More light in the tunnel of Eupalinos

The restoration works on the unique tunnel of Eupalinos, part of the Archaic aqueduct on Samos, and the information that the new evidence from them provides, especially on its linings, are presented in brief. New hypotheses for the design and the construction of the tunnel are also proposed. The center line of the tunnel was initially laid out over the hill surface with long scaffolding. Then, in order to ensure the accuracy of the excavation, the line was transposed inside with the help of two light signals, one on the opposite hillside to the north and one on a wooden tower near the seaside to the south. The problem of the loss of the northern signal on account of low visibility caused by the flow of water, which produced high humidity and consequently a misty atmosphere inside the tunnel, was solved by Eupalinos by the modification of driving a V-shaped deviation, by which he approached the target correctly and succeeded in making an exact breakthrough. The level of the tunnel was defined accurately in the initial design. The trench on the east side of the tunnel was also part of the initial design and was excavated simultaneously with the tunnel itself: it facilitated proper ventilation during the excavation. No more than four years were needed to finish construction.