The drains of the early Babylonians were either made of bricks, or else of baked clay rings. Of the larger type of drain or water conduit generally used to drain the upper stages of ziggurats, we have a good example in Pl. XI. Similar drains were discovered by Loftus at Erech, though he mistook them for supporting buttresses,[72] to which they bear a striking resemblance. In the temple court at Nippur numerous drains of the second class were discovered. These were constructed of terra-cotta rings set one on the top of the other, and sometimes provided with a bell-shaped top, while occasionally it was surmounted by a terra-cotta floor,[73] as in Fig. 10. The average diameter of the rings composing this drain was two feet and three-quarters, and it descended some six and a half feet. At Bismâya a drain consisting of round tiles about eight inches in diameter was discovered, while similar drains made of terra-cotta rings superimposed one on the top of the other were discovered by Taylor at Muḳeyyer (Ur). Frequently these shafts were double as in the illustration (Fig. 11). The rings composing this drain were two feet in diameter and about a foot and a half broad, and in some instances they were cemented together by means of a thin layer of bitumen. “For about a foot right round these drain-pipes and throughout their whole length, were pieces of broken pottery, the more effectually to drain the mound.”[74] Over the mouth of the top ring, which is of a different shape to the others, were layers of perforated bricks leading up to the top of the mound. Sometimes these drains consist of as many as forty of these rings. Numerous drains made of both bricks and tiles were discovered at Bismâya, while the drainage system at Fâra and other early Babylonian sites seems to have been very extensive. The main drains in Babylonia and Assyria frequently assumed the form of vaulted aqueducts. Concerning the drainage of the inner rooms, the palace of Sargon at Khorsabad is our best source of information. Nearly all of the rooms were drained by a hole cut in a stone in the centre of the floor towards which the brick floor gradually sloped; the water passed through the hole into a circular brick conduit, which descended into a horizontal drain connected with the main vaulted drain to which reference will be made later on (cf. p. 174).