Description of Plate XXI.
SECTIONS OF THE SPECUS OF EACH OF THE FIFTEEN AQUEDUCTS OF ROME.
The names of each are given under the section of it, and it will be observed that no two are alike; this was no doubt done in order that the workmen might always know which aqueduct each belonged to, at the points where they cross each other, so that if there was any obstacle in one of them it might be readily removed. Some of those which came from a clay soil, as the Appia and the Virgo, were liable to get choked up by the quantity of deposit left by the water, and it was necessary to have them cleared out from time to time, as is still the case with the Virgo, now called the Aqua di Trevi. One of the small streams that were collected to form the Aqua Hadriana, which comes from near Gabii, was a petrifying spring, which quite choked up the specus in the course of a century. It was restored by Alexander Severus, but the same water seems still to have been used. The Aqua Felice comes from the same sources, but the petrifying spring was carefully excluded, and now runs in a ditch, giving a coat of stone to the sticks and the weeds.
PLAN OF THE AQUEDUCTS.
ON THE CŒLIAN.
AQUEDUCTS ON THE CŒLIAN AND ESQUILINE LEADING TO THE COLOSSEUM.
PLAN OF THE AQUEDUCTS.
On the Cœlian[237].
Three branches diverge from the great central reservoir at the Arch of Dolabella,—one goes straight on, nearly due north to the Palatine, the second north-east to the Colosseum, and the third west to the Aventine.
And on the Esquiline.