by two other streams, and conveyed by a channel of stone
to the Crooked Aqueduct. From this they are conveyed to another which is
the Long Aqueduct; and then, with various accessions, into a third,
termed the Aqueduct of Justinian. From this they enter a vaulted
conduit, which skirts the hills on the left side of the valley, and
crosses a broad valley 2 m. below the Aqueduct of Justinian, by means of
an aqueduct, with two tiers of arches of a very beautiful construction.
The conduit then proceeds onward in a circuitous route, till it reaches
the reservoir of Egri Kapu, situated just without and on the walls of
the city. From this the water is conducted to the various quarters of
the city, and also to the reservoir of St Sophia, which supplies the
seraglio of the grand signior. The Long Aqueduct (Usun Kemer) is more
imposing by its extent than the Crooked one, but is far inferior in the
regularity of design and disposition of the materials. It is evidently a
work of the Turks. It consists of two tiers of arches, the lower being
forty-eight in number, and the upper fifty. The whole length was about
2200 ft., and the height 80 ft. The aqueduct of Justinian (Muallak Kemer
or "Hanging Aqueduct") is without doubt one of the finest monuments
which remain to us of the middle ages. It consists of two tiers of large
pointed arches, pierced transversely. Those of the lower story have 55
ft. of span, the upper ones 40 ft. The piers are supported by strong
buttresses, and at different heights they have little arches passing
through them laterally, which relieve the deadness of the solid pillar.
The length of this aqueduct is 720 ft. and the height 108 ft. This
aqueduct has been attributed both to Constantine I. and to Justinian,
the latter being perhaps the more probable.

Besides the waters of Belgrad, Constantinople was supplied from several
other principal sources, one of which took its rise on the heights of
the same mountains, 3 or 4 m. east of Belgrad. This was conveyed in a
similar manner by an arched channel elevated, when it was necessary, on
aqueduct bridges, till it reached the northern parts of the city. It was
in the course of this aqueduct that the contrivance of the _souterasi_
or hydraulic obelisks, described by Andreossy (on his voyage to the
Black Sea, the account of the Thracian Bosporus), was constructed, which
excited some attention, as being an improvement on the method of
conducting water by aqueduct bridges.