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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      <text xml:lang="lat" type="free">
        <div xml:id="echoid-div1883" type="section" level="0" n="0">
          <p>
            <s xml:id="echoid-s50453" xml:space="preserve">
              <pb o="449" file="0751" n="751" rhead="LIBER DECIMVS."/>
            ſtellis interuen erit:</s>
            <s xml:id="echoid-s50454" xml:space="preserve"> tũc extenditur forma ſtellę ad ſuperficiem uaporis ſupremã, & refringitur in il-
              <lb/>
            la ad perpẽdicularem:</s>
            <s xml:id="echoid-s50455" xml:space="preserve"> deinde extẽditur ad ſuperficiẽ infimã uaporis, & refringitur ab illa ad aerem
              <lb/>
            purũ continentẽ uiſum:</s>
            <s xml:id="echoid-s50456" xml:space="preserve"> & ſit illa refractio ad partẽ contrariam perpẽdicularis, exeuntis à pũcto re-
              <lb/>
            fractionis ſuper planam ſuperficiem uaporis.</s>
            <s xml:id="echoid-s50457" xml:space="preserve"> Sic ergo forma ſtellæ & earũ diſtantia uidetur maior,
              <lb/>
            quàm ſi uideretur poſt refractionem factam in concauo c œli à ſupremo corporis elementaris, nul-
              <lb/>
            la facta refractione in ſuperficie uaporis ad aerem, qui eſt ſub uapore, ut ſub dẽſiore corpore rarior
              <lb/>
            conſiſtens & continens ipſum uiſum.</s>
            <s xml:id="echoid-s50458" xml:space="preserve"> Cauſſa uero, propter quam omniuapore medio excluſo, ui-
              <lb/>
            dẽtur ſtellę & ſtellarũ diſtantiæ maiores in horizonte ꝗ̃ in medio c œli aut prope, coadiuuatur plu-
              <lb/>
            rimũ per exiſtimationẽ uidentis:</s>
            <s xml:id="echoid-s50459" xml:space="preserve"> quoniã exiſtimat ſtellas plus diſtare à uiſu in horizõte ꝗ̃ in medio
              <lb/>
            cœli:</s>
            <s xml:id="echoid-s50460" xml:space="preserve"> exiſtimãs ipſam partẽ cœli, quę eſt iuxta zenith capitis propinquiorẽ ſibi, ꝗ̃ eã, quæ eſt in hori-
              <lb/>
            zonte, ut oſten dimus per 13 th.</s>
            <s xml:id="echoid-s50461" xml:space="preserve"> 4 huius.</s>
            <s xml:id="echoid-s50462" xml:space="preserve"> Comprehendit ergo uiſus quantitatem ſtellę, & quantitatẽ
              <lb/>
            diſtantię, quę eſt inter ſtellas, cum fuerint in horizonte aut prope, ex comparatione anguli, ſub quo
              <lb/>
            fit uiſio, ad diſtantiam remotam:</s>
            <s xml:id="echoid-s50463" xml:space="preserve"> & cũ fuerint in medio cœli aut prope illud, comprehendit ipſarũ
              <lb/>
            quantitatem ex comparatione anguli æqualis primo aut ferè, ad diſtãtiam propinquam, inter quã
              <lb/>
            & diſtantiam horizontis uidetur diuerſitas maxima.</s>
            <s xml:id="echoid-s50464" xml:space="preserve"> Et ſic iudicat ſtellarum quantitatem ſecundũ
              <lb/>
            modũ, quo dijudicat quantitatem uiſibilium conſuetorũ.</s>
            <s xml:id="echoid-s50465" xml:space="preserve"> Quæ enim à rem otiori ſub eodẽ angulo
              <lb/>
            uidentur, quo alia propin quiora:</s>
            <s xml:id="echoid-s50466" xml:space="preserve"> illa remotiora iudicãtur à uidentibus eſſe maiora, ut oſtendimus
              <lb/>
            hoc 4 libro huius.</s>
            <s xml:id="echoid-s50467" xml:space="preserve"> Hęc enim cauſſa uiſionis ſtellarum eſt perpetua & immutabilis, omnibus uidẽti-
              <lb/>
            bus cõmunis.</s>
            <s xml:id="echoid-s50468" xml:space="preserve"> Et eodẽ modo accidit uidentibus in cõprehenſione diſtantiarũ ipſarũ ſtellarũ:</s>
            <s xml:id="echoid-s50469" xml:space="preserve"> nam
              <lb/>
            formæ harum diſtantiarum non diuerſantur apud uiſum in diuerſis temporibus, ſed ſunt ſemper
              <lb/>
            eodem modo ſe habentes, & uiſus aſsimilat ipſas diſtantijs rerum aſſuetarum, quæ maximæ diſtant
              <lb/>
            à uiſu ſuper ſuperficiem terræ ipſius.</s>
            <s xml:id="echoid-s50470" xml:space="preserve"> Patet ergo propoſitum.</s>
            <s xml:id="echoid-s50471" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div1884" type="section" level="0" n="0">
          <head xml:id="echoid-head1383" xml:space="preserve" style="it">55. Scintillatio accidit ſemper omnibus ſtellis fixis propter diuaricationẽ formæ in loco ima-
            <lb/>
          ginis ex motu ſubiecti corporis accidentem.</head>
          <p>
            <s xml:id="echoid-s50472" xml:space="preserve">Quoniam enim, ut patet ex præmiſsis quinq;</s>
            <s xml:id="echoid-s50473" xml:space="preserve"> theorematibus, locus imaginis formæ cuiuslibet
              <lb/>
            ſtellarum eritin conuexo aeris uel ignis ſub concauo cœli infimi ignem continentis:</s>
            <s xml:id="echoid-s50474" xml:space="preserve"> horũ aũt ele-
              <lb/>
            mentorũ quodlibet mobile eſt per ſemotu recto, utpote ſurſum propter leuitatẽ, quę eſt in illis:</s>
            <s xml:id="echoid-s50475" xml:space="preserve"> mo
              <lb/>
            uetur aũt per accidens motu circulari unà cũ motu diurno cœli, propter quod formã ſtellarũ ipſis
              <lb/>
            incidentẽ neceſſe eſt diuaricari & diſtrahi, ſicut & ipſa forma uidetur aliqualiter locũ mutare pro-
              <lb/>
            pter motum corporis, in quo uidetur:</s>
            <s xml:id="echoid-s50476" xml:space="preserve"> nec eſt diuerſitas in iſto, ſiue lumen ſtellarũ per ſe ipſum dif-
              <lb/>
            fundatur, ſiue fiat hoc propter reflexionẽ luminis ſolaris à ſtellis.</s>
            <s xml:id="echoid-s50477" xml:space="preserve"> Semper enim tã lumen per ſe dif-
              <lb/>
            fuſum à corpore luminoſo, quàm lumen ab alijs corporibus diffuſum (quando per refractionẽ ui-
              <lb/>
            detur) fit debilius per 10 huius.</s>
            <s xml:id="echoid-s50478" xml:space="preserve"> Vnde cum habet locum imaginis in corpore mobili diuerſis moti-
              <lb/>
            bus, aut uno motu forti:</s>
            <s xml:id="echoid-s50479" xml:space="preserve"> neceſſe eſt formam illã debilitatã diuaricatã & diſtractã uideri, propter mo
              <lb/>
            tũ corporis ſubiecti, in quo uidetur:</s>
            <s xml:id="echoid-s50480" xml:space="preserve"> unde in his talis reflexio luminis nõ eſt cauſſa.</s>
            <s xml:id="echoid-s50481" xml:space="preserve"> Et huius ſimile
              <lb/>
            eſt in aqua uelociter currente, à cuius ſuperficie formæ ſtellarum reflexæ uidentur plus ſcintillare
              <lb/>
            quàm in ipſo loco ſuæ imaginis refractè per aerẽ uideantur:</s>
            <s xml:id="echoid-s50482" xml:space="preserve"> quoniã propter motũ aqę diſtrahitur
              <lb/>
            forma reflexa, & mutatur locus imaginis reflexę:</s>
            <s xml:id="echoid-s50483" xml:space="preserve"> propter quod & ſtellarũ formę plus moueriuiden
              <lb/>
            tur:</s>
            <s xml:id="echoid-s50484" xml:space="preserve"> & ideo apparent amplius ſcintillantes.</s>
            <s xml:id="echoid-s50485" xml:space="preserve"> Similiter quoq;</s>
            <s xml:id="echoid-s50486" xml:space="preserve"> formę ſtellarũ in loco ſuę imaginis tẽpo
              <lb/>
            re uentorũ propter maiorẽ motũ corporis medij plus ſcintillãt.</s>
            <s xml:id="echoid-s50487" xml:space="preserve"> In planetis uerò nõ ſemper accidit
              <lb/>
            ſcintillatio:</s>
            <s xml:id="echoid-s50488" xml:space="preserve"> quoniã licet plus ſcintillẽt, & in eis ſit idẽ locus imaginis, & ipſorũ formæ propter refra
              <lb/>
            ctionẽ debilitẽtur:</s>
            <s xml:id="echoid-s50489" xml:space="preserve"> tamẽ propter ipſorũ ꝓpinquitatẽ ad nos uidẽtes nõ accidit eis multa debilitas:</s>
            <s xml:id="echoid-s50490" xml:space="preserve">
              <lb/>
            quia minor fit in eis refractio per 14 th.</s>
            <s xml:id="echoid-s50491" xml:space="preserve"> huius.</s>
            <s xml:id="echoid-s50492" xml:space="preserve"> Perueniũt ergo formę ipſorũ fortes ad uiſum:</s>
            <s xml:id="echoid-s50493" xml:space="preserve"> unde
              <lb/>
            & locũ imaginis ſuæ (quãuis corpus ſubiectũ moueatur) penetrãt immotè & ſine omni diuarica-
              <lb/>
            tione:</s>
            <s xml:id="echoid-s50494" xml:space="preserve"> niſi fortè aliquod corpus groſsius aere uiſibus & planetarũ formis interponatur:</s>
            <s xml:id="echoid-s50495" xml:space="preserve"> utpote ua-
              <lb/>
            por a quaticus groſſus:</s>
            <s xml:id="echoid-s50496" xml:space="preserve"> tũc etenim {por}pter incertitudinẽ motus illius uaporis (pręſertim cũ à uentis
              <lb/>
            agitatur) formę planetarũ quaſi ſcintillãtes քueniũt ad uiſum.</s>
            <s xml:id="echoid-s50497" xml:space="preserve"> Et ex hac cauſſa aliquãdo & ipſum
              <lb/>
            ſolẽ uidemus ſcintillãtẽ in mane, cũ fuerit in ortu ſuo uiſibilis ſecũdũ ſpirituũ uiſibiliũ reſolutionẽ,
              <lb/>
            propter quorũ reſolutionẽ & motũ, ſol ſemper aliquãdiu aſpectus uidetur ſcintillare & moueri for
              <lb/>
            ma eius:</s>
            <s xml:id="echoid-s50498" xml:space="preserve"> quoniã recipitur in ſpiritib.</s>
            <s xml:id="echoid-s50499" xml:space="preserve"> motis, qui propter uictoriã luminis cũ fuerint in fine ſuę cor-
              <lb/>
            ruptionis ab actu uiſiõis, rarificãtur ſuper ſuę naturę cõſiſtẽtiã:</s>
            <s xml:id="echoid-s50500" xml:space="preserve"> unde mouẽtur motu ſibi impro por
              <lb/>
            tio nato & inſolito, fiuntq́;</s>
            <s xml:id="echoid-s50501" xml:space="preserve"> cauſſa motus formę uiſę:</s>
            <s xml:id="echoid-s50502" xml:space="preserve"> & tũc uidetur forma rei uiſæ ſcintillare:</s>
            <s xml:id="echoid-s50503" xml:space="preserve"> ſicut e-
              <lb/>
            tiã accidit cũ à corporibus politis fit fortis reflexio luminis ad uiſum:</s>
            <s xml:id="echoid-s50504" xml:space="preserve"> tũc enim ꝓpter improportio
              <lb/>
            nẽ illius luminis ad ſpiritus uiſibiles fit motus illorũ ſpirituũ, & uidẽtur formę illorũ corporũ ſcin-
              <lb/>
            tillãtes & motę, ꝗ a recipiũtur in corpore cõmoto.</s>
            <s xml:id="echoid-s50505" xml:space="preserve"> Sic itaq;</s>
            <s xml:id="echoid-s50506" xml:space="preserve"> ſcintillatio ſemper accidit omnib.</s>
            <s xml:id="echoid-s50507" xml:space="preserve"> ſtellis
              <lb/>
            fixis:</s>
            <s xml:id="echoid-s50508" xml:space="preserve"> quoniã cauſſa illius eſt քpetua, ſcilicet diuaricatio formę ſuę in loco imaginis, accidẽs ex mo-
              <lb/>
            tu ſubiecti corporis.</s>
            <s xml:id="echoid-s50509" xml:space="preserve"> In planetis uerò ſcintillatio accidit ut rarò:</s>
            <s xml:id="echoid-s50510" xml:space="preserve"> ꝗa cauſſa eius eſt eueniẽs ut rarò.</s>
            <s xml:id="echoid-s50511" xml:space="preserve"> In
              <lb/>
            alijs uerò corporũ formis, quarũ excellẽtia corrũpit ſenſum, nõ eſt propriè ſcintillatio, ſiue illa cor-
              <lb/>
            ruptio fiat per ſimplicẽ luminis immiſsionẽ, uel per reflexionẽ à corporibus politis:</s>
            <s xml:id="echoid-s50512" xml:space="preserve"> quia illa ſcintil
              <lb/>
            latio nõ accidit ſenſui, ut eſt ſuæ ꝓpriæ diſpoſitionis, ſed ut eſt in fine ſuę corruptionis.</s>
            <s xml:id="echoid-s50513" xml:space="preserve"> Etenim ſi ha
              <lb/>
            bẽtibus in oculis formã rei motæ, aut etiã mouẽtibus, omnia moueri uideantur ꝓpter motũ ſpiri-
              <lb/>
            tuũ ſine regimine animæ diſcurrentiũ:</s>
            <s xml:id="echoid-s50514" xml:space="preserve"> nõ propter hoc dicũtur formę rerũ omniũ ſcintillare.</s>
            <s xml:id="echoid-s50515" xml:space="preserve"> Patet
              <lb/>
            ergo ꝓpoſitũ.</s>
            <s xml:id="echoid-s50516" xml:space="preserve"> Et quia ſecũdũ pręmiſſos refractionũ modos paſsiones uiſibiliũ infimorũ & ſupre-
              <lb/>
            </s>
          </p>
        </div>
      </text>
    </echo>
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