In 1803, Mr. Jefferson, being then President of the United States, proposed to Congress to send an exploring party to trace the Missouri to its source; to cross the highlands, and follow the best water communication which might offer itself, to the Pacific Ocean. Congress approved the proposal, and voted a sum of money to carry it into execution. Capt. Lewis, who had then been two years with Mr. Jefferson as his private secretary, immediately renewed his solicitations to have the direction of the expedition. Mr. Jefferson had now had opportunity of knowing him intimately, and believed him to be brave, persevering, familiar with the Indian character and customs, habituated to the hunting life, honest, and of sound judgment. He trusted that he would be careful of those committed to his charge, yet steady in the maintenance of discipline. On receiving his appointment, Capt. Lewis repaired to Philadelphia, and placed himself under its distinguished professors, with a view to acquire familiarity with the nomenclature of the natural sciences. He selected, as his companion in the proposed expedition, William Clarke, a brother-officer, known and esteemed by him. While these things were going on, the treaty with France was concluded, by which the country of Louisiana was ceded to the United States. This event, which took place in 1803, greatly increased the interest felt by the people of the United States in the proposed expedition. In the spring of 1804, the preparations being completed, the explorers commenced their route. The party consisted of nine young men from Kentucky, fourteen soldiers of the United-States army who volunteered their services, two French watermen, an interpreter, a hunter, and a black servant of Capt. Clarke. In addition to these, a further force of fifteen men attended on the commencement of the expedition to secure safety during the transit through some Indian tribes whose hostility was apprehended. The necessary stores were divided into seven bales and one box, the latter containing a small portion of each article in case of a loss of any one of the bales. The stores consisted of clothing, working tools, ammunition, and other articles of prime necessity. To these were added fourteen bales and one box of Indian presents, composed of richly laced coats and other articles of dress, medals, flags, knives, and tomahawks for the chiefs; ornaments of different kinds, particularly beads, looking-glasses, handkerchiefs, paints, and generally such articles as were deemed best calculated for the taste of the Indians. The company embarked on board of three boats. The first was a keel-boat, fifty-five feet long, carrying one large square sail and twenty-two oars. A deck of ten feet, at each end, formed a forecastle and cabin. This was accompanied by two open boats of six oars. Two horses were to be led along the banks of the river, for bringing home game, or hunting in case of scarcity.