Gravesande, Willem Jacob 's, An essay on perspective

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        <div xml:id="echoid-div83" type="section" level="1" n="46">
          <p>
            <s xml:id="echoid-s676" xml:space="preserve">
              <pb o="24" file="0048" n="51" rhead="An ESSAY"/>
            thod, unleſs by Means of the Point A, the Ap-
              <lb/>
            pearance of ſome other Point taken at Pleaſure
              <lb/>
            upon the Geometrical Plane be found, by Means
              <lb/>
            of which, the Appearance of the Point B may
              <lb/>
            be afterwards gotten; </s>
            <s xml:id="echoid-s677" xml:space="preserve">but in theſe Caſes, the
              <lb/>
            ſhorteſt Way, is to uſe ſome one of the precedent
              <lb/>
            Methods.</s>
            <s xml:id="echoid-s678" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div84" type="section" level="1" n="47">
          <head xml:id="echoid-head49" xml:space="preserve">
            <emph style="sc">Corollary</emph>
          .</head>
          <p>
            <s xml:id="echoid-s679" xml:space="preserve">38. </s>
            <s xml:id="echoid-s680" xml:space="preserve">It appears from this Method, that when
              <lb/>
            the Repreſentations of two Points are found,
              <lb/>
            the Appearance of any third Point whatſoever
              <lb/>
            may be had, without having any Regard to the
              <lb/>
            Situation of the Eye; </s>
            <s xml:id="echoid-s681" xml:space="preserve">becauſe two Lines as E a
              <lb/>
            may be drawn, whoſe Interſection will be the
              <lb/>
            Point ſought.</s>
            <s xml:id="echoid-s682" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div85" type="section" level="1" n="48">
          <head xml:id="echoid-head50" xml:space="preserve">
            <emph style="sc">Method</emph>
          VI.</head>
          <p>
            <s xml:id="echoid-s683" xml:space="preserve">39. </s>
            <s xml:id="echoid-s684" xml:space="preserve">The ſame things being given, as in the
              <lb/>
              <note position="left" xlink:label="note-0048-01" xlink:href="note-0048-01a" xml:space="preserve">Fig. 12.</note>
            ſecond Method, let F C be the Geometrical Line.</s>
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        </div>
        <div xml:id="echoid-div87" type="section" level="1" n="49">
          <head xml:id="echoid-head51" xml:space="preserve">
            <emph style="sc">Operation</emph>
          .</head>
          <p>
            <s xml:id="echoid-s686" xml:space="preserve">Draw two Lines A F and A C from the given
              <lb/>
            Point A at Pleaſure, cutting the Baſe Line in the
              <lb/>
            Points E and B, and interſecting the Geometri-
              <lb/>
            cal Line in the Points F and C. </s>
            <s xml:id="echoid-s687" xml:space="preserve">From theſe
              <lb/>
            two laſt Points draw the Lines F O and C O to
              <lb/>
            the Eye; </s>
            <s xml:id="echoid-s688" xml:space="preserve">then draw E a through the Point E,
              <lb/>
            parallel to F O, and B a through the Point B,
              <lb/>
            parallel to C O, and the Point a the Interſection
              <lb/>
            of theſe two Lines will be that ſought.</s>
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          </p>
          <p>
            <s xml:id="echoid-s690" xml:space="preserve">Note, We might firſt have drawn the Lines
              <lb/>
            O F and O C at Pleaſure, and then have drawn
              <lb/>
            the Lines AC and A F through their </s>
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