Galilei, Galileo, Mechanics, 1665

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              <s>
                <pb xlink:href="070/01/016.jpg" pagenum="286"/>
              than the Diſtance A C; that is, as the Force is leſſe than the
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              Weight.</s>
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              <s>Theſe Principles being declared, we will paſſe to the Contem­
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              plation of Pullies, the compoſition and ſtructure of which, together
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              with their uſe, ſhall be deſcribed by us. </s>
              <s>And firſt let us ſuppoſe the
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                <arrow.to.target n="marg1109"/>
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              ^{*} Little Pulley A B C, made of Mettall or hard Wood, voluble a­
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              bout it's Axis which paſſeth thorow it's Center D, and about this
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                <figure id="id.070.01.016.1.jpg" xlink:href="070/01/016/1.jpg" number="11"/>
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              Pulley let the Rope E A B C be put,
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              at one end of whichlet the Weight E
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              hang, and at the other let us ſuppoſe
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              the Force F. </s>
              <s>I ſay, that the Weight
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              being ſuſtained by a Force equall to
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              it ſelf in the upper Nut or Pulley
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              A B C, bringeth ſome benefit, as the
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              moving or ſuſtaining of the ſaid
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              Weight with the Force placed in F:
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              For if we ſhall underſtand, that from
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              the Center D, which is the place of the Fulciment, two Lines be
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              drawn out as far as the Circumference of the Pulley in the points
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              A and C, in which the pendent Cords touch the Circumference, we
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              ſhall have a Ballance of equal Arms which determine the Diſtance
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              of the two Suſpenſions from the Center and Fulciment D: Where­
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              upon it is manifeſt, that the Weight hanging at A cannot be ſuſtain­
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              ed by a leſſer Weight hanging at G, but by one equal to it; ſuch
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              is the nature of equal Weights hanging at equal Diſtances. </s>
              <s>And
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              although in moving downwards, the Force F cometh to turn about
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              the Pulley A B C, yet there followeth no alteration of the Alti­
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              tude or Reſpect, that the Weight and Force have unto the two
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              Diſtances A D and D C, nay, the Pulley encompaſſed becometh a
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              Ballance equal to A C, but perpetuall. </s>
              <s>Whence we may learn,
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              how childiſhly
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              Ariſtotle
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              deceiveth himſelf, who holds, that by making
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              the ſmall Pulley A B C bigger, one might draw up the Weight with
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              a leſſer Force; he conſidering that upon the enlargement of the
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              ſaid Pulley, the Diſtance D C encreaſed, but not conſidering that
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              there was as great an encreaſe of the other Diſtance of the Weight,
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              that is, the other Semidiameter D A. </s>
              <s>The benefit therefore that may
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              be drawn from the Inſtrument above ſaid, is nothing at all as to the
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              diminution of the labour: and if any one ſhould ask how it hap­
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              pens, that on many occaſions of raiſing Weights, this means is made
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              uſe of to help the Axis, as we ſee, for example, in drawing up the
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              Water of Wells; it is anſwered, that that is done, becauſe that
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              by this means the manner of employing the Force is found more
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              commodious: for being to pull downwards, the proper Gravity of
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              our Arms and other parts help us, whereas if we were to draw
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              the fame Weight upwards with a meer Rope, by the ſole ſtrength </s>
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