The archæology of Rome, Part 8

by John Henry Parker

This calculation illustrates his mode of computation from absolute measure of the water; but the ordinary way was to affix the moduli, which were of brass, or rather of bronze, to certain openings. Provided the modulus was placed perfectly level, the water flowed at its ordinary rate; and when the moduli were sufficient to prevent the water rising in the reservoir or channel, and, on the other hand, not too numerous or too large to reduce the mean level of the water, the sum of them represented the amount of water.

We next come to the question of distribution. On examining the registers, Frontinus says that he found that there were assigned to the nine aqueducts 12,755 quinaries; but it appeared that the distribution amounted to 13,470 quinaries. To account for this discrepancy, the whole were re-measured. In the annexed table the measures of each aqueduct are given separately, and by adding together the results of each, as calculated from the data which Frontinus gives of the water measured at the head, the total, as the table shews, comes to 24,413 quinaries. The fact was that in process of time some of the channels had fallen into decay, and the water was wasted. In other and more numerous cases, it had been abstracted by persons for their own use without authority; in addition to which there were no doubt errors in the computation, which had crept into the books, and if we are to believe Frontinus, these errors had been turned to the profit of his predecessors.

In the table of distribution will be seen the number of quinaries distributed outside the wall of the city; next, the Regiones which they serve within the city; thirdly, the measure of water so distributed within the city, and the number of castella, or reservoirs, used for that purpose. These reservoirs, at least such as remain, will be described in the several Regiones in which they occur. That over the arch of Dolabella on the Cœlian Hill, and the so-called Castellum Aquæ Juliæ on the Esquiline, are the most prominent. Many, no doubt, were of much smaller size, and merely large cisterns, as the total number was 247.

The supply of 13,470 quinaries is thus accounted for. Outside Rome 3,164 quinaries were distributed, inside 10,306; of that outside Rome 1,718 quinaries were used “in the name of the Emperor,” that is, to supply the imperial villas and gardens, &c., while 2,345 were charged to private persons. Inside Rome 1,707 were charged to the Emperor for his palaces, &c., while private persons used 3,847 quinaries, leaving 4,401 quinaries, which were for the “Public Service.” These, together, account for the 9,955 distributed within Rome.

In the details of the distribution, we learn how much water was employed in the palaces, &c., in the service of the Emperor and his household (nomine Cæsaris), how much was carried into houses for the use of private persons, and how much was used in public buildings and the public reservoirs or fountains which were established in all convenient positions, and generally accessible to the population.

It may, perhaps, be interesting to examine more carefully the distribution for the “Public Service.” We have four classes of recipients, and we know from Frontinus how much was served to each class from each aqueduct. There were first of all 19 castra or barracks, in which the army were kept when not out on service, and in which also the guards were stationed. These required in all 279 quinaries. There were next, 95 different Public Establishments which used 2,401 quinaries, and 39 theatres and places of entertainment (munera) which used 386 more. Lastly, there were 591 open reservoirs (lacus) for the service of all comers, using 1,335 quinaries. These reservoirs were what we usually speak of as fountains, and some hundreds are in use to this day, many probably on the site of the older ones. There were very stringent laws respecting their use. Heavy penalties were inflicted upon anyone dipping a dirty bucket or other vessel into the reservoir; there were also laws respecting the “overflow,” as the fountains of course were constantly running. These were the most important to keep in order, as all the poorer classes depended entirely upon them for their supply of water.

The more wealthy had water brought into their own private reservoir in the court, with buckets and windlasses for drawing the water to the upper story, and this is the case to the present day[159].

These details, while giving us an insight into the social state of the city, go to shew how thoroughly the supply of the water was under control. The pipes supplying every one of these 744 points of distribution were all registered, and their sizes being known, the system of computation, as explained by Frontinus, was brought into play: thus every part was checked, and any irregularity could be traced to its source.

It may be asked what amount of supply, in gallons, would the water represent, in order that a comparison can be made between the supply of towns at the present time, and that of Rome at the time at which Frontinus wrote. The answer is not easy. As said before, we have not sufficient data for an accurate determination; still we may attempt an approximate estimate. It is easy to compute the section of water given by the 24,805 quinaries. This being just upon 120 square feet, we can form some notion of the vast quantity, if we picture to ourselves a stream twenty feet wide by six feet deep, constantly pouring into Rome at a fall six times as rapid as that of the river Thames. It has been computed by a French engineer that, together with one or two additional aqueducts which were added between the time of Trajan and Aurelian, the supply of water to Rome was 332,306,624 gallons daily. If we assume the population to have been a million souls—and it is scarcely probable that there were more—we find that the rate was 332 gallons per diem for each person. In our own day we consider 40 gallons sufficient, and many think this excessive, including the use of water in manufactures, &c. No wonder, with the facilities for drainage which the rapid Tiber afforded, and with this plentiful supply of really good water, the great city was rendered, in spite of overcrowding and an unhealthy situation as regards its neighbourhood, comparatively free from those epidemics which are so fatal in all densely-populated towns.