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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          <p>
            <s xml:id="echoid-s18764" xml:space="preserve">
              <pb o="270" file="0276" n="276" rhead="ALHAZEN"/>
            uiſum, cum non rectè perueniat ad centrum uiſus.</s>
            <s xml:id="echoid-s18765" xml:space="preserve"> Si ergo uiſus non comprehenderet illud, quod
              <lb/>
            opponitur ex pariete acui, niſi rectè:</s>
            <s xml:id="echoid-s18766" xml:space="preserve"> tunc illud, quod opponitur acui ex pariete, eſſet coopertum à
              <lb/>
            uiſu.</s>
            <s xml:id="echoid-s18767" xml:space="preserve"> Cũ ergo comprehendatur, & non rectè:</s>
            <s xml:id="echoid-s18768" xml:space="preserve"> patet ipſum comprehendi refractè performam, quæ
              <lb/>
            refringitur à lateribus acus ex ſuperficie uiſus.</s>
            <s xml:id="echoid-s18769" xml:space="preserve"> Et hoc iam manifeſtatur etiam, quòd ſi experimẽta-
              <lb/>
            tor poſuerit loco acus aliquod corpus latũ, cuius latitudo ſit maior latitudine foraminis uueæ:</s>
            <s xml:id="echoid-s18770" xml:space="preserve"> tũc
              <lb/>
            enim nihil uidebit omnino de pariete, nec uidebit illud corpus diaphanũ, ſed dẽſum.</s>
            <s xml:id="echoid-s18771" xml:space="preserve"> Ex hoc ergo,
              <lb/>
            quòd paries comprehenditur ultra acum ex gracilitate eius, & non comprehenditur ultra corpus
              <lb/>
            latũ:</s>
            <s xml:id="echoid-s18772" xml:space="preserve"> ſcimus quòd illa comprehẽſio eſt ex forma, quæ peruenit ad acũ ex ſuperficie uilu
              <gap/>
            , & refrin-
              <lb/>
            gitur in tunicis uiſus.</s>
            <s xml:id="echoid-s18773" xml:space="preserve"> Et quia quic quid à uiſu comprehenditur refractè, comprehenditur in rectitu
              <lb/>
            dine perpendicularium:</s>
            <s xml:id="echoid-s18774" xml:space="preserve"> ideo illud, quod comprehẽdit, comprehẽdit refractè ex forma eius, quod
              <lb/>
            opponitur acui per rectitudinem linearũ, exeuntiũ à cẽtro uiſus, cũ eo, quod opponitur acui ex pa
              <lb/>
            riete:</s>
            <s xml:id="echoid-s18775" xml:space="preserve"> & hæ lineæ ſecantur acu, & uiſus comprehendit illud, quod eſt ultra acũ etiam in rectitudine
              <lb/>
            harũ linearũ, & comprehendit acũ etiam in rectitudine illarũ.</s>
            <s xml:id="echoid-s18776" xml:space="preserve"> Quare totam formam quaſi compre-
              <lb/>
            hendet ultra corpus diaphanũ, in quo eſt aliquãtula denſitas.</s>
            <s xml:id="echoid-s18777" xml:space="preserve"> Et ſi experimẽtator ſcripſerit in bom-
              <lb/>
            bace ſubtiliter, & applicauerit ipſum parieti, & remotus fuerit à pariete, in quantũ poſsit legere ſcri
              <lb/>
            pturam, & poſueritacũ in oppoſitione medij uiſus, ut primò fecit, & aſpexerit bombacem:</s>
            <s xml:id="echoid-s18778" xml:space="preserve"> tũc po-
              <lb/>
            terit legere ſcripturam, ſed tamen uidebit eam quaſi ultra uitrũ aut ultra corpus diaphanũ, in quo
              <lb/>
            eſt aliqua dẽſitas.</s>
            <s xml:id="echoid-s18779" xml:space="preserve"> Si ergo uiſus non comprehẽdit illud, quod opponitur acui de bom bace ſecũdum
              <lb/>
            refractionem:</s>
            <s xml:id="echoid-s18780" xml:space="preserve"> tũc aliquid lateret de ſcriptura:</s>
            <s xml:id="echoid-s18781" xml:space="preserve"> acus enim debet cooperire de ſcriptura multò magis
              <lb/>
            ſe in quantitate latitudinis diaphanitatis, quàm tũc comprehendit, propter remotionem bomba-
              <lb/>
            cis à uiſu.</s>
            <s xml:id="echoid-s18782" xml:space="preserve"> Sed quia uiſui non patet aliquid de ſcriptura:</s>
            <s xml:id="echoid-s18783" xml:space="preserve"> patet ipſum comprehẽdere illud, quod op-
              <lb/>
            ponitur acui:</s>
            <s xml:id="echoid-s18784" xml:space="preserve"> ſed hoc non poteſt fieri rectè:</s>
            <s xml:id="echoid-s18785" xml:space="preserve"> reſtat ergo, ut fiat refractè.</s>
            <s xml:id="echoid-s18786" xml:space="preserve"> Et ſi experimẽtator abſtule-
              <lb/>
            rit acum, non deſtruetur refractio, quę prius erat:</s>
            <s xml:id="echoid-s18787" xml:space="preserve"> non enim propter acum erat refractio, fed creſcit
              <lb/>
            refractio, eò quòd refringitur ex loco acus.</s>
            <s xml:id="echoid-s18788" xml:space="preserve"> Et cũ experimẽtator abſtulerit acum:</s>
            <s xml:id="echoid-s18789" xml:space="preserve"> comprehẽdet il-
              <lb/>
            lud, quod opponitur uiſui, manifeſtius.</s>
            <s xml:id="echoid-s18790" xml:space="preserve"> Nam comprehẽdet illud rectè, quod cooperiebatur acu:</s>
            <s xml:id="echoid-s18791" xml:space="preserve"> cũ
              <lb/>
            hoc, quod comprehẽdit illud refractè, ſicut comprehẽdebat cum cooperiebatur:</s>
            <s xml:id="echoid-s18792" xml:space="preserve"> & propter hanc
              <lb/>
            additionem comprehendit illud manifeſtius, quàm antequam auferretacum.</s>
            <s xml:id="echoid-s18793" xml:space="preserve"> Ex qua experientia
              <lb/>
            patet, quòd illud quod opponitur uiſui de illis, quæ ſunt intra pyramidem radialem, comprehẽdi-
              <lb/>
            tur refractè & rectè.</s>
            <s xml:id="echoid-s18794" xml:space="preserve"> Ex his ergo omnibus declaratur, quòd omnia, quæ comprehenduntur à uiſu,
              <lb/>
            quorum formæ perueniunt ad uiſum rectè, aut reflexè, aut refractè:</s>
            <s xml:id="echoid-s18795" xml:space="preserve"> comprehenduntur ſecundum
              <lb/>
            refractionẽ factam apud ſuperficiem uiſus:</s>
            <s xml:id="echoid-s18796" xml:space="preserve"> & quòd illorũ quę comprehendũtur ſecũdum refractio
              <lb/>
            nem factam à ſuperficie uiſus:</s>
            <s xml:id="echoid-s18797" xml:space="preserve"> quædam comprehẽduntur refractè & rectè ſimul:</s>
            <s xml:id="echoid-s18798" xml:space="preserve"> & ideo illud, qđ
              <lb/>
            opponitur medio uiſus, eſt manifeſtius illo, quod eſt in circuitu medij.</s>
            <s xml:id="echoid-s18799" xml:space="preserve"> Et cum uiſus comprehẽde-
              <lb/>
            rit aliquid latum, comprehẽdet illud, quod eft in medio, manifeſtius illo, quod eſt in lateribus.</s>
            <s xml:id="echoid-s18800" xml:space="preserve"> Hoc
              <lb/>
            aũt declaratũ eſt in ſecũ do tractatu, in quo declarauimus, quo modo hoc poſſet experimẽtari:</s>
            <s xml:id="echoid-s18801" xml:space="preserve"> & di
              <lb/>
            ximus, quòd cauſſa huius eſt propter lineas radiales:</s>
            <s xml:id="echoid-s18802" xml:space="preserve"> & hoc eſt in illis, quę ſunt intra pyramidem ra
              <lb/>
            dialẽ:</s>
            <s xml:id="echoid-s18803" xml:space="preserve"> In alijs aũt, quæ ſunt extrà, eſt cauſſa refractio.</s>
            <s xml:id="echoid-s18804" xml:space="preserve"> Cauſſa aũt uniuerſalis in hoc, quòd illud, quod
              <lb/>
            opponitur medio uiſus, eſt manifeſtius, quã illud, quod eſt in circuitu:</s>
            <s xml:id="echoid-s18805" xml:space="preserve"> eſt:</s>
            <s xml:id="echoid-s18806" xml:space="preserve"> quoniã illud quòd oppo
              <lb/>
            nitur medio uiſus, comprehẽditur rectè & refractè ſimul.</s>
            <s xml:id="echoid-s18807" xml:space="preserve"> Hoc aũt, quòd quicquid comprehẽditur
              <lb/>
            à uiſu, comprehendatur refractè, à nullo antiquorum dictum eſt.</s>
            <s xml:id="echoid-s18808" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div606" type="section" level="0" n="0">
          <head xml:id="echoid-head522" xml:space="preserve">DE FALLACIIS VISVS, QVAE ACCIDVNT
            <lb/>
          ex refractione. Cap. VII.</head>
          <head xml:id="echoid-head523" xml:space="preserve" style="it">38. Refractio debilit at lucem & colorem uiſibilis: ita totam imaginem confuſam uiſui of-
            <lb/>
          fert. 10 p 10.</head>
          <p>
            <s xml:id="echoid-s18809" xml:space="preserve">FAllaciæ, quæ accidunt ſecũdum refractionem:</s>
            <s xml:id="echoid-s18810" xml:space="preserve"> ſimiles ſunt ijs, quæ accidunt per reflexionem.</s>
            <s xml:id="echoid-s18811" xml:space="preserve">
              <lb/>
            Quod enim comprehẽditur refractè, comprehẽditur non in ſuo loco, cũ comprehendatur in
              <lb/>
            loco imaginis:</s>
            <s xml:id="echoid-s18812" xml:space="preserve"> quapropter poſitio formæ comprehenſæ erit alia à poſitione rei uiſæ.</s>
            <s xml:id="echoid-s18813" xml:space="preserve"> Item re-
              <lb/>
            fractio debilitat formam refractam, ſcilicet, formam lucis & coloris, quæ ſunt in re uiſa.</s>
            <s xml:id="echoid-s18814" xml:space="preserve"> Et hoc po-
              <lb/>
            teſt intelligi:</s>
            <s xml:id="echoid-s18815" xml:space="preserve"> quoniam ſi aſpexeris aliquid exiſtens in aqua, & tu ſis obliquus à perpendicularibus,
              <lb/>
            exeuntibus à re uiſa ſuper ſuperficiem aquę multa obliquatione, & intuearis illud uerè, deinde mo
              <lb/>
            uearis, & moueas uiſum, donec ponas ipſum in aliqua perpẽdiculari, exeunte à re uiſa ſuper ſuper-
              <lb/>
            ficiem aquæ, & aſpexeris:</s>
            <s xml:id="echoid-s18816" xml:space="preserve"> tunc uidebis illud manifeſtius, quàm cum eras obliquus:</s>
            <s xml:id="echoid-s18817" xml:space="preserve"> & nulla eſt dif-
              <lb/>
            ferentia inter duos ſitus, niſi quia in primo, forma, quæ exit ad uiſum, eſt refracta & multùm obli-
              <lb/>
            qua:</s>
            <s xml:id="echoid-s18818" xml:space="preserve"> in ſecundo autem forma exit rectè, aut quædam pars ipſius exit rectè, & quædam modicũ obli
              <lb/>
            què aut ferè rectè.</s>
            <s xml:id="echoid-s18819" xml:space="preserve"> Ex hac ergo experimentatione declaratur, quòd refractio debilitat formas refra
              <lb/>
            ctas.</s>
            <s xml:id="echoid-s18820" xml:space="preserve"> Item ea, quę ſunt in aqua, & ultra uitrum & conſimilia, quando refringuntur ad uiſum, deferũt
              <lb/>
            ſecum colorem corporis, in quo exiſtunt.</s>
            <s xml:id="echoid-s18821" xml:space="preserve"> In illis ergo, quæ comprehendũtur refractè ultra corpora
              <lb/>
            diaphana, accidunt propter refractionem fallaciæ, quæ non accidunt in eis, quæ uidentur rectè, ſci
              <lb/>
            licet diuerſitas poſitionis & diſtantiæ, & debilitas lucis & coloris.</s>
            <s xml:id="echoid-s18822" xml:space="preserve"> Præterea accidunt eis iſta, quæ
              <lb/>
            accidunt illis, quæ rectè uidentur.</s>
            <s xml:id="echoid-s18823" xml:space="preserve"> Formæ enim eorum, quæ comprehenduntur refractè, compre-
              <lb/>
            henduntur in oppoſitione uiſus & in rectitudine linearũ radialiũ.</s>
            <s xml:id="echoid-s18824" xml:space="preserve"> Quicquid ergo accidit eis, quæ
              <lb/>
            uidentur in rectitudine linearũ radialiũ, accidit iſtis.</s>
            <s xml:id="echoid-s18825" xml:space="preserve"> Et in tertio libro declarauimus oẽs illas falla-
              <lb/>
            </s>
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