Vitruvius, De architectura libri decem, 1567

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              <s xml:id="echoid-s21854" xml:space="preserve">
                <pb o="288" file="514.01.320" n="320" rhead="LIBER"/>
              conſentaneum eſt mediam longitudinem tan to minorem eſſe maiori, quanto ipſa est maior minori. </s>
              <s xml:id="echoid-s21855" xml:space="preserve">Ex his be-
                <lb/>
              te conſideratis elicitur ſignum omne inuentum tam in eccentrico, quàm in epicyclo in circinatione, quo remo-
                <lb/>
              ius a maiori longitudine aberit, eo centro terræ propinquius futurum, & </s>
              <s xml:id="echoid-s21856" xml:space="preserve">ſigna, quæ æqualiter a iugo abe-
                <lb/>
              runt, æque etiam a terræ centro aberunt. </s>
              <s xml:id="echoid-s21857" xml:space="preserve">Ex his omnis apparens motuum diuerſitas conſideratur: </s>
              <s xml:id="echoid-s21858" xml:space="preserve">immo his
                <lb/>
              obſeruationibus ſeruatur eorum, quæ uidentur, diuerſitas. </s>
              <s xml:id="echoid-s21859" xml:space="preserve">ideo quàm cautiſſimè ea uocabula ſunt perpen-
                <lb/>
              denda, quoniam ad id inuenta ſunt, ut eo, quo poſſumus modo, cœleſtes res, earumq́; </s>
              <s xml:id="echoid-s21860" xml:space="preserve">motiones declaremus:
                <lb/>
              </s>
              <s xml:id="echoid-s21861" xml:space="preserve">quoniam neque epicyclum, nec iugum, nec deferens, nec aliud quippiam in cœlo inuenimus. </s>
              <s xml:id="echoid-s21862" xml:space="preserve">Videamus ergo
                <lb/>
              qua ratione motuum diuerſitas deprebendatur. </s>
              <s xml:id="echoid-s21863" xml:space="preserve">Statuatur ſydus moueri, atque a ſuo eccentrico ſine medio
                <lb/>
              deferri, licet æquabiliter ſuper ſuo centro moueatur, tamen tenorem ſuum mutare uidebitur ſigno quolibet in
                <lb/>
              circinatione mutato, & </s>
              <s xml:id="echoid-s21864" xml:space="preserve">ad centrum mundi uariam rationem habebit. </s>
              <s xml:id="echoid-s21865" xml:space="preserve">Ratio hæc optica inſpectione ſeruatur
                <lb/>
                <note position="left" xlink:label="note-514.01.320-01" xlink:href="note-514.01.320-01a" xml:space="preserve">10</note>
              nam licet multa æquabili celeritate moueantur, tamen quæ longius abſunt, minus celeriter moueri uidentur,
                <lb/>
              quàm proxima. </s>
              <s xml:id="echoid-s21866" xml:space="preserve">Quare cum ſyderum obſeruatores cognouerint Solem in diuerſis ſigniferi partibus, diuerſis
                <lb/>
              modis moueri, cum uellent diuerſitatem huiuſmodi ſeruare, & </s>
              <s xml:id="echoid-s21867" xml:space="preserve">nollent tam diuino corpori tantam inæquabi-
                <lb/>
              litatem tribuere, plures orbes commenti ſunt, quorum centra non eſſent eodem loco, in quo centrum mundi
                <lb/>
              collocatur. </s>
              <s xml:id="echoid-s21868" xml:space="preserve">Accidit igitur tardiorem uideri ſyderis motum cum in iugo eſt, quàm alio in loco circinationis a iu-
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              go remoto. </s>
              <s xml:id="echoid-s21869" xml:space="preserve">Quoniam in iugo longiſſime abeſt ab orbis medio centro. </s>
              <s xml:id="echoid-s21870" xml:space="preserve">Est & </s>
              <s xml:id="echoid-s21871" xml:space="preserve">alia in motu diuerſitas: </s>
              <s xml:id="echoid-s21872" xml:space="preserve">nam ſi
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              ſydus ab epicyclo, & </s>
              <s xml:id="echoid-s21873" xml:space="preserve">epicyclus a concentrico feratur, non propterea ceſſaret diuerſitas, quoniam ſydus ab
                <lb/>
              utroque in orientem delatum celerius moueri uideretur, quàm ſi a concentrico ſolo ferretur, & </s>
              <s xml:id="echoid-s21874" xml:space="preserve">in epicyclo aut
                <lb/>
              ſtationem, aut regreſſum faceret. </s>
              <s xml:id="echoid-s21875" xml:space="preserve">nam in contactu earum linearum, quæ a centro ducuntur ad epicyclum, uide
                <lb/>
              tur ſydus quatenus ad epicycli motum pertinet, uidetnr inquam ſtare, ſed in altero circinationis dimidio pro-
                <lb/>
                <note position="left" xlink:label="note-514.01.320-02" xlink:href="note-514.01.320-02a" xml:space="preserve">20</note>
              gredi, & </s>
              <s xml:id="echoid-s21876" xml:space="preserve">in altero regredi. </s>
              <s xml:id="echoid-s21877" xml:space="preserve">Ecce exemplum. </s>
              <s xml:id="echoid-s21878" xml:space="preserve">Currat equus circa maximi circuli ambitum, currentem equum
                <lb/>
              cernat aliquis extra longiſſime ab eo circulo abſens, certe ſiet ut interim uelox, interim tardus, nonnunquã etiã
                <lb/>
              immotus uideatur, ſiet etiam vt interdum progredi, aliàs regredi iudicetur, quamuis æquabili curſu moueatur.
                <lb/>
              </s>
              <s xml:id="echoid-s21879" xml:space="preserve">hoc autem accidit a circuli natura, quæ (ut ait Ariſt. </s>
              <s xml:id="echoid-s21880" xml:space="preserve">in mechan.) </s>
              <s xml:id="echoid-s21881" xml:space="preserve">contrariijs constat. </s>
              <s xml:id="echoid-s21882" xml:space="preserve">Ita ſydus in arcu ſu-
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              periori in earum linearum contactu firmum uidebitur, & </s>
              <s xml:id="echoid-s21883" xml:space="preserve">immotum nobis, qui in imo longe abſentes mora-
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              mur. </s>
              <s xml:id="echoid-s21884" xml:space="preserve">Sed in loco ſummo ingo oppoſito uelociſſime moueri cenſebitur, & </s>
              <s xml:id="echoid-s21885" xml:space="preserve">in ſummo iugo interdum tardius ui-
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              debitur. </s>
              <s xml:id="echoid-s21886" xml:space="preserve">Sed in arcu ſuperno epicycli poſt contactum earum linearum, Sol ſi epicyclum haberet, & </s>
              <s xml:id="echoid-s21887" xml:space="preserve">Luna ab
                <lb/>
              oriente in occidentem defererntur, ſed in arcu inferno a deferente ducerentur. </s>
              <s xml:id="echoid-s21888" xml:space="preserve">Sed alia ſydera contrarios ha-
                <lb/>
              bent motus: </s>
              <s xml:id="echoid-s21889" xml:space="preserve">hinc eſt, quod eorum motus duplici motione conſtat, quarum una eſt epicycli, altera deferentis. </s>
              <s xml:id="echoid-s21890" xml:space="preserve">
                <lb/>
              quod perinde eſt, ac ſi quis a trireme ulterius ducatur, ipſe interim per foros obambularet, unde ſi utraque mo
                <lb/>
                <note position="left" xlink:label="note-514.01.320-03" xlink:href="note-514.01.320-03a" xml:space="preserve">30</note>
              tio ſit orientem uerſus, tunc ſydus duplici motione perlatum uelocius mouebitur, quod non ſecus eſt, ac ſi
                <lb/>
              quis ulterius a trireme delatus, ipſe quoque a puppi ad proram deambulando perueniret. </s>
              <s xml:id="echoid-s21891" xml:space="preserve">Verum ſi planeta
                <lb/>
              contraria latione æquabiliter ſeratur, ita ut quantum una latione progrediatur, tantundem altera regredia-
                <lb/>
              tur, certe ſtare uidebitur, ac ſi quis tantum a prora ad puppim ambularet, quantum ulterius a trireme dela-
                <lb/>
              tus eſſet, ſed ſi inæquales ſunt motiones, celerior uincet: </s>
              <s xml:id="echoid-s21892" xml:space="preserve">unde ſi deferentis motio celerior erit quàm epicycli,
                <lb/>
              ſydus in orientem ferretur, ſi ab epicyclo celerius ducetur, in occidentem delabetur & </s>
              <s xml:id="echoid-s21893" xml:space="preserve">hac ratione regrediens
                <lb/>
              dicetur, ac ſi quis minus regrederetur quàm a trireme ultra delatus foret, uidebitur certe progredi, ſed ſi plus
                <lb/>
              innitatur curſui, regredi uidebitur, unde status & </s>
              <s xml:id="echoid-s21894" xml:space="preserve">regreſſus quinque ſyderibus aduenit in arcu inſeriori epi-
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              cycli, quoniam his locis ab epicylo contra deferentis lationem feruntur. </s>
              <s xml:id="echoid-s21895" xml:space="preserve">Accidit autem aliquibus in locis
                <lb/>
              epicycli motionem parem eſſe, aliqutbus uero uelociorem motione deferentis. </s>
              <s xml:id="echoid-s21896" xml:space="preserve">Sed Soli & </s>
              <s xml:id="echoid-s21897" xml:space="preserve">Lunæ ſtatus, & </s>
              <s xml:id="echoid-s21898" xml:space="preserve">re-
                <lb/>
              greſſus eueniret in arcu ſupremo epicycli, nam eo loco epicyclus contra deferentem nititur, ſed quoniam nec
                <lb/>
                <note position="left" xlink:label="note-514.01.320-04" xlink:href="note-514.01.320-04a" xml:space="preserve">40</note>
              eum uincit, nec illi par eſt, ideo Soli, & </s>
              <s xml:id="echoid-s21899" xml:space="preserve">Lunæ, neque ſtatus, neque regreßus dari ſolet, quod & </s>
              <s xml:id="echoid-s21900" xml:space="preserve">Vitr. </s>
              <s xml:id="echoid-s21901" xml:space="preserve">innuit. </s>
              <s xml:id="echoid-s21902" xml:space="preserve">Soli
                <lb/>
              igitur aut deferens extra centrum, aut epicyclus cum concentrico dabitur. </s>
              <s xml:id="echoid-s21903" xml:space="preserve">nam ſi Sol in cireinatione ſuperna
                <lb/>
              ab oriente, in occidentem fertur, & </s>
              <s xml:id="echoid-s21904" xml:space="preserve">ſi motio epicycli tam ſimilis ſit motioni eccentrici, quàm concentrici, & </s>
              <s xml:id="echoid-s21905" xml:space="preserve">
                <lb/>
              præterea eadem ſit ratio diametri eccentrici ad diametrum concentrici, quæ eſt interualli centrorum ad ſemi-
                <lb/>
              diametrum epicycli, utrum poſueris, conſequetur idem motionis aſpectus. </s>
              <s xml:id="echoid-s21906" xml:space="preserve">Sed quoniam eccentrici modus uni-
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              ca motione contentus eſt, ideo magis adſcitus eſt, quàm modus epicycli. </s>
              <s xml:id="echoid-s21907" xml:space="preserve">Qua uero ratione centrorum inter-
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              ualli, & </s>
              <s xml:id="echoid-s21908" xml:space="preserve">iugi locus deprehenſus eſt, dicam breuiter. </s>
              <s xml:id="echoid-s21909" xml:space="preserve">Quatuor præcipuas partes tanquam puncta in ſignifero
                <lb/>
              ſumpſere, duas equinoctijs, duas ſolſtitijs dedere medijs: </s>
              <s xml:id="echoid-s21910" xml:space="preserve">a motionum, & </s>
              <s xml:id="echoid-s21911" xml:space="preserve">temporum interuallis, centrorum
                <lb/>
              ſpatium, & </s>
              <s xml:id="echoid-s21912" xml:space="preserve">iugi locum percepere. </s>
              <s xml:id="echoid-s21913" xml:space="preserve">Imaginemur lineas duas, ducatur altera a centro deferentis Solis ad Solis
                <lb/>
              centrum, altera æque diſtans ab orbis centro ad ſigniferum, quæ linea medij motus appellatur. </s>
              <s xml:id="echoid-s21914" xml:space="preserve">certum eſt has
                <lb/>
                <note position="left" xlink:label="note-514.01.320-05" xlink:href="note-514.01.320-05a" xml:space="preserve">50</note>
              duas lineas eundem tenorem ſeruaturas, dum in orbem uoluentur. </s>
              <s xml:id="echoid-s21915" xml:space="preserve">Quoniam linea ueri motus est ea, quæ a
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              centro vniuerſi, & </s>
              <s xml:id="echoid-s21916" xml:space="preserve">Solis centrum uſque ad ſigniferum pertingit, & </s>
              <s xml:id="echoid-s21917" xml:space="preserve">arcus interceptus inter lineam ueri, & </s>
              <s xml:id="echoid-s21918" xml:space="preserve">
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              lineam medij motus æquatio Solis dicitur, quæ & </s>
              <s xml:id="echoid-s21919" xml:space="preserve">in iugo, & </s>
              <s xml:id="echoid-s21920" xml:space="preserve">in antiiugo nulla est, utraque enim linea in
                <lb/>
              unam coit. </s>
              <s xml:id="echoid-s21921" xml:space="preserve">ſed in medijs longitudinibus maxima est proportione, ſed in ſignis æque a iugo distantibus æ-
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              quationes æquabiles ſunt, & </s>
              <s xml:id="echoid-s21922" xml:space="preserve">tanto maiores, quanto longitudini mediæ uiciniores habentur. </s>
              <s xml:id="echoid-s21923" xml:space="preserve">Medius ergo
                <lb/>
              motus ab Arietis initio iuxta ſignorum ordinem uſque ad lineam medij motus progreditur, quemadmodum
                <lb/>
              ex eodem loco, & </s>
              <s xml:id="echoid-s21924" xml:space="preserve">uerus motus uſque ad lineam ueri motus defertur. </s>
              <s xml:id="echoid-s21925" xml:space="preserve">unde Solis argumentum, est ſigniferi ar-
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              cus interceptus inter lineam iugi eccentrici iuxta ſignorum ordinem, & </s>
              <s xml:id="echoid-s21926" xml:space="preserve">lineam medij motus, atque ita nomi-
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              natur, quoniam argumentamur ab eo æquationis angulum, quod est, cum in ſemicirculo inferiori linea medij
                <lb/>
                <note position="left" xlink:label="note-514.01.320-06" xlink:href="note-514.01.320-06a" xml:space="preserve">60</note>
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