Gravesande, Willem Jacob 's, An essay on perspective

Table of figures

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[21] Fig. 21.I X f T L B N A C l M E F
[22] page 38Plate 10.Fig. 22.V F I N a G H M P D E B C L A
[23] Fig. 23.O F I H a G D E B C L A M
[24] Fig. 24.@ o f X a e A
[25] page 42Plate 11.Fig. 25.S F V M I N P H a L D E G C A B
[26] Fig. 26.Fig. 27.S V P Q R n l g h G H B N I A C M L
[27] page 46Plate 12.Fig. 28.
[28] Fig. 29.F S V q q q E L p p p I G H q D P n n n T R m m m C B Q A
[29] Fig. 30.O X E L N M G Z Y D
[30] Fig. 31.f 3 c l n m g 4
[31] page 48.Plate 13.Fig. 32.V S R L P B D Q T M I F A E Y C G O H Z N
[32] page 52.Plate. 14.Fig. 34D C F G A B H L E
[33] Fig. 33S X 8 1 h 6 g 3 z q 9 m 2 4 m a 5 Y
[34] Fig. 35O M D P T Q R m p q B A S C
[35] page 56.Plate. 15F H O Z D G
[36] Fig. 36T N M L a R Q E I A C P B
[37] Fig. 37F S V T I E M A N X P C B
[38] page 58.Plate. 16Fig. 39Fig. 38F Q O p l r s 1 2 3 4 G
[39] page 60.Plate. 17F V
[40] Fig. 40c θ b e a F G H I K L A B E C D
[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
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            from the Eye O upon the Baſe Line, the Appear-
              <lb/>
            ances of all Lines paſſing through S, will be
              <lb/>
            perpendicular to the Baſe Line; </s>
            <s xml:id="echoid-s709" xml:space="preserve">but the ſaid
              <lb/>
            Point S is the Station Point. </s>
            <s xml:id="echoid-s710" xml:space="preserve">Whence, &</s>
            <s xml:id="echoid-s711" xml:space="preserve">c.</s>
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        <div xml:id="echoid-div93" type="section" level="1" n="53">
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            <emph style="sc">Problem</emph>
          II.</head>
          <p style="it">
            <s xml:id="echoid-s713" xml:space="preserve">42. </s>
            <s xml:id="echoid-s714" xml:space="preserve">To throw a Line in the Geometrical Plane
              <lb/>
            into Perſpective.</s>
            <s xml:id="echoid-s715" xml:space="preserve"/>
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          <p>
            <s xml:id="echoid-s716" xml:space="preserve">It has been ſhewn , that to have the
              <note symbol="*" position="left" xlink:label="note-0052-01" xlink:href="note-0052-01a" xml:space="preserve">21.</note>
            ſentation of a right Line, the Perſpective of
              <lb/>
            the Extremes of the ſaid Line, need only be
              <lb/>
            found; </s>
            <s xml:id="echoid-s717" xml:space="preserve">and although it is difficult to find
              <note symbol="*" position="left" xlink:label="note-0052-02" xlink:href="note-0052-02a" xml:space="preserve">22.</note>
            Repreſentation of two Points, nevertheleſs I
              <lb/>
            ſhall ſhew here how to find more eaſy the Re-
              <lb/>
            preſentation of a Line in ſome Caſes.</s>
            <s xml:id="echoid-s718" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s719" xml:space="preserve">1. </s>
            <s xml:id="echoid-s720" xml:space="preserve">Let A B be a Line parallel to the Baſe
              <lb/>
              <note position="left" xlink:label="note-0052-03" xlink:href="note-0052-03a" xml:space="preserve">Fig. 13.</note>
            Line: </s>
            <s xml:id="echoid-s721" xml:space="preserve">To draw the Repreſentation of which,
              <lb/>
            having firſt found the Point a the Appearance
              <lb/>
            of A, one of the Ends of the given Line; </s>
            <s xml:id="echoid-s722" xml:space="preserve">af-
              <lb/>
            terwards through that Appearance, draw a Pa-
              <lb/>
            rallel to the Baſe Line; </s>
            <s xml:id="echoid-s723" xml:space="preserve">then the Line B O,
              <lb/>
            drawn from B to the Eye O, will cut the ſaid
              <lb/>
            parallel in the Point b, and b a will be the Re-
              <lb/>
            preſentation ſought.</s>
            <s xml:id="echoid-s724" xml:space="preserve"/>
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            <s xml:id="echoid-s725" xml:space="preserve">43. </s>
            <s xml:id="echoid-s726" xml:space="preserve">2. </s>
            <s xml:id="echoid-s727" xml:space="preserve">Let C G be a Line, which continued
              <lb/>
            out, cuts the baſe Line in E. </s>
            <s xml:id="echoid-s728" xml:space="preserve">Now to draw the
              <lb/>
            Appearance thereof; </s>
            <s xml:id="echoid-s729" xml:space="preserve">through the Eye O, draw a
              <lb/>
            Line parallel thereto, cutting the Horizontal
              <lb/>
            Line in D, and joyn the Points E and D, by
              <lb/>
            the Line E D, which cut in the Points c and g,
              <lb/>
            by Lines drawn from C and G to the Eye; </s>
            <s xml:id="echoid-s730" xml:space="preserve">then
              <lb/>
            the Part c g of the Line E D, is the Appearance
              <lb/>
            ſought.</s>
            <s xml:id="echoid-s731" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div96" type="section" level="1" n="54">
          <head xml:id="echoid-head56" xml:space="preserve">
            <emph style="sc">Remark</emph>
          .</head>
          <p>
            <s xml:id="echoid-s732" xml:space="preserve">If the Lines G O and C O cut E D very ob-
              <lb/>
            liquely, and ſo their Interſection cannot be </s>
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