I was certain that I had, and directly afterwards put down, as well as I could remember, all Captain Frankland had said. The next day we sighted Saint Vincent, one of the ten islands which form the Cape de Verd group, so-called from being off the Cape de Verds, on the coast of Africa. The islands belong to the Portuguese. They produce all sorts of tropical fruits and vegetables, so that ships often touch here to be supplied with them. A large number of the inhabitants are black, or of a very dark hue. Instead of standing directly for the Brazils, Captain Frankland shaped a course almost across the Atlantic for the coast of South America. He did this, he explained to Gerard and me, to get the wind, which generally blows off that coast when the north-east trade failed us; and to avoid the equatorial calms, in which, away from the land, vessels are often baffled for days together. I found, after I had been some time at sea, "That the longest way round is often the shortest way there," as the saying is. In tropical latitudes, winds from different quarters blow with great regularity in different places at certain seasons of the year. The great object of a master is, to find where the wind is blowing which will be fair for him. The two most regular winds are the north-east and south-east trade-winds which blow from either side of the equator, and meet in a wide belt of calms found under it. There are currents in the air as well as in the ocean; and Silas told me that he has more than once passed ships at sea right before the wind--steering north, for instance, while his ship, with an equally fair breeze, has been standing to the south. Formerly, ships used to be steered as far south as they could get before the trade-winds; and then often found themselves baffled for days, if not weeks together, in the calm latitudes off the coast of Africa, when, if they had stood boldly across the ocean, as we were now doing, they would never have wanted a wind move or less fair. Thus it will be seen that in navigation there are currents in the sea and currents in the air to be considered, and that it requires a great deal of forethought, and knowledge, and experience, to take a ship in safety and with speed round the world. We were bowling along in grand style before the north-east trade-wind, when Gerard stopped his father in his morning walk on deck. "I say, father, can you tell Harry and me all about this trade-wind, which we have got hold of it seems?" said he with a grave look, as if he wished to become very learned.