Biancani, Giuseppe, Aristotelis loca mathematica, 1615

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              <s id="s.002058">
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              tiarum data eſt. </s>
              <s id="s.002059">apud autem aliud punctum, quam ipſius M N, circunferentiæ, ab
                <lb/>
              ijſdem punctis, eadem ratio in eodem plano non conſiſtit)
                <emph.end type="italics"/>
              eorum omnium, quæ
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              demonſtranda ſunt, præmittenda ſunt duo neceſſaria fundamenta. </s>
              <s id="s.002060">Primum
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              eſt; ea, quæ videmus per reflexionem ſub quopiam angulo, manentibus no­
                <lb/>
              bis ſpeculo, & obiecto ijſdem in locis, non poſſunt videri ſub alio diuerſo
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              angulo, nec alibi conſequenter apparere. </s>
              <s id="s.002061">v. g. in ſuperiori figura, quam
                <lb/>
              textui reſtituimus exiſtente Sole in G, oculo in K, & nube in M. ex qua ra­
                <lb/>
              dius Solis G M, reflectatur ad viſum in K, per
                <expan abbr="lineã">lineam</expan>
              M K, ſub angulo G M K,
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              impoſſibile eſt manentibus illis, vt dixi, videri Solem in nube M, ſub diuer­
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              ſo angulo à priori, nec alibi apparere. </s>
              <s id="s.002062">Alterum eſt apud Opticos vulga­
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              tum; ea ſcilicet, quæ per reflexionem (de quorum numero eſt Iris) viden­
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              tur, videri, tunc ſolum, quando angulus incidentiæ fuerit æqualis angulo
                <lb/>
              reflexionis, quia tunc breuiſſimis lineis fit viſio; quibus ſoli, natura (ſi fieri
                <lb/>
                <figure id="id.009.01.117.1.jpg" place="text" xlink:href="009/01/117/1.jpg" number="59"/>
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              poteſt) vtitur. </s>
              <s id="s.002063">v. g. in figura præſenti ſit ſpe­
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              culum C D E, obiectum A, oculus B, linea in­
                <lb/>
              cidentiæ eſt A D, & angulus pariter inciden­
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              tiæ eſt A D C. linea verò D B, eſt linea refle­
                <lb/>
              xionis, & angulus pariter reflexionis eſt B D­
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              E, qui duo anguli niſi fuerint æquales, nun­
                <lb/>
              quam videbitur obiectum A, ab oculo B, hinc
                <lb/>
              eſt, quod aliquando poſito ſpeculo, obiectum
                <lb/>
              quamuis illi aduerſum, à nobis pariter ante
                <lb/>
              ſpeculum conſtitutis, videri nequit, quia ſci­
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              licet in tali poſitione ſpeculi, obiecti, & noſtri, nulla linea incidentiæ, ideſt,
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              quæ ab obiecto in ſpeculum tendit, facere poteſt angulum cum ſpeculo, qui
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              dicitur angulus incidentiæ, æqualem angulo illi, quem facit linea eadem re­
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              flexa à ſpeculo ad oculum, quem dicunt angulum reflexionis. </s>
              <s id="s.002064">Cum ergo in
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              Iride videamus colorem Solis per reflexionem, tunc ſolum apparebit Iris,
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              quando Sol, nubes, & oculus fuerint in ea conſtitutione, qua radius
                <expan abbr="incidẽs">incidens</expan>
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              nubi, & radius à nube repercuſſus faciant pares angulos. </s>
              <s id="s.002065">Et quia quando
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              nubes roſcida perpendiculariter opponitur Soli, & nobis, poſſunt fieri præ­
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              dicti anguli æquales non in vno loco nubis, ſed in pluribus, conſtitutis ta­
                <lb/>
              men in circuli periphæria, hinc fit, quod Solis color reflectatur ex pluribus
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              locis in orbem conſtitutis, quæ reflexio eſt ipſius Iridis arcus. </s>
              <s id="s.002066">ex Vitellion
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              63. 10. Totam autem figuræ Iridis demonſtrationem ſic breuiter puto ad­
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              inuentam eſſe. </s>
              <s id="s.002067">cum Sol in Iride videatur in orbem,
                <expan abbr="atq;">atque</expan>
              conſimiliter, ne ceſ­
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              ſe eſt id prouenire ex angulis reflexionum conſimilibus, ſiue æqualibus: diſ­
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              ſimiles enim anguli, diſſimilem
                <expan abbr="vtiq;">vtique</expan>
              efficiunt Solis
                <expan abbr="apparẽtiam">apparentiam</expan>
              . </s>
              <s id="s.002068">atqui con­
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              ſimiles anguli, ſiue æquales, non niſi in orbem poſſunt conſtitui; igitur an­
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              gulorum æqualitas cauſa erit rotundationis arcus. </s>
              <s id="s.002069">hęc eſt ſumma totius di­
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              ſcurſus, quem pluribus, & nimis obſcurè Ariſt. explicat.</s>
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              <s id="s.002070">Inquit igitur Ariſt. ſit enim in oriente, &c. </s>
              <s id="s.002071">vbi aggreditur probare vnum
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              ex tribus illis, quæ ſupra propoſuit, nimirum tunc Iridem eſſe ſemicircu­
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              lum, quando aſtrum fuerit in oriente, ſiue in horizonte, vbi G. ſi igitur per
                <lb/>
              triangulum G M K, intelligamus
                <expan abbr="planũ">planum</expan>
              extenſum, in quo A, in figura, adeo
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              magnum, vt totum ſecet hemiſphærium, faciet in ſuperficie hemiſphærij </s>
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