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

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              it was manifeſt that the riſing of the Lake cauſed by the rain, was
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              to a hair thoſe four fingers breadth that I had judged it to be.
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              </s>
              <s>Two dayes after I had another bout with the Ingeneer, and re­
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              lated to him the whole buſineſs, to which he knew not what to
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              anſwer.</s>
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              <s>
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              * A Coyn of Pope
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                <emph type="italics"/>
              Julius
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              worth ſix
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              pence.</s>
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              <s>Now the two difficulties which I thought of, able to impede
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              my concluſion, were theſe following: Firſt, I conſidered that
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              it might be, that the Wind blowing from the ſide where the
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              Sluice ſtood, to the Lake-ward; the mole and maſs of the Wa­
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              ter of the Lake might be driven to the contrary ſhore; on which
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              the Water riſing, it might be fallen at the mouth of the Emiſſa­
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              ry, and ſo the obſervation might be much obſcured. </s>
              <s>But this
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              difficulty wholly vaniſhed by reaſon of the Aires great tranqui­
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              lity; which it kept at that time, for no Wind was ſtirring on any
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              ſide, neither whilſt it rained, nor afterwards.</s>
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              <s>The ſecond difficulty which put the riſing in doubt, was, That
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              having obſerved in
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              Florence,
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              and elſewhere, thoſe Ponds into
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              which the rain-water, falling from the houſe, is conveyed
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              through the Common-ſhores: And that they are not thereby
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              ever filled, but that they ſwallow all that abundance of water,
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              that runs into them by thoſe conveyances which ſerve them with
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              water; inſomuch that thoſe conveyances which in time of
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              drought maintain the Pond, when there comes new abundance
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              of water into the Pond, they drink it up, and ſwallow it: A like
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              effect might alſo fall out in the Lake, in which there being many
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              veins (as it is very likely) that maintain and feed the Lake; theſe
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              veins might imbibe the new addition of the Rain-water, and ſo
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              by that means annuall the riſing; or elſe diminiſh it in ſuch ſort, as
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              to render it inobſervable. </s>
              <s>But this difficulty was eaſily reſolved
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              by conſidering my Treatiſe of the meaſure of Running-Waters;
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              foraſmuch as having demonſtrated, that the abatement of a Lake
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              beareth the reciprocal proportion to the velocity of the Emiſſa­
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              ry, which the meaſure of the Section of the Emiſſary of the Lake,
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              hath to the meaſure of the ſurface of the Lake: making the
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              calculation and account, though in groſs; by ſuppoſing that its
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              veins were ſufficiently large, and that the velocity in them were
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              notable in drinking up the water of the Lake; yet I found never­
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              theleſs, that many weeks and moneths would be ſpent in drink­
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              ing up the new-come abundance of water by the rain, ſo that
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              I reſted ſure, that the riſing would enſue, as in effect it did.</s>
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              <s>And becauſe many of accurate judgement, have again cauſed
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              me to queſtion this riſing, ſetting before me, that the Earth be­
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              ing parched by the great drought, that had ſo long continued, it
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              might be, that that Bank of Earth which environed the brink of
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              the Lake, being dry, and imbibing great abundance of Water </s>
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          </chap>
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