attended with a tremendous noise. On the 30th, the lava passed the brink of the crater, and, after a course of four hours, reached the sea. The noise of the explosion "resembled that of alternate discharges of very large cannon and of musketry; and, which is well worthy of remark, it seemed much louder at sea, at a great distance from the island, than in sight of land, and near the burning volcano."

The distance in a straight line from the volcano of St. Vincent to the rio Apura, near the mouth of the Nula, is two hundred and ten leagues *. The explosions were consequently heard at a distance equal to that between Vesuvius and Paris. This phenomenon, connected with a great number of facts observed in the Cordilleras of the Andes, shows how much more extensive the subterranean sphere of activity of a volcano is, than we are disposed to admit from the small changes effected at the surface of the Globe. The detonations heard during whole days together in the New World, eighty, one hundred, or even two hundred leagues distant from a crater, do not reach us by the propagation of the sound through the air; they are transmitted to us by the ground, perhaps in the

Where the contrary is not expressly stated, nautical leagues of twenty to a degree, or two thousand eight hundred and fifty-five toises, are always to be understood.

.

very place where we happen to be. If the eruptions of the volcano of St. Vincent, Cotopaxi, or Tunguragua, resounded from afar, like a cannon of an immense magnitude, the noise ought to have increased in the inverse ratio of the distance: but observations prove, that this augmentation does not take place. I must further observe, that Mr. Bonpland and I, going from Guayaquil to the coast of Mexico, crossed latitudes in the South Sea, where all the mariners of our ship were affrighted by a hollow sound, that came from the depth of the ocean, and was transmitted to us by the waters. It was the period of a new eruption of Cotopaxi, and we were as far distant from that volcano, as Etna from the city of Naples. The little town of Honda, on the banks of the Magdalena, is not less than one hundred and forty-five leagues * from Cotopaxi; and yet in the great explosions of this volcano, in 1744, a subterraneous noise was heard at Honda, and supposed to be discharges of heavy artillery. The monks of St. Francis spread the news, that the town of Carthagena was besieged and bombarded by the English; and the intelligence was believed 'throughout the country. Now the volcano of Cotopaxi is a cone, more than one thousand eight hundred toises above the basin of Honda,

This is the distance from Vesuvius to Mont Blanc.

and rises from a table-land, the elevation of which is more than one thousand five hundred toises above the valley of the Magdalena. In all the colossal mountains of Quito, of the province of Los Pastos, and of Popayan, crevices and valleys without number are interposed. It cannot be admitted, under these circumstances, that the noise could be transmitted through the air, or by the superior surface of the Globe, and that it came from that point, where the cone and crater of Cotopaxi are placed. It appears probable, that the higher part of the kingdom of Quito and the neighbouring Cordilleras, far from being a group of distinct volcanoes, constitute a single swollen mass, an enormous volcanic wall, stretching from South to North, and the crest of which exhibits a surface of more than six hundred square leagues. Cotopaxi, Tunguragua, Antisana, and Pichincha, are placed on this same vault, on this raised ground. They are differently named, although they are only different summits of the same volcanic mass. The fire issues sometimes from one, sometimes from another of these summits. The obstructed craters appear to us to be extinguished volcanoes; but we may presume, that, while Cotopaxi or Tunguragua have only one or two eruptions in the course of a century, the fire is not less continually active under the town of Quito, under Pichincha and Imbaburu.

Advancing toward the North, we find, between the volcano of Cotopaxi and the town of Honda, two other systems of volcanic mountains, those of Los Pastos and of Popayan. The connection of these systems was manifested in the Andes in an incontestible manner by a phenomenon, which I have already had occasion to notice, in speaking of the last destruction of Cumana. Since the month of November, 1796, a thick column of smoke had issued from the volcano of Pasto, West of the town of that name, and near the valley of rio Guaytara. The mouths of the volcano are lateral, and placed on its western declivity, yet during three successive months the column rose so much higher than the ridge of the mountain, that it was constantly visible to the inhabitants of the town of Pasto. They related to us their astonishment, when, on the 4th of February, 1797, they observed the smoke disappear in an instant, without feeling any shock whatever. At that very moment, sixty-five leagues to the South, between Chimborazo, Tunguragua, and the Altar (CapacUrcu), the town of Riobamba was overthrown by the most dreadful earthquake, of which tradition has transmitted the history. Is it possible to doubt from this coincidence of phenomena, that the vapours, issuing from the small apertures or ventanillas of the volcano of Pasto, had an influence on the pressure of those elastic

fluids, which shook the ground of the kingdom of Quito, and destroyed in a few minutes thirty or forty thousand inhabitants?

In order to explain these great effects of volcanic reactions, and to prove, that the group or system of the volcanoes of the West India Islands may sometimes shake the continent, it was necessary to cite the Cordillera of the Andes. Geological reasoning can be supported only on the analogy of facts that are recent, and consequently well authenticated: and in what other region of the Globe could we find greater and at the same time more varied volcanic phenomena, than in that double chain of mountains heaved up by fire? in that land, where Nature has covered every summit and every valley with her marvels? If we consider a burning crater only as an isolated phenomenon, if we satisfy ourselves with examining the mass of stony substances which it has thrown up, the volcanic action at the surface of the Globe will appear neither very powerful, nor very extensive. But the image of this action swells in the mind, when we study the relations that link together volcanoes of the same group; for instance those of Naples and Sicily, of the Canary islands*, of the Azores, of the Caribbee

I have already related, vol. 1, p. 249, how the whole group of the Canary islands are placed, as we may say, on one and the same submarine volcano; the fire of which,