Pharos of Alexandria
When Alexander the great conquered Egypt he found a great new city on a neck of land between Lake Marcotis and the Mediterranean Sea. The city, like so many others founded by Alexander, was named after him – Alexandria; and it soon became the greatest commercial and cultural center of the Mediterranean world. Just offshore there is a small island called Pharos, which was linked to the mainland by a mole three-quarters of a mile long. Very likely the idea of building a lighthouse on Pharos island was Alexander's; but the plan was not carried out until the reign of Ptolemy of Philadelphus. The new building must have been worth its great cost (800 talents), for the coastlands around Alexandria are flat and ships coming into port need guidance. The Lighthouse, which was given the same name as the island, was completed in 279 BC. It was about 400 feet high. The uppermost of its three stories had windows facing out to sea, and the light of the fire which burned there all night could be seen from a great distance. Fuel for the fire was probably raised by a lift. References by ancient writers suggest that the light may even have been reflected and directed seaward by convex mirrors; possibly mirrors were used i the daytime to reflect rays of the sun toward incoming ships; possibly the Alexandrians had even developed a lens which was used as a telescope, so that the Pharos was a watchtower as well as a lighthouse. Whatever the truth may be, the Pharos reflected the Alexandrians' interest in the applied sciences, and from a scientific point of view this creation of the designer Sostratus of Cnidos is perhaps the most remarkable of the seven wonders.
The Pharos was destroyed by stages. The lantern fell in about 700 AD; the top story some 400 years later; and an earthquake in the 14th century reduced what remained to a mere stump. This earthquake, and that which ruined the Mausoleum, thus left the Pyramids – the oldest and most magnificent of the seven wonders – as the only survivor.
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