Porticoes. The conduit of Appia, running along the base of the Caelian and Aventine, emerges, as we have said above,[1] at the foot of the Publician Ascent. The conduit of Alsietina terminates behind the Naumachia, for which it seems to have been constructed.
Since I have given in detail the builders of the several aqueducts, their dates, and, in addition, their sources, the lengths of their channels, and their elevations in sequence, it seems to me not out of keeping to add also some separate details, and to show how great is the supply which suffices not only for public and private uses and purposes, but also for the satisfaction of luxury; by how many reservoirs it is distributed and in what wards; how much water is delivered outside the City; how much in the City itself; how much of this latter amount is used for water-basins, how much for fountains, how much for public buildings, how much in the name of Caesar, how much for private consumption. But before I mention the names quinaria, centenaria, and those of the other ajutages[2] by which water is gauged, I deem it appropriate to state what is their origin, what their capacities, and what each name means; and, after setting forth the rule according to which their proportions and capacities are computed, to show in what way I discovered their discrepancies, and what course I pursued in correcting them.
The ajutages to measure water are arranged according to the standard either of digits or of inches.[3] Digits are the standard in Campania and
- ↑ Cf. 5.
- ↑ The ajutage was the nozzle, fitted to the water-pipe. The size and character of the ajutage, therefore, were important factors in the measurement of the water discharged. The ajutage was gauged according to various principles. Cf. 26.
- ↑ One of the most serious abuses practised by the water-men at Rome was connected with the size of the pipes used in the receiving and the distribution of water. Cf. 112, 113, 114. Since the size and position (cf. 36) of the ajutage controlled the amount discharged, it was necessary to know the exact capacity of each type, and Frontinus, therefore, enumerates these first of all.
