in an open channel, parallel to the building, to the Arch of Constantine, where it made a small flood during all the spring of 1875, and was then carried into a modern drain under the road between the Cœlian and the Palatine, after passing over the road and washing the base of the Arch of Constantine for several months. The old drain, at a great depth, was traced the whole length of the Colosseum, parallel to it, close under the foot of that part of the Cœlian Hill on which the Claudium stood, and under which the two _piscinæ_, one of the time of Nero, the other of Alexander Severus, have been mentioned. The workmen employed to clear out the old drain were alarmed at the great depth; an enormous quantity of earth had been thrown upon it, and they were afraid of its falling in behind them, and blocking up their only mode of exit; deep wells were made down into it, but after they had gone nearly as far as the Arch of Constantine at this depth, they were stopped for want of air. Another well, or air-pipe, was necessary, but the works were then all suspended for want of funds. It is known that an ancient drain, at a great depth, went under the road, and at a much lower level than a modern drain, which passes near the monastery or church of S. Gregory on the Cœlian, between that and the Palatine; and there can be little doubt that this was a continuation of the same drain, and that it might all be cleared out and repaired, but unless air-pipes can be put down by boring the expense would be enormous. Another small ancient drain has also been found coming from the Summa Sacra Via, apparently for the fountains at the four corners of the Porticus Liviæ. The workmen had been told that they were to find the great drain passing under that part, and going on to the Cloaca Maxima in the Forum Romanum, but this could not be found, and did not appear practicable.