With Respect To The Springs Which Gush Out In The Plains Of The Torrid Zone, Or At A Small Elevation,

It may be observed, in general, that it is only in regions where the mean temperature of summer essentially differs

From that of the whole year, that the inhabitants have extremely cold spring water during the season of great heat. The Laplanders, near Umea and Soersele, in the 65th degree of latitude, drink spring-water, the temperature of which, in the month of August, is scarcely two or three degrees above freezing point; while during the day the heat of the air rises in the shade, in the same northern regions, to 26 or 27 degrees. In the temperate climates of France and Germany, the difference between the air and the springs never exceeds 16 or 17 degrees; between the tropics it seldom rises to 5 or 6 degrees. It is easy to account for these phenomena, when we recollect that the interior of the globe, and the subterraneous waters, have a temperature almost identical with the annual mean temperature of the air; and that the latter differs from the mean heat of summer, in proportion to the distance from the equator.

From the top of a hill of sandstone, which overlooks the spring of Quetepe, we had a magnificent view of the sea, of cape Macanao, and the peninsula of Maniquarez. At our feet an immense forest extended to the edge of the ocean. The tops of the trees, intertwined with lianas, and crowned with long wreaths of flowers, formed a vast carpet of verdure, the dark tint of which augmented the splendour of the aerial light. This picture struck us the more forcibly, as we then first beheld those great masses of tropical vegetation. On the hill of Quetepe, at the foot of the Malpighia cocollobaefolia, the leaves of which are extremely coriaceous, we gathered, among tufts of the Polygala montana, the first melastomas, especially that beautiful species described under the name of the Melastoma rufescens.

As we advanced toward the south-west, the soil became dry and sandy. We climbed a group of mountains, which separate the coast from the vast plains, or savannahs, bordered by the Orinoco. That part of the group, over which passes the road to Cumanacoa, is destitute of vegetation, and has steep declivities both on the north and the south. It has received the name of the Imposible, because it is believed that, in the case of hostile invasion, this ridge of mountains would be inaccessible to the enemy, and would offer an asylum to the inhabitants of Cumana. We reached the top a little before sunset, and I had scarcely time to take a few horary angles, to determine the longitude of the place by means of the chronometer.

The view from the Imposible is finer and more extensive than that from the table-land of Quetepe. We distinguished clearly by the naked eye the flattened top of the Brigantine (the position of which it would be important to fix accurately), the embarcadero or landing-place, and the roadstead of Cumana. The rocky coast of the peninsula of Araya was discernible in its whole length. We were particularly struck with the extraordinary configuration of a port, known by the name of Laguna Grande, or Laguna del Obispo. A vast basin, surrounded by high mountains, communicates with the gulf of Cariaco by a narrow channel which admits only of the passage of one ship at a time. This port is capable of containing several squadrons at once. It is an uninhabited place, but annually frequented by vessels, which carry mules to the West India Islands. There are some pasture grounds at the farther end of the bay. We traced the sinuosities of this arm of the sea, which, like a river, has dug a bed between perpendicular rocks destitute of vegetation. This singular prospect reminded us of the fanciful landscape which Leonardo da Vinci has made the back-ground of his famous portrait of Mona Lisa, the wife of Francisco del Giacondo.

We could observe by the chronometer the moment when the disk of the sun touched the horizon of the sea. The first contact was at 6 hours 8 minutes 13 seconds; the second, at 6 hours 10 minutes 26 seconds; mean time. This observation, which is not unimportant for the theory of terrestrial refractions, was made on the summit of the mountain, at the absolute height of 296 toises. The setting of the sun was attended by a very rapid cooling of the air. Three minutes after the last apparent contact of the disk with the horizon of the sea, the thermometer suddenly fell from 25.2 to 21.3 degrees. Was this extraordinary refrigeration owing to some descending current? The air was however calm, and no horizontal wind was felt.

We passed the night in a house where there was a military post consisting of eight men, under the command of a Spanish serjeant. It was an hospital, built by the side of a powder magazine. When Cumana, after the capture of Trinidad by the English, in 1797, was threatened with an attack, many of the inhabitants fled to Cumanacoa, and deposited whatever articles of value they possessed in sheds hastily constructed on the top of the Imposible. It was then resolved, in case of any unforeseen invasion, to abandon the castle of San Antonio, after a short resistance, and to concentrate the whole force of the province round the mountains, which may be considered as the key of the Llanos.

The top of the Imposible, as nearly as I could perceive, is covered with a quartzose sandstone, free from petrifactions. Here, as on the ridge of the neighbouring mountains, the strata pretty regularly take the direction from north-north-east to south-south-west. This direction is also most common in the primitive formations in the peninsula of Araya, and along the coasts of Venezuela. On the northern declivity of the Imposible, near the Penas Negras, an abundant spring issues from sandstone, which alternates with a schistose clay.

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