CHAP. IX.
Of the Girders of Stone, of the Ligament and Fortification of the Cornices,
and how to unite ſeveral Stones for the ſtrengthening of the Wall.
and how to unite ſeveral Stones for the ſtrengthening of the Wall.
A mong the Girders we reckon thoſe Cour
ſes of large Stone which tie the out
ward Shell to the Inward, and which bind the
Ribs one into the other, ſuch as are thoſe
which we ſaid in the laſt Chapter ought to be
made every five Foot. But there are other
Girders beſides, and thoſe principal ones,
which run the whole Length of the Wall to
embrace the Corners and ſtrengthen the whole
Work: But theſe latter are not ſo frequent,
and I do not remember ever to have ſeen
above two, or at moſt three in one Wall.
Their Place is the Summit of the Wall, to be
as it were a Crown to the Whole, and to per
form the ſame Service at the Top which the
other more frequent Girders at the Diſtance
of every five Foot do in the Middle, where
ſmaller Stones are allow'd; but in theſe other
Girders, which we call Cornices, as they are
fewer and of more Importance, ſo much the
larger and the ſtronger Stones they require. In
both according to their different Offices, the
beſt, the longeſt, and the thickeſt Stones are
neceſſary. The ſmaller Girders are made to
anſwer to the Rule and Plum-line with the
reſt of the Shell of the Wall: but theſe great
ones, like a Crown, project ſomewhat forwards.
Theſe long, thick Stones muſt be laid exactly
plum, and be well link'd with the under
Courſes, ſo as to make a Kind of Pavement
at Top to ſhadow and protect the Subſtruc
ture. The Way of placing theſe Stones one
upon the other, is to let the Middle of the
Stone above anſwer exactly to the Juncture of
the two in the Courſe below, ſo that its Weight
is equally pois'd upon them both; as (A.)
Which way of Working, as it ought not in
deed to be neglected in any Part of the Wall,
ought to be particularly followed in the Gir
ders. I have obſerved that the Ancients in
their checquer'd Works uſed to make their
Girders of five Courſes of Bricks, or at leaſt of
three, and that all of them, or at leaſt one
Courſe was of Stone, not thicker than the reſt,
but longer and broader; as (B.) But in their
ordinary Sort of Brick-work, I find they were
content for Girders to make at every five Foot
a Courſe of Bricks two Foot thick as (C)
ſes of large Stone which tie the out
ward Shell to the Inward, and which bind the
Ribs one into the other, ſuch as are thoſe
which we ſaid in the laſt Chapter ought to be
made every five Foot. But there are other
Girders beſides, and thoſe principal ones,
which run the whole Length of the Wall to
embrace the Corners and ſtrengthen the whole
Work: But theſe latter are not ſo frequent,
and I do not remember ever to have ſeen
above two, or at moſt three in one Wall.
Their Place is the Summit of the Wall, to be
as it were a Crown to the Whole, and to per
form the ſame Service at the Top which the
other more frequent Girders at the Diſtance
of every five Foot do in the Middle, where
ſmaller Stones are allow'd; but in theſe other
Girders, which we call Cornices, as they are
fewer and of more Importance, ſo much the
larger and the ſtronger Stones they require. In
both according to their different Offices, the
beſt, the longeſt, and the thickeſt Stones are
neceſſary. The ſmaller Girders are made to
anſwer to the Rule and Plum-line with the
reſt of the Shell of the Wall: but theſe great
ones, like a Crown, project ſomewhat forwards.
Theſe long, thick Stones muſt be laid exactly
plum, and be well link'd with the under
Courſes, ſo as to make a Kind of Pavement
at Top to ſhadow and protect the Subſtruc
ture. The Way of placing theſe Stones one
upon the other, is to let the Middle of the
Stone above anſwer exactly to the Juncture of
the two in the Courſe below, ſo that its Weight
is equally pois'd upon them both; as (A.)
Which way of Working, as it ought not in
deed to be neglected in any Part of the Wall,
ought to be particularly followed in the Gir
ders. I have obſerved that the Ancients in
their checquer'd Works uſed to make their
Girders of five Courſes of Bricks, or at leaſt of
three, and that all of them, or at leaſt one
Courſe was of Stone, not thicker than the reſt,
but longer and broader; as (B.) But in their
ordinary Sort of Brick-work, I find they were
content for Girders to make at every five Foot
a Courſe of Bricks two Foot thick as (C)
*
I KNOW ſome too have interſpers'd Plates or
Cramps of Lead of a conſiderable Length,
and as broad as the Wall was thick, in order
to bind the Work. But when they built with
very large Stone, I find they were contented
with fewer Girders, or even only with the
Cornices. In making the Cornices, which are
to girt in the Wall with the ſtrongeſt Liga
ture, we ought to neglect none of the Rules
which we have laid down about the Girders;
namely, we ſhould uſe in them none but the
longeſt, thickeſt, and ſtrongeſt Stones, which
we ſhould put together in the moſt exact and
regular Order, each laid nicely even and level
by the Square and Plum-line. And we ought
to be more diligent and careful in this Part of
the Work, becauſe it is to gird in the Whole
Wall, which is more apt to ruinate in this Part
than in any other. The Covering too has its
Office with relation to the Wall; whence it
is laid down as a Rule, that to a Wall of crude
Bricks we are to make a Cornice of baked
ones, to the Intent that if any Water ſhould
chance to fall from the End of the Covering,
or from the Gutters, it may be it may do no
Miſchief, but that the Wall may be defended
by the Projecting of the Cornice. For which
Reaſon we ought to take Care that every Part
of the Wall have a Cornice over it for a
Covering to it, which ought to be firmly
wrought and well ſtucco'd over to repel all the
Injuries of the Weather. We are here again
to conſider in what Manner we are to unite
and conſolidate a Number of ſeperate Stones
into one Body of Wall; and the principal
Thing that offers itſelf to our Thoughts as
neceſſary, is good Lime; though I do not
take it to be the proper Cement for every Sort
of Stone: Marble, for Inſtance, if touch'd
with Lime, will not only looſe its Whiteneſs,
but will contract foul bloody Spots. But Mar
ble, is ſo delicate and ſo coy of its Whiteneſs,
that it will hardly bear the Touch of any
Thing but itſelf; it diſdains Smoke; ſmear'd
Cramps of Lead of a conſiderable Length,
and as broad as the Wall was thick, in order
to bind the Work. But when they built with
very large Stone, I find they were contented
with fewer Girders, or even only with the
Cornices. In making the Cornices, which are
to girt in the Wall with the ſtrongeſt Liga
ture, we ought to neglect none of the Rules
which we have laid down about the Girders;
namely, we ſhould uſe in them none but the
longeſt, thickeſt, and ſtrongeſt Stones, which
we ſhould put together in the moſt exact and
regular Order, each laid nicely even and level
by the Square and Plum-line. And we ought
to be more diligent and careful in this Part of
the Work, becauſe it is to gird in the Whole
Wall, which is more apt to ruinate in this Part
than in any other. The Covering too has its
Office with relation to the Wall; whence it
is laid down as a Rule, that to a Wall of crude
Bricks we are to make a Cornice of baked
ones, to the Intent that if any Water ſhould
chance to fall from the End of the Covering,
or from the Gutters, it may be it may do no
Miſchief, but that the Wall may be defended
by the Projecting of the Cornice. For which
Reaſon we ought to take Care that every Part
of the Wall have a Cornice over it for a
Covering to it, which ought to be firmly
wrought and well ſtucco'd over to repel all the
Injuries of the Weather. We are here again
to conſider in what Manner we are to unite
and conſolidate a Number of ſeperate Stones
into one Body of Wall; and the principal
Thing that offers itſelf to our Thoughts as
neceſſary, is good Lime; though I do not
take it to be the proper Cement for every Sort
of Stone: Marble, for Inſtance, if touch'd
with Lime, will not only looſe its Whiteneſs,
but will contract foul bloody Spots. But Mar
ble, is ſo delicate and ſo coy of its Whiteneſs,
that it will hardly bear the Touch of any
Thing but itſelf; it diſdains Smoke; ſmear'd