Personal Narrative of Travels to the Equinoctial Regions of America, During the Years 1799-1804, Vol.3 — 22 - Chapter 3.30, Part 1

CHAPTER 3.

30. PASSAGE FROM TRINIDAD DE CUBA TO RIO SINU.

CARTHAGENA.

AIR VOLCANOES OF TURBACO.

CANAL OF MAHATES.

On the morning of the 17th of March, we came within sight of the most eastern island of the group of the Lesser Caymans.

Comparing the reckoning with the chronometric longitude, I ascertained that the currents had borne us in seventeen hours twenty miles westward.

The island is called by the English pilots Cayman-brack, and by the Spanish pilots, Cayman chico oriental.

It forms a rocky wall, bare and steep towards the south and south-east.

The north and north-west part is low, sandy, and scantily covered with vegetation.

The rock is broken into narrow horizontal ledges.

From its whiteness and its proximity to the island of Cuba, I supposed it to be of Jura limestone.

We approached the eastern extremity of Cayman-brack within the distance of 400 toises.

The neighbouring coast is not entirely free from danger and breakers; yet the temperature of the sea had not sensibly diminished at its surface.

The chronometer of Louis Berthoud gave me 82 degrees 7 minutes 37 seconds for the longitude of the eastern cape of Cayman-brack.

The latitude reduced by the reckoning on the rhumbs of wind at the meridian observation, appeared to me to be 19 degrees 40 minutes 50 seconds.

As long as we were within sight of the rock of Cayman-brack sea-turtles of extraordinary dimensions swam round our vessel.

The abundance of these animals led Columbus to give the whole group of the Caymans the name of Penascales de las Tortugas (rocks of the turtles.

) Our sailors would have thrown themselves into the water to catch some of these animals; but the numerous sharks that accompany them rendered the attempt too perilous.

The sharks fixed their jaws on great iron hooks which were flung to them; these hooks were very sharp and (for want of anzuelos encandenados* (* Fish-hooks with chains.

)) they were tied to cords: the sharks were in this manner drawn up half the length of their bodies; and we were surprised to see that those which had their mouths wounded and bleeding continued to seize the bait over and over again during several hours.

* (* Vidimus quoque squales, quotiescunque, hamo icti, dimidia parte corporis e fluctibus extrahebantur, cito alvo stercus emittere haud absimile excrementis caninis.

Commovebat intestina (ut arbitramur) subitus pavor.

Although the form and number of teeth change with age, and the teeth appear successively in the shark genus, I doubt whether Don Antonio Ulloa be correct in stating that the young sharks have two, and the old ones four rows of grinders.

These, like many other sea-fish, are easily accustomed to live in fresh water, or in water slightly briny.

It is observed that sharks (tiburones) abound of late in the Laguna of Maracaybo, whither they have been attracted by the dead bodies thrown into the water after the frequent battles between the Spanish royalists and the Columbian republicans.

) At the sight of these voracious fish the sailors in a Spanish vessel always recollect the local fable of the coast of Venezuela, which describes the benediction of a bishop as having softened the habits of the sharks, which are everywhere else the dread of mariners.

Do these wild sharks of the port of La Guayra specifically differ from those which are so formidable in the port of the Havannah?

And do the former belong to the group of Emissoles with small sharp teeth, which Cuvier distinguishes from the Melandres, by the name of Musteli?

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.

)