III. The Appia under S. Sabba. The specus in an old stone quarry on the Pseudo-Aventine. IV. Mouth of the Appia under the Aventine, and at the Porta Trigemina, now in a Cave under S. Alexio and the Priorato. V. Aqua Appia—Reservoir in Garden of the Sessorium, now of S. Croce, called the Thermæ of S. Helena. VI. Anio Vetus.—Reservoir near the Porta Furba. VII. Loch in the Aqua Julia, near the Imperial Villa, called the Sette Bassi. VIII. Aqueducts and River Almo, near the Porta Furba. IX. The Seven Aqueducts at the Tor Fiscale. Plan and Section. X. Piscina of the Anio Novus, entering Rome through a tower in the wall of Aurelian in the garden of the Sessorium. XI. The Aqueducts at the Porta Maggiore and the Porta Tiburtina. Plan and Section. XII. Nymphæum, where the Trophies of Marius were hung. Plan and Section. XIII. River Almo—Division into two Branches, now a Loch of the Marrana. XIV. River Almo, now the Marrana.—Entrance into Rome under the Porta Metronia. XV. River Almo—Mouth in the Pulchrum Littus. View. XVI. —— Plan. XVII. Sources of the Aqua Appia, near the bank of the river Anio, in a very ancient stone quarry. XVIII. Aqua Appia, or Appian Aqueduct, crossing the valley from the Cœlian to the Aventine upon the short Agger of Servius Tullius, and over the Porta Capena. XIX. Plan and Sections of the Aqueducts in a Cave in the Aventine, under S. Sabba, with the Excavations made in 1875 and 1876. XX. Plan and Section of the Aqueducts, from the great Reservoirs on the Cœlian Hill, near the Arch of Dolabella and the Claudium, to the Colosseum, and to the Drain under the road from the Arch of Constantine to the Clivus Scauri. XXI. Sections of the Specus or Conduits of fifteen different Aqueducts. Plan of the Aqueducts on parts of the Cœlian and the Esquiline Hills, from the great Reservoirs and Piscinæ called Sette Sale, on the Esquiline, to the Colosseum; and the Three Branches from the great Reservoir on the Cœlian, and over the Arch of Dolabella, and the Piazza della Navicella, to the Aventine, the Palatine, and the Colosseum. Map of the Aqueducts on the Eastern side of Rome, from their Sources above Subiaco, and on the bank of the river Anio, to Rome, and their mouths in the Tiber. —— Western side of Rome, from their Sources in the lakes on the hills, called Alseatina and Sabatina, or Anguillara. CHAPTER IV. PART I. THE AQUEDUCTS.