Caverni, Raffaello, Storia del metodo sperimentale in Italia, 1891-1900

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                <pb xlink:href="020/01/1949.jpg" pagenum="192"/>
              del perpendicolo, “ et quoniam AG horizzonti non est perpendicularis, ma­
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              gnitudo ex ponderibus E, H composita in hoc situ minime persistet, sed
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              deorsum, secundum eius centrum gravitatis G, per circumferentiam GD mo­
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              vebitur, donec AG horizonti fiat perpendicularis, scilicet donec AG in AD
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              redeat ” (Mechanic. </s>
              <s>lib., Pisauri 1677, fol. </s>
              <s>4). La nuova dimostrazione, mo­
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              vendo da principii più sicuri, è più propria di quella di Aristotile e più pre­
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              cisa, perchè, mentre la ragion del Filosofo si faceva principalmente dipen­
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              dere dal peso delle braccia della Bilancia, quella di Guidubaldo astrae da
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              questa material condizione, ed è perciò applicabile al caso, in cui secondo
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              gl'istituti archimedei si considerino i pesi sostenuti da leve imponderabili. </s>
            </p>
            <p type="main">
              <s>Quanto al secondo caso della detta Question meccanica lo stesso Gui­
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              dubaldo, nella proposizione sua III, sempre scorto da quella fida regola ba­
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              ricentrica, corregge il gravissimo errore di Aristotile, inconsideratamente ri­
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              petuto, come udimmo, dal Tartaglia: e perciocchè, rimossa la Bilancia in OR,
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              nell'antecedente figura LXXXI, il centro di gravità s'è dovuto trasferire in
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              G, e GM perciò non più riesce perpendicolare all'orizzonte “ magnitudo,
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              dunque di qui ne conclude, ex O, R ponderibus composita, in hoc situ
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              mi­
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              nime manebit,
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              sed secundum eius gravitatis centrum G deorsum per cir­
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              cumferentiam GH movebitur ” (ibid., fol. </s>
              <s>5). </s>
            </p>
            <p type="main">
              <s>È ora una così fatta conclusione manifestamente contraria a quella di
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              Aristotile, il quale aveva detto nel sopra allegato testo che, rimossa la Bi­
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              lancia dal sito suo orizzontale, ivi
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              necesse est manere.
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              Notabile è a questo
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              proposito che Guidubaldo, invece di reclamare contro l'errore scoperto, si
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              lusinghi di ridurre i falsi sensi del Filosofo alle più chiare espressioni del
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              vero. </s>
              <s>“ Aristotelis quoque ratio hic perspicua erit: si enim punctum D (nella
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              preposta figura LXXXI) ubi OR, DM se invicem secant; erit DO maior DR,
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              et quoniam DM perpendiculum, secundum ipsum Aristotilem, Libram OR
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              in partes inaequales dividit, et maior pars est versus O, hoc est DO: Libra
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              OR ex parte O deorsum movebitur, cum id quod plus est deorsum fera­
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              tur ” (ibid., fol. </s>
              <s>25 ad t.). </s>
            </p>
            <p type="main">
              <s>Si può facilmente concedere, supposto che la ponderosità della Bilancia
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              resulti non da'pesi soli ma e dalle braccia, che la ragion di Aristotile sia
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              da questo commento resa fin qui perspicua: ma quel che segue benchè
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              Guidubaldo non faccia vista, e non sospetti che se n'abbiano ad avvedere i
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              sagaci lettori, la rende apertamente contradittoria, perchè mentre là nelle
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              Questioni meccaniche si diceva che, rimosso in O (nella passata fig. </s>
              <s>LXXXI)
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              lo strumento,
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              necesse est ibi manere,
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              qui, nel libro
                <emph type="italics"/>
              Mechanicorum,
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              si sog­
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              giunge così, descrivendo con tutta la più desiderabile precisione le condi­
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              zioni e gli effetti degl'instabili equilibrii: “ Similiter ex dictis quoque eli­
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              ciemus Libram OR, centrum habens infra libram, quo magis a situ CN
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              distabit velocius moveri. </s>
              <s>Centrum enim gravitatis G, quo magis a puncto D
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              distat, eo velocius pondus ex O, R ponderibus Libraque OR compositum
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              movebitur, donec angulus CGO rectus evadat: adhuc insuper velocius mo­
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              vebitur quo Libram a centro D magis distabit ” (ibid.). </s>
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