Vitruvius Pollio, I dieci libri dell?architettura, 1567

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                <p type="main">
                  <s id="s.007762">
                    <pb pagenum="420" xlink:href="045/01/434.jpg"/>
                    <emph type="italics"/>
                  uea del Cancro. </s>
                  <s id="s.007763">la quale ſi fa con la lunghezza delle ombre tratta dalla figura
                    <emph.end type="italics"/>
                  11.
                    <emph type="italics"/>
                  ſecondo che
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                  ſi è detto. </s>
                  <s id="s.007764">& a queſto modo ſopra la linea del mezo dì ſegnerai
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                  6.
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                  dalla ſiniſtra
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                  5. 4. 3. 2.
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                    <emph type="italics"/>
                  &
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                  1.
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                  & dalla deſtra
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                  7. 8. 9. 10. 11. 12.
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                  & queſto horologio ſarà nel piano del uerti­
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                  cale, che guarda al mezo dì. </s>
                  <s id="s.007765">Et perche la ſtate il Sole paſſa i termini di Leuante et Ponente, & ua
                    <lb/>
                  uerſo tramontana. </s>
                  <s id="s.007766">però biſognerà nel piano del uerticale, che guarda tramontana ſegnare quelle
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                  hore, che ui uanno, che ſaranno la prima, & la ſeconda, la mattina, & la undecima, & la decima
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                  la ſera. </s>
                  <s id="s.007767">il che farai con lo aiuto del Meridiano. </s>
                  <s id="s.007768">Percioche ſe tirerai a lungo la linea della hiperbo
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                  le, che lega inſieme i termini delle hore del Capricorno, & ſimilmente tirerai in lungo le linee della
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                  undecima, & della prima della decima, & della ſeconda, hora tu hauerai deſcritto le hore, che
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                  uanno alla parte Settentrionale nell'horologio fatto nel piano del uerticale. </s>
                  <s id="s.007769">& con lo iſteſſo ordi­
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                  ne farai gli altri horologi uerticali con le hore a tuo piacere, come praticando auuertirai meglio
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                  di quello, che ſi puo inſegnar con parole, tirando le linee delle hore, che ſono uerſo il Settentrione,
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                  nell'horologio Settentrionale. </s>
                  <s id="s.007770">& le Meridiane nel Meridiano. </s>
                  <s id="s.007771">le figure delle quali ſono qui ſotto
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                  poſte. </s>
                  <s id="s.007772">Seruendoci in tutti la figura I. perche in tutte le ſorti di hore ci ſerue la iſteſſa diuiſione
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                  dello equinottiale.
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                  </s>
                </p>
                <p type="main">
                  <s id="s.007773">
                    <emph type="italics"/>
                  Gli horologi fatti nel piano del Meridiano ſi pigliano dallo Analemma come gli altri; & per­
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                  che l'officio del Meridiano è di ſeparare la parte di Leuante, dalla parte di Ponente, però anche
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                  di queſti horelogi l'uno riguarderà a Leuante, & l'altro a Ponente. </s>
                  <s id="s.007774">Et per fargli ci ſeruiranno
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                  due circonferenze, delle quali l'una (come hauemo detto) cimoſtrerà l'altezza del Sole ſopra il
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                  piano del Meridiano, dal che ſi caueranno le lunghezze delle ombre. </s>
                  <s id="s.007775">L'altra ci moſtrerà le lar
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                  ghezze delle ombre, ſecondo le diſtanze del Sole, dal detto piano. </s>
                  <s id="s.007776">& questa circonferenza ſi
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                  chiamerà Meridiana, & quella ſecondo gli antichi ſepartita in noſtra lingua, & ectemoria in
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                  Greco, quaſi di ſei parti, ſecondo ſei ſiti, che ha l'Orizonte mobile riſpetto alle hore de gli antichi. </s>
                  <s id="s.007777">
                    <lb/>
                  Sia adunque fatta la diuiſione de i tropici, come nello Analemma sì de i ſemicircoli, come de i dia
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                  metri: & le portioni delle hore ne i ſemicircoli ſiano con i numeri delle hore de gli antichi nota­
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                  te. </s>
                  <s id="s.007778">Sia il ſemicircolo del Capricorno di ſotto ſegnato x y. & il ſemicircolo del Cancro di ſopra,
                    <lb/>
                  ſegnato z. </s>
                  <s id="s.007779">&. </s>
                  <s id="s.007780">et la doue ſopra i diametri de i ſemicircoli terminano le linee delle hore ſia poſto n. </s>
                  <s id="s.007781">
                    <lb/>
                  Per ſapere adunque le circonferenze Meridiane per la larghezza delle ombre, biſogna tirare linee
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                  dal centro e. che paſſino per li punti n. & peruenghino alla circonferenza del Meridiano a
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                  b c d. come per eſſempio tirerai una linea occulta dal centro e. che paſſi per lo primo punto
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                  n. della linea delle hore prima, & undecima, & che peruenghi alla circonferenza al punto o.
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                  l'arco adunque, & la circonferenza a o. è l'arco, & la circonferenza Meridiana della pri­
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                  ma, & della undecima hora. </s>
                  <s id="s.007782">Similmente ſe dal centro e. per lo punto del ſecondo n. che è
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                  dell'hora decima, & ſeconda, paſſerà una linea fin alla' circonferenza al punto i. la circonfe­
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                  renza a i. ci ſeruirà per la diſtanza, & per la latitudine dell'ombra della decima, & della
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                  ſeconda hora. </s>
                  <s id="s.007783">A queſto modo ſi caueranno le circonferenze d'hora in hora, & a u. ſarà la
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                  circonferenza Meridiana delle hore terza, & nona. </s>
                  <s id="s.007784">a l. </s>
                  <s id="s.007785">delle hore quarta, & ottaua. </s>
                  <s id="s.007786">a r.
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                  delle hore quinta & ſettima. </s>
                  <s id="s.007787">Ma la ſeſta hora, che è l'hora Meridiana, non cade ſopra quel pia­
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                  no, perche è il piano iſteſſo. </s>
                  <s id="s.007788">Ma gli archi, & le circonferenze ſepartite, per la altezza del So
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                  le, & lunghezza delle ombre ſi pigliano in queſto modo. </s>
                  <s id="s.007789">Sia centro il primo n. & ſpatio n.
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                    <lb/>
                  11. 1.
                    <emph type="italics"/>
                  & ſtando fermo il piede del compaſſo nel centro n. ſia uoltato l'altro piede ſopra il
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                  Meridiano, & fatto punto
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                  11. 1.
                    <emph type="italics"/>
                  la circonferenza, che ſarà tra
                    <emph.end type="italics"/>
                  11. 1.
                    <emph type="italics"/>
                  & lo punto o.
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                  ſarà la circonferenza ſepartita delle hore prima, & undecima. </s>
                  <s id="s.007790">poſto poi il centro nel ſecondo n.
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                  & iſpatio n.
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                  10. 2.
                    <emph type="italics"/>
                  ſtando fermo il piede nel punto n. & uoltato l'altro, ſia ſegnato ſopra'l
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                  Meridiano
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                  10. 2.
                    <emph type="italics"/>
                  & la circonferenza compreſa tra
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                  10. 2.
                    <emph type="italics"/>
                  & il punto e. ſarà l'arco del­
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                  l'altezza del Sole ſopra detto piano. </s>
                  <s id="s.007791">con ſimile uia ſi piglieranno le circonferenze ſepartite delle
                    <lb/>
                  altre hore, sì nel tropico del Capricorno di ſotto, come nel tropico del Cancro diſopra, come uedi
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                  nella figura ſegnata A. & per accommodare nell'horologio le dette circonferenze, & per fug-
                    <emph.end type="italics"/>
                  </s>
                </p>
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            </subchap1>
          </chap>
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