ap, fig. 39, p. 351).[679]

_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 underground, 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 some 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.[680] 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 may
have given rise to this appearance.

The area over which this convulsion extended is very remarkable. It has
been computed, says Humboldt,[681] that on the 1st November, 1755, a
portion of the earth's surface four times greater than the extent of
Europe was simultaneously shaken. The shock was felt in the Alps, and on
the coast of Sweden, in small inland lakes on the shores of the Baltic,
in Thuringia, and in the flat country of northern Germany. The thermal
springs of Toplitz dried up, and again returned, inundating every thing
with water discolored by ochre. In the islands of Antigua, Barbadoes,
and Martinique in the West Indies, where the tide usually rises little
more than two feet, it suddenly rose above twenty feet, the water being
discolored and of an inky blackness. The movement was also sensible in
the great lakes of Canada. At Algiers and Fez, in the north of Africa,
the agitation of the earth was as violent as in Spain and Portugal; and
at the distance of eight leagues from Morocco, a village with the
inhabitants, to the number of about 8000 or 10,000 persons, are said to
have been swallowed up; the earth soon afterwards closing over them.

_Subsidence of the quay._--Among other extraordinary events related to
have 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 wh