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-s50714" xml:space="preserve">
              <pb o="453" file="0755" n="755" rhead="LIBER DECIMVS."/>
            pyramidis umbrę, (quia ſemper eſt in nadir ſolis) ſecũdũ motũ ſolís declinat:</s>
            <s xml:id="echoid-s50715" xml:space="preserve"> patet qđ primũ, in qđ
              <lb/>
            radius ſolis cadit extra pyramidẽ, eſt ſummitas
              <lb/>
            uaporũ eleuatorũ à terra & aqua.</s>
            <s xml:id="echoid-s50716" xml:space="preserve"> Producatur
              <lb/>
            ergo linea k r q à cẽtro terræ ad ſummitatẽ ua-
              <lb/>
              <figure xlink:label="fig-0755-01" xlink:href="fig-0755-01a" number="885">
                <variables xml:id="echoid-variables862" xml:space="preserve">n a p e q o d r k h f g b r c m</variables>
              </figure>
            porum, ſigneturq́;</s>
            <s xml:id="echoid-s50717" xml:space="preserve"> punctus r in ſuperficie terrę:</s>
            <s xml:id="echoid-s50718" xml:space="preserve">
              <lb/>
            & ducantur lineę k f, k h.</s>
            <s xml:id="echoid-s50719" xml:space="preserve"> Eritq́;</s>
            <s xml:id="echoid-s50720" xml:space="preserve"> arcus f g h pars
              <lb/>
            terræ illuminata:</s>
            <s xml:id="echoid-s50721" xml:space="preserve"> cuius quantitas (ut patet per
              <lb/>
            præmiſſam) eſt 180 partium, 27 minutorum &
              <lb/>
            52 ſecundorum, ſecũdum quod totus circulus
              <lb/>
            e f g h eſt 360 partes:</s>
            <s xml:id="echoid-s50722" xml:space="preserve"> eritq́ue medietas ipſius,
              <lb/>
            quæ eſt f g, partes 90, & 13 minuta, & 56 ſecun-
              <lb/>
            da.</s>
            <s xml:id="echoid-s50723" xml:space="preserve"> Hæc eſt ergo quantitas anguli f k g, ſecundũ
              <lb/>
            quod 4 recti ſunt 360 partes:</s>
            <s xml:id="echoid-s50724" xml:space="preserve"> ſed angulus b k c
              <lb/>
            ex præmiſsis & per 33 p 6 eſt 19 partes:</s>
            <s xml:id="echoid-s50725" xml:space="preserve"> quoniã
              <lb/>
            eſt angulus crepuſcularis:</s>
            <s xml:id="echoid-s50726" xml:space="preserve"> remanet ergo angu-
              <lb/>
            lus h k b 71 partes, 13 minuta, & 56 ſecunda:</s>
            <s xml:id="echoid-s50727" xml:space="preserve"> ſed
              <lb/>
            angulus e k b eſt 90 partes, quoniam eſt rectus:</s>
            <s xml:id="echoid-s50728" xml:space="preserve">
              <lb/>
            remanet ergo angulus e k h 18 partes, 46 minu
              <lb/>
            ta, 4 ſecunda.</s>
            <s xml:id="echoid-s50729" xml:space="preserve"> Et quoniá linea q e eſt æqualis li-
              <lb/>
            neæ q h per 58 th.</s>
            <s xml:id="echoid-s50730" xml:space="preserve"> 1 huius (quoniam ab uno pun
              <lb/>
            cto ducuntur eundem circulum contingẽtes)
              <lb/>
            erit per 8 p 1 angulus q k e ęqualis angulo q k h:</s>
            <s xml:id="echoid-s50731" xml:space="preserve">
              <lb/>
            erit ergo angulus q k e 9 partes, 23 minuta, & 2
              <lb/>
            ſecunda.</s>
            <s xml:id="echoid-s50732" xml:space="preserve"> Et quoniam angulus q e k eſt rectus ք
              <lb/>
            18 p 3:</s>
            <s xml:id="echoid-s50733" xml:space="preserve"> erit angulus k q e per 32 p 1 cóplementum
              <lb/>
            unius recti, hoc eſt 80 partes, 36 minuta, & 58 ſe
              <lb/>
            cunda, prout 4 recti ualent 360 partes:</s>
            <s xml:id="echoid-s50734" xml:space="preserve"> & ſecun
              <lb/>
            dũ quod duo recti ualent 360 partes, erit angu-
              <lb/>
            lus k q e 161 partes, 13 minuta, & 56 ſecunda.</s>
            <s xml:id="echoid-s50735" xml:space="preserve"> Cir
              <lb/>
            cumſcripto ergo circulo ipſi trigono q e k:</s>
            <s xml:id="echoid-s50736" xml:space="preserve"> erit
              <lb/>
            arcus, quem ſubtendit linea k e 161 partes, 13 mi
              <lb/>
            nuta, & 56 ſecunda:</s>
            <s xml:id="echoid-s50737" xml:space="preserve"> chorda ergo eius, quæ eſt li
              <lb/>
            nea k e, erit 118 partes, 23 minuta, & 20 ſecunda,
              <lb/>
            18 tertia, ſecundum quantitatem, qua diameter
              <lb/>
            q k eſt 120 partes:</s>
            <s xml:id="echoid-s50738" xml:space="preserve"> & ſecundũ quantitatem, qua
              <lb/>
            diameter q k eſt 60, erit chorda k e 59 partes, 11
              <lb/>
            minuta, 40 ſecunda, 9 tertia:</s>
            <s xml:id="echoid-s50739" xml:space="preserve"> ergo ſecundum quantitatẽ, qua linea k e eſt 60, erit linea k q 60 partes,
              <lb/>
            & 48 minuta, & 50 ſecunda.</s>
            <s xml:id="echoid-s50740" xml:space="preserve"> Ablatis itaq;</s>
            <s xml:id="echoid-s50741" xml:space="preserve"> à linea k q partibus 60, quę eſt quantitas lineę k r ſemidia
              <lb/>
            metri terræ:</s>
            <s xml:id="echoid-s50742" xml:space="preserve"> remanet linea r q (quæ eſt ſumma uaporum eleuatio) 48 minuta, & 50 ſecunda, ſecun
              <lb/>
            dum illam quantitatem, qua diameter terræ eſt 120 partes.</s>
            <s xml:id="echoid-s50743" xml:space="preserve"> Et quoniam ſecundum coſmographos
              <lb/>
            maximus circulus terræ ſecundum milliaria eſt notus:</s>
            <s xml:id="echoid-s50744" xml:space="preserve"> ergo ſecundum illum quantitas diametri eſt
              <lb/>
            nota:</s>
            <s xml:id="echoid-s50745" xml:space="preserve"> ergo & linea r q eſt nota.</s>
            <s xml:id="echoid-s50746" xml:space="preserve"> Ethoc eſt propoſitum.</s>
            <s xml:id="echoid-s50747" xml:space="preserve"> Eſt aũt ſecundum cóputationem Abbomadi
              <lb/>
            ex milliarib.</s>
            <s xml:id="echoid-s50748" xml:space="preserve"> (quibus terrę circumferentia eſt 24 000 milliaria) linea r q 51 milliaria, 47 minuta, & 34
              <lb/>
            ſecunda, & 31 tertia ferè.</s>
            <s xml:id="echoid-s50749" xml:space="preserve"> Summum ergo, ad quod eleuantur uapores ſecundum ipſorum conſiſten-
              <lb/>
            tiam, eſt minus quã 52000 paſſuum, ut patere poteſt perquirenti.</s>
            <s xml:id="echoid-s50750" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div1893" type="section" level="0" n="0">
          <head xml:id="echoid-head1389" xml:space="preserve" style="it">61. Ab aqua & aere denſo & uapore rorido reflexionem radiorum corporis luminoſi fieri
            <lb/>
          manifeſtum eſt.</head>
          <p>
            <s xml:id="echoid-s50751" xml:space="preserve">Iſtud in politis corporib.</s>
            <s xml:id="echoid-s50752" xml:space="preserve"> (ut in ſpeculis & ſimilibus) ſenſus comperit, nosq́;</s>
            <s xml:id="echoid-s50753" xml:space="preserve"> in pluribus pręmiſ-
              <lb/>
            ſis huius ſcientiæ libris iſtud ſumus eum amplitudine ſtudij perſequuti.</s>
            <s xml:id="echoid-s50754" xml:space="preserve"> In aqua uerò ſoli expoſita
              <lb/>
            idẽ patet:</s>
            <s xml:id="echoid-s50755" xml:space="preserve"> quia radius in parte ſoli oppoſita uidetur, & maximè ſi locus oppoſitus ſit obſcurus:</s>
            <s xml:id="echoid-s50756" xml:space="preserve"> hoc
              <lb/>
            aũt fit per reflexionẽ.</s>
            <s xml:id="echoid-s50757" xml:space="preserve"> In aere etiam aliqualiter dẽſiore idem euenit:</s>
            <s xml:id="echoid-s50758" xml:space="preserve"> ut quando inſpiſſatus eſt & con
              <lb/>
            ſiſtens quaſi in nubem:</s>
            <s xml:id="echoid-s50759" xml:space="preserve"> tunc enim ab ipſo fit luminis reflexio, ut apparet in crepuſculis ſerotinis &
              <lb/>
            matutinis.</s>
            <s xml:id="echoid-s50760" xml:space="preserve"> Huic etiam atteſtatur quòd tẽpore pluuiali radij ſolis ſępe in aere diſpergũtur, & uix te-
              <lb/>
            nuiter ad terrã pertingunt propter humiditatẽ & groſsiciẽ aeris contrapoſiti ipſi ſoli.</s>
            <s xml:id="echoid-s50761" xml:space="preserve"> Hoc etiã pa-
              <lb/>
            tet:</s>
            <s xml:id="echoid-s50762" xml:space="preserve"> quoniam in aere modicę denſitatis in hyeme, maximè flãte auftro circa lucernas frequenter ui-
              <lb/>
            detur lumen reflecti ſecundum formam circularem:</s>
            <s xml:id="echoid-s50763" xml:space="preserve"> & maximè uiſibus humidis, ad quos de facili fit
              <lb/>
            luminis reflexio & formarum, cum uirtus uiſiua propter debilitatem organi debilitatur, ſic quòd
              <lb/>
            non poteſt denſitatem modicam aeris penetrare, ſed ad ipſum forma rei uiſæ reflectitur ab aere mo
              <lb/>
            dicę denſitatis:</s>
            <s xml:id="echoid-s50764" xml:space="preserve"> ſicut ad uiſus fortes reflectitur ſolũ ab aliquo ſolido peruietatem non habente.</s>
            <s xml:id="echoid-s50765" xml:space="preserve"> Vn-
              <lb/>
            de etiam in uiſu aliquis debilitatus & non acutè uidẽs, propter ophthalmiã uel propter aliud, uidet
              <lb/>
            quandoq;</s>
            <s xml:id="echoid-s50766" xml:space="preserve"> imaginem ſuã in aere groſſo ante ſe, ſicut in ſpeculo, ſtantem contra ſe, & ambulantẽ cum
              <lb/>
            ipſo, quando ipſe ambulat, & reſpicientem ad ipſum.</s>
            <s xml:id="echoid-s50767" xml:space="preserve"> Et ſic quidã notus meus poſt plurium noctiũ
              <lb/>
            uigilias cum cõpulſus nocte ſequente equitaret, formã ſuam, hoc eſt uirũ alium ſecum equitantem
              <lb/>
            </s>
          </p>
        </div>
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