Gravesande, Willem Jacob 's, An essay on perspective

List of thumbnails

< >
181
181 		182
182 (89)
183
183 (90) 		184
184 (91)
185
185 (92) 		186
186
187
187 		188
188
189
189 (93) 		190
190 (94)
< >
page |< < (94) of 237 > >|
    <echo version="1.0RC">
      <text xml:lang="en" type="free">
        <div xml:id="echoid-div342" type="section" level="1" n="185">
          <p>
            <s xml:id="echoid-s2117" xml:space="preserve">
              <pb o="94" file="0164" n="190" rhead="An ESSAY"/>
            Rulers, keeping all the Threads tight, ſo that
              <lb/>
            the two Threads fix’d in the Points C and F,
              <lb/>
            croſs each other in the Point A; </s>
            <s xml:id="echoid-s2118" xml:space="preserve">and then the
              <lb/>
            Point a, wherein the two other Threads croſs
              <lb/>
            each other, is the Perſpective ſought. </s>
            <s xml:id="echoid-s2119" xml:space="preserve">And in
              <lb/>
            this Manner may the Repreſentations of any
              <lb/>
            Number of Points be ſound.</s>
            <s xml:id="echoid-s2120" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div343" type="section" level="1" n="186">
          <head xml:id="echoid-head200" xml:space="preserve">
            <emph style="sc">Demonstration</emph>
          .</head>
          <p>
            <s xml:id="echoid-s2121" xml:space="preserve">118. </s>
            <s xml:id="echoid-s2122" xml:space="preserve">The Triangle D a E, is ſimilar to the
              <lb/>
            Triangle C A F: </s>
            <s xml:id="echoid-s2123" xml:space="preserve">And becauſe all the Triangles
              <lb/>
            formed for finding the Repreſentations of diffe-
              <lb/>
            rent Points, have the ſame Baſes D E and C F,
              <lb/>
            which are between themſelves, as the Eye’s Di-
              <lb/>
            ſtance from the perſpective Plane, to its Diſtance
              <lb/>
            from the Geometrical Plane; </s>
            <s xml:id="echoid-s2124" xml:space="preserve">whence their Ver-
              <lb/>
            tices form ſimilar Figures, whoſe correſpondent
              <lb/>
            Lines are in the ſame Proportion; </s>
            <s xml:id="echoid-s2125" xml:space="preserve">and which
              <lb/>
            conſequently , are the Appearances ſought.</s>
            <s xml:id="echoid-s2126" xml:space="preserve"/>
          </p>
          <note symbol="*" position="left" xml:space="preserve">8, 9.</note>
        </div>
        <div xml:id="echoid-div344" type="section" level="1" n="187">
          <head xml:id="echoid-head201" xml:space="preserve">
            <emph style="sc">Remarks</emph>
          .</head>
          <p>
            <s xml:id="echoid-s2127" xml:space="preserve">It will be convenient to have the two Threads
              <lb/>
            P E, and M D of one Colour, and the two
              <lb/>
            Threads Q F, and C N of another.</s>
            <s xml:id="echoid-s2128" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div345" type="section" level="1" n="188">
          <head xml:id="echoid-head202" xml:space="preserve">
            <emph style="sc">Prob</emph>
          . VI.</head>
          <p style="it">
            <s xml:id="echoid-s2129" xml:space="preserve">119. </s>
            <s xml:id="echoid-s2130" xml:space="preserve">To find the Repreſentations of any Number
              <lb/>
            of Lines, equal and perpendicular to the Geometri-
              <lb/>
            cal Plane.</s>
            <s xml:id="echoid-s2131" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s2132" xml:space="preserve">Let C D E F G I H, be the Points denoted
              <lb/>
              <note position="left" xlink:label="note-0164-02" xlink:href="note-0164-02a" xml:space="preserve">Fig. 64.</note>
            with the ſame Letters in the precedent Figure,
              <lb/>
            as alſo let P Q and M N be the Rulers: </s>
            <s xml:id="echoid-s2133" xml:space="preserve">More-
              <lb/>
            over, let B be the Point, wherein a </s>
          </p>
        </div>
      </text>
    </echo>
Impressum