Tale giganteum Græcia laudat opus.
Intercepta tuis conduntur flumina muris;
Consumunt totos celsa lavacra lacus.”
(Cl. Rutilii Itiner., l. 1, v. 97. and following.)
[209] “In formis autem Romanis utrumque præcipuum est ut fabrica sit mirabilis et aquarum salubritas singularis. Quod enim illuc flumina quasi constructis montibus perducuntur, naturales credas alveos soliditates saxorum, quando tantus impetus fluminis tot sæculis firmiter potuit sustineri. Cavati montes plerunque subruunt, meatus torrentium dissipantur, et opus illud veterum non destruitur, si industria suffragante servetur.”—(Cassiodori Variar., l. vii. c. 6.)
[210] It is possible that the number of nineteen was made up by adding the different branches that supplied the Thermæ of the later Emperors, (Septimius) Severus, Antoninus, Alexander (Severus), (Aurelius) Commodus, Constantinus.
To these must now be added the two modern aqueducts, the Marrana and Aqua Crabra [XVII.], united and brought through Rome in the twelfth century in the bed of that branch of the river Almo, and the Aqua Felice [XVIII.], made in the sixteenth; also the Aqua Marcia-Pia, made between 1860 and 1870, which now brings the water of the Aqua Marcia into Rome by a different line.
[211] This was also the principal gate of the Sessorian Palace, and was sometimes called the Porta Sessoriana.
[212] See Diagrams [III.] and [XIX.]
[213] See the Plans and Sections of this, [Plate XXI.]