with the two other ruins in the same neighbourhood, called
respectively _Kasr_ and _Birs-Nimroud_. Their bricks are held together by
an excellent mortar of lime, and cannot be separated without breaking.[177]
Elsewhere, at Mugheir for instance, the mortar is composed of lime and
ashes.[178]

[Illustration: PLATE I. BABYLON

FROM AN UNPUBLISHED DRAWING BY FELIX THOMAS.]

Finally, the soil of Mesopotamia furnished, and still furnishes, a kind of
natural mortar in the bituminous fountains that spring through the soil at
more than one point between Mossoul and Bagdad.[179] It is hardly ever used
in these days except in boatbuilding, for coating the planks and caulking.
In ancient times its employment was very general in the more carefully
constructed buildings, and, as it was found neither in Greece nor Syria, it
made a great impression upon travellers from those countries. They noted it
as one of the characteristics of Chaldaean civilization. In the Biblical
account of the Tower of Babel we are told: "They had brick for stone, and
slime had they for mortar."[180] Herodotus lays stress upon the same detail
in his description of the way in which the walls of Babylon were built: "As
they dug the ditches they converted the excavated earth into bricks, and
when they had enough, they burnt them in the kiln. Finally, for mortar they
used hot bitumen, and at every thirty courses of bricks they put a layer of
reeds interlaced."[181]

Those walls have long ago disappeared. For many centuries their ruins
afforded building materials for the inhabitants of the cities that have
succeeded each other upon and around the site of ancient Babylon, and now
their lines are only to be faintly traced in slight undulations of the
ground, which are here and there hardly distinguishable from the banks
that bordered the canals. But in those deserts of Lower Chaldaea, where the
nomad tent is now almost the only dwelling, structures have been found but
little damaged, in which layers of reeds placed at certain intervals among
the bricks may be easily distinguished. As a rule three or four layers are
strewn one upon the other, the rushes in one being at right angles to those
above and below it. Here and there the stalks may still be seen standing
out from the wall.[182] Fragments of bitumen are everywhere to be picked up
among the _debris_ about these buildings, upon which it must have been used
for mortar. It never seems to have been employed, howev