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

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            <p type="main">
              <s>
                <pb xlink:href="020/01/342.jpg" pagenum="323"/>
              in qual genere di curva dee inflettersi la lamina AB perchè la palla, disten­
                <lb/>
              dendosi il filo, descriva l'apotema del conoide isocrono? </s>
              <s>E trovò che quella
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              lamina dovea esser piegata in figura di parabola, che è l'evoluta da cui si
                <lb/>
              descrive per evoluzione la curva genitrice di quello stesso conoide. </s>
            </p>
            <p type="main">
              <s>Avviate per questa nuova luminosa via le idee, tutta la difficoltà del­
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              l'applicare il pendolo cicloidale consisteva in trovare qual dovesse essere
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              l'evoluta, dall'evoluzione della quale si descrivesse una Cicloide. </s>
              <s>Suppon­
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              gasi infatti che sia AB (fig. </s>
              <s>22) questa evoluta configurata in lamina me­
                <lb/>
              tallica e che sia alla sommità di lei appeso il filo pendulo AC. </s>
              <s>Nel salire
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              da C verso D avvolgendosi alla lamina, e nello scendere da D verso C svol­
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              gendosi dalla medesima, si descriverà dall'estremità di quel filo una mezza
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                <figure id="id.020.01.342.1.jpg" xlink:href="020/01/342/1.jpg" number="30"/>
              </s>
            </p>
            <p type="caption">
              <s>Figura 22.
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              Cicloide o un mezzo arco di Cicloide. </s>
              <s>Che se si
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              assetti un'altra lamina uguale, dall'altra parte AE,
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              il filo stesso col peso, ricaduto da D, nel risalire
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              in F descriverà un altro arco di Cicloide, cosicchè
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              tutta la curva DCF descritta dal pendolo sarà ci­
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              cloidale, e perciò isocrona da qualunque punto ri­
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              salga il peso C e da qualunque altro punto di­
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              scenda. </s>
              <s>Or la Geometria rivelò all'Huyghens che le
                <lb/>
              due lamine AB, AE, perchè riuscissero a dare il
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              desiderato isocronismo, dovevano essere configu­
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              rate in semicicloide, conforme al Teorema da lui
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              dimostrato, nella proposiz. </s>
              <s>VI della Parte III del­
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              l'Orologio Oscillatorio, che cioè la curva descritta per evoluzione da un'emi­
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              cicloide è un'altra emicicloide uguale e simile all'evoluta. </s>
            </p>
            <p type="main">
              <s>Tale è il macchinamento che l'Huyghens venne applicando, colla ferma
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              speranza di aver dato così la massima perfezione all'Orologio. </s>
              <s>Una verga
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              metallica raccomandata alla solida armatura della macchina sostiene le due
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              laminette piegate in figura di semicicloide, in mezzo alle quali pende il filo
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              flessibile, a cui è raccomandata la verghetta metallica del pendolo. </s>
              <s>Questa
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              stessa verghetta passa attraverso al foro della clavicola fissata all'estremità
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              dello scappamento a serpe, che gioca con le sue alette in posizione oriz­
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              zontale, fra le tacche della ruota a denti di sega, precisamente come nel
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              Cronoscopio descrittoci dal Sinclaro. </s>
            </p>
            <p type="main">
              <s>La descrizione di questo nuovo Misuratore del tempo, insiem coi Teo­
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              remi concernenti la caduta de'gravi per gli archi di Cicloide, e le Evolute,
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              e i Centri di oscillazione, e le Forze centrifughe furono pubblicati nel 1673
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              in Parigi, in quell'Opera immortale che s'intitola
                <emph type="italics"/>
              Orologium oscillatorium.
                <emph.end type="italics"/>
                <lb/>
              E ora è questa stessa pubblicazione, che ravvia la nostra Storia in Italia. </s>
            </p>
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