Note 25 — Chapter IV · PART I. THE AQUEDUCTS.

There are considerable remains of two large reservoirs in a garden just outside of the boundary-wall of the Sessorium, which wall is of the time of S. Helena, on its western side. Some excavations made in them in 1869 under my direction shewed that they went to a great depth, the workmen being stopped by water. These two great reservoirs, so close together in the line of the Aqua Appia, seem to have been the Gemelli mentioned by Frontinus. From this point the specus can be traced along the Cœlian, and the reservoirs are below the level of that specus (infra specum veterem).—F. ii. 65.