a northern point, and as we coasted along its side, within two miles passed a smaller island, and half a mile above reached the head of another.  All these islands are small, and most of them contain some timber.  Three quarters of a mile beyond the last, and at the distance of eighteen miles from our encampment, we came to for the night in a handsome low cottonwood plain on the south, where we remained for the purpose of making some celestial observations during the night, and of examining in the morning a large river which comes in opposite to us.  Accordingly at an early hour,

Monday, 3d, we crossed and fixed our camp in the point, formed by the junction of the river with the Missouri.  It now became an interesting question which of these two streams is what the Minnetarees call Ahmateahza or the Missouri, which they described 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 had 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 had hitherto afforded us.  We determined, therefore, to examine well before we decided on our future course; and for this purpose 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 towards evening.  While they were gone we ascended together the high grounds in the fork of these two rivers, whence we had a very extensive prospect of the surrounding country:  on every side it was spread into one vast plain covered with verdure, in which innumerable herds of buffaloe were roaming, attended by their enemies the wolves:  some flocks of elk also were seen, and the solitary antelopes were scattered with their young over the face of the plain.  To the south was a range of lofty mountains, which we supposed to be a continuation of the South mountain, stretching themselves from southeast to northwest, and terminating abruptly about southwest from us.  These were partially covered with snow; but at a great distance behind them was a more lofty ridge completely covered with snow, which seemed to follow the same direction as the first, reaching from west to the north of northwest, where their snowy tops were blended with the horizon.  The direction of the rivers could not however be long distinguished, as they were soon lost in the extent of the plain.  On our return we continued our