ave never been more terribly
illustrated than in the case of the earthquake of Lisbon which took
place on November 1, 1755. The inhabitants had no warning of the coming
danger, when a sound like that of thunder was heard underground, and
immediately afterwards a violent shock threw down the greater part of
their city; this was the land-wave. In the course of about six minutes,
sixty thousand persons perished. The sea first retired and left the
harbour dry, so forming the trough in front of the crest; immediately
after the water rolled in with a lofty crest, some 50 feet above the
ordinary level, flooding the harbour and portions of the city bordering
the shore. The mountains of Arrabida, Estrella, Julio, Marvan, and
Cintra, were impetuously shaken, as it were, from their very
foundations; and according to the computation of Humboldt, a portion of
the earth's surface four times the extent of Europe felt the effects of
this great seismic shock, which extended to the Alps, the shores of the
Baltic, the lakes of Scotland, the great lakes of North America, and
the West Indian Islands. The velocity of the sea-wave was estimated at
about 20 miles per minute.

(_f._) _Earthquake of Lima and Callao, 28th October, 1746._--Of somewhat
similar character was the terrible catastrophe with which the cities of
Lima and Callao were visited in the middle of the last century,[6] in
which the former city, then one of great magnificence, was overthrown;
and Callao was inundated by a sea-wave, in which out of 23 ships of all
sizes in the harbour the greater number foundered; several, including a
man-of-war, were lifted bodily and stranded, and all the inhabitants
with the exception of about two hundred were drowned. A volcano in
Lucanas burst forth the same night, and such quantities of water
descended from the cone that the whole country was overflowed; and in
the mountain near Pataz, called Conversiones de Caxamarquilla, three
other volcanoes burst forth, and torrents of water swept down their
sides. In the case of these cities, the land-wave, or shock, preceded
the sea-wave, which of course only reached the port of Callao.

[Illustration: Fig. 37.--The lines represent isoseismal curves, or
curves of equal intensity, the force decreasing outwards from the focus
at Charleston, No. 10.]

(_g._) _Earthquake of Charleston, 31st August, 1886._--I shall close
this account of some remarkable earthquakes with a few facts regarding
that of Charl