Vitruvius Pollio, I dieci libri dell?architettura, 1567

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    <archimedes>
      <text>
        <body>
          <chap>
            <subchap1>
              <subchap2>
                <p type="main">
                  <s id="s.006996">
                    <pb pagenum="380" xlink:href="045/01/394.jpg"/>
                    <emph type="italics"/>
                  mento del pianeta. </s>
                  <s id="s.006997">Et anche aggiuntaui queſta conditione in quanto a tutti, che i diametri dello
                    <lb/>
                  eccentrico, & del conceutrico, ſiano proportionati al ſemidiametro dello epiciclo. </s>
                  <s id="s.006998">& alla uſcita
                    <lb/>
                  del centro, & coſi all'uno, & all'altro modo nelle ſtelle erranti ſi potria difendere la ragione del
                    <lb/>
                  progreſſo, & del regreſſo quanto alla diuerſità, & uarietà. </s>
                  <s id="s.006999">Ma come per lunga iſperienza gli
                    <lb/>
                  oſſeruatori delle ſtelle hanno compreſo questa prima diuerſirà uariarſi da una ſeconda diuerſità,
                    <lb/>
                  però fu neceſſario dare la prima diuerſità allo epiciclo, & difendere la ſeconda col Deferente. </s>
                  <s id="s.007000">
                    <lb/>
                  Ma quella ſola coſa era aſſai baſteuole a fare, che i Deferenti di tutti i pianeti non faceſſero uno
                    <lb/>
                  iſteſſo centro, cioè la ſingularità del mouimento, perche i concentrici communicano il mouimen­
                    <lb/>
                  to il ſuperiore allo inferiore. </s>
                  <s id="s.007001">Ma questa communicatione non è ſtata auuertita ne i proprij mo­
                    <lb/>
                  uimenti de i pianeti, però non è ſtato poſſibile di dare loro i concentrici.
                    <emph.end type="italics"/>
                  </s>
                </p>
                <figure id="id.045.01.394.1.jpg" xlink:href="045/01/394/1.jpg" number="118"/>
                <p type="main">
                  <s id="s.007002">
                    <emph type="italics"/>
                  h K. lo epiciclo b. il ſuo centro.
                    <emph.end type="italics"/>
                  </s>
                </p>
                <p type="main">
                  <s id="s.007003">
                    <emph type="italics"/>
                  h. il ſuo giogo. </s>
                  <s id="s.007004">n. l'oppoſto.
                    <emph.end type="italics"/>
                  </s>
                </p>
                <p type="main">
                  <s id="s.007005">
                    <emph type="italics"/>
                  K. il punto della prima dimora.
                    <emph.end type="italics"/>
                  </s>
                </p>
                <p type="main">
                  <s id="s.007006">
                    <emph type="italics"/>
                  c. il centro del Mondo.
                    <emph.end type="italics"/>
                  </s>
                </p>
                <p type="main">
                  <s id="s.007007">
                    <emph type="italics"/>
                  o. il punto della ſeconda dimora.
                    <emph.end type="italics"/>
                  </s>
                </p>
                <p type="main">
                  <s id="s.007008">
                    <emph type="italics"/>
                  h l K. l'arco della prima dimora.
                    <emph.end type="italics"/>
                  </s>
                </p>
                <p type="main">
                  <s id="s.007009">
                    <emph type="italics"/>
                  h K o. l'arco della ſeconda dimora.
                    <emph.end type="italics"/>
                  </s>
                </p>
                <p type="main">
                  <s id="s.007010">
                    <emph type="italics"/>
                  K n o. l'arco del regreſſo.
                    <emph.end type="italics"/>
                  </s>
                </p>
                <p type="main">
                  <s id="s.007011">
                    <emph type="italics"/>
                  o h K. l'arco della direttione.
                    <emph.end type="italics"/>
                  </s>
                </p>
                <p type="main">
                  <s id="s.007012">
                    <emph type="italics"/>
                  Ma accioche egli s'intenda a quali pianeti ſi dia il progreſſo, dirò, che
                    <lb/>
                  douemo imaginare due linee dritte tirate dal centro, l'una, che termini nelle
                    <lb/>
                  parti orientali dello epiciclo, l'altra nelle occidentali. </s>
                  <s id="s.007013">A queſto modo quan
                    <lb/>
                  to al mouimento del pianeta nello epiciclo ſolamente, la ſtella, che anderà
                    <lb/>
                  per l'arco di ſopra i due punti del toccamento delle dette linee, ſi dirà andar
                    <lb/>
                  inanzi, & far progreſſo. </s>
                  <s id="s.007014">Perche ella in quel luogo ſarà portata uerſo l'orien
                    <lb/>
                  te? </s>
                  <s id="s.007015">ma nello arco inferiore ſi dirà retrograda, o far regreſſo, perche ritorne
                    <lb/>
                  rà mouendoſi alla contraria parte: ma ſtando ne i predetti punti, ſi dirà, che
                    <lb/>
                  dimori, & stia: perche nel punto orientale di dritta ſi farà retrograda, &
                    <lb/>
                  nello occidentale di retrograda ſi farà dritta. </s>
                  <s id="s.007016">Benche queſte coſe per lo contrario ſono conſidera
                    <lb/>
                  te nel Sole, & nella Luna. </s>
                  <s id="s.007017">La qual ragione ſarebbe a baſtanza cerca il regreſſo, & progreſſo,
                    <lb/>
                  ſe il pianeta non ſi trouaſſe con altro mouimento, che col mouimento dello epiciclo. </s>
                  <s id="s.007018">Ma perche
                    <lb/>
                  mentre il pianeta ſi riuolge nello epiciclo, anche lo epiciclo dallo eccentrico è portato, però che
                    <lb/>
                  appreſſo i detti punti del toccamento il pianeta, benche quanto al riuolgimento dello epiciclo ſia
                    <lb/>
                  in dimora, niente di meno è portato dallo eccentrico uerſo oriente, & coſi anchora è diretto: &
                    <lb/>
                  però è neceſſario, che i punti delle dimore ſiano alquanto inferiori a quelli punti, che le predette
                    <lb/>
                  linee fanno nel toccamento, le quali noi dicemmo partirſi dal centro: & coſi quelle linee non toc
                    <lb/>
                  cando, ma tagliando, & partendo lo epiciclo ne i loro tagli fanno i punti della dimora. </s>
                  <s id="s.007019">Et però
                    <lb/>
                  egli è neceſſario, che quelli punti ſiano in quella parte della circonferenza dello epiciclo, done il
                    <lb/>
                  mouimento retrogrado al pianeta nello epiciclo coſi contraſta col mouimento del Deferente, che
                    <lb/>
                  quanto il pianeta è portato all'occidente dallo epiciclo tanto lo epiciclo ſia ritornato dal Deferen
                    <lb/>
                  te uerſo l'Oriente. </s>
                  <s id="s.007020">Et a queſto modo il pianeta portato da eguali ma contrarij mouimenti, pare,
                    <lb/>
                  che egli ſaccia dimora: Et però il pianeta nel punto dello stato orientale, che è detto prima dimo
                    <lb/>
                  ra, comincia a ritornare; imperoche in quel luogo il mouimento del pianeta nello epiciclo comin­
                    <lb/>
                  cia auanzare il mouimento dello epiciclo nel Deferente. </s>
                  <s id="s.007021">ma nel punto della dimora occidentale,
                    <lb/>
                  che ſi chiama ſeconda dimora il pianeta ritorna allo andar auanti, & al progreſſo, percioche il
                    <lb/>
                  mouimento del pianeta, nello epiciclo ſi rallenta. </s>
                  <s id="s.007022">Et queste coſe dalla figura ſono manifeste.
                    <emph.end type="italics"/>
                  </s>
                </p>
              </subchap2>
            </subchap1>
          </chap>
        </body>
      </text>
    </archimedes>
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