The temperature of the atmosphere varied on the summit of the Silla from eleven to fourteen degrees, according as the weather was calm or windy. Every one knows how difficult it is to verify, on the summit of a mountain, the temperature, which is to serve for the barometric calculation. The wind was east, which would seem to prove that the trade-winds extend in this latitude much higher than fifteen hundred toises. Von Buch had observed that, at the peak of Teneriffe, near the northern limit of the trade-winds, there exists generally at the elevation of one thousand nine hundred toises, a contrary current from the west. The Academy of Sciences recommended the men of science who accompanied the unfortunate La Perouse, to employ small air-balloons for the purpose of ascertaining at sea the extent of the trade-winds within the tropics. Such experiments are very difficult. Small balloons do not in general reach the height of the Silla; and the light clouds which are sometimes perceived at an elevation of three or four thousand toises, for instance, the fleecy clouds, called by the French moutons, remain almost fixed, or have such a slow motion, that it is impossible to judge of the direction of the wind.
During the short space of time that the sky was serene at the zenith, I found the blue of the atmosphere sensibly deeper than on the coasts. It is probable that, in the months of July and August, the difference between the colour of the sky on the coasts and on the summit of the Silla is still more considerable, but the meteorological phenomenon with which M. Bonpland and myself were most struck during the hour we passed on the mountain, was the apparent dryness of the air, which seemed to increase as the fog augmented.
This fog soon became so dense that it would have been imprudent to remain longer on the edge of a precipice of seven or eight thousand feet deep.* (* In the direction of north-west the slopes appear more accessible; and I have been told of a path frequented by smugglers, which leads to Caravalleda, between the two peaks of the Silla. From the eastern peak I took the bearings of the western peak, 64 degrees 40 minutes south-west; and of the houses, which I was told belonged to Caravalleda, 55 degrees 20 minutes north-west. ) We descended the eastern dome of the Silla, and gathered in our descent a gramen, which not only forms a new and very remarkable genus, but which, to our great astonishment, we found again some time after on the summit of the volcano of Pichincha, at the distance of four hundred leagues from the Silla, in the southern hemisphere.* (* Aegopogon cenchroides.) The Lichen floridus, so common in the north of Europe, covered the branches of the befaria and the Gualtheria odorata, descending even to the roots of these shrubs. Examining the mosses which cover the rocks of gneiss in the valley between the two peaks, I was surprised at finding real pebbles,—rounded fragments of quartz.* (* Fragments of brown copper-ore were found mixed with these pebbles, at an elevation of 1170 toises.) It may be conceived that the valley of Caracas was once an inland lake, before the Rio Guayra found an issue to the east near Caurimare, at the foot of the hill of Auyamas, and before the ravine of Tipe opened on the west, in the direction of Gatia and Cabo Blanco. But how can we imagine that these waters could ascend as high as the Silla, when the mountains opposite this peak, those of Ocumare, were too low to prevent their overflow into the llanos? The pebbles could not have been brought by torrents from more elevated points, since there is no height that commands the Silla. Must we admit that they have been heaved up, like all the mountains which border the coast.
It was half after four in the afternoon when we finished our observations. Satisfied with the success of our journey, we forgot that there might be danger in descending in the dark, steep declivities covered by a smooth and slippery turf. The mist concealed the valley from us; but we distinguished the double hill of La Puerta, which, like all objects lying almost perpendicularly beneath the eye, appeared extremely near. We relinquished our design of passing the night between the two summits of the Silla, and having again found the path we had cut through the thick wood of heliconia, we soon arrived at the Pejual, the region of odoriferous and resinous plants. The beauty of the befarias, and their branches covered with large purple flowers, again rivetted our attention. When, in these climates, a botanist gathers plants to form his herbal, he becomes difficult in his choice in proportion to the luxuriance of vegetation. He casts away those which have been first cut, because they appear less beautiful than those which were out of reach. Though loaded with plants before quitting the Pejual, we still regretted not having made a more ample harvest. We tarried so long in this spot, that night surprised us as we entered the savannah, at the elevation of upwards of nine hundred toises.
As there is scarcely any twilight in the tropics, we pass suddenly from bright daylight to darkness. The moon was on the horizon; but her disk was veiled from time to time by thick clouds, drifted by a cold and rough wind. Rapid slopes, covered with yellow and dry grass, now seen in shade, and now suddenly illumined, seemed like precipices, the depth of which the eye sought in vain to measure. We proceeded onwards, in single file, and endeavoured to support ourselves by our hands, lest we should roll down. The guides, who carried our instruments, abandoned us successively, to sleep on the mountain. Among those who remained with us was a Congo black, who evinced great address, bearing on his head a large dipping-needle: he held it constantly steady, notwithstanding the extreme declivity of the rocks. The fog had dispersed by degrees in the bottom of the valley; and the scattered lights we perceived below us caused a double illusion. The steeps appeared still more dangerous than they really were; and, during six hours of continual descent, we seemed to be always equally near the farms at the foot of the Silla. We heard very distinctly the voices of men and the notes of guitars. Sound is generally so well propagated upwards, that in a balloon at the elevation of three thousand toises, the barking of dogs is sometimes heard.* (* Gay-Lussac's account of his ascent on the 15th of September, 1805.)
We did not arrive till ten at night at the bottom of the valley. We were overcome with fatigue and thirst, having walked for fifteen hours, nearly without stopping. The soles of our feet were cut and torn by the asperities of a rocky soil and the hard and dry stalks of the gramina, for we had been obliged to pull off our boots, the soles having become too slippery. On declivities devoid of shrubs or ligneous herbs, which may be grasped by the hand, the danger of the descent is diminished by walking barefoot. In order to shorten the way, our guides conducted us from the Puerta de la Silla to the farm of Gallegos by a path leading to a reservoir of water, called el Tanque. They missed their way, however; and this last descent, the steepest of all, brought us near the ravine of Chacaito. The noise of the cascades gave this nocturnal scene a grand and wild character.
We passed the night at the foot of the Silla. Our friends at Caracas had been able to distinguish us with glasses on the summit of the eastern peak. They felt interested in hearing the account of our expedition, but they were not satisfied with the result of our measurement, which did not assign to the Silla even the elevation of the highest summit of the Pyrenees.* (* It was formerly believed that the height of the Silla of Caracas scarcely differed from that of the peak of Teneriffe.) One cannot blame the national feeling which suggests exaggerated ideas of the monuments of nature, in a country in which the monuments of art are nothing; nor can we wonder that the inhabitants of Quito and Riobamba, who have prided themselves for ages on the height of Chimborazo, mistrust those measurements which elevate the mountains of Himalaya above all the colossal Cordilleras?
During our journey to the Silla, and in all our excursions in the valley of Caracas, we were very attentive to the lodes and indications of ore which we found in the strata of gneiss. No regular diggings having been made, we could only examine the fissures, the ravines, and the land-slips occasioned by torrents in the rainy season. The rock of gneiss, passing sometimes into a granite of new formation, sometimes into mica-slate,* (* Especially at great elevations.) belongs in Germany to the most metalliferous rocks; but in the New Continent, the gneiss has not hitherto been remarked as very rich in ores worth working. The most celebrated mines of Mexico and Peru are found in the primitive and transition schists, in the trap-porphyries, the grauwakke, and the alpine limestones. In several spots of the valley of Caracas, the gneiss contains a small quantity of gold, disseminated in small veins of quartz, sulphuretted silver, azure copper-ore, and galena; but it is doubtful whether these different metalliferous substances are not too poor to encourage any attempt at working them. Such attempts were, however, made at the conquest of the province, about the middle of the sixteenth century.
From the promontory of Paria to beyond cape Vela, the early navigators had seen gold ornaments and gold dust, in the possession of the inhabitants of the coast. They penetrated into the interior of the country, to discover whence the precious metal came; and though the information obtained in the province of Coro, and the markets of Curiana and Cauchieto,* (* The Spaniards found, in 1500, in the country of Curiana (now Coro), little birds, frogs, and other ornaments made of gold. Those who had cast these figures lived at Cauchieto, a place nearer the Rio de la Hacha. I have seen ornaments resembling those described by Peter Martyr of Anghiera (which indicate tolerable skill in goldsmiths' work), among the remains of the ancient inhabitants of Cundinamarca. The same art appears to have been practised in places along the coasts, and also farther to the south, among the mountains of New Grenada.) clearly proved that real mineral wealth was to be found only to the west and south-west of Coro (that is to say, in the mountains near those of New Grenada), the whole province of Caracas was nevertheless eagerly explored. A governor, newly arrived on that coast, could recommend himself to the Spanish court only by boasting of the mines of his province; and in order to take from cupidity what was most ignoble and repulsive, the thirst of gold was justified by the purpose to which it was pretended the riches acquired by fraud and violence might be employed. "Gold," says Christopher Columbus, in his last letter* (Lettera rarissima data nelle Indie nella isola di Jamaica a 7 Julio dei 1503.—"Le oro e metallo sopra gli altri excellentissimo; e dell' oro si fanno li tesori e chi lo tiene fa e opera quanto vuole nel mondo[?], e finel[?]mente aggionge a mandare le anime al Paradiso.") to King Ferdinand, "gold is a thing so much the more necessary to your majesty, because, in order to fulfil the ancient prophecy, Jerusalem is to be rebuilt by a prince of the Spanish monarchy. Gold is the most excellent of metals. What becomes of those precious stones, which are sought for at the extremities of the globe? They are sold, and are finally converted into gold. With gold we not only do whatever we please in this world, but we can even employ it to snatch souls from Purgatory, and to people Paradise." These words bear the stamp of the age in which Columbus lived; but we are surprised to see this pompous eulogium of riches written by a man whose whole life was marked by the most noble disinterestedness.
The conquest of the province of Venezuela having been begun at its western extremity, the neighbouring mountains of Coro, Tocuyo, and Barquisimeto, first attracted the attention of the Conquistadores. These mountains join the Cordilleras of New Grenada (those of Santa Fe, Pamplona, la Grita, and Merida) to the littoral chain of Caracas. It is a land the more interesting in a geognostical point of view, as no map has yet made known the mountainous ramifications which the paramos of Niquitao and Las Rosas send out towards the north-east. Between Tocuyo, Araure, and Barquisimeto, rises the group of the Altar Mountains, connected on the south-east with the paramo of Las Rosas. A branch of the Altar stretches north-east by San Felipe el Fuerte, joining the granitic mountains of the coast near Porto Cabello. The other branch takes an eastward direction towards Nirgua and Tinaco, and joins the chain of the interior, that of Yusma, Villa de Cura, and Sabana de Ocumare.