I. AQUA APPIA. Passages from Frontinus 3 Sources in the Lucullan fields 4 —— near the old Via Prænestina 5 The course underground 6 It entered Rome at the north-east end of the Sessorium ib. —— passed along the Cœlian Hill ib. Reservoir in the garden of the Villa Cœlimontana, now the Arch of Dolabella 7 It crossed the valley to the Aventine on an ancient earthwork, near the Porta Capena 8 to the Piscina Publica 9 Under the Aventine the _Specus_ is visible in a stone quarry nearly under S. Sabba ib. Wells to descend into it ib. The branch added by Augustus entered Rome in the garden of the Sessorium 11 —— near the Gemelli ib. Torquatian and Pallantian gardens ib. II. ANIO VETUS. Passages from Frontinus 13 Sources—a branch from the river Anio ib. _Specus_ in the cliff of the valley 14 —— visible in the “Valley of the Arches” above Tivoli ib. —— and in the promenade of Carciano below it 15 —— Its course underground 16 Piscinæ at the fourth, and at the second, mile from Rome, on the Via Latina ib. Crossing of the Aqueducts at the Torre Fiscale 17 Castellum Aquæ near the Porta Furba, two miles from Rome 18 —— near the Via Appia Nova ib. The _Specus_ faced with _Opus Reticulatum_ 19 _Specus_, or _spes_ (?) _vetus_, on the high banks ib. Another branch on the bank near the Wall of Rome 20 And another branch along the Cœlian, and passing near the Port Capena, to the Aventine 21 Appendix, _Spē_ or _Spc̄_, _Spes_ (?) or _Specus_ (?) 22 —— Facsimile from MS. at Monte Cassino 26 Passages relating to the word _Specus_ 27-31 III. AQUA MARCIA. Passages from Frontinus 32