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-div1893" type="section" level="0" n="0">
          <p>
            <s xml:id="echoid-s50767" xml:space="preserve">
              <pb o="454" file="0756" n="756" rhead="VITELLONIS OPTICAE"/>
            uidit, cum tranſiret quandá aquã, circa quam groſſus fuit aer, & cũ ſtaret, ſtetit & ille alius, & omnia
              <lb/>
            opera ipſius faciebat:</s>
            <s xml:id="echoid-s50768" xml:space="preserve"> cum autem ad aerẽ ſerenum uenit ille notus meus:</s>
            <s xml:id="echoid-s50769" xml:space="preserve"> tunc ſocius eius diſparuit,
              <lb/>
            quia non fuerat niſi forma ſua.</s>
            <s xml:id="echoid-s50770" xml:space="preserve"> Et ſic uiſui debili error accidit:</s>
            <s xml:id="echoid-s50771" xml:space="preserve"> nec mirum:</s>
            <s xml:id="echoid-s50772" xml:space="preserve"> quia & quandoq;</s>
            <s xml:id="echoid-s50773" xml:space="preserve"> ſanis ui
              <lb/>
            ſibus hoc accidit ab aere ſpiſſo & longè diſtante:</s>
            <s xml:id="echoid-s50774" xml:space="preserve"> ſicut etiam auxilio ſpeculorum (ut in 60 th.</s>
            <s xml:id="echoid-s50775" xml:space="preserve"> 7 hu-
              <lb/>
            ius oſtendimus) poſſet fieri, quòd aliquis imaginem propriam uel aliam non in ſpeculo, ſed extra
              <lb/>
            ſpeculum uideret in aere, in loco imaginis, qui per induſtriam poſſet ad locum certum uariari.</s>
            <s xml:id="echoid-s50776" xml:space="preserve"> In ua
              <lb/>
            pore etiã rorido fit reuerberatio luminis, quando incipit uapor aqueus diſſolui in guttas:</s>
            <s xml:id="echoid-s50777" xml:space="preserve"> quia quę-
              <lb/>
            libet ſuarum partium fit quaſi ſpeculum:</s>
            <s xml:id="echoid-s50778" xml:space="preserve"> & ob hoc lumẽ reflectitur ab ipſo:</s>
            <s xml:id="echoid-s50779" xml:space="preserve"> & iſtud apparet in aqua
              <lb/>
            guttatim ſparſa:</s>
            <s xml:id="echoid-s50780" xml:space="preserve"> quoniam ab illa lumen etiam ad partem oppoſitam reflectitur:</s>
            <s xml:id="echoid-s50781" xml:space="preserve"> quamuis poſt refle-
              <lb/>
            xionem coloretur.</s>
            <s xml:id="echoid-s50782" xml:space="preserve"> Patet ergo propoſitum.</s>
            <s xml:id="echoid-s50783" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div1894" type="section" level="0" n="0">
          <head xml:id="echoid-head1390" xml:space="preserve" style="it">62. A ſuperficie aquæ & aeris denſi, & uaporis roridi, & ſimilibus refractionem fieri ad
            <lb/>
          perpendicularem patens eſt.</head>
          <p>
            <s xml:id="echoid-s50784" xml:space="preserve">Quod hic declarandum proponitur, patet ք 4 huius:</s>
            <s xml:id="echoid-s50785" xml:space="preserve"> ſed etiã experimẽtis cóprobatur:</s>
            <s xml:id="echoid-s50786" xml:space="preserve"> & hoc eſt
              <lb/>
            uniuerſale.</s>
            <s xml:id="echoid-s50787" xml:space="preserve"> Quando forma rei uel radius per mediũ rarius ad dẽſius diaphanum procedit:</s>
            <s xml:id="echoid-s50788" xml:space="preserve"> tũc ſemք
              <lb/>
            in medio ſecũdi diaphani fit refractio ad perpendicularẽ.</s>
            <s xml:id="echoid-s50789" xml:space="preserve"> Verbi gratia, expoſita a qua in uaſe ſoli, in
              <lb/>
            fundo uaſis uidebuntur radij aggregari.</s>
            <s xml:id="echoid-s50790" xml:space="preserve"> Luceſcente etiã ſole ſuper aerẽ denſum uiſui & ſoli interpo
              <lb/>
            ſitũ quãdoq;</s>
            <s xml:id="echoid-s50791" xml:space="preserve"> lux aggregatur, & maior calor peruenit in nobis, quãuis multa pars luminis ſuperius
              <lb/>
            ad nubes uicinas reflectitur:</s>
            <s xml:id="echoid-s50792" xml:space="preserve"> & hoc fit maximè in tẽpore præcedente tẽpus pluuiarũ:</s>
            <s xml:id="echoid-s50793" xml:space="preserve"> unde poſt talẽ
              <lb/>
            improportionatũ tempori calorem & lumen inſolitum ſæpius pluuia deſcendit.</s>
            <s xml:id="echoid-s50794" xml:space="preserve"> Ex quo patet, quia
              <lb/>
            nube in uaporẽ roridũ reſoluta, refractio fit radiorũ in ipſo uapore rorido, & ad nos perueniuntra-
              <lb/>
            dij ſolis aggregati per refractionem.</s>
            <s xml:id="echoid-s50795" xml:space="preserve"> Patet ergo quòd in aqua & aere denſo & uapore rorido, qñ for
              <lb/>
            ma uel lumẽ eſt in rariore diaphano, & incidit illis diaphanis denſiorib.</s>
            <s xml:id="echoid-s50796" xml:space="preserve"> diaphanũ quoq;</s>
            <s xml:id="echoid-s50797" xml:space="preserve">, in quo eſt
              <lb/>
            uiſus, multũ differt à diaphano, à quo fit refractio:</s>
            <s xml:id="echoid-s50798" xml:space="preserve"> tũc fiet refractio ſenſibilis ad perpẽdicularẽ.</s>
            <s xml:id="echoid-s50799" xml:space="preserve"> Q đ
              <lb/>
            ſi forma uel lumen ſit in denſiore diaphano, uel ultra denſius diaphanũ uideatur:</s>
            <s xml:id="echoid-s50800" xml:space="preserve"> tunc fiet refractio
              <lb/>
            à perpendiculari:</s>
            <s xml:id="echoid-s50801" xml:space="preserve"> & ob hoc omnia talia uiſui apparent maiora ſua certa quantitate, ut patet per 42
              <lb/>
            huius.</s>
            <s xml:id="echoid-s50802" xml:space="preserve"> Et ob hoc accidit quòd ſummitates rerum in mari uiſarum refractè uidentur:</s>
            <s xml:id="echoid-s50803" xml:space="preserve"> eò quòd forma
              <lb/>
            ipſarũ diſpergitur à perpendiculari in ſecundo diaphano ſubtiliori, ſcilicet in aere, & uidẽtur formę
              <lb/>
            illorũ in cõcurſu lineę refractionis cũ perpẽdiculari ducta àre uiſa ad ſuperficiẽ aquę, ut patet ք 15
              <lb/>
            th.</s>
            <s xml:id="echoid-s50804" xml:space="preserve"> huius:</s>
            <s xml:id="echoid-s50805" xml:space="preserve"> & denarius uidetur poſitus in uaſe ſub aqua in ea diſtãtia, in qua uiſus propter altitudinẽ
              <lb/>
            peripherię uaſis ſine aqua ipſum denariũ directè non uideret:</s>
            <s xml:id="echoid-s50806" xml:space="preserve"> & tunc uidetur etiã maior, quoniã ſub
              <lb/>
            maiori angulo uidetur.</s>
            <s xml:id="echoid-s50807" xml:space="preserve"> In aere etiã dẽſo, utpote qñ euri flãt, & aer humidus fit & ingroſſatur, omniũ
              <lb/>
            rerũ uidentur magnitudines maiores.</s>
            <s xml:id="echoid-s50808" xml:space="preserve"> Sol quoq;</s>
            <s xml:id="echoid-s50809" xml:space="preserve"> & omnia aſtra orientia & occidentia propter cali-
              <lb/>
            ginẽ & aerẽ uaporib.</s>
            <s xml:id="echoid-s50810" xml:space="preserve"> terræ ingroſſatum illis uiſibus interpoſitum, uidentur maiora, quàm in medio
              <lb/>
            cœli exiſtentia, ut patet per 54 huius:</s>
            <s xml:id="echoid-s50811" xml:space="preserve"> & hęc eſt cauſſa temporalis:</s>
            <s xml:id="echoid-s50812" xml:space="preserve"> alia uerò eſt perpetua, quam dixi-
              <lb/>
            musibidẽ.</s>
            <s xml:id="echoid-s50813" xml:space="preserve"> Ex hoc etiã prouenit quòd ſi in loco imaginis, uel inter imaginẽ & uiſum ponatur uitrũ
              <lb/>
            clarũ uel cryſtallus, ita utimago reflexa à ſpeculo ad certũ locum aeris uideatur per uitrũ:</s>
            <s xml:id="echoid-s50814" xml:space="preserve"> tũc enim
              <lb/>
            imago maior uidebitur, & ſecundũ qđ media diaphana multiplicata à dẽſiore in rarius fuerint, for
              <lb/>
            ma ſe uiſibus ita uicináte, qđ ultimò ipſa ք aerẽ uideatur:</s>
            <s xml:id="echoid-s50815" xml:space="preserve"> tunc forma maxima uidebitur:</s>
            <s xml:id="echoid-s50816" xml:space="preserve"> cuius ratio
              <lb/>
            patet ex præmiſsis pluribus theorematib.</s>
            <s xml:id="echoid-s50817" xml:space="preserve"> huius libri.</s>
            <s xml:id="echoid-s50818" xml:space="preserve"> In iſtis ergo corporib.</s>
            <s xml:id="echoid-s50819" xml:space="preserve"> medijs omnib.</s>
            <s xml:id="echoid-s50820" xml:space="preserve"> ſic diſpo
              <lb/>
            ſitis fit refractio à perpendiculari, ducta à cẽtro rei uiſæ ad ſuperficiẽ corporis diaphani rẽipſam uel
              <lb/>
            formã refractã continẽtis.</s>
            <s xml:id="echoid-s50821" xml:space="preserve"> His ergo modis fit in propoſitis corporib.</s>
            <s xml:id="echoid-s50822" xml:space="preserve"> uel ſimilib.</s>
            <s xml:id="echoid-s50823" xml:space="preserve"> ſibi ad uiſum refra-
              <lb/>
            ctio:</s>
            <s xml:id="echoid-s50824" xml:space="preserve"> inter hęc uerò maximè fit in aqua:</s>
            <s xml:id="echoid-s50825" xml:space="preserve"> magis aũt fit in uapore rorido incipiẽte aqua fieri, ꝗ̃ fiat ab ae
              <lb/>
            re:</s>
            <s xml:id="echoid-s50826" xml:space="preserve"> nec mirum:</s>
            <s xml:id="echoid-s50827" xml:space="preserve"> quia uapor roridus (qui fit tẽpore trãſmutationis nubiũ ex uapore cõtinuo in gutta
              <lb/>
            tim ſparſam aquã) eſt groſsior aere:</s>
            <s xml:id="echoid-s50828" xml:space="preserve"> unde in ipſa facta refractio plus ſentitur.</s>
            <s xml:id="echoid-s50829" xml:space="preserve"> Non poteſt aũt tunc fi-
              <lb/>
            gura rei uiſæ, cuius forma refringitur, diſtin ctè ad uiſum peruenire, propter refractionũ multitudi-
              <lb/>
            nẽ:</s>
            <s xml:id="echoid-s50830" xml:space="preserve"> ſed peruenit uiſui tantũ aliqua forma rei:</s>
            <s xml:id="echoid-s50831" xml:space="preserve"> ſicut patet etiã quòd in ſpeculis paruarũ partiũ uel ſu-
              <lb/>
            perficierum fractarũ alterius ſuper alterã eleuatarum, & ſi modicę pręeminentię ſint, ita tamẽ quòd
              <lb/>
            ſuperficies ipſorum ſpeculorum non ſint in eadem linea recta uel curua:</s>
            <s xml:id="echoid-s50832" xml:space="preserve"> tunc non apparet rei pro-
              <lb/>
            pria quantitas uel figura, ſed apparet tantũ color ipſius rei uiſæ, cuius forma reflectitur ab ipſis.</s>
            <s xml:id="echoid-s50833" xml:space="preserve"> Per
              <lb/>
            quod manifeſtè patet quòd forma corporis luminoſi, quæ ab aqua uel aere groſſo integrè, ſcilicet
              <lb/>
            quo ad figuram & lucem uel colorem reflectitur ad uiſum, à uapore rorido reflectitur, ſine figura &
              <lb/>
            quantitate certa, ſed tantũ cum ſuo colore uel lumine.</s>
            <s xml:id="echoid-s50834" xml:space="preserve"> Et ita, cum à uapore rorido fit reflexio ad ui-
              <lb/>
            ſum luminis ſolaris uel ſtellarum, non uidentur formarum reflexarum figuræ propriæ, ſed tantùm
              <lb/>
            ſormæ luminis reflexi.</s>
            <s xml:id="echoid-s50835" xml:space="preserve"> Patet ergo propoſitum</s>
          </p>
        </div>
        <div xml:id="echoid-div1895" type="section" level="0" n="0">
          <head xml:id="echoid-head1391" xml:space="preserve" style="it">63. Omnis corporis ſphærici luminoſi irradiationem in corpore, (cuius ſuperficies æquidiſtat
            <lb/>
          ſuperficiei contingenti corpus luminoſum ſphæricum in puncto, ubi perpendicular is ducta à cen
            <lb/>
          tro corporis ſphærici ſuper ſuperficiem corporis illumin andi ſecat ſuperficiem corporis ſphærici)
            <lb/>
          poßibile eſt fieri ſecundum pyramidem rotundam, cuius baſis eſt in corpore irradiato, uertex ue
            <lb/>
          rò in centro corporis luminoſi. Ex quo patet omnem huiuſmodi irradiationem fieri ſecundũ an-
            <lb/>
          gulos incidentiæ æquales.</head>
          <p>
            <s xml:id="echoid-s50836" xml:space="preserve">Sit corpus luminoſum ſphæricum, in quo ſit circulus magnus, qui b c d:</s>
            <s xml:id="echoid-s50837" xml:space="preserve"> & eius centrũ ſit pun-
              <lb/>
            </s>
          </p>
        </div>
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    </echo>
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