Slavery in the Ottoman Empire and the Barbary slave trade was fundamental to its economy. The Barbary Pirates were then raiding Europe and they took more than a million Europeans off to the slave markets of Tripoli and elsewhere. 1755 tsunami On 1 November 1755, the Lisbon earthquake caused a tsunami to strike the Cornish coast at around 14:00. At Mount's Bay the sea rose at great speed and ebbed at the same rate. Settlements There are several coastal towns and villages dotted around Mount's Bay of which the largest is Penzance. To the west are Newlyn, Paul, Mousehole and Lamorna, and to the east are Marazion, Perranuthnoe, Praa Sands, Porthleven and Mullion. The bay also incorporates many beaches, coves and features including Prussia Cove, Loe Pool (and Loe Bar), Church Cove, Poldhu Cove and Kynance Cove. In the churchyard wall of the church of St. Paul Aurelian in Paul is the 1860 monument to Dolly Pentreath, according to tradition the last native speaker of the Cornish language. Mount's Bay gives its name to Mounts Bay Academy, a secondary school in Heamoor that serves Penzance and the surrounding countryside. Industry A number of mines were established along the shore and at least three were below the high water mark. An elvan dyke, rich in tin, runs nearly parallel with the Penzance promenade, at about from the shore. According to folklore, numerous veins of nearly pure cassiterite were worked by the ″old men″ in the early 18th-century. Over three summers, from 1778 Thomas Curtis sank a shaft on the Wherrytown reef and then built a 20-foot high wooden tower with a dressed stone breakwater at the base. In 1790, £600 worth of tin was produced by ten men and in 1792, the tin was worth £3000. By 1798, £70,000 worth of the tin was sold. In this year an American ship is said to have demolished the tower and machinery, during a storm and the mine closed. An 1823 attempt at reopening failed as did another in 1836 when a 40-inch cylinder engine was erected on the shore and sold by auction, four years later in 1840. While not as rich in tin as the Wherrytown reef the Long Rock reef produced tin between 1819 and 1823. A lode containing needle antimony, copper, tin and mundic crosses the reef from east to west, and an argentiferous lead lode ran along the