Tunnel of Eupalinos
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The Tunnel of Eupalinos or Eupalinian aqueduct (in Greek: Efpalinion orygma, Ευπαλίνιον όρυγμα) is a tunnel of 1,036 m length in Samos, Greece, built in the sixth century BC to serve as an aqueduct. The tunnel is the second known tunnel in history which was excavated from both ends (amfistomon, αμφίστομον, 'having two openings'), and the first with a methodical approach in doing so.[1] The Eupalinos tunnel was also the longest tunnel of its time. Today it is a popular tourist attraction.
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[edit] Historical data
In the sixth century BC, Samos was ruled by the famous tyrant Polycrates.
During his reign, two groups working under the direction of the engineer Eupalinos from Megara dug a tunnel through Mount Kastro to build an aqueduct to supply the ancient capital of Samos, (which today is called Pythagoreion), 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 1882-4 and today is open to visitors.
[edit] The text of Herodotus
The Eupalinian aqueduct or ditch, is cited by Herodotus (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 fathoms [200 m] in height; the length of the passage is seven furlongs 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;...
[edit] 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. 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:
[edit] 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.
[edit] 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! Eupalinos though, could not take a chance. He increased the possibilities 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.
[edit] References
- ^ The oldest known tunnel, at which two teams advanced simultaneously was Hezekiah's tunnel in Jerusalem, completed around 700 BC. However, numerous false starts in wrong directions, which took the tunnel 1,500 feet to cover a distance of 1,000 feet, indicate that the work was done without a methodical approach (Burns 173). Rather, the workers followed probably an underground watercourse (Apostel 33).
[edit] Literature
- Alfred Burns, “The Tunnel of Eupalinus and the Tunnel Problem of Hero of Alexandria,” Isis, Vol. 62, No. 2. (Summer, 1971), pp. 172-185
- B. L. Van der Waerden, “Eupalinos and His Tunnel,” Isis, Vol. 59, No. 1. (Spring, 1968), pp. 82-83
- Harry B. Evans, Review of Hermann Kienast, “Die Wasserleitung des Eupalinos auf Samos,” American Journal of Archaeology, Vol. 103, No. 1. (Jan., 1999), pp. 149-150
- Hermann J. Kienast: Die Wasserleitung des Eupalinos auf Samos, Deutsches Archäologisches Institut Athen (German)
- Hermann J Kienast: Die Wasserleitung des Eupalinos auf Samos (Samos XIX.), Rudolph Habelt, Bonn 1995. ISBN 3-7749-2713-8
- June Goodfield, Stephen Toulmin, “How Was the Tunnel of Eupalinus Aligned?,” Isis, Vol. 56, No. 1. (Spring, 1965), pp. 46-55
- Tom Apostel, “The Tunnel of Samos,” Engineering and Science, No.1 (2004), pp.30-40
