Eupalinos

Eupalinos (Ancient Greek: Εὐπαλῖνος) or Eupalinus of Megara was an ancient Greek engineer who built the Tunnel of Eupalinos on Samos Island^: 27 in the late 6th century BC.^: 27 Though the construction of the tunnel has been attributed to the tyrant Polycrates of Samos,^: 27 it is now considered to be a later construction and having been built between 550 and 530 BC.^: 149 In any case, the tunnel was, and is, regarded as a major feat of engineering.^: 149

The tunnel 1,036 m (3,399 ft) long conveyed water from a spring near Mount Kastro through the mountain into the ancient city of Samos (modern Pythagoreio).^{: 149 : 27} It was the longest one of its time and it still exists. The tunnel was excavated from both ends,^{: 27 : 173} but it is not the first one known to be built in this manner -- a tunnel channeling water to Jerusalem was built from both ends at the same time earlier, in the 8th century BC.^: 173

The route of the tunnel does not follow a direct line -- for several hundred meters on both ends, it does follow a straight line, but in the middle third, there are several turns.^{: 29 : 150} Additionally, the tunnel has two parts: A main tunnel and a trench running along the left side of the main tunnel.^: 27 The main tunnel is 1.8 m × 1.8 m (5.9 ft × 5.9 ft) square in cross-section.^: 27 And, while the main tunnel is horizontal, the trench gets progressively deeper with an average gradient of 0.4% and gets from 3.5 to 8.5 m (11 to 28 ft) deep.^{: 28 : 150} On the bottom of the trench ran a terracotta pipeline carrying the water.^{: 27 : 149}

Eupalinos is considered the first hydraulic engineer in history whose name has been passed down. Apart from that, though, nothing more is known about him.

Efpalinos Tunnel, a road tunnel built under the Geraneia mountains in Corinthia and completed in 2017, is named after Eupalinos.