Bélidor, Bernard Forest de, La science des ingenieurs dans la conduite des travaux de fortification et d' architecture civile

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        <div xml:id="echoid-div137" type="section" level="1" n="85">
          <div xml:id="echoid-div171" type="section" level="2" n="18">
            <pb o="24" file="0132" n="135" rhead="LA SCIENCE DES INGENIEURS,"/>
          </div>
          <div xml:id="echoid-div172" type="section" level="2" n="19">
            <head xml:id="echoid-head130" style="it" xml:space="preserve">Remarque prémiere.</head>
            <p>
              <s xml:id="echoid-s2528" xml:space="preserve">18. </s>
              <s xml:id="echoid-s2529" xml:space="preserve">Pour juger combien il faudroit moins de Maçonnerie pour
                <lb/>
              les piés-droits de la Voûte que nous venons de calculer, que pour
                <lb/>
              ceux du premier Problême, il n’y a qu’à comparer l’épaiſſeur du
                <lb/>
              Profil de l’un, avec celle du Profil de l’autre, puiſqu’ils ontla même
                <lb/>
              hauteur: </s>
              <s xml:id="echoid-s2530" xml:space="preserve">pour cela j’ajoûte les lignes ZB & </s>
              <s xml:id="echoid-s2531" xml:space="preserve">PS enſemble; </s>
              <s xml:id="echoid-s2532" xml:space="preserve">c’eſt-à-
                <lb/>
              dire 3 pieds 9 pouces 3 lignes, & </s>
              <s xml:id="echoid-s2533" xml:space="preserve">6 pieds 9 pouces 3 lignes, & </s>
              <s xml:id="echoid-s2534" xml:space="preserve">
                <lb/>
              prens la moitié de la ſomme qui eſt de 5 pieds 3 pouces 3 lignes
                <lb/>
              pour l’épaiſſeur réduite, qui étant comparée avec 6 pieds 6 pouces
                <lb/>
              7 lignes, épaiſſeur des piés-droits du premier Probléme, la diffé-
                <lb/>
              rence ſera d’un pied trois pouces 4 lignes: </s>
              <s xml:id="echoid-s2535" xml:space="preserve">ce qui fait voir qu’en don-
                <lb/>
              nant au pié-droit un talud tel que nous l’avons ſupoſé, on employera
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              environ un cinquiéme moins de Maçonnerie, que ſi l’on avoit fait
                <lb/>
              ces pié-droits à plomb des deux côtés.</s>
              <s xml:id="echoid-s2536" xml:space="preserve"/>
            </p>
          </div>
          <div xml:id="echoid-div173" type="section" level="2" n="20">
            <head xml:id="echoid-head131" style="it" xml:space="preserve">Remarque ſeconde.</head>
            <p>
              <s xml:id="echoid-s2537" xml:space="preserve">19. </s>
              <s xml:id="echoid-s2538" xml:space="preserve">Quand on a trouvé, comme dans le premier Probléme, l’é-
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              paiſſeur qu’il faut donner aux piés-droits d’une Voûte, pour être en
                <lb/>
              équilibre avec la pouſſée, on peut ſans augmenter la depenſe mettre
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              la réſiſtance des piés-droits beaucoup au-deſſus de la pouſſée afin d’ê-
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              tre ſûr que quelque choſe qui arrive les piés-droits demeurerontiné-
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              branlables: </s>
              <s xml:id="echoid-s2539" xml:space="preserve">pour cela il ne faut que diminuer un peu l’épaiſſeur des
                <lb/>
              piés-droits au ſommet, & </s>
              <s xml:id="echoid-s2540" xml:space="preserve">augmenter celle de la baſe de la même quan-
                <lb/>
              tité; </s>
              <s xml:id="echoid-s2541" xml:space="preserve">par exemple, ſi l’on a trouvé qu’il falloit 7 pieds d’épaiſſeur aux
                <lb/>
              piés-droits, on en donnera 6 au ſommet & </s>
              <s xml:id="echoid-s2542" xml:space="preserve">8 à la baſe.</s>
              <s xml:id="echoid-s2543" xml:space="preserve"/>
            </p>
            <p>
              <s xml:id="echoid-s2544" xml:space="preserve">Les murs, qui ſont expoſés à l’injure de l’air, & </s>
              <s xml:id="echoid-s2545" xml:space="preserve">qui ont un talud,
                <lb/>
              étant plus ſujets à être dégradés que ceux qui n’en ont point, on
                <lb/>
              ne manquera pas de dire que dans la pratique on fera peu d’atten-
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              tion à l’avantage que je prétend en tirer: </s>
              <s xml:id="echoid-s2546" xml:space="preserve">l’on prendra là-deſſus le
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              parti qu’on jugera à propos, ce que l’on vient d’enſeigner n’en ſera
                <lb/>
              pas moins vrai.</s>
              <s xml:id="echoid-s2547" xml:space="preserve"/>
            </p>
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