Alberti, Leone Battista, Architecture, 1755
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              <s>CHAP. IX.</s>
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              Of the Girders of Stone, of the Ligament and Fortification of the Cornices,
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              and how to unite ſeveral Stones for the ſtrengthening of the Wall.
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              <s>A mong the Girders we reckon thoſe Cour­
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              ſes of large Stone which tie the out­
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              ward Shell to the Inward, and which bind the
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              Ribs one into the other, ſuch as are thoſe
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              which we ſaid in the laſt Chapter ought to be
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              made every five Foot. </s>
              <s>But there are other
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              Girders beſides, and thoſe principal ones,
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              which run the whole Length of the Wall to
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              embrace the Corners and ſtrengthen the whole
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              Work: But theſe latter are not ſo frequent,
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              and I do not remember ever to have ſeen
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              above two, or at moſt three in one Wall.
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              <s>Their Place is the Summit of the Wall, to be
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              as it were a Crown to the Whole, and to per­
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              form the ſame Service at the Top which the
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              other more frequent Girders at the Diſtance
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              of every five Foot do in the Middle, where
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              ſmaller Stones are allow'd; but in theſe other
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              Girders, which we call Cornices, as they are
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              fewer and of more Importance, ſo much the
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              larger and the ſtronger Stones they require. </s>
              <s>In
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              both according to their different Offices, the
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              beſt, the longeſt, and the thickeſt Stones are
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              neceſſary. </s>
              <s>The ſmaller Girders are made to
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              anſwer to the Rule and Plum-line with the
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              reſt of the Shell of the Wall: but theſe great
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              ones, like a Crown, project ſomewhat forwards.
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              <s>Theſe long, thick Stones muſt be laid exactly
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              plum, and be well link'd with the under
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              Courſes, ſo as to make a Kind of Pavement
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              at Top to ſhadow and protect the Subſtruc­
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              ture. </s>
              <s>The Way of placing theſe Stones one
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              upon the other, is to let the Middle of the
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              Stone above anſwer exactly to the Juncture of
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              the two in the Courſe below, ſo that its Weight
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              is equally pois'd upon them both; as (A.)
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              Which way of Working, as it ought not in­
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              deed to be neglected in any Part of the Wall,
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              ought to be particularly followed in the Gir­
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              ders. </s>
              <s>I have obſerved that the Ancients in
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              their checquer'd Works uſed to make their
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              Girders of five Courſes of Bricks, or at leaſt of
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              three, and that all of them, or at leaſt one
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              Courſe was of Stone, not thicker than the reſt,
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              but longer and broader; as (B.) But in their
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              ordinary Sort of Brick-work, I find they were
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              content for Girders to make at every five Foot
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              a Courſe of Bricks two Foot thick as (C)</s>
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              *</s>
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              <s>I KNOW ſome too have interſpers'd Plates or
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              Cramps of Lead of a conſiderable Length,
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              and as broad as the Wall was thick, in order
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              to bind the Work. </s>
              <s>But when they built with
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              very large Stone, I find they were contented
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              with fewer Girders, or even only with the
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              Cornices. </s>
              <s>In making the Cornices, which are
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              to girt in the Wall with the ſtrongeſt Liga­
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              ture, we ought to neglect none of the Rules
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              which we have laid down about the Girders;
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              namely, we ſhould uſe in them none but the
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              longeſt, thickeſt, and ſtrongeſt Stones, which
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              we ſhould put together in the moſt exact and
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              regular Order, each laid nicely even and level
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              by the Square and Plum-line. </s>
              <s>And we ought
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              to be more diligent and careful in this Part of
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              the Work, becauſe it is to gird in the Whole
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              Wall, which is more apt to ruinate in this Part
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              than in any other. </s>
              <s>The Covering too has its
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              Office with relation to the Wall; whence it
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              is laid down as a Rule, that to a Wall of crude
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              Bricks we are to make a Cornice of baked
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              ones, to the Intent that if any Water ſhould
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              chance to fall from the End of the Covering,
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              or from the Gutters, it may be it may do no
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              Miſchief, but that the Wall may be defended
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              by the Projecting of the Cornice. </s>
              <s>For which
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              Reaſon we ought to take Care that every Part
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              of the Wall have a Cornice over it for a
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              Covering to it, which ought to be firmly
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              wrought and well ſtucco'd over to repel all the
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              Injuries of the Weather. </s>
              <s>We are here again
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              to conſider in what Manner we are to unite
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              and conſolidate a Number of ſeperate Stones
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              into one Body of Wall; and the principal
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              Thing that offers itſelf to our Thoughts as
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              neceſſary, is good Lime; though I do not
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              take it to be the proper Cement for every Sort
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              of Stone: Marble, for Inſtance, if touch'd
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              with Lime, will not only looſe its Whiteneſs,
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              but will contract foul bloody Spots. </s>
              <s>But Mar­
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              ble, is ſo delicate and ſo coy of its Whiteneſs,
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              that it will hardly bear the Touch of any
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              Thing but itſelf; it diſdains Smoke; ſmear'd
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              </s>
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