Category Water Engineering in Ancient Civilizations. 5,000 Years of History

The water mill, the first energy source to replace muscle power, appears in the Hellenistic cultural sphere at the end of the 2nd or beginning of the 1st century BC. The region of origin of this important invention, somewhere in Asia, is not well known. The first traces are claimed to be from the kingdom of Pontus, at Cabeira, by Strabo (who is a native of that region), in the proximity of the new palace of Mithridatus VII Eupator, king of Pontus from 111 to 63 BC. He fought against the Roman expansion in the region, but was finally defeated by Pompey in 63 BC.

“… at their junction (i. e. of the two rivers Lycos and Iris) is situated a city which the first man who subjugated it called Eupatoria after his own name, but Pompey found it only half-fin­ished and added to it territory and settlers, and called it Magnopolis. Now this city is situat­ed in the middle of the plain, but Cabeira is situated close to the very foothills of the Paryadres mountains about one hundred and fifty stadia farther south than Magnopolis, the same dis­tance that Amaseia^1 is farther west than Magnopolis. It was at Cabeira that the palace of

Mithridates was built, and also the water-mill; and here were the zoological gardens, and, near

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by, the hunting grounds, and the mines.”

Another piece of written evidence, essentially from the same time as the text of Strabo, is attributed to Antipatros of Thessaly. It speaks poetically of the new pleasures to be enjoyed by the miller, liberated by hydraulics from the need to turn the mill with his own muscles. It also suggests that this is a recent invention:

“Women who toil at the querns, cease now your grinding;

Sleep late though the crowing of cocks announces the dawn.

Your task is now for the nymphs, by command of Demeter,

And leaping down on the top of the wheel, they turn it,

Axle and whirling spokes together revolving and causing The heavy and hollow Nisyrian stones to grind above.

So shall we taste the joys of the golden age

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And feast on Demeter’s gift without ransom of labour.”-”

Some see in this sentence the proof that the mill to which the text refers (the one at Mithridatus? Another mill?) has a vertical axis and horizontal wheel (the Nymphs turn the axle in bounding to the top of the wheel). But this would appear to be thin proof at best. It is only under the Roman Empire, and in particular during the 1st and 2nd cen – [192] [193] [194] [195] turies AD, that the use of the water mill spreads into the Roman provinces of Asia and the West. We will return to this in more detail in Chapter 6. Note that in China we find hydraulic energy applied to complex industrial uses as early as the 1st century AD, (Chapter 8).

A constant preoccupation of the Lagide kings, pressured by their politics of prestige and expansion, was to increase agricultural productivity. Each region (or nome) is under the responsibility of an economist (the Greek name is Oikonomos), charged, among many other tasks, to “control the delivery canals across the fields, from which the peasants draw water conveyed to their cultivated fields; to verify that the feeder canals have the prescribed depth, and that their interior space is sufficient.”[183] Every retention basin has its irrigation controller (catasporeos) responsible for water distribution.

Under Ptolemy II, the region of Fayoum, already made productive during the era of the pharaohs, is brought under a new development policy. In Chapter 3, we have dis­cussed the legendary Lake Moeris, and the works realized since the time of the pharaohs (Figures 3.6 and 5.11). The capital of the region, the ancient Shedet of the Egyptians that the Greeks called Crocodilopolis,[184] is renamed Arisone, again in honor of the queen. The ancient hydraulic systems are renovated, new projects undertaken, and the lake level lowered. A chief engineer named Cleon is charged with management of the new developments of Fayoum.

Thus, when the minister of the Treasury, Apollonius,[185] [186] receives from the king Ptolemy II Philadelph a concession for the development of a vast domain of 2,700 hectares in Fayoum, he relies on the services of Cleon to establish the economic plan­ning and the layout of the hydraulic infrastructure (Figure 5.12). The correspondence of a certain Zenon of Caunos, who is successively secretary for Apollonius then manager of this domain, gives us a vivid illustration of certain aspects of water resource manage­ment in the region. In 258 BC Apollonius has the upper zone of the basin, to the north­east, developed as the “domain of ten thousand aroures”. A new city called Philadelphia is founded nearby. Certain conflicts of interest were inevitable between Cleon the engi­neer and Zenon the exploiter, as evidenced in the correspondence of Zenon:

“Zenon to Cleon, greetings! The water in the canal has not risen more than a cubit, so the

land cannot be watered from it. Therefore you would be well advised to open the gates to water the land. Stay well! (October 258 BC)

“Panakestor to Cleon, greetings! We sent you a letter on the 19th, asking you to provide us with a team to do maintenance on the bends of the small canal. Well, it seems that you have left us aside in going toward the Small Lake. Instead of avoiding us as you have done, your duty was to meet with us briefly, and having seen for yourself that the land is not being watered, to ask yourself why. Your job is not only to direct the infrastructure works in the region of the Small Lake, but also here. So, at least come meet us tomorrow at the lock and sketch out for us the path canal bends should take, for we do not have this experience. We will provide you with the labor and other facilities, whatever you command. But if you do not come, we will be obliged to write to Apollonios that his land is the only land not to be irri­gated in the region of the Lake. So, we are more than ready to make all needed facilities avail­able for you. Stay well. (October 257 BC).[187]

Is it possible that the “Small Lake” in this letter is the reservoir of Mala’a (the lake Moeris of Strabo) to the southeast of Fayoum? This seems to be the chief engineer’s main preoccupation, to the point that he neglects the domain of the minister. It is indeed thought that the works controlling this lake, the dam of Mala’a in particular, were con­structed at about this time.[188] The “domain of 10,000 aroures”, to the northeast, is irri­gated by a derivation from the Joseph canal (or Bahr Youssouf), the derivation works quite probably located near the Labyrinth. This domain includes parcels that are locat­ed on higher ground compared to the other cultivated land of the region. The lower lands must be irrigated first, which causes friction with the villagers outside the domain who think that their water has been confiscated:

“Psenemous to Zenon, greetings! The outlying peasants have taken out their (mules and shovels) and opened the irrigation ditches at the ends of the ten thousand aroures. People from Philadelphia attacked them, (chasing away) the mules and breaking (the shovels). I sent Pelois, son of Pachos, to (tell you of this). But I presume that you already know of these ugly incidents. In order that this business be cleared up as soon as possible, you would do well to order that (their land) be supplied with water. [.. .][189]

Thanks to irrigation, numerous new fruits are adapted and cultivated in Fayoum: olives, pears, apricots, figs, etc. In addition, during this period an attempt is made to develop grains yielding two annual harvests: the first planted at the falling flood, in October, and the second irrigated artificially. This is the sense of a written instruction send to Zenon:

“Apollonius to Zenon, greetings! The King has ordered us to cultivate the land a second time. Therefore, as soon as you have harvested the early grain, quickly water the land by hand. In case this is not possible, install as many irrigation machines as you can, but do not leave water on the land more than five days. Then dry the land and as quickly as possible plant the three-month wheat. Write to me personally when you are ready to harvest the
grain. Go well” (December 256 BC).[190]

The “irrigation machines” of this letter are perhaps balance beams (shadufs), or per­haps the very first models of manual waterwheels that appear in the 3rd century BC.

Two centuries after these accounts, at the beginning of the Roman domination around 25 BC, Strabo sojourns in Egypt and travels up the Nile to Aswan, in the com­pany of the prefect, newly named by Augustus. Twice in his accounts he speaks of irri­gation by “machines” (always powered by men or animals) and, in particular, the use of

Figure 5.12 Plans for development of the “domain of 10,000 aurores” and reproduction of a descriptive sketch (Orrieux, 1983; Burkhalter, 1992)

Archimedes Screws and wheels; first in the region of Memphis, then in the region of Aswan.

“There is a ridge extending from the encampment (the cantonment of a Roman legion) even as far as the Nile, on which the water is conducted up from the river by wheels and screws; and one hundred and fifty prisoners are employed in the work; and from here one can clear­ly see the pyramids.. ,.[191]

“The Nile has very many islands scattered along its course, of which some are wholly cov-

ered at its risings and others only partly; but the exceedingly high parts of the latter are irri – 30

gated by means of screws.”

In Chapter 3, devoted to Egypt of the pharaohs, we mentioned several projects that rep­resented completion or termination of efforts that the Ptolemites had begun earlier. In their development of commerce with distant partners in Arabia, and even as far as India according to Strabo, the Ptolemites needed to develop the infrastructure to access the Red Sea and to launch a fleet for this purpose. Necho’s canal, linking the pelusiac branch of the Nile with the Gulf of Suez, passing through Lake Timsah and the Bitter Lakes, is maintained or brought back into service. As we have seen in Chapter 3, a device (a single gate?) making it possible to accommodate water-level changes in the Gulf of Suez is installed. A new city, Arisone,[181] named for the sister-spouse of Ptolemy II Philadelph, is founded at the outlet of the canal. A new port on the Red Sea is con­structed at about the latitude of Aswan, 320 km southeast of the ancient Egyptian port of Gawasis;[182] this port, called Berenice after the name of the mother of Ptolemy II, is con­nected by a trail to the region of Edfou.

Lysimachus, who had received Thrace in the partition of Alexander the Great’s empire, imprudently left part of his war spoils in the custody of Philetairos, in the Asia Minor citadel of Pergamon. This citadel occupied a rocky spire that overlooked the plain from 300 m above it, and about 30 km from the sea. After the secession of Philetairos, in 282 BC, Pergamon rapidly became the capital of a kingdom, then an intellectual center that sought to rival Alexandria with a great Library (some 200,000 rolls of papyrus) and a School of original thought.

The provision of a supply of water to these citadels perched on hills always posed a problem in Antiquity. Initially, cisterns were built to store rainwater. Later, tunnels (or sinnors) were often dug to ensure access, especially during sieges, to underground cis­terns fed by springs located on the flanks of the hills; this was the solution adopted at Mycenae, and at Jersusalem.

Having become a powerful city, Pergamon needed water, and this need was met with an unprecedented hydraulic installation. The project was founded on the understanding of the hydraulic concept of a siphon and the experience of the first Hellenistic applica­tions, as well as on the mastery of the metallurgy of lead. This project is known to us through site studies carried out by a German team between 1968 and 1972.[178] Its con­struction was probably carried out during the reign of King Eumene II (197 – 159 BC). This water delivery system comprises two parts (Figure 5.8). The upstream portion brings water from the Mandradag spring (captured at an altitude of 1,230 m) as well as from other springs, some as far away as 25 km as the crow flies, to a reservoir located 3 km from the city across from the citadel, at an altitude of 376 m (i. e. about 26 m higher
than the citadel). This original project includes parallel buried pipelines (three of them downstream of the Kemerdere spring) assembled from about 200,000 connected clay sections (Figure 5.9). These sections are from 50 to 70 cm long, with interior diameters from 16 to 19 cm, and wall thicknesses of about 4 cm. The watertight joints between the sections are built up from a mixture of sand, mud, and clay, including certain organic matter such as petroleum or greases.[179] The parallel pipelines follow the slope of the land along a total length of more than 40 km. They do not flow under pressure, and thus in principle belong to the family of water delivery systems developed earlier in Greece (see the end of Chapter 4) – but on a larger scale.

Figure 5.9 The three clay pipelines of the Mandradag aqueduct (photo of G. Garbrecht).

It is the second section of the pipeline that, although much shorter, is of revolution­ary conception (Figure 5.10). It conveys water from the reservoir that we just described, at an altitude of 376 m, down to the citadel at 350 m, in a straight-line distance of only 3 km. But this section crosses a valley whose lowest elevation is only 175 m, i. e. near­ly 200 m below the reservoir. The inverse siphon comprises a pressure conduit made of lead, with an outside diameter that appears to have been 30 cm, the inside diameter
appearing to be the order of 20 cm.[180] The conduit is not buried, but rests on above­ground stone supports. No visible traces remain of the forced main itself (the metal, hav­ing considerable value, was ultimately recovered for other uses). But the conduit’s sup­port blocks, with their 30-cm holes, have been recovered, along with massive anchor blocks on the two high points of the profile, to withstand static and hydrodynamic forces. Traces of lead have been found on the ground along the course of the conduit. The lon­gitudinal profile of the pipeline (Figure 5.10) is in the form of a W, unlike the earlier U- shaped Hellenistic siphons. It seems that the designers of the facility, concerned with the effects of hydrostatic pressure corresponding to 200 m of elevation difference, sought to limit the length of pipe sections subject to the greatest pressure. They appeared to have done so by intentionally routing the conduit over intermediate high points within the depression. At these intermediate high points, there is a risk of the formation of air pock­ets that can endanger a pipe system in several respects. Air release vents were very like­ly installed at these locations.

The discharge in this system has been estimated to be 45 l/s (i. e. nearly 3,900 m3 per day). Later, urbanization spreads to the low areas situated at the foot of the hill. New aqueducts will be built, in particular during the period of Roman domination, to supply these low areas. But none of these aqueducts can rival the audacity of the Mandradag pipeline, the only one to provide water to the summit of the Acropolis. No subsequent Roman aqueduct will ever approach the bold technical audacity of this forced main.

As we have shown, Lagide Egypt undergoes a period of troubles and reduced prosperi­ty from the 2nd century, a situation not at all propitious for development. Ptolemy VIII (called Physcon – i. e. the vain) hunts down the Alexandrian intellectuals in 145 BC and later sends his mercenaries to attack this city that had revolted. Far from being lost, the discoveries of the 3rd century BC reappear in the hydraulic projects that we are going to describe subsequently. They comprise a patrimony shared by the Roman engineers and the scientists of the school of Alexandria from the first centuries of our era – the school poised for another fruitful period under Roman domination.

The implementation of new hydraulic technologies in the Hellenistic kingdoms, from the 3rd to 1st century BC

Even though Pergamon and Alexandria dominated intellectual life, the thread of innova­tion runs throughout the entire Hellenistic world in this period, from Egypt to the Black Sea. The first examples that we will describe are linked to the intensive urbanization that developed in Asia Minor. These are new cities in a mountainous country, and they demand new principles of water supply.

Hellenistic water delivery and the generalization of the siphon

As we have seen in Chapter 4, the Greek aqueducts most often use clay pipes that fol­low the slope of the terrain, as would a free-surface canal. During the Hellenistic peri­od, in the new cities of Asia Minor and Palestine, the technology of inverse siphons is developed to permit an aqueduct to cross a valley and return to a higher elevation. These siphons are schematically in the form of a “U” with depth of from 15 to 75 m (i. e. from the top to the bottom of the “U”.) The portion of the conduit that is under pressure (a “forced main”) is most often constructed from massive stone. Numerous pipe sections of this type have been recovered, often of cubical external shape, and fitted with ferrules so that individual elements can be connected to form a conduit (Figure 5.7). Often the upper portions of these elements have holes in them, probably serving as air vents, clean­ing holes, or perhaps pressure-surge relief valves.

Inverse-siphon technology made it possible for Hellenistic water-delivery systems to cross valleys without the engineering structures (bridge-aqueducts) that the Romans later used for such crossings. Their development coincides with an improved knowledge of the effects of fluid pressure, as we have seen in the previous section. But it is diffi­cult to say if this knowledge resulted from the technological development, or vice-versa. Table 5.1 summarizes some of the Hellenistic inverse siphons.

Archimedes (287 – 212 BC) was born at Syracuse, in Sicily. In all probability, he spent time in Alexandria where he studied geometry with the followers of Euclid. Though Archimedes belonged to the mathematical School, it would have been quite natural and possible for him to see the inventions of Ctesibios during his stay. Upon his return to Syracuse, he continued to correspond with the scholars of Alexandria, in particular with the mathematician Conon of Samos, and with the director of the Library, Eratosthene.11 This justifies the association of Archimedes’ work with the school of Alexandria.

First and foremost a mathematician, Archimedes was interested in the problem of buoyancy of bodies of arbitrary shape. Extreme rigor distinguishes his work – he first proposes axioms, then demonstrates their consequences. The initial postulate of his work on “floating bodies” introduces the notion of pressure:

“We take as a principle that liquid is of such a nature that, its parts being arranged in an equal and contiguous manner, the part that is the least compressed is displaced from its position by

a more compressed part, and that each of these parts is compressed by the liquid above it,

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unless the liquid is in a closed receptacle and is compressed by something else.”

As early as on the second page of his treatise, he reaches a remarkable conclusion – the surface of water at rest is not horizontal, but spherical:

“The surface of any liquid at rest will have the form of a sphere having the same center as that of the earth.”[174] [175] [176]

Later on, the pragmatic Roman engineers were perplexed by this proposition: was it

then not possible to rely on a water surface to represent a horizontal plane?[177]

Further on in this same treatise, laid out with the same rigor, are the various propo­sitions that comprise the theory of floating bodies and the well-known formulation of Archimedes’ Principle:

“Solid objects which have (for the same volume) the same weight as the liquid in which they are immersed, when released remain submerged in such a way as not to rise to the surface of the liquid or descend further down within it.

“Any solid object lighter than a liquid (for the same volume), released in this liquid, will be submerged to a level such that the liquid which occupies the volume of the submerged por­tion has the same weight as the entire solid body.

“Solid bodies lighter than a liquid (for the same volume), plunged into the liquid by force, are pushed upwards by a force equal to the excess of the weight of the body over the weight of the liquid which occupies the same volume as the solid body.

“Bodies heavier than a liquid (for the same volume), released in the liquid, descend toward the bottom until reaching it, and they are lightened in the liquid by the weight of the liquid contained in a volume equal to that of the solid body.

“If a body lighter than a liquid (for the same volume) is released in the liquid, the ratio of its weight to the weight of the same volume of liquid will be equal to the ratio of the submerged part to the total.”

In his treatise, Archimedes then determines the equilibrium of diverse solids in the form of spheres, hyperboloids of revolution, etc.

The writings of our 3rd century BC authors have unfortunately been lost for the most part. We know them primarily through citations and references contained in the writings of the subsequent period, in particular those of the Roman Vitruvius (about 25 BC) and of Heron of Alexandria (around 60 BC). It is thought that Straton of Lampasaque con­ducted the first studies of a vacuum and may be at the origin of the concept reported by Heron that “an absolute vacuum does not exist, but one can artificially produce vacuum in opposition to nature.” Straton was the private tutor of the future Ptolemy II Philadelph in about 290 BC, and, after 286 BC, he was the successor of Theophraste as the head of the Academy of Athens. One of the experiments reported by Heron, but very likely inspired by Straton, consisted in blowing air into a hermetically sealed metallic sphere through a small tube: “This shows clearly that the compression of bodies contained in the sphere enables them to reside in the dispersed pockets of the vacuum.” Inversely, one can suck out the air contained in the sphere through the same tube, “a considerable quantity can be withdrawn, without any substance taking its place inside the sphere.”[172] [173] Vitruvius credits Ctesibios of Alexandria with the invention of the “fire pump” (Figure 5.5). This would appear to be the first hydrodynamic device in which the flow of water is not driven by gravity, but by the action of an artificially induced pressure. Philon of Byzantium appears to have pursued this interest in flow devices “under pres­sure” through his interest in connected vases and siphons, and perhaps also under the influence of the work of Archimedes that we will now discuss.

Is it to increase their prestige that the first Ptolemites set themselves up as protectors of the sciences, techniques and arts? Ptolemy I created the Library of Alexandria – more of a personal collection than a true institution. The Library is then completed by the Museum, either by Ptolemy I himself, or by his successor Ptolemy II Philadelph, who reigned from 285 to 246 BC. The Library is dedicated to the acquisition[166] and conserva­tion of books, whereas the Museum was what one would call today a research institute. The director of the Library and the members of the Museum are supported by the Ptolemites and in general, the financing of the two institutions is entirely assured by the state. It is believed that the Museum and the royal Library – the latter thought to have contained 500,000 rolls of papyrus[167] – were housed in the same building, in the interior of the royal palace grounds. A library annex, open to the public, was set up outside the palace grounds in a temple called the Serapeum.

Scholars from the entire Hellenistic world flocked to Alexandria, either to live there, or to study or make extended stays. This is why one can confidently use the term school

of Alexandria to describe the vast intellectual movement associated with it.

First there was mathematics. The foundations had been laid by the Greeks during the classical period, and the easterners, Babylonians and Egyptians, were equally known for their mastery of geometry. In about 300 BC Euclid set forth the foundations of our modern geometry, and through his students the mathematical school of Alexandria becomes a reference for Antiquity. Geometry underpins and enables many lines of thought and activity; we will see this later in the context of Archimedes of Syracuse. Geometry enabled Eratosthene of Cyrene, director of the Library during the era of Ptolemy III Evergete (who reigned from 246 to 221 BC), to determine the circumference of the earth with remarkable precision.[168] Eratosthene deduced this circumference from measurement of the height of the sun at noon at Alexandria when the sun is at its zenith at Syene (Aswan) – a city which is near the Tropic of Cancer – taking into account the measured distance between Alexandria and Aswan.

The new element here, compared to Greek science, is that the applied sciences are for the honor of Alexandria, even if their function is often only to “please our senses in charming our eyes and ears.”[169] Ctesibios of Alexandria (around 270 BC) and Philon of Byzantium (around 200 BC) invented “marvelous machines” – water clocks, pumps, automata, diverse mechanical devices. The invention of the hydraulic organ is credited to Ctesibios. The invention of the hydraulic screw (called cochlea (snail) by greco – roman historians, with reference to the snail’s spiral shell) as a mechanism for lifting water, is attributed by ancient authors to Archimedes at the time of his sojourn at Alexandria. During the Hellenistic period it is these Archimedes screws (Figure 5.3) which make it possible to create the famous hanging gardens of Babylon.[170] Other lift­ing devices, always muscle-powered,[171] appear during this period: the waterwheel and the bucket chain, or saqqya (Figure 5.4). Strabo, at the beginning of the roman occupation, notes the use of the lifting waterwheel in Egypt, a device that will be widespread in Asia during the roman period.

Setting out from Macedonia, with contingents of Macedonian and Greek soldiers, Alexander achieved a first victory over the Achaemenid King Darius II, who ruled the Persian Empire, at the battle of Issus. Egypt falls without resistance into the clutches of Alexander, who makes a long sojourn there from 332-331 BC. During this sojourn, he founds Alexandria on the seafront, an ideal site for the development of commerce, lying [163] between the sea and a lagoon. But the site is poorly supplied with fresh water, being some distance from the Nile. Considerable engineering efforts are undertaken to support the burgeoning activity of the city (Figure 5.2). These include a kilometer-long dike (hepstastade) to link the island of Pharos to the coast, a 30-km canal to bring fresh water from the Nile, and numerous cisterns to store this water. Later a lighthouse is built to guide maritime navigators along this low-lying and dangerous coast. [164]

Leaving Alexandria, the conqueror succeeds in completely destroying the Persian Empire through a decisive victory, and pushes on to the Indus. He dies an early death at Babylon in 323 BC, before having solidified his Empire. Indeed, his generals divide up – and fight over – the elements of that Empire. The Macedonian Ptolemy, son of Lagos, founds the dynasty of the Lagides in Egypt. Lysimachus receives Thrace. Seleucos obtains Babylonia several years later, and then Syria. But his family line, the Seleucids, only intermittently govern lower Mesopotamia, as it is fought over by other powers such as the Parthes, who progressively push the Seleucids toward Syria. New kingdoms of Hellinistic culture appear to the north of the empire of the Seleucids, along the Black Sea: Pontus, Bithynia, and Cappadocia. The power of the city of Pergamon, initially just a simple fortress, increases in Asia Minor and it becomes a dependency of the Seleucids from about 282 to 260 BC, capital of an increasingly powerful empire. From 260 BC, the influence of Pergamon becomes comparable to that of Alexandria.

The Seleucids are conquered by the Romans, allied with Pergamon, in 189 BC. In 133 BC the last king of Pergamon bequeaths his kingdom to Rome. From the middle of the 2nd century BC, a certain decadence of the Lagide Dynasty sets in, including eco­nomic difficulties and revolts. With the death of Cleopatra, in 31 BC, Egypt in its turn falls under the control of the Roman Empire.

In 335 – 331 BC, Alexander the Great conquered the totality of Greece and the Persian Empire, including Egypt and Mesopotamia. The spirits of analysis and hydraulic know­how now were brought together in the same crucible, fueled by the need to innovate – in order to ensure survival in a world whose boundaries were suddenly pushed enlarged, and to increase agricultural productivity to meet the needs of the new ruling classes. This crucible has a name: Alexandria.