The water for the aqueducts of Rome was chiefly drawn from the river Anio, or from springs or tributary streams that fell into that river. It rises in the high mountains above Subiaco, which are generally covered with snow for the greater part of the year, and the supply of water never fails entirely, though it is not always equally abundant. It is generally a clear, bright mountain stream, coming through rocks, but it is liable to sudden and violent floods, which bring down a great deal of mud, and therefore great precautions are taken for filtering it. The latest and most important of the great aqueducts were the Claudia and Anio Novus; the latter was the most abundant of all, being in fact a branch of the river compelled to pass through Rome by clever engineering. A series of great lochs was made by building dams across the river, with cascades from one to another. There were three of these about two miles above Subiaco, and about forty-two miles from Rome. The uppermost one of them is seen in the upper part of the plate, but in the third loch, the lowest of the three (shewn in the lower part of the plate), the bed of the river is so deep, that the water is not seen. The country through which it passes is celebrated as among the most beautiful in Italy. PLATE IV. [Illustration: AQUEDUCTS ABOVE SUBIACO ANIO NOVUS, THE THIRD LOCH ANIO NOVUS, SPECUS CUT IN THE CLIFF] 1. ANIO NOVUS, THE THIRD LOCH, as seen from below, where the dam, that formerly kept up the water and formed a great cascade, has been thrown down, and appears only as rocks in the stream; the modern bridge seen in this view is built upon the two ends of the old dam. 2. ANIO NOVUS, SPECUS. The _specus_ is here a tunnel cut in the cliff, on the side of the valley on which the town of Subiaco stands; it is six feet high, and only eighteen inches wide (an opening into it may be seen in the cliff, on the left-hand side of the view). The round tower, seen on the right, is that of the Villa Gori, about a mile above Subiaco. PLATE V. AQUEDUCTS ABOVE SUBIACO—ANIO NOVUS, CASTELLUM. [Illustration: AQUEDUCTS ABOVE SUBIACO ANIO NOVUS, CASTELLUM LINE OF THE SPECUS OF ANIO NOVUS _Photogravure Dujardin, Paris_] This is the loch below the modern bridge, which is made upon the remains of the old dam across the river, destroyed in the fourteenth century by making a hole at the bottom to let the water escape from a flood in the upper country. The force of the water once let loose soon destroyed the dam, and the large stones of which it was built are still lying as rocks in the river, and are seen in the photograph and the photo-engraving.