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

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              <s>
                <pb xlink:href="020/01/313.jpg" pagenum="294"/>
              dasse calzante, poi il medesimo postovi riscaldato vi giocasse.... Dubito che
                <lb/>
              l'effetto possa venir da altra cagione. </s>
              <s>Pare che sia cosa certa che un chia­
                <lb/>
              vistello di ferro giochi meno ne'suoi occhi pure di ferro, secondo che l'aria
                <lb/>
              si ritruova di tale e tale costituzione ” (MSS Cim. </s>
              <s>T. XXIV, c. </s>
              <s>12). </s>
            </p>
            <p type="main">
              <s>Ma il Viviani, ben persuaso della peripatetica caponaggine del Rinal­
                <lb/>
              dini, e aspettandosi che, come aveva già fatto perdere la pazienza a quello
                <lb/>
              stizzoso del Borelli volesse seguitar a mettere a più duro cimento la sua,
                <lb/>
              si studiava di persuader colle seguenti parole l'amico e il collega della ve­
                <lb/>
              rità delle ragioni e dei fatti osservati intorno alla virtù che ha il calore di
                <lb/>
              dilatare i corpi: “ Il dubbio di V. S. E. fondato sull'effetto del chiavistello,
                <lb/>
              veramente mi giunge nuovo, perchè mi credevo che, per dimostrare l'al­
                <lb/>
              largamento e stringimento del vaso, mediante il caldo e il freddo, non si po­
                <lb/>
              tesse far più che trovar modo di toccarlo con mano, come ultimamente ci
                <lb/>
              ha fatto osservare S. A. S. per mezzo di quell'anima di metallo applicata
                <lb/>
              dentro l'anello pur di metallo ora caldo ed ora freddo. </s>
              <s>Se dunque il senso
                <lb/>
              del tatto non gli par giusto giudice, giacchè ella attribuisce l'effetto del me­
                <lb/>
              glio giocar del maschio nell'anello riscaldato, all'attenuazione dell'aria in­
                <lb/>
              clusa tra l'uno e l'altro cagionata dal calor dell'anello; consideri di grazia
                <lb/>
              V. S. se gli par di prestar più fede ad alcuno degli altri sensi.... Io ho
                <lb/>
              tese all'unisono due corde di rame di ugual lunghezza e giustezza .... ed
                <lb/>
              assai distanti fra loro, sotto una delle quali ho rappresentato un caldanuzzo
                <lb/>
              con poco fuoco per riscaldarla, e toccata l'una e l'altra nel medesimo tempo,
                <lb/>
              ho sempre osservato, insieme con molti altri ai quali ho conferita questa
                <lb/>
              esperienza, che la corda riscaldata ingravisce notabilmente di suono....
                <lb/>
              Quanto poi al senso della vista, ho preso un filo o corda di rame delle più
                <lb/>
              grosse da clavicembalo ben ricotta .... e ad una delle sue estremità ho at­
                <lb/>
              taccata una palla di piombo .... e, formato così un pendolo, sotto alla palla
                <lb/>
              ho accomodato una lastra di vetro distante la grossezza di un testone. </s>
              <s>Ho
                <lb/>
              di poi, mentre tal pendolo stava fermo, o quando aveva poco moto, acco­
                <lb/>
              stata la fiamma d'un moccolino al fil di rame, scorrendo in giù e in su
                <lb/>
              colla mano, e ho mille volte osservato e veduto patentemente che appena
                <lb/>
              riscaldato il filo la palla arrivava a toccare il vetro, e rimossa la fiammella
                <lb/>
              tornava immediatamente a discostarsene all'altezza di prima.... Per la qual
                <lb/>
              dimostrazione (dell'effetto dell'introduzione de'calidi) mi sarei persuaso che
                <lb/>
              il solo e semplice effetto di veder, nell'atto dell'immersione della boccia
                <lb/>
              nell'acqua calda, abbassar giù per il collo l'acqua inclusa, e per il contra­
                <lb/>
              rio alzar per l'immersione della medesima boccia nell'acqua fredda;....
                <lb/>
              fosse stata prova bastante.... Ma già parmi che omai si possa concludere
                <lb/>
              il signor Borelli avere intorno a questo effetto ottimamente discorso ” (MSS.
                <lb/>
              Gal. </s>
              <s>Dis. </s>
              <s>T. CXLII, c. </s>
              <s>31, 32). </s>
            </p>
            <p type="main">
              <s>Le due esperienze descritte qui dal Viviani si trasformarono in quel­
                <lb/>
              l'altre due, che si leggon nel libro de'
                <emph type="italics"/>
              Saggi
                <emph.end type="italics"/>
              a pag. </s>
              <s>122, 23 della citata
                <lb/>
              edizione. </s>
              <s>Ma l'esperienza della palla pendula, che in sostanza è quella fatta
                <lb/>
              parecchi anni prima dall'Aggiunti, fu dal Viviani stesso resa più evidente, </s>
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