“It now became an interesting question, which of these two streams is what the Minnetarees call Ahmateahza, or Missouri, which they describe as approaching very near to the Columbia.  On our right decision much of the fate of the expedition depends; since if, after ascending to the Rocky Mountains or beyond them, we should find that the river we were following did not come near the Columbia, and be obliged to return, we should not only lose the travelling season, two months of which have already elapsed, but probably dishearten the men so much as to induce them either to abandon the enterprise, or yield us a cold obedience, instead of the warm and zealous support which they have hitherto afforded us.  We determined, therefore, to examine well before we decided on our future course.  For this purpose we despatched two canoes with three men up each of the streams, with orders to ascertain the width, depth, and rapidity of the current, so as to judge of their comparative bodies of water.  At the same time parties were sent out by land to penetrate the country, and discover from the rising grounds, if possible, the distant bearings of the two rivers; and all were directed to return toward evening. . . .”

Both parties returned without bringing any information that would settle the point.  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.  Much rain had fallen, and their return was somewhat difficult, and not unattended with danger, as the following incident, which occurred on June 7th, will show: 

“In passing along the side of a bluff at a narrow pass thirty yards in length, Captain Lewis slipped, and, but for a fortunate recovery by means of his spontoon, would have been precipitated into the river over a precipice of about ninety feet.  He had just reached a spot where, by the assistance of his spontoon, he could stand with tolerable safety, when he heard a voice behind him cry out, ’Good God, captain, what shall I do?’ He turned instantly, and found it was Windsor, who had lost his foothold about the middle of the narrow pass, and had slipped down to the very verge of the precipice, where he lay on his belly, with his right arm and leg over