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Show 438 EARTHQUAKE OF LISBON, ETC., A.D. 1755. length, opened in a neighbouring hill, and a great landslip obstructed the river Lontne for ten days, giving rise to a considerable lake. Azores, 1757.-In the year 1757, the island of St. George was struck by an earthquake, and eighteen small islets rose at the distance of about two hundred yards from the shore. These may possibly have been produced by a submarine eruption. Lisbon, 1755.-In no part of the volcanic region of southern Europe has so tremendous an earthquake occurred in modern times as that which began on the 1st of November, 1755, at Lisbon. A sound of thunder was heard under ground, and immediately afterwards a violent shock threw down the greater part of that city. In the course of about six minutes, sixty thousand persons perished. The sea first retired and laid the bar dry ; it then rolled in, rising fifty feet or more above its ordinary level. The mountains of Arrabida, Estrella, Julio, Marvan, and Cintra, being some of the largest in Portugal, were impetuously shaken, as it were, from their very foundations ; and most of them opened at their summits, which were split and rent in a wonderful manner, huge masses of them being thrown down into the subjacent valleys •'~<. Flames are related to have issued from these mountains, which are supposed to have been electric; they are also said to have smoked; but vast clouds · of dust seem to have given rise to this appearance. The most extraordinary incident which occurred at Lisbon during the catastrophe was the subsidence of a new quay, built entirely of marble, at an immense expense. A great concourse of people had collected there for safety, as a spot where they might be beyond the reach of falling ruins; but, suddenly, the quay sank down with all the people on it, and not one of the dead bodies ever floated to the surface. A great number of boats and small vessels anchored near it, all full of people, were swallowed up, as in a whirlpool t. No fragments of these * Hist. and Philos. of Earthquakes, p. 317. t Rev. C. Davy's Letters, vol. ii., Letter ii., p. 12, who was at Lisbon at the time, and ascertained that the boats and vessels said to have been swallowed were missing. EARTHQUAKE OF LfSBON, A.D. 1755. 439 wrecks ever rose again t th f: . Place wh ere the qnay ha..J o t de s· ur ace, da n.d the water m the 'n s oo 1s state , m many accounts, to be unfathomable; but Whitehurst;~ h . d . to be one I1 undred fathom' s. says, e ascertame 1t In this case, we must either suppose th t . sank. down I. nto a subterranean hollow whicha a cledr tam tract "1"a u 1t " m· t h e strata to the depth of six hundwr odu cause a J! t • .l' e 1ee , or we may m1er, as some have done from tlJe entr'r·e a· , Isappearance of ~he substa~ces eng~lphed, that a chasm opened and closed agam. Yet, m adoptmg this latter hypothesis, we must suppose that the upper part of the chasm, to the depth of one hundred fathoms, remained open. The great area over which this Lisbon earthquake extended is very remarkable. The movement was most violent in Spain Portugal, and the north of Africa ; but nearly the whole of Europe, and even the West Indies, felt the shock on the same day. A sea-port, called St. Eubals, about twenty miles south of Lisbon, was engulphed. At Algiers and Fez, in Africa, the agitation of the cart!~ was equally violent, and at the distance of eight leagues from Morocco, a village, with the inhabitants to the number of about eight or ten thousand persons together with all the.ir cattle, were swallowed up. Soon afte; the earth closed .agmn o~er t.hem. A great wave swept over the coast of Spam, and Is smd to have been sixty feet high at Cadiz. At Tangier, in Africa, it rose and fell eighteen times on the coast. At Funchal, in Madeira, it rose full fifteen feet perpendicular above high-water mark, although the tide which ebbs and flows there seven feet was then at half ebb. Besides entering that city, and committing great havoc, it overflowed other sea-ports in the island. At Kinsale, in Ireland, a body of water rushed into the harbour, whirled round several vessels, and poured into the market place. The shock was felt at sea, on the deck of a ship to the west of Lisbon, and produced very much the same sensation as on dry land. Off St. Lucar, the captain of the Nancy frigate felt his ship so violently shaken that he thought he had struck the ground; but, on heaving the lead, found he was in a great depth of water. Captain Clark from Denia, in north latitude • On the Formation of the Earth, p. 55. |