by Frontinus
[8] The Censors, Gnaeus Servilius Caepio and Lucius Cassius Longinus, called Ravilla, in the year 627 after the founding of the City, in the consulate of Marcus Plautus Hypsaeus and Marcus Fulvius Flaccus, had the water called Tepula brought to Rome and to the Capitol, from the estate of Lucullus, which some persons hold to belong to Tusculan territory. The intake of Tepula is at the tenth milestone on the Latin Way, near a cross-road, two miles to the right as you proceed from Rome … From that point it was conducted in its own channel to the City.
[9] Later … in the second consulate of the Emperor Caesar Augustus, when Lucius Volcatius was his colleague, in the year 719 after the foundation of the City, [Marcus] Agrippa, when aedile, after his first consulship, took another independent source of supply, at the twelfth milestone from the City on the Latin Way, on a cross-road two miles to the right as you proceed from Rome, and also tapped Tepula. The name Julia was given to the new aqueduct by its builder, but since the waters were again divided for distribution, the name Tepula remained. The conduit of Julia has a length of 15,426½ paces; 7,000 paces on masonry above ground, of which 528 paces next the City, beginning at the seventh milestone, are on substructures, the other 6,472 paces being on arches. Past the intake of Julia flows a brook, which is called Crabra. Agrippa refrained from taking in this brook either because he had condemned it, or because he thought it ought to be left to the proprietors at Tusculum, for this is the water which all the estates of that district receive in turn, dealt out to them on regular days and in regular quantities. But our water-men, failing to practise the same restraint, have always claimed a part of it to supplement Julia, not, however, thus increasing the actual flow of Julia, since they habitually exhausted it by diverting its waters for their own profit. I therefore shut off the Crabra brook and at the Emperor’s command restored it entirely to the Tusculan proprietors, who now, possibly not without surprise, take its waters, without knowing to what cause to ascribe the unusual abundance. The Julian aqueduct, on the other hand, by reason of the destruction of the branch pipes through which it was secretly plundered, has maintained its normal quantity even in times of most extraordinary drought. In the same year, Agrippa repaired the conduits of Appia, Old Anio, and Marcia, which had almost worn out, and with unique forethought provided the City with a large number of fountains.
[10] The same man, after his own third consulship, in the consulship of Gaius Sentius and Quintus Lucretius, twelve years after he had constructed the Julian aqueduct, also brought Virgo to Rome, taking it from the estate of Lucullus. We learn that June 9 was the day that it first began to flow in the City. It was called Virgo, because a young girl pointed out certain springs to some soldiers hunting for water, and when they followed these up and dug, they found a copious supply. A small temple, situated near the spring, contains a painting which illustrates this origin of the aqueduct. The intake of Virgo is on the Collatian Way at the eighth milestone, in a marshy spot, surrounded by a concrete enclosure for the purpose of confining the gushing waters. Its volume is augmented by several tributaries. Its length is 14,105 paces. For 12,865 paces of this distance it is carried in an underground channel, for 1,240 paces above ground. Of these 1,240 paces, it is carried for 540 paces on substructures at various points, and for 700 paces on arches. The underground conduits of the tributaries measure 1,405 paces.
[11] I fail to see what motive induced Augustus, a most sagacious sovereign, to bring in the Alsietinian water, also called Augusta. For this has nothing to commend it, — is in fact positively unwholesome, and for that reason is nowhere delivered for consumption by the people. It may have been that when Augustus began the construction of his Naumachia, he brought this water in a special conduit, in order not to encroach on the existing supply of wholesome water, and then granted the surplus of the Naumachia to the adjacent gardens and to private users for irrigation. It is customary, however, in the district across the Tiber, in an emergency, whenever the bridges are undergoing repairs and the water supply is cut off from this side of the river, to draw from Alsietina to maintain the flow of the public fountains. Its source is the Alsietinian Lake, at the fourteenth milestone, on the Claudian Way, on a cross-road, six miles and a half to the right. Its conduit has a length of 22,172 paces, with 358 paces on arches.
[12] To supplement Marcia, whenever dry seasons required an additional supply, Augustus also, by an underground channel, brought to the conduit of Marcia another water of the same excellent quality, called Augusta from the name of its donor. Its source is beyond the springs of Marcia; its conduit, up to its junction with Marcia, measures 800 paces.
[13] After these aqueducts, Gaius Caesar, the successor of Tiberius, in the second year of his reign, in the consulate of Marcus Aquila Julianus and Publius Nonius Asprenas, in the year 791 after the founding of the City, began two others, inasmuch as the seven then existing seemed insufficient to meet both the public needs and the luxurious private demands of the day. These works Claudius completed on the most magnificent scale, and dedicated in the consulship of Sulla and Titianus, on the 1st of August in the year 803 after the founding of the City. To the one water, which had its sources in the Caerulean and Curtian springs, was given the name Claudia. This is next to Marcia in excellence. The second began to be designated as New Anio, in order the more readily to distinguish by title the two Anios that had now begun to flow to the City. To the former Anio the name of “Old” was added.
[14] The intake of Claudia is at the thirty-eighth milestone on the Sublacensian Way, on a cross-road, less than three hundred paces to the left. The water comes from two very large and beautiful springs, the Caerulean, so designated from its appearance, and the Curtian. Claudia also receives the spring which is called Albudinus, which is of such excellence that, when Marcia, too, needs supplementing, this water answers the purpose so admirably that by its addition there is no change in Marcia’s quality. The spring of Augusta was turned into Claudia, because it was plainly evident that Marcia was of sufficient volume by itself. But Augusta remained, nevertheless, a reserve supply to Marcia, the understanding being that Augusta should run into Claudia only when the conduit of Marcia would not carry it. Claudia’s conduit has a length of 46,606 paces, of which 36,230 are in a subterranean channel, 10,176 on structures above ground; of these last there are at various points in the upper reaches 3,076 paces on arches; and near the City, beginning at the seventh milestone, 609 paces on substructures and 6,491 on arches.
[15] The intake of New Anio is at the forty-second milestone on the Sublacensian Way, in the district of Simbruvium. The water is taken from the river, which, even without the effect of rainstorms, is muddy and discoloured, because it has rich and cultivated fields adjoining it, and in consequence loose banks. For this reason, a settling reservoir was put in beyond the inlet of the aqueduct, in order that the water might settle there and clarify itself, between the river and the conduit. But even despite this precaution, the water reaches the City in a discoloured condition whenever there are rains. It is joined by the Herculanean brook, which has its source on the same Way, at the thirty-eighth milestone, opposite the springs of Claudia, beyond the river and the highway. This is naturally very clear, but loses the charm of its purity by admixture with New Anio. The conduit of New Anio measures 58,700 paces, of which 49,300 are in an underground channel, 9,400 paces above ground on masonry; of these, at various points in the upper reaches are 2,300 paces on substructures or arches; while nearer the City, beginning at the seventh milestone, are 609 paces on substructures, 6,491 paces on arches. These are the highest arches, rising at certain points to 109 feet.
[16] With such an array of indispensable structures carrying so many waters, compare, if you will, the idle Pyramids or the useless, though famous, works of the Greeks!
[17] It has seemed to me not inappropriate to include also a statement of the lengths of the channels of the several aqueducts, according to the kinds of construction. For since the chief function of this office of water-commissione
r lies in their upkeep, the man in charge of them ought to know which of them demand the heavier outlay. My zeal was not satisfied with submitting details to examination; I also had plans made of the aqueducts, on which it is shown where there are valleys and how great these are; where rivers are crossed; and where conduits laid on hillsides demand more particular constant care for their maintenance and repair. By this provision, one reaps the advantage of being able to have the works before one’s eyes, so to speak, at a moment’s notice, and to consider them as though standing by their side.
[18] The several aqueducts reach the City at different elevations. In consequence certain ones deliver water on higher ground, while others cannot rise to the loftier points; for the hills have gradually grown higher with rubbish in consequence of frequent conflagrations. There are five whose head rises to every point in the City, but of these some are forced up with greater, others with lesser pressure. The highest is New Anio; next comes Claudia; the third place is taken by Julia; the fourth by Tepula; the last by Marcia, although at its intake this mounts even to the level of Claudia. But the ancients laid the lines of their aqueducts at a lower elevation, either because they had not yet nicely worked out the art of levelling, or because they purposely sunk their aqueducts in the ground, in order that they might not easily be cut by the enemy, since frequent wars were still waged with the Italians. But now, whenever a conduit has succumbed to old age, it is the practice to carry it in certain parts on substructures or on arches, in order to save length, abandoning the subterranean loops in the valleys. The sixth rank in height is held by Old Anio, which would likewise be capable of supplying even the higher portions of the City, if it were raised up on substructures or arches, wherever the nature of the valleys and low places demands. Its elevation is followed by that of Virgo, then by that of Appia. These, since they were brought from points near the City, could not rise to such high elevations. Lowest of all is Alsietina, which supplies the ward across the Tiber and the very lowest districts.
[19] Of these waters, six are received in covered catch-basins, this side the seventh milestone on the Latin Way. Here, taking fresh breath, so to speak, after the run, they deposit their sediment. Their volume also is determined by gauges set up at the same point. Three of these, Julia, Marcia, and Tepula, are carried by the same arches from the catch-basins onward. Tepula, which, as we have above explained, was tapped and added to the conduit of Julia, now leaves the basin of this same Julia, receives its own quota of water, and runs in its own conduit, under its own name. The topmost of these three is Julia; next below is Tepula; then Marcia. These flowing [under ground] reach the level of the Viminal Hill, and in fact even of the Viminal Gate. There they again emerge. Yet a part of Julia is first diverted at Spes Vetus, and distributed to the reservoirs of Mount Caelius. But Marcia delivers a part of its waters into the so-called Herculanean Conduit, behind the Gardens of Pallas. This conduit, carried along the Caelian, affords no service to the occupants of the hill, on account of its low level; it ends beyond the Porta Capena.
[20] New Anio and Claudia are carried together from their catch-basins on lofty arches, Anio being above. Their arches end behind the Gardens of Pallas, and from that point their waters are distributed in pipes to serve the City. Yet Claudia first transfers a part of its waters near Spes Vetus to the so-called Neronian Arches. These arches pass along the Caelian Hill and end near the Temple of the Deified Claudius. Both aqueducts deliver the volume which they receive, partly about the Caelian, partly on the Palatine and Aventine, and to the ward beyond the Tiber.
[21] Old Anio, this side the fourth milestone, passes under New Anio, which here shifts from the Latin to the Labican Way; it has its own catch-basin. Then, this side the second milestone, it gives a part of its waters to the so-called Octavian Conduit and reaches the Asinian Gardens in the neighbourhood of the New Way, whence it is distributed throughout that district. But the main conduit, which passes Spes Vetus, comes inside the Esquiline Gate and is distributed to high-lying mains throughout the City.
[22] Neither Virgo, nor Appia, nor Alsietina has a receiving reservoir or catch-basin. The arches of Virgo begin under the Lucullan Gardens, and end on the Campus Martius in front of the Voting Porticoes. The conduit of Appia, running along the base of the Caelian and Aventine, emerges, as we have said above, at the foot of the Publician Ascent. The conduit of Alsietina terminates behind the Naumachia, for which it seems to have been constructed.
[23] Since I have given in detail the builders of the several aqueducts, their dates, and, in addition, their sources, the lengths of their channels, and their elevations in sequence, it seems to me not out of keeping to add also some separate details, and to show how great is the supply which suffices not only for public and private uses and purposes, but also for the satisfaction of luxury; by how many reservoirs it is distributed and in what wards; how much water is delivered outside the City; how much is used for water-basins, how much for fountains, how much for public buildings, how much in the name of Caesar, how much for private consumption. But before I mention the names quinaria, centenaria, and those of the other ajutages by which water is gauged, I deem it appropriate to state what is their origin, what their capacities, and what each name means; and, after setting forth the rule according to which their proportions and capacities are computed, to show in what way I discovered their discrepancies, and what course I pursued in correcting them.
[24] The ajutages to measure water are arranged according to the standard either of digits or of inches. Digits are the standard in Campania and in most parts of Italy; inches are the standard in … Now the digit, by common understanding, is 1/16 part of a foot; the inch 1/12 part. But precisely as there is a difference between the inch and the digit, just so the standard of the digit itself is not uniform. One is called square; another, round. The square digit is larger than the round digit by 3/14 of its own size, while the round is smaller than the square by 3/11 of its size, obviously because the corners are cut off.
[25] Later on, an ajutage called a quinaria came into use in the City, to the exclusion of the former measures. This was based neither on the inch, nor on either of the digits, but was introduced, as some think, by Agrippa, or, as others believe, by plumbers at the instance of Vitruvius, the architect. Those who represent Agrippa as its inventor, declare it was so designated because five small ajutages or punctures, so to speak, of the old sort, through which water used to be distributed when the supply was scanty, were now united in one pipe. Those who refer it to Vitruvius and the plumbers, declare that it was so named from the fact that a flat sheet of lead 5 digits wide, made up into a round pipe, forms this ajutage.º But this is indefinite, because the plate, when made up into a round shape, will be extended on the exterior surface and contracted on the interior surface. The most probable explanation is that the quinaria received its name from having a diameter of 5/4 of a digit, a standard which holds in the following ajutages also up to the 20-pipe, the diameter of each pipe increasing by the addition of ¼ of a digit. For example the 6-pipe is six quarters in diameter, a 7-pipe seven quarters, and so on by a uniform increase up to a 20-pipe.
[26] Every ajutage, now, is gauged either by its diameter or circumference, or by its area of clear cross-section, from any of which factors its capacity becomes evident. That we may distinguish the more readily between the inch ajutage, the square digit, the circular digit, and the quinaria itself, use must be made of the value of the quinaria, the ajutage which is most accurately determined and best known. Now the inch ajutage, has a diameter of 1⅓ digits. Its capacity is [slightly] more than 1⅛ quinariae, i.e., 1½ twelfths of a quinaria plus 3/288 plus ⅔ of 1/288 more. The square digit, reduced to the circle is 1 digit plus 1½ twelfths of a digit plus 1/72 in diameter; its capacity is 10/12 of a quinaria. The circular digit is 1 digit in diameter; its capacity is 7/12 plus ½ twelfth plus 1/72 of a quinaria.