Ibn-al-Haitam, al-Hasan Ibn-al-Hasan; Witelo; Risner, Friedrich, Opticae thesavrvs Alhazeni Arabis libri septem, nunc primùm editi. Eivsdem liber De Crepvscvlis & Nubium ascensionibus. Item Vitellonis Thuvringopoloni Libri X. Omnes instaurati, figuris illustrati & aucti, adiectis etiam in Alhazenum commentarijs, a Federico Risnero, 1572

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        <div xml:id="echoid-div560" type="section" level="0" n="0">
          <p>
            <s xml:id="echoid-s17083" xml:space="preserve">
              <pb o="242" file="0248" n="248" rhead="ALHAZEN"/>
            ad partẽ perpendicularis ſuper ſuperficiem corporis diaphani extẽſæ in corpore groſsiore.</s>
            <s xml:id="echoid-s17084" xml:space="preserve"> Cauſſa
              <lb/>
            autem, quæ facit refractionem lucis à corpore groſsiore ad corpus ſubtilius ad partem contrariam
              <lb/>
            parti perpẽdicularis, eſt:</s>
            <s xml:id="echoid-s17085" xml:space="preserve"> quia cum lux mota fuerit in corpore diaphano, repellet eam aliqua repul-
              <lb/>
            ſione, & corpus groſsius repellet eam maiore repulſione, ſicut lapis, cũ mouetur in aere, mouetur
              <lb/>
            facilius & uelocius, quàm ſi moueretur in aqua:</s>
            <s xml:id="echoid-s17086" xml:space="preserve"> eò quòd aqua repellit ipſum maiore repulſione,
              <lb/>
            quàm aer.</s>
            <s xml:id="echoid-s17087" xml:space="preserve"> Cum ergo lux exierit à corpore groſsiore in ſubtilius:</s>
            <s xml:id="echoid-s17088" xml:space="preserve"> tunc motus eius erit uelocior.</s>
            <s xml:id="echoid-s17089" xml:space="preserve"> Et
              <lb/>
            cum lux fuerit obliqua ſuper duas ſuperficies corporis diaphani, quod eſt differentia cõmunis am-
              <lb/>
            bobus corporibus:</s>
            <s xml:id="echoid-s17090" xml:space="preserve"> tunc motus eius erit ſuper lineam exiſtẽtem inter perpendicularem, exeuntem
              <lb/>
            à principio motus eius, & inter perpendicularem ſuper lineam perpendicularem, exeuntem etiam
              <lb/>
            à principio motus.</s>
            <s xml:id="echoid-s17091" xml:space="preserve"> Reſiſtentia ergo corporis groſsioris erit à parte, ad quam exit ſecunda perpen-
              <lb/>
            dicularis.</s>
            <s xml:id="echoid-s17092" xml:space="preserve"> Cum ergo lux exiuerit à corpore groſsiore, & peruenerit ad corpus ſubtilius:</s>
            <s xml:id="echoid-s17093" xml:space="preserve"> tunc reſi-
              <lb/>
            ſtentia corporis ſubtilioris facta luci, quæ eſt in parte, ad quam ſecunda exit perpendicularis, erit
              <lb/>
            minor prima reſiſtentia:</s>
            <s xml:id="echoid-s17094" xml:space="preserve"> & fit motus lucis ad partem, à qua reſiſtebatur, maior.</s>
            <s xml:id="echoid-s17095" xml:space="preserve"> Et ſic eſt de luce in
              <lb/>
            corpore ſubtiliore ad partem contrariam parti perpendicularis.</s>
            <s xml:id="echoid-s17096" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div562" type="section" level="0" n="0">
          <head xml:id="echoid-head488" xml:space="preserve">DE QVALITATE REFRACTIONIS LVCIS IN
            <lb/>
          corporibus diaphanis. Cap. III.</head>
          <head xml:id="echoid-head489" xml:space="preserve" style="it">9. Superficies refractionis eſt perpendicularis ſuperficiei refractiui. 2 p 10.</head>
          <p>
            <s xml:id="echoid-s17097" xml:space="preserve">IN prædicto capitulo [5 n] declaratũ eſt, quòd omnis lux, quæ reſringitur à corpore diaphano
              <lb/>
            ad aliud corpus diaphanum, ſemper erit in una ſuperficie æquali.</s>
            <s xml:id="echoid-s17098" xml:space="preserve"> Linea ergo recta, per quã ex-
              <lb/>
            tenditur lux in aere, & linea recta, per quam refringitur in aqua, ſemper erũt in eadem ſuperficie
              <lb/>
            æquali.</s>
            <s xml:id="echoid-s17099" xml:space="preserve"> Hæc autem ſuperficies apud ιnſpectionem inſtrumenti prædicti, eſt medius circulus ille ex
              <lb/>
            tribus ſignatis in interiore parte oræ inſtrumẽti & ille circulus eſt æquidiſtans ſuperficiei interio-
              <lb/>
            ris laminæ:</s>
            <s xml:id="echoid-s17100" xml:space="preserve"> ſed ſuperficies interioris laminæ eſt æquidiſtans ſuperficiei dorſi, cui ſuperponitur ſu-
              <lb/>
            perficies regulæ quadratæ:</s>
            <s xml:id="echoid-s17101" xml:space="preserve"> ergo ſuperficies circuli medij eſt æquidiſtãs ſuperficiei regulæ quadra-
              <lb/>
            tæ:</s>
            <s xml:id="echoid-s17102" xml:space="preserve"> & ſuperficies regulæ quadratæ, quæ eſt ſuperpoſita dorſo laminæ, eſt perpendicularis ſuper al-
              <lb/>
            teram ſuperficiem, ſecantem ſuperficiem ſuperpoſitam:</s>
            <s xml:id="echoid-s17103" xml:space="preserve"> & hæc ſuperficies regulæ ſuperponitur ſu-
              <lb/>
            perficiei duarum differẽtiarum ſibi applicatarum in duabus extremitatibus regulæ:</s>
            <s xml:id="echoid-s17104" xml:space="preserve"> ſed ſuperficies
              <lb/>
            duarum differentiarum ſuperponitur oræ inſtrumenti.</s>
            <s xml:id="echoid-s17105" xml:space="preserve"> Ergo ſuperficies medij circuli eſt perpen-
              <lb/>
            dicularis ſuper ſuperficiem tranſeuntem ſuper oram inſtrumenti.</s>
            <s xml:id="echoid-s17106" xml:space="preserve"> Et hæc ſuperficies tranſiens per
              <lb/>
            oram inſtrumenti, eſt æquidiſtans horizonti apud experimẽtationem.</s>
            <s xml:id="echoid-s17107" xml:space="preserve"> Superficies ergo medij cir-
              <lb/>
            culi eſt perpendicularis ſuper ſuperficiem horizontis.</s>
            <s xml:id="echoid-s17108" xml:space="preserve"> Cum ergo declaratũ ſit [4.</s>
            <s xml:id="echoid-s17109" xml:space="preserve"> 7.</s>
            <s xml:id="echoid-s17110" xml:space="preserve"> 8 n] quòd lux,
              <lb/>
            quæ eſt in aere, & refringitur in aqua, eſt apud experim entationem in circumferẽtia medij circuli:</s>
            <s xml:id="echoid-s17111" xml:space="preserve">
              <lb/>
            manifeſtum, quòd lux, quę extenditur in aere, & refringitur in aqua, eſt ſemper in eadem ſuperficie
              <lb/>
            æquali ſuper ſuperficiem horizontis.</s>
            <s xml:id="echoid-s17112" xml:space="preserve"> Et etiam imaginemur lineam à
              <lb/>
              <figure xlink:label="fig-0248-01" xlink:href="fig-0248-01a" number="213">
                <variables xml:id="echoid-variables200" xml:space="preserve">a d c g b e f</variables>
              </figure>
            centro medij circuli ad centrum mundi:</s>
            <s xml:id="echoid-s17113" xml:space="preserve"> ſic ergo linea hæc erit per-
              <lb/>
            pendicularis ſuper ſuperficiem aquæ [ut oſtenſum eſt 25 n 4] quia
              <lb/>
            eſt diameter mundi:</s>
            <s xml:id="echoid-s17114" xml:space="preserve"> ſed hęc linea eſt in ſuperficie medij circuli:</s>
            <s xml:id="echoid-s17115" xml:space="preserve"> ergo
              <lb/>
            eſt in ſuperficie refractionis.</s>
            <s xml:id="echoid-s17116" xml:space="preserve"> Ergo ſuperficies refractionis eſt perpen
              <lb/>
            dicularis ſuper ſuperficiem aquæ.</s>
            <s xml:id="echoid-s17117" xml:space="preserve"> Et iam declaratũ eſt, quòd cũ lux
              <lb/>
            refringitur ex aere ad aquam:</s>
            <s xml:id="echoid-s17118" xml:space="preserve"> erit inter primam lineã, per quã exten-
              <lb/>
            ditur in aere, quæ eſt inter diametrũ medij circuli, & inter perpendi-
              <lb/>
            cularem, exeuntẽ à cẽtro medij circuli ſuper ſuperficiẽ aquæ.</s>
            <s xml:id="echoid-s17119" xml:space="preserve"> Et iam
              <lb/>
            declaratum eſt etiã, quòd lux, quæ eſt in puncto, quod eſt centrũ lu-
              <lb/>
            cis, quæ eſt intra aquã, non peruenit ad ipſum, niſi ex luce, quæ extẽ
              <lb/>
            ditur à cẽtro medij circuli.</s>
            <s xml:id="echoid-s17120" xml:space="preserve"> Lux ergo, quę refringitur ex aere ad aquã,
              <lb/>
            refringitur in ſuperficie perpendiculari ſuper ſuperficiẽ aquæ.</s>
            <s xml:id="echoid-s17121" xml:space="preserve"> Et re-
              <lb/>
            fractio eius erit ad partẽ perpẽdicularis exeuntis à loco refractionis
              <lb/>
            ſuper ſuperficiẽ aquæ & nõ perueniet ad perpendicularẽ.</s>
            <s xml:id="echoid-s17122" xml:space="preserve"> Refractio
              <lb/>
            autẽ lucis ab aere ad uitrũ hoc modo fit.</s>
            <s xml:id="echoid-s17123" xml:space="preserve"> Declaratũ eſt enim in expe-
              <lb/>
            rimentatione uitri, quòd cũ linea, quæ tranſit per centra duorũ fora-
              <lb/>
            minũ, fuerit obliqua ſuper ſuperficiẽ uitri æqualẽ, & tranſiuerit per
              <lb/>
            centrũ uitri, & ſuperficies uitri æqualis fuerit ex parte foraminum:</s>
            <s xml:id="echoid-s17124" xml:space="preserve">
              <lb/>
            tunc refringetur apud centrũ uitri:</s>
            <s xml:id="echoid-s17125" xml:space="preserve"> & refractio eius erit in ſuperficie
              <lb/>
            circuli medij ad partẽ, in qua eſt perpendicularis, exiens à cẽtro uitri
              <lb/>
            ſuper ſuperficiẽ uitri æqualẽ.</s>
            <s xml:id="echoid-s17126" xml:space="preserve"> Et declaratũ eſt etiã, quòd cũ linea, quę
              <lb/>
            tranſit per cẽtra duorũ foraminũ, fuerit obliqua ſuper ſuperficiẽ ui-
              <lb/>
            tri ſphæricã:</s>
            <s xml:id="echoid-s17127" xml:space="preserve"> & ſuperficies ſphærica fuerit ex parte foraminũ:</s>
            <s xml:id="echoid-s17128" xml:space="preserve"> tũc lux
              <lb/>
            refringetur in corpore uitri, & apud ſuperficiẽ uitri ſphæricã:</s>
            <s xml:id="echoid-s17129" xml:space="preserve"> & erit
              <lb/>
            refractio eius in ſuperficie medij circuli, & ad partẽ perpendicularis,
              <lb/>
            exeuntis à loco refractionis ſuper ſuperficiẽ uitri ſphæricam.</s>
            <s xml:id="echoid-s17130" xml:space="preserve"> Et ſu-
              <lb/>
            perficies uitri æqualis, in qua eſt centrũ uitrei circuli, eſt perpendi-
              <lb/>
            cularis ſuper ſuperficiem laminæ.</s>
            <s xml:id="echoid-s17131" xml:space="preserve"> Eſt ergo perpendicularis ſuper ſu-
              <lb/>
            perficiem medij circuli.</s>
            <s xml:id="echoid-s17132" xml:space="preserve"> Superficies ergo medij circuli eſt perpendicularis ſuper ſuperficiem uitri
              <lb/>
            </s>
          </p>
        </div>
      </text>
    </echo>