Salusbury, Thomas, Mathematical collections and translations (Tome I), 1667

Table of figures

< >
[Figure 161]
[Figure 162]
[Figure 163]
[Figure 164]
[Figure 165]
[Figure 166]
[Figure 167]
[Figure 168]
[Figure 169]
[Figure 170]
[Figure 171]
[Figure 172]
[Figure 173]
[Figure 174]
[Figure 175]
[Figure 176]
[Figure 177]
[Figure 178]
[Figure 179]
[Figure 180]
[Figure 181]
[Figure 182]
[Figure 183]
[Figure 184]
[Figure 185]
[Figure 186]
[Figure 187]
[Figure 188]
[Figure 189]
[Figure 190]
< >
page |< < of 701 > >|
    <archimedes>
      <text>
        <body>
          <chap>
            <p type="main">
              <s>
                <pb xlink:href="040/01/700.jpg" pagenum="8"/>
              fingers, did not yield to follow him that would have forceably
                <lb/>
              drawn it from between them, reſiſted, becauſe it was ſtayed by a
                <lb/>
              double compreſſion, ſince the upper finger preſt no leſſe againſt
                <lb/>
              the nether, than it preſſed againſt that. </s>
              <s>And there is no queſtion,
                <lb/>
              that if of theſe two preſſures, one alone might be retained, there
                <lb/>
              would remain half of that Reſiſtance, which depended conjunctive­
                <lb/>
              ly on them both: but becauſe you cannot with removing,
                <emph type="italics"/>
              v.g.
                <emph.end type="italics"/>
              the
                <lb/>
              upper finger take away its preſſion, without taking away the other
                <lb/>
              part alſo; it will be neceſſary by ſome new Artifice to retain one
                <lb/>
              of them, and to find a way that the ſame thread may compreſſe it
                <lb/>
              ſelf againſt the finger or other ſolid body upon which it is put; and
                <lb/>
              this is done by winding the ſame thread about the Solid. </s>
              <s>For the
                <lb/>
              better underſtanding whereof, I will briefly give it you in Figure;
                <lb/>
              and let
                <emph type="italics"/>
              A B
                <emph.end type="italics"/>
              and C
                <emph type="italics"/>
              D
                <emph.end type="italics"/>
              be two Cilinders, and between them let there
                <lb/>
              be diſtended the thread
                <emph type="italics"/>
              E F,
                <emph.end type="italics"/>
              which for greater plainneſſe I will
                <lb/>
              repreſent to be a ſmall Cord: there is no doubt but that the two
                <lb/>
              Cylinders being preſſed hard one againſt the other, the Cord
                <lb/>
                <emph type="italics"/>
              E F
                <emph.end type="italics"/>
              pulled by the end
                <emph type="italics"/>
              F
                <emph.end type="italics"/>
              will Reſiſt no ſmal force before
                <lb/>
              it will ſlip from between the two Solids compreſſing it: but if
                <lb/>
              we remove one of them, though the Cord
                <lb/>
                <figure id="id.040.01.700.1.jpg" xlink:href="040/01/700/1.jpg" number="53"/>
                <lb/>
              continue touching the other, yet ſhall it not
                <lb/>
              by ſuch contact be hindered from ſlipping
                <lb/>
              away. </s>
              <s>But if holding it faſt, though but
                <lb/>
              gently in the point A, towards the top of the
                <lb/>
              Cylinder, we wind, or belay it about the
                <lb/>
              ſame ſpirally in A F L O T R, and pull it by
                <lb/>
              the end R: it is manifeſt, that it will begin
                <lb/>
              to preſſe the Cylinder, and if the windings
                <lb/>
              and wreathes be many, it ſhall in its effectual
                <lb/>
              drawing alwaies preſſe it ſo much the ſtrai­
                <lb/>
              ter about the Cylinder: and by multiplying
                <lb/>
              the wreathes if you make the contact longer,
                <lb/>
              and conſequently more invincible, the more
                <lb/>
              difficult ſtill ſhall it be to withdraw the
                <lb/>
              Cord, and make it yield to the force that
                <lb/>
              pulls it. </s>
              <s>Now who ſeeth not, that the ſame
                <lb/>
              Reſiſtance is in the threads, which with many thouſand ſuch
                <lb/>
              twinings ſpin the thick Cord? </s>
              <s>Yea, the ſtreſſe of ſuch twiſting
                <lb/>
              bindeth with ſuch Tenacity, that a few Ruſhes, and of no great
                <lb/>
              length, (ſo that the wreaths and windings are but few where­
                <lb/>
              with they entertwine) make very ſtrong bands, called, as I take it,
                <lb/>
                <arrow.to.target n="marg1002"/>
                <lb/>
              ^{*} Thum-ropes.</s>
            </p>
            <p type="margin">
              <s>
                <margin.target id="marg1002"/>
              * Fuſta.</s>
            </p>
            <p type="main">
              <s>SAGR. </s>
              <s>Your Diſcourſe hath removed the wonder out of my
                <lb/>
              mind at two effects, whereof I did not well underſtand the rea­
                <lb/>
              ſon; One was to ſee, how two, or at the moſt three twines of the </s>
            </p>
          </chap>
        </body>
      </text>
    </archimedes>