Salusbury, Thomas, Mathematical collections and translations (Tome I), 1667

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      <text>
        <body>
          <chap>
            <p type="main">
              <s>
                <pb xlink:href="040/01/229.jpg" pagenum="211"/>
              principle, ſeeing that if it be not hindered, it moveth
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              ouſly: and on the contrary, I know that the principle which
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              veth it upwards, is external, although that I do not know, what
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              thing that vertue is, impreſſed on it by the projicient.</s>
            </p>
            <p type="main">
              <s>SALV. </s>
              <s>Into how many queſtions muſt we excurre, if we would
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              decide all the difficulties, which ſucceſſively have dependance one
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              upon another! You call that an external (and you alſo call it a
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              preternatural and violent) principle, which moveth the grave
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              ject upwards; but its poſſible that it may be no leſſe interne and
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              natural, than that which moveth it downwards; it may
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                <arrow.to.target n="marg416"/>
                <lb/>
              ture be called external and violent, ſo long as the moveable is
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              ned to the projicient; but being ſeparated, what external thing
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              remaineth for a mover of the arrow, or ball? </s>
              <s>In ſumme, it muſt
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              neceſſarliy be granted, that that vertue which carrieth ſuch a
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              able upwards, is no leſſe interne, than that which moveth it
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              wards; and I think the motion of grave bodies aſcending by the
                <lb/>
                <emph type="italics"/>
              impetus
                <emph.end type="italics"/>
              conceived, to be altogether as natural, as the motion of
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              deſcent depending on gravity.</s>
            </p>
            <p type="margin">
              <s>
                <margin.target id="marg416"/>
                <emph type="italics"/>
              The vertue which
                <lb/>
              carrieth grave
                <lb/>
              jects upwards, is
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              no leſſe natural to
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              them, than the
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              gravity which
                <lb/>
              veth them
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              wards.
                <emph.end type="italics"/>
              </s>
            </p>
            <p type="main">
              <s>SIMP. </s>
              <s>I will never grant this; for the motion of deſcent hath
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              its principle internal, natural, and perpetual, and the motion of
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              aſcent hath its principle externe, violent, and finite.</s>
            </p>
            <p type="main">
              <s>SALV. </s>
              <s>If you refuſe to grant me, that the principles of the
                <lb/>
              motions of grave bodies downwards and upwards, are equally
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                <arrow.to.target n="marg417"/>
                <lb/>
              ternal and natural; what would you do, if I ſhould ſay, that they
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              may alſo be the ſame in number?</s>
            </p>
            <p type="margin">
              <s>
                <margin.target id="marg417"/>
                <emph type="italics"/>
              Contrary
                <lb/>
              ciples cannot
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              rally reſide in the
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              ſame ſubject.
                <emph.end type="italics"/>
              </s>
            </p>
            <p type="main">
              <s>SIMP. </s>
              <s>I leave it to you to judge.</s>
            </p>
            <p type="main">
              <s>SALV. </s>
              <s>But I deſire you your ſelf to be the Judge: Therefore
                <lb/>
              tell me, Do you believe that in the ſame natural body, there may
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              reſide interne principles, that are contrary to one another?</s>
            </p>
            <p type="main">
              <s>SIMP. </s>
              <s>I do verily believe there cannot.</s>
            </p>
            <p type="main">
              <s>SALV. </s>
              <s>What do you think to be the natural inclination of
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              Earth, of Lead, of Gold, and in ſum, of the moſt ponderous
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              ters; that is, to what motion do you believe that their interne
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              principle draweth them?</s>
            </p>
            <p type="main">
              <s>SIMP. </s>
              <s>To that towards the centre of things grave, that is, to
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              the centre of the Univerſe, and of the Earth, whither, if they be
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              not hindered, it will carry them.</s>
            </p>
            <p type="main">
              <s>SALV. </s>
              <s>So that, if the Terreſtrial Globe were bored thorow,
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              and a Well made that ſhould paſſe through the centre of it, a
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              Cannon bullet being let fall into the ſame, as being moved by a
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              natural and intrinſick principle, would paſſe to the centre; and it
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              would make all this motion ſpontaneouſly, and by intrinſick
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              ciple, is it not ſo?</s>
            </p>
            <p type="main">
              <s>SIMP. </s>
              <s>So I verily believe.</s>
            </p>
            <p type="main">
              <s>SALV. </s>
              <s>But when it is arrived at the centre, do you think that </s>
            </p>
          </chap>
        </body>
      </text>
    </archimedes>
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