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

Table of figures

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[63] 32A B
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[69] 6
[70] 7
[71] 8
[72] 9
[73] 10C B D A
[74] 10c b d a
[75] 11B A C
[76] 11B C A D
[77] 12
[78] 13
[79] 14
[80] 15
[81] 16
[82] 17
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        <div xml:id="echoid-div380" type="section" level="1" n="174">
          <p>
            <s xml:id="echoid-s4338" xml:space="preserve">
              <pb o="133" file="147" n="147" rhead="POUR LEVER LES PLANS. Liv. IV. Ch. II."/>
            gne comme L M, égale à B I, en telle ſorte que la diſtance I L ſoit
              <lb/>
            égale à CG; </s>
            <s xml:id="echoid-s4339" xml:space="preserve">tracez enſuite une ligne droite du piquet H au piquet
              <lb/>
            M que vous prolongerez tant qu'il ſera beſoin, cette ligne ſera pa-
              <lb/>
            rallele à la gallerie propoſée à faire de A en B; </s>
            <s xml:id="echoid-s4340" xml:space="preserve">c'eſt pourquoi on
              <lb/>
            pourra planter en diſtance égale de cette parallele H M de côte & </s>
            <s xml:id="echoid-s4341" xml:space="preserve">
              <lb/>
            d'autre de la bute, tant de piquets que l'on voudra, comme O, P,
              <lb/>
            Q, qui ſerviront à percer la bute de A en B.</s>
            <s xml:id="echoid-s4342" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s4343" xml:space="preserve">Je parlerai encore de l'uſage de ces Inſtrumens, dans le petit
              <lb/>
            Traité de Fortiſication, que je donnerai ci-après.</s>
            <s xml:id="echoid-s4344" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div382" type="section" level="1" n="175">
          <head xml:id="echoid-head265" xml:space="preserve">CHAPITRE II.</head>
          <head xml:id="echoid-head266" style="it" xml:space="preserve">Contenant la deſcription & l'uſage de l'Equerre d'Arpenteur.</head>
          <note position="right" xml:space="preserve">Fig. A.</note>
          <p>
            <s xml:id="echoid-s4345" xml:space="preserve">L'Equerre d'Arpenteur eſt un cercle de cuivre d'une bonne épaiſ-
              <lb/>
              <note position="right" xlink:label="note-147-02" xlink:href="note-147-02a" xml:space="preserve">XII.
                <lb/>
              Planche.</note>
            ſeur & </s>
            <s xml:id="echoid-s4346" xml:space="preserve">de 4, 5 ou 6 pouces de diametre. </s>
            <s xml:id="echoid-s4347" xml:space="preserve">Ou le diviſe en qua-
              <lb/>
            tre parties égales par deux lignes qui s'entrecoupent à angles droits
              <lb/>
            au centre. </s>
            <s xml:id="echoid-s4348" xml:space="preserve">Aux quatre extremitez de ces lignes & </s>
            <s xml:id="echoid-s4349" xml:space="preserve">au milieu du lim-
              <lb/>
            be on y met quatre fortes pinules bien rivées dans des trous quar-
              <lb/>
            rez, & </s>
            <s xml:id="echoid-s4350" xml:space="preserve">très-perpendiculairement fenduës ſur leſdites lignes, avec des
              <lb/>
            trous au-deſſous de chaque fente pour mieux découvrir les objets
              <lb/>
            en campagne. </s>
            <s xml:id="echoid-s4351" xml:space="preserve">On évuide ce cercle pour le rendre plus leger.</s>
            <s xml:id="echoid-s4352" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s4353" xml:space="preserve">Au deſſous & </s>
            <s xml:id="echoid-s4354" xml:space="preserve">au centre de l'Inſtrument ſe doit monter à vis une
              <lb/>
            virole qui ſert à ſoûtenir l'Equerre ſur ſon bâton de 4 à 5 pieds ſui-
              <lb/>
            vant la hauteur de l'œil de l'Obſervateur. </s>
            <s xml:id="echoid-s4355" xml:space="preserve">Ce bâton doït être garni
              <lb/>
              <note position="right" xlink:label="note-147-03" xlink:href="note-147-03a" xml:space="preserve">Fig. B.</note>
            d'un fer pointu par le bout pui entre en terre, & </s>
            <s xml:id="echoid-s4356" xml:space="preserve">l'autre bout doit
              <lb/>
            être arrondi pour que la virole y reſte juſte.</s>
            <s xml:id="echoid-s4357" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s4358" xml:space="preserve">Toute la préciſion de cet Inſtrument conſiſte en ce que les pinu-
              <lb/>
            les ſoient bien exactement fenduës à angles droits; </s>
            <s xml:id="echoid-s4359" xml:space="preserve">ce que l'on con-
              <lb/>
            noîtra facilement en bornaïant un objet éloigné par deux pinules,
              <lb/>
            & </s>
            <s xml:id="echoid-s4360" xml:space="preserve">uu autre objet par les deux autres pinules. </s>
            <s xml:id="echoid-s4361" xml:space="preserve">Il faut enſuite tourner
              <lb/>
            l'Equerre bien juſte ſur ſon bâton, & </s>
            <s xml:id="echoid-s4362" xml:space="preserve">regarder les mêmes objets par
              <lb/>
            les pinules oppoſées; </s>
            <s xml:id="echoid-s4363" xml:space="preserve">s'ils ſe rencontrent bien exactement dans l'ali-
              <lb/>
            gnement des fentes, c'eſt une marque de la juſteſſe de l'inſtrument.</s>
            <s xml:id="echoid-s4364" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s4365" xml:space="preserve">Pour éviter de fauſſer l'Equerre, il faut premierement enfoncer
              <lb/>
            en terre le bâton ſeul, & </s>
            <s xml:id="echoid-s4366" xml:space="preserve">quand il eſt bien affermi, placer ladite
              <lb/>
            Equerre ſur la virole par le moyen de ſa vis.</s>
            <s xml:id="echoid-s4367" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s4368" xml:space="preserve">On fait auſſi de ces ſortes d'Equerres, où l'on met huit pinules de
              <lb/>
            la même maniere que celle décrite ci-deſſus; </s>
            <s xml:id="echoid-s4369" xml:space="preserve">elles ſervent pour avoir
              <lb/>
            lcs Angles de 45 degrez; </s>
            <s xml:id="echoid-s4370" xml:space="preserve">comme auſſi aux Jardiniers, pour aligner
              <lb/>
            & </s>
            <s xml:id="echoid-s4371" xml:space="preserve">planter les Allées d'Arbres en étoile.</s>
            <s xml:id="echoid-s4372" xml:space="preserve"/>
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