The wind freshened more and more from the south-east, as we advanced in the direction of Cape Negril and the western extremity of the great bank of La Vibora. We were often forced to diverge from our course; and, on account of the extreme smallness of our vessel, we were almost constantly under water. On the 18th of March at noon we found ourselves in latitude 18 degrees 17 minutes 40 seconds, and in 81 degrees 50 minutes longitude. The horizon, to the height of 50 degrees, was covered with those reddish vapours so common within the tropics, and which never seem to affect the hygrometer at the surface of the globe. We passed fifty miles west of Cape Negril on the south, nearly at the point where several charts indicate an insulated flat of which the position is similar to that of Sancho Pardo, opposite to Cape San Antonio de Cuba. We saw no change in the bottom. It appears that the rocky shoal at a depth of four fathoms, near Cape Negril, has no more existence than the rock (cascabel) itself, long believed to mark the western extremity of La Vibora (Pedro Bank, Portland Rock or la Sola), marking the eastern extremity. On the 19th of March, at four in the afternoon, the muddy colour of the sea denoted that we had reached that part of the bank of La Vibora where we no longer find fifteen, and indeed scarcely nine or ten, fathoms of water. Our chronometric longitude was 81 degrees 3 minutes; and our latitude probably below 17 degrees. I was surprised that, at the noon observation, at 17 degrees 7 minutes of latitude, we yet perceived no change in the colour of the water. Spanish vessels going from Batabano or Trinidad de Cuba to Carthagena, usually pass over the bank of La Vibora, on its western side, at between fifteen and sixteen fathoms water. The dangers of the breakers begin only beyond the meridian 80 degrees 45 minutes west longitude. In passing along the bank on its southern limit, as pilots often do in proceeding from Cumana or other parts of the mainland, to the Great Caymnan or Cape San Antonio, they need not ascend along the rocks, above 16 degrees 47 minutes latitude. Fortunately the currents run on the whole bank to south-west.
Considering La Vibora not as a submerged land, but as a heaved-up part of the surface of the globe, which has not reached the level of the sea, we are struck at finding on this great submarine island, as on the neighbouring land of Jamaica and Cuba, the loftiest heights towards its eastern boundary. In that direction are situated Portland Rock, Pedro Keys and South Key, all surrounded by dangerous breakers. The depth is six or eight fathoms; but, in advancing to the middle of the bank, along the line of the summit, first towards the west and then towards the north-west, the depth becomes successively ten, twelve, sixteen and nineteen fathoms. When we survey on the map the proximity of the high lands of San Domingo, Cuba and Jamaica, in the neighbourhood of the Windward Channel, the position of the island of Navaza and the bank of Hormigas, between Capes Tiburon and Morant; when we trace that chain of successive breakers, from the Vibora, by Baxo Nuevo, Serranilla, and Quita Sueno, as far as the Mosquito Sound, we cannot but recognize in this system of islands and shoals the almost-continued line of a heaved-up ridge running from north-east to south-west. This ridge, and the old dyke, which link, by the rock of Sancho Pardo, Cape San Antonio to the peninsula of Yucatan, divide the great sea of the West Indies into three partial basins, similar to those observed in the Mediterranean.
The colour of the troubled waters on the shoal of La Vibora has not a milky appearance like the waters in the Jardinillos and on the bank of Bahama; but it is of a dirty grey colour. The striking differences of tint on the bank of Newfoundland, in the archipelago of the Bahama Islands and on La Vibora, the variable quantities of earthy matter suspended in the more or less troubled waters of the soundings, may all be the effects of the variable absorption of the rays of light, contributing to modify to a certain point the temperature of the sea. Where the shoals are 8 to 10 degrees colder at their surface than the surrounding sea, it cannot be surprising that they should produce a local change of climate. A great mass of very cold water, as on the bank of Newfoundland, in the current of the Peruvian shore (between the port of Callao and Punta Parina* (* I found the surface of the Pacific ocean, in the month of October 1802 on the coast of Truxillo, 15.8 degrees centigrade; in the port of Callao, in November, 15.5; between the parallel of Callao and Punta Parina, in December, 19 degrees; and progressively, when the current advanced towards the equator and receded towards the west-north-west, 20.5 and 22.3 degrees)), or in the African current near Cape Verd, have necessarily an influence on the atmosphere that covers the sea, and on the climate of the neighbouring land; but it is less easy to conceive that those slight changes of temperature (for instance, a centesimal degree on the bank of La Vibora) can impart a peculiar character to the atmosphere of the shoals. May not these submarine islands act upon the formation and accumulation of the vesicular vapours in some other way than by cooling the waters of the surface?
Quitting the bank of La Vibora, we passed between the Baxo Nuevo and the light-house of Camboy; and on the 22nd March we passed more than thirty leagues to westward of El Roncador (The Snorer), a name which this shoal has received from the pilots who assert, on the authority of ancient traditions, that a sound like snoring is heard from afar. If such a sound be really heard, it arises, no doubt, from a periodical issuing of air compressed by the waters in a rocky cavern. I have observed the same phenomenon on several coasts, for instance, on the promontories of Teneriffe, in the limestones of the Havannah,* (* Called by the Spanish sailors El Cordonazo de San Francisco.) and in the granite of Lower Peru between Truxillo and Lima. A project was formed at the Canary Islands for placing a machine at the issue of the compressed air and allowing the sea to act as an impelling force. While the autumnal equinox is everywhere dreaded in the sea of the West Indies (except on the coast of Cumana and Caracas), the spring equinox produces no effect on the tranquillity of those tropical regions: a phenomenon almost the inverse of that observable in high latitudes. Since we had quitted La Vibora the weather had been remarkably fine; the colour of the sea was indigo-blue and sometimes violet, owing to the quantity of medusae and eggs of fish (purga de mar) which covered it. Its surface was gently agitated. The thermometer kept up, in the shade, from 26 to 27 degrees; not a cloud arose on the horizon although the wind was constantly north, or north-north-west. I know not whether to attribute to this wind, which cools the higher layers of the atmosphere, and there produces icy crystals, the halos which were formed round the moon two nights successively. The halos were of small dimensions, 45 degrees diameter. I never had an opportunity of seeing and measuring any* of which the diameter had attained 90 degrees. (* In Captain Parry's first voyage halos were measured round the sun and moon, of which the rays were 22 1/2 degrees; 22 degrees 52 minutes; 38 degrees; 46 degrees. North-west Passage, 1821.) The disappearance of one of those lunar halos was followed by the formation of a great black cloud, from which fell some drops of rain; but the sky soon resumed its fixed serenity, and we saw a long series of falling-stars and bolides which moved in one direction and contrary to that of the wind of the lower strata.
On the 23rd March, a comparison of the reckoning with the chronometric longitude, indicated the force of a current bearing towards west-south-west. Its swiftness, in the parallel of 17 degrees, was twenty to twenty-two miles in twenty-four hours. I found the temperature of the sea somewhat diminished; in latitude 12 degrees 35 minutes it was only 25.9 degrees (air 27.0 degrees). During the whole day the firmament exhibited a spectacle which was thought remarkable even by the sailors and which I had observed on a previous occasion (June 13th, 1799). There was a total absence of clouds, even of those light vapours called dry; yet the sun coloured, with a fine rosy tint, the air and the horizon of the sea. Towards night the sea was covered with great bluish clouds; and when they disappeared we saw, at an immense height, fleecy clouds in regular spaces, and ranged in convergent bands. Their direction was from north-north-west to south-south-east, or more exactly, north 20 degrees west, consequently contrary to the direction of the magnetic meridian.
On the 24th March we entered the gulf which is bounded on the east by the coast of Santa Marta, and on the west by Costa Rica; for the mouth of the Magdalena and that of the Rio San Juan de Nicaragua are on the same parallel, nearly 11 degrees latitude. The proximity of the Pacific Ocean, the configuration of the neighbouring lands, the smallness of the isthmus of Panama, the lowering of the soil between the gulf of Papagayo and the port of San Juan de Nicaragua, the vicinity of the snowy mountains of Santa Marta, and many other circumstances too numerous to mention, combine to create a peculiar climate in this gulf. The atmosphere is agitated by violent gales known in winter by the name of the brizotes de Santa Marta. When the wind abates, the currents bear to north-east, and the conflict between the slight breezes (from east and north-east) and the current renders the sea rough and agitated. In calm weather, the vessels going from Carthagena to Rio Sinu, at the mouth of the Atrato and at Portobello, are impeded in their course by the currents of the coast. The heavy or brizote winds, on the contrary, govern the movement of the waters, which they impel in an opposite direction, towards west-south-west. It is the latter movement which Major Rennell, in his great hydrographic work, calls drift; and he distinguishes it from real currents, which are not owing to the local action of the wind, but to differences of level in the surface of the ocean; to the rising and accumulation of waters in very distant latitudes. The observations which I have collected on the force and direction of the winds, on the temperature and rapidity of the currents, on the influence of the seasons, or the variable declination of the sun, have thrown some light on the complicated system of those pelagic floods that furrow the surface of the ocean: but it is less easy to conceive the causes of the change in the movement of the waters at the same season and with the same wind. Why is the Gulf-stream sometimes borne on the coast of Florida, sometimes on the border of the shoal of Bahama? Why do the waters flow, for the space of whole weeks, from the Havannah to Matanzas, and (to cite an example of the corriente por arriba, which is sometimes observed in the most eastern part of the main land during the prevalence of gentle winds) from La Guayra to Cape Codera and Cumana?
As we advanced, on the 25th of March, towards the coast of Darien, the north-east wind increased with violence. We might have imagined ourselves transported to another climate. The sea became very rough during the night yet the temperature of the water kept up (from latitude 10 degrees 30 minutes, to 9 degrees 47 minutes) at 25.8 degrees. We perceived at sunrise a part of the archipelago* of Saint Bernard, which closes the gulf of Morrosquillo on the north. (* It is composed of the islands Mucara, Ceycen, Maravilla, Tintipan, Panda, Palma, Mangles, and Salamanquilla, which rise little above the sea. Several of them have the form of a bastion. There are two passages in the middle of this archipelago, from seventeen to twenty fathoms. Large vessels can pass between the Isla Panda and Tintipan, and between the Isla de Mangles and Palma.) A clear spot between the clouds enabled me to take the horary angles. The chronometer, at the little island of Mucara, gave longitude 78 degrees 13 minutes 54 seconds. We passed on the southern extremity of the Placer de San Bernardo. The waters were milky, although a sounding of twenty-five fathoms did not indicate the bottom; the cooling of the water was not felt, doubtless owing to the rapidity of the current. Above the archipelago of Saint Bernard and Cape Boqueron we saw in the distance the mountains of Tigua. The stormy weather and the difficulty of going up against the wind induced the captain of our frail vessel to seek shelter in the Rio Sinu, or rather, near the Punta del Zapote, situated on the eastern bank of the Ensenada de Cispata, into which flows the river Sinu or the Zenu of the early Conquistadores. It rained with violence, and I availed myself of that occasion to measure the temperature of the rain-water: it was 26.3 degrees, while the thermometer in the air kept up, in a place where the bulb was not wet, at 24.8 degrees. This result differed much from that we had obtained at Cumana, where the rain-water was often a degree colder than the air.* (* As, within the tropics, it takes but little time to collect some inches of water in a vase having a wide opening, and narrowing towards the bottom, I do not think there can be any error in the observation, when the heat of the rain-water differs from that of the air. If the heat of the rain-water be less than that of the air it may be presumed that only a part of the total effect is observed. I often found at Mexico at the end of June, the rain at 19.2 or 19.4 degrees, when the air was at 17.8 and 18 degrees. In general it appeared to me that, within the torrid zone, either at the level of the sea, or on table-lands from 1200 to 1500 toises high, there is no rain but that during storms, which falls in large drops very distant from each other, and is sensibly colder than the air. These drops bring with them, no doubt, the low temperature of the high regions. In the rain which I found hotter than the air, two causes may act simultaneously. Great clouds heat by the absorption of the rays of the sun which strike their surface; and the drops of water in falling cause an evaporation and produce cold in the air. The temperature of rain-water, to which I devoted much attention during my travels, has become a more important problem since M. Boisgiraud, Professor of Experimental Philosophy at Poitiers, has proved that in Europe rain is generally sufficiently cold, relatively to the air, to cause precipitation of vapour at the surface of every drop. From this fact he traces the cause of the unequal quantity of rain collected at different heights. When we recollect that one degree only of cooling precipitates more water in the hot climate of the tropics, than by a temperature of 10 to 13 degrees, we may cease to be surprised at the enormous size of the drops of rain that fall at Cumana, Carthagena and Guayaquil.)
Our passage from the island of Cuba to the coast of South America terminated at the mouth of the Rio Sinu, and it occupied sixteen days. The roadstead near the Punta del Zapote afforded very bad anchorage; and in a rough sea, and with a violent wind, we found some difficulty in reaching the coast in our canoe. Everything denoted that we had entered a wild region rarely visited by strangers. A few scattered houses form the village of Zapote: we found a great number of mariners assembled under a sort of shed, all men of colour, who had descended the Rio Sinu in their barks, to carry maize, bananas, poultry and other provisions to the port of Carthagena. These barks, which are from fifty to eighty feet long, belong for the most part to the planters (haciendados) of Lorica. The value of their largest freight amounts to about 2000 piastres. These boats are flat-bottomed, and cannot keep at sea when it is very rough. The breezes from the north-east had, during ten days, blown with violence on the coast, while, in the open sea, as far as 10 degrees latitude, we had only had slight gales, and a constantly calm sea. In the aerial, as in the pelagic currents, some layers of fluids move with extreme swiftness, while others near them remain almost motionless. The zambos of the Rio Sinu wearied us with idle questions respecting the purpose of our voyage, our books, and the use of our instruments: they regarded us with mistrust; and to escape from their importunate curiosity we went to herborize in the forest, although it rained. They had endeavoured, as usual, to alarm us by stories of boas (traga-venado), vipers and the attacks of jaguars; but during a long residence among the Chayma Indians of the Orinoco we were habituated to these exaggerations, which arise less from the credulity of the natives, than from the pleasure they take in tormenting the whites. Quitting the coast of Zapote, covered with mangroves,* (* Rhizophora mangle.) we entered a forest remarkable for a great variety of palm-trees. We saw the trunks of the Corozo del Sinu* pressed against each other, which formed heretofore our species Alfonsia, yielding oil in abundance (* In Spanish America palm-trees with leaves the most different in kind and species are called Corozo: the Corozo del Sinu, with a short, thick, glossy trunk, is the Elaeis melanococca of Martius, Palm. page 64 tab. 33, 55. I cannot believe it to be identical with the Elaeis guineensis (Herbal of Congo River page 37) since it vegetates spontaneously in the forests of the Rio Sinu. The Corozo of Caripe is slender, small and covered with thorns; it approaches the Cocos aculeata of Jacquin. The Corozo de los Marinos of the valley of Cauca, one of the tallest palm-trees, is the Cocus butyracea of Linnaeus.); the Cocos butyracea, called here palma dolce or palma real, and very different from the palma real of the island of Cuba; the palma amarga, with fan-leaves that serve to cover the roofs of houses, and the latta,* (* Perhaps of the species of Aiphanes.) resembling the small piritu palm-tree of the Orinoco. This variety of palm-trees was remarked by the first Conquistadores.* (* Pedro de Cieca de Leon, a native of Seville, who travelled in 1531, at the age of thirteen years, in the countries I have described, observes that Las tierras comarcanas del Rio Cenu y del Golfo de Uraba estan llena de unos palmares muy grandes y espessos, que son unos arboles gruessos, y llevan unas ramas como palma de datiles. [The lands adjacent to the Rio Cenu and the Gulf of Uraba are full of very tall, spreading palm-trees. They are of vast size and are branched like the date-palm.] See La Cronica del Peru nuevamenta escrita, Antwerp 1554 pages 21 and 204.) The Alfonsia, or rather the species of Elais, which we had nowhere else seen, is only six feet high, with a very large trunk; and the fecundity of its spathes is such that they contain more than 200,000 flowers. Although a great number of those flowers (one tree bearing 600,000 at the same time) never come to maturity,* the soil remains covered with a thick layer of fruits. (* I have carefully counted how many flowers are contained in a square inch on each amentum, from 100 to 120 of which are found united in one spathe.) We often made a similar observation under the shade of the mauritia palm-tree, the Cocos butyracea, the Seje and the Pihiguao of the Atabapo. No other family of arborescent plants is so prolific in the development of the organs of flowering. The almond of the Corozo del Sinu is peeled in the water. The thick layer of oil that swims in the water is purified by boiling, and yields the butter of Corozo (manteca de Corozo) which is thicker than the oil of the cocoa-tree, and serves to light churches and houses. The palm-trees of the section of Cocoinies of Mr. Brown are the olive-trees of the tropical regions. As we advanced in the forest, we began to find little pathways, looking as though they had been recently cleared out by the hatchet. Their windings displayed a great number of new plants: Mougeotia mollis, Nelsonia albicans, Melampodium paludosum, Jonidium anomalum, Teucrium palustre, Gomphia lucens, and a new kind of Composees, the Spiracantha cornifolia. A fine Pancratium embalmed the air in the humid spots, and almost made us forget that those gloomy and marshy forests are highly dangerous to health.
After an hour's walk we found, in a cleared spot, several inhabitants employed in collecting palm-tree wine. The dark tint of the zambos formed a strong contrast with the appearance of a little man with light hair and a pale complexion who seemed to take no share in the labour. I thought at first that he was a sailor who had escaped from some North American vessel; but I was soon undeceived. This fair-complexioned man was my countryman, born on the coast of the Baltic; he had served in the Danish navy and had lived for several years in the upper part of the Rio Sinu, near Santa Cruz de Lorica. He had come, to use the words of the loungers of the country para ver tierras, y pasear, no mas (to see other lands, and to roam about, nothing else.) The sight of a man who could speak to him of his country seemed to have no attraction for him; and, as he had almost forgotten German without being able to express himself clearly in Spanish, our conversation was not very animated. During the five years of my travels in Spanish America I found only two opportunities of speaking my native language. The first Prussian I met with was a sailor from Memel who served on board a ship from Halifax, and who refused to make himself known till after he had fired some musket-shot at our boat. The second, the man we met at the Rio Sinu, was very amicably disposed. Without answering my questions he continued repeating, with a smile, that the country was hot and humid; that the houses in the town of Pomerania were finer than those of Santa Cruz de Lorica; and that, if we remained in the forest, we should have the tertian fever (calentura) from which he had long suffered. We had some difficulty in testifying our gratitude to this good man for his kind advice; for according to his somewhat aristocratic principles, a white man, were he bare-footed, should never accept money "in the presence of those vile coloured people!" (gente parda). Less disdainful than our European countryman, we saluted politely the group of men of colour who were employed in drawing off into large calabashes, or fruits of the Crescentia cujete, the palm-tree wine from the trunks of felled trees. We asked them to explain to us this operation, which we had already seen practised in the missions of the Cataracts. The vine of the country is the palma dolce, the Cocos butyracea, which, near Malgar, in the valley of the Magdalena, is called the wine palm-tree, and here, on account of its majestic height, the royal palm-tree. After having thrown down the trunk, which diminishes but little towards the top, they make just below the point whence the leaves (fronds) and spathes issue, an excavation in the ligneous part, eighteen inches long, eight broad, and six in depth. They work in the hollow of the tree, as though they were making a canoe; and three days afterwards this cavity is found filled with a yellowish-white juice, very limpid, with a sweet and vinous flavour. The fermentation appears to commence as soon as the trunk falls, but the vessels preserve their vitality; for we saw that the sap flowed even when the summit of the palm-tree (that part whence the leaves sprout out) is a foot higher than the lower end, near the roots. The sap continues to mount as in the arborescent Euphorbia recently cut. During eighteen to twenty days, the palm-tree wine is daily collected; the last is less sweet but more alcoholic and more highly esteemed. One tree yields as much as eighteen bottles of sap, each bottle containing forty-two cubic inches. The natives affirm that the flowing is more abundant when the petioles of the leaves, which remain fixed to the trunk, are burnt.
The great humidity and thickness of the forest forced us to retrace our steps and to gain the shore before sunset. In several places the compact limestone rock, probably of tertiary formation, is visible. A thick layer of clay and mould rendered observation difficult; but a shelf of carburetted and shining slate seemed to me to indicate the presence of more ancient formations. It has been affirmed that coal is to be found on the banks of the Sinu. We met with Zambos carrying on their shoulders the cylinders of palmetto, improperly called the cabbage palm, three feet long and five to six feet thick. The stem of the palm-tree has been for ages an esteemed article of food in those countries. I believe it to be wholesome although historians relate that, when Alonso Lopez de Ayala was governor of Uraba, several Spaniards died after having eaten immoderately of the palmetto, and at the same time drinking a great quantity of water. In comparing the herbaceous and nourishing fibres of the young undeveloped leaves of the palm-trees with the sago of the Mauritia, of which the Indians make bread similar to that of the root of the Jatropha manihot, we involuntarily recollect the striking analogy which modern chemistry has proved to exist between ligneous matter and the amylaceous fecula. We stopped on the shore to collect lichens, opegraphas and a great number of mosses (Boletus, Hydnum, Helvela, Thelephora) that were attached to the mangroves, and there, to my great surprise, vegetating, although moistened by the sea-water.