Gravesande, Willem Jacob 's, An essay on perspective

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        <div xml:id="echoid-div386" type="section" level="1" n="207">
          <pb o="115" file="0191" n="220" rhead="on PERSPECTIVE."/>
        </div>
        <div xml:id="echoid-div387" type="section" level="1" n="208">
          <head xml:id="echoid-head228" style="it" xml:space="preserve">The Height of the Machine above the Table;
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          So is
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          The Glaſſes focal Length,
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          to the
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          Diſtance of the Figure from the Glaſs.</head>
          <p>
            <s xml:id="echoid-s2510" xml:space="preserve">Note, The ſaid Diſtance of the Convex Glaſs
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            from the Figure, is meaſured by a Ray, pro-
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            ceeding from the Figure parallel to the Horizon,
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            which is perpendicularly reflected upon the Con-
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            vex Glaſs, by the Mirrour. </s>
            <s xml:id="echoid-s2511" xml:space="preserve">Note, Moreover, that
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            when we have a Mind to place the Figures out
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            beyond the Back-ſide of the Machine, they muſt
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            be faſtned againſt the Side F of the Board, which
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            muſt be ſo turned, that the ſaid Side be next to
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            the Aperture N.</s>
            <s xml:id="echoid-s2512" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div388" type="section" level="1" n="209">
          <head xml:id="echoid-head229" style="it" xml:space="preserve">37 Remarks concerning the Repreſentation of Per-
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          ſons Faces.</head>
          <p>
            <s xml:id="echoid-s2513" xml:space="preserve">It is certainly very curious and uſeful to de-
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            ſign Perſons Faces to the Life; </s>
            <s xml:id="echoid-s2514" xml:space="preserve">which by this
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            Machine, may be very well done in Miniature:
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            </s>
            <s xml:id="echoid-s2515" xml:space="preserve">For if the Face of any known Perſon be thus re-
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            preſented, by only looking at the Appearance,
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            we may very readily know whoſe Face it is,
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            when at the ſame time the Appearance of the
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            Whole Perſon will not take up half an Inch
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            upon the Paper on the Table: </s>
            <s xml:id="echoid-s2516" xml:space="preserve">But it is very dif-
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            ficult to repreſent a Face diſtinctly as big as the
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            Life; </s>
            <s xml:id="echoid-s2517" xml:space="preserve">for when we would repreſent a Face in its
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            natural Bigneſs, ſuch a Convex Glaſs as is men-
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            tioned in Numb. </s>
            <s xml:id="echoid-s2518" xml:space="preserve">35. </s>
            <s xml:id="echoid-s2519" xml:space="preserve">muſt be uſed, and the Face
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            placed where the Board F is . </s>
            <s xml:id="echoid-s2520" xml:space="preserve">But the
              <note symbol="*" position="right" xlink:label="note-0191-01" xlink:href="note-0191-01a" xml:space="preserve">35.</note>
            Face which then appears diſtinct enough, that ſo
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            the Perſon whereof it is the Repreſentation may
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            thereby be known, hath not its Lineaments ſuffi-
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            ciently enough repreſented, as to be followed by a
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            Painter as they ought, in order to keep the true </s>
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