These tremblings and rockings of the earth, that seem so terrible to us Europeans, are such ordinary occurrences in the environs of San Salvador that the district has acquired the name of the "swinging mat;" but these shocks, though frequent, had never been hitherto of the violent and destructive character which they have assumed at Valparaiso and Lima, where about once in a century the destruction of a town is reckoned on as a matter of course. The volcano of Isalco, too, being in constant activity, and only forty-eight miles south of the city of San Salvador, had always been regarded as a chimney and safety-valve, affording a free vent for the steam and other dangerous products of the subterranean furnace. The shocks were repeated at tolerably regular intervals, two or three in an hour, during the whole of the Good Friday, and all had the same direction,--namely, from west-southwest to east-northeast; at which point, a league from the town, lies the great crater of Cuscatlan, about five hundred feet above San Salvador. The ceremonies of the Good Friday proceeded with the accustomed pomp, and people did not think of disturbing their processions, or their visits to the cathedral, on account of the earthquake; though occasionally, when there came a shock rather stronger than usual, some of the devout crowd did turn pale and make a rush towards the doors. At half-past nine in the evening there came a shock so violent that the houses were shaken to the foundations, the roofs cracked, plaster and tiles fell, and the walls in many places were rent. The houses are all low and broad, without upper stories, the walls mostly of clay, which is very elastic, and the rafters made of pliable, closely-plaited cane, admirably adapted to resist the most violent shocks; otherwise the houses would have fallen in a mass with this one, which lasted eight seconds, the ground undulating like the ocean. Every one rushed out into the open air, but a full hour passed without any further movement. We determined, nevertheless, not to sleep under a roof; but my countryman, Mr. Kronmeier, the Prussian vice-consul, who came home about eleven o'clock, laughed at our caution, and went to bed as usual in his bedroom. He was used to these unpleasant occurrences; though he confessed that, during a residence of sixteen years in Central America and Mexico, he had never felt in one day so many shocks as during the one just past.