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

Table of Notes

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          <p>
            <s xml:id="echoid-s9560" xml:space="preserve">
              <pb o="298" file="314" n="314" rhead="CONSTRUCTION ET USAGES"/>
            de ſon axe tend au Pole inférieur. </s>
            <s xml:id="echoid-s9561" xml:space="preserve">Son oppoſé ſe nomme vertical
              <lb/>
            Septentrional; </s>
            <s xml:id="echoid-s9562" xml:space="preserve">il a le centre en bas, & </s>
            <s xml:id="echoid-s9563" xml:space="preserve">l'extremité de ſon axe tend
              <lb/>
            au Pole ſupérieur du Monde. </s>
            <s xml:id="echoid-s9564" xml:space="preserve">Sa conſtruction eſt la même que cel-
              <lb/>
            le du vertical Méridional; </s>
            <s xml:id="echoid-s9565" xml:space="preserve">car les lignes horaires & </s>
            <s xml:id="echoid-s9566" xml:space="preserve">l'axe font les
              <lb/>
            mêmes angles avec la Meridiene. </s>
            <s xml:id="echoid-s9567" xml:space="preserve">Le Cadran vertical Septentrio-
              <lb/>
            nal ne marque les heures que pendant les grands jours d'Eté; </s>
            <s xml:id="echoid-s9568" xml:space="preserve">ſça-
              <lb/>
            voir, le matin depuis le lever du Soleil juſqu'à ce qu'il paſſe par le
              <lb/>
            premier vertical, & </s>
            <s xml:id="echoid-s9569" xml:space="preserve">le ſoir depuis le tems qu'il repaſſe le premier
              <lb/>
            vertical juſqu'à ſon coucher. </s>
            <s xml:id="echoid-s9570" xml:space="preserve">Quand le Soleil décrit le Tropique
              <lb/>
            d'Eté, il ſe leve ſur l'horiſon de Paris à 4 h. </s>
            <s xml:id="echoid-s9571" xml:space="preserve">& </s>
            <s xml:id="echoid-s9572" xml:space="preserve">joint le premier ver-
              <lb/>
            tical entre 7 & </s>
            <s xml:id="echoid-s9573" xml:space="preserve">8 h. </s>
            <s xml:id="echoid-s9574" xml:space="preserve">du matin; </s>
            <s xml:id="echoid-s9575" xml:space="preserve">l'après midi il repaſſe par le premier
              <lb/>
            vertical entre 4 & </s>
            <s xml:id="echoid-s9576" xml:space="preserve">5 h. </s>
            <s xml:id="echoid-s9577" xml:space="preserve">du ſoir & </s>
            <s xml:id="echoid-s9578" xml:space="preserve">ſe couche à 8, c'eſt pourquoi on
              <lb/>
            marque ſur ce Cadran les heures depuis 4 h. </s>
            <s xml:id="echoid-s9579" xml:space="preserve">du matin juſqu'à 8,
              <lb/>
            & </s>
            <s xml:id="echoid-s9580" xml:space="preserve">depuis 4 h. </s>
            <s xml:id="echoid-s9581" xml:space="preserve">du ſoir juſqu'à 8.</s>
            <s xml:id="echoid-s9582" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s9583" xml:space="preserve">En ce tems-là le vertical Méridional n'eſt éclairé que depuis en-
              <lb/>
            viron 8 h. </s>
            <s xml:id="echoid-s9584" xml:space="preserve">du matin juſqu'à 4 h. </s>
            <s xml:id="echoid-s9585" xml:space="preserve">du ſoir.</s>
            <s xml:id="echoid-s9586" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s9587" xml:space="preserve">Mais quand le Soleil par ſon mouvement annuel a rejoint l'E-
              <lb/>
            quateur, il ne marque plus les heures ſur le vertical Septentrional,
              <lb/>
            & </s>
            <s xml:id="echoid-s9588" xml:space="preserve">il les marque ſur ſon oppoſé dépuis ſon lever juſqu'à ſon coucher.</s>
            <s xml:id="echoid-s9589" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div617" type="section" level="1" n="313">
          <head xml:id="echoid-head446" style="it" xml:space="preserve">Conſtruction du Cadran Polaire.</head>
          <p>
            <s xml:id="echoid-s9590" xml:space="preserve">L A figure 6 repreſente un Polaire ſupérieur. </s>
            <s xml:id="echoid-s9591" xml:space="preserve">C'eſt un Cadran
              <lb/>
            incliné vers le Cicl, mais qui ne decline point, car il eſt parallele
              <lb/>
            à l'axe du Monde & </s>
            <s xml:id="echoid-s9592" xml:space="preserve">au cercle de 6 h. </s>
            <s xml:id="echoid-s9593" xml:space="preserve">qui coupe le Méridien à an-
              <lb/>
            gles droits. </s>
            <s xml:id="echoid-s9594" xml:space="preserve">C'eſt pour quoi il ne peut jamais marquer 6 h. </s>
            <s xml:id="echoid-s9595" xml:space="preserve">du ma-
              <lb/>
            tin ou du ſoir, parce que pour lors l'ombre du Style étant parallele
              <lb/>
            au plan du Cadran, il n'y peut pas faire ombre.</s>
            <s xml:id="echoid-s9596" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s9597" xml:space="preserve">Ce Cadran n'a point de centre & </s>
            <s xml:id="echoid-s9598" xml:space="preserve">les heures ſont parralleles entr'-
              <lb/>
            elles & </s>
            <s xml:id="echoid-s9599" xml:space="preserve">à l'axe du Monde. </s>
            <s xml:id="echoid-s9600" xml:space="preserve">Son plan étant parallele à un horiſon de
              <lb/>
            la Sphere droite, paſſe parles deux Poles du Monde, d'où il tire ſon
              <lb/>
            nom de Polaire.</s>
            <s xml:id="echoid-s9601" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s9602" xml:space="preserve">Pour le tracer tirez premierement la ligne AB, repreſentant l'é-
              <lb/>
              <note position="left" xlink:label="note-314-01" xlink:href="note-314-01a" xml:space="preserve">Fig. 6.</note>
            quinoxiale, & </s>
            <s xml:id="echoid-s9603" xml:space="preserve">ID à l'équerre, pour la Méridienne ou ligne de 12 h.
              <lb/>
            </s>
            <s xml:id="echoid-s9604" xml:space="preserve">prenez la longueur du ſtyle à diſcretion, ſuivant la grandeur du plan
              <lb/>
            comme ici CD; </s>
            <s xml:id="echoid-s9605" xml:space="preserve">de ſon extremité D faites un quart de cercle que
              <lb/>
            vous diviſerez en 6 arcs égaux ou ſeulement un arc de 60 deg. </s>
            <s xml:id="echoid-s9606" xml:space="preserve">que
              <lb/>
            vous diviſerezen 4 de 15 d. </s>
            <s xml:id="echoid-s9607" xml:space="preserve">chacun pour les 4 premieres heures a-
              <lb/>
            près midi, & </s>
            <s xml:id="echoid-s9608" xml:space="preserve">ajoûtezenſuite un pareil arc de 15 d. </s>
            <s xml:id="echoid-s9609" xml:space="preserve">pour la 5
              <emph style="sub">me</emph>
            h. </s>
            <s xml:id="echoid-s9610" xml:space="preserve">du
              <lb/>
            point D, tirez des lignes ponctuées depuis les diviſions de la circon-
              <lb/>
            ference dudit arc, juſqu'au rencontre de la ligne AB; </s>
            <s xml:id="echoid-s9611" xml:space="preserve">& </s>
            <s xml:id="echoid-s9612" xml:space="preserve">par ces
              <lb/>
            points de rencontre tracez les lignes horaires paralleles à la Méri-
              <lb/>
            </s>
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