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

List of thumbnails

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