Gravesande, Willem Jacob 's, An essay on perspective

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        <div xml:id="echoid-div240" type="section" level="1" n="126">
          <p>
            <s xml:id="echoid-s1671" xml:space="preserve">
              <pb o="69" file="0125" n="144" rhead="on PERSPECTIVE."/>
            too obliquely, recourſe muſt be had to Problem I. </s>
            <s xml:id="echoid-s1672" xml:space="preserve">
              <note symbol="*" position="right" xlink:label="note-0125-01" xlink:href="note-0125-01a" xml:space="preserve">81.</note>
            to find the Appearance of a.</s>
            <s xml:id="echoid-s1673" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div243" type="section" level="1" n="127">
          <head xml:id="echoid-head133" xml:space="preserve">
            <emph style="sc">Method</emph>
          II.</head>
          <p>
            <s xml:id="echoid-s1674" xml:space="preserve">85. </s>
            <s xml:id="echoid-s1675" xml:space="preserve">A is the Foot of the Perpendicular: </s>
            <s xml:id="echoid-s1676" xml:space="preserve">The
              <lb/>
              <note position="right" xlink:label="note-0125-02" xlink:href="note-0125-02a" xml:space="preserve">Fig. 46.</note>
            Triangle, E P M, is drawn as directed: </s>
            <s xml:id="echoid-s1677" xml:space="preserve">
              <note symbol="*" position="right" xlink:label="note-0125-03" xlink:href="note-0125-03a" xml:space="preserve">82.</note>
            T is the accidental Point of the Perpendiculars,
              <lb/>
            to the Geometrical Plane.</s>
            <s xml:id="echoid-s1678" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div245" type="section" level="1" n="128">
          <head xml:id="echoid-head134" xml:space="preserve">
            <emph style="sc">Operation</emph>
          .</head>
          <p>
            <s xml:id="echoid-s1679" xml:space="preserve">Thro’ the Point a, the Appearance of A,
              <lb/>
            draw a Perpendicular to the Baſe Line; </s>
            <s xml:id="echoid-s1680" xml:space="preserve">which
              <lb/>
            make equal in Repreſentation to the
              <note symbol="*" position="right" xlink:label="note-0125-04" xlink:href="note-0125-04a" xml:space="preserve">55.</note>
            M E; </s>
            <s xml:id="echoid-s1681" xml:space="preserve">in conſidering this laſt Line, as being
              <lb/>
            parallel to the Vertical Line. </s>
            <s xml:id="echoid-s1682" xml:space="preserve">Then, from the
              <lb/>
            Extremity I of this Perſpective, to the Point of
              <lb/>
            Sight V, draw a Line cutting the Line T a, in
              <lb/>
            the Point X; </s>
            <s xml:id="echoid-s1683" xml:space="preserve">which will be the Repreſentation
              <lb/>
            of the Extremity of the propos’d Line.</s>
            <s xml:id="echoid-s1684" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div247" type="section" level="1" n="129">
          <head xml:id="echoid-head135" xml:space="preserve">
            <emph style="sc">Demonstration</emph>
          .</head>
          <p>
            <s xml:id="echoid-s1685" xml:space="preserve">Let us ſuppoſe a Line paſſing thro’ the Point
              <lb/>
            A, equal to M E, and parallel to the Verti-
              <lb/>
            cal Line. </s>
            <s xml:id="echoid-s1686" xml:space="preserve">Suppoſe, moreover, that another Line
              <lb/>
            is drawn thro’ the Extremity of this Line, and
              <lb/>
            that of the propos’d Perpendicular; </s>
            <s xml:id="echoid-s1687" xml:space="preserve">then this
              <lb/>
            laſt Line, by the Conſtruction of the Figure
              <lb/>
            M E P, will be parallel to the Station Line;
              <lb/>
            </s>
            <s xml:id="echoid-s1688" xml:space="preserve">and conſequently, its Repreſentation will
              <note symbol="*" position="right" xlink:label="note-0125-05" xlink:href="note-0125-05a" xml:space="preserve">16.</note>
            thro’ the Point of Sight; </s>
            <s xml:id="echoid-s1689" xml:space="preserve">and its Interſection
              <lb/>
            with T a, will be the Extremity of the Repre-
              <lb/>
            ſentation ſought. </s>
            <s xml:id="echoid-s1690" xml:space="preserve">But a I is the
              <note symbol="*" position="right" xlink:label="note-0125-06" xlink:href="note-0125-06a" xml:space="preserve">56.</note>
            of the firſt Line, made equal to E M; </s>
            <s xml:id="echoid-s1691" xml:space="preserve">and con-
              <lb/>
            ſequently, V I is that of the ſecond. </s>
            <s xml:id="echoid-s1692" xml:space="preserve">Which was
              <lb/>
            to be demonſtrated.</s>
            <s xml:id="echoid-s1693" xml:space="preserve"/>
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