shall be equall to the Mass of the Solid C I O +S: and the whole Mass A O S B double to the Mass I S; And since the +Mass of the Air A C, neither encreaseth nor diminisheth the Gravity of +the Mass I S, and the Solid I S was supposed double in Gravity to the +water; Therefore as much water as the Mass submerged A O S B, +compounded of the Air A I C B, and of the Solid I O S C, weighs just +as much as the same submerged Mass A O S B: but when such a Mass of +water, as is the submerged part of the Solid, weighs as much as the +said Solid, it descends not farther, but resteth, as by (_a_) +_Archimedes_[75], and above by us, hath been demonstrated: Therefore, I S +shall descend no farther, but shall rest. And if the Solid I S shall +be Sesquialter in Gravity to the water, it shall float, as long as its +thickness be not above twice as much as the greatest Altitude of the +Ramparts of water, that is, of A I. For I S being Sesquialter in +Gravity to the water, and the Altitude O I, being double to I A, the +Solid submerged A O S B, shall be also Sesquialter in Mass to the +Solid I S. And because the Air A C, neither increaseth nor diminisheth +the ponderosity of the Solid I S: Therefore, as much water in quantity +as the submerged Mass A O S B, weighs as much as the said Mass +submerged: And, therefore, that Mass shall rest. And briefly in +generall. + + [75] Of Natation Lib. 1. Prop. 3. + +[Illustration] + + + + +THEOREME. VI. + + [Sidenote: The proportion of the greatest thickness of Solids, + beyond which encreased they sink.] + + _When ever the excess of the Gravity of the Solid above the Gravity + of the Water, shall have the same proportion to the Gravity of + the Water, that the Altitude of the Rampart, hath to the + thickness of the Solid, that Solid shall not sink, but being + never so little thicker it shall._ + + +[Illustration] + +Let the Solid I S be superior in Gravity to the water, and of such +thickness, that the Altitude of the Rampart A I, be in proportion to +the thickness of the Solid I O, as the excess of the Gravity of the +said Solid I S, above the Gravity of a Mass of water equall to the +Mass I S, is to the Gravity of the Mass of water equall to the Mass I +S. I say, that the Solid I S shall not sinke, but being never so +little thicker it shall go to the bottom: For being that as A I is to +I O, so is the Excess of the Gravity of the Solid I S, above the +Gravity of a Mass of water equall to the Mass I S, to the Gravity of +the said Mass of water: Therefore, compounding, as A O is to O I, so +shall the Gravity of the Solid I S, be to the Gravity of a Mass of +water equall to the Mass I S: And, converting, as I O is to O A, so +shall the Gravity of a Mass of water equall to the Mass I S, be to the +Gravity of the Solid I S: But as I O is to O A, so is a Mass of water +I S, to a Mass of water equall to the Mass A B S O: and so is the +Gravity of a Mass of water I S, to the Gravity of a Mass of water A S: +Therefore as the Gravity of a Mass of water, equall to the Mass I S, +is to the Gravity of the Solid I S, so is the same Gravity of a Mass +of water I S, to the Gravity of a Mass of Water A S: Therefore the +Gravity of the Solid I S, is equall to the Gravity of a Mass of water +equall to the Mass A S: But the Gravity of the Solid I S, is the same +with the Gravity of the Solid A S, compounded of the Solid I S, and of +the Air A B C I. Therefore the whole compounded Solid A O S B, weighs +as much as the water that would be comprised in the place of the said +Compound A O S B: And, therefore, it shall make an _Equilibrium_ and +rest, and that same Solid I O S C shall sinke no farther. But if its +thickness I O should be increased, it would be necessary also to +encrease the Altitude of the Rampart A I, to maintain the due +proportion: But by what hath been supposed, the Altitude of the +Rampart A I, is the greatest that the Nature of the Water and Air do +admit, without the waters repulsing the Air adherent to the +Superficies of the Solid I C, and possessing the space A I C B: +Therefore, a Solid of greater thickness than I O, and of the same +Matter with the Solid I S, shall not rest without submerging, but +shall descend to the bottome: which was to be demonstrated. In +consequence of this that hath been demonstrated, sundry and various +Conclusions may be gathered, by which the truth of my principall +Proposition comes to be more and more confirmed, and the imperfection +of all former Argumentations touching the present Question cometh to +be discovered. + +_And first we gather from the things demonstrated, that,_ + + + + +THEOREME VII. + + [Sidenote: The heaviest Bodies may swimme.] + + _All Matters, how heavy soever, even to Gold it self, the heaviest + of all Bodies, known by us, may float upon the Water._ + + +Because its Gravity being considered to be almost twenty times greater +than that of the water, and, moreover, the greatest Altitude that the +Rampart of water can be extended to, without breaking the Contiguity +of the Air, adherent to the Surface of the Solid, that is put upon the +water being predetermined, if we should make a Plate of Gold so thin, +that it exceeds not the nineteenth part of the Altitude of the said +Rampart, this put lightly upon the water shall rest, without going to +the bottom: and if Ebony shall chance to be in sesquiseptimall +proportion more grave than the water, the greatest thickness that can +be allowed to a Board of Ebony, so that it may be able to stay above +water without sinking, would be seaven times more than the height of +the Rampart Tinn, _v. gr._ eight times more grave than water, shall +swimm as oft as the thickness of its Plate, exceeds not the 7th part +of the Altitude of the Rampart. + + [Sidenote: _He elsewhere cites this as a Proposition, therefore I + make it of that number._] + +And here I will not omit to note, as a second Corrollary dependent +upon the things demonstrated, that, + + + + +THEOREME VIII. + + [Sidenote: Natation and Submersion, collected from the thickness, + excluding the length and breadth of Plates.] + + _The Expansion of Figure not only is not the Cause of the Natation + of those grave Bodies, which otherwise do submerge, but also the + determining what be those Boards of Ebony, or Plates of Iron or + Gold that will swimme, depends not on it, rather that same + determination is to be collected from the only thickness of those + Figures of Ebony or Gold, wholly excluding the consideration of + length and breadth, as having no wayes any share in this Effect._ + + +It hath already been manifested, that the only cause of the Natation +of the said Plates, is the reduction of them to be less grave than the +water, by means of the connexion of that Air, which descendeth +together with them, and possesseth place in the water; which place so +occupyed, if before the circumfused water diffuseth it self to fill +it, it be capable of as much water, as shall weigh equall with the +Plate, the Plate shall remain suspended, and sinke no farther. + +Now let us see on which of these three dimensions of the Solid +depends the terminating, what and how much the Mass of that ought to +be, that so the assistance of the Air contiguous unto it, may suffice +to render it specifically less grave than the water, whereupon it may +rest without Submersion. It shall undoubtedly be found, that the +length and breadth have not any thing to do in the said determination, +but only the height, or if you will the thickness: for, if we take a +Plate or Board, as for Example, of Ebony, whose Altitude hath unto the +greatest possible Altitude of the Rampart, the proportion above +declared, for which cause it swims indeed, but yet not if we never so +little increase its thickness; I say, that retaining its thickness, +and encreasing its Superficies to twice, four times, or ten times its +bigness, or dminishing it by dividing it into four, or six, or twenty, +or a hundred parts, it shall still in the same manner continue to +float: but encreasing its thickness only a Hairs breadth, it will +alwaies submerge, although we should multiply the Superficies a +hundred and a hundred times. Now forasmuch as that this is a Cause, +which being added, we adde also the Effect, and being removed, it is +removed; and by augmenting or lessening the length or breadth in any +manner, the effect of going, or not going to the bottom, is not added +or removed: I conclude, that the greatness and smalness of the +Superficies hath no influence upon the Natation or Submersion. And +that the proportion of the Altitude of the Ramparts of Water, to the +Altitude of the Solid, being constituted in the manner aforesaid, the +greatness or smalness of the Superficies, makes not any variation, is +manifest from that which hath been above demonstrated, and from this, +that, _The Prisms and Cylinders which have the same Base, are in +proportion to one another as their heights._ Whence Cylinders or +Prismes[76], namely, the Board, be they great or little, so that they be +all of equall thickness, have the same proportion to their +Conterminall Air, which hath for Base the said Superficies of the +Board, and for height the Ramparts of water; so that alwayes of that +Air, and of the Board, Solids, are compounded, that in Gravity equall +a Mass of water equall to the Mass of the Solids, compounded of Air, +and of the Board: whereupon all the said Solids do in the same manner +continue afloat. We will conclude in the third place, that, + + [76] Prismes and Cylinders having the same Base, are to one + another as their heights. + + + + +THEOREME. IX. + + [Sidenote: All Figures of all Matters, float by hep of the + Rampart replenished with Air, and some but only touch the water.] + + _All sorts of Figures of whatsoever Matter, albeit more grave than + the Water, do by Benefit of the said Rampart, not only float, but + some Figures, though of the gravest Matter, do stay wholly above + Water, wetting only the inferiour Surface that toucheth the + Water._ + + +And these shall be all Figures, which from the inferiour Base upwards, +grow lesser and lesser; the which we shall exemplifie for this time in +Piramides or Cones, of which Figures the passions are common. We will +demonstrate therefore, that, + + _It is possible to form a Piramide, of any whatsoever Matter + preposed, which being put with its Base upon the Water, rests not + only without submerging, but without wetting it more then its + Base._ + +For the explication of which it is requisite, that we first +demonstrate the subsequent Lemma, namely, that, + + + + +LEMMA II. + + [Sidenote: Solids whose Masses are in contrary proportion to + their Specifick Gravities are equall in absolute Gravity.] + + _Solids whose Masses answer in proportion contrarily to their + Specificall Gravities, are equall in Absolute Gravities._ + + +[Illustration] + +Let A C and B be two Solids, and let the Mass A C be to the Mass B, +as the Specificall Gravity of the Solid B, is to the Specificall +Gravity of the Solid A C: I say, the Solids A C and B are equall in +absolute weight, that is, equally grave. For if the Mass A C be equall +to the Mass B, then, by the Assumption, the Specificall Gravity of B, +shall be equall to the Specificall Gravity of A C, and being equall in +Mass, and of the same Specificall Gravity they shall absolutely weigh +one as much as another. But if their Masses shall be unequall, let the +Mass A C be greater, and in it take the part C, equall to the Mass B. +And, because the Masses B and C are equall; the Absolute weight of B, +shall have the same proportion to the Absolute weight of C, that the +Specificall Gravity of B, hath to the Specificall Gravity of C; or of +C A, which is the same _in specie_: But look what proportion the +Specificall Gravity of B, hath to the Specificall Gravity of C A, the +like proportion, by the Assumption, hath the Mass C A, to the Mass B, +that is, to the Mass C: Therefore, the absolute weight of B, to the +absolute weight of C, is as the Mass A C to the Mass C: But as the +Mass A C, is to the Mass C, so is the absolute weight of A C, to the +absolute weight of C: Therefore the absolute weight of B, hath the +same proportion to the absolute weight of C, that the absolute weight +of A C, hath to the absolute weight of C: Therefore, the two Solids A +C and B are equall in absolute Gravity: which was to be demonstrated. +Having demonstrated this, I say, + + + + +THEOREME X. + + [Sidenote: There may be Cones and Piramides of any Matter, which + demitted into the water, rest only their Bases.] + + _That it is possible of any assigned Matter, to form a Piramide or + Cone upon any Base, which being put upon the Water shall not + submerge, nor wet any more than its Base._ + + +[Illustration] + +Let the greatest possible Altitude of the Rampart be the Line D B, +and the Diameter of the Base of the Cone to be made of any Matter +assigned B C, at right angles to D B: And as the Specificall Gravity +of the Matter of the Piramide or Cone to be made, is to the +Specificall Gravity of the water, so let the Altitude of the Rampart D +B, be to the third part of the Piramide or Cone A B C, described upon +the Base, whose Diameter is B C: I say, that the said Cone A B C, and +any other Cone, lower then the same, shall rest upon the Surface of +the water B C without sinking. Draw D F parallel to B C, and suppose +the Prisme or Cylinder E C, which shall be tripple to the Cone A B C. +And, because the Cylinder D C hath the same proportion to the Cylinder +C E, that the Altitude D B, hath to the Altitude B E: But the Cylinder +C E, is to the Cone A B C, as the Altitude E B is to the third part of +the Altitude of the Cone: Therefore, by Equality of proportion, the +Cylinder D C is to the Cone A B C, as D B is to the third part of the +Altitude B E: But as D B is to the third part of B E, so is the +Specificall Gravity of the Cone A B C, to the Specificall Gravity of +the water: Therefore, as the Mass of the Solid D C, is to the Mass of +the Cone A _B_ C, so is the Specificall Gravity of the said Cone, to +the Specificall Gravity of the water: Therefore, by the precedent +Lemma, the Cone A B C weighs in absolute Gravity, as much as a Mass of +Water equall to the Mass D C: But the water which by the imposition of +the Cone A B C, is driven out of its place, is as much as would +precisely lie in the place D C, and is equall in weight to the Cone +that displaceth it: Therefore, there shall be an _Equilibrium_, and +the Cone shall rest without farther submerging. And its manifest, + + +COROLARY I. + + [Sidenote: Amongst Cones of the same Base, those of least + Altitude shall sink the least.] + + _That making upon the same Basis, a Cone of a less Altitude, it + shall be also less grave, and shall so much the more rest without + Submersion._ + + +COROLARY II. + + [Sidenote: There may be Cones and Piramides of any Matter, which + demitted with the Point downwards do float atop.] + + _It is manifest, also, that one may make Cones and Piramids of any + Matter whatsoever, more grave than the water, which being put + into the water, with the Apix or Point downwards, rest without + Submersion._ + +Because if we reassume what hath been above demonstrated, of Prisms +and Cylinders, and that on Bases equall to those of the said +Cylinders, we make Cones of the same Matter, and three times as high +as the Cylinders, they shall rest afloat, for that in Mass and Gravity +they shall be equall to those Cylinders, and by having their Bases +equall to those of the Cylinders, they shall leave equall Masses of +Air included within the Ramparts. This, which for Example sake hath +been demonstrated, in Prisms, Cylinders, Cones and Piramids, might be +proved in all other Solid Figures, but it would require a whole Volume +(such is the multitude and variety of their Symptoms and Accidents) to +comprehend the particuler demonstration of them all, and of their +severall Segments: but I will to avoid prolixity in the present +Discourse, content my self, that by what I have declared every one of +ordinary Capacity may comprehend, that there is not any Matter so +grave, no not Gold it self, of which one may not form all sorts of +Figures, which by vertue of the superiour Air adherent to them, and +not by the Waters Resistance of Penetration, do remain afloat, so that +they sink not. Nay, farther, I will shew, for removing that Error, +that, + + + + +THEOREME XI. + + [Sidenote: A Piramide or Cone, demitted with the Point downwards + shal swim, with its Base downward shall sink.] + + _A Piramide or Cone put into the Water, with the Point downward + shall swimme, and the same put with the Base downwards shall + sinke, and it shall be impossible to make it float._ + + +Now the quite contrary would happen, if the difficulty of Penetrating +the water, were that which had hindred the descent, for that the said +Cone is far apter to pierce and penetrate with its sharp Point, than +with its broad and spacious Base. + +And, to demonstrate this, let the Cone be _A B C_, twice as grave as +the water, and let its height be tripple to the height of the Rampart +_D A E C_: I say, first, that being put lightly into the water with +the Point downwards, it shall not descend to the bottom: for the +Aeriall Cylinder contained betwixt the Ramparts _D A C E_, is equall +in Mass to the Cone _A B C_; so that the whole Mass of the Solid +compounded of the Air _D A C E_, and of the Cone _A B C_, shall be +double to the Cone _A C B_: And, because the Cone _A B C_ is supposed +to be of Matter double in Gravity to the water, therefore as much +water as the whole Masse _D A B C E_, placed beneath the Levell of the +water, weighs as much as the Cone _A B C_: and, therefore, there shall +be an _Equilibrium_, and the Cone _A B C_ shall descend no lower. Now, +I say farther, that the same Cone placed with the Base downwards, +shall sink to the bottom, without any possibility of returning again, +by any means to swimme. + +[Illustration] + +Let, therefore, the Cone be _A B D_, double in Gravity to the water, +and let its height be tripple the height of the Rampart of water L B: +It is already manifest, that it shall not stay wholly out of the +water, because the Cylinder being comprehended betwixt the Ramparts _L +B D P_, equall to the Cone _A B D_, and the Matter of the Cone, beig +double in Gravity to the water, it is evident that the weight of the +said Cone shall be double to the weight of the Mass of water equall to +the Cylinder _L B D P_: Therefore it shall not rest in this state, but +shall descend. + +[Illustration] + + +COROLARY I. + + [Sidenote: Much less shall the said Cone swim, if one immerge a + part thereof.] + + _I say farther; that much lesse shall the said Cone stay afloat, if + one immerge a part thereof._ + +Which you may see, comparing with the water as well the part that +shall immerge as the other above water. Let us therefore of the Cone A +B D, submergeth part N T O S, and advance the Point N S F above water. +The Altitude of the Cone F N S, shall either be more than half the +whole Altitude of the Cone F T O, or it shall not be more: if it shall +be more than half, the Cone F N S shall be more than half of the +Cylinder E N S C: for the Altitude of the Cone F N S, shall be more +than Sesquialter of the Altitude of the Cylinder E N S C: And, because +the Matter of the Cone is supposed to be double in Specificall Gravity +to the water, the water which would be contained within the Rampart E +N S C, would be less grave absolutely than the Cone F N S; so that the +whole Cone F N S cannot be sustained by the Rampart: But the part +immerged N T O S, by being double in Specificall Gravity to the water, +shall tend to the bottom: Therefore, the whole _C_one F T O, as well +in respect of the part submerged, as the part above water shall +descend to the bottom. But if the Altitude of the Point F N S, shall +be half the Altitude of the whole Cone F T O, the same Altitude of the +said Cone F N S shall be Sesquialter to the Altitude E N: and, +therefore, E N S C shall be double to the Cone F N S; and as much +water in Mass as the _C_ylinder E N S C, would weigh as much as the +part of the _C_one F N S. But, because the other immerged part N T O +S, is double in Gravity to the water, a Mass of water equall to that +compounded of the _C_ylinder E N S C, and of the Solid N T O S, shall +weigh less than the _C_one F T O, by as much as the weight of a Mass +of water equall to the Solid N T O S: Therefore, the _C_one sha{l}l +also descend. Again, because the Solid N T O S, is septuple to the +Cone F N S, to which the _C_ylinder E S is double, the proportion of +the Solid N T O S, shall be to the _C_ylinder E N S C, as seaven to +two: Therefore, the whole Solid compounded of the _C_ylinder E N S C, +and of the Solid N T O S, is much less than double the Solid N T O S: +Therefore, the single Solid N T O S, is much graver than a Mass of +water equall to the Mass, compounded of the _C_ylinder E N S C, and of +N T O S. + + +COROLARY II. + + [Sidenote: Part of the Cones towards the Cuspis removed, it shall + still sink.] + + _From whence it followeth, that though one should remove and take + away the part of the Cone F N S, the sole remainder N T O S would + go to the bottom._ + + +COROLARY III. + + [Sidenote: The more the Cone is immerged, the more impossible is + its floating.] + + _And if we should more depress the Cone F T O, it would be so much + the more impossible that it should sustain it self afloat, the + part submerged N T O S still encreasing, and the Mass of Air + contained in the Rampart diminishing, which ever grows less, the + more the Cone submergeth._ + +That Cone, therefore, that with its Base upwards, and its _Cuspis_ +downwards doth swimme, being dimitted with its Base downward must of +necessity sinke. They have argued farre from the truth, therefore, who +have ascribed the cause of Natation to waters resistance of Division, +as to a passive principle, and to the breadth of the Figure, with +which the division is to be made, as the Efficient. + +I come in the fourth place, to collect and conclude the reason of +that which I have proposed to the Adversaries, namely, + + + + +THEOREME XII. + + [Sidenote: Solids of any Figure & greatnesse, that naturally + sink, may by help of the Air in the Rampart swimme.] + + _That it is possible to fo{r}m Solid Bodies, of what Figure and + greatness soever, that of their own Nature goe to the Bottome; + But by the help of the Air contained in the Rampart, rest without + submerging._ + + +[Illustration] + +The truth of this Proposition is sufficiently manifest in all those +Solid Figures, that determine in their uppermost part in a plane +Superficies: for making such Figures of some Matter specifically as +grave as the water, putting them into the water, so that the whole +Mass be covered, it is manifest, that they shall rest in all places, +provided, that such a Matter equall in weight to the water, may be +exactly adjusted: and they shall by consequence, rest or lie even with +the Levell of the water, without making any Rampart. If, therefore, in +respect of the Matter, such Figures are apt to rest without +submerging, though deprived of the help of the Rampart, it is +manifest, that they may admit so much encrease of Gravity, (without +encreasing their Masses) as is the weight of as much water as would be +contained within the Rampart, that is made about their upper plane +Surface: by the help of which being sustained, they shall rest afloat, +but being bathed, they shall descend, having been made graver than the +water. In Figures, therefore, that determine above in a plane, we may +cleerly comprehend, that the Rampart added or removed, may prohibit or +permit the descent: but in those Figures that go lessening upwards +towards the top, some Persons may, and that not without much seeming +Reason, doubt whether the same may be done, and especially by those +which terminate in a very acute Point, such as are your Cones and +small Piramids. Touching these, therefore, as more dubious than the +rest, I will endeavour to demonstrate, that they also lie under the +same Accident of going, or not going to the Bottom, be they of any +whatever bigness. Let therefore the Cone be A B D, made of a matter +specifically as grave as the water; it is manifest that being put all +under water, it shall rest in all places (alwayes provided, that it +shall weigh exactly as much as the water, which is almost impossible +to effect) and that any small weight being added to it, it shall sink +to the bottom: but if it shall descend downwards gently, I say, that +it shall make the Rampart E S T O, and that there shall stay out of +the water the point A S T, tripple in height to the Rampart E S: which +is manifest, for the Matter of the Cone weighing equally with the +water, the part submerged _S B D T_, becomes indifferent to move +downwards or upwards; and the Cone _A S T_, being equall in Mass to +the water that would be contained in the concave of the Rampart _E S T +O_, shall be also equall unto it in Gravity: and, therefore, there +shall be a perfect _Equilibrium_, and, consequently, a Rest. Now here +ariseth a doubt, whether the Cone _A B D_ may be made heavier, in such +sort, that when it is put wholly under water, it goes to the bottom, +but yet not in such sort, as to take from the Rampart the vertue of +sustaining it that it sink not, and, the reason of the doubt is this: +that although at such time as the Cone _A B D_ is specifically as +grave as the water, the Rampart _E S T O_ sustaines it, not only when +the point _A S T_ is tripple in height to the Altitude of the Rampart +_E S_, but also when a lesser part is above water; [for although in +the Descent of the Cone the Point _A S T_ by little and little +diminisheth, and so likewise the Rampart _E S T O_, yet the Point +diminisheth in greater proportion than the Rampart, in that it +diminisheth according to all the three Dimensions, but the Rampart +according to two only, the Altitude still remaining the same; or, if +you will, because the Cone _S {A} T_ goes diminishing, according to +the proportion of the cubes of the Lines that do successively become +the Diameters of the Bases of emergent Cones, and the Ramparts +diminish according to the proportion of the Squares of the same Lines; +whereupon the proportions of the Points are alwayes Sesquialter of the +proportions of the Cylinders, contained within the Rampart; so that +if, for Example, the height of the emergent Point were double, or +equall to the height of the Rampart, in these cases, the Cylinder +contained within the Rampart, would be much greater than the said +Point, because it would be either sesquialter or tripple, by reason of +which it would perhaps serve over and above to sustain the whole Cone, +since the part submerged would no longer weigh any thing;] yet, +nevertheless, when any Gravity is added to the whole Mass of the Cone, +so that also the part submerged is not without some excesse of Gravity +above the Gravity of the water, it is not manifest, whether the +Cylinder contained within the Rampart, in the descent that the Cone +shall make, can be reduced to such a proportion unto the emergent +Point, and to such an excesse of Mass above the Mass of it, as to +compensate the excesse of the Cones Specificall Gravity above the +Gravity of the water: and the Scruple ariseth, because that howbeit in +the descent made by the Cone, the emergent Point _A S T_ diminisheth, +whereby there is also a diminution of the excess of the Cones Gravity +above the Gravity of the water, yet the case stands so, that the +Rampart doth also contract it self, and the Cylinder contained in it +doth deminish. Nevertheless it shall be demonstrated, how that the +Cone _A B D_ being of any supposed bignesse, and made at the first of +a Matter exactly equall in Gravity to the Water, if there may be +affixed to it some Weight, by means of which i{t} may descend to the +bottom, when submerged under water, it may also by vertue of the +Rampart stay above without sinking. + +[Illustration] + +[Illustration] + +Let, therefore, the Cone _A B D_ be of any supposed greatnesse, and +alike in specificall Gravity to the water. It is manifest, that being +put lightly into the water, it shall rest without descending; and it +shall advance above water, the Point _A S T_, tripple in height to the +height of the Rampart _E S_: Now, suppose the Cone _A B D_ more +depressed, so that it advance above water, only the Point _A I R_, +higher by half than the Point _A S T_, with the Rampart about it _C I +R N_. And, because, the Cone _A B D_ is to the Cone _A I R_, as the +cube of the Line _S T_ is to the cube of the Line _I R_, but the +Cylinder _E S T O_, is to the Cylinder _C I R N_, as the Square of _S +T_ to the Square of _I R_, the Cone _A S T_ shall be Octuple to the +Cone _A I R_, and the Cylinder _E S T O_, quadruple to the Cylinder _C +I R N_: But the Cone _A S T_, is equall to the Cylinder _E S T O_: +Therefore, the Cylinder _C I R N_, shall be double to the Cone _A I +R_: and the water which might be contained in the Rampart _C I R N_, +would be double in Mass and in Weight to the Cone _A I R_, and, +therefore, would be able to sustain the double of the Weight of the +Cone _A I R_: Therefore, if to the whole Cone _A B D_, there be added +as much Weight as the Gravity of the Cone _A I R_, that is to say, the +eighth part of the weight of the Cone _A S T_, it also shall be +sustained by the Rampart _C I R N_, but without that it shall go to +the bottome: the Cone _A B D_, being, by the addition of the eighth +part of the weight of the Cone _A S T_, made specifically more grave +than the water. But if the Altitude of the Cone _A I R_, were two +thirds of the Altitude of the Cone _A S T_, the Cone _A S T_ would be +to the Cone _A I R_, as twenty seven to eight; and the Cylinder _E S T +O_, to the Cylinder _C I R N_, as nine to four, that is, as twenty +seven to twelve; and, therefore, the Cylinder _C I R N_, to the Cone +_A I R_, as twelve to eight; and the excess of the Cylinder _C I R N_, +above the Cone _A I R_, to the Cone _A S T_, as four to twenty seven: +therefore if to the Cone _A B D_ be added so much weight as is the +four twenty sevenths of the weight of the Cone _A S T_, which is a +little more then its seventh part, it also shall continue to swimme, +and the height of the emergent Point shall be double to the height of +the Rampart. This that hath been demonstrated in Cones, exactly holds +in Piramides, although the one or the other should be very sharp in +their Point or Cuspis[77]: From whence we conclude, that the same Accident +shall so much the more easily happen in all other Figures, by how much +the less sharp the Tops shall be, in which they determine, being +assisted by more spacious Ramparts. + + [77] Natatio{n} easiest effected in Figures broad toward the top. + + + + +THEOREME XIII. + + [Sidenote: All Figures sink or swim, upon bathing or not bathing + of their tops.] + + _All Figures, therefore, of whatever greatnesse, may go, and not + go, to the Bottom, according as their Sumities or Tops shall be + bathed or not bathed._ + + +And this Accident being common to all sorts of Figures, without +exception of so much as one. Figure hath, therefore, no part in the +production of this Effect, of sometimes sinking, and sometimes again +not sinking, but only the being sometimes conjoyned to, and sometimes +seperated from, the supereminent Air: which cause, in fine, who so +shall rightly, and, as we say, with both his Eyes, consider this +business, will find that it is reduced to, yea, that it really is the +same with, the true, Naturall and primary cause of Natation or +Submersion; to wit, the excess or deficiency of the Gravity of the +water, in relation to the Gravity of that Solid Magnitude, that is +demitted into the water. For like as a Plate of Lead, as thick as the +back of a Knife, which being put into the water by it self alone goes +to the bottom, if upon it you fasten a piece of Cork four fingers +thick, doth continue afloat, for that now the Solid that is demitted +in the water, is not, as before, more grave than the water, but less, +so the Board of Ebony, of its own nature more grave than water; and, +therefore, descending to the bottom, when it is demitted by it self +alone into the water, if it shall be put upon the water, conjoyned +with an Expanded vail of Air, that together with the Ebony doth +descend, and that it be such, as that it doth make with it a compound +less grave than so much water in Mass, as equalleth the Mass already +submerged and depressed beneath the Levell of the waters Surface, it +shall not descend any farther, but shall rest, for no other than the +universall and most common cause, which is that Solid Magnitudes, less +grave _in specie_ than the water, go not to the bottom. + +So that if one should take a Plate of Lead, as for Example, a finger +thick, and an handfull broad every way, and should attempt to make it +swimme, with putting it lightly on the water, he would lose his +Labour, because that if it should be depressed an Hairs breadth beyond +the possible Altitude of the Ramparts of water, it would dive and +sink; but if whilst it is going downwards, one should make certain +Banks or Ramparts about it, that should hinder the defusion of the +water upon the said Plate, the which Banks should rise so high, as +that they might be able to contain as much water, as should weigh +equally with the said Plate, it would, witho{u}t all Question, descend +no lower, but would rest, as being sustained by vertue of the Air +contained within the aforesaid Ramparts: and, in short, there would be +a Vessell by this means formed with the bottom of Lead. But if the +thinness of the Lead shall be such, that a very small height of +Rampart would suffice to contain so much Air, as might keep it afloat, +it shall also rest without the Artificiall Banks or Ramparts, but yet +not without the Air, because the Air by it self makes Banks sufficient +for a small height, to resist the Superfusion of the water: so that +that which in this case swimmes, is as it were a Vessell filled with +Air, by vertue of which it continueth afloat. + +I will, in the last place, with an other Experime{n}t, attempt to +remove all difficulties, if so be there should yet be any doubt left +in any one, touching the opperation of this [E]Continuity of the Air, +with the thin Plate which swims, and afterwards put an end to this +part of my discourse. + + [E] Or rather Contiguity, + +I suppose my self to be questioning with some of my Oponents. + +Whether Figure have any influence upon the encrease or diminution of +the Resistance in any Weight against its being raised in the Air[78]; and +I suppose, that I am to maintain the Affirmative, asserting that a +Mass of Lead, reduced to the Figure of a Ball, shall be raised with +less force, then if the same had been made into a thinne and broad +Plate, because that it in this spacious Figure, hath a great quantity +of Air to penetrate, and in that other, more compacted and contracted +very little: and to demonstrate the truth of such my Opinion, I will +hang in a small thred first the Ball or Bullet, and put that into the +water, tying the thred that upholds it to one end of the Ballance that +I hold in the Air, and to the other end I by degrees adde so much +Weight, till that at last it brings up the Ball of Lead out of the +water: to do which, suppose a Gravity of thirty Ounces sufficeth; I +afterwards reduce the said Lead into a flat and thinne Plate, the +which I likewise put into the water, suspended by three threds, which +hold it parallel to the Surface of the water, and putting in the same +manner, Weights to the other end, till such time as the Plate comes to +be raised and drawn out of the water: I finde that thirty six ounces +will not suffice to seperate it from the water, and raise it thorow +the Air: and arguing from this Experiment, I affirm, that I have fully +demonstrated the truth of my Proposition. Here my Oponents desires me +to look down, shewing me a thing which I had not before observed, to +wit, that in the Ascent of the Plate out of the water, it draws after +it another Plate (_if I may so call it_) of water, which before it +divides and parts from the inferiour Surface of the Plate of Lead, is +raised above the Levell of the other water, more than the thickness of +the back of a Knife: Then he goeth to repeat the Experiment with the +Ball, and makes me see, that it is but a very small quantity of water, +which cleaves to its compacted and contracted Figure: and then he +subjoynes, that its no wonder, if in seperating the thinne and broad +Plate from the water, we meet with much greater Resistance, than in +seperating the Ball, since together with the Plate, we are to raise a +great quantity of water, which occurreth not in the Ball: He telleth +me moreover, how that our Question is, whether the Resistance of +Elevation be greater in a dilated Plate of Lead, than in a Ball, and +not whether more resisteth a Plate of Lead with a great quantity of +water, or a Ball with a very little water: He sheweth me in the close, +that the putting the Plate and the Ball first into the water, to make +proofe thereby of their Resistance in the Air, is besides our case, +which treats of Elivating in the Air, and of things placed in the Air, +and not of the Resistance that is made in the Confines of the Air and +water, and by things which are part in Air and part in water: and +lastly, they make me feel with my hand, that when the thinne Plate is +in the Air, and free from the weight of the water, it is raised with +the very same Force that raiseth the Ball. Seeing, and understanding +these things, I know not what to do, unless to grant my self +convinced, and to thank such a Friend, for having made me to see that +which I never till then observed: and, being advertised by this same +Accident, to tell my Adversaries, that our Question is, whether a +Board and a Ball of Ebony, equally go to the bottom in water, and not +a Ball of Ebony and a Board of Ebony, joyned with another flat Body of +Air: and, farthermore, that we speak of sinking, and not sinking to +the bottom, in water, and not of that which happeneth in the Confines +of the water and Air to Bodies that be part in the Air, and part in +the water; nor much less do we treat of the greater or lesser Force +requisite in seperating this or that Body from the Air; not omitting +to tell them, in the last place, that the Air doth resist, and +gravitate downwards in the water, just so much as the water (if I may +so speak) gravitates and resists upwards in the Air, and that the same +Force is required to sinke a Bladder under water, that is full of Air, +as to raise it in the Air, being full of water, removing the +consideration of the weight of that Filme or Skinne, and considering +the water and the Air only. And it is likewise true, that the same +Force is required to sink a Cup or such like Vessell under water, +whilst it is full of Air, as to raise it above the Superficies of the +water, keeping it with the mouth downwards; whilst it is full of +water, which is constrained in the same manner to follow the Cup which +contains it, and to rise above the other water into the Region of the +Air, as the Air is forced to follow the same Vessell under the Surface +of the water, till that in this c{a}se the water, surmounting the +brimme of the Cup, breaks in, driving thence the Air, and in that +case, the said brimme coming out of the water, and arriving to the +Confines of the Air, the water falls down, and the Air sub-enters to +fill the cavity of the Cup: upon which ensues, that he no less +transgresses the Articles of the _Convention_, who produceth a Plate +conjoyned with much Air, to see if it descend to the bottom in water, +then he that makes proof of the Resistance against Elevation in Air +with a Plate of Lead, joyned with a like quantity of water. + + [78] An Experiment of the operation of Figures, in encreasing or + lessening of the Airs Resistance of Division. + + [Sidenote: _Aristotles_ opinion touching the Operation of Figure + examined.] + +I have said all that I could at present think of, to maintain the +Assertion I have undertook. It remains, that I examine that which +_Aristotle_ hath writ of this matter towards the end of his Book De +Caelo[79]; wherein I shall note two things: the one that it being true as +hath been demonstrated, that Figure hath nothing to do about the +moving or not moving it self upwards or downwards, its seemes that +_Aristotle_ at his first falling upon this Speculation, was of the +same opinion, as in my opinion may be collected from the examination +of his words. 'Tis true, indeed, that in essaying afterwards to render +a reason of such effect, as not having in my conceit hit upon the +right, (which in the second place I will examine) it seems that he is +brought to admit the largenesse of Figure, to be interessed in this +operation. As to the first particuler, hear the precise words of +_Aristotle_. + + [79] _Aristot. de Caelo_ Lib. 4. Cap 6. + +_Figures are not the Causes of moving simply upwards or downwards, but +of moving more slowly or swiftly[80][81], and by what means this comes to +pass, it is not difficult to see._ + + [80] _Aristotle_ makes not Figure the cause of Motion absolutely, + but of swift or slow motion, + + [81] Lib. 4. Cap. 6: Text. 42. + +Here first I note, that the terms being four, which fall under the +present consideration, namely, Motion, Rest, Slowly and Swiftly: And +_Aristotle_ naming figures as Causes of Tardity and Velocity, +excluding them from being the Cause of absolute and simple Motion, it +seems necessary, that he exclude them on the other side, from being +the Cause of Rest, so that his meaning is this. Figures are not the +Causes of moving or not moving absolutely, but of moving quickly or +slowly: and, here, if any should say the mind of _Aristotle_ is to +exclude Figures from being Causes of Motion, but yet not from being +Causes of Rest, so that the sence would be to remove from Figures, +there being the Causes of moving simply, but yet not there being +Causes of Rest, I would demand, whether we ought with _Aristotle_ to +understand, that all Figures universally, are, in some manner, the +causes of Rest in those Bodies, which otherwise would move, or else +some particular Figures only, as for Example, broad and thinne +Figures: If all indifferently, then every Body shall rest: because +every Body hath some Figure, which is false; but if some particular +Figures only may be in some manner a Cause of Rest, as, for Example, +the broad, then the others would be in some manner the Causes of +Motion: for if from seeing some Bodies of a contracted Figure move, +which after dilated into Plates rest, may be inferred, that the +Amplitude of Figure hath a part in the Cause of that Rest; so from +seeing such like Figures rest, which afterwards contracted move, it +may with the same reason be affirmed, that the united and contracted +Figure, hath a part in causing Motion, as the remover of that which +impeded it: The which again is directly opposite to what _Aristotle_ +saith, namely, that Figures are not the Causes of Motion. Besides, if +_Aristotle_ had admitted and not excluded Figures from being Causes of +not moving in some Bodies, which moulded into another Figure would +move, he would have impertinently propounded in a dubitative manner, +in the words immediately following, whence it is, that the large and +thinne Plates of Lead or Iron, rest upon the water, since the Cause +was apparent, namely, the Amplitude of Figure. Let us conclude, +therefore, that the meaning of _Aristotle_ in this place is to affirm, +that Figures are not the Causes of absolutely moving or not moving, +but only of moving swiftly or slowly: which we ought the rather to +believe, in regard it is indeed a most true conceipt and opinion. Now +the mind of _Aristotle_ being such, and appearing by consequence, +rather contrary at the first sight, then favourable to the assertion +of the Oponents, it is necessary, that their Interpretation be not +exactly the same with that, but such, as being in part understood by +some of them, and in part by others, was set down: and it may easily +be indeed so, being an Interpretation consonent to the sence of the +more famous Interpretors, which is, that the Adverbe _Simply_ or +_Absolutely_, put in the Text, ought not to be joyned to the Verbe to +_Move_, but with the Noun _Causes_: so that the purport of +_Aristotles_ words, is to affirm, That Figures are not the Causes +absolutely of moving or not moving, but yet are Causes _Secundum +quid_, _viz._ in some sort; by which means, they are called Auxiliary +and Concomitant Causes: and this Proposition is received and asserted +as true by _Signor Buonamico Lib. 5. Cap. 28._ where he thus writes. +_There are other Causes concomitant, by which some things float, and +others sink, among which the Figures of Bodies hath the first place_, +&c. + +Concerning this Proposition, I meet with many doubts and difficulties, +for which me thinks the words of _Aristotle_ are not capable of such a +construction and sence, and the difficulties are these. + +First in the order and disposure of the words of _Aristotle_, the +particle _Simpliciter_, or if you will _absolute_, is conjoyned with +the Verb _to move_, and seperated from the Noun _Causes_, the which is +a great presumption in my favour, seeing that the writing and the Text +saith, Figures are not the Cause of moving simply upwards or +downwards, but of quicker or slower Motion: and, saith not, Figures +are not simply the Causes of moving upwards or downwards, and when the +words of a Text receive, transposed, a sence different from that which +they sound, taken in the order wherein the Author disposeth them, it +is not convenient to inverte them. And who will affirm that +_Aristotle_ desiring to write a Proposition, would dispose the words +in such sort, that they should import a different, nay, a contrary +sence? contrary, I say, because understood as they are written; they +say, that Figures are not the Causes of Motion, but inverted, they +say, that Figures are the Causes of Motion, &c. + +Moreover, if the intent of _Aristotle_ had been to say, that Figures +are not simply the Causes of moving upwards or downwards, but only +Causes _Secundum quid_, he would not have adjoyned those words, _but +they are Causes of the more swift or slow Motion_; yea, the subjoining +this would have been not only superfluous but false, for that the +whole tenour of the Proposition would import thus much. Figures are +not the absolute Causes of moving upwards or downwards, but are the +absolute Cause of the swift or slow Motion; which is not true: because +the primary Causes of greater or lesser Velocity, are by _Aristotle_ +in the 4th of his _Physicks_, _Text. 71._ attributed to the greater or +lesser Gravity of Moveables, compared among themselves, and to the +greater or lesser Resistance of the _Medium's_, depending on their +greater or less Crassitude: and these are inserted by _Aristotle_ as +the primary Causes; and these two only are in that place nominated: +and Figure comes afterwards to be considered, _Text. 74._ rather as an +Instrumentall Cause of the force of the Gravity, the which divides +either with the Figure, or with the _Impetus_; and, indeed, Figure by +it self without the force of Gravity or Levity, would opperate +nothing. + +I adde, that if _Aristotle_ had an opinion that Figure had been in +some sort the Cause of moving or not moving, the inquisition which he +makes immediately in a doubtfull manner, whence it comes, that a Plate +of Lead flotes, would have been impertinent; for if but just before he +had said, that Figure was in a certain sort the Cause of moving or not +moving, he needed not to call in Question, by what Cause the Plate of +Lead swims, and then ascribing the Cause to its Figure; and framing a +discourse in this manner. Figure is a Cause _Secundum quid_ of not +sinking: but, now, if it be doubted, for what Cause a thin Plate of +Lead goes not to the bottom; it shall be answered, that that proceeds +from its Figure: a discourse which would be indecent in a Child, much +more in _Aristotle_; For where is the occasion of doubting? And who +sees not, that if _Aristotle_ had held, that Figure was in some sort a +Cause of Natation, he would without the least Hesitation have writ; +That Figure is in a certain sort the Cause of Natation, and therefore +the Plate of Lead in respect of its large and expatiated Figure swims; +but if we take the proposition of _Aristotle_ as I say, and as it is +written, and as indeed it is true, the ensuing words come in very +oppositely, as well in the introduction of swift and slow, as in the +question, which very pertinently offers it self, and would say thus +much. + +Figures are not the Cause of moving or not moving simply upwards or +downwards, but of moving more quickly or slowly: But if it be so, the +Cause is doubtfull, whence it proceeds, that a Plate of Lead or of +Iron broad and thin doth swim, &c. And the occasion of the doubt is +obvious, because it seems at the first glance, that the Figure is the +Cause of this Natation, since the same Lead, or a less quantity, but +in another Figure, goes to the bottom, and we have already affirmed, +that the Figure hath no share in this effect. + +Lastly, if the intent of _Aristotle_ in this place had been to say, +that Figures, although not absolutely, are at least in some measure +the Cause of moving or not moving: I would have it considered, that he +names no less the Motion upwards, than the other downwards: and +because in exemplifying it afterwards, he produceth no other +Experiments than of a Plate of Lead, and Board of Ebony, Matters that +of their own Nature go to the bottom, but by vertue (as our +Adversaries say) of their Figure, rest afloat; it is fit that they +should produce some other Experiment of those Matters, which by their +Nature swims, but retained by their Figure rest at the bottom. But +since this is impossible to be done, we conclude, that _Aristotle_ in +this place, hath not attributed any action to the Figure of simply +moving or not moving. + +But though he hath exquisitely Philosophiz'd, in investigating the +solution of the doubts he proposeth, yet will I not undertake to +maintain, rather various difficulties, that present themselves unto +me, give me occasion of suspecting that he hath not entirely displaid +unto us, the true Cause of the present Conclusion: which difficulties +I will propound one by one, ready to change opinion, whenever I am +shewed, that the Truth is different from what I say; to the confession +whereof I am much more inclinable than to contradiction. + + [Sidenote: _Aristotle_ erred in affirming a Needle dimitted long + wayes to sink.] + +_Aristotle_ having propounded the Question, whence it proceeds, that +broad Plates of Iron or Lead, float or swim; he addeth (as it were +strengthening the occasion of doubting) forasmuch as other things, +less, and less grave, be they round or long, as for instance a Needle +go to the bottom. Now I here doubt, or rather am certain that a Needle +put lightly upon the water, rests afloat, no less than the thin Plates +of Iron or Lead. I cannot believe, albeit it hath been told me, that +some to defend _Aristotle_ should say, that he intends a Needle +demitted not longwayes but endwayes, and with the Point downwards; +nevertheless, not to leave them so much as this, though very weak +refuge, and which in my judgement _Aristotle_ himself would refuse, I +say it ought to be understood, that the Needle must be demitted, +according to the Dimension named by _Aristotle_, which is the length: +because, if any other Dimension than that which is named, might or +ought to be taken, I would say, that even the Plates of Iron and Lead, +sink to the bottom, if they be put into the water edgewayes and not +flatwayes. But because _Aristotle_ saith, broad Figures go not to the +bottom, it is to be understood, being demitted broadwayes: and, +therefore, when he saith, long Figures as a Needle, albeit light, rest +not afloat, it ought to be understood of them when demitted longwayes. + + _Moreover, to say that_ Aristotle _is to be understood of the + Needle demitted with the Point downwards, is to father upon him a + great impertinency; for in this place he saith, that little + Particles of Lead or Iron, if they be round or long as a Needle, do + sink to the bottome; so that by his Opinion, a Particle or small + Grain of Iron cannot swim: and if he thus believed, what a great + folly would it be to subjoyn, that neither would a Needle demitted + endwayes swim? And what other is such a Needle, but many such like + Graines accumulated one upon another? It was too unworthy of such a + man to say, that one single Grain of Iron could not swim, and that + neither can it swim, though you put a hundred more upon it._ + +Lastly, either _Aristotle_ believed, that a Needle demitted longwayes +upon the water, would swim, or he believed that it would not swim: If +he believed it would not swim, he might well speak as indeed he did; +but if he believed and knew that it would float, why, together with +the dubious Problem of the Natation of broad Figures, though of +ponderous Matter, hath he not also introduced the Question; whence it +proceeds, that even long and slender Figures, howbeit of Iron or Lead +do swim? And the rather, for that the occasion of doubting seems +greater in long and narrow Figures, than in broad and thin, as from +_Aristotles_ not having doubted of it, is manifested. + +No lesser an inconvenience would they fasten upon _Aristotle_, who in +his defence should say, that he means a Needle pretty thick, and not a +small one; for take it for granted to be intended of a small one; and +it shall suffice to reply, that he believed that it would swim; and I +will again charge him with having avoided a more wonderfull and +intricate Probleme, and introduced the more facile and less +wonderfull. + +We say freely therefore, that _Aristotle_ did hold, that only the +broad Figure did swim, but the long and slender, such as a Needle, +not. The which nevertheless is false, as it is also false in round +Bodies: because, as from what hath been predemonstrated, may be +gathered, little Balls of Lead and Iron, do in like manner swim. + + [Sidenote: _Aristotle_ affirmeth some Bodies volatile for their + Minuity, Text. 42.] + +He proposeth likewise another Conclusion, which likewise seems +different from the truth, and it is, That some things, by reason of +their littleness fly in the Air, as the small dust of the Earth, and +the thin leaves of beaten Gold: but in my Opinion, Experience shews +us, that that happens not only in the Air, but also in the water, in +which do descend, even those Particles or Atomes of Earth, that +disturbe it, whose minuity is such, that they are not deservable, save +only when they are many hundreds together. Therefore, the dust of the +Earth, and beaten Gold, do not any way sustain themselves in the Air, +but descend downwards, and only fly to and again in the same, when +strong Windes raise them, or other agitations of the Air commove them: +and this also happens in the commotion of the water, which raiseth its +Sand from the bottom, and makes it muddy. But _Aristotle_ cannot mean +this impediment of the commotion, of which he makes no mention, nor +names other than the lightness of such Minutiae or Atomes, and the +Resistance of the Crassitudes of the Water and Air, by which we see, +that he speakes of a calme, and not disturbed and agitated Air: but in +that case, neither Gold nor Earth, be they never so small, are +sustained, but speedily descend. + + [Sidenote: _Democritus_ placed the Cause of Natation in certain + fiery Atomes.] + +He passeth next to confute _Democritus_[82], which, by his Testimony would +have it, that some Fiery Atomes, which continually ascend through the +water, do spring upwards, and sustain those grave Bodies, which are +very broad, and that the narrow descend to the bottom, for that but a +small quantity of those Atomes, encounter and resist them. + + [82] _Aristot. De Caelo_ lib. 4. cap. 6. text. 43. + +I say, _Aristotle_ confutes this position[83], saying, that that should +much more occurre in the Air, as the same _Democritus_ instances +against himself, but after he had moved the objection, he slightly +resolves it, with saying, that those Corpuscles which ascend in the +Air, make not their _Impetus_ conjunctly. Here I will not say, that +the reason alledged by _Democritus_ is true[84], but I will only say, it +seems in my judgement, that it is not wholly confuted by _Aristotle_, +whilst he saith, that were it true, that the calid ascending Atomes, +should sustain Bodies grave, but very broad, it would much more be +done in the Air, than in Water, for that haply in the Opinion of +_Aristotle_, the said calid Atomes ascend with much greater Force and +Velocity through the Air, than through the water. And if this be so, +as I verily believe it is, the Objection of _Aristotle_ in my +judgement seems to give occasion of suspecting, that he may possibly +be deceived in more than one particular: First, because those calid +Atomes, (whether they be Fiery Corpuscles, or whether they be +Exhalations, or in short, whatever other matter they be, that ascends +upwards through the Air) cannot be believed to mount faster through +Air, than through water: but rather on the contrary, they peradventure +move more impetuously through the water, than through the Air, as hath +been in part demonstrated above. And here I cannot finde the reason, +why _Aristotle_ seeing, that the descending Motion of the same +Moveable, is more swift in Air, than in water, hath not advertised us, +that from the contrary Motion, the contrary should necessarily follow; +to wit, that it is more swift in the water, than in the Air: for since +that the Moveable which descendeth, moves swifter through the Air, +than through the water, if we should suppose its Gravity gradually to +diminish, it would first become such, that descending swiftly through +the Air, it would descend but slowly through the water: and then +again, it might be such, that descending in the Air, it should ascend +in the water: and being made yet less grave, it shall ascend swiftly +through the water, and yet descend likewise through the Air: and in +short, before it can begin to ascend, though but slowly through the +Air, it shall ascend swiftly through the water: how then is it true, +that ascending Moveables move swifter through the Air, than through +the water? + + [83] _Democritus_ confuted by _Aristotle_, text 43. + + [84] _Aristotles_ confutation of _Democritus_ refuted by the + Author. + +That which hath made _Aristotle_ believe, the Motion of Ascent to be +swifter in Air, than in water, was first, the having referred the +Causes of slow and quick, as well in the Motion of Ascent, as of +Descent, only to the diversity of the Figures of the Moveable, and to +the more or less Resistance of the greater or lesser Crassitude, or +Rarity of the _Medium_; not regarding the comparison of the Excesses +of the Gravities of the Moveables, and of the _Mediums_: the which +notwithstanding, is the most principal point in this affair: for if +the augmentation and diminution of the Tardity or Velocity, should +have only respect to the Density or Rarity of the _Medium_, every Body +that descends in Air, would descend in water: because whatever +difference is found between the Crassitude of the water, and that of +the Air, may well be found between the Velocity of the same Moveable +in the Air, and some other Velocity: and this should be its proper +Velocity in the water, which is absolutely false. The other occasion +is, that he did believe, that like as there is a positive and +intrinsecall Quality, whereby Elementary Bodies have a propension of +moving towards the Centre of the Earth, so there is another likewise +intrinsecall[85], whereby some of those Bodies have an _Impetus_ of flying +the Centre, and moving upwards: by Vertue of which intrinsecall +Principle, called by him Levity, the Moveables which have that same +Motion more easily penetrate the more subtle _Medium_, than the more +dense: but such a Proposition appears likewise uncertain, as I have +above hinted in part, and as with Reasons and Experiments, I could +demonstrate, did not the present Argument importune me, or could I +dispatch it in few words. + + [85] Lib. 4. Cap. 5. + +The Objection therefore of _Aristotle_ against _Democritus_, whilst he +saith, that if the Fiery ascending Atomes should sustain Bodies grave, +but of a distended Figure, it would be more observable in the Air than +in the water, because such Corpuscles move swifter in that, than in +this, is not good; yea the contrary would evene, for that they ascend +more slowly through the Air: and, besides their moving slowly, they +ascend, not united together, as in the water, but discontinue, and, as +we say, scatter: And, therefore, as _Democritus_ well replyes, +resolving the instance they make not their push or _Impetus_ +conjunctly. + +_Aristotle_, in the second place, deceives himself, whilst he will +have the said grave Bodies to be more easily sustained by the said +Fiery ascending Atomes in the Air than in the Water: not observing, +that the said Bodies are much more grave in that, than in this, and +that such a Body weighs ten pounds in the Air, which will not in the +water weigh 1/2 an ounce; how can it then be more easily sustained in +the Air, than in the Water? + + [Sidenote: _Democritus_ confuted by the Authour.] + +Let us conclude, therefore, that _Democritus_ hath in this particular +better Philosophated than _Aristotle_. But yet will not I affirm, that +_Democritus_ hath reason'd rightly, but I rather say, that there is a +manifest Experiment that overthrows his Reason, and this it is, That +if it were true, that calid ascending Atomes should uphold a Body, +that if they did not hinder, would go to the bottom, it would follow, +that we may find a Matter very little superiour in Gravity to the +water, the which being reduced into a Ball, or other contracted +Figure, should go to the bottom, as encountring but few Fiery Atomes; +and which being distended afterwards into a dilated and thin Plate, +should come to be thrust upwards by the impulsion of a great Multitude +of those Corpuscles, and at last carried to the very Surface of the +water: which wee see not to happen; Experience shewing us, that a Body +_v. gra._ of a Sphericall Figure, which very hardly, and with very +great leasure goeth to the bottom, will rest there, and will also +descend thither, being reduced into whatsoever other distended Figure. +We must needs say then, either that in the water, there are no such +ascending Fiery Atoms, or if that such there be, that they are not +able to raise and lift up any Plate of a Matter, that without them +would go to the bottom: Of which two Positions, I esteem the second to +be true, understanding it of water, constituted in its naturall +Coldness. But if we take a Vessel of Glass, or Brass, or any other +hard matter, full of cold water, within which is put a Solid of a flat +or concave Figure, but that in Gravity exceeds the water so little, +that it goes slowly to the bottom; I say, that putting some burning +Coals under the said Vessel, as soon as the new Fiery Atomes shall +have penetrated the substance of the Vessel, they shall without doubt, +ascend through that of the water, and thrusting against the foresaid +Solid, they shall drive it to the Superficies, and there detain it, as +long as the incursions of the said Corpuscles shall last, which +ceasing after the removall of the Fire, the Solid being abandoned by +its supporters, shall return to the bottom. + +But _Democritus_ notes, that this Cause only takes place when we +treat of raising and sustaining of Plates of Matters, but very little +heavier than the water, or extreamly thin: but in Matters very grave, +and of some thickness, as Plates of Lead or other Mettal, that same +Effect wholly ceaseth: In Testimony of which, let's observe that such +Plates, being raised by the Fiery Atomes, ascend through all the depth +of the water, and stop at the Confines of the Air, still staying under +water: but the Plates of the Opponents stay not, but only when they +have their upper Superficies dry, nor is there any means to be used, +that when they are within the water, they may not sink to the bottom. +The cause, therefore, of the Supernatation of the things of which +_Democritus_ speaks is one, and that of the Supernatation of the +things of which we speak is another. But, returning to _Aristotle_[86], +methinks that he hath more weakly confuted _Democritus_, than +_Democritus_ himself hath done: For _Aristotle_ having propounded the +Objection which he maketh against him, and opposed him with saying, +that if the calid ascendent Corpuscles were those that raised the thin +Plate, much more then would such a Solid be raised and born upwards +through the Air, it sheweth that the desire in _Aristotle_ to detect +_Democritus_, was predominate over the exquisiteness of Solid +Philosophizing: which desire of his he hath discovered in other +occasions, and that we may not digress too far from this place, in the +Text precedent to this Chapter which we have in hand[87]; where he +attempts to confute the same _Democritus_ for that he, not contenting +himself with names only, had essayed more particularly to declare what +things Gravity and Levity were; that is, the Causes of descending and +ascending, (and had introduced Repletion and Vacuity) ascribing this +to Fire, by which it moves upwards, and that to the Earth, by which it +descends; afterwards attributing to the Air more of Fire, and to the +water more of Earth. But _Aristotle_ desiring a positive Cause, even +of ascending Motion, and not as _Plato_, or these others, a simple +negation, or privation, such as Vacuity would be in reference to +Repletion[88], argueth against _Democritus_ and saith: If it be true, as +you suppose, then there shall be a great Mass of water, which shall +have more of Fire, than a small Mass of Air, and a great Mass of Air, +which shall have more of Earth than a little Mass of water, whereby it +would ensue, that a great Mass of Air, should come more swiftly +downwards, than a little quantity of water: But that is never in any +case soever: Therefore _Democritus_ discourseth erroneously. + + [86] _Aristotle_ shews his desire of finding _Democritus_ in an + Error, to exceed that of discovering Truth. + + [87] Cap. 5. Text 41. + + [88] Id. ibid. + +But in my opinion, the Doctrine of _Democritus_ is not by this +allegation overthrown, but if I erre not, the manner of _Aristotle_ +deduction either concludes not, or if it do conclude any thing, it may +with equall force be restored against himself. _Democritus_ will grant +to _Aristotle_, that there may be a great Mass of Air taken, which +contains more Earth, than a small quantity of water, but yet will +deny, that such a Mass of Air, shall go faster downwards than a little +water, and that for many reasons. First, because if the greater +quantity of Earth, contained in the great Mass of Air, ought to cause +a greater Velocity than a less quantity of Earth, contained in a +little quantity of water, it would be necessary, first, that it were +true, that a greater Mass of pure Earth, should move more swiftly than +a less: But this is false, though _Aristotle_ in many places affirms +it to be true: because not the greater absolute, but the greater +specificall Gravity, is the cause of greater Velocity[89]: nor doth a Ball +of Wood, weighing ten pounds, descend more swiftly than one weighing +ten Ounces, and that is of the same Matter: but indeed a Bullet of +Lead of four Ounces, descendeth more swiftly than a Ball of Wood of +twenty Pounds: because the Lead is more _grave in specie_ than the +Wood. Therefore, its not necessary, that a great Mass of Air, by +reason of the much Earth contained in it, do descend more swiftly than +a little Mass of water[90], but on the contrary, any whatsoever Mass of +water, shall move more swiftly than any other of Air, by reason the +participation of the terrene parts _in specie_ is greater in the +water, than in the Air. Let us note, in the second place, how that in +multiplying the Mass of the Air, we not only multiply that which is +therein of terrene, but its Fire also: whence the Cause of ascending, +no less encreaseth, by vertue of the Fire, than that of descending on +the account of its multiplied Earth. It was requisite in increasing +the greatness of the Air, to multiply that which it hath of terrene +only, leaving its Fire in its first state, for then the terrene parts +of the augmented Air, overcoming the terrene parts of the small +quantity of water, it might with more probability have been pretended, +that the great quantity of Air, ought to descend with a greater +_Impetus_, than the little quantity of water. + + [89] The greater Specificall, not the greater absolute Gravity, + is the Cause of Velocity. + + [90] Any Mass of water shal move more swiftly, than any of Air, + and why. + +Therefore, the Fallacy lyes more in the Discourse of _Aristotle_, than +in that of _Democritus_, who with severall other Reasons might oppose +_Aristotle_, and alledge; If it be true, that the extreame Elements be +one simply grave, and the other simply light, and that the mean +Elements participate of the one, and of the other Nature; but the Air +more of Levity, and the water more of Gravity, then there shall be a +great Mass of Air, whose Gravity shall exceed the Gravity of a little +quantity of water, and therefore such a Mass of Air shall descend more +swiftly than that little water: But that is never seen to occurr: +Therefore its not true, that the mean Elements do participate of the +one, and the other quality. This argument is fallacious, no less than +the other against _Democritus_. + +Lastly, _Aristotle_ having said, that if the Position of _Democritus_ +were true, it would follow, that a great Mass of Air should move more +swiftly than a small Mass of water, and afterwards subjoyned, that +that is never seen in any Case: methinks others may become desirous to +know of him in what place this should evene, which he deduceth against +_Democritus_, and what Experiment teacheth us, that it never falls out +so. To suppose to see it in the Element of water, or in that of the +Air is vain, because neither doth water through water, nor Air through +Air move, nor would they ever by any whatever participation others +assign them, of Earth or of Fire: the Earth, in that it is not a Body +fluid, and yielding to the mobility of other Bodies, is a most +improper place and _Medium_ for such an Experiment: _Vacuum_, +according to the same _Aristotle_ himself, there is none, and were +there, nothing would move in it: there remains the Region of Fire, but +being so far distant from us, what Experiment can assure us, or hath +assertained _Aristotle_ in such sort, that he should as of a thing +most obvious to sence, affirm what he produceth in confutation of +_Democritus_, to wit, that a great Mass of Air, is moved no swifter +than a little one of water? But I will dwell no longer upon this +matter, whereon I have spoke sufficiently: but leaving _Democritus_, I +return to the Text of _Aristotle_, wherein he goes about to render the +true reason, how it comes to pass, that the thin Plates of Iron or +Lead do swim on the water; and, moreover, that Gold it self being +beaten into thin Leaves, not only swims in water, but flyeth too and +again in the Air. He supposeth that of Continualls[91], some are easily +divisible, others not: and that of the easily divisible, some are more +so, and some less: and these he affirms we should esteem the Causes. +He addes that that is easily divisible, which is well terminated, and +the more the more divisible, and that the Air is more so, than the +water, and the water than the Earth. And, lastly, supposeth that in +each kind, the lesse quantity is easlyer divided and broken than the +greater. + + [91] _De Caelo_ l. 4. c. 6. t. 44. + +Here I note, that the Conclusions of _Aristotle_ in generall are all +true, but methinks, that he applyeth them to particulars, in which +they have no place, as indeed they have in others, as for Example, Wax +is more easily divisible than Lead, and Lead than Silver, inasmuch as +Wax receives all the terms more easlier than Lead, and Lead than +Silver. Its true, moreover, that a little quantity of Silver is +easlier divided than a great Mass: and all these Propositions are +true, because true it is, that in Silver, Lead and Wax, there is +simply a Resistance against Division, and where there is the absolute, +there is also the respective. But if as well in water as in Air, there +be no Renitence against simple Division, how can we say, that the +water is easlier divided than the Air? We know not how to extricate +our selves from the Equivocation: whereupon I return to answer, that +Resistance of absolute Division is one thing, and Resistance of +Division made with such and such Velocity is another. But to produce +Rest, and to abate the Motion, the Resistance of absolute Division is +necessary; and the Resistance of speedy Division, causeth not Rest, +but slowness of Motion. But that as well in the Air, as in water, +there is no Resistance of simple Division, is manifest, for that there +is not found any Solid Body which divides not the Air, and also the +water: and that beaten Gold, or small dust, are not able to superate +the Resistance of the Air, is contrary to that which Experience shews +us, for we see Gold and Dust to go waving to and again in the Air, and +at last to descend downwards, and to do the same in the water, if it +be put therein, and separated from the Air. And, because, as I say, +neither the water, nor the Air do resist simple Division, it cannot be +said, that the water resists more than the Air. Nor let any object +unto me, the Example of most light Bodies, as a Feather, or a little +of the pith of Elder, or water-reed that divides the Air and not the +water, and from this infer, that the Air is easlier divisible than the +water; for I say unto them, that if they do well observe, they shall +see the same Body likewise divide the Continuity of the water[92], and +submerge in part, and in such a part, as that so much water in Mass +would weigh as much as the whole Solid. And if they shal yet persist +in their doubt, that such a Solid sinks not through inability to +divide the water, I will return them this reply, that if they put it +under water, and then let it go, they shall see it divide the water, +and presently ascend with no less celerity, than that with which it +divided the Air in descending: so that to say that this Solid ascends +in the Air, but that coming to the water, it ceaseth its Motion, and +therefore the water is more difficult to be divided, concludes +nothing: for I, on the contrary, will propose them a piece of Wood, or +of Wax, which riseth from the bottom of the water, and easily divides +its Resistance, which afterwards being arrived at the Air, stayeth +there, and hardly toucheth it; whence I may aswell say, that the water +is more easier divided than the Air. + + [92] _Archimed. De Insident. humi_ lib. 2. prop. 1. + +I will not on this occasion forbear to give warning of another fallacy +of these persons, who attribute the reason of sinking or swimming to +the greater or lesse Resistance of the Crassitude of the water against +Division, making use of the example of an Egg, which in sweet water +goeth to the bottom, but in salt water swims; and alledging for the +cause thereof, the faint Resistance of fresh water against Division, +and the strong Resistance of salt water. But if I mistake not, from +the same Experiment, we may aswell deduce the quite contrary; namely, +that the fresh water is more dense, and the salt more tenuous and +subtle, since an Egg from the bottom of salt water speedily ascends to +the top, and divides its Resistance, which it cannot do in the fresh, +in whose bottom it stays, being unable to rise upwards. Into such like +perplexities, do false Principles Lead men: but he that rightly +Philosophating, shall acknowledge the excesses of the Gravities of the +Moveables and of the Mediums, to be the Causes of those effects, will +say, that the Egg sinks to the bottom in fresh water, for that it is +more grave than it, and swimeth in the salt, for that its less grave +than it: and shall without any absurdity, very solidly establish his +Conclusions. + +Therefore the reason totally ceaseth, that _Aristotle_ subjoyns in the +Text saying[93]; The things, therefore, which have great breadth remain +above, because they comprehend much, and that which is greater, is not +easily divided. Such discoursing ceaseth, I say, because its not true, +that there is in water or in Air any Resistance of Division; besides +that the Plate of Lead when it stays, hath already divided and +penetrated the Crassitude of the water, and profounded it self ten or +twelve times more than its own thickness: besides that such Resistance +of Division, were it supposed to be in the water, could not rationally +be affirmed to be more in its superiour parts than in the middle, and +lower: but if there were any difference, the inferiour should be the +more dense, so that the Plate would be no less unable to penetrate the +lower, than the superiour parts of the water; nevertheless we see that +no sooner do we wet the superiour Superficies of the Board or thin +Piece of Wood, but it precipitatly, and without any retension, +descends to the bottom. + + [93] Text 45. + +I believe not after all this, that any (thinking perhaps thereby to +defend _Aristotle_) will say, that it being true, that the much water +resists more than the little, the said Board being put lower +descendeth, because there remaineth a less Mass of water to be divided +by it: because if after the having seen the same Board swim in four +Inches of water, and also after that in the same to sink, he shall try +the same Experiment upon a profundity of ten or twenty fathom water, +he shall see the very self same effect. And here I will take occasion +to remember, for the removall of an Error that is too common; That +that Ship or other whatsoever Body, that on the depth of an hundred or +a thousand fathom, swims with submerging only six fathom of its own +height, [_or in the Sea dialect, that draws six fathom water_] shall +swim in the same manner in water, that hath but six fathom and half an +Inch of depth[94]. Nor do I on the other side, think that it can be said, +that the superiour parts of the water are the more dense, although a +most grave Authour hath esteemed the superiour water in the Sea to be +so, grounding his opinion upon its being more salt, than that at the +bottom: but I doubt the Experiment, whether hitherto in taking the +water from the bottom, the Observatour did not light upon some spring +of fresh water there spouting up: but we plainly see on the contrary, +the fresh Waters of Rivers to dilate themselves for some miles beyond +their place of meeting with the salt water of the Sea, without +descending in it, or mixing with it, unless by the intervention of +some commotion or turbulency of the Windes. + + [94] A Ship that in 100 Fathome water draweth 6 Fathome, shall + float in 6 Fathome and 1/2 an Inch of depth. + +But returning to _Aristotle_, I say, that the breadth of Figure hath +nothing to do in this business more or less, because the said Plate of +Lead, or other Matter, cut into long Slices, swim neither more nor +less[95]; and the same shall the Slices do, being cut anew into little +pieces, because its not the breadth but the thickness that operates in +this business. I say farther, that in case it were really true, that +the Renitence to Division were the proper Cause of swimming[96], the +Figures more narrow and short, would much better swim than the more +spacious and broad, so that augmenting the breadth of the Figure, the +facility of supernatation will be deminished, and decreasing, that +this will encrease. + + [95] Thickness not breadth of Figure to be respected in Natation. + + [96] Were Renitence the cause of Natation, breadth of Figure would + hinder the swiming of Bodies. + +And for declaration of what I say, consider that when a thin Plate of +Lead descends, dividing the water, the Division and discontinuation is +made between the parts of the water, invironing the perimeter or +Circumference of the said Plate, and according to the bigness greater +or lesser of that circuit, it hath to divide a greater or lesser +quantity of water, so that if the circuit, suppose of a Board, be ten +Feet in sinking it flatways, it is to make the seperation and +division, and to so speak, an incission upon ten Feet of water; and +likewise a lesser Board that is four Feet in Perimeter, must make an +incession of four Feet. This granted, he that hath any knowledge in +Geometry, will comprehend, not only that a Board sawed in many long +thin pieces, will much better float than when it was entire, but that +all Figures, the more short and narrow they be, shall so much the +better swim. Let the Board A B C D be, for Example, eight Palmes long, +and five broad, its circuit shall be twenty six Palmes; and so many +must the incession be, which it shall make in the water to descend +therein: but if we do saw ir, as suppose into eight little pieces, +according to the Lines E F, G H, {&}c. making seven Segments, we must +adde to the twenty six Palmes of the circuit of the whole Board, +seventy others; whereupon the eight little pieces so cut and +seperated, have to cut ninty six Palmes of water. And, if moreover, we +cut each of the said pieces into five parts, reducing them into +Squares, to the circuit of ninty six Palmes, with four cuts of eight +Palmes apiece; we shall adde also sixty four Palmes, whereupon the +said Squares to descend in the water, must divide one hundred and +sixty Palmes of water, but the Resistance is much greater than that of +twenty six; therefore to the lesser Superficies, we shall reduce them, +so much the more easily will they float: and the same will happen in +all other Figures, whose Superficies are simular amongst themselves, +but different in bigness: because the said Superficies, being either +deminished or encreased, always diminish or encrease their Perimeters +in subduple proportion; to wit, the Resistance that they find in +penetrating the water; therefore the little pieces gradually swim, +with more and more facility as their breadth is lessened. + +[Illustration] + + _This is manifest; for keeping still the same height of the Solid, + with the same proportion as the Base encreaseth or deminisheth, + doth the said Solid also encrease or diminish; whereupon the Solid + more diminishing than the Circuit, the Cause of Submersion more + diminisheth than the Cause of Natation: And on the contrary, the + Solid more encreasing than the Circuit, the Cause of Submersion + encreaseth more, that of Natation less._ + +And this may all be deduced out of the Doctrine of _Aristotle_ against +his own Doctrine. + +Lastly, to that which we read in the latter part of the Text[97], that is +to say, that we must compare the Gravity of the Moveable with the +Resistance of the Medium against Division, because if the force of the +Gravity exceed the Resistance of the _Medium_, the Moveable will +descend, if not it will float. I need not make any other answer, but +that which hath been already delivered; namely, that its not the +Resistance of absolute Division, (which neither is in Water nor Air) +but the Gravity of the _Medium_ that must be compared with the Gravity +of the Moveables; and if that of the _Medium_ be greater, the Moveable +shall not descend, nor so much as make a totall Submersion, but a +partiall only; because in the place which it would occupy in the +water, there must not remain a Body that weighs less than a like +quantity of water: but if the Moveable be more grave, it shall descend +to the bottom, and possess a place where it is more conformable for it +to remain, than another Body that is less grave. And this is the only +true proper and absolute Cause of Natation and Submersion, so that +nothing else hath part therein: and the Board of the Adversaries +swimmeth, when it is conjoyned with as much Air, as, together with it, +doth form a Body less grave than so much water as would fill the place +that the said Compound occupyes in the water; but when they shall +demit the simple Ebony into the water, according to the Tenour of our +Question, it shall alwayes go to the bottom, though it were as thin as +a Paper. + + [97] Lib. 4. c. 6. Text 45. + +[Decoration] + +FINIS. + +[Decoration] + + * * * * * + + [Detailed Transcriber's Notes + + The text has been made to match the original text as much as + possible including variation in spelling, punctuation, italics etc. + The following, details apparent printer's errors as well as changes + or additions to aid readability of text. + + Page 1, missing full stop after abbreviation gr. '0 gr 54 min.'. + + Page 3, sidenote, missing space between words 'the Authority ofan + Author.'. + + Page 3, printer's error, augmentarion for augmentation 'and + augmentarion of Masse'. + + Page 4, missing letter t 'tha{t} that proceeded not'. + + Page 4, printer's error or inconsistent punctuation, 'my paynes and + time. and although'. + + Page 6, inconsistent punctuation, full stop after axiome where as + there are none after those following 'AXIOME. I.'. + + Page 9, missing full stop added to end of paragraph 'or else an + upright Prisme.'. + + Page 11, printer's error, missing letter C in illustration, 'the + Prisme A C D B to be placed'. + + Page 15, printer's error or archaic lettering, final y looking like + a 7 in original text'and of the Specifick Gravit{y}'. + + Page 16, printer's error, letter N for T in text to refer to + illustration, 'if the Vessell E N S F'. + + Page 16, printer's error, duplicate word in text 'equalizeth the + Force and and Moment,'. + + Page 17, printer's error, rhe for the 'as in rhe Stilliard,'. + + Page 17, missing space between words 'asoften as that'. + + Page 18, sidenote, printer's error, specifiaclly for specifically + 'A Solid specifiaclly graver'. + + Page 20, potential printer's error, properly for property, 'but + this properly they have'. + + Page 20, printer's error, n for u 'loseth all a{u}thenticalness'. + + Page 22, printer's error or variation in spelling, Benonamico for + Buonamico 'it seemes that Benonamico'. + + Page 23, printer's error, missing i 'accordng to its excess'. + + Page 24, missing line at the end of page in original text 'its + Region it loseth all'. + + Page 26, missing letter n 'u{n}able by its small weight'. + + Page 29, missing letter e 'that I have gon{e} about'. + + Page 32, unclear symbol in original text 'other Figure, {&}c.'. + + Page 37, potential printer's error, comma in unusual position + 'whatever Figure, goeth always'. + + Page 38, missing space between words 'Superficies might bedry:'. + + Page 39, missing letter t, unied for united 'which holds them unied'. + + Page 41, printer's error, Motitions for Motions 'all Motitions are + made'. + + Page 42, sidenote, possible missing letter e, 'Se{e} what satisfaction'. + + Page 43, printer's error, Subdidivisions for Subdivisions, 'other + Subdidivisions,'. + + Page 49, missing letter i, dminishing for diminishing 'or dminishing + it by dividing'. + + Page 50, sidenote, printer's error, missing letter l, hep for help + 'float by hep of'. + + Page 53, printer's error, missing letter n, beig for being 'beig + double in Gravity'. + + Page 54, printer's error, missing letter l, 'sha{l}l also descend.'. + + Page 55, printer's error, missing letter r, 'to fo{r}m Solid Bodies'. + + Page 56, printer's error, missing letter A, 'Cone S {A} T'. + + Page 57, printer's error, missing letter t, 'of which i{t} may + descend'. + + Page 58, sidenote, printer's error, inverted n, 'Natatio{n} easiest + effected'. + + Page 59, missing letter u, 'witho{u}t all Question,'. + + Page 59, printer's error, inverted n, 'with an other Experime{n}t'. + + Page 59, potential printer's error, sidenote ends with comma, 'Or + rather Contiguity,'. + + Page 61, missing letter a, 'that in this c{a}se the water,'. + + Page 74, printer's error, ir for it, 'but if we do saw ir,'. + + Page 75, unclear symbol in original text '{&}c. making seven + Segments'. + ] + + + + + +End of Project Gutenberg's Discourse on Floating Bodies, by Galileo Galilei + +*** END OF THIS PROJECT GUTENBERG EBOOK DISCOURSE ON FLOATING BODIES *** + +***** This file should be named 37729.txt or 37729.zip ***** +This and all associated files of various formats will be found in: + https://www.gutenberg.org/3/7/7/2/37729/ + +Produced by Tim Madden and the Online Distributed +Proofreading Team at https://www.pgdp.net (This file was +produced from images generously made available by The +Internet Archive) + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. 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