gypseous grottoes, and of the great chambers (sinkwerke) dug in mines of fossil salt which are worked by the introduction of fresh water. The caverns of calcareous mountains are not exposed to those decompositions of the atmospheric air, unless they contain bones of quadrupeds, or the mould mixed with animal gluten and phosphate of lime, from which arise inflammable and fetid gases. Though we made many enquiries among the inhabitants of Caripe, Cumanacoa, and Cariaco, we did not learn that they had ever discovered in the cavern of Guacharo either the remains of carniverous animals, or those bony breccias of herbivorous animals, which are found in the caverns of Germany and Hungary, and in the clefts of the calcareous rocks of Gibraltar. The fossil bones of the megatherium, of the elephant, and of the mastodon, which travellers have brought from South America, have all been found in the light soil of the valleys and table-lands. Excepting the megalonyx, a kind of sloth of the size of an ox, described by Mr. Jefferson, I know not a single instance of the skeleton of an animal buried in a cavern of the New World. The extreme scarcity of this geological phenomenon will appear the less surprising to us, if we recollect, that in France, England, and Italy, there are also a great number of grottoes in which we have never met with any vestige of fossil bones. * Although, in primitive nature, whatever relates to ideas of extent and mass is of no great importance, yet I may observe, that the cavern of Caripe is one of the most spacious known to exist in limestone formations. It is at least 900 metres or 2800 feet in length. Owing to the different degrees of solubility in rocks, it is generally not in calcareous mountains, but in gypseous formations, that we find the most extensive succession of grottoes. In Saxony there are some in gypsum several leagues in length; * The megalonyx was found in the caverns of Green Briar, in Virginia, at the distance of 1500 leagues from the megatherium, which resembles it very much, and is of the size of the rhinoceros. The famous Baumannshöhle in the Hartz, according to Messrs. Gilbert and Ilsen, is only 578 feet in length; the cavern of Scharzfeld 350; that of Gaylenreuth 304; that of Antiparos 300. But according to Saussure, the Grotto of Balme is 1300 feet long. 270 GENERAL TEMPERATURE. for instance, that of Wimelburg, which communicates with the cavern of Cresfield. The determination of the temperature of grottoes presents a field for interesting observation. The cavern of Caripe, situated nearly in the latitude of 10° 10', consequently in the centre of the torrid zone, is elevated 506 toises above the level of the sea in the gulf of Cariaco. We found that, in every part of it, in the month of September, the temperature of the internal air was between 18.4° and 18.9° of the centesimal thermometer; the external atmosphere being at 16.2°. At the entrance of the cavern, the thermometer in the open air was at 17·6°; but when immersed in the water of the little subterranean river, it marked, even to the end of the cavern, 16.8°. These experiments are very interesting, if we reflect on the tendency to equilibrium of heat, in the waters, the air, and the earth. When I left Europe, men of science were regretting that they had not sufficient data on what is called, 'the temperature of the interior of the globe;' and it is but very recently that efforts have been made, and with some success, to solve the grand problem of subterranean meteorology. The stony strata that form the crust of our planet, are alone accessible to our examination; and we now know that the mean temperature of these strata varies not only with latitudes and heights, but that, according to the position of the several places, it performs also, in the space of a year, regular oscillations round the mean heat of the neigbouring atmosphere. The time is gone by when men were surprised to find, in other zones, the heat of grottoes and wells differing from that observed in the caves of the observatory at Paris. The same instrument which in those caves marks 12°, rises in the subterraneous caverns of the island of Madeira, near Funchal, to 16.2°; in Joseph's Well, at Cairo* to 21.2°; in the grottoes of the island of Cuba to 22° or 23°. This increase is nearly in proportion to that of the mean temperature of the atmosphere, from latitude 48° to the tropics. * At Funchal (lat. 32° 37′) the mean temperature of the air is 20-4°, and at Cairo (lat. 30° 2′), according to Nouet, it is 22.4°. The mean temperature of the air at the Havannah, according to Mr. Ferrer, is 25.6°. GENERAL TEMPERATURE. 2713 We have just seen that, in the Cueva del Guacharo, the water of the river is nearly 2° colder than the ambient air of the cavern. The water, whether in filtering through the rocks, or in running over stony beds, doubtless imbibes the temperature of these beds. The air contained in the grotto, on the contrary, is not in repose; it communicates with the external atmosphere. Though under the torrid zone, the changes of the external temperature are exceedingly trifling, currents are formed, which modify periodically the internal air. It is consequently the temperature of the waters, that of 16.8°, which we might look upon as the temperature of the earth in those mountains, if we were sure that the waters do not descend rapidly from more elevated neighbouring mountains. It follows from these observations, that when we cannot obtain results perfectly exact, we find at least under each zone certain numbers which indicate the maximum and minimum. At Caripe, in the equinoctial zone, at an elevation of 500 toises, the mean temperature of the globe is not below 16.8°, which was the degree indicated by the water of the subterranean river. We can even prove that this temperature of the globe is not above 19°, since the air of the cavern, in the month of September, was found to be at 18.7°. As the mean temperature of the atmosphere, in the hottest month, does not exceed 19.5°,* it is probable that a thermometer in the grotto would not rise higher than 19° at any season of the year. The mean temperature of the month of September at Caripe is 18.5°; and on the coast of Cumana, where we had opportunities of making numerous observations, the mean heat of the warmest months differs only 1.8° from that of the coldest. 272 LIFE AT THE MISSION. CHAPTER VIII. Departure from Caripe.-Mountain and Forest of Santa Maria.—Mission of Catuaro.-Port of Cariaco. THE days we passed at the Capuchin convent in the mountains of Caripe, glided swiftly away, though our manner of living was simple and uniform. From sunrise to nightfall we traversed the forests and neighbouring mountains, to collect plants. When the winter rains prevented us from undertaking distant excursions, we visited the huts of the Indians, the conuco of the community, or those assemblies in which the alcaldes every evening arrange the labours of the succeeding day. We returned to the monastery only when the sound of the bell called us to the refectory to share the repasts of the missionaries. Sometimes, very early in the morning, we followed them to the church, to attend the doctrina, that is to say, the religious instruction of the Indians. It was rather a difficult task to explain dogmas to the neophytes, especially those who had but a very imperfect knowledge of the Spanish language. On the other hand, the monks are as yet almost totally ignorant of the language of the Chaymas; and the resemblance of sounds confuses the poor Indians and suggests to them the most whimsical ideas. Of this I may cite an example. I saw a missionary labouring earnestly to prove that infierno, hell, and invierno, winter, were not one and the same thing; but as different as heat and cold. The Chaymas are acquainted with no other winter than the season of rains; and consequently they imagined the 'Hell of the whites' to be a place where the wicked are exposed to frequent showers. The missionary harangued to no purpose: it was impossible to efface the first impression produced by the analogy between the two consonants. He could not separate in the minds of the neophytes the ideas of rain and hell; invierno and infierno. After passing almost the whole day in the open air, we employed our evenings, at the convent, in making notes, CLOUDY ATMOSPHERE. 273 drying our plants, and sketching those that appeared to form new genera. Unfortunately the misty atmosphere of a valley, where the surrounding forests fill the air with an enormous quantity of vapour, was unfavourable to astronomical observations. I spent a part of the nights waiting to take advantage of the moment when some star should be visible between the clouds, near its passage over the meridian. I often shivered with cold, though the thermometer only sunk to 16°, which is the temperature of the day in our climates towards the end of September. The instruments remained set up in the court of the convent for several hours, yet I was almost always disappointed in my expectations. Some good observations of Fomalhaut and of Deneb have given 10° 10′ 14′′ as the latitude of Caripe; which proves that the position indicated in the maps of Caulin is 187 wrong, and in that of Arrowsmith 14'. Observations of corresponding altitudes of the sun having given me the true time, within about 2", I was enabled to determine the magnetic variation with precision, at noon. It was, on the 20th of September, 1799, 3° 15′ 30′′ north-east; consequently 0° 58′ 15′′ less than at Cumana. If we attend to the influence of the horary variations, which in these countries do not in general exceed 8', we shall find, that at considerable distances the variation changes less rapidly than is usually supposed. The dip of the needle was 42-75°, centesimal division, and the number of oscillations, expressing the intensity of the magnetic forces, rose to 229 in ten minutes. The vexation of seeing the stars disappear in a misty sky was the only disappointment we felt in the valley of Caripe. The aspect of this spot presents a character at once wild and tranquil, gloomy and attractive. In the solitude of these mountains we are perhaps less struck by the new impressions we receive at every step, than with the marks of resemblance we trace in climates the most remote from each other. The hills by which the convent is backed, are crowned with palmtrees and arborescent ferns. In the evenings, when the sky denotes rain, the air resounds with the monotonous howling of the alouate apes, which resembles the distant sound of wind when it shakes the forest. Yet amid these strange sounds, these wild forms of plants, and these prodigies of a new world, nature everywhere speaks to man in a voice VOL. I. T |