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

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            <p type="main">
              <s>
                <pb xlink:href="020/01/2090.jpg" pagenum="333"/>
              tali BC, tempus per AB, ad tempus per AC, est ut AB ad AC. </s>
              <s>Ergo eadem
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                <figure id="id.020.01.2090.1.jpg" xlink:href="020/01/2090/1.jpg" number="347"/>
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            </p>
            <p type="caption">
              <s>Figura 156.
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              momenta velocitatis per AB et per AC: est enim una ca­
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              demque velocitas illa, quae, temporibus inaequalibus, spa­
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              cia transit inaequalia eamdem quam tempora rationem ha­
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              bentia ” (MSS. Gal., P. V, T. II, fol. </s>
              <s>164 a tergo). </s>
            </p>
            <p type="main">
              <s>Il teorema fondamentale dei tempi proporzionali agli
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              spazi nella verticale e nell'obliqua ugualmente elevate, è qui
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              come là concluso dallo stesso supposto principio, ma ne'dia­
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              loghi Del mondo è la supposizione, messa per fondamento ai
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              dialoghi Del moto, fatta dipendere da un'altra supposizione,
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              tolta la quale, rovinerebbe necessariamente ogni scienza dei
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              moti naturali e dei proietti. </s>
              <s>Abbiamo poco fa udito consi­
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              stere una tal supposizione nell'ammetter che l'impeto della
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              scesa sia bastante a far risalire il mobile alla medesima al­
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              tezza, di che dà Galileo, a varie occasioni, nelle varie sue
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              Opere, tal dimostrazione, da non si mettere in dubbio per
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                <figure id="id.020.01.2090.2.jpg" xlink:href="020/01/2090/2.jpg" number="348"/>
              </s>
            </p>
            <p type="caption">
              <s>Figura 157.
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              nessuno, che specialmente gli abbia concesso esser nei
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              moti accelerati le velocità proporzionali ai tempi. </s>
              <s>In quel
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              discorso infatti, trascritto a pag. </s>
              <s>307 nel capitolo addietro,
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              si sovverranno i Lettori come, dal suppor
                <emph type="italics"/>
              che il grave
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              cadente naturalmente vada continuamente accrescendo
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              la sua velocità, secondo che accresce la distanza dal
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              termine onde si partì,
                <emph.end type="italics"/>
              se ne concludesse che il mobile
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              in C, in D, in E (fig. </s>
              <s>157) e negli altri infiniti punti
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              della linea AB, ha per la caduta acquistato tale impeto,
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              da ricondursi in A al suo primo principio. </s>
            </p>
            <p type="main">
              <s>Sperava Galileo di poter forse dimostrare quel suo
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              supposto, da cui diceva conseguir questo effetto, ma la
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              sua dimostrazione, che cioè si velocitino i gravi proporzio­
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              natamente ai tempi, rimase per l'Autore e per noi un desiderio, non so­
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              disfatto che in parte e indirettamente dagli Accademici del Cimento, i quali
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              narrano di aver fatto una tale esperienza: “ Una pallina di vetro piena,
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              lasciata dall'altezza di 50 parti, arrivò con la riflessione maggiore a gradi
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              48, mancandoli, per arrivare d'ond'ella partissi dalla quiete, due gradi soli,
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              che potevano importare un soldo in circa del nostro braccio a panno fio­
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              rentino. </s>
              <s>Da questa esperienza vien quasi confermata la conclusione del Ga­
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              lileo, che un grave, nell'infimo termine della sua scesa, abbia acquistato tan­
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              t'impeto, che basti a ricondurlo alla medesima orizzontale, dove egli principiò
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              suo moto, potendo probabilmente dirsi che l'impedimento del mezzo, come
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              il medesimo Galileo dice seguire nei pendoli, ed il cedere, benchè pochissimo,
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              del grave cadente e del piano, ov'egli venne a riflettersi; abbian dato mo­
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              tivo alla detta palla, e sieno stati causa che ella non si riduca con la rifles­
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              sione precisamente alla medesima altezza di parti 50. ” (Targioni, Notizie
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              delle scienze fisiche in Toscana, T. II, P. II, Firenze 1780, pag. </s>
              <s>667, 68). </s>
            </p>
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