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The words were these: that the antagonists having an opinion that shape would alter the behavior of solid bodies in sinking or not sinking, rising or not rising, in the same medium, as for example in the same water, in such a way that, for example, a solid in spherical shape should sink to the bottom, but being molded into some other shape should not sink, and I, holding the contrary opinion, affirm that a solid body which sinks when it has spherical shape shall do the same in any other shape, etc.
But to be in the water implies to be placed in the water, and by Aristotle's own definition of place, "to be placed" means to be surrounded by the surfaces of the ambient body. Therefore, then, the two shapes will be in the water when the surfaces of the water shall enclose and surround them. But when the adversaries show the ebony chip not sinking, they put it not into the water but upon the water, where, being held up by a certain impediment (as by and by we will show), it is surrounded partly by water and partly by air, which is contrary to our agreement, which was that the bodies should be in water, and not partly in water and partly in air.
This is also clear from the question's being phrased equally about things which go to the bottom as about things which rise from the bottom to float, and who does not see that things placed on the bottom must be surrounded by water?
It is now to be noted that the ebony chip and the ball, put into the water, both sink, but the ball more swiftly and the chip more slowly, and slower and slower according as it is more broad and thin. And the breadth of shape is the true cause of this slowness. But these broad chips that slowly sink are the same ones that float, being put lightly on the water surface. Therefore, if it were true what my adversaries say, the same shape in the same water would cause rest in one case and slowness of motion in the other, which is impossible. For every particular shape which sinks to the bottom has of necessity its own determinate slowness, proper and natural to it, so that every other slowness, whether greater or lesser, is improper to its nature. If therefore, a board of, say, a foot square, descends naturally with a fixed slowness 8, it is impossible that it should descend with 10 or 20 unless some new impediment should hold it back. Much less can it come to rest by reason of the same shape, and completely cease to move. Rather it is necessary that whenever it comes to rest there should be some impediment greater than the breadth of its shape. Therefore it must be something else, other than the shape, that stops the ebony board at the water surface, since the only effect of shape is retardation of the motion, so that it descends more slowly than the ball. Let it be confessed, therefore, arguing rationally, that the true and only cause of the ebony's going to the bottom is the excess of its specific weight over the specific weight of water, and the cause of the greater or lesser slowness is the breadth of the shape or the contractedness of the shape. But it cannot by any means be allowed that the shape is the cause of its resting on the surface. For one thing, since a broader shape produces greater slowness, there cannot be any breadth, no matter how immense, which does not have a corresponding slowness, different from rest. And for another thing, the shapes produced by my antagonists as causing rest are the very same shapes which also go to the bottom.
I will not omit another reason, founded also upon experience, and quite conclusive, if I do not deceive myself, to show that the breadth of shape and the resistance of water against penetration have nothing to do with rising, sinking, or resting in the water. Take a piece of wood or other substance, of which a ball ascends from the bottom of the water to the surface more slowly than a ball of ebony of the same size divides the water in sinking; as for example, let the wood be walnut. Then take a chip of walnut similar and equal to the ebony chip of my antagonists (which floats); and if were true that it floats above water by reason of its shape, unable because of its breadth to pierce the materiality of the water, the other chip of walnut, without any question, being thrust to the bottom, will stay there, as less able, through the same impediment of its shape, to divide the said resistance of the water. But if we shall find, and by experience see, that not only a thin chip, but every other shape of the same walnut will return to float, as undoubtedly we shall, then I must desire my opponents to forbear attributing the floating of the ebony to its shape, since the resistance of the water is the same in ascending as in sinking, and the force of the walnut to rise is less than the force of the ebony to sink.
Nay, I will say more, that if we shall consider gold in comparison with water, we shall find that it exceeds it in specific weight almost twenty times, so that the force and impetus with which a ball of gold goes to the bottom is very great. In contrast, there are substances like virgin wax and some woods which are no more than a fiftieth part less in specific weight than water, so that their ascent is very slow, a thousand times weaker in impetus than that of gold in sinking. Yet in spite of this, a plate of gold floats without sinking to the bottom, and on the contrary we cannot make a cake of wax or thin wooden chip which will rest on the bottom without ascending. Now if shape can obstruct the penetration and impede the descent of gold, with its great impetus, how can it not be enough to resist the same penetration of the other substance in ascending, when it has scarcely a thousandth part of the impetus that the gold has in sinking? It is necessary, therefore, that what suspends the thin plate of gold or the ebony chip upon the water be something that is lacking to the other cakes and chips of material less heavy than water. For they, being put on the bottom, rise up to the surface without any obstruction, although they are certainly flat enough and broad enough in shape. Therefore it is not breadth of shape which makes the gold and ebony float.
What, then, shall we say that it is? I, for myself, will say that it must be the opposite of that which is the cause of sinking: for going to the bottom and staying at the top are contrary effects, and of contrary effects there must be contrary reasons. And because the excess of their specific weight above the specific weight of water is, without doubt, the cause of the sinking of the ebony chip and the flat 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 perhaps not hitherto observed, comes to join itself to the said chip, making it not heavier than water, as it was when it sank, but lighter. But such new levity cannot depend on the shape, because shapes do not add to or subtract from weight, and because the chip makes no alteration of its shape when it goes to the bottom from what it was when it floated. Ma tal nuova leggerezza non può depender dalla figura, sì perché le figure non aggiungono o tolgono il peso, sì perché nella tavoletta non si fa mutazione alcuna di figura, quand'ella va al fondo, da quello ch'ell'aveva mentre galleggiava.
 Now let us return to take the thin plate of gold, or silver, or the thin ebony chip, and let us lay it lightly upon the water, so that it stays there without sinking, and diligently observe the effect. And first, see how false is the assertion of Aristotle and our opponents, namely that it stays above the water through its inability to pierce and penetrate the resistance of the water's materiality. For it will manifestly appear not only that the said plates have penetrated the water, but also that they are a considerable distance lower than the surface, which keeps its height and forms as it were a rampart on all sides, round about the said plates, at the bottom of which they float; And according as the said plates shall be heavier in specific weight than water, two, four, ten, or twenty times, it is necessary that their surfaces should stay below the surface of the water by that factor times the thickness of those plates, as we shall show more distinctly below. In the meantime, for the easier understanding of what I say, observe with me the accompanying figure, in which let us suppose the surface of the water to be spread out according to the lines FLDB, upon which, if one puts a chip of material heavier in specific weight than water, but so lightly that it does not sink, it will not float above, but rather will enter with its whole thickness into the water; and moreover it will even sink, as we see by the chip AI,OI, whose breadth is entirely sunk into the water, the little ramparts of water LA and DO surrounding it, whose surface is notably higher than the surface of the chip. See now whether it is true that the shape's inability to penetrate the materiality of the water is the reason that it does not go to the bottom.
But if it has already penetrated and overcome the continuity of the water, and is of its own nature heavier than the water, why does it not proceed in its sinking, instead of stopping and suspending itself within that little dimple or cavity which it has made with its weight in the water? I answer, because in submerging itself so far that its surface becomes level with that of the water it loses a part of its weight, and loses the rest of it as it submerges and descends beneath the surface of the water, which makes ramparts and banks round about it, and it sustains this loss by means of its drawing after it, and carrying along with it, the air that is above it, adhering to it by contact. This air fills the cavity surrounded by the ramparts of water, so that what is placed in the water and sinks is not just the ebony chip or plate of iron, but a composition of ebony and air, from which results a solid no longer heavier than water, as was the simple ebony, or the simple gold. And if we consider exactly what the solid is that, in this experiment, enters into the water, and which is compared to the water's weight, it will be found to be the entire region beneath the water's surface, which is an aggregate and compound of an ebony chip and an almost equal amount of air, or a volume 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 that the substance be the same, and only the shape be changed. Therefore you must remove that air which, being conjoined with the chip, makes it become another body less heavy than water, and put only the ebony into the water, and you shall certainly see the chip descend to the bottom; and if that does not happen, you have won the day. And to separate the air from the ebony, you need only to wet the surface of the said chip with water, for if water is thus interposed between the board and the air, the other surrounding water will run together without any impediment, and will receive into itself the bare ebony alone, as it was supposed to do.
But I think I hear some of my adversaries cunningly opposing this, and telling me that they will not allow on any account that their chip be wetted, because the weight added to it by the water, 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 substance be the same.
To this I answer, first, that if we are talking about the effect of shape on bodies in water, no one can suppose them to be put into the water without being wet; nor do I desire more to be done to the chip than I allow you to do with the ball. Moreover, it is untrue that the chip sinks by virtue of the new weight added to it by the water in just the slight wetting of it: for I will put ten or twenty drops of water upon the same chip while it is sustained upon the water, and these drops, because they are not conjoined with the other surrounding water, shall not so increase the weight of it as to make it sink. But if the chip is taken out, and all the water wiped off that was added to it, and I should then bathe all its surface with just one very small drop, and put it again upon the water, it will sink without doubt, the other water running over it to cover it, not being kept back by the air above it, since the air is no longer in contact with the ebony, due to the interposition of the thin layer of water, and it does not in the least oppose the closing of the water over it. But rather, to speak better, it descends freely, because it is surrounded and covered with water as soon as its upper surface, prepared with a thin layer of water, arrives at the level of the water surface. To say, in the next place, that water can increase the weight of things that are placed into it is most false, for water has no weight in water, since it doesn't sink. Indeed, if we would consider well what any immense volume of water does to a heavy body that is placed in it, we shall find experimentally that on the contrary, it will rather in large part diminish the weight of it, and that we may be able to lift a huge stone from the bottom of the water which we could not budge if the water were removed. And let them not tell me by way of reply that although the added water does not increase the weight of things in water, yet it increases the weight of things that are floating, and are partly in the water and partly in the air, as is seen, for example, in a brass kettle, which as long as it is empty of water and filled only with air shall float, but pouring water into it you will make it so heavy that it shall sink to the bottom by reason of the new weight added to it. To this I will answer, as above, that the weight of the water contained in the vessel is not what sinks it to the bottom, but the specific weight of the brass, which is greater than the specific weight of water. For if the vessel were less heavy than water, the Ocean would not be enough to submerge it. And give me leave to repeat it once again, as the fundamental and principal point in this case, that the air contained in this vessel before the infusion of water was what kept it afloat, since there was thus formed a composition of brass and air less heavy than an equal volume of water. And the volume the vessel occupies in the water while it is floating is not equal to the volume of the brass alone, but of the brass and the air together, meaning the air which fills that part of the vessel that is below the level of the water. Moreover, when the water is poured in, the air is removed, and there is made a composition of brass and water, heavier in specific weight than water, but not by virtue of the water poured in, as having greater specific weight than the other water, but by the specific weight of the brass, and because the air has been removed. Now just as someone would speak falsely if he would say that brass, that by its nature goes to the bottom, acquires the virtue of lying in water without sinking if it is made into the shape of a kettle, -- because brass made into any shape whatever always sinks, provided that what is put into the water is simply brass, and it is not the shape of the vessel that makes the brass float, but because it is not purely brass which is put into the water, but an aggregate of brass and air -- just so it is neither more nor less false that a thin plate of brass or of ebony floats by virtue of its dilated and broad shape. For the truth is that it holds up without sinking because what 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 (since I have many a time seen vessels of metal and thin pieces of various heavy substances float, by virtue of the air conjoined with them) to my conclusion that shape is not the cause of floating or sinking of such solids as are placed in the water. Nay more, I cannot omit, but must tell my antagonists that this new conceit of denying that the upper surface of the chip should be wet may suggest to onlookers a poverty of arguments of defense on their part, since they said nothing about wetting in the beginning of our dispute, nor questioned it at all. Indeed, the original argument was about the floating of flakes of ice, and it would be too foolish to require that their surfaces be dry, besides which these pieces of ice always float, whether they are wet or dry, and because of their shape as my adversaries say.
Some perhaps, by way of defense, may say that wetting the upper surface of the ebony chip, even though it is unable to pierce and penetrate the water, may bear it downwards, if not by the weight of the additional water, then by that desire and inclination that the parts of the water above have to re-unite and rejoin themselves, and by the motion of these parts the said chip comes somehow to be pressed downwards.
This weak refuge will be removed if we simply consider that the wish of the water below not to be divided is as great as the wish of the upper parts to come together; nor can the upper parts unite themselves without disuniting the lower parts of the water. Therefore it follows, by necessary consequence, that this is not the reason it sinks. Moreover, the same that is said of the upper parts of the water may with equal reason be said of the lower, namely that since they desire to unite, they shall force the said chip upwards.
Perhaps some of these gentlemen who disagree with me will be surprised that I affirm that the contiguous air above the plate of brass or silver is able to sustain it above the water, as if I would attribute to air, in a certain sense, a kind of magnetic virtue of sustaining heavy bodies to which it is contiguous. To satisfy everyone, on all such doubts, I have been considering how I might demonstrate by some other sensible experiment how true it is that the contiguous air sustains those solids, which although by nature apt to descend to the bottom, do not sink if they are placed gently onto the water, unless they are first thoroughly wetted. And I have found that if one of these bodies has descended to the bottom, one can convey to it (without touching it in the least) a little air, which joins with the top of the body and becomes 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 remains in the same manner until such time as the assistance of the conjoined air is taken away. . And to this effect I have taken a ball of wax, and made it so heavy with a little lead that it descends in leisurely fashion to the bottom, making all its surfaces very smooth and polished. And this, being put gently into the water, almost wholly submerges, there remaining visible only a little of the very top, which holds the ball up as long as it is conjoined with the air, but if the contiguity of the air is taken away by wetting it, it sinks to the bottom and remains there. Now to make it return to the top by virtue of the air which sustained it before, thrust into the water a glass upside-down, with the mouth downwards, which carries with it the air which it contains, and move this towards the ball, lowering it until you see through the transparent glass that the contained air has reached the top of the ball. Then gently withdraw the glass upwards, and you shall see the ball rise, and afterwards stay on the top of the water, if you carefully take the glass out of the water without disturbing it too much and causing it to move. There is, therefore, a certain affinity between the air and other bodies which holds them together, so that they do not separate without a kind of violence. The same likewise is seen in the water, for if we completely submerge some body in it, so that it is thoroughly wetted, in drawing it gently out again we shall see the water follow it, and rise notably above its surface before it separates from it. Solid bodies also, if they are smooth and have identical surfaces, so that they make an exact contact, without the interposition of the least air between them, which might yield until the ambient medium rushes in to fill the space, hold very firmly together, and are not to be separated without great force. But because air, water, and other liquids shape themselves very exactly to contact with any solid bodies, so that their surfaces exquisitely adapt themselves to that of the solids, without anything 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 surfaces only very rarely meet with exactness of contact. This is therefore that magnetic virtue, which holds firmly connected all bodies which touch without interposition of flexible fluids. And who knows but that such a contact, when it is very exact, may be a sufficient cause of the union and continuity of the parts of a natural body?
Now, pursuing my purpose, I say that we need not trouble ourselves about the tenacity that the parts of the water have among themselves to resist division, penetration, and separation, because there is no such coherence or resistance to division. For if there were, it would be no less in the internal parts than in those nearer the upper or external surface, and the same chip, finding always the same resistance, would stop in the middle of the water no less than it does at the surface, which is false. Moreover, what resistance can we attribute to the continuity of the water if we see that it is impossible to find any body of whatsoever substance, shape, or size, which, being put into the water, is obstructed and impeded by the tenacity of the parts of the water for one another, but rather that all are moved either upwards or downwards according as the cause of their motion transports them? And what greater proof of this can we desire than that which we daily see in muddy waters, which being put into vessels to be drunk, and being after some hours of settling still cloudy, yet in the end after four or six days they are wholly settled, and become pure and clear? This resistance to penetration cannot hold back those impalpable and insensible particles which, by reason of their exceedingly small force, spend six days in descending the space of a yard?
Nor let them say that seeing such bodies consume six days in descending such a little way is itself a sufficient argument of the water's resistance of division; because that is not resisting division, but retarding motion; and it would be foolish to say that a thing opposes division and in the same instant it permits itself to be divided. Nor does retardation of motion favour my adversaries' cause at all, for what they require is something that completely inhibits motion and produces rest. It is necessary, therefore, to find bodies that stop in water, if one wants to show its repugnance to division, and not bodies that move in water, however slowly.
What then is this materiality of water, with which it resists division? What, I beseech you, should it be, if we find it impossible to bring a substance to have so nearly equal a specific weight with water that it remains suspended between the two waters, although we have (as we have said above) with all diligence attempted it, forming it into a broad plate and so nearly in equilibrium that as much lead as the fourth part of a grain of mustard seed added to the same expanded plate that in air (i.e. out of the water) would weigh four or six pounds, sinks it to the bottom, and being subtracted it ascends to the surface of the water? I cannot see (if what I say is true, and it is most true) what minute virtue and force we can possibly find or imagine which is less than the resistance of the water against division and penetration; whereupon we must of necessity conclude that it is zero. Because if it were of any sensible power, some large plate might be found or compounded of a substance equal in specific weight to water, which not only stays between two waters, but moreover would not be able to descend or ascend without noticeable force. . We may draw the same conclusion from another experiment, showing that water gives way also in the same manner to division sideways. For if we should place any great mass that floats in settled, standing water, then pulling it with a single woman's hair, we may carry it from place to place without any opposition, no matter what shape it has, even if it displaces a large amount of water, as for instance a great beam would do moved sideways.
Perhaps some might oppose me and say that if the resistance against division were nothing, as I say, then ships would not need the force of oars and sails to move them from place to place in a tranquil sea or standing lake. To him that should make such an objection, I would reply that water does not oppose or resist division simply, but sudden division, and with so much greater resistance the greater the velocity is. And the cause of this resistance does not depend on its materiality, or any other thing that absolutely opposes division, but because when the parts of the water are divided, in giving way to the solid that is moved in it, they must also move locally, some to one side and some to the other, and some downwards. And this must be done no less by the waves which run before the ship than the ones which follow, because when the ship proceeds forward, to make room for itself it must push away with its prow the adjacent parts of the water, as much on one side as on the other, and move them sideways by half the breadth of the hull. And those waves must travel the same distance behind the stern which come together again in the middle, filling the space which the ship in advancing forward leaves empty. Now because all motions are made in time, 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 through a certain space, shall not be moved the same space in a shorter time, unless by a greater power; therefore the broader ships move slower than the narrower, if they are driven by an equal force: and the same vessel requires greater force of wind or oars in proportion as it is to move the faster.
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