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

Table of Notes

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            <s xml:id="echoid-s9048" xml:space="preserve">IV. </s>
            <s xml:id="echoid-s9049" xml:space="preserve">Patet curvam propoſitam eſſe convexam, aut concavam ad
              <lb/>
            eaſdem partes (convexam verſus partes ſuperiores vel exteriores AY,
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            concavam introrſum, aut deorſum verſus AZZ) nam hoc ipſum,
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            fore convexum aut concavum ad eaſdem partes, nil omnino deſignat
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            aliud, quàm à nulla recta linea præterquam duobus punctis ſecari;
              <lb/>
            </s>
            <s xml:id="echoid-s9050" xml:space="preserve">nec aliò recidit, quam initio libri de ſphæra & </s>
            <s xml:id="echoid-s9051" xml:space="preserve">cylindro tradit _Ar-_
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            _chimedes,_ lineæ ad eaſdem partes cavæ definitio. </s>
            <s xml:id="echoid-s9052" xml:space="preserve">Perſpicuum eſt
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            v. </s>
            <s xml:id="echoid-s9053" xml:space="preserve">g. </s>
            <s xml:id="echoid-s9054" xml:space="preserve">ut linea MN duobus in punctis M, N curvam MNO ſecans ei
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            rurſus occurrat, ut puta in K, debere curvam MNO reflecti, ver-
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            ſùſque partes AY recurvari; </s>
            <s xml:id="echoid-s9055" xml:space="preserve">id quod modò demonſtratum eſt non
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            poſſe contingere. </s>
            <s xml:id="echoid-s9056" xml:space="preserve">Quapropter ipſa linea verſus eaſdem partes con-
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            vexa eſt, ſeu concava.</s>
            <s xml:id="echoid-s9057" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s9058" xml:space="preserve">V. </s>
            <s xml:id="echoid-s9059" xml:space="preserve">Apertiſſimè conſtat lineas quaſvis rectas (ut BZ, CZ) gene-
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            trici AZ parallelas propoſitam curvam ſecare (modò contineantur
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            intra terminos motûs per AY; </s>
            <s xml:id="echoid-s9060" xml:space="preserve">quia curva per harum quamvis inde-
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            finitè promotam deſcripta cenſetur) addo quod harum quælibet cur-
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            vam in uno tantùm puncto ſecat.</s>
            <s xml:id="echoid-s9061" xml:space="preserve">‖ Id patet, quia recta genetrix
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            AZ per unicum duntaxat inſtans temporis durat in ſitu quovis uno,
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            ſeu BZ; </s>
            <s xml:id="echoid-s9062" xml:space="preserve">ſimúlque pertingit ipſam BZ, ac deſerit; </s>
            <s xml:id="echoid-s9063" xml:space="preserve">prætérque
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            punctum unum M in BMZ reliqua cuncta lineæ curvæ puncta ſunt
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              <note position="right" xlink:label="note-0209-01" xlink:href="note-0209-01a" xml:space="preserve">Apoll. I. 26.
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              Arch. de Con
                <unsure/>
              @id.
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              & Sph. 16.</note>
            in parallelis ad BZ. </s>
            <s xml:id="echoid-s9064" xml:space="preserve">Ergò liquidum eſt ipſam BZ in uno tantùm
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            puncto curvam ſecare.</s>
            <s xml:id="echoid-s9065" xml:space="preserve">‖ Hocipſum de parabola, & </s>
            <s xml:id="echoid-s9066" xml:space="preserve">hiperbola ſpecia-
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            tim oſtendit _Apollonius_; </s>
            <s xml:id="echoid-s9067" xml:space="preserve">de ſectionibus conoideon _Arcbimedes_.</s>
            <s xml:id="echoid-s9068" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s9069" xml:space="preserve">VI. </s>
            <s xml:id="echoid-s9070" xml:space="preserve">Non diſſimili modo patet ad AY parallelam quamvis, (qualis
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            PG) unico puncto propoſitam curvam attingere.</s>
            <s xml:id="echoid-s9071" xml:space="preserve">‖ Quòd ſemel
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            occurret (modò contineatur intra limites deſcensûs per AZ) patet,
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            quia punctum mobile continuò deſcendens, indefinito progreſſu, eam
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            indefinitè protenſam aliquando trajiciet; </s>
            <s xml:id="echoid-s9072" xml:space="preserve">nec in eo tamen præterquam
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              <note position="right" xlink:label="note-0209-02" xlink:href="note-0209-02a" xml:space="preserve">I. 19.</note>
            ad unum temporis momentum perdurat.</s>
            <s xml:id="echoid-s9073" xml:space="preserve">‖ Videatur hoc de ſectioni-
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            bus conicis oſtendens _Apollonius_.</s>
            <s xml:id="echoid-s9074" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s9075" xml:space="preserve">VII. </s>
            <s xml:id="echoid-s9076" xml:space="preserve">Patet omnes curvæ ſubtenſas rectas cum AZ & </s>
            <s xml:id="echoid-s9077" xml:space="preserve">ei parallelis,
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            ſi producantur, concurrere.</s>
            <s xml:id="echoid-s9078" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s9079" xml:space="preserve">Quòd enim ſubtenſa quævis, ut MN, uni parallelarum alicui, ut
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            BR, occurrit, ibi ſcilicet ubi ipſa curvam ſecat, exinde manifeſtiſſimum
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            eſt, quòd tota curva per parallelum dictæ rectæ motum deſcribitur.
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            </s>
            <s xml:id="echoid-s9080" xml:space="preserve">Ergò, cùm uni occurrat, omnibus occurret; </s>
            <s xml:id="echoid-s9081" xml:space="preserve">quæ enim uni </s>
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