Bernstein, Aaron, Naturwissenschaftliche Volksbücher, Bd. 1/5, 1897

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            <s xml:id="echoid-s674" xml:space="preserve">
              <pb o="48" file="058" n="58"/>
            Kompaß. </s>
            <s xml:id="echoid-s675" xml:space="preserve">Nun brachte er an beiden Enden der Stahlſtange
              <lb/>
            zwei kleine Kugeln aus Metall an, die gleich ſchwer waren,
              <lb/>
            wodurch die Stahlſtange auf jeder Seite gleich ſtark von der
              <lb/>
            Erde angezogen wurde und daher immer wagerecht liegen
              <lb/>
            blieb, wie der Balken einer Wage, wenn gleiche Gewichte in
              <lb/>
            den Schalen liegen. </s>
            <s xml:id="echoid-s676" xml:space="preserve">Dadurch wurde zwar die Anziehungskraft
              <lb/>
            der Erde nicht aufgehoben, aber ſie wurde durch die Gleichheit
              <lb/>
            der Gewichte ausgeglichen und alſo für ſeinen Apparat un-
              <lb/>
            wirkſam.</s>
            <s xml:id="echoid-s677" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s678" xml:space="preserve">Nunmehr ſtellte er zwei große, ſehr ſchwere Metallkugeln
              <lb/>
            ſo zu beiden Seiten der Stahlſtange auf, daß die kleinen
              <lb/>
            Kugeln an der Stange ihnen ſehr nahe waren, ohne ſie jedoch
              <lb/>
            zu berühren. </s>
            <s xml:id="echoid-s679" xml:space="preserve">Die Anziehungskraft der großen Kugeln begann
              <lb/>
            nun zu wirken und zog die kleinen Kugeln ſo an, daß ſie in
              <lb/>
            der nächſten Nähe der großen Kugeln ruhen blieben. </s>
            <s xml:id="echoid-s680" xml:space="preserve">Wenn
              <lb/>
            der Beobachter nun durch einen leiſen Stoß die kleinen Kugeln
              <lb/>
            von ihrem Ruhepunkt entfernte, ſo zogen die großen Kugeln die
              <lb/>
            kleinen wieder zurück; </s>
            <s xml:id="echoid-s681" xml:space="preserve">aber da ſie im Lauf nicht inne halten
              <lb/>
            konnten, gingen ſie über den Ruhepunkt hinaus, wurden dann
              <lb/>
            wiederum zurück angezogen und begannen ebenſo gegen die
              <lb/>
            großen Kugeln zu pendeln, wie ein Pendel es thut, wenn die
              <lb/>
            Erde darauf die Anziehungskraft ausübt. </s>
            <s xml:id="echoid-s682" xml:space="preserve">Freilich war dieſe
              <lb/>
            Anziehungskraft außerordentlich ſchwach gegen die der Erde
              <lb/>
            und deshalb war auch die Schwingung dieſes Pendels bei
              <lb/>
            weitem langſamer, als die des gewöhnlichen Pendels; </s>
            <s xml:id="echoid-s683" xml:space="preserve">aber
              <lb/>
            gerade dies mußte auch ſein, und aus der Langſamkeit der
              <lb/>
            Schwingung oder aus der geringen Zahl der Schwingungen
              <lb/>
            im Verlauf eines Tages berechnete Cavendiſh das wirkliche
              <lb/>
            Gewicht der Erde.</s>
            <s xml:id="echoid-s684" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s685" xml:space="preserve">Allein ſolch ein Verſuch iſt mit außerordentlichen Schwierig-
              <lb/>
            keiten verbunden, denn auch nur die leiſeſte Ausdehnung der
              <lb/>
            Kugeln oder der Stange durch die Wärme ändert das Reſultat,
              <lb/>
            auch mußte er in einem Raume vorgenommen werden, wo </s>
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