Barrow, Isaac, Lectiones opticae & geometricae : in quibus phaenomenon opticorum genuinae rationes investigantur, ac exponuntur: et generalia curvarum linearum symptomata declarantur

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        <div xml:id="echoid-div220" type="section" level="1" n="30">
          <head xml:id="echoid-head33" xml:space="preserve">
            <emph style="sc">Lect</emph>
          . III.</head>
          <p>
            <s xml:id="echoid-s8873" xml:space="preserve">Q Uomodo per _motus ſimplices progreſſivum, & </s>
            <s xml:id="echoid-s8874" xml:space="preserve">converſivum_
              <lb/>
            _ffectæ concipiantur magnitudines, & </s>
            <s xml:id="echoid-s8875" xml:space="preserve">qualia generationes iſtas_
              <lb/>
            _conſequuntur ſymptomata_ (nonnulla ſaltem præcipua) _con-_
              <lb/>
            _niſi ſumus exponere ad compoſitos nunc, & </s>
            <s xml:id="echoid-s8876" xml:space="preserve">concurrentes,_
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            _eidem propoſito ſervientes, motns accingimur;_ </s>
            <s xml:id="echoid-s8877" xml:space="preserve">quorum in effectis
              <lb/>
            diſcernendis velocitates, ſecundum quas ſimplices peraguntur motus,
              <lb/>
            omnino, vel cum primis conſiderandæ ſunt; </s>
            <s xml:id="echoid-s8878" xml:space="preserve">quarum in generatione
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            per motus ſimplices nulla prorſus habetur ratio. </s>
            <s xml:id="echoid-s8879" xml:space="preserve">Per eundem enim
              <lb/>
            motum ſimplicem ſeu velocior is ſit, ſeu tardior eadem magnitudo,
              <lb/>
            quamvìs non eodem temporis intervallo, producitur; </s>
            <s xml:id="echoid-s8880" xml:space="preserve">idem nempe
              <lb/>
            _circulus_ ex ejuſdem rectæ circa punctum in ea fixum, _eadem Sphæra_
              <lb/>
            ex Semicirculi circa _diametrum_ rotatu; </s>
            <s xml:id="echoid-s8881" xml:space="preserve">quamvìs ut hæc fiant eò ma-
              <lb/>
            gìs awt minus expectandum ſit, quo ſegnior aut citatior ſupponitur ea
              <lb/>
            progenerans motus. </s>
            <s xml:id="echoid-s8882" xml:space="preserve">Verùm in generatione per motus compoſitos
              <lb/>
            iiſdem manentibus lationis modis, prout unius aut plurium variatur
              <lb/>
            velocitas, nedum ſpecie, ſed etiam quantitate diverſæ magnitudines
              <lb/>
            emergere ſolent, poſitione ſaltem perpetuò differentes. </s>
            <s xml:id="echoid-s8883" xml:space="preserve">Ut ſi recta
              <lb/>
              <note position="left" xlink:label="note-0202-01" xlink:href="note-0202-01a" xml:space="preserve">Fig. 13.</note>
            AB per rectam AC parallelo deferatur æquabili motu; </s>
            <s xml:id="echoid-s8884" xml:space="preserve">& </s>
            <s xml:id="echoid-s8885" xml:space="preserve">ſimul
              <lb/>
            punctum M in AB deſcendat uniformiter; </s>
            <s xml:id="echoid-s8886" xml:space="preserve">vel ſimulrecta AC pa-
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            rallelo quoque uniformi motu deſcendens ipſam AB promotam inter-
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            ſecet in M; </s>
            <s xml:id="echoid-s8887" xml:space="preserve">ex ejuſmodi motuum compoſitione vel concurſu produ-
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            cetur recta linea AM. </s>
            <s xml:id="echoid-s8888" xml:space="preserve">Quòd ſi eodem, etiam quoad velocitatem
              <lb/>
            manente motu rectæ AB, immutetur in velocitate motus uniformis
              <lb/>
            puncti M, vel rectæ AC, ità quidem punctum M jam eodem tem-
              <lb/>
            pore pervenerit ad μ, vel AC ſecet ipſam AB in μ, deſcribetur
              <lb/>
            hoc motu alia recta A μ à priore AM poſitione diverſa. </s>
            <s xml:id="echoid-s8889" xml:space="preserve">Sin verò,
              <lb/>
            manente rurſus eodem motu rectæ AB, pro motu puncti M, vel
              <lb/>
            rectæ AC uniformi ſubſtituatur motus, quem vocant, æqualiter
              <lb/>
            acceleratus, ex ejuſmodi compoſitione, vel concurſu fiet </s>
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