Alberti, Leone Battista, Architecture, 1755

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              <s>
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              this being ſo, this Part ought of the whole
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              Structure to be beſt fortified againſt the
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              Violence of the Waters; and nothing will
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              conduce more to this, than to make the Pile­
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              work deep and broad every Way, and eſpeci­
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              ally at the Stern, that if any Accidents ſhould
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              carry away any of the Piles, there may be enow
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              leſt to ſuſtain the Weight of the Pier. </s>
              <s>It will
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              be alſo extremely proper to begin your Foun­
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              dation at the upper Part of the Channel, and
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              to make it with an eaſy Deſcent, that the
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              Water which runs over it may not fall upon
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              it violently as into a Precipice, but glide over
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              gently, with an eaſy Slope; becauſe the Water
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              that ruſhes down precipitately, routs up the
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              Bottom, and ſo being made ſtill rougher carries
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              away every Thing that it can looſen, and is
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              every Moment undermining the Work.</s>
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              <s>BUILD the Piers of the biggeſt and longeſt
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              Stones, and of ſuch as in their Nature are beſt
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              adapted for ſupporting of Froſts, and as do
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              not decay in Water, nor are eaſily ſoftened by
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              any Accident, and will not crack and ſplit
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              under a great Weight; and build them ex­
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              actly according to the Square, Level and Plum­
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              line, omitting no Sort of Ligature Length­
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              ways, and placing the Stones Breadth-ways in
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              alternate Order, ſo as to be a Binding one to
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              another; abſolutely rejecting any ſtuffing with
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              ſmall Pieces of Stone. </s>
              <s>You muſt alſo faſten
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              your Work with a good Number of Braſs
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              Cramps and Pins, ſo well fitted in, that the
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              Joynts of the Structure may not ſeparate, but
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              be kept tight and firm. </s>
              <s>Raiſe both the Fronts
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              of the Building angular, both Head and Stern,
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              and let the Top of the Pier be ſure to be
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              higher than the fulleſt Tide; and let the Thick­
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              neſs of the Pier be one fourth of the Heighth
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              of the Bridge. </s>
              <s>There have been ſome that
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              have not terminated the Head and Stern of
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              their Piers with an Angle, but with an half
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              Circle; induced thereto, I ſuppoſe, by the
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              Beautifulneſs of that Figure. </s>
              <s>But though I
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              have ſaid elſewhere, that the Circle has the
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              ſame Strength as an Angle, yet here I approve
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              better of an Angle, provided it be not ſo ſharp
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              as to be broken and defaced by every little Acci­
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              dent: Nor am I altogether diſpleaſed with thoſe
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              which end in a Curve, provided it be very much
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              lengthened out, and not left ſo obtuſe as to re­
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              ſiſt the Force and Weight of the Water. </s>
              <s>The
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              Angle of the Pier is of a good Sharpneſs, if it
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              is three Quarters of a Right Angle, or if you
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              like it better, you may make it two thirds.
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              </s>
              <s>And thus much may ſuffice as to the Piers. </s>
              <s>If
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              the Nature of your Situation is ſuch, that the
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              Sides or Banks of the Shore are not as you
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              could wiſh; make them good in the ſome Man­
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              ner as you build your Piers, and indeed make
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              other Piers upon the Shore, and turn ſome
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              Arches even upon the dry Ground; to the
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              Intent, that if in Proceſs of Time, by the con­
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              tinual waſhing of the Water, and the Force of
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              the Tides, any Part of the Bank ſhould be
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              carried away, your Paſſage may ſtill be pre­
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              ſerved ſafe, by the Production of the Bridge
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              into the Land. </s>
              <s>The Arches ought upon all
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              Accounts, and particularly becauſe of the con­
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              tinual violent ſhaking and Concuſſion of Carts
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              and other Carriages, to be extreamly ſtout and
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              ſtrong. </s>
              <s>Beſides, as ſometimes you may be
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              obliged to draw immenſe Weights over them,
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              ſuch as a Coloſſus, an Obelisk or the like; you
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              ſhould provide againſt the Inconvenience which
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              happened to
                <emph type="italics"/>
              Scaurus,
                <emph.end type="italics"/>
              who when he was re­
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              moving that great Boundary Stone, alarmed all
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              the publick Officers, upon Account of the
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              Miſchief that might enſue. </s>
              <s>For theſe Reaſons,
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              a Bridge both in its Deſign, and in its whole
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              Execution, ſhould be well fitted to bear the
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              continual and violent Jars which it is to re­
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              ceive from Carriages. </s>
              <s>That Bridges ought to
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              be built of very large and ſtout Stones, is very
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              manifeſt by the Example of an Anvil, which,
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              if is large and heavy, ſtands the Blows of the
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              Hammer unmoved; but if it is light, rebounds
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              and trembles at every Stroke. </s>
              <s>We have al­
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              ready ſaid, that all vaulted Work conſiſts of
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              Arches and Stuffing, and that the ſtrongeſt of
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              all Arches is the Semi-circle. </s>
              <s>But if by the
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              Diſpoſition of the Piers, the Semi-circle ſhould
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              riſe ſo high as to be inconvenient, we may
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              make uſe of the Scheme Arch, only taking
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              Care to make the laſt Piers on the Shore the
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              ſtronger and thicker. </s>
              <s>But whatever Sort of
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              Arch you vault your Bridge with, it muſt be
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              built of the hardeſt and largeſt Stones, ſuch as
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              you uſe in your Piers; and there ſhould not
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              be a ſingle Stone in the Arch but what is in
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              Thickneſs at leaſt one tenth Part of the Chord
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              of that Arch; nor ſhould the Chord itſelf be
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              longer than ſix Times the Thickneſs of the
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              Pier, nor ſhorter than four Times. </s>
              <s>The Stones
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              alſo ſhould be ſtrongly faſtened together with
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              Pins and Cramps of Braſs. </s>
              <s>And the laſt Wedge,
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              which is called the Key-ſtone, ſhould be cut
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              according to the Lines of the other Wedges,
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              but left a ſmall Matter bigger at the Top, ſo
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              that it may not be got into its Place without
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              ſome Strokes of a light Beetle; which will </s>
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