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

List of thumbnails

< >
261
261 (255) 		262
262 (256)
263
263 (257) 		264
264 (258)
265
265 (259) 		266
266 (260)
267
267 (261) 		268
268 (262)
269
269 (263) 		270
270 (264)
< >
page |< < (251) of 778 > >|
    <echo version="1.0RC">
      <text xml:lang="lat" type="free">
        <div xml:id="echoid-div571" type="section" level="0" n="0">
          <p>
            <s xml:id="echoid-s17537" xml:space="preserve">
              <pb o="251" file="0257" n="257" rhead="OPTICAE LIBER VII."/>
            hendit extremitatem ſtili in aqua ab iſto loco, ſcilicet quia comprehendit extremitatem ſtili, quan-
              <lb/>
            do fuit inter caſum perpendicularis & extremitatem diametri circuli medij, quæ tranſit per cen-
              <lb/>
            tra duorum foraminum.</s>
            <s xml:id="echoid-s17538" xml:space="preserve"> Et illa forma etiam exiuit ab aqua, & refracta eſt in aere:</s>
            <s xml:id="echoid-s17539" xml:space="preserve"> & aer eſt ſubti-
              <lb/>
            lior aqua.</s>
            <s xml:id="echoid-s17540" xml:space="preserve"> Deinde oportet experimentatorem euellere uitrum, & ponere ipſum ſupra laminam
              <lb/>
            extra huiuſmodi ſitum, ſcilicet, ut ponat conuexum eius ex parte duorum foraminum, & ponat
              <lb/>
            differentiam eius communem ſuper lineam æqualem in ſuperficie laminæ, in qua poſuerat illam
              <lb/>
            in prædicto ſitu, & ponat medium differentiæ communis ſuper centrum laminæ:</s>
            <s xml:id="echoid-s17541" xml:space="preserve"> & ſic linea, quæ
              <lb/>
            tranſit per centra duorum foraminum, erit obliqua ſuper ſuperficiem uitri æqualem, & perpendi-
              <lb/>
            cularis ſuper ſuperficiem eius conuexam:</s>
            <s xml:id="echoid-s17542" xml:space="preserve"> & applicet uitrum in hoc ſitu, & ponat inſtrumentum
              <lb/>
            in uas, & ponat extremitatem ſtili ſuper extremitatem diametri circuli medij, ut prius fecerat, &
              <lb/>
            ponat uiſum ſuum ſuper ſuperius foramen, & intueatur oram inſtrumenti:</s>
            <s xml:id="echoid-s17543" xml:space="preserve"> non enim uidebit tunc
              <lb/>
            extremitatem ſtili:</s>
            <s xml:id="echoid-s17544" xml:space="preserve"> deinde moueat ſtilum ad partem caſus perpendicularis:</s>
            <s xml:id="echoid-s17545" xml:space="preserve"> & tunc non uidebit ex-
              <lb/>
            tremitatem ſtili:</s>
            <s xml:id="echoid-s17546" xml:space="preserve"> deinde moueat eundem ad partem contrariam illi, in qua eſt caſus perpendicula-
              <lb/>
            ris per circumferentiam medij circuli, & ſuauiter:</s>
            <s xml:id="echoid-s17547" xml:space="preserve"> tunc enim uidebit extremitatem ſtili.</s>
            <s xml:id="echoid-s17548" xml:space="preserve"> Sic ergo li-
              <lb/>
            nea recta, quæ exit ab extremitate ſtili ad centrum uitri, cum fuerit extenſa rectè in corpore uitri,
              <lb/>
            & extenſa fuerit cum ipſa perpendicularis exiens à centro uitri:</s>
            <s xml:id="echoid-s17549" xml:space="preserve"> erit linea, quæ tranſit per centra
              <lb/>
            duorum foraminum, media inter duas lineas.</s>
            <s xml:id="echoid-s17550" xml:space="preserve"> Et forma extremitatis ſtili, quæ extenditur ſuper
              <lb/>
            hanclineam, cum fuerit extenſa ad centrum uitri:</s>
            <s xml:id="echoid-s17551" xml:space="preserve"> refringetur ſuper lineam, quæ tranſit per centra
              <lb/>
            duorum foraminum.</s>
            <s xml:id="echoid-s17552" xml:space="preserve"> Erit ergo refractio iſta ad partem perpendicularis exeuntis à loco refractio-
              <lb/>
            nis ſuper ſuperficiem uitri.</s>
            <s xml:id="echoid-s17553" xml:space="preserve"> Et hæc forma exit ab aere, & refringitur in uitro:</s>
            <s xml:id="echoid-s17554" xml:space="preserve"> & uitrum eſt groſsius
              <lb/>
            aere.</s>
            <s xml:id="echoid-s17555" xml:space="preserve"> Ex omnibus ergo iſtis experimentationibus patet, quòd uiſus comprehendit uiſibilia, quæ
              <lb/>
            ſunt in aqua, & ultra corpora diaphana, quæ differunt à diaphanitate aeris, ſecundum refractio-
              <lb/>
            nem, præterquam illa, quæ ſunt ſuper lineas perpendiculares ſuper ſuperficiem corporis diapha-
              <lb/>
            ni, in quo exiſtit:</s>
            <s xml:id="echoid-s17556" xml:space="preserve"> & quòd refractio formarum ipſorum eſt in ſuperficiebus perpendicularibus ſu-
              <lb/>
            per ſuperficies corporum diaphanorum.</s>
            <s xml:id="echoid-s17557" xml:space="preserve"> Omne enim quod experimentatum eſt per prædictum in-
              <lb/>
            ſtrumentum, inuenitur refringi in ſuperficie medij circuli, de quo patuit, [5 n] quòd eſt perpendi-
              <lb/>
            cularis ſuper ſuperficies corporum diaphanorum, & ſuper ſuperficies corporum contingentium
              <lb/>
            ſuperficies eorum.</s>
            <s xml:id="echoid-s17558" xml:space="preserve"> Ex hac ergo experimentatione declarabitur etiam, quòd formæ, quæ compre-
              <lb/>
            henduntur à uiſu ſecundum refractionem, quæ exeunt à groſsiore corpore diaphano ad ſubtilius,
              <lb/>
            refringuntur ad partem contrariam illi, in qua eſt perpendicularis exiens à loco refractionis ſuper
              <lb/>
            ſuperficiem corporis diaphani:</s>
            <s xml:id="echoid-s17559" xml:space="preserve"> & quæ exeunt à ſubtiliore ad groſsius, refringuntur ad partem, in
              <lb/>
            qua eſt perpendicularis prædicta.</s>
            <s xml:id="echoid-s17560" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div573" type="section" level="0" n="0">
          <head xml:id="echoid-head497" xml:space="preserve" style="it">15. Stella uidetur refractè. 49 p 10.</head>
          <p>
            <s xml:id="echoid-s17561" xml:space="preserve">STellæ autem comprehenduntur etiam ſecundum refractionem:</s>
            <s xml:id="echoid-s17562" xml:space="preserve"> nam corpus cœli eſt ſubtilius
              <lb/>
            corpore aeris, id eſt maioris diaphanitatis.</s>
            <s xml:id="echoid-s17563" xml:space="preserve"> Hoc autem poteſt experimentari experimentatio-
              <lb/>
            ne, quæ oſtendet, quòd ſtellæ comprehendantur ſecundum refractionem:</s>
            <s xml:id="echoid-s17564" xml:space="preserve"> ex quo patebit e-
              <lb/>
            tiam, quòd corpus cœli eſt magis diaphanum corpore aeris.</s>
            <s xml:id="echoid-s17565" xml:space="preserve"> Et cum quis hoc uoluerit experiri, ac-
              <lb/>
            cipiat inſtrumentum de armillis, & ponat illud in loco eminente, in quo poterit apparere hori-
              <lb/>
            zon orientalis, & ponat inſtrumentum armillarum ſuo modo proprio:</s>
            <s xml:id="echoid-s17566" xml:space="preserve"> ſcilicet ut ponat armillam,
              <lb/>
            quæ eſt in loco circuli meridionalis, in ſuperficie circuli meridiei, & polus eius ſit exaltatus à terra
              <lb/>
            ſecundum altitudinem poli mundi ſupra horizontem loci, in quo ponitur inſtrumentum:</s>
            <s xml:id="echoid-s17567" xml:space="preserve"> & in no-
              <lb/>
            cte obſeruet aliquam ſtellarum fixarum magnarum, quæ tranſit per uerticem capitis illius loci, aut
              <lb/>
            prope, & obſeruet illam ab ortu ſuo in oriente:</s>
            <s xml:id="echoid-s17568" xml:space="preserve"> ſtella autem orta, reuoluat armillam, quæ reuo lui-
              <lb/>
            tur in circuitu poli æquinoctialis, donec fiat æquidiſtans ſtellæ, & certificetur locus ſtellæ exar-
              <lb/>
            milla:</s>
            <s xml:id="echoid-s17569" xml:space="preserve"> & ſic habebit longitudinem ſtellæ à polo mundi.</s>
            <s xml:id="echoid-s17570" xml:space="preserve"> Deinde obſeruet ſtellam, quouſque per-
              <lb/>
            uenerit ad circulum meridiei, & reuoluat armillam, quam prius mouerat, donec fiat æquidiſtans
              <lb/>
            ſtellæ:</s>
            <s xml:id="echoid-s17571" xml:space="preserve"> & ſic habebit longitudinem ſtellæ à polo mundi, cum ſtella fuerit in uertice capitis.</s>
            <s xml:id="echoid-s17572" xml:space="preserve"> Hoc au-
              <lb/>
            tem facto, inueniet remotionem ſtellæ à polo mundi in aſcenſione, minorem remotione eius à po-
              <lb/>
            lo mundi in hora exiſtentiæ eius in uertice capitis.</s>
            <s xml:id="echoid-s17573" xml:space="preserve"> Ex quo patet, quòd uiſus comprehendit ſtellas
              <lb/>
            refractè, non rectè:</s>
            <s xml:id="echoid-s17574" xml:space="preserve"> Stella enim fixa ſemper mouetur per eundẽ circulũ de circulis æquidiſtantibus
              <lb/>
            æquatori, & nunquam exit ab ipſo, ita ut appareat, niſi in longiſsimo tempore.</s>
            <s xml:id="echoid-s17575" xml:space="preserve"> Et ſi ſtella compre-
              <lb/>
            henderetur rectè:</s>
            <s xml:id="echoid-s17576" xml:space="preserve"> tunc lineæ radiales extenderentur à uiſu rectè ad ſtellas, & extenderentur for-
              <lb/>
            mæ ſtellarum per lineas radiales rectè, quouſque peruenirent ad uiſum.</s>
            <s xml:id="echoid-s17577" xml:space="preserve"> Et ſi forma extendere-
              <lb/>
            tur à ſtella recte ad uiſum:</s>
            <s xml:id="echoid-s17578" xml:space="preserve"> tunc uiſus comprehenderet eam in ſuo loco:</s>
            <s xml:id="echoid-s17579" xml:space="preserve"> & ſic inueniret diſtantiam
              <lb/>
            ſtellæ fixæ à polo mundi in eadem nocte eandem:</s>
            <s xml:id="echoid-s17580" xml:space="preserve"> Sed diſtantia ſtellæ mutatur eadem nocte à po-
              <lb/>
            lo mundi:</s>
            <s xml:id="echoid-s17581" xml:space="preserve"> ergo uiſus non rectè comprehendit ſtellam.</s>
            <s xml:id="echoid-s17582" xml:space="preserve"> In cœlo autem non eſt corpus denſum ter-
              <lb/>
            ſum, nec in aere, à quo poſsint formæ reflecti.</s>
            <s xml:id="echoid-s17583" xml:space="preserve"> Et cum uiſus non comprehendat ſtellam rectè,
              <lb/>
            nec ſecundum reflexionem:</s>
            <s xml:id="echoid-s17584" xml:space="preserve"> ergo ſecundum refractionem, cùm his ſolis tribus modis compre-
              <lb/>
            hendantur res à uiſu [per 1 n 4.</s>
            <s xml:id="echoid-s17585" xml:space="preserve"> 1 n.</s>
            <s xml:id="echoid-s17586" xml:space="preserve">] Ex diuerſitate ergo diſtantiæ eiuſdem ſtellæ in eadem no-
              <lb/>
            cte à polo mundi, patet procul dubio, quòd uiſus comprehendat ſtellas refractè:</s>
            <s xml:id="echoid-s17587" xml:space="preserve"> Ergo corpus,
              <lb/>
            in quo ſunt ſtellæ fixæ, differt in diaphanitate ab aere.</s>
            <s xml:id="echoid-s17588" xml:space="preserve"> Præterea poteſt experimentari diapha-
              <lb/>
            nitas corporis cœli per experimentationem lunæ.</s>
            <s xml:id="echoid-s17589" xml:space="preserve"> Nam cum æquaueris locum lunæ in aliqua ho-
              <lb/>
            ra prope ortum eius, & pòſt in nocte nota, & in loco noto uerificaueris locum eius à polo mundi,
              <lb/>
            </s>
          </p>
        </div>
      </text>
    </echo>
Impressum