From A. de Hum-boldt's Personal Narrative of Travels, translated by Helen Maria Williams.

"It is a very old and commonly received opinion at Cum-ana, Acapulca, and Lima, that a perceptible connection exists between earthquakes, and the state of the atmosphere that precedes these phenomena. On the coast of New Andalusia, the inhabitants are alarmed, when, in excessively hot weather, and after long- droughts, the breeze suddenly ceases to blow, and the sky, clear and without clouds at the zenith, exhibits near the horizon, at six or eight degrees elevation, the appearance of a reddish vapour. These prognostics are however very uncertain; and when the whole of the meteorological variations, at the times when the globe has been the most agitated, are called to mind, it is found, that violent shocks take place equally in dry and in wet weather, when the coolest winds blow, or during a dead and suffocating calm. From the great number of earthquakes, which I have witnessed to the north and south of the equator; on the continent, and in the bason of the seas; on the coasts, and at 2500 toises height; it appears to me, that the oscillations are generally very independent of the previous state of the atmosphere. This opinion is embraced by a number of enlightened persons, who inhabit the Spanish colonies; and whose experience extends, if not over a greater space of the globe, at least to a greater number of years than mine. On the contrary, in parts of Europe where earthquakes are rare compared to America, natural philosophers are inclined to admit an intimate connection between the undulations of the ground, and certain meteors, which usually take place at the same epocha. In Italy, for instance, the sirocco and earthquakes are suspected to have some connection; and at London, the frequency of falling stars, and those southern lights which have since been often observed by Mr. Dalton, were considered as the fore-runners of those shocks which were felt from 1748 to 1756.

Effects Of An Earthquake.

The engraving represents the great earthquake of 1755, in which the city of Lisbon, in Portugal, was entirely destroyed, and 20,000 persons were killed.

"On the days when the earth is agitated by violent shocks, the regularity of the horary variations of the barometer is not disturbed under the tropics. I have verified this observation at Cumana, at Lima, and at Riobamba; and it is so much the more worthy of fixing the attention of natural philosophers, as in St. Domingo, at the town of Cape Francois, it is asserted that a water barometer was observed to sink two inches and a half immediately before the earthquake of 1770. It is also related, that at the time of the destruction of Oran, a druggist fled with his family, because, observing accidentally, a Few minutes before the earthquake, the height of the mercury in his barometer, he perceived that the column sunk in an extraordinary manner. I know not whether we can give credit to this assertion: but as it is nearly impossible to examine the variations of the weight of the atmosphere during the shocks, we must be satisfied in observing the barometer before or after these phenomena have taken place. In the temperate lone, the aurora borealis does not always modify the variation of the needle, and the intensity of the magnetic forces: perhaps also earthquakes do not act constantly in the same manner on the air that surrounds us.

"We can scarcely doubt, that the earth, when opened and agitated by shocks, occasionally sends forth gaseous exhalations through the atmosphere, in places remote from the mouths of volcanoes not extinct. At Cumana, as we have already observed, flames and vapours, mixed with sulphureous acid, spring up from the most arid soil. In other parts of the same province, the earth ejects water and petroleum. At Rio-bamba, a muddy and inflammable mass, which is called moya, issues from crevices that close again, and accumulates into elevated hills. At seven leagues from Lisbon, near Colares, during the terrible earthquake of the 1st of November, 1755, flames, and a column of thick smoke, were seen to issue from the flanks of the rocks of Alvidras, and, according to some witnesses, from the bosom of the sea. This smoke lasted several days, and it was the more abundant in proportion as the subterraneous noise, which accompanied the shocks, was louder.

"Elastic fluids thrown into the atmosphere may act locally on the barometer, not by their mass, which is very small compared to the mass of the atmosphere; but because, at the moment of the great explosions, an ascending current is probably formed, which diminishes the pressure of the air. I am inclined to think, that in the greater number of earthquakes, nothing escapes from the agitated earth, and that, when gaseous exhalations and vapours take place, they oftener accompany or follow, than precede, the shocks. This last circumstance explains a fact, which seems indubitable; I mean that mysterious influence, in equinoctial America, of earthquakes accompanying a change of climate, and the order of the dry and rainy seasons. If the earth generally acts on the air only at the moment of the shocks, we can conceive why it is so rare that a sensible meteorological change becomes the presage of these great revolutions of nature.

"The hypothesis, according to which, in the earthquakes of Cumana, elastic fluids escape from the surface of the soil, seems confirmed by the observation of the dreadful noise which is heard during the shocks at the borders of the wells in the plain of Charas. Water and sand are sometimes thrown out twenty feet high. Similar phenomena have not escaped the observation of the ancient inhabitants of Greece and Asia Minor, abounding with caverns, crevices, and subterraneous rivers. Nature, in its uniform progress, every where suggests the same ideas of the causes of earthquakes, and the means by which man, forgetting the measure of his strength, oretends to diminish the effect of the subterraneous explosions