Alberti, Leone Battista, Architecture, 1755

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              <s>
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              the Ancients in their Publick Buildings always
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              eft a great many of both the afore-mention'd
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              Kinds of Apertures. </s>
              <s>This appears from their
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              Theatres, which if we obſerve are extremely
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              full of Apertures, not only Stair-caſes, but
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              Windows and Doors. </s>
              <s>And we ought ſo to
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              order the Proportions of theſe Openings, as
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              not to make very little ones in great Walls,
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              nor too large in ſmall ones. </s>
              <s>In theſe Sorts of
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              Apertures various Deſigns have been com­
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              mended; but the beſt Architects have never
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              made Uſe of any but Squares and ſtrait Lines.
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              </s>
              <s>However all have agreed in this, that let them
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              be of what Shape they will, they ſhould be ac­
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              modated to the Bigneſs and Form of the
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              Building. *The Doors, then they
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              fay ſhould always be more high than
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              broad; and the higheſt be ſuch as
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              are capable of receiving two Circles [A] one
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              upon t'other, and the loweſt ſhould be of
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              the Heighth of the Diagonal of a Square [B]
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              whereof the Groundſell is one of the Sides. </s>
              <s>It
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              is alſo convenient to place the Doors in ſuch a
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              Manner, that they may lead to as many Parts
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              of the Edifice as poſſible: And in order to give
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              Beauty to ſuch Apertures, Care muſt be taken
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              that thoſe of like Dimenſions correſpond with
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              each other both on the Right and Left. </s>
              <s>It was
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              uſual to leave the Windows and Doors in odd
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              Numbers, but ſo as for the Side ones to anſwer
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              each other, and that in the Middle to be
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              ſomewhat larger than the reſt. </s>
              <s>And particular
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              Regard was always had to the Strength of the
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              Building, for which Reaſon they contrived to
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              ſet the Openings clear from the Corners and
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              from the Columns, in the weakeſt Parts of the
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              Wall, but not ſo weak as to be inſufficient to
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              ſupport the Weight: It being their Cuſtom
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              to raiſe as many Parts of the Wall as they
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              could plum, and as it were of one Piece
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              without any Interruption from the Foundation
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              quite up to the Covering. </s>
              <s>There is a certain
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              Kind of an Aperture, which in Form and
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              Poſition imitates the Doors and Windows, but
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              which does not penetrate the whole Thickneſs
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              of the Wall, and ſo, as Niches leave very
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              handſome and convenient Seats for Statues and
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              Paintings. </s>
              <s>But in what Parts theſe are to be
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              left, as alſo how frequent and large, will be
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              ſhewn more diſtinctly when we come to treat
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              of the Ornaments of Edifices. </s>
              <s>We ſhall only
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              obſerve here, that they not only add to the
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              Beauty of the Work, but alſo ſave ſome Ex­
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              pence, as they make leſs Stone and Lime to
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              ſerve for the Walling. </s>
              <s>This chiefly is to be
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              taken Care of, that you make theſe Niches in
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              convenient Numbers, not too big, and of a juſt
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              Form; and ſo as in their Order to imitate the
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              Windows. </s>
              <s>And let them be as you will, I
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              have remark'd in the Structures of the Ancients,
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              that they never uſed to ſuffer them to take up
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              above the ſeventh Part of the Front, nor leſs
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              than the ninth. </s>
              <s>The Spaces between the
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              Columns are to be reckoned among the princi­
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              pal Apertures, and are to be leſt variouſly ac­
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              cording to the Variety of Buildings. </s>
              <s>But we
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              ſhall ſpeak of theſe more clearly in their
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              proper Place, and chieſly when we treat of
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              Sacred Edifies. </s>
              <s>Let it be ſufficient to premiſe
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              here, that thoſe Openings ſhould be left in ſuch
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              a Manner, as to have particular Reſpect to the
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              Nature of the Columns, which are deſign'd
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              for the Support of the Covering; and firſt, that
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              thoſe Columns be not too ſmall, nor ſtand too
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              thin, ſo as not to be duly able to bear the
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              Weight, nor too big, or ſet ſo thick as not to
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              leave open convenient Spaces for Paſſage.
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              </s>
              <s>Laſtly, the Apertures muſt be different, when
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              the Columns are frequent from what they are
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              when they ſtand thin, becauſe over frequent
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              Columns we lay an Architrave, and over the
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              others we turn an Arch. </s>
              <s>But in all Openings
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              over which we make Arches, we ſhould con­
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              trive to have the Arch never leſs than a half
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              Circle, with an Addition of the ſeventh Part
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              of half its Diameter: The moſt experienced
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              Workmen having found that Arch to be by
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              much the beſt adapted for enduring in a
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              Manner to Perpetuity; all other Arches being
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              thought leſs ſtrong for ſupporting the Weight,
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              and more liable to ruin. </s>
              <s>It is moreover imagi­
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              ned, that the half Circle is the only Arch
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              which has no Occaſion either for Chain or any
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              other Fortification; and all others, if you
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              don't either chain them or place ſome Weight
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              againſt them for a Counterpoiſe, are found by
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              their own Weight to burſt out and fall to ruin.
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              </s>
              <s>I will not omit here what I have taken Notice
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              of among the Ancients, a Contrivance certainly
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              very excellent and Praiſe-worthy: Their beſt
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              Architects placed theſe Apertures and the
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              Arches of the Roofs of their Temples in ſuch
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              a Manner, that even tho' you took away every
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              Column from under them, yet they would
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              ſtill ſtand firm and not fall down, the Arches
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              on which the Roof was placed being drawn
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              quite down to the Foundation with wonderful
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              Art, known but to few: So that the Work
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              upheld itſelf by being only ſet upon Arches; for
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              thoſe Arches having the ſolid Earth for their
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              Chain, no Wonder they ſtood firm without any
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              other Support.</s>
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