PHENOMENA ATTENDING EARTHQUAKES. 259 



come more severe, and frequeni, so that the movement of the 

 earth is apparent to the most inexperienced. It is now that the 

 subterranean thunder is heard, and the walls of buildings begin 

 to gape open, and close, rendering it exceedingly dangerous to re- 

 main in them. The fields and tho mountains, at such times, af- 

 ford no secure shelter, the former are often rent asunder, open- 

 ing enormous fissures, which engulph thousands, and then close 

 again, while the nountains are rent, and slide down into the val- 

 leys, damming up the rivers and lakes, and causing tremendous 

 inundations. At such times, the bed of the ocean appears as un- 

 stable as the dry land; vast waves, sometimes fifty or sixty feet 

 in height, are rolled along the coast, and then retire, leaving the 

 whole shore dry. Ships at sea, often experience these extraor- 

 dinary movements, even at a distance of 250 miles from land, 

 seeming as violently agitated as though grating over a ledge of 

 rocks, and suddenlv striking on the ground, and often with such 

 violence as to open the seams of the vessel. The duration of a 

 single shock rarely exceeds half ^second. In this short space of 

 time, thousands of human beings have found a common grave, 

 and whole cities have been swallowed up. The interval whicb 

 elapses between successive shocks is variable; sometimes they 

 succeed with considerable rapidity, and at other times happen 

 after an interval of months, or even years. The first shock is 

 not always the most violent, though in some particular regions of 

 country, Syria, for example, the first catastrophe is always the 

 most destructive; generally however, the second shock is mow 

 violent The extent of country agitated by some great earth- 

 quakes is very remarkable; thus the momentary upheaving of the 

 bed of the ocean, during the earthquake of 1755, which destroy- 

 ed Lisbon, caused the sea to overflow the coasts of Sweden, 

 England, and Spain, and the islands of Antigua, Barbadoes, and 

 Martinique, in America; at Barbadoes, the tide rose nearly 18 

 feet above high water mark, and the^ water was brack as ink from 

 the presence of bituminous matter. On the 1st of ^ November, 

 when the concussions appeared most violent, the water at Gua- 

 ^dalope retreated twice, and on its return rose in the channel of 

 die island 10 or 12 feet in height A wave of the sea, 60 fe*t 



