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-s7563" xml:space="preserve">
              <pb o="243" file="258" n="258" rhead="D'OBSERVER LES ASTRES. Liv. VI. Chap. III."/>
            même hauteur, devant & </s>
            <s xml:id="echoid-s7564" xml:space="preserve">après le Solſtice, étant dans le même
              <lb/>
            cercle parallele à l'Equateur.</s>
            <s xml:id="echoid-s7565" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s7566" xml:space="preserve">Ayant donc connu le tems écoulé entre l'une & </s>
            <s xml:id="echoid-s7567" xml:space="preserve">l'autre ſituation
              <lb/>
            du Soleil, il en faut prendre le milieu, & </s>
            <s xml:id="echoid-s7568" xml:space="preserve">chercher dans les Tables le
              <lb/>
            vrai lieu du Soleil qui convient à ces trois tems. </s>
            <s xml:id="echoid-s7569" xml:space="preserve">Le milieu de la dif-
              <lb/>
            ference des lieux extrêmes du Soleil s'ajoûtera au moindre, afin d'en
              <lb/>
            faire un lieu moyen par la comparaiſon des extrêmes; </s>
            <s xml:id="echoid-s7570" xml:space="preserve">mais ſi le lieu
              <lb/>
            moyen trouvé par le calcul ne convient pas au lieu moyen trouvé
              <lb/>
            par ladite comparaiſon, il faut en prendre la difference & </s>
            <s xml:id="echoid-s7571" xml:space="preserve">ajoûter au
              <lb/>
            tems moyen le tems qui répond à cette difference, ſi le tems moyen
              <lb/>
            trouvé par le calcul eſt le plus petit, & </s>
            <s xml:id="echoid-s7572" xml:space="preserve">au contraire le ſouſtraire s'il
              <lb/>
            eſt plus grand, afin d'avoir le tems du Solſtice.</s>
            <s xml:id="echoid-s7573" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div542" type="section" level="1" n="261">
          <head xml:id="echoid-head384" xml:space="preserve">EXEMPLE.</head>
          <p>
            <s xml:id="echoid-s7574" xml:space="preserve">Le dixiéme jour du mois de Juin la hauteur Méridienc apparen-
              <lb/>
            te du Soleil a été trouvée dans l'Obſervatoire Roïal de 94d. </s>
            <s xml:id="echoid-s7575" xml:space="preserve">27 m.
              <lb/>
            </s>
            <s xml:id="echoid-s7576" xml:space="preserve">25 ſec. </s>
            <s xml:id="echoid-s7577" xml:space="preserve">& </s>
            <s xml:id="echoid-s7578" xml:space="preserve">le 3
              <emph style="sub">me</emph>
            jour de Juillet enſuite, ladite hauteur Méridiene
              <lb/>
            apparente s'eſt trouvée de 64d. </s>
            <s xml:id="echoid-s7579" xml:space="preserve">28 m. </s>
            <s xml:id="echoid-s7580" xml:space="preserve">15 ſec. </s>
            <s xml:id="echoid-s7581" xml:space="preserve">d'où l'on connoît
              <lb/>
            par la difference de déclinaiſon en ce tems, que le Soleil eſt arrivéau
              <lb/>
            parallele de la premiere obſervation le 3
              <emph style="sub">me</emph>
            jour de Juillet à 4 h. </s>
            <s xml:id="echoid-s7582" xml:space="preserve">12
              <lb/>
            min. </s>
            <s xml:id="echoid-s7583" xml:space="preserve">& </s>
            <s xml:id="echoid-s7584" xml:space="preserve">par conſequent le tems moyen entre les obſervations ſera
              <lb/>
            le 22 Juin à 2 h. </s>
            <s xml:id="echoid-s7585" xml:space="preserve">& </s>
            <s xml:id="echoid-s7586" xml:space="preserve">6 m. </s>
            <s xml:id="echoid-s7587" xml:space="preserve">du matin.</s>
            <s xml:id="echoid-s7588" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s7589" xml:space="preserve">Or par les Tables, le vrai lieu du Soleil au tems de la premiere
              <lb/>
            obſervation eſt 2 ſignes, 58 m. </s>
            <s xml:id="echoid-s7590" xml:space="preserve">23 ſec. </s>
            <s xml:id="echoid-s7591" xml:space="preserve">& </s>
            <s xml:id="echoid-s7592" xml:space="preserve">au tems de la dernie-
              <lb/>
            re il eſt 3 ſig 11 d. </s>
            <s xml:id="echoid-s7593" xml:space="preserve">4 m. </s>
            <s xml:id="echoid-s7594" xml:space="preserve">52 ſec. </s>
            <s xml:id="echoid-s7595" xml:space="preserve">& </s>
            <s xml:id="echoid-s7596" xml:space="preserve">au milieu il eſt 3 ſig. </s>
            <s xml:id="echoid-s7597" xml:space="preserve">od. </s>
            <s xml:id="echoid-s7598" xml:space="preserve">1 m. </s>
            <s xml:id="echoid-s7599" xml:space="preserve">56 ſec.</s>
            <s xml:id="echoid-s7600" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s7601" xml:space="preserve">Mais la difference des lieux extrêmes eſt 22 d. </s>
            <s xml:id="echoid-s7602" xml:space="preserve">6 m. </s>
            <s xml:id="echoid-s7603" xml:space="preserve">29 ſec. </s>
            <s xml:id="echoid-s7604" xml:space="preserve">dont
              <lb/>
            la moitié eſt 11 d. </s>
            <s xml:id="echoid-s7605" xml:space="preserve">3 m. </s>
            <s xml:id="echoid-s7606" xml:space="preserve">15 ſec. </s>
            <s xml:id="echoid-s7607" xml:space="preserve">leſquels ajoûtez au moindre lieu font
              <lb/>
            3 ſig. </s>
            <s xml:id="echoid-s7608" xml:space="preserve">od. </s>
            <s xml:id="echoid-s7609" xml:space="preserve">1 m. </s>
            <s xml:id="echoid-s7610" xml:space="preserve">38 ſec. </s>
            <s xml:id="echoid-s7611" xml:space="preserve">lequel eſt le lieu moyen par la comparaiſon
              <lb/>
            des extrêmes.</s>
            <s xml:id="echoid-s7612" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s7613" xml:space="preserve">Entre le lieu moyen par le calcul 3 ſig. </s>
            <s xml:id="echoid-s7614" xml:space="preserve">o d. </s>
            <s xml:id="echoid-s7615" xml:space="preserve">1 m. </s>
            <s xml:id="echoid-s7616" xml:space="preserve">56 ſec. </s>
            <s xml:id="echoid-s7617" xml:space="preserve">& </s>
            <s xml:id="echoid-s7618" xml:space="preserve">le lieu
              <lb/>
            moyen par comparaiſon, la difference eſt 18 ſec. </s>
            <s xml:id="echoid-s7619" xml:space="preserve">qui correſpondent
              <lb/>
            à 7 m. </s>
            <s xml:id="echoid-s7620" xml:space="preserve">18 ſec. </s>
            <s xml:id="echoid-s7621" xml:space="preserve">de tems qu'il faut ôter du tems moyen, parce que le
              <lb/>
            lieu moyen par le calcul eſt plus grand que le lieu moyen par com-
              <lb/>
            paraiſon. </s>
            <s xml:id="echoid-s7622" xml:space="preserve">C'eſt pourquoi le tems du Solſtice ſera le 22 Juin à une
              <lb/>
            heure 58 min. </s>
            <s xml:id="echoid-s7623" xml:space="preserve">18 ſec. </s>
            <s xml:id="echoid-s7624" xml:space="preserve">du matin. </s>
            <s xml:id="echoid-s7625" xml:space="preserve">Ce qui peut ſe confirmer par plu-
              <lb/>
            ſieurs autres obſervations.</s>
            <s xml:id="echoid-s7626" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s7627" xml:space="preserve">Il eſt à remarquer que l'erreur de peu de ſecondes, plus ou moins
              <lb/>
            dans la hauteur du Soleil obſervée, peut éloigner d'une heure le Sol-
              <lb/>
            ſtice de ſon vrai tems, comme en l'exemple propoſé 10 ſec. </s>
            <s xml:id="echoid-s7628" xml:space="preserve">de hau-
              <lb/>
            teur ou environ répondent à une heure detems; </s>
            <s xml:id="echoid-s7629" xml:space="preserve">c'eſt pourquoi cela
              <lb/>
            ne ſe peut faire qu'avec des Inſtrumens bien diviſez & </s>
            <s xml:id="echoid-s7630" xml:space="preserve">pluſieurs ob-
              <lb/>
            ſervations très-exactes.</s>
            <s xml:id="echoid-s7631" xml:space="preserve"/>
          </p>
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