Gravesande, Willem Jacob 's, An essay on perspective

Page concordance

< >
Scan Original
191 95
192 96
193
194
195
196
197
198
199 97
200 98
201 99
202 100
203
204
205
206 101
207 102
208 103
209 104
210 105
211 106
212 107
213 108
214 109
215 110
216 111
217 112
218 113
219 114
220 115
< >
page |< < (97) of 237 > >|
    <echo version="1.0RC">
      <text xml:lang="en" type="free">
        <div xml:id="echoid-div349" type="section" level="1" n="190">
          <p>
            <s xml:id="echoid-s2160" xml:space="preserve">
              <pb o="97" file="0171" n="199" rhead="on PERSPECTIVE."/>
            Points be found , the Repreſentations of
              <note symbol="*" position="right" xlink:label="note-0171-01" xlink:href="note-0171-01a" xml:space="preserve">109,
                <lb/>
              115, 117.</note>
            Shadows will be had.</s>
            <s xml:id="echoid-s2161" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div351" type="section" level="1" n="191">
          <head xml:id="echoid-head205" xml:space="preserve">CHAP. IX.</head>
          <p style="it">
            <s xml:id="echoid-s2162" xml:space="preserve">The Uſe of Perſpective in Dialling; </s>
            <s xml:id="echoid-s2163" xml:space="preserve">ſhewing
              <lb/>
            how to draw the Hour Lines upon any
              <lb/>
            Kind of Plane, by means of an Horizon-
              <lb/>
            tal Dial.</s>
            <s xml:id="echoid-s2164" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s2165" xml:space="preserve">PERSPECTIVE is not only uſeſul in
              <lb/>
            drawing, but likewiſe in other Parts of Ma-
              <lb/>
            thematicks, and principally in Dialling: </s>
            <s xml:id="echoid-s2166" xml:space="preserve">For if
              <lb/>
            the Extremity of the Style be conceived as the
              <lb/>
            Eye, and the Sun’s Rays as viſual Rays, all
              <lb/>
            poſſible Kinds of Dials may be drawn for the
              <lb/>
            ſame Latitude, by Means of an Horizontal Dial,
              <lb/>
            as we are now going to ſhew,</s>
          </p>
          <p>
            <s xml:id="echoid-s2167" xml:space="preserve">121. </s>
            <s xml:id="echoid-s2168" xml:space="preserve">Let A B C D be an Horizontal Dial
              <lb/>
            made for any given Latitude; </s>
            <s xml:id="echoid-s2169" xml:space="preserve">E F its Style, and
              <lb/>
              <note position="right" xlink:label="note-0171-02" xlink:href="note-0171-02a" xml:space="preserve">Fig. 65.</note>
            H I M L a Plane, upon which a Dial is to be
              <lb/>
            drawn. </s>
            <s xml:id="echoid-s2170" xml:space="preserve">Now if this Plane be ſo ſituated, that
              <lb/>
            the Extremity of its Style F G, coincides with
              <lb/>
            the Extremity of the Style of the Horizontal
              <lb/>
            Dial; </s>
            <s xml:id="echoid-s2171" xml:space="preserve">and if the Perſpective of one of the Hour
              <lb/>
            Lines of the Horizontal Dial A B C D, be found
              <lb/>
            upon the Plane H I M L, in conceiving the
              <lb/>
            Point F as the Eye, it is evident , that
              <note symbol="*" position="right" xlink:label="note-0171-03" xlink:href="note-0171-03a" xml:space="preserve">2.</note>
            Shadow of the Point F, will fall upon the ſaid
              <lb/>
            Perſpective, at the ſame Time that it falls
              <lb/>
            upon the Hour Line, whereof it is the Per-
              <lb/>
            ſpective; </s>
            <s xml:id="echoid-s2172" xml:space="preserve">and conſequently, the ſaid Shadow
              <lb/>
            will ſhew the ſame Hour upon the Plane H I M L,
              <lb/>
            that it ſhews upon the Horizontal Dial: </s>
            <s xml:id="echoid-s2173" xml:space="preserve"/>
          </p>
        </div>
      </text>
    </echo>
Impressum