Barrow, Isaac, Lectiones opticae & geometricae : in quibus phaenomenon opticorum genuinae rationes investigantur, ac exponuntur: et generalia curvarum linearum symptomata declarantur
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            <s xml:id="echoid-s8096" xml:space="preserve">
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            concentricos expoſitis repræſentandis inſervire. </s>
            <s xml:id="echoid-s8097" xml:space="preserve">nimirum in caſu po-
              <lb/>
            ſtremo, ſi reliquis ſtantibus punctum A indeterminatum ponatur, ni-
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            hilominus hyperbolæ ζυζ, YTY rectas FAG repræſentabunt ad
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            circulos, quorum ſemidiametri CB ipſis AI ſingulæ reſpectivæ
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            ſingulis æ quantur, modò ſemper intelligatur eſſe CA. </s>
            <s xml:id="echoid-s8098" xml:space="preserve">CR:</s>
            <s xml:id="echoid-s8099" xml:space="preserve">: I. </s>
            <s xml:id="echoid-s8100" xml:space="preserve">R.
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            </s>
            <s xml:id="echoid-s8101" xml:space="preserve">id quod ſatìs fuerit obiter admonuiſſe.</s>
            <s xml:id="echoid-s8102" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s8103" xml:space="preserve">VIII. </s>
            <s xml:id="echoid-s8104" xml:space="preserve">Ut & </s>
            <s xml:id="echoid-s8105" xml:space="preserve">illud curſim innuiſſe ſuſſecerit, quòd ſicut à conicis
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            ſectionibus rectæ lineæ, ita viciſſim _conicæ ſectiones_ à rectis lineis ex
              <lb/>
            juſta congruos ad circulos inſlectione repræſentantur; </s>
            <s xml:id="echoid-s8106" xml:space="preserve">quos utique
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            non arduum videtur è præmiſſis deducere.</s>
            <s xml:id="echoid-s8107" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s8108" xml:space="preserve">IX. </s>
            <s xml:id="echoid-s8109" xml:space="preserve">Ut & </s>
            <s xml:id="echoid-s8110" xml:space="preserve">exindè _datâ conicâ ſe
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            ctione_ circulus & </s>
            <s xml:id="echoid-s8111" xml:space="preserve">recta facilè deſignan-
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            tur, ità ut conica rectam illam repræſentet ex inſlectione ad iſtum
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            circulum. </s>
            <s xml:id="echoid-s8112" xml:space="preserve">Nempe ſi à foco C ad axem CV applicetur normalis
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            CE; </s>
            <s xml:id="echoid-s8113" xml:space="preserve">& </s>
            <s xml:id="echoid-s8114" xml:space="preserve">recta ER ſectionem tangat ad E; </s>
            <s xml:id="echoid-s8115" xml:space="preserve">factoque CR. </s>
            <s xml:id="echoid-s8116" xml:space="preserve">CA:</s>
            <s xml:id="echoid-s8117" xml:space="preserve">:
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            R. </s>
            <s xml:id="echoid-s8118" xml:space="preserve">I; </s>
            <s xml:id="echoid-s8119" xml:space="preserve">ducatur per A recta AI ad CE parallela; </s>
            <s xml:id="echoid-s8120" xml:space="preserve">sitque CB = AI;
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            </s>
            <s xml:id="echoid-s8121" xml:space="preserve">tum centro C per B ducatur circulus MBN, peractum erit nego-
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            tium.</s>
            <s xml:id="echoid-s8122" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s8123" xml:space="preserve">X. </s>
            <s xml:id="echoid-s8124" xml:space="preserve">Ex his tandem de imaginibus ad oculum ubicunque collocatum
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            relatis, quales illæ figuras ac ſitus obtinent, proclivius erit judicare.
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            </s>
            <s xml:id="echoid-s8125" xml:space="preserve">ſcilicet eæ ſaltem unum (in recta per oculi, circulique reſringentis
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            centrum trajecta poſitum) commune cum abſolutis punctum habent; </s>
            <s xml:id="echoid-s8126" xml:space="preserve">
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            quoad reliqua vero reſpectiva puncta nonnihil ab his deſlectunt ad eas
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            partes, quas oculi ſitus peculiaris, & </s>
            <s xml:id="echoid-s8127" xml:space="preserve">radiorum curſus exigunt; </s>
            <s xml:id="echoid-s8128" xml:space="preserve">id
              <lb/>
            quod facilius ſit in ſingulis caſibus qualiter eveniat perſpicere, quam
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            verbis univerſim explicare. </s>
            <s xml:id="echoid-s8129" xml:space="preserve">ſed enim unam rei declarandæ ſubjicie-
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            mus inſtantiam. </s>
            <s xml:id="echoid-s8130" xml:space="preserve">Ad oculum O refringantur ab F, & </s>
            <s xml:id="echoid-s8131" xml:space="preserve">G radii FMO,
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            GNO; </s>
            <s xml:id="echoid-s8132" xml:space="preserve">ſit autem _ellipſis_ TZVY rectæ FG abſoluta imago, quam
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            connexæ FC, GC punctis Z, Y ſecent (ità quidem ut Z ſit puncti F,
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              <note position="left" xlink:label="note-0142-01" xlink:href="note-0142-01a" xml:space="preserve">Fig. 201.</note>
            & </s>
            <s xml:id="echoid-s8133" xml:space="preserve">Y puncti G imago abſoluta) enimverò, de ſupradictis colligitur
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            punctum K ſupra Z verſus C exiſtere; </s>
            <s xml:id="echoid-s8134" xml:space="preserve">quinetiam puncti F in recta
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            MO imaginem (puta φ) ultra FZ jacere. </s>
            <s xml:id="echoid-s8135" xml:space="preserve">Similiter puncti G ima-
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            go (γ) ſupra Y, ultráque GY ſita eſt. </s>
            <s xml:id="echoid-s8136" xml:space="preserve">unde conjectura ſiet de totius
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            imaginis φ α γ poſitione, ſeu figura ad _ellipticam_ accedente, qualis
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            in appoſita exhibetur figura; </s>
            <s xml:id="echoid-s8137" xml:space="preserve">quæ certè (quanquam haud abſque
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            nimiâ moleſtiâ) juxta theoriam ſuprà conſtabilitam accuratè poterit
              <lb/>
            delineari.</s>
            <s xml:id="echoid-s8138" xml:space="preserve"/>
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