1without Interruption; but only firſt to
ſtrengthen the Places you intend for the Seats
or Beds of your Columns, and then from one
to the other draw Arches with their Backs
downwards, ſo that the Plane or Level of the
Area will be the Chord of thoſe Arches; as
you may ſee by the Plate of the Page 41. let
B. For ſtanding thus, they will be leſs apt to
force their Way into the Earth in any one
Place, the Weight being counterpos'd and
thrown equally on both Sides on the Props of
the Arches. And how apt Columns are to
drive into the Ground, by means of the great
Preſſure of the Weight laid upon them, is
manifeſt from that Corner of the noble Tem
ple of Veſpaſian that ſtands to the North
Weſt. For being deſirous to leave the publick
Way, which was interrupted by that Angle, a
free and open Paſſage underneath, they broke
the Area of their Platform and turn'd an Arch
againſt the Wall, leaving that Corner as a Sort
of Plaiſter on the other Side of the Paſſage,
and fortifying it, as well as poſſible, with ſtout
Work, and with the Aſſiſtance of a Buttreſs.
Yet this at laſt, by the vaſt Weight of ſo great
a Building, and the giving Way of the Earth,
became ruinous. But let this ſuffice upon this
Head.
ſtrengthen the Places you intend for the Seats
or Beds of your Columns, and then from one
to the other draw Arches with their Backs
downwards, ſo that the Plane or Level of the
Area will be the Chord of thoſe Arches; as
you may ſee by the Plate of the Page 41. let
B. For ſtanding thus, they will be leſs apt to
force their Way into the Earth in any one
Place, the Weight being counterpos'd and
thrown equally on both Sides on the Props of
the Arches. And how apt Columns are to
drive into the Ground, by means of the great
Preſſure of the Weight laid upon them, is
manifeſt from that Corner of the noble Tem
ple of Veſpaſian that ſtands to the North
Weſt. For being deſirous to leave the publick
Way, which was interrupted by that Angle, a
free and open Paſſage underneath, they broke
the Area of their Platform and turn'd an Arch
againſt the Wall, leaving that Corner as a Sort
of Plaiſter on the other Side of the Paſſage,
and fortifying it, as well as poſſible, with ſtout
Work, and with the Aſſiſtance of a Buttreſs.
Yet this at laſt, by the vaſt Weight of ſo great
a Building, and the giving Way of the Earth,
became ruinous. But let this ſuffice upon this
Head.
*
CHAP. VI.
That there ought to be Vents left open in thick Walls from the Bottom to the
Top; the Difference between the Wall and the Foundation; the principal
Parts of the Wall; the three Methods of Walling; the Materials and
Form of the firſt Courſe or Layer.
Top; the Difference between the Wall and the Foundation; the principal
Parts of the Wall; the three Methods of Walling; the Materials and
Form of the firſt Courſe or Layer.
The Foundations being laid, we come
next to the Wall. But I will not omit
here a Precaution which belongs as well to the
Compleating of the Foundation as to the
Structure of the Wall. In large Buildings,
where the Wall is to be very thick, we ought
to leave Vents and Tunnels in the Body of the
Wall, at moderate Diſtances one from the other,
from the Foundation quite to the Top, through
which any Vapour or Damp that may happen
to engender or gather under Ground may have
free Paſſage without damaging the Work. The
Ancients in ſome of theſe Vents were uſed to
make winding Stairs, as well for the Sake of the
Beauty of the Contrivance itſelf, as for the
Convenience of paſſing up to the Top of the
Edifice, and perhaps too for the Saving of ſome
Expence. But to return to our Subject; be
tween the Foundation and the naked Wall there
is this Difference, that the former having the
Support of the Sides of the Trench, may be made
of nothing but Rubbiſh, whereas the Latter con
ſiſts of Variety of Parts, as we ſhall hereafter
ſhew. The principal Parts of the Wall are
theſe; firſt, the bottom Part, which begins
immediately from the Level of the Foundati
ons; this we call the firſt Courſe laid upon the
Level, or the Courſe riſing from the Ground:
The middle Parts, which girt and ſurround
the Wall, we ſhall call the ſecond Courſe: The
higheſt Parts, laſtly, that is to ſay, thoſe which
ſupport the top Roof, we call Cornices. Some
of the principal Parts or rather the prin
cipal Parts of all are the Corners of the
Wall, and the Pilaſters, or Columns, or any
thing elſe in their ſtead ſet in the Wall to ſup
port the Beams and Arches of the Covering;
all which are comprized under the Name of
Bones or Ribs. Likewiſe the Jambs on each
Side of all Openings partake of the Nature both
of Corners and of Columns. Moreover, the
Coverings of Openings, that is to ſay, the Lin
tels or Tranſoms, whether ſtrait or arched, are
alſo reckoned among the Bones. And indeed
I take an Arch to be nothing more than a Beam
bent, and the Beam or Tranſom to be only a
Column laid croſſways. Thoſe Parts which
interfere or lie between theſe principal Parts,
are very properly called Fillers up. There are
ſome Things throughout the whole Wall
which agree each with ſome one of the Parts
we have here ſpoken of; that is to ſay, the fill
ing up or cramming of the Middle of the Wall,
and the two Barks or Shells of each Side,
whereof that without is to bear the Sun and
Weather, and that within is to give Shade and
Shelter to the Inſide of the Platform. The
Rules for theſe Shells and for their ſtuffing are
various, according to the Variety of Structures.
The different Sorts of Structures are theſe; the
ordinary Sort, the chequer Sort and the Irregu
lar: And here it may not be amiſs to take
next to the Wall. But I will not omit
here a Precaution which belongs as well to the
Compleating of the Foundation as to the
Structure of the Wall. In large Buildings,
where the Wall is to be very thick, we ought
to leave Vents and Tunnels in the Body of the
Wall, at moderate Diſtances one from the other,
from the Foundation quite to the Top, through
which any Vapour or Damp that may happen
to engender or gather under Ground may have
free Paſſage without damaging the Work. The
Ancients in ſome of theſe Vents were uſed to
make winding Stairs, as well for the Sake of the
Beauty of the Contrivance itſelf, as for the
Convenience of paſſing up to the Top of the
Edifice, and perhaps too for the Saving of ſome
Expence. But to return to our Subject; be
tween the Foundation and the naked Wall there
is this Difference, that the former having the
Support of the Sides of the Trench, may be made
of nothing but Rubbiſh, whereas the Latter con
ſiſts of Variety of Parts, as we ſhall hereafter
ſhew. The principal Parts of the Wall are
theſe; firſt, the bottom Part, which begins
immediately from the Level of the Foundati
ons; this we call the firſt Courſe laid upon the
Level, or the Courſe riſing from the Ground:
The middle Parts, which girt and ſurround
the Wall, we ſhall call the ſecond Courſe: The
higheſt Parts, laſtly, that is to ſay, thoſe which
ſupport the top Roof, we call Cornices. Some
of the principal Parts or rather the prin
cipal Parts of all are the Corners of the
Wall, and the Pilaſters, or Columns, or any
thing elſe in their ſtead ſet in the Wall to ſup
port the Beams and Arches of the Covering;
all which are comprized under the Name of
Bones or Ribs. Likewiſe the Jambs on each
Side of all Openings partake of the Nature both
of Corners and of Columns. Moreover, the
Coverings of Openings, that is to ſay, the Lin
tels or Tranſoms, whether ſtrait or arched, are
alſo reckoned among the Bones. And indeed
I take an Arch to be nothing more than a Beam
bent, and the Beam or Tranſom to be only a
Column laid croſſways. Thoſe Parts which
interfere or lie between theſe principal Parts,
are very properly called Fillers up. There are
ſome Things throughout the whole Wall
which agree each with ſome one of the Parts
we have here ſpoken of; that is to ſay, the fill
ing up or cramming of the Middle of the Wall,
and the two Barks or Shells of each Side,
whereof that without is to bear the Sun and
Weather, and that within is to give Shade and
Shelter to the Inſide of the Platform. The
Rules for theſe Shells and for their ſtuffing are
various, according to the Variety of Structures.
The different Sorts of Structures are theſe; the
ordinary Sort, the chequer Sort and the Irregu
lar: And here it may not be amiſs to take