We Passed Fifty Leagues West Of Cape Bojador, Cape Blanco, And The Cape Verd Islands.

A few land birds, which had been driven to sea by the impetuosity of the wind followed us for several days.

The latitude diminished rapidly, from the parallel of Madeira to the tropic. When we reached the zone where the trade-winds are constant, we crossed the ocean from east to west, on a calm sea, which the Spanish sailors call the Ladies' Gulf, el Golfo de las Damas. In proportion as we advanced towards the west, we found the trade-winds fix to eastward.

These winds, the most generally adopted theory of which is explained in a celebrated treatise of Halley,* are a phenomenon much more complicated than most persons admit. (* The existence of an upper current of air, which blows constantly from the equator to the poles, and of a lower current, which blows from the poles to the equator, had already been admitted, as M. Arago has shown, by Hooke. The ideas of the celebrated English naturalist are developed in a Discourse on Earthquakes published in 1686. "I think (adds he) that several phenomena, which are presented by the atmosphere and the ocean, especially the winds, may be explained by the polar currents." - Hooke's Posthumous Works page 364.) In the Atlantic Ocean, the longitude, as well as the declination of the sun, influences the direction and limits of the trade-winds. In the direction of the New Continent, in both hemispheres, these limits extend beyond the tropics eight or nine degrees; while in the vicinity of Africa, the variable winds prevail far beyond the parallel of 28 or 27 degrees. It is to be regretted, on account of the progress of meteorology and navigation, that the changes of the currents of the equinoctial atmosphere in the Pacific are much less known than the variation of these same currents in a sea that is narrower, and influenced by the proximity of the coasts of Guinea and Brazil. The difference with which the strata of air flow back from the two poles towards the equator cannot be the same in every degree of longitude, that is to say, on points of the globe where the continents are of very different breadths, and where they stretch away more or less towards the poles.

It is known, that in the passage from Santa Cruz to Cumana, as in that from Acapulco to the Philippine Islands, seamen are scarcely ever under the necessity of working their sails. We pass those latitudes as if we were descending a river, and we might deem it no hazardous undertaking if we made the voyage in an open boat. Farther west, on the coast of Santa Martha and in the Gulf of Mexico, the trade-wind blows impetuously, and renders the sea very stormy.* (* The Spanish sailors call the rough trade-winds at Carthagena in the West Indies los brisotes de Santa Martha; and in the Gulf of Mexico, las brizas pardas. These latter winds are accompanied with a grey and cloudy sky.)

The wind fell gradually the farther we receded from the African coast: it was sometimes smooth water for several hours, and these short calms were regularly interrupted by electrical phenomena. Black thick clouds, marked by strong outlines, rose on the east, and it seemed as if a squall would have forced us to hand our topsails; but the breeze freshened anew, there fell a few large drops of rain, and the storm dispersed without our hearing any thunder. Meanwhile it was curious to observe the effect of several black, isolated, and very low clouds, which passed the zenith. We felt the force of the wind augment or diminish progressively, according as small bodies of vesicular vapour approached or receded, while the electrometers, furnished with a long metallic rod and lighted match, showed no change of electric tension in the lower strata of the air. It is by help of these squalls, which alternate with dead calms, that the passage from the Canary Islands to the Antilles, or southern coast of America, is made in the months of June and July.

Some Spanish navigators have lately proposed going to the West Indies and the coasts of Terra Firma by a course different from that which was taken by Columbus. They advise, instead of steering directly to the south in search of the trade-winds, to change both latitude and longitude, in a diagonal line from Cape St. Vincent to America. This method, which shortens the way, cutting the tropic nearly twenty degrees west of the point where it is commonly cut by pilots, was several times successfully adopted by Admiral Gravina. That able commander, who fell at the battle of Trafalgar, arrived in 1802 at St. Domingo, by the oblique passage, several days before the French fleet, though orders of the court of Madrid would have forced him to enter Ferrol with his squadron, and stop there some time.

This new system of navigation shortens the passage from Cadiz to Cumana one-twentieth; but as the tropic is attained only at the longitude of forty degrees, the chance of meeting with contrary winds, which blow sometimes from the south, and at other times from the south-west, is more unfavourable. In the old system, the disadvantage of making a longer passage is compensated by the certainty of catching the trade-winds in a shorter space of time, and keeping them the greater part of the passage. At the time of my abode in the Spanish colonies, I witnessed the arrival of several merchant-ships, which from the fear of privateers had chosen the oblique course, and had had a very short passage.

Nothing can equal the beauty and mildness of the climate of the equinoctial region on the ocean. While the trade wind blew strongly, the thermometer kept at 23 or 24 degrees in the day, and at 22 or 22.5 degrees during the night. The charm of the lovely climates bordering on the equator, can be fully enjoyed only by those who have undertaken the voyage from Acapulco or the coasts of Chile to Europe in a very rough season.

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