The steamers leave Manaos, on the Amazon, for San Antonio on the 27th of every month, and in the busy seasons of the year there is generally an extra steamer about the middle of the month. Between Manaos and Para there is always a fortnightly and generally a weekly service each way, and from Manaos most of the tributaries of the Amazon have a monthly service as far as they are navigable. Steam navigation on the Amazon had its beginning in 1852, but its growth has not been rapid, owing to the slow development of commerce. In 1867 Brazil declared the Amazon open to the ships of all nations, but practically the navigation of the river is under the Brazilian flag. Steamers of any nationality may ascend to Manaos, one thousand miles above Para; from that point Brazilian steamers run to the frontier of Peru, where they connect with Peruvian steamers navigating almost to the base of the great Andean chain. At present the entire service is performed by about fifty steamers, some of large size and others light enough for the fancy of the western captain who desired a craft that could run where a heavy dew had fallen. The smallest of the steamers is less than twenty tons' burden, while the largest exceeds a thousand tons. The following note by Colonel Church will give an idea of the extent of the navigable waters of the Amazon: "South America contains seven millions of square miles. The Amazon River drains over one third of this vast area. Its basin is more than twice the size of the valley of the Mississippi. It would hold forty-nine countries the size of England. Only by floating on the majestic tide of the Amazon does one get an idea of its mass of waters. The Mississippi River, poured into it near its mouth, would not raise it six inches. In Bolivia, on the Beni branch of its Madeira affluent, two thousand miles from its outlet, it is one hundred and seventy feet deep! It presents still more astonishing soundings the same distance up the main stream. With its branches it offers not less than fifteen thousand miles of waters suitable for steamboat navigation. The Bolivian affluents of its main branch alone count three thousand miles of river navigation. One half of this is suitable for steamers drawing six feet of water, and the other half for craft drawing three feet." The great lack of the Amazon Valley is in population; until it is peopled it will be impossible to develop commerce to any great extent. There are not fifty thousand inhabitants on the banks of the great river from a point one hundred miles above Para to the base of the Andes; Professor Orton says the Amazon Valley is the most thinly peopled region on the surface of the globe, with the exception of the great deserts and the polar zones. Even including the savage Indians who dwell away from the rivers, the number of inhabitants is not great.