Alberti, Leone Battista, Architecture, 1755

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              <s>
                <pb xlink:href="003/01/093.jpg" pagenum="76"/>
              that the Buildings there did not joyn one to
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              ano her.
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              Plato,
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              on the contrary, is ſo far from
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              approving of thoſe Separations, that he would
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              have the Houſes all cloſe contiguous, and
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              that the joyning together of their Walls ſhould
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              make a Wall to the City.</s>
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            <p type="head">
              <s>CHAP. VI.</s>
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              <s>
                <emph type="italics"/>
              Of Bridges both of Wood and Stone, their proper Situation, their Peers,
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              Arches, Angles, Feet, Key-ſtones, Cramps, Pavements, and Slopes.
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              </s>
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            <p type="main">
              <s>The Bridge, no doubt, is a main Part
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              of the Street; nor is every Part of the
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              City proper for a Bridge; for beſides that it
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              is inconvenient to place it in a remote Corner
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              of the Town, where it can be of Uſe but to
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              few, and that it ought to be in the very Heart
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              of the City, to lie at hand for every body; it
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              ought certainly to be contrived in a Place
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              where it may eaſily be erected, and without
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              too great an Expence, and where it is likely
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              to be the moſt durable. </s>
              <s>We ſhould therefore
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              chuſe a Ford where the Water is not too deep;
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              where the Shore is not too ſteep; which is
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              not uncertain and moveable, but conſtant
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              and laſting. </s>
              <s>We ſhould avoid all Whirl­
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              pools, Eddies, Gulphs, and the like Inconve­
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              niences common in bad Rivers. </s>
              <s>We ſhould
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              alſo moſt carefully avoid all Elbows, where the
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              Water takes a Turn; for very many Reaſons;
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              the Banks in ſuch Places being very liable to
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              be broken, as we ſee by Experience, and be­
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              cauſe Pieces of Timber, Trunks of Trees, and
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              the like, brought down from the Country by
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              Storms and Floods, cannot ſwim down ſuch
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              Elbows in a ſtrait Line, but turn aſlant, meet
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              and hinder one another, and lodging againſt
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              the Piles grow into a great Heap, which ſtops
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              up the Arches, and with the additional
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              Weight of the Water at length quite breaks
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              them down.</s>
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            <p type="main">
              <s>OF Bridges, ſome are of Stone, others of
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              Wood. </s>
              <s>We ſhall ſpeak firſt of thoſe which
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              are of Wood, as the moſt eaſy of Execution;
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              next we ſhall treat of thoſe which are built of
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              Stone. </s>
              <s>Both ought to be as ſtrong as poſſible;
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              that therefore which is built of Wood, muſt
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              be fortified with a good Quantity of the
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                <arrow.to.target n="marg11"/>
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              ſtrongeſt Timbers. </s>
              <s>We cannot give a better
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              Example of this Sort of Bridges than that built
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              by
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              fulius Cæſar,
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              which he gives us a Deſcrip­
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              tion of himſelf, as follows: He faſtened to­
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              gether two Timbers, leaving a Diſtance be­
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              tween them of two Foot; their Length was
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              proportioned to the Depth of the River, and
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              they were a Foot and an half thick, and cut
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              ſharp at the Ends. </s>
              <s>Theſe he let down into
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              the River with Cranes, and drove them well in
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              with a Sort of Rammers, not perpendicularly
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              down like Piles, but ſlanting upwards, and
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              giving Way according to the Current of the
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              River. </s>
              <s>Then, oppoſite to theſe, he drove in
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              two others, faſtened together in the ſame Man­
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              ner, with a Diſtance between them at Bottom
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              of forty Foot, ſlanting contrary to the Force
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              and Current of the Stream. </s>
              <s>When theſe were
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              thus fixed, he laid acroſs from one to the other,
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              Beams of the Thickneſs of two Foot, which
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              was the Diſtance left between the Timbers
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              drove down; and faſtened theſe Beams at the
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              End, each with two Braces, which being
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              bound round and faſtened of oppoſite Sides,
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              the Strength of the whole Work was ſo great
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              and of ſuch a Nature, that the greatcr the
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              Force of Water was which bore againſt it,
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              the cloſer and firmer the Beams united. </s>
              <s>Over
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              theſe other Beams were laid acroſs and faſtened
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              to them, and a Floor, as we may call it, made
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              over them with Poles and Hurdles. </s>
              <s>At the
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              ſame Time, in the lower Part of the River,
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              below the Bridge, other Timbers, or ſloping
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              Piles, were driven down, which being faſtened
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              to the reſt of the Structure, ſhould be a Kind
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              of Buttreſs to reſiſt the Force of the Stream;
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              and other Piles were alſo driven in at a ſmall
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              Diſtance above the Bridge, and ſtanding ſome­
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              what above the Water, that if the Enemy
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              ſhould ſend Trunks of Trees, or Veſſels, down
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              the Stream, in order to break the Bridge, thoſe
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              Piles might receive and intercept their Vio­
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              lence, and prevent their doing any Prejudice
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              to the Work. </s>
              <s>All this we learn from
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              Cæſar.
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              Nor is it foreign to our Purpoſe to take Notice
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              of what is practiced at
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              Verona,
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              where they
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              pave their wooden Bridges with Bars of Iron,
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              eſpecially where the Wheels of Carts and Wag­
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              gons are to paſs. </s>
              <s>It remains now that we
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              </s>
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