Alberti, Leone Battista, Architecture, 1755

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            <p type="main">
              <s>
                <pb xlink:href="003/01/153.jpg" pagenum="129"/>
              Iron ones. </s>
              <s>If Lead is daubed with any Sort
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              of Filch, it quickly ſpoils; and for this Reaſon
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              we ſhould take Care that our Roof be not a
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              convenient Harbour for Birds; or if it is a like­
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              ly Place for them to get together in, we ſhould
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              make our Stuff thick where their Dung is to
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              fall.
                <emph type="italics"/>
              Euſebius
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              tells us, that all round the Top
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              of
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              Solomon
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              's Temple there was a great Number
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              of Chains, to which hung four hundred little
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              Bells continually vibrating, the Noiſe of which
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              drove away the Birds. </s>
              <s>In the Covering we
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              alſo adorn the Ridge, Gutters and Angles, by
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              ſetting up Vaſes, Balls, Statues, Chariots and
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              the like, each of which we ſhall ſpeak of in
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              particular in its due Place. </s>
              <s>At preſent I do
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              not call to Mind any thing further relating to
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              this Sort of Ornaments in general, except that
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              each be adapted to the Place to which it is
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              moſt ſuitable.</s>
            </p>
            <p type="head">
              <s>CHAP. XII.</s>
            </p>
            <p type="main">
              <s>
                <emph type="italics"/>
              That the Ornaments of the Apertures are very pleaſing, but are attended with
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              many and various Difficulties and Inconveniences; that the falſe Apertures
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              are of two Sorts, and what is required in each.
                <emph.end type="italics"/>
              </s>
            </p>
            <p type="main">
              <s>The Ornaments of the Aperture give no
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              ſmall Beauty and Dignity to the Work,
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              but they are attended with many great Diffi­
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              culties, which cannot be provided againſt
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              without a good deal of Skill in the Artificer,
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              and a conſiderable Expence. </s>
              <s>They require very
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              large Stones, ſound, equal, handſome and rare,
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              which are Things not eaſily to be got, and
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              when got not eaſily removed, poliſhed, or ſet
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              up according to your Intention.
                <emph type="italics"/>
              Cicero
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              ſays,
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              that the Architects owned they could not ſet
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              up a Column exactly perpendicular, which in
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              all Apertures is abſolutely neceſſary both with
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              Reſpect to Duration and Beauty. </s>
              <s>There are
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              other Inconveniencies beſides; which, as far as
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              lies in our Power, we ſhall endeavour to pro­
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              vide againſt. </s>
              <s>An Aperture naturally implies
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              an Opening; but ſometimes behind this Open­
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              ing we run up a Wall which makes a Kind
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              of falſe Opening which is not pervious but
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              cloſed up; which for this Reaſon we ſhall ac­
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              cordingly call a falſe Aperture. </s>
              <s>This Sort of
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              Ornaments, as indeed were moſt of thoſe
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              which ſerve either to ſtrengthen the Work or
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              to ſave Expence, was firſt invented by the
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              Carpenters, and afterwards imitated by the
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              Maſons, who thereby gave no ſmall Beauty to
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              their Structures. </s>
              <s>Any of theſe Apertures would
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              be more beautiful if their Ribs were all of one
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              Piece, made of one entire Stone; and next to
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              this, is the having the Parts ſo nicely joined
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              that the Joints cannot be ſeen. </s>
              <s>The Ancients
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              uſed to erect their Columns and other Stones
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              which ſerved as Ribs to theſe falſe Apertures,
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              and fix them firm on their Baſes, before they
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              carried up the Wall; and herein they did very
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              wiſely; for by this Means they had more Room
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              to uſe their Engines, and could take the Per­
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              pendicular more exactly. </s>
              <s>You may plant your
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              Column perpendicular upon its Baſe in the fol­
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              lowing Manner: In the Baſe and at the Top
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              and Bottom of the Column mark the exact
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              Center of each Circle. </s>
              <s>Into the Center of the
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              Baſe faſten an iron Pin, ſoddering it in with
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              Lead, and make a Hole in the Center of the
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              Bottom of the Column, juſt big enough to re­
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              ceive the Pin which ſticks up in the Center of
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              the Baſe. </s>
              <s>In the Top of your Engine, or
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              Scaffolding, make a Mark exactly perpendicu­
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              lar over the Pin which ſticks up in the Center
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              of the Baſe, which you may find by letting ſall
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              Line from thence to that Pin. </s>
              <s>When you
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              have thus prepared every Thing, it will be no
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              hard Matter to move the Head of the Shaft
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              till its Center anſwers exactly to the Mark
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              which you have made above and is perpendi­
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              cular to the Center of its Baſe. </s>
              <s>I have obſerv­
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              ed from the Works of the Ancients that the
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              ſofter Sort of Marble may be ſmoothed with
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              the very ſame Inſtruments with which we
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              plane Wood. </s>
              <s>The Ancients alſo uſed to ſet
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              up their Stones quite rough, only ſmoothing
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              the Heads and Sides of them which were to
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              join to other Stones, and aſterwards when the
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              Building was raiſed, they poliſhed the Faces of
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              the Stones, which they had leſt rough before;
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              and this I believe they did that they might
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              leave the leaſt Expence that was poſſible to the
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              Hazards of their Engines: For it would have
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              been a much greater Loſs to them, if by Acci­
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              dent any Stone that was quite ſmoothed and
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              poliſhed had been let fall and broke, than if </s>
            </p>
          </chap>
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