Alberti, Leone Battista, Architecture, 1755

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1and Level. The Work will be more ſecure
ſtill, if between the Rubbiſh, and the Plaiſter
you lay a Row of plain Tiles cemented with
Mortar, mixed up with Oil.
As for Pave­
ments which are not to be expoſed to the open
Air. Varro directs us to make them in the
following Manner, which he tells us will be
very ſerviceable by means of its extraordinary
Dryneſs: Dig two Foot deep into the Ground,
then ram the Bottom ſoundly, and lay a Pave­
ment, either of Rubbiſh, or broken Brick,
leaving Vent-holes for the Vapours to diſcharge
themſelves; over this lay Coals well levell'd,
and ramm'd down, and over all a Cruſt made
of Sand, Mortar, and Aſhes.
Theſe Things
already mention'd, we have gathered from
Pliny and Vitruvius eſpecially: I will now ſet
down what I have with great Pains and Labour
diſcovered relating to Pavements from the
actual Works of the Ancients; from whence,
I conſeſs, I have learnt much more than from
their Writings.
We will begin with the Out­
ward Shell, which it is very difficult to make,
ſo as it ſhall not rot, or crack: For when once
it has been thoroughly ſoak'd with wet, and
comes to dry again, either by Sun, or Wind,
it dries by Scales, and as we ſee in Mud left
after Floods, the upper Coat ſhrinks, and
leaves Cracks which cannot be filled up; for
thoſe Parts which are dried and hardened,
cannot be made to cohere again by any Art
whatſoever, and thoſe which are ſtill moiſt,
yield and give Way to the leaſt Violence.
I
find the Ancients made their Shell either of
baked Earth, or of Stone; and where Mens
Feet were not to tread, they made their Tiles
ſometimes a Foot and a half every Way, ce­
mented with Mortar mixed up with Oil; we
alſo ſometimes meet with ſmall Bricks one
Inch in Thickneſs, two in Breadth, and four in
Length, join'd Sideways like a Fiſh's Back­
bone.
We often find Pavements of very large
Slabs of Marble, and others again of ſmaller
Pieces, and little Squares.
There are other An­
cient Pavements made all of one Piece, which
I ſuppoſe, was a Mixture of Lime, Sand, and
pounded Brick, of each a third Part: which
may be made more ſtrong and laſting yet, by
the Addition of one fourth Part of Tyber­
Stone, beat to Powder.
Others in this Sort of
Plaiſter mightily commend the Sand of Poz­
zuolo, which they call Rapillo. Plaiſter that is
deſigned for Pavements muſt be tried by con­
tinual beating, whereby it will daily acquire
greater Stiffneſs and Hardneſs, till it comes to be
in a Manner firmer than Stone itſelf. And it
is certain, that if this Plaiſter is ſprinkled with
Lime-water, and Linſeed-oil, it will grow
almoſt as hard as Glaſs, and deſy all Manner of
Weather.
Mortar worked up with Oil, is ſaid
in Pavements to keep out every Thing that is
noxious.
Under the Shell I obſerve they made
a Layer of Mortar, and ſmall Pieces of broken
Brick, of the Thickneſs of two or three Inches.
Next to this we find a Courſe of Rubbiſh, of
Bits of Bricks and Chippings of Stone, ſuch as
the Maſons cut off with their Chizzel, and this
is about a Foot in Thickneſs.
In ſome Places
betwixt theſe two Courſes, we find a regular
one of baked Tile, or Brick, and at the Bottom
of all a Layer of Stones, none bigger than a
Man's Fiſt.
The Stones found in Rivers,
which are called Male ones, as for Inſtance,
thoſe round ones which partake of the Nature
of Flint, or Glaſs, grow dry immediately when
they are taken out of the Water, whereas Brick
and ordinary Stone retain Moiſture a long
Time; for which Reaſon, many affirm that the
Damps which ariſe out of the Earth will never
be able to penetrate to the Shell of the Pave­
ment, if it is underlaid with thoſe Stones.
We
ſometimes find that they made little ſquare
Pilaſters a Foot and a half high next to the
Ground, ſtanding about two Foot diſtance one
from the other, upon which they laid baked
Tiles, and upon theſe the Pavement above­
mention'd.
But this Kind of Pavement belongs
chiefly to Baths; of which we ſhall treat in
their proper Place.
Pavements delight in
Damps, and a wet Air, while they are making,
and endure beſt and longeſt in moiſt and ſhady
Places; and their chief Enemies are the Looſe­
neſs of the Earth, and ſudden Droughts.
For
as repeated Rains make the Ground cloſe and
firm, ſo Pavements being heartily wetted, grow
compact, and hard as Iron.
That Part of the
Pavement which is to receive the Water falling
from the Gutters, ought to be made of the
largeſt and ſoundeſt Stones, ſuch as will not
eaſily be worn away by the continual Malice
(if we may ſo call it) of the Spouts that fall
upon them.
In ſuch Pavements as are laid
upon Timber-work, or Roofing, you muſt take
Care that the Ribs upon which it reſts are
ſufficiently ſtrong, and equal one to the other;
for if it ſhould be otherwife, or one Wall, or
Rafter which it lies upon, ſhould be ſtronger
than another, the Pavement would decay and
ſplit in that Part; for as Timber-work will
not always keep exactly in the ſame Condition,

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