Newton, Isaac, Philosophia naturalis principia mathematica, 1713

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      <text>
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              <s>
                <pb xlink:href="039/01/031.jpg" pagenum="3"/>
              actus, a circumagente manu abire conatur; & conatu ſuo fundam
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              diſtendit,
                <expan abbr="eoq;">eoque</expan>
              fortius quo celerius revolvitur; &, quamprimum di­
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              mittitur, avolat. </s>
              <s>Vim conatui illi contrariam, qua funda lapidem
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              in manum perpetuò retrahit & in orbe retinet, quoniam in manum
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              ceu orbis centrum dirigitur, Centripetam appello. </s>
              <s>Et par eſt ratio
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              corporum omnium, quæ in gyrum aguntur. </s>
              <s>Conantur ea omnia a
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              centris orbium recedere; & niſi adſit vis aliqua conatui iſti contra­
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              ria, qua cohibeantur & in orbibus retineantur, quamQ.E.I.eò Centri­
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              petam appello, abibunt in rectis lineis uniformi cum motu. </s>
              <s>Pro­
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              jectile, ſi vi Gravitatis deſtitueretur, non deflecteretur in terram, ſed
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              in linea recta abiret in cælos; idque uniformi cum motu, ſi modo
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              aeris reſiſtentia tolleretur. </s>
              <s>Per gravitatem ſuam retrahitur a curſu
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              rectilineo & in terram perpetuo flectitur, idque magis vel minus
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              pro gravitate ſua & velocitate motus. </s>
              <s>Quo minor erit ejus gravitas pro quantitate materiæ vel major &c. </s>
              <s>
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              vel major velocitas quacum projicitur, eo minus deviabit a curſu
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              rectilineo & longius perget. </s>
              <s>Si Globus plumbeus, data cum velo­
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              citate ſecundum lineam horizontalem a montis alicujus vertice vi
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              pulveris tormentarii projectus, pergeret in linea curva ad diſtantiam
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              duorum milliarium, priuſquam in terram decideret: hic dupla cum
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              velocitate quaſi duplo longius pergeret, & decupla cum velocitate
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              quaſi decuplo longius: ſi modo aeris reſiſtentia tolleretur. </s>
              <s>Et augendo
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              velocitatem augeri poſſet pro lubitu diſtantia in quam projiceretur,
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              & minui curvatura lineæ quam deſcriberet, ita ut tandem caderet
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              ad diſtantiam graduum decem vel triginta vel nonaginta; vel etiam
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              ut terram totam circuiret priuſquam caderet; vel denique ut in
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              terram nunquam caderet, ſed in cælos abiret & motu abeundi per­
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              geret in infinitum. </s>
              <s>Et eadem ratione, qua Projectile vi gravitatis
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              in orbem flecti poſſet & terram totam circuire, poteſt & Luna vel
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              vi gravitatis, ſi modo gravis ſit, vel alia quacunque vi, qua in ter­
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              ram urgeatur, retrahi ſemper a curſu rectilineo terram verſus, &
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              in orbem ſuum flecti: & abſque tali vi Luna in orbe ſuo retineri
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              non poteſt. </s>
              <s>Hæc vis, ſi juſto minor eſſet, non ſatis flecteret Lunam
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              de curſu rectilineo: ſi juſto major, plus ſatis flecteret, ac de orbe
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              terram verſus deduceret. </s>
              <s>Requiritur quippe, ut ſit juſtæ magnitudinis:
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              & Mathematieorum eſt invenire Vim, qua corpus in dato quovis
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              orbe data cum velocitate accurate retineri poſſit; & viciſſim inve­
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              nire Viam curvilineam, in quam corpus e dato quovis loco data
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              cum velocitate egreſſum a data vi flectatur. </s>
              <s>Eſt autem vis hujus cen­
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              tripetæ Quantitas trium generum, Abſoluta, Acceleratrix, & Motrix. </s>
            </p>
          </chap>
        </body>
      </text>
    </archimedes>
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