Bion, Nicolas, Traité de la construction et principaux usages des instruments de mathématique, 1723

Table of Notes

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            <s xml:id="echoid-s11521" xml:space="preserve">
              <pb o="353" file="369" n="369" rhead="DES CADRANS AU SOLEIL. Liv. VIII. Ch. II."/>
            tous ces points vous tracerez la ligne horaire courbe de 10 h. </s>
            <s xml:id="echoid-s11522" xml:space="preserve">du
              <lb/>
            matin, & </s>
            <s xml:id="echoid-s11523" xml:space="preserve">de 2 h. </s>
            <s xml:id="echoid-s11524" xml:space="preserve">apres midi.</s>
            <s xml:id="echoid-s11525" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s11526" xml:space="preserve">Vous en ferez de même pour toutes les autres lignes horaires;
              <lb/>
            </s>
            <s xml:id="echoid-s11527" xml:space="preserve">vous joindrez le mieux qu'il vous ſera poſſible, par des lignes cour-
              <lb/>
            bes, tous les points qui appartiennent à une même heure, & </s>
            <s xml:id="echoid-s11528" xml:space="preserve">mar-
              <lb/>
            querez les caracteres des Signes & </s>
            <s xml:id="echoid-s11529" xml:space="preserve">les premieres Lettres des mois,
              <lb/>
            comme auſſi les chifres des heures, chacun en leur place, comme la
              <lb/>
            figure le montre, & </s>
            <s xml:id="echoid-s11530" xml:space="preserve">le Cadran ſera achevé.</s>
            <s xml:id="echoid-s11531" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s11532" xml:space="preserve">Vous contournerez enſuite ce Parallelograme autour du Cylin-
              <lb/>
            dre, enſorte que les lignes qui repreſentent les deux Tropiques,
              <lb/>
            ſoient bien paralleles entr'elles. </s>
            <s xml:id="echoid-s11533" xml:space="preserve">On peut tracer de même les Signes
              <lb/>
            & </s>
            <s xml:id="echoid-s11534" xml:space="preserve">les heures ſur les corps mêmes des Cylindres.</s>
            <s xml:id="echoid-s11535" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s11536" xml:space="preserve">Le ſtyle eſt attaché à un chapiteau qui ſert d'ornement, & </s>
            <s xml:id="echoid-s11537" xml:space="preserve">doit
              <lb/>
            être d'équerre & </s>
            <s xml:id="echoid-s11538" xml:space="preserve">mobile ſur la ligne A B, afin de pouvoir le placer
              <lb/>
            ſur le degré du Signe ou le jour du mois courant. </s>
            <s xml:id="echoid-s11539" xml:space="preserve">Ce Cadran étant
              <lb/>
            poſé perpendiculairement ou ſuſpendu par un anneau, tournez-lc
              <lb/>
            vis-à-vis le Soleil, juſqu'à ce que l'ombre du ſtyle tombe à plomb
              <lb/>
            ſur le parallele du jour; </s>
            <s xml:id="echoid-s11540" xml:space="preserve">ſon extremité marquera l'heure, ou partie
              <lb/>
            d'heure preſente.</s>
            <s xml:id="echoid-s11541" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s11542" xml:space="preserve">On peut encore par cet Inſtrument connoître à toute heure la
              <lb/>
            hauteur du Soleil. </s>
            <s xml:id="echoid-s11543" xml:space="preserve">Pour cet effet poſez le ſtyle ſur l'échelle des hau-
              <lb/>
            teurs, tenez le Cylindre ſuspendu ou placé horiſontalement, tour-
              <lb/>
            nez-le de ſorte que le ſtyle ſoit vers le Soleil, pour lors l'extremité de
              <lb/>
            ſon ombre perpendiculaire marquera la hauteur du Soleil ſur l'ho-
              <lb/>
            riſon.</s>
            <s xml:id="echoid-s11544" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s11545" xml:space="preserve">Ce Parallelograme peut ſervir auſſi de Cadran, ſans être contour-
              <lb/>
              <note position="right" xlink:label="note-369-01" xlink:href="note-369-01a" xml:space="preserve">Fig. 3.</note>
            né ſur un Cylindre, en ajuſtant le ſtyle de maniere qu'il puiſſe cou-
              <lb/>
            ler au long de la ligne AB, & </s>
            <s xml:id="echoid-s11546" xml:space="preserve">s'arrêter ſur le parallele du Signe ou
              <lb/>
            du jour du mois. </s>
            <s xml:id="echoid-s11547" xml:space="preserve">Il n'y a qu'à faire une petite fente au haut de la
              <lb/>
            Platine, & </s>
            <s xml:id="echoid-s11548" xml:space="preserve">applatir le pied du ſtyle de telle ſorte qu'il puiſſe couler
              <lb/>
            dans cette fente ſans changer de longueur.</s>
            <s xml:id="echoid-s11549" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s11550" xml:space="preserve">Pour s'en ſervir il faut que ſon Plan ſoit bien perpendiculaire & </s>
            <s xml:id="echoid-s11551" xml:space="preserve">
              <lb/>
            la ligne AB de niveau, ce que l'on fait aiſement par le moyen d'un
              <lb/>
            petit plomb dont la ſoie eſt attachée ſur un côté de la Platine. </s>
            <s xml:id="echoid-s11552" xml:space="preserve">Le
              <lb/>
            tenant ainſi d'une main, ou ſuſpendu par un anneau, on l'expoſe
              <lb/>
            directement au Soleil, de telle ſorte que l'ombre du ſtyle ſoit étenduë
              <lb/>
            ſur la ligne qui repreſente le parallele du Signe ou du mois, & </s>
            <s xml:id="echoid-s11553" xml:space="preserve">ſon
              <lb/>
            extremité marquera l'heure.</s>
            <s xml:id="echoid-s11554" xml:space="preserve"/>
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