The former passage to the south coast had been made on the port tack, by standing out into the southeast trades, and forty-one days had expired on reaching Benguela. This passage was made on the starboard tack, in-shore, and occupied but twenty-two days to Ambriz--a run of four days from Benguela. The great advantages of the in-shore passage will be made manifest in a letter hereafter to be referred to. Greater alternations of weather, pleasant and squally, with now and then a strong tornado, occur in-shore; but a good look-out will enable a man-of-war to encounter all these with safety. Besides a number of legal traders, on the passage down, several British cruisers were boarded, who reported the slave-trade as being exceedingly dull. Three days were spent in Loanda, and then cruising for the same length of time, with the new commander of the British southern division, was resumed off Ambriz. Thence the vessel proceeded down the coast towards the Congo River, where the new commander of the steamer Fire-Fly boarded the Perry, when at a distance of four miles from his own vessel. Passed the Congo, after encountering a tornado. This river is more than two leagues broad at its mouth. At the distance of eight or ten miles seaward, in a northwesterly direction, the water preserves its freshness; and at the distance of fifty and even sixty miles, it has a black tinge. Here are often seen small islands floating seaward, formed of fibrous roots, bamboo, rushes and long grass, and covered with birds. The banks of the Congo are lined with low mangrove bushes, with clumps of a taller species interspersed, growing to the height of sixty and seventy feet. Palm-trees, and others of a smaller growth, are seen with a rich and beautiful foliage. In going up the river, the southern shore, where there is plenty of water close in with the land, should be kept aboard. The current is so strong--often running six miles an hour off Shark’s Point--that an exceedingly fresh sea-breeze is necessary in order to stem the stream. The greatest strength of this current, however, is superficial, not extending more than six or eight feet in depth. The Congo, like all rivers in Africa, except the Nile, is navigable but a short distance before reaching the rapids. The great central regions being probably not less than three thousand feet in altitude above the sea, these rapids are formed by a sudden depression of the surface of the country towards the sea, or by a bed of hard rocks stretching across the basin of the river.