Parker, John Henry: The archaeology of Rome (1,text): I. The primitive fortifications (Oxford [u.a.], 1874)

in.] Building-Materials. 3
VII. Later, or brick1. The walls of Babylon"1, and Persepolis,
and other ancient cities, were of brick, frequently sun-dried only,
and the only cement used in them was bitumen. The Roman
bricks are well burnt in kilns, and cemented with good lime-
mortar ; the earliest are made from the mud of the Tiber. They
are not found in Rome before the time of Camillus, and were
generally used as external brick linings to concrete walls to make
a smooth surface, which was sometimes to be afterwards faced with
marble slabs, or to be covered with bronze plates, as at the Pan-
theon of Agrippa. The most ancient bricks are flat, like tiles, mixed
with Pozzolana sand, very well made and very hard.
VIII. Material, or mortar, made with lime and sand. The sand
is of two kinds ; Fossicia, or river sand, and Pozzolana, (Pulvis
Puteolanus'). The quarries of this sand extend over the Campagna
on the eastern and southern side of Rome, and are often many
miles long, in corridors or roads always at the same level under-
ground, with many branches, and with sidings at intervals to enable
the carts to pass each other; the entrances to them are walled up
when they are abandoned. The best Pozzolana sand is always
rough; it crackles in the hand when rubbed, and leaves no stain
on a white dress, as Vitruvius mentions.
The Materia, or mortar, if well made, consists of three parts of
sand, and one of lime. The lime should always be quite fresh;
the mortar then becomes as hard and durable as natural concrete
stone. Pounded brick, or sometimes pounded stone, or the dust
of stone made in sawing it, is often used instead of Pozzolana sand,
in countries where the sand cannot readily be obtained. Whitewash
was made with river sand and broken pottery, and should be half
lime according to Vitruvius.
A particular kind of mortar or cement was used for the aque-
ducts in the time of the Empire, called in Latin, opus signinum, in
Italian, coccio pesto. This is made of broken brick or pottery with
good fresh lime, always used hot. This particular kind of cement
is in general a certain indication of an aqueduct, or of one of the
reservoirs or filtering-places belonging to them ; but it is sometimes
used for floors, also to keep out the moisture from the soil beneath,
as in the chambers of the Mamertine Prison, when it was partly
rebuilt in the time of the Emperor Tiberius.

1 See Vitruvius, lib. ii. c. 3, de
Lateribus.
“ Herodotus, Clio, i. 178.
" See Vitruvius, lib. ii. c. 9, de Ma-

teria ; also c. 4, de arena (or sand) ;
c. 5, de calce (or lime) • c. 6, de pul-
vere Puteolano.

B 2