1they are not deſigned to ſupport the Weight
of a vaulted Roof, but only a flat one of Sum
mers and Rafters. Let their Thickneſs there
fore be only one twentieth Part of their Height,
and let their Height be only once the Breadth
of the Front and an Half, and never more. At
the Angles of the Iſles come out Pilaſters from
the Naked of the Wall, running parallel with,
and on a Line with, the Columns, not leſs than
twice, nor more than three Times the Thick
neſs of the Wall. Others, ſtill more to ſtrength
en the Building, make ſuch a Pilaſter in the
Middle of the Row of Columns, in Breadth
three of the Diameters of one the Columns, or
at moſt four. The Columns themſelves too
muſt never have the ſame Solidity as thoſe
uſed in Temples; and therefore, if we make
our Colonades with an Architrave over it, we
may obſerve the following Rules. If the Co
lumns are to be Corinthian, ſubſtract a twelfth
Part from their Diameter; if Ionic, a tenth;
if Doric, a ninth. As for the Compoſition of
the other Members, the Capitals, Architrave,
Freze, Cornice, and the like, you may proceed
in the ſame Manner as in Temples.
of a vaulted Roof, but only a flat one of Sum
mers and Rafters. Let their Thickneſs there
fore be only one twentieth Part of their Height,
and let their Height be only once the Breadth
of the Front and an Half, and never more. At
the Angles of the Iſles come out Pilaſters from
the Naked of the Wall, running parallel with,
and on a Line with, the Columns, not leſs than
twice, nor more than three Times the Thick
neſs of the Wall. Others, ſtill more to ſtrength
en the Building, make ſuch a Pilaſter in the
Middle of the Row of Columns, in Breadth
three of the Diameters of one the Columns, or
at moſt four. The Columns themſelves too
muſt never have the ſame Solidity as thoſe
uſed in Temples; and therefore, if we make
our Colonades with an Architrave over it, we
may obſerve the following Rules. If the Co
lumns are to be Corinthian, ſubſtract a twelfth
Part from their Diameter; if Ionic, a tenth;
if Doric, a ninth. As for the Compoſition of
the other Members, the Capitals, Architrave,
Freze, Cornice, and the like, you may proceed
in the ſame Manner as in Temples.
*
†
⤡
CHAP. XV.
Of Colonades both with Architraves and with Arches; what Sort of Columns
are to be uſed in Baſiliques, and what Cornices, and where they are to be
placed; of the Height and Wedth of Windows and their Gratings; of the
Roofs and Doors of Baſiliques, and their Ornaments.
are to be uſed in Baſiliques, and what Cornices, and where they are to be
placed; of the Height and Wedth of Windows and their Gratings; of the
Roofs and Doors of Baſiliques, and their Ornaments.
Columns that are to have Arches over
them, ought by rights to be ſquare; for
if they were round, the Work would not be
true, becauſe the Heads of the Arches would
not lie plum upon the Solid of the Column
underneath; but as much as their Squares ex
ceeded a Circle, ſo much of them would hang
over the Void. To remedy this Defect, the
beſt ancient Maſters placed over the Capitals
of their Columns another Abacus or Plinth, in
Thickneſs ſometimes one fourth and ſometimes
one fiſth Part of the Diameter of the Column;
the upper Part of this Plinth, which went off
with a Cima-recta, was equal to the greateſt
Breadth of the Top of the Capital, and its Pro
jecture was equal to its Height, ſo that by this
means the Heads and Angles of the Arches had
a ſuller and firmer Seat. Colonades with
Arches, as well as thoſe with Architraves, are
various, ſome being thinner ſet, others cloſer,
and ſo on. In the cloſer Sort the Height of
the Void muſt be three Times and an half the
Breadth of the Aperture; in the thin Set, the
Height muſt be once the Breadth and two
thirds; in the leſs thin, the Height muſt be
twice the Breadth; in the cloſeſt of all, the
Breadth muſt be one third of the Height. We
have formerly obſerved, that an Arch is no
thing elſe but a Beam bent. We may there
fore give the ſame Ornaments to Arches as to
Architraves, according to the different Sorts of
Columns over which they are turned; beſides
which, if we would have our Structure very
rich, over the Heads of our Arches we may
run an Architrave, Freze, and Cornice in a
ſtraight Line, with the ſame Proportions as we
ſhould make them over Columns that ſhould
reach to that Height. But as the Baſilique is
ſometimes encompaſſed only with one ſingle
Iſle, and at other Times with two, the Place of
the Cornice over the Columns and Arches muſt
vary accordingly. In thoſe which are encom
paſſed only with one ſingle Portico, having di
vided the Height of your Wall into nine Parts,
the Cornice muſt go only to five; or if you
divide it into ſeven, to four. But in thoſe
which are to have double Iſles, the Cornice
muſt be placed at one third of the Height of
the Wall at leaſt, and at never more than three
eighths. We may alſo over the firſt Cornice,
as well for the greater Ornament as for real
Uſe, place other Columns, and eſpecially Pi
laſters, directly plum over the Centers of the
Columns which are below them. And this
indeed is of great Service, as it maintains the
Strength and Firmneſs of the Ribs of the Work,
and adds Majeſty to it, and at the ſame Time
takes off much from the Weight and Expence
of the Wall; and over this upper Colonade
too we make a regular Entablature, according
to the Order of the Columns. In Baſiliques
with double Side Iſles, we may raiſe three Rows
of Columns in this Manner one above another;
but in others we ſhould make but two. Where
them, ought by rights to be ſquare; for
if they were round, the Work would not be
true, becauſe the Heads of the Arches would
not lie plum upon the Solid of the Column
underneath; but as much as their Squares ex
ceeded a Circle, ſo much of them would hang
over the Void. To remedy this Defect, the
beſt ancient Maſters placed over the Capitals
of their Columns another Abacus or Plinth, in
Thickneſs ſometimes one fourth and ſometimes
one fiſth Part of the Diameter of the Column;
the upper Part of this Plinth, which went off
with a Cima-recta, was equal to the greateſt
Breadth of the Top of the Capital, and its Pro
jecture was equal to its Height, ſo that by this
means the Heads and Angles of the Arches had
a ſuller and firmer Seat. Colonades with
Arches, as well as thoſe with Architraves, are
various, ſome being thinner ſet, others cloſer,
and ſo on. In the cloſer Sort the Height of
the Void muſt be three Times and an half the
Breadth of the Aperture; in the thin Set, the
Height muſt be once the Breadth and two
thirds; in the leſs thin, the Height muſt be
twice the Breadth; in the cloſeſt of all, the
Breadth muſt be one third of the Height. We
have formerly obſerved, that an Arch is no
thing elſe but a Beam bent. We may there
fore give the ſame Ornaments to Arches as to
Architraves, according to the different Sorts of
Columns over which they are turned; beſides
which, if we would have our Structure very
rich, over the Heads of our Arches we may
run an Architrave, Freze, and Cornice in a
ſtraight Line, with the ſame Proportions as we
ſhould make them over Columns that ſhould
reach to that Height. But as the Baſilique is
ſometimes encompaſſed only with one ſingle
Iſle, and at other Times with two, the Place of
the Cornice over the Columns and Arches muſt
vary accordingly. In thoſe which are encom
paſſed only with one ſingle Portico, having di
vided the Height of your Wall into nine Parts,
the Cornice muſt go only to five; or if you
divide it into ſeven, to four. But in thoſe
which are to have double Iſles, the Cornice
muſt be placed at one third of the Height of
the Wall at leaſt, and at never more than three
eighths. We may alſo over the firſt Cornice,
as well for the greater Ornament as for real
Uſe, place other Columns, and eſpecially Pi
laſters, directly plum over the Centers of the
Columns which are below them. And this
indeed is of great Service, as it maintains the
Strength and Firmneſs of the Ribs of the Work,
and adds Majeſty to it, and at the ſame Time
takes off much from the Weight and Expence
of the Wall; and over this upper Colonade
too we make a regular Entablature, according
to the Order of the Columns. In Baſiliques
with double Side Iſles, we may raiſe three Rows
of Columns in this Manner one above another;
but in others we ſhould make but two. Where