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

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          <p>
            <s xml:id="echoid-s2770" xml:space="preserve">
              <pb o="50" file="0068" n="68" rhead=""/>
            BVT, patet rectam VT angulum XVC ſecare. </s>
            <s xml:id="echoid-s2771" xml:space="preserve">item ob angulum
              <lb/>
            XYV obtuſum, eſt XV &</s>
            <s xml:id="echoid-s2772" xml:space="preserve">gt; </s>
            <s xml:id="echoid-s2773" xml:space="preserve">XY = BX. </s>
            <s xml:id="echoid-s2774" xml:space="preserve">ergo BV &</s>
            <s xml:id="echoid-s2775" xml:space="preserve">gt; </s>
            <s xml:id="echoid-s2776" xml:space="preserve">2 BX; </s>
            <s xml:id="echoid-s2777" xml:space="preserve">& </s>
            <s xml:id="echoid-s2778" xml:space="preserve">
              <lb/>
            VT &</s>
            <s xml:id="echoid-s2779" xml:space="preserve">gt; </s>
            <s xml:id="echoid-s2780" xml:space="preserve">2 XD. </s>
            <s xml:id="echoid-s2781" xml:space="preserve">Verùm ang. </s>
            <s xml:id="echoid-s2782" xml:space="preserve">VTC (major ipſo TVB, vel ipſo
              <lb/>
            DXB) eſt obtuſus; </s>
            <s xml:id="echoid-s2783" xml:space="preserve">adeóque VC &</s>
            <s xml:id="echoid-s2784" xml:space="preserve">gt; </s>
            <s xml:id="echoid-s2785" xml:space="preserve">VT; </s>
            <s xml:id="echoid-s2786" xml:space="preserve">itàque magìs YC &</s>
            <s xml:id="echoid-s2787" xml:space="preserve">gt;
              <lb/>
            </s>
            <s xml:id="echoid-s2788" xml:space="preserve">2 X D. </s>
            <s xml:id="echoid-s2789" xml:space="preserve">ergò AB + AY + YC &</s>
            <s xml:id="echoid-s2790" xml:space="preserve">gt; </s>
            <s xml:id="echoid-s2791" xml:space="preserve">2 AX + 2 XD. </s>
            <s xml:id="echoid-s2792" xml:space="preserve">hoc eſt
              <lb/>
            AB + AC &</s>
            <s xml:id="echoid-s2793" xml:space="preserve">gt; </s>
            <s xml:id="echoid-s2794" xml:space="preserve">2 AD : </s>
            <s xml:id="echoid-s2795" xml:space="preserve">Q. </s>
            <s xml:id="echoid-s2796" xml:space="preserve">E. </s>
            <s xml:id="echoid-s2797" xml:space="preserve">D.</s>
            <s xml:id="echoid-s2798" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s2799" xml:space="preserve">XV. </s>
            <s xml:id="echoid-s2800" xml:space="preserve">Quò paralleli radii rectiùs (vel axi propinquiùs) incidunt,
              <lb/>
            eò reflexorum concurſus ad axem ſibi viciniores ſunt.</s>
            <s xml:id="echoid-s2801" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s2802" xml:space="preserve">Nempe ſumantur utcunque pares arcus NR, RX; </s>
            <s xml:id="echoid-s2803" xml:space="preserve">& </s>
            <s xml:id="echoid-s2804" xml:space="preserve">incidentium
              <lb/>
              <note position="left" xlink:label="note-0068-01" xlink:href="note-0068-01a" xml:space="preserve">Fig. 67.</note>
            MN, QR, VX reflexi NK, RL, XM cum axe conveniant punctis
              <lb/>
            K, L, M, erit ML &</s>
            <s xml:id="echoid-s2805" xml:space="preserve">gt; </s>
            <s xml:id="echoid-s2806" xml:space="preserve">LK. </s>
            <s xml:id="echoid-s2807" xml:space="preserve">Nam connexæ CN, CR, CX rectæ
              <lb/>
            ZY occurrant punctis v, ρ, ξ. </s>
            <s xml:id="echoid-s2808" xml:space="preserve">Eſt itaque (juxta _Lemma_ præcedens)
              <lb/>
            C ξ + Cv &</s>
            <s xml:id="echoid-s2809" xml:space="preserve">gt; </s>
            <s xml:id="echoid-s2810" xml:space="preserve">2C ρ; </s>
            <s xml:id="echoid-s2811" xml:space="preserve">hoc eſt, CM + CK &</s>
            <s xml:id="echoid-s2812" xml:space="preserve">gt; </s>
            <s xml:id="echoid-s2813" xml:space="preserve">2 CL. </s>
            <s xml:id="echoid-s2814" xml:space="preserve">quare CM
              <lb/>
            - CL &</s>
            <s xml:id="echoid-s2815" xml:space="preserve">gt; </s>
            <s xml:id="echoid-s2816" xml:space="preserve">CL - CK; </s>
            <s xml:id="echoid-s2817" xml:space="preserve">hoceſt ML &</s>
            <s xml:id="echoid-s2818" xml:space="preserve">gt; </s>
            <s xml:id="echoid-s2819" xml:space="preserve">LK: </s>
            <s xml:id="echoid-s2820" xml:space="preserve">Q. </s>
            <s xml:id="echoid-s2821" xml:space="preserve">E. </s>
            <s xml:id="echoid-s2822" xml:space="preserve">D.</s>
            <s xml:id="echoid-s2823" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s2824" xml:space="preserve">XVI. </s>
            <s xml:id="echoid-s2825" xml:space="preserve">Exhinc patet axi propinquam lucem ab hujuſmodi reflectione
              <lb/>
            magìs magíſque conſtipari; </s>
            <s xml:id="echoid-s2826" xml:space="preserve">maximè circa punctum Z, ubi perpendi-
              <lb/>
            cularis ipſius quaſi reflexus terminatur. </s>
            <s xml:id="echoid-s2827" xml:space="preserve">unde potiſſima conſtat ratio,
              <lb/>
            quare concavis à ſpeculis ad ſolem expoſitis
              <unsure/>
            circa punctum Z _Ignis_
              <lb/>
            accenditur; </s>
            <s xml:id="echoid-s2828" xml:space="preserve">e
              <unsure/>
            nimverò condenſatior, ínque ſpacium arctius quaſi com-
              <lb/>
            preſſa lux validiorem exerit vim, ac efficaciam.</s>
            <s xml:id="echoid-s2829" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s2830" xml:space="preserve">XVII. </s>
            <s xml:id="echoid-s2831" xml:space="preserve">Quinetiam ex his conſectatur, longinqui puncti imaginem
              <lb/>
            oculo in axe conſtitnta circa punctum Z conſiſtere. </s>
            <s xml:id="echoid-s2832" xml:space="preserve">Sit, inquam,
              <lb/>
              <note position="left" xlink:label="note-0068-02" xlink:href="note-0068-02a" xml:space="preserve">Fig. 68.</note>
            BCO axis Opticns; </s>
            <s xml:id="echoid-s2833" xml:space="preserve">oculíque dìameter D δ (in plana nempe cir-
              <lb/>
            culi propoſiti ſita) hujus autem extrema permeent reflexi NKD,
              <lb/>
            VK δ (ad incidentes MN P, μ ν Π pertinentes) . </s>
            <s xml:id="echoid-s2834" xml:space="preserve">jam abunde mani-
              <lb/>
            feſtum eſt imaginem conſpicuam intra KZ ſpatium verſari. </s>
            <s xml:id="echoid-s2835" xml:space="preserve">Nam
              <lb/>
            alterius cujuſvis hinc, vel indè cadentis reflexus (ſeu ipſius R S, vel
              <lb/>
            ρ σ) oculum omnino transgredietur, adeóque nihil quicquam ad viſio-
              <lb/>
            nem ipſam, vel ad ejus quemcunque modum determinandum conferet;
              <lb/>
            </s>
            <s xml:id="echoid-s2836" xml:space="preserve">id autem omne meritó tribuetur radiorum intra peripheriam NV in-
              <lb/>
            cidentium reflexis; </s>
            <s xml:id="echoid-s2837" xml:space="preserve">qui ſcilicet oculum ingredientes ſuo quiſque modo
              <lb/>
            viſum aliquatenus afficiant. </s>
            <s xml:id="echoid-s2838" xml:space="preserve">quoniam tamen ex his, qui propiores
              <lb/>
            axi rectiùs incidunt oculo, magíſque pollent idcircò; </s>
            <s xml:id="echoid-s2839" xml:space="preserve">nec non iidem
              <lb/>
            proptergà faciliùs ad unum in oculo punctum recolliguntur; </s>
            <s xml:id="echoid-s2840" xml:space="preserve">præ cæte-
              <lb/>
            ris etiam illi catervatim ingruunt; </s>
            <s xml:id="echoid-s2841" xml:space="preserve">rationi conſonum eſt iſthic præſer-
              <lb/>
            tim imaginem conſiſtere; </s>
            <s xml:id="echoid-s2842" xml:space="preserve">ſiquidem velut ab eo plures, ac efficaciſſimi
              <lb/>
            radii videbuntur cmanare, Subjicio, propter admodum exiguam </s>
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