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-s1309" xml:space="preserve">
              <pb o="30" file="044" n="44" rhead="CONSTRUCTION ET USAGES"/>
            droite ladite regle, & </s>
            <s xml:id="echoid-s1310" xml:space="preserve">c'eſt ainſi qu'on met le compas de proportion
              <lb/>
            au centre; </s>
            <s xml:id="echoid-s1311" xml:space="preserve">l'autre regle étant auſſi dreſſée en dedans, & </s>
            <s xml:id="echoid-s1312" xml:space="preserve">fen-
              <lb/>
            duë pour recevoir le ſimple de la charniere, on creuſe le bout en de-
              <lb/>
            mi cercle concave, de maniere qu'il joigne bien autour de la tête,
              <lb/>
            puis on rive le ſimple à cette regle avcc trois ou quatre petits clous,
              <lb/>
            afin que ces deux regles, que l'on nomme les jambes du compas de
              <lb/>
            proportion, ſe puiſſent ouvrir & </s>
            <s xml:id="echoid-s1313" xml:space="preserve">fermer facilement, & </s>
            <s xml:id="echoid-s1314" xml:space="preserve">reſter a telle
              <lb/>
            ouverture que l'on peut en avoir beſoin pour mettre les uſages en
              <lb/>
            pratique. </s>
            <s xml:id="echoid-s1315" xml:space="preserve">Mais il faut avoir bien ſoin, en le conſtruiſant, que les
              <lb/>
            jambes ſoient limées bien plates, & </s>
            <s xml:id="echoid-s1316" xml:space="preserve">ne faſſent pas ce qu'on appelle
              <lb/>
            l'aîle de moulin. </s>
            <s xml:id="echoid-s1317" xml:space="preserve">Il faut auſſi prendre garde que le compas ſoit bien
              <lb/>
            au centre, c'eſt-à-dire qu'étant ouvert entierement, il ne faſſe qu'u-
              <lb/>
            ne ligne droite en dedans comme en dehors, & </s>
            <s xml:id="echoid-s1318" xml:space="preserve">que les jambes
              <lb/>
            ſoient bien égales d'épaiſſeur & </s>
            <s xml:id="echoid-s1319" xml:space="preserve">de largeur; </s>
            <s xml:id="echoid-s1320" xml:space="preserve">en un mot qu'il ſoit
              <lb/>
            bien droit en tous ſens. </s>
            <s xml:id="echoid-s1321" xml:space="preserve">La longueur & </s>
            <s xml:id="echoid-s1322" xml:space="preserve">largeur deſdites regles n'eſt
              <lb/>
            pas déterminée, mais on donne pour l'ordinaire ſix pouces de long,
              <lb/>
            ſix à ſept lignes de large, & </s>
            <s xml:id="echoid-s1323" xml:space="preserve">environ deux lignes d'épaiſſeur à chaque
              <lb/>
            jambe des compas de proportion que l'on deſtine pour travailler
              <lb/>
            dans le cabinet. </s>
            <s xml:id="echoid-s1324" xml:space="preserve">On en fait de plus petits, pour être commodément
              <lb/>
            portez dans la poche, comme auſſi de plus grands, pour travailler
              <lb/>
            ſur le terrain, dont on proportionne la largeur & </s>
            <s xml:id="echoid-s1325" xml:space="preserve">épaiſſeur.</s>
            <s xml:id="echoid-s1326" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s1327" xml:space="preserve">On a coutume d'y tracer ſix ſortes de lignes; </s>
            <s xml:id="echoid-s1328" xml:space="preserve">ſçavoir la ligne des
              <lb/>
            parties égales, celle des plans & </s>
            <s xml:id="echoid-s1329" xml:space="preserve">celle des poligones d'un côté; </s>
            <s xml:id="echoid-s1330" xml:space="preserve">la li
              <lb/>
            gne des cordes, celle des ſolides & </s>
            <s xml:id="echoid-s1331" xml:space="preserve">celle des metaux de l'autre côté
              <lb/>
            des jambes dudit compas, en la maniere que nous allons expliquer.</s>
            <s xml:id="echoid-s1332" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s1333" xml:space="preserve">On met encore ordinairement ſur le bord du compas de propor-
              <lb/>
            tion d'un côté un ligne diviſée, qui ſert à connoître le calibre des
              <lb/>
            canons, & </s>
            <s xml:id="echoid-s1334" xml:space="preserve">de l'autre côté une ligne qui ſert à connoître le diame-
              <lb/>
            tre, & </s>
            <s xml:id="echoid-s1335" xml:space="preserve">le poids des boulets de fer, depuis un quart juſqu'à ſoixante-
              <lb/>
            quatre livres, dont nous donnerons la conſtruction & </s>
            <s xml:id="echoid-s1336" xml:space="preserve">les uſages,
              <lb/>
            en parlant des inſtrumens pour l'artillerie.</s>
            <s xml:id="echoid-s1337" xml:space="preserve"/>
          </p>
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        <div xml:id="echoid-div166" type="section" level="1" n="50">
          <head xml:id="echoid-head88" xml:space="preserve">SECTION I.</head>
          <head xml:id="echoid-head89" style="it" xml:space="preserve">De la ligne des parties égales.</head>
          <p>
            <s xml:id="echoid-s1338" xml:space="preserve">CEtte ligne eſt ainſi nommée, parce qu'elle eſt diviſée en par-
              <lb/>
            ties égales, dont le nombre eſt ordinairement 200, lorſqu'elle
              <lb/>
            eſt de ſix pouces de long.</s>
            <s xml:id="echoid-s1339" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s1340" xml:space="preserve">A yant tiré ſur une des ſurfaces de chaque jambe les lignes égales
              <lb/>
              <note position="left" xlink:label="note-044-01" xlink:href="note-044-01a" xml:space="preserve">VI.
                <lb/>
              Planche.
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              Fig. I.</note>
            AB depuis le point A, qui eſt le centre de la charniere du compas,
              <lb/>
            & </s>
            <s xml:id="echoid-s1341" xml:space="preserve">par conſequent le centre de ſon mouvement, qui a été trouvé
              <lb/>
            </s>
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