Gravesande, Willem Jacob 's, An essay on perspective

Page concordance

< >
Scan Original
71 32
72 33
73 34
74 35
75 36
76
77
78
79
80
81
82
83
84
85 37
86 38
87 39
88 40
89 41
90 42
91
92
93
94 43
95 44
96 45
97 46
98
99
100
< >
page |< < (18) of 237 > >|
    <echo version="1.0RC">
      <text xml:lang="en" type="free">
        <div xml:id="echoid-div60" type="section" level="1" n="30">
          <p>
            <s xml:id="echoid-s537" xml:space="preserve">
              <pb o="18" file="0040" n="42" rhead="An ESSAY"/>
            and drawing a Line from the Point I to the
              <lb/>
            other Point of Diſtance; </s>
            <s xml:id="echoid-s538" xml:space="preserve">which, by its Inter-
              <lb/>
            ſection with E D, will give the Appearance of
              <lb/>
            the Point A.</s>
            <s xml:id="echoid-s539" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div61" type="section" level="1" n="31">
          <head xml:id="echoid-head33" xml:space="preserve">
            <emph style="sc">Method</emph>
          II.</head>
          <p>
            <s xml:id="echoid-s540" xml:space="preserve">26. </s>
            <s xml:id="echoid-s541" xml:space="preserve">γ is the Horizontal Plane, X the Perſpe-
              <lb/>
            ctive Plane, Z the Geometrical Plane, O the Eye,
              <lb/>
            D C the Horizontal Line, B E the Baſe Line, and
              <lb/>
            A the given Point.</s>
            <s xml:id="echoid-s542" xml:space="preserve"/>
          </p>
          <note position="left" xml:space="preserve">Fig. 8.</note>
        </div>
        <div xml:id="echoid-div62" type="section" level="1" n="32">
          <head xml:id="echoid-head34" xml:space="preserve">
            <emph style="sc">Operation</emph>
          .</head>
          <p>
            <s xml:id="echoid-s543" xml:space="preserve">Draw a Line from the Point A, to the Eye O, cut-
              <lb/>
            ting the Baſe Line in the Point B, and the Horizon-
              <lb/>
            tal Line in the Point C: </s>
            <s xml:id="echoid-s544" xml:space="preserve">Then aſſume B E in the
              <lb/>
            Baſe Line, equal to B A; </s>
            <s xml:id="echoid-s545" xml:space="preserve">and C D in the Hori-
              <lb/>
            zontal Line, equal to C O; </s>
            <s xml:id="echoid-s546" xml:space="preserve">and join the Points
              <lb/>
            E and D, by a Line cutting the Line A O in
              <lb/>
            the Point a; </s>
            <s xml:id="echoid-s547" xml:space="preserve">which will be the Appearance
              <lb/>
            ſought.</s>
            <s xml:id="echoid-s548" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div63" type="section" level="1" n="33">
          <head xml:id="echoid-head35" xml:space="preserve">
            <emph style="sc">Demonstration</emph>
          .</head>
          <p>
            <s xml:id="echoid-s549" xml:space="preserve">27. </s>
            <s xml:id="echoid-s550" xml:space="preserve">The Triangle O D C in the Horizontal
              <lb/>
            Plane, is ſimilar to the Triangle A B E in the
              <lb/>
            Geometrical Plane; </s>
            <s xml:id="echoid-s551" xml:space="preserve">and conſequently A B is pa-
              <lb/>
            rallel to O C, and A E to O D. </s>
            <s xml:id="echoid-s552" xml:space="preserve">But the Appear-
              <lb/>
            ance of A muſt be in the Lines B C, and E D;</s>
            <s xml:id="echoid-s553" xml:space="preserve">
              <note symbol="*" position="left" xlink:label="note-0040-02" xlink:href="note-0040-02a" xml:space="preserve">
                <unsure/>
              13.</note>
            and therefore it will be in a, their Interſection.</s>
            <s xml:id="echoid-s554" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div65" type="section" level="1" n="34">
          <head xml:id="echoid-head36" xml:space="preserve">
            <emph style="sc">Remarks</emph>
          .</head>
          <p>
            <s xml:id="echoid-s555" xml:space="preserve">28. </s>
            <s xml:id="echoid-s556" xml:space="preserve">If the Place wherein the Eye ought to be in
              <lb/>
            the Horizontal Plane be not known, but the Point
              <lb/>
            of Sight is; </s>
            <s xml:id="echoid-s557" xml:space="preserve">then, to find the Place of the Eye,
              <lb/>
            a Perpendicular muſt be rais’d from the Point </s>
          </p>
        </div>
      </text>
    </echo>
Impressum