Castelli, Benedetto, Of the mensuration of running waters, 1661

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              more than it did at the level AF, it would riſe yet more above
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              the ſaid level A F; although that the ſelf ſame quantity of water
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              runneth all the while. </s>
              <s>By the above-named ſolid Principle I
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              reſolve extravagant Problems in my Treatiſe, and aſſign the Rea­
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              ſons of admirable effects of Running Waters: But as for what
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              concerneth our purpoſe of the
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              Pontine Fenns,
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              we have the Cau­
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              ſes very plain and clear; for which, by the trampling of Cattle
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              which paſs thorow the
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              Draining River,
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              the waters abate ſo nota­
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              bly, that it is as it were a miracle for thoſe Reeds, Flags, and
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              Weeds that ſpring up, encreaſe, and ſpread all over the River,
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              ſtop and impede that velocity of the waters which they would
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              have by means of their declivity. </s>
              <s>But that paſſage of thoſe Beaſts,
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              treading down thoſe Weeds unto the bottom of the River, in ſuch
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              ſort, as that they no longer hinder the Current of the Water;
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              and the ſame Waters increaſing in their courſe, they do dimi­
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              niſh in meaſure and height; and by this meanes the Ditches of the
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              Plains empty into the ſame ſucceſsfully, and leave them free
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              from Waters, and Drained. </s>
              <s>But theſe Weeds in a ſhort
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              time ſprouting up anew, and raiſing their ſtalkes thorow the
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              body of the Waters, they reduce things to the ſame evil
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              ſtate, as before, retarding the velocity of the Water, ma­
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              king it to increaſe in height, and perhaps do occaſion grea­
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              ter miſchiefs; ſeeing that thoſe many knots which each plant
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              ſhoots forth, begets a greater multitude of Stalks, which much
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              more incumbering the Water of the River, are a greater impe­
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              diment unto its velocity, and conſequently make the height
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              of the waters to encreaſe ſo much the more, and do more miſchief
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              than before.</s>
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              <s>Another head to which theſe harms may be reduced, but pro­
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              ceeding from the ſame Root, which hath a great part in this
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              diſorder, is the impediment of thoſe Wears in the River which
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              are made by heightning the bed of the ſame, for placing of fiſh­
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              ing-nets; of which
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              Piſcaries
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              I reckoned above ten, when I made
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              a voyage thorow thoſe waters to
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              Sandolo.
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              And theſe Fiſhing­
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              Wears are ſuch impediments, that ſome one of them makes the
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              water of the River in the upper part to riſe half a Palm, and
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              ſometimes a whole Palm, and more; ſo that when they are all
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              gathered together, theſe impediments amount to more than ſeven,
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              or poſſibly than eight Palms.</s>
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              <s>There concurreth for a third moſt Potent Cauſe of the waters
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              continuing high in the evacuating, or Draining Chanel, and con­
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              ſequently on the Plains; The great abundance of water that iſſu­
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              eth from
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              Fiume Siſto,
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              the waters of which do not keep within its
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              Banks when they are abundant; but encreaſing above its Chanel,
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              they unite with thoſe of the Evacuator, and diſperſing thorow </s>
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