Which was the true Missouri still remained uncertain.

Under these circumstances, it became necessary that there should be a more thorough exploration, and the next morning Captains Lewis and Clark set out at the head of two separate parties, the former to examine the north, and the latter the south fork.

In his progress Captain Lewis and his party were frequently obliged to quit the course of the river and cross the plains and hills, but he did not lose sight of its general direction, and carefully took the bearings of the distant mountains.

On the morning of the third day he became convinced that this river pursued a course too far north for his contemplated route to the Pacific, and he accordingly determined to return, but judged it advisable to wait till noon, that he might obtain a meridian altitude.

In this, however, he was disappointed, owing to the state of the weather.