Water towers stand at the sides of the streets, small pillars of masonry preserved ordinarily to the height of 20 feet. Usually on one side there is a deep perpendicular groove (shown in [Fig. 103]) in which ran the pipe that carried the water to the top of the tower, where it was received by a small open reservoir, presumably of metal, and distributed through numerous small pipes leading to the fountains and to private houses. The sides of the towers are often covered with incrustations of lime deposited from the water, in which the impressions of the lead pipes are still to be seen; in the case of one tower, at the northeast corner of Insula VI. xiii, a number of the pipes have been preserved. A reservoir was placed also on the top of the commemorative arch at the lower end of Mercury Street, on which stood the bronze statue of Nero or Caligula ([p. 48]); the traces of the pipes leading from it are clearly seen on the surface of the arch. Similar water towers are in use now in Constantinople and Palermo, having been introduced into the latter city, it would seem, by the Saracens, who very likely took their water system from that of the Turkish capital.

Fig. 103.—Fountain, water tower, and street shrine, corner of Stabian and Nola streets.

In consequence of these arrangements, Pompeii was well supplied with water. There were flowing jets in all houses except the poorest, and in some the amount used must have been large. In the house of the Vettii there were no less than sixteen jets, in the house of the Silver Wedding, seven; and an equally generous distribution is found in many other of the more extensive private establishments. Large quantities of water were used also in the public baths. The water pipes were made of sheet lead folded together, a transverse section showing the shape of a pear. They were of all sizes, according to the pressure; the flow of water was regulated by means of stopcocks, much like those in use to-day.

Across the street from the Baths near the Forum, on the west, is a deep reservoir, of which we give the plan ([Fig. 104]). It is built partly below the level of the sidewalk, and measures about 50 feet in length and 13 in width, being covered by a vault. In the south end is a window (c), reached from one of the stairways; when the reservoir was filled to the bottom of the window, it contained not far from ninety-five thousand gallons. There were two outlets. One was at the level of the floor, closed by means of a bronze slide; the grooves in which the slide worked are preserved. This must have been used only when the reservoir was cleaned. The other outlet was placed about three feet above the floor, so that the water could be drawn off without disturbing the bottom. On the flat roof were rooms the arrangement of which cannot be determined.

Similar reservoirs are found in Constantinople, designed to furnish a supply of water in case of siege. Such may have been the purpose of our structure, which seems to have been built in the early years of the Roman colony. The residents, remembering the hardships of the siege of Sulla, may have thought it necessary to make provision against a similar strait in the future.

Fig. 104.—Plan of reservoir, west of the Baths near the Forum.
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