It is proper I should say in what manner the earth removed from the trench was disposed of, and how the wall was constructed. The earth, as fast as it was removed from the trench, was converted into bricks and baked in furnaces: when thus prepared, melted bitumen was used instead of mortar; and between every thirtieth course of bricks there was inserted a layer of reeds. The sides of the trench were first lined with brickwork, and then the wall raised in the manner described. On the upper edges of the wall, and opposite to one another, were constructed turrets; between these turrets a space was left wide enough for a chariot and four horses to pass and turn. In the walls were one hundred gates, all of brass, with posts and upper lintels of the same. Eight days' journey from Babylon is a city named Is, near which runs a small river of the same name, discharging itself into the Euphrates; this river brings down with its waters clots of bitumen in large quantities. From this source was derived the bitumen used in cementing the walls of Babylon. Such are the fortifications of Babylon. The city is divided into two portions by the river Euphrates, which runs through the midst of it. This river rises in Armenia, and throughout its course is wide, deep, and swift; it empties itself into the Red sea.[7] Each of the city walls is extended to the river, where it makes an angle, and, with a coating of burnt bricks, lines the sides of the river. The city is filled with houses of three or four stories, forming streets in straight lines, and running parallel with one another, the cross streets opening upon the river through as many smaller brazen gates, placed in the breastwork of the river walls. Within the principal wall just mentioned is a second, not much inferior to the first in strength, tho less in width.