Gravesande, Willem Jacob 's, An essay on perspective

Table of figures

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[41] page 64Plate. 18.d v
[42] Fig. 41E b a G F H C B A D
[43] Fig. 42G Q A M I S E H T B L Z F P a X Y N C D R O
[44] page 68Plate. 19Fig. 43B D E a G H I C F L
[45] Fig. 44O V X S H I T
[46] Fig. 45Q F V X S a H B C D E L M P T A
[47] page 72Plate. 20Fig. 46V I X a E M P A T
[48] Fig. 47V F X a Q G H D N A T R
[49] Page 34.Plate. 21Fig. 48F O D X S b a G N A E T B P C
[50] Fig. 49H F O D G X a M N L R Q
[51] Page 36Plate 22Fig. 50O R E G N S M
[52] Fig. 51I H T a X
[53] Fig. 52C D X I H G a F E L b T
[54] Fig. 53H I F T x d X L B C
[55] page 64.Plate 23.Fig. 54O M P Q t A X x Q R N
[56] Fig. 55G F b T L a
[57] Fig. 56I F a X b E T C P
[58] page 66.Plate. 24.Fig. 57E A Z C P B
[59] Fig. 58F O D I a b
[60] Fig. 59F E Z C A B
[61] page 88.Plate. 25.Fig. 60O G F f Z L R P D I T S M a Q E R H N A C B
[62] Plate 26Fig. 61O I F T N S Q S H E R M A
[63] Fig. 62C D S Q L C D R P H
[64] page 96.Plate. 27Fig. 63D E C F M H I G P A Q N
[65] Fig. 64X S D E T C R L F H I G P M B O V Q N
[66] page 98.Plate. 28Fig. 65L M F G D H C E I A B
[67] Fig. 66A B VII VIII IV V H C VI VI P V VII IV S VIII E O I III II I XII XIX IX F D
[68] page 100Plate. 29Fig. 675 6p 7 8 9 10 S V VI VII VIII IX X o XI ll l
[69] Fig. 68c P G e o Q
[70] Fig. 69P c G o e Q
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          <p>
            <s xml:id="echoid-s557" xml:space="preserve">
              <pb o="19" file="0041" n="43" rhead="on PERSPECTIVE."/>
            Sight to the Horizontal Line, equal in Length
              <lb/>
            to the principal Ray; </s>
            <s xml:id="echoid-s558" xml:space="preserve">and the Extremity of this
              <lb/>
            Perpendicular will be the Point ſought.</s>
            <s xml:id="echoid-s559" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s560" xml:space="preserve">If nothing is determin’d, the Place of the Eye
              <lb/>
            may be taken at pleaſure in the Horizontal
              <lb/>
            Plane.</s>
            <s xml:id="echoid-s561" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div66" type="section" level="1" n="35">
          <head xml:id="echoid-head37" xml:space="preserve">
            <emph style="sc">Method</emph>
          III.</head>
          <p>
            <s xml:id="echoid-s562" xml:space="preserve">29. </s>
            <s xml:id="echoid-s563" xml:space="preserve">The ſame Things being given as in the
              <lb/>
            precedent Method, about the Eye O, as a Cen-
              <lb/>
            ter; </s>
            <s xml:id="echoid-s564" xml:space="preserve">deſcribe the Arc of a Circle I H, touching
              <lb/>
              <note position="right" xlink:label="note-0041-01" xlink:href="note-0041-01a" xml:space="preserve">Fig. 9.</note>
            the Horizontal Line.</s>
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          </p>
        </div>
        <div xml:id="echoid-div68" type="section" level="1" n="36">
          <head xml:id="echoid-head38" xml:space="preserve">
            <emph style="sc">Operation</emph>
          .</head>
          <p>
            <s xml:id="echoid-s566" xml:space="preserve">About the given Point A, as a Center, de-
              <lb/>
            ſcribe the Arc of a Circle L C, touching the Baſe
              <lb/>
            Line: </s>
            <s xml:id="echoid-s567" xml:space="preserve">Then draw two Lines, C H and L I,
              <lb/>
            touching the two Circles L C and H I; </s>
            <s xml:id="echoid-s568" xml:space="preserve">and the
              <lb/>
            Point a, the Interſection of the ſaid two Lines,
              <lb/>
            will be the Appearance ſought.</s>
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          </p>
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        <div xml:id="echoid-div69" type="section" level="1" n="37">
          <head xml:id="echoid-head39" xml:space="preserve">
            <emph style="sc">Demonstration</emph>
          .</head>
          <p>
            <s xml:id="echoid-s570" xml:space="preserve">30. </s>
            <s xml:id="echoid-s571" xml:space="preserve">To demonſtrate this, draw the Line A B
              <lb/>
            perpendicular to the Baſe Line; </s>
            <s xml:id="echoid-s572" xml:space="preserve">O V perpendi-
              <lb/>
            cular to the Horizontal Line; </s>
            <s xml:id="echoid-s573" xml:space="preserve">and A C, O H
              <lb/>
            perpendicular to the Tangent H C. </s>
            <s xml:id="echoid-s574" xml:space="preserve">All theſe
              <lb/>
            Perpendiculars will cut the Lines to which they
              <lb/>
            are perpendicular, in the Points wherein theſe
              <lb/>
            laſt touch the Circle L B C, or H V I. </s>
            <s xml:id="echoid-s575" xml:space="preserve">Like-
              <lb/>
            wiſe draw the Line A E from the given Point
              <lb/>
            A, to the Point E, wherein the Line H C cuts
              <lb/>
            the Baſe Line. </s>
            <s xml:id="echoid-s576" xml:space="preserve">Finally, draw O D, from the
              <lb/>
            Eye O to the Point D, wherein the ſaid Line
              <lb/>
            HC cuts the Horizontal Line.</s>
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