+------------+--------+----------+----------+ | | | Total |Length of | | Name. | Date. |Length in |Arches in | | | B.C. | Miles. | Miles. | +------------+--------+----------+----------+ |Appia | 312 | 11 | Little | |Vetus | 272-264| 43 | ” | |Marcia | 145 | 61 | 12 | |Tepula | 126 | 13 | Little | |Julia | 34 | 15 | 6 | |Virgo | 21 | 14 | Little | | | | | | | | A.D. | | | |Alsietina | 10 | 22 | Little | |Augusta | 10 | 6 | ” | |Claudia | 50 | 46 | 10 | |Anio Novus | 52 | 58 | 9 | |Triana | 109 | 42 | Little | |Alexandrina | 226 | 15 | 7 | | +--------+----------+----------+ | Totals | 346 | 44 | +------------+--------+----------+----------+ =34. Intakes and Settling-basins.=—The preceding brief descriptions of the old Roman aqueducts give but a superficial idea of the real features of those great works and of the system of water-supply of which they were such essential portions. Enough has been shown, however, to demonstrate conclusively that the engineers and constructors of old Rome were men who, on the one hand, possessed a high order of engineering talent and, on the other, ability to put in place great structures whose proportions and physical characteristics have commanded the admiration of engineers and others from the time of their completion to the present day. If a detailed statement were to be made in regard to the water-supply of ancient Rome, it would appear that much care was taken to insure wholesome and potable water. At the intakes of a number of the aqueducts, reservoirs or basins were constructed in which the waters were first received and which acted as settling-basins, so that as much sedimentation as possible might take place. Similar basins (picinæ) were also constructed at different points along the aqueducts for the same purpose and for such other purposes as the preservation of the water in a portion of the aqueduct in case another portion had to be repaired or met with an accident which for the time being might put it out of use. These basins were usually constructed of a number of apartments, the water flowing from one to the other, very much as sewage in some sewage-disposal works flows at the present time through a series of settling-basins. The object of these picinæ was the clearing of the water by sedimentation. Indeed there was in some cases a use of salt in the water to aid in clarifying it. This is an early type of the modern process of clarifying water by chemical precipitation, not the best of potable water practice, but one that is sometimes permissible.