Volcanoes in the different regions of the Earth. 229 



plosion of the volcano of St Vincent, in the Lesser Antilles, 

 took place at a distance of 130 leagues. At the same moment 

 when this eruption happened, on the 30th April 1811, a sub- 

 terranean noise was propagated, and carried terror over an ex- 

 tent of country of 2200 square leagues. The inhabitants of the 

 banks of the Apure, at the confluence of the Rio Nula, as well 

 as those of the sea coast, compared the noise to that produced 

 by the discharge of large pieces of artillery. Now, from the 

 confluence of the Rio Nula and Apure, by which I arrived at the 

 Oronocco, to the volcano of St Vincent, the distance is 157 

 leagues in a straight line. This noise, which assuredly was not 

 propagated by the air, must have had its cause deep in the earth. 

 Its intensity was scarcely greater on the shores of the Antilles, 

 near the volcano in action, than in the interior of the country. 



It would be useless to multiply examples ; but in order to 

 recall to mind a phenomenon which has acquired a historical 

 importance with reference to Europe, I shall now mention the 

 famous earthquake of Lisbon. It took place on the 1st Novem- 

 ber 1755. Not only were the waters of the Swiss Lakes, and 

 of the sea on the coasts of Sweden, violently agitated ; but also 

 those of the sea around the eastern Antilles. At Martinique, 

 Antigua, and Barbadoes, where the tide does not commonly rise 

 more than eighteen inches, it suddenly rose twenty feet. All 

 these phenomena prove, that the subterranean powers manifest 

 themselves, either dynamically, by earthquakes, or chemically, 

 by occasioning changes in the form of volcanic eruptions. They 

 also demonstrate, that these powers act, not superficially in the 

 outer crust of the earth, but at immense depths in the interior 

 of our planet, by crevices and unfilled veins, which lead to points 

 of the earth's surface, at the greatest distances from each other. 



The more numerous the diversities in the structure of volca- 

 noes, or in other words, of the elevations surrounding the canals 

 by which the melted masses of the interior of the globe arrive 

 at its surface, so much the more important is it to submit this 

 structure to accurate measurements. The interest of these mea- 

 surements, which, in another part of the world, have formed 

 the object of my researches, increases if we consider that the 

 magnitude to be measured varies in several points. The phi- 

 losophical examination of nature applies itself, in the vicissitude 



