Red river takes its name from the colour of its water, which is in time of floods of a bright red, and partakes more or less of this colour throughout the year. There can be no doubt the colouring matter on which this tinge depends is derived from the red sandstone of the salt formation already described when speaking of the sources of the Canadian river of Arkansa, although no person qualified to give a satisfactory account of the country has hitherto traced Red river to that formation. We propose to add some brief notices of this important river, derived from the unpublished materials of the exploring party sent out by the government of the United States in 1806; also from the notes of Major Long, who visited the upper settlements in 1817; not neglecting such additional information from the works of Darby, Nuttall, and others who have written of Louisiana, as may appear deserving of confidence. Red river was explored at a very early period by the French, but their examinations appear to have extended no farther than to the country of the Natchitoches and the Cadoes;[55] and although subsequent {167} examinations have a little enlarged our acquaintance with its upper branches, we are still unfortunately ignorant of the position of its sources. Three years after the cession of Louisiana to the United States, a small party, known by the name of the "Exploring Expedition of Red river," and consisting of Captain Sparks, Mr. Freeman, Lieut. Humphrey, and Dr. Custis, with seventeen private soldiers, two non-commissioned officers, and a black servant, embarked from St. Catherine's landing, near Natchez, on board several barges and small boats, with instructions to ascend Red river to its sources.[56] On the 3d of May 1806 they entered Red river, expecting to be able to ascend with their boats to the country of the Pawnee Piqua Indians. Here it was their intention to leave their boats, and packing their provision on horses which they should purchase of the Pawnees, they were to "proceed to the top of the mountains," the distance being, as they believed, about three hundred miles.