Vitruvius, I Dieci Libri dell' Architettvra di M. Vitrvvio, 1556

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        <div xml:id="echoid-div634" type="section" level="1" n="112">
          <pb o="213" file="0223" n="232" rhead="NONO."/>
          <p>
            <s xml:id="echoid-s18669" xml:space="preserve">Ma la Stella di Venere, & </s>
            <s xml:id="echoid-s18670" xml:space="preserve">di Mercurio girandoſi intorno i raggi del Sole, & </s>
            <s xml:id="echoid-s18671" xml:space="preserve">cignendo à torno con i loro uiaggi il Sole
              <lb/>
            come Centro fanno i ritorni loro; </s>
            <s xml:id="echoid-s18672" xml:space="preserve">& </s>
            <s xml:id="echoid-s18673" xml:space="preserve">ancho fermandoſi fanno dimora ne gli ſpacij de i ſegni. </s>
            <s xml:id="echoid-s18674" xml:space="preserve">Et che ciò ſia ueramente
              <lb/>
            ſi fa chiaro dalla Stella di Venere, percioche ſeguitando ella il Sole, & </s>
            <s xml:id="echoid-s18675" xml:space="preserve">apparendoci doppò il tramontar di quello, & </s>
            <s xml:id="echoid-s18676" xml:space="preserve">
              <lb/>
            lucendo chiarisſimamente, ſi chiama per queſto Veſperugine, & </s>
            <s xml:id="echoid-s18677" xml:space="preserve">quando in altri tempi che gli ua inanzi, & </s>
            <s xml:id="echoid-s18678" xml:space="preserve">ſi lieua in
              <lb/>
            anzi il giorno, ſi chiama Lucifer. </s>
            <s xml:id="echoid-s18679" xml:space="preserve">& </s>
            <s xml:id="echoid-s18680" xml:space="preserve">per quello alcune fiate piu giorni in un ſegno dimorano, alcune fiate piu pre-
              <lb/>
            ſto entrano in un’altro, & </s>
            <s xml:id="echoid-s18681" xml:space="preserve">però non egualmente compieno il numero de i giorni in ciaſcuno de i ſegni, quanto hanno
              <lb/>
            prima rittardato, tanto con piu ueloce corſo paſſando agguagliano il camino, & </s>
            <s xml:id="echoid-s18682" xml:space="preserve">lo pareggiano perfettamente, & </s>
            <s xml:id="echoid-s18683" xml:space="preserve">co-
              <lb/>
            ſi naſce, che auegna, che dimorino in alcuni ſegni, niente di meno poi, che ſi tolgono dalla necesſita della tardanza
              <lb/>
            preſtamente conſeguiſcono il giuſto circoito. </s>
            <s xml:id="echoid-s18684" xml:space="preserve">Ma la Stella di Mercurio coſi paſſa il ſuo corſo nel cielo, che correndo
              <lb/>
            per gli ſpacij de i ſegni in giorni 360 ritorna à quel ſegno, di dõde ella ſi parti prima, & </s>
            <s xml:id="echoid-s18685" xml:space="preserve">il ſuo uiaggio coſi s’agguaglia
              <lb/>
              <note position="left" xlink:label="note-0223-01" xlink:href="note-0223-01a" xml:space="preserve">10</note>
            che da 30 giorni in ogni ſegno habbia la ragione del ſuo numero. </s>
            <s xml:id="echoid-s18686" xml:space="preserve">Ma Venere quando è libera dall’impedimento de i
              <lb/>
            raggi del Sole in 30 giorni trappaſſa lo ſpacio d’un ſegno, quanto meno in giorni 40 in ciaſcun ſegno patiſce, quan
              <lb/>
            do ella hauerà finito la ſua dimora reſtituiſce quella ſomma di mumero dimorãdo in un ſegno: </s>
            <s xml:id="echoid-s18687" xml:space="preserve">Et però hauẽdo Vene-
              <lb/>
            re miſurato lo intiero circuito del cielo in 485 giorni, torna di nuouo al ſegno iſteſſo di doue cominciò il ſuo uiaggio.</s>
            <s xml:id="echoid-s18688" xml:space="preserve"/>
          </p>
          <p style="it">
            <s xml:id="echoid-s18689" xml:space="preserve">In queſta parte Vitr. </s>
            <s xml:id="echoid-s18690" xml:space="preserve">è difficile non concorda con gli altri, & </s>
            <s xml:id="echoid-s18691" xml:space="preserve">for ſe è ſcorretto: </s>
            <s xml:id="echoid-s18692" xml:space="preserve">Plinio, che ſuole pigliar le facciate intiere da Vitr. </s>
            <s xml:id="echoid-s18693" xml:space="preserve">in questa parte
              <lb/>
            è tutto diuerſo Vitr. </s>
            <s xml:id="echoid-s18694" xml:space="preserve">pone i pianeti neceßitati tardare, gli ſcioglie dalla neceßità, & </s>
            <s xml:id="echoid-s18695" xml:space="preserve">quaſi slegandoli uuole, che pareggino-con la uelocità d@i
              <unsure/>
              <lb/>
            corſo, quel uiaggio, che haueriano fatto ſe ſempre fuſſe ſtato loro conceſſa la libertà di caminare, ne cidichi. </s>
            <s xml:id="echoid-s18696" xml:space="preserve">ra come ſi cõuiene con approuate
              <lb/>
            dimostrationi doue naſca queſta neceßità, & </s>
            <s xml:id="echoid-s18697" xml:space="preserve">donde uegna la loro libertà, però neceſſirio ci pare darne un poco di lume con quelle coſe, che da
              <lb/>
            poi Vitr.</s>
            <s xml:id="echoid-s18698" xml:space="preserve">con belli fondamẽti ſono ſtate ritrouate da gli ſtudioſi, et però la neceßità ci conduce à far quello, che noiuoleuamo ſugga
              <unsure/>
            re, però dich
              <unsure/>
            a
              <lb/>
            riremo alcuni termini, che ſono al propoſito nostro. </s>
            <s xml:id="echoid-s18699" xml:space="preserve">& </s>
            <s xml:id="echoid-s18700" xml:space="preserve">ſono queſti. </s>
            <s xml:id="echoid-s18701" xml:space="preserve">Epiciclo, Defcrente, Eccentrico, Concentrico, Giogo, opposto al giogo,
              <lb/>
              <note position="left" xlink:label="note-0223-02" xlink:href="note-0223-02a" xml:space="preserve">20</note>
            longhezza media dello Eccentrico, longhezza media dello Epiciclo. </s>
            <s xml:id="echoid-s18702" xml:space="preserve">Stato, Ritorno, Progreſſo, Argomento, Agguaghamento. </s>
            <s xml:id="echoid-s18703" xml:space="preserve">E adunque
              <lb/>
            Epiciclo, quello, che circolo della diuerſità ſi chiama da Ptolomeo, un picciol circolo imaginato come aggiunta del circolo grande, che coſi ſigni
              <lb/>
            fica la parola Greca d’intorno la cui circonferenza uogliono gli Astronomi, che ſi uolga il corpo del pianeta, il cui centro è nella circonfiren-
              <lb/>
            za di quel circolo, che porta il pianeta, ouero l’Epiciclo uerſo l’Oriente, detto Df@rente, il cui Centro non è lo iſteſſo con il Centro del Mondo
              <lb/>
            però egli ſi chiama Eccentrico, cioèfuori del Cẽtro, ſi come ſi chiama Concentrico quel circolo, che ha lo ſteſſo centro con quello del mondo, pe
              <lb/>
            rò uolendo noi nel piano ſormare lo Epiciclo, & </s>
            <s xml:id="echoid-s18704" xml:space="preserve">il Deferente, maginamo il centro c. </s>
            <s xml:id="echoid-s18705" xml:space="preserve">dalquale eſce una linea l’altro capo dellaquale ſia a. </s>
            <s xml:id="echoid-s18706" xml:space="preserve">ct que
              <lb/>
            ſto ſia il centro dello Epiciclo: </s>
            <s xml:id="echoid-s18707" xml:space="preserve">Faccia questo capo a un giro perſetto ſtando ſermo l’altro nel punto c. </s>
            <s xml:id="echoid-s18708" xml:space="preserve">dico, che nel piano former à una ſuperſi-
              <lb/>
            cie, & </s>
            <s xml:id="echoid-s18709" xml:space="preserve">questa ſer à la circonferenza del deferente, coſi formail Sole l’Eclittica, che è come deferente del Sole, dallaquale i deferenti de gli altri
              <lb/>
            pianeti ſono diſtanti, & </s>
            <s xml:id="echoid-s18710" xml:space="preserve">piegano dailati, & </s>
            <s xml:id="echoid-s18711" xml:space="preserve">prolongata la iſteſſa linea fin alla
              <lb/>
            concaua ſoperficie del primo ci@lo diſſegna in eſſa una circõferenza dello iſteſſo
              <lb/>
              <figure xlink:label="fig-0223-01" xlink:href="fig-0223-01a" number="120">
                <description xml:id="echoid-description97" xml:space="preserve">a b il Deferente.
                  <lb/>
                c il ſuo Centro.
                  <lb/>
                d e l’Epiciclo.
                  <lb/>
                a il ſuo Centro.
                  <lb/>
                f. il centro del Mondo.
                  <lb/>
                a il Giogo del Deferen
                  <lb/>
                te.
                  <lb/>
                b l’oppoſto.
                  <lb/>
                d il Giogo dell Epici
                  <lb/>
                clo.
                  <lb/>
                e l’oppoſto.</description>
                <variables xml:id="echoid-variables50" xml:space="preserve">d a e c f b</variables>
              </figure>
            nome: </s>
            <s xml:id="echoid-s18712" xml:space="preserve">il cẽtro dell’ Epiciclo è ſempre nella circonferenza del Deferẽte poſto a-
              <lb/>
            dunque un piede della ſeſta nel punto. </s>
            <s xml:id="echoid-s18713" xml:space="preserve">a. </s>
            <s xml:id="echoid-s18714" xml:space="preserve">& </s>
            <s xml:id="echoid-s18715" xml:space="preserve">allargato l’altre fin che tocchi il
              <lb/>
            centro del pianeta d. </s>
            <s xml:id="echoid-s18716" xml:space="preserve">girandoſi à torno ſi far à l’Epiciclo, ſtando adunque le gia
              <lb/>
            dette coſe, non è niuno, che nõ ueda la circonferẽza del Deferente, & </s>
            <s xml:id="echoid-s18717" xml:space="preserve">la circonfe
              <lb/>
            renza dello Epiciclo eſſer diſegualmente diſtanti dal centro del mondo f. </s>
            <s xml:id="echoid-s18718" xml:space="preserve">Dapoi
              <lb/>
            gli Astronomihãno trouato diuerſi uocaboli alle parti dello Epiciclo ſecõdo le
              <lb/>
            diſtanze loro dal Centro uniuerſale uolendo con quelle dimostrarci come ſi ſal
              <lb/>
            ua la diuerſità delle apparenze, la doue quel punto, che è nella cir conferenza
              <lb/>
            del deferente, ò dello Epiciclo piu rimoto dal centro del mondo chiamano giogo
              <lb/>
            quaſi ſommita, che iugum è da Cicerone chiamato quello, che auge barbaramen
              <lb/>
            te ſi dice, & </s>
            <s xml:id="echoid-s18719" xml:space="preserve">quel punto, che per diametro s’oppone al giogo, nominarono l’op-
              <lb/>
            poſto algiogo. </s>
            <s xml:id="echoid-s18720" xml:space="preserve">Et perche al Sole non danno Epiciclo, ma deferente, però quel punto, che nel deferente ſarà oppoſto alla ſommità, ſimilmente ſi
              <lb/>
            chiamer à oppoſto al giogo. </s>
            <s xml:id="echoid-s18721" xml:space="preserve">Giogo, cima, auges, abſides, ſono parole di una ſteſſa coſa. </s>
            <s xml:id="echoid-s18722" xml:space="preserve">Lõghezza media dello Eccẽtrico è la meta del Diametro.
              <lb/>
            </s>
            <s xml:id="echoid-s18723" xml:space="preserve">lunghezza media dello Epiciclo é lo ſpacio, ch’è da un centro all’ altro, chiamanſi longhezze medie riſpetto che quel punto, che è rimotißuno dal
              <lb/>
            centro del mondo, che ſi chiama giogo, è detto ancho longhezza piu lõtana, & </s>
            <s xml:id="echoid-s18724" xml:space="preserve">quello, che è uicinißimo al detto centro, che chiamano opposto al
              <lb/>
            giogo, è detto ancho longhezza piu uicina dello Eccentrico, ouero dello Epiciclo. </s>
            <s xml:id="echoid-s18725" xml:space="preserve">Queſti due punti, ſono termini di una linea dritta, che paſſa
              <lb/>
            per amẽdua i centri, laquale ſi chiama linea del giogo, percioche è dimoſtratrice del giogo. </s>
            <s xml:id="echoid-s18726" xml:space="preserve">La onde ſi come nello Eccẽtrico la maggior lontanan
              <lb/>
            Za, è tanto piu del ſemidiam@tro dello Eccentrico, quanto è lo ſpatio, ch’ è tra uno centro, & </s>
            <s xml:id="echoid-s18727" xml:space="preserve">l’altro, coſi la minore, è tanto meno del ſemidiame-
              <lb/>
            tro quanto quella è di piu, & </s>
            <s xml:id="echoid-s18728" xml:space="preserve">eſſo ſemidiametro è la lòghezza media. </s>
            <s xml:id="echoid-s18729" xml:space="preserve">Similmẽte, nello Epiciclo la lunghezza maggiore, ſera tãto di piu di uno
              <lb/>
            ſpacio, che è tra uno centro, & </s>
            <s xml:id="echoid-s18730" xml:space="preserve">l’altro, quanto è il Semidiametro dello Epiciclo, et tãto dallo steſſo ſpacio ſer à ſuperata la minore, la onde lo ſpa
              <lb/>
              <note position="left" xlink:label="note-0223-03" xlink:href="note-0223-03a" xml:space="preserve">50</note>
            cio, che è tra uno centro & </s>
            <s xml:id="echoid-s18731" xml:space="preserve">l’altro, ſerà la diſtanza di mezzo, che media longhezza ſi chiama, percioche è molto ragioneuole, che la lõghezza
              <lb/>
            media ſia tanto meno della maggiore, quanto eſſa è di piu della minore. </s>
            <s xml:id="echoid-s18732" xml:space="preserve">Da quello, che detto hauemo chi l’hauer à ben conſiderato, comprenderà,
              <lb/>
            che tanto nello Eccentrico, quanto nello Epiciclo qualunque punto quãto ſi ritrouer à nella circõſerenza piu rimoto, è diſcosto dalla lõghezza
              <lb/>
            maggiore tanto ſerà piu uicino al centro della terra, & </s>
            <s xml:id="echoid-s18733" xml:space="preserve">quelli punti, che ſeranno egualmente diſtanti dal punto del giogo, ſeranno anche egual
              <lb/>
            mente diſtanti dal centro della terra. </s>
            <s xml:id="echoid-s18734" xml:space="preserve">Di qui ſia ha tutta la diuerſità del mouimento, che ci appare, anzi con queſte deſcrittioni ſi ſalua la diuerſi
              <lb/>
            tà, delle apparenze, & </s>
            <s xml:id="echoid-s18735" xml:space="preserve">però molto cautamente ſi deono intendere questi uocaboli, iquali ſono ſtati ritrouati per dare ad intendere le coſe del cie
              <lb/>
            lo à quel modo, che ſi può, perche non ſi troua, ne Epiciclo ne giogo, ne deſerente, ne altra coſa ſimigliante nel mondo. </s>
            <s xml:id="echoid-s18736" xml:space="preserve">Vediamo adunque come
              <lb/>
            ſi troua la diuerſità de i mouimenti, poniamo caſo, che’l pianeta ſi moua portato ſenza mezzo dal ſuo Eccentrico, benche egli ſi moua egualmen
              <lb/>
            te ſopra il ſuo propio centro, non dimeno pare, che egli mutail ſuo tenore ſopra qualunque altro, punto, che ſia nel cerchio, et ſimilmẽte ſopra
              <lb/>
            il centro del mondo, queſta mutatione ſi ſalua per ragione di proſpettiua, imperoche poſto, che molte coſe cõ egual uelocità ſi mouino, pur quel-
              <lb/>
              <note position="left" xlink:label="note-0223-04" xlink:href="note-0223-04a" xml:space="preserve">60</note>
            le, che ſono da noi piu lontane, pareno men ueloci; </s>
            <s xml:id="echoid-s18737" xml:space="preserve">& </s>
            <s xml:id="echoid-s18738" xml:space="preserve">però hauendo gli Aſtronomi compreſo, che il Sole in diuerſi luoghi del Zodiaco diuerſamẽ
              <lb/>
            te ſi moueua, & </s>
            <s xml:id="echoid-s18739" xml:space="preserve">uolendo ſaluare tanta diuerſità, & </s>
            <s xml:id="echoid-s18740" xml:space="preserve">non uolendo dare ad un corpo ſi nobile tanta diſaguaglianza, ſi hanno imaginato diuerſe
              <lb/>
            sſere, ò cerchi, i centri de iqualinon fuſſero i medeſimi colcentro del mondo. </s>
            <s xml:id="echoid-s18741" xml:space="preserve">Egli adunque adiuiene, che piu lenta ci appare una ſtella eſſendo nel
              <lb/>
            giogo, che lontana dal giogo, perche nel giogo è piu rimota. </s>
            <s xml:id="echoid-s18742" xml:space="preserve">Ecci un’altro modo di diuerſità nel mouimento, perche ſe il pianeta dallo Epiciclo,
              <lb/>
            & </s>
            <s xml:id="echoid-s18743" xml:space="preserve">l’Epiciclo dal Cõcentrico portato fuſſe, nõ ceſſarebbe la diuerſità, imperoche il pianeta portato dall’uno, et l’altro uerſo Leuãte ſenza
              <lb/>
            dubbio andrebbe piu ueloce, che ſe portato fuſſe dal cõcentrico ſolo, et per lo Epiciclo ſe ne tornaſſe à dietro, percioche nel tocca-
              <lb/>
            mento di quelle linee, che ſi partono dal centro, & </s>
            <s xml:id="echoid-s18744" xml:space="preserve">uanno all’Epiciclo, pare che la ſtella quãto al mouimento dello Epiciclo, ſi stia:</s>
            <s xml:id="echoid-s18745" xml:space="preserve">ma in una me-
              <lb/>
            tà della circõferenza pare, ehe uada inãzi, et nell’altra pare, cher ritorni. </s>
            <s xml:id="echoid-s18746" xml:space="preserve">Ecco lo eſſempio. </s>
            <s xml:id="echoid-s18747" xml:space="preserve">imaginiamo che uno cauallo corra intorno un cerchio
              <lb/>
            grãdißimo, et un’huomo fuori del cerchio lõtano ſtia fermo à guardare, certo è che quel cauallo gli parera, hora tardo, hora ueloce, hora fermo
              <lb/>
            hora andar inanzi, hora tornar à drieto benche egualmente ſi moua, et questo adiuiene per la natura del circolo, fatto di contrari come dice A-
              <lb/>
              <note position="left" xlink:label="note-0223-05" xlink:href="note-0223-05a" xml:space="preserve">70</note>
            rist. </s>
            <s xml:id="echoid-s18748" xml:space="preserve">nelle Mechan. </s>
            <s xml:id="echoid-s18749" xml:space="preserve">Coſi il pianeta nell’ arco di ſopra, nel toccamento di queſte linee parerà fermo à noi, che ſtiamo al baſſo, ma nel luogo oppo-
              <lb/>
            ſto alla cima ci parer à uelocißimo, & </s>
            <s xml:id="echoid-s18750" xml:space="preserve">ſimilmente nella cima alcuna uolta piu lento, ma nello arco di ſopra dello Epiciclo dapoi il toccamento
              <lb/>
            delle linee, il Sole, ſe egli haueſſe Epiciclo, et la Luna ſarian portati da Leuãte à Ponente, ma nello arco inferiore ſarino portate dal deferente.
              <lb/>
            </s>
            <s xml:id="echoid-s18751" xml:space="preserve">Ma gli altri pianeti hanno contrario mouimento, dalche auuiene, che il mouimento del pianeta, è di due mouimenti compoſto, l’uno è dello Epi-
              <lb/>
            ciclo, l’altro del Deferente, come ſe uno fuſſe da una Galera portato inanzi, & </s>
            <s xml:id="echoid-s18752" xml:space="preserve">egli in quel mezzo andaſſe à torno i fori, la doue ſe l’uno, & </s>
            <s xml:id="echoid-s18753" xml:space="preserve">l’al
              <lb/>
            tro mouimẽto ſerà uerſo Leuante, allhora eſſendo il pianeta da due
              <unsure/>
            mouimenti portato, piu uelocemente ſi mouerà, come ſe uno da una Galera
              <lb/>
            portato inanzi, egli ſimilmente andaſſe da poppa à proua.</s>
            <s xml:id="echoid-s18754" xml:space="preserve"/>
          </p>
        </div>
      </text>
    </echo>
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