On the 30th of April, 1803, the treaty with France ceding Louisiana was consummated, and on June 20th Lewis's instructions were signed and he departed for La Charette by way of Pittsburg and the Ohio.[66] Congress ratified the purchase on October 17th the same year. Travelling was mainly by water in those days, and that seems to be the reason why Lewis stuck to boat travelling when horses would have been so much easier across the western prairies. They were permitted to return by sea, if necessary and possible, and Lewis carried letters of credit which would have obtained money for him in any port, or on any ship, the world round. The object of the exploration as announced was to find a waterway across the continent, but Jefferson doubtless had more in view than such a diplomatic statement would imply. Intercourse with natives, he particularly directed, should be friendly and conciliatory. With forty-two men and three boats Lewis and Clark left their winter quarters on May 14, 1804, and proceeded up the Missouri, passing the village of St. Charles, with a French Canadian population of 450, and a little above it a small group of American farmers. On the 25th they passed La Charette, the last settlement, and were then fairly under way. Two rafts were met June 12th, on one of which was a trapper named Dorion who had been for more than twenty years among the Sioux. They engaged him to go with the party and this increased the number to forty-five all told. There were nine young men from Kentucky, fourteen American soldiers who had volunteered, a French interpreter, a French hunter, and a negro belonging to Clark. All but the negro were enlisted as privates and drew pay from the Government. Besides these there were a corporal and six soldiers, who were to turn back at the Mandan towns, and nine _voyageurs_. One boat was fifty-five feet long, drawing three feet of water, with a square sail and twenty-two oars, and was armed with a swivel at the bow. There was a deck of ten feet at the bow and stern, while the middle was covered with lockers which could be raised to form a breastwork. The other boats were open, one having six and the other seven oars. Two horses were taken along the bank. Had they abandoned the boat idea and taken to horses they might have gone to the mouth of the Columbia while they were going to the Mandan towns, but they did not know how great a bend the Missouri makes. They pushed steadily up the river, meeting many natives and having friendly relations with them, and the last of October arrived at the Mandan towns, having consumed five and a half months in making the ascent.