Gravesande, Willem Jacob 's, An essay on perspective

Table of figures

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              <pb o="118" file="0194" n="223" rhead="An ESSAY"/>
            are to be repreſented upon the Paper in the Frame
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            G.</s>
            <s xml:id="echoid-s2557" xml:space="preserve"/>
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            <s xml:id="echoid-s2558" xml:space="preserve">43. </s>
            <s xml:id="echoid-s2559" xml:space="preserve">There are two pieces of Wood, (one of
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            which is repreſented in Fig. </s>
            <s xml:id="echoid-s2560" xml:space="preserve">77.) </s>
            <s xml:id="echoid-s2561" xml:space="preserve">ſerving to
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            ſuſtain the Box upon its Support or Foot. </s>
            <s xml:id="echoid-s2562" xml:space="preserve">One
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            of theſe Pieces may be faſtned to one Side of the
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            Support, and the other to the other Side thereof,
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            by means of four Iron Pins, two of which go thro
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            the Holes N and P in the Side of the Support,
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            and the Holes T and V in the Piece R, and the
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            other two in like manner, through Holes made
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            in the other Side of the Support, and the other
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            Piece, when we have Mind the Bottom of the
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            Box ſhould be parallel to the Horizon; </s>
            <s xml:id="echoid-s2563" xml:space="preserve">but when
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            the Box is to be a little inclin’d, that Pin going
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            through the Hole P, muſt be put through the
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            Hole O, in the Piece R. </s>
            <s xml:id="echoid-s2564" xml:space="preserve">Underſtand the ſame
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            of the other Piece.</s>
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            <s xml:id="echoid-s2566" xml:space="preserve">44. </s>
            <s xml:id="echoid-s2567" xml:space="preserve">We are ſometimes obliged to ſet the Box
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            forwarder on its Support; </s>
            <s xml:id="echoid-s2568" xml:space="preserve">and this is done, in
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            uſing the Holes Q and S, inſtead of N and P. </s>
            <s xml:id="echoid-s2569" xml:space="preserve">It
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            is likewiſe ſomething neceſſary to incline the
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            Box a little backwards; </s>
            <s xml:id="echoid-s2570" xml:space="preserve">which may be done, by
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            putting the Pin in S, into the Hole X, made in
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            a Piece of Wood faſtned to the Back-ſide of the
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            Box, and the correſpondent Pin on the other Side,
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            into another Hole made on the other Side of the
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            ſaid Piece.</s>
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            <s xml:id="echoid-s2572" xml:space="preserve">45. </s>
            <s xml:id="echoid-s2573" xml:space="preserve">The Box ♈ ſlides upon the Top of the
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            Machine, and is like that already deſcribed,
              <note symbol="*" position="left" xlink:label="note-0194-01" xlink:href="note-0194-01a" xml:space="preserve">10, 11,
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              13.</note>
            with this Difference only, that it is leſſer. </s>
            <s xml:id="echoid-s2574" xml:space="preserve">On
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            the Top of the Box are two little Staples Z Z,
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            in which a Ruler ſlides, having a Mirrour faſtned
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            to it, in the Manner as is mentioned Numb. </s>
            <s xml:id="echoid-s2575" xml:space="preserve">13.
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            </s>
            <s xml:id="echoid-s2576" xml:space="preserve">and ſo by this Means the ſaid Mirrour may be
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            put in the ſame Situation, as that in the Figure
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            of the firſt Machine it hath in H.</s>
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