The distribution of the water along its course, as well as throughout the city, was regulated with scrupulous care. Besides the piscina limosa, or purify ing reservoir usually placed at the mouth of each aqueduct, there were frequent castella, or wells along the line, which both aided in the process of purification, and permitted water to be drawn occasionally along the route, for the irrigation of fields and gardens, and the supply of baths. The main castellum was that in which the aqueduct terminated, and whence the water was distributed through the city. These were vast, solid, and stately architectural structures. The mass of ruins now called "The Trophies of Marius," from some very vague tradition, are undoubtedly the remains of a vast castellum, in which, according to the conjecture of Burgess, the Aqua Julia, and the Claudia, were received. The Piscina MirabileJ near Cumae, is a "stupendous structure of 200 feet in length, by 130 in

breadth, whose vaulted roof rests upon forty-eight immense pillars, disposed in rows, so as to form five aisles within the edifice, and sixty arches."

The castellaMvere of three kinds, public, private, and domestic.}: The public castella which received the water of the aqueduct, were such as have already been described, and from them distribution was made 1st., to the Praetorian:

camps 2d., to the fountains, and pools in the city 3d., the Munera, under which head ; ;

are comprised the places where the public shows and spectacles were given, such as the