Galilei, Galileo, Discourse concerning the natation of bodies, 1663

Table of figures

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              peradventure not hitherto obſerved, cometh to meet with the ſaid
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              Board, rendering it no longer as it was before, whilſt it did fink more
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              ponderous than the water, but leſs.</s>
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              <s>Now, let us return to take the thin Plate of Gold, or of Silver, or the
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              thin Board of Ebony, and let us lay it lightly upon the water, ſo that it
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              ſtay there without ſinking, and diligently obſerve its effect. </s>
              <s>And
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              firſt, ſee how falſe the aſſertion of
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              Aristotle,
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              and our oponents is, to wit,
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              that it ſtayeth above water, through its unability to pierce and
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              trate the Reſiſtance of the waters Craſſitude: for it will manifeſtly
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              appear, not only that the ſaid Plates have penetrated the water, but
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              alſo that they are a conſiderable matter lower than the Surface of the
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              ſame, the which continueth eminent, and maketh as it were a Rampert
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              on all ſides, round about the ſaid Plates, the profundity of which they
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              ſtay ſwimming: and, according as the ſaid Plates ſhall be more grave
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              than the water, two, four, ten or twenty times, it is neceſſary, that
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              their Superficies do ſtay below the univerſall Surface of the water, ſo
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              much more, than the thickneſs of thoſe Plates, as we ſhal more diſtinctly
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              ſhew anon. </s>
              <s>In the mean ſpace, for the more eaſie underſtanding of what
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              I ſay, obſerve with me a little the preſent
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              Scheme: in which let us ſuppoſe the Surface
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              of the water to be diſtended, according to the
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              Lines F L D B, upon which if one ſhall put a
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              board of matter ſpecifically more grave than
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              water, but ſo lightly that it ſubmetge not, it
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              ſhall not reſt any thing above, but ſhall enter with its whole thickneſs
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              into the water: and, moreover, ſhall ſink alſo, as we ſee by the Board
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              A I, O I, whoſe breadth is wholly ſunk into the water, the little
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              perts of water L A and D O incompaſſing it, whoſe Superficies is
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              tably higher than the Superficies of the Board. </s>
              <s>See now whether it be
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              true, that the ſaid Board goes not to the Bottom, as being of Figure
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              unapt to penetrate the Craſſitude of the water.</s>
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              <s>But, if it hath already penetrated, and overcome the Continuity of
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              the water, & is of its own nature more grave than the ſaid water, why
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              doth it not proceed in its ſinking, but ſtop and ſuſpend its ſelf within
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              that little dimple or cavitie, which with its ponderoſity it hath made in
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              the water? </s>
              <s>I anſwer; becauſe that in ſubmerging it ſelf, ſo far as till its
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              Superficies come to the Levell with that of the water, it loſeth a part
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              of its Gravity, and loſeth the reſt of it as it ſubmergeth & deſcends
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              neath the Surface of the water, which maketh Ramperts and Banks
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              round about it, and it ſuſtaines this loſs by means of its drawing after it,
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              and carrying along with it, the Air that is above it, and by Contact
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              herent to it, which Air ſucceeds to fill the Cavity that is invironed by
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              the Ramperts of water: ſo that that which in this caſe deſcends and is
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              placed in the water, is not only the Board of Ebony or Plate of Iron, </s>
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