382 STRUCTURE, AND MODE OF ACTION 



first the West Indian Islands, then the plain of the Ohio and Mis- 

 sissippi, and lastly, the opposite coast of Venezuela or Caraccas. 

 Thirty days after the destruction of the principal city of that pro- 

 vince, the long tranquil volcano of the Island of St. Vincent burst 

 forth in an eruption. A remarkable phenomenon accompanied this 

 eruption : at the same moment when the explosion took place, on 

 the 30th of April, 1811, a loud subterranean noise was heard in 

 South America, which spread terror and dismay over a district of 

 2200 (German) geographical square miles (35,200 English geo- 

 graphical square miles). The dwellers on the banks of the Apure, 

 near the confluence of the Rio Nula, and the most distant inhabitants 

 of the sea coast of Venezuela, alike compared the sound to that of 

 the discharge of great pieces of ordnance. Now from the confluence 

 of the Nula with the Apure (by which latter river I arrived on the 

 Orinoco) to -die volcano of St. Vincent is a distance in a straight 

 line of 628 English geographical miles. The sound, which certainly 

 was not propagated through the air, must have proceeded from a 

 deep-seated subterranean cause; for its intensity was scarcely greater 

 on the sea coast nearest to the volcano where the eruption was 

 'taking place, than in the interior of the country, in the basin of 

 the Apure and the Orinoco. 



It would be unnecessary to multiply examples by citing other 

 instances which I have collected ; but, to recall a phenomenon of 

 European historical importance, I will only farther mention the 

 celebrated earthquake of Lisbon. Simultaneously with that event, 

 on the 1st of November, 1755, not only were the Swiss lakes and 

 the sea near the coast of Sweden violently agitated, but even among 

 the eastern West Indian Islands, Martinique, Antigua, and Bar- 

 badoes, where the tide never exceeds thirty inches, the sea suddenly 

 rose more than twenty feet. All these phenomena show the opera- 

 tion of subterranean forces, acting either dynamically in earthquakes, 

 in the tension and agitation of the crust; or in volcanos, in the 

 production and chemical alteration of substances. They also show 

 that these forces do not act superficially, in the thin outermost crust 

 of the globe, but from great depths in the interior of our planet, 

 through crevices or unfilled veins, affecting simultaneously widely 

 distant points of the earth's surface. 



