Gravesande, Willem Jacob 's, An essay on perspective

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        <div xml:id="echoid-div315" type="section" level="1" n="171">
          <pb o="87" file="0153" n="177" rhead="on PERSPECTIVE."/>
        </div>
        <div xml:id="echoid-div317" type="section" level="1" n="172">
          <head xml:id="echoid-head181" xml:space="preserve">
            <emph style="sc">Remarks</emph>
          .</head>
          <p>
            <s xml:id="echoid-s2000" xml:space="preserve">What hath been obſerved on the Solar
              <note position="right" xlink:label="note-0153-01" xlink:href="note-0153-01a" xml:space="preserve">105.</note>
            dows, hath no Regard to thoſe mentioned here:
              <lb/>
            </s>
            <s xml:id="echoid-s2001" xml:space="preserve">For it matters not in this Problem, whether the
              <lb/>
            perſpective Plane be perpendicular, inclined, or
              <lb/>
            parallel; </s>
            <s xml:id="echoid-s2002" xml:space="preserve">becauſe in theſe different Situations, the
              <lb/>
            two Points that are uſed may always be found.</s>
            <s xml:id="echoid-s2003" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s2004" xml:space="preserve">Moreover, it muſt be obſerved, that the third
              <lb/>
            Problem takes in the Shadows of a ſmall
              <note symbol="*" position="right" xlink:label="note-0153-02" xlink:href="note-0153-02a" xml:space="preserve">106.</note>
            as well as thoſe of the Sun; </s>
            <s xml:id="echoid-s2005" xml:space="preserve">but not without this
              <lb/>
            Difference, that the Plane which in the third
              <lb/>
            Problem is ſuppoſed parallel to the Sun’s Rays,
              <lb/>
            ought here to be ſuppoſed to paſs through the
              <lb/>
            Light whoſe Shadows are ſought.</s>
            <s xml:id="echoid-s2006" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div320" type="section" level="1" n="173">
          <head xml:id="echoid-head182" xml:space="preserve">CHAP. VIII.</head>
          <head xml:id="echoid-head183" style="it" xml:space="preserve">Of mechanically ſhortning the Operations of
            <lb/>
          Perſpective.</head>
          <head xml:id="echoid-head184" xml:space="preserve">1. WHEN the perſpective Plane is ſup-
            <lb/>
          pos’d perpendicular or upright.</head>
          <head xml:id="echoid-head185" xml:space="preserve">
            <emph style="sc">Problem</emph>
          I.</head>
          <p style="it">
            <s xml:id="echoid-s2007" xml:space="preserve">109. </s>
            <s xml:id="echoid-s2008" xml:space="preserve">To find the Repreſentations of Figures in
              <lb/>
            the Geometrical Plane.</s>
            <s xml:id="echoid-s2009" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s2010" xml:space="preserve">Let O be the Eye, R H the Baſe Line; </s>
            <s xml:id="echoid-s2011" xml:space="preserve">F and
              <lb/>
              <note position="right" xlink:label="note-0153-03" xlink:href="note-0153-03a" xml:space="preserve">Fig. 60</note>
            G the Points denoted with the ſame Letters in
              <lb/>
            Fig. </s>
            <s xml:id="echoid-s2012" xml:space="preserve">10. </s>
            <s xml:id="echoid-s2013" xml:space="preserve"/>
          </p>
          <note symbol="*" position="right" xml:space="preserve">31.</note>
          <p>
            <s xml:id="echoid-s2014" xml:space="preserve">Then take a Ruler and faſten to the Point G,
              <lb/>
            ſo that it may turn about the ſame in ſuch man.</s>
            <s xml:id="echoid-s2015" xml:space="preserve"/>
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