It is carried alternately in that deep bed when the ground is high, and in a bank of clay when the ground is low 103 The stream is divided at a loch between Roma Vecchia and the Torre Fiscale ib. One branch follows the line of the great aqueducts towards Rome, in the bed of the Almo ib. It enters Rome in that bed, under the bridge on which the Porta Metronia stands ib. It then passes the Garden of Crassipes, now the Orto Botanico 104 —— turning to the north, under the Aventine, to the Piscina Publica ib. —— passes through the Circus Maximus, and under several mills ib. —— to the mouth of the river Almo in the Tiber, through an opening left for it in the Pulchrum Littus ib. This Aqueduct was made under Pope Calixtus II. in A.D. 1124 ib. Another branch of it is carried by the side of the other branch of the river Almo, in the valley of the Caffarella, and the other _specus_, which is open on the top, has lochs in it there 105 XVIII. AQUA FELICE, A.D. 1587. So called after Pope Sixtus V. (Felice Peretti) 106 Source under La Colonna ib. Reservoir made under Gregory XIII., A.D. 1572-1585 ib. The arcade and _specus_ were made under Sixtus V., but other reservoirs were not completed until Urban VIII., A.D. 1623-44 ib. The _fistula Urbana_ of marble ib. The piers and foundation of the old arcade used ib. The _specus_ enters Rome near the Porta Maggiore 107 The water is then divided into different branches ib. Junction of this arcade with the old one of the Claudia 108 From the Porta Maggiore the main line is carried upon the same high bank as the old Aqueducts ib. It turns at the Porta di S. Lorenzo 109 —— and is carried on an arcade to the great _agger_ on the Viminal, and to the fountain of the Termini, called that of Moses ib. SUMMARY. Frontinus mentions _nine_ Aqueducts 110 The Regionary Catalogue of the fourth century enumerates _nineteen_ Aquæ in Rome ib. Some of these were natural watercourses 111 Procopius in the sixth century mentions _fourteen_ only 112 LEVELS OF THE AQUEDUCTS 113 AQUEDUCTS.—LIST OF PLATES. PHOTO-ENGRAVINGS. PLATE