Eupalinian aqueduct
Encyclopedia
Samos Island
Samos is a Greek island in the eastern Aegean Sea, south of Chios, north of Patmos and the Dodecanese, and off the coast of Asia Minor, from which it is separated by the -wide Mycale Strait. It is also a separate regional unit of the North Aegean region, and the only municipality of the regional...
, Greece
Greece
Greece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....
, built in the 6th century BC to serve as an aqueduct
Aqueduct
An aqueduct is a water supply or navigable channel constructed to convey water. In modern engineering, the term is used for any system of pipes, ditches, canals, tunnels, and other structures used for this purpose....
. The tunnel is the second known tunnel in history which was excavated from both ends , and the first with a geometry-based approach in doing so. Today it is a popular tourist attraction.
Historical data
Tyrant
A tyrant was originally one who illegally seized and controlled a governmental power in a polis. Tyrants were a group of individuals who took over many Greek poleis during the uprising of the middle classes in the sixth and seventh centuries BC, ousting the aristocratic governments.Plato and...
Polycrates
Polycrates
Polycrates , son of Aeaces, was the tyrant of Samos from c. 538 BC to 522 BC.He took power during a festival of Hera with his brothers Pantagnotus and Syloson, but soon had Pantagnotus killed and exiled Syloson to take full control for himself. He then allied with Amasis II, pharaoh of Egypt, as...
.
During his reign, two groups working under the direction of the engineer Eupalinos
Eupalinos
Eupalinos or Eupalinus of Megara was an ancient Greek engineer who built the Tunnel of Eupalinos on Samos Island in the 6th century BC....
from Megara
Megara
Megara is an ancient city in Attica, Greece. It lies in the northern section of the Isthmus of Corinth opposite the island of Salamis, which belonged to Megara in archaic times, before being taken by Athens. Megara was one of the four districts of Attica, embodied in the four mythic sons of King...
dug a tunnel through Mount Kastro to build an aqueduct
Aqueduct
An aqueduct is a water supply or navigable channel constructed to convey water. In modern engineering, the term is used for any system of pipes, ditches, canals, tunnels, and other structures used for this purpose....
to supply the ancient capital of Samos (today called Pythagoreion
Pythagoreion
The remains of the Pythagoreion, an ancient fortified port with Greek and Roman monuments and a spectacular tunnel, the Tunnel of Eupalinos or Eupalinian aqueduct, along with the Heraion of Samos were jointly registered as a UNESCO World Heritage Site in 1992....
) with fresh water. This was of utmost defensive importance, as the aqueduct ran underground it was not easily found by an enemy who could otherwise cut off the water supply.
The Eupalinian aqueduct was used for a thousand years, as proved from archaeological findings. It was rediscovered in 1882-1884 and today is open to visitors.
The text of Herodotus
The Eupalinian aqueduct or ditch, is cited by HerodotusHerodotus
Herodotus was an ancient Greek historian who was born in Halicarnassus, Caria and lived in the 5th century BC . He has been called the "Father of History", and was the first historian known to collect his materials systematically, test their accuracy to a certain extent and arrange them in a...
(Histories 3.60), without whom it would not have been discovered:
- And about the Samians I have spoken at greater length, because they have three works which are greater than any others that have been made by Hellenes: first a passage beginning from below and open at both ends, dug through a mountain not less than a hundred and fifty orguiaFathomA fathom is a unit of length in the imperial and the U.S. customary systems, used especially for measuring the depth of water.There are 2 yards in an imperial or U.S. fathom...
in height; the length of the passage is seven stadia and the height and breadth each eight feet, and throughout the whole of it another passage has been dug twenty cubits in depth and three feet in breadth, through which the water is conducted and comes by the pipes to the city, brought from an abundant spring: and the designer of this work was a Megarian, Eupalinos the son of Naustrophos. This is one of the three; …
Description
The tunnel took water from an inland springSpring (hydrosphere)
A spring—also known as a rising or resurgence—is a component of the hydrosphere. Specifically, it is any natural situation where water flows to the surface of the earth from underground...
, which was roofed over and thus concealed from enemies. A buried channel, with periodic inspection shafts, winds along the hillside to the northern tunnel mouth. A similar hidden channel, buried just below the surface of the ground, leads from the southern exit eastwards to the town of Pythagoreion.
In the mountain itself, the water used to flow in pipes in a separate channel several metres below the human access channel, connected to it by shafts or by a trench.
The southern half of the tunnel was dug to a larger dimensions than the northern half, which in places is only just wide enough for one person to squeeze through, and has a pointed roof of stone slabs to prevent rockfalls. The southern half, by contrast, benefits from being dug through a stabler rock stratum.
The two headings meet at a dogs-leg
Dogleg
Dogleg or dog-leg may refer to:Motor vehicles*Dog leg, an unusual manual transmission layout*Dog-leg, an offset 'zig-zag' plane of operation for a floor-mounted automatic transmission shift lever* The area behind the rear door on a four door car...
, a technique which was used to avoid the two tunnels missing each other, as explained in the paragraph "Surveying techniques".
Surveying techniques
The method Eupalinos employed to make the two groups meet in the middle of the mountain, is documented by Hermann J. Kienast and other researchers. In planning the digging, Eupalinos used what are now well-known principles of geometryGeometry
Geometry arose as the field of knowledge dealing with spatial relationships. Geometry was one of the two fields of pre-modern mathematics, the other being the study of numbers ....
, which were codified by Euclid
Euclid
Euclid , fl. 300 BC, also known as Euclid of Alexandria, was a Greek mathematician, often referred to as the "Father of Geometry". He was active in Alexandria during the reign of Ptolemy I...
several centuries later. With a length of 1,036 metres, the Eupalinian subterranean aqueduct is famous today as one of the masterpieces of ancient engineering.
Eupalinos was aware that mistakes in measurement could make him miss the meeting point of the two teams, either horizontally or vertically. He therefore employed the following techniques:
In the horizontal plane
Since two parallel lines never meet, Eupalinos recognized that a mistake of more than two metres horizontally (approximate cross section was 1.8 by 1.8 m), would make him miss the meeting point. Having calculated the expected position of the meeting point, he changed the direction of both tunnels, as shown in the picture (one to the left and the other to the right), so that a crossing point would be guaranteed, even if the tunnels were previously parallel and far away.In the vertical plane
Similarly, there was a possibility of deviations in the vertical sense, even though his measurements were quite accurate; Kienast reports a vertical difference in the opening of the tunnels of only four centimetres. However, Eupalinos could not take a chance. He increased the possibility of the two tunnels meeting each other, by increasing the height of both tunnels. In the north tunnel he kept the floor horizontal and increased the height of the roof, while in the south tunnel, he kept the roof horizontal and increased the height by changing the level of the floor. His precautions in the vertical sense proved unnecessary, since measurements show that there was practically no mistake.Literature
- The Aqueduct of Eupalinos on Samos, Hermann J Kienast, Ministry of Culture Archaeological Receipts Fund, Athens, 2005. ISBN 960-214-424-6, 60 pp, €9-80