Tunnel of Eupalinos

Greek: Ευπαλινειο ορυγμα
Where: Samos island
Built: 6th Century BC
Engineer: Eupalinos from Megara

Tunnel of Eupalinos.

Tunnel of Eupalinos.

The Tunnel of Eupalinos is a tunnel of 1,036m in length built in 530 BC in Samos, Greece. It was built to serve as an aqueduct and is considered to be a masterpiece of ancient engineering.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. The tunnel was built to act as a water supply for the main port city in Samos. With the advancement of the Persian army on Samos the people of Samos needed safe access to the closest water supply and they needed it fast. Therefore, instead of building the tunnel from one direction and coming out the other they needed to built it from both sides of the mountain and have it meet in the middle.

The students of Pythagoras were entrusted with this difficult job, under the direction of the engineer Eupalinos (whom the tunnel is named after) from Megara. Eupalins needed to figure out a way to have both sides meet in the middle and did so using well-known principles of geometry. If Eupalinos made a mistake of more than two metres with his measurements it would be disastrousas the two sides would not meet in the middle and would miss each other completely. Knowing that two parallel lines never meet, and having calculated where the expected meeting point in the middle should be, he changed the position of both tunnels close to their meeting point so that a crossing point would be guaranteed. The tunnel would be used for the next thousand years only to be buried and forgotten until recently re-discovered one hundred years ago.

Today the tunnel remains as a popular tourist attraction but may never have been discovered if it weren’t for Herodotus describing it in one of his scripture:

“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 orguia 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.”

There are no other scriptures that mention the tunnel and if it were not for Herodotus description we may never have even known about it. In 1853, Using this description as his guide, the French archaeologist Victor Guerin began searching for it. He was able to locate the spring and the beginning of the aqueduct but did not discover the tunnel. For the next 30 years people continued to look for it and it wasn’t until in 1882 when a monk revealed where the tunnel was that an effort was made to re-open the tunnel and clean it out. However, due to the difficulty of cleaning the tunnel it was abandoned and it wasn’t until 90 years later in 1971 that the tunnel was finally cleaned and cleared by the German Archaeological Institute of Athens.


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