Tunnel of Eupalinos – Wikipedia

The Tunnel of Eupalinos or Eupalinian aqueduct (Greek: Ευπαλίνιον όρυγμα, romanized: Efpalinion orygma) is a tunnel of 1,036 m (3,399 ft) size working by Mount Kastro in Samos, Greece, constructed within the sixth century BC to function an aqueduct.^[1] The tunnel is the second recognized tunnel in historical past which was excavated from each ends (Ancient Greek: ἀμφίστομον, romanized: amphistomon, “having two openings”), and the primary with a geometry-based method in doing so.^[2] Immediately it’s a standard vacationer attraction. The tunnel is inscribed on the UNESCO World Heritage List together with the close by Pythagoreion and Heraion of Samos, and it was designated as an International Historic Civil Engineering Landmark in 2017.^[3][4]

Early historical past[edit]

The Eupalinian aqueduct is described by Herodotus (Histories 3.60), with out whom it may not have been found:

I’ve dwelt longer upon the historical past of the Samians than I ought to in any other case have achieved, as a result of they’re answerable for three of the best constructing and engineering feats within the Greek world: the primary is a tunnel practically a mile lengthy, eight toes vast and eight toes excessive, pushed clear by the bottom of a hill 9 hundred toes in top. The entire size of it carries a second slicing thirty toes deep and three broad, alongside which water from an plentiful supply is led by pipes into the city. This was the work of a Megarian named Eupalinus, son of Naustrophus.^[5]

The tunnel may also be referred to within the Homeric Hymn to Apollo, which mentions “watered Samos.”^[6] The tunnel was dug within the mid-sixth century BC, by two teams working underneath the path of the engineer Eupalinos from Megara, with a view to provide the traditional capital of Samos (at this time known as Pythagoreion) with recent water. This was essential for demographic causes: the town of Samos had outgrown the capability of the wells and cisterns throughout the metropolis’s limits, however the principle supply of recent water on the island was on the opposite facet of Mount Kastro from the town. It was of the utmost defensive significance; as a result of the aqueduct ran underground, it couldn’t simply be discovered by an enemy, who would possibly in any other case minimize off the water provide. The date of building isn’t totally clear. Herodotus mentions the tunnel within the context of his account of the tyrant Polycrates, who dominated c. 540–522 BC, however he doesn’t explicitly say that Polycrates was answerable for its building. Aideen Carty means that it needs to be related with the regime that overthrew the Geomori within the early sixth century BC, which granted citizenship to numerous Megarians, maybe together with Eupalinos.^[7] The Eupalinian aqueduct was used as an aqueduct for 1100 years, earlier than it started to silt up. Within the seventh century AD, the south finish was used as a defensive refuge.^[8]

Description[edit]

Spring and reservoir[edit]

The tunnel took water from an inland spring, situated about 52 metres (171 ft) above sea degree close to the fashionable village of Ayiades. It discharges about 400 m³ of water per day. This spring was coated over. Two rectangular openings, every measuring 28 by 26 centimetres (11 by 10 in), feed the water into a big reservoir with a roughly elliptical floor plan. Fifteen massive stone pillars help a roof of large stone slabs. The spring was thus fully hid from enemies. The development of this reservoir appears to have brought on the outlet of the spring to subside by a number of metres. Sooner or later earlier than the nineteenth century, a church devoted to St John was constructed excessive of this reservoir, additional hiding the spring’s location.^[9]

North channel[edit]

From the spring, a buried channel winds alongside the hillside to the northern tunnel mouth. The channel is 890 metres (2,920 ft) lengthy, though the gap from the spring to the tunnel mouth because the crow flies is barely 370 metres (1,210 ft). The channel is 60–70 centimetres (24–28 in) vast and about 5 metres (16 ft) deep. After it had been minimize out of the bedrock, it was coated over with stone slabs after which buried. There are inspection shafts at common intervals alongside the channel’s course. The final 150 metres (490 ft) of this channel cross underneath a small hill. Vertical shafts had been dug from the floor at intervals of 30–50 metres (98–164 ft) after which linked as much as create a brief tunnel, which brings the water.^[10]

Tunnel of Eupalinos[edit]

Strengthened part of the tunnel, with pointed roof and polygonal masonry partitions.

The tunnel by Mount Kastro carried the water for a distance of 1,036 metres (3,399 ft). The tunnel is mostly 1.8 by 1.8 metres (5.9 by 5.9 ft). The southern half of the tunnel was dug to bigger dimensions than the northern half, which in locations is simply vast sufficient for one individual to squeeze by. The southern half, against this, advantages from being dug by a extra secure rock stratum.^[11] In three sections, a pointed roof of stone slabs was put in to forestall rockfalls. Two of those sections, protecting 153 metres (502 ft), are close to the north finish of the tunnel; the third part is 12 metres (39 ft) m on the southern finish of the tunnel. The partitions of the tunnel had been additionally confronted with masonry in these sections, utilizing polygonal masonry on the south finish and huge slabs on the northern finish. Within the Roman Imperial period, barrel vaults had been constructed with small stones and plaster to bolster different sections of the tunnel.^[12]

The width of the tunnel signifies that there would have been house for under two diggers to work at a time. To hurry up the method, the tunnel was dug from each ends concurrently. H. J. Kienast calculates that such employees would have been capable of dig out 12–15 centimetres (4.7–5.9 in) of stone per day, that means that all the tunnel took not less than eight years to dig.^[11]

Cross-section of the tunnel (1), with the water channel containing the precise water-pipe (2), and a vertical shaft linking the 2 (3).

The ground of the tunnel is sort of horizontal and roughly 3 metres (9.8 ft) above the extent of the water at its supply. Apparently, the subsidence on the spring lowered the extent of the water after work had begun, leaving the tunnel too excessive. A separate channel needed to be dug beneath the east half of the tunnel to hold the water itself. It will increase in depth over the course of the tunnel, from 4 metres (13 ft) m deep on the north finish to eight.5 metres (28 ft) on the southern finish. Vertical shafts hyperlink this channel to the principle tunnel roughly each ten metres. These had been dug from the tunnel after which linked collectively to create the channel; as soon as building was completed, they served as inspection shafts. Particles from this channel was merely dumped in the principle tunnel.^[13]

A lot of symbols and letters painted on the wall testify to a variety of measurements. Three of them (Κ, Ε, and ΚΒ on the east wall), clearly mark the factors the place vertical shafts had been minimize. On the west wall, there are letters in alphabetical order at a daily interval of 20.59 metres (67.6 ft), which point out that this was the essential unit of measurement utilized by Eupalinos (it’s one fiftieth of the deliberate course by the mountain). The meanings of the opposite symbols haven’t but been decided.^[14]

Throughout the channel, the water was transported in a pipe produced from terracotta sections, which had been 72 centimetres (28 in) lengthy and 26 centimetres (10 in) in diameter. The total pipe should have required round 5,000 of those sections. They had been joined to 1 one other with lime mortar. The highest quarter of the pipes was minimize open to permit sediment and different detritus to be eliminated, in order that the aqueduct didn’t silt up. A break within the pipe close to the north entrance of tunnel led to massive quantities of mud getting into the pipe, which needed to be cleared out commonly.^[15]

Within the seventh century AD, when the aqueduct had ceased to function, the southern part of the tunnel was transformed to function refuge. This included the development of a cistern 400 metres (1,300 ft) from the southern entrance to gather water dripping from a vein within the rock.^[16]

Southern channel[edit]

Shortly earlier than the southern mouth of the tunnel, the water channel diverges from the principle tunnel and heads by the rock in a hidden channel like that to the north of the tunnel, which is buried just under the floor of the bottom. It carries the water eastwards to the city of Pythagoreion. Solely about 500 metres (1,600 ft) of this channel have been excavated, however its complete size should have been round 1,000 metres (3,300 ft). Two monumental fountains on the hillside inside the town appear to be on the road of this channel. They contained a reservoir and basins from which individuals might acquire the water and carry it to their houses.^[17]

Surveying strategies and building[edit]

As a way to align the 2 tunnels, Eupalinos first constructed a “mountain line”, working excessive of the mountain on the best a part of the summit despite the fact that this gave a non-optimal place each for feeding water into the tunnel and for water supply to the town. He related a “south line” to the mountain line on the south facet going straight into the mountain, which fashioned the south tunnel. On the north facet a “north line” is related to the mountain line, guiding the minimize into the mountain from the north facet.^[18] As the employees dug, they checked that their course remained straight by making sightings again in the direction of the doorway of the tunnel. That is proven by some extent within the southern half of the tunnel the place the course by chance diverged to the west and needed to be corrected; a notch has been minimize out of the rock on the within of the curve, with a view to restore the sight line.^[19]

After 273 metres (896 ft) from the northern finish, an space filled with water, weak rock and dirt pressured Eupalinos to change his plan and direct the tunnel to the west. When leaving the road Eupalinos deliberate his diversion as an isosceles triangle, with angles 22.5, 45, and 22.5 levels. Measuring errors occurred and Eupalinos barely overshot. When this was realised, the north tunnel was redirected to the east as soon as extra. The slicing of the south tunnel was fully straight, however stopped after 390 metres (1,280 ft).^[18][20]

Eupalinos used a unit of 20.59 metres (67.6 ft) for distance measurements and a unit of seven.5 levels (1/12 of a proper angle) for setting out instructions.^[18][21]

See Also

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Assembly level[edit]

The north and south halves of the tunnel meet in the midst of the mountain at a dog-leg, a method to guarantee they didn’t miss one another (This methodology is documented by Hermann J. Kienast and different researchers). In planning the dig, Eupalinos used now well-known ideas of geometry, codified by Euclid a number of centuries later. With a size of 1,036 metres (3,399 ft), the Eupalinian subterranean aqueduct is legendary at this time as one of many masterpieces of historical engineering. When the 2 tunnels attain inside earshot, which could be estimated for such a rock to approximate 12 metres (39 ft), the tunnels may very well be directed in the direction of one another, however a excessive degree of accuracy was required to achieve that time. Errors in measurement and staking might trigger Eupalinos to overlook the assembly level of the 2 groups, both horizontally or vertically. He due to this fact employed the next strategies.

Within the horizontal airplane[edit]

Eupalinos calculated the anticipated place of the assembly level within the mountain. Since two parallel traces by no means meet, an error of greater than two metres (6.6 ft) horizontally meant that the north and south tunnels would by no means meet. Due to this fact, Eupalinos modified the path of each tunnels, as proven within the image (the north tunnel to the left and the south tunnel to the best). This gave a catching width that was wider by 17 metres (56 ft), so {that a} crossing level can be assured, even when the tunnels had been beforehand parallel and much away. They thus meet at practically a proper angle.^[22]

Within the vertical airplane[edit]

At first of labor, Eupalinos levelled across the mountain most likely following a contour line with a view to make sure that each tunnels had been began on the identical altitude. The opportunity of vertical deviations within the means of excavation remained, nevertheless. He elevated the potential for the 2 tunnels assembly one another, by growing the peak of each tunnels on the level close to the be part of. Within the north tunnel he stored the ground horizontal and elevated the peak of the roof by 2.5 metres (8.2 ft), whereas within the south tunnel he stored the roof horizontal and lowered the degree of the ground by 0.6 metres (2.0 ft). His precautions as to vertical deviation proved pointless, nevertheless, since measurements present that there was little or no error. On the rendezvous, the closing error in altitude for the 2 tunnels was a couple of millimetres.^[18][23]

The signal on the finish of the a part of the Eupalinian aqueduct that’s open to the general public

Rediscovery and excavation[edit]

Students started looking for the tunnel within the nineteenth century, impressed by the reference to it in Herodotus. The French archaeologist, Victor Guérin recognized the spring that feeds the aqueduct in 1853 and the beginnings of the channel. In 1882, work started on clearing the tunnel with the aim of bringing it again into use. This proved too troublesome and the hassle was known as off, but it surely allowed Ernst Fabricius to analyze the tunnel on behalf of the German Archaeological Institute. He printed the ends in 1884 as “Die Wasserleitung des Eupalinos.”^[24] Full excavations of the tunnel had been carried out by Ulf Jantzen from 1971-1973, who lastly cleared the total size of the tunnel, which had turn into crammed with silt. A full survey of the tunnel with detailed geodetic measurements was carried out by Hermann J. Kienast.^[25] Parts of the tunnel are open to the general public.

References[edit]

Literature[edit]

• Apostol, Tom M. (2004). “The Tunnel of Samos” (PDF). Engineering and Science. 1: 30–40.
• Kienast, Hermann J. (2005). The Aqueduct of Eupalinos on Samos. Athens: Ministry of Tradition Archaeological Receipts Fund. p. 60. ISBN 960-214-424-6.
• Olson, Åke (2012). “How Eupalinos navigated his method by the mountain-An empirical method to the geometry of Eupalinos”. Anatolia Antiqua, Institut Français d’Études Anatoliennes. XX: 25–34.

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