Newton, Isaac, Philosophia naturalis principia mathematica, 1713

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                  temporibus fieri, jamdudum obſervarunt alii; & accuratiſſime qui­
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                  dem notare licet æqualitatem temporum in Pendulis. </s>
                  <s>Rem tentavi
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                  in Auro, Argento, Plumbo, Vitro, Arena, Sale communi, Ligno,
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                  Aqua, Tritico. </s>
                  <s>Comparabam pyxides duas ligneas rotundas &
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                  æquales. </s>
                  <s>Unam implebam Ligno, & idem Auri pondus ſuſpende­
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                  bam (quam potui exacte) in alterius centro oſcillationis. </s>
                  <s>Pyxides
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                  ab æqualibus pedum undecim filis pendentes, conſtituebant Pen­
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                  dula, quoad pondus, figuram, & acris reſiſtentiam omnino paria:
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                  Et paribus oſcillationibus, juxta poſitæ, ibant una & redibant di­
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                  utiſſime. </s>
                  <s>Proinde copia materiæ in Auro (per Corol. 1. & 6. Prop.
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                  XXIV. Lib. II.) erat ad copiam materiæ in Ligno, ut vis motricis
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                  actio in totum Aurum ad ejuſdem actionem in totum Lignum; hoc
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                  eſt, ut pondus ad pondus. </s>
                  <s>Et ſic in cæteris. </s>
                  <s>In corporibus ejuſ­
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                  dem ponderis differentia materiæ, quæ vel minor eſſet quam pars
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                  milleſima materiæ totius, his experimentis manifeſto deprehendi
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                  potuit. </s>
                  <s>Jam vero naturam gravitatis in Planetas eandem eſſe atque
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                  in Terram, non eſt dubium. </s>
                  <s>Elevari enim fingantur corpora hæc
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                  Terreſtria ad uſque Orbem Lunæ, & una cum Luna motu omni
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                  privata demitti, ut in Terram ſimul cadant; & per jam ante oſtenſa
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                  certum eſt quod temporibus æqualibus deſcribent æqualia ſpatia
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                  cum Luna, adeoque quod ſunt ad quantitatem materiæ in Luna, ut
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                  pondera ſua ad ipſius pondus. </s>
                  <s>Porro quoniam Satellites Jovis
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                  temporibus revolvuntur quæ ſunt in ratione ſeſquiplicata diſtanti­
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                  arum à centro Jovis, erunt eorum gravitates acceleratrices in Jo­
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                  vem reciproce ut quadrata diſtantiarum à centro Jovis; & prop­
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                  terea in æqualibus a Jove diſtantiis, eorum gravitates acceleratrices
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                  evaderent æquales. </s>
                  <s>Proinde temporibus æqualibus ab æqualibus
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                  altitudinibus cadendo, deſcriberent æqualia ſpatia; perinde ut fit
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                  in gravibus, in hac Terra noſtra. </s>
                  <s>Et eodem argumento Planetæ
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                  circumſolares ab æqualibus à Sole diſtantiis demiſſi, deſcenſu ſuo
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                  in Solem æqualibus temporibus æqualia ſpatia deſcriberent. </s>
                  <s>Vires
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                  autem, quibus corpora inæqualia æqualiter accelerantur, ſunt ut
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                  corpora; hoc eſt, pondera ut quantitates materiæ in Planetis.
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                  Porro Jovis & ejus Satellitum pondera in Solem proportionalia
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                  eſſe quantitatibus materiæ eorum, patet ex motu Satellitum quam
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                  maxime regulari; per Corol. 3. Prop. LXV. Lib. I. Nam ſi ho­
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                  rum aliqui magis traherentur in Solem, pro quantitate materiæ
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                  ſuæ, quam cæteri: motus Satellitum (per Corol. 2. Prop. LXV.
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                  Lib. I.) ex inæqualitate attractionis perturbarentur. </s>
                  <s>Si (paribus
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                  à Sole diſtantiis) Satelles aliquis gravior eſſet in Solem pro quan­
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                  </s>
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