of bricks having a coating of coloured glaze or enamel, which
they largely used for wall decoration. The Chinese claim great antiquity
for their clay industries, but it is not improbable that the knowledge of
brickmaking travelled eastwards from Babylonia across the whole of Asia. It
is believed that the art of making glazed bricks, so highly developed
afterwards by the Chinese, found its way across Asia from the west, through
Persia and northern India, to China. The great wall of China was
constructed partly of brick, both burnt and unburnt; but this was built at
a comparatively late period (c. 210 B.C.), and there is nothing to show
that the Chinese had any knowledge of burnt bricks when the art flourished
in Babylonia.

Brickmaking formed the chief occupation of the Israelites during their
bondage in Egypt, but in this case the bricks were probably sun-dried only,
and not burnt. These bricks were made of a mixture of clay and chopped
straw or reeds, worked into a stiff paste with water. The clay was the
river mud from the banks of the Nile, and as this had not sufficient
cohesion in itself, the chopped straw (or reeds) was added as a binding
material. The addition of such substances increases the plasticity of wet
clay, especially if the mixture is allowed to stand for some days before
use; so that the action of the chopped straw was twofold; a fact possibly
known to the Egyptians. These sun-dried bricks, or "adobes," are still
made, as of old, on the banks of the Nile by the following method:--A
shallow pit or bed is prepared, into which are thrown the mud, chopped
straw and water in suitable proportions, and the whole mass is tramped on
until it is thoroughly mixed and of the proper consistence. This mixture is
removed in lumps and shaped into bricks, in moulds or by hand, the bricks
being simply sun-dried.

Pliny mentions that three kinds of bricks were made by the Greeks, but
there is no indication that they were used to any great extent, and
probably the walls of Athens on the side towards Mount Hymettus were the
most important brick-structures in ancient Greece. The Romans became
masters of the brickmaker's art, though they probably acquired much of
their knowledge in the East, during their occupation of Egypt and Greece.
In any case they revived and extended the manufacture of bricks about the
beginning of the Christian era; exercising great care in the selection and
preparation of their clay, and introducing