The great valley of the Magdalena, extending from the Caribbean coast to the equatorial line, is one of inexhaustible resources. Its width varies from one hundred to one hundred and fifty miles before gradually sloping to a point in the northern borders of the equator. At the mouth of the river Cauca this valley branches off into another of less general width but of greater elevation, and consequently possesses a more equable and temperate climate. The river Cauca is itself navigable by a light-draught steamer as far as Cali, a point less than eighty miles from the port of Buenaventura on the Pacific coast. The lower valley of the Magdalena is one vast alluvial plain, a large portion of which is subject to periodical overflow. In fact, during the rainy season the greater portion of it is usually under water. This, however, might be prevented, and the fertile lands reclaimed, by a system of dikes far less expensive than those of the lower Mississippi. But in a country where population is sparse, and Nature lavish in her bounties, such enterprises are not usually undertaken. The distance from Barranquilla to Honda, the head of navigation on the Magdalena, is seven hundred and eighty miles, following the course of the river, but in a direct line is only about one-third of that distance. The journey by boat requires from ten to thirty days, according to the condition of the river. In the rainy season the banks are full, and the current so strong that the little steamers cannot make much progress; but if the moon is bright enough to show the course, they are kept in motion night and day. In the dry season the river is shallow, and the boats have to tie up at dark, and remain so till daylight. Then, on nearly every voyage they run aground, and often stick for a day or two, sometimes a week, before they can be got off. The boats are similar to those used upon the Ohio and other rivers, with a paddle-wheel behind, and draw only a foot or two of water even when heavily laden, so that they can go over the bars. There are two steamboat companies, both with United States capital; one is managed by a Mr. Joy, and the other by a Mr. Cisneros, a naturalized Italian. During the revolution all the boats were seized by the insurgents. Their sides were covered with corrugated iron, so as to make them bullet-proof, a small cannon or two mounted upon the decks, and the cabins filled with sharp-shooters. So prepared, they were used as gun-boats, and were quite effective. Many of them were destroyed, so that transportation facilities upon the Magdalena are not so good as they were. [Illustration: ON THE MAGDALENA.] The first two hundred miles is a continuous swamp; the next three hundred miles is a vast plain, which is under water about two months in the year, during the floods that follow the rainy season, but at other times is covered with cattle, which are driven into the mountains before the floods come.