IN OTHER DISTRICTS. l43 



not less than fifteen oscillations were felt in one day. chap. xili. 

 On the 6th April there was an earthquake almost as Number of 

 severe as that of the 12th March. The surface was in oscillations 

 continuous undulation during several hours, large masses 

 of earth fell in the mountains, and enormous rocks were 

 detached from the Silla. 



While violent agitations were experienced in the Subterra- 

 valley of the Mississippi, in the island of St Vincent, •'«™ ^"-^^ 

 and in the province of Venezuela, a subterranean noise, 

 resembling an explosion of artillery, was heard at 

 Caraccas, at Calabozo, and on the banks of the Rio Apure, 

 over the space of four thousand square leagues. This 

 sound began at two in the morning of the 80th April, 

 and was as loud on the coast as at the distance of 270 

 miles. It was every where taken for the firing of guns, volcanic 

 On the same day a great eruption of the volcano of the |l"^-'°".''t 

 island of St Vincent took place. This mountain had 

 not ejected lava since 1718, and hardly any smoke was 

 issuing from it, when in May 1811 frequent shocks 

 occurred, and a discharge of ashes, attended with a 

 tremendous bellowing, followed on the 27th April next 

 year. On the 80th the lava overflowed, and after a 

 course of four hours reached the sea. The explosions 

 resembled alternate volleys of very large cannon and 

 musketry. As the space between the volcano of St 

 Vincent and the Rio Apure is 725 miles, these were 

 heard at a distance equal to that between Vesuvius and 

 Paris, and must have been propagated by the earth, and 

 not by the air. 



After adducing numerous instances of the coincidence subterra- 

 of volcanic eruptions and earthquakes, Humboldt en- nean tom- 

 deavours to prove that subterranean communications 

 extend to vast distances, that the phenomena of volca- 

 noes and earthquakes are intimately connected, and 

 that the latter have certain lines of direction. 



