1Beams ought alſo to be related to one another;
that is, they ſhould be of the ſame Kind of
Timber, and raiſed in the ſame Wood, ex
poſed if poſſible to the ſame Winds, and fell'd
the ſame Day; that being endued with the
ſame natural Strength, they may bear their
Shares equally in the Service. Let the Beds for
the Beams be exactly level, and perfectly firm
and ſtrong; and in laying them take care
that the Timber does not touch any Lime,
and let it have clear and open Vents all about
it, that it may not be tainted by the Contact
of any other Materials, nor decay by being
too cloſe ſhut up. For a Bed for the Beams,
ſpread under them either Fern, a very dry
Kind of Herb, or Aſhes, or rather Lees of
Oil with the bruiſed Olives. But if your Tim
ber is ſo ſhort, that you cannot make a Beam
of one Piece, you muſt join two or more to
gether, in ſuch a Manner as to give them the
Strength of an Arch; that is to ſay, ſo that
the upper Line of the compacted Beam, can
not poſſibly by any Preſſure become ſhorter;
and on the contrary, that the lower Line can
not grow longer: And there muſt be a Sort
of Cord to bind the two Beams together,
which ſhove one another with their Heads,
with a ſtrong Ligature. The Rafters, and all
the reſt of the Wood-work, depend upon the
Goodneſs and Soundneſs of the Beams; being
nothing elſe but Beams ſplit. Boards or Planks
are thought to be inconvenient if too thick, be
cauſe whenever they begin to warp they throw
out the Nails; and thin Boards, eſpecially in
Coverings expoſed to the Air, they ſay, muſt
be faſtened with Nails in Pairs, ſo as to ſe
cure the Corners, the Sides and the Middle.
They tell us, that ſuch Nails as are to bear any
tranſverſe Weight, muſt be made thick; but as
for others, it matters not if they are thinner;
but then they muſt be longer, and have
broader Heads.
that is, they ſhould be of the ſame Kind of
Timber, and raiſed in the ſame Wood, ex
poſed if poſſible to the ſame Winds, and fell'd
the ſame Day; that being endued with the
ſame natural Strength, they may bear their
Shares equally in the Service. Let the Beds for
the Beams be exactly level, and perfectly firm
and ſtrong; and in laying them take care
that the Timber does not touch any Lime,
and let it have clear and open Vents all about
it, that it may not be tainted by the Contact
of any other Materials, nor decay by being
too cloſe ſhut up. For a Bed for the Beams,
ſpread under them either Fern, a very dry
Kind of Herb, or Aſhes, or rather Lees of
Oil with the bruiſed Olives. But if your Tim
ber is ſo ſhort, that you cannot make a Beam
of one Piece, you muſt join two or more to
gether, in ſuch a Manner as to give them the
Strength of an Arch; that is to ſay, ſo that
the upper Line of the compacted Beam, can
not poſſibly by any Preſſure become ſhorter;
and on the contrary, that the lower Line can
not grow longer: And there muſt be a Sort
of Cord to bind the two Beams together,
which ſhove one another with their Heads,
with a ſtrong Ligature. The Rafters, and all
the reſt of the Wood-work, depend upon the
Goodneſs and Soundneſs of the Beams; being
nothing elſe but Beams ſplit. Boards or Planks
are thought to be inconvenient if too thick, be
cauſe whenever they begin to warp they throw
out the Nails; and thin Boards, eſpecially in
Coverings expoſed to the Air, they ſay, muſt
be faſtened with Nails in Pairs, ſo as to ſe
cure the Corners, the Sides and the Middle.
They tell us, that ſuch Nails as are to bear any
tranſverſe Weight, muſt be made thick; but as
for others, it matters not if they are thinner;
but then they muſt be longer, and have
broader Heads.
*
BRASS Nails are moſt durable in the Air, or
in wet; but I have found the Iron ones to be
ſtronger under Cover. For fattening of the
Rafters together, wooden Pins are much uſed.
Whatever we have here ſaid of Coverings of
Wood, muſt be obſerved alſo with relation to
thoſe of Stone; for ſuch Stones as have Veins,
or Faults running croſſways, muſt be rejected
for the making of Beams, and uſed in Columns;
or if there are any ſmall inconſiderable Faults,
the Side of the Stone in which it appears,
when it is uſed, muſt be laid downwards,
Veins running longways in Beams of any Sort,
are more excuſable than tranſverſe ones.
Tables, or Scantlings of Stones alſo, as well
for other Reaſons, as upon Account of their
Weight, muſt not be made too thick. Laſtly,
the Beams, Rafters, and Planks that are uſed
in Coverings, whether of Wood, or Stone,
muſt be neither ſo thin, nor ſo few as not to
be ſufficient for upholding themſelves, and their
Burthens; nor ſo thick, or ſo crouded as to
take from the Beauty, and Symmetry of the
Work; but thoſe are things we ſhall ſpeak of
elſewhere. And thus much for Coverings of
ſtraight Lines; unleſs it may be proper to men
tion one Thing which is in my Opinion tobe neg
lected in no Sort of Structure. The Philoſophers
have obſerved, that Nature in forming the Bo
dies of Animals, always takes care to finiſh her
Work in ſuch a Manner, that the Bones ſhould
all communicate, and never be ſeperate one
from the other: So we alſo ſhould connect the
Ribs togther, and faſten them together well
with Nerves and Ligatures; ſo that the Com
munication among the Ribs ſhould be ſo con
tinued, that if all the reſt of the Structure
failed, the Frame of the Work ſhould yet
ſtand firm and ſtrong with all its Parts and
Members.
in wet; but I have found the Iron ones to be
ſtronger under Cover. For fattening of the
Rafters together, wooden Pins are much uſed.
Whatever we have here ſaid of Coverings of
Wood, muſt be obſerved alſo with relation to
thoſe of Stone; for ſuch Stones as have Veins,
or Faults running croſſways, muſt be rejected
for the making of Beams, and uſed in Columns;
or if there are any ſmall inconſiderable Faults,
the Side of the Stone in which it appears,
when it is uſed, muſt be laid downwards,
Veins running longways in Beams of any Sort,
are more excuſable than tranſverſe ones.
Tables, or Scantlings of Stones alſo, as well
for other Reaſons, as upon Account of their
Weight, muſt not be made too thick. Laſtly,
the Beams, Rafters, and Planks that are uſed
in Coverings, whether of Wood, or Stone,
muſt be neither ſo thin, nor ſo few as not to
be ſufficient for upholding themſelves, and their
Burthens; nor ſo thick, or ſo crouded as to
take from the Beauty, and Symmetry of the
Work; but thoſe are things we ſhall ſpeak of
elſewhere. And thus much for Coverings of
ſtraight Lines; unleſs it may be proper to men
tion one Thing which is in my Opinion tobe neg
lected in no Sort of Structure. The Philoſophers
have obſerved, that Nature in forming the Bo
dies of Animals, always takes care to finiſh her
Work in ſuch a Manner, that the Bones ſhould
all communicate, and never be ſeperate one
from the other: So we alſo ſhould connect the
Ribs togther, and faſten them together well
with Nerves and Ligatures; ſo that the Com
munication among the Ribs ſhould be ſo con
tinued, that if all the reſt of the Structure
failed, the Frame of the Work ſhould yet
ſtand firm and ſtrong with all its Parts and
Members.
CHAP. XIII.
Of Coverings, or Roofs of Curve Lines; of Arches, their Difference and Con
ſtruction, and how to ſet the Stones in an Arch.
ſtruction, and how to ſet the Stones in an Arch.
We come now to ſpeak of Roofs made
of Curve Lines, and we are firſt to
conſider thoſe Particulars wherein they exactly
agree with Coverings of ſtrait Lines. A curvili
near Roof is compoſed of Arches; and we have
already ſaid that an Arch is nothing but a
Beam bent. We might alſo here mention the
Ligatures, and thoſe Things which muſt be
uſed for filling up the Vacuities; but I would
be underſtood more clearly, by explaining
what I take to be the Nature of an Arch, and
of what Parts it conſiſts.
of Curve Lines, and we are firſt to
conſider thoſe Particulars wherein they exactly
agree with Coverings of ſtrait Lines. A curvili
near Roof is compoſed of Arches; and we have
already ſaid that an Arch is nothing but a
Beam bent. We might alſo here mention the
Ligatures, and thoſe Things which muſt be
uſed for filling up the Vacuities; but I would
be underſtood more clearly, by explaining
what I take to be the Nature of an Arch, and
of what Parts it conſiſts.