The archæology of Rome, Part 7

by John Henry Parker

The Great Drain.

There is considerable difficulty at the present time (in 1876) in obtaining correct information on the subject of the great drain, which carried off the water from the substructures. The entrance to it from the south-east end, under the entrance for animals, has been mentioned before, with the sluice-gate, which lifted up like a portcullis, and the grooves for it remain. Openings into it, covered with modern iron gratings, are seen in the floor of the passage, and across the mouth of it is an ancient iron grating. This great and deep drain carried the water in a straight line beyond the outer wall of the building, and just at this point a steam engine was placed in the years 1874 and 1875 to pump out the water, which gushed out of the earth a little further on, in the direction of the church of S. Clement, with a divergence to the south towards the Cœlian Hill. This water was very abundant, but it appeared more like the continuous stream of an aqueduct than a natural spring of water; it was at a very low level, quite 30 ft. underground. At a considerably higher level, and near the surface of the ground, was an aperture into the brick specus or conduit of an aqueduct of the third century, in which the water was flowing steadily along from west to east; this continued all the summer of 1874, and the water was always flowing. This aperture was closed in the summer of 1875, and the whole specus buried again; where the water was sent to is not known to any one but the persons employed, and they say that this water had little to do with the other water which they pumped out, although both were always good clear limpid streams of drinking water. The water was pumped out and conveyed 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.

Father Mullooly, the excellent Prior of S. Clement, says he has observed that the water under this church always rises and falls at the same time as that under the Colosseum, and he is convinced that they both come from the same source. It seemed probable that this source, or at least one of the sources of this water, is the great reservoir of the earliest aqueduct, the Aqua Appia, under the garden of the Villa Cœlimontana, formerly called Villa Mattei, which is now the property of the Baron Hoffman, at the west end of the Cœlian Hill, on a high level. The Baron wanted to make this old vaulted reservoir into a wine-cellar, but found it impossible to get rid of the water, which is always two or three feet deep, and as fast as he pumped it out it filled again to the same level, but no higher; this shews that there must be some outlet to it, but so deep underground that no one knows which way it goes. This old reservoir is nearly under the great reservoir of Nero for the Anio Novus, which was fifty feet higher, and carried on his arches, for which also the Arch of Dolabella was used as a substructure only. We have found in our examination of the aqueducts that the later ones always followed the same course as the earlier ones, not exactly over them, but by the side of them, each succeeding aqueduct being always on a higher level, and there is always a subterranean reservoir of one of the earlier aqueducts nearly under those of the later period. The Appia was made nearly four centuries before the Anio Novus, still it is very probable that the same plan was followed in both cases. We have found that the aqueduct of Claudius and Nero, called the Anio Novus, was divided into three branches at this point; one went straight on over the Palatine to the Capitoline Hill, another branch went to the left, or south, of the Aventine, and a third to the right, or north, to the Colosseum. It seems extremely probable that the same plan had been followed with the Appia, both were carried along the high ground of the Cœlian Hill as far as could be done, and then each was divided into three branches. We traced one branch of it over the Porta Capena to the Aventine and the Tiber; this is now necessarily out of use, the gate on the arch of which it was carried having been destroyed. A landslip in the garden of the Marchese Rappini, in February, 1876, between the Villa Cœlimontana and the Palatine, served to shew that a specus or conduit passed there, now also out of use. An excavation was made there in April of the same year, but all that came to light was a deep well, an ancient quarry of tufa, also at a great depth, and the specus of the aqueduct coming from the reservoir under the Claudium, called a vivarium, and going in the direction of the valley in which was the Porta Capena. This specus has been long out of use, and could not have had any connection with the flood in the Colosseum, which was the object of the search. The water conveyed in this specus originally must have been one of those that passed over the short agger of Servius Tullius from the Cœlian to the Aventine, found in the excavation of 1868, and traced also in 1876 in the cave under S. Sabba, by the side of the Aqua Appia, in the same tunnel, but in a terra-cotta pipe, not in the stone specus. The third branch, in the direction of the Colosseum, may still be in use, though so deep as to be unknown, supplying wells only, and this may be the one tapped by the workmen employed by Signor Rosa, and which now floods the Colosseum, and S. Clement’s also. The only outlet from a large reservoir, in which the water is always three feet deep, must afford a very abundant supply of water, and the account given by the workmen who made this branch of it agrees with this. They say it was a steady constant stream of water, and it did not gush out of the earth in the manner that a natural spring does; the spring must therefore be at some distance. If this view is correct, it would be comparatively easy to turn the stream into a drain under the Clivus Scauri, and into the one made by the Municipality about 1865, under the road near the church of S. Gregory, between the Cœlian and the Palatine, and to carry it in that manner to the Tiber.

It is however probable that this spring alone, which was only a subsidiary spring to the Appian aqueduct, is not sufficiently abundant to supply the quantity of water, which now rises to the height of about ten feet, or quite three metres, in the substructures of the Colosseum. There is another spring, or perhaps more than one, in the ancient stone quarry under the garden of the monks of SS. John and Paul, on the other side of the Clivus Scauri, on the site of the Claudium, or that square part of the Cœlian Hill which is nearest to the Colosseum. This site is marked on an old plan of Rome, of the sixteenth century, as a reservoir of water, and there are no less than ten wells that descend into this old stone quarry. In the eighteenth century, and down to the middle of the nineteenth, this was called a vivarium, and was supposed to be the place where the wild animals were kept for exhibitions in the Colosseum, but there is no visible communication from one to the other. A plan of the old quarry, which was made for this work some years since, shews that this was not a vivarium. There are three ponds, but perhaps only one spring of water in it, and if the outlet for this water was stopped, the whole of the quarry, or caves as they are called, would soon be full of water. It seems probable that this is the place from which the greater part of the water comes that floods both the Colosseum and the cave of Mithras, nearly under the church of S. Clement. It seems also quite practicable to remove the water by an iron pipe into the drain under the road between the Cœlian and the Palatine, made by the Municipality about 1866. The level of the quarry is eight metres above that of the Colosseum; the soil there is on the level of the arena, and that is seven metres above the original pavement; the water in the old quarry is therefore fifteen metres, or about 45 ft. above the level of the old drain of the Colosseum, and nearly six metres above the drain made by the Municipality.

This opportunity may be taken to say, that great credit is due to the Municipality of Rome for the energy and perseverance with which they have carried on an admirable system of new drainage for the city; and not only the new city on the hills on the site of the city of the Kings and of the Empire, but also of the modern city of the Popes, built in the swamp between the hills and the Tiber, the draining of which is by no means easy. Nothing can be better than the old Cloaca Maxima, which is still the chief drain to this part of Rome, or for that of part of the old city; it drains the water of the streams that run down from three hills, the Palatine, the Capitoline, and the Quirinal, on this side. But on the northern side of the Capitoline Hill, in which was the Campus Martius, the mediæval drains are by no means equally good with those of the Kings; the mouths of these drains are always open to the Tiber, and when there is a flood of the river the water runs up the drains, and the Pantheon, which stands on very low ground, is always the first place in Rome to be flooded. Surely a sluice-gate might be placed at the mouth of each drain, suspended from a bar at the top, and worked on pivots only, which would let the water out, but would not let any in, as in the common traps of a drain in daily use in England.

The Roman authorities say that the water of the Tiber would close the doors, and not let any of the water in the drain pass out, but if the door was placed obliquely, and let the water flow past it with as little pressure upon it as possible, the water in the drains, which runs rapidly and with considerable force, would very soon force open the door that was suspended at the mouth of it. Any embankment of the Tiber would be money thrown away; if the great engineers and architects who built the wall of Aurelian, could not make it secure on the bank of the Tiber, no modern engineers or architects will do so. We see that nearly the whole of the great wall of Aurelian, on the bank of the Tiber, has been swept away by the great floods; the substructures of the towers, under water, remain, and are visible when the water is low in the river, but all along the bank has been swept away. When the water rises at the rate of a foot in an hour, and continues to do so for twenty hours consecutively, and runs at the rate of nine or ten miles an hour, no wall can stand against it that offers any resistance to it; smooth walls parallel to the course of the river might stand, as the quay of the Ripa Grande does, because it offers no resistance to the water.

After the greater part of this chapter was written and in type, I thought it necessary to go to Capua and Pozzuoli again to examine the remains of these amphitheatres, and I did so in November, 1875; it was my intention at the same time to have gone to Pompeii, to examine the amphitheatre there also, but the weather was so bad at that time I found it quite impracticable to do so; I therefore did so in May, 1876, and I find that the amphitheatre at Pompeii is of the time of Sylla the Dictator, and that the arrangements are not the same as those of the Roman amphitheatre; there are no substructions under the arena, and it appears there never could have been any, as in the centre there is the top of an original well, and the floor seems always to have been of earth only; there are no preparations for Naumachia, and the dens for the wild beasts are on the same level as the arena, and behind the podium. In the principal entrances there are sockets for a wooden balustrade, to separate the people from the wild beasts. The corridor round at the back of these dens has the original walls of brickwork, of good hard bricks, but rather thick, somewhat similar to those of the Pantheon at Rome, but much thicker than those of the time of Nero; the brick vaults of this corridor, or passage under the lower gallery, are modern or mediæval repairs. Many of the seats have been preserved or restored, they are of stone of volcanic character, the stone of the country, in fact, but they are of a convenient height, and comfortable to sit upon, though closely packed; the seat is raised two or three inches above the place for the feet of those in the next seat above. The construction of the outer wall is of blocks of lava, about the shape of English bricks, but rather larger, and with opus reticulatum, the pattern of large size, enclosed in a sort of framework of these quasi-bricks, very similar to the Muro Torto at Rome. The fresco of the first century found on a wall here, and now preserved in the Museum at Naples[243], is a caricature of the building; and the vomitoria, which form a conspicuous object in the front of the picture, are greatly exaggerated, made much more lofty and more long and narrow than they really are. They are said to be the ladies’ entrance to their gallery, which was the upper gallery at the back; but as the slope was very gradual, and the building not nearly so high as the Colosseum, they would be able to see perfectly well, and their entrance and exit being entirely on the exterior of the building, while that of the men was from the interior, was a very convenient arrangement. It seems probable that Scaurus, the step-on of Sylla, had seen this building in progress, and as the Romans always had the idea of making Rome the most magnificent city in the world, he built the far more magnificent amphitheatre in Rome; but as the upper part was built of wood, though magnificently decorated with columns of marble, of glass, and of gilt wood, as we have said, it seems to have offended the Republican notions of the Romans, and this upper part was entirely destroyed, or this may have happened from an accidental fire; but as the substructures were of tufa they were everlasting, as Pliny says, and they still remain as the principal foundations of the Colosseum, with brick walls and galleries erected upon them in the time of Nero, and the whole enclosed by the magnificent stone front and double corridors of the Flavian Emperors.