EARTHQUAKES AND THEIR CAUSES. 733 



" a hollow rumbling noise almost like that of thunder." At Colares, 

 near Lisbon, in 1755, during the great earthquake, the sound is said 

 to have been " like that of chariots, whicli increased till it equaled 

 that of the roar of cannon ; " and at Lisbon, " a rattling as of coaches 

 in the street, with a frightful noise underground resembling the 

 rumbling of distant thunder." At Madeira the same earthquake was 

 preceded " by rumbling noises in the air like that of empty carriages, 

 which died away like a peal of distant thunder," On the 16th of 

 September, 1849, there was an earthquake at Burra-Burra, in South 

 Australia, where the noise is said to have resembled the rolling of 

 heavy carriages. The shock was followed by a flash of lightning that 

 illumined the whole atmosphere. 



2. Another feature of these phenomena is the upheaval of the 

 ground observed during the prevalence of most earthquakes, which is 

 one cause of the sea retiring, another being the suction of the ap- 

 proaching wave when the centre of the convulsion has been removed 

 from the shore. During the great earthquake at Lisbon the bar at the 

 mouth of the Tagus was laid bare by the upheaval, and the master of 

 a vessel, lying in that river at the time, stated that his large anchor 

 was thrown up from the bottom, and seemed to swim on the surface 

 of the water. Other results of the iipward movement during this 

 catastrophe were observed elsewhere. The water in a pond at Dun- 

 stal, in Suftblk, was jerked up into the form of a pyramid. At some 

 places the water was tossed out of the wells. At Loch Lomond a 

 large stone was forced out of the water. Rocks were raised into the 

 air from the bottom of the Atlantic, and on board a vessel, about 

 forty leagues from the island of St. Vincent in the West Indies, the 

 anchors, which were lashed, bounced up, and the sailors thrown a foot 

 and a half perpendicular from the deck, the ship sinking into the water 

 immediately afterward as low as the main-chains. At Riobamba, in 

 South America, on the 5th of January, 1797, the bodies of many of 

 the inhabitants were thrown, by this vertical action, upon the hill of 

 La Cullca, which is sevei-al hundred feet high, and on the opposite 

 side of the river. During some of these convulsions in Italy, paving- 

 stones have been tossed into the air and found with their lower sides 

 uppermost ; and, at the time of a late convulsion in South America, 

 the rising of the ground caused the sea to retire, which returned like 

 a wall in appearance, carrying before it inland vessels that had only 

 a few minutes before been left dry, towns and people being over- 

 whelmed by the resistless recoil. 



3. Another peculiarity to be noticed in these convulsions is the 

 frequent horizontal and circular motion of the soil. These efiects are 

 often very curious, and, in countries much subject to such catastroj^hes 

 in their severest forms, have often given rise to lawsuits. Walls that 

 had served to divide fields have been completely changed in direction, 

 but without having been shattered or overthrown. Straight and par 



