Alberti, Leone Battista, Architecture, 1755

Table of figures

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              the Sweep of the Fillet at Bottom; and in this
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              terminate all the Diameters that are in the
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              Thickneſs of the Shaſt, and it does not run
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              ſtrait like the Axis, but is compoſed of a great
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              Number of Lines, ſome ſtrait and ſome curve;
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              as we ſhall ſhew hereafter. </s>
              <s>The ſeveral Dia­
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              meters of Circles which we are to conſider in
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              different Parts of the Column, are ſive; the
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              Sweeps, the Diminutions, and the Swell or Belly
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              of the Shaft. </s>
              <s>The Sweeps are two, one at the
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              Top and the other at the Bottom of the Co­
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              lumn, and are called Sweeps upon account of
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              their running out a little beyond the Reſt of
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              the Shaft, The Diminutions are likewiſe two,
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              cloſe by the Sweeps at the Bottom and Top,
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              and are ſo called becauſe in thoſe Parts the
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              Shaft diminiſhes inwards. </s>
              <s>The Diameter of
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              the Swell or Belly of the Column is to be ob­
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              ſerved about the Middle of the Shaft, and is
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              called the Belly, becauſe the Column ſeems to
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              ſwell out juſt in that Part. </s>
              <s>Again, the Sweeps
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              differ from one another, for that which is at
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              the Bottom is formed by the Fillet and a ſmall
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              Curve running from the Fillet to the Body of
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              the Shaft; but the Sweep at the Top of the
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              Shaſt, beſides this Curve and its Fillet has like­
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              wiſe the Aſtragal. </s>
              <s>Laſtly, the Out-lines muſt
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              be formed in the following Manner: On the
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              Pavement, or upon the flat Side of a Wall,
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              which is proper for the Drawing your Deſign,
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              draw a ſtrait Line, of the Length which you
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              intend to give the Column, which perhaps is
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              as yet in the Quarry. </s>
              <s>This Line we call the
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              Axis of the Shaft. </s>
              <s>Then divide this Axis into
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              a certain Number of determinate Parts, ac­
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              cording to the Nature of the Building, and of
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              the various Sorts of Columns which you are to
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              erect, of which Variety we ſhall ſpeak in due
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              Time; and according to a due Proportion of
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              theſe Parts you muſt make the Diameter of the
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              Bottom of your Shaft, with a little Line drawn
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              acroſs the Axis. </s>
              <s>The Diameter you divide in­
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              to four-and-twenty Parts, one of which you
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              give to the Height of the Fillet, which Height
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              we mark upon the Wall with a ſmall Stroke;
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              then take three more of thoſe Parts, and at
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              that Height make a Mark in the Axis of the
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              Shaft, which is to be the Center of the next
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              Diminution, and through this Center draw a
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              Line exactly parallel with the Diameter of the
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              Bottom of the Shaft, which Line muſt be the
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              Diameter of the lower Diminution, and be one
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              ſeventh Part ſhorter than the Diameter of the
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              Bottom of the Shaft. </s>
              <s>Having marked theſe
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              two Lines, that is to ſay, the Diameter of the
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              Diminution, and the Fillet, draw from the
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              Point of the End of the Fillet to the Point of
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              that Diameter in the Shaft of the Column a
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              curve Line, as eaſy and neat as poſſible; the
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              Beginning of this curve Line muſt be one Quar­
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              ter of a little Circle, the Semi-diameter of
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              which muſt be the Height of the Fillet. </s>
              <s>Then
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              divide the whole Length of the Shaft into ſeven
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              equal Parts, and mark thoſe Diviſions with lit­
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              tle Dots. </s>
              <s>At the fourth Dot, counting from
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              the Bottom, make the Center of the Belly of
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              the Shaft, acroſs which draw its Diameter,
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              whoſe Length muſt be equal to the Diameter
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              of the Diminution at the Bottom. </s>
              <s>The Di­
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              minution and Sweep at the Top muſt be made
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              as follows: According to the Species of the
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              Column, of which we ſhall treat elſewhere,
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              take the Diameter of the upper Superficies from
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              the Diameter of the Bottom of the Shaft, and
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              draw it at the Top of the Column in your De­
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              ſign; which Diameter ſo drawn muſt be di­
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              vided into twelve Parts, one of which Parts
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              muſt be allowed to the Projecture of the Fillet
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              and Aſtragal, giving two thirds of it to the
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              latter, and one third to the former. </s>
              <s>Then
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              make the Center of your Diminution, at the
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              Diſtance of one and a half of thoſe Parts from
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              the Center of the upper Surface of the Shaft,
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              and the Diameter of this Diminution a ninth
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              Part leſs than the largeſt Diameter of that Sur­
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              face. </s>
              <s>You muſt afterwards draw the Curve or
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              Sweep in the ſame Manner as I taught you to
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              draw that below. </s>
              <s>Laſtly, having thus marked
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              in your Deſign the Sweeps, Diminutions, and
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              all the other Particulars which we have here
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              mentioned, draw a ſtrait Line from the Dimi­
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              nution at the Top, and another from the Di­
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              minution at the Bottom to the Diameter of the
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              Belly or Swell of the Column, and this will
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              make in your Deſign what we called the Out­
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              line of the Column, and by this Line you may
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              make a Model of Wood by which your Ma­
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              ſons may ſhape and finiſh the Column itſelf.
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              </s>
              <s>The Superficies of the Bottom of the Shaft, if
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              the Column be exactly rounded, muſt make
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              equal Angles on all Sides with the Axis in the
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              Middle, and with the like Superficies at the Top
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              of the Shaft. </s>
              <s>Theſe Things I do not find com­
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              mitted to writing by any of the Ancients, but I
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              have gathered them by my own Induſtry and
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              Application from the Works of the beſt Ma­
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              ſters. </s>
              <s>All that is to follow may be for the
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              moſt Part referred to the Proportions of the
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              Lines already treated of, and will be very de­
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              lightful and of great Uſe, eſpecially to the Im­
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              provement of Painters.</s>
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              *</s>
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              The End of Book
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