Gravesande, Willem Jacob 's, An essay on perspective
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              <pb o="83" file="0145" n="167" rhead="on PERSPECTIVE."/>
            after which, I ſhall touch upon thoſe continually
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            increaſing. </s>
            <s xml:id="echoid-s1923" xml:space="preserve">What I ſhall ſay on this Matter, is
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            ſufficient for deſigning the Shadows of right-lin’d
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            Bodies; </s>
            <s xml:id="echoid-s1924" xml:space="preserve">as to the Shadows of other Bodies, it
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            is ſo difficult to determine them Geometrically
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            that it is much better to examine thoſe which are
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            daily obſerved, and ſo imitate them.</s>
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            <s xml:id="echoid-s1926" xml:space="preserve">I ſhall not ſay any thing concerning Shadows
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            terminating in a Point, becauſe their Variety
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            is ſo great, that they cannot be geometrically de-
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            termin’d. </s>
            <s xml:id="echoid-s1927" xml:space="preserve">Beſides, Painters ſcarcely ever ſup-
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            poſe their perſpective Planes or Pictures en-
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            lightned after this third Manner, unleſs only
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            when they have a Mind to repreſent a Chamber,
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            wherein the Light enters through the Windows;
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            </s>
            <s xml:id="echoid-s1928" xml:space="preserve">but then the Number of Windows, their Situati-
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            on, and the different Reflections that the Light
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            ſuffers in the Chamber, produce ſo many dif-
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            ferent Alterations, that a Painter had better
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            imitate them, than have recourſe to Rules that
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            do not take in all Caſes. </s>
            <s xml:id="echoid-s1929" xml:space="preserve">I ſhall likewiſe be ſi-
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            lent as to the clair-obſcure, for a ſmall Atten-
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            tion to daily Experience will better illuſtrate
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            this Matter than a long Diſcourſe thereon. </s>
            <s xml:id="echoid-s1930" xml:space="preserve">Be-
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            ſides, it is impoſſible to furniſh general Rules
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            on this Subject; </s>
            <s xml:id="echoid-s1931" xml:space="preserve">and likewiſe the vaſt Number
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            of Figures, will not permit us to ſeparately
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            examine them; </s>
            <s xml:id="echoid-s1932" xml:space="preserve">add to all this, that a Painter
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            to draw the clair-obſcure, he ought to have, not
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            only regard to the Figures of Objects, but likwiſe
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            to their Colour and Matter.</s>
            <s xml:id="echoid-s1933" xml:space="preserve"/>
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        <div xml:id="echoid-div305" type="section" level="1" n="165">
          <head xml:id="echoid-head172" style="it" xml:space="preserve">Of Solar Shadows.</head>
          <head xml:id="echoid-head173" xml:space="preserve">
            <emph style="sc">Problem</emph>
          I.</head>
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            <s xml:id="echoid-s1934" xml:space="preserve">103. </s>
            <s xml:id="echoid-s1935" xml:space="preserve">To find the Perſpective of the Shadow of a
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            Point above the Geometrical Plane, whoſe Height and
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            Seat is given.</s>
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